Metting N F, Braby L A, Roesch W C, Nelson J M
Radiat Res. 1985 Aug;103(2):204-18.
Survival based on colony formation was measured for starved plateau-phase Chinese hamster ovary (CHO) cells exposed to 250 kVp X rays at dose rates of 0.0031, 0.025, 0.18, 0.31, and 1.00 Gy/min. A large dose-rate effect was demonstrated. Delayed plating experiments and dose response experiments following a conditioning dose, both using a dose rate of 1.00 Gy/min and plating delays of up to 48 hr, were also used to investigate the alternative repair hypotheses. There is clearly a greater change in survival in dose-rate experiments than in the other experiments. Thus we believe that a process which depends on the square of the concentration of initial damage, and which alters the effect of initial damage on cell survival is being observed. We have applied the damage accumulation model to separate the single-event damage from this concentration-dependent form and estimate the repair rate for the latter type to be 70 min for our CHO cells. Use of this analysis on other published dose-rate studies also yields results consistent with this interpretation of the repair mechanisms.
对处于饥饿平台期的中国仓鼠卵巢（CHO）细胞进行基于集落形成的存活测定，这些细胞暴露于剂量率为0.0031、0.025、0.18、0.31和1.00 Gy/min的250 kVp X射线下。结果显示出显著的剂量率效应。还进行了延迟接种实验以及在预处理剂量后的剂量反应实验，两者均使用1.00 Gy/min的剂量率且接种延迟长达48小时，以研究其他修复假说。显然，剂量率实验中的存活变化比其他实验中的更大。因此，我们认为正在观察到一个依赖于初始损伤浓度平方且改变初始损伤对细胞存活影响的过程。我们应用损伤累积模型将单事件损伤与这种浓度依赖性形式分离，并估计我们的CHO细胞中后一种类型的修复率为70分钟。对其他已发表的剂量率研究进行此分析也得出与这种修复机制解释一致的结果。
