1. Gastroenterology and Hepatology Service, Wilford Hall Medical Center, San Antonio, Texas, USA
2. Department of Medicine, Wilford Hall Medical Center, San Antonio, Texas, USA
3. Gastroeneterology and Hepatology Service, Wilford Hall Medical Center, San Antonio, Texas, USA
4. Division of Gastroenterology and Hepatology, Department of Medicine, Brooke Army Medical Center, Fort Sam Houston, San Antonio, TX 78234, USA