The effect of hirudin on antagonisting thrombin induced apoptosis of human microvascular endothelial cells

Abstract Purpose: To investigate whether hirudin exerts its antithrombin action to decrease the ratio of Human Microvascular Endothelial Cells (HMVECs) apoptosis. Methods: Human microvascular endothelial cells (HMVECs) cultured in the third and fifth generations were used. HMVECs were divided into normal group, thrombin group (T group), natrual hirudin group (H group), thrombin + natrual hirudin group (T + H group), AG490 group, thrombin + AG490 group (T + AG490 group), natrual hirudin + AG490 group (H + AG490 group), thrombin + natural hirudin + AG490 (T + H + AG490 group).Apart from the normal group, the other groups were exposed to the relevant drugs for 24 hours.HMVEC apoptosis was assessed by flow cytometric and double Immunofluorescence of phosphorylation of JAK (P-JAK2) and TUNEL assay. Results: Compared with the normal group, in thrombin group the HMVECs apoptosis rate were significantly increased (P<0.05).The results indicated that the index of apoptosis and the apoptosis rate were improved in cultures treated by natural hirudin (T + H group), relative to cultures with thrombin only (T group). We found that the index of apoptosis and the apoptosis rate in the AG490 + thrombin group were higher than that in the hirudin + thrombin group (P<0.05). Double Immunofluorescence of p-JAK2 and TUNEL assays showed that cells were double positive for P-JAK2 uptake and TUNEL detection liquid binding. Conclusion: The natural hirudin and JAK2/STATs signal inhibitor AG490 could block the effects of thrombin. Natural hirudin could attenuate HMVECs apoptosis via antagonizing thrombin and it is suggested that this effect may occur by blocking the JAK2/STATs signaling pathway and this signaling pathways appears to be not the only pathway.

Nuevos anticoagulantes y anestesia regional / New anticoagulants and regional anesthesia

En los últimos años se ha producido un incremento de la práctica de la anestesia regional en pacientes que reciben fármacos que afectan el sistema fisiológico de la coagulación. La posibilidad de producirse un hematoma espinal, luego de una punción neuroaxial, en este tipo de pacientes, intranquiliza al médico anestesista. Por lo tanto, es indispensable que el médico anestesista conozca los mecanismos de acción de los diferentes anticoagulantes, sus propiedades farmacológicas y farmacocinéticas para poder así definir el intervalo entre la administración de los fármacos anticoagulantes y el bloqueo neuroaxial, la retirada del catéter y el reinicio de la anticoagulación permitiendo asociar la anestesia regional y la anticoagulación de forma segura para el paciente¹. Este trabajo tiene como objetivo principal realizar una revisión de los nuevos fármacos anticoagulantes y analizar las recomendaciones existentes como para poder hacer un uso racional y seguro en nuestra práctica diaria.

New anticoagulants and regional anesthesia In recent years there has been an increase in the practice of regional anesthesia in patients receiving drugs affecting the physiological coagulation system. The possibility of a spinal hematoma occurs after neuraxial puncture in these patients, uneasy the anesthesiologist. Therefore, it is essential that the anesthesiologist know the mechanism of action of different anticoagulants, their pharmacological and pharmacokinetic properties to well define the interval between administration of anticoagulants and neuraxial blockade, catheter removal and resetting anticoagulation allowing associate regional anesthesia and anticoagulation safely for patient1. This work has as main objective to carry out a review of the new anticoagulant drugs and analyze existing recommendations as to make rational and safe use in our daily practice.

Analysis of Novel Anticoagulants for Atrial Fibrillation – Pharmacokinetics and Pharmacological Considerations.

Atrial Fibrillation (AF) is the most common arrhythmia. AF is a major risk factor for stoke. Warfarin has been available for more than 60 years and until recently it was the only oral anticoagulant used for the prevention of stroke. Despite the extensive studies and proven efficacy, its utility is limited by multiple factors. Warfarin interacts with a multitude of drugs and foods, has a delayed onset of action, has a narrow therapeutic range, requires routine lab monitoring and exhibits variable responses in patients. The novel agents dabigatran, rivaroxaban and apixaban have the potential to have some of the limitations of warfarin. This article will discuss the pharmacokinetic and pharmacological considerations and different characteristics of the novel anticoagulants when used for the prevention of AF.

Bivalirudin: a new promising direct antithrombin.

The deadliest manifestations of ischemic heart disease are initiated and propagated by intra-coronary thrombin generation. Thrombin is resistant to inactivation by heparin when it is bound to fibrin, fibrin degradation products or subendothelial collagen. Recognition of these limitations has led to development of a new class of antithrombin agents which directly target the active sites on the surface of thrombin molecule and are therefore designated as direct antithrombins. These agents do not need mediation of antithrombin III for their action and are not inhibited by platelet factor 4. This report focuses on bivalirudin, a new agent of promising impact on both interventional as well as non-interventional cardiology. It is a short acting anticoagulant which bivalently and directly inhibits thrombin (coagulation factor II). It binds the active (catalytic) site and the fibrinogen-binding site (exosite I). This provides high affinity and specificity for thrombin. Slow cleavage at the Arg3-Pro4 bond results in recovery of thrombin activity after discontinuation of bivalirudin. Bivalirudin inhibits both protease activated receptor 1 and 4 (PAR 1 and PAR 4) thereby effectively inhibiting acute thrombin mediated platelet aggregation. Clinical efficacy has been assessed and proved in over 20 published patient series focussing on patients with acute coronary syndrome with or without myocardial infarction, patients undergoing percutaneous coronary interventions, patients receiving various adjunctive anti-platelet medications, patients with heparin induced thrombocytopenia or patients undergoing cardiac surgery. In contrast to the well established unfractionated heparin, bivalirudin lacks the risk of heparin induced thrombocytopenia. It shows a tendency to lower bleeding risks without reduction of efficacy when compared with the two-pronged treatment with unfractionated heparin and glycoprotein IIb/IIIa inhibitors.