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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 110 (1992), S. 75-81 
    ISSN: 1573-4919
    Keywords: pristane ; tumor promoter ; cAMP response element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Pristane is a naturally occurring isoprenoid which is believed to be derived from the phytyl moiety of chlorophyll. Thus it is not surprising that pristane is present in many common fruits or vegetables and furthermore can be detected in tissues of fish and mammals. Using the rat as an animal model, pristane can function as a potent tumor promoter. It is conceivable that pristane could play a role in the development of certain malignancies in higher mammals since it is commonly found in the diet. At the molecular level, pristane can induce changes in the plasma membrane, alter the conformation of chromatin, as well as selectively activate gene expression. This study was undertaken to identify specific transcriptional motifs which are responsive to pristane. A transcriptional promoter which contained a cAMP response element (CRE) was consistently stimulated by pristane in several mouse and primate cell lines. A promoter construct which contained a single copy of the TPA response element (TRE) was also activated by pristane but surprisingly a promoter which contained multiple copies of the TRE was not. Activation of the TRE required 10 fold higher concentrations of pristane relative to activation of the CRE. Within two hours after addition of pristane to monkey fibroblasts (CV-1) levels of cAMP were increased more than two fold relative to controls. These data indicated that pristane can increase the level of cAMP in CV-1 cells and consequently stimulate transcriptional promoters which contain a CRE.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-4986
    Keywords: colon ; histochemistry ; lectins ; rectum ; ulcerative colitis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ulcerative colitis is an idiopathic chronic inflammatory condition of the large bowel associated with åbnormalities of mucin synthesis and secretion. In the present study, glycans were identified in 45 formalin-fixed, paraffin-embedded tissue samples from patients with ulcerative colitis. The tissue samples represented a spectrum of inflammation from chronic quiescent disease to severe inflammation. Thirteen biotinylated lectins, directed against a range of sialyl, fucosyl andN-acetylgalactosaminyl sequences, were applied using an avidin-peroxidase revealing system. The results were assessed semiquantitatively for a number of cellular sites. The expression of all sialyl sequences was increased in absorptive cells and in goblet cells and the expression of α2–6-linked sialyl sequences was enhanced in proportion to the degree of inflammation, while α2–3-linked sialyl sequences were diminished in more severe inflammation. The binding ofN-acetylgalactosaminyl-directed lectins was increased in the Golgi apparatus, while there was a reduction in the expression of α-fucosyl sequences in severe degrees of inflammation. This suggests that there is an increased biosynthetic rate for sialyl residues in all stages of disease with a reduction in α2–3-linked sialyl and fucosyl sequences in severe inflammation, and a shift from storedN-acetylgalactosaminyl sequences in goblet cells to an earlier form in the Golgi apparatus. The changes in sialyl sequences are a feature of ulcerative colitis even in quiescent disease and may be related to its aetiology and early pathogenesis, while most of the other changes reflect the severity of the disease and are probably part of its later pathogenesis or of induced reactive changes.
    Type of Medium: Electronic Resource
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