Effects of Exposure to Intermittent Hypoxia on Oxidative Stress and Acute Hypoxic Ventilatory Response in Humans
Bibliographic record
Abstract
RATIONALE: Periodic occlusion of the upper airway in patients with obstructive sleep apnea leads to chronic intermittent hypoxia, which increases the acute hypoxic ventilatory response (AHVR). Animal studies suggest that oxidative stress may modulate AHVR by increasing carotid body sensitivity to hypoxia. This has not been shown in humans. OBJECTIVES: To determine whether 4 days of exposure to chronic intermittent hypoxia increases AHVR and oxidative stress and to determine the strength of the association between oxidative stress and AHVR. METHODS: After two normoxic control days (Day -4 and Day 0), 10 young healthy men were exposed awake to 4 days (Days 1-4) of intermittent hypoxia for 6 hours per day. MEASUREMENTS AND MAIN RESULTS: AHVR, assessed using an isocapnic hypoxia protocol, was determined as the slope of the linear regression between ventilation and oxygen desaturation. Oxidative stress was evaluated by measuring plasma DNA, lipid and protein oxidation, uric acid and antioxidant status by measuring alpha-tocopherol, total vitamin C, and antioxidant enzymatic activities. Between baseline and Day 4, there were significant increases in AHVR, DNA oxidation, uric acid, and vitamin C, whereas antioxidant enzymatic activities and alpha-tocopherol were unchanged. There were strong correlations between the changes in AHVR and DNA oxidation (r = 0.88; P = 0.002). CONCLUSIONS: Chronic intermittent hypoxia increases oxidative stress by increasing production of reactive oxygen species without a compensatory increase in antioxidant activity. This human study shows that reactive oxygen species overproduction modulates increased AHVR. These mechanisms may be responsible for increased AHVR in patients with obstructive sleep apnea.
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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".