Navegando por Palavras-chave "cell adherence"

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    Genotypic and phenotypic characterization of enterotoxigenic Escherichia coli (ETEC) strains isolated in Rio de Janeiro city, Brazil
    (Elsevier B.V., 2004-03-08) Regua-Mangia, Adriana Hamond; Guth, Beatriz Ernestina Cabilio [UNIFESP]; Andrade, João Ramos da Costa; Irino, Kinue; Pacheco, Ana Beatriz Furlanetto; Ferreira, Luís Carlos de Souza; Zahner, Viviane; Teixeira, Lúcia Martins; Fdn Oowaldo Cruz; Universidade Federal do Rio de Janeiro (UFRJ); Universidade Federal de São Paulo (UNIFESP); Universidade do Estado do Rio de Janeiro (UERJ); Inst Adolfo Lutz Registro; Fdn Oswaldo Cruz
    Enterotoxigenic Escherichia coli (ETEC) strains have been implicated as important etiological agents of diarrheal disease, especially in developing countries. This group of microorganisms has been associated with a diverse range of genotypic and phenotypic markers. in the present study, 21 ETEC isolates previously defined according to the toxigenic genotypes, were characterized on the basis of O:H typing, cell adherence patterns, and colonization factors (CFs) antigens. Genetic diversity was investigated by random amplification polymorphic DNA (RAPD-PCR), pulsed-field gel electrophoresis (PFGE) and multilocus enzyme electrophoresis (MLEE). LT-I probe-positive isolates belonged to serotypes ONT:HNT, O7:H24, 048:H21, 088:H25, O148:H28, O159:H17 and 0159:H21. ST-h probe-positive isolates belonged to serotypes O159: H17, O148: H28 and O6:H-. Serotypes O148: H28, O159: H17 and O6:H- were associated with the CS6, CFA/I and CS1 CS3 antigens, respectively. Most ETEC strains exhibited a diffuse pattern of adherence to cultured epithelial cells. in general, phenotypic and genotypic characteristics correlated well. RAPD-PCR, PFGE and MLEE showed reproducibility and good discriminatory potential. the application of molecular typing systems allowed the detection of significant diversity among the isolates,. indicating a non-clonal origin and revealing intra-serotype variation overlooked by classical epidemiological approaches. the phenotypic and genotypic diversity observed lead us to recommend the use of different typing systems in order to elucidate the epidemiology of ETEC infection. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
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    Transient resistance to B16F10 melanoma growth and metastasis in CD43-/- mice
    (Lippincott Williams & Wilkins, 2002-02-01) Fuzii, H. T.; Travassos, L. R.; Universidade Federal de São Paulo (UNIFESP)
    CD43, the major transmembrane sialoglycoprotein of neutrophils, monocytes, T lymphocytes and platelets, is highly glycosylated and its high sialic acid content contributes to the strongly negative charge of cells. in this study the role of CD43 in melanoma development was addressed using CD43-/- mice (null mutated for the corresponding gene or knockout [KO]). Growth of B16F10 melanoma was retarded in the KO mice compared with the wild-type CD43+/+ control (WT). A marked difference in lung colonization and other metastatic foci was observed in the KO and WT mice up to 15 days after intravenous injection of tumour cells. the Initial resistance of KO mice was reversed with time, and in the long term there was no difference in the survival rate of the two animal groups. Transient resistance was attributed to increased adhesion of thrombin-activated platelets and leukocytes to melanoma and endothelial cells in KO mice. in the KO mice tumour emboli were found in the central portion of the lung more than at the lung periphery Immediately after intravenous Injection, in contrast to the WT mice. Activation of melanoma adhesion receptors by thrombin or TRAP stimulated lung colonization in WT but not KO mice. Therefore the correlation of tumour embolism and metastasis in short-term experiments depends on the nature and stability of interactions between the tumour and the blood/endothelial cells of the host. (C) 2002 Lippincott Williams Wilkins.