MAPK signaling in the quadriceps of patients with chronic obstructive pulmonary disease
Bibliographic record
Abstract
Muscle atrophy in chronic obstructive pulmonary disease (COPD) is associated with reduced exercise tolerance, muscle strength, and survival. The molecular mechanisms leading to muscle atrophy in COPD remain elusive. The mitogen-activated protein kinases (MAPKs) such as p38 MAPK and ERK 1/2 can increase levels of MAFbx/Atrogin and MuRF1, which are specifically involved in muscle protein degradation and atrophy. Our aim was to investigate the level of activation of p38 MAPK, ERK 1/2, and JNK in the quadriceps of patients with COPD. A biopsy of the quadriceps was obtained in 18 patients with COPD as well as in 9 healthy controls. We evaluated the phosphorylated as well as total protein levels of p38 MAPK, ERK 1/2, and JNK as well as MAFbx/Atrogin and MuRF1 in these muscle samples. The corresponding mRNA expression was also assessed by RT-PCR. Ratios of phosphorylated to total level of p38 MAPK (P = 0.02) and ERK 1/2 (P = 0.01) were significantly elevated in patients with COPD compared with controls. Moreover, protein levels of MAFbx/Atrogin showed a tendency to be greater in patients with COPD (P = 0.08). mRNA expression of p38 MAPK (P = 0.03), ERK 1/2 (P = 0.02), and MAFbx/Atrogin (P = 0.04) were significantly elevated in patients with COPD. In addition, phosphorylated-to-total p38 MAPK ratio (Pearson's r = -0.45; P < 0.05) and phosphorylated-to-total ERK 1/2 ratio (Pearson's r = -0.47; P < 0.05) were negatively associated with the mid-thigh muscle cross-sectional area. These data support the hypothesis that the MAPKs might play a role in the development of muscle atrophy in COPD.
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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".