Cigarette smoke exposure induces diaphragm atrophy that partially regresses following cessation
Bibliographic record
Abstract
Atrophy is well known to occur in the diaphragm and limb muscles of patients with chronic obstructive pulmonary disease (COPD), a disease predominantly caused by cigarette smoke exposure. Interestingly, non‐COPD smokers also exhibit limb muscle atrophy; a finding that implicates cigarette smoke as a cause of atrophy. This has been substantiated in animal models demonstrating that limb muscle atrophy occurs early following cigarette smoke exposure and prior to overt lung dysfunction. These studies also indicate that pro‐atrophy pathways are partially reversed upon the cessation of cigarette smoke exposure suggesting possible regression of atrophy. However, the effect of cigarette smoke exposure and cessation, on diaphragm muscle atrophy, has not been investigated. Thus, the overall objective of this project is to investigate the effect of cigarette smoke exposure on the development of diaphragm atrophy in mice. We hypothesize that cigarette smoke exposure in mice will induce diaphragm atrophy; further, will be reversed following cessation. Methods BALB/c mice were repeatedly exposed to room air or cigarette smoke twice a day, 5 days/week. To assess the pathological development of diaphragm atrophy, mice were exposed to either 8 or 24 weeks of cigarette smoke. Following initial exposure, a subset of mice were switched to room air for an additional 8 weeks to evaluate the effect of cigarette smoke cessation. All groups were compared to non‐smoking controls. At the time of sacrifice, mice were formalin fixed and diaphragm tissue was removed for histological evaluation of diaphragm myocyte cross sectional area (CSA). Results In comparison to non‐smoking controls, diaphragm CSA was reduced by 40% following 8 weeks cigarette smoke exposure and did not worsen by 24 weeks. Median diaphragm CSA in 8 and 24 week exposure groups were 220um 2 and 215um 2 respectively, which was significantly reduced from 370um 2 in non‐smoking controls (p<0.05). In mice switched to room air, diaphragm CSA was reduced by 20% as compared to non‐smoking controls; 298um 2 vs. 370um 2 respectively. Conclusions Here we demonstrate that diaphragm atrophy is induced early following cigarette smoke exposure and does not worsen with prolonged experience. Further, our data indicate that the cessation of cigarette smoke exposure partially regresses diaphragm atrophy. In future work we aim to identify the intracellular mechanisms through which diaphragm atrophy develops in response to cigarette smoke exposure. Support or Funding Information Canadian Thoracic Society/ Canadian Lung Association
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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 | 0.001 |
| 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".