Deficient Bone Formation in Idiopathic Juvenile Osteoporosis: A Histomorphometric Study of Cancellous Iliac Bone
Bibliographic record
Abstract
Idiopathic juvenile osteoporosis (IJO), a rare cause of osteoporosis in children, is characterized by the occurrence of vertebral and metaphyseal fractures. Little is known about the histopathogenesis of IJO. We analyzed by quantitative histomorphometry iliac crest biopsies from 9 IJO patients (age, 10.0-12.3 years; 7 girls) after tetracycline labeling. Results were compared with identically processed samples from 12 age-matched children without metabolic bone disease and 11 patients with osteogenesis imperfecta type I. Compared with healthy controls, cancellous bone volume (BV) was markedly decreased in IJO patients (mean [SD]: 10.0% [3.1%] vs. 24.4% [3.8%]), because of a 34% reduction in trabecular thickness (Tb.Th) and a 37% lower trabecular number (Tb.N; p < 0.0001 each; unpaired t-test). Bone formation rate (BFR) per bone surface was decreased to 38% of the level in controls (p = 0.0006). This was partly caused by decreased recruitment of remodeling units, as shown by a trend toward lower activation frequency (54% of the control value; p = 0.08). Importantly, osteoblast team performance also was impaired, as evidenced by a decreased wall thickness (W.Th; 70% of the control value; p < 0.0001). Reconstruction of the formative sites revealed that osteoblast team performance was abnormally low even before mineralization started at a given site. No evidence was found for increased bone resorption. Compared with children with osteogenesis imperfecta (OI), IJO patients had a similarly decreased cancellous BV but a much lower bone turnover. These results suggest a pathogenetic model for IJO, in which impaired osteoblast team performance decreases the ability of cancellous bone to adapt to the increasing mechanical needs during growth. This will finally result in load failure at sites where cancellous bone is essential for stability.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.000 | 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 teacher head, 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".