Dynamic mechanical properties of hydroxyapatite-reinforced and porous starch-based degradable biomaterials

It has been shown that blends of starch with a poly(ethylene-vinyl-alcohol) copolymer, EVOH, designated as SEVA-C, present an interesting combination of mechanical, degradation and biocompatible properties, specially when filled with hydroxyapatite (HA). Consequently, they may find a range of applications in the biomaterials field. This work evaluated the influence of HA fillers and of blowing agents (used to produce porous architectures) over the viscoelastic properties of SEVA-C polymers, as seen by dynamic mechanical analysis (DMA), in order to speculate on their performances when withstanding cyclic loading in the body. The composite materials presented a promising performance under dynamic mechanical solicitation conditions. Two relaxations were found being attributed to the starch and EVOH phases. The EVOH relaxation process may be very useful in vivo improving the implants performance under cyclic loading. DMA results also showed that it is possible to produce SEVA-C compact surface/porous core architectures with a mechanical performance similar to that of SEVA-C dense materials. This may allow for the use of these materials as bone replacements or scaffolds that must withstand loads when implanted

Percepção de segurança em um parque urbano não cercado e hipoteticamente cercado

O objetivo deste artigo é identificar a percepção de segurança em um parque urbano não cercado, o Parque Farroupilha, e em caso de um cercamento hipotético, por parte de três grupos relacionados ao parque: usuários do Parque Farroupilha que estavam praticando alguma atividade no local; moradores dos bairros do entorno do parque (Santana, Farroupilha, Bom Fim e Cidade Baixa); e comerciantes que exercem atividades em edificações do entorno, ambulantes do Parque Farroupilha, bem como expositores da Feira Ecológica/Brique Redenção. Adicionalmente, são revelados os locais do Parque não utilizados pelos respondentes por sentirem-se inseguros; as ocorrências criminais no Parque e nas proximidades; e a percepção de segurança no caso de um cercamento hipotético. Os dados foram coletados através de questionários e analisados através de testes estatísticos não-paramétricos. Ainda, foram utilizados dados sobre ocorrências criminais, coletados junto à Secretaria de Segurança Pública do Estado do Rio Grande do Sul. Os resultados evidenciam que a percepção atual em relação à segurança no Parque Farroupilha para os três grupos é de nem seguro e nem inseguro, seguida por uma percepção de inseguro. Conforme a percepção destes grupos, o cercamento hipotético do Parque não aumentaria a percepção de segurança, ocorrendo justamente o inverso.Área temática 4: Ciudad, Territorio y Paisaje. Gestión - Eje InvestigaciónFacultad de Arquitectura y Urbanism

Percepção de segurança em um parque urbano não cercado e hipoteticamente cercado

O objetivo deste artigo é identificar a percepção de segurança em um parque urbano não cercado, o Parque Farroupilha, e em caso de um cercamento hipotético, por parte de três grupos relacionados ao parque: usuários do Parque Farroupilha que estavam praticando alguma atividade no local; moradores dos bairros do entorno do parque (Santana, Farroupilha, Bom Fim e Cidade Baixa); e comerciantes que exercem atividades em edificações do entorno, ambulantes do Parque Farroupilha, bem como expositores da Feira Ecológica/Brique Redenção. Adicionalmente, são revelados os locais do Parque não utilizados pelos respondentes por sentirem-se inseguros; as ocorrências criminais no Parque e nas proximidades; e a percepção de segurança no caso de um cercamento hipotético. Os dados foram coletados através de questionários e analisados através de testes estatísticos não-paramétricos. Ainda, foram utilizados dados sobre ocorrências criminais, coletados junto à Secretaria de Segurança Pública do Estado do Rio Grande do Sul. Os resultados evidenciam que a percepção atual em relação à segurança no Parque Farroupilha para os três grupos é de nem seguro e nem inseguro, seguida por uma percepção de inseguro. Conforme a percepção destes grupos, o cercamento hipotético do Parque não aumentaria a percepção de segurança, ocorrendo justamente o inverso.Área temática 4: Ciudad, Territorio y Paisaje. Gestión - Eje InvestigaciónFacultad de Arquitectura y Urbanism

Pulmonary hemorrhage syndrome associated with dengue fever, High-resolution computed tomography findings: a case report

Dengue hemorrhagic fever is an acute infectious disease caused by dengue virus. We described the high-resolution CT findings in a 70-year-old male with the disease, which was diagnosed by clinical examination and confirmed by serological methods. High-resolution CT demonstrated bilateral areas of consolidation with air bronchogram and ground glass opacities, as well as small bilateral pleural effusions. Dengue hemorrhagic fever should be considered in the differential diagnosis of diffuse pulmonary hemorrhage

Biomedical potential of fucoidan, a seaweed sulfated polysaccharide: from a anticancer agent to a building block of cell encapsulating systems for regenerative medicine

Marine macroalgae or seaweeds synthesize a wide variety of polymers and smaller compounds with several bioactivities, among which the sulfated polysaccharides acquire greater relevance not only due to the reported antioxidant, antiviral and anticancer[1] activities, but also to the resemblance of extracellular matrix glycosaminoglycans found in the human body[2]. In this study, the potential of fucoidan (Fu) isolated from brown seaweed Fucus vesiculosus for therapeutical use has been evaluated, focusing in its performance as antitumoral agent (bioactive role) or as building block of cell encapsulating systems (structural role). Materials and Methods: The anticancer activity of Fu extracts was assessed by evaluating the cytotoxic behavior over two human breast cancer cell lines (MCF-7 and MDA-MB-231) in in-vitro culture, using human fibroblasts and endothelial cells (HPMEC-ST1 and MRC-5, respectively) as reference. Regarding the structural role, Fu was modified by methacrylation reaction (MFu) using methacrylic acid and further crosslinked using visible radiation and triethanolamine and eosin-y as photoinitiators. The photocrosslinking was performed on MFu solution droplets placed in a silica-based superhydrophobic surface[3], allowing the formation of particles[4] (since natural Fu is highly soluble in water and ion gelation is not effective). Biological performance of the developed particles was assessed by in vitro culture of fibroblasts and pancreatic cells (L929 and 1.1B4, respectively) in contact with MFu particles, up to 7 days. The ability of the developed materials to support adhesion and proliferation of cells was evaluated for both types of cells. Results and Discussion: The tested anticancer activity is not ubiquitous on Fu extracts, being dependent on its chemical features, with molecular weight (Mw) representing a particular role. Specifically, Mw values around 60 kDa exhibited cytotoxic effects to human breast cancer cell lines, while not affecting normal fibroblasts or endothelial cells (which represent the cells of the healthy tissue that would be closer to the tumor in a real situation). A concentration range of 0.2 to 0.3 mg mL-1 from the selected Fu extract could be considered as the therapeutic window for further studies. Regarding fucoidanâ s role on innovative biomaterials, the developed MFu particles could support the proliferation of fibroblasts (L929), but also of human pancreatic beta cells (1.1B4), which tend to form pseudo-islets after 7 days in culture (Fig. 1). This pancreatic cells could be also successfully encapsulated, opening a new route for a diabetes mellitus type 1 therapeutic approach. Fig. 1: Confocal microscopy images of 1.1B4 cells cultured in the presence of fucoidan-based particles and organized in pseudo-islets (red â actin; blue â nuclei). Conclusion: The present work establishes fucoidan as a high performance building block for the development of advanced therapies for cancer (targeted therapy) or tissue and organ regeneration. It shed light on the relation between chemical structure and biological activity towards anti-cancer effect and proposes novel beta cell laden particles as injectable insulin producing systems to tackle diabetes.Funding from projects 0687_NOVOMAR_1_P (co-funded by INTERREG 2007-2013 / POCTEP), CarbPol_u_Algae (EXPL/MAR-BIO/0165/2013, funded by the Portuguese Foundation for Science and Technology, FCT), POLARIS (FP7-REGPOT-CT2012-316331) and ComplexiTE (ERC-2012-ADG 20120216-321266), funded by the European Union’s Seventh Framework Programme for Research and Development is acknowledged. ASF, SSS, NMO and DSC are also thankful to FCT for their individual fellowships

Mechanical, dynamic-mechanical, and thermal properties of soy protein-based thermoplastics with potential biomedical applications

In this study the tensile and the dynamic-mechanical behavior of injection-molded samples of various soy protein thermoplastic compounds were evaluated as a function of the amount of glycerol, type and amount of ceramic reinforcement, and eventual incorporation of coupling agents. The incorporation of glycerol into a soy-based matrix resulted in its plasticization, as confirmed by the drop in stiffness (storage and elastic modulus) above 20°C and a decrease in the protein glass transition temperature. Differential scanning calorimetric thermograms proved the occurrence of conformational changes in the soy protein during processing. Furthermore, the developed soy protein-based thermoplastics showed a thermal stability up to 100°C, as confirmed by thermogravimetric analysis. The reinforcement of the soy protein matrix with a ceramic filler (tricalcium phosphate) was shown to be effective for amounts above 10% w/w. The introduction of an amino-coupling agent led to a plasticizing effect, detected in the mechanical and dynamic-mechanical properties of the resulting materials. The results also show a good qualitative agreement between the properties obtained from quasi-static and dynamic experiments. The materials present a range of properties that might allow for their use eventually in a range of biomedical applications

S4(13)-PV cell-penetrating peptide induces physical and morphological changes in membrane-mimetic lipid systems and cell membranes: Implications for cell internalization

The present work aims to gain insights into the role of peptide–lipid interactions in the mechanisms of cellular internalization and endosomal escape of the S4(13)-PV cell-penetrating peptide, which has been successfully used in our laboratory as a nucleic acid delivery system. A S4(13)-PV analogue, S4(13)-PVscr, displaying a scrambled amino acid sequence, deficient cell internalization and drug delivery inability, was used in this study for comparative purposes. Differential scanning calorimetry, fluorescence polarization and X-ray diffraction at small and wide angles techniques showed that both peptides interacted with anionic membranes composed of phosphatidylglycerol or a mixture of this lipid with phosphatidylethanolamine, increasing the lipid order, shifting the phase transition to higher temperatures and raising the correlation length between the bilayers. However, S4(13)-PVscr, in contrast to the wild-type peptide, did not promote lipid domain segregation and induced the formation of an inverted hexagonal lipid phase instead of a cubic phase in the lipid systems assayed. Electron microscopy showed that, as opposed to S4(13)-PVscr, the wild-type peptide induced the formation of a non-lamellar organization in membranes of HeLa cells. We concluded that lateral phase separation and destabilization of membrane lamellar structure without compromising membrane integrity are on the basis of the lipid-driven and receptor-independent mechanism of cell entry of S4(13)-PV peptide. Overall, our results can contribute to a better understanding of the role of peptide–lipid interactions in the mechanisms of cell-penetrating peptide membrane translocation, helping in the future design of more efficient cell-penetrating peptide-based drug delivery systems

Engineering enriched microenvironments with gradients of platelet lysate in hydrogel fibers

Gradients of physical and chemical cues are characteristic of specific tissue microenvironments and contribute toward morphogenesis and tissue regeneration upon injury. Recent advances on microfluidics and hydrogel manipulation raised the possibility of generating biomimetic biomaterials enriched with bioactive factors and encapsulating cells following designs specifically tailored for a target application. The novelty of this work relies on the combination of methacrylated gellan gum (MeGG) with platelet lysate (PL), aiming to generate novel advanced 3D PL-enriched photo-cross-linkable hydrogels and overcoming the lack of adhesion sites provided by the native MeGG hydrogels. This combination takes advantage of the availability, enriched growth factor composition, and potential autologous application of PL while simultaneously preserving the ability provided by MeGG to tailor mechanical properties, protein release kinetics, and shape of the construct according to the desired goal. Incorporation of PL in the hydrogels significantly improved cellular adhesion and viability in the constructs. The use of microfluidic tools allowed the design of a fiber-like hydrogel incorporating a gradient of PL along the length of the fiber. These spatial protein gradients led to the viability and cell number gradients caused by maintenance of human umbilical vein endothelial cells (HUVECs) survival in the fibers toward the PL-enriched sections in comparison with the nonloaded MeGG sections of the fibers. Altogether, we propose a proof of concept strategy to design a PL gradient biomaterial with potential in tissue engineering approaches and analysis of cell-microenvironment interactions.Fundação para a Ciência e a Tecnologia (FCT) - project BIBS (PTDC/CVT/102972/2008) ; Post-Doc Fellowship SFRH/BPD/91072/2012 ; Ph.D. Grant SFRH/BD/73403/201