Benjamin Brenner

Fondaparinux for the Treatment of Superficial-Vein Thrombosis in the Legs

BACKGROUND The efficacy and safety of anticoagulant treatment for patients with acute, symptomatic superficial-vein thrombosis in the legs, but without concomitant deep-vein thrombosis or symptomatic pulmonary embolism at presentation, have not been established. METHODS In a randomized, double-blind trial, we assigned 3002 patients to receive either fondaparinux, administered subcutaneously at a dose of 2.5 mg once daily, or placebo for 45 days. The primary efficacy outcome was a composite of death from any cause or symptomatic pulmonary embolism, symptomatic deep-vein thrombosis, or symptomatic extension to the saphenofemoral junction or symptomatic recurrence of superficial-vein thrombosis at day 47. The main safety outcome was major bleeding. The patients were followed until day 77. RESULTS The primary efficacy outcome occurred in 13 of 1502 patients (0.9%) in the fondaparinux group and 88 of 1500 patients (5.9%) in the placebo group (relative risk reduction with fondaparinux, 85%; 95% confidence interval [CI], 74 to 92; P<0.001). The incidence of each component of the primary efficacy outcome was significantly reduced in the fondaparinux group as compared with the placebo group, except for the outcome of death (0.1% in both groups). The rate of pulmonary embolism or deep-vein thrombosis was 85% lower in the fondaparinux group than in the placebo group (0.2% vs. 1.3%; 95% CI, 50 to 95; P<0.001). Similar risk reductions were observed at day 77. A total of 88 patients would need to be treated to prevent one instance of pulmonary embolism or deep-vein thrombosis. Major bleeding occurred in one patient in each group. The incidence of serious adverse events was 0.7% with fondaparinux and 1.1% with placebo. CONCLUSIONS Fondaparinux at a dose of 2.5 mg once a day for 45 days was effective in the treatment of patients with acute, symptomatic superficial-vein thrombosis of the legs and did not have serious side effects. (Funded by GlaxoSmithKline; ClinicalTrials.gov number, NCT00443053.)

Cardiac involvement in patients with primary antiphospholipid syndrome

To evaluate cardiac involvement in primary antiphospholipid syndrome, two-dimensional and Doppler echocardiographic studies were performed in 34 consecutive patients with this syndrome. All patients had an increased level of serum anticardiolipin antibodies with no evidence of malignancy or systemic lupus erythematosus. The clinical manifestations of primary antiphospholipid syndrome were arterial thrombosis in 14 patients, venous thrombosis in 6 and recurrent fetal loss in 14. Valvular lesions were observed on two-dimensional echocardiography in 11 patients (32%) (9 women and 2 men), aged 24 to 57 years (mean +/- 1 SD 36 +/- 10). Abnormal echocardiographic findings were observed in 9 (64%) of 14 patients with arterial thrombosis versus 1 (17%) of 6 patients with venous thrombosis and 1 (7%) of 14 patients with recurrent fetal loss. The most common echocardiographic abnormality was mitral leaflet thickening, found in five patients; this was associated with mitral regurgitation in three and with combined mild mitral stenosis and regurgitation in one patient. Localized subvalvular mitral thickening was observed in one patient and calcification of the anulus in another. Aortic valve thickening was observed in two patients, one of whom also had a moderate degree of aortic regurgitation. Vegetation-like lesions on the mitral or aortic valve were found in two patients. It is concluded that valvular lesions are commonly found in primary antiphospholipid syndrome, particularly when the syndrome is manifested by peripheral arterial thrombosis. The location and appearance of valvular lesions in this syndrome are heterogeneous. Most patients have no clinically significant valvular disease. Two-dimensional and Doppler echocardiographic studies are often informative in these patients.

Haematological cancers in pregnancy

Haematological cancer in pregnancy, although rare, poses a substantial risk to both mother and fetus. Hodgkins lymphoma is the most common, followed by non-Hodgkin lymphoma and acute leukaemia. Diagnosis of haematological cancers is challenged by an overlap of the disease and gestation-related symptoms and limitations of imaging studies in pregnancy. Data for safety and effectiveness of therapy are scarce and mostly retrospective. This report provides updated guidance for management, focusing on chemotherapy and biological agents. The primary goal of treatment is to preserve the mothers health; hence, pregnancy termination is often advisable at early stages, allowing delivery of adequate therapy. However, at later gestational stages treatment is often feasible. Pregnancy-related hypercoagulability, augmented by cancer, often necessitates thromboprophylaxis. The consequences and complex management of haematological cancer during pregnancy emphasise the need for collaborative research, focusing on basic mechanisms of disease and prospective epidemiological studies.

Microparticles, thrombosis and cancer

Microvesicles comprised of exosomes and microparticles are shed from both normal and malignant cells upon cell activation or apoptosis. Microvesicles promote clot formation, mediate pro-inflammatory processes, facilitate cell-to-cell interactions, transfer proteins and mRNA to cells, and induce cell signalling. Microparticles bearing tissue factor play a central role in coagulation initiation and thrombus formation. This chapter will review earlier studies which focus on the role of procoagulant microvesicles in cancer thrombogenicity, and discuss the effects of microvesicles on vascular cell dysfunction and angiogenesis. In addition, this chapter will present new findings which characterize the haemostatic balance of microparticles, and suggest a method that may potentially serve to predict a state of hypercoagulability in cancer patients. This chapter highlights the interplay between microvesicles, coagulation factors and cancer.

Acquired activated protein C resistance is common in cancer patients and is associated with venous thromboembolism

PURPOSE Cancer patients have an increased risk for venous thromboembolism. Because activated protein C resistance is a common risk factor for venous thromboembolism, we prospectively evaluated the activated protein C sensitivity ratio and factor V Leiden mutation in cancer patients with and without venous thromboembolism. SUBJECTS AND METHODS We studied 55 consecutive cancer patients with deep vein thrombosis, 58 cancer patients with no history of venous thromboembolism, 54 patients with venous thromboembolism without malignancy, and 56 healthy controls. The presence of factor V Leiden mutation was determined by polymerase chain reaction and allele specific restriction digestion. The activated protein C sensitivity ratio was expressed as the ratio of activated partial thromboplastin times measured in the presence and absence of activated protein C; a ratio <2.0 in patients who did not have factor V Leiden was considered to indicate acquired activated protein C resistance. RESULTS The prevalence of factor V Leiden mutation in cancer patients with thromboembolism (1 of 55, 2%) did not differ significantly from those in cancer patients without thromboembolism (4 of 58, 7%) or normal controls (2 of 56, 4%), but was significantly lower than that of patients with thromboembolism without cancer (18 of 54, 33%, P <0.001). The prevalence of acquired activated protein C resistance was significantly greater in cancer patients with thromboembolism (29 of 54, 54%, P = 0.001) compared with the other groups: 9 of 54 (17%) in cancer patients without thromboembolism, 7 of 36 (19%) in patients with thromboembolism without cancer, and none of the normal controls. CONCLUSION Although factor V Leiden is not a major risk factor for thrombosis in cancer patients, acquired activated protein C resistance is common and may contribute to the thrombotic tendency in these patients.

Nitric oxide: a key factor behind the dysfunctionality of endothelial progenitor cells in diabetes mellitus type-2

Diabetes mellitus type-2 (DM-2) contributes to atherogenesis by inducing endothelial cell injury and dysfunction. Endothelial progenitor cells (EPCs) are essential to blood vessel formation, can differentiate into mature endothelial cells, and promote the repair of damaged endothelium. In DM-2, the circulating EPC count is low and their functionality is impaired. The mechanisms that underlie this reduced count and impaired functionality are poorly understood. Nitric oxide (NO) is a short-lived signalling molecule that is produced by vascular endothelial cells and participates in the maintenance of vascular tone. NO is also known to participate in other physiological processes, such as cell survival, proliferation, and migration. The bioavailability of NO is reduced in EPCs from DM-2 patients. Interestingly, an inverse relationship exists between the reduction in NO bioavailability in EPCs and the patients plasma glucose and glycated haemoglobin levels. In addition, NO bioavailability in EPCs correlates with plasma oxidized low-density lipoprotein levels in DM-2. Although this reduction in NO bioavailability could be attributed to oxidative stress in DM-2 patients, it also may be due to impairment of one or more members of the protein signalling cascades that are responsible for NO production. The stimulation of NO production or its signalling cascades in EPCs may increase their numbers and improve their function, thus attenuating endothelium damage, independent of the vasodilatory effects of NO. This review summarizes the metabolic alterations that underlie the molecular mechanisms that may be responsible for EPC decrease and dysfunction in DM-2 with emphasis on the involvement of the NO system.

Nitric oxide and superoxide dismutase modulate endothelial progenitor cell function in type 2 diabetes mellitus

BackgroundThe function of endothelial progenitor cells (EPCs), which are key cells in vascular repair, is impaired in diabetes mellitus. Nitric oxide (NO) and reactive oxygen species can regulate EPC functions. EPCs tolerate oxidative stress by upregulating superoxide dismutase (SOD), the enzyme that neutralizes superoxide anion (O2-). Therefore, we investigated the roles of NO and SOD in glucose-stressed EPCs.MethodsThe functions of circulating EPCs from patients with type 2 diabetes were compared to those from healthy individuals. Healthy EPCs were glucose-stressed, and then treated with insulin and/or SOD. We assessed O2- generation, NO production, SOD activity, and their ability to form colonies.ResultsEPCs from diabetic patients generated more O2-, had higher NAD(P)H oxidase and SOD activity, but lower NO bioavailability, and expressed higher mRNA and protein levels of p22-phox, and manganese SOD and copper/zinc SOD than those from the healthy individuals. Plasma glucose and HbA1c levels in the diabetic patients were correlated negatively with the NO production from their EPCs. SOD treatment of glucose-stressed EPCs attenuated O2- generation, restored NO production, and partially restored their ability to form colonies. Insulin treatment of glucose-stressed EPCs increased NO production, but did not change O2- generation and their ability to form colonies. However, their ability to produce NO and to form colonies was fully restored after combined SOD and insulin treatment.ConclusionOur data provide evidence that SOD may play an essential role in EPCs, and emphasize the important role of antioxidant therapy in type 2 diabetic patients.

Microparticles and pregnancy complications

Microparticles (MPs) are shed from cell membranes of a variety of cells, promote thrombus formation, mediate pro-inflammatory effects and may cause endothelial dysfunction. Normal pregnancy is characterized by increased levels of MPs compared to non-pregnant healthy women but the prevalence, cell origin and the role of MPs in pregnancy-related complications remain controversial. Normal pregnancy is an acquired hyper-coagulable state due to an increase in procoagulants and decrease in natural anticoagulants. Pregnancy-related complications such as preeclampsia, intrauterine fetal growth restriction (IUGR) and fetal loss are associated with placental dysfunction and may cause significant maternal and fetal morbidity and mortality. This article highlights the role of microparticles in maternal placental crosstalk and the interplay between microparticles, thrombosis and pregnancy complications.

Cryogenic Transmission Electron Microscopy Nanostructural Study of Shed Microparticles

Microparticles (MPs) are sub-micron membrane vesicles (100–1000 nm) shed from normal and pathologic cells due to stimulation or apoptosis. MPs can be found in the peripheral blood circulation of healthy individuals, whereas elevated concentrations are found in pregnancy and in a variety of diseases. Also, MPs participate in physiological processes, e.g., coagulation, inflammation, and angiogenesis. Since their clinical properties are important, we have developed a new methodology based on nano-imaging that provides significant new data on MPs nanostructure, their composition and function. We are among the first to characterize by direct-imaging cryogenic transmitting electron microscopy (cryo-TEM) the near-to-native nanostructure of MP systems isolated from different cell types and stimulation procedures. We found that there are no major differences between the MP systems we have studied, as most particles were spherical, with diameters from 200 to 400 nm. However, each MP population is very heterogeneous, showing diverse morphologies. We investigated by cryo-TEM the effects of standard techniques used to isolate and store MPs, and found that either high-g centrifugation of MPs for isolation purposes, or slow freezing to –80°C for storage introduce morphological artifacts, which can influence MP nanostructure, and thus affect the efficiency of these particles as future diagnostic tools.

Thrombotic complications associated with stem cell transplantation

Thrombotic complications are common in stem cell transplantation (SCT) recipients and endothelial cell injury is a dominant contributing factor to the hemostatic impairments. Endothelial cells line the vascular bed and each vascular bed has a unique structural and functional properties. Therefore, understanding of these properties may hold important clues to site-specific diagnostics and therapeutics. The two most common thrombotic manifestations related to SCT, veno-occlusive disease (VOD) and thrombotic microangiopathy (TMA), are characterized by small vessel thrombosis in the microcirculation. In diffuse alveolar hemorrhage (DAH), although the clinical presentation is hemorrhagic, autopsy findings and mice experiments imply a thrombotic etiology. In the present review, the pathogenesis and treatment options of these three microcirculation thromboses are discussed.