936 resultados para complement component C3
Resumo:
The complement system represents a cascade of serum proteins, which provide a major effector function in innate immunity. Recent studies have revealed that complement links innate and adaptive immunity via complement receptors CD21/CD35 in that it enhances the B cell memory response to noninfectious protein antigens introduced i.v. To examine the importance of complement for immune responses to virus infection in a peripheral tissue, we compared the B cell memory response of mice deficient in complement C3, C4, or CD21/CD35 with wild-type controls. We found that the deficient mice failed to generate a normal memory response, which is characterized by a reduction in IgG antibody and germinal centers. Thus, complement is important not only in the effector function of innate immunity but also in the stimulation of memory B cell responses to viral-infected cell antigens in both blood and peripheral tissues.
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The O2 and CO2 compensation points (O2 and CO2) of plants in a closed system depend on the ratio of CO2 and O2 concentrations in air and in the chloroplast and the specificities of ribulose bisphosphate carboxylase/oxygenase (Rubisco). The photosynthetic O2 is defined as the atmospheric O2 level, with a given CO2 level and temperature, at which net O2 exchange is zero. In experiments with C3 plants, the O2 with 220 ppm CO2 is 23% O2; O2 increases to 27% with 350 ppm CO2 and to 35% O2 with 700 ppm CO2. At O2 levels below the O2, CO2 uptake and reduction are accompanied by net O2 evolution. At O2 levels above the O2, net O2 uptake occurs with a reduced rate of CO2 fixation, more carbohydrates are oxidized by photorespiration to products of the C2 oxidative photosynthetic carbon cycle, and plants senesce prematurely. The CO2 increases from 50 ppm CO2 with 21% O2 to 220 ppm with 100% O2. At a low CO2/high O2 ratio that inhibits the carboxylase activity of Rubisco, much malate accumulates, which suggests that the oxygen-insensitive phosphoenolpyruvate carboxylase becomes a significant component of the lower CO2 fixation rate. Because of low global levels of CO2 and a Rubisco specificity that favors the carboxylase activity, relatively rapid changes in the atmospheric CO2 level should control the permissive O2 that could lead to slow changes in the immense O2 pool.
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Purpose: To investigate whether modification of liver complement factor H (CFH) production, by alteration of liver CFH Y402H genotype through liver transplantation (LT), influences the development of age-related macular degeneration (AMD). Design: Multicenter, cross-sectional study. Participants: We recruited 223 Western European patients ≥55 years old who had undergone LT ≥5 years previously. Methods: We determined AMD status using a standard grading system. Recipient CFH Y402H genotype was obtained from DNA extracted from recipient blood samples. Donor CFH Y402H genotype was inferred from recipient plasma CFH Y402H protein allotype, measured using enzyme-linked immunosorbent assays. This approach was verified by genotyping donor tissue from a subgroup of patients. Systemic complement activity was ascertained by measuring levels of plasma complement proteins using an enzyme-linked immunosorbent assay, including substrates (C3, C4), activation products (C3a, C4a, and terminal complement complex), and regulators (total CFH, C1 inhibitor). Main Outcome Measures: We evaluated AMD status and recipient and donor CFH Y402H genotype. Results: In LT patients, AMD was associated with recipient CFH Y402H genotype (P = 0.036; odds ratio [OR], 1.6; 95% confidence interval [CI], 1.0-2.4) but not with donor CFH Y402H genotype (P = 0.626), after controlling for age, sex, smoking status, and body mass index. Recipient plasma CFH Y402H protein allotype predicted donor CFH Y402H genotype with 100% accuracy (n = 49). Plasma complement protein or activation product levels were similar in LT patients with and without AMD. Compared with previously reported prevalence figures (Rotterdam Study), LT patients demonstrated a high prevalence of both AMD (64.6% vs 37.1%; OR, 3.09; P<0.001) and the CFH Y402H sequence variation (41.9% vs 36.2%; OR, 1.27; P = 0.014). Conclusions: Presence of AMD is not associated with modification of hepatic CFH production. In addition, AMD is not associated with systemic complement activity in LT patients. These findings suggest that local intraocular complement activity is of greater importance in AMD pathogenesis. The high AMD prevalence observed in LT patients may be associated with the increased frequency of the CFH Y402H sequence variation. © 2013 by the American Academy of Ophthalmology Published by Elsevier Inc.
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Mammalian C3 is a pivotal complement protein, encoded for by a single gene. In some vertebrate species multiple C3 isoforms are products of different C3 genes. The goal of this study was to determine whether multiple genes encode for shark C3. A protocol was developed for the isolation of mRNA from shark blood for the isolation of C3 cDNA clones. RT-PCR amplification of mRNA, using sense (GCGEQNM) and antisense (TWLTAYV) primers encoding conserved regions of human C3, yielded 21 clones. The C3-like clones isolated shared 97% similarity with each other and 40% similarity to human C3. RACE-PCR amplification of shark liver RNA, using gene specific primers, yielded products ranging from 1800bp to 3000bp. Deduced amino acid sequence, corresponding to 408bp of the 1800bp fragment, was obtained which showed 51% similarity to human C3. These results suggest that nurse shark C3 might be encoded for by more than one gene. ^
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Mammalian C3 is a complement protein which consists of an α chain (125kDa) and β chain (75kDa) held together by a disulfide bond. The a chain contains a conserved thiolester site which provides the molecule with opsonic properties. The protein is synthesized as a single pro-C3 molecule which is post-translationally modified. C3 genes have been identified in organisms from different phyla, however, the shark C3 gene remains to be cloned. Sequence data from the shark will contribute to understanding further the evolution of this key protein. To obtain additional sequence data for shark C3 genes a cDNA library was constructed and screened with a DIG-labeled C3 probe. Fifty clones were isolated and sequenced. Analysis identified four sequences that yielded positive alignments with C3 of a variety of organisms including human C3. Deduced amino acid sequence analysis confirmed a β/α cut site (RRRR), the CR3 and properdin binding sites, the catalytic histidine, and the reactive thiolester sequence. In the shark there are at least two C3-like genes as the gene sequence obtained is distinct from that previously described.
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In the current study, we have developed a magnetic resonance imaging-based method for non-invasive detection of complement activation in placenta and foetal brain in vivo in utero. Using this method, we found that anti-complement C3-targeted ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles bind within the inflamed placenta and foetal brain cortical tissue, causing a shortening of the T2* relaxation time. We used two mouse models of pregnancy complications: a mouse model of obstetrics antiphospholipid syndrome (APS) and a mouse model of preterm birth (PTB). We found that detection of C3 deposition in the placenta in the APS model was associated with placental insufficiency characterised by increased oxidative stress, decreased vascular endothelial growth factor and placental growth factor levels and intrauterine growth restriction. We also found that foetal brain C3 deposition was associated with cortical axonal cytoarchitecture disruption and increased neurodegeneration in the mouse model of APS and in the PTB model. In the APS model, foetuses that showed increased C3 in their brains additionally expressed anxiety-related behaviour after birth. Importantly, USPIO did not affect pregnancy outcomes and liver function in the mother and the offspring, suggesting that this method may be useful for detecting complement activation in vivo in utero and predicting placental insufficiency and abnormal foetal neurodevelopment that leads to neuropsychiatric disorders.
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Hoy se hace imperioso que la ética periodística se complemente con el tratamiento jurídico de la libertad de expresión. La precaución jurídica es la invitación a una visión integral de la ética profesional basada en la autorregulación y en el conocimiento de la teleología del periodismo
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Streptococcus sanguinis is a commensal pioneer colonizer of teeth and an opportunistic pathogen of infectious endocarditis. The establishment of S. sanguinis in host sites likely requires dynamic fitting of the cell wall in response to local stimuli. In this study, we investigated the two-component system (TCS) VicRK in S. sanguinis (VicRKSs), which regulates genes of cell wall biogenesis, biofilm formation, and virulence in opportunistic pathogens. A vicK knockout mutant obtained from strain SK36 (SKvic) showed slight reductions in aerobic growth and resistance to oxidative stress but an impaired ability to form biofilms, a phenotype restored in the complemented mutant. The biofilm-defective phenotype was associated with reduced amounts of extracellular DNA during aerobic growth, with reduced production of H2O2, a metabolic product associated with DNA release, and with inhibitory capacity of S. sanguinis competitor species. No changes in autolysis or cell surface hydrophobicity were detected in SKvic. Reverse transcription-quantitative PCR (RT-qPCR), electrophoretic mobility shift assays (EMSA), and promoter sequence analyses revealed that VicR directly regulates genes encoding murein hydrolases (SSA_0094, cwdP, and gbpB) and spxB, which encodes pyruvate oxidase for H2O2 production. Genes previously associated with spxB expression (spxR, ccpA, ackA, and tpK) were not transcriptionally affected in SKvic. RT-qPCR analyses of S. sanguinis biofilm cells further showed upregulation of VicRK targets (spxB, gbpB, and SSA_0094) and other genes for biofilm formation (gtfP and comE) compared to expression in planktonic cells. This study provides evidence that VicRKSs regulates functions crucial for S. sanguinis establishment in biofilms and identifies novel VicRK targets potentially involved in hydrolytic activities of the cell wall required for these functions.
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To characterize the recently described SCI1 (stigma/style cell cycle inhibitor 1) gene relationship with the auxin pathway, we have taken the advantage of the Arabidopsis model system and its available tools. At first, we have analyzed the At1g79200 T-DNA insertion mutants and constructed various transgenic plants. The loss- and gain-of-function plants displayed cell number alterations in upper pistils that were controlled by the amino-terminal domain of the protein. These data also confirmed that this locus holds the functional homolog (AtSCI1) of the Nicotiana tabacum SCI1 gene. Then, we have provided some evidences the auxin synthesis/signaling pathways are required for downstream proper AtSCI1 control of cell number: (a) its expression is downregulated in yuc2yuc6 and npy1 auxin-deficient mutants, (b) triple (yuc2yuc6sci1) and double (npy1sci1) mutants mimicked the auxin-deficient phenotypes, with no synergistic interactions, and (c) the increased upper pistil phenotype in these last mutants, which is a consequence of an increased cell number, was able to be complemented by AtSCI1 overexpression. Taken together, our data strongly suggests SCI1 as a component of the auxin signaling transduction pathway to control cell proliferation/differentiation in stigma/style, representing a molecular effector of this hormone on pistil development.
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The aim of this study was to develop a methodology using Raman hyperspectral imaging and chemometric methods for identification of pre- and post-blast explosive residues on banknote surfaces. The explosives studied were of military, commercial and propellant uses. After the acquisition of the hyperspectral imaging, independent component analysis (ICA) was applied to extract the pure spectra and the distribution of the corresponding image constituents. The performance of the methodology was evaluated by the explained variance and the lack of fit of the models, by comparing the ICA recovered spectra with the reference spectra using correlation coefficients and by the presence of rotational ambiguity in the ICA solutions. The methodology was applied to forensic samples to solve an automated teller machine explosion case. Independent component analysis proved to be a suitable method of resolving curves, achieving equivalent performance with the multivariate curve resolution with alternating least squares (MCR-ALS) method. At low concentrations, MCR-ALS presents some limitations, as it did not provide the correct solution. The detection limit of the methodology presented in this study was 50μgcm(-2).
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Biomass Refinery is a sequential of eleven thermochemical processes and one biological process with two initial basic treatments: prehydrolysis for lignocellulosics and low temperature conversion for biomass with medium-to-high content of lipids and proteins. The other ten processes are: effluent treatment plant, furfural plant, biodiesel plant, cellulignin dryer, calcination, fluidized bed boiler, authotermal reforming of cellulignin for syngas production, combined cycle of two-stroke low-speed engine or syngas turbine with fluidized bed boiler heat recovery, GTL technologies and ethanol from cellulose, prehydrolysate and syngas. Any kind of biomass such as wood, agricultural residues, municipal solid waste, seeds, cakes, sludges, excrements and used tires can be processed at the Biomass Refinery. Twelve basic products are generated such as cellulignin, animal feed, electric energy, fuels (ethanol, crude oil, biodiesel, char), petrochemical substitutes, some materials (ash, gypsum, fertilizers, silica, carbon black) and hydrogen. The technology is clean with recovery of energy and reuse of water, acid and effluents. Based on a holistic integration of various disciplines Biomass Refinery maximizes the simultaneous production of food, electric energy, liquid fuels and chemical products and some materials, achieving a competitive position with conventional and fossil fuel technologies, as well as payment capacity for biomass production. Biomass Refinery has a technical economical capability to complement the depletion of the conventional petroleum sources and to capture its GHGs resulting a biomass + petroleum ""green"" combination.
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Background: A relative friability to capture a sufficiently large patient population in any one geographic location has traditionally limited research into rare diseases. Methods and Results: Clinicians interested in the rare disease lymphangioleiomyomatosis (LAM) have worked with the LAM Treatment Alliance, the MIT Media Lab, and Clozure Associates to cooperate in the design of a state-of-the-art data coordination platform that can be used for clinical trials and other research focused on the global LAM patient population. This platform is a component of a set of web-based resources, including a patient self-report data portal, aimed at accelerating research in rare diseases in a rigorous fashion. Conclusions: Collaboration between clinicians, researchers, advocacy groups, and patients can create essential community resource infrastructure to accelerate rare disease research. The International LAM Registry is an example of such an effort.
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Managing schizophrenia has never been a trivial matter. Furthermore, while classical antipsychotics induce extrapyramidal side effects and hyperprolactinaemia, atypical antipsychotics lead to diabetes, hyperlipidaemia, and weight gain. Moreover, even with newer drugs, a sizable proportion of patients do not show significant improvement. Alstonine is an indole alkaloid identified as the major component of a plant-based remedy used in Nigeria to treat the mentally ill. Alstonine presents a clear antipsychotic profile in rodents, apparently with differential effects in distinct dopaminergic pathways. The aim of this study was to complement the antipsychotic profile of alstonine, verifying its effects on brain amines in mouse frontal cortex and striatum. Additionally, we examined if alstonine induces some hormonal and metabolic changes common to antipsychotics. HPLC data reveal that alstonine increases serotonergic transmission and increases intraneuronal dopamine catabolism. In relation to possible side effects, preliminary data suggest that alstonine does not affect prolactin levels, does not induce gains in body weight, but prevents the expected fasting-induced decrease in glucose levels. Overall, this study reinforces the proposal that alstonine is a potential innovative antipsychotic, and that a comprehensive understanding of its neurochemical basis may open new avenues to developing newer antipsychotic medications.
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Three-dimensional spectroscopy techniques are becoming more and more popular, producing an increasing number of large data cubes. The challenge of extracting information from these cubes requires the development of new techniques for data processing and analysis. We apply the recently developed technique of principal component analysis (PCA) tomography to a data cube from the center of the elliptical galaxy NGC 7097 and show that this technique is effective in decomposing the data into physically interpretable information. We find that the first five principal components of our data are associated with distinct physical characteristics. In particular, we detect a low-ionization nuclear-emitting region (LINER) with a weak broad component in the Balmer lines. Two images of the LINER are present in our data, one seen through a disk of gas and dust, and the other after scattering by free electrons and/or dust particles in the ionization cone. Furthermore, we extract the spectrum of the LINER, decontaminated from stellar and extended nebular emission, using only the technique of PCA tomography. We anticipate that the scattered image has polarized light due to its scattered nature.
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Aims. A model-independent reconstruction of the cosmic expansion rate is essential to a robust analysis of cosmological observations. Our goal is to demonstrate that current data are able to provide reasonable constraints on the behavior of the Hubble parameter with redshift, independently of any cosmological model or underlying gravity theory. Methods. Using type Ia supernova data, we show that it is possible to analytically calculate the Fisher matrix components in a Hubble parameter analysis without assumptions about the energy content of the Universe. We used a principal component analysis to reconstruct the Hubble parameter as a linear combination of the Fisher matrix eigenvectors (principal components). To suppress the bias introduced by the high redshift behavior of the components, we considered the value of the Hubble parameter at high redshift as a free parameter. We first tested our procedure using a mock sample of type Ia supernova observations, we then applied it to the real data compiled by the Sloan Digital Sky Survey (SDSS) group. Results. In the mock sample analysis, we demonstrate that it is possible to drastically suppress the bias introduced by the high redshift behavior of the principal components. Applying our procedure to the real data, we show that it allows us to determine the behavior of the Hubble parameter with reasonable uncertainty, without introducing any ad-hoc parameterizations. Beyond that, our reconstruction agrees with completely independent measurements of the Hubble parameter obtained from red-envelope galaxies.