Efeito da deficiência de magnésio sobre o metabolismo do tecido ósseo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

M-CSF Priming of Osteoclast Precursors Can Cause Osteoclastogenesis-Insensitivity, Which Can be Prevented and Overcome on Bone

Osteoclasts and macrophages share progenitors that must receive decisive lineage signals driving them into their respective differentiation routes. Macrophage colony stimulation factor M-CSF is a common factor; bone is likely the stimulus for osteoclast differentiation. To elucidate the effect of both, shared mouse bone marrow precursor myeloid blast was pre-cultured with M-CSF on plastic and on bone. M-CSF priming prior to stimulation with M-CSF and osteoclast differentiation factor RANKL resulted in a complete loss of osteoclastogenic potential without bone. Such M-CSF primed cells expressed the receptor RANK, but lacked the crucial osteoclastogenic transcription factor NFATc1. This coincided with a steeply decreased expression of osteoclast genes TRACP and DC-STAMP, but an increased expression of the macrophage markers F4/80 and CD11b. Compellingly, M-CSF priming on bone accelerated the osteoclastogenic potential: M-CSF primed cells that had received only one day M-CSF and RANKL and were grown on bone already expressed an array of genes that are associated with osteoclast differentiation and these cells differentiated into osteoclasts within 2 days. Osteoclastogenesis-insensitive precursors grown in the absence of bone regained their osteoclastogenic potential when transferred to bone. This implies that adhesion to bone dictates the fate of osteoclast precursors. Common macrophage-osteoclast precursors may become insensitive to differentiate into osteoclasts and regain osteoclastogenesis when bound to bone or when in the vicinity of bone. J. Cell. Physiol. 229: 210-225, 2014. (c) 2014 Wiley Periodicals, Inc.

Enoxacin Directly Inhibits Osteoclastogenesis without Inducing Apoptosis

Enoxacin has been identified as a small molecule inhibitor of binding between the B2-subunit of vacuolar H+-ATPase (V-ATPase) and microfilaments. It inhibits bone resorption by calcitriol-stimulated mouse marrow cultures. We hypothesized that enoxacin acts directly and specifically on osteoclasts by disrupting the interaction between plasma membrane-directed V-ATPases, which contain the osteoclast-selective a3-subunit of V-ATPase, and microfilaments. Consistent with this hypothesis, enoxacin dose-dependently reduced the number of multinuclear cells expressing tartrate-resistant acid phosphatase (TRAP) activity produced by RANK-L-stimulated osteoclast precursors. Enoxacin (50 mu M) did not induce apoptosis as measured by TUNEL and caspase-3 assays. V-ATPases containing the a3-subunit, but not the "housekeeping" a1-subunit, were isolated bound to actin. Treatment with enoxacin reduced the association of V-ATPase subunits with the detergent-insoluble cytoskeleton. Quantitative PCR revealed that enoxacin triggered significant reductions in several osteoclast-selective mRNAs, but levels of various osteoclast proteins were not reduced, as determined by quantitative immunoblots, even when their mRNA levels were reduced. Immunoblots demonstrated that proteolytic processing of TRAP5b and the cytoskeletal protein L-plastin was altered in cells treated with 50 mu M enoxacin. Flow cytometry revealed that enoxacin treatment favored the expression of high levels of DC-STAMP on the surface of osteoclasts. Our data show that enoxacin directly inhibits osteoclast formation without affecting cell viability by a novel mechanism that involves changes in post-translational processing and trafficking of several proteins with known roles in osteoclast function. We propose that these effects are downstream to blocking the binding interaction between a3-containing V-ATPases and microfilaments.

Saliva suppresses osteoclastogenesis in murine bone marrow cultures.

Saliva can reach mineralized surfaces in the oral cavity; however, the relationship between saliva and bone resorption is unclear. Herein, we examined whether saliva affects the process of osteoclastogenesis in vitro. We used murine bone marrow cultures to study osteoclast formation. The addition of fresh sterile saliva eliminated the formation of multinucleated cells that stained positive for tartrate-resistant acid phosphatase (TRAP). In line with the histochemical staining, saliva substantially reduced gene expression of cathepsin K, calcitonin receptor, and TRAP. Addition of saliva led to considerably decreased gene expression of receptor activator of nuclear factor kappa-B (RANK) and, to a lesser extent, that of c-fms. The respective master regulators of osteoclastogenesis (c-fos and NFATc1) and the downstream cell fusion genes (DC-STAMP and Atp6v0d2) showed decreased expression after the addition of saliva. Among the costimulatory molecules for osteoclastogenesis, only OSCAR showed decreased expression. In contrast, CD40, CD80, and CD86-all costimulatory molecules of phagocytic cells-were increasingly expressed with saliva. The phagocytic capacity of the cells was confirmed by latex bead ingestion. Based on these in vitro results, it can be concluded that saliva suppresses osteoclastogenesis and leads to the development of a phagocytic cell phenotype.

The mononuclear phagocyte system

The mononuclear phagocyte system (MPS) has been defined as a family of cells comprising bone marrow progenitors, blood monocytes and tissue macrophages. Macrophages are a major cell population in most of the tissues in the body, and their numbers increase further in inflammation, wounding and malignancy. Their trophic roles for other cell types in development and homeostasis are becoming increasingly evident. The receptor for macrophage colony-stimulating factor (CSF-1R) is expressed in a large proportion of cells considered to be mononuclear phagocytes, including antigen-presenting dendritic cells, which can be considered a specialized adaptive state rather than a separate lineage. The unity of the MPS is challenged by evidence that there is a separate embryonic phagocyte lineage, by the transdifferentiation and fusion of MPS cells with other cell types, and by evidence of local renewal of tissue macrophage populations as opposed to monocyte recruitment. The concept of the MPS may have partly outlived its usefulness.

Performance metrics for small-signal stability assessment of DC-distributed power-system-architecture comparisons

The objective of this paper is to provide performance metrics for small-signal stability assessment of a given system architecture. The stability margins are stated utilizing a concept of maximum peak criteria (MPC) derived from the behavior of an impedance-based sensitivity function. For each minor-loop gain defined at every system interface, a single number to state the robustness of stability is provided based on the computed maximum value of the corresponding sensitivity function. In order to compare various power-architecture solutions in terms of stability, a parameter providing an overall measure of the whole system stability is required. The selected figure of merit is geometric average of each maximum peak value within the system. It provides a meaningful metrics for system comparisons: the best system in terms of robust stability is the one that minimizes this index. In addition, the largest peak value within the system interfaces is given thus detecting the weakest point of the system in terms of robustness.

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Número cromossômico em espécies brasileiras de Adesmia DC. (Leguminosae-Faboideae)

Chromosome numbers of 11 South-Brazilian species of Adesmia were determined. The cytological preparations were obtained by squashing cells of root tips, using the acetic-orcein method. The chromosome number for all the species studied was 2n=20, excepting A. incana var. incana with 2n=ca.40. The counts are new for nine species, and the other two agree with the literature. It is suggested x=10 as the basic number for the genus. Up to the present only four species were cited as polyploid.

Anatomia foliar de Eugenia florida DC. (Myrtaceae)

Foi feito o estudo anatômico da folha de Eugenia florida DC., espécie arbórea da família Myrtaceae, coletada no Campus da Fundação Oswaldo Cruz, Rio de Janeiro, RJ. A espécie apresenta importantes propriedades farmacológicas, incluindo-se atividade antiviral. O presente estudo teve como objetivo fornecer dados, revelados através da microscopia óptica e da microscopia eletrônica de varredura, que possam contribuir para o conhecimento da espécie e, conseqüentemente, para a segurança em sua identificação. Anatomicamente, a folha é hipostomática, com organização dorsiventral do mesofilo. Apresenta tricomas simples apenas sobre a nervura mediana da face adaxial. As células epidérmicas apresentam contorno sinuoso em vista frontal e cutícula estriada. O parênquima paliçádico destaca-se pela grande quantidade de cristais prismáticos de oxalato de cálcio. Em posição subepidérmica ocorrem cavidades secretoras de óleos essenciais, pouco numerosas, nas duas faces da lâmina foliar. As células epidérmicas situadas sobre as estruturas secretoras constituem característica de valor diagnóstico e são reconhecíveis pela célula de topo, que é reniforme, circundada pelas adjacentes, que apresentam disposição radiada. A comparação entre folhas de sol e de sombra revela que, nas primeiras, as estruturas secretoras são completamente diferenciadas, ao contrário das folhas de sombra, além de apresentarem maior concentração de compostos ergásticos.

Morfo-anatomia foliar de Myrcia multiflora (Lam.) DC. - Myrtaceae

Folhas de Myrcia multiflora (Lam.) DC. são usadas na medicina popular como hipoglicemiantes. O objetivo deste trabalho foi caracterizar morfológica e anatomicamente as folhas desta planta, de modo que os dados obtidos possam ser utilizados como referência em exames de controle de qualidade de amostras de fármacos, com vistas a verificar a autenticidade. Folhas inteiras foram diafanizadas e coradas para o estudo da nervação. Secções transversais do pecíolo e transversais e paradérmicas da lâmina foliar foram analisadas em microscópio óptico (MO) e a superfície do limbo foi observada, também, em microscopia eletrônica de varredura (MEV). Foram aplicados testes histoquímicos em material fresco, para identificação e localização de glicídios, amido, taninos, lignina, cristais e sílica. Morfologicamente, a folha é simples, oval-elíptica, com margem inteira, base aguda, ápice acuminado e textura cartácea. A venação é do tipo camptódromo-broquidódromo. Anatomicamente, a folha é hipostomática, com mesofilo compacto e dorsiventral, com três estratos de parênquima paliçádico. A epiderme é uniestratificada, silicificada em algumas regiões e as células exibem paredes anticlinais retas. Em posição subepidérmica ocorrem numerosas cavidades secretoras de óleos essenciais. Os feixes vasculares são colaterais e acompanhados por séries cristalíferas. Os dados obtidos são comparados com os de outras espécies de Myrtaceae e conclui-se que as características morfológicas e anatômicas de M. multiflora contribuem para a diagnose.

Analysis of the E-J Curve of HTS Tapes Under DC and AC Magnetic Fields at 77 K

The evaluation of the electrical characteristics of technical HTS tapes are of the key importance in determining the design and operational features of superconducting power apparatuses as well as to understand the external factors which affect the superconducting performance. In this work we report the systematic measurements of the electric field versus current density, E-J relation of short samples for three commercial HTS tapes (BSCCO-2223 tapes, with and without steel reinforcement, and YBCO-coated conductor) at 77 K. In order to get sensitive and noiseless voltage signals the measurements were carried out with DC transport current and subjecting the broad surface tape to DC (0-300 mT) and AC (0-62 mT, 60 Hz) magnetic fields. The voltage is measured by a sensitive nanovoltmeter and the applied magnetic field is monitored by a Hall sensor placed on the tape broad surface. The comparison between the results obtained from the three tapes was done by fitting a power-law equation for currents in the vicinity of the critical current. For the current regime below the critical one a linear correlation of the electric field against the current density is observed. The BSCCO samples presented the same behavior, i.e., a decreasing of n-index with the increasing DC and AC magnetic field strength. Under AC field the decreasing slope of n-index is steeper as compared to DC field. The n-index curve for the YBCO tape showed similar behavior for AC field, however under DC field in the 0-390 mT range exhibited a slight decreasing of the n-index.

Multiobjective Particle Swarm Approach for the Design of a Brushless DC Wheel Motor

The roots of swarm intelligence are deeply embedded in the biological study of self-organized behaviors in social insects. Particle swarm optimization (PSO) is one of the modern metaheuristics of swarm intelligence, which can be effectively used to solve nonlinear and non-continuous optimization problems. The basic principle of PSO algorithm is formed on the assumption that potential solutions (particles) will be flown through hyperspace with acceleration towards more optimum solutions. Each particle adjusts its flying according to the flying experiences of both itself and its companions using equations of position and velocity. During the process, the coordinates in hyperspace associated with its previous best fitness solution and the overall best value attained so far by other particles within the group are kept track and recorded in the memory. In recent years, PSO approaches have been successfully implemented to different problem domains with multiple objectives. In this paper, a multiobjective PSO approach, based on concepts of Pareto optimality, dominance, archiving external with elite particles and truncated Cauchy distribution, is proposed and applied in the design with the constraints presence of a brushless DC (Direct Current) wheel motor. Promising results in terms of convergence and spacing performance metrics indicate that the proposed multiobjective PSO scheme is capable of producing good solutions.

Comparison between DC(+) and Square Wave AC SAW Current Outputs to Weld AISI 304 for Low-Temperature Applications

Welded equipment for cryogenic applications is utilized in chemical, petrochemical, and metallurgical industries. One material suitable for cryogenic application is austenitic stainless steel, which usually doesn`t present ductile/brittle transition temperature, except in the weld metal, where the presence of ferrite and micro inclusions can promote a brittle failure, either by ferrite cleavage or dimple nucleation and growth, respectively. A 25-mm- (1-in.-) thick AISI 304 stainless steel base metal was welded with the SAW process using a 308L solid wire and two kinds of fluxes and constant voltage power sources with two types of electrical outputs: direct current electrode positive and balanced square wave alternating current. The welded joints were analyzed by chemical composition, microstructure characterization, room temperature mechanical properties, and CVN impact test at -100 degrees C (-73 degrees F). Results showed that an increase of chromium and nickel content was observed in all weld beads compared to base metal. The chromium and nickel equivalents ratio for the weld beads were always higher for welding with square wave AC for the two types of fluxes than for direct current. The modification in the Cr(eq)/Ni(eq) ratio changes the delta ferrite morphology and, consequently, modifies the weld bead toughness at lower temperatures. The oxygen content can also affect the toughness in the weld bead. The highest absorbed energy in a CVN impact test was obtained for the welding condition with square wave AC electrical output and neutral flux, followed by DC(+) electrical output and neutral flux, and square wave AC electrical output and alloyed flux.

A new variety of the weed Borreria densiflora DC. (Rubiaceae)

The weed, known commonly as vassourinha de botao (buttonweed), is present in several crops in northern and north-eastern Brazil. Its occurrence is common in sugarcane and soybean crops in the states of Goias, Tocantins, and Maranhao. However, there is no published information in the literature about its taxonomic classification. Thus, this research aimed to classify taxonomically this species in order to develop a classification key based on the morphological characteristics among varieties of Borreria densiflora DC., as well as to illustrate it and provide a palynological basis to classify this species as a new variety For the classification process, data from the literature, morphological characteristics, and palynological evidence were considered. In this article, we describe a new variety, B. densiflora DC. var. latifolia E.L. Cabral & Martins. The new variety possesses a terrestrial habitat and it is a simple perennial weed species. These results show the importance of an accurate identification, as well as an understanding of the evolutionary changes inherent to weeds (like intraspecific variability), breeding system, genetic potential, and ecological studies. Those factors are essential to the beginning of a long-term weed management strategy.