1. Center for Interdisciplinary Visceral Medicine, Department of Gastroenterology, Gastrointestinal Oncology, Gastrointestinal Infections and Nutritional Medicine, Cologne-Holweide and Merheim Medical Centers, 51109 Cologne, Germany
2. Center for Interdisciplinary Visceral Medicine, Department of Abdominal, Tumor, Transplant and Vascular Surgery, Cologne-Merheim Medical Center, Witten/Herdecke University, 51109 Cologne, Germany