1. Departments of Medicine and Surgery, St. Thomas Hospital (J.G., S.L., K.B., F.S., P.S., D.R.-J.), London SE1 7EH, United Kingdom
2. Department of Medicine, Princess Alexandria Hospital (J.W., R.C.), Brisbane, Queensland 4102, Australia
3. the Cyclotron Unit, Hammersmith Hospital (T.S., L.S., A.R.), London W12 OHS, United Kingdom