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Biomedical subjects

J Bojsen

Publications and source records attributed to J Bojsen.

At least 37 records · Page 2Linked to original sources
PubMed1980

Improvement of glucose homeostasis in insulin-dependent diabetics using a miniature insulin infusion pump with a fixed profile.

Glucose homeostasis was studied in nine longstanding insulin-dependent diabetic patients using a portable pump for intravenous insulin infusion. The 24 h infusion dose was calculated from the conventional SC insulin treatment. The range of basal infusion rates was 2.5 to 15 mU/min and peak delivery rates were raised up to 16-fold from start of main meals for 30-60 minutes. Mean blood glucose improved from 12.0 +/- 2.4 to 6.4 +/- 1.0 mmol/l (SD) during infusion (p less than 0.01). Glucose excretion decreased from 23 g/24 h (range 1-42) to 4 g/24 h (range 0-14) (p less than 0.01). Mean amplitude of glycaemic excursions was significantly improved during infusion (from 8.9 +/- 4.8 to 4.7 +/- 0.9 mmol/l; p less than 0.01). No severe hypoglycaemic episodes or other adverse reactions were seen.

Adult↗
PubMed1980

24-hour blood glucose profiles in insulin-dependent diabetics treated with intravenous insulin infusion systems. A comparison between closed- and open-loop systems.

The aim of this study was to compare the 24-hour blood glucose profiles of insulin-dependent diabetics during treatment with preprogramed insulin delivery systems with those of patients on treatment with the artificial beta cell (Biostator). Mean blood glucose (MGB) was 4.4 +/- 0.5 mmol/l for 15 controls, 5.8 +/- 1.0 for 53 patients on open-loop and 6.0 +/- 0.6 for 20 patients on closed-loop treatment. MBG was significantly higher in diabetics than in non-diabetic, but the difference between the two diabetic populations was not significant. Mean amplitude of blood glucose excursion was 1.8 +/- 0.6, 4.3 +/- 1.3 and 3.5 +/- 0.8 mmol/l respectively, the difference between the diabetic groups being significant. No hypoglycemia was seen in patients during closed-loop treatment, whereas this was the case in 10 of 53 patients on treatment with open-loop systems. Physical exercise resulted in small but normal decreases in blood glucose without hypoglycemia. Plasma insulin was within the normal range during both regimes. It is concluded that blood glucose control during treatment with closed-loop system is superior to that during treatment with open-loop systems. However, under standard conditions i.v. insulin infusion with preprogramed pump devices resulted in blood glucose fluctuations comparable with those during Biostator treatment.

Adolescent↗
PubMed1979

A portable, pre-programmable insulin infusion system in diabetes mellitus.

A miniaturized portable pump has been developed in order to study the effects of pre-programmed insulin infusion patterns on the blood glucose levels in juvenile-onset, insulin-requiring diabetics. Six diabetics undergoing 7 insulin infusion periods of up to 4 days were studied. The mean blood glucose was 7.0 +/- 2.3 (SD) mmol/l and the mean amplitude of glycemic excursions was 5.0 +/- 1.4 mmol/l. Success in achieving normoglycemia will depend on choosing the correct dose of insulin for infusion.

Adult↗
PubMed1979

Closed-loop system in evaluation of insulin infusion rates for an open-loop system.

The daily insulin requirements as calculated with a closed-loop system (Biostator), were used for insulin infusion with a portable, miniaturized pump in 6 juvenile-onset, insulin-requiring diabetics. Three diabetics were given insulin in a manner like that of the Biostator, e.g., maximal insulin infusion about 1 hour after start of meals. The MBG was 8.7 +/- 3.9 (SD) mmol/l. Three other diabetics had insulin in a fixed profile with peaks beginning simultaneously with meals. MBG of these patients was 4.4 +/- 1.9 mmol/l. Knowing the daily insulin dosage as calculated from the Biostator, normal blood glucose levels can be achieved with a fixed profile of insulin given by a portable pump.

Adult↗
PubMed1979

A portable, Preprogrammable insulin infusion system with 16 rates.

An external, portable, programmable pump has been developed for long-term therapeutic i.v. insusion of drugs. The impulse-controlled system consists of a 250 g CMOS-electronic unit and an electromechanical infusor (200 g) containing a 10 ml disposable syringe. The infusion pattern during the 24-h cycle is manually programmed in 16 steps from 24 to 384 microliter per 0.5 h. The coefficient of variation of the infusate is less than 2% per 0.5 h. An alarm circuit monitors the pump speed and the reservoir volume. The infusion system can operate continuously for 7 days with a 1 Ah, 5.4 volt battery.

Artificial Organs↗
PubMed1978

The glomerular filtration rate determined with 99mTc-DTPA and a portable cadmium telluride detector.

In twenty-two patients with 51Cr-EDTA renal clearance (glomerular filtration rate) values of 36-141 ml/min, the final plasma disappearance rate constant of i.v. injected 99mTc-DTPA (Sn) was found to be very close to that of 51Cr-EDTA determined from 180 to 300 min after injection. The disappearance of i.v. injected 99mTc-DTPA (Sn) was also recorded from the body surface by means of a low weight cadmium telluride detector (CRN, Strasbourg, France) and commercially available stationary or portable tape recorders. The disappearance rate constant of 99mTc-DTPA as determined externally from 30 min was comparable to that in plasma determined from 180-300 min. The external rate constant could be converted to plasma clearance by means of one plasma 99mTc-activity determination 180 min after injection. The calculated values agreed with the conventionally determined 51Cr-EDTA clearance values. The portability of the detector system allows it to be used to estimate alterations in GFR during the measurement due to changes in physical conditions such as posture, exercise, etc.

Equipment and Supplies↗
PubMed1978

A portable infusion pump, programmable with 16 rates.

An external, portable, programmable infusion pump has been developed for long-term therapeutic intravenous infusion of drugs. The impulse-controlled system consists of a 250 g CMOS-electronic unit, and an electromechanical infuser (250 g) containing a 10-ml disposable syringe. The infusion rate pattern is manually preprogrammed from 24 to 384 microliter/0.5 h. The coefficient of variation of the volume infused is less than 2% per. 0.5 h. The system has been tested by continuous administration of insulin in diabetics during 4 consecutive days, and can operate for 6-7 days with a 1 Ah, 5.4 V battery. The mean capillary blood glucose concentration could be maintained at levels close to normal (i.e. 7.0 mmol/1 +/- 2.3 (SD)) during the treatment period.

Adult↗
PubMed1977

Storage telemetry of radionuclide tracers by implantable thermoluminescent dosimeters.

A storage telemetrical method using thermoluminescent (TL) dosimeters for long-term measurements of incorporated radioactive substances in unrestrained rats has been developed. The system has been used in combination with radiotelemetrical registration of the circadian temperature rhythm. By sequential replacement of double TL dosimeters (60 mg, CaSO4:Dy) through an implanted silicon tube, the concentration of different radionuclides can be determined over long periods. The persistence of the circadian temperature rhythm indicates that the animals were unaffected by the experimental conditions. The relative uncertainty of the dosimeter system and the temperature transmitter is approximately +/- 2% (SD) at 5 mR exposures and +/- 0.05 degrees C, respectively. The weight of the system in total is 5.7 g. Disappearance studies (36-48 h) have been performed with the beta-emitters, 32P nad 42K, in subcutaneous tissues and tumor tissue. This TL method permits the repetition of an experiment on the same rat several times, and thereby avoids errors due to biological variations between animals.

Animals↗
PubMed1976

Circadian variations in 32P uptake of DMBA-induced mammary tumour and Walker carcinosarcoma in rats.

The 32P uptake in a mammary tumour induced by DMBA and in the Walker 256 carcinosarcoma was measured by external GM -tubes. The uptake was significantly higher than in the skin. During exposure to a synchronized light regime a circadian variation was present in the 32P uptake of the hormone-dependent DMBA-induced tumour. The maximal 32P uptake was in the dark period, in which the highest temperature in the tumour has also been found (Møoller and Bojsen, 1975). In the hormone-independent Walker 256 carcinosarcoma there was no periodicity in 32P uptake. No variation in 32P uptake was registered in the skin of normal controls or in tumour-bearing rats.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1976

Storage telemetric system for detection of radionuclide tracers in humans.

An external-storage telemetric device for continuous detection and registration of radionuclide tracers in humans is described. The weight of the system is 600 g. A pocket-sized ECG cassette tape recorder with 24-h continuous registration constitutes the storage unit. Two end-window GM detectors (Philips 18515) are used as surface detectors. Both gamma- and beta-emitters are detected by this equipment. The linear range is 100 counts/s. Renal excretion of [125I]iodide during 30 h in a normal person is shown. The disappearance rates are 0.1 h-1 during the day and 0.05 h-1 during the night. The coefficient of variation of the individual slopes has been calculated to less than 5%. A comparison with the analog radiotelemetric equipment is shown. The storage telemetric equipment can be applied outside the hospital, when the patient is ambulatory.

Electronics, Medical↗
PubMed1976

The diurnal variation in renal iodide excretion rate in rabbits.

The diurnal variation in renal iodide excretion rate was determined in unrestrained female rabbits by means of either a conventional clearance technique or a continuous monitoring of the whole body disappearance of iv injected 125I-iodide using an implanted Geiger-Muller detector. A distinct diurnal rhythm was detected in the disappearance rate of 125I-iodide. A slow disappearance rate occurred from 12 p.m. to 6 a.m. (darkness from 5 p.m. to 5 a.m.). The values of iodide excretion rate obtained by both methods were consistent like in humans with an excretion fraction of 0.3 for iodide in rabbits. In rabbits weighing 3-4 kg the renal iodide excretion rates were 5-7 ml/min during the rapid phase and 3-4 ml/min during the slow phase.

Animals↗
PubMed1976

The immediate effect of TSH on renal iodide excretion rate in rabbits.

The renal iodide excretion rate was determined in unrestrained female rabbits by means of conventional clearance technique or continuous monitoring of the whole body disappearance of iv injected 125I-iodide using an implanted Geiger-Muller detector. The immediate effect of pharmacological doses of bovine TSH was studied by both methods and a significant decrease in iodide excretion rate was recorded following the administration of a single TSH dose of 4 IU. The effect of TSH lasted 3-6 h. Injection of 10-20 mug TRH caused a transient delay in iodide disappearance (30-50 min) while 2-20 mug triiodothyronine iv or sc had no immediate effect on the iodide disappearance.

Animals↗
PubMed1975

Temperature and blood flow measurements in and around 7,12-dimethylbenz(a)anthracene-induced tumor and Walker 256 carcinosarcomas in rats.

By means of an implanted transmitter, a circadian rhythm of temperature was found both in 7,12-dimethylbenz(a)anthracene-induced tumors and in Walker 256 carcinosarcomas. There was no significant difference in the temperatures of the two tumors. The temperature was lowest in periods of rest, and the temperature difference between light and dark periods was about 1 degree. Both tumors were found to have a higher temperature than that of s.c. tissue. External temperature measurements of the skin covering the 7,12-dimethylbenz(a)anthracene-induced tumor by thermistor probe and by thermography showed a temperature 1-2 degrees below the temperature of surrounding skin areas. In the 7,12-dimethylbenz(a)anthracene-induced tumors the blood flow was low, which should correspond to a relatively small heat production, although the temperature was relatively high. Blood flow in skin overlying tumor was high, presumably a perifocal hyperemic reaction, although the temperature was relatively low in this area. Thus tissue temperatures was not indicative of blood flow.

9,10-Dimethyl-1,2-benzanthracene↗