65 resultados para Perturb and Observe


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Cell resistance to glucocorticoids is a major problem in the treatment of nasal polyposis (NP). The objectives of this study were to observe the effect of budesonide on the expression of IL-1 beta, TNF-alpha, granulocyte macrophage-colony stimulating factor, intercellular adhesion molecule (ICAM)-1, basic fibroblast growth factor, eotaxin-2, glucocorticoid receptor (GR)-alpha, GR-beta, c-Fos and p65 in nasal polyps and to correlate their expression to clinical response. Biopsies from nasal polyps were obtained from 20 patients before and after treatment with topical budesonide. Clinical response to treatment was monitored by a questionnaire and nasal endoscopy. The mRNA levels of the studied genes were measured by real-time quantitative (RQ)-PCR. There was a significant decrease in the expression of TNF-alpha (P < 0.05), eotaxin-2 (P < 0.05) and p65 (P < 0.05) in NP after treatment. Poor responders to glucocorticoids showed higher expression of IL-1 beta (3.74 vs. 0.14; P < 0.005), ICAM-1 (1.91 vs. 0.29; P < 0.05) and p65 (0.70 vs. 0.16; P < 0.05) before treatment. Following treatment, IL-1 beta (4.18 vs. 0.42; P < 0.005) and GR-beta (0.95 vs. 0.28; P < 0.05) mRNA expression was higher in this group. Topical budesonide reduced the expression of TNF-alpha, eotaxin-2 and p65. Poor responders to topical budesonide exhibit higher levels of IL-1 beta, ICAM-1 and nuclear factor (NF)-kappa B at diagnosis and higher expression of both IL-1 beta and GR-beta after treatment. These results emphasize the anti-inflammatory action of topical budesonide at the molecular level and its importance in the treatment of NP. Nevertheless, IL-1 beta, ICAM-1 and NF-kappa B may be associated with primary resistance to glucocorticoids in NP, whereas higher expression of GR-beta in poor responders only after glucocorticoid treatment may represent a secondary drug resistance mechanism in this disease.

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Objective: The aim of the present study was to compare the effect of low-dose pilocarpine and cevimeline as stimulants for salivary flow in healthy subjects. Methods: In this cross-over clinical trial with a 1-week washout period, 40 male volunteers were submitted to an oral dose of pilocarpine 1% (Salagen (TM)) -60 mu g kg(-1) body-weight (Group 1) or Cevimeline (Evoxac (TM)) -30 mg (Group 2). Saliva samples were collected and the salivary flow rate was measured (ml min(-1)) at baseline and 20, 40, 60, 80, 140 and 200 min after administration of drugs. In addition, salivary secretion was also measured under mechanical stimulation to observe salivary gland function. Results: The data were analyzed by Friedman and Wilcoxon signed-rank tests (significance level = 5%). Pilocarpine and cevimeline significantly increased salivary flow 140 min after intake. There was a significant higher secretion with cevimeline 140 and 200 min after administration. There were no differences seen among subjects in the salivary glands function by mechanical stimulation. Conclusion: Both drugs showed efficacy in increasing the salivary flow in healthy volunteers, but cevimeline was more effective than pilocarpine.

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Our aim was to investigate whether neonatal LPS challenge may improve hormonal, cardiovascular response and mortality, this being a beneficial adaptation when adult rats are submitted to polymicrobial sepsis by cecal ligation and puncture (CLP). Fourteen days after birth, pups received an intraperitoneal injection of lipopolysaccharide (LPS; 100 mu g/kg) or saline. After 8-12 weeks, they were submitted to CLP, decapitated 4,6 or 24 h after surgery and blood was collected for vasopressin (AVP), corticosterone and nitrate measurement, while AVP contents were measured in neurohypophysis, supra-optic (SON) and paraventricular (PVN) nuclei. Moreover, rats had their mean arterial pressure (MAP) and heart rate (HR) evaluated, and mortality and bacteremia were determined at 24 h. Septic animals with neonatal LPS exposure had higher plasma AVP and corticosterone levels, and higher c-Fos expression in SON and PVN at 24 h after surgery when compared to saline treated rats. The LPS pretreated group showed increased AVP content in SON and PVN at 6 h, while we did not observe any change in neurohypophyseal AVP content. The nitrate levels were significantly reduced in plasma at 6 and 24 h after surgery, and in both hypothalamic nuclei only at 6 h. Septic animals with neonatal LPS exposure showed increase in MAP during the initial phase of sepsis, but HR was not different from the neonatal saline group. Furthermore, neonatally LPS exposed rats showed a significant decrease in mortality rate as well as in bacteremia. These data suggest that neonatal LPS challenge is able to promote beneficial effects on neuroendocrine and cardiovascular responses to polymicrobial sepsis in adulthood. (C) 2011 Elsevier B.V. All rights reserved.

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Objectives: To evaluate the bonding interface in experimentally weakened roots reinforced with adhesive restorative materials and quartz fibre posts, varying the light-exposure time of the composite resin used for root reinforcement. Methods: Twelve extracted human maxillary incisors teeth were used. The crowns were removed and the roots were endodontically treated. After post space preparation, the roots were assigned to four groups. The thickness of the root dentine was reduced and adhesively restored with composite resin light-activated through a translucent fibre post for either 40 s (group 1), 80 s (group 2) or 120 s (group 3). In the case of control (group 4), the roots were not weakened. One day after post cementation, the specimens were sectioned transversally in three slices and processed for scanning electron microscopic analysis to observe bonding interface formation, quality of the hybrid layer and density of resin tags using a four-step scale method. Results: Formation of a hybrid layer and resin tags were evident in all groups. There was no statistically (p > 0.05) significant difference between the regions analysed in each group (Friedman test) and between groups in each section depth (Kruskal-Wallis test). Furthermore, comparison of the flared/reinforced groups showed that the different time;; used for composite resin cure did not affect the results significantly (Kruskal-Wallis test, p = 0.2139). Conclusions: Different light-exposure times used for composite resin polymerisation during root canal reinforcement did not affect significantly the formation and quality of the dentine/adhesive/composite resin bonding interface. (C) 2008 Elsevier Ltd. All rights reserved.

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The diffusion of astrophysical magnetic fields in conducting fluids in the presence of turbulence depends on whether magnetic fields can change their topology via reconnection in highly conducting media. Recent progress in understanding fast magnetic reconnection in the presence of turbulence reassures that the magnetic field behavior in computer simulations and turbulent astrophysical environments is similar, as far as magnetic reconnection is concerned. This makes it meaningful to perform MHD simulations of turbulent flows in order to understand the diffusion of magnetic field in astrophysical environments. Our studies of magnetic field diffusion in turbulent medium reveal interesting new phenomena. First of all, our three-dimensional MHD simulations initiated with anti-correlating magnetic field and gaseous density exhibit at later times a de-correlation of the magnetic field and density, which corresponds well to the observations of the interstellar media. While earlier studies stressed the role of either ambipolar diffusion or time-dependent turbulent fluctuations for de-correlating magnetic field and density, we get the effect of permanent de-correlation with one fluid code, i.e., without invoking ambipolar diffusion. In addition, in the presence of gravity and turbulence, our three-dimensional simulations show the decrease of the magnetic flux-to-mass ratio as the gaseous density at the center of the gravitational potential increases. We observe this effect both in the situations when we start with equilibrium distributions of gas and magnetic field and when we follow the evolution of collapsing dynamically unstable configurations. Thus, the process of turbulent magnetic field removal should be applicable both to quasi-static subcritical molecular clouds and cores and violently collapsing supercritical entities. The increase of the gravitational potential as well as the magnetization of the gas increases the segregation of the mass and magnetic flux in the saturated final state of the simulations, supporting the notion that the reconnection-enabled diffusivity relaxes the magnetic field + gas system in the gravitational field to its minimal energy state. This effect is expected to play an important role in star formation, from its initial stages of concentrating interstellar gas to the final stages of the accretion to the forming protostar. In addition, we benchmark our codes by studying the heat transfer in magnetized compressible fluids and confirm the high rates of turbulent advection of heat obtained in an earlier study.

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The adaptive potential of a species to a changing environment and in disease defence is primarily based on genetic variation. Immune genes, such as genes of the major histocompatibility complex (MHC), may thereby be of particular importance. In marsupials, however, there is very little knowledge about natural levels and functional importance of MHC polymorphism, despite their key role in the mammalian evolution. In a previous study, we discovered remarkable differences in the MHC class II diversity between two species of mouse opossums (Gracilinanus microtarsus, Marmosops incanus) from the Brazilian Atlantic forest, which is one of the most endangered hotspots for biodiversity conservation. Since the main forces in generating MHC diversity are assumed to be pathogens, we investigated in this study gastrointestinal parasite burden and functional associations between the individual MHC constitution and parasite load. We tested two contrasting scenarios, which might explain differences in MHC diversity between species. We predicted that a species with low MHC diversity would either be under relaxed selection pressure by low parasite diversity (`Evolutionary equilibrium` scenario), or there was a recent loss in MHC diversity leading to a lack of resistance alleles and increased parasite burden (`Unbalanced situation` scenario). In both species it became apparent that the MHC class II is functionally important in defence against gastrointestinal helminths, which was shown here for the first time in marsupials. On the population level, parasite diversity did not markedly differ between the two host species. However, we did observe considerable differences in the individual parasite load (parasite prevalence and infection intensity): while M. incanus revealed low MHC DAB diversity and high parasite load, G. microtarsus showed a tenfold higher population wide MHC DAB diversity and lower parasite burden. These results support the second scenario of an unbalanced situation.

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Based on the fact that streamwater quality reflects landscape conditions, the objectives of this study were: to investigate nitrogen (N), carbon (C), and major ion concentrations in six streams crossing minimally disturbed Atlantic Forest areas, with similar geomorphological characteristics; to determine N and C fluxes in one of these pristine streams (Indaia); and assess the impact of human activity on the biogeochemistry of two other streams in the same region, crossing urbanized areas. The distribution pattern of carbon and inorganic nitrogen dissolved forms, as well as the major ion and biogenic gas concentrations in the streamwater, was similar in pristine streams, indicating that the C and N dynamics were determined by influence of some factors, such as climate, atmospheric deposition, geology, soil type, and land covering, which were analogous in the forested watersheds. The urban streams were significantly different from the pristine streams, showing low dissolved oxygen concentrations, high respiration rates, and high concentrations of carbon dioxide, dissolved inorganic nitrogen, dissolved inorganic carbon, and major ion. These differences were attributed to anthropogenic impact on water quality, especially domestic sewage discharge. Additionally, in the Indaia stream, it was possible to observe the importance of rainfall over temporal dynamics of dissolved carbon forms, and also, the obtained specific flux of dissolved inorganic nitrogen was relatively elevated (approximately 11 kg ha(-1) year(-1)). These results reveal the influence of human activity over the biogeochemistry of coastal streams and also indicate the importance N export of Atlantic Forest to the ocean.

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In this paper, we proposed a new two-parameter lifetime distribution with increasing failure rate, the complementary exponential geometric distribution, which is complementary to the exponential geometric model proposed by Adamidis and Loukas (1998). The new distribution arises on a latent complementary risks scenario, in which the lifetime associated with a particular risk is not observable; rather, we observe only the maximum lifetime value among all risks. The properties of the proposed distribution are discussed, including a formal proof of its probability density function and explicit algebraic formulas for its reliability and failure rate functions, moments, including the mean and variance, variation coefficient, and modal value. The parameter estimation is based on the usual maximum likelihood approach. We report the results of a misspecification simulation study performed in order to assess the extent of misspecification errors when testing the exponential geometric distribution against our complementary one in the presence of different sample size and censoring percentage. The methodology is illustrated on four real datasets; we also make a comparison between both modeling approaches. (C) 2011 Elsevier B.V. All rights reserved.

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Assuming that nuclear matter can be treated as a perfect fluid, we study the propagation of perturbations in the baryon density. The equation of state is derived from a relativistic mean field model, which is a variant of the non-linear Walecka model. The expansion of the Euler and continuity equations of relativistic hydrodynamics around equilibrium configurations leads to differential equations for the density perturbation. We solve them numerically for linear and spherical perturbations and follow the propagation of the initial pulses. For linear perturbations we find single soliton solutions and solutions with one or more solitons followed by ""radiation"". Depending on the equation of state a strong damping may occur. We consider also the evolution of perturbations in a medium without dispersive effects. In this case we observe the formation and breaking of shock waves. We study all these equations also for matter at finite temperature. Our results may be relevant for the analysis of RHIC data. They suggest that the shock waves formed in the quark gluon plasma phase may survive and propagate in the hadronic phase. (C) 2009 Elseiver. B.V. All rights reserved.

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We report the first observation of two Cabibbo-suppressed ecay modes, Xi(+)(c) -> Sigma(+)pi(-)pi(+) and Xi c+ -> Sigma(-)pi(+)pi(+). We observe 59 +/- 14 over a background of 87, and 22 +/- 8 over a background of 13 events, respectively, for the signals. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 Gev/c Sigma(-) beam. The branching ratios of the decays relative to the Cabibbo-favored Xi c+ -> Xi(-)pi(+)pi(+) are measured to be B(Xi(+)(c) -> Sigma(+)pi(-)pi(+))/B(Xi(+)(c) -> Xi(-)pi(+)pi(+)) = 0.48 +/- 0.20, and B(Xi(+)(c) -> Sigma(-)pi(+)pi(+))/B(Xi(+)(c) -> Sigma(-)pi(+)pi(+)) = 0.18 +/- 0.09, respectively. We also report branching ratios for the same decay modes of the Delta(+)(c) relative to Delta(+)(c) -> pK(-)pi(+.) (C) 2008 Elsevier B.V. All rights reserved.

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The synthetic lipid 1,2-dimyristoyl-sn-3-phosphoglycerol (DMPG), when dispersed in water/NaCl exhibits a complex phase behavior caused by its almost unlimited swelling in excess water. Using deuterium ((2)H)- and phosphorus ((31)P)-NMR we have studied the molecular properties of DMPG/water/NaCl dispersions as a function of lipid and NaCl concentration. We have measured the order profile of the hydrophobic part of the lipid bilayer with deuterated DMPG while the orientation of the phosphoglycerol headgroup was deduced from the (31)P NMR chemical shielding anisotropy. At temperatures > 30 degrees C we observe well-resolved (2)H- and (31)P NMR spectra not much different from other liquid crystalline bilayers. From the order profiles it is possible to deduce the average length of the flexible fatty acyl chain. Unusual spectra are obtained in the temperature interval of 20-25 degrees C, indicating one or several phase transitions. The most dramatic changes are seen at low lipid concentration and low ionic strength. Under these conditions and at 25 degrees C, the phosphoglycerol headgroup rotates into the hydrocarbon layer and the hydrocarbon chains show larger flexing motions than at higher temperatures. The orientation of the phosphoglycerol headgroup depends on the bilayer surface charge and correlates with the degree of dissociation of DMPG-Na(+). The larger the negative surface charge, the more the headgroup rotates toward the nonpolar region.

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The structural and electronic properties of perylene diimide liquid crystal PPEEB are studied using ab initio methods based on the density functional theory (I)FT). Using available experimental crystallographic data as a guide, we propose a detailed structural model for the packing of solid PPEEB. We find that due to the localized nature of the band edge wave function, theoretical approaches beyond the standard method, such as hybrid functional (PBE0), are required to correctly characterize the band structure of this material. Moreover, unlike previous assumptions, we observe the formation of hydrogen bonds between the side chains of different molecules, which leads to a dispersion of the energy levels. This result indicates that the side chains of the molecular crystal not only are responsible for its structural conformation but also can be used for tuning the electronic and optical properties of these materials.

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We show that halo effects enhance fusion cross sections of weakly bound systems, comparing with the situation when there is no-halo. We introduce dimensionless fusion functions and energy variable quantity to investigate systematical trends in the fusion cross sections of weakly bound nuclei at near-barrier energies. We observe very clearly complete fusion suppression at energies above the barrier due to dynamic effects of the breakup on fusion. We explain this suppression in terms of the repulsive polarization potential produced by the breakup.

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In this work, KHSO(4):Mn crystals doped with Mn and K(2)SO(4) were synthesized using an aqueous solution method. The samples were exposed to ionizing radiation in order to observe the effects on their physical properties. Raman spectroscopy was used to identify the structure of the crystals by detecting the vibrational frequencies of the crystalline lattice. Electron paramagnetic resonance (EPR) was used to study the creation of paramagnetic centers arising from exposure to ionizing radiation. This new synthesis method produces high quality K(2)SO(4) and KHSO(4):Mn crystals and allows control of structural, morphological, optical and magnetic properties. (C) 2009 Elsevier B.V. All rights reserved,

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We observe experimentally a deviation of the radius of a Bose-Einstein condensate from the standard Thomas-Fermi prediction, after free expansion, as a function of temperature. A modified Hartree-Fock model is used to explain the observations, mainly based on the influence of the thermal cloud on the condensate cloud.