1. Laboratory of Biochemistry, School of Veterinary Medicine, Azabu University, Sagamihara, Kanagawa 252-5201, Japan
2. Laboratory of Radiation Biology, Department of Applied Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
3. Department of Radiology, The Geisel School of Medicine, Dartmouth College, Lebanon, New Hampshire 03756, US