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1.
Botta M Distrutti E Mencarelli A Parlato MC Raffi F Cipriani S Fiorucci S 《ChemMedChem》2008,3(10):1580-1588
Nitric oxide (NO) is a gaseous mediator that exerts key regulatory functions in mammalian cells. Low levels of NO exert homeostatic functions and counteract inflammation, whereas high amounts of NO cause tissue destruction and cellular death. Herein we describe a new class of nitric oxide synthase (NOS) inhibitor NO-donating drugs (NI-NODs). Human endothelial cells and human monocyte-based activity screening showed that NI-NODs inhibit IL-1beta production, modulate PGE(2) production, and protect against apoptosis. In a rodent model of colitis, NI-NOD1 and NI-NOD2 potently decreased inflammation. These data show that NI-NODs are effective in both in vitro and in vivo models of inflammation, mimicking the positive effects of low levels of NO and suppressing NOS-induced NO production. 相似文献
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This work was aimed at producing potential nutraceutical peptides from flaxseed protein hydrolysate that can bind to calmodulin
(CaM) and inhibit the activity of CaM-dependent neuronal nitric oxide synthase (nNOS), an enzyme that has been implicated
in some forms of human diseases. Flaxseed protein isolate was hydrolyzed with alcalase, and the resultant protein hydrolysate
was passed through a 1000-Da M.W. cut-off membrane to isolate low-M.W. peptides. The permeate from the membrane was loaded
onto a cation-exchange column, and adsorbed peptides were separated into fractions I and II that had a content of 42 and 51%
basic amino acids, respectively. Kinetic analyses showed that both fractions were capable of binding to CaM, which led to
reductions in the activity of nNOS; the inhibition constant (K
j
) was 5.97 and 2.55 mg/mL for fractions I and II, respectively. Double reciprocal plots showed that the mode of enzyme inhibition
was mostly noncompetitive. Estimation of nNOS structure by fluorescence spectroscopy indicated that binding of the peptides
to CaM led to a gradual unfolding of enzyme structure as levels of the fractions were increased. We concluded that the flaxseed
protein-derived peptides may be used as ingredients for the formulation of therapeutic foods. 相似文献
4.
Background
Although nitric oxide is overproduced by macrophages and neutrophils after exposure to silica, its role in silica-induced inflammatory reaction and apoptosis needs further clarification. In this study, rats were intratracheally instilled with either silica suspension or saline to examine inflammatory reactions and intraperitoneally injected with ω-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthases, or saline to examine the possible role of nitric oxide production in the reaction. 相似文献5.
6.
Reaction of nitric oxide and nitric oxide + carbon monoxide with amorphous Fe-Co-B alloy powders 总被引:1,自引:0,他引:1
D. Mehandjiev D. Panayotov G. Tiuliev I. Mitov I. Dragieva 《Applied catalysis. B, Environmental》1995,5(3):199-219
The activity of amorphous Fe---Co---B alloy powder was investigated for the decomposition and the reduction of nitrogen monoxide. The transient response technique and a fixed bed reactor were applied to study the interactions of the Fe---Co---B alloy with two gas mixtures: NO + Ar at 353 and 573 K and NO + CO + Ar at 333–573 K. Moessbauer spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to study the state of the initial sample and the samples utilized in both gas mixtures. It is shown that the amorphous Fe---Co---B alloy powder has an activity for the direct decomposition of nitric oxide to nitrous oxide and nitrogen at a high gas space velocity (26 000 h−1). Oxygen from the decomposed nitric oxide poisons the surface for the formation of nitrogen. In the presence of carbon monoxide (a NO + CO + Ar gas mixture) nitric oxide is reduced to nitrous oxide at 333–353 K and fully reduced to nitrogen at 373–573 K. The quantities of the carbon dioxide formed are not equal to the values expected from the stoichiometry of the NO + CO reaction. Probably, the interaction of carbon monoxide with the adsorbed oxygen (left on the surface by the decomposed nitric oxide) enhances the rate of nitric oxide decomposition to nitrous oxide and nitrogen. The rate limiting steps for both reactions of nitric oxide decomposition, as indicated by the transient response data, change with increasing temperature. The data from the Moessbauer spectroscopy and the X-ray photoelectron spectroscopy (XPS) studies have shown that the amorphous Fe---Co---B alloy powder undergoes phase changes under the conditions of both, the NO + Ar and the NO + CO + Ar gas mixtures. Boron migrates to the surface of globules and serves the accumulation of oxygen by the formation of B2O3 (or B(OH)3). 相似文献
7.
Werner Weisweiler Klaus Eidam Michael Thiemann Erich Scheibler Karl Wilhelm Wiegand 《化学工程与技术》1991,14(4):270-274
This paper presents laboratory-scale measurements on the absorption of nitric oxide in dilute nitric acid. The NO concentration in the gas feed varied from 250 to 10 000 ppm. Nitrogen was used as carrier gas. The concentration of nitric acid was between 30 and 60 mass-%. Temperature during the measurements was set at 25 °C. In order to determine mass flow rates, experiments were performed in a double-stirred cell. This type of absorber has a defined gas/liquid interface as the mass transfer area. The liquid phase is introduced periodically and the gas phase continuously. A well-known model was used to describe the phenomenon of NO absorption. Several balance equations were established and solved. The calculated mass transfer rates were compared with those obtained experimentally. The empirical and theoretical data are in satisfactory agreement. 相似文献
8.
The activities for NO reduction with ammonia in the presence and absence of O2 have been examined over copper salts supported on activated carbon (AC) and carbon black (CB) which have been characterized by application of X-ray diffraction and scanning electron microscopy before and after use in the reduction process. The beneficial effects of increases in loading and the introduction of oxygen are demonstrated. On the most active catalyst and under optimum conditions 100% reduction of the NO to N2 occurs at 180 °C and Cu, Cu2O and CuO on the catalyst are shown to be present at various stages of the preparation and reduction process with large crystallites of metallic copper detected on the AC catalyst of optimum loading. Deactivation and regeneration of the catalysts is also examined. A mechanism for the redox process is proposed. This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Gabriele Centi Siglinda Perathoner Laura Dall''Olio 《Applied catalysis. B, Environmental》1994,4(4):L275-L281
The activity of ZSM-5 and boralite zeolites (Na, H and Cu forms) in the reduction of nitric oxide with propane / oxygen is compared. Copper ion-exchanged boralite is more active than a corresponding Cu-ZSM-5 sample with the same MFI structure, Si/M (M = Al or B) ratio and copper content, showing that in copper-exchanged samples Brønsted acid sites do not play a key role in the reaction mechanism, in contrast to that found for samples without the exchanged transition metal. 相似文献
10.
The catalytic activity of coke activated with sulphuric acid for the reduction of nitric oxide with ammonia at 150 °C was investigated. With the original coke the yield of nitrogen after 90 min reaction was only 10% and activation of the coke by the impregnation in sulphuric acid and subsequent heat treatment at ≈450 °C markedly enhanced the activity to a nitrogen yield as much as 70%. The activity decreased in repeated runs probably because of a surface coverage effect of the water produced, but the activity could be restored by further heat treatment at 400 °C. 相似文献
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The reduction of nitric oxide (NO) to nitrous oxide (N2O) by dithiothreitol in the presence of cobalt-centered corrin and porphyrin are presented. Reactions were monitored directly using Fourier transform infrared (FTIR) spectroscopy of vapor phase spectra. Reaction rates were two-fold faster for cobalt corrin than cobalt-centered porphyrins. The stoichiometry showed loss of two NO molecules per N2O generation. 相似文献
13.
Microbial reduction of sulfur dioxide and nitric oxide 总被引:1,自引:0,他引:1
Badri N. Dasu Vinay Deshmane Ramesh Shanmugasundram Cheng-Ming Lee Kerry L. Sublette 《Fuel》1993,72(12):1705-1714
Two process concepts have been developed for a microbial contribution to the problem of flue gas desulfurization and NOx removal. We have demonstrated that the sulfate-reducing bacterium Desulfovibrio desulfuricans can be grown in a mixed culture with fermentative heterotrophs in a medium in which glucose served as the only carbon source. Beneficial cross-feeding resulted in vigorous growth of D. desulfuricans, which used SO2(g) as a terminal electron acceptor, with complete reduction of SO2 to H2S in 1–2 s of contact time. We have proposed that the concentrated SO2 stream, obtained from regeneration of the sorbent in regenerable processes for flue gas desulfurization, could be split with two-thirds of the SO2 reduced to H2S by contact with a culture of sulfate-reducing bacteria. The resulting H2S could then be combined with the remaining SO2 and used as feed to a Claus reactor to produce elemental sulfur. However, the use of glucose as an electron donor in microbial SO2 reducing cultures would be prohibitively expensive. Therefore, if microbial reduction of SO2 is to be economically viable, less expensive electron donors must be found. Consequently, we have evaluated the use of municipal sewage sludge and elemental hydrogen as carbon and/or energy sources for SO2 reducing cultures. Heat and alkali pretreated sewage sludge has been successfully used as a carbon and energy source to support SO2 reduction in a continuous, anaerobic mixed culture containing D. desulfuricans. The culture operated for nine months with complete reduction of SO2 and H2S. Another sulfate-reducing bacterium, Desulfotomaculum orientis, has also been grown in batch cultures on a feed of SO2, H2 and CO2. Complete reduction of SO2 to H2S was observed with gas-liquid contact times of 1–2 s. We have also demonstrated that the facultative anaerobe and chemoautotroph, Thiobacillus denitrificans, can be cultured anoxically in batch reactors using NO(g) as a terminal electron acceptor with reduction to elemental nitrogen. We have proposed that the concentrated stream of NOx, as obtained from certain regenerable processes for flue gas desulfurization and NOx removal, could be converted to elemental nitrogen for disposal by contact with a culture T. denitrificans. Two heterotrophic bacteria have also been identified which may be grown in batch cultures with succinate or heat and alkali pretreated sewage sludge as carbon and energy sources and NO as a terminal electron acceptor. These are Paracoccus denitrificans and Pseudomonas denitrificans. 相似文献
14.
《Ceramics International》2017,43(6):4919-4925
Pure BT and BT doped with 1 and 2 mol% Zr, with orthorhombic-tetragonal (O-T) phase transitions near room temperature were prepared, with different grain sizes, by conventional ceramic method, at various sintering temperatures. Intrinsic and extrinsic effects of Zr addition on structural, dielectric, piezoelectric and ferroelectric properties of BT ceramics, near O-T phase transition were studied. In coarse grained ceramics, the intrinsic effects manifested in low field measurements (dielectric and piezoelectric constants), were reduced by Zr addition, while the extrinsic effects which control the high field response (remanent polarization and coercive field) were significantly enhanced. Instead, in fine grains ceramics, of either pure or doped BT, the extrinsic effects related to increased domain wall and grain boundaries density were dominant in both low and high field measurements, overlapping Zr effects. The results were explained in terms of crystal anisotropy correlated with grain size effects. 相似文献
15.
A.C.A. de Vooys 《Electrochimica acta》2004,49(8):1307-1314
A summary is given of recent work on the reactivity of nitric oxide on various metal electrodes. The significant differences between the reactivity of adsorbed NO and NO in solution are pointed out, both for the reduction and the oxidation reaction(s). Whereas adsorbed NO can be reduced only to hydroxylamine and/or ammonia, it takes NO in solution to produce N2O and N2. From the reduction of NO on a series on stepped single-crystal Pt electrodes, it is concluded that NOads reduction is not a structure sensitive process. The protonation of the adsorbed NO is rate-determining; neither the NO adsorption strength nor the NO bond breaking play a significant role in its reduction rate. Whereas adsorbed NO on polycrystalline Pt can only be oxidized to nitrate, in the presence of NO in solution nitrous acid HNO2 may also be formed, in a potential region where adsorbed NO is otherwise stable. Interestingly, on Pt(1 1 1) and Pt(5 5 4) NOads may be oxidized to HNO2 in a surface-bonded redox couple. Whereas surface oxides appear to catalyze the oxidation of solution NO to HNO2, the further oxidation to nitrate seems to be inhibited by the presence of surface oxides. Both the reduction and oxidation of solution NO appear to be not very metal-dependent reactions, as they take place with approximately equal rate on all electrode metals studied, including gold. This suggests the involvement of weakly adsorbed intermediates, and the relatively unimportant role of surface-bonded NO in the bulk NO reduction and oxidation activity. 相似文献
16.
Tsutomu Shikada Kaoru Fujimoto Taiseki Kunugi Hiro-O Tominaga 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1983,33(8):446-454
Highly active catalysts for the reduction of nitric oxide with ammonia can be obtained by supporting vanadium oxide, more than 15% by weight, on a silica gel with micropores of a mean diameter larger than 10 nm, followed by calcining it in the temperature range from 250 to 350°C. Both pre-impregnation with a small amount of titania and addition of ammonium bromide increased the activity markedly. The catalyst gave an NO conversion level of 100% at 150°C. A series of life tests of the catalysts, which was performed at 230°C using a simulated flue gas containing 700 parts/106 of sulphur dioxide, demonstrated that their activities were stable for more than 300 h. Little irreversible change in the catalyst properties was observed after the test. 相似文献
17.
Danilo Klvana Jitka Kirchnerová Carmen Tofan 《Korean Journal of Chemical Engineering》1999,16(4):470-477
Catalytic decomposition of nitric oxide has been studied for nearly a century, using materials ranging from noble metals to
alkaline earth metal oxides, without much success. Only since about last fifteen years some progress in finding promising
materials has been made. Of the numerous catalyst systems studied, very few show tangible decomposition rates : copper substituted
zeolites, silver-cobalt mixed oxides, some perovskites, and supported noble metals. Although at 773 K the rates of decomposition
over zeolites are two to three orders higher than those over remaining systems, these materials have very low thermal stability,
above 773 K. In this respect, perovskites have much higher potential, although so far no composition exhibiting practical
decomposition rates has been found. Systematic study of the effect of composition on the performance should help to advance
the complete understanding of this important reaction. In this paper a current state of art is outlined, and some latest preliminary
results for new specially formulated perovskites are presented. 相似文献
18.
McCleverty JA 《Chemical reviews》2004,104(2):403-418
19.
在管式炉石英固定床反应器上研究了程序升温条件下炭黑与NO反应的规律,主要研究了不同NO浓度、温度条件下不同炭黑、反应气中存在CO2、O2及其浓度改变时炭黑对NO的还原规律等.实验材料为在扩散火炬中取样得到的天然气炭黑、蜡烛炭黑、丁烷火焰炭黑,同时还选用了一种烟煤焦炭.实验结果表明:各炭黑试样与NO的反应有明确的起始反应温度和较好的反应规律;天然气炭黑比其他炭黑具有更高的脱除率、最低的起始反应温度;炭黑的起始反应温度随着NO反应气浓度增大而升高;反应气中氧存在可以降低炭黑-NO起始反应温度和反应程度最大点温度;反应气中CO2存在对天然气炭黑反应无影响,可以降低蜡烛炭黑和焦炭与NO起始反应温度,使反应分成两个阶段. 相似文献
20.
A series of chitosans with different molecular weights and degrees of acetylation (DAs) are reacted with nitric oxide (NO) to form [NONO]? groups. The effects of molecular weight and DA on NO release are investigated by Griess assay. Heterogeneous reaction of NH2 groups of chitosan with NO was shown to be influenced greatly by the crystalline form of chitosan. Total NO release exhibited a bell‐shaped distribution at different DAs ranging from 6 to 95%, peaking at about 50%. When DA is held constant, total NO release is directly proportional to the molecular weight. X‐ray diffraction patterns indicate that the total NO release of chitosan‐NO adducts is in general agreement with the intensity of reflections at low Bragg angles (2θ = 8.6°–11.1°), and in turn, a relaxed hydration crystalline form and NO molecules could penetrate this crystal and react with the chitosan molecules. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献