摘要:

Human T-cell lines and normal lymphocytes persistently or acutely co-infected with the human immunodeficiency virus type 1 (HIV-1) and mycoplasmas were found to release hydrogen peroxide (H2O2), a likely cause of oxidative stress in these cells. The spectrofluorometric measurement of H2O2 release from these cells, using the scopoletin fluorescence quenching technique, gave values of 16-84 p moles/106cells/min. In CEM cells, H2O2was released only when acutely co-infected with HIV-1 and mycoplasmas, and not when infected with either organism alone. Anti-mycoplasmal antibiotics strongly reduced H2O2release, and improved cell viability without blocking virus replication. These results suggest that the simultaneous infection by HIV-I and mycoplasma leads to the release of H2O2, a toxic and potentially lethal metabolite, whichin vivomay contribute to HIV-1 pathogenicity.

ISSN:1071-5762    

DOI:10.3109/10715769509064034

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

Arthritis develops in DBA/1xB10A(4R) mice and Wistar rats upon intraplantar injection of potassium peroxochromate (K3CrO8), and is here quantified by whole blood chemiluminescence (CL) and pertechnetate-imaging (99mTcO4−), and related to overt disease symptoms (the arthritis index). During the aqueous decay of K3CrO8to chromate (VI), the chromium(V)-bound oxygen is released as superoxide, hydroxyl radicals, singlet oxygen and hydrogen peroxide, the same reactants, which are produced by activated phagocytes during inflammation. Reactive oxygen species (ROS) trigger the breakdown of the sulfhydryl-dependent antioxidant defence system and induce the nuclear factor kappa B-dependent expression of pro-inflammatory cytokines, which prime phagocytic NADPH oxidases to the enhanced production of ROS. During both the acute inflammatory response and the onset of the secondary response in non-injected paws, the phorbolester-stimulated ROS production of phagocytes was significantly enhanced (p<0.001) and correlated well to the arthritis index (r=0.797) and the uptake of99mTcO4−into inflamed joints. Chromate(VI), formed during the decay of K3CrO8, contributes to the progression of arthritis by inhibition of glutathione reductase, thereby increasing intracellular H2O2concentrations. In addition, Cr(VI) reduced to Cr(V) by ascorbate, catalyzes hydroxyl radical production in the presence of hydrogen peroxide. A stable loop forms, in which ROS, continuously produced by Cr(VI)/Cr(V) redox-cycling, drive the primary response into chronic self-perpetuating inflammation. We see the main application of K3CrO8-induced arthritis and its assessment by both99mTcO4−imaging and chemiluminescent immunosensoring of phagocytic activity in unseparated blood as for the rapid screening of novel anti-rheumatic drugs and treatments.

ISSN:1071-5762    

DOI:10.3109/10715769509064035

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

The competition method in which the Fenton reaction is employed as an OH radical generator and deoxyribose as a detecting molecule, has been used to determine the rate constants for reactions of the OH radical with its scavengers. Nonlinear competition plots were obtained for those scavengers which reacted with the Fenton reagents (Fe2+or H2O2). Ascorbic acid is believed to overcome this problem. We have investigated the kinetics of deoxyribose degradation by -OH radicals generated by the Fenton reaction in the presence of ascorbic acid, and observed that the inclusion of ascorbic acid in the Fenton system greatly increased the rate of OH radical generation. As a result, the interaction between some scavengers and the Fenton reagents became negligeable and linear competition plots of A7A vs scavenger concentrations were obtained. The effects of experimental conditions such as, the concentrations of ascorbic acid, deoxyribose, H2O2and Fe2+-EDTA, the EDTA/Fe2+ratio as well as the incubation time, on the deoxyribose degradation and the determination of the rate constant for mercaptoethanol chosen as a reference compound were studied. The small standard error, (6.76±0.21)±' 109M−1s−1observed for the rate constant values for mercaptoethanol determined under 13 different experimental conditions, indicates the latter did not influence the rate constant determination. This is in fact assured by introducing a term, kx, into the kinetic equation. This term represents the rate of-OH reactions with other reagents such as ascorbic acid, Fe2+-EDTA, H2O2etc. The agreement of the rate constants obtained in this work with that determined by pulse radiolysis techniques for cysteine, thiourea and many other scavengers, suggests that this simple competition method is applicable to a wide range of compounds, including those which react with the Fenton reagents and those whose solubility in water is low.

ISSN:1071-5762    

DOI:10.3109/10715769509064036

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

In the rabbit, an acute inflammatory reaction triggered by the subcutaneous administration of turpentine induces in hepatic tissues an oxidative stress, as well as a decrease in activity of enzymatic scavengers of reactive oxygen species (ROS). The objective of this study was to investigate, the repercussions of a local inflammatory reaction on the antioxidant capacity and markers of systemic oxidative stress in plasma. To this purpose, rabbits received a s.c. injection of turpentine (5 mL/kg) or NaCl 0.9% (w/v). Blood samples were collected at different times during the 48 hours of the experiment to evaluate: firstly, the antilipoperoxidant activity of plasma by measuring the inhibition of autoxidation of brain homogenate, and the concentrations of tocopherol and ascorbic acid; secondly, the severity of oxidative stress in plasma by assaying the concentration of thiobarbituric acid reactive substances (TBARS), and the concentration of ascorbyl radical. The results show that the antilipoperoxidant capacity of plasma gradually increased to be 167% higher than baseline values (p<0.05) after 48 hours of experiment.α-Tocopherol and ascorbic acid levels increased by 49% and 80%, respectively (p<0.05) during the first 24 hours. Lipid peroxidation continuously increased to be 98% higher than baseline values(p<0.05) at 48 hours, while ascorbyl radical levels were not modified(p<0.05). In summary, an acute local inflammatory reaction causes a steady progression of oxidative stress, while it stimulates the antilipoperoxidant activity of plasma, to which a-tocopherol and ascorbic acid appear to contribute, essentially early in the inflammation.

ISSN:1071-5762    

DOI:10.3109/10715769509064037

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

8-OH-deoxyguanosine can diminish the ability of the restriction endonucleasesHpaII andMspI to cleave DNA. The exact position of the adduct within the recognition site appears to determine the extent of the effect.

ISSN:1071-5762    

DOI:10.3109/10715769509064038

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

A prominent feature of human atherosclerosis is the lipid-laden foamy macrophage, which often also contains the insoluble pigment, ceroid. The culture of macrophage-like cells, P388Dis, with artificial lipoproteins composed of cholesteryl linoleate (CL) and bovine serum albumin (BSA) results in foam cell formation with lipoprotein uptake and the intracellular accumulation of ceroid. Ceroid accumulation is accompanied by the oxidation of the cholesterol ester as monitored by gas chromatography. The sodium salt of diethyldithio-carbamic acid (DDC) at 1-5μM effectively inhibited lipoprotein uptake, cholesteryl linoleate oxidation and ceroid accumulation in cultures of P388D1. Further studies showed that intracellular ceroid accumulation appeared to require the presence of cystine in the medium. Lipoprotein oxidation by this macrophage-like cell therefore appears to involve a mechanism dependent on cystine metabolism which is consistent with previous reports of macrophage-mediated lipoprotein oxidation. Studies on CL/BSA-induced ceroid accumulation in human monocytes also showed that DDC behaved in much the same manner. This inhibitory effect of DDC on foam cell formation, often considered a primary event of atherosclerosis, at concentrations as low as 1μM, suggests the need for further, more comprehensive, studies on this compound's activities.

ISSN:1071-5762    

DOI:10.3109/10715769509064039

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

The influence of fatty acid (FA) micelles on cytochrome c(cyt.c) reduction and nitroblue tetrazolium (NBT) reduction assays for SOD activity, which continue to be widely used, has been studied. In the presence of FA micelles, the use of cyt.c reduction assay was found to overestimate the real activity of SOD. This effect is attributed to the following reasons. 1. The FA micelles lead to the denaturation of cyt.c, which gives rise to suppression of the reactivity of ferricyt.c (cyt.c(ox)) towards O2−. Furthermore, this denaturation increases the reoxidation rate of ferrocyt.c, and consequently the reoxidation causes a decreased rate of cyt.c(ox) reduction. 2. Positively charged cyt.c(ox) interacts with negatively charged FA micelles, and so cyt.c(ox) on the surface of FA micelles reacts less with negatively charged O2−because of electrostatic repulsion. Also in NBT reduction assay using a positively charged probe molecule, FA micelles cause the appearance of enhancement of SOD activity, due to suppression of the reactivity of NBT towards O2−by electrostatic repulsion. However, in both chemiluminescence assay using the uncharged probe molecule and LDH-N ADH assay using the negatively charged probe molecule, FA micelles cannot influence the assays of the SOD activity, because the micelles do not interact electrostatically with probe molecules.

ISSN:1071-5762    

DOI:10.3109/10715769509064040

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

The unique capabilities of EPR spin trapping of nitric oxide based on a ferrous-dithiocarbamate spin trap have been demonstrated in a study verifying the source of the nitrogen and oxygen atoms in nitric oxide produced from activated macrophages. Spin trapping experiments were performed during nitric oxide generation from activated mouse peritoneal macrophages using the ferrous complex of N-methyl D-glucam-ine dithiocarbamate as a spin trap. When15N-substituted arginine was given to the activated macrophages in the presence of the spin trap, a characteristic EPR spectrum of the nitric oxide spin adduct was obtained, which indicates the presence of thel5N atom in the nitric oxide molecule. The hyperfine splitting (hfs) constant of thel5N nucleus was 17.6 gauss. Whenl7O-containing dioxygen (55%) was supplied to the medium, an EPR spectrum consistent with the“O-substituted nitric oxide spin adduct was observed in the composite spectrum. The hfs of“O was estimated to be 2.5 gauss. Thel4NO spin adduct observed after prolonged incubation in the medium which contains [l5N]L-arginine as the only extracellular source of arginine demonstrates that arginine is recycled through its metabolite in activated macrophages.

ISSN:1071-5762    

DOI:10.3109/10715769509064041

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

ISSN:1071-5762    

DOI:10.3109/10715769509064042

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor