Introduction: Recently extracellular vesicles (exosomes, microparticles also referred to as microvesicles and apoptotic bodies) have attracted substantial interest as potential biomarkers and therapeutic vehicles. However, analysis of microparticles in biological fluids is confounded by many factors such as the activation of cells in the blood collection tube that leads to in vitro vesiculation. In this study we aimed at identifying an anticoagulant that prevents in vitro vesiculation in blood plasma samples. Materials and Methods: We compared the levels of platelet microparticles and non-platelet-derived microparticles in platelet-free plasma samples of healthy donors. Platelet-free plasma samples were isolated using different anticoagulant tubes, and were analyzed by flow cytometry and Zymuphen assay. The extent of in vitro vesiculation was compared in citrate and acid-citrate-dextrose (ACD) tubes. Results: Agitation and storage of blood samples at 37°C for 1 hour induced a strong release of both platelet microparticles and non-platelet-derived microparticles. Strikingly, in vitro vesiculation related to blood sample handling and storage was prevented in samples in ACD tubes. Importantly, microparticle levels elevated in vivo remained detectable in ACD tubes. Conclusions: We propose the general use of the ACD tube instead of other conventional anticoagulant tubes for the assessment of plasma microparticles since it gives a more realistic picture of the in vivo levels of circulating microparticles and does not interfere with downstream protein or RNA analyses.© 2013 Elsevier Ltd. All rights reserved. IntroductionExtracellular vesicles (EVs) are membrane surrounded structures of various sizes (30-5000 nm) that have received significant attention recently [1]. EVs may be classified on the basis of their biogenesis, diameter and membrane markers. The two best characterized types of EVs include exosomes of endosomal origin and plasma membrane-derived microparticles (MPs) (recently often referred to also as microvesicles or ectosomes in the literature) [1]. EVs are present in all biological fluids including blood plasma, synovial fluid, cerebrospinal fluid, urine, tears and breast milk [1]. MPs are in between 100 and 1000 nm in diameter, and they are also detectable by flow cytometry [2,3]. Thus, MP profiles are easily analyzed in the routine clinical laboratory practice, and represent novel biomarkers of various diseases. In circulation, most MPs are derived from platelets, red blood cells, endothelial cells and leukocytes. Because of their abundance, platelet-derived MPs (PMPs) received the highest attention during the past few years. Elevated PMP counts are characteristic for nearly all autoimmune disorders [4,5], and also for several cardiovascular and metabolic diseases [1]. EVs not only contain proteins but also RNA molecules [1]. Extracellular RNA (exRNA) in blood plasma is encapsulated in EVs, or bound to either proteins or HDL molecules [6]. exRNAs, particularly miRNAs, are specific and sensitive biomarkers...

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Our cohort study did not find any evidence for an increased risk of thromboembolism during treatment with pdC1-INH, despite the presence of multiple predisposing factors.

Test conditions may have profound impacts on the obtained results with the Multiplate assay. Our findings highlight the large influence of the time from sample collection until testing, suggesting that measurements should be performed within an hour of blood collection.

A trombin a véralvadási kaszkád egyik kulcsenzime, amely mind pro-, mind antikoaguláns funkcióval rendelkezik. Központi szerepe folytán a trombin képződése a véralvadási folyamat egyik legfontosabb lépése, amely az úgynevezett trombingenerációs vizsgálattal jellemezhető. A trombingeneráció globális véralvadási teszt, amely átfogó képet ad a haemostasis állapotáról. Karakterisztikáját egyaránt befolyásolják a pro-és az antikoaguláns folyamatok, ezáltal alkalmas a fokozott trombóziskészség és a vérzékenység kimutatására is. Klinikai vizsgálatok igazolják a trombingeneráció fokozódását vénás és artériás trombózishajlam esetében. Segíthet az antikoaguláns terápia monitorozásában, faktorinhibitorokkal történő antikoaguláns kezelés esetében is. A trombingenerációs vizsgálatok eredményei hemofília esetén jól tükrözik a vérzés súlyosságát, és monitorozható a faktorkészítményekkel történő terápia. Információt adhat azokban az esetekben is, amikor a hemofíliás betegnél inhibitorok jelennek meg, és emiatt speciális kezelésre van szükség. A klinikai gyakorlatban történő alkalmazáshoz elengedhetetlen a módszer standardizálása és a klinikai dön-téshozatalhoz szükséges küszöbértékek meghatározása. Orv. Hetil., 2014, 155(22), 851-857. Kulcsszavak: véralvadási vizsgálatok, trombózis, vérzékenység, trombin Thrombin generation assays and their clinical applicationThrombin is a key enzyme of the coagulation system, having both pro-and anticoagulant functions. Thus, the generation of thrombin is one of the most important steps in coagulation. Global haemostasis assay, the so-called thrombin generation test is appropriate for its assessment. Since thrombin generation is sensible for both pro-and anticoagulant processes it can be applied for the general characterisation of the risk of thrombosis and bleeding, too. Clinical studies confi rmed augmented thrombin generation in patients with high risk of venous or arterial thrombosis. Anticoagulant therapy (also novel oral anticoagulant treatment) can be monitored by thrombin generation. In case of haemophilia thrombin generation assays refl ect bleeding severity. It is applicable for monitoring of both conventional haemophilia treatment and inhibitor-bypassing therapy, which is needed when inhibitors develop in patients. Standardization of thrombin generation methods and determination of cut off values are required before its application in clinical practice.