端粒是位于真核细胞染色体末端的DNA-蛋白质复合体,在维持染色体稳定上起着重要的作用,并且与细胞的衰老、癌变有着密切的关系。本实验观察了DNA依赖性蛋白激酶(DNA-dependent protein kinase,DNA-PK)抑制剂-渥曼青霉素(wortmannin,WM)对H2O2诱导的HeLa细胞端粒DNA链断裂重连接效应。结果表明WM能够显著地抑制H2O2诱导的HeLa细胞端粒DNA链断裂后的重连接作用,提示DNA-PK参与了端粒DNA链断裂损伤的修复过程。
Blood ketone body level and ketone body ratio (acetoacetate/β hydroxybutyrate) are commonly used as clinical diagnostic indices.But there is no systematic study on the variability of these indices in the blood circulation.We investigated the concentration of ketone bodies within different segments of the circulation in fed ad libitum rats, starved rats and alloxan induced diabetic rats.Blood samples were drawn from femoral artery, suprarenal inferior vena cava and hepatic vein of each rat, respectively.The concentrations of acetoacetate and β hydroxybutyrate were measured by enzymatic method.To avoid mixing of the blood streams, appropriate strangulation of the vessels was taken when sampling.The total ketone body level was always the highest in the hepatic vein, secondary in the femoral artery and the lowest in the suprarenal vena cava in rats in different states.But surprisingly, the concentration of acetoacetate was the lowest in the hepatic vein and the highest in the femoral artery.The ketone body levels elevated in both starvation and diabetes, and the ketone body ratios were changed in the circulation.While blood flows through extra hepatic tissues, the total concentration of ketone body is undergoing degression, but the concentration of acetoacetate could be elevated due to the conversion of ketone body in extra hepatic tissues.Therefore, ketone body ratio is changeable in different segments of the blood circulation, including that between hepatic vein and artery.The correlation of ketone body ratio between arterial and hepatic venous blood could be effected by different pathophysiological states, such as starvation and diabetes.The “Redox theory” deserves a further discussion.
