Aplicação de BIM a Infraestruturas Ferroviárias. Controlo da qualidade na construção

O Building Information Modelling (BIM) é uma metodologia que serve para toda a indús-tria AECO (arquitetura, engenharia, construção e operação) e, como tal, permite a representação das características estruturais e funcionais de uma construção, incluindo atividades, entre outras informações. A característica principal do BIM é o sistema de modelação tridimensional que inclui a gestão, partilha e troca de dados durante todo o ciclo de vida de uma construção, onde cada elemento ou objeto possui informação sobre os seus dados físicos. A metodologia BIM permite conduzir a uma melhor coordenação e colaboração entre os intervenientes no projeto possibilitando o acesso, em simultâneo e em tempo real, ao modelo BIM, possibilitando uma rápida deteção de conflitos entre componentes e, como consequência, uma diminuição de cus-tos. No fundo, o BIM pretende dar um impulso favorável no sentido de padronizar a informação e facilitar a comunicação, partilhando e integrando eficazmente os intervenientes no processo construtivo. No âmbito da avaliação da capacidade de carga de infraestruturas ferroviárias e da respe-tiva vida útil, procura-se identificar quais as contribuições dos ensaios não destrutivos para o controlo da qualidade durante a construção de vias-férreas e executa-se uma retroanálise com recurso ao software BISAR 3. Os ensaios de carga não destrutivos possibilitam o estabeleci-mento de modelos de comportamento estrutural. Neste sentido, deseja-se desenvolver uma me-todologia mais expedita com base nos ensaios realizados in situ por forma a otimizar a análise estrutural das vias-férreas, constituindo assim uma alternativa para o controlo da qualidade. No que respeita às infraestruturas ferroviárias, pretende-se avaliar a aplicabilidade prática do conceito BIM na modelação estrutural e controlo da qualidade de uma via-férrea durante a construção. Com a metodologia BIM deseja-se demonstrar que esta pode ser implementada no sistema de gestão e monitorização de infraestruturas ferroviárias, possibilitando o registo das suas características físicas e geométricas, bem como os dados da medição da via, permitindo um controlo de qualidade da via-férrea após a construção, isto é, ao longo da sua vida útil

New Bis-Alkylation Reagents for Protein Conjugation

Bis-alkylation for disulfide-bridging PEGylation has emerged as a valid strategy for protein conjugation. Proteins can be efficiently modified to add a three-carbon methylene bridge between the two sulfurs in a disulfide bond. The so-called C3 bis-sulfone reagent is a linear poly (ethylene glycol) (PEG) that has been functionalised at one terminus with a latently reactive bis-alkylation moiety capable of undergoing sequential Michael reactions. Latency is achieved by utilising leaving groups that must undergo elimination to unmask an ,-unsaturated double bond needed for Michael addition. Structural modifications of these reagents are thought to alter the solvent availability or electrophilic character of the Michael acceptor to modulate conjugation reactivity with a protein. It was therefore hypothesised that by modifying the structure of C3 bis-sulfone reagent, it would be possible to obtain reagents with different reactivity. This variable reactivity can then be exploited with bifunctional reagents to allow the preparation of protein-protein conjugates in an efficient manner. Several synthetic targets and strategies were examined to prepare different types of di-PEG and multifunctional reagents for protein conjugates. A small family of di-PEG bis-alkylating reagents with different molecular weights was prepared and the conjugation efficiency was compared to linear C3 PEG reagents of the same overall molecular weight. Molecular dynamic studies were used to understand how the PEG chain affected the linker reactivity. Results showed that PEG-linker interactions were found to be less pronounced for reagents that contained two 10 kDa PEG chains (di-PEG2×10) when compared to a linear C3 reagent with a single PEG of 20 kDa (PEG20) with the same overall molecular weight. While the presence of a second PEG chain was found to influence conjugation efficiency, the modification of the bis-alkylating Michael acceptor in C3 reagent was also explored as a means to vary reactivity. Acetylenic ketones were examined as bis-Michael acceptors in the preparation of two C1 reagents with distinct structural features (aliphatic and aromatic). An aliphatic C1 reagent was prepared without leaving groups but was found to have less reactivity when compared to an aromatic C3 reagent. Semi-empirical studies suggested that this lower reactivity could be attributed to less electron-withdrawing aliphatic structure and to stereoelectronic effects. Aliphatic C1, while less reactive was found to undergo a double Michael addition and consequently allowed re-bridging of a reduced disulfide. In contrast, aromatic C1 required leaving groups to modulate the higher reactivity observed but was not found to re-bridge a reduced disulfide. The C3 bis-sulfone reagent is known to undergo elimination much more slowly at slightly acidic pH values. This is important because conjugation will not proceed until elimination has occurred. The need for elimination was used as a basis for the synthesis of hetero-bifunctional reagents that could be used for hetero-functional protein-protein conjugates, such as bispecific Fab-PEG-Fab conjugates. For potential scalability, effort was focused on preparing mono-sulfone-PEG-bis-sulfone hetero-bifunctional reagents (MpB reagents) that could be utilised in a one-pot reaction sequence to give hetero-functional protein conjugates. Reactions using the MpB reagent showed the potential to allow the sequential conjugation of two Fab molecules by altering the pH conditions of the reaction mixture in a single reaction vessel. This variable reactivity can provide a synthetic platform for controlled sequential conjugation that can allow the efficient preparation of protein-protein conjugates

MitraClip in tricuspid regurgitation : current evidence

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2022A Regurgitação Tricúspide afeta 65-85% da população e está associada a um risco de mortalidade consideravelmente elevado. As opções terapêuticas disponíveis para doentes de alto risco cirúrgico são limitadas. O MitraClip, previamente aprovado para a regurgitação mitral, é um dispositivo percutâneo promissor em investigação para o tratamento desta patologia. A presente dissertação pretende elucidar sobre os desenvolvimentos no uso do MitraClip na Regurgitação Tricúspide, desde estudos em modelo ex-vivo até estudos de imagem e ensaios clínicos. Mais ainda, descreve também a técnica de colocação do MitraClip e aborda os estudos mais recentes com enfoque neste dispositivo. Os estudos descritos no presente trabalho sugerem que a implementação do MitraClip é viável, segura e duradoura até pelo menos 1 ano em doentes de alto risco cirúrgico, demonstrando benefícios clínicos persistentes no tempo, nomeadamente, a redução do grau de regurgitação tricúspide, redução na Classificação Funcional da New York Heart Association e melhoria no teste de marcha de 6 minutos. A sua implementação em doentes de alto risco cirúrgico, para além de motivar um remodelling cardíaco reverso positivo e de ser mais vantajosa que a terapêutica médica isolada, não está associada a efeitos adversos cardíacos major. Não foram encontradas diferenças significativas no uso do MitraClip em abordagens isoladas à válvula tricúspide e em abordagens combinadas com correção de patologia mitral. Menores coaptation gaps e localização não central/antero-septal do jato de regurgitação foram identificados como preditores de sucesso do procedimento. Valores elevados de tenting area e de EROA foram definidos como preditores ecocardiográficos de insucesso. Indivíduos com o diagnóstico de Hipertensão Pulmonar confirmado invasivamente e por ecocardiografia apresentam valores de event-free survival time sobreponíveis aos de indivíduos sem Hipertensão Pulmonar sugerindo o possível potencial terapêutico das intervenções percutâneas nestas populações e a necessidade de redefinição de critérios de exclusão em estudos futuros.Tricuspid Regurgitation is a condition affecting 65-85% of the population that carries reasonable high mortality risk. Current treatment options are limited and far from ideal, particularly in high surgical risk patients. The development of new transcatheter devices may offer some therapeutic answers to some of these high risk patients. The MitraClip, previously approved for patients with mitral regurgitation, is a promising percutaneous device currently being tested for right heart disease. The present dissertation aims to shed light on how far we have come on the use of the MitraClip in Tricuspid Regurgitation, from ex-vivo studies to imaging studies and clinical trials. Moreover, it also describes the device’s procedural technique and outlines recent data on the studies using this transcatheter edge-to-edge device. The studies described suggest that MitraClip implementation is feasible, safe and durable over 1 year in patients at high prohibitive surgical risk with persistent clinical results over time, namely reduction in tricuspid regurgitation grade of severity and functional parameters such as NYHA Functional Class and 6-min walking test. Its use is associated with positive reverse cardiac remodeling but not with increased major adverse cardiac or cerebrovascular effects, comparing favorably to alone medical therapy. There are no significant differences on the use of the MitraClip in isolated tricuspid or combined mitral valve approaches. Small coaptation gaps as well as non-central/anteroseptal location of regurgitant jet are identified as predictors of procedural success, while greater tricuspid Tenting Area and larger EROA are defined as echocardiographic predictors of procedural failure. Patients with Pulmonary Hypertension confirmed invasively and echocardiographically had similar event-free survival time after MitraClip implantation in comparison to patients without Pulmonary Hypertension suggesting a need for redefinition of inclusion criteria in future studies and highlighting the potential role of transcatheter valve therapies in these patients

Dataset for "Re-engineering lysozyme solubility and activity through surfactant complexation"

This dataset contains data used in the generation of results for the paper " Re-engineering lysozyme solubility and activity through surfactant complexation" Hydrophobic ion-pairing is an established solubility engineering technique that uses amphiphilic surfactants to modulate drug lipophilicity and facilitate encapsulation in polymeric and lipid-based drug delivery systems. For proteins, surfactant complexation can also lead to unfolding processes and loss in bioactivity. This study aimed to understand the impact of two surfactants, sodium dodecyl sulphate (SDS) and dioctyl sulfosuccinate (DOSS) on lysozyme’s solubility, activity, and structure. Lysozyme lipophilicity was successfully increased, with log D n-octanol/PBS values up to 2.5 with SDS and 1.8 with DOSS. Bioactivity assays assessing lysis of M. lysodeikticus cell walls showed up to a 2-fold increase in lysozyme’s catalytic ability upon complexation with SDS at ratios less than stoichiometric, suggesting favourable mechanisms of stabilisation. Secondary structural analysis using Fourier-transform infrared spectroscopy indicated that lysozyme underwent a partial unfolding process upon complexation with low SDS concentrations. Combined, this suggested that sub-stoichiometric SDS altered the active site’s secondary structure through increased backbone flexibility, leading to higher substrate accessibility. For DOSS, low surfactant concentrations retained lysozyme’s native function and structure while still increasing the protein’s lipophilic character

Moving protein PEGylation from an art to a data science

[Image: see text] PEGylation is a well-established and clinically proven half-life extension strategy for protein delivery. Protein modification with amine-reactive poly(ethylene glycol) (PEG) generates heterogeneous and complex bioconjugate mixtures, often composed of several PEG positional isomers with varied therapeutic efficacy. Laborious and costly experiments for reaction optimization and purification are needed to generate a therapeutically useful PEG conjugate. Kinetic models which accurately predict the outcome of so-called “random” PEGylation reactions provide an opportunity to bypass extensive wet lab experimentation and streamline the bioconjugation process. In this study, we propose a protein tertiary structure-dependent reactivity model that describes the rate of protein-amine PEGylation and introduces “PEG chain coverage” as a tangible metric to assess the shielding effect of PEG chains. This structure-dependent reactivity model was implemented into three models (linear, structure-based, and machine-learned) to gain insight into how protein-specific molecular descriptors (exposed surface areas, pK(a), and surface charge) impacted amine reactivity at each site. Linear and machine-learned models demonstrated over 75% prediction accuracy with butylcholinesterase. Model validation with Somavert, PEGASYS, and phenylalanine ammonia lyase showed good correlation between predicted and experimentally determined degrees of modification. Our structure-dependent reactivity model was also able to simulate PEGylation progress curves and estimate “PEGmer” distribution with accurate predictions across different proteins, PEG linker chemistry, and PEG molecular weights. Moreover, in-depth analysis of these simulated reaction curves highlighted possible PEG conformational transitions (from dumbbell to brush) on the surface of lysozyme, as a function of PEG molecular weight

Automated prediction of site and sequence of protein modification with ATRP initiators

One of the most straightforward and commonly used chemical modifications of proteins is to react surface amino groups (lysine residues) with activated esters. This chemistry has been used to generate protein-polymer conjugates, many of which are now approved therapeutics. Similar conjugates have also been generated by reacting activated ester atom transfer polymerization initiators with lysine residues to create biomacromolecular initiators for polymerization reactions. The reaction between activated esters and lysine amino groups is rapid and has been consistently described in almost every publication on the topic as a “random reaction”. A random reaction implies that every accessible lysine amino group on a protein molecule is equally reactive, and as a result, that the reaction is indiscriminate. Nonetheless, the literature contradicts itself by also suggesting that some lysine amino groups are more reactive than others (as a function of pK(a), surface accessibility, temperature, and local environment). If the latter assumption is correct, then the outcome of these reactions cannot be random at all, and we should be able to predict the outcome from the structure of the protein. Predicting the non-random outcome of a reaction between surface lysines and reactive esters could transform the speed at which active bioconjugates can be developed and engineered. Herein, we describe a robust integrated tool that predicts the activated ester reactivity of every lysine in a protein, thereby allowing us to calculate the non-random sequence of reaction as a function of reaction conditions. Specifically, we have predicted the intrinsic reactivity of each lysine in multiple proteins with a bromine-functionalised N-hydroxysuccinimide initiator molecule. We have also shown that the model applied to PEGylation. The rules-based analysis has been coupled together in a single Python program that can bypass tedious trial and error experiments usually needed in protein-polymer conjugate design and synthesis

Can enzyme proximity accelerate cascade reactions?

The last decade has seen an exponential expansion of interest in conjugating multiple enzymes of cascades in close proximity to each other, with the overarching goal being to accelerate the overall reaction rate. However, some evidence has emerged that there is no effect of proximity channeling on the reaction velocity of the popular GOx-HRP cascade, particularly in the presence of a competing enzyme (catalase). Herein, we rationalize these experimental results quantitatively. We show that, in general, proximity channeling can enhance reaction velocity in the presence of competing enzymes, but in steady state a significant enhancement can only be achieved for diffusion-limited reactions or at high concentrations of competing enzymes. We provide simple equations to estimate the effect of channeling quantitatively and demonstrate that proximity can have a more pronounced effect under crowding conditions in vivo, particularly that crowding can enhance the overall rates of channeled cascade reactions