The Effects of Oxygen-Derived Free-Radical Scavengers During Normothermic Ex-Situ Heart Perfusion
Bibliographic record
Abstract
Oxidative stress occurs during ex-situ heart perfusion (ESHP) and may negatively affect functional preservation of the heart. We sought to assess the status of key antioxidant enzymes during ESHP, and the effects of augmenting these antioxidants on the attenuation of oxidative stress and improvement of myocardial and endothelial preservation in ESHP. Porcine hearts were perfused for 6 hours with oxygen-derived free-radical scavengers polyethylene glycol (PEG)-catalase or PEG-superoxide dismutase (SOD) or with naive perfusate (control). The oxidative stress-related modifications were determined in the myocardium and coronary vasculature, and contractile function, injury, and endothelial integrity were compared between the groups. The activity of key antioxidant enzymes decreased and adding catalase and SOD restored the enzyme activity. Cardiac function and endothelial integrity were preserved better with restored catalase activity. Catalase and SOD both decreased myocardial injury and catalase reduced ROS production and oxidative modification of proteins in the myocardium and coronary vasculature. The activity of antioxidant enzymes decrease in ESHP. Catalase may improve the preservation of cardiac function and endothelial integrity during ESHP. While catalase and SOD may both exert cardioprotective effects, unbalanced SOD and catalase activity may paradoxically increase the production of reactive species during ESHP.
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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 | 0.001 |
| 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".