1. Department of Cardiovascular Research, Genentech, Inc., 460 Point San Bruno Boulevard, South San Francisco, CA 94080.
2. Departments of Medicine and Microbiology, University of California, Los Angeles, CA 90024.
3. Veterans Administration, Wadsworth Medical Center, Los Angeles, CA 90073, and Departments of Medicine and Microbiology, University of California, Los Angeles, CA 90024..