The Antimicrobial Effect of Silver Ion Impregnation into Endodontic Sealer against Streptococcus mutans.

Pulpal and periradicular diseases are primarily caused by bacterial invasion of the root canal system as a result of caries progression. The presence of residual bacteria at the time of root canal completion (obturation) is associated with significantly higher rate of treatment failure. Re-infection of obturated root canals can be potentially prevented by enhancing the antibacterial activities of root canal obturation materials. We evaluated, in an in vitro model, the antimicrobial efficacy of silver ions added to a common endodontic sealer. For that purpose we performed growth inhibition studies and bacterial viability tests. We measured the zone of inhibition, optical density and performed confocal laser scanning microscopy. Our results show that the silver ions enhance the antimicrobial activity of the root canal sealer against Streptococcus mutans. This study approach may hold promise for studying other biologically based therapies and therefore increasing the success rate of routine orthograde root canal treatment

The impact of horizontal gene transfer on the adaptive ability of the human oral microbiome.

The oral microbiome is composed of a multitude of different species of bacteria, each capable of occupying one or more of the many different niches found within the human oral cavity. This community exhibits many types of complex interactions which enable it to colonize and rapidly respond to changes in the environment in which they live. One of these interactions is the transfer, or acquisition, of DNA within this environment, either from co-resident bacterial species or from exogenous sources. Horizontal gene transfer in the oral cavity gives some of the resident bacteria the opportunity to sample a truly enormous metagenome affording them considerable adaptive potential which may be key to survival in such a varying environment. In this review the underlying mechanisms of HGT are discussed in relation to the oral microbiome with numerous examples described where the direct acquisition of exogenous DNA has contributed to the fitness of the bacterial host within the human oral cavity

Proteome Analysis Identifies the Dpr Protein of Streptococcus mutans as an Important Factor in the Presence of Early Streptococcal Colonizers of Tooth Surfaces

Oral streptococci are primary colonizers of tooth surfaces and Streptococcus mutans is the principal causative agent of dental caries in humans. A number of proteins are involved in the formation of monospecies biofilms by S. mutans. This study analyzed the protein expression profiles of S. mutans biofilms formed in the presence or absence of S. gordonii, a pioneer colonizer of the tooth surface, by two-dimensional gel electrophoresis (2-DE). After identifying S. mutans proteins by Mass spectrometric analysis, their expression in the presence of S. gordonii was analyzed. S. mutans was inoculated with or without S. gordonii DL1. The two species were compartmentalized using 0.2-μl Anopore membranes. The biofilms on polystyrene plates were harvested, and the solubilized proteins were separated by 2-DE. When S. mutans biofilms were formed in the presence of S. gordonii, the peroxide resistance protein Dpr of the former showed 4.3-fold increased expression compared to biofilms that developed in the absence of the pioneer colonizer. In addition, we performed a competition assay using S. mutans antioxidant protein mutants together with S. gordonii and other initial colonizers. Growth of the dpr-knockout S. mutans mutant was significantly inhibited by S. gordonii, as well as by S. sanguinis. Furthermore, a cell viability assay revealed that the viability of the dpr-defective mutant was significantly attenuated compared to the wild-type strain when co-cultured with S. gordonii. Therefore, these results suggest that Dpr might be one of the essential proteins for S. mutans survival on teeth in the presence of early colonizing oral streptococci

Altered serological and cellular reactivity to H-2 antigens after target cell infection with vaccinia virus

MICE generate cytotoxic T lymphocytes (CTL) which are able to lyse virus infected target cells in vitro after infection with lymphocytic choriomeningitis virus (LCMV) and pox-viruses1−3. CTL kill syngeneic and semiallogenic infected cells but not allogenic infected targets. Target cell lysis in these systems seems to be restricted by H-2 antigens, especially by the K or D end of the major histocompatibility complex (MHC). In experiments where virus specific sensitised lymphocytes kill virus infected allogenic target cells4 the effector lymphocytes have not been characterised exactly. Recent investigations suggest that the active cell in this assay, at least in the measles infection, is a non-thymus derived cell (H. Kreth, personal communication). An H-2 restriction of cell mediated cytolysis (CMC) to trinitrophenol (TNP)-modified lymphocytes has also been described5. Zinkernagel and Doherty6 postulated that the CTL is directed against syngeneic H-2 antigens and viral antigens and they suggested an alteration of H-2 induced by the LCMV infection. Earlier7 we found a close topological relationship between H-2 antigens and the target antigen(s) responsible for CMC in the vaccinia system. Here we report experiments which were carried out to prove alteration of H-2 after infection of L-929 fibroblasts with vaccinia virus

Identification of suitable controls for miRNA quantification in T-cells and whole blood cells in sepsis

Complex immune dysregulation is a hallmark of sepsis. The occurring phases of immunosuppression and hyperinflammation require rapid detection and close monitoring. Reliable tools to monitor patient's immune status are yet missing. Currently, microRNAs are being discussed as promising new biomarkers in sepsis. However, no suitable internal control for normalization of miRNA expression by qPCR has been validated so far, thus hampering their potential benefit. We here present the first evaluation of endogenous controls for miRNA analysis in human sepsis. Novel candidate reference miRNAs were identified via miRNA microArray. TaqMan qPCR assays were performed to evaluate these microRNAs in T-cells and whole blood cells of sepsis patients and healthy controls in two independent cohorts. In T-cells, U48 and miR-320 proved suitable as endogenous controls, while in whole blood cells, U44 and miR-942 provided best stability values for normalization of miRNA quantification. Commonly used snRNA U6 exhibited worst stability in all sample groups. The identified internal controls have been prospectively validated in independent cohorts. The critical importance of housekeeping gene selection is emphasized by exemplary quantification of imuno-miR-150 in sepsis patients. Use of appropriate internal controls could facilitate research on miRNA-based biomarker-use and might even improve treatment strategies in the future

Gross total but not incomplete resection of glioblastoma prolongs survival in the era of radiochemotherapy†

Background This prospective multicenter study assessed the prognostic influence of the extent of resection when compared with biopsy only in a contemporary patient population with newly diagnosed glioblastoma. Patients and methods Histology, O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status, and clinical data were centrally analyzed. Survival analyses were carried out with the Kaplan-Meier method. Prognostic factors were assessed with proportional hazard models. Results Of 345 patients, 273 underwent open tumor resection and 72 biopsies; 125 patients had gross total resections (GTRs) and 148, incomplete resections. Surgery-related morbidity was lower after biopsy (1.4% versus 12.1%, P = 0.007). 64.3% of patients received radiotherapy and chemotherapy (RT plus CT), 20.0% RT alone, 4.3% CT alone, and 11.3% best supportive care as an initial treatment. Patients ≤60 years with a Karnofsky performance score (KPS) of ≥90 were more likely to receive RT plus CT (P < 0.01). Median overall survival (OS) (progression free survival; PFS) ranged from 33.2 months (15 months) for patients with MGMT-methylated tumors after GTR and RT plus CT to 3.0 months (2.4 months) for biopsied patients receiving supportive care only. Favorable prognostic factors in multivariate analyses for OS were age ≤60 years [hazard ratio (HR) = 0.52; P < 0.001], preoperative KPS of ≥80 (HR = 0.55; P < 0.001), GTR (HR = 0.60; P = 0.003), MGMT promoter methylation (HR = 0.44; P < 0.001), and RT plus CT (HR = 0.18, P < 0.001); patients undergoing incomplete resection did not better than those receiving biopsy only (HR = 0.85; P = 0.31). Conclusions The value of incomplete resection remains questionable. If GTR cannot be safely achieved, biopsy only might be used as an alternative surgical strateg

Alterations to nuclear architecture and genome behavior in senescent cells.

The organization of the genome within interphase nuclei, and how it interacts with nuclear structures is important for the regulation of nuclear functions. Many of the studies researching the importance of genome organization and nuclear structure are performed in young, proliferating, and often transformed cells. These studies do not reveal anything about the nucleus or genome in nonproliferating cells, which may be relevant for the regulation of both proliferation and replicative senescence. Here, we provide an overview of what is known about the genome and nuclear structure in senescent cells. We review the evidence that nuclear structures, such as the nuclear lamina, nucleoli, the nuclear matrix, nuclear bodies (such as promyelocytic leukemia bodies), and nuclear morphology all become altered within growth-arrested or senescent cells. Specific alterations to the genome in senescent cells, as compared to young proliferating cells, are described, including aneuploidy, chromatin modifications, chromosome positioning, relocation of heterochromatin, and changes to telomeres

A Method for Structure–Activity Analysis of Quorum-Sensing Signaling Peptides from Naturally Transformable Streptococci

Many species of streptococci secrete and use a competence-stimulating peptide (CSP) to initiate quorum sensing for induction of genetic competence, bacteriocin production, and other activities. These signaling molecules are small, unmodified peptides that induce powerful strain-specific activity at nano-molar concentrations. This feature has provided an excellent opportunity to explore their structure–function relationships. However, CSP variants have also been identified in many species, and each specifically activates its cognate receptor. How such minor changes dramatically affect the specificity of these peptides remains unclear. Structure–activity analysis of these peptides may provide clues for understanding the specificity of signaling peptide–receptor interactions. Here, we use the Streptococcus mutans CSP as an example to describe methods of analyzing its structure–activity relationship. The methods described here may provide a platform for studying quorum-sensing signaling peptides of other naturally transformable streptococci