1. Sansum Medical Research Foundation, Santa Barbara, CA 93111
2. Chemistry Department, University of California, Santa Barbara, CA 93106
3. School of Medicine, University of Missouri, Columbia, MO 65212
4. National Heart, Lung, and Blood Institute/National Institutes of Health, Division of Blood Diseases and Resources, 6701 Rockledge Dr., 10th floor, Room 10158, Bethesda, MD 20817