1. Center for Medical Education and Career Development; Fukushima Medical University; Fukushima Japan
2. Department of Cardiology; Fukushima Medical University Hospital; Fukushima Japan
3. Department of Gastrointestinal Medicine; Minamisoma Municipal General Hospital; Minamisoma Japan
4. Department of Geriatric Medicine; Kanazawa Medical University; Kahoku-gun Japan
5. Laboratory of Infectious Diseases; Graduate School of Infection Control Sciences; Kitasato University; Minato-ku Japan