Matsumoto K, Ramsey M J, Nelson D O, Tucker J D
Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
Radiat Res. 1998 Jun;149(6):602-13.
We have investigated the persistence of translocations and other types of chromosome damage with time using human peripheral blood acutely exposed in vitro to 137Cs gamma rays at doses ranging from 0.5 to 4 Gy. Freshly drawn blood from one donor was irradiated and metaphase chromosomes were prepared 2 to 7 days after exposure. Chromosomes 1, 2 and 4 were painted red-orange and chromosomes 3, 5 and 6 were painted green by fluorescence in situ hybridization (FISH) using "semi-directly" labeled whole-chromosome painting probes. This type of labeling combines direct and indirect labeling and showed significant advantages over both these other methods. All types of structural chromosome aberrations were classified by the Protocol for Aberration Identification and Nomenclature Terminology (PAINT) system. The yields of dicentric chromosomes, acentric fragments and ring chromosomes diminished with time as expected. Translocations exhibited greater persistence but showed a clear and statistically significant reduction in frequency at all doses. The mathematical model suggested that the translocation frequencies would reach a plateau of approximately 4, 15, 51, 106 and 179 translocations per 100 cell equivalents after irradiation with 0.5, 1, 2, 3 and 4 Gy, respectively. When translocations were classified by the conventional system, an analysis of the distribution of translocations and dicentrics per cell indicated that both types of exchanges were Poisson-distributed 48 h postirradiation. However, cells bearing translocations have a higher possibility of having dicentrics than cells without translocations. These findings suggest that dicentrics may contribute to a decline of translocation frequencies with time, and that some translocations are not completely persistent. The results obtained here using human blood exposed in vitro may influence the use of translocations as a retrospective biodosimeter of exposure to ionizing radiation in humans.
我们使用体外急性暴露于剂量范围为0.5至4 Gy的137Csγ射线的人外周血，研究了易位及其他类型染色体损伤随时间的持续性。从一名供体采集的新鲜血液经照射后，在暴露后2至7天制备中期染色体。使用“半直接”标记的全染色体涂染探针，通过荧光原位杂交（FISH）将1号、2号和4号染色体涂染为红橙色，3号、5号和6号染色体涂染为绿色。这种标记类型结合了直接标记和间接标记，相较于其他两种方法显示出显著优势。所有类型的结构染色体畸变均按照畸变识别与命名术语协议（PAINT）系统进行分类。正如预期的那样，双着丝粒染色体、无着丝粒片段和环状染色体的产率随时间下降。易位表现出更高的持续性，但在所有剂量下频率均有明显且具有统计学意义的降低。数学模型表明，分别用0.5、1、2、3和4 Gy照射后，每100个细胞当量的易位频率将分别达到约4、15、51、106和179次易位的平台期。当按照传统系统对易位进行分类时，对每个细胞中易位和双着丝粒分布的分析表明，两种类型的交换在照射后48小时呈泊松分布。然而，携带易位的细胞比不携带易位的细胞更有可能具有双着丝粒。这些发现表明，双着丝粒可能导致易位频率随时间下降，并且一些易位并非完全持久。此处使用体外暴露的人血获得的结果可能会影响将易位用作人类电离辐射暴露回顾性生物剂量计的应用。
