OBJECTIVE:Epoxyeicosatrienoic acids (EETs) act as vasodilators activating high conductance calcium-operated potassium (K) channels (Kca1.1, also named BK, MAXI-K). We found expression of MAXI-K ...channel in platelets. The present study aimed at defining its functionality in platelet using an in vitro model of platelet thrombosis.
DESIGN AND METHOD:We tested the effects of 5 μmol/L 11,12-EET and the pharmacological modulation of MAXI-K channel (agonists5 and 20 μmol/L BMS 191011, 5 μmol/L NS1619, 5 μmol/L NS11021). Platelet rich plasma was used to assess adhesion-induced thrombi formation under flow by microfluidics technology with collagen-coated microchips mimicking arterial blood flow. The kinetic of platelet responses to scalar doses of 0.3–10 μmol/L ADP, 0.05–2 μmol/L U46619 0.5–10 μg/mL collagen was determined by paired analysis using Born aggregometry. Flow-cytometry was used to analyse the expression of active fibrinogen receptor and P-selectin in stimulated platelets. The effects of 100 μmol/L aspirin and 1 μmol/L ticagrelor were also assessed.
RESULTS:In vitro thrombi formation was halved (expressed as platelet-covered area) by pre-treatment with either 11,12-EET (−45 ± 11%, n = 5, P < 0.001 vs control, Mean ± SD), aspirin (−66 ± 8%, n = 4, P < 0.001) or ticagrelor (−55 ± 8%, n = 4, P < 0.001). Similar results were obtained using BMS 5 μmol/L (−54 ± 17%, n = 6, P < 0.001), NS1619 (−50 ± 19%, n = 9, P < 0.001), NS11021 (−60 ± 21%, n = 6, P < 0.001). The addition of 20 μmol/L BMS191011 prior to platelet aggregation (EC502.67 μmol/L, 95%CI0.97–7.29, n = 36) significantly shifted to the right the dose response-curve to ADP (EC500.91 μmol/L, 0.43–1.92, n = 36). Platelet aggregation was further blunted by the addition of aspirin to BMS191011 (EC506.18 μmol/L, 2.11–18.09, n = 36). U46619- and collagen-induced aggregation was not altered. ADP-induced activation of the fibrinogen receptor (−48 ± 14% to −62 ± 10%, n = 7, P < 0.05) and P-selectin expression (−37 ± 15% to −41 ± 13%, n = 7, P < 0.01) were blunted by the activators of MAXI-K channel.
CONCLUSIONS:Activation of the MAXI-K channel by 11,12-EET and all the tested synthetic compounds is associated with reduced sensitivity to ADP and reduced thrombus generation through the inhibition of the amplificatory phase of platelet activation. The present results reveal new mechanisms of platelet activation and suggest that targeting MAXI-K might be of potential pharmacological interest for the prevention of atherothrombosis.
The Sinos River basin is located Northeast of the state of Rio Grande do Sul (29º 20' to 30º 10' S and 50º 15' to 51º20'W), Southern Brazil, covering two geomorphologic provinces: the Southern ...plateau and central depression. It is part of the Guaíba basin and has an area of approximately 800 km², encompassing 32 municipalities. The objective of this study was to monitor water quality in the Sinos River, the largest river in this basin. Water samples were collected at four selected sites in the Sinos River, and the following parameters were analysed: pH, dissolved oxygen, biochemical oxygen demand (BOD₅), turbidity, fecal coliforms, total dissolved solids, temperature, nitrate, nitrite, phosphorous, chromium, lead, aluminum, zinc, iron, and copper. The results were analysed based on Resolution No. 357/2005 of the Brazilian National Environmental Council (CONAMA) regarding regulatory limits for residues in water. A second analysis was performed based on a water quality index (WQI) used by the Sinos River Basin Management Committee (COMITESINOS). Poor water quality in the Sinos River presents a worrying scenario for the region, since this river is the main source of water supply for the urban core. Health conditions found in the Sinos River, mainly in its lower reaches, are worrying and a strong indicator of human activities on the basin.
The discharge of sewage and industrial effluents containing high concentrations of pollutants in water bodies increases eutrophication. Cyanobacteria, some of the organisms whose growth is promoted ...by high nutrient concentrations, are resistant and produce several types of toxins, known as cyanotoxins, highly harmful to human beings. Current water treatment systems for the public water supply are not efficient in degradation of toxins. Advanced oxidation processes (AOP) have been tested for the removal of cyanotoxins, and the results have been positive. This study examines the application of photoelectrooxidation in the degradation of cyanotoxins (microcystins). The performance of the oxidative processes involved was evaluated separately: Photocatalysis, Electrolysis and Photoelectrooxidation. Results showed that the electrical current and UV radiation were directly associated with toxin degradation. The PEO system is efficient in removing cyanotoxins, and the reduction rate reached 99%. The final concentration of toxin was less than 1 µg/L of microcystin in the treated solution.
Nowadays, the conventional tannery wastewater treatment is not established in order to obtain water in such a quality that it could be reused in the same process. This study was then carried out in ...order to study an integrated wastewater treatment system, membrane bioreactor–photoelectrooxidation (MBR–PEO), for the final polishing of tannery wastewater. MBR is responsible for the remaining biochemical oxygen demand removal, while the refractory matter, quantified as chemical oxygen demand, is removed by PEO. This treatment configuration has provided two wastewater streams with quality standards for reuse as process water. The wastewater treated by the MBR could be reused in beamhouse operations, while the wastewater treated by the integrated MBR–PEO processes could be recycled for the tanyard and re-tanning steps due to its appreciable quality.
Background: Thromboembolism is a relatively common complication of chronic heart failure (HF) and the place of antiplatelet therapy is uncertain. Objectives: We characterized the rate of thromboxane ...and prostacyclin biosynthesis in chronic HF of ischemic origin, with the aim of separating the influence of HF on platelet activation from that of the underlying ischemic heart disease (IHD). Patients and Methods: We compared urinary 11‐dehydro‐thromboxane (TX)B2, 2,3 dinor 6‐keto‐PGF1α, 8‐iso‐prostaglandin (PG)F2α, and plasma N‐terminal pro‐brain natriuretic peptide (NT‐pro‐BNP), asymmetric dimethylarginine (ADMA), and soluble CD40 ligand (sCD40L), in 84 patients with HF secondary to IHD, 61 patients with IHD without HF and 42 healthy subjects. Results: HF patients not on aspirin had significantly higher urinary 11‐dehydro‐TXB2 as compared with healthy subjects (P < 0.0001) and IHD patients not on aspirin (P = 0.028). They also showed significantly higher 8‐iso‐PGF2α (P = 0.018), NT‐pro‐BNP (P = 0.021) and ADMA (P < 0.0001) than IHD patients not on aspirin. HF patients on low‐dose aspirin had significantly lower 11‐dehydro‐TXB2 (P < 0.0001), sCD40L (P = 0.007) and 2,3‐dinor‐6‐keto‐PGF1α (P = 0.005) than HF patients not treated with aspirin. HF patients in NYHA classes III and IV had significantly higher urinary 11‐dehydro‐TXB2 than patients in classes I and II, independently of aspirin treatment (P < 0.05). On multiple linear regression analysis, higher NT‐pro‐BNP levels, lack of aspirin therapy and sCD40L, predicted 11‐dehydro‐TXB2 excretion rate in HF patients (R2 = 0.771). Conclusions: Persistent platelet activation characterizes HF patients. This phenomenon is related to disease severity and is largely suppressable by low‐dose aspirin. The homeostatic increase in prostacyclin biosynthesis is impaired, possibly contributing to enhanced thrombotic risk in this setting.
The aim of this work is to compare the protection against corrosion imparted by different conducting polymers when these materials are used as anticorrosive additives in the formulation of ...conventional epoxy paints. Specifically, the polymers employed as anticorrosive additives are polyaniline emeraldine salt, polyaniline emeraldine base, polyaniline emeraldine salt composite with carbon black, polypyrrole composite with carbon black and poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulphonate). Initially, the structural, thermal and mechanical properties of the unmodified epoxy paint as well as the modified coatings, obtained by the addition of 0.3 wt.% of conducting polymers, have been characterized. After this, controlled accelerated corrosion assays in an aggressive solution medium were developed using coated steel panels. Results indicate that the protection against corrosion imparted by the formulations modified by the addition of poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulphonate), polyaniline emeraldine salt and, especially, polyaniline emeraldine base is significantly higher than that of the unmodified paint. In contrast, the use of conducting polymer composite with carbon black reduces the efficacy of the coating. Results indicate that some conducting polymer compositions should be considered as a suitable alternative to replace inorganic anticorrosive pigments currently used in paint formulations.
Langmuir-type films of poly(5-arnino-l-naphthol) conductive polymer were formed at the air/water interface. The surface pressure versus molecular area isotherms of the polymeric layers showed a high ...tendency to aggregate and non-monomolecular behavior on the water surface. Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) procedures have been successfully used to transfer the Langmuir films of this polymer onto hydrophilic silicon substrates. Atomic force microscopy images showed that the films obtained by the LS method have much better quality than those obtained by the LB one. In particular, we have obtained uniform and smooth LS films covering practically all the substrate, while the LB films showed rather aggregated material, only partially covering the substrate.
The electrodeposition of poly(5-amino-1-naphthol) films on mild steel from aqueous perchloric acid is reported. The polymer films are very adherent to the surface and present the same structure as in ...the case of Pt electrode. The test for corrosion protection of the polymer-coated iron samples was done in acidic solutions (0.4
M NaCl+0.1
M HCl).
Atomic force microscopy (AFM) was used to investigate ultrathin films of poly (5-amino-1-naphthol) (PAN) deposited by Langmuir–Schaefer (LS) and Langmuir–Blodgett (LB) on silicon substrates. The AFM ...probe was also used to perform nano-indentation and nano-delamination of the polymeric film. By measuring the applied vertical force at the beginning of the delamination process and by using an appropriate model for micro-indentation of elastic continuous systems, we estimate the critical interfacial shear strength for the PAN/Si interface as being approximately 160
MPa, which indicates that the polymer adheres well to the substrate. The conditions to obtain multiple depositions of the polymeric film on Si substrates are also described. The multilayer PAN films obtained by associating the LS and LB methods were very smooth and uniform, with approximately 5
nm/monolayer.
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