A ação combinada da carbonatação e dos cloretos: avaliação do coeficiente de difusão de cloretos em betões carbonatados

Dissertação de mestrado Internacional em Sustentabilidade do Ambiente Construído

Reduction in left ventricular hypertrophy in hypertensive patients treated with enalapril, losartan or the combination of enalapril and losartan

OBJECTIVE: To compare the regression of left ventricular hypertrophy in patients with moderate hypertension treated with enalapril, losartan or a combination of the two drugs at lower doses. METHODS: Patients of both sexes with moderate hypertension confirmed by ambulatory monitoring of arte-rial blood pressure and with left ventricular hypertrophy on echocardiogram were assigned to three groups: enalapril (35 mg/day, n=15), losartan (175 mg/day, n=15) and enalapril+losartan (15 mg+100 mg/day, n=16). The patients received the drugs for 10 months. RESULTS: The three therapeutic regimens were equally effective in reducing blood pressure and left ventricular mass index (LVMI, g/m²): 141±3.9 to 123±3.6 in the enalapril group (p<0.05), from 147±3.8 to 133±2.8 in the losartan group (p<0.05), and from 146±3.0 to 116±4.0 in the enalapril+losartan group (p<0.05). However, the percent reduction of LVMI was significantly greater (p<0.01) in the enalapril+losartan group (20.5±5.0%) than in enalapril (12.4±3.2%) and the losartan (9.1±2.1%) groups. Normalization of LVMI was obtained in 10 out of the 16 patients who received enalapril+ losartan, in 6 out of the 15 patients who received only enalapril and in 4 out of the 15 patients treated with losartan. CONCLUSION: The combination of an angiotensin-converting enzyme inhibitor and an angiotensin II receptor antagonist (AT1 receptor antagonist) in patients produced an additional effect on the reduction of left ventricular hypertrophy. This finding may depend on a more complete inhibition of the cardiac renin-angiotensin.

Reduction of QTc interval dispersion. Potential mechanism of cardiac protection of pyridostigmine bromide

OBJECTIVE: Parasympathetic dysfunction is an independent risk factor in individuals with coronary artery disease, and cholinergic stimulation is a potential therapeutical option. We determined the effects of pyridostigmine bromide, a reversible anticholinesterase agent, on electrocardiographic variables of healthy individuals. METHODS: We carried out a cross-sectional, double blind, randomized, placebo-controlled study. We obtained electrocardiographic tracings in 12 simultaneous leads of 10 healthy young individuals at rest before and after oral administration of 45 mg of pyridostigmine or placebo. RESULTS: Pyridostigmine increased RR intervals (before: 886±27 ms vs after: 1054±37 ms) and decreased QTc dispersion (before: 72±9ms vs after: 45±3ms), without changing other electrocardiographic variables (PR segment, QT interval, QTc, and QT dispersion). CONCLUSION: Bradycardia and the reduction in QTc dispersion induced by pyridostigmine may effectively represent a protective mechanism if these results can be reproduced in individuals with cardiovascular diseases.

PANDORA - Survey of Brazilian cardiologists about cholesterol reduction

OBJECTIVE: To report about a group of physicians' understanding of the recommendations of the II Brazilian Guidelines Conference on Dyslipidemias, and about the state of the art of primary and secondary prevention of atherosclerosis. METHODS: Through the use of a questionnaire on dyslipidemia, atherosclerosis prevention, and recommendations for lipid targets established by the II Brazilian Guidelines Conference on Dyslipidemias, 746 physicians, 98% cardiologists, were evaluated. RESULTS:Eighty-seven percent of the respondents stated that the treatment of dyslipidemia changes the natural history of coronary disease. Although most of the participants followed the total cholesterol recommendations (<200mg/dL for atherosclerosis prevention), only 55.8% would adopt the target of LDL-C <100 mg/dL for secondary prevention. Between 30.5 and 36.7% answered, in different questions, that the recommended level for HDL-C should be <35mg/dL. Only 32.7% would treat their patients indefinitely with lipid- lowering drugs. If the drug treatment did not reach the proposed target, only 35.5% would increase the dosage, and 29.4% would change the medication. Participants did not know the targets proposed for diabetics. CONCLUSION: Although the participating physicians valued the role played by lipids in the prevention of atherosclerosis, serious deficiencies exist in their knowledge of the recommendations given during the II Brazilian Guidelines Conference on Dyslipidemias.

Clinical significance of in-hospital reocclusion after mechanical reperfusion and percutaneous transluminal coronary angioplasty for acute myocardial infarction

OBJECTIVE: To analyze the effects of in-hospital reocclusion of reperfused AMI culprit coronary arteries in mortality and to identify the predictors. METHODS: The present study comprises a sample of 155 patients with AMI who underwent successful mechanical reperfusion by direct coronary angioplasty and angiographic control during hospitalization or before discharge. Patients were classified into group A: reoccluded patients (n=30) and group B: non-reoccluded patients (n=125). RESULTS: We identified in-hospital reocclusion predictors and found a greater significance in mortality among reoccluded patients (23,3% x 1.6%; p=0.00004). Silent reocclusion or typical angina at reocclusion had a good prognosis. The independent predictors of in-hospital mortality were hypertension, multiarterial lesions, totally occluded AMI culprit lesions, failed redilatation, failed redilatation in comparison with no intention to redilate, no redilatation in comparison with no atempt to redilate, and reocclusion within the first 48 to 72 hours. The decision to redilate, independently of the result, led to a 50.0% reduction in hospital mortality (p=0.0366). CONCLUSION: In-hospital AMI culprit coronary artery reocclusion had an adverse effect similar to that reported in clinical studies with high mortality rates (23.3% x 1.6%; p=0.00004). The major contribution of this study is to recommend the reopening of reoccluded AMI culprit coronary arteries as a means for the management of coronary artery reocclusion.

Alcohol and atherosclerosis

Observational studies have attributed a protective effect to alcohol consumption on the development of atherosclerosis and cardiovascular morbidity and mortality. Alcohol intake in the amount of one to two drinks per day results in an estimated 20-40% reduction in cardiovascular events. An additional protective effect, according to major cohort studies, has been attributed to wine, probably due to antioxidant effects and platelet antiaggregation agents. On the other hand, the influence of different patterns of alcohol consumption and environmental factors may explain a great part of the additional effect of wine. Protection may be mediated by modulation of other risk factors, because alcohol increases HDL-C, produces a biphasic response on blood pressure, and modulates the endothelial function, while it neither increases body weight nor impairs glucose-insulin homeostasis. Alcohol may also have a direct effect on atherogenesis. Despite these favorable effects, the current evidence is not enough to justify prescribing alcohol to prevent cardiovascular disease.

Bacterial cellulose-lactoferrin as an antimicrobial edible packaging

Bacterial cellulose (BC) films from two distinct sources (obtained by static culture with Gluconacetobacter xylinus ATCC 53582 (BC1) and from a commercial source (BC2)) were modified by bovine lactoferrin (bLF) adsorption. The functionalized films (BC+bLF) were assessed as edible antimicrobial packaging, for use in direct contact with highly perishable foods, specifically fresh sausage as a model of meat products. BC+bLF films and sausage casings were characterized regarding their water vapour permeability (WVP), mechanical properties, and bactericidal efficiency against two food pathogens, Escherichia coli and Staphylococcus aureus. Considering their edibility, an in vitro gastrointestinal tract model was used to study the changes occurring in the BC films during passage through the gastrointestinal tract. Moreover, the cytotoxicity of the BC films against 3T3 mouse embryo fibroblasts was evaluated. BC1 and BC2 showed equivalent density, WVP and maximum tensile strength. The percentage of bactericidal efficiency of BC1 and BC2 with adsorbed bLF (BC1+bLF and BC2+bLF, respectively) in the standalone films and in inoculated fresh sausages, was similar against E. coli (mean reduction 69 % in the films per se versus 94 % in the sausages) and S. aureus (mean reduction 97 % in the films per se versus 36 % in the case sausages). Moreover, the BC1+bLF and BC2+bLF films significantly hindered the specific growth rate of both bacteria. Finally, no relevant cytotoxicity against 3T3 fibroblasts was found for the films before and after the simulated digestion. BC films with adsorbed bLF may constitute an approach in the development of bio-based edible antimicrobial packaging systems.

Reduction in diastolic blood pressure and cardiovascular mortality in nondiabetic hypertensive patients. A reanalysis of the HOT study

OBJECTIVE: To use published Hypertension Optimal Treatment (HOT) Study data to evaluate changes in cardiovascular mortality in nondiabetic hypertensive patients according to the degree of reduction in their diastolic blood pressure. METHODS: In the HOT Study, 18,700 patients from various centers were allocated at random to groups having different objectives of for diastolic blood pressure: <=90 (n=6264); <=85 (n=6264); <=80mmHg (n=6262). Felodipine was the basic drug used. Other antihypertensive drugs were administered in a sequential manner, aiming at the objectives of diastolic blood pressure reduction. RESULTS: The group of nondiabetic hypertensive subjects with diastolic pressure<=80mmHg had a cardiovascular mortality ratio of 4.1/1000 patients/year, 35.5% higher than the group with diastolic pressure <=90mmHg (cardiovascular mortality ratio, 3.1/1000 patients/year). In contrast, diabetic patients allocated to the diastolic pressure objective group of <=80mmHg had a 66.7% reduction in cardiovascular mortality (3.7/1000 patients/year) when compared with the diastolic pressure group of <=90mmHg (cardiovascular mortality ratio, 11.1/1000 patients/year). CONCLUSION: The results indicate that in hypertensive diabetic patients reduction in diastolic blood pressure to levels <=80mmHg decreases the risk of fatal cardiovascular events. It remains necessary to define the level of diastolic blood pressure <=90mmHg at which maximal reduction in cardiovascular mortality is obtained for nondiabetics.

The role of monocarboxylate transporters in 3-bromopyruvate effect in cancer cells

Tese de Doutoramento em Biologia Molecular e Ambiental (área de especialização em Biologia Molecular e Saúde).

Anaerobic oxidation of methane associated with sulfate reduction in a natural freshwater gas source

The occurrence of anaerobic oxidation of methane (AOM) and trace methane oxidation (TMO) was investigated in a freshwater natural gas source. Sediment samples were taken and analyzed for potential electron acceptors coupled to AOM. Long-term incubations with 13C-labeled CH4 (13CH4) and different electron acceptors showed that both AOM and TMO occurred. In most conditions, 13C-labeled CO2 (13CO2) simultaneously increased with methane formation, which is typical for TMO. In the presence of nitrate, neither methane formation nor methane oxidation occurred. Net AOM was measured only with sulfate as electron acceptor. Here, sulfide production occurred simultaneously with 13CO2 production and no methanogenesis occurred, excluding TMO as a possible source for 13CO2 production from 13CH4. Archaeal 16S rRNA gene analysis showed the highest presence of ANME-2a/b (ANaerobic MEthane oxidizing archaea) and AAA (AOM Associated Archaea) sequences in the incubations with methane and sulfate as compared with only methane addition. Higher abundance of ANME-2a/b in incubations with methane and sulfate as compared with only sulfate addition was shown by qPCR analysis. Bacterial 16S rRNA gene analysis showed the presence of sulfate-reducing bacteria belonging to SEEP-SRB1. This is the first report that explicitly shows that AOM is associated with sulfate reduction in an enrichment culture of ANME-2a/b and AAA methanotrophs and SEEP-SRB1 sulfate reducers from a low-saline environment.

Subendocardial fibrosis in remote myocardium results from reduction of coronary driving pressure during acute infarction in rats

OBJECTIVE: To investigate the role of hemodynamic changes occurring during acute MI in subsequent fibrosis deposition within non-MI. METHODS: By using the rat model of MI, 3 groups of 7 rats each [sham, SMI (MI <30%), and LMI (MI >30%)] were compared. Systemic and left ventricular (LV) hemodynamics were recorded 10 minutes before and after coronary artery ligature. Collagen volume fraction (CVF) was calculated in picrosirius red-stained heart tissue sections 4 weeks later. RESULTS: Before surgery, all hemodynamic variables were comparable among groups. After surgery, LV end-diastolic pressure increased and coronary driving pressure decreased significantly in the LMI compared with the sham group. LV dP/dt max and dP/dt min of both the SMI and LMI groups were statistically different from those of the sham group. CVF within non-MI interventricular septum and right ventricle did not differ between each MI group and the sham group. Otherwise, subendocardial (SE) CVF was statistically greater in the LMI group. SE CVF correlated negatively with post-MI systemic blood pressure and coronary driving pressure, and positively with post-MI LV dP/dt min. Stepwise regression analysis identified post-MI coronary driving pressure as an independent predictor of SE CVF. CONCLUSION: LV remodeling in rats with MI is characterized by predominant SE collagen deposition in non-MI and results from a reduction in myocardial perfusion pressure occurring early on in the setting of MI.

Experimental and model-based analysis of the steady-state and dynamic operating behaviour of the direct methanol fuel cell (DMFC)

Direct methanol fuel cell, DMFC, model, mass transport, Maxwell-Stefan, Flory-Huggins, crossover, polymer electrolyte membrane, Nafion

Direct numerical simulation of turbulent flames on parallel computers

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2012

Lipoprotein (a): Structure, Pathophysiology and Clinical Implications

The chemical structure of lipoprotein (a) is similar to that of LDL, from which it differs due to the presence of apolipoprotein (a) bound to apo B100 via one disulfide bridge. Lipoprotein (a) is synthesized in the liver and its plasma concentration, which can be determined by use of monoclonal antibody-based methods, ranges from < 1 mg to > 1,000 mg/dL. Lipoprotein (a) levels over 20-30 mg/dL are associated with a two-fold risk of developing coronary artery disease. Usually, black subjects have higher lipoprotein (a) levels that, differently from Caucasians and Orientals, are not related to coronary artery disease. However, the risk of black subjects must be considered. Sex and age have little influence on lipoprotein (a) levels. Lipoprotein (a) homology with plasminogen might lead to interference with the fibrinolytic cascade, accounting for an atherogenic mechanism of that lipoprotein. Nevertheless, direct deposition of lipoprotein (a) on arterial wall is also a possible mechanism, lipoprotein (a) being more prone to oxidation than LDL. Most prospective studies have confirmed lipoprotein (a) as a predisposing factor to atherosclerosis. Statin treatment does not lower lipoprotein (a) levels, differently from niacin and ezetimibe, which tend to reduce lipoprotein (a), although confirmation of ezetimibe effects is pending. The reduction in lipoprotein (a) concentrations has not been demonstrated to reduce the risk for coronary artery disease. Whenever higher lipoprotein (a) concentrations are found, and in the absence of more effective and well-tolerated drugs, a more strict and vigorous control of the other coronary artery disease risk factors should be sought.

System-oriented analysis of the dynamic behaviour of direct methanol fuel cells

DMFC, dynamic behaviour, current steps, system analysis, methanol oxidation, flow field design