PT Government Associate Laboratory

Braga, Portugal

PT Government Associate Laboratory

Braga, Portugal

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Caridade S.G.,University of Minho | Caridade S.G.,PT Government Associate Laboratory | Caridade S.G.,CNRS Materials and Physical Engineering Laboratory | Monge C.,CNRS Materials and Physical Engineering Laboratory | And 5 more authors.
Biomacromolecules | Year: 2013

Free-standing films have increasing applications in the biomedical field as drug delivery systems for wound healing and tissue engineering. Here, we prepared free-standing membranes by the layer-by-layer assembly of chitosan and alginate, two widely used biomaterials. Our aim was to produce a thick membrane and to study the permeation of model drugs and the adhesion of muscle cells. We first defined the optimal growth conditions in terms of pH and alginate concentration. The membranes could be easily detached from polystyrene or polypropylene substrate without any postprocessing step. The dry thickness was varied over a large range from 4 to 35 μm. A 2-fold swelling was observed by confocal microscopy when they were immersed in PBS. In addition, we quantified the permeation of model drugs (fluorescent dextrans) through the free-standing membrane, which depended on the dextran molecular weight. Finally, we showed that myoblast cells exhibited a preferential adhesion on the alginate-ending membrane as compared to the chitosan-ending membrane or to the substrate side. © 2013 American Chemical Society.

Nebenzahl-Guimaraes H.,Harvard University | Nebenzahl-Guimaraes H.,National Institute for Public Health and the Environment RIVM | Nebenzahl-Guimaraes H.,University of Minho | Nebenzahl-Guimaraes H.,PT Government Associate Laboratory | And 4 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2014

Background: Improving our understanding of the relationship between the genotype and the drug resistance phenotype of Mycobacterium tuberculosis will aid the development of more accurate molecular diagnostics for drug-resistant tuberculosis. Studies that use direct genetic manipulation to identify the mutations that cause M. tuberculosis drug resistance are superior to associational studies in elucidating an individual mutation's contribution to the drug resistance phenotype. Methods: We systematically reviewed the literature for publications reporting allelic exchange experiments in any of the resistance-associated M. tuberculosis genes. We included studies that introduced single point mutations using specialized linkage transduction or site-directed/in vitro mutagenesis and documented a change in the resistance phenotype. Results: We summarize evidence supporting the causal relationship of 54 different mutations in eight genes (katG, inhA, kasA, embB, embC, rpoB, gyrA and gyrB) and one intergenic region (furA-katG) with resistance to isoniazid, the rifamycins, ethambutol and fluoroquinolones. We observed a significant role for the strain genomic background in modulating the resistance phenotype of 21 of these mutations and found examples of where the same drug resistance mutations caused varying levels of resistance to different members of the same drug class. Conclusions: This systematic review highlights those mutations that have been shown to causally change phenotypic resistance in M. tuberculosis and brings attention to a notable lack of allelic exchange data for several of the genes known to be associated with drug resistance. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.

Baptista M.S.,University of Minho | Baptista M.S.,PT Government Associate Laboratory | Duarte C.B.,University of Coimbra | Maciel P.,University of Minho | Maciel P.,PT Government Associate Laboratory
Cellular and Molecular Life Sciences | Year: 2012

In addition to its central roles in protein quality control, regulation of cell cycle, intracellular signaling, DNA damage response and transcription regulation, the ubiquitin- proteasome system (UPS) plays specific roles in the nervous system, where it contributes to precise connectivity through development, and later assures functionality by regulating a wide spectrum of neuron-specific cellular processes. Aberrations in this system have been implicated in the etiology of neurodevelopmental and neurodegenerative diseases. In this review, we provide an updated viewon the UPS and highlight recent findings concerning its role in normal and diseased nervous systems. We discuss the advantages of the model organism Caenorhabditis elegans as a tool to unravel the major unsolved questions concerning this biochemical pathway and its involvement in nervous system function and dysfunction, and expose the new possibilities, using state-of-the-art techniques, to assess UPS function using this model system. © 2012 Springer Basel AG.

Costa R.R.,University of Minho | Costa R.R.,PT Government Associate Laboratory | Custodio C.A.,University of Minho | Arias F.J.,University of Valladolid | And 4 more authors.
Small | Year: 2011

In this work, biomimetic smart thin coatings using chitosan and a recombinant elastin-like recombinamer (ELR) containing the cell attachment sequence arginine-glycine-(aspartic acid) (RGD) are fabricated through a layer-by-layer approach. The synthetic polymer is characterized for its molecular mass and composition using mass spectroscopy and peptide sequencing. The adsorption of each polymeric layer is followed in situ at room temperature and pH 5.5 using a quartz-crystal microbalance with dissipation monitoring, showing that both polymers can be successfully combined to conceive nanostructured, multilayered coatings. The smart properties of the coatings are tested for their wettability by contact angle (CA) measurements as a function of external stimuli, namely temperature, pH, and ionic strength. Wettability transitions are observed from a moderate hydrophobic surface (CAs approximately from 62° to 71°) to an extremely wettable one (CA considered as 0°) as the temperature, pH, and ionic strength are raised above 50 °C, 11, and 1.25 M, respectively. Atomic force microscopy is performed at pH 7.4 and pH 11 to assess the coating topography. In the latter, the results reveal the formation of large and compact structures upon the aggregation of ELRs at the surface, which increase water affinity. Cell adhesion tests are conducted using a SaOs-2 cell line. Enhanced cell adhesion is observed in the coatings, as compared to a coating with a chitosan-ending film and a scrambled arginine-(aspartic acid)-glycine (RDG) biopolymer. The results suggest that such films could be used in the future as smart biomimetic coatings of biomaterials for different biomedical applications, including those in tissue engineering or in controlled delivery systems. Nanostructured multilayered films of chitosan and an elastin-like recombinamer are constructed. The thin films are demonstrated to possess stimuli-responsive and cyclic wettability changes from moderately hydrophobic to superhydrophilic, accompanied by the formation of spherical "micelle-like" structures. The incorporation of arginine-glycine-aspartic acid (RGD) in the recombinamer sequence improved cell adhesion. These features make of this system a promising alternative to classical layer-by-layer films with smart nature and increased functionality. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cotter J.,Centro Hospitalar do Alto Ave | Cotter J.,University of Minho | Cotter J.,PT Government Associate Laboratory | Dias de Castro F.,Centro Hospitalar do Alto Ave | And 2 more authors.
Journal of Crohn's and Colitis | Year: 2014

Background and aims: Small bowel capsule endoscopy (SBCE) may detect proximal small bowel lesions that have been previously missed by ileocolonoscopy and small bowel imaging in patients with known ileal and/or colonic Crohn's disease (CD). We aimed to evaluate whether the therapeutic management is influenced by SBCE findings. Methods: Retrospective single center study. Inclusion of consecutive patients with known non-stricturing and non-penetrating ileal and/or colonic CD, submitted to SBCE to evaluate disease extension and activity, with ≥ 1. year follow-up. Lesions were classified with the Lewis score (LS) as non-significant (LS. <. 135), mild (135. ≤. LS. ≤. 790), or moderate-to-severe (LS. >. 790). Therapeutic changes were assessed three months after SBCE. Results: Fifty consecutive patients (35. ±. 13. years, 52% females) were included. At ileocolonoscopy, disease location was ileal (L1) in 60%, colonic (L2) in 10% and ileocolonic (L3) in 30% of the patients. In 33 patients (66%) SBCE detected significant proximal lesions previously missed by other modalities. The proportion of patients on thiopurines and/or biologics before SBCE was 2/50 (4%); this was significantly higher three months after SBCE, 15/50 (30%), p. = 0.023. Treatment with thiopurines and/or biologics was started more often in patients with proximal small bowel lesions [13/33 (39%) vs. 1/17 (6%), p. = 0.011, relative risk (RR) 6.5], particularly when severe (6%, 36% and 45% of patients with non-significant, mild and moderate-to-severe inflammation, respectively). Conclusions: SBCE diagnoses previously undetected lesions and it influences therapeutic management of CD, triggering an earlier introduction of immunomodulators and/or biological therapy. © 2014 European Crohn's and Colitis Organisation.

Bruchfeld J.,Karolinska University Hospital | Correia-Neves M.,University of Minho | Correia-Neves M.,PT Government Associate Laboratory | Kallenius G.,Karolinska Institutet
Cold Spring Harbor Perspectives in Medicine | Year: 2015

Tuberculosis (TB) and human immunodeficiency virus/acquired immunodeficiency syn-drome (HIV/AIDS) constitute the main burden of infectious disease in resource-limited countries. In the individual host, the two pathogens, Mycobacterium tuberculosis and HIV, potentiate one another, accelerating the deterioration of immunological functions. In high-burden settings, HIV coinfection is the most important risk factor for developing active TB, which increases the susceptibility to primary infection or reinfection and also the risk of TB reactivation for patients with latent TB. M. tuberculosis infection also has a negative impact on the immune response to HIV, accelerating the progression from HIV infection to AIDS. The clinical management of HIV-associated TB includes the integration of effective anti-TB treatment, use of concurrent antiretroviral therapy (ART), prevention of HIV-related comorbidities, management of drug cytotoxicity, and prevention/treatment of immune reconstitution inflammatory syndrome (IRIS). © 2015 Cold Spring Harbor Laboratory Press; all rights reserved.

Costa P.F.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Costa P.F.,PT Government Associate Laboratory | Vaquette C.,Queensland University of Technology | Zhang Q.,University of Sichuan | And 4 more authors.
Journal of Clinical Periodontology | Year: 2014

Aim This study investigated the ability of an osteoconductive biphasic scaffold to simultaneously regenerate alveolar bone, periodontal ligament and cementum. Materials and Methods A biphasic scaffold was built by attaching a fused deposition modelled bone compartment to a melt electrospun periodontal compartment. The bone compartment was coated with a calcium phosphate (CaP) layer for increasing osteoconductivity, seeded with osteoblasts and cultured in vitro for 6 weeks. The resulting constructs were then complemented with the placement of PDL cell sheets on the periodontal compartment, attached to a dentin block and subcutaneously implanted into athymic rats for 8 weeks. Scanning electron microscopy, X-ray diffraction, alkaline phosphatase and DNA content quantification, confocal laser microscopy, micro computerized tomography and histological analysis were employed to evaluate the scaffold's performance. Results The in vitro study showed that alkaline phosphatase activity was significantly increased in the CaP-coated samples and they also displayed enhanced mineralization. In the in vivo study, significantly more bone formation was observed in the coated scaffolds. Histological analysis revealed that the large pore size of the periodontal compartment permitted vascularization of the cell sheets, and periodontal attachment was achieved at the dentin interface. Conclusions This work demonstrates that the combination of cell sheet technology together with an osteoconductive biphasic scaffold could be utilized to address the limitations of current periodontal regeneration techniques. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Luz G.M.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Luz G.M.,PT Government Associate Laboratory | Mano J.F.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Mano J.F.,PT Government Associate Laboratory
Nanotechnology | Year: 2011

Bioactive glass nanoparticles (BG-NPs), based on both ternary (SiO 2-CaO-P2O5) and binary (SiO2-CaO) systems, were prepared via an optimized sol-gel method. The pH of preparation and the effect of heat treatment temperature were evaluated, as well as the effect of suppressing P in the bioactivity ability of the materials. The morphology and composition of the BG-NPs were studied using FTIR, XRD and SEM. The bioactive character of these materials was accessed invitro by analyzing the ability for apatite formation onto the surface after being immersed in simulated body fluid (SBF). XRD, EDX and SEM were used to confirm the bioactivity of the materials. The BG-NP effect on cell metabolic activity was assessed by seeding L929 cells with their leachables, proving the non-cytotoxicity of the materials. Finally the most bioactive BG-NPs developed (ternary system prepared at pH11.5 and treated at 700 °C) were successfully combined with chitosan in the production of biomimetic nanocomposite osteoconductive membranes that could have the potential to be used in guided tissue regeneration. © IOP Publishing Ltd.

Oliveira N.M.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Oliveira N.M.,PT Government Associate Laboratory | Reis R.L.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Reis R.L.,PT Government Associate Laboratory | And 2 more authors.
ACS Applied Materials and Interfaces | Year: 2013

We present a simple method to prepare superhydrophobic surfaces using siliceous exoskeleton of diatoms, a widespread group of algae. This makes diatomaceous earth an accessible and cheap natural material. A micro/nanoscale hierarchical topography was achieved by coating a glass surface with diatomaceous earth, giving rise to a superhydrophilic surface. Superhydrophobic surfaces were obtained by a further surface chemical modification through fluorosilanization. The wettability of the superhydrophobic surface can be modified by Argon plasma treatment in a controlled way by exposure time variation. The chemical surface modification by fluorosilanization and posterior fluorinated SH surface modification by plasma treatment was analyzed by XPS. Using appropriated hollowed masks only specific areas on the surface were exposed to plasma permitting to pattern hydrophilic features with different geometries on the superhydrophobic surface. We showed that the present strategy can be also applied in other substrates, including thermoplastics, enlarging the potential applicability of the resulting surfaces. © 2013 American Chemical Society.

Lima A.C.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Lima A.C.,PT Government Associate Laboratory | Mano J.F.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Mano J.F.,PT Government Associate Laboratory
Nanomedicine | Year: 2015

The properties of surfaces define the acceptance and integration of biomaterials in vivo, as well as the material's efficiency when used at research or manufacturing levels. The presence of micro/nano-topographical structures and low surface energies could bring several advantages when highly repellent surfaces are employed in the biomedical field. Biomimetic superhydrophobic surfaces have been explored for diverse applications: as an intrinsic characteristic of biomaterials to be implanted; as materials that exhibit special interactions with biological entities; or to be used in ex vivo applications. This article aims to focus on the main motivations and requirements in the biomedical field that pushed for the utilization of superhydrophobic surfaces as suitable alternatives, as well as the great evolution of applications that have emerged in the last few years. © 2015 Future Medicine Ltd.

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