1. Department of Internal Medicine, Seoul National University College of Medicine and Clinical Research Institute, Seoul National University Hospital (T.Y.K., Y.J.P., D.J.P., B.Y.C.), Seoul 110-744, Korea
2. Department of Internal Medicine, Dankook University College of Medicine (H.C.), Cheonan 330-715, Korea
3. Department of Internal Medicine, Asan Medical Center, University of Ulsan, College of Medicine (W.B.K.), Seoul 110-744, Korea
4. Edison Biotechnology Institute and Ohio University College of Osteopathic Medicine (L.D.K.), Athens, Ohio 45701