Feeding Reduces Serum Concentration of Endogenous Bioactive (1-84), but Not Total Intact Parathyroid Hormone in Female Sprague-Dawley Rats
Bibliographic record
Abstract
Background: Interpretation of parathyroid hormone (PTH) measurements requires an understanding of its structural conformation. PTH reflects calcium intake and vitamin D status but is commonly measured in the fasted state using 2nd generation assays, known to cross-react with PTH 7-84 fragments, which is not observed with 3rd generation assays. The objective was to determine if plasma PTH in the fed and non-fed state differ while controlling for diurnal rhythm and the generation of PTH assay. Methods: Blood was sampled, 2 d apart, from Sprague-Dawley rats (30 males and 30 females) in both fed and non-fed states at 20 wk of age (weight: 470.2 ± 23.2 g) for measurement of ionized calcium (iCa), total intact (INT) and bioactive 1-84 (BIO) PTH. Differences between groups were tested using a GLIMMIX model with sex and feeding state as fixed effects and individual rats as a random effect. Results: Females had a lower iCa than males (F: 1.43 ± 0.01 vs M: 1.46 ± 0.01 mmol/L, P = 0.03). In males and females, there was no difference between fed and non-fed groups when PTH was assessed using the INT PTH assay (M Fed: 21.6 ± 1.3 vs M Non-fed: 22.6 ± 2.3 pmol/L, P = 0.59; F Fed: 19.3 ± 1.5 vs F Non-fed: 22.8 ± 2.9 pmol/L, P = 0.39). However, in females only, PTH measured using the BIO PTH, was significantly lower in the fed group versus the non-fed (Fed: 8.4 ± 0.8 vs Non-fed: 16.7 ± 3.4 pmol/L, P = 0.05). Conclusions:
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".