Methyl group partitioning during insufficient and excess availability via guanidinoacetate and creatine supplementation in young pigs
Bibliographic record
Abstract
Methionine is an essential amino acid that provides methyl groups for transmethylation (TM) reactions via S‐adenosylmethionine (SAM), resulting in S ‐adenosylhomocysteine (SAH), an inhibitor of TM reactions. Methylation of guanidinoacetate (GAA) to produce creatine (Cr) is proportional to GAA availability while Cr supplementation reduces GAA production and spares methyl groups. Our objective was to determine the partitioning of methyl groups among TM reactions under conditions of excess and insufficient methyl group availability. Three mo‐old pigs (n=18) were fed control, GAA‐ or Cr‐supplemented diets twice daily. On day 18, anesthesia was induced 1–3 h post feeding and a bolus of [methyl‐ 3 H]methionine was intravenously infused. After 30 min, the liver was analyzed for methyl‐ 3 H incorporation into protein, Cr, phosphatidylcholine (PC) and DNA. Compared to control (P<0.05), Cr and GAA led to a 200% and 700% increase in hepatic Cr concentration, respectively; GAA caused a 400% increase in total hepatic Cr methyl‐ 3 H incorporation. Unlike Cr pigs, GAA supplementation decreased methyl‐ 3 H incorporation into PC and decreased hepatic SAM concentration with no change in SAH, suggesting that creatine synthesis resulted in a limited methyl supply for PC synthesis (P<0.05). Creatine supplementation did not spare methyl groups, but GAA did lead to a limited methyl supply (CIHR). Grant Funding Source : 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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".