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排序方式: 共有209条查询结果,搜索用时 15 毫秒
121.
Alessandro Marins-Dos-Santos Bianca Perdigo Olivieri Rafaella Ferreira-Reis Juliana de Meis Andrea Alice Silva Tania C. de Araújo-Jorge Joseli Lannes-Vieira Vinicius Cotta-de-Almeida 《PLoS neglected tropical diseases》2020,14(12)
CD8 T cells are regarded as pivotal players in both immunoprotection and immunopathology following Trypanosoma cruzi infection. Previously, we demonstrated the expansion of CD8+ T lymphocytes in the spleen of T. cruzi-infected mice under treatment with benznidazole (N-benzyl-2-nitroimidazole acetamide; Bz), a drug available for clinical therapy. This finding underlies the concept that the beneficial effects of Bz on controlling acute T. cruzi infection are related to a synergistic process between intrinsic trypanocidal effect and indirect triggering of the active immune response. In the present study, we particularly investigated the effect of Bz treatment on the CD8+ T cell subset following T. cruzi infection. Herein we demonstrated that, during acute T. cruzi infection, Bz treatment reduces and abbreviates the parasitemia, but maintains elevated expansion of CD8+ T cells. Within this subset, a remarkable group of CD8low cells was found in both Bz-treated and non-treated infected mice. In Bz-treated mice, early pathogen control paralleled the lower frequency of recently activated CD8low cells, as ascertained by CD69 expression. However, the CD8low subset sustains significant levels of CD44highCD62Llow and CD62LlowT-bethigh effector memory T cells, in both Bz-treated and non-treated infected mice. These CD8low cells also comprise the main group of spontaneous interferon (IFN)-γ-producing CD8+ T cells. Interestingly, following in vitro anti-CD3/CD28 stimulation, CD8+ T cells from Bz-treated T. cruzi-infected mice exhibited higher frequency of IFN-γ+ cells, which bear mostly a CD8low phenotype. Altogether, our results point to the marked presence of CD8low T cells that arise during acute T. cruzi infection, with Bz treatment promoting their significant expansion along with a potential effector program for high IFN-γ production. 相似文献
122.
de Meis J Mendes-da-Cruz DA Farias-de-Oliveira DA Corrêa-de-Santana E Pinto-Mariz F Cotta-de-Almeida V Bonomo A Savino W 《Microbes and infection / Institut Pasteur》2006,8(1):221-231
It is currently accepted that experimental acute infection by Trypanosoma cruzi promotes changes in secondary lymphoid organs, with general T and B lymphocyte polyclonal activation. Here we show that mesenteric lymph nodes (MLN) of acutely infected mice show severe atrophy due to extensive lymphocyte apoptosis. Accordingly, clusters of apoptotic cells are detected in the initial phase of infection in MLN but not in subcutaneous nodes. Moreover, such atrophy is independent of the infection route, parasite load or the mouse strain used. Studies in Fas-L deficient (BALB gld/gld+/+) and in TNF type 1 receptor (p55-/-) knockout mice indicate that both molecules are involved in MLN atrophy: Fas-L participates in cell death of CD4+ as well as B lymphocytes, whereas the TNF type 1 receptor is important for the apoptosis of CD4+ and CD8+ T lymphocytes. In contrast, perforin does not play a role, as lymph nodes from perforin-deficient mice do not behave differently from the corresponding wild types. Our data support the concept that, even in a systemic infection, differential (even opposing) responses can be found in different lymph node chains. 相似文献
123.
de Meis L Arruda AP da Costa RM Benchimol M 《The Journal of biological chemistry》2006,281(24):16384-16390
In brown adipose tissue (BAT) adrenaline promotes a rise of the cytosolic Ca(2+) concentration from 0.05 up to 0.70 mum. It is not known how the rise of Ca(2+) concentration activates BAT thermogenesis. In this report we compared the effects of Ca(2+) in BAT and liver mitochondria. Using electron microscopy and immunolabeling we identified a sarco/endoplasmic reticulum (ER) Ca(2+)-ATPase bound to the inner membrane of BAT mitochondria. A Ca(2+)-dependent ATPase activity was detected in BAT mitochondria when the respiratory substrates malate and pyruvate were included in the medium. ATP and Ca(2+) enhanced the amount of heat produced by BAT mitochondria during respiration. The Ca(2+) concentration needed for half-maximal activation of the ATPase activity and rate of heat production were the same and varied between 0.1 and 0.2 mum. Heat production was partially inhibited by the proton ionophore carbonyl cyanide p-trifluoromethoxyphenylhydrazone and abolished by thapsigargin, a specific ER Ca(2+)-ATPase inhibitor, and by both rotenone and KCN, two substances that inhibit the electron transfer trough the mitochondrial cytochrome chain. In liver mitochondria Ca(2+) did not stimulate the ATPase activity nor increase the rate of heat production. Thapsigargin had no effect on liver mitochondria. In conclusion, this is the first report of a Ca(2+)-ATPase in mitochondria that is BAT-specific and can generate heat in the presence of Ca(2+) concentrations similar to those noted in the cell during adrenergic stimulation. 相似文献
124.
Balajee SA de Valk HA Lasker BA Meis JF Klaassen CH 《Journal of microbiological methods》2008,73(3):252-256
A microsatellite assay based on short tandem repeats (STRAf) has been recently described as a discriminatory, high throughput assay for fingerprinting Aspergillus fumigatus isolates. However, the STRAf assay has not been tested for its utility in outbreak settings where it is critical to distinguish clonal clusters from genetically unrelated genotypes. In the present study, employing a panel of epidemiologically linked A. fumigatus isolates obtained from 6 different outbreaks of invasive aspergillosis (IA), we demonstrate that the STRAf assay can be a valuable molecular tool to support epidemiological investigations. We also report for the first time the detection of microvariation events in the A. fumigatus population studied. 相似文献
125.
We calculate, using the first law of thermodynamics, the membrane heat fluxes during active transport of Ca2+ in the Ca2+-ATPase in leaky and intact vesicles, during ATP hydrolysis or synthesis conditions. The results show that the vesicle interior
may cool down during hydrolysis and Ca2+-uptake, and heat up during ATP synthesis and Ca2+-efflux. The heat flux varies with the SERCA isoform. Electroneutral processes and rapid equilibration of water were assumed.
The results are consistent with the second law of thermodynamics for the overall processes. The expression for the heat flux
and experimental data, show that important contributions come from the enthalpy of hydrolysis for the medium in question,
and from proton transport between the vesicle interior and exterior. The analysis give quantitative support to earlier proposals
that certain, but not all, Ca2+-ATPases, not only act as Ca2+-pumps, but also as heat pumps. It can thus help explain why SERCA 1 type enzymes dominate in tissues where thermal regulation
is important, while SERCA 2 type enzymes, with their lower activity and better ability to use the energy from the reaction
to pump ions, dominate in tissues where this is not an issue.
相似文献
Signe KjelstrupEmail: |
126.
Phosphorylation of the membranous protein of the sarcoplasmic reticulum. Inhibition by Na + and K + 总被引:1,自引:0,他引:1
L De Meis 《Biochemistry》1972,11(13):2460-2465
127.
Millisecond mixing and quenching experiments demonstrate an apparent t1/2 for the labeling of phosphorylated sarcoplasmic reticulum ATPase by 32Pi at pH 6 and 30 degrees C of 30 to 40 ms. Under the same conditions, the rate of exchange of water oxygens with inorganic phosphate (Pi) is about 40 mol of H2O exchanged with Pi per 10(6) g of protein per s. Theoretical equations are developed for the expected 32P-labeling pattern given various comparative rates of flux between Pi and the Michaelis complex and between the Michaelis complex and phosphorylated enzyme. The results show that the rapid reversal of the formation of the phosphorylated enzyme is a major source of the oxygen exchange and are consistent with such reversal being the only source. 相似文献
128.
R. Devanathan L. R. Corrales W. J. Weber A. Chartier C. Meis 《Molecular simulation》2013,39(12-13):1069-1077
Defect production and amorphisation due to energetic uranium recoils in zircon (ZrSiO4), which is a promising ceramic nuclear waste form, is studied using molecular dynamics (MD) simulations with a partial charge model. An algorithm that distinguishes between undamaged crystal, crystalline defects and amorphous regions is used to develop a fundamental understanding of the primary damage state. The amorphous cascade core is separated from the surrounding crystal by a defect-rich region. Small, chemically inhomogeneous amorphous clusters are also produced around the core. The amorphous regions consist of under-coordinated Zr and polymerised Si leading to amorphisation and phase separation on a nanometer scale into Zr- and Si-rich regions. This separation could play an important role in the experimentally observed formation of nanoscale ZrO2 in ZrSiO4 irradiated at elevated temperatures. 相似文献
129.
Iain D. M. Gunn Sebastian Meis Stephen C. Maberly Bryan M. Spears 《Hydrobiologia》2014,737(1):309-320
Loch Flemington is a shallow lake of international conservation and scientific importance. In recent decades, its status has declined as a result of eutrophication and the establishment of non-native invasive aquatic macrophytes. As previous research had identified the lake bed sediments as an important source of phosphorus (P), the P-capping material Phoslock® was applied to improve water quality. This article documents the responses of the aquatic macrophyte community by comparing data collected between 1988 and 2011. Summer water-column total P concentrations decreased significantly and water clarity increased following treatment. Aquatic plant colonisation depth increased and plant coverage of the lake bed extended. However, the submerged vegetation remained dominated by the non-native Elodea canadensis Michx. Aquatic macrophyte community metrics indicated no significant change in trophic status. Species richness and the number of ‘natural’ eutrophic characteristic species remained broadly similar with no records of rare species of conservation interest. Loch Flemington is still classified as being in ‘unfavourable no change’ condition based on its aquatic macrophytes despite the water quality improvements. The implications of these results are discussed in relation to the future management of Loch Flemington and in the wider context of trying to improve our understanding of lake restoration processes. 相似文献
130.
In the presence of hexokinase, vesicles derived from the sarcoplasmic reticulum of skeletal muscle are able to accumulate Ca2+ in a medium containing ADP and glucose 6-phosphate. No significant Ca2+ uptake is observed if one of these components is omitted from the assay medium. Due to its high affinity for ATP, the Ca(2+)-ATPase can use the very low concentrations of ATP formed from glucose 6-phosphate and ADP to form a Ca2+ gradient. This finding indicates that glucose 6-phosphate and hexokinase can be used as an ATP-regenerating system. The Ca2+ uptake supported by glucose 6-phosphate and ADP is inhibited by glucose and D-xylose. Half-maximal inhibition is observed in the presence of 0.4 mM glucose and 100 mM D-xylose. The transport ratio (Ca2+ transported:substrate utilized) is the same for glucose 6-phosphate and ATP. The Ca2+ gradient formed when glucose 6-phosphate and ADP are the substrates can be used to synthesize ATP from ADP and Pi. The concentration of ATP formed after reversal of the Ca2+ pump is much higher than that expected from direct equilibration of the reaction between glucose 6-phosphate and ADP. 相似文献