1. a Division of Behavioral Sciences, School of Dentistry , University of California , San Francisco
2. b Division of HIV Services, Alameda County Medical Center , Highland Hospital , Oakland
3. c Department of Family Health Care Nursing, School of Nursing , University of California , San Francisco
4. d EPI Center, Divisions of Infectious Diseases and AIDS & Oncology, San Francisco General Hospital , University of California , San Francisco , USA