Protection from superoxide damage associated with an increased level of the YggX protein in Salmonella enterica

The deleterious effect of superoxide radicals on cell growth and survival is predominately caused by rapid oxidation of labile [Fe-S] clusters in proteins. Oxidation of these clusters releases Fe(II) ions, which participate in Fenton chemistry that damages DNA. Here it is shown that elevated levels of the YggX protein increase the resistance of Salmonella enterica to superoxide stress, reverse enzymatic defects attributed to oxidized [Fe-S] clusters, and decrease the spontaneous mutation frequency. The data are consistent with a model in which YggX protects protein [Fe-S] clusters from oxidation.

A comparison of oxidation ditch plants to competing processes for secondary and advanced treatment of municipal wastes /

Mode of access: Internet.

Oxidation ditch treatment of meatpacking wastes /

Jan. 1979.

Oxidation techniques in drinking water treatment : papers presented at the Conference held in Karlsruhe, Federal Republic of Germany, September 11-13, 1978 /

Mode of access: Internet.

Supercritical water oxidation.

Mode of access: Internet.

Ultrox International ultraviolet radiation/oxidation technology : applications analysis report.

Mode of access: Internet.

Chemical oxidation treatment.

Mode of access: Internet.

Oxidation of organic matter in sediments /

Prepared for Office of Research and Development, U.S. Environmental Protection Agency.

Functional expression and characterization of Eehinococcus granulosus thioredoxin peroxidase suggests a role in protection against oxidative damage

A full-length cDNA sequence coding for Echinococcus granulosus thioredoxin peroxidase (EgTPx) was isolated from a sheep strain protoscolex cDNA library by immunoscreening using a pool of sera from mice infected with oncospheres. EgTPx expressed as a fusion protein with glutathione S-transferase (GST) exhibited significant thiol-dependent peroxidase activity that protected plasmid DNA from damage by metal-catalyzed oxidation (MCO) in vitro. Furthermore, the suggested antioxidant role for EgTPx was reinforced in an in vivo assay, whereby its expression in BL21 bacterial cells markedly increased the tolerance and survival of the cells to high concentrations of H2O2 compared with controls. Immunolocalization studies revealed that EgTPx was specifically expressed in all tissues of the protoscolex and brood capsules. Higher intensity of labelling was detected in many, but not all, calcareous corpuscle cells in protoscoleces. The purified recombinant EgTPx protein was used to screen sera from heavily infected mice and patients with confirmed hydatid infection. Only a portion of the sera reacted positively with the EgTPx-GST fusion protein in Western blots, suggesting that EgTPx may form antibody-antigen complexes or that responses to the EgTPx antigen may be immunologically regulated. Recombinant EgTPx may prove useful for the screening of specific inhibitors that could serve as new drugs for treatment of hydatid disease. Moreover, given that TPx from different parasitic phyla were phylogenetically distant from host TPx molecules, the development of antiparasite TPx inhibitors that do not react with host TPx might be feasible. (C) 2003 Elsevier B.V. All rights reserved.

Polyunsaturated fatty acid oxidation in Alzheimer’s disease.

Alzheimer’s disease is a neurodegenerative disorder which has been characterised with genetic (apolipoproteins), protein (ß-amyloid and tau) and lipid oxidation/metabolism alterations in its pathogenesis. In conjunction with the Dementia Research Group, Bristol University, investigation into genetic, protein and lipid oxidation in Alzheimer’s disease was conducted. A large sample cohort using the double-blind criteria, along with various clinical and chemical data sets were used to improve the statistical analysis and therefore the strength of this particular study. Bristol University completed genetic and protein analysis with lipid oxidation assays performed at Aston University. Lipid oxidation is a complex process that creates various biomarkers, from transient intermediates, to short carbon chain products and cyclic ring structures. Quantification of these products was performed on lipid extracts of donated clinical diseased and non-diseased frontal and temporal brain regions, from the Brain Bank within Frenchay Hospital. The initial unoxidised fatty acids, first transient oxidation intermediates the conjugated dienes and lipid hydroperoxides, the endpoint aldehyde biomarkers and finally the cyclic isoprostanes and neuroprostanes were determined to investigate lipid oxidation in Alzheimer’s. Antioxidant levels were also investigated to observe the effect of oxidation on the defence pathways. Assays utilised in this analysis included; fatty acid composition by GC-FID, conjugated diene levels by HPLC-UV and UV-spec, lipid hydroperoxide levels by FOX, aldehyde content by TBARs, antioxidant status by TEAC and finally isoprostane and neuroprostane quantification using a newly developed EI-MS method. This method involved the SIM of specific ions from F-ring isoprostane and neuroprostane fragmentation, which enabled EI-MS to be used for their quantification. Analyses demonstrated that there was no significant difference between control and Alzheimer samples across all the oxidation biomarkers for both brain regions. Antioxidants were the only marker that showed a clear variance; with Alzheimer samples having higher levels than the age matched controls. This unique finding is supported with the observed lower levels of lipid oxidation biomarkers in Alzheimer brain region samples. The increased antioxidant levels indicate protection against oxidation which may be a host response to counteract the oxidative pathways, but this requires further investigation. In terms of lipid oxidation, no definitive markers or target site for therapeutic intervention have been revealed. This study concludes that dietary supplementation of omega-3 fatty acids or antioxidants would most likely be ineffective against Alzheimer disease, although it may support improvement in other areas of general health.

Antioxidants and protein oxidation

Proteins are susceptible to oxidation by reactive oxygen species, where the type of damage induced is characteristic of the denaturing species. The induction of protein carbonyls is a widely applied biomarker, arising from primary oxidative insult. However, when applied to complex biological and pathological conditions it can be subject to interference from lipid, carbohydrate and DNA oxidation products. More recently, interest has focused on the analysis of specific protein bound oxidised amino acids. Of the 22 amino acids, aromatic and sulphydryl containing residues have been regarded as being particularly susceptible to oxidative modification, with L-DOPA from tyrosine, ortho-tyrosine from phenylalanine; sulphoxides and disulphides from methionine and cysteine respectively; and kynurenines from tryptophan. Latterly, the identification of valine and leucine hydroxides, reduced from hydroperoxide intermediates, has been described and applied. In order to examine the nature of oxidative damage and protective efficacy of antioxidants the markers must be thoroughly evaluated for dosimetry in vitro following damage by specific radical species. Antioxidant protection against formation of the biomarker should be demonstrated in vitro. Quantification of biomarkers in proteins from normal subjects should be within the limits of detection of any analytical procedure. Further to this, the techniques for isolation and hydrolysis of specific proteins should demonstrate that in vitro oxidation is minimised. There is a need for the development of standards for quality assurance material to standardise procedures between laboratories. At present, antioxidant effects on protein oxidation in vivo are limited to animal studies, where dietary antioxidants have been reported to reduce dityrosine formation during rat exercise training. Two studies on humans have been reported last year. The further application of these methods to human studies is indicated, where the quality of the determinations will be enhanced through inter-laboratory validation.

Cathodic protection of reinforced concrete:anodic processes in cements and related electrolytes

The nature and kinetics of electrode reactions and processes occurring for four lightweight anode systems which have been utilised in reinforced concrete cathodic protection systems have been studied. The anodes investigated were flame sprayed zinc, conductive paint and two activated titanium meshes. The electrochemical properties of each material were investigated in rapidly stirred de-oxygenated electrolytes using anodic potentiodynamic polarisation. Conductive coating electrodes were formed on glass microscope slides, whilst mesh strands were immersed directly. Oxygen evolution occurred preferentially for both mesh anodes in saturated Ca (OH)2/CaC12 solutions but was severely inhibited in less alkaline solutions and significant current only passed in chloride solutions. The main reactions for conductive paint was based on oxygen evolution in all electrolytes, although chlorides increased the electrical activity. Self-corrosion of zinc was controlled by electrolyte composition and the experimental set-up, chlorides increasing the electrical activity. Impressed current cathodic protection was applied to 25 externally exposed concrete slabs over a period of 18 months to investigate anode degradation mechanisms at normal and high current densities. Specimen chloride content, curing and reinforcement depth were also variables. Several destructive and non-destructive methods for assessing the performance of anodes were evaluated including a site instrument for quantitative "instant-off- potential measurements. The impact of cathodic protection on the concrete substrate was determined for a number of specimens using appropriate methods. Anodic degradation rates were primarily influenced by current density, followed by cemendtious alkalinity, chloride levels and by current distribution. Degradation of cementitious overlays and conductive paint substrates proceeded by sequential neutralisation of cement phases, with some evidence of paint binder oxidation. Sprayed zinc progressively formed an insulating layer of hydroxide complexes, which underwent pitting_ attack in the presence of sufficient chlorides, whilst substrate degradation was minimal. Adhesion of all anode systems decreased with increasing current density. The influence of anode material on the ionic gradients which can develop during cathodic protection was investigated. A constant current was passed through saturated cement paste prisms containing calcium chloride to central cathodes via anodes applied or embedded at each end. Pore solution was obtained from successive cut paste slices for anion and cation analyses. Various experimental errors reduced the value of the results. Characteristic S-shaped profiles were not observed and chloride ion profiles were ambiguous. Mesh anode specimens were significantly more durable than the conductive coatings in the high humidity environment. Limited results suggested zinc ion migration to the cathode region. Electrical data from each investigation clearly indicated a decreasing order of anode efficiency by specific anode material.

Protection of human erythrocytes against oxidative stress by berries

Berries contain several bioactive compounds that can protect against oxidative stress. In this study we evaluated the protective effect of different sequential extracts (ethyl acetate, ethanol and water) of seven berry species: bilberry (Vaccinium myrtillus), blackcurrant (Ribes nigrum), elderberry (Sambucus nigra), lingonberry (Vaccinium vitis-idaea), rose hips (Rosa sp.), sea buckthorn (Hippohae rhamnoides) and strawberry (Fragaria × ananassa). The protective effect was tested on human erythrocytes and the antioxidant capacity was also evaluated in vitro by the FRAP assay. In the erythrocyte assay all sea buckthorn extracts were superior in antioxidant effect to other berry extracts. The ethyl acetate extract of bilberries, and the ethanol and water extracts of blackcurrants, also protected the erythrocytes from oxidation. In contrast, water extracts of rose hips, bilberries and strawberries had a pro-oxidant effect on erythrocytes. The water extract of rose hips was superior to the other berry extracts in the FRAP assay. Thus, the results of the erythrocyte assay did not correlate with the results of the FRAP assay, but provided additional insights into the potential protective effects of berry extracts against oxidative stress. © 2012 - IOS Press and the authors. All rights reserved.

[health Protection For Rural Workers: The Need To Standardize Techniques For Quantifying Dermal Exposure To Pesticides].

Quantification of dermal exposure to pesticides in rural workers, used in risk assessment, can be performed with different techniques such as patches or whole body evaluation. However, the wide variety of methods can jeopardize the process by producing disparate results, depending on the principles in sample collection. A critical review was thus performed on the main techniques for quantifying dermal exposure, calling attention to this issue and the need to establish a single methodology for quantification of dermal exposure in rural workers. Such harmonization of different techniques should help achieve safer and healthier working conditions. Techniques that can provide reliable exposure data are an essential first step towards avoiding harm to workers' health.