Biomedical subjects
Publications and source records attributed to G Lusztig.
Prehomogeneous vector spaces arising from semisimple groups are considered, and it is shown that certain local systems on the open orbit have the property that their middle extension is zero on the complement of the open orbit.
I construct a canonical basis in the tensor product of a simple integrable highest weight module with a simple integrable lowest weight module of a quantized enveloping algebra. This basis is simultaneously compatible with many submodules of the tensor product. As an application, I obtain a construction of a canonical basis of (a modified form of) the quantized enveloping algebra.
It has been supposed that prostacyclin (PGI2) and its analogues have important antiatherogenic effects. The aim of this work was to test the effect of PGI2 and 7-oxo-PGI2- (a stable analogue of PGI2) (6) treatment on the acyl CoA: cholesterol-acyltransferase (ACAT) activity in the aortic wall of rabbits. The rabbits had been previously fed with cholesterol and treated with PGI2 and 7-oxo-PGI2 intravenously. Cholesterol feeding increased ACAT activity compared to the control group which was not fed with cholesterol: 16.84 nmol/mg prot./h and 10.03 nmol/mg prot./h, respectively. PGI2 treatment of the cholesterol fed group did not cause a significant decrease, while 7-oxo-PGI2 treatment significantly decreased aortic ACAT activity compared to the cholesterol-fed control group; 14.31 nmol/mg prot./h; 11.53 nmol/mg prot./h and 16.84 nmol/mg prot./h, respectively. The decrease found in the ACAT activity after PGI2 and 7-oxo-PGI2 treatment are new data for the protective effect of these agents against atherosclerosis.
The ability of macrophage-derived foam cells to migrate from atherosclerotic lesions represents one potential mechanism for the regression of atherosclerosis. It is, however, generally recognized that the transformation of macrophages into foam cells results in greatly reduced migrational ability. In the present study, we set out to investigate the factors affecting migratory capability in foam cell-like cells with the use of an in vitro assay. Foam cell-like cells were prepared by incubating macrophages in the presence of oxidized low density lipoprotein (LDL). The transformation to a typical foam cell morphology was demonstrated by Nile red staining (light microscopy), and the mechanisms of binding, uptake, and intracellular processing of oxidized LDL were established by colloidal gold labeling on the ultrastructural level. With the in vitro assay, the migration of these foam cell-like cells was found to be markedly inhibited compared with untreated, control macrophages. However, zymosan-activated mouse serum restored migration in oxidized LDL-treated cells to levels similar to those of control cells. Restoration of migratory capacity was accompanied by alterations in the cytoskeleton system, especially in actin arrangement.
6-keto-prostaglandin F1a and thromboxane B2 were determined by radioimmunoassay in 135 healthy children, as a control group, and in 125 offsprings of parents suffering from premature coronary artery disease. Plasma prostacyclin concentration had decreased in children with a positive family history of coronary artery disease. It was demonstrated a strong reduction of thromboxane level in boys from age 11 in endangered group while the thromboxane/prostacyclin ratio did not differ from the control. It was supposed that in adolescent sons of parents who have had an acute myocardial infarction before the age of 45, a compensatory mechanism exists to protect them from disturbances in regulation of the balance between prostacyclin and thromboxane.
Our experiments aimed at the in vitro development of cells similar to macrophage foam cells of vessel wall. Fatty macrophages were produced by Intralipid incubation of peritoneal macrophages and their motility was studied in vivo. Our results showed that fat-saturated, isotope and colloid-gold marked macrophages can get through the vessel wall, so they are able to in vivo migration.
An account is given of possibilities and mechanisms of regression of arteriosclerosis. Reference is made to animal experiments and to angiographic investigations of man, and the assumption is derived that even in man arteriosclerosis is to a certain extent capable of regression. This view applies preferentially to lipidous alterations. A distinction is made between two mechanisms underlying regression. One of them is attributed to reduction of existing hypercholesterolaemia, while the other is related to regression via action of so far unknown wall factors, without lowering of blood cholesterol.
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Atherosclerosis is-even in advanced state--able to regression and this event may occur under certain circumstances. Regression can be of such size, as to lengthen significantly life of patient, relieving essentially his complaints. This regression may be increased by drugs and promoted with alteration of life-circumstances.
The authors checked the mineral content of the abdominal aorta in 73 men and women against their calcium content of hair in autopsy material. It was stated that decreased level of haircalcium considerably precedes the start of the calcification process in vessels, thus its measuring may call attention to balance troubles of calcium metabolism in time. Despite the picture generally formed and considered to interpret the results uniformly, it was observed that if the calcium level of hair and the abdominal aorta calcium content, as well as the general sclerotic state are examined in the case of the same diseased person, they may not be in accordance sometimes. This can be in connection with the subjective determination of the general sclerotic state of the deceased person. This also seems to support the measurement of changes in the calcium content of hair, preceding arteriosclerotic organic manifestation. Finally, in their study the authors are dealing with mutual connections of the calcium content of hair and some trace elements of the aorta, as well as with relations of aortic trace elements to one another.
Our approach serves several purposes: To demonstrate the response of aortic cell nuclei to a changing environment (e.g. hypercholesterolemia, experimental diabetes, drug treatment), to apply the acridine orange (AO) ultracytochemical method, and to determine the euchromatin/heterochromatin (EU/HET) ratio by morphometric procedures as suitable criteria, and to emphasize the differential nuclear activity of adventitial cells. Hypercholesterolemia in rabbits results in an increase of AO positive nuclei in the adventitia. Additional treatment with tinofedrine, a new cerebral vasodilator drug, reveals an even higher number of AO positive nuclei in adventitial and also in endothelial and plaque cells. In streptozotocin induced diabetes in rats the increased number of AO positive cells coincides with an elevated EU/HET ratio.
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Rabbit aortic changes were investigated after different sclerogenic diets. A subintimal chondroitin sulfate layer was characterized by toluidine blue metachromatic staining at pH 1--3, CEC value expressed in MgCl2 concentration: 0.4M, hyaluronidase sensitivity. This layer becomes disorganized during plaque formation and partly disaappears. A long-lasting sclerogenic diet, as well as a diet containing several sclerogenic factors, produced an increase of frequency and extension of the media necrosis, calcification, and chondroid metaplasia of the aortic wall. In these lesions, an increase of mucopolysaccharide secretion of modified smooth muscle cells was observed.
Authors by a new combined diet consisting of cholesterol vitamin D3 and sour cream produced clinico-biochemical changes characteristic for atherosclerosis in a very short period in rabbits. This diet caused severe lipoproteinaemia, hypercholesterinaemia and microscopis and macroscopic changes in the aortic wall. Authors assume, that this diet is suitable for producin atherosclerosis in a short period.
10 rabbits underwent a cholesterol feeding. 10 rabbits were used as control animals. After 12 weeks in the tissue extract of the intima-media-complex of the aorta as well as in the serum the total lipids and the total cholesterol were determined. On histological preparations the thickness of the adventitia of the aorta was measured. In comparison to the control group the animals fed with cholesterol showed a significant increase of the lipid values in the serum and the aorta as well as of the thickness of the adventitia. However, no connections could be proved between the parameters of the serum lipids and the morphological changes of the adventitia.
Correlation between the changes of blood cholesterol and lipoid level, exerted by cholesterol feeding and changes of the thickness of the aortic wall was investigated. Changes have been found to be significant, but as it was revealed by investigation of regression no correlation exits between them. Authors believe that thickening of the adventitia in atherosclerosis is a consequence of the morphological changes of the vessel-wall.
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