共查询到20条相似文献,搜索用时 31 毫秒
1.
Kenneth Hensley Quentin N. Pye Michael L. Maidt Charles A. Stewart Kent A. Robinson Fatima Jaffrey Robert A. Floyd 《Journal of neurochemistry》1998,71(6):2549-2557
Abstract: Mitochondrial complexes I, II, and III were studied in isolated brain mitochondrial preparations with the goal of determining their relative abilities to reduce O2 to hydrogen peroxide (H2 O2 ) or to reduce the alternative electron acceptors nitroblue tetrazolium (NBT) and diphenyliodonium (DPI). Complex I and II stimulation caused H2 O2 formation and reduced NBT and DPI as indicated by dichlorodihydrofluorescein oxidation, nitroformazan precipitation, and DPI-mediated enzyme inactivation. The O2 consumption rate was more rapid under complex II (succinate) stimulation than under complex I (NADH) stimulation. In contrast, H2 O2 generation and NBT and DPI reduction kinetics were favored by NADH addition but were virtually unobservable during succinate-linked respiration. NADH oxidation was strongly suppressed by rotenone, but NADH-coupled H2 O2 flux was accelerated by rotenone. α-Phenyl- N-tert -butyl nitrone (PBN), a compound documented to inhibit oxidative stress in models of stroke, sepsis, and parkinsonism, partially inhibited complex I-stimulated H2 O2 flux and NBT reduction and also protected complex I from DPI-mediated inactivation while trapping the phenyl radical product of DPI reduction. The results suggest that complex I may be the principal source of brain mitochondrial H2 O2 synthesis, possessing an "electron leak" site upstream from the rotenone binding site (i.e., on the NADH side of the enzyme). The inhibition of H2 O2 production by PBN suggests a novel explanation for the broad-spectrum antioxidant and antiinflammatory activity of this nitrone spin trap. 相似文献
2.
The effects of physical and chemical factors on the production of H2 O2 from Escherichia coli cells were studied. When 20 mmol 1-1 Tris-HCl buffer was used for this purpose the electron transport system (ETS) showed the highest activity at pH 7.6-8.2. KCN promoted the production of H2 O2 from E. coli cells, and the optimum concentration was changed in different reaction times and pH values. Glucose, 5 mg ml-1 , increased the ETS activity about twofold. The other substrates and surfactants did not increase the chemiluminescence intensity. NaNO2 and Na2 SO4 in inorganic salts significantly reduced the ETS activity above 70%. In addition, the optimum temperature for the production of H2 O2 was 30°C in this study. When glucose (5 mg ml-1 ) and KCN (0.2 mmol 1-1 ) were added to the reaction buffer containing 0.5 mmol 1-1 menadione, the detectable minimum cell densities (averages of triplicate assay) of E. coli, Enterobacter cloacae and Serratia marcescens were 5 times 103 cells ml-1 , 104 cells ml-1 and 104 cells ml-1 respectively. 相似文献
3.
Abstract Production of hydrogen peroxide by mouse peritoneal macrophages activated with Corynebacterium parvum was induced by incubating the cells with opsonised zymosan. H2 O2 release was reduced by 47% when macrophages were preincubated with opsonised sheep erythrocytes. A significant decrease also occurred when the cells were preincubated with heat-denatured haemoglobin, but not when preincubated with opsonised erythrocyte ghosts, even though the latter were taken up by the macrophages. The ability of macrophages in an infected lesion to destroy microorganisms may therefore be impaired by ingestion of extravasated erythrocytes. 相似文献
4.
A new biochemical marker for aluminium tolerance in plants 总被引:1,自引:0,他引:1
Al was shown to elicit the induction of several pathogenesis-related genes, suggesting that a common signalling pathway may be involved in the early response to Al and pathogens. However, we found no evidence of oxidative burst involving either H2 O2 or O2 – during the first hours of Al exposure distinguishing the early response to Al from a common response to pathogen infection. We identified a strong superoxide dismutase insensitive nitro blue tetrazolium (NBT) reduction activity in the root tips of control plants. This activity was rapidly inhibited by Al exposure in the meristematic/distal transition zones of roots in all species examined. In wheat ( Triticum aestivum ), the inhibition of NBT reduction occurred in less than 1 min in vivo suggesting that Al either directly blocks an enzyme responsible for NBT reduction, or affects a signal pathway involved in the regulation of this activity. The sensitivity of NBT reduction to KCN and NaN3 suggests that an enzymatic, rather than a chemical reaction is involved. In tolerant plants, the inhibition of NBT reduction caused by Al was reversed within 24 h of exposure. The level of recovery was a function of the degree of Al tolerance. We show that NBT reduction is a simple biochemical marker allowing the rapid identification of tolerant individuals within a segregating population. 相似文献
5.
D.A. DIONYSIUS, P.A. GRIEVE AND A.C. VOS. 1992. Components of the lactoperoxidase system were measured during incubation in Isosensitest broth, with enzymatic (glucose oxidase, GO) or chemical (sodium carbonate peroxyhydrate, SCP) means to generate H2 O2 . When low levels of thiocyanate (SCN- ) were used in the GO system, H2 O2 was detected and lactoperoxidase (LP) was inactivated when SCN- was depleted. With 10-fold higher SCN- , LP remained active and H2 O2 was not detectable. The oxidation product of the LP reaction, most likely hypothiocyanite, was present in low concentrations. When SCP was used for the immediate generation of H2 O2 in a system employing low SCN- , half the LP activity was lost within minutes but thereafter it remained stable. Low concentrations of oxidation product were measured and H2 O2 was not detected during the course of the experiment. At high SCN- levels, relatively high concentrations of oxidation product were produced immediately, with H2 O2 undetectable. The results suggest that the final product of the LP reaction depends on the method of H2 O2 generation and the relative proportions of the substrates. Antibacterial activity of the two LPS was tested against an enterotoxigenic strain of Escherichia coli. Both systems showed bactericidal activity within 4 h incubation at 37°C. 相似文献
6.
K. Toté D. Vanden Berghe S. Levecque E. Bénéré L. Maes P. Cos 《Journal of applied microbiology》2009,107(2):606-615
Aims: Development of the resazurin microplate method (RMM) as a novel test system for the evaluation of the antimicrobial activity of antiseptics and disinfectants. The validated RMM was subsequently applied for the evaluation of hydrogen peroxide (H2 O2 ) and stabilized H2 O2 combination products.
Methods and Results: The European Committee for Standardization prescribes the plate count challenge test (PCCT) for antiseptic and disinfectant efficacy testing. This protocol was adapted to a microplate-based assay, using resazurin as viability indicator. The RMM was as accurate as the PCCT, had an identical detection limit and showed high intermediate precision. Using the validated RMM, it was shown that H2 O2 combined with silver possessed a higher bactericidal and fungicidal activity compared to native H2 O2 with and without glycerol.
Conclusions: Validation showed that the RMM may replace the PCCT. When applying the RMM, H2 O2 combined with silver was clearly a more potent disinfectant compared to H2 O2 in killing bacteria and fungi.
Significance and Impact of the Study: The RMM is easier to use for antimicrobial efficacy testing of antiseptics and disinfectants. As the RMM is in accordance with the norms of the European Committee for Standardization, it may become a more cost-effective alternative to the more laborious PCCT reference method. H2 O2 with silver may replace native H2 O2 to increase overall disinfection efficiency. 相似文献
Methods and Results: The European Committee for Standardization prescribes the plate count challenge test (PCCT) for antiseptic and disinfectant efficacy testing. This protocol was adapted to a microplate-based assay, using resazurin as viability indicator. The RMM was as accurate as the PCCT, had an identical detection limit and showed high intermediate precision. Using the validated RMM, it was shown that H
Conclusions: Validation showed that the RMM may replace the PCCT. When applying the RMM, H
Significance and Impact of the Study: The RMM is easier to use for antimicrobial efficacy testing of antiseptics and disinfectants. As the RMM is in accordance with the norms of the European Committee for Standardization, it may become a more cost-effective alternative to the more laborious PCCT reference method. H
7.
The (C2 H4 + H2(C2 H2 ) )/15 N2 ratios of 15 clover- Rhizobium symbionts. soybean, and black medick symbionts were measured. Relative efficiency based on the C2H4 production and on 15 N2 incorporation were compared, and in most symbionts there was little difference between the two measures of relative efficiency. Total measurable electron flux through nitrogenase during acetylene reduction and 15 N2 incorporation were nearly equal for most symbionts studied. The relative efficiency and the (C2 H4 + H2(C2 H2 ) )/15 N2 ratio showed an inverse correlation. Use of this ratio appears preferable to use of the ratio of C2H2 reduction/N2 reduction. Some evolution of H2 was observed in the presence of C2 H2 . 相似文献
8.
The lactoperoxidase system (LPS), a natural bactericidal system in milk, was investigated for its activity against salmonellas in vivo and in vitro. In acidified raw milk, in which the LPS was supplemented with an exogenous supply of H2 O2 , the numbers of salmonellas decreased rapidly. Different salmonella serotypes were affected to the same extent; rough strains, however, were more susceptible than smooth strains. When calves were fed on fresh milk, containing the LPS, and challenged with Salmonella typhimurium in doses of either 109 or 1010 , the clinical findings and salmonella excretion patterns were similar to those of control calves fed on heated milk. It was concluded that further studies, perhaps in the field, are necessary to evaluate LPS as a possible non-antibiotic system to control salmonellosis. 相似文献
9.
Changes in catalase activity and hydrogen peroxide concentration in plants in response to low temperature 总被引:6,自引:0,他引:6
Taxicity of oxygen species such as free radicals and H2 O2 has been invoked to explain a number of degradative processes in plants, most involving photo-oxidation. Since catalase is a major protectant against accumulation and toxicity of H2 O2 , we examined alterations in catalase activity in several plant species ( Pisum sativum L. cv. Greenfeast, Vigna radiata (L.) R. Wilcz, Cucumis sativus L. cv. Heinz Pickling, and Passiflora spp.) during chilling, and compared this change to change in H2 O2 content. Catalase activity was reduced in a range of chilling sensitive and tolerant species by exposure to low temperature. This reduction in catalase activity correlated better with the onset of visible symptoms than with the treatment itself. Visible injury in turn was dependent on light and temperature differences. Hydrogen peroxide concentrations invariably decreased with low temperatures.
Reduction in catalase activity therefore does not necessarily imply accumulation of H2 O2 to damaging levels. The absence of a clear inverse relationship between catalase activity and H2 O2 concentration suggests the continued activity of other reactions that remove H2 O2 and these may be important in the tolerance of plants to oxidative attack. Loss of catalase activity may result from the inability of damaged peroxisomal membranes to transport catalase precursors into the peroxisome. 相似文献
Reduction in catalase activity therefore does not necessarily imply accumulation of H
10.
Abstract Bacteroides fragilis Bf-2 cells were more sensitive to far-UV radiation, N -methyl- N '-nitrosoguanidine, ethylmethane sulphonate, acriflavine and mitomycin C under aerobic conditions than under anaerobic conditions. The opposite effect was observed with H2 O2 -treated cells and exposure to O2 enhanced the survival of H2 O2 -treated cells. Pretreatment of cells with sublethal concentrations of H2 O2 also increased the survival of H2 O2 -treated cells. Reactivation of UV- and X-irradiated and methylmethane sulphonate and H2 O2 -treated phage b-1 was induced by O2 and H2 O2 in B. fragilis . 相似文献
11.
Is hydrogen peroxide a second messenger of salicylic acid in systemic acquired resistance? 总被引:18,自引:1,他引:17
Urs Neuenschwander Bernard Vernooij Leslie Friedrich Scott Uknes Helmut Kessmann John Ryals 《The Plant journal : for cell and molecular biology》1995,8(2):227-233
Elevated levels of salicylic acid (SA) are required for the induction of systemic acquired resistance (SAR) in plants. Recently, a salicylic acid-binding protein (SABP) isolated from tobacco was shown to have catalase activity. Based on this finding elevated levels of hydrogen peroxide (H2 O2 ) were postulated to act as a second messenger of SA in the SAR signal transduction pathway. A series of experiments have been carried out to clarify the role of H2 O2 in SAR-signaling. No increase of H2 O2 was found during the onset of SAR. Induction of the SAR gene, PR-1, by H2 O2 and H2 O2 -inducing chemicals is strongly suppressed in transgenic tobacco plants that express the bacterial salicylate hydroxylase gene, indicating that H2 O2 induction of SAR genes is dependent on SA accumulation. Following treatment of plants with increasing concentrations of H2 O2 , a dose-dependent accumulation of total SA species was found, suggesting that H2 O2 may induce PR-1 gene expression through SA accumulation. While the results do not support a role for H2 O2 in SAR signaling, it is suggested that SA inhibition of catalase activity may be important in tissues undergoing a hypersensitive response. 相似文献
12.
The effect of hydrogen peroxide on Salmonella typhimurium in whole egg was evaluated. The bactericidal effects observed on the test organism at 5° and 20°C were found to be similar. There was a 99% kill in the presence of 0°5% and 1°0% H2 O2 . Addition of the test organism and H2 O2 after pre-heating the egg material at 40°C for 15 min caused a rapid kill which was 10000-fold greater than that produced by H2 O2 alone. 相似文献
13.
14.
Hydroxyl Radicals Generated In Vivo Kill Neurons in the Rat Spinal Cord: Electrophysiological, Histological, and Neurochemical Results 总被引:1,自引:0,他引:1
Abstract: We have used microdialysis to establish an experimental model to characterize mechanisms whereby released substances cause secondary damage in spinal cord injury. We use this model here to characterize damaging effects of the hydroxyl radical (OH') in vivo in the spinal cord. OH'was generatad in vivo by pumping H2 O2 and FeCI2 /EDTA through parallel microdialysis fibers inserted into the spinal cord. These agents mixed in the tissue to produce OH'by Fenton's reaction. Two types of control experiments were also conducted, one administering only 5 m M H2 O2 and the other only 0.5 m M FeCI2 /0.82 m M EDTA. During administration of these chemicals, electrical conduction was recorded as one test for deterioration. OH'blocked conduction completely in 2.5-5 h and Fe2+ /EDTA partly blocked conduction, but H2 O2 alone did not cause detectable blockage. Histological examination supported the hypothesis that neurons were killed by OH', as Fe2+ /EDTA and H2 O2 alone did not destroy significant numbers of neurons. OH', H2 O2 , and Fe2+ all caused gradual increases in extracellular amino acid levels. These results are consistent with Fe2+ -catalyzed free radical generation playing a role in tissue damage upon spinal cord injury. 相似文献
15.
16.
Heide J.K. Slade J.Petra Schumann David T. Jones David R. Woods 《FEMS microbiology letters》1983,20(3):401-405
Abstract Reactivation of UV-irradiated phage b-1 was induced by H2 O2 and UV in Bacteroides fragilis . The characteristics of H2 O2 and UV induced phage reactivation differ from a previously reported oxygen induced reactivation system. The survival of B. fragilis cells after UV irradiation was also increased by pretreatment with H2 O2 . DNA synthesis was not inhibited in the host cells exposed to H2 O2 concentrations which induced phage reactivation. The pattern of DNA degradation and synthesis after UV irradiation with and without H2 O2 differed from the effect of O2 on DNA synthesis in irradiated B. fragilis cells. 相似文献
17.
Acanthamoeba spp. are free-living amebae associated with amebic keratitis and chronic granulomatous amebic encephalitis. The present studies were undertaken to compare the pathogenicity of three species of Acanthamoeba in B6 C3 F1 mice after intranasal challenge with Acanthamoeba-induced cytopathogenicity for different macrophage populations. The ability of murine macrophage cell lines and activated murine peritoneal macrophages to lyse Acanthamoeba has been assessed by coincubating macrophages with 3 H-uridine labeled amebae. Conversely, destruction of macrophages by Acanthamoeba was determined by measuring the release of chro-mium-51 from radiolabeled macrophages. Acanthamoeba culbensoni , which is highly pathogenic for mice, destroys macrophage cultures in vitro. Activated primary peritoneal macrophages were more resistant to Acanthamoeba -mediated destruction than macrophage cell lines activated in vitro. Activated macrophages were capable of limited destruction of Acanthamoeba polyphaga and Acanthamoeba castellanii. Acanthamoeba -specific antibodies increased the amebicidal activity of activated macrophages. Macrophage-mediated destruction was by contact-dependent cytolysis and by ingestion of amebae. Conditioned medium obtained from macrophage cultures after treatment with lipopolysaccharide and interferon gamma was neither cytolytic nor cytostatic for Acanthamoeba spp. Purified recombinant cytokines including tumor necrosis factor α. interleukin 1α, and interleukin 1β, alone or in combination, were not cytolytic for Acanthamoeba trophozoites. 相似文献
18.
Elimination of calcium ions from the medium of undifferentiated cell cultures of Digitalis thapsi increased cardenolide production and induced extracellular H2 O2 accumulation, as measured by the quenching of pyranine fluorescence. The addition of catalase reduced the response and the inclusion of superoxide dismutase enhanced the loss of fluorescence. This suggested that, besides H2 O2 , the superoxide anion was also formed before dismutating to H2 O2 . Additionally, exogenous H2 O2 or superoxide dismutase stimulated cardenolide production whereas the addition of catalase markedly reduced it. These results point to a connection between H2 O2 and cardenolide formation. The absence of calcium did not alter the levels of lipid peroxidation products; however, changes in the antioxidant system of D. thapsi cells were observed. Catalase activity was extremely low in control cultures and remained unaltered upon calcium elimination. Ascorbate peroxidase activity was not modified in calcium-free cultures. By contrast, calcium deprivation stimulated superoxide dismutase activity and strongly inhibited glutathione reductase activity. Also, a significant decrease in reduced glutathione was observed. These responses were emulated by treatment of the cultures with the glutathione biosynthesis inhibitor buthionine sulfoximine and by ethyleneglycol-bis-β-aminoethyl ether and LaCl3 . All these results indicate that the depletion of extracellular calcium induces changes in the redox state of cells and suggest that this alteration stimulates cardenolide formation in D. thapsi cultures. 相似文献
19.
Prostaglandin H Synthetase-Mediated Metabolism of Dopamine: Implication for Parkinson's Disease 总被引:2,自引:1,他引:1
† Michael B. Mattammal ‡§Randy Strong †Vijaya M. Lakshmi ¶Hyung D. Chung #Alan H. Stephenson 《Journal of neurochemistry》1995,64(4):1645-1654
Abstract: Differences in prostaglandin H synthetase (PHS) activity in the substantia nigra of age- and post-mortem interval-matched parkinsonian, Alzheimer's, and normal control brain tissue were assessed. Prostaglandin E2 (PGE2 , an index of PHS activity) was higher in substantia nigra of parkinsonian brain tissue than Alzheimer's or control tissue. Incubation of substantia nigra slices with arachidonic acid (AA) increased PGE2 synthesis. Dopamine stimulated PHS synthesis of PGE2 . [3 H]Dopamine was activated by PHS to electrophilic intermediate(s) that covalently bound to DNA, microtubulin protein, bovine serum albumin, and sulfhydryl reagents. When AA was replaced by hydrogen peroxide, PHS/H2 O2 -supported binding proceeded at rates similar to those observed with PHS/AA. Indomethacin and aspirin inhibited AA-mediated cooxidation of dopamine but not H2 O2 -mediated metabolism. PHS-mediated metabolism of dopamine was not affected by monoamine oxidase inhibitors. Substrate requirements and effects of specific inhibitors suggest cooxidation of dopamine is mediated by the hydroperoxidase activity of PHS. 32 P-postlabeling was used to detect dopamine-DNA adducts. PHS/AA activation of dopamine in the presence of DNA resulted in the formation of five dopamine-DNA adducts, i.e., 23, 43, 114, 70, and 270 amol/µg DNA. DNA adduct formation was PHS, AA, and dopamine dependent. PHS catalyzed cooxidation of dopamine in dopaminergic neuronal degeneration is discussed. 相似文献
20.
Abstract The temperature profiles have been determined for O2 reduction by activating substrates for whole cells and cell extracts of the psychrophilic, obligately anaerobic bacterium, strain B6, belonging to the Bacteroidaceae. The profiles were similar whether the cells were grown at 15 or 1°C, and also for cells harvested in the exponential or stationary phase. The H2 O producing pyruvate oxidase displayed in cell-free extracts a considerably higher activity than the H2 O2 producing NADH and NADPH oxidases at all temperatures in the range 30–1°C, and characteristically makes up a larger proportion of the total O2 reduction capacity the lower the temperature. It thus seems that the O2 scavenging property of the pyruvate oxidase, postulated to be utilized in a defense mechanism against the detrimental effects of the H2 O2 producing pyridine nucleotide oxidases, is particularly well adapted to function at the low temperatures of the Barents Sea, from which this obligately anaerobic organism originates. 相似文献