MODELING THE AMES TEST
MODELING THE AMES TEST
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DOI：
10.1016/0165-1161(81)90282-x
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发表时间：
1981-01-01
期刊：
影响因子：
--
通讯作者：
CLAXTON, L
中科院分区：
文献类型：
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作者：
STEAD, AG;HASSELBLAD, V;CLAXTON, L
尽管艾姆斯试验[使用鼠伤寒沙门氏菌]的价值和广泛使用，但很少有人关注分析这些数据的标准化定量方法。开发了一个现实且统计上易于处理的模型来评估Ames类型数据。该模型假设任何剂量下的回复突变菌落形成遵循泊松过程，而每个平板的回复突变体平均数是最多4个参数的非线性函数。指数衰减项可以包括在模型中以调整毒性。使用修改的高斯-牛顿迭代法求解得到的非线性方程组，以获得模型参数的最大似然估计。通过拟合简化模型和使用似然比检验来检验关键参数的显著性。该模型的性能证明从各种环境污染物的有机提取物的数据。所提出的模型的优点之一是在参数估计过程中没有数据被丢弃，没有任意常数需要添加到零计数或剂量，并且不需要数据的数学变换。
Despite the value and widespread use of the Ames test [which uses Salmonella typhimurium], little attention has been focused on standardizing quantitative methods of analyzing these data. A realistic and statistically tractable model is developed for the evaluation of Ames-type data. The model assumes revertant colony formation at any dose follows a Poisson process, while the mean number of revertants per plate is a nonlinear function of up to 4 parameters. An exponential decay term can be included in the model to adjust for toxicity. The resultant system of nonlinear equations is solved using a modified Gauss-Newton iterative scheme to obtain maximum likehood estimates of the model parameters. Significance of the key parameters is tested by fitting reduced models and using likelihood ratio tests. The model''s performance is demonstrated on data from organic extracts of various environmental contaminants. Among the advantages of the proposed model are no data is discarded in the parameter estimation process, no arbitrary constants need to be added to zero counts or doses and no mathematical transformation of the data is required.