Phosphorylation status of matrix metalloproteinase 2 in myocardial ischaemia–reperfusion injury
Bibliographic record
Abstract
OBJECTIVE: To investigate whether alterations in the phosphorylation status of matrix metalloproteinase 2 (MMP-2) in the heart may be protective in the setting of ischaemia-reperfusion (IR) injury. DESIGN: In-vitro heart function and biochemical research study. SETTING: University basic science laboratory. INTERVENTIONS: Male Sprague-Dawley rats, weighing 250-350 g. Isolated rat hearts were perfused at constant pressure either aerobically for 75 min or subjected to 20 min of global, no-flow ischaemia followed by 30 min of reperfusion. MAIN OUTCOME MEASURES: Heart mechanical function, MMP-2 activity and troponin I levels. RESULTS: The serine/threonine phosphatase inhibitor okadaic acid (OA) improved the recovery of mechanical function compared with control IR hearts and prevented the loss of troponin I. OA significantly reduced protein phosphatase 2A, but not protein phosphatase 1, activity in perfused hearts. IR stimulated the activation and release of MMP-2 into the coronary effluent in the first 2 min of reperfusion. This was accompanied by a decrease in the remaining activity and protein level of MMP-2 in heart tissue determined at the end of the reperfusion. OA did not alter the IR-stimulated release of MMP-2 into the coronary effluent, but reduced the decrease in MMP-2 in reperfused hearts. The immunoprecipitation of heart homogenates using anti-phosphoserine antibody showed that MMP-2 is phosphorylated. The dephosphorylation of MMP-2 by alkaline phosphatase treatment of homogenates prepared from IR hearts treated with OA significantly increased MMP-2 activity. CONCLUSIONS: These results suggest that the phosphorylation status of MMP-2 is important in its contribution to myocardial IR injury.
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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) | 0.001 | 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".