Analysis of oprD gene in imipenem-intermediate clinical isolates of Pseudomonas aeruginosa / 中国感染与化疗杂志

Objective To analyze the mechanism of imipenem resistance in Pseudomonas aeruginosa clinical isolates. Methods? Antibiotic?resistance?was?analyzed?using?VITEK32?system.?Metallo?β-lactamase?activity?was?determined?by?double-disc?synergy?test.?Amp?C?β-lactamase?activity?was?determined?by?Kirby-Bauer?disc?method.?OprD?protein?was?analyzed?by?sodium?dodecyl sulphate-polyacrylamide gel electrophoresis. PCR was performed to amplify gene oprD. The amplified products were subject?to?sequencing?analysis.?The?phylogenetic?relationship?was?determined?using?random?amplified?polymorphic?DNA?(RAPD)?method. Results Membrane protein OprD was analyzed in 7 clinical isolates of imipenem-intermediate P. aeruginosa. Two strains were devoid of OprD proteins and the corresponding oprD genes were found disrupted by the insertion element ISRP10 in the coding regions. Five strains had OprD proteins with different sizes. Sequence analysis showed that the peptides ranged from 427 to 443 amino acids. Multiple amino acid substitutions and / or deletions were found within the Loop 1 through Loop 8 of the OprD secondary structures. Conclusions ISRP10 inactivation and amino acid substitutions in oprD gene confer imipenem resistance in the clinical isolates of P. aeruginosa.

Saffold virus detection and epidemiological characteristics in children with acute respiratory infection or digestive tract infection in Tianjin / 天津医药

Objective To investigate prevalence and epidemiologic features of Saffold virus (SAFV) in hospitalized children with acute respiratory infection or digestive tract infection Tianjin area. Methods Nasopharyngeal aspirates from children with acute respiratory infection and fecal samples from children with digestive tract infection in Tianjin Children ’s Hospital were collected from January 2013 to December 2013. Viral nucleic acid was extracted, and SAFV infection was determined by using real-time quantitative PCR. Positive PCR products were sequenced. The sequencing results were aligned with known gene sequences of SAFV sequences in GenBank. The positive viral infection rate of nasopharyngeal aspirates and fecal samples, viral positive constituent ratio and positive detection rate in different age groups, seasonal distribution of SAFV infection were calculated. Other common respiratory tract or digestive tract viruses were also detected. Results Fourty-three (11.9%) nasopharyngeal aspirates from children with acute respiratory infection tested positive for SAFV. There was no significant difference between male and female infected children (aged between 6 d and 12 years old). The 79%(34/43) of the patients with SAFV infection aged under 1 year old. The infection most occurred in summer and winter. The 63 (16.4%) fecal samples from children with digestive tract infection tested positive for SAFV. There was significant difference between male and female infected children (aged between 5 h and 11 years old). SAFV infection was found to be year round. There was no significant difference in different age groups of nasopharyngeal aspirates and fecal samples. The mixed infection rate with SAFV and other respiratory tract or digestive tract viruses were 7.0%(3/43)and 12.7%(8/63), respectively. Conclusion Infection of SAFV had occurred in children with acute respiratory infection or digestive tract infection in Tianjin. SAFV has high detection rate in these children and is more common in children aged under 1 year old. The data suggest that some of acute respiratory infection or digestive tract infections in pediatric patients are related to SAFV. The Clinical doctors should pay attention to them .

Production of β-carotene by metabolically engineered Saccharomyces cerevisiae / 生物工程学报

β-carotene has a wide range of application in food, pharmaceutical and cosmetic industries. For microbial production of β-carotene in Saccharomyces cerevisiae, the supply of geranylgeranyl diphosphate (GGPP) was firstly increased in S. cerevisiae BY4742 to obtain strain BY4742-T2 through over-expressing truncated 3-hydroxy-3-methylglutaryl-CoA reductase (tHMGR), which is the major rate-limiting enzyme in the mevalonate (MVA) pathway, and GGPP synthase (GGPS), which is a key enzyme in the diterpenoid synthetic pathway. The β-carotene synthetic genes of Pantoea agglomerans and Xanthophyllomyces dendrorhous were further integrated into strain BY4742-T2 for comparing β-carotene production. Over-expression of tHMGR and GGPS genes led to 26.0-fold increase of β-carotene production. In addition, genes from X. dendrorhous was more efficient than those from P. agglomerans for β-carotene production in S. cerevisiae. Strain BW02 was obtained which produced 1.56 mg/g (dry cell weight) β-carotene, which could be used further for constructing cell factories for β-carotene production.

Biochemical characterization and substrate profile of a highly enantioselective carbonyl reductase from Pichia pastoris / 生物工程学报

Carbonyl reductases catalyze carbonyl compounds to chiral alcohols that are important building blocks in fine chemical industry. To study carbonyl reductase from Pichia pastoris GS115 (ppcr), we discovered a new gene (ppcr) encoding an NADPH-dependent carbonyl reductase by genomic data mining. It was amplified by PCR from the genomic DNA, and expressed in Escherichia coli BL21 (DE3). The recombinant protein was purified to homogeneity. The optimum temperature was 37 degrees C and the optimum pH of PPCR was 6.0. PPCR was stable below 45 degrees C. The Km and k(cat) value of the enzyme for ethyl 3-methyl-2-oxobutanoate were 9.48 mmol/L and 0.12 s, respectively. The enzyme had broad substrate specificity and high enantioselectivity. It catalyzed the reduction of aldehydes, a-ketoesters, beta-ketoesters and aryl ketones to give the corresponding alcohols with >97% ee with only a few exceptions, showing its application potential in the synthesis of chiral alcohols.

Isolation and classification of the bacteriophages of Pseudomonas aeruginosa and their application on biofilm control / 中华微生物学和免疫学杂志

Objective To isolate and classigy the bacteriophages specific to Pseudomonas aetuginosa and to investigate biofilm control efficaey of the isolated virulent phages.Methods With P. aeruginosa clinical strains as indicators.bacteriophages were isolated by screening difierent environmental samples.Classification of the isolated phages was done with the methods of restriction fragment analysis of phage genome and host range analysis.Transmission electron microscopy(TEM)was used in phage morphology study.In biogilm control tests,TJC729 was used as the jndicator strain to study the biofilm control efficacy of the isolated phages.Results Total 13 lytic phages specific to P.aeruginosa strains were isolated and named as C1-C13.According to the result of restriction fragment analysis.all 13 phages were double-stranded DNA viruses and could be divided into eight groups.Host range experiments were conducted with 5 laboratory strains and 12 clinical strains of P. aeruginosa.The same infection profiles were observed among phage C1 and C13,C6 and C7,and C9 and C11,respectively.While the remaining 7 phages each had different unique infection profile.Phage C1 was selected randomly to study its morphology.The obtained images showed that phage C1 had an icosahedral head with a non-contractile tail,belonging to the Siphoviridae family.Compared with the single phage,phage cocktail had the best effect on biofilm control.Further experiment results showed that phage C1.C10 and C12 can destroy biofilm after treatment of the biofilm for 24 h.The biofilm amounts were deceased to 32.7%,57.6%and 32.8%of the initial values,respectively.Conclusion Thirteen virulent phages specific to P. aeruginosa had been isolated.The phages could significantly inhibit the biofilm formation and had a certain degree of damage on the biofilm.The results suggested an alternative method for the treatments of P.aeruginosa infections.

Correlation between McNamara cephalometric analysis values and craniomaxillary linear parameters in Chongqing adolescents with normal occlusion / 第二军医大学学报

Objective:To establish the normal value of McNamara cephalometric analysis in Chongqing adolescents with normal occlusion and to obtain its regression models. Methods:Fifty five Chongqing adolescents with normal occlusion (male 27 and female 28)were taken lateral cephalograms. McNamara analysis was conducted and the correlation analysis was carried out.Results: There were significant differences in the normal values of McNamara analysis between male and female Chongqing adolescents, namely the effective maxillary length, effective mandibular length, lower anterior facial height and A Np line. There were no significant differences in Pog Np line, upper incisor to point A vertical,lower incisor to A P line.There were correlations between the effective maxillary length and effective mandibular length, effective mandibular length and lower anterior facial height, A Np line and Pog Np line, respectively.When effective mandibular length was fixed,lower anterior facial height and Pog Np line was correlated.The regression models were obtained.Conclusion:There is correlation between the linear measurements of the cephalometrics values.