1. Department of Gastroenterology, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, U.K.
2. Department of Gastroenterology, Leicester General Hospital, Gwendolen Road, Leicester LE5 4PW, U.K.
3. SHS International Ltd., 100 Wavertree Boulevard, Liverpool L7 9PT, U.K.