Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-2307
    Keywords: Yersinia enterocolitica ; Peyer's patches ; Ultrastructure ; M-cell ; Invasiveness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Yersinia enterocolitica is an invasive pathogen capable of causing a wide spectrum of gastrointestinal diseases in man. While there is a considerable body of data on the invasiveness ofY. enterocolitica in vitro, little is known about the events in vivo leading to the translocation of the bacteria from the intestinal lumen into the ileal tissue. There is no detailed ultrastructural information describing the course of infection of pathogenicY. enterocolitica in comparison with an avirulent strain. We compared a virulent plasmid-bearing strain and an isogenic avirulent plasmid-free derivative strain ofY. enterocolitica serotype O∶8 at the ultrastructural level, in the established model of murine yersiniosis. At 12 h postinoculation we found no indications of an active invasion of the intestinal epithelium, although microcolonies of the pathogenic strain were detectable closely under the follicle-associated epithelium of the Peyer's patches. The plasmid-bearing strain ofY. enterocolitica affected the gut-associated lymphoid tissue which was destroyed 36 h post-infection. Unlike the pathogenic strain ofY. enterocolitica, the nonpathogenic plasmid-free strain caused no detectable morphological alterations in the ileal tissue by this time. Morphological evidence is provided thatYersinia does not invade the ileal epithelium in an active manner, as has been observed in vitro, but appears to be transported across the epithelial barrier by M-cells.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-2013
    Keywords: Key words Mucin secretion ; Colon cells ; HT-29/B6 cells ; Cholera toxin ; Carbachol ; Compound exocytosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Cholinergic stimulation triggers the secretion of apically stored, preformed mucin from goblet cells but the pathway of cAMP-stimulated mucin secretion is not known. In this study the effect of cholera toxin on mucin secretion in the human colonic goblet cell line HT-29/B6 was investigated and compared to the action of carbachol. PAS staining of mucin blotted onto nitrocellulose served to quantify the secretion of total mucin. Metabolic labelling was used to evaluate the secretion of newly synthesized mucin. The mucinous nature of the detected material was confirmed with an immunoblot employing a well-characterized polyclonal antibody reacting with MUC2-mucin. Cholera toxin caused a 116-fold increase of intracellular cAMP and strongly stimulated the secretion of both preformed and newly synthesized mucin for more than 20 h. Carbachol only triggered the release of preformed mucin immediately after addition. The secretory response to cholera toxin could be partly inhibited by the protein kinase A inhibitor H8 and the microtubule inhibitor colchicine. The action of carbachol was not affected by these agents. In conclusion, we demonstrate a direct cAMP-dependent effect of cholera toxin on mucin secretion by intestinal goblet cells. In contrast to carbachol, the action of cholera toxin involves de novo synthesis of mucin molecules and microtubule-mediated secretion. There seem to be distinct secretion pathways for muscarinic or cAMP-dependent stimulation of mucin secretion.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...