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Biomedical subjects

V Richter

Publications and source records attributed to V Richter.

At least 55 records · Page 3Linked to original sources
PubMed1988

[Lipoprotein metabolism in patients with disordered thyroid gland function before and following therapy].

Clinical manifest hypothyreosis leads to changes of plasma lipoproteins, which are characterized by elevated LDL levels, an increase of the relation LDL cholesterol/HDL cholesterol, an elevation of the quotient cholesterol/triglycerides within the VLDL and an increase of the relation HDL2/HDL3. Both these changes and the diminished activities of post-heparin lipase of hepatic and extrahepatic origin are reversible after substitution therapy. On the contrary, patients with hyperthyreosis M. Basedow show low lipoprotein levels, high activities of post-heparin lipase and an elevation of the relation of the apolipoproteins apo C II/apo C III within the VLDL fraction.

Adult↗
PubMed1988

The influence of dietary low and high unsaturated fats and cholesterol on the fatty acid pattern of serum and aortic cholesteryl esters and the lipid deposits of pig aorta.

16 three-month-old female pigs were divided into 3 groups. 6 animals received a semi-synthetic diet containing 15% sunflower oil (g/100 g food) and 1.25% cholesterol (SF group). In 6 animals the sunflower oil was replaced by beef tallow (BT group). 4 control animals 1.5% sunflower oil and without cholesterol. The serum cholesterol levels of the SF group rose moderately, those of the BT group moderately or highly. The relative lipid infiltrated intima area (LIA) and the cholesteryl ester (CE) content of aortas were generally lower in the SF group than in the BT group in comparison to the serum cholesterol levels. The dietary fatty acid pattern determined the fatty acid composition of CE in the serum and extracellular lipid of the aortic lesions. With regard to the intracellular changes of fatty acid pattern of CE (decrease in dienoic acid, predominantly linoleic acid, and increase in monoenoic acids, predominantly oleic acid, and in trienoic acids and higher unsaturated fatty acids), there were important differences between the 2 dietary groups. The dienoic acid content of CE decreased intracellularly from 61% to 30.5%, at the most, in the SF group, and then stopped. In the BT group only 26-35% dienoic acid was available from the extracellular CE and was reduced intracellularly to 9% at the most. In the SF group the intracellular increase in monoenoic acid content of CE was related to the decrease in dienoic acid content. In the BT group this was true only for some lipid deposits of the aorta; in other lesions the monoenoic acid content remained nearly constant or even decreased with decrease in linoleic acid whereas the increase in trienoic acid content was especially high suggesting that an unphysiological trienoic acid (20:3 delta 5, 8, 11), originating from oleic acid, was formed in greater amounts. Our findings point to the development of an essential fatty acid deficiency in the foam cells of aortic lesions in the BT group which may result in an unfavorable influence on the cholesterol clearance from the cells and the arterial wall.

Animals↗
PubMed1987

Suppression of aminoacyladenylate synthesis by methyl mercury in vitro and in vivo.

Methyl mercury (MeHg) at a concentration of 20 microM significantly inhibits the synthesis of aminoacyladenylates (AAA) in vitro from serine and histidine, and fails to inhibit AAA synthesis from phenylalanine, leucine, arginine and aspartate. In vivo administration of MeHg (single i.p. injection of 50 nmol/g body weight) leads to 75-80% suppression of AAA synthesis from serine, histidine, phenylalanine, leucine, arginine and aspartate in rat brain tissue.

Adenosine Monophosphate↗
PubMed1987

Modulation of messenger RNA metabolism in experimental methyl mercury neurotoxicity.

We have investigated the effects of methyl mercury of mRNA metabolism in mouse brain cells in vivo. It was demonstrated that methyl mercury substantially reduces the rate of synthesis of ATP and poly(A)-segments of mRNAs. The molecular sizes of poly(A)-segments isolated from hnRNA and polysomal mRNA of the experimental animal brain are smaller than the dimensions of the same segments from the cellular RNA of intact mice. A fall in the mRNA polyadenylation rate seen under methyl mercury directly correlates with reduced metabolic stability (t 1/2) of the respective poly(A)+mRNA. The mean time of nuclear-cytoplasmic transport of these mRNAs (t0 is substantially increased under methyl mercury. At the same time, methyl mercury has no effect on the metabolism of brain polysomal poly(A)-mRNA. Direct addition of methyl mercury to an in vitro system containing excess ATP failed to affect the activity of poly(A) polymerase isolated from the brain of intact mice. The poison-induced alterations in the poly(A)+mRNA metabolism bring about a considerable reduction of the poly(A)+-fraction's share in the total polysomal mRNA and dramatic fall in the intracellular polysomes concentration. All the alterations in the examined metabolic parameters well correlate both with a reduced ATP content in the brain tissue and decreased rate of total protein synthesis in brain cells. Proceeding from these results as well as data from the literature, we developed a hypothetical model of a general molecular mechanism whereby methyl mercury inhibits protein synthesis in the brain.

Adenosine Triphosphate↗
PubMed1987

Carnitine and experimental carbohydrate-induced hyperlipoproteinemia.

Carnitine, beta-hydroxy-gamma-trimethylaminobutyrate, plays an important role as a factor necessary for the transport of long-chain fatty acids into the mitochondria. In order to investigate the influence of L(--)-carnitine on hyperlipoproteinemias, the experimental model of the sucrose-induced hypertriglyceridemia of the rat was used. In these experiments L(--)-carnitine in the dose of 11 mg per day and 100 g body weight was able to antagonize the sucrose-induced hypertriglyceridemia and the increase of serum-free fatty acid level in female rats of the Wistar strain. Carnitine administration did not change the activities of lipogenic liver enzymes and the activity of post-heparin lipase. On the other hand, carnitine administration increased the rate of fatty acid oxidation in the liver. The main result of the study, i.e. the lipid-lowering effect of L-carnitine, suggests the use of this compound in the therapy of hyperlipoproteinemias.

Animals↗
PubMed1986

[Lipoprotein metabolism in relation to age].

Ageing is associated with a variety of changes of intracellular and extracellular lipid metabolism. Depending upon age the the rapidity of synthesis and metabolism of lipids decreases and partly increased plasma lipoprotein levels are found. Both under basal and under special alimentary conditions the lipoprotein metabolism shows age-dependent changes which may lead to an increased risk for atherosclerosis. These results are important for therapeutic and prophylactic conditions.

Adipose Tissue↗
PubMed1986

Fast estimation of ATP/ADP ratio as a special step in pharmacological and toxicological studies using the cell-free translation systems.

We have developed a simple and effective reversed-phase HPLC procedure for rapid estimation of the ATP/ADP ratio in a cell-free translation system containing creatine kinase. Analysis of the acetone-extractable pool derived from a reticulocyte lysate cell-free system was carried out by automatic chromatography on S5CN-ODS stationary phase using a linear 10-65% pyridine elution gradient formed on the basis of methanol/water (9:1, v/v) mobile phase. This method was used to detect and characterize the inhibition of translation induced by considerable suppression of ATP resynthesis in vitro. It was shown that methyl mercury, unlike cycloheximide, pactamycin, CCl4 and barbituric acid, exerts inhibitory effect on the ATP regeneration in a cell-free translation system.

Adenosine Diphosphate↗
PubMed1985

The response of some intravascular and intracellular lipid parameters of the rat after treatment with isatin.

The effect of isatin on serum lipid concentrations, the activity of lipoprotein lipase, the activity of lipogenic enzymes and the oxidation rate of fatty acids of female Wistar rats were investigated. A decrease of the triglyceride concentrations could be observed after one week of treatment of the group of sucrose-rich alimented animals, after two weeks this was also the case with the group fed with standard food. There were no changes in the cholesterol concentrations. Post-heparin lipolytic activity was not influenced. The liver enzymes malic enzyme, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase showed a remarkable increase in activity. The simultaneous rise of the oxidation rate of 14C-palmitate in the liver was measured. On the basis of the present findings the accelerated degradation rate could be responsible for the hypolipemic effect of the substance. The possible participation of the carnitine shuttle in the lipid-lowering action is discussed on the basis of changed concentrations of total carnitine, free carnitine and acylcarnitine in pooled serum samples after treatment with isatin.

Animals↗
PubMed1984

[HDL and LDL cholesterol changes in psychological stress in relation to stress experience].

During examinations and after a three-month examination period the changes of the parameters of fat metabolism were investigated depending upon stress experience before examinations. Students with a distinct stress experience showed a higher total cholesterol and LDL-cholesterol as well as a higher LDL/HDL-cholesterol quotient within a concrete examination. After the examination period in this group a higher LDL/HDL-cholesterol quotient and a lower HDL-cholesterol level was established in comparison to the group with an insignificant stress experience. A positive dependence on the initial value of the parameters of fat metabolism consists only in the group with distinct stress experience. According to these results also stress has an influence on the reactions of the fractions of cholesterol.

Adult↗
PubMed1983

[Beta 2 glycoprotein I analysis in patients with hyperlipoproteinemia, arteriosclerotic occlusive disease and diabetes mellitus].

Beta 2-glycoprotein-I (apolipoprotein H) is an activator of the lipoprotein lipase. The concentration of beta 2-glycoprotein-I in the blood serum was determined with the help of the radial immunodiffusion. In patients with hyperlipoproteinaemia of type IIa and IIb, arteriosclerotic obstructive disease or diabetes mellitus the beta 2-glycoprotein-I-concentrations were increased. In hyperlipoproteinaemia of type IV can be concluded to a relative beta 2-glycoprotein-I-deficiency.

Adolescent↗