Preparation of Antibodies for the Designer Steroid Tetrahydrogestrinone and Development of an Enzyme-Linked Immunosorbent Assay for Human Urine Analysis
Bibliographic record
Abstract
A highly sensitive enzyme-linked immunosorbent assay (ELISA) has been developed for tetrahydrogestrinone (THG), the new designer anabolic steroid responsible for the well-known Balco scandal announced in year 2003. Antibodies have been raised against 18a-homo-pregna-4,9,11-trien-17beta-ol-3-carboxymethyl oxime coupled to horseshoe crab hemocyanin. The hapten has been synthesized from gestrinone by controlled reduction of the triple bond of the ethinyl group at position C-17, without affecting the double bonds of the steroidal rings, followed by reaction of the keto group at C-3 with (carboxymethoxy)amine hemihydrochloride to form the oxime bond. The antisera obtained has been used in combination with 18a-homo-pregna-4,9,11-trien-17beta-ol-20-yn-3-carboxymethyl oxime, a hapten derivative of gestrinone, coupled to bovine serum albumin to establish a competitive ELISA. Under the conditions used, THG can be detected in buffer with a limit of detection (LOD) of 0.045 +/- 0.015 microg L(-1) (N = 9). The assay is very selective since other steroids assessed are not recognized. Preliminary experiments performed with human urine samples demonstrate that the assay can be applied to the analysis of these samples after a simple sample treatment method reaching a LOD of 0.25 +/- 0.14 microg L(-1). Accuracy is very good as demonstrated by the excellent correlation obtained when analyzing blind spiked urine samples (slope 0.93, R2 = 0.992).
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.003 |
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".