1. Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama.
2. Department of Epidemiology, and University of Alabama at Birmingham, Birmingham, Alabama.
3. Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama.
4. Department of Health Behavior and Education, University of Connecticut, Storrs, Connecticut.
5. Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland.
6. Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
7. Department of Medicine, University of Washington, Seattle, Washington.