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91.
R A Cunha M D Constantino E Fonseca J A Ribeiro 《European journal of biochemistry》2001,268(10):2939-2947
Unsaturated free fatty acids and adenosine operate two neuromodulatory systems with opposite effects on neuronal function. Here, we tested if fatty acids controlled inhibitory adenosine A1 receptors. Arachidonate (AA, 10 microM) decreased the Bmax of an A1 receptor agonist, (R)-[3H]phenylisopropyladenosine (PIA; from 812 to 267 fmol x mg(-1) protein), and antagonist, [3H]1,3-dipropyl-8-cyclopentylxanthine (DPCPX; from 994 to 311 fmol x mg(-1) protein) and decreased the Kd of [3H]PIA (from 1.20 to 0.57 nM) binding to brain membranes of young adult rats (2 months old), these effects being mimicked by other cis but not trans unsaturated or saturated fatty acids. AA (10 microM) increased the potency of the A1 receptor agonist, 2-chloroadenosine to inhibit hippocampal synaptic transmission in young adult rats (EC50 decreased from 337 to 237 nM), which may constitute a safety feedback mechanism to control AA-induced neurotoxicity. Upon aging, there were increased free fatty acid levels and a concomitant decreased density of A1 receptors. This was more marked in hippocampal nerve terminals of aged rats (24 months old) and may be the determinant factor contributing to the lower potency of 2-choloroadenosine in aged rats (EC50 = 955 nM), in spite of the decreased Kd of PIA binding upon aging. The effects of AA on A1 receptor binding were attenuated upon aging, AA being devoid of effects in aged rats. Accordingly, AA (10 microM) failed to modify the potency of 2-choloroadenosine in aged rats (EC50 = 997 nM). However, albumin, which quenches free fatty acids, increased A1 receptor density by 65% and 2-chloroadenosine potency (EC50 = 703 nM) in aged rats, suggesting that the increased fatty acids levels in aged rats may contribute to the decreased potency of A1 receptor agonists in aged rats. Also, the observed saturation of the control by AA of A1 receptors may contribute to the decreased adaptability of neuromodulation to different firing conditions in aged rats. 相似文献
92.
Hugo Teixeira Gomes Patrícia Monah Cunha Bartos Clovis Oliveira Silva Lourdes Isabel Velho do Amaral Jonny Everson Scherwinski-Pereira 《Plant Growth Regulation》2014,74(2):199-208
In this study, the different stages of somatic embryogenesis (SE) of the African oil palm (Elaeis guineensis Jacq.) were characterized biochemically. The total soluble sugars, starch, total free amino acids, and total proteins were extracted, identified and quantified at various stages of embryogenesis: zygotic embryos (initial explants), primary calluses, embryogenic calluses, calluses with pro-embryos, globular embryos, differentiated somatic embryos, and regenerated plants. It was found that at the onset of induction of SE, the level of soluble sugars in the tissues of the explants fell by half. During this period, the total soluble sugars present in the cultures consisted basically of glucose and fructose. In the process of regeneration and maturation, the concentrations of soluble sugars gradually increased, reaching the highest values in the last two stages of development. At this stage, the disaccharide sucrose accounts for more than 80 % of the composition of total soluble sugars in the explants. Compared to starch, we found that the concentrations thereof in developing tissues are inversely proportional to that of soluble sugars virtually throughout embryogenic development. As for free amino acids, we found that after 30 days of induction until formation of the embryogenic calluses, there is an accentuated synthesis of total free amino acids in the explant tissue. In this stage, there was a significant increase in the levels of alanine and serine in the tissues. However, after the formation of the embryogenic calluses, the levels of total free amino acids present in the cultures become stabile and remain constant until the end of cultivation. Similar results were found for total protein, which also showed a significant increase at the onset of induction, undergoing slight changes during the remainder of the cultivation. 相似文献
93.
Wetlands are ecosystems commonly characterized by elevated levels of dissolved organic carbon (DOC), and although they cover a surface area less than 2 % worldwide, they are an important carbon source representing an estimated 15 % of global annual DOC flux to the oceans. Because of their unique hydrological characteristics, fire can be an important ecological driver in pulsed wetland systems. Consequently, wetlands may be important sources not only of DOC but also of products derived from biomass burning, such as dissolved black carbon (DBC). However, the biogeochemistry of DBC in wetlands has not been studied in detail. The objective of this study is to determine the environmental dynamics of DBC in different fire-impacted wetlands. An intensive, 2-year spatial and temporal dynamics study of DBC in a coastal wetland, the Everglades (Florida) system, as well as one-time sampling surveys for the other two inland wetlands, Okavango Delta (Botswana) and the Pantanal (Brazil), were reported. Our data reveal that DBC dynamics are strongly coupled with the DOC dynamics regardless of location, season or recent fire history. The statistically significant linear regression between DOC and DBC was applied to estimate DBC fluxes to the coastal zone through two main riverine DOC export routes in the Everglades ecosystem. The presence of significant amounts of DBC in these three fire-impacted ecosystems suggests that sub-tropical wetlands could represent an important continental-ocean carrier of combustion products from biomass burning. The discrimination of DBC molecular structure (i.e. aromaticity) between coastal and terrestrial samples, and between samples collected in wet and dry season, suggests that spatially-significant variation in DBC source strength and/or degree of degradation may also influence DBC dynamics. 相似文献
94.
95.
Luiza Pinheiro Carla Ivo Brito Valéria Cataneli Pereira Adilson de Oliveira Carlos Henrique Camargo Maria de Lourdes Ribeiro de Souza da Cunha 《Memórias do Instituto Oswaldo Cruz》2014,109(7):871-878
This study aimed to correlate the presence of ica genes, biofilm
formation and antimicrobial resistance in 107 strains of Staphylococcus
epidermidis isolated from blood cultures. The isolates were analysed to
determine their methicillin resistance, staphylococcal cassette chromosome
mec (SCCmec) type, ica genes
and biofilm formation and the vancomycin minimum inhibitory concentration (MIC) was
measured for isolates and subpopulations growing on vancomycin screen agar. The
mecA gene was detected in 81.3% of the S.
epidermidis isolated and 48.2% carried SCCmec type III.
The complete icaADBC operon was observed in 38.3% of the isolates;
of these, 58.5% produced a biofilm. Furthermore, 47.7% of the isolates grew on
vancomycin screen agar, with an increase in the MIC in 75.9% of the isolates.
Determination of the MIC of subpopulations revealed that 64.7% had an MIC ≥ 4 μg
mL-1, including 15.7% with an MIC of 8 μg mL-1 and 2% with
an MIC of 16 μg mL-1. The presence of the icaADBC operon,
biofilm production and reduced susceptibility to vancomycin were associated with
methicillin resistance. This study reveals a high level of methicillin resistance,
biofilm formation and reduced susceptibility to vancomycin in subpopulations of
S. epidermidis. These findings may explain the selection of
multidrug-resistant isolates in hospital settings and the consequent failure of
antimicrobial treatment. 相似文献
96.
Bosco Christiano Maciel da Silva Maria Fernanda Rios Grassi Raimundo Coutinho Rita Elizabeth Moreira Mascarenhas Viviana Nilla Olavarria Adriana Coutinho-Borgo Jorge Kalil Edecio Cunha Neto Simone Gon?alves Fonseca 《Memórias do Instituto Oswaldo Cruz》2014,109(8):999-1004
The interferon (IFN)-γ response to peptides can be a useful diagnostic marker of
Mycobacterium tuberculosis (MTB) latent infection. We identified promiscuous and
potentially protective CD4+ T-cell epitopes from the most conserved
regions of MTB antigenic proteins by scanning the MTB antigenic proteins GroEL2,
phosphate-binding protein 1 precursor and 19 kDa antigen with the TEPITOPE algorithm.
Seven peptide sequences predicted to bind to multiple human leukocyte antigen
(HLA)-DR molecules were synthesised and tested with IFN-γ enzyme-linked immunospot
(ELISPOT) assays using peripheral blood mononuclear cells (PBMCs) from 16 Mantoux
tuberculin skin test (TST)-positive and 16 TST-negative healthy donors. Eighty-eight
percent of TST-positive donors responded to at least one of the peptides, compared to
25% of TST-negative donors. Each individual peptide induced IFN-γ production by PBMCs
from at least 31% of the TST-positive donors. The magnitude of the response against
all peptides was 182 ± 230 x 106 IFN-γ spot forming cells (SFC) among
TST-positive donors and 36 ± 62 x 106 SFC among TST-negative donors (p =
0.007). The response to GroEL2 (463-477) was only observed in the TST-positive group.
This combination of novel MTB CD4 T-cell epitopes should be tested in a larger cohort
of individuals with latent tuberculosis (TB) to evaluate its potential to diagnose
latent TB and it may be included in ELISPOT-based IFN-γ assays to identify
individuals with this condition. 相似文献
97.
Yasmin Silva Rizk Alice Fischer Marillin de Castro Cunha Patrik Oening Rodrigues Maria Carolina Silva Marques Maria de Fátima Cepa Matos M?nica Cristina Toffoli Kadri Carlos Alexandre Carollo Carla Cardozo Pinto de Arruda 《Memórias do Instituto Oswaldo Cruz》2014,109(8):1050-1056
This study is the first phytochemical investigation of Selaginella sellowii
and demonstrates the antileishmanial activity of the hydroethanolic extract
from this plant (SSHE), as well as of the biflavonoids amentoflavone and
robustaflavone, isolated from this species. The effects of these substances were
evaluated on intracellular amastigotes of Leishmania (Leishmania)
amazonensis, an aetiological agent of American cutaneous leishmaniasis.
SSHE was highly active against intracellular amastigotes [the half maximum inhibitory
concentration (IC50) = 20.2 µg/mL]. Fractionation of the extract led to the isolation
of the two bioflavonoids with the highest activity: amentoflavone, which was about
200 times more active (IC50 = 0.1 μg/mL) and less cytotoxic than SSHE (IC50 = 2.2 and
3 μg/mL, respectively on NIH/3T3 and J774.A1 cells), with a high selectivity index
(SI) (22 and 30), robustaflavone, which was also active against L.
amazonensis (IC50 = 2.8 µg/mL), but more cytotoxic, with IC50 = 25.5
µg/mL (SI = 9.1) on NIH/3T3 cells and IC50 = 3.1 µg/mL (SI = 1.1) on J774.A1 cells.
The production of nitric oxide (NO) was lower in cells treated with amentoflavone
(suggesting that NO does not contribute to the leishmanicidal mechanism in this
case), while NO release was higher after treatment with robustaflavone. S.
sellowii may be a potential source of biflavonoids that could provide
promising compounds for the treatment of cutaneous leishmaniasis. 相似文献
98.
Laura Azeredo Miranda Mota Jo?o Roberto Neto Ver?nica Gomes Monteiro Caroliny Samary Silva Lobato Marco Antonio de Oliveira Maura da Cunha Heloisa D’ávila Sérgio Henrique Seabra Patrícia Torres Bozza Renato Augusto DaMatta 《Memórias do Instituto Oswaldo Cruz》2014,109(6):767-774
Lipid bodies [lipid droplets (LBs)] are lipid-rich organelles involved in lipid
metabolism, signalling and inflammation. Recent findings suggest a role for LBs in
host response to infection; however, the potential functions of this organelle
in Toxoplasma gondii infection and how it alters macrophage
microbicidal capacity during infection are not well understood. Here, we investigated
the role of host LBs in T. gondii infection in mouse peritoneal
macrophages in vitro. Macrophages cultured with mouse serum (MS) had higher numbers
of LBs than those cultured in foetal bovine serum and can function as a model to
study the role of LBs during intracellular pathogen infection. LBs were found in
association with the parasitophorous vacuole, suggesting that T. gondii
may benefit from this lipid source. Moreover, increased numbers of
macrophage LBs correlated with high prostaglandin E2 (PGE2) production and decreased
nitric oxide (NO) synthesis. Accordingly, LB-enriched macrophages cultured with MS
were less efficient at controlling T. gondii growth. Treatment of
macrophages cultured with MS with indomethacin, an inhibitor of PGE2 production,
increased the microbicidal capacity against T. gondii. Collectively,
these results suggest that culture with MS caused a decrease in microbicidal activity
of macrophages against T. gondii by increasing PGE2 while lowering
NO production. 相似文献
99.
100.
Fernanda Keiko Iwano Magno Antonio Patto Ramalho Indalécio Cunha Vieira Júnior Ângela de Fátima Barbosa Abreu 《Journal of Phytopathology》2014,162(5):277-283
Disease severity assessment by means of a scoring scale, especially for angular leaf spot (Pseudocercospora griseola) in common bean, is hindered in experiments for assessment of progenies and/or breeding lines due to lack of uniformity of occurrence of the pathogens and segregation within progenies. The purpose of this study was to estimate the efficiency of the use of one plant per plot in assessing the severity of angular leaf spot in experiments for assessment of progenies and/or breeding lines in the common bean crop. To that end, two experimental strategies were used – one of them using one plant per plot and another using a standard size plot (SPP) (2–4‐m length rows). The experiments were conducted in the period from November 2011 to May 2012 in the municipalities of Lavras and Lambari, state of Minas Gerais, Brazil. Forty‐one lines from the breeding programme of the Universidade Federal de Lavras (UFLA) and from other research institutions were assessed, which differed in regard to their degree of susceptibility to P. griseola. The lines were assessed in regard to the severity of said disease using a five‐degree diagrammatic scale. In all the one plant per plot experiments, severity scores of angular leaf spot from the beginning of its occurrence, and later in intervals ranging from 7 to 12 days, were obtained. In the experiment with the SPP, assessment was made a few days prior to grain harvest. Estimates of the correlations between severity scores and grain yield (GY) were mostly of small magnitude. There was good coincidence between the lines classified as more resistant or more susceptible to the pathogen under the two conditions. 相似文献