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- Total antioxidant activity and trace elements in human milk: the first 4 months of breast-feedingPublication . Matos, Carla; Moutinho, Carla; Balcão, Victor; Almeida, Cristina; Ribeiro, Marta; Marques, Agostinho Franklim; Guerra, AntónioThe content of many nutrients in breast milk are dependent on the nutritional status of the lactating woman. This is particularly true for fat and water-soluble vitamins, some of which have antioxidant properties. The aim of the study entertained herein was to evaluate the changes in total antioxidant status of human milk during the first 4 months of lactation, and to correlate such changes with the contents in specific antioxidant oligoelements (Cu, Zn, Mn and Se). Milk samples were collected from (31) lactating women recruited at the Service of Obstetrics of the Hospital de São João in Porto, after 1, 4, 8, 12 and 16 weeks after birth. The total antioxidant status (TAS) of human milk was measured by the Randox® commercial kit and trace metals by ICP-MS (inductively coupled plasma-mass spectrometry). The results found for TAS and oligoelements under study show a decrease in the concentration of these parameters from 7 days to 4 months of breast-feeding and significant correlations (p < 0.05) were found between TAS and Cu, Zn and Se (not Mn). The decreases of Cu, Zn and Se were also correlated, but not proportional between them, suggesting diverse excretion mechanisms for all. Between primipara and multipara women, a significant difference was found only for Cu and Zn concentrations at 7 days of lactation, but not for the other metals or TAS. With respect to the mother’s age, no correlation was found, either for trace metal concentrations or TAS.
- Fatty Acid Profile of Human Milk of Portuguese Lactating Women: Prospective Study from the 1st to the 16th Week of LactationPublication . Ribeiro, M.; Balcão, Victor; Guimaraes, H.; Rocha, G.; Moutinho, Carla; Matos, Carla; Almeida, Cristina; Casal, S.; Guerra, A.Background/Aims: Fatty acid (FA) composition varies over the course of the day and during lactation. The aim of this study was to evaluate FA composition and its compositional stability in human milk, from day 7 to week 16 of lactation. Methods: Human milk was collected from all feedings over 24 h at day 7 and weeks 4, 8, 12 and 16 of lactation in 31 lactating women. FAs were analyzed through gas chromatography. Comparisons were made with analysis of variance. Results: Total monounsaturated FAs decreased from 33.04 ± 2.58% wt/wt at day 7 to 31.48 ± 3.32% wt/wt at week 16 of lactation, much at the expenses of the decrease in the major monounsaturated FA found in human milk, oleic acid. Main polyunsaturated FAs n-6 and n-3 showed fluctuations from day 7 up to week 16 of lactation, but with no statistical significance. Arachidonic acid significantly decreased from transitional to mature milk. Conclusions: The FA profile obtained throughout the study time points presented very low levels of oleic acid and very high linoleic acid/α-linoleic acid ratios which reflect recent changes in Portuguese women’s food patterns. Despite this, the ascorbate/dehydroascorbate ratio remained constant during the study, suggesting a protective metabolic mechanism.
- Alimentos potenciadores de saúde: produtos lácteos probióticosPublication . Balcão, Victor; Moutinho, Carla; Matos, Carla; Almeida, CristinaOs alimentos probióticos em geral têm sido definidos como sendo “suplementos alimentares incorporando microorganismos vivos (bactérias probióticas) que afectam beneficamente o hospedeiro, melhorando o equilíbrio da sua microflora a nível intestinal”. O leite e os produtos lácteos em geral contêm vários biocomponentes que fornecem elementos nutritivos críticos e protecção imunológica, bem como substâncias biologicamente activas tanto a recém-nascidos como a adultos, pelo que estes alimentos pertencem ao grupo dos chamados alimentos funcionais. Produtos alimentares à base de leite inteiro ou lácteos fortificados ou enriquecidos podem, de facto, produzir efeitos potencialmente benéficos na melhoria da saúde humana e na prevenção de doenças, quando consumidos como parte de uma dieta variada e de forma regular.
- Alimentos transgénicos: questões de biosegurançaPublication . Moutinho, Carla; Balcão, Victor; Matos, Carla; Almeida, CristinaAs técnicas de modificação genética (MG), suportadas pela tecnologia de DNA recombinante, encerram um tremendo potencial para oferecer melhorias muito significativas na quantidade, qualidade e aceitabilidade dos alimentos a nível mundial. Investigadores e técnicos e engenheiros alimentares podem apoiar a introdução responsável de técnicas de MG desde que sejam satisfatoriamente considerados problemas de segurança (alimentar) do produto, preocupações ambientais, informação ao consumidor e ética. Apenas desta forma se poderão traduzir os benefícios que a tecnologia de DNA recombinante pode trazer, quanto mais não seja para ajudar a alimentar a sempre em crescimento população mundial nas próximas décadas.
- Alterações na composição lipídica do leite materno durante as primeiras dezasseis semanas de amamentaçãoPublication . Matos, Carla; Moutinho, Carla; Almeida, Cristina; Pereira, Adriana; Balcão, Victor; Ribeiro, Marta; Guimarães, Hercília; Rocha, Gustavo; Guerra, AntónioO estudo realizado teve como objectivo a avaliação da composição de ácidos gordos (AG) no leite materno aos 7 dias e 4, 8, 12 e 16 semanas de lactação. A metodologia para a extracção da gordura do leite materno foi adaptada da norma ISO 14156:2001. Os ácidos gordos foram quantificados após derivatização, com base na norma ISO 15885:2002, por cromatografia gasosa com detector por ionização em chama. Concluiu-se com este trabalho de investigação que o decréscimo na percentagem dos ácidos araquidónico (AA) e docosahexaenóico (DHA), para o valor total de AG, não se traduz num aporte desequilibrado destas moléculas para o lactente, dado que, o que realmente importa, é o rácio estável destes AG ao longo do período de lactação. The research effort described herein has as main goal the evaluation of the fatty acid composition (AG) in human mother’s milk at 7 days and 4, 8, 12 and 16 weeks of breastfeeding after giving birth. The methodology used for the extraction of fat in human milk was adapted from the ISO 14156:2001 norm. Individual fatty acids were quantified by gas chromatography (GC-FID) with flame ionization detector, after derivatization, following the procedure described in the ISO 15885:2002 norm. As a major conclusion evolving from the results obtained in this research effort, the decrease in the percentage of arachidonic (AA) and docosahexaenoic (DHA) acids, relative to the total content of fatty acids (AG), does not translate into an unbalanced uptake of these molecules by the suckling baby, since that, what really matters, is the stable ratio of these fatty acids throughout the lactation period.
- Trace element compositional changes in human milk during the first four months of lactationPublication . Matos, Carla; Moutinho, Carla; Almeida, Cristina; Guerra, António; Balcão, VictorThe aims of this paper were to evaluate changes in specific oligoelements in human milk during the first four months of lactation and to correlate such changes with total antioxidant status (TAS) and other parameters, such as the mother's age, primipara versus multipara, and supplement intake. Milk samples were collected from 31 lactating women following 1, 4, 8, 12 and 16 weeks after birth. Trace levels of 13 elements were measured by inductively coupled plasma-mass spectrometry (ICP-MS). The results obtained for the oligoelements exhibited a decrease in concentration from 7 days to 4 months of breast-feeding, with exceptions. Correlations were found between TAS and Co, V, Rb and Tl. Between primipara and multipara, differences were found for Ni and Rb. Regarding the mother's age, correlation was found for Rb and Ba (increased for mothers older than 30 years). Increased amounts of Rb, Mo and Tl at any lactation period appeared in women who took supplements.
- Processos automáticos de titulação baseados em sistemas discretos e de fluxo – evolução ao longo dos temposPublication . Moutinho, Carla; Matos, Carla; Almeida, Cristina; Balcão, VictorThe continuous necessity of create new analytical methods and to adapt them to the increasing demands of control and monitoring have promote the appearance and development of many areas of analytical chemistry, as well as the interest about automatization of methods of analysis. Automatic methods of analysis had assumed a great importance, namely, in clinical chemistry and in a level of the environmental control. The automatic needs pass, also, for the titrations, as a result of a crescent search for this king of analysis in samples of different origins. So, in this article is doing a revision about the titration systems (discrete and automatic) described, until date, in the literature.
- Moléculas anfifílicas - lípidos - e formação de agregados supramoleculares: micelas e lipossomasPublication . Moutinho, Carla; Matos, Carla; Almeida, Cristina; Balcão, VictorThe ability for self-organization of amphiphilic molecules (lipids), forming structurally more complex systems, from micelles to liposomes, constitutes the basic foundation for many biological phenomena. Lipids, for presenting important physiological roles, correlated with their particular structure and self-aggregation properties, are an interesting field of research and development. A detailed study of the micellar and membranar environment is fundamental to the knowledge of micelle´s and liposome´s capacity of acting as solubilization enhancers, what would allow the gathering of valuable information about drug´s mechanisms of transportation throw biomembranes. Assessment of the multiple amphiphilic molecule´s characteristics, together with the evaluation of the organized structures formed, is of the best interest for the comprehension of certain physiological functions, namely absorption, distribution and dynamics of certain compounds in the human organism.
- Caracterização de modelos biomembranares (micelas e lipossomas) para a determinação de coeficientes de partiçãoPublication . Matos, Carla; Moutinho, Carla; Almeida, Cristina; Balcão, VictorA drug´s mechanism of action is dependent and related to its chemical structure and, in the bottom line, to the ability of the structure to interact with biological systems. The phospholipid composed cell membrane is a particularly important system for the pharmacological action of a drug, hence pharmacokinetic parameters are generally related with the drug/membrane interaction. This interaction is dependent on the hydrophilic/lipophilic balance of the drug, a parameter traditionally assessed by the organic solvent/water partition coefficient. Liposomes and micelles, due to their composition and physical organization, can constitute basic structural models for the cell membrane, being a precious tool in drug/membrane interaction studies. The use of these simpler models allows for the comprehension of basic processes, from which a progressive complexity can be added to the system, for a progressive insight of the involved phenomena. In this context, the determination of the liposome/water, or micelle/water partition coefficients, can constitute an indicative parameter of the drug´s real behaviour in the biological system.