1. From the Autonomic Medicine Section (formerly Clinical Neurocardiology Section), Clinical Neurosciences Program, Division of Intramural Research, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD (R.I., P.S., A.C., C.H., D.S.G.)
2. Department of Pathology, Johns Hopkins School of Medicine, Baltimore, MD (A.Z.R.)
3. Department of Internal Medicine, Chaim Sheba Medical Center, Tel Aviv University Sackler Faculty of Medicine, Israel (Y.S.).