957 resultados para POLAR-MOLECULES
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A thorough census of Admiralty Bay benthic biodiversity was completed through the synthesis of data, acquired from more than 30 years of observations. Most of the available records arise from successive Polish and Brazilian Antarctic expeditions organized since 1977 and 1982, respectively, but also include new data from joint collecting efforts during the International Polar Year (2007-2009). Geological and hydrological characteristics of Admiralty Bay and a comprehensive species checklist with detailed data on the distribution and nature of the benthic communities are provided. Approximately 1300 species of benthic organisms (excluding bacteria, fungi and parasites) were recorded from the bay`s entire depth range (0-500 m). Generalized classifications and the descriptions of soft-bottom and hard-bottom invertebrate communities are presented. A time-series analysis showed seasonal and interannual changes in the shallow benthic communities, likely to be related to ice formation and ice melt within the bay. As one of the best studied regions in the maritime Antarctic Admiralty Bay represents a legacy site, where continued, systematically integrated data sampling can evaluate the effects of climate change on marine life. Both high species richness and high assemblage diversity of the Admiralty Bay shelf benthic community have been documented against the background of habitat heterogeneity. (C) 2010 Elsevier Ltd. All rights reserved.
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Several reefs of the world have undergone changes in community due to sedimentation processes. It has been suggested that Abrolhos reefs (Brazil/South-West Atlantic) are subjected to a steady coastal influence, although there is still little information regarding this assumption. In this work, we have analyzed a set of environmental parameters concerning sedimentation characteristics at the Abrolhos reefs, near 18 degrees S-39 degrees W. The analysis included remote sensing, model and in situ data to provide a three-dimensional quantitative description of the processes that influence sediment apportionment to the reefs. Mineralogy and natural radioactivity of sediment trapped at three reef sites in a transect perpendicular to the coastline were used in conjunction with numerical weather prediction model and remote sensing databases. We have observed an increase of around 100% of sediment flux during the summer compared to the winter season. A comparison of regional rainfall regime, sediment plume dynamics and a year-around monitoring of polar fronts trajectories and surface wind showed that the wind-driven resedimentation due to polar front activity is the major contributor to the intensification of sedimentation processes at the offshore area of Abrolhos reefs, despite river runoff from mainland. (C) 2007 Elsevier Ltd. All rights reserved.
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Pulmonary involvement in leptospirosis has been increasingly reported in the last 20 years, being related to the severity and mortality of the disease. The pathogenesis of pulmonary hemorrhage in leptospirosis is not understood. Lung endothelial cells have been proposed as targets in the pathogenesis of lung involvement in leptospirosis through the activation of Toll-like receptor 2 or the complement system, which stimulates the release of cytokines that lead to the activation of adhesion molecules. The aim of this study was to investigate the involvement of immune pathways and of the intercellular and vascular cell adhesion molecules (intercellular adhesion molecule and vascular cell adhesion molecule, respectively) in the lungs of patients with pulmonary involvement of leptospirosis. We studied the lungs of 18 patients who died of leptospirosis and compared them with 2 groups of controls: normal and noninfectious hemorrhagic lungs. Using immunohistochemistry and image analysis, we quantified the expression of the C3a anaphylatoxin receptor, intercellular adhesion molecule, vascular cell adhesion molecule, and Toll-like receptor 2 in small pulmonary vessels and in the alveolar septa. There was an increased expression of intercellular adhesion molecule (P <.03) and C3a anaphylatoxin receptor (P <.008) in alveolar septa in the leptospirosis group compared with the normal and hemorrhagic controls. In the vessels of the leptospirosis group, there was an increased expression of intercellular adhesion molecule (P=.004), vascular cell adhesion molecule (P=.030), and Toll-like receptor 2 (P=.042) compared with the normal group. Vascular cell adhesion molecule expression in vessels was higher in the leptospirosis group compared with the hemorrhagic group (P=.015). Our results indicate that immune receptors and adhesion molecules participate in the phenomena leading to pulmonary hemorrhage in leptospirosis. (C) 2012 Elsevier Inc. All rights reserved.
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During sporulation, Bacillus subtilis redeploys the division protein FtsZ from midcell to the cell poles, ultimately generating an asymmetric septum. Here, we describe a sporulation-induced protein, RefZ, that facilitates the switch from a medial to a polar FtsZ ring placement. The artificial expression of RefZ during vegetative growth converts FtsZ rings into FtsZ spirals, arcs, and foci, leading to filamentation and lysis. Mutations in FtsZ specifically suppress RefZ-dependent division inhibition, suggesting that RefZ may target FtsZ. During sporulation, cells lacking RefZ are delayed in polar FtsZ ring formation, spending more time in the medial and transition stages of FtsZ ring assembly. A RefZ-green fluorescent protein (GFP) fusion localizes in weak polar foci at the onset of sporulation and as a brighter midcell focus at the time of polar division. RefZ has a TetR DNA binding motif, and point mutations in the putative recognition helix disrupt focus formation and abrogate cell division inhibition. Finally, chromatin immunoprecipitation assays identified sites of RefZ enrichment in the origin region and near the terminus. Collectively, these data support a model in which RefZ helps promote the switch from medial to polar division and is guided by the organization of the chromosome. Models in which RefZ acts as an activator of FtsZ ring assembly near the cell poles or as an inhibitor of the transient medial ring at midcell are discussed.
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T regulatory cells (Tregs) play an important role in the mechanism of host's failure to control pathogen dissemination in severe forms of different chronic granulomatous diseases, but their role in leprosy has not yet been elucidated; 28 newly diagnosed patients (16 patients with lepromatous leprosy and 12 patients with tuberculoid leprosy) and 6 healthy Mycobacterium leprae-exposed individuals (contacts) were studied. Tregs were quantified by flow cytometry (CD4+ CD25+ Foxp3+) in peripheral blood mononuclear cells stimulated in vitro with a M. leprae antigenic preparation and phytohemagglutinin as well as in skin lesions by immunohistochemistry. The lymphoproliferative (LPR), interleukin-10 (IL-10), and interferon-gamma (IFN-gamma) responses of the in vitro-stimulated peripheral blood mononuclear cells and the in situ expression of IL-10, transforming growth factor-beta (TGF-beta), and cytotoxic T-lymphocyte antigen 4 (CTLA-4) were also determined. We show that M. leprae antigens induced significantly lower LPR but significantly higher Treg numbers in lepromatous than tuberculoid patients and contacts. Mitogen-induced LPR and Treg frequencies were not significantly different among the three groups. Tregs were also more frequent in situ in lepromatous patients, and this finding was paralleled by increased expression of the antiinflammatory molecules IL-10 and CTLA-4 but not TGF-beta. In lepromatous patients, Tregs were intermingled with vacuolized hystiocyte infiltrates all over the lesion, whereas in tuberculoid patients, Tregs were rare. Our results suggest that Tregs are present in increased numbers, and they may have a pathogenic role in leprosy patients harboring uncontrolled bacillary multiplication but not in those individuals capable of limiting M. leprae growth.
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We use the QCD sum rules to study possible B-c-like molecular states. We consider isoscalar J(P) = 0(+) and J(P) = 1(+) D(*) B(*) molecular currents. We consider the contributions of condensates up to dimension eight and we work at leading order in alpha(s). We obtain for these states masses around 7 GeV. (C) 2012 Elsevier B.V. All rights reserved.
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This paper describes the preparation, characterization, and use of poly (methylene blue) (PMB)-modified glassy carbon electrodes (GCE) (GCE-PMB) in the detection of the thiols L-cysteine (L-CySH) and N-acetyl cysteine (Acy), and the herbicide glyphosate (GLYP) in pH 5.3 aqueous solution. The polymer film prepared by electropolymerization showed different characteristics such as robustness, stability, and redox properties satisfactorily. The surface coverage concentration (Gamma) of PMB was found to be 7.90 x 10(-9) - mol cm(-2). Moreover, we observed strong adhesion of the polymer film to the electrode surface. The results using GCE-PMB as a sensor indicated that this modified electrode exhibited electrocatalytic activity toward the detection of thiols and glyphosate in 0.1 mol L-1 KO (pH 5.3). Meanwhile, strong adsorption of the analytes on the GCE-PMB electrodes was also observed. Otherwise, using a low concentration (1 x 10(-4) mol L-1) of L-cysteine and N-acetyl cysteine and 8.9 x 10(-6) mol L-1 of glyphosate, separately, it was possible to observe a well-defined electrochemical response, thus providing an opportunity to further understand the applicability of PMB as a sensor for amino acid-based molecules. (C) 2012 Elsevier B.V. All rights reserved.
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Some atomic multipoles (charges, dipoles and quadrupoles) from the Quantum Theory of Atoms in Molecules (QTAIM) and CHELPG charges are used to investigate interactions between a proton and a molecule (F2, Cl2, BF, AlF, BeO, MgO, LiH, H2CO, NH3, PH3, BF3, and CO2). Calculations were done at the B3LYP/6-311G(3d,3p) level. The main aspect of this work is the investigation of polarization effects over electrostatic potentials and atomic multipoles along a medium to long range of interaction distances. Large electronic charge fluxes and polarization changes are induced by a proton mainly when this positive particle approaches the least electronegative atom of diatomic heteronuclear molecules. The search for simple equations to describe polarization on electrostatic potentials from QTAIM quantities resulted in linear relations with r-4 (r is the interaction distance) for many cases. Moreover, the contribution from atomic dipoles to these potentials is usually the most affected contribution by polarization what reinforces the need for these dipoles to a minimal description of purely electrostatic interactions. Finally, CHELPG charges provide a description of polarization effects on electrostatic potentials that is in disagreement with physical arguments for certain of these molecules. (c) 2012 Wiley Periodicals, Inc.
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This work reports the analytical application of surface-enhanced Raman spectroscopy (SERS) in the trace analysis of organophosphorous pesticides (trichlorfon and glyphosate) and model organophosphorous compounds (dimethyl methylphosphonate and o-ethyl methylphosphonothioate) bearing different functional groups. SERS measurements were carried out using Ag nanocubes with an edge square dimension of ca. 100 nm as substrates. Density functional theory (DFT) with the B3LYP functional was used for the optimization of ground state geometries and simulation of Raman spectra of the organophosphorous compounds and their silver complexes. Adsorption geometries and marker bands were identified for each of the investigated compound. Results indicate the usefulness of SERS methodology for the sensitive analyses of organophosphorous compounds through the use of vibrational spectroscopy.
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Background: The objective of this study was to evaluate the effect of three contraceptive pills containing ethinylestradiol (EE) (20 or 30 mcg) in combination with drospirenone (DRSP) and levonorgestrel (LNG) on plasma concentration of adhesion molecules vascular cell adhesion molecule -1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and E-selectin. Study Design: A cross-sectional study was conducted with 72 participants (18-30 years old) distributed into three groups that used oral contraceptives containing EE 20 or 30 mcg combined with DRSP 3 mg or EE 30 mcg/LNG 150 mcg for at least 6 months. The control group was comprised of nonusers of contraceptives. Soluble VCAM-1, soluble ICAM-1 and soluble E-selectin were evaluated by enzyme-linked immunosorbent assay. Results: Compared to the control group, a significant decrease was found in VCAM-1 and ICAM-1 concentrations with use of DRSP/20 EE and LNG/30 EE. Conclusions: DRSP/20 EE and LNG/30 EE induce favorable changes in endothelial function. (C) 2012 Elsevier Inc. All rights reserved.
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A high-performance liquid chromatographic method using polar organic mode was developed to analyze albendazole (ABZ), albendazole sulfone (ABZSO(2)) and the chiral and active metabolite albendazole sulfoxide (ABZSOX, ricobendazole) that was further applied in stereoselective fungal biotransformation studies. The chromatographic separation was performed on a Chiralpak AS column using acetonitrile:ethanol (97:3, v/v) plus 0.2% triethylamine and 0.2% acetic acid as the mobile phase at a flow rate of 0.5 mL min(-1). The present study employed hollow fiber liquid-phase microextraction as sample preparation. The method showed to be linear over the concentration range of 25-5000 ng mL(-1) for each ABZSOX enantiomer, 200-10,000 ng mL(-1) for ABZ and 50-1000 ng mL(-1) for ABZSO(2) metabolite with correlation coefficient (r)> 0.9934. The mean recoveries for ABZ, rac-ABZSOX and ABZSO(2) were, respectively, 9%, 33% and 20% with relative standard deviation below 10%. Within-day and between-day precision and accuracy assays for these analytes were studied at three concentration levels and were lower than 15%. This study opens the door regarding the possibility of using fungi in obtaining of the active metabolite ricobendazole. Nigrospora sphaerica (Sacc.) E. W. Mason (5567), Pestalotiopsis foedans (VR8), Papulaspora immersa Hotson (SS13) and Mucor rouxii were able to stereoselectively metabolize ABZ into its chiral metabolite. Among them, the fungus Mucor rouxii was the most efficient in the production of (+)-ABZSOX. (C) 2011 Elsevier B.V. All rights reserved.
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We discuss the possibility of observing a loosely bound molecular state in a three-body hadronic B decay. In particular, we use the QCD sum rule approach to study eta' - pi molecular current. We consider an isovector-scalar I(G)J(PC) = 1(-)0(++) molecular current, and we use two- and three-point functions to study the mass and decay width of such a state. We consider the contributions of condensates up to dimension six, and we work at leading order in alpha(s). We obtain a mass around 1.1 GeV, consistent with a loosely bound state, and eta' - pi -> K+K- decay width around 10 MeV.
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This Article reports a combined experimental and theoretical analysis on the one and two-photon absorption properties of a novel class of organic molecules with a pi-conjugated backbone based on phenylacetylene (JCM874, FD43, and FD48) and azoaromatic (YB3p2S) moieties. Linear optical properties show that the phenylacetylene-based compounds exhibit strong molar absorptivity in the UV and high fluorescence quantum yield with lifetimes of approximately 2.0 ns, while the azoaromatic-compound has a strong absorption in the visible region with very low fluorescence quantum yield. The two-photon absorption was investigated employing nonlinear optical techniques and quantum chemical calculations based on the response functions formalism within the density functional theory framework. The experimental data revealed well-defined 2PA spectra with reasonable cross-section values in the visible and IR. Along the nonlinear spectra we observed two 2PA allowed bands, as well as the resonance enhancement effect due to the presence of one intermediate one-photon allowed state. Quantum chemical calculations revealed that the 2PA allowed bands correspond to transitions to states that are also one-photon allowed, indicating the relaxation of the electric-dipole selection rules. Moreover, using the theoretical results, we were able to interpret the experimental trends of the 2PA spectra. Finally, using a few-energy-level diagram, within the sum-over-essential states approach, we observed strong qualitative and quantitative correlation between experimental and theoretical results.
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Introduction: Cell adhesion molecules (CAM) are required for maintaining a normal epithelial phenotype, and abnormalities in CAM expression have been related to cancer progression, including bladder urothelial carcinomas. There is only one study that correlates E-cadherin and alpha-, beta- and gamma-catenin expression with prognosis of upper tract urothelial carcinomas. Our aim is to study the pattern of immune expression of these CAMs in urothelial carcinomas from the renal pelvis and ureter in patients who have been treated surgically. Our goal is to correlate these expression levels and characteristics with well-known prognostic parameters for disease-free survival. Materials and Methods: We evaluated specimens from 20 patients with urothelial carcinomas of the renal pelvis and ureter who were treated with nephroureterectomy or ureterectomy between June 1997 and January 2007. CAM expression was evaluated by immunohistochemistry in a tissue microarray and correlated with histopathological characteristics and patient outcomes after a mean follow-up of 55 months. Results: We observed a relationship between E-cadherin expression and disease recurrence. Disease recurrence occurred in 87.5% of patients with strong E-cadherin expression. Only 50.0% of patients with moderate expression and 0% of patients with weak or no expression of E-cadherin had disease recurrence (p = 0.014). There was also a difference in disease-free survival. Patients with strong E-cadherin expression had a mean disease-free survival rate of 49.1 months, compared to 83.9 months for patients with moderate expression (p = 0.011). Additionally, an absence of a-catenin expression was associated with tumors that were larger than 3 cm (p = 0.003). Conclusions: We demonstrated for the first time that immune expression of E-cadherin is related to tumor recurrence and disease-free survival rates, and the absence of a-catenin expression is related to tumor size in upper tract urothelial carcinomas.
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Background The risks of hormone replacement therapy have led to a search for new alternatives such as phytoestrogens, plant compounds with estrogen-like biological activity. Isoflavones are the phytoestrogens most extensively studied and can be found in soybean, red clover and other plants. Due to this estrogen-like activity, phytoestrogens can have some effect on atherosclerosis. Human umbilical vein endothelial cells (HUVEC) have been extensively used to study the biology and pathobiology of human endothelial cells and most of the knowledge acquired is due to experiments with cultures of these cells. Objective To evaluate the effects of the phytoestrogen extracts from Glycine max soy bean, genistein, formononetin, biochanin A and daidzein, as well as a mixture of these extracts (Mix), on expression of adhesion molecules, VCAM-1, ICAM-1 and E-selectin, by endothelial cell HUVEC, stimulated with lipopolysaccharide. Methods HUVEC were cultured in medium EBM2, pretreated with isoflavones for 24 and 48 h and then stimulated with lipopolysaccharide; in addition, isoflavones were added, after stimulation by lipopolysaccharide, to HUVEC. We evaluated the production of VCAM-1, ICAM-1 and E-selectin on cell surface, by cell-based enzyme immunoassay, and of sVCAM-1, sICAM-1 and sE-selectin in culture supernatant, by ELISA. Results Genistein, formononetin, biochanin A and daidzein, as well as the Mix were able to reduce VCAM-1, ICAM-1 and E-selectin on cell surface and in culture supernatant. Conclusion Isoflavones extracted from Glycine max soy bean, in vitro, presented antiatherogenic effects, reducing the expression of adhesion molecules and acting as preventive agents as well as therapeutic agents.