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Biomedical subjects

W Mlekusch

Publications and source records attributed to W Mlekusch.

At least 37 records · Page 2Linked to original sources
PubMed1988

The effect of a saturated fat diet on pentobarbital induced sleeping time and phospholipid composition of mouse brain and liver.

Mice maintained for 48 d on a diet containing 10% partially hydrogenated coconut oil (PHCO) slept more than twice as long as mice maintained on a standard, laboratory mouse chow (CHOW) diet when injected i.p. with pentobarbital. At this time, the liver of mice maintained on the PHCO diet exhibited a decrease in the mol% of phosphatidylethanolamine and an increase in phosphatidylcholine and phosphatidylinositol compared to the liver of control animals. In the brain, no changes in phospholipid composition were detected. However, in both brain and liver, alterations in the fatty acid composition of the phospholipid classes were observed, with eicosatrienoic acid (20:3, n-9) increasing and the polyunsaturates, particularly docosahexaenoic acid (22:6, n-3), decreasing significantly. These changes in lipids of the brain and liver may be related to the prolonged sleeping time of the animals on the PHCO diet by altering the metabolism of pentobarbital in the liver and/or altering the sensitivity of the brain membranes to the presence of the drug.

Animals↗
PubMed1988

Quantitative characterization of diet effects on glucose tolerance in rabbits.

Normal, atherogenic and butter-enriched diets were given to three groups of rabbits during six months. The effects of the three forms of diet after six months were examined with the intravenous glucose tolerance test, which was evaluated by computer-aided model-fitting and parameter identification. Long-term effects are reflected in parameters such as pancreas sensitivity and the glucose utilization rate constant as a measure of peripheral insulin sensitivity. In these terms, the atherogenic diet caused a diminution of both pancreatic and peripheral sensitivity, whereas the butter-enriched diet led to an increase in glucose utilization and a decrease in pancreatic sensitivity relative to the system parameters of the normally fed control animals. Related to the findings about metabolic regulation are indications for an endocrinological approach to the problems of cholesterogenesis and atheroma formation.

Animals↗
PubMed1985

Effect of chronic alcohol consumption on rat brain microsome lipid composition, membrane fluidity and Na+-K+-ATPase activity.

The present study reports differences in phospholipid classes, fatty acids of individual phospholipids, and changes in membrane fluidity and Na+-K+-ATPase activity in brain microsomes of rats maintained on an alcohol diet for 35 days compared to sex, age and weight-matched control rats maintained on a calorically-equivalent, non-alcohol diet. Although no difference in Na+-K+-ATPase activity was found in microsomes from alcohol vs control rats when measured in the absence of added alcohol, the presence of low concentrations of ethanol (less than 100 mM) stimulated, while high concentrations (greater than 100 mM) inhibited enzyme activity. The stimulation was differentially expressed in that the microsomal enzyme from alcohol rats was stimulated to a lesser extent than the enzyme from control rats. However, the inhibiting effect of high concentrations of alcohol was similar in microsomes from both alcohol and control rats. Also in membranes from alcohol rats, there was a lower quantity of phosphatidylethanolamine (PE) and higher quantities of phosphatidylserine (PS) and phosphatidylinositol (PI) compared to membranes from control rats. The major change in fatty acid composition was a reduction in the level of polyunsaturated fatty acids, which was particularly evident in PI and PS. The linoleic acid: arachidonic acid ratio (18:2/20:4) and the saturation:unsaturation ratio were also increased in PI and PS in membranes from alcohol animals. However, the ratio of n-6/n-3 fatty acids remained the same or was reduced in membranes from alcoholic animals. Although no difference in the inherent "fluidity" of membranes from alcohol vs control rats could be demonstrated by electron paramagnetic resonance, molecular tolerance to ethanol was demonstrated in the membranes from alcohol rats by the resistance to the disordering effects of added ethanol.

Alcoholism↗
PubMed1981

Plasma concentrations of glucose, corticosterone, glucagon and insulin and liver content of metabolic substrates and enzymes during starvation and additional hypoxia in the rat.

The plasma levels of corticosterone, insulin and glucagon, and the concomitant changes in the levels of several liver enzymes and metabolites were measured in intact rats in the basal state during 24 hours and under conditions of food deprivation and hypoxia. The levels of the following enzymes and metabolites were examined: phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, pyruvate kinase, phosphofructokinase, glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, glucose, glucose-6-phosphate, glycogen, fructose-6-phosphate, hexokinase, tyrosine amino-transferase and tryptophan oxygenase. During food deprivation, the increased gluconeogenesis is possibly a result of glucagon activity. In contrast, however, during hypoxia the increase in gluconeogenesis seems to be a result of the higher plasma level of corticosterone. During starvation, the insulin concentration dropped steadily and came close to zero.

Animals↗
PubMed1980

The influence of an atherogenic, semisynthetic diet on cholesterol metabolism in rabbits.

The influence of a cholesterol-free, semisynthetic diet on the cholesterol content and on the incorporation of radioacetate into cholesterol in liver, aorta and intestinal mucosa of the rabbit was tested over periods of 3 and 6 months. The incorporation of radioacetate in the liver reached a maximum after 3 months. In contrast to this, the rate of acetate incorporation in the aorta and mucosa continued to rise throughout the entire test period. The cholesterol level in serum ran parallel to the hepatic cholesterol synthesis reaching a maximum after 3 months. While the cholesterol content of the liver remained unchanged, it rose in the aorta and mucosa. These results favour the assumption that hypercholesterolemia was not due to a defect in removal of cholesterol from the plasma compartment, but to an increased biosynthesis.

Animal Feed↗
PubMed1980

Studies of enzyme reactions in open systems.

An experimental arrangement is described which allows studies of the temporal performance of enzyme reactions (also reactions of complexes of enzyme chains) under conditions of open systems. The various steady-state properties of such open systems can be recognized by measuring their input and output [1,2]. The various levels of flowing equilibria are perturbed by applying molecular modulators to the system, and the data obtained are compared to those found in closed systems. In order to prove the accuracy of the experimental configuration, the determination of Km in a one-substrate reaction is carried out in the open system, using only one concentration of substrate at various flow rates.

Enzymes↗
PubMed1980

The influence of a cholesterol-free semisynthetic diet on the lipid metabolism in rabbits.

The influence of a cholesterol-free, semi synthetic diet on the total lipid synthesis and on the lipid content of serum, liver, aorta and intestinal mucosa of the rabbit was tested for the duration of three months, and, respectively, six months. Also, the changes in these parameters after a 38-hour period of fasting was examined. The total lipid synthesis in the liver and aorta ran parallel to the lipid level in serum with a peak in radioacetate incorporation into total lipids occuring after three months. In contrast to this the rate of lipid synthesis in the mucosa continued to rise throughout the entire test period. While the lipid content of the mucosa remained unchanged by the diet, it rose in the liver and aorta. The effect of fasting in the three organs was greater after three months than after six months in respect to the incorporation of radioacetate. The serum lipids, too, sank further during fasting after three months than after six.

Animals↗
PubMed1979

Multiple deficiency of mucopolysaccharide sulfatases in mucosulfatidosis.

Fibroblasts of four patients affected with mucosulfatidosis (multiple sulfatase deficiency, Austin variant of metachromatic leukodystrophy) were assayed for activities of the five sulfatases known to degrade mucopolysaccharides. These were iduronide 2-sulfate sulfatase, sulfamidase, N-acetyl-galactosamine 6-sulfate sulfatase, arylsulfatase B (N-acetylgalactosamine 4-sulfate sulfatase), and N-acetylglucosamine 6-sulfate sulfatase. The activities of these five sulfatases were severely depressed, thus confirming the known deficiency of arylsulfatase B and the absence of the Hunter and Sanfilippo III A corrective factors that have iduronide 2-sulfate sulfatase and sulfamidase activity, respectively. Together with earlier reports of the deficiencies of arylsulfatases A and C, cholesteryl sulfatase, and dehydroepiandrosterone sulfatae, mucosulfatidosis is now characterized by the deficiency of nine different sulfatases.

Acetylglucosamine↗
PubMed1976

Steatorrhea, a simple and rapid method of diagnosis.

A simple and rapid method for the diagnosis of steatorrhea is described. The method is based on the assessment of the difference of specific gravity and lipophilic property between a normal stool and that in steatorrhea, using a benzene-NaBr system. The stool samples are dried, pulverized, and then investigated. Steatorrhea is defined either as a fat or more in a 24-hour sample. Stool samples of 71 infants and children were examined. Among these were 23 healthy subjects, 10 with upper respiratory tract infections, and 6 with pneumonia. A further 31 children had celiac disease, 9 of them were on a gluten-free diet, and one child had cystic fibrosis. The procedure described renders single stool samples suitable for the assessment of steatorrhea. As a screening test the method proved to be rapid and accurate in the diagnosis of steatorrhea.

Adolescent↗
PubMed1976

Time function of corticosteroid levels in the blood plasma of rats under the influence of 222Rn inhalation.

The time function of cortocosteroid level in plasma of rats under two different 222Rn concentrations was investigated. Both curves show a maximum after 8h. Whereas the higher activity of 222Rn produces a second maximum after 5 days, the lower activity reaches its second maximum not before 9 days. From both time functions, a two-step mechanism in the intracellular control can be concluded.

Adrenal Cortex Hormones↗
PubMed1975

The effect of hunger on free fatty acid and corticosterone plasma levels in rats.

The time function of free fatty acids and of corticosterone in plasma in fed and fasted rats was investigated. Also a study of the influence of hypoxia on the concentration of plasma free fatty acids was carried out. Whereas fasting does not seem to stimulate lipolysis markedly before 12 h, 2 h of hypoxia elevate the free fatty acid level to its maximum. In the fasted condition, all values are significantly higher than corticosterone in the fed animal.

Animals↗