SPECIFIC RESPONSES OF HUMAN FACIAL BONE TO MECHANICAL LOADING

2001：在我们的对照实验中，骨细胞对拉伸作出反应，上调稳态水平的信息，如c-fos， COX-2，骨钙素和IGF mRNA。因为拉伸骨细胞机械传导的一个基本特征是与PTH-cAMP-PKA通路的协同串扰。本研究中，通过RT-PCR分析低强度脉冲超声对骨细胞c-fos、骨钙素、IGF等信息无响应。与拉伸的骨细胞相比，来自同一骨的成骨细胞对低强度脉冲超声的反应是上述m-RNA的上调。此外，我们还研究了原代人牙槽骨成骨细胞中甲状旁腺激素与超声之间的串扰。只观察到加性效应。很明显，脉冲超声与拉伸超声的路径不同，但两者都导致成骨。2002：因此，我们期望整合素作为细胞分化的结果，并通过western blot分析FAK或PYK2， p38和ERK酪氨酸磷酸化的途径，免疫沉淀抗p- tyr抗体对抗成骨细胞和骨细胞暴露超声。Western blot检测p-PYK2和p-p38水平。在暴露于US的成骨细胞中，125 kDa蛋白显示酪氨酸磷酸化水平增加。相反，在p-ERK水平上，这种磷酸酪氨酸信号在暴露于US的成骨细胞中没有增加。结果表明，暴露超声诱导成骨细胞分化。在这项研究中，我们认为这可能就是为什么SAFHS在牵张成骨中非常有效地加速骨成熟的原因，它施加静态拉伸力并缩短潜伏期。

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.