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  • alloxan-diabetes  (2)
  • toxicity  (2)
  • Springer  (4)
  • American Geophysical Union (AGU)
  • American Institute of Physics
  • 1995-1999  (2)
  • 1990-1994  (2)
  • 1960-1964
  • 1905-1909
Collection
Publisher
  • Springer  (4)
  • American Geophysical Union (AGU)
  • American Institute of Physics
Years
  • 1995-1999  (2)
  • 1990-1994  (2)
  • 1960-1964
  • 1905-1909
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 117 (1992), S. 63-70 
    ISSN: 1573-4919
    Keywords: glycogen phosphorylase ; alloxan-diabetes ; cardiomyocytes ; G-protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The basis for the hypersensitive response of glycogen phosphorylase to epinephrine stimulation was investigated in adult rat cardiomyocytes isolated from normal and alloxan-diabetic animals. To assess potential G-protein involvement in the response, normal and diabetic derived myocytes were incubated with either cholera or pertussis toxin prior to hormonal stimulation. Pretreatment of cardiomyocytes with cholera toxin resulted in a potentiated response to epinephrine stimulation whereas pertussis toxin did not affect the activation of this signaling pathway. To determine if the enhanced response of phosphorylase activation resulted from an alteration in adenylate cyclase activation, the cells were challenged with forskolin. After 3 hr in primary culture, diabetic cardiomyocytes exhibited a hypersensitive response to forskolin stimulation relative to normal cells. However, after 24 hr in culture, both normal and diabetic myocytes responded identically to forskolin challenge. The present data suggest that a cholera toxin sensitive G-protein mediates the hypersensitive response of glycogen phosphorylase to catecholamine stimulation in diabetic cardiomyocytes and this response which is present in alloxan-diabetic cells and is induced in vitro in normal cardiomyocytes is primarily due to a defect at a post-receptor site.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 145 (1995), S. 131-139 
    ISSN: 1573-4919
    Keywords: glycogen phosphorylase ; alloxan-diabetes ; cardiomyocytes ; cGMP ; phosphodiesterase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The focus of this study was to identify the molecular basis for the hypersensitive response of glycogen phosphorylase activation to epinephrine stimulation in alloxan diabetic-derived cardiomyocytes. Cyclic AMP levels were found not to be significantly different between normal and diabetic-derived cells while cGMP concentrations were found consistently to be significantly lower in diabetic-derived cells than in normal cells. Treatment with cyclic GMP analogues did not affect phosphorylase activation by epinephrine in normal cardiomyocytes whereas, IBMX, a nonselective phosphodiesterase inhibitor, had a significant effect on basal and agonist-stimulated phosphorylase activity in both normal and diabetic-derived cardiomyocytes. Differences in the time course for the rate of decay of phosphorylasea from agonist-stimulated to basal levels were observed between normal and diabetic cells. After 3 h in primary culture, phosphorylasea activity returned to basal levels more quickly in normal than in diabetic-derived cells while after 24 h in culture, the time for phosphorylasea decay was not significantly different between normal and diabetic myocytes and was longer than the 3 h response. After 3 h in primary culture, no significant difference in phosphorylase kinase activity was observed between normal and diabetic-derived cells exposed to epinephrine whereas, after 24 h in culture, phosphorylase kinase activity was significantly decreased in diabetic cells under basal and agonist-stimulated conditions. These data collectively suggest that the hypersensitive response of glycogen phosphorylase to epinephrine stimulation in diabetic-derived cardiomyocytes is not due to a defect present at the level of phosphorylase kinase but may, in part, result from an alteration in cardiac phosphodiesterase activity resulting from diminished intracellular cyclic GMP concentrations.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 134 (1991), S. 167-178 
    ISSN: 1573-5036
    Keywords: Al3+ ; aluminium ; hydroxy-aluminium ; phytotoxicity ; polynuclear aluminium ; rhizotoxicity ; roots ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aluminium (III) released from soil minerals to the soil solution under acid conditions may appear as hexaaquaaluminium (Al(H2O)6 3+, or Al3+ for convenience) or may react with available ligands to form additional chemical species. That one or more of these species is rhizotoxic (inhibitory to root elongation) has been known for many decades, but the identity of the toxic species remains problematical for the following reasons. 1. Several Al species coexist in solution so individual species cannot be investigated in isolation, even in artificial culture media. 2. The activities of individual species must be calculated from equilibrium data that may be uncertain. 3. The unexpected or undetected appearance of the extremely toxic triskaidekaaluminium (AlO4Al12(OH)24(H2O)12 7+ or Al13) may cause misatribution of toxicity to other species, especially to mononuclear hydroxy-Al. 4. If H+ ameliorates Al3+ toxicity, or vice versa, then mononuclear hydroxy-Al may appear to be toxic when it is not. 5. The identity and activities of the Al species contacting the cell surfaces are uncertain because of the H+ currents through the root surface and because of surface charges. This article considers the implications of these problems for good experimental designs and critically evaluates current information regarding the relative toxicities of selected Al species. It is concluded that polycationic Al (charge 〉2) is rhizotoxic as are other polyvalent cations.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 173 (1995), S. 329-335 
    ISSN: 1573-5036
    Keywords: calcium sulfite ; flue gas desulfurization residue ; oxidation ; sulfur dioxide ; toxicity ; Triticum aestivum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract CaSO3 is a by-product formed by several of the processes used for scrubbing SO2 from flue gas produced by coal-burning power generators. Using CaSO3 to improve the calcium status of acid soils would be a beneficial alternative to disposal in landfills. CaSO3 has biocidal properties and is used as a disinfectant and food and drink preservative. It is important to evaluate under what conditions application to soils would not harm plant growth. Laboratory experiments confirmed that two transformations of CaSO3 occurred in soil systems: (1) decomposition to produce SO2 gas, and (2) oxidation to calcium sulfate. Conversion to SO2 occurred in solution and soil at low pH, and acid soils treated with CaSO3 were initially toxic to seedling root growth. The degree of toxicity was time-dependent, with reduction in toxicity occurring as CaSO3 oxidized to calcium sulfate. Soil reaction also influenced toxicity, and at soil pH levels above 6, little seedling toxicity was evident.
    Type of Medium: Electronic Resource
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