1 Department of Pediatrics, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan.
2 Department of Pediatrics, Iwaki Kyoritsu General Hospital, 16 Kuzehara, Mimayamachi, Uchigo, Iwaki, Fukushima 973-8555, Japan.
3 Department of Pediatrics, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan. Electronic address: akikuchi-thk@umin.ac.jp.