Seismic retrofit of masonry-to-timber connections in historical constructions

Tese de Doutoramento em Engenharia Civil.

MMP-9/RECK imbalance: a mechanism associated with high-grade cervical lesions and genital infection by Human Papillomavirus (HPV) and Chlamydia trachomatis

"Manuscript"

Estudo da cabeceira da Sé do Porto

Dissertação de mestrado integrado em Engenharia Civil

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.

Arterial distensibility as a possible compensatory mechanism in chronic aortic regurgitation

OBJECTIVE: To evaluate elastic properties of conduit arteries in asymptomatic patients who have severe chronic aortic regurgitation. METHODS: Twelve healthy volunteers aged 30±1 years (control group) and 14 asymptomatic patients with severe aortic regurgitation aged 29±2 years and left ventricular ejection fraction of 0.61±0.02 (radioisotope ventriculography) were studied. High-resolution ultrasonography was performed to measure the systolic and diastolic diameters of the common carotid artery. Simultaneous measurement of blood pressure enabled the calculation of arterial compliance and distensibility. RESULTS: No differences were observed between patients with aortic regurgitation and the control group concerning age, sex, body surface, and mean blood pressure. Pulse pressure was significantly higher in the aortic regurgitation group compared with that in the control group (78±3 versus 48±1mmHg, P<0.01). Arterial compliance and distensibility were significantly greater in the aortic regurgitation group compared with that in the control group (11.0±0.8 versus 8.1±0.7 10-10 N-1 m4, P=0.01 e and 39.3±2.6 versus 31.1±2.0 10-6 N-1 m², P=0.02, respectively). CONCLUSION: Patients with chronic aortic regurgitation have increased arterial distensibility. Greater vascular compliance, to lessen the impact of systolic volume ejected into conduit arteries, represents a compensatory mechanism in left ventricular and arterial system coupling.

Cardiac Damage from Chronic Use of Chloroquine: A Case Report and Review of the Literature

Chloroquine has been widely used in rheumatological treatment, but potential severe side effects require careful follow-up. Cardiac damage is not a common consequence, but its clinical relevance has not yet been described. We report the case of a 58-year-old woman with rheumatoid arthritis, in whom chronic chloroquine use resulted in major irreversible cardiac damage. She presented with syncopal episodes due to complete atrioventricular block confirmed by electrophysiological study whose changes were concluded to be irreversible and a permanent pacemaker was indicated. Endomyocardial biopsy was also performed to search for histopathological and ultrastructural cardiac damage. We also reviewed the 22 cases of chloroquine-induced cardiopathy described to date as well as its pathophysiology.

Endothelium-dependent relaxation in response to poly-L-arginine in canine coronary arteries: implications about hyperpolarization as a mechanism of vasodilatation

OBJECTIVE: To study the mechanism by which poly-L-arginine mediates endothelium-dependent relaxation. METHODS: Vascular segments with and without endothelium were suspended in organ chambers filled with control solution maintained at 37ºC and bubbled with 95% O2 / 5% CO2. Used drugs: indomethacin, acetycholine, EGTA, glybenclamide, ouabain, poly-L-arginine, methylene blue, N G-nitro-L-arginine, and verapamil and N G-monomethyl-L-arginine. Prostaglandin F2á and potassium chloride were used to contract the vascular rings. RESULTS: Poly-L-arginine (10-11 to 10-7 M) induced concentration-dependent relaxation in coronary artery segments with endothelium. The relaxation to poly-L-arginine was attenuated by ouabain, but was unaffected by glybenclamide. L-NOARG and oxyhemoglobin caused attenuation, but did not abolish this relaxation. Also, the relaxations was unaffected by methylene blue, verapamil, or the presence of a calcium-free bathing medium. The endothelium-dependent to poly-L-arginine relaxation was abolished only in vessels contracted with potassium chloride (40 mM) in the presence of L-NOARG and indomethacin. CONCLUSION: These experiments indicate that poly-L-arginine induces relaxation independent of nitric oxide.

Senescencia de celulas T humanas inducida por tumores: un nuevo mecanismo de evasión de la respuesta inmune. Senescence of human T cells iduced by tumors. A new mechanism of evasion of immune response.

La respuesta antitumoral en individuos con cáncer depende, en gran medida, de células del sistema inmune capaces de reconocer y eliminar las células tumorales. Sin embargo, los tumores tienen la capacidad de evadir la respuesta inmune a través de diversos mecanismos como por ejemplo inducir la muerte de células claves del sistema inmune [1-3]. Previamente nosotros demostramos mediante un modelo in vitro que dependiendo de las condiciones de interacción entre tumor y linfocitos (tiempo y relación numérica), los tumores pueden inducir apoptosis o senescencia de linfocitos T provenientes de donantes sanos. Nuestros resultados son los primeros en demostrar que células tumorales de diversos orígenes pueden inducir senescencia de células T a través de factor/s solubles. También demostramos que a diferencia con los que ocurre in vivo, tanto las células CD4 como las CD8 son susceptibles a adquirir fenotipo de senescencia. Estudiando las implicancias que puede tener la senescencia sobre la funcionalidad de la célula T, observamos que las células T CD4+ y CD8+ senescentes pueden suprimir una respuesta linfoproliferativa. Si bien las células CD8+CD28- han sido identificadas in vivo, nosotros demostramos que células CD4+ CD28- tiene capacidad supresora [4]. En base a estos resultados, nuestra hipótesis es que las células T senescentes inducida por tumores pueden regular nuestro sistema de defensa actuando sobre la respuesta inmune adaptativa y posiblemente sobre la innata y, por consiguiente, postulamos que la senescencia de células T puede ser considerada como otro de los mecanismos de evasión de la respuesta inmunePlanteamos así los siguientes objetivos específicos: -Evaluar como las células T senescentes inducidas por tumores pueden regular la respuesta inmune.-Evaluar la participación de mediadores solubles capaces de regular la senescencia de células T inducida por tumores. En la actualidad existen estrategias inmuno-terapéuticas que avizoran resultados promisorios. Sin embargo, el control de células T inmunosupresoras permanece como unos de los grandes desafíos. Nuestro proyecto proveerá conocimientos sobre un fenómeno muy poco estudiado y por consiguiente muy poco valorado a la hora de diseñar estrategias terapéuticas para la cura del cáncer.

Control of spiral wave dynamics by feedback mechanism via a triangular sensory domain

Spiral wave,feedback mechanism, photosensitive BZ reaction, excitable media, drift vetor field plot, planewave approximation, BZ, nonlinear

Reverse Cardiac Remodeling: A Marker of Better Prognosis in Heart Failure

In heart failure syndrome, myocardial dysfunction causes an increase in neurohormonal activity, which is an adaptive and compensatory mechanism in response to the reduction in cardiac output. Neurohormonal activity is initially stimulated in an attempt to maintain compensation; however, when it remains increased, it contributes to the intensification of clinical manifestations and myocardial damage. Cardiac remodeling comprises changes in ventricular volume as well as the thickness and shape of the myocardial wall. With optimized treatment, such remodeling can be reversed, causing gradual improvement in cardiac function and consequently improved prognosis.

Modelling the influence of microstructure on elastic properties and tensile damage behaviour of Mo-base silicide alloys

Mo-Si-B alloys, Real microstructures, Voronoi structures, Microstructural characterization, Modelling and finite element simulations, Effective material properties, Damage and Crack growth, tensile strength, fracture toughness

Micro scale modeling grain boundary damage under creep conditions

Magdeburg, Univ., Fak. für Maschinenbau, Diss., 2014

Identification technique of mechanism-based constitutive model for cast iron under thermo-mechanical loads

Magdeburg, Univ., Fak. für Maschinenbau, Diss., 2015