1. Department of Hygiene and Public Health, School of Medicine, Iwate Medical University, 19-1 Uchimaru, Morioka, Iwate 020-8505, Japan
2. Department of Chemistry, Liberal Arts and Sciences, Iwate Medical University, 3-16-1 Honcho-dori, Morioku, Iwate 020-0015, Japan
3. Cyclotron Research Center, Iwate Medical University, 348-58 Tomegamori, Takizawa, Iwate 020-0173, Japan