1. National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan; Daiichi Pure Chemicals Company, Ltd., 3-13-5 Nihombashi, Chuo-ku, Tokyo 103-0027, Japan; eGene, Inc., 17841 Fitch, Irvine, California 92614; and National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan