New prospects in skin regeneration and repair using nanophased hydroxyapatite embedded in collagen nanofibers

This study reflects an exploitation of a composite matrix produced by electrospinning of collagen and electrospraying of nanophased hydroxyapatite (nanoHA), for skin regeneration applications. The main goal was to evaluate the effect of nanoHA, as source of localized calcium delivery, on human dermal fibroblasts, keratinocytes, and human mesenchymal stem cells (hMSCs) growth, proliferation, differentiation, and extracellular matrix production. This study revealed that calcium ions provided by nanoHA significantly enhanced cellular growth and proliferation rates and prevented adhesion of pathogenic bacteria strains typically found in human skin flora. Moreover, hMSCs were able to differentiate in both osteogenic and adipogenic lineages. Rat subcutaneous implantation of the membranes also revealed that no adverse reaction occurred. Therefore, the mechanically fit composite membrane presents a great potential to be used either as cell transplantation scaffold for skin wound regeneration or as wound dressing material in plastic surgery, burns treatment or skin diseases.info:eu-repo/semantics/acceptedVersio

Electrospun polycaprolactone (PCL) degradation: An in vitro and in vivo study

This work was supported by the Fundação para a Ciência e a Tecnologia (FCT) through the following projects: CDRSP: UIDB/04044/2020, UIDP/04044/2020 and MARE: UIDB/04292/2020 and UIDP/04292/2020. This study was also supported by PAMI-ROTEIRO/0328/2013 (No. 022158), MATIS (CENTRO-01-0145-FEDER-000014-3362), SpinningTNT (POCI-01-02B7-FEDER-069285), and the project LA/P/0069/2020 granted to the Associate Laboratory ARNET.Polycaprolactone (PCL) is widely used in tissue engineering due to its interesting properties, namely biocompatibility, biodegradability, elastic nature, availability, cost efficacy, and the approval of health authorities such as the American Food and Drug Administration (FDA). The PCL degradation rate is not the most adequate for specific applications such as skin regeneration due to the hydrophobic nature of bulk PCL. However, PCL electrospun fiber meshes, due to their low diameters resulting in high surface area, are expected to exhibit a fast degradation rate. In this work, in vitro and in vivo degradation studies were performed over 90 days to evaluate the potential of electrospun PCL as a wound dressing. Enzymatic and hydrolytic degradation studies in vitro, performed in a static medium, demonstrated the influence of lipase, which promoted a rate of degradation of 97% for PCL meshes. In an in vivo scenario, the degradation was slower, although the samples were not rejected, and were well-integrated in the surrounding tissues inside the subcutaneous pockets specifically created.info:eu-repo/semantics/publishedVersio

Bacterial cellulose-based microfluidic device for 3D skin modelling (skin-on-chip)

Paper fluidics is based on patterning hydrophilic paper with channels bounded by hydrophobic barriers. Fluids move along channels by capillarity. Several methods are available for patterning paper, with different costs/resolutions. Paper patterning for microfluidics also used the embossing technique to design open-channel microfluidic devices, fabricated by compressing the sheet of paper with the help of 3D plastic printing moulds. These approaches are adopted in this work to develop a multiwell-microplate paper-based microfluidic, aiming the creation of organs-on-chip, combining complexity and miniaturization. Bacterial Cellulose (BC) represents a source of highly pure and biocompatible cellulose, with huge technological potential in many fields - biomedical, composites, textiles, food and cosmetics textiles - but currently still rather underexploited [Gama et al, 2916; Klemm et al, 2018]. This work describes a novel approach towards the development of a nanostructured and multifunctional cellulose-based device for the continuous culture of animal cells and tissues. A multilayered system of modified BC (hydrophobized and electroconductive) was used to assemble the skin-on-chip, a microfluidic platform, using the lab-on-paper technology intended to mimic vascularization, with controlled flow, to introduce external stimuli, such as electrical or mechanical, and to support multicellular growth. This chip serves a multifactorial purpose, aiming the control of each part that make up the overall complex 3D system, including dynamic control of physical, chemical and gaseous gradients, ensure mimetic vascularization, introduce favourable stimuli and co-culture of skin cells. This model sustains cell growth and allow real time and in a high throughput manner to assess cellular phenomena, such as cell-cell crosstalk, paracrine factor exchange, ECM production, as well as tissue homeostasis in the presence of chemical, mechanical, electrical and biological stimuli, and also kinetics of substance delivery on/through the skin. BC hydrophobization was achieved using a new strategy for the surface modification of BC through the combination of oxygen plasma deposition and silanization with trichloromethyl silane. The combined use of the two techniques modifies both the surface roughness and energy and therefore maximizes the hydrophobic effect obtained. These modified membranes were characterized by SEM, water contact angle measurements, FTIR-ATR and XPS, and its cytotoxic potential was investigated using both indirect and direct contact studies with cells. Importantly, this surface modification revealed no short-term cytotoxic effects on L929 and hDNFs cells. This material was used for the construction of a BC-based well plate for cell culture, which can be supplied continuously with culture medium in long term studies (ranging from days to weeks), using a two-layered 3D full-thickness skin equivalent consisting of an epidermal and a dermal tissue layer, cultivated in alginate scaffolds, that can be maintained and studied as a skin surrogate on the SkinChip [Maia et al, 2014].info:eu-repo/semantics/publishedVersio

Correction: Biofunctionalized pectin hydrogels as 3D cellular microenvironments

Correction for 'Biofunctionalized pectin hydrogels as 3D cellular microenvironments' by Sara C. Neves et al., J. Mater. Chem. B, 2015, 3, 2096–2108

Hydrophobic modification of bacterial cellulose using oxygen plasma treatment and chemical vapor deposition

A new strategy for the surface modification of bacterial cellulose (BC) through the combination of oxygen plasma deposition and silanization with trichloromethyl silane (TCMS) is described. The combined use of the two techniques modifies both the surface roughness and energy and therefore maximizes the obtained hydrophobic effect. These modified membranes were characterized by Scanning Electron Microscopy (SEM), water contact angle measurements, Fourier-transform infrared spectroscopy (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS), and its cytotoxic potential was investigated using both indirect and direct contact in vitro studies. The obtained results suggest an effective conjugation of TCMS to the surface of BC, leading to a highly hydrophobic surface, with a water contact angle of approximately 130º. It is also demonstrated that this is a stable and durable surface modification strategy, since BC remained hydrophobic even after 6 months, in dry conditions or after being submerged in distilled water for about a month. Importantly, this surface modification revealed no short-term cytotoxic effects on L929 and hDNFs cells. Altogether, these data indicate the successful development of a surface modification method that can be applied to BC, enabling the production of a biodegradable and hydrophobic platform that can be applied to different areas of research and industry.This work was supported by the Fundação para a Ciência e a Tecnologia (FCT), under the project ‘‘SkinChip: Disruptive cellulose-based microfluidic device for 3D skin modelling’’ (PTDC/BBB-BIO/1889/2014, SFRH/BPD/121526/2016), co-financed by the Lisboa 2020, COMPETE 2020, Portugal 2020 and the BioTecNorte operation (NORTE01-0145-FEDER-000004) with funding by the European Regional Development Fund under the scope of Norte2020— Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Antimicrobial properties of gallium (III)-and iron (III)-loaded polysaccharides affecting the growth of escherichia coli, staphylococcus aureus, and pseudomonas aeruginosa, in vitro

Antimicrobial resistance (AMR) has become a global concern as many bacterial species have developed resistance to commonly prescribed antibiotics, making them ineffective to treatments. One type of antibiotics, gallium(III) compounds, stands out as possible candidates due to their unique “Trojan horse” mechanism to tackle bacterial growth, by substituting iron(III) in the metabolic cycles of bacteria. In this study, we tested three polysaccharides (carboxymethyl cellulose (CMC), alginate, and pectin) as the binding and delivery agent for gallium on three bacteria (Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus) with a potential bioresponsive delivery mode. Two types of analysis on bacterial growth (minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC)) were carried out while iron(III)-loaded polysaccharide samples were also tested for comparison. The results suggested that gallium showed an improved inhibitory activity on bacterial growth, in particular gallium(III)-loaded carboxymethyl cellulose (Ga-CMC) sample showing an inhibiting effect on growth for all three tested bacteria. At the MIC for all three bacteria, Ga-CMC showed no cytotoxicity effect on human dermal neonatal fibroblasts (HDNF). Therefore, these bioresponsive gallium(III) polysaccharide compounds show significant potential to be developed as the next-generation antibacterial agents with controlled release capability.info:eu-repo/semantics/acceptedVersio

Limitações e formação docente para abordar a temática circense nas aulas de educação física

Introdução: As manifestações circenses nas aulas de educação física são uma necessidade contemporânea. Contudo, algumas limitações são apontadas por professores(as) que atuam na educação básica, evidenciando sua interface com a formação inicial e continuada. Objetivo: Analisar as possíveis limitações docente para o desenvolvimento da tematização das atividades circenses nas aulas de Educação Física do ensino fundamental, bem como evidenciar aspectos associados ao processo de formação. Métodos: Foi realizada uma pesquisa qualitativa entre oito professores(as) atuantes no ensino fundamental em escolas públicas da cidade de Mauá (SP), com caráter descritivo e explicativo, utilizando a técnica de análise de conteúdo. Resultados: Foi verificado que as limitações físicas, materiais e técnicas são apontadas pelos(as) docentes como aspectos determinantes para não abordagem do tema em suas aulas. Demonstram limitações em relação a concepções teóricas evidenciando a necessidade de uma formação mais sólida e contextualizada ainda na formação inicial de professores(as) assim como na formação continuada. Conclusão: Os professores (as) apresentam inúmeras limitações quanto ao trato pedagógico e estas se associam à formação inicial e continuada. ABSTRACT. Limitations and teacher training to approach the circus theme in physical education classes  Background: Circus manifestations in physical education classes are a contemporary obligation. However, some issues are pointed out by teachers who work with basic education, evidenced by their interface with an initial and continuous educational development. Objective: To analyze the possibilities of teachers for the thematic circus activities in Physical Education classes. Methods: A qualitative research was carried out by eight teachers working in elementary education in public schools in the city of Mauá (São Paulo, Brazil), with descriptive and explanatory approach, using a content analysis technique. Results: It was possible to notice that the physical, material and technical constraints are pointed out by the teachers as determinant aspects for the non-approach of the theme in their classes. They demonstrate limitations in relation to theoretical conceptions, evidencing the need for a more solid and contextualized training in the initial formation of teachers as well as in continuous education. Conclusion: Teachers have many limitations on pedagogical treatment and these are associated with initial and continuous education

γ-Tubulin ring complexes regulate microtubule plus end dynamics

Independently of their nucleation activity, γ-tubulin ring complex proteins localize along microtubules, limiting catastrophe events during interphase

A study on the effects of using ECN on the performance of Diffserv networks

This dissertation presents a study that evaluates the performance of an architecture that aggregates the Differentiated Service (DiffServ) model and the Explicit Congestion Notifícation (ECN) mechanism. These technologies represent two key elements for Quality of Service (QoS), which are: Service differentiation and traffic management. A series of simulations were implemented, not only for the proposed model, but also for the traditional one, and the obtained results were compared in order to identify the solution that offers better performance and QoS. The parameters analyzed were link effíciency, fairness of bandwidth sharing and packet discard, timeout and retransmission rates. Issues that affect the Service levei have also been assessed like: number of active flows, link congestion levei, interaction with non responsive sources, flows with distinct RTTs, variation in packet size, number of flows in an aggregate, size of target rate and interaction with varied congestion control algorithms. The simulations results indicate that the use of ECN optimizes DiffServ performance for a great variety of scenarios. In particular, when the network is correctly dimensioned, the use of ECN, not only provides performance benefits, but also optimizes bandwidth sharing and minimizes the effects of most factors that affect the Service levei provided to sources with distinct characteristics. This behavior is even more evident when the total reserved bandwidth approaches the total link capacity, but it is reversed when the network is underprovisioned. This demonstrates that, to make full usage of the benefits of the DiffServ and ECN combination, it is essential to avoid that the total contracted bandwidth be superior to the link capacity.Dissertação (Mestrado)Nesta dissertação é apresentado um estudo que avalia o desempenho de um ambiente de rede IP que integre a arquitetura de Serviços Diferenciados (DifíServ) e o mecanismo de Notificação Explícita de Congestionamento (ECN). Estas tecnologias representam dois elementos chave na obtenção de Qualidade de Serviço (QoS), são eles: a diferenciação de serviços e o gerenciamento de tráfego. Foram realizadas simulações que contemplam tanto o modelo que implementa ECN quanto o modelo atualmente utilizado. A análise dos resultados obtidos permitiu a elaboração de um estudo comparativo de desempenho entre estes dois modelos. Foram avaliados a eficiência do enlace, a justiça no compartilhamento de largura de banda e as taxas de descarte, timeout e retransmissão de pacotes. Também foram abordadas questões como: quantidade de fluxos ativos, dimensionamento da rede, interação com fontes não cooperantes, fluxos com RTTs distintos, tamanhos de pacote variados, agregação de fluxos, fontes com diferentes larguras de banda contratadas e interação com algoritmos de controle de congestionamento diversos. Os resultados obtidos indicaram que o uso do ECN otimiza o desempenho do DifíServ nos mais variados cenários. Em especial, quando a rede é corretamente dimensionada, o uso do ECN, além de prover ganhos de desempenho, otimiza o compartilhamento de largura de banda e ameniza os efeitos da maioria dos fatores que influenciam o nível de serviço oferecido à fontes com características distintas. Este comportamento é ainda mais evidenciado quando o total de reserva de largura de banda se aproxima da capacidade total de transmissão, mas se inverte quando a rede está mal dimensionada. Isto demonstra que, para se usufruir dos benefícios do uso combinado da arquitetura DifíServ e do mecanismo ECN, é necessário prevenir que a largura de banda contratada seja maior que a capacidade de transmissão

A single-component hydrogel bioink for bioprinting of bioengineered 3D constructs for dermal tissue engineering

This work was supported by the project Norte-01-0145-FEDER- 000012 – Structured program on bioengineered therapies for infectious diseases and tissue regeneration, supported by the Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), and supported by the project P2020-PTDC/BBB ECT/2145/2014 funded by POCI via FEDER and by Foundation for Science and Technology (FCT) via OE. R. P., A. S. and C. B. thank FCT for the doctoral grant SFRH/ BD/91151/2012, the post-doctoral grant SFRH/BPD/90047/2012 and the FCT Investigator research position IF/00296/2015 (FCT and POPH/ESF), respectively. The authors thank D. S. and M. A. from CEMUP (Centro de Materiais da Universidade do Porto) for the CryoSEM and 1H NMR analyses, respectively.Bioprinting is attractive to create cellularized constructs for skin repair. However, the vast majority of bioinks present limitations in the printing of chemically defined 3D constructs with controllable biophysical and biochemical properties. To address this challenge, a single-component hydrogel bioink with a controlled density of cell-adhesive ligands, tuneable mechanical properties and adjustable rheological behaviour is developed for extrusion bioprinting and applied for the biofabrication of 3D dermal constructs. A methacrylate modified pectin bioink is designed to allow the tethering of integrin-binding motifs and the formation of hydrogels by UV photopolymerization and ionic gelation. The rheological behaviour of a low polymer concentration (1.5 wt%) solution is adjusted by ionic crosslinking, yielding a printable bioink that holds the predesigned shape upon deposition for postprinting photocrosslinking. Printed constructs provide a suitablemicroenvironment that supports the deposition of endogenous extracellular matrix, rich in collagen and fibronectin, by entrapped dermal fibroblasts. This approach enables the design of chemically defined and cell-responsive bioinks for tissue engineering applications and particularly for the generation of biomimetic skin constructs.info:eu-repo/semantics/publishedVersio