Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.6 (thromboplastin)
 13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Detailed coagulation studies were performed in a group of 19 patients with primary hepatocellular cancer (PHC) and the results were compared statistically with the findings in 19 control subjects. Various funcitonal and immunochemical methods were employed in determining the possible presence of functional or structural coagulant protein abnormalities. The patient group was characterized by prolonged prothrombin times, partial thromboplastin times, and Reptilase times, increased levels of fibrinogen, factor VIII, and factor VIII-related antigen, moderately devreased levels of factor V, factor IX, factor X, antithrombin III, and plasminogen, and reduced levels of factor II and factor VII. Functional, immunochemical, and biochemical analysis failed to detect the presence of acquired protein abnormalities. These findings indicate that hemostatic changes in primary hepatocellular cancer are nonspecific in character. Severe alterations in the plasma levels of one or more of these hemostatic factors may occur.
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PMID:Hemostatic factors in primary hepatocellular cancer. 19 99

Three children with haemophilia and antibodies to factor VIII were treated with a non-activated prothrombin concentrate (Prothrombinex) for 12 bleeding episodes. There was clear clinical response and joint aspirations were performed after infusions of phothrombinex in a dose of 30--50 factor IX units/kg body weight and there was no clinical evidence of thrombosis or febrile reactions. There was a significant shortening of the activated partial thromboplastin time (PTT) at one and four hours after the initial infusion with a return to pre-infusion levels 9--24 hours after infusion. The shortening in the PTT was less marked in subsequent infusions. There were no changes in the level of factor VIII procoagulant activity, factor VIII related antigen or factor VIII antibodies after the infusion. In two patients platelet function studies were unaltered by the infusion and in one patient procoagulant levels of factor II, IX and X were no greater than expected from the infusion. We conclude that infusions of non-activated prothrombin concentrates are clinically effective in the treatment of children with haemophilia and factor VIII antibodies but the mechanism of action is unknown.
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PMID:The use of non-activated prothrombin concentrate in the management of haemophilia A with factor VIII antibodies. 26 89

In four children with haemophilia A and antibodies to factor VIII, 18 bleeding episodes were randomized for treatment with factor VIII concentrate (30 units/kg) and 18 for treatment with a prothrombin-complex concentrate (prothrombinex) given in a dose of 30 units of factor IX/kg. Treatment with prothrombinex was associated with a better clinical response, a significantly greater shortening of the kaolin partial thromboplastin time and significantly lower incidence of post-infusion increase of levels of factor VIII antibodies. Although treatment with factor VIII concentrate was clinically successful in 15 episodes, treatment failures occurred in three instances leading to parental request for withdrawal from study in two families.
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PMID:A randomized study of factor VIII or prothrombin complex concentrate infusions in children with haemophilia and antibodies to factor VIII. 28 89

Plasma exchange has been proposed as a treatment for multiple disorders. Three patients with amyotropic lateral sclerosis, who were hemostatically normal, were studied through a total of 11 4-liter exchanges. Plasma was replaced by an equal volume of 5% albumin or 5% plasma protein fraction. Serial studies revealed that immediately after the exchange transfusion, there was significant prolongation of the prothrombin, partial thromboplastin, and thrombin times with reduction of the fibrinogen and antithrombin III levels. Factors V, VII-X, IX, and X were all significantly decreased, as were the factor VIII antigen, procoagulant, and the ristocetin cofactor activities. Platelet counts were obtained before and after exchanges and revealed significant decreases. Four hours after exchange, all parameters remained abnormal except the factor IX, ristocetin cofactor, and factor VIII procoagulant activities. By 24 hr, all hemostatic parameters had returned to normal. These studies indicate that plasma-exchange transfusion with material devoid of coagulation factors results in a coagulation defect that may be of clinical significance in a hemostatically compromised patient.
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PMID:The hemostatic imbalance of plasma-exchange transfusion. 46 36

The precise quantitation of activated factors in human factor IX concentrates has been accomplished with the use of recently developed, specific assays for factors IXa, Xa, and thrombin. The assay for factor IXa, which measures the initial rate of 3H-factor-X activation, was shown to be specific for factor IXa in the concentrates. Activated factor IX concentrates contained 1.0-2.3 microgram/ml of factor IXa; whereas the assays of unactivated concentrates were negative (less than 0.2 microgram/ml). The assays of factor Xa and thrombin, which measure the initial rate of p-nitroaniline release from S-2222 and S-2238, respectively, showed similar small amounts of factor Xa (4-34 ng/ml) and thrombin (12-76 ng/ml) in the activated and unactivated concentrates. The nonactivated partial thromboplastin time of the concentrates correlated significantly with the factor IXa content, but not with factor Xa or thrombin. Antithrombin III antigen in 3 of 4 concentrates was several-fold higher than antithrombin III activity, suggesting the presence of antithrombin III complexed with activated factors. These results support the hypothesis that the degree of activation of factor IX concentrates is related primarily to the concentration of factor IXa, which may be responsible for the thrombogenicity of these concentrates in some clinical settings.
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PMID:Activated clotting factors in factor IX concentrates. 49 95

The effect of collagen on isolated platelets, platelet-rich plasma and whole blood has been studied. Collagen failed to generate factor XIa-like activity in mixtures of isolated platelets, collagen and Ca++. Moreover, collagen added to whole blood or platelet-rich plasma containing 125I-factor IX and Ca++, also failed to form cleaved (activated) factor IX. In preliminary studies, lysed endothelial cells were found to enhance the formation of factor Xa and thrombin and to induce cleavage of 125I-factor IX in normal plasma, factor XII and factor-XI-deficient plasma even in the presence of antibody to tissue factor.
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PMID:The role of endothelial cells and subendothelial components in the initiation of blood coagulation. 51 Oct 12

Thrombogenicity of the factor IX concentrate and its clinical use for stoppage of the bleeding in the case of hemophilia A with inhibitor were reported. (1) Factor IX concentrate contained the coagulation factors as prothrombin complex (factors II, VII, IX and X); Thrombin and factor Xa. (2) Prothrombin in the factor IX concentrate could be converted to thrombin without any additional procoagulant such as thromboplastin or factor V, but in just 2.5M glycine solution by the effect of factor Xa. (3) The infusion of factor IX concentrate into a rabbit induced DIC promptly which was proved by autopsy and coagulation-fibrinolytic studies. (4) Factor IX concentrate showed a great efficacy in stopping the bleeding in the case of hemophilia A with inhibitor.
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PMID:Characteristics and thrombogenicity of factor IX concentrate. 61 88

Factor IX concentrate was obtained using DEAE-Sephadex A-50 as an adsorbent. The yield of factor IX in vitro averaged 81%. Each bottle of the concentrate contained 288-512 u. of factor II, 96--360 u. of factor VII, 440--660 u. of factor IX and 256--680 u. of factor X. The results of studies showed trace amounts of factor Xa in the final product, in the range of 0.01--0.04 u/ml. The concentrate was found to be free of thrombin. In the years 1976--1977 the new concentrate was administered 48 times to 10 patients with severe haemophilia B. The in vivo recovery of factor IX was 27--65%. Clinical results of treatment were satisfactory in all patients. No significant changes were observed in platelet count, fibrinogen level and the concentration of fibrinogen degradation products after infusion of the concentrate. The ethanol gelation test was negative in all cases.
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PMID:[Preparation and clinical use of a new factor IX concentrate]. 66 30

We studied the activation of factor X by the intrinsic pathway of blood coagulation using a new assay of factor X activation. When factor X tritiated in its sialic acid residues is activated, activation can be measured by the release of tritiated activation peptide, and the initial rate of activation can be determined under varying conditions. In the presence of phospholipid and calcium ions, factor IXa activated factor X slowly without factor VIII, and this activation was blocked by a specific factor IX inhibitor. These data provide strong evidence that factor IXa is the enzyme responsible for factor X activation by the intrinsic pathway. The role of factor VIII was also investigated. Factor VIII could be reproducibly thrombin activated and then stabilized by the addition of 2 mM benzamidine hydrochloride; this suggests that inactivation is due to proteolysis. Neither unactivated nor thrombin-activated factor VIII produced factor X activation without factor IXa. With a constant level of factor IXa, factor X activation was directly proportional to the level of activated factor VIII. With a constant level of activated factor VIII, factor X activation was proportional to the factor IXa concentration. This observation was exploited to develop a specific, sensitive assay for factor IXa.
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PMID:Activation of factor X by factors IXa and VIII; a specific assay for factor IXa in the presence of thrombin-activated factor VIII. 69 98

Nine patients with severe classic hemophilia and inhibitors against factor VIII were treated for 156 bleeding episodes with 503 infusions of Proplex, Konyne, or Auto-Factor IX, three preparations of prothrombin complex concentrates (PCCs). Approximately two thirds of the bleeding episodes were managed successfully. Although the prothrombin time (PT) and partial thromboplastin time (PTT) were shortened after most PCC infusions, there was no evidence of disseminated intravascular coagulation. The degree of shortening of PT or PTT was not related to the particular PCC preparation used, dose, or cessation of hemorrhage. All PCC preparations contained activated clotting factors, as manifested by their ability to shorten the PTT of normal plasma, factor-VIII-deficient plasma, and factor-IX-deficient plasma. Shortening, which was greater with Auto-Factor IX than with the other products, was inhibited partially by a factor IX antibody and blocked completely by prolonged incubation with plasma. Although the nature of the procoagulant material in PCCs is uncertain, these products are of proven benefit to hemophilic patients with high-titer inhibitors. Side effects have been minimal and inhibitor titers have not risen.
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PMID:Use of prothrombin complex concentrates in hemophiliacs with inhibitors: clinical and laboratory studies. 72 19


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