Browsing by Issue Date, starting with "2025-04-16"
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- Assessing the pro inflammatory effects of bisphenol compounds using exposure relevant in vitro co culture modelsPublication . Pereira, Gonçalo Alexandre Candeias; Jordan, Peter; Rodrigues, CecíliaA inflamação atingiu proporções epidémicas nos países industrializados, principalmente devido a hábitos pouco saudáveis, má alimentação, poluição ambiental e outros fatores ainda não compreendidos. Quando descontrolada ou prolongada, a inflamação pode tornar-se crónica e contribuir para o desenvolvimento de várias doenças humanas, incluindo doenças autoimunes, doenças intestinais e, nos piores casos, tumorigénese e progressão tumoral. A exposição a disruptores endócrinos (EDCs) é um dos fatores ambientais que contribuem para a inflamação, e estudos recentes trouxeram o grupo dos bisfenóis (BP) para o centro das atenções científicas. Estes compostos têm sido fortemente associados a várias patologias, incluindo inflamação crónica, e o seu efeito na saúde intestinal humana é um tema de grande interesse na atualidade científica. Tendo isto em conta, o objetivo deste trabalho foi analisar os efeitos de quatro bisfenóis – BPA, BPS-MAE, BPAP e BPP – no stress da barreira intestinal e nos efeitos pró-inflamatórios associados. Para tal, foi otimizado e estabelecido um sistema de co-cultura, consistindo num protocolo melhorado de células epiteliais polarizadas Caco-2, semeadas em filtros de inserção PET no compartimento apical, juntamente com macrófagos derivados de monócitos THP-1 no compartimento basolateral. Posteriormente, foram testados os efeitos da exposição aos BPs na integridade da barreira, no stress celular e nas citocinas pró-inflamatórias, numa ampla gama de concentrações (de 100 µM a 0,1 µM). Experimentalmente, verificámos que o modelo foi capaz de fornecer dados específicos sobre os potenciais efeitos dos BPs na saúde. Em termos de resistência transepitelial e stress epitelial, conseguimos identificar algumas tendências claras que precisam de ser consolidadas com mais réplicas experimentais independentes. Em particular, o BPA foi o indutor menos potente de respostas de stress celular e alterações na polarização epitelial, enquanto os análogos de BP testados mostraram ser mais disruptivos do que o BPA, com o BPP a revelar-se potencialmente o mais perigoso, seguido do BPAP e por último o BPS-MAE. Para avaliar os efeitos moduladores da inflamação desses compostos, testámos macrófagos, tanto diretamente como em co-cultura, para a expressão do marcador pró-inflamatório IL-1β, utilizando uma abordagem de RT-PCR semi-quantitativa. Uma otimização importante foi a sua pré-ativação com IFN-γ para aumentar a sensibilidade do modelo e permitir maior relevância fisiológica. As nossas observações mostraram que, mais uma vez, os novos BPs induziram efeitos mais severos em comparação com o BPA. O BPP revelou-se o indutor mais potente de inflamação, seguido do BPS-MAE. Ambos apresentaram níveis elevados do marcador IL-1β em todas as concentrações testadas. O BPAP e o BPA produziram efeitos mais atenuados, embora significativos em concentrações mais altas. Em conclusão, este trabalho forneceu-nos resultados fundamentais sobre estes análogos do BPA e os seus efeitos na saúde intestinal, acrescentando novos conhecimentos sobre a "nova geração" emergente de BPs e os seus potenciais efeitos adversos na saúde.
- Airbrush techniques in chromatic reintegrationPublication . Boavida, Margarida; Doménech García, Beatriz; Guerola Blay, Vicente; BAILÃO, ANAAirbrush techniques have been minimally addressed in the field of conservation and restoration. A review of existing literature reveals limited knowledge about their application, apart from their use in ceramics. This research explores the use of airbrushing as an alternative method for chromatic reintegration of tiles. The objective of this study is to investigate the effectiveness of airbrushing in achieving precise chromatic reintegration, using the tratteggio technique and “reglatino” as starting points. To reach this, several mock-ups were created to assess the most suitable methodologies for optimal results, noting their advantages and disadvantages. The most efficient methodology was then used on two 17th century tiles. This paper aims to reflect on the potential application of airbrushing in chromatic reintegration, showcasing one of its many possible uses.
- The calcium-binding protein S100B as a novel chaperone preventing Tau aggregation in Alzheimer’s diseasePublication . Moreira, Guilherme G.; Gomes, Cláudio Emanuel MoreiraAlzheimer's disease (AD), the foremost cause of dementia, is characterized by persistent neuroinflammation and amyloid- and tau protein aggregation. Notably, S100 proteins are upregulated in neurodegenerative conditions, including AD, where they localize in proximity to amyloid plaques and neurons with tau-containing neurofibrillary tangles (NFTs). This dissertation examines the role of S100B in modulating tau aggregation during the early stages of AD. Our findings reveal that S100B colocalizes with microtubule-bound tau and interacts dynamically with tau in a calcium-dependent manner, specifically targeting aggregation-prone segments within the repeat region. As a holdase-type chaperone, S100B inhibits tau aggregation at substoichiometric concentrations by suppressing secondary nucleation pathways, as confirmed through seeding assays and direct observation of S100B's interaction with tau oligomers and fibrils. Furthermore, S100B, consistent with its extracellular chaperone function, effectively inhibits proteopathic tau seeding. In exploring tau liquid-liquid phase separation (LLPS), identified as an early event in tau aggregation, we demonstrate that S100B inhibits tau condensation in a calcium-dependent manner, shifting the phase boundary to higher PEG concentrations. S100B integrates into tau droplets, stabilizing tau and reducing the formation of toxic aggregates, preserving the liquid-like properties of tau droplets. Additionally, S100B’s capacity to buffer Zn²⁺, mitigates Zn²⁺-induced tau LLPS. In subsequent investigations, we assessed the inhibitory effects of various S100 proteins on K18 aggregation. S100B and S100A1 were identified as the most potent inhibitors, while other S100 proteins demonstrated varying inhibition levels. Kinetic analyses revealed distinct preferences: S100B and S100A1 predominantly inhibited secondary aggregation pathways, while S100A9 targeted primary pathways. NMR studies mapped tau-binding regions for S100A1 across tau’s repeat domain, whereas S100A9 interacted with the PHF6 segment and the C-terminal region. S100A1 reduced the seeding activity of pre-formed K18 fibrils in tau-RD biosensor cells, whereas S100A9 was ineffective. These findings underscore the neuroprotective role of S100 proteins, particularly S100B, in tauopathies.
- Infill and retouching approach on painting on copper support, 1790-2022. Materials and techniquesPublication . Vega, Daniel Esteban; BAILÃO, ANAThe scarcity of literature on the methods and materials used to restore copper paintings underscores the historical significance of this research. This article provides an overview of the infills and retouching materials applied to paintings on this metallic support from 1790 to 2022. The research identifies at least eight historical written sources produced before 1899 and fifty-five contemporary sources produced between 1900 and 2022. The range of products and procedures applied varies from traditional materials like carbonate calcium mixture with animal glue to synthetic resins, and from using brushes to carving heat pencils for application, respectively. Exploring the diverse practices over the last two centuries will not only help conservators make informed decisions on which materials and techniques to use during painting on copper restoration, but will also aid scientists in accurately interpreting the data collected from these objects during scientific analyses.
- 7th international Meeting on Retouching of Cultural Heritage proceedingsPublication . BAILÃO, ANA; Boavida, MargaridaBetween 12th and 14th October 2023, the RECH Group organised the seventh international conference in Lisbon, in collaboration with the Faculty of Fine Arts of the University of Lisbon. Specialists from various fields of conservation gathered to discuss issues surrounding chromatic reintegration. The event took place over three days, featuring thirty-one presentations, demonstrations and two workshops. Experts from Croatia, Spain, Portugal, Turkey, Austria, Poland, Israel, Canada, Monaco, Belgium, Italy, Taiwan and Brazil participated. Interests and concerns regarding chromatic reintegration practices were shared, both from the perspective of decision-making and materials and execution techniques. A trend towards seeking more sustainable and less toxic approaches was observed throughout the event. We express our gratitude to all speakers and participants of the conference, to the sponsors and to the entire team at the Faculty of Fine Arts who hosted us. Special thanks to the Committee members for their support and contributions during the conference and to this publication. This publication represents a truly collaborative effort that we hope will assist the conservation and restoration community in developing their chromatic reintegration work.