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  • 1
    ISSN: 1432-0428
    Keywords: Na+-coupled glucose transporter ; facilitative glucose transporters ; mesangial cells ; glomerulopathy ; phlorizin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Since previous studies from our laboratory have demonstrated that increased glucose consumption by cultured rat mesangial cells is accompanied by an accelerated production of type IV and type VI collagen, we have now examined the manner by which glucose is transported into these cells. A progressive stimulation of glucose uptake by the mesangial cells was observed with increasing concentrations of NaCl so that at 145 mmol/l about twice as much glucose entered the cells as in its absence (substituted by choline chloride). Moreover, since phlorizin inhibited the NaCl-promoted uptake of glucose and this salt was found to increase the accumulation of α-methylglucoside in a manner which could not be duplicated by KCl or mannitol, both Na+-coupled and facilitative glucose transporters appeared to be present in the cells. Km values of 1.93 mmol/l and 1.36 mmol/l were determined for the co-transport and facilitated transport pathways, respectively, with their Vmax being 29.5 and 18.0 nmol·mg protein−1· h−1. Both uptake activities were found to be down-regulated by exposure of the cells to high glucose and furthermore the Na+-dependent transport could no longer be detected after about 12 passages of the cells. Hybridization of mesangial cell mRNA with cDNA probes revealed transcripts for the Na+/glucose co-transporter as well as GLUT1 and to a lesser extent GLUT4. The identification of the co-transporter in these non-polarized cells is pertinent to an understanding of the intracellular signals which can lead to the development of the diabetic glomerular lesions; in the hyperglycaemic state this carrier provides an additional route for accelerated glucose entry and furthermore by the attendant increase in Na+ flux may bring about an alteration in the ionic composition of the cell.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cancer chemotherapy and pharmacology 41 (1997), S. 210-216 
    ISSN: 1432-0843
    Keywords: Key words Alkylphosphocholines ; HL-60 cells ; U-937 cells ; K-562 cells ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Alkylphosphocholines (APC) represent a new group of ether-lipid-related compounds with remarkable activity against transformed cells in vitro and good tolerability in vivo. Their mechanism of action remains unknown. The aim of the present study was to investigate the effects of a series of APC on three human leukemic cell lines: K-562, HL-60, and U-937. The tetrazolium dye-reduction (MTT) assay and cell counting were used to determine the cytotoxicity of the APC used. DNA gel electrophoresis and enzyme-linked immunosorbent assay (ELISA) detection of oligonucleosomes were performed to identify and quantify DNA fragmentation. Electron and phase-contrast microscopy were used to detect morphologic changes specific for programmed cell death. HL-60 and U-937 cells were found to be sensitive, but K-562 cells were relatively resistant to APC exposure. APC with long alkyl chains exerted stronger cytotoxicity than did those with short alkyl chains. DNA fragmentation was found after treatment with APC in HL-60 and U-937 cells but not in K-562 cells. In HL-60 cells the increase in mono- and oligonucleosome formation as measured by ELISA was correlated with the length of the alkyl chains at 14 h of exposure to APC but plateaued at 20 h. The morphologic alterations in HL-60 and U-937 cell lines, such as cell shrinkage, chromatin condensation, and formation of apoptotic bodies, confirmed the induction of apoptosis after APC exposure. It is concluded that programmed cell death plays an important role in the cytotoxicity of APC against certain human leukemic cell lines. The antineoplastic profiles of APC with long alkyl chains render them attractive for further therapeutic application.
    Type of Medium: Electronic Resource
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