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  • Hypothalamo-neurohypophysial system  (3)
  • islet amyloid  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Localisation of islet amyloid polypeptide and its carboxy terminal flanking peptide in islets of diabetic man and monkey (1991)
    Springer
    Diabetologia 34 (1991), S. 449-451 
    Details
    ISSN: 1432-0428
    Schlagwort(e): Islet amyloid polypeptide ; islet amyloid ; Type 2 (non-insulin-dependent) diabetes mellitus ; Beta cell ; pancreas
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Islet amyloid polypeptide is a normal constituent of islet Beta cells and is derived from a larger precursor by removal of flanking peptides at the carboxy (C) and amino (N) terminals. The role of these flanking peptides in the formation of amyloid in Type 2 (non-insulin-dependent) diabetes mellitus and in insulinomas is unknown. The C-terminal flanking peptide of islet amyloid polypeptide was localised by immunocytochemistry in human and monkey pancreatic islets from Type 2 diabetic and non-diabetic individuals by use of specific polyclonal antisera. Immunoreactivity for the C-terminal peptide was found in insulincontaining cells in both diabetic and non-diabetic tissue: no antibody binding was detected in islet amyloid of Type 2 diabetic man or of monkeys although a positive reaction occurred with antisera for islet amyloid polypeptide. The C-terminal peptide was localised by immunogold electron microscopy in the insulin granules in both diabetic and nondiabetic individuals but, unlike islet amyloid polypeptide, was not detected in lysosomes. The absence of immunoreactivity for the C-terminal peptide in amyloid suggests that incomplete cleavage of this flanking peptide from islet amyloid polypeptide is not a factor in the formation of islet amyloid.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00403186
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  • 2
    Digitale Medien
    Digitale Medien
    Chronic overproduction of islet amyloid polypeptide/amylin in transgenic mice: lysosomal localization of human islet amyloid polypeptide and lack of marked hyperglycaemia or hyperinsulinaemia (1993)
    Springer
    Diabetologia 36 (1993), S. 1258-1265 
    Details
    ISSN: 1432-0428
    Schlagwort(e): Islet amyloid polypeptide ; amylin ; transgenic mouse ; islet beta cell ; islet amyloid ; glucose metabolism ; insulin resistance ; Type 2 (non-insulin-dependent) diabetes mellitus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Type 2 (non-insulin-dependent) diabetes mellitus is characterised by hyperglycaemia, peripheral insulin resistance, impaired insulin secretion and pancreatic islet amyloid formation. The major constituent of islet amyloid is islet amyloid polypeptide (amylin). Islet amyloid polypeptide is synthesized by islet beta cells and co-secreted with insulin. The ability of islet amyloid polypeptide to form amyloid fibrils is related to its species-specific amino acid sequence. Islet amyloid associated with diabetes is only found in man, monkeys, cats and racoons. Pharmacological doses of islet amyloid polypeptide have been shown to inhibit insulin secretion as well as insulin action on peripheral tissues (insulin resistance). To examine the role of islet amyloid polypeptide in the pathogenesis of Type 2 diabetes, we have generated transgenic mice with the gene encoding either human islet amyloid polypeptide (which can form amyloid) or rat islet amyloid polypeptide, under control of an insulin promoter. Transgenic islet amyloid polypeptide mRNA was detected in the pancreas in all transgenic mice. Plasma islet amyloid polypeptide levels were significantly elevated (up to 15-fold) in three out of five transgenic lines, but elevated glucose levels, hyperinsulinaemia and obesity were not observed. This suggests that insulin resistance is not induced by chronic hypersecretion of islet amyloid polypeptide. Islet amyloid polypeptide immunoreactivity was localized to beta-cell secretory granules in all mice. Islet amyloid polypeptide immunoreactivity in beta-cell lysosomes was seen only in mice with the human islet amyloid polypeptide gene, as in human beta cells, and might represent an initial step in intracellular formation of amyloid fibrils. These transgenic mice provide a unique model with which to examine the physiological function of islet amyloid polypeptide and to study intracellular and extracellular handling of human islet amyloid polypeptide in pancreatic islets.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00400803
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  • 3
    Digitale Medien
    Digitale Medien
    Immunophenotypic evidence for distinct populations of microglia in the rat hypothalamo-neurohypophysial system (1995)
    Springer
    Cell & tissue research 280 (1995), S. 665-673 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Microglia ; Hypothalamo-neurohypophysial system ; Antigen-presenting cells ; Blood-brain barrier ; Phagocytosis ; Immunohistochemistry ; Rat (Long Evans)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The morphology, distribution and immunophenotype of microglia throughout the adult rat hypothalamo-neurohypophysial system was examined. Four macrophage-associated antibodies (OX-42, F4/80, ED1 and ED2) were used; the expression of major histocompatibility complex antigens was investigated by use of antibodies against OX-6, OX-17 (MHC class II) and OX-18 (MHC class I). Three distinct types of microglia were identified. The first was located in the magnocellular nuclei; these ‘radially branched’ (‘ramified’) microglia had round cell bodies and long branched processes, and were strongly immunoreactive only for OX-42. The second was located outside the blood-brain barrier in the median eminence, pituitary stalk and neurohypophysis often close to blood vessels; these ‘compact’ microglia had irregular cell bodies and shorter processes, and were strongly labelled by OX-42 and F4/80, weakly labelled by OX-18, and generally unlabelled by ED1, ED2, OX-6 and OX-17. The third type was found in small numbers throughout the system at the surface of the neurvous tissue or around blood vessels; these ‘perivascular’ microglia were elongated cells with no branching processes, and were strongly labelled by ED1, ED2, OX-18, OX-6, OX-17 and F4/80 antibodies but showed variable OX-42 immunoreactivity. Cells in a perivascular location were heterogeneous with respect to their immunophenotype. The presence in the normal adult rat hypothalamo-neurohypophysial system of MHC class-II molecules (OX-6 and OX-17) on a sub-set of perivascular microglia suggests that these cells are capable of presenting antigen to T lymphocytes. The microglia, which lie on either side of the blood-brain barrier, are well placed to facilitate interaction between the immune and neuroendocrine systems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318369
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  • 4
    Digitale Medien
    Digitale Medien
    Improved visualization of the immunoreactive hypothalamo-neurohypophysial system by use of immuno-gold techniques (1986)
    Springer
    Cell & tissue research 243 (1986), S. 193-204 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Hypothalamo-neurohypophysial system ; Supraoptic nucleus ; Neurosecretory granules ; Neurophysins ; Lysosomes ; Immuno-gold techniques ; Double-immunolabeling ; Monoclonal antibodies ; Murids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ultrastructural post-embedding immuno-gold techniques were applied to the supraoptic nucleus and the neurohypophysis of mice and rats. The primary antibodies were three different monoclonal antineurophysins, used in protein A-gold and immunoglobulin-gold procedures. Conventional plastic embedding as well as hydrophilic media (L.R. White) were used; non-osmicated and osmicated tissues were immunolabeled; sodium metaperiodate oxidation was used, but was not essential for immunolabeling. Vasopressinergic and oxytocinergic NSGs were identified by the specific immunoreactivity of their respective neurophysins on adjacent thin sections, and by sequential double labeling on the same thin section using two different antibodies associated with gold probes of different diameters. The immunoidentification indicates that vasopressin NSGs can additionally be differentiated as larger, with more electron-dense matrix, and susceptible to damage by sodium metaperiodate. The only organelles consistently labeled were neurosecretory granules (NSGs), either intact or within lysosomal configurations. Some lysosomal dense bodies were immunoreactive even when discrete NSGs were no longer morphologically recognisable within them. Labeled NSGs were located within neuronal cell bodies, along axonal shafts and within axonal swellings and endings; occasionally immunoreactive NSGs were observed within synaptic boutons. Labeling intensity was semi-quantitatively gauged by counting gold particles in relation to numbers of NSGs per axonal varicosity. The precise localisation achieved with particulate immunogold labeling surpasses that previously obtained with diffuse electron-dense immunoreaction products.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00221868
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  • 5
    Digitale Medien
    Digitale Medien
    Immunophenotypic evidence for distinct populations of microglia in the rat hypothalamo-neurohypophysial system (1995)
    Springer
    Cell & tissue research 280 (1995), S. 665-673 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Key words: Microglia ; Hypothalamo-neurohypophysial system ; Antigen-presenting cells ; Blood-brain barrier ; Phagocytosis ; Immunohistochemistry ; Rat (Long Evans)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The morphology, distribution and immunophenotype of microglia throughout the adult rat hypo- thalamo-neurohypophysial system was examined. Four macrophage-associated antibodies (OX-42, F4/80, ED1 and ED2) were used; the expression of major histocompatibility complex antigens was investigated by use of antibodies against OX-6, OX-17 (MHC class II) and OX-18 (MHC class I). Three distinct types of microglia were identified. The first was located in the magnocellular nuclei; these ’radially branched’ (’ramified’) microglia had round cell bodies and long branched processes, and were strongly immunoreactive only for OX-42. The second was located outside the blood-brain barrier in the median eminence, pituitary stalk and neurohypophysis often close to blood vessels; these ’compact’ microglia had irregular cell bodies and shorter processes, and were strongly labelled by OX-42 and F4/80, weakly labelled by OX-18, and generally unlabelled by ED1, ED2, OX-6 and OX-17. The third type was found in small numbers throughout the system at the surface of the nervous tissue or around blood vessels; these ’perivascular’ microglia were elongated cells with no branching processes, and were strongly labelled by ED1, ED2, OX-18, OX-6, OX-17 and F4/80 antibodies but showed variable OX-42 immunoreactivity. Cells in a perivascular location were heterogeneous with respect to their immunophenotype. The presence in the normal adult rat hypothalamo-neurohypophysial system of MHC class-II molecules (OX-6 and OX-17) on a sub-set of perivascular microglia suggests that these cells are capable of presenting antigen to T lymphocytes. The microglia, which lie on either side of the blood-brain barrier, are well placed to facilitate interaction between the immune and neuroendocrine systems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318369
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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