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1.
Results of investigation of biochemical mechanisms of N-stearoylethanolamine (NSE) influence on the processes of allergic responses of immediate and delayed type (anaphylactic shock in guinea pigs and contact hypersensitivity to 2,4-dinitrochlorobenzene in mice) are presented in the paper. NSE was given per os during two weeks. It was found that in anaphylactic animals, NSE prevented the growth of histamine levels in the heart, kidneys and spleen, suppressed NO2(-) level increase in these organs and promoted its normalization. At the same time NSE prevented the decrease of the level of stable metabolite of nitrogen oxide - nitrite-anion (NO2(-)) in the liver and to a lesser degree in the lungs, and also decreased the activity both inducible and constitutive NO-synthases. NSE normalized the content of TBA-reactive products in the lungs and decreased it in the heart, diminished the decline of activity of glutathione peroxidase, catalase and superoxide dismutase. Effects of NSE depended on its daily dose. About 70% of animals which received NSE in a dose 65 mg/kg of body weight had no fatal outcome after the induction of anaphylactic shock. NSE suppressed the delayed type hypersensitivity response and normalized NO2(-) content in the blood plasma of mice but only at the dose of 50 mg/kg of weight. In the thymus of sensitized mice NSE diminished the content of NO2(-). Thus, though NSE has no affinity for specific CB receptors, in other words, it is not a typical endocannabinoid, its ability to influence the immediate and delayed type allergic reactions opens a perspective for creation of new medications which differ principally from existing pharmacological drugs with anti-allergic and immunosuppressive properties.  相似文献   

2.
The influence of N-stearoylethanolamine (NSE) on the NO-synthase way of NO generation and phospholipids composition of erythrocyte membranes of rats with streptozotocine-induced diabetes has been studied. It has been shown that the activation of iNOS activity, cNOS activity inhibition and increase of the stable NO metabolites content takes place in the red blood cells (RBC) of diabetic rats. The alterations were also found in the RBC membrane phospholipid content: a decrease of phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, sphingomieline content and increase of phosphatidylethanolamine, phosphatidylcholine lysoforms level. The NSE suspension administration (50 mg/kg of body weight) to diabetic rats (3 months after the diabetes induction) resulted in iNOS activity inhibition, recovering of cNOS activity and normalization of NO stable metabolites level in RBC. The decrease of phospholipids lysoform levels, normalization of phosphatidylethanolamine, phosphatidylcholine content and increase of phosphatidylinositol level were found after NSE action.  相似文献   

3.
The purpose of this research was to study the humoral link of autoimmune response to the brain antigen i.e. neurospecific enolase (NSE) in liquidators of the Chernobyl accident aftereffects diagnosed as having "postradiation encephalopathy" (PREP). Determined in the PREP patients' serum were: NSE content, level of autoantibodies to NSE, concentration and size of the immune complexes (IC) as well as NSE content in the IC. The majority of PREP patients revealed high serum level of NSE and high level of autoantibodies to NSE. Concentration of small and middle-size IC was 2-3 times higher than normal. So the presence of circulating NSE and autoantibodies thereto in the liquidators' blood serum evidences of an organic lesion of the brain neurons, this causing the development of neurological syndromes. It is likely that at certain stages of the PREP pathogenesis there appear autoimmune responses to neuroantigens which prove the destructive effects of radiation on the CNS. Probably, in patients with PREP 2-3 degrees the autoimmune processes become chronic due to pathogenic action of free autoantibodies to NSE and of small NSE-anti-NSE complexes which are known to be the most pathogenic and capable of being fixed on complementary brain structures promoting their damage.  相似文献   

4.
The inhibitory effects of nitrate (NO3-) and nitrite (NO2-) on dissimilatory iron (FE3+) reduction were examined in a series of electron acceptor competition experiments using Shewanella putrefaciens 200 as a model iron-reducing microorganism. S. putrefaciens 200 was found to express low-rate nitrate reductase, nitrite reductase, and ferrireductase activity after growth under highly aerobic conditions and greatly elevated rates of each reductase activity after growth under microaerobic conditions. The effects of NO3- and NO2- on the Fe3+ reduction activity of both aerobically and microaerobically grown cells appeared to follow a consistent pattern; in the presence of Fe3+ and either NO3- or NO2-, dissimilatory Fe3+ and nitrogen oxide reduction occurred simultaneously. Nitrogen oxide reduction was not affected by the presence of Fe3+, suggesting that S. putrefaciens 200 expressed a set of at least three physiologically distinct terminal reductases that served as electron donors to NO3-, NO2-, and Fe3+. However, Fe3+ reduction was partially inhibited by the presence of either NO3- or NO2-. An in situ ferrozine assay was used to distinguish the biological and chemical components of the observed inhibitory effects. Rate data indicated that neither NO3- nor NO2- acted as a chemical oxidant of bacterially produced Fe2+. In addition, the decrease in Fe3+ reduction activity observed in the presence of both NO3- and NO2- was identical to the decrease observed in the presence of NO2- alone. These results suggest that bacterially produced NO2- is responsible for inhibiting electron transport to Fe3+.  相似文献   

5.
Nitric oxide (NO) aqueous solutions were prepared by saturating pure NO gas and hydrolyzing 1 mM 1-hydroxy-2-oxo-3-(N-methyl-3-aminoethyl)-3-methyl-1-triazene (NOC-7), a NO donor, under anerobic conditions. The modified Saltzman method was employed for standardization of the NO aqueous solutions. NO and NO(2) in the solutions were driven with nitrogen gas stream into the first Saltzman solution to measure NO(2) and the leaked NO was driven with air stream through an oxidizing solution into the second Saltzman solution to measure NO, and NO(-)(2) and NO(-)(3) in the residual solutions were determined directly and after reduction with nitrate reductase, respectively. The concentrations of nitrogen oxide species in the NO solutions were about 1.8 mM NO/0.01 mM NO(2)/0.1 mM NO(-)(2)/0.1 mM NO(-)(3), and unchanged during keeping at 20 degrees C for 1 h under anerobic conditions but became 0.05 mM NO/0.01 mM NO(2)/1.7 mM NO(-)(2)/0.1 mM NO(-)(3) by keeping at 20 degrees C for 10 min under aerobic conditions. Instability of NO under aerobic conditions was supported by consumption of 1/4 equivalent amount of dissolved oxygen, and by loss of ability to convert 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO) to carboxy-PTI. Simultaneous quantification of nitrogen oxide species by the modified Saltzman method was found to be useful for practical standardization of NO aqueous solutions.  相似文献   

6.
Volume-regulated anion channels (VRACs) are critically important for cell volume homeostasis, and under pathological conditions contribute to neuronal damage via excitatory amino (EAA) release. The precise mechanisms by which brain VRACs are activated and/or modulated remain elusive. In the present work we explored the possible involvement of nitric oxide (NO) and NO-related reactive species in the regulation of VRAC activity and EAA release, using primary astrocyte cultures. The NO donors sodium nitroprusside and spermine NONOate did not affect volume-activated d-[3H]aspartate release. In contrast, the peroxynitrite (ONOO-) donor 3-morpholinosydnomine hydrochloride (SIN-1) increased volume-dependent EAA release by approx. 80-110% under identical conditions. Inhibition of ONOO- formation with superoxide dismutase completely abolished the effects of SIN-1. Both the volume- and SIN-1-induced EAA release were sensitive to the VRAC blockers NPPB and ATP. Further pharmacological analysis ruled out the involvement of cGMP-dependent reactions and modification of sulfhydryl groups in the SIN-1-inducedmodulation of EAA release. The src family tyrosine kinase inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo [3,4-d]pyrimidine (PP2), but not its inactive analog PP3, abolished the effects of SIN-1. A broader spectrum tyrosine kinase inhibitor tyrphostin A51, also completely eliminated the SIN-1-induced EAA release. Our data suggest that ONOO- up-regulates VRAC activity via a src tyrosine kinase-dependent mechanism. This modulation may contribute to EAA-mediated neuronal damage in ischemia and other pathological conditions favoring cell swelling and ONOO- production.  相似文献   

7.
Kinetics of biofilm nitrification   总被引:5,自引:0,他引:5  
The reaction rates (r(NH(4) (+) ) and r(NO(2) (-) )) in the two-step nitrification reaction were measured in a fluidized-sand-bed biofilm reactor under a range of steady-state conditions with respect to bulk NH(4) (+), NO(2) (-), and O(2) concentrations. It was shown from theory and experiment that under low NH(4) (+) concentration conditions, if the O(2)/NH(4) (+) concentration ratio in the bulk liquid is less than the stoichiometric coefficient (3.4 mg/mg), then oxygen will be rate limiting. In all experiments r(NO(2) (-) ) decreased more than r(NH(4) (+) ) under low oxygen conditions. This resulted in high NO(2) (-) effluent concentrations under low residence time conditions. The influence of the oxygen penetration effects on the relative values of r(NH(4) (+) ) and r(NO(2) (-) ) was experimentally shown to be caused either by the Nitrobacter location in the inner biofilm regions or by a K(m) effect for oxygen. Theoretical support of these findings was provided by a differential diffusion-reaction model which was used to simulate the experimental results.  相似文献   

8.
Root NO3- uptake and expression of two root NO3- transporter genes (Nrt2;1 and Nrt1) were investigated in response to changes in the N- or C-status of hydroponically grown Arabidopsis thaliana plants. Expression of Nrt2;1 is up-regulated by NO3 - starvation in wild-type plants and by N-limitation in a nitrate reductase (NR) deficient mutant transferred to NO3- as sole N source. These observations show that expression of Nrt2;1 is under feedback repression by N-metabolites resulting from NO3- reduction. Expression of Nrt1 is not subject to such a repression. However, Nrt1 is over-expressed in the NR mutant even under N-sufficient conditions (growth on NH4NO3 medium), suggesting that expression of this gene is affected by the presence of active NR, but not by N-status of the plant. Root 15NO3- influx is markedly increased in the NR mutant as compared to the wild-type. Nevertheless, both genotypes have similar net 15NO3- uptake rates due to a much larger 14NO3- efflux in the mutant than in the wild-type. Expressions of Nrt2;1 and Nrt1 are diurnally regulated in photosynthetically active A. thaliana plants. Both increase during the light period and decrease in the first hours of the dark period. Sucrose supply prevents the inhibition of Nrt2;1 and Nrt1 expressions in the dark. In all conditions investigated, Nrt2;1 expression is strongly correlated with root 15NO3- influx at 0.2 mM external concentration. In contrast, changes in the Nrt1 mRNA level are not always associated with similar changes in the activities of high- or low-affinity NO3- transport systems.  相似文献   

9.
A strategy for sequential hydrocarbon bioremediation is proposed. The initial O(2)-requiring transformation is effected by aerobic resting cells, thus avoiding a high oxygen demand. The oxygenated metabolites can then be degraded even under anaerobic conditions when supplemented with a highly water-soluble alternative electron acceptor, such as nitrate. To develop the new strategy, some phenomena were studied by examining Pseudomonas aeruginosa fermentation. The effects of dissolved oxygen (DO) concentration on n-hexadecane biodegradation were investigated first. Under microaerobic conditions, the denitrification rate decreased as the DO concentration decreased, implying that the O(2)-requiring reactions were rate limiting. The effects of different nitrate and nitrite concentrations were examined next. When cultivated aerobically in tryptic soy broth supplemented with 0 to 0.35 g of NO(2)(-)-N per liter, cells grew in all systems, but the lag phase was longer in the presence of higher nitrite concentrations. However, under anaerobic denitrifying conditions, even 0.1 g of NO(2)(-)-N per liter totally inhibited cell growth. Growth was also inhibited by high nitrate concentrations (>1 g of NO(3)(-)-N per liter). Cells were found to be more sensitive to nitrate or nitrite inhibition under denitrifying conditions than under aerobic conditions. Sequential hexadecane biodegradation by P. aeruginosa was then investigated. The initial fermentation was aerobic for cell growth and hydrocarbon oxidation to oxygenated metabolites, as confirmed by increasing dissolved total organic carbon (TOC) concentrations. The culture was then supplemented with nitrate and purged with nitrogen (N(2)). Nitrate was consumed rapidly initially. The live cell concentration, however, also decreased. The aqueous-phase TOC level decreased by about 40% during the initial active period but remained high after this period. Additional experiments confirmed that only about one-half of the derived TOC was readily consumable under anaerobic denitrifying conditions.  相似文献   

10.
* A previously published model of crop nitrogen (N) status based on intercepted photosynthetically active radiation (R(i), mol per plant) suggested that plant organic N accumulation is related to R(i) by a constant ratio, defined hereafter as the radiation use efficiency for N (NRUE). The aim of this paper was to compare the effects of N nutrition and CO2 enrichment on NRUE and RUE (radiation use efficiency for biomass accumulation). * In three unrelated glasshouse experiments, tomato plants (Solanum lycopersicum) grown in hydroponics were fed for 28 d (exponential growth) with full solutions containing constant NO3(-) concentrations ([NO3(-)]) ranging from 0.05 to 15 mol m(-3), both under ambient or CO2-enriched (1000 microl l(-1)) air. * Each experiment comprised five harvests. Low [NO3(-)] (< 0.3 mol m(-3)) limited growth via leaf area (LA) restriction and decreased light interception. CO2 enrichment enhanced dry weight and LA. RUE was not affected by [NO3(-)], but increased under CO2-enriched air. By contrast, NRUE was not affected by [NO3(-)] or CO2 enrichment. * It is suggested that the radiation efficiency for organic N acquisition (NRUE) did not depend on C or N nutrition for young plants grown under unstressed conditions.  相似文献   

11.
Denitrification of nitrate by the fungus Cylindrocarpon tonkinense   总被引:1,自引:0,他引:1  
The denitrifying fungus Cylindrocarpon tonkinense was thought to be able to denitrify only nitrite (NO2-) but not nitrate (NO3-) to form nitrous oxide (N2O). Here we found, however, that C. tonkinense can denitrify NO3- under certain conditions. Presence of ammonium (NH3+) in addition to NO3- and the use of a fermentable sugar as an electron donor were key conditions for inducing the denitrifying activity. Such induction accompanied a remarkable increase in the intracellular level of the enzyme activities related to NO3- metabolism. These activities contained assimilatory type NADPH (or NADH)-dependent NO3- reductase (aNar), dissimilatory nitrite reductase (dNir), and nitric oxide reductase (P450nor), but did not contain ubiquinol-dependent, dissimilatory NO3- reductase (dNar). The denitrification was inhibited by tungstate, an inhibitor of Nar. These results demonstrated occurrence of a novel type of denitrification in C. tonkinense, in which assimilatory type Nar is possibly involved.  相似文献   

12.
Diffusion and reaction of nitric oxide in suspension cell cultures.   总被引:3,自引:0,他引:3       下载免费PDF全文
B Chen  M Keshive    W M Deen 《Biophysical journal》1998,75(2):745-754
A reaction-diffusion model was developed to predict the fate of nitric oxide (NO) released by cells of the immune system. The model was used to analyze data obtained previously using macrophages attached to microcarrier beads suspended in a stirred vessel. Activated macrophages synthesize NO, which is oxidized in the culture medium by molecular oxygen and superoxide (O2-, also released by the cells), yielding mainly nitrite (NO2-) and nitrate (NO3-) as the respective end products. In the analysis the reactor was divided into a "stagnant film" with position-dependent concentrations adjacent to a representative carrier bead and a well-mixed bulk solution. It was found that the concentration of NO was relatively uniform in the film. In contrast, essentially all of the O2- was calculated to be consumed within approximately 2 microm of the cell surfaces, due to its reaction with NO to yield peroxynitrite. The decomposition of peroxynitrite caused its concentration to fall to nearly zero over a distance of approximately 30 microm from the cells. Although the film regions (which had an effective thickness of 63 microm) comprised just 2% of the reactor volume and were predicted to account for only 6% of the NO2- formation under control conditions, they were calculated to be responsible for 99% of the NO3- formation. Superoxide dismutase in the medium (at 3.2 microM) was predicted to lower the ratio of NO3- to NO2- formation rates from near unity to <0.5, in reasonable agreement with the data. The NO3-/NO2- ratio was predicted to vary exponentially with the ratio of O2- to NO release rates from the cells. Recently reported reactions involving CO2 and bicarbonate were found to have important effects on the concentrations of peroxynitrite and nitrous anhydride, two of the compounds that have been implicated in NO cytotoxicity and mutagenesis.  相似文献   

13.
The effect of Ca2+ on NO3- assimilation in young barley (Hordeum vulgare L. var CM 72) seedlings in the presence and absence of NaCl was studied. Calcium increased the activity of the NO3- transporter under saline conditions, but had little effect under nonsaline conditions. Calcium decreased the induction period for the NO3- transporter under both saline and nonsaline conditions but had little effect on its apparent Km for NO3- both in the presence and absence of NaCl. The enhancement of NO3- transport by Ca2+ under saline conditions was dependent on the presence of Ca2+ in the uptake solution along with the salt, since Ca2+ had no effect when supplied before or after salinity stress. Although Mn2+ and Mg2+ enhanced NO3- uptake under saline conditions, neither was as effective as Ca2+. In longer studies, increasing the Ca2+ concentration in saline nutrient solutions resulted in increases in NO3- assimilation and seedling growth.  相似文献   

14.
15.
关于好氧反硝化菌筛选方法的研究   总被引:30,自引:0,他引:30  
采用污泥驯化手段富集好氧反硝化细菌,将得到的驯化污泥分离纯化,共得到105株菌。用测TN的方法对所筛菌株进行初筛,得到25株对TN去除率达到50%以上的菌株。用氮元素轨迹跟踪测定法复筛,证实这25株菌都可以在好氧条件下进行硝酸盐呼吸,其中24株菌的反硝化过程为:NO3^-N→NO2^-N→N2,研究中还发现在反硝化过程中硝酸盐和亚硝酸盐不存在明显竞争被利用的作用。同时还提出了可能实现短程同步硝化反硝化以及在反馈作用的调节下,加快硝化反应速度的观点。  相似文献   

16.
The influence of N-stearoylethanolamine (NSE) on total 11-hydroxycorticosteroids (11-HCS) and testosterone level in the blood of male rats in normal conditions and under the action of 17beta-estradiol (400 mkg/kg of body weight during 3 days) was studied. It was shown that NSE administration per os (50 mg/kg of body weight during 7 days) to intact animals did not change the level of 11-HCS and of testosterone. The administration of NSE to estrogenized male rats decreased the elevated level of 11-HCS and normalized the amount of testosterone in blood. The correction of alterated weight of adenohypophysis and testis of estrogenized male rats compared to control can be a direct evidence of NSE-mediated modelling of the effect on hypothalamic-pituitary hormone system. The effect of NSE in the testis of estrogenized male rats inhibited the process of lipid peroxidation, caused the decrease of the amount of thiobarbituric acid reactive substances and increased the activity of superoxide dismutase and catalase. The NSE showed more expressed antioxidative effect compared to vitamin E. Taking into consideration all above mentioned data we suggested that NSE administration to male rats protected Leydig cells from damage under the increase of estrogen level.  相似文献   

17.
Oxygen requirement for denitrification by the fungus Fusarium oxysporum   总被引:4,自引:0,他引:4  
The effects of dioxygen (O2) on the denitrification activity of the fungus Fusarium oxysporum MT-811 in fed-batch culture in a stirred jar fermentor were examined. The results revealed that fungal denitrifying activity requires a minimal amount of O2 for induction, which is repressed by excess O2. The optimal O2 supply differed between the denitrification substrates : 690 micromol O2 x h(-1) (g dry cell wt.)(-1) for nitrate (NO3-) and about 250 micromol O2 x h(-1) (g dry cell wt.)(-1) for nitrite (NO2-). The reduction of NO3- required more O2 than that of NO2- . With an optimal O2 supply, 80% and 52% of nitrogen atoms in NO3- and NO2-, respectively, were recovered as the denitrification product N2O. These features of F. oxysporum differ from those of bacterial denitrifiers that work exclusively under anoxic conditions. The denitrification activity of F. oxysporum MT-811 mutants with impaired NO3- assimilation was about double that of the wild-type strain, suggesting competition for the substrate between assimilatory and dissimilatory types of NO3- reduction. These results showed that denitrification by F. oxysporum has unique features, namely, a minimal O2 requirement and competition with assimilatory NO3-.  相似文献   

18.
The effects of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) and the NO donor sodium nitroprusside (SNP) on whole body O2 consumption (VO2) were assessed in 16 dogs anesthetized with fentanyl or isoflurane. Cardiac output (CO) and mean arterial pressure (MAP) were measured with standard methods and were used to calculate VO2 and systemic vascular resistance (SVR). Data were obtained in each dog under the following conditions: 1) Control 1, 2) SNP (30 microg. kg-1. min-1 iv) 3) Control 2, 4) L-NAME (10 mg/kg iv), and 5) SNP and adenosine (30 and 600 microg. kg-1. min-1 iv, respectively) after L-NAME. SNP reduced MAP by 29 +/- 3% and SVR by 47 +/- 3%, while it increased CO by 39 +/- 9%. L-NAME had opposite effects; it increased MAP and SVR by 24 +/- 4% and 103 +/- 11%, respectively, and it decreased CO by 37 +/- 3%. Neither agent changed VO2 from the baseline value of 4.3 +/- 0.2 ml. min-1. kg-1, since the changes in CO were offset by changes in the arteriovenous O2 difference. Both SNP and adenosine returned CO to pre-L-NAME values, but VO2 was unaffected. We conclude that 1) basally released endogenous NO had a tonic systemic vasodilator effect, but it had no influence on VO2; 2) SNP did not alter VO2 before or after inhibition of endogenous NO production; 3) the inability of L-NAME to increase VO2 was not because CO, i.e., O2 supply, was reduced below the critical level.  相似文献   

19.
Nitric oxide induces BNIP3 expression that causes cell death in macrophages   总被引:4,自引:0,他引:4  
Nitric oxide (NO) is involved in many physiological processes and also causes pathological effects by inducing apoptosis. It can enhance or suppress apoptosis depending on its concentration and the cell type involved. In this report, we used cDNA microarray analysis to show that SNAP, an NO donor, strongly induces Bcl-2/adenovirus E1B 19kDa-interacting protein 3 (BNIP3) in macrophages. BNIP3 is a mitochondrial pro-apoptotic protein that contains a Bcl-2 homology 3 domain and a COOH-terminal transmembrane (TM) domain. Macrophages activated by LPS/IFN-gamma produce nitric oxide synthase 2 (NOS2) and release endogenous NO. Expression of BNIP3 was also induced in macrophages by LPS/IFN-gamma, and the induction was blocked by a NOS2 inhibitor, S-methyl-isothiourea. Peritoneal macrophages from NOS2-null mice failed to produce BNIP3 in response to LPS/IFN-gamma. We conclude that BNIP3 expression in macrophages is controlled by the intracellular level of nitric oxide. Overexpression of BNIP3 but not of BNIP3 deltaTM, a BNIP3 mutant without the TM domain and C-terminal tail, led to apoptosis of the cells. Promoter analysis showed that the region between -281 and -1 of the 5'-upstream enhancer region of murine BNIP3 was sufficient for NO-dependent expression of BNIP3.  相似文献   

20.
目的探讨外周血癌胚抗原(CEA)、细胞角蛋白19片段(CYFRA21-1)和神经元特异性烯醇化酶(NSE)的检测对肺癌的诊断、病理分型和疗效判断的临床用价值。方法采用化学发光法检测了62例肺癌患者、54例良性肺部疾病患者、36例健康人、40例肺癌患者手术前后血清CEA、CYFRA21-1和NSE的水平。结果肺癌患者手术前血清CEA、CYFRA21-1和NSE的含量明显高于良性肺部疾病组及正常对照组(P0.01)。鳞癌组、腺癌组和小细胞癌组之间肿瘤标志物CEA、CYFRA21-1和NSE水平差异有统计学意义。CEA阳性率以腺癌组最高(84%),CYFRA21-1阳性率以鳞癌组最高(85.2%),NSE阳性率以小细胞癌组最高(80.0%)。手术治疗后未复发转移组CEA、CYFRA21-1和NSE水平低于术前,而复发转移组与术前比变化不显著(P0.05)。结论血清CEA、CYFRA21-1和NSE的检测对不同病理类型肺癌患者的诊断、病情检测及疗效判断有较好的临床参考价值。  相似文献   

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