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  • 1
    Electronic Resource
    Electronic Resource
    Absence of glucopenic inhibition of the insulin response to arginine at the onset of diabetes in BB/W rats (1988)
    Springer
    Diabetologia 31 (1988), S. 225-227 
    Details
    ISSN: 1432-0428
    Keywords: Glucopenia ; insulin ; glucagon ; arginine ; diabetes ; BB/W rats ; perfused pancreas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To determine if the inhibiting effect of glucopenia on arginine-stimulated insulin secretion is impaired at the onset of autoimmune diabetes, the insulin response to arginine was studied at 5.6 and 2.8 mmol/l glucose in perfused pancreata isolated from BB/W rats on the first day of diabetes and from age-matched diabetes-prone BB/W rats without diabetes. During glucopenia the baseline insulin secretion was reduced by more than 80% in both groups. However, the arginine-stimulated insulin response in the diabetic group was only 16.5% lower during glucopenia compared to 79.1% lower in the nondiabetic controls. Also, enhancement of the arginine-stimulated glucagon response by glucopenia was modest compared to controls. The results indicated that at the onset of this form of autoimmune diabetes the surviving B cells are, for unknown reasons, hyperresponsive to arginine and that, in contrast to the controls, this response is not inhibited by glucopenia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00290589
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Glucagon physiology and pathophysiology in the light of new advances (1985)
    Springer
    Diabetologia 28 (1985), S. 574-578 
    Details
    ISSN: 1432-0428
    Keywords: Glucagon ; diabetes ; noradrenaline ; insulin ; fructose-2,6-bisphosphate ; cyclic AMP-dependent protein kinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent advances in the understanding of glucagoninsulin relationships at the level of the islets of Langerhans and of hepatic fuel metabolism are reviewed and their impact on our understanding of glucagon physiology and pathophysiology is considered. It now appears that α cells can respond directly to hyperglycaemia in the absence of insulin and β cells, but that antecedent hyperglycaemia masks or attenuates this response. Insulin appears to exert ongoing release inhibition upon glucagon secretion, probably via the intra-islet microvascular system that connects β cells to α cells. Diabetic hyperglucagonemia in insulin deficient states appears to be secondary to lack of the restraining influence of insulin. The α cell response to glucopenia, by contrast, may be in large part mediated by release of noradrenaline from nerve endings in contact with α cells. Glucagon's action on glucose and ketone production by hepatocytes is mediated by increase in cyclic-AMP-dependent protein kinase. The opposing action of insulin upon glucagon-mediated events probably occurs largely at this level. Consequently, when glucagon secretion or action is blocked, cyclic-AMP-dependent protein kinase activity is low even in the absence of insulin, explaining why marked glucose and ketone production is absent in bihormonal deficiency states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00281991
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Homogeneous crystal nucleation in the poly(ethylene oxide)/poly(methyl methacrylate) system at low temperatures (1988)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 39 (1988), S. 257-260 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Relative Keimzahldichten der PEO-Kristallkeime wurden als Funktion von Temperatur (≦ 260 K) und Temperzeit aus nachfolgenden isothermen Kristallisationskurven (280 K) berechnet. Die Untersuchungen wurden mittels DSC an zwei Blends und einem Triblockcopolymer des Systems Poly(ethylenoxid)/Poly(methylmethacrylat) (anionisch synthetisiert, vorwiegend syndiotaktisches PMMA) durchgeführt. Die Ergebnisse werden im Zusammenhang mit dem frühen Stadium der Phasenentmischung im 10-nm-Bereich diskutiert. Eine schrittweise Änderung der relativen Keimzahldichten in einem Blend wird als schrittweise Änderung der (kleinen) kritischen Keimgröße als Funktion der Temperatur erklärt.
    Notes: Relative number densities of PEO crystal nuclei are calculated as a function of annealing temperature (≦ 260 K) and annealing time from subsequent isothermal (280 K) crystallization curves. These are obtained by DSC with two blends and one triblock copolymer of the poly(ethylene oxide)/poly(methyl methacrylate) (PEO/PMMA) system (which is anionically synthesized PMMA is mainly syndiotactic). The results are discussed in terms of the early stages of phase decomposition in the 10 nm range. A stepwise change of the nucleus number density in one blend is interpreted by a stepwise change of the (small) critical nucleus size as a function of temperature.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1988.010390511
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Crystallization and melting behaviour in block copolymers of poly(ethylene oxide) with amorphous components. The influence of compatibility (1991)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 42 (1991), S. 431-438 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mittels DSC-Untersuchungen wurden Zusammenhänge zwischen Kristallisations- (Tc) und Schmelztemperaturen (Tm) in Blockcopolymeren in Abhängigkeit von der Verträglichkeit der Copolymerkomponenten für die Kristallisation aus der Schmelze untersucht. Als Beispiel für ein verträgliches System wurde Poly(ethylenoxid) (PEO, kristallin)-Poly(methylmethacrylat) (PMMA, amorph) ausgewählt; das unverträgliche System ist PEO-Poly(tert.-butylmethacrylat) (PTBMA, amorph). Das Verträglichkeitsverhalten beider Systeme wird beschrieben. In Blockcopolymeren aus verträglichen Komponenten hängt Tc von der Zusammensetzung ab, jedoch ist Tc geringer als in vergleichbaren Blends. Ausreichende Kristallisationszeit vorausgesetzt, hängt Tm im wesentlichen nur von der PEO-Blockmolmasse ab. In Blockcopolymeren aus unverträglichen Komponenten werden sowohl Tc als auch Tm stark von den Blockmolmassen der Einzelkomponenten und den damit verbundenen PEO-Domänengrößen bestimmt. Es werden Tc-Tm-Diagramme vorgestellt und diskutiert.
    Notes: By means of DSC, connections between melt crystallization (Tc) and melting temperatures (Tm) of block copolymers have been studied as depending on the compatibility of the block copolymer components. As examples for a compatible and an incompatible system, the systems poly(ethylene oxide) (PEO, crystalline)-poly(methyl methacrylate) (PMMA, amorphous) and PEO/poly(tert.-butyl methacrylate) (PTBMA, amorphous), respectively, were used. The compatibility of both systems is described. In block copolymers of compatible components, Tc depends on the composition, but it is less than in comparable blends. Provided a sufficient crystallization time is available, Tm is, in effect, only dependent on the PEO molecular weight. In block copolymers of incompatible components both Tc and Tm were strongly determined by molecular weights of all blocks of both components and, connected with that, by PEO domain sizes. Tc vs. Tm diagrams are presented and discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1991.010420906
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    Paper (German National Licenses)
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