Three-dimensional87Rb NMR imaging and spectroscopy of K+ fluxes in normal and postischemic pig hearts
Bibliographic record
Abstract
K(+) uptake rates were measured in the anterior (An) and posterior (Pos) LV walls of pig hearts before and after regional ischemia and reperfusion using Rb(+) as a K(+) congener and 3D (87)Rb NMR imaging and spectroscopy as detection methods. The hearts were perfused by the Langendorff method with Krebs-Henseleit (KH) buffer and loaded with Rb(+) (4.7 mM, Rb-KH) after 120-min ischemia and 60-min reperfusion. A second protocol involved Rb(+) loading prior to ischemia. Ischemia was produced by occlusion of the left anterior descending artery, which after 110 min of reperfusion resulted in infarction in the An wall (24 +/- 6% of the LV mass) determined by triphenyltetrazolium chloride staining. At the end of reperfusion pressure-rate product and oxygen consumption rate decreased to 58 +/- 10 and 74 +/- 4% of their preischemic values, respectively. Phosphocreatine, ATP, and intracellular pH (pHi), measured by (31)P NMR spectroscopy in the infarcted area, decreased to 59 +/- 17, 32 +/- 6%, and 6.7 +/- 0.36 (from 7.05 +/- 0.13), respectively. Serial (87)Rb images were acquired according to both protocols. Rate constants (k x 10(3), min(-1)), relative amount of intracellular Rb(+) (A, %) and relative fluxes (F = kA, %/min) for the An and Pos walls were determined from the images. Before ischemia, F and k were comparable in the Pos and An walls. Ischemia + reperfusion decreased F in the An wall (from 4.4 +/- 0.3 to 1.4 +/- 0.85) due to a decrease in A (20 vs. 73) and increased F in Pos wall (from 3.2 +/- 0.6 to 6.6 +/- 0.23) due to an increase in k (from 42 +/- 3 to 93 +/- 6). The intensities of the Rb images correlated with the Rb(+) content measured in tissue samples. Magn Reson Med 44:83-91, 2000. Published 2000 Wiley-Liss, Inc.
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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 | 0.001 | 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".