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Biomedical subjects

W Truppe

Publications and source records attributed to W Truppe.

18 recordsLinked to original sources
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

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↗
PubMed1979

Purification and properties of N-acetylgalactosamine 6-sulphate sulphatase from human placenta.

1. N-Acetylgalactosamine 6-sulphate sulphatase was purified about 20000-fold from the soluble extract of human placenta with N-acetylgalactosamine 6-sulphate-glucuronic acid-N-acetyl[1-(3)H]galactosaminitol 6-sulphate as substrate in the activity assay. The enzyme appears to be a glycoprotein with a mol.wt. of about 100000 as determined by gel filtration. On gel electrophoresis in the presence of sodium dodecyl sulphate the major protein band had a mol.wt. of 78000. Variable charge heterogeneity was observed in several enzyme preparations. 2. The purified enzyme released up to one sulphate molecule from the disulphated trisaccharide. It was active towards N-acetylgalactosamine 6-sulphate and exhibited no measurable N-acetylglucosamine 6-sulphate sulphatase or any other known lysosomal sulphatase activity. Hydrolysis of [1-(3)H]galactitol 6-sulphate was achieved by incubation neither with a crude nor with a purified enzyme preparation. Chondroitin 6-sulphate and keratan sulphate, as well as heparin and heparan sulphate, served as competitive inhibitors of the enzyme. 3. Purified N-acetylgalactosamine 6-sulphate sulphatase activity was optimal at pH4.9 and 4.4 when assayed in 0.02m-sodium acetate buffer and at pH4.2 and 5.2 in 0.1m-sodium acetate buffer. A single pH-optimum at pH4.8 was observed for the crude enzyme and for the purified enzyme after mild periodate treatment. The sulphatase activity was inhibited by a variety of anions and cations and activated by thiol-specific and thiol reagents.

Chondroitinases and Chondroitin Lyases↗
PubMed1978

[Studies on pinocytosis of proteoglycans and glycosaminoglycans (author's transl)].

Comparative studies were performed on the uptake of 35SO4-labelled proteoglycans and of free 35SO4-glycosaminoglycan chains by cultured skin fibroblasts. Proteoglycans as well as protein-free polysaccharide chains are internalized by adsorptive pinocytosis. The maximum capacity for endocytosis of proteoglycans is about four times higher than for glycosaminoglycan chains when referred to disaccharide units. On a molar basis about 10 times more glycosaminoglycan chains than proteoglycans can be internalized within a given time. Since unlabelled carbohydrate chains do not compete for the uptake of labelled proteoglycans it seems likely that different receptors exist on the cell surface for endocytosis of both types of macromolecules. 14C-labelled hyaluronate was neither pinocytosed to a measurable extent by skin fibroblasts nor by intima cells cultured from the thoracic aorta. Rat liver hepatocytes efficiently internalized hyaluronate by adsorptive pinocytosis. It was concluded from competitive experiments with hyaluronate oligosaccharides that hyaluronate has to interact with at least two receptor molecules on the cell membrane to achieve endocytosis.

Fibroblasts↗
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↗