Chirality of the biomolecules enhanced its stereospecific action of dihydromyricetin enantiomers.

The present study explores the effect of chirality of the biological macromolecules, its functional aspects, and its interaction with other food components. Dihydromyricetin (DHM) is a natural novel flavonol isolated from the vine tea (Ampelopsis grossedentata) leaves. However, limited progress in enantiopure separation methods of such compounds hinder in the development of enantiopure functional studies. This study is an attempt to develop a simple, accurate, and sensitive extraction method for the separation of the enantiopure DHM from vine tea leaves. In addition, the identification and purity of the extracted enantiopure (-)-DHM were further determined by the proton nuclear magnetic resonance (1H-NMR) and the carbon nuclear magnetic resonance (13C-NMR). The study further evaluates the antimicrobial activity of isolated (-)-DHM in comparison with racemate (+)-DHM, against selected foodborne pathogens, whereas the action mode of enantiopure (-)-DHM to increase the integrity and permeability of the bacterial cell membrane was visualized by confocal laser scanning microscopy using green fluorescence nucleic acid dye (SYTO-9) and propidium iodide (PI). Moreover, the morphological changes in the bacterial cell structure were observed through field emission scanning electron microscope. During analyzing the cell morphology of B. cereus (AS11846), it was confirmed that enantiopure (-)-DHM could increase the cell permeability that leads to the released of internal cell constituents and, thus, causes cell death. Therefore, the present study provides an insight into the advancement of enantiopure isolation along with its antimicrobial effect which could be served as an effective approach of biosafety.

Research progress of veno-venous extracorporeal membrane oxygenation (VV-ECMO) in the treatment of adult severe respiratory failure / 中国胸心血管外科临床杂志

@#As an extracorporeal life support technology, veno-venous extracorporeal membrane oxygenation (VV-ECMO) has been demonstrated its role in the treatment of patients with severe respiratory failure. Its main advantages include the ability to maintain adequate oxygenation and remove excess CO2, increase oxygen delivery, improve tissue perfusion and metabolism, and implement lung protection strategies. Clinicians should accurately assess and identify the patient's condition, timely and accurately carry out VV-ECMO operation and management. This article will review the patient selection, cannulation strategy, anticoagulation, clinical management and weaning involved in the application of VV-ECMO.

Molecular mechanisms and molecular imaging evaluation of carotid vulnerable plaques / 国际脑血管病杂志

A variety of molecular imaging techniques based on the molecular mechanisms of vulnerable plaques, including positron emission tomography (PET) can identify the vulnerable plaque of the guilty carotid artery in cerebrovascular events and thus provide more detailed information for the risk assessment of stroke. This article reviews the molecular mechanisms and molecular imaging evaluation techniques of vulnerable carotid plaques.

Mining for sensitive and reliable species-specific primers for PCR for detection of Cronobacter sakazakii by a bioinformatics approach.

Although several studies have reported PCR assays for distinguishing Cronobacter sakazakii from other species in the genus, reports regarding assay sensitivity and specificity, as well as applications for food testing, are lacking. Hence, the objective of this study was to develop a sensitive and reliable PCR-based method for detection of C. sakazakii by screening for specific target genes. The genome sequence of C. sakazakii in the GenBank database was compared with that of other organisms using BLAST. Thirty-eight DNA fragments unique to C. sakazakii were identified, and primers targeting these sequences were designed. Finally, 3 primer sets (CS14, CS21, and CS38) were found to be specific for C. sakazakii by PCR verification. The detection limit of PCR assays using the 3 pairs of primers was 1.35 pg/µL, 135 fg/µL, and 135 fg/µL, respectively, for genomic DNA, and 5.5×10(5), 5.5×10(3), 5.5×10(3) cfu/mL, respectively, using pure cultures of the bacteria, compared with 13.5 pg/µLand 5.5×10(5) cfu/mLfor primer set SpeCronsaka, which has been previously described. Cronobacter sakazakii were detected in artificially contaminated powdered infant formula (PIF) by PCR using primer sets CS21 and CS38 after 8h of enrichment. The detection limit was 5.5×10(-1) cfu/10g of PIF. Thus, the PCR assay can be used for rapid and sensitive detection of C. sakazakii in PIF.

Breeding of high-producing LI-F lipopeptide Paenibacillus polymyxa by protoplast fusion and differential expression analysis of fusion strains / 生物工程学报

Auxotrophic strains of N1-37 (Phe-) and N2-27 (His-), screened from mutations of Paenibacillus polymyxa JSa-9 previously, were used as the parent strains to screen high-producing LI-F antibacterial lipopeptide fusion strain through protoplast fusion with polyethylene glycol as a promote agent. Fusion strain F5-15 was obtained. Then the product of LI-F antibacterial lipopeptide was quantified by HPLC, and the difference of expression of the key genes of lipopeptide synthase between wild strain JSa-9 and the fusion strain was analyzed by real-time PCR. LI-F antibacterial lipopeptide yield of the fusion strain F5-15 was 3.1-fold of the original strain JSa9's, and the expression levels of the target genes were 10.48, 2.48, 2.1 and 11.8 fold of the initial strain JSa-9, respectively.

Cloning and expression of lipoxygenase gene from Anabaena sp. PCC 7120 and purification, characterization of the recombinant enzyme / 生物工程学报

We cloned the lipoxygenase gene (ana-LOX) from Anabaena sp. PCC 7120 and expressed it in Escherichia coli BL21 (DE3) pLysS. We determined the active site of the recombinant ana-LOX through site-directed gene mutagenesis and obtained the shortest length of the functional gene. Meanwhile, we studied the properties of recombinant ana-LOX after purification. The C-terminal of the Aos (allene oxide synthase)-LOX fusion gene in Anabaena sp. PCC 7120 genome was found belonging to LOXs family by bioinformatics analysis. Further results of site-directed gene mutagenesis confirmed that the active sites of ana-LOX were His197, His202, His369, Asn373and Ile455. The shortest length of functional gene was identified to be 1 254 bp based on the strategy of shortening the gene length gradually. The highest activity of recombinant ana-LOX of 6 750 U/mL could be achieved when constructed to pET-32a vector and expressed at low temperature 16 degrees C. We purified the enzyme by Ni-NTA chelating affinity chromatography, with 60.89% yield and specific activity of 11.4 x 10(4) U/mg. The optimum reaction temperature and pH for ana-LOX were 45 degrees C and 6.0, respectively. Furthermore, the obtained ana-LOX was stable at room temperature. The effect of metal ions on ana-LOX was determined also. Fe2+, Mg2+ Ca2+ could markedly promote the activity of this enzyme whereas Fe3+ and Cu2+ had a strong inhibitory effect on it. Finally, the ana-LOX could improve the microscopical structure of dough. The results of this study will provide a basis for future improvements and food industrial applications of ana-LOX.

Correlation between food intolerance and Henoch-Sch(o)nlein purpura in children / 中华肾脏病杂志

Objective To investigate the correlation between food intolerance and Henoch-Sch(o)nlein purpura (HSP) in children and the efficacy of food forbidden or alternative therapy. Methods The levels of IgG against several common food in serum obtained from 40 children with HSP were measured by ELISA. The efficacy of food forbidden or alternative food therapy was assessed after 3 months. Results Total positive rate of serum food-intolerant IgG antibodies in HSP children was 92.5%. Among these 14 intolerant foods, the positive percentage of egg was the highest (33.8%), followed by tomato (14.9%), milk (13.5%) and morrhua (12.2%). Significant differences of the sort and degree of food intolerance existed among different age groups (t=2.257, P=0.045), but not between boys and girls (t=1.053, P=0.315), city and countryside (t= 1.388, P=0.193). There was no linear correlation between total food intolerance and serum IgG level (t=0.793, P=0.445). Food intolerance had no direct relation to immune complex deposition in kidneys of HSP nephritis (r =-0.262, P =0.387). The efficacy of adjusting diet was 95% . Conclusions HSP is closely related to food intolerance. Egg is the most common intolerant food. Food forbidden or alternative therapy shows acceptable efficacy in the treatment of most Henoch-Sch(o)nlein purpura children.

Fusion expression of fibrinolytic enzyme gene PPFE-I from endophytic Paenibacillus polymyxa in Escherichia coli and activity analysis / 生物工程学报

With the genomic DNA of strain EJS-3 as the template, we amplified the gene of fibrinolytic enzyme from Paenibacillus polymyxa (PPFE-I) by PCR. We purified the PCR product and ligated it into pMD19-T. After DNA sequencing, we cloned the PPFE-I gene into expression vector pET-DsbA and transformed it into Escherichia coli BL21(DE3). Upon induction of IPTG, we found that the activity of recombinant fibrinolytic enzyme fused with DsbA expressed in Escherichia coli was 228 IU/mL. SDS-PAGE analysis showed that the recombinant enzyme was soluble and accounted for about 18.4% of total cell protein. Western blotting demonstrated that the recombinant protein was DsbA-PPFE-I. We purified the recombinant enzyme by Ni affinity chromatography, thrombin digestion and sephadex G-100 gel-filtration, and identified the molecular weight of purified product to be 66.3 kDa with MALDI-TOF mass spectrometry. The purified enzyme exhibited distinct fibrinolytic activity on fibrin plate.

Cloning and expression of organic solvent tolerant lipase gene from Staphylococcus saprophyticus M36 / 生物工程学报

Lipases are important biocatalysts that are widely used in food processing and bio-diesel production. However, organic solvents could inactivate some lipases during applications. Therefore, the efficient cloning and expression of the organic solvent-tolerant lipase is important to its application. In this work, we first found out an organic solvent-tolerant lipase from Staphylococcus saprophyticus M36 and amplified the 741 bp Lipase gene lip3 (GenBank Accession No. FJ979867), by PCR, which encoded a 31.6 kD polypeptide of 247 amino acid residues. But the lipase shared 83% identity with tentative lip3 gene of Staphylococcus saprophyticus (GenBank Accession No. AP008934). We connected the gene with expression vector pET-DsbA, transformed it into Escherichia coli BL21 (DE3), and obtained the recombinant pET-DsbA-lip3. With the induction by 0.4 mmol/L of isopropyl beta-D-thiogalactopyranoside at pH 8.0, OD600 1.0, 25 degrees C for 12 h, the lipase activity reached up to 25.8 U/mL. The lipase expressed was stable in the presence of methanol, n-hexane, and isooctane, n-heptane.

Immobilization of yeast cells with polymeric carrier cross-linked using radiation technique.

Various compositions of 2-hydroxyethacrylate (HEA) and methoxy polyethylene glycol methacrylate (M23G) monomers were irradiated by gamma-rays at low temperature (-78 degrees C) to synthesize polymer carriers for effectively immobilizing yeast cells. The yeast cells were immobilized by cell adhesion onto/in these polymers. The ethanol productivity of immobilized yeast cells with the polymer carriers was higher than that of free cells, increasing by 1-3 times. However, the ethanol productivity of immobilized yeast with the polymer carrier resulting from 7%/7% (HEA/M23G) monomer was low, comparatively. The effect of adding cross-linking reagent (4G) to the low concentration of HEA/M23G monomers on the activity of yeast cells immobilized with the cross-linked carriers by radiation polymerization was investigated. The ethanol productivity of immobilized cells with the carriers, which were cross-linked by adding 3-6% 4G to the low concentration of HEA/M23G monomer, was increased by 20-30%, because the pore size, network structure, and mechanical strength of the polymer carriers was well adjusted and cell leakage from the polymer carriers decreased. The relationship between the ethanol productivity of immobilized yeast cells and the interior structure of polymer carriers is discussed and indicated that the interior structure of polymer carriers is crucial for effective immobilization of yeast cells.