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Objective@#The serotype screening of Shigella flexneri from 1934 to 1965 preserved by the National Center for Medical Culture Collections was carried out, and the molecular characteristics of the serotype conversion strains were studied.@*Methods@#Serotyping of Shigella flexneri in this study was conducted by slide agglutination and multiplex PCR, respectively. The gtrⅡ gene sequence alignment and pulsed field gel electrophoresis typing were performed on the serotype conversion strains.@*Results@#Among the 255 strains of Shigella flexneri preserved in CMCC (B) from 1934 to 1965, 79 were carrying gtrⅡ gene, of which 19 strains and 1 strain were agglutinated with the Y serotype and X serotype, respectively, and furthermore, the multiplex PCR assays results showed serotypes 2a and 2b, respectively, and the strains were considered to have serotype conversion. The 20 strains carrying the gtrⅡ gene showed multiple nucleotide mutations. Besides 3 strains of 3 amino acid mutations, the amino acid sequences of the other 17 strains showed a stop codon in advance, resulting in functional inactivation of gtrⅡ. PFGE analysis revealed that the similarity between the serotype Y strain carrying the gtrⅡ gene and the serotype 2a strain was 75.8%-100%, and the similarity between the serotype X strain carrying the gtrⅡ gene and the serotype 2b strain was 81.6%-100%.@*Conclusion@#Mutations in the gtrⅡ gene are more complicated in serotype-transforming Shigella flexneri serotype Y or X strains. Molecular typing suggests that the serotype-transforming Shigella flexneri serotype Y or X strains may be derived from the Shigella flexneri serotype 2a or 2b, and advance the serotype conversion to 1949.
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Objective To identify and rename one strain stored in National Center for Medicine Culture Collections ( CMCC) and used for tracheitis vaccine production. Methods The test strain CMCC (B)29108 and the type strain DSM30007T were cultured on NA medium. Characteristics in morphology, physiology, biochemistry and fatty acid profile were compared between the two strains. Phylogenetic analysis was based on 16S rRNA and rpoB gene sequences, together with the DNA-DNA hybridization assay. Results A Comparative analysis of a partial sequence of the 16S rRNA gene sequence revealed that the CMCC( B) 29108 strain was closed to the Acinetobacter species and showed the highest similarity with the type strain Acinetobacter baumannii DSM30007T. Moreover, the CMCC(B)29108 strain was highly similar to type strain DSM30007T in morphology, physiology, biochemistry and fatty acid profile. On the phylogenetic tree based on 16S rRNA and rpoB gene of all Acinetobacter members, the CMCC(B)29108 strain steadily clustered into one independent branch only with the DSM30007 T strain with a DNA-DNA hybridization value of 100%. Conclusion The CMCC(B)29108 strain that is one of the strains used for the production of tracheitis vac-cine should be assigned to the species of Acinetobacter baumannii based on its phenotypic, phylogenetic and chemotaxonomic characteristics.
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Objective To investigate the employment status of higher vocational medical col-lege graduates in Hainan province, analyze the existing employment problems, and put forward some effective suggestions. Methods A questionnaire was applied to survey the employment problems of 1 048 medical graduate in 11 medical related field of Grade 2012. A total of 989 valid questionnaires were collected. The questionnaires covered six aspects including graduates' basic information, their employment intention, access to employment information channel, service and satisfaction about school employment agencies, and employment psychology etc. SPSS 13.0 was used to analyze the statistical numbers in each option and the percentage was calculated. Results Only 22.9%(227/989) of the graduates were willing to accept the provincial employment, 49.1%(486/989) of the graduates obtained employment information channels through the school employment sector; 10.6%(105/989) of gradu-ates expressed dissatisfaction with employment services; graduates' entrepreneurial intention reached 26.9%(267/989); only 19.8% of graduates signed employment agreement, and 25.1%(248/989) of gradu-ates face the employment with anxiety and confusion. Conclusion The higher vocational medi-cal graduates in Hainan provinces need to change their employment concept and school employment guidance needs strengthening to link up the employer position requirements and expectations of grad-uates employment. Besides, the school enrollment professional settings and employment market demand also need to be linked up, to guarantee the system interface between career guidance, internship and training base.
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Objective To comparatively analyze the advantages and disadvantages between a double immune-diffusion assay and a rate nephelometer analysis for the detection of antigen activity of pneu -mococcal capsular polysaccharides .Methods The antigen activity of pneumococcal capsular polysaccharides of serotypes 1,6B,9V,10A,14 and 19A from four manufacturers and ATCC were analyzed by a double im-mune-diffusion assay and a rate nephelometer analysis , respectively .The effects of antiserum samples and gain values on the rate response value were evaluated .Results The sample 4 of type 9V showed no antigeni-city with a rate response value similar to that of negative control as indicated by both tests .However ,the pre-cipitation lines and the rate response values presented by other polysaccharide samples differed in a wide range.Results of the rate nephelometer analysis were not affected by the anti -serum samples from different sources and the gain values .Conclusion The rate nephelometer analysis could quantitatively analyze the antigen activity of pneumococcal capsular polysaccharides .
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Objective To establish a standardized quantitative enzyme-linked immunosorbent as-say ( ELISA) recommended by WHO for the detection of human IgG antibodies specific for Streptococcus pneumoniae capsular polysaccharides ( Pn PS ELISA ) .Methods According to the WHO recommended standard Pn PS ELISA protocol , capsular polysaccharide concentrations of 13 serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 23F) of Streptococcus pneumonia for coating were optimized;the ELISA plates and AP conjugated goat anti-human IgG antibody for the detection were experimentally selected .Using the established assay parameters assured by testing quality control standards ( QCs) provided by WHO refer-ence laboratory , a panel of 16 LIBP ( Lanzhou Institute of Biological Products Co .Ltd.) QCs were measured for comparison analysis between WHO reference laboratory and LIBP laboratory .In the meantime , the range of IgG concentrations of an internal QC panel 907 for 13 serotypes of pneumococcal capsular polysaccharide were established for routine QC work in LIBP laboratory , and inter-assay precision within LIBP laboratory was assessed as well .Results The standardized Pn PS ELISA assay established in LIBP laboratory met the criteria required by WHO .There was a high correlation between the data collected by WHO reference labora -tory and LIBP laboratory (slope=0.94, coefficient of correlation r=0.97, P<0.05).Eighty one percent of IgG concentrations measured by LIBP laboratory were within the range of ±40%of those measured by WHO reference laboratory , which met the criteria of 75%data falling within the ambit of ±40%of assigned values commonly used for comparison .The ranges of IgG concentration in LIBP QC 907 for 13 serotypes had been established.The inter-assay precision in LIBP laboratory was high with coefficiency of variation ( CV) less than 30%.Conclusion LIBP laboratory has successfully established the standardized ELISA recommended by WHO for quantitative detection of human IgG antibodies against pneumococcal capsular polysaccharides (Pn PS ELISA).The range of IgG concentrations in LIBP QC 907 for 13 serotypes of pneumococcal capsular polysaccharide are also established for routine quality-control practice .
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Objective To analyze the structures and molecular weight distributions of the capsular polysaccharides from 6 serotypes of pneumococcus .Methods The structures of pneumococcal capsular pol-ysaccharides of 6 serotypes were analyzed by 1 H nuclear magnetic resonance ( NMR) .Chemical shifts of all characteristic protons were investigated to analyze polysaccharide integrity and inter -assay consistency .High performance size exclusion chromatography-multi angle laser light scattering ( HPSEC-MALLS) was used to measure the molecular weights .Results The chemical shifts of all characteristic protons of the pneumococ-cal capsular polysaccharides of 6 serotypes were consistent with the standard chemical shift .The weight-aver-age molecular mass of the pneumococcal capsular polysaccharides ranged from 7.182×104 g/mol(for serotype 19A) to 1.273×106 g/mol(for serotype 9V)examined by HPSEC-MALLS.Conclusion The structures and molecular weight distributions of pneumococcal capsular polysaccharides could be rapidly and effectively ana -lyzed by 1 H NMR and HPSEC-MALLS.Moreover, C-PS and acetate contained in capsular polysaccharides could also be detected .HPSEC-MALLS is an applicable method for the quantitative analysis of molar mass distributions in different serotypes of pneumococcal capsular polysaccharides . Although 1 H NMR and HPSEC-MALLS have been accepted as the quality control measurements by WHO , to use them as the re-placements of the traditional QC method still needs further investigation .