Aline Barnabé

Increased ADAMTS13 activity in patients with venous thromboembolism

Increased levels of inflammatory markers and clotting factors have been related to the pathogenesis and prognosis of venous thromboembolism. In particular, the imbalance between VWF and ADAMTS13 has been described in patients with arterial thrombosis. In this study, 77 patients with previous VTE and 77 matched controls were selected for the evaluation of the inflammatory markers, FVW, ADAMTS 13 and D-dimer. The presences of post-thrombotic syndrome and residual vein obstruction were also assessed in patients. Serum levels of TNF-α and IL-6 were significantly increased in patients compared to controls (median=2.25 vs 1.59 pg/mL, P ≤ 0.001; 1.16 vs 0.98 pg/ml, P=0.013, respectively). Plasma levels and activity of VWF (median=150.25 vs 95.39 U/dL, P ≤ 0.001; 145.26% vs 92.39%, P ≤ 0.001) and ADAMTS 13 (median=1088.84 vs 950.80 ng/mL, P ≤ 0.001; 96.03 vs 83.64%, P ≤ 0.001) were also higher in patients. We further analysed the subgroups of patients with higher risk for VTE recurrence or VTE sequelae, defined as the presence of high D-dimer levels, RVO or PTS. All inflammatory markers were significantly higher in patients with increased D-dimer. The presence of PTS or RVO was not associated with higher inflammatory or coagulation parameters. The increased levels of inflammatory markers and VWF may suggest that there is a persistence of inflammatory activity in patients even at long periods after the VTE episode. In this context, it may be postulated that increased levels of ADAMTS13 could represent a compensatory mechanism against persistently increased levels of VWF. Moreover, increased inflammatory activity was associated with increased D-dimer levels, thus it is possible that this inflammatory activity may also be related to the risk of VTE recurrence.

Folate, Vitamin B12 and Homocysteine status in the post-folic acid fortification era in different subgroups of the Brazilian population attended to at a public health care center

BackgroundFolate and vitamin B12 are essential nutrients, whose deficiencies are considerable public health problems worldwide, affecting all age groups. Low levels of these vitamins have been associated with high concentrations of homocysteine (Hcy) and can lead to health complications. Several genetic polymorphisms affect the metabolism of these vitamins. The aims of this study were to assess folate, vitamin B12 and homocysteine status in distinct Brazilian individuals after the initiation of folic acid fortification by Brazilian authorities and to investigate the effects of RFC1 A80G, GCPII C1561T and MTHFR C677T polymorphisms on folate, vitamin B12 and Hcy levels in these populations.MethodsA total of 719 individuals including the elderly, children, as well as pregnant and lactating women were recruited from our health care center. Folate, vitamin B12 and Hcy levels were measured by conventional methods. Genotype analyses of RFC1 A80G, GCPII C1561T and MTHFR C677T polymorphisms were performed by PCR-RFLP.ResultsThe overall prevalence of folate and vitamin B12 deficiencies were 0.3% and 4.9%, respectively. Folate deficiency was observed only in the elderly (0.4%) and pregnant women (0.3%), whereas vitamin B12 deficiency was observed mainly in pregnant women (7.9%) and the elderly (4.2%). Plasma Hcy concentrations were significantly higher in the elderly (33.6%). Pregnant women carrying the MTHFR 677TT genotype showed lower serum folate levels (p = 0.042) and higher Hcy levels (p = 0.003). RFC1 A80G and GCPII C1561T polymorphisms did not affect folate and Hcy levels in the study group. After a multivariate analysis, Hcy levels were predicted by variables such as folate, vitamin B12, gender, age and RFC1 A80G polymorphism, according to the groups studied.ConclusionOur results suggest that folate deficiency is practically nonexistent in the post-folic acid fortification era in the subgroups evaluated. However, screening for vitamin B12 deficiency may be particularly relevant in our population, especially in the elderly.

Increased adhesive properties of neutrophils and inflammatory markers in venous thromboembolism patients with residual vein occlusion and high D-dimer levels

BACKGROUND Venous thromboembolism (VTE) develops via a multicellular process on the endothelial surface. Although widely recognized, the relationship between inflammation and thrombosis, this relationship has been mostly explored in clinical studies by measuring circulating levels of inflammatory cytokines. However, the role of inflammatory cells, such as neutrophils, in the pathogenesis of VTE is not clear in humans. AIMS To evaluate the adhesive properties of neutrophils, erythrocytes and platelets in VTE patients and to correlate findings with inflammatory and hypercoagulability marker levels. METHODS Study group consisted of twenty-nine VTE patients and controls matched according to age, gender and ethnic background. Adhesive properties of neutrophils, erythrocytes and platelets were determined using a static adhesion assay. Neutrophil adhesion molecules expressions were evaluated by flow cytometry. Inflammatory and hypercoagulability marker levels were evaluated by standard methods. Residual vein occlusion (RVO) was evaluated by Doppler ultrasound. RESULTS No significant difference could be observed in platelet and erythrocyte adhesion between VTE patients and controls. Interestingly, VTE patients with high levels of D-dimer and RVO, demonstrated a significant increase in neutrophil adhesion, compared to controls and remaining patients. Inflammatory markers (IL-6, IL-8, TNF-α) were also significantly elevated in this subgroup, compared to other VTE patients. Adhesive properties of neutrophils correlated with IL-6 and D-dimer levels. Neutrophils adhesion molecules (CD11a, CD11b and CD18) were not altered in any of the groups. CONCLUSION These findings not only support the hypothesis of an association between inflammation and hypercoagulability, but more importantly, highlight the role of neutrophils in this process.

Characterization of PCL and Chitosan Nanoparticles as Carriers of Enoxaparin and Its Antithrombotic Effect in Animal Models of Venous Thrombosis

This study was based on the preparation, characterization, and animal in vivo experiments performed to evaluate nanoparticles of poly(ɛ-caprolactone) (PCL) and chitosan as carriers of enoxaparin. The nanoparticles were characterized and presented satisfactory results in terms of size, polydispersity, and encapsulation efficiency. Anticoagulant activity of the nanoparticles was maintained for 14 hours when the administration was subcutaneous; however no activity was observed after oral administration. There was a significant reduction in thrombus size, in vivo, for both free and encapsulated enoxaparin in comparison with the control group after subcutaneous administration. Oral administration results however were indifferent. In conclusion, the double emulsion method w/o/w was efficient for enoxaparin encapsulation, producing spherical nanoparticles with high encapsulation efficiency. For in vivo studies, the encapsulated enoxaparin showed a sustained anticoagulant activity for a higher period of time compared to free enoxaparin, with an antithrombotic effect when administered subcutaneously.