1. Division of Gastroenterology, Washington University School of Medicine, St. Louis, MO, USA
2. Division of Gastroenterology, Duke University School of Medicine and the Durham VA Medical Center, Durham, NC, USA
3. Division of Gastroenterology, The First Hospital of Jilin University, Changchung, Jilin, China
4. Division of Gastroenterology, John Cochran VA Medical Center Saint Louis, MO, USA