Fractional synthesis rate of creatine from arginine in healthy adult men
Bibliographic record
Abstract
Creatine is synthesized from the amino acids arginine, glycine and methionine. We performed a study using 15 N 2 ‐guanidino arginine, to elucidate synthesis of creatine from dietary arginine in adult men. A primed, intermittent infusion of labeled 15 N 2 ‐guanidino arginine was given enterally to 5 healthy men fed a standardized milkshake diet. Blood was sampled at baseline and at plateau, between 1.5 and 3 hours. Enrichment of M+2 isotopomers of arginine, guanidino acetate (GAA), creatine and creatinine was measured by LC‐tandem MS. Plasma enrichment of the arginine tracer was 6.1 APE (Stdev ±1.05%), giving a flux estimate of 93 ìmol/kg/hr. M+2 isotopomers of creatine and GAA from the arginine tracer were detected in all subjects. There was no measurable M+2 creatinine. Enrichment of creatine was 0.55 APE (±0.1%) and GAA 4.92 APE (±0.8%). The fractional synthesis rate of GAA from arginine was 81% and 9% for creatine from arginine, these results are in keeping with synthesis of GAA being the rate limiting step in the creatine synthesis pathway. We have demonstrated synthesis of creatine from labeled dietary arginine in healthy adult humans; this method will allow in vivo studies in humans to directly measure synthesis rates of creatine. Supported by a grant from the CIHR.
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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 | 0.000 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".