1. a Division of Occupational and Environmental Medicine, University of California—San Francisco
2. b Cardiovascular Research Institute, University of California—San Francisco, Box 0924, San Francisco, CA 94143-0924
3. c Division of Occupational and Environmental Medicine, University of California—San Francisco and The Cardiovascular Research Institute, University of California—San Francisco, Box 0924, San Francisco, CA 94143-0924