[Etiological characteristics of influenza A (H1N1) 2009 virus in Beijing].

OBJECTIVE: To analyze the results of detection on influenza A (H1N1) 2009 virus in Beijing from May 2009 to December 2009 and to understand the epidemiologic characteristics during the pandemic period. METHODS: The study was conducted from the May 1 to December 27, 2009. A total of 101 852 throat swab samples were detected with the real-time RT-PCR assay by the Beijing Network Laboratory. Data was statistically analyzed. RESULTS: 9843 samples showed influenza A (H1N1) 2009 positive, with an overall positive rate as 9.66%. In terms of the positive rates, they were 2.85% from May to June, 3.32% from July to August and 8.35% from September to October. The peak month fell in November (29.67%) and December (24.33%). The positive rates among the following subpopulations were: 8.40% among the suspected cases, 4.75% among close contact cases, 11.46% among the influenza-like illness cases and 7.33% among the cluster cases with fever. Positive cases mainly fell in age groups 5 - 14 and 15 - 24. The ratio of male to female was 1.5:1. CONCLUSION: During the pandemic period of influenza A (H1N1) 2009, positive cases gradually increased during May to November but slowly decreasing in December.

[The significance of different sample types in study of pandemic A (H1N1) influenza diagnosis].

OBJECTIVE: To explore the value of different types of samples, including throat swabs, stools, bloods in pandemic A (H1N1) influenza diagnosis and virus shedding patterns. METHODS: From May to June in 2009, 135 samples were collected from 23 confirmed cases of pandemic influenza A (H1N1) infection, including 99 throat swabs, 14 stools, 11 bloods, 1 respiratory tract washing from 13 confirmed cases and 10 blood samples from other confirmed cases. The virus was detected by real-time RT-PCR, the antibody was detected by haemagglutination inhibition assay. RESULTS: For 99 throat swabs of 13 patients, the median time of the first positive real-time RT-PCR was 1 day (ranged from 0 to 7 days) after the onset of the symptoms of illness; the median length of time duration of positive real-time RT-PCR results from throat swabs was 3 days (ranged from 1 to 15 days). Four cases intermittently released virus. One respiratory tract washing sample was positive. In 14 stools, 8 stools were real-time RT-PCR positive, the positive rate was 57.14%. The median time of the positive real-time RT-PCR was 3 days (ranged from 1 to 4 days) after the onset of the symptoms of illness. In 21 blood samples collected at 2 to 9 days of onset, 1 blood sample was real-time RT-PCR positive, the positive rate was 4.76%. All these 21 blood samples were antibody negative. CONCLUSION: Throat swabs and stools samples can be used as A (H1N1) influenza early diagnosis. The length of time duration of positive real-time RT-PCR in throat swabs was longer than stool samples and intermittently releasing of virus were found in throat swabs. Influenza A H1N1 cases showed the presence of small amount of viremia and antibody was negative in early blood samples (< 9 days).

[The expression of 5 immune molecules on rat peripheral leucocytes after heart transplantation].

AIM: To observe 5 kinds of immune molecule expressions on rat peripheral leucocytes at varying time points after ectopic heart transplantation and explore the mechanism of acute rejection reaction. METHODS: Donor's heart derived from SD rat was transplanted into the abdomen cavity of Wistar rat by anastomosis of donor's aorta and pulmonary artery to recipient's abdominal aorta and inferior-venacava for establishing coronary perfusion. Before and after transplantation, peripheral leucocytes were isolated from venous blood and labelled with the monoclonal antibodies(mAbs) against CD4, CD8, IL-2R, ICAM-I and MHC-II molecules, respectively. The these molecule levels were assessed by flowcytometry. Simultaneity, graft's pathological changes and their survival rate were observed. RESULTS: At 24 hours after transplantation, MHC-II molecule expression was increased, while expressions of CD4, IL-2R and ICAM-I were significantly decreased, but CD8 expression had no change. At 72 hours after operation, the expressions of CD4, CD8 and IL-2R increased and expressions of CD8 and IL-2R reached to peak. At 7-10 days after operation, except that CD4 expression increased continuously, the expressions of 4 other molecules decreased gradually. The survival rate of graft at varying times after operation were 100%( 24 h), 85.7%(3 days), 16.7%(7 days) and, 0 (10 and 12 days), respectively. Pathological examination showed that there was no notable pathological change in cardiac muscle tissue. At the third day after operation, 4 out of 7 transplanted hearts had only grade I A pathological change. Grade II and above grade II pathological changes were observed in all 6 grafts at the 7th day after operation. CONCLUSION: These data indicate that graft rejection reaction begin to appear in first 72 hours, and effector phase of the reaction appear mainly within 3-7 days after heart transplantation.