1. Clinical Research Center; Guangdong Medical College; Zhanjiang Guangdong 524001 China
2. Department of Hematology; the First Affiliated Hospital, Medical School of Xi'an Jiaotong University; Xi'an 710061 Shanxi China
3. Department of Medicine; Northwestern University Feinberg School of Medicine and Jesse Brown VA Medical Center; 240 E. Huron, McGaw M-330 Chicago Illinois 60611