Evaluation of whole muscle apoptotic susceptibility in young and old animals
Bibliographic record
Abstract
Apoptosis regulates muscle mass during disease and aging. However, the signaling pathways leading to apoptosis need to be established. We developed an in vitro muscle incubation and fractionation protocol to assess the activation and localization of apoptotic proteins in response to various stimuli. Soleus strips (∼10–15mg) from young (6 mo) and old (36 mo) F344XBN rats were used. These strips contain ∼30 fibers/mg weight with <1% fiber damage and they can be incubated in vitro for 4–6 hrs to assess their responsiveness to apoptotic agents. Following incubation, the strips were fractionated into mitochondrial and cytosolic fractions. Subsequently, indices of apoptotic susceptibility were measured. Incubation of muscle strips in vitro with the apoptosis‐inducing agent camptothecin for 4 hours resulted in an increase in mitochondrial Bax in both young and old animals. JNK phosphorylation and DNA fragmentation were elevated by 3‐fold in old, compared to young animals. Bax localization to mitochondria was increased by ∼40% in old animals, and there was a 30% increase in AIF localized to the cytosol. Surprisingly, we detected no differential localization of Cyto c to the cytosol between young and old animals. We conclude that this in vitro muscle strip protocol is useful for the assessment of apoptotic susceptibility in whole muscle.
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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 | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".