Phenomenon and mechanism of "secondary damage" during repair of DNA damage in irradiated mammalian cells

By means of comet assay, a study of kinetics curve of DNA damage repair in irradiated SX-9 cells that came from mouse breast cancer proceeded. It was found that while the initial DNA damages had nearly been repaired, DNA damages arose for the second time, then they were repaired again. As a result, a phenomenon of "secondary damage" was found during the repair of DNA damages in irradiated SX-9 cells. Further research illuminated that 3-aminobenzamide (3AB), which is an inhibitor of poly (ADP-ribose) polymerase, could change the proceeding of "secondary damage". For this reason it is possible that there exists some inner relationship between the phenomenon of "secondary damage" and the function of poly(ADP-ribose) polymerase.

内质网应激蛋白在运动大鼠骨骼肌损伤中的表达变化

目的:研究内质网应激蛋白在运动大鼠骨骼肌损伤中的表达并探讨内质网应激在运动骨骼肌损伤中的保护作用。方法:雄性SD大鼠随机分成安静对照组(C)和单纯运动组(E),单纯运动组再平均分为运动即刻组(E1)、运动后24 h组(E2)、运动后48 h组(E3)和运动后6 d组(E4),每组8只,采用离心力竭运动为运动模式,实验后分别测定骨骼肌内质网应激蛋白表达以及血清中反应损伤特征的活性酶和抗氧化酶活性的变化。结果:运动后E1组SOD活性最高,与安静组相比并呈显著性差异(P<0.05);E2和E3组的SOD活性比安静时要低,其中与E2组呈显著性差异(P<0.05);运动后E2组MDA浓度最高,与安静对照组C比较,非常显著性差异(P<0.01),运动后E3组MDA浓度比E1、E2组低,并与E2组呈显著差异(P<0.05);血清CK、LDH在运动后24 h后达到峰值,其中E3组血清CK和LDH活性同安静对照组C比较,呈显著性差异(P<0.05),E1、E2组血清CK和LDH活性同安静对照组C比较,呈非常显著性(P<0.01);运动后E1、E2组骨骼肌中Grp78的表达的显著上升。结论:大鼠离心力竭运动后大鼠骨骼肌发生损伤,运动后骨骼肌内质网应激蛋白的发生是骨骼肌内质网应激一种体现,体现了对骨骼肌的保护。