Percorrer por autor "Morais, S."
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- In vitro biomineralization by osteoblast-like cells : Part II - characterisation of cellular culture supernatantsPublication . Morais, S.; Carvalho, Graça S. de; Faria, Joaquim; Gomes, Helder; Sousa, JoãoThe quantification of total calcium, phosphorus, iron, chromium and nickel in cell culture medium by electrochemical or spectroscopic means may require digestion of samples. Nevertheless, when pH adjustment is performed for values higher than about 6.5, the formation of two phases occurs: a white precipitate and a clear solution. Analysing both phases using microelectrodes, atomic absorption spectrometry (AAS), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, X-ray dispersive (XRD) analysis, scanning electron microscopy (SEM) and energy dispersive spectroscopic (EDS) analysis, it was observed that iron, chromium and nickel are not co-precipitating with the white solid phase. If quantification of calcium, phosphorus and magnesium is intended, a ten-fold dilution at least, must be performed to avoid most of these elements going into the precipitate. This knowledge is crucial if a mineralization study is going to be made.
- Monitoring of ochratoxin a exposure of the Portuguese population through a nationwide urine survey – Winter 2007Publication . Duarte, S.C.; Bento, J.M.V.; Pena, A.; Lino, C.M.; Delerue-Matos, Cristina; Oliva-Teles, T.; Morais, S.; Correia, Manuela; Oliveira, Beatriz; Alves, M. Rui; Pereira, J.A.Ochratoxin A (OTA) is a mycotoxin produced by a variety of fungi, such as Penicillium verrucosum and Aspergillium spp., which has been found to have a wide number of potentially deadly toxic effects, and can enter the human organism through a variety of means. It then finds its way into the bloodstream and, after a lengthy process, is eventually excreted through the urine. It can thus be detected in its original form not only in blood samples but also in this biological medium. As such, and in an attempt to evaluate the exposure of the Portuguese population to this mycotoxin, morning urine samples were collected during the Winter of 2007, from each of five geographically distinct Portuguese locations — Bragança, Porto, Coimbra, Alentejo, and Algarve — and subjected to extraction by immunoaffinity columns and to OTA quantification through liquid chromatography coupled with fluorescence detection. Prevalent incidence was higher than 95% with Coimbra being the exception (incidence of 73.3%). In nearly all locations, the OTA content of most samples was found to be above the limit of quantification (LOQ) of 0.008 ng/ml. Indeed, excluding Coimbra, with an OTA content level of 0.014 ng/ml, all regions featured content values over 0.021 ng/ml.
- Ochratoxin A contamination of bread – Portugal nationwide survey during winter 2007/2008.Publication . Duarte, S.C.; Bento, J.M.V.; Pena, A.; Lino, C.M.; Pereira, J.A.; Delerue-Matos, Cristina; Oliva-Teles, T.; Morais, S.; Correia, Manuela; Oliveira, BeatrizOchratoxin A (OTA) remains one of the most important mycotoxins known, due to its ubiquitous occurrence, wide range of susceptible food commodities and observed toxic effects, in both animals and humans. The reported toxic effects include carcinogenic, nephrotoxic, teratogenic, neurotoxic and immunotoxic.
- Ochratoxin A content in urine from Bragança and Alentejo: a compartive analysis (Winter 2007).Publication . Duarte, S.C.; Bento, J.M.V.; Pena, A.; Lino, C.M.; Pereira, J.A.; Delerue-Matos, Cristina; Oliva-Teles, T.; Morais, S.; Correia, Manuela; Oliveira, BeatrizOchratoxin A (OTA) is a mycotoxin which possesses a variety of toxic effects, including enzyme inhibition, immunosuppression, teratogenicity, nephrotoxicity, and carcinogenicity. It is produced by fungi for which foodstuffs such as beans, cereals, fruits, and seeds constitute an ideal growing media. It has proven itself at least partly resistant to food processing methods, meaning it is also present in derived products and thus finds its way into the human organism. Recent studies have suggested that, though OTA can be found in both plasma and urine – through which it is eliminated, though with great difficulty – the latter provides a better indication of OTA ingestion. Its collection procedure is also less invasive, and developments in analytical methodology allow an equally precise analysis.