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  • 1
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Catalytic activity and immunoreactivity of glycogen phosphorylase were studied in pre- and postnatal rat brain. The catalytic activity was assayed in brain homogenates; immunoreactivity was investigated by immunoblot analysis using a monoclonal anti-bovine brain glycogen phosphorylase antibody. The cellular localization and intensity of immunoreactivity were analysed on paraffin-embedded sections utilizing the same monoclonal antibody. The catalytic activity increased 10-fold from embryonic day 16 to adult; immunoreactivity became detectable on embryonic day 16 and increased in intensity as the enzyme activity rose to adult values. The first cellular elements to be stained immunohistochemically were ependymal cells lining the ventricles, ependymal cells of the choroid plexus, meningeal cells and a selected population of neurons in the brain stem. The immunoreactivity of plexus cells and meningeal cells was reduced or absent in the adult rat brain. The earliest appearance of glycogen phosphorylase immunoreactivity in astroglial cells was seen at postnatal day 9 in the hippocampus. The staining pattern of the adult brain was reached at day 22 post partum. The developmental changes in glycogen deposition and in glycogen phophorylase activity and immunoreactivity may indicate a variable physiological role of glycogen metabolism for different cell types in the pre- and postnatal periods.
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  • 2
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunofluorescence double-labelling and immunoenzyme double-staining methods were used to examine the location of glycogen phosphorylase brain isozyme with the astrocyte markers glial fibrillary acidic protein (GFAP) and S-100 protein in formaldehydefixed, paraffin-embedded slices from adult rat brain. Astrocytes in the cerebellum and the hippocampus, which express GFAP or S-100 protein immunoreactivity, show glycogen phosphorylase immunoreactivity. Regional intensity and intracellular distribution of the three antigens vary characteristically. In ependymal cells, glycogen phosphorylase immunoreactivity is co-localized with S-100 protein immunoreactivity, but not with GFAP immunoreactivity. These findings confirm that glycogen phosphorylase in the rat brain is exclusively localized in astrocytes and ependymal cells. All astrocytes, as far as they express GFAP or S-100 protein, do contain glycogen phosphorylase.
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  • 3
    ISSN: 1432-0533
    Keywords: Multidrug resistance ; P-glycoprotein ; Glial tumor ; Immunohistochemistry ; RNA analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The most consistantly reported alteration of multidrug-resistant carcinoma cells is the overexpression of a membrane glycoprotein, termed P-glycoprotein. In this study we examined whether the strong intrinsic chemotherapy resistance of glial tumors might be related to the expression of the MDR1 gene which codes for P-glycoprotein. Fourteen glial tumors were examined immunohistochemically using the monoclonal antibody C219. In addition, RNA samples of 11 of these tumors were analysed using a sensitive Northern blot assay. P-glycoprotein is expressed in all 14 glial tumors; the number of stained tumor cells, however, varied considerably ranging from 0.3% to 15%. There was no correlation between the number of MDR1-positive cells and the histological malignancy. Varying amounts of MDR1 mRNA were detectable in 7 from 11 examined tumors. The results of our study show that the MDR1 gene is expressed in human glial tumors and suggest that the multidrug transporter may contribute to the clinical non-responsiveness of these tumors to chemotherapy.
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  • 4
    ISSN: 1432-0533
    Keywords: Multidrug resistance ; Glial tumors ; Transforming growth factor type β ; Bone morphogenetic protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The multidrug transporting cell membrane molecule P-glycoprotein can be spontaneously expressed in human glioma cells. Transcripts of mdr genes were detected in glial tumor cells by polymerase chain reaction and Northern blotting, expression of P-glycoprotein was analyzed by immunocytochemistry and functional activity by cytofluorometry of fluorescent probe transport. In vitro treatment of glioma cells with vincristine induced coordinate over-expression of both mdr1 and mdr3 genes associated with very high P-glycoprotein-mediated multidrug transport, resistant to the inhibitory activity of chemosensitizers like verapamil. The physiological modulators of multidrug transport are as yet unknown. We therefore initiated a screening program to analyze the effects of cytokines on multidrug transport. We observed, that transforming growth factors β1, -β2, and β1.2-but not the related bone morphogenetic protein (BMP) 2-inhibited multidrug transport. Interestingly, BMP 2 antagonized the TGF-β induced inhibition of multidrug transport.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 86 (1993), S. 393-396 
    ISSN: 1432-0533
    Keywords: Multiple sclerosis ; Creutzfeldt-Jakob discase ; Intercrines ; Interleukin-8
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Expression of cytokine genes regulating vascular permeability and chemoattraction was studies by polymerase chain reaction in RNA from two different types of brain lesions: a multiple sclerosis plaque and in tissue from a patient with Creutzfeldt-Jakob disease. While cytokine genes encoding vascular permeability factor, interleukin (IL)-2, IL-4, or IL-10, generally associated with active inflammatory processes, were not expressed, we observed expression of some intercrine genes in both types of lesions. As these lesions share a common set of structural features such as prominent astrogliosis and glial cells are known producers of intercrines, we suggest that intercrines have a role in the formation of gliotic brain lesions.
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