The shape of dose-survival curves for mammalian cells and repair of potentially lethal damage analyzed by hypertonic treatment.
The shape of dose-survival curves for mammalian cells and repair of potentially lethal damage analyzed by hypertonic treatment.
复制标题
通过高渗治疗分析哺乳动物细胞的剂量生存曲线的形状和潜在致命损伤的修复。
作者：
W. Pohlit;I. R. Heyder
在通过集落形成能力测试细胞存活的通常程序中，发生潜在致死性损伤（PLD）的修复。通过在高渗悬浮液中孵育细胞，可以抑制这种修复的某一部分，导致如细胞中致死事件的泊松分布所预期的指数剂量-存活曲线。如果这样的高渗治疗是在X射线照射后增加间隔后进行的，则获得肩部长度增加的曲线。这种修复的动力学的定量分析表明，PLD被修复约1小时后，照射由饱和的修复系统，消除约一个损伤每15分钟每个细胞独立的所施加的吸收剂量。PLD没有消除这最后一个系统是由一个不饱和的系统修复的时间常数为几个小时。PLD的修复后，X射线照射的收益定量以这种方式在平台期细胞悬浮在条件培养基，这似乎是最佳的这种修复。如果这些细胞在照射后悬浮在正常的营养培养基中，则一定比例的PLD转化为不可修复的损伤。在营养培养基中修复后的最终存活率与通过在营养琼脂上通常测量菌落形成能力获得的存活率相同。这表明，平台期细胞剂量-存活曲线中的肩部部分是由于PLD的修复，部分是由于这种损伤在修复期间的表现。«少
During the usual procedure of testing cell survival by colony-forming ability, repair of potentially lethal damage (PLD) takes place. By incubating the cells in hypertonic suspension a certain part of this repair can be inhibited, leading to an exponential dose-survival curve as expected from the Poisson distribution of lethal events in the cells. If such a hypertonic treatment is performed after increasing intervals following irradiation with x rays, curves with increasing shoulder length are obtained. Quantitative analysis of the kinetics of this repair shows that PLD is repaired for about 1 h after irradiation by a saturated repair system which eliminates about one lesion per 15 min per cell independent of the applied absorbed dose. PLD not eliminated by this last system is repaired by an unsaturated system with a time constant of several hours. Repair of PLD after x irradiation proceeds quantitatively in this way in plateau-phase cells suspended in a conditioned medium, which seems optimal for such repair. If these cells are suspended after irradiation in normal nutrient medium a certain fraction of the PLD is transformed into irreparable damage. The final survival after repair in nutrient medium is then identical with that obtained by the usual measurementmore » of colony-forming ability on nutrient agar. This indicates that the shoulder in dose-survival curves for plateau phase cells ispartly due to repair of PLD and partly due to manifestation of this damage during repair time.« less