1. Department of Respirology, Graduate School of Medicine, Chiba University, Chiba, Japan
2. School of Medicine, Chiba University, Chiba, Japan
3. Department of Respiratory Medicine, Kawasaki Municipal Hospital, Kawasaki City, Japan
4. Department of Pediatrics, Yamagata University School of Medicine, Yamagata City, Japan
5. Department of Pediatrics, Miyukikai Hospital, Kaminoyama, Japan