Shmakova N L, Nasonova E A, Krasavin E A, Komova O V, Mel'nikova L A, Fadeeva T A
Radiats Biol Radioecol. 2006 Jul-Aug;46(4):480-7.
The chromosome damage induced by the doses of y-irradiation 6)Co in peripheral blood lymphocytes was studied using different cytogenetic assays. Isolated lymphocytes were exposed to 0.01-1.0 Gy, stimulated by PHA, and analysed for chromosome aberrations at 48 h postirradiation by metaphase method, at 49 h--by the anaphase method, at 58 h by micronucleus assay with cytochalasin B and, additionally, micronuclei were counted at 48 h on the slides prepared for the metaphase analysis without cytochalasin B. Despite of the quantitative differences in the amount of chromosome damage revealed by different methods all of them demonstrated complex nonlinear dose dependence of the frequency of aberrant cells and aberrations. At the dose range from 0.01 Gy to 0.05-0.07 Gy the cells had the highest radiosensitivity mainly due to chromatid-type aberration induction. With dose increasing the frequency of the aberrant cells and aberrations decreased significantly (in some cases to the control level). At the doses up to 0.5-0.7 Gy the dose-effect curves have become linear with the decreased slope compare to initial one (by factor of 5 to 10 for different criteria) reflecting the higher radioresistance of cells. These data confirm the idea that the direct linear extrapolation of high dose effect to low dose range--the procedure routinelly used to estimate genetic risk of low dose irradiation--cannot be effective and may lead to underestimation of chromosome damage produced by low radiation doses. Preferences and disadvantages of used cytogenetic assays and possible mechanisms of low ionising radiation doses action were discussed.
采用不同的细胞遗传学分析方法，研究了60Coγ射线辐照剂量对外周血淋巴细胞造成的染色体损伤。分离出的淋巴细胞接受0.01 - 1.0 Gy的辐照，用植物血凝素（PHA）刺激，在辐照后48小时通过中期分析法分析染色体畸变，49小时通过后期分析法分析，58小时通过细胞松弛素B微核试验分析，此外，在未添加细胞松弛素B的用于中期分析的载玻片上于48小时计数微核。尽管不同方法所揭示的染色体损伤数量存在定量差异，但所有方法均表明异常细胞频率和畸变呈现复杂的非线性剂量依赖性。在0.01 Gy至0.05 - 0.07 Gy的剂量范围内，细胞具有最高的放射敏感性，这主要归因于染色单体型畸变的诱导。随着剂量增加，异常细胞频率和畸变显著降低（在某些情况下降至对照水平）。在高达0.5 - 0.7 Gy的剂量下，剂量效应曲线变为线性，与初始曲线相比斜率降低（不同标准下降低5至10倍），这反映了细胞更高的放射抗性。这些数据证实了这样一种观点，即将高剂量效应直接线性外推至低剂量范围——这是常规用于估计低剂量辐照遗传风险的程序——可能无效，并可能导致低估低辐射剂量产生的染色体损伤。文中讨论了所使用的细胞遗传学分析方法的优缺点以及低电离辐射剂量作用的可能机制。
