Browsing by Author "Valdiglesias, V."
Now showing 1 - 10 of 11
Results Per Page
Sort Options
- An ECVAG inter-laboratory validation study of the comet assay: inter-laboratory and intra-laboratory variation of DNA strand breaks and FPG-sensitive sites in human mononuclear cellsPublication . Ersson, C.; Møller, P.; Forchhammer, L.; Loft, S.; Azqueta, A.; Godschalk, R.W.; van Schooten, F.J.; Jones, G.D.; Higgins, J.A.; Cooke, M.S.; Mistry, V.; Karbaschi, M.; Phillips, D.H.; Sozeri, O.; Routledge, M.N.; Nelson-Smith, K.; Riso, P.; Porrini, M.; Matullo, G.; Allione, A.; Stepnik, M.; Ferlińska, M.; Teixeira, João Paulo; Costa, S.; Corcuera, L.A.; López de Cerain, A.; Laffon, B.; Valdiglesias, V.; Collins, A.R.; Möller, L.The alkaline comet assay is an established, sensitive method extensively used in biomonitoring studies. This method can be modified to measure a range of different types of DNA damage. However, considerable differences in the protocols used by different research groups affect the inter-laboratory comparisons of results. The aim of this study was to assess the inter-laboratory, intra-laboratory, sample and residual (unexplained) variations in DNA strand breaks and formamidopyrimidine DNA glycosylase (FPG)-sensitive sites measured by the comet assay by using a balanced Latin square design. Fourteen participating laboratories used their own comet assay protocols to measure the level of DNA strand breaks and FPG-sensitive sites in coded samples containing peripheral blood mononuclear cells (PBMC) and the level of DNA strand breaks in coded calibration curve samples (cells exposed to different doses of ionising radiation) on three different days of analysis. Eleven laboratories found dose-response relationships in the coded calibration curve samples on two or three days of analysis, whereas three laboratories had technical problems in their assay. In the coded calibration curve samples, the dose of ionising radiation, inter-laboratory variation, intra-laboratory variation and residual variation contributed to 60.9, 19.4, 0.1 and 19.5%, respectively, of the total variation. In the coded PBMC samples, the inter-laboratory variation explained the largest fraction of the overall variation of DNA strand breaks (79.2%) and the residual variation (19.9%) was much larger than the intra-laboratory (0.3%) and inter-subject (0.5%) variation. The same partitioning of the overall variation of FPG-sensitive sites in the PBMC samples indicated that the inter-laboratory variation was the strongest contributor (56.7%), whereas the residual (42.9%), intra-laboratory (0.2%) and inter-subject (0.3%) variations again contributed less to the overall variation. The results suggest that the variation in DNA damage, measured by comet assay, in PBMC from healthy subjects is assay variation rather than variation between subjects.
- Analysis of cellular damage induced by silica-coated iron oxide nanoparticles on neuronal cellsPublication . Laffon, Blanca; Kiliç, G.; Fernandez Bertólez, N.; Costa, C.; Costa, S.; Teixeira, J.P.; Pásaro, E.; Valdiglesias, V.The objective of this work was to evaluate toxicity induced by silica-coated ION on a human neuronal cell line (SHSY5Y).
- Comparative study on effects of two different types of titanium dioxide nanoparticles on human neuronal cellsPublication . Valdiglesias, V.; Costa, C.; Sharma, V.; Kiliç, G.; Pásaro, E.; Teixeira, João Paulo; Dhawan, A.; Laffon, B.Titanium dioxide (TiO2) are among most frequently used nanoparticles (NPs). They are present in a variety of consumer products, including food industry in which they are employed as an additive. The potential toxic effects of these NPs on mammal cells have been extensively studied. However, studies regarding neurotoxicity and specific effects on neuronal systems are very scarce and, to our knowledge, no studies on human neuronal cells have been reported so far. Therefore, the main objective of this work was to investigate the effects of two types of TiO₂ NPs, with different crystalline structure, on human SHSY5Y neuronal cells. After NPs characterization, a battery of assays was performed to evaluate the viability, cytotoxicity, genotoxicity and oxidative damage in TiO₂ NP-exposed SHSY5Y cells. Results obtained showed that the behaviour of both types of NPs resulted quite comparable. They did not reduce the viability of neuronal cells but were effectively internalized by the cells and induced dose-dependent cell cycle alterations, apoptosis by intrinsic pathway, and genotoxicity not related with double strand break production. Furthermore, all these effects were not associated with oxidative damage production and, consequently, further investigations on the specific mechanisms underlying the effects observed in this study are required.
- Effects of iron oxide nanoparticles: Cytotoxicity, genotoxicity, developmental toxicity, and neurotoxicityPublication . Valdiglesias, V.; Kiliç, G.; Costa, C.; Fernández-Bertólez, N; Pásaro, E.; Teixeira, João Paulo; Laffon, B.Iron oxide nanoparticles (ION) with superparamagnetic properties hold great promise for use in various biomedical applications; specific examples include use as contrast agents for magnetic resonance imaging, in targeted drug delivery, and for induced hyperthermia cancer treatments. Increasing potential applications raise concerns over their potential effects on human health. Nevertheless, very little is currently known about the toxicity associated with exposure to these nanoparticles at different levels of biological organization. This article provides an overview of recent studies evaluating ION cytotoxicity, genotoxicity, developmental toxicity and neurotoxicity. Although the results of these studies are sometimes controversial, they generally indicate that surface coatings and particle size seem to be crucial for the observed ION-induced effects, as they are critical determinants of cellular responses and intensity of effects, and influence potential mechanisms of toxicity. The studies also suggest that some ION are safe for certain biomedical applications, while other uses need to be considered more carefully. Overall, the available studies provide insufficient evidence to fully assess the potential risks for human health related to ION exposure. Additional research in this area is required including studies on potential long-term effects.
- In vitro toxicity screening of silica-coated superparamagnetic iron oxide nanoparticles in glial cellsPublication . Costa, Carla; Brandão, F.; Bessa, M.J.; Costa, S.; Valdiglesias, V.; Kiliç, G.; Fernández-Bertólez, N.; Pásaro, E.; Laffon, B.; Teixeira, João PauloNanotechnology industry is progressing with prospects of substantial benefits to economics and science. Superparamagnetic iron oxide nanoparticles (ION) have been showing excellent magnetic properties, biocompatibility and biodegradability, broadening their potential applications and importance in the biomedical field
- Is organic farming safer to farmers' health? A comparison between organic and traditional farmingPublication . Costa, C.; García-Lestón, J.; Costa, S.; Coelho, P.; Silva, S.; Pingarilho, M.; Valdiglesias, V.; Mattei, F.; Dall'Armi, V.; Bonassi, S.; Laffon, B.; Snawder, J.; Teixeira, João PauloExposure to pesticides is a major public health concern, because of the widespread distribution of these compounds and their possible long term effects. Recently, organic farming has been introduced as a consumer and environmental friendly agricultural system, although little is known about the effects on workers' health. The aim of this work was to evaluate genetic damage and immunological alterations in workers of both traditional and organic farming. Eighty-five farmers exposed to several pesticides, thirty-six organic farmers and sixty-one controls took part in the study. Biomarkers of exposure (pyrethroids, organophosphates, carbamates, and thioethers in urine and butyrylcholinesterase activity in plasma), early effect (micronuclei in lymphocytes and reticulocytes, T-cell receptor mutation assay, chromosomal aberrations, comet assay and lymphocytes subpopulations) and susceptibility (genetic polymorphisms related to metabolism - EPHX1, GSTM1, GSTT1 and GSTP1 - and DNA repair-XRCC1 and XRCC2) were evaluated. When compared to controls and organic farmers, pesticide farmers presented a significant increase of micronuclei in lymphocytes (frequency ratio, FR=2.80) and reticulocytes (FR=1.89), chromosomal aberrations (FR=2.19), DNA damage assessed by comet assay (mean ratio, MR=1.71), and a significant decrease in the proportion of B lymphocytes (MR=0.88). Results were not consistent for organic farmers when compared to controls, with a 48% increase of micronuclei in lumphocytes frequency (p=0.016) contrasted by the significant decreases of TCR-Mf (p=0.001) and %T (p=0.001). Our data confirm the increased presence of DNA damage in farmers exposed to pesticides, and show as exposure conditions may influence observed effects. These results must be interpreted with caution due to the small size of the sample and the unbalanced distribution of individuals in the three study groups.
- Neuronal cytotoxicity and genotoxicity induced by zinc oxide nanoparticlesPublication . Valdiglesias, V.; Costa, C.; Kiliç, G.; Costa, S.; Pásaro, E.; Laffon, B.; Teixeira, João PauloZinc oxide nanoparticles (ZnO NPs) are one of the most abundantly used nanomaterials in consumer products and biomedical applications. As a result, human exposure to these NPs is highly frequent and they have become an issue of concern to public health. Although toxicity of ZnO NPs has been extensively studied and they have been shown to affect many different cell types and animal systems, there is a significant lack of toxicological data for ZnO NPs on the nervous system, especially for human neuronal cells and tissues. In this study, the cytotoxic and genotoxic effects of ZnO NPs on human SHSY5Y neuronal cells were investigated under different exposure conditions. Results obtained by flow cytometry showed that ZnO NPs do not enter the neuronal cells, but their presence in the medium induced cytotoxicity, including viability decrease, apoptosis and cell cycle alterations, and genotoxicity, including micronuclei production, H2AX phosphorylation and DNA damage, both primary and oxidative, on human neuronal cells in a dose- and time-dependent manner. Free Zn(2+) ions released from the ZnO NPs were not responsible for the viability decrease, but their role on other types of cell damage cannot be ruled out. The results obtained in this work contribute to increase the knowledge on the genotoxic and cytotoxic potential of ZnO NPs in general, and specifically on human neuronal cells, but further investigations are required to understand the action mechanism underlying the cytotoxic and genotoxic effects observed.
- Oxidative stress induced by silica-coated iron oxide nanoparticles in SHSY5Y neuronal cellsPublication . Kiliç, G.; Costa, C.; Fernández-Bertólez, N.; Costa, S.; Teixeira, Joao Paulo; Pásaro, E.; Laffon, B.; Vdz Park, M.; Valdiglesias, V.Nanotechnology industry is progressing with prospects of substantial benefits to economics and science. Superparamagnetic iron oxide nanoparticles (ION) have been showing excellent magnetic properties, biocompatibility and biodegradability, broadening their potential applications and importance in the biomedical field. Nevertheless, there are increasing concerns as to the potential adverse effects on human health and environment and, currently, data on the effects of ION on the human nervous system are controversial.
- Silica-coated iron oxide nanoparticles do not induce DNA double strand breaks or aneugenicity in SHSY5Y neuronal cellsPublication . Sánchez-Flores, M.; Kiliç, G.; Costa, C.; Fernández-Bertólez, N.; Costa, S.; Teixeira, João Paulo; Pásaro, E.; Valdiglesias, V.; Laffon, B.Since increasing biomedical applications, both diagnostic and therapeutic, of ION are being developed, it is crucial to know how they interact with the cellular material and the possible consequences derived for human health.
- Variation of DNA damage levels in peripheral blood mononuclear cells isolated in different laboratoriesPublication . Godschalk, R.W.; Ersson, C.; Stępnik, M.; Ferlińska, M.; Palus, J.; Teixeira, João Paulo; Costa, S.; Jones, G.D.; Higgins, J.A.; Kain, J.; Möller, L.; Forchhammer, L.; Loft, S.; Lorenzo, Y.; Collins, A.R.; van Schooten, F.J.; Laffon, B.; Valdiglesias, V.; Cooke, M.; Mistry, V.; Karbaschi, M.; Phillips, D.H.; Sozeri, O.; Routledge, M.N.; Nelson-Smith, K.; Riso, P.; Porrini, M.; López de Cerain, A.; Azqueta, A.; Matullo, G.; Allione, A.; Møller, P.This study investigated the levels of DNA strand breaks and formamidopyrimidine DNA glycosylase (FPG) sensitive sites, as assessed by the comet assay, in peripheral blood mononuclear cells (PBMC) from healthy women from five different countries in Europe. The laboratory in each country (referred to as 'centre') collected and cryopreserved PBMC samples from three donors, using a standardised cell isolation protocol. The samples were analysed in 13 different laboratories for DNA damage, which is measured by the comet assay. The study aim was to assess variation in DNA damage in PBMC samples that were collected in the same way and processed using the same blood isolation procedure. The inter-laboratory variation was the prominent contributor to the overall variation. The inter-laboratory coefficient of variation decreased for both DNA strand breaks (from 68 to 26%) and FPG sensitive sites (from 57 to 12%) by standardisation of the primary comet assay endpoint with calibration curve samples. The level of DNA strand breaks in the samples from two of the centres (0.56-0.61 lesions/10(6) bp) was significantly higher compared with the other three centres (0.41-0.45 lesions/10(6) bp). In contrast, there was no difference between the levels of FPG sensitive sites in PBMC samples from healthy donors in the different centres (0.41-0.52 lesion/10(6) bp).