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1.
Chinese Journal of Disease Control & Prevention ; (12): 607-612, 2019.
Article in Chinese | WPRIM | ID: wpr-778719

ABSTRACT

Objective To evaluate the antibody persistence following rabies postexposure prophylaxis (PEP) with 2-1-1 regimen and antibody response to two booster doses. Methods A total of 314 healthy volunteers at year 1, year 2, year 3 who had received a complete rabies PEP using 2-1-1 regimen were recruited. Two booster doses of rabies vaccine were inoculated, and blood samples were obtained before and 14 days after two booster doses. Human rabies virus IgG antibody was evaluated by ELISA, and the antibody levels and antibody positive rates were analyzed. Results The antibody GMC of 303 people at year 1, year 2, year 3 after a complete immunization was 1.33 IU/mL, 1.04 IU/mL and 0.72 IU/mL, with an antibody positive rate of 77.78%, 66.67% and 55.56%, respectively. Among 282 people who received 2 doses for booster immunization, the antibody GMC at day 14 of 1 year, 2 year and 3 year immunization group was 16.83 IU/mL, 19.37 IU/mL and 21.05 IU/mL respectively, which was higher than that before booster immunization (t=16.54, P<0.001; t=13.85, P<0.001; t=16.02, P<0.001). The antibody positive rate was 100.00%, 99.00% and 100.00%, respectively. Conclusions The immune persistence of rabies antibody after PEP with antirabies vaccine using the 2-1-1 regimen is good so as to the immune response after 2 doses of booster immunization in 3 years is effective.

2.
Chinese Journal of Comparative Medicine ; (6): 60-63, 2017.
Article in Chinese | WPRIM | ID: wpr-668619

ABSTRACT

Objective To investigate the treatment and disposal of laboratory animal waste in Beijing area in 2016. Methods Questionnaire, telephone survey, on-the-spot investigation and WeChat were used to survey the basic situation and laboratory animal waste management, including bedding material, excreta, carcasses and experimental consumables,etc. in 164 laboratory animal facilities in Beijing area in 2016. Results The data we have collected were relatively comprehensive and universal, reflecting the currently existing problems. Conclusions This investigation provides a reference for the compilation of the management rules of laboratory animal waste in Beijing.

3.
Chinese Journal of Comparative Medicine ; (6): 16-20, 2017.
Article in Chinese | WPRIM | ID: wpr-663803

ABSTRACT

Objective To observe the effect of different storage time on 14 blood biochemical indexes in rats. Methods Randomly selected 40 adult SD rats were included in this study. Fasting venous blood samples were collected, serum was separated, sealed, and stored in the refrigerator (4℃ and -20℃). The serum parameters were detected at 0 h,4 h,24 h,96 h and 7 d, respectively, using an automatic biochemical analyzer. A total of 14 blood biochemical indexes were detected, including alanine aminotransferase ( ALT ) , aspartate aminotransferase ( AST ) , alkaline phosphatase (ALP), total protein (TP), albumin (ALB), creatinine (CREA-J), uric acid (UA), urea nitrogen (UREA), blood glucose ( GLU) , total cholesterol ( TC) , triglyceride ( TG) , low density lipoprotein cholesterol ( LDL-C) , creatine kinase ( CK) and lactate dehydrogenase ( LDH) . The effects of serum storage time on blood biochemical results were compared. Results The trends of blood biochemical data in male and female rats were consistent. C ompared with the indexes of serum preserved at 4℃ for 0 h, the ALP was significantly reduced after storage for 4 h, 24 h, 96 h, and 7 d (P< 0. 05), ALB were significantly increased after 96 h and 7 d (P< 0. 01), CREA-J was significantly increased after 96 h, 7 d (P<0. 05), UA was significantly increased after 24 h, 9 h, and 7 d (P < 0. 01), and no significant changes in other indicators ( P> 0. 05 ) . Compared with the values of 0 h serum, the serum preserved at -20℃ showed that ALT was significantly increased after 7 d (P < 0. 01), AST significantly increased after 96 h and 7 d (P< 0. 05), TP significantly decreased after 4 h and 24 h ( P< 0. 05 ) , ALB significantly increased after 4 h, 24 h, 96 h, and 7 d ( P< 0. 01 ) , CREA-J significantly increased after 24 h, 96 h, and 7 d (P< 0. 01), UA significantly increased after 4 h, 24 h, 96 h, and 7 d (P< 0. 01), TC significantly increased after 4 h, 24 h, 96 h, and 7 d (P< 0. 01), TG significantly increased after 96 h and 7 d (P< 0. 05), CK significantly increased after 96 h and 7 d (P< 0. 05), LDH significantly increased after 96 h and 7 d ( P < 0. 05 ) , and no significant changes in other indicators ( P > 0. 05 ) . Conclusions The biochemical tests of rat serum should be immediately performed as they were collected, especially for ALP test. For the sera stored at 4℃, the test should be finished in different times:UA test in 4 hours, ALB and CREA-J test in 24 hours, and ALT, AST, TP, UREA, GLU, TC, TG, LDL-C, CK, and LDH test in 7 days.

4.
Acta Physiologica Sinica ; (6): 285-292, 2016.
Article in Chinese | WPRIM | ID: wpr-331655

ABSTRACT

The study was aimed to investigate the effects of total saponins of Panax notoginseng (tPNS) on cobalt chloride (CoCl2)-induced apoptosis of rat bone marrow mesenchymal stem cells (rBMSCs) and the underlying mechanism. rBMSCs were isolated by density gradient centrifugation from Sprague Dawley (SD) rats. After being incubated with different concentrations of tPNS (1, 10, 100 μg/mL) for 48 h, the rBMSCs were stained with EdU and PI for proliferation and cell cycle assay, respectively. CoCl2 group was treated with 300 μmol CoCl2 for 24 h, and different concentrations tPNS groups were treated with 300 μmol CoCl2 plus 1, 10 or 100 μg/mL tPNS. After Annexin V-FITC/PI staining, flow cytometry was applied to measure the cell apoptosis. For mitochondrial membrane potential assay, rhodamine123 and Hoechst33342 staining were used. qRT-PCR was applied to analyze gene expression of Bcl-2 family. The results showed that the proliferation rates of the three concentrations tPNS groups were all higher than that of the control group (all P < 0.05). Compared with control group, only 100 μg/mL tPNS group exhibited increased cell percentage of S and G2 phase. Compared with that in control group (without CoCl2), the apoptotic rate was increased by 14.2% in CoCl2 group. And the apoptotic rates were reduced by 14.4%, 12.8% and 13.9% in three concentrations tPNS groups, compared with that in CoCl2 group (all P < 0.01). CoCl2 could decrease the mitochondrial membrane potential, while different concentrations of tPNS reversed the inhibitory effect of CoCl2. Bcl-2 and Bcl-xl mRNA expressions in all tPNS groups were higher than those in CoCl2 group (all P < 0.05). Moreover, 10 and 100 μg/mL tPNS groups showed lower ratios of Bax/Bcl-2, compared with CoCl2 group. The results suggest that tPNS protects the rBMSCs against CoCl2-induced apoptosis through improving the cell mitochondrial membrane potential, up-regulating the expressions of anti-apoptosis genes Bcl-2 and Bcl-xl, and reducing the Bax/Bcl-2 gene expression ratio.


Subject(s)
Animals , Rats , Apoptosis , Bone Marrow Cells , Membrane Potential, Mitochondrial , Mesenchymal Stem Cells , Mitochondria , Panax notoginseng , Rats, Sprague-Dawley , Saponins
5.
Acta Physiologica Sinica ; (6): 359-366, 2011.
Article in Chinese | WPRIM | ID: wpr-335978

ABSTRACT

The aim of this study was to investigate the influence of endothelial like cells differentiated from rat bone marrow mesenchymal stem cells (rBMSC-ECs) on angiogenesis and the effect of Rho kinase (ROCK) inhibitor using an in vitro model of cells co-cultured with rat aorta ring. Cell proliferation capability was detected by MTT method. The rBMSC-ECs were co-cultured with rat aorta ring in rat tail collagen and endothelial medium. A ROCK specific inhibitor, HA-1077 at different concentrations (0, 10, 30 and 60 mmol/L, respectively) was added into the medium of ring-cell co-culture. The protein expression of ROCK I and ROCK II were detected by Western blot. On the third day of cultivation, the branch number of neogenetic microvessels increased by 34.5% in ring-cell co-culture group compared with that in simple aorta ring group (P < 0.01). Compared with that in ring-cell co-culture group, it was significantly decreased by 57.70%, 64.13% and 48.23% respectively in three concentrations of HA-1077 groups (all P < 0.01). However, on the sixth day, rBMSC-ECs proliferated and migrated to the nearby aorta ring, and the growth of microvessels became slow. On the ninth day, some of neogenetic microvessels were retracted, some became thicken, coarsen and lengthen, and some of rBMSC-ECs were sprouting and forming capillary like picture. The protein expression of ROCK I/II was slightly higher in ring-cell co-culture group than that in simple aorta ring group. But, in three concentrations of HA-1077 groups, it was slightly lower than that in ring-cell co-culture group. By using rhodamine-phalloidin staining and laser scanning confocal fluorescence microscope, it showed that there were a lot of the F-actin cytoskeletons in neogenesis microvessels of aorta ring, and there were a lot of thick and long stress fibers in the cells. F-actin-rich surface protrusions at the leading edge of the cell were also shown. Another ROCK inhibitor, Y-27632 (10 μmol/L) induced the actin cytoskeleton reorganization: F-actins appeared to be peripheral fibers at outer area of cell; stress fiber and filopodia disappeared. These results suggest that rBMSC-ECs themselves can be differentiated into new microvessels and facilitate angiogenesis when they are co-cultured with rat aorta ring. The mechanisms involve ROCK activation and F-actin cytoskeleton recombination.


Subject(s)
Animals , Male , Rats , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine , Pharmacology , Aorta, Thoracic , Cell Biology , Bone Marrow Cells , Cell Biology , Cell Differentiation , Physiology , Cells, Cultured , Coculture Techniques , Endothelial Cells , Cell Biology , Mesenchymal Stem Cells , Cell Biology , Neovascularization, Physiologic , Physiology , Rats, Sprague-Dawley , rho-Associated Kinases , Metabolism
6.
Chinese Journal of Virology ; (6): 202-207, 2010.
Article in Chinese | WPRIM | ID: wpr-297883

ABSTRACT

To study the molecular epidemiological characteristics of norovirus gastroenteritis outbreaks in Guangdong, we collected fecal and anal swabs specimens from 24 outbreaks of acute gastroenteritis from 2005 to 2008 to detect norovirus. Specimens were detected by RT-PCR and then sequenced. The descriptive data were also collected. According to our research, 19 of 24 outbreaks of gastroenteritis were positive for norovirus. The occurrence time was from October to next February mainly. The strains in 2005 belonged to G II-3 genotype and all outbreaks occurred in kindergarten and school. But from autumn of 2006, the outbreaks were all caused by G II-4/2006b variant and occurred in universities and community. The number of outbreaks in 2007 increased greatly and covered all over province. The nucleotide sequences of Guangdong strains in some sites showed high regional identity. Our results showed that with the shift of genotype from G II-3 to G II-4, occurrence of norovirus outbreaks increased greatly. The outbreaks of norovirus caused by G II-4/2006b variant spreaded widely and the involved population covered children and adult, indicating the strong invasiveness of this variant.


Subject(s)
Adolescent , Adult , Child , Humans , Young Adult , Base Sequence , China , Epidemiology , DNA-Directed RNA Polymerases , Genetics , Disease Outbreaks , Gastroenteritis , Epidemiology , Molecular Sequence Data , Norovirus , Classification , Genetics , Phylogeny , Reverse Transcriptase Polymerase Chain Reaction
7.
Chinese Journal of Preventive Medicine ; (12): 628-631, 2009.
Article in Chinese | WPRIM | ID: wpr-316122

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the etiology and source of an infectious diarrhea outbreak and control the epidemic.</p><p><b>METHODS</b>Through the retrospective cohort study, we had surveyed all the residents who complained symptoms of diarrhea or vomiting since Nov. 20th,2007 from the five villages in the north of town Y, and collected hygiene information on the water supply system of the five villages, the environment information of three villages and hygiene information of some case-indexed families, and tested the etiological biomarker, including nucleoside acid of norovirus through Real-time PCR and nested PCR technologies.</p><p><b>RESULTS</b>From Nov. 24th to Dec. 3th in 2007, 435 diarrhea or vomiting cases were found in the north of Y town, where tap water A was supplied for daily use. The attack rate was 12.93%. The diarrhea cases were distributed among all country groups who has used tap water A and the attack rate was ranged from 5.21% (20/384) to 21.23% (100/471). Drinking the tap water A was significantly associated with an increased risk of infection (RR = 9.246, 95% CI: 6.25 -13.68). About 85.9% (262/ 305) of the cases were from Nov. 25th to 27th. An investigation of a country of S2 group showed that the incidence of different age groups was distributed as the following: 0 - year-old 20.0% (3/15); 10 - year-old 17.3% (9/52); 20 - year-old 15.2% (16/105); older than 60 year-old 23.3% (7/30). No statistical significance was identified between age and infection(chi2 = 1.15, P >0.05). Most of the patients were not serious and well prognostic, and no hospitalized or dead cases were reported. On site investigation and daily water quality monitoring showed that disinfection procedures were not strictly followed. The monitoring data also indicated the bacteriology index of tap water A was disqualified. The test of Salmonella, Shigella and Staphylococcus aureus were negative in two vomit and one stool samples from patients. Three specimens by Real-time PCR, and six by nested PCR were positive for norovirus among the three feces and three anal swabs samples. With the drinking water sterilization and health education, the epidemic had been controlled rapidly and effectively.</p><p><b>CONCLUSION</b>The epidemic was a diarrhea outbreak that might be caused by norovirus through drinking the contaminated tap water A.</p>


Subject(s)
Adolescent , Adult , Child , Child, Preschool , Humans , Infant , Infant, Newborn , Middle Aged , Young Adult , Caliciviridae Infections , Epidemiology , Cohort Studies , Diarrhea , Epidemiology , Virology , Disease Outbreaks , Incidence , Retrospective Studies , Water Pollution , Water Supply
8.
Acta Physiologica Sinica ; (6): 339-346, 2009.
Article in Chinese | WPRIM | ID: wpr-302443

ABSTRACT

The present study was designed to test whether Rho-kinase (ROCK) specific inhibitor fasudil (HA-1077) could contribute to migration and vasculogenesis of endothelial cells differentiated from rat bone marrow mesenchymal stem cells (rBMSCs) in vitro. rBMSCs were separated by gradient centrifugation on lymphocytes separation medium from bone marrow of Sprague-Dawley rats, and were cultured, purified and expanded in vitro. Cells of passage 2 to 3 were induced to differentiate into endothelial lineage cells by HG-DMEM plus EGM-2. These cells were identified as endothelial cells with positive factor VIII and Ulex europaeus agglutinin-1 expressions and DiI-Ac-LDL uptake. HA-1077 and VEGF synergistically promoted cell migration, especially in response to transwell chamber assay. When the cells were cultured on ECMatrix™, they showed cellular protrusions and/or cords of aligned cells resembling primitive capillary-like structures at 8 to 12 h of incubation. HA-1077 promoted cell migration and formation of capillary-like tubes. The length of the total capillary tubes was longer than that in the control group (P<0.05). When the cells were exposed to a combination of VEGF and HA-1077, the number of the capillary-like networks and the stability of tube increased. The results obtained suggest that HA-1077 can promote migration and vasculogenesis of endothelial cells differentiated from rBMSCs in vitro.


Subject(s)
Animals , Rats , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine , Pharmacology , Bone Marrow Cells , Cell Biology , Cell Differentiation , Cell Movement , Endothelial Cells , Cell Biology , Mesenchymal Stem Cells , Cell Biology , Rats, Sprague-Dawley , rho-Associated Kinases
9.
Chinese Journal of Epidemiology ; (12): 145-150, 2008.
Article in Chinese | WPRIM | ID: wpr-287852

ABSTRACT

<p><b>OBJECTIVE</b>Through systematic monitoring of the number and strain types of O1 and O139 Vibrio cholerae in the Pearl River estuary waters to analyze it's relevance with the temperature of environment, and the relevance between strains in water and isolates during outbreaks and epidemics as well as to estimate the methods used for environmental water detection and the potential role in cholera surveillance program.</p><p><b>METHODS</b>Twenty-four stations along the Pearl River were selected and the water samples were collected monthly from March 2006 to February 2007. V. cholerae O1 and O139 strains were isolated from the samples. Real-time PCR established in our laboratory was used to detect V. cholerae O1 and O139. Air temperature and water temperature were collected during sampling. Pulsed field gel electrophoresis (PFGE) was applied in molecular typing of the isolates.</p><p><b>RESULTS</b>862 water samples were collected during the study period. A total number of 77 O1 and O139 V. cholerae were isolated in 67 water samples and the positive rates were 7.77% for isolation and 26.33% for real-time PCR. Seasonal trend of positive rates by month were approximately coincident with the change of water temperature. The positive rates in the stations in urban area were higher than those in other areas. Toxigenic O139 strains were found in one station located in downstream of a marine market. Most of the O1 and O139 isolates were non-toxigenic. No trend of seasonal variation of the strains was noticed. Within these 75 isolates, 49 PFGE patterns were identified and the patterns differed widely with the similarity of 57.4% - 100%.</p><p><b>CONCLUSION</b>V. cholerae existed as the natural habitat in estuary water of the Pearl River and showed obvious genetic diversity. Data from monitoring waters might show the separation of strains with certain seasonal association. But the crowd did not show the relationship between the infections. Results from water surveillance program might provide indicators on the appearance of cholera pathogen which might be used in assessing the environmental risk of cholera epidemics as well as the alert of cholera.</p>


Subject(s)
Electrophoresis, Gel, Pulsed-Field , Environmental Monitoring , Phylogeny , Polymerase Chain Reaction , Seasons , Temperature , Vibrio cholerae O1 , Classification , Genetics , Vibrio cholerae O139 , Classification , Genetics
10.
Chinese Journal of Burns ; (6): 181-184, 2005.
Article in Chinese | WPRIM | ID: wpr-303669

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the changes in endothelial cytoskeletal reorganization and the role of Rho in the signal transduction pathway.</p><p><b>METHODS</b>ECV304 cells were cultured and randomly divided into following groups: i.e. sham (with normal rat serum treatment), burn (with burn rat serum treatment), Y (with 30 micromol/L Rho kinase inhibitor Y-27632 treatment), burn plus Y (pretreatment of cells with burn serum before treated with 30 micromol/L Y-27632), Y plus burn (pretreatment of cells with Y-27632 for 1 hour before treated with burn serum), LPA (with normal rat serum and 13 micromol/L LPA), and LPA plus Y (pretreatment of cells with LPA before treated with Y-27632) groups. The indices were examined at 6, 7 and 8 posttreatment hours (PTH) in all groups except in Y group. The endothelial morphology was observed with HE staining. Endothelial cytoskeleton was observed by dual-fluorescence labeling of filamenta (F) with Rhodamine-phalloidin and monomer (G) with oregon green labeled DNAase. The actin content in the cells in all groups was measured with flow cytometry.</p><p><b>RESULTS</b>In sham and control group, the cells were in fusiform or polygonal shape, with satisfactory growth; filamentous actin (F-actin) was mainly distributed in the peripheral site of the cytoplasm and formed peripheral filamental band. The cells became confluent to form a single layer with reticular structure. Globular actin (G-actin) was concentrated in the nucleus and per nucleus. In burn group, after 6 hours of burn serum treatment, the ability of cells to adhere to vessel wall was weakened, and a striking reorganization of the actin cytoskeleton and the formation of the stress fibers were found. Furthermore, the fluorescent intensity of the peripheral filament bands was weakened, and dispersed actin monomers were seen in the cytoplasm. This reaction was enhanced along with elapse of stimulation time. In burn plus Y or Y plus burn group, the cells grew and adhered well to the wall of culture vessel. The distribution of the filamentous actin was the same as the sham group, while the stress fiber decreased in amount obviously. The structure of globular actin was condensed with little G-actin in the cytoplasm. The changes in actin cytoskeleton in LPA group was similar to that in burn group. The effects of LPA on actin reorganization could also be reversed by Y-27632. The content of F-actin in burn group at 6 PTH (0.63 +/- 0.07) was lower than that in sham group (0.75 +/- 0.08), while the content of G-actin in burn group (1.28 +/- 0.27) was higher than that in sham group (1.16 +/- 0.16, P > 0.05).</p><p><b>CONCLUSION</b>Burn serum induces vascular endothelial actin cytoskeleton reorganization in endothelial cells via the Rho-dependent signal pathway. Similar to the effect of LPA, this effect could be reversed by Y-27632.</p>


Subject(s)
Animals , Humans , Male , Rats , Actins , Metabolism , Amides , Pharmacology , Burns , Blood , Metabolism , Cells, Cultured , Cytoskeleton , Metabolism , Endothelial Cells , Metabolism , Endothelium, Vascular , Pyridines , Pharmacology , Rats, Sprague-Dawley , Serum , Metabolism , Signal Transduction , rho-Associated Kinases , Metabolism
11.
Chinese Journal of Epidemiology ; (12): 347-349, 2003.
Article in Chinese | WPRIM | ID: wpr-348870

ABSTRACT

<p><b>OBJECTIVE</b>To analyze the epidemiological features of the index cases of severe acute respiratory syndrome (SARS) occurred in different cities in Guangdong province and to trace for the source of infection.</p><p><b>METHODS</b>Standardized individual case inventory was adopted to conduct investigation on index cases and on persons who had close contact with index cases in Guangdong province. Data on the epidemiological characteristics, secondary cases and the links among index cases were analyzed.</p><p><b>RESULTS</b>Between November 16, 2002 and April 16, 2003, there had been 13 index cases of SARS including 3 cadres, 3 farmers, 2 retirees, 2 workers and 1 shop attendant, reported from 13 cities in Guangdong province. Between November 2002 and January 2003, there had been 7 cities reported to have identified index cases of SARS with 6 of them being infected in their own cities and 1 imported from Guangzhou city. All of the cases had no close contacts to similar patients but 6 of them later caused 2nd or even 3rd generation cases of SARS. Most cases hit young people (7/13) with a sex ratio of 1:0.6. The fatality rate of index cases was high (4/13).</p><p><b>CONCLUSION</b>No evidence showed that there was direct transmission among the index cases. Data regarding the geographical origin of those index cases led to the assumption that the infection had started in six cities of Pearl river delta region and the Hong Kong Special Administrative Region.</p>


Subject(s)
Adolescent , Adult , Aged , Female , Humans , Male , Middle Aged , China , Epidemiology , Contact Tracing , Hong Kong , Epidemiology , Prevalence , Severe Acute Respiratory Syndrome , Epidemiology
12.
Chinese Journal of Preventive Medicine ; (12): 227-232, 2003.
Article in Chinese | WPRIM | ID: wpr-291868

ABSTRACT

<p><b>OBJECTIVE</b>To explore epidemiological features and risk factors of severe acute respiratory syndrome (SARS) in Guangdong Province of China, so as to work out effective strategies for its better control.</p><p><b>METHODS</b>A total of 1 511 clinically confirmed SARS cases in Guangdong Province of China from November 16, 2002 to Jun 15, 2003 were retrospectively analyzed.</p><p><b>RESULTS</b>The first SARS case was identified in Foshan municipality on November 16, 2002, followed by 1 511 clinically confirmed cases (including 58 deaths) up to May 15, 2003. Of all cases, health care workers and community family cluster cases accounted for 19.38% and 12.04%. 65.86% SARS patients aged 20 - 49 years, and increased incidence was positively related to their ages. 95.97% cases lived in the following five cities around Pearl Delta Area: Foshan, Guangzhou, Shenzhen, Zhongshan, and Jiangmen. Eleven early reported cases in the communities took animal-related positions. Face-to-face contacts with infected droplets were the main transmission route. An epidemic peak occurred during January 28 to February 26, and those cases accounted for 50.69% of total. Incidence, mortality, and case fatality of SARS were 1.77/100,000, 0.07/100,000, and 3.84% respectively. The mean incubation period was 4.5 days.</p><p><b>CONCLUSION</b>The most effective way to control SARS is to break the chain of transmission from infected to healthy persons-early identification, prompt and effective isolation, and vigorous close contact tracing. Hospital infections among health care workers is critical. Several observations support the hypothesis of an animal origin for the disease.</p>


Subject(s)
Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Humans , Infant , Male , Middle Aged , China , Epidemiology , Disease Outbreaks , Follow-Up Studies , Incidence , Infectious Disease Transmission, Patient-to-Professional , Retrospective Studies , Severe Acute Respiratory Syndrome , Epidemiology
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