E.I. Krestova - Junior Research Scientist, Federal State Budgetary Institution «Privolzhsky Federal Re-search Medical Centre» of the Ministry of Health of the Russian Federation. E-mail: ka-tya_rudneva@mail.ru M.Y. Lebedev - Ph.D. (Med), Senior Research Scientist, Federal State Budgetary Institution «Privolzhsky Federal Research Medical Centre» of the Ministry of Health of the Russian Federation. E-mail: miklgito@mail.ru V.I. Ashkinazi - Ph.D. (Med), Senior Research Scientist, Federal State Budgetary Institution «Privolzhsky Federal Research Medical Centre» of the Ministry of Health of the Russian Federation. E-mail: vla-dash@yandex.ru