Horizontal transfer of exosomal microRNAs transduce apoptotic signals between pancreatic beta-cells.

BACKGROUND: Diabetes mellitus is a common metabolic disorder characterized by dysfunction of insulin-secreting pancreatic beta-cells. MicroRNAs are important regulators of beta-cell activities. These non-coding RNAs have recently been discovered to exert their effects not only inside the cell producing them but, upon exosome-mediated transfer, also in other recipient cells. This novel communication mode remains unexplored in pancreatic beta-cells. In the present study, the microRNA content of exosomes released by beta-cells in physiological and physiopathological conditions was analyzed and the biological impact of their transfer to recipient cells investigated. RESULTS: Exosomes were isolated from the culture media of MIN6B1 and INS-1 derived 832/13 beta-cell lines and from mice, rat or human islets. Global profiling revealed that the microRNAs released in MIN6B1 exosomes do not simply reflect the content of the cells of origin. Indeed, while a subset of microRNAs was preferentially released in exosomes others were selectively retained in the cells. Moreover, exposure of MIN6B1 cells to inflammatory cytokines changed the release of several microRNAs. The dynamics of microRNA secretion and their potential transfer to recipient cells were next investigated. As a proof-of-concept, we demonstrate that if cel-miR-238, a C. Elegans microRNA not present in mammalian cells, is expressed in MIN6B1 cells a fraction of it is released in exosomes and is transferred to recipient beta-cells. Furthermore, incubation of untreated MIN6B1 or mice islet cells in the presence of microRNA-containing exosomes isolated from the culture media of cytokine-treated MIN6B1 cells triggers apoptosis of recipient cells. In contrast, exosomes originating from cells not exposed to cytokines have no impact on cell survival. Apoptosis induced by exosomes produced by cytokine-treated cells was prevented by down-regulation of the microRNA-mediating silencing protein Ago2 in recipient cells, suggesting that the effect is mediated by the non-coding RNAs. CONCLUSIONS: Taken together, our results suggest that beta-cells secrete microRNAs that can be transferred to neighboring beta-cells. Exposure of donor cells to pathophysiological conditions commonly associated with diabetes modifies the release of microRNAs and affects survival of recipient beta-cells. Our results support the concept that exosomal microRNAs transfer constitutes a novel cell-to-cell communication mechanism regulating the activity of pancreatic beta-cells.

Articulação temporomandibular - aspectos normais e deslocamentos de disco: imagem por ressonância magnética

O deslocamento de disco da articulação temporomandibular tem sido definido como uma relação anormal do disco articular com o côndilo mandibular, fossa e eminência articulares. Os deslocamentos de disco podem estar presentes sem interferir com a função articular a curto prazo. A ressonância magnética tem sido o exame de imagem de primeira escolha para o diagnóstico das anormalidades de tecido mole da articulação temporomandibular, uma vez que apresenta alta acurácia na determinação da posição do disco articular. O objetivo deste trabalho é apresentar uma revisão de literatura, demonstrando os aspectos normais e os diferentes tipos de deslocamentos de disco desta articulação e o seu diagnóstico por imagem, destacando o papel do exame por ressonância magnética.

Migration and horizontal gene transfer divide microbial genomes into multiple niches.

Horizontal gene transfer is central to microbial evolution, because it enables genetic regions to spread horizontally through diverse communities. However, how gene transfer exerts such a strong effect is not understood. Here we develop an eco-evolutionary model and show how genetic transfer, even when rare, can transform the evolution and ecology of microbes. We recapitulate existing models, which suggest that asexual reproduction will overpower horizontal transfer and greatly limit its effects. We then show that allowing immigration completely changes these predictions. With migration, the rates and impacts of horizontal transfer are greatly increased, and transfer is most frequent for loci under positive natural selection. Our analysis explains how ecologically important loci can sweep through competing strains and species. In this way, microbial genomes can evolve to become ecologically diverse where different genomic regions encode for partially overlapping, but distinct, ecologies. Under these conditions ecological species do not exist, because genes, not species, inhabit niches.

Innovation and horizontal mergers in a vertically related industry

This paper analyzes the effects of horizontal mergers on innovation and consumer welfare in a vertically related industry context, in which downstream firms compete for customers with a differentiated final good and can undertake R&D activities to reduce their unit costs. Upstream and downstream horizontal mergers can take place. The results suggest that competition authorities aiming to promote innovation and consumer welfare should treat upstream and downstream mergers differently, since horizontal mergers between upstream firms are detrimental to innovation and consumer welfare. By contrast, policy makers should evaluate the market characteristics under downstream integration. We show that downstream horizontal mergers can be both innovation and consumer welfare enhancing in the short run, when the markets are sufficiently small. Keywords: Horizontal Mergers. Innovation. Vertical Relations. JEL Classification Numbers: L22, L41, O32

Correcting Interdevice Bias of Horizontal White-to-White and Sulcus-to-Sulcus Measures Used for Implantable Collamer Lens Sizing.

PURPOSE: To assess the agreement and repeatability of horizontal white-to-white (WTW) and horizontal sulcus-to-sulcus (STS) diameter measurements and use these data in combination with available literature to correct for interdevice bias in preoperative implantable collamer lens (ICL) size selection. DESIGN: Interinstrument reliability and bias assessment study. METHODS: A total of 107 eyes from 56 patients assessed for ICL implantation at our institution were included in the study. This was a consecutive series of all patients with suitable available data. The agreement and bias between WTW (measured with the Pentacam and BioGraph devices) and STS (measured with the HiScan device) were estimated. RESULTS: The mean spherical equivalent was -8.93 ± 5.69 diopters. The BioGraph measures of WTW were wider than those taken with the Pentacam (bias = 0.26 mm, P < .01), and both horizontal WTW measures were wider than the horizontal STS measures (bias >0.91 mm, P < .01). The repeatability (Sr) of STS measured with the HiScan was 0.39 mm, which was significantly reduced (Sr = 0.15 mm) when the average of 2 measures was used. Agreement between the horizontal WTW measures and horizontal STS estimates when bias was accounted for was г = 0.54 with the Pentacam and г = 0.64 with the BioGraph. CONCLUSIONS: Large interdevice bias was observed for WTW and STS measures. STS measures demonstrated poor repeatability, but the average of repeated measures significantly improved repeatability. In order to conform to the US Food and Drug Administration's accepted guidelines for ICL sizing, clinicians should be aware of and account for the inconsistencies between devices.

Emprego de nebulizador pneumático de ICP-MS como câmara de diluição em sistemas de injeção em fluxo para determinações multielementares

An automatic dispenser based on a flow-injection system used to introduce sample and analytical solution into an inductively coupled plasma mass spectrometer through a spray chamber is proposed. Analytical curves were constructed after the injection of 20 to 750 µL aliquots of a multielement standard solution (20.0 µg L-1 in Li, Be, Al, V, Cr, Mn, Ni, Co, Cu, Zn, As, Se, Sr, Ag, Cd, Ba, Tl, Pb) and the acquisition of the integrated transient signals. The linear concentration range could be extended to ca. five decades. The performance of the system was checked by analyzing a NIST 1643d reference material. Accuracy could be improved by the proper selection of the injected volume. Besides good precision (r.s.d. < 2%), the results obtained with the proposed procedure were closer to the certified values of the reference material than those obtained by direct aspiration or by injecting 125 µL of several analytical solutions and samples.

Propulsor pneumático versátil e isento de pulsação para sistemas de análise em fluxo

Aquarium air pumps are proposed and evaluated as pneumatic liquid propulsion devices for flow injection and continuos flow analysis (FIA and CFA) systems. This kind of pump is widely available at a very low cost and it can sustain a pressure around of 4 psi (0.28 bar) indefinitely. By applying this air pressure onto a solution contained in a reservoir flask, it is possible to reach flow rates of up to 12.5 mL min-1 for circuits comprising reactors, made from 0.8 i.d. tubing with a length of 100 cm. The precise adjustment of flow rate below the maximum one can be made with a simplified needle valve or inserting in series a short length of capillary tube. The absence of flow pulsation is a definite advantage in comparison with peristaltic pumps, especially when amperometric detection is elected, as confirmed experimentally in FIA and CF applications.

Horizontal Grid Size Selection and its Influence on Mesoscale Model Simulations

The use of two-dimensional spectral analysis applied to terrain heights in order to determine characteristic terrain spatial scales and its subsequent use for the objective definition of an adequate grid size required to resolve terrain forcing are presented in this paper. In order to illustrate the influence of grid size, atmospheric flow in a complex terrain area of the Spanish east coast is simulated by the Regional Atmospheric Modeling System (RAMS) mesoscale numerical model using different horizontal grid resolutions. In this area, a grid size of 2 km is required to account for 95% of terrain variance. Comparison among results of the different simulations shows that, although the main wind behavior does not change dramatically, some small-scale features appear when using a resolution of 2 km or finer. Horizontal flow pattern differences are significant both in the nighttime, when terrain forcing is more relevant, and in the daytime, when thermal forcing is dominant. Vertical structures also are investigated, and results show that vertical advection is influenced highly by the horizontal grid size during the daytime period. The turbulent kinetic energy and potential temperature vertical cross sections show substantial differences in the structure of the planetary boundary layer for each model configuration

Degradação de corantes ácidos por processos oxidativos avançados usando um reator com disco rotatório de baixa velocidade

Three technologies were tested (TiO2/UV, H2O2/UV, and TiO2/H2O2/UV) for the degradation and color removal of a 25 mg L-1 mixture of three acid dyes: Blue 9, Red 18, and Yellow 23. A low speed rotating disc reactor (20 rpm) and a H2O2 concentration of 2.5 mmol L-1 were used. The dyes did not significantly undergo photolysis, although they were all degraded by the studied advanced oxidation processes. With the TiO2/H2O2/UV process, a strong synergism was observed (color removal reached 100%). Pseudo first order kinetic constants were estimated for all processes, as well as the respective apparent photonic efficiencies.

Dispersão vertical e horizontal de conídios de Stenocarpella macrospora e Stenocarpella maydis

Em experimentos conduzidos no campo, quantificaram-se a dispersão vertical e horizontal dos conídios de Stenocarpella maydis e S. macrospora liberados de palha de milho (Zea mays) naturalmente infetada. Verificou-se que 93% do número total de conídios de S. maydis e 88% de S. macrospora foram capturados durante o dia, diferindo estatisticamente do período noturno. O número de conídios de S. maydis e S. macrospora capturados no ar foi inversamente proporcional à distância da posição vertical e horizontal das armadilhas da fonte de inóculo. Os conídios foram capturados até uma altura de 2 m acima e distantes 120 m da fonte de inóculo. No entanto, em ambos experimentos, a freqüência e o número de esporos coletados foram maiores até 25 cm acima e 20 m distante da fonte de inóculo. Além disto, a dispersão dos conídios isolados ou agrupados no cirro, ocorreu livremente no ar, não necessitando estarem veiculados a gotículas d'água.

Florística e estrutura horizontal da vegetação arbórea de uma ravina em um fragmento florestal no município de Viçosa, MG

Este estudo foi desenvolvido em um trecho de um fragmento de Floresta Estacional Semidecídua Montana, no Sítio Bom Sucesso, em Viçosa, MG. O objetivo deste trabalho foi conhecer a composição florística e a estrutura fitossociológica do componente arbóreo. Foram instalados 10 transectos de 50 x 10 m, subdivididos em cinco parcelas de 10 x 10 m cada um, totalizando 50 parcelas em 5.000 m². Foram incluídos na amostragem todos os indivíduos arbóreos que apresentavam, no mínimo, 15 cm de circunferência do tronco, a 130 cm do solo. Foram identificadas 151 espécies pertencentes a 108 gêneros de 45 famílias botânicas e amostrados, em 0,5 ha, 820 indivíduos arbóreos vivos e 32 mortos em pé, o que significou uma densidade total estimada de 1.704 indivíduos/ha. A área basal/ha foi de 38,450 m² e a altura média, de 8,43 m. Euterpe edulis foi o destaque da estrutura da vegetação estudada, com 314 indivíduos amostrados, resultando numa densidade relativa de 37,38%, freqüência absoluta de 90%, freqüência relativa de 8,91%, e dominância relativa de 18,79%. O índice de diversidade de Shannon foi de 3,52 e a eqüabilidade, igual a 0,696. Os resultados da composição florística e da estrutura fitossociológica indicaram alta riqueza e diversidade média, sendo a maior parte das espécies representada por poucos indivíduos.

Estrutura horizontal e vertical do componente arbóreo em fase de regeneração natural na mata Santa Luzia, no município de Catende-PE

O estudo foi desenvolvido no fragmento denominado Mata Santa Luzia, situado no Município de Catende, PE, nas coordenadas 8º72'49" S e 35º72'47" W, altitude de 239 m, com os objetivos de avaliar a regeneração natural total de espécies arbóreas no fragmento florestal e verificar a diversidade e estrutura das espécies nessa área. Para a estimativa da regeneração natural das espécies arbóreas no fragmento, foram locadas de forma sistemática 15 subparcelas permanentes de 25 m² (5 x 5 m), equidistantes em 50 m. O nível de inclusão adotado foi de CAP < 15 cm e as medições de altura (h), divididas em três classes, em que a classe 1 contemplou indivíduos com 1,0 < h < 2,0 m, a classe 2 com indivíduos 2,0 < h < 3,0 m e a classe 3 com indivíduos com h > 3,0 m. No fragmento foram amostrados 107 indivíduos vivos, pertencentes a 25 famílias botânicas e 36 táxons. Dessas, 33 foram identificadas em nível de espécie, duas em nível de gênero e uma se apresentou como indeterminada. As cinco espécies com maiores valores para regeneração natural total (RNT) foram assim distribuídas: Rheedia gardneriana Planch. & Triana (9,9%), Cupania racemosa (Vell.) Radlk (7,7%), Brosimum discolor Schott (7,4%), Vismia guianensis (Aubl.) Pers. (6,1%) e Protium heptaphyllum (Aubl.) Marchand (5,9%). Provavelmente, essas espécies no futuro serão as principais responsáveis pela manutenção da estrutura e fisionomia da floresta.

Aplicação de agrotóxicos em eucalipto utilizando pulverizador pneumático

O trabalho foi desenvolvido visando avaliar os parâmetros da pulverização em culturas arbóreas. A eficiência e a deposição de gotas sobre o alvo são importantes para elevar a rentabilidade na produção de madeira, diminuindo os riscos ambientais, e para a saúde do aplicador, aumentando a eficácia no combate de pragas e doenças. O objetivo deste trabalho foi avaliar os parâmetros operacionais de um pulverizador pneumático para aplicação em florestas adultas de eucalipto, através do estudo da densidade de gotas, da porcentagem de cobertura, do diâmetro da mediana volumétrica, do coeficiente de homogeneidade, da amplitude relativa e da uniformidade de distribuição volumétrica da calda. O pulverizador utilizado mostrou-se eficiente para a aplicação de agrotóxicos em árvores adultas de eucalipto. Observou-se que todos os tratamentos avaliados apresentaram densidade e tamanho de gotas satisfatórias para a pulverização. Quanto aos parâmetros porcentagem de cobertura, deposição e uniformidade de distribuição volumétrica, os melhores resultados ocorreram quando foram utilizados os índices volumétricos de 27 e 20,2 mL m³ de dossel. O índice volumétrico de 20,2 mL m³ de dossel foi o indicado para pulverização.

Efficiency of pneumatic and horizontal perforated disk meter mechanism in corn no-tillage seeders in soil with different mobilization reports

This work objectified to evaluate the efficiency of two meter mechanism of corn seeds when submitted to different forward speed and soil management system during the non-tillage seeding. It was used a factorial design in randomized blocks. The factors whose effects were examined were related to the seeders with pneumatic and horizontal disk meter mechanisms for the distribution of the seeds, to the set tractor-seeder forward speeds (4.4; 8.0 and 9.8 km h-1), and to the soil management system considering the corn no-tillage seeding over minimum tillage with chisel plow and the no-tillage system for the seeding of oat culture (Avena strigosa Schreb). It was verified that the forward speed didn't influence the initial and final stands of plants but it interfered in the regularity of longitudinal distribution of plants. The smallest speed provided the largest percentile of normal spacing between plants. The pneumatic meter mechanism presented better performance than the horizontal disk perforated in the longitudinal distribution of plants. About corn productivity aspect it's indifferent the recommendation of use for pneumatic and perforated horizontal disk meter mechanism of seeds.

Desempenho e características construtivas de um protótipo de dosador pneumático para sementes de arroz

Tendo em vista a elevação do custo das sementes miúdas e a inadequação das semeadoras de precisão atuais, que não semeiam culturas com pequenos espaçamentos entre linhas, o presente trabalho teve o objetivo de apresentar os resultados dos testes de um protótipo de dosador pneumático, tipo cilindro vertical, para sementes de arroz. Foram avaliadas em laboratório a precisão na captação de sementes (com pressões de -56,0; -62,7 e -73,1 kPa, velocidades tangenciais de 0,10; 0,22 e 0,30 m s-1, e orifícios dosadores de 1,2 e 1,5 mm), a regularidade de distribuição longitudinal de sementes (com o reservatório de sementes com 25 e 50% da capacidade, inclinação lateral de 0 e 11º, orifícios com 1,5 mm) e o dano mecânico de sementes, em experimentos inteiramente casualizados. As médias dos tratamentos foram comparadas por meio de análise de variância. Concluiu-se que os melhores resultados na captura foram obtidos na menor velocidade e com o menor nível de pressão, independentemente do tamanho do orifício. A percentagem de capturas simples chegou, em média, a 68,4%, com orifício de 1,5 mm. A precisão de dosagem alcançada na saída do tubo condutor foi de 37,6% de tempos de aceitáveis. O nível de sementes no reservatório e a inclinação lateral não afetaram de forma significativa a precisão. O protótipo não aumentou significativamente o dano mecânico das sementes.