1. Health Service Center; Hiroshima University; Higashihiroshima Japan
2. Department of Endoscopy; University Medical Center; Ho Chi Minh Vietnam
3. Department of Gastroenterology; Gia-Dinh People's Hospital; Ho Chi Minh Vietnam
4. Faculty of Human Culture and Science; Prefectural University of Hiroshima; Hiroshima Japan
5. Department of Gastroenterology and Metabolism; Graduate School of Biomedical Sciences; Hiroshima University; Hiroshima Japan
6. Department of Endoscopy; Hiroshima University Hospital; Hiroshima Japan
7. Department of Gastroenterology and Hepatology; National Center for Global Health and Medicine; Kohnodai Hospital; Ichikawa Japan