Effects of ultraviolet light and cyclophosphamide on replication and repair synthesis of DNA in isolated rat liver cells and human leukocytes co-incubated with microsomes

Algorithm of Molecular and Biological Assessment of the Mechanisms of Sensitivity to Drug Toxicity by the Example of Cyclophosphamide

Comparative study of the liver, blood, and spleen of DBA/2JSto and BALB/cJLacSto mice sensitive and resistant to acute toxicity of the cyclophosphamide allowed us to reveal basic toxicity biomarkers of this antitumor and immunosuppressive agent. Obtained results can be used for the development of an algorithm for evaluation of toxic effects of drugs and food components.

Evaluation of experimental parameters in an S9 /human leukocyte SCE test with cyclophosphamide

The experimental parameters S9 concentration, cofactor concentration and exposure time were investigated in a microsome test with human leukocyte cultures, To evaluate these parameters, their effects on cyclophosphamide-induced SCE frequencies and changes in cell proliferation were analyzed. By varying S9 concentration and exposure time, dose-effect relationships were found with respect to the induction of SCE. A relatively small effect was found when the concentrations of the cofactors NADP and G-6-P were varied. In general, an increase in SCE frequencies was accompanied by delayed cell proliferation. The importance of varying the experimental parameters to avoid false- negative results in microsome tests is discussed.

Methods for analysis of the mutagenicity of indirect mutagens/carcinogens in eukaryotic cells

The review discusses the variety of methods for activation of indirect mutagens/carcinogens and testing them in cell cultures, especially in mammalian cell cultures. After the necessity for including metabolizing components in mutagenicity tests has been pointed out, the enzymes that transform foreign compounds metabolically, and the factors influencing them, are described. In the main section the various methods of activating indirect mutagens/carcinogens are presented. The methods of including in vivo metabolism in mutagenicity tests are: Analysis of cells from organisms contaminated with a chemical (III.l.a); body fluid-mediated mutagenesis (III.l.b); host-mediated assay (III.l.c). The following activation systems are suitable for including in vitro metabolism of test compounds in mutagenicity tests: Liver and lung perfusion (III.2.a.alpha); organ slices and homogenates (III.2.a.beta); subcellular fractions (III.2.a.gamma); cultivated cells (cell-mediated mutagenesis) (III.2.b); nonenzymatic activation systems (III.2.c). Finally the main factors that influence the metabolism of test substances are summarized. Two factors illustrate the mutagenicity tests with regard to the metabolism of mammalian livers and the methods of performing mutagenicity tests in man.