Role of Parathyroid Hormone (PTH) and PTH-related Protein (PTHrP) in Regulating Mineral Homeostasis during Fetal Development
Bibliographic record
Abstract
Parathyroid hormone (PTH) and PTH-related protein (PTHrP) play complementary and overlapping roles in regulating fetal mineral homeostasis. PTHrP is expressed within the growth plate, directs endochondral bone formation, and determines the fate of chondrocytes before bone formation can be initiated. It is expressed in placenta and is present at high levels in the fetal circulation. It stimulates placental calcium (and possibly magnesium) transfer and raises blood mineral levels above ambient maternal values in order to effect mineralization of the skeleton. It does not upregulate in response to absence of PTH or hypocalcemia, and thus, its secretion may be regulated autonomously or in response to placental signals. PTH is expressed in fetal parathyroids and placenta. Despite circulating at low levels, it has a more dominant effect than PTHrP in regulating the blood calcium and ensuring adequate mineralization of the skeleton. It may also have effects on bone formation in the steps that occur after apoptosis of hypertrophic chondrocytes. Unlike PTHrP, it increases with fetal hypocalcemia, but its secretion is constrained by the calcium-sensing receptor to maintain the adult calcium level, well below what the fetus normally achieves. PTH also stimulates placental calcium transfer, and its absence disrupts placental expression of calciotropic and cation transporter genes.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
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".