1. St Richard's Hospital Chichester; Department of General Surgery; Spitalfield Lane Chichester UK PO19 6SE
2. Royal Free Campus, UCL Medical School; Department of Surgery; Royal Free Hospital Rowland Hill Street London UK NW3 2PF
3. Department of Surgery; UCL Division of Surgery and Interventional Science; 9th Floor, Royal Free Hospital Pond Street London UK NW3 2QG
4. Azienda Ospedaliero-Universitaria Careggi; Endoscopia Chirurgica; Largo Brambilla, 3 Firenze Firenze Italy 50121
5. Ravenna Hospital; Department of Surgery; Randi 5 Ravenna Italy 48121