1. Departments of Biochemistry and Medicine, Queen's University, Kingston, Ontario, Canada K7L 3N6 Canada
2. Department of Chemical Pathology, The London Hospital Medical College, University of London, London El 2AD, U.K.
3. Steroids Ltd., Chicago, IL 60612, U.S.A.
4. Laboratory for the Structure of Matter, Naval Research Laboratory, Washington, DC 20375, U.S.A.,
5. Lunar Corporation, Madison, WI 53713, U.S.A.