Departamento de Ciências da Física, Química e Engenharia
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- Comparison of serum selenium levels in inhabitants from different portuguese regionsPublication . Viegas-Crespo, Ana Maria; Pavão, Maria Leonor; Mira, Maria de Lurdes; Torres, Isabel; Halpern, Manuel Júdice; Nève, JeanSelenium is an essential trace element in human nutrition, which is an integral part of the peroxide destroying enzyme, glutathione peroxidase (I). It also takes part in the constitution of other selenoproteins (2) and seems to play other biological functions, such as an important role in the peripheric deiodination of thyroid hormones (3). Normal selen ium status varies widely from one part of the world to another. This situation, which is the consequence of differences in selenium intake, depends on the selenium content in soils and hence in food, as well as its bioavailability (4). Moreover, d ifferent physiological conditions and also the occurrence of pathological situations are liable to influence the status of the element in human beings. In order to assess the selenium status of Portuguese inhabitants in association with other parameters involved in the antioxidant function, and their relationship with atherosclerotic risk factors, we carried out an extensive epidemiological study conceming populations with different socio-economic profiles and feeding habits. In the present study, serum selenium levels were determined in inhabitants from five populations (two urban, two rural and one piscatorial) located in three different Portuguese regions – Mainland, Madeira Island and Azores Archipelago. The relationship of serum selenium concentration with age and sex was also considered. (Introduction)
- Selenium status and cardiovascular risk factors in populations from different portuguese regionsPublication . Viegas-Crespo, Ana Maria; Pavão, Maria Leonor; Santos, Víctor; Cruz, M. L.; Paulo, O.; Leal, J.; Sarmento, N.; Monteiro, M. L.; Amorim, M. F.Selenium as a cofactor of glutathione peroxidase, which prevents lipid peroxidation in mammals, takes part in the direct protection of endothelial cells against reactive oxiygen species that have been implicated in atherogenesis; moreover, it is involved in the biosynthesis of arachidonic acid derivatives in platelets and in the regulation of lipoprotein cholesterol metabolism in human beings and in animal models. These aspects are relevant enough to conclude that low selenium status may be related to atherosclerosis and, consequently, to the occurrence of cardiovascular diseases. Clinical studies showed a decrease in plasma selenium of patient’s wilh congestive cardiomyopathy and/or myocardial infarction. A significant inverse correlation between plasma selenium and severity of coronary atherosclerosis was also reported in man. However, prospective epldemiological studies on the relationship between selenium and cardiovascular disease are rather controversial. The aim of this work was to compare the selenium status by determining serum levels of this element in inhabitants of two urban and one rural Portuguese regions.The relationship between serum selenium levels and generally accepted cardiovascular risk factors was also an objetive. In this context, serurn selenium and serum lipid parameters (total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides) were evaluated. Age and sex as well as alcohol and tobacco consumption were also considered.
- Serum selenium, copper and zinc concentrations in inhabitants of S. Miguel Island (Azores Archipelago)Publication . Viegas-Crespo, Ana Maria; Pavão, Maria Leonor; Santos, Maria Cristina; Santos, Víctor; Nève, JeanSelenium, copper and zinc are trace elements which, besides having other biological functions, are cofactors of enzymes involved in antioxidant systems. The aim of this study is to report the first data on serum selenium, copper and zinc concentrations in Portuguese subjects (W – Women, n = 149; M, Men, n = 92) living in urban, rural and fishing regions of S. Miguel Island. […].
- Descodificação da metáfora em Limite de IdadePublication . Pavão, Maria Leonor[...]. Fica pois, aqui, uma forma de homenagem simples ao poeta «pinsador», como se disse «paternalmente» chamado por Aurélio Quintanilha, o eminente geneticista português, a quem dedicou "Limite de Idade", e uma justificação, em jeito de apaziguamento dos meus receios, para o trabalho que se segue. [...].
- Selenium status and its relationship with cardiovascular risk factors in two portuguese populations of S. Miguel Island: Azores ArchipelagoPublication . Viegas-Crespo, Ana Maria; Pavão, Maria Leonor; Santos, Maria Cristina; Raposo, Aires; Nève, JeanSeleniurn forms part of the active site of glutathione peroxidase enzymes which preveut lipid peroxidation in mammals and take pah in tlie direct protection of endothelial cells against reactive oxiygen species that have been implicated in atherogenesis; moreover these enzymes are involved in the biosynthesis of arachidonic acid derivatives platelets and in the regulation of lipoprotein cholesterol metabolisrn (1-4). To provide further insight into the possible role of selenium in cardiovascular disease, we investigated the assotiation between selenium status and generally accepted cardiovascular risk factors in two populations living in rural and fishing comrnunities of Rabo de Peixe - S. Miguel Island ofthe Azores Archipelago. (Introduction)
- Selenium, copper and zinc in some azorean populationsPublication . Pavão, Maria Leonor; Santos, Víctor; Costa, Ângelo; Borges, Gil; Santos, Maria Cristina; Nève, Jean; Viegas-Crespo, Ana MariaThe overall protection of cells from oxida tive damage dueto reactive oxygen species is mediated by enzymatic and non-enzymatic systems. Selenium, copper and zinc are essential trace elements with major roles, since they are related to Se-dependent glutathione peroxidase enymes and to Cu, Zn-containing superoxide dismutase. Epidemiological studies have been.carried out in recent years to investigate the association between some blood parameters implicated in the antioxidant function and health conditions. The influence of various factors like age, gender, diet, medical treatment and lifestyle has been considered, especially in residents of particular geographic areas. The aim of this work is to present data on serum selenium, copper and zinc concentrations in five populations with different socioeconomic and dietary habits living on the island of S. Miguel (Azores Archipelago, Portugal). (Introduction)
- Dietary selenium intake and antioxidant defenses in tissues of peripuberal ratsPublication . Santos, Maria Cristina; Nève, Jean; Pavão, Maria Leonor; Viegas-Crespo, Ana MariaFree radicais are highly reactive chemical species that can oxidize and damage essential biological molecules. Their formation is a result of endogenous metabolism or of xenobiotics bio-transformation, but under normal physiological conditions cells are protected against oxidative challenge by enzymatic and non enzymatic antioxidants (Sies and Groot, 1992; Yu, 1994). Selenium (Se) is a trace element which essentiality for animais and humans is now well established. The element performs its functions mainly through selenoproteins and several glutathione peroxidases that degrade hydroperoxides using glutathione (GSH) as a reducer, are selenoenzymes playing an important role as antioxidant defenses (Ursini, Maiorino and Gregolin, 1985; Flohé, 1989). However, selenium is also a toxic agent with a narrow range of suitable levels. The main objective of this study was to assess the physiological development of some antioxidant parameters in liver and testes of rats during the puberty until the adult hood and to know if a low selenium supplementation in the diet can have some effect on those parameters, especially on those related with glutathione metabolism. (Introduction)
- Trace element status (Se, Cu, Zn) and serum lipid profile in portuguese subjects of San Miguel Island from Azores' ArchipelagoPublication . Viegas-Crespo, Ana Maria; Pavão, Maria Leonor; Paulo, O.; Santos, Víctor; Santos, Maria CristinaData on selenium, copper and zinc in serum of Portuguese inhabitants of the city of Ponta Delgada - Azores Archipelago are reported for the first time. The subjects are of both sexes, aged 20 to 60 years, and non-abusers of alcohol, tobacco or drugs. Serum concentrations of these elements are in the same range than those found for populations of Lisbon and of some other European countries. Differences between sexes are observed, with serum selenium and zinc levels being higher in males than in females, and the copper levels being higher in females as compared to males. These results can be explained by the hormonal status and/or oral contraceptive steroids intake, particularly for copper. Concerning lipid profile, the majority of individuals have serum lipid parameters within the normal range. In addition, no difference in trace element levels between normo and hyperlipidemic individuals is observed and no conclusive results about the relationship of all evaluated parameters to alcohol, tobacco and drug consumption are observed, in agreement with data obtained in the population of Lisbon.
- Blood antioxidant parameters in subjects from Azorean populations with different sociocultural profilePublication . Pavão, Maria Leonor; António, Sílvia; Figueiredo, Teresa; Santos, Maria Cristina; Nève, Jean; Viegas-Crespo, Ana MariaAge, sex, physiological and pathological conditions, as well as geographical location reflected in diet, social and environmental conditions and even in life habits are relevant factors in the assessment of the prooxidant/antioxidant status of individuais. The aim of this work is to compare some antioxidant parameters, such as whole blood Se-glutathione peroxidase (GSH-Px) and erythrocyte Cu, Zn-superoxide dismutase (SOD) activities, serum selenium, copper and zinc leveis in healthy subjects from three populations with different sociocultural characteristics. Volunteer men and women aged 20-60 were selected from Ponta Delgada (urban population), Ribeira Quente (fishing population) and Água Retorta (rural population) located in the island o f S. Miguel (Azores’ Archipelago, Portugal). No significant differences in GSH-Px activity were found in interpopulation analysis, but the activity tended to be higher in women than in men; in turn, selenium levels, which were maximum in subjects from Ribeira Quente, were significantly bigher in male than in female groups, except in the rural population where they were similar. SOD activities, as well as zinc leveis were significantly higher in both men and women from the fishing population than in the others, where they did not differ. Also SOD, but not zinc or copper, was higher by 13% in women than in men from Ribeira Quente. The rural population exhibited the highest copper concentrations, being much higher in these women than in those from Ribeira Quente or Ponta Delgada. Diet, either food or drinking water might be a major cause for the differences observed.
- Interaction between glutathione and protopine alkaloidPublication . Barreto, Maria do Carmo; Arrabaça, João Daniel; Pavão, Maria Leonor; Pinto, Ruy EugénioIn previous s.rudies, glutathione decreased the inhibition of mitochondrial NADH dehydrogenase by protopine alkaloid. This fact suggests the possibility of fonnation of a complex between glutathione and protopine, decreasing the effectivc concentration of inhibitor in the reaction medium. Absorption spectra of glutathione in the absence and in the presence o f protopine corroborare this hypothesis. Changes in the UV spectrum of glutathione in the prescnce of protopine were detected, and the rate of change with time was monitored.