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To elucidate potential influences of the average tissue pO2 on the function of implanted glucose sensors, non-miniaturized polarographic oxygen electrodes and glucose oxidase/H2O2 glucose electrodes were implanted in the subcutaneous tissue of spontaneously breathing normal and diabetic dogs. There was no appreciable run-in phenomenon of oxygen sensors but(More)
A feasible and reliable method of in situ checking and calibration of implanted glucose sensors is required to compensate for alterations in the overall sensitivity of the "sensor plus subcutaneous fluid glucose compartment" system. In a study on nondiabetic dogs, the linear regression analysis of paired plasma glucose/sensor current data is validated as a(More)
Employing saline-impregnated cotton threads, an implanted-wick technique was adopted in dogs to obtain specimen from the subcutaneous interstitial compartment in order to estimate its glucose concentration. By measuring the protein, potassium and haemoglobin contents, the centrifuged wick fluid was shown to contain the interstitial concentration of solutes(More)
Amperometric glucose oxidase/hydrogen peroxide sensors were inserted subcutaneously into the neck of normal and diabetic dogs (n = 10), to elucidate the conditions for stable long-term functioning. Their output current was observed in parallel with measurements of plasma glucose concentrations and their function was checked by means of induced alterations(More)
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(More)
In IDDM, the gluconeogenic turnover of amino acids is increased even if glycemia is well controlled and may be restored to normal by means of prehepatic insulin substitution. Therefore, the present study was designed 1) to investigate the influence of route of insulin administration (portal versus peripheral) on the urea production rate, which is considered(More)
Glucose sensors often measure s.c. interstitial fluid (ISF) glucose rather than blood or plasma glucose. Putative differences between plasma and ISF glucose include a protracted delay during the recovery from hypoglycaemia and an increased gradient during hyperinsulinaemia. These have often been investigated using sensor systems that have delays due to(More)
This study was aimed at validating the in vitro estimated response characteristics of implanted glucose oxidase/H2O2 electrodes with respect to their in vivo function. Monoexponential non-linear regression analysis of sensor current vs. time curves in response to square alterations in glucose concentration gave response times T95 of between 1 and 5 min.(More)
The control of function of experimentally implanted glucose sensors needs an independent reference method. Employing saline-impregnated cotton threads, an implanted wick-technique was adopted in dogs to obtain analytical specimen from the subcutaneous interstitial fluid compartment. By measuring the contents of potassium, calcium, and hemoglobin, the(More)
The replacement of insulinogenic function in insulin-dependent diabetes has to restore the feedback between intracorporal glucose and insulin. This has been accomplished by the following approaches: (a) the so-called open-loop insulin treatment by means of injections or pumps, employing laboratory or other extracorporal analytical devices and closing the(More)