16S rDNA-based molecular profiles of circulating bacteria in patients with severe acute pancreatitis / 肠外与肠内营养

Objective:This study aims to characterize the bacterial profile presenting in peripheral blood of severe acute pancreatitis (SAP) patients and investigate the potential role of circulating microorganisms in the development of systemic infection.Methods:A total of 30 patients with SAP were recruited in this study and divided into three groups:infected,sepsis and Septic shock (n =10 for each group).The peripheral blood was collected sterilely for extraction of DNA,which was subsequently amplified using the universe primers targeted the V6-V8 region of 16S ribosomal RNA genes.The amplicons were separated by denaturing gradient gel electrophoresis (DGGE),and then the gels were stained and photographed.The bands were cut out and sequenced to determine the closest bacterial relatives.Results:As shown in DGGE profile,multiple DNA bands (3 to 8 bands) were detected in peripheral blood from all (100％) of SAP patients complicated with septic shock.The microorganisms most frequently presenting in the blood of these cases included Escherichia coli,Bacillus coagulans,Pseudomonas putida,Pseudomonas aeruginosa,and Klebsiella pneumonia,with an incidence of 40 ％ or higher.In patients with sepsis,bacterial DNA consisting of 2 to 4 bands was observed in 90％ of the blood samples.The most common bacterial species was Pseudomonas putida (60％),followed by Shigella flexneri (40％),Staphylococcus aureus (30％) and Enterococcusfaecium (20％).By contrast,the positive rate of blood bacterial DNA was relatively lower in infected patients (70 ％).Of them,single bacterial species was commonly found in the blood samples.Conclusions:Our data showed that the bacterial profiles presenting in peripheral blood are distinct among SAP patients with different manifestations.Polymicrobial translocation could contribute to the development of systemic infection,offering novel insights into the pathogenesis of sepsis in SAE The findings are helpful for the prevention and treatment for bacterial infection and complications of SAP.

Expression of Helicoverpa armigera Cathepsin B in Pichia pastoris / 中国生物工程杂志

Cathepsin B from Helicoverpa armigera (HCB) belongs to the group of cysteine proteinases. HCB is proved being involved in the degradation of yolk proteins during embryonic development,which is an acidic preferring enzyme and is resistant to SDS. The expression of the proenzyme may offer a model for investigating the activation of the enzyme. The HCB gene was constructed into pPIC9K and expressed in Pichia pastoris KM71 strain . After induction by methanol, HCB was expressed and secreted into the medium. The molecular weight of the recombinant procathepsin B was determined as about 38 kDa. The expressed product was confirmed to be HCB by immunoblotting assay using specific rabbit anti-HCB polyclonal antibody. The activity of the product was assayed by in situ hydrolysis (gelatin-SDS-PAGE). These results showed that HCB with proteolytic activity was expressed in P. pastoris KM71. This proenzyme can be used for further research on the activation of the proenzyme or industrial production.