Percorrer por autor "Ferreira, I."
A mostrar 1 - 10 de 10
Resultados por página
Opções de ordenação
- Application of chemometric methods to assess the impact of intensive horticulture practices on groundwater content of nitrates, sodium, potassium and pesticidesPublication . Pinto, E.; Melo, A.; Aguiar, A.; Mansilha, C.; Pinho, O.; Ferreira, I.
- Emerging water contaminantsPublication . Mansilha, C.; Melo, A.; Ferreira, I.; Domingues, V.; Pinho, C.; Rocha, S.; Gameiro, P.
- Genetic and virulence characterization of Toxoplasma gondii strains isolated from pigeons in Lisbon regionPublication . Vilares, Anabela; Gargate, M.J.; Ferreira, I.; Martins, S.; Waap, H.; Ângelo, H.habitat with cats and humans, bands are observed in recreational areas such as urban parks, playgrounds and parks. The interaction between cats, birds and human population is quite evident favoring the fecal-oral transmission of T. gondii between the definitive host and intermediate hosts, in the urban cycle of the parasite. The results of the inoculation in vivo of the brain homogenates showed pigeon isolation rates (58.5%) significantly higher when compared with previous studies, including the preliminary study in 2006 that the isolation rate in mice was 39,1% (9/23) (Waap 2008) and another that was not achieved any isolation in mouse (Godoi 2010). The genotypic analysis revealed a majority of strains of type II, which is consistent with what has been described in Portugal, the rest of Europe and the USA (Ajzenberg 2005, Fazaeli 2000, Honoré 2000, Howe 1997, Waap 2008) . We also isolated strains of type III and type I. The identification of type III strains in animals have been reported by other authors, but the type I have been rarely found in animals has not been previously described in Portugal except in a preliminary study of our team at the 2008 (Waap 2008). The type I strains are usually associated with high virulence in laboratory mice, leading to death within days. This strain was identified by molecular biology and has not been isolated in vivo. The difficulty in isolation of strain may be related to the small number of cysts of the type I strains can develop, these type strains are considered low cystogenic. Genetic characterization of strains of T. gondii is far from its terminus, more sequences of different genes should be studied to help the understanding of the molecular epidemiology and genetic characterization of T. gondii, a relevant parasite for which these data are lacking. The combination of data from humans and animals, through the use of high resolution genetic characterization should improve our perceptive of T. gondii, which will be ultimately beneficial for the control of T. gondii transmission.
- Groundwater from infiltration galleries used for small public water supply systems: contamination with pesticides and endocrine disruptorsPublication . Mansilha, C.; Melo, A.; Ferreira, I.; Pinho, O.; Domingues, V.; Pinho, C.; Gameiro, P.Infiltration galleries are among the oldest known means used for small public water fountains. Owing to its ancestral origin they are usually associated with high quality water. Thirty-one compounds, including pesticides and estrogens from different chemical families, were analysed in waters from infiltration galleries collected in Alto Douro Demarcated Wine region (North of Portugal). A total of twelve compounds were detected in the water samples. Nine of these compounds are described as presenting evidence or potential evidence of interfering with the hormone system of humans and wildlife. Although concentrations of the target analytes were relatively low, many of them below their limit of quantification, four compounds were above quantification limit and two of them even above the legal limit of 0.1 μg/L: dimethoate (30.38 ng/L), folpet (64.35 ng/L), terbuthylazine-desethyl (22.28 to 292.36 ng/L) and terbuthylazine (22.49 to 369.33 ng/L).
- Impact of intensive horticulture practices on groundwater content of nitrates, sodium, potassium, and pesticidesPublication . Melo, A.; Pinto, E.; Aguiar, A.; Mansilha, C.; Pinho, O.; Ferreira, I.A monitoring program of nitrate, nitrite, potassium, sodium, and pesticides was carried out in water samples from an intensive horticulture area in a vulnerable zone from north of Portugal. Eight collecting points were selected and water-analyzed in five sampling campaigns, during 1 year. Chemometric techniques, such as cluster analysis, principal component analysis (PCA), and discriminant analysis, were used in order to understand the impact of intensive horticulture practices on dug and drilled wells groundwater and to study variations in the hydrochemistry of groundwater. PCA performed on pesticide data matrix yielded seven significant PCs explaining 77.67% of the data variance. Although PCA rendered considerable data reduction, it could not clearly group and distinguish the sample types. However, a visible differentiation between the water samples was obtained. Cluster and discriminant analysis grouped the eight collecting points into three clusters of similar characteristics pertaining to water contamination, indicating that it is necessary to improve the use of water, fertilizers, and pesticides. Inorganic fertilizers such as potassium nitrate were suspected to be the most important factors for nitrate contamination since highly significant Pearson correlation (r = 0.691, P < 0.01) was obtained between groundwater nitrate and potassium contents. Water from dug wells is especially prone to contamination from the grower and their closer neighbor's practices. Water from drilled wells is also contaminated from distant practices.
- Isolation and molecular characterization of Toxoplasma gondii isolated from pigeons and stray cats in Lisbon, PortugalPublication . Vilares, A.; Gargaté, M.J.; Ferreira, I.; Martins, S.; Júlio, C.; Waap, H.; Angelo, H.; Gomes, João PauloCats and pigeons are important factors in the epidemiology of Toxoplasma gondii as felidsare the only definitive hosts that can excrete environmentally resistant oocysts, andpigeons share the same places of cats and humans constituting a good model and indicatorof the ground field contamination. We aimed to study the virulence and genotypes ofT. gondii isolated from pigeons and stray cats in Lisbon, Portugal. Fresh samples of brainfrom 41 pigeons and 164 cats revealing antibodies to T. gondii were inoculated in mice.Three isolates (one isolated from a cat and two isolated from pigeons) were virulent in themouse model. Sag2-based genotyping of T. gondii was achieved in 70.7% (29/41) of samplesisolated from pigeons (26 samples were type II, two were type III, and one strain was type I).From the cat brain samples, 50% (82/164) yielded Sag2 positive results, where 72 belongedto genotype II and 10 were no type III (it was not possible to discriminate between typeI and II). Further genotyping was obtained by multiplex PCR of 5 microsatellites (TUB2,TgM-A, W35, B17, B18), allowing the identification of two recombinant strains that hadbeen previously identified as type II by Sag2 amplification (one isolated from cat brain andthe other from pigeon brain). This is the first evidence of recombinant strains circulatingin Portugal and the first report of T. gondii genotyping from cats in this country. This studyalso highlights the importance of environmental contamination in the synanthropic cycleconstituting a potential source of human infection.
- Optimisation of a solid-phase microextraction/HPLC/Diode Array method for multiple pesticide screening in lettucePublication . Melo, A.; Aguiar, A.; Mansilha, C.; Pinho, O.; Ferreira, I.A new method was developed for the determination of 10 pesticides widely used in lettuce production (acetamiprid, azoxystrobin, cyprodinil, fenhexamid, fludioxonil, folpet, iprodione, metalaxyl, pirimicarb, and tolyfluanid) using solid-phase microextraction (SPME) and liquid chromatography (HPLC) with diode-array detection (DAD). The extraction performance of four different SPME coatings, polydimethylsiloxane (PDMS), PDMS/divinylbenzene (PDMS/DVB), carbowax/templated resin (CW/TPR), and polyacrylate (PA) was evaluated using an interface SPME–HPLC. CW/TPR fibre was selected as the most appropriate for the extraction of majority of these pesticides. Three variables (pH, NaCl% and extraction time) were considered key factors in the optimisation process. Interactions between these analytical factors and their optimal levels were investigated by response surface methodology based on central composite design. The method allowed the determination of azoxystrobin, cyprodinil, fenehexamid, fludioxonil, folpet, iprodione, and tolyfluanid in lettuce at concentrations between 0.8 and 25.6 mg/kg, i.e., bellow the maximum residues levels allowed for those compounds in lettuce. Lettuce samples that suffered pesticide treatments with folpet and fenehexamid were analysed during days to harvest to study the dissipation behaviour of the pesticides used. Concentration of folpet was 92.8; 53.4; 22.9; 17.9; 7.45; 1.85 mg/kg and concentration of fenhexamid was 158.1; 76.2; 31.0; 27.3; 7.24; 0.87 mg/kg, respectively for t0, t1, t3, t6, t7, t9 days, and not detected at t14 days for the two pesticides.
- Quantification of endocrine disruptors and pesticides in water using weighted linear regression schemesPublication . Melo, A.; Mansilha, C.; Pinho, O.; Ferreira, I.
- Safety assessment of poly(methylmethacrylate) nanomaterials for drug delivery: genotoxicity in mammalian cellsPublication . Bettencourt, Ana; Graça, DIogo; Matos, A.; Ferreira, I.; Almeida, A.; Gonçalves, L.; Santos, Joana; Louro, Henriqueta; Silva, Maria JoãoThe application of nanomaterials (NMs) as carriers for drug delivery is seen as a key factor in innovative medicine products. A major class of drug controlled release systems includes polymeric NMs, due to their unique physicochemical properties that can be manipulated using well-established techniques. Among these, polymethylmethacrylate (PMMA) is a biomedical polymer with increasing interest as a carrier system of many drugs, e.g. antibiotics, for in situ therapy. However, the same unique properties that render these NMs so valuable may underlie unforeseen toxicological adverse side effects that must be assessed prior to their application. A major concern is their long-term effects, particularly, their potential genotoxicity, given that may persist in the human body. The present work aimed at synthesizing PMMA particles for drug delivery and assessing their safety through in vitro genotoxicity testing. PMMA particles were prepared by double emulsion-solvent-evaporation methodology and the relevant properties concerning their nano-biological interactions namely, size distribution, zeta potential and hydrophobicity were measured. As part of their safety assessment the cytotoxicity (MTT test) and genotoxicity (comet and micronucleus assays) were characterized using murine L929 fibroblasts. The results showed an absence of cytotoxicity and genotoxicity. In fact, neither DNA damage nor oxidative DNA damage was detected by the comet and FPG-modified comet assay, respectively. Furthermore, no clastogenicity/aneugenicity was observed by the micronucleus assay up to 5 mg/mL (OECD-TG 487 guideline). Further studies, including in vivo mutagenicity testing, are desirable for assuring the safe use of this NM.
- Towards a risk assessment for Giardia sp. and Cryptosporidium sp. in Portuguese fluvial beaches: a seasonal sampling over two yearsPublication . Júlio, C.; Ferreira, I.; Martins, S.; Sá, C.; Ângelo, H.; Guerreiro, J.; Tenreiro, R.Abstract background: Waterborne outbreaks of diarrhoeal illness reported worldwide are mostly associated with Cryptosporidium sp. and Giardia sp. Lake and river waters contaminated with (oo)cysts are major routes of human exposure making essential the development of preventive strategies for water safety. Since monitoring of water contamination with (oo)cysts is not routinely performed in Portugal, this study aims to unveil the possible associations between Portuguese fluvial beach characteristics and risk for public health caused by different genotypes of Giardia sp. and Cryptosporidium sp.. Abstract Methods: Nineteen beaches were selected according to land use and environmental parameters and sampled, on winter and summer, for the presence of Giardia sp. and Cryptosporidium sp., as well as faecal indicators and physicochemical parameters. Immunomagnetic separation was performed according the US EPA Method 1623 with Dynal procedure (Dynabeads), followed by detection of (oo)cysts by immunofluorecence microscopy after staining with FICT-labelled monoclonal antibody. Cysts viability was also confirmed by nucleic acid dye (DAPI) staining. Abstract Results: The results show that Giardia cysts are present at least in 83% of the sampled beaches. Presence of Cryptosporidium oocysts was not lower than 74%. Additionally, seasonal differences on (oo)cysts amount were perceived. A dendrogram analysis highlighted different clusters which evidence patterns among the sampled beaches. Principal Component Analysis also indicates distinct weights for land use, physical-chemical and microbiological parameters in these different clusters. Abstract Conclusions: The results of the present study indicate that Giardia sp. and Cryptosporidium sp. are widely distributed and should be considered as a public health issue. Moreover, beach clusters turn out to be a helpful tool to assess the public health risk.