1. Department of Propaedeutics of Internal Medicine, Gastroenterology and Dietetics Named after S.M. Ryss «Mechnikov North-Western State Medical University» of the Ministry of Health of Russia, 191015 St. Petersburg, Russia
2. Department of Propaedeutics of Internal Diseases, Federal State Budgetary Educational Institution of Higher Education «National Research Mordovian State University Named after. N.P. Ogarev», 430005 Saransk, Russia
3. Clinical and Educational Center, Gastroenterology and Hepatology, St. Petersburg State University, 199034 St. Petersburg, Russia