1. Formerly with the Department of Clinical Bioethics, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Mayland 20892.
2. Department of Clinical Bioethics, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland 20892.
3. University of Minnesota, School of Public Health, Division of Biostatistics, Minneapolis, Minnesota 55455.
4. National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892.