Revascularização pulpar em dentes imaturos

A revascularização pulpar é um tratamento de Medicina Dentária que tem por objetivo alcançar o desenvolvimento radicular em dentes imaturos necrosados, permitindo que as raízes dos dentes imaturos se desenvolvam apesar da inexistência de polpa. A necrose pulpar ocorre após cárie ou traumatismo dentário. Em pacientes menores é relativamente frequente encontrar dentes em que este tratamento é o mais indicado, uma vez que as paredes das raízes não estão totalmente formadas. O presente trabalho tem por objetivo geral compreender o proceso de revascularização pulpar em dentes imaturos. Realizou-se uma pesquisa bibliográfica nas bases de dados: Pubmed e ScienceDirect, entre 11 e 19 de Março de 2019. As estratégias de procura derivam da combinação das palabras-chave expostas e dos operadores booleanos AND e OR, recuperando um total de 2948 artigos, os quais foram reduzidos, pelos critérios de inclusão e exclusão utilizados, a 25 documentos finais que são expostos neste trabalho. Os resultados descritos mostram que os artigos consultados apresentam um alto grau de homogeneidade tanto na idade dos participantes (menores, geralmente entre 8 e 11 anos) como no tamanho da amostra dos dentes utilizados (geralmente um ou dois dentes tratados por paciente); além disso, existem várias estratégias de revascularização pulpar, entre elas TAP, Ca(OH)2 e CHP. Habitualmente, o meio auxiliar de diagnóstico e de monitorização mais utilizado é a radiografia, que permite a detecção objetiva da situação inicial e da evolução do dente após o tratamento. E este meio auxiliar de diagnóstico é apoiado por outros testes, como a percussão dentária ou testes térmicos. Os dados obtidos permitem observar uma redução do espaço entre polpa e o dente, fechamento apical, espessamento e alongamento radicular, aumento da densidade óssea, redução do tamanho da lesão desde o momento inicial e durante o seguimento do paciente. Pode concluir-se que a revascularização pulpar é um tratamento eficaz, no qual, a partir de três meses, podem ser detectadas melhorias radiográficas e na percepção do paciente com a redução da sensação dolorosa. É uma estratégia amplamente utilizada, com uma elevada taxa de sucesso durante a fase infantil em que este trabalho se centra

Integrating self-assembly and biofabrication for the development of structures with enhanced complexity and hierarchical control

Nature has evolved to grow and regenerate tissues and organs using self-assembling processes capable of organizing a wide variety of molecular building-blocks at multiple size scales. As the field of biofabrication progresses, it is essential to develop innovative ways that can enhance our capacity to build more complex macroscopic structures using molecular and nanoscale components in a rational manner. In this review, we highlight the emerging opportunities, advantages, and challenges of incorporating self-assembly with biofabrication for the development of more biologically relevant, active, and functional structures. The review is organized in four sections. First, to better appreciate the benefits of this integrated approach, we summarize recent advances in self-assembly and biofabrication aimed at improving hierarchical control. Then, we discuss work focused on combining self-assembly with biofabrication in three areas including a) conventional bioprinting techniques using self-assembling bioinks; b) new methods where self-assembly drives the fabrication process, and c) techniques based on cellular self-assembly. The ultimate goal of this review is to emphasize the importance of structural hierarchy in biological systems and to highlight the potential behind the integration of biofabrication and self-assembly towards the development of more functional structures for tissue engineering and regenerative medicine

Connective tissue progenitor cell growth characteristics on textured substrates

Growth characteristics of human connective tissue progenitor (CTP) cells were investigated on smooth and textured substrates, which were produced using MEMS (microelectromechanical systems) fabrication technology. Human bone marrow derived cells were cultured for 9 days under conditions promoting osteoblastic differentiation on polydimethylsiloxane (PDMS) substrates comprising smooth (non-patterned) surfaces (SMOOTH), 4 different cylindrical post micro-textures (POSTS) that were 7–10 μm high and 5, 10, 20, and 40 μm diameter, respectively, and channel micro-textures (CHANNELS) with curved cross-sections that were 11 μm high, 45 μm wide, and separated by 5 μm wide ridges. Standard glass-tissue culture surfaces were used as controls. Micro-textures resulted in the modification of CTP morphology, attachment, migration, and proliferation characteristics. Specifically, cells on POSTS exhibited more contoured morphology with closely packed cytoskeletal actin microfilaments compared to the more random orientation in cells grown on SMOOTH. CTP colonies on 10 μm-diameter POSTS exhibited higher cell number than any other POSTS, and a significant increase in cell number (442%) compared to colonies on SMOOTH (71%). On CHANNELS, colonies tended to be denser (229%) than on POSTS (up to 140% on 10 μm POSTS), and significantly more so compared to those on SMOOTH (104%)

Point of optimal kinematic error: Improvement of the instantaneous helical pivot method for locating centers of rotation

[EN] This paper proposes a variation of the instantaneous helical pivot technique for locating centers of rotation. The point of optimal kinematic error (POKE), which minimizes the velocity at the center of rotation, may be obtained by just adding a weighting factor equal to the square of angular velocity in Woltring's equation of the pivot of instantaneous helical axes (PIHA). Calculations are simplified with respect to the original method, since it is not necessary to make explicit calculations of the helical axis, and the effect of accidental errors is reduced. The improved performance of this method was validated by simulations based on a functional calibration task for the gleno-humeral joint center. Noisy data caused a systematic dislocation of the calculated center of rotation towards the center of the arm marker cluster. This error in PIHA could even exceed the effect of soft tissue artifacts associated to small and medium deformations, but it was successfully reduced by the POKE estimation.This work has been funded by the Spanish Government (Grants DPI2009-13830-C02-01, DPI2009-13830-CO2-02, DPI2010-20814-CO2-01, DPI2010-20814-CO2-02).De Rosario Martínez, H.; Page Del Pozo, AF.; Mata Amela, V. (2014). Point of optimal kinematic error: Improvement of the instantaneous helical pivot method for locating centers of rotation. Journal of Biomechanics. 47(7):1742-1747. doi:10.1016/j.jbiomech.2014.02.003S1742174747

Produtividade e desempenho exportador das firmas na indústria de transformação brasileira

O processo de abertura comercial trouxe mudanças importantes para a economia brasileira. As empresas melhoraram a produtividade a fim de se inserirem de forma competitiva no mercado internacional. Este trabalho analisou as diferenças de produtividade entre firmas exportadoras e firmas não exportadoras no Brasil. Utilizando o teste não paramétrico de Kolmogorov-Smirnov, comparam-se as distribuições de produtividade com dados ao nível de firmas. Os resultados encontrados mostram claramente maiores níveis de produtividade para as firmas exportadoras do que para as firmas não exportadoras. Ademais, as evidências encontradas mostram-se mais robustas para o grupo de firmas de pequeno porte vis-à-vis as firmas de grande porte. Quanto à explicação dessas diferenças, os resultados encontrados parecem dar suporte à hipótese de seleção, ou seja, o maior nível de produtividade das firmas exportadoras aparenta ser fruto de processos de seleção das firmas não apenas na entrada, mas também na saída do mercado de exportação. Por outro lado, os resultados encontrados não confirmam a existência de processos de aprendizado no mercado exportador brasileiro. Durante o período considerado, as diferenças entre as taxas de crescimento da produtividade das firmas exportadoras e das não exportadoras não foram significantes.The trade opening process made important adjustments in the Brazilian economy. Several firms enhanced their productivity in order to enter foreign market competitively. This paper analyzed the productivity differences between exporting and non-exporting firms in Brazil. Using the Kolmogorov-Smirnov nonparametric test, we compare productivity difference in firm-level data. The results reveal higher productivity levels in exporting firms compared to non-exporting ones. Besides, the findings are more robust to the group of smaller firms. Concerning the explanation of those differences, the results appear to support the hypothesis of selection, i.e., the reason for the higher productivity level of exporting firms seems due to selection processes not only accrued of entering foreign markets, but also of exiting them. On the other hand, the results do not confirm the existence of a learning process in the exporting market. During the period under analysis, the firms' productivity growth divergences were not significant

Comércio Intra-Indústria e Desigualdade de Rendimentos nas Firmas da Indústria Brasileira

Investiga-se os efeitos do comércio intra-industria sobre a desigualdade de rendimentos entre trabalhadores qualificados e menos qualificados para 22 segmentos da industria de transformação brasileira durante o período 1997 a 2002. A principal inovação diz respeito à utilização de dados desagregados ao nível de formas e ao cruzamento de informações das formas (exportação, importação, emprego, produtividade, marcas e patentes, investimento em tecnologia) com os dados dos trabalhadores vinculados. Observou-se que, independentemente do tamanho da forma e do nível de qualificação do trabalhador, formas exportadoras remuneram melhor seus trabalhadores do que as que não exportam. A comparação dos salários dos trabalhadores qualificados, bem como dos não qualificados, das formas exportadoras versus não exportadoras revela que as maiores discrepâncias encontram-se nas formas com até 99 funcionários. Os resultados sinalizam uma correlação positiva entre comércio intra-industria e desigualdades salariais no Brasil.Comércio Internacional, Intra-Industria, Desigualdades, Salários, Firmas

Post microtextures accelerate cell proliferation and osteogenesis

AbstractThe influence of surface microtexture on osteogenesis was investigated in vitro by examining the proliferation and differentiation characteristics of a class of adult stem cells and their progeny, collectively known as connective tissue progenitor cells (CTPs). Human bone marrow-derived CTPs were cultured for up to 60days on smooth polydimethylsiloxane (PDMS) surfaces and on PDMS with post microtextures that were 10μm in diameter and 6μm in height, with 10μm separation. DNA quantification revealed that the numbers of CTPs initially attached to both substrates were similar. However, cells on microtextured PDMS transitioned from lag phase after 4days of culture, in contrast to 6days for cells on smooth surfaces. By day 9 cells on the smooth surfaces exhibited arbitrary flattened shapes and migrated without any preferred orientation. In contrast, cells on the microtextured PDMS grew along the array of posts in an orthogonal manner. By days 30 and 60 cells grew and covered all surfaces with extracellular matrix. Western blot analysis revealed that the expression of integrin α5 was greater on the microtextured PDMS compared with smooth surfaces. Real time reverse transcription-polymerase chain reaction revealed that gene expression of alkaline phosphatase had decreased by days 30 and 60, compared with that on day 9, for both substrates. Gene expression of collagen I and osteocalcin was consistently greater on post microtextures relative to smooth surfaces at all time points

Model of Soft Tissue Artifact Propagation to Joint Angles in Human Movement Analysis

[EN] This work describes the kinematic laws that govern the transmission of soft tissue artifact errors to kinematic variables in the analysis of human movements. Artifacts are described as relative translations and rotations of the marker cluster over the bone, and a set of explicit expressions is defined to account for the effect of that relative motion on different representations of rotations: the rotation around the screw axis, or rotation vector, and three Euler angle sequences (XY0Z, YX0Y00, ZX0 Y00). Although the error transmission is nonlinear in all cases, the effect of artifacts is greater on Euler sequences than on the rotation vector. Specifically, there are crosstalk effects in Euler sequences that amplify the errors near singular configurations. This fact is an additional source of variability in studies that describe artifacts by comparing the Euler angles obtained from skin markers, with the angles of an artifact-free gold standard. The transmission of errors to rotation vector coordinates is less variable or dependent on the type of motion. This model has been tested in an experiment with a deformable mechanical model with a spherical joint.This work has been funded by the Spanish Government and co-financed by EU FEDER funds (Grants DPI2009-13830-C02-01 and DPI2009-13830-C02-02).Page Del Pozo, AF.; De Rosario Martínez, H.; Mata Amela, V.; Besa Gonzálvez, AJ. (2014). Model of Soft Tissue Artifact Propagation to Joint Angles in Human Movement Analysis. Journal of Biomechanical Engineering. 136:1-7. doi:10.1115/1.4026226S1713

Representation of planar motion of complex joints by means of rolling pairs. Application to neck motion

[EN] We propose to model planar movements between two human segments by means of rolling-without-slipping kinematic pairs. We compute the path traced by the instantaneous center of rotation (ICR) as seen from the proximal and distal segments, thus obtaining the fixed and moving centrodes, respectively. The joint motion is then represented by the rolling-without-slipping of one centrode on the other. The resulting joint kinematic model is based on the real movement and accounts for nonfixed axes of rotation; therefore it could improve current models based on revolute pairs in those cases where joint movement implies displacement of the ICR. Previous authors have used the ICR to characterize human joint motion, but they only considered the fixed centrode. Such an approach is not adequate for reproducing motion because the fixed centrode by itself does not convey information about body position. The combination of the fixed and moving centrodes gathers the kinematic information needed to reproduce the position and velocities of moving bodies. To illustrate our method, we applied it to the flexion-extension movement of the head relative to the thorax. The model provides a good estimation of motion both for position variables (mean R pos=0.995) and for velocities (mean R vel=0.958). This approach is more realistic than other models of neck motion based on revolute pairs, such as the dual-pivot model. The geometry of the centrodes can provide some information about the nature of the movement. For instance, the ascending and descending curves of the fixed centrode suggest a sequential movement of the cervical vertebrae. © 2010 Elsevier Ltd.This work was funded by the Spanish Government and co-financed by EU FEDER funds (Grants DPI2006-14722-C02-01, DPI2006-14722-C02-02, DPI2009-13830-C02-01, DPI2009-13830-C02-02 and Ramon y Cajal contract to JAG).Page Del Pozo, AF.; De Rosario Martínez, H.; Galvez Griso, JA.; Mata Amela, V. (2011). Representation of planar motion of complex joints by means of rolling pairs. Application to neck motion. Journal of Biomechanics. 44(4):747-750. https://doi.org/10.1016/j.jbiomech.2010.11.019S74775044

Elastin-Like Protein, with Statherin Derived Peptide, Controls Fluorapatite Formation and Morphology

Life Science Initiative, QMUL. The work was additionally supported by the European Research Council Starting Grant (STROFUNSCAFF) and the Marie Curie Career Integration Grant (BIOMORPH). The authors would like to acknowledge Dr. Carol Crean and Dr. Rachida Bance-Soualhi (Department of Chemistry, University of Surrey) for their help with acquiring the Raman spectroscopy data, funded by EPSRC (grant number EP/M022749/1). KS gratefully acknowledges Dr. Sherif El-Sharkawy for intellectual input and Gastón Agustín Primo for help with FTIR deconvolution, alongside other group members of the Mata, MHAtriCell and DPSU groups