MicroECG: an integrated platform for the cardiac arrythmia detection and characterization

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e Computadores

Damage assessment of fibre reinforced laminates

The use of solid wastes and natural fibres to the production of innovative composites is now a matter of environmental need. A set of hybrid composites constituted of waste rubber particles and sugarcane bagasse fibres into a thermoset composite material are drilled to determine the effect of rubber particle addition and size, sugarcane fibre addition and length and fibre chemical treatment on damage extension and related mechanical properties. Damage extension is determined by enhanced radiography for further damage measurement – diameter and areas – and correlated with mechanical test results — bearing test. The results demonstrated significant effect of the rubber and fibre additions on mechanical properties of the composites.

Acute Bivalvular Left-Sided Methicillin-Resistant Staphylococcus Aureus Endocarditis with Cardiac, Cerebral, Renal and Septic Complications

Infective endocarditis (IE) is now rare in developed countries, but its prevalence is higher in elderly patients with prosthetic valves, diabetes, renal impairment, or heart failure. An increase in health-care associated IE (HCAIE) has been observed due to invasive maneuvers (30% of cases). Methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus are the most common agents in HCAIE, causing high mortality and morbidity. We review complications of IE and its therapy, based on a patient with acute bivalvular left-sided MRSA IE and a prosthetic aortic valve, aggravated by congestive heart failure, stroke, acute immune complex glomerulonephritis, Candida parapsilosis fungémia and death probably due to Serratia marcescens sepsis. The HCAIE was assumed to be related to three temporally associated in-hospital interventions considered as possible initial etiological mechanisms: overcrowding in the hospital environment,iv quinolone therapy and red blood cell transfusion. Later in the clinical course,C. parapsilosis and S. marcescens septicemia were considered to be possible secondary etiological mechanisms of HCAIE.

Cardiac Angiosarcoma. A Review

Based on a case of a patient with angiosarcoma (AS) of the right atrium with superior vena cava syndrome associated with urticaria and polyarthralgias, who died soon after surgery, the authors present a brief review of the subject of cardiac AS, an extremely rare pathology, usually diagnosed late due to its non-specific symptomatology. Several topics are discussed, including mechanisms of clinical manifestations caused by blood flow obstruction and valve dysfunction, local invasion with arrhythmias and pericardial effusion, embolic phenomena and constitutional symptoms. Imaging and histopathologic methods of diagnosis are considered, as well as references to cytogenetic analysis. Surgery is the first treatment choice, but heart AS are frequently not completely resectable and concomitant metastases at the time of surgery are common, both usually leading to a dismal prognosis. Chemotherapy, radiotherapy and even heart transplantation do not substantially improve the survival of these patients. Urticaria is not generally assumed by most authors to be associated with malignancy, but there are rare reports of its association with some malignant tumors.

No Fate But What We Make: a Case of Full Recovery After Out-of-Hospital Cardiac Arrest

An 80 years old man suffered a cardiac arrest shortly after arrival to his local health department. Basic Life Support was started promptly and nine minutes later, on evaluation by an Advanced Life Support team, the victim was defibrillated with a 200J shock. When orotracheal intubation was attempted, masseter muscle contraction was noticed: on reevaluation, the victim had pulse and spontaneous breathing.Thirty minutes later, the patient had been transferred to an emergency department. As he complained of chest pain, the ECG showed a ST segment depression in leads V4 to V6 and laboratory tests showed cardiac troponine I slightly elevated. A coronary angiography was performed urgently: significant left main plus three vessel coronary artery disease was disclosed.Eighteen hours after the cardiac arrest, a quadruple coronary artery bypass grafting operation was undertaken. During surgery, a fresh thrombus was removed from the middle left anterior descendent artery. Post-operative course was uneventful and the patient was discharged seven days after the procedure. Twenty four months later, he remains asymptomatic.In this case, the immediate call for the Advanced Life Support team, prompt basic life support and the successful defibrillation, altogether, contributed for the full recovery. Furthermore, the swiftness in the detection and treatment of the acute reversible cause (myocardial ischemia in this case) was crucial for long-term prognosis.

Effects of Chlorophenoxy Herbicides and Their Main Transformation Products on DNA Damage and Acetylcholinesterase Activity

Persistent pesticide transformation products (TPs) are increasingly being detected among different environmental compartments, including groundwater and surface water. However, there is no sufficient experimental data on their toxicological potential to assess the risk associated with TPs, even if their occurrence is known. In this study, the interaction of chlorophenoxy herbicides (MCPA, mecoprop, 2,4-D and dichlorprop) and their main transformation products with calf thymus DNA by UV-visible absorption spectroscopy has been assessed. Additionally, the toxicity of the chlorophenoxy herbicides and TPs was also assessed evaluating the inhibition of acetylcholinesterase activity. On the basis of the results found, it seems that AChE is not the main target of chlorophenoxy herbicides and their TPs. However, the results found showed that the transformation products displayed a higher inhibitory activity when compared with the parent herbicides. The results obtained in the DNA interaction studies showed, in general, a slight effect on the stability of the double helix. However, the data found for 4-chloro-2-methyl-6-nitrophenol suggest that this transformation product can interact with DNA through a noncovalent mode.

Protective effect of C. sativa leaf extract against UV mediated-DNA damage in a human keratinocyte cell line

Toxic effects of ultraviolet (UV) radiation on skin include protein and lipid oxidation, and DNA damage. The latter is known to play a major role in photocarcinogenesis and photoaging. Many plant extracts and natural compounds are emerging as photoprotective agents. Castanea sativa leaf extract is able to scavenge several reactive species that have been associated to UV-induced oxidative stress. The aim of this work was to analyze the protective effect of C. sativa extract (ECS) at different concentrations (0.001, 0.01, 0.05 and 0.1 μg/mL) against the UV mediated-DNA damage in a human keratinocyte cell line (HaCaT). For this purpose, the cytokinesis-block micronucleus assay was used. Elucidation of the protective mechanism was undertaken regarding UV absorption, influence on 1O2 mediated effects or NRF2 activation. ECS presented a concentration-dependent protective effect against UV-mediated DNA damage in HaCaT cells. The maximum protection afforded (66.4%) was achieved with the concentration of 0.1 μg/mL. This effect was found to be related to a direct antioxidant effect (involving 1O2) rather than activation of the endogenous antioxidant response coordinated by NRF2. Electrochemical studies showed that the good antioxidant capacity of the ECS can be ascribed to the presence of a pool of different phenolic antioxidants. No genotoxic or phototoxic effects were observed after incubation of HaCaT cells with ECS (up to 0.1 μg/mL). Taken together these results reinforce the putative application of this plant extract in the prevention/minimization of UV deleterious effects on skin.

Calcium signaling and the novel anti-proliferative effect of the UTP-sensitive P2Y11 receptor in rat cardiac myofibroblasts

During myocardial ischemia and reperfusion both purines and pyrimidines are released into the extracellular milieu, thus creating a signaling wave that propagates to neighboring cells via membrane-bound P2 purinoceptors activation. Cardiac fibroblasts (CF) are important players in heart remodeling, electrophysiological changes and hemodynamic alterations following myocardial infarction. Here, we investigated the role UTP on calcium signaling and proliferation of CF cultured from ventricles of adult rats. Co-expression of discoidin domain receptor 2 and -smooth muscle actin indicate that cultured CF are activated myofibroblasts. Intracellular calcium ([Ca2+]i) signals were monitored in cells loaded with Fluo-4 NW. CF proliferation was evaluated by the MTT assay. UTP and the selective P2Y4 agonist, MRS4062, caused a fast desensitizing [Ca2+]i rise originated from thapsigargin-sensitive internal stores, which partially declined to a plateau providing the existence of Ca2+ in the extracellular fluid. The biphasic [Ca2+]i response to UTP was attenuated respectively by P2Y4 blockers, like reactive blue-2 and suramin, and by the P2Y11 antagonist, NF340. UTP and the P2Y2 receptor agonist MRS2768 increased, whereas the selective P2Y11 agonist NF546 decreased, CF growth; MRS4062 was ineffective. Blockage of the P2Y11receptor or its coupling to adenylate cyclase boosted UTP-induced CF proliferation. Confocal microscopy and Western blot analysis confirmed the presence of P2Y2, P2Y4 and P2Y11 receptors. Data indicate that besides P2Y4 and P2Y2 receptors which are responsible for UTP-induced [Ca2+]i transients and growth of CF, respectively, synchronous activation of the previously unrecognized P2Y11 receptor may represent an important target for anti-fibrotic intervention in cardiac remodeling.

Stenosis of the Branches of the Neopulmonary Artery after the Arterial Switch Operation: a Cardiac Magnetic Resonance Imaging Study

Background : The neonatal arterial switch operation (ASO) is now the standard of care for children born with transposition of the great arteries. Stenosis of the neopulmonary artery on long‑term follow up is a known complication. Methods : We performed a retrospective analysis of eleven patients who underwent a cardiac magnetic resonance imaging (MRI) due to echocardiographic evidence suggestive of stenosis of the neopulmonary artery or its branches (mean estimated Doppler gradient 48 mmHg, min 30 mmHg, max 70 mmHg). A comprehensive evaluation of anatomy and perfusion was done by cardiac MRI. Results : The branches of the neopulmonary artery (neo PA) showed decreased caliber in three patients unilaterally and in two patients, bilaterally. Magnetic resonance (MR) perfusion studies showed concomitant decreased flow, with discrepancy between the two lungs of 35/65% or worse, only in the three patients with unilateral obstruction, by two different MR perfusion methods. Conclusions : Cardiac MR can be used as a comprehensive non‑invasive imaging technique to diagnose stenosis of the branches of the neopulmonary after the ASO, allowing evaluation of anatomy and function of the neoPA, its branches, and the differential perfusion to each lung, thus facilitating clinical decision making.

Understanding Cardiac Myxoma Recurrence: A Case Report

Recurrence of cardiac myxoma is a rare condition, observed in about 3% of patients in sporadic cases, although it is more frequent in familial ones. Several mechanisms have been proposed to explain such recurrence, and the importance of increased vascularization as a facilitating feature is the subject of debate. The authors report the case of a non-familial right atrial myxoma, unusual for both its histopathology and recurrence.

New mechanisms that regulate the expression of genes implicated in the process of ketogenesis

Dissertação para obtenção do Grau de Mestre em Biotecnologia

Strength and damage analysis of composite-aluminium adhesively-bonded single-lap joints

With the need to find an alternative way to mechanical and welding joints, and at the same time to overcome some limitations linked to these traditional techniques, adhesive bonds can be used. Adhesive bonding is a permanent joining process that uses an adhesive to bond the components of a structure. Composite materials reinforced with fibres are becoming increasingly popular in many applications as a result of a number of competitive advantages. In the manufacture of composite structures, although the fabrication techniques reduce to the minimum by means of advanced manufacturing techniques, the use of connections is still required due to the typical size limitations and design, technological and logistical aspects. Moreover, it is known that in many high performance structures, unions between composite materials with other light metals such as aluminium are required, for purposes of structural optimization. This work deals with the experimental and numerical study of single lap joints (SLJ), bonded with a brittle (Nagase Chemtex Denatite XNRH6823) and a ductile adhesive (Nagase Chemtex Denatite XNR6852). These are applied to hybrid joints between aluminium (AL6082-T651) and carbon fibre reinforced plastic (CFRP; Texipreg HS 160 RM) adherends in joints with different overlap lengths (LO) under a tensile loading. The Finite Element (FE) Method is used to perform detailed stress and damage analyses allowing to explain the joints’ behaviour and the use of cohesive zone models (CZM) enables predicting the joint strength and creating a simple and rapid design methodology. The use of numerical methods to simulate the behaviour of the joints can lead to savings of time and resources by optimizing the geometry and material parameters of the joints. The joints’ strength and failure modes were highly dependent on the adhesive, and this behaviour was successfully modelled numerically. Using a brittle adhesive resulted in a negligible maximum load (Pm) improvement with LO. The joints bonded with the ductile adhesive showed a nearly linear improvement of Pm with LO.

National Registry on Cardiac Electrophysiology (2012)

Based on a survey sent to Portuguese centers that perform diagnostic and interventional electrophysiology and/or implantable cardioverter-defibrillator (ICD) implantations, the authors analyze the number and type of procedures performed during 2012 and compare these data with previous years. In 2012, a total of 2561 diagnostic electrophysiologic studies were performed, which were followed by ablation in 2017 cases, representing a steady situation compared with the previous year. There was a 12% increase in the number of ablation procedures for atrial fibrillation, making it for the first time the most frequent indication for ablation, overtaking atrioventricular nodal reentrant tachycardia. The total number of first ICD implantations was 1048 (around 100 per million population), of which 375 were cardiac resynchronization devices (BiV ICDs). This represents a slight decrease (3.3%) in the total number of new implants, with an increase of 10% in the number of BiV ICDs compared to the previous year. However, there was a considerable increase in the number of ICD generator replacements, resulting in an overall increase of 3.5% in implantations performed in 2012. Some comments are made regarding developments in this activity and its current status, and on some factors that may influence the dynamics of this area of interventional cardiology.

Empirical models for quantification of machining damage in composite materials

Dissertação para obtenção do Grau de Doutor em Engenharia Mecânica