927 resultados para National Research Council Canada


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The Atlantic Forest is one of the most important biomes of Brazil. Originally covering approximately 1.5 million of km(2), today this area has been reduced to 12% of its original size. Climate changes may alter the structure and the functioning of this tropical forest. Here we explore how increases in temperature and changes in precipitation distribution could affect dynamics of carbon and nitrogen in coastal Atlantic Forest of the southeast region of Brazil The main conclusion of this article is that the coastal Atlantic Forest has high stocks of carbon and nitrogen above ground, and especially, below ground. An increase in temperature may transform these forests from important carbon sinks to carbon sources by increasing loss of carbon and nitrogen to the atmosphere. However, this conclusion should be viewed with caution because it is based on limited information. Therefore, more studies are urgently needed to enable us to make more accurate predictions.

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Introduction: Studies designed to investigate chronic rhinosinusitis (CRS) epidemiology play an important role to assess population's distribution and risk factors to result in the development and promotion of public health policies. Method: This study design is a survey carried out with a complex two-stage cluster sampling plan. Personal interviews were carried out with 2,003 individuals. The questionnaire included the epidemiological criteria for CRS. Demographic data, history of physician-diagnosed respiratory diseases (asthma, sinusitis, rhinitis), smoking, family income, educational attainment, and household characteristics were also evaluated. Results: The overall response rate was 93.9% of the households. Mean age was 39.8 +/- 21 years; 45.33% were male. The overall prevalence of CRS in the city of Sao Paulo was 5.51%. We found a significant association between diagnosis of CRS and diagnosis of asthma and CRS and diagnosis of rhinitis and a significant association between presence of CRS and belonging to the low-income subgroup. Conclusion: The municipality of Sao Paulo has an urban population of 11 million. According to the present study, the prevalence of CRS is 5.51%, which represents more than 500,000 individuals affected by this condition in the city.

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We studied locomotor activity rhythms of C57/Bl6 mice under a chronic jet lag (CJL) protocol (ChrA(6/2)), which consisted of 6-hour phase advances of the light-dark schedule (LD) every 2 days. Through periodogram analysis, we found 2 components of the activity rhythm: a short-period component (21.01 +/- 0.04 h) that was entrained by the LD schedule and a long-period component (24.68 +/- 0.26 h). We developed a mathematical model comprising 2 coupled circadian oscillators that was tested experimentally with different CJL schedules. Our simulations suggested that under CJL, the system behaves as if it were under a zeitgeber with a period determined by (24 -[phase shift size/days between shifts]). Desynchronization within the system arises according to whether this effective zeitgeber is inside or outside the range of entrainment of the oscillators. In this sense, ChrA(6/2) is interpreted as a (24 - 6/2 = 21 h) zeitgeber, and simulations predicted the behavior of mice under other CJL schedules with an effective 21-hour zeitgeber. Animals studied under an asymmetric T = 21 h zeitgeber (carried out by a 3-hour shortening of every dark phase) showed 2 activity components as observed under ChrA(6/2): an entrained short-period (21.01 +/- 0.03 h) and a long-period component (23.93 +/- 0.31 h). Internal desynchronization was lost when mice were subjected to 9-hour advances every 3 days, a possibility also contemplated by the simulations. Simulations also predicted that desynchronization should be less prevalent under delaying than under advancing CJL. Indeed, most mice subjected to 6-hour delay shifts every 2 days (an effective 27-hour zeitgeber) displayed a single entrained activity component (26.92 +/- 0.11 h). Our results demonstrate that the disruption provoked by CJL schedules is not dependent on the phase-shift magnitude or the frequency of the shifts separately but on the combination of both, through its ratio and additionally on their absolute values. In this study, we present a novel model of forced desynchronization in mice under a specific CJL schedule; in addition, our model provides theoretical tools for the evaluation of circadian disruption under CJL conditions that are currently used in circadian research.

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To confirm that Beagle dogs are a good experimental model for Chagas disease, we evaluated hematological alterations during the acute and chronic phases in Beagle dogs infected with the Y, Berenice-78 (Be-78) and ABC strains of Trypanosoma cruzi, correlating clinical signs with the parasitemia curve. We demonstrate that the acute phase of infection was marked by lethargy and loss of appetite. Simultaneously, we observed anemia, leukocytosis and lymphocytosis. Also,we describe hematological alterations and clinical signs that were positively correlated with the parasitemia during the experimental infection with the three strains of T cruzi, and demonstrate that experimental infection of Beagle is a trustworthy model for Chagas disease.

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Introduction: The aim of this study was to evaluate the pH, calcium ion release, setting time, and solubility of white mineral trioxide aggregate (WMTA) and white Portland cement (WPC) combined with the following radiopacifying agents: bismuth oxide (BO), calcium tungstate (CT), and zirconium oxide (ZO). Methods: Fifty acrylic teeth with root-end filling material were immersed in ultrapure water for measurement of pH and calcium release (atomic absorption spectrophotometry) at 3, 24, 72, and 168 hours. For evaluation of setting time, each material was analyzed according to the American Society for Testing and Materials guidelines 266/08. The solubility test was performed according to American National Standards Institute/American Dental Association specification no. 57/2000. Solubility, setting time, and pH values were compared by using analysis of variance and Tukey test, and the values of calcium release were compared by the Kruskal-Wallis and Miller tests. The significance level was set at 5%. Results: The pH and calcium release were higher at 3 and 24 hours. WPC was the material with the higher values for both properties. WMTA had the greatest solubility among all materials (P < .05). All radiopacifiers increased the setting time of WPC, and WMTA had the shortest setting time among all materials (P < .05). Conclusions: All materials released calcium ions. Except for WPC/CT at 168 hours, all materials promoted an alkaline pH. On the basis of the obtained results, ZO and CT can be considered as potential radiopacifying agents to be used in combination with Portland cement. (J Endod 2012;38:394-397)

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Most of the metals released from industrial activity, among them are cadmium (Cd) and nickel (Ni), inhibit the productivity of cultures and affect microbial metabolism. In this context, the aim of this work was to investigate the capacity of sugar cane vinasse to mitigate the adverse effects of Cd and Ni on cell growth, viability, budding rate and trehalose content of Saccharomyces cerevisiae, likely because of adsorption and chelating action. For this purpose, the yeast was grown batch-wise in YED medium supplemented with selected amounts of vinasse and Cd or Ni. The negative effects of Cd and Ni on S. cerevisiae growth and the mitigating one of sugar cane vinasse were quantified by an exponential model. Without vinasse, the addition of increasing levels of Cd and Ni reduced the specific growth rate, whereas in its presence no reduction was observed. Consistently with the well-proved toxicity of both metals, cell viability and budding rate progressively decreased with increasing their concentration, but in the presence of vinasse the situation was remarkably improved. The trehalose content of S. cerevisiae cells followed the same qualitative behavior as cell viability, even though the negative effect of both metals on this parameter was stronger. These results demonstrate the ability of sugar cane vinasse to mitigate the toxic effects of Cd and Ni.

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Hydrocephalus is associated with reduced blood flow in periventricular white matter. To investigate hypoxic and oxidative damage in the brains of rats with hydrocephalus, kaolin was injected into the cisterna magna of newborn 7- and 21-day-old Sprague-Dawley rats, and ventricle size was assessed by magnetic resonance imaging at 7, 21, and 42 days of age. In-situ evidence of hypoxia in periventricular capillaries and glial cells was shown by pimonidazole hydrochloride binding. Biochemical assay of thiobarbituric acid reaction and immunohistochemical detection of malondialdehyde and 4-hydroxy-2-nonenal indicated the presence of lipid peroxidation in white matter. Biochemical assay of nitrite indicated increased nitric oxide production. Nitrotyrosine immunohistochemistry showed nitrosylated proteins in white matter reactive microglia and astrocytes. Activities of the antioxidant enzymes catalase and glutathione peroxidase were not increased, and altered hypoxia-inducible factor 1 alpha was not detected by quantitative reverse transcription-polymerase chain reaction. Cerebral vascular endothelial growth factor expression determined by quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay was not changed, but vascular endothelial growth factor immunoreactivity was increased in reactive astrocytes of hydrocephalic white matter. To determine if nitric oxide synthase is involved in the pathogenesis, we induced hydrocephalus in 7-day-old wild-type and neuronal nitric oxide synthase-deficient mice. At 7 days, the wild-type and mutant mice exhibited equally severe ventriculomegaly and no behavioral differences, although increased glial fibrillary acidic protein was less in the mutant mice. We conclude that hypoxia, via peroxidation and nitrosylation, contributes to brain changes in young rodents with hydrocephalus and that compensatory mechanisms are negligible.

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Paracoccidioidomycosis is a granulomatous pulmonary infection that is generally controlled by chemotherapy. The efficacy of treatment, however, is limited by the status of the host immune response. The inhibition of a Th-2 immunity or the stimulation of Th-1 cytokines generally increases the efficacy of antifungal drugs.(1) This has been achieved by immunization with an internal peptide of the major diagnostic antigen gp43 of Paracoccidioides brasiliensis. Peptide 10 (QTLIAIHTLAIRYAN) elicits an IFN-gamma rich Th-1 immune response that protects against experimental intratracheal infection by this fungus. The combination of chemotherapy with P10 immunization showed additive protective effect even after 30 d of infection or in anergic mice, rendering in general, increased production of IL-12 and IFN-gamma and reduction of IL-4 and IL-10. Immunotherapy with P10 even in the absence of simultaneous chemotherapy has been effective using various protocols, adjuvants, nanoparticles, P10-primed dendritic cells, and especially a combination of plasmids encoding the P10 minigene and IL-12. Gene therapy, in a long-term infection protocol succeeded in the virtual elimination of the fungus, preserving the lung structure, free from immunopathological side effects.

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Interfacial concentrations of chloride and bromide ions, with Li+, Na+, K+, Rb+, Cs+, trimethylammonium (TMA(+)), Ca2+, and Mg2+ as counterions, were determined by chemical trapping in micelles formed by two zwitterionic surfactants, namely N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS) and hexadecylphosphorylcholine (HDPC) micelles. Appropriate standard curves for the chemical trapping method were obtained by measuring the product yields of chloride and bromide salts with 2,4,6-trimethyl-benzenediazonium (BF4) in the presence of low molecular analogs (N,N,N-trimethyl-propane sulfonate and methyl-phosphorylcholine) of the employed surfactants. The experimentally determined values for the local Br- (Cl-) concentrations were modeled by fully integrated non-linear Poisson Boltzmann equations. The best fits to all experimental data were obtained by considering that ions at the interface are not fixed at an adsorption site but are free to move in the interfacial plane. In addition, the calculation of ion distribution allowed the estimation of the degree of ion coverage by using standard chemical potential differences accounting for ion specificity. (C) 2012 Elsevier Inc. All rights reserved.

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In this study, we evaluated the effects of obesity and insulin resistance induced by a high-fat diet on prostate morphophysiology, focusing on cell proliferation, expression of androgen (AR) and estrogen receptors (ER) and proteins of the insulin signaling pathway. Adult male Wistar rats were fed a high-fat diet (20% fat) for 15 weeks, whereas control animals received a balanced diet (4% fat). Both groups were then divided and treated for 2 weeks with 1 mg/kg body weight/day of the aromatase inhibitor letrozole or vehicle only. The ventral prostate was analyzed with immunohistochemical, histopathological, stereological, and Western blotting methods. Obese rats showed insulin resistance, hyperinsulinemia, and reduced plasma testosterone levels. The incidence of prostatic intraepithelial neoplasia (PIN) was 2.7 times higher in obese rats and affected 0.4% of the gland compared with 0.1% PIN areas found in control rats. Obesity doubled cell proliferation in both prostate epithelium and stroma. AR content decreased in the prostate of obese rats and estrogen receptor beta (ER beta) increased in this group. Protein levels of insulin receptor substrate 1 and protein kinase B diminished in the obese group, whereas phosphatidylinositol 3-kinase (PI3K) increased significantly. Most structural changes observed in the prostate of obese rats normalized after letrozole treatment, except for increased stromal cell proliferation and ER beta expression, which might be associated with insulin resistance. This experimental model of obesity and insulin resistance induced by a high-fat diet increases cell proliferation in rat prostate. Such alterations are associated with decreased levels of AR and increased ER beta and PI3K proteins. This change can facilitate the establishment of proliferative lesions in rat prostate.

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This paper provides additional validation to the problem of estimating wave spectra based on the first-order motions of a moored vessel. Prior investigations conducted by the authors have attested that even a large-volume ship, such as an FPSO unit, could be adopted for on-board estimation of the wave field. The obvious limitation of the methodology concerns filtering of high-frequency wave components, for which the vessel has no significant response. As a result, the estimation range is directly dependent on the characteristics of the vessel response. In order to extend this analysis, further small-scale tests were performed with a model of a pipe-laying crane-barge. When compared to the FPSO case, the results attest that a broader range of typical sea states can be accurately estimated, including crossed-sea states with low peak periods. (C) 2012 Elsevier Ltd. All rights reserved.

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The nesting biology and social behavior of the euglossine bee species Euglossa melanotricha was analyzed based on the monitoring of eight nests found in man-made cavities and transferred to observation boxes. Euglossa melanotricha females usually construct their nests in cavities in the ground, in buildings, or in mounds. In this study, we present new data on the nesting biology of E. melanotricha. The process of reactivation of nests was commonly observed with one to three females participating in the reactivation. The duration of the process of reactivation ranged from 10 to 78 days (n = 31) and were longer during the rainy season. Time spent (in days) for provisioning, oviposition and closing a single cell was higher in reactivations that occurred during the dry period. 151 emergences were observed (39 males and 112 females). 90 (80.3%) of the emerged females returned to the natal nest, but only 35(38.9%) remained and actively participated in the construction and provisioning of cells. The other 55 abandoned the nests after several days without performing any work in the nest. Matrifilial nest structure was regulated by dominance-subordinate aggressive behavior among females, where the dominant female laid almost all eggs. Task allocation was recognized by behavioral characteristics, namely, agonism and oophagy in cells oviposited by other females. Euglossa melanotricha is multivoltine and its nesting is asynchronous with respect to season. Our observations suggest a primitively eusocial organization. These observations of E. melanotricha provide valuable information for comparison with other species of Euglossa in an evolutionary context.

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The Amazon basin is a region of constant scientific interest due to its environmental importance and its biodiversity and climate on a global scale. The seasonal variations in water volume are one of the examples of topics studied nowadays. In general, the variations in river levels depend primarily on the climate and physics characteristics of the corresponding basins. The main factor which influences the water level in the Amazon Basin is the intensive rainfall over this region as a consequence of the humidity of the tropical climate. Unfortunately, the Amazon basin is an area with lack of water level information due to difficulties in access for local operations. The purpose of this study is to compare and evaluate the Equivalent Water Height (Ewh) from GRACE (Gravity Recovery And Climate Experiment) mission, to study the connection between water loading and vertical variations of the crust due to the hydrologic. In order to achieve this goal, the Ewh is compared with in-situ information from limnimeter. For the analysis it was computed the correlation coefficients, phase and amplitude of GRACE Ewh solutions and in-situ data, as well as the timing of periods of drought in different parts of the basin. The results indicated that vertical variations of the lithosphere due to water mass loading could reach 7 to 5 cm per year, in the sedimentary and flooded areas of the region, where water level variations can reach 10 to 8 m.

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In this study, the measurement of the concentration and size of particles and the identification of their sources were carried out at five orthopedic surgeries. The aerosol concentration and particle size distribution, ranging from 0.3 mu m 10 mu m, were measured and related to the type of indoor activity. The handling of surgical linen and gowns, handling of the patient, use of electrosurgical apparatus, use of a bone saw, handling of equipment, and cleaning of the room were identified as the most important sources of particles, with each of these activities posing different risks to the health of the patients and workers. The results showed that most of the particles were above 0.5 mu m and that there was a strong correlation among all particles of sizes above 1 mu m. Particles with diameters in the range of 0.3 mu m-0.5 mu m had a good correlation only with particles in the ranges of 0.5 mu m-1.0 mu m and 1.0 mu m-3.0 mu m in three of the surgeries analyzed. Findings led to the conclusion that most of the events responsible for generating aerosol particles in an orthopedic surgery room are brief, intermittent, and highly variable, thus requiring the use of specific instrumentation for their continuous identification and characterization.

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Intracellular peptides generated by the proteasome and oligopeptidases have been suggested to function in signal transduction and to improve insulin resistance in mice fed a high-caloric diet. The aim of this study was to identify specific intracellular peptides in the adipose tissue of Wistar rats that could be associated with the physiological and therapeutic control of glucose uptake. Using semiquantitative mass spectrometry and LC/MS/MS analyses, we identified ten peptides in the epididymal adipose tissue of the Wistar rats; three of these peptides were present at increased levels in rats that were fed a high-caloric Western diet (WD) compared with rats fed a control diet (CD). The results of affinity chromatography suggested that in the cytoplasm of epididymal adipose tissue from either WD or CD rats, distinctive proteins bind to these peptides. However, despite the observed increase in the WD animals, the evaluated peptides increased insulin-stimulated glucose uptake in 3T3-L1 adipocytes treated with palmitate. Thus, intracellular peptides from the adipose tissue of Wistar rats can bind to specific proteins and facilitate insulin-induced glucose uptake in 3T3-L1 adipocytes.