Objective To investigate the alterations of femoral biomechanics in streptozotocin (STZ) induced type 1 diabetic rats and the influnces of zoledronic acid (ZA).Methods The Type 1 diabetes mellitus models of rats were established by intraperitoneal injection of STZ .All 205 female Wistar rats were randomly assigned into the control group (n=40), the model group (n=55), the ZA prevention group ( n=55 ) and the ZA treatment group ( n=55 ) .ZA 0.1 mg/kg was given to the ZA prevention group immediately after the model establishment and to the ZA treatment group two weeks later .In each group, five rats were harvested randomly for performing the three-point bending test at the 1st, 2nd, 3rd, 4th, 5th, 8th, 12th and 16th weeks after the modeling.The structural mechanical indices (the maximum load and the elastic load) and the material mechanical indices (the elastic modulus and the energy absorption ) were obtained .Results The results showed all the mechanical indices in the control group increased during the 16 weeks.However, in the model group, the elastic modulus and energy absorption indices increased in the early five weeks , but decreased at the 8th week and the 12th week, then increased again to the highest level .The same trend was observed in the model group concerning the maximum load and the elastic load, while the differences were not statistically significant .The intergroup analysis showed that from the 1st week to the 5th week, there was no statistical difference among the groups .In the 8th week and the 12th week, the mechanics indices in the model group , the prevention group and the treatment group were all significantly lower than those in the control group (P<0.05);in the 16th week the indices varied. Conclusions The material mechanics of femur present greater changes than the structural mechanics . Zoledronic Acid could promote the biomechanical property , which was better in the prevention group than the treatment goup .

Objective To investigate the effects of a pulsed electromagnetic field (PEMF) on cell proliferation,differentiation and the genetic expression of osteogenesis specific transcription factor-Osterix (OSX) in the calvaria-derived osteoblasts of SD rats.Methods Primary osteoblasts were separated from the calvarias of Sprague-Dawley rats 24 hours after birth by trypsinazation and collagenase digestion.The osteoblasts at passage 4 were randomly divided into a control group and a PEMF group,Cells in the PEMF group were placed onto PEMF therapeutic apparatus and exposed to 11 mT radiation at 12 Hz for 1 h per day for 3 days.The osteoblasts' proliferation ability was then detected via methylthiazdyl tetrazolium assay.Alkaline phosphatase (ALP) activity in the cell lysate and the supernatant fluid was assayed through disodium phenyl phosphate colorimetric determination to determine the cells'differentiation ability.OSX mRNA expression was determined using real time reverse transcription polymerase chain reaction (RT-PCR).Results The proliferation of osteoblasts in the PEMF group was significantly greater than in the control group.PEMF exposure suppressed ALP activity in both the lysate and the supernatant of the osteoblasts.The OSX mRNA expression in the PEMF group was significantly down-regulated compared with the control group.Conclusion PEMF at 12 Hz and 11 mT can promote the proliferation of osteoblasts,but it inhibits cellular differentiation and down-regulates the mRNA expression of OSX.

Noggin是对机体多个系统的生长发育和重塑起重要调节作用的一种糖蛋白.其对神经系统和脑发育的影响已经为人们所熟知,近年来随着研究的不断深入,noggin对骨骼系统生长发育的显著作用逐渐被人们所认识:包括调节胚胎的形态发生,抑制体外成骨细胞增值与分化,抑制体内骨形成,调节颅缝融合和关节的正常形成以及辅助治疗骨肿瘤疾病等,是调节骨生长发育的重要细胞因子.其作用机制主要是通过与BMPs相互影响,调节BMPs信号通路的过程,间接调节骨形成.