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K Kowalewski

Publications and source records attributed to K Kowalewski.

At least 19 recordsLinked to original sources
PubMed2000

Our own experience with CT angiography in early diagnosis of cerebral vascular malformations.

Computed tomography (CT) and intraarterial cerebral angiography are essential methods in early diagnosis of cerebral vascular malformations. In recent years however non-invasive or minimally invasive methods like MR angiography and CT angiography (CTA), which could potentially replace angiography, have been developed. The aim of presented study is to demonstrate our own experience in application of CTA in early diagnosis of cerebral vascular malformations. The material consists of 86 CTA examinations performed shortly after non-traumatic intracranial haemorrhage. Angiographic correlation has been available in 23 patients and surgical one--in 31 cases. CTA studies began with serio-CT to select the optimal time between contrast injection and CT scanning. After that 100-120 ml of non-ionic contrast medium was injected intravenously (5 ml per sec.) and spiral CT acqusition was performed with the delay calculated on the basis of the serio-CT. The obtained images were postprocessed on the workstation using always MIP and in many cases also SSD and VRT reconstructions. Vascular malformations have been diagnosed in 44 of 86 CTA studies including 38 patients with aneurysms (total number 51) and 6 patients with AVMs. In 17 cases the diameter of the aneurysm did not exceed 5 mm. In all surgical cases the CTA diagnosis of the aneurysm has been confirmed. There was however one false-negative case. On the other hand in 7 patients CTA revealed the small aneurysm, despite unclear angiographic appearance. In 2 of 6 patients with CTA suspicion of AVM this diagnosis has been excluded either by angiography or surgery. Comparison of CTA and angiography in 22 aneurysms showed in 17 cases superiority of CTA in evaluation of aneurysmal neck and the relationship between aneurysm and adjacent vessels (especially with VRT and SSD reconstructions). In patients with AVMs however the evaluation of supplying and draining vessels was better with angiography. On the base of our material we can conclude that CTA is very efficient in detecting and evaluating the aneurysms. We believe that CTA can replace angiography if it reveals aneurysm in a site corresponding with location of haemorrhage on CT. In patients with suspicion of AVM value of CTA is doubtful and angiography remains the method of choice.

Cerebral Angiography↗
PubMed1981

Transfer effects in feature-positive and feature-negative learning by adult humans.

In two experiments, college students performed a feature-positive or a feature-negative discrimination task based on colors or symbols and were then transferred to a feature-positive or feature-negative discrimination based on the other stimulus dimension (symbols-colors, colors-symbols). Initial task results yielded a substantial feature-positive effect and indicated that the color task was easier than the symbol task. Transfer task results indicated that the feature-positive effect was maintained and showed that consistent transfer (positive-positive, negative-negative) led to superior performance on the transfer task. These results were obtained when the correct solution to the initial task was provided to the subject prior to transfer (Experiment 1) and when it was not (Experiment 2). These results systematically replicated the existence of the feature-positive effect in adult humans and showed that both feature-positive and feature-negative discrimination learning were facilitated by consistent examples of these problems.

Discrimination Learning↗
PubMed1979

Some functions of canine liver perfused ex vivo with bloodless fluorocarbon emulsion.

6 canine livers were perfused extracorporeally with bloodless fluorocarbon emulsion for 6 h. Perfusate was oxygenated in vitro with a mixture of oxygen and carbon dioxide. Biochemical studies were performed on the samples of perfusate taken from the arterial and venous lines of the perfusion circuit, and of the bile. Hepatic tissue was sampled prior to and following 6 h of perfusion for histological and biochemical studies. Changes, if any, found in the concentrations of various components of perfusate and bile, were considered due to the metabolic activity of the liver. Moderate changes of the liver architecture and a decrease of glycogen were found in hepatic tissues studied microscopically. Under the conditions of the present preliminary experiment, canine livers remained functional after 6 h of perfusion.

Animals↗
PubMed1979

Composition of gastric mucinous secretion from Heidenhain pouches of dogs treated with aspirin.

Principal glycoproteins and amino acids of secretions from Heidenhain pouches were studied in control and aspirin-treated dogs in the resting state of fasting and during stimulation with pentagastrin. All samples showed the presence of galactose, galactosamine, glucosamine, glucose, fucose, mannose, uronic acid and sulfate. Galactose and glucosamine were found in equimolar amounts, and the galactose/galactosamine ratio was 2/1. Pentagastrin induced the reduction in concentration of major carbohydrate components and amino acids of gastric mucus. The concentrations of major carbohydrate components and of amino acids of gastric secretions were lower in aspirin-treated animals than in controls.

Amino Acids↗
PubMed1979

Secretion of insulin by the canine pancreas perfused ex vivo with fluorocarbon emulsion.

Canine gastroduodenopancreatic blocks were isolated and perfused ex vivo with oxygenated bloodless fluorocarbon emulsion. Pancreatic and gastric secretions were collected. Exocrine pancreatic secretion was stimulated with secretin infused intra-arterially. This study was undertaken to find out whether or not the pancreas, perfused with fluorocarbon emulsion, preserves its endocrine function. Immunoreactive insulin was determined in the perfusate samples obtained from a venous site in the perfusion circuit. Glucose concentration was also measured in the same samples. Insulin appeared in all experiments within the first ten minutes of persuion of the preparation with fluorocarbon. Insulin was present in all samples collected during 5.5 hours of perfusion. Results of this study suggest that endocrine function of the pancreas was preserved under the conditions of extracorporeal perfusion used.

Animals↗
PubMed1978

Effect of 16,16-dimethyl prostaglandin-E2 given intra-arterially or intra-gastrically, on acid secretion by canine stomachs perfused ex vivo.

Isolated whole canine stomachs, perfused ex vivo with homologous blood, were used for studying the effect of 16,16-dimethyl prostaglandin-E2 (dmPGE2) on gastric secretion. DmPGE2 was administered either into the gastric artery or instilled intragastrically through an esophageal cannula. Histamine, infused intra-arterially, induced acid secretion of all ex vivo stomachs and this was significantly inhibited by intra-arterially or intra-gastrically administered dmPGE2: volume of secretion, output of HCl and concentration of H+ were decreased and gastric peripheral vascular resistance was significantly reduced. The inhibitory action of dmPGE2 continued after its administration was stopped.

Animals↗
PubMed1978

Exocrine secretion of canine pancreas perfused extracorporeally.

A canine gastroduodenopancreatic block was isolated and perfused extracorporeally with homologous blood. This preparation was used for studying stimulated exocrine secretion of the pancreas. Stimulants were infused intra-arterially. Both vagi were stimulated electrically. Hydrochloric acid or L-phenylalanine were instilled intragastrically. Pancreatic secretion induced by secretin and during HCl instillation was rich in bicarbonate and poor in total protein. Pancreatic secretion obtained during the infusion of normal saline, cholecystokinin, bethanechol chloride or acetylcholine chloride and during instillation of amino acid as well as during electrical stimulation of vagi, contained less bicarbonate and more protein than secretin-induced secretion.

Acetylcholine↗
PubMed1978

Effect of ex vivo perfusion of isolated canine stomach with fluorocarbon on the composition of gastric tissues.

Isolated canine stomachs were perfused for 6 h with fluorocarbon emulsion suspended in a simulated physiological solution of electrolytes with glucose added. Gastric mucosa and extramucosal tissues of perfused stomachs were sampled for biochemical analysis of high energy phosphates, glucose and electrolytes. Comparable samples were also taken from normal canine stomachs, dissected under similar surgical conditions as the stomachs used for perfusion. Gastric tissue ATP, ADP and AMP were reduced but CP was increased in the tissues perfused with fluorocarbon as compared with controls. Gastric tissue water content and sodium were increased but potassium was reduced in a stomach so perfused. The biochemical tests performed were considered as viability tests of organs preserved-perfused in fluorocarbon prior to possible transplantation. Significance of the changes observed is discussed in the light of the current knowledge on energy metabolism.

Adenosine Diphosphate↗
PubMed1978

Effect of actinomycin D on pentagastrin- and histamine-stimulated secretion from isolated canine stomachs.

Pentagastrin- and histamine-stimulated secretion of HCl was investigated using isolated canine stomachs perfused ex vivo with homologous blood. The effect of actinomycin D, an inhibitor of DNA-dependent RNA synthesis, on the secretion of HCl by so stimulated stomachs was assessed. The purpose of this experiment was to find whether the trophic action of pentagastrin (RNA synthesis) is interdependent with the secretory action of this hormone. Such interdependence was found in rats by other investigators who reported the suppression of pentagastrin-induced HCl secretion and of RNA synthesis by actinomycin D. Our study did not demonstrate any effect of actinomycin D on pentagastrin-stimulated HCl secretion by isolated canine stomachs. It appears that in dogs the trophic effect of pentagastrin is independent from its secretory action. Review of the literature suggests that the mechanism of gastrin-like hormones on gastric acid secretion in dogs differs from the one found in rats.

Animals↗
PubMed1978

Myoelectrical and mechanical activity of isolated canine stomach perfused in vitro with fluorocarbon. Role of glucose, phosphate, calcium and strontium in the perfusate.

Myoelectrical and mechanical activities were recorded from whole isolated canine stomachs perfused, intravascularly, with fluorocarbon emulsion, oxygenated in vitro. The perfusate was composed of an oxygen carrier, fluorcarbon, emulsified with a surfactant added to a simulated physiological solution. Bipolar electrodes and a strain gauge were used for recordings. Stomachs perfused as above for 5 h displayed normal electrical and mechanical activities. 'Normal' meaning identical with those observed under in vivo conditions or during perfusion with homologous blood. Normal response to electrical stimulation of a vagus nerve branch or to intraarterial injection of methacholine or pentagastrin were also observed. These functions of smooth muscles were not altered when glucose-free or glucose-and phosphate-free perfusate were used. In calcium-free perfusate, electrical and mechanical activities were absent and no responses to stimulants used were recorded. When calcium was added to the perfusate, these functions were restored to normal. Strontium was found to be an adequate substitute for calcium in fluorocarbon perfusate. Gastric secretions were alkaline and contained fluorocarbon emulsion.

Animals↗
PubMed1978

Effect of somatostatin on pentagastrin stimulated secretion by isolated canine stomachs, perfused ex vivo with homologous blood.

The effect of somatostatin on pentagastrin-induced gastric secretion was assessed on 6 isolated canine stomachs perfused ex vivo with homologous blood. Hormones were given at a constant rate into the gastric arterial circulation. Somatostatin caused inhibition of the HCl concentration and output and reduced the secretion volume in all stomachs studied. The output but not the concentration of pepsin was also reduced.

Animals↗
PubMed1978

The effect of L-amino acids given intravenously on gastric secretion stimulated by pentagastrin in dogs.

L-Amino acid solution given intravenously in Heidenhain pouch dogs resulted in marked changes of both basal and pentagastrin-stimulated gastric secretions. During a 1-hour amino acid infusion, a significant augmentation of pentagastrin-induced secretion was observed. A significant increase of secretion during amino acid infusion was also found in dogs not infused with pentagastrin. Absolute values of HCl output were much higher in dogs in which secretion was stimulated by a combination of pentagastrin and amino acids than by amino acids alone. This increase was followed by a fall of gastric secretion in response to pentagastrin.

Amino Acids↗
PubMed1978

Secretory function of isolated canine pancreas perfused with fluorocarbon emulsion.

A canine gastroduodenopancreatic block was isolated and perfused ex vivo with fluorocarbon emulsion, oxygenated in vitro, and containing a simulated physiologic protein-free solution. Pancreatic and gastric secretions were collected. The pancreas was stimulated with secretin or cholecystokinin infused intra-arterially. The response of the pancreas to both hormones was essentially identical to that observed under in vivo conditions or during perfusion of the isolated pancreas with homologous blood. Secretin induced pancreatic secretion was rich in bicarbonate and poor in total protein. Cholecystokinin induced pancreatic secretion contained less bicarbonate and more protein than secretin induced secretion. Differences between secretory responses of the pancreas to these hormones were significant. Gastric secretion was alkaline and contained fluorocarbon emulsion. The results of this study demonstrated that, under the experimental conditions described, external secretory function of the isolated canine pancreas was preserved during perfusion of isolated organs with fluorocarbon emulsion.

Animals↗
PubMed1977

Myoelectrical and mechanical activity of stomach and intestine in hypothyroid dogs.

Myoelectrical activity was studied in normothyroid and hypothyroid Labrador dogs in the resting state, following injection of pentagastrin, bethanechol chloride, and after feeding. Hypothyroidism was produced by total thyroidectomy and chronic treatment with thiouracil. Electrodes were surgically implanted over the serosa of the stomach, duodenum, jejunum, and ileum and used for repeated recording of myoelectrical activity of gastrointestinal muscles. A strain gauge was implanted over the gastric antrum and served to record mechanical activity of the stomach. As compared with control dogs, hypothyroid animals showed (a) decreased frequency of electrical control activity of the stomach and jejunum, (b) decreased occurrence of electrical response activity (spike potentials) following stimulation, and (c) decreased mechanical response to the same stimulants, ie, pentagastrin, bethanechol chloride, and food.

Animals↗
PubMed1977

Effect of intra-arterial infusion of glucose on secretory activity of isolated canine stomach.

Totally isolated stomachs, perfused extracorporeally with homologous blood of living oxygenator dogs, were used for the study of gastric secretion. Pentagastrin or histamine were infused into the gastric artery alone or combined with a 30% solution of glucose. Hyperglycemia was associated with significant inhibition of gastric secretion. Volume, output of HCl and concentration of H+ in gastric secretion were decreased. Hyperglycemia induced also a significant increase in osmotic pressure of gastric secretion and gastric blood. Paired values of H+ and osmotic pressure of gastric secretion were analyzed by the method of least squares, using a computer. The regression line was given by the equation: osmotic pressure (mosm/kg)=311.2-0.167 X [H+] mEq/liter.

Animals↗