1. Department of Gastroenterology, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita 010-8543, Akita, Japan
2. Department of Gastroenterology, Yuri Kumiai General Hospital, 38 Ienoushiro, Kawaguchi, Yurihonjo 015-8511, Akita, Japan
3. Department of Gastroenterology, Yokote Municipal Hospital, 5-31 Negishi, Yokote 013-8602, Akita, Japan
4. Department of Gastroenterology, Hiraka General Hospital, 3-1 Yatsukuchi, Maego, Yokote 013-8610, Akita, Japan
5. Department of Gastroenterology, Omagari Kosei Medical Center, 8-65 Omagaritori, Daisen 014-0027, Akita, Japan
6. Department of Gastroenterology, Akita Kosei Medical Center, 1-1-1 Nishibukuro, Iijima, Akita 011-0948, Akita, Japan
7. Department of Gastroenterology, Akita Red Cross Hospital, 222-1 Nawashirosawa, Kamikitatesaruta, Akita 010-1495, Akita, Japan
8. Department of Gastroenterology, Honjo-Daiichi Hospital, 110 Iwabuchishita, Yurihonjo 015-8567, Akita, Japan
9. Department of Gastroenterology, Shirane Hospital, 5-29 Kyokuhokusakae, Akita 010-0922, Akita, Japan
10. Department of Gastroenterology, Omori Municipal Hospital, 245-205 Sugouta, Omori, Yokote 013-0525, Akita, Japan