Background: Bezlotoxumab is a neutralizing antibody targeting toxin B of Clostridium difficile. Results: The structure of bezlotoxumab bound to a fragment of toxin B reveals its epitopes and mechanism of neutralization. Conclusion: The epitopes overlap with two of the presumed carbohydrate binding pockets, preventing binding of the toxin to target host cells. Significance: The data provide a molecular basis for neutralization by this clinically important antibody.

Objectives:The potential of Escherichia coli (E. coli) isolated from inflammatory bowel disease (IBD) patients to damage the integrity of the intestinal epithelium was investigated.Methods:E. coli strains isolated from patients with ulcerative colitis (UC) and healthy controls were tested for virulence capacity by molecular techniques and cytotoxic assays and transepithelial electric resistance (TER). E. coli isolate p19A was selected, and deletion mutants were created for alpha-hemolysin (α-hemolysin) (hly) clusters and cytotoxic necrotizing factor type 1 (cnf1). Probiotic E. coli Nissle and pathogenic E. coli LF82 were used as controls.Results:E. coli strains from patients with active UC completely disrupted epithelial cell tight junctions shortly after inoculation. These strains belong to phylogenetic group B2 and are all α-hemolysin positive. In contrast, probiotic E. coli Nissle, pathogenic E. coli LF82, four E. coli from patients with inactive UC and three E. coli strains from healthy controls did not disrupt tight junctions. E. coli p19A WT as well as cnf1, and single loci of hly mutants from cluster I and II were all able to damage Caco-2 (Heterogeneous human epithelial colorectal adenocarcinoma) cell tight junctions. However, this phenotype was lost in a mutant with knockout (Δ) of both hly loci (P<0.001).Conclusions:UC-associated E. coli producing α-hemolysin can cause rapid loss of tight junction integrity in differentiated Caco-2 cell monolayers. This effect was abolished in a mutant unable to express α-hemolysin. These results suggest that high Hly expression may be a mechanism by which specific strains of E. coli pathobionts can contribute to epithelial barrier dysfunction and pathophysiology of disease in IBD.

Niobium-doped strontium titanate synthesized via conventional solid-state reaction has been studied. Influence of niobium content on the lattice parameters and electrical conductivity has been reported. Various reduction conditions have been investigated. For samples reduced in hydrogen at 1400°C, a transition from thermally activated to metallic behavior has been observed. Maximum electrical conductivity (ca. 55 Scm −1 at 650°C) has been observed for the SrTi 0.98 Nb 0.02 O 3-δ sample. The relation of electrical conductivity with the porosity of the samples has been shown.

We report the novel modification of a hydrogen-terminated polycrystalline boron-doped electrode with a microwave pulsed-plasma polymerized allylamine. Boron-doped diamond (BDD) was coated with a very thin layer of adherent cross-linked, pinhole- and additive-free allylamine plasma polymer (PPAAm) resistant to hydrolysis and delamination and characterized by a high density of positively charged amino groups. The pulsed microwave plasma was applied to improve the cross-linking degree and bonding of the plasma polymeric films to boron-doped diamond. The amine-treated BDD films were assessed by advanced surface analytical techniques, such as X-ray photoelectron spectroscopy (XPS), FT-IR, scanning electron microscopy (SEM), laser-induced fluorescence, and water contact angle measurements. The amine-modified Si/BDD surface was functionalized with selected organic molecules containing a carboxylic group in the presence of coupling agents such as diisopropylcarbodiimide (DIC). The anthraquinone derivatives Boc-Lys(AQ)–OH and peptide anthraquinone derivatives of dendrimers were used as electroactive agents for characterization by cyclic voltammetry (CV). The fluorescence reference standards Rhodamine 110 and Fmoc-Trp(Boc)–OH were selected for fluorescence studies.

In this study, we have demonstrated the fabrication of novel materials called boron-doped carbon nanowalls (B:CNWs), which are characterized by remarkable electrochemical properties such as high standard rate constant (k°), low peak-to-peak separation value (ΔE) for the oxidation and reduction processes of the [Fe(CN)] redox system, and low surface resistivity. The B:CNW samples were deposited by the microwave plasma-assisted chemical vapor deposition (CVD) using a gas mixture of H/CH/BH and N. Growth results in sharp-edged, flat, and long CNWs rich in sp as well as sp hybridized phases. The achieved high values of k° (1.1 × 10 cm s) and ΔE (85 mV) are much lower compared to those of the glassy carbon or undoped CNWs. The enhanced electrochemical performance of the B:CNW electrode facilitates the simultaneous detection of DNA purine bases: adenine and guanine. Both separated oxidation peaks for the independent determination of guanine and adenine were observed by means of cyclic voltammetry or differential pulse voltammetry. It is worth noting that the determined sensitivities and the current densities were about 1 order of magnitude higher than those registered by other electrodes.

Titanium dioxide nanotubes gain considerable attention as a photoactive material due to chemical stability, photocorrosion resistance, or low-cost manufacturing method. This work presents scalable pulsed laser modification of TiO2 nanotubes resulting in enhanced photoactivity in a system equipped with a motorized table, which allows for modifications of both precisely selected and any-large sample area. Images obtained from scanning electron microscopy along with Raman and UV–vis spectra of laser-treated samples in a good agreement indicate the presence of additional laser-induced shallow states within band gap via degradation of crystalline structure. However, X-ray photoelectron spectroscopy spectra revealed no change of chemical nature of the modified sample surface. Photoelectrochemical measurements demonstrate superior photoresponse of laser-treated samples up to 1.45-fold for an energy beam fluence of 40 mJ/cm2 compared to that of calcined one. According to the obtained results, optimal processing parameters were captured. Mott–Schottky analysis obtained from impedance measurements indicates an enormous (over an order of magnitude) increase of donor density along with a +0.74 V positive shift of flat band potential. Such changes in electronic structure are most likely responsible for enhanced photoactivity. Thus, the elaborated method of laser nanostructuring can be successfully employed to the large-scale modification of titania nanotubes resulting in their superior photoactivity. According to that, the results of our work provide a contribution to wider applications of materials based on titania nanotubes.

The paper discusses the synthesis and performance of iodine doped titania nanotube arrays exhibited under irradiation.

BackgroundThe use of food-grade Lactic Acid Bacteria (LAB) as DNA delivery vehicles represents an attractive strategy to deliver DNA vaccines at the mucosal surfaces as they are generally regarded as safe (GRAS). We previously showed that either native Lactococcus lactis (LL) or recombinant invasive LL expressing Fibronectin Binding Protein A of Staphylococcus aureus (LL-FnBPA+) or Internalin A of Listeria monocytogenes (LL-InlA+), were able to deliver and trigger DNA expression by epithelial cells, either in vitro or in vivo. InlA does not bind to its receptor, the murine E-cadherin, thus limiting the use of LL-InlA+ in in vivo murine models. Moreover, FnBPA binds to its receptors, integrins, via fibronectin introducing another limiting factor. In order to avoid the limitations of LL-InlA+ and LL-FnBPA+, a new L. lactis strain was engineered to produce a previously described mutated form of InlA (LL-mInlA+) allowing the binding of mInlA on murine E-cadherin.ResultsAfter showing the expression of mInLA at the surface of LL-mInlA+ strain, in vitro gentamycin survival assay in Caco-2 cells showed that LL-mInlA+ is 1000 times more invasive than LL. LL-mInlA+ invasivity was also validated by fluorescence microscopy. LL and LL-mInlA+ were transformed with pValacBLG, a plasmid containing the cDNA of bovine β-Lactoglobulin (BLG), resulting in strains LL-BLG and LL-mInlA+BLG. The plasmid transfer in vitro using LL-mInlA+BLG was increased 10 times compared to LL-BLG. Moreover, the number of mice producing BLG in isolated enterocytes after oral administration of LL-mInlA+BLG in vivo was slightly higher than after oral administration of LL-BLG.ConclusionsWe confirmed in this study that the production of mInlA at the surface of L. lactis is a promising strategy for plasmid transfer in vitro and in vivo.