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

---

Query: EC:3.4.21.6 (thromboplastin)
13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Factor VIII (antihemophilic factor) is the protein that is deficient or defective in patients with classical hemophilia and Von Willebrand syndrome. Factor VIII in plasma is thought to be associated in a complex with the highest molecular weight multimers of another glycoprotein, Von Willebrand protein. Highly purified human factor VIII appears to have an Mr of between 200,000 and 300,000 and to consist of several polypeptide chains. The concentration of factor VIII in plasma is around 100-200 ng/ml, equivalent to around 1 nM. The purified proteins retain one or more of the known properties of factor VIII, including the acceleration of factor IXa-mediated activation of factor X, ability to be activated by thrombin and factor Xa, inactivation by activated protein C, and by human antibodies to factor VIII. Among the known clotting factors, factors VIII and V are exceptional in not possessing enzymatic activity. Factors IXa and VIII and X appear to form a functional complex, all of which need to be present and active simultaneously for optimal activation of factor X. The mechanism by which factor VIII promotes activation of factor X by factor IXa is not known, but the major effect is to increase the rate of the reaction. Following treatment of factor VIII with thrombin, a new and smaller polypeptide Mr around 70,000 +/- 5,000 is produced. Factors IXa and Xa also have been reported to activate factor VIII. It is not known whether limited proteolytic cleavage is required absolutely for the expression of factor VIII activity or if it only increases an activity already expressed by the uncleaved protein. Factor VIII is inactivated by thrombin and by activated protein C. Thus, factor VIII can be modulated by at least four of the serine proteases in the clotting system. A major goal for future research is to increase our understanding of the role in blood clotting played by factor VIII, and to apply this information to clinical problems which result from inherited abnormalities of factor VIII.
...
PMID:Factor VIII: structure and function in blood clotting. 642 37

Major surgical procedures are now performed with acceptable risk on patients with hemophilia A with pre- and postoperative anti-hemopilic Factor (AHF) infusions. However, there is almost no literature on care of the burned hemophiliac. We recently treated a patient with Factor VIII levels of less than 2% of normal and 45% TBSA burns. A forearm escharotomy was done with hemostatic protection by AHF infusion, but burn therapy, which included operative debridement and successful split-thickness skin grafting, was accomplished without the use of AHF. It is concluded that after early loading with cryoprecipitate, burned hemophiliacs do not require continued AHF, because repair and restoration of vascular integrity in small vessels may occur due to platelet plugging and vessel retraction. Tissue thromboplastin may also contribute to clotting in burned hemophiliacs.
...
PMID:The burned hemophiliac. 677 99

Bovine factor VIII, which did not contain platelet aggregating factor activity, was infused into hemophilic dogs. Factor VIII procoagulant (VIII:C) levels in the dogs increased dramatically, then decreased in a biphasic manner. The half-life of the longest component was 3-7 hrs. The infusions were hemostatically effective and also caused a prolonged shortening of the activated partial thromboplastin time. These studies demonstrate that the platelet aggregating factor activity of bovine factor VIII is not essential for its maintenance in the circulation and that preparations lacking this activity may be clinically useful. When concentrates of partially purified factor VIII: C (essentially free of both platelet aggregating factor and factor VIII-related antigen) were infused, marked increases in VIII: C levels were also observed, but the half-life was significantly shorter (T1/2 of approximately 1 hr.).
...
PMID:Kinetic analysis of bovine factor VIII in the hemophilic dog. 679 39

The introduction of the activated partial thromboplastin time (APTT) as a screening test has resulted in increased recognition of circulating anticoagulants. The most frequently encountered inhibitor is the lupus-type anticoagulant. However, criteria for differentiation of this inhibitor are not well-established. We evaluated the ability of two procedures, tissue thromboplastin inhibition (TTI) and a new platelet neutralization procedure (PNP), to differentiate between various types of coagulation inhibitors. The TTI, widely used for the diagnosis of lupus anticoagulants, proved to be nonspecific. The PNP specifically separated lupus-type inhibitors from Factor VIII, X, and V inhibitors. The PNP may be a useful test for the diagnosis of lupus anticoagulants.
...
PMID:Laboratory diagnosis of lupus inhibitors: a comparison of the tissue thromboplastin inhibition procedure with a new platelet neutralization procedure. 684 58

In coagulation tests on five lowland gorillas, values within or close to the normal human range were found with the following tests: partial thromboplastin time, prothrombin time, thrombin time, factor XIII screen, factor II assay, factor V assay, fibrinogen and antithrombin III. Factor XII levels were very high. Factor VIII coagulant activity was moderately elevated but factor VIII antigen was very high in all and ristocetin cofactor activity was low in four of five.
...
PMID:Blood coagulation tests of gorillas. 712 Mar 59

An analysis was made of 41 cases of disseminated intravascular coagulation in dogs, with the objective of evaluating routine and nonroutine laboratory tests used in making the diagnosis. The dogs were grouped on the basis of underlying disease, which included neoplasia (39%), pancreatitis (30%), chronic active hepatitis (15%), heat stroke (12%), and sepsis (4%). Of the diagnostic tests evaluated, those for determination of activated partial thromboplastin time, antithrombin III activity, prothrombin time, and the platelet count were the most valuable. Of the clotting factors, factor V activity was decreased more frequently than the activity of factor VIII:C (factor VIII: procoagulant). The factor VIII:C activity was in conflict with prevailing dogma that reflects depression of this factor in disseminated intravascular coagulation. Factor VIII:C activity was decreased in only 29% of dogs studied. Activation of the fibrinolytic system was manifested by decreased plasminogen activity in 49% of the dogs studied. Sixty-one percent of the dogs had increased amounts of fibrin (ogen) degradation products.
...
PMID:Disseminated intravascular coagulation: antithrombin, plasminogen, and coagulation abnormalities in 41 dogs. 726 67

Factor VIII has been purified approximately 300000-fold from bovine plasma by ammonium sulfate fractionation, glycine precipitation, DEAE-Sephadex column chromatography, sulfate--Sepharose column chromatography, Sephadex G-200 gel filtration, and factor X--Sepharose column chromatography. The highly purified preparation migrated as a triplet on sodium dodecyl sulfate/urea--polyacrylamide gel electrophoresis with apparent molecular weights of 93000, 88000, and 85000. The coagulant activity of the purified preparations was inhibited by antibodies raised in rabbits against either the purified factor VIII protein or a preparation of factor VIII/von Willebrand factor. Antibodies to the purified protein also inhibited the coagulant activity of factor VIII/von Willebrand factor preparations. The purified factor VIII contained no platelet-aggregating activity, as measured in human platelet-rich plasma. The purified preparation of factor VIII was required for the activation of factor X in the presence of factor IXa, calcium, and phospholipid. It was activated about 30-fold by thrombin or factor Xa plus calcium and phospholipid, and each of these reactions was accompanied by a change in the sodium dodecyl sulfate/urea--polyacrylamide gel electrophoresis pattern of the protein. Factor VIII was rapidly inactivated by bovine-activated protein C in a reaction requiring calcium and phospholipid. This reaction was also associated with a change in the sodium dodecyl sulfate/urea--polyacrylamide gel electrophoresis pattern of the highly purified protein. These experiments involving three highly specific serine proteases support the conclusion that the triplet observed on polyacrylamide gels is factor VIII.
...
PMID:Preparation and properties of bovine factor VIII (antihemophilic factor). 735 33

A 81-year-old man who had been healthy without any history of abnormal bleeding, developed ecchymosis and hematuria in November, 1992 and was hospitalized in December, 1992. On admission, he developed widespread ecchymosis in his trunk and extremities, and subsequently ecchymosis of his cheek and neck, and also oral and pharyngeal hematoma. The laboratory data were as follows: whole blood clotting time, > 20 minutes; activated partial thromboplastin time (APTT), 108.6 seconds; Factor VIII activity, 4%. The level of Factor VIII inhibitor was high, 65.0 Bethesda Unit/ml. This inhibitor was a IgG type immunoglobulin, which had both kappa and lambda light chain. His serological and blood biochemical data of the blood were normal, and tests for autoantibodies were negative. The patient was treated with plasma exchange therapy, Prednisolone (PSL), Cyclophosphamide and Factor VIII concentrate. The hemorrhagic symptoms were improved, the inhibitor disappeared and the activity of Factor VIII returned to normal after one month. Follow-up was continued in the outpatient clinic for 5 months. After the dose of PSL was decreased, he developed bloody sputum and hematuria, and was readmitted in August, 1994. Factor VIII activity was 21% and the titer of Factor VIII inhibitor was 3.0 BU/ml. The hemorrhagic symptoms disappeared soon after increasing the dose of PSL, and the Factor VIII activity was normalized and the inhibitor could not be detected. These treatments appeared to offer effective control on severe hemorrhage in a patient with Factor VIII inhibitor.
...
PMID:[Elderly non-hemophiliac patient with factor VIII inhibitor presenting various type hemorrhages]. 773 44

The effect of insulin-induced hypoglycaemia on plasma coagulant activity was studied in 11 subjects with well-controlled, uncomplicated type 1 diabetes. Thrombin generation was determined in plasma by a computer ex-vivo assisted chromogenic method and by the activated partial thromboplastin time (APTT). In addition, factor VIII:C, thrombin-antithrombin III (TAT) complex and fibrinopeptide A (FPA) levels were measured. Hypoglycaemia induced a rise in mean (SD) factor VIII:C concentrations from a baseline level of 1.13 (0.32) IU/ml to a peak 15 min after onset of symptoms and they remained increased at 90 min [1.54 (0.57) and 1.5 (0.54) IU/ml, p < 0.001 respectively]. A corresponding reduction in time to generate 50% maximal thrombin activity occurred from a pre-insulin value of 56 (6) s to a minimum reading of 46 (7) s at 15 min (p < 0.001) and remained low at 90 min [48 (6) s, p < 0.001]. APTT shortened from 43.3 (4.8) s to 40.1 (4.6) s at 30 min (p < 0.001) but did not fall below the normal range (37.6-42.7 s) and no significant changes in TAT or FPA levels were noted. Factor VIII:C correlated inversely with time to generate 50% maximal thrombin activity and APTT (r = -0.580, p < 0.001; r = -0.673, p < 0.001, n = 66, respectively). The results show that the rise in plasma factor VIII:C levels induced by hypoglycaemia is accompanied by accelerated rates of generation of thrombin in contact-activated plasma, though concentrations of FPA and TAT remain unchanged, although TAT complexes are not a sensitive marker of in vivo thrombin generation.
...
PMID:The effect of insulin-induced hypoglycaemia on factor VIII:C concentrations and thrombin activity in subjects with type 1 (insulin-dependent) diabetes. 779 37

This study evaluated the haemostatic profiles of a group of 11 female and seven male calves from the day of birth until they were 60 days of age. Similar results were found for both sexes. At birth the plasma activity of the procoagulant proteins, Factors VII, VIII:C, IX, X and XI and fibrinogen were all close to the adult values. Factors VII, VIII:C and fibriogen increased transiently during the first seven days of life but the increases were not sufficient to influence routine coagulation screening assays such as the activated partial thromboplastin time and the prothrombin time. At birth, the plasma concentration of the protease inhibitor, alpha 2-macroglobulin, was approximately 50 per cent of adult values and increased slowly during the first seven days of life; the plasma concentration of antithrombin III was higher than that of alpha 2-macroglobulin. The changes in the plasma concentration of fibronectin paralleled the changes in fibrinogen and Factor VIII:C from birth to 60 days of age; the concentrations of total plasma protein and plasma albumin remained stable and within the adult ranges throughout the 60 days. The plasma concentration of glucose increased transiently during the first 48 hours after birth.
...
PMID:Competency of blood coagulation in the newborn calf. 787 Dec 54


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---