Evaluation of New Potential Inflammatory Markers in Patients with Nonvalvular Atrial Fibrillation.

Atrial fibrillation (AF), the most common arrhythmia in clinical practice, is associated with an increase in mortality and morbidity due to its high potential to cause stroke and systemic thromboembolism. Inflammatory mechanisms may play a role in the pathogenesis of AF and its maintenance. We aimed to evaluate a range of inflammatory markers as potentially involved in the pathophysiology of individuals with nonvalvular AF (NVAF). A total of 105 subjects were enrolled and divided into two groups: patients with NVAF (n = 55, mean age 72 ± 8 years) and a control group of individuals in sinus rhythm (n = 50, mean age 71 ± 8 years). Inflammatory-related mediators were quantified in plasma samples by using Cytometric Bead Array and Multiplex immunoassay. Subjects with NVAF presented significantly elevated values of interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF), interferon-gamma, growth differentiation factor-15, myeloperoxidase, as well as IL-4, interferon-gamma-induced protein (IP-10), monokine induced by interferon-gamma, neutrophil gelatinase-associated lipocalin, and serum amyloid A in comparison with controls. However, after multivariate regression analysis adjusting for confounding factors, only IL-6, IL-10, TNF, and IP-10 remained significantly associated with AF. We provided a basis for the study of inflammatory markers whose association with AF has not been addressed before, such as IP-10, in addition to supporting evidence about molecules that had previously been associated with the disease. We expect to contribute to the discovery of markers that can be implemented in clinical practice hereafter.

Chronic Lymphocytic Leukemia (CLL): evaluation of AKT protein kinase and microRNA gene expression related to disease pathogenesis

Abstract The present study evaluated 56 patients diagnosed with Chronic Lymphocytic Leukemia (CLL) and a control group of 44 clinically healthy subjects with no previous history of leukemia. Genetic expressions of AKT and microRNAs were evaluated by quantitative PCR (qPCR). A significant increase in AKT gene expression in patients when compared to controls was observed (p = 0.017). When the patients were stratified according to Binet subgroups, a significant difference was observed between the subgroups, with this protein kinase appearing more expressed in the B+C subgroup (p = 0.013). Regarding miRNA expression, miR-let-7b and miR-26a were reduced in CLL patients, when compared to controls. However, no significant differences were observed in these microRNA expressions between the Binet subgroups (A versus B+C). By contrast, miR-21 to miR-27a oncogenes showed no expression difference between CLL patients and controls. AKT protein kinase is involved in the signaling cascade that occurs with BCR receptor activation, leading to increased lymphocyte survival and protection against the induction of cell death in CLL. Thus, increased AKT protein kinase expression and the reduction of miR-let-7b and miR-26a, both tumor suppressors, may explain increased lymphocyte survival in CLL patients and may be promising markers for the prognostic evaluation of this disease.

Atrial Fibrillation and Use of Rivaroxaban: Performance of the Prothrombin Time / INR as a Function of Time After Blood Collection

Abstract Background Traditionally, the most effective therapy in the prevention of stroke in patients with atrial fibrillation (AF) has been oral anticoagulation with vitamin K inhibitors, particularly warfarin, whose disadvantages and adverse effects have led to their replacement by "direct oral anticoagulants", as factor X inhibitor. Objectives This study aimed to conduct a brief approach on atrial fibrillation (AF) and use of Rivaroxaban, and to comparatively evaluate the prothrombin time / International Normalized Ratio (PT/INR) in patients with AF in use of this oral anticoagulant, depending on the time elapsed between the last administration of the drug and the time of blood sample venipuncture. Methods We evaluated 34 patients with AF in use of Rivaroxaban by using PT / INR, distributed into a subgroup with blood collection time ≤ 12 hours (n = 7) and > 12 hours after the last drug intake (n = 27). Mann-Whitney test was used to compare the groups and p < 0.05 was considered significant. Results An analysis as a function of time between the Rivaroxaban intake and blood collection, revealed that PT / INR suffers the greatest effect up to 12 hours after ingestion of the drug, dropping to levels close to normal in subsequent hours before the next dose. Conclusion We concluded that, in contrast to warfarin, the knowledge of the time interval between drug intake and blood collection from patients taking Rivaroxaban is essential to properly interpret a laboratory test to assess hemostasis, particularly PT and its derivatives. Int J Cardiovasc Sci. 2020; [online].ahead print, PP.0-0

Activated platelets in central venous catheters: a flow cytometry and numerical simulation approach

The central venous catheter that is inserted in patients undergoing hemodialysis can cause hemodynamic instability and trigger complications such as thrombus formation. The objective of this study was to investigate hemostatic and numerical influences on thrombus formation in patients undergoing hemodialysis with a central venous catheter. Participants were assigned to three groups: I: clinical and laboratorial healthy individuals matched by sex and age (controls); II: participants after one month of insertion of the catheter and III: participants after 4 months of insertion of the catheter. Platelet activation was investigated by GPIIb/IIIa and p-selectin expressions using flow cytometry. A three-dimensional model of the catheter was constructed in the numerical simulation for the calculation of partial differential equation of a platelet activation model. A significant difference was detected by the expression of p-selectin comparing the group I (33.42 ± 4.74), group II (40.79 ± 5.54) and group III(51.00 ± 7.21) (p < 0.0001). The median values for GPIIb/IIIa were 10426 (10029-10721), 13921 (13412-15652) and 19946 (18714-21815) after catheter insertion (p < 0.0001), for groups I, II and III, respectively. Excluding the first arterial orifice, venous orifices tend to have greater platelet activation when compared to the other arterial orifices. The results of this study showed the influence of arterial and venous lateral orifices in stimulating the development of thrombi associated with the activation of platelet markers the longer the catheter was used.

Standardization and evaluation of the performance of the thrombin generation test under hypo- and hypercoagulability conditions

ABSTRACT Background: In order to standardize a thrombin generation() protocol, we analyzed the analytical variables and sensitivity of this test to hypo/hypercoagulability states. Methods: The effect of the tissue factor concentration and the intra- and interassay precision were analyzed. To evaluate the hypercoagulability status, the plasma of women under an oral contraceptive was tested, while plasma from hemophilia A patients at 1, 3 and 7 days after recombinant FVIII infusion, and lyophilized plasma deficient in FVII or FVIII were used for the evaluation of hypocoagulability. Results: The intra-assay coefficient of variation was <10% with 1 and 5 pM of low and high TF. The oral contraceptive users showed increased thrombin generation in comparison to non-users, which was more pronounced with low TF (endogenous thrombin potential ETP) p = 0.0009; peak p = 0.0009; lagtime p = 0.0008). In relation to the FVIII-deficient plasma, a higher TG was observed as FVIII levels were increased and a better discrimination was obtained for different concentrations of FVIII with low TF (ETP p < 0.0001; peak p < 0.0001; lagtime p = 0.0004). Using low TF, plasma from hemophilia A patients showed higher TG values after 1 day of recombinant FVIII infusion vs after 3 days (ETP p < 0.0001; peak p < 0.0001; lagtime p = 0.0407), while the lowest values were observed after 7 days. With FVII-deficient plasma, thrombin generation was lower than normal plasma and a more pronounced difference was observed with high TF compared to low TF (ETP p < 0.0001; peak p < 0.0001; lagtime p < 0.0001). Conclusion: Under our conditions the thrombin generation test seems to be sensitive to evaluation of hyper/hypocoagulability states. Standardization of the thrombin generation test may have an application in the evaluation of bleeding and thrombotic disorders.

Thrombin generation assays for global evaluation of the hemostatic system: perspectives and limitations

Abstract The existing techniques to evaluate hemostasis in clinical laboratories are not sensitive enough to detect hypercoagulable and mild hypocoagulable states. Under different experimental conditions, the thrombin generation test may meet these requirements. This technique evaluates the overall balance between procoagulant and anticoagulant forces and has provided new insights in our understanding of the coagulation cascade, as well as of the diagnosis of hypocoagulability and hypercoagulability conditions. Thrombin generated in the thrombin generation test can be quantified as platelet-rich or platelet-poor plasma using the calibrated automated thrombogram method, which monitors the cleavage of a fluorogenic substrate that is simultaneously compared to the known thrombin activity in a non-clotting plasma sample. The calibrated automated thrombogram method is an open system, in which different antibodies, proteins, enzymes and peptides can be introduced to answer specific questions regarding hemostatic processes. The thrombin generation test has great clinical potential, such as in monitoring patients taking anticoagulants and antiplatelet drugs, screening for genetic or acquired thrombotic disorders, and evaluating bleeding risk control in patients with hemophilia using bypass agents or replacement therapy. Different to conventional coagulation tests, the thrombin generation test can be used for an overall evaluation of hemostasis, the results of which can then be used to evaluate specific characteristics of hemostasis, such as prothrombin time, activated partial thromboplastin time, and levels of fibrinogen and other coagulation factors. The introduction of this method will contribute to a better understanding and evaluation of overall hemostatic processes; however, this method still requires standardization and clinical validation.

Acetylsalicylic acid therapy: influence of metformin use and other variables on urinary 11-dehydrothromboxane B2 levels.

BACKGROUND: The effect of acetylsalicylic acid (ASA) may be measured through the analysis of urinary concentrations of 11-dehydrothromboxane B2 (11-dhTXB2), a metabolite of thromboxane A2, which is a potent platelet aggregant agent. It has been suggested that metformin (an oral antidiabetic drug) could improve oxidative stress and control platelet activation in type 2 diabetic patients, potentially reducing cardiovascular risk. We determined the concentrations of urinary 11-dhTXB2 in type 2 diabetic patients taking ASA and its concentrations with metformin use and several other clinical variables (hypertension, age, gender, smoking, body mass index, insulin and statin use), considering a reduction of at least 75% in the concentrations of this marker as a target, compared to results before ASA intake. METHODS: Urinary concentrations of 11-dhTXB2 of 81 type 2 diabetic patients were measured before and at 15 days taking 100 mg of aspirin daily. RESULTS: Most patients who presented a reduction of 11-dhTXB2 above 75% were under metformin use. This reduction was achieved in 51.5% of patients taking this drug, against 20.0% in the patients who were not (p=0.027). The analysis of the other variables did not show a significant difference. The use of metformin appears to play a role in the reduction of 11-dhTXB2 concentrations in type 2 diabetic patients. CONCLUSION: According to previous reports, hyperglycemia control seems to be a determinant factor for the success of ASA therapy, given the influence of metformin in the reduction of 11-dhTXB2 concentrations.