1. Département de Chimie-Biologie, Université du Québec à Trois-Rivières, C. P. 500, Trois-Rivières (Québec), G9A 5H7 Canada, and Department of Medicine and Environmental and Occupational Medicine, and the Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick, New Jersey 08903