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  • 1
    Electronic Resource
    Electronic Resource
    Indirect two-site immunoradiometric assay of rat and mouse proinsulin (1979)
    Springer
    Diabetologia 17 (1979), S. 235-242 
    Details
    ISSN: 1432-0428
    Keywords: Indirect two-site immunoradiometric assay ; rat proinsulin ; mouse proinsulin ; islets ; proinsulin/insulin ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An indirect two-site immunoradiometric assay for rat and mouse proinsulin using a rabbit antibody to synthetic rat C-peptide has been developed. The sensitivity of the assay is 0.006 pmol/ml. Proinsulin was 4.95% of the total proinsulin and insulin in extracts of rat pancreas and 5.45% in extracts of isolated rat islets. The mean fasting rat insulin and proinsulin concentrations were 0.13±0.09 pmol/ml (n=5) and 0.008±0.002 pmol/ml (n=5) respectively. The mean fasting mouse proinsulin concentration was 0.019±0.006 pmol/ml (n=8). In rats intravenous glucose produced a biphasic insulin response but proinsulin rose progressively to 0.021±0.011 pmol/ml at 45 min. In mouse oral glucose increased the proinsulin concentration to 0.13 pmol/ ml at 30 min. Proinsulin release from isolated rat islets was studied during intermittent or continuous high glucose (20 mmol/l) stimulation in static incubation. Significant increases in proinsulin release were only observed 90 min after initial exposure to high glucose whether glucose stimulation was continuous or intermittent. Both in vivo and in vitro glucose stimulation led initially to a fall in the proinsulin/ insulin molar ratio but later upon prolonged stimulation this progessively increased to above the basal value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01235860
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Hypertriglyceridaemia in subjects with normal and abnormal glucose tolerance: relative contributions of insulin secretion, insulin resistance and suppression of plasma non-esterified fatty acids (1994)
    Springer
    Diabetologia 37 (1994), S. 889-896 
    Details
    ISSN: 1432-0428
    Keywords: Non-insulin-dependent diabetes mellitus ; impaired glucose tolerance ; hypertriglyceridaemia ; hyperinsulinaemia ; non-esterified fatty acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Although plasma insulin and triglyceride concentrations are positively correlated in many studies, the relationships between insulin resistance, insulin secretion and hypertriglyceridaemia remain unclear. To study these associations, subjects between the ages of 40 and 64 were randomly selected from a general practice register and invited to attend for a standard oral glucose tolerance test for measurement of insulin, triglyceride and non-esterified fatty acid concentrations. The study comprised 1122 subjects who were not previously known to have diabetes and who completed the test. Using the World Health Organisation criteria, 51 subjects were classified to have non-insulin-dependent diabetes mellitus, 188 had impaired glucose tolerance and 883 subjects had normal glucose tolerance. Triglyceride concentrations in subjects with glucose intolerance were elevated compared to those in control subjects, even after adjustment for age, obesity and gender (p〈0.001 for subjects with diabetes and p〈0.01 for those with impaired glucose tolerance compared to normal subjects). In separate multiple regression analyses for males and females, the most important determinants of the plasma triglyceride concentration were the area under the non-esterified fatty acid suppression curve (p〈0.001 in both genders) and the waist-hip ratio (p〈0.001 for men and 〈0.01 for women). The fasting insulin concentration was independently associated with triglyceride concentration in women only (p〈0.01). The most important determinant of the area under the non-esterified fatty acid suppression curve in men was the 30-min insulin increment, a measure of insulin secretion, (p〈0.001) whereas for women age (p〈0.001) and the body mass index (p〈0.01) were the most important.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400944
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Intracellular localization and molecular heterogeneity of the sulphonylurea receptor in insulin-secreting cells (1995)
    Springer
    Diabetologia 38 (1995), S. 277-282 
    Details
    ISSN: 1432-0428
    Keywords: Key words Non-insulin-dependent diabetes mellitus ; insulin ; sulphonylurea receptors ; islets ; glibenclamide ; secretory granule.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sulphonylureas stimulate insulin secretion by binding to a receptor in the pancreatic beta-cell plasma membrane resulting in inhibition of ATP-sensitive K+ channels, membrane depolarization and thus influx of Ca2+ through voltage-dependent Ca2+ channels. Sulphonylureas can also induce hormone release at fixed membrane potentials without Ca2+ entry suggesting that these drugs may have other modes of action. We have determined whether different forms of sulphonylurea-binding proteins are present in insulin-secreting cells and their subcellular localization by density gradient centrifugation. Binding studies using [3H]-glibenclamide showed that islet and insulinoma membranes contained a single high affinity sulphonylurea binding site (Kd = 1 nmol/l). Photo-crosslinking of the drug to the membranes resulted in labelling of two proteins with apparent molecular weights of 170 and 140 kDa. The same analyses of insulinoma subcellular fractions showed that the majority ( 〉 90 %) of binding proteins were localized to intracellular membranes with only minor levels ( 〈 10 %) on plasma membranes. The 170 kDa sulphonylurea binding protein was present in both plasma and granule membrane fractions whereas the 140 kDa form was not present in the plasma membrane fraction. The differences in the molecular forms and subcellular distribution of the receptor are consistent with sulphonylureas having multiple sites of action in the pancreatic beta cell. [Diabetologia (1995) 38: 277–282]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400631
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Intracellular localization and molecular heterogeneity of the sulphonylurea receptor in insulin-secreting cells (1995)
    Springer
    Diabetologia 38 (1995), S. 277-282 
    Details
    ISSN: 1432-0428
    Keywords: Non-insulin-dependent diabetes mellitus ; insulin ; sulphonylurea receptors ; islets ; glibenclamide ; secretory granule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sulphonylureas stimulate insulin secretion by binding to a receptor in the pancreatic beta-cell plasma membrane resulting in inhibition of ATP-sensitive K+ channels, membrane depolarization and thus influx of Ca2+ through voltage-dependent Ca2+ channels. Sulphonylureas can also induce hormone release at fixed membrane potentials without Ca2+ entry suggesting that these drugs may have other modes of action. We have determined whether different forms of sulphonylurea-binding proteins are present in insulin-secreting cells and their subcellular localization by density gradient centrifugation. Binding studies using [3H]-glibenclamide showed that islet and insulinoma membranes contained a single high affinity sulphonylurea binding site (Kd = 1 nmol/l). Photo-crosslinking of the drug to the membranes resulted in labelling of two proteins with apparent molecular weights of 170 and 140 kDa. The same analyses of insulinoma subcellular fractions showed that the majority (〉90%) of binding proteins were localized to intracellular membranes with only minor levels (〈10%) on plasma membranes. The 170 kDa sulphonylurea binding protein was present in both plasma and granule membrane fractions whereas the 140 kDa form was not present in the plasma membrane fraction. The differences in the molecular forms and subcellular distribution of the receptor are consistent with sulphonylureas having multiple sites of action in the pancreatic beta cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400631
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Hypertriglyceridaemia in subjects with normal and abnormal glucose tolerance: relative contributions of insulin secretion, insulin resistance and suppression of plasma non-esterified fatty acids (1994)
    Springer
    Diabetologia 37 (1994), S. 889-896 
    Details
    ISSN: 1432-0428
    Keywords: Key words Non-insulin-dependent diabetes mellitus ; impaired glucose tolerance ; hypertriglyceridaemia ; hyperinsulinaemia ; non-esterified fatty acid.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Although plasma insulin and triglyceride concentrations are positively correlated in many studies, the relationships between insulin resistance, insulin secretion and hypertriglyceridaemia remain unclear. To study these associations, subjects between the ages of 40 and 64 were randomly selected from a general practice register and invited to attend for a standard oral glucose tolerance test for measurement of insulin, triglyceride and non-esterified fatty acid concentrations. The study comprised 1122 subjects who were not previously known to have diabetes and who completed the test. Using the World Health Organisation criteria, 51 subjects were classified to have non-insulin-dependent diabetes mellitus, 188 had impaired glucose tolerance and 883 subjects had normal glucose tolerance. Triglyceride concentrations in subjects with glucose intolerance were elevated compared to those in control subjects, even after adjustment for age, obesity and gender (p 〈 0.001 for subjects with diabetes and p 〈 0.01 for those with impaired glucose tolerance compared to normal subjects). In separate multiple regression analyses for males and females, the most important determinants of the plasma triglyceride concentration were the area under the non-esterified fatty acid suppression curve (p 〈 0.001 in both genders) and the waist-hip ratio (p 〈 0.001 for men and 〈 0.01 for women). The fasting insulin concentration was independently associated with triglyceride concentration in women only (p 〈 0.01). The most important determinant of the area under the non-esterified fatty acid suppression curve in men was the 30-min insulin increment, a measure of insulin secretion, (p 〈 0.001) whereas for women age (p 〈 0.001) and the body mass index (p 〈 0.01) were the most important. [Diabetologia (1994) 37: 889–896]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400944
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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