Department of Gastroenterology, Health Promotion Center, Yonsei University Gangnam Severance Hospital, Seoul 158-050, South Korea
Department of Internal Medicine, Ewha Medical Research Institute, Ewha University Mokdong Hospital, Ewha Womans University School of Medicine, Seoul 158-710, South Korea
Department of Pathology, Ewha University Mokdong Hospital, Ewha Womans University School of Medicine, Seoul 158-710, South Korea