Browsing by Author "Fraga, Sónia"
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- Assessing the in vitro toxicity of airborne (nano)particles to the human respiratory system: from basic to advanced modelsPublication . Bessa, Maria João; Brandão, Fátima; Rosário, Fernanda; Moreira, Luciana; Reis, Ana Teresa; Valdiglesias, Vanessa; Laffon, Blanca; Fraga, Sónia; Teixeira, João PauloSeveral studies have been conducted to address the potential adverse health risks attributed to exposure to nanoscale materials. While in vivo studies are fundamental for identifying the relation-ship between dose and occurrence of adverse effects, in vitro model systems provide important information regarding the mechanism(s) of action at the molecular level. With a special focus on exposure to inhaled (nano)particulate material toxicity assessment, this review provides an over-view of the available human respiratory models and exposure systems for in vitro testing, advan-tages, limitations, and existing investigations using models of different complexity. A brief overview of the human respiratory system, pathway and fate of inhaled (nano)particles is also presented.
- Assessment of DNA damage in a group of professional dancers during a 10-month dancing seasonPublication . Esteves, Filipa; Teixeira, Eduardo; Amorim, Tânia; Costa, Carla; Pereira, Cristiana Costa; Fraga, Sónia; Moraes de Andrade, Vanessa; Teixeira, João Paulo; Costa, SolangeIntroduction: Professional dance is an activity with high artistic and physical demands. Requires physical athletic attributes such as muscular strength, endurance, coordination, agility and swiftness. Regular physical activity brings a lot of positive health-related outcomes. Reduce the risk of numerous health disorders like cardiovascular diseases, cancer, hypertension, diabetes, bone and joint diseases and it is responsible to maintain a numerous psychosocial benefits. However, intensive physical exercise is associated with an increased production of free radicals that may overcome the antioxidant system capacity to maintain homeostasis and may react with different biomolecules, e.g. deoxyribonucleic acid (DNA), inducing oxidative damage that may disturb the cell genomic integrity and cause a lot of diseases. The aim of the present study was to evaluate both DNA damage and oxidative stress in a group of professional dancers before and after a 10-month dancing season
- Assessment of DNA damage in a group of professional dancers during a 10-month dancing seasonPublication . Esteves, Filipa; Teixeira, Eduardo; Amorim, Tânia; Costa, Carla; Pereira, Cristiana Costa; Fraga, Sónia; Moraes de Andrade, Vanessa; Teixeira, João Paulo; Costa, SolangeDespite the numerous health benefits of physical activity, some studies reported that increased intensity and duration may induce oxidative stress in several cellular components including DNA. The aim of this study was to assess the level of basal DNA damage as well as oxidative DNA damage in a group of professional dancers before and after a 10-month dancing season. A group of individuals from general population was also assessed as a control. The alkaline version of the comet assay was the method selected to measure both basal DNA damage and oxidative stress, since this method quantifies both endpoints. In order to measure oxidative stress, the comet assay was coupled with a lesion-specific endonuclease (formamidopyrimidine glycosylase) to detect oxidized purines. The levels of oxidative DNA damage in dancers were significantly increased after the dancing season. Pre-season levels of oxidative DNA damage were lower in dancers than those obtained from the general population, suggesting an adaptation of antioxidant system in dancers. Results of the present biomonitoring study indicate the need for more effective measures to protect ballet dancers from potentially occupational health risks related to regular intensive physical exercise.
- Assessment of genotoxic effects of titanium dioxide nanoparticles on different human cell typesPublication . Fernández-Bertólez, Natalia; Brandao, Fátima; Rosário, Fernanda; Bessa, Maria João; Fraga, Sónia; Pásaro, Eduardo; Teixeira, Joao Paulo; Costa, Carla; Laffon, Blanca; Vanessa, ValdiglesiasThe main objective of the present work was to assess the cellular uptake and potential genotoxicity (micronuclei induction) of TiO2 NPs on four diverse human cell lines.
- Biocompatibility evaluation of CeO2 nanoparticles to be employed as nanodrugs in brain cancer nanomedicinePublication . Fernández-Bertólez, Natália; Touzani, Assia; Martínez, L.; Reis, Ana Teresa; Fraga, Sónia; Teixeira, João Paulo; Costa, Carla; Pásaro, Eduardo; Laffon, Blanca; Valdiglesias, VanessaCerium dioxide nanoparticles (CeO2NP) have recently gained attention for their unique structure-dependent properties, antioxidant enzyme-like behaviour, ROS scavenging activity and great potential for biomedical applications. In addition to their antioxidant and anti-inflammatory activity, CeO2NP are also known to exhibit anticancer potential, providing an attractive opportunity for use in cancer therapy, as a pharmacological agent and/or in drug/gene delivery systems [1]. Therefore, the main objective of this STSM was to evaluate the cytotoxic and genotoxic effects on human glioblastoma A172 cells exposed for 3, 24 and 48h to CeO2NP (1- 100µg/ml), to verify their safety to be used as possible nanomedicines for brain cancer treatment, specifically glioblastoma [2]. In addition, cell-specific differences in nanoceria effect were evaluated by comparing the results obtained with those observed in human neuronal SH-SY5Y cells exposed under the same experimental conditions. After carrying out the physicochemical characterization and analysing the cellular uptake of the CeO2NP, potential alterations in cell viability (MTT assay) and induction of DNA double-strand breaks (γH2AX assay) caused by the exposure were determined. The possible NP interference with assay methodologies was previously addressed and eliminated when necessary. Results obtained showed that, although there was a significant dose- and time-dependent internalization of NP by both cell types, nanoceria induced scarce cytotoxicity or genotoxicity in both cell lines, being restricted to the highest doses and longer exposure time tested. In general, data obtained suggest a high biocompatibility of CeO2NP under the tested conditions, except for glioblastoma cells exposed for 48h from 25 to 100µg/ml. These results provide a better understanding of the CeO2NP interaction with nervous system cells and their possible adverse effects. However, further studies are necessary to delve into the differential behaviour of these NP depending on the nervous cell type tested.
- Cell Model of Depression: Reduction of Cell Stress with MirtazapinePublication . Correia, Ana Salomé; Fraga, Sónia; Teixeira, João Paulo; Vale, NunoDepression is a very prevalent and complex disease. This condition is associated with a high rate of relapse, making its treatment a challenge. Thus, an intensive investigation of this disease and its treatment is necessary. In this work, through cell viability assays (MTT and neutral red assays) and alkaline comet assays, we aimed to test the induction of stress in human SH-SY5Y cells through the application of hydrocortisone and hydrogen peroxide and to test the reversal or attenuation of this stress through the application of mirtazapine to the cells. Our results demonstrated that hydrogen peroxide, and not hydrocortisone, can induce cellular stress, as evidenced by DNA damage and a global cellular viability reduction, which were alleviated by the antidepressant mirtazapine. The establishment of a cellular model of depression through stress induction is important to study new possibilities of treatment of this disease using cell cultures.
- Chemical characterization and in vitro cyto- and genotoxicity of ‘legal high’ products containing Kratom (Mitragyna speciosa)Publication . Oliveira, Ana Sofia; Fraga, Sónia; Carvalho, Félix; Araújo, Ana Margarida; Pereira, Cristiana Costa; Teixeira, João Paulo; de Lourdes Bastos, Maria; de Pinho, Paula GuedesKratom is a popular ‘legal high’ mainly constituted by alkaloids extracted from the Mitragyna speciosa plant with mitragynine (MG) as the dominant active substance. The increasing use of Kratom for recreational purposes has alerted risk assessment bodies of the lack of information on the real composition and its potential health risks. The present study aimed to determine and compare the MG composition of 13 commercial products of Kratom sold online and in “smartshops”, by gas chromatography–mass spectrometry. For the first time, the cytotoxicity induced by pure MG and Kratom, extracts was evaluated in in vitro models of human intestinal (Caco-2) and neuronal (SH-SY5Y) cells after 6 and 24 h. Genotoxicity was also evaluated in intestinal Caco-2 cells following 24 h of exposure to subtoxic concentrations using the comet assay. The obtained results revealed an inconsistency between the information (‘power’) provided in labels and the MG content. Cytotoxicity tests revealed a concentration-dependent decrease in cell viability in both cellular models, with the SH-SY5Y cells being more sensitive to the Kratom extracts. The resin and the ‘powered extracts’ were the most cytotoxic samples, with IC50 values significantly lower than the leaf extracts and pure MG (P < 0.0001 vs. leaf extracts and MG). In addition, significant DNA damage was observed in Caco-2 cells exposed to these extracts but not to pure MG, which suggests that other substances present in the extracts or interactions involving Kratom components might be responsible for the observed effects.
- Comparative Analysis of the Toxicity Profile of Eleven Consumer-Relevant Nanomaterials in Human Intestinal and Placental Barrier CellsPublication . Pires, Joana; Moreira, Luciana; Teixeira, João Paulo; Fraga, SóniaBackground: The growing number of items incorporating nanomaterials (NM) has prompted considerable concerns about human health and safety [1]. Metal nanoparticles, inorganic non-metallic, and carbon-based NM are among the types with the highest market volume [2]. Objective: The purpose of this study was to determine the effect of chemical composition [Ag, Au, TiO2, SiO2, and graphene oxide (nano_GO)], primary size (10, 30 and 60 nm AgNP and AuNP), crystal structure (TiO2NP rutile/anatase and anatase), and surface coating (citrate and PEGylated AuNP) on potential toxicity to human intestinal (Caco-2) and placental (BeWo b30) epithelial cells. Methods: Changes in cell morphology, metabolic activity, plasma membrane integrity, intracellular ROS and ATP levels, and DNA integrity were assessed to investigate their potential toxicity at 24 h after exposure. Results: In both barrier models, the toxicity profile was similar, however placentalwere more sensitive than intestinal epithelial cells. Overall, NM may be ranked for cytotoxicity as AgNP > nano_GO > AuNP ~ TiO2NP ~ SiO2NP, with the effects becoming more evident at greater concentrations. The influence of size was more pronounced for AgNP than for AuNP, with the smaller nanoparticles producing higher cytotoxic effects. The cytotoxicity of AuNP was prevented by PEG capping. AgNP and nano_GO exposure markedly raised the levels of ROS, indicating that oxidative stress may play a role in their cytotoxicity. Except for 10 nm AuNP, every NM tested markedly increased intracellular ATP levels. One interesting finding was that a higher cytotoxic potential did not necessarily equate to a higher genotoxic potential, since only AgNP (classified as positive) and anatase TiO2NP (classified as equivocal) caused DNA damage. Conclusions: Our findings alert to the potential risks associated with human barriers exposure to NM, where the physicochemical properties are important determinants of their toxicity. Additional research is needed for a deeper understanding of NM impact on human barriers.
- Comparative assessment of the acute toxicity of commonly used metal nanoparticles in two in vitro models of human barriersPublication . Pires, J.; Moreira, L.; Teixeira, João; Fraga, SóniaMetal nanoparticles (M-NP) have application in several areas such as industry, environment, agriculture, and biomedicine. Consequently, human exposure to these nanosized materials is increasing, which raises serious concerns regarding their safety to the human health and the environment. Biological barriers are important lines of defence to xenobiotics, thus expected targets for M-NP. The present study investigated the in vitro toxicity of different types of M-NP in two cell models of biological barriers: human intestinal (Caco-2) and trophoblastic (BeWo clone b30) epithelial cells. Cells were exposed for 24 h to varied concentrations (0.8-48 µg/cm2) of M NP of different chemical composition (Au, Ag, TiO2), primary size (10, 30 and 60 nm), capping (citrate, PEG) and crystal structure (rutile, anatase) and toxicity assessed by determining changes in cell morphology, metabolic activity, plasma membrane integrity, generation of intracellular reactive oxygen species (ROS) and intracellular ATP levels. Our data show that the potential toxicity of the tested M-NPs is similar for both cell lines with AgNPs > AuNPs > TiO2NPs, being the effects more visible at higher concentrations. The influence of the size in the cytotoxic-induced effects was more evident for AgNP than for AuNP, with the smaller NP causing more toxicity, being the BeWo cells more sensitive to these M-NP. In addition, PEG-capping effectively attenuated AuNP-induced toxicity both in Caco-2 and BeWo cells. Only cells exposed to AgNP exhibited significant increased levels of ROS. Thus, our data support that the physicochemical properties of the nanomaterials, in this particular case of M-NP, is an important determinant of their cytotoxicity and that intestinal and trophoblastic cells exhibit different sensitivity to the tested M-NP. Future studies would be useful to further explore the effects of M-NP in the human barriers
- Cytotoxicity and DNA damage of a panel of manufactured nanomaterials in rat alveolar epithelial RLE-6TN cellsPublication . Brandão, Fátima; Fraga, Sónia; Costa, Carla; Bessa, Maria João; Haase, Andrea; Teixeira, João PauloMain goal: The aim of this study was to evaluate the cyto- and genotoxicity of a panel of MNMs, including SiO2 NPs, graphene oxide, and nano-sized pigments in rat alveolar epithelial cells (RLE-6TN), a primary target following inhalation exposure.