Alternative markers for Methylnortestosterone misuse in human urine
Bibliographic record
Abstract
Methylnortestosterone is a progestin and synthetic androgenic anabolic steroid, prohibited by WADA. Methylnortestosterone misuse is commonly detected by monitoring the parent compound and its main metabolites, 17α-methyl-5α-estrane-3α, 17β-diol (M1) and 17α-methyl-5β-estrane-3α, 17β-diol (M2), in the glucuronide fraction. In the current study, a direct detection of methylnortestosterone sulfo-conjugated metabolites after ethyl acetate extraction and analysis by LC/Q/TOF-MS in negative ionization mode was performed, detecting two main sulfate metabolites (S1, S2). For the characterization of metabolites, samples from the excretion study, were additionally analyzed by GC-MS, after solvolysis and per TMS derivatization. RT and MS data collected, were compared with RT and MS data from metabolites of 17z-methyl-5α/β-estrane-3α/β, 17z-diols structures with prefixed stereochemistry at 3 and 5 positions, synthesized through Grignard reaction from 19-noretiocholanolone, 19-norandrosterone and 19-norepiandrosterone. Confirmed sulfate metabolites were S1, 17α-methyl-5α-estrane-3α, 17β-diol 3α sulfate (detected up to 72 h) and S2, 17α-methyl-5β-estrane-3α, 17β-diol 3α sulfate (detected up to 192 h). Furthermore, applying targeted analysis based on RT and MS data of the synthesized metabolites two additional metabolites M3, 17β-methyl-5β-estrane-3α, 17α-diol and M4, 17β-methyl-5α-estrane-3α, 17α-diol were detected in the glucuronide fraction and one more metabolite (S3) 17β-methyl-5β-estrane-3α, 17α-diol was detected in the sulfate fraction in lower abundance until the end of the excretion study (192 h). Interestingly, S2 could also be detected after the direct analysis of non-hydrolyzed steroid by GC-MS/MS as artifact, following normal ProcIV anabolic steroid procedure and using diethylether as extraction solvent.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".