1. Department of General and Visceral Surgery, Albert-Ludwigs-University, Hugstetter Straße 55, 79106 Freiburg, Germany
2. Department of Surgery, Champain de Chalons, 2 Rue Charles Simon, 51308 Vitry-le-France, Frankreich, France
3. Department of Physiology, Silesian Medical University, Jordana 19, 41-800 Zabrze, Poland
4. Department of Laparoscopic Surgery, International Medical Center, P.O. Box 2173, Jeddah 21451, Saudi Arabia