Bone
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Pulsed electromagnetic fields (PEMF) have been proved effective in the prevention of osteoporosis both experimentally and clinically. Chronotherapy studies have shown that circadian rhythm (CR) played an important role in the occurrence, development and treatment of several diseases. CR has also been recognized as an essential feature of bone metabolism. ⋯ Furthermore, the bone turnover biomarkers (serum alkaline phosphatase, serum bone Gla protein and urinary deoxypyridinoline) and the dynamic histomorphometric parameters reflecting the trabecular osteoblast and osteoclast activity (bone formation rate with bone volume as referent, osteoclast number, etc.) in the OVX+DPEMF group decreased to a larger extent compared with the OVX+NPEMF group. In conclusion, the results indicated that CR was an important factor determining the preventive effect of PEMF on osteoporosis and PEMF exposure in the daytime presented better stimulus efficacy in rats. The findings might be helpful for the efficacious use of PEMF mediations, evaluation of PEMF action and experimental design in the future studies of biological effect of electromagnetic fields.
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Animal model for heterotopic ossification (HO) induced by Achilles tenotomy in rats has been used in the literature. However, the molecular mechanism remains unclear. Here, we studied bone and cartilage related genes and their possible roles in this model. ⋯ The presences of the proteins of HIF-1 alpha, Sox9, Runx2, TGF-betas and BMPs within the HO tissues were confirmed by immunohistochemical staining. Our study indicates that HO induced by Achilles tenotomy is by endochondral bone formation, and HIF-1 alpha activation plays an important role during chondrogenesis in this model. Furthermore, the model provides a new experimental system to study endochondral ossification.
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Randomized Controlled Trial
Serum 25-hydroxyvitamin D levels in vitamin D-insufficient hip fracture patients after supplementation with ergocalciferol and cholecalciferol.
Vitamin D insufficiency is commonly associated with hip fracture. However, the equipotency of ergocalciferol and cholecalciferol supplementation in this patient group has not been studied in a randomized trial using high-performance liquid chromatography (HPLC) measurement of serum 25-hydroxyvitamin D (25OHD). The objective of this study was to determine if ergocalciferol and cholecalciferol are equipotent therapies in vitamin D-insufficient hip fracture patients. ⋯ Changes in iPTH and wPTH were not significantly different between calciferol treatments (p>0.05). In vitamin D-insufficient hip fracture patients, supplementation with cholecalciferol 1000 IU/day for three months was more effective in increasing serum 25OHD than an equivalent dose of ergocalciferol. However, the lack of difference in PTH lowering between calciferol treatments raises questions about the biological importance of this observation.
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Osteogenic cell proliferation and differentiation play an important role in adequate fracture healing, and is target for osteoinductive therapies in delayed fracture healing. The aim of this study was to investigate whether low-intensity pulsed ultrasound enhances fracture healing at the tissue level in patients with a delayed union of the osteotomized fibula through an effect on the presence of RUNX2 immunopositive osteogenic cells. The effect was studied in both atrophic and hypertrophic delayed unions. ⋯ Immunolocalization of RUNX2 positive cells in delayed unions of the fibula reveals that delayed clinical fracture healing does not result in impairment of osteogenic cell proliferation and/or differentiation at the tissue level, even if delayed unions are clinically regarded as atrophic. Reduced number of osteogenic RUNX2 immunopositive cells within the soft connective tissue, and unchanged number of RUNX2 immunopositive cells at the bone surface, implicate that low-intensity pulsed ultrasound does not increase osteogenic cell presence, but likely affects osteogenic cell differentiation.
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Recent large trials indicate that adherence associated with a daily regimen of vitamin D is low and limits anti-fracture efficacy with vitamin D supplementation. The aim of this report is to describe changes of 25-hydroxyvitamin D (25(OH)D) serum concentrations achieved with a single oral dose of 300000 IU vitamin D3. ⋯ Based on our observations, a single oral dose of 300000 IU vitamin D3 raises mean 25(OH)D serum concentrations to the target mean of above 75 nmol/l at 3 months and a mean level of 69 nmol/l at 6 months. As calcium absorption is enhanced with higher 25(OH)D serum concentrations, calcium supplementation may need downward adjustment with this regimen to avoid mild hypercalcemia.