Cell cycle progression and radiation survival following prolonged hypoxia and re-oxygenation
Bibliographic record
Abstract
PURPOSE: To investigate cell cycle progression and radiation survival following prolonged hypoxia and re-oxygenation. MATERIALS AND METHODS: NHIK 3025 human cervical carcinoma cells were exposed to extremely hypoxic conditions (<4ppm O2) for 20 h and then re-oxygenated. The subsequent cell cycle progression was monitored by analysing cell cycle distribution at different time-points after re-oxygenation using two-dimensional flowcytometry. The clonogenic survival after a 3.6 Gy X-ray dose was also measured at each of these time-points. The measured radiation survival was compared with theoretical predictions based on cell cycle distribution and the radiation age response of the cells. RESULTS: Following re-oxygenation the cells resumed cell cycle progression, completed S-phase, and then accumulated in G2. Non-clonogenic cells remained permanently arrested in G2, while the remainder of the cells completed mitosis after a few hours delay. The radiation survival of the hypoxia-pretreated cell population remained lower than for an exponentially growing control population for the investigated 50h of re-oxygenation. However, following 7 h of re-oxygenation, the radiation survival of the hypoxia-treated cell population correlated well with theoretically predicted values based on cell cycle distribution and radiation age response. CONCLUSIONS: The work demonstrates that prolonged hypoxia followed by re-oxygenation results in a G2 delay similar to that observed after DNA damage. Furthermore, chronic hypoxia results in decreased radiation survival for at least 50h following the reintroduction of oxygen. The hypoxia-induced radiosensitization following 7 h of re-oxygenation could in large part be explained by the synchronous cell cycle progression that occurred.
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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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".