1 Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1, Seiryomachi, Aobaku, Sendai, Miyagi, 980-8574, Japan.
2 Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1, Seiryomachi, Aobaku, Sendai, Miyagi, 980-8574, Japan. Electronic address: r.shibuya@rm.med.tohoku.ac.jp.