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Actinomyces Viscosus

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S R Fernandez – One of the best experts on this subject based on the ideXlab platform.

  • isolation of a neuraminidase gene from Actinomyces Viscosus t14v
    Applied and Environmental Microbiology, 1991
    Co-Authors: M K Yeung, S R Fernandez
    Abstract:

    A genomic library of Actinomyces Viscosus T14V DNA in lambda gt11 was screened for expression of neuraminidase activities. Four recombinant clones were detected that gave blue fluorescence upon incubation with a fluorogenic substrate, 2′-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid. Of these, two were identical, and all of the neuraminidase-positive clones shared a common 3.4-kbp DNA region. Expression of the enzyme activities in Escherichia coli carrying the cloned DNA was independent of the lacZ promoter of the vector. Maxicell analysis revealed that the 3.4-kbp DNA insert directed synthesis of a protein with an apparent molecular mass of 100,000 Da. The protein from cell extracts of E. coli clones migrated as a single band that stained for enzyme activity after electrophoresis in a nondissociating polyacrylamide gel. Moreover, human erythrocytes incubated previously with cell lysates from neuraminidase-positive E. coli were hemagglutinated by Actinomyces spp. The enzyme expressed by E. coli was active on substrates containing alpha-2,3 and alpha-2,6 ketosidic linked sialyl residues. Similar substrate specificities were obtained for both the extracellular and cell-associated neuraminidases from A. Viscosus T14V. The 3.4-kbp insert hybridized to DNA fragments in a Southern blot containing A. Viscosus T14V chromosomal DNA that had been digested with various restriction endonucleases. Data from hybridization studies show that A. Viscosus T14V contains a single copy of the neuraminidase gene.

M K Yeung – One of the best experts on this subject based on the ideXlab platform.

  • isolation of a neuraminidase gene from Actinomyces Viscosus t14v
    Applied and Environmental Microbiology, 1991
    Co-Authors: M K Yeung, S R Fernandez
    Abstract:

    A genomic library of Actinomyces Viscosus T14V DNA in lambda gt11 was screened for expression of neuraminidase activities. Four recombinant clones were detected that gave blue fluorescence upon incubation with a fluorogenic substrate, 2′-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid. Of these, two were identical, and all of the neuraminidase-positive clones shared a common 3.4-kbp DNA region. Expression of the enzyme activities in Escherichia coli carrying the cloned DNA was independent of the lacZ promoter of the vector. Maxicell analysis revealed that the 3.4-kbp DNA insert directed synthesis of a protein with an apparent molecular mass of 100,000 Da. The protein from cell extracts of E. coli clones migrated as a single band that stained for enzyme activity after electrophoresis in a nondissociating polyacrylamide gel. Moreover, human erythrocytes incubated previously with cell lysates from neuraminidase-positive E. coli were hemagglutinated by Actinomyces spp. The enzyme expressed by E. coli was active on substrates containing alpha-2,3 and alpha-2,6 ketosidic linked sialyl residues. Similar substrate specificities were obtained for both the extracellular and cell-associated neuraminidases from A. Viscosus T14V. The 3.4-kbp insert hybridized to DNA fragments in a Southern blot containing A. Viscosus T14V chromosomal DNA that had been digested with various restriction endonucleases. Data from hybridization studies show that A. Viscosus T14V contains a single copy of the neuraminidase gene.

Takeshi Igarashi – One of the best experts on this subject based on the ideXlab platform.

Sun Yu-liang – One of the best experts on this subject based on the ideXlab platform.

Eri Shimada – One of the best experts on this subject based on the ideXlab platform.

  • Lipoproteins of Actinomyces Viscosus induce inflammatory responses through TLR2 in human gingival epithelial cells and macrophages
    Microbes and infection, 2012
    Co-Authors: Eri Shimada, Hideo Kataoka, Yasushi Miyazawa, Matsuo Yamamoto, Takeshi Igarashi
    Abstract:

    Actinomyces Viscosus has been suggested to be associated with periodontal disease. However, the pathogenicity of this bacterium is not known. In this study, we examined inflammation-inducing activity by A. Viscosus. Whole cells and a lipophilic fraction of A. Viscosus ATCC19246 induced production of interleukin-8 and tumor necrosis factor alpha from both human oral epithelial cells and human monocytoid cells. This cytokine production was blocked by lipoprotein lipase treatment of the lipophilic fraction. In addition, anti-Toll-like receptor 2 antibody blocked the cytokine production. These results suggest that lipoprotein of A. Viscosus triggers inflammatory responses in periodontitis by activation of Toll-like receptor 2.