Review of Piezoelectrical Materials Potentially Useful for Peripheral Nerve Repair

Funding Information: This research was funded by the International Atomic Energy Agency: Research Contract No. 24415 (CRP F23035). Authors acknowledge FCT—Fundação para a Ciência e a Tecnologia I.P. for the national funds in the scope of the project UIDB/04349/2020+UIDP/04349/2020, UIDB/00100/2020+LA/P/0056/2020 and UIDB/00329/2020. Publisher Copyright: © 2023 by the authors.It has increasingly been recognized that electrical currents play a pivotal role in cell migration and tissue repair, in a process named “galvanotaxis”. In this review, we summarize the current evidence supporting the potential benefits of electric stimulation (ES) in the physiology of peripheral nerve repair (PNR). Moreover, we discuss the potential of piezoelectric materials in this context. The use of these materials has deserved great attention, as the movement of the body or of the external environment can be used to power internally the electrical properties of devices used for providing ES or acting as sensory receptors in artificial skin (e-skin). The fact that organic materials sustain spontaneous degradation inside the body means their piezoelectric effect is limited in duration. In the case of PNR, this is not necessarily problematic, as ES is only required during the regeneration period. Arguably, piezoelectric materials have the potential to revolutionize PNR with new biomedical devices that range from scaffolds and nerve-guiding conduits to sensory or efferent components of e-skin. However, much remains to be learned regarding piezoelectric materials, their use in manufacturing of biomedical devices, and their sterilization process, to fine-tune their safe, effective, and predictable in vivo application.publishersversionpublishe

Friction Drag on a Particle Moving in a Nematic Liquid Crystal

The flow of a liquid crystal around a particle does not only depend on its shape and the viscosity coefficients but also on the direction of the molecules. We studied the resulting drag force on a sphere moving in a nematic liquid crystal (MBBA) in a low Reynold's number approach for a fixed director field (low Ericksen number regime) using the computational artificial compressibility method. Taking the necessary disclination loop around the sphere into account, the value of the drag force anisotropy (F_\perp/F_\parallel=1.50) for an exactly computed field is in good agreement with experiments (~1.5) done by conductivity diffusion measurements. We also present data for weak anchoring of the molecules on the particle surface and of trial fields, which show to be sufficiently good for most applications. Furthermore, the behaviour of the friction close to the transition point nematic isotropic and for a rod-like and a disc-like liquid crystal will be given.Comment: 23 pages RevTeX, including 3 PS figures, 1 PS table and 1 PS-LaTeX figure; Accepted for publication in Phys. Rev.

Fratura Proximal do Fémur Bilateral. Incidência e Fatores de Risco de Fratura Contralateral

Nos doentes com fratura osteoporótica da extremidade proximal do fémur, pouco é conhecido sobre a incidência e fatores de risco de fratura contralateral da extremidade proximal do fémur. O objetivo deste trabalho foi, através de um estudo retrospetivo determinar a incidência e os fatores de risco para fratura bilateral da extremidade proximal do fémur não contemporânea. Foram analisados os processos de 1911 doentes com fratura da extremidade proximal do fémur entre 2003 e 2009. Os dados recolhidos sobre as fraturas, tratamentos e comorbilidades foram trabalhados estatisticamente. Um total de 64 doentes (3,24%) teve fratura bilateral da extremidade proximal do fémur, com uma média de idades acima dos 80 anos. Determinou-se que existe uma relação direta entre o tipo da primeira e segunda fratura (intracapsular vs extraapsular), e que 70% das segundas fraturas ocorrem nos primeiros três anos após fratura. Das comorbilidades verificou-se que a doença de Parkinson, Hipertensão Arterial, doença Cardíaca, Anemia e alterações da Visão representam um risco acrescido para fratura contralateral da extremidade proximal do fémur. Propomos um follow-up mais rigoroso nos primeiros três anos após a primeira fratura e estabelecidas melhores formas de prevenção de fraturas e otimização das comorbilidades nos doentes com fatores de risco

Electrochemical Behavior and Determination of Fluconazole

The electrochemical behavior of fluconazole showed an irreversible oxidation process, with the electrochemical - chemical mechanism being highly dependent on the electrode material. Adsorption of reagent at positive applied potential was observed at Pt electrode while preferential adsorption of the oxidation products was observed at Glassy Carbon surfaces. In pH below 7.0, the anodic current process was intensively decreased. At carbon paste electrode, the fluconazole oxidation current, recorded in phosphate buffer solution (pH 8.0), changed linearly with the fluconazole concentration, Ipa = 5.7×10-5 (mA) × 0.052 [Fluconazol] (μg mL-1), in the range of 48.0 to 250.0 μg mL-1. The detection limit obtained was 6.3 μg mL-1.O comportamento eletroquímico do fluconazol demonstrou oxidação irreversível com mecanismos eletroquímicos-químicos dependentes do material eletródico. Em eletrodos de Pt observou-se adsorção do reagente sob a aplicação de potenciais positivos, enquanto adsorção preferencial dos produtos foi observada em eletrodo de carbono vítreo. Em valores de pH inferiores a 7,0, a corrente do processo anódico é intensamente diminuída. Em eletrodo de pasta de carbono e tampão fosfato, pH 8,0, a corrente de oxidação variou linearmente com a concentração de fluconazol em solução, Ipa = 5,7×10-5 (mA) × 0,052 [Fluconazol] (μg mL-1), no intervalo de 48,0 a 250,0 μg mL-1. O limite de detecção obtido foi 6,3 μg mL-1.FAPES

Juvenile Pompe Disease: Retrospective Clinical Study

ntrodução: A doença de Pompe ou glicogenose tipo II é uma doença autossómica recessiva por deficiência de maltase ácida. É uma entidade rara, com prevalência de 1/40.000 nas populações holandesa e afro-americana e 1/46000 na população australiana. Embora se distingam três formas de apresentação (infantil, juvenil e do adulto), observa-se um amplo espectro clínico. Em Portugal está disponível terapêutica enzimática de substituição desde 2006.Material e Métodos: Fez-se o estudo retrospetivo de quatro doentes (duas das quais irmãs), baseado na revisão dos processos clínicos.Resultados: Em todas, a doença manifestou-se no segundo ano de vida. O tempo até ao diagnóstico variou entre dois e onze anos. Aquando do diagnóstico, todas apresentavam miopatia com atraso de aquisições motoras e em duas havia hipertrofia miocárdica. A suspeita clínica surgiu por insuficiência respiratória em contexto infeccioso em duas doentes. Em todas havia elevação da creatina quinase e das aminotransferases. Todas evoluíram com insuficiência respiratória crónica por síndrome restritiva. O diagnóstico foi baseado na diminuição da atividade da maltase ácida em fibroblastos (0 a 1,5% do limite inferior do normal). Na biópsia muscular, realizada em três doentes, demonstrou-se acumulação lisossómica de glicogénio. Todas apresentavam a mutação c.1064T > C no exão 6 do gene GAA (glucosidase-alpha-acid), em homozigotia numa delas, associada às mutações c.1666A > G no exão 12 e c.2065G > A no exão 15 nas duas irmãs e à mutação c.380G > T no exão 2 na doente mais nova. Todas iniciaram terapia enzimática de substituiçãologo que disponível, com boa tolerância. A doente mais jovem faleceu pouco depois. As outras mantêm medidas de suporteventilatório e fisioterapia, deslocando-se a mais velha, em cadeira de rodas, mantendo a irmã marcha independente e necessitando a mais nova de andarilho.Conclusão: Os nossos casos incluem-se clinicamente na forma juvenil da doença de Pompe. A hipótese de doença de Pompe deve ser considerada em lactentes com miocardiopatia e nas miopatias progressivas, especialmente as das cinturas e dos músculos respiratórios em qualquer idade. A elevação da creatina quinase é um dado sensível, embora inespecífico. Dada a grande variabilidade dos achados genéticos, a demonstração da redução da atividade da maltase ácida continua a ser o pilar do diagnóstico

MARTA: A high-energy cosmic-ray detector concept with high-accuracy muon measurement

A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. The combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.Comment: 11 page

Growth factor-free vascularization of marine-origin collagen sponges using cryopreserved stromal vascular fractions from human adipose tissue

The successful integration of transplanted three-dimensional tissue engineering (TE) constructs depends greatly on their rapid vascularization. Therefore, it is essential to address this vascularization issue in the initial design of constructs for perfused tissues. Two of the most important variables in this regard are scaffold composition and cell sourcing. Collagens with marine origins overcome some issues associated with mammal-derived collagen while maintaining their advantages in terms of biocompatibility. Concurrently, the freshly isolated stromal vascular fraction (SVF) of adipose tissue has been proposed as an advantageous cell fraction for vascularization purposes due to its highly angiogenic properties, allowing extrinsic angiogenic growth factor-free vascularization strategies for TE applications. In this study, we aimed at understanding whether marine collagen 3D matrices could support cryopreserved human SVF in maintaining intrinsic angiogenic properties observed for fresh SVF. For this, cryopreserved human SVF was seeded on blue shark collagen sponges and cultured up to 7 days in a basal medium. The secretome profile of several angiogenesis-related factors was studied throughout culture times and correlated with the expression pattern of CD31 and CD146, which showed the formation of a prevascular network. Upon in ovo implantation, increased vessel recruitment was observed in prevascularized sponges when compared with sponges without SVF cells. Immunohistochemistry for CD31 demonstrated the improved integration of prevascularized sponges within chick chorioalantoic membrane (CAM) tissues, while in situ hybridization showed human cells lining blood vessels. These results demonstrate the potential of using cryopreserved SVF combined with marine collagen as a streamlined approach to improve the vascularization of TE constructs.This research has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 805411); Portuguese Foundation for Science and Technology under doctoral fellowship PD/BD/135252/2017 and individual grant IF/00347/2015; European Regional Development Fund, through INTERREG España-Portugal 2014-2020 under BLUEBIOLAB (0474_BLUEBIOLAB_1_E) project, through Atlantic Area Programme under BLUEHUMAN (EAPA_151/2016) project and through NORTE2020/PT2020 Programme under ATLANTIDA (Norte-01-0145-FEDER-000040) project

Compósitos de colagénio/apatite de origem marinha para aplicação em engenharia de tecidos mineralizados

Devido ao aumento de lesões associadas ao envelhecimento da população, a regeneração do tecido ósseo tem sido alvo de estudo. Apesar da vasta investigação neste sentido, os auto-enxertos continuam a prevalecer como tratamento de primeira linha, apesar das suas limitações. A extração de compostos de recursos marinhos para uso em abordagens de engenharia de tecidos emerge como uma alternativa promissora para regeneração de lesões ósseas. Neste capítulo apresenta-se um biomaterial promissor para aplicação em engenharia de tecidos duros tendo como base uma estratégia de valorização de sub-produtos marinhos, nomeadamente pele e dentes de tubarão.Os autores agradecem o apoio financeiro recebido da União Europeia através do Programa INTERREG—POCTEP, no âmbito dos Projetos 0687_NOVOMAR_1_P e 0245_IBEROS_1_E, através do Programa de cooperação transnacional Espaço Atlântico, no âmbito do Projeto MARMED (2011-1/164) e através do 7º Programa-Quadro de Investigação e Desenvolvimento Tecnológico (FP7), através do Projeto POLARIS (REGPOT-CT2012-316331). Os autores gostariam de agradecer também ao Centro Tecnológico del Mar (CETMAR, Vigo, Espanha) e COPEMAR SA (Espanha) pelo fornecimento dos subprodutos de tubarão. G.S.D agradece ao Programa Norte2020 (Portugal2020) pela bolsa de doutoramento (NORTE-08-5369-F SE-000044) e R.P. agradece à Fundação para a Ciência e a Tecnologia pelo contrato IF/00347/2015

Fine mapping seronegative and seropositive rheumatoid arthritis to shared and distinct HLA alleles by adjusting for the effects of heterogeneity

Despite progress in defining human leukocyte antigen (HLA) alleles for anti-citrullinated-protein-autoantibody-positive (ACPA(+)) rheumatoid arthritis (RA), identifying HLA alleles for ACPA-negative (ACPA(-)) RA has been challenging because of clinical heterogeneity within clinical cohorts. We imputed 8,961 classical HLA alleles, amino acids, and SNPs from Immunochip data in a discovery set of 2,406 ACPA(-) RA case and 13,930 control individuals. We developed a statistical approach to identify and adjust for clinical heterogeneity within ACPA(-) RA and observed independent associations for serine and leucine at position 11 in HLA-DRbeta1 (p = 1.4 x 10(-13), odds ratio [OR] = 1.30) and for aspartate at position 9 in HLA-B (p = 2.7 x 10(-12), OR = 1.39) within the peptide binding grooves. These amino acid positions induced associations at HLA-DRB1( *)03 (encoding serine at 11) and HLA-B( *)08 (encoding aspartate at 9). We validated these findings in an independent set of 427 ACPA(-) case subjects, carefully phenotyped with a highly sensitive ACPA assay, and 1,691 control subjects (HLA-DRbeta1 Ser11+Leu11: p = 5.8 x 10(-4), OR = 1.28; HLA-B Asp9: p = 2.6 x 10(-3), OR = 1.34). Although both amino acid sites drove risk of ACPA(+) and ACPA(-) disease, the effects of individual residues at HLA-DRbeta1 position 11 were distinct (p \u3c 2.9 x 10(-107)). We also identified an association with ACPA(+) RA at HLA-A position 77 (p = 2.7 x 10(-8), OR = 0.85) in 7,279 ACPA(+) RA case and 15,870 control subjects. These results contribute to mounting evidence that ACPA(+) and ACPA(-) RA are genetically distinct and potentially have separate autoantigens contributing to pathogenesis. We expect that our approach might have broad applications in analyzing clinical conditions with heterogeneity at both major histocompatibility complex (MHC) and non-MHC regions

From Uniaxial to Multiaxial Ultrasonic Fatigue Component Frequency Modulation and Experiment

Ultrasonic fatigue experiments demand meticulous monitoring, control, and precise measurement equipment, alongside rigorous design considerations for all present components. Ultrasonic fatigue testing (UTF) has continuously evolved towards proven methodology that is simpler, more reliable, and therefore standardizable. This study addresses the challenges and limitations inherent in UTF with regards to the specimen design and modulation. Analytical and computational methods prevalent in published research on specimen and ultrasonic component design are discussed. All discussed challenges are greatly enhanced when regarding multiaxial ultrasonic fatigue. Ultrasonic machine components and specimen setup must resonate at explicit high frequencies, exhibiting the desired mode shapes that induce targeted stresses. The interconnection between components, the desired frequency and associated mode shape, and the displacement-to-strain relationship are critical to successfully execute and monitor any ultrasonic fatigue experiment. Furthermore, this study dwells in a new proposed intricate semi-analytical formulation model for ultrasonic specimen geometries catered towards both uniaxial and multiaxial specimens. The significance of this work lies in its potential to empower researchers with a tool that enhances the design and execution of ultrasonic fatigue experiments. The proposed semianalytical method offers a more versatile and time-efficient approach for future exploration on optimization algorithms for ultrasonic fatigue components and specimens. To showcase its capabilities, all available and applied methods are revised and compared against the model analytically and then with experimental measurement results