Vascular Endothelial Growth Factor in Rabbits During Development of Corticosteroid-Induced Osteonecrosis: A Controlled Experiment
Bibliographic record
Abstract
OBJECTIVE: Vascular endothelial growth factor (VEGF) is an angiogenic promoter that is rapidly induced as a response to local hypoxia. We investigated VEGF expression in rabbits in a controlled experiment to clarify the onset of ischemic events in corticosteroid-induced osteonecrosis (ON). METHODS: Ninety-nine mature Japanese white rabbits were divided into 6 treatment groups and an untreated control group. The treatment groups received a single intramuscular injection of 4 mg/kg methylprednisolone acetate; they were euthanized at different times, and tissue samples were obtained from their femora. We examined the development of ON and the expression of VEGF using histopathology, immunohistochemistry, Northern blot analysis, and Western blot analysis. RESULTS: On histopathological examination, the earliest indication of ON was 5 days after the corticosteroid treatment. The frequency of ON occurrence reached a plateau at or after Week 1. VEGF expression was accompanied by the development of ON. VEGF-positive cells detected by immunohistochemistry were found among bone marrow cells, frequently located in the area surrounding ON, suggesting that VEGF production was switched on as a result of the ischemic events that cause ON. The level of VEGF-mRNA expression indicated by Northern blot analysis peaked at 3 days after the corticosteroid treatment and decreased gradually to the levels present in the control group at 7 days after treatment. Western blot analysis revealed VEGF protein production at 3 days after the corticosteroid treatments. Levels of VEGF expression 2 weeks or more after the corticosteroid treatment were almost the same as in the control group. CONCLUSION: We observed early expression of VEGF in the cells around the corticosteroid-induced ON lesions in rabbits. These results suggest that the ischemic events that cause ON begin soon after the initial corticosteroid treatment.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| 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".