ey are exposed. For example, Scholz et al. (1994) found that Chinese hamster cells irradiated in G1 were generally delayed approximately 2 hours. This stood in marked contrast to cells irradiated in the S phase. These were typically blocked for as long as 4 hours. Cells which were exposed during late G2/M suffered 4.5 hour delays (15:59-74).
Alternatively, sometimes radiation can have unpredictable effects on cells. Macklis et al. (1993) analyzed two different types of lymphoma cells in order to determine whether or not G2/M cells were delayed after irradiation. The investigators exposed both EL-4 and Raji cells to high-dose-rate and low-dose-rate gamma irradiation. While approximately 5.7 percent of unirradiated EL-4 cells occurred in the G2/M phase, that proportion increased to 26.4 percent following 100-500 cGy of high-dose-rate gamma and 90Y radiation exposure. Moreover, the increase in the number of cells in G2/M was shown to be dose-dependent. Unfortunately though, while low-dose-rate 90Y irradiation did increase the numbers of EL-4 cells i
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