Osteoarthritis of the TMJ and Mechanical Stress

过度的机械应力被认为是导致关节软骨破裂的原因。为了研究机械应力对软骨细胞代谢的影响，我们检测了细胞外基质合成以及软骨降解因子和生长因子的基因表达。1.15 kPa循环机械应力（CTF）对蛋白多糖（PG）合成的影响小于5 kPa(5和15 kPa时分别增加230.3和179.1%)，2.5 kPa循环机械应力（CTF）对DNA合成的影响大于5 kPa（5和15 kPa时分别减少50.0和30.1%）。在两种ctf水平下，相对于相应对照的平均归一化il -1 β mRNA水平均短暂升高。在CTF为15 kPa时，相对于相应对照的平均归一化bFGF mRNA水平短暂升高，而在CTF为5 kPa时则无显著变化。在CTF作用15 kPa时，MMP-9相对于相应对照的平均归一化mRNA水平逐渐升高，而在CTF作用5 kPa时，MMP-9相对于相应对照的平均归一化mRNA水平短暂升高。平均归一化MMP-2、TIMP-1、agrecan、collagen type II和X型mRNA水平在ctf水平上与对照组相比无显著变化。施加15 kPa CTF时，亲MMP-9的产生水平没有变化，但活性形态的MMP-9水平略有增加，而施加5 kPa CTF时，亲MMP-9的产生水平没有明显变化，也没有被激活为活性形态的MMP-9。两种水平的CTF均未改变MMP-2的产生。

Excessive mechanical stress has been proposed as a cause breakdown of the articular cartilage. To investigate the effect of mechanical stress on chondrocyte metabolism, we examined the extracellular matrix synthesis and the gene expression of cartilage degradation factors and growth factors.1.15 kPa cyclic mechanical stress (CTF) caused less increase in proteoglycan (PG) synthesis than 5 kPa (230.3 and 179.1% increase at 5 and 15 kPa)2.5 kPa of CTF caused more decrease in DNA synthesis (50.0 and 30.1% decrease, at 5 and 15 kPa).3.The mean normalized IL-1beta mRNA level against the corresponding control transiently increased during both level of CTF.4.The mean normalized bFGF mRNA level against the corresponding control transiently increased during 15 kPa of CTF,while remarkable change was not observed at 5 kPa of CTF.5.The mean normalized MMP-9 mRNA level against the corresponding control progressively increased during 15 kPa of CTF,while the transient increase was observed during 5 kPa of CTF.6.Mean normalized MMP-2, TIMP-1, agrecan, collagen type II and type X mRNA level against the control did not show remarkable change at the both level of CTF.7.When 15 kPa of CTF was applied, the production level of pro-MMP-9 did not change, but the level of active form MMP-9 was slightly increased, while 5 kPa of CTF was applied, the production level of pro-MMP-9 did not show remarkable change and it was not activated to active form MMP-9. Both level of CTF did not change the production of MMP-2.