Browsing by Issue Date, starting with "2011"
Now showing 1 - 10 of 542
Results Per Page
Sort Options
- Bioaccessibility of Hg, Cd and As in cooked black scabbard fish and edible crabPublication . Maulvault, Ana Luísa; Machado, Raquel; Afonso, Cláudia; Lourenço, Helena Maria; Nunes, Maria Leonor; Coelho, Inês; Langerholc, Tomaz; Marques, AntónioRegular consumption of seafood has been widely recommended by authorities. Yet, some species accumulate high levels of contaminants like Hg, Cd and As. In addition, the risks associated to the consumption of such seafood may increase if consumers use cooking practices that enhance the concentration of contaminants and their bioaccessibility. In this study, the bioaccessibility of Hg, Cd and As was assessed with in vitro human digestion of raw and cooked black scabbard fish (Hg; steamed, fried and grilled) and edible crab (Cd and As; steamed and boiled) tissues. Additionally, the toxicological hazards associated with the consumption of these products were also discussed. Generally, Hg, Cd and As bioacessibility increased throughout the digestion process. Cadmium and As revealed high bioaccessibility rates in raw and cooked samples (up to 100%), whereas lower bioaccessible fractions of Hg was observed (up to 40%). Furthermore, this study pointed out the importance of food matrix, elemental chemical properties and cooking practices in the bioaccessibility of Hg, Cd and As. The toxicological hazards revealed that edible crab brown meat (Cd) and grilled black scabbard fish (MeHg) consumption in children should be moderated. In contrast, edible crab muscle (Cd) and fried or steamed black scabbard fish (MeHg) should be consumed to minimize exposure. The use of bioaccessible contaminant data strongly reduced the toxicological risks of MeHg, whereas less risk reduction occurred with Cd and inorganic As.
- Characterization of cytotoxicity and genotoxicity of sediments from a potentially contaminated estuaryPublication . Pinto, Miguel; Dias, Deodália Maria Antunes; Silva, Maria JoãoThe Sado Estuary (W Portugal) is affected by various sources of pollution, associated with the existence of an urban center, heavy-industry, mining activities and agriculture. It also remains a privileged site for fishing activities that are responsible for the supplying of consumable resources either locally or externally. Previous studies revealed sizable amounts of contaminants in the estuary sediments, namely metals, pesticides and polycyclic aromatic hydrocarbons. These compounds can be absorbed and accumulated in the edible parts of estuarine species and in local agricultural products, thus entering the human food chain and posing a public health problem. This study aims to assess the cytotoxic and genotoxic effects of sediments from the Sado Estuary in a human cell line, in order to contribute to hazard identification. Sediments were collected in 4 distinct fishing sites (P, E, A, C) of the Sado Estuary; a reference (Mf) and a potentially contaminated sample (M) from a different estuary (Mira Estuary, W Portugal) were also included. Total organic and inorganic contaminants were extracted with a mixture of methanol:dicholomethane and recovered in DMSO. HepG2 cells were exposed for 48h to several concentrations of each extract. Cytotoxicity was measured by the neutral red assay and genotoxicity by the comet assay. A dose-related decrease in cell viability was observed for extracts P, E and M, indicating sediment contaminant-driven cytotoxicity, whereas no significant cytotoxicity was observed for extracts A, C and Mf. A significant increase in the level of DNA damage was observed following cells exposure to extracts P, E, A and M. Also, increased genotoxicity was observed following treatment with the endonuclease FPG, suggesting the induction of oxidative DNA damage. No significant genotoxicity was induced by extracts C and Mf. The differential cytotoxicity and genotoxicity observed in samples from the northern and southern areas of the Sado Estuary probably reflects the pollution from heavy-industrial and urban area vs. intense agricultural area, respectively. Thus, the data suggest the existence of an inherent environmental, ecological and human health, risk associated with the Sado Estuary sediment contamination that must be further assessed.
- Signaling Pathways of Proteostasis Network Unraveled by Proteomic Approaches on the Understanding of Misfolded Protein RescuePublication . Gomes-Alves, Patricia; Neves, Sofia; Penque, DeborahAttempts to promote normal processing and function of F508del-CFTR, the most common mutant in cystic fibrosis (CF), have been described as potential therapeutic strategies in the management of this disease. Here we described the proteomic approaches, namely two-dimensional electrophoresis (2DE), mass spectrometry (MS), and bioinformatics tools used in our recent studies to gain insight into the proteins potentially involved in lowtemperature or mutagenic treatment-induced rescue process of F508del-CFTR. The proteins identified are part of the proteostasis network, such as the unfolded protein response (UPR) signaling pathways that may regulate the processing of CF transmembrane conductance regulator (CFTR) through the folding and trafficking progression. The complete characterization of these signaling pathways and their regulators in CF will certainly contribute to the development of novel therapeutic strategies against CF.
- Salmonella e os ovos um perigo real?Publication . Correia, Cristina; Santos, Maria Isabel; Assunção, RicardoPerigo Salmonella associado ao consumo de ovos
- EzrA contributes to the regulation of cell size in Staphylococcus aureusPublication . Jorge, A.M.; Hoiczyk, E.; Gomes, João Paulo; Pinho, M.G.EzrA is a negative regulator of FtsZ in Bacillus subtilis, involved in the coordination between cell growth and cell division and in the control of the cell elongation-division cycle. We have now studied the role of the Staphylococcus aureus homologue of the B. subtilis EzrA protein and shown that it is not essential for cell viability. EzrA conditional and null mutants have an overall increase of the average cell size, compared to wild type strains. In the larger ezrA mutant S. aureus cells, cell division protein FtsZ and the cell wall synthesizing Penicillin Binding Proteins (PBPs) are not properly localized. This suggests that there may be a maximum cell diameter that allows formation of a Z-ring capable of recruiting the other components of the divisome and of driving cytokinesis. We propose that the major role of EzrA in S. aureus is in cell size homeostasis.
- Comparison of fungal contamination between hospitals and companies food unitsPublication . Viegas, C.; Ramos, C.; Almeida, M.; Sabino, R.; Verissimo, C.; Rosado, L.A descriptive study was developed to compare air and surfaces fungal contamination in ten hospitals’ food units and two food units from companies. Fifty air samples of 250 litres through impaction method were collected from hospitals’ food units and 41 swab samples from surfaces were also collected, using a 10 by 10 cm square stencil. Regarding the two companies, ten air samples and eight surface samples were collected. Air and surface samples were collected in food storage facilities, kitchen, food plating and canteen. Outdoor air was also collected since this is the place regarded as a reference. Simultaneously, temperature, relative humidity and meal numbers were registered. Concerning air from hospitals’ food units, 32 fungal species were identified, being the two most commonly isolated genera Penicillium sp.
- Selenium Content of Raw and Cooked Marine SpeciesPublication . Martins, Carla; Almeida, Cristina; Alvito, PaulaThe present study evaluates the effects of different cooking methods (grilling, frying and boiling) on selenium contents of six marine species commonly consumed in Portugal. Forty-two composite samples of sardine, horse mackerel, gilthead seabream, silver scabbardfish, hake and octopuswere digested in a microwave systemand analysed by electrothermal atomic absorption spectrometry. The described method is adequate for the analysis of selenium in marine species and meets the requirements of validation and quality control. Mean selenium contents in raw species ranged from 0.35 mg kg−1 to 1.24 mg kg−1. Cooked samples presented mean selenium contents from 0.38 mg kg−1 to 1.85 mg kg−1 in grilled fish, from 1.22 mg kg−1 to 1.28 mg kg−1 in fried fish and from 0.84 mg kg−1 to 0.87 mg kg−1 in boiled fish. No statistically significant differences were determined for selenium levels in raw and cooked samples and in different marine species. Estimated selenium intake agrees well with recommendations and is far below the Upper Tolerable Nutrient Level. This is the first study concerning the evaluation of the effects of cooking methods on selenium contents of marine species consumed in Portugal.
- Molecular investigation of pediatric portuguese patients with sensorineural hearing lossPublication . Nogueira, C.; Coutinho, M.; Pereira, C.; Tessa, A.; Santorelli, F.M.; Vilarinho, L.The understanding of the molecular genetics in sensorineural hearing loss (SNHL) has advanced rapidly during the last decade, but the molecular etiology of hearing impairment in the Portuguese population has not been investigated thoroughly. To provide appropriate genetic testing and counseling to families, we analyzed the whole mitochondrial genome in 95 unrelated children with SNHL (53 nonsyndromic and 42 syndromic) and searched for variations in two frequent genes, GJB2 and GJB6, in the non- syndromic patients. Mutations in mtDNA were detected in 4.2% of the cases, including a hitherto undescribed change in the mtDNA-tRNATrp gene (namely, m.5558A>G). We also identified mono- or biallelic GJB2 mutations in 20 of 53 non-syndromic cases and also detected two novel mutations (p.P70R and p.R127QfsX84). Our data further reinforce the notion that genetic heterogeneity is paramount in children with SNHL.
- Caracterização molecular do gene TPO em crianças Portuguesas com hipotiroidismo congénito causado por disormonogénesePublication . Nogueira, Célia; Vaz Osório, Rui; Santos, Rosário; Jorge, PaulaCongenital hypothyroidism (CH) affects about 1:4000 infants and is considered one of the main causes of preventable mental retardation in children. Universal screening of CH performed through the Portuguese National Neonatal Screening Programme, implemented in Portugal in 1985, has resulted in normal development of attained children. Birth defects of the thyroid can be divided into several groups that represent either changes in the development of the gland or the consequences observed in the deficient synthesis of thyroid hormones. The defects of hormone synthesis caused by dyshor - monogenesis occur in only 10% to 15% of cases of HC. Defects in the thyroid peroxidase (TPO) gene are reported to be one of the most frequent causes of CH due to dyshormonogenesis. The aim is to review the mutational spectrum of the TPO gene in the portuguese population through the molecular investigation of 69 patients with permanent CH due to dys - hormonogenesis. To complement previous results, published in 2005, this work describes the molecular characterization of a further fourteen children with CH and the methodology applied. Extensive in-silico analysis was carried out for the newly identified sequence changes as well as the formerly published putative splicing variant. The sequence variations identified in the TPO gene comprise ten distinct mutations and 29 polymorphisms, enabling the determination of the molecular etiology of CH in fifteen patients. In conclusion, it was possible to obtain a differential diagnosis in twelve fami - lies with CH, using a non-invasive procedure and without interruption of medication. Identification of these and other mutations in the TPO gene can therefore contribute considerably towards diagnosis, a precise genetic counselling, adequate monitoring in future pregnancies as well as putative personalized therapies.
- Prenatal diagnosis in severe cases: a new gain in Portuguese neonatalPublication . Sousa, Carmen; Nogueira, Célia; Fonseca, Helena; Marcão, Ana; Rocha, Hugo; Lopes, Lurdes; Leão, Elisa; Garcia, Juliette; Couceiro, Ana Bela; Vilarinho, LauraIntroduction The expansion of the Portuguese neonatal screening since 2004, based on MS/MS technology, allows the tracing of 25 diseases in all Portuguese newborns in one single laboratory. Following this expansion, the molecular study was also implemented for most diseases, thus allowing confirmation and prenatal diagnosis in severe cases. Methods Five prenatal diagnoses were made in pregnant women who had children affected with severe forms of CPT2 deficiency, ARG1 deficiency, MAD deficiency and LCHAD deficiency. Disease-causing mutations were previously identified in the index patients. Genomic DNA was isolated from whole blood, cultured amniotic fluid cells or chorionic villous tissue by standard methods. Mutations were detected through direct sequencing of PCR products, performed on an automatic sequencer. Results Three prenatal diagnoses were performed on mothers with affected children, found through neonatal screening: CPT2D, MADD and LCHADD. Two other prenatal diagnoses for ARG1D were requested from Italy and France Centers. Results revealed two affected fetus and two heterozygous carriers. One of the studies is still in progress. Discussion Molecular prenatal diagnosis for severe forms can establish the diagnosis in the first trimester of pregnancy. Nevertheless, this procedure is conditioned by prior knowledge of responsible mutations in the index cases.