1. Department of Environmental Medicine, University of Rochester School of Medicine, Rochester 14642;
2. Cornell University Medical College, New York, New York 10021;
3. Washington University School of Medicine, St. Louis, Missouri 63110;
4. Laboratory of Pharmacology and Chemistry, NIEHS/NIH, Research Triangle Park, North Carolina 27709;
5. Department of Medicine and Liver Center, Yale University School of Medicine, New Haven, Connecticut 06520; and
6. Mount Desert Island Biological Laboratory, Salsbury Cove, Maine 04672