1. Department of Gastroenterology; Mongolian National University of Medical Sciences; Ulaanbaatar Mongolia
2. Endoscopy Unit; Mongolia-Japan Teaching Hospital; Mongolian National University of Medical Sciences; Ulaanbaatar Mongolia
3. Department of Medicine, Gastroenterology and Hepatology Section; Baylor College of Medicine; Houston TX USA
4. Department of Environmental and Preventive Medicine; Oita University of Medicine; Yufu Japan
5. Department of Molecular Virology and Microbiology; Baylor College of Medicine; Houston TX USA
6. Department of Molecular Pathology; Oita University of Medicine; Yufu Japan
7. Department of Endoscopy; Mongolian National Cancer Center Hospital; Ulaanbaatar Mongolia