1. University of Cambridge Department of Medicine, Box 157,Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, U.K.
2. SKBPharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, U.K.
3. Clinical Biochemistry, StBartholomew's Hospital, Turner Street, London E1 2AD, U.K.