Development of computational and experimental methods for biomass composition and evaluation of its impact in genome-scale models prediction

The use of genome-scale metabolic models has been rapidly increasing in fields such as metabolic engineering. An important part of a metabolic model is the biomass equation since this reaction will ultimately determine the predictive capacity of the model in terms of essentiality and flux distributions. Thus, in order to obtain a reliable metabolic model the biomass precursors and their coefficients must be as precise as possible. Ideally, determination of the biomass composition would be performed experimentally, but when no experimental data are available this is established by approximation to closely related organisms. Computational methods however, can extract some information from the genome such as amino acid and nucleotide compositions. The main objectives of this study were to compare the biomass composition of several organisms and to evaluate how biomass precursor coefficients affected the predictability of several genome-scale metabolic models by comparing predictions with experimental data in literature. For that, the biomass macromolecular composition was experimentally determined and the amino acid composition was both experimentally and computationally estimated for several organisms. Sensitivity analysis studies were also performed with the Escherichia coli iAF1260 metabolic model concerning specific growth rates and flux distributions. The results obtained suggest that the macromolecular composition is conserved among related organisms. Contrasting, experimental data for amino acid composition seem to have no similarities for related organisms. It was also observed that the impact of macromolecular composition on specific growth rates and flux distributions is larger than the impact of amino acid composition, even when data from closely related organisms are used.

Avaliação experimental da utilização de conectores indentados em elementos mistos de aço e betão leve

Dissertação de mestrado integrado em Engenharia Civil

Estudo numérico do escoamento e transporte de sedimentos em torno de pilares de pontes

Dissertação de mestrado integrado em Engenharia Civil

A perda precoce do diâmetro luminal após angioplastia coronária e sua influência no fenômeno da reestenose

OBJETIVO: Analisar a perda do diâmetro luminal mínimo (DLM) nos primeiros 15min após angioplastia coronária por balão (AC), quantificando sua influência na reestenose coronária. MÉTODOS: Foram estudadas, prospectivamente, 86 AC em 86 pacientes. Os pacientes foram divididos em dois subgrupos de acordo com a presença ou ausência de reestenose; o 1º grupo compreendendo as 31 lesões com reestenose e o 2º, as 55 lesões sem reestenose. RESULTADOS: A análise univariada mostrou que a relação balão/artéria foi menor no grupo com reestenose (0,92±0,01 vs 1,00±0,11, P= .003). O grupo com reestenose apresentou maior recolhimento elástico absoluto e relativo no 1°min (0,79±0,54 vs 0,68±0,59mm; P= 0,007 e 32,04±14,27 vs 22,15±16,65%; P= 0,006.) e no controle angiográfico do 15°min (1,25±0,59 vs 0,90±0,65mm, P= 0,017 e 46,75±15,69 vs 29,18±17,84%, P<0,00001) do que o grupo sem reestenose. O DLM no 1°min foi menor no grupo com reestenose (2,15±0,42 vs 2,43±0,58mm; P=0,022). O grupo com reestenose apresentou uma maior perda precoce no DLM (0,46±0,34 vs 0,22±0,35mm, P= 0,004). Este decréscimo na luz do vaso determinou que o DLM do 15°min fosse ainda menor no grupo com reestenose (1,69±0,48 vs 2,20±0,61; P= 0,0001). Da análise multivariada, entretanto, identificou-se apenas a relação balão/artéria e o DLM do 15°min como os dois fatores independentes mais relacionados à reestenose. CONCLUSÃO: O recolhimento elástico e a perda do DLM ao longo dos 15min são fatores diretamente relacionados à reestenose. Entretanto, a análise multivariada mostrou que a relação balão/artéria e o DLM de 15min são os dois fatores independentes mais fortemente preditores de reestenose.

Fluência no betão desde as primeiras idades: um estudo experimental

Dissertação de mestrado integrado em Engenharia Civil

Cyberbullying: caracterização do fenómeno em Portugal

Dissertação de mestrado em Crime, Diferença e Desigualdade

Efeito da berinjela sobre os lípides plasmáticos, a peroxidação lipídica e a reversão da disfunção endotelial na hipercolesterolemia experimental

OBJETIVO: Estudar o efeito do suco da berinjela sobre os lípides plasmáticos, o colesterol tecidual, a peroxidação lipídica das LDL nativas, oxidadas e da parede arterial e o relaxamento dependente do endotélio, em coelhos hipercolesterolêmicos. MÉTODOS: Coelhos foram separados em grupos controle (GC), hipercolesterolêmico (GH) e berinjela (GB), (n=10). Os animais do GC foram alimentados com ração normal, o GH e o GB com ração acrescentada de colesterol (0,5%) e gordura de babaçu (10%) durante 30 dias. Ao GB acrescentou-se suco de berinjela, nos últimos 15 dias do experimento. Os lípides plasmáticos foram medidos através de kits enzimáticos, a peroxidação lipídica pela dosagem do malondialdeído (MDA) e o relaxamento dependente do endotélio, por curvas de concentração efeito pela acetilcolina e nitroprussiato. RESULTADOS: O peso dos animais foi menor no GB em relação ao GC e GH (p<0,05). O colesterol total plasmático, as LDL e os triglicérides que se elevaram no GH, reduziram-se em 19%, 29% e 38%, respectivamente no GB (p<0,05). O colesterol tecidual foi menor no GB (50%) em relação ao GH (p<0,05). Nos animais do GB ocorreu redução significante do teor de MDA nas LDL nativas (56%) e oxidadas (22%), assim como na parede arterial (30%) (p<0,05). O relaxamento máximo dependente do endotélio, , elevou-se significantemente em 28% no GB em relação ao GH (p<0,05). CONCLUSÃO: O suco de berinjela administrado a coelhos hipercolesterolêmicos reduziu significantemente o peso corpóreo, o colesterol total, as LDL plasmáticas, os triglicérides, o colesterol tecidual, a peroxidação lipídica das LDL nativas, oxidadas e da parede arterial, assim como aumentou o relaxamento dependente do endotélio.

O Google [2000-2004]: a emergência de um fenómeno global

"Colecção: Comunicação e sociedade - 12"

O novo luxo: um novo olhar sobre o fenómeno

Dissertação de mestrado em Design e Marketing da Moda

Effects of lisinopril on experimental ischemia in rats. Influence of infarct size

OBJECTIVE - Angiotensin-converting enzyme inhibitors (ACEIs) have gained importance in preventing or attenuating the process of ventricular remodeling after myocardial infarction. The significance of infarct size in regard to the response to ACEIs, however, is controversial. This study aimed to analyze the effects of lisinopril on mortality rate, cardiac function, degree of cardiac hypertrophy and fibrosis in rats with different infarct sizes. METHODS - Lisinopril (20 mg/kg/day) dissolved in drinking water was administered to rats immediately after coronary artery occlusion. After being sacrificed, the infarcted animals were divided into two groups: one group of animals with small infarcts (< 40% of the left ventricle) and another group of animals with large infarcts (> 40% of the left ventricle). RESULTS - The mortality rate was 31.7% in treated rats and 47% in the untreated rats. There was no statistical difference between the groups with small and large infarcts in regard to myocardial concentration of hydroxyproline. In small infarcts, the treatment attenuated the heart dysfunction characterized by lower levels of blood pressure and lower values of the first derivative of pressure and of the negative derivative of pressure. The degree of hypertrophy was also attenuated in small infarcts. In regard to large infarcts, no differences between the groups were observed. CONCLUSION - Treatment with the ACEIs had no effect on mortality rate and on the amount of fibrosis. The protective effect of lisinopril on heart function and on the degree of hypertrophy could only be detected in small infarcts

Experimental analysis of Maritime pine and Iroko single shear dowel-type connections

"Available online 21 March 2016"

Effects of losartan on ventricular remodeling in experimental infarction in rats

OBJECTIVE: To evaluate the effects of losartan on ventricular remodeling and on survival after myocardial infarction in rats. METHODS: After surgical occlusion of left coronary artery, 84 surviving male Wistar rats were divided into two groups: LO treated with losartan (20mg/kg/day, n=33) and NT (n=51), without medication. After 3 months, we analyzed mortality; ventricular to body mass ratio (VM /BM); myocardial hydroxyproline concentration (HOP); isovolumetric pressure, +dp/dt, -dp/dt, and diastolic volume/left ventricle mass ratio (VO/LV). RESULTS: Mortality was: LO = 22%, and NT = 47% (p<0.05). Ventricular mass,(VM/BM, mg/g) was 4.14 ± 0.76 and 3.54±0.48, in the NT and LO groups, respectively (p<0.05). HOP (median) was 4.92 upsilong/mg in the LO and 5.54 upsilong/g in the NT group (p>0.05). The V0/LV values (median) were 0.24 mL/g in group LO and 0.31 mL/g in group NT (p<0.05) compared to NT group. There were no differences between the groups for +dp/dt and -dp/dt parameters. CONCLUSION: 1- The use of losartan myocardial infarction causes an attenuation of ventricular remodeling, bringing about an increased survival, an attenuation of ventricular hypertrophy and dilation, and an improvement of the isovolumetric pressure; 2- the treatment does not modify the myocardial collagen concentration.

Effect of Propafenone on the Contractile Activity of Latissimus Dorsi Muscle Isolated in an Organ Chamber: Experimental Study in Rats

OBJECTIVE: To study the effect of propafenone on the contractile function of latissimus dorsi muscle isolated from rats in an organ chamber. METHODS: We studied 20 latissimus dorsi muscles of Wistar rats and divided them into 2 groups: group I (n=10), or control group - we studied the feasibility of muscle contractility; group II (n=10), in which the contralateral muscles were grouped - we analyzed the effect of propafenone on muscle contractility. After building a muscle ring, 8 periods of sequential 2-minute baths were performed, with intervals of preprogrammed electrical stimulation using a pacemaker of 50 stimuli/min. In group II, propafenone, at the concentration of 9.8 µg/mL, was added to the bath in period 2 and withdrawn in period 4. RESULTS: In group I, no significant depression in muscle contraction occurred up to period 5 (p>0.05). In group II, a significant depression occurred in all periods, except between the last 2 periods (p<0.05). Comparing groups I and II only in period 1, which was a standard period for both groups, we found no significant difference (p>0.05). CONCLUSION: Propafenone had a depressing effect on the contractile function of latissimus dorsi muscle isolated from rats and studied in an organ chamber.

Development of a water-in-oil-in-water multiple emulsion system integrating biomimetic aqueous-core lipid nanodroplets for protein entity stabilization. Part I: experimental factorial design

Lipid nanoballoons integrating multiple emulsions of the type water-in-oil-in-water enclose, at least in theory, a biomimetic aqueous-core suitable for housing hydrophilic biomolecules such as proteins, peptides and bacteriophage particles. The research effort entertained in this paper reports a full statistical 23x31 factorial design study (three variables at two levels and one variable at three levels) to optimize biomimetic aqueous-core lipid nanoballoons for housing hydrophilic protein entities. The concentrations of protein, lipophilic and hydrophilic emulsifiers, and homogenization speed were set as the four independent variables, whereas the mean particle hydrodynamic size (HS), zeta potential (ZP) and polydispersity index (PI) were set as the dependent variables. The V23x31 factorial design constructed led to optimization of the higher (+1) and lower (-1) levels, with triplicate testing for the central (0) level, thus producing thirty three experiments and leading to selection of the optimized processing parameters as 0.015% (w/w) protein entity, 0.75% (w/w) lipophilic emulsifier (soybean lecithin) and 0.50% (w/w) hydrophilic emulsifier (poloxamer 188). In the present research effort, statistical optimization and production of protein derivatives encompassing full stabilization of their three-dimensional structure, has been attempted via housing said molecular entities within biomimetic aqueous-core lipid nanoballoons integrating a multiple (W/O/W) emulsion.

Experimental validation of a proposed single-phase five-level active rectifier operating with model predictive current control

This paper presents a model predictive current control applied to a proposed single-phase five-level active rectifier (FLAR). This current control strategy uses the discrete-time nature of the active rectifier to define its state in each sampling interval. Although the switching frequency is not constant, this current control strategy allows to follow the reference with low total harmonic distortion (THDF). The implementation of the active rectifier that was used to obtain the experimental results is described in detail along the paper, presenting the circuit topology, the principle of operation, the power theory, and the current control strategy. The experimental results confirm the robustness and good performance (with low current THDF and controlled output voltage) of the proposed single-phase FLAR operating with model predictive current control.