T cells, adhesion molecules and modulation of apoptosis in visceral leishmaniasis glomerulonephritis

Background: Immune complex deposition is the accepted mechanism of pathogenesis of VL glomerulopathy however other immune elements may participate. Further in the present study, no difference was seen between immunoglobulin and C3b deposit intensity in glomeruli between infected and non-infected dogs thus T cells, adhesion molecules and parameters of proliferation and apoptosis were analysed in dogs with naturally acquired VL from an endemic area. The dog is the most important domestic reservoir of the protozoa Leishmania (L.) chagasi that causes visceral leishmaniasis (VL). The similarity of VL manifestation in humans and dogs renders the study of canine VL nephropathy of interest with regard to human pathology. Methods: From 55 dogs with VL and 8 control non-infected dogs from an endemic area, kidney samples were analyzed by immunohistochemistry for immunoglobulin and C3b deposits, staining for CD4+ and CD8+ T cells, ICAM-1, P-selectin and quantified using morphometry. Besides proliferation marker Ki-67, apoptosis markers M30 and TUNEL staining, and related cytokines TNF-alpha, IL-1 alpha were searched and quantified. Results: We observed similar IgG, IgM and IgA and C3b deposit intensity in dogs with VL and non-infected control dogs. However we detected the Leishmania antigen in cells in glomeruli in 54, CD4+ T cells in the glomeruli of 44, and CD8+ T cells in 17 of a total of 55 dogs with VL. Leishmania antigen was absent and T cells were absent/scarse in eight non-infected control dogs. CD 4+ T cells predominate in proliferative patterns of glomerulonephritis, however the presence of CD4+ and CD8+ T cells were not different in intensity in different patterns of glomerulonephritis. The expression of ICAM-1 and P-selectin was significantly greater in the glomeruli of infected dogs than in control dogs. In all patterns of glomerulonephritis the expression of ICAM-1 ranged from minimum to moderately severe and P-selectin from absent to severe. In the control animals the expression of these molecules ranged from absent to medium intensity. It was not observed any correlation between severity of the disease and these markers. There was a correlation between the number of Leishmania antigen positive cells and CD4+ T cells, and between the number of CD4+ T cells and CD8+ T cells. In dogs presenting different histopathological patterns of glomerulonephritis, parameters of proliferation and apoptosis were studied. Ki-67, a proliferative marker, was not detected locally, but fewer apoptotic cells and lower TNF-alpha expression were seen in infected animals than in non-infected controls. Conclusion: Immunopathogenic mechanisms of VL glomerulonephritis are complex and data in the present study suggest no clear participation of immunoglobulin and C3b deposits in these dogs but the possible migration of CD4+ T cells into the glomeruli, participation of adhesion molecules, and diminished apoptosis of cells contributing to determine the proliferative pattern of glomerulonephritis in VL.

In Vitro Adhesion of Streptococcus sanguinis to Dentine Root Surface After Treatment with Er:Yag Laser, Ultrasonic System, or Manual Curette

Objective: The purpose of this in vitro study was to evaluate the dentine root surface roughness and the adherence of Streptococcus sanguinis (ATCC 10556) after treatment with an ultrasonic system, Er:YAG laser, or manual curette. Background Data: Bacterial adhesion and formation of dental biofilm after scaling and root planing may be a challenge to the long-term stability of periodontal therapy. Materials and Methods: Forty flattened bovine roots were randomly assigned to one of the following groups: ultrasonic system (n = 10); Er:YAG laser (n = 10); manual curette (n = 10); or control untreated roots (n = 10). The mean surface roughness (Ra, mu m) of the specimens before and after exposure to each treatment was determined using a surface profilometer. In addition, S. sanguinis was grown on the treated and untreated specimens and the amounts of retained bacteria on the surfaces were measured by culture method. Results: All treatments increased the Ra; however, the roughest surface was produced by the curettes. In addition, the specimens treated with curettes showed the highest S. sanguinis adhesion. There was a significant positive correlation between roughness values and bacterial cells counts. Conclusion: S. sanguinis adhesion was the highest on the curette-treated dentine root surfaces, which also presented the greatest surface roughness.

RNA interference-mediated knockdown of CD49e (alpha 5 integrin chain) in human thymic epithelial cells modulates the expression of multiple genes and decreases thymocyte adhesion

Background: The thymus is a central lymphoid organ, in which bone marrow-derived T cell precursors undergo a complex process of maturation. Developing thymocytes interact with thymic microenvironment in a defined spatial order. A component of thymic microenvironment, the thymic epithelial cells, is crucial for the maturation of T-lymphocytes through cell-cell contact, cell matrix interactions and secretory of cytokines/chemokines. There is evidence that extracellular matrix molecules play a fundamental role in guiding differentiating thymocytes in both cortical and medullary regions of the thymic lobules. The interaction between the integrin alpha 5 beta 1 (CD49e/CD29; VLA-5) and fibronectin is relevant for thymocyte adhesion and migration within the thymic tissue. Our previous results have shown that adhesion of thymocytes to cultured TEC line is enhanced in the presence of fibronectin, and can be blocked with anti-VLA-5 antibody. Results: Herein, we studied the role of CD49e expressed by the human thymic epithelium. For this purpose we knocked down the CD49e by means of RNA interference. This procedure resulted in the modulation of more than 100 genes, some of them coding for other proteins also involved in adhesion of thymocytes; others related to signaling pathways triggered after integrin activation, or even involved in the control of F-actin stress fiber formation. Functionally, we demonstrated that disruption of VLA-5 in human TEC by CD49e-siRNA-induced gene knockdown decreased the ability of TEC to promote thymocyte adhesion. Such a decrease comprised all CD4/CD8-defined thymocyte subsets. Conclusion: Conceptually, our findings unravel the complexity of gene regulation, as regards key genes involved in the heterocellular cell adhesion between developing thymocytes and the major component of the thymic microenvironment, an interaction that is a mandatory event for proper intrathymic T cell differentiation.

Adhesion of Endodontic Sealers to Human Root Dentine Submitted to Different Surface Treatments

Objective: To evaluate the adhesion of the endodontic sealers Epiphany, Apexit Plus, and AH Plus to root canal dentin submitted to different surface treatments, by using the push-out test. Methods: One hundred twenty-eight root cylinders obtained from maxillary canines were embedded in acrylic resin, had the canals prepared, and were randomly assigned to four groups (n = 32), according to root dentin treatment: (I) distilled water (control), (II) 17% EDTAC, (III) 1% NaOCl and (IV) Er:YAG laser with 16-Hz, 400-mJ input (240-mJ output) and 0.32-J/cm(2) energy density. Each group was divided into four subgroups (n = 8) filled with Epiphany (either dispensed from the automix syringe supplied by the manufacturer or prepared by hand mixing), Apexit Plus, or AH Plus. Data (MPa) were analyzed by ANOVA and Tukey's test. Results: A statistically significant difference (p < 0.01) was found among the root-canal sealers, except for the Epiphany subgroups, which had statistically similar results to each other (p > 0.01): AH Plus (4.77 +/- 0.85), Epiphany/hand mixed (3.06 +/- 1.34), Epiphany/automix syringe (2.68 +/- 1.35), and Apexit Plus (1.22 +/- 0.33). A significant difference (p < 0.01) was found among the dentin surface treatments. The highest adhesion values were obtained with AH Plus when root dentin was treated with Er: YAG laser and 17% EDTAC. Epiphany sealer presented the lowest adhesion values to root dentin treated with 17% EDTAC. Conclusions: The resin-based sealers had different adhesive behaviors, depending on the treatment of root canal walls. The mode of preparation of Epiphany (automix syringe or hand mixing) did not influence sealer adhesion to root dentin.

Near-barrier quasielastic scattering as a sensitive tool to derive nuclear matter diffuseness

Quasielastic excitation functions for the (16,18)O + (60)Ni systems were measured at energies near and below the Coulomb barrier, at the backward angle theta(LAB) = 161 degrees. The corresponding quasielastic barrier distributions were derived. The data were compared with predictions from coupled channel calculations using a double-folding potential as a bare potential. For the (16)O-induced scattering, good agreement was obtained for the barrier distribution by using the projectile default nuclear matter diffuseness obtained from the Sao Paulo potential systematic, that is, 0.56 fm. However, for the (18)O-induced scattering, good agreement was obtained only when the projectile nuclear matter diffuseness was changed to 0.62 fm. Therefore, in this paper we show how near-barrier quasielastic scattering can be used as a sensitive tool to derive nuclear matter diffuseness.

Effect of sugarcane harvesting systems on soil carbon stocks in Brazil: an examination of existing data

Agricultural management practices that promote net carbon (C) accumulation in the soil have been considered as an important potential mitigation option to combat global warming. The change in the sugarcane harvesting system, to one which incorporates C into the soil from crop residues, is the focus of this work. The main objective was to assess and discuss the changes in soil organic C stocks caused by the conversion of burnt to unburnt sugarcane harvesting systems in Brazil, when considering the main soils and climates associated with this crop. For this purpose, a dataset was obtained from a literature review of soils under sugarcane in Brazil. Although not necessarily from experimental studies, only paired comparisons were examined, and for each site the dominant soil type, topography and climate were similar. The results show a mean annual C accumulation rate of 1.5 Mg ha-1 year-1 for the surface to 30-cm depth (0.73 and 2.04 Mg ha-1 year-1 for sandy and clay soils, respectively) caused by the conversion from a burnt to an unburnt sugarcane harvesting system. The findings suggest that soil should be included in future studies related to life cycle assessment and C footprint of Brazilian sugarcane ethanol.

Soil carbon stocks under no-tillage mulch-based cropping systems in the Brazilian Cerrado: An on-farm synchronic assessment

No-tillage mulch-based (NTM) cropping systems have been widely adopted by farmers in the Brazilian savanna region (Cerrado biome). We hypothesized that this new type of management should have a profound impact on soil organic carbon (SOC) at regional scale and consequently on climate change mitigation. The objective of this study was thus to quantify the SOC storage potential of NTM in the oxisols of the Cerrado using a synchronic approach that is based on a chronosequence of fields of different years under NTM. The study consisted of three phases: (1) a farm/cropping system survey to identify the main types of NTM systems to be chosen for the chronosequence; (2) a field survey to identify a homogeneous set of situations for the chronosequence and (3) the characterization of the chronosequence to assess the SOC storage potential. The main NTM system practiced by farmers is an annual succession of soybean (Glycine max)or maize (Zea mays) with another cereal crop. This cropping system covers 54% of the total cultivated area in the region. At the regional level, soil organic C concentrations from NTM fields were closely correlated with clay + silt content of the soil (r(2) = 0.64). No significant correlation was observed (r(2) = 0.07), however, between these two variables when we only considered the fields with a clay + silt content in the 500-700 g kg(-1) range. The final chronosequence of NTM fields was therefore based on a subsample of eight fields, within this textural range. The SOC stocks in the 0-30 cm topsoil layer of these selected fields varied between 4.2 and 6.7 kg C m(-2) and increased on average (r(2) = 0.97) with 0.19 kg C m(-2) year(-1). After 12 years of NTM management, SOC stocks were no longer significantly different from the stocks under natural Cerrado vegetation (p < 0.05), whereas a 23-year-old conventionally tilled and cropped field showed SOC stocks that were about 30% below this level. Confirming our hypotheses, this study clearly illustrated the high potential of NTM systems in increasing SOC storage under tropical conditions, and how a synchronic approach may be used to assess efficiently such modification on farmers` fields, identifying and excluding non desirable sources of heterogeneity (management, soils and climate). (C) 2010 Elsevier B.V. All rights reserved.

Do plant species influence soil CO(2) and N(2)O fluxes in a diverse tropical forest?

To test whether plant species influence greenhouse gas production in diverse ecosystems, we measured wet season soil CO(2) and N(2)O fluxes close to similar to 300 large (>35 cm in diameter at breast height (DBH)) trees of 15 species at three clay-rich forest sites in central Amazonia. We found that soil CO(2) fluxes were 38% higher near large trees than at control sites >10 m away from any tree (P < 0.0001). After adjusting for large tree presence, a multiple linear regression of soil temperature, bulk density, and liana DBH explained 19% of remaining CO(2) flux variability. Soil N(2)O fluxes adjacent to Caryocar villosum, Lecythis lurida, Schefflera morototoni, and Manilkara huberi were 84%-196% greater than Erisma uncinatum and Vochysia maxima, both Vochysiaceae. Tree species identity was the most important explanatory factor for N(2)O fluxes, accounting for more than twice the N(2)O flux variability as all other factors combined. Two observations suggest a mechanism for this finding: (1) sugar addition increased N(2)O fluxes near C. villosum twice as much (P < 0.05) as near Vochysiaceae and (2) species mean N(2)O fluxes were strongly negatively correlated with tree growth rate (P = 0.002). These observations imply that through enhanced belowground carbon allocation liana and tree species can stimulate soil CO(2) and N(2)O fluxes (by enhancing denitrification when carbon limits microbial metabolism). Alternatively, low N(2)O fluxes potentially result from strong competition of tree species with microbes for nutrients. Species-specific patterns in CO(2) and N(2)O fluxes demonstrate that plant species can influence soil biogeochemical processes in a diverse tropical forest.

Changes in soil organic carbon storage under different agricultural management systems in the Southwest Amazon Region of Brazil

The Cerrado and Amazon regions of Brazil are probably the largest agricultural frontier of the world, and Could be a sink or source for C depending on the net effect of land use change and subsequent management on soil organic C pools. We evaluated the effects of agricultural management systems on soil organic C (SOC) stocks in the Brazilian states of Rondonia and Mato Grosso, and derived regional specific factors for soil C stock change associated with different management systems. We used 50 observations (data points) in this study, including 42 dealing with annual cropping practices and 8 dealing with perennial cropping, and analyzed the data in linear mixed-effect models. No tillage (NT) systems in Cerrado areas increased SOC Storage by 1.08 +/- 0.06 relative to SOC stocks under native conditions, while SOC storage increased by a modest factor of 1.01 +/- 0.17 in Cerradao and Amazon Forest conditions. Full tillage (FT) had negative effect on SOC storage relative to NT, decreasing SOC stocks by a factor of 0.94 +/- 0.04. but did not significantly reduce SOC stocks relative to native levels when adopted in the Cerrado region. Perennial cropping had a minimal impact on SOC stocks, estimated at a factor Value of 0.98 +/- 0.14, suggesting these systems maintain about 98% of the SOC stock found under native vegetation. The results Suggest that NT adoption may be increasing SOC with land use change from native vegetation to cropland management in the Cerrado region of Brazil. (C) 2009 Elsevier B.V. All rights reserved.

Simulation of sugarcane residue decomposition and aboveground growth

Due to the worldwide increase in demand for biofuels, the area cultivated with sugarcane is expected to increase. For environmental and economic reasons, an increasing proportion of the areas are being harvested without burning, leaving the residues on the soil surface. This periodical input of residues affects soil physical, chemical and biological properties, as well as plant growth and nutrition. Modeling can be a useful tool in the study of the complex interactions between the climate, residue quality, and the biological factors controlling plant growth and residue decomposition. The approach taken in this work was to parameterize the CENTURY model for the sugarcane crop, to simulate the temporal dynamics of aboveground phytomass and litter decomposition, and to validate the model through field experiment data. When studying aboveground growth, burned and unburned harvest systems were compared, as well as the effect of mineral fertilizer and organic residue applications. The simulations were performed with data from experiments with different durations, from 12 months to 60 years, in Goiana, TimbaA(0)ba and Pradpolis, Brazil; Harwood, Mackay and Tully, Australia; and Mount Edgecombe, South Africa. The differentiation of two pools in the litter, with different decomposition rates, was found to be a relevant factor in the simulations made. Originally, the model had a basically unlimited layer of mulch directly available for decomposition, 5,000 g m(-2). Through a parameter optimization process, the thickness of the mulch layer closer to the soil, more vulnerable to decomposition, was set as 110 g m(-2). By changing the layer of mulch at any given time available for decomposition, the sugarcane residues decomposition simulations where close to measured values (R (2) = 0.93), contributing to making the CENTURY model a tool for the study of sugarcane litter decomposition patterns. The CENTURY model accurately simulated aboveground carbon stalk values (R (2) = 0.76), considering burned and unburned harvest systems, plots with and without nitrogen fertilizer and organic amendment applications, in different climates and soil conditions.

Soil Carbon Turnover Measurement by Physical Fractionation at a Forest-to-Pasture Chronosequence in the Brazilian Amazon

The effect of conversion from forest-to-pasture upon soil carbon stocks has been intensively discussed, but few studies focus on how this land-use change affects carbon (C) distribution across soil fractions in the Amazon basin. We investigated this in the 20 cm depth along a chronosequence of sites from native forest to three successively older pastures. We performed a physicochemical fractionation of bulk soil samples to better understand the mechanisms by which soil C is stabilized and evaluate the contribution of each C fraction to total soil C. Additionally, we used a two-pool model to estimate the mean residence time (MRT) for the slow and active pool C in each fraction. Soil C increased with conversion from forest-to-pasture in the particulate organic matter (> 250 mu m), microaggregate (53-250 mu m), and d-clay (< 2 mu m) fractions. The microaggregate comprised the highest soil C content after the conversion from forest-to-pasture. The C content of the d-silt fraction decreased with time since conversion to pasture. Forest-derived C remained in all fractions with the highest concentration in the finest fractions, with the largest proportion of forest-derived soil C associated with clay minerals. Results from this work indicate that microaggregate formation is sensitive to changes in management and might serve as an indicator for management-induced soil carbon changes, and the soil C changes in the fractions are dependent on soil texture.

Near infrared spectroscopy for soil bulk density assessment

P>Soil bulk density values are needed to convert organic carbon content to mass of organic carbon per unit area. However, field sampling and measurement of soil bulk density are labour-intensive, costly and tedious. Near-infrared reflectance spectroscopy (NIRS) is a physically non-destructive, rapid, reproducible and low-cost method that characterizes materials according to their reflectance in the near-infrared spectral region. The aim of this paper was to investigate the ability of NIRS to predict soil bulk density and to compare its performance with published pedotransfer functions. The study was carried out on a dataset of 1184 soil samples originating from a reforestation area in the Brazilian Amazon basin, and conventional soil bulk density values were obtained with metallic ""core cylinders"". The results indicate that the modified partial least squares regression used on spectral data is an alternative method for soil bulk density predictions to the published pedotransfer functions tested in this study. The NIRS method presented the closest-to-zero accuracy error (-0.002 g cm-3) and the lowest prediction error (0.13 g cm-3) and the coefficient of variation of the validation sets ranged from 8.1 to 8.9% of the mean reference values. Nevertheless, further research is required to assess the limits and specificities of the NIRS method, but it may have advantages for soil bulk density predictions, especially in environments such as the Amazon forest.

Total soil carbon and chemical attributes under different land uses in the Brazilian savanna

Total soil carbon and chemical attributes under different land uses in the Brazilian savanna. The Brazilian savanna region (Cerrado) is one of the largest cultivated areas of the world. The different land uses in the region can effectively change the quantities of soil organic matter and the cycling of nutrients. I-lie objective of this study was to evaluate the effect of different land use management systems on the relationship between soil organic carbon and the soil chemical attributes of a Red Latosol (Oxisol) under Cerrado in Rio Verde (Goias state). The treatments studied were native vegetation (cerrado), low-productivity pasture, conventional tillage with soybean, and no-tillage with soybean and maize. The smallest values for pH, available P, K, Ca and Mg were observed for the Cerradao treatment, even if the relatively high C levels increased the potential soil cation exchange capacity. The pasture, conventional tillage and no-tillage treatments showed higher K, Ca, Mg, available 13, and S concentrations in the soil. In the areas where soil tillage did not take place and lime and fertilizers were applied superficially, the stratification of the soil organic carbon provides the retention of the elements near to the surface, with significance correlations with the soil chemicals attributes.

Simulation of Soil Carbon Dynamics under Sugarcane with the CENTURY Model

Currently there is a trend for the expansion of the area cropped with sugarcane (Saccharum officinarum L.), driven by an increase in the world demand for biofuels, due to economical, environmental, and geopolitical issues. Although sugarcane is traditionally harvested by burning dried leaves and tops, the unburned, mechanized harvest has been progressively adopted. The use of process based models is useful in understanding the effects of plant litter in soil C dynamics. The objective of this work was to use the CENTURY model in evaluating the effect of sugarcane residue management in the temporal dynamics of soil C. The approach taken in this work was to parameterize the CENTURY model for the sugarcane crop, to simulate the temporal dynamics of soil C, validating the model through field experiment data, and finally to make predictions in the long term regarding soil C. The main focus of this work was the comparison of soil C stocks between the burned and unburned litter management systems, but the effect of mineral fertilizer and organic residue applications were also evaluated. The simulations were performed with data from experiments with different durations, from 1 to 60 yr, in Goiana and Timbauba, Pernambuco, and Pradopolis, Sao Paulo, all in Brazil; and Mount Edgecombe, Kwazulu-Natal, South Africa. It was possible to simulate the temporal dynamics of soil C (R(2) = 0.89). The predictions made with the model revealed that there is, in the long term, a trend for higher soil C stocks with the unburned management. This increase is conditioned by factors such as climate, soil texture, time of adoption of the unburned system, and N fertilizer management.

Effect of grassland management on soil carbon sequestration in Rondonia and Mato Grosso states, Brazil

Grassland management affects soil organic carbon (SOC) content and a variety of management options have been proposed to sequester carbon. However, studies conducted in Brazilian pastures have shown divergent responses for the SOC depending on management practices. Our objective was to evaluate the effects of management on SOC stocks in grasslands of the Brazilian states of Rondonia and Mato Grosso, and to derive region-specific factors for soil C stock change associated with different management conditions. Compared to SOC stocks in native vegetation, degraded grassland management decreased SOC by a factor of 0.91 +/- 0.14, nominal grassland management reduced SOC stock for Oxisols by a relatively small factor of 0.99 +/- 0.08, whereas, SOC storage increased by a factor of 1.24 +/- 0.07 with nominal management for other soil types. Improved grassland management on Oxisols increased SOC storage by 1.19 +/- 0.07, relative to native stocks, but there were insufficient data to evaluate the impact of improved grassland management for other soil types. Using these results, we also evaluated the potential for grassland management to sequester or emit C to the atmosphere, and found that degraded grassland management decreased stocks by about 0.27-0.28 Mg C ha(-1) yr(-1); nominal management on Oxisols decreased C at a rate of 0.03 Mg C ha(-1) yr(-1), while nominal management on others soil types and improved management on Oxisols increased stocks by 0.72 Mg C ha(-1) yr(-1) and 0.61 Mg C ha(-1) yr(-1), respectively. Therefore, when well managed or improved, grasslands in Rondonia and Mato Grosso states have the potential to sequester C. (c) 2008 Elsevier B.V. All rights reserved.