1. Department of Respiratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
2. Department of Respiratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
3. Department of Respiratory Medicine, The First Affiliated Hospital of Hainan Medical University, Haikou, Hainan 570102, P.R. China
4. Far Eastern Scientific Center of Physiology and Pathology of Respiration, Russian Academy of Medical Sciences, Blagoveshchensk 675000, Russia