DCFQE - Artigos em Revistas Internacionais / Articles in International Journals
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- 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.
- Comparison of whole blood glutathione peroxidase activity, levels of serum selenium and lipid peroxidation in subjects from the fishing and rural communities of "Rabo de Peixe" Village, San Miguel Island, The Azores Archipelago, Portugal.Publication . Pavão, Maria Leonor; Cordeiro, Carla; Costa, Ângelo; Raposo, José Aires; Santos, Maria Cristina; Nève, Jean; Viegas-Crespo, Ana MariaThe activity of glutathione peroxidase (GSH-Px), serum selenium (Se), and thiobarbituric acid reactive substances (TBARS) were measured in the whole blood of 148 healthy adults aged 20–60 yr from the fishing and rural communities of “Rabo de Peixe,” The Azores, Portugal. The subjects did not live in the same household and had different socioeconomic profiles and dietary habits. The serum lipid profile and selected life habits were also considered in this study. No significant differences in the activity of GSH-Px were found in the interpopulation or intrapopulation analyses, classified by age or lipid profile. An age-dependent GSH-Px increase was noted in the younger male (M) subgroups (20–39 yr). The Se levels were higher in fishers (f) of both genders (M, F) than in subjects living in the rural (r) environment: 110±25 µg/L (f, M), 89±20 µg/L (f, F), 88±22 µg/L (r, M) and 80±17 µg/L (r, F). In the fishers, but not in the rural population, Se was higher in the males, but it did not show significant variation with age. The levels of TBARS were lower in the f than in the r male group. The Se level was lower and TBARS higher in the hyperlipemic women in the f group, compared to the corresponding controls. Our results suggest that the fishers (mainly men) show a better antioxidant status than that of their rural counterparts, due to differences in dietary habits between the study populations and between genders.
- Inhibition of mouse liver respiration by Chelidonium majus isoquinoline alkaloidsPublication . Barreto, Maria do Carmo; Pinto, Ruy Eugénio; Arrabaça, João Daniel; Pavão, Maria LeonorThe alkaloids from Chelidonium majus L. which had a significant inhibitory effect in mitochondrial respiration were those which contain a positive charge due to a quaternary nitrogen atom, i.e., chelerythrine, sanguinarine, berberine and coptisine, both with malate+glutamate or with succinate as substrates. When malate+glutamate was used as substrate, chelerythrine and berberine, which contain methoxy groups, were particularly more active, since they had a strong effect even at low concentrations. In submitochondrial particles, berberine and coptisine had a marked inhibitory effect on NADH dehydrogenase activity but practically no effect on succinate dehydrogenase activity, whereas chelerythrine and sanguinarine inhibited more strongly succinate dehydrogenase than NADH dehydrogenase, which is in agreement with the results found for mitochondrial respiration. Protopine and allocryptopine, which did not inhibit mitochondrial respiration, strongly inhibited NADH dehydrogenase in submitochondrial particles, but had no effect on succinate dehydrogenase activity.
- Diagnosis of Enzyme Inhibition Based on the Degree of InhibitionPublication . Antunes, Fernando; Marinho, Helena Susana; Barreto, Maria do Carmo; Pavão, Maria Leonor; Pinto, Ruy EugénioIn this work, a method for the diagnosis of kinetic inhibition, based on the dependence of the degree of inhibition (s) on the inhibitor concentration [1] and on the substrate concentration [S], is presented. Because the degree of inhibition is a ratio between rates, kinetic data are normalized by the introduction of an internal control-the rate of the uninhibited reaction. Therefore, the error associated with the kinetic measurements decreases and less experimental measurements are necessary to achieve the diagnosis. The process described, which uses graphical and/or non-linear fitting procedures, allows distinguishing between 20 different kinds of inhibition, including not only linear and hyperbolic, but also parabolic and rational 2,2 inhibitions. Rational 2,2 indicates a new type of inhibition corresponding to an incomplete parabolic inhibition, i.e. mechanistically it corresponds to an inhibitor that binds to two inhibition sites producing enzymatic complexes that are still active. In spite of its comprehensiveness, the diagnosis process is greatly facilitated by the division of the diagnosis of the inhibition in a step-by-step procedure, where only two rival models are evaluated in each step. In the non-linear fittings, the choice between rival models uses a test based on information statistics theory, the Akaike information criterion test, in order to penalize complex models that tend to be favoured in fittings. Finally, equations that allow the determination of inhibition kinetic constants were also deduced. The formalism presented was tested by examining inhibition of acid phosphatase by phosphate (a linear competitive inhibitor).
- Trace element status (Se, Cu, Zn) in healthy portuguese subjects of Lisbon population-a reference studyPublication . Lopes, Paula Alexandra; Santos, Maria Cristina; Vicente, Luís; Rodrigues, Maria Olívia; Pavão, Maria Leonor; Nève, Jean; Viegas-Crespo, Ana MariaSerum levels of selenium, copper, and zinc were systematically determined in healthy subjects of the Lisbon population. The sample consisted of 183 blood donors of both genders who were divided into two age groups: 20-44 and 45-70 yr of age; relationships with gender, age, the lipid profile, and tobacco consumption were investigated. In the female group, the intake of oral contraceptives and pregnancy were considered for the youngest women, and hormonal replacement therapy (HRT) was taken into account for the oldest ones. Serum concentrations of these elements were in the same range as those found for populations of other European countries. Differences between genders were observed for the three elements studied, with serum selenium and zinc concentrations higher in men and copper levels higher in women. Age-dependent differences were found for selenium: The oldest subjects (regardless gender) presented the highest concentrations of selenium in serum as further demonstrated by the positive correlation with age. In both pregnant and contraceptive-using women, copper was greatly increased, confirming the influence of estrogen status and/or oral contraceptive intake on increased serum copper levels. However, in postmenopausal women, HRT did not significantly affect serum copper levels. Selenium, copper, and zinc status were not different between normolipidemic and hyperlipidemic subjects for the same gender and age range, but selenium levels tended to increase with hyperlipidemia when considering the whole group of subjects. With respect to the lifestyle, higher serum zinc levels were found in tobacco-consuming men. Albumin serum levels were similar for all considered subgroups, except for the pregnant women, for whom a decrease in this parameter was observed. The present study allowed one to obtain reference values for this healthy group of population, which will serve for a comparative study with groups having pathological conditions, such as cardiovascular disease.
- Systemic markers of the redox balance and Apolipoprotein E Polymorphism in Atherosclerosis: the Relevance for an Integrated StudyPublication . Lopes, Paula Alexandra; Napoleão, Patrícia; Pinheiro, Teresa; Ceia, Fátima; Steghens, Jean-Paul; Pavão, Maria Leonor; Santos, Maria Cristina; Viegas-Crespo, Ana MariaProspective studies have demonstrated that an imbalance between oxidative damage and antioxidative protection can play a role in the development and progression of atherosclerosis. Also, genotypes with the apolipoprotein E ζ4 allele have been associated with an increase risk for this pathology. Based on this knowledge, the aim of this study was to evaluate indicators of the redox balance, trace elements, and apolipoprotein E allelic profile in subjects from the Lisbon population with clinically stable atherosclerosis, at risk for atherosclerotic events, and in healthy subjects for comparison. The activities of superoxide dismutase in erythrocytes and glutathione peroxidase in whole blood, plasma total thiols, and serum ceruloplasmin were kept unchanged among the three groups. Serum α-tocopherol was increased in atherosclerotic patients. Total malondialdehyde in serum and protein carbonyls in plasma, which are indicators of lipid and protein oxidative damage, respectively, reached their highest values in risk subjects. The concentrations of potassium and calcium, in plasma and in blood cells, were slightly elevated in patients and might reflect an electrolytic imbalance. Regarding the apolipoprotein E polymorphism, atherosclerotic patients had an increased incidence of the high-risk genotypes for atherogenesis (ζ3/ζ4 and ζ4/ζ4). A multivariate model applied to the general population using most of the parameters clearly separated the three groups at study (i.e., the healthy group from the steady-state group of risk disease and from the atherosclerotic one). As shown by us, the usefulness of biochemical and complementary genetic markers is warranted for a better knowledge on atherosclerosis molecular basis.
- Whole blood glutathione peroxidase and erythrocyte superoxide dismutase activities, serum trace elements (Se, Cu, Zn) and cardiovascular risk factors in subjects from the city of Ponta Delgada (Island of San Miguel, The Azores' Archipelago, Portugal)Publication . Pavão, Maria Leonor; Figueiredo, Teresa; Santos, Víctor; Lopes, Paula Alexandra; Ferin, Rita; Santos, Maria Cristina; Nève, JeanActivities of whole blood glutathione peroxidase (GSH-Px) and erythrocyte superoxide dismutase (SOD) and serum levels of selenium (Se), copper (Cu) and zinc (Zn) were measured in 118 apparently healthy subjects aged 20–60 years from the city of Ponta Delgada, Island of San Miguel, The Azores Archipelago, Portugal. Data were analysed by age/gender, lipid profile and blood pressure as cardiovascular risk factors searching for their relevance when assessing reference values for antioxidant biomarkers. GSH-Px was in the same range, but SOD was significantly lower than in other Portuguese populations. Neither activity differed with gender. GSH-Px activity increased with age, namely in normolipidemic men versus the hyperlipidemic group in which a decrease was observed. This suggests a progressive impairment of GSH-Px with age caused by an enhanced production of oxidant species in hyperlipidemia. GSH-Px was 30% lower in male hypertensives versus normotensives. SOD activity did not relate to age or blood pressure but was 17% higher in the hyperlipidemic men versus the normolipidemic group, suggesting a better antioxidant protection by SOD than by GSH-Px in hyperlipidemia and hypertension. Se was higher in men versus women, particularly in the older subjects, and partly related to hyperlipidemia. Zn levels showed a similar dependency on gender, not related to age or lipid profile. Cu levels were much higher in women than in men in all age or lipid profile classes and decreased in hyperlipidemia. They were lowered with age in both genders, particularly in normolipidemic women. The present research therefore suggests that hyperlipidemia and hypertension do affect antioxidant status and should be considered when assessing antioxidant biomarkers in blood.
- Polymorphism of the APOE locus in the Azores Islands (Portugal)Publication . Bettencourt, Conceição; Montiel, Rafael; Santos, Cristina; Pavão, Maria Leonor; Viegas-Crespo, Ana Maria; Lopes, Paula Alexandra; Lima, ManuelaOur aim in this study is to report on the polymorphism of the APOE gene in the Azores Islands (Portugal) to obtain a population baseline of the existing variation in this locus, known to be one of the genetic determinants of plasma lipid levels. One hundred twenty-six Azorean individuals were typed for the APOE polymorphism using standard PCR-RFLP. Allele frequencies obtained for APOE*2, APOE*3, and APOE*4 were 6.75%, 83.73%, and 9.52%, respectively. The APOE*3/*3 genotype presented the highest frequency (69.84%), and the APOE*4/*4 genotype had the lowest frequency (0.79%). Genotype frequencies were in conformity with Hardy-Weinberg expectations. The observed genotype and allele frequencies were similar to those reported for other Iberian samples. Furthermore, Nei's gene diversity ((H) over cap = 0.2864 +/- 0.0351) was similar to that reported for samples from mainland Portugal. The data generated from this study will be of importance in the context of ongoing studies concerning the factors that influence lipid levels in the Azorean population.
- Comparison of Apolipoprotein E polymorphism and other atherosclerotic risk factors in two Portuguese populations: the Influence of InsularityPublication . Lopes, Paula Alexandra; Gaspar, Gisela; Napoleão, Patrícia; Santos, Maria Cristina; Pavão, Maria Leonor; Viegas-Crespo, Ana MariaO principal objectivo deste estudo é o de pesquisar o efeito da insularidade nos polimorfismos da apolipoproteína (apo) E em indivíduos saudáveis do continente (Lisboa) e de Ponta Delgada (Ilha de S. Miguel, Arquipélago dos Açores). Adicionalmente, estudar a distribuição dos seus genótipos em doentes com aterosclerose da Ilha de S. Miguel. Em Lisboa, a distribuição dos genótipos da apo E foi a seguinte: e3/e3 > e3/e4 > e2/e3 > e4/e4, ao passo que em Ponta Delgada e independentemente da condição fisiológica foi: e3/e3 > e2/e3 > e3/e4. Distintas frequências genotípicas foram observadas entre homens e mulheres no grupo saudável de Ponta Delgada. O índice de massa corporal, hipertensão arterial e perfil lipídico, factores de risco associados ao processo aterosclerótico, revelaram algumas diferenças quando avaliados em função dos grupos alélicos. Neste estudo, os genótipos de risco da apo E, e2/e2 and e2/e4, não foram contabilizados. Curiosamente a proporção dos genótipos nas mulheres foi heterogénea nos 3 grupos estudados.
- A Novel Short-Step Synthesis of New Xanthenedione Derivatives from the Cyclization of 3-Cinnamoyl-2-styrylchromonesPublication . Pinto, Diana C. G. A.; Seca, Ana M. L.; Leal, Stephanie B.; Silva, Artur M. S.; Cavaleiro, José A. S.Novel (E)-3-aryl-4-benzylidene-8-hydroxy-3,4-dihydro-1 H-xanthene-1,9(2H)-diones are prepared by the cyclization of (E,E)-3-cinnamoyl-5-hydroxy-2-styrylchromones efficiently catalyzed with boron tribromide. The (E,E)-3-cinnamoyl-5-hydroxy-2-styrylchromones are obtained from the Baker–Venkataraman rearrangement of (E,E)-2-acetyl-1,3-phenylene bis(3-phenylacrylate), which is greatly improved under microwave irradiation.