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1.
Ter Arkh ; 90(7): 4-13, 2018 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-30701917

RESUMO

Laboratory methods used for the diagnostics of thrombocytopenias are reviewed. Differential diagnosis is usually carried out between immune and hypoproductive forms of thrombocytopenia. Immune thrombocytopenias are caused by appearance in blood of antiplatelet abtibodies and accelerated destruction of platelets sensibilized by those antibodies, and hypoproductive thrombocytopenias - by impaired platelet production in the bone marrow. Main directions of the laboratory diagnostics of thrombocytopenias - analysis of auto- and alloautoantibodies and evaluation of platelet production and turnover in the blood stream. The following methods are used for the investigation of antiplatelet antibodies: 1) measurement of platelet associated immunoglobulins; 2) determination of circulating antibodies reacting with platelets; 3) determination of antibodies using antigen specific methods - by their reactivity with isolated platelet antigens (glycoproteins). Efficacy of platelet production could be assessed by measuring in blood the amount of "young" (reticulated) platelets. One more method for the evaluation of platelet production as well as the rate of platelet turnover - measurement of plasma soluble glycocalicin, glycoprotein Ib fragment shed from the surface of platelets upon their destruction in spleen and liver. In patients with immune thrombocytopenia autoantibodies are evaluated in all cases, the percentage of reticulated platelets is significantly increased and the amount of plasma glycocalicin is within the normal range or increased. In patients with hypoproductive thrombocytopenia autoantibodies are not detected or detected at low level, the percentage of reticulated platelets is within the normal range or slightly increased and the amount of plasma glycocalicin is lowered. Diagnostics of hapten forms of immune thromocytopenias (heparin-induced thrombocytopenia and others) and of alloimmune thrombocytopenias (neonatal alloimmune thrombocytopenia in particular) are considered in the separate sections of this review.


Assuntos
Plaquetas , Trombocitopenia/sangue , Antígenos de Plaquetas Humanas/sangue , Antígenos de Plaquetas Humanas/imunologia , Autoanticorpos/sangue , Plaquetas/citologia , Plaquetas/imunologia , Diagnóstico Diferencial , Humanos , Contagem de Plaquetas , Púrpura Trombocitopênica Idiopática/sangue
2.
Ter Arkh ; 90(7): 65-69, 2018 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-30701924

RESUMO

AIM: Mechanisms underlying the development of neonatal alloimmune thrombocytopenia (NAIT) in in Russia have been studied. MATERIALS AND METHODS: Genetic polymorphisms of human platelet alloantigens (HPA) -1, -2, -3, -4, -5, and -15 were evaluated in 27 families having the newborns with NAIT. NAIT was diagnosed according to the following criteria: (1) newborn with thrombocytopenia; (2) mother with no thrombocytopenia and no increase of platelet associated IgG, (3) presence of antibodies reacting with paternal platelets in maternal plasma / serum. HPA genotyping revealed incompatibilities in 23 out of 27 tested families. In these 23 families HPA-1 conflicts were detected in 16 ones (70%). In 8 cases mothers were homozygous carriers of rare HPA-1b allele and in another 8 cases - of HPA-1a allele which cased incompatibilities with fetal HPA-1a and HPA-1b respectively. In 5 out of 23 families (22%) there were incompatibilities with fetal HPA-15 (HPA-15a, n=2 and HPA-15b, n=3), in 1 family - with HPA-5b (4%), and in 1 family - with HPA-3b (4%) alloantigens. CONCLUSION: In conclusion the main causes of NAIT in Russia were HPA-1a and -1b conflicts and HPA-15 conflicts were the second frequent ones.


Assuntos
Antígenos CD/sangue , Antígenos de Plaquetas Humanas/sangue , Incompatibilidade de Grupos Sanguíneos/imunologia , Plaquetas/imunologia , Proteínas de Neoplasias/sangue , Polimorfismo Genético , Trombocitopenia Neonatal Aloimune/imunologia , Alelos , Antígenos CD/genética , Antígenos de Plaquetas Humanas/genética , Autoanticorpos/sangue , Incompatibilidade de Grupos Sanguíneos/genética , Tipagem e Reações Cruzadas Sanguíneas , Feminino , Proteínas Ligadas por GPI/sangue , Proteínas Ligadas por GPI/genética , Genótipo , Humanos , Imunoglobulina G/sangue , Recém-Nascido , Integrina beta3 , Proteínas de Neoplasias/genética , Gravidez , Trombocitopenia Neonatal Aloimune/sangue , Trombocitopenia Neonatal Aloimune/genética
3.
Dokl Biochem Biophys ; 470(1): 322-325, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27817018

RESUMO

Size of membrane microparticles (MPs) from blood plasma and MPs produced in vitro by activated endothelial cells (ECs), monocytes, THP-1 monocytic cells, granulocytes, and platelets was evaluated by dynamic light scattering. MPs were sedimented from the culture media, cell supernatants, and plasma at 20 000 g for 30 min. Average diameters of all types of MPs ranged from 300 to 600 nm. Plasma MPs had the smallest size. Close sizes were registered for MPs from platelets and THP-1 cells. MPs from monocytes were larger, and MPs from granulocytes and ECs were the largest ones. The data obtained indicate that the size of membrane MPs depends on the type of their cell-producers.


Assuntos
Plaquetas , Micropartículas Derivadas de Células , Difusão Dinâmica da Luz , Células Endoteliais , Granulócitos , Monócitos , Análise de Variância , Plaquetas/metabolismo , Linhagem Celular , Micropartículas Derivadas de Células/metabolismo , Meios de Cultura , Células Endoteliais/metabolismo , Granulócitos/metabolismo , Humanos , Monócitos/metabolismo , Tamanho da Partícula , Veias Umbilicais/citologia , Veias Umbilicais/metabolismo
4.
Biochemistry (Mosc) ; 81(2): 114-21, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27260391

RESUMO

Activity of tissue factor (TF) in membrane microparticles (MPs) produced in vitro by endothelial cells (ECs), monocytes, THP-1 monocytic cells, granulocytes, and platelets was investigated. ECs were isolated from human umbilical vein, and monocytes, granulocytes, and platelets - from the blood of healthy donors. ECs, monocytes, and THP-1 cells were activated by bacterial lipopolysaccharide, granulocytes - by lipopolysaccharide or phorbol myristate acetate, and platelets - by SFLLRN, thrombin receptor-activating peptide. MPs were sedimented from the culture medium or supernatant of activated cells at 20,000g for 30 min. Coagulation activity of MPs was analyzed in a modified recalcification assay by assessing their effects on coagulation of donor plasma depleted of endogenous MPs (by centrifuging at 20,000g for 90 min). MPs from all cell types accelerated plasma coagulation. Antibodies blocking TF activity prolonged coagulation lag-phase in the presence of MPs from ECs, monocytes, and THP-1 cells (by 2.7-, 2.0-, and 1.8-fold, respectively), but did not influence coagulation in the presence of MPs from granulocytes and platelets. In accordance with these data, TF activity measured by its ability to activate factor X was found in MPs from ECs, monocytes, and THP-1 cells, but not in MPs from granulocytes and platelets. The data obtained indicate that active TF is present in MPs produced in vitro by ECs, monocytes, and THP-1 cells, but not in MPs derived from granulocytes and platelets.


Assuntos
Células Sanguíneas/química , Micropartículas Derivadas de Células/química , Células Endoteliais/química , Tromboplastina/metabolismo , Células Sanguíneas/citologia , Células Sanguíneas/metabolismo , Linhagem Celular , Micropartículas Derivadas de Células/metabolismo , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Humanos , Tromboplastina/análise
5.
Dokl Biochem Biophys ; 471(1): 431-434, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28058691

RESUMO

Platelets bearing leukocyte antigen CD45 were identified in the blood of patients with myocardial infarction (MI) and healthy donors by flow cytofluorimetry. Part of these platelets contained tissue factor (TF)-primary initiator of blood clotting. The number of CD45+ and CD45+/TF+ platelets in MI patients at the first day was comparable with their level in healthy donors, but was increased at 8-12 days after MI onset. At that time in some patients the amount of CD45+ and CD45+/TF+ platelets reached 5-6 and 2-3% of their total number. It is assumed that CD45+/TF+ platelets could be formed as a result of platelet interaction with leukocytes or leukocyte produced membrane microparticles.


Assuntos
Plaquetas/metabolismo , Antígenos Comuns de Leucócito/sangue , Infarto do Miocárdio/sangue , Tromboplastina/metabolismo , Micropartículas Derivadas de Células/metabolismo , Progressão da Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Tempo
6.
Ter Arkh ; 86(9): 83-9, 2014.
Artigo em Russo | MEDLINE | ID: mdl-25518511

RESUMO

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.


Assuntos
Síndrome Coronariana Aguda , Aspirina , Citocromo P-450 CYP2C19/genética , Agregação Plaquetária/efeitos dos fármacos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/genética , Ticlopidina/análogos & derivados , Síndrome Coronariana Aguda/sangue , Síndrome Coronariana Aguda/tratamento farmacológico , Síndrome Coronariana Aguda/genética , Aspirina/administração & dosagem , Aspirina/farmacocinética , Testes de Coagulação Sanguínea , Clopidogrel , Esquema de Medicação , Monitoramento de Medicamentos , Feminino , Humanos , Masculino , Volume Plaquetário Médio/métodos , Inibidores da Agregação Plaquetária/administração & dosagem , Inibidores da Agregação Plaquetária/farmacocinética , Estatística como Assunto , Ticlopidina/administração & dosagem , Ticlopidina/farmacocinética , Fatores de Tempo
7.
Biomed Khim ; 60(1): 94-108, 2014.
Artigo em Russo | MEDLINE | ID: mdl-24749250

RESUMO

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.


Assuntos
Síndrome Coronariana Aguda/genética , Plaquetas/metabolismo , Expressão Gênica , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/genética , Complexo Glicoproteico GPIb-IX de Plaquetas/genética , Trombose/genética , Síndrome Coronariana Aguda/complicações , Síndrome Coronariana Aguda/tratamento farmacológico , Síndrome Coronariana Aguda/patologia , Difosfato de Adenosina/farmacologia , Aspirina/uso terapêutico , Plaquetas/efeitos dos fármacos , Plaquetas/patologia , Estudos de Casos e Controles , Clopidogrel , Feminino , Humanos , Masculino , Volume Plaquetário Médio , Pessoa de Meia-Idade , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/uso terapêutico , Polimorfismo Genético , Prognóstico , Fatores de Risco , Trombose/complicações , Trombose/tratamento farmacológico , Trombose/patologia , Ticlopidina/análogos & derivados , Ticlopidina/uso terapêutico
8.
Bull Exp Biol Med ; 155(1): 89-91, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23667880

RESUMO

Spontaneous platelet aggregation was evaluated in patients with acute coronary syndrome on days 1, 3-5, and 8-12 of the disease. On day 1, aggregation was analyzed after aspirin, but before clopidogrel administration; during other periods after both antiaggregants. The mean levels of spontaneous aggregation after antithrombotic therapy did not change during different periods after the onset of acute coronary syndrome, in contrast to ADP-induced aggregation that decreased after the development of clopidogrel effects (days 3-5 and 8-12). Spontaneous aggregation during different periods directly correlated (r>0.4, p<0.01) with spontaneous and ADP-induced aggregation during different periods (r=0.372, r=0.447, and r=0.543 on days 1, 3-5, and 8-12, respectively; p<0.01). No relationship between spontaneous aggregation and plasma concentration of von Willebrand's factor was detected. Spontaneous aggregation was completely suppressed after in vitro addition of prostaglandin E1 (platelet activation inhibitor), slightly (by ≈20%) decreased in the presence of antibodies to glycoprotein Ib, blocking its reactions with von Willebrand's factor, and did not change in the presence of aptamer inhibiting thrombin activity.


Assuntos
Síndrome Coronariana Aguda/sangue , Síndrome Coronariana Aguda/tratamento farmacológico , Aspirina/uso terapêutico , Inibidores da Agregação Plaquetária/uso terapêutico , Agregação Plaquetária/efeitos dos fármacos , Ticlopidina/análogos & derivados , Alprostadil/farmacologia , Anticorpos/imunologia , Plaquetas/efeitos dos fármacos , Clopidogrel , Humanos , Ativação Plaquetária/efeitos dos fármacos , Adesividade Plaquetária/efeitos dos fármacos , Complexo Glicoproteico GPIb-IX de Plaquetas/imunologia , Ticlopidina/uso terapêutico , Fator de von Willebrand/metabolismo
9.
Kardiologiia ; 51(7): 4-7, 2011.
Artigo em Russo | MEDLINE | ID: mdl-21878077

RESUMO

Interaction between aggregating activity of platelets and glycoprotein (GP) IIb/IIIa (fibrinogen receptor) content on their surface was investigated in patients with acute coronary syndrome (ACS). Eighty nine ACS patients were included into the study - 69 with and 20 without elevation of ST segment. Blood was collected within the first hour of admission to the clinic (1 day), and then at 3-5 and 8-12 days. All patients received standard antiaggregant therapy - acetylsalicylic acid - ASA (thromboxane A2 synthesis inhibitor) and clopidogrel (ADP receptor antagonist). Platelet aggregation was analyzed at the first time point when patients had already taken ASA but not clopidogrel, and then (3-5 and 8- 12 days) upon combined therapy with both preparations. Aggregation was induced by 5 and 20 uM ADP and measured by turbidimetric method. In comparison with the initial level (1 day, ASA) at days 3-5, i.e. after development of clopidogrel effect, platelet aggregation was decreased by 54 and 40% upon its stimulation with 5 and 20 uM ADP, and was not further changed at days 8-12. GP IIb/IIIa content on platelet surface was determined by binding of 125I-labelled monoclonal antibody CRC64. GP IIb/IIIa number varied from 31100 to 73000 per platelet with the mean level of 48500 +/- 8400 (mean +/- standard deviation). No differences were detected between mean GP IIb/IIIa number at 1, 3-5 and 8-12 days after ACS onset. Upon repeat GP IIb/IIIa measurement coefficient of variation was 6.1% demonstrating the stability of this parameter in each patient. Positive correlation between platelet aggregation and GP IIb/IIIa content was detected at the first day - correlation coefficients (r) 0.425 and 0.470 for 5 and 20 uM ADP (n=57, p<0.001). However positive association between these parameters was not revealed at 3-5 and 8-12 days, when patients received not only ASA but clopidogrel as well (r from -0.054 to -0.237, p>0.05). These results indicates that variations of GP IIb/IIIa content affect platelet aggregating activity within first hours of ACS upon ASA treatment. However after saturation with clopidogrel this factor has no significant influence on platelet aggregation, at least on aggregation induced by ADP which receptor is the target of this antiaggregant. Under such conditions aggregation parameters are presumably influenced first of all by individual characteristics of clopidogrel pharmacokinetics.


Assuntos
Síndrome Coronariana Aguda/tratamento farmacológico , Aspirina/farmacocinética , Plaquetas , Agregação Plaquetária/efeitos dos fármacos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Ticlopidina/análogos & derivados , Síndrome Coronariana Aguda/diagnóstico , Síndrome Coronariana Aguda/metabolismo , Aspirina/administração & dosagem , Plaquetas/efeitos dos fármacos , Plaquetas/metabolismo , Clopidogrel , Esquema de Medicação , Cálculos da Dosagem de Medicamento , Eletrocardiografia , Feminino , Humanos , Masculino , Nefelometria e Turbidimetria , Inibidores da Agregação Plaquetária/administração & dosagem , Inibidores da Agregação Plaquetária/farmacocinética , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/análise , Ticlopidina/administração & dosagem , Ticlopidina/farmacocinética , Fatores de Tempo
10.
Platelets ; 22(4): 243-51, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21329420

RESUMO

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.


Assuntos
Síndrome Coronariana Aguda/metabolismo , Plaquetas/metabolismo , Agregação Plaquetária/fisiologia , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Síndrome Coronariana Aguda/genética , Fibrinogênio/metabolismo , Humanos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/genética , Complexo Glicoproteico GPIb-IX de Plaquetas/metabolismo , Polimorfismo Genético/genética
11.
Bull Exp Biol Med ; 150(4): 422-5, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22268033

RESUMO

Characteristics of a new antithrombin DNA-aptamer RE31 were studied. This aptamer inhibited thrombin formation in human plasma catalyzed by exogenous (lengthening of thrombin time) and endogenous thrombin (lengthening of partial prothrombin time and activated partial thromboplastin time). In addition, the aptamer completely suppressed thrombin-induced aggregation of human platelets. On the other hand, RE31 did not reduce amidolytic activity of thrombin towards the short peptide substrate, in other words, did not modify the state of enzyme active center. By the capacity to inhibit clotting reactions, RE31 was superior to the previously described highly effective 31-component antithrombin aptamer 31TBA (thrombin binding aptamer, TBA). The effect of RE31 was species-specific: it inhibited human thrombin activity more effectively than activities of rat and rabbit thrombins.


Assuntos
Antitrombinas/farmacologia , Aptâmeros de Nucleotídeos/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Trombina/antagonistas & inibidores , Animais , Coagulação Sanguínea/efeitos dos fármacos , Coagulação Sanguínea/fisiologia , Humanos , Inibidores da Agregação Plaquetária/farmacologia , Coelhos , Ratos , Trombina/metabolismo
12.
Bull Exp Biol Med ; 148(1): 33-6, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19902090

RESUMO

The effects of two DNA aptamers (oligonucleotides) 15TBA and 31TBA (15- and 31-mer thrombin-binding aptamers, respectively) on thrombin activity were studied. Both aptamers added to human plasma dose-dependently increased thrombin time (fibrin formation upon exposure to exogenous thrombin), prothrombin time (clotting activation by the extrinsic pathway), and activated partial thromboplastin time (clotting activation by the intrinsic pathway). At the same time, these aptamers did not modify amidolytic activity of thrombin evaluated by cleavage of synthetic chromogenic substrate. Aptamers also inhibited thrombin-induced human platelet aggregation. The inhibitory effects of 31TBA manifested at lower concentrations than those of 15TBA in all tests. These data indicate that the studied antithrombin DNA aptamers effectively suppress its two key reactions, fibrin formation and stimulation of platelet aggregation, without modifying active center of the thrombin molecule.


Assuntos
Antitrombinas/farmacologia , Aptâmeros de Nucleotídeos/farmacologia , Aptâmeros de Nucleotídeos/química , Sequência de Bases , Relação Dose-Resposta a Droga , Humanos
13.
Biomed Khim ; 54(3): 361-71, 2008.
Artigo em Russo | MEDLINE | ID: mdl-18712091

RESUMO

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.


Assuntos
Aspirina/farmacologia , Inibidores da Agregação Plaquetária/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/genética , Plaquetas/efeitos dos fármacos , Plaquetas/metabolismo , Fibrinogênio/metabolismo , Humanos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Polimorfismo Genético , Valores de Referência
14.
Kardiologiia ; 47(6): 4-9, 2007.
Artigo em Russo | MEDLINE | ID: mdl-18260867

RESUMO

Soluble P-selectin (marker of activation of platelets) and von Willebrand factor (marker of activation of endothelium) were measured in 44 patients with non ST-Elevation acute coronary syndrome (NSTEACS) 21 of whom received glycoprotein IIb/IIIa antagonist eptifibatide (two 180 mg/kg boluses with 10 min interval followed by infusion of 2 mcg/kg/min during first 24 hours and 1.3 mcg/kg/min during subsequent 48 hours). Measurements were made within first 2 hours, in 2--3 and 10--14 days after development of NSTEACS. During first 2 hours P-selectin content was 1.6 times higher than in healthy donors, but in 2--3 and 10--14 days after onset of NSTEACS it did not differ from normal values. Contrary to P-selectin value of von Willebrand factor was elevated both during first 2 hours (1.3 times) and in 2--3 days (2 times) compared with healthy donors. Some elevation of von Willebrand factor (1.2 times) persisted after 10--14 days after development of NSTEACS. The results obtained have shownd that elevated activity of endothelium persists at least for 2--3 days after onset of NSTEACS, while activity of platelets during this period decreases. In none of temporal points there have been revealed differences in contents of P-selectin and von Willebrand factor between groups of patients receiving and not receiving glycoprotein IIb/IIIa antagonists. No differences were also found between these parameters in groups of patients favorable and unfavorable outcomes (myocardial infarction, angina recurrence) of the disease during 30 days of follow-up.


Assuntos
Síndrome Coronariana Aguda/sangue , Eletrocardiografia , Selectina-P/sangue , Peptídeos/uso terapêutico , Inibidores da Agregação Plaquetária/uso terapêutico , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/antagonistas & inibidores , Fator de von Willebrand/metabolismo , Síndrome Coronariana Aguda/tratamento farmacológico , Síndrome Coronariana Aguda/fisiopatologia , Relação Dose-Resposta a Droga , Endotélio Vascular/metabolismo , Eptifibatida , Seguimentos , Humanos , Técnicas Imunoenzimáticas , Infusões Intravenosas , Peptídeos/administração & dosagem , Inibidores da Agregação Plaquetária/administração & dosagem , Resultado do Tratamento
15.
Bull Exp Biol Med ; 143(4): 422-5, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18214290

RESUMO

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).


Assuntos
Plaquetas/metabolismo , Agregação Plaquetária/fisiologia , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Anticorpos Monoclonais/farmacologia , Anticorpos Monoclonais/uso terapêutico , Aspirina/farmacologia , Aspirina/uso terapêutico , Plaquetas/efeitos dos fármacos , Doenças Cardiovasculares/sangue , Doenças Cardiovasculares/tratamento farmacológico , Fibrinogênio/metabolismo , Humanos , Mutação , Fragmentos de Peptídeos/farmacologia , Fragmentos de Peptídeos/uso terapêutico , Agregação Plaquetária/efeitos dos fármacos , Agregação Plaquetária/genética , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/antagonistas & inibidores , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/genética , Polimorfismo Genético , Ligação Proteica/efeitos dos fármacos , Fator de von Willebrand/metabolismo
16.
Platelets ; 13(8): 465-77, 2002 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12487780

RESUMO

The purpose of the study was to evaluate safety, effects on platelet aggregation and pharmacokinetics of F(ab')(2) fragments of anti-glycoprotein (GP) IIb-IIIa murine monoclonal antibody FRaMon (F(ab')(2) FRaMon) upon its intravenous administration in patients undergoing high-risk coronary angioplasty. Patients were treated before angioplasty with F(ab')(2) FRaMon at 0.2 mg/kg (n = 17) and 0.25 mg/kg (n = 12) bolus or with abciximab at 0.25 mg/kg bolus + 12 h infusion at 0.125 microg/kg per min (n = 29). F(ab')(2) FRaMon at both doses decreased platelet aggregation induced by 20 microM ADP to <10, <20, <40 and <70% of the predrug level at 1, 12, 24 and 72 h after injection, respectively. No significant differences were observed between F(ab')(2) FRaMon and abciximab antiaggregatory effects. In none of the patients did F(ab')(2) FRaMon cause allergic reactions, major bleedings or deep thrombocytopenia. Antibodies against F(ab')(2) FRaMon were detected in one patient. Free F(ab')(2) FRaMon was cleared from plasma within 12 h, while platelet-bound preparation occupied >95, 70-80 and 40-50% of GP IIb-IIIa at 1 and 12-24 h and 3 days after injection, respectively. Thrombotic complications within the first month after angioplasty in groups treated with F(ab')(2) FRaMon and abciximab were observed in one and two patients, respectively. The data obtained have shown that F(ab')(2) FRaMon at bolus administration to patients undergoing coronary angioplasty caused no serious side effects and at comparative dosage inhibited platelet aggregation with the same efficacy as abciximab at bolus + infusion administration.


Assuntos
Angioplastia Coronária com Balão/efeitos adversos , Anticorpos Monoclonais/uso terapêutico , Fragmentos Fab das Imunoglobulinas/uso terapêutico , Inibidores da Agregação Plaquetária/farmacologia , Inibidores da Agregação Plaquetária/uso terapêutico , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Abciximab , Animais , Anticorpos/sangue , Anticorpos Monoclonais/efeitos adversos , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Fragmentos Fab das Imunoglobulinas/efeitos adversos , Fragmentos Fab das Imunoglobulinas/metabolismo , Masculino , Camundongos , Pessoa de Meia-Idade , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/farmacocinética , Contagem de Plaquetas , Reoperação , Medição de Risco , Segurança
17.
Kardiologiia ; 42(6): 8-17, 2002.
Artigo em Russo | MEDLINE | ID: mdl-12494124

RESUMO

Preparation framon [F(ab')2 fragments of the anti-glycoprotein (GP) IIb/IIIa monoclonal antibody (FRaMon)] blocks fibrinogen binding to GP IIb/IIIa and platelet aggregation. Dynamics of platelet aggregation inhibition, safety, and clinical effects of framon were studied in high-risk coronary angioplasty. Twenty seven patients underwent angioplasty with framon, 29 - with abciximab and 28 - with no GP IIb/IIIa antagonists. Framon at 0.2 mg/kg (n=16) and 0.25 mg/kg (n=11) bolus administration inhibited platelet aggregation induced by 20 mcM ADP by more than 90%, 80%, 60% and 30% in comparison with the predrug level 1, 12, 24 and 72 h after injection, respectively. Almost the same dynamics of aggregation inhibition was observed upon abciximab administration at 0.25 mg/kg bolus + 0.125 mcg/kg/min infusion for 12 h. No signs of individual intolerance and side effects including allergic reactions and bleedings were detected in patients treated with framon. Slight decrease of platelet count (15-20%) was observed on the first day after framon administration. Antibodies against framon were detected in 1 out of 22 tested patients. Free (nonbound to platelets) framon was completely removed from the circulation 12 h after injection. The number of endpoints (death, myocardial infarction and indications for repeat revascularization) within 1 year after angioplasty was approximately the same in the groups with framon and abciximab - 7 of 25 (28%) and 7 of 28 (25%), respectively, and more than 1.5 fold higher in the group without GP IIb/IIIa blockers - 12 of 27 (44,4%).


Assuntos
Angioplastia Coronária com Balão/métodos , Fragmentos Fab das Imunoglobulinas/farmacologia , Fragmentos Fab das Imunoglobulinas/uso terapêutico , Integrina beta3/efeitos dos fármacos , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/cirurgia , Inibidores da Agregação Plaquetária/farmacologia , Inibidores da Agregação Plaquetária/uso terapêutico , Glicoproteína IIb da Membrana de Plaquetas/efeitos dos fármacos , Terapia Combinada , Feminino , Fibrinogênio/efeitos dos fármacos , Humanos , Fragmentos Fab das Imunoglobulinas/efeitos adversos , Masculino , Pessoa de Meia-Idade , Inibidores da Agregação Plaquetária/efeitos adversos , Receptores Imunológicos/uso terapêutico , Fatores de Risco
18.
Ter Arkh ; 73(9): 66-73, 2001.
Artigo em Russo | MEDLINE | ID: mdl-11642086

RESUMO

AIM: To study the effects of F(ab')2 fragments of the monoclonal antibody (monAB) FRaMon against glycoproteins (GP) IIb-IIIa on platelet aggregating activity in vitro and after injection to healthy volunteers. MATERIAL AND METHODS: In vitro experiments were performed to study effects of F(ab')2 and Fab fragments of FRaMon on platelet aggregation (PA) and 14C-serotonin secretion and characteristics of 125I-labelled F(ab')2 and Fab FRaMon binding to platelets. In vivo effects of F(ab')2 FRaMon (preparation FRAMON) were studied upon its bolus i.v. injection to 10 healthy volunteers at the doses of 0.025-0.2 mg/kg. PA was registered before and 1, 6, 12, 24 hours and 3 and 12-15 days after FRAMON injection. FRAMON binding to platelets in the vascular bed was evaluated by inhibition of 125I-FRAMON in vitro binding to platelets obtained from volunteers. Development of antibodies against FRAMON was evaluated by ELISA two weeks after FRAMON injection. RESULTS: In vitro F(ab')2 FRaMon completely blocked PA induced by ADP and thrombin at the concentrations < 4 and < 7.5 mcg/ml, respectively, and revealed higher inhibitory capacity than Fab FRaMon. F(ab')2 FRamon also inhibited 14C-serotonin secretion from ADP-activated platelets. F(ab')2 FRamon interacted with two GP IIb-IIIa molecules on one platelet and bound to platelets more tightly than Fab FRaMon. F(ab')2 FRaMon (preparation FRAMON) bolus i.v. injection to healthy volunteers at the doses of 0.025-0.2 mg/kg did not induce any signs of individual intolerance, including allergic reactions, bleeding and thrombocytopenia. FRAMON at 0.2 mg/kg almost completely inhibited ADP-induced PA of volunteer's platelets 1 h after injection and by more than 70% at 12 h and by more than 50% at 24 h after injection. PA ability recovered to normal 3 days after injection. Antibodies against FRAMON were detected in 1 out of 10 volunteers. CONCLUSION: F(ab')2 fragments of monAB FRaMon effectively inhibited aggregating ability both in vitro and after injection to healthy volunteers and could be suggested as a basis for development of a new GP IIb-IIIa antagonist.


Assuntos
Anticorpos Monoclonais/farmacologia , Fragmentos Fab das Imunoglobulinas/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Animais , Humanos , Técnicas In Vitro , Camundongos
20.
Biochemistry (Mosc) ; 63(6): 710-8, 1998 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-9668212

RESUMO

Effects of two lectins, wheat germ agglutinin (WGA) and concanavalin A (Con A), on platelet functional reactions and interaction of lectins with the platelet membrane glycoproteins (GPs) have been studied. Both lectins stimulated platelet aggregation and secretion of serotonin from platelet dense granules. The effects of WGA and Con A were blocked by specific sugars, N-acetyl-D-glucosamine and alpha-methyl-D-mannopyranoside, respectively, by adenylate cyclase activator prostaglandin E1, and by anti-GP IIb-IIIa monoclonal antibody (monAB), CRC64, that inhibits platelet interaction with fibrinogen. The data indicate that both lectins interacting with the carbohydrate moiety on the platelet surface stimulated not passive agglutination but fibrinogen--GP IIb-IIIa-dependent platelet aggregation which is coupled with the secretion from granules and activation of the intracellular systems of signal transduction. However, there were significant differences between the stimulatory effects of WGA and Con A. WGA induced more pronounced and quick platelet aggregation and stimulated several times higher serotonin secretion than Con A. In addition, adhesion studies showed that plastic-adsorbed WGA appeared to be a nonadhesive substrate, whereas Con A effectively stimulated platelet adhesion. Unlike Con A-induced platelet aggregation, adhesion to Con A substrate was not inhibited by monAB CRC64, i.e., was not dependent on GP IIb-IIIa--fibrinogen interaction. Binding of lectins with major platelet GPs was studied using immobilized WGA and Con A and platelet lysate as a source of GPs. Platelet lysate was incubated with immobilized lectins and then binding of individual GPs was evaluated using specific mono- and polyclonal antibodies. WGA binds with GP Ib and P-selectin but not with other GPs tested. Interaction of Con A with platelet GPs was less specific. This lectin binds with GP IIb-IIIa, GP Ib, GP IV, and P-selectin. Although GP Ib appeared to be the main protein which bound WGA on platelet surface, anti-GP Ib antibodies failed to affect WGA-induced platelet aggregation, but inhibited WGA-induced agglutination of fixed platelets. Thus, interaction of the WGA with GP Ib could not be considered as a major stimulus initiating WGA-dependent platelet activation and aggregation.


Assuntos
Plaquetas/efeitos dos fármacos , Concanavalina A/farmacologia , Ativação Plaquetária/efeitos dos fármacos , Agregação Plaquetária/efeitos dos fármacos , Glicoproteínas da Membrana de Plaquetas/metabolismo , Aglutininas do Germe de Trigo/farmacologia , Plaquetas/citologia , Plaquetas/metabolismo , Adesão Celular/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Humanos , Glicoproteínas da Membrana de Plaquetas/imunologia , Ligação Proteica , Serotonina/metabolismo
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