1. Department of Nutrition, Faculty of Health Science, Aomori University of Health and Welfare, Mase 58-1, Hamadate, Aomori 030-8505, Japan
2. Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
3. Division of Environmental Technology, Aomori Industrial Research Center, Nogi-yamaguchi 221-10, Aomori 030-0142, Japan