Induction of the adaptive response by X-rays is dependent on radiation intensity.
Induction of the adaptive response by X-rays is dependent on radiation intensity.
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X 射线引起的适应性响应取决于辐射强度。
DOI：
10.1080/09553008914551231
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发表时间：
1989
影响因子：
2.6
通讯作者：
Wiencke,JK
中科院分区：
文献类型：
--
作者：
Shadley,JD;Wiencke,JK
用低剂量（0·01戈伊）但不高剂量（0·5戈伊）X射线预处理的人淋巴细胞，在一定程度上对随后暴露于高剂量（1·5戈伊）X射线诱导的染色单体缺失具有抗性（即染色单体缺失的产量小于预暴露和随后激发剂量诱导的产量之和）。这种适应性反应也可以通过用非常低或甚至高浓度的氚化胸苷预处理细胞来诱导。由于高浓度的氚化胸苷导致以非常低的剂量率（即<0·01戈伊/min）递送的高剂量辐射，因此在高预处理剂量的X射线之后缺乏适应可能归因于其较高的剂量率。为检测X射线强度对诱导适应性反应的影响，在培养28-30 h时用0·5戈伊的X射线以0·005-0·5戈伊/min照射淋巴细胞，然后在48 h时用1·5戈伊照射淋巴细胞。6 h后测定染色单体缺失。结果表明，低剂量率（0·005或0·01戈伊/min）照射0·5戈伊能诱发适应性反应，而高剂量率（0·1、0·2或0·5戈伊/min）照射则不能诱发适应性反应。此外，将暴露于以0·005戈伊/min给予的0·5戈伊的男性受试者的细胞与以0·5戈伊/min照射的0·5戈伊的女性受试者的细胞共培养的实验显示，暴露于低强度和高强度辐射的细胞同等地进展到中期，因此，在高剂量率下缺乏适应性反应不能归因于抗辐射细胞的选择。尽管在低辐射强度下，在较高X射线剂量下诱导适应性反应，但这种效应似乎需要一个最小剂量;例如，0·01-戈伊预处理诱导适应性反应时，在0·2戈伊/min，但不是在0·005戈伊/min。
Human lymphocytes pretreated with low (0·01 Gy) but not high (0·5 Gy) doses of X-rays become somewhat refractory to the induction of chromatid deletions by subsequent exposure to high (1·5 Gy) doses of X-rays (i.e. the yield of chromatid deletions is less than the sum of the yields induced by the pre-exposure and the subsequent challenge doses). This adaptive response can also be induced by pretreating the cells with very low, or even high, concentrations of tritiated thymidine. Because high concentrations of tritiated thymidine result in high doses of radiation that are delivered at very low dose-rates (i.e. <0·01 Gy/min), the lack of adaptation following high pre-treatment doses of X-rays could be attributed to their higher dose-rates. To test the effect of X-ray intensity on the induction of the adaptive response, lymphocytes were irradiated with 0·5 Gy of X-rays at 0·005–0·5 Gy/min at 28–30 h of culture, and then irradiated with 1·5 Gy at 48 h. Chromatid deletions were measured 6 h later. The results show that 0·5 Gy of X-rays given at low dose-rates (0·005 or 0·01 Gy/min), but not at high dose-rates (0·1, 0·2, or 0·5 Gy/min), are capable of inducing the adaptive response. Furthermore, experiments in which a male subject's cells exposed to 0·5 Gy given at 0·005 Gy/min were cocultivated with a female subject's cells irradiated with 0·5 Gy at 0·5 Gy/min showed that cells exposed to radiation at low and high intensity progress to metaphase equally and, therefore, that the lack of an adaptive response at high dose-rates cannot be attributed to selection of radioresistant cells. Although the induction of the adaptive response at higher X-ray doses occurs at low radiation intensity, there seems to be a minimum dose required for this effect; e.g., 0·01-Gy pretreatments induced the adaptive response when given at 0·2 Gy/min, but not at 0·005 Gy/min. Thus, the adaptive response is dependent both on the total dose of the pretreatment and on the rate at which the dose is given.