Studying ischemic preconditioning in isolated cardiomyocyte models
Bibliographic record
Abstract
Isolated cardiomyocytes, obtained by enzymatic digestion of whole hearts, have multiple advantages, most related to their accessibility to microscopic visualization, beyond the obvious elimination of other cell types that exist in the heart. Conversely, they cannot reproduce the mechanical disruption of reperfusion hypercontracture or the vascular phenomena of leukocyte plugging and compression from interstitial edema and contracture that can lead to the no-reflow phenomenon. Nevertheless, ischemic preconditioning has been consistently demonstrated to be a potent protective mechanism in freshly isolated and cultured cardiomyocytes across multiple species, indicating that much of the innate protection of ischemic preconditioning resides in cardiomyocytes. Centrifuging freshly isolated cardiomyocytes into a pellet with only a thin layer of supernatant covered by oil has proven to be an excellent model of simulated ischemia. In culture, cardiomyocytes may be exposed to severe hypoxia only or to various protocols for simulated ischemia in which an acid/lactate-rich, hyperkalemic extracellular environment with substrate deprivation (lacking glucose) is typically added. Reperfusion is simulated by well-oxygenated media of normal ionic composition. Cardiomyocyte injury has been usually evaluated by cell membrane permeability to dyes, often under hypo-osmotic conditions (osmotic fragility) or enzyme release. A survey of the use of cardiomyocyte models to study preconditioning is presented with the emphasis on examples of the innovative measurements, increasingly involving molecular techniques, that point to an increasing future role for these models in preconditioning research and, more generally, in the mechanistic study of myocardial ischemia/reperfusion.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
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".