Vitamin K antagonists, such as warfarin and phen-procoumon, are the first-line oral anticoagulants for primary and secondary prevention of cerebral embo-lism in patients with atrial fibrillation. Although vitamin K an...Vitamin K antagonists, such as warfarin and phen-procoumon, are the first-line oral anticoagulants for primary and secondary prevention of cerebral embo-lism in patients with atrial fibrillation. Although vitamin K antagonists can significantly decrease the risk of stroke, their use is limited by several important drawbacks, such as a narrow therapeutic window, the risk of intracranial and gastrointestinal bleeding, interactions with a number of drugs and nutrients, and the need for regular laboratory tests for therapy adjustment. Currently, new oral anticoagulants, such as direct thrombin inhibitors (e.g., dabigatran) and direct factor Xa inhibitors (e.g., apixaban, rivaroxaban), are being developed and tested in clinical trials. Dabigatran and rivaroxaban were recently approved for prevention of cerebral embolism in patients with atrial fibrillation. The ad-vantages of dabigatran in comparison to warfarin are a lower rate of major bleedings with dabigatran 110mg bid, a better efficacy with dabigatran 150mg bid, no clinically relevant interactions with other drugs and no need for routine coagulation monitoring. The disadvantages are the absence of antidote and the absence of routine laboratory tests for precise mea-surements of anticoagulant effect of direct thrombin/ factor Xa inhibitors. This review will focus on throm-bin and factor Xa inhibitors, which are new and promising oral anticoagulants for the prevention of cerebral embolism. We will discuss their pharmacol-ogical and clinical properties and provide the most recent updates on their clinical trials.展开更多
Two components of anticoagulant protein were isolated from the leech Haemendipsa yanyuanensis by heparin agarose affinity chromatography and ultracentrifugation. The determination of anticoagulant activity and cha...Two components of anticoagulant protein were isolated from the leech Haemendipsa yanyuanensis by heparin agarose affinity chromatography and ultracentrifugation. The determination of anticoagulant activity and characterization analysis of the protein using the method of chromogenic substrate indicates that the anticoagulant protein is thrombin specific but not factor Xa specific. The results lay a foundation for the research of the anticoagulant mechanism and application of anticoagulant protein from H. yanyuanensis.展开更多
A rapid, simple, and reproducible method for the preparation of porcine thrombin was investigated. Porcine prothrombin was isolated by carrying out isoelectric precipitation. Porcine thrombin was prepared from prothro...A rapid, simple, and reproducible method for the preparation of porcine thrombin was investigated. Porcine prothrombin was isolated by carrying out isoelectric precipitation. Porcine thrombin was prepared from prothrombin which was activated by the prothrombinase complex containing Factor Xa, Factor V, Ca2+ and phospholipids. Factor Xa and Factor V were isolated by DEAE-cellulose chromatography respectively. They were both identified by SDS-PAGE. Yields and specific activity of porcine thrombin were 107 μg per milliliter plasma and 4 U per milligram protein.展开更多
During human pregnancy, progesterone induced decidual cells protect against hemorrhage: 1) as endovascular trophoblast breech and remodel uterine blood vessels;and 2) in the third stage of labor following preterm and ...During human pregnancy, progesterone induced decidual cells protect against hemorrhage: 1) as endovascular trophoblast breech and remodel uterine blood vessels;and 2) in the third stage of labor following preterm and term delivery. De- cidual cells promote hemostasis through enhanced expression of tissue factor (TF), the primary initiator of hemostasis via thrombin generation, and plasminogen activator inhibitor-1, which inactivates tissue type plasminogen activator, the primary fibrinolytic agent. Abruptions (decidual hemorrhage) produce excess thrombin which acts as autocrine/paracrine inducer of decidual cell expressed matrix metalloproteinases and of neutrophil chemoattractant and activator, interleukin-8. The latter mediates aseptic abruption-related neutrophil infiltration. During abruptions, decidual cell and neutrophil-derived proteases effectively degrade the decidual and fetal membrane extracellular matrix to promote preterm premature rupture of the membranes and preterm delivery (PTD). Decidual cell-derived thrombin weakens the amniotic membrane and lowers decidual cell-expressed progesterone receptor levels by increasing phospho-ERK1/2 signaling. The resulting functional progesterone withdrawal accompanies PTD.展开更多
文摘Vitamin K antagonists, such as warfarin and phen-procoumon, are the first-line oral anticoagulants for primary and secondary prevention of cerebral embo-lism in patients with atrial fibrillation. Although vitamin K antagonists can significantly decrease the risk of stroke, their use is limited by several important drawbacks, such as a narrow therapeutic window, the risk of intracranial and gastrointestinal bleeding, interactions with a number of drugs and nutrients, and the need for regular laboratory tests for therapy adjustment. Currently, new oral anticoagulants, such as direct thrombin inhibitors (e.g., dabigatran) and direct factor Xa inhibitors (e.g., apixaban, rivaroxaban), are being developed and tested in clinical trials. Dabigatran and rivaroxaban were recently approved for prevention of cerebral embolism in patients with atrial fibrillation. The ad-vantages of dabigatran in comparison to warfarin are a lower rate of major bleedings with dabigatran 110mg bid, a better efficacy with dabigatran 150mg bid, no clinically relevant interactions with other drugs and no need for routine coagulation monitoring. The disadvantages are the absence of antidote and the absence of routine laboratory tests for precise mea-surements of anticoagulant effect of direct thrombin/ factor Xa inhibitors. This review will focus on throm-bin and factor Xa inhibitors, which are new and promising oral anticoagulants for the prevention of cerebral embolism. We will discuss their pharmacol-ogical and clinical properties and provide the most recent updates on their clinical trials.
文摘Two components of anticoagulant protein were isolated from the leech Haemendipsa yanyuanensis by heparin agarose affinity chromatography and ultracentrifugation. The determination of anticoagulant activity and characterization analysis of the protein using the method of chromogenic substrate indicates that the anticoagulant protein is thrombin specific but not factor Xa specific. The results lay a foundation for the research of the anticoagulant mechanism and application of anticoagulant protein from H. yanyuanensis.
文摘A rapid, simple, and reproducible method for the preparation of porcine thrombin was investigated. Porcine prothrombin was isolated by carrying out isoelectric precipitation. Porcine thrombin was prepared from prothrombin which was activated by the prothrombinase complex containing Factor Xa, Factor V, Ca2+ and phospholipids. Factor Xa and Factor V were isolated by DEAE-cellulose chromatography respectively. They were both identified by SDS-PAGE. Yields and specific activity of porcine thrombin were 107 μg per milliliter plasma and 4 U per milligram protein.
文摘During human pregnancy, progesterone induced decidual cells protect against hemorrhage: 1) as endovascular trophoblast breech and remodel uterine blood vessels;and 2) in the third stage of labor following preterm and term delivery. De- cidual cells promote hemostasis through enhanced expression of tissue factor (TF), the primary initiator of hemostasis via thrombin generation, and plasminogen activator inhibitor-1, which inactivates tissue type plasminogen activator, the primary fibrinolytic agent. Abruptions (decidual hemorrhage) produce excess thrombin which acts as autocrine/paracrine inducer of decidual cell expressed matrix metalloproteinases and of neutrophil chemoattractant and activator, interleukin-8. The latter mediates aseptic abruption-related neutrophil infiltration. During abruptions, decidual cell and neutrophil-derived proteases effectively degrade the decidual and fetal membrane extracellular matrix to promote preterm premature rupture of the membranes and preterm delivery (PTD). Decidual cell-derived thrombin weakens the amniotic membrane and lowers decidual cell-expressed progesterone receptor levels by increasing phospho-ERK1/2 signaling. The resulting functional progesterone withdrawal accompanies PTD.
