Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.5 (thrombin)
33,306 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The platelet plays a pivotal role in maintaining vascular integrity. In a manner similar to leukocytes, platelets interact with selectins expressed on activated endothelium. P-selectin glycoprotein ligand 1 (PSGL-1) is the main P-selectin ligand expressed on leukocytes. Searching for platelet ligand(s), we used a P-selectin-immunoglobulin G (IgG) chimera to affinity purify surface-biotinylated proteins from platelet lysates. P-selectin-bound ligands were eluted with ethylenediaminetetraacetic acid. An approximately 210-kD biotinylated protein was isolated from both human neutrophil and platelet preparations. A band of the same size was also immunopurified from human platelets using a monoclonal anti-human PSGL-1 antibody and could be blotted with P-selectin-IgG. Under reducing conditions, both the predicted PSGL-1 approximately 210-kD dimer and the approximately 120-kD monomer were isolated from platelets. Comparative immunoelectron microscopy and Western blotting experiments suggested that platelet PSGL-1 expression is 25-100-fold lower than that of leukocytes. However, patients with chronic idiopathic thrombocytopenic purpura who harbor predominantly young platelets displayed greater expression, indicating that PSGL-1 expression may be decreased during platelet aging. By flow cytometry, thrombin-activated platelets from normal individuals exhibited greater expression than those unstimulated. An inhibitory anti-PSGL-1 antibody significantly reduced platelet rolling in mesenteric venules, as observed by intravital microscopy. Our results indicate that functional PSGL-1 is expressed on platelets, and suggest an additional mechanism by which selectins and their ligands participate in inflammatory and/or hemostatic responses.
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PMID:P-Selectin glycoprotein ligand 1 (PSGL-1) is expressed on platelets and can mediate platelet-endothelial interactions in vivo. 1077 Aug 6

The management of unexpected bleeding must be directed at the specific abnormality identified, as there is no universally effective and safe procoagulant product. Where practical, a purely pharmaceutical approach obviates the residual risks of exposure to plasma-derived products. Desmopressin is often effective in bleeding due to mild haemophilia A, Type I von Willebrand's disease and some platelet function disorders. Where replacement therapy is necessary, it should be as specific as possible, preferably using purified components singly or in combination. Recombinant proteins provide the greatest margin of safety, but it must be borne in mind that these are biologicals, and that they may contain human and animal plasma-derived proteins. Where specific replacement is unavailable or impractical, plasma or crudely fractionated plasma derivatives may be used. In the case of inhibitor antibodies to factor VIII, high dose human factor VIII or porcine factor VIII may be used. Where replacement therapy is impossible due to a high inhibitory titre, it may be necessary to bypass the specific haemostatic defect using activated prothrombin complex concentrates or recombinant activated factor VIIa. The latter product is being studied in patients with various disorders of platelet function, and in the more global haemostatic failure that accompanies end-stage liver disease. Ancillary methods are often of great value in securing haemostasis. These may be derived from pharmacological or biological sources, and their sites of action may be systemic or topical. Examples include antifibrinolytic lysine analogues, corticosteroids where inflammation accompanies bleeding, and the topical application of fibrin sealants or thrombin. Simple physical measures such as pressure, ice, or splinting are also valuable adjunctive measures. Finally, it must be emphasized that the ultimate control of bleeding often depends upon effective management of the inciting cause, such as eliminating the trigger for DIC, or suppressing the causative antibody of ITP. These principles will be presented using a practical algorithmic approach. The initial question when considering treatment should be whether or not the patient is acutely unstable. Instability may be due to one of two causes: the volume of blood loss leading to a compromised cardio-vascular status, or the site of the bleed. The relevance of the site of the bleed is independent of the volume of blood loss, so for example, a closed bleed into CNS will cause critical functional compromise even though the volume of bleeding may be minimal. Similarly bleeding into a compartment, such as into a forearm or a calf will cause critical functional compromise irrespective of the volume of bleeding.
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PMID:Unexpected bleeding disorders: Algorithm for approach to therapy. 1125 56

For a long time fibrinopeptide A(FPA), fibrinopeptide B(FPB), D-dimer, FM test, serum FDP, and thrombin anti-thrombin complex(TAT) are being used as molecular markers to for sure diagnose hypercoagulable state and thrombus formation. Indeed these molecular markers are very useful for diagnosing thrombus formation, disseminated intravascular coagulation(DIC), and the indicator of treatment of DIC. But these molecular parameters are not enough and difficult for prognosis of the disease or predicting the complication of patients as the most important subject for clinicians. The soluble fibrin monomer-fibrinogen complex (SF) is a complex coupling fibrin monomer and fibrinogen molecules to be formed in the early-activated state of blood coagulation. Thus such a molecular complex is expected to serve as a parameter for the diagnosis of thrombus formation and DIC, in particular its early stage. The aim of the present study is to evaluate a potential usefulness of a newly developed SF test utilizing an SF specific monoclonal antibody (IF-43). We measured SF together with established other parameters in 195 patients with DIC, subclinical DIC/hypercoagulable state, and non-DIC. The diagnosis of DIC was made based on a modified version of the criteria established by the Ministry of Health, Labor and Welfare of Japan. Underlying disease includes leukemia, malignant lymphoma, myelodysplastic syndrome (MDS), multiple injury, giant ovarian tumor, prostatic cancer with multiple bone metastasis, lung cancer, breast cancer with multiple lung and bone metastasis, severe pneumoniae, sepsis, hemophagocytic syndrome (HPS), and rheumatoid arthritis. The SF levels in DIC patients were significantly higher than those in the subclinical DIC/hypercoagulable state, and the non-DIC patients. Receiver operating characteristic (ROC) analysis shows that the specificity and sensitivity of the SF assay appears to be satisfactory. As the level of SF reflects the thrombin generation activity in plasma, it would serve as a strong tool to selectively kick up the state of thrombin generation. These results indicate that the SF could be a specific and reliable parameter for the diagnosis of DIC and contribute to legitimate managements of patients with DIC. The excessive life response to serious clinical insults, such as sepsis, severe pancreatitis, trauma and shock, is called systemic inflammatory response syndrome (SIRS). Once SIRS occurs, people may often die from serious complications such as adult respiratory distress syndrome (ARDS), acute lung injury (ALI), disseminated intravascular coagulation (DIC) and multiple organ failure (MOF). Especially, ALI followed by pneumoniae associated with SIRS could depend on patient's prognosis and life. That is to say, it seems to be urgent for clinicians to make differential diagnosis between Pneumoniae associated with SIRS and Coagulopathy (PASC) and Simple Pneumoniae (SP). Soluble fibrin monomer-fibrinogen complex(SF) is formed in the early-activated state of blood coagulation. Thus such a molecular complex is expected to serve as a parameter for the diagnosis of coagulopathy, in particular its early stage. The aim of the present study is to make differential diagnosis between Pneumoniae associated with SIRS and Coagulopathy (PASC) and Simple Pneumoniae(SP) by using a newly developed SF test utilizing an SF specific monoclonal antibody (IF-43). We measured SF together with established other parameters, hemogram, blood laboratory items in 7 patients with PASC and 17 patients with SP. The diagnosis of Pneumoniae was defined according to the criteria: clinical symptoms abnormal shadow in both Chest X-p and Chest CT, increased level of CRP, number of WBC. The diagnosis of SIRS was based on the criteria established by American College of Chest Physicians (ACCP)/Society of Critical Care Medicine (SCCM) Consensus Conference held in August of 1991 in Northbrook, IL (USA). Underlying disease includes leukemias, malignant lymphoma, myelodysplastic syndrome (MDS), multiple myeloma, idiopathic thrombocytopenia purpura(ITP), multiple injury (bone fracture), cerebral hemorrhage, enterocolitis, Appendicitis, lung cancer, larynx cancer, bronchiolitis obliterans organizing pneumonia(BOOP), chronic obstructive pulmonary disease(COPD), sepsis. The SF levels in PASC patients are significantly higher than those in SP patients (p < 0.001). Otherwise, there is no significant difference of the CRP levels between in PASC group and SP group (p < ns). There is no co-relationship between SF level and D-dimer level. Receiver operating characteristic (ROC) analysis shows that the specificity and sensitivity of the SF assay appears to be quite satisfactory. As the level of SF reflects the thrombin generation activity in plasma, it would serve as a strong tool to selectively kick up the state of thrombin generation. These results indicate that the SF could be a specific and reliable parameter for the diagnosis of PASC and contribute to legitimate managements of patients with PASC.
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PMID:[A novel molecular marker for thrombus formation and life prognosis--clinical usefulness of measurement of soluble fibrin monomer-fibrinogen complex (SF)]. 1516 5

The diagnosis and management of thrombocytopenia is a growing component in the practice of hematology. The frequency with which hematologists are called in consultation for thrombocytopenia continues to increase with the advent of routine automated platelet determinations and the introduction of new medications. For most patients, such as those with inherited and auto-immune thrombocytopenia, emphasis is focused on efforts to treat or forestall bleeding without excess drug-induced toxicity or burden to the patient. However, in disorders such as heparin-induced thrombocytopenia (HIT), avoidance of thrombotic complications is the key to management. In this chapter, we provide the pediatric and adult hematologist with new insights into the pathogenesis and recognition of congenital inherited thrombocytopenias (CTP), a hitherto difficult to comprehend constellation of clinical entities. We also highlight new approaches to the diagnosis and treatment of two of the more common thrombocytopenic conditions encountered in practice, autoimmune or idiopathic thrombocytopenic purpura (ITP) and HIT. In Section I, Dr. James Bussel discusses CTPs and their distinction from childhood ITP. He emphasizes the clinical features that enable the pediatrician and hematologist to suspect the diagnosis of CTP and those that are of use to subcategorize the various entities, where possible. He also emphasizes newer molecular markers that afford definitive diagnosis in some cases and provide insight into platelet production. This section highlights the characteristic associated findings and differences in the natural history and approaches to management of the various entities. In Section II, Dr. Robert McMillan discusses adult chronic ITP. He revisits the utility of platelet antibody determination in diagnosis and review new insights into pathogenesis. The role of Helicobacter pylori infection and the timing of splenectomy in the management of acute and emergent ITP are examined. New insights into the natural history of ITP post-splenectomy and management strategies for patients with severe, chronic, refractory ITP are discussed. In Section III, Dr. James Zehnder updates us on HIT. He emphasizes new insights into the clinical presentation and pathogenesis of this condition. He critically reviews the utility of laboratory testing for heparin-dependent antibodies. Recent studies on the use of direct thrombin inhibitors are examined and the management of cardiopulmonary bypass surgery in patients with HIT is discussed.
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PMID:Congenital and acquired thrombocytopenia. 1556 94

Efficiency of recombinant activated factor VII (rFVIIa) (NovoSeven) in treatment of patients with idiopathic thrombocytopenic purpura (ITP) complicated with subarachnoid and parenchimatous hemorrhage was shown in the article. The action of NovoSeven in patients with an affected megakaryocytic system depends on the binding of rFVIIa with activated thrombocites and on their surface rFVIIa provides the activation of X factor and thrombin formation. NovoSeven proved to be called a universal hemostatic medication for the idiopathic thrombocytopenic purpura treatment. Taking into account that transfusion of thrombocites concentrate is not recommended for patients with thrombocytopenia of immune origin and after immunoglobulin infusion we need time to see thrombocites number grow so in urgent NovoSeven is a medication of choice to stop bleeding in patients with ITP.
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PMID:[Use of recombinant activated factor VII (NovoSeven) in the treatment of a patient with idiopathic thrombocytopenic purpura complicated with subarachnoid and parenchimatous hemorrhage]. 1572 22

Direct thrombin inhibitors are commonly used anticoagulants in patients with known or suspected heparin-induced thrombocytopenia (HIT). All three direct thrombin inhibitors available in the United States-argatroban, bivalirudin, and lepirudin-are pregnancy category B drugs based on animal studies, but little data are available on the safety of these agents during human pregnancy. Whereas several case reports support the safe use of lepirudin, only one case report has been published with argatroban and none with bivalirudin. We describe a 26-year-old pregnant woman with portal vein thrombosis and thrombocytopenia treated with argatroban for possible HIT during her last trimester. An argatroban infusion was started at 2 microg/kg/minute during her 33rd week of pregnancy, with the dosage titrated based on the activated partial thromboplastin time; infusion rates ranged from 2-8 microg/kg/minute. Treatment continued until her 39th week of pregnancy, when labor was induced. Argatroban therapy was discontinued 7 hours before epidural anesthesia. The patient successfully delivered a healthy male newborn, devoid of any known adverse effects from argatroban. The infant was found to have a small ventricular septal defect and patent foramen ovale at birth, but it is unlikely that these were caused by argatroban since organogenesis occurs in the first trimester. Even though the cause of this patient's thrombocytopenia was later determined to be idiopathic thrombocytopenic purpura, this is an important case that adds to the literature on use of argatroban during pregnancy.
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PMID:Successful use of argatroban during the third trimester of pregnancy: case report and review of the literature. 1902 34

Glycocalicin (GC) is a large extracellular proteolytic fragment of glycoprotein Ib, a membrane platelet component playing an essential role in the physiological processes of platelet adhesion and aggregation. GC contains the binding sites for thrombin and von Willebrand factor. GC circulates normally in vivo in significant concentrations and the plasma level of this protein reflects a complex function of factors including platelet count or platelet turnover. It can therefore serve as a good indicator for many diseases like hypoplastic thrombocytopenia and idiopathic thrombocytopenic purpura. For this reason, several purification assays have been previously described. In this work, we describe a novel analytical method for GC purification from human platelets based on preparative HPLC gel filtration followed by immuno-affinity chromatography on NHS activated column conjugated with specific antibody. Pure GC was obtained from tiny amount of starting material. Our protocol of GC purification is simple, fast and provides a pure end product.
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PMID:Purification of glycocalicin from human plasma. 2660 9

Platelets are small anucleate blood cells generated from megakaryocytes in the bone marrow and cleared in the reticuloendothelial system. At the site of vascular injury, platelet adhesion, activation and aggregation constitute the first wave of hemostasis. Blood coagulation, which is initiated by the intrinsic or extrinsic coagulation cascades, is the second wave of hemostasis. Activated platelets can also provide negatively-charged surfaces that harbor coagulation factors and markedly potentiate cell-based thrombin generation. Recently, deposition of plasma fibronectin, and likely other plasma proteins, onto the injured vessel wall has been identified as a new "protein wave of hemostasis" that may occur even earlier than the first wave of hemostasis, platelet accumulation. Although no experimental evidence currently exists, it is conceivable that platelets may also contribute to this protein wave of hemostasis by releasing their granule fibronectin and other proteins that may facilitate fibronectin self- and non-self-assembly on the vessel wall. Thus, platelets may contribute to all three waves of hemostasis and are central players in this critical physiological process to prevent bleeding. Low platelet counts in blood caused by enhanced platelet clearance and/or impaired platelet production are usually associated with hemorrhage. Auto- and allo-immune thrombocytopenias such as idiopathic thrombocytopenic purpura and fetal and neonatal alloimmune thrombocytopenia may cause life-threatening bleeding such as intracranial hemorrhage. When triggered under pathological conditions such as rupture of an atherosclerotic plaque, excessive platelet activation and aggregation may result in thrombosis and vessel occlusion. This may lead to myocardial infarction or ischemic stroke, the major causes of mortality and morbidity worldwide. Platelets are also involved in deep vein thrombosis and thromboembolism, another leading cause of mortality. Although fibrinogen has been documented for more than half a century as essential for platelet aggregation, recent studies demonstrated that fibrinogen-independent platelet aggregation occurs in both gene deficient animals and human patients under physiological and pathological conditions (non-anti-coagulated blood). This indicates that other unidentified platelet ligands may play important roles in thrombosis and might be novel antithrombotic targets. In addition to their critical roles in hemostasis and thrombosis, emerging evidence indicates that platelets are versatile cells involved in many other pathophysiological processes such as innate and adaptive immune responses, atherosclerosis, angiogenesis, lymphatic vessel development, liver regeneration and tumor metastasis. This review summarizes the current knowledge of platelet biology, highlights recent advances in the understanding of platelet production and clearance, molecular and cellular events of thrombosis and hemostasis, and introduces the emerging roles of platelets in the immune system, vascular biology and tumorigenesis. The clinical implications of these basic science and translational research findings will also be discussed.
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PMID:Platelets are versatile cells: New discoveries in hemostasis, thrombosis, immune responses, tumor metastasis and beyond. 2728 65


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