Detection of clopidogrel resistance using ADP induced aggregometry with specific inhibitor PGE1.

BACKROUND: Antiaggregation therapy is still the most frequently used approach to prevent thrombotic events in cardiovascular diseases. It has a good clinical effect but increasing evidence shows high residual platelet aggregation activity in a number of patients. Laboratory methods only allow us to detect clopidogrel "non-responders" or "low responders". Recent methods are based on monitoring residual platelet aggregation activity (aggregation methods) or detecting the number of free epitopes for binding a specific monoclonal antibody such as vasodilator-stimulated phosphoprotein phosphorylation (VASP). METHODS: The aims of our study were comparison light transmission aggregometry (LTA) and multiple electrode platelet aggregometry (MEA) with induction by ADP in concentrations of 20 micromol/L with or without prostaglandin E1 (PGE1) for monitoring clopidogrel resistance. RESULTS: In the group of 84 patients with cardiovascular disease (CAD) studied, an impaired individual response to clopidogrel therapy was found 11.9% and 10.7% of the patients using MEA and LTA, respectively, induced by ADP with PGE1. The LTA and MEA methods with induction by ADP with PGE1 and without PGE1 were statistically compared using Spearman's nonparametric correlation analysis. Both methods with using PGE, showed a positive significant correlation (p = 0.003) in contrast with the results without PGE1 with a no significant correlation (p = 0.732). CONCLUSIONS: The sensitivity for detecting clopidogrel resistance correlates well with other data in the literature suggesting that there are 5%-30% clopidogrel low-responders depending on the type of platelet function assay used and the criteria for defining a low-responder [16-18]. These results favor implementation of the ADP test with PGE1 by MEA specifically for identification of low-responders to clopidogrel.

The assessment of aspirin resistance by using light transmission and multiple electrode aggregometry.

INTRODUCTION: The issues related to aspirin [acetylsalicylic acid (ASA)] resistance are still under debate. Depending on the method of assessment and studied patients, the prevalence of ASA resistance is rather heterogeneous, ranging from 5% to 45%. The method most commonly used for assessing platelet function is their aggregation. ASA irreversibly inhibits cyclooxygenase-1 (COX-1) by acetylation. METHODS: This study aimed to compare light transmission aggregometry (LTA) and multiple electrode aggregometry (MEA) for the measurement of ASA resistance, using arachidonic acid as an inducer of the reaction. RESULTS: The study comprised 101 patients with stable ischemic heart disease taking a daily dose of 100 mg of ASA. The rates of ASA resistance were 22.22% and 21.21% as detected by LTA and MEA, respectively. The two methods were statistically compared using Spearman's nonparametric correlation analysis, with a positive significant correlation (P=0.01) and medium positive dependence between the methods (r=0.0539). CONCLUSION: If ASA resistance is detected by laboratory tests, replacement of ASA or its combination with other antiplatelet drugs as well as increased dosage may be considered.

The MAPK-dependent regulation of the Jagged/Notch gene expression by VEGF, bFGF or PPAR gamma mediated angiogenesis in HUVEC.

The Jagged-Notch signalling, plays a crucial role in cell differentiation. Angiogenesis, is regulated by VEGF, bFGF as well as by the free fatty acid metabolites , which are regulators of transcription factors such as peroxisome proliferation activating receptors (PPARs). The study analyzed the signalling pathways involved in the regulation of Jagged-1/Notch-4 expression in endothelial cells (HUVECs) in response to VEGF, bFGF and PPAR-gamma exogenous activator - ciglitazone. HUVECs were incubated with investigated substances for 24 hours, with or without the presence of the MAP-kinases inhibitors were used. Jagged-1 and Notch-4 gene expression was determined using quantitative Real-Time PCR. The Jagged-1/Notch-4 protein expression was compared by flow cytometry, when the phosphorylation-dependent activation of kinases was estimated by Western-blot method. The opposite effect of VEGF, bFGF, or ciglitazone on the Jagged-1/Notch-4 expression on HUVEC was connected with the different activation of MAPKs. Ciglitazone, activated p38 MAPK pathway and simultaneously inhibited phosphorylation of p42/44 MAPK. The pro-angiogenic: bFGF and VEGF, also activated the p38 MAPK, but they did not attenuate the p42/44 MAPK phosphorylation. Maintaining of the Jagged/Notch interactions by VEGF, when down-regulation by bFGF and ciglitazone, seems to be dependent on the different effect on p38 MAPK and p42/44 MAPK pathway regulation.

[Malignant arrhythmia in a patient with variant (Prinzmetal's) angina pectoris]. / Maligní arytmie u pacienta s variantní (Prinzmetalovou) anginou pectoris.

Malignant arrhythmia is a frequent complication of myocardial ischemia due to the occurrence of coronary artery spasm. The paper describes a patient with variant angina pectoris with an ICD implant who was repeatedly resuscitated for circulatory arrest in malignant arrhythmia. During myocardial ischemia the ECG showed elevations in the ST segments in the region of the ventral cardiac wall, with the formation of permanent polymorphous chamber tachycardia. External defibrillation was necessary due to recurrent tachyarrhythmias. A spasm developed when the RIA (radio immuno assay) was introduced during coronarography. The spasm started in the periphery of the artery and extended as far as the area of bifurcation with RD, with transitory closure of the artery and the development of chamber tachycardia. The patient fully recovered after the addition of Ca-blocker, nitrate depot and the withdrawal of the beta-blocker.