The involvement of CDH1 in cancer angiogenesis

Dissertação para obtenção do Grau de Mestre em BiotecnologiaCancer is one of the leading causes of death worldwide. Biological hallmarks such as induced and sustained angiogenesis are implicated in tumour progression, as well as invasion and metastasis which are the major causes of cancer-related mortality. E-Cadherin impairment on the cell membrane is intimately related with invasion and metastasis. Also, increased levels of vascular endothelial growth factor (VEGF), an angiogenic marker, and its receptor on the plasma membrane can be implicated in tumour progression. This work was focused on how the inactivation of E-Cadherin, a molecule associated to an invasive phenotype can be related with angiogenesis, probably through VEGF-A expression. Two different cell lines without expression of E-Cadherin and stably transduced to express wild-type (WT) E-Cadherin were used to carry out this study: AGS Par/WT (from stomach) and MDA-435 Mock/WT (from breast). Immunohistochemical staining was performed to determine the cellular localization and western blot analysis was performed to assess the expression levels of E-Cadherin. VEGFA mRNA levels were assessed by quantitative Real-time PCR. Additionally, we determined the levels phosphorylated (phospho) ERK1/2, as well as the expression levels of total ERK1/2. To study the angiogenic role of E-cadherin the chick embryo Chorioallantoic Membrane (CAM) assay was used. We characterise in vivo the different cell lines concerning both angiogenic and tumorigenic responses dependent on E-Cadherin. Only cell lines stably expressing WT human E-Cadherin showed levels of expression of this protein at the cell membrane regardless of their tissue of origin. In vitro, AGS and MDA-435 cells expressing WT E-Cadherin revealed an increased expression of VEGFA in comparison to the control although not statically significant. In addition, both phospho-ERK1/2 and total ERK1/2 presented similar levels of expression regardless of the tissue of origin and E-Cadherin expression. Both angiogenic and tumorigenic responses in AGS WT was significantly increased in comparison to the control. The MDA-435 WT cells revealed increased tumorigenic response in comparison to the control. Overall, these results suggest that E-Cadherin expression is important for micro-tumour formation as well as for neovascularisation but this effect is dependent on the in vivo context

Minimum Loss Conditions in a Salient-Pole Wound-Field Synchronous Machine Drive

The conditions for minimum losses in a salient-pole wound-field synchronous machine (WFSM) drive are studied in this paper. The drive comprises a WFSM energized by a stator inverter and excited by a dc-dc converter both tied to a DC link. The minimum-loss operation is formulated as a nonlinear constrained optimization problem with equality constraints (e.g, torque command), and inequality constraints (flux, voltage and current limits). Lagrange multipliers are applied to solve this problem analytically. At low load, the torque demand can be met using different values for two independent electric variables (e.g. stator flux and field current magnitude). These can be optimized, thereby leading to two optimal implicit conditions. At higher load, when the stator flux reaches the maximum value, the free variables reduce to one and yield a single implicit optimal condition. For these two scenarios, the paper presents analytical derivations of the optimal conditions and numerical validation using MatLab. These conditions can be used to devise a control system optimizing the drive operation

Potencial energético dos efluentes da preparação da cortiça

Dada a elevada importância económica, social e ambiental da produção de cortiça em Portugal e tendo em conta a carga orgânica dos efluentes gerados por esta indústria, o presente trabalho apresenta um levantamento dos efluentes produzidos no sector da preparação da cozedura da cortiça e estima o potencial energético envolvido através da respectiva valorização energética por aplicação do processo de digestão anaeróbia. O valor global da energia que é possível obter do biogás produzido a partir dos efluentes da preparação da cortiça, numa base anual, ascende a 153 700-177 100 kWh (valor médio de 165 400 kWh). Sendo o biogás/metano uma fonte de energia e sendo o sector da preparação da cortiça um relevante consumidor de energia, o fluxo gasoso portador de energia, resultante do processo de tratamento por digestão anaeróbia, encontra aplicação directa no próprio processo da preparação da cortiça, podendo traduzir-se no aquecimento de 1755 m3 ano-1 de água para a cozedura da cortiça à temperatura de ebulição

Cork wastes treatment and biogas production

Cork industry is an important economic and social sector in the western Mediterranean region. Portugal is the producer and processing leader of this sector. The cork processing industry gives rise to several effluents that must be treated and valorised. This work is a part of a study that aims to develop an integrated process in order to maximize the valorization of the different wastes/effluents of the cork processing sector taking in count the biorefinery concept. The main objective of the present work is to conduct a survey of all operations involve in the cork processing and identify the possible effluents which may be treated and valorise by anaerobic digestion for energy production

Production and characterization of electrospun composite fibers: confinement of thermosensitive microgels

Materials engineering focuses on the assembly of materials´ properties to design new products with the best performance. By using sub-micrometer size materials in the production of composites, it is possible to obtain objects with properties that none of their compounds show individually. Once three-dimensional materials can be easily customized to obtain desired properties, much interest has been paid to nanostructured poly-mers in order to build biocompatible devices. Over the past years, the thermosensitive microgels have become more common in the framework of bio-materials with potential applicability in therapy and/or diagnostics. In addition, high aspect ratio biopolymers fibers have been produced using the cost-effective method called electrospinning. Taking advantage of both microgels and electrospun fibers, surfaces with enhanced functionalities can be obtained and, therefore employed in a wide range of applications. This dissertation reports on the confinement of stimuli-responsive microgels through the colloidal electro-spinning process. The process mainly depends on the composition, properties and patterning of the precur-sor materials within the polymer jet. Microgels as well as the electrospun non-woven mats were investigated to correlate the starting materials with the final morphology of the composite fibers. PNIPAAm and PNIPAAm/Chitosan thermosensitive microgels with different compositions were obtained via surfactant free emulsion polymerization (SFEP) and characterized in terms of chemical structure, morphology, thermal sta-bility, swelling properties and thermosensitivity. Finally, the colloidal electrospinning method was carried out from spinning solutions composed of the stable microgel dispersions (up to a concentration of about 35 wt. % microgels) and a polymer solution of PEO/water/ethanol mixture acting as fiber template solution. The confinement of microgels was confirmed by Scanning Electron Microscopy (SEM). The electrospinning process was statistically analysed providing the optimum set of parameters aimed to minimize the fiber diameter, which give rise to electrospun nanofibers of PNIPAAm microgels/PEO with a mean fiber diameter of 63 ± 25 nm

An overview of the role of cytochrome P450 enzyme system in food-drug interactions and possible applications in veterinary medicine

Dissertação de Mestrado Integrado em Medicina VeterináriaCytochrome P450 enzymes (CYP) are hemoproteins belonging to the group of monooxygenases and one of the main enzymatic systems responsible for drug metabolism. In the present study, in vitro approach was applied to evaluate the relation of CYP-catalyzed activities between human, rabbit, minipig and mouse, using single substrate assays (MultiCYP 7-ethoxycoumarin 0-deethylase (ECOD), CYP1A1/2 7-ethoxyresorufin 0- deethylase (EROD), CYP2A6 coumarin 7-hydroxylase (COH), CYP3A4 midazolam 1- hydroxylase (OH-MDZ), and CYP2E1 chlorzoxazone 6-hydroxylase (OH-CLZ)). It was also studied plant extracts (Pinus sylvestris, Angelica archangelica, Mentha sp., Citrus grandis) and phytochemicals (8-Hydroxybergapten, 5,6-dihydroxyangelicin, α, β-Thujone, α-Thujone, angelicin, bergamottin, bergapten, bergaptol, cnidilin, imperatorin, isobergapten, isopimpinellin, lanatin, phellopterin, psoralen, sphondin, xanthotoxin) as potential inhibitors in CYP-related activities of hepatic human microsomes (CYP1A1/2 (EROD), CYP2A6 (COH), CYP3A4 (OH-MDZ)). This study showed that the lowest ECOD activity was detected in humans and there was no similarity between other species. CYP1A1/2 showed equivalent activities. The highest CYP activities in humans were found for CYP2A6 and CYP3A4. In CYP2E1 activity, two similar groups were recognized: human and mouse versus rabbit and minipig. EROD reaction was the most inhibited CYP-mediated reaction. COH reaction was inhibited by few compounds. The highest inhibition was detected among angular furocoumarins. Linear furocoumarins group had the lower inhibitory concentration of CYP3A4. Thujone showed weak inhibition of CYP activities.RESUMO - As enzimas do sistema citocromo P450 (CYP) são hemoproteinas pertencentes ao grupo das monoxigenases e um dos principais sistemas enzimáticos responsáveis pela metabolização de fármacos. Neste estudo foi avaliada a relação da actividade catalítica de diferentes CYPs entre humanos, coelhos, minipig e murganhos, recorrendo a substratos como sondas individuais in vitro para mensurar reacções especificas (MultiCYP 7-etoxicumarina 0-deetilase (ECOD), CYP1A1/2 7-etoxiresorufina 0-deetilase (EROD), CYP2A6 cumarina 7-hidroxilase (COH), CYP3A4 midazolam 1-hidroxilase (OH-MDZ), e CYP2E1 clorozoxazona 6-hidroxilase (OH-CLZ)). Também foram estudados extractos de plantas (Pinus sylvestris, Angelica archangelica, Mentha sp., Citrus grandis) e fitoquímicos (8-hidroxibergaptem, 5,6-dihidroxiangelicina, α, β-tujona, α-tujona, angelicina, bergamottin, bergapteno, bergaptol, cnidilina, imperatorina, isobergapteno, isopimpinelina, lanatin, felopterina, psoraleno, sphondin, xantotoxina) como potenciais inibidores da actividade catalítica dos CYPs microssomais hepáticos humanos (CYP1A1/2 (EROD), CYP2A6 (COH), CYP3A4 (OH-MDZ)). Neste estudo não foram detectadas actividades similires entre espécies na reacção ECOD e a actividade mais baixa foi detectada nos humanos. A reacção EROD dos CYP1A1/2 demonstrou actividades similares entre as diferentes espécies. As maiores actividades cataliticas verificadas nos humanos correspondem aos CYP2A6 e CYP3A4. No estudo da reacção do CYP2E1 foram determinados dois grupos distintos com actividades cataliticas similares: 1) humanos e murganhos, 2) coelhos e minipigs. No estudo de potenciais inibidores dos CYPs, a reacção EROD foi a mais inibida. Pelo contrário, a reacção COH foi inibida por poucos compostos. A maioria das inibições ocorreu por exposição a furocumarinas angulares. O grupo de furocumarinas lineares teve a menor concentração inibitória da reacção OH-MDZ do CYP3A4. Os fitoquímicos α, β-tujona e α- tujona demonstraram ter um fraco poder inibitório na actividade dos CYPs analisados

Lead bioremoval by cork residues as biosorbent

The intensification of industrial activity during the last few years has greatly contributed to the increase of heavy metals in the environment, mainly in the aquatic systems [1]. Conventional technologies traditionally used for the removal of heavy metals from aqueous solutions are expensive and inefficient at low metal concentrations [2]. Biosorption, which is a property of different types of biomass (biosorbents) to bind and concentrate heavy metals from even very dilute aqueous solutions, is one of the most promising technologies that can be used for this purpose [3]. The goal of this work was to study the bioremoval process of Pb(II) ions from aqueous dilute solutions by cork granulates (1-2 mm) from a Portuguese cork processing company. The effect of physico-chemical parameters such as initial metal solution, pH, biomass cork pre-treatments and initial metal and biosorbent concentrations on the metal removal efficiency were investigated. The maximum Pb(II) uptake capacity (Qmax) of cork biomass was also determined from the Langmuir isotherm. The results obtained showed that the optimum initial pH for Pb(II) removal was in the range 3-4, leading to removal yields of about 90-100% for initial metal concentrations of 10-100 mg/L. Cork biomass without treatment provided a higher removal yield (93%) than the biomass submitted to previous extraction with deionised water (80%), ethyl acetate (83%) and ethanol (88 %). The Langmuir model showed a very good correlation with experimental results (r2=0.995) and the Qmax was determined as being 5.3 mg Pb(II)/g cork. The optimisation of continuous bioremoval of Pb(II) (10 mg/L) from 25 L of influent, regarding metal uptake yield and volume of effluent containing a Pb(II) concentration 1 mg/L (MAV), was carried out by the factorial design methodology, leading to the establishment of the best operating conditions. In these conditions, two fixed bed-reactors (operational liquid volume of each reactor containing 20g of biosorbent=138 mL) running in sequential mode (feed flow rate - 590 mL/h) were more efficient (effluent volume with [Pb(II)] 1 mg/L=10 L) than one reactor alone (effluent volume with [Pb(II)] 1 mg/L=5 L). Finally, the chemical characterization in terms of CQO, TOC and phenolic compounds of the effluent before discharge showed that all values were lower than the ones allowed by environmental legislation