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ABSTRACT: A modification of von Willebrand' factor/ristocetin cofactor activity test is proposed. Agglutination of formalin-treated platelets is monitored in the aggregation analyzer from changes in the light transmission in the specimen. The test is sensitive and reproducible. It is intended for clinical laboratories to be used in patients with hematological diseases and the endotheliopathy syndrome of different etiology.
Klinicheskaia laboratornaia diagnostika 04/1998;
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Klinicheskaia meditsina 02/1995; 73(1):20-2.
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ABSTRACT: Functional platelet characteristics were studied in hypertensive subjects having episodes of silent myocardial ischemia. A total of 36 patients with essential hypertension (EH) stage II (WHO criteria, 1979) underwent echocardiography and 24-h ECG monitoring. Platelet aggregation induced by adenosine diphosphate was assessed by laser aggregation analyzer. It is demonstrated that platelet aggregation in EH patients with silent ischemia was increased 5-fold as compared to healthy subjects and 2-fold versus EH patients without ischemia. No significant differences existed between the two groups by such parameters as systolic or diastolic pressure and left ventricular myocardial mass. An involvement of elevated platelet aggregation can be suggested in the genesis of coronary insufficiency in EH associated with episodes of silent myocardial ischemia.
Terapevticheskii arkhiv 02/1994; 66(11):72-5. · 0.14 Impact Factor
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ABSTRACT: Nifedipine antihypertensive effect was evaluated in 20 patients with essential hypertension. It was found to depend on pretreatment values of ADP-induced platelet aggregation response. The latter was studied with a new method of laser measurements of the aggregate radius sizes.
Terapevticheskii arkhiv 02/1993; 65(12):19-22. · 0.14 Impact Factor
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ABSTRACT: The basic differences between sialylated (sialic acid rich) and desialylated (sialic acid poor) human low density lipoproteins (LDL) are not fully defined. It is not known whether there are any differences in the LDL composition of coronary atherosclerosis patients and healthy individuals.
Sialylated (45 to 94% of total LDL) and desialylated (6 to 55%) LDL were separated by affinity chromatography on Ricinus communis agglutinin-agarose, and their chemical composition and physical properties were examined.
Sialic acid contents in sialylated LDL fractions of healthy subjects and patients were the same and 1.5 to 3-fold higher than in desialylated LDL. Desialylated LDL had smaller sizes and greater electrophoretic mobility than sialylated ones. Desialylated, but not sialylated LDL, induced 1.5- to 4-fold accumulation of neutral lipids in human aortic smooth muscle cells and human blood monocytes. Subfractions of desialylated LDL containing lower amount of sialic acid revealed higher ability to accumulate lipids in cultured cells. Desialylated LDL contained lower amounts of cholesteryl esters, free cholesterol and triglycerides as compared with sialylated LDL. On the other hand, concentration of di-, monoglycerides and free fatty acids in desialylated LDL was 2 to 3-fold higher than in sialylated lipoproteins. Desialylated LDL fraction was characterized by lower levels of phosphatidylcholine, sphingomyelin, phosphatidylethanolamine, but higher content of lysophosphatidylcholine. Freshly isolated sialylated and desialylated LDL contained equal amounts of thiobarbituric acid reactive substances, but oxidation of desialylated LDL was more pronounced in presence of Cu(2+)-ions. Desialylated LDL had higher level of oxysterols and lower amounts of vitamin A and E. Content of free amino groups of lysine in desialylated LDL of patients was 2-fold lower than in sialylated LDL. This difference was partially due to masking of amino groups caused by conformational change in the tertiary structure of apolipoprotein, partially to chemical modification of amino groups. When subfractionated by density gradient ultracentrifugation, desialylated LDL was represented by higher density particles than sialylated LDL. Sialic acid content in desialylated LDL subfractions decreased with rise of lipoprotein density. Higher density desialylated LDL and in less extent sialylated LDL contained smaller amounts of free and esterified cholesterol and phospholipids. Only the densest subfractions of desialylated LDL from healthy subjects caused intracellular lipid accumulation. Ability of patients' desialylated LDL to accumulate cholesterol in cells increased with particle density.
Extensive biochemical and biophysical analysis performed in this study shows that desialylated LDL differ from these sialylated LDL in many respects. The LDL of coronary atherosclerosis patients differ from those in healthy individuals in several parameters.
Laboratory Investigation 12/1992; 67(5):665-75. · 3.64 Impact Factor
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ABSTRACT: Low density lipoprotein (LDL) from patients with coronary atherosclerosis and diabetes mellitus as well as in vitro desialylated LDL, glycosylated LDL, and lipoprotein (a) caused a twofold to fourfold rise in cholesteryl ester in cultured human blood monocytes and intimal smooth muscle cells isolated from normal aorta. Native LDL from healthy subjects failed to induce intracellular lipid accumulation. We have demonstrated by laser correlative photometry and gel filtration chromatography that in vivo and in vitro modified lipoproteins form aggregates under cell culture conditions. The degree of modified lipoprotein aggregation directly correlated with the ability of these lipoproteins to elevate the cholesteryl ester content of cultured cells. Modified lipoprotein aggregates isolated by gel filtration induced a threefold to fivefold elevation in cellular cholesteryl ester content. Aggregates of 125I-modified LDL were taken up and degraded fivefold to sevenfold more effectively as compared with nonaggregated lipoproteins. The uptake and degradation of 125I-labeled aggregates were strongly inhibited by unlabeled aggregates, latex beads, and cytochalasin B but not by native or acetylated LDL. These data indicate that uptake of lipoprotein aggregates occurred by phagocytosis. Obtained results suggest that modified lipoprotein aggregation may be the key condition for lipid accumulation.
Circulation Research 08/1992; 71(1):218-28. · 9.49 Impact Factor
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ABSTRACT: Investigations were conducted to determine whether rabbit aortic smooth muscle cells (SMC) reproduce their essential in situ features in culture. Enzymatically isolated cells in culture were compared with their in situ state in terms of myosin and caldesmon isoform expression, sensitivity to Ca(2+)-mobilizing agonists, and contractility. Protein marker expression was assessed by electrophoresis and quantitative immunoblotting, and intracellular free Ca2+ ([Ca2+]i) measurements were accomplished using indo-1, a Ca(2+)-sensitive fluorescent dye. Contraction of SMC grown on deformable silicone films was monitored optically. Before the onset of cell division (3 to 6 days in culture), SMC still contained significant although decreasing amounts of smooth muscle myosin (SM1 and SM2 isoforms) and they started to express nonmuscle-type myosin. The relative content of 150-kDa caldesmon decreased, whereas the expression of 77-kDa caldesmon increased during this period. In the confluent primary culture (11 days), SM1 was expressed, but 150-kDa caldesmon was hardly detectable. Histamine (10(-5) mol/L), serotonin (10(-6) mol/L), and thrombin (1.5 units/mL) contracted deendothelialized rings of rabbit aorta, but only histamine was able to elevate [Ca2+]i 2.5- to 3-fold and induce reversible contraction of primary nondividing cells. [Ca2+]i elevation in response to histamine was due both to Ca2+ mobilization from intracellular stores and Ca2+ flux across the plasma membrane. After the onset of proliferation, SMC regained the ability to elevate [Ca2+]i in response to serotonin and thrombin but lost the ability to contract. Thus, primary cultured quiescent rabbit aortic SMC (3 to 6 days in culture) retain the essential features of vascular SMC in situ (eg, smooth muscle specific contractile and regulatory proteins, vasoactive hormone sensitivity, and contractility).
American Journal of Hypertension 07/1992; 5(6 Pt 2):124S-130S. · 3.18 Impact Factor
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ABSTRACT: The aim of this study was to determine the significance of the "coronary factor" in patients with essential hypertension (EH). Electrocardiogram Holter monitoring was performed in 61 patients with EH stage II (according to the World Health Organization criteria). Silent, ie, painless ST-segment depression, was found in 34 patients on whom echocardiography, a treadmill test, and transesophageal pacing were performed. In 21 patients with EH and silent ischemia, the examination included 201Tl stress scintigraphy, coronary angiography, and a platelet aggregation test. In 15 patients, catecholamines and beta-endorphins were obtained in blood samples during silent ischemia. 201Tl scintigraphy showed transient defects of perfusion without clearance abnormalities (group I) and with clearance abnormalities (group II). The patients in group I had more severe left ventricular hypertrophy (LVH) and a significantly higher platelet aggregation response to 0.5 mumol/L adenosine diphosphate; one patient in this group had coronary atherosclerosis. LVH and the platelet aggregation response was less pronounced in the patients in group II, but atherosclerotic lesions of a coronary artery were observed in four patients. In both groups, norepinephrine and beta-endorphin levels were increased during silent episodes of ischemia. The results suggest that there are different pathogenetic mechanisms of coronary insufficiency in patients with EH, a hypertensive heart, and silent ischemia.
American Journal of Hypertension 07/1992; 5(6 Pt 2):169S-174S. · 3.18 Impact Factor
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ABSTRACT: Blood monocytes or intimal smooth muscle cells from normal aorta were incubated with low density lipoprotein (LDL) from patients with coronary atherosclerosis, or with LDL from diabetic patients, or with lipoprotein(a) (Lp(a)). In each case there was a 2- to 4-fold rise in the intracellular cholesteryl ester content. LDL from healthy subjects failed to induce intracellular lipid accumulation in these cells. LDL from patients with coronary atherosclerosis, LDL from diabetic patients, and Lp(a) form aggregates under cell culture conditions. The ability of these lipoproteins to increase the cholesteryl ester content of cultured cells is directly correlated to the degree of lipoprotein aggregation. When aggregates were removed from the lipoprotein preparations by filtration, the latter became less effective in promoting intracellular lipid accumulation. Incubation of cells with lipoprotein aggregates, isolated by gel filtration, induced a 3- to 5-fold elevation of the cellular cholesteryl ester content. These results suggest that LDL from atherosclerotic patients, or LDL from diabetic patients, or Lp(a) have a tendency to form aggregates and that these aggregates are avidly taken up by intimal smooth muscle cells followed by lipid accumulation. This aggregation tendency may play a role in atherogenesis.
European journal of clinical chemistry and clinical biochemistry: journal of the Forum of European Clinical Chemistry Societies 05/1992; 30(4):171-8.
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ABSTRACT: Holter monitoring was performed in 61 patients with essential hypertension. Painless, silent ST segment depression was found in 34 patients. Exercise myocardial scintigraphy indicated the occurrence of transient perfusion defects without abnormal clearance (Group 1) and those with abnormal clearance (Group 2). The patients from Group 1 showed more severe myocardial hypertrophy, higher platelet aggregation, coronary atherosclerosis was detected in 1 case. The patients from Group 2 exhibited less myocardial hypertrophy, lower platelet aggregation. Coronary atherosclerosis was revealed in 4 cases. The patients from the two groups had elevated plasma norepinephrine levels at the onset of silent myocardial ischemia.
Kardiologiia 03/1992; 32(2):26-30. · 0.20 Impact Factor
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Terapevticheskii arkhiv 02/1992; 64(8):39-43. · 0.14 Impact Factor
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Kardiologiia 02/1992; 32(1):66-7. · 0.20 Impact Factor
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ABSTRACT: Adenosine diphosphate (ADP)-induced platelet aggregation was studied in 59 patients suffering from essential hypertension, stages I and II (WHO, 1979) with different degree of left ventricular hypertrophy (LVH) by a new optical method. Using a laser aggregation analyzer the mean aggregate radius was measured in relative units. The left ventricular myocardial mass was estimated by echocardiography. Using laser aggregatograms the significant differences in aggregation responses were revealed with 0.5 microM ADP. In a group of patients without LVH, the aggregation response to 0.5 microM ADP did not differ from that in a group of healthy volunteers. With the growth of LVH from moderate to severe the response increased in succession. The same differences which were not, however, significant were observed with higher ADP concentrations. It was also found that the new method of laser aggregometry is more sensitive than the classic Born method.
Terapevticheskii arkhiv 02/1991; 63(12):50-3. · 0.14 Impact Factor
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ABSTRACT: Spontaneous aggregation of glycosylated, desialated, oxidized and malondialdehyde modified low density lipoprotein (LDL) as well as LDL of coronary heart disease patients has been discovered using methods for determination of light transmission fluctuations in suspensions and gel filtration. At the same time; LDL of healthy donors failed to aggregate under conditions of cellular culture. On the other hand, human aortic cells from unaffected intima incubated with modified LDL, but not native LDL of healthy donors, showed a rise in esterified cholesterol levels. There was a strong correlation between the degree of LDL aggregation and intracellular cholesterol ester accumulation (r-0.86, p 0.001, n-21). Removal of aggregates by passing preparations through and 0.1 um filter significantly inhibited the accumulation of cholesterol esters. The obtained data point to the essential, if not decisive, role of LDL aggregation in the processes of lipid accumulation by intimal cells in vitro.
Biulleten' eksperimental'noĭ biologii i meditsiny 08/1990; 110(7):34-6.
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ABSTRACT: A new approach to the investigation of the kinetics of platelet aggregation is described. The method is based on the analysis of light transmission fluctuations produced on the changes in the number of platelets in optical channel. The relative dispersion of the fluctuations of transmitted light intensity was used as a parameter to estimate the degree of platelet aggregation. Application of this method for the analysis of platelet aggregation permits to get new information about this process.
Biulleten' eksperimental'noĭ biologii i meditsiny 11/1989; 108(10):437-40.
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ABSTRACT: The study was undertaken to examine the status of the granular apparatus and platelet aggregability in 9 healthy donors and 18 patients with arterial hypertension (AH), including 14 with essential hypertension (EH) and 4 with symptomatic forms of AH. Among the patients, a group of 8 EH patients was singled out, who had, compared with normal, reduced relative volumes of electron dense platelet granules (from 17.9 +/- 2.0 to 5.3 +/- 0.6%). The group also showed lower platelet serotonin levels (from 67.3 +/- 5.3 to 17.6 +/- 3.7 ng per 10(8) cells; p less than 0.001) and a 2-fold decrease in the transport factor of acridine orange across the cytoplasmic and granular membranes as compared to normal. A positive correlation was established between the amounts of cellular serotonin and the relative volume of platelet granules (r = 0.850; p less than 0.001).
Kardiologiia 10/1989; 29(9):13-8. · 0.20 Impact Factor
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ABSTRACT: We have tested a hypothesis that aggregates of modified low density lipoproteins (LDL) play the key role in the accumulation of lipids by cells of unaffected aortic intima. It was demonstrated using analysis of relative dispersion of light transmission fluctuations as well as gel filtration on Sepharose CL-2B that LDL modified by oxidation, glycosylation, desialylation and malondialdehyde treatment form aggregates under the conditions of culture. Native LDL failed to aggregate under the same conditions. It was demonstrated that modified LDL, unlike native LDL, bring about a 2- to 3-fold rise in cholesteryl ester levels of cultured cells. Moreover, direct and strong correlation (r = 0.86) was observed between the degree of lipoprotein aggregation and the amount of cholesteryl esters accumulated. Removal of modified LDL aggregates by filtration through a 0.1 micron filter or gel filtration completely prevented the intracellular accumulation of cholesteryl esters. These findings indicate that LDL aggregates play an essential, if not the decisive, role in the intracellular accumulation of lipids in vitro.
Biochemical and Biophysical Research Communications 09/1989; 163(1):489-94. · 2.48 Impact Factor
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ABSTRACT: A new approach to the investigation of microaggregate formation kinetics in platelet suspension is described. The method is based on the analysis of light transmission fluctuations produced by the changes in the number of platelets in optical channel. The relative dispersion of such fluctuations (D) was used as a parameter to estimate the degree of platelet aggregation and to analyze the aggregation kinetics. It was found that a continuous recording of this parameter allows to detect microaggregate formation during spontaneous aggregation and aggregation induced by very low concentrations of ADP (0.05-0.15 uM) in platelet-rich citrate plasma. When 3-10 uM ADP was added to acid citrate-dextrose anticoagulated plasma at pH 6.5, microaggregate formation was detected by increase in D, whereas light transmission decreased by 15-20%. Analysis by scanning electron microscopy and the use of standard inhibitors of aggregation confirmed that in all these cases the microaggregate formation did take place.
Thrombosis Research 06/1989; 54(3):215-23. · 2.44 Impact Factor
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ABSTRACT: The new method for studies of the platelet aggregation kinetics is based on the creation of a platelet stream through the optic canal and on an analysis of fluctuations in the intensity of the luminous flux that has passed through the sample. The relative dispersion of fluctuations in the intensity of the light passed through the sample is suggested as a parameter for the estimation of the platelet aggregation and for analysis of their aggregation kinetics. The method permits recording the platelet aggregation in citrate plasma, enriched for platelets, after exposure to the inductor in very low concentrations (0.05-0.15 microM ADP). Scanning electron microscopy has shown that aggregates are indeed formed in such cases, and they can be recorded from the increase of the relative dispersion in the fluctuations in the passed light intensity but cannot be recorded by Born's optic method.
Laboratornoe delo 02/1989;
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ABSTRACT: The regulation of free cytoplasmic calcium concentration ([Ca2+]i) was studied in bovine pulmonary artery endothelial cells (BPAEC). The cells were seeded on the inner surface of glass cuvettes, grown to confluency and loaded with INDO-1. Using a multiwavelength method for estimation of [Ca2+]i it was shown that in Ca2+ containing medium a rapid rise of [Ca2+]i occurs in response to bradykinin, ATP or thrombin followed by a much slower decrease in free cytoplasmic calcium. Binding of extracellular Ca2+ by EGTA lowered basal [Ca2+]i but had no effect on the rate of agonist-induced [Ca2+]i increase or its absolute amount. In contrast, the kinetics of [Ca2+]i decrease were entirely different. A rapid (less than 0.5 min) decrease in [Ca2+]i to the basal level was observed immediately after the maximum had been achieved. If excess Ca2+ was added to the medium after EGTA, a second [Ca2+]i rise in response to the agonists occurred. The decrease in [Ca2+]i after the second peak was several times slower than the decrease in Ca2+ free medium. It is concluded that Ca2+ entry from the external medium had no effect on the maximal increase in [Ca2+]i but provides a severalfold increase in the duration the endothelial cell responses to the agonists.
Tissue and Cell 02/1989; 21(2):171-8. · 1.04 Impact Factor
