Impact of pyridoxine (B <sub>6</sub> ) deficiency on serine kinetics in the pig
Bibliographic record
Abstract
The water‐soluble vitamin B 6 serves a cofactor for serine hydroxymethyltransferase (SHMT), an enzyme critical to cellular one carbon flow. The current experiment was designed to test the alternate hypothesis that B 6 deficiency in an animal model will reduce SHMT activity and serine flux, as measured by stable isotopic dilution protocols. Pigs (commercial genotype; initial wt = 4.7 kg; n=6/treatment) were offered a basal semi‐purified diet (20.5% casein; 3474 kcal ME/kg) containing either 0 (B6−) or 3 (B6+) mg/kg pyridoxine·HCl for a 3 week feeding period, using a pair‐feeding design. At the end of the depletion period, a 6 hr primed (90 μmole/kg)‐constant (90 μmole/kg/h) infusion of L‐[2,3,3‐ 2 H 3 ] serine was administered via indwelling jugular vein catheter. Blood samples (femoral vein catheter) were collected at −60, 0, 60, 120, 180, 240, 300 and 360 min. Tissues were harvested at termination and samples processed for plasma serine m+3 enrichment (GC‐MS), plasma pyridoxal‐5‐phosphate (PLP; radioimmunoassay), and liver SHMT activity. Different superscripts indicate significant differences (P<0.05) by ANOVA F‐test. The current data allow us to accept the alternate hypothesis of a reduction in SHMT activity induced by dietary pyridoxine deficiency, with a concomitant reduction in serine flux. This reduction in serine flux may have implications for overall one‐carbon metabolism, including pathways linked to folate and sulfur amino acid metabolism. Support: Natural Sciences and Engineering Research Council of Canada (NSERC)
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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 | 0.001 | 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".