[Unscheduled DNA synthesis and evaluation of the effects of drugs].

Unplanned DNA synthesis (UDS) represents one of the methods for the evaluation of genetic risk due to the action of xenobiotics in the organism. UDS is a parameter enabling quantification of the process of excisional repair of DNA, which results in the regeneration of the integrity of the genetic information (i. e,. correct sequence of nucleotides in DNA) after interaction with a mutagen. If the activity of the repair enzymic systems is not sufficient, the gene expression is affected, disorders in the functions of the damaged cells and tissues occur, or the cells die. The most important result is, however, the initiation of the process of carcinogenesis. A study of UDS within the framework of testing of novel drugs would markedly contribute to reveal possible negative as well as positive effects of the drugs tested both in vitro and in vivo tests. The present paper thus discusses possible uses of UDS study within preclinical and clinical testing of novel drugs.