http://hdl.handle.net/10400.18/60 Mon, 20 May 2013 00:24:35 GMT 2013-05-20T00:24:35Z http://hdl.handle.net/10400.18/1407 Title: Assessment of immunotoxicity parameters in individuals occupationally exposed to lead Authors: García-Lestón, Julia; Roma-Torres, Joana; Mayan, Olga; Schroecksnadel, Sebastian; Fuchs, Dietmar; Moreira, Ana; Pásaro, Eduardo; Méndez, Josefina; Teixeira, João Paulo; Laffon, Blanca Abstract: Although adverse health effects produced by lead (Pb) have long been recognized, studies regarding the immunotoxic effects of occupational exposure report conflicting results. In a previous study, alterations in some immunological parameters were noted in 70 Pb-exposed workers. In view of these results, it was of interest to extend this study comprising a larger population and increasing the number of immunological endpoints assessed. Accordingly, in this study the immunotoxic effects of occupational exposure to Pb were assessed by analyzing (1) percentages of lymphocyte subsets (CD3⁺, CD4⁺, CD8⁺, CD19⁺, and CD56⁺/16⁺); (2) concentration of plasma cytokines, namely, interleukin (IL) 2, IL4, IL6, IL10, tumor necrosis factor (TNF) α, and interferon (IFN) γ; and (3) plasma concentrations of neopterin, tryptophan (Trp), and kynurenine (Kyn). In addition, the possible influence of genetic polymorphisms in the vitamin D receptor (VDR) and δ-aminolevulinic acid dehydratase (ALAD) genes on immunotoxicity parameters was studied. Exposed workers showed significant decreases in %CD3⁺, %CD4⁺/%CD8⁺ ratio, IL4, TNFα, IFNγ, and Kyn to Trp ratio (Kyn/Trp), and significant increases in %CD8⁺, IL10, and Trp levels. All these parameters, except Trp, were significantly correlated with exposure biomarkers. No significant influence of genetic polymorphisms was observed. Significant correlation between Kyn/Trp and neopterin concentrations suggests an involvement of indoleamine 2,3-dioxygenase in the Trp metabolic alterations, which may contribute to some of the immune alterations observed. Results obtained suggest that occupational exposure to PB may influence the immune system by impairing several mechanisms, which might ultimately produce deregulation of the immune response and diminish immunosurveillance in exposed individuals. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10400.18/1407 2012-01-01T00:00:00Z http://hdl.handle.net/10400.18/1268 Title: Self-assembled Mannan Nanogel: Cytocompatibility and Cell Localization Authors: Carvalho, Vera; Castanheira, Pedro; Madureira, Pedro; Ferreira, Sílvia A.; Costa, Carla; Teixeira, João P.; Faro, Carlos; Vilanova, Manuel; Gama, Miguel Abstract: Amphiphilic mannan, produced by the Michael addition of hydrophobic 1-hexadecanethiol to vinyl methacrylated mannan, self-assembles in aqueous medium through hydrophobic interactions among alkyl chains. Resultant nanogel is stable, spherical, polydisperse, with 50-140 nm mean hydrodynamic diameter depending on the polymer degree of substitution, and nearly neutral negative surface charge. No cytotoxicity of mannan nanogel is detected up to about 0.4 mg/mL in mouse embryo fibroblast cell line 3T3 and mouse bone marrow-derived macrophages (BMDM) using cell proliferation, lactate dehydrogenase and Live/Dead assays. Comet assay, under the tested conditions, reveals no DNA damage in fibroblasts but possible in BMDM. BMDM internalize the mannan nanogel, which is observed in vesicles in the cytoplasm by confocal laser scanning microscopy. Confocal colocalization image analysis denotes that the entrance and exit of nanogel and FM 4-64 might occur by the same processes - endocytosis and exocytosis - in BMDM. Physicochemical characteristics, in vitro cytocompatibility and uptake of self-assembled mannan nanogel by mouse BMDM are great signals of the potential applicability of this nanosystem for macrophages targeted delivery of vaccines or drugs, acting as potential nanomedicines, always with the key goal of preventing and/or treating diseases. Fri, 08 Jun 2012 00:00:00 GMT http://hdl.handle.net/10400.18/1268 2012-06-08T00:00:00Z http://hdl.handle.net/10400.18/1218 Title: DNA damage and susceptibility assessment in industrial workers exposed to styrene. Authors: Costa, Carla Sofia; Bastos da Costa, Solange Cristina; Pinho e Silva, Susana; Santos Coelho, Patrícia Clara; Botelho, Mónica; Gaspar, Jorge; Rueff, J.; Laffon, Blanca; Teixeira, João Paulo Abstract: Styrene is a widely used chemical in the manufacture of synthetic rubber, resins, polyesters, and plastics. The highest levels of human exposure to styrene occur during the production of reinforced plastic products. The objective of this study was to examine occupational exposure to styrene in a multistage approach, in order to integrate the following endpoints: styrene in workplace air, mandelic and phenylglyoxylic acids (MA + PGA) in urine, sister chromatid exchanges (SCE), micronuclei (MN), DNA damage (comet assay), and genetic polymorphisms of metabolizing enzymes (CYP2E1, EPHX1, GSTM1, GSTT1, and GSTP1). Seventy-five workers from a fiberglass-reinforced plastics factory and 77 unexposed controls took part in the study. The mean air concentration of styrene in the breathing zone of workers (30.4 ppm) and the mean concentration of urinary metabolites (MA + PGA = 443 ± 44 mg/g creatinine) exceeded the threshold limit value (TLV) and the biological exposure index (BEI). Significantly higher SCE frequency rate and DNA damage were observed in exposed workers, but MN frequency was not markedly modified by exposure. With respect to the effect of genetic polymorphisms on different exposure and effect biomarkers studied, an increase in SCE levels with elevated microsomal epoxide hydrolase activity was noted in exposed workers, suggesting a possible exposure-genotype interaction. Thu, 12 Jul 2012 00:00:00 GMT http://hdl.handle.net/10400.18/1218 2012-07-12T00:00:00Z http://hdl.handle.net/10400.18/1217 Title: Genotoxic effects of occupational exposure to lead and influence of polymorphisms in genes involved in lead toxicokinetics and in DNA repair Authors: García-Lestón, Julia; Roma-Torres, Joana; Vilares, Maria; Pinto, Rui; Prista, João; Teixeira, João Paulo; Mayan, Olga; Conde, Joao; Pingarilho, Marte; Gaspar, Jorge Francisco; Pásaro, Eduardo; Méndez, Josefina; Laffon, Blanca Abstract: Lead is still widely used in many industrial processes and is very persistent in the environment. Although toxic effects caused by occupational exposure to lead have been extensively studied, there are still conflicting results regarding its genotoxicity. In a previous pilot study we observed some genotoxic effects in a population of lead exposed workers. Thus, we extended our study analysing a larger population, increasing the number of genotoxicity endpoints, and including a set of 20 genetic polymorphisms related to lead toxicokinetics and DNA repair as susceptibility biomarkers. Our population comprised 148 workers from two Portuguese factories and 107 controls. The parameters analysed were: blood lead levels (BLL) and δ-aminolevulinic acid dehydratase (ALAD) activity as exposure biomarkers, and T-cell receptor (TCR) mutation assay, micronucleus (MN) test, comet assay and OGG1-modified comet assay as genotoxicity biomarkers. Lead exposed workers showed markedly higher BLL and lower ALAD activity than the controls, and significant increases of TCR mutation frequency (TCR-Mf), MN rate and DNA damage. Oxidative damage did not experience any significant alteration in the exposed population. Besides, significant influence was observed for VDR rs1544410 polymorphism on BLL; APE1 rs1130409 and LIG4 rs1805388 polymorphisms on TCR-Mf; MUTYH rs3219489, XRCC4 rs28360135 and LIG4 rs1805388 polymorphisms on comet assay parameter; and OGG1 rs1052133 and XRCC4 rs28360135 polymorphisms on oxidative damage. Our results showed genotoxic effects related to occupational lead exposure to levels under the Portuguese regulation limit of 70 μg/dl. Moreover, a significant influence of polymorphisms in genes involved in DNA repair on genotoxicity biomarkers was observed. Wed, 01 Aug 2012 00:00:00 GMT http://hdl.handle.net/10400.18/1217 2012-08-01T00:00:00Z