1. Chiba University Graduate School of Medicine Department of General Medical Science, , Chiba, Japan
2. Eastern Chiba Medical Center Department of Metabolism and Endocrinology, , Chiba, Japan
3. Eastern Chiba Medical Center Department of General Internal Medicine, , Chiba, Japan
4. International University of Health and Welfare Narita Hospital Department of General Internal Medicine, , Chiba, Japan
5. Eastern Chiba Medical Center Department of Neurosurgery, , Chiba, Japan