SPECIFIC RESPONSES OF HUMAN FACIAL BONE TO MECHANICAL LOADING

二○ ○一年：在我们的对照实验中，骨细胞对拉伸有反应，上调了c-fos、考克斯-2、骨钙素和IGF mRNA等信息的稳态水平。由于拉伸骨细胞中机械传导的一个基本特征是对PTH-cAMP-PKA通路的协同串扰。本研究通过RT-PCR检测骨细胞对低强度脉冲超声无反应，与拉伸骨细胞相比，同一骨来源的成骨细胞对低强度脉冲超声的反应是上述mRNA的上调。此外，我们研究了甲状旁腺素和超声波之间的串扰在成骨细胞来源于原代人牙槽骨。仅观察到累加效应。很明显，脉冲超声与拉伸的路径不同，但两者都导致骨生成。2002：因此，我们预期整合素途径是细胞分化的结果，并通过FAK或PYK 2的蛋白质印迹分析研究了该途径，抗p-Tyr抗体免疫沉淀成骨细胞和骨细胞后，暴露超声后p38和ERK酪氨酸磷酸化。进行蛋白质印迹分析以确定p-PYK 2和p-p38的水平。一个125 kDa的蛋白质显示，在成骨细胞暴露于US的酪氨酸磷酸化水平增加。相反，在成骨细胞中，p-ERK的磷酸化酪氨酸信号并没有增加。结果表明，超声波照射可诱导成骨细胞分化。在这项研究中，我们认为这可能是为什么SAFHS在牵张成骨中加速骨成熟非常有效的原因，它施加静态拉力并缩短潜伏期。

2001 : In our control experiments, osteocytes responded to stretching, upregulating the steady-state levels of the messages such as c-fos, COX-2, osteocalcin and IGF mRNA. Since an essential feature of mechanotranduction in stretched osteocytes is the synergistic crosstalk to the PTH-cAMP-PKA pathway. In this study, osteocytes did not respond to low-intensity pulsed ultrasound as far as the messages such as c-fos, osteocalcin and IGF are analyzed by RT-PCR.Compared with stretched osteocyte, osteoblasts derived from same bone respond to low-intensity pulsed ultrasound as upregulation of abovementioned m-RNA. In addition, we studied the crosstalk between PTH and the ultrasound in osteoblasts derived from primary human alveolar bone. There was only additive effect observed.It was apparent that pulsed ultrasound take different pathways from those of stretching, while both leading to osteogenesis.2002 : So we expected the pathway of integrins as result of cell differentiation and studied the pathway by western blot analysis for FAK or PYK2, p38 and ERK tyrosine phosphrylation after immunoprecipitation of anti-p-Tyr antibody against osteoblast and osteocyte with exposing ultrasound. Western blot analysis was performed to determine the levels of p-PYK2 and p-p38. A 125 kDa protein showed increasing levels of tyrosine phosphorylation in osteoblast exposing to US. On the contrary, in the level of p-ERK, this phosphotyrosine signal do not increased in osteoblast exposing to US. The result showed exposed ultrasound lead to cell differentiation in osteoblasts. In this study, we believe that is probably why SAFHS is extremely effective in accelerating bone maturation in distraction osteogenesis, which applies static tensile force and shorten the latency period.