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Biomedical subjects

U Fischer

Publications and source records attributed to U Fischer.

At least 343 records · Page 19Linked to original sources
PubMed1978

Pancreatic and hepatic balances of endogenous insulin and of glucose in the anaesthetized dog during primed and non-primed infusions of glucose and of mannitol.

Simultaneous monitoring of pancreatic and hepatic blood flows and serial analyses of blood glucose and immunoreactive insulin activity in arterial, portal, intestinal and hepatic venous blood were performed in anaesthetized laparotomized dogs. Based on these measurements, the rates of pancreatic insulin secretion, of hepatic insulin uptake and the hepatic glucose balance were computed. Under basal conditions pancreatic output was about 40% of the total hepatic insulin input. 30% of hepatic insulin inflow were actually taken up in the liver. During a primed i.v. glucose infusion (steady blood glucose concentration about 330 mg/100 ml) pancreatic and hepatic blood flows increase rapidly and the insulin secretion exhibits a biphasic pattern. The relative part of hepatic insulin inflow taken up in the liver remained unchanged. A non-primed i.v. glucose infusion provoked a slow increase of blood flow and a rapid but monophasic increase of insulin release. Under these conditions the relative hepatic insulin uptake was transiently increased. During both loads hepatic glucose balance switched from release to uptake. However the non-primed infusion was more effective. When pancreatic and hepatic blood flows were increased without any blood glucose alteration by an infusion of mannitol, insulin secretion did not change; hepatic uptake of insulin decreased, but hepatic glucose output was clearly reduced. A correlation between the rates of insulin secretion, of hepatic insulin inflow and of insulin uptake was observed under all conditions. However, the hepatic glucose balance was correlated to the inflow of insulin or glucose and to the hepatic insulin uptake under certain conditions in individual experiments only.

Animals↗
PubMed1977

[Studies on blood traumatization following heart-valve prosthesis].

In 47 patients blood traumatisation was checked after interventions on cardiac valves. The cases in question were: 34 implantations of valve prostheses, 10 valve reconstructions and 3 re-operations because of paravalvular leakages. The tested valve prostheses according to Starr-Edwards, Björk-Shiley and Beall revealed subclinical haemolyses of various degrees. In aortic position the values for Björk-Shirley prostheses showed advantages as compared to the Starr-Edwards valve. Of all tested valve types the Beall prostheses caused the highest blood traumatisation. Manifest haemolytic anaemia was found only in 3 cases, two of them showing paravalvular leakage. In the cases of double valve replacement performed with combined Starr-Edwards and Beall prostheses the haemolysis was only slightly higher than in cases of mitral valve replacement with Beall valves only. In three cases with paravalvular leakage the parameters of haemolysis increased very much, returning to normal in 2 patients after successful correction. The assessment of the parameters of blood traumatisation is indispensible for the choice and improvement of the different types of valves and essential for the diagnosis of paravalvular leakage as well as for the control after leakage repair.

Anemia, Hemolytic↗
PubMed1977

The mechanism of insulin secretion after oral glucose administration V. Portal venous IRI concentration in dogs after ingestion of glucose.

Concentrations of immunoreactive insulin activity and of blood glucose were measured in portal and peripheral venous blood in six conscious dogs after oral administration of 1.0 g/kg glucose. Portal venous samples were obtained either by chronic catheterization or by direct puncture of the portal vein through a London-cannula. Portal venous IRI was already significantly increased 5 min after the onset of the stimulus. Peripheral venous IRI pattern reflected this early increase, but the peripheral venous blood glucose level was unchanged. The results indicate that the early peripheral venous IRI increase reflects a pancreatic insulin secretory reflex.

Administration, Oral↗
PubMed1977

[The effect of Suisynchron on the glucose tolerance and the plasma insulin in bitches].

Suisynchron, a derivative of bisthio-urea commonly used for oestric synchronisation, was applied to nine female Alsatians over 21 days. All animals received intravenous glucose injections before ten, and 21 days from the beginning of treatment as well as 21, and 84 days after the end of treatment. The glucose-stimulated plasma insulin levels were significantly reduced during Suisynchron treatment and 21 days after the end of treatment. Both glucose tolerance and response of free fatty acids remained unaffected. This phenomenon might be attributable to a stimulated hepatic insulin degradation, to a biguanid-like effect on "peripheral" glucose turnover, or to an inhibited secretion of hormonal insulin antagonists of the anterior lobe of the pituitary gland. However, the long persistence of the Suisynchron action after interruption of treatment, could not be explained by any of these effects.

Animals↗
PubMed1977

[Blood traumatization after heart valve replacement (author's transl)].

Blood traumatization after heart valve reconstruction or replacement was checked in 47 patients. Among the types of prostheses tested the Beall-valve caused the highest subclinical hemolysis, the Björk-Shiley-valve the lowest. In the aortic position the values for the Björk-valve were better than those for the Starr-valve. In cases with double valve replacement (Starr in aortic, Beall in mitral position) hemolysis was not much higher than in cases with single Beall mitral valve replacement. Clinical hemolytic anemia was only observed in 3 patients, 2 of them being affected with paravalvular leakage. In cases of paravalvular leakage parameters of hemolysis was very high and became normalized after successful repair in 2 patients.

Adult↗
PubMed1976

The effect of meal feeding and of sham-feeding on insulin secretion in dogs.

After feeding intact conscious dogs 1000 g mashed meat, peripheral venous immunoreactive insulin activity (IRI) increases before any enhancement of amino nitrogen concentration. This course of IRI is paralleled by a decrease of free fatty acids. Meal feeding in dogs, whose pancreatic juice is completely diverted from the gut by a fistula, is followed by a similar IRI increase without a distinct enhancement of amino nitrogen. In oesophagus fistula dogs, sham-feeding meat in 9 out of 15 experiments results in a considerable early IRI increase which is correlated with a small but a significant decrease of blood glucose and free fatty acid concentrations. In these tests there was no amino nitrogen alteration either.

Amino Acids↗
PubMed1976

Pancreatic blood flow in conscious dogs after oral administration of glucose.

Dogs with electromagnetic flowprobe implanted around the superior pancreaticoduodenal artery and with an hydraulic occluder implanted upstream from the flowprobe were examined between the 3rd and the 8th postoperative day. During an oral glucose load, blood flow increased from the beginning of administration to about 25 minutes, but not when blood glucose and plasma IRI exhibit their maxima. The rise of pancreatic blood flow is assumed to be produced by reflexes similar to those stimulating insulin secretion and exocrine pancreatic function during the early phase of an oral glucose load.

Administration, Oral↗
PubMed1976

[Evidence of pseudoisocyanine--positive endocrine cells in the gastric mucosa of the dog].

The tunica mucosa of the stomach and the other parts of the intestine (duodenum, jejunum, ileum colon) of the dog has been investigated in order t to demonstrate insulin producing cells. By means of thepseudoisocyanine-reaction it was possible to visualize in the lamina epithelialis of the stomach singular cells containing metachromatically reacting granules. It was possible to distinguish these cells from mast cells localised outside of the lamina epithelialis of the tunica mucosa. The value of this observation is given by the fact that until now hormone producing cells could be demonstrated in the laimina epithelialis of stomach and intestine of mammalia with exception of insulin-producing cells.

Animals↗
PubMed1976

[Influence of vagotomy on glucose tolerance and on the responses of plasma insulin and exocrine pancreatic function followed glucose load or food ingestion in dogs].

A part of the intrapancreatic nerve fibres of dogs show 1-2 months after bilateral truncal vagotomy a decay of the medullary sheath; in addition, the histochemically demonstrable insulin content of the B-cells is reduced. These animals do no longer react to oral glucose administration or feeding a meat meal with a reflectoric early rise of plasma insulin concentration and of exocrine functional parameters (all the animals were bearing exocrine pancreas fistulas). The glucose tolerance and and the decrease of free fatty acids in serum were restricted. Also, the content of bicarbonate and protein in the pancreatic juice and the insulin secretion of vagotomized animals are strongly reduced in the subsequent test phase (up to 120 min) following oral or i.v. glucose administration and after feeding meat. The inhibition of exocrine volume secretion following i.v. glucose administration was enhanced by the intervention. The findings confirm the involvement of the N. vagus in the mechanisms of the enteroinsular axis that becomes active together with exocrine gastro- and duodenopancreatic reflexes to any kind of physiological enteral stimulation.

Animal Feed↗
PubMed1976

The mechanism of insulin secretion after oral glucose administration. VII. Exocrine pancreatic function and plasma-IRI in dogs with chronic pancreatic fistulas.

During an intravenous glucose test, conscious dogs with exocrine pancreatic fistulas showed a reduction in the secretions of water, protein and of bicarbonate. This reduction is related to hyperglycemia and to IRI increase in the peripheral venous blood. After oral administration of glucose, however, a biphasic stimulation of the exocrine function was observed. During the first 15 minutes when insulin secretion increases independently of the blood glucose increase, all exocrine pancreatic functions are transiently stimulated, too. A second peak of the exocrine secretions is to be observed when glucose absorption and insulin secretion exhibit their maximum.

Administration, Oral↗
PubMed1976

[Studies on anesthetized and nonanesthetized slaughter swine. 1. Blood pressure].

The blood pressure of pigs for slaughter were measured. Onset of electric anaesthesia was followed by blood pressure rise of about 25 per cent. Peak values of 100 per cent in excess of the original pressure were recorded in some cases. Termination of the electric stimulus, generally, was followed by sudden blood pressure drop. The original pressure usually was reached ten seconds from the debleeding puncture. With continued debleeding, it stayed at 75 mm Hg after 50 seconds on average. Extraordinary high rise in blood pressure in response to electric stimulation usually was followed by rapid pressure drop, whereas in cases with moderate rise at the time of anaesthesia the subsequent decline was at slower rates.

Anesthesia↗
PubMed1976

The mechanism of insulin secretion after oral glucose administration. VIII. Pancreatic juice insulin excretion after glucose loading and meal ingestion in normal and vagotomized dogs.

On pancreatic fistula dogs, in the pancreatic juice, immunoreactive insulin has been identified. Insulin excretion is shown to be inhibited by an intravenous glucose load and to be stimulated in a biphasic manner by an oral glucose load or by ingestion of mashed meat. Insulin excretion is reduced 2 months after bilateral truncular vagotomy and the reaction to both oral stimuli is abolished. -- There is no statistical correlation between pancreatic juice insulin and blood glucose, plasma IRI, or plasma amino nitrogen concentrations. Single extrainsular B-cells shown by histologic examination are suggested to be the source of pancreatic juice insulin. Compared to insulin secreted into the portal blood flow, insulin in the pancreatic juice amounts to only 0.1--0.2% of the daily secretory rate of the islets of Langerhans.

Administration, Oral↗
PubMed1975

Dynamics of canine pancreatic blood flow and of insulin secretion during an intravenous glucose load.

Blood flow through the superior pancreaticoduodenal artery of anaesthetized dogs increases immediately after an i.v. glucose load and parallels to glycemia, but not to insulin output. Flow of superior mesenteric, and femoral arteries as well as of portal vein are also enhanced after rapid i.v. injections of glucose or mannitol. Extent and duration of all flow increases are dose-dependent and strongly related to the alterations of arterial plasma osmolality (maximum increase 24 mosmoles/kg). Heart rate, mean arterial blood pressure, and hematocrit remain unchanged after the first test minute. There is a considerable decrease of peripheral vascular resistance in the circulatory regions investigated. Flow through aorta ascendens is augmented for a short time. Possible mechanisms of vasodilatation are reflexes produced by osmoreceptors and/or local effects of osmolality on the tonus of vascular muscle. Within the physiological range pancreatic perfusion does not determine the amount of insulin released.

Animals↗
PubMed1975

Estimation of pancreatic IRI output rate and its relations to glucose tolerance in normal anasthetized dogs.

The pancreaticoduodenal and portal venous blood flows were recorded electromagnetically in anaesthetized dogs. Blood glucose and IRI were measured in the arterial, portal, and peripheral venous as well as in the intestinal venous blood. By a mathematical model the actual net IRI output of the whole pancreas was estimated. Under basal conditions it is 10.2 +/- 2.4 mU/min (n = 30; 26 kg mean body wt.). After i.v. glucose injection, IRI output is rapidly enhanced. The biphasic nature of this reaction was unequivocally demonstrated by consideration of the ratio IRI output : blood glucose. Pancreaticoduodenal blood flow increases transiently in relation to the increased blood glucose concentration. The IRI secretion rate is well correlated with the blood glucose concentration and to the amounts of glucose or of blood reaching the whole pancreas. It is also correlated with the portal IRI Concentration. The overall peripheral venous or arterial IRI concentrations are correlated with the IRI secretion rate, but not in all individual experiments. The different phases of IRI output (basal rate, stimulated output 1-10 min and 10-60 min) show no influence on each other, nor are they correlated with the peripheral IRI concentration area. Basal IRI output is negatively correlated with the glucose assimilation constants. These constants or the peripheral BG areas, however, are independent of the stimulated IRI output rate. However, both the assimilation constants and the peripheral BG areas are related to the peripheral IRI concentration areas. Hepatic uptake of insulin and dynamics of pancreatic blood flow seem to contribute considerably to the estimated correlation pattern.

Animals↗
PubMed1975

[The uptake of oxygen and glucose by the gingiva in diabetes mellitus with various forms of periodontal diseases].

Gingiva biopsy samples from healthy individuals and from diabetics with different forms of periodontal disease were incubated in the Warburg apparatus for 2 hours. Considerable reduction in oxygen consumption and glucose uptake was found in each type of periodontal disease, the most marked reduction being stated in case of parodontopathia dystrophica. The extent of the metabolic disturbance as well as the appearence of periodontal disease correlated with the duration of diabetes on the one hand with the frequency and severity of diabetic retinopathy on the other hand.

Adult↗
PubMed1975

[The mechanism of insulin secretion following oral glucose administration. 4. Inhibition of the early reflectoric phase of plasma insulin increase through atropine].

In the first phase after on oral glucose load or after sham-feeding of glucose in conscious intact or on the oesophagus fistulated dogs respectively, the peripheral venous plasma insulin concentration increases independently of any blood glucose alteration. After previous intravenous atropin injection, this reflectoric insulin secretion cannot be observed. The N. vagus is involved in the afferent and/or efferent side of the reinforcing mechanism of insulin secretion basing on the entero-insular axis. Additionally the enteral glucose absorption is inhibited.

Animals↗