Browsing by Author "Silva, Maria"
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- Análise citogenética num grupo de doentes com Síndrome Mielodisplásico (estudo retrospetivo)Publication . Silva, Maria; Ambrósio, Ana; Silva, Neuza; Ventura, Catarina; Furtado, José; Correia, HildebertoOs Síndromes Mileodisplásicos (SMD) constituem um grupo de patologias clonais heterogéneas, caraterizadas por citopénias; displasia de uma ou mais linhas celulares mieloides e uma hematopoiese ineficaz. A idade média dos pacientes ao diagnóstico é de 70 anos, com uma predominância de ocorrência do sexo masculino e incidência anual de 3-5/100 000 indivíduos. O objetivo deste estudo é realizar uma avaliação retrospetiva dos resultados citogenéticos obtidos em 440 amostras de medula óssea de pacientes com diagnóstico inicial de SMD e tentar obter uma correlação entre os achados citogenéticos e a patologia em estudo. A população estudada por citogenética convencional é constituída por 218 indivíduos do sexo feminino e 222 indivíduos do sexo masculino, com uma idade média de 66 anos. Das 440 amostras analisadas, 104 (23,6% da população total) apresentavam cariotipos anormais. Os cariotipos que apresentavam anomalias foram divididos em: − População A - Cariotipos com uma só anomalia cromossómica (72 amostras) − População B - Cariotipos com duas anomalias cromossómicas (9 amostras) − População C - Cariotipos complexos com três ou mais anomalias cromossómicas (23 amostras) Na população A, a anomalia observada com maior frequência foi a trissomia 8 (25%), seguida da deleção do cromossoma 5 (16,7%), perda do cromossoma Y (15,3%) e deleção do cromossoma 20 (8,3%), estes resultados não se encontram de acordo com os descritos na literatura. Contudo quando se juntam as três populações, verifica-se que a anomalia observada com maior frequência é a deleção do cromossoma 5 (28,8%) o que já se encontra de acordo com o descrito. A perda do cromossoma Y observada nos indivíduos do sexo masculino, não parece estar correlacionada apenas com a idade, mas parece ser um dos fatores que carateriza este grupo de patologias. As anomalias observadas por análise citogenética convencional (uma técnica de baixo custo) permitiram ao clínico uma melhor avaliação de prognóstico e uma decisão terapêutica mais adequada.
- O ensaio do cometa e o ensaio do micronúcleoPublication . Louro, Henriqueta; Silva, MariaEsquemas-síntese das metodologias utilizadas no Ensaio do Cometa e do Micronúcleo no contexto da Toxicologia Genética.
- Evaluation of combined cytotoxic effects of effects of ochratoxin A and fumonisina B1 in human liver and renal cellsPublication . Tavares, A.M.; Mendonça, I.; Alvito, Paula; Loureiro, S.; Louro, Henriqueta; Silva, MariaMycotoxins are fungal food contaminants with potential to cause severe acute and chronic conditions1. Therefore, food contamination with mycotoxins such as ochratoxin A (OTA) and fumonisin B1 (FB1) causes great concern. Previous studies addressed the co-occurrence of these toxins in foods2, however there is little knowledge on their combined cytotoxic effects. In the present study we aimed to evaluate the cytotoxic effects of mixtures of OTA and FB1 in two human-derived cell lines.
- Exploring the potential interference of estuarine sediment contaminants with the DNA repair capacity of human hepatoma cellsPublication . Pinto, Miguel; Louro, Henriqueta; Costa, Pedro; Caeiro, Sandra; Silva, MariaEstuaries may be reservoirs of a wide variety of pollutants, including mutagenic and carcinogenic substances that may impact on the ecosystem and human health. A previous study showed that exposure of human hepatoma (HepG2) cells to extracts from sediment samples collected in two areas (urban/industrial and riverine/agricultural) of an impacted estuary (Sado, Portugal), produced differential cytotoxic and genotoxic effects. Those effects were found to be consistent with levels and nature of sediment contamination. The present study aimed at evaluating whether the mixtures of contaminants contained in those extracts were able to modulate DNA repair capacity of HepG2 cells. The residual level of DNA damage was measured by the comet assay in cells exposed for 24 or 48 h to different extracts,after a short preexposure to a challenging concentration range of ethyl methanesulfonate(EMS), as a model alkylating agent. The results suggested that the mixture of contaminants present in the tested samples, besides a potential direct effect on the DNA molecule, may also interfere with DNA repair mechanisms in HepG2 cells, thus impairing their ability to deal with genotoxic stress and, possibly, facilitating accumulation of mutations. Humans are environmentally/occupationally exposed to mixtures rather than to single chemicals. Thus, the observation that estuarine contaminants induce direct and indirect DNA strand breakage in human cells, the latter through the impairment of DNA repair, raises additional concerns regarding potential hazards from exposure and the need to further explore these endpoints in the context of environmental risk assessment.
- Human biomonitoring of mycotoxins under HBM4EU: update on key outputsPublication . Alvito, Paula; Assunção, Ricardo; Bajard, Lola; Mol, Hans; Martins, Carla; Mengelers, Marcel; Namorado, Sónia; Vasco, Elsa; Van den Brand, Annick; Viegas, Susana; Silva, MariaThe European Human Biomonitoring Initiative (HBM4EU) is a project gathering 30 countries, funded under Horizon 2020 and running from 2017 until 2021. The goal of HBM4EU is to generate evidence on the current exposure of European citizens to chemicals and on their possible health effects to assess the associated risks. Following a systematic prioritization exercise, the mycotoxins Deoxynivalenol (DON) and Fumonisin B1 (FB1) were considered as priority substances around which the HBM4EU research programme was developed. As part of the HBM4EU project, several policy questions are being addressed for these mycotoxins, concerning analytical methods, exposure levels and high exposure population groups in Europe (including workers), associated time trends, risk characterization, exposure models and toxicokinetic data, human biomonitoring guidance values, key events that determine the health effects of the target mycotoxins, effect biomarkers, data gaps and research needs. Key outputs from HBM4EU achieved until now for DON and FB1, include: i) a biomarker selected to assess human exposure to DON (total urinary DON) that will be used in the aligned studies, ii) several European laboratories selected to perform DON analysis after passing an interlaboratory study, ii) a research protocol on human exposure and geographic variations in Europe, iv) a risk assessment plan to assess DON and FB1 exposure in Europe, v) a review of available toxicokinetics models, vi) a draft on the possible mechanisms of FB1-induced adverse health effects and vii) a specific effect biomarker for FB1.