Liu B C, Harrell R, Davis R H, Dresden M H, Spira M
Institute of Occupational Medicine, Chinese Academy of Preventive Medicine, Beijing.
J Biomed Mater Res. 1989 Aug;23(8):833-44. doi: 10.1002/jbm.820230803.
The effect of gamma irradiation on the physicochemical properties of injectable human amnion collagen was investigated. Pepsin-extracted human amnion collagen was purified, reconstituted, and irradiated with varying doses of gamma irradiation (0.25 Mrads to 2.5 Mrads). Gamma irradiation had a significant impact on the physical characteristics of the collagen. The neutral solubility of collagen in PBS at 45 degrees C was decreased from 100% for the nonirradiated control sample to 16% for the 2.5 Mrads irradiated sample. SDS polyacrylamide gel electrophoresis also demonstrated the dose-dependent effect of gamma irradiation on collagen cross-links. Electron microscopic observation revealed that even at low irradiation dose (0.25 Mrads), collagen fibril diameter increased. The average diameter was 50 nm for nonirradiated control fibrils, while 4.4 percent of the irradiated collagen fibrils had a diameter greater than 100 nm. Irradiated collagen showed little evidence of damage. Well-preserved cross-striations were found in collagen fibrils at all doses of irradiation. Native amnion collagen irradiated with gamma rays demonstrated a slight increase in resistance to collagenase degradation compared with nonirradiated native collagen samples. Increased resistance to collagenase did not correlate with increasing irradiation dose. After 30 min of incubation at 37 degrees C, both irradiated and nonirradiated collagen was completely digested by collagenase. However, gamma-irradiated collagen did become more sensitive to hydrolysis by trypsin. The higher the irradiation doses used, the greater sensitivity to trypsin was observed. At 0.25 Mrads irradiation only a slight increase was found. No marked differences in amino acid composition were noted among the high dose irradiated, low dose irradiated and control amnion collagen.
研究了γ射线辐照对可注射人羊膜胶原蛋白理化性质的影响。用胃蛋白酶提取人羊膜胶原蛋白，进行纯化、复溶，并用不同剂量的γ射线辐照（0.25兆拉德至2.5兆拉德）。γ射线辐照对胶原蛋白的物理特性有显著影响。胶原蛋白在45℃下于PBS中的中性溶解度从未辐照对照样品的100%降至2.5兆拉德辐照样品的16%。SDS聚丙烯酰胺凝胶电泳也证明了γ射线辐照对胶原蛋白交联的剂量依赖性效应。电子显微镜观察显示，即使在低辐照剂量（0.25兆拉德）下，胶原纤维直径也会增加。未辐照对照纤维的平均直径为50纳米，而4.4%的辐照胶原纤维直径大于100纳米。辐照后的胶原蛋白几乎没有损伤迹象。在所有辐照剂量下的胶原纤维中均发现了保存完好的横纹。与未辐照的天然胶原蛋白样品相比，经γ射线辐照的天然羊膜胶原蛋白对胶原酶降解的抗性略有增加。对胶原酶抗性的增加与辐照剂量的增加无关。在37℃孵育30分钟后，辐照和未辐照的胶原蛋白均被胶原酶完全消化。然而，γ射线辐照的胶原蛋白对胰蛋白酶水解变得更敏感。所用辐照剂量越高，则观察到对胰蛋白酶的敏感性越高。在0.25兆拉德辐照时仅发现略有增加。高剂量辐照、低剂量辐照和对照羊膜胶原蛋白之间在氨基酸组成上未发现明显差异。
