Mechanical stimuli may prevent osteoporosis in ovariectomized rats

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Abstracts / Bone 47 (2010) S385–S458

204 Mechanical stimuli may prevent osteoporosis in ovariectomized rats Dong Zhu1, Jiazi Gao2, Renshi Ma1, He Gong2, Xizheng Zhang1,3 1 Department of Traumatology, First Hospital of Jilin University, Changchun, China 2 College of Mechanism Science & Engineering, Jilin University, Changchun, China 3 Institute of Medical Equipment, Military Medical Science Academy of the PLA, Tianjin, China Objective: This research is to determine whether intermittent vibration would inhibit the loss of bone in ovariectomized rats. Methods: Forty-two female Wistar rats 6 months of age were allocated into the following six groups randomly: IVO (intermittent vibration group with interval of one day), IVT (with interval of two days), IVF (with interval of two days), IVS (with interval of seven days), CVG (continuous vibration group) and OCG (ovariectomized control group). All the animals were subjected to ovariectomy. One week later, the intermittent mechanical signal, with frequency of 32– 37 Hz and acceleration of 0.3 g, were loaded to all the rats for 15 min each day except OCG. The femurs were scanned by micro-CT after sacrifice at the 8th and 12th week, respectively. Results: The trabecular separation in the OCG is significantly higher than that in all the vibration groups at the 8th week, while the opposite result is shown in trabecular thickness, volume percentage and trabecular number. The minimum separation is observed in IVS, while the less higher value is shown in CVG, IVT and IVF. The maximum trabecular thickness is shown in IVS and CVG, and the following groups are in descending order: IVF, IVT and IVO. IVF shows the highest value of trabecular percentage, and IFS, IVT, IVO and CVG shows a descending order. There was no significant difference between all the vibration groups and ovariectomized control group except IVS and IVF. Conclusions: An intermittent mechanical signal can prevent osteoporosis dramatically, especially at premenopause. An intermittent mechanical signal with an interval of seven days would prevent osteoporosis in twelve weeks very well, but the long-term outcome and affect to the peripheral nerve is still under discovery. Acknowledgments This work is supported by the National Natural Science Foundation of China (nos. 10832012 and 10872078) and the Scientific Advancing Front and Interdiscipline Innovation Project of Jilin University (no. 20090372). doi:10.1016/j.bone.2010.09.211

205 The therapeutic response to Alendronate in postmenopausal Chinese women with osteoporosis and N740N polymorphism of low density lipoprotein receptor related protein 5 (LRP5) gene Wenzhen Fu, Yaohua Ke, Zhenlin Zhang Department of Osteoporosis & Bone Diseases, Metabolic Bone Disease & Genetic Research Unit, Shanghai JiaoTong University Affiliated Sixth People's Hospital, Shanghai, China Objective: To investigate whether the change of bone mineral density (BMD) after Alendronate one-year treatment in postmenapausal women with osteoporosis associates with the N740N polymorphism of low density lipoprotein receptor related protein 5 (LRP5) gene and determine the correlation between genotypes and the therapeutic effect. Methods: Sixty-seven postmenopausal osteoporotic patients were recruited with an average age of 64.2 ±7.7 years. Every patient took

oral Alendronate (Forsamax) 70 mg weekly and Caltrate 600 mg daily for 12 months. Pre- and post-treatment, bone mass density was measured at the lumbar spine 2–4 and left hip sites. PCR-RELP was performed for the N740N polymorphism of low density lipoprotein receptor related protein 5 (LRP5) gene. Results: One year therapy was accomplished in 63 patients. Compared with the baseline BMD, the posttreatment BMD was increased significantly at all sites. The BMD of lumbar spine 2–4 was increased 5.48 ± 4.68%, while the BMD of the femoral neck was increased 1.77 ± 4.72%, the BMD of trochanter was increased 3.81 ± 5.10%, the BMD of the inter-trochanter was increased 2.60 ± 3.14%; and the BMD of total hip was increased 2.50 ± 3.14%. Conclusion: The BMD of the lumbar spine was increased more significantly than the BMD of the hip sites in postmenopausal osteoporotic Chinese women after one-year alendronate therapy. But there was no correlation between the therapeutic response and the N740N polymorphism of low density lipoprotein receptor related protein 5 (LRP5) gene. Larger studies are needed to confirm these results. doi:10.1016/j.bone.2010.09.212

208 Establishment of normal female reference for high-resolution peripheral quantitative computed tomography (HR-pQCT) in the Chinese population Tsz Ning Fong, Vivian Wing-yin Hung, Fiona Wai-ping Yu, Leung-kim Hung, Ling Qin Department of Orthopaedics & Traumatology, Bone Quality & Health Assessment Centre, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China Objective: High resolution peripheral quantitative computed tomography (HR-pQCT) is a 3D technology that measures the true volumetric BMD (vBMD) and structural parameters. Currently, normal dataset of HR-pQCT has been established in Caucasian, but not Asian populations. This study was aimed to establish a normal reference database for both distal radius and distal tibia in the Chinese female population using non-invasive HR-pQCT. Methods: Normal females at age 25 to 89 were recruited (n = 242). Women undertaking medications or surgery that may affect bone metabolism were excluded. Standard scans on non-dominant distal radius and tibia, with scanning resolution of 82 mm, were performed using HRpQCT (XtremeCT, Scanco Medical AG, Switzerland). Short-term precision error test for the HR-pQCT was also performed in 34 cases. Precision error was expressed by coefficient of variation (C.V.). Results: Our results showed that, at the distal radius, all vBMDs (Dtotal, Dtrab and Dcortical) increased from the age of 25 and reached the peak at mid 30s. After mid 30s, vBMDs had a mild drop until mid 50s, followed by a drastic drop after age 55. Among all vBMDs, Dtrab dropped from the mid 30s and Dcortical dropped after the mid 40s. At the time of menopause (age 55 in this study), BV/TV, trabecular thickness (Tb.Th) and trabecular number (Tb.N) decreased; however, trabecular separation (Tb.Sp) was increased. Short-term C.V. for density and structural parameters ranged from 0.25% to 3.73% at the distal extremities. Discussion and conclusion: This is the first study to establish a normal HR-pQCT reference dataset in vBMD as well as microarchitecture of distal extremities in the Chinese female population. Our results revealed that peak vBMDs were found at the mid 30s and a remarkable decline at the mid 40s. Significant changes of bone microarchitecture were shown after the age of menopause. Our results on short-term precision error were comparable to other published data. The establishment of the normal HR-pQCT reference in Chinese females may serve as the basis for comparison of diagnosis sensitivities of osteoporosis and also be