1. Development Chemistry Department, GlaxoWellcome Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, U.K., Physical Sciences Department, GlaxoWellcome Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, U.K., International Development Biomet, GlaxoWellcome, Park Road, Ware, Hertfordshire, SG12 ODP, U.K., Biological Chemistry, Division of Biomedical Sciences, Imperial College of Science, Technology and Medicine, Sir Alexander Fleming Building, South Kensington SW7 2AZ U.K.