1. Department of Gastroenterology, Hepatology and Transplantational Medicine, University Hospital Essen, and Faculty of Medicine, University of Duisburg-Essen, Essen, Germany, Essen, Germany
2. Department of General, Visceral and Transplant Surgery, University Hospital Essen, and Faculty of Medicine, University of Duisburg-Essen, Essen, Germany, Essen, Germany