Jela Ivanková

Variability of GP6 gene in patients with sticky platelet syndrome and deep venous thrombosis and/or pulmonary embolism.

The GP6 gene encodes the GPVI, a crucial platelet membrane glycoprotein, for adequate platelet activation, adhesion and aggregation. The objectives of the present study were to assess the genetic variability of the GP6 gene in patients with platelet hyperaggregability phenotype, known as sticky platelet syndrome (SPS) manifesting as deep vein thrombosis (DVT), and/or pulmonary embolism, and in controls; and to evaluate its role in the pathogenesis of venous thromboembolism (VTE) in SPS. Seventy-seven patients with SPS and 77 healthy blood donors as controls were enrolled. Light transmission aggregometry was used to diagnose SPS according to the method of Mammen and Bick. Seven single-nucleotide polymorphisms (SNPs) of the GP6 gene (rs1654410, rs1671153, rs1654419, rs11669150, rs12610286, rs1654431, rs1613662) were assessed using restriction fragment length polymorphism analysis. A significant association between 1613662-G [P < 0.05, odds ratio (OR) 2.087, confidence interval (CI) 1.049–4.148], 1654419-A (P < 0.05, OR 2.161, CI 1.020–4.577) and VTE was found in patients with SPS. The analysis based on SPS type revealed a significantly higher occurrence of 1671153-G (P < 0.05, OR 2.317, CI 1.103–4.865) and 1654419-A (P < 0.05, OR 2.317, CI 1.103–4.865) in the SPS type II compared to the control group. No association between the studied GP6 genotypes and the severity of VTE (pulmonary embolism vs. DVT) was found. In the patients, significant positive relationship between the 1671153-G, 1654419-A, 1613662-G alleles and male sex was observed. GP6 SNPs 1613662-G, 1671153-G and 1654419-A alleles are associated with an increased risk of VTE in SPS. They could contribute to the SPS phenotype.

Fibronectin, plasminogen activator inhibitor type 1 (PAI-1) and uterine artery Doppler velocimetry as markers of preeclampsia

Objective: The purpose of this study was to examine plasma levels of fibronectin and plasminogen inhibitor type 1 (PAI-1), and alterations in uterine artery (UtA) waveforms throughout normotensive and preeclamptic pregnancies and to analyze its predictive value for the detection of preeclampsia within the second trimester of pregnancy. Material and methods: Blood samples were collected from 102 healthy, nulliparous women between the 24th and 26th gestational week. Preeclampsia developed in 13 patients; 89 normotensive control subjects were matched from the same cohort. Plasma samples were assayed for fibronectin and PAI-1 by enzyme-linked immunosorbent assay. Color pulsed Doppler examinations of UtA were performed after blood sampling. Trends were compared between two groups. Results: Maternal plasma fibronectin and PAI-1 levels and average PI, RI and S/D ratios of patients with preeclampsia were significantly higher (p < 0.05). The best cut-off values for predicting preeclampsia of fibronectin, PAI-1, PI, RI, S/D ratio based on ROC curve analysis were 290 mg/ml, 77.3 ng/ml, 1,0615, 0.605 and 2,59 respectively. The areas under the curve equal to 0.705, 0.753, 0.689, 0.695 and 0.699 for fibronectin, PAI-1 and uterine artery Doppler PI, RI, S/D ratio were determined for the prediction of preeclampsia. Conclusions: Fibronectin, PAI-1 and UtA Doppler are potentially useful predictors of preeclampsia. Maternal plasma PAI-1 combinated with fibronectin had the highest predictive values in our study.

Soluble P-Selectin During a Single Hemodialysis Session in Patients With Chronic Renal Failure and Erythropoietin Treatment:

In several studies, hemodialysis (HD) patients treated with recombinant human erythropoietin (rHuEPO) because of renal anemia showed increased levels of soluble adhesion molecules. The purpose of the study was to investigate the changes of soluble P-selectin (sSELP) and its relationship to platelet activation during a single HD session in patients with long-term rHuEPO treatment. Fifty-two HD patients with chronic renal failure were involved—26 with rHuEPO treatment (EPO group) and 26 without (non-EPO group). Thirty healthy subjects served as the control group. The sSELP, β-thromboglobulin, and platelet factor 4 plasma levels were measured before and after a single 4-hour HD session on a cuprophane dialyzer. The basal β-thromboglobulin and platelet factor 4 plasma levels were significantly increased in both HD groups compared with healthy controls but did not change after a single HD session, except for a significant decrease of platelet factor 4 in the non-EPO group. The predialysis sSELP plasma levels did not differ significantly compared with those of the healthy controls, but there was a significant increase of sSELP levels after a single HD session in both groups (EPO, P < .005; non-EPO, P < .05, respectively). These results suppose that the increased sSELP level was released from platelets during the course of a single HD session. The more significant increase of the sSELP plasma levels in EPO group during HD indicates that platelets are more activated in patients with long-term rHuEPO treatment, and this fact could partially explain the suspected tendency for thrombosis in these patients.

Is Gas6 Protein Associated With Sticky Platelet Syndrome

The aim of this study was to detect the prevalence of the polymorphisms of growth arrest—specific gene 6 (Gas6; Gas6 c. 834 + 7G > A) in patients with sticky platelet syndrome (SPS). Sticky platelet syndrome is a hereditary, autosomal dominant thrombophilia characterized by platelet hyperaggregation after low concentrations of platelet inducers—adenosine diphosphate (ADP) and epinephrine (EPI). The cause of SPS still remains unknown, but in recent years it was suggested that Gas6 protein may have a potential role in the pathogenesis of SPS. To assess the Gas6 polymorphisms (Gas6 c. 834 + 7G > A), 128 patients with SPS were included in the study and examined by polymerase chain reaction (PCR) method. GG genotype was detected in 63 (49.2%) patients, GA genotype in 53 (41.4%) patients, and AA genotype in 12 (9.4%) patients. The results in controls did not differ significantly compared to patients with SPS. Our findings did not prove allele A to be less associated with thrombosis and that ‘‘prothrombotic’’ allele G may be associated with higher risk of thrombosis. We cannot support the idea that Gas6 protein and Gas6 polymorphisms may be associated with thrombosis in SPS.

The prevalence of the platelet glycoprotein VI polymorphisms in patients with sticky platelet syndrome and ischemic stroke.

Abstract Introduction The aim of the study was to evaluate the genetic variability of the GP6 gene in patients with sticky platelet syndrome (SPS), a disorder characterized by platelet hyperaggregability, and thus to identify the genetic changes of the glycoprotein VI with possible relation to the platelet hyperaggregability. Patients and methods Seventy-one patients with SPS, clinically manifested as ischemic stroke, and 77 controls without SPS and with negative personal history of thromboembolic events were involved. SPS was diagnosed by platelet aggregometry (PACKS-4 aggregometer, Helena Laboratories) according to the method and criteria described by Mammen and Bick. Seven single-nucleotide polymorphisms (SNPs) of the GP6 gene (rs1654410, rs1671153, rs1654419, rs11669150, rs1613662, rs12610286, and rs1654431) were evaluated with the use of restriction-fragment-length polymorphism analysis. Results All allele and genotype frequencies were comparable between both SPS patients and the control group with no statistically significant differences. The haplotype analysis showed a higher occurrence of the one major haplotype (TTGTGA, 0.228 vs. 0.174; odds ratio (OR) 1.421; confidence interval (CI) 0.799–2.526) and two minor haplotypes (CGATAA, 0,026 vs. 0,006; OR 4.117; CI 0.443–38.25; TTGTGG, 0.018 vs. 0.009; OR 2.107; CI 0.259–17.12) in patients with SPS. None of haplotype differences was statistically significant. However, both the allele G of SNP rs12610286 (P = 0.029; OR 2.411; CI 1.134–5.123) and one major haplotype (TTGTGA; P = 0.012; OR 2.749; CI 1.223–6.174) were found significantly more frequent in patients with SPS type I in comparison with controls. Conclusion Our results, especially higher occurrence of four haplotypes in SPS patients, can support an idea that variability of the GP6 gene may be associated with the platelet hyperaggregability in SPS.

Heparin-induced Thrombocytopenia Presenting With Deep Venous Thrombosis and Pulmonary Embolism Successfully Treated With Rivaroxaban: Clinical Case Report and Review of Current Experiences.

Abstract: Heparin-induced thrombocytopenia (HIT) is a life or limb-threatening thrombotic thrombocytopenia. HIT is traditionally treated with factor-IIa inhibitors such as bivalirudin, lepirudin, or argatroban. However, these agents usually require parenteral administration and are not generally available in all countries. Recently, several experiences with novel oral anticoagulants (NOACs) administration to treat HIT had been reported. NOACs generally offer advantages such as consistent and predictable anticoagulation, oral administration with good patient compliance, and a good safety profile. We report a case of HIT with severe thrombotic complications successfully treated with rivaroxaban and discuss the current knowledge about the use of NOACs for the treatment of this potentially fatal thrombocytopenia.

Thrombin Receptor Agonist Peptide–Induced Platelet Aggregation Is Reduced in Patients Receiving Dabigatran

The availability of direct oral anticoagulants has caused a paradigm shift in thrombosis management. The direct thrombin inhibitor dabigatran seems to obstruct tenase complex by inhibiting thrombin generated in the initial phase and feed back to the amplification phase of cell-based coagulation reactions. However, it is still not fully understood if and how dabigatran impact platelet function. This observational study aimed to assess in vitro platelet function in patients with atrial fibrillation receiving dabigatran. Platelet aggregability was tested with platelet-rich plasma using platelet aggregometry (PACKS-4 aggregometer). Blood samples were stimulated with thrombin receptor agonist peptide (TRAP; 32 μmol/L). Results: A total of 28 patients with nonvalvular atrial fibrillation were enrolled. The mean age was 71.57 (9.75) years (range: 50-87 years), 16 patients were women, and the mean CHA2DS2VASc score was 3.93 (1.41). All patients began treatment with dabigatran as initial anticoagulant treatment. The minimum term use of dabigatran was 18 days. Dabigatran doses were 110 mg (57.14%) or 150 mg (42.86%) twice daily. The TRAP-induced platelet aggregation was significantly lower 2 hours after taking dabigatran compared to baseline value (79.39 [13.38] vs 90.14 [10.5]). Conclusion: The TRAP-induced platelet aggregation was reduced in cardiovascular patients 2 hours after receiving dabigatran. Our findings could have some important clinical implications because platelet aggregation and coagulation cascade are affected at the same time.

Sticky platelet syndrome: an important cause of life-threatening thrombotic complications.

Sticky platelet syndrome (SPS) is a prothrombotic thrombocytopathy with familial occurrence, characterized by hyperaggregability of platelets in response to adenosine diphosphate (ADP), epinephrine (EPI) or both. The syndrome has been identified in approximately 21% of unexplained arterial thrombotic episodes, regarded to be the most common thrombophilia in arterial thrombosis and 13.2% of unexplained venous thromboembolism (VTE). The relatively young age at the first manifestation, relation to fertility and pregnancy, seriousness of the symptoms, easy and effective management of the disorder indicate to the necessity to take it into account in the differential diagnosis of the underlying cause of the thrombotic event. As the various localizations of the thrombosis in SPS have been reported, its management often requires a multidisciplinary approach. This review deals with the clinical aspects of thrombophilia, its etiopathogenesis, diagnosis as well as novel advances in the treatment and outlines the challenges for the further research.

Does type 2 diabetes affect the on-treatment levels of direct oral anticoagulants in patients with atrial fibrillation?

AIMS Type 2 diabetes (T2D) is connected with several abnormalities in haemostasis; and with higher risk of stroke and systemic embolism in patients with non-valvular atrial fibrillation (NV-AF). However, it is recently unknown whether T2D affects the activity of direct oral anticoagulants (DOACs). The aim of this study was to determine the impact of T2D on DOACs activity in patients with NV-AF. METHODS This pilot prospective study enrolled totally 65 patients with NV-AF (20 dabigatran-treated, 110 mg/twice daily; 28 rivaroxaban-treated, 15 mg/daily; 17 apixaban-treated, 5 mg/twice daily). 25 patients had T2D (8 dabigatran-treated, 11 rivaroxaban-treated, and 6 apixaban-treated). DOAC activity was tested with Hemoclot® Thrombin Inhibitor assay in dabigatran-treated patients, and with factor Xa-calibrated anti-Xa chromogenic analysis in rivaroxaban- and apixaban-treated patients prior and two hours after drug administration. RESULTS There were no significant differences in dabigatran baseline (62.1 ± 8.0 vs. 51.8 ± 38.9 ng/ml, p = .76) and 2-h-post-drug-administration (91.7 ± 57.2 vs. 72.2 ± 33.2 ng/ml, p = .48) activity comparing T2D and non-diabetic patients. Similarly, no significant differences were found in rivaroxaban baseline (35.9 ± 22.5 vs. 55.3 ± 45.1 ng/ml, p = .19) and 2-h-post-drug-administration (145.7 ± 74.1 vs. 202.6 ± 135.0 ng/ml, p = .22) anti-Xa activity. In addition, no significant differences were present in apixaban baseline (96.0 ± 54.5 vs. 63.9 ± 36.8 ng/ml, p = .24) and 2-h-post-drug-administration (151.0 ± 78.3 vs. 151.7 ± 59.1 ng/ml, p = .98) anti-Xa activity between T2D and non-diabetic patients. CONCLUSIONS This pilot study did not detect differences in DOACs activity according to T2D status in patients with NV-AF.

First Evidence: TRAP-Induced Platelet Aggregation Is Reduced in Patients Receiving Xabans:

The availability of direct oral anticoagulants has caused a paradigm shift in the management of thrombosis. Rivaroxaban and apixaban are 2 direct oral anticoagulants whose target specificity is activated factor X (FXa). However, it is still not fully understood if and how xabans impact platelet function. This observational study aimed to assess the in vitro platelet function in patients with atrial fibrillation receiving xabans. This was a single-center study quantifying platelet aggregation in 41 patients treated with apixaban or rivaroxaban by light transmission aggregometry. The thrombin receptor activating peptide (TRAP)-induced platelet aggregation was significantly lower 2 hours after taking rivaroxaban or apixaban compared to baseline value (56.15% [8.53%] vs 29.51% [12.9%]; P = .000). Moreover, concomitant use of angiotensin-converting enzyme blockers, proton pump inhibitors, and statins reduces the efficiency of xabans. The TRAP-induced platelet aggregation was reduced in patients with cardiovascular disease 2 hours after receiving xabans.