Browsing by Author "Oliveira, P.A."
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- An Antisense Oligonucletide based therapy for a rare disease: in vitro and in vivo studiesPublication . Gonçalves, M.; Matos, L.; Santos, J.I.; Coutinho, M.F.; Prata, M.J.; Pires, M.J.; Oliveira, P.A.; Alves, SandraMucolipidosis type II (ML II) is a Lysosomal Storage Disorder caused by the deficiency of the enzyme GlcNAc-1-phosphotransferase. This enzyme is responsible for the addition of the mannose-6-phosphate marker to lysosomal enzymes allowing their targeting to lysosomes. From the several ML II mutations, the deletion of two nucleotides from GNPTAB exon 19 (c.3503_3504del) is the most frequent, making it a good target for a mutation specific therapy. In this study, we explored an innovative therapeutic strategy based on the use of antisense oligonucleotides (ASOs) for ML II. In a previous study1 on fibroblasts from ML II patients, ASOs were used to skip exon 19 of the GNPTAB pre-mRNA, successfully resulting in the production of an in-frame mRNA. Currently, our objective is to evaluate the therapeutic potential of this approach, both in vitro in C57BL/6 fibroblasts and in vivo in C57BL/6 mice.
- Effects of titanium dioxide nanoparticles in human gastric epithelial cells in vitroPublication . Botelho, M.C.; Costa, C.; Silva, S.; Costa, S.; Dhawan, A.; Oliveira, P.A.; Teixeira, João PauloManufacturing or using nanomaterials may result in exposure of workers to nanoparticles. Potential routes of exposure include skin, lung and gastrointestinal tract. The lack of health-based standards for nanomaterials combined with their increasing use in many different workplaces and products emphasize the need for a reliable temporary risk assessment tool. Therefore, the aim of this work was to explore the effects of different doses of titanium dioxide nanoparticles on human gastric epithelial cells in vitro. We analyzed proliferation by MTT assay, apoptosis by Tunel, migration by injury assay, oxidative stress by determining GSH/GSSG ratio and DNA damage by Comet assay on nanoparticle-treated AGS human gastric epithelial cell line in comparison to controls. We show and discuss the tumor-like phenotypes of nanoparticles-exposed AGS cells in vitro, as increased proliferation and decreased apoptosis. Our results demonstrate for the first time that nanoparticles induce tumor-like phenotypes in human gastric epithelial cells.
- Effects of Trihalomethanes on Liver MitochondriaPublication . Faustino-Rocha, A.I.; Rodrigues, D.; Gil da Costa, R.M.; Dinis, C.; Talhada, D.; Aragão, S.; Botelho, M.; Colaço, A; Pires, M.J.; Oliveira, M.M.; Peixoto, F; Oliveira, P.A.Introduction: Trihalomethanes (THMs), namely dibromochloromethane (DBCM) and bromodichloromethane (BDCM), are disinfection byproducts of chlorinated water. This experiment aimed to evaluate the mitochondrial dysfunction induced by THMs at low levels in a mouse model.
- Trihalomethanes in liver pathology: Mitochondrial dysfunction and oxidative stress in the mousePublication . Faustino-Rocha, A.I.; Rodrigues, D.; da Costa, R.G.; Diniz, C.; Aragão, S.; Talhada, D.; Botelho, M.; Colaço, A.; Pires, M.J.; Peixoto, F.; Oliveira, P.A.Trihalomethanes (THMs) are disinfection byproducts found in chlorinated water, and are associated with several different kinds of cancer in human populations and experimental animal models. Metabolism of THMs proceeds through enzymes such as GSTT1 and CYP2E1 and gives rise to reactive intermediates, which form the basis for their toxic activities. The aim of this study was to assess the mitochondrial dysfunction caused by THMs at low levels, and the resulting hepatic histological and biochemical changes in the mouse. Male ICR mice were administered with two THMs: dibromochloromethane (DBCM) and bromodichloromethane (BDCM); once daily, by gavage, to a total of four administrations. Animals were sacrificed four weeks after DBCM and BDCM administrations. Blood biochemistry was performed for alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TB), albumin (Alb), total protein (TP), creatinine, and urea. Animals exposed to DBCM and BDCM showed elevated ALT and TB levels (p < 0.05) as compared with controls. Histological analysis confirmed the presence of vacuolar degenerescence and a multifocal necrotizing hepatitis in 33% of animals (n = 2). Mitochondrial analysis showed that THMs reduced mitochondrial bioenergetic activity (succinate dehydrogenase (SQR), cytochrome c oxidase (COX), and ATP synthase) and increased oxidative stress (glutathione S-transferase (GST)) in hepatic tissues (p < 0.05). These results add detail to the current understanding of the mechanisms underlying THM-induced toxicity, supporting the role of mitochondrial dysfunction and oxidative stress in liver toxicity caused by DBCM and BDCM. © 2015 Wiley Periodicals, Inc. Environ Toxicol, 2015.