The Range of Oxygenation in SiHa Tumor Xenografts
Bibliographic record
Abstract
Tumor cells at very low oxygen tensions are known to be about three times more resistant to killing by ionizing radiation. Since cells at intermediate oxygen tensions (defined here as greater than 0.1% and less than 2% O(2)) show partial radioresistance, they should be a consideration in tumor treatment. In an effort to estimate the extent and range of oxygenation in SiHa human cervical carcinoma xenografts, patterns of cell killing and DNA damage by radiation and two bioreductive drugs, PD-144872 and RSU-1069, were compared to those seen in SiHa cells grown as spheroids. These drugs produce DNA interstrand crosslinks that are largely responsible for cell killing, and the degree of crosslinking increases as the oxygenation is reduced. About 60% of the cells in SiHa xenografts exhibited drug-induced crosslinks, but only about 35% showed extensive crosslinking indicative of hypoxia below 0.1% oxygen. Patterns of toxicity and DNA damage in xenografts were comparable to those of spheroids equilibrated with about 2% oxygen, indicating that most cells in the xenografts exhibit some radioresistance due to lack of oxygen. Similarly, pimonidazole binding indicated that about 60% of the cells in SiHa xenografts were either intermediate in oxygenation or hypoxic, but only about half of those were consistent with extreme oxygen depletion. The apparent size of the population of "intermediately hypoxic" cells has implications for the use of ionizing radiation, hypoxic cell cytotoxins, and other antitumor agents whose cytotoxicity is dependent on cellular oxygen content.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".