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Projeto de investigação
Egas Moniz Interdisciplinary Research Center
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The effects of different types of dual tasking on balance in healthy older adults
Publication . de Barros, Graça Monteiro; Melo, Filipe; Domingos, Josefa; Oliveira, Raul; Silva, Luís; Fernandes, Júlio Belo; Godinho, Catarina; DF – Departamento de Física; LIBPhys-UNL; MDPI - Multidisciplinary Digital Publishing Institute
Numerous of our daily activities are performed within multitask or dual task conditions. These conditions involve the interaction of perceptual and motor processes involved in postural control. Age-related changes may negatively impact cognition and balance control. Studies identifying changes related to dual-task actions in older people are need. This study aimed to determine the effects of different types of dual-tasking on the balance control of healthy older adults. The sample included 36 community-living older adults, performing two tests—a sway test and a timed up-and-go test—in three conditions: (a) single motor task; (b) dual motor task; and (c) dual motor task with cognitive demands. Cognitive processes (dual-task and cognition) affected static balance, increasing amplitude (p < 0.001) and frequency (p < 0.001) of the center of mass displacements. Dynamic balance revealed significant differences between the single motor condition and the other two conditions during gait phases (p < 0.001). The effect of dual-tasking in older adults suggests that cognitive processes are a main cause of increased variability in balance and gait when under an automatic control. During sit-to-stand, turning, and turn-to-sit movements under dual-tasking, the perceptive information becomes the most important focus of attention, while any cognitive task becomes secondary.
Polymerizable matrix metalloproteinases’ inhibitors with potential application for dental restorations
Publication . Laronha, Helena; Carpinteiro, Inês; Portugal, Jaime; Azul, Ana; Polido, Mário; Petrova, Krasimira T.; Salema-Oom, Madalena; Barahona, Isabel; Caldeira, Jorge; UCIBIO - Applied Molecular Biosciences Unit; LAQV@REQUIMTE; MDPI AG
Collagen cleavage by matrix metalloproteinase (MMP) is considered a major cause of dental resins long term failure. Most MMP inhibitors display significant toxicity and are unsuitable for dental resins’ applications. Here we report a study of a new class of inhibitors that display the unique property of being co-polymerizable with other vinyl compounds present in commercial dental resins, limiting their release and potential toxicity. Computational affinity towards the active site of different MMP-1;-2;-8;-9 and-13 of several compounds showed interesting properties and were synthesized. These free compounds were tested concerning their toxicity upon contact with two different cell types, with no substantial decrease in cell viability at high concentrations. Even so, compound’s safety can be further improved upon copolymerization with commercial dental resins, limiting their release.
Nitrite quantification in processed meat using an enzyme biosensor, a portable reader and a smartphone
Publication . Surace, Luca; Zumpano, Rosaceleste; Polli, Francesca; Gajdar, Július; Mazzei, Franco; Almeida, M. Gabriela; UCIBIO - Applied Molecular Biosciences Unit; DQ - Departamento de Química; Elsevier
The control of nitrite levels in foodstuff is essential for ensuring human safety. However, the protocols are long and require lab equipment (spectrophotometer and centrifuge) not available in industrial or commercial settings. Herein, we adapted an electrochemical nitrite biosensor utilizing the enzyme cytochrome c nitrite reductase (ccNiR) previously developed in our lab, to meet the analytical requirements of cured meats, and validated it using real samples from different brands. The enzyme was immobilized on a disposable carbon screen-printed electrode (SPE) modified with multi-walled carbon nanotubes (MWCNTs) and connected to a hand-held potentiostat coupled to a smartphone. The carbon nanotubes suspension was optimized using chemically friendly solvents and the SPE surface was electrochemically characterized using ferricyanide as a redox probe, to fine-tune the modification formulation. The nitrite biosensor delivered a sensitivity of 0.0103 μA/μM, a linear range from 5 to 100 μM, and a lower detection limit (LOD) of 3.2 μM. Subsequently, the biosensor was tested for its ability to detect nitrites in various processed meat samples, considering factors such as type and origin. The validation of the electrochemical biosensor was conducted using the gold standard Griess method and HPLC, although the first one failed to detect nitrites in some samples due to matrix interferences. Accordingly, the nitrite biosensor performed well, providing highly accurate and precise results (smaller SD), even in non-centrifuged samples, making it possible to control the meat quality at any point of the chain distribution.
Nitrite reduction in bacteria
Publication . Besson, Stéphane; Almeida, M. Gabriela; Silveira, Célia M.; LAQV@REQUIMTE; UCIBIO - Applied Molecular Biosciences Unit; Instituto de Tecnologia Química e Biológica António Xavier (ITQB); Elsevier
The last years have witnessed a steady increase of social and political awareness for the need of studying, monitoring, and controlling several anthropological activities that are dramatically impacting the environment and human health. The increasing turnover rates of the nitrogen cycle across the Planet are of major concern, so the understanding of the biological, chemical, and physical processes associated with the biogeochemical nitrogen cycle has been attracting the attention of several scientific disciplines. For many years, the primary focus has been the so-called “dissimilatory reduction of nitrate”, which refers to the stepwise conversion of nitrate into molecular nitrogen, closely followed by the assimilatory nitrate reduction pathway, which allow nitrogen incorporation into biomolecules. The contribution of bioinorganic chemists to better understand the enzymology underlying these two branches of the N-cycle has been remarkable. The constant development of mechanistic, structural, and biological tools has been keeping this bioinorganic chemistry field very active, making it a highly relevant research area still today. In this paper, we review the state-of-the-art in both dissimilatory and assimilatory nitrite reducing enzymes, highlighting the structural peculiarities of the different metalloenzymes involved in this step.
Point-of-care testing of nitrite in oral medicine
Publication . Gaspar, Sara Rodrigues; Proença, Luís; Alves, Ricardo; Almeida, Maria Gabriela; DQ - Departamento de Química; UCIBIO - Applied Molecular Biosciences Unit; Elsevier BV
Periodontal disease (PD) is a chronic inflammatory condition triggered by bacterial biofilms and progresses through two main stages: gingivitis and periodontitis. The existing diagnostic methods remain time-consuming and require clinical expertise. Salivary nitrite, a stable end-product of nitric oxide produced during inflammation, has emerged as a promising biomarker for PD. However, its reliable quantification in saliva typically relies on laboratory-based assays that are unsuited to clinical workflows. This study aimed to test and validate a new nitrite point-of-care test (POCT) for oral medicine. Building on previous research, we developed a biosensing platform based on screen-printed carbon electrodes modified with a selective enzyme, the cytochrome c nitrite reductase. To adapt bioelectrodes for salivary analysis, they were further modified with a poly(vinyl) alcohol coating and a biochemical oxygen scavenger system (ascorbate oxidase and ascorbate). The nitrite biosensor achieved a suitable linear range of 5–300 μM, with a sensitivity of 0.015 μM−1, validated against the gold-standard Griess method. Unlike the Griess reaction, the biosensor was unaffected by sample turbidity, rendering centrifugation unnecessary. Additionally, we observed that sample freezing altered nitrite concentrations, increasing levels in non-centrifuged samples, while decreasing them in previously clarified samples. These findings highlight the need for real-time analysis and call into question the reliability of previously published data that overlooked these variables. Therefore, our results demonstrate the potential of the nitrite biosensor as a novel salivary POCT and emphasize the critical need for standardized sample-handling protocols.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/04585/2020