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  • Type 2 (non-insulin-dependent) diabetes mellitus  (3)
  • EMAT  (2)
  • 1
    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
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    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
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-0428
    Schlagwort(e): Type 2 (non-insulin-dependent) diabetes mellitus ; Macaca mulatta ; islet of Langerhans — pathology ; amyloid ; islet amyloid polypeptide ; beta cells ; obesity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Diabetes mellitus in Macaca mulatta rhesus monkeys is preceded by phases of obesity and hyperinsulinaemia and is similar to Type 2 (non-insulin-dependent) diabetes mellitus in man. To relate the progression of the disease to quantitative changes in islet morphology, post-mortem pancreatic tissue from 26 monkeys was examined. Four groups of animals were studied: group I — young, lean and normal (n=3); group II — older (〉10 years), lean and obese, normoglycaemic (n=9); group III — normoglycaemic and hyperinsulinaemic (n=6); group IV — diabetic (n=8). Areas of islet amyloid, beta cells and islets were measured on stained histological sections. Islet size was larger in animals from groups III (p〈0.01) and IV (p〈0.0001) compared to groups I and II. The mean beta-cell area per islet in Μm2 was increased in group III (p〈0.05) and reduced in group IV (p〈0.001) compared to groups I and II. Mean beta-cell area per islet correlated with fasting plasma insulin (r=0.76, p〈0.001) suggesting that hyper- and hypoinsulinaemia are related to the beta-cell population. Amyloid was absent in group I but small deposits were present in three of nine (group II) and in four of six (group III) animals, occupying between 0.03–45% of the islet space. Amyloid was present in eight of eight diabetic animals (group IV) occupying between 37–81% of the islet area. Every islet was affected in seven of eight diabetic monkeys. There was no correlation of degree of amyloidosis with age, body weight, body fat proportion or fasting insulin. Islet amyloid appears to precede the development of overt diabetes in Macaca mulatta and is likely to be a factor in the destruction of islet cells and onset of hyperglycaemia.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nondestructive evaluation 17 (1998), S. 141-152 
    ISSN: 1573-4862
    Schlagwort(e): Ultrasonic ; EMAT ; applied stress ; strain ; Rayleigh wave ; bridge
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik
    Notizen: Abstract The measurement of applied stress on bridges can provide valuable information on the condition of the structure. The conventional technique for measuring applied stress is with a strain gage. However, strain gages can be time consuming to install because first the surface must usually be prepared. On a bridge, paint removal will most likely be necessary as part of this surface preparation. When dealing with lead-based paints, which are considered hazardous waste, many time consuming removal procedures are required. Because of these factors, a device that measures applied stress without requiring paint removal could be useful. While a “clamp-on” strain gage can also be used to measure applied stress without requiring paint removal, this type of strain gage can not be used on some bridge details, such as webs of I-beams and tops of box girders. An ultrasonic technique using non-contact electromagnetic transducers provides a possible method for applied stress measurement which is not limited by the same factors as those with conventional strain gages. The transducers operate through nonconductive and conductive (lead-based) paint and work on rusted, pitted surfaces. Our previous research developed a technique for measuring applied stresses on bridges with EMATs and included many laboratory tests. This paper describes field applications of the technique on actual bridge structures, as well as additional system testing and instrument calibration in the laboratory.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nondestructive evaluation 17 (1998), S. 141-152 
    ISSN: 1573-4862
    Schlagwort(e): Ultrasonic ; EMAT ; applied stress ; strain ; Rayleigh wave ; bridge
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik
    Notizen: Abstract The measurement of applied stress on bridges can provide valuable information on the condition of the structure. The conventional technique for measuring applied stress is with a strain gage. However, strain gages can be time consuming to install because first the surface must usually be prepared. On a bridge, paint removal will most likely be necessary as part of this surface preparation. When dealing with lead-based paints, which are considered hazardous waste, many time consuming removal procedures are required. Because of these factors, a device that measures applied stress without requiring paint removal could be useful. While a “clamp-on” strain gage can also be used to measure applied stress without requiring paint removal, this type of strain gage can not be used on some bridge details, such as webs of I-beams and tops of box girders. An ultrasonic technique using non-contact electromagnetic transducers provides a possible method for applied stress measurement which is not limited by the same factors as those with conventional strain gages. The transducers operate through nonconductive and conductive (lead-based) paint and work on rusted, pitted surfaces. Our previous research developed a technique for measuring applied stresses on bridges with EMATs and included many laboratory tests. This paper describes field applications of the technique on actual bridge structures, as well as additional system testing and instrument calibration in the laboratory.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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