Home About us Contact
|
Home About us Contact | ||
|
|
||
Coagulation Factors (coagulation + factor)
Terms modified by Coagulation Factors Selected AbstractsCoagulation factors, activation markers and risk of coronary heart disease: the Northwick Park Heart StudiesJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2 2008G. D. O. LOWE [source] The role of selective angiographic embolization of the musculo-skeletal system in haemophiliaHAEMOPHILIA, Issue 4 2009E. C. RODRIGUEZ-MERCHAN Summary., The incidence of haemarthrosis as a result of a spontaneous periarticular aneurysm in haemophilia is very low. In these circumstances, angiographic embolization might be considered as a promising therapeutic and coagulation factor saving option in joint bleeds not responding to replacement of coagulation factor to normal levels. Moreover, embolization should be considered as a possible treatment for postoperative pseudoaneurysms complicating total knee arthroplasty in haemophilia. However, the pathological process of aneurysmal bleeding and clotting factor replacement is entirely different. While embolization is the treatment of choice for some periarticular complications that may occur, it is by no means a panacea for all resistant periarticular bleeds in haemophilia or for postoperative bleeding which usually settles with clotting factor replacement. Another use of arterial embolization is for the treatment of haemophilic tumours of the pelvis, because they can act as a focus for infection and cause cutaneous fistulas. When they present perforations and infections of endogenous origin, their course is usually fatal. Suitable treatment has been investigated on numerous occasions, most of the literature agreeing that the only curative treatment is surgical resection. However, surgical resection after performing arterial embolization to reduce the vascularization of the pseudotumour is a good alternative, thereby reducing the size of the pseudotumour and the risk of bleeding complications during surgery. It is important to bear in mind that despite its efficacy, arterial embolization is an invasive procedure with a reported rate of complications up to 25% (16% minor, 7% serious, 2% death). [source] Familial multiple coagulation factor deficiencies , chance associations and distinct clinical disordersHAEMOPHILIA, Issue 1 2009P. J. ROBSON Summary., The familial multiple coagulation factor deficiencies (FMCFDs) are a group of rare haemostatic disorders of genetic origin in which there is reduced plasma activity of more than one coagulation factor. FMCFDs may arise from co-incidental inheritance of separate coagulation factor deficiencies or from a single genetic or cytogenetic defect. All the FMCFDs present significant challenges in diagnosis and management yet there is little systematic evidence with which to guide clinical practice. This review summarizes the historical literature that describes the FMCFDs and introduces a refined classification of these disorders. The clinical and laboratory characteristics of the most common FMCFDs are considered in detail. [source] Successful angiographic embolization of recurrent elbow and knee joint bleeds in seven patients with severe haemophiliaHAEMOPHILIA, Issue 1 2009R. KLAMROTH Summary., In haemophilic joints with high-grade arthropathy, bleeds occur that do not respond to replacement therapy of the deficient coagulation factor. The reason may be pathologically reactive angiogenesis in chronic synovitis. Seven patients with severe haemophilia A or haemophilia B experienced recurrent massive bleeds of one elbow joint or knee joint in the absence of trauma. After initial application of factor VIII or IX (fVIII/fIX; 50 IU kg,1 bodyweight), there was only slow and never complete relief of symptoms. Despite intensive secondary prophylaxis maintaining the plasma level of factor concentrate at minimum 50%, new massive bleeds at the same location occurred. Vascular bleeding was suspected. Angiography of the arteries was performed via the femoral artery. Vessels identified as potential bleeding sources were embolized with embolization fluid (ONYX) in eight joints (six elbow and two knee joints). Under low-dose prophylactic treatment (15 IU fVIII or fIX per kg bodyweight for three times per week), no recurrent severe bleed unresponsive to coagulation factor replacement occurred after a mean observation time of 16 months after embolization. The consumption of factor concentrate decreased to one-third of the amount consumed before embolization. In conclusion, angiographic embolization with a non-adhesive liquid embolic agent might be considered as a promising therapeutic and coagulation factor saving option in joint bleeds not responding to replacement of coagulation factor to normal levels. [source] Pharmacokinetics of factors IX, recombinant human activated factor VII and factor XIIIHAEMOPHILIA, Issue 2006M.-C. POON Summary., There is now a volume of literature on the pharmacokinetics (PK) of coagulation factor concentrates, although the majority is on factor VIII (FVIII) and factor IX (FIX). PK of FIX and FVIII are different with FIX having a larger volume of distribution (Vdss), higher elimination clearance (CL), longer mean resident time (MRT) and longer terminal half-life (T1/2,,). Factor IX in vivo recovery (IVR) is also much shorter possibly due to reversible binding of FIX to the endothelium and possibly to platelets. There is considerable FIX PK variability between products (particularly between plasma-derived FIX and recombinant FIX), and between individuals. Important inter-individual factors leading to PK variability include age and body weight because plasma volume as a fraction of body weight decreases with increasing weight and hence age. Thus, IVR increases with body weight and hence age and is consequently lower in children than in adults. Absolute Vdss and CL increase linearly with body weight and age in children and adolescents, becoming stable in adults with more stable weight. Inter-individual variability also likely applies to other clotting factors, particularly to recombinant activated FVII (rFVIIa) but likely also to the less well studied factor XIII (FXIII). The former is known to have an extremely short T1/2,,, large Vdss, high CL, short MRT, whereas the latter has an extremely long T1/2,,, large Vdss, short CL and long MRT. Both are discussed in this article. Understanding of PK of specific clotting factors in individual patients is important in order to make decisions regarding appropriate dosage and dosage intervals to treat patients, and to allow by means of computer modelling the determination of dosage to achieve target trough level at various dosing intervals for patients undergoing prophylaxis. [source] Acquired haemophilia: management of bleeds and immune therapy to eradicate autoantibodiesHAEMOPHILIA, Issue 5 2005P. A. Holme Summary., Acquired haemophilia is a rare, but often severe bleeding disorder caused by autoantibodies against a coagulation factor, usually factor VIII (FVIII). Between 1997 and 2004 we observed 14 patients (mean age of 78 years) with acquired haemophilia. The aim of the present study was to investigate the effect of activated prothrombin complex concentrate (aPCC) for bleeds and the response to corticosteroids and cyclophosphamide to eradicate the offending autoantibodies. The most common clinical presentations were severe profuse bruising (12) and haematuria (5). Ten patients were classified as idiopathic. At the time of diagnosis all patients had a very low FVIII level, and one patient also showed factor IX < 1%. High levels of antibodies to FVIII varying from 10 to 1340 Bethesda units (BU) and prolonged activated partial thromboplastin time were disclosed in all patients. Eight severe bleeds were treated with aPCC (FEIBA®) at a dosage of 70 IU kg,1 every 8 h until haemostasis. Ten patients received corticosteroids and cyclophosphamide as immunomodulatory therapy. Effective haemostasis was achieved in all bleeds after aPCC. Ten of 11 patients responded either completely or partially to the immunomodulatory regime within 6 months. Five patients achieved complete response (CR) whereas partial responses were seen in five patients. The anti-CD20 monoclonal antibody rituximab was given to two patients in conventional doses and a CR was seen in one patient. aPCC is effective in treating acute bleeds in patients with acquired haemophilia with high inhibitor levels. The combination of oral corticosteroids and cyclophosphamide seems to be effective to eradicate the inhibitor. [source] Pulmonary embolism in a patient with severe congenital deficiency for factor V during treatment with fresh frozen plasmaHAEMOPHILIA, Issue 3 2005A. García-Noblejas Summary., Thrombosis is a rare complication in patients with congenital clotting factor deficiencies. In most cases, it is related to inherited procoagulant factors, use of central venous catheters or administration of coagulation factor concentrates. There are only a few case reports about thrombotic events during treatment with fresh frozen plasma (FFP). We report the case of a patient with homozygous inherited factor V deficiency, who developed a pulmonary embolism at a time of treatment with methylene blue treated FFP (MBFFP). The patient had only two other factors predisposing to thrombosis and both were acquired: obesity and bed rest. He started anticoagulant treatment with low molecular weight heparin (LMWH) while the deficient factors were replaced with MBFFP. After 8 days of treatment the patient developed a severe respiratory insufficiency. Pulmonary haemorrhage was considered among the differential diagnosis and LMWH was stopped. An inferior vena cava filter was placed without any further thrombotic complications. To our knowledge, there are no reports about patients with clotting factor deficiencies who developed a thrombotic event during treatment with MBFFP. [source] A 6-year follow-up of dosing, coagulation factor levels and bleedings in relation to joint status in the prophylactic treatment of haemophiliaHAEMOPHILIA, Issue 6 2004J. Ahnström Summary., The primary aim of this study was to investigate the possible relationship between coagulation factor level and bleeding frequency during prophylactic treatment of haemophilia after stratification of the patients according to joint scores. The secondary aim was to obtain a systematic overview of the doses of coagulation factors prescribed for prophylaxis at the Malmö haemophilia treatment centre during a 6-year period. A retrospective survey of medical records for the years 1997,2002 and pharmacokinetic study results from the 1990s was complemented by collection of blood samples for coagulation factor assay when needed. Information on the dosing and plasma levels of factor VIII or factor IX, joint scores and incidence of bleedings (joint bleeds and ,other bleeds') was compiled. The patients were stratified by age (0,6, 7,12, 13,18, 19,36 and >36 years) and joint score (0, 1,6 and >6). Individual pharmacokinetic parameters of plasma coagulation factor activities (FVIII:C and FIX:C) were estimated. Trough levels during the treatment were calculated, as well as the number of hours per week of treatment during which plasma FVIII:C/FIX:C fell below a 1, 2 or 3% target level. Fifty-one patients with haemophilia A (two moderate, 49 severe) and 13 with haemophilia B (all severe) were included, yielding data for 364 patient-years of treatment. There was a wide range of dosing schedules, the most common ones being three times a week or every other day for FVIII and twice a week or every third day for FIX. The overall relationship between FVIII:C/FIX:C levels and incidence of joint bleeding was very weak, even after stratification of the patients according to joint score. There was no relationship between coagulation factor level and incidence of other bleeds. In this cohort of patients on high-dose prophylactic treatment, dosing was based more on clinical outcome in terms of bleeding frequency than on the aim to maintain a 1% target level of FVIII:C/FIX:C. Some patients did not bleed in spite of a trough level of <1% and others did in spite of trough levels >3%. The practical implication of our findings is that dosing in prophylactic treatment of haemophilia should be individualized. Thus, proposed standard regimens should be implemented only after careful clinical consideration, with a high readiness for re-assessment and individual dose tailoring. [source] Nanofiltration of plasma-derived biopharmaceutical productsHAEMOPHILIA, Issue 1 2003T. Burnouf Summary. This review presents the current status on the use and benefits of viral removal filtration systems , known as nanofiltration , in the manufacture of plasma-derived coagulation factor concentrates and other biopharmaceutical products from human blood origin. Nanofiltration of plasma products has been implemented at a production scale in the early 1990s to improve margin of viral safety, as a complement to the viral reduction treatments, such as solvent,detergent and heat treatments, already applied for the inactivation of human immunodeficiency virus, hepatitis B and hepatitis C virus. The main reason for the introduction of nanofiltration was the need to improve product safety against non-enveloped viruses and to provide a possible safeguard against new infectious agents potentially entering the human plasma pool. Nanofiltration has gained quick acceptance as it is a relatively simple manufacturing step that consists in filtering protein solution through membranes of a very small pore size (typically 15,40 nm) under conditions that retain viruses by a mechanism largely based on size exclusion. Recent large-scale experience throughout the world has now established that nanofiltration is a robust and reliable viral reduction technique that can be applied to essentially all plasma products. Many of the licensed plasma products are currently nanofiltered. The technology has major advantages as it is flexible and it may combine efficient and largely predictable removal of more than 4 to 6 logs of a wide range of viruses, with an absence of denaturing effect on plasma proteins. Compared with other viral reduction means, nanofiltration may be the only method to date permitting efficient removal of enveloped and non-enveloped viruses under conditions where 90,95% of protein activity is recovered. New data indicate that nanofiltration may also remove prions, opening new perspectives in the development and interest of this technique. Nanofiltration is increasingly becoming a routine step in the manufacture of biopharmaceutical products. [source] Orthopaedic surgery in severe bleeding disorders: a low-volume, high-cost procedureHAEMOPHILIA, Issue 6 2002V. Mishra Summary. As more and more nations are scrutinizing their health care costs, attention has been focused on high-cost low-density disease. Assessment of actual total cost of care for haemophilia and its positive outcome becomes essential to justify support for these patients. In this study, we assessed hospital cost and diagnosis-related group (DRG) reimbursement for patients undergoing elective orthopaedic surgical procedures from May 1999 to December 1999. Hospital cost was assessed by a prospective microcost-analysis method. To identify real hospital costs, we performed registration of preoperative phase, operative phase and 1-year follow-up costs. Hospital cost included personnel costs and costs for clinical and laboratory procedures, blood products, prosthetic implants, coagulation factor concentrates and drugs. These data were compared with hospital DRG reimbursement. We included nine consecutive patients, with a mean age 38 years (19,54 years) who had had 10 major orthopaedic surgical procedures performed during the study period. Six patients had haemophilia A, two had haemophilia B and one had factor VII deficiency. Data analysis showed a mean cost of US$ 54 201 (range US$ 25 795,105 479; 1US$ = 8.5 NOK). The average actual hospital revenue (50% DRG reimbursement + income related to length of stay) was $4730 (range $ 1 308,13 601). Our study confirms that orthopaedic surgery in patients with severe bleeding disorders puts the hospital to a considerable expense. Activity-based financing, as used in Norway, does not provide a proper reimbursement for this part of the haemophilia care. [source] Thrombin generation in acute coronary syndrome and stable coronary artery disease: dependence on plasma factor compositionJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 1 2008K. BRUMMEL-ZIEDINS Summary.,Background:,Acute coronary syndrome (ACS) is associated with thrombin formation, triggered by ruptured or eroded coronary atheroma. We investigated whether thrombin generation based on circulating coagulation protein levels, could distinguish between acute and stable coronary artery disease (CAD). Methods and results:,Plasma coagulation factor (F) compositions from 28 patients with ACS were obtained after onset of chest pain. Similar data were obtained from 25 age- and sex-matched patients with stable CAD. All individuals took aspirin. Patients on anticoagulant therapy were excluded. The groups were similar in demographic characteristics, comorbidities and concomitant treatment. Using each individual's coagulation protein composition, tissue factor (TF) initiated thrombin generation was assessed both computationally and empirically. TF pathway inhibitor (TFPI), antithrombin (AT), factor II (FII) and FVIII differed significantly (P < 0.01) between the groups, with levels of FII, FVIII and TFPI higher and AT lower in ACS patients. When thrombin generation profiles from individuals in each group were compared, simulated maximum thrombin levels (P < 0.01) and rates (P < 0.01) were 50% higher with ACS while the initiation phases of thrombin generation were shorter. Empirical reconstructions of the populations reproduced the thrombin generation profiles generated by the computational model. The differences between the thrombin generation profiles for each population were primarily dependent upon the collective contribution of AT, FII and FVIII. Conclusion:,Simulations of thrombin formation based on plasma composition can discriminate between acute and stable CAD. [source] Effects of factor XI deficiency on ferric chloride-induced vena cava thrombosis in miceJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 9 2006X. WANG Summary.,Background:,Increased plasma levels of coagulation factor (F) XI are a risk factor for venous thrombosis. Objective:,To further explore the relationship between FXI and venous thrombosis, we evaluated FXI-deficient and wild-type mice in a ferric chloride (FeCl3)-induced vena cava thrombosis model. Methods and Results:,Thrombosis was induced by 3-min topical application of filter papers containing increasing concentrations of FeCl3 and the thrombus was measured at 30 min. In contrast to wild-type mice, FXI-deficient mice failed to form a thrombus with 5% FeCl3, and were partially protected against 7.5% and 10% FeCl3, respectively. The protective effect was substantially stronger than a high dose of heparin (1000 units kg,1, i.v.), clopidogrel (30 mg kg,1, p.o.) or argatroban (30 mg kg,1, i.p.). These antithrombotic agents resulted in off-scale bleeding in a tail bleeding time assay, whereas the bleeding time of FXI-deficient mice was unchanged compared to wild-type mice. In addition to its known effect on the coagulation cascade, enhanced clot lysis was demonstrated in FXI-deficient mouse and human plasma compared to those supplemented with FXIa. Conclusion:,Given the strong antithrombotic efficacy (possibly contributed by strong anticoagulant activity associated with increased fibrinolytic activity) and mild bleeding diathesis associated with FXI deficiency, therapeutic inhibition of FXI may be a reasonable therapeutic strategy to treat or prevent venous thrombosis. [source] Intracellular readthrough of nonsense mutations by aminoglycosides in coagulation factor VIIJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 6 2006M. PINOTTI Summary.,Background: Nonsense mutations in coagulation factor (F) VII potentially cause a lethal hemorrhagic diathesis. Readthrough of nonsense mutations by aminoglycosides has been studied in a few human disease models with variable results. Objectives: We investigated the K316X and W364X FVII mutations, associated with intracranial hemorrhage, and their correction by aminoglycosides. The rare nonsense mutations in FVII represent favorite models to test this strategy, because even tiny increases in the amount of functional full-length protein in patients could ameliorate hemorrhagic phenotypes. Results: A FVII,green fluorescent protein (GFP) chimaera provided us with a fluorescent model of FVII expression in living cells. Appreciable fluorescence in cells transfected with nonsense FVII,GFP mutants was detected upon geneticin treatment, thus demonstrating suppression of premature translation termination. To investigate the rescue of FVII function, nonsense variants of the native FVII without GFP (p316X,FVII and p364X,FVII) were transfected and found to secrete low amounts of FVII (,1% of Wt,FVII activity), thus suggesting a spontaneous stop codon readthrough. Geneticin treatment of cells resulted in a significant and dose-dependent increase of secreted FVII molecules (p316X,FVII, 24 ± 12 ng mL,1, 3.6 ± 0.8% of Wt,FVII activity; p364X,FVII, 26 ± 10 ng mL,1, 3.7±0.6%) characterized by reduced specific activity, thus indicating the synthesis of dysfunctional proteins. Similar results were observed with gentamicin, a commonly used aminoglycoside of potential interest for patient treatment. Conclusions: Our approach, extendable to other coagulation factors, represents an effective tool for a systematic study of the effects of aminoglycosides and neighboring sequences on nonsense codon readthrough. These results provide the rationale for a mutation-specific therapeutic approach in FVII deficiency. [source] Intrinsic stability and functional properties of disulfide bond-stabilized coagulation factor VIIIa variantsJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 6 2006A. J. GALE Summary.,Background:,The utility of purified coagulation factor (F)VIII for treatment of hemophilia A is limited in part by its instability following activation by thrombin, which is caused by spontaneous dissociation of the A2 domain from the activated FVIII (FVIIIa) heterotrimer. To prevent this A2 domain dissociation in FVIIIa, we previously engineered a cysteine pair (C664,C1826) in recombinant FVIII that formed a disulfide bond cross-linking the A2 domain in the heavy chain to the A3 domain in the light chain. This engineered disulfide bond resulted in a more stable FVIIIa. Aims:,Here, we characterize the functional parameters of C664,C1828 FVIII and of a new disulfide bond-stabilized FVIII (C662,C1828 FVIII). Methods:,In order to assess whether these FVIII variants might be good candidates for a new therapeutic agent to treat hemophilia A, we investigated a variety of functional parameters that might affect the in vivo properties of the variants, including half-life of disulfide bond-stabilized FVIII and FVIIIa and the potency of these FVIIIa molecules in the FXase complex. Results:,Both disulfide bond-stabilized variants had improved affinity for von Willebrand factor (VWF). In studies of FX activation by purified FIXa and FVIIIa, C662,C1828 FVIIIa had normal activity while C664,C1826 FVIIIa had reduced activity. Both C664,C1826 FVIIIa and C662,C1828 FVIIIa were inactivated by activated protein C (APC) but the rates of inactivation were different. Conclusion:,Overall, the specific location of the disulfide bridge between the A2 and A3 domains appears to affect functional properties of FVIIIa. In summary, introduction of engineered interdomain disulfides results in FVIIIa variants that resist spontaneous loss of activity while retaining susceptibility to APC proteolytic inactivation and maintaining VWF binding. [source] Breakpoint of a balanced translocation (X:14) (q27.1;q32.3) in a girl with severe hemophilia B maps proximal to the factor IX geneJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 3 2004J. Di Paola Summary., Hemophilia B is an X-linked bleeding disorder caused by the deficiency of coagulation factor (F)IX, with an estimated prevalence of 1 in 30 000 male births. It is almost exclusively seen in males with rare exceptions. We report a girl who was diagnosed with severe (<1%) FIX deficiency at 4 months of age. Cytogenetic studies in the patient showed a balanced translocation between one of the X-chromosomes and chromosome 14, with breakpoints at bands Xq27.1 and 14q32.3. Both parents were found to have normal chromosomes. Late replication studies by incorporation of 5-bromodeoxyuridine showed non-random inactivation of the normal X-chromosome, a phenomenon frequently seen in balanced X/autosome translocations. To map the breakpoint, fluorescent in-situ hybridization was performed. A PAC DNA probe, RP6-88D7 (which contains the FIX gene) hybridized only on the normal chromosome X as well as onto the derivative 14. Using a PAC DNA probe, RP11-963P9 that is located proximal to the FIX gene, we obtained signals on the normal and derivative X and also on the derivative 14. We conclude that the breakpoint is located within the DNA sequence of this clone mapping proximal to the FIX gene. Since the FIX gene seems to be intact in the derivative 14, the breakpoint may affect an upstream regulatory sequence that subjects the gene to position effect variegation (PEV). [source] Recognition of coagulation factor VIII by CD4+ T cells of healthy humansJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2003G-L. Hu Summary., Hemophilia A patients treated with coagulation factor (F)VIII may develop an anti-FVIII immune response. Anti-FVIII antibodies may occur also in healthy subjects. To understand the extent to which an immune response to FVIII occurs in healthy subjects, we investigated the proliferative response of blood CD4+ T cells from 90 blood donors to FVIII and to pools of overlapping synthetic peptides spanning the sequences of individual FVIII domains (A1,A3, C1,C2). Most subjects responded to FVIII and several FVIII domains. Men had stronger responses to FVIII than women, and older subjects than younger subjects. The domain-induced responses were weaker than the FVIII-induced responses, yet their intensity in individual subjects correlated with that of the response to FVIII. We examined whether Th1 and/or Th2 cells responded to FVIII in 68 subjects, by determining the CD4+ T cells that secreted interferon-, (IFN-,) or interleukin (IL)-5 after stimulation with FVIII: 25 subjects had FVIII-specific IFN-,-secreting cells, and seven of them had also FVIII-specific IL-5-secreting cells. None had only IL-5-secreting cells. Thus, a CD4+ T cell response to FVIII, which first involves Th1 cells, is common among subjects with a normal procoagulant function. [source] Use of rotation thromboelastometry (ROTEM®) to achieve successful treatment of polytrauma with fibrinogen concentrate and prothrombin complex concentrateANAESTHESIA, Issue 2 2010H. Schöchl Summary Goal-directed coagulation therapy is essential in the management of trauma patients with severe bleeding. Due to the complex nature of coagulation disorders in trauma, a quick and reliable diagnostic tool is essential. We report a severely injured multiple trauma patient who received haemostatic therapy with coagulation factor concentrates, guided by rotational thromboelastometry (ROTEM®). Initial therapy consisted of fibrinogen concentrate (Haemocomplettan® P), as maximum clot firmness in the ROTEM analyses was low, whereas clotting time was normal. Later on, prothrombin complex concentrate was given to optimise thrombin generation. This approach enabled extended emergency hemihepatectomy to be performed without using fresh frozen plasma. As the EXTEM maximum clot firmness showed good clot quality, no platelets were transfused despite low platelet counts. This case shows the potential success of treatment using both fibrinogen concentrate and prothrombin complex concentrate, not only in restoring haemostasis but also in minimising requirement for transfusion of allogeneic blood products. [source] Precise mapping of breakpoints in conserved synteny between human chromosome 1 and pig chromosomes 4, 6 and 9ANIMAL GENETICS, Issue 2 2002H. S. Sun Previous comparative mapping suggested that at least five pig chromosomes (Sscr4, 6, 9, 10 and 14) share homology with human chromosome 1 (Hsap1). A significant quantitative trait loci (QTL) for fat deposition has been identified on Sscr4 that appears to be near the junction region between Sscr4 and Sscr9 relative to Hsap1. It is of interest to define the boundaries of conserved synteny between pig chromosomes and Hsap1 to use human map information to identify putative comparative positional candidates for this QTL. Eleven genes, including Janus kinase 1 (JAK1), Prostaglandin E receptor3 (PTGER3), urate oxidase (UOX), coagulation factor 3 (F3), vascular cell adhesion molecule 1 (VCAM1), ribosomal protein L5 (RPL5), POU domain, class 2, transcription factor 1 (POU2F1), coagulation factor 5 (F5), Prostaglandin endoperoxide synthase-2 (PTGS2), myosin binding protein H (MYBPH) and Antithrombin III (SERPINC1), were selected to refine the boundaries of the blocks of conserved synteny between Hsap1 and pig chromosomes. Pig sequence tagged sites (STSs) were developed and used to physically map these 11 genes using a somatic cell hybrid panel. Eight loci have been mapped by using fluorescent in situ hybridization (FISH) to improve map resolution. Heterologous FISH was used to refine the location of VCAM1 on human chromosomes. In addition, human yeast artificial chromosomes (YACs) were mapped by heterologous FISH on pig metaphases to refine the boundaries of the regions of homology between Sscr4 and Sscr9 on Hsap1. Results from this study suggest the precise break in conserved synteny on Hsap1 corresponding to the Sscr4/6 and Sscr4/9 transitions are most likely on the Hsap1p22 and Hsap1q24,25 regions, respectively. Further, our data predict that Hsap1q21,24 is a candidate region for the backfat QTL localized to Sscr4. [source] Biosynthesis of FVIII in megakaryocytic cells: improved production and biochemical characterizationBRITISH JOURNAL OF HAEMATOLOGY, Issue 5 2004Marie-Hélène Rodriguez Summary 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. [source] Autoantibodies to coagulation factorsHAEMOPHILIA, Issue 102 2010J.-M. R. SAINT-REMY Summary., Tolerance to autoantigens such as coagulation factors is the result of censoring mechanisms occurring at the level of the thymus and bone marrow for autoreactive T and B cells, respectively. In addition, peripheral mechanisms, both intrinsic and extrinsic further control activation of autoreactive cells that have escaped central deletion. Emergence of autoimmunity can occur from disturbances of these control mechanisms by a number of events, many of which are incompletely understood. Insight into this clinically important field is expected from exploitation of recent animal models. [source] Haemophilia care then, now and in the futureHAEMOPHILIA, Issue 2009J. OLDENBURG Summary., Epidemiological data show the benefits of dramatically improved haemophilia care in all life-stages. There are improved administration techniques and dosing regimens, a shift from on-demand treatment to prophylaxis, successful treatment protocols for immune tolerance induction in patients with inhibitors and enhanced approaches to overall patient management. Improvements also include the introduction of virus inactivation methods for plasma derived clotting factor concentrates and the development of recombinant factor VIII therapy, which practically eliminated the risk of infectious disease transmission. Recombinant factor concentrates are recommended as treatment of choice by several guidelines today. All these developments have resulted in increased health-related quality of life and life expectancy in haemophilia patients, who are transitioning from childhood to adulthood with healthy joints and an overall healthy status today. Because of increased life expectancy, these patients are expected to experience age-related clinical problems that were not previously observed in this population. With respect to this, the spectrum of haemophilia care will be extended to diseases of older ages with the need of including further disciplines in comprehensive haemophilia care programmes. Despite these advances, the short half-life of factor VIII, requiring re-administration every 2 or 3 days and the development of inhibitors remains a challenge. Bayer's research and development currently focuses on the optimization of recombinant coagulation factors to address these challenges. Haemophilia care has experienced significant improvements within the past decades. Novel technologies and continued clinical research have facilitated the development of treatment regimen that resulted in dramatic increases in the life expectancy and quality of life of haemophilia patients. To set the scene for the following papers dealing with haemophilia care from paediatrics to geriatrics, developments behind these improvements and some aspects of future research will be presented in this paper. [source] In vivo recovery of factor VIII and factor IX: intra- and interindividual variance in a clinical settingHAEMOPHILIA, Issue 1 2007S. BJÖRKMAN Summary., In vivo recovery (IVR) is traditionally used as a parameter to characterize the pharmacokinetic properties of coagulation factors. It has also been suggested that dosing of factor VIII (FVIII) and factor IX (FIX) can be adjusted according to the need of the individual patient, based on an individually determined IVR value. This approach, however, requires that the individual IVR value is more reliably representative for the patient than the mean value in the population, i.e. that there is less variance within than between the individuals. The aim of this investigation was to compare intra- and interindividual variance in IVR (as U dL,1 per U kg,1) for FVIII and plasma-derived FIX in a cohort of non-bleeding patients with haemophilia. The data were collected retrospectively from six clinical studies, yielding 297 IVR determinations in 50 patients with haemophilia A and 93 determinations in 13 patients with haemophilia B. For FVIII, the mean variance within patients exceeded the between-patient variance. Thus, an individually determined IVR value is apparently no more informative than an average, or population, value for the dosing of FVIII. There was no apparent relationship between IVR and age of the patient (1.5,67 years). For FIX, the mean variance within patients was lower than the between-patient variance, and there was a significant positive relationship between IVR and age (13,69 years). From these data, it seems probable that using an individual IVR confers little advantage in comparison to using an age-specific population mean value. Dose tailoring of coagulation factor treatment has been applied successfully after determination of the entire single-dose curve of FVIII:C or FIX:C in the patient and calculation of the relevant pharmacokinetic parameters. However, the findings presented here do not support the assumption that dosing of FVIII or FIX can be individualized on the basis of a clinically determined IVR value. [source] Use of pharmacokinetics in the coagulation factor treatment of patients with haemophiliaHAEMOPHILIA, Issue 6 2005A. D. Shapiro Summary., Dosing decisions for replacement coagulation factors in patients with haemophilia should be made on an individual patient basis, with the required dose dependent on factors including the clinical situation, the severity of the factor deficiency, and the location and extent of bleeding. Moreover, there is considerable variability in the pharmacokinetics of coagulation products that needs to be considered; in particular, with both factor (F) IX and FVIII products, there is considerable inter-patient variability in in vivo recovery and terminal half-life values. In the present report, we provide a practical guide to calculating and applying pharmacokinetic parameters relevant to the optimal dosing of coagulation products. We discuss the conduct of a pharmacokinetic study in an individual patient, how to calculate pharmacokinetic values from raw data and clinical situations where an individual pharmacokinetic study is helpful. We highlight the importance of considering an individual pharmacokinetic study in all patients starting a new coagulation product. [source] A 6-year follow-up of dosing, coagulation factor levels and bleedings in relation to joint status in the prophylactic treatment of haemophiliaHAEMOPHILIA, Issue 6 2004J. Ahnström Summary., The primary aim of this study was to investigate the possible relationship between coagulation factor level and bleeding frequency during prophylactic treatment of haemophilia after stratification of the patients according to joint scores. The secondary aim was to obtain a systematic overview of the doses of coagulation factors prescribed for prophylaxis at the Malmö haemophilia treatment centre during a 6-year period. A retrospective survey of medical records for the years 1997,2002 and pharmacokinetic study results from the 1990s was complemented by collection of blood samples for coagulation factor assay when needed. Information on the dosing and plasma levels of factor VIII or factor IX, joint scores and incidence of bleedings (joint bleeds and ,other bleeds') was compiled. The patients were stratified by age (0,6, 7,12, 13,18, 19,36 and >36 years) and joint score (0, 1,6 and >6). Individual pharmacokinetic parameters of plasma coagulation factor activities (FVIII:C and FIX:C) were estimated. Trough levels during the treatment were calculated, as well as the number of hours per week of treatment during which plasma FVIII:C/FIX:C fell below a 1, 2 or 3% target level. Fifty-one patients with haemophilia A (two moderate, 49 severe) and 13 with haemophilia B (all severe) were included, yielding data for 364 patient-years of treatment. There was a wide range of dosing schedules, the most common ones being three times a week or every other day for FVIII and twice a week or every third day for FIX. The overall relationship between FVIII:C/FIX:C levels and incidence of joint bleeding was very weak, even after stratification of the patients according to joint score. There was no relationship between coagulation factor level and incidence of other bleeds. In this cohort of patients on high-dose prophylactic treatment, dosing was based more on clinical outcome in terms of bleeding frequency than on the aim to maintain a 1% target level of FVIII:C/FIX:C. Some patients did not bleed in spite of a trough level of <1% and others did in spite of trough levels >3%. The practical implication of our findings is that dosing in prophylactic treatment of haemophilia should be individualized. Thus, proposed standard regimens should be implemented only after careful clinical consideration, with a high readiness for re-assessment and individual dose tailoring. [source] Role of fibrinogen-, factor VIII- and XIII-mediated clot propagation in gelatin haemodilutionACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2009A. A. SCHRAMKO Background: Gelatin solution impairs coagulation. The mechanism of coagulopathy is incompletely defined. The purpose of this study was to evaluate the capacity of single coagulation factors to reverse gelatin-promoted whole-blood coagulation disorders in vitro. Methods: Venous blood was withdrawn from 12 volunteers in a crossover study. Four percent succinylated gelatin was added to citrated whole-blood samples to make a 40 vol% end-concentration of gelatin. The baseline and 40 vol% samples, and samples with addition of fresh-frozen plasma (FFP), fibrinogen, coagulation factors XIII (FXIII) or VIII, together with the von Willebrand factor (FVIII+vWF), were analysed by thromboelastometry (ROTEM®). Coagulation was initiated by tissue thromboplastin (ExTEM®) with and without cytochalasin to determine the functional component of fibrinogen (FibTEM®). Results: Initiation of coagulation and fibrin formation were delayed at 40 vol% gelatin dilution. At this stage, the median (25th,75th percentiles) maximum clot firmness (MCF) was 76.3 (65.9,80.0) and 32.5 (27.4,45.0)% of the pre-dilution value in ExTEM® and FibTEM® thromboelastometry, respectively. Coagulation time was corrected by addition of fibrinogen and FFP in ExTEM® and FibTEM® analysis, whereas FVIII or FXIII had minimal effects. MCF was partly restored only by FFP in ExTEM®. In FibTEM® analysis, MCF improved more by fibrinogen than by FVIII+VWF, FXIII or FFP. Conclusions: Gelatin-induced whole-blood coagulation disorder in vitro is mainly dependent on the initial fibrinogen,fibrin interaction. The proposed mechanism might suggest not to reverse gelatin coagulopathy solely by fibrinogen administration. The administration of FFP, a mixture of different coagulation factors, reversed the gelatin-induced in vitro coagulopathy the best. [source] REVIEW ARTICLE: Hyperglycemia: a prothrombotic factor?JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2010B. A. LEMKES Summary., Diabetes mellitus is characterized by a high risk of atherothrombotic events. What is more, venous thrombosis has also been found to occur more frequently in this patient group. This prothrombotic condition in diabetes is underpinned by laboratory findings of elevated coagulation factors and impaired fibrinolysis. Hyperglycemia plays an important role in the development of these hemostatic abnormalities, as is illustrated by the association with glycemic control and the improvement upon treatment of hyperglycemia. Interestingly, stress induced hyperglycemia, which is often transient, has also been associated with poor outcome in thrombotic disease. Similar laboratory findings suggest a common effect of acute vs. chronic hyperglycemia on the coagulation system. Many mechanisms have been proposed to explain this prothrombotic shift in hyperglycemia, such as a direct effect on gene transcription of coagulation factors caused by hyperglycemia-induced oxidative stress, loss of the endothelial glycocalyx layer, which harbours coagulation factors, and direct glycation of coagulation factors, altering their activity. In addition, both chronic and acute hyperglycemia are often accompanied by hyperinsulinemia, which has been shown to have prothrombotic effects as well. In conclusion, the laboratory evidence of the effects of both chronic and acute hyperglycemia suggests a prothrombotic shift. Additionally, hyperglycemia is associated with poor clinical outcome of thrombotic events. Whether intensive treatment of hyperglycemia can prevent hypercoagulability and improve clinical outcome remains to be investigated. [source] Factor Xa or thrombin: is factor Xa a better target?JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2007J. ANSELL Summary., Existing vitamin K antagonists (VKAs) have drawbacks that limit their effectiveness, safety, and overall frequency of use. Oral anticoagulants in development with targeted action against individual coagulation factors, specifically direct factor (F) Xa and IIa inhibitors, appear to have pharmacokinetic and pharmacodynamic properties that overcome the limitations of the VKAs. Based on the theory of how coagulation factors interact, on the results of in vitro studies, and on clinical outcomes, there is accumulating evidence that FXa may represent a better target for inhibition than FIIa. This is based on an understanding of the amplified nature of coagulation factor interactions and fibrin formation, the need for smaller doses of an anticoagulant to block coagulation progression earlier in the sequence of reactions, the evidence for incomplete suppression of thrombin generation with direct thrombin inhibitors, evidence for rebound hypercoagulability with thrombin inhibitors, and clinical results with the indirect, parenteral, FXa inhibitor (fondaparinux), as well as early phase II results of new oral Xa and IIa inhibitors compared with enoxaparin. The latter studies, although not comparative, provide some evidence for the effectiveness and safety of Xa inhibitors at a range of doses not seen with the direct IIa inhibitors. [source] More on: pathogenic antibodies to coagulation factors.JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 1 2006Part II: fibrinogen, factor V, factor XI, factor XII, factor XIII, protein C, prothrombin, thrombin, von Willebrand factor No abstract is available for this article. [source] Two subpopulations of thrombin-activated platelets differ in their binding of the components of the intrinsic factor X-activating complexJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 11 2005M. A. PANTELEEV Summary., Binding of fluorescein-labeled coagulation factors IXa, VIII, X, and allophycocyanin-labeled annexin V to thrombin-activated platelets was studied using flow cytometry. Upon activation, two platelet subpopulations were detected, which differed by 1,2 orders of magnitude in the binding of the coagulation factors and by 2,3 orders of magnitude in the binding of annexin V. The percentage of the high-binding platelets increased dose dependently of thrombin concentration. At 100 nm of thrombin, platelets with elevated binding capability constituted ,4% of total platelets and were responsible for the binding of ,50% of the total bound factor. Binding of factors to the high-binding subpopulation was calcium-dependent and specific as evidenced by experiments in the presence of excess unlabeled factor. The percentage of the high-binding platelets was not affected by echistatin, a potent aggregation inhibitor, confirming that the high-binding platelets were not platelet aggregates. Despite the difference in the coagulation factors binding, the subpopulations were indistinguishable by the expression of general platelet marker CD42b and activation markers PAC1 (an epitope of glycoprotein IIb/IIIa) and CD62P (P-selectin). Dual-labeling binding studies involving coagulation factors (IXa, VIII, or X) and annexin V demonstrated that the high-binding platelet subpopulation was identical for all coagulation factors and for annexin V. The high-binding subpopulation had lower mean forward and side scatters compared with the low-binding subpopulation (,80% and ,60%, respectively). In its turn, the high-binding subpopulation was not homogeneous and included two subpopulations with different scatter values. We conclude that activation by thrombin induces the formation of two distinct subpopulations of platelets different in their binding of the components of the intrinsic fX-activating complex, which may have certain physiological or pathological significance. [source] Synthetic selective inhibitors of coagulation factor Xa strongly inhibit thrombin generation without affecting initial thrombin forming time necessary for platelet activation in hemostasisJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 4 2004M. Ieko Summary., DX-9065a and JTV-803, synthetic selective inhibitors of activated factor X (FXa), have recently been demonstrated as strongly effective antithrombotic agents in animal thrombosis models, yet with a low risk of bleeding. The aim of the present study was to elucidate these characteristics. Using a chromogenic assay with purified coagulation factors, 73.9% of thrombin generation was suppressed by the addition of DX-9065a (0.20 µm) and 75.7% by JTV-803 (0.18 µm). Inhibition by argatroban (0.19 µm) was less (36.0%) and initial thrombin forming time (T50), the time required to generate 50% thrombin activity in vitro, which is considered important for platelet aggregation in hemostasis, was significantly prolonged by argatroban. In contrast, DX-9065a and JTV-803 had no apparent influence on T50, suggesting that initial thrombin was formed immediately, as in the control. We also investigated platelet aggregation in defibrinated plasma induced by tissue factor, to clarify whether initial thrombin contributes to hemostasis. Aggregation was not affected by the addition of either FXa inhibitor, whereas it was significantly reduced by argatroban. Our results suggest that initial thrombin, which is formed despite the presence of a FXa inhibitor, can activate platelets. We concluded that DX-9065a and JTV-803 are able to inhibit thrombin generation significantly without affecting the formation of initial thrombin for platelet activation, which may contribute to hemostasis through the preservation of normal bleeding time. [source] | |||||||||||||||||||||||||