090 The hydroxyproline–glycine pathway for gl.ycine synthesis in neonatal pigs
Bibliographic record
Abstract
Glycine has crucial roles in nutrition and metabolism and is the most abundant AA in the plasma of newborn pigs (approximately 1 mM; 2- to 3-fold greater concentrations than in plasma of other species). Quantitative analysis has shown that the classic pathways for glycine synthesis (from serine, threonine, and choline) are insufficient to meet the metabolic requirements of neonatal pigs. Therefore, we hypothesized that there is an additional pathway for endogenous synthesis of glycine. On d 1, 7, 14, and 21 of lactation, milk samples were obtained from 6 sows. Six piglets were euthanized on each of those days to obtain plasma and tissue samples for analyses of AA, enzyme activities, and expression of proteins and mRNA. Data were analyzed by 1-way ANOVA. Our results indicated high concentrations of hydroxyproline as a tripeptide in sow's milk and plasma from piglets. The specific activities of hydroxyproline oxidase (OH-POX), alanine:glyoxylate aminotransferase, and 4-hydroxy-2-oxoglutarate aldolase, which are key enzymes for synthesis of glycine from hydroxyproline, decreased (P < 0.05) in the liver and kidneys between d 1 and 21 but increased (P < 0.05) in the pancreas and small intestine. Similar results were obtained for the expression of mRNA for those enzymes and for proline oxidase (POX). For the serine- and threonine-dependent glycine pathways, specific activities and expression of mRNA for serine hydroxymethyltransferase and threonine dehydrogenase increased (P < 0.05) between d 1 and 21. Immunohistochemistry (IHC) revealed that the localization of OH-POX and POX proteins in the liver switched from periportal to perivenous hepatocytes with age, which indicated a change in hepatic catabolism of hydroxyproline and proline. In the kidneys, the abundance of OH-POX and POX proteins appeared to decrease with age. Results of IHC also revealed the presence of OH-POX and POX in the pancreas, small intestine, stomach, skeletal muscle, and gallbladder. These findings indicate the presence of the hydroxyproline–glycine pathway for the synthesis of glycine from milk- and endogenous collagen–derived hydroxyproline via interorgan metabolism in neonatal pigs, which may compensate for a severe deficiency of glycine in sow's milk. Supported by funds from the USDA National Institute of Food and Agriculture.
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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) | 0.000 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".