Characterisation of an Inhibitor of Thymidine Uptake Produced by Cultured Human Melanoma Cells
Bibliographic record
Abstract
Supernatants of established cultures of human neoplastic and normal cells have been shown to contain a number of different biological activities, including inhibition of DNA synthesis as measured by thymidine uptake. We have found that supernatants of melanoma cell lines contain an inhibitor of thymidine uptake which is heat labile, ultraviolet sensitive, non-filtrable (0.22 mu) and partially sedimentable at 20,000 x g. The mechanism of action of the inhibitor involves the degradation of 3H-thymidine to a non-utilisable form, which we detect by failure of uptake of 3H-thymidine by cultures of mitogen stimulated lymphocytes to which the inhibitor is added. While microbiological tests have failed to reveal mycoplasma contamination of inhibitor producing cultures, treatment of these cultures with kanamycin suppresses inhibitor production. Qualitative evaluation of DNA synthesis by the inhibitor producing cultures using autoradiography and fluorescent DNA staining has confirmed the presence of mycoplasma. With the widespread use of established cell lines in cancer research, it is imperative that screening for mycoplasma contamination go beyond routine microbiological assays. Detection of 3H-thymidine degradation by cell culture supernatants is an additional simple and sensitive indirect test which could be used for this purpose.
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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) | 0.001 | 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".