Checking a set of hypotheses

The hypothesis concerns mutation accumulation during aging of the intestinal epithelium.

Matches this study. The study directly examines age-associated somatic mutations and structural rearrangements in intestinal stem cells of Drosophila. It matches the broad tissue-and-aging requirement, while its in vivo fly system differs from the proposed organoid experiment.

Frequent Somatic Mutation in Adult Intestinal Stem Cells Drives Neoplasia and Genetic Mosaicism during Aging (Results; Figures 1, 2, 5 and 6.)

A small group of rare, long-lived stem cell clones with inaccurate repair may contribute disproportionately to the mutational outcome of aging tissue.

Not verified in the article. The study identifies rearrangements in expanded neoplastic clones and infers possible repair or replication mechanisms from breakpoint sequences. It does not establish a rare, persistently inaccurate-repair clone population that disproportionately generates aging-associated mutations.

Frequent Somatic Mutation in Adult Intestinal Stem Cells Drives Neoplasia and Genetic Mosaicism during Aging (Results, Molecular Mechanisms of Somatic X-Linked Notch Deletions; Discussion.)

A single average measure of break closure speed is predicted to forecast future rearrangements less accurately than the proportion of clones with inaccurate repair.

Not verified in the article. None of the supplied studies compares average break closure speed with the proportion of inaccurate clones as predictors of future rearrangements.

The experiment must use organoids from different donors.

Matches this study. Organoid barcode analyses used crypts from six young and five aged individual mice, satisfying the use of organoids from different donors at this component level.

Reduced adhesion of aged intestinal stem cells contributes to an accelerated clonal drift (Results, Organoids from aged crypts show a clonal complexity similar to young organoids; Figure 3B.)

The initial clones in the organoids must be labeled.

Matches this study. Freshly isolated crypts were transduced with a lentiviral barcode library before organoid expansion, providing initial clonal labels. These labels were used to measure clonal abundance rather than repair accuracy.

Reduced adhesion of aged intestinal stem cells contributes to an accelerated clonal drift (Figure 3A; Materials and Methods, Crypt transduction with the barcode virus library and DNA harvest and amplification.)

The organoids must receive the same short pulse of breaks.

Different experimental conditions. The organoid experiments used ultraviolet exposure or two-hour cisplatin and illudin S treatments, with photoproduct removal and survival assays. These interventions differ from the specified uniform short pulse of breaks in labeled clones.

Different responses to DNA damage determine ageing differences between organs (Figure 6; Methods 4.7, Genotoxic sensitivity assay; Methods 4.8, Assessment of DNA lesion resolution in SCs.)

Early junction accuracy must be measured after the pulse of breaks.

Different experimental conditions. Breakpoint junctions were characterized retrospectively in spontaneous neoplasias. This differs from measuring early repair-junction accuracy immediately after a controlled pulse of breaks.

Frequent Somatic Mutation in Adult Intestinal Stem Cells Drives Neoplasia and Genetic Mosaicism during Aging (Results; Figures 5E and 6D, 6F; Molecular Mechanisms of Somatic X-Linked Notch Deletions.)

Descendants of the labeled clones must be sequenced after the same number of divisions.

Different experimental conditions. Integrated barcode sequences were sequenced after seven days of organoid culture. The study used elapsed culture time and barcode abundance, rather than descendant genome sequencing after equal numbers of divisions.

Reduced adhesion of aged intestinal stem cells contributes to an accelerated clonal drift (Figure 3A; Materials and Methods, Crypt transduction with the barcode virus library and DNA harvest and amplification.)

The primary outcome must be the probability of a new structural rearrangement per clone and division.

Different experimental conditions. Outcomes included frequencies of affected midguts and neoplasias, together with rearrangement structures. The probability of a new structural rearrangement per clone and division was not estimated.

Frequent Somatic Mutation in Adult Intestinal Stem Cells Drives Neoplasia and Genetic Mosaicism during Aging (Results; Figures 1C, 1G, 2E, 3 and 6.)

Two models must be compared on independent donors by their prediction errors for the primary outcome, using average break closure speed in one model and the proportion of clones with inaccurate junctions in the other.

Not verified in the article. The supplied studies contain no independent-donor comparison of prediction errors between the two specified models for rearrangements per clone and division.

The analysis must account for clones that are lost during the experiment.

Different experimental conditions. Repeated in vivo imaging explicitly counted lost and retained labeled clones over twelve weeks under calorie restriction and control diets. This establishes clone-loss measurement, but not attrition adjustment in the proposed organoid rearrangement-prediction analysis.

Calorie Restriction Increases the Number of Competing Stem Cells and Decreases Mutation Retention in the Intestine (Results, CR Results in Lower Mutation Retention Due to Stronger Stem Cell Competition; Figure 3A-D.)

The hypothesis is unsupported if average break closure speed predicts rearrangements at least as well as the accuracy distribution in an independent sample.

Not verified in the article. No supplied study evaluates whether average break closure speed predicts rearrangements at least as accurately as the repair-accuracy distribution in an independent sample.

The hypothesis is also unsupported if clonal selection fully explains the difference in predictive performance.

Not verified in the article. Although clonal competition and mutation retention were studied, no supplied experiment tests whether selection fully accounts for the difference in predictive performance between the specified repair measures.

During aging, the residual breaks that undergo slow repair may be determined by local DNA packing.

Not verified in the article. The supplied studies do not test whether local DNA packing determines the slowly repaired residual breaks associated with aging.

Dense local chromatin packing limits repair, and transient local relaxation should relieve this restriction; opening heterochromatin is proposed to be beneficial only near a break within it.

Not verified in the article. The experiments support chromatin-dependent restrictions on repair and a role for transient relaxation followed by heterochromatin restoration. They do not establish that opening is beneficial only near an internal break; persistent relaxation can instead promote erroneous end joining.

ATM Release at Resected Double-Strand Breaks Provides Heterochromatin Reconstitution to Facilitate Homologous Recombination (Results, Figures 3-6; Discussion, KAP-1-dependent heterochromatin facilitates HR)

The experiment should use fibroblasts with comparable break sites placed in dense and open chromatin.

Different experimental conditions. Comparable I-SceI sites and repair reporters were inserted into gene-rich and gene-poor regions, but the repair experiments used H1299 carcinoma cells rather than fibroblasts.

Pre-existing H4K16ac levels in euchromatin drive DNA repair by homologous recombination in S-phase (Results, Figures 1-2; Methods, Cell lines and DSB repair by NHEJ and HR assay)

Initial cutting should be equal before recruitment of the remodeling factor.

Not verified in the article. Equivalent cleavage between chromatin contexts and unchanged cleavage after targeted acetylation were demonstrated. Recruitment specifically after an equal initial cutting step was not established.

Pre-existing H4K16ac levels in euchromatin drive DNA repair by homologous recombination in S-phase (Results, Figure 2 and H4K16ac levels impact DSB repair by HR in gene-rich regions; Supplementary Figure 9)

A remodeling factor should be recruited transiently and locally near the break to produce brief relaxation of dense chromatin.

Different experimental conditions. Guide-directed dCas9-hMOF increased local histone acetylation next to repair reporters. This substitutes targeted acetylation for a demonstrated brief, post-cutting remodeling pulse that relaxes dense chromatin.

Pre-existing H4K16ac levels in euchromatin drive DNA repair by homologous recombination in S-phase (Results, Figure 4; Supplementary Figures 7-9)

The local relaxation should occur without global loosening of chromatin packing.

Not verified in the article. Preservation of global chromatin packing during the proposed local relaxation intervention is not demonstrated in the supplied studies.

The experiment should include an inactive variant of the remodeling factor as a control.

Not verified in the article. The targeted acetylation experiment included dCas9-p300(Core), a different acetyltransferase construct. It does not verify the required inactive variant of the same remodeling factor.

Pre-existing H4K16ac levels in euchromatin drive DNA repair by homologous recombination in S-phase (Results, Figure 4c; Supplementary Figure 8)

The experiment should include the same remodeling factor without targeting as a control.

Not verified in the article. The supplied text does not verify a repair comparison using the same remodeling factor with and without targeting as the specified control.

The primary outcomes should be the proportion of precisely restored alleles in the dense region and the number of large rearrangements.

Different experimental conditions. Large deletions, inversions and translocations were assessed alongside mutagenic repair signatures in K562 cells. The assay explicitly cannot distinguish perfectly repaired DNA from uncut DNA, so it does not provide the required proportion of precisely restored alleles.

Impact of chromatin context on Cas9-induced DNA double-strand break repair pathway balance (Results, Detection of large genomic rearrangements and Supplementary Figure S2J-M; Limitations of study)

The repair outcomes should be assessed at equal cell survival.

Different experimental conditions. The drug screen measured viable cell counts and applied exclusion thresholds. Threshold-based filtering is not assessment of the proposed repair outcomes at equal cell survival.

Chromatin context-dependent effects of epigenetic drugs on CRISPR-Cas9 editing (Materials and methods, Viable cell count assay and Analysis of high-throughput sequencing data of the screens)

Transient local relaxation should improve repair accuracy in the dense chromatin region.

Different experimental conditions. Loss of dUtx reduced homologous recombination at facultative heterochromatic breaks in Drosophila. This tests the requirement for an endogenous demethylase, rather than improved repair accuracy after transient local recruitment in fibroblasts.

Double-strand breaks in facultative heterochromatin require specific movements and chromatin changes for efficient repair (Results, Figures 3-5; Supplementary Figure 7)

A change confined to the initial cutting frequency would refute the local-restriction hypothesis.

Not verified in the article. The study separates cleavage efficiency from recombination effects, which addresses the relevant confounder. It does not implement the proposed post-cutting fibroblast experiment or apply its cutting-only refutation criterion.

Pre-existing H4K16ac levels in euchromatin drive DNA repair by homologous recombination in S-phase (Results, Figure 2; Supplementary Figure 9)

The improvement in repair accuracy should be compared between dense and open chromatin; an equal improvement in the open region would refute the local-restriction hypothesis.

Different experimental conditions. Targeted acetylation was compared between gene-rich and gene-poor regions, and increased recombination only in euchromatic regions. This is a relevant contrasting component result, but it uses a different intervention, cell model and outcome from the proposed accuracy comparison.

Pre-existing H4K16ac levels in euchromatin drive DNA repair by homologous recombination in S-phase (Results, Figure 4b-c)

The experiment uses regenerating bronchial epithelium from young and elderly donors, with the donor serving as the independent experimental unit.

Different experimental conditions. The study compared donor-derived nasal cultures from children and elderly people and treated individuals as biological replicates. It used nasal differentiation cultures rather than the specified regenerating bronchial epithelium.

Age-Related Differences in Structure and Function of Nasal Epithelial Cultures From Healthy Children and Elderly People (Materials and Methods: Study Population; Culture of Primary Human Nasal Epithelial Cells; Preparation of Cell Lysates; Figure 2.)

During aging, individual newly formed cells may retain a normal ciliary beat frequency while particles become trapped at boundaries where neighboring groups have mismatched movement directions.

Not verified in the article. The authors observed opposing transport regions forming a vortex at their junction. Aging, newly formed cells with normal beat frequency, and particle trapping at such boundaries were not established together.

Induction of ciliary orientation by matrix patterning and characterization of mucociliary transport (Discussion: opposing transport directions and a circular hurricane at their junction.)

Multiciliated differentiation in airway epithelium is associated with the establishment of planar polarity, which coordinates ciliary orientation between neighboring cells.

Not verified in the article. The discussion describes planar polarity during differentiation using earlier literature. The study measured alignment after matrix patterning but did not directly establish the proposed differentiation-to-planar-polarity mechanism.

Induction of ciliary orientation by matrix patterning and characterization of mucociliary transport (Discussion: planar cell polarity, differentiation, and cited studies of ciliary orientation.)

Continuity of a directionally aligned ciliary path is proposed to determine the restoration of particle transport in aged airway epithelium.

Different experimental conditions. Patterned collagen promoted aligned cilia and continuous circular transport in human airway cultures. Restoration across a repaired zone in aged epithelium was not tested.

Induction of ciliary orientation by matrix patterning and characterization of mucociliary transport (Results: Collagen ridges induce ciliated cell alignment; Figures 1-2; Video S1.)

Coordinating ciliary orientation is predicted to improve particle transport even without an increase in cilia number.

Not verified in the article. Improved alignment and continuous transport were demonstrated, but unchanged cilia number was not established as a condition of that improvement.

Induction of ciliary orientation by matrix patterning and characterization of mucociliary transport (Results: Collagen ridges induce ciliated cell alignment; Figure 2.)

Directional mechanical conditioning is compared with alternating-direction flow of the same energy in regenerating epithelium from both young and elderly donors.

Different experimental conditions. The intervention was collagen substrate patterning compared with standard coating. Energy-matched directional and alternating-direction flow in both donor age groups was not tested.

Induction of ciliary orientation by matrix patterning and characterization of mucociliary transport (Materials and Methods: Preparation of collagen coated inserts; Discussion: attempts to use fluid flow.)

Basal body orientation, ciliary beat frequency, and particle transport speed are measured after the external flow has been switched off.

Not verified in the article. Basal body-basal foot orientation and transport speed were measured, but the required combination with beat-frequency measurements after withdrawal of conditioning flow was not reported.

Induction of ciliary orientation by matrix patterning and characterization of mucociliary transport (Materials and Methods: Analysis of ciliary orientation; Measurement of MCT rate; Figure 2.)

Humidity and mucus viscosity are controlled during the experiment.

Not verified in the article. Incoming air temperature and humidity were controlled in an ovine tracheal model, but mucus physical properties were explicitly not measured. Joint control of humidity and mucus viscosity in the proposed experiment is unverified.

Rapid changes in mucociliary transport in the tracheal epithelium caused by unconditioned room air or nebulized hypertonic saline and mannitol are not determined by frequency of beating cilia (Methods: Temperature and humidity settings; Discussion: limitations and mucus physical properties.)

The primary outcome is the proportion of particles that independently cross the entire repaired zone within a fixed time after external flow is withdrawn.

Different experimental conditions. Outcomes included cultures exhibiting continuous circular transport and average bead speed across sampled fields. They did not include the timed proportion of particles crossing an entire repaired zone after flow withdrawal.

Induction of ciliary orientation by matrix patterning and characterization of mucociliary transport (Results: Measurement of MCT; Figure 3; Videos S1-S3.)

Improved ciliary orientation is predicted to increase the primary outcome at a comparable ciliary beat frequency.

Not verified in the article. The alignment and transport results do not establish an increase in the specified crossing outcome at comparable ciliary beat frequency.

Induction of ciliary orientation by matrix patterning and characterization of mucociliary transport (Results: Collagen ridges induce ciliated cell alignment; Measurement of MCT.)

If particle transport fails to improve despite confirmed changes in orientation and a comparable ciliary beat frequency, the proposed geometric explanation for the loss of clearance is refuted.

Not verified in the article. No supplied study applied the proposed refutation test after confirming orientation changes and comparable beat frequency. Unsuccessful flow-alignment attempts do not meet those conditions.

Samples are randomly assigned to experimental conditions.

Not verified in the article. Random assignment of samples to the proposed experimental conditions is not documented in the supplied studies.

The outcome is assessed with blinding to experimental condition.

Not verified in the article. Blinded assessment of the proposed outcome is not documented; automated particle tracking alone does not establish blinding.

The conclusion remains indeterminate if the intervention does not reach its target or if the interval permits both explanations.

Not verified in the article. The supplied studies do not implement the specified indeterminate classification for failed target engagement or an interval permitting both explanations.

The experiment is intended to determine whether training ciliary beat direction during formation of the ciliated layer is worthwhile.

Different experimental conditions. Providing directional substrate cues during differentiation was tested successfully. The usefulness of flow-based training during regeneration in young and elderly donors remains untested.

Induction of ciliary orientation by matrix patterning and characterization of mucociliary transport (Results: Collagen ridges induce ciliated cell alignment; Discussion.)

The tested outcome is particle transport; a reduction in infection frequency lies outside the scope of the conclusion.

Matches this study. The experiments measured particle-marked mucus transport in culture. Reduced infection frequency was not an experimentally demonstrated outcome.

Induction of ciliary orientation by matrix patterning and characterization of mucociliary transport (Materials and Methods: Measurement of MCT rate; Results: Measurement of MCT; Figures 3-5.)

The proposed test concerns neuronal tissue from old animals and uses paired extracts from young and old mice.

Different experimental conditions. The neural-cell study used primary cortical astrocytes from postnatal day 3-4 mice and genetic knockouts, rather than paired neuronal extracts from young and old mice.

Synergistic decrease of DNA single-strand break repair rates in mouse neural cells lacking both Tdp1 and aprataxin (Materials and methods 4.2.2; Results; Figures 1-3)

Increasing FEN1 availability is predicted to reduce the deficit in completed repair predominantly for 5′-AMP-dRP in a context that permits strand displacement.

Not verified in the article. FEN1 processed both adenylated end types, and enzyme titration measured excision. Preferential rescue of completed repair of 5′-AMP-dRP in aged neuronal tissue was not tested.

Complementation of aprataxin deficiency by base excision repair enzymes (Results; Figures 1, 2 and 6)

The proposed bypass of aprataxin (APTX) deficiency relies on polymerase β and FEN1 processing an adenylated deoxyribose phosphate residue, as described in APTX-deficient cell extracts.

Matches this study. Polymerase β lyase and FEN1 excision activities removed the adenylated deoxyribose phosphate block in APTX-deficient human and chicken cell extracts.

Complementation of aprataxin deficiency by base excision repair enzymes (Results, processing of the 5′-adenylated-dRP-containing intermediate; Figures 2 and 4)

The bypass depends on end chemistry and a substrate structure permitting strand displacement and flap formation; equivalent bypass at every 5′-adenylated break is not assumed.

Not verified in the article. End chemistry affected polymerase β activity, and nucleotide-dependent FEN1 products were consistent with strand displacement. The proposed requirement for flap formation in completed bypass repair was not established.

Complementation of aprataxin deficiency by base excision repair enzymes (Results; Figures 1, 2 and 5; Supplementary Figure S3)

The alternative explanation is that APTX abundance alone remains the best predictor of repair for both end types.

Not verified in the article. No supplied study compared APTX abundance alone against end chemistry and FEN1 availability as predictors of completed repair of both substrates.

Compare reporters containing 5′-AMP-dRP with reporters containing 5′-AMP without the sugar residue, using the same sequence.

Different experimental conditions. The study compared nicked 5′-AMP and single-nucleotide-gapped 5′-AMP-dRP substrates. This changes substrate architecture; the specified same-sequence comparison isolating end chemistry is not verified.

Complementation of aprataxin deficiency by base excision repair enzymes (Materials and methods, preparation of DNA substrates; Scheme 1A-B; Figures 1-2)

Perform the comparisons with equal levels of APTX and polymerase.

Not verified in the article. Polymerase β levels were checked, including after FEN1 depletion, but comparisons included APTX-proficient and deficient cells. Equal APTX and polymerase levels across the proposed age comparison were not established.

Complementation of aprataxin deficiency by base excision repair enzymes (Cell lines and growth conditions; Results; Supplementary Figure S2)

Compare FEN1 removal, restoration of active FEN1, and addition of an inactive FEN1 variant.

Not verified in the article. FEN1 immunodepletion and preimmune-serum controls were performed, but the full comparison with active FEN1 add-back and an inactive FEN1 variant was absent.

Complementation of aprataxin deficiency by base excision repair enzymes (Materials and methods, immunodepletion of FEN1; Figure 4; Supplementary Figure S4)

The primary outcome is the fraction of precisely repaired full-length molecules after 60 minutes, with sequencing of the repair site.

Different experimental conditions. Measurements extended to 60 minutes but quantified blocking-group removal and excision products by electrophoresis, rather than sequence-verified, precisely repaired full-length molecules.

Complementation of aprataxin deficiency by base excision repair enzymes in mitochondrial extracts (Enzymatic assays in mitochondrial extracts; Figures 7-8)

Include an additional control that cannot form a flap to test the strand-displacement pathway.

Not verified in the article. No supplied study included the specified flap-incompetent control. A tetrahydrofuran substrate resistant to polymerase β lyase tests a different requirement.

Substrate-specific rescue of repair supports the proposed bypass mechanism.

Not verified in the article. Mitochondrial extracts showed substrate-dependent processing, including FEN1 activity on 5′-AMP-dRP but no detectable activity on nicked 5′-AMP. Substrate-specific rescue of completed repair by FEN1 restoration was not measured.

Complementation of aprataxin deficiency by base excision repair enzymes in mitochondrial extracts (Results; Figures 4 and 8)

Equal improvement in repair for both substrates does not support the proposed mechanism.

Not verified in the article. The proposed decision criterion based on equal improvement of completed repair for both reporters was not evaluated in the supplied studies.

Removal of the blocking group without correct ligation does not support the proposed mechanism.

Not verified in the article. The closest study measured removal of blocking groups and adjacent nucleotides. It did not couple those measurements to correct ligation to evaluate the proposed criterion.

Complementation of aprataxin deficiency by base excision repair enzymes (Enzymatic assays in cell extracts; Figures 1-4)

Ineffective FEN1 removal makes the depletion result uninformative.

Not verified in the article. Depletion was assessed through immunoblotting and activity assays, but an explicit criterion excluding ineffective depletion from interpretation was not reported.

Complementation of aprataxin deficiency by base excision repair enzymes (Immunodepletion of FEN1; Figure 4; Supplementary Figure S2D)

A repair result obtained in extracts does not establish restoration of nervous system function.

Not verified in the article. The authors treated effects on neurological disease as a hypothesis requiring further study. The proposed boundary between extract repair and restored nervous system function was not itself experimentally tested.

Complementation of aprataxin deficiency by base excision repair enzymes (Discussion, final paragraph)

The comparison hypothesis concerns APTX-dependent repair of abortive ligation during repeated stresses and the interval between injuries.

Not verified in the article. The comparison hypothesis about repeated stresses and injury intervals appears in the submitted proposal, but no supplied primary study tested that complete relationship.

In the proposed test, intervals are held equal while the possibility of enzymatic bypass varies with end chemistry and reporter structure.

Not verified in the article. No supplied study reproduced the proposed comparison that holds intervals equal while varying end chemistry and reporter structure in paired young and old neuronal extracts.

The experiment is a proposal, and its results have not yet been obtained.

Not verified in the article. The submission explicitly describes an unperformed experiment. This is the proposal's stated status, not an empirical result independently verified by a supplied primary study.

At equal total protrusion area on Descemet's membrane, a closed ring may allow fewer elderly endothelial cells to reach a defect than separate obstacles because protrusion connectivity creates a topological barrier to migration.

Different experimental conditions. Radially opened native corneal rims showed migration associated with disrupted physical barriers and contact inhibition. Closed and open protrusion configurations at equal area were not compared.

Early and late-onset cell migration from peripheral corneal endothelium (Materials and methods, Outer graft rim preparation; Discussion; Conclusion)

The competing explanation attributes the effect solely to the total area of surface unsuitable for cells.

Not verified in the article. The supplied studies do not test whether total unsuitable surface area alone explains an apparent effect of obstacle connectivity.

The stated supporting evidence includes a model of central endothelial removal from the human cornea in which ripasudil enhanced cell migration onto the stroma, while proliferation and changes in cell phenotype were also studied.

Matches this study. The human ex vivo model demonstrated ripasudil-enhanced migration from Descemet's membrane onto stroma and examined proliferation and phenotype. It modeled stripping by draping donor membrane onto stromal lenticules rather than reproducing a central circular wound.

Enhanced Migration of Fuchs Corneal Endothelial Cells by Rho Kinase Inhibition: A Novel Ex Vivo Descemet’s Stripping Only Model (Methods 2.6-2.10; Results 3.7-3.8; Figures 7-9)

The stated supporting evidence also includes an association between Descemet's membrane protrusion size and neighboring endothelial cell behavior in corneas with Fuchs dystrophy; individual protrusion area and connectivity of a series of protrusions can be separated.

Not verified in the article. The gutta-microenvironment study by Kocaba and colleagues is cited, but its methods and results are not supplied. Independent separation of individual gutta area and collective connectivity is therefore unverified.

Enhanced Migration of Fuchs Corneal Endothelial Cells by Rho Kinase Inhibition: A Novel Ex Vivo Descemet’s Stripping Only Model (Discussion; Reference 64)

The decisive experiment uses replicas of human Descemet's membrane seeded at the periphery with endothelial cells from elderly donors.

Different experimental conditions. Human donors aged 68-84 years were studied, but endothelial cells remained on native peripheral tissue embedded in hydrogel rather than being seeded peripherally onto membrane replicas.

Early and late-onset cell migration from peripheral corneal endothelium (Materials and methods, Corneas and Outer graft rim preparation; Table 1)

Construct ring-shaped and open obstacles on the replicas, matching the two configurations for obstacle height, chemistry and total area.

Different experimental conditions. Native tissue rings were cut radially to flatten them. This differs from constructing closed and open obstacles matched for height, chemistry and total area.

Early and late-onset cell migration from peripheral corneal endothelium (Materials and methods, Outer graft rim preparation; Figure 1)

Test the obstacle configurations both with and without ripasudil.

Different experimental conditions. Ripasudil-treated and untreated groups were compared on stromal substrates with or without a fibronectin-collagen coating. The required obstacle configurations were absent.

Enhanced Migration of Fuchs Corneal Endothelial Cells by Rho Kinase Inhibition: A Novel Ex Vivo Descemet’s Stripping Only Model (Table 2; Methods 2.6; Results 3.8; Figure 9)

Use a uniformly flat replica as a control.

Different experimental conditions. The migration control was an excised 4 mm central tissue graft, rather than a uniformly flat replica matched to the patterned substrates.

Early and late-onset cell migration from peripheral corneal endothelium (Materials and methods, Outer graft rim preparation; Figure 1)

Use cell tracking to verify passage across the ring.

Not verified in the article. No supplied experiment tracks cells to verify passage across an engineered protrusion ring.

Distinguish migration from cell division using cell tracking.

Different experimental conditions. Migration was measured with TrackMate, while proliferation was assessed separately using Ki-67 staining. Tracking-based separation of division and migration contributions to coverage was not demonstrated.

Enhanced Migration of Fuchs Corneal Endothelial Cells by Rho Kinase Inhibition: A Novel Ex Vivo Descemet’s Stripping Only Model (Methods 2.7 and 2.10; Results 3.7-3.8)

Confirm that the observed boundary-related difference cannot be explained solely by the diameter or height of an individual gutta.

Not verified in the article. No supplied experiment isolates a boundary-connectivity effect from the diameter or height of individual guttae.

The primary outcome is the fraction of the initially bare central disc covered by polarized living cells over seven days.

Different experimental conditions. Outcomes included 24-hour scratch closure, migration velocity and displacement, and monolayer staining at day 60. Seven-day central-disc coverage by polarized living cells was not measured.

Enhanced Migration of Fuchs Corneal Endothelial Cells by Rho Kinase Inhibition: A Novel Ex Vivo Descemet’s Stripping Only Model (Methods 2.4 and 2.7; Results 3.3 and 3.8; Figures 3 and 9)

An open migration path is predicted to produce greater central-disc coverage than a closed ring at equal total obstacle area.

Not verified in the article. Greater central coverage through an open path than through a closed ring at equal obstacle area is not demonstrated in the supplied studies.

Exact equality of coverage when migration is adequate would exclude a topological barrier within the selected range.

Not verified in the article. No supplied study applies the proposed equality criterion under verified adequate migration. A nonsignificant difference alone would not establish exact equality.

Repeat the experiment across independent donor lines and treat the endothelial cell donor as the independent experimental unit.

Different experimental conditions. Multiple donor tissues and cell lines were used, but repeated passages also counted as biological replicates. The proposed replica test with donor-level independence across donor lines was not performed.

Enhanced Migration of Fuchs Corneal Endothelial Cells by Rho Kinase Inhibition: A Novel Ex Vivo Descemet’s Stripping Only Model (Methods 2.1, 2.4, 2.7 and 2.11; Tables 1-2)

The replica models geometry and does not reproduce the full tissue composition in Fuchs dystrophy.

Different experimental conditions. The preparation retained native Descemet's membrane and attached trabecular meshwork. It was not a geometry-focused replica excluding the full diseased tissue composition.

Early and late-onset cell migration from peripheral corneal endothelium (Materials and methods, Outer graft rim preparation)

A positive result would justify checking for passages between protrusions when selecting a substrate.

Not verified in the article. The supplied studies do not establish a positive replica-test result supporting substrate selection according to passages between protrusions.

If the hypothesis is refuted, this approach does not proceed to the next stage.

Not verified in the article. A decision to stop further development after refutation of this topology-based approach is not specified in the supplied studies.

Randomize the allocation of experimental conditions.

Not verified in the article. Random allocation of experimental conditions is not documented in the supplied methods. Random cell migration describes cell movement, not allocation.

Conceal group codes during measurement.

Not verified in the article. Concealment of experimental group codes during measurement is not documented.

Before the main experiment, use an independent pilot to determine reproducibility, the working duration and the minimum distinguishable and biologically meaningful effect.

Not verified in the article. The supplied studies do not document an independent pilot jointly establishing reproducibility, working duration, and minimum distinguishable and biologically meaningful effects for this experiment.

Estimate the contrast and its confidence interval at the level of independent experimental units.

Not verified in the article. The methods mention 95% confidence intervals and biological replicates, but do not establish the required obstacle contrast and its confidence interval with endothelial donor as the independent unit.

Enhanced Migration of Fuchs Corneal Endothelial Cells by Rho Kinase Inhibition: A Novel Ex Vivo Descemet’s Stripping Only Model (Methods 2.11, Statistical Analysis)

The experiment is inconclusive between the explanations if the intervention fails to separate the groups or if the confidence interval permits substantial effects in both directions.

Not verified in the article. No supplied study specifies this inconclusive-result rule based on unsuccessful condition separation or an interval allowing substantial effects in both directions.

The hypothesis concerns restored bronchial epithelium in old age, specifically the functional relationship between secretory and ciliated cells.

Different experimental conditions. The study examines native human airways and differentiated airway cultures, with many tissue donors older than 60. It does not examine restored elderly bronchial epithelium as the specified experimental system.

Structure and function relationships of mucociliary clearance in human and rat airways (Results: Tracheo-bronchial ciliation is higher in human airways compared to rat; Discussion; Methods: Cell and tissue sourcing.)

At equal cell numbers and equal proportions of the two lineages, concentrating secretory cells in large patches far from ciliated cells may impair clearance of a viscous load because spatial separation limits coordinated transport.

Different experimental conditions. The study connects ciliary coverage, spacing and beat properties with particle transport and relates cell composition to directionality. It does not isolate secretory-cell patch size at equal cell numbers and lineage proportions under a viscous load.

Structure and function relationships of mucociliary clearance in human and rat airways (Results: Figures 3, 5 and 6; Methods: Physics-based model.)

The decisive experiment constructs mosaic epithelial sheets from cells of a single elderly donor, maintains equal proportions of secretory and ciliated cells, and compares different patch sizes to test whether reducing the distance between the two cell types improves transport.

Different experimental conditions. Cells from the same donor were differentiated in different media, producing different cell compositions. This substitutes medium-driven differentiation for constructing coarse and fine mosaics with fixed lineage proportions from an elderly donor.

Structure and function relationships of mucociliary clearance in human and rat airways (Results: In vitro airway cultures rarely match human mucociliary properties; Figure 4.)

The mosaic-sheet experiment must control epithelial polarity, total secretion, ciliary beat orientation, and permeability.

Not verified in the article. The mucin-deletion study measured transepithelial electrical resistance, ciliary beat frequency and ciliated area. It does not verify the complete combination of polarity, total secretion, beat orientation and permeability controls in a mosaic-sheet experiment.

MUC5B mobilizes and MUC5AC spatially aligns mucociliary transport on human airway epithelium (Results: Generation of MUC5B/AC-KO BCi-NS1.1 cultures; Figures 1B and 3H-J.)

The experiment must be repeated using cells from young donors.

Not verified in the article. The supplied studies do not report repeating the specified mosaic experiment in young donors.

The primary outcome is the fraction of a standardized mucus load that leaves the epithelial sheet within a specified interval after secretion stimulation; a finer mosaic is predicted to increase this fraction.

Different experimental conditions. The study measures tracer transport speed, distance per beat and directionality, including mucus-containing and ATP-treated cultures. These outcomes differ from the fraction of a standardized mucus load leaving a mosaic sheet after secretion stimulation.

Structure and function relationships of mucociliary clearance in human and rat airways (Methods: Live ciliary beat and particle clearance recordings; Particle clearance output metrics; Supplementary Figure 14 discussion.)

If the finer mosaic provides no advantage when total secretion and motility are equal, the proposed spatial cause is not established.

Not verified in the article. No supplied study tests whether a finer mosaic retains a clearance advantage when total secretion and motility are equal.

If the effect disappears after barrier integrity is equalized, the proposed spatial cause is not established.

Not verified in the article. No supplied study equalizes barrier integrity between mosaic conditions and then tests whether the spatial effect disappears. Measuring electrical resistance in mucin-deficient cultures does not perform this control.

The structure of an epithelial graft should be selected only after the finding is confirmed in a native airway explant.

Not verified in the article. Native human airway explants provide functional benchmarks, but the study does not confirm the proposed mosaic effect in an explant before selecting epithelial graft structure.

Structure and function relationships of mucociliary clearance in human and rat airways (Results: Figures 1-5; Discussion.)

The independent experimental unit is the bronchial epithelial donor.

Matches this study. Measurements across fields and samples were averaged to one value per donor and condition, matching donor-level replication. This methodological component is present in a different experiment.

Structure and function relationships of mucociliary clearance in human and rat airways (Methods: Statistical analysis; Figures 4 and 5.)

Samples must be randomly assigned to experimental conditions.

Not verified in the article. Random allocation of samples to the specified experimental conditions is not documented. Random selection of imaging regions in the mucin study is a different procedure.

The outcome must be assessed under blinded conditions.

Not verified in the article. Blinded assessment of the specified clearance outcome is not documented in the supplied studies.

The conclusion remains indeterminate if the intervention fails to reach its target or if the interval permits both explanations; the target, type of interval, and two explanations are not further specified.

Not verified in the article. The proposed indeterminate-conclusion rule is not reported. Its target, interval type and competing explanations remain unspecified, so more detailed matching would require assumptions.

The stated background finding is that prolonged Notch activation in airway basal-cell experiments directed differentiation predominantly toward the secretory lineage.

Matches this study. Sustained expression of the intracellular domains of NOTCH1 or NOTCH3 in primary human airway basal cells increased secretory differentiation and reduced ciliated differentiation. This directly supports the background component, with receptor specificity.

Activation of NOTCH1 or NOTCH3 Signaling Skews Human Airway Basal Cell Differentiation toward a Secretory Pathway (Results: Effects on Differentiation into Secretory and Ciliated Cells; Figures 6-8.)

The age window for the Notch intervention was not established in the cited background work.

Not verified in the article. The human Notch study does not establish an age window and discusses the originally cited Rock study secondarily. The original study's methods are not supplied, so its age-window limitation cannot be independently verified here.

Activation of NOTCH1 or NOTCH3 Signaling Skews Human Airway Basal Cell Differentiation toward a Secretory Pathway (Methods: Culture of Primary Human Airway Basal Cells; Discussion: Rock et al.; Reference 13.)

The target group is aging tissue or elderly people at risk of repeated injury.

Matches this study. The trial enrolled adults aged 65 years and older at risk of skin tears from care homes and the community, and recorded repeated injuries.

Pilot parallel randomised controlled trial of protective socks against usual care to reduce skin tears in high risk people: ‘STOPCUTS’ (Methods: Study setting, Inclusion criteria; Results: Table 1 and Primary clinical outcome.)

The proposed protection applies during patient transfers between a bed and a chair.

Different experimental conditions. Protection was prescribed throughout waking hours across daily activities. Chair-to-bed transfer injuries were recorded, but bed-chair transfers were not the defined intervention setting.

Pilot parallel randomised controlled trial of protective socks against usual care to reduce skin tears in high risk people: ‘STOPCUTS’ (Methods: Interventions; Results: Table 3 and causes of skin tears.)

A smooth protective sleeve that does not restrict movement is put on before the transfer.

Different experimental conditions. Participants received knee-length Kevlar-containing socks with an abrasion-resistant exterior and cushioning interior, worn daily for 16 weeks. These differ from a smooth forearm sleeve donned before transfer with verified freedom of movement.

Pilot parallel randomised controlled trial of protective socks against usual care to reduce skin tears in high risk people: ‘STOPCUTS’ (Background: protective sock construction; Methods: Interventions.)

Age-related skin fragility is hypothesized to reduce skin tolerance to shear during patient transfers.

Not verified in the article. Age-related skin deterioration and shear-related injury are discussed as background. The trial did not experimentally measure whether aging-related fragility reduces shear tolerance during transfers.

Pilot parallel randomised controlled trial of protective socks against usual care to reduce skin tears in high risk people: ‘STOPCUTS’ (Background: skin aging and skin-tear mechanisms; Discussion: Risk factors.)

The smooth sleeve is hypothesized to reduce forearm skin tears by reducing the force with which skin catches on fabric during transfers.

Not verified in the article. No supplied experiment measured skin-fabric catching force or linked its reduction by a smooth sleeve to fewer forearm tears during transfers.

Clusters of facilities using the usual transfer technique are compared with clusters using the same technique with the protective sleeve.

Different experimental conditions. Individuals were randomized to protective socks or usual care. Facility clusters and an identical standardized transfer technique in both groups were not tested; cluster randomization was only discussed for future research.

Pilot parallel randomised controlled trial of protective socks against usual care to reduce skin tears in high risk people: ‘STOPCUTS’ (Methods: Study design and Randomisation/allocation; Discussion: cluster randomisation.)

The injury assessor is blinded to the intervention group.

Matches this study. An independent specialist assessed wound severity from anonymized photographs while blinded. This matches blinded injury assessment for severity grading, although the nurses recording and initially assessing injuries were unblinded.

Pilot parallel randomised controlled trial of protective socks against usual care to reduce skin tears in high risk people: ‘STOPCUTS’ (Methods: Outcome measures; Skin tear severity rating scales; Results: Table 5.)

Transfer counts are recorded to quantify exposure.

Not verified in the article. Transfer counts were not reported. Diaries tracked sock wearing, and injury descriptions recorded causes without quantifying total transfer exposure.

The primary outcome is new forearm skin tears per thousand transfers, stratified by baseline skin fragility, and this rate is predicted to decrease with sleeve use.

Different experimental conditions. The trial reported lower-leg tears, affected participants, tear-free days and injuries per 100 person-days. It did not report forearm tears per thousand transfers or stratify that outcome by baseline skin fragility.

Pilot parallel randomised controlled trial of protective socks against usual care to reduce skin tears in high risk people: ‘STOPCUTS’ (Methods: Outcome measures; Results: Table 4 and Economic evaluation.)

The reduction in new skin tears is predicted to be particularly marked in people with low skin elasticity at the same level of assistance needed.

Not verified in the article. No supplied analysis tested whether protection is greater with low baseline skin elasticity while holding assistance needs constant.

Bench testing that confirms reduced catching, accompanied by an equivalent injury rate per transfer between the comparison groups, would refute the prediction.

Not verified in the article. No supplied study combined bench-confirmed reduction in catching with a clinical equivalence comparison of injuries per transfer.

The proposed experiment uses isolated old muscle fibers and their adjacent satellite-cell clones; the supporting biological observation concerns resting muscle in old mice.

Not verified in the article. The study examined resting aged mouse muscle and isolated old muscle fibers, but did not track identified adjacent clones in the proposed experimental system.

The aged niche disrupts muscle stem cell quiescence (Results; Figure 3a-d; Materials and Methods, Animals and Single muscle fibre and myogenic cell preparation.)

At the same mean concentration of fibroblast growth factor 2 (FGF2), several foci of high secretion from old muscle fibers are hypothesized to deplete adjacent stem-cell clones disproportionately to their size.

Not verified in the article. Restricted FGF2 expression regions and satellite-cell proximity were documented. Disproportionate clone depletion caused by focal secretion at matched mean concentration was not tested.

The aged niche disrupts muscle stem cell quiescence (Results, FGF2 is an aged niche-derived factor that induces satellite cells into cycle; Figure 3b-d.)

Local FGF2 excess from old muscle fibers is proposed to drive some adjacent satellite cells out of quiescence and reduce their ability to maintain the stem-cell pool.

Matches this study. Myofiber-derived FGF2 induced satellite-cell cycle entry, while manipulation of FGF signaling linked loss of quiescence to subsequent stem-cell depletion. This supports the local niche mechanism, without establishing an independent effect of spatial peaks.

The aged niche disrupts muscle stem cell quiescence (Results; Figures 3-5.)

The alternative explanation predicts equal loss of the stem-cell reserve at an equal total FGF2 dose.

Not verified in the article. The supplied studies do not compare equal total FGF2 doses with different spatial distributions to test equal reserve loss.

The decisive comparison places FGF2-bearing microparticles locally on isolated old muscle fibers or distributes the same particles uniformly.

Different experimental conditions. The particles delivered the inhibitor SU5402 intraperitoneally. They did not deliver FGF2 focally versus uniformly on isolated old muscle fibers.

The aged niche disrupts muscle stem cell quiescence (Materials and Methods, In-vivo pharmacological inhibition; Figure 3h-j.)

Empty microparticles serve as controls.

Different experimental conditions. Vehicle-treated beads controlled systemic inhibitor delivery. Empty microparticles controlling local FGF2 presentation on isolated fibers were not used.

The aged niche disrupts muscle stem cell quiescence (Materials and Methods, In-vivo pharmacological inhibition.)

FGF2 concentration and phosphorylated extracellular signal-regulated kinase (pERK) are mapped as functions of distance from the source.

Different experimental conditions. The study measured pERK responses to FGF2 and fibronectin by Western blot. It did not map FGF2 concentration and pERK jointly against distance from a source.

Targeting β1-Integrin Signaling Enhances Regeneration in Aged and Dystrophic Muscle in Mice (Results, β1-integrin crosstalks with FGF signaling in SCs; Figure 3c-d; Online Methods, SC isolation and myoblast culture.)

Barcoded cells are tracked to establish the outcomes of the original clones.

Different experimental conditions. Histone-associated fluorescent label retention and population transplantation distinguished proliferative histories and donor contributions. These labels did not identify individual original clones through unique barcodes.

The aged niche disrupts muscle stem cell quiescence (Figures 1-2; Materials and Methods, In-vivo cell division analysis and Satellite cell transplantation.)

After a common washout period, equal numbers of cells from the groups are transferred into identical FGF2-free conditions.

Different experimental conditions. Equal populations of 2,000 cells were transplanted into pre-injured adult hosts. This did not follow matched washout after spatial FGF2 exposure, and the recipient environment was not defined as FGF2-free.

The aged niche disrupts muscle stem cell quiescence (Figure 2a-e,o-r; Materials and Methods, Satellite cell transplantation.)

The primary outcome is the proportion of original clones that produce both a new muscle fiber and a reserve Pax7-positive cell during one regeneration cycle in the test culture.

Different experimental conditions. Donor-derived myonuclei and Pax7-positive cells were counted as population outcomes. The proportion of original clones generating both a new fiber and a reserve cell in one culture regeneration cycle was not measured.

The aged niche disrupts muscle stem cell quiescence (Figure 2d,e,l,m,q,r; Materials and Methods, Satellite cell transplantation and Analysis of satellite cells and their progeny.)

The focal group is predicted to have a lower proportion of clones retaining both fates than the uniformly distributed group, with the strongest effect immediately adjacent to the source.

Not verified in the article. No supplied study reports dual-fate clone frequencies for focal versus uniform exposure or their dependence on proximity to the source.

Equal primary outcomes in the presence of confirmed gradients would exclude a role for spatial FGF2 peaks.

Not verified in the article. No supplied experiment combines confirmed FGF2 gradients with equivalent clone-level primary outcomes to apply the proposed exclusion criterion.

The donor animal is the independent experimental unit.

Not verified in the article. The study reports animal replication and numbers of fibers sampled per animal. It does not specify donor-level analysis for the proposed paired spatial-exposure and clonal-outcome experiment.

The aged niche disrupts muscle stem cell quiescence (Materials and Methods, Purified muscle fibre extract and Analysis of satellite cells and their progeny; Figures 3-5.)

The response of an individual clone cannot be reconstructed from the total cell count.

Not verified in the article. Clonal-density cultures assessed growth and marker expression, but the study did not establish individual-clone dual outcomes or implement the proposed prohibition on inferring them from total cell counts.

The aged niche disrupts muscle stem cell quiescence (Materials and Methods, Analysis of satellite cells and their progeny; Figure 2k-n.)

Clones with missing baseline accounting preclude interpretation.

Not verified in the article. Wells lacking cells after four days were excluded from growth quantification. This is not baseline accounting of identified clones, and the stipulated interpretation rule was not reported.

The aged niche disrupts muscle stem cell quiescence (Materials and Methods, Analysis of satellite cells and their progeny.)

Experimental conditions are assigned randomly.

Matches this study. Experiments using animals or animal-derived cells were explicitly randomized based on litter. This methodological component was applied in a different biological comparison.

Targeting β1-Integrin Signaling Enhances Regeneration in Aged and Dystrophic Muscle in Mice (Online Methods, Statistical Analyses.)

Group codes are concealed during measurement.

Not verified in the article. Image processing and scoring are described as blinded, but the statistical section states that investigators were not blinded to outcome assessment. Concealment of group codes throughout measurement is therefore not verified.

Targeting β1-Integrin Signaling Enhances Regeneration in Aged and Dystrophic Muscle in Mice (Online Methods, Microscopy and image processing; Statistical Analyses.)

Before the main experiment, an independent pilot determines reproducibility, the working time frame, and the minimum distinguishable and biologically meaningful effect.

Not verified in the article. Sample size drew on previous variability and preliminary data. An independent pilot establishing reproducibility, the working time frame, and both detectable and biologically meaningful effects was not documented.

Targeting β1-Integrin Signaling Enhances Regeneration in Aged and Dystrophic Muscle in Mice (Online Methods, Statistical Analyses.)

The contrast between conditions and its confidence interval are estimated at the level of independent experimental units.

Different experimental conditions. The analysis reports means, standard errors, t-tests and analysis of variance. It does not estimate the proposed donor-level spatial-treatment contrast with a confidence interval.

The aged niche disrupts muscle stem cell quiescence (Materials and Methods, Statistics; Figures 2-5.)

The experiment does not distinguish the explanations if the intervention fails to separate the groups or if the confidence interval permits substantial effects in both directions.

Not verified in the article. The supplied studies do not apply the specified inconclusive-result rule based on failed exposure separation or confidence intervals permitting substantial effects of either sign.

A positive result would justify testing selective limitation of local FGF2 peaks; if the hypothesis is refuted, this approach does not proceed to the next stage.

Not verified in the article. The authors proposed reducing chronic niche FGF2 production or satellite-cell FGF signaling. Selective spatial-peak limitation contingent on the proposed experiment and its stopping rule was not tested or specified.

The aged niche disrupts muscle stem cell quiescence (Discussion, final paragraph.)

The experiment uses primary myotubes in paired cultures from young and older donors, with the central hypothesis concerning recovery in cells from older donors.

Different experimental conditions. The age-related muscle experiments used primary mouse myoblasts pooled from animals aged 1 through 6 months. They did not use paired primary myotube cultures from young and older human donors.

Reactive oxygen species stress increases accumulation of tyrosyl-DNA phsosphodiesterase 1 within mitochondria (Results, Figure 5a-c; Materials and Methods, Animal subjects.)

Cultures must have equal initial burdens of covalent mitochondrial topoisomerase I (TOP1MT) complexes, and exposure to the damage source must then be stopped.

Not verified in the article. Drug removal and subsequent DNA recovery were examined, but equal initial TOP1MT-complex burdens were not established. Complex burdens differed between TDP1 genotypes.

SCAN1-TDP1 trapping on mitochondrial DNA promotes mitochondrial dysfunction and mitophagy (Results, Figures 1C-D and 2D-E; Materials and Methods, Quantification of mtDNA damage.)

The proposed intervention briefly restores mitochondrial tyrosyl-DNA phosphodiesterase 1 (TDP1) immediately after removal of the damage source.

Different experimental conditions. The study used inducible TDP1 depletion and complementation with RNA-interference-resistant human TDP1, with expression induced for 24 to 48 hours. It did not apply a brief mitochondrial restoration pulse immediately after damage-source removal.

Mitochondrial protein-linked DNA breaks perturb mitochondrial gene transcription and trigger free radical-induced DNA damage (Results, Figure 1A,E; Materials and Methods, Cell lines and plasmids.)

Randomized experimental groups compare mitochondrially targeted active TDP1, a catalytically inactive variant, and delayed delivery of equal activity.

Different experimental conditions. The comparison used wild-type TDP1, TDP1 deficiency, and H493R, which retains partial activity and forms toxic DNA adducts. This differs from an inactive control, and the randomized immediate-versus-delayed equal-activity comparison is absent.

SCAN1-TDP1 trapping on mitochondrial DNA promotes mitochondrial dysfunction and mitophagy (Introduction; Results, Figure 1; Materials and Methods, Cell culture, plasmids, and generation of stable cell lines.)

Mitochondrial localization of the delivered TDP1 must be confirmed.

Matches this study. Cell fractionation and immunoblotting confirmed mitochondrial localization of introduced FLAG-tagged wild-type and H493R TDP1. This establishes the localization component in mouse fibroblasts, rather than the proposed myotube pulse experiment.

SCAN1-TDP1 trapping on mitochondrial DNA promotes mitochondrial dysfunction and mitophagy (Results, Mitochondria harboring SCAN1 mutant TDP1 (H493R) are hypersensitive to mitochondria-targeted Top1 poison; Figure 1A.)

TDP1 removes protein-linked mitochondrial DNA breaks, whose accumulation has been associated in cellular models with impaired mitochondrial transcription and respiration.

Matches this study. TDP1 depletion increased mitochondrial TOP1-linked breaks, reduced mitochondrial transcript abundance, and impaired respiratory function. Complementation partially rescued transcript levels. The central repair component is reported, although transcription and respiration responded differently under excessive TOP1MT trapping.

Mitochondrial protein-linked DNA breaks perturb mitochondrial gene transcription and trigger free radical-induced DNA damage (Results, Figures 1B-I, 2 and 3; Discussion, Figure 6.)

Repair of existing mitochondrial DNA templates is proposed to restore transcription before selection of organelles and replacement of damaged mitochondria.

Not verified in the article. The supplied studies do not establish that repaired pre-existing DNA templates resume transcription before organelle selection or replacement.

The alternative explanation is that the overall benefit results from selective removal of organelles with defective genomes.

Different experimental conditions. Mitophagy and a protective role of autophagy were demonstrated in models expressing DNA-trapping H493R TDP1. Selective clearance was not tested as the explanation for transcriptional benefit after acute TDP1 restoration in older myotubes.

SCAN1-TDP1 trapping on mitochondrial DNA promotes mitochondrial dysfunction and mitophagy (Results, Figures 5E-H and 6; Discussion.)

The time course of covalent TOP1MT complexes, mitochondrial DNA copy number, and mitophagy flux must be measured.

Not verified in the article. The study measured TOP1MT complexes, mitochondrial DNA-related quantities, and reporter-based mitophagic flux in separate experiments. It did not provide the specified coordinated post-exposure time course during immediate and delayed TDP1 restoration.

SCAN1-TDP1 trapping on mitochondrial DNA promotes mitochondrial dysfunction and mitophagy (Results, Figures 1C-D, 2C-E and 6A-C.)

The primary outcome is newly synthesized mitochondrial RNA per DNA copy at 6 hours.

Different experimental conditions. The outcome was total mitochondrial transcript abundance normalized to GAPDH RNA. It was not newly synthesized mitochondrial RNA per DNA copy at 6 hours.

Mitochondrial protein-linked DNA breaks perturb mitochondrial gene transcription and trigger free radical-induced DNA damage (Figure 1D-F,I; Materials and Methods, Mitochondrial gene transcription; Statistical analyses.)

The donor is the unit of analysis.

Different experimental conditions. The muscle experiments used pooled material from eight mice and reported experimental replicates. Individual human donors were not the units of analysis.

Reactive oxygen species stress increases accumulation of tyrosyl-DNA phsosphodiesterase 1 within mitochondria (Figure 5a-c; Materials and Methods, Statistical analysis.)

A reduction in covalent complexes accompanied by early recovery of transcription before replacement of the organelle population would support the proposed repair mechanism.

Not verified in the article. Complex resolution and TDP1-dependent transcript levels were linked experimentally, but recovery before organelle population replacement was not demonstrated.

Mitochondrial protein-linked DNA breaks perturb mitochondrial gene transcription and trigger free radical-induced DNA damage (Results, Figure 1B-I; Discussion.)

A delayed pulse of equal TDP1 activity is predicted to produce weaker transcriptional recovery than immediate restoration.

Not verified in the article. No supplied study compared immediate and delayed TDP1 pulses with equal activity or demonstrated weaker transcriptional recovery after delayed delivery.

If the complexes disappear but a substantial improvement in transcription is excluded, the proposed mechanism is insufficient.

Not verified in the article. No supplied experiment applies the proposed falsification criterion of complex disappearance together with exclusion of a substantial transcriptional improvement.

Different initial damage burdens or loss of organelles make the experiment uninformative.

Not verified in the article. Comparable mitochondrial DNA copy numbers helped interpret complex measurements, but did not establish equal initial damage or exclude organelle loss and replacement during recovery.

Mitochondrial protein-linked DNA breaks perturb mitochondrial gene transcription and trigger free radical-induced DNA damage (Results, Figure 1C and description of Figure S2C.)

The conclusion is restricted to recovery of transcription.

Different experimental conditions. The published conclusions extend to respiratory-chain assembly, oxygen consumption, radical damage, and survival. They do not represent the proposed inference restricted to early transcriptional recovery.

Mitochondrial protein-linked DNA breaks perturb mitochondrial gene transcription and trigger free radical-induced DNA damage (Results, Figures 1-5; Discussion.)

The comparison with mitochondrial DNA ligase III (LIG3) states that LIG3 is beneficial while the original circular DNA molecule remains repairable.

Not verified in the article. Mitochondrial interaction between TDP1 and ligase III was demonstrated. The conditional benefit of LIG3 while the original circular DNA molecule remains repairable was not tested.

Reactive oxygen species stress increases accumulation of tyrosyl-DNA phsosphodiesterase 1 within mitochondria (Results, Mitochondrial Tdp1 interacts with BER constituents and maintains mtDNA integrity; Figure 2a,g.)

The timing at which repair of individual molecules can still restore function in an old cell remains unresolved, and results of the proposed experiment have not been obtained.

Not verified in the article. The supplied studies do not determine the effective molecular-repair window in older donor myotubes or report results of the complete proposed experiment. This limits the conclusion to the supplied literature.

The experiment tests a proposed mechanism of age-related thymic involution using organotypic slices of old and young thymus.

Different experimental conditions. Young and aged mouse thymi were compared at baseline and after irradiation in vivo. Tissue sections were used for imaging, rather than living organotypic slices subjected to the proposed experiment.

Age-related epithelial defects limit thymic function and regeneration (Results, Figures 1-6; Methods, Tissue collection and Thymic tissue clearing and immunofluorescence.)

The mechanistic rationale is that, after experimental thymic injury, endothelial BMP4 supports the thymic epithelium through FOXN1 and associated signals.

Not verified in the article. The article cites the endothelial BMP4 regeneration study and measures injury-associated Bmp4 and epithelial Foxn1 responses. The cited primary study is absent as a supplied full article, so the complete endothelial BMP4-to-FOXN1 causal mechanism cannot be verified from its own experiments here.

Age-related epithelial defects limit thymic function and regeneration (Results, aaTECs co-opt growth signals at baseline and during repair, Figure 6; reference 31.)

A local BMP4 pulse in the old thymus is proposed to increase new T-cell output when lymphoid progenitors subsequently enter while epithelial DLL4 remains elevated.

Not verified in the article. No supplied experiment links a local BMP4 pulse in aged thymus to progenitor arrival during elevated epithelial DLL4 and subsequently increased new T-cell output.

The benefit of this temporal coincidence is predicted to be greater in old stroma with a short interval of high DLL4 than in young stroma.

Not verified in the article. Aged mice showed impaired regeneration and loss of injury-induced Dll4 upregulation. These observations establish neither a shorter high-DLL4 interval nor a greater benefit from synchronized progenitor entry.

Age-related epithelial defects limit thymic function and regeneration (Results, Figures 5-6, especially Figure 6b.)

Old and young thymic organotypic slices must receive the same BMP4 pulse.

Not verified in the article. Identical BMP4 pulses administered to old and young organotypic thymic slices are absent from the supplied experiments.

Labeled lymphoid progenitors must be added after the BMP4 pulse either at the peak of epithelial DLL4 or after its decline.

Not verified in the article. No supplied study adds labeled lymphoid progenitors at an experimentally established epithelial DLL4 peak versus after its decline following BMP4 exposure.

The comparison of young and old stroma must use progenitors of the same donor age, with labeled progenitors drawn from the same donor batch.

Different experimental conditions. Progenitors from the same cord blood donor were compared in artificial organoids and OP9-DL1 monolayers. This is a different culture comparison, without labeled same-batch progenitors applied to old and young thymic stroma.

Generation of mature T cells from human hematopoietic stem/progenitor cells in artificial thymic organoids (Figure 2 legend; Online Methods, Artificial Thymic Organoid cultures and T cell monolayer co-cultures.)

BMP4 treatment must be compared with vehicle controls at both progenitor-addition times in old and young thymic slices.

Not verified in the article. Vehicle controls at both DLL4-defined progenitor-addition times in both old and young BMP4-treated slices are absent.

The number of progenitors that actually enter the slices must be equalized across the experimental comparisons.

Not verified in the article. Equalization of progenitors that actually enter thymic slices is not reported. Defined seeding numbers in artificial organoids do not verify this entry control.

FOXN1 must be suppressed in the epithelium to test the proposed mechanism.

Different experimental conditions. A Foxn1 hypomorphic mouse model and computational perturbations tested age-associated epithelial differentiation. Epithelial FOXN1 suppression was not incorporated into a BMP4-pulse/progenitor-timing slice experiment.

Age-related epithelial defects limit thymic function and regeneration (Results, Reduction in FOXN1 activity favors aaTEC differentiation, Figure 7g-h.)

The primary outcome must be the number of donor-derived mature TCRβ-high single-positive CD4 or CD8 cells exiting the slice, measured at the same interval after progenitor addition; entry at peak epithelial DLL4 is predicted to yield more of these cells than entry after DLL4 declines.

Different experimental conditions. The study quantified mature CD3+TCRαβ+ CD4 or CD8 single-positive cells recovered by organoid disruption and explicitly described absent T-cell egress. It did not measure donor-derived TCRβ-high cells exiting slices after DLL4-timed entry at equal follow-up intervals.

Generation of mature T cells from human hematopoietic stem/progenitor cells in artificial thymic organoids (Results, Figures 1-4; Discussion; Online Methods, Artificial Thymic Organoid cultures.)

An increase in thymic mass alone does not establish increased output of new mature T cells.

Matches this study. The study explicitly distinguishes thymic enlargement from functional regeneration and separately evaluates recent thymic emigrants and T-cell receptor excision circles. This supports the requirement for output evidence beyond organ size.

Regeneration of the aged thymus by a single transcription factor (Results, FOXN1-mediated thymus regeneration impacts the peripheral immune system by increasing naive T cell numbers, Figure 5; Discussion.)

Equal benefit at the two progenitor-addition times despite different epithelial DLL4 levels would refute the timing hypothesis.

Not verified in the article. No supplied study compares the treatment benefit at the two specified addition times despite verified differences in epithelial DLL4, so the proposed refutation criterion has not been tested.

The proposed test concerns previously damaged 26S proteasomes in old hepatocytes.

Different experimental conditions. The starvation experiments used lung fibroblasts and other mammalian cell models, rather than old hepatocytes containing previously damaged 26S proteasomes.

Starvation-induced proteasome assemblies in the nucleus link amino acid supply to apoptosis (Results, Figures 1-4; Methods, Cell culture.)

Increasing removal of previously damaged 26S proteasomes after nutrient deprivation is predicted to accelerate proteolysis only when assembly of new replacement complexes is simultaneously available.

Not verified in the article. No supplied experiment tests whether enhanced removal of damaged proteasomes after nutrient deprivation accelerates proteolysis specifically when replacement assembly is available.

When assembly of new complexes is limited, increased removal of previously damaged 26S proteasomes is predicted to prolong the functional deficit.

Not verified in the article. No supplied study measures whether enhanced removal prolongs the functional deficit when assembly of replacement complexes is limited.

The experimental rationale links proteasome autophagy during starvation with proteasome recovery through NFE2L1, while their joint contribution to replacement of old complexes after damage remains unestablished.

Not verified in the article. The study supports NFE2L1 activation and compensatory proteasome gene expression after inhibition. Starvation-induced proteasome autophagy appears as cited background in the supplied literature; its joint contribution with NFE2L1 to replacement after damage is untested.

The aspartyl protease DDI2 activates Nrf1 to compensate for proteasome dysfunction (Introduction; Results and discussion, Figure 3D-E.)

Old proteasome subunits must be labeled separately from new subunits.

Different experimental conditions. Fluorescently tagged proteasome subunits were used to track localization and exchange, but the labeling did not distinguish old subunits from newly synthesized subunits.

Starvation-induced proteasome assemblies in the nucleus link amino acid supply to apoptosis (Results, Figures 1f and 6e; Methods, Plasmids.)

Damage in the old labeled fraction must be verified with a functional assay.

Not verified in the article. Substrate accumulation after inhibition and an activity probe supported proteasome activity during starvation. These assays did not verify damage in an age-labeled old fraction.

Starvation-induced proteasome assemblies in the nucleus link amino acid supply to apoptosis (Results, Figure 10a-b.)

A factorial experiment must vary targeted delivery of labeled proteasome complexes to lysosomes and NFE2L1 activity in combination.

Not verified in the article. No supplied study factorially combines targeted lysosomal delivery of labeled proteasome complexes with manipulation of NFE2L1 activity.

Overall autophagic flux must be controlled in the experiment.

Not verified in the article. Chloroquine and 3-methyladenine were used to inhibit autophagy and examine condensates and survival. This does not establish control of overall autophagic flux in the proposed replacement experiment.

Starvation-induced proteasome assemblies in the nucleus link amino acid supply to apoptosis (Results, Figure 9d-f and Supplementary Figure 9e-f.)

Degradation of free proteasome subunits must be controlled in the experiment.

Not verified in the article. Partitioning nascent subunits between degradation and assembly is explicitly speculative. Replotted turnover data from another study do not provide the required experimental control of free-subunit degradation.

Early recovery of proteasome activity in cells pulse-treated with proteasome inhibitors is independent of DDI2 (Ideas and speculations, Figure 4; Author response.)

The primary outcome must be the half-life of an independent proteasomal substrate measured after nutrient restoration.

Different experimental conditions. The outcome was recovery of β5 catalytic activity after proteasome-inhibitor washout, rather than the half-life of an independent proteasomal substrate after nutrient restoration.

Early recovery of proteasome activity in cells pulse-treated with proteasome inhibitors is independent of DDI2 (Results, Figures 1-3; Methods, Proteasome activity assays.)

The decisive comparison must assess the relationship between increased removal and substrate clearance under conditions with markedly different, experimentally verified assembly of new 26S proteasomes.

Not verified in the article. Cycloheximide established a requirement for protein synthesis during activity recovery. The study did not verify contrasting levels of new 26S assembly or relate them to enhanced removal and substrate clearance.

Early recovery of proteasome activity in cells pulse-treated with proteasome inhibitors is independent of DDI2 (Results, Figure 3; Ideas and speculations, Figure 4.)

The proposed dependence must be rejected if the relationship between increased removal and substrate clearance retains the same direction despite the verified marked difference in assembly of new 26S proteasomes.

Not verified in the article. No supplied experiment applies the specified rejection criterion by comparing the direction of the removal effect across experimentally verified assembly conditions.

The hypothesis concerns replication fork stalling in a guanine-rich region during epithelial aging and is to be tested in organoids.

Different experimental conditions. Defined guanine-rich replication barriers were studied using plasmids in Xenopus laevis egg extracts. This substitutes a cell-free amphibian system for organoids modeling epithelial aging.

FANCJ promotes DNA synthesis through G-quadruplex structures (Results, Figures 3-5; Materials and Methods, Xenopus egg extract and replication of ssDNA plasmids.)

FANCJ helicase is to be transiently restored after confirmed replication fork stalling.

Different experimental conditions. Recombinant FANCJ was added after 60 minutes, when stalled products were demonstrably present, and rescue was assessed after another 30 minutes. Post-stalling restoration was therefore tested, but through protein addition to depleted extract rather than transient restoration in organoids.

FANCJ promotes DNA synthesis through G-quadruplex structures (Results, Depletion of FANCJ causes persistent replication stalling at G-quadruplex structures; Figure 5C.)

FANCJ helicase activity after fork stalling is proposed to reduce deletions during replication restart, with the effect expected only at sequences capable of forming a G-quadruplex.

Not verified in the article. FANCJ addition relieved established stalling at a G-quadruplex, but a reduction in deletions caused by post-stalling rescue was not demonstrated. Sequenced products showed no mutations or deletions even after FANCJ depletion, so the proposed deletion-prevention link remains unverified.

FANCJ promotes DNA synthesis through G-quadruplex structures (Results, Figure 5C and sequencing results associated with Supplementary Figure S5; Discussion.)

The experiment must compare paired reporters containing a G-quadruplex-forming sequence and a sequence that disrupts G-quadruplex formation.

Different experimental conditions. The study compared defined G-quadruplex substrates with sequence-disrupted controls, including GGGAGGGTGGGAGGG versus GGGACCCTGGGAGGG. These were replication substrates in egg extracts, rather than paired cellular reporters in organoids.

Multistep mechanism of G-quadruplex resolution during DNA replication (Results, Figures 1-2 and Supplementary Figure S1; Materials and Methods, Preparation of plasmid substrates.)

The paired reporters must have matched baseline transcription levels.

Not verified in the article. None of the supplied studies verifies matched baseline transcription between the proposed paired G-quadruplex-forming and G-quadruplex-disrupting reporters.

FANCJ must be compared with a FANCJ variant lacking helicase activity.

Matches this study. FANCJ-knockout HeLa cells were complemented with wild-type FANCJ or helicase-inactive K52R. Wild-type FANCJ rescued replication phenotypes, whereas K52R did not, directly implementing the requested catalytic control.

MutSβ-MutLβ-FANCJ axis mediates the restart of DNA replication after fork stalling at cotranscriptional G4/R-loops (Results, Replication restart at R-loop-stalled forks requires the helicase activity of FANCJ; Figure 8A-C.)

The primary outcome is the fraction of molecules that are fully and accurately copied after fork stalling.

Different experimental conditions. The study measured stalled and bypassed products, observed fully replicated plasmids, and separately sequenced recovered products for fidelity. It did not determine the specified joint fraction of fully and accurately copied molecules after transient post-stalling FANCJ restoration.

FANCJ promotes DNA synthesis through G-quadruplex structures (Results, Figures 3 and 5; G4 sequences are not mutated after replication in Xenopus egg extract; Supplementary Figure S5.)

Additional outcomes are deletions and reporter loss.

Different experimental conditions. The study measured loss of Bu1a expression and examined loci for deletions, finding evidence for epigenetic silencing. This differs from measuring deletions and physical reporter loss after the proposed post-stalling intervention.

FANCJ coordinates two pathways that maintain epigenetic stability at G-quadruplex DNA (Results, Figure 5A-B; Epigenetic instability in fancj mutants; Supplementary Figures S4-S5.)

The proposed specific recovery mechanism is unsupported if only the frequency of initial fork stalls changes.

Not verified in the article. Similar early stalling kinetics with and without FANCJ, followed by persistent stalling after depletion and rescue by delayed addition, already distinguish recovery from initial barrier formation. However, the specified rejection criterion was not evaluated for accurate copying and deletion reduction in the proposed organoid test.

FANCJ promotes DNA synthesis through G-quadruplex structures (Results, Depletion of FANCJ causes persistent replication stalling at G-quadruplex structures; Figure 5B-C.)

The proposed specific recovery mechanism is unsupported if the result is the same when G-quadruplex formation is disrupted.

Not verified in the article. Control substrates showed that helicase depletion selectively impaired G-quadruplex replication. The study did not test whether disrupting G-quadruplex formation abolishes the deletion-reducing effect of transient FANCJ restoration after confirmed stalling.

Multistep mechanism of G-quadruplex resolution during DNA replication (Results, FANCJ and DHX36 are required for efficient G4 structure unwinding; Supplementary Figure S1G-H; Figure 2.)

The proposed experiment uses a preclinical animal model to compare old and young kidneys, with both age groups receiving the same injury regimens.

Matches this study. Young and aged C57BL/6 mice received the same 25-minute bilateral renal ischemia regimen. This matches the age comparison under a common injury regimen, although the study used a single injury.

Impact of aging on transition of acute kidney injury to chronic kidney disease (Materials and Methods: Experimental animals and renal ischemia-reperfusion injury; Figures 1 and 7.)

In an aging kidney, recovery of overall filtration may conceal a residual defect in proximal tubular transport, even when creatinine has returned to baseline.

Not verified in the article. Creatinine returned to baseline despite persistent tubular abnormalities and fibrosis in young mice. Residual proximal transport impairment after exogenously verified filtration recovery in aging kidneys was not measured.

NLRP3 associated with chronic kidney disease progression after ischemia/reperfusion-induced acute kidney injury (Results: Severe ischemic AKI caused renal maladaptive repair with fibrosis; Figure 1; Methods: Renal function and NLRP3 measurement.)

Residual impairment of proximal transport after filtration recovery marks continued tubular vulnerability, during which a second injury increases the risk of persistent tubular injury and fibrosis.

Not verified in the article. Repeated ischemia increased tubular injury and fibrosis, but susceptibility was not linked to a measured residual transport defect after filtration recovery.

Ischemic Duration and Frequency Determines AKI-to-CKD Progression Monitored by Dynamic Changes of Tubular Biomarkers in IRI Mice (Results: Repeated Episodes of Moderate IRI Accelerated Kidney Injury in Mice; Figures 6 and 7.)

The hypothesis tests whether recovery of proximal transport marks the end of the vulnerable period better than elapsed time alone.

Not verified in the article. None of the supplied studies compared transport recovery with elapsed time as indicators of the end of vulnerability to a second injury.

Filtration must be measured using an exogenous marker, and transport must be assessed with adjustment for the filtered load.

Not verified in the article. Filtration was measured using exogenous FITC-sinistrin, but proximal transport adjusted for filtered load was not assessed, leaving the combined measurement requirement incomplete.

Impact of aging on transition of acute kidney injury to chronic kidney disease (Materials and Methods: Transdermal glomerular filtration rate measurement.)

After the first injury episode, one experimental group receives a second injury episode once filtration has recovered.

Different experimental conditions. The second 30-minute ischemic episode occurred after a fixed seven-day interval, rather than being triggered by documented filtration recovery; creatinine remained elevated at this time in the corresponding single-injury model.

Ischemic Duration and Frequency Determines AKI-to-CKD Progression Monitored by Dynamic Changes of Tubular Biomarkers in IRI Mice (Results: Repeated Episodes of Moderate IRI Accelerated Kidney Injury in Mice; Figure 6; Supplementary Figure S1B description.)

After the first injury episode, another experimental group receives a second injury episode after proximal transport has recovered in the individual animal.

Not verified in the article. No supplied study administered a second injury after documenting proximal transport recovery in the individual animal.

The repeated-injury groups must be compared with a control group in which other animals are assigned calendar intervals with the same distribution as the individually determined transport-recovery intervals, without using the recipient animal's recovery state to determine its interval.

Not verified in the article. No supplied study assigned other animals intervals drawn from the same distribution as individual transport-recovery times independently of each recipient's recovery state.

Additional control groups must receive single injuries at the corresponding times.

Not verified in the article. A single-injury comparator was included, but single injuries at the corresponding times of all proposed recovery-guided and calendar-matched schedules were not documented.

Ischemic Duration and Frequency Determines AKI-to-CKD Progression Monitored by Dynamic Changes of Tubular Biomarkers in IRI Mice (Results: Repeated Episodes of Moderate IRI Accelerated Kidney Injury in Mice; Figure 6.)

The comparison must account for the administered dose and blood supply, without retrospectively equalizing the biological response.

Not verified in the article. Ischemia duration was specified and reperfusion was visually confirmed. These procedures do not establish the proposed comparison of administered exposure and blood supply across recovery states while preserving biological-response differences.

Ischemic Duration and Frequency Determines AKI-to-CKD Progression Monitored by Dynamic Changes of Tubular Biomarkers in IRI Mice (Materials and Methods: Animal Models; Results: Repeated Episodes of Moderate IRI Accelerated Kidney Injury in Mice.)

The primary outcome is the fraction of interstitial fibrosis measured four weeks after the last exposure.

Different experimental conditions. The repeated-injury experiment used an ordinal fibrosis score at day 14 after the first injury, seven days after the second. This differs from the primary fibrosis fraction measured four weeks after the last exposure.

Ischemic Duration and Frequency Determines AKI-to-CKD Progression Monitored by Dynamic Changes of Tubular Biomarkers in IRI Mice (Methods: Histology and Quantitative Assessment of Tubular Injury and Fibrosis; Figure 6A-B.)

Waiting for individual transport recovery is predicted to reduce interstitial fibrosis more than waiting for matched calendar intervals without accounting for the individual animal's state.

Not verified in the article. The supplied studies provide no fibrosis comparison between individualized transport-recovery waiting and calendar-matched waiting.

The critical test of the role of aging compares the effect of the individually selected interval on fibrosis in old versus young animals.

Not verified in the article. The study compared fibrosis between young and aged mice after one injury, but did not compare the effect of individually selected reinjury intervals between ages.

Impact of aging on transition of acute kidney injury to chronic kidney disease (Results: Persistent M1-predominant inflammation is associated with progressive fibrosis after ischemia-reperfusion injury; Figure 7.)

An additional analysis assesses filtration again after a recovery period.

Matches this study. Filtration was measured longitudinally in the same animals before injury and at day 28, matching the component requiring reassessment after a recovery period.

Impact of aging on transition of acute kidney injury to chronic kidney disease (Figure 7A and legend; Discussion; Methods: Transdermal glomerular filtration rate measurement.)

If waiting for transport recovery offers no advantage over waiting the same duration without accounting for the individual animal's state, the additional role of transport recovery as a marker is refuted.

Not verified in the article. The proposed falsification criterion was not tested because no supplied study compared individualized transport-guided waiting with equally long waiting independent of the animal's state.

Differences confined to creatinine do not establish long-term tubular injury.

Matches this study. The study established persistent tubular injury and fibrosis histologically despite normalized creatinine, explicitly demonstrating why creatinine alone cannot characterize long-term tubular injury.

NLRP3 associated with chronic kidney disease progression after ischemia/reperfusion-induced acute kidney injury (Results: Severe ischemic AKI caused renal maladaptive repair with fibrosis; Figures 1 and 3; Discussion.)

The experiment is proposed, and its results have not yet been obtained.

Not verified in the article. The submitted record describes an experiment awaiting results. No supplied publication reports that exact experiment; its proposed status is contextual and does not independently establish scientific novelty.

Age dependence of the response to T4N5 is to be assessed in paired series of cells from young and elderly donors.

Different experimental conditions. Hu and colleagues used an immortalized newborn-derived fibroblast line and mutant fibroblast lines, rather than paired young and elderly donor series receiving T4N5.

Genome-wide analysis of human global and transcription-coupled excision repair of UV damage at single-nucleotide resolution (Materials and methods: Cell lines.)

In elderly donors, the response to T4N5 is hypothesized to depend on whether repair is limited by damage recognition or completion of ligation.

Not verified in the article. The supplied studies do not compare T4N5 responses under recognition and ligation limitations in elderly donor cells.

The greatest benefit of the bypass enzyme T4N5 in aged skin is predicted with partial loss of cyclobutane pyrimidine dimer (CPD) recognition and preserved ability to complete repair after incision.

Not verified in the article. Preferential benefit in aged skin with partial CPD recognition loss and preserved post-incision repair completion is not tested in the supplied literature.

When damage recognition limits repair, T4N5 is predicted to restore barrier reserve.

Not verified in the article. The clinical report assesses new skin lesions; it does not establish restoration of barrier reserve specifically under recognition limitation.

When ligation limits repair, T4N5 is predicted to leave residual breaks and produce a weak functional response.

Not verified in the article. The ligase study measures recruitment to damage sites, not residual breaks and functional weakness following T4N5 treatment under ligation limitation.

XPC or ligating activity is to be reduced separately in isogenic cultures to establish the two repair limitations.

Different experimental conditions. The study compares normal, XP-C and CS-B fibroblast lines to separate repair pathways. It does not separately reduce XPC and ligating activity in isogenic cultures.

Genome-wide analysis of human global and transcription-coupled excision repair of UV damage at single-nucleotide resolution (Results: Genetic separation of transcription-coupled and global excision repair reveals distinct genome-wide patterns; Materials and methods: Cell lines.)

T4N5 treatment and an inactive control are to be tested under each repair limitation.

Different experimental conditions. Patients received T4N5 liposome lotion or placebo liposome lotion. This comparison lacks the two experimentally established repair limitations and does not specify an inactive-enzyme control.

Effect of topically applied T4 endonuclease V in liposomes on skin cancer in xeroderma pigmentosum: a randomised study (Abstract: Methods.)

Both CPDs and unsealed single-strand breaks are to be measured after enzyme washout.

Different experimental conditions. The study measures excised CPD-containing oligonucleotides after irradiation. It does not jointly measure remaining CPDs and unsealed single-strand breaks after T4N5 washout.

Genome-wide analysis of human global and transcription-coupled excision repair of UV damage at single-nucleotide resolution (Results: The XR-seq procedure; Figure 1; Materials and methods: Purification and detection of excision products.)

The initial ultraviolet dose must be the same for the comparison of functional outcomes.

Not verified in the article. Cells received the same 20 J/m² ultraviolet dose for excision analyses, but the required equal-dose comparison of functional outcomes under the two repair limitations is absent.

Genome-wide analysis of human global and transcription-coupled excision repair of UV damage at single-nucleotide resolution (Materials and methods: UV irradiation; Results: Characterization of nucleotide excision repair kinetics in wild-type and mutant cells.)

The primary outcome is the ability to produce viable epithelial colonies, with a greater improvement predicted under the recognition limitation than under the ligation limitation.

Different experimental conditions. The clinical outcomes are new actinic keratoses and basal-cell carcinomas, rather than viable epithelial colony formation or a comparison of benefit between recognition and ligation limitations.

Effect of topically applied T4 endonuclease V in liposomes on skin cancer in xeroderma pigmentosum: a randomised study (Abstract: Methods and Findings.)

An equal benefit from adding T4N5 under both repair limitations would refute the prediction.

Not verified in the article. No supplied study tests whether T4N5 provides equal functional benefit under the two repair limitations.

An increase only in the number of intermediate breaks after enzyme addition would refute the prediction.

Not verified in the article. No supplied study evaluates an isolated increase in intermediate breaks after T4N5 addition as the specified falsifying outcome.

The stated scientific basis includes a small randomized study of T4N5 in xeroderma pigmentosum, described as an inherited defect, in which new skin lesions were assessed.

Matches this study. The supplied abstract describes a randomized trial of 30 patients with an inherited repair defect, comparing T4N5 with placebo and assessing new actinic keratoses and basal-cell carcinomas. The full article is unavailable here.

Effect of topically applied T4 endonuclease V in liposomes on skin cancer in xeroderma pigmentosum: a randomised study (Abstract: Background, Methods and Findings.)

The stated scientific basis also includes measurements of ultraviolet damage excision across different genomic regions in human cells, with global and transcription-coupled excision repair named in the cited work.

Matches this study. Hu and colleagues mapped ultraviolet photoproduct excision across the human genome and separated global from transcription-coupled repair using normal, XP-C and CS-B fibroblasts.

Genome-wide analysis of human global and transcription-coupled excision repair of UV damage at single-nucleotide resolution (Results: Figures 2 and 3; Materials and methods: XR-seq assay.)

The experiment must use hepatocytes from old mice.

Different experimental conditions. The study examined livers from 22-month-old mice, but isolated primary hepatocytes came from mice aged 8-10 weeks. Its cultured-hepatocyte experiments therefore used a different age group.

Chaperone-mediated autophagy dysregulation during aging impairs hepatic fatty acid oxidation via accumulation of NCoR1 (Methods 2.1 and 2.4; Figures 1-3.)

LAMP2A must be induced to increase LAMP2A-mediated chaperone-mediated autophagy in hepatocytes subjected to lipid loading.

Different experimental conditions. LAMP2A re-expression and pharmacological activation of chaperone-mediated autophagy were tested in oleate-loaded NIH3T3 fibroblasts. This provides a related intervention, but substitutes fibroblasts for the required hepatocytes.

Degradation of lipid droplet-associated proteins by chaperone-mediated autophagy facilitates lipolysis (Results, Modifications of CMA-targeted PLINs; Figures 1g and 4a-b; Online Methods, Cell Culture and Treatments.)

Perilipin degradation gives lipases access to the lipid droplet, but the proposed improvement in functional recovery requires sufficient mitochondrial capacity to oxidize the released fatty acids; a reduction in lipid droplet size alone does not establish functional improvement when lipid oxidation is limited.

Not verified in the article. The experiments establish that perilipin removal facilitates lipase recruitment and lipid mobilization, and measure downstream oxidation. They do not establish that functional recovery after LAMP2A induction requires sufficient mitochondrial oxidation capacity.

Degradation of lipid droplet-associated proteins by chaperone-mediated autophagy facilitates lipolysis (Results, Defective CMA of PLINs blocks lipolysis; Figures 1c-d, 6 and 7.)

Fatty acids must be labeled before their incorporation into triglycerides.

Matches this study. Cells received radiolabeled [14C]-oleate, and its subsequent incorporation into triglycerides was measured after lipid extraction and thin-layer chromatography. This matches labeling fatty acids before triglyceride incorporation, although the complete proposed tracing experiment was not performed.

Degradation of lipid droplet-associated proteins by chaperone-mediated autophagy facilitates lipolysis (Online Methods, TG Synthesis; Figure 1b.)

LAMP2A induction must be compared under conditions of normal and partially reduced CPT1A.

Different experimental conditions. Etomoxir was used to inhibit mitochondrial fatty-acid uptake when comparing control and LAMP2A-deficient fibroblasts. This differs from comparing LAMP2A induction under normal and partially reduced CPT1A in hepatocytes.

Degradation of lipid droplet-associated proteins by chaperone-mediated autophagy facilitates lipolysis (Results, LAMP-2A-deficient cells accumulate LD; Figure 1d; Online Methods, Beta-oxidation.)

The experiment must include a PLIN2 variant resistant to degradation through the pathway under investigation while retaining its localization.

Matches this study. The PLIN2 targeting motif was mutated from 414 SLKVQ to 414 SLKAA. The mutant resisted lysosomal degradation and remained associated with lipid droplets, satisfying the resistant-variant and retained-localization requirement as a component.

Degradation of lipid droplet-associated proteins by chaperone-mediated autophagy facilitates lipolysis (Results, CMA-resistant PLIN2 causes steatosis; Figures 5b-h, 6j and 7i.)

The label must be measured in oxidized products and in toxic lipid fractions.

Not verified in the article. Radiolabeled carbon dioxide production and incorporation of label into triglycerides were measured. Measurement of label in toxic lipid fractions, alongside oxidized products in the proposed experiment, is absent.

Degradation of lipid droplet-associated proteins by chaperone-mediated autophagy facilitates lipolysis (Online Methods, Beta-oxidation and TG Synthesis; Figures 1b-c and 6a.)

The primary outcome must be recovery of albumin secretion after washout.

Not verified in the article. None of the supplied studies measured recovery of albumin secretion after lipid washout as the primary outcome. Related washout experiments assessed lipid droplets or cell viability.

The proposed causal sequence must be rejected if recovery of albumin secretion is equal at different levels of oxidation or is independent of PLIN2 turnover.

Not verified in the article. No supplied study tested whether equal albumin recovery across different oxidation levels, or recovery independent of PLIN2 turnover, rejects the proposed sequence.

The hypothesis concerns mitochondrial DNA (mtDNA) during the aging of postmitotic cells, and the experiment uses cells from young and elderly donors.

Different experimental conditions. The closest experiments used proliferating HEK 293 cells, including LIG3 knockout clones. They did not compare aging postmitotic cells from young and elderly donors.

Ligase 3 prevents oxidative strand break-induced mitochondrial DNA loss but is not essential for replicative circularization (Materials and methods, Cell growth conditions; Results, Figures 1-4.)

Old mtDNA molecules must be labeled before the experimental stresses so that original molecules can be distinguished from newly formed molecules.

Matches this study. Cells were labeled with bromodeoxyuridine for 24 hours, transferred to label-free medium and challenged with hydrogen peroxide. This explicitly tracks DNA labeled before stress separately from subsequent unlabeled synthesis.

Ligase 3 prevents oxidative strand break-induced mitochondrial DNA loss but is not essential for replicative circularization (Materials and methods, BrdU incorporation and decay experiments; Results, Figure 4A-B.)

The experiment must compare mitochondrially targeted active and inactive DNA ligase III (LIG3) after the experimental stresses.

Different experimental conditions. Mitochondrially targeted active Lig3 and inactive K508V Lig3 were compared for survival after endogenous Lig3 deletion. The inactive construct did not yield viable knockout clones, so it was not the matched comparator in the oxidative-damage repair experiment.

Crucial roles for DNA ligase III in mitochondria but not in XRCC1-dependent repair (Results, Figure 1b-c and Figure 2d; Full Methods, DNA constructs and qPCR mtDNA repair assay.)

The experiment must include stresses that produce predominantly single-strand breaks and stresses that produce predominantly double-strand breaks in mtDNA.

Different experimental conditions. Hydrogen peroxide produced both single-strand and double-strand breaks. The study did not compare separate predominantly single-strand-break and predominantly double-strand-break challenges within the proposed LIG3 restoration experiment.

Ligase 3 prevents oxidative strand break-induced mitochondrial DNA loss but is not essential for replicative circularization (Results, Figure 1A and Figure 2A; mtDNA in LIG3 knockout cells contains clusters of single-strand breaks.)

Mitochondrial LIG3 is proposed to be beneficial while an original circular mtDNA molecule remains repairable, allowing original molecules with single-strand breaks to return to a continuous circular form.

Matches this study. The study links LIG3 to sealing oxidative single-strand breaks and shows recovery of the prelabeled supercoiled mtDNA signal in wild-type cells, versus loss in LIG3-deficient cells. This supports the proposed repair mechanism as a component, without establishing the entire restoration experiment.

Ligase 3 prevents oxidative strand break-induced mitochondrial DNA loss but is not essential for replicative circularization (Results, Figures 1A, 2 and 4A-B; Discussion, first paragraph.)

Restoring mitochondrial LIG3 is predicted to preserve original mtDNA molecules with single-strand breaks more effectively than already linear mtDNA, for which little benefit is expected.

Not verified in the article. Rapid degradation of linearized mtDNA was demonstrated, but preferential preservation of original nicked circles over original linear molecules after LIG3 restoration was not tested. LIG3 knockdown also reduced fragment concatemers, indicating an end-joining role that must be distinguished from restoration of intact original genomes.

Linear mitochondrial DNA is rapidly degraded by components of the replication machinery (Results, Figures 1-2 and Figure 5c; Discussion.)

Linear, circular and newly formed mtDNA molecules must be measured separately.

Matches this study. Native-DNA blots distinguished open circular, full-length linear and supercoiled mtDNA. Separate bromodeoxyuridine incorporation and pulse-chase experiments assessed newly synthesized and previously labeled DNA. These measurement components are already present, although outside the proposed donor and intervention comparisons.

Ligase 3 prevents oxidative strand break-induced mitochondrial DNA loss but is not essential for replicative circularization (Results, Figure 1A and 1C-E; Figure 4A-B.)

The primary outcome must be the fraction of original labeled mtDNA molecules that return to a continuous circular form.

Different experimental conditions. Reappearance of the prelabeled supercoiled band was observed, but the quantified endpoint was decay of mitochondrial labeling. The fraction of original labeled molecules restored to continuous circles was not specified and quantified as the primary outcome.

Ligase 3 prevents oxidative strand break-induced mitochondrial DNA loss but is not essential for replicative circularization (Results, Figure 4A-C and accompanying text.)

Degradation of original mtDNA copies must be accounted for independently when evaluating restoration of the original labeled molecules.

Matches this study. The study separately assessed loss of prelabeled mtDNA, degradation-associated DNA ends and depletion during replication inhibition. Independent degradation assessment is therefore present, although it was not integrated into the proposed primary fraction; the baseline pulse-chase difference did not reach statistical significance.

Ligase 3 prevents oxidative strand break-induced mitochondrial DNA loss but is not essential for replicative circularization (Results, Figures 3 and 4A-D; Materials and methods, BrdU incorporation and decay experiments.)

Formation of new mtDNA molecules may conceal the difference in preservation of original molecules when only total mtDNA copy number is assessed.

Matches this study. LIG3-deficient cells maintained substantial copy numbers and synthesized circular mtDNA despite evidence of increased degradation. The authors explicitly interpret compensatory replication as maintaining copy number, supporting the concern that total abundance can conceal loss and replacement.

Ligase 3 prevents oxidative strand break-induced mitochondrial DNA loss but is not essential for replicative circularization (Results, Figures 1B-D and 4D; Discussion, Figure 6.)

An increase only in new mtDNA copies or survival, without restoration of original circular DNA, does not demonstrate improved repair.

Not verified in the article. No supplied study applies the complete proposed decision rule requiring restoration of original labeled circular genomes before interpreting improved copy number or survival as improved repair.

The experiment compares directly converted neurons from two age groups.

Different experimental conditions. The neuronal study describes cultured mouse cortical neurons and deletion in excitatory forebrain neurons in vivo. These differ from directly converted neurons compared across two age groups; the supplied abstract does not establish that comparison.

TDP2-mediated DNA repair regulates the dynamics of neuronal early response gene transcription and cortical neuron connectivity. (Abstract)

During neuronal aging, persistence of TOP2 protein remnants at DNA break ends may limit accurate joining.

Not verified in the article. TDP2 depletion delays repair of TOP2B-mediated breaks in mouse neurons, but the supplied text does not connect neuronal aging to persistent TOP2 remnants and reduced junction accuracy.

TDP2-mediated DNA repair regulates the dynamics of neuronal early response gene transcription and cortical neuron connectivity. (Abstract)

TDP2 removes the blocking TOP2 protein remnant from DNA break ends, which is proposed to enable accurate joining.

Matches this study. Biochemical detyrosylation assays, reconstituted joining, and cellular junction sequencing establish that TDP2 catalytic removal of the 5′-tyrosyl block enables efficient, more accurate joining. This mechanistic component is demonstrated outside the proposed aging-neuron system.

Reversal of DNA damage induced Topoisomerase 2 DNA–protein crosslinks by Tdp2 (Results, “Tdp2 facilitates NHEJ repair of 5′-phosphotyrosine adducted DSBs”; Figures 6C-D and 7A-D)

Restoring TDP2 is predicted to reduce specific rearrangements following TOP2 activity.

Matches this study. Restoring wild-type TDP2, unlike catalytic mutant D262A, reduces etoposide-induced chromosome translocations in TDP2-deficient RPE-1 cells. This matches the protective component, although the study also implicates TDP2 in a rare class of junctions with 4-bp homology.

TDP2 suppresses chromosomal translocations induced by DNA topoisomerase II during gene transcription (Results, “TDP2 suppresses TOP2-induced chromosome translocations”; Figure 4a-d)

Restoring TDP2 is expected to provide a greater benefit after TOP2 trapping on DNA than after a clean cut at a comparable locus.

Different experimental conditions. Adding recombinant TDP2 restores joining of phosphotyrosyl-blocked plasmid ends, whereas clean phosphorylated ends already join efficiently. This is a close biochemical comparison, but it substitutes artificial substrates and extracts for TOP2 trapping versus a clean cut at a comparable neuronal locus.

TDP2–Dependent Non-Homologous End-Joining Protects against Topoisomerase II–Induced DNA Breaks and Genome Instability in Cells and In Vivo (Results, “TDP2 creates ligatable DSBs and functions in NHEJ”; Figure 2D-E)

The experiment compares active and inactive TDP2 on both substrates with a 5′-phosphotyrosyl end and substrates with a clean end.

Not verified in the article. The study includes clean and tyrosylated substrates and tests catalytically deficient TDP2 on blocked-end joining. The supplied text does not verify the complete active-versus-inactive TDP2 comparison on both substrate types.

Reversal of DNA damage induced Topoisomerase 2 DNA–protein crosslinks by Tdp2 (Methods, “In vitro NHEJ reactions” and “Cellular NHEJ assays”; Figure 7A-D; Results describing Supplementary Figure S7A)

The experiment checks the initial TOP2 complexes.

Matches this study. The study measures TOP2-DNA complexes before washout and assesses initial lesion abundance and distribution. This control is present as a component in proteasome-inhibition experiments in mouse B cells, rather than in the proposed TDP2-restoration experiment.

Suppressing proteasome mediated processing of topoisomerase II DNA-protein complexes preserves genome integrity (Figures 1D and 2B-C, F; Methods, “In vitro of complex (ICE) Assay” and “Classification of TOP2-mediated DSBs”)

The experiment checks selection of surviving cells.

Not verified in the article. Clonogenic survival and an apoptosis check are reported, but they do not establish whether selective survival biases the final junction or rearrangement measurements. The proposed survivor-selection control is not verified.

TDP2 suppresses chromosomal translocations induced by DNA topoisomerase II during gene transcription (Figure 2a, d; Results, “TDP2 protects MLL from TOP2-induced breakage”; Methods, “Clonogenic survival assays”)

The main outcomes are removal of the blocking protein remnant and the fraction of accurate final junctions, with allele losses counted separately.

Not verified in the article. The study measures catalytic block removal, cellular joining efficiency, and junction error frequency on extrachromosomal substrates. Separate genomic allele-loss accounting, required alongside accurate final junctions, is absent from the supplied methods and results.

Reversal of DNA damage induced Topoisomerase 2 DNA–protein crosslinks by Tdp2 (Figures 6C-D and 7C-D; Methods, “Cellular NHEJ assays”)

If active TDP2 removes the protein remnant without increasing the yield of accurate junctions, a benefit in complete repair is not confirmed.

Not verified in the article. No supplied study explicitly evaluates the proposed failure criterion in the specified experiment: successful remnant removal by active TDP2 without an increased yield of accurate final junctions.

Apply a brief pulse of ALKBH3 after tRNA alkylation to test whether some pre-existing tRNA molecules in old cells regain function before replacement molecules are synthesized.

Different experimental conditions. The study used 2-hour treatment of isolated bovine tRNA and ALKBH3 knockdown in cancer cells, rather than a post-alkylation pulse in old cells with recovery assessed before replacement synthesis.

AlkB homolog 3-mediated tRNA demethylation promotes protein synthesis in cancer cells. (Figure 4A-E; Materials and Methods, ALKBH3-mediated RNA demethylation)

The proposed mechanism is that ALKBH3 removes chemical damage from pre-existing alkylated tRNA, allowing those same molecules to regain function.

Different experimental conditions. Demethylation of naturally modified bovine tRNA increased translation, but chemical-lesion repair restoring function in the same damaged molecules was not directly tested.

AlkB homolog 3-mediated tRNA demethylation promotes protein synthesis in cancer cells. (Results, ALKBH3-demethylated tRNA enhances in vitro protein translation efficiency; Figure 4A-B)

Distinguish repair of pre-existing damaged tRNA from the alternative explanation that increased translation is attributable solely to newly synthesized tRNA or demethylation of normal regulatory marks.

Not verified in the article. The isolated-tRNA experiment supports an effect of treated existing tRNA, but does not distinguish damage repair from normal-mark demethylation or track replacement synthesis in old cells.

AlkB homolog 3-mediated tRNA demethylation promotes protein synthesis in cancer cells. (Figure 4A-E; Discussion)

The stated biochemical basis is that AlkB and human ABH3 restored the ability of chemically methylated tRNA to be charged with an amino acid and participate in translation; whether this effect extends to old cells requires separate demonstration.

Not verified in the article. The discussion cites prior functional recovery of methylating-agent-treated bacterial tRNA by ALKBH3. The supplied 2004 page contains only a cookie notice, so its exact AlkB/ABH3 charging and translation experiments cannot be verified.

AlkB homolog 3-mediated tRNA demethylation promotes protein synthesis in cancer cells. (Discussion, paragraph citing Ougland et al.; References, Ougland et al. (2004))

Conduct the proposed experiment in primary cells from young and elderly donors.

Different experimental conditions. The systems were bovine tRNA, rabbit reticulocyte lysate, and the human pancreatic cancer cell line PANC-1, with no young-versus-elderly primary-cell comparison.

AlkB homolog 3-mediated tRNA demethylation promotes protein synthesis in cancer cells. (Materials and Methods, Reagents and cell culture; In vitro translation reaction and luciferase assay)

Introduce distinguishably labeled tRNA bearing a verified single chemical lesion together with paired undamaged tRNA.

Different experimental conditions. Commercial bovine tRNA with endogenous modifications was used, without introducing distinguishably labeled, single-lesion tRNA and its paired undamaged counterpart into cells.

AlkB homolog 3-mediated tRNA demethylation promotes protein synthesis in cancer cells. (Figures 2 and 4A-B; Materials and Methods, Reagents and cell culture)

Compare active ALKBH3, an inactive ALKBH3 variant, and an empty control.

Different experimental conditions. The study included mock treatment and heat-denatured enzyme in demethylation assays, but not the specified active-enzyme, inactive-variant, and empty-control comparison in primary cells.

AlkB homolog 3-mediated tRNA demethylation promotes protein synthesis in cancer cells. (Figure 1; Figure 4A-B)

Normalize delivery and integrity specifically for the introduced tRNA molecules.

Not verified in the article. The supplied literature does not report normalization of delivery and integrity for introduced labeled tRNA molecules.

The primary outcome is the fraction of pre-existing labeled tRNA charged with an amino acid after 2 hours.

Different experimental conditions. The 2-hour intervals concern isolated-RNA demethylation or nascent-protein labeling. Outcomes were luciferase activity and protein synthesis, not the charged fraction of pre-existing labeled tRNA at 2 hours.

AlkB homolog 3-mediated tRNA demethylation promotes protein synthesis in cancer cells. (Figure 4A-B and 4E; Materials and Methods, Quantification of nascent protein synthesis)

Independently confirm removal of the chemical modification from the introduced damaged tRNA.

Different experimental conditions. Mass spectrometry independently confirmed demethylation of isolated bovine tRNA, but not removal of a verified lesion from labeled damaged tRNA introduced into cells.

AlkB homolog 3-mediated tRNA demethylation promotes protein synthesis in cancer cells. (Figure 4A; Materials and Methods, LC-ESI-MS/MS analysis of nucleosides from RNA)

Check that there is no general shift in aminoacylation.

Not verified in the article. No supplied experiment checks whether general aminoacylation remains unchanged.

Restoration of amino acid charging in the same previously damaged tRNA molecules would support the hypothesis.

Not verified in the article. Increased translation was measured, while an effect on aminoacylation was suggested from earlier literature. Restored charging of the same previously damaged molecules was not measured.

AlkB homolog 3-mediated tRNA demethylation promotes protein synthesis in cancer cells. (Figure 4A-B; Discussion, paragraph addressing aminoacylation)

Removal of the damage mark without restoration of function in the same tRNA molecules, measured with sufficient precision, would refute the functional prediction.

Not verified in the article. The supplied literature does not test the specified refutation criterion of verified damage removal with precisely measured failure of functional recovery in the same tRNA molecules.

The artificial reporter does not establish that this pathway limits recovery of the whole organism.

Not verified in the article. The stated limit on whole-organism inference belongs to the proposal; the supplied study does not explicitly evaluate that reporter-based inference.

The scientific comparison is with the possibility that clearing ribosomes after oxidation restores translation fidelity; the proposed experiment instead tests functional restoration of a single pre-existing tRNA molecule, as distinct from removal or replacement of damaged ribosomes.

Not verified in the article. The supplied literature does not compare restoration of existing tRNA with clearance or replacement of oxidatively damaged ribosomes.

Results of the proposed experiment have not yet been obtained.

Not verified in the article. The proposal states that its results have not been obtained. This is its declared status, which the supplied literature does not independently establish.

The study tests a mechanism of age-related hearing decline by comparing old mice with young adult mice matched for the initial number of surviving hair cells.

Different experimental conditions. Cassinotti and colleagues compared acute responses in young and middle-aged mice and followed treated middle-aged mice into old age. This differs from initiating the proposed comparison in old versus young adults matched for initial surviving hair-cell counts; hair-cell histology was assessed at terminal sampling.

Cochlear Neurotrophin-3 overexpression at mid-life prevents age-related inner hair cell synaptopathy and slows age-related hearing loss (Results, Figures 1, 3, 5 and 6; Experimental procedures 4.1 and 4.4.)

The stated experimental basis is that local neurotrophin-3 (NT-3) promoted cochlear synapse restoration in mice after noise injury; whether restoration remains possible in the aged ear at different degrees of nerve-ending retraction is unresolved.

Matches this study. Local NT-3 delivery to the round window 24 hours after noise exposure promoted synaptic recovery in mice, establishing the stated experimental basis. The study used young mice and leaves restoration across retraction distances in aged ears unresolved.

Round-window delivery of neurotrophin 3 regenerates cochlear synapses after acoustic overexposure (Results, Synaptic loss and regeneration in the inner hair cell area, Figure 3; Methods, Animals and experimental design.)

NT-3 is proposed to restore the auditory synapse while the nerve process remains near the hair cell.

Not verified in the article. Hashimoto and colleagues proposed that terminal retraction could move Trk receptors away from the NT3 source in inner hair cells. This closely anticipates the spatial rationale, but proximity-dependent restoration was an explanatory hypothesis rather than an experimentally established condition.

Protection from noise-induced cochlear synaptopathy by virally mediated overexpression of NT3 (Discussion, Presence vs. absence of therapeutic effects.)

The benefit of NT-3 is proposed to depend on the initial distance between the surviving nerve ending and the inner hair cell.

Not verified in the article. The study examined terminal morphology after treatment and discussed spatial access to NT3. It did not measure each surviving ending's pretreatment distance and relate that distance to treatment benefit.

Protection from noise-induced cochlear synaptopathy by virally mediated overexpression of NT3 (Results, Effects of NT3 overexpression on noise-induced synaptopathy and hair cell loss, Figure 5; Discussion, Presence vs. absence of therapeutic effects.)

The initial nerve-ending-to-inner-hair-cell distance should predict restoration better than time since injury alone.

Not verified in the article. None of the supplied studies compared restoration predictions based on initial ending-to-cell distance with predictions based on time since injury alone.

The study should test whether the distance to the nerve ending explains the age-related difference in the response to NT-3.

Not verified in the article. The acute NT-3 response differed between young and middle-aged mice, but the authors discussed declining endogenous Ntf3 expression as an explanation. They did not test whether initial ending-to-cell distance explained the age difference.

Cochlear Neurotrophin-3 overexpression at mid-life prevents age-related inner hair cell synaptopathy and slows age-related hearing loss (Results, Figure 3; Discussion.)

After identical acoustic exposure, old mice should be allocated to NT-3 treatment or vehicle.

Different experimental conditions. Young CBA/CaJ mice received the same noise exposure followed by local NT-3 or poloxamer vehicle. The treatment and vehicle comparison is present, but the specified old-mouse population is replaced by young mice.

Round-window delivery of neurotrophin 3 regenerates cochlear synapses after acoustic overexposure (Methods, Animals and experimental design; Noise exposure.)

The culture experiment should use a paired cochlear culture.

Not verified in the article. No supplied primary study used the proposed paired cochlear culture. References to earlier explant experiments do not establish that paired design.

Nerve endings in the cochlear culture should be mapped before NT-3 exposure and subsequently tracked individually.

Not verified in the article. The supplied studies do not report pretreatment mapping followed by longitudinal tracking of individually identified endings in cochlear culture. Spatial analyses of fixed tissues from separate animals do not fulfill this requirement.

The primary culture outcome should be the proportion of initially disconnected endings in which an evoked postsynaptic current has been restored after 14 days.

Not verified in the article. No supplied study measured the proportion of initially disconnected cultured endings with restored evoked postsynaptic current after 14 days. Fourteen-day synaptic counts and whole-animal auditory responses in other experiments are different outcomes.

Comparisons in the living animal model should involve regions within the same frequency zone while controlling for outer hair cells and hearing thresholds.

Matches this study. The study compared corresponding cochlear frequency regions, including the 32-kHz lesion region, and assessed auditory thresholds, outer-hair-cell survival, and distortion-product otoacoustic emissions. These measurements address the specified frequency, outer-hair-cell, and threshold controls.

Round-window delivery of neurotrophin 3 regenerates cochlear synapses after acoustic overexposure (Results, Figures 1, 3, 5 and 6; Methods, Cochlear function testing; Synapse and hair cell counts.)

Wave I amplitude should be assessed in the animal model.

Matches this study. Suprathreshold auditory brainstem response wave I amplitude was measured and related to synaptic recovery in individual ears.

Round-window delivery of neurotrophin 3 regenerates cochlear synapses after acoustic overexposure (Results, Synaptic regeneration and functional recovery of suprathreshold responses, Figures 5 and 6; Methods, Cochlear function testing.)

Equal NT-3 benefit across all initial distance ranges at comparable viability would reject the prediction.

Not verified in the article. No supplied study compared NT-3 benefit across pretreatment distance ranges at comparable viability, so the specified rejection criterion was not evaluated.

After irradiation, salivary acid-neutralizing capacity may recover more slowly than salivary volume because an old duct may remain impaired in modifying salivary ionic composition even after acinar secretion has recovered.

Not verified in the article. The supplied studies do not establish delayed buffering recovery caused by persistent ductal impairment in old mice after acinar secretion recovers.

The competing explanation attributes weak buffering to flow rate, whereas the proposed separate ductal defect would leave a buffering deficit at a fixed flow rate.

Different experimental conditions. Healthy-human measurements support dissociation of stimulation-induced changes in flow and ionic composition. They do not test buffering deficits in irradiated mouse ducts at experimentally fixed flow.

Physiological regulation of oral saliva ion composition and flow rate are not coupled in healthy humans—Partial revision of our current knowledge required (Results, Stimulation of flow rate and changes in ion composition are not coupled; Fig. 5; Discussion)

The supporting observation in irradiated salivary glands of adult mice was that prolonged local delivery of cevimeline in a gel supported acinar regeneration and recovery of secretion compared with an injury control.

Matches this study. Local cevimeline in alginate promoted acinar replenishment and preserved secretion relative to irradiated controls. Sustained recovery used initial hydrogel delivery followed by repeated local cevimeline injections.

Long-term functional regeneration of radiation-damaged salivary glands through delivery of a neurogenic hydrogel (Results, Figs. 2-4; Materials and Methods, Periglandular application)

The supporting experiment in rat salivary gland ductal epithelium demonstrated active bicarbonate secretion, providing a basis for testing ductal function with a fixed supply of primary fluid.

Not verified in the article. The supplied text contains only an access notice. The rat duct experiment and its methods cannot be verified from the title.

Evidence for Na+ independent active secretion of K+ and HCO3- by rat salivary duct epithelium (Supplied page, access notice)

The decisive experiment must use old and young mice subjected to irradiation.

Different experimental conditions. All experiments used female C57BL/6 mice aged 6 to 7 weeks, with a single 10-Gy exposure where applicable. There was no old-versus-young comparison.

Long-term functional regeneration of radiation-damaged salivary glands through delivery of a neurogenic hydrogel (Materials and Methods, Animal studies; γ-Radiation of salivary glands)

Following irradiation, salivary glands receiving local cevimeline must be compared with glands receiving vehicle in the old and young mouse groups.

Different experimental conditions. Local cevimeline and cevimeline-alginate were compared with saline or alginate controls after irradiation, but only in one young-adult age group.

Long-term functional regeneration of radiation-damaged salivary glands through delivery of a neurogenic hydrogel (Results, Figs. 2-4; Materials and Methods, Periglandular application)

The treatment must be washed out before isolated ducts are tested.

Different experimental conditions. Saliva was collected four days after injection to avoid residual cevimeline stimulation. This is a timing control in intact animals, rather than treatment washout before isolated-duct testing.

Long-term functional regeneration of radiation-damaged salivary glands through delivery of a neurogenic hydrogel (Materials and Methods, Physiological saliva collection; Discussion)

The same model primary secretion must be delivered through isolated ducts at a fixed flow rate.

Not verified in the article. No supplied experimental account delivers identical model primary secretion through isolated ducts at a fixed flow rate.

CO₂, temperature, volume, and initial acidity must be controlled during the experiment.

Not verified in the article. Joint control of CO₂, temperature, volume and initial acidity during the proposed ductal buffering assay is not documented.

Bicarbonate must be added separately to the final sample as a control for the measured chemical limitation.

Not verified in the article. Neither available full study adds bicarbonate to the final sample as a rescue control for chemical buffering limitation.

At normal input flow, the damaged old duct is predicted to retain lower buffering capacity, which bicarbonate addition to the final sample will restore.

Not verified in the article. Persistent low buffering in damaged old ducts at normal input flow, followed by bicarbonate rescue, is not demonstrated.

The primary outcome at the fourth week must be the amount of acid neutralized per unit volume of output fluid to a specified pH.

Different experimental conditions. The mouse study measured stimulated saliva output by weight and assessed tissue recovery. It did not measure week-four acid neutralization per output volume to a specified pH.

Long-term functional regeneration of radiation-damaged salivary glands through delivery of a neurogenic hydrogel (Materials and Methods, Physiological saliva collection; Maximum saliva collection; Figs. 3-4)

Precise disappearance of the buffering difference at the specified flow rate would reject a separate ductal defect.

Not verified in the article. No study applies precise disappearance of a buffering difference at fixed flow as the criterion for rejecting a separate ductal defect.

An unirradiated control subjected to the same cannulation procedure is required because manual cannulation damages small ducts.

Not verified in the article. The mouse study includes unirradiated controls, but no matched duct-cannulation procedure. The required control for cannulation injury is therefore unverified.

Restoration by bicarbonate addition to the sample confirms a chemical deficit while leaving its molecular cause unidentified.

Not verified in the article. The supplied studies do not perform bicarbonate rescue that establishes a chemical deficit while leaving its molecular cause unresolved.

A positive result would justify adding ductal processing of secretion to the criteria for salivary gland recovery.

Not verified in the article. No supplied study uses the proposed positive result to add ductal processing to criteria for recovery after irradiation.

If the hypothesis is refuted, this approach must not advance to the next stage.

Not verified in the article. A decision rule stopping further development after refutation of this ductal-defect hypothesis is not documented.

The animal must be the independent experimental unit.

Matches this study. Mice provide the biological replicates for the animal experiments; multiple tissue sections and imaging regions are sampled within animals.

Long-term functional regeneration of radiation-damaged salivary glands through delivery of a neurogenic hydrogel (Fig. 1 legend; Materials and Methods, Periglandular application; Quantification of immunofluorescent images)

Experimental conditions must be allocated randomly.

Not verified in the article. Random allocation of experimental conditions is not explicitly reported in the supplied methods.

Group codes must be concealed during measurement.

Not verified in the article. Unique animal identifiers and researcher blinding during analysis are reported. Concealment of group codes during measurement itself is not explicitly established.

Long-term functional regeneration of radiation-damaged salivary glands through delivery of a neurogenic hydrogel (Materials and Methods, Animal studies)

Before the main experiment, an independent pilot must establish reproducibility, the working time point, and the minimum distinguishable and biologically meaningful effect.

Not verified in the article. Sample-size calculations are described, but no independent pilot establishes all three required properties: reproducibility, working time point and a distinguishable biologically meaningful effect.

The contrast and its confidence interval must be estimated at the level of independent experimental units.

Not verified in the article. Animal data are reported with means, standard deviations and significance tests. The required animal-level buffering contrast and its confidence interval are not reported.

Long-term functional regeneration of radiation-damaged salivary glands through delivery of a neurogenic hydrogel (Materials and Methods, Statistical analyses; Figs. 1-4)

The experiment is inconclusive between the explanations if the intervention fails to separate the groups or if the confidence interval permits substantial effects in both directions.

Not verified in the article. The specified inconclusive-result rule, based on failed group separation or intervals permitting substantial effects in both directions, is not documented.

The proposed human trial concerns elderly people with residual erosions despite controlled dermatitis.

Different experimental conditions. The glove study involved healthy adults for model training and children with moderate-to-severe atopic dermatitis for clinical testing, rather than elderly people with residual erosions despite controlled dermatitis.

A Sensorised Glove to Detect Scratching for Patients with Atopic Dermatitis (Methods 2.3 and 2.6; Results 3.4.)

Repeated mechanical injury from scratching is hypothesized to maintain residual erosions, so reducing tangential force per movement should reduce injury and new erosions even at a comparable scratching frequency.

Different experimental conditions. Tape stripping aggravated dermatitis and barrier damage in mice, and hydrogel treatment reduced damage during controlled stimulation. The study tested pharmacological treatment and simulated scratching, not reduced tangential force per natural scratch in elderly patients.

Hydrogel dressing integrating FAK inhibition and ROS scavenging for mechano-chemical treatment of atopic dermatitis (Results and discussion, FAK phosphorylation is increased in AD skins and enhanced by scratching; Figures 2 and 5-7; Methods, Animal experiment.)

The human trial must measure scratching behavior, contact force, and skin damage separately.

Not verified in the article. The glove measured finger and hand movements and was compared with video observations. Separate measurements of contact force and resulting skin damage were absent.

A Sensorised Glove to Detect Scratching for Patients with Atopic Dermatitis (Methods 2.1-2.6; Results 3.4; Table 1.)

Before the clinical comparison, select two acceptable finger coverings with measured differences in tangential force.

Different experimental conditions. A sensor-equipped biking glove was evaluated for scratch detection. Two acceptable finger coverings with experimentally established differences in tangential force were not compared.

A Sensorised Glove to Detect Scratching for Patients with Atopic Dermatitis (Methods 2.1 and 2.6.)

Temperature and humidity must be similar with the two finger coverings.

Not verified in the article. No supplied study established comparable temperature and humidity under two finger coverings differing in tangential force.

Randomize participants to the two finger coverings in parallel groups and compare them under stable therapy.

Different experimental conditions. Mice were randomized among hydrogel treatment groups during continued chemical induction and tape stripping. This differs from parallel randomization of patients to two finger coverings under stable therapy.

Hydrogel dressing integrating FAK inhibition and ROS scavenging for mechano-chemical treatment of atopic dermatitis (Methods, Animal experiment; Figure 6.)

Record movements during nocturnal scratching and obtain photographs of skin that is intact at baseline.

Different experimental conditions. Movement recording and video validation occurred during a short awake session. The study did not combine nocturnal recording with photographs tracking initially intact skin.

A Sensorised Glove to Detect Scratching for Patients with Atopic Dermatitis (Methods 2.6; Results 3.4; Discussion.)

The primary outcome is the frequency of new linear erosions per unit of a predefined, outlined area of initially intact skin over 14 nights.

Different experimental conditions. Outcomes included dermatitis scores, histology, inflammatory markers, and barrier proteins after 10 treatment days in mice. New linear erosions per predefined intact area over 14 nights were not measured.

Hydrogel dressing integrating FAK inhibition and ROS scavenging for mechano-chemical treatment of atopic dermatitis (Figures 6-7; Methods, Animal experiment.)

Use movement frequency to test the mechanism, and do not retrospectively select only participants with matching behavior.

Not verified in the article. No supplied study used movement frequency to test the covering mechanism with the specified prohibition on retrospective selection for matching behavior.

Fewer new erosions with the lower-force covering at a comparable movement frequency would support the proposed mechanism.

Not verified in the article. No supplied result shows fewer new erosions with a lower-force finger covering at comparable movement frequency.

Comparable movements with no substantial reduction in erosions at lower tangential force would refute the proposed mechanism.

Not verified in the article. No supplied study tested the specified null-result criterion under verified lower tangential force and comparable movements.

If skin damage decreases only alongside fewer movements or changed sleep, the result demonstrates the overall intervention effect but does not isolate the effect of force per movement.

Not verified in the article. The authors recognized that reduced scratching frequency can confound treatment assessment and controlled mechanical stimulation in mice. They did not test the specified human distinction between force, fewer movements, and changed sleep.

Hydrogel dressing integrating FAK inhibition and ROS scavenging for mechano-chemical treatment of atopic dermatitis (Discussion, controlled mechanical scratching; Methods, Animal experiment.)

The exploratory aging-related prediction is that, at an equal number of scratches, the benefit of reducing tangential force will be greater in participants with slower baseline skin barrier recovery.

Not verified in the article. No supplied study tested whether slower baseline barrier recovery predicts greater benefit from force reduction at equal scratch counts.

Measure baseline skin barrier recovery after clinically necessary dressing removal independently and before the observation period begins.

Not verified in the article. Independent baseline measurement of barrier recovery after clinically necessary dressing removal, before observation, was not documented in the supplied studies.

The experiment is proposed, and its results have not yet been obtained.

Not verified in the article. The submitted proposal states that results have not yet been obtained. This is its declared status, rather than a finding independently established by the supplied literature.

The proposed test uses hepatocytes from elderly donors as mature secretory cells.

Different experimental conditions. The hepatocyte experiments used the rat liver cell line BRL-3A; hepatocytes from elderly human donors were not studied.

Family with sequence similarity 134 member B-mediated reticulophagy ameliorates hepatocyte apoptosis induced by dithiothreitol (Materials and Methods: Cell culture and experiment protocol.)

FAM134B-dependent disposal of the endoplasmic reticulum clears aggregates, whereas a stronger disposal regimen reduces the reserve of functional endoplasmic reticulum.

Not verified in the article. The study establishes selective disposal of misfolded procollagen through the calnexin-FAM134B pathway. It does not establish the combined mechanism in which stronger disposal continues clearing aggregates while depleting functional reticulum reserve.

A selective ER-phagy exerts procollagen quality control via a Calnexin-FAM134B complex (Results: FAM134B is required for autophagy of procollagen; Figures 3, 4 and 7; Figure EV3.)

Excessively prolonged disposal of the endoplasmic reticulum is proposed to reduce the output of a mature secretory cell.

Not verified in the article. No supplied experiment links excessively prolonged reticulum disposal to reduced output of a mature secretory cell.

The stated experimental basis is the selective degradation of defective procollagen established in studies of FAM134B.

Matches this study. Misfolded procollagen was preferentially targeted for lysosomal degradation, FAM134B loss impaired delivery, and wild-type FAM134B restored delivery whereas its LC3-binding-defective variant did not.

A selective ER-phagy exerts procollagen quality control via a Calnexin-FAM134B complex (Results: FAM134B is required for autophagy of procollagen; Figures 3, 4 and 7; Figure EV3B-C.)

Recovery of secretion is predicted to peak at an intermediate intensity of FAM134B-dependent endoplasmic reticulum disposal, producing a nonlinear secretory response when the receptor is present in excess.

Not verified in the article. The supplied studies do not measure a secretory dose-response curve demonstrating an intermediate optimum or a decline in secretion at excess FAM134B.

All experimental groups undergo the same reversible stress before comparison.

Different experimental conditions. BRL-3A cells underwent dithiothreitol exposure for different durations, with knockdown comparisons during 24-hour treatment. This differs from comparing all groups after the same reversible stress and its release.

Family with sequence similarity 134 member B-mediated reticulophagy ameliorates hepatocyte apoptosis induced by dithiothreitol (Materials and Methods: Cell culture and experiment protocol; SiRNA transfections; Figures 1-5.)

The experiment compares four measured levels of FAM134B in hepatocytes.

Different experimental conditions. Three small interfering RNAs were screened to select an effective FAM134B knockdown reagent. These are not four measured FAM134B levels spanning the proposed hepatocyte response.

Family with sequence similarity 134 member B-mediated reticulophagy ameliorates hepatocyte apoptosis induced by dithiothreitol (Materials and Methods: SiRNA transfections; Figure 5A-D.)

The comparison includes an ATG8-defective variant at the highest FAM134B level.

Different experimental conditions. An LC3-binding-defective FAM134B variant was tested in knockout mouse embryonic fibroblasts. It was not the highest-level control in a four-level hepatocyte experiment.

A selective ER-phagy exerts procollagen quality control via a Calnexin-FAM134B complex (Results: FAM134B is required for autophagy of procollagen; Figure 4C.)

The experiment measures the dynamics of labeled membrane loss, the quantity of luminal aggregates, import, and early cell death.

Not verified in the article. Reticulum-lysosome colocalization and early/late apoptosis were assessed. The required combined measurements of labeled membrane-loss dynamics, luminal aggregates, import, and early death were not performed.

Family with sequence similarity 134 member B-mediated reticulophagy ameliorates hepatocyte apoptosis induced by dithiothreitol (Materials and Methods: Live imaging of ER and lysosome; Apoptosis assessment; Figures 2, 4 and 5.)

The primary outcome is secretion of newly synthesized albumin after 24 hours, including the secretion level without intervention.

Not verified in the article. Albumin is mentioned among proteins identified in hepatic microsomal proteomics. Secretion of newly synthesized albumin at 24 hours, including an untreated-intervention baseline, was not measured.

An N-terminal–truncated isoform of FAM134B (FAM134B-2) regulates starvation-induced hepatic selective ER-phagy (Results: FAM134B-2 regulates selective degradation of ER-retained secretary proteins but not bulk ER; Figure 6; Discussion.)

Monotonically increasing benefit across a range in which endoplasmic reticulum flux actually increases and cells remain alive would refute the proposed internal maximum within that range.

Not verified in the article. No supplied study tests monotonic secretory improvement across a verified increasing reticulum-flux range with preserved viability as a falsification criterion for an internal maximum.

The experiment uses old mice with labeled stroma to study excess fibroadipogenic stromal progenitor cells during muscle repair.

Different experimental conditions. The depletion study used three-month-old mice with rotator cuff injury or volumetric muscle loss. It does not establish the specified experiment in old mice with labeled stroma.

Phenotypic divergence in rotator cuff tear and volumetric muscle loss mouse models following fibroadipogenic progenitor depletion (Methods: FAP depletion mouse model; Surgical procedures.)

Tumor necrosis factor (TNF)-dependent removal of excess stromal progenitors participates in muscle repair.

Matches this study. The abstract explicitly reports macrophage TNF-induced progenitor apoptosis during acute muscle repair; the figure headings describe excess-cell clearance and increased collagen after TNF blockade. The supplied text is a subscription preview, so detailed methods remain unavailable.

Nilotinib reduces muscle fibrosis in chronic muscle injury by promoting TNF-mediated apoptosis of fibro/adipogenic progenitors (Abstract; figure headings 1, 3 and 4.)

Partial reduction of excess fibroadipogenic cells in old animals after myoblast fusion begins is predicted to reduce fibrosis while preserving muscle force.

Different experimental conditions. Partial depletion before injury reduced fibrosis and improved shoulder gait measures after rotator cuff injury; after volumetric muscle loss, gait measures showed no significant improvement. This differs from post-fusion depletion in old animals with demonstrated preservation of muscle force.

Phenotypic divergence in rotator cuff tear and volumetric muscle loss mouse models following fibroadipogenic progenitor depletion (Methods: FAP depletion mouse model; Results; Figures 3-6.)

The same reduction early in repair is predicted to deprive myoblasts of stromal support.

Different experimental conditions. Deleting Mst1/2 impaired progenitor support of myoblast proliferation and differentiation in coculture. This tests altered stromal function, rather than the proposed early removal of a cell number matched to late depletion.

MST1/2 regulates fibro/adipogenic progenitor fate decisions in skeletal muscle regeneration (Results: Inhibition of MST1/2 reduces IL-6 secretion by FAPs; Figure 5 and Figure S2.)

A titratable apoptosis mechanism is activated in the PDGFRα lineage to partially reduce the number of stromal progenitors.

Different experimental conditions. Tamoxifen-induced expression of diphtheria toxin A in the PDGFRα lineage produced partial depletion. A titrated apoptosis mechanism was not demonstrated; alternative induction protocols were discussed as future work.

Phenotypic divergence in rotator cuff tear and volumetric muscle loss mouse models following fibroadipogenic progenitor depletion (Methods: FAP depletion mouse model; Results: Tamoxifen induces reduction of FAP populations; Figure 2.)

The experimental groups receive apoptosis activation either before or after the appearance of the first new multinucleated muscle fibers.

Different experimental conditions. Depletion was induced during the two weeks before surgery. The study did not compare activation before versus after the appearance of the first new multinucleated fibers.

Phenotypic divergence in rotator cuff tear and volumetric muscle loss mouse models following fibroadipogenic progenitor depletion (Methods: FAP depletion mouse model; Figure 1.)

The number of cells removed must be matched between the early and late intervention groups.

Not verified in the article. No supplied study matched the number of cells removed between early and late intervention groups.

The interventions are compared with vehicle and an intact lineage.

Matches this study. The depletion experiment included corn-oil vehicle controls and Cre-negative diphtheria-toxin-A mice, providing a lineage-intact genetic control. These controls were used in a different injury and timing design.

Phenotypic divergence in rotator cuff tear and volumetric muscle loss mouse models following fibroadipogenic progenitor depletion (Methods: FAP depletion mouse model; Surgical procedures; Figure 1b-c.)

Early stromal support of myoblasts is assessed functionally using coculture.

Matches this study. Progenitors isolated on injury day 3 were cocultured with C2C12 myoblasts, with functional measurements of proliferation, differentiation and fusion. This matches the coculture-support component, but not its integration with the proposed aged-mouse depletion experiment.

MST1/2 regulates fibro/adipogenic progenitor fate decisions in skeletal muscle regeneration (Results: Inhibition of MST1/2 reduces IL-6 secretion by FAPs; Figure 5E-K; Experimental procedures: FAPs isolation and Cell culture.)

The primary outcome is specific muscle force on day 35.

Different experimental conditions. Function was assessed through gait six weeks after surgery. Gait at six weeks is a different endpoint from specific muscle force on day 35.

Phenotypic divergence in rotator cuff tear and volumetric muscle loss mouse models following fibroadipogenic progenitor depletion (Methods: Gait analysis; Figures 4 and 6.)

The secondary outcomes are fibrosis area and the size of new muscle fibers.

Matches this study. The study quantified fibrotic connective-tissue area and regenerated myofiber size. These measurements match the specified outcome types, although they were not secondary outcomes of the proposed timing experiment.

AMP-activated protein kinase inhibition in fibro-adipogenic progenitors impairs muscle regeneration and increases fibrosis (Methods: Muscle histological examination; Figures 1C and 2D-E.)

The timing prediction is rejected if equal cell removal in the early and late phases produces equal muscle force.

Not verified in the article. No supplied study evaluated the rejection criterion of equal muscle force after equal cell removal in early and late repair.

The timing prediction is also rejected if the late intervention reduces collagen at the expense of muscle force.

Not verified in the article. No supplied study jointly tested collagen reduction and muscle-force loss after the specified late intervention as a rejection criterion.

The experiment must use cells from different age groups to examine repair during cellular aging.

Different experimental conditions. The closest peptide-residue study used HeLa and U2OS cell lines with chemical damage and recovery experiments, rather than cells grouped by age to investigate cellular aging.

SPRTN-dependent DPC degradation precedes repair of damaged DNA: a proof of concept revealed by the STAR assay (Materials and Methods: Cell culture, treatments, and cell counting; Results, Figures 3-7.)

Accelerated removal of the protein portion of a DNA-protein crosslink during cellular aging may leave a peptide residue after proteolysis, creating a second repair barrier.

Different experimental conditions. SPRTN-dependent proteolysis produced DNA-bound peptide residues whose removal lagged behind full-size protein degradation. DNA breaks and delayed proliferation supported a remaining repair problem, but accelerated proteolysis during cellular aging was not tested.

SPRTN-dependent DPC degradation precedes repair of damaged DNA: a proof of concept revealed by the STAR assay (Results, Figures 3, 4, 6 and 7; Discussion.)

Increasing SPRTN activity is expected to be beneficial only when subsequent processing of the damaged DNA strand remains intact, because impaired processing limits the benefit of increased SPRTN activity.

Different experimental conditions. Single and combined depletion experiments supported coordinated SPRTN and TDP1 action in endogenous histone H3-crosslink repair. They did not test whether increasing SPRTN activity improves residue-free, sequence-restored repair only when downstream processing is intact; endogenous TOP1 crosslinks also showed a different pathway relationship.

Tyrosyl-DNA phosphodiesterase 1 (TDP1) and SPRTN protease repair histone 3 and topoisomerase 1 DNA–protein crosslinks in vivo (Results, sections 3.4-3.5, Figures 2-3; Discussion and Figure 7.)

The experiment must compare substrates bearing a full crosslinked protein with substrates bearing a pre-shortened peptide of the same type.

Matches this study. The study compared an intact M.HpaII-crosslinked plasmid with the corresponding substrate pretreated with proteinase K to leave a four-amino-acid peptide. This substrate control was performed in Xenopus egg extracts, outside the proposed aging-cell experiment.

Replication-Coupled DNA-Protein Crosslink Repair by SPRTN and the Proteasome in Xenopus Egg Extracts (Results: SPRTN-Mediated DPC Proteolysis Ensures Efficient TLS, Figures S4L-S4N; STAR Methods: Preparation of DNA constructs.)

The protein and peptide residues must be measured independently.

Matches this study. Separate gel fractions were analyzed by mass spectrometry to distinguish full-size proteins from degradation products, and electrophoresis and immunoblotting tracked protein and peptide species separately during recovery.

SPRTN-dependent DPC degradation precedes repair of damaged DNA: a proof of concept revealed by the STAR assay (Materials and Methods: Mass spectrometry; Results, Figures 3B-C, 4B-E and 6E.)

SPRTN must be compared with an inactive variant at the same replication phase.

Matches this study. Wild-type SPRTN and catalytically inactive E112Q were compared in HeLa cells subjected to the same double-thymidine synchronization and release into early/mid S phase. The measured outcome was crosslinked DNMT1 cleavage, without an aging comparison.

SPRTN patient variants cause global-genome DNA-protein crosslink repair defects (Results: SPRTN cleaves DNMT1-DPCs, Figure 3b; Figure 2a; Methods: siRNA transfection and Purification of x-linked proteins.)

The primary outcome must be the yield of molecules with a restored sequence and no covalent residue.

Different experimental conditions. The study quantified supercoiled replication products and nascent-strand extension across the lesion. These readouts establish replication completion or lesion bypass, not the yield of molecules jointly verified to have restored sequence and no covalent peptide residue.

Replication-Coupled DNA-Protein Crosslink Repair by SPRTN and the Proteasome in Xenopus Egg Extracts (Results, Figures 3B-F and 4F-G; STAR Methods: Xenopus Egg Extracts and DNA Replication.)

Disappearance of the large protein must be recorded separately from the final yield of repaired molecules.

Different experimental conditions. Crosslinked-protein degradation was measured separately from DNA replication products. However, the DNA endpoint was a replication/bypass product rather than the specified fully repaired, residue-free molecule.

Replication-Coupled DNA-Protein Crosslink Repair by SPRTN and the Proteasome in Xenopus Egg Extracts (Results, Figure 3B-C and 3E-F; Figure 4B and 4F-G.)

If SPRTN improves the final yield equally at any rate of peptide processing, the proposed second repair limitation is not detected; this is the stated falsification criterion.

Not verified in the article. No supplied study varied peptide-processing rates while testing whether increased SPRTN activity produced an equal improvement in the specified final repair yield.

Identical wiping is hypothesized to disrupt the skin barrier more strongly during the wet phase than during the dry phase.

Not verified in the article. The article analyzes friction and contact mechanics during wetting and drying, but does not measure barrier disruption from identical wet-phase and dry-phase wiping.

Surface topography and contact mechanics of dry and wet human skin (Results and Discussion: Contact mechanics of dry and wet skin; Figure 7; Conclusion.)

Aged skin may sustain damage predominantly when hydration coincides with tangential force.

Not verified in the article. The supplied studies do not establish preferential damage to aged skin when hydration coincides with tangential force.

Increased surface friction is predicted to explain part of the damage associated with wet wiping.

Not verified in the article. The available abstract reports higher friction coefficients in wet ex vivo skin, but does not establish that this friction causes part of the barrier damage from wet wiping.

On the role of adhesive forces in the tribo-mechanical performance of ex vivo human skin (Abstract; Introduction.)

Changes in the stratum corneum itself may cause additional vulnerability during wet wiping that persists when mechanical work is equalized.

Not verified in the article. Water-dependent physicochemical changes in the stratum corneum are proposed to influence friction. Additional tissue damage persisting at equal mechanical work is not tested.

On the role of adhesive forces in the tribo-mechanical performance of ex vivo human skin (Abstract.)

The experiment uses paired skin explants from older and young donors.

Different experimental conditions. The study uses three abdominal skin samples from one donor, rather than paired explants from older and young donor groups.

On the role of adhesive forces in the tribo-mechanical performance of ex vivo human skin (Introduction, final paragraph; Ex vivo human skin samples.)

Paired explants are randomly assigned to wiping during either the wet phase or the dry phase.

Not verified in the article. Random allocation of paired explants to wet-phase or dry-phase wiping is not documented in the supplied material.

In the main comparison between wet-phase and dry-phase wiping, the integral of tangential force over the movement path is equalized using a sensor.

Not verified in the article. No supplied experiment equalizes the sensor-measured integral of tangential force over the movement path between wiping phases.

An additional comparison between wet-phase and dry-phase wiping uses equal normal force and an equal number of movements.

Not verified in the article. The article reproduces glass-ball sliding measurements at a normal load of 0.5 N during wetting and drying. It does not document the additional wiping comparison with both equal normal force and equal movement counts.

Surface topography and contact mechanics of dry and wet human skin (Figure 7; Results and Discussion: Capillary adhesion.)

Total moisture exposure is equalized across the experimental groups.

Not verified in the article. Equal total moisture exposure across wet-phase and dry-phase wiping groups is not documented.

The experiment includes groups without wiping.

Not verified in the article. No supplied study documents non-wiped control groups for the proposed barrier-damage comparison.

The primary outcome is skin permeability measured one day after a common drying phase.

Not verified in the article. Permeability measured one day after a common drying phase is not reported as an outcome in the supplied studies.

The number of removed corneocytes and tissue viability are measured independently.

Not verified in the article. Independent measurements of removed corneocyte numbers and tissue viability are not documented.

An effect of wet-phase wiping that occurs only under equal normal force and disappears under equal tangential work would support the surface-friction explanation and refute additional vulnerability of wet tissue at equal work.

Not verified in the article. No supplied study compares barrier damage under equal normal force and equal tangential work to distinguish surface friction from additional wet-tissue vulnerability.

Age specificity is tested through a direct statistical interaction between donor age group and the wet-phase versus dry-phase wiping condition.

Not verified in the article. A direct statistical interaction between donor age group and wet-phase versus dry-phase wiping is not reported.

The hypothesis concerns aging dividing cells.

Different experimental conditions. The cell-cycle modulation study used 293T and BHK-21 cells, pig fetal fibroblasts and pig embryos, rather than an experimentally characterized population of aging dividing cells.

Modulation of cell cycle increases CRISPR-mediated homology-directed DNA repair (Materials and methods: Cell lines; Embryo injection.)

The intervention is a small, reversible extension of G2 that delays entry into mitosis.

Different experimental conditions. The study induced S and/or G2/M accumulation using docetaxel, irinotecan, nocodazole or mitomycin C, with 48-hour treatment in the editing assays. This differs from a small, reversible extension specifically of G2 before mitotic entry.

Modulation of cell cycle increases CRISPR-mediated homology-directed DNA repair (Results: Effects of cell cycle inhibitor on CRISPR/Cas9-mediated KI; Figures 1-2; Materials and methods: KI efficiency assay.)

G2 extension may improve accurate homologous repair of breaks only while RAD51 loading remains functional and the repair template remains available and used; it may be ineffective when the template is barely used.

Not verified in the article. RAD51 depletion impaired homologous repair synthesis and left persistent single-stranded intermediates in G2. This supports a mechanistic component, but the study did not test whether the benefit of extending G2 depends on functional RAD51 loading and continued template use.

ATM and Artemis promote homologous recombination of radiation-induced DNA double-strand breaks in G2 (Results: Artemis- and ATM-deficient cells show a defect in IR-induced repair synthesis during HR in G2; RPA, Rad51 and ssDNA foci formation is compromised; Figures 3 and 5.)

The experiment must introduce the same break in G2 across the compared groups.

Different experimental conditions. The same inducible I-Sce I reporter break was examined at several cell-cycle stages, including G2. However, the maintained-arrest versus release comparison concerned mitotic cells, rather than groups receiving the same break in G2.

Mitotic cells can repair DNA double-strand breaks via a homology-directed pathway (Materials and methods: Establishment of the SCneo-Mer-I-Sce I cell line; Results: Cell cycle effect on HDR; Figures 2-4.)

Reversible G2 extension must be compared with a control under both intact and partially reduced RAD51 loading.

Not verified in the article. The study compared control cells with cells depleted of RAD51 or BRCA2, but did not cross intact versus partially reduced RAD51 loading with reversible G2 extension versus its control.

ATM and Artemis promote homologous recombination of radiation-induced DNA double-strand breaks in G2 (Results and figure legends: Figures 2C, 3 and 5.)

The compared groups must have equal numbers of divisions during subsequent observation.

Not verified in the article. None of the supplied studies equalized subsequent division counts between the proposed G2-extension and control groups.

Cell-cycle restart must be checked after release of the G2 delay.

Different experimental conditions. The study followed spontaneous recovery from irradiation-induced arrest, checkpoint override and subsequent proliferation. These measurements differ from checking restart after release of an experimentally imposed, small G2 extension.

Persistent repair intermediates induce senescence (Results: Spontaneous recovery awaits successful repair; ATR signalling is the main driver of cell cycle exit in G2 phase; Figures 1-2 and Supplementary Figure 2k,l.)

The expected repair benefit is an increased fraction of accurate products carrying template markers among the initially cut alleles.

Different experimental conditions. The study measured donor-derived insertions using fluorescence, HindIII digestion and protein tags. Its HindIII/T7E1 ratio estimates insertion relative to detected editing events; it does not measure the specified fraction of accurate template-marked products among independently established initially cut alleles.

Modulation of cell cycle increases CRISPR-mediated homology-directed DNA repair (Results: Production of KI cells and embryos by cell cycle synchronization; Figure 3; Materials and methods: Screening of ssODN-mediated KI cells.)

The expected benefit must be accompanied by normal segregation at the next mitosis.

Not verified in the article. The supplied studies do not establish normal chromosome segregation at the next mitosis as an outcome accompanying improved repair after the proposed G2 extension. Mitotic entry, metaphase repair measurements and embryo development do not establish this endpoint.

A reduction in damage attributable solely to the absence of mitoses would mean that the intervention does not achieve its goal.

Not verified in the article. No supplied experiment applies the specified failure criterion by distinguishing genuine repair improvement from damage reduction attributable solely to avoided mitoses under matched subsequent division counts.

Failure to increase accurate repair at equal RAD51 loading would mean that the intervention does not achieve its goal.

Not verified in the article. The study measured RAD51 expression and inferred possible RAD51 independence from its decrease. It did not hold RAD51 loading equal while comparing accurate repair with and without G2 extension, so the specified failure criterion was not tested.

Modulation of cell cycle increases CRISPR-mediated homology-directed DNA repair (Results: Cell cycle synchronization promotes activation of HDR factors; Figures 4E and 5.)

The experiment investigates renal tubular aging using proximal tubule chips from young adult and elderly donors.

Different experimental conditions. The experiments use HEK-293/HEK-293T cells and mouse fibroblasts, rather than donor-age-stratified proximal tubule chips.

p97-dependent retrotranslocation and proteolytic processing govern formation of active Nrf1 upon proteasome inhibition (Materials and methods: Cell culture; Figures 1-4.)

NFE2L1 triggers compensatory proteasome formation after proteasome inhibition.

Matches this study. Wild-type Nrf1/NFE2L1 restores proteasome-subunit gene induction after MG132 treatment in Nrf1-deficient fibroblasts, whereas a cleavage-defective mutant is impaired, supporting the compensatory proteasome-production pathway.

p97-dependent retrotranslocation and proteolytic processing govern formation of active Nrf1 upon proteasome inhibition (Results: Transcriptionally active Nrf1 p110 is derived from p120 by proteolytic processing; Figure 2A-B.)

The proposed mechanism is that the rate of proteasome activity recovery between episodes of overload determines the functional reserve of aged renal epithelium.

Not verified in the article. The supplied studies do not establish that recovery kinetics between overload episodes determine the functional reserve of aged renal epithelium.

Proximal tubule chips receive two reversible pulses of partial proteasome inhibition that constitute the two proteotoxic challenges.

Different experimental conditions. Cells receive one 1-hour pulse of bortezomib or carfilzomib followed by drug removal. This differs from two reversible partial-inhibition pulses in proximal tubule chips; carfilzomib itself is irreversible.

Early recovery of proteasome activity in cells pulse-treated with proteasome inhibitors is independent of DDI2 (Results; Figure 1B-C; Materials and methods: Cell culture; Discussion.)

The experimental intervention briefly activates the active form of NFE2L1 during the interval between the two proteotoxic pulses.

Not verified in the article. No supplied experiment briefly activates active NFE2L1 specifically during an interval between two proteotoxic pulses.

Brief activation of the active form of NFE2L1 between pulses is predicted to benefit the aged tubule only if degradation of a protein substrate has recovered by the start of the second challenge.

Not verified in the article. The requirement that aged-tubule protection depends on restored protein-substrate degradation before a second challenge is untested in the supplied studies.

Activation of NFE2L1 between challenges is compared with activation only after the second challenge, an inactive variant, and no intervention.

Different experimental conditions. Wild-type Nrf1, a cleavage-defective mutant, and vector controls are compared during MG132 treatment. The required comparison of between-pulse activation with activation only after the second challenge is absent.

p97-dependent retrotranslocation and proteolytic processing govern formation of active Nrf1 upon proteasome inhibition (Figure 2A-B.)

The duration of the interval between the two challenges is varied.

Different experimental conditions. Recovery is sampled at different times after a single pulse; the interval between two challenges is not varied.

Early recovery of proteasome activity in cells pulse-treated with proteasome inhibitors is independent of DDI2 (Figures 2A-B and 3A; Discussion.)

The first challenge is kept the same across donor age groups when comparing proteasome recovery time and the functional benefit of NFE2L1.

Not verified in the article. No supplied study compares donor age groups under an identical first challenge to assess recovery time and NFE2L1-mediated functional benefit.

The comparison between donor age groups controls for the area of living epithelium.

Not verified in the article. Control for living epithelial area in a donor-age comparison is not documented. Cell-viability normalization in the pulse-treatment study does not establish this control.

Proteasome activity is measured using a protein reporter and independently using native complexes.

Different experimental conditions. Activity is measured by cleavage of short peptide substrates using Proteasome-Glo or Suc-LLVY-AMC. These assays do not provide the specified protein-degradation reporter plus independent native-complex measurements.

Early recovery of proteasome activity in cells pulse-treated with proteasome inhibitors is independent of DDI2 (Materials and methods: Proteasome activity assays; Figures 1-3.)

The primary outcome is recovery of receptor-dependent albumin uptake per unit of initial surface area at 48 hours after the second challenge.

Not verified in the article. Receptor-dependent albumin-uptake recovery per initial surface area at 48 hours after a second challenge is not measured in the supplied studies.

Protection of transport despite confirmed absence of proteasome recovery would refute the proposed mechanism.

Not verified in the article. No supplied experiment tests whether renal transport remains protected despite confirmed failure of proteasome recovery.

The experiment uses hepatocytes from old and young mice.

Different experimental conditions. The combined PEX16 and NBR1 experiment used human retinal pigment epithelial cells. Additional experiments used mouse embryonic fibroblasts, rather than hepatocytes from old and young mice.

Knockdown of PEX16 Induces Autophagic Degradation of Peroxisomes (Materials and Methods 4.2; Results 2.1-2.3)

In old hepatocytes, enhanced removal of oxidized peroxisomes through the peroxisome receptor NBR1 is hypothesized to restore shortening of very long-chain fatty acids only if formation of new functional peroxisomes is preserved.

Not verified in the article. PEX1-depleted HeLa cells provide evidence connecting oxidative stress, NBR1 recruitment and pexophagy. The study does not establish restoration of fatty-acid shortening in aged hepatocytes or its dependence on new functional peroxisomes.

Regulation of pexophagy by a novel TBK1-MARCHF7-PXMP4-NBR1 axis in PEX1-depleted HeLa cells (Results, Figures 5-6; Discussion)

Reducing the oxidative signal alone is hypothesized to be insufficient to restore fatty-acid shortening.

Not verified in the article. N-acetylcysteine and peroxisome-targeted catalase were used to examine oxidative signaling. These experiments measured oxidative signals, autophagy and peroxisome abundance, but did not determine whether antioxidant treatment alone restores fatty-acid shortening.

PEX13 prevents pexophagy by regulating ubiquitinated PEX5 and peroxisomal ROS (Results, Figures 6-7)

The number of peroxisomes that must replace those removed to restore metabolism remains unspecified.

Not verified in the article. The hypothesis specifies no numerical replacement threshold. The supplied studies do not determine how many newly formed peroxisomes must replace removed organelles to restore metabolism in the proposed system.

Photolabeling is used to distinguish old peroxisomes from newly appearing peroxisomes.

Not verified in the article. No supplied primary study uses photolabeling to distinguish existing from newly appearing peroxisomes. Fluorescent import markers and pH-sensitive pexophagy reporters do not provide this organelle-age comparison.

NBR1 is altered in combination with partial restriction of peroxisome biogenesis through inducible reduction of PEX16.

Different experimental conditions. NBR1 and PEX16 were jointly depleted using small interfering RNAs, so their combined manipulation is already reported. However, this was not an inducible, calibrated partial restriction of replacement paired with enhanced pexophagy; NBR1 depletion did not rescue peroxisome abundance.

Knockdown of PEX16 Induces Autophagic Degradation of Peroxisomes (Results 2.3, Figure 3A-B; Materials and Methods 4.3)

Enzyme import into the remaining peroxisomes is verified, and altered import into old peroxisomes makes the experiment ambiguous.

Not verified in the article. The study reports unchanged catalase localization after PEX16 depletion, providing a relevant partial control. It does not verify enzyme import specifically into photolabeled old peroxisomes during the proposed combined intervention or apply the specified ambiguity criterion.

PEX13 prevents pexophagy by regulating ubiquitinated PEX5 and peroxisomal ROS (Results, “Peroxisomal localized CAT prevents PEX1 and PEX13 depletion induced ROS”; Figure S5C-D)

After stress, fatty-acid shortening is assessed by measuring conversion of labeled C26:0 into shortened products.

Different experimental conditions. Radioactively labeled C26:0 was used to measure beta-oxidation in PEX1-mutant fibroblasts after compound treatment. This is a close functional assay, but the specified post-stress measurement of shortened products in the NBR1/PEX16 hepatocyte experiment was not performed.

Autophagy Inhibitors Do Not Restore Peroxisomal Functions in Cells With the Most Common Peroxisome Biogenesis Defect (Results, Figures 3A and 4G; Materials and Methods, “Biochemical Assays”)

The number of living cells is controlled when measuring conversion of labeled C26:0.

Not verified in the article. Cell viability and cell concentration were assessed, and lipid analysis used a fixed protein amount. These procedures do not establish control of living-cell number during a labeled-C26:0 conversion assay.

The peroxisomal AAA ATPase complex prevents pexophagy and development of peroxisome biogenesis disorders (Results, Figure 6A; Materials and Methods, “MTT assay” and “LC-MS/MS analysis”)

The decisive comparison tests whether enhanced pexophagy improves fatty-acid shortening differently under conditions of sufficient versus limited peroxisome replacement; equal improvement in these conditions would reject the proposed dependence on replacement.

Not verified in the article. No supplied study compares the improvement in fatty-acid shortening caused by enhanced pexophagy under sufficient versus limited peroxisome replacement, with equal improvement serving as the falsification criterion.

Delivery of a cholinergic signal to acini is proposed to improve repair only when the polarity of newly formed cells is preserved.

Not verified in the article. Denervation, lineage tracing and muscarinic stimulation establish cholinergic regulation of acinar replenishment, but preservation of new-cell polarity was not tested as a necessary condition.

Salivary glands regenerate after radiation injury through SOX2-mediated secretory cell replacement (Results, Figures 3-6)

Regenerated acini from aged tissue may release secretion into the intercellular space despite a normal response to an agonist, because their orientation and polarity determine whether secretion reaches the duct lumen or the intercellular space.

Different experimental conditions. Genetically modified mouse glands showed disrupted polarity and reduced secretion with preserved intracellular calcium release but impaired calcium influx. Aged regenerated acini and secretion into intercellular spaces were not examined.

Specific 3-O-sulfated heparan sulfate domains regulate salivary gland basement membrane metabolism and epithelial differentiation (Results, Figure 4c-g; Discussion)

The alternative explanation attributes poor secretory output exclusively to reduced synthesis of secretion.

Not verified in the article. No supplied study directly compares secretion redirection with an explanation based exclusively on reduced synthesis in the proposed system.

The supporting biological evidence describes SOX2-positive cells replenishing the acinar lineage in the mouse sublingual gland after irradiation, with replenishment dependent on a neural signal that could be reproduced with a muscarinic agonist.

Matches this study. Mouse sublingual lineage tracing demonstrated post-irradiation replenishment by SOX2-positive cells; denervation and muscarinic agonist/antagonist experiments established neural and muscarinic regulation.

Salivary glands regenerate after radiation injury through SOX2-mediated secretory cell replacement (Results, Figures 3, 5 and 6; Materials and Methods, Organ culture experiments)

The supporting evidence describes prolonged local delivery of cevimeline in a gel to irradiated salivary glands of adult mice as supporting acinar regeneration and recovery of secretion compared with an injury control.

Matches this study. Local cevimeline-alginate delivery supported acinar replenishment and secretory recovery in irradiated adult mice. A single dose gave transient functional benefit; long-term preservation required subsequent weekly cevimeline injections.

Long-term functional regeneration of radiation-damaged salivary glands through delivery of a neurogenic hydrogel (Results, Figures 2-4; Materials and Methods, Periglandular application)

The supporting evidence also describes improved recovery with a gel containing laminin peptides in irradiated mouse submandibular glands compared with a control.

Matches this study. Fibrin hydrogels conjugated to laminin-1 peptides A99 and YIGSR improved epithelial organization, polarity and stimulated saliva output in irradiated mouse submandibular glands versus untreated irradiated controls.

Laminin-1 Peptides Conjugated to Fibrin Hydrogels Promote Salivary Gland Regeneration in Irradiated Mouse Submandibular Glands (Materials and Methods, Transdermal Injection; Results, Figures 2, 3 and 5)

The decisive experiment must use polarized acini constructed from elderly donor cells in chips connected to a duct.

Different experimental conditions. Human parotid stem/progenitor cells from donors aged 22, 57 and 63 formed microstructures in hyaluronate hydrogels. These were not elderly-donor polarized acini in duct-connected chips.

Dynamic Assembly of Human Salivary Stem/Progenitor Microstructures Requires Coordinated α1β1 Integrin-Mediated Motility (Materials and Methods, Tissue Culture and Encapsulation and Hydrogel Culture)

After injury, restoration of basal orientation on laminin must be compared with a control coating at an equal agonist dose.

Different experimental conditions. The study compared injected laminin-peptide fibrin hydrogel with untreated irradiated glands and used pilocarpine plus isoproterenol for secretion testing. It did not compare laminin and control coatings for basal reorientation in chips.

Laminin-1 Peptides Conjugated to Fibrin Hydrogels Promote Salivary Gland Regeneration in Irradiated Mouse Submandibular Glands (Materials and Methods, Animals and Saliva Flow Rate Measurements; Figures 3 and 5)

Young donors must serve as a reference for the experiment.

Different experimental conditions. Young control mice were compared with naturally aged and D-galactose-treated mice. Young human donors were not a reference group for the proposed chip experiment.

Cellular Senescence Contributes to the Dysfunction of Tight Junctions in Submandibular Glands of Aging Mice (Materials and Methods, 2.1 Animals; Results, Figure 1)

Apical and external secretory output must be measured independently.

Not verified in the article. Independent measurement of apical and external secretory output in the proposed acinar system is absent from the supplied studies.

The experiment must confirm the calcium response, the total secretion level, and sealing integrity.

Not verified in the article. Calcium responses, whole-saliva flow and salivary proteins were assessed, but the combined verification of calcium response, total secretion and chip sealing integrity was not performed.

Specific 3-O-sulfated heparan sulfate domains regulate salivary gland basement membrane metabolism and epithelial differentiation (Results, Figure 4; Methods, Saliva collection and calcium measurements)

The primary outcome must be the fraction of stimulated secretion that reaches the duct lumen in a test on day ten.

Different experimental conditions. The measured outcome was whole-saliva flow on days 8 and 30, rather than the duct-luminal fraction of stimulated secretion on day ten.

Laminin-1 Peptides Conjugated to Fibrin Hydrogels Promote Salivary Gland Regeneration in Irradiated Mouse Submandibular Glands (Results, Figure 5; Materials and Methods, Saliva Flow Rate Measurements)

The epithelial donor must be the independent experimental unit.

Different experimental conditions. The human microstructure study defined sample size by events and pooled data across three donors. It did not use the epithelial donor as the independent unit of the proposed analysis.

Dynamic Assembly of Human Salivary Stem/Progenitor Microstructures Requires Coordinated α1β1 Integrin-Mediated Motility (Materials and Methods, Statistical Analysis)

Correction of orientation is predicted to increase the fraction of secretion reaching the duct lumen while total secretion remains similar.

Not verified in the article. Preserved polarity and improved saliva flow were reported together, but an increased luminal fraction at similar total secretion was not demonstrated.

Laminin-1 Peptides Conjugated to Fibrin Hydrogels Promote Salivary Gland Regeneration in Irradiated Mouse Submandibular Glands (Results, Figures 3 and 5)

The secretion redirection hypothesis is not supported if only total synthesis increases or if sealing the chip eliminates the differences.

Not verified in the article. No supplied experiment applies the specified synthesis-only or chip-sealing falsification tests.

The model supports conclusions about the direction of secretion.

Not verified in the article. No supplied study validates the proposed model for drawing conclusions about the direction of stimulated salivary secretion.

Basal leakage through the damaged chip must remain below the limit of the pilot test.

Not verified in the article. A pilot-defined upper limit for basal leakage through an injured chip is not reported.

A positive result would justify assessing the polarity of new acini before further stimulation; if the hypothesis is refuted, this approach must not proceed to the next stage.

Not verified in the article. The specified decision to assess polarity before further stimulation, or stop advancement after refutation, was not implemented in a supplied study.

Experimental conditions must be allocated randomly, and group codes must be concealed during measurement.

Matches this study. Wild-type animals were randomized and unique identifiers blinded researchers during analysis. This matches the methodological safeguard in animal experiments, not execution of the proposed chip experiment.

Salivary glands regenerate after radiation injury through SOX2-mediated secretory cell replacement (Materials and Methods, Animal experiments)

Before the main experiment, an independent pilot must establish reproducibility, the working time point, and the minimum distinguishable and biologically meaningful effect.

Not verified in the article. No independent pilot jointly establishes reproducibility, the working time point and the minimum distinguishable and biologically meaningful effect for the proposed experiment.

The contrast and its confidence interval must be estimated at the level of independent experimental units.

Not verified in the article. A donor-level contrast with its confidence interval for the proposed luminal-fraction outcome is not reported.

The experiment cannot distinguish the explanations if the intervention fails to separate the groups or if the confidence interval permits substantial effects in both directions.

Not verified in the article. The specified inconclusive-result rule based on intervention separation and confidence intervals allowing substantial effects in either direction is not reported.

The chemistry of the abasic residue is proposed to predict the need for long-patch repair of mitochondrial DNA.

Not verified in the article. The discussion identifies abasic sites arising from 1′-oxidation of deoxyribose as lesions requiring long-patch repair, but the study itself does not experimentally compare abasic-residue chemistries.

Maintenance of Flap Endonucleases for Long-Patch Base Excision DNA Repair in Mouse Muscle and Neuronal Cells Differentiated In Vitro (Introduction; Discussion, final paragraph.)

During cellular aging, limited mitochondrial FEN1-dependent repair capacity may selectively constrain removal of an oxidized residue that leaves a difficult-to-remove 5′ end, while processing of a simple substrate remains normal; this limitation should depend on lesion type.

Different experimental conditions. The study examines differentiation of mouse neuronal and muscle cells rather than cellular aging. Mitochondrial FEN1 was maintained in neuronal cells, and flap-cleavage products implicated MGME1; selective FEN1 limitation for an oxidized residue was not tested.

Maintenance of Flap Endonucleases for Long-Patch Base Excision DNA Repair in Mouse Muscle and Neuronal Cells Differentiated In Vitro (Results 2.1-2.2; Discussion; Figures 2, 4 and 5.)

Simple and resistant 5′ residues must be tested in paired mitochondrial extracts.

Different experimental conditions. Mitochondrial extracts from proliferating and differentiated neuronal cells were compared using a flap substrate. This substitutes a preformed flap for the required paired comparison of simple and resistant 5′ residues.

Maintenance of Flap Endonucleases for Long-Patch Base Excision DNA Repair in Mouse Muscle and Neuronal Cells Differentiated In Vitro (Materials and Methods 4.7-4.8; Figure 4.)

Labels must be used to distinguish the length of the replaced DNA segment.

Different experimental conditions. Radiolabeled nucleotide incorporation detects newly synthesized intermediates and ligated circular products. It does not distinguish replacement-tract lengths during repair of the two specified residues.

Mitochondrial exonuclease EXOG supports DNA integrity by the removal of single-stranded DNA flaps (Materials and methods, Ligation assay—circular substrates; Figure 5.)

For each substrate, baseline repair activity must be compared with activity following addition of FEN1 and with an inactive control.

Not verified in the article. Purified FEN1 serves as a separate cleavage control. The required baseline, FEN1-addition and inactive-control comparison within mitochondrial extracts for each residue is absent.

Maintenance of Flap Endonucleases for Long-Patch Base Excision DNA Repair in Mouse Muscle and Neuronal Cells Differentiated In Vitro (Materials and Methods 4.8; Figures 3 and 4.)

The purity of the organelle preparations must be checked.

Matches this study. Mitochondrial preparations underwent gradient purification and proteinase K treatment; immunoblotting included mitochondrial Complex I and a nuclear marker to assess the fractions.

Maintenance of Flap Endonucleases for Long-Patch Base Excision DNA Repair in Mouse Muscle and Neuronal Cells Differentiated In Vitro (Materials and Methods 4.4; Figure 2 and its caption.)

The primary outcome must be the fraction of ligated molecules retaining the original sequence, measured separately for each residue.

Different experimental conditions. The study measures ligation of substrates carrying short or long flaps and identifies closed circular products. It does not measure the fraction retaining the original sequence separately for simple and resistant abasic residues.

Mitochondrial exonuclease EXOG supports DNA integrity by the removal of single-stranded DNA flaps (Results, DNA flaps removal by EXOG provides substrates for ligation; Figure 5; Supplementary Figure S12 as described in the main text.)

Addition of FEN1 is predicted to increase final-molecule yield preferentially for the resistant substrate.

Different experimental conditions. A purified system demonstrates that mitochondrial exo/endonuclease G (EXOG) supports ligated-product formation from flap substrates. The enzyme, substrate comparison and system differ from preferential rescue of a resistant residue by FEN1 in mitochondrial extracts.

Mitochondrial exonuclease EXOG supports DNA integrity by the removal of single-stranded DNA flaps (Results, DNA flaps removal by EXOG provides substrates for ligation; Figure 5.)

A FEN1-induced change in intermediates without an increase in final-molecule yield must count as a refutation of the proposed specific limitation.

Not verified in the article. No supplied study tests whether FEN1 changes intermediates without increasing final-product yield as a refutation of the proposed lesion-specific limitation.

Identical responses of the simple and resistant substrates to FEN1 must count as a refutation of the proposed specific limitation.

Not verified in the article. No supplied study compares FEN1 responses of the specified simple and resistant residues and treats identical responses as a refutation of the proposed specific limitation.

The hypothesis concerns aging intestinal stem cells and is to be tested in organoids from young and older donors.

Different experimental conditions. The study examines intestinal stem cells across mouse ages and organoids from conditional Setd2-knockout and control mice. It does not perform the proposed comparison in organoids from young and older donors.

Histone 3 lysine 36 trimethylation by SETD2 shapes an epigenetic landscape in intestinal stem cells to orchestrate lipid metabolism and attenuate cell senescence (Results, Figures 1-2; Materials and methods, In vivo tamoxifen treatment and organoid culture.)

H3K36me3 recruits MSH6, and an age-associated reduction in this mark may weaken MSH6 recruitment and increase copying errors in particular genomic regions.

Not verified in the article. Age-associated H3K36me3 loss in mouse intestinal stem cells is demonstrated. The causal sequence connecting this loss to reduced MSH6 recruitment and regional copying errors is not tested.

Histone 3 lysine 36 trimethylation by SETD2 shapes an epigenetic landscape in intestinal stem cells to orchestrate lipid metabolism and attenuate cell senescence (Results, The levels of H3K36me3 are reduced in the intestinal stem cells of aged mice; Figure 1.)

Restoring H3K36me3 is proposed to promote repair of copying errors and reduce new errors only when the mark-binding region of MSH6 is intact.

Different experimental conditions. Active SETD2 restores H3K36me3 and partially rescues homologous recombination in U2OS cells. The study investigates double-strand-break repair involving LEDGF, CtIP, RPA and RAD51, rather than MSH6-binding-dependent correction of copying errors.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results, H3K36me3 Is Required for Homologous Recombination Repair; Figures 4-5.)

SETD2 restoration must be compared with a catalytic control in both an ordinary MSH6 background and a background containing an MSH6 variant unable to bind H3K36me3.

Not verified in the article. Wild-type and methyltransferase-dead SETD2 are compared after endogenous SETD2 depletion. This catalytic control is present, but the comparison is not crossed with ordinary and H3K36me3-binding-defective MSH6.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results, H3K36me3 Is Required for Homologous Recombination Repair; Figure 4A-D and Figure S4A-C.)

The experimental comparisons must match expression, cell divisions, baseline H3K36me3 levels and copy number.

Not verified in the article. Neither supplied study verifies matching expression, cell divisions, baseline H3K36me3 and copy number across the proposed SETD2-by-MSH6 experimental groups.

The primary outcome is copying errors per division in genomic regions with restored H3K36me3, measured using both clonal sequencing and duplex sequencing.

Different experimental conditions. The study measures mutation frequency after an induced break at HPRT and sequences the break junction in isolated clones. It does not combine clonal and duplex sequencing to measure copying errors per division across regions with restored H3K36me3.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results, SETD2 Suppresses Break-Induced Mutations; Figure 1; Experimental Procedures, I-SceI-Inducible HPRT Mutation Assay.)

MSH6 occupancy must be measured independently.

Not verified in the article. Neither supplied study independently measures MSH6 occupancy. Measurements of other repair proteins in the homologous recombination study do not satisfy this requirement.

Errors per division are predicted to decrease in regions with restored H3K36me3 only when MSH6 retains its ability to bind the mark.

Not verified in the article. No supplied experiment demonstrates a regional reduction in copying errors per division after H3K36me3 restoration that depends on intact MSH6 binding.

A decrease in errors in the presence of the MSH6 variant unable to bind the mark rejects the proposed mechanism.

Not verified in the article. The proposed falsification test measuring error reduction after restoration in an MSH6 nonbinding-variant background is absent from the supplied studies.

A decrease in errors that does not correspond to the genomic map of H3K36me3 restoration rejects the proposed mechanism.

Not verified in the article. The supplied studies do not test whether the genomic distribution of error reduction corresponds to the H3K36me3 restoration map or use discordance to reject the mechanism.

The hypothesis proposes that age-related risk depends on the recurrence of oxidation in addition to mean telomere length.

Not verified in the article. Chronic telomeric oxidation and its effects on fibroblast senescence were studied, but the contribution of oxidation recurrence to age-related risk independently of mean telomere length was not tested.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Introduction; Results, Fig. 6; Discussion)

At equal telomere length and equal initial damage counts, repeated oxidation before completion of the preceding repair may cause overlapping repair processes and disproportionately increase telomere fragility.

Not verified in the article. The experiments support a contribution of repair intermediates to telomere fragility and senescence. They do not establish disproportionate fragility from a second oxidation pulse before repair completion at equal telomere length and equal initial damage counts.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Results, Figs. 3, 4 and 6; Discussion)

Overlapping repair processes could explain different donor responses to the same total damage burden.

Not verified in the article. The supplied studies do not test whether overlapping repair processes explain donor-specific responses to the same total damage burden.

The experiment must use paired fibroblasts from young and older donors.

Different experimental conditions. The study used telomerase-expressing BJ fibroblasts and derivatives deficient in OGG1, MUTYH or both. This model differs from paired fibroblast cultures from young and older donors.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Methods, Cell culture and cell lines generation)

Two pulses of 8-oxoguanine (8-oxoG) must be introduced locally.

Different experimental conditions. Localized telomeric 8-oxoG production was performed, but the protocols used an acute exposure or 18 exposures over 24 days rather than the specified two-pulse intervention.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Results, Figs. 1 and 6A; Methods, Cell treatments)

The experiment must compare short and long intervals between the two pulses.

Not verified in the article. No supplied study compares short and long intervals between two localized oxidation pulses.

The time to replication must be equalized between the interval conditions.

Not verified in the article. Replicating and quiescent cells were compared, including recovery before re-entry into growth conditions. This establishes replication dependence but does not equalize time to replication between two pulse-interval conditions.

Telomeric 8-oxo-guanine drives rapid premature senescence in the absence of telomere shortening (Results, Fig. 6d-g; Extended Data Fig. 10)

Newly introduced damage and residual repair intermediates must be measured independently.

Not verified in the article. Exonuclease-assisted fluorescence in situ hybridization measured single-strand break intermediates, while additional glycosylase treatment revealed lesions plus breaks after chronic exposure. These measurements do not independently identify damage newly introduced by the second pulse and intermediates remaining from the first.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Results, Fig. 4A-C and Fig. 6E-G; Methods, Exo-FISH)

One primary outcome must be the number of fragile telomeres per metaphase.

Matches this study. Fragile telomeres per metaphase were explicitly quantified after acute and chronic telomeric oxidation. The metaphase assays used transient p53 depletion to allow damaged cells to enter mitosis.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Results, Fig. 3B and Fig. 6I; Methods, Telomere FISH on metaphase spreads)

Another primary outcome must be the proportion of the original cells exhibiting persistent arrest after recovery.

Different experimental conditions. Cell counts, senescence-marker frequencies, cell-cycle profiles and colony formation assessed growth impairment and senescence. They do not provide the specified proportion of original fibroblasts remaining persistently arrested after recovery.

Telomeric 8-oxo-guanine drives rapid premature senescence in the absence of telomere shortening (Results, Fig. 1c-j and Fig. 6g; Methods, Growth analyses, Senescence-associated β-gal assay and Colony formation assay)

The outcome analysis must adjust for telomere length.

Not verified in the article. Bulk and shortest telomere lengths were measured to examine shortening after oxidation. This does not constitute outcome analysis adjusted for telomere length in the proposed donor and pulse-interval comparison.

Telomeric 8-oxo-guanine drives rapid premature senescence in the absence of telomere shortening (Results, Extended Data Fig. 8a-b; Methods, Telomere restriction fragment analysis and Telomere shortest length assay)

The overlapping-repair hypothesis is not supported if the outcome is fully determined by total damage burden or telomere length and the interval has no effect.

Not verified in the article. The supplied studies do not test whether total damage burden or telomere length fully accounts for both outcomes with no remaining interval effect. Consequently, they do not apply the proposed falsification criterion.

The hypothesis concerns residual epithelial strength after tear closure in aging tissue or elderly people at risk of repeated injury.

Not verified in the article. The clinical study includes predominantly elderly residents with skin tears, but does not assess residual epithelial strength after closure or susceptibility to repeat injury.

A pragmatic randomised controlled clinical study to evaluate the use of silicone dressings for the treatment of skin tears. (Sections 1.2, 1.8 and 2)

Aging may lengthen the interval between closure of a superficial skin defect and recovery of mechanical strength.

Not verified in the article. The supplied literature provides no verified age comparison of the interval between superficial defect closure and mechanical strength recovery.

Skin permeability may normalize before adhesion strength between skin layers recovers, creating an interval of vulnerability to repeated mechanical injury.

Not verified in the article. No supplied empirical result establishes that permeability normalizes before interlayer adhesion recovers or links this sequence to repeat mechanical injury.

With equivalent normalization of the barrier test, skin from elderly donors is predicted to reach the individual residual-strength threshold safe for repeat loading later than skin from young donors.

Not verified in the article. No supplied study compares young and elderly skin at equivalent barrier normalization to determine when an individual safe-loading strength threshold is reached.

Extending protection of the injured site until mechanical strength recovers is predicted to reduce the risk of another tear.

Different experimental conditions. The trial compares silicone and conventional dressings during healing. It does not compare protection durations determined by strength recovery or measure prevention of repeat tears.

A pragmatic randomised controlled clinical study to evaluate the use of silicone dressings for the treatment of skin tears. (Sections 1.3, 1.5, 1.9 and 2)

The experiment uses paired skin explants from young and elderly donors.

Different experimental conditions. The experiment treats existing wounds in long-term care residents rather than using paired explants from young and elderly donors.

A pragmatic randomised controlled clinical study to evaluate the use of silicone dressings for the treatment of skin tears. (Sections 1.1-1.3)

A standardized defect is created before assessing recovery.

Different experimental conditions. Participants entered with existing skin tears of different types; investigators did not create a standardized defect before monitoring recovery.

A pragmatic randomised controlled clinical study to evaluate the use of silicone dressings for the treatment of skin tears. (Sections 1.2 and 1.8; Table 2)

Independent young and elderly donors are compared under conditions of equivalent initial injury.

Different experimental conditions. The comparison is between dressing groups assigned by facility unit or floor, not independent young and elderly donor groups with equivalent initial injury.

A pragmatic randomised controlled clinical study to evaluate the use of silicone dressings for the treatment of skin tears. (Sections 1.3, 1.10 and 2; Table 2)

Barrier function and adhesion strength are measured on separate days after the standardized defect.

Not verified in the article. Serial assessments concern wound dimensions and clinical epithelial closure; neither barrier function nor interlayer adhesion strength is measured.

A pragmatic randomised controlled clinical study to evaluate the use of silicone dressings for the treatment of skin tears. (Sections 1.7-1.9)

Identical repeat loading is applied to independent samples.

Not verified in the article. The supplied literature contains no verified application of identical repeat mechanical loading to independent samples.

The interaction between age and the investigated factor must be checked in advance, and a confidence interval for the effect must be estimated; the investigated factor is not further specified.

Not verified in the article. Confidence intervals are reported for mean healing times, but no advance age-by-factor interaction check is described. The hypothesis leaves the investigated factor unspecified.

A pragmatic randomised controlled clinical study to evaluate the use of silicone dressings for the treatment of skin tears. (Section 1.10; Table 5)

A primary outcome is the interval between normalization of skin permeability and recovery of strength.

Different experimental conditions. The study measures wound healing and time to closure, not the interval between permeability normalization and strength recovery.

A pragmatic randomised controlled clinical study to evaluate the use of silicone dressings for the treatment of skin tears. (Sections 1.3 and 1.6-1.8; Table 5)

Another primary outcome is the proportion of repeat tears occurring within that interval.

Not verified in the article. The reported proportions concern healed wounds; the proportion of repeat tears during a barrier-strength recovery interval is not reported.

A pragmatic randomised controlled clinical study to evaluate the use of silicone dressings for the treatment of skin tears. (Sections 1.3 and 2)

The prediction is refuted if the elderly group has no reproducible interval between permeability normalization and strength recovery, or if that interval does not predict repeat tearing under identical loading.

Not verified in the article. No supplied study evaluates reproducibility of the proposed interval in elderly skin or its prediction of repeat tears under identical loading.

The stated scientific basis includes comparisons of skin-barrier recovery after disruption in humans and in an aging model.

Not verified in the article. The cited Ghadially study is absent from the supplied source texts. Human and aging-model comparisons of barrier recovery therefore cannot be verified here.

The stated scientific basis also includes a clinical comparison of dressings for skin tears in residents of long-term care institutions, with silicone dressings identified in the cited study title.

Matches this study. The primary clinical study compares soft silicone dressings with conventional dressings for skin tears in residents of two long-term care facilities.

A pragmatic randomised controlled clinical study to evaluate the use of silicone dressings for the treatment of skin tears. (Sections 1.1-1.5 and 2)

Axonal regrowth can stop at a continuous segment of weak Schwann cell support even when total c-Jun expression in an old nerve graft is normal.

Not verified in the article. Axons lacking Schwann cell guidance showed impaired progression and misdirection, but the experiments did not establish arrest at a weak-support segment in an old graft with normal total c-Jun.

Analysis of Schwann Cell Migration and Axon Regeneration Following Nerve Injury in the Sciatic Nerve Bridge (Results, Figures 6-9)

The competing model attributes the outcome solely to mean c-Jun expression, whereas the proposed model attributes a limiting role to the spatial continuity of local Schwann cell support.

Not verified in the article. The supplied studies do not directly discriminate spatial continuity from mean c-Jun expression by holding the total expression constant.

The stated scientific rationale is that increasing c-Jun in Schwann cells improved axonal regrowth in old mice and after prolonged denervation.

Matches this study. Schwann cell-specific c-Jun elevation restored axonal regeneration in aging mice and maintained regeneration through chronically denervated nerve stumps.

Failures of nerve regeneration caused by aging or chronic denervation are rescued by restoring Schwann cell c-Jun (Results, Figures 1D-F and 5A-C)

Construct linear Schwann cell tracks of equal length using cells from the same old donors across experimental conditions.

Different experimental conditions. The study constructed 5 mm micro-columns containing aligned rat Schwann cells, but did not use matched cells from the same old donors across the proposed spatial conditions.

Tissue Engineered Bands of Büngner for Accelerated Motor and Sensory Axonal Outgrowth (Materials and Methods, Hydrogel Micro-Column Fabrication; Primary Schwann Cell Culture)

Reversibly increase c-Jun in half of the Schwann cells used in the spatial distribution comparison.

Different experimental conditions. The intervention used genetically enhanced Schwann cell c-Jun expression, rather than reversible elevation restricted to half the cells in each track.

Failures of nerve regeneration caused by aging or chronic denervation are rescued by restoring Schwann cell c-Jun (Materials and methods, Transgenic mice; Results, Figure 1)

Compare three arrangements of the activated cells: a uniform distribution, a single proximal block, and a single distal block.

Not verified in the article. No supplied study compared uniform activation with a single proximal block and a single distal block.

Keep cell number, the c-Jun integral, adhesion, and the common axon source identical across the spatial distribution conditions.

Not verified in the article. Equal Schwann cell seeding and a central sensory-neuron compartment provide related controls, but identical c-Jun integrals, adhesion and axon source across the proposed spatial arrangements were not established.

c-Jun Reprograms Schwann Cells of Injured Nerves to Generate a Repair Cell Essential for Regeneration (Experimental Procedures, Microfluidic Chambers; Figure 5I-K)

Include fully active and inactive Schwann cell tracks as additional comparison groups.

Different experimental conditions. Comparisons included wild-type cells, c-Jun-null cells, rescued mutant cells and cell-free substrate, rather than fully active and inactive old-donor tracks accompanying the spatial comparison.

c-Jun Reprograms Schwann Cells of Injured Nerves to Generate a Repair Cell Essential for Regeneration (Figure 5I-K; Experimental Procedures, Microfluidic Chambers)

The primary outcome is the proportion of labeled motor axons that reach the exit chamber by day seven.

Different experimental conditions. The study counted retrogradely labeled neurons after regeneration over specified nerve distances. The week after tracer application was not a day-seven exit-chamber endpoint for labeled motor axons.

Failures of nerve regeneration caused by aging or chronic denervation are rescued by restoring Schwann cell c-Jun (Results, Figures 1D-E and 5A-B; Materials and methods, Retrograde labeling with Fluorogold)

Uniform distribution of activated Schwann cells is predicted to increase the proportion of axons reaching the exit chamber relative to both the proximal-block and distal-block arrangements.

Not verified in the article. Superior day-seven motor axon arrival with uniform c-Jun activation relative to both block arrangements was not tested in the supplied studies.

Similar axonal output across the spatial arrangements, accompanied by a precise interval, would refute spatial limitation in this model.

Not verified in the article. No supplied study assessed similar output across these spatial arrangements with an interval sufficiently precise to refute the proposed spatial limitation.

The Schwann cell donor is the independent experimental unit.

Different experimental conditions. The engineered-track study analyzed cultures or constructs as replicates; it did not identify the old Schwann cell donor as the independent experimental unit.

Tissue Engineered Bands of Büngner for Accelerated Motor and Sensory Axonal Outgrowth (Materials and Methods, Study Design and Statistical Analysis)

The experiment is a model of support for axonal growth, which defines the scope of its conclusions.

Matches this study. The study explicitly used an in vitro model to assess Schwann cell support and guidance of axonal growth, with transplantation efficacy reserved for future testing.

Tissue Engineered Bands of Büngner for Accelerated Motor and Sensory Axonal Outgrowth (Materials and Methods, Study Design and Statistical Analysis; Discussion)

Measure cell density along each track before adding axons, because unequal density along a track can produce a spurious spatial effect.

Different experimental conditions. Cell numbers and densities were examined in transverse nerve profiles at a specified distance from injury. This does not provide a longitudinal density map of every track before adding axons.

Failures of nerve regeneration caused by aging or chronic denervation are rescued by restoring Schwann cell c-Jun (Results, Figure 6; Materials and methods, Electron microscopy)

Randomize the allocation of experimental conditions.

Matches this study. Randomization of mouse groups for surgery and treatments was explicitly reported, although it concerned senolysis experiments rather than the proposed spatial comparison.

Senescent Schwann cells induced by aging and chronic denervation impair axonal regeneration following peripheral nerve injury (Materials and Methods, Wild type and transgenic mice)

Conceal group codes during outcome measurement.

Matches this study. Researchers received only the axonal image channel with a randomly coded identifier, explicitly concealing group information during image-based measurement.

Tissue Engineered Bands of Büngner for Accelerated Motor and Sensory Axonal Outgrowth (Materials and Methods, Microscopy and Data Acquisition)

Before the main experiment, use an independent pilot to determine reproducibility, the working duration, and the minimum distinguishable and biologically meaningful effect.

Not verified in the article. The supplied studies do not document an independent pilot establishing all three specified features: reproducibility, working duration and the minimum distinguishable and biologically meaningful effect.

Estimate the contrast and its confidence interval at the level of independent experimental units.

Different experimental conditions. The study reported construct-level means, standard errors and significance tests, rather than donor-level contrasts with confidence intervals for the proposed spatial comparison.

Tissue Engineered Bands of Büngner for Accelerated Motor and Sensory Axonal Outgrowth (Materials and Methods, Study Design and Statistical Analysis)

The experiment cannot distinguish the competing explanations if the intervention fails to separate the groups or if the interval allows substantial effects in both directions.

Not verified in the article. No supplied study specified the proposed inconclusive-result rule based on failed group separation or intervals allowing substantial effects in both directions.

A positive result would justify choosing a spatial arrangement for restoring cellular support in an old nerve graft.

Not verified in the article. The supplied evidence does not establish a result that selects among these spatial arrangements for restoring cellular support in an old nerve graft.

If the spatial limitation hypothesis is refuted, this approach does not advance to the next stage.

Not verified in the article. No supplied study applied a decision rule preventing advancement of this approach following refutation of spatial limitation.

The proposed biological system consists of aging cells.

Different experimental conditions. The closest DDB2 study used U2OS cells and immortalized epithelial and fibroblast lines, rather than an experimentally defined aging-cell system.

Global and transcription-coupled repair of 8-oxoG is initiated by nucleotide excision repair proteins (Methods: Cell lines; Results, Figures 1-6)

DDB2 assistance in removing oxidative DNA damage is proposed to depend on local DNA packing and interaction with OGG1.

Not verified in the article. DDB2 association with OGG1, DDB2-dependent OGG1 recruitment, and local chromatin decompaction were demonstrated. Dependence of DDB2 assistance on experimentally controlled local packing was proposed but not established.

Global and transcription-coupled repair of 8-oxoG is initiated by nucleotide excision repair proteins (Results, Figures 2 and 6; Discussion: Chromatin structure defines the critical players required for 8-oxoG processing)

DDB2 is predicted to enhance removal of 8-oxoguanine (8-oxoG) predominantly in densely packed nucleosomes, with a weaker effect in an open region of the same sequence.

Not verified in the article. DDB2 depletion delayed genomic 8-oxoG repair, and OGG1 recruitment showed different DDB2 dependence at telomeres and locally irradiated regions. Preferential enhancement in compact versus open chromatin of identical sequence was explicitly left unresolved.

Global and transcription-coupled repair of 8-oxoG is initiated by nucleotide excision repair proteins (Results, Figures 1d, 2f and 5e; Discussion, final paragraph before Figure 7)

Identical damaged reporters must be inserted into open and closed chromatin.

Different experimental conditions. Damage was generated at endogenous telomeres or in local nuclear regions using photosensitizers. These interventions do not constitute insertion of identical damaged reporters into open and closed chromatin.

Global and transcription-coupled repair of 8-oxoG is initiated by nucleotide excision repair proteins (Methods: Oxidative DNA damage generation; Results, Figures 1f and 5)

DDB2 restoration must be compared in the presence of OGG1 and under partial OGG1 deficiency in each chromatin state.

Different experimental conditions. The study examined OGG1 depletion and DDB2 depletion or knockout, including reciprocal effects on protein recruitment. It did not compare DDB2 restoration across OGG1-sufficient and partially deficient groups in both defined chromatin states.

Global and transcription-coupled repair of 8-oxoG is initiated by nucleotide excision repair proteins (Results, Figure 2c-f and Supplementary Figure 3; Methods: Knockout and knockdown cell line generation; siRNA transfections)

Initial 8-oxoG levels and local accessibility of the reporter region must be controlled.

Not verified in the article. The study checked initial oxidative lesion induction after sucrose-induced compaction and assessed chromatin condensation. It did not control initial 8-oxoG and local accessibility at paired, sequence-identical reporter regions during a DDB2 restoration experiment.

Oxidative stress triggers the preferential assembly of base excision repair complexes on open chromatin regions (Results: Recognition of 8-oxoG by OGG1 is not required for the recruitment of the protein to chromatin; Figure 6)

The kinetics of 8-oxoG removal must be measured separately for each chromatin state.

Different experimental conditions. Repair kinetics were measured in bulk genomic DNA after potassium bromate treatment. Measurements were not resolved separately for the proposed open and closed reporter chromatin states.

Global and transcription-coupled repair of 8-oxoG is initiated by nucleotide excision repair proteins (Figure 1c-d; Methods: Enzyme-based PFGE assay for 8-oxoG detection)

The yield of accurately repaired product must be measured separately for each chromatin state.

Different experimental conditions. A purified repair system measured nucleotide incorporation and ligated product formation from an abasic substrate on naked DNA. It did not measure accurately repaired 8-oxoG reporter yields separately in open and closed cellular chromatin.

Damage sensor role of UV-DDB during base excision repair (Results: Involvement of UV-DDB in base excision repair of oxidative damage in living cells; Figure 4a-b; Methods: Reconstituted human BER assay)

Equal enhancement of 8-oxoG removal by DDB2 on free DNA and in a densely packed region would require revision of the interaction model.

Not verified in the article. UV-DDB stimulated OGG1 on naked DNA, but a paired comparison of DDB2 enhancement on free DNA and densely packed substrates was not performed. Free-DNA stimulation alone does not meet the proposed equal-enhancement criterion.

Damage sensor role of UV-DDB during base excision repair (Figure 1b-d; Discussion, final paragraph before Figure 5)

Persistence of the DDB2 enhancement after OGG1 loss, without compensation by another glycosylase, would require revision of the interaction model.

Not verified in the article. OGG1 depletion prolonged DDB2 retention and altered ligase-complex recruitment. The study did not test persistence of DDB2-enhanced lesion removal after OGG1 loss while excluding compensation by another glycosylase.

Global and transcription-coupled repair of 8-oxoG is initiated by nucleotide excision repair proteins (Results, Figure 2c-d and Figure 4h-i)

The experiment uses epidermal models from donors aged 25-40 and 70-85 years.

Different experimental conditions. The study examined skin biopsies from donors aged 20-32, 35-47 and 51-71 years, alongside childhood foreskin samples and keratinocyte cultures. These differ from epidermal models representing the specified 25-40 and 70-85-year groups.

Dermal stiffness governs the topography of the epidermis and the underlying basement membrane in young and old human skin (Materials and Methods, section 4.1; Results, sections 2.2-2.3.)

The models receive three identical ultraviolet A (UVA) exposures, with blinded assessment after the three exposures.

Different experimental conditions. Reconstructed skin received single exposures or daily exposures for five consecutive days to mixed UVA/UVB radiation. Three identical UVA-only exposures with subsequent blinded assessment are not documented.

Different Oxidative Stress Response in Keratinocytes and Fibroblasts of Reconstructed Skin Exposed to Non Extreme Daily-Ultraviolet Radiation (Results, DUVR source and Damage in reconstructed skin morphology after DUVR exposure; Figure 1c.)

The hypothesis predicts that aged epidermis progressively loses its ability to withstand the next challenge during a series of identical UVA exposures.

Not verified in the article. Repeated irradiation caused pronounced epidermal and dermal morphological damage, but progressive loss of resistance to the next challenge specifically in aged epidermis was not tested.

Different Oxidative Stress Response in Keratinocytes and Fibroblasts of Reconstructed Skin Exposed to Non Extreme Daily-Ultraviolet Radiation (Results, Damage in reconstructed skin morphology after DUVR exposure; Figure 1b-c.)

An age-related increase in the labile iron fraction sustains membrane oxidation after UVA exposure, including in the dark, and thereby reduces resistance to subsequent exposures.

Not verified in the article. The abstract reports immediate UVA-induced labile iron release and iron-associated nuclear membrane damage in human fibroblasts. It does not establish an age-related iron increase, sustained membrane oxidation in darkness, or consequent resistance loss during repeated epidermal exposures.

Ultraviolet A Radiation-Induced Immediate Iron Release Is a Key Modulator of the Activation of NF-κB in Human Skin Fibroblasts (Abstract displayed on the article page.)

After each UVA exposure, the models receive an iron-binding agent for brief iron binding, with washout before the next exposure.

Not verified in the article. Iron chelation is mentioned, but the available abstract does not verify brief treatment after each exposure followed by washout before the next exposure.

Ultraviolet A Radiation-Induced Immediate Iron Release Is a Key Modulator of the Activation of NF-κB in Human Skin Fibroblasts (Abstract displayed on the article page.)

The comparison groups receive either the iron-saturated analogue of the iron-binding agent or vehicle after each UVA exposure, with washout before the next exposure.

Not verified in the article. The supplied studies do not document the paired iron-saturated analogue and vehicle control groups with treatment after every UVA exposure and washout before the next.

The experiment compares the number of exposure cycles until persistent loss of barrier function.

Different experimental conditions. The repeated-exposure experiment assessed morphology and matrix metalloproteinase-1 production after a fixed regimen. It did not measure the number of cycles required for persistent barrier-function loss.

Different Oxidative Stress Response in Keratinocytes and Fibroblasts of Reconstructed Skin Exposed to Non Extreme Daily-Ultraviolet Radiation (Figure 1c-d; Materials and Methods, Histology, immunolabelling and staining and MMP1 ELISA assay.)

The comparison of cycles until persistent barrier-function loss is made at comparable initial damage.

Not verified in the article. No supplied study compares cycles to persistent barrier failure between age groups at comparable initial damage.

The experiment measures labile iron and oxidized lipids.

Not verified in the article. The study reports increased epidermal lipid peroxide concentrations, with data not shown, but does not report paired labile iron measurements. The required measurement of both endpoints is therefore unverified.

Different Oxidative Stress Response in Keratinocytes and Fibroblasts of Reconstructed Skin Exposed to Non Extreme Daily-Ultraviolet Radiation (Results, Exposure of reconstructed skin to DUVR led to oxidative stress in epidermal keratinocytes and dermal fibroblasts.)

Brief iron binding is predicted to reduce the difference between aged and young epidermis in barrier preservation during repeated UVA exposures.

Not verified in the article. The supplied literature does not test whether brief iron binding reduces the young-old difference in epidermal barrier preservation during repeated UVA exposures.

Persistence of the age difference in resistance to repeated exposures after removal of excess labile iron and reduction of oxidation would refute the hypothesis.

Not verified in the article. No supplied experiment tests whether the age difference in repeated-exposure resistance persists after verified removal of excess labile iron and reduction of oxidation.

The hypothesis would also be refuted if the iron-saturated analogue produced the same effect on barrier preservation as the iron-binding agent.

Not verified in the article. No supplied experiment compares barrier preservation by the iron-binding agent and its iron-saturated analogue as the specified falsification control.

The hypothesis proposes that functionally significant cyclobutane pyrimidine dimers (CPDs) are the principal lesions accumulating in the aging basal layer and limit epidermal barrier restoration more strongly than 6-4 photoproducts.

Not verified in the article. The supplied studies do not establish preferential accumulation of functionally important CPDs in an aging basal layer or their greater causal effect on barrier restoration. The mouse study establishes lesion-dependent effects on other skin outcomes.

Age dependence is to be tested in paired series of cells from young and elderly donors, with the experiment described as using four paired skin cultures and comparing independent young and elderly donors.

Different experimental conditions. The closest intervention study used 8- to 10-week-old Xpa-knockout mice, rather than four paired skin cultures from independent young and elderly human donors.

Photorepair of Either CPD or 6-4PP DNA Lesions in Basal Keratinocytes Attenuates Ultraviolet-Induced Skin Effects in Nucleotide Excision Repair Deficient Mice (Materials and Methods: Mouse Lines; Chronic UV Irradiation)

The experimental groups must receive CPD-specific photolyase alone, 6-4-photoproduct-specific photolyase alone, both photolyases together, or inactive enzyme as the control.

Different experimental conditions. Separate transgenic CPD-photolyase and 6-4-photolyase groups were compared with mice expressing neither enzyme. This substitutes an enzyme-absent control for inactive enzyme and omits the combined-photolyase group.

Photorepair of Either CPD or 6-4PP DNA Lesions in Basal Keratinocytes Attenuates Ultraviolet-Induced Skin Effects in Nucleotide Excision Repair Deficient Mice (Materials and Methods: Mouse Lines; Results and Figure 1)

The comparison of selective lesion removal must use the same initial ultraviolet dose, and the comparison between young and elderly donors must use equal initial damage.

Not verified in the article. The mouse comparisons used common ultraviolet B doses within each protocol: 20 J/m² daily for chronic exposure or 200 J/m² for acute exposure. Equal initial damage between young and elderly donors was not tested, so the complete condition is unverified.

Photorepair of Either CPD or 6-4PP DNA Lesions in Basal Keratinocytes Attenuates Ultraviolet-Induced Skin Effects in Nucleotide Excision Repair Deficient Mice (Materials and Methods: Chronic UV Irradiation; Acute Irradiation)

Light activation must be equalized across the experimental groups.

Matches this study. The mouse protocol specifies the same three-hour photoreactivation exposure immediately after ultraviolet irradiation, using four white lamps positioned 40 cm above the mice. This matches the light-standardization component in a different model.

Photorepair of Either CPD or 6-4PP DNA Lesions in Basal Keratinocytes Attenuates Ultraviolet-Induced Skin Effects in Nucleotide Excision Repair Deficient Mice (Materials and Methods: UV Radiation and Photoreactivation of Mice)

Removal of CPDs and removal of 6-4 photoproducts must be verified separately to confirm the specificity of the interventions.

Matches this study. The study separately immunodetected CPDs and 6-4 photoproducts with lesion-specific antibodies to confirm repair of the respective targets by the expressed photolyases.

Photorepair of Either CPD or 6-4PP DNA Lesions in Basal Keratinocytes Attenuates Ultraviolet-Induced Skin Effects in Nucleotide Excision Repair Deficient Mice (Materials and Methods: Immunohistochemistry for the Detection of Photolesions; Results, reference to Supplementary Figure S1)

The damaged surface layer must be removed before assessing barrier restoration.

Not verified in the article. No supplied study describes experimental removal of the damaged surface layer followed by assessment of barrier restoration. Shaving mice before irradiation does not satisfy this intervention.

The primary outcome is the time required for permeability to return to its baseline value after removal of the damaged surface layer.

Different experimental conditions. The closest intervention study measured epidermal thickness, proliferation, apoptosis, inflammation and metalloproteinase activity. It did not measure time to recovery of baseline permeability after surface-layer removal.

Photorepair of Either CPD or 6-4PP DNA Lesions in Basal Keratinocytes Attenuates Ultraviolet-Induced Skin Effects in Nucleotide Excision Repair Deficient Mice (Materials and Methods; Results, Figures 1-4)

Selective CPD removal is predicted to improve epidermal barrier re-formation and reduce the age gap in barrier resilience more strongly than selective removal of 6-4 photoproducts.

Different experimental conditions. CPD removal prevented ultraviolet-induced hyperplasia, whereas 6-4-photoproduct removal reduced it less completely. This supports differential lesion effects, but hyperplasia suppression is a different outcome from barrier re-formation and reduction of an age gap.

Photorepair of Either CPD or 6-4PP DNA Lesions in Basal Keratinocytes Attenuates Ultraviolet-Induced Skin Effects in Nucleotide Excision Repair Deficient Mice (Results: Effects of Basal Keratinocyte-Specific Photoremoval; Figure 1)

The analysis must include an advance check of the interaction between age and the factor under investigation and estimation of the confidence interval for the effect.

Not verified in the article. The supplied studies provide no advance analysis of an age-by-intervention interaction with a confidence interval for the proposed barrier effect. The mouse study used one-way analysis of variance with Bonferroni comparisons.

With intervention specificity confirmed, equivalent effects of the two individual photolyases or a greater benefit from removing 6-4 photoproducts would refute the prediction.

Not verified in the article. Neither equivalence of the individual photolyases nor superiority of 6-4-photoproduct removal was tested for the specified age-dependent barrier outcome. Benefits of both enzymes for mouse apoptosis and inflammation do not constitute this falsification test.

The stated scientific basis includes measurements of ultraviolet lesion excision at different genomic regions in human cells.

Matches this study. Hu and colleagues mapped excision of both lesion classes across genomic regions in human fibroblasts, including normal cells and cells deficient in either global or transcription-coupled repair.

Genome-wide analysis of human global and transcription-coupled excision repair of UV damage at single-nucleotide resolution (Results: The XR-seq procedure; Figures 1-4; Materials and methods: Cell lines)

The stated scientific basis also includes transgenic models used to study differences between photolesions and the role of removing them from the basal layer.

Matches this study. The supplied primary study used K14-driven photolyase transgenes to compare removal of the two lesion classes specifically in basal keratinocytes. It directly establishes this background component; the cited 2006 study itself is available only as a reference within the supplied material.

Photorepair of Either CPD or 6-4PP DNA Lesions in Basal Keratinocytes Attenuates Ultraviolet-Induced Skin Effects in Nucleotide Excision Repair Deficient Mice (Materials and Methods: Mouse Lines; Results, Figures 1-3)

The submitted text states that the proposed predictions concerning epithelial resilience in elderly donors were not evaluated in the work cited as the scientific basis.

Not verified in the article. Hu and colleagues studied fibroblast excision repair rather than epithelial resilience in elderly donors, confirming the stated limitation for that paper. The other cited foundational paper lacks a supplied full text, so the statement about both cited works cannot be fully verified.

Genome-wide analysis of human global and transcription-coupled excision repair of UV damage at single-nucleotide resolution (Materials and methods: Cell lines; Results; SOURCE-1 References, reference 19)

The hypothesis concerns aging tissues exposed to repeated oxidative stress.

Not verified in the article. Neither supplied primary study examines aging tissues under repeated oxidative stress; their experiments use defined clustered lesions in cultured cells or cell extracts.

The distance between lesions on opposing strands and the order of repair initiation determine whether simultaneous initiation is more harmful than sequential initiation, with a pause potentially beneficial for closely spaced lesions.

Different experimental conditions. Lesion spacing and orientation affected incision hierarchy and double-strand break kinetics in three-lesion substrates. The study compared substrate configurations with endogenous processing kinetics, rather than experimentally assigned simultaneous and sequential initiation.

Hierarchy of lesion processing governs the repair, double-strand break formation and mutability of three-lesion clustered DNA damage (Results, Figures 2 and 3; Discussion)

A short delay in removal of the second base is predicted to reduce double-strand breaks specifically at closely spaced opposing lesions.

Different experimental conditions. Retarded incision at the second abasic site was associated with slower double-strand break formation at particular close spacings and orientations. This concerns cleavage at an existing abasic site, not a controlled short delay in removing the second base; substantial break formation still occurred.

Hierarchy of lesion processing governs the repair, double-strand break formation and mutability of three-lesion clustered DNA damage (Results, subsection on retardation of incision of the single AP site; Figure 3)

The experiment must compare double-stranded substrates with lesions at different distances in extracts from young and older donors.

Different experimental conditions. Double-stranded oligonucleotides with different lesion spacings were tested in nuclear extracts from exponentially growing Chinese hamster ovary CHO-K1 cells. These were not extracts from young and older donors.

Hierarchy of lesion processing governs the repair, double-strand break formation and mutability of three-lesion clustered DNA damage (Materials and Methods, Preparation of nuclear extract and Repair assay; Table 1)

Controlled enzyme addition must establish simultaneous and sequential initiation of lesion processing.

Not verified in the article. Neither study uses timed enzyme addition to assign simultaneous versus sequential initiation at opposing lesions. Enzyme combinations, substrate pretreatment and endogenous processing hierarchies do not establish that intervention.

Simultaneous and sequential processing must be compared at equal total enzyme activity.

Not verified in the article. The supplied studies do not compare simultaneous and sequential processing at equal total enzyme activity. Fixed extract amounts or measurements of enzyme expression do not verify this control.

The primary outcomes are the fraction of accurately restored duplexes and the fraction of molecules split into two parts.

Different experimental conditions. The study quantified rejoined labelled strands and the fraction of double-strand break products by electrophoresis. Rejoining one labelled strand does not establish accurate restoration of the entire damaged duplex, and these outcomes were not compared between controlled initiation schedules.

Hierarchy of lesion processing governs the repair, double-strand break formation and mutability of three-lesion clustered DNA damage (Materials and Methods, Repair assay and Assessment of DSB induction during repair; Figures 1-3)

The direction of the effect must be confirmed using a cellular reporter.

Different experimental conditions. A luciferase reporter in mouse fibroblasts demonstrated spacing-dependent effects of opposing tetrahydrofuran lesions and effects of reducing Apex1 expression. It did not confirm the direction of an experimentally imposed delay in second-base removal; sequential repair was a mechanistic interpretation.

DNA repair of clustered lesions in mammalian cells: involvement of non-homologous end-joining (Results, Figures 1 and 2; Discussion, Figure 4)

The stated falsification criterion is that the sequential scheme has no advantage if lesion distance and processing order do not interact in determining accurate product yield.

Not verified in the article. Neither supplied study tests the interaction between lesion distance and experimentally assigned processing order on accurate product yield, or applies the proposed falsification criterion.

The experiment involves older people with clinically equivalent skin sites for repeated dressing attachment.

Different experimental conditions. The cohort included predominantly older adults, but testing used a marked forearm site for experimental tape stripping rather than clinically equivalent sites for repeated dressing attachment.

Demographic factors associated with skin barrier function in a large population-based study (Results, Figure 1; Materials and Methods, Study participants and Baseline barrier permeability.)

Repeated adhesive removal is associated with disruption of the skin barrier.

Matches this study. Sequential application and removal of adhesive tape strips increased transepidermal water loss, directly demonstrating barrier disruption from repeated stripping.

Demographic factors associated with skin barrier function in a large population-based study (Materials and Methods, Barrier integrity; Results, Figure 3 and Table 1.)

Participants are randomized to rotation of dressing attachment sites or the usual attachment schedule.

Different experimental conditions. The available abstract describes a randomized within-subject comparison of saline, petrolatum, alcohol, and no topical agent during adhesive removal. It does not compare site rotation with the usual attachment schedule.

Topical normal saline, alcohol, and petrolatum for MARSI: A randomized controlled trial (Abstract, Methods.)

Dressing material, change frequency, and tape area are identical in the rotation and usual-schedule groups.

Not verified in the article. The supplied studies do not establish identical dressing material, change frequency, and tape area between rotation and usual-schedule groups because that comparison is absent.

Rotation is hypothesized to protect the skin only when the usual interval before reuse of the same site is shorter than that site's individual barrier recovery time.

Not verified in the article. No supplied experiment tests whether rotation protects only when the usual reuse interval is shorter than the individual site's barrier recovery time.

Two smaller damaged sites may be as unfavorable as one large damaged site, so relocating damage alone does not establish protection.

Not verified in the article. No supplied study compares the combined burden of two smaller damaged sites with one larger damaged site or separates redistribution of injury from overall protection.

Baseline individual barrier recovery speed is assessed at a separate skin site during a routine dressing change.

Different experimental conditions. Recovery was measured at the experimentally stripped forearm site after 24 ± 2 hours. This differs from assessing baseline individual recovery speed at a separate site during a routine dressing change.

Demographic factors associated with skin barrier function in a large population-based study (Materials and Methods, Baseline barrier permeability and Barrier recovery; Discussion, Limitations.)

Water loss is measured before each new contact with the attachment material, after a standard acclimatization period.

Different experimental conditions. Participants acclimatized for 15-20 minutes, and water loss was measured at baseline, during sequential stripping in sets of five, and at recovery follow-up. Measurement before every new dressing contact was not reported.

Demographic factors associated with skin barrier function in a large population-based study (Materials and Methods, Epidermal function measurements, Barrier integrity and Barrier recovery.)

The primary outcome is the total area of erosions across both attachment sites integrated over time during two weeks; rotation is predicted to reduce this total area-time relative to the usual schedule.

Different experimental conditions. The study integrated water-loss measurements against tape-strip number. That outcome differs from total erosion area across two attachment sites integrated over two weeks, and no rotation effect on erosion area-time was tested.

Demographic factors associated with skin barrier function in a large population-based study (Materials and Methods, Dynamic barrier function; Results, Figure 3.)

The same rescue-care rule is applied in both groups at the first signs of clinically significant injury.

Not verified in the article. The supplied material does not document a common rescue-care rule triggered by the first clinically significant injury in rotation and usual-schedule groups.

If rotation merely relocates damage without reducing the total erosion area-time, the functional hypothesis is rejected.

Not verified in the article. No supplied study tests the rejection criterion that merely relocating injury, with unchanged total erosion area-time, fails the functional hypothesis.

The effect of rotation is predicted to depend on barrier recovery before the next attachment, with individual recovery speed predicting the result; an effect independent of recovery would not support the timing mechanism.

Not verified in the article. Individual recovery measurements were not linked to a rotation intervention, its protective effect, or recovery before the next attachment. The proposed timing-dependent prediction therefore remains untested in the supplied studies.

In the context of age-related accumulation of CAG repeat expansions, strengthening the interaction of FAN1 with the repair complex is proposed to reduce expansions at individual loci while preserving correction of simple mismatches elsewhere in the genome and overall mismatch repair (MMR) activity.

Not verified in the article. MLH1 binding contributes to FAN1-mediated CAG stabilization, but preservation of overall MMR and simple-mismatch correction is unverified. Increased 6-thioguanine resistance instead indicates reduced MMR activity in FAN1-overexpressing U2OS cells.

FAN1 controls mismatch repair complex assembly via MLH1 retention to stabilize CAG repeat expansion in Huntington’s disease (Results, Figures 2-4; Discussion)

The experiment must use neurons carrying a CAG reporter.

Different experimental conditions. The introduced HTT exon 1 CAG construct and FAN1 variant comparisons were studied in U2OS cells. Patient-derived medium spiny neurons carried endogenous expanded HTT and underwent FAN1 knockdown, rather than the proposed neuronal reporter experiment.

FAN1 controls mismatch repair complex assembly via MLH1 retention to stabilize CAG repeat expansion in Huntington’s disease (Figures 1J-1M, 3 and 4F; Methods, Cell culture and manipulation; iPSC culture and manipulation)

The experiment must compare FAN1 variants with intact versus weakened binding to MLH1.

Matches this study. Full-length FAN1 and SPYF-motif mutants were compared for MLH1 binding and CAG stabilization. This intervention component was explicitly tested in U2OS cells, with the neuronal-system difference remaining.

FAN1 controls mismatch repair complex assembly via MLH1 retention to stabilize CAG repeat expansion in Huntington’s disease (Figures 2G-2H and 3A-3B)

FAN1 variants with disabled nuclease activity must be examined separately.

Matches this study. The nuclease-inactive D960A variant was examined separately and combined with the MLH1-binding-defective F129A variant. These experiments distinguish catalytic and binding contributions, although they used U2OS cells.

FAN1 controls mismatch repair complex assembly via MLH1 retention to stabilize CAG repeat expansion in Huntington’s disease (Figures 1F-1J and 3C-3G)

The experiment must include a paired test of correction of a single simple mismatch.

Different experimental conditions. Paired T/G mismatch and CAG-extrusion repair assays were performed in HeLa nuclear extracts using FAN1-derived peptides, knockout cells and MLH1 variants. They were not paired with longitudinal CAG expansion measurements in neurons expressing the specified FAN1 variants.

Disruption of protein–protein interaction hotspots in the C-terminal domain of MLH1 confers mismatch repair deficiency (Figures 2, 3 and 5; Materials and methods, In vitro repair assays)

Expression of the FAN1 variants must be verified.

Matches this study. Immunoblots verified FAN1 variant expression, including comparable full-length FAN1 and F129A/D960A expression. This control was performed in the U2OS variant experiments.

FAN1 controls mismatch repair complex assembly via MLH1 retention to stabilize CAG repeat expansion in Huntington’s disease (Figures 2G and 3C; Results, FAN1 SPYF motif and nuclease activity)

The primary outcomes must be the frequency and size of new CAG expansions under preserved overall MMR activity.

Not verified in the article. The study measured repeat-length trajectories and expansion rates, but did not establish the specified joint outcome of new-expansion frequency and size under preserved overall MMR activity.

FAN1 controls mismatch repair complex assembly via MLH1 retention to stabilize CAG repeat expansion in Huntington’s disease (Figures 1J-1M, 3 and 4D; Methods, Somatic instability assay)

Repeat lengths must be measured with correction for baseline mosaicism.

Different experimental conditions. Mouse analyses used repeat length in ear tissue at weaning and adjusted instability comparisons for inherited CAG size. This differs from correcting neuronal reporter measurements for the starting distribution of repeat lengths.

Promotion of somatic CAG repeat expansion by Fan1 knock-out in Huntington’s disease knock-in mice is blocked by Mlh1 knock-out (Figures 1-4; Materials and methods, Htt CAG repeat somatic instability index and expansion index parameters; Statistics)

A reduction in expansions that requires a general decline in MMR activity refutes the proposed selective effect.

Not verified in the article. Reduced MMR activity accompanying FAN1-mediated stabilization challenges selectivity, but the study did not establish that a general MMR decline is necessary for suppression in the complete proposed neuronal test.

FAN1 controls mismatch repair complex assembly via MLH1 retention to stabilize CAG repeat expansion in Huntington’s disease (Figure 4D; Discussion, MMR activity and 6-thioguanine resistance)

The analysis must account for death of cells with long repeats; disappearance of the reduction in expansions after this adjustment refutes the proposed selective effect.

Not verified in the article. No supplied study adjusted expansion suppression for preferential death of cells with long repeats. Drug-survival assays and apoptosis measurements do not provide this repeat-length-dependent cell-loss control.

The experiment uses microvessels made from cells of young and older donors, with vessels from each donor included in both alternation conditions.

Different experimental conditions. The study uses human aortic and umbilical vein endothelial cell cultures, described in its limitations as immortalized cell lines, rather than microvessels from young and older donors represented in both conditions.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Antibodies and reagents; Cell culture; Discussion.)

The hypothesis proposes that the number of reoxygenations, in addition to the total hypoxic dose, determines persistent endothelial dysfunction through repeated transitions between hypoxia and normoxia.

Not verified in the article. The study investigates cadherin-dependent permeability during intermittent hypoxia, but does not establish that reoxygenation count determines persistent dysfunction independently of total hypoxic dose.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Establishment of cell models; Results: CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression.)

With equal time spent at each oxygen level, more frequent alternation between hypoxia and normoxia is predicted to increase residual permeability in an aged microvessel after cycling has stopped.

Not verified in the article. The reported permeability comparisons do not test frequency at equal oxygen exposure in aged microvessels after cycling stops. The null difference between intermittent hypoxia and control therefore does not refute this prediction.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Establishment of cell models; Results: CDH1 significantly reduces HAEC permeability; Figures 2A and 5D.)

Microvessels from each donor must be randomly assigned to two different numbers of alternations between hypoxia and normoxia.

Different experimental conditions. Cell cultures receive 2, 4, 6, 8, 10 or 12 cycles for model selection, followed by a selected six-cycle model. Random allocation of each donor's microvessels to two alternation counts is not described.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Establishment of cell models.)

The two alternation conditions must have identical oxygen extremes, cumulative durations at each oxygen level, flow and culture conditions.

Different experimental conditions. Each cycle comprises 30 minutes at 1% oxygen and 60 minutes at 21% oxygen, so increasing cycle count also increases cumulative phase durations. The required equal-dose comparison under matched flow is absent.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Establishment of cell models.)

Constant normoxia must serve as the control condition.

Matches this study. The study includes a normal-culture control alongside the intermittent-hypoxia groups, matching the constant-normoxia control component.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Cell culture; Results: Expression and localization of the CDH1 protein in HAECs under CIH and ox-LDL conditions; Figure 1.)

Actual oxygen levels must be measured directly at the cells; short pulses that fail to reach the intended amplitude make the experiment uninterpretable.

Not verified in the article. An oxygen sensor is used to characterize oxygen partial pressure in culture medium and select phase durations. Direct measurement at the cells and amplitude validation for both proposed frequency profiles are not documented.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Establishment of cell models.)

The primary outcome must be albumin permeability measured after one day of normoxia shared by the experimental groups.

Different experimental conditions. Permeability is assessed using 70 kDa fluorescent dextran in Transwell inserts with a 30-minute assay after modeling. Albumin permeability after a shared day of normoxia is not measured.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: FITC-dextran for endothelial permeability.)

A second independent study must vary the speed of the oxygen transition while keeping the number of cycles fixed.

Not verified in the article. The supplied literature contains no independent experiment varying oxygen transition speed while holding cycle count fixed.

The analysis must test the interaction between donor age and alternation frequency while accounting for baseline permeability and vessel origin.

Not verified in the article. The study describes one-way group comparisons, without an age-by-frequency interaction adjusted for baseline permeability and vessel origin.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Statistical analysis.)

The analysis must aggregate observations by donor, with fields of view not counted as independent biological replicates.

Not verified in the article. Experiments are performed in triplicate and repeated at least three times, but donor-level aggregation and the treatment of fields of view as nested observations are not specified.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Statistical analysis.)

An absence of a frequency effect on permeability under equal dose profiles and comparable viability would refute the prediction.

Not verified in the article. Viability is assessed during model selection, but no permeability frequency comparison combines equal dose profiles with comparable viability. The reported null result therefore does not meet the proposed falsification criterion.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Establishment of cell models; Results: CDH1 significantly reduces HAEC permeability.)

If the effect is explained solely by transition speed or cell loss, the conclusion about the number of transitions must be narrowed.

Not verified in the article. The study acknowledges limitations of total-leakage measurements, but does not separate effects of transition count, transition speed and cell loss.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Methods: Establishment of cell models; Discussion: limitations.)

The proposed test specifically addresses the role of repeated oxygen transitions in persistent barrier dysfunction, while the general benefits or harms of hypoxia are outside its scope.

Different experimental conditions. The study addresses cadherin-mediated endothelial protection under intermittent hypoxia and oxidized lipoprotein exposure, rather than persistent barrier dysfunction specifically attributable to repeated oxygen transitions.

CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression under chronic intermittent hypoxia (Introduction; Results: CDH1 reduces endothelial cell permeability by enhancing CDH5 membrane expression; Discussion.)

The scientific rationale distinguishes the cellular responses to sustained and intermittent hypoxia, while recognizing that findings about hypoxia-inducible factor (HIF) or systemic apnea alone do not establish a frequency effect on the barrier.

Not verified in the article. The cited sustained-versus-intermittent hypoxia study is not supplied as readable article text. The available full article discusses hypoxia-inducible factors and apnea but does not empirically establish this response comparison or a barrier frequency effect.

The experiment is proposed, and its results have not yet been obtained.

Not verified in the article. The submitted record describes a proposed experiment with results not yet obtained. No supplied primary report documents completion of that experiment; its proposed status alone is not evidence of scientific novelty.

The experiment uses a standardized tympanic membrane perforation model in old animals to investigate the age-related decline in recovery of sound conduction.

Different experimental conditions. Standardized perforations were studied in mice aged 6-8 weeks, rather than in old animals undergoing an investigation of age-related functional recovery.

Tracking cell layer contribution during repair of the tympanic membrane (Materials and Methods: Perforation of the tympanic membrane.)

The layers of the tympanic membrane recover at different times during perforation healing, so closure of the defect alone does not establish recovery of sound transmission.

Matches this study. The epithelial bridge preceded repair by mesenchymal and mucosal layers, followed by vascular invasion and remodeling. This establishes asynchronous repair and distinguishes initial closure from tissue restoration; sound transmission itself was not measured.

Tracking cell layer contribution during repair of the tympanic membrane (Results: Figures 1 and 3-8; Discussion.)

A temporary scaffold with radially oriented fibers is applied to the perforated tympanic membrane of old animals.

Different experimental conditions. Radial scaffolds were fabricated and studied with cultured human cells. They were not applied to perforated tympanic membranes in old animals.

Mimicking the Human Tympanic Membrane: The Significance of Scaffold Geometry (Results 2.1 and 2.4.3; Experimental Section: Biological Characterization.)

The experiment compares patches with radially oriented fibers, patches with randomly oriented fibers, and spontaneous healing.

Different experimental conditions. The comparison comprised radial, circumferential, combined radial-circumferential, and plain electrospun scaffolds. It did not include the proposed three-arm animal comparison with spontaneous healing.

Mimicking the Human Tympanic Membrane: The Significance of Scaffold Geometry (Results 2.1; Figure 2C.)

The radial and randomly oriented patches are matched for thickness, mass, degradation time, and initial elasticity.

Different experimental conditions. Scaffold architectures had different measured stiffnesses and thicknesses. Matching radial and random patches simultaneously for thickness, mass, degradation time, and initial elasticity was not demonstrated.

Mimicking the Human Tympanic Membrane: The Significance of Scaffold Geometry (Results 2.4.1; Figure 5A; Discussion.)

Radially oriented scaffold fibers are hypothesized to direct deposition and orientation of the tympanic membrane's own connective tissue during healing, thereby improving restoration of vibration after scaffold resorption.

Different experimental conditions. Scaffold filaments guided cultured-cell alignment and collagen deposition. The causal sequence from guided endogenous repair in old animals to improved vibration after resorption was not tested; scaffold degradation was identified as future work.

Mimicking the Human Tympanic Membrane: The Significance of Scaffold Geometry (Results 2.4.3: Collagen Deposition; Figure 7; Discussion.)

Young adult animals are included, with equal perforation sizes across ages, to test whether the oriented scaffold reduces the age-related difference in recovery of sound conduction.

Not verified in the article. The supplied studies do not compare old and young adult animals with equal perforation sizes to test whether oriented scaffolds reduce an age-related recovery difference.

The orientation of endogenous collagen is assessed blindly.

Not verified in the article. Endogenous collagen organization was visualized during spontaneous mouse repair, but blinded assessment of collagen orientation in the proposed scaffold experiment is not documented.

Epimorphic regeneration in the mammalian tympanic membrane (Results: The TM displays scar-free repair; Figure 2d; Methods: Immunofluorescence and Imaging.)

Tympanic membrane thickness is measured blindly.

Not verified in the article. Membrane-layer thickness was quantified, but the supplied methods do not establish blinded measurement.

Tracking cell layer contribution during repair of the tympanic membrane (Figure 1I-K; Materials and Methods: Quantification and statistics.)

The fraction of closed defects is assessed blindly.

Not verified in the article. The study reported closure of observed perforations from day 7 onward, but blinded assessment of the fraction closed is not documented.

Epimorphic regeneration in the mammalian tympanic membrane (Results: Injury to the TM induces a robust proliferative response; Figure 1.)

The primary outcome is the velocity of the malleus handle after complete patch resorption, measured at a specified sound pressure within a preselected frequency band.

Different experimental conditions. Umbo velocity was measured in fresh temporal bones from 9-week-old rats at 80 dB over 1-10 kHz before and immediately after perforation. Recovery after two weeks was assessed using auditory brainstem responses, rather than malleus-handle velocity after complete patch resorption.

Evaluation of acoustic changes in and the healing outcomes of rat eardrums with pars tensa and pars flaccida perforations (Methods 2.2-2.5; Results 3.1 and 3.3; Figures 2 and 4.)

The prediction is refuted if endogenous collagen orientation changes but vibration transmission is equivalent at equal defect closure.

Not verified in the article. No supplied study tests vibration equivalence at equal defect closure after a demonstrated change in endogenous collagen orientation and complete scaffold resorption.

The proposed experiment uses aging fibroblasts with a confirmed deficiency of the XRCC4-LIG4 complex.

Different experimental conditions. The study used p53-null mouse embryonic fibroblasts with genetically deleted XRCC4, verified by Western blotting. It did not establish aging fibroblasts with an age-associated deficiency of the XRCC4-LIG4 complex.

Distinct roles of XRCC4 and Ku80 in non-homologous end-joining of endonuclease- and ionizing radiation-induced DNA double-strand breaks (Materials and Methods: Cells; Results: Lack of XRCC4 reduces the efficiency and fidelity of NHEJ)

End-joining accuracy is proposed to determine the quality of the first division of an aging cell.

Not verified in the article. None of the supplied studies directly connects end-joining accuracy to the quality of the first division of an aging cell.

Accelerated joining of double-strand breaks in aging fibroblasts may leave more deletions when accuracy is the limiting factor rather than joining speed.

Not verified in the article. The supplied experiments do not test whether accelerating break closure in aging fibroblasts increases deletions when repair accuracy is limiting. Measurements of repair efficiency or product accumulation in other models do not establish this causal relationship.

Deficiency of the XRCC4-LIG4 complex is proposed to limit end-joining accuracy.

Matches this study. XRCC4 deletion, which disables the functional XRCC4-LIG4 complex, increased deletion lengths and error-prone joining of complementary ends. This supports the proposed fidelity mechanism, although the experiments used embryonic fibroblasts rather than aging cells.

Distinct roles of XRCC4 and Ku80 in non-homologous end-joining of endonuclease- and ionizing radiation-induced DNA double-strand breaks (Results: Lack of XRCC4 reduces the efficiency and fidelity of NHEJ, Figure 2B-D; Lack of XRCC4 or Ku80 enhances error-prone rejoining of complementary DNA ends)

Brief restoration of the XRCC4-LIG4 complex is proposed to increase the proportion of precise junctions in the deficient cells.

Different experimental conditions. Adding recombinant Lig4-XRCC4 restored end joining and close end alignment in depleted Xenopus egg extracts. This substitutes a cell-free complementation assay for brief restoration in deficient aging fibroblasts and does not measure an increased proportion of precise sequences.

Structural role for DNA Ligase IV in promoting the fidelity of non-homologous end joining (Results: Characterization of Lig4 DNA-binding mutants, Figure 1C; DNA-binding by Lig4 is required for SR synapsis, Figure 2C)

Induce one brief break with compatible ends during the G1 phase of the cell cycle.

Different experimental conditions. The reporter contained two inverted I-SceI sites and permitted both single-site cleavage with compatible ends and double cleavage with incompatible ends. Cells were incubated for 48 hours after nuclease-plasmid transfection, without a specified G1-restricted single-break pulse.

Distinct roles of XRCC4 and Ku80 in non-homologous end-joining of endonuclease- and ionizing radiation-induced DNA double-strand breaks (Materials and Methods: NHEJ assay; Figure 1B; Results: reporter assay description)

Turn off the nuclease immediately after cleavage.

Not verified in the article. Immediate nuclease shutoff after cleavage is not documented in any supplied study. Introducing previously cleaved DNA into cells or extracts does not reproduce this intracellular cleavage-and-shutoff condition.

Compare restoration of the XRCC4-LIG4 complex with an inactive ligase control and a vector control.

Different experimental conditions. Purified-protein experiments included the catalytically defective LIG4 K273R mutant and measured end pairing. They did not compare restoration in deficient aging fibroblasts against both inactive-ligase and vector controls.

Bridging of double-stranded breaks by the nonhomologous end-joining ligation complex is modulated by DNA end chemistry (Materials and Methods: Protein purification; Results and Discussion; Figure 1D)

Measure initial cleavage and the number of unrepaired molecules separately.

Not verified in the article. No supplied study separately measures initial cleavage and unrepaired molecules for the proposed nuclease-induced test. Radiation-break measurements and assays using pre-cleaved substrates do not supply those measurements under the specified conditions.

The primary outcome is the proportion of precisely restored sequences among all initially cleaved molecules, including lost alleles in the denominator.

Different experimental conditions. Precise or directly ligated products were expressed as proportions of recovered, amplifiable junctions. The denominator did not include all initially cleaved molecules and lost alleles, and primer placement limited the deletions that could be recovered.

The fidelity of the ligation step determines how ends are resolved during Nonhomologous end joining (Results: Ability of cellular NHEJ to bypass terminal mispairs, Figure 2C; Methods: Substrates and NHEJ assays; Sequencing)

Faster break closure without an increase in the proportion of precise junctions refutes the proposed improvement in accuracy.

Not verified in the article. None of the supplied studies applies the specified rejection criterion to XRCC4-LIG4 restoration in aging fibroblasts, using repair kinetics and the precise-repair proportion among all initially cleaved molecules.

The hypothesis concerns aging neurons, and the experiment uses directly converted neurons, with the primary outcomes assessed in nondividing neurons.

Different experimental conditions. The neuronal experiments used hippocampal slices from juvenile mice and primary hippocampal cultures from neonatal mice. These are different models from aging, directly converted neurons, although they provide relevant neuronal evidence.

Parp1 hyperactivity couples DNA breaks to aberrant neuronal calcium signalling and lethal seizures (Materials and Methods: Electrophysiology; Cell culture; Figures 3-6.)

XRCC1 structure determines the duration of PARP1 retention at damage sites in aging neurons.

Different experimental conditions. Full-length XRCC1 and the 161-406 truncation differed in suppression of PARP1 chromatin accumulation in U2OS cells. PARP1 mobility was also examined in mouse embryonic fibroblasts. Neither experiment established XRCC1-dependent retention duration in aging neurons.

XRCC1 prevents toxic PARP1 trapping during DNA base excision repair (Results: XRCC1 protein complexes prevent excessive PARP1 engagement and activity during BER; Figure 4A-C; Figure S2.)

During neuronal aging, impaired assembly of the XRCC1 complex with gap-filling and ligation enzymes may become a limiting factor in repair, leaving repair unfinished and thereby prolonging PARP1 retention at damage sites.

Different experimental conditions. The study links XRCC1 assembly of DNA polymerase β and DNA ligase III to suppression of PARP1 trapping. However, it identifies excessive PARP1 engagement as a cause of impaired repair and break accumulation, followed by NAD+ depletion and reduced dissociation. It does not test age-related assembly loss or establish unfinished repair as the initiating cause of prolonged retention in neurons.

XRCC1 prevents toxic PARP1 trapping during DNA base excision repair (Results: XRCC1 protein complexes prevent excessive PARP1 engagement and activity during BER; Figure 5A-B; Discussion.)

Compare full-length XRCC1 with an XRCC1 variant that has lost a selected interaction.

Matches this study. The study compares full-length XRCC1 with a variant lacking its BRCT II domain, which mediates interaction with DNA ligase IIIα, and demonstrates loss of ligase recruitment. This matches the intervention component, although the experiments used non-neuronal cells and the deletion also affected XRCC1 retention.

Damage response of XRCC1 at sites of DNA single strand breaks is regulated by phosphorylation and ubiquitylation after degradation of poly(ADP-ribose) (Results: The BRCT II domain of XRCC1 is necessary for the damage response of LigIIIα; Figures 1-2.)

Match XRCC1 expression, localization, and the initial number of breaks between the full-length XRCC1 and interaction-deficient variant groups.

Not verified in the article. Expression of the recombinant proteins and recruitment of the truncation into chromatin were examined. The supplied methods do not establish simultaneous matching of expression, localization and initial break numbers between the full-length and interaction-deficient groups.

XRCC1 prevents toxic PARP1 trapping during DNA base excision repair (Figure 4A-C; STAR Methods: siRNA and transfection; Chromatin retention assay & immunoblotting.)

Measure PARP1 retention and the kinetics of strand repair.

Different experimental conditions. The study measures PARP1 chromatin retention and mobility together with DNA break accumulation during methyl methanesulfonate exposure. These experiments do not reproduce the proposed paired retention and strand repair kinetic measurements in directly converted neurons; the truncation comparison measures break accumulation after treatment rather than a repair recovery time course.

XRCC1 prevents toxic PARP1 trapping during DNA base excision repair (Figures 2C-D and 4B-C; Figure S2; STAR Methods: Live cell imaging; Alkaline comet assays.)

The primary outcomes are residual single-strand breaks and the time required for electrical activity to return to its baseline level.

Different experimental conditions. The neuronal study measures seizure-like events and stimulus-evoked presynaptic calcium responses after Parp1 deletion or inhibition. It does not measure the proposed combination of residual single-strand breaks and time for electrical activity to return to baseline after the XRCC1 interface comparison.

Parp1 hyperactivity couples DNA breaks to aberrant neuronal calcium signalling and lethal seizures (Figures 3-6; Materials and Methods: Electrophysiology; SyGCaMP6f imaging.)

If the mutant and full-length XRCC1 eliminate breaks equally despite a confirmed difference in the selected interaction, the tested interaction interface does not explain the effect.

Not verified in the article. No supplied study implements the specified neuronal test in which confirmed loss of the selected interaction is evaluated against equal break removal by mutant and full-length XRCC1 as the decisive criterion for rejecting that interface explanation.

The experiment examines age-related impairment of cardiac recovery after standardized myocardial infarction in young adult and old mice.

Different experimental conditions. Young and old mice were compared during cardiac aging. The infarction experiment concerned a separate non-aging model; recovery after standardized infarction was not compared between young adult and old mice.

Age-associated loss of lymphatic vessels promotes cardiac inflammation (Results, Figures 1-2 and 5; Extended Data Figure 6)

The rationale is that the cardiac lymphatic system participates in the resolution of inflammation in myocardial infarction models.

Matches this study. The study demonstrated lymphatic transport of cardiac immune cells to mediastinal lymph nodes after infarction and enhanced inflammatory clearance following VEGF-C treatment.

The cardiac lymphatic system stimulates resolution of inflammation following myocardial infarction (Results, Figures 2-6; Supplemental Figure 9)

The hypothesis proposes that stimulating lymphatic capillary growth after injury to old myocardium improves diastolic relaxation only when lymphatic drainage from the injured area functions, including a preserved connection to an outflow vessel; whether capillary growth without this connection is sufficient for a functional benefit in old age is the question being tested.

Different experimental conditions. Lyve1 deletion impaired leukocyte uptake and clearance despite preserved lymphangiogenesis, with subsequent cardiac deterioration. This differs from testing outflow-vessel continuity and fluid drainage as prerequisites for improved relaxation in injured old hearts.

The cardiac lymphatic system stimulates resolution of inflammation following myocardial infarction (Results, Figures 3, 6-7; Supplemental Figure 9)

In both age groups after myocardial infarction, a local lymphangiogenic stimulus must be compared with vehicle under both preserved and selectively restricted lymphatic drainage.

Different experimental conditions. Young mice received local VEGF-C Cys156Ser, vehicle, MAZ-51, or a VEGF-C-neutralizing antibody in separate groups. The experiment did not cross stimulus versus vehicle with selective drainage restriction in both age groups.

Impact of Lymphangiogenesis on Cardiac Remodeling After Ischemia and Reperfusion Injury (Methods, Animals and Gelatin-Based Hydrogel Preparation; Results, Figures 5-7)

The experiment must include a sham-operation control.

Matches this study. Sham-operated controls underwent passage of a suture under the coronary artery without ligation.

The cardiac lymphatic system stimulates resolution of inflammation following myocardial infarction (Methods, MI; Figure 5)

Initial infarct size and coronary perfusion must be matched between the comparison groups.

Not verified in the article. Separate acute cohorts had similar infarct sizes and areas at risk at 24 hours. Matching coronary perfusion across the proposed age-by-treatment-by-drainage groups was not established; vessel density measurements do not establish perfusion matching.

Impact of Lymphangiogenesis on Cardiac Remodeling After Ischemia and Reperfusion Injury (Methods, Infarct Size Analysis; Results, Figure 8A-E)

Lymphatic network density must be measured.

Matches this study. Cardiac lymphatic density was quantified and compared across vehicle, lymphangiogenic treatment, and inhibitory treatment groups.

Impact of Lymphangiogenesis on Cardiac Remodeling After Ischemia and Reperfusion Injury (Methods, Immunofluorescence; Results, Figure 5A-B)

The rate of inert-tracer clearance into the draining lymph node must be measured to assess lymphatic drainage.

Different experimental conditions. A 2000-kDa fluorescent dextran tracer was injected into the cardiac apex and measured in blood after 30 minutes. This measures a different destination and endpoint from tracer-clearance rate into the draining lymph node.

Impact of Lymphangiogenesis on Cardiac Remodeling After Ischemia and Reperfusion Injury (Methods, Lymph Vessel Function; Results, Figure 5D)

The primary outcome at 4 weeks is the left ventricular relaxation time constant, measured at comparable heart rate and loading conditions.

Different experimental conditions. The aged-mouse treatment experiment assessed E/E′ after 8 weeks. It did not measure the left ventricular relaxation time constant at 4 weeks after infarction under matched heart rate and loading.

Age-associated loss of lymphatic vessels promotes cardiac inflammation (Figure 5o; Methods, Echocardiography)

The magnitude of the therapeutic effect must be compared between old and young adult animals, and whether drainage quality explains the difference between ages must be tested separately.

Not verified in the article. No supplied study compared post-infarction therapeutic effect sizes between young adult and old mice and separately tested drainage quality as the explanation for age differences.

Improved relaxation despite confirmed absence of drainage would refute the proposed necessity of drainage.

Not verified in the article. No supplied experiment assessed improved relaxation following lymphangiogenic stimulation in injured old myocardium while independently confirming absent drainage.

Absence of a relaxation benefit with preserved drainage would fail to confirm the expected benefit of the lymphangiogenic stimulus.

Not verified in the article. VEGFC increased lymphatic density without attenuating age-related diastolic dysfunction. However, this was an aging experiment without infarction or independently verified preserved drainage, so it does not implement the specified failure-to-confirm criterion.

Age-associated loss of lymphatic vessels promotes cardiac inflammation (Results, VEGFC reduces macrophage accumulation but does not preserve cardiac diastolic function; Figure 5k-o)

The experiment concerns nerve injury and recovery in old animals, with autophagy manipulated in Schwann cells.

Different experimental conditions. Schwann-cell autophagy was manipulated after injury, but the nerve experiments used mice aged 6-8 weeks and postnatal cell preparations, rather than old animals undergoing recovery.

Schwann cell autophagy, myelinophagy, initiates myelin clearance from injured nerves (Materials and methods: Models to study Schwann cell myelin breakdown; Results: Genetic inactivation of autophagy.)

Following injury, Schwann cells dismantle their own myelin through autophagy.

Matches this study. Myelin-containing autophagosomes, flux measurements, and pharmacological and Schwann-cell-specific genetic inhibition support autophagic breakdown of the cells' own myelin after injury.

Schwann cell autophagy, myelinophagy, initiates myelin clearance from injured nerves (Results: Figures 1-4; Pharmacological inhibition of autophagy impairs demyelination; Genetic inactivation of autophagy.)

Enhancing myelinophagy is hypothesized to be beneficial until the distal nerve segment is cleared of old myelin.

Not verified in the article. Five days of nerve growth factor treatment enhanced early myelin clearance and subsequent regeneration in young rats. Benefit specifically lasting until complete distal clearance was not tested.

Nerve growth factor activates autophagy in Schwann cells to enhance myelin debris clearance and to expedite nerve regeneration (Results: Figures 1-6 and 12-13; Methods: Sciatic nerve crush model and drug treatments.)

Continued activation after clearance and axon return is hypothesized to delay new myelin sheath formation, so stopping myelinophagy after clearance should accelerate recovery of nerve conduction.

Not verified in the article. No supplied study tested whether continuing activation after verified clearance and axon return delays remyelination, or whether stopping activation then accelerates conduction recovery.

All comparison groups must undergo identical nerve compression.

Matches this study. The injured treatment and saline-control groups received the same sciatic nerve compression protocol: vascular clips for 2 minutes at 30 g force. This matches the injury-standardization component.

Nerve growth factor activates autophagy in Schwann cells to enhance myelin debris clearance and to expedite nerve regeneration (Materials and methods: Sciatic nerve crush model and drug treatments.)

The experiment must compare time-limited activation of autophagy in Schwann cells, prolonged activation, and a control without activation.

Different experimental conditions. The study compared five-day systemic rapamycin, an autophagy inhibitor, and vehicle treatment, with an additional sham group. It lacked a prolonged-activation arm and Schwann-cell-specific activation.

Autophagy Promotes Peripheral Nerve Regeneration and Motor Recovery Following Sciatic Nerve Crush Injury in Rats (Materials and Methods: Drug Treatment.)

The switch-off time for time-limited activation must be selected using an independent pilot series.

Not verified in the article. No supplied study selected the activation switch-off time from an independent pilot series assessing the proposed clearance window.

Actual removal of the old myelin sheath and autophagic flux must be verified using a label for old myelin and an autophagic flux reporter.

Different experimental conditions. The study used labeled exogenous myelin debris in cultured cells and a tandem fluorescent flux reporter in a separate oxidative-stress assay. These do not verify removal of labeled pre-existing sheaths and flux in the proposed old-animal experiment.

Nerve growth factor activates autophagy in Schwann cells to enhance myelin debris clearance and to expedite nerve regeneration (Methods: Myelin phagocytosis assays using primary Schwann cells; Detection of autophagic flow; Results: Figures 5 and 14.)

Genetic loss of ATG7 must be used to test dependence on autophagy.

Matches this study. Schwann-cell-specific Atg7 deletion impaired myelin breakdown and blocked its acceleration by lithium and ceramide, directly testing dependence on ATG7.

Schwann cell autophagy, myelinophagy, initiates myelin clearance from injured nerves (Results: Genetic inactivation of autophagy; Figures 4-6, especially Figure 6F.)

The primary outcome must be conduction velocity in the recovered nerve at week 8.

Not verified in the article. None of the supplied studies used recovered-nerve conduction velocity at week 8 as the primary outcome.

The assessment of nerve conduction recovery must account for the number and caliber of returning axons.

Different experimental conditions. Axon numbers, diameter categories, and myelin g-ratios were assessed at week 6, but they were not used to account for returning axons in a nerve-conduction recovery analysis.

Autophagy Promotes Peripheral Nerve Regeneration and Motor Recovery Following Sciatic Nerve Crush Injury in Rats (Results: Autophagy Promotes Axonal Regeneration and SC Remyelination; Figure 5; Methods: Behavioral Analysis.)

The proposed beneficial window is considered absent if, with equal myelin clearance and equal axon numbers, continuous activation restores conduction no worse than brief activation within the specified equivalence range.

Not verified in the article. No supplied study performed the specified equivalence comparison between continuous and brief activation under equal clearance and equal axon numbers.

After the same injury, transitional cells derived from alveolar and airway epithelium may differ in their ability to form a sealed alveolar barrier despite similar KRT8 expression.

Not verified in the article. Both origins contribute to the Krt8-positive state after bleomycin injury, but their barrier function at comparable KRT8 expression was not compared.

Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis (Results, Transcriptional convergence of alveolar and airway stem cells; Figures 6-7.)

The alternative hypothesis proposes complete functional interchangeability of cells from the two epithelial sources after transition.

Not verified in the article. No supplied study establishes complete functional interchangeability between the two origins after transition; transcriptional convergence does not establish functional equivalence.

The stated scientific rationale includes convergence of different epithelial lineages into a Krt8-positive transitional state after mouse lung injury and the detection of similar cells in human fibrotic lungs.

Matches this study. Lineage tracing supports alveolar and airway contributions to the mouse Krt8-positive intermediate, and human transcriptomic comparisons and staining identify related cells in fibrotic lungs.

Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis (Results, Figures 6-7 and 9; lineage-tracing and human-tissue analyses.)

The stated scientific rationale includes induction of a transitional fibroblast state by the accumulation of intermediate epithelial cells in alveolar injury models, together with disruption of tissue architecture when transitional states were eliminated.

Not verified in the article. Wang and colleagues examine epithelial transitional cells, macrophages and activated fibroblasts. They do not establish the specified transitional fibroblast state together with architectural disruption following elimination of transitional states.

Regulation of epithelial transitional states in murine and human pulmonary fibrosis (Results, Figures 2-5; Discussion, Figure 8.)

The experiment must include alveolar-derived and airway-derived transitional cells from both young and old mouse donors.

Different experimental conditions. The study primarily uses mice aged 6-10 weeks and alveolar type 2-derived intermediates, rather than both epithelial origins from young and old donors.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (Experimental Model and Subject Details, Mouse Models; Results, Figures 1-4.)

The two epithelial sources must be independently labeled before injury.

Matches this study. Separate Sftpc-CreERT2 and Sox2-CreERT2 reporter experiments label alveolar and airway sources before injury, with a tamoxifen chase exceeding 21 days.

Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis (Methods, Lineage tracing experiments; Figure 7.)

Isolated intermediate cells from the compared sources must have equivalent viability.

Not verified in the article. Dead cells were excluded during sorting, but equivalent viability of alveolar-derived and airway-derived intermediate populations was not established.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (Method Details, Lung tissue dissociation and flow cytometry.)

Barriers must be constructed using equal numbers of cells on the same matrix, with both origins placed in a shared environment.

Different experimental conditions. Defined numbers of alveolar type 2 cells were cultured with stromal cells in Matrigel organoids. This substitutes an organoid differentiation assay for equal-number barriers from both origins in a shared environment.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (Experimental Model and Subject Details, Primary 3D Lung organoid co-culture.)

Lineage purity and the fraction of the surface covered by cells must be checked.

Not verified in the article. Lineage labeling was characterized, but the combined verification of isolated-population lineage purity and barrier surface coverage was not performed.

Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis (Methods, Lineage tracing experiments and Uninjured labeling; Figure 7.)

An intact alveolar epithelial layer must serve as the reference.

Not verified in the article. No supplied experiment uses an intact alveolar epithelial layer as the reference for the proposed permeability comparison.

The primary outcome is albumin permeability through a fully covered layer on day seven.

Different experimental conditions. Permeability was assessed during in vivo injury at day 4, while day-7 cultures were assessed for differentiation. Neither measures albumin permeability through a fully covered reconstructed layer on day seven.

Regulation of epithelial transitional states in murine and human pulmonary fibrosis (Results, Figure 2E-F; Figures 3 and 5E.)

The donor animal must be the independent experimental unit.

Matches this study. For longitudinal expression modeling, independent samples were mice rather than individual cells. This matches animal-level replication as a methodological component, but was not applied to the proposed barrier assay.

Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis (Methods, Analysis of the whole-lung data set, Time course differential expression analysis.)

Among cells from old donors, the predicted result is lower albumin leakage through alveolar-derived layers than through airway-derived layers.

Not verified in the article. No supplied study reports lower albumin leakage from alveolar-derived than airway-derived layers from old donors.

Precisely established equality between the two origins, with lineage labels retained, would exclude epithelial origin as a criterion for selecting cells in this model.

Not verified in the article. No study tests sufficiently precise functional equality between origins while confirming retained lineage labels.

Because sorting may select different transitional stages, cells must be matched using several proteins and their injury history.

Not verified in the article. Multiple markers and differentiation timing were characterized, but sorted intermediates from both origins were not matched by several proteins and injury history before a barrier comparison.

Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis (Results, Figures 6-8; Methods, Flow cytometry.)

A positive result would support selecting a cell source for alveolar barrier restoration, whereas refutation would prevent this approach from advancing to the next stage.

Not verified in the article. The supplied studies do not implement the proposed decision to select a cell source after a positive barrier result or halt the approach after refutation.

Experimental conditions must be allocated randomly.

Matches this study. Mice were randomly assigned to saline or bleomycin groups. Random allocation is reported as a component, although the proposed barrier conditions were not tested.

Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis (Methods, Experimental design and animal treatment.)

Group codes must be concealed during measurement.

Matches this study. The person counting cells was blinded to specimen genotype and condition. This matches measurement blinding as a component, not blinding of an albumin permeability assay.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (Quantification and Statistical Analysis.)

Before the main experiment, an independent pilot must establish reproducibility, the working time point, and the minimum detectable and biologically meaningful effect.

Not verified in the article. Pilot experiments informed animal sample size, but an independent pilot establishing reproducibility, timing, and detectable and biologically meaningful permeability effects is not documented.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (Quantification and Statistical Analysis.)

The contrast between groups and its confidence interval must be estimated at the level of independent experimental units.

Not verified in the article. Mouse-level expression modeling and confidence intervals for smoothed trajectories do not establish a donor-level barrier contrast with its confidence interval.

Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis (Methods, Time course differential expression analysis; Figures 6 and 8.)

The experiment must be considered unable to distinguish the explanations if the intervention fails to separate the groups or if the confidence interval permits substantial effects in both directions.

Not verified in the article. No supplied study applies the specified inconclusive-result rule based on failure to separate groups or confidence intervals admitting substantial effects in both directions.

The proposed aging phenotype is delayed filling of a single-nucleotide gap in a subset of older donors, assessed using fibroblast extracts.

Different experimental conditions. The study used transformed mouse embryonic fibroblast extracts with targeted polymerase deletions, rather than fibroblast extracts from older donors with a selective gap-filling phenotype.

DNA Polymerases β and λ Mediate Overlapping and Independent Roles in Base Excision Repair in Mouse Embryonic Fibroblasts (Results and Discussion, Generation of the double knockout cell line; Materials and Methods, Cell lines and Transformation of primary mouse embryonic fibroblast cells.)

Insufficient DNA polymerase β (POLB) may delay single-nucleotide gap filling and completion of repair after normal base removal.

Different experimental conditions. POLB-null extracts showed strongly deficient base excision repair. Complete gene deletion substitutes for age-associated insufficiency, and the experiments did not isolate delayed gap filling after verified normal base removal.

DNA Polymerases β and λ Mediate Overlapping and Independent Roles in Base Excision Repair in Mouse Embryonic Fibroblasts (Results and Discussion, Comparison of extract-mediated BER for wild-type and knockout mouse cell lines; Figure 2.)

An increased number of breaks is predicted to indicate a benefit from restoring POLB only when ligase activity is preserved.

Not verified in the article. No supplied experiment tested whether break abundance predicts a response to POLB restoration specifically when ligase activity is preserved.

Fibroblast extracts must be compared on three substrates: the initial lesion, a preformed single-nucleotide gap, and a break ready for ligation.

Different experimental conditions. The assays used uracil-containing and 8-oxoguanine-containing duplexes. They did not compare the required lesion, preformed single-nucleotide gap, and ligation-ready break substrates.

DNA Polymerases β and λ Mediate Overlapping and Independent Roles in Base Excision Repair in Mouse Embryonic Fibroblasts (Materials and Methods, In vitro BER assay; Figure 2A-B.)

POLB must be restored to the physiological range.

Not verified in the article. The supplied experiments do not document restoration of POLB to a defined physiological range.

An inactive enzyme must be included as a control for POLB restoration.

Not verified in the article. An inactive POLB restoration control is not documented. The full article's immunoprecipitation controls address protein interactions, not enzymatic rescue.

The primary outcome is the amount of full-length accurate product relative to the gap substrate, measured under conditions of equal ligation of the control break.

Different experimental conditions. The study quantified fully repaired, ligated products from lesion-containing duplexes relative to wild-type extract activity. It did not establish the specified accurate-product yield relative to a gap substrate under equal control-break ligation.

DNA Polymerases β and λ Mediate Overlapping and Independent Roles in Base Excision Repair in Mouse Embryonic Fibroblasts (Figure 2A-C; Materials and Methods, In vitro BER assay.)

POLB is ruled out as the bottleneck if there is no selective delay in gap filling or if adding POLB does not increase the accurate final product.

Not verified in the article. No supplied experiment applied the proposed exclusion criterion combining selective gap-filling kinetics with the accurate final-product response to added POLB.

The experiment uses an alveolar epithelium chip made from cells of elderly donors to model aged epithelium.

Different experimental conditions. The experiments used mouse alveolar progenitors in Matrigel organoids and adult mice, rather than alveolar epithelium chips derived from elderly human donors.

Alveolar epithelial progenitor cells require Nkx2-1 to maintain progenitor-specific epigenomic state during lung homeostasis and regeneration (Methods: Ethical compliance and animals; Standard organoid plating and maintenance.)

Wnt-responsive alveolar type 2 (AT2) progenitors participate in alveolar regeneration, and their spatial distribution determines which alveolar regions regenerate and the extent of surface restoration.

Not verified in the article. Wnt-dependent progenitor growth and spatial relationships between AT2 cells and Wnt-expressing fibroblasts were demonstrated. The causal claim that progenitor placement determines the location and area of restored epithelium was not tested.

Hypercapnia alters stroma-derived Wnt production to limit β-catenin signaling and proliferation in AT2 cells (Results: Activation of βcat-signaling rescues AT2 progenitor activity during hypercapnia; Figures 6-8.)

Equal, spatially separated microinjuries are created on the chip.

Different experimental conditions. Influenza infection and hyperoxia produced lung injury in mice, with regions subsequently classified by damage severity. These interventions do not reproduce equal, spatially separated microinjuries on a chip.

Temporal and spatial staging of lung alveolar regeneration is determined by the grainyhead transcription factor Tfcp2l1 (Results and Figures 2-3; Methods: Influenza infection; Hyperoxia treatment and lung assessment program.)

Cells with confirmed Wnt responses are placed either uniformly near several defects or together in a single compact cluster.

Not verified in the article. None of the supplied studies compared uniform placement of confirmed Wnt-responsive cells near several defects with placement in one compact cluster.

The uniform-placement and compact-cluster groups have identical total numbers of the placed cells, matrix, and flow orientation.

Not verified in the article. No supplied experiment held total cell number, matrix, and flow orientation identical between the two specified placement groups.

The experiment includes a control with ordinary AT2 cells.

Not verified in the article. An ordinary AT2 control accompanying the proposed Wnt-responsive-cell placement experiment was not reported. Other genetic or culture controls do not establish this comparison.

Cell clones are tracked independently.

Different experimental conditions. Fluorescent labeling distinguished clonal mouse organoids and identified expanding epithelial clones in mice. Independent clone tracking in the specified elderly-donor chip placement experiment was not performed.

Alveolar epithelial progenitor cells require Nkx2-1 to maintain progenitor-specific epigenomic state during lung homeostasis and regeneration (Results: In vitro gene editing of AEP-derived alveolar organoids via AAV6.2FF-Cre; Figures 5 and 7.)

The primary outcome is the fraction of the originally damaged surface that has no local tracer leakage after two weeks.

Not verified in the article. No supplied study measured the fraction of the originally damaged surface without local tracer leakage at two weeks.

Uniform placement is predicted to restore a larger sealed fraction of the originally damaged surface than placement in a single compact cluster.

Not verified in the article. Greater restoration of sealed surface with uniform placement than with one compact cluster was neither demonstrated nor directly tested.

Differences in the number of growing organoids alone are insufficient to support the prediction.

Not verified in the article. The supplied studies assessed organoid growth, differentiation, or tissue morphology, but did not apply the proposed requirement that organoid counts alone cannot establish the placement prediction.

Equal surface restoration between the groups would refute the prediction if the difference in cell-placement geometry remains maintained.

Not verified in the article. No supplied study tested equal surface restoration while verifying persistence of the difference between uniform and clustered placement.

The proposed test concerns preservation of the regenerative reserve of aged limbal and corneal epithelial tissue.

Different experimental conditions. Aged mouse limbal and corneal epithelia were studied after a single injury, including diminished activation of label-retaining cells. Preservation of aged tissue reserve through the proposed donor-culture graft experiment was not tested.

Limbal epithelial stem cell activity and corneal epithelial cell cycle parameters in adult and aging mice (Methods 2.3, 2.7-2.8; Results 3.5; Figure 7; Table 2)

The spatial proximity of surviving limbal clones is proposed to determine the durability of the corneal epithelium, with aging of the limbal epithelium potentially increasing the dependence of repair on the distance between surviving clones.

Not verified in the article. Clonal migration, long-term epithelial replacement and density-driven movement were investigated. The causal effect of spacing between surviving limbal clones, and its modification by aging, was not established.

Peripheral (not central) corneal epithelia contribute to the closure of an annular debridement injury (Results, Figures 2-4 and 6; Materials and Methods, Computational Model of Corneal Epithelial Wound Healing)

Labeled cultures from one donor must be assembled into two spatial configurations, uniform distribution and several dense islands, and transferred onto paired donor corneas.

Not verified in the article. No supplied study assembled labeled cultures from one donor into uniform and dense-island configurations for transfer onto paired donor corneas.

The spatial configurations must be compared at the same total cell number and the same proportion of clonogenic limbal cells.

Not verified in the article. The supplied studies do not compare the two graft configurations while holding both total cell number and clonogenic limbal cell proportion constant.

Area, cell composition and carrier must be matched between the two spatial configurations.

Not verified in the article. Matching area, cell composition and carrier between the specified graft configurations is not documented.

Uniform distribution of clonogenic limbal cells in the graft is predicted to preserve the corneal surface better than their arrangement in several dense islands.

Not verified in the article. No supplied experiment reports better corneal surface preservation with uniformly distributed clonogenic graft cells than with several dense islands.

Spatial distribution of the graft at an unchanged cell number is predicted to preferentially improve repeated repair in corneas with low regenerative reserve.

Not verified in the article. Conditional Lhx2 deletion impaired repair after repeated debridement, supporting a connection between epithelial regenerative capacity and repeated repair. Preferential rescue of low-reserve corneas by graft redistribution at unchanged cell number was not tested.

LIM Homeobox Domain 2 Is Required for Corneal Epithelial Homeostasis (Results, Lhx2 cKO Mice Showed Impaired Corneal Epithelial Wound Healing; Figure 5)

The experimental corneas must undergo a first and a second superficial defect to assess repeated repair.

Matches this study. Two successive central corneal epithelial wounds were explicitly performed to assess repeated repair. This component was tested in young mice, without the proposed aged donor-cornea graft comparison.

Differentiation Trajectory of Limbal Stem and Progenitor Cells under Normal Homeostasis and upon Corneal Wounding (Methods 2.2; Results 3.2; Figures 1 and 4)

The primary outcome is the proportion of continuous epithelium seven days after the second superficial defect, accounting for the number of active clones; uniform placement is predicted to yield a higher proportion.

Different experimental conditions. The study measured wound area after repeated injury and collected tissues 13 days after the second wound. It did not measure the specified seven-day continuous-epithelium outcome adjusted for active clone number or compare graft configurations.

Differentiation Trajectory of Limbal Stem and Progenitor Cells under Normal Homeostasis and upon Corneal Wounding (Results 3.1-3.2; Figures 2-4)

The prediction is refuted if uniform placement provides no reproducible advantage despite a confirmed difference between the spatial configurations.

Not verified in the article. No supplied study verified the two specified graft configurations and assessed whether uniform placement lacked a reproducible advantage. Null findings from other comparisons cannot satisfy this refutation criterion.

The stated scientific basis includes observations after transplantation of autologous cultures, including an association between culture composition and transplantation outcome.

Not verified in the article. The article cites Rama and colleagues’ transplantation study, but the supplied material does not include that study's methods and results establishing the culture-composition association. A bibliographic citation alone cannot verify this requirement.

Differentiation Trajectory of Limbal Stem and Progenitor Cells under Normal Homeostasis and upon Corneal Wounding (Introduction; References, entry 14)

The stated scientific basis also includes investigation of the influence of substrate mechanics on the properties of limbal cells.

Not verified in the article. The hypothesis cites a substrate-biomechanics study, but its experimental text is not supplied. The included migration models and extracellular-matrix observations do not verify that specific investigation of substrate mechanics and limbal cell properties.

Age-related loss of the ability of alveoli to restore their barrier after repeated small injuries may be transferred with the extracellular matrix after inflammation has been eliminated and the original cells have been removed.

Different experimental conditions. Decellularized older mouse matrix altered laminin expression in human lung cells; transfer of impaired alveolar barrier recovery after resolved inflammation and repeated injury was not tested.

Decreased Laminin Expression by Human Lung Epithelial Cells and Fibroblasts Cultured in Acellular Lung Scaffolds from Aged Mice (Results, Aged matrix regulates phenotype and ECM production in human lung epithelial and fibroblast cells; Figures 3-4.)

The competing explanation locates the age-related repair defect in the epithelial cells themselves.

Different experimental conditions. Crossing epithelial and stromal cell ages addressed epithelial versus niche contributions to alveolosphere formation, using living stromal cells and a different outcome.

Mesenchymal stromal cell aging impairs the self-organizing capacity of lung alveolar epithelial stem cells (Results and discussion; Figure 1H-J.)

The stated scientific rationale includes findings in mouse models that macrophage-derived interleukin-1β (IL-1β) promoted the transition of alveolar type II cells into an intermediate state, while prolonged inflammatory exposure prevented completion of their maturation.

Matches this study. Mouse experiments linked interstitial macrophage-derived IL-1β to intermediate epithelial states, while sustained IL-1β prevented terminal maturation and withdrawal restored maturation markers.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (Results, IL-1β Secreted from Interstitial Macrophages Triggers Reprogramming of AT2 Cells; Figures 2, 4 and 7.)

The stated scientific rationale includes convergence of different epithelial lineages into a Krt8+ transitional state after mouse lung injury and detection of similar cells in fibrotic human lung.

Matches this study. Lineage tracing supported airway and alveolar contributions to Krt8+ transitional cells after mouse injury; human fibrotic tissue contained related epithelial states.

Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis (Results, Transcriptional convergence of alveolar and airway stem cells; Figures 6-7 and 9.)

The stated scientific rationale includes findings in alveolar injury models that accumulation of intermediate epithelial cells induced a transitional fibroblast state and that elimination of transitional states also disrupted tissue architecture.

Not verified in the article. The supplied primary articles do not establish both induction of transitional fibroblasts by accumulated intermediate epithelial cells and architectural disruption following elimination of transitional states.

Lung matrices must be obtained from healthy young adult mice and naturally aged mice, and recipient epithelia must come from young or old animals.

Different experimental conditions. Matrices came from 4-6-month and 20-24-month mice, but recipients were human bone marrow mesenchymal stromal cells rather than young and old mouse epithelia.

Effects of aging on the biomechanical properties of the lung extracellular matrix: dependence on tissular stretch (Materials and methods, sections 2.1 and 2.5.)

Matrices must be obtained after an identical brief IL-1β pulse or exposure to control medium.

Different experimental conditions. IL-1β exposure and withdrawal were tested in living epithelial-stromal organoids, not as a brief treatment preceding isolation of young and aged lung matrices.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (Figure 7D-E; STAR Methods, Primary 3D Lung organoid co-culture.)

Following the pulse, IL-1β must be washed out and the original cells removed before the matrices are reseeded with epithelium.

Not verified in the article. IL-1β was withdrawn after 14 days, but original cells remained in the organoids; the combined washout, decellularization and reseeding sequence is absent.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (Results, Chronic Inflammation Mediated by Sustained IL-1β Levels Stalls Transition of DATPs into Mature AT1 Cells; Figure 7D-E.)

For both IL-1β and control-medium conditions, matrix age and epithelial age must be crossed in all four combinations: young matrix with young epithelium, young matrix with old epithelium, old matrix with young epithelium, and old matrix with old epithelium.

Different experimental conditions. All four stromal-cell-age-by-epithelial-age combinations were examined in Matrigel, but neither acellular matrix age nor IL-1β-versus-control pretreatment was crossed.

Mesenchymal stromal cell aging impairs the self-organizing capacity of lung alveolar epithelial stem cells (Figure 1H-J; Materials and methods, Cell culture.)

The number and composition of seeded epithelial cells must be equalized across experimental groups.

Matches this study. The age-crossing organoid assay used a fixed input of 5,000 purified type II epithelial cells and 100,000 stromal cells per well, with epithelial purity assessed.

Mesenchymal stromal cell aging impairs the self-organizing capacity of lung alveolar epithelial stem cells (Figure 1A,H; Materials and methods, Cell culture.)

Matrix preservation, absence of active IL-1β, and barrier tightness must each be checked separately before the second injury.

Not verified in the article. Matrix architecture, composition and cell removal were assessed, but separate checks for active IL-1β absence and barrier tightness before a second injury were not reported.

Decreased Laminin Expression by Human Lung Epithelial Cells and Fibroblasts Cultured in Acellular Lung Scaffolds from Aged Mice (Methods, qRT-PCR; Results, Age-related changes in matrix composition; Figures 1-2.)

The reseeded systems must receive an identical second microinjury.

Not verified in the article. No supplied study administered an identical second microinjury to the specified reseeded matrix-epithelium systems.

Only regions with equal initial leakage must be compared, and every exclusion must be recorded.

Not verified in the article. Selection of regions with equal initial leakage, together with recording every exclusion from that comparison, is not documented.

The primary outcome is the time required for albumin permeability to return to its individual pre-injury level after the second injury.

Not verified in the article. None of the supplied studies measured time for albumin permeability to return to the individual pre-injury baseline after the second injury.

Matrix donors and epithelial donors must define the independent experimental units, with matrix age and epithelial age crossed in the analysis.

Different experimental conditions. Mice were biological replicates and epithelial and stromal cell ages entered a two-factor analysis; independent matrix donors and epithelial donors were not the tested factors.

Mesenchymal stromal cell aging impairs the self-organizing capacity of lung alveolar epithelial stem cells (Materials and methods, Statistical analysis; Figure 1H-J; Author response, reviewer 2, point 3.)

The matrix-memory hypothesis predicts that old matrix after IL-1β will slow barrier recovery even in young epithelium.

Different experimental conditions. Aged living stromal cells impaired alveolosphere organization with young epithelium; old matrix after IL-1β slowing barrier recovery was not tested.

Mesenchymal stromal cell aging impairs the self-organizing capacity of lung alveolar epithelial stem cells (Results and discussion; Figure 1H-J.)

The matrix-memory hypothesis predicts that young matrix will accelerate barrier recovery in old epithelium, partially restoring its repair capacity.

Different experimental conditions. Young living stromal cells supported relatively normal alveolospheres with aged epithelium, but young acellular matrix accelerating barrier recovery was not examined.

Mesenchymal stromal cell aging impairs the self-organizing capacity of lung alveolar epithelial stem cells (Results and discussion; Figure 1H-J.)

The effect of matrix age on barrier recovery must be greater after the IL-1β pulse than under control-medium conditions.

Not verified in the article. The predicted interaction between matrix age and prior IL-1β exposure on barrier-recovery time was not tested.

If recovery rate changes only with epithelial cell age, the matrix mechanism is rejected.

Not verified in the article. No supplied study applied the specified rejection criterion based on barrier recovery depending exclusively on epithelial age.

The inference is limited to reversibility of one component of lung aging, namely loss of barrier reserve.

Not verified in the article. The supplied experiments do not establish reversibility specifically of age-related loss of barrier reserve.

If young and old systems do not differ in recovery after repeated injury, the experiment provides no basis for identifying the matrix as a target for age-related repair.

Not verified in the article. The decision rule withholding matrix targeting when young and old systems recover equally after repeated injury was not evaluated.

A positive result would support distinguishing age-related matrix damage from epithelial aging when selecting a target for restoring lung resilience.

Not verified in the article. Existing niche-aging results do not provide the proposed positive matrix-transfer result separating matrix damage from epithelial aging for barrier-resilience targeting.

If the hypothesis is refuted, this approach must not proceed to the next stage.

Not verified in the article. A stopping rule preventing progression of this matrix-transfer approach after refutation is not documented in the supplied studies.

Experimental conditions must be randomly assigned, and group codes must be concealed during measurements.

Matches this study. Mice were randomly assigned to treatment or control, and cell-counting observers were blinded to genotype and condition. This matches those safeguards for cell counts, not for the proposed barrier assay.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (STAR Methods, Quantification and Statistical Analysis.)

Before the main experiment, an independent pilot must establish reproducibility, the working time frame, and the minimum distinguishable and biologically meaningful effect.

Not verified in the article. Pilot experiments informed animal sample size, but an independent pilot establishing reproducibility, the working time frame and minimum distinguishable and biologically meaningful effect was not documented.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (STAR Methods, Quantification and Statistical Analysis.)

The contrast and its confidence interval must be estimated at the level of independent experimental units.

Not verified in the article. The specified barrier-recovery contrast and confidence interval at the independent matrix-and-epithelial-donor level were not reported.

The experiment cannot distinguish the competing explanations if the intervention fails to separate the groups or if the confidence interval permits substantial effects in both directions.

Not verified in the article. The proposed inconclusive-result rule for unsuccessful group separation or substantial effects of both signs within the confidence interval was not applied.

The hypothesis concerns DNA repair during cellular aging.

Different experimental conditions. Pfister and colleagues studied human cancer cell lines with experimental SETD2 or H3K36me3 perturbations, rather than a cellular-aging model.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results, Figures 1-5; Experimental Procedures.)

Reduced histone H3 lysine 36 trimethylation (H3K36me3) may locally limit accurate homologous repair in actively transcribed regions even when the global level of RAD51 is sufficient.

Matches this study. SETD2 depletion reduced H3K36me3, reporter homologous repair and local RAD51 recruitment while leaving total RAD51 protein unchanged. The reporter was driven by an active CMV promoter. This matches the mechanistic component, with aging addressed separately.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results, Figures 2B-2D and 3D; Discussion.)

Compare the same reporter in transcriptionally active and inactive states.

Not verified in the article. The supplied experiments do not compare the same reporter with transcription switched on and off. The yeast study compares breaks in different plasmid contexts.

Restore H3K36me3 locally using a catalytically active SETD2 domain.

Different experimental conditions. Inducible SETD2 expression restored H3K36me3 after endogenous SETD2 depletion. This was cellular complementation, without targeted local restoration by a SETD2 catalytic domain.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results, H3K36me3 Is Required for Homologous Recombination Repair; Figure 4 and Figure S4A.)

Compare the catalytically active SETD2 domain with an inactive variant.

Different experimental conditions. Wild-type and methyltransferase-dead SETD2 constructs were directly compared, establishing the catalytic-activity control. They were not the proposed locally targeted active and inactive domains.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results and Figure 4A-4D; Figures S4A-S4C.)

Measure transcription in the reporter experiment.

Matches this study. Spliced and unspliced HPRT transcripts were measured in the HPRT cleavage-reporter experiment and were unchanged after SETD2 depletion. This measurement was not part of a local-restoration experiment.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results, SETD2 Suppresses Break-Induced Mutations; Figures S1D and S1E.)

Measure initial cleavage in the reporter experiment.

Matches this study. I-SceI expression and cleavage efficiency were checked and found equivalent between control and SETD2-depleted reporter cells. Thus, the cleavage control has precedent, although the intervention differs.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results, SETD2 Suppresses Break-Induced Mutations; Figures S1A-S1C.)

Measure the level of H3K36me3 in the reporter experiment.

Matches this study. Chromatin immunoprecipitation measured H3K36me3 at the DR-GFP reporter near the induced break, including its loss after SETD2 depletion.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results, An Early Role for SETD2 in Homologous Recombination; Figure 3D and Figures S3A-S3C.)

The primary outcome is the frequency of error-free copying of a marked homologous template, which is expected to increase following local restoration of H3K36me3.

Different experimental conditions. The DR-GFP assay measured template-dependent restoration of a functional GFP gene, and wild-type SETD2 partially rescued repair. It did not test error-free marked-template copying after targeted local H3K36me3 restoration.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Figures 2C-2D and 4D; Results, H3K36me3 Is Required for Homologous Recombination Repair.)

Hold the proportion of cells in the S/G2 phases equal across the compared groups.

Different experimental conditions. Cell-cycle distributions were measured, with no detectable change after SETD2 depletion. This provides a related confounding control, but not the specified maintenance of equal S/G2 fractions across local-restoration and transcription-state groups.

SETD2 is required for DNA double-strand break repair and activation of the p53-mediated checkpoint (Results, Figure 5B; Materials and methods, Cell cycle analysis and survival assays.)

Local restoration of H3K36me3 is expected to improve repair predominantly in the S/G2 phases.

Not verified in the article. RAD51 recruitment in S/G2 and cell-cycle-dependent repair were studied, but no supplied experiment establishes that local H3K36me3 restoration improves accurate repair predominantly in S/G2.

An outcome explained by altered transcription would not demonstrate a local improvement in repair quality.

Matches this study. Unchanged HPRT transcription was used to support a repair-based interpretation of altered mutation frequency. This matches the transcription-confounding control as a component, but does not establish transcription independence of local restoration.

SETD2-Dependent Histone H3K36 Trimethylation Is Required for Homologous Recombination Repair and Genome Stability (Results, SETD2 Suppresses Break-Induced Mutations; Figures S1D and S1E.)

An outcome obtained at the cost of increased large rearrangements would not demonstrate a local improvement in repair quality.

Not verified in the article. The supplied studies do not evaluate increased large rearrangements as a disqualifying cost of local restoration. Sequencing small deletions at an HPRT break does not establish this control.

Polynucleotide kinase/phosphatase (PNKP) becomes limiting for neuronal DNA repair only at breaks with a chemically blocked end.

Not verified in the article. Purified-enzyme experiments establish end-dependent processing, and HeLa extracts show kinase-limited repair of blocked nicks. These results do not establish that PNKP limits neuronal repair exclusively at chemically blocked ends.

The phosphatase activity of mammalian polynucleotide kinase takes precedence over its kinase activity in repair of single strand breaks (Results and Discussion, Figures 2, 5 and 7.)

Age-related slowing of neuronal DNA repair may depend on the chemistry of the break end.

Not verified in the article. None of the supplied studies experimentally compares age-related slowing of neuronal repair across defined break-end chemistries.

The experiment uses neuronal extracts and includes testing in directly converted neurons from young and elderly donors.

Different experimental conditions. The study uses patient-derived fibroblasts, lymphoblastoid cells, cell extracts and recombinant proteins. These substitute for neuronal extracts and directly converted neurons from young and elderly donors.

Pathological mutations in PNKP trigger defects in DNA single-strand break repair but not DNA double-strand break repair (Materials and Methods, Cell lines and PNKP biochemical activity; Figures 1 and 4.)

Paired reporters with identical sequences but different break ends must be compared, with one end type carrying a 3′-phosphate and the other an ordinary 3′-OH.

Different experimental conditions. Nick1 and Nick2 use sequence-identical oligonucleotides differing in 3′-phosphate versus 3′-OH, so the paired-substrate chemistry is already represented. Their comparison concerns purified-enzyme processing, rather than the specified neuronal repair experiment.

The phosphatase activity of mammalian polynucleotide kinase takes precedence over its kinase activity in repair of single strand breaks (Figure 1; Results and Discussion, Figure 5A and the section on wild-type phosphatase preceding kinase activity.)

Introduce PNKP or a PNKP variant with its phosphatase activity disabled to test whether the proposed dependence on break-end chemistry requires PNKP phosphatase activity.

Different experimental conditions. Wild-type PNKP and phosphatase-inactive D171N were introduced into patient fibroblasts. Their effects were compared after irradiation or camptothecin, rather than across the paired neuronal reporters and donor age groups.

Pathological mutations in PNKP trigger defects in DNA single-strand break repair but not DNA double-strand break repair (Materials and Methods, Constructs, protein purification and transfection; Figure 4A-D.)

The primary outcome is the fraction of full-length ligated product for each end type, together with the interaction between end type and donor age group.

Not verified in the article. The study detects a full-length 40-nt ligation product in fibroblast extracts. It does not report the specified ligated-product fractions for paired end types together with an end-type-by-donor-age interaction.

Pathological mutations in PNKP trigger defects in DNA single-strand break repair but not DNA double-strand break repair (Figure 1C; Materials and Methods, PNKP biochemical activity.)

Restoring PNKP is predicted to improve repair more at 3′-phosphate ends than at ordinary 3′-OH ends.

Not verified in the article. The supplied studies do not measure whether restoring PNKP improves neuronal ligation more for 3′-phosphate than for sequence-identical 3′-OH substrates.

The proposed mechanism is rejected if the effect is independent of break-end chemistry or persists with the phosphatase-inactive PNKP variant.

Not verified in the article. Phosphatase-inactive PNKP failed to rescue irradiation-associated repair but rescued camptothecin-associated repair in fibroblasts. This qualifies the phosphatase-dependence component, but neither proposed rejection criterion was tested in the specified neuronal, age-stratified reporter experiment.

Pathological mutations in PNKP trigger defects in DNA single-strand break repair but not DNA double-strand break repair (Results, Requirement for the DNA 5′-kinase, DNA 3′-phosphatase, and FHA Domains of PNKP for SSBR; Figure 4B-D.)

The biological system is aging fibroblasts.

Different experimental conditions. The experiments use telomerase-expressing BJ human fibroblasts undergoing damage-induced premature senescence. They provide a related senescence model, but do not establish the proposed aging-fibroblast context with older donors.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Results, Figure 1; Methods, Cell culture and cell lines generation)

Accelerating the removal of 8-oxoguanine (8-oxoG) is proposed to be beneficial only when APE1 capacity is sufficient.

Not verified in the article. APE1 depletion partially rescues damage-induced senescence, implicating downstream strand-break formation. The study does not test whether sufficient APE1 capacity is necessary for accelerated 8-oxoG removal to improve final repair accuracy.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Results, BER intermediates promote telomeric 8oxoG-induced senescence; Supplementary Figure 4G-I as described in the main text)

Enhancing the glycosylase OGG1 during fibroblast aging may increase unfinished repair intermediates if the subsequent enzyme, APE1, acts slowly.

Different experimental conditions. OGG1-dependent telomeric strand-break intermediates and their contribution to senescence are demonstrated using glycosylase loss, inhibition, and PARP inhibition. OGG1 enhancement combined with slow APE1 activity during fibroblast aging is not tested.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Results, Figure 4A-F; Discussion)

Joint restoration of OGG1 and APE1 is predicted to reduce the risk of accumulating unfinished repair intermediates.

Not verified in the article. No supplied study tests whether joint OGG1 and APE1 restoration reduces unfinished repair intermediates in aging fibroblasts.

The experiment must compare four combinations of OGG1 and APE1 restoration.

Different experimental conditions. The four principal groups are wild type, OGG1 knockout, MUTYH knockout, and double knockout. Separate APE1 depletion experiments do not constitute four combinations of OGG1 and APE1 restoration.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Figure 1A-B; Methods, Cell culture and cell lines generation; siRNA transfections)

The compared experimental groups must receive the same oxidative pulse.

Matches this study. The compared fibroblast genotypes receive the same 20-minute dye-and-light exposure, with comparable targeting-protein expression checked. This matches the shared oxidative-pulse condition within a different intervention design.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Figure 1B; Results, OGG1 and MUTYH deficiency reduces sensitivity to acute oxidative telomere damage; Methods, Cell treatments)

The experiment must include catalytically inactive variants.

Not verified in the article. An inactive structural analog of the OGG1 inhibitor is included. This is a chemical control; catalytically inactive OGG1 or APE1 protein variants are not included in the proposed restoration comparison.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Results, Supplementary Figure 1D-E as described in the main text; Methods, Synthesis of OGG1i (TH5487) and OGG1i NA)

The experiment must measure initial 8-oxoG, abasic sites, breaks, and final mutations.

Not verified in the article. The study measures telomeric strand-break intermediates and, after chronic exposure, detects residual lesions using glycosylase-assisted analysis. It does not provide the complete joint measurement of initial 8-oxoG, abasic sites, breaks, and final mutations.

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced senescence in human fibroblasts (Figures 4A-C and 6E-G; Methods, Exo-FISH)

The primary outcome must be the fraction of fully repaired reporter molecules with a specified 8-oxoG lesion.

Different experimental conditions. Reporter plasmids contain a single site-specific 8-oxoG lesion, but the cellular outcome is reporter expression and transcriptional repression in HeLa cells. The fraction of fully repaired reporter molecules is not the measured outcome.

Widespread transcriptional gene inactivation initiated by a repair intermediate of 8-oxoguanine (Methods, Expression vectors and EGFP expression analyses by flow cytometry; Figures 1-2)

An additional outcome must be G→T substitutions per division in older donors.

Not verified in the article. No supplied study reports G→T substitutions per cell division in fibroblasts from older donors.

The proposed dependence on APE1 must be rejected if accelerated disappearance of 8-oxoG improves final repair accuracy equally at every APE1 level.

Not verified in the article. No supplied study compares the effect of accelerated 8-oxoG disappearance on final repair accuracy across APE1 levels using the specified rejection criterion.

The experiment uses chips made from small-intestinal organoids from elderly donors to model the aged intestinal barrier.

Different experimental conditions. The study used human colonic organoid-derived chips with endothelial cells. It did not establish the specified small-intestinal model from elderly donors.

A Novel Microphysiological Colon Platform to Decipher Mechanisms Driving Human Intestinal Permeability (Results: Development of a Colon Intestine-Chip Platform; Materials and Methods: Cell Culture)

IL-22 stimulates intestinal stem cells in injury models.

Matches this study. IL-22 treatment increased intestinal stem-cell recovery after transplantation-associated injury and supported survival or regeneration after irradiation in mouse experiments.

Interleukin-22 Promotes Intestinal Stem Cell-Mediated Epithelial Regeneration (Figure 3c-d; Extended Data Figure 5a-c; Extended Data Figure 10e-f)

Brief IL-22 delivery is predicted to restore intestinal barrier function only above a threshold residual number of viable crypts, even when individual cells have identical STAT3 response strength.

Not verified in the article. Depletion of Lgr5-positive cells abolished IL-22-mediated organoid growth. This establishes a related cellular requirement, but does not test a residual viable-crypt threshold for barrier restoration after brief treatment at identical single-cell STAT3 response strength.

Interleukin-22 Promotes Intestinal Stem Cell-Mediated Epithelial Regeneration (Figure 4d; Extended Data Figure 9a)

Micropatterning establishes three densities of independent crypts.

Not verified in the article. None of the supplied studies established three densities of independent crypts by micropatterning for this IL-22 experiment.

The initial defect area and total epithelial density are held identical across the three crypt densities.

Not verified in the article. The supplied studies do not verify equal initial defect area and total epithelial density across three experimentally imposed crypt densities.

Within each donor, the experiment compares IL-22, vehicle and blockade of the IL-22 receptor, IL-22R.

Different experimental conditions. The chip study compared IL-22 with vehicle and used IL-22-binding protein to neutralize the ligand. This differs from the specified within-donor IL-22R-blockade comparison in elderly small-intestinal chips.

A Novel Microphysiological Colon Platform to Decipher Mechanisms Driving Human Intestinal Permeability (Figure 8B, E-F; Materials and Methods: Cytokine Stimulation)

The dose is equalized, although the proposal does not specify which comparisons this equalization covers.

Not verified in the article. Studies report defined cytokine concentrations, but dose equalization within the proposed experiment is unverified. The proposal itself leaves unspecified which comparisons must have equal doses.

STAT3 activation is measured.

Matches this study. Flow cytometry measured IL-22-induced STAT3 Y705 phosphorylation in Lgr5-positive intestinal stem cells. Measuring activation does not establish equal response strength across crypt-density groups.

Interleukin-22 Promotes Intestinal Stem Cell-Mediated Epithelial Regeneration (Figure 4b-c; Methods: Flow cytometry)

The primary outcome is the fraction of the damaged surface covered by restored impermeable epithelium on day 7.

Different experimental conditions. The study measured dextran permeability during 72 hours of IL-22 exposure in an initially healthy colonic monolayer. It did not measure the fraction of a damaged surface restored to impermeable epithelium on day 7.

A Novel Microphysiological Colon Platform to Decipher Mechanisms Driving Human Intestinal Permeability (Figure 8F; Materials and Methods: Assessment of Apparent Permeability)

The crypt threshold is determined from a pilot series and fixed before validation.

Not verified in the article. No supplied study determined a viable-crypt threshold in a pilot series and fixed it before validation.

Equal functional benefit at all three crypt densities would refute the hypothesis.

Not verified in the article. Equal functional benefit across three crypt densities was not evaluated as a falsification criterion in the supplied studies.

Improvement attributable solely to a smaller initial wound area would refute the hypothesis.

Not verified in the article. The supplied studies do not test whether an apparent benefit is attributable solely to a smaller initial wound area, as required by the proposed falsification criterion.

The hypothesis concerns intestinal epithelial aging and is to be tested in organoids from several donors.

Different experimental conditions. The study examined small intestinal tissues in mice exposed to potassium bromate from four weeks of age. It did not test intestinal epithelial aging in organoids from several donors.

Oxidative stress accelerates intestinal tumorigenesis by enhancing 8-oxoguanine-mediated mutagenesis in MUTYH-deficient mice (Methods: Mice and KBrO3 administration; Figure 1)

The benefit of MUTYH is proposed to depend on the timing of the first division, with a greater reduction in error fixation during the first S-phase after oxidative stress than after the second division.

Not verified in the article. The supplied studies support MUTYH-mediated protection against oxidative mutagenesis, but do not compare its benefit during the first post-stress S-phase with its benefit after the second division.

Some substitutions are proposed to be already fixed after the second division, potentially limiting the benefit of MUTYH at that stage.

Not verified in the article. No supplied experiment tracks substitutions through the second division and tests whether their prior fixation limits the benefit of subsequently supplied MUTYH.

The experiment must use a reporter containing an 8-oxoG:A pair and labels on the original strands.

Different experimental conditions. The study used an integrated rpsL mutation reporter exposed to oxidative stress, rather than a reporter constructed with an 8-oxoG:A pair and labels identifying the original strands.

Oxidative stress accelerates intestinal tumorigenesis by enhancing 8-oxoguanine-mediated mutagenesis in MUTYH-deficient mice (Results: Analysis of somatic mutations in the normal precancer tissues by reporter gene assay; Methods: Mutation assay by rpsL-Tg mice)

MUTYH pulses before the first division must be compared with MUTYH pulses after the first division.

Not verified in the article. No supplied study compares MUTYH pulses delivered before versus after the first division.

The experimental comparisons must include an inactive enzyme and an undamaged reporter.

Not verified in the article. The required combination of an inactive MUTYH enzyme and an undamaged reporter is not documented. Untreated mice and catalytically inactive OGG1 used for structural analysis do not establish these controls.

The main outcome must measure the frequency of restoration of the original G:C pair and the frequency of G→T fixation in daughter molecules.

Different experimental conditions. The study quantified G:C > T:A mutations among recovered rpsL loci. It did not jointly measure restoration of the original G:C pair and G→T fixation in tracked daughter molecules.

Oxidative stress accelerates intestinal tumorigenesis by enhancing 8-oxoguanine-mediated mutagenesis in MUTYH-deficient mice (Results: Analysis of somatic mutations in the normal precancer tissues by reporter gene assay; Table 2; Figure 3)

The main outcome must be compared at the same number of divisions.

Not verified in the article. Cordero and colleagues describe a long-term assay over 100 generations, but no supplied study compares the proposed reporter outcomes between MUTYH pulse groups at the same division count.

The proposed timing constraint is unsupported if the effect depends only on total expression duration rather than division number.

Not verified in the article. No supplied study separates the effects of total MUTYH expression duration and division number to evaluate the proposed falsification criterion.

The hypothesis proposes that basolateral leakage of WNT2B determines whether regenerating tubular epithelium becomes profibrotic, because access of WNT2B to the stromal side promotes fibroblast collagen deposition even when total ligand production is equal.

Not verified in the article. The study connects FoxM1-regulated Wnt expression, including Wnt2b, with profibrotic responses, but does not establish directional stromal access at equal production or WNT2B-specific fibroblast collagen deposition.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Results 3.3-3.7; Figures 3-7)

The competing explanation attributes fibroblast activation exclusively to the amount of ligand synthesized.

Not verified in the article. Manipulating Wnt expression does not test whether ligand quantity exclusively determines fibroblast activation independently of access.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Results 3.3-3.7; Discussion)

The cited biological rationale describes epithelial cells switching off SOX9 after restoration of polarity following acute kidney injury in mice, whereas cells retaining SOX9 and CDH6 sent WNT signals to neighboring fibroblasts.

Not verified in the article. The supplied literature does not document the SOX9/CDH6 polarity-dependent epithelial states or their signaling to neighboring fibroblasts; the cited Aggarwal study is not supplied.

The biological rationale also reports similar cellular states in transplanted human kidneys.

Not verified in the article. Human biopsies show tubular FoxM1 expression in chronic kidney disease, but do not verify the specified cellular states in transplanted kidneys.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Methods 2.12; Results 3.1; Figure 1G)

The decisive experiment uses a two-chamber chip containing proximal tubular epithelium from elderly donors, with fibroblasts located outside the epithelium on the stromal side.

Different experimental conditions. The study uses young mice, rat NRK-52E epithelial cells, HEK 293T reporter cells and human biopsies, rather than an elderly-donor epithelial chip with stromal fibroblasts.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Methods 2.1, 2.2, 2.10 and 2.12)

The epithelial preparations undergo identical ischemia before the experimental interventions.

Different experimental conditions. Injury is induced by ureteral obstruction or folic acid in mice and angiotensin II in cultured cells, rather than identical ischemia of epithelial preparations.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Methods 2.1-2.2)

The experiment compares equal masses of active WNT2B delivered exclusively into the lumen or exclusively to the basal side.

Not verified in the article. No supplied experiment compares equal masses of active WNT2B delivered exclusively to luminal versus basal compartments.

The side-specific comparison is repeated with epithelial WNT2B suppression followed by WNT2B add-back to the luminal or basal side.

Different experimental conditions. The interventions suppress FoxM1 or β-catenin or inhibit FoxM1 with Siomycin A; they do not selectively suppress epithelial WNT2B and perform side-specific add-back.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Methods 2.7; Results 3.3-3.5; Figures 3-5)

WNT2B activity is measured on both sides using a bioreporter.

Different experimental conditions. Luciferase reporters measure Wnt promoter regulation in HEK 293T cells, rather than extracellular WNT2B activity on both sides of an epithelial barrier.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Methods 2.10; Results 3.6; Figure 6E)

Through-leakage between the two sides must be excluded to establish that the chip preserves separate luminal and basal compartments.

Not verified in the article. The supplied literature contains no test excluding leakage between luminal and basal chip compartments.

The primary outcome is the amount of newly deposited fibroblast collagen per unit area over seven days.

Different experimental conditions. The study measures fibrotic area and collagen I abundance in kidneys or epithelial cultures, rather than newly deposited fibroblast collagen per unit area over seven days.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Methods 2.3 and 2.5; Results 3.2-3.5; Figures 2-5)

Basal WNT2B add-back is predicted to restore collagen deposition more strongly than apical add-back under conditions of equal production and viability.

Not verified in the article. No supplied result compares basal and apical WNT2B rescue of collagen deposition at equal production and viability.

Exact equality of the outcomes between the two sides in a sealed chip would exclude a role for directional access under the tested conditions.

Not verified in the article. Exact equality between delivery sides in a sealed chip is neither tested nor reported as a result.

The independent experimental unit is the epithelial donor, with blocking by fibroblast donor.

Different experimental conditions. The experiments use mice and cultured-cell replicates, rather than epithelial donors as independent units with blocking by fibroblast donor.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Methods 2.1-2.2 and 2.13; Figures 1-7)

Assignment of experimental conditions is randomized.

Not verified in the article. Randomized assignment of experimental conditions is not documented in the supplied methods.

Group codes are concealed during outcome measurement.

Not verified in the article. Concealment of group codes during outcome measurement is not documented.

Before the main experiment, an independent pilot determines reproducibility, the working duration, and the minimum distinguishable and biologically meaningful effect.

Not verified in the article. No independent pilot establishing reproducibility, working duration and the minimum distinguishable and biologically meaningful effect is described.

The analysis estimates the contrast between conditions and its confidence interval at the level of independent experimental units.

Different experimental conditions. The study reports means with standard errors and one-way analysis of variance with Tukey comparisons, rather than the specified donor-level contrast and confidence interval.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Methods 2.13)

The experiment does not distinguish the explanations if the intervention fails to separate the groups or if the confidence interval allows substantial effects in both directions.

Not verified in the article. The supplied literature does not apply the specified inconclusive-result rule based on intervention separation and confidence intervals allowing substantial effects in both directions.

The conclusion is restricted to ligand availability; the two sides cannot be distinguished in an injured tubule that lacks an intact seal.

Not verified in the article. The supplied experiments do not establish a ligand-availability conclusion conditional on intact separation of luminal and stromal compartments.

A positive result would justify directing local WNT2B neutralization to the stromal side of the tubule.

Not verified in the article. Systemic FoxM1 inhibition supports a different therapeutic intervention; it does not test or justify stromal-side local WNT2B neutralization through the proposed directional experiment.

FoxM1 promotes Wnt/β-catenin pathway activation and renal fibrosis via transcriptionally regulating multi-Wnts expressions (Methods 2.1; Results 3.2 and 3.7; Discussion)

If the hypothesis is refuted, the proposed stromal-side local neutralization approach does not advance to the next stage.

Not verified in the article. No supplied study implements the decision to stop stromal-side neutralization development after refutation of the directional-access hypothesis.

The experiment uses chips containing labeled alveolar type 2 (AT2) cells from elderly donors to study maturation in aged epithelium.

Different experimental conditions. Patient-derived AT2 cells were expanded as organoids and their mixed epithelial progeny cultured on chips. Elderly donor selection and persistent AT2 lineage labeling were not established; magnetic labeling for isolation does not provide descendant tracking.

A novel alveoli-on-chip platform for modeling cyclic stretch in patient-derived alveolar epithelial cells cultured from organoids (Methods 2.4-2.7 and 2.12; Results 3.5, Figure 5A.)

The mechanical forces of breathing are proposed to maintain the identity of mature alveolar type 1 (AT1) cells.

Not verified in the article. The article cites the study on respiration maintaining alveolar cell fate, but that study's methods and results are not supplied. The chip experiment measures transcriptional responses in mixed epithelial populations rather than directly testing maintenance of mature AT1 identity.

A novel alveoli-on-chip platform for modeling cyclic stretch in patient-derived alveolar epithelial cells cultured from organoids (Introduction; Discussion; References, Shiraishi et al., Cell 2023.)

Restoring physiological cyclic stretch after transitional cells appear is predicted to improve their maturation and help them complete the alveolar barrier under matched inflammatory conditions.

Different experimental conditions. Maturation of stalled transitional cells was rescued by IL-1β withdrawal or by 2-deoxyglucose during continued IL-1β exposure in mouse organoids. Physiological stretch restoration and resulting barrier completion in elderly donor chips were not tested.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (Results, Chronic Inflammation Mediated by Sustained IL-1β Levels Stalls Transition of DATPs into Mature AT1 Cells; Figure 7D-H.)

The experiment compares cyclic stretch during early and late periods with static stretch at the same mean deformation.

Different experimental conditions. Engineered rat lung tissues received cyclic or tonic 2.5% strain during days 7-10, with unstretched controls. There was no early-versus-late intervention comparison, and matching the mean deformation of cyclic and tonic conditions was not documented.

Rational engineering of lung alveolar epithelium (Results, Tidal strain synergizes with Wnt/FGF withdrawal to promote the AEC1 fate; Figure 7A-B; Methods, Engineered lung (slice) tissue culture.)

Stretch pulse durations must be equal.

Not verified in the article. No supplied experiment documents equal stretch pulse durations in the proposed early and late intervention groups. Equal total culture or exposure periods do not establish this requirement.

Oxygen supply, interleukin-1β (IL-1β) supply and the flow regimen must be identical across the compared conditions.

Not verified in the article. No supplied stretch experiment verifies the combined requirement of identical oxygen supply, IL-1β supply and flow regimen across the proposed comparison groups.

AT1 descendants of the labeled AT2 cells and membrane damage must be tracked.

Not verified in the article. Mouse lineage tracing establishes AT2-derived transitional cells and AT1 descendants. Combined tracking of these descendants and membrane damage during the proposed stretch experiment in elderly donor chips is absent.

Inflammatory Signals Induce AT2 Cell-Derived Damage-Associated Transient Progenitors that Mediate Alveolar Regeneration (Results, Figures 1, 3 and 4; Methods, Mouse Models and lineage tracing.)

The primary outcome is labeled albumin leakage on day 14 after wounding, with reduced leakage expected following restoration of physiological cyclic stretch after transitional cells appear.

Different experimental conditions. Permeability was measured on culture day 5 using fluorescein and 70 kDa dextran after stretching during days 2-5, and it increased. This differs from labeled albumin leakage on day 14 after wounding following stretch restoration after transitional-cell emergence.

Medium throughput breathing human primary cell alveolus-on-chip model (Methods, Permeability assay; Results and Discussion, Figure 6A-C.)

An increase in the number of AGER-positive cells without a reduction in albumin leakage does not support the prediction.

Not verified in the article. No supplied study applies the specified joint criterion that increased AGER-positive cell numbers must accompany reduced albumin leakage to support the prediction.

If the difference disappears when cell death is equalized, that difference does not establish a role for maturation.

Different experimental conditions. The rat monolayer study measured viability and found that kinase inhibitors altered permeability without changing stretch-associated cell death. It did not equalize cell death between the proposed stretch-timing groups to determine whether a maturation effect persisted.

MAPk Activation Modulates Permeability of Isolated Rat Alveolar Epithelial Cell Monolayers Following Cyclic Stretch (Methods, Cell Viability Measurement; Results, inhibitor toxicity assessment and Figure 4; Discussion.)

The availability of the daughter-strand signal is proposed to limit the accuracy of mismatch repair (MMR) after a replication pause.

Different experimental conditions. Yeast experiments linked the repair window to replication-associated nick lifetime by delaying Pms1 expression and Cdc9 activity. They tested temporal uncoupling of repair from replication, rather than correct strand choice after a replication pause.

Ligation of newly replicated DNA controls the timing of DNA mismatch repair (Results and Discussion; Figure 4)

In aging proliferating cells, a short delay between a copying error and its detection may reduce the ability to repair the daughter strand specifically.

Not verified in the article. The supplied studies do not test whether a short delay in mismatch detection reduces daughter-strand-specific repair in aging proliferating cells.

The daughter-strand signal is proposed to depend on time, with premature closure of the nearest nick expected to strengthen the dependence of correct strand choice on timing.

Different experimental conditions. Cdc9 overexpression increased mutation rates, whereas reduced or delayed ligase activity extended the repair window in yeast. This establishes a close mechanistic component, but does not directly test how premature closure of the nearest defined nick changes the timing dependence of correct strand choice.

Ligation of newly replicated DNA controls the timing of DNA mismatch repair (Results and Discussion; Figures 1 and 4)

The experiment is to be performed in intestinal organoid extracts.

Different experimental conditions. The closest biochemical timing experiments used Xenopus egg extracts. Intestinal organoid extracts were not used in any supplied study.

MutSα maintains the mismatch repair capability by inhibiting PCNA unloading (Results; Materials and methods, Xenopus egg extracts)

The reporter must contain one specified mismatch and a nick only in the daughter strand, with experimentally controlled ligation timing.

Different experimental conditions. The study used a defined A:C mismatch with a strand-specific gap or nick and sealed nicks with T4 DNA ligase after PCNA loading. Its timing assays primarily used gap filling or preligated substrates; they did not vary ligation timing on the specified daughter-strand-only nick reporter.

MutSα maintains the mismatch repair capability by inhibiting PCNA unloading (Figures 1-4; Materials and methods, Preparation of the MMR substrates and In vitro PCNA-loading assay)

Early and late substrate presentation must be compared.

Different experimental conditions. Stepwise incubations compared different delays before adding fresh extract to restore missing repair factors. This closely addresses delayed repair initiation, but substitutes factor restoration for the proposed early versus late substrate presentation.

MutSα maintains the mismatch repair capability by inhibiting PCNA unloading (Figures 2, 6, 7 and 9)

The experiment must test whether the observed effect depends on the MSH2-MSH6 complex.

Matches this study. Depletion and recombinant Msh2-Msh6 add-back experiments directly tested MutSα-dependent retention of strand information, including wild-type and interaction-defective complexes. This control is established as a component in Xenopus extracts.

MutSα maintains the mismatch repair capability by inhibiting PCNA unloading (Figures 8 and 9; Figure 8 supplement 1)

The primary outcome is the fraction of corrections in the correct strand, measured separately from the total number of mismatches that disappear.

Different experimental conditions. Restriction assays separately quantified A-to-G and C-to-T repair products, establishing strand-resolved measurements. The reported endpoints were repair yields relative to substrate, rather than the specified correct-strand correction fraction separately evaluated alongside total mismatch disappearance in a ligation-timing experiment.

MutSα maintains the mismatch repair capability by inhibiting PCNA unloading (Figure 1C-F; Figures 4 and 7; Materials and methods, MMR and gap-filling assays in NPE)

If correct strand choice does not depend on ligation timing when repair enzymes are intact, the temporal-signal hypothesis is not supported.

Not verified in the article. No supplied study applies the specified falsification test: varying ligation timing with intact repair enzymes and determining whether correct strand choice remains unchanged in intestinal organoid extracts.