[Increase in GP IIb-IIIa and P2Y12 Receptors in Activated Platelets as the Possible Indicator of de novo Protein Synthesis].

Although platelets lack nuclei, they are capable of de novo protein synthesis. We speculate that key platelet receptors are involved in the regulation of this process, and the changes in their number indicate the de novo protein synthesis in platelets. The object of our study was native platelets obtained from healthy donors. Using flow cytometry and Western blot, we determined the number of GP IIb-IIIa receptors (fibrinogen receptor) and P2Y12 receptors (ADP receptor) on the surface of platelets upon their activation with ADP and collagen. To verify the approaches and techniques used, we studied IL-1ß protein, which was previously shown to be synthesized de novo in activated platelets. GP IIb-IIIa receptor numbers correlate with the number of P2Y12 receptors on the cell surface (R = 0.45, p = 0.03). It was demonstrated that the platelet receptor numbers are higher on the surface of the cells with high functional activity. According to the data obtained by Western blot, upon the cell activation with ADP, the number of GP IIb-IIIa and P2Y12 receptors increases, which may serve as evidence of these proteins being synthesized in the activated platelets. It was observed that the level of P2Y12 and IL-1ß was lower in the samples where GP IIb-IIIa receptor was blocked by the selective inhibitor, i.e., the Fab fragment of the antibodies that specifically recognizes the GP IIb-IIIa complex. This suggests the important role of GP IIb-IIIa receptor in the regulation of protein synthesis.

[THE NEW APPROACH TO EVALUATION OF ENDOTHELIUM DYSFUNCTION: DETECTION OF NUMBER OF CIRCULATING ENDOTHELIUM CELLS USING FLOW CYTOMETRY TECHNIQUE].

The endothelium dysfunction takes leading place in pathogenesis of development of cardiovascular diseases. The circulating endothelium cells of peripheral blood can act as a direct cell marker of damage and remodeling of endothelium. The study was carried out to develop a new approach to diagnose of endothelium dysfunction by force of determination of number of circulating endothelium cells using flow cytometry technique and to apply determination of circulating endothelium cells for evaluation of risk of development of ischemic heart disease in women of young and middle age. The study embraced 62 female patients with angiography confirmed ischemic heart disease, exertional angina pectoris at the level of functional class I-II (mean age 51 ± 6 years) and 49 women without anamnesis of ischemic heart disease (mean age 52 ± 9 years). The occurrence of more than three circulating endothelium cells by 3 x 105 leukocytes in peripheral blood increases relative risk of development of ischemic heart disease up to 4 times in women of young and middle age and risk of development of acute myocardial infarction up to 8 times in women with ischemic heart disease. The study demonstrated possibility to apply flow cytometry technique to quantitatively specify circulating endothelium cells in peripheral blood and forecast risk of development of ischemic heart disease in women of young and middle age depending on level of circulating endothelium cells.

[Factors influencing platelet aggregation in patients with acute coronary syndrome].

AIM: To study factors influencing platelet aggregation in patients with acute coronary syndrome (ACS). SUBJECTS AND METHODS: The investigation enrolled 147 patients with ACS. Their blood was sampled on days 1, 3-5, and 8-12 days after the onset of ACS. All the patients received acetylsalicylic acid (ASA) 300 mg on day 1, then 100 mg/day and clopidogrel 300-600 mg on day 1, then 75-150 mg/day. Platelet aggregation was analyzed in 65 patients on day 1 after ASA intake, but prior to clopidogrel therapy. The aggregation was induced by 5 and 20 pmol of ADP. RESULTS: With the use of clopidogrel 75 mg/day on day 3-5, platelet aggregation was reduced by 2.1 and 1.7 times for 5 and 20 µmol of ADP, respectively, as compared to day 1 (ASA without clopidogrel) and remained unchanged on days 8-12. Increasing the dose of clopidogrel up to 150 mg/day potentiated its antiaggregatory effect. On day 1 (ASA without clopidogrel), there was a direct correlation between platelet aggregation levels and mean platelet volume (MPV) (correlation coefficients (r), 0.526 (p < 0.001) and 0.368 (p = 0.015) for 5 and 20 µmol of ADP, and between platelet aggregation levels and glycoprotein (GP) IIb-IIIa (r = 0.387; p = 0.002 and r = 0.411 (p < 0.001) for 5 and 20 µmol of ADP. No similar correlations were found on days 3-5 and 8-12 of administration of ASA and clopidogrel. The genetic polymorphism of GP lIb-Illa (GP Ila Leu33Pro) was not noted to affect platelet aggregation. Examining the effects of genetic variations in cytochrome P450 isoform CYP2C19 (a clopidogrel metabolizer) revealed the enhanced aggregation stimulated with 20 µmol of ADP in the carriers of slowly clopidogrel-metabolizing haplotype of CYP2C19 (differences were found on days 3-5 as compared to rapidly and routinely metabolizing haplotypes). CONCLUSION: In the patients with ACS, platelet aggregation is influenced by MPV, GP IIb-IIIa levels, and CYP2C19 polymorphism and is not by GP IIb-IIIa polymorphism.

[Gender differences in clinical and hemoreologic disorders in elderly patients with non-cardioembolic ischemic stroke].

Clinical manifestation and platelet homeostasis parameter results in elderly patients with atherothrombotic and lacunar strokes are presented. There is platelet activation in these patients manifested by increasing of P-selectin expression in response to adenosindiphosphate induction on flow-cytometry. Agregometry method was not informative for platelet activity estimation in these patients. Von Willebrand factor receptor expression on the platelet may have prognostic value for acute period. The fibrinogen receptor expression on the platelet was increased in women with stroke comparing with men.

Glycoprotein IIb-IIIa content and platelet aggregation in healthy volunteers and patients with acute coronary syndrome.

Glycoprotein (GP) IIb-IIIa (αIIbß3-integrin) is the central receptor of platelet aggregation. Activated GP IIb-IIIa binds fibrinogen or von Willebrand factor, which forms molecular bridges between aggregating platelets. This review summarizes data on the relationship between GP IIb-IIIa expression on the platelet surface and platelet aggregating activity. GP IIb-IIIa number, measured as maximal binding of complex-specific monoclonal antibody, varied by approximately two fold in both healthy volunteers (n = 35) and patients with acute coronary syndrome (ACS) (n = 65). In healthy volunteers positive associations were observed between GP IIb-IIIa number and the level of ADP-induced aggregation when this relationship was analysed in untreated platelet-rich plasma (PRP) as well as upon in vitro addition of aspirin or non-saturating concentrations of GP IIb-IIIa blockers. In the same group of volunteers almost no differences in aggregating activity were detected between donors carrying the GP IIIa Pro33 allele (n = 15) and those with the GP IIIa Leu33Leu33 genotype (n = 20). No significant relationships were revealed between platelet aggregability and variations of plasma fibrinogen concentration. Positive correlation of the level of ADP-induced aggregation and GP IIb-IIIa content was detected in patients with ACS within the first hour upon admission to the hospital when they had already received aspirin, but not clopidogrel. However, there were no correlations between these parameters at days 3-5 and days 8-12 (before discharge). At these time points patients were treated not only with aspirin but were saturated with clopidogrel as well. In ACS patients we also evaluated the expression of another platelet adhesive receptor, GP Ib, and found a significant positive correlation between GP IIb-IIIa and GP Ib content. A strong association was also revealed between the number of both receptors and mean platelet volume. The latter observation indicated that individual variations of the number of glycoprotein molecules are mainly affected by platelet size but not the density of their expression on the platelet membrane. Possible usefulness of measuring GP IIb-IIIa content as a marker of increased platelet reactivity is discussed.

[Integral tests of the hemostasis system in assessing the efficiency of acetylsalicylic acid in patients with ischemic heart disease]. / Integral'nye testy sistemy gemostaza v otsenke éffektivnosti atsetilsalitsilovoi kisloty u bol'nykh ishemicheskoi bolezn'iu serdtsa.

Despite the fact that acetylsalicylic acid (ASA) is the "gold" standard for the prevention of cardiovascular complications in patients with coronary heart disease (CAD), a number of patients still have risks of atherothrombosis. In the present study, the antithrombotic effect of ASA in patients with CAD was assessed in platelet-rich plasma (PRP) using integral tests of the hemostasis study: the T-TAS system (Total Thrombus-formation Analysis System) and the thrombin generation test (TGT). The study involved 34 patients with stable CAD (11 women, 23 men) and people (15 women, 18 men) in the control group. As a result of assessing the activity of thrombus formation using the T-TAS system, a significant decrease in the area under the curve (AUC10) was found in the group with CAD patients compared with the control (135.6 [88.0-222.3] and 260.5 [217.3-301.9], respectively, p.

[Clopidogrel resistance in patients with acute coronary syndrome].

AIM: to reveal the frequency of clopidogrel resistance in patients with acute coronary syndrome (ACS) and its impact on prognosis in these patients. SUBJECTS AND METHODS: Seventy-five clopidogrel-treated patients with ACS were followed up. Optical aggregometry was conducted using ADP 20 micromol. The resistance criteria were baseline platelet aggregation, platelet aggregation on day 7, % < 10%. Inflammatory markers (IL-6, IL-10, and C-reactive protein) were determined. Genetic polymorphisms (the IIIa subunit gene--Leu33Pro, the receptor P2Y(12) C18T and G36T gene, and the CYP3*A4(A-293G) gene) were studied. RESULTS: According to the accepted resistance criteria, 54 (72%) patients were sensitive to clopidogrel and 21 (28%) were resistant to the agent. The resistance was revealed in 7 (23%) of the patients with ECG ST-segment elevation and in 14 (31%) of those with ST-segment elevation. Before admission to the clinic, the unresponsive patients had significantly more frequently received the loading clopidogrel dose of 300 mg while that latter was 600 mg in the responsive patients. As compared with the responsive patients, the unresponsive ones showed a significantly lower baseline antibody level that was increased on day 7. The clopidogrel resistance determined by this criterion had no impact on prognosis. On dividing the patients by aggregation quartile values, poor manifestations insignificantly more frequently occurred in the third and fourth quartiles. No clear correlation was found between the occurrence of clopidogrel resistance and the activation of an inflammatory process. The monozygous variant of the receptor P2Y(12) CT18T gene was insignificantly more frequently encountered in the unresponsive patients. CONCLUSION: The laboratory phenomenon of clopidogrel resistance exists. Large multicenter studies of this issue are needed to identify simple and least expensive resistance methods and clear diagnostic criteria that enable the findings to be compared.

[Genetic variants of platelet ADP receptor P2Y12 associated with changed platelet functional activity and development of cardiovascular diseases].

The key role in platelet aggregation is played by the platelet ADP receptor P2Y12, which is the target for antiaggregant drugs, clopidogrel and ticlopidine. At present, only sporadic data on genetic variants of platelet ADP receptor P2Y12 are available from literature, and their association with thromboembolic and cardiovascular diseases still remains obscure. Analysis of the group of subjects with high platelet reactivity resulted in identification of two nucleotide substitutions, C18T and G36T, in the coding region of the P2Y12 gene. The frequency of the P2Y12 T1 8 allele was higher in control group than in the group of patients survived from myocardial infarction at the age under 45 years (39% versus 28%, respectively, P = 0.04). Moreover, in the T18 carriers, platelet aggregation activity was lower than in the carriers of the wild-type genotype (0.84 +/- 0.05% versus 1.01 +/- 0.08%, respectively, P = 0.03). In the group of patients with early myocardial infarctions, a tendency towards the increased frequency of 16T allele in comparison with control group (20 and 12%, respectively, P = 0.07) was observed. The rate of ADP-induced platelet aggregation in the carriers of 16T allele from the control group was somewhat higher than in the subjects with the GG36 genotype (1.31 +/- 0.16% versus 1.12 +/- 0.06%, respectively, P = 0.07). The nucleotide substitutions identified were in absolute disequilibrium, i.e., allele T18 conformed to allele G36. On the contrary, allele C18 conformed to allele T36. Haplotype T18G36 was found to be responsible for the decreased risk of myocardial infarction and decreased platelet reactivity. It is suggested that polymorphisms of the P2Y12 gene identified can be used for determination of the risk group for myocardial infarction in the young males.

[Genetic risk factors for development of myocardial infarction in young men living in North-West region of Russia].

With the aim to detect genetic factors of risk of development of early myocardial infarction (MI) we studied 29 allele variants of 19 genes in 206 men who had survived MI in the age before 45 years and in 195 men of similar age without cardiovascular diseases. All subjects were inhabitants of North-West region of Russia. The following factors were associated with history of myocardial infarction: genotype RR191 of paraoxonase-1 (PON1) gene (RR 2.8 [95% CI: 1.24 - 6.30]), P1A2 allele of glycoprotein (GP) IIIa subunit of platelet fibrinogen receptor GPIIb/IIIa (RR 1.8 [95% CI: 1.11 - 2.93]), and Met145 allele of GPIbalpha platelet von Willebrand factor receptor gene. Genotype CC ( - 108) PON1 was associated with lowered risk of MI development (RR 0.6 [95% CI: 0.40 - 0.91]). During 7 years of follow-up 30 men from MI group died of recurrent acute coronary syndromes. In the group of those who died we noted increased prevalence of P1A2 GPIIIa allele compared with those who survived (p < 0.03). The results allow to suggest that contribute to development of MI in young men factors associated with elevation of functional state of platelets and levels of oxidized lipids in blood plasma.

[Novel mutation of the GPIIIa gene in the Russian population, Leu40Arg, linked to the Leu33Pro].

Glycoprotein IIb/IIIa complex, a platelet surface fibrinogen receptor, plays a key role in producing primary hemostasis. At present, only a single mutation in the GPIIla gene, Leu33Pro, and a single mutation in the GPIIb gene, lle843Ser, has been described. The mutations are known to enhance signaling functions of the receptor and are associated with the development of arterial thromboses. In the present study, we describe a novel GPIIIa mutation, which is T to G nucleotide substitution in position 1585, resulting in the replacement of Leu for Arg in position 40 of the amino acid sequence of the protein.

[Clinical value of allele variants of cytochrome CYP2C9 gene for anticoagulation therapy with warfarin].

Warfarin is metabolized by cytochrome CYP2C9 and its pharmacokinetic properties depend on structural polymorphisms of CYP2C9 gene. We studied frequencies of allele variants of CYP2C9 gene and associations of individual reaction to warfarin intake with genotype of CYP2C9 gene. Population frequencies of CYP2C9x1, CYP2C9x2, CYP2C9x3 alleles of CYP2C9 gene in St-Petersburg were 82.66, 11.11, and 6.32%, respectively. Carriers of CYP2C9x2 and CYP2C9x3 alleles more rapidly achieved therapeutic levels of hypocoagulation and required significantly lower weekly doses of warfarin.

[The molecular mechanisms of platelets activation in patients with cerebrovascular disease].

Cerebrovascular disease is a main cause of mortality and one of the big medical problems. After the vascular wall's damage the endothelial cells secrete the von Willebrand factor which then connects with its platelet's receptor GP Ib-V-IX. There are two polymorphisms Thr145Met and T(-5)C of the GP Iba gene associated with arterial thrombosis development. Also the difference in platelets' genes expressions was shown in patients with various clinical course of ischemic heart disease. The aim of this study was to investigate the role of platelet's receptor for von Willebrand factor in platelets' activation in patients with cerebrovascular disease. 123 patients with cerebrovascular disease and 97 healthy donors were included into the study. We analyzed the level of receptor for von Willebrand factor on platelet's membrane by flow cytometry, Thr145Met and T(-5)C GP Iba polymorphiams by PCR-RFLP, the GP Iba gene expression by RT-PCR and ADP-induced platelet aggregation by Born method. We have shown: 1) the 145Met GP Iba allele prevalence in patients with atherotrombotic stroke development due to macroangiopathy; 2) the pre-mRNA transform into the mature mRNA in activated platelets and this process may be stopped by the antiplatelet therapy by acetylsalicylic acid.

[Changes in hemostasis system in patients with hereditary thrombophilia caused by mutation of blood coagulation factor V ( factor V Leiden)]. / Izmeneniia v sisteme gemostaza u bol'nykh s nasledstvennoi trombofiliei, obuslovlennoi mutatsiei faktora V svertyvaniia krovi (faktor V Leiden).

AIM: To study the incidence of mutation of Leyden's factor V in patients with venous thrombosis and the hemostatic system in carrier of this genetic defect. MATERIALS AND METHODS: A hundred and one patients aged 15-69 years who had venous thrombosis and 10 individuals with mutation of Leyden's factor V without manifestations in the history of thrombosis were examined. Factor V gene mutations and the thrombocyte and plasma links of hemostasis were determined by routine methods. RESULTS: The Leyden's factor V genotype Arg506-->Gln was detected in 17 of the 101 patients with venous thrombosis. Patients and asymptomatic individuals with this factor were found to have significant hypercoagulation, as evidenced by lower activated protein C-resistance index, higher factor VIII (von Willebrand's factor) activity, elevated von Willebrand's factor antigen levels, and enhanced intravascular platelet activation. In the presence of lupoid anticoagulant, hypercoagulation increased and protein C activity decreased. CONCLUSION: Detection of signs of hypercoagulation in patients with inherited thrombophilia at recovery in carriers of Leyden's factor V without clinical manifestations of thrombosis shows it necessary to make a particularly careful monitoring of the hemostatic system in these subjects. This is especially important for hypercoagulation-predisposing situations, such as pregnancy, surgical interventions, long-term immobilization, use of contraceptives, etc. when preventive measures may be used to prevent thrombotic events.

[Models of inter-group difference of the homeostasis system in patients with artificial heart valves and the set of laboratory parameters]. / Modeli mazhgruppovykh razlichii sostoianiia sitemy gemostaza u bol'nykh s isskustvennymi klapanami serdtsa po kopleksu laboratornykh pokazatelei.

Patients with artificial heart valves (AHV) belong to a unique multi-component model of the homeostasis system presenting an interaction of activated coagulation processes and pharmacological effects, on the one hand, and genetic peculiarities functioning homeostatic mechanisms, on the other hand. The described method was evaluated on the basis of multi-factor mathematic analysis by information-metry. The data obtained provided for isolating the most information-dense laboratory indices and some genetic polymorphisms describing the shaping of continuous intravascular coagulation of stage III in AHV patients. The clinicians and laboratory experts are offered a practical instrument for the diagnosis (prognostication) of the above condition. It was proven as necessary to examine (by the morphofunctional method) the intravascular activation of platelets and to determine the D-dimer in the remote period after prosthesis of heart valves.

[The influence of hereditary thrombophilic mechanisms on the degree of permanent intravascular coagulation in patients with artificial heart valves]. / Vliianie nasledstvennykh trombofilicheskikh mekhanizmov na stepen' postoiannogo vnutrisosudistogo svertyvaniia u bol'nykh s iskusstvennymi klapanami serdtsa.

The genotyping of 40 patients with artificial heart valves (AHV) was performed after prosthesis of the mitral and aotic valves with bicuspid AHV (Medinzh-2 and CarboMedics). The patients took phenylin and varfarin. The patients' genotype was estimated by the thrombophylic genes: factor V Leiden (FVL), prothrombin G20210A, methylene tetrahydrofolate reductase C677T, G/A--455FGB, 4G/5G PAI-1, PI A1/A2 GPIIIa. The genes determining the thrombocytic activity or the vascular wall state substantially influence the third degree of the intensity of the permanent intravascular coagulation (PIC-3) independent of the degree of correction of hemostasis of oral anticoagulants. The addition of anti-aggregants to therapy is the only that can normalize functional activity of thrombocytes in patients with AHV having such defects. The laboratory detection of the genetic defects is of great practical importance for the determination of risk groups of formation of PIC-3 and the strategy of antithrombotic protection of patients with AHV.

[Mean platelet volume: interactions with platelet aggregation activity and glycoprotein IIb-IIIa and Ib expression levels].

Increased mean platelet volume (MPV) is an independent risk factor of thrombotic events in patients with cardiovascular diseases. Interactions of MPV with platelet aggregation activity and contents of glycoprotein (GP) IIb-IIIa (alphaIIb/beta3 integrin, fibrinogen receptor) and GP Ib (von Willebrand factor receptor) were investigated in this study. Investigation was performed in a group of healthy volunteers (n = 38) and in a group of patients with acute coronary syndrome (ACS). In patients blood was collected at days 1, 3-5 and 8-12 after ACS development. As an antiaggregant therapy all patients received acetylsalicylic acid (ASA, inhibitor of thromboxane A2 synthesis) and most of them--clopidogrel (ADP receptor antagonist) with the exception of part of the patients (n = 44) at day 1 who had not taken clopidogrel before first blood collection. In volunteers platelet aggregation was stimulated by 1.25, 2.5, 5 and 20 M ADP, and in patients--by 5 and 20 M ADP. GP IIb-IIIa and GP Ib content on platelet surface was measured using 125I-labelled monoclonal antibodies. GP IIb-IIIa and GP Ib genetic polymorphisms were determined in ACS patients. In healthy donors significant correlations between MPV and aggregation levels were revealed at 1.25 and 2.5 M ADP (coefficients of correlation (r)--0.396 and 0.373, p < 0.05) and at 5 and 20 those interactions did not reach significant level (r--0.279 and 0.205, p > 0.05). Correlations between MPV and aggregation levels were observed at day 1 of ACS in a subgroup of patients who received ASA but had not started clopidogrel treatment (r--0.526, p < 0.01 and 0.368, p < 0.05 for 5 and 20 M ADP respectively). Interactions between these parameters were not registered upon combined treatment with ASA and clopidogrel. Strong direct correlations between MPV and GP IIb-IIIa and GP Ib contents were detected in healthy donors and ACS patients (at all time points) -r from 0.439 to 0.647 (p < or = 0.001 for all correlations). Genetic polymorphisms of GP IIb-IIIa (GP IIIa Leu33Pro) and GP Ib ((-5)T/C (Kozak) and Thr145Met) identified in ACS patients did not affect expression levels of corresponding glycoproteins. The data obtained indicated that increased MPV values correlate with increased platelet aggregation activity and enhanced GP IIb-IIIa and GP Ib expression.

[Variations in glycoprotein IIb-IIIa (alphaIIb/beta3-integrin) content in healthy donors. Influence on platelet aggregation activity and efficacy of aspirin action].

Effects of fibrinogen receptor, glycoprotein (GP) IIb-IIIa (alphaII/(beta3-integrin) content, GP IIIa genetic polymorphism (substitution Leu33Pro) and fibrinogen concentration in blood plasma on platelet aggregation activity were studied in a group of healthy volunteers. The GP IIb-IIIa content on platelet surface in 35 tested donors varied (40-71) x 10(3) per platelet. Repeated measurements revealed that the GP IIb-IIIa content coefficient of variation was 9.5%, and deviations from mean levels did not exceed 20%. The level and rate of platelet aggregation induced by ADP (1.25-20 M) correlated with GP IIb-IIIa number (r from 0.315 to 0.591) and were higher in a group of donors with high in comparison with low GP IIb-IIIa content (> 60 and (40-50) x 10(3) per platelet respectively). Aspirin, the inhibitor of thromboxane A2 synthesis, partially suppressed ADP-induced platelet aggregation. The level of residual aggregation in the presence of aspirin also correlated with GP IIb-IIIa content and increased in subjects with high receptor content. Parameters of ADP-induced aggregation did not differ in donors with GP IIIa Pro33(-) (Leu33Leu33, n = 20) and Pro33(+) (Leu33Pro33, n = 13, and Pro33Pro33, n = 2) genotype. GP IIb-IIIa content was also not affected by GP IIIa polymorphism. No significant correlations were found between the level and rate of platelet aggregation and fibrinogen concentration in blood plasma. The data obtained indicate that effects of GP IIb-IIIa variations in content on platelet aggregation are higher than GP IIIa Leu33Pro polymorphism and variations of fibrinogen concentration. High GP IIb-IIIa content is associated with increased platelet aggregation activity and decreased efficacy of aggregation inhibition by aspirin.

Participation of IIb-IIIa glycoprotein in spontaneous platelet aggregation.

In some patients with stable and unstable angina pectoris and in some donors without clinical manifestations of cardiovascular diseases and other pathologies, spontaneous platelet aggregation was completely suppressed by glycoprotein IIb-IIIa antagonists blocking the interaction of this glycoprotein with fibrinogen. Antibodies inhibiting binding of glycoprotein Ib with von Willebrand factor had no effect on the level and rate of spontaneous platelet aggregation. In the donor group, the level of spontaneous aggregation was almost 1.5-fold higher in persons with a certain genetic polymorphism (Leu-->Pro substitution in position 33 of glycoprotein IIIa). The level of spontaneous aggregation correlated with the amount of glycoprotein IIb-IIIa on the platelet surface (r = 0.41).