1. Social Insurance Inatsuki Hospital, Fukuoka 820-02, Japan
2. Department of Gastroenterology, National Kyushu Cancer Center, Fukuoka 815, Japan
3. Department of Clinical Physiology, Tokyo Metropolitan Institute of Gerontology, Tokyo 173, Japan
4. Laboratory of Cellular Metabolism, Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki 444, Japan