Showing papers on "Hydrogen peroxide published in 1980"

Oxygen metabolism and the toxic properties of phagocytes.

Abstract: The products of oxygen reduction (superoxide anion, hydrogen peroxide, hydroxyl radicals) and excitation (singlet oxygen) have been implicated in the toxic properties of phagocytes (neutrophils, eosinophils, and mononuclear phagocytes). Enzymes that potentiate (such as peroxidase) or limit (such as catalase, superoxide dismutase) the toxicity of these agents contribute to the complexity of the oxygen-dependent antimicrobial systems of phagocytes. These toxic systems are dormant when the phagocyte is at rest but are activated when the need arises and directed to the destruction of invading microorganisms and other foreign cells. Occasionally, the toxic systems are directed against normal host cells and in this way contribute to the pathogenesis of disease.

Spectrophotometric determination of hydrogen peroxide using potassium titanium(IV) oxalate

Abstract: A simple and rapid method for the spectrophotometric determination of hydrogen peroxide using potassium titanium(IV) oxalate is described. The method can be used to measure peroxide concentrations down to about 10 µM(0.3 mg kg–1) under the most favourable conditions. A variety of complexing and reducing agents, and catalysts of peroxide decomposition, known to interfere with the alternative iodide method for peroxide determination, had no effect. Fluoride was found to interfere.

Adsorption as a control of metal concentrations in sediment extracts.

Abstract: w The adsorption of Cu, Pb, and Cd from selected extractant solutions, onto uncontaminated river sediments, has been investigated under typical extraction conditions. Significant adsqrption of added metal was found to occur during overnight extraction with dilute HC1 (pH >1.5), 0.1 M hydroxylamine hydrochloride (pH 2), 0.1 M sodium citrate (pH 4.6), 1 M ammonium acetate, 10% sodium citrate-1% sodium dithionite, and 25% acetic acid. Adsorption also occurred during a hydrogen peroxide digestion procedure. The inability of reagents to prevent losses of soluble metal in these experiments strongly suggests that a proportion of the metal actually released from a sediment sample during an extraction will be readsorbed. This may lead to serious misinterpretation of extraction data because the metal concentrations determined in the extract do not represent metal levels in the sediment fractions attacked.

Role of oxygen-dependent mechanisms in antibody-induced lysis of tumor cells by activated macrophages*

Abstract: The alloantiserum-dependent lysis of TLX9 lymphoma cells by peritoneal cells from Bacille Calmette-Guerin (BCG)-treated mice was inhibited 62 percent by depletion of oxygen. This effect did not appear to be a result of interference with mitochondrial respiration because cyanide, azide, and dinitrophenol did not inhibit cytotoxicity. Preincubating the effector cells for 2 h without glucose, which markedly reduces their ability to release hydrogen peroxide, likewise suppressed antibody-dependent cytolysis by 62 percent. Lysis of sensitized lymphoma cells was virtually abolished by 6 mg/ml of thioglycollate broth, a concentration that also abrogated the detectable release of hydrogen peroxide and the lysis of lymphoma cells by BCG-activated macrophages in response to phorbol myristate acetate (PMA). This concentration of thioglycollate broth was not toxic to the effector cells, as judged by adherence to plastic, binding of opsonized erythrocytes, and phagocytosis of radiolabeled starch granules. Catalase, superoxide dismutase, horseradish peroxidase, mannitol, ethanol, benzoate, and diazabicyclooctane were without consistent effects. Cytochalasin B and dihydrocytochalasin B both markedly suppressed cytolysis, whether induced by antibody or by PMA (ID(50), 0.5 μg/ml). Cytoehalasin B was an equally potent suppressor of glucose uptake and PMA-induced hydrogen peroxide release by BCG-activated macrophages (ID(50), 0.5 μg/ml). However, dihydrocytochalasin B lacked these latter effects, which suggests that cytotoxicity required intact contractile elements. The extracellular lysis of antibody-coated lymphoma cells by BCG-activated macrophages appears to have a predominantly oxidative basis.

Inhibition of alloxan action in isolated pancreatic islets by superoxide dismutase, catalase, and a metal chelator.

Abstract: The possible participation of superoxide anions, hydrogen peroxide, and hydroxyl radicals in the action of alloxan was investigated using isolated rat pancreatic islets. Exposure of islets for 5 min to alloxan (0.15 or 0.2 mg/ml) inhibited subsequent glucose-stimulated insulin release. The presence of superoxide dismutase (1000 U/ml), catalase (50 μg/ml), or a metal chelator diethylenetriaminepentacetic acid (1 mM) markedly attenuated this effect of alloxan. Use of these agents afforded complete protection from the lower concentration of alloxan and partial protection from the higher concentration of the toxic compound. Inactivation of the enzymes or addition of excess iron to the chelating agent before its use with alloxan eliminated the protective action of these agents. The results are consistent with the proposal that hydroxyl radicals, generated via reactions that involve superoxide anions, hydrogen peroxide, and iron, mediate the deleterious effect of alloxan in pancreaticislets.

Damage to Candida albicans Hyphae and Pseudohyphae by the Myeloperoxidase System and Oxidative Products of Neutrophil Metabolism In Vitro

Abstract: In previous studies, we noted that Candida hyphae and pseudohyphae could be damaged and probably killed by neutrophils, primarily by oxygen-dependent nonphagocytic mechanisms. In extending these studies, amount of damage to hyphae again was measured by inhibition of [(14)C]cytosine uptake. Neutrophils from only one of four patients with chronic granulomatous disease damaged hyphae at all, and neutrophils from this single patient damaged hyphae far less efficiently than simultaneously tested neutrophils from normal control subjects. Neutrophils from neither of two subjects with hereditary myeloperoxidase deficiency damaged the hyphae. This confirmed the importance of oxidative mechanisms in general and myeloperoxidase-mediated systems in particular in damaging Candida hyphae. Several potentially fungicidal oxidative intermediates are produced by metabolic pathways of normal neutrophils, but their relative toxicity for Candida hyphae was previously unknown. To help determine this, cell-free in vitro systems were used to generate these potentially microbicidal products. Myeloperoxidase with hydrogen peroxide, iodide, and chloride resulted in 91.2% damage to hyphal inocula in 11 experiments. There was less damage when either chloride or iodide was omitted, and no damage when myeloperoxidase was omitted or inactivated by heating. Azide, cyanide, and catalase (but not heated catalase) inhibited the damage. Systems for generation of hydrogen peroxide could replace reagent hydrogen peroxide in the myeloperoxidase system. These included glucose oxidase, in the presence of glucose, and xanthine oxidase, in the presence of either hypoxanthine or acetaldehyde. In the presence of myeloperoxidase and a halide, the toxicity of the xanthine oxidase system was not inhibited by superoxide dismutase and, under some conditions, was marginally increased by this enzyme. This suggested that superoxide radical did not damage hyphae directly but served primarily as an intermediate in the production of hydrogen peroxide. The possible damage to hyphae by singlet oxygen was examined using photoactivation of rose bengal. This dye damaged hyphae in the presence of light and oxygen. The effect was almost completely inhibited by putative quenchers of singlet oxygen: histidine, tryptophan, and 1,4-diazobicyclo[2.2.2]octane. These agents also inhibited damage to hyphae by myeloperoxidase, halide, and either hydrogen peroxide or a peroxide source (xanthine oxidase plus acetaldehyde). Myeloperoxidase-mediated damage to hyphae was also inhibited by dimethyl sulfoxide, an antioxidant and scavenger of the hydroxyl radical. These data support the involvement of oxidative mechanisms and the myeloperoxidase-H(2)O(2)-halide system, in particular in damaging hyphae in vitro and perhaps in vivo as well.

Metabolism of hydrogen peroxide in Euglena gracilis Z by L-ascorbic acid peroxidase.

Abstract: Euglena gracilis was found to contain a peroxidase that specifically require L-ascorbic acid as the natural electron donor in the cytosol. The presence of an oxidation-reduction system metabolizing L-ascorbic acid was demonstrated in Euglena cells. Oxidation of L-ascorbic acid by the peroxidase, and the absence of ascorbic acid oxidase activity, suggests that the system functions to remove H2O2 in E. gracilis, which lacks catalase.

Degradation of deoxyribonucleic acid by a 1,10-phenanthroline-copper complex: the role of hydroxyl radicals.

Abstract: Degradation of deoxyribonucleic acid (DNA) by 1,10-phenanthroline has been shown to require Cu(II), a reducing agent, and O2. Other metal ions do not substitute for Cu(II), and degradation of DNA is inhibited by metal ions that can form stable complexes with 1,10-phenanthroline, such as Co(II), Cd(II), Ni(II), or Zn(II), as well as by chelators that can bind copper, such as triethyltetraamine, neocuproine, or ethylenediaminetetraacetic acid (EDTA). Neocuproine, a specific copper chelator, is more effective than EDTA in inhibiting the breakdown of DNA. The degradation of DNA shows a requirement for a reducing agent which can be satisfied by either ascorbate or a thiol. A free radical generating system, e.g., xanthine oxidase-hypoxanthine, can substitute for the reducing agent. DNA degradation, in the presence of either an organic reducing agent or xanthine oxidase-hypoxanthine, is inhibited by hydroxyl radical scavengers and by catalase, suggesting that hydroxyl radical is the reactive species in DNA degradation and that hydrogen peroxide is an intermediate in hydroxyl radical generation.

The recA+ gene product is more important than catalase and superoxide dismutase in protecting Escherichia coli against hydrogen peroxide toxicity.

Abstract: Various deoxyribonucleic acid repair-deficient strains of Escherichia coli K-12 were exposed to hydrogen peroxide under anaerobic conling of the strains was determined. The level of catalase, peroxidase, and superoxide dismutase in cell-free extracts of the strains as well as the capacity of intact cells to decompose hydrogen peroxide were assayed, recA strains were more rapidly killed than other strains with deoxyribonucleic acid repair deficiencies. There was no correlation between the killing rate of the strains and the capacity of intact cells to decompose hydrogen peroxide or the level of catalase and superoxide dismutase in cell-free extracts. The level of peroxidase in cell-free extract was too low to be determined.

Spectrophotometric determination of urinary oxalate with oxalate oxidase prepared from moss.

Abstract: A novel spectrophotometric enzymic procedure for estimating oxalic acid in urine is described. Oxalate oxidase, prepared from moss species, converts oxalic acid to hydrogen peroxide and carbon dioxide. Hydrogen peroxide is determined enzymatically with horseradish peroxidase, by oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone with N,N-dimethylaniline; the resulting indamine due is determined spectrophotometrically at 595 nm. Interfering substances are removed by adsorption to ion-exchange resins and oxidation with charcoal, thus avoiding oxalate recovery problems accompanying oxalate isolation. The procedure is rapid, sensitive, linear, and precise. Results agreed well with those obtained with a widely used chemical technique.

Induction and Characterization of a Cellobiose Dehydrogenase Produced by a Species of Monilia

Abstract: Summary: A species of the imperfect fungus Monilia produced cellobiose dehydrogenase extracellularly when grown on cellulose. The inducible enzyme was both bound to the mycelium and released into the growth medium. The enzyme showed a high degree of specificity for cellobiose, but also oxidized lactose and 4-β-glucosylmannose. The specificity of the electron acceptor was restricted to those compounds having a redox potential of +0.22 V. ρ-Benzoquinone and several other quinones, however, were not reduced. Oxygen was not consumed nor was hydrogen peroxide produced by cellobiose dehydrogenase oxidation of cellobiose. The enzyme had a molecular weight of 48000 and an isoelectric point of 5.3 to 5.5. A new zymogram technique was developed for the detection of cellobiose dehydrogenase in polyacrylamide gels following electrophoresis and isoelectric focusing.

Method for determination of hydrogen peroxide, with its application illustrated by glucose assay.

Abstract: We describe a simple colorimetric method for determining micromolar quantities of hydrogen peroxide, based on the oxidation of iodide in the presence of ammonium molybdate and photometry of the resulting blue starch-iodine complex. Color development is linearly dependent on analyte concentration, but only slightly time dependent, and the color of the complex formed is stable for several hours. In the range of wavelengths that may be used (570 to 630 nm), lack of interference from other biological compounds makes this method seem suitable for routine analyses. As one illustrative application of the method we quantitated glucose by measuring hydrogen peroxide produced from it by glucose oxidase catalysis. This method of quantitating glucose is more than five times as sensitive as the commonly used dianisidine method. With the appropriate hydrogen peroxide-producing oxidases, this method may be used to directly measure amino acids, purines, uric acid, xanthine, and hypoxanthine.

Improvements in methods of sterilization

Abstract: A method of sterilization which comprises treating a microorganism with an ultraviolet irradiated solution of hydrogen peroxide, the wavelength of the ultraviolet radiation being wholly or predominantly below 325 nm and the concentration of the hydrogen peroxide being no greater than 10% by weight and such that the microorganism is rendered non-viable by synergism between the radiation and the hydrogen peroxide. The invention is particularly applicable to the treatment of spores contaminating food packaging.

Antiinflammatory effects of free radical scavengers and antioxidants: further support for proinflammatory roles of endogenous hydrogen peroxide and lipid peroxides.

Abstract: Scavengers of reactive oxygen species were tested by local administration during granulomatous inflammation in the rat, induced by the subdermal implantation of carrageenin-soaked sponges. Drugs were administered either in a single dose immediately after sponge implantation, or in daily doses on days 3–6 of inflammation. The effects of the injected drugs were assessed using the day 7 granuloma. When given at the moment of sponge implantation, catalase showed antiinflammatory effects, whereas Superoxide dismutase did not. However, the addition of Superoxide dismutase to catalase, prior to injection, markedly potentiated the inhibition of granuloma formation by catalase alone. Negative results obtained with scavengers of hydroxyl radicals and singlet molecular oxygen suggest that protection of superoxide dismutase by catalase from inactivation by hydrogen peroxide, is a likely explanation for the observed potentiation. When administered at the moment of the induction of inflammation,α-tocopherol and propyl gallate, both antioxidants, also inhibited granuloma formation. All drugs tested were either ineffective or even enhanced granuloma weight following administration into a preformed granuloma. An inhibitor of both pathways of arachidonate metabolism, phenidone, inhibited granuloma formation irrespective of the moment of administration. The results presented in this paper suggest proinflammatory roles for hydrogen peroxide and lipid peroxides and a possible involvement of hydroxyl radicals and singlet oxygen in the breakdown of collagen.