1. Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California.
2. Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California.
3. Department of Medicine, Cook County Hospital, Chicago, Illinois.
4. Department of Medicine, Montefiore Medical Center, Bronx, New York.
5. Department of Medicine, Georgetown University, Washington, D.C.