Microbiomechanical studies on biological tissue/cell interaction and remodeling

1.生长、成熟、血压和血流变化对血管壁重塑的影响取8 ~ 64周龄Wistar大鼠颈总动脉进行生物力学、形态学和组织学研究。血流、压力、壁厚、壁周向弹性模量随年龄增大而增大；然而，结缔组织的组成保持不变。doca -盐高压使壁厚增加，使壁应力保持恒定，弹性模量和血管收缩力增加，同时平滑肌细胞肥大。静脉壁也有类似现象。高血压患者血流变化不影响壁面剪切应力。这些变化与结缔组织成分的变化无关。胶原交联与衰老、高血压引起的血管壁力学性能变化有一定关系。在兔成熟膝关节上制造宽度为髌腱宽度1/3的矩形缺损，采用应力屏蔽技术去除愈合过程中的应力。应力剥夺极大地抑制和延缓了缺损处再生组织强度的增加，同时也显著降低了缺损处残余组织的强度。应力屏蔽后的应激迅速增加了两种组织的强度，尽管即使在很长一段时间后也没有恢复到正常水平，这意味着应力屏蔽对愈合组织有非常不利的影响。研究了生长因子对组织愈合和胶原束力学性能的影响。活动度变化对松质骨结构和力学性能的影响固定化后松质骨的数量和硬度明显降低；虽然花了很长时间，但他们被重新安置。体育锻炼可提高松质骨和皮质骨的硬度，而停止体育锻炼可使松质骨的硬度更快地恢复正常。细胞力学性能研究开发了测定细胞力学性能的新技术。少

1.Effects of Growth, Maturation, and Blood Pressure and Flow Change on Vascular Wall RemodelingCommon carotid arteries harvested from Wistar rats aged 8 to 64 weeks were used for biomechanical, morphological, and histological studies. Blood flow, pressure, wall thickness, and wall circumferential elastic modulus increased with age ; however, the composition of connective tissues remained unchanged. DOCA-salt hypertension increased wall thickness so as to maintain wall stress at constant, and increased elastic modulus and vascular contractility being accompanied with smooth muscle cell hypertrophy. Similar phenomena were also observed in venous wall. Blood flow changes under hypertension did not affect wall shear stress. These changes did not correlate with the changes in connective tissue composition. Collagen cross-linking has some relation with the changes of wall mechanical properties induced by aging and hypertension.2.Effects of Growth and Maturation, and Stress Deprivation and Re … More stressing on the Mechanical Properties of Healing Patellar TendonsA rectangular defect having the width of 1/3 of the width of the patellar tendon was made in the mature rabbit knee, and then a stress shielding technique was applied to the tendon for removing stress during healing. Stress deprivation greatly suppressed and delayed the increase of strength of the tissue regenerated in the defect and also markedly reduced the strength of the residual tissue. Restressing after stress shielding rapidly increased the strength of both tissues, although iit was not recovered to normal level even after a prolonged period of time, implying that stress shielding gives very adverse effects on healing tissues. Effects of growth factors on tissue healing and mechanical properties of collagen fascicles were also studied.3.Effects of Activity Changes on the Structure and Mechanical Properties of Cancellous BoneThe amount and hardness of cancellous bone were significantly reduced by immobilization ; they were recovered by remobilization, although it took much time. Physical exercise increased the hardness of cancellous and cortical bone, and its quitting returned the hardness to normal more quickly in cancellous bone.4.Mechanical Properties of CellsNew techniques were developed for the determination of the mechanical properties of cells. Less