Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0684275 (haemophilia)
 10,958 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Asymptomatic hemophilia patients receiving Factor VIII concentrate were found to have normal natural killer (NK) cells and B cells, and an inverted T helper/suppressor ratio due to an increase in cells of T suppressor phenotype. In contrast, a hemophilia patient with acquired immune deficiency syndrome (AIDS) exhibited nonfunctional NK cells, low B cells, and an inverted T helper/suppressor ratio due to very low numbers of T helper cells. Hemophilia patients on cryoprecipitate therapy exhibited normal immune parameters. A high percentage of hemophilia patients on both treatments had antibody to hepatitis B virus. The isolated finding of elevated levels of T suppressor cells in hemophilia patients receiving Factor VIII concentrate has not been recognized as an early indicator of impending AIDS, and longitudinal studies will be required to determine its clinical significance.
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PMID:Immunologic studies in asymptomatic hemophilia patients. Relationship to acquired immune deficiency syndrome (AIDS). 622 70

Scottish patients with haemophilia, most of whom had received no American factor VIII concentrate for over two years, were found to have immunological abnormalities similar to those in their American counterparts--that is, a reduced proportion of T helper cells, an increased proportion of T suppressor cells, and a reduced response to concanavilin A. Factor VIII from both the United States and Scotland severely inhibited the in vitro lymphocyte response to mitogens in patients and controls. The American and Scottish concentrates could not be distinguished in terms of either patient usage or their effect in vitro. These results argue against a disease vector specific to American blood products.
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PMID:Immunological abnormalities in haemophilia: are they caused by American factor VIII concentrate? 622 34

Blood interaction with the subendothelium of rabbit aorta was investigated in an annular perfusion chamber using patients with von Willebrand's disease, hemophilia, and afibrinogenemia. The vessels were exposed to nonanticoagulated blood for a range of flow conditions (wall shear rates of 650-3,300 s-1) and exposure times (1.5-10 min). The resultant platelet and fibrin interaction was quantified by the use of several morphometric techniques, one of which was developed to measure more precisely the dimensions (height and volume) of platelet thrombi attached to the subendothelium. A major finding was that under flow conditions in which little or no defect in platelet adhesion was observed in von Willebrand's disease, platelet thrombus height and volume in this disorder were significantly reduced as compared with normal controls or patients with hemophilia. Thus, Factor VIII/von Willebrand factor (VIII/VWF) may mediate not only the adhesion of platelets to subendothelium but also platelet-platelet attachments necessary for normal thrombus development. The level of Factor VIII:coagulant activity (VIII: C) was also observed to influence the resultant thrombus height and volume deposited on subendothelium, presumably through the generation of thrombin or some other procoagulant factor preceding fibrin formation, since normal values of thrombus dimensions were always observed in a patient with a fibrinogen deficiency. The influence of VIII:C became greater as shear rate was reduced, whereas as shear rate was increased, VIII/VWF was more dominant in determining the resultant platelet deposition on subendothelium. Thus, the deficiencies of VIII:C and VIII/VWF in hemophilia and von Willebrand's disease can lead to various abnormalities in platelet and fibrin association with subendothelium. The importance of a particular deficiency will depend strongly on the local blood flow conditions.
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PMID:Platelet interaction with rabbit subendothelium in von Willebrand's disease: altered thrombus formation distinct from defective platelet adhesion. 633 2

Factor VIII, a high molecular weight glycoprotein complex which has an important role in haemostasis, consists of two immunologically as well as functionally discernible moieties that can be isolated separately. These are factor VIII/von Willebrand factor (FVIII/vWF) which is associated with the factor VIII-related antigen (FVIIIRAg), and the factor VIII/procoagulant activity (FVIII/C) which is associated with the factor VIII/procoagulant antigen (FVIII/CAg). The FVIII/C activity is decreased or absent in patients with haemophilia A (for a review of the structure and function of the factor VIII complex, see refs 1 and 2). Immunological techniques, combined with cell culture, have demonstrated that FVIIIRAg is present in and synthesized by endothelial cells and megakaryocytes. However, the organ and/or cell type responsible for the production of FVIII/C has not been established. Indirect evidence derived from organ transplantation in experimental animals suggests that the liver is the most likely organ for FVIII/C production. Here we have used a monoclonal antibody against FVIII/CAg in combination with a sensitive immunostaining technique to demonstrate the presence of FVIII/CAg in hepatic sinusoidal endothelial cells.
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PMID:Detection of factor VIII/coagulant antigen in human liver tissue. 640 6

For the purposes of prenatal diagnosis and carrier detection of haemophilia A, an enzyme linked immunosorbent assay (ELISA) was developed for the quantitation of plasma Factor VIII coagulant antigen (VIII:CAg). It is based upon a human antibody. Results are compared to assays for Factor VIII coagulant activity (VIII:C) and Factor VIII related antigen (VIIIR:Ag) in plasma from 30 normal female individuals, 5 fetuses from mothers normal with respect to bleeding status, 10 obligate carriers of haemophilia A, 10 patients with haemophilia A, 5 with von Willebrand's disease, and 5 with haemophilia B. The ELISA developed is simpler than previously published VIII:CAg methods owing to its use of total IgG instead of immunologically affinity-purified antibodies. It is specific (as judged from clinical results), sensitive (detection limit: 0.005 units/ml), and sufficiently precise (between-assay coefficient of variation: 11%) for the purposes mentioned. The coefficient of correlation between VIII:CAg and VIII:C results is 0.86. The introduction of ELISA for quantitating VIII:CAg represents an advantage as compared to existing immunoradiometric assays (IRMA) mainly due to the stable and non-radioactive reagents used in the ELISA.
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PMID:An enzyme immunoassay (ELISA) for the quantitation of human factor VIII coagulant antigen (VIII:CAg). 641 26

The ratio of factor VIII coagulant activity (VIIIC) or antigen (VIIICAg) to that of factor VIII related antigen (VIIIRAg) was measured in 15 normals, 21 obligatory and 23 possible carriers of hemophilia. Factor VIII coagulant was measured on fresh plasma samples whereas antigenic properties were measured on frozen and thawed samples. In obligatory carriers only, the mean level of VIIICAg was significantly lower than VIIIC and there was a tendency for low VIIICAg levels to be associated with raised VIIIRAg levels. Using both ratios, 13 obligatory carriers were outside the normal tolerance ellipse. In possible carriers, neither ratio showed superior discriminating power. In reference laboratories that perform carrier studies on stored or transported specimens, measurement of VIIICAg/VIIIRAg is a suitable test for diagnosis of carriers.
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PMID:A comparison of "carrier screening" of hemophilia by the ratio of factor VIII coagulant activity or antigen to factor VIII related antigen. 641 26

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.
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PMID:Factor VIII: structure and function in blood clotting. 642 37

World-wide use of large amounts of highly purified Factor VIII and Factor IX concentrates has increased steadily over the last decade. The increase has resulted in more effective treatment of patients with haemophilia, especially those patients on home care and 'demand' therapy, those on prophylactic therapy for chronic bleeding or those on maintenance therapy for the suppression of inhibitors. Changing socioeconomic conditions have also contributed to greater use of the concentrates. The trend is putting an increasing strain on conventional methods for collecting and fractionating plasma. These include the donor, the nature of the anticoagulant, methods for purification of the clotting factors, procedures for denaturation and/or separation of viral contaminants and patterns of clinical usage. As a result, it is essential that we upgrade the quantity and quality of plasma collected and utilize the most effective new methods for increasing the yield and purity of the plasma fractions. Of special significance are recently described procedures for heat inactivation and/or separation of viral contaminants from the fractions and the long-term promise of genetically engineered proteins.
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PMID:Approaches to plasma fractionation for improved recovery and the development of potentially useful clinical factors. 642 34

We studied immune function in Belgian haemophiliacs treated with Factor VIII from volunteer donors. No patient had clinical evidence of immune deficiency. We found a decrease in T-helper cells (p less than 0.0005), in the ratio of T-helper over T-cytotoxic/suppressor cells (1.72 +/- 0.47 versus 2.24 +/- 0.82 in controls, p less than 0.005) and in lymphocyte responsiveness to mitogens (p less than 0.05). These findings could not be linked to the amount of F VIII received over the last year, the time since last F VIII administration, circulating immune complexes (54% positive patients, 7% positive controls, p less than 0.005), increased ALT levels, antibodies to cytomegalo -virus (85% of the patients, 45% of the controls, p less than 0.005), antibodies to Epstein-Barr virus, nor to the presence of HLA-DR 5 which was found in 56% of the haemophiliacs (20% of the overall Belgian population, p less than 0.005). Either F VIII induces long lasting immunological alterations unrelated to AIDS, or haemophilia is itself associated with such changes.
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PMID:Immunological alterations in haemophiliacs treated with lyophilized Factor VIII cryoprecipitate from volunteer donors. 642 83

During a 4-year national cooperative study of factor VIII inhibitors in patients with classic hemophilia, new inhibitors were identified in 31 of 1,306 patients without this finding on entry. The age of patients upon detection of an inhibitor ranged from 2-62 years with a median age of 16 years. The incidence of new inhibitors was 8 per 1000 patient-years of observation. In 29 patients baseline VIII:C was less than or equal to 0.03 units/ml; the other two patients had levels of 0.06 and 0.07 units/ml. Factor VIII:CAg was measured in entry samples of plasma from 27 subjects and generally corresponded to levels of VIII:C; the levels of VIII:CAg ranged from 0.01-0.11 units/ml in 9 cases and were less than 0.01 units/ml in the remaining 18. In no instance did an inhibitor develop without preceding exposure to infused VIII:C, appearing within 8-250 VIII:C exposure-days in all patients and within 75 exposure-days in 10 of 11 patients with maximum inhibitor values greater than 15 Bethesda units/ml. Development of an inhibitor could not be correlated with any of the following variables: bleeding tendency, intercurrent illness, drugs, and selected clinical laboratory tests including blood counts, liver enzymes, and immunoglobulins. On the basis of maximum activity and persistence of inhibitors, a spectrum of patterns could be identified. (1) In Group IA with 9 patients, inhibitors with maximum values greater than 15 Bethesda units/ml persisted throughout the remaining study period. (2) In Group IB with 2 patients with mild classic hemophilia, inhibitors with maximum values greater than 15 Bethesda units/ml disappeared despite varying continued exposure to VIII:C and PCC. (3) In Group IIA with 10 patients, inhibitors with maximum values less than or equal to 15 Bethesda units/ml persisted throughout the remaining study period. (4) In Group IIB with 3 patients, maximum values less than or equal to 15 Bethesda units/ml disappeared within 18 months despite varying continued exposure to VIII:C and PCC. (5) In Group III with 7 patients, an inhibitor with a value of less than 5 Bethesda units/ml was conclusively documented on a sing study period. (4) In Group IIB with 3 patients, maximum values less than or equal to 15 Bethesda units/ml disappeared within 18 months despite varying continued exposure to VIII:C and PCC. (5) In Group III with 7 patients, an inhibitor with a value of less than 5 Bethesda units/ml was conclusively documented on a sing study period.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Clinical patterns of hemophilic patients who develop inhibitors. 643 36


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