It is proposed that the genesis of extracellular membrane vesicles in Gram-negative bacteria is a result of cell wall turnover. Peptidoglycan turnover would cause a turgor on the outer membrane, causing the outer membrane to bulge and finally bleb. Mechanical motion would then shear the blebs into the culture medium.

Vaccinia virus complement control protein (VCP) has been shown to possess the ability to inhibit both classical and alternative complement pathway activation. The newly found ability of this protein to bind to heparin has been shown in previous studies to result in uptake by mast cells, possibly promoting tissue persistence. It has also been shown to reduce chemotactic migration of leukocytes by blocking chemokine binding. In addition, this study shows that VCP-through its ability to bind to glycosaminoglycans (heparin-like molecules) on the surface of human endothelial cells-is able to block antibody binding to surface major histocompatibility complex class I molecules. Since heparin binding is critical for many functions of this protein, we have attempted to characterize the molecular basis for this interaction. Segments of this protein, generated by genetic engineering of the DNA encoding VCP into the Pichia pastoris expression system, were used to localize the regions with heparin binding activity. These regions were then analyzed to more specifically define their properties for binding. It was found that the number of putative binding sites (K/R-X-K/R), the overall positive charge, and the percentage of positively charged amino acids within the protein were responsible for this interaction.

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ObjectivesTo evaluate sealing ability of root canals obturated with bioceramic-impregnated gutta percha cone (BCC) or gutta percha (GP), with bioceramic sealer (BCS) or AH Plus (AH; Dentsply-Maillefer), in roundly-prepared canals using matched single-cone technique, based on bacterial leakage test, and to analyze obturation quality using micro-computed tomography (CT) analysis.Materials and MethodsNinety-two distobuccal roots of maxillary molars were prepared using nickel-titanium files to apical size 40/0.06. The roots were divided into 4 groups (n = 20) that were obturated with a master cone and sealer: GP/AH, BCC/AH, GP/BCS, and BCC/BCS. Bacterial leakage model using Enterococcus faecalis was used to evaluate sealing ability for 60-day period. Obturated samples from each group (n = 4) were analyzed using micro-CT.ResultsAll groups showed bacterial leakage at 20%–45% of samples with mean leakage times of 42–52 days. There were no significant differences in bacterial leakage among the groups. Micro-CT showed minimal gaps and voids in all groups at less than 1%.ConclusionsIn roundly-prepared canals, the single cone obturation with BCC/BCS was comparable to GP/AH for bacterial leakage at 60 days.

Our results indicate the possibility of a worldwide prevalence of serotype k strains with properties in common with those of previously reported strains.

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Streptococcus mutans is one of the oral pathogens associated with infective endocarditis (IE).With respect to bacterial binding ability to the extracellular matrix, the Cnm protein, a cell surface collagen-binding adhesin of S. mutans, is known as one of the possible virulence factors with regard to IE. In this study, we aimed to determine the distribution of the cnm gene, which encodes Cnm, in a large number of clinical isolates of S. mutans from Thai subjects. Then, the cnm-positive strains were classified using a multilocus sequence typing (MLST) scheme, which we constructed previously. In addition, the data were analysed together with our previous MLST data of cnmpositive strains from Japan and Finland in order to evaluate the clonal relationship among S. mutans strains harbouring the cnm gene. The cnm gene was detected in 12.4 % of all 750 Thai isolates, and serotype f showed the highest rate of detection (54.5 %). According to the MLST data, two clonal complex groups were revealed as the important clones related to cnm-positive S. mutans from various origins of isolation. Moreover, the collagen-binding properties of S. mutans strains with the cnm gene were significantly greater than those of strains without the gene, although four cnm-negative strains classified into two sequence types (STs), ST110 and ST136, showed extremely high collagen-binding rates suggesting the presence of additional genes involved with collagen binding in these STs. Taken together, these results provided information on both epidemiological as well as evolutional aspects of S. mutans possessing the cnm gene. INTRODUCTIONStreptococcus mutans is a well-known pathogen of dental caries (Hamada & Slade, 1980), which consists of four serotypes, c, e, f and k (Linzer et al., 1986;). The detection rate of serotype c is highest among the strains isolated from oral cavities, followed by serotype e, while serotypes f and k are regarded as being present in minor proportions . Various pieces of evidence show the association of S. mutans with some life-threatening diseases such as infective endocarditis (IE), although the major species related to IE belong to the mitis group of oral streptococci (Banas, 2004;Mylonakis & Calderwood, 2001). Moreover, continuous detections of this bacterium in specimens from patients suffering from such disease emphasize the importance of S. mutans in IE (Gauduchon et al., 2001;Nomura et al., 2006;Vose et al., 1987;Ullman et al., 1988). Indeed, studies to clarify specific components involved in IE in S. mutans have also been performed worldwide (Beg et al., 2002;Jung et al., 2009; MatsumotoNakano et al., 2009;Miller-Torbert et al., 2008).IE is initiated by the binding of bacterial surface molecules to host extracellular matrix (ECM) proteins exposed on damaged heart tissue (Moreillon & Que, 2004). In S. mutans, collagen-binding adhesin or Cnm protein, encoded by the cnm gene, was reported as a strain-specific collagen-binding molecule (Sato et al., 2004). The Cnm protein possesses a collagen-binding domain (CBD) in ...

Gamma interferon (IFN-␥)-induced endothelial cells actively participate in initiating immune responses by interacting with CD4؉ T cells via class II major histocompatibility complex (