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  • 1
    Electronic Resource
    Electronic Resource
    Possible role of free radicals generated by pseudohypoxia in the regulation of hepatic glucose output. An in vitro model using rat liver microsomal glucose 6-phosphatase (1997)
    Springer
    Diabetologia 40 (1997), S. 1251-1254 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Free radical ; hepatic glucose output ; glucose 6-phosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Hepatic glucose output is decreased by hyperglycaemia through an unknown mechanism. We hypothesize that free radicals generated by hyperglycaemic pseudohypoxia might cause glucose output to decrease by inhibiting glucose 6-phosphatase – a key enzyme of gluconeogenesis. To prove this a model experiment was performed on a microsome fraction of rat liver. One of the characteristic features of pseudohypoxia due to hyperglycaemia is an increase in the ratio of NADH/NAD + , so in the present study the changes in NADH – induced glucose 6-phosphatase activity were investigated as related to the release of inorganic phosphate (Pi) derived from glucose 6-phosphate. After incubation for 50 min, Pi release was significantly reduced by NADH (4.026 ± 0.189 vs 2.696 ± 0.429 μmol · l–1· mg protein–1, control vs NADH samples, p 〈 0.01). The decrease in the activity of glucose 6-phosphatase generated by NADH was prevented by using desferrioxamine, an irreversible ferric chelator, butylated hydroxytoluene and Trolox, two agents which inhibit lipid peroxidation, and reduced glutathione, a non-specific radical scavanger. Superoxide dismutase, catalase and the hydroxyl radical scavenger dimethyl sulphoxide proved to be ineffective. When the above investigations were carried out in the presence of a ferric-EDTA complex the inhibition of glucose 6-phosphatase was found to be inducible by hydrogen peroxide and/or hydroxyl free radicals. These investigations seem to indicate that pseudohypoxia due to hyperglycaemia can inhibit the activity of glucose 6-phosphatase both by lipid peroxidation and by inducing hydrogen peroxide and/or hydroxyl free radicals and thus it may play a part in the glucose-induced decrease of hepatic glucose output. [Diabetologia (1997) 40: 1251–1254]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250050817
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  • 2
    Electronic Resource
    Electronic Resource
    Are insulin resistance and atherosclerosis the consequences of oxidative stress? (1996)
    Springer
    Diabetologia 39 (1996), S. 1002-1003 
    Details
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403924
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  • 3
    Electronic Resource
    Electronic Resource
    Immunorecognition, ultrastructure and phosphorylation status of astrocytic gap junctions and connexin43 in rat brain after cerebral focal ischaemia (1998)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 10 (1998), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Gap junctions between astrocytes support a functional syncytium that is thought to play an important role in neural homeostasis. In order to investigate regulation of this syncytium and of connexin43 (Cx43), a principal astrocytic gap junction protein, we determined the sequelae of gap junction and Cx43 disposition in a rat cerebral focal ischaemia model with various ischaemia/reperfusion times using sequence-specific anti-Cx43 antibodies (designated 13-8300, 18A, 16A and 71-0700) that exhibit differential recognition of Cx43, perhaps reflecting functional aspects of gap junctions. Antibody 13-8300 specifically detects only an unphosphorylated form of Cx43 in both Western blots and tissue sections. In hypothalamus after brief (15 min) ischaemic injury, Cx43 at intact gap junctions undergoes dephosphorylation, accompanied by reduced epitope recognition by antibodies 16A and 71-0700. Tissue examined 24 h after reperfusion showed that these effects were reversible. Astrocytic gap junction internalization occurring 1 h after ischaemia was accompanied by decreased immunodetection with 13-8300. At this time, gap junctions were absent in the ischaemic core, coinciding with a loss of Cx43 recognition with 18A and 13-8300, but elevated labelling of internalized Cx43 with 16A and 71-0700. Unphosphorylated Cx43 persisted at intact gap junctions confined to a thin corridor at the ischaemic penumbra which contained presumptive apoptotic cell profiles. Similar results were obtained in ischaemic striatum and cerebral cortex, though with a delayed time course that depended on the severity of the ischaemic insult. These results demonstrate that astrocytic Cx43 epitope masking, dephosphorylation and cellular redistribution occur after ischaemic brain injury, proceed as a temporally and spatially ordered sequence of events and culminate in differential patterns of Cx43 modification and sequestration at the lesion centre and periphery. These observations suggest an attempt by astrocytes in the vicinity of injury to remodel the junctional syncytium according to altered tissue homeostatic requirements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.1998.00253.x
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  • 4
    Electronic Resource
    Electronic Resource
    Compression of the Pituitary Stalk Elicits Chronic Increases in CSF Vasopressin, Oxytocin as well as in Social Investigation and Aggressiveness (1996)
    Oxford : Blackwell Science Ltd.
    Journal of neuroendocrinology 8 (1996), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The neurochemical and behavioural effects of a novel stereotaxic surgical method developed for interrupting the nerve fibres running through the rat pituitary stalk to the posterior pituitary gland was studied. The cerebrospinal fluid (CSF) vasopressin (AVP) and oxytocin (OT) content as well as changes in aggressiveness were measured in rats one week and one month after the surgical intervention. The main results are as follows: (1) the compression of the pituitary stalk elicits a chronic increase in water consumption, as well as in CSF vasopressin and oxytocin content; (2) the surgical intervention increased the frequency of clinch fighting after one week. The increase in aggressiveness accentuated after one month and, in addition, operated animals showed reduced scores of resting while exploratory and social behaviours increased; (3) there was a strong positive correlation between water consumption, vasopressin, and aggressiveness; (4) oxytocin changes showed a positive correlation with variation in social behaviour. The surgical intervention may serve as a model for lesions of the pituitary stalk and formation of ectopic neurohypophyses in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2826.1996.04654.x
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  • 5
    Electronic Resource
    Electronic Resource
    The Synthesis of Levyne-Type Zeolite Studied by Thermal Analysis of Methylquinuclidine Aluminosilicate Gels (1998)
    Springer
    Journal of thermal analysis and calorimetry 54 (1998), S. 891-899 
    Details
    ISSN: 1572-8943
    Keywords: DSC ; DTG ; levynite ; TG ; thermal analysis ; QTMD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract DSC, TG and quadrupole mass spectrometer data concerning methylquinuclidinium iodide (MeQ1), dried precursor gel, and crystalline levyne-type zeolite are discussed together with the thermal degradation of MeQ1 mixed with single inorganic components of the gel. It is shown that MeQ+ions play a role in the organization of the gel structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010164508871
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Behaviour of Hydrotalcite and Its Fe (CN)64- Pillared Derivative on Heat Treatment (1999)
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 311-316 
    Details
    ISSN: 1572-8943
    Keywords: dehydration/rehydration and stability characterization ; Fe(CN)6 4- anion pillared layered double hydroxide ; Mg-Al layered double hydroxide ; thermal behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mg-Al L(ayered) D(ouble) H(ydroxide) was prepared and its thermal behaviour was characterized by thermoanalytical methods (TG, DTG, DTA), 27Al M(agic) A(ngle) S(pinning) NMR spectroscopy, X-ray diffractometry (XRD) and S(canning) E(lectron) M(icroscopy). Heat treatment destroyed the layered structure, which could only be partially reconstituted by rehydration. On calcination mixed oxide with the predominance of basic sites were formed. Pillaring the LDH with Fe(CN)6 4- anions was also performed. The material was characterized by XRD and BET measurements. Heat stability of the pillared substance was investigated, too. Pillaring proved to be successful, however, decreased heat resistance was found in the intercalated material relative to the guest LDH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010138314956
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