Browsing by Author "Ribeiro, Marta"
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- 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.
- Development of silk fibroin/nanohydroxyapatite composite hydrogels for bone tissue engineeringPublication . Ribeiro, Marta; Moraes, Mariana A. de; Beppu, Marisa M.; Garcia, Mónica P.; Fernandes, Maria H.; Monteiro, Fernando J.; Ferraz, Maria PiaThis work presents a novel composite hydrogel consisting of silk fibroin (SF) and nanohydroxyapatite (nanoHA) prepared by a new and innovative method using ethanol as gelling agent capable of forming hydrogels in few minutes. The properties of the composite material, such as the microstructure as well as the chemical and physical properties were studied. Moreover in␣vitro studies of osteoblastic citocompatibility were performed. The microporosity and macroporosity obtained combined with interconnected porous structure and a uniform dispersion of nanoHA particles throughout the fibroin matrix makes composite hydrogel suitable for bone regeneration. The compression modulus of composite hydrogels was increased as the nanoHA concentration increased from 10 to 15 wt.% and the water uptake ability of these materials decreased with the incorporation of nanoHA. The metabolic and alkaline phosphatase activities of osteoblastic cells were improved with the incorporation of nanoHA in the SF matrix providing a more promising material for bone tissue engineering.
- Silk fibroin/nanohydroxyapatite hydrogels for promoted bioactivity and osteoblastic proliferation and differentiation of human bone marrow stromal cellsPublication . Ribeiro, Marta; Fernandes, Maria H.; Beppu, Marisa M.; Monteiro, Fernando J.; Ferraz, Maria PiaSilk fibroin (SF) is a natural, biocompatible, and biodegradable polymer having a great potential for the successful regeneration of damaged bone tissue. In the present work, nanohydroxyapatite (nanoHA) was incorporated into SF polymer to form a bioactive composite hydrogel for applications as bone implants. The degradation and bioactive properties of SF/nanoHA composite hydrogels were evaluated. Additionally, biological investigations of human bone marrow stromal cells (hBMSCs) viability, proliferation and differentiation to the osteoblastic phenotype were conducted. The incorporation of nanoHA in SF polymer matrices improved the bioactivity of the hydrogels. The biological results highlighted that the SF/nanoHA composite hydrogels are suitable for hBMSCs attachment and proliferation, while a test for alkaline phosphatase (ALP) and bone morphogenetic protein 2 (BMP-2) expression suggested osteoblast differentiation. Additionally, a cell staining method for ALP allowed to observe cell infiltration with active production of ALP by the infiltrated cells, paving the way to use the proposed composite hydrogel for bone tissue regeneration.
- 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.