1 Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
2 Japan Society for the Promotion of Science, Tokyo, Japan.
3 Department of Internal Medicine, Asahi General Hospital, Chiba, Japan.
4 Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan. ishii@z6.keio.jp.