1. Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan
2. Department of Dental Anesthesiology, Tokyo Dental College, Chiyoda-ku, Tokyo 101-0061, Japan
3. Department of Neuropsychopharmacology, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo 187-8551, Japan
4. Division of Internal Medicine, Department of Medicine, Higashi-Sapporo Hospital, Sapporo 003-8585, Japan
5. Division of Anesthesiology, Koujinkai Daiichi Hospital, Tokyo 125-0041, Japan
6. Department of Anesthesiology, Cancer Institute Hospital, Tokyo 135-8550, Japan
7. Department of Anesthesiology, East Hokkaido Hospital, Kushiro 085-0036, Japan