Advanced image processing techniques for detection and quantification of drusen

Dissertation presented to obtain the degree of Doctor of Philosophy in Electrical Engineering, speciality on Perceptional Systems, by the Universidade Nova de Lisboa, Faculty of Sciences and Technology

Tectónica da cadeia da Arrábida

Geociências, Museu Nac. Hist. Nat. Univ. Lisboa, nº 2, 35-84

Communication and choice in yeast mating

Dissertação apresentada para obtenção do grau de doutor em Biologia de Sistemas pelo Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa.

Evaluation of the schistosomicidal efficacy of liposome - Entrapped Oxamniquine

Oxamniquine (OXA) was sucessfully encapsulated in small unilamellar vesicles using a pH gradient method. This procedure led to a high drug encapsulation efficiency (> 85%) at a drug to lipid molar ratio of 1/10. Moreover, these liposomes were found to retain encapsulated OXA efficciently under dialysis conditions at 37º C. Liposome-entrapped OXA (LOXA), OXA, and empty liposomes were tested against Schistosoma mansoni in a murine model. LOXA produced a significant reduction of the worm burden compared to the other preparations, when inoculated by subcutaneous route (s.c.) with 10 mg OXA/kg animal one day before the infection, and 3, 7, and 14 days after. However, LOXA was not effective when given 7 days before, or 35 days after infections. OXA, in the free form, was effective in relation to the untreated group, only when administered 3 days after the infection. Maximum effect of LOXA, with 97% reduction of the parasite number, was observed when the preparation was given s.c.one day before the infection. On the other hand, LOXA inoculated intraperitoneally one day before the infection didn’t show any reduction of the parasite count. It can be concluded that LOXA is more effective than OXA for the treatment of experimental schistosomiasis, particularly when administered subcutaneously at a time close to the infection

Trypanosoma cruzi: chemotherapy with benznidazole in mice inoculated with strains from Paraná State and from different endemic areas of Brazil

Strains of Trypanosoma cruzi from different geographical areas have shown different levels of susceptibility to trypanocidal drugs. The susceptibility in vivo to benznidazole was investigated in eighteen strains of T. cruzi. Twelve were isolated from chronic chagasic patients from different Chagas’ disease endemic areas. The other six strains were isolated from the northwestern region of Paraná state; two of them from patients three from triatomines (Triatoma sordida) and one from wild reservoir (Didelphis sp.). To test drug the infected mice were divided into two groups of twenty. One group was treated with benznidazole for twenty consecutive days and the other group was used as untreated control. The treatment began after detection of the infection by direct blood examination or haemoculture. The control of cure was done through haemoculture and indirect immunofluorescence test. The drug eliminated the inflammatory lesions of the skeletal muscle of mice considered cured and from the heart of most of them. Moreover, the inflammatory lesions were reduced in treated but not cured animals. The T. cruzi strains studied showed a gradient of drug susceptibility that varied from 0% to 100%. Ten strains were considered sensitive to the treatment (61 to 100% of cure), one strain was partially sensitive (50% of cure) and seven strains were considered resistant to the treatment (0 to 40% of cure). This variation was observed both in strains of T. cruzi isolated from domestic and sylvatic cycles

Correction of spatial distortion in magnetic resonance imaging

Dissertation to Obtain the Degree of Master in Biomedical Engineering

Detection of HIV and HCV RNA in semen from Brazilian coinfected men using multiplex PCR before and after semen washing

INTRODUCTION: Prolonged survival of patients under HAART has resulted in new demands for assisted reproductive technologies. HIV serodiscordant couples wish to make use of assisted reproduction techniques in order to avoid viral transmission to the partner or to the newborn. It is therefore essential to test the effectiveness of techniques aimed at reducing HIV and HCV loads in infected semen using molecular biology tests. METHODS: After seminal analysis, semen samples from 20 coinfected patients were submitted to cell fractioning and isolation of motile spermatozoa by density gradient centrifugation and swim-up. HIV and HCV RNA detection tests were performed with RNA obtained from sperm, seminal plasma and total semen. RESULTS: In pre-washing semen, HIV RNA was detected in 100% of total semen samples, whereas HCV RNA was concomitantly amplified in only one specimen. Neither HIV nor HCV were detected either in the swim-up or in the post-washing semen fractions. CONCLUSIONS: Reduction of HIV and/or HCV shedding in semen by density gradient centrifugation followed by swim-up is an efficient method. These findings lead us to believe that, although semen is rarely found to contain HCV, semen processing is highly beneficial for HIV/HCV coinfected individuals.

Intraocular Pressure Correlates with Optic Nerve Sheath Diameter in Patients with Normal Tension Glaucoma

PURPOSE: 1. Identify differences in optic nerve sheath diameter (ONSD) as an indirect measure of intracranial pressure (ICP) in glaucoma patients and a healthy population. 2. Identify variables that may correlate with ONSD in primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG) patients. METHODS: Patients with NTG (n = 46) and POAG (n = 61), and healthy controls (n = 42) underwent B-scan ultrasound measurement of ONSD by an observer masked to the patient diagnosis. Intraocular pressure (IOP) was measured in all groups, with additional central corneal thickness (CCT) and visual field defect measurements in glaucomatous patients. Only one eye per patient was selected. Kruskal-Wallis or Mann-Whitney were used to compare the different variables between the diagnostic groups. Spearman correlations were used to explore relationships among these variables. RESULTS: ONSD was not significantly different between healthy, NTG and POAG patients (6.09 ± 0.78, 6.03 ± 0.69, and 5.71 ± 0.83 respectively; p = 0.08). Visual field damage and CCT were not correlated with ONSD in either of the glaucoma groups (POAG, p = 0.31 and 0.44; NTG, p = 0.48 and 0.90 respectively). However, ONSD did correlate with IOP in NTG patients (r = 0.53, p < 0.001), while it did not in POAG patients and healthy controls (p = 0.86, p = 0.46 respectively). Patient's age did not relate to ONSD in any of the groups (p > 0.25 in all groups). CONCLUSIONS: Indirect measurements of ICP by ultrasound assessment of the ONSD may provide further insights into the retrolaminar pressure component in glaucoma. The correlation of ONSD with IOP solely in NTG patients suggests that the translaminar pressure gradient may be of particular importance in this type of glaucoma.

A comparison between thin film solar cells made from co-evaporated CuIn1-xGaxSe2using a one-stage process versus a three-stage process

Until this day, the most efficient Cu(In,Ga)Se2 thin film solar cells have been prepared using a rather complex growth process often referred to as three-stage or multistage. This family of processes is mainly characterized by a first step deposited with only In, Ga and Se flux to form a first layer. Cu is added in a second step until the film becomes slightly Cu-rich, where-after the film is converted to its final Cu-poor composition by a third stage, again with no or very little addition of Cu. In this paper, a comparison between solar cells prepared with the three-stage process and a one-stage/in-line process with the same composition, thickness, and solar cell stack is made. The one-stage process is easier to be used in an industrial scale and do not have Cu-rich transitions. The samples were analyzed using glow discharge optical emission spectroscopy, scanning electron microscopy, X-ray diffraction, current–voltage-temperature, capacitance-voltage, external quantum efficiency, transmission/reflection, and photoluminescence. It was concluded that in spite of differences in the texturing, morphology and Ga gradient, the electrical performance of the two types of samples is quite similar as demonstrated by the similar J–V behavior, quantum spectral response, and the estimated recombination losses.

Exercise-Induced Intraventricular Obstruction in a Child with Near Syncope and Chest Pain During Exercise

We report the case of a 10-year-old girl with two episodes of light-headedness and chest pain during exercise. She had an unremarkable clinical record, physical examination, ECG, and echocardiogram. Noninvasive ischemia tests were positive, but coronary angiography was normal. Exercise stress echocardiogram revealed an exercise-induced intra-left-ventricular obstruction with a peak gradient of 78 mmHg and replicated her symptoms. After starting beta-blocker therapy her clinical status improved and no residual obstruction was detected. The authors review this unsuspected clinical condition, seldom reported in the adult population and, to our knowledge, never before in a child.

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.

Correlation between the mechanical cycling behavior and microstructure in laser welded joints using NiTi memory shape alloys

Dissertação para obtenção do Grau de Mestre em Engenharia de Materiais

Automated segmentation, tracking and evaluation of bacteria in microscopy images

Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica

Estudo sobre viabilidade de produção descentralizada de energia à custa do efeito chaminé

A procura por alternativas ao atual paradigma energético, que se caracteriza por uma predominância indiscutível das fontes combustíveis fósseis, é o motivo primário desta investigação. A energia emitida pelo Sol que chega à Terra diariamente ultrapassa em várias ordens de grandeza a energia que a nossa sociedade atual necessita. O efeito chaminé é uma das formas de aproveitar essa energia. Este efeito tem origem no diferencial de temperaturas existente entre o interior e o exterior de uma chaminé, que provoca um gradiente nas massas volúmicas do fluido entre o interior e o exterior da chaminé, induzindo assim um fluxo de ar. Esta diferença de temperaturas radica na exposição da face exterior da chaminé à radiação solar. No sistema que nos propomos estudar, o ar entra na chaminé por pequenos orifícios situados na sua base, e, ao tomar contacto com as paredes internas da chaminé, aquece desde a temperatura ambiente, Ta, até à temperatura interna, Ti . Este aumento de temperatura torna o ar dentro da chaminé mais “leve” em comparação com o ar mais frio do exterior levando-o a ascender ao longo do interior da chaminé. Este escoamento contém energia cinética que pode, por exemplo, ser transformada em energia elétrica por intermédio de turbinas. A eficiência de conversão da energia será tanto maior quanto menor for a velocidade do ar a jusante da turbina. Esta tecnologia poderá ser instalada de forma descentralizada, como acontece com as atuais centrais concentradoras solares térmicas e fotovoltaicas localizadas na periferia de grandes cidades ou, alternativamente, poderá ser inserida no próprio tecido urbanístico. A investigação demonstra que as dimensões da chaminé, a irradiação e a temperatura do ar são os fatores com maior impacto na potência hidráulica gerada.

Characterization of sol-gel matrices with entrapped cutinase

Dissertação para obtenção do Grau de Doutor em Engenharia Química e Bioquímica