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ABSTRACT: Microparticles (MP) are sub-micron sized vesicles released by activated or apoptotic cells. They are generally defined as 0.1 to 1 μm membrane particles that expose the anionic phospholipid phosphatidylserine (PS) and membrane antigens representative of their cellular origin [1]. It is now well recognized that MP behave as vectors of bioactive molecules, playing a role in blood coagulation, inflammation, cell activation and cancer metastasis. In clinical practice, circulating MP originating from blood and vascular cells are elevated in a variety of prothrombotic and inflammatory disorders, cardiovascular diseases, autoimmune conditions, infectious diseases and cancer [1-3]. © 2013 International Society on Thrombosis and Haemostasis.
Journal of Thrombosis and Haemostasis 04/2013; · 5.73 Impact Factor
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ABSTRACT: Elevated levels of tissue factor positive (TF(+)) microparticles (MPs) are observed in plasma from a variety of patients with an increased risk of thrombosis. We and others have described the measurement of TF activity in MPs isolated from plasma. The aim of this study was to investigate the effects of pre-analytical and analytical variables on TF activity of MPs isolated from blood of healthy volunteers either untreated or treated ex vivo with bacterial lipopolysaccharide.
We evaluated the following parameters: use of different centrifugation speeds to isolate the MPs; comparison of TF activity of MPs isolated from platelet poor plasma versus platelet free plasma; effect of freeze/thaw on MP TF activity; and comparison of the MP TF activity assay with the measurement of TF protein by ELISA or flow cytometry.
MPs prepared from platelet poor plasma by centrifugation at 20,000×g or 100,000×g for 15 minutes had similar levels of TF activity. However, significantly less TF activity was found in MPs isolated from platelet free plasma compared with platelet poor plasma. Interestingly, freeze/thawing of the plasma showed donor to donor variation in MP TF activity, with a moderate increase in some individuals.
TF(+) MPs can be quantitatively isolated from platelet poor or platelet free plasma by centrifugation at 20,000×g for 15 minutes. Measurement of MP TF activity in plasma may be used to detect a prothrombotic state in patients with various diseases.
Thrombosis Research 07/2011; 129(1):80-5. · 2.44 Impact Factor
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Journal of Thrombosis and Haemostasis 05/2011; 9(7):1429-31. · 5.73 Impact Factor
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Journal of Thrombosis and Haemostasis 11/2010; 8(11):2571-4. · 5.73 Impact Factor
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ABSTRACT: SUMMARY: While the majority of this session will deal with selected inherited vascular abnormalities that may manifest as a haemorrhagic disorder, the initial discussion by Dr Key will focus on the interplay between the vessel wall and components of the coagulation system, with a focus on haemophilia A and B. Although it is generally accepted that physiological haemostasis is triggered by contact of blood with tissue factor (TF), there remains some controversy regarding the cellular origin of TF in vivo. In addition, the initiation and propagation of thrombin generation are highly dependent on the balance of pro- and anticoagulant functions of endothelium, a profile that varies significantly throughout the vasculature. Drs De Paepe and Malfait address heritable collagen disorders such as the Ehlers-Danlos syndromes (EDS), a heterogeneous group of diseases involving the skin, ligaments and joints, blood vessels and internal organs. Most EDS subtypes are caused by mutations in genes encoding fibrillar collagens, or in genes coding for enzymes involved in posttranslational modifications of collagens. Accurate biochemical and molecular testing is now available for most EDS subtypes and can direct genetic counselling and medical management for these disorders. Dr Shovlin reviews recent developments in hereditary haemorrhagic telengiectasia (HHT), a frequently undiagnosed disorder characterized by arteriovenous malformations in multiple organs. These abnormal blood vessels are the result of mutations in one of a number of genes whose protein products influence TGF-beta signalling in vascular endothelial cells. Several HHT management guidelines have been published and are discussed.
Haemophilia 07/2010; 16 Suppl 5:146-51. · 2.60 Impact Factor
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Journal of Thrombosis and Haemostasis - J THROMB HAEMOST. 01/2010;
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ABSTRACT: Malignant gliomas are associated with a very high risk of venous thromboembolism (VTE). While many clinical risk factors have previously been described in brain tumor patients, the risk of VTE associated with newer anti-angiogenic therapies such as bevacizumab in these patients remains unclear. When VTE occurs in this patient population, concern regarding the potential for intracranial hemorrhage complicates management decisions regarding anticoagulation, and these patients have a worse prognosis than their VTE-free counterparts. Risk stratification models identifying patients at high risk of developing VTE along with predictive plasma biomarkers may guide the selection of eligible patients for primary prevention with pharmacologic thromboprophylaxis. Recent studies exploring disordered coagulation, such as increased expression of tissue factor (TF), and tumorigenic molecular signaling may help to explain the increased risk of VTE in patients with malignant gliomas.
Journal of Thrombosis and Haemostasis 11/2009; 8(2):221-7. · 5.73 Impact Factor
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Haemophilia 09/2009; 15(6):1337-8. · 2.60 Impact Factor
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ABSTRACT: We used data collected as part of the Universal Data Collection (UDC) surveillance project in haemophilia treatment centers (HTC) to study the incidence, risk factors and impact of septic arthritis among males with haemophilia. Patients participating in UDC on two or more occasions were included. Cases were defined as patients with documented joint infection. Characteristics of the cases were compared with those of haemophilia patients without infection. Among the 8026 eligible patients with 36 015 person-years of follow-up, 30 (0.37%) had a documented joint infection (incidence rate 83 per 100 000 person-years). In a logistic regression model, only increasing age (OR = 6.1 for age > or =30), race/ethnicity other than white (OR = 3.9), presence of inhibitor (OR = 3.9), invasive procedure in the past year (OR = 2.7) and presence of one or more target joints (OR = 3.2) remained statistically significant. Central venous access devices use and hepatitis C virus and HIV infection were not associated with septic arthritis risk after adjusting for potential confounders. Study limitations include possible underestimation of septic arthritis rate in this population and its retrospective design. We conclude that septic arthritis is an uncommon complication of haemophilia occurring primarily in joints most affected by bleeding and reparative surgical interventions.
Haemophilia 06/2008; 14(3):494-503. · 2.60 Impact Factor
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ABSTRACT: Greater understanding of the cellular interactions associated with tissue factor (TF), activated factor (F) VII and TF-FVIIa complexes is likely to provide considerable clinical benefit. This article reviews current knowledge on the function and regulation of TF and its role in a range of biological processes, including hemostasis, thrombosis and inflammation.
Journal of Thrombosis and Haemostasis 07/2007; 5(6):1097-105. · 5.73 Impact Factor
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Bone Marrow Transplantation 01/2007; 38(12):825-8. · 3.75 Impact Factor
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ABSTRACT: Whether atherosclerotic disease predisposes to venous thrombosis is uncertain.
To determine whether subclinical atherosclerosis, manifested as increased carotid intima-media thickness (IMT) or presence of carotid plaque, is associated with increased incidence of venous thromboembolism (VTE).
The Atherosclerosis Risk in Communities study is a prospective cohort of adults aged 45-64 years, examined at baseline (1987-89) and followed for cardiovascular events. Bilateral carotid ultrasound for IMT measurements was done at baseline for portions of the common and internal carotid arteries, and carotid bifurcation and also to detect the presence of carotid plaque. Exclusion criteria included baseline anticoagulant use, history of coronary heart disease, stroke, or VTE, and incomplete data. First VTE during follow-up was validated using abstracted medical records.
Among 13,081 individuals followed for a mean of 12.5 years, 225 first VTE events were identified. Unadjusted hazard ratios (HR) (95% CI) of VTE across quartiles of baseline IMT were 1.0, 1.16 (0.77-1.75), 1.64 (1.12-2.40), and 1.52 (1.03-2.25). However, this association disappeared after adjustment for age, sex, and ethnicity (HRs: 1.0, 1.06, 1.40, and 1.18). Further adjustment for body mass index and diabetes weakened the relative risks even further. Presence of carotid plaque at baseline also was not associated with VTE occurrence; adjusted HR = 0.97, 95% CI = 0.72-1.29.
Increased carotid IMT or presence of carotid plaque was not associated with an increased incidence of VTE in this middle-aged cohort, suggesting subclinical atherosclerosis itself is not a VTE risk factor.
Journal of Thrombosis and Haemostasis 10/2006; 4(9):1909-13. · 5.73 Impact Factor
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ABSTRACT: We present the case of a 61-year-old man with severe haemophilia A and a high-titre factor VIII inhibitor who underwent successful orthotopic liver transplantation (OLT) for hepatocellular carcinoma. Postoperatively, a modest early anamnestic response to FVIII was followed by immunological tolerance to FVIII. This case illustrates the technical feasibility of OLT in some patients with high-titre inhibitors to FVIII, and suggests that immune tolerance may be induced by endogenously produced FVIII from the transplanted organ.
Haemophilia 12/2004; 10(6):735-7. · 2.60 Impact Factor
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W Jy,
L L Horstman,
J J Jimenez,
Y S Ahn,
E Biró,
R Nieuwland,
A Sturk,
F Dignat-George,
F Sabatier,
L Camoin-Jau,
J Sampol,
B Hugel,
F Zobairi,
J M Freyssinet,
S Nomura,
A S Shet, N S Key,
R P Hebbel
Journal of Thrombosis and Haemostasis 11/2004; 2(10):1842-51. · 5.73 Impact Factor
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Journal of Thrombosis and Haemostasis 09/2004; 2(10):1848 - 1850. · 5.73 Impact Factor
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ABSTRACT: Iliopsoas haemorrhage in patients with bleeding disorders is a potentially life-threatening condition, with significantly associated morbidity. Despite its clinical importance, little has been published on the frequency, complications or outcomes of this entity since the advent of modern therapies for haemophilia. In a retrospective review of 297 patients with bleeding disorders followed at our centre, we identified 46 episodes of iliopsoas haemorrhage in 31 patients. Patients presented primarily with thigh, hip and/or groin pain, and frequently had flexion hip contracture, femoral nerve paresthesia, and >2 g dL(-1) haemoglobin drop. The duration of symptoms prior to seeking medical attention was 3.8 +/- 4 days. Nineteen of 155 patients (12.3%) with haemophilia A had 28 episodes of iliopsoas bleed; 52.6% of these patients had severe haemophilia. Of these 19 patients with haemophilia A who had iliopsoas haemorrhage, seven (36.8%) had an inhibitor to factor VIII (FVIII), and accounted for one-half of the bleeding episodes. Nine of 66 patients (13.6%) with haemophilia B had 15 episodes of iliopsoas haemorrhage; 22.2% of these patients had severe haemophilia, including one patient with an inhibitor to FIX who had two iliopsoas bleeds. The mean duration of therapy was 18.7 +/- 11.9 days, and the duration of hospitalization was 12.3 +/- 9.1 days. The length of hospital stay was significantly longer in patients with inhibitors, when compared with patients without inhibitors (19.1 +/- 5.8 days vs. 7.6 +/- 7.8 days; P<0.0001) with higher factor consumption, although the total duration of therapy was not significantly different. Patients with inhibitors were over-represented in the cohort of haemophiliacs with iliopsoas bleed. Patients with inhibitors who had iliopsoas bleeds remained hospitalized longer, although the duration of therapy was the same as patients with no inhibitors. There was a low frequency of recurrent bleed (2.8%).
Haemophilia 11/2003; 9(6):721-6. · 2.60 Impact Factor
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ABSTRACT: Acquired factor VII (FVII) deficiency in the absence of vitamin K deficiency, oral anticoagulant therapy, synthetic liver dysfunction, or DIC is rare, with only a handful of cases thus far reported. In the period from 1990 to 1996 we identified eight patients with acquired FVII deficiency, all of whom presented with prolongation of the prothrombin time (PT) in the first 2 weeks following stem cell transplantation (SCT). The mean plasma FVII clotting activity (FVII:c) was 22% (range 8-35%) with an approximately equivalent reduction in FVII antigen (FVII:Ag) level. Mean plasma levels of fibrinogen and factors II, V, IX, and X were normal. Protein C activity was significantly depressed in only one of the three patients in whom it was measured. Several patients experienced bleeding complications, and hemorrhage directly accounted for death in two cases. Veno-occlusive disease of the liver developed in three patients. We conclude that FVII deficiency should be considered in the differential diagnosis of prolonged PT in patients who have recently undergone SCT. The mechanism of this acquired deficiency state remains to be defined.
Bone Marrow Transplantation 04/2002; 29(5):403-8. · 3.75 Impact Factor
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ABSTRACT: Porcine factor VIII (pFVIII), which is used to control bleeding in patients with congenital or acquired haemophilia who have high-titre neutralizing antibodies to human FVIII, is not known to increase the risk of arterial or venous thrombosis. We have recently encountered a patient with acquired haemophilia who developed a thrombotic left middle cerebral artery distribution stroke while being treated with pFVIII. To our knowledge, this is the first such reported thrombotic event. We speculate that platelet activation induced by pFVIII may have contributed to thrombosis and suggest that pFVIII be used with caution in elderly patients with pre-existing cardiovascular risk factors.
Haemophilia 02/2002; 8(1):56-8. · 2.60 Impact Factor
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Thrombosis and Haemostasis 04/2001; 85(3):375-6. · 5.04 Impact Factor
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ABSTRACT: The studies we reviewed here have begun to clarify the complex cellular mechanisms involved in the immune response to fVIII, and the circumstances under which fVIII inhibitors develop. Further characterization and comparison of the immune response to fVIII in both hemophilia patients and healthy subjects will help to further elucidate these mechanisms. The murine hemophilia model will hopefully provide further insights into the mechanisms of inhibitor formation, and prove to be a suitable tool for the design and testing of therapeutic strategies aimed at preventing the development of fVIII inhibitors.
Advances in experimental medicine and biology 02/2001; 489:119-34. · 1.09 Impact Factor
