1. Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources of Western China, College of Life Science, Ningxia University, Yinchuan, China
2. Department of Anatomy and Cell Biology, The University of Iowa, Iowa City, Iowa, USA
3. Key Laboratory of Environmental Factors and Chronic Disease Control, School of Public Health, Ningxia Medical University, Yinchuan, China
4. Department of Pathology, General Hospital of Ningxia Medical University, Yinchuan, China
5. Department of Occupational Disease, The Fifth People's Hospital of Ningxia, Shizuishan, China
6. Department of Pulmonary and Critical Care Medicine, General Hospital of Ningxia Medical University, Yinchuan, China
7. Center of Medical Laboratory, General Hospital of Ningxia Medical University, Yinchuan, China.