134 resultados para polyphosphate


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Química - IQ

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Objectives: To evaluate the anti-erosive potential of solutions containing sodium fluoride (NaF, 225 ppm F) and different film-forming agents.Methods: In Phase 1, hydroxyapatite crystals were pre-treated with solutions containing NaF (F), linear sodium polyphosphate (LPP), sodium pyrophosphate tetrabasic (PP), sodium tripolyphosphate (STP), sodium caseinate (SC), bovine serum albumin (BSA), stannous chloride (Sn) and some combinations thereof. Deionized water was the control (C). The pH-stat method was used to evaluate hydroxyapatite dissolution. In Phase 2, the most effective solutions were tested in two independent experiments. Both consisted of an erosion-remineralization cycling model using enamel and dentine specimens with three solution treatments per day. In Phase 2a, the challenge was performed with 0.3% citric acid (pH = 3.8). In Phase 2b, 1% citric acid (pH = 2.4) was used. Hard tissue surface loss was determined profilometrically. Data were analyzed with two-way ANOVA and Tukey tests.Results: In Phase 1, F, LPP, Sn and some of their combinations caused the greatest reduction in hydroxyapatite dissolution. In Phase 2a, C showed the highest enamel loss, followed by LPP. There were no differences between all other groups. In Phase 2b: (F + LPP + Sn) < (F + LPP) = (F + Sn) < (F) = (LPP + Sn) < (LPP) < (Sn) < C. For dentine, in both experiments, only the fluoride-containing groups showed lower surface loss than C, except for LPP + Sn in 2a.Conclusions: F, Sn, LPP reduced enamel erosion, this effect was enhanced by their combination under highly erosive conditions. For dentine, the F-containing groups showed similar protective effect.Clinical significance: The addition of LPP and/or Sn can improve the fluoride solution protection against erosion of enamel but not of dentine. (C) 2015 Elsevier Ltd. All rights reserved.

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Organic- inorganic hybrid (HOI) are materials prepared with the combination of inorganic and organic components. The properties of a hybrid material are unique, not being the sum of each individual component added. This occurs because there is a synergism that depends of the chemical nature of organic and inorganic components, of the size and morphology of their domains. The sodium carboxymethylcellulose (CMC) it's an anionic polymer obtained of the cellulose, very soluble in water in which forms both solutions themselves and gels. The sodium polyphosphate (NaPO3)n, known commercially as Graham Salt is the only polyphosphate soluble in water, and it's the polyphosphate with the longest chain. At the present work it was prepared and characterized new phosphate organic- inorganic hybrids films of carboxymethylcellulose / sodium phosphate and luminescent films of CMC/NaPO3 doped with europium chloride (EuCl3). The films where prepared in several proportions. At first, it was set the amount of water to be used and the amount of carboxymethylcellulose, changing the concentrations of sodium polyphosphate and europium chloride. After pre-establishing concentrations, for each film, the components were submitted to constant agitation and subsequent drying. The inorganic-organic hybrid films were characterized by, TG, DR-X, DMA, FT-IR, UV-Vis-NIR, RMN 31P e 13C and at last, a study of luminescence was made. The hybrid films obtained are transparent and macroscopically homogeneous, however, the MET measures showed the formation of micro-islands of polyphosphate along the material, this fact indicates a bigger fragmentation of the films and this is verified by DMA analysis which shows a smaller resistance of the film with the increase of the concentration of phosphate. Both spectrum FT-IR and RMN analysis of the films, don't show the formation of new bands of their precursors, CMC e NaPO3,....

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Triatoma matogrossensis is a Hemiptera that belongs to the oliveirai complex, a vector of Chagas' disease that feeds on vertebrate blood in all life stages. Hematophagous insects' salivary glands (SGs) produce potent pharmacologic compounds that counteract host hemostasis, including anticlotting, antiplatelet, and vasodilatory molecules. Exposure to T. matogrossensis was also found to be a risk factor associated with the endemic form of the autoimmune skin disease pemphigus foliaceus, which is described in the same regions where Chagas' disease is observed in Brazil. To obtain a further insight into the salivary biochemical and pharmacologic diversity of this kissing bug and to identify possible allergens that might be associated with this autoimmune disease, a cDNA library from its SGs was randomly sequenced. We present the analysis of a set of 2,230 (SG) cDNA sequences, 1,182 of which coded for proteins of a putative secretory nature.

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The aim of this study was to evaluate the erosive potential of orange juice modified with food-approved additives: 0.4 g/l of calcium (Ca) from calcium lactate pentahydrate, 0.2 g/l of linear sodium polyphosphate (LPP) or their combination (Ca+LPP) were added to a commercially available orange juice (negative control, C-). A commercially available calcium-modified orange juice (1.6 g/l of calcium) was the positive control (C+). These juices were tested using a short-term erosion in situ model, consisting of a five-phase, single-blind crossover clinical trial involving 10 subjects. In each phase, subjects inserted custom-made palatal appliances containing 8 bovine enamel specimens in the mouth and performed erosive challenges for a total of 0 (control), 10, 20, and 30 min. Two specimens were randomly removed from the appliances after each challenge period. Enamel surface microhardness was measured before and after the clinical phase and the percentage of surface microhardness change (%SMC) was determined. Before the procedures, in each phase, the subjects performed a taste test, where the juice assigned to that phase was blindly compared to C-. Overall, C+ showed the lowest %SMC, being the least erosive solution (p < 0.05), followed by Ca+LPP and Ca, which did not differ from each other (p > 0.05). LPP and C- were the most erosive solutions (p <0.05). Taste differences were higher for C+ (5/10 subjects) and Ca (4/10 subjects), but detectable in all groups, including C- (2/10 subjects). Calcium reduced the erosive potential of the orange juice, while no protection was observed for LPP. Copyright (C) 2012 S. Karger AG, Basel

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The expression of phospholipase C-β1 (PLC-β1) and cyclin D3 is highly induced during skeletal myoblast differentiation. We have previously shown that PLC-β1 activates cyclin D3 promoter during the differentiation of myoblasts to myotubes, indicating that PLC-β1 is a crucial regulator of mouse cyclin D3 gene. Here we report that PLC-β1 catalytic activity plays a role in the increase of cyclin D3 levels and in the induction of differentiation of C2C12 skeletal muscle cells. PLC-β1 mutational analysis revealed the importance of His331 and His378 for the catalytic activity. We show that following insulin administration, cyclin D3 mRNA levels are lower in cells overexpressing the PLC-β1 catalytically inactive form, as compared to wild type cells. We describe a novel signaling pathway elicited by PLC-β1 that modulates Activator Protein-1 (AP-1) activity. Indeed, gel mobility shift assays indicate that there is a c-jun binding site located in cyclin D3 promoter region specifically regulated by PLC-β1 and that c-jun binding activity is significantly increased by insulin stimulation and PLC-β1 overexpression. Moreover, mutation of c-jun/AP-1 binding site decreases the basal cyclin D3 promoter activity and eliminates its induction by insulin and PLC-β1 overexpression. Interestingly, we observed that the ectopic expression of the Inositol Polyphosphate Multikinase (IPMK) in C2C12 myoblasts enhances cyclin D3 gene expression and that the mutation of c-jun site in cyclin D3 promoter determines an impairment of IPMK-dependent promoter induction. These results indicate that PLC-β1 activates a c-jun/AP-1 target gene, i.e. cyclin D3, during myogenic differentiation through IPMK signaling.

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The EBPR (Enhanced Biological Phosphorus Removal) is a type of secondary treatment in WWTPs (WasteWater Treatment Plants), quite largely used in full-scale plants worldwide. The phosphorus occurring in aquatic systems in high amounts can cause eutrophication and consequently the death of fauna and flora. A specific biomass is used in order to remove the phosphorus, the so-called PAOs (Polyphosphate Accumulating Organisms) that accumulate the phosphorus in form of polyphosphate in their cells. Some of these organisms, the so-called DPAO (Denitrifying Polyphosphate Accumulating Organisms) use as electron acceptor the nitrate or nitrite, contributing in this way also to the removal of these compounds from the wastewater, but there could be side reactions leading to the formation of nitrous oxides. The aim of this project was to simulate in laboratory scale a EBPR, acclimatizing and enriching the specialized biomass. Two bioreactors were operated as Sequencing Batch Reactors, one enriched in Accumulibacter, the other in Tetrasphaera (both PAOs): Tetrasphaera microorganisms are able to uptake aminoacids as carbon source, Accumulibacter uptake organic carbon (volatile fatty acids, VFA). In order to measure the removal of COD, phosphorus and nitrogen-derivate compounds, different analysis were performed: spectrophotometric measure of phosphorus, nitrate, nitrite and ammonia concentrations, TOC (Total Organic Carbon, measuring the carbon consumption), VFA via HPLC (High Performance Liquid Chromatography), total and volatile suspended solids following standard methods APHA, qualitative microorganism population via FISH (Fluorescence In Situ Hybridization). Batch test were also performed to monitor the NOx production. Both specialized populations accumulated as a result of SBR operations; however, Accumulibacter were found to uptake phosphates at higher extents. Both populations were able to remove efficiently nitrates and organic compounds occurring in the feeding. The experimental work was carried out at FCT of Universidade Nova de Lisboa (FCT-UNL) from February to July 2014.

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Dent disease is a rare X-linked tubulopathy characterized by low molecular weight proteinuria, hypercalciuria, nephrocalcinosis and/or nephrolithiasis, progressive renal failure, and variable manifestations of other proximal tubule dysfunctions. It often progresses over a few decades to chronic renal insufficiency, and therefore molecular characterization is important to allow appropriate genetic counseling. Two genetic subtypes have been described to date: Dent disease 1 is caused by mutations of the CLCN5 gene, coding for the chloride/proton exchanger ClC-5; and Dent disease 2 by mutations of the OCRL gene, coding for the inositol polyphosphate 5-phosphatase OCRL-1. Herein, we review previously reported mutations (n = 192) and their associated phenotype in 377 male patients with Dent disease 1 and describe phenotype and novel (n = 42) and recurrent mutations (n = 24) in a large cohort of 117 Dent disease 1 patients belonging to 90 families. The novel missense and in-frame mutations described were mapped onto a three-dimensional homology model of the ClC-5 protein. This analysis suggests that these mutations affect the dimerization process, helix stability, or transport. The phenotype of our cohort patients supports and extends the phenotype that has been reported in smaller studies.

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Lowe syndrome is an X-linked disorder that has a complex phenotype that includes progressive renal failure and blindness. The disease is caused by mutations in an inositol polyphosphate 5-phosphatase designated OCRL. It has been shown that the OCRL protein is found on the surface of lysosomes and that a renal tubular cell line deficient in OCRL accumulated substrate phosphatidylinositol 4,5-bisphosphate. Because this lipid is required for vesicle trafficking from lysosomes, we postulate that there is a defect in lysosomal enzyme trafficking in patients with Lowe syndrome that leads to increased extracellular lysosomal enzymes and might lead to tissue damage and contribute to the pathogenesis of the disease. We have measured seven lysosomal enzymes in the plasma of 15 patients with Lowe syndrome and 15 age-matched male controls. We find a 1.6- to 2.0-fold increase in all of the enzymes measured. When the data was analyzed by quintiles of activity for all of the enzymes, we found that 95% of values in the lowest quintile come from normal subjects whereas in the highest quintile 85% of the values are from patients with Lowe syndrome. The increased enzyme levels are not attributable to renal insufficiency because there was no difference in enzyme activity in the four patients with the highest creatinine levels compared with the six patients with the lowest creatinine values.

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Several proteins secreted by enteric bacteria are thought to contribute to virulence by disturbing the signal transduction of infected cells. Here, we report that SopB, a protein secreted by Salmonella dublin, has sequence homology to mammalian inositol polyphosphate 4-phosphatases and that recombinant SopB has inositol phosphate phosphatase activity in vitro. SopB hydrolyzes phosphatidylinositol 3,4,5-trisphosphate, an inhibitor of Ca2+-dependent chloride secretion. In addition, SopB hydrolyzes inositol 1,3,4,5,6 pentakisphosphate to yield inositol 1,4,5,6-tetrakisphosphate, a signaling molecule that increases chloride secretion indirectly by antagonizing the inhibition of chloride secretion by phosphatidylinositol 3,4,5-trisphosphate [Eckmann, L., Rudolf, M. T., Ptasznik, A., Schultz, C., Jiang, T., Wolfson, N., Tsien, R., Fierer, J., Shears, S. B., Kagnoff, M. F., et al. (1997) Proc. Natl. Acad. Sci. USA 94, 14456–14460]. Mutation of a conserved cysteine that abolishes phosphatase activity of SopB results in a mutant strain, S. dublin SB c/s, with decreased ability to induce fluid secretion in infected calf intestine loops. Moreover, HeLa cells infected with S. dublin SB c/s do not accumulate high levels of inositol 1,4,5,6-tetrakisphosphate that are characteristic of wild-type S. dublin-infected cells. Therefore, SopB mediates virulence by interdicting inositol phosphate signaling pathways.

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HIV-1 replication is inhibited by the incorporation of chain-terminating nucleotides at the 3′ end of the growing DNA chain. Here we show a nucleotide-dependent reaction catalyzed by HIV-1 reverse transcriptase that can efficiently remove the chain-terminating residue, yielding an extendible primer terminus. Radioactively labeled 3′-terminal residue from the primer can be transferred into a product that is resistant to calf intestinal alkaline phosphatase and sensitive to cleavage by snake venom phosphodiesterase. The products formed from different nucleotide substrates have unique electrophoretic migrations and have been identified as dinucleoside tri- or tetraphosphates. The reaction is inhibited by dNTPs that are complementary to the next position on the template (Ki ≈ 5 μM), suggesting competition between dinucleoside polyphosphate synthesis and DNA polymerization. Dinucleoside polyphosphate synthesis was inhibited by an HIV-1 specific non-nucleoside inhibitor and was absent in mutant HIV-1 reverse transcriptase deficient in polymerase activity, indicating that this activity requires a functional polymerase active site. We suggest that dinucleoside polyphosphate synthesis occurs by transfer of the 3′ nucleotide from the primer to the pyrophosphate moiety in the nucleoside di- or triphosphate substrate through a mechanism analogous to pyrophosphorolysis. Unlike pyrophosphorolysis, however, the reaction is nucleotide-dependent, is resistant to pyrophosphatase, and produces dinucleoside polyphosphates. Because it occurs at physiological concentrations of ribonucleoside triphosphates, this reaction may determine the in vivo activity of many nucleoside antiretroviral drugs.