Fluorescent-based dendrimers as potential drug delivery carriers of cisplatin : from design and synthesis to platinum-membrane interactions

Tese de doutoramento, Farmácia (Tecnologia Farmacêutica), Universidade de Lisboa, Faculdade de Farmácia, 2018Dendrimers are a class of polymers with high potential as drug delivery systems due to their unique scaffold and properties. Despite their early potential, dendrimer-based therapies have been limited in part due to the considerable lack of understanding of their in vivo behavior and in particular, how they interact and cross cellular membranes. Therefore, designing dendrimers with an attached fluorophore would allow their tracking while studying their behavior with lipid bilayers. This work explores the potential of fluorescent dendrimers as carriers for the anti-cancer drug cisplatin, which is known to interact with lipids and induce phase changes in cellular membranes. To this end, fluorescent poly(glutamic acid) (PG) dendrimers were designed in silico and suitable candidates were attempted to be synthesized. Furthermore, effects of cisplatin in phase change and integrity of lipid model bilayers was studied to further drive the design of these dendrimers. The choice of PG dendrimers backbone was driven by their ability to fully cover a small fluorophore from the external environment. To quickly generate dendrimers scaffolds a set of computational tools were created to automate this process and facilitate the modeling of any class of dendrimers. Different generations and architecture of PG dendrimers with a fluorophore attached to the core and different terminal groups were created and submitted to all-atom simulations. Data from molecular dynamics showed that generation 4 was necessary to fully cover a low molecular weight fluorophore and partially cover a high molecular weight fluorophore as measured by the solvent accessible surface area. However, the synthesis of these candidates was shown to be difficult due to the amount of side reactions and possible steric hindrance that arises at high generations. Furthermore, the attachment of NBD was required to be carried out at lower generations since its reactivity with higher generations of PG dendrimers was lower. Therefore, analogues of glutamic acid with NBD (nitrobenzoxadiazole) were synthesized to be used as the initial core. Finally, platinum membrane interactions were characterized by measuring the fluorescence anisotropy of different probes embedded in liposomes composed of different lipid mixtures. Results suggested that both cisplatin and its cationic aquated analogue had low perturbation on the lipid phase and integrity of model membranes. However, cisplatin was able to further reduce the membrane fluidity when a gel phase was present in the membrane. Furthermore, at high concentrations, platinum complexes were shown to compromise the permeability of lipid bilayers without inducing collapse of the membrane. This effect was again dependent on membrane lipid composition. Altogether, these findings were used as a proof-of-concept for designing dendrimers as potential tools to carry and study cisplatin interactions at the lipid membrane

Mergers & acquisitions research: A bibliometric study of top strategy and international business journals, 1980–2010

Mergers and acquisitions (M&As) are important modes through which firms carry out their domestic and international strategies and have been noted as the CEOs favorite strategy. As a significant field of study, M&Aresearch has accumulated substantial knowledge. This bibliometric study examines the extant strategy and international business literature on M&As. Methodologically, we examined a sample of 334 articles published in sixteen leading management/business journals, during a 31 year period — from 1980 to 2010. The results provide a global perspective of the field, identifying the works that have had the greater impact, the intellectual interconnections among authors and works, the main research traditions, or themes, delved upon on M&Arelated research. Structural and longitudinal analyses reveal the changes in the intellectual structure of the field over time. A discussion on the accumulated knowledge and future research avenues concludes this paper.info:eu-repo/semantics/publishedVersio

International Business Research: Understanding Past Paths to Design Future Research Directions

In this paper we examine the extant research in IB by conducting a bibliometric study of the articles published in three leading international business journals – International Business Review, Journal of International Business Studies and Management International Review, over their entire track record of publication available in the ISI – Institute for Scientific Information. In longitudinal analyses of citation data we ascertain the most relevant works to the international business field. We also identify intellectual interconnectedness in co-citation networks of the research published in each journal. A second-tier analysis delves into publication patterns of those articles that are not at the top citation listings. Our results permit us better understand and depict the extant international business research and, to some extent, its evolution thus far.info:eu-repo/semantics/publishedVersio

Flow, synchronization and leveling

Estágio realizado no Instituto Kaizen e orientado pelo Eng.º José Carlos PiresTese de mestrado integrado. Engenharia Industrial e Gestão. Faculdade de Engenharia. Universidade do Porto. 200

Integration of EPANET in spatial database management system PostgreSQL/PostGIS: UrbanWater

Dissertação de Mestrado em Engenharia Geográfica, apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraA definição de metodologias de gestão e operação mais eficientes de um sistema de abastecimento de água (SAA) não pode hoje em dia deixar de passar pela adoção de Sistemas de Informação Geográfica (SIG) dada a natureza espacial da informação decorrente da sua atividade. A partir de um SIG a informação pode ser utilizada para a construção e desenvolvimento de modelos de simulação hidráulica. Estes constituem uma ferramenta de apoio para a Entidade Gestora (EG) no projeto e operação de um SAA. A construção e atualização de um modelo hidráulico pode ser um processo moroso e consumidor de recursos. A atualização da informação cadastral torna o modelo desajustado e consequentemente menos rigoroso. A existência de duas bases de dados, uma para o cadastro e outra referente ao modelo, obriga a um esforço adicional da EG na sua manutenção. Apesar da existência de soluções destinadas à modelação hidráulica, dotadas de funcionalidades de ligação e uso da informação armazenada num SIG estas representam custos adicionais, podendo deter menor flexibilidade face a procedimentos existentes na EG ou a satisfazer novas necessidades. A presente dissertação teve como objetivo a definição de um modelo de dados destinado a caracterizar as componentes do SAA e a integração da capacidade de modelação hidráulica, baseada no modelo EPANET 2, no Sistema de Gestão de Base de Dados (SGBD) open source PostgreSQL, dotado da extensão espacial PostGIS. O sistema desenvolvido permite a construção do modelo, a corrida da simulação hidráulica e armazenamento dos resultados numa base de dados única. Os procedimentos e funções necessárias foram escritos em pgSQL ou Python, sendo a sua execução levada a cabo pelo uso de instruções SQL, permitindo ao utilizador a seleção entre diferentes front-ends ou aplicações SIG Desktop. Por fim efetuou-se uma aplicação prática do sistema desenvolvido, considerando-se o SAA de Casal do Ribeiro (Ourém), gerido pela Be Water S.A.. O sistema desenvolvido mostra que uma abordagem integrada permite a criação de um modelo hidráulico de modo expedito a partir da informação cadastral armazenada, possibilitando o mapeamento dos resultados obtidos e a criação de consultas ou vistas mediante a utilização das capacidades do SGBD.The establishment of more efficient management and operating approaches of a water supply system, cannot be done nowadays without the use of Geographical Information Systems (GIS). This fact is due to the spatial nature of data used and produced by the water utility. Within a GIS, the data could be used to develop and construct a hydraulic models. These are fundamental tools to support the design and operation of a water supply system. The construction and maintenance of a hydraulic model can be both a time and resource consuming process. The water supply data updating process renders the hydraulic model obsolete so less accurate. Using two databases, one for the GIS and another for the model, requires additional data updating efforts. In spite of the existence of hydraulic modeling softwares capable of connecting and importing GIS data, these solutions represent additional costs and may have lower flexibility to water utility existing procedures or sustaining future needs. This MSc dissertation aimed to design and implement a data model capable of characterizing water system’s main components and to integrate EPANET based hydraulic model into the open source database management system (DBMS) PostgreSQL, along with spatial extension PostGIS. The developed system is capable of assembling a hydraulic model, running a simulation and storing the results in a single database. The implemented procedures were coded in pgSQL or Python and can be executed using SQL instructions. This permits the user to choose among different front-ends or GIS Desktop solutions. Finally, a case study was conducted where the developed system was applied to Casal Ribeiro water system (Ourém), managed by Be Water S.A.. The implemented system showed that an integrated approach provides a fast method to create a hydraulic model using stored GIS data, in mapping results, and in creating queries or views using the DBMS capabilities

Contributo para a análise do toleranciamento em SolidWorks™

A presente dissertação tem como objetivo analisar e compreender o funcionamento dos recursos de toleranciamento dimensional do software SolidWorks, contribuindo com docu mentação para a temática. Este trabalho surge devido à inexistência de documentação acerca dos módulos de toleranciamento e análise de tolerâncias deste software. A ausência desta documentação, aliada com a crescente adoção do uso de programas de CAD para o projeto de peças e sistemas mecânicos, aumenta a possibilidade da realização de um mau toleranciamento. As consequências de um mau toleranciamento podem ser desastrosas, especialmente a nível monetário, sendo importante a sua prevenção. Numa primeira fase, foi necessário realizar um levantamento das funcionalidades de cotagem e toleranciamento. Feito esse levantamento, abordou-se a configuração dos parâmetros que os caracterizam, seguido de uma breve demonstração da sua utilização. Na fase seguinte, procurou-se verificar de que modo a escolha de diferentes datums e métodos de modelação de peças iria influenciar os resultados. Para tal, recorreu-se a um caso de estudo simples. Na terceira fase, recorrendo a um novo caso de estudo, comparou-se as tolerâncias obtidas com a funcionalidade automática e as tolerâncias obtidas via uma síntese de tolerâncias. Esta comparação foi seguida de uma análise com recurso ao TolAnalyst. Do trabalho realizado, e tendo por base os ensinamentos retirados das fases anteriores, resultou uma metodologia que visa garantir a correta utilização destas funcionalidades. Foi possível ainda concluir que estas funcionalidades carecem sempre de uma cotagem e análise funcional, pois o SolidWorks não contempla esta possibilidade. O software dispõe de funcionalidades interessantes que permitem auxiliar o projetista, tendo um papel complementar na atribuição de cotas e tolerâncias.The main goal of this thesis is to analyze and understand the way how dimension tol erances are handled by SolidWorks, in order to contribute with documentation for the subject. This work was developed in order to suppress the lack of adequate documentation about the usage of the dimensioning and tolerancing tools, available in SolidWorks. The lack of this documentation, combined with the ever-growing usage of CAD softwares to design might lead to catastrophic results, especially moneywise. That being said, it’s important to prevent such thing from happening. The first step was to establish what tools were at our disposal. After establishing the tools, it was necessary to understand the settings behind such tools, followed by a quick demonstration. The second step consisted in finding out how did the datum choices and modelling methods influenced the results. This was achieved by means of a simple case study. The third step, was to compare the tolerancing obtained by the automatic tool and the tolerancing obtained by means of a tolerance synthesis, followed by an analysis using TolAnalyst. To do so, it was used another case study. This thesis resulted in developments regarding the documentation needed for a cor rect usage of the DimXpert tools. In order to compile all the information obtained during this dissertation, a methodology was developed, using flowcharts. This methodology aims to provide the user with important knowledge, to make good use of the tools available. Despite being helpful tools, they will still need to be combined with a functional analysis. SolidWorks helps the user by providing him useful tools to assist with the dimensioning and tolerancing of parts and mechanical systems

Evaluation of Encapsulation Potential of Selected Star-Hyperbranched Polyglycidol Architectures: Predictive Molecular Dynamics Simulations and Experimental Validation

Polymers, including non-linear copolymers, have great potential in the development of drug delivery systems with many advantages, but the design requires optimizing polymer–drug interactions. Molecular dynamics (MD) simulations can provide insights into polymer–drug interactions for designing delivery systems, but mimicking formulation processes such as drying is often not included in in silico studies. This study demonstrates an MD approach to model drying of systems comprising either hydrophilic tinidazole or hydrophobic clotrimazole drugs with amphiphilic hyperbranched copolyethers. The simulated drying protocol was critical for elucidating drug encapsulation and binding mechanisms. Experimentally, two polymers were synthesized and shown to encapsulate clotrimazole with up to 83% efficiency, guided by interactions with the hydrophobic core observed in simulations. In contrast, tinidazole is associated with surface regions, indicating capacity differences between drug types. Overall, this work highlights MD simulation of the drying process as an important tool for predicting drug–polymer complex behaviour. The modelled formulation protocol enabled high encapsulation efficiency and opened possibilities for the design of delivery systems based on computationally derived binding mechanisms. This demonstrates a computational–experimental approach where simulated drying was integral to elucidating interactions and developing optimized complexes, emphasizing the value of molecular modelling for the development of drug delivery formulations

Identificação Patogénica em Células Humanas Cancerígenas

Cerca de 15% a 20% dos cancros em humanos são devidos a infecções virais. Estas infecções, por vezes, têm a sua origem patogénica nas células humanas. A presença de vírus e bactérias nas células humanas, como Virus do Papiloma Humano, Hepatite B, entre outros, aumenta o risco e a probabilidade de contrair cancro. Estas bactérias/vírus são formadas a partir da tradução, nos ribossomas, das sequências mRNA, originando proteínas virais. O aumento de investimentos e esforços na área da Bioinformática, mais especificamente "Computational Transcriptomics" e "Sequencing and Genotyping Technologies", podem ajudar no estudo das infecções e agentes externos na formação de cancros.Atualmente, existem diversas ferramentas que ajudam na identificação de sequências não humanas presentes no RNA. Estas ferramentas, permitem a partir do mapeamento do RNA, diferenciar entre sequências do genoma humano e as bacteriais/virais. Estas ferramentas têm diferentes graus de eficácia dependendo da amostra e da finalidade da análise. Contudo, esta diferenciação, de maneira isolada, pouco contribui para o estudo e a identificação patogénica de sequências não humanas. Todo o processo de execução destas ferramentas tende a ser complexo e complicado para investigadores com parco conhecimento na àrea de Informática.Assim, como possível solução surge, a necessidade de fazer uma plataforma que de forma automática, processe o mapeamento e alinhamento do RNA com "datasets" bacteriais/virais. A solução proposta é uma plataforma online que com ligação a um pipeline num web service analise as amostras aplicando sucessivas ferramentas já existentes (Tophat, Bowtie2, Samtools). Este mapeamento, sendo ele iterativo e um filtro sucessivo, tem um grande peso computacional, sendo o tempo de processamento proporcional ao número de "reads". Com a comparação das sequências nos vários "datasets" é esperado que seja possível obter estatísticas de forma gráfica e de fácil compreensão sobre o mapeamento do gene de amostras. Será possível verificar regiões com um elevado RPKM (Reads Per Kilobase of transcript per Million mapped reads) e regiões do genoma onde há mais sequências com genes activos. A solução tem como objetivo ser uma ferramenta útil no estudo das infecções e agentes externos na formação de cancros.About 15% to 20% of cancers in humans are due to viral infections. These infections sometimes have their pathogenic origins in human cells. The presence of bacterias and viruses in human cells, such as human papillomavirus, hepatitis B, among other, increases the risk of developing cancer. These bacterias/viruses are formed from translation, at the ribosome, of the mRNA sequences, resulting in viral proteins.The investment and efforts in the area of Bioinformatics, specifically "Computational Transcriptomics" and "Sequencing and Genotyping Technologies", can help to understand the role of infections and external agents in the formation of cancers.Currently, there are several tools that help in the identification of non-human sequences present in the RNA. These tools allow from RNA mapping, differentiate the sequences between the human genome and bacterial/viral infections. These tools have different degrees of effectiveness depending on the sample and the purpose of the analysis. However, this differentiation, in isolation, does not have a big impact to the study and identification of non-pathogenic on human sequences. The whole process of implementation of these tools tend to be complex and difficult for researchers with a low level knowledge in the area of Informatics.As a possible solution for this problem arises the need to make a platform that automatically, does the mapping and alignment process of the RNA with bacterial/viral infections "datasets". The proposed solution is an online platform connected to a pipeline in a web service that analyzes the samples by applying successive existing tools (Tophat, Bowtie2, Samtools) on the user's sample. Being this mapping iterative and successive filter, it has a large computational weight,consume many resources, and the processing time is proportional to the number of "reads" to map. With the comparison of the sequences against the various "datasets" is expected to be possible to obtain graphic and understandable statistics of the samples gene's mapping . You can check genes with a high RPKM (Reads Per kilobase transcript of per Million mapped reads) and check regions of the genome where are a high number of active genes. The solution aims to be a useful tool in the study of infections and external agents in the formation of cancers

Revista de Bordo Digital

A revista de bordo é um produto editorial bem conhecido do passageiro aéreo. Ela faz parte do universo da aviação há várias décadas, servindo tanto o propósito de distrair os passageiros com medo de voar, como o de veicular artigos de viagem de qualidade a amantes deste tipo de narrativa. Mas a crise financeira de 2008 e o aumento do preço do petróleo começaram a mudar a maneira como os gestores das companhias aéreas olham para este produto tão familiar aos passageiros. O novo século traz novos desafios e põe em causa a continuação deste tipo de publicação, pelo custo que representa para as companhias e para o meio ambiente. Mas a evolução da tecnologia e a crise que o próprio jornalismo atravessa na transição para o online podem conter a chave para este problema. Uma publicação de bordo nativa digital pode oferecer potencialidades únicas aos passageiros, ao mesmo tempo que lidera o caminho da inovação jornalística