Oxidative stress and mitochondrial dysfunction in human skeletal muscle: interaction of aging and physical activity
Bibliographic record
Abstract
Aging is associated with an increase in oxidative stress‐mediated toxicity and mitochondrial dysfunction. The objectives of this study were to investigate the molecular imprint of aging on mitochondrial dysfunction and oxidative damage, and their relationship to physical activity (PA). To do this, we measured the protein content of vastus lateralis citrate synthase (CS), electron transport chain (COX subunit –II and –IV), antioxidant enzymes (Mn‐SOD and Cu/Zn‐SOD) and DNA repair enzymes (mitochondrial and nuclear OGG1), as well as CS and complex IV enzyme activity in physically active young (mean ± SD: 22 ± 2 y, n = 11) and old (AO, 70 ± 5 y, n = 10) and frail old (FO, 65 ± 10 y, n = 12) subjects. The FO subjects were patients with osteoarthritis undergoing total joint arthroplasty. The FO group had significantly lower CS and COX‐IV protein content vs. both the young (CS, P = 0.002; COX‐IV, P = 0.003) and AO (CS, P = 0.008; COX‐IV, P = 0.02) groups. COX‐II content was lower in the FO vs. the young group only (P = 0.01). Complex IV activity was lower in the FO vs. both the young (P = 0.005) and AO (P = 0.01) groups. CS activity and Mn‐SOD protein content were lower in both older groups (AO: CS activity, P = 0.05 and Mn‐SOD, P = 0.0006; FO: CS activity, P = 0.0001 and Mn‐SOD, P = 0.0001) vs. the young group. Mitochondrial OGG1 was higher in the FO vs. both the young (P=0.03) and AO (P = 0.02) groups. There was no difference in nuclear OGG1 and Cu/Zn‐SOD protein content between the three groups. These findings imply that the lower mitochondrial capacity of FO adults may be associated with lower antioxidant enzyme protection, and that PA can attenuate age‐induced mitochondrial dysregulation in the elderly population. (Funded by NSERC Canada)
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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".