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  • 1
    ISSN: 1432-0428
    Keywords: Chinese hamster ; Cricetulus griseus ; endocrine pancreas ; islet of Langerhans ; A-cells ; B-cells ; D-cells ; spontaneous diabetes ; nuclear pores ; plasma membrane ; membrane-associated particles ; glycogen ; ultrastructure ; electron microscopy ; freeze-etching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The nuclear and plasma membranes of islet cells from non-glycosuric and diabetic Chinese hamsters were examined by freeze-etching. The B-cells of diabetic animals presented a slight increase in the number of nuclear pores and marked alterations in the number, size and distribution of membrane-associated particles in the plasma membrane. In A-cells, identified by the presence of characteristic bundles of coarse filaments in the perinuclear region, a definite increase in the number of nuclear pores was found in the most severely diabetic animals. These preliminary findings point to alterations in the membrane systems as possible determinants for the abnormalities of islet function in diabetes mellitus.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Diabetes ; EMC-virus ; islet cells ; immunofluorescence ; morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The endocrine cell populations of pancreatic islets in encephalomyocarditis (EMC)-virus infected mice were assessed quantitatively by immunofluorescence using specific antisera against 4 islet hormones. A marked reduction of the volume of insulin-containing (B-) cells (up to one tenth of control values) was observed at all stages studied in the hyperglycaemic mice. This was accompanied by the inversion of the normal ratio between B- and non B-cells. The volume of the latter cell types was also modified at different time points after infection: glucagon-cells were augmented 14 days after infection; PP-cells were decreased 2–3 days and 21 days after infection; somatostatin-cells decreased to one-fourth of control values in hyperglycaemic animals 21 days after infection. The latter results suggest that non B-cells are also involved in islet reaction to virus infection.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Pancreas ; islets of Langerhans ; insulin ; glucagon ; somatostatin ; pancreatic polypeptide ; immunohistochemistry ; embryology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Systematic sampling of human necropsy pancreases has revealed that pancreatic polypeptide (PP) cells are not distributed equally in the gland. PP-cells are the most abundant cell type in the posterior part of the pancreatic head while they are scarce or absent in the remainder of the gland. The PP-rich part of the head can be separated by blunt dissection from the pancreas as a discrete lobe. This lobe probably originates from the ventral pancreatic bud during embryogenesis. A quantitative study of the immunofluorescent endocrine cell types (insulin, glucagon, somatostatin and pancreatic polypeptide cells) in PP-rich and PP-poor regions of pancreases in 8 subjects with ages ranging from 33 fetal weeks to 80 years, showed that the proportions of the cell types were different in youngs and adults.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Keywords: l-methyl-l-nitrosourea ; streptozotocin ; insulin secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present experiments were designed to compare the effects of streptozotocin and l-methyl-l-nitrosourea upon glucose-induced insulin secretion by isolated islets of Langerhans. Both drugs depressed the insulin response at one and two hours incubation but higher molar concentrations of the nitrosourea were required to produce the same level of inhibition as streptozotocin, a difference perhaps related to the latter's glucose moiety.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0428
    Keywords: B-cell microtubules ; spontaneous diabetes ; spiny mice (Acomys cahirinus) ; DBM mice ; isolated islets ; vincristine-induced crystals ; electron microscopy ; morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The pancreatic B-cell contains microtubules, which are thought to participate in the process of insulin release. In order to disclose a possible abnormality of this B-cell microtubular system in animals with islet dysfunction, isolated islets from normal rats and mice, as well as from diabetic mutant mice (DBM mice) and from spiny mice (Acomys cahirinus) were incubated in the presence of vincristine, which causes the precipitation of the microtubular protein into paracrystalline deposits. Ultrastructural examination of the islets indicated that the volume-density of vincristine-induced deposits was markedly reduced in B-cells of spiny mice, when compared to that found in normal rats and mice and DBM mice. Exposure of the islets from spiny mice to a high glucose concentration, concomittantly to vincristine, caused a further reduction in vincristine-induced crystals content of the B-cell. It is speculated that an impairment of the B-cell microtubular system may account for the deficiency of insulin release found in spiny mice.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Keywords: Immuno-fluorescence ; gastro-intestinal tract ; somatostatin ; gastrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Evidence is presented that somatostatin-containing cells are present in the gastro-intestinal tract of the dog. Thus immuno-fluorescent cells were detected by the use of antiserum to cyclic somatostatin. These cells were mainly encountered in the antral mucosa and in the neighbourhood of gastrin-producing cells. No cross reaction was observed between gastrin and somatostatin. It is suggested that locally produced somatostatin controls gastrin secretion, and, more generally, that somatostatin-containing cells, multifocally distributed, modulates secretion of a large number of glands.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 23 (1982), S. 1-5 
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Conclusion The present report emphasizes the view that the acceleration of glycolysis occurring in islets stimulated by a rise in the extracellular concentration of glucose involves increases in both the availability of glycolytic intermediates, such as glucose-6-P and fructose-6-P, and the activity of the key glycolytic enzyme phosphofructokinase. We initially thought that such a dual mechanism could help to reconcile the substrate-site and regulatory-site hypotheses for the process of glucose-induced insulin release [33]. However, our more recent study on the properties of fructose-6-P,2-kinase now suggests that the increase in the rate of fructose-2,6-P2 synthesis may be mainly due to an elevation in the fructose-6-P content of the islet cells, an elevation itself attributable to a mass action phenomenon. We were also unable to detect any direct effect of glucose on the activity of phosphoglucomutase, the enzyme catalyzing the synthesis of glucose-1,6P2, another activator of phosphofructokinase. Therefore, there is as yet no convincing evidence that the molecule of glucose, whether located in the extracellular or intracellular fluid, interacts with a specific receptor to induce activation of a hypothetical glucosensor system. Obviously, the latter statement is not meant to deny that glucose binds to the stereospecific carrier mediating glucose transport across the B cell plasma membrane and to those enzymes (hexokinase, glucokinase, aldose reductase) catalyzing the first steps of its intracellular metabolism. Such binding phenomena, however, cannot be equated with the situation in which the insulin secretory response depends solely on the allosteric activation of an enzyme by a given secretagogue, as appears to be the case in islets stimulated by the nonmetabolized analogue of L-leucine, 2-aminobicyclo [2,2,12] heptane-2-carboxylic acid [34,35].
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 39 (1983), S. 1045-1046 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The amylase content of the acinar tissue is higher in the splenic region of the rat pancreas containing glucagon-rich islets than in the duodenal region harboring pancreatic polypeptide-rich islets.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 40 (1984), S. 1068-1075 
    ISSN: 1420-9071
    Keywords: Pancreas ; cyclic AMP ; role of ; insulin release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0428
    Keywords: Intestine ; insulin-releasing factor ; GLI ; islets ; pancreas pieces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Des extraits à l'acide éthanol ont été préparés à partir du coeur, duodénum, ileum + jejunum (TOT) du porc et TOT fractionnée sur colonne chromato-graphique. Avec les ilôts du rat et les morceaux de pancréas du rat, incubés dans du glucose 16.6 mM, on a déterminé pour chaque produit son activité insulinolibératrice (IRA). Les extraits de coeur et duodénum n'accrurent pas la libération d'insuline; le glucagon pancréatique et TOT l'augmentèrent significativement. La secrétine synthétique n'agit point sur la libération d'insuline, par les ilôts isolés, mais la pancréozymine très faiblement. La production d'insuline, par les ilôts et les morceaux, fut stimulée par quelques fractions de TOT, les effets dépendant des concentrations des fractions entre 5 et 250 μg/ml. Les contenus en GLI, pancréozymine et secrétine de ces produits furent comparés avec leurs IRAs. L'IRA, rapporté ici, n'est pas du à la secrétine, ni probablement à la pancréozymine. Il n'existe pas de relations quantitatives entre le GLI et IRA des fractions.
    Abstract: Zusammenfassung Säureäthanolextrakte wurden aus dem Ileum + Jejunum (TOT), Herz und Duodenum des Schweins zubereitet. TOT wurde mittels Säulenchromatographie fraktioniert. Die insulinfreisetzende Aktivität (IRA) dieser Stoffe wurde an Ratteninseln und Rattenpankreasstückchen bestimmt, die mit 16.6 mM Glucose inkubiert worden waren. Die Herz- und Duodenumextrakte hatten keine Wirkung auf die Insulinausschüttung. Pankreasglucagon und TOT bewirkten eine signifikante Erhöhung der Insulinfreigabe. Synthetisches Sekretin bewirkte keine Erhöhung der Insulinfreisetzung aus isolierten Inseln. Pancreozymin hatte nur eine geringe Wirkung auf die Insulinproduktion der Inseln. Einige der Fraktionen von TOT erhöhten die Insulinproduktion der Inseln und der Pankreasstückchen. Im Konzentrations-bereich von 5 – 250 μg/ml waren die Wirkungen dieser Fraktionen konzentrationsabhängig. Der GLI-, Pancreozymin- und Sekretingehalt dieser Stoffe wird mit ihren IRAs verglichen. Die hier beschriebene IRA wird nicht durch Sekretin verursacht, wahrscheinlich auch nicht durch Pancreozymin. Es besteht keine quantitative Wechselbeziehung zwischen der GLI und der IRA der Fraktionen.
    Notes: Summary Acid-ethanol extracts were prepared from pork ileum + jejunum (TOT), heart and duodenum. TOT was fractionated by column chromatography. The insulin-releasing activities (IRA) of these materials were determined using rat islets and pieces of rat pancreas incubated with 16.6 mM glucose. The heart and duodenum extracts were without effect on insulin release. Pancreatic flucagon and TOT significantly increased insulin release. Synthetic secretin did not increase insulin release by isolated islets. Pancreozymin had only slight effects on the insulin output by islets. Some of the fractions of TOT increased the insulin output of islets and pancreas pices. The effects of these fractions were concentration-dependent in the range 5 to 250 μ/ml. The contents of GLI, pancreozymin and secretin in these materials are compared with their IRAs. The IRA described here is not caused by secretin, and is probably not caused by pancreozymin. There is no quantitative correlation between the GLI and the IRA of the fractions.
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