Time filter

Source Type

Menino J.F.,University of Minho | Menino J.F.,ICVS 3Bs PT Government Laboratory | Almeida A.J.,University of Minho | Rodrigues F.,University of Minho
Methods in Molecular Biology | Year: 2012

Paracoccidioides brasiliensis is a thermal dimorphic fungus which in the host environment exhibits a multinucleated and multibudding yeast form. The cellular and molecular mechanisms underlying these phenotypes remain to be clarified, mostly due to the absence of efficient classical genetic and molecular techniques. Here we describe a method for gene expression knockdown in P. brasiliensis by antisense RNA (aRNA) technology taking advantage of an Agrobacterium tumefaciens-mediated transformation (ATMT) system. Together, these techniques represent a reliable toolbox that can be employed for functional genetic analysis of putative virulence factors and morphogenic regulators, aiming to the identification of new potential drug targets. © 2012 Springer Science+Business Media, LLC.

Batalha V.L.,University of Lisbon | Pego J.M.,University of Minho | Pego J.M.,ICVS 3Bs PT Government Laboratory | Fontinha B.M.,University of Lisbon | And 7 more authors.
Molecular Psychiatry | Year: 2013

Maternal separation (MS) is an early life stress model that induces permanent changes in the central nervous system, impairing hippocampal long-term potentiation (LTP) and spatial working memory. There are compelling evidences for a role of hippocampal adenosine A2A receptors in stress-induced modifications related to cognition, thus opening a potential window for therapeutic intervention. Here, we submitted rats to MS and evaluated the long-lasting molecular, electrophysiological and behavioral impairments in adulthood. We then assessed the therapeutic potential of KW6002, a blocker of A2A receptors, in stress-impaired animals. We report that the blockade of A2A receptors was efficient in reverting the behavior, electrophysiological and morphological impairments induced by MS. In addition, this effect is associated with restoration of the hypothalamic-pituitary-adrenal axis (HPA-axis) activity, as both the plasma corticosterone levels and hippocampal glucocorticoid receptor expression pattern returned to physiological-like status after the treatment. These results reveal the involvement of A2A receptors in the stress-associated impairments and directly in the stress response system by showing that the dysfunction of the HPA-axis as well as the long-lasting synaptic and behavioral effects of MS can be reverted by targeting adenosine A2A receptors. These findings provide a novel evidence for the use of adenosine A2A receptor antagonists as potential therapy against psychopathologies. © 2013 Macmillan Publishers Limited.

Tavares-Valente D.,Institute Investigacao e Formacao Avancada em Ciencias e Tecnologias da Saude | Baltazar F.,University of Minho | Baltazar F.,ICVS 3Bs PT Government Laboratory | Moreira R.,Institute Investigacao e Formacao Avancada em Ciencias e Tecnologias da Saude | And 3 more authors.
Journal of Bioenergetics and Biomembranes | Year: 2013

The multidrug resistance (MDR) phenotype, frequently observed during cancer treatment, is often associated with drug efflux pump activity. However, many other factors are also known to be involved. Cancer cells often rely on aerobic glycolysis for energy production; this is known as the "Warburg effect" and is used as a survival mechanism. Associated to this event, a reverse pH gradient across the cell membrane occurs, leading to cytosol alkalinization and extracellular acidification. In the present study, we investigated the role of different mechanisms involved in MDR, such as altered tumor microenvironment and energetic metabolism. The breast cancer cell line MCF-7, used as model, was exposed to two widely used antitumor drugs, paclitaxel (antimitotic agent) and doxorubicin (alkylating agent). Cancer pH regulation was shown to be crucial for malignant characteristics such as cell migration and drug resistance. Our results showed that a lower extracellular pH induced a higher migratory capacity and higher resistance to the studied chemotherapeutical compounds in MCF-7 cells. Besides the influence of the extracellular pH, the role of the tumor metabolism in the MDR phenotype was also investigated. Pre-treatment with different bioenergetic modulators led to cell ATP depletion and altered lactic acid production and glucose consumption, resulting in increased sensitivity to paclitaxel and doxorubicin. Overall, this study supports the potential use of compounds targeting cell metabolism and tumor microenvironment factors such as pH, as co-adjuvants in conventional chemotherapy. © 2013 Springer Science+Business Media New York.

Luz G.M.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Luz G.M.,ICVS 3Bs PT Government Laboratory | Boesel L.,Max Planck Institute for Polymer Research | Campo A.D.,Max Planck Institute for Polymer Research | And 2 more authors.
Langmuir | Year: 2012

Bioactive glass nanoparticles (BG-NPs) capable of inducing apatite precipitation upon immersion in simulated body fluid (SBF) were patterned on free-standing chitosan membranes by microcontact printing using a poly(dimethylsiloxane) (PDMS) stamp inked in a BG-NPs pad. Formation of the patterns was characterized by scanning electron microscopy (SEM). Mineralization of the bioactive glass patterns was induced in vitro by soaking the samples in SBF over different time points up to 7 days. The confined apatite deposition in the patterned regions with diameters of 50 μm was confirmed by Fourier-transformed infrared spectroscopy (FTIR), energy-dispersive X-ray (EDX) analysis, and SEM. In vitro tests confirmed the preferential attachment and proliferation of L929 cells to the areas printed with BG-NPs of the membranes. This approach permits one to spatially control the properties of biomaterials at the microlevel and could be potentially used in guided tissue regeneration for skin, vascular, articular, and bone tissue engineering and in cellular cocultures or to develop substrates able to confine cells in regions with controlled geometry at the cell's length scale. © 2012 American Chemical Society.

Rodrigues A.I.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Gomes M.E.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Leonor I.B.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Leonor I.B.,ICVS 3Bs PT Government Laboratory | And 2 more authors.
Acta Biomaterialia | Year: 2012

Silicon is known to have an influence on calcium phosphate deposition and on the differentiation of bone precursor cells. This study explores the effect of the incorporation of silanol (Si-OH) groups into polymeric scaffolds on the osteogenic differentiation of human adipose stem cells (hASC) cultured under dynamic and static conditions. A blend of corn starch with polycaprolactone (30/70 wt.%, SPCL) was used to produce three-dimensional fibre meshes scaffolds by the wet-spinning technique, and a calcium silicate solution was used as a non-solvent to develop an in situ functionalization with Si-OH groups. In vitro assessment, using hASC, of functionalized and non-functionalized scaffolds was evaluated in either α-MEM or osteogenic medium under static and dynamic conditions (provided by a flow perfusion bioreactor). The functionalized materials, SPCL-Si, exhibit the capacity to sustain cell proliferation and induce their differentiation into the osteogenic lineage. The formation of mineralization nodules was observed in cells cultured on the SPCL-Si materials. Culturing under dynamic conditions using a flow perfusion bioreactor was shown to enhance the hASC proliferation and differentiation and a better distribution of cells within the material. The present work demonstrates the potential of these functionalized materials for future applications in bone tissue engineering. Additionally, these results highlight the simplicity, economic and reliable production process of those materials. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Discover hidden collaborations