Homocysteinemia and endothelial damage after methionine load.

Homocysteinemia increased significantly after a methionine load of 50 mg/kg in patients with peripheral artery occlusive disease but this load was insufficient to increase circulating endothelial cell count as a marker of endothelial damage. Only after an increased load of 100 mg/kg methionine circulating endothelial cells also increased markedly confirming the results of a previous experimental study. These data indicate a threshold concentration of homocysteine in blood necessary to induce endothelial lesions.

Lack of evidence for the interaction between renin-angiotensin-aldosterone system and endothelin in vivo.

Aim of the study was to reveal the possible factors regulating plasma endothelin (ET) levels in vivo in patients with essential hypertension (EH) by the simultaneous determination of plasma renin activity (PRA) and plasma aldosterone (ALD). In addition, the possible relationship between ET and circulating endothelial cells as a marker of endothelial damage was also investigated. The postural test revealed a significant increase of ET levels (26.

[The antiphospholipid syndrome and atherothrombosis].

The antiphospholipid antibody syndrome is an autoimmune disease which attracts in recent years increasingly the attention of angiologists and cardiologists. Although it is manifested as regards laboratory indicators as a circulating anticoagulant, somewhat paradoxically clinicians observe only a marked tendency towards venous and arterial thromboses at different sites. The condition is frequently encountered in young people with idiopathic and recurrent diseases.

[Lipoperoxides and their clinical importance].

Background: Research and investigations in the sphere of lipid peroxides has been pursued so far for a relatively short time. Therefore every new finding is a great asset for this branch of medicine. An elevated lipid peroxide level signalizes pathological changes in the organism.

Homocysteine theory of atherosclerosis.

A short survey is presented of the homocysteine theory of atherosclerosis with the key role of endothelial injury. Hyperhomocysteinaemia is a newly emerging risk factor of atherosclerosis. Both hereditary and nutritional influences may contribute to its occurrence.

[Heparan sulfate and its function in the endothelium].

The author presents an account of the main contemporary findings on the functional importance of heparan sulphate (HS), which is an important part of the endothelial glycocalyx. Based on the ability to form complexes with proteins, HS interferes in particular with antithrombotic properties of the endothelium and modulates in a significant way the proliferative activity of the endothelium and other cells of the vascular wall. The author mentions its pathogenetic role, possibilities of its diagnostic use and therapeutic perspectives in the area of vascular diseases.

[Electric conductivity of erythrocyte sediments and red blood cell deformability].

Background: To assess the deformability of erythrocytes several methods can be used. The latter investigate either the properties of single blood cell or the properties of a red cell suspension. The objective of the present study was to assess whether experimentally induced deterioration of the red cell deformability can be recorded by measurements of the electric conduction of red cell sediment.

Increase of endothelaemia in psoriasis.

Changes of blood vessel endothelium in psoriasis have not been fully documented in the literature. The aim of our study was to ascertain whether in cases of such involvement an increase of endothelaemia could be identified. The counts of circulating endothelial cells were significantly increased in psoriatics compared with healthy individuals and patients with atopic eczema.

Heparan sulfate as a venostatic endothelial stabilizing factor.

A humoral transfer of a factor inducing a decrease of circulating endothelial cells (CEC) released during venostasis was demonstrated in rats. The possibility to block its activity by an in-vitro addition of protamine suggests its identity with an endogenous heparan sulfate possessing an inhibitory effect on endothelial turnover. This was supported by an analogous effect of intravenously administered heparan sulfate-related agent.

[Lipoperoxides and atherosclerosis].

The theory of the pathogenetic role of lipoperoxides in atherosclerosis and thrombosis is very topical at present. It unifies the theory on the role of free oxygen radicals with the theory of damage of the vascular wall and with the theory of impaired lipid metabolism. It makes possible also a new interpretation of known risk factors.

Antithrombotic effects of heparin and related agents.

Native heparin was very effective in models of arterial and venous thrombosis as well as in a model demonstrating the effect on endothelial stability in rats. The effect on venous thrombosis was particularly prominent. The activities of LMW-heparin were about the same in all three models, the absolute effective dose against arterial thrombosis being much lower than with native heparin.

The effect of polyamines on the endothelium and vascular wall metabolism in the rat.

Administration of putrescine, a polyamine, to rats leads to endothelial injury manifesting itself by an increased number of endothelial cells circulating in blood. Moreover, putrescine affects the metabolism of the arterial wall itself, primarily by increasing the activity of phosphomonoesterases I and II and by decreasing the activities of Krebs cycle enzymes, both of which are phenomena that can be regarded as "preatherogenic" changes 5, 6, 8, 11 preceding the onset of pathological processes in the arterial wall. Putrescine significantly decreases aortic ATPase (adenylpyrophosphatase) both in the acute and chronic phases of experiment.

Antithrombotic activity of an unsaturated fatty acid preparation.

An unsaturated fatty acid preparation from fish oil, "Epavit", completely prevented arterial thrombosis induced in the rat aorta by a combined stenosis, extensive endothelial perturbation and i.v. serotonin, at an optimum dose of 0.

Endothelial lesion in hypertension.

A method for indicating latent endothelial lesion based on circulating endothelial cell count after methionine challenge was used in a group of hypertensives and in healthy controls. A significantly increased cell count was found in hypertensives.

The role of endothelium in the pathogenesis of vascular diseases.

In connection with the increasing importance of the endothelium in understanding the pathogenesis of vascular diseases, new types of mediators originating in the endothelium are described, such as EDRF and endothelin. The method of endothelial cell cultivation has contributed to their detection. Besides such analytical methods, a more global in vivo aspect of endothelial function is dealt with by the method of counting circulating endothelial cell carcasses in blood applicable also clinically.

Endothelium in the pathogenesis of main vascular diseases.

An attempt was made to show that a special methodology based on functional in vivo aspects (induction of increased enothelemia by suitable challenges) may help to obtain an integrated and potentially useful new look at both the pathogenesis and therapy of thrombosis and atherosclerosis.

Metabolic changes in the arterial wall and endothelial injury in experimental methioninaemia.

Chronic administration of methionine to rats induced endothelial lesion manifested by increased endothelaemia and metabolic changes indicative of pathological processes involving the vessel wall. These changes did not spontaneously return to values observed in control animals. Long-term administration of antiatherosclerotic drugs Pyridinolcarbamate and Phtalazinole II normalized metabolic disorder in the aortic wall and reduced endothelaemia to normal values.

Models of thrombosis.

A critical review is presented on animal models of thrombosis. After a glance at the pathogenesis of clinical thrombosis and its multifactorial character, the classification, aims and a suggested rational design of thrombosis models are advanced and illustrated by some examples of an attempted solution of this complex problem.

Antithrombotics in view of thrombosis models.

Two highly sensitive models of arterial and venous thrombosis forming with the test of endothelial stability a complementary system with a maximum stress on the role of vascular lesion were used to test a series of four antithrombotic drugs (heparin, acetylsalicylic acid, dipyridamole, sulfinpyrazone) and four drugs with other indications but with an antithrombotic activity in experiment (prenylamine, troxerutin, ketanserin and pizotifen). All drugs, except heparin, were given orally. Whereas heparin, aspirin and prenylamine had mixed effects on both arterial thrombosis (i.

A sensitive model of venous thrombosis in rats.

Several antithrombotics (heparin, acetylsalicylic acid, sulfinpyrazone and dipyridamole) as well as an antiserotonin ketanserin were tested in a new sensitive model of venous thrombosis in rats. Intravenous injection of hypotonic saline was used for thrombus induction combined with the vena cava ligation. Formation of thrombi was evaluated by their weights.

The effect of antithrombotics in a new model of arterial thrombosis.

A series of drugs representing several groups of antithrombotics was tested in a new model of arterial thrombosis in rats. Thrombosis was produced in the aorta by the combination of local partial obstruction and systemic administration of hypotonic saline with serotonin. High efficacy was demonstrated with heparin, acetylsalicylic acid, troxerutin, prenylamine, antiserotonin agents /pizotifen, ketanserin/ and particularly with the combinations of antiserotonins and the above mentioned antithrombotic drugs.

A new model of arterial thrombosis.

A new model of arterial thrombosis in rats was based on a combination of a localizing hemodynamic factor /partial mechanical constriction of aorta/, generalized mild endothelial lesion /i.v.hypotonic saline/ and a humoral factor/i.