Autophagy And Apoptosis During Consecutive Moderate-intensity Workdays In The Heat In Young And Older Males
Bibliographic record
Abstract
Older males have a reduced capacity to dissipate heat relative to their younger counterparts, which is exacerbated following consecutive days of work. However, we showed this does not translate to altered physiological strain or work tolerance with similar durations of continuous work performed safely (i.e., core temperature ≤ 38 °C). Contrarily, the cellular process of autophagy, which is critical in preventing heat-induced cellular damage, is impaired with aging. Whether age-related autophagic impairments contribute to greater heat-induced cellular vulnerability, that may be exacerbated over consecutive workdays in the heat, remain unknown. PURPOSE: Evaluate the effect of prolonged moderate-intensity work performed in the heat over consecutive days on cellular stress in young and older males. METHODS: Nine young (mean [SD]: 22 [2] years) and 9 older (62 [5] years) males performed 240 min of moderate-intensity treadmill walking (metabolic heat production of ~200 W/m2) in a wet bulb globe temperature of 26 °C. Work was continuous until rectal temperature reached 38 °C, at which point work-rest allocations of 3:1 (15-min rest and 45-min work) were implemented. This work bout was repeated in the afternoon (following a 1 h lunch break) and the next morning. Proteins associated with autophagy (LC3-II) and apoptosis (caspase-3) were assessed via Western blot from peripheral blood mononuclear cells before and after each work bout. Data are reported as relative quantity (RQ) from baseline and analyzed via a two-way ANOVA, with Bonferroni correction (α = 0.05). RESULTS: Autophagic activity (LC3-II) was elevated in young males following day-long work as evidenced by an increase in LC3-II (1.86 RQ [0.79], p < 0.001), which was significantly higher than the first work bout (1.19 RQ [0.55], p = 0.006) and the second-day work bout (1.32 RQ [0.28], p = 0.041). In older males, LC3-II was unchanged (all p ≥ 0.999). However, caspase-3 was significantly higher in response to heated exercise across groups (time main effect, p = 0.002). CONCLUSIONS: We showed elevated autophagy in young males on the initial workday, but not during successive workdays, nor in older males. When combined with excess apoptotic responses, precautions may be necessary when consecutive workdays are performed in hot conditions, particularly in older males. Supported by: Workplace Safety Insurance Board (Ontario)
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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".