Simultaneous detection of stable isotope‐labeled and unlabeled <scp>l</scp>‐tryptophan and of its main metabolites, <scp>l</scp>‐kynurenine, serotonin and quinolinic acid, by gas chromatography/negative ion chemical ionization mass spectrometry
Bibliographic record
Abstract
A method for the detection of unlabeled and (15)N2 -labeled L-tryptophan (L-Trp), L-kynurenine (L-Kyn), serotonin (5-HT) and quinolinic acid (QA) in human and rat plasma by GC/MS is described. Labeled and unlabeled versions of these four products were analyzed as their acyl substitution derivatives using pentafluoropropionic anhydride and 2,2,3,3,3-pentafluoro-1-propanol. Products were then separated by GC and analyzed by selected ion monitoring using negative ion chemical ionization mass spectrometry. L-[(13)C11, (15)N2]-Trp, methyl-serotonin and 3,5-pyridinedicarboxylic acid were used as internal standards for this method. The coefficients of variation for inter-assay repeatability were found to be approximately 5.2% for L-Trp and (15)N2-Trp, 17.1% for L-Kyn, 16.9% for 5-HT and 5.8% for QA (n = 2). We used this method to determine isotope enrichments in plasma L-Trp over the course of a continuous, intravenous infusion of L-[(15) N2 ]Trp in pregnant rat in the fasting state. Plasma (15)N2-Trp enrichment reached a plateau at 120 min. The free Trp appearance rate (Ra) into plasma was 49.5 ± 3.35 µmol/kg/h. The GC/MS method was applied to determine the enrichment of (15)N-labeled L-Trp, L-Kyn, 5-HT and QA concurrently with the concentration of non-labeled L-Trp, L-Kyn, 5-HT and QA in plasma. This method may help improve our understanding on L-Trp metabolism in vivo in animals and humans and potentially reveal the relative contribution of the four pathways of L-Trp metabolism.
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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 | 0.001 | 0.008 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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 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".