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Biomedical subjects

U Fischer

Publications and source records attributed to U Fischer.

At least 289 records · Page 16Linked to original sources
PubMed1985

[Late results following femoral shaft fractures in childhood].

The results of 102 children with fractures of the femur shaft treated by osteosynthesis with dynamic compression plates (DCP) in comparison to 87 children which underwent a conservative treatment by extension are presented. Of 329 patients in a 15-years period, 238 children had a follow-up examination with evaluable data and 49 patients were excluded because of a different therapy such as plaster traction, cast, osteosynthesis with screws or nails etc. The children were divided into two groups: series I from 1968 to 1977 and series II from 1978 to 1982. 19.6% of the patients had a residual difference of more than 1 cm in the length of the legs. Operated children were twice as often afflicted as the conservative group. The amount of difference in the length depended on the duration of instability and increased when several repositions were required in the conservative group, or when an operation was carried out secondary to inadequate traction therapy. Axial deviation was found to be much more common in the extended group (16.1%) than in the operated group, in which only 4% axial deviations persisted in series II when DC-plates were used exclusively. Predominant in the conservative group was a persisting antecurvation in 13 of 14 children. Residual rotation malalignment of significant degree was found only in the group treated by extension, while the operated group averosed at minor torsion deformities. Children with closed epiphysis on the date of examination, who had a persisting rotation failure, had been treated nearly exclusively by extension (50% versus 15%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Daily glucose and insulin rhythms in diabetic dogs on the artificial beta cell.

The circadian periods of plasma glucose, insulin and alpha-amino nitrogen (alpha-AN) were studied in fed and fasting normal and diabetic dogs which were fed either beef or beef supplemented with carbohydrates (CH). The diabetics were either withdrawn from insulin supply or treated with an artificial beta cell (ABC) or infused a constant insulin dose (CI).--There was a significant daily glucose rhythm in normal fasting animals and in fasting diabetics on CI or on insulin withdrawal. In the fed controls, the phase of the rhythms depends on carbohydrate content of food. In CH-free fed controls the insulin maxima were related to alpha-AN but in CH-fed controls they were related to glycemia. Due to the mechanism of ABC-provided insulin dosage, the phases of glucose and of insulin oscillations were correlated in all diabetics on ABC. Thus even if the mean glucose level is normalized by ABC the intrinsic phase relations remain altered.--It is concluded that the daily glucose periodicity is based on endogenous rhythms in glucose production and utilization and is essentially independent of current insulin provision. But it is governed by the meals as main "Zeitgebers" and modified by the actual insulin supply.

Amines↗
PubMed1985

Measurement of plasma canine C-peptide by radioimmunoassay.

A sensitive radioimmunoassay (RIA) for canine C-peptide (CCP) was established using synthetic CCP, a specific antiserum, and rabbit anti-guinea pig serum. Radioiodination was performed according to a modified chloramine-T method. Tracer preparations were used for long as 6 weeks after iodination. The standard curve ranges from 0.028 to 3.0 nmol/l. The intra-assay coefficient of variation (CV) was 3-5% and the inter-assay CV was 6-9% in the optimal range between 0.3 and 0.8 nmol/l. The average recovery of CCP added to plasma samples was 100.6% (n = 9). Canine insulin, porcine proinsulin, bovine proinsulin, and human C-peptide exhibited no cross-reactivity. The mean fasting plasma CCP concentration was 0.089 +/- 0.021 nmol/l in normal dogs and -0.005 +/- 0.007 nmol/l (mean +/- SEM) in diabetic dogs, respectively.

Animals↗
PubMed1985

[Computed tomography and nuclear spin tomography in peripheral lymphedema].

The first reported findings on CT and N.M.R. in two cases of idiopathic peripheral lymphoedema are described. These methods have compared with the generally available volume estimations (volume estimation according to Kuhnke, immersion plethysmography) and have been considered in relation to visual and lymphographic examinations.

Adult↗
PubMed1985

In vivo comparison of different algorithms for the artificial beta-cell.

Using an extracorporeal artificial beta-cell in chronically diabetic dogs, the effects of four different mathematical models of glucose-controlled insulin dosage were compared: the Biostator algorithm (quadratic equation), Toronto algorithm (hyperbolic tangent function), Karlsburg algorithm (modified first-order derivative controller), and Ilmenau algorithm (second-order linear difference equation). The constants of all formulas implemented for the artificial beta-cell were obtained by regression analysis of paired blood glucose and plasma insulin data from normal control animals. Thus, they were biologically equivalent for all formulas. The patterns of blood glucose, insulin doses, and plasma insulin before, during, and after an intravenous glucose infusion test performed during the glucose-controlled insulin infusion showed no significant differences between the experimental groups subjected to the different algorithms. However, in no case were really normal blood glucose response curves restored by the artificial beta-cell. This might be due, first, to the fact that the algorithm parameters were not adapted to the actual individual insulin responsiveness, second, to the unphysiological peripheral venous route of insulin administration, and, third, to the lack of appropriate adaptation of the animals to normoglycemia.

Animals↗
PubMed1985

Canine C-peptide for characterization of experimental diabetes in dogs.

Radioimmunoassay of canine C-peptide (CCP) was developed for the characterization of endogenous beta cell function in experimentally diabetic dogs. The animals were rendered diabetic by subtotal pancreatectomy and intrasurgical infusion of 2 mg kg-1 streptozotocin into the superior pancreaticoduodenal artery. After an average duration of diabetes of 5 months the animals showed zero peripheral venous fasting CCP levels with no response to feeding, OGTT/i.v. glucagon loading or i.v. glucose tolerance testing. The data on CCP levels were entirely coincident with simultaneously measured plasma IRI levels. In non-diabetic control animals there were clear-cut CCP increases after all stimuli. The experimental model provided an IDDM-type diabetes without toxic symptoms but with sufficient exocrine pancreatic function. The comparison showed that plasma IRI analyses would also allow a reliable characterization of insulinogenic functions in these animals.

Animals↗
PubMed1985

[Vomiting].

Explore the source record for details and available documents.

Antiemetics↗
PubMed1984

[Homes for the aged and health resorts. Reflections on the quality of life in old age homes].

The quality of living in homes for the elderly and health resort institutions must be assessed in accordance with subjective and objective criteria. From the medical point of view, stress factors in the living area should be avoided, and health-promoting factors introduced. In this connection, consideration must be given to the biological, psychological and sociological aspects of ageing. Both in homes for the elderly and in health resort institutions, the particularly features of variability of interior design, compactness, clarity, safety, separation of functional rooms, furnishability and domestic comfort should be taken into account. The question of comfort (homeliness) in the health resort clinics, would appear to be an important factor, since it promotes patient contentment and willingness to cooperate, and thus also patient compliance.

Aged↗
PubMed1984

Long-term improvement in metabolic control of unstable type I diabetes by s.c. insulin injection patterns based on the dose profiles required by bed-side artificial beta-cell.

Twenty unselected unstable type I diabetic inpatients whose blood glucose control was insufficient employing three daily s.c. injections of regular insulin supplemented by intermediate acting insulin were subjected to a 48-hour treatment with the Biostator -GCIIS when both diet and muscular exercise were kept as close as possible to the conditions at home. The s.c. injection regimen was adjusted to the insulin dose pattern required by the artificial beta cell. There was significant metabolic improvement in 16 out of the 20 patients on discharge, in comparison to the pre-Biostator conditions. This improvement was still present when the patients were re-admitted after an average of seven months. It is concluded that in certain cases of unstable type I diabetes mellitus the metabolic re-arrangement based on intercalary days on an extracorporal artificial beta cell might be useful if the control constants are adapted to minimize the insulin requirement by the machine.

Adolescent↗
PubMed1984

Estimation of individually adapted control parameters for an artificial beta cell.

For optimum long-term glycemic regulation using a miniaturized artificial beta cell it is indispensible to estimate control parameters suited to the individual requirements of each diabetic patient. To solve this problem, a strategy has been developed which is based on engineering optimum-control theory with a model involving glucose and insulin interactions. The model considers physiologically relevant unit processes like endogenous glucose production, insulin-independent glucose uptake from its apparent distribution space, insulin-dependent glucose utilization, glucose-dependent insulin supply, and insulin catabolism. The assumed model structure is validated by results obtained in experimentally diabetic dogs using partition analysis. The individual parameter values of the model are obtained by a digital computer procedure based on a simple test which involves a bolus injection of glucose + insulin when a constant basal insulin dose is being administered in the diabetic in whom normoglycemia was re-established before the test. The method presented is recommended for future use in all cases where an optimized insulin regimen is to be worked out.

Animals↗
PubMed1984

Modelling the glucose-insulin system as a basis for the artificial beta cell.

The control constants for glucose-dependent insulin dosage in diabetic dogs were determined from test results in the opened system on the basis of a global blood glucose plasma-insulin control model. The controlled plant of the model consisted of the glucose and insulin subsystems; the entire insulin providing process was considered to be the controlling element, and the glucose-dependent insulin dose estimation, the controller. The constants obtained were employed in the extracorporeal artificial beta cell. The structure of the model and the numerical values of its state variables were verified by the prediction of blood glucose responses to intravenous glucose loads and by the correspondence between glucose balances and insulin doses as calculates and those as observed in diabetic animals. The application of the optimum control constant estimates in feedback-controlled insulin infusions provides improved blood glucose patterns but unchanged needs for insulin in comparison to the application of standard control parameters.

Animals↗
PubMed1984

Experience with an implantable glucose sensor as a prerequisite of an artificial beta cell.

A modification of a Clark-type glucose electrode which proved suitable for implantation and for connection to a glucose-controlled insulin infusion system is presented. It involves a third hydrophilic or perforated hydrophobic membrane and is based upon measurement of the H2O2 generated by the glucose oxidase reaction. The linear calibration range is greater than 40 mmol/l glucose concentration with a tau 95 of 360 or 600 s, respectively (different sandwich prototypes). There is reliable glucose-dependent sensor output up to a 15 mmol/l concentration when the pO2 is as low as 2 to 5 kPa as monitored in subcutaneous tissue. One prototype series of the sensor was employed for paracorporal (ex vivo) glucose monitoring in undiluted blood and for insulin infusions in diabetic dogs, which were feedback-controlled by the sensor's output. Another prototype was designed and applied for subcutaneous implantation. Tissue glucose concentration amounts to 30 to 50% of the simultaneously measured blood plasma glucose level which is mirrored in a total lag time (i.e. tau 95 of sensor and physiological delay in interstitial fluid) of 15-20 min. The glucose sensor presented provides a transient step towards a long-term functioning implantable instrument.

Animals↗
PubMed1984

Tracer kinetic studies of glucose and alanine metabolism in diabetic dogs on the artificial beta cell.

The in vivo glucose turnover was investigated employing [6-3H]glucose and [U-14C] glucose or [6-3H]glucose and [U-14C]alanine. Fasting chronically diabetic dogs at rest during short-term treatment with a bedside artificial beta cell were compared with normal animals in a glycemic steady state before, during, and after an i.v. load of unlabelled glucose. The insulin was infused into a peripheral vein. During the glucose-controlled insulin infusion glycemia was perfectly normalized, the concentrations of lactate and alanine remained elevated, pancreatic glucagon returned to normal, and the peripheral insulin levels were normal or slightly elevated in the diabetic dogs. Also the glucose turnover was in the normal range but the recirculation of the carbon label (i.e. the Cori cycle activity) was reduced. The alanine turnover and gluconeogenesis from alanine remained increased both in the basal state and during the glucose load. It is concluded that due to the absence of the physiological portosystemic insulin gradient, complete restoration of the physiological metabolic rates and control relations is not possible even if the blood glucose patterns are fully normalized.

Alanine↗