Identification and characterization of a salivary-pellicle-binding peptide by phage display

Objective

Dental biofilms are associated with oral diseases, making their control necessary. One way to control them is to prevent initial bacterial adherence to the salivary pellicle and thereby eventually decrease binding of late colonizing potential pathogens. The goal of this study was to generate a salivary-pellicle-binding peptide (SPBP) with antifouling activity towards primary colonizing bacteria. In order to achieve this goal we aimed to: (i) identify novel SPBPs by phage display; (ii) characterize the binding and antifouling properties of the selected SPBPs.

Methods

A library of 2 × 10⁹ phages displaying a random sequence of 12-mer peptides was used to identify peptides that bound selectively to the in vitro salivary pellicle. Three rounds of panning resulted in the selection of 10 pellicle-binding phages, each displaying a novel peptide sequence. The peptides were synthesized and their binding to the in vitro salivary pellicle was characterized in the presence and absence of calcium ions and Tween-20. The antifouling property of hydroxyapatite (HA) and saliva-coated HA discs treated with and without SPBPs were evaluated against Streptococcus gordonii.

Results

Ten unique SPBPs were identified using the phage display. One of these peptides, SPBP 10 (NSAAVRAYSPPS), exhibited significant binding to the in vitro salivary pellicle which was neither influenced by calcium ions, nor affected by up to 0.5% Tween-20. Its antifouling property against S. gordonii was significantly higher on the treated surfaces than on untreated surfaces.

Conclusions

Use of the phage display library enabled us to find a specific SPBP with antifouling property towards S. gordonii.     

多层螺旋CT扫描和三维重建在骨折的应用价值

目的 探讨多层螺旋CT二维多平面重建和三维表面遮盖成像在骨折中的应用价值。方法 对40例骨折患行多排螺旋CT扫描后二维多平面重建和三维表现遮盖成像。结果 40例患共计34例骨折。二维多平面重建和三维表现遮盖成像能更直观的显示骨折的具体情况。结论 CT二维、三维图像重建对于骨折的显示各有优缺点，两应结合使用。     

A novel transducible chimeric phage from Escherichia coli O157:H7 Sakai strain encoding Stx1 production

Shiga toxin-producing Escherichia coli (STEC), and especially enterohaemorrhagic E. coli (EHEC) are important, highly virulent zoonotic and food-borne pathogens. The genes encoding their key virulence factors, the Shiga toxins, are distributed by converting bacteriophages, the Stx phages. In this study we isolated a new type of inducible Stx phage carrying the stx1 gene cluster from the prototypic EHEC O157:H7 Sakai strain. The phage showed Podoviridae morphology, and was capable of converting the E. coli K-12 MG1655 strain to Shiga toxin-producing phenotype. The majority of the phage genes originate from the stx2-encoding Sakai prophage Sp5, with major rearrangements in its genome. Beside certain minor recombinations, the genomic region originally containing the stx2 genes in Sp5 was replaced by a region containing six open reading frames from prophage Sp15 including stx1 genes. The rearranged genome, together with the carriage of stx1 genes, the morphology and the capability of lysogenic conversion represent a new type of recombinant Stx1 converting phage from the Sakai strain.     

视频终端尺寸对儿童视疲劳的影响

 目的 探讨视频终端尺寸对儿童视疲劳的影响。方法 选取儿童30名为研究对象,年龄8~13岁,所有受检者在相同条件下,每人均通过手机、平板和电视3种视频终端观看2节20 min的课程视频,比较观看后的视力、瞬目次数及Schirmer试验数据。结果 (1)观看课程视频后,3种终端双眼视力较测前(右眼5.00±0.00,左眼5.00±0.00)均有所下降(P<0.05),手机组(右眼4.90±0.05,左眼4.86±0.07)低于电视组(右眼4.98±0.02,左眼4.94±0.05),差异有统计学意义(P<0.05)。(2)观看视频35 min时,各组瞬目次数较基础值(12.10±0.88)显著增加,其中手机组(22.80±1.48)高于平板组(19.70±2.06)和电视组(17.10±1.52),差异有统计学意义(P<0.05)。(3) Schirmer试验显示,观看视频后,各组双眼泪液分泌量较基础[右眼(12.30±1.06)mm,左眼(12.30±1.49)mm]明显增加,其中手机组[右眼(20.40±1.84)mm,左眼(20.70±2.45) mm]多于平板组[右眼(17.40±1.17)mm,左眼(17.70±2.00)mm]和电视组[右眼(15.30±0.82)mm,左眼(15.60±1.58)mm],差异有统计学意义(P<0.05)。结论 儿童使用视频设备后会产生视疲劳,屏幕较小的视频终端比大屏幕终端引发的视疲劳症状更重。     

Effects of movement imitation training in Parkinson's disease: A virtual reality pilot study

BackgroundHypometria is a clinical motor sign in Parkinson's disease. Its origin likely emerges from basal ganglia dysfunction, leading to an impaired control of inhibitory intracortical motor circuits. Some neurorehabilitation approaches include movement imitation training; besides the effects of motor practice, there might be a benefit due to observation and imitation of un-altered movement patterns. In this sense, virtual reality facilitates the process by customizing motor-patterns to be observed and imitated.ObjectiveTo evaluate the effect of a motor-imitation therapy focused on hypometria in Parkinson's disease using virtual reality.MethodsWe carried out a randomized controlled pilot-study. Sixteen patients were randomly assigned in experimental and control groups. Groups underwent 4-weeks of training based on finger-tapping with the dominant hand, in which imitation was the differential factor (only the experimental group imitated). We evaluated self-paced movement features and cortico-spinal excitability (recruitment curves and silent periods in both hemispheres) before, immediately after, and two weeks after the training period.ResultsMovement amplitude increased significantly after the therapy in the experimental group for the trained and un-trained hands. Motor thresholds and silent periods evaluated with transcranial magnetic stimulation were differently modified by training in the two groups; although the changes in the input–output recruitment were similar.ConclusionsThis pilot study suggests that movement imitation therapy enhances the effect of motor practice in patients with Parkinson's disease; imitation-training might be helpful for reducing hypometria in these patients. These results must be clarified in future larger trials.     

Surface display of a borrelial lipoprotein on meningococcal outer membrane vesicles

Outer Membrane Vesicles (OMVs) are gaining attention as vaccine candidates. The successful expression of heterologous antigens in OMVs, with the OMV functioning both as adjuvant and delivery vehicle, has greatly enhanced their vaccine potential. Since there are indications that surface exposed antigens might induce a superior immune response, targeting of heterologous antigens to the OMV surface is of special interest. Several systems for surface display of heterologous antigens on OMVs have been developed. However, these systems have not been used to display lipidated membrane-associated proteins known as lipoproteins, which are emerging as key targets for protective immunity. We were therefore interested to see whether we could express a foreign lipoprotein on the outer surface of OMVs. When outer surface protein A (OspA), a borrelial surface-exposed lipoprotein, was expressed in meningococci, it was found that although OspA was present in OMVs, it was no longer surface-exposed. Therefore, a set of fusions of OspA to different regions of factor H binding protein (fHbp), a meningococcal surface-exposed lipoprotein, were designed and tested for their surface-exposure. An N-terminal part of fHbp was found to be necessary for the successful surface display of OspA on meningococcal OMVs. When mice were immunized with this set of OMVs, an OspA-specific antibody response was only elicited by OMVs with clearly surface-exposed OspA, strengthening the idea that the exact positioning of an antigen in the OMV affects the immune response. This method for the surface display of heterologous lipoproteins on OMVs is a step forward in the development of OMVs as a vaccine platform.     

Humanized-VHH Transbodies that Inhibit HCV Protease and Replication

There is a need for safe and broadly effective anti-HCV agents that can cope with genetic multiplicity and mutations of the virus. In this study, humanized-camel V_HHs to genotype 3a HCV serine protease were produced and were linked molecularly to a cell penetrating peptide, penetratin (PEN). Human hepatic (Huh7) cells transfected with the JFH-1 RNA of HCV genotype 2a and treated with the cell penetrable nanobodies (transbodies) had a marked reduction of the HCV RNA intracellularly and in their culture fluids, less HCV foci inside the cells and less amounts of HCV core antigen in culture supernatants compared with the infected cells cultured in the medium alone. The PEN-V_HH-treated-transfected cells also had up-regulation of the genes coding for the host innate immune response (TRIF, TRAF3, IRF3, IL-28B and IFN-β), indicating that the cell penetrable nanobodies rescued the host innate immune response from the HCV mediated-suppression. Computerized intermolecular docking revealed that the V_HHs bound to residues of the protease catalytic triad, oxyanion loop and/or the NS3 N-terminal portion important for non-covalent binding of the NS4A protease cofactor protein. The so-produced transbodies have high potential for testing further as a candidate for safe, broadly effective and virus mutation tolerable anti-HCV agents.     

Humanized anti-VEGFR-2 ScFv-As2O3-stealth nanoparticles,an antibody conjugate with potent and selective anti-hepatocellular carcinoma activity

Low sensitivity of tumor tissue, targeting and sustained release of the drug are bottlenecks of the effect of chemotherapy on hepatocellular carcinoma. In this study, we used the ribosome display technology to screen human anti-VEGFR 2-single-chain antibody (ScFv) that could target directly to VEGFR2, and nanotechnology to prepare As2O3-nanoparticles. Then we built anti-VEGFR-2ScFv-As2O3-stealth nanoparticles using molecular coupling technology, which significantly increased anti-tumor effect while reducing toxicity. The in vivo tissue targeting distribution and anti-tumor effects of the anti-VEGFR-2 ScFv-As2O3-stealth nanoparticles were investigated. Our results showed that anti-VEGFR-2 ScFv-As2O3-stealth nanoparticles could inhibit the development of liver cancer xenograft as a targeting agent and also significantly inhibit angiogenesis.