Glutaraldehyde-crosslinking chitosan scaffolds reinforced with calcium phosphate spray-dried granules for bone tissue applications

The clinical demand for bone scaffolds as an alternative strategy for bone grafting has increased exponentially and, up to date, numerous formulations have been proposed to regenerate the bone tissue. However, most of these structures lack at least one of the fundamental/ideal properties of these materials (e.g., mechanical resistance, interconnected porosity, bioactivity, biodegradability, etc.). In this work, we developed innovative composite scaffolds, based on crosslinked chitosan with glutaraldehyde (GA), combined with different atomized calcium phosphates (CaP) granules - hydroxyapatite (HA) or biphasic mixtures of HA and β - tricalcium phosphate (β-TCP), with improved biomechanical behavior and enhanced biological response. This innovative combination was designed to improve the scaffolds' functionality, in which GA improved chitosan mechanical strength and stability, whereas CaP granules enhanced the scaffolds' bioactivity and osteoblastic response, further reinforcing the scaffolds' structure. The biological assessment of the composite scaffolds showed that the specimens with 0.2% crosslinking were the ones with the best biological performance. In addition, the inclusion of biphasic granules induced a trend for increase osteogenic activation, as compared to the addition of HA granules. In conclusion, scaffolds produced in the present work, both with HA granules or the biphasic ones, and with low concentrations of GA, have shown adequate properties and enhanced biological performance, being potential candidates for application in bone tissue engineering.publishe

Ocorrência de eflorescências sulfatadas na mina de São Domingos

The intense exploration of sulphide ore deposit in São Domingos mine, produced considerable amount of sulphide material that when are exposed to weathering generates acid mine drainage (AMD). The main goal of this paper is to study a specific occurrence regarding composition and morphology of the salts that arise at the end of the dry season. Soluble salts appear at the banks of the drainage channels and over the waste materials, exhibiting different colours and aspects. The obtained results showed by X-Ray diffraction and scanning electronic microscopy, that the mineralogy of salt efflorescences is dominated by sulphates, displaying different occurrence modes. Melanterite and copiapite are the main iron sulphates while minerals from the series of pickeringite-halotrichite dominate the aluminium sulphates. In addition, dehydration and dissolution laboratory experiments were carried out in order to simulate the transformations suffered by soluble salts and evaluate the environmental effect in aquatic system.Patrícia Gomes wishes to acknowledge FCT (Science and Technology Foundation, Portugal) by the research fellowship under the POCH (Programa Operacional Capital Humano) supported by the European Social Fund and National Funds of MCTES with reference SFRH/BD/108887/2015. This work was co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalização), project ICT (UID/GEO/04683/2013) with reference POCI-01-0145-FEDER-007690 and national funds provided by FCT (Science and Technology Foundation, Portugal)

Cost effectiveness of OptiMal® rapid diagnostic test for malaria in remote areas of the Amazon Region, Brazil

<p>Abstract</p> <p>Background</p> <p>In areas with limited structure in place for microscopy diagnosis, rapid diagnostic tests (RDT) have been demonstrated to be effective.</p> <p>Method</p> <p>The cost-effectiveness of the Optimal^®and thick smear microscopy was estimated and compared. Data were collected on remote areas of 12 municipalities in the Brazilian Amazon. Data sources included the National Malaria Control Programme of the Ministry of Health, the National Healthcare System reimbursement table, hospitalization records, primary data collected from the municipalities, and scientific literature. The perspective was that of the Brazilian public health system, the analytical horizon was from the start of fever until the diagnostic results provided to patient and the temporal reference was that of year 2006. The results were expressed in costs per adequately diagnosed cases in 2006 U.S. dollars. Sensitivity analysis was performed considering key model parameters.</p> <p>Results</p> <p>In the case base scenario, considering 92% and 95% sensitivity for thick smear microscopy to <it>Plasmodium falciparum </it>and <it>Plasmodium vivax</it>, respectively, and 100% specificity for both species, thick smear microscopy is more costly and more effective, with an incremental cost estimated at US$549.9 per adequately diagnosed case. In sensitivity analysis, when sensitivity and specificity of microscopy for <it>P. vivax </it>were 0.90 and 0.98, respectively, and when its sensitivity for <it>P. falciparum </it>was 0.83, the RDT was more cost-effective than microscopy.</p> <p>Conclusion</p> <p>Microscopy is more cost-effective than OptiMal^®in these remote areas if high accuracy of microscopy is maintained in the field. Decision regarding use of rapid tests for diagnosis of malaria in these areas depends on current microscopy accuracy in the field.</p

Chitosan–lignosulfonates sono-chemically prepared nanoparticles : characterisation and potential applications

Due to their recognised properties of biocompatibility, biodegradability and sustainability, chitosan nanocarriers have been successfully used as new delivery systems. In this work, nanoparticles combining chitosan and lignosulfonates were developed for the first time for cosmetic and biomedical applications. The ability of lignosulfonates to act as a counter polyion for stabilisation of chitosan particles, generated using high intensity ultrasound, was investigated. Several conditions for particles preparation were tested and optimised and the resulting nanoparticles were comprehensively characterised by measuring particle size, zeta potential and polydispersity index. The pH of chitosan solution, sonication time and the presence of an adequate surfactant, poloxamer 407, were determinant factors on the development of smaller particles with low polydispersity index (an average particle size of 230 nm was obtained at pH 5 after 8 min of sonication). The beneficial effects of lignosulfonates complex on chitosan nanoparticles were further characterised. Greater stability to lysozyme degradation, biocompatibility with human cells and antimicrobial activity was found upon lignosulfonates incorporation into chitosan nanoparticles. Furthermore, these particles were able to incorporate a hydrophilic model protein – RNase A. A burst release was observed when nanoparticles were loaded with low amount of protein while with high protein content, a sustained release was found, suggesting that the protein cargo maybe loaded both at the surface as in the bulk of the particle, depending on the concentration of drug incorporated.This work was financed by FP6 European project BioRenew (contract no. NMP2-CT-2006-026456), and by FEDER through POFC-COMPETE and by national funds from FCT through the project PEst-C/BIA/UI4050/2011. FCT - Portuguese Foundation for Science and Technology awarded scholarships to M.M. Fernandes (SFRH/BD/38363/2007), T. Matama (SFRH/BPD/47555/2008) and A. Loureiro (SFRH/BD/81479/2011)

Metals and arsenic enrichment processes in sulfide-rich waste dumps - the role of the clay size fraction

[Extract] 1. Purpose Abandoned mines pose some of the most outstanding environmental risks, namely related with potentially toxic metals and metalloids in mining soils. Mobilization or fixation of these elements in the soil particles can be regulated by the interactions between several biogeochemical and mineralogical processes. In this context, the present study is focused on the detection of metals and arsenic enrichment processes in different particle size fractions of two distinctive sulphide-rich waste dumps. Furthermore, the study evaluates the role of typical clay size minerals, such as oxyhydroxides and clay minerals in the retention of toxic elements...info:eu-repo/semantics/publishedVersio

Indicators of acid mine drainage in an affected system: the case of the mine Santo António de Penedono

O presente estudo descreve os efeitos da evolução geoquímica e mineralógica dos resíduos mineiros acumulados na escombreira de Santo António de Penedono, Penedono. Mediante a aplicação de diferentes tipos de indicadores: físico-químicos, ecológicos e mineralógicos, descrevem-se as propriedades do ambiente de drenagem superficial. Os resultados demonstram o caráter ácido do efluente e sugerem a eficácia de algas acidófilas como indicadoras de contaminação mineira. A análise mineralógica põe em evidência o papel dos precipitados de drenagem ácida no controle da mobilidade de poluentes, em especial do arsénio.The present study describes the effects of geochemical and mineralogical evolution of Penedono mine waste-dumps by applying different types of indicators: physical-chemical, ecological and mineralogical. The results obtained demonstrated the typical sulfated nature of acid mine drainage (AMD) and suggested the effectiveness of acidophilic algae as indicators of mining pollution. Mineralogical analysis by X-ray diffraction and transmission electron microscopy highlights the role of AMD-precipitates controlling the mobility of pollutants, in particular of arsenic.(undefined

O PRÉ-VESTIBULAR SOCIAL: DESAFIOS À BUSCA DA INCLUSÃO SOCIAL

O artigo analisa a contribuição do Programa Pré-Vestibular Social (PVS), inserido na Fundação Cecierj: Centro de Ciências e Educação Superior a Distância do Estado do Rio de Janeiro, no enfrentamento de algumas barreiras de acesso ao Ensino Superior nesse estado. Diversas expressões de exclusão/inclusão são utilizadas como fio condutor da análise, partindo-se do princípio de que o desenvolvimento de ações educativas complementares e as informações são fundamentais para favorecer o acesso de estudantes de baixa renda a instituições de Ensino Superior, em especial nas universidades públicas, que historicamente têm sido elitizadas, sobretudo nos bacharelados formadores de profissionais liberais. Para este estudo, foi feita uma revisão da literatura sobre o tema, especialmente sobre a questão da exclusão, bem como foram utilizadas matérias em jornais, sites da internet, dados estatísticos produzidos pelo PVS e por órgãos de pesquisa especializados. O  trabalho demonstra a relevância do programa e de seus resultados, embora aponte algumas alternativas para a sua expansão e melhoria tais como: a ampliação de polos em diferentes municípios e a melhoria da infraestrutura nos já existentes, o aperfeiçoamento de professores através da criação de estratégias/incentivos que garantam a qualidade do curso, a capacitação tanto de alunos como de professores na área de informática, a implementação da disciplina de língua estrangeira (inglês) com metodologia EAD, a ampliação do leque de alternativas culturais aos alunos e professores. Finalmente, destaca-se como desafio a inclusão de alunos de baixa renda, deficientes visuais e auditivos

New eugenol derivatives with enhanced insecticidal activity

Eugenol, the generic name of 4-allyl-2-methoxyphenol, is the major component of clove essential oil, and has demonstrated relevant biological potential with well-known antimicrobial and antioxidant actions. New O-alkylated eugenol derivatives, bearing a propyl chain with terminals like hydrogen, hydroxyl, ester, chlorine, and carboxylic acid, were synthesized in the present work. These compounds were later subjected to epoxidation conditions to give the corresponding oxiranes. All derivatives were evaluated against their effect upon the viability of insect cell line Sf9 (Spodoptera frugiperda), demonstrating that structural changes elicit marked effects in terms of potency. In addition, the most promising molecules were evaluated for their impact in cell morphology, caspase-like activity, and potential toxicity towards human cells. Some molecules stood out in terms of toxicity towards insect cells, with morphological assessment of treated cells showing chromatin condensation and fragmentation, which are compatible with the occurrence of programmed cell death, later confirmed by evaluation of caspase-like activity. These findings point out the potential use of eugenol derivatives as semisynthetic insecticides from plant natural products.This research was funded by COMPETE 2020 program, co-financed by the FEDER and the European Union, PTDC/ASP-AGR/30154/2017 (POCI-01-0145-FEDER-030154). The authors also acknowledge the Foundation for Science and Technology (FCT; Portugal), and FEDER-COMPETE/QREN-EU for financial support to the research centers CQ/UM (UIDB/00686/2020), CF-UM-UP (UIDB/04650/2020) and REQUIMTE (UIDB/50006/2020). The NMR spectrometer Bruker Avance III 400 is part of the NationalNMRNetwork and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005, with funds from POCI 2010 (FEDER) and the FCT. The authors would also like to thank RIAIDT-USC for the use of their analytical facilities

Suitability of PLLA as piezoelectric substrates for tissue engineering evidenced by microscopy techniques

Since the discovery of the piezoelectric character of bone, the suitability of some piezoelectric materials have been studied for bone repair; they are thought to act like transducers converting the mechanical energy of skeletal deformation in electrical stimuli capable of controlling osteogenic growth. The mechanisms underlying this process are far from being understood and systematic studies at a local scale are required. Atomic force microscopy (AFM) is a unique way to observe phenomena at the nanoscale and liquid imaging provides a unique tool to assess biological phenomena at the nanoscale. So in this study, aiming at a better understanding of the role of piezoelectricity in the osteogenic growth, the interaction between a poled piezoelectric material, in this case poly (L-lactic) acid and an adhesion promoting protein, the fibronectin, and bone-like cells is evaluated by scanning probe microscopy and confocal laser scanning microscopy (CLSM). © Microscopy Society of America 2012.(undefined