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  • artificial B cell  (3)
  • Insulin  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Automated feedback control of subcutaneous glucose concentration in diabetic dogs (1989)
    Springer
    Diabetologia 32 (1989), S. 573-576 
    Details
    ISSN: 1432-0428
    Keywords: Subcutaneous glucose ; enzyme electrode ; artificial B cell ; diabetic dog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The subcutaneous tissue is generally considered as a potential site for the monitoring of intracorporal glucose concentration by means of implanted sensors. We studied the suitability of using the resulting signal from the interstitial glucose concentration as an input in a feedback-controlled system for insulin administration. Miniaturized glucose electrodes (amperometric glucose oxidase sensors for the measurement of hydrogen peroxide) were implanted in insulin-dependent diabetic dogs. The output of these sensors was fed into the controller of a bedside-type artificial B cell. Insulin was infused by the device intravenously on the basis of a proportional-differential algorithm. The glucose patterns were compared to identical experiments where feedback control was accomplished on the basis of paracorporal blood glucose measurement using the same algorithm. Normoglycaemia was restored and maintained in both sets of experiments and oral glucose loads were well compensated for. It is concluded that the apparent subcutaneous glucose concentration is appropriate as an input signal for an artificial B cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00285330
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Glucose metabolism studied isotopically in diabetic dogs: Effect of restoration of peripheral normoinsulinaemia by the artificial B cell (1983)
    Springer
    Diabetologia 25 (1983), S. 411-417 
    Details
    ISSN: 1432-0428
    Keywords: Diabetic dog ; artificial B cell ; glucose metabolism ; tracer kinetics in vivo ; lactate ; carbon recirculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Normoglycaemia, peripheral normoinsulinaemia, and normoglucagonaemia were restored acutely in chronically diabetic dogs, using an extracorporal artificial B cell with peripheral venous insulin administration. Glucose metabolism was analysed by a non-steady-state tracer technique with double-labelled glucose (6-3H-and U-14C-glucose), and the incorporation of the 14C label into plasma lactate was determined. In the basal state, glucose turnover rates were not different from those in non-diabetic controls; but recirculation of the glucose-C label through the Cori cycle, and lactate labelling from glucose utilization were decreased. The glycaemic response to an intravenous infusion of non-labelled glucose was distinctly enhanced. This was based on a reduction in the rates of glucose disappearance. Its rates of appearance (total endogenous glucose production) were, however, suppressed to a normal extent by the exogenous glucose. Accordingly carbon recycling was nearly totally suppressed during the glucose infusion as in the controls. It is concluded that metabolic recompensation in these fasting, resting diabetic dogs remained incomplete because the interval of normoinsulinaemia, which obviously applied only to the peripheral circulation, was not long enough.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00282520
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A physiological solvent for crystalline insulin (1981)
    Springer
    Diabetologia 20 (1981), S. 51-53 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; crystal ; dissolution ; bicarbonate ; pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Insulin is insoluble in water at physiological pH, but dissolves relatively rapidly in plasma. To quantify the ability of various solutions to dissolve crystalline insulin, a simple assay measuring dissolution time was developed. At pH 7.5 and room temperature, distilled water, 0.154 mol/1 NaCl, Ringer's lactate solution, and 5% albumin in 0.154 mol/1 NaCl did not dissolve insulin crystals within 30 min. Normal postprandial human plasma and a proteinfree cell culture medium dissolved insulin crystals within 3 to 8 min. This ability was inhibited by acid titration of the fluids to a stable pH of 6.30, at which point bicarbonate depletion could be implied. Repletion of bicarbonate did restore the ability of these solutions to dissolve insulin crystals, but back-titration to the initial pH with NaOH did not. The effect of sodium bicarbonate alone was strongly concentration dependent above 23 mmol/1. We suggest that the ability of physiological fluids to dissolve insulin crystals at normal pH depends on their bicarbonate content. The ability to dissolve insulin with a physiological solvent which prevents its reaggregation promises to facilitate its use in portable pumping systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00253817
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A physiological solvent for crystalline insulin (1981)
    Springer
    Diabetologia 21 (1981), S. 51-53 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; crystal ; dissolution ; bicarbonate ; pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Insulin is insoluble in water at physiological pH, but dissolves relatively rapidly in plasma. To quantify the ability of various solutions to dissolve crystalline insulin, a simple assay measuring dissolution time was developed. At pH 7.5 and room temperature, distilled water, 0.154 mol/l NaCl, Ringer's lactate solution, and 5% albumin in 0.154 mol/l NaCl did not dissolve insulin crystals within 30 min. Normal postprandial human plasma and a protein-free cell culture medium dissolved insulin crystals within 3 to 8 min. This ability was inhibited by acid titration of the fluids to a stable pH of 6.30, at which point bicarbonate depletion could be implied. Repletion of bicarbonate did restore the ability of these solutions to dissolve insulin crystals, but back-titration to the initial pH with NaOH did not. The effect of sodium bicarbonate alone was strongly concentration dependent above 23 mmol/l. We suggest that the ability of physiological fluids to dissolve insulin crystals at normal pH depends on their bicarbonate content. The ability to dissolve insulin with a physiological solvent which prevents its raggregation promises to facilitate its use in portable pumping systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01789114
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    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The effect of prehepatic insulin administration on alanine flux rates in diabetic dogs (1987)
    Springer
    Diabetologia 30 (1987), S. 402-408 
    Details
    ISSN: 1432-0428
    Keywords: Alanine metabolism ; insulin-dependent diabetes ; dog ; isotopic study ; portal insulin infusion ; artificial B cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The in vivo flux rates of glucose (6-3H-glucose) and of alanine (U-14C-alanine) were measured in insulin-dependent chronically diabetic dogs which were infused with insulin employing a bedside-type artificial B cell and either the peripheral or the portal venous route. In comparison with non-diabetic control animals the diabetic dogs had near-normal patterns of glucose metabolism and pancreatic glucagon regardless of the route of insulin administration. They also showed reduced basal portal but moderately elevated peripheral insulin levels on peripheral and near-normal peripheral values on portal insulin infusion. Both concentration and production rates of alanine were reduced on peripheral (0.142±0.016mmol/l, 4.73±0.49 μmol·kg−1·min−1, p〈 0.05) but normal on portal insulin (0.206±0.030 mmol/l, 6.33±0.63 μmol·kg−1 ·min−1). The alanine clearance was slightly elevated or normal in the diabetic dogs, and the glucose production from alanine showed a strongly delayed response to an exogenous glucose load on either route of insulin administration. It is concluded that the peripheral hyperinsulinism during posthepatic insulin administration stimulates glucose utilisation to a normal extent, but inhibits the provision of amino groups in resting muscle. Alanine synthesis is thereby reduced, and the carbon moieties are shunted from glucose into circulating lactate. Long-term studies are needed to elucidate the role of the liver under these conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292542
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    Paper (German National Licenses)
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