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PubMed2000

Association of alpha-interferon and acetyl cysteine in patients with chronic C hepatitis.

BACKGROUND: Numerous experimental findings have underlined the relationships between liver damage and production of oxygen-derived free radicals during inflammation. In chronic hepatitis C liver disease this damage may be attributed to altered oxide-reductive balance and glutathione (GSH) depletion. Moreover, it may be linked to chronic inflammation provoked by the replicative activity of the hepatitis C virus and its relationships with immune system cells. Our aim was to assess the effects of combined IFN + NAC treatment to compare the effects of interferon alpha-n1 associated with N-acetyl cysteine treatment with the results observed using interferon therapy alone. METHODS EXPERIMENTAL DESIGN: prospective randomised study. SETTING: Ambulatory and hospitalised care. PATIENTS: 77 selected patients affected by chronic C hepatitis. INTERVENTIONS: our patients were investigated by laboratory tests (ALT values, RIBA test, HCV-RNA, oxide-reductive balance), liver biopsy and liver US. The recruited subjects were treated with interferon and N-acetyl cysteine or with interferon alone. RESULTS: Our findings confirmed the presence of oxidative stress in patients with chronic hepatitis C and showed earlier relapse in patients treated with interferon alone. The difference between the results in patients treated with interferon and N-acetyl cysteine and those on interferon alone was significant. CONCLUSIONS: The good results and absence of side effects in patients treated with interferon + N-acetyl cysteine recommend wider use of this association.

Acetylcysteine↗
PubMed2004

Oxygen sensing and oxidant/redox-related pathways.

What is the nature of the oxygen sensor(s) and how do organisms sense variations in oxygen? A progressive rise of oxidative stress due to the altered reduction-oxidation (redox) homeostasis appears to be one of the hallmarks of the processes that regulate gene transcription. Dynamic changes in oxygen homeostasis and its close association with redox equilibrium, therefore, constitute a signaling mechanism for the expression/activation of oxygenes. This variation subsequently regulates the compartmentalization and functioning of HIF-1alpha and NF-kappaB. In addition, oxygen-evoked regulation of HIF-1alpha and NF-kappaB is closely coupled with intracellular redox state, such that modulating redox equilibrium affects their responsiveness at the molecular level (expression/transactivation). Interestingly, are these particular transcription factors potential oxygen sensors? The basic components of the intracellular oxidative/redox machinery and its crucial regulation of oxygen- and redox-sensitive transcription factors may help understand the network of oxygen sensing mechanisms and redox-related pathways.

Adaptation, Physiological↗
PubMed1985

Differential effect of thiol oxidants on the chloroplast H+-ATPase in the light and in the dark.

The effect of thiol oxidants on the light-activated H+-ATPase has been studied in freshly broken and intact chloroplasts. The following observations were made: (i) in chloroplasts which are osmotically shocked after light activation, ferricyanide stimulates the deactivation of the enzyme in the dark, but has little effect in the light; (ii) similarly, o-iodosobenzoate is a most efficient deactivator of the ATPase in intact chloroplasts in the dark but not in the light; (iii) the activated ATPase becomes sensitive to oxidants in the light upon the addition of an uncoupler; (iv) the oxidant-induced deactivation in the dark dominates the stabilizing effect of pyrophosphate or ADP plus Mg2+; (v) full deactivation of the ATPase by dark adaptation or by oxidants does not affect the rate of photophosphorylation under saturating conditions. A model is suggested in which two kinds of conformational changes are involved in the regulation of the ATPase: those induced by the trans-membrane-proton gradient and those by oxidation-reduction of the enzyme. These changes result in the preferential interaction with thiol reductants in the light but with thiol oxidants in the dark.

Chloroplasts↗
PubMed1996

[Preliminary study of microbiocide effect and its mechanism of electrolyzed oxidizing water].

Electrolyzed Oxidizing water (EO Water) is characterized by possessing higher oxidizing reduction potential (ORP), lower pH value and oxidizing potential. Under conditions of free organic matter, it was tested for microbiocide efficacy in laboratory. The results showed that EO water could completely kill all of the staphylococcus aureus and E. coli within 15 seconds, while for completely killing of spores of Bacillus subtilis Var. niger it would take 10 min. When it was used to destroy the antigenicity of HBsAg, 30 seconds was needed. The ORP and pH values of EO water were not obviously changed when stored in room-temperature with, airtight and light-free conditions for three weeks. Distilled water and physiological saline had little influence on the ORP and pH value of EO water, but organic matters and phosphates had greater influence upon the two values.

Bacillus subtilis↗
PubMed1992

[Asporogenic anaerobic thoracic empyema--an experimental model for anaerobic thoracic empyema in rabbits].

Sterile pleural effusion was induced by intrapleural administration of turpentine, and empyema was induced by direct intrapleural inoculation of bacteria in rabbits. Experimental models of anaerobic thoracic empyema were successfully made in this study, using Escherichia coli, Peptostreptococcus asaccharolyticus, Bacteroides fragilis, using the following methods; (1) a single bacterium inoculation of, a) E. coli, b) P. asaccharolyticus, c) B. fragilis, (2) simultaneous inoculations with an aerobe and an anaerobe, a) E. coli + P. asaccharolyticus, b) E. coli + B. fragilis. (3) an anaerobic inoculation 5 days after an aerobic inoculation, a) P. asaccharolyticus inoculation 5 days after E. coli inoculation, b) B. fragilis inoculation 5 days after E. coli inoculation. The developments of several parameters (sialic acid levels, glucose levels, oxidation-reduction potential levels, bacterial counts and WBC counts in the pleural fluid and so on) were measured in each group. There was little difference of the rate of incidence of empyema between each group. Empyema was highly induced even by a single anaerobe inoculation. The following tendencies were observed in development of parameters: (1) sialic acid levels and oxidation-reduction potential levels were decreased only in the conditions being associated by B. fragilis infections. (2) in mixed infections of E. coli and anaerobes, bacterial counts of E. coli increased in number in the late phases of the infections probably by the influences of anaerobes. The experiments of groups (2) and (3) were designed for demonstrations of biphasic infections between aerobes and anaerobes, but it turned out that quite unexpected results were seen in these models.

Animals↗
PubMed2002

REDOX regulation of early embryo development.

Preimplantation embryonic development is associated with a change in preference in energy metabolism pathways. Although oxidative phosphorylation is obligatory in most species throughout preimplantation development, an increasing role for energy derived from glycolysis is associated with compaction and blastulation. Such a shift in metabolic pathway preference is desirable as the embryo faces an increasingly hypoxic environment in utero. We hypothesize that this shift in metabolic preference is associated with a change in the reduction-oxidation (REDOX) state within the embryo, affecting not only the energy production required for development, but also the activity of REDOX-sensitive transcription factors, which may alter gene expression patterns. Shifts in intracellular REDOX state may also contribute to spatial differences in cell activity, especially after compaction, and perhaps even major embryonic events such as fertilization, genome activation and cellular differentiation.

Animals↗
PubMed2004

Stereospecificity of horseradish peroxidase.

We report here on the stereospecificity observed in the action of horseradish peroxidase (HRPC) on monophenol and diphenol substrates. Several enantiomers of monophenols and o-diphenols were assayed: L-tyrosinol, D-tyrosinol, L-tyrosine, DL-tyrosine, D-tyrosine, L-dopa, DL-dopa, D-dopa, L-alpha-methyldopa, DL-alpha-methyldopa, DL-adrenaline, D-adrenaline, L-isoproterenol, DL-isoproterenol and D-isoproterenol. The electronic density at the carbon atoms in the C-1 and C-2 positions of the benzene ring were determined by NMR assays (delta1 and delta2). This value is related to the nucleophilic power of the oxygen atom of the hydroxyl groups and to its oxidation-reduction capacity. The spatial orientation of the ring substituents resulted in lower Km values for L- than for D-isomers. The kcat values for substrates capable of saturating the enzyme were lower for D- than for L-isomers, although both have the same delta1 and delta2 NMR values for carbons C-1 and C-2, and therefore the same oxidation-reduction potential. In the case of substrates that cannot saturate the enzyme, the values of the binding constant for compound II (an intermediate in the catalytic cycle) followed the order: L-isomer>DL-isomer>D-isomer. Therefore, horseradish peroxidase showed stereospecificity in its affinity toward its substrates (K m) and in their transformation reaction rates (k cat).

Algorithms↗
PubMed2001

[Autotrophic denitrification of groundwater by electrochemical process].

An autotrophic denitrification process and its reactor for removing nitrate from groundwater was investigated in this paper. Using activated carbon fiber(ACF) as electrodes, the electrochemical reactions could produce hydrogen as the donor for autotrophic denitrification. In the process, nitrate was removed effectively and no accumulation of nitrite in the effluent. The results in this study proved that some key factors, such as the applied current density, flow rate of water, oxidation-reduction potential and the nitrate concentration in raw water, influenced the electrochemically denitrifying effect. When the concentration of NO3(-)-N was 28.8 mg/L in inlet water, the optimum applied density was 9 mA, the highest hydraulic load of the reactor was 35 ml/h, and the reactor performed a practical buffering capacity to pH. After applying electricity to the reactor for 1 h, the oxidation-reduction potential decreased to below--200 mA, so an adaptable reductive environment could be provided in the reactor for denitrification.

Carbon↗
PubMed2006

Dynamics of ion exchange between self-assembled redox polyelectrolyte multilayer modified electrode and liquid electrolyte.

A probe beam deflection (PBD) study of ion exchange between an electroactive polymer poly(allylamine)-bipyridyl-pyridine osmium complex film and liquid electrolyte is reported. The PBD measurements were made simultaneously to chronoamperometric oxidation-reduction cycles, to be able to detect kinetic effects in the ion exchange. Layer-by-layer (LbL) self-assembled redox polyelectrolyte films with osmium bipyridyl complex covalently attached to poly(allylamine) (PAH-Os) and poly(styrene sulfonate) (PSS) have been built by alternate electrostatic adsorption from soluble polyelectrolytes. The ionic exchange during initial conditioning of the film ("break-in") undergoing oxidation-reduction cycles and recovery after equilibration in the reduced state have shown an exchange of anions and cations with time lag between them. The effect of the nature of cation on the ionic exchange has been investigated with dilute HCl, LiCl, NaCl, and CsCl electrolytes. The ratio of anion to cation exchanged at the film-electrolyte interface has a strong dependence on the nature of charge in the topmost layer, that is, when negatively charged PSS is the capping layer, a larger proportion of cation exchange is observed. This demonstrates that the electrical potential distribution at the redox polyelectrolyte multilayer (PEM)/electrolyte interface determines the ionic flux in response to charge injection in the film.

Journal Article↗
PubMed2001

Chronic alcohol consumption and cerebral indices of oxidative stress: is there a link?

BACKGROUND: It is still difficult to define the biochemical mechanisms that cause alterations in neuronal function and plasticity and neuronal cell loss in the brains of alcohol-dependent patients. METHODS: To evaluate the extent of cerebral alcohol-induced oxidative stress ex vivo, we investigated the levels of glutathione (GSH), its oxidation product glutathione disulfide (GSSG, produced by GSH-peroxidases), and the activities of catalase and superoxide dismutases (SOD). In addition, selected brain regions from up to 22 subjects (versus controls) were studied post mortem to compare the amount of oxidized DNA-base 8-hydroxy-2'-deoxyguanosine (8-OHdG) with levels of deoxyguanosine (dG) in mitochondrial and nuclear DNA. RESULTS: The most prominent findings showed significantly decreased GSH/(GSH+2GSSG) molar redox (oxidation-reduction) ratios in the corpus mamillare and cerebellum, which appeared due to an increase in GSSG caused by chronic alcohol intake. Catalase activity was increased in only the frontal cortex, whereas decreased catalase activity was found in the corpus callosum. In contrast, neither copper-zinc-superoxide dismutase (CuZnSOD) and manganese-superoxide dismutase (MnSOD) activities nor 8-OHdG/dG molar ratios were altered, although a tendency toward higher OHdG/dG ratios in temporal and parietal cortex from alcohol-dependent patients could be detected when mitochondrial DNA was analyzed selectively. CONCLUSIONS: We propose that decreased brain GSH/(GSH+2GSSG) molar redox (oxidation-reduction) ratios in alcohol-dependent patients may reflect neural impairment due to increased peroxide production after chronic alcohol consumption. However, future experiments, investigating the activities of enzymes and cofactors involved in GSH synthesis and metabolism in the human brain, will have to validate the specificity of these results for oxidative stress.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2004

Protein disulfide bond formation in the cytoplasm during oxidative stress.

The majority of disulfide-linked cytosolic proteins are thought to be enzymes that transiently form disulfide bonds while catalyzing oxidation-reduction (redox) processes. Recent evidence indicates that reactive oxygen species can act as signaling molecules by promoting the formation of disulfide bonds within or between select redox-sensitive proteins. However, few studies have attempted to examine global changes in disulfide bond formation following reactive oxygen species exposure. Here we isolate and identify disulfide-bonded proteins (DSBP) in a mammalian neuronal cell line (HT22) exposed to various oxidative insults by sequential nonreducing/reducing two-dimensional SDS-PAGE combined with mass spectrometry. By using this strategy, several known cytosolic DSBP, such as peroxiredoxins, thioredoxin reductase, nucleoside-diphosphate kinase, and ribonucleotide-diphosphate reductase, were identified. Unexpectedly, a large number of previously unknown DSBP were also found, including those involved in molecular chaperoning, translation, glycolysis, cytoskeletal structure, cell growth, and signal transduction. Treatment of cells with a wide range of hydrogen peroxide concentrations either promoted or inhibited disulfide bonding of select DSBP in a concentration-dependent manner. Decreasing the ratio of reduced to oxidized glutathione also promoted select disulfide bond formation within proteins from cytoplasmic extracts. In addition, an epitope-tagged version of the molecular chaperone HSP70 forms mixed disulfides with both beta4-spectrin and adenomatous polyposis coli protein in the cytosol. Our findings indicate that disulfide bond formation within families of cytoplasmic proteins is dependent on the nature of the oxidative insult and may provide a common mechanism used to control multiple physiological processes.

Adenomatous Polyposis Coli Protein↗
PubMed2004

Investigating mitochondrial redox potential with redox-sensitive green fluorescent protein indicators.

Current methods for determining ambient redox potential in cells are labor-intensive and generally require destruction of tissue. This precludes single cell or real time studies of changes in redox poise that result from metabolic processes or environmental influences. By substitution of surface-exposed residues on the Aequorea victoria green fluorescent protein (GFP) with cysteines in appropriate positions to form disulfide bonds, reduction-oxidation-sensitive GFPs (roGFPs) have been created. roGFPs have two fluorescence excitation maxima at about 400 and 490 nm and display rapid and reversible ratiometric changes in fluorescence in response to changes in ambient redox potential in vitro and in vivo. Crystal structure analyses of reduced and oxidized crystals of roGFP2 at 2.0- and 1.9-A resolution, respectively, reveal in the oxidized state a highly strained disulfide and localized main chain structural changes that presumably account for the state-dependent spectral changes. roGFP1 has been targeted to the mitochondria in HeLa cells. Fluorometric measurements on these cells using a fluorescence microscope or in cell suspension using a fluorometer reveal that the roGFP1 probe is in dynamic equilibrium with the mitochondrial redox status and responds to membrane-permeable reductants and oxidants. The roGFP1 probe reports that the matrix space in HeLa cell mitochondria is highly reducing, with a midpoint potential near -360 mV (assuming mitochondrial pH approximately 8.0 at 37 degrees C). In other work (C. T. Dooley, T. M. Dore, G. Hanson, W. C. Jackson, S. J. Remington, and R. Y. Tsien, submitted for publication), it is shown that the cytosol of HeLa cells is also unusually reducing but somewhat less so than the mitochondrial matrix.

Cell Line↗
PubMed2004

Catalysis of disulphide bond formation in the endoplasmic reticulum.

Disulphide bonds are critical for the maturation and stability of secretory and cell-surface proteins. In eukaryotic cells, disulphide bonds are introduced in the ER (endoplasmic reticulum), where the redox conditions are optimal to support their formation. Yet, the correct pairing of cysteine residues is not simple and often requires the assistance of redox-active proteins. The enzymes of the thiol-disulphide oxidoreductase family catalyse oxidation, reduction and isomerization, and thereby play important roles for the folding of many proteins. To allow all three redox reactions to take place concurrently in the same compartment, specific protein-protein interactions regulate the function of individual enzymes, while a careful balance of the ER redox environment is maintained. At the same time, the system must be capable of responding to changes in the cellular conditions, caused, for instance, by oxidative stress and protein misfolding. This review presents recent progress in understanding how ER redox conditions are regulated and how protein disulphides are formed in the ER of mammalian cells.

Animals↗
PubMed1991

[The use of antioxidants in treating patients with vibration-induced disease].

Current vibration disease prevalence and its health and national economy-revealed consequences necessitates further elaboration of pathogenesis-based techniques for the disease' treatment. Antioxidants, vitamin E in particular, were used to stabilize the cellular membrane's oxidation-reduction processes. The alpha-tocopherol membrane localization taken into account, the researchers hold that it is capable of protecting the biologic membranes from the damaging influence of fat acids by means of formation of the alpha-tocopherol and fat acids complexes. The treatment resulted into health-state improvement, normalization of the local processes in the upper extremities, which can be explained by the stabilization of the cellular membrane's oxidation-reduction, primarily due to vitamin E, thus proving its positive therapeutic effect.

Adult↗
PubMed1977

Enzymatic activity of blood lymphocytes experimental tsutsugamushi fever in mice.

The influence of tsutsugamushi fever infection on the metabolism of blood lymphocytes of mice differing in susceptibility to Rickettsia tsutsugamushi and of rifampicine and tetracycline treatment was studied. In susceptible mice, the activity of oxidation-reduction processes in lymphocytes increased at 7--10 days of the disease and became normal upon recovery of the animals. In mice with low susceptibility this increase of the activity began and terminated much earlier, at 3--5 days. Treatment of the infection with antibiotics resulted in a rapid arrest of the disease and normalization of the lymphocyte activity. The relationship between susceptibility of the animals to R. tsutsugamushi and the activity of oxidation-reduction enzymes is discussed on the example of succinate dehydrogenase.

Animals↗
PubMed1954

An enzymatic locus participating in cellular division of a yeast.

Growing cells of a filamentous mutant of a yeast, Candida albicans, were found to accumulate and reduce tetrazolium dyes whereas cells of the parent strain, growing as a normally budding yeast, accumulated the dye but did not reduce it. In older cultures, in which rapidly metabolizable carbohydrate has been depleted, the parent strain characteristically produces filaments. These cells, growing in the absence of cellular division, also exhibit tetrazolium reduction. The filamentous mutant synthesizes cell mass at a rate almost equal to that of the parent strain and is not distinguished therefrom in fermentation ability, nutritional requirements for growth, rate of endogenous respiration, or polysaccharide composition. These facts, in conjunction with the striking differences in tetrazolium reduction, lead to the conclusion that the morphological mutant has an impairment to a cellular oxidation mechanism at a flavoprotein locus. This locus is, then, the site at which a reaction essential for cellular division, is coupled via an oxidation-reduction to cellular metabolism. Preliminary evidence is presented providing good indication that uncoupling of cellular division (by genetic block) in the mutant or in the parent (by substrate exhaustion) results from impairment to a dissociable metal chelate mechanism which normally couples a reaction essential to cellular division to flavoprotein oxidation.

Candida↗
PubMed2001

Analysis and interpretation of the action mechanism of mushroom tyrosinase on monophenols and diphenols generating highly unstable o-quinones.

Tyrosinase can act on monophenols because of the mixture of met- (E(m)) and oxy-tyrosinase (E(ox)) which exists in the native form of the enzyme. The latter form is active on monophenols, while the former is not. However, the kinetics are complicated because monophenols can bind to both enzyme forms. This situation becomes even more complex since the products of the enzymatic reaction, the o-quinones, are unstable and continue evolving to generate o-diphenols in the medium. In the case of substrates such as L-tyrosine, tyrosinase generates very unstable o-quinones, in which a process of cyclation and subsequent oxidation-reduction generates o-diphenol through non-enzymatic reactions. However, the release of o-diphenol through the action of the enzyme on the monophenol contributes to the concentration of o-diphenol in the first pseudo-steady-state [D(0)](ss). Hence, the system reaches an initial pseudo-steady state when t-->0 and undergoes a transition phase (lag period) until a final steady state is reached when the concentration of o-diphenol in the medium reaches the concentration of the final steady state [D(f)](ss). These results can be explained by taking into account the kinetic and structural mechanism of the enzyme. In this, tyrosinase hydroxylates the monophenols to o-diphenols, generating an intermediate, E(m)D, which may oxidise the o-diphenol or release it directly to the medium. We surmise that the intermediate generated during the action of E(ox) on monophenols, E(m)D, has axial and equatorial bonds between the o-diphenol and copper atoms of the active site. Since the orbitals are not coplanar, the concerted oxidation-reduction reaction cannot occur. Instead, a bond, probably that of C-4, is broken to achieve coplanarity, producing a more labile intermediate that will then release the o-diphenol to the medium or reunite it diaxially, involving oxidation to o-quinone. The non-enzymatic evolution of the o-quinone would generate the o-diphenol ([D(f)](ss)) necessary for the final steady state to be reached after the lag period.

Agaricales↗
PubMed1978

Factors involved in colonization of the gut epithelial surface.

Some indigenous microbes form climax communities on gastrointestinal epithelial surfaces during succession in animals of many types. Most communities form in mucous layers on the surfaces, where some microbes in the communities may utilize the mucin as a source of carbon and energy. The mucous gel may also serve physically to stabilize the community. Some microbial types that colonize early during succession may serve, perhaps synergistically with dietary components, to lower the oxygen tension and oxidation-reduction potential so that oxygen-intolerant anaerobes can colonize the epithelial surfaces. Microbes in the communities may adhere to the epithelial surface; the mechanisms by which they adhere may depend upon a variety of factors, including the type of epithelium and the rate of flow of lumenal contents in the areas. Dietary fiber may influence the composition of these communities by providing nutrients for the microbes or altering their environmental conditions including peristaltic rate, mucous concentration and composition, and oxygen tension and oxidation-reduction potential.

Animals↗