1. Department of Medicine, University of Texas Medical Branch, Galveston, Texas;
2. Department of Public Health Sciences, Wake Forest University School of Medicine, Winston-Salem, North Carolina;
3. Department of Medicine, University of Texas Health Science Center, San Antonio, Texas;
4. Department of Medicine, Baylor College of Medicine, Houston, Texas;
5. Arizona State University, Tempe, Arizona;
6. Department of Medicine, Columbia University, St. Luke's-Roosevelt Hospital, New York, New York;
7. The Methodist Hospital, Houston, Texas.