1. The University of Texas Health Science Center at Tyler , Tyler, TX, USA
2. University of Tsukuba Hospital , Tsukuba, Ibaraki, Japan
3. Chiba University Hospital , Chiba, Chiba, Japan
4. College of Medicine, School of Medicine and Health Sciences, University of Tsukuba , Tsukuba, Ibaraki, Japan
5. Division of General Internal Medicine, Department of Internal Medicine, Tokyo Medical University Ibaraki Medical Center , Ibaraki, Japan