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  • 1
    Electronic Resource
    Electronic Resource
    Cardiac mitochondrial complex activity is enhanced by heat shock proteins (2003)
    Oxford, UK : Blackwell Science Pty
    Clinical and experimental pharmacology and physiology 30 (2003), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. Prolonged ischaemia and reperfusion in heart transplantation results in mitochondrial dysfunction and loss of cardio-energetics. Improved myocardial tolerance to ischaemia–reperfusion can be increased by de novo synthesis of heat shock protein (Hsp) groups, transiently expressed following mild hyperthermic or oxidative stress. Consideration of the roles of various Hsp in ischaemic–reperfused myocardium can provide new insights into potential therapeutic adjuncts to cardiac surgery.2. Several Hsp classes have been located within or in association with mitochondrial elements. Cardiac Hsp research has focused primarily on the 70 kDa group, involved in protein folding functions within the cytosol and matrix. Similarly, Hsp 60 and 10 have been shown to form a mitochondrial chaperonin complex conferring protection to ischaemia-challenged myocytes. Equally pertinent is Hsp 32, an isoform of the haem-metabolizing enzyme heme oxygenase.3. Our studies have shown that mitochondrial respiratory enzyme activity can be protected by Hsp, affording protection to cardiac energetics during preservation for transplantation. Upregulation of Hsp 32, 60 and 72 in rats, achieved by mild hyperthermic stress, improved cardiac function, ultrastructure and mitochondrial respiratory and complex activities in ex vivo perfused hearts subjected to cold cardioplegic arrest and ischaemia–reperfusion. Pre-ischaemic mitochondrial complex activities were increased in heat stress versus sham-treated groups for complex I, IV and V.4. Investigation of the direct effect of upregulation of Hsp 72 by gene transfection resulted in a similar pattern of response, with increased complex I activity and improved ventricular function.5. These studies provide the first evidence of Hsp-mediated enhancement of mitochondrial energetic capacity. Enhanced protection of mitochondrial energetics, as a result of increased Hsp expression, contributes to the recovery of myocardial function in ischaemia–reperfusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1440-1681.2003.03799.x
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  • 2
    Electronic Resource
    Electronic Resource
    DNA binding, adduct characterisation and metabolic activation of aflatoxin B1 catalysed by isolated rat liver parenchymal, Kupffer and endothelial cells (1991)
    Springer
    Archives of toxicology 65 (1991), S. 633-639 
    Details
    ISSN: 1432-0738
    Keywords: Aflatoxin B1 ; Parenchymal cells ; Nonparenchymal cells ; Mutagenicity ; DNA binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In vitro studies with rat liver parenchymal, Kupffer and endothelial cells isolated from male Sprague-Dawley rats were undertaken to investigate cell-specific bioactivation of aflatoxin B1, DNA binding and adduct formation. In the mutagenicity studies, using homogenates of all three separated liver cell populations (co-incubated with NADP+ and glucose-6-phosphate as cofactors for the cytochrome P-450 monooxygenase system) parenchymal, Kupffer and endothelial cells were able to activate aflatoxin B1 to a metabolite mutagenic to Salmonella typhimurium TA 98. In the case of nonparenchymal cells (i.e. Kupffer and endothelial cells) 10-fold higher concentrations of aflatoxin B1 had to be used to obtain a similar number of revertants to that observed with parenchymal cells. Induction studies with Aroclor 1254 led to a striking decrease in the activation of aflatoxin B1 in parenchymal cells, whereas nonparenchymal cells had a slightly enhanced metabolic activation capacity for aflatoxin B1. Metabolism studies with microsomes from induced and noninduced cells using testosterone as substrate revealed comparable results: after induction with Aroclor 1254, parenchymal cells showed a 60% decrease in the formation rate of 2α-hydroxytestosterone, whereas the formation rate of this metabolite remained unchanged in nonparenchymal cells; 2α-hydroxytestosterone is specifically formed by cytochrome P-450 IIC11, which also catalyses the activation of aflatoxin B1 to its epoxide. When freshly isolated, intact cells were incubated with tritiated aflatoxin B1, a dose-dependent aflatoxin B1 binding to DNA in parenchymal and nonparenchymal cells was observed. HPLC analysis of DNA acid hydrolysates of all three cell types showed the major adduct to be 8,9-dihydro-8-(N7-guanyl)-9-hydroxyaflatoxin B1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02098028
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    Paper (German National Licenses)
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