1. Department of Medicine (H.J.W., A.L.), University of Birmingham, Birmingham B15 2TT, United Kingdom;
2. Department of Anatomy and Cell Biology (M.B.), UMDS, Guy’s Hospital, London SE1 9RT, United Kingdom;
3. Department of Medicine, Physiology and Paediatrics (D.J.H.), Lawson Research Institute, London, Ontario N6A 4V2, Canada;
4. Department of Surgery (S.C.-H., J.M.P.H.), University of Bristol, Bristol, BS2 8HW, United Kingdom