1. Department of Anorectal Physiology, St George Hospital, Sydney, Australia
2. St George Clinical School, University of New South Wales, Sydney, Australia
3. Department of Medicine, University of New South Wales, Sydney, Australia
4. CSIRO Materials Science and Engineering, Lindfield, New South Wales, Australia
5. Department of Colorectal Surgery, St George Hospital, Sydney, Australia
6. Department of Gastroenterology and Surgery, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia