Liquid Chromatography–Tandem Mass Spectrometry Analysis of Erythrocyte Thiopurine Nucleotides and Effect of Thiopurine Methyltransferase Gene Variants on These Metabolites in Patients Receiving Azathioprine/6-Mercaptopurine Therapy
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
BACKGROUND: Polymorphic thiopurine S-methyltransferase (TPMT) is a major determinant of thiopurine toxicity. METHODS: We extracted 6-thioguanine nucleotides (6-TGNs) and 6-methylmercaptopurine nucleotides (6-MMPNs) from erythrocytes with perchloric acid and converted them to 6-thioguanine (6-TG) and a 6-methylmercaptopurine (6-MMP) derivative during a 60-min acid hydrolysis step. The liquid chromatography system consisted of a C(18) column with an ammonium acetate-formic acid-acetonitrile buffer. 8-Bromoadenine was the internal standard. Analytes were measured with positive ionization and multiple reaction monitoring mode. With PCR-restriction fragment length polymorphism analysis and TaqMan allelic discrimination, common TPMT alleles (*1, *2, *3A, *3B, *3C) were determined in 31 792 individuals. We used perchloric acid extraction, acid hydrolysis, and HPLC with ultraviolet detection to measure erythrocyte 6-TG and 6-MMP nucleotide concentrations in 6189 patients with inflammatory bowel disease receiving azathioprine/6-mercaptopurine therapy. RESULTS: Intra- and interday imprecision were <10% at low and high analyte concentrations. The conversion of 6-TG and 6-MMP nucleoside mono-, di-, and triphosphates was complete after hydrolysis. Allelic frequency for TPMT variant alleles ranged from 0.0063% (*3B) to 3.61% (*3A). Compared with wild types, TPMT heterozygotes had an 8.3-fold higher risk for 6-TGNs >450 pmol/8 x 10(8) erythrocytes (concentration associated with increased risk for leukopenia), but an 8.2-fold lower risk for 6-MMPNs >5700 pmol/8 x 10(8) erythrocytes (concentration associated with increased risk for hepatotoxicity). CONCLUSIONS: The liquid chromatography-tandem mass spectrometry method can be applied to the routine monitoring of thiopurine therapy. The association between TPMT genotype and metabolite concentrations illustrates the utility of pharmacogenetics in the management of patients undergoing treatment with thiopurines.
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.
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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 it