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  • 1
    ISSN: 1432-0428
    Keywords: α-ketoisocaproate ; KIC ; arginine ; glucose ; glucagon release ; insulin release ; perfusion ; rat pancreas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects ofα-ketoisocaproate (KIC, 10 mmol/l) on glucagon and insulin release were studied in the in vitro perfused rat pancreas. The experiments were performed at low glucose concentration (3.3 mmol/l) in the absence or presence of arginine (10 mmol/l). In all the experiments KIC induced a marked and not rapidly reversible inhibition of glucagon release. This inhibition was more pronounced in the absence (76 percent) than presence of arginine (61 percent). These inhibitory patterns closely duplicated those which were seen in parallel experiments which included a rise in the concentration of glucose (from 3.3 to 11.1 mmol/l). KIC was also a potent stimulator of insulin release. The results are compatible with the view that the intracellular metabolism of KIC and glucose plays an essential role in the regulation of glucagon release by exogenous substrates.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 12 (1976), S. 531-538 
    ISSN: 1432-0428
    Keywords: Glucagon release ; insulin release ; pefused rat pancreas ; calcium ; glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The interrelationships between glucose and calcium in glucagon release were investigated using the dynamic system of the in vitro perfused rat pancreas. When calcium deprivation was induced in the presence of fixed concentrations of glucose prevailing throughout the experiments (3.3, 5.5, 8.3 and 16.6 mM), an enhancement of glucagon release invariably occurred, the shape and amplitude of such response differing in relation to the environmental glucose concentration. Such enhancement of glucagon release was readily reversible upon restoration of normal calcium levels. By contrast, during the period of calcium deprivation itself, glucagon release was little influenced by either raised (from 3.3 to 16.6 mM) or decreased (from 16.6 to 3.3 mM) glucose concentrations. These results clearly indicate that calcium plays, at least, a dual role — both inhibitory and permissivein glucagon secretion, but the intimate mechanisms by which calcium exerts such a dual action are at present unknown.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Glucose ; rat ; glucagon release ; insulin release ; perfused rat pancreas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of glucose upon the release of glucagon and insulin from the perfused rat pancreas in vitro was studied by varying both the concentration of glucose (from 3.3 to 4.6, 8.5, or 11.1 mmol/l) and the time of exposure to an elevated concentration of the sugar (5, 10 or 23 min). The results suggest that the amount of insulin released during the early period of stimulation could contribute to both the speed and extent of the inhibition in glucagon release. The rate of recovery from inhibition in the A cell, however, appeared to be independent of insulin and was related, in a dose-dependent and time-dependent manner, only to the glucose stimulus. It is suggested that a direct effect of glucose upon the A cell is involved in the physiological regulation of glucagon secretion. An indirect effect of glucose, as mediated via insulin release, may contribute to the rapidity and magnitude of inhibition in A cell secretory activity.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 10 (1974), S. 215-224 
    ISSN: 1432-0428
    Keywords: Glucagon release ; insulin release ; pancreatic pieces ; microtubular-microfilamentous system ; cytochalasin B ; colchicine ; vinblastine ; deuterium oxide ; arginine ; glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of a microfilament-modifier (cytochalasin B), of mitotic spindle-inhibitors (colchicine and vinblastine) and of a microtubule-stabilizer (D2O) on glucagon secretion were studied in vitro, using pieces of pancreas from duct-ligated rats. Cytochalasin B (10 μg/ ml) potentiated arginine-induced glucagon release, but was without effect on unstimulated glucagon release. Colchicine (10−4M) and vinblastine (10−4M) similarly stimulated arginine-induced glucacon release; colchicine did not affect unstimulated glucagon release. Deuterium oxide (100%, v/v) reversibly inhibited arginine-induced glucagon secretion. If it is assumed that the above mentioned drugs specifically interact with microfilaments and microtubules in the A2 cells, our results would suggest that a microtubular-microfilamentous system indeed participates in the process of glucagon secretion. The intimate mechanism by which such a system may apparently play both a restrictive and effector role in glucagon release remains, however, to be elucidated.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 11 (1975), S. 419-425 
    ISSN: 1432-0428
    Keywords: Combined radioimmunoassay glucagon ; insulin ; perfusion media ; human plasma ; computer program
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A combined radioimmunoassay for glucagon and insulin in biological fluids is presented. It is based on the use of 131I-glucagon and 125I-insulin tracers and a charcoal-dextran separation procedure. Standard curves, sample determinations and recovery studies gave comparable results whether in the combined or individual assay for glucagon and insulin. The combined assay, especially if supported by a decoding and calculating computer program, offers the advantages that it requires a smaller volume of the material to be sampled, is more economical and less timeconsuming.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Keywords: Radioimmunoassay of gluoagon ; glucagon secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Resume Une méthode de dosage radioimmunologique du glucagon comportant une séparation de l'antigène marqué libre et de l'antigène marqué lié à l'anticorps par du charbon-dextran est décrite. Les réactions d'équilibre glucagon-131I ou-125I (0.060 ng) et anticorps (antisérum de lapin 1∶550, dilution finale 1∶6600) atteignent leur équilibre en 3 jours à 4 °C. L'emploi d'un inhibiteur des protéinases (Trasylol) empêche la dégradation de la fraction immunoreactive du glucagon pendant l'incubation. La sensibilité de la méthode (〈 à 0.020 ng) correspond à environ 0.100 ng/ml de plasma. La précision, la reproductibilité, la spécificité du dosage et quelques problèmes liés à la séparation par le charbon-dextran sont étudiés. La récupération du glucagon ajouté à du plasma est d'environ 90%. La concentration en glucagon dans le plasma veineux périphérique est en moyenne de 0.208 ng/ml chez l'homme normal à jeun, de 0.396 ng/ml chez le chien anesthésié à jeun, de 0.354 ng/ml chez le rat nourri et de 0.909 ng/ml chez le canard à jeun. La méthode de dosage proposée semble actuellement limitée à l'étude de la sécrétion du glucagon in vitro car l'antisérum que nous utilisons présente une réaction croisée avec une substance d'origine duodénale. L'importance de l'interférence de cette substance dans l'estimation des concentrations en glucagon du plasma reste cependant à déterminer.
    Abstract: Zusammenfassung Eine radioimmunologisohe Bestimmungsmethode für Glucagon unter Zuhilfenahme von Dextran-Holzkohle für die Trennung des freien und des antikörpergebundenen markierten Antigens wird beschrieben. Das Gleichgewicht zwischen mit 125I und 131I markiertem Glucagon (0.060 ng) und Antikörper (Kaninchen-Antiserum 1∶550 in einer Endverdünnung von 1∶6600) wird bei 4 °C in 3 Tagen erreicht. Der Zusatz eines Proteinasen-Hemmers (Trasylol) verhindert den Abbau der immunreaktiven Fraktion des Glucagons während der Inkubation. Die Empfindlichkeit der Methode erreicht etwa 0.100 ng/ml Plasma. Die Genauigkeit, die Reproduzierbarkeit, die Spezifität und einige Probleme, die bei der Trennung durch Dextran-Holzkohle auftauchen, werden untersucht. Die Wiederauffindungsquote für dem Plasma zugesetztes Gluoagon betrug ca. 90%. Die mittlere Glucagon-Konzentration im peripheren venösen Plasma bei fastenden Normalpersonen lag bei 0.208 ng/ml, beim fastenden anaesthesierten Hund bei 0.396 ng/ml, bei 0.354 ng/ml für die gefütterte Ratte und bei 0.909 ng/ml bei fastenden Enten. Die vorgeschlagene Bestimmungsmethode scheint nur für Untersuchungen über die in vitro Sektretion von Glucagon brauchbar zu sein, da das von uns verwandte Antiserum eine Kreuzreaktion mit einer aus dem Duodenum stammenden Substanz zeigt. Wie stark dieser Stoff die Messung von Glucagon-Konzentrationen im Plasma stört, bleibt noch festzustellen.
    Notes: Summary A dextran-coated charcoal radioimmunoassay of glucagon is described. Antigen (131 or 125I-glucagon, 0.060 ng) — antibody (rabbit antiserum 1∶550, final dilution 1∶6600) reactions reached equilibrium within 3 days at 4 °C. The use of a proteinase inhibitor (Trasylol) prevented incubation damage of the immunoreactive glucagon. The sensitivity of the assay (〈 to 0.020 ng) corresponds to about 0.100 ng/ml of plasma. The precision, the reproducibility, the specificity of the assay and some problems related to the dextran-charcoal separation have been studied. Recovery of glucagon added to plasma was approximatively 90%. The mean gluoagon concentration measured in peripheral venous plasma was 0.208 ng/ml in normal human subjects after an overnight fast, 0.396 ng/ml in anaesthetized dogs after an overnight fast, 0.354 ng/ml in fed rats and 0.909 ng/ml in the overnightfasted duck. Up to now, the use of the assay seems to be restricted to studies of glucagon secretion in vitro since our antiserum cross-reacts with a material extracted from the duodenum. The relative contribution of this material in the plasma glucagon determinations remains, however, to be established.
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  • 7
    ISSN: 1432-0428
    Keywords: Insulin release ; anomeric specificity ; partial pancreatectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Attenuation, suppression or even inversion of the normal preference of glucose-stimulated insulin release for the α-anomer of the hexose was recently proposed to represent a feature of Beta-cell glucotoxicity in Type 2 (non-insulin-dependent) diabetes mellitus. Since recent reports emphasize the possible significance of Beta-cell secretory hyperactivity as a determinant of such a glucotoxicity, the anomeric specificity of glucose-induced insulin release was examined in normoglycaemic partially pancreatectomized rats. About 80–85% of the pancreas was removed, the animals then being given sucrose via their drinking water up to the time of killing. In these animals, α-D-glucose was more efficient than β-D-glucose in stimulating insulin release from the perfused pancreas, the α/β ratio in insulin output not being significantly different from that found in control rats. It is concluded, therefore, that the anomeric malaise, taken as a manifestation of Beta-cell glucotoxicity, it attributable to hyperglycaemia rather than to Beta-cell secretory hyperactivity.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé L'≪insulinémie apparente≫ a été estimée dans des serums de rats ou des mélanges d'insuline et d'adrénaline par les méthodes du diaphragme et du tissu adipeux de rat. Chez le rat, l'autogreffe ou l'énucléation de la surrénale augmentent l'≪insulinémie apparente≫, alors que l'adjonction d'adrénaline à un sérum normal la diminue. L'adrénaline, à concentrations physiologiques, n'agit pas en antagoniste, mais en inhibiteur de l'insuline. Enfin, l'augmentation de l'≪insulinémie apparente≫ consécutive à la dilution du sérum semble être due, à la fois, à la dilution des substances antagonistes et inhibitrices, en particulier de l'adrénaline, et à la libération d'une fraction insulinique normalement masquée dans le sérum entier.
    Abstract: Zusammenfassung Die insulinähnliche Aktivität von Rattenserum und Insulin-Adrenalin-Mischungen wurde mit der Zwerchfell- sowie mit der Fettgewebs-Methode gemessen und in μE/ml ausgedrückt. Demedullation oder Transplantation der Nebenniere bei der Ratte steigert die insulinähnliche Aktivität, die Zugabe von Adrenalin zum Normalserum dagegen vermindert sie. In physiologischen Konzentrationen wirkt Adrenalin nicht als Antagonist, sondern als Inhibitor des Insulins, da Adrenalin in Abwesenheit des Insulins ohne Effekt auf das Zwerchfell und auf das Fettgewebe ist. Die durch Verdünnen des Serums auftretende Steigerung der insulinähnlichen Aktivität scheint zwei Ursachen zu haben: Die Verdännung der hemmenden Substanzen (Adrenalin) und die Freisetzung einer im unverdünnten Serum unwirksamen Insulinfraktion.
    Notes: Summary The insulin-like activity (ILA) of rat serum and of insulin-adrenaline mixtures was estimated by both rat diaphragm and rat adipose tissue methods and expressed in μ units/ml. The ILA of the rat serum strikingly increases after demedullation or transplantation of the adrenal gland; the addition of adrenaline to normal rat serum decreases its ILA. In “in vitro” experiments, it was found that adrenaline exhibits an inhibitory but not antagonistic effect upon insulin activity, i.e. that adrenaline has no action upon muscle or adipose tissue in the absence of insulin. Finally the rise of the ILA provoked by dilution of rat serum seems to be due to the dilution of inhibitory substances (such as adrenaline) and to the liberation of an insulin fraction which is masked in the whole serum.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 45 (1967), S. 801-808 
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Hemodynamic studies were done in 36 patients with acute myocardial infarction during the first 24 hours. They were repeated in 19 patients on the following days. The following results were obtained: 1. During the first 24 hours cardiac output and stroke volume were more or less decreased, the peripheral vascular resistance increased compensatively. A marked peripheral vasoconstriction was also found in the patients with cardiogenic shock as a consequence of the decreased left ventricular output. 2. The remarkable finding on the second and third day was a normalisation of the peripheral vascular resistance or in some cases even a vasodilation. This regulation was not related to rise of temperature, which, for this reason, seems not to be of decisive importance. Only a sufficient increase in cardiac output will prevent arterial hypotension in these cases.
    Notes: Zusammenfassung Bei 36 Patienten mit akutem Myokardinfarkt wurden Kreislaufuntersuchungen innerhalb der ersten 24 Std nach Infarkteintritt durchgeführt, die bei 19 Patienten an den folgenden Tagen wiederholt wurden. Die Untersuchung führte zu folgenden Ergebnissen: 1. Innerhalb der ersten 24 Std nach Infarkt wurden ein mehr oder weniger erniedrigtes Herzzeit- und Schlagvolumen mit kompensatorisch erhöhtem peripheren Gefäßwiderstand gefunden. Eine ausgeprägte periphere Vasoconstriction als Folge der erheblichen Auswurfsminderung des linken Ventrikels war auch bei allen Patienten im kardiogenen Schock nachweisbar. 2. Am 2. und 3. Untersuchungstag ergab sich als auffälliger Befund bei der Mehrzahl der Patienten eine Normalisierung des peripheren Gefäßwiderstandes oder sogar in Einzelfällen eine periphere Vasodilatation. Dieses Verhalten wurde auch unabhängig von Temperaturerhöhungen beobachtet, so daß ihrem Einfluß allein nicht die entscheidende Bedeutung zugemessen werden darf. Nur eine ausreichende Steigerung des Herzzeitvolumens kann in diesen Fällen eine arterielle Hypotension verhindern.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 49 (1971), S. 1093-1096 
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die kardiale Wirkung einer intravenösen Injektion von 400 mg Aldadien-Kalium (Aldactone pro injectione) wurde bei 20 Patienten mit Angina pectoris oder chronischem Cor pulmonale untersucht. 10 Patienten waren digitalisiert, 7 unbehandelt und bei 3 Patienten wurde unter Aldosteroninfusion zunächst 1,5 mg Digoxin intravenös injiziert. Über den gesamten Untersuchungszeitraum von 90 min konnte ein signifikanter Anstieg des Herzzeitvolumens von 5,2±1,5 auf 6,0±1,5 l/min, des Schlagvolumens von 67±25 auf 80±28 ml,Δp/Δt des linken Ventrikels von 1 572±308 auf 1 861±160 mm Hg/sec,dp/dt des rechten Ventrikels von 484±132 auf 606±122 mm/sec und der systolischen Blutauswurfgeschwindigkeit von 265±56 auf 325±79 ml/sec nachgewiesen werden. Herzfrequenz, preload und afterload blieben unverändert. Damit ist der Beweis für eine signifikante positiv-inotrope Herzwirkung von Aldadien gegeben.
    Notes: Summary The cardiac effect of an intravenous injection of 400 mg Aldadienepotassium (Aldactone pro injectione) was investigated in 20 patients with coronary or pulmonary heart disease. 10 patients were digitalised, 7 were untreated and 3 patients at first got an Aldosterone-infusion, followed by an intravenous injection of 1.5 mg Digoxin. A significant raise of the following data was obtained over the entire course of the investigation (90 min): Cardiac output from 5.2±1.5 to 6.0±1.5 l/min; stroke volume from 65±25 to 80±28 ml;Δp/Δt of the left ventricle from 1 572±308 to 1 861±160 mm Hg/sec;dp/dt of the right ventricle from 484±132 to 606±122 mm Hg/sec; mean systolic ejection rate from 265±56 to 325±79 ml/sec. Heart rate, preload and afterload remained unchanged. Thus the significant inotropic effects of Aldadiene could be proved.
    Type of Medium: Electronic Resource
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