Lorenz R, Deubel W, Leuner K, Göllner T, Hochhäuser E, Hempel K
Institut für Medizinische Strahlenkunde und Zellforschung der Universität Würzburg, Germany.
Int J Radiat Biol. 1994 Sep;66(3):319-26. doi: 10.1080/09553009414551251.
The frequency of hypoxanthine phosphoribosyl transferase (HPRT) deficient splenic T lymphocytes was measured in the 137Cs gamma-irradiated mouse by the T cell cloning method. Doses from 0.3 to 6 Gy were applied at the dose-rates 0.5 Gy/min, 1 Gy/day and 1 Gy/week. Mutants were determined 8-10 and 30-40 weeks after the end of exposure. Radiation-induced mutant frequency (MFi) was calculated by subtracting the age corrected spontaneous mutant frequency (MFsp) from total mutant frequency (MF) found in irradiated animals. Data were fitted to linear and linear-quadratic dose-response models. MFi depended markedly on dose, dose-rate and time after exposure. When mutants were determined 8-10 weeks after acute irradiation (0.5 Gy/min) the dose-effect curve fitted the linear-quadratic equation MFi = 6.9 x 10(-6) Gy + 1.2 x 10(-6) Gy2, whereas in low dose-rate experiments (1 Gy/day, 1 Gy/week) the dose-effect curves were linear. The slope of the linear regression was about 3 x 10(-6). When low dose-rate-irradiated animals were killed 30-40 weeks after irradiation, MFi was about one-third of that observed after 8 weeks. The dose dose-rate effectiveness factor (DDREF) for radiation mutagenicity was calculated in animals that had been exposed 8-10 weeks previously. For doses < 2 Gy the reduction in effectiveness was about 1.5 when the irradiation dose-rate was < or = 1 Gy/day. For higher doses DDREF was 3-5.
通过T细胞克隆法测定了137Csγ射线辐照小鼠中次黄嘌呤磷酸核糖基转移酶（HPRT）缺陷型脾T淋巴细胞的频率。以0.5 Gy/min、1 Gy/天和1 Gy/周的剂量率施加0.3至6 Gy的剂量。在照射结束后8 - 10周和30 - 40周测定突变体。通过从辐照动物中发现的总突变频率（MF）中减去年龄校正后的自发突变频率（MFsp）来计算辐射诱导的突变频率（MFi）。数据拟合到线性和线性二次剂量反应模型。MFi明显取决于剂量、剂量率和照射后的时间。当在急性照射（0.5 Gy/min）后8 - 10周测定突变体时，剂量效应曲线符合线性二次方程MFi = 6.9×10（-6）Gy + 1.2×10（-6）Gy2，而在低剂量率实验（1 Gy/天，1 Gy/周）中，剂量效应曲线是线性的。线性回归的斜率约为3×10（-6）。当低剂量率辐照的动物在照射后30 - 40周处死时，MFi约为8周后观察到的值的三分之一。在8 - 10周前接受照射的动物中计算了辐射致突变性的剂量剂量率有效性因子（DDREF）。对于<2 Gy的剂量，当照射剂量率≤1 Gy/天时，有效性降低约1.5。对于更高的剂量，DDREF为3 - 5。
