1. University of California, Davis Medical Center, Sacramento, California 95817
2. Harvard School of Public Health, Cambridge, Massachusetts 02115
3. University of California, San Diego, California 92103
4. Washington University School of Medicine, St. Louis, Missouri 63110
5. Division of AIDS, National Institutes of Health, Bethesda, Maryland 20892
6. University of California, San Diego, California 92103, and San Diego VA Medical Center, San Diego, California 92103
7. Yale School of Medicine, New Haven, Connecticut 06510