949 resultados para Logic of action
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Dissertação para obtenção do Grau de Doutor em Engenharia Electrotécnica e de Computadores
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High-content analysis has revolutionized cancer drug discovery by identifying substances that alter the phenotype of a cell, which prevents tumor growth and metastasis. The high-resolution biofluorescence images from assays allow precise quantitative measures enabling the distinction of small molecules of a host cell from a tumor. In this work, we are particularly interested in the application of deep neural networks (DNNs), a cutting-edge machine learning method, to the classification of compounds in chemical mechanisms of action (MOAs). Compound classification has been performed using image-based profiling methods sometimes combined with feature reduction methods such as principal component analysis or factor analysis. In this article, we map the input features of each cell to a particular MOA class without using any treatment-level profiles or feature reduction methods. To the best of our knowledge, this is the first application of DNN in this domain, leveraging single-cell information. Furthermore, we use deep transfer learning (DTL) to alleviate the intensive and computational demanding effort of searching the huge parameter's space of a DNN. Results show that using this approach, we obtain a 30% speedup and a 2% accuracy improvement.
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Candida albicans is an opportunistic human pathogen that is capable of causing superficial and systemic infections in immunocompromised patients. Extracts of Sapindus saponaria have been used as antimicrobial agents against various organisms. In the present study, we used a combination of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to identify the changes in protein abundance of C. albicans after exposure to the minimal inhibitory concentration (MIC) and sub-minimal inhibitory concentration (sub-MIC) of the butanolic extract (BUTE) of S. saponaria and also to fluconazole. A total of six different proteins with greater than 1.5 fold induction or repression relative to the untreated control cells were identified among the three treatments. In general, proteins/enzymes involved with the glycolysis (GPM1, ENO1, FBA1), amino acid metabolism (ILV5, PDC11) and protein synthesis (ASC1) pathways were detected. In conclusion, our findings reveal antifungal-induced changes in protein abundance of C. albicans. By using the previously identified components of the BUTE of S. saponaria(e.g., saponins and sesquiterpene oligoglycosides), it will be possible to compare the behavior of compounds with unknown mechanisms of action, and this knowledge will help to focus the subsequent biochemical work aimed at defining the effects of these compounds.
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Review of the early literature as well as more recent results show that sulfonamides possess a distinct antimalarial activity. However, when give alone, their action is less marked and slower than that of the antimalarials commonly used in the treatment of the acute attack. Combinations with pyrimethamine provide better results, even in cases of pyrimethamine and chloroquine resistance. This warrants further investigations in an attempt to develop a therapeutic agent suitable for the treatment of such resistant cases. It may also be possible with an appropriate combination of pyrimethamine with a sulfonamide to achieve a satisfactory method for suppressive treatment both in areas with and without pyrimethamine resistance. Three main points must still be carefully studied: 1) the risk of developing malaria resistance against one or both of the components of the combination. 2) The risk of developing bacterial resistance to sulfonamides if these substances are used on a large scale in too low doses. It seems indeed that antimalarial effect with the combination of sufonamides + pyrimethamine can be obtained with doses of sulfonamides which are below those usually employed in bacterial diseases. Since the range of the ratios providing potentiation is rather large, only ratios of the combination sulfonamides: pyrimethamine should be chosen in which an antfbacterial sulfonamidemia is guaranteed. 3) It goes without sayinq that, although both pyrimethamine and modem sulfonamides, when given by themselves, have proved tc possess a large margin of safety, long term administration of their combination should be careful studied from the point of view of possible side effects. Substantial evidence has already been produced to show that the long acting sulfonamide Fanasil (Ro 4-4393) given once or once weekly possesses marked schizonticidal activity against P. falciparum. Although its action is slower than that of 4-aminoquinolines, it may be useful as a second choice drug in semi-immune subjects for the therapy of falciparum malaria. Preliminary results show that, when combined with pyrimethamine, Fanasil is highly effective in suppressing fever and asexual parasitemia due to P. falciparum. Single doses of 1 g Fanasil together with 50 mg pyrimethamine seem to be adequate for the treatment of acute falciparum malaria in semi-immune patients. The onset of action of the combination is much more rapid than that of the single components. Weekly doses of 500 mg Fanasil and 25 mg pyrimeihamine appear to provide satisfactory suppressive effects against P. falciparum at least in East Africa. This combination is active on strains which do not respond satisfactorily to the standard doses of pyrimethamine and/or chloroquine and seems to have a satisfactory sporontocidal effect. Preliminary results indicate that Fanasil alone cannot be recommended for use against the other human malaria parasites. The combination with pyrimethamine appears to be much more effective. East African strains of P. malariae seem to respond better to the combination than do Malayan strains of P. vivax but further trials are required before definite assessment can be made. Fanasil by itself has no gametocytoddal or sporontocidal action but seems to potentiate the effect of pyrimethamine at least on sporogony of P. falciparum.
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Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics
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Trabalho de Projecto apresentado para cumprimento dos requisitos necessários à obtençao do grau de Mestre em Didáctica do Inglês,
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Dissertação para a obtenção do Grau de Mestre em Engenharia Biomédica
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Using a green methodology, 17 different poly(2-oxazolines) were synthesized starting from four different oxazoline monomers. The polymerization reactions were conducted in supercritical carbon dioxide under a cationic ring-opening polymerization (CROP) mechanism using boron trifluoride diethyl etherate as the catalyst. The obtained living polymers were then end-capped with different types of amines, in order to confer them antimicrobial activity. For comparison, four polyoxazolines were end-capped with water, and by their hydrolysis the linear poly(ethyleneimine) (LPEI) was also produced. After functionalization the obtained polymers were isolated, purified and characterized by standard techniques (FT-IR, NMR, MALDI-TOF and GPC). The synthesized poly(2-oxazolines) revealed an unusual intrinsic blue photoluminescence. High concentration of carbonyl groups in the polymer backbone is appointed as a key structural factor for the presence of fluorescence and enlarges polyoxazolines’ potential applications. Microbiological assays were also performed in order to evaluate their antimicrobial profile against gram-positive Staphylococcus aureus NCTC8325-4 and gram-negative Escherichia coli AB1157 strains, two well known and difficult to control pathogens. The minimum inhibitory concentrations (MIC)s and killing rates of three synthesized polymers against both strains were determined. The end-capping with N,N-dimethyldodecylamine of living poly(2- methyl-2-oxazoline) and poly(bisoxazoline) led to materials with higher MIC values but fast killing rates (less than 5 minutes to achieve 100% killing for both bacterial species) than LPEI, a polymer which had a lower MIC value, but took a longer time to kill both E.coli and S.aureus cells. LPEI achieved 100% killing after 45 minutes in contact with E. coli and after 4 hours in contact with S.aureus. Such huge differences in the biocidal behavior of the different polymers can possibly underlie different mechanisms of action. In the future, studies to elucidate the obtained data will be performed to better understand the killing mechanisms of the polymers through the use of microbial cell biology techniques.
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Part of the results presented in this thesis were published in the following reference (DOI 10.1016/j.cell.2015.08.055): Wenwen Zeng*, Roksana M. Pirzgalska*, Mafalda M.A. Pereira, Nadiya Kubasova, Andreia Barateiro, Elsa Seixas, Yi-Hsueh Lu, Albina Kozlova, Henning Voss, Gabriel G. Martins, Jeffrey M. Friedman and Ana I. Domingos. Sympathetic Neuro-adipose Connections Mediate Leptin-Driven Lipolysis. Cell 163, 84-94 (2015). The work was also presented through poster presentations at iMED Conference 6.0 (Lisbon, 2014), Sociedade Portuguesa de Bioquímica Meeting (Coimbra, 2014) and Sociedade Portuguesa de Neurociências Meeting (Póvoa de Varzim, 2015).
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Degeneration (WetAMD) and Diabetic Macular Edema (DME) patients’ access to treatment in public hospitals, by identifying bottlenecks and stress points that prevent timely and adequate care to patients who suffer from a degenerative disease, and consequently for whom the lack of access to treatment can have disastrous consequences. Considering the specificity and degenerative traits of these conditions, the long queues for specialty appointments in public hospitals are a significant threat to patients’ health, as the disease may be misdiagnosed and or progress significantly, causing unnecessary permanent and non-reversible loss in visual acuity. Therefore optimizing the patient journey will increase patients’ access to adequate treatment, and prevent avoidable progress of a degenerative condition which causes permanent and non-reversible blindness. Following the investigation which supports this thesis, the patient journey was broken down into its different phases, so that key issues could be identified, and referred back to the main stress points highlighted during the interviews with physicians and administrators. Finally results were scrutinized and systematized, and a set of action points was proposed, considering what may cause major impact and is actually feasible to implement.
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RESUMO: Arl13b é uma importante proteína ciliar, presente em cílios primários e cílios móveis. Ratinhos mutantes para Arl13b têm comprimento dos cílios reduzido e defeitos nos B-túbulos dos cílios. Como consequência destes fenótipos, deficiências na Arl13b originam, em modelos animais, várias doenças congénitas, incluindo problemas no estabelecimento do eixo esquerda-direita, malformações cerebrais e deformações corporais. Nos seres humanos, deficiências na Arl13b levam a uma doença crónica congénita chamada Síndrome de Joubert. Por outro lado, a sobreexpressão de Arl13b origina cílios mais longos, no entanto existe uma ausência da caracterização dos fenótipos celulares e durante o desenvolvimento embrionário. Neste trabalho, quisemos explorar o efeito da sobre-expressão de Arl13b em embriões de peixezebra. Descobrimos que, ao nível ciliar, a sobre-expressão de Arl13b nas células aumenta o comprimento ciliar em cílios primários e móveis, no entanto, a esses cílios falta adequada acetilação da alfa-tubulina no citoesqueleto feito por microtúbulos. Os nossos resultados mostraram que esse efeito é específico de Arl13b sobre-expressão e quando se manipularam as enzimas responsáveis pela acetilação (Mec17) e pela de-acetilação (HDAC6) encontrámos uma sinergia potencial com ambas. Testámos ainda, que o aumento no comprimento ciliar não estava causalmente relacionado com a falta de acetilação, ou seja, os cílios com menos acetilação não eram necessariamente os mais longos. Também mostrámos que a sobre-expressão de Arl13b é capaz de restaurar o comprimento dos cílios em mutantes com cílios curtos e como isso pode ser explorado para um futuro potencial papel terapêutico para Arl13b. Em seguida, foi avaliado o impacto do aumento da quantidade de Arl13b no desenvolvimento embrionário do peixe-zebra. Observou-se que a sobre-expressão de Arl13b apresentava fenótipos muito fracos, quando comparados com a perda de função dos mutantes de Arl13b. Focados no inesperado fenótipo leve no estabelecimento do eixo esquerda-direita abordámos a questão através do estabelecimento de uma colaboração com matemáticos, descobrimos que os cílios mais longos que potencialmente têm a capacidade de movimentar mais fluido são atenuados por amplitudes de batimento menores, e, como resultado, estes longos cílios não prejudicam o movimento do fluido e consequentemente não afetam o estabelecimento dos padrões de esquerda-direita. Sugerimos assim que a Arl13b é um regulador chave, do comprimento ciliar. Descobrimos uma nova interação com as enzimas de acetilação/de-acetilação e levantamos novas hipóteses quanto aos mecanismos moleculares da função da Arl13b. Propomos um novo modelo para o mecanismo molecular da Arl13b na regulação do comprimento dos cílios onde podemos integrar os nossos resultados com os relatados na literatura. Este trabalho adiciona mais conhecimento para o mecanismo de ação da Arl13b e, portanto, fornece uma importante contribuição para o campo da investigação em cílios.---------------------------------------------------------------------------------------------------------------------- ABSTRACT: Arl13b is an important ciliary protein, present in primary and motile cilia. arl13b-/- mouse mutants have reduced cilia length and cilia B-tubule defects. As a consequence of these phenotypes, Arl13b loss of function animal models suffer from several congenital disorders including left-right problems, brain malformations and body deformations. In humans Arl13b depletion leads to a congenital chronic disease called Joubert Syndrome. On the other hand, overexpressing Arl13b leads to longer cilia but the characterization of the cellular and developmental phenotypes was missing. In this work we explore the effect of Arl13b overexpression in zebrafish embryos. We found that, at the ciliary level, Arl13b overexpression from 1 cell stage produces longer primary and motile cilia, but these cilia lack proper alpha tubulin acetylation of their microtubule cytoskeleton. Our results showed that this effect is specific from Arl13b overexpression and when we manipulated the enzymes responsible for acetylation, Mec17, and de-acetylation, HDAC6, we found a potential synergy of both mec17 knockdown and HDAC6 activity with Arl13b overexpression. We tested that the ciliary increase in length was not causally related to the lack of acetylation, meaning the more de-acetylated cilia were not necessarily the longer ones. We also showed that Arl13b overexpression is able to restore cilia length in short cilia mutants and how that may be explored to a potential future therapeutic role for Arl13b. Next, we evaluated the impact of increasing the amount of Arl13b in zebrafish embryonic development. We observed that Arl13b overexpression presented very mild phenotypes when compared to the loss of function mutants. We focused on the unexpected left-right mild phenotype and by establishing a mathematical modeling collaboration, we found out that the longer cilia generated force was attenuated by smaller beating amplitudes, and as a result, these long cilia were not impairing the cilia generated flow and the establishment of left-right patterning. We suggest that Arl13b is one key cilia length regulator. We disclosed a novel interaction with the acetylation / de-acetylation enzymes and raised new hypothesis as to the mechanisms of Arl13b function. We propose a new model for the Arl13b molecular mechanism of cilia length regulation where we integrate our findings with those reported in the literature. This work adds more knowledge to the Arl13b mechanism of action and therefore provides an important contribution to the cilia research field.
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Information security is concerned with the protection of information, which can be stored, processed or transmitted within critical information systems of the organizations, against loss of confidentiality, integrity or availability. Protection measures to prevent these problems result through the implementation of controls at several dimensions: technical, administrative or physical. A vital objective for military organizations is to ensure superiority in contexts of information warfare and competitive intelligence. Therefore, the problem of information security in military organizations has been a topic of intensive work at both national and transnational levels, and extensive conceptual and standardization work is being produced. A current effort is therefore to develop automated decision support systems to assist military decision makers, at different levels in the command chain, to provide suitable control measures that can effectively deal with potential attacks and, at the same time, prevent, detect and contain vulnerabilities targeted at their information systems. The concept and processes of the Case-Based Reasoning (CBR) methodology outstandingly resembles classical military processes and doctrine, in particular the analysis of “lessons learned” and definition of “modes of action”. Therefore, the present paper addresses the modeling and design of a CBR system with two key objectives: to support an effective response in context of information security for military organizations; to allow for scenario planning and analysis for training and auditing processes.
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Doctoral Thesis (PhD Programm on Molecular and Environmental Biology)
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This article describes the evaluation of a psychological intervention—the Career Self-Management Seminar, Version A, for undergraduate students, and Version B for postgraduate students—developed to support Portuguese college students in career exploration, goal setting, design and implementation of action plans, and decision-making. A total of 120 participants from CSMS-A (experimental group, n = 58; control group, n = 62) and 98 from CSMS-B (experimental group, n = 62; control group, n = 36) were assessed by the Career Exploration Survey according to a pretest and posttest plan. Results demonstrate a significant increase in most of the cognitive, behavioral, and affective career exploration dimensions among the CSMS-A and CSMS-B experimental groups.