External Hydrogen Peroxide Research Articles

Feedback of hypoxia-inducible factor-1alpha (HIF-1alpha) transcriptional activity via redox factor-1 (Ref-1) induction by reactive oxygen species (ROS)

Hypoxia-inducible factor-1alpha (HIF-1alpha) is important for adaptation to hypoxia. Hypoxia is a common feature of cancer and inflammation, by which HIF-1alpha increases. However, prolonged hypoxia decreases HIF-1alpha, and the underlying mechanisms currently remain unclear. Cellular reactive oxygen species (ROS) increases in cancer and inflammation. In the present study, we demonstrated that prolonged hypoxia increased ROS, which induced prolyl hydroxylase domain-containing protein 2 (PHD2) and factor inhibiting HIF-1 (FIH-1), major regulators of HIF-1alpha. Cellular stress response (CSR) increased HIF-1alpha transcriptional activity by scavenging endogenous ROS. PHD2 and FIH-1 were induced by external hydrogen peroxide (H2O2) but were suppressed by ROS-scavenging catalase. We investigated the mechanisms by which PHD2 and FIH-1 are regulated by ROS. The knockdown of HIF-1alpha decreased PHD2 and FIH-1 mRNA levels, suggesting their regulation by HIF-1alpha. We then focused on redox factor-1 (Ref-1), which is a regulator of HIF-1alpha transcriptional activity. The knockdown of Ref-1 decreased PHD2 and FIH-1. Ref-1 was regulated by ROS. Prolonged hypoxia and the addition of H2O2 induced the expression of Ref-1. Furthermore, the knockdown of p65, a component of kappa-light-chain enhancer of activated B cells (NF-κB), efficiently inhibited the induction of Ref-1 by ROS. Collectively, the present results showed that prolonged hypoxia or increased ROS levels induced Ref-1, leading to the activation of HIF-1alpha transcriptional activity, while the activation of HIF-1alpha via Ref-1 induced PHD2 and FIH-1, causing the feedback of HIF-1alpha. To the best of our knowledge, this is the first study to demonstrate the regulation of HIF-1alpha via Ref-1 by ROS.

Preparation of Kissiris/TiO2/Fe3O4/GOx Biocatalyst: Feasibility study of MG decolorization

Titanium dioxide (TiO2) and Fe3O4 magnetite particles were coated on spherical Kissirises; glucose oxidase (GOx) enzyme was immobilized on Kissiris/Fe3O4/TiO2 by physical adsorption. This catalyst was analyzed by a scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray (EDX) measurements. The performance of the prepared biocatalyst in the decolorization of Malachite Green dye was investigated. The optimal operation parameters were 20 mg/L, 20 mM, 5.5 and 40 C for initial dye concentration, initial glucose concentration, pH and temperature, respectively. Under these conditions, a 95% Malachite Green decolorization efficiency was obtained after 150 min of reaction by using 1 g of prepared heterogeneous bio-Fenton catalyst. In this process, in contrast to a conventional Fenton’s reaction, external hydrogen peroxide and ferrous ion sources were not used. The effect of various reaction parameters such as initial concentration of dye, amount of catalyst, concentration of glucose, pH value and temperature on MG decolorization efficiency was studied.

Preparation of heterogeneous bio-Fenton catalyst for decolorization of Malachite Green

Titanium dioxide (TiO2) and Fe3O4 magnetite particles were coated on spherical Kissirises; and glucose oxidase (GOx) enzyme was immobilized on Kissiris/Fe3O4/TiO2 by physical adsorption. Performance of the prepared biocatalyst in decolorization of Malachite Green dye was investigated. Ninety-nine percent Malachite Green decolorization was obtained after 120 min by using 2 g of the heterogeneous bio-Fenton catalyst at initial dye concentration of 20 mg/L, initial glucose concentration of 20 mM, pH 5.5 and temperature of 40 °C. In this process, in contrast to conventional Fenton's reaction, external hydrogen peroxide and ferrous ion sources were not used.

Investigating Catalase Activity Through Hydrogen Peroxide Decomposition by Bacteria Biofilms in Real Time Using Scanning Electrochemical Microscopy

Catalase activity through hydrogen peroxide decomposition in a 1 mM bulk solution above Vibrio fischeri (γ-Protebacteria-Vibrionaceae) bacterial biofilms of either symbiotic or free-living strains was studied in real time by scanning electrochemical microscopy (SECM). The catalase activity, in units of micromoles hydrogen peroxide decomposed per minute over a period of 348 s, was found to vary with incubation time of each biofilm in correlation with the corresponding growth curve of bacteria in liquid culture. Average catalase activity for the same incubation times ranging from 1 to 12 h was found to be 0.28 ± 0.07 μmol H2O2/min for the symbiotic biofilms and 0.31 ± 0.07 μmol H2O2/min for the free-living biofilms, suggesting similar catalase activity. Calculations based on Comsol Multiphysics simulations in fitting experimental biofilm data indicated that approximately (3 ± 1) × 10(6) molecules of hydrogen peroxide were decomposed by a single bacterium per second, signifying the presence of a highly active catalase. A 2-fold enhancement in catalase activity was found for both free-living and symbiotic biofilms in response to external hydrogen peroxide concentrations as low as 1 nM in the growth media, implying a similar mechanism in responding to oxidative stress.

Hydrogen Peroxide Treatments Administered to Hatchery‐Reared Burbot: Assessing Treatment Regimes from Embryonic Development through Juvenile Rearing

AbstractBurbot Lota lota is an emerging aquaculture species, in which fungal infestations during early life stage development are common. In this study, the tolerance of Burbot to external hydrogen peroxide (H2O2) treatment regimes was examined during four early life stages to determine species and life stage‐specific sensitivity. Yolk‐sac larvae tolerated three 1‐h treatments up to 250 μL/L H2O2 without significant reduction in survival. Preflexion larvae tolerated only 100 μL/L H2O2 before survival was affected. In both cases, decreased survival was only observed after administration of three consecutive treatments. Flexion larvae tolerated up to 250 μL/L H2O2, but by the juvenile stage sensitivity again increased to 100 μL/L H2O2 before survival was affected. In these latter stages, decreased survival was observed immediately following the first H2O2 treatment, suggesting a mechanism for toxicity that is different than that in previous life stages. As has previously been shown, H2O2 can be effective for controlling aquatic bacteria and fungus at or below 250 μL/L, and our results indicate that H2O2 concentrations currently used during Burbot egg incubation may be extended into the larval rearing stage for effective fungal control without negatively affecting survival of either eggs or newly hatched larvae. Additionally, treatment regimes may be continued through juvenile development for the purpose of controlling external pathogens in the hatchery production of Burbot.

Differential response of gastric carcinoma MKN-45 and 23132/87 cells to H2O2 exposure

Reactive oxygen species are involved in tumor progression but how they function is not well understood. In this study, we investigated and compared the effects of hydrogen peroxide on the survival, apoptosis, accumulation of oxidative stress, and matrix metalloprotein-7 gene expression on human gastric carcinoma MKN-45 and 23132/87 cells. The cell lines were exposed to hydrogen peroxide in a dose- and time-dependent manner. The surviving cells were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The oxidative stress was analyzed by an oxidative stress marker, 2,7-dichlorofluorescein diacetate, under fluorescence microscope. The effect of oxidative stress on the apoptotic behavior, caspase-3 activity, and matrix metalloprotein-7 gene expressions of the cell lines were determined, respectively, by TUNEL, caspase-3 activity assay, and quantitative real-time polymerase chain reaction. Exposure of the gastric cancer cells to oxidative stress resulted in dose- and time-dependent decrease in the survival of the cell lines. While MKN-45 cells had oxidative stress, increased apoptosis with no caspase-3 activity, and increased matrix metalloprotein-7 expression following hydrogen peroxide exposure, 23132/87 cells showed none, with internal oxidative stress accumulation prior to hydrogen peroxide exposure. The two gastric cancer cell lines responded differently to oxidative stress conditions, and unlike in 23132/87 cells, matrix metalloprotein-7 gene expression was shown to be affected by external hydrogen peroxide in MKN-45 cells.

Chemiluminescence‐Generating Nanoreactor Formulation for Near‐Infrared Imaging of Hydrogen Peroxide and Glucose Level in vivo

AbstractWater‐dispersed all‐in‐one nanoprobes composed of densely integrated peroxyoxalate fuel and a cyanine dye are formulated to optimize the nanoscopic chemiluminescence reaction. It is demonstrated that the chemiluminescent nanoformulation can generate bright near‐infrared signal in response to external hydrogen peroxide that is biologically implicated with cell signaling and diseases. Successful imaging of endogenously overproduces hydrogen peroxide and indirect determination of glucose level in vivo with the chemiluminescent nanoprobes offers an opportunity for early diagnosis of diseases.

Chemiluminescence‐Generating Nanoreactor Formulation for Near‐Infrared Imaging of Hydrogen Peroxide and Glucose Level in vivo

AbstractWater‐dispersed all‐in‐one nanoprobes composed of densely integrated peroxyoxalate fuel and a cyanine dye are formulated to optimize the nanoscopic chemiluminescence reaction. It is demonstrated that the chemiluminescent nanoformulation can generate bright near‐infrared signal in response to external hydrogen peroxide that is biologically implicated with cell signaling and diseases. Successful imaging of endogenously overproduces hydrogen peroxide and indirect determination of glucose level in vivo with the chemiluminescent nanoprobes offers an opportunity for early diagnosis of diseases.

Thesis Abstract Gene expression and nutrient utilization in the basideomycete Moniliophthora perniciosa suggest the existence of regulatory mechanisms of catabolite repression

of Dissertation. Orienting Prof.: Dr. Cristina Pungartnik. Moniliophthora perniciosa, a hemibiotrophic fungus (characterized by biotrophic and saprotrophic phases in its life cycle), is the causal agent of witches’ broom disease (WBD), which negatively affects the Latin American cocoa (Theobroma cacao) production. The southern region of Bahia, in Brazil, had the first occurrence of WBD in 1989, which led to a great drop in cacao production in the following years. During the biotrophic phase, the infecting fungus promotes stem enlargement, hyperplasic and hypertrophic tissue growth, loss of apical dominance, and green broom formation in T. cacao. During the saprotrophic phase of fungal infection, the green broom turns into a dry one, due to an intense programmed cell death that leads to necrosis of infected parts of the plant. Studies have suggested the presence of a carbon repression (CR) mechanism in M. perniciosa. CR is well characterized in the yeast Saccharomyces cerevisiae and consists in the repression or induction of a set of genes according to the type of carbon source present in the environment. MIG1 and SNF1 genes encode transcription factors that are involved in the regulation of the CR process. The aim of this study was to demonstrate the existence of CR and to characterize its process in M. perniciosa through physiological studies and analysis of gene expression. The fungus was grown in media with different glucose and glycerol concentrations, and mycelial growth, carbon and peptone consumption profile of the culture medium, pH variation, and resistance to oxidative stress generated by external hydrogen peroxide (H2O2) were monitored. Real-time polymerase chain reaction (qPCR) was used for expression analysis of selected genes of CR, energy metabolism, autophagy, and protection against oxidative stress agents. The main results were: i) peptone seems to be important in fungal nutrition and growth, being preferentially consumed, even in the presence of glucose or glycerol; ii) growth in medium with glycerol as the main carbon source induced a higher resistance to H2O2, a slower growth of mycelia and a lower carbon consumption, as compared to glucose-supplemented medium, during 35 days of

Photo or Solar Ferrioxalate Disinfection Technology without External Hydrogen Peroxide Supply

The Fenton reaction, which refers to the reaction between ferrous ions and hydrogen peroxide to produce the OH radical, has not been widely applied to the disinfection of microorganisms despite being economic and environmentally friendly. Cho et al. have previously proposed the neutral photo ferrioxalate system as a solution to the problems posed by the Fenton reaction in acidic conditions, 1) but this system still requires an external hydrogen peroxide supply. In the present study, we developed a simple disinfection technology using the photo or solar ferrioxalate reaction without the need for an external hydrogen peroxide supply. E. coli was employed as the indicating microorganism. The study results demonstrated the effectiveness of the photo ferrioxalate system in inactivating E. coli without any external hydrogen peroxide supply, as long as dissolved oxygen is supplied. Furthermore, the solar ferrioxalate system achieved faster inactivation of E. coli than an artificial light source at similar irradiance.

Phenol removal using Brassica juncea hairy roots: Role of inherent peroxidase and H2O2

Removal of phenol, a major pollutant in aqueous effluents was studied using plant hairy root cultures. Among four different species of hairy roots tested, Brassica juncea showed the highest potential for phenol removal. The effect of phenol concentration and reuse in a batch system was studied using B. juncea hairy root cultures. Unlike most of the studies reported earlier, phenol removal by the hairy roots was seen to take place without the need for addition of external hydrogen peroxide (H(2)O(2)). To understand the mechanism of phenol removal, levels of peroxidase and phenol oxidase were monitored in the hairy roots. Peroxidase activity in the roots was enhanced when exposed to phenol, while phenol oxidase remained constant. Since peroxidase has a pre-requisite for H(2)O(2), the levels of H(2)O(2) were monitored for its in situ synthesis. H(2)O(2) levels were seen to increase in the presence of phenol. Thus, a mechanism wherein hairy roots also produce H(2)O(2) besides peroxidase, as a protection strategy of plant against xenobiotic stress is plausible.

PerR controls oxidative stress resistance and iron storage proteins and is required for virulence in Staphylococcus aureus.

The Staphylococcus aureus genome encodes three ferric uptake regulator (Fur) homologues: Fur, PerR, and Zur. To determine the exact role of PerR, we inactivated the gene by allelic replacement using a kanamycin cassette, creating strain MJH001 (perR). PerR was found to control transcription of the genes encoding the oxidative stress resistance proteins catalase (KatA), alkyl hydroperoxide reductase (AhpCF), bacterioferritin comigratory protein (Bcp), and thioredoxin reductase (TrxB). Furthermore, PerR regulates transcription of the genes encoding the iron storage proteins ferritin (Ftn) and the ferritin-like Dps homologue, MrgA. Transcription of perR was autoregulated, and PerR repressed transcription of the iron homeostasis regulator Fur, which is a positive regulator of catalase expression. PerR functions as a manganese-dependent, transcriptional repressor of the identified regulon. Elevated iron concentrations produced induction of the PerR regulon. PerR may act as a peroxide sensor, since addition of external hydrogen peroxide to 8325-4 (wild type) resulted in increased transcription of most of the PerR regulon, except for fur and perR itself. The PerR-regulated katA gene encodes the sole catalase of S. aureus, which is an important starvation survival determinant but is surprisingly not required for pathogenicity in a murine skin abscess model of infection. In contrast, PerR is not necessary for starvation survival but is required for full virulence (P < 0.005) in this model of infection. PerR of S. aureus may act as a redox sentinel protein during infection, analogous to the in vitro activities of OxyR and PerR of Escherichia coli and Bacillus subtilis, respectively. However, it differs in its response to the metal balance within the cell and has the added capability of regulating iron uptake and storage.

Metabolism of hydrogen peroxide by the scavenging system in Chlamydomonas reinhardtii

The metabolism of hydrogen peroxide by the scavenging system was studied in Chlamydomonas grown in a selenium‐lacking and a selenium‐containing medium. In cells of the former, 40% of external hydrogen peroxide (H2O2) was scavenged by ascorbate peroxidase (AsAP; EC 1.11.1.11) and the residual H2O2 by catalase (EC 1.11.1.6). The enzymes involved in the ascorbate‐glutathione cycle including AsAP. were localized in the chloroplast. In cells of the latter, glutathione peroxidase (GSHP; EC 1.11.1.9) functioned primarily in the removal of external H2O2. GSHP was located solely in the cytosol. The Chlamydomonas AsAP was relatively stable in ascorbate‐depleted medium as compared with chloroplast AsAP of higher plants. No inactivation of the enzyme was found upon its incubation with hydroxyurea, an inhibitor of the chloroplast enzyme of higher plants. The enzyme showed higher specificity with pyrogallol than with ascorbate. The amino acid sequences in the N‐terminal region of Chlamvdomonas AsAP showed no significant similarity to any other AsAP from higher plants and Euglena. The enzyme had a molecular mass of 34 kDa. The Km values of the enzyme for ascorbate and H2O2 were 5.2±0.3 and 25±3.4 μM, respectively. Hydrogen peroxide was generated at a rate of 6.1±0.8 μmol mg‐1 chlorophyll h‐1 in intact chloroplasts isolated from Chlamydomonas cells grown in the presence of Na‐selenite, and it diffused from the organelles into the medium.

Rat Pleural Mesothelial Cells Show Damage after Exposure to External but Not Internal Cigarette Smoke

The combination of cigarette smoke and high-level occupational asbestos exposure produces a synergistic increase in the incidence of lung cancer; however, smoking does not affect the incidence of mesothelioma. Here we present the results of tests of two theories that have been proposed to explain this phenomenon; namely, that pleural mesothelial cells are resistant to cigarette smoke-induced damage and that the pleural connective tissue acts as a barrier that prevents smoke from reaching the mesothelial cells. To test these hypotheses, excised whole rat lung preparations were exposed to either internal (intratracheal) or external (pleural surface) smoke. For comparison, additional excised lung preparations were exposed to solutions of hydrogen peroxide either externally or intratracheally. Mesothelial cells exposed to external smoke showed widespread, dose-dependent uptake of Trypan blue. Mesothelial cells did not take up Trypan blue after exposure to internal smoke. Bronchial epithelial cells exposed to internal smoke did show uptake, but to a lesser degree than externally exposed mesothelial cells. Examination by scanning and transmission electron microscopy showed that internal smoke did not affect mesothelial cell ultrastructure, whereas external smoke produced obvious mesothelial cell damage and mesothelial cell detachment. Catalase and deferoxamine, scavengers of active oxygen species, provided protection against smoke-induced mesothelial cell injury, but inactivated catalase did not. External hydrogen peroxide produced a very similar, dose-dependent pattern of Trypan blue uptake and ultrastructural changes. Intratracheal hydrogen peroxide also damaged mesothelial cells, but the extent of damage was always less than with comparable concentrations of external hydrogen peroxide.(ABSTRACT TRUNCATED AT 250 WORDS)

Establishment of mouse cell lines homozygous for temperature-sensitive mutation in catalase gene.

Contact-inhibited and-transformed fibroblast cell lines have been established from the homozygous C3H/CSb mutant mouse. These cell lines have low levels of a temperature-sensitive catalase enzyme activity. When compared to wild-type C3H cells, the catalase-deficient cells are markedly more sensitive to the toxicity of hydrogen peroxide. Furthermore, this cellular sensitivity to external hydrogen peroxide is temperature sensitive. These cell lines will be of use in the study of the role which catalase plays in the intracellular prevention of transformation induced by oxidative stress.