The rapid decline of MTT reduction is not a marker of death signaling in ouabain-treated cells.
Bibliographic record
Abstract
Decreased staining with dimethylthiazol diphenyltetrazolium (MTT) is widely used for cell death detection. This study examined MTT assay as a marker of the Na+i,K+i-independent mode of cell death revealed in ouabain-treated C7-MDCK cells derived from distal tubule of the Madin-Darby canine kidney. The action of 3-M ouabain on MTT reduction in C7-MDCK cells exhibited bipartite kinetics with a rapid ~2-fold decline occurring in 30-120 min and a delayed ~8-10-fold decrease after 10 hr of ouabain addition. Treatment with ouabain for 18 hr led to 6-fold activation of caspase-3, 4-fold elevation of chromatin fragmentation, and massive cell detachment. Caspase-3 activation, chromatin fragmentation and cell detachment were completely abolished by acidification of the incubation medium from pH 7.2 to 6.7. In contrast, the 2-fold inhibition of MTT reduction seen in 5 hr of ouabain addition was not affected by medium acidification. Within the 5-hr time window, we did not observe any significant impact of ouabain on the cellular redox state estimated by the autofluorescence ratio of reduced pyridine nucleotides and oxidized flavoproteins. In rat aortic endothelial cells and primary astrocytes, exposure to 5-mM ouabain attenuated MTT reduction but did not affect cell survival. Thus, our results show that diminished staining with MTT in ouabain-treated cells is not sufficient proof of triggering of the cell death machinery. We speculate that altered endo- and exocytoses evoked by cardiotonic steroids contribute to decreased MTT reduction.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".