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  • 1
    ISSN: 1432-0428
    Keywords: Microdissected pancreatic islets ; ob/ob-mouse islets ; tissue culture ; insulin release ; insulin content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Microdissected pancreatic islets from non-inbredob/ob-mice, were cultured for 6 or 7 days in serum-free tissue culture medium 199. The insulin content of the islets decreased 60% during culture in 17 mM or 28 mM glucose and about 70% in the presence of 3.3 mM or 5.6 mM glucose. At the end of a culture period in high glucose, the sum of the insulin in the islet plus that in the culture medium was almost twice as high as the insulin content of fresh islets, indicating an active insulin biosynthesis. The maximal insulin response to glucose after culture in 17 mM or 28 mM glucose was about 40% of that in fresh islets; after culture in 3.3 mM glucose it was 10%. Half-maximal stimulation was observed at a glucose concentration of 5 mM for islets cultured with high glucose as compared to 9 mM for fresh islets. Like glucose, glibenclamide was a more effective insulin stimulator after culture with a high glucose concentration than with a low one. However, leucine-induced insulin release was not affected by the glucose concentration in the preceding culture medium. Whereas potentiation of glucose-stimulated release by arginine or dibutyryl-cAMP was independent of glucose concentration during the culture, theophylline released three times more insulin when the islets had been cultured with high glucose.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Pancreatic islets ; cold-storage ; culture ; glucose utilization ; oxygen consumption ; 86Rb+-uptake ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A previous study showed that the ability of glucose to stimulate insulin release was retained in islets stored at 8 °C for one week provided that glucose was present in a high concentration in the storage medium. The metabolic properties of islets stored in the cold have now been further explored in an attempt to clarify the protective effect of glucose. During storage in the cold the islet formation of 3H2O from (5-3H) glucose and oxygen consumption were only a few per cent of that of fresh islets whereas the uptake of 86Rb+ was 20–48%. Rewarming the cold-stored islets to 37 °C after one week of cold-storage restored the 86Rb+ uptake, the formation of 3H2O and 14CO2 from labelled glucose and oxygen consumption to 75, 80, 60 and 40% respectively of fresh islet levels. The results emphasize the usefulness of cold-storage for preservation of functionally intact isolated islets.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 7 (1971), S. 139-142 
    ISSN: 1432-0428
    Keywords: Pancreatic β-cell ; glycogen ; cyclic-3,5-AMP ; obese-hyperglycaemic mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Le glycogène a été mesuré dans des îlots pancréatiques isolés de souris obèses-hyperglycémiques. Les enregistrements ont été faits sur des extraits bruts de tissus, à l'aide d'un dosage enzymatique hautement spécifique. La quantité de glycogène dépendait de la concentration extracellulaire de glucose. Le 3′,5′-AMP cyclique dibutyril ainsi que des composés (glucagon et théophylline) connus pour augmenter le taux insulaire de 3′,5′-AMP cyclique, diminuaient le contenu en glycogène. L'adrénaline, dont l'effet inhibiteur sur la synthèse du 3′,5′-AMP cyclique a été rapporté, augmentait le taux de glycogène des îlots en présence de 3,0 mg/ml de glucose. Les résultats suggèrent que le taux de 3′,5′-AMP cyclique est un régulateur important du métabolisme du glycogène dans les cellulesβ insulino-sécrétrices.
    Abstract: Zusammenfassung An isolierten Pankreasinseln von fettsüchtigen, hyperglykämischen Mäusen wurde der Glykogengehalt gemessen. Die Untersuchungen wurden an rohen Gewebsextrakten mit Hilfe einer hoch spezifischen enzymatischen Methode durchgeführt. Der Glykogengehalt hing von der extrazellulären Glukosekonzentration ab. Dibutyryl-zyklisches 3,5-AMP als auch Substanzen (wie Glukagon und Theophyllin), welche bekannt sind, den zyklischen 3,5-AMP-Spiegel der Inseln zu heben, verminderten den Glykogengehalt. Epinephrin, das die Synthese von zyklischem AMP hemmen soll, erhöhte den Glykogenspiegel der Inseln in Anwesenheit von 3,0 mg/ml Glukose. Die Ergebnisse deuten darauf hin, daß der zyklische 3,5-AMP-Spiegel ein wichtiger Regulator des Glykogen-Metabolismus in der Insulin produzierenden Zelle ist.
    Notes: Summary Glycogen was measured in isolated pancreatic islets from obese-hyperglycaemic mice. The recordings were made on crude tissue extracts using a highly specific enzymatic assay. The amount of glycogen depended on the extracellular glucose concentration. Dibutyryl cyclic-3,5-AMP as well as compounds (glucagon and theophylline) known to increase the islet level of cyclic-3,5-AMP reduced the content of glycogen. Epinephrine, which has been reported to inhibit the synthesis of cyclic-3,5-AMP, increased the level of islet glycogen in the presence of 3.0 mg/ml of glucose. The results suggest that the level of cyclic-3,5-AMP is an important regulator of glycogen metabolism in the insulin-producingβ-cells.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 9 (1973), S. 403-412 
    ISSN: 1432-0428
    Keywords: Glucose metabolism ; islet adenosine-5-triphosphate ; insulin release ; intermediary metabolism ; microperifusion ; ob/ob-mice ; pancreaticβ-cells. starvation ; TCM 199 ; theophylline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Microperifusion was used to study the dynamics of insulin release and metabolic changes in pancreatic islets microdissected fromob/ob-mice. When the islets were suddenly exposed to a high glucose concentration, their content of glucose-6-phosphate and fructose-1, 6-diphosphate started to rise immediately, whereas a secretory response was not observed until after about 80 sec. This is consistent with the hypothesis that glucose metabolism initiates insulin release. Fasting the donor animals for 18 h reduced the initial phase of glucose-stimulated release but left the rise of glucose-6-phosphate, as well as the late phase of sustained release, unaffected. The use of a tissue culture medium (TCM 199) instead of Krebs-Ringer bicarbonate buffer as the basal medium increased the secretory responses to glucose, particularly the initial phase, both in islets from fed and fasted mice. However, the difference between fed and fasted mice remained. Theophylline did not restore the impaired initial secretory response after fasting. The responses of islet fructose-1,6-diphosphate and adenosine-5-triphosphate to glucose depended on the nutritional state of the animals and on the type of basal medium. No consistent correlation was observed between the changes of these substrates and the dynamics of insulin release.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Keywords: Anoxia ; glucose metabolism ; pancreatic islets ; Pasteur effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary When equilibrated with O2-CO2 (95:5), pancreatic islets of non-inbredob/ob-mice exhibited a sigmoidal dependence of3H2O production on D-(5-3H)-glucose concentration; the rate was most sensitive to changes of glucose concentration around 5mM and tended to be maximum above about 15 mM glucose.3H2O production from more than 5 mM D-(5-3H)-glucose was about twice as fast as the production of14CO2 from equimolar D-(U-14C)-glucose. Islets equilibrated with N2-CO2 (95:5) did not exhibit a sigmoidal dose-response curve for3H2O production, the process being inhibited by anoxia at glucose concentrations above 5mM. Pieces of exocrine pancreas had a slower aerobic3H2O production than the islets and showed a clear enhancement of the process during anoxia. In comparison with oxygenated islets, anoxic islets exhibited decreased concentrations of glucose-6-phosphate and increased concentrations of fructose-l,6-diphosphate. The concomitant inhibition of glycolytic flux may be due to a low lactate dehydrogenase activity in islets yielding a slow reoxidation of NADH and a slow phosphoglyceraldehyde oxidation under anaerobic conditions.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Archives of Biochemistry and Biophysics 162 (1974), S. 448-457 
    ISSN: 0003-9861
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Analytical Biochemistry 155 (1986), S. 177-181 
    ISSN: 0003-2697
    Keywords: ATP ; bioluminescence ; firefly luciferase ; glucokinase ; scintillation spectrometer ; serum glucose
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Analytical Biochemistry 50 (1972), S. 386-398 
    ISSN: 0003-2697
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/General Subjects 372 (1974), S. 127-134 
    ISSN: 0304-4165
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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