The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Peter C Dedon - One of the best experts on this subject based on the ideXlab platform.
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in situ analysis of 8 oxo 7 8 dihydro 2 deoxyguanosine oxidation reveals sequence and agent specific damage spectra
Journal of the American Chemical Society, 2012Co-Authors: Kok Seong Lim, Liang Cui, Koli Taghizadeh, John S Wishnok, Wan Chan, Michael S Demott, Ramesh I Babu, Steven R Tannenbaum, Peter C DedonAbstract:Guanine is a major target for oxidation in DNA, with 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) as a major product. 8-oxodG is itself significantly more susceptible to oxidation than guanine, with the resulting damage consisting of more than 10 different products. This complexity has hampered efforts to understand the determinants of biologically relevant DNA oxidation chemistry. To address this problem, we have developed a high mass accuracy mass spectrometric method to quantify oxidation products arising site specifically in DNA. We applied this method to quantify the role of sequence context in defining the spectrum of damage products arising from oxidation of 8-oxodG by two oxidants: nitrosoperoxycarbonate (ONOOCO2–), a macrophage-derived Chemical Mediator of inflammation, and the classical one-electron oxidant, riboflavin-mediated photooxidation. The results reveal the predominance of dehydroguanidinohydantoin (DGh) in 8-oxodG oxidation by both oxidants. While the relative quantities of 8-oxodG ox...
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sequence dependent variation in the reactivity of 8 oxo 7 8 dihydro 2 deoxyguanosine toward oxidation
Chemical Research in Toxicology, 2012Co-Authors: Kok Seong Lim, Vladimir Shafirovich, Nicholas E Geacintov, Koli Taghizadeh, John S Wishnok, Ramesh I Babu, Peter C DedonAbstract:The goal of this study was to define the effect of DNA sequence on the reactivity of 8-oxo-7,8dihydro-2'-deoxyguanosine (8-oxodG) toward oxidation. To this end, we developed a quadrupole/ time-of-flight (QTOF) mass spectrometric method to quantify the reactivity of site-specifically modified oligodeoxyribonucleotides with two model oxidants: nitrosoperoxycarbonate (ONOOCO − 2), a Chemical Mediator of inflammation, and photoactivated riboflavin, a classical one-electron oxidant widely studied in mutagenesis and charge transport in DNA. In contrast to previous observations with guanine (Margolin, Y., et al., Nat. Chem. Biol. 2, 365, 2006), sequence context did not affect the reactivity of ONOOCO2 − with 8-oxodG, but photosensitized riboflavin showed a strong sequence preference in its reactivity with the following order (8-oxodG = O): COA ≈ AOG > GOG ≥ COT > TOC > AOC. That the COA context was the most reactive was unexpected and suggests a new sequence context where mutation hotspots might occur. These results point to both sequence- and agent-specific effects on 8-oxodG oxidation.
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erratum paradoxical hotspots for guanine oxidation by a Chemical Mediator of inflammation nature Chemical biology 2006 2 365 366
Nature Chemical Biology, 2007Co-Authors: Yelena Margolin, Jeanfrancois Cloutier, Vladimir Shafirovich, Nicholas E Geacintov, Peter C DedonAbstract:Nature Chemical Biology 2, 365–366 (2006); published online 4 June 2006; corrected after print 23 January 2007 In the version of this article initially published, the y axis of the graph in Figure 2 was incorrectly labeled. The axis should read “Ratio of Fpg- to piperidine-sensitive products,” not “Ratio of piperidine- to Fpg-sensitive products.
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paradoxical hotspots for guanine oxidation by a Chemical Mediator of inflammation
Nature Chemical Biology, 2006Co-Authors: Yelena Margolin, Jeanfrancois Cloutier, Vladimir Shafirovich, Nicholas E Geacintov, Peter C DedonAbstract:Guanine in DNA is a major oxidation target owing to its low ionization potential (IP), and there is often an inverse correlation between damage frequency and sequence-dependent variation in guanine IP. We report that the biological oxidant nitrosoperoxycarbonate (ONOOCO2(-)) paradoxically selects guanines with the highest IP in GC-containing contexts. Along with sequence-dependent variation in damage chemistry, this behavior points to factors other than charge migration as determinants of genomic DNA oxidation.
Fabrizio Briganti - One of the best experts on this subject based on the ideXlab platform.
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fungal laccase cellobiose dehydrogenase and Chemical Mediators combined actions for the decolorization of different classes of textile dyes
Bioresource Technology, 2008Co-Authors: Ilaria Ciullini, Silvia Tilli, Andrea Scozzafava, Fabrizio BrigantiAbstract:Dyes belonging to the mono-, di-, tri- and poly-azo as well as anthraquinonic and mono-azo Cr-complexed classes, chosen among the most utilized in textile applications, were employed for a comparative enzymatic decolorization study using the extracellular crude culture extracts from the white rot fungus Funalia (Trametes) trogii grown on different culture media and activators able to trigger different levels of expression of oxidizing enzymes: laccase and cellobiose dehydrogenase. Laccase containing extracts were capable to decolorize some dyes from all the different classes analyzed, whereas the recalcitrant dyes were subjected to the combined action of laccase and the Chemical Mediator HBT, or laccase plus cellobiose dehydrogenase. Correlations among the decolorization degree of the various dyes and their electronic and structural diversities were rationalized and discussed. The utilization of cellobiose dehydrogenase in support to the activity of laccase for the decolorization of azo textile dyes resulted in substantial increases in decolorization for all the refractory dyes proving to be a valid alternative to more expensive and less environmentally friendly Chemical treatments of textile dyes wastes.
Hiroko Isoda - One of the best experts on this subject based on the ideXlab platform.
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isolation of 5 hydroxymethyl furfural from lycium chinense and its inhibitory effect on the Chemical Mediator release by basophilic cells
Planta Medica, 2011Co-Authors: Parida Yamada, Mai Nemoto, Hideyuki Shigemori, Shinichi Yokota, Hiroko IsodaAbstract:The effect of hot water extracts of LYCIUM CHINENSE fruits (LCF) on the β-hexosaminidase ( β-hexo) release by IgE sensitized BSA stimulated rat basophilic leukemia (RBL-2H3) cells was investigated. The ethylacetate (EtOAc) layer of the extract has shown an inhibitory effect on β-hexo release from RBL-2H3 cells at the antigen antibody binding stage. The water (H 2 O) fraction (EFW) of the chloroform (CHCl 3 ) extract from the EtOAc layer also inhibited β-hexo release at the same stage in a dose-dependent manner. With column chromatography preparation, proton and carbon nuclear magnetic resonance ( 1 H and 13 C NMR) spectra, electron ionization mass spectrometer (EI-MS) spectra, and high-performance liquid chromatography (HPLC) analysis, the active component was determined to be 5-(hydroxymethyl)furfural (5-HMF). Thus, the 5-HMF showed an inhibitory effect on β-hexo release at the antigen-antibody binding stage and the antibody-receptor binding stage. Furthermore, 5-HMF suppressed [Ca 2+ ] I influx in the IgE-sensitized BSA-stimulated RBL-2H3 cells. Our results show that 5-HMF may be useful for the treatment or prevention of type I allergic diseases.
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inhibitory effect of acteoside isolated from cistanche tubulosa on Chemical Mediator release and inflammatory cytokine production by rbl 2h3 and ku812 cells
Planta Medica, 2010Co-Authors: Parida Yamada, Jun Kyu Han, Hideyuki Shigemori, Shinichi Yokota, Rieko Iijima, Hiroko IsodaAbstract:The immediate-type allergic reaction is involved in many allergic diseases such as asthma, allergic rhinitis, and sinusitis. In this study, we investigated the effect of acteoside extracted from CISTANCHE TUBULOSA (Schrenk) R. Wight on the basophilic cell-mediated allergic reaction. The effect of acteoside on β-hexosaminidase release and intracellular [Ca 2+ ] I level from rat basophilic leukemia (RBL-2H3) cells was determined. Also, ELISA was used to determine the level of histamine, tumor necrosis factor (TNF)- α, and interleukin (IL)-4 on human basophilic (KU812) cells. The effect of acteoside on basophilic cell viability was determined using the 3-[4,5-dimethylthiazolyl]-2,5-diphenyltetrazolium bromide (MTT) assay. These results indicated that 0.1-10.0 μg/mL acteoside inhibits the release of β-hexosaminidase and [Ca 2+ ] I influx from IgE-mediated RBL-2H3 cells. Moreover, acteoside inhibited histamine release, TNF- α, and IL-4 production in a dose-dependent manner from calcium ionophore A23187 plus phorbol 12-myristate 13-acetate (PMA) or compound 48/80-stimulated KU812 cells. Our findings provide evidence that acteoside inhibits basophilic cell-derived immediate-type and delayed-type allergic reactions. This is the first report describing antiallergic activity of acteoside extracted from CISTANCHE TUBULOSA on basophilic cells.
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inhibitory effect of fulvic acid extracted from canadian sphagnum peat on Chemical Mediator release by rbl 2h3 and ku812 cells
Bioscience Biotechnology and Biochemistry, 2008Co-Authors: Parida Yamada, Hiroko Isoda, Jun Kyu Han, Terence P N Talorete, Tatsuaki Yamaguchi, Yukuo AbeAbstract:Fulvic acid (FA) was extracted and purified from Canadian Sphagnum peat (CP-FA) and characterized by using an element analysis meter, Fourier transform infrared (FT-IR) spectroscopy, electron spin resonance (ESR) spectroscopy, and 13C-nuclear magnetic resonance (13C-NMR) spectroscopy. To investigate the antiallergic effect of CP-FA, we incubated rat basophilic leukemia (RBL-2H3) cells with 0.001–10.0 μg/ml of CP-FA and determined the β-hexosaminidase release inhibition at different response stages. The intracellular calcium [Ca2+] i level was also determined by using Fluo 3-AM, a calcium-specific fluorescent probe, and the cytotoxicity of CP-FA was determined by the 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. The results revealed that RBL-2H3 cells incubated for 48 h with 0.001–10.0 μg/ml of CP-FA did not show any decreased viability. CP-FA inhibited the β-hexosaminidase release by IgE-sensitized, antigen-stimulated RBL-2H3 cells at the antigen-antibody binding stage and the ...
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inhibitory effect of various tunisian olive oils on Chemical Mediator release and cytokine production by basophilic cells
Journal of Ethnopharmacology, 2008Co-Authors: Parida Yamada, Mokhtar Zarrouk, K Kawasaki, Hiroko IsodaAbstract:Abstract Tunisian olive oils have been traditionally used as a medicinal food for chronic inflammation. To investigate the antiallergic effect of virgin olive oil samples from five principal olive varieties grown in various regions of Tunisia, we used the type I allergy reaction model using rat basophilic leukemia (RBL-2H3) cells and different dilutions of olive oil samples to determine β-hexosaminidase release inhibition at two different response stages. Results showed that the Sayali olive oil significantly inhibited β-hexosaminidase release by the IgE antibody-sensitized, BSA antigen-stimulated RBL-2H3 cells at the antibody-antigen binding stage. The result of our experiment shows that the anti-allergic effect of olive oil at this binding stage may be dependent on their flavone content. The Zarrazi olive oil significantly inhibited β-hexosaminidase release at the antigen-receptor binding stage. Moreover, we investigated the effect of olive oil samples on histamine release and production of cytokines by activated human basophilic (KU812) cells. Different dilutions of Sayali olive oil dose-dependently inhibited the production of tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4), and different dilutions of Zarrazi olive oil dose-dependently inhibited histamine release and IL-4 production by calcium ionophore A23187 plus phorbol 12-myristate 13-acetate (PMA)-stimulated KU812 cells.
Ilaria Ciullini - One of the best experts on this subject based on the ideXlab platform.
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fungal laccase cellobiose dehydrogenase and Chemical Mediators combined actions for the decolorization of different classes of textile dyes
Bioresource Technology, 2008Co-Authors: Ilaria Ciullini, Silvia Tilli, Andrea Scozzafava, Fabrizio BrigantiAbstract:Dyes belonging to the mono-, di-, tri- and poly-azo as well as anthraquinonic and mono-azo Cr-complexed classes, chosen among the most utilized in textile applications, were employed for a comparative enzymatic decolorization study using the extracellular crude culture extracts from the white rot fungus Funalia (Trametes) trogii grown on different culture media and activators able to trigger different levels of expression of oxidizing enzymes: laccase and cellobiose dehydrogenase. Laccase containing extracts were capable to decolorize some dyes from all the different classes analyzed, whereas the recalcitrant dyes were subjected to the combined action of laccase and the Chemical Mediator HBT, or laccase plus cellobiose dehydrogenase. Correlations among the decolorization degree of the various dyes and their electronic and structural diversities were rationalized and discussed. The utilization of cellobiose dehydrogenase in support to the activity of laccase for the decolorization of azo textile dyes resulted in substantial increases in decolorization for all the refractory dyes proving to be a valid alternative to more expensive and less environmentally friendly Chemical treatments of textile dyes wastes.
H Nagai - One of the best experts on this subject based on the ideXlab platform.
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role of cyclic 3 5 adenosine monophosphate in the regulation of Chemical Mediator release and cytokine production from cultured human mast cells
The Journal of Allergy and Clinical Immunology, 1999Co-Authors: M Shichijo, N Inagaki, M Kimata, I Serizawa, H Saito, H NagaiAbstract:Abstract Background: Cultured human mast cells are known to resemble human lung mast cells in terms of the profiles of intracellular protease, the characteristics of histamine release, and the pharmacologic properties. Objective: The role of cyclic 3 ,5 -adenosine monophosphate (cAMP) in Chemical Mediator release and cytokine production by human mast cells was determined. Methods: We investigated the effects of cAMP-elevating agents on IgE-mediated Chemical Mediator release and cytokine production by cultured human mast cells. We also examined the relationship between intracellular cAMP levels and the inhibition of Chemical Mediator release or cytokine production by various drugs. Results: β-agonists significantly suppressed IgE-mediated release of histamine, leukotrienes, and PGD 2 (Chemical Mediators) and the production of GM-CSF, IL-5 and macrophage inflammatory protein-1α (cytokines). Phosphodiesterase inhibitors (theophylline, rolipram, and cilostazol) had no effect on Chemical Mediators but suppressed cytokine production. Dibutyryl cAMP significantly suppressed both Chemical Mediator release and cytokine production, suggesting that their induction was regulated by intracellular cAMP. Elevation of cAMP by β-agonists at 10 minutes after treatment correlated well with the inhibition of histamine release. There was a significant relationship between cAMP elevation at 180 minutes and the inhibition of GM-CSF production at 360 minutes by β-agonists, rolipram, or cilostazol. Although 100 μmol/L theophylline significantly inhibited GM-CSF production, it had no effect on cAMP. Conclusion: Elevation of cAMP may be responsible for the inhibitory effect of β-agonists, rolipram, and cilostazol on Chemical Mediator release and cytokine production by cultured human mast cells. In contrast, theophylline may inhibit GM-CSF production independently of cAMP. (J Allergy Clin Immunol 1999;103:S421-8.)
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Role of cyclic 3',5'-adenosine monophosphate in the regulation of Chemical Mediator release and cytokine production from cultured human mast cells.
The Journal of allergy and clinical immunology, 1999Co-Authors: M Shichijo, N Inagaki, M Kimata, I Serizawa, H Saito, H NagaiAbstract:Cultured human mast cells are known to resemble human lung mast cells in terms of the profiles of intracellular protease, the characteristics of histamine release, and the pharmacologic properties. The role of cyclic 3',5'-adenosine monophosphate (cAMP) in Chemical Mediator release and cytokine production by human mast cells was determined. We investigated the effects of cAMP-elevating agents on IgE-mediated Chemical Mediator release and cytokine production by cultured human mast cells. We also examined the relationship between intracellular cAMP levels and the inhibition of Chemical Mediator release or cytokine production by various drugs. beta-agonists significantly suppressed IgE-mediated release of histamine, leukotrienes, and PGD2 (Chemical Mediators) and the production of GM-CSF, IL-5 and macrophage inflammatory protein-1alpha (cytokines). Phosphodiesterase inhibitors (theophylline, rolipram, and cilostazol) had no effect on Chemical Mediators but suppressed cytokine production. Dibutyryl cAMP significantly suppressed both Chemical Mediator release and cytokine production, suggesting that their induction was regulated by intracellular cAMP. Elevation of cAMP by beta-agonists at 10 minutes after treatment correlated well with the inhibition of histamine release. There was a significant relationship between cAMP elevation at 180 minutes and the inhibition of GM-CSF production at 360 minutes by beta-agonists, rolipram, or cilostazol. Although 100 micromol/L theophylline significantly inhibited GM-CSF production, it had no effect on cAMP. Elevation of cAMP may be responsible for the inhibitory effect of beta-agonists, rolipram, and cilostazol on Chemical Mediator release and cytokine production by cultured human mast cells. In contrast, theophylline may inhibit GM-CSF production independently of cAMP.
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Role of cyclic 3 ́,5 ́-adenosine monophosphate in the regulation of Chemical Mediator release and cytokine production from cultured human mast cells
Journal of Allergy and Clinical Immunology, 1999Co-Authors: M Shichijo, N Inagaki, M Kimata, I Serizawa, H Saito, H NagaiAbstract:Abstract Background: Cultured human mast cells are known to resemble human lung mast cells in terms of the profiles of intracellular protease, the characteristics of histamine release, and the pharmacologic properties. Objective: The role of cyclic 3 ,5 -adenosine monophosphate (cAMP) in Chemical Mediator release and cytokine production by human mast cells was determined. Methods: We investigated the effects of cAMP-elevating agents on IgE-mediated Chemical Mediator release and cytokine production by cultured human mast cells. We also examined the relationship between intracellular cAMP levels and the inhibition of Chemical Mediator release or cytokine production by various drugs. Results: β-agonists significantly suppressed IgE-mediated release of histamine, leukotrienes, and PGD 2 (Chemical Mediators) and the production of GM-CSF, IL-5 and macrophage inflammatory protein-1α (cytokines). Phosphodiesterase inhibitors (theophylline, rolipram, and cilostazol) had no effect on Chemical Mediators but suppressed cytokine production. Dibutyryl cAMP significantly suppressed both Chemical Mediator release and cytokine production, suggesting that their induction was regulated by intracellular cAMP. Elevation of cAMP by β-agonists at 10 minutes after treatment correlated well with the inhibition of histamine release. There was a significant relationship between cAMP elevation at 180 minutes and the inhibition of GM-CSF production at 360 minutes by β-agonists, rolipram, or cilostazol. Although 100 μmol/L theophylline significantly inhibited GM-CSF production, it had no effect on cAMP. Conclusion: Elevation of cAMP may be responsible for the inhibitory effect of β-agonists, rolipram, and cilostazol on Chemical Mediator release and cytokine production by cultured human mast cells. In contrast, theophylline may inhibit GM-CSF production independently of cAMP. (J Allergy Clin Immunol 1999;103:S421-8.)