1. Department of General and Visceral Surgery; Ulm University Hospital ; Ulm Germany
2. Department of General, Visceral and Transplant Surgery; University of Heidelberg; Heidelberg Germany
3. Department of General, Visceral, Thoracic and Vascular Surgery ; Lukas Hospital Neuss ; Neuss Germany
4. Department of Surgery ; Cantonal Hospital Thurgau ; Frauenfeld Switzerland
5. Department of General and Visceral Surgery ; Medical Center, University of Freiburg ; Freiburg Germany