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)

Although DDAVP has been shown to be haemostatically efficacious in patients with various congenital or acquired platelet disorders, no reasonable explanation has been found for this effect. We have previously shown DDAVP to increase platelet adhesiveness as measured with a platelet retention test. The aim of the present study was to investigate the mechanism of action responsible for the increased platelet retention in response to DDAVP. Patients with vWD type III and type Ia, severe haemophilia and severe thrombasthenia, as well as healthy controls, were included in the study. The effect of different concentrations of vWF in plasma and platelets was explored, as was the effect on platelet function of apyrase and monoclonal antibodies against GP IIb/IIIa and GP Ib. We found the effect of DDAVP on platelet retention to be unaffected by changes in the plasma concentration of vWF. The enhanced platelet retention after DDAVP is apparently dependent on the presence of platelet-vWF and on a normal function of the GP IIb/IIIa. The effect is not mediated via ADP or thrombin. The platelet-stimulating effect of DDAVP may be one explanation for the positive haemostatic effect in patients with certain platelet disorders.
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PMID:DDAVP-induced enhancement of platelet retention: its dependence on platelet-von Willebrand factor and the platelet receptor GP IIb/IIIa. 149 98

We have studied the conditions of in vitro binding of platelet glycoprotein IIb/IIIa (GPIIb/IIIa) to fibrinogen and applied the results to identify and measure the serum inhibitors to the binding. For the enzyme-linked immunosorbent assay, platelet extract was delivered to a fibrinogen-coated microtiter plate that was incubated for 2 hours, followed by incubation with anti-GPIIb/IIIa monoclonal antibody for another 2 hours. The plate was then incubated with peroxidase-conjugated anti-mouse IgG for color development. The binding was shown to be calcium-dependent. The binding was partially blocked by treating the coated fibrinogen with anti-fibrinogen antibody. Reduction or dissociation of GPIIb/IIIa resulted in the total loss of its ability to bind to fibrinogen. Platelet extracts of patients with hemophilia showed decreased binding (25% and 14%, compared with control platelet extract), and an extract from a patient with Glanzmann's thrombasthenia showed no binding. With the enzyme-linked immunosorbent assay we have measured serum inhibitors to GPIIb/IIIa binding to fibrinogen in 35 hemophilia A, 17 immune thrombocytopenic purpura, 22 human immunodeficiency virus-related immune thrombocytopenic purpura, and 29 systemic lupus erythematosus serum samples. In those patients with inhibition by serum, polyethylene glycol precipitation of circulating immune complexes (CICs) decreased the inhibition by the supernatants, and all the resolubilized CIC precipitates demonstrated inhibition, which indicates that CICs play a major role in the inhibition of GPIIb/IIIa binding to fibrinogen. This, then, provides evidence of CIC-mediated impaired GPIIb/IIIa binding to fibrinogen in hemophilia A, HIV-ITP, and SLE.
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PMID:Inhibition of platelet GPIIb/IIIa binding to fibrinogen by serum factors: studies of circulating immune complexes and platelet antibodies in patients with hemophilia, immune thrombocytopenic purpura, human immunodeficiency virus-related immune thrombocytopenic purpura, and systemic lupus erythematosus. 200 77

The structural and functional studies of the concentrate of von Willebrand factor (vWF) manufactured by LFB have been first performed as part of the preclinical development of this product specially intended for the treatment of von Willebrand disease. The electrophoretic analyses showed the high purity of LFB-vWF concentrate (specific activity of 100 IU of ristocetin cofactor activity per milligram of protein) and the multimeric pattern attesting the presence of high molecular weight multimeters (> or = 15-mers). The measurements of vWF capacity to bind to: (1) platelet glycoprotein (GP) Ib in the presence of ristocetin; (2) GPIIb/IIIa in the presence of thrombin; (3) types I and III collagen; (4) factor VIII (FVIII) gave evidence that the functional activity of purified vWF was similar to that of native plasma vWF. Furthermore the LFB-vWF concentrate was able to promote platelet adhesion to collagen. The release of the therapeutic batches of this product rely presently on their potency measured with the ristocetin cofactor activity (40-70 IU ml-1) and the quantitative evaluation of vWF multimeric distribution studied using electrophoresis in 1.5% agarose. These validated techniques ensure the consistency and haemostatic properties of the different lots of LFB-vWF concentrate.
Haemophilia 1998
PMID:In vitro evaluation of the haemostatic value of the LFB-von Willebrand factor concentrate. 1002 17

Cardiovascular and cerebrovascular diseases continue to be the leading cause of death throughout the world. Over the past two decades, great advances have been made in the pharmacological treatment and prevention of thrombotic disorders (e.g., tissue plasminogen activators, platelet GPIIb/IIIa antagonists, ADP receptor antagonists such as clopidogrel, low-molecular weight heparins, and direct thrombin inhibitors). New research is leading to the next generation of antithrombotic compounds such as direct coagulation FVIIa inhibitors, tissue factor pathway inhibitors, gene therapy, and orally active direct thrombin inhibitors and coagulation Factor Xa (FXa) inhibitors. Animal models of thrombosis have played a crucial role in discovering and validiting novel drug targets, selecting new agents for clinical evaluation, and providing dosing and safety information for clinical trials. In addition, these models have provided valuable information regarding the mechanisms of these new agents and the interactions between antithrombotic agents that work by different mechanisms. This review briefly presents the pivitol preclinical studies that led to the development of drugs that have proven to be effective clinicallly. The role that animal models of thrombosis are playing in the discovery and development of novel antithrombotic agents is also described, with specific emphasis on FXa inhibitors. The major issues regarding the use of animal models of thrombosis, such as the use of positive controls, appropriate pharmacodynamic markers of activity, safety evaluation, species-specificity, and pharmacokinetics, are highlighted. Finally, the use of genetic models in thrombosis/hemostasis research and pharmacology is presented using gene-therapy for hemophilia as an example of how animal models have aided in the development of these therapies that are now being evaluated clinically. In summary, animal models have contributed greatly to the discovery of currently available antithrombotic agents and will play a primary role in the discovery and characterization of the novel antithrombotic agents that will provide safe and effective pharmacological treatment for life-threatening thrombotic diseases.
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PMID:Contribution of in vivo models of thrombosis to the discovery and development of novel antithrombotic agents. 1115 Jul 38

Severe haemophilia is a serious, haemorrhagic disorder of the plasmatic coagulation system. In this study we investigated, whether 'compensatory' activation of the platelet coagulation system occurs in this situation. Platelet function was investigated with aggregation, adhesion and flow cytometric assays. In addition, we performed clot and platelet plug formation tests and determined endogenous thrombin potentials in patients with severe haemophilia A or B; results were compared to those of healthy controls. Platelet aggregation in response to stimulation with ADP, ristocetin and epinephrine was similar in patients and controls; aggregation in response to collagen was reduced significantly in haemophiliacs. Flow cytometric analysis of P-selectin (CD 62P) and CD 63, of the conformationally changed GP IIb/IIIa with PAC 1 and of thrombospondin bound to CD 36 (GP IV) was performed at baseline and post stimulation. Baseline expression of all markers was similar in haemophiliacs and controls. After stimulation of the platelet thrombin receptors with the thrombin receptor activating peptide (TRAP) 6, the surface expression of all markers increased significantly; again, the expression was similar in haemophiliacs and controls. With thrombelastography and PFA 100 analysis, clot formation under low shear and platelet plug formation under high shear is measured. Both test results revealed a significantly reduced clot and platelet plug formation capacity in severe haemophiliacs. Our results did not reveal signs of enhanced platelet preactivation in haemophiliacs, indicating that baseline platelet reactivity in severe haemophilia remains in a neutral state, despite the severely haemorrhagic condition. As expected, both thrombin and clot formation capacities were impaired significantly in severe haemophilia. The reduced response to collagen-based platelet stimulation tests is indicative of a concomitant platelet function defect. This defect probably contributes to the intensity of bleeding events in patients with severe haemophilia.
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PMID:Absence of compensatory platelet activation in patients with severe haemophilia, but evidence for a platelet collagen-activation defect. 1248 78

Haemophilia A is an attractive target for gene therapy. We designed a haemophilia A gene therapy strategy involving the genetic modification of haematopoietic stem cells to achieve tissue-specific expression of a factor VIII (FVIII) transgene in the megakaryocytic lineage. Platelets would then serve as vehicles to store the expressed FVIII and deliver the coagulation factor at the site of vascular injury. A local correction of the haemostasis defect could, therefore, be expected following platelet activation and secretion. In this study, we demonstrated that a model of haematopoietic cell lines (Dami cells) could produce a correctly processed FVIII. FVIII transgenes were placed under the control of the human platelet glycoprotein IIb (GPIIb) promoter and used for stable transfection of the Dami megakaryocytic cell line. The highest FVIII production was obtained when the FVIII transgene contained a factor IX intron 1 gene sequence inserted in the FVIII intron 1 and 13 sites. Reverse transcription polymerase chain reaction demonstrated that the splicing of these introns was complete. Recombinant FVIII (rFVIII) produced in Dami cells was a biologically active molecule (specific activity: 5664 IU/mg) that was correctly glycosylated and sulphated. This recombinant FVIII protein exhibited biochemical characteristics after deglycosylation or thrombin activation that were comparable to a commercially available B-domainless rFVIII. These results demonstrate the advantages of a modified FVIII transgene and represent the first biochemical characterization of megakaryocyte-produced FVIII.
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PMID:Biosynthesis of FVIII in megakaryocytic cells: improved production and biochemical characterization. 1556 60

Glanzmann thrombasthenia (GT) is a rare platelet function disorder characterized by a defect in fibrinogen binding to platelet membrane glycoprotein (GP) IIb/IIIa. Recombinant FVIIa (rFVIIa) is a haemostatic agent approved for the treatment of haemophilia patients with inhibitors, patients with acquired haemophilia and in EU also for treatment of factor VII (FVII)-deficient patients and GT patients with antibodies to GPIIb-IIIa. The present study was conducted to evaluate the use of the whole blood test system, rotational thrombelastometry (ROTEM), in measuring the overall haemostasis potential of rFVIIa in 28 GT patients treated with rFVIIa. The correlation of administered rFVIIa and time to start fibrin formation and clot dynamic/stability was assessed and correlation to the clinical response was elucidated. Assessments were performed on predose blood samples spiked with four different concentrations of rFVIIa and whole blood samples taken at 10 and 120 min following dosing. ROTEM parameters clotting time (CT), clot formation time (CFT) and maximum clot firmness (MCF) were measured. Both ex vivo and in vivo data showed beneficial effects on CT in the presence of rFVIIa, but no effect of added rFVIIa was seen on CFT and MCF. In conclusion, the use of thrombelastography at least in the modified form of ROTEM seems to be of limited use in predicting an adequate dose of rFVIIa in GT patients. A good clinical haemostatic response was recorded in spite of the limited changes in the ROTEM pattern supporting the conclusion that ROTEM should not be the method of choice for monitoring rFVIIa therapy in Glanzmann patients.
Haemophilia 2008 Jan
PMID:Evaluation of rFVIIa (NovoSeven) in Glanzmann patients with thromboelastogram. 1807 65

Glanzmann Thrombasthenia (GT) is a rare autosomal recessive disorder which usually manifests as severe mucocutaneous bleeding and is caused by deficiency of the platelet glycoprotein IIb-IIIa. Pregnancy in women with GT presents particular challenges as there is increased risk of both maternal and foetal bleeding. To improve understanding and clarify the optimum management of pregnancy in this disorder, we performed a systematic review of the world literature of pregnancy and GT. This identified three single-centre case series of patients with GT that included brief descriptions of women in pregnancy and 31 detailed case reports of 40 pregnancies in 35 women that resulted in 38 live births. Among the detailed case reports, ante-natal bleeding was described in 50% of pregnancies but was usually mild and occurred at mucocutaneous sites. Primary postpartum haemorrhage (PPH) was reported in 34% of pregnancies and secondary PPH in 24%. PPH was frequently severe and occurred up to 20 days after delivery. There was a wide variation in approach to prevention and treatment of PPH but most women received platelet transfusion, sometimes with additional recombinant FVIIa and anti-fibrinolytics. Maternal alloimmunization against platelet antigens was reported in 73% of pregnancies and was associated with four neonatal deaths. These data emphasize the need for multidisciplinary management of pregnancy in women with GT. Delivery plans should recognize the need for prevention and aggressive treatment of PPH and should minimize foetal bleeding risk in pregnancies complicated by alloimmunization.
Haemophilia 2011 Sep
PMID:A systematic review of the management and outcomes of pregnancy in Glanzmann thrombasthenia. 2145 4

There are no evidence-based guidelines for antithrombotic management in people with haemophilia (PWH) presenting with acute coronary syndrome (ACS). The aim of the study was to review the current European Society of Cardiology guidelines, and to consider how best they should be adapted for PWH. Structured communication techniques based on a Delphi-like methodology were used to achieve expert consensus on key aspects of clinical management. The main final statements are as follows: (i) ACS and myocardial revascularization should be managed promptly by a multidisciplinary team that includes a haemophilia expert, (ii) each comprehensive care centre for adult PWH should have a formal clinical referral pathway with a cardiology centre with an emergency unit and 24 h availability of percutaneous coronary intervention (PCI), (iii) PCI should be performed as soon as possible under adequate clotting factor protection, (iv) bare metal stents are preferred to drug-eluting stents, (v) anticoagulants should only be used in PWH after replacement therapy, (vi) minimum trough levels should not fall below 5-15% in PWH on dual antiplatelet therapy, (vii) the duration of dual antiplatelet therapy after ACS and PCI should be limited to a minimum, (viii) the use of GPIIb-IIIa inhibitors is not recommended in PWH other than in exceptional circumstances, (ix) the use of fibrinolysis may be justified in PWH when primary PCI (within 90 min) is not available ideally under adequate clotting factor management. It is hoped that the results of this initiative will help to guide optimal management of ACS in PWH.
Haemophilia 2013 Nov
PMID:Applicability of the European Society of Cardiology guidelines on management of acute coronary syndromes to people with haemophilia - an assessment by the ADVANCE Working Group. 2371 May 76

Improvements in the management of haemophilia have led to a significant increase in the life expectancy of haemophilia patients, which is now close to the life expectancy in the general male population. Therefore, age-related conditions, especially cardiovascular disease (CVD), have become increasingly common in these patients. The management of CVD, especially that of coronary artery disease (CAD), acute coronary syndrome (ACS) and atrial fibrillation (AF), is particularly challenging in patients with haemophilia due to the need to find an adequate balance between bleeding and ischemic risk, requiring close coordination between cardiologists and haemophilia specialists. However, specific recommendations and relevant literature and data are scarce. Therefore, we propose pragmatic and practical therapeutic suggestions, based on the available literature and our own experience, for the management of ACS, stable angina and AF in patients with haemophilia. Overall, evidence and experience suggest that they should be treated much in the same way as the general CVD population, following standard guidelines, while choosing available treatment options known to be associated with low rates of bleeding complications. Treatments advocated for patient with haemophilia include antiplatelet therapy (aspirin and P2Y12 inhibitors), antithrombin therapy such as heparin or bivalirudin, glycoprotein IIb/IIIa inhibitors (GPIIb/IIIa inhibitors), transradial cardiac catheterization, and use of bare metal (BMS) or drug-eluting stents (DES). Antithrombotic agents with shorter half-lives that are reversible or have an antidote offer a safer choice in this setting. In addition, optimal clotting factor replacement therapy should be tailored to the increased risk of bleeding associated with invasive procedures and antithrombotic therapies, particularly during the acute phase of ACS.
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PMID:Management of cardiovascular disease in haemophilia. 2374 27


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