Several direct oral anticoagulants (DOACs) are now widely used in the prevention and treatment of thromboembolic events. Unlike vitamin K antagonists, DOACs exhibit predictable pharmacokinetics and pharmacodynamics. DOACs are to be administered at fixed doses without routine coagulation monitoring. However, in some patient populations or specific clinical circumstances, measurement of drug exposure may be useful, such as in suspected overdose, in patients with a haemorrhagic or thromboembolic event during treatment with an anticoagulant, in those with acute renal failure, or in patients who require urgent surgery. This article provides practical guidance on laboratory testing of DOACs in routine practice and summarizes the influence of DOACs on commonly used coagulation assays.
Auteur(s) : Francois Mullier, Yvan Cornet, Nicolas Neyman, Alex Dromelet, Monique Delos, Andre Bosly, Christian Chatelain, Bernard Chatelain UCL Mont-Godinne, Yvoir, Belgique Les envahissements a minima du sang et de la moelle par les lymphomes sont difficiles a mettre en evidence. Le cas rapporte ici illustre l’importance d’une interaction etroite entre la cytologie, l’histologie medullaire et la cytometrie en flux, et demontre l’interet d’une strategie « multicouleur [...]
After 14 days' bone marrow maturation, neutrophil granulocytes reach the tissues where for 1-2 days they form the army whose phagocytic function was described by llya Metchnikoff in 1882. At that time, Paul Ehrlich was developing his neutrophil secretory theory which had less success until it returned with a vengeance in the last decade. Neutrophils are not only phagocytes. Above all they are cells that secrete bactericidal effectors and regulators (amplifiers and modulators) of the inflammatory focus. More and more sophisticated methods are being used to study phagocytosis, from the point of view both of the mechanism of chemotaxis and its role in inflammation and of the mediators of oxygen-dependent bactericidal action (superoxide anion, oxygenated water, hydroxyl radicals, myeloperoxidase, halogen ions and superoxide dismutase). In addition, the importance of oxygen-independent bactericidal mechanisms has been confirmed by the discovery of proteins such as BPI (Bactericidal Permeability Increasing Protein). Study of neutrophil dysfunction throws light on a number of neutrophil regulatory and effector mechanisms; it also proves useful in explaining the recurrent infections observed in some congenital disorders (chronic granulomatous disease, the "lazy leucocyte syndrome", the Chediak-Higashi syndrome, ichthyrosis , Job's syndrome...) or those associated with transitory neutrophil disorders (measles, severe bacterial infection...). Neutropenia induced by some antibiotics is easily demonstrated, but the interactions between these antibiotics and neutrophils are complex: phagocyte concentration of antibiotic, neutrophil inactivation of antibiotic, effect of antibiotic on microbe-leucocyte interaction such as an alteration in phagocytic and chemotactic response. The neutrophil is the first blood cell to arrive at the inflammatory focus; it is also at the centre of the response, next to the humoral mediators which both act upon it and which it itself secretes.
Abstract Background There is currently no universal and standardized test available to phenotype plasma fibrinolytic system. Aims Our main aims were to evaluate the performances of the ‘global fibrinolysis capacity’ assay (GFC) performed with the Lysis Timer® instrument, and to study the influence of some preanalytical conditions. Method Euglobulin clot lysis time (ECLT) and GFC were performed under several preanalytical conditions. Results GFC showed satisfactory intra- and inter-run precision. Frozen controls and reagents showed stability over the studied period. There was no statistically significant difference between GFC assessed in plasma samples processed at 4 °C or at 20 °C. GFC assessed with frozen-thawed plasma samples was prolonged when compared to fresh samples ( p = 0.014). The centrifugation scheme had no influence on PAI-1 activity levels, GFC and ECLT. Reference interval for GFC ranges from 29.3 (C I90% = 26.9–31.9) to 49.5 (90% CI = 45.9–52.2) minutes. In addition, a preliminary study in 40 healthy volunteers and 43 adult patients referred for investigation of a bleeding disorder was conducted to compare GFC and ECLT assays in their ability to classify samples with shortened or prolonged clot lysis times. Disagreements between ECLT and GFC were observed for 23 samples (out of 83), most of them minor. Conclusion GFC is suitable and convenient for a broad clinical use and can be performed with frozen-thawed plasma samples. Unlike ECLT, GFC is designed to take into account the balance between inhibitors and activators of the fibrinolytic system and could detect both hypo- and hyperfibrinolytic states. Whether it is as suitable as or even better than ECLT to detect a bleeding tendency due to a hyperactive fibrinolytic system deserves to be properly investigated.
