HESI GTTC ring trial: Concordance between Ames and rodent carcinogenicity outcomes for N-nitrosamines (NAs) with rat and hamster metabolic conditions
Bibliographic record
Abstract
A multi-sector study (i.e., Ring Trial) was designed to improve the in vitro detection of N -nitrosamine (NA)-associated mutagenicity by optimizing the bacterial reverse mutation (i.e., Ames) assay protocol and testing various conditions on the sensitivity and specificity for the prediction of rodent carcinogenicity. A total of 29 NAs and 3 N -nitroso drug-like compounds from different structural classes and carcinogenicity outcomes were tested (two independent laboratories per compound) across 5 bacterial strains using a 30-min pre-incubation protocol. To evaluate the impact of different metabolic activating systems (MASs), testing conditions included the use of 10 or 30 % liver S9 fractions prepared from rats or hamsters pretreated with inducers of enzymatic activity. Results indicate that E. coli and Salmonella typhimurium strains detecting single base pair mutations, coupled with MASs containing 30 % hamster S9s were the most sensitive (90 %) for identifying NAs that are rodent carcinogens. Regarding MAS combinations, the highest sensitivity was 30 % rat and 30 % hamster (93 %), but has low specificity (45 %), with good laboratory agreement for the Ames calls (91 %). DMSO and water were considered suitable solvents, except for small-molecular weight alkyl NAs. These results will support harmonized Ames testing of NAs, giving high confidence for a negative result. • 30 % hamster S9 had the highest sensitivity of all individual MASs. • 30 % S9 (rat or hamster) had a higher sensitivity than 10 % S9 (rat or hamster). • -S9 and 30 % rat and hamster S9 had high sensitivity (93 %) but low specificity (45 %). • Specificity was similar amongst S9 species or concentration. • DMSO and water were suitable solvents for NA Ames testing.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".