1. University Department of Surgery, The General Infirmary, Leeds LS1 3EX
2. Department of Surgery, Leicester General Hospital, Leicester LE5 4PW
3. Nottingham City Hospital, Hucknall Road, Nottingham NG5 1PD
4. Department of Surgery, Somerset Hospital, 8051 Cape, South Africa
5. Department of Community Medicine, and General Practice, University of Oxford, Oxford OX1 3QN
6. University Department of Clinical Surgery, The Royal Infirmary, Edinburgh, EH3 9YW
7. 4 Hall Close, Bramhope, Leeds LS16 9JQ
8. Division of Surgery, The Victoria Infirmary, Glasgow G42 9TY
9. Ashington Hospital, West View, Ashington, Northumberland NE63 0SA
10. Department of Surgery, Clinical Sciences Building, Leicester Royal Infirmary, Leicester LE2 7LX
11. Henson, Wise and Otteman, Surgical Associates PC, 1015 Robertson, Fort Collins, Colorado 80524, USA
12. Departments of Internal Medicine and Surgery, University Hospital St Luc, B 1200 Brussels, Belgium