CARDIAC FUNCTION, MYOCARDIAL GLUTATHIONE, AND MATRIX METALLOPROTEINASE-2 LEVELS IN HYPOXIC NEWBORN PIGS REOXYGENATED BY 21%, 50%, OR 100% OXYGEN
Bibliographic record
Abstract
After asphyxia, it is standard to resuscitate the newborn with 100% oxygen, which may create a hypoxia-reoxygenation process that may contribute to subsequent myocardial dysfunction. We examined the effects of graded reoxygenation on cardiac function, myocardial glutathione levels, and matrix metalloproteinase (MMP)-2 activity during recovery. Thirty-two piglets (1-3 days old, weighing 1.5-2.1 kg) were anesthetized and instrumented for continuous monitoring of cardiac index, and systemic and pulmonary arterial pressures. After 2 h of hypoxia, piglets were randomized to receive reoxygenation for 1 h with 21%, 50%, or 100% oxygen (n = 8 each), followed by 3 h at 21% oxygen. At 2 h of hypoxemia (PaO2 32-34 mmHg), the animals had hypotension, decreased cardiac index, and elevated pulmonary arterial pressure (P < 0.001 vs. controls). Upon reoxygenation, cardiac function recovered in all groups with higher cardiac index and lower systemic vascular resistance in the 21% group at 30 min of reoxygenation (P < 0.05 vs. controls). Pulmonary artery pressure normalized in an oxygen-dependent fashion (100% = 50% > 21%), despite an immediate recovery of pulmonary vascular resistance in all groups. The hypoxia-reoxygenated (21%-100%) hearts had similarly increased MMP-2 activity and decreased glutathione levels (P < 0.05, 100% vs. controls), which correlated significantly with cardiac index and stroke volume during reoxygenation, and similar features of early myocardial necrosis. In neonatal resuscitation, if used with caution because of a slower resolution of pulmonary hypertension, 21% reoxygenation results in similar cardiac function and early myocardial injury as 50% or 100%. The significance of higher oxidative stress with high oxygen concentration is unknown, at least in the acute recovery period.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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".