1. Prince Henry's Institute of Medical Research (J.Z.S., M.J.Y.), Monash University, Clayton 3168, Victoria, Australia
2. Monash Medical Centre (J.Z.S.), Monash University, Clayton 3168, Victoria, Australia
3. Medicine (J.Z.S., M.J.Y.) Monash University, Clayton 3168, Victoria, Australia
4. Departments of Physiology (M.J.Y.), Monash University, Clayton 3168, Victoria, Australia