Caloric restriction attenuates apoptosis in larger type II fibers with aging
Bibliographic record
Abstract
Apoptosis has been implicated in the age‐related decline in skeletal muscle mass known as sarcopenia. Similarly, an attenuation of apoptosis is thought to contribute to the attenuation of sarcopenia by caloric restriction (CR). On this basis, we examined markers of apoptotic activation in cross‐sections of gastrocnemius muscle (Gas) from young adult (YA) and senescent (SEN) ad libitum fed (AL) and CR rats. Although CR markedly attenuated Gas atrophy (27% vs 51% for CR vs AL) and fiber atrophy (26% vs 40% in CR vs AL) with aging, CR did not affect the proportion of nuclei that were TUNEL positive (1.9±0.2% vs 3.0±0.2% for AL vs CR, respectively). Similarly, the number of TUNEL positive nuclei per 100 fibers was not different in SEN CR (11.0±1.1) vs SEN AL (8.3±0.8). On a fiber type basis, type IIa (58%) and IIb/x (51%) fibers exhibited more atrophy with aging in AL than type I fibers (31%), whereas fiber atrophy was less severe and more uniform among fiber types in CR (21%, 11% and 25% for type I, IIa and IIb/x, respectively). Interestingly, whereas fibers with TUNEL positive nuclei were larger than the mean for both type IIa and IIb/x in SEN AL, this was not the case for CR. Collectively, these results suggest that the apoptosis of nuclei in larger type II fibers of AL may contribute to their greater atrophy with aging and that this process may be attenuated by CR.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".