Cronkite E P, Inoue T, Bullis J E
Medical Department, Brookhaven National Laboratory, Upton, New York 11973.
Radiat Res. 1994 May;138(2):266-71.
C57Bl/6 mice were given 10 Gy X rays fractionated in several ways. There was a cyclical pattern of animal survival which was correlated to the fractionation interval and which indicated a periodicity of 6 h. Ten grays given in a single dose is fatal to 100% of the mice and depresses the CFU-S to about one per leg with no evidence of proliferation during the remaining life. Ten grays given in 2.5-Gy increments at 24-h intervals causes no fatalities and results in a similar CFU-S depression but is followed by an exponential increase in CFU-S over the ensuing 12 days. Although bone marrow from survivors of such treatment was comparable to control marrow in its capacity for short-term rescue, it was clearly inferior in its capacity for long-term rescue. The periodicity of 6 h suggests that the cells responsible for survival of the mice have been synchronized into more or less radiosensitive and radioresistant stages of the cell cycle as a result of the time between the 2.5-Gy increments. Implications for the CFU-S and long-term repopulating cells are discussed.
将C57Bl/6小鼠以几种方式给予10 Gy的X射线分次照射。动物存活呈现出一种周期性模式，该模式与分次照射间隔相关，表明存在6小时的周期性。单次给予10 Gy对100%的小鼠是致命的，会使脾集落形成单位（CFU-S）降至每条腿约1个，且在剩余生命期内无增殖迹象。以2.5 Gy的增量、每隔24小时给予10 Gy不会导致死亡，会使CFU-S出现类似程度的降低，但随后在接下来的12天内CFU-S呈指数增长。尽管经此类处理的存活小鼠的骨髓在短期救援能力方面与对照骨髓相当，但其长期救援能力明显较差。6小时的周期性表明，由于2.5 Gy增量之间的时间间隔，负责小鼠存活的细胞已同步进入细胞周期中或多或少的放射敏感和放射抗性阶段。文中讨论了对CFU-S和长期再增殖细胞的影响。
