1. Department of Gastroenterology, The 980th Hospital of the People's Liberation Army Joint Service (Bethune International Peace Hospital), Shijiazhuang, Hebei 050082, P.R. China
2. Department of Gastroenterology, The 980th Hospital of the People's Liberation Army Joint Service (Bethune International Peace Hospital), Shijiazhuang, Hebei 050082, P.R. China
3. Outpatient Department, The Xicheng 4th Rest Center for Retired Cadres of Beijing Garrison Area of the People's Liberation Army, Beijing 100032, P.R. China
4. Department of Clinical Laboratory, The 980th Hospital of the People's Liberation Army Joint Service (Bethune International Peace Hospital), Shijiazhuang, Hebei 050082, P.R. China