STRUCTURAL BASIS OF THE INDUCTION OF UNSCHEDULED DNA-SYNTHESIS IN RATHEPATOCYTES

The structural basis of the induction of unscheduled DNA synthesis (UD S) in isolated rat hepatocytes was studied with CASE, an expert system . The analysis identified a number of structural determinants associat ed with the induction of UDS. These structures accounted for 97.3% of the activity of the chemicals in the database. Further analyses indica ted that the concordance between prediction and experimentally determi ned UDS of molecules not in the learning set is > 82%. A comparison of predictions of UDS and mutagenicity in Salmonella indicated that ther e is a dichotomy between these activities. The basis of this lack of c oincidence remains to be elucidated.