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Sample records for cdelta dependent oxidative

  1. Interaction of connexin43 and protein kinase C-delta during FGF2 signaling

    Directory of Open Access Journals (Sweden)

    Stains Joseph P

    2010-03-01

    Full Text Available Abstract Background We have recently demonstrated that modulation of the gap junction protein, connexin43, can affect the response of osteoblasts to fibroblast growth factor 2 in a protein kinase C-delta-dependent manner. Others have shown that the C-terminal tail of connexin43 serves as a docking platform for signaling complexes. It is unknown whether protein kinase C-delta can physically interact with connexin43. Results In the present study, we investigate by immunofluorescent co-detection and biochemical examination the interaction between Cx43 and protein kinase C-delta. We establish that protein kinase C-delta physically interacts with connexin43 during fibroblast growth factor 2 signaling, and that protein kinase C delta preferentially co-precipitates phosphorylated connexin43. Further, we show by pull down assay that protein kinase C-delta associates with the C-terminal tail of connexin43. Conclusions Connexin43 can serve as a direct docking platform for the recruitment of protein kinase C-delta in order to affect fibroblast growth factor 2 signaling in osteoblasts. These data expand the list of signal molecules that assemble on the connexin43 C-terminal tail and provide a critical context to understand how gap junctions modify signal transduction cascades in order to impact cell function.

  2. Human urinary excretion profile after smoking and oral administration of [14C]delta 1-tetrahydrocannabinol

    International Nuclear Information System (INIS)

    The urinary excretion profiles of delta 1-tetrahydrocannabinol (delta 1-THC) metabolites have been evaluated in two chronic and two naive marijuana users after smoking and oral administration of [14C]delta 1-THC. Urine was collected for five days after each administration route and analyzed for total delta 1-THC metabolites by radioactivity determination, for delta 1-THC-7-oic acid by high-performance liquid chromatography, and for cross-reacting cannabinoids by the EMIT d.a.u. cannabinoid assay. The average urinary excretion half-life of 14C-labeled delta 1-THC metabolites was calculated to be 18.2 +/- 4.9 h (+/- SD). The excretion profiles of delta 1-THC-7-oic acid and EMIT readings were similar to the excretion profile of 14C-labeled metabolites in the naive users. However, in the chronic users the excretion profiles of delta 1-THC-7-oic acid and EMIT readings did not resemble the radioactive excretion due to the heavy influence from previous Cannabis use. Between 8-14% of the radioactive dose was recovered in the urine in both user groups after oral administration. Lower urinary recovery was obtained both in the chronic and naive users after smoking--5 and 2%, respectively

  3. Temperature-Dependent Photoluminescence of Graphene Oxide

    Science.gov (United States)

    Jadhav, S. T.; Rajoba, S. J.; Patil, S. A.; Han, S. H.; Jadhav, L. D.

    2016-01-01

    Graphene oxide thin films have been deposited by spray pyrolysis using graphene oxide powder prepared by modified Hummers method. These thin films were characterized by different physico-chemical techniques. The x-ray diffraction studies revealed the structural properties of GO (graphene oxide) while the Raman spectrum showed the presence of D and G and two-dimensional bands. The D/G intensity ratio for spray-deposited GO film is 1.10. The x-ray photoelectron spectroscopy showed 67% and 33% atomic percentages of carbon and oxygen, respectively. The ratio of O1s/C1s was found to be 0.49. The temperature-dependent photoluminescence of GO thin film and GO solution showed a blue emission.

  4. TEOS-based oxides: deposition dependent properties

    International Nuclear Information System (INIS)

    This paper reports the effects of three important parameters, deposition temperature, TEOS concentration and RF power in the plasma enhanced CVD of TEOS-based oxides on the resulting film characteristics such as impurity incorporation, film density, moisture absorption, intrinsic and thermal stresses. Ion-bombardment induced desorption of reactive precursor species is suggested to occur under certain conditions. Further, it is shown that the film properties continue to evolve until the film thickness exceeds 3000A. For 1 μm films deposited using typical settings of deposition parameters, the average TCE is estimated to be 0.9 ppm/ C using the stress-temperature characteristics. (orig.)

  5. Human urinary excretion profile after smoking and oral administration of ( sup 14 C)delta 1-tetrahydrocannabinol

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, E.; Gillespie, H.K.; Halldin, M.M. (BMC, Uppsala (Sweden))

    1990-05-01

    The urinary excretion profiles of delta 1-tetrahydrocannabinol (delta 1-THC) metabolites have been evaluated in two chronic and two naive marijuana users after smoking and oral administration of ({sup 14}C)delta 1-THC. Urine was collected for five days after each administration route and analyzed for total delta 1-THC metabolites by radioactivity determination, for delta 1-THC-7-oic acid by high-performance liquid chromatography, and for cross-reacting cannabinoids by the EMIT d.a.u. cannabinoid assay. The average urinary excretion half-life of {sup 14}C-labeled delta 1-THC metabolites was calculated to be 18.2 +/- 4.9 h (+/- SD). The excretion profiles of delta 1-THC-7-oic acid and EMIT readings were similar to the excretion profile of {sup 14}C-labeled metabolites in the naive users. However, in the chronic users the excretion profiles of delta 1-THC-7-oic acid and EMIT readings did not resemble the radioactive excretion due to the heavy influence from previous Cannabis use. Between 8-14% of the radioactive dose was recovered in the urine in both user groups after oral administration. Lower urinary recovery was obtained both in the chronic and naive users after smoking--5 and 2%, respectively.

  6. Anaerobic Nitrate-Dependent Metal Bio-Oxidation

    Science.gov (United States)

    Weber, K.; Knox, T.; Achenbach, L. A.; Coates, J. D.

    2007-12-01

    Direct biological oxidation of reduced metals (Fe(II) and U(IV)) coupled to nitrate reduction at circumneutral pH under anaerobic conditions has been recognized in several environments as well as pure culture. Several phylogentically diverse mesophilic bacteria have been described as capable of anaerobic, nitrate-dependent Fe(II) oxidation (NFOx). Our recent identification of a freshwater mesophilic, lithoautotroph, Ferrutens nitratireducens strain 2002, capable of growth through NFOx presents an opportunity to further study metal bio- oxidation. Continuing physiological studies revealed that in addition to Fe(II) oxidation, strain 2002 is capable of oxidizing U(IV) (4 μM) in washed cell suspensions with nitrate serving as the electron acceptor. Pasteurized cultures exhibited abiotic oxidation of 2 μM U(IV). Under growth conditions, strain 2002 catalyzed the oxidation of 12 μM U(IV) within a two week period. Cultures amended with sodium azide, an electron transport inhibitor, demonstrated limited oxidation (7 μM) similar to pasteurized cultures, supporting the direct role of electron transport in U(IV) bio-oxidation. The oxidation of U(IV) coupled denitrification at circumneutral pH would yield enough energy to support anaerobic microbial growth (ΔG°'= -460.36 kJ/mole). It is currently unknown whether or not strain 2002 can couple this metabolism to growth. The growth of F. nitratireducens strain 2002 utilizing Fe(II) as the sole electron donor was previously demonstrated. The amount of U(IV) (~12 μM) that strain 2002 oxidized under similar autotrophic growth conditions yields 0.0019 kJ, enough energy for the generation of ATP (5.3 x 10-20 kJ ATP-1), but not enough energy for cell replication as calculated for nitrate-dependent Fe(II) oxidizing conditions (0.096 kJ) assuming a similar metabolism. In addition to F. nitratireducens strain 2002, a nitrate-dependent Fe(II) oxidizing bacterium isolated from U contaminated groundwater, Diaphorobacter sp. strain

  7. [Inhalation of nitric oxide - dependence: case report

    Science.gov (United States)

    Carvalho, W B; Matsumoto, T; Horita, S M; Almeida, N M; Martins, F R

    2000-01-01

    OBJECTIVE: Describe the hemodynamic response with rebound of pulmonary hypertension after withdrawal of inhaled nitric oxide (NO) in a pediatric patient with acute respiratory distress syndrome (ARDS). METHODS: Case report of a child with ARDS and pulmonary hypertension evaluated through ecocardiografic with dopller, receiving inhaled NO for a period of 21 days. RESULTS: There was a decrease of the pulmonary artery pressure (PAP) from 52 mmHg to 44 mmHg after the initial titulation of NO inhalation dose. After the withdrawal of inhaled NO an elevation of PAP was observed (55 mmHg). It was necessary to reinstall the inhaled NO to obtain a more appropriate value (34 mmHg). A new attempt of interruption of the inhaled NO after prolonged inhalation (20 days) resulted in a new clinic worsening and increase of PAP, with the indication to reinstall the inhaled NO. In the 24th day of permanence in the intensive care unit the patient died due to multiple organ dysfunction. CONCLUSIONS: The possibility of pulmonary hypertension rebound after withdrawal of inhaled NO is a complication that may have important clinical implications for patients who need a prolonged treatment with NO. This case report emphasizes these implications. PMID:14647690

  8. The burnup dependence of light water reactor spent fuel oxidation

    International Nuclear Information System (INIS)

    Over the temperature range of interest for dry storage or for placement of spent fuel in a permanent repository under the conditions now being considered, UO2 is thermodynamically unstable with respect to oxidation to higher oxides. The multiple valence states of uranium allow for the accommodation of interstitial oxygen atoms in the fuel matrix. A variety of stoichiometric and nonstoichiometric phases is therefore possible as the fuel oxidizers from UO2 to higher oxides. The oxidation of UO2 has been studied extensively for over 40 years. It has been shown that spent fuel and unirradiated UO2 oxidize via different mechanisms and at different rates. The oxidation of LWR spent fuel from UO2 to UO2.4 was studied previously and is reasonably well understood. The study presented here was initiated to determine the mechanism and rate of oxidation from UO2.4 to higher oxides. During the early stages of this work, a large variability in the oxidation behavior of samples oxidized under nearly identical conditions was found. Based on previous work on the effect of dopants on UO2 oxidation and this initial variability, it was hypothesized that the substitution of fission product and actinide impurities for uranium atoms in the spent fuel matrix was the cause of the variable oxidation behavior. Since the impurity concentration is roughly proportional to the burnup of a specimen, the oxidation behavior of spent fuel was expected to be a function of both temperature and burnup. This report (1) summarizes the previous oxidation work for both unirradiated UO2 and spent fuel (Section 2.2) and presents the theoretical basis for the burnup (i.e., impurity concentration) dependence of the rate of oxidation (Sections 2.3, 2.4, and 2.5), (2) describes the experimental approach (Section 3) and results (Section 4) for the current oxidation tests on spent fuel, and (3) establishes a simple model to determine the activation energies associated with spent fuel oxidation (Section 5)

  9. Angular dependence of silicon oxide etching yield in fluorocarbon chemistries

    International Nuclear Information System (INIS)

    High density fluorocarbon plasma for silicon oxide etching has various ion and neutral species. Profile evolution modeling can provide understanding of many difficulties caused by the complexity of the plasma in etching. In this research we have measured etching and deposition rates as functions of ion impinging angle, sample temperature, which are necessary for profile evolution modeling of silicon oxide etching in inductively coupled plasma. Angular dependence of etching yield of oxide in fluorocarbon plasma shows very unique behavior unlike typical ion-induced chemical etching or physical sputtering. Ion-induced deposition model is suggested and tested

  10. Soluble and immobilized graphene oxide activates complement system differently dependent on surface oxidation state

    DEFF Research Database (Denmark)

    Wibroe, Peter Popp; Petersen, Søren Vermehren; Bovet, Nicolas Emile;

    2016-01-01

    Graphene oxide (GO) is believed to become applicable in biomedical products and medicine, thereby necessitating appropriate safety evaluation dependent on their applications and the route of administration. We have examined the effect of GO form (in solution versus immobilized) and oxidation state...

  11. Fluence dependence of deuterium retention in oxidized SS-316

    Science.gov (United States)

    Oya, Yasuhisa; Suzuki, Sachiko; Matsuyama, Masao; Hayashi, Takumi; Yamanishi, Toshihiko; Asakura, Yamato; Okuno, Kenji

    2011-10-01

    The ion fluence dependence of deuterium retention in SS-316 during oxidation at a temperature of 673 K was studied to evaluate the dynamics of deuterium retention in the oxide layer of SS-316. The correlation between the chemical state of stainless steel and deuterium retention was evaluated using XPS and TDS. It was found that the major deuterium desorption temperatures were located at around 660 K and 935 K, which correspond to the desorption of deuterium trapped as hydroxide. The deuterium retention increased with increasing deuterium ion fluence, since the deuterium retention as hydroxide increased significantly. However, retention saturated at an ion fluence of ˜2.5 × 10 21 D + m -2. The XPS result showed that FeOOD was formed on the surface, although pure Fe also remained in the oxide layer. These facts indicate the nature of the oxide layer have a key role in deuterium trapping behavior.

  12. Performance of sulfate-dependent anaerobic ammo-nium oxidation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lei; ZHENG Ping; HE YuHui; JIN RenCun

    2009-01-01

    The performance of sulfate-dependent anaerobic ammonium oxidation was studied. The results showed that both SO42- and NH4+ were chemically stable under anaerobic conditions. They did not react with each other in the absence of biological catalyst (sludge). The anaerobic digested sludge cultivated in an anaerobic reactor for three years took on the ability of oxidizing ammonium with sulfate anaero-bically. The average reduction of sulfate and ammonium was 71.67 mg.L-1 and 56.82 mg.L-1 at high concentrations.The reaction between SO42- and NH4+ was difficult, though feasible, due to its low standard Gibbs free energy change. The experiment demonstrated that high substrate concentrations and low oxidation-reduction potential (ORP) may be favourable for the biological reaction.

  13. Performance of sulfate-dependent anaerobic ammonium oxidation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The performance of sulfate-dependent anaerobic ammonium oxidation was studied.The results showed that both SO42-and NH4+ were chemically stable under anaerobic conditions.They did not react with each other in the absence of biological catalyst(sludge).The anaerobic digested sludge cultivated in an anaerobic reactor for three years took on the ability of oxidizing ammonium with sulfate anaero-bically.The average reduction of sulfate and ammonium was 71.67 mg.L-1 and 56.82 mg.L-1 at high concentrations.The reaction between SO42-and NH4+ was difficult,though feasible,due to its low standard Gibbs free energy change.The experiment demonstrated that high substrate concentrations and low oxidation-reduction potential(ORP) may be favourable for the biological reaction.

  14. Nitric oxide: Orchestrator of endothelium-dependent responses

    DEFF Research Database (Denmark)

    Félétou, Michel; Köhler, Ralf; Vanhoutte, Paul M

    2012-01-01

    interventions may improve the bioavailability of NO and thus prevent/cure endothelial dysfunction. Then, the role of other endothelium-derived mediators (endothelium-derived hyperpolarizing (EDHF) and contracting (EDCF) factors, endothelin-1) and signals (myoendothelial coupling) is summarized also, with......Abstract The present review first summarizes the complex chain of events, in endothelial and vascular smooth muscle cells, that leads to endothelium-dependent relaxations (vasodilatations) due to the generation of nitric oxide (NO) by endothelial nitric oxide synthase (eNOS) and how therapeutic...... special emphasis on their interaction(s) with the NO pathway, which make the latter not only a major mediator but also a key regulator of endothelium-dependent responses....

  15. Crystal habit dependent quantum confined photoluminescence of zinc oxide nanostructures

    International Nuclear Information System (INIS)

    Diverse zinc oxide crystal habits namely wire, rods, tubes, whiskers and tetrapods were synthesized via hydrothermal and carbothermal reduction routes. A vapor current induced regionalization in the carbothermal synthesis lead to the isolation of these crystal habits for characterization. The surface morphology of the nanostructures was analyzed via field emission scanning electron microscopy (FESEM). The morphology and crystallinity of the as-synthesized nanostructure architectural motifs were related to their photoluminescence (PL). The photoluminescence at 157 nm was taken using F2 excimer laser and a crystal habit dependent response was observed. X-ray diffraction (XRD) analyses were conducted to deduce the degree of crystallinity showing results consistent with the excitonic emission at the band edge and visible emission at the electron-hole recombination sites. The presence of minimal crystal defects which gave the green emission was supported by energy dispersive spectroscopy (EDS) data. Transmission spectroscopy for the tetrapods exhibited an interesting PL reduction associated with high-energy deep traps in the nanostructures. Furthermore, some intensity dependent characteristics were deduced indicating quantum confined properties of these nano structures. (author)

  16. Anaerobic, Nitrate-Dependent Oxidation of U(IV) Oxide Minerals by the Chemolithoautotrophic Bacterium Thiobacillus denitrificans

    Energy Technology Data Exchange (ETDEWEB)

    Beller, H R

    2004-06-25

    Under anaerobic conditions and at circumneutral pH, cells of the widely-distributed, obligate chemolithoautotrophic bacterium Thiobacillus denitrificans oxidatively dissolved synthetic and biogenic U(IV) oxides (uraninite) in nitrate-dependent fashion: U(IV) oxidation required the presence of nitrate and was strongly correlated to nitrate consumption. This is the first report of anaerobic U(IV) oxidation by an autotrophic bacterium.

  17. Concentration-dependent toxicity of iron oxide nanoparticles mediated by increased oxidative stress

    Directory of Open Access Journals (Sweden)

    Saba Naqvi

    2010-11-01

    Full Text Available Saba Naqvi1, Mohammad Samim2, MZ Abdin3, Farhan Jalees Ahmed4, AN Maitra5, CK Prashant6, Amit K Dinda61Faculty of Engineering and Interdisciplinary Sciences, 2Department of Chemistry, 3Department of Biotechnology, Faculty of Science, 4Department of Pharmaceutics, Faculty of Pharmacy, Jamia Hamdard, Hamdard University, 5Department of Chemistry, University of Delhi, 6Department of Pathology, All India Institute of Medical Sciences, New Delhi, IndiaAbstract: Iron oxide nanoparticles with unique magnetic properties have a high potential for use in several biomedical, bioengineering and in vivo applications, including tissue repair, magnetic resonance imaging, immunoassay, drug delivery, detoxification of biologic fluids, cell sorting, and hyperthermia. Although various surface modifications are being done for making these nonbiodegradable nanoparticles more biocompatible, their toxic potential is still a major concern. The current in vitro study of the interaction of superparamagnetic iron oxide nanoparticles of mean diameter 30 nm coated with Tween 80 and murine macrophage (J774 cells was undertaken to evaluate the dose- and time-dependent toxic potential, as well as investigate the role of oxidative stress in the toxicity. A 15–30 nm size range of spherical nanoparticles were characterized by transmission electron microscopy and zeta sizer. MTT assay showed >95% viability of cells in lower concentrations (25–200 µg/mL and up to three hours of exposure, whereas at higher concentrations (300–500 µg/mL and prolonged (six hours exposure viability reduced to 55%–65%. Necrosis-apoptosis assay by propidium iodide and Hoechst-33342 staining revealed loss of the majority of the cells by apoptosis. H2DCFDDA assay to quantify generation of intracellular reactive oxygen species (ROS indicated that exposure to a higher concentration of nanoparticles resulted in enhanced ROS generation, leading to cell injury and death. The cell membrane injury

  18. Nitric oxide, cholesterol oxides and endothelium-dependent vasodilation in plasma of patients with essential hypertension

    Directory of Open Access Journals (Sweden)

    P. Moriel

    2002-11-01

    Full Text Available The objective of the present study was to identify disturbances of nitric oxide radical (·NO metabolism and the formation of cholesterol oxidation products in human essential hypertension. The concentrations of·NO derivatives (nitrite, nitrate, S-nitrosothiols and nitrotyrosine, water and lipid-soluble antioxidants and cholesterol oxides were measured in plasma of 11 patients with mild essential hypertension (H: 57.8 ± 9.7 years; blood pressure, 148.3 ± 24.8/90.8 ± 10.2 mmHg and in 11 healthy subjects (N: 48.4 ± 7.0 years; blood pressure, 119.4 ± 9.4/75.0 ± 8.0 mmHg.Nitrite, nitrate and S-nitrosothiols were measured by chemiluminescence and nitrotyrosine was determined by ELISA. Antioxidants were determined by reverse-phase HPLC and cholesterol oxides by gas chromatography. Hypertensive patients had reduced endothelium-dependent vasodilation in response to reactive hyperemia (H: 9.3 and N: 15.1% increase of diameter 90 s after hyperemia, and lower levels of ascorbate (H: 29.2 ± 26.0, N: 54.2 ± 24.9 µM, urate (H: 108.5 ± 18.9, N: 156.4 ± 26.3 µM, ß-carotene (H: 1.1 ± 0.8, N: 2.5 ± 1.2 nmol/mg cholesterol, and lycopene (H: 0.4 ± 0.2, N: 0.7 ± 0.2 nmol/mg cholesterol, in plasma, compared to normotensive subjects. The content of 7-ketocholesterol, 5alpha-cholestane-3ß,5,6ß-triol and 5,6alpha-epoxy-5alpha-cholestan-3alpha-ol in LDL, and the concentration of endothelin-1 (H: 0.9 ± 0.2, N: 0.7 ± 0.1 ng/ml in plasma were increased in hypertensive patients. No differences were found for ·NO derivatives between groups. These data suggest that an increase in cholesterol oxidation is associated with endothelium dysfunction in essential hypertension and oxidative stress, although ·NO metabolite levels in plasma are not modified in the presence of elevated cholesterol oxides.

  19. Effect of oxide/oxide interface on polarity dependent resistive switching behavior in ZnO/ZrO2 heterostructures

    Science.gov (United States)

    Xu, Zedong; Yu, Lina; Xu, Xiaoguang; Miao, Jun; Jiang, Yong

    2014-05-01

    The effect of oxide/oxide interface for controlling the migration process of oxygen vacancies (or oxygen ions) on resistive switching behaviors has been investigated by fabricating the ZrO2/ZnO oxide heterostructures. Completely different resistive switching behaviors are observed in the heterostructures with a set process under a different bias polarity. It is demonstrated that the change of the oxide/oxide interface barrier height determining the migration of oxygen vacancies (or oxygen ions) leads to the current direction-dependent resistive switching. Furthermore, the ZnO/ZrO2 heterostructure with the homogeneous resistive switching behavior could be potentially applied as a controllable and stable multistate memory by controlling reset-stop voltages. Our method opens up an opportunity to explore the resistive switching mechanism and develop resistance switching devices with specific functions through engineering oxide/oxide interfaces in oxide heterostructures.

  20. The toxicity of graphene oxides: dependence on the oxidative methods used.

    Science.gov (United States)

    Chng, Elaine Lay Khim; Pumera, Martin

    2013-06-17

    Graphene, a class of two-dimensional carbon nanomaterial, has attracted extensive interest in recent years, with a significant amount of research focusing on graphene oxides (GOs). They have been primed as potential candidates for biomedical applications such as cell labeling and drug delivery, thus the toxicity and behavior of graphene oxides in biological systems are fundamental issues that need urgent attention. The production of GO is generally achieved through a top-down route, which includes the usage of concentrated H₂SO₄ along with: 1) concentrated nitric acid and KClO₃ oxidant (Hoffmann); 2) fuming nitric acid and KClO₃ oxidant (Staudenmaier); 3) concentrated phosphoric acid with KMnO₄ (Tour); or 4) sodium nitrate for in-situ production of nitric acid in the presence of KMnO₄ (Hummers). It has been widely assumed that the properties of these four GOs produced by using the above different methods are roughly similar, so the methods have been used interchangeably. However, several studies have reported that the toxicity of graphene-related nanomaterials in biological systems may be influenced by their physiochemical properties, such as surface functional groups and structural defects. In addition, considering how GOs are increasingly used in the field of biomedicine, we are interested to see how the oxygen content/functional groups of GOs can impact their toxicological profiles. Since in-vitro testing is a common first step in assessing the health risks related with engineered nanomaterials, the cytotoxicity of the GOs prepared by the four different oxidative treatments was investigated by measuring the mitochondrial activity in adherent lung epithelial cells (A549) by using commercially available viability assays. The dose-response data was generated by using two assays, the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and the water-soluble tetrazolium salt (WST-8). From the viability data, it is evident that there is a strong dose-dependent

  1. Stress dependent oxidation of sputtered niobium and effects on superconductivity

    International Nuclear Information System (INIS)

    We report on the suppression of room temperature oxidation of DC sputtered niobium films and the effects upon the superconductive transition temperature, Tc. Niobium was sputter-deposited on silicon dioxide coated 150 mm wafers and permitted to oxidize at room temperature and pressure for up to two years. Resistivity and stress measurements indicate that tensile films greater than 400 MPa resist bulk oxidation with measurements using transmission electron microscope, electron dispersive X-ray spectroscopy, x-ray photoelectric spectroscopy, and secondary ion mass spectrometry confirming this result. Although a surface oxide, Nb2O5, consumed the top 6–10 nm, we measure less than 1 at. % oxygen and nitrogen in the bulk of the films after the oxidation period. Tc measurements using a SQUID magnetometer indicate that the tensile films maintained a Tc approaching the dirty superconductive limit of 8.4 K after two years of oxidation while maintaining room temperature sheet resistance. This work demonstrates that control over niobium film stress during deposition can prevent bulk oxidation by limiting the vertical grain boundaries ability to oxidize, prolonging the superconductive properties of sputtered niobium when exposed to atmosphere

  2. Stress dependent oxidation of sputtered niobium and effects on superconductivity

    Science.gov (United States)

    David Henry, M.; Wolfley, Steve; Monson, Todd; Clark, Blythe G.; Shaner, Eric; Jarecki, Robert

    2014-02-01

    We report on the suppression of room temperature oxidation of DC sputtered niobium films and the effects upon the superconductive transition temperature, Tc. Niobium was sputter-deposited on silicon dioxide coated 150 mm wafers and permitted to oxidize at room temperature and pressure for up to two years. Resistivity and stress measurements indicate that tensile films greater than 400 MPa resist bulk oxidation with measurements using transmission electron microscope, electron dispersive X-ray spectroscopy, x-ray photoelectric spectroscopy, and secondary ion mass spectrometry confirming this result. Although a surface oxide, Nb2O5, consumed the top 6-10 nm, we measure less than 1 at. % oxygen and nitrogen in the bulk of the films after the oxidation period. Tc measurements using a SQUID magnetometer indicate that the tensile films maintained a Tc approaching the dirty superconductive limit of 8.4 K after two years of oxidation while maintaining room temperature sheet resistance. This work demonstrates that control over niobium film stress during deposition can prevent bulk oxidation by limiting the vertical grain boundaries ability to oxidize, prolonging the superconductive properties of sputtered niobium when exposed to atmosphere.

  3. Sr flux stability against oxidation in oxide-MBE environment: flux, geometry, and pressure dependence

    OpenAIRE

    Kim, Y.S.; Bansal, Namrata; Chaparro, Carlos; Gross, Heiko; Oh, Seongshik

    2011-01-01

    Maintaining stable fluxes for multiple source elements is a challenging task when the source materials have significantly different oxygen affinities in a complex-oxide molecular-beam-epitaxy (MBE) environment. Considering that Sr is one of the most easily oxidized and widely used element in various complex oxides, we took Sr as a probe to investigate the flux stability problem in a number of different conditions. Source oxidation was less for higher flux, extended port geometry, and un-melte...

  4. Composition dependence of methanol oxidation activity in nickel–cobalt hydroxides and oxides: an optimization toward highly active electrodes

    International Nuclear Information System (INIS)

    Graphical Abstract: Display Omitted - Abstract: Non-precious metal electrodes, Ni and Co hydroxides and oxides, have been recently found active towards electro-oxidation of methanol in alkaline. In this article, we present a first and complete study on composition dependence of Ni–Co hydroxides and oxides for methanol electro-oxidation. Ni–Co hydroxide electrodes were prepared by co-electrodeposition on stainless steel mesh (SSM). The atomic ratio of Ni/Ni + Co in Ni–Co hydroxides was controlled by adjusting the ratio of precursor concentration. Ni–Co oxide electrodes were further obtained by annealing the Ni–Co hydroxides. The morphology factors of Ni–Co hydroxides and oxides were revealed by measuring double layer capacitance using cyclic voltammetry (CV). Methanol oxidation reaction (MOR) performance of these Ni–Co hydroxides and oxide electrodes was investigated by CV, and electrochemical impedance spectroscopy (EIS) techniques at room temperature (RT, ∼25 °C). It is found that the MOR performance of Ni–Co hydroxides increased with the increase of Ni content, while the performance of Ni–Co oxide electrodes presented a volcano plot. The highest MOR performance, the smallest charge transfer resistance and Tafel slope were found at the atomic composition of 46% Ni. Such an enhancement probably was due to the synergistic effect of co-existing Ni and Co in the spinel structure. In contrast, the electrode with the mixture of Ni oxide and Co oxide was unable to reach such a high activity. The function of Ni in Ni–Co hydroxides and oxides was attributed to facilitating the methanol oxidation, and in low potential it presented high absorption of intermediate products

  5. Differences in oxidative stress dependence between gastric adenocarcinoma subtypes

    Institute of Scientific and Technical Information of China (English)

    Brigitte Bancel; Jacques Estève; Jean-Christophe Souquet; Shinya Toyokuni; Hiroshi Ohshima; Brigitte Pignatelli

    2006-01-01

    AIM: To investigate the extent of oxidative stress in preneoplastic and neoplastic gastric mucosa in relation to their pathological criteria and histological subtypes.METHODS: A total of 104 gastric adenocarcinomas from 98 patients (88 infiltrative and 16 intraepithelial tumors)were assessed immunohistochemically for expression of iNOS and occurrence of nitrotyrosine (NTYR)-containing proteins and 8-hydroxy-2'-deoxyguanosine (8-OHdG)-containing DNA, as markers of NO production and damages to protein and DNA.RESULTS: Tumor cells staining for iNOS, NTYR and 8-OH-dG were detected in 41%, 62% and 50% of infiltrative carcinoma, respectively. The three markers were shown for the first time in intraepithelial carcinoma.The expression of iNOS was significantly more frequent in tubular carcinoma (TC) compared to diffuse carcinoma (DC) (54% vs 18%; P=0.008) or in polymorphous carcinoma (PolyC) (54% vs 21%; P=0.04). NTYR staining was obviously more often found in TC than that in PolyC (72% vs 30%; P=0.03). There was a tendency towards a higher rate of iNOS staining when distant metastasis (pM) was present. In infiltrative TC, the presence of oxidative stress markers was not significantly correlated with histological grade, density of inflammation, the depth of infiltration (pT), lymph nodes dissemination (pN) and pathological stages (pTNM).CONCLUSION: The iNOS-oxidative pathway may play an important role in TC, but moderately in PolyC and DC.DNA oxidation and protein nitration occur in the three subtypes. Based on the significant differences of NTYR levels, TC and PolyC appear as two distinct subtypes.

  6. Structural dependence of photocatalytic properties of tungsten oxide

    Czech Academy of Sciences Publication Activity Database

    Domlátil, J.; Brožek, Vlastimil; Janča, J.; Eliáš, M.

    Praha : CSCA, 2006 - (Nitsch, K.; Rodová, M.), s. 20-21 ISBN 80-901-748-7-6. [Development of Materials Science in Research and Education, Joint Seminar 2006 /16./. Valtice (CZ), 12.09.2006-15.09.2006] R&D Projects: GA ČR(CZ) GA104/05/0540 Institutional research plan: CEZ:AV0Z20430508 Keywords : tungsten oxides * photocatalytic activity * thermal plasma * photoactivity measurement Subject RIV: JJ - Other Materials

  7. Size dependent magnetic properties of iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Jhunu; Haik, Yousef. E-mail: haik@eng.fsu.edu; Chen, C.-J.Ching-Jen

    2003-02-01

    {gamma}Fe{sub 2}O{sub 3} nanoparticles has been synthesized by a combination of chemical and ultrasonication procedure and further stabilized with surfactant. Their magnetic properties are compared with the different fractions (10-12, 20-30, 100-150 nm) of commercially available iron oxide. The sizes obtained from the scanning transmission electron micrographs are correlated with the magnetic properties of the particles.

  8. Individual whey protein components influence lipid oxidation dependent on pH

    OpenAIRE

    Horn, Anna Frisenfeldt; Nielsen, Nina Skall; Jacobsen, Charlotte

    2012-01-01

    In emulsions, lipid oxidation is expected to be initiated at the oil-water interface. The properties of the emulsifier used and the composition at the interface is therefore expected to be of great importance for the resulting oxidation. Previous studies have shown that individual whey protein components (α-lactalbumin and β-lactoglobulin) adsorb differently to the interface depending on pH. In addition, differences has been shown to exists between the oxidative stability provided by α-lactal...

  9. HIF-dependent Anti-tumorigenic Effect of Anti-oxidants In Vivo

    OpenAIRE

    Gao, Ping; Zhang, Huafeng; Dinavahi, Ramani; Li, Feng; Xiang, Yan; Raman, Venu; Bhujwalla, Zaver M; Felsher, Dean W.; Cheng, Linzhao; Pevsner, Jonathan; Lee, Linda A; Semenza, Gregg L.; Dang, Chi V.

    2007-01-01

    The anti-tumorigenic activity of anti-oxidants has been presumed to arise from their ability to squelch DNA damage and genomic instability mediated by reactive oxygen species (ROS). Here we report that anti-oxidants inhibited three tumorigenic models in vivo. Inhibition of a MYC-dependent human B lymphoma model was unassociated with genomic instability, but was linked to diminished hypoxia inducible factor (HIF)-1 levels in a prolyl hydroxylase 2 and von Hippel-Lindau protein dependent manner...

  10. Trace methane oxidation and the methane dependency of sulfate reduction in anaerobic granular sludge

    KAUST Repository

    Meulepas, Roel J.W.

    2010-05-01

    This study investigates the oxidation of labeled methane (CH4) and the CH4 dependence of sulfate reduction in three types of anaerobic granular sludge. In all samples, 13C-labeled CH4 was anaerobically oxidized to 13C-labeled CO2, while net endogenous CH4 production was observed. Labeled-CH4 oxidation rates followed CH4 production rates, and the presence of sulfate hampered both labeled-CH4 oxidation and methanogenesis. Labeled-CH4 oxidation was therefore linked to methanogenesis. This process is referred to as trace CH4 oxidation and has been demonstrated in methanogenic pure cultures. This study shows that the ratio between labeled-CH4 oxidation and methanogenesis is positively affected by the CH4 partial pressure and that this ratio is in methanogenic granular sludge more than 40 times higher than that in pure cultures of methanogens. The CH4 partial pressure also positively affected sulfate reduction and negatively affected methanogenesis: a repression of methanogenesis at elevated CH4 partial pressures confers an advantage to sulfate reducers that compete with methanogens for common substrates, formed from endogenous material. The oxidation of labeled CH 4 and the CH4 dependence of sulfate reduction are thus not necessarily evidence of anaerobic oxidation of CH4 coupled to sulfate reduction. © 2010 Federation of European Microbiological Societies.

  11. Doping dependent tunneling conductance in SDW ordered copper oxide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Rout, G.C., E-mail: gcr@iopb.res.in [Condensed Matter Physics Group, Dept. of Applied Physics and Ballistics, F.M. University, 756 019 Balasore, Orissa (India); Panda, S.K. [K.D. Science College, Pochilima, Hinjilicut, 761 101 Ganjam, Orissa (India)

    2011-07-15

    The model calculation reports the co-existences of s-wave superconductivity and spin density wave (SDW) in high-T{sub c} cuprates. The doping dependence of the phase diagram explains the experimental observations qualitatively. The calculated tunneling spectra explains the observed multiple peak structures. This calculation provides an alternative to BCS formalism to calculate order parameters from the spectra. It is observed that doping suppresses the long range anti-ferromagnetic order and induces superconducting phase for a suitable doping. In order to study this effect, we present a model study of the doping dependence of the tunneling conductance in high-T{sub c} systems. The system is described by the Hamiltonian consisting of spin density wave (SDW) and s-wave type superconducting interaction in presence of varying impurity concentrations. The gap equations are calculated by using Green's functions technique of Zubarev. The gap equations and the chemical potential are solved self-consistently. The imaginary part of the electron Green's functions shows the quasi-particle density of states which represent the tunneling conductance observed by the scanning tunneling microscopy (STM). We investigate the effect of impurity on the gap equations as well as on the tunneling conductance. The results will be discussed based on the experimental observations.

  12. Spin-dependent transport in oxide-based tunnel junctions

    OpenAIRE

    Galceran Vercher, Regina

    2015-01-01

    Aquesta tesi estudia les propietats de magnetotransport en unions túnel on un dels elèctrodes és l’òxid ferromagnètic La0.7Sr0.3MnO3 (LSMO). En concret, ens interessem per dos fenòmens diferents: (i) magnetoresistència (MR) en unions túnel amb un sol elèctrode magnètic i (ii) filtratge d’espí en unions túnel magnètiques. L’efecte túnel és extremadament dependent de les interfícies i una bona qualitat de les heteroestructures resulta crucial per a obtenir un bon rendiment dels dispositius. És ...

  13. Application of Iron Oxide as a pH-dependent Indicator for Improving the Nutritional Quality

    Science.gov (United States)

    2016-01-01

    Acid food indicators can be used as pH indicators for evaluating the quality and freshness of fermented products during the full course of distribution. Iron oxide particles are hardly suspended in water, but partially or completely agglomerated. The agglomeration degree of the iron oxide particles depends on the pH. The pH-dependent particle agglomeration or dispersion can be useful for monitoring the acidity of food. The zeta potential of iron oxide showed a decreasing trend as the pH increased from 2 to 8, while the point of zero charge (PZC) was observed around at pH 6.0-7.0. These results suggested that the size of the iron oxide particles was affected by the change in pH levels. As a result, the particle sizes of iron oxide were smaller at lower pH than at neutral pH. In addition, agglomeration of the iron oxide particles increased as the pH increased from 2 to 7. In the time-dependent aggregation test, the average particle size was 730.4 nm and 1,340.3 nm at pH 2 and 7, respectively. These properties of iron oxide particles can be used to develop an ideal acid indicator for food pH and to monitor food quality, besides a colorant or nutrient for nutrition enhancement and sensory promotion in food industry. PMID:27482521

  14. Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

    International Nuclear Information System (INIS)

    Highlights: • Spherical and sheet shaped copper oxide nanoparticles were synthesized. • Physical characterizations of these nanoparticles were done by TEM, DLS, XRD, FTIR. • They showed shape dependent antibacterial activity on different bacterial strain. • They induced both membrane damage and ROS mediated DNA damage in bacteria. - Abstract: In this work, we synthesized spherical and sheet shaped copper oxide nanoparticles and their physical characterizations were done by the X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The antibacterial activity of these nanoparticles was determined on both gram positive and gram negative bacterial. Spherical shaped copper oxide nanoparticles showed more antibacterial property on gram positive bacteria where as sheet shaped copper oxide nanoparticles are more active on gram negative bacteria. We also demonstrated that copper oxide nanoparticles produced reactive oxygen species in both gram negative and gram positive bacteria. Furthermore, they induced membrane damage as determined by atomic force microscopy and scanning electron microscopy. Thus production of and membrane damage are major mechanisms of the bactericidal activity of these copper oxide nanoparticles. Finally it was concluded that antibacterial activity of nanoparticles depend on physicochemical properties of copper oxide nanoparticles and bacterial strain

  15. Light-Dependent Aerobic Methane Oxidation Reduces Methane Emissions from Seasonally Stratified Lakes.

    Directory of Open Access Journals (Sweden)

    Kirsten Oswald

    Full Text Available Lakes are a natural source of methane to the atmosphere and contribute significantly to total emissions compared to the oceans. Controls on methane emissions from lake surfaces, particularly biotic processes within anoxic hypolimnia, are only partially understood. Here we investigated biological methane oxidation in the water column of the seasonally stratified Lake Rotsee. A zone of methane oxidation extending from the oxic/anoxic interface into anoxic waters was identified by chemical profiling of oxygen, methane and δ13C of methane. Incubation experiments with 13C-methane yielded highest oxidation rates within the oxycline, and comparable rates were measured in anoxic waters. Despite predominantly anoxic conditions within the zone of methane oxidation, known groups of anaerobic methanotrophic archaea were conspicuously absent. Instead, aerobic gammaproteobacterial methanotrophs were identified as the active methane oxidizers. In addition, continuous oxidation and maximum rates always occurred under light conditions. These findings, along with the detection of chlorophyll a, suggest that aerobic methane oxidation is tightly coupled to light-dependent photosynthetic oxygen production both at the oxycline and in the anoxic bottom layer. It is likely that this interaction between oxygenic phototrophs and aerobic methanotrophs represents a widespread mechanism by which methane is oxidized in lake water, thus diminishing its release into the atmosphere.

  16. Dependence of reaction rate of pyrite oxidation on temperature, pH and oxidant concentration

    Institute of Scientific and Technical Information of China (English)

    LU; Long; WANG; Rucheng; XUE; Jiyue; CHEN; Fanrong; CHEN; J

    2005-01-01

    The kinetic sstudy of pyrite oxidation was performed in a series of experiments by a mixed flow reactor. The release rates of Fe(II) are in the order of 3.22×10-9-5.51×10-7 mol·m-2·s-1 at temperature (T ) 25 to 44℃, initial pH (pH )1.4 to 2.7, and initial Fe(III) concentration ([Fe(III)]I) 10-5 to 5×10-3 mol·kg-1. The release rate of Fe(II) increased with increasing T or/and pH or/and [Fe(III)]I in the above range. The rate law and activation energy of pyrite oxidation were derived by statistical analyses of Rfe(II) vs. [Fe(III)]I, Rfe(II) vs. pH and Rfe(II) vs. T, and are given as (1) Rate law: Rfe(II)=104.65e-64.54×103/8.31T[Fe(III)]i0.6./[H+]0.45 ; (2) activation energy: 64.54 ( 8.07 kJ·mol-1. The expression can be applied to more cases (e.g., quantifying the pollutant released from sulfide-rich mining waste and assessing reliable performance of underground repository sites where pyrite acts as an engineered barrier material). Using the rate law derived from this study, the magnitude of the pollutants transferred to secondary phases, soil and water from oxidized pyrite during Jiguanshan mine waste weathering was preliminarily estimated. The estimated magnitude is very high, suggesting that the pile has possibly posed significant impact on the water quality in this region.

  17. Nitric oxide-dependent penile erection in mice lacking neuronal nitric oxide synthase.

    OpenAIRE

    Burnett, A. L.; Nelson, R.J.; Calvin, D. C.; Liu, J. X.; Demas, G E; Klein, S. L.; Kriegsfeld, L. J.; Dawson, V L; Dawson, T. M.; Snyder, S H

    1996-01-01

    BACKGROUND: Nitric oxide (NO) has been implicated as a mediator of penile erection, because the neuronal isoform of NO synthase (NOS) is localized to the penile innervation and NOS inhibitors selectively block erections. NO can also be formed by two other NOS isoforms derived from distinct genes, inducible NOS (iNOS) and endothelial NOS (eNOS). To clarify the source of NO in penile function, we have examined mice with targeted deletion of the nNOS gene (nNOS- mice). MATERIALS AND METHODS: Mat...

  18. Cyclic AMP-dependent phosphorylation of neuronal nitric oxide synthase mediates penile erection

    OpenAIRE

    Hurt, K. Joseph; Sezen, Sena F.; Lagoda, Gwen F.; Musicki, Biljana; Rameau, Gerald A.; Snyder, Solomon H.; Burnett, Arthur L.

    2012-01-01

    Nitric oxide (NO) generated by neuronal NO synthase (nNOS) initiates penile erection, but has not been thought to participate in the sustained erection required for normal sexual performance. We now show that cAMP-dependent phosphorylation of nNOS mediates erectile physiology, including sustained erection. nNOS is phosphorylated by cAMP-dependent protein kinase (PKA) at serine(S)1412. Electrical stimulation of the penile innervation increases S1412 phosphorylation that is blocked by PKA inhib...

  19. Oxidative Stress and Autophagy in the Regulation of Lysosome-Dependent Neuron Death

    OpenAIRE

    Pivtoraiko, Violetta N.; Stone, Sara L; Roth, Kevin A.; Shacka, John J

    2009-01-01

    Lysosomes critically regulate the pH-dependent catabolism of extracellular and intracellular macromolecules delivered from the endocytic/heterophagy and autophagy pathways, respectively. The importance of lysosomes to cell survival is underscored not only by their unique ability effectively to degrade metalloproteins and oxidatively damaged macromolecules, but also by the distinct potential for induction of both caspase-dependent and -independent cell death with a compromise in the integrity ...

  20. Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

    Directory of Open Access Journals (Sweden)

    Matthias Augustin

    2015-01-01

    Full Text Available Manganese oxides are one of the most important groups of materials in energy storage science. In order to fully leverage their application potential, precise control of their properties such as particle size, surface area and Mnx+ oxidation state is required. Here, Mn3O4 and Mn5O8 nanoparticles as well as mesoporous α-Mn2O3 particles were synthesized by calcination of Mn(II glycolate nanoparticles obtained through an economical route based on a polyol synthesis. The preparation of the different manganese oxides via one route facilitates assigning actual structure–property relationships. The oxidation process related to the different MnOx species was observed by in situ X-ray diffraction (XRD measurements showing time- and temperature-dependent phase transformations occurring during oxidation of the Mn(II glycolate precursor to α-Mn2O3 via Mn3O4 and Mn5O8 in O2 atmosphere. Detailed structural and morphological investigations using transmission electron microscopy (TEM and powder XRD revealed the dependence of the lattice constants and particle sizes of the MnOx species on the calcination temperature and the presence of an oxidizing or neutral atmosphere. Furthermore, to demonstrate the application potential of the synthesized MnOx species, we studied their catalytic activity for the oxygen reduction reaction in aprotic media. Linear sweep voltammetry revealed the best performance for the mesoporous α-Mn2O3 species.

  1. The Apparent Involvement of ANMEs in Mineral Dependent Methane Oxidation, as an Analog for Possible Martian Methanotrophy

    OpenAIRE

    Orphan, Victoria J.; House, Christopher H.; Beal, Emily J.

    2011-01-01

    On Earth, marine anaerobic methane oxidation (AOM) can be driven by the microbial reduction of sulfate, iron, and manganese. Here, we have further characterized marine sediment incubations to determine if the mineral dependent methane oxidation involves similar microorganisms to those found for sulfate-dependent methane oxidation. Through FISH and FISH-SIMS analyses using ^(13)C and ^(15)N labeled substrates, we find that the most active cells during manganese dependent AOM are...

  2. Sulfur globule oxidation in green sulfur bacteria is dependent on the dissimilatory sulfite reductase system

    DEFF Research Database (Denmark)

    Holkenbrink, Carina; Ocón Barbas, Santiago; Mellerup, Anders;

    2011-01-01

    Green sulfur bacteria oxidize sulfide and thiosulfate to sulfate with extracellular globules of elemental sulfur as intermediate. Here we investigated which genes are involved in the formation and consumption of these sulfur globules in the green sulfur bacterium Chlorobaculum tepidum. We show that...... sulfur globule oxidation is strictly dependent on the dissimilatory sulfite reductase (DSR) system. Deletion of dsrM/CT2244 or dsrT/CT2245 or the two dsrCABL clusters (CT0851-CT0854, CT2247-2250) abolished sulfur globule oxidation and prevented formation of sulfate from sulfide, whereas deletion of dsr......:quinone oxidoreductases (sqrB/CT0117 and sqrD/CT1087) were deleted, exhibited a decreased sulfide oxidation rate (~50% of wild type), yet formation and consumption of sulfur globules were not affected. The observation that mutants lacking the DSR system maintain efficient growth, suggests that the DSR system is...

  3. Nitric Oxide Signaling Depends on Biotin in Jurkat Human Lymphoma Cells12

    OpenAIRE

    Rodriguez-Melendez, Rocio; Zempleni, Janos

    2009-01-01

    Biotin affects gene expression through a diverse array of cell signaling pathways. Previous studies provided evidence that cGMP-dependent signaling also depends on biotin, but the mechanistic sequence of cGMP regulation by biotin is unknown. Here we tested the hypothesis that the effects of biotin in cGMP-dependent cell signaling are mediated by nitric oxide (NO). Human lymphoid (Jurkat) cells were cultured in media containing deficient (0.025 nmol/L), physiological (0.25 nmol/L), and pharmac...

  4. Grain size and burnup dependence of spent fuel oxidation: Geological repository impact

    International Nuclear Information System (INIS)

    Further refinements to the oxidation model of Stout et al. have been made. The present model incorporates the burnup dependence of the oxidation rate and an allowance for a distribution of grain sizes. The model was tested by comparing the model results with the oxidation histories of spent-fuel samples oxidized in thermogravimetric analysis (TGA) or oven dry-bath (ODB) experiments. The experimental and model results are remarkably close and confirm the assumption that grain-size distributions and activation energies are the important parameters to predicting oxidation behavior. The burnup dependence of the activation energy was shown to have a greater effect than decreasing the effective grain size in suppressing the rate of the reaction U4O9r↓U3O8. Model results predict that U3O8 formation of spent fuels exposed to oxygen will be suppressed even for high burnup fuels that have undergone restructuring in the rim region, provided the repository temperature is kept sufficiently low

  5. Mitochondrial isocitrate dehydrogenase is inactivated upon oxidation and reactivated by thioredoxin-dependent reduction in Arabidopsis

    Directory of Open Access Journals (Sweden)

    ToruHisabori

    2014-09-01

    Full Text Available Regulation of mitochondrial metabolism is essential for ensuring cellular growth and maintenance in plants. Based on redox-proteomics analysis, several proteins involved in diverse mitochondrial reactions have been identified as potential redox-regulated proteins. NAD+-dependent isocitrate dehydrogenase (IDH, a key enzyme in the tricarboxylic acid cycle, is one such candidate. In this study, we investigated the redox regulation mechanisms of IDH by biochemical procedures. In contrast to mammalian and yeast counterparts reported to date, recombinant IDH in Arabidopsis mitochondria did not show adenylate-dependent changes in enzymatic activity. Instead, IDH was inactivated by oxidation treatment and partially reactivated by subsequent reduction. Functional IDH forms a heterodimer comprising regulatory (IDH-r and catalytic (IDH-c subunits. IDH-r was determined to be the target of oxidative modifications forming an oligomer via intermolecular disulfide bonds. Mass spectrometric analysis combined with tryptic digestion of IDH-r indicated that Cys128 and Cys216 are involved in intermolecular disulfide bond formation. Furthermore, we showed that mitochondria-localized o-type thioredoxin (Trx-o promotes the reduction of oxidized IDH-r. These results suggest that IDH-r is susceptible to oxidative stress, and Trx-o serves to convert oxidized IDH-r to the reduced form that is necessary for active IDH complex.

  6. Structural and functional characteristics of cGMP-dependent methionine oxidation in Arabidopsis thaliana proteins

    KAUST Repository

    Marondedze, Claudius

    2013-01-05

    Background: Increasing structural and biochemical evidence suggests that post-translational methionine oxidation of proteins is not just a result of cellular damage but may provide the cell with information on the cellular oxidative status. In addition, oxidation of methionine residues in key regulatory proteins, such as calmodulin, does influence cellular homeostasis. Previous findings also indicate that oxidation of methionine residues in signaling molecules may have a role in stress responses since these specific structural modifications can in turn change biological activities of proteins. Findings. Here we use tandem mass spectrometry-based proteomics to show that treatment of Arabidopsis thaliana cells with a non-oxidative signaling molecule, the cell-permeant second messenger analogue, 8-bromo-3,5-cyclic guanosine monophosphate (8-Br-cGMP), results in a time-dependent increase in the content of oxidised methionine residues. Interestingly, the group of proteins affected by cGMP-dependent methionine oxidation is functionally enriched for stress response proteins. Furthermore, we also noted distinct signatures in the frequency of amino acids flanking oxidised and un-oxidised methionine residues on both the C- and N-terminus. Conclusions: Given both a structural and functional bias in methionine oxidation events in response to a signaling molecule, we propose that these are indicative of a specific role of such post-translational modifications in the direct or indirect regulation of cellular responses. The mechanisms that determine the specificity of the modifications remain to be elucidated. 2013 Marondedze et al.; licensee BioMed Central Ltd.

  7. Towards a Mechanistic Understanding of Anaerobic Nitrate Dependent Iron Oxidation: Balancing Electron Uptake and Detoxification

    Directory of Open Access Journals (Sweden)

    JohnDCoates

    2012-02-01

    Full Text Available The anaerobic oxidation of Fe(II by subsurface microorganisms is an important part of biogeochemical cycling in the environment, but the biochemical mechanisms used to couple iron oxidation to nitrate respiration are not well understood. Based on our own work and the evidence available in the literature, we propose a mechanistic model for anaerobic nitrate dependent iron oxidation. We suggest that anaerobic iron oxidizing microorganisms likely exist along a continuum including: 1 bacteria that inadvertently oxidize Fe(II by abiotic or biotic reactions with enzymes or chemical intermediates in their metabolic pathways (e.g. denitrification and suffer from toxicity or energetic penalty, 2 Fe(II tolerant bacteria that gain little or no growth benefit from iron oxidation but can manage the toxic reactions, and 3 bacteria that efficiently accept electrons from Fe(II to gain a growth advantage while preventing or mitigating the toxic reactions. Predictions of the proposed model are highlighted and experimental approaches are discussed.

  8. The oxidative costs of reproduction are group-size dependent in a wild cooperative breeder.

    Science.gov (United States)

    Cram, Dominic L; Blount, Jonathan D; Young, Andrew J

    2015-11-22

    Life-history theory assumes that reproduction entails a cost, and research on cooperatively breeding societies suggests that the cooperative sharing of workloads can reduce this cost. However, the physiological mechanisms that underpin both the costs of reproduction and the benefits of cooperation remain poorly understood. It has been hypothesized that reproductive costs may arise in part from oxidative stress, as reproductive investment may elevate exposure to reactive oxygen species, compromising survival and future reproduction and accelerating senescence. However, experimental evidence of oxidative costs of reproduction in the wild remains scarce. Here, we use a clutch-removal experiment to investigate the oxidative costs of reproduction in a wild cooperatively breeding bird, the white-browed sparrow weaver, Plocepasser mahali. Our results reveal costs of reproduction that are dependent on group size: relative to individuals in groups whose eggs were experimentally removed, individuals in groups that raised offspring experienced an associated cost (elevated oxidative damage and reduced body mass), but only if they were in small groups containing fewer or no helpers. Furthermore, during nestling provisioning, individuals that provisioned at higher rates showed greater within-individual declines in body mass and antioxidant protection. Our results provide rare experimental evidence that reproduction can negatively impact both oxidative status and body mass in the wild, and suggest that these costs can be mitigated in cooperative societies by the presence of additional helpers. These findings have implications for our understanding of the energetic and oxidative costs of reproduction, and the benefits of cooperation in animal societies. PMID:26582023

  9. Opposing effects of oxidative challenge and carotenoids on antioxidant status and condition-dependent sexual signalling.

    Science.gov (United States)

    Tomášek, Oldřich; Gabrielová, Barbora; Kačer, Petr; Maršík, Petr; Svobodová, Jana; Syslová, Kamila; Vinkler, Michal; Albrecht, Tomáš

    2016-01-01

    Several recent hypotheses consider oxidative stress to be a primary constraint ensuring honesty of condition-dependent carotenoid-based signalling. The key testable difference between these hypotheses is the assumed importance of carotenoids for redox homeostasis, with carotenoids being either antioxidant, pro-oxidant or unimportant. We tested the role of carotenoids in redox balance and sexual signalling by exposing adult male zebra finches (Taeniopygia guttata) to oxidative challenge (diquat dibromide) and manipulating carotenoid intake. As the current controversy over the importance of carotenoids as antioxidants could stem from the hydrophilic basis of commonly-used antioxidant assays, we used the novel measure of in vivo lipophilic antioxidant capacity. Oxidative challenge reduced beak pigmentation but elicited an increase in antioxidant capacity suggesting resource reallocation from signalling to redox homeostasis. Carotenoids counteracted the effect of oxidative challenge on lipophilic (but not hydrophilic) antioxidant capacity, thereby supporting carotenoid antioxidant function in vivo. This is inconsistent with hypotheses proposing that signalling honesty is maintained through either ROS-induced carotenoid degradation or the pro-oxidant effect of high levels of carotenoid-cleavage products acting as a physiological handicap. Our data further suggest that assessment of lipophilic antioxidant capacity is necessary to fully understand the role of redox processes in ecology and evolution. PMID:27000655

  10. Dose-dependent influence of genetic polymorphisms on DNA damage induced by styrene oxide, ethylene oxide and gamma-radiation

    International Nuclear Information System (INIS)

    Styrene oxide (SO), ethylene oxide (EO) and gamma-radiation (G) are agents with a well-described metabolism and genotoxicity. EPHX1 and GSTs play an important role in the detoxification of electrophiles and oxidative stress. Enzymes involved in base excision repair (hOGG1, XRCC1), in rejoining single strand breaks (XRCC1) and in repair of cross-links and chromosomal double strand breaks (XRCC3) might have an impact on genotoxicity as well. In this study we assessed the dose-dependent effect of genetic polymorphisms in biotransforming (EPHX (Tyr113/His113 and His139/Arg139), GSTP1 (Ile105/Val105), GSTM1 and GSTT1) and DNA repair enzymes (hOGG1 (Ser326/Cys326), XRCC1 (Arg194/Trp194, Arg28/His28, Arg399/Gln399), XRCC3 (Thr241/Met241)) on the induced genotoxicity. Peripheral blood mononuclear cells from 20 individuals were exposed to 3 doses per agent (+control). Genotoxicity was evaluated by measuring comet tail length (TL) and micronucleus frequencies in binucleated cells (MNCB). Dose-dependent DNA damage was found for all agents and end-points, with the exception of MNCB induced by EO. Repeated measure ANOVA revealed a significant contribution of hOGG1 and XRCC3 genotypes to the inter-individual variability of TL and MNCB in cells exposed to EO and G. Homozygous hOGG1 326 wild cells showed significantly lower EO-induced TL than the heterozygous cells. Significantly higher TL and MNCB were found in EO-exposed cells carrying the XRCC3 241Met variant and the influence on TL was more pronounced at higher dose. In G-irradiated cells, TL was significantly higher in the hOGG1 326 homozygous wild types compared with mutated genotypes. The influence of hOGG1 326 on TL was borderline dose-dependent. We conclude that the influence of genetic polymorphisms of enzymes involved in DNA repair on induced genotoxicity depends on exposure dose

  11. Oral sapropterin acutely augments reflex vasodilation in aged human skin through nitric oxide-dependent mechanisms

    OpenAIRE

    Stanhewicz, Anna E.; Alexander, Lacy M.; Kenney, W. Larry

    2013-01-01

    Functional constitutive nitric oxide synthase (NOS) and its cofactor tetrahydrobiopterin (BH4) are required for full reflex cutaneous vasodilation and are attenuated in primary aging. Acute, locally administered BH4 increases reflex vasodilation through NO-dependent mechanisms in aged skin. We hypothesized that oral sapropterin (Kuvan, shelf-stable pharmaceutical formulation of BH4) would augment reflex vasodilation in aged human skin during hyperthermia. Nine healthy human subjects (76 ± 1 y...

  12. Diversity and enrichment of nitrite-dependent anaerobic methane oxidizing bacteria from wastewater sludge

    OpenAIRE

    Luesken, Francisca A.; van Alen, Theo A.; van der Biezen, Erwin; Frijters, Carla; Toonen, Ger; Kampman, Christel; Hendrickx, Tim L. G.; Zeeman, Grietje; Temmink, Hardy; Strous, Marc; Op den Camp, Huub J. M.; Jetten, Mike S. M.

    2011-01-01

    Recently discovered microorganisms affiliated to the bacterial phylum NC10, named “Candidatus Methylomirabilis oxyfera”, perform nitrite-dependent anaerobic methane oxidation. These microorganisms could be important players in a novel way of anaerobic wastewater treatment where ammonium and residual dissolved methane might be removed at the expense of nitrate or nitrite. To find suitable inocula for reactor startup, ten selected wastewater treatment plants (WWTPs) located in The Netherlands w...

  13. Nitric Oxide-Dependent Oxidative Stress Induced Mitochondrial DNA Overproliferation and Deletion in the Context of Cancer and Alzheimer Disease

    Directory of Open Access Journals (Sweden)

    Gjumrakch Aliev

    2015-03-01

    using cytological techniques suggests that successful dysregulation of the cell cycle is also the hallmark of neoplasm; early mitochondrial dependent cell-cycle pathophysiology in AD may recruit oncogenic signal transduction mechanisms and hence, can be viewed as an abortive neoplastic transformation. The common features on the mitochondrial abnormality were seen on the brain during tumorigenesis and AD indicating that mitochondrial DNA overproliferation and/or deletion are the key initiating factors for development, maturation, and progression of neurodegeneration as well as tumor growth and/or metastases. Materials presented in this work indicate that the Nitric oxide- (NO- dependent oxidative stress results in mitochondrial ultrastructural alterations and DNA damage in cases of Alzheimer disease (AD. However, little is known about these pathways in human cancers, especially during the development as well as the progression of primary brain tumors and metastatic colorectal cancer. One of the key features of tumors is the deficiency in tissue energy that accompanies mitochondrial lesions and formation of the hypoxic smaller sized mitochondria with ultrastructural abnormalities. We theorize that mitochondrial involvement may play a significant role in the etiopathogenesis of cancer. Moreover, our study also demonstrates a potential link between AD and cancer, and anticancer drugs are being explored for the inhibition of AD-like pathology in transgenic mice. Severity of the cancer growth, metastasis, and brain pathology in AD (in animal models that mimic human AD correlate with the degree of mitochondrial ultrastructural abnormalities. Recent advances in the cell-cycle reentry of the terminally differentiated neuronal cells indicate that NO-dependent mitochondrial abnormal activities and mitotic cell division are not the only important pathogenic factors in pathogenesis of cancer and AD, but open a new window for the development of novel treatment strategies for these

  14. Concentration dependent effect of calcium on brain mitochondrial bioenergetics and oxidative stress parameters

    Directory of Open Access Journals (Sweden)

    Patrick G Sullivan

    2013-12-01

    Full Text Available Mitochondrial dysfunction following traumatic brain and spinal cord injury (TBI and SCI plays a pivotal role in the development of secondary pathophysiology and subsequent neuronal cell death. Previously, we demonstrated a loss of mitochondrial bioenergetics in the first 24 h following TBI and SCI initiates a rapid and extensive necrotic event at the primary site of injury. Within the mitochondrial derived mechanisms, the cross talk and imbalance amongst the processes of excitotoxicity, Ca2+ cycling/overload, ATP synthesis, free radical production, and oxidative stress damage ultimately leading to mitochondrial damage followed by neuronal cell death and loss of behaviors. Mitochondria are one of the most important organelles that regulate for intracellular calcium (Ca2+ homeostasis; and are equipped with a tightly regulated Ca2+ transport system. However, owing to the lack of consensus and the link between the downstream effects of calcium in published literature, we undertook a systematic in vitro study for measuring concentration dependent effects of calcium (100-1000 nmols/mg mitochondrial protein on mitochondrial respiration, enzyme activities, reactive oxygen/nitrogen species (ROS/RNS generation, membrane potential (∆Ψ and oxidative damage markers in isolated brain mitochondria. We observed a dose- and time-dependent inhibition of mitochondrial respiration by calcium without influencing mitochondrial pyruvate dehydrogenase complex (PDHC and NADH dehydrogenase (Complex I enzyme activities. We observed dose-dependent decreased production of hydrogen peroxide and total ROS/RNS species generation by calcium and no significant changes in protein and lipid oxidative damage markers. These results may shed new light on the prevailing dogma of the direct effects of calcium on mitochondrial bioenergetics, free radical production and oxidative stress parameters that are primary regulatory mitochondrial mechanisms following neuronal injury.

  15. Genome-enabled studies of anaerobic, nitrate-dependent iron oxidation in the chemolithoautotrophic bacterium Thiobacillus denitrificans

    Directory of Open Access Journals (Sweden)

    Harry R Beller

    2013-08-01

    Full Text Available Thiobacillus denitrificans is a chemolithoautotrophic bacterium capable of anaerobic, nitrate-dependent U(IV and Fe(II oxidation, both of which can strongly influence the long-term efficacy of in situ reductive immobilization of uranium in contaminated aquifers. We previously identified two c-type cytochromes involved in nitrate-dependent U(IV oxidation in T. denitrificans and hypothesized that c-type cytochromes would also catalyze Fe(II oxidation, as they have been found to play this role in anaerobic phototrophic Fe(II-oxidizing bacteria. Here we report on efforts to identify genes associated with nitrate-dependent Fe(II oxidation, namely (a whole-genome transcriptional studies [using FeCO3, Fe2+, and U(IV oxides as electron donors under denitrifying conditions], (b Fe(II oxidation assays performed with knockout mutants targeting primarily highly expressed or upregulated c-type cytochromes, and (c random transposon-mutagenesis studies with screening for Fe(II oxidation. Assays of mutants for 26 target genes, most of which were c-type cytochromes, indicated that none of the mutants tested were significantly defective in nitrate-dependent Fe(II oxidation. The non-defective mutants included the c1-cytochrome subunit of the cytochrome bc1 complex (complex III, which has relevance to a previously proposed role for this complex in nitrate-dependent Fe(II oxidation and to current concepts of reverse electron transfer. A transposon mutant with a disrupted gene associated with NADH:ubiquinone oxidoreductase (complex I was ~35% defective relative to the wild-type strain; this strain was similarly defective in nitrate reduction with thiosulfate as the electron donor. Overall, our results indicate that nitrate-dependent Fe(II oxidation in T. denitrificans is not catalyzed by the same c-type cytochromes involved in U(IV oxidation, nor have other c-type cytochromes yet been implicated in the process.

  16. A Reactive Oxide Overlayer on Rh Nanoparticles during CO Oxidation and Its Size Dependence Studied by in Situ Ambient Pressure XPS

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Michael E.; Zhang, Yawen; Butcher, Derek R.; Park, Jeong Y.; Li, Yimin; Bluhm, Hendrik; Bratlie, Kaitlin M.; Zhang, Tianfu; Somorjai, Gabor A.

    2008-09-15

    CO oxidation is one of the most studied heterogeneous reactions, being scientifically and industrially important, particularly for removal of CO from exhaust streams and preferential oxidation for hydrogen purification in fuel cell applications. The precious metals Ru, Rh, Pd, Pt, and Au are most commonly used for this reaction because of their high activity and stability. Despite the wealth of experimental and theoretical data, it remains unclear what is the active surface for CO oxidation under catalytic conditions for these metals. In this communication, we utilize in situ synchrotron ambient pressure X-ray photoelectron spectroscopy (APXPS) to monitor the oxidation state at the surface of Rh nanoparticles during CO oxidation and demonstrate that the active catalyst is a surface oxide, the formation of which is dependent on particle size. The amount of oxide formed and the reaction rate both increase with decreasing particle size.

  17. Shape-Dependent Activity of Ceria for Hydrogen Electro-Oxidation in Reduced-Temperature Solid Oxide Fuel Cells.

    Science.gov (United States)

    Tong, Xiaofeng; Luo, Ting; Meng, Xie; Wu, Hao; Li, Junliang; Liu, Xuejiao; Ji, Xiaona; Wang, Jianqiang; Chen, Chusheng; Zhan, Zhongliang

    2015-11-01

    Single crystalline ceria nanooctahedra, nanocubes, and nanorods are hydrothermally synthesized, colloidally impregnated into the porous La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) scaffolds, and electrochemically evaluated as the anode catalysts for reduced temperature solid oxide fuel cells (SOFCs). Well-defined surface terminations are confirmed by the high-resolution transmission electron microscopy--(111) for nanooctahedra, (100) for nanocubes, and both (110) and (100) for nanorods. Temperature-programmed reduction in H2 shows the highest reducibility for nanorods, followed sequentially by nanocubes and nanooctahedra. Measurements of the anode polarization resistances and the fuel cell power densities reveal different orders of activity of ceria nanocrystals at high and low temperatures for hydrogen electro-oxidation, i.e., nanorods > nanocubes > nanooctahedra at T ≤ 450 °C and nanooctahedra > nanorods > nanocubes at T ≥ 500 °C. Such shape-dependent activities of these ceria nanocrystals have been correlated to their difference in the local structure distortions and thus in the reducibility. These findings will open up a new strategy for design of advanced catalysts for reduced-temperature SOFCs by elaborately engineering the shape of nanocrystals and thus selectively exposing the crystal facets. PMID:26307555

  18. Keap1 redox-dependent regulation of doxorubicin-induced oxidative stress response in cardiac myoblasts

    International Nuclear Information System (INIS)

    Doxorubicin (DOX) is a widely prescribed treatment for a broad scope of cancers, but clinical utility is limited by the cumulative, dose-dependent cardiomyopathy that occurs with repeated administration. DOX-induced cardiotoxicity is associated with the production of reactive oxygen species (ROS) and oxidation of lipids, DNA and proteins. A major cellular defense mechanism against such oxidative stress is activation of the Keap1/Nrf2-antioxidant response element (ARE) signaling pathway, which transcriptionally regulates expression of antioxidant genes such as Nqo1 and Gstp1. In the present study, we address the hypothesis that an initial event associated with DOX-induced oxidative stress is activation of the Keap1/Nrf2-dependent expression of antioxidant genes and that this is regulated through drug-induced changes in redox status of the Keap1 protein. Incubation of H9c2 rat cardiac myoblasts with DOX resulted in a time- and dose-dependent decrease in non-protein sulfhydryl groups. Associated with this was a near 2-fold increase in Nrf2 protein content and enhanced transcription of several of the Nrf2-regulated down-stream genes, including Gstp1, Ugt1a1, and Nqo1; the expression of Nfe2l2 (Nrf2) itself was unaltered. Furthermore, both the redox status and the total amount of Keap1 protein were significantly decreased by DOX, with the loss of Keap1 being due to both inhibited gene expression and increased autophagic, but not proteasomal, degradation. These findings identify the Keap1/Nrf2 pathway as a potentially important initial response to acute DOX-induced oxidative injury, with the primary regulatory events being the oxidation and autophagic degradation of the redox sensor Keap1 protein. - Highlights: • DOX caused a ∼2-fold increase in Nrf2 protein content. • DOX enhanced transcription of several Nrf2-regulated down-stream genes. • Redox status and total amount of Keap1 protein were significantly decreased by DOX. • Loss of Keap1 protein was due to

  19. Keap1 redox-dependent regulation of doxorubicin-induced oxidative stress response in cardiac myoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Nordgren, Kendra K.S., E-mail: knordgre@d.umn.edu; Wallace, Kendall B., E-mail: kwallace@d.umn.edu

    2014-01-01

    Doxorubicin (DOX) is a widely prescribed treatment for a broad scope of cancers, but clinical utility is limited by the cumulative, dose-dependent cardiomyopathy that occurs with repeated administration. DOX-induced cardiotoxicity is associated with the production of reactive oxygen species (ROS) and oxidation of lipids, DNA and proteins. A major cellular defense mechanism against such oxidative stress is activation of the Keap1/Nrf2-antioxidant response element (ARE) signaling pathway, which transcriptionally regulates expression of antioxidant genes such as Nqo1 and Gstp1. In the present study, we address the hypothesis that an initial event associated with DOX-induced oxidative stress is activation of the Keap1/Nrf2-dependent expression of antioxidant genes and that this is regulated through drug-induced changes in redox status of the Keap1 protein. Incubation of H9c2 rat cardiac myoblasts with DOX resulted in a time- and dose-dependent decrease in non-protein sulfhydryl groups. Associated with this was a near 2-fold increase in Nrf2 protein content and enhanced transcription of several of the Nrf2-regulated down-stream genes, including Gstp1, Ugt1a1, and Nqo1; the expression of Nfe2l2 (Nrf2) itself was unaltered. Furthermore, both the redox status and the total amount of Keap1 protein were significantly decreased by DOX, with the loss of Keap1 being due to both inhibited gene expression and increased autophagic, but not proteasomal, degradation. These findings identify the Keap1/Nrf2 pathway as a potentially important initial response to acute DOX-induced oxidative injury, with the primary regulatory events being the oxidation and autophagic degradation of the redox sensor Keap1 protein. - Highlights: • DOX caused a ∼2-fold increase in Nrf2 protein content. • DOX enhanced transcription of several Nrf2-regulated down-stream genes. • Redox status and total amount of Keap1 protein were significantly decreased by DOX. • Loss of Keap1 protein was due to

  20. Dependence of the specific surface area of the nuclear fuel with the matrix oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, F.; Quinones, J.; Iglesias, E.; Rodriguez, N. [CIEMAT. Avda. Complutense 22, 28040-Madrid (Spain)

    2008-07-01

    This paper is focused on the study of the changes in the specific surface area measured using BET techniques. The objective is to obtain a relation between this parameter and the change in the matrix stoichiometry (i.e., oxidation increase). None of the actual models used for extrapolating the behaviour of the spent fuel matrix under repository conditions have included this dependence yet. In this work the specific surface area of different uranium oxide were measured using N{sub 2}(g) and Kr(g). The starting material was UO{sub 2+x}(s) with a size powder distribution lower than 20 {mu}m. The results included in this paper shown a strong dependence on specific surface area with the matrix stoichiometry, i.e., and increase of more than one order of magnitude (SUO{sub 2} = 6 m{sup 2}*g{sup -1} and SU{sub 3}O{sub 8} = 16.07 m{sup 2}*g{sup -1}). Furthermore, the particle size distribution measured as a function of the thermal treatment done shows changes on the powder size related to the changes observed in the uranium oxide stoichiometry. (authors)

  1. Dependence of the specific surface area of the nuclear fuel with the matrix oxidation

    International Nuclear Information System (INIS)

    This paper is focused on the study of the changes in the specific surface area measured using BET techniques. The objective is to obtain a relation between this parameter and the change in the matrix stoichiometry (i.e., oxidation increase). None of the actual models used for extrapolating the behaviour of the spent fuel matrix under repository conditions have included this dependence yet. In this work the specific surface area of different uranium oxide were measured using N2(g) and Kr(g). The starting material was UO2+x(s) with a size powder distribution lower than 20 μm. The results included in this paper shown a strong dependence on specific surface area with the matrix stoichiometry, i.e., and increase of more than one order of magnitude (SUO2 = 6 m2*g-1 and SU3O8 = 16.07 m2*g-1). Furthermore, the particle size distribution measured as a function of the thermal treatment done shows changes on the powder size related to the changes observed in the uranium oxide stoichiometry. (authors)

  2. Temperature dependence studies on the electro-oxidation of aliphatic alcohols with modified platinum electrodes

    Indian Academy of Sciences (India)

    Panadda Katikawong; Tanakorn Ratana; Waret Veerasai

    2009-05-01

    Temperature dependence on the electro-oxidation of methanol, ethanol and 1-propanol in 0.5 M H2SO4 were investigated with Pt and PtRu electrodes. Tafel slope and apparent activation energy were evaluated from the cyclic voltammetric data in the low potential region (0.3-0.5 V vs SHE). The CV results provided Tafel slopes for alcohols in the range of 200-400 mV dec-1 which indicated a difference in the rate determining step. The decrease in Tafel slope was only observed in the case of methanol for the Ru-modified Pt electrode. This indicates that Ru improves the rate of determining step for methanol while hindering it for the other alcohols. The electrochemical impedance spectroscopy was also used to evaluate the electro-oxidation mechanism of alcohols on these electrodes. The simulated EIS results provided two important parameters: charge transfer resistance () and inductance (). The $R^{-1}_{ct}$ and -1 represent the rate of alcohol electro-oxidation and rate of desorption of intermediate species, respectively. These values increased with the increasing of temperature. The results from two techniques were well agreed that the electro-oxidation of methanol was improved by raising the temperature and ruthenium modification.

  3. DJ-1-dependent regulation of oxidative stress in the retinal pigment epithelium (RPE.

    Directory of Open Access Journals (Sweden)

    Karen G Shadrach

    Full Text Available BACKGROUND: DJ-1 is found in many tissues, including the brain, where it has been extensively studied due to its association with Parkinson's disease. DJ-1 functions as a redox-sensitive molecular chaperone and transcription regulator that robustly protects cells from oxidative stress. METHODOLOGY: Retinal pigment epithelial (RPE cultures were treated with H2O2 for various times followed by biochemical and immunohistological analysis. Cells were transfected with adenoviruses carrying the full-length human DJ-1 cDNA and a mutant construct, which has the cysteine residues at amino acid 46, 53 and 106 mutated to serine (C to S prior to stress experiments. DJ-1 localization, levels of expression and reactive oxygen species (ROS generation were also analyzed in cells expressing exogenous DJ-1 under baseline and oxidative stress conditions. The presence of DJ-1 and oxidized DJ-1 was evaluated in human RPE total lysates. The distribution of DJ-1 was assessed in AMD and non-AMD cryosectionss and in isolated human Bruch's membrane (BM/choroid from AMD eyes. PRINCIPAL FINDINGS: DJ-1 in RPE cells under baseline conditions, displays a diffuse cytoplasmic and nuclear staining. After oxidative challenge, more DJ-1 was associated with mitochondria. Increasing concentrations of H2O2 resulted in a dose-dependent increase in DJ-1. Overexpression of DJ-1 but not the C to S mutant prior to exposure to oxidative stress led to significant decrease in the generation of ROS. DJ-1 and oxDJ-1 intensity of immunoreactivity was significantly higher in the RPE lysates from AMD eyes. More DJ-1 was localized to RPE cells from AMD donors with geographic atrophy and DJ-1 was also present in isolated human BM/choroid from AMD eyes. CONCLUSIONS/SIGNIFICANCE: DJ-1 regulates RPE responses to oxidative stress. Most importantly, increased DJ-1 expression prior to oxidative stress leads to decreased generation of ROS, which will be relevant for future studies of AMD since oxidative

  4. Temperature-dependent minority carrier lifetime of crystalline silicon wafers passivated by high quality amorphous silicon oxide

    Science.gov (United States)

    Inaba, Masahiro; Todoroki, Soichiro; Nakada, Kazuyoshi; Miyajima, Shinsuke

    2016-04-01

    We investigated the effects of annealing on the temperature-dependent minority carrier lifetime of a crystalline silicon wafer passivated by hydrogenated amorphous silicon oxide. The annealing significantly affects the lifetime and its temperature dependence. Our device simulations clearly indicate that valence band offset significantly affects the temperature dependence. We also found a slight increase in the interface defect density after annealing.

  5. Voltage-Dependent Electronic Transport Properties of Reduced Graphene Oxide with Various Coverage Ratios

    Institute of Scientific and Technical Information of China (English)

    Serhan Yamacli

    2015-01-01

    Graphene is mainly implemented by these methods: exfoliating, unzipping of carbon nanotubes, chemical vapour deposition, epitaxial growth and the reduction of graphene oxide. The latter option has the advantage of low cost and precision. However, reduced graphene oxide (rGO) contains hydrogen and/or oxygen atoms hence the structure and properties of the rGO and intrinsic graphene are different. Considering the advantages of the implementation and utili-zation of rGO, voltage-dependent electronic transport properties of several rGO samples with various coverage ratios are investigated in this work. Ab initio simulations based on density functional theory combined with non-equilibrium Green’s function formalism are used to obtain the current–voltage characteristics and the voltage-dependent transmission spectra of rGO samples. It is shown that the transport properties of rGO are strongly dependent on the coverage ratio. Obtained results indicate that some of the rGO samples have negative differential resistance characteristics while normally insulating rGO can behave as conducting beyond a certain threshold voltage. The reasons of the peculiar electronic transport behaviour of rGO samples are further investigated, taking the transmission eigenstates and their localization degree into consideration. The findings of this study are expected to be helpful for engineering the characteristics of rGO structures.

  6. Cytochrome P-450 dependent ethanol oxidation. Kinetic isotope effects and absence of stereoselectivity

    International Nuclear Information System (INIS)

    Deuterium isotope effects [/sup D/(V/K)] and stereoselectivity of ethanol oxidation in cytochrome P-450 containing systems and in the xanthine-xanthine oxidase system were compared with those of yeast alcohol dehydrogenase. The isotope effects were determined by using both a noncompetitive method, including incubation of unlabeled of [1,1-2H2] ethanol at various concentrations, and a competitive method, where 1:1 mixtures of [1-13C]- and [2H6] ethanol or [2,2,2-2H3]- and [1,1-2H2] ethanol were incubated and the acetaldehyde formed was analyzed by gas chromatography/mass spectrometry. The /sup D/(V/K) isotope effects of the cytochrome P-450 dependent ethanol oxidation were about 4 with liver microsomes from imidazole-, phenobarbital- or acetone-treated rabbits or with microsomes from acetone- or ethanol-treated rats. Similar isotope effects were reached with reconstituted membranes containing the rabbit ethanol-inducible cytochrome P-450 (LMeb), whereas control rat microsomes and membranes containing rabbit phenobarbital-inducible P-450 LM2 oxidized the alcohol with /sup D/(V/K) of about 2.8 and 1.8, respectively. Addition of Fe/sup III/EDTA either to microsomes from phenobarbital-treated rabbits or to membranes containing P-450 LMeb significantly lowered the isotope effect. Incubations of all cytochrome P-450 containing systems of the xanthine-xanthine oxidase systems with (1R)- and (1S)-[1-2H] ethanol, revealed, taking the isotope effects into account, that 44-66% of the ethanol oxidized had lost the 1-pro-R hydrogen. The data indicate that cytochrome P-450 dependent ethanol oxidation is not stereospecific and that cleavage of the C1-H bond appears to be a rate-determining step in the catalysis by the ethanol-inducible form of P-450. The contribution of hydroxyl radicals in ethanol oxidation by the various enzymic systems is discussed

  7. Postischemic vasodilation in human forearm is dependent on endothelium-derived nitric oxide.

    Science.gov (United States)

    Meredith, I T; Currie, K E; Anderson, T J; Roddy, M A; Ganz, P; Creager, M A

    1996-04-01

    Although endothelium-derived nitric oxide contributes to basal vascular tone, little is known about its role in regulating blood flow during changes in metabolic supply and demand. We examined the contribution of endothelium-derived nitric oxide to reactive hyperemia in the forearm of 20 normal subjects (12 women, 8 men) aged 27 +/- 4 yr (means +/- SD), using the nitric oxide synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA). Forearm ischemia was induced by suprasystolic blood pressure cuff inflation for 5 min, and the subsequent hyperemic flow was recorded for 5 min using venous occlusion strain-gauge plethysmography. The efficacy of nitric oxide blockade was tested by comparing the dose-response relationship to the endothelium-dependent agonist, acetylcholine (3, 10, and 30 mg/min), before and after intra-arterial infusion of up to 2,000 mg/min of L-NMMA. L-NMMA produced a significant downward and rightward shift in the dose-response relationship to acetylcholine and a 39% reduction in response to the maximum dose (P curve, at 1 and 5 min after cuff release was 17 and 23% less, respectively (13.6 +/- 1.2 vs. 11.3 +/- 1.1 and 31.8 +/- 2.7 vs. 24.6 +/- 1.8 ml/100 ml, P < 0.002), following L-NMMA. These data suggest that endothelium-derived nitric oxide plays a role in both reactive hyperemia and in the maintenance of the hyperemic response following ischemia in the forearm. PMID:8967386

  8. Trifluorosubstrates as mechanistic probes for an FMN-dependent l-2-hydroxy acid-oxidizing enzyme.

    Science.gov (United States)

    Lederer, Florence; Vignaud, Caroline; North, Paul; Bodevin, Sabrina

    2016-09-01

    A controversy exists with respect to the mechanism of l-2-hydroxy acid oxidation by members of a family of FMN-dependent enzymes. A so-called carbanion mechanism was initially proposed, in which the active site histidine abstracts the substrate α-hydrogen as a proton, followed by electron transfer from the carbanion to the flavin. But an alternative mechanism was not incompatible with some results, a mechanism in which the active site histidine instead picks up the substrate hydroxyl proton and a hydride transfer occurs. Even though more recent experiments ruling out such a mechanism were published (Rao & Lederer (1999) Protein Science 7, 1531-1537), a few authors have subsequently interpreted their results with variant enzymes in terms of a hydride transfer. In the present work, we analyse the reactivity of trifluorolactate, a substrate analogue, with the flavocytochrome b2 (Fcb2) flavodehydrogenase domain, compared to its reactivity with an NAD-dependent lactate dehydrogenase (LDH), for which this compound is known to be an inhibitor (Pogolotti & Rupley (1973) Biochem. Biophys. Res. Commun, 55, 1214-1219). Indeed, electron attraction by the three fluorine atoms should make difficult the removal of the α-H as a hydride. We also analyse the reactivity of trifluoropyruvate with the FMN- and NAD-dependent enzymes. The results substantiate a different effect of the fluorine substituents on the two enzymes compared to their normal substrates. In the discussion we analyse the conclusions of recent papers advocating a hydride transfer mechanism for the family of l-2-hydroxy acid oxidizing FMN-dependent enzymes. PMID:27155230

  9. Size dependent microbial oxidation and reduction of magnetite nano- and micro-particles

    Science.gov (United States)

    Byrne, James M.; van der Laan, Gerrit; Figueroa, Adriana I.; Qafoku, Odeta; Wang, Chongmin; Pearce, Carolyn I.; Jackson, Michael; Feinberg, Joshua; Rosso, Kevin M.; Kappler, Andreas

    2016-08-01

    The ability for magnetite to act as a recyclable electron donor and acceptor for Fe-metabolizing bacteria has recently been shown. However, it remains poorly understood whether microbe-mineral interfacial electron transfer processes are limited by the redox capacity of the magnetite surface or that of whole particles. Here we examine this issue for the phototrophic Fe(II)-oxidizing bacteria Rhodopseudomonas palustris TIE-1 and the Fe(III)-reducing bacteria Geobacter sulfurreducens, comparing magnetite nanoparticles (d ≈ 12 nm) against microparticles (d ≈ 100–200 nm). By integrating surface-sensitive and bulk-sensitive measurement techniques we observed a particle surface that was enriched in Fe(II) with respect to a more oxidized core. This enables microbial Fe(II) oxidation to occur relatively easily at the surface of the mineral suggesting that the electron transfer is dependent upon particle size. However, microbial Fe(III) reduction proceeds via conduction of electrons into the particle interior, i.e. it can be considered as more of a bulk electron transfer process that is independent of particle size. The finding has potential implications on the ability of magnetite to be used for long range electron transport in soils and sediments.

  10. Hodgkin and Reed-Sternberg cells of classical Hodgkin lymphoma are highly dependent on oxidative phosphorylation.

    Science.gov (United States)

    Birkenmeier, Katrin; Dröse, Stefan; Wittig, Ilka; Winkelmann, Ria; Käfer, Viktoria; Döring, Claudia; Hartmann, Sylvia; Wenz, Tina; Reichert, Andreas S; Brandt, Ulrich; Hansmann, Martin-Leo

    2016-05-01

    The metabolic properties of lymphomas derived from germinal center (GC) B cells have important implications for therapeutic strategies. In this study, we have compared metabolic features of Hodgkin-Reed-Sternberg (HRS) cells, the tumor cells of classical Hodgkin's lymphoma (cHL), one of the most frequent (post-)GC-derived B-cell lymphomas, with their normal GC B cell counterparts. We found that the ratio of oxidative to nonoxidative energy conversion was clearly shifted toward oxidative phosphorylation (OXPHOS)-linked ATP synthesis in HRS cells as compared to GC B cells. Mitochondrial mass, the expression of numerous key proteins of oxidative metabolism and markers of mitochondrial biogenesis were markedly upregulated in cHL cell lines and in primary cHL cases. NFkappaB promoted this shift to OXPHOS. Functional analysis indicated that both cell growth and viability of HRS cells depended on OXPHOS. The high rates of OXPHOS correlated with an almost complete lack of lactate production in HRS cells not observed in other GC B-cell lymphoma cell lines. Overall, we conclude that OXPHOS dominates energy conversion in HRS cells, while nonoxidative ATP production plays a subordinate role. Our results suggest that OXPHOS could be a new therapeutic target and may provide an avenue toward new treatment strategies in cHL. PMID:26595876

  11. Regulatory mechanism of the flavoprotein Tah18-dependent nitric oxide synthesis and cell death in yeast.

    Science.gov (United States)

    Yoshikawa, Yuki; Nasuno, Ryo; Kawahara, Nobuhiro; Nishimura, Akira; Watanabe, Daisuke; Takagi, Hiroshi

    2016-07-01

    Nitric oxide (NO) is a ubiquitous signaling molecule involved in the regulation of a large number of cellular functions. The regulatory mechanism of NO generation in unicellular eukaryotic yeast cells is poorly understood due to the lack of mammalian and bacterial NO synthase (NOS) orthologues, even though yeast produces NO under oxidative stress conditions. Recently, we reported that the flavoprotein Tah18, which was previously shown to transfer electrons to the iron-sulfur cluster protein Dre2, is involved in NOS-like activity in the yeast Saccharomyces cerevisiae. On the other hand, Tah18 was reported to promote apoptotic cell death after exposure to hydrogen peroxide (H2O2). Here, we showed that NOS-like activity requiring Tah18 induced cell death upon treatment with H2O2. Our experimental results also indicate that Tah18-dependent NO production and cell death are suppressed by enhancement of the interaction between Tah18 and its molecular partner Dre2. Our findings indicate that the Tah18-Dre2 complex regulates cell death as a molecular switch via Tah18-dependent NOS-like activity in response to environmental changes. PMID:27178802

  12. Myeloperoxidase-dependent lipid peroxidation promotes the oxidative modification of cytosolic proteins in phagocytic neutrophils.

    Science.gov (United States)

    Wilkie-Grantham, Rachel P; Magon, Nicholas J; Harwood, D Tim; Kettle, Anthony J; Vissers, Margreet C; Winterbourn, Christine C; Hampton, Mark B

    2015-04-10

    Phagocytic neutrophils generate reactive oxygen species to kill microbes. Oxidant generation occurs within an intracellular phagosome, but diffusible species can react with the neutrophil and surrounding tissue. To investigate the extent of oxidative modification, we assessed the carbonylation of cytosolic proteins in phagocytic neutrophils. A 4-fold increase in protein carbonylation was measured within 15 min of initiating phagocytosis. Carbonylation was dependent on NADPH oxidase and myeloperoxidase activity and was inhibited by butylated hydroxytoluene and Trolox, indicating a role for myeloperoxidase-dependent lipid peroxidation. Proteomic analysis of target proteins revealed significant carbonylation of the S100A9 subunit of calprotectin, a truncated form of Hsp70, actin, and hemoglobin from contaminating erythrocytes. The addition of the reactive aldehyde 4-hydroxynonenal (HNE) caused carbonylation, and HNE-glutathione adducts were detected in the cytosol of phagocytic neutrophils. The post-translational modification of neutrophil proteins will influence the functioning and fate of these immune cells in the period following phagocytic activation, and provides a marker of neutrophil activation during infection and inflammation. PMID:25697357

  13. Flow-dependent regulation of endothelial nitric oxide synthase: role of protein kinases

    Science.gov (United States)

    Boo, Yong Chool; Jo, Hanjoong

    2003-01-01

    Vascular endothelial cells are directly and continuously exposed to fluid shear stress generated by blood flow. Shear stress regulates endothelial structure and function by controlling expression of mechanosensitive genes and production of vasoactive factors such as nitric oxide (NO). Though it is well known that shear stress stimulates NO production from endothelial nitric oxide synthase (eNOS), the underlying molecular mechanisms remain unclear and controversial. Shear-induced production of NO involves Ca2+/calmodulin-independent mechanisms, including phosphorylation of eNOS at several sites and its interaction with other proteins, including caveolin and heat shock protein-90. There have been conflicting results as to which protein kinases-protein kinase A, protein kinase B (Akt), other Ser/Thr protein kinases, or tyrosine kinases-are responsible for shear-dependent eNOS regulation. The functional significance of each phosphorylation site is still unclear. We have attempted to summarize the current status of understanding in shear-dependent eNOS regulation.

  14. Hydrogen sulfide increases nitric oxide production from endothelial cells by an Akt-dependent mechanism

    Directory of Open Access Journals (Sweden)

    ArturoJCardounel

    2011-12-01

    Full Text Available Hydrogen sulfide (H2S and nitric oxide (NO are both gasotransmitters that can elicit synergistic vasodilatory responses in the in the cardiovascular system, but the mechanisms behind this synergy are unclear. In the current study we investigated the molecular mechanisms through which H2S regulates endothelial NO production. Initial studies were performed to establish the temporal and dose-dependent effects of H2S on NO generation using EPR spin trapping techniques. H2S stimulated a two-fold increase in NO production from endothelial nitric oxide synthase (eNOS, which was maximal 30 min after exposure to 25-150 µM H2S. Following 30 min H2S exposure, eNOS phosphorylation at Ser 1177 was significantly increased compared to control, consistent with eNOS activation. Pharmacological inhibition of Akt, the kinase responsible for Ser 1177 phosphorylation, attenuated the stimulatory effect of H2S on NO production. Taken together, these data demonstrate that H2S up-regulates NO production from eNOS through an Akt-dependent mechanism. These results implicate H2S in the regulation of NO in endothelial cells, and suggest that deficiencies in H2S signaling can directly impact processes regulated by NO.

  15. Time dependent physiological characterization of yeast oxidative stress response and growth modulation of protein kinase/phosphatase mutants

    DEFF Research Database (Denmark)

    Altintas, Ali; Workman, Christopher

    mutants were selected for their known activities in various stress response pathways, including oxidative stress, and were investigated for their response to oxidative stress. Hydrogen peroxide was us ed as the oxidizing agent at a number of different concentrations ranging from mild to moderate stress (0......The objective of the project was to investigate the time-dependent batch growth effects of oxidative environmental conditions on protein ki nase (PK) and phosphatase (PP) deletion mutants and relevant wild type strains of Saccharomyces cerevisiae . To achieve this goal, 44 different PK and PP...

  16. Genome-Enabled Studies of Anaerobic, Nitrate-Dependent Iron Oxidation in the Chemolithoautotrophic Bacterium Thiobacillus denitrificans

    Science.gov (United States)

    Beller, H. R.; Zhou, P.; Legler, T. C.; Chakicherla, A.; O'Day, P. A.

    2013-12-01

    Thiobacillus denitrificans is a chemolithoautotrophic bacterium capable of anaerobic, nitrate-dependent U(IV) and Fe(II) oxidation, both of which can strongly influence the long-term efficacy of in situ reductive immobilization of uranium in contaminated aquifers. We previously identified two c-type cytochromes involved in nitrate-dependent U(IV) oxidation in T. denitrificans and hypothesized that c-type cytochromes would also catalyze Fe(II) oxidation, as they have been found to play this role in anaerobic phototrophic Fe(II)-oxidizing bacteria. Here we report on efforts to identify genes associated with nitrate-dependent Fe(II) oxidation, namely (a) whole-genome transcriptional studies [using FeCO3, Fe2+, and U(IV) oxides as electron donors under denitrifying conditions], (b) Fe(II) oxidation assays performed with knockout mutants targeting primarily highly expressed or upregulated c-type cytochromes, and (c) random transposon-mutagenesis studies with screening for Fe(II) oxidation. Assays of mutants for 26 target genes, most of which were c-type cytochromes, indicated that none of the mutants tested were significantly defective in nitrate-dependent Fe(II) oxidation. The non-defective mutants included the c1-cytochrome subunit of the cytochrome bc1 complex (complex III), which has relevance to a previously proposed role for this complex in nitrate-dependent Fe(II) oxidation and to current concepts of reverse electron transfer. Of the transposon mutants defective in Fe(II) oxidation, one mutant with a disrupted gene associated with NADH:ubiquinone oxidoreductase (complex I) was ~35% defective relative to the wild-type strain; this strain was similarly defective in nitrate reduction with thiosulfate as the electron donor. Overall, our results indicate that nitrate-dependent Fe(II) oxidation in T. denitrificans is not catalyzed by the same c-type cytochromes involved in U(IV) oxidation, nor have other c-type cytochromes yet been implicated in the process.

  17. Sr flux stability against oxidation in oxide-molecular-beam-epitaxy environment: Flux, geometry, and pressure dependence

    International Nuclear Information System (INIS)

    Maintaining stable fluxes for multiple source elements is a challenging task when the source materials have significantly different oxygen affinities in a complex-oxide molecular-beam-epitaxy (MBE) environment. Considering that Sr is one of the most easily oxidized and widely used elements in various complex oxides, we took Sr as a probe to investigate the flux-stability problem in a number of different conditions. Source oxidation was less for higher flux, extended port geometry, and unmelted source shape. The extended port geometry also eliminated the flux transient after opening a source shutter as observed in the standard port. We also found that the source oxidation occurred more easily on the crucible wall than on the surface of the source material. Atomic oxygen, in spite of its stronger oxidation effectiveness, did not make any difference in source oxidation as compared to molecular oxygen in this geometry. Our results may provide a guide for solutions to the source oxidation problem in oxide-MBE system.

  18. Thickness dependence of mechanical properties of free-standing graphene oxide papers

    Science.gov (United States)

    Gong, Tao; Lam, Do Van; Won, Sejeong; Liu, Renlong; Yun, Hwangbo; Kwon, Sanghyuk; Kim, Jinseon; Sun, Ke; Lee, Seungmo; Lee, Changgu; Graphene engineering lab Team; Nanomechanics Lab Collaboration

    2015-03-01

    We have characterized thickness dependence of mechanical properties, such as Young's modulus, fracture strength, fracture strain and toughness, of graphene oxide papers using tensile and bulge test methods. The GO papers were made from Hummer's method and the fabricated GO paper's thickness varied from 0.1 ~ 100 μm. The measured Young's modulus and fracture strength decreased with increasing thickness ranging from 44.6 ~ 8.5GPa and 170.2 ~ 40MPa respectively. Through TEM, SEM and AFM characterization, the inner structure and surface morphology such as crack formation and roughness change are the keys to the variation of mechanical properties in the GO papers by the thickness. The thicker GO papers are weaker because it has more manufacturing voids in it that cause it to fail easily and less stiff. Surface wrinkle and residual stress are the mechanism of terraced fracture strain.

  19. Electrode dependent interfacial layer variation in metal-oxide-semiconductor capacitor

    International Nuclear Information System (INIS)

    The interfacial layer between oxide and semiconductor in metal-oxide-semiconductor (MOS) capacitors depends on the metal electrode material. The metal/HfO2/Si and metal/HfO2/Ge capacitor were made using an atomic layer deposited HfO2 dielectric films and Mo, Ru, and Pt electrodes above Si substrate and Ti, Ru, and Pt electrodes above Ge substrate. The measured saturation capacitance was varied with electrode and evaluated to capacitance equivalent thickness (CET). In Si-based MOS capacitor, the CET value of the capacitor with Pt electrode is larger than those with Mo and Ru electrode. In addition, the CET is 27.4 A, 38.2 A, and 30.8 A for Ti, Ru, and Pt electrode, respectively, for Ge-based MOS capacitors. The CET variation with electrode is attributed the variation of dielectric constant of HfO2 dielectric and the difference of interfacial layer. The CET variation is well in agreement with the interfacial layer thickness taken by a transmission electron microscopy. The thickness variation of interfacial layer results from the oxygen gettering ability of the electrode even though they are apart

  20. Hydroxylamine-dependent Anaerobic Ammonium Oxidation (Anammox) by “ Candidatus Brocadia sinica”

    KAUST Repository

    Oshiki, Mamoru

    2016-04-26

    Although metabolic pathways and associated enzymes of anaerobic ammonium oxidation (anammox) of “Ca. Kuenenia stuttgartiensis” have been studied, those of other anammox bacteria are still poorly understood. NO2- reduction to NO is considered to be the first step in the anammox metabolism of “Ca. K. stuttgartiensis”, however, “Ca. Brocadia” lacks the genes that encode canonical NO-forming nitrite reductases (NirS or NirK) in its genome, which is different from “Ca. K. stuttgartiensis”. Here, we studied the anammox metabolism of “Ca. Brocadia sinica”. 15N-tracer experiments demonstrated that “Ca. B. sinica” cells could reduce NO2- to NH2OH, instead of NO, with as yet unidentified nitrite reductase(s). Furthermore, N2H4 synthesis, downstream reaction of NO2- reduction, was investigated using a purified “Ca. B. sinica” hydrazine synthase (Hzs) and intact cells. Both the “Ca. B. sinica” Hzs and cells utilized NH2OH and NH4+, but not NO and NH4+, for N2H4 synthesis and further oxidized N2H4 to N2 gas. Taken together, the metabolic pathway of “Ca. B. sinica” is NH2OH-dependent and different from the one of “Ca. K. stuttgartiensis”, indicating metabolic diversity of anammox bacteria. This article is protected by copyright. All rights reserved.

  1. Effect of simvastatin on endothelium-dependent vasorelaxation and endogenous nitric oxide synthase inhibitor

    Institute of Scientific and Technical Information of China (English)

    Jun-lin JIANG; De-jian JIANG; Yu-hai TANG; Nian-sheng LI; Han-wu DENG; Yuan-jian LI

    2004-01-01

    AIM: To investigate the effect of simvastatin on endothelium-dependent vasorelaxation and endogenous nitric oxide synthesis inhibitor asymmetric dimethylarginine (ADMA) in rats and cultured ECV304 cells. METHODS: Endothelial injury was induced by a single injection of low density lipoprotein (LDL) (4 mg/kg, 48 h) in rats or incubation with LDL (300 mg/L) or oxidative-modified LDL (100 mg/L) in cultured ECV304 cells, and vasodilator responses to acetylcholine (ACh) in the aortic rings and the level of ADMA, nitrite/nitrate (NO) and tumor necrosis factoralpha (TNF-α) in the serum or cultured medium were determined. And the adhesion of the monocytes to endothelial cells and the activity of dimethylarginine dimethylaminohydrolase (DDAH) in the cultured ECV304 cells were measured. RESULTS: A single injection of LDL decreased endothelium-dependent relaxation to ACh, markedly increased the serum level of endogenous ADMA and TNF-α, and reduced serum level of NO. Pretreatment with simvastatin (30 or 60 mg/kg) markedly attenuated inhibition of vasodilator responses to ACh, the increased level of TNF-α and the decreased level of NO by LDL, but no effect on serum concentration of endogenous ADMA. In cultured ECV304 cells, LDL or ox-LDL markedly increased the level of ADMA and TNF-α and potentiated the adhesion of monocytes to endothelial cells, concomitantly with a significantly decrease in the activity of DDAH and serum level of NO. Pretreatment with simvastatin (0.1, 0.5, or 2.5 μmol/L) markedly decreased the level of TNFo and the adhesion of monocytes to endothelial cells, but did not affect the concentration of endogenous ADMA and the activity of DDAH. CONCLUSION: Simvastatin protect the vascular endothelium against the damages induced by LDL or ox-LDL in rats or cultured ECV304 cells, and the beneficial effects of simvastatin may be related to the reduction of inflammatory cytokine TNF-o level.

  2. Cellular Metabolism and Dose Reveal Carnitine-Dependent and -Independent Mechanisms of Butyrate Oxidation in Colorectal Cancer Cells.

    Science.gov (United States)

    Han, Anna; Bennett, Natalie; MacDonald, Amber; Johnstone, Megan; Whelan, Jay; Donohoe, Dallas R

    2016-08-01

    Dietary fiber has been suggested to suppress colorectal cancer development, although the mechanisms contributing to this beneficial effect remain elusive. Butyrate, a fermentation product of fiber, has been shown to have anti-proliferative and pro-apoptotic effects on colorectal cancer cells. The metabolic fate of butyrate in the cell is important in determining whether, it acts as an HDAC inhibitor or is consumed as a short-chain fatty acid. Non-cancerous colonocytes utilize butyrate as the primary energy source whereas cancerous colonocytes increase glucose utilization through the Warburg effect. In this study, we show that butyrate oxidation is decreased in cancerous colonocytes compared to non-cancerous colonocytes. We demonstrate that colorectal cancer cells utilize both a carnitine-dependent and carnitine-independent mechanism that contributes to butyrate oxidation. The carnitine-dependent mechanism is contingent on butyrate concentration. Knockdown of CPT1A in colorectal cancer cells abolishes butyrate oxidation. In terms of selectivity, the carnitine-dependent mechanism only regulated butyrate oxidation, as acetate and propionate oxidation were carnitine-independent. Carnitine decreased the action of butyrate as an HDAC inhibitor and suppressed induction of H3 acetylation by butyrate in colorectal cancer cells. Thus, diminished oxidation of butyrate is associated with decreased HDAC inhibition and histone acetylation. In relation to the mechanism, we find that dichloroacetate, which decreases phosphorylation of pyruvate dehydrogenase, increased butyrate oxidation and that this effect was carnitine-dependent. In conclusion, these data suggest that colorectal cancer cells decrease butyrate oxidation through inhibition of pyruvate dehydrogenase, which is carnitine-dependent, and provide insight into why butyrate shows selective effects toward colorectal cancer cells. J. Cell. Physiol. 231: 1804-1813, 2016. © 2015 Wiley Periodicals, Inc. PMID:26661480

  3. Hyperglycaemia-induced impairment of endothelium-dependent vasorelaxation in rat mesenteric arteries is mediated by intracellular methylglyoxal levels in a pathway dependent on oxidative stress

    DEFF Research Database (Denmark)

    Brouwers, O; Niessen, P M; Haenen, G;

    2010-01-01

    of high glucose and methylglyoxal on NO-dependent vasorelaxation in isolated rat mesenteric arteries from wild-type and transgenic glyoxalase (GLO)-I (also known as GLO1) rats, i.e. the enzyme detoxifying methylglyoxal, were recorded in a wire myograph. AGE formation of the major methylglyoxal-adduct 5...... for AGE ligand S100b did (p stress marker nitrotyrosine. Antioxidant pre-incubation prevented methylglyoxal......-induced impairment of vasoreactivity. CONCLUSIONS/INTERPRETATION: These data show that hyperglycaemia-induced impairment of endothelium-dependent vasorelaxation is mediated by increased intracellular methylglyoxal levels in a pathway dependent on oxidative stress....

  4. Acute dairy milk ingestion does not improve nitric oxide-dependent vasodilation in the cutaneous microcirculation.

    Science.gov (United States)

    Alba, Billie K; Stanhewicz, Anna E; Kenney, W Larry; Alexander, Lacy M

    2016-07-01

    In epidemiological studies, chronic dairy milk consumption is associated with improved vascular health and reduced age-related increases in blood pressure. Although milk protein supplementation augments conduit artery flow-mediated dilation, whether or not acute dairy milk intake may improve microvascular function remains unclear. We hypothesised that dairy milk would increase direct measurement of endothelial nitric oxide (NO)-dependent cutaneous vasodilation in response to local skin heating. Eleven men and women (61 (sem 2) years) ingested two or four servings (473 and 946 ml) of 1 % dairy milk or a rice beverage on each of 4 separate study days. In a subset of five subjects, an additional protocol was completed after 473 ml of water ingestion. Once a stable blood flow occurred, 15 mm-N G -nitro-l-arginine methyl ester was perfused (intradermal microdialysis) to quantify NO-dependent vasodilation. Red-blood-cell flux (RBF) was measured by laser-Doppler flowmetry, and cutaneous vascular conductance (CVC=RBF/mean arterial pressure) was calculated and normalised to maximum (%CVCmax; 28 mm-sodium nitroprusside). Full expression of cutaneous vasodilation was not different among dairy milk, rice beverage and water, and there was no effect of serving size on the total vasodilatory response. Contrary to our hypothesis, NO-dependent vasodilation was lower for dairy milk than rice beverage (D: 49 (sem 5), R: 55 (sem 5) %CVCmax; P<0·01). Acute dairy milk ingestion does not augment NO-dependent vasodilation in the cutaneous microcirculation compared with a rice beverage control. PMID:27180680

  5. Time dependent thermal treatment of oxidized MWCNTs studied by the electron and mass spectroscopy methods

    International Nuclear Information System (INIS)

    Purified and functionalized in boiling concentrated (68%) HNO3 acid the oxidized multiwall carbon nanotubes (ox-MWCNTs) under thermal treatment from RT to 630 °C and at 350 °C time dependent (1-4 h) were investigated using the surface sensitive electron and mass spectroscopy methods. Mass spectroscopy indicates significant desorption of H2 and H2O to about 300 °C. Higher H2 desorption rate from RT up to about 100 °C is most likely caused by decomposition of organic acid impurities included within a bundle and in channels of the ox-MWCNTs after their functionalization by HNO3. In the range of 100-300 °C part of the detected H2, accompanied by desorption of CO2, may origin from desorbed water. Above 300 °C, the small amount of desorbing H2O may result from transformation of carboxylic groups into carboxylic acid anhydride. Significant desorption of CO2 starting from 150 °C may result from decomposition of carboxylic groups, whereas desorption of CO starting at about 300 °C from decomposition of acid anhydride groups created from carboxylic groups during thermal dehydration. Desorption of CO and CO2 at about 470 °C may be due to decomposition of hydroxyl O-H and carbonyl C=O groups. Above 600 °C mainly decomposition of C=O groups takes place and results in small desorption of CO. Time dependent (1-4 h) thermal treatment of ox-MWCNTs at 350 °C shows in XPS spectra decreasing amount of C-O in carboxyl groups and increasing amount of C=O in carbonyl and acid anhydride groups arising from carboxyl groups decomposition. Between 350 °C and 470 °C the higher desorption rate of CO2 than CO indicates significant decomposition of carboxyl and carboxyl anhydride groups. At 350 °C the dynamic changes are indicated by the energy, intensity and full width at half maximum (FWHM) of the π → π* interband transition and π loss peak, and quasi-elastic peak FWHM. During 4 h at 350 °C no C sp2 reconstruction is observed. For the applied procedure of MWCNTs oxidation

  6. Oxygen as Intermediate in Anoxic Environments: Nitrite-Dependent Methane Oxidation and Beyond

    Science.gov (United States)

    Ettwig, K. F.

    2014-12-01

    In recent years the known diversity of hydrocarbon activation mechanisms under anaerobic conditions has been extended by intra-aerobic denitrification, a process in which oxygen is derived from NO and used for substrate activation. For two phylogenetically unrelated bacterial species, the freshwater NC10 phylum bacterium Methylomirabilis oxyfera [1] and the marine γ-proteobacterial strain HdN1 [2] it has been shown that, under anoxic conditions with nitrate and/or nitrite, mono-oxygenases are used for methane and hexadecane oxidation, respectively. No degradation was observed with nitrous oxide (N2O) only. In the anaerobic methanotroph M. oxyfera, which lacks apparent nitrous oxide reductase in its genome, substrate activation in the presence of nitrite was directly associated with both O2 and N2 formation. These findings strongly argue for the role of nitric oxide (NO), or an oxygen species derived from it, in the activation reaction of methane. Although intracellular oxygen generation has been experimentally documented and elegantly explains the utilization of 'aerobic' pathways under anoxic conditions, research about the underlying molecular mechanism has just started. The proposed candidate enzymes for oxygen (or possibly another another reactive intermediate) production from NO, an NO dismutase (NOD) [3], related to quinol-dependent NO reductases (qNORs), is present and highly expressed in both M. oxyfera and strain HdN1. Besides that, several recently sequenced species from the Cytophaga-Flavobacterium-Bacteroides group harbor Nod/Nor genes, but experimential evidence is needed to show if these have NOD activity, are unusual but functional qNORs, or represent transition states between the two. Additionally, for several anaerobic hydrocarbon-degrading organisms the biochemical mechanism of substrate activation has not been elucidated yet: whereas signature genes of anaerobic degradation are missing, monooxygenase genes are present. Also these microorganisms

  7. Applicability of anaerobic nitrate-dependent Fe(II) oxidation to microbial enhanced oil recovery (MEOR).

    Science.gov (United States)

    Zhu, Hongbo; Carlson, Han K; Coates, John D

    2013-08-01

    Microbial processes that produce solid-phase minerals could be judiciously applied to modify rock porosity with subsequent alteration and improvement of floodwater sweep in petroleum reservoirs. However, there has been little investigation of the application of this to enhanced oil recovery (EOR). Here, we investigate a unique approach of altering reservoir petrology through the biogenesis of authigenic rock minerals. This process is mediated by anaerobic chemolithotrophic nitrate-dependent Fe(II)-oxidizing microorganisms that precipitate iron minerals from the metabolism of soluble ferrous iron (Fe(2+)) coupled to the reduction of nitrate. This mineral biogenesis can result in pore restriction and reduced pore throat diameter. Advantageously and unlike biomass plugs, these biominerals are not susceptible to pressure or thermal degradation. Furthermore, they do not require continual substrate addition for maintenance. Our studies demonstrate that the biogenesis of insoluble iron minerals in packed-bed columns results in effective hydrology alteration and homogenization of heterogeneous flowpaths upon stimulated microbial Fe(2+) biooxidation. We also demonstrate almost 100% improvement in oil recovery from hydrocarbon-saturated packed-bed columns as a result of this metabolism. These studies represent a novel departure from traditional microbial EOR approaches and indicate the potential for nitrate-dependent Fe(2+) biooxidation to improve volumetric sweep efficiency and enhance both the quality and quantity of oil recovered. PMID:23799785

  8. Size dependence of the magnetic relaxation and specific power absorption in iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lima, E. [CONICET and Instituto de Nanociencia y Nanotecnologia and Centro Atomico Bariloche (Argentina); Torres, T. E. [University of Zaragoza, Instituto de Nanociencia de Aragon (INA) and Departamento de Fisica de la Materia Condensada and Laboratorio de Microscopias Avanzadas (LMA) (Spain); Rossi, L. M. [Instituto de Quimica, Universidade de Sao Paulo (Brazil); Rechenberg, H. R. [Instituto de Fisica, Universidade de Sao Paulo (Brazil); Berquo, T. S. [Institute of Rock Magnetism, University of Minnesota (United States); Ibarra, A. [University of Zaragoza, INA and LMA (Spain); Marquina, C. [CSIC, Universidad de Zaragoza, Departamento de Fisica de la Materia Condensada and Instituto de Ciencia de Materiales de Aragon (ICMA) (Spain); Ibarra, M. R. [University of Zaragoza, INA and Departamento de Fisica de la Materia Condensada and LMA (Spain); Goya, G. F., E-mail: goya@unizar.es [University of Zaragoza, INA and Departamento de Fisica de la Materia Condensada (Spain)

    2013-05-15

    In this study, magnetic and power absorption properties of a series of iron oxide nanoparticles with average sizes Left-Pointing-Angle-Bracket d Right-Pointing-Angle-Bracket ranging from 3 to 23 nm were reported. The nanoparticles were prepared by thermal decomposition of Iron(III) acetylacetonate in organic media. From the careful characterization of the magnetic and physicochemical properties of these samples, the specific power absorption (SPA) values experimentally found were numerically reproduced, as well as their dependence with particle size, using a simple model of Brownian and Neel relaxation at room temperature. SPA experiments in ac magnetic fields (H{sub 0} = 13 kA/m and f = 250 kHz) indicated that the magnetic and rheological properties played a crucial role determining the heating efficiency at different conditions. A maximum SPA value of 344 W/g was obtained for a sample containing nanoparticles with Left-Pointing-Angle-Bracket d Right-Pointing-Angle-Bracket = 12 nm and dispersion {sigma} = 0.25. The observed SPA dependence with particle diameter and their magnetic parameters indicated that, for the size range and experimental conditions of f and H studied in this study, both Neel and Brown relaxation mechanisms are important to the heat generation observed.

  9. Functional interaction of endothelial nitric oxide synthase with a voltage-dependent anion channel

    Science.gov (United States)

    Sun, Jianxin; Liao, James K.

    2002-01-01

    Endothelium-derived nitric oxide (NO) is an important regulator of vascular function. NO is produced by endothelial NO synthase (eNOS) whose function is modulated, in part, by specific protein interactions. By coimmunoprecipitation experiments followed by MS analyses, we identified a human voltage-dependent anion/cation channel or porin as a binding partner of eNOS. The interaction between porin and eNOS was demonstrated by coimmunoprecipitation studies in nontransfected human endothelial cells and Cos-7 cells transiently transfected with eNOS and porin cDNAs. In vitro binding studies with glutathione S-transferase–porin indicated that porin binds directly to eNOS and that this interaction augmented eNOS activity. The calcium ionophore, A23187, and bradykinin, which are known to activate eNOS, markedly increased porin–eNOS interaction, suggesting a potential role of intracellular Ca2+ in mediating this interaction. Theses results indicate that the interaction between a voltage-dependent membrane channel and eNOS may be important for regulating eNOS activity. PMID:12228731

  10. Self-Adaptive Spike-Time-Dependent Plasticity of Metal-Oxide Memristors

    Science.gov (United States)

    Prezioso, M.; Merrikh Bayat, F.; Hoskins, B.; Likharev, K.; Strukov, D.

    2016-02-01

    Metal-oxide memristors have emerged as promising candidates for hardware implementation of artificial synapses - the key components of high-performance, analog neuromorphic networks - due to their excellent scaling prospects. Since some advanced cognitive tasks require spiking neuromorphic networks, which explicitly model individual neural pulses (“spikes”) in biological neural systems, it is crucial for memristive synapses to support the spike-time-dependent plasticity (STDP). A major challenge for the STDP implementation is that, in contrast to some simplistic models of the plasticity, the elementary change of a synaptic weight in an artificial hardware synapse depends not only on the pre-synaptic and post-synaptic signals, but also on the initial weight (memristor’s conductance) value. Here we experimentally demonstrate, for the first time, an STDP behavior that ensures self-adaptation of the average memristor conductance, making the plasticity stable, i.e. insensitive to the initial state of the devices. The experiments have been carried out with 200-nm Al2O3/TiO2-x memristors integrated into 12 × 12 crossbars. The experimentally observed self-adaptive STDP behavior has been complemented with numerical modeling of weight dynamics in a simple system with a leaky-integrate-and-fire neuron with a random spike-train input, using a compact model of memristor plasticity, fitted for quantitatively correct description of our memristors.

  11. Graphene oxide-dependent growth and self-aggregation into a hydrogel complex of exoelectrogenic bacteria.

    Science.gov (United States)

    Yoshida, Naoko; Miyata, Yasushi; Doi, Kasumi; Goto, Yuko; Nagao, Yuji; Tero, Ryugo; Hiraishi, Akira

    2016-01-01

    Graphene oxide (GO) is reduced by certain exoelectrogenic bacteria, but its effects on bacterial growth and metabolism are a controversial issue. This study aimed to determine whether GO functions as the terminal electron acceptor to allow specific growth of and electricity production by exoelectrogenic bacteria. Cultivation of environmental samples with GO and acetate as the sole substrate could specifically enrich exoelectrogenic bacteria with Geobacter species predominating (51-68% of the total populations). Interestingly, bacteria in these cultures self-aggregated into a conductive hydrogel complex together with biologically reduced GO (rGO). A novel GO-respiring bacterium designated Geobacter sp. strain R4 was isolated from this hydrogel complex. This organism exhibited stable electricity production at >1000 μA/cm(3) (at 200 mV vs Ag/AgCl) for more than 60 d via rGO while temporary electricity production using graphite felt. The better electricity production depends upon the characteristics of rGO such as a large surface area for biofilm growth, greater capacitance, and smaller internal resistance. This is the first report to demonstrate GO-dependent growth of exoelectrogenic bacteria while forming a conductive hydrogel complex with rGO. The simple put-and-wait process leading to the formation of hydrogel complexes of rGO and exoelectrogens will enable wider applications of GO to bioelectrochemical systems. PMID:26899353

  12. Nitric Oxide-associated Protein 1 (NOA1) Is Necessary for Oxygen-dependent Regulation of Mitochondrial Respiratory Complexes*

    OpenAIRE

    Heidler, Juliana; Al-Furoukh, Natalie; Kukat, Christian; Salwig, Isabelle; Ingelmann, Marie-Elisabeth; Seibel, Peter; Krüger, Marcus; Holtz, Jürgen; Wittig, Ilka; Braun, Thomas; Szibor, Marten

    2011-01-01

    In eukaryotic cells, maintenance of cellular ATP stores depends mainly on mitochondrial oxidative phosphorylation (OXPHOS), which in turn requires sufficient cellular oxygenation. The crucial role of proper oxygenation for cellular viability is reflected by involvement of several mechanisms, which sense hypoxia and regulate activities of respiratory complexes according to available oxygen concentrations. Here, we focus on mouse nitric oxide-associated protein 1 (mNOA1), which has been identif...

  13. Final Report: Molecular mechanisms and kinetics of microbial anaerobic nitrate-dependent U(IV) and Fe(II) oxidation

    Energy Technology Data Exchange (ETDEWEB)

    O' Day, Peggy A. [Univ. of California, Merced, CA (United States); Asta, Maria P. [Univ. of California, Merced, CA (United States); Kanematsu, Masakazu [Univ. of California, Merced, CA (United States); Beller, Harry [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zhou, Peng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Steefel, Carl [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-02-27

    In this project, we combined molecular genetic, spectroscopic, and microscopic techniques with kinetic and reactive transport studies to describe and quantify biotic and abiotic mechanisms underlying anaerobic, nitrate-dependent U(IV) and Fe(II) oxidation, which influences the long-term efficacy of in situ reductive immobilization of uranium at DOE sites. In these studies, Thiobacillus denitrificans, an autotrophic bacterium that catalyzes anaerobic U(IV) and Fe(II) oxidation, was used to examine coupled oxidation-reduction processes under either biotic (enzymatic) or abiotic conditions in batch and column experiments with biogenically produced UIVO2(s). Synthesis and quantitative analysis of coupled chemical and transport processes were done with the reactive transport modeling code Crunchflow. Research focused on identifying the primary redox proteins that catalyze metal oxidation, environmental factors that influence protein expression, and molecular-scale geochemical factors that control the rates of biotic and abiotic oxidation.

  14. The Apparent Involvement of ANMEs in Mineral Dependent Methane Oxidation, as an Analog for Possible Martian Methanotrophy.

    Science.gov (United States)

    House, Christopher H; Beal, Emily J; Orphan, Victoria J

    2011-01-01

    On Earth, marine anaerobic methane oxidation (AOM) can be driven by the microbial reduction of sulfate, iron, and manganese. Here, we have further characterized marine sediment incubations to determine if the mineral dependent methane oxidation involves similar microorganisms to those found for sulfate-dependent methane oxidation. Through FISH and FISH-SIMS analyses using 13C and 15N labeled substrates, we find that the most active cells during manganese dependent AOM are primarily mixed and mixed-cluster aggregates of archaea and bacteria. Overall, our control experiment using sulfate showed two active bacterial clusters, two active shell aggregates, one active mixed aggregate, and an active archaeal sarcina, the last of which appeared to take up methane in the absence of a closely-associated bacterial partner. A single example of a shell aggregate appeared to be active in the manganese incubation, along with three mixed aggregates and an archaeal sarcina. These results suggest that the microorganisms (e.g., ANME-2) found active in the manganese-dependent incubations are likely capable of sulfate-dependent AOM. Similar metabolic flexibility for Martian methanotrophs would mean that the same microbial groups could inhabit a diverse set of Martian mineralogical crustal environments. The recently discovered seasonal Martian plumes of methane outgassing could be coupled to the reduction of abundant surface sulfates and extensive metal oxides, providing a feasible metabolism for present and past Mars. In an optimistic scenario Martian methanotrophy consumes much of the periodic methane released supporting on the order of 10,000 microbial cells per cm2 of Martian surface. Alternatively, most of the methane released each year could be oxidized through an abiotic process requiring biological methane oxidation to be more limited. If under this scenario, 1% of this methane flux were oxidized by biology in surface soils or in subsurface aquifers (prior to release), a total

  15. The Apparent Involvement of ANMEs in Mineral Dependent Methane Oxidation, as an Analog for Possible Martian Methanotrophy

    Directory of Open Access Journals (Sweden)

    Victoria J. Orphan

    2011-11-01

    Full Text Available On Earth, marine anaerobic methane oxidation (AOM can be driven by the microbial reduction of sulfate, iron, and manganese. Here, we have further characterized marine sediment incubations to determine if the mineral dependent methane oxidation involves similar microorganisms to those found for sulfate-dependent methane oxidation. Through FISH and FISH-SIMS analyses using 13C and 15N labeled substrates, we find that the most active cells during manganese dependent AOM are primarily mixed and mixed-cluster aggregates of archaea and bacteria. Overall, our control experiment using sulfate showed two active bacterial clusters, two active shell aggregates, one active mixed aggregate, and an active archaeal sarcina, the last of which appeared to take up methane in the absence of a closely-associated bacterial partner. A single example of a shell aggregate appeared to be active in the manganese incubation, along with three mixed aggregates and an archaeal sarcina. These results suggest that the microorganisms (e.g., ANME-2 found active in the manganese-dependent incubations are likely capable of sulfate-dependent AOM. Similar metabolic flexibility for Martian methanotrophs would mean that the same microbial groups could inhabit a diverse set of Martian mineralogical crustal environments. The recently discovered seasonal Martian plumes of methane outgassing could be coupled to the reduction of abundant surface sulfates and extensive metal oxides, providing a feasible metabolism for present and past Mars. In an optimistic scenario Martian methanotrophy consumes much of the periodic methane released supporting on the order of 10,000 microbial cells per cm2 of Martian surface. Alternatively, most of the methane released each year could be oxidized through an abiotic process requiring biological methane oxidation to be more limited. If under this scenario, 1% of this methane flux were oxidized by biology in surface soils or in subsurface aquifers (prior to

  16. Deltamethrin-induced oxidative stress and mitochondrial caspase-dependent signaling pathways in murine splenocytes.

    Science.gov (United States)

    Kumar, Anoop; Sasmal, D; Bhaskar, Amand; Mukhopadhyay, Kunal; Thakur, Aman; Sharma, Neelima

    2016-07-01

    Deltamethrin (DLM) is a well-known pyrethroid insecticide used extensively in pest control. Exposure to DLM has been demonstrated to cause apoptosis in various cells. However, the immunotoxic effects of DLM on mammalian system and its mechanism is still an open question to be explored. To explore these effects, this study has been designed to first observe the interactions of DLM to immune cell receptors and its effects on the immune system. The docking score revealed that DLM has strong binding affinity toward the CD45 and CD28 receptors. In vitro study revealed that DLM induces apoptosis in murine splenocytes in a concentration-dependent manner. The earliest markers of apoptosis such as enhanced reactive oxygen species and caspase 3 activation are evident as early as 1 h by 25 and 50 µM DLM. Western blot analysis demonstrated that p38 MAP kinase and Bax expression is increased in a concentration-dependent manner, whereas Bcl 2 expression is significantly reduced after 3 h of DLM treatment. Glutathione depletion has been also observed at 3 and 6 h by 25 and 50 µM concentration of DLM. Flow cytometry results imply that the fraction of hypodiploid cells has gradually increased with all the concentrations of DLM at 18 h. N-acetyl cysteine effectively reduces the percentage of apoptotic cells, which is increased by DLM. In contrast, buthionine sulfoxamine causes an elevation in the percentage of apoptotic cells. Phenotyping data imply the effect of DLM toxicity in murine splenocytes. In brief, the study demonstrates that DLM causes apoptosis through its interaction with CD45 and CD28 receptors, leading to oxidative stress and activation of the mitochondrial caspase-dependent pathways which ultimately affects the immune functions. This study provides mechanistic information by which DLM causes toxicity in murine splenocytes. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 808-819, 2016. PMID:25534813

  17. MOLECULAR WEIGHT DEPENDENCE OF CRYSTAL PATTERN TRANSITIONS OF POLY(ETHYLENE OXIDE)

    Institute of Scientific and Technical Information of China (English)

    Guo-liang Zhang; Liu-xin Jin; Ping Zheng; Wei Wang; Xiao-jing Wen

    2013-01-01

    Crystal patterns in ultrathin films of six poly(ethylene oxide) fractions with molecular weights from 25000 to 932000 g/mol were characterized within crystallization temperature range from 20 ℃ to 60 ℃.Labyrinthine,dendritic and faceted crystal patterns were observed in different temperature ranges,and then labyrinthine-to-dendritic and dendritic-tofaceted transition temperatures TL-D and TD-F were quantitatively identified.Their molecular weight dependences are TL-D(Mw) =TL-D(∞)-KL-D/Mw,where TL-D(∞) =38.2 ℃ and KL-D =253000 ℃·g/mol and TD-F(Mw) =TD-F(∞)-KD-F/Mw,where TD-F(∞) =54.7 ℃ and KD-F =27000 ℃·g/mol.Quasi two-dimensional blob models were proposed to provide empirical explanations of the molecular weight dependences.The labyrinthine-to-dendritic transition is attributed to a molecular diffusion process change from a local-diffusion to diffusion-limited-aggregation (DLA) and a polymer chain with Mw ≈ 253000 g/mol within a blob can join crystals independently.The dendritic-to-faceted transition is attributed to a turnover of the pattern formation mechanism from DLA to crystallization control,and a polymer chain with a Mw ≈ 27000g/mol as an independent blob crosses to a depletion zone to join crystals.These molecular weight dependences reveal a macromolecular effect on the crystal pattern formation and selection of crystalline polymers.

  18. Marker behaviour of implanted xenon during the anodic oxidation of aluminium: evidence and interpretation of dose dependant splitting effect

    International Nuclear Information System (INIS)

    Using 2 MeV lithium ions backscattering and transmission electron microscopy techniques, a part of xenon atoms introduced by implantation in aluminium metal under the initial oxide layer is shown to be tranported by the moving metal-oxide interface during anodic oxidation. From specific anodization conditions (V sup(ct), T = 900C) this splitting of the initial xenon distribution is interpreted in terms of bubble formation and growth above a given local concentration threshold. A schematic model for this behaviour evolution is proposed. This dose dependance is of practical interest in the determination of transport numbers. Although unambiguously measured they may be subject to significant systematic uncertainties which are discussed

  19. Frequency and temperature dependent transport properties of NiCuZn ceramic oxide

    Directory of Open Access Journals (Sweden)

    Hossen M. Belal

    2015-06-01

    Full Text Available A polycrystalline sample of ceramic oxide Ni0.27Cu0.10Zn0.63Fe2O4 was prepared by the solid state reaction method. The sintered sample was well polished to remove any oxide layer formed during sintering and the two surfaces of the pellet were coated with a silver paste as a contact material. Among dielectric properties, complex dielectric constant (ε* = εʹ - jεʺ, loss tangent (tanδ and ac conductivity (σac in the frequency range of 20 Hz to 2 MHz were analyzed in the temperature range of 303 to 498 K using a Wayne Kerr impedance analyzer (model No. 6500B. The experimental results indicate that ε, εʺ, tanδ and σac decrease with an increase in frequency and increase with increasing temperature. The transition temperature, as obtained from dispersion curve of εʹ, shifts towards higher temperature with an increase in frequency. The variation of dielectric properties with frequency and temperature shows the dispersion behavior which is explained in the light of Maxwell-Wagner type of interfacial polarization in accordance with the Koop’s phenomenological theory. The frequency dependent conductivity results satisfy the Jonscher’s power law, σT(ω = σ(o+Aωn, and the results show the occurrence of two types of conduction process at elevated temperature: (i low frequency conductivity, due to long-range ordering (frequency independent, region I, (ii mid frequency conductivity at the grain boundaries (region II, dispersion and (iii high frequency conductivity at the grain interior due to the short-range hopping mechanism (frequency independent plateau, region III.

  20. Dependence of Heterogeneous OH Kinetics with Biomass Burning Aerosol Proxies on Oxidant Concentration and Relative Humidity

    Science.gov (United States)

    Slade, J. H.; Knopf, D. A.

    2013-12-01

    Chemical transformations of aerosol particles by heterogeneous reactions with trace gases such as OH radicals can influence particle physicochemical properties and lifetime, affect cloud formation, light scattering, and human health. Furthermore, OH oxidation can result in degradation of particle mass by volatilization reactions, altering the budget of volatile organic compounds (VOCs). However, the reactive uptake coefficient (γ) and particle oxidation degree can vary depending on several factors including oxidant concentration and relative humidity (RH). While RH can influence the extent of dissociation/ionization, it can also affect particle phase and thus oxidant diffusivity. Only one study so far has investigated the effect of RH on the rate of OH uptake to organic surfaces; however, the underlying processes affecting OH reactivity with organic aerosol under humidified conditions still remains elusive. Here, we determine the effect of RH on OH reactivity with laboratory-generated biomass burning aerosol (BBA) surrogate particles: levoglucosan and 4-methyl-5-nitrocatechol. The effect of OH concentration on γ for three common BBA molecular markers (levoglucosan, abietic acid, and nitroguaiacol) under dry conditions was investigated from [OH]≈107-1011 molecule cm-3, covering both [OH] in biomass burning plumes and [OH] commonly used in particle aging studies. Furthermore, key VOC reaction products and their production pathways resulting from BBA volatilization by OH were identified. OH radicals are produced using a microwave induced plasma (MIP) of H2 in He or Ar followed by reaction with O2, or by photolysis of O3 in the presence of H2O. A cylindrical rotating wall flow-tube reactor and fast-flow aerosol flow reactor are used for conducting kinetic studies. OH is detected using a Chemical Ionization Mass Spectrometer (CIMS) and a Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS) is employed for VOC analysis. γ decreases from 0.2-0.5 at

  1. Fenofibrate suppressed proliferation and migration of human neuroblastoma cells via oxidative stress dependent of TXNIP upregulation

    Energy Technology Data Exchange (ETDEWEB)

    Su, Cunjin; Shi, Aiming; Cao, Guowen [Department of Pharmacy, The Second Affiliated Hospital of Soochow University, Suzhou, 215004 (China); Tao, Tao [Department of Urology, Zhongda Hospital, Medical School of Southeast University, Nanjing, 210009 (China); Chen, Ruidong [Department of Gastroenterology, The Second Affiliated Hospital of Soochow University, Suzhou, 215004 (China); Hu, Zhanhong; Shen, Zhu; Tao, Hong; Cao, Bin [Department of Pharmacy, The Second Affiliated Hospital of Soochow University, Suzhou, 215004 (China); Hu, Duanmin, E-mail: hudmsdfey@sina.com [Department of Gastroenterology, The Second Affiliated Hospital of Soochow University, Suzhou, 215004 (China); Bao, Junjie, E-mail: baojjsdfey@sina.com [Department of Pharmacy, The Second Affiliated Hospital of Soochow University, Suzhou, 215004 (China)

    2015-05-15

    There are no appropriate drugs for metastatic neuroblastoma (NB), which is the most common extra-cranial solid tumor for childhood. Thioredoxin binding protein (TXNIP), the endogenous inhibitor of ROS elimination, has been identified as a tumor suppressor in various solid tumors. It reported that fenofibrate exerts anti-tumor effects in several human cancer cell lines. However, its detail mechanisms remain unclear. The present study assessed the effects of fenofibrate on NB cells and investigated TXNIP role in its anti-tumor mechanisms. We used MTT assay to detect cells proliferation, starch wound test to investigate cells migration, H{sub 2}DCF-DA to detect intracellular ROS, siRNA to interfere TXNIP and peroxisome proliferator-androgen receptor-alpha (PPAR-α) expression, western blot to determine protein levels, flow cytometry to analyze apoptosis. Fenofibrate suppressed proliferation and migration of NB cells, remarkably increased intracellular ROS, upregulated TXNIP expression, promoted cell apoptosis. Furthermore, inhibition of TXNIP expression attenuated anti-tumor effects of fenofibrate, while inhibition of PPAR-α had no influences. Our results indicated the anti-tumor role of fenofibrate on NB cells by exacerbating oxidative stress and inducing apoptosis was dependent on the upregulation of TXNIP. - Highlights: • We found that fenofibrate suppressed proliferation and migration of NB cells. • We found that fenofibrate remarkably increased intracellular ROS, upregulated TXNIP expression, and promoted cell apoptosis. • Inhibition of TXNIP expression attenuated anti-tumor effects of fenofibrate, while inhibition of PPAR-α had no influences. • Our results indicated the anti-tumor role of fenofibrate on NB cells was dependent on the upregulation of TXNIP.

  2. Fenofibrate suppressed proliferation and migration of human neuroblastoma cells via oxidative stress dependent of TXNIP upregulation

    International Nuclear Information System (INIS)

    There are no appropriate drugs for metastatic neuroblastoma (NB), which is the most common extra-cranial solid tumor for childhood. Thioredoxin binding protein (TXNIP), the endogenous inhibitor of ROS elimination, has been identified as a tumor suppressor in various solid tumors. It reported that fenofibrate exerts anti-tumor effects in several human cancer cell lines. However, its detail mechanisms remain unclear. The present study assessed the effects of fenofibrate on NB cells and investigated TXNIP role in its anti-tumor mechanisms. We used MTT assay to detect cells proliferation, starch wound test to investigate cells migration, H2DCF-DA to detect intracellular ROS, siRNA to interfere TXNIP and peroxisome proliferator-androgen receptor-alpha (PPAR-α) expression, western blot to determine protein levels, flow cytometry to analyze apoptosis. Fenofibrate suppressed proliferation and migration of NB cells, remarkably increased intracellular ROS, upregulated TXNIP expression, promoted cell apoptosis. Furthermore, inhibition of TXNIP expression attenuated anti-tumor effects of fenofibrate, while inhibition of PPAR-α had no influences. Our results indicated the anti-tumor role of fenofibrate on NB cells by exacerbating oxidative stress and inducing apoptosis was dependent on the upregulation of TXNIP. - Highlights: • We found that fenofibrate suppressed proliferation and migration of NB cells. • We found that fenofibrate remarkably increased intracellular ROS, upregulated TXNIP expression, and promoted cell apoptosis. • Inhibition of TXNIP expression attenuated anti-tumor effects of fenofibrate, while inhibition of PPAR-α had no influences. • Our results indicated the anti-tumor role of fenofibrate on NB cells was dependent on the upregulation of TXNIP

  3. Nitric Oxide Exerts Basal and Insulin-Dependent Anorexigenic Actions in POMC Hypothalamic Neurons.

    Science.gov (United States)

    Wellhauser, Leigh; Chalmers, Jennifer A; Belsham, Denise D

    2016-04-01

    The arcuate nucleus of the hypothalamus represents a key center for the control of appetite and feeding through the regulation of 2 key neuronal populations, notably agouti-related peptide/neuropeptide Y and proopimelanocortin (POMC)/cocaine- and amphetamine-regulated transcript neurons. Altered regulation of these neuronal networks, in particular the dysfunction of POMC neurons upon high-fat consumption, is a major pathogenic mechanism involved in the development of obesity and type 2 diabetes mellitus. Efforts are underway to preserve the integrity or enhance the functionality of POMC neurons in order to prevent or treat these metabolic diseases. Here, we report for the first time that the nitric oxide (NO(-)) donor, sodium nitroprusside (SNP) mediates anorexigenic actions in both hypothalamic tissue and hypothalamic-derived cell models by mediating the up-regulation of POMC levels. SNP increased POMC mRNA in a dose-dependent manner and enhanced α-melanocortin-secreting hormone production and secretion in mHypoA-POMC/GFP-2 cells. SNP also enhanced insulin-driven POMC expression likely by inhibiting the deacetylase activity of sirtuin 1. Furthermore, SNP enhanced insulin-dependent POMC expression, likely by reducing the transcriptional repression of Foxo1 on the POMC gene. Prolonged SNP exposure prevented the development of insulin resistance. Taken together, the NO(-) donor SNP enhances the anorexigenic potential of POMC neurons by promoting its transcriptional expression independent and in cooperation with insulin. Thus, increasing cellular NO(-) levels represents a hormone-independent method of promoting anorexigenic output from the existing POMC neuronal populations and may be advantageous in the fight against these prevalent disorders. PMID:26930171

  4. Evaluation of the energy dependence of a zinc oxide nanofilm X-ray detector

    International Nuclear Information System (INIS)

    International organizations of human health and radiation protection have recommended certain care for using of the X-ray as a diagnosis tool to avoid any type of radiological accident or overdose to the patient. This can be done assessing the parameters of the X-ray equipment and there are various types of detectors available for that: ionizing chamber, electronic semiconductor devices, etc. These detectors must be calibrated so that they can be used for any energy range and such a procedure is correlated with what is called the energy dependence of the detector. In accordance with the stated requirements of IEC 61267, the standard radiation quality beams and irradiation conditions (RQRs) are the tools and techniques for calibrating diagnostic X-Ray instruments and detectors. The purpose of this work is to evaluate the behavior of the energy dependence of a detector fabricated from a zinc oxide (ZnO) nanofilm. A Pantak industrial X-ray equipment was used to generate the RQR radiation quality beams and test three ZnO detector samples. A 6430 sub-femto-ammeter, Keithley, was used to bias the ZnO detector and simultaneously perform the output readings. The results showed that the ZnO device has some increase in its sensitivity to the ionizing radiation as the X-ray effective energy decreases unlike other types of semiconductor electronic devices typically used as an X-ray detector. We can conclude that the ZnO device can be used as a diagnostic X-ray detector with an appropriate calibration. (author)

  5. Evaluation of the energy dependence of a zinc oxide nanofilm X-ray detector

    Energy Technology Data Exchange (ETDEWEB)

    Valenca, C.P.V., E-mail: claudia.cpvv@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife (Brazil); Silveira, M.A.L.; Macedo, M.A., E-mail: odecamm@gmail.com [Universidade Federal de Sergipe (UFSE), Sao Cristovao, SE (Brazil); Santos, L.A.P, E-mail: lasantos@scients.com.br [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2015-07-01

    International organizations of human health and radiation protection have recommended certain care for using of the X-ray as a diagnosis tool to avoid any type of radiological accident or overdose to the patient. This can be done assessing the parameters of the X-ray equipment and there are various types of detectors available for that: ionizing chamber, electronic semiconductor devices, etc. These detectors must be calibrated so that they can be used for any energy range and such a procedure is correlated with what is called the energy dependence of the detector. In accordance with the stated requirements of IEC 61267, the standard radiation quality beams and irradiation conditions (RQRs) are the tools and techniques for calibrating diagnostic X-Ray instruments and detectors. The purpose of this work is to evaluate the behavior of the energy dependence of a detector fabricated from a zinc oxide (ZnO) nanofilm. A Pantak industrial X-ray equipment was used to generate the RQR radiation quality beams and test three ZnO detector samples. A 6430 sub-femto-ammeter, Keithley, was used to bias the ZnO detector and simultaneously perform the output readings. The results showed that the ZnO device has some increase in its sensitivity to the ionizing radiation as the X-ray effective energy decreases unlike other types of semiconductor electronic devices typically used as an X-ray detector. We can conclude that the ZnO device can be used as a diagnostic X-ray detector with an appropriate calibration. (author)

  6. P2U-receptor mediated endothelium-dependent but nitric oxide-independent vascular relaxation

    DEFF Research Database (Denmark)

    Malmsjö, M; Edvinsson, L; Erlinge, D

    1998-01-01

    ) may also be involved. Dilator effects were studied in vitro by continuous recording of isomeric tension in cylindrical segments of rat blood vessels precontracted by noradrenaline (NA), in the presence of indomethacin (10 microM). 2. By screening different blood vessels in the rat we found that both...... carotid artery the dilatation was solely mediated by an endothelium-dependent NO mechanism, even at different resting tones (1 and 4 mN). 3. The N-nitro-L-arginine methyl ester (L-NAME)-resistant dilatation to ACh and ATP was further inhibited by the NO-scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1......-oxyl-3-oxide (PTIO), indicating L-NAME insensitive NO-synthesis. 4. In carotid arteries and mesenteric arteries at high resting tones (4 mN) the ATP-dilatation was totally inhibited by endothelium removal or L-NAME (10(-3) M). In mesenteric arteries at low resting tone (1 mN) the ATP, UTP (uridine...

  7. Substrate-dependent nitric oxide synthesis by secreted endoplasmic reticulum aminopeptidase 1 in macrophages.

    Science.gov (United States)

    Goto, Yoshikuni; Ogawa, Kenji; Nakamura, Takahiro J; Hattori, Akira; Tsujimoto, Masafumi

    2015-06-01

    In this study, we examined the role of aminopeptidases with reference to endoplasmic reticulum aminopeptidase 1 (ERAP1) in nitric oxide (NO) synthesis employing murine macrophage cell line RAW264.7 cells activated by lipopolysaccharide (LPS) and interferon (IFN)-γ and LPS-activated peritoneal macrophages derived from ERAP1 knockout mouse. When NO synthesis was measured in the presence of peptides having N-terminal Arg, comparative NO synthesis was seen with that measured in the presence of Arg. In the presence of an aminopeptidase inhibitor amastatin, NO synthesis in activated RAW264.7 cells was significantly decreased. These results suggest that aminopeptidases are involved in the NO synthesis in activated RAW264.7 cells. Subsequently, significant reduction of NO synthesis was observed in ERAP1 knockdown cells compared with wild-type cells. This reduction was rescued by exogenously added ERAP1. Furthermore, when peritoneal macrophages prepared from ERAP1 knockout mouse were employed, reduction of NO synthesis in knockout mouse macrophages was also attributable to ERAP1. In the presence of amastatin, further reduction was observed in knockout mouse-derived macrophages. Taken together, these results suggest that several aminopeptidases play important roles in the maximum synthesis of NO in activated macrophages in a substrate peptide-dependent manner and ERAP1 is one of the aminopeptidases involved in the NO synthesis. PMID:25577645

  8. Mitochondrial Sirt3 supports cell proliferation by regulating glutamine-dependent oxidation in renal cell carcinoma.

    Science.gov (United States)

    Choi, Jieun; Koh, Eunjin; Lee, Yu Shin; Lee, Hyun-Woo; Kang, Hyeok Gu; Yoon, Young Eun; Han, Woong Kyu; Choi, Kyung Hwa; Kim, Kyung-Sup

    2016-06-01

    Clear cell renal carcinoma (RCC), the most common malignancy arising in the adult kidney, exhibits increased aerobic glycolysis and low mitochondrial respiration due to von Hippel-Lindau gene defects and constitutive hypoxia-inducible factor-α expression. Sirt3 is a major mitochondrial deacetylase that mediates various types of energy metabolism. However, the role of Sirt3 as a tumor suppressor or oncogene in cancer depends on cell types. We show increased Sirt3 expression in the mitochondrial fraction of human RCC tissues. Sirt3 depletion by lentiviral short-hairpin RNA, as well as the stable expression of the inactive mutant of Sirt3, inhibited cell proliferation and tumor growth in xenograft nude mice, respectively. Furthermore, mitochondrial pyruvate, which was used for oxidation in RCC, might be derived from glutamine, but not from glucose and cytosolic pyruvate, due to depletion of mitochondrial pyruvate carrier and the relatively high expression of malic enzyme 2. Depletion of Sirt3 suppressed glutamate dehydrogenase activity, leading to impaired mitochondrial oxygen consumption. Our findings suggest that Sirt3 plays a tumor-progressive role in human RCC by regulating glutamine-derived mitochondrial respiration, particularly in cells where mitochondrial usage of cytosolic pyruvate is severely compromised. PMID:27114304

  9. Temperature dependence of dissolution rate of a lead oxide mass exchanger in lead–bismuth eutectic

    International Nuclear Information System (INIS)

    A Computational Fluid Dynamic (CFD) model of a lead oxide mass exchanger (PbO MX) was developed. The mass exchanger consisted of a packed bed of PbO spheres. The geometry was created using Discrete Elements Method (DEM) software while the meshing, the solving and the post-processing were done by the commercial CFD package CFX. The dissolution process was modeled by implementing in the code oxygen mass transfer through the boundary layer. The dissolution rate was then predicted for different temperatures. Experiments were also performed at the LBE material test loop known as the DELTA loop. Oxygen concentration at the outlet of the PbO MX was measured for different conditions using a potentiometric oxygen sensor and the dissolution rate was determined for five different temperatures. The experimental data were compared with the numerical model. The temperature dependence of the dissolution rate was then determined in terms of Sherwood number by fitting the simulation results while keeping constant Reynolds number. The results showed that the Sherwood number for PbO MX in flowing LBE varies with Sc0.323

  10. Chromium oxide nanoparticle-induced genotoxicity and p53-dependent apoptosis in human lung alveolar cells.

    Science.gov (United States)

    Senapati, Violet Aileen; Jain, Abhishek Kumar; Gupta, Govind Sharan; Pandey, Alok Kumar; Dhawan, Alok

    2015-10-01

    Chromium oxide (Cr2 O3 ) nanoparticles (NPs) are being increasingly used as a catalyst for aromatic compound manufacture, abrading agents and as pigments (e.g., Viridian). Owing to increased applications, it is important to study the biological effects of Cr2 O3 NPs on human health. The lung is one of the main exposure routes to nanomaterials; therefore, the present study was designed to determine the genotoxic and apoptotic effect of Cr2 O3 NPs in human lung epithelial cells (A549). The study also elucidated the molecular mechanism of its toxicity. Cr2 O3 NPs led to DNA damage, which was deduced by comet assay and cytokinesis block micronucleus assay. The damage could be mediated by the increased levels of reactive oxygen species. Further, the oxygen species led to a decrease in mitochondrial membrane potential and an increase in the ratio of BAX/Bcl-2 leading to mitochondria-mediated apoptosis induced by Cr2 O3 NPs, which ultimately leads to cell death. Hence, there is a need of regulations to be imposed in NP usage. The study provided insight into the caspase-dependent mechanistic pathway of apoptosis. PMID:26086747

  11. Time-dependent postirradiation oxidative chemical changes in dehydrated egg products

    International Nuclear Information System (INIS)

    Radiation-induced oxidative chemical changes in whole egg and egg yolk powder were followed in time after irradiation as a function of dose, dose rate, and storage atmosphere. In evacuated samples of whole egg powder the decay of lipid hydroperoxides (LOOH) was pseudo-first order (kappa = 0.088 day-1), while carotenoids did not decay at all. In the presence of air both lipid hydroperoxides and carotenoids decayed during postirradiation storage. The decay of LOOH could be treated by dispersive kinetics with the measure of dispersion, alpha = 0.51 +/- 0.05, independent of dose, and the effective lifetime tau inversely related to dose. The decay of carotenoids could also be treated by dispersive kinetics, with the values of alpha decreasing with increasing dose. The effective lifetimes of carotenoids did not depend on dose in samples irradiated in vacuum. In samples irradiated and stored in air the effective lifetimes decreased with dose, faster in egg yolk than in whole egg powder. The complex nature of postirradiation kinetics in solid food systems is discussed

  12. Shape-Dependent Surface Reactivity and Antimicrobial Activity of Nano-Cupric Oxide.

    Science.gov (United States)

    Gilbertson, Leanne M; Albalghiti, Eva M; Fishman, Zachary S; Perreault, François; Corredor, Charlie; Posner, Jonathan D; Elimelech, Menachem; Pfefferle, Lisa D; Zimmerman, Julie B

    2016-04-01

    Shape of engineered nanomaterials (ENMs) can be used as a design handle to achieve controlled manipulation of physicochemical properties. This tailored material property approach necessitates the establishment of relationships between specific ENM properties that result from such manipulations (e.g., surface area, reactivity, or charge) and the observed trend in behavior, from both a functional performance and hazard perspective. In this study, these structure-property-function (SPF) and structure-property-hazard (SPH) relationships are established for nano-cupric oxide (n-CuO) as a function of shape, including nanospheres and nanosheets. In addition to comparing these shapes at the nanoscale, bulk CuO is studied to compare across length scales. The results from comprehensive material characterization revealed correlations between CuO surface reactivity and bacterial toxicity with CuO nanosheets having the highest surface reactivity, electrochemical activity, and antimicrobial activity. While less active than the nanosheets, CuO nanoparticles (sphere-like shape) demonstrated enhanced reactivity compared to the bulk CuO. This is in agreement with previous studies investigating differences across length-scales. To elucidate the underlying mechanisms of action to further explain the shape-dependent behavior, kinetic models applied to the toxicity data. In addition to revealing different CuO material kinetics, trends in observed response cannot be explained by surface area alone. The compiled results contribute to further elucidate pathways toward controlled design of ENMs. PMID:26943499

  13. In Situ Study of Strain-Dependent Ion Conductivity of Stretchable Polyethylene Oxide Electrolyte

    Science.gov (United States)

    Kelly, Taylor; Ghadi, Bahar Moradi; Berg, Sean; Ardebili, Haleh

    2016-02-01

    There is a strong need in developing stretchable batteries that can accommodate stretchable or irregularly shaped applications including medical implants, wearable devices and stretchable electronics. Stretchable solid polymer electrolytes are ideal candidates for creating fully stretchable lithium ion batteries mainly due to their mechanical and electrochemical stability, thin-film manufacturability and enhanced safety. However, the characteristics of ion conductivity of polymer electrolytes during tensile deformation are not well understood. Here, we investigate the effects of tensile strain on the ion conductivity of thin-film polyethylene oxide (PEO) through an in situ study. The results of this investigation demonstrate that both in-plane and through-plane ion conductivities of PEO undergo steady and linear growths with respect to the tensile strain. The coefficients of strain-dependent ion conductivity enhancement (CSDICE) for in-plane and through-plane conduction were found to be 28.5 and 27.2, respectively. Tensile stress-strain curves and polarization light microscopy (PLM) of the polymer electrolyte film reveal critical insights on the microstructural transformation of stretched PEO and the potential consequences on ionic conductivity.

  14. Mitochondrial dependent oxidative stress in cell culture induced by laser radiation at 1265 nm.

    Science.gov (United States)

    Saenko, Yury V; Glushchenko, Eugenia S; Zolotovskii, Igor O; Sholokhov, Evgeny; Kurkov, Andrey

    2016-04-01

    Photodynamic therapy is the main technique applied for surface carcinoma treatment. This technique employs singlet oxygen generated via a laser excited photosensitizer as a main damaging agent. However, prolonged sensitivity to intensive light, relatively low tissue penetration by activating light the cost of photosensitizer (PS) administration can limit photodynamic therapy applications. Early was reported singlet oxygen generation without photosensitizer induced by a laser irradiation at the wavelength of 1250-1270 nm. Here, we study the dynamics of oxidative stress, DNA damage, changes of mitochondrial potential, and mitochondrial mass induced by a laser at 1265 nm have been studied in HCT-116 and CHO-K cells. Laser irradiation of HCT-116 and CHO-K cells has induced a dose-dependent cell death via increasing intracellular reactive oxygen species (ROS) concentration, increase of DNA damage, decrease of mitochondrial potential, and reduced glutathione. It has been shown that, along with singlet oxygen generation, the increase of the intracellular ROS concentration induced by mitochondrial damage contributes to the damaging effect of the laser irradiation at 1265 nm. PMID:26796703

  15. Temperature dependence of the rate of the catalytic oxidation of 1-hexene in the presence of neutral salts

    Energy Technology Data Exchange (ETDEWEB)

    Samokhvalova, A.I.; Enikolopov, N.S.; Karmilova, L.V.; Soloveva, A.B.

    1985-10-01

    This paper studies the temperature dependence of the observed rate constant lambda/sub 1/ in the oxidation of 1-hexene (for oxidation less than or equal to 20%) and the effect of the presence of neutral salts in the reaction system on this constant. The oxidation of 1-hexene was carried out in the presence of LiF in N,N-dimethylformide at 278-310 K. The reaction kinetics was studied by gas-liquid chromatography relative to the consumption of 1-hexene. The effective activation energy found indicates the transport nature of the steps determining the rate constant, while the dependence of the activation energy on the neutral salt concentration indicates the predominant role of ion-dipole

  16. Unravelling the dependence of hydrogen oxidation kinetics on the size of Pt nanoparticles by in operando nanoplasmonic temperature sensing

    DEFF Research Database (Denmark)

    Wettergren, Kristina; Hellman, Anders; Cavalca, Filippo Carlo;

    2015-01-01

    We use a noninvasive nanoscale optical-temperature measurement method based on localized surface plasmon resonance to investigate the particle size-dependence of the hydrogen oxidation reaction kinetics on model supported Pt nanocatalysts at atmospheric pressure in operando. With decreasing average...

  17. Temperature dependence of electric resistance of anodic oxide films on niobium base alloy NbTsU

    International Nuclear Information System (INIS)

    Electrical resistance of oxide coatings formed on the surface of the NbTsU niobium alloy in aqueous solutions of alkaline electrolytes is investigated. Some anomalies related to the conditions of coating formation are canceled in temperature dependences of electrical resistance. The values of activation energy of electroconducting processes for different temperature intervals are calculated

  18. Individual whey protein components influence lipid oxidation dependent on pH

    DEFF Research Database (Denmark)

    Horn, Anna Frisenfeldt; Nielsen, Nina Skall; Jacobsen, Charlotte

    In emulsions, lipid oxidation is expected to be initiated at the oil-water interface. The properties of the emulsifier used and the composition at the interface is therefore expected to be of great importance for the resulting oxidation. Previous studies have shown that individual whey protein...... affecting the preferential adsorption of whey protein components at the interface. The aim of the study was to compare lipid oxidation in 10% fish oil-in-water emulsions prepared with 1% whey protein having either a high concentration of α-lactalbumin, a high concentration of β-lactoglobulin or equal...... amounts of the two. Emulsions were prepared at pH4 and pH7. Emulsions were characterized by their droplet sizes, viscosities, and contents of proteins in the water phase. Lipid oxidation was assessed by PV and secondary volatile oxidation products. Results showed that pH greatly influenced the oxidative...

  19. Inducible nitric-oxide synthase attenuates vasopressin-dependent Ca2+ signaling in rat hepatocytes

    OpenAIRE

    Patel, S.; Gaspers, L. D.; Boucherie, S.; Memin, E.; Stellato, K. A.; Guillon, G; Combettes, L; Thomas, A P

    2002-01-01

    Increases in both Ca2+ and nitric oxide levels are vital for a variety of cellular processes; however, the interaction between these two crucial messengers is not fully understood. Here, we demonstrate that expression of inducible nitric-oxide synthase in hepatocytes, in response to inflammatory mediators, dramatically attenuates Ca2+ signaling by the inositol 1,4,5-trisphosphate-forming hormone, vasopressin. The inhibitory effects of induction were reversed by nitric oxide inhibitors and mim...

  20. The chloroplast small heat shock protein undergoes oxidation-dependent conformational changes and may protect plants from oxidative stress

    OpenAIRE

    Härndahl, Ulrika; Hall, Roberta Buffoni; Osteryoung, Katherine W.; Vierling, Elizabeth; Bornman, Janet F.; Sundby, Cecilia

    1999-01-01

    The nuclear-encoded chloroplast-localized Hsp21 is an oligomeric heat shock protein (Hsp), belonging to the protein family of small Hsps and α-crystallins. We have investigated the effects of high temperature and oxidation treatments on the structural properties of Hsp21, both in purified recombinant form and in transgenic Arabidopsis thaliana plants engineered to constitutively overexpress Hsp21. A conformational change was observed for the 300 kDa oligomeric Hsp21 protein during moderate he...

  1. Tumor necrosis factor alpha augments nitric oxide-dependent macrophage cytotoxicity against Entamoeba histolytica by enhanced expression of the nitric oxide synthase gene.

    OpenAIRE

    Lin, J. Y.; Seguin, R; K. Keller; Chadee, K

    1994-01-01

    Nitric oxide (NO measured as nitrite, NO2-) is the major effector molecule produced by activated macrophages for in vitro cytotoxicity against Entamoeba histolytica trophozoites. In this study, we determine whether tumor necrosis factor alpha (TNF-alpha) produced by activated bone marrow-derived macrophages (BMM) is involved in the induction of the inducible NO synthase gene (mac-NOS) for NO-dependent amebicidal activity. TNF-alpha alone did not directly induce macrophage NO2- production to k...

  2. Synthesis, Characterization and Shape-Dependent Catalytic CO Oxidation Performance of Ruthenium Oxide Nanomaterials: Influence of Polymer Surfactant

    Directory of Open Access Journals (Sweden)

    Antony Ananth

    2015-08-01

    Full Text Available Ruthenium oxide nano-catalysts supported on mesoporous γ-Al2O3 have been prepared by co-precipitation method and tested for CO oxidation. The effect of polyethylene glycol (PEG on the properties of the catalyst was studied. Addition of the PEG surfactant acted as a stabilizer and induced a change in the morphology of ruthenium oxide from spherical nanoparticles to one-dimensional nanorods. Total CO conversion was measured as a function of morphology at 175 °C and 200 °C with 1.0 wt.% loading for PEG-stabilized and un-stabilized catalysts, respectively. Conversion routinely increased with temperature but in each case, the PEG-stabilized catalyst exhibited a notably higher catalytic activity as compared to the un-stabilized equivalent. It can be assumed that the increase in the activity is due to the changes in porosity, shape and dispersion of the catalyst engendered by the use of PEG.

  3. Control of the neurovascular coupling by nitric oxide-dependent regulation of astrocytic Ca2+ signaling

    Directory of Open Access Journals (Sweden)

    Manuel Francisco Muñoz

    2015-03-01

    Full Text Available Neuronal activity must be tightly coordinated with blood flow to keep proper brain function, which is achieved by a mechanism known as neurovascular coupling. Then, an increase in synaptic activity leads to a dilation of local parenchymal arterioles that matches the enhanced metabolic demand. Neurovascular coupling is orchestrated by astrocytes. These glial cells are located between neurons and the microvasculature, with the astrocytic endfeet ensheathing the vessels, which allows fine intercellular communication. The neurotransmitters released during neuronal activity reach astrocytic receptors and trigger a Ca2+ signaling that propagates to the endfeet, activating the release of vasoactive factors and arteriolar dilation. The astrocyte Ca2+ signaling is coordinated by gap junction channels and hemichannels formed by connexins (Cx43 and Cx30 and channels formed by pannexins (Panx-1. The neuronal activity-initiated Ca2+ waves are propagated among neighboring astrocytes directly via gap junctions or through ATP release via connexin hemichannels or pannexin channels. In addition, Ca2+ entry via connexin hemichannels or pannexin channels may participate in the regulation of the astrocyte signaling-mediated neurovascular coupling. Interestingly, nitric oxide (NO can activate connexin hemichannel by S-nitrosylation and the Ca2+-dependent NO-synthesizing enzymes endothelial NO synthase (eNOS and neuronal NOS (nNOS are expressed in astrocytes. Therefore, the astrocytic Ca2+ signaling triggered in neurovascular coupling may activate NO production, which, in turn, may lead to Ca2+ influx through hemichannel activation. Furthermore, NO release from the hemichannels located at astrocytic endfeet may contribute to the vasodilation of parenchymal arterioles. In this review, we discuss the mechanisms involved in the regulation of the astrocytic Ca2+ signaling that mediates neurovascular coupling, with a special emphasis in the possible participation of NO in

  4. Nitric oxide regulates input specificity of long-term depression and context dependence of cerebellar learning.

    Directory of Open Access Journals (Sweden)

    Hideaki Ogasawara

    2007-01-01

    Full Text Available Recent studies have shown that multiple internal models are acquired in the cerebellum and that these can be switched under a given context of behavior. It has been proposed that long-term depression (LTD of parallel fiber (PF-Purkinje cell (PC synapses forms the cellular basis of cerebellar learning, and that the presynaptically synthesized messenger nitric oxide (NO is a crucial "gatekeeper" for LTD. Because NO diffuses freely to neighboring synapses, this volume learning is not input-specific and brings into question the biological significance of LTD as the basic mechanism for efficient supervised learning. To better characterize the role of NO in cerebellar learning, we simulated the sequence of electrophysiological and biochemical events in PF-PC LTD by combining established simulation models of the electrophysiology, calcium dynamics, and signaling pathways of the PC. The results demonstrate that the local NO concentration is critical for induction of LTD and for its input specificity. Pre- and postsynaptic coincident firing is not sufficient for a PF-PC synapse to undergo LTD, and LTD is induced only when a sufficient amount of NO is provided by activation of the surrounding PFs. On the other hand, above-adequate levels of activity in nearby PFs cause accumulation of NO, which also allows LTD in neighboring synapses that were not directly stimulated, ruining input specificity. These findings lead us to propose the hypothesis that NO represents the relevance of a given context and enables context-dependent selection of internal models to be updated. We also predict sparse PF activity in vivo because, otherwise, input specificity would be lost.

  5. Brain BDNF levels are dependent on cerebrovascular endothelium-derived nitric oxide.

    Science.gov (United States)

    Banoujaafar, Hayat; Monnier, Alice; Pernet, Nicolas; Quirié, Aurore; Garnier, Philippe; Prigent-Tessier, Anne; Marie, Christine

    2016-09-01

    Scientific evidence continues to demonstrate a link between endothelial function and cognition. Besides, several studies have identified a complex interplay between nitric oxide (NO) and brain-derived neurotrophic factor (BDNF), a neurotrophin largely involved in cognition. Therefore, this study investigated the link between cerebral endothelium-derived NO and BDNF signaling. For this purpose, levels of BDNF and the phosphorylated form of endothelial NO synthase at serine 1177 (p-eNOS) were simultaneously measured in the cortex and hippocampus of rats subjected to either bilateral common carotid occlusion (n = 6), physical exercise (n = 6) or a combination of both (n = 6) as experimental approaches to modulate flow-induced NO production by the cerebrovasculature. Tropomyosin-related kinase type B (TrkB) receptors and its phosphorylated form at tyrosine 816 (p-TrkB) were also measured. Moreover, we investigated BDNF synthesis in brain slices exposed to the NO donor glyceryl trinitrate. Our results showed increased p-eNOS and BDNF levels after exercise and decreased levels after vascular occlusion as compared to corresponding controls, with a positive correlation between changes in p-eNOS and BDNF (r = 0.679). Exercise after vascular occlusion did not change levels of these proteins. Gyceryl trinitrate increased proBDNF and BDNF levels in brain slices, thus suggesting a possible causal relationship between NO and BDNF. Moreover, vascular occlusion, like exercise, resulted in increased TrkB and p-TrkB levels, whereas no change was observed with the combination of both. These results suggest that brain BDNF signaling may be dependent on cerebral endothelium-derived NO production. PMID:27306299

  6. Nitrite Regulates Hypoxic Vasodilation via Myoglobin–Dependent Nitric Oxide Generation

    Science.gov (United States)

    Totzeck, Matthias; Hendgen-Cotta, Ulrike B.; Luedike, Peter; Berenbrink, Michael; Klare, Johann P.; Steinhoff, Heinz-Juergen; Semmler, Dominik; Shiva, Sruti; Williams, Daryl; Kipar, Anja; Gladwin, Mark T.; Schrader, Juergen; Kelm, Malte; Cossins, Andrew R.; Rassaf, Tienush

    2012-01-01

    Background Hypoxic vasodilation is a physiological response to low oxygen (O2) tension that increases blood supply to match metabolic demands. While this response has been characterized for more than 100 years, the underlying hypoxic sensing and effector signaling mechanisms remain uncertain. We have shown that deoxygenated myoglobin (deoxyMb) in the heart can reduce nitrite to nitric oxide (NO˙) and thereby contribute to cardiomyocyte NO˙ signaling during ischemia. Based on recent observations that Mb is expressed in the vasculature of hypoxia-tolerant fish, we hypothesized that endogenous nitrite may contribute to physiological hypoxic vasodilation via reactions with vascular Mb to form NO˙. Methods and Results We here show that Mb is expressed in vascular smooth muscle and contributes significantly to nitrite-dependent hypoxic vasodilation in vivo and ex vivo. The generation of NO˙ from nitrite reduction by deoxyMb activates canonical soluble guanylate cyclase (sGC)/cyclic guanosine monophosphate (cGMP) signaling pathways. In vivo and ex vivo vasodilation responses, the reduction of nitrite to NO˙ and the subsequent signal transduction mechanisms were all significantly impaired in mice without myoglobin (Mb−/−). Hypoxic vasodilation studies in Mb, endothelial and inducible NO synthase knockout models (eNOS−/−, iNOS−/−) suggest that only Mb contributes to systemic hypoxic vasodilatory responses in mice. Conclusions Endogenous nitrite is a physiological effector of hypoxic vasodilation. Its reduction to NO˙ via the heme globin Mb enhances blood flow and matches O2 supply to increased metabolic demands under hypoxic conditions. PMID:22685116

  7. Substrate dependent self-organization of mesoporous cobalt oxide nanowires with remarkable pseudocapacitance

    KAUST Repository

    Baby, Rakhi Raghavan

    2012-05-09

    A scheme of current collector dependent self-organization of mesoporous cobalt oxide nanowires has been used to create unique supercapacitor electrodes, with each nanowire making direct contact with the current collector. The fabricated electrodes offer the desired properties of macroporosity to allow facile electrolyte flow, thereby reducing device resistance and nanoporosity with large surface area to allow faster reaction kinetics. Co 3O 4 nanowires grown on carbon fiber paper collectors self-organize into a brush-like morphology with the nanowires completely surrounding the carbon microfiber cores. In comparison, Co 3O 4 nanowires grown on planar graphitized carbon paper collectors self-organize into a flower-like morphology. In three electrode configuration, brush-like and flower-like morphologies exhibited specific capacitance values of 1525 and 1199 F/g, respectively, at a constant current density of 1 A/g. In two electrode configuration, the brush-like nanowire morphology resulted in a superior supercapacitor performance with high specific capacitances of 911 F/g at 0.25 A/g and 784 F/g at 40 A/g. In comparison, the flower-like morphology exhibited lower specific capacitance values of 620 F/g at 0.25 A/g and 423 F/g at 40 A/g. The Co 3O 4 nanowires with brush-like morphology exhibited high values of specific power (71 kW/kg) and specific energy (81 Wh/kg). Maximum energy and power densities calculated for Co 3O 4 nanowires with flower-like morphology were 55 Wh/kg and 37 kW/kg respectively. Both electrode designs exhibited excellent cycling stability by retaining ∼91-94% of their maximum capacitance after 5000 cycles of continuous charge-discharge. © 2012 American Chemical Society.

  8. Regulating the stability of 2D crystal structures using an oxidation state-dependent molecular conformation.

    Science.gov (United States)

    Hill, Jonathan P; Wakayama, Yutaka; Schmitt, Wolfgang; Tsuruoka, Tohru; Nakanishi, Takashi; Zandler, Melvin L; McCarty, Amy L; D'Souza, Francis; Milgrom, Lionel R; Ariga, Katsuhiko

    2006-06-14

    The oxidation state of the phenol-substituted porphyrin TDtBHPP is coupled with its structure so that its 2-electron oxidation leads to a coplanarization of the molecule and a substantial stabilization of its surface self-assembled structures adsorbed at metal substrates. PMID:16733566

  9. LET Dependence of Gate Oxide Breakdown of SiC MOS Capacitors due to Single Heavy Ion Irradiation

    OpenAIRE

    Deki, Manato; Makino, Takahiro; Tomita, Takuro; Hashimoto, Shuichi; Kojima, Kazutoshi; Oshima, Takeshi

    2013-01-01

    The currents through the gate oxide of the 4H-Silicon Carbide (SiC) Metal Oxide Semiconductor (MOS) capacitors at the accumulate condition were measured during heavy ion irradiation. Linear Energy Transfer (LET) dependence of the critical electric field (Ecr) at which the dielectric breakdown occurs in 4H-SiC MOS capacitors was studied. It was revealed that Ecr decreases with increasing LET. Ecr for SiC became higher than that for Si. This suggests that SiC MOS devices are promising candidate...

  10. LET dependence of gate oxide breakdown of SiC-MOS capacitors due to single heavy ion irradiation

    International Nuclear Information System (INIS)

    The currents through the gate oxide of the 4H-Silicon Carbide (SiC) Metal Oxide Semiconductor (MOS) capacitors at the accumulate condition were measured during heavy ion irradiation. Linear Energy Transfer (LET) dependence of the critical electric field (Ecr) at which the dielectric breakdown occurs in 4H-SiC MOS capacitors was studied. It was revealed that Ecr decreases with increasing LET. Ecr for SiC became higher than that for Si. This suggests that SiC MOS devices are promising candidates for high SEGR resistant devices. (author)

  11. Inducible nitric-oxide synthase attenuates vasopressin-dependent Ca2+ signaling in rat hepatocytes.

    Science.gov (United States)

    Patel, Sandip; Gaspers, Lawrence D; Boucherie, Sylviane; Memin, Elisabeth; Stellato, Kerri Anne; Guillon, Gilles; Combettes, Laurent; Thomas, Andrew P

    2002-09-13

    Increases in both Ca(2+) and nitric oxide levels are vital for a variety of cellular processes; however, the interaction between these two crucial messengers is not fully understood. Here, we demonstrate that expression of inducible nitric-oxide synthase in hepatocytes, in response to inflammatory mediators, dramatically attenuates Ca(2+) signaling by the inositol 1,4,5-trisphosphate-forming hormone, vasopressin. The inhibitory effects of induction were reversed by nitric oxide inhibitors and mimicked by prolonged cyclic GMP elevation. Induction was without effect on Ca(2+) signals in response to AlF(4)(-) or inositol 1,4,5-trisphosphate, indicating that phospholipase C activation and release of Ca(2+) from inositol 1,4,5-trisphosphate-sensitive Ca(2+) stores were not targets for nitric oxide inhibition. Vasopressin receptor levels, however, were dramatically reduced in induced cultures. Our data provide a possible mechanism for hepatocyte dysfunction during chronic inflammation. PMID:12097323

  12. Puerarin activates endothelial nitric oxide synthase through estrogen receptor-dependent PI3-kinase and calcium-dependent AMP-activated protein kinase

    International Nuclear Information System (INIS)

    The cardioprotective properties of puerarin, a natural product, have been attributed to the endothelial nitric oxide synthase (eNOS)-mediated production of nitric oxide (NO) in EA.hy926 endothelial cells. However, the mechanism by which puerarin activates eNOS remains unclear. In this study, we sought to identify the intracellular pathways underlying eNOS activation by puerarin. Puerarin induced the activating phosphorylation of eNOS on Ser1177 and the production of NO in EA.hy926 cells. Puerarin-induced eNOS phosphorylation required estrogen receptor (ER)-mediated phosphatidylinositol 3-kinase (PI3K)/Akt signaling and was reversed by AMP-activated protein kinase (AMPK) and calcium/calmodulin-dependent kinase II (CaMKII) inhibition. Importantly, puerarin inhibited the adhesion of tumor necrosis factor (TNF)-α-stimulated monocytes to endothelial cells and suppressed the TNF-α induced expression of intercellular cell adhesion molecule-1. Puerarin also inhibited the TNF-α-induced nuclear factor-κB activation, which was attenuated by pretreatment with NG-nitro-L-arginine methyl ester, a NOS inhibitor. These results indicate that puerarin stimulates eNOS phosphorylation and NO production via activation of an estrogen receptor-mediated PI3K/Akt- and CaMKII/AMPK-dependent pathway. Puerarin may be useful for the treatment or prevention of endothelial dysfunction associated with diabetes and cardiovascular disease. -- Highlights: ► Puerarin induced the phosphorylation of eNOS and the production of NO. ► Puerarin activated eNOS through ER-dependent PI3-kinase and Ca2+-dependent AMPK. ► Puerarin-induced NO was involved in the inhibition of NF-kB activation. ► Puerarin may help for prevention of vascular dysfunction and diabetes.

  13. Age-dependent oxidative stress-induced DNA damage in Down's lymphocytes

    International Nuclear Information System (INIS)

    The aim of the present study was to investigate the oxidative status of lymphocytes from children (n = 7) and adults (n = 18) with Down's syndrome (DS). The basal oxidative condition, the vulnerability to in vitro hydrogen peroxide exposure, and the repair capacity were measured by means of the damage-specific alkaline comet assay. Significantly and age-independently elevated numbers of single strand breaks and oxidized bases (pyrimidines and purines) were found in the nuclear DNA of the lymphocytes in the DS group in the basal condition. These results may support the role of an increased level of endogenous oxidative stress in DS and are similar to those previously demonstrated in Alzheimer's disease. In the in vitro oxidative stress-induced state, a markedly higher extent of DNA damage was observed in DS children as compared with age- and gender-matched healthy controls, suggesting that young trisomic lymphocytes are more sensitive to oxidative stress than normal ones. However, the repair ability itself was not found to be deteriorated in either DS children or DS adults

  14. Dose-dependent genotoxicity of copper oxide nanoparticles stimulated by reactive oxygen species in human lung epithelial cells.

    Science.gov (United States)

    Akhtar, Mohammad Javed; Kumar, Sudhir; Alhadlaq, Hisham A; Alrokayan, Salman A; Abu-Salah, Khalid M; Ahamed, Maqusood

    2016-05-01

    Copper oxide nanoparticles (CuO NPs) are of great interest in nanoscience and nanotechnology because of their broad industrial and commercial applications. Therefore, toxicity of CuO NPs needs to be thoroughly understood. The aim of this study was to investigate the cytotoxicity, genotoxicity, and oxidative stress induced by CuO NPs in human lung epithelial (A549) cells. CuO NPs were synthesized by solvothermal method and the size of NPs measured under transmission electron microscopy (TEM) was found to be around 23 nm. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) and lactate dehydrogenase (LDH) assays showed that CuO NPs (5-15 µg/ml) exert cytotoxicity in A549 cells in a dose-dependent manner. Comet assay suggested concentration-dependent induction of DNA damage due to the exposure to CuO NPs. The comet tail moment was 27% at 15 µg/ml of CuO NPs, whereas it was 5% in control (p CuO NPs induced micronuclei (MN) in A549 cells dose dependently. The frequency of MN was 25/10(3) cells at 15 µg/ml of CuO NPs, whereas it was 2/10(3) cells for control. CuO NPs were also found to induce oxidative stress in a concentration-dependent manner, which was indicated by induction of reactive oxygen species (ROS) and lipid peroxidation along with glutathione depletion. Moreover, MN induction and DNA damage were significantly correlated with ROS (R(2) = 0.937 for ROS vs. olive tail moment, and R(2) = 0.944 for ROS vs. MN). Taken together, this study suggested that CuO NPs induce genotoxicity in A549 cells, which is likely to be mediated through ROS generation and oxidative stress. PMID:24311626

  15. Linking diffusion kinetics to defect electronic structure in metal oxides: Charge-dependent vacancy diffusion in alumina

    International Nuclear Information System (INIS)

    We study the diffusion of charged vacancies in α-Al2O3 crystal using the first-principles calculation method. We predict that the migration energy for vacancy diffusion strongly depends on the charge state of the vacancy involved. Importantly, we reveal that this charge-dependent vacancy diffusion is directly related to the electron occupancy and energy level change of the defect states of the charged vacancy in alumina. Hence, our study establishes a direct link between the diffusion kinetics and electronic structure of metal oxides

  16. Coverage dependent reaction of yttrium on silicon and the oxidation of yttrium silicide investigated by x-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    The reaction of yttrium (Y) on (001) silicon (Si) with low temperature annealing is investigated for different coverages of Y using in situ x-ray photoelectron spectroscopy. The authors have also performed oxidation studies for Y on Si in the formation of yttrium silicate by a two-step process. This consists of an ex situ oxidation of Y-Si film, which is formed from low temperature annealing in vacuum. These films were then probed with depth profiling x-ray photoelectron spectroscopy. They report on three general reaction phases of Y on Si that are coverage dependent. Different coverages show differences in Si mixing and selective ultrahigh vacuum oxidation. They also report on the self-limiting formation of yttrium silicate at room temperature and low annealing temperature, which is insensitive to the annealing ambient. They also highlight the importance of oxygen partial pressure in both initial silicate formation and the extent of oxidation at different annealing temperatures. Finally, the authors also show that a high oxygen diffusion barrier prevents the oxidation of the entire Y-Si film

  17. The dependence of the oxidation behaviour of 20%Cr austenitic steels on their silicon content

    International Nuclear Information System (INIS)

    The role of silicon in the oxidation of a series of 20%Cr/25%Ni/Nb-stabilised steels containing silicon in the range 0 to 2.25 wt.%. has been explored. Oxidation tests have been performed in thermobalances at 1173K (900oC) in a CO2-based gas at 1 atmosphere total pressure for exposure periods extending to 1.12 x 106s (310h). The oxidation kinetics were parabolic in all cases with a rate constant that achieved a minimum value in alloys containing ∼ 0.6 wt.% silicon. This minimum was associated with the development of a thin silicon-rich interlayer (presumed to be silica) between the chromia and steel. It is suggested that the growth of the chromia layer was controlled by the diffusion of chromium ions through the thickening silica interlayer. At higher alloy silicon levels, the thicker silica interlayer tended to be fragmented and the overall oxidation resistance was reduced. By contrast, the extent of oxide spallation on cooling was least in the silicon-free and dilute alloys and increased progressively with increasing silicon levels. It is considered that although the intrinsic adherence of the chromia was increased by the presence of a silica interlayer, interfacial crack formation within this layer became favoured as the thickness of the silica increased. (author)

  18. Enhanced Strain-Dependent Electrical Resistance of Polyurethane Composites with Embedded Oxidized Multiwalled Carbon Nanotube Networks

    Directory of Open Access Journals (Sweden)

    R. Benlikaya

    2013-01-01

    Full Text Available The effect of different chemical oxidation of multiwalled carbon nanotubes with H2O2, HNO3, and KMnO4 on the change of electrical resistance of polyurethane composites with embedded oxidized nanotube networks subjected to elongation and bending has been studied. The testing has shown about twenty-fold increase in the electrical resistance for the composite prepared from KMnO4 oxidized nanotubes in comparison to the composites prepared from the pristine and other oxidized nanotubes. The evaluated sensitivity of KMnO4 treated composite in terms of the gauge factor increases with strain to nearly 175 at the strain 11%. This is a substantial increase, which ranks the composite prepared from KMnO4 oxidized nanotubes among materials as strain gauges with the highest electromechanical sensitivity. The observed differences in electromechanical properties of the composites are discussed on basis of their structure which is examined by the measurements of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscope. The possible practical use of the composites is demonstrated by monitoring of elbow joint flexion during two different physical exercises.

  19. Diameter dependence of the void formation in the oxidation of nickel nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Y; Chim, W K [NUS Graduate School for Integrative Sciences and Engineering, 28 Medical Drive, 117456 (Singapore); Chiam, S Y, E-mail: elecwk@nus.edu.sg [Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 3 Research Link, 117602 (Singapore)

    2011-06-10

    In this work, we show how the vacancy diffusion length scale must be considered, in the context of the diameter of a nanowire, when utilizing the Kirkendall phenomenon in the fabrication of metal oxide nanotubes starting from metal nanowires. We find that the diameter of the nanowire relative to the diffusion length scale of the vacancy will affect greatly the type of voids that can be generated. By using a larger diameter nickel nanowire, we show that segmented heterojunction void formation can be avoided and that the resulting structure will serve as a precursory 'template' for subsequent oxidation processes at high temperatures. In doing so, we can prevent the formation of bamboo-like structures and obtain uniform nickel oxide nanotubes through direct oxidation that has proven to be difficult previously. The result from this work is also significant as the interplay of vacancy diffusion length and nanostructure dimension is important in the oxidation of other types of metal nanostructures, especially when void formation and the Kirkendall effect are involved.

  20. Diameter dependence of the void formation in the oxidation of nickel nanowires

    International Nuclear Information System (INIS)

    In this work, we show how the vacancy diffusion length scale must be considered, in the context of the diameter of a nanowire, when utilizing the Kirkendall phenomenon in the fabrication of metal oxide nanotubes starting from metal nanowires. We find that the diameter of the nanowire relative to the diffusion length scale of the vacancy will affect greatly the type of voids that can be generated. By using a larger diameter nickel nanowire, we show that segmented heterojunction void formation can be avoided and that the resulting structure will serve as a precursory 'template' for subsequent oxidation processes at high temperatures. In doing so, we can prevent the formation of bamboo-like structures and obtain uniform nickel oxide nanotubes through direct oxidation that has proven to be difficult previously. The result from this work is also significant as the interplay of vacancy diffusion length and nanostructure dimension is important in the oxidation of other types of metal nanostructures, especially when void formation and the Kirkendall effect are involved.

  1. Environment-dependent photochromism of silver nanoparticles interfaced with metal-oxide films

    Science.gov (United States)

    Fu, Shencheng; Sun, Shiyu; Zhang, Xintong; Zhang, Cen; Zhao, Xiaoning; Liu, Yichun

    2015-12-01

    Different metal-oxide films were fabricated by radio frequency magnetron sputtering. Further, a layer of silver nanoparticles (NPs) was deposited on the surface of the substrate by physical sputtering. Photochromism of the silver/metal-oxide nanocomposite films were investigated in situ under the irradiation of a linearly-polarized green laser beam (532 nm). Silver NPs were found to be easily photo-dissolved on the n-type metal-oxide films. By changing experimental conditions, it was also verified that both oxygen and humidity accelerate the photochromism of silver NPs. The corresponding micro-mechanism on charge separation and Ag+-ions mobility was also discussed. These results provided theoretical basis for the application of silver NPs in biological, chemical and medical areas.

  2. Sex-dependent mitochondrial respiratory impairment and oxidative stress in a rat model of neonatal hypoxic-ischemic encephalopathy.

    Science.gov (United States)

    Demarest, Tyler G; Schuh, Rosemary A; Waddell, Jaylyn; McKenna, Mary C; Fiskum, Gary

    2016-06-01

    Increased male susceptibility to long-term cognitive deficits is well described in clinical and experimental studies of neonatal hypoxic-ischemic encephalopathy. While cell death signaling pathways are known to be sexually dimorphic, a sex-dependent pathophysiological mechanism preceding the majority of secondary cell death has yet to be described. Mitochondrial dysfunction contributes to cell death following cerebral hypoxic-ischemia (HI). Several lines of evidence suggest that there are sex differences in the mitochondrial metabolism of adult mammals. Therefore, this study tested the hypothesis that brain mitochondrial respiratory impairment and associated oxidative stress is more severe in males than females following HI. Maximal brain mitochondrial respiration during oxidative phosphorylation was two-fold more impaired in males following HI. The endogenous antioxidant glutathione was 30% higher in the brain of sham females compared to males. Females also exhibited increased glutathione peroxidase (GPx) activity following HI injury. Conversely, males displayed a reduction in mitochondrial GPx4 protein levels and mitochondrial GPx activity. Moreover, a 3-4-fold increase in oxidative protein carbonylation was observed in the cortex, perirhinal cortex, and hippocampus of injured males, but not females. These data provide the first evidence for sex-dependent mitochondrial respiratory dysfunction and oxidative damage, which may contribute to the relative male susceptibility to adverse long-term outcomes following HI. Lower basal GSH levels, lower post-hypoxic mitochondrial glutathione peroxidase (mtGPx) activity, and mitochondrial glutathione peroxidase 4 (mtGPx4) protein levels may contribute to the susceptibility of the male brain to oxidative damage and mitochondrial dysfunction following neonatal hypoxic-ischemia (HI). Treatment of male pups with acetyl-L-carnitine (ALCAR) protects against the loss of mtGPx activity, mtGPx4 protein, and increases in protein

  3. Enhanced Removal of Biogenic Hydrocarbons in Power Plant Plumes Constrains the Dependence of Atmospheric Hydroxyl Concentrations on Nitrogen Oxides

    Science.gov (United States)

    De Gouw, J. A.; Trainer, M.; Parrish, D. D.; Brown, S. S.; Edwards, P.; Gilman, J.; Graus, M.; Hanisco, T. F.; Kaiser, J.; Keutsch, F. N.; Kim, S. W.; Lerner, B. M.; Neuman, J. A.; Pollack, I. B.; Roberts, J. M.; Ryerson, T. B.; Veres, P. R.; Warneke, C.; Wolfe, G.

    2015-12-01

    Hydroxyl (OH) radicals in the atmosphere provide one of the main chemical mechanisms for the removal of trace gases. OH plays a central role in determining the atmospheric lifetime and radiative forcing of greenhouse gases like methane. OH also plays a major role in the oxidation of organic trace gases, which can lead to formation of secondary pollutants such as ozone and PM2.5. Due to its very short atmospheric lifetime of seconds or less, OH concentrations are extremely variable in space and time, which makes measurements and their interpretation very challenging. Several recent measurements have yielded higher than expected OH concentrations. To explain these would require the existence of unidentified, radical recycling processes, but issues with the measurements themselves are also still being discussed. During the NOAA airborne SENEX study in the Southeast U.S., the biogenic hydrocarbons isoprene and monoterpenes were consistently found to have lower mixing ratios in air masses with enhanced nitrogen oxides from power plants. We attribute this to faster oxidation rates of biogenic hydrocarbons due to increased concentrations of OH in the power plant plumes. Measurements at different downwind distances from the Scherer and Harllee Branch coal-fired power plants near Atlanta are used to constrain the dependence of OH on nitrogen oxides. It is found that OH concentrations were highest at nitrogen dioxide concentrations of 1-2 ppbv and decreased at higher and at lower concentrations. These findings agree with the expected dependence of OH on nitrogen oxide concentrations, but do not appear to be consistent with the reports in the literature that have shown high OH concentrations in regions of the atmosphere with high biogenic emissions and low NOx concentrations that would require unidentified radical recycling processes to be explained.

  4. Hepatic calcium efflux during cytochrome P-450-dependent drug oxidations at the endoplasmic reticulum in intact liver.

    Science.gov (United States)

    Sies, H; Graf, P; Estrela, J M

    1981-06-01

    During metabolism of (type I) drugs by cytochrome P-450-dependent monooxygenase of the endoplasmic reticulum, the NADPH/NADP+ ratio in rat liver selectively decreases to approximately one-half of the control values, whereas the NADH/NAD+ ratio remains practically unaffected [Sies, H. & Brauser, B. (1970) Eur. J. Biochem. 15, 521-540]. In view of the observations with isolated mitochondria [Lehninger, A. L., Vercesi, A. & Bababunmi, E. A. (1978) Proc. Natl. Acad. Sci. USA 75, 1690-1694] of stimulated Ca2+ efflux upon nicotinamide nucleotide oxidation, the selective oxidation of NADPH in cytosol and mitochondria during drug oxidations was considered a useful experimental tool for the determination of whether the oxidation of NADPH or of NADH is responsible for Ca2+ efflux. With perfused livers from phenobarbital-treated rats, Ca2+ efflux was demonstrated, amounting to 8 nmol/min per gram of liver (wet weight), with aminopyrine, ethylmorphine, or hexobarbital as drug substrates. Drug-associated Ca2+ release was diminished when the inhibitor metyrapone was also present, or when drug oxidation was suppressed during N2 anoxia or in the presence of antimycin A in livers from fasted rats. Ca2+ efflux was elicited also by infusion of the thiol oxidant diamide, and by t-butyl hydroperoxide. However whereas Ca2+ efflux elicited by these compounds was restricted upon addition of the thiol dithioerythritol, there was little, if any, sensitivity of the drug-associated Ca2+ efflux to the thiol. Further mitochondrial oxidation of NADPH by addition of ammonium chloride had no effect on drug-associated Ca2+ efflux. Prior addition of the alpha-agonist phenylephrine suppressed the Ca2+ release by drug addition. While the molecular mechanism involved in Ca2+ efflux from liver mitochondria and from hepatocytes as well as the regulatory significance are not yet known, it is concluded from the present experiments that in case of nicotinamide nucleotide-linked Ca2+ efflux the oxidation of

  5. Study on the Size-Dependent Oxidation Reaction Kinetics of Nanosized Zinc Sulfide

    Directory of Open Access Journals (Sweden)

    Qing-Shan Fu

    2014-01-01

    Full Text Available Numerous oxidation problems of nanoparticles are often involved during the preparation and application of nanomaterials. The oxidation rate of nanomaterials is much faster than bulk materials due to nanoeffect. Nanosized zinc sulfide (nano-ZnS and oxygen were chosen as a reaction system. The influence regularities were discussed and the influence essence was elucidated theoretically. The results indicate that the particle size can remarkably influence the oxidation reaction kinetics. The rate constant and the reaction order increase, while the apparent activation energy and the preexponential factor decrease with the decreasing particle size. Furthermore, the logarithm of rate constant, the apparent activation energy and the logarithm of preexponential factor are linearly related to the reciprocal of particle diameter, respectively. The essence is that the rate constant is influenced by the combined effect of molar surface energy and molar surface entropy, the reaction order by the molar surface area, the apparent activation energy, by the molar surface energy, and the preexponential factor by the molar surface entropy. The influence regularities and essence can provide theoretical guidance to solve the oxidation problems involved in the process of preparation and application of nanomaterials.

  6. Solvent-dependent regioselective oxidation of trans-chalcones using aqueous hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Wang; Jiabin, Yang; Lushen, Li, E-mail: jimin@seu.edu.cn [Southeast University, Nanjing (China). School of Biological Science and Medical Engineering; Jin, Cai; Chunlong, Sun; Min, Ji [Southeast University, Nanjing (China). School of Chemistry and Chemical Engineering

    2013-03-15

    A novel method for regioselective oxidation of trans-chalcones with hydrogen peroxide in acetonitrile to afford cinnamic acids is reported. Only trans-b-arylacrylic acids were observed. A wide range of functionalized products can be effectively produced from various chalcones in good to excellent yields. (author)

  7. Endothelium dependent hyperpolarization-type relaxation compensates for attenuated nitric oxide-mediated responses in subcutaneous arteries of diabetic patients.

    Science.gov (United States)

    Mokhtar, Siti Safiah; Vanhoutte, Paul M; Leung, Susan Wai Sum; Yusof, Mohd Imran; Wan Sulaiman, Wan Azman; Mat Saad, Arman Zaharil; Suppian, Rapeah; Rasool, Aida Hanum Ghulam

    2016-02-29

    Diabetes impairs endothelium-dependent relaxations. The present study evaluated the contribution of different endothelium-dependent relaxing mechanisms to the regulation of vascular tone in subcutaneous blood vessels of humans with Type 2 diabetes mellitus. Subcutaneous arteries were isolated from tissues of healthy controls and diabetics. Vascular function was determined using wire myography. Expressions of proteins were measured by Western blotting and immunostaining. Endothelium-dependent relaxations to acetylcholine were impaired in arteries from diabetics compared to controls (P = 0.009). Acetylcholine-induced nitric oxide (NO)-mediated relaxations [in the presence of an inhibitor of cyclooxygenases (COX; indomethacin) and small and intermediate conductance calcium-activated potassium channel blockers (UCL1684 and TRAM 34, respectively)] were attenuated in arteries from diabetics compared to controls (P bioavailability; however, EDH appears to compensate, at least in part, for this dysfunction. PMID:26768833

  8. NATO-3C/Delta launch

    Science.gov (United States)

    1978-01-01

    NATO-3C, the third in a series of NATO defense-related communication satellites, is scheduled to be launched on a delta vehicle from the Eastern Test Range no earlier than November 15, 1978. NATO-3A and -3B were successfully launched by Delta vehicles in April 1976 and January 1977, respectively. The NATO-3C spacecraft will be capable of transmitting voice, data, facsimile, and telex messages among military ground stations. The launch vehicle for the NATO-3C mission will be the Delta 2914 configuration. The launch vehicle is to place the spacecraft in a synchronous transfer orbit. The spacecraft Apogee Kick motor is to be fired at fifth transfer orbit apogee to circularize its orbit at geosynchronous altitude of 35,900 km(22,260 miles) above the equator over the Atlantic Ocean somewhere between 45 and 50 degrees W longitude.

  9. Colloidally Synthesized Monodisperse Rh Nanoparticles Supported on SBA-15 for Size- and Pretreatment-Dependent Studies of CO Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Michael E.; Joo, Sang Hoon; Somorjai, Gabor A.

    2009-02-12

    A particle size dependence for CO oxidation over rhodium nanoparticles of 1.9-11.3 nm has been investigated and determined to be modified by the existence of the capping agent poly(vinylpyrrolidone) (PVP). The particles were prepared using a polyol reduction procedure with PVP as the capping agent. The Rh nanoparticles were subsequently supported on SBA-15 during hydrothermal synthesis to produce Rh/SBA-15 supported catalysts for size-dependent catalytic studies. CO oxidation by O{sub 2} at 40 Torr CO and 100 Torr O{sub 2} was investigated over two series of Rh/SBA-15 catalysts: as-synthesized Rh/SBA-15 covering the full range of Rh sizes and the same set of catalysts after high temperature calcination and reduction. The turnover frequency at 443 K increases from 0.4 to 1.7 s{sup -1} as the particle size decreases from 11.3 to 1.9 nm for the as-synthesized catalysts. After calcination and reduction, the turnover frequency is between 0.1 and 0.4 s{sup -1} with no particle size dependence. The apparent activation energy for all catalysts is {approx}30 kcal mol{sup -1} and is independent of particle size and thermal treatment. Infrared spectroscopy of CO on the Rh nanoparticles indicates that the heat treatments used influence the mode of CO adsorption. As a result, the particle size dependence for CO oxidation is altered after calcination and reduction of the catalysts. CO adsorbs at two distinct bridge sites on as-synthesized Rh/SBA-15, attributable to metallic Rh(0) and oxidized Rh(I) bridge sites. After calcination and reduction, however, CO adsorbs only at Rh(0) atop sites. The change in adsorption geometry and oxidation activity may be attributable to the interaction between PVP and the Rh surface. This capping agent affect may open new possibilities for the tailoring of metal catalysts using solution nanoparticle synthesis methods.

  10. The pathways of glutamate and glutamine oxidation by tumor cell mitochondria. Role of mitochondrial NAD(P)+-dependent malic enzyme.

    Science.gov (United States)

    Moreadith, R W; Lehninger, A L

    1984-05-25

    Little evidence has been available on the oxidative pathways of glutamine and glutamate, the major respiratory substrates of cancer cells. Glutamate formed from glutamine by phosphate-dependent glutaminase undergoes quantitative transamination by aerobic tumor mitochondria to yield aspartate. However, when malate is also added there is a pronounced decrease in aspartate production and a large formation of citrate and alanine, in both state 3 and 4 conditions. In contrast, addition of malate to normal rat heart, liver, or kidney mitochondria oxidizing glutamate causes a marked increase in aspartate production. Further analysis showed that extramitochondrial malate is oxidized almost quantitatively to pyruvate + CO2 by NAD(P)+-linked malic enzyme, present in the mitochondria of all tumors tested, but absent in heart, liver, and kidney mitochondria. On the other hand intramitochondrial malate generated from glutamate is oxidized quantitatively to oxalacetate by mitochondrial malate dehydrogenase of tumors. Acetyl-CoA derived from extramitochondrial malate via pyruvate and oxalacetate derived from glutamate via intramitochondrial malate are quantitatively converted into citrate, which is extruded. No evidence was found that malic enzyme of tumor mitochondria converts glutamate-derived malate into pyruvate as postulated in other reports. Possible mechanisms for the integration of mitochondrial malic enzyme and malate dehydrogenase activities in tumors are discussed. PMID:6144677

  11. α-Terpineol attenuates morphine-induced physical dependence and tolerance in mice: role of nitric oxide

    Science.gov (United States)

    Parvardeh, Siavash; Moghimi, Mahsa; Eslami, Pegah; Masoudi, Alireza

    2016-01-01

    Objective(s): Dependence and tolerance to opioid analgesics are major problems limiting their clinical application. α-Terpineol is a monoterpenoid alcohol with neuroprotective effects which is found in several medicinal plants such as Myrtus communis, Laurus nobilis, and Stachys byzantina. It has been shown that some of these medicinal plants such as S. byzantina attenuate dependence and tolerance to morphine. Since α-terpineol is one of the bioactive phytochemical constituent of these medicinal plants, the present study was conducted to investigate the effects of α-terpineol on morphine-induced dependence and tolerance in mice. Materials and Methods: The mice were rendered dependent or tolerant to morphine by a 3-day administration schedule. The hot-plate test and naloxone-induced withdrawal syndrome were used to evaluate tolerance and dependence on morphine, respectively. To investigate a possible role for nitric oxide (NO) in the protective effect of α-terpineol, the NO synthase inhibitor, L-N(G)-nitroarginine methyl ester (L-NAME) and NO precursor, L-arginine, were used. Results: Administration of α-terpineol (5, 10, and 20 mg/kg, IP) significantly decreased the number of jumps in morphine dependent animals. Moreover, α-terpineol (20 and 40 mg/kg, IP) attenuated tolerance to the analgesic effect of morphine. The inhibitory effects of α-terpineol on morphine-induced dependence and tolerance were enhanced by pretreatment with L-NAME (10 mg/kg, IP). However, L-arginine (300 mg/kg, IP) antagonized the protective effects of α-terpineol on dependence and tolerance to morphine. Conclusion: These findings indicate that α-terpineol prevents the development of dependence and tolerance to morphine probably through the influence on NO production. PMID:27081466

  12. Nitric oxide donors prevent while the nitric oxide synthase inhibitor L-NAME increases arachidonic acid plus CYP2E1-dependent toxicity

    International Nuclear Information System (INIS)

    toxicity. These results indicate that NO can be hepatoprotective against CYP2E1-dependent toxicity, preventing AA-induced oxidative stress

  13. Gastroprotective Effect of Geopropolis from Melipona scutellaris Is Dependent on Production of Nitric Oxide and Prostaglandin

    Directory of Open Access Journals (Sweden)

    Jerônimo Aparecido Ribeiro-Junior

    2015-01-01

    Full Text Available The aim of this study was to evaluate the gastroprotective activity of ethanolic extract of geopropolis (EEGP from Melipona scutellaris and to investigate the possible mechanisms of action. The gastroprotective activity of the EEGP was evaluated using model ulcer induced by ethanol. To elucidate the possible mechanisms of action, we investigated the involvement of the nonprotein sulfhydryl (NP-SH groups, nitric oxide and prostaglandins. In addition, the antisecretory activity of EEGP was also evaluated by pylorus ligated model. The EEGP orally administrated (300 mg/kg reduced the ulcerative lesions induced by the ethanol (P0.05. These results support the alternative medicine use of geopropolis as gastroprotective and the activities observed show to be related to nitric oxide and prostaglandins production.

  14. Gastroprotective Effect of Geopropolis from Melipona scutellaris Is Dependent on Production of Nitric Oxide and Prostaglandin.

    Science.gov (United States)

    Ribeiro-Junior, Jerônimo Aparecido; Franchin, Marcelo; Cavallini, Miriam Elias; Denny, Carina; de Alencar, Severino Matias; Ikegaki, Masaharu; Rosalen, Pedro Luiz

    2015-01-01

    The aim of this study was to evaluate the gastroprotective activity of ethanolic extract of geopropolis (EEGP) from Melipona scutellaris and to investigate the possible mechanisms of action. The gastroprotective activity of the EEGP was evaluated using model ulcer induced by ethanol. To elucidate the possible mechanisms of action, we investigated the involvement of the nonprotein sulfhydryl (NP-SH) groups, nitric oxide and prostaglandins. In addition, the antisecretory activity of EEGP was also evaluated by pylorus ligated model. The EEGP orally administrated (300 mg/kg) reduced the ulcerative lesions induced by the ethanol (P 0.05). These results support the alternative medicine use of geopropolis as gastroprotective and the activities observed show to be related to nitric oxide and prostaglandins production. PMID:25949263

  15. Thickness-dependent photocatalytic performance of graphite oxide for degrading organic pollutants under visible light.

    Science.gov (United States)

    Oh, Junghoon; Chang, Yun Hee; Kim, Yong-Hyun; Park, Sungjin

    2016-04-20

    Photocatalysts use sustainable solar light energy to trigger various catalytic reactions. Metal-free nanomaterials have been suggested as cost-effective and environmentally friendly photocatalysts. In this work, we propose thickness-controlled graphite oxide (GO) as a metal-free photocatalyst, which is produced by exfoliating thick GO particles via stirring and sonication. All GO samples exhibit photocatalytic activity for degrading an organic pollutant, rhodamine B under visible light, and the thickest sample shows the best catalytic performance. UV-vis-NIR diffuse reflectance absorption spectra indicate that thicker GO samples absorb more vis-NIR light than thinner ones. Density-functional theory calculations show that GO has a much smaller band gap than that of single-layer graphene oxide, and thus suggest that the largely-reduced band gap is responsible for this trend of light absorption. PMID:27040040

  16. Glycolytic Dependency of High-Level Nitric Oxide Resistance and Virulence in Staphylococcus aureus

    OpenAIRE

    Vitko, Nicholas P.; Spahich, Nicole A.; Richardson, Anthony R.

    2015-01-01

    ABSTRACT Staphylococcus aureus is a prolific human pathogen capable of causing severe invasive disease with a myriad of presentations. The ability of S. aureus to cause infection is strongly linked with its capacity to overcome the effects of innate immunity, whether by directly killing immune cells or expressing factors that diminish the impact of immune effectors. One such scenario is the induction of lactic acid fermentation by S. aureus in response to host nitric oxide (NO·). This ferment...

  17. Neurotoxicity of glia activated by gram-positive bacterial products depends on nitric oxide production.

    OpenAIRE

    Kim, Y. S.; Täuber, M G

    1996-01-01

    The present study examined the mechanism by which bacterial cell walls from two gram-positive meningeal pathogens, Streptococcus pneumoniae and the group B streptococcus, induced neuronal injury in primary cultures of rat brain cells. Cell walls from both organisms produced cellular injury to similar degrees in pure astrocyte cultures but not in pure neuronal cultures. Cell walls also induced nitric oxide production in cultures of astrocytes or microglia. When neurons were cultured together w...

  18. Size-dependant heating rates of iron oxide nanoparticles for magnetic fluid hyperthermia

    OpenAIRE

    Gonzales-Weimuller, Marcela; Zeisberger, Matthias; Krishnan, Kannan M

    2009-01-01

    Using the thermal decomposition of organometallics method we have synthesized high-quality, iron oxide nanoparticles of tailorable size up to ~15nm and transferred them to a water phase by coating with a biocompatible polymer. The magnetic behavior of these particles was measured and fit to a log-normal distribution using the Chantrell method and their polydispersity was confirmed to be very narrow. By performing calorimetry measurements with these monodisperse particles we have unambiguously...

  19. The oxidative costs of reproduction are group-size dependent in a wild cooperative breeder

    OpenAIRE

    Dominic L Cram; Blount, Jonathan D.; Young, Andrew J.

    2015-01-01

    Life-history theory assumes that reproduction entails a cost, and research on cooperatively breeding societies suggests that the cooperative sharing of workloads can reduce this cost. However, the physiological mechanisms that underpin both the costs of reproduction and the benefits of cooperation remain poorly understood. It has been hypothesized that reproductive costs may arise in part from oxidative stress, as reproductive investment may elevate exposure to reactive oxygen species, compro...

  20. Gastroprotective Effect of Geopropolis from Melipona scutellaris Is Dependent on Production of Nitric Oxide and Prostaglandin

    OpenAIRE

    Jerônimo Aparecido Ribeiro-Junior; Marcelo Franchin; Miriam Elias Cavallini; Carina Denny; Severino Matias de Alencar; Masaharu Ikegaki; Pedro Luiz Rosalen

    2015-01-01

    The aim of this study was to evaluate the gastroprotective activity of ethanolic extract of geopropolis (EEGP) from Melipona scutellaris and to investigate the possible mechanisms of action. The gastroprotective activity of the EEGP was evaluated using model ulcer induced by ethanol. To elucidate the possible mechanisms of action, we investigated the involvement of the nonprotein sulfhydryl (NP-SH) groups, nitric oxide and prostaglandins. In addition, the antisecretory activity of EEGP was al...

  1. Chlorine Gas Exposure Causes Systemic Endothelial Dysfunction by Inhibiting Endothelial Nitric Oxide Synthase–Dependent Signaling

    OpenAIRE

    Honavar, Jaideep; Samal, Andrey A.; Bradley, Kelley M.; Brandon, Angela; Balanay, Joann; Squadrito, Giuseppe L.; MohanKumar, Krishnan; Maheshwari, Akhil; Postlethwait, Edward M.; Matalon, Sadis; Patel, Rakesh P.

    2010-01-01

    Chlorine gas (Cl2) exposure during accidents or in the military setting results primarily in injury to the lungs. However, the potential for Cl2 exposure to promote injury to the systemic vasculature leading to compromised vascular function has not been studied. We hypothesized that Cl2 promotes extrapulmonary endothelial dysfunction characterized by a loss of endothelial nitric oxide synthase (eNOS)-derived signaling. Male Sprague Dawley rats were exposed to Cl2 for 30 minutes, and eNOS-depe...

  2. Versatile Redox Chemistry Complicates Antioxidant Capacity Assessment: Flavonoids as Milieu-Dependent Antiand Pro-Oxidants

    OpenAIRE

    Gert Bachmann; Lenka Kubicova; Vladimir Chobot; Franz Hadacek

    2013-01-01

    Some antioxidants have been shown to possess additional pro-oxidant effects. Diverse methodologies exist for studying redox properties of synthetic and natural chemicals. The latter are substantial components of our diet. Exploration of their contribution to life-extending or -compromising effects is mandatory. Among reactive oxygen species (ROS), hydroxyl radical (•OH) is the most damaging species. Due to its short half-life, the assay has to contain a specific generation system. Plants synt...

  3. Graphene oxide-dependent growth and self-aggregation into a hydrogel complex of exoelectrogenic bacteria

    OpenAIRE

    Naoko Yoshida; Yasushi Miyata; Kasumi Doi; Yuko Goto; Yuji Nagao; Ryugo Tero; Akira Hiraishi

    2016-01-01

    Graphene oxide (GO) is reduced by certain exoelectrogenic bacteria, but its effects on bacterial growth and metabolism are a controversial issue. This study aimed to determine whether GO functions as the terminal electron acceptor to allow specific growth of and electricity production by exoelectrogenic bacteria. Cultivation of environmental samples with GO and acetate as the sole substrate could specifically enrich exoelectrogenic bacteria with Geobacter species predominating (51–68% of the ...

  4. Dose dependent effects of inhaled ethylene oxide on spermatogenesis in rats.

    OpenAIRE

    Mori, K; Kaido, M.; Fujishiro, K.; Inoue, N.; Koide, O; Hori, H; Tanaka, I

    1991-01-01

    Male Wistar rats were exposed to ethylene oxide (EO) at concentrations of 50, 100, or 250 ppm for six hours a day, on five days a week for 13 weeks. Dose effect relations of inhaled EO on spermatogenesis were evaluated from testicular and epididymal weights, histopathological changes and lactate dehydrogenase X (LDH X) activity in the testis, and sperm counts and sperm head abnormalities in the epididymis. At 250 ppm, a decrease in epididymal weights, slight degenerations in the seminiferous ...

  5. Carbon and hydrogen isotope fractionation during nitrite-dependent anaerobic methane oxidation by Methylomirabilis oxyfera

    Science.gov (United States)

    Rasigraf, Olivia; Vogt, Carsten; Richnow, Hans-Hermann; Jetten, Mike S. M.; Ettwig, Katharina F.

    2012-07-01

    Anaerobic oxidation of methane coupled to nitrite reduction is a recently discovered methane sink of as yet unknown global significance. The bacteria that have been identified to carry out this process, Candidatus Methylomirabilis oxyfera, oxidize methane via the known aerobic pathway involving the monooxygenase reaction. In contrast to aerobic methanotrophs, oxygen is produced intracellularly and used for the activation of methane by a phylogenetically distinct particulate methane monooxygenase (pMMO). Here we report the fractionation factors for carbon and hydrogen during methane oxidation by an enrichment culture of M. oxyfera bacteria. In two separate batch incubation experiments with different absolute biomass and methane contents, the specific methanotrophic activity was similar and the progressive isotope enrichment identical. Headspace methane was consumed up to 98% with rates showing typical first order reaction kinetics. The enrichment factors determined by Rayleigh equations were -29.2 ± 2.6‰ for δ13C (εC) and -227.6 ± 13.5‰ for δ2H (εH), respectively. These enrichment factors were in the upper range of values reported so far for aerobic methanotrophs. In addition, two-dimensional specific isotope analysis (Λ = ( α H - 1 - 1)/( α C - 1 - 1)) was performed and also the determined Λ value of 9.8 was within the range determined for other aerobic and anaerobic methanotrophs. The results showed that in contrast to abiotic processes biological methane oxidation exhibits a narrow range of fractionation factors for carbon and hydrogen irrespective of the underlying biochemical mechanisms. This work will therefore facilitate the correct interpretation of isotopic composition of atmospheric methane with implications for modeling of global carbon fluxes.

  6. Fe biomineralization mirrors individual metabolic activity in a nitrate-dependent Fe(II)-oxidizer

    OpenAIRE

    Miot, Jennyfer; Remusat, Laurent; Duprat, Elodie; Gonzalez, Adriana; Pont, Sylvain; Poinsot, Mélanie

    2015-01-01

    Microbial biomineralization sometimes leads to periplasmic encrustation, which is predicted to enhance microorganism preservation in the fossil record. Mineral precipitation within the periplasm is, however, thought to induce death, as a result of permeability loss preventing nutrient and waste transit across the cell wall. This hypothesis had, however, never been investigated down to the single cell level. Here, we cultured the nitrate reducing Fe(II) oxidizing bacteria Acidovorax sp. strain...

  7. Progressive handgrip exercise: evidence of nitric oxide-dependent vasodilation and blood flow regulation in humans

    OpenAIRE

    Wray, D. Walter; Witman, Melissa A. H.; Ives, Stephen J.; McDaniel, John; Fjeldstad, Anette S.; Trinity, Joel D.; Conklin, Jamie D.; Supiano, Mark A.; Richardson, Russell S.

    2011-01-01

    In the peripheral circulation, nitric oxide (NO) is released in response to shear stress across vascular endothelial cells. We sought to assess the degree to which NO contributes to exercise-induced vasodilation in the brachial artery (BA) and to determine the potential of this approach to noninvasively evaluate NO bioavailability. In eight young (25 ± 1 yr) healthy volunteers, we used ultrasound Doppler to examine BA vasodilation in response to handgrip exercise (4, 8, 12, 16, 20, and 24 kg)...

  8. Peroxidase-dependent apoplastic oxidative burst in Arabidopsis required for pathogen resistance.

    Science.gov (United States)

    Bindschedler, Laurence V; Dewdney, Julia; Blee, Kris A; Stone, Julie M; Asai, Tsuneaki; Plotnikov, Julia; Denoux, Carine; Hayes, Tezni; Gerrish, Chris; Davies, Dewi R; Ausubel, Frederick M; Bolwell, G Paul

    2006-09-01

    The oxidative burst is an early response to pathogen attack leading to the production of reactive oxygen species (ROS) including hydrogen peroxide. Two major mechanisms involving either NADPH oxidases or peroxidases that may exist singly or in combination in different plant species have been proposed for the generation of ROS. We identified an Arabidopsis thaliana azide-sensitive but diphenylene iodonium-insensitive apoplastic oxidative burst that generates H(2)O(2) in response to a Fusarium oxysporum cell-wall preparation. Transgenic Arabidopsis plants expressing an anti-sense cDNA encoding a type III peroxidase, French bean peroxidase type 1 (FBP1) exhibited an impaired oxidative burst and were more susceptible than wild-type plants to both fungal and bacterial pathogens. Transcriptional profiling and RT-PCR analysis showed that the anti-sense (FBP1) transgenic plants had reduced levels of specific peroxidase-encoding mRNAs, including mRNAs corresponding to Arabidopsis genes At3g49120 (AtPCb) and At3g49110 (AtPCa) that encode two class III peroxidases with a high degree of homology to FBP1. These data indicate that peroxidases play a significant role in generating H(2)O(2) during the Arabidopsis defense response and in conferring resistance to a wide range of pathogens. PMID:16889645

  9. Impact of electric-field dependent dielectric constants on two-dimensional electron gases in complex oxides

    International Nuclear Information System (INIS)

    High-density two-dimensional electron gas (2DEG) can be formed at complex oxide interfaces such as SrTiO3/GdTiO3 and SrTiO3/LaAlO3. The electric field in the vicinity of the interface depends on the dielectric properties of the material as well as on the electron distribution. However, it is known that electric fields can strongly modify the dielectric constant of SrTiO3 as well as other complex oxides. Solving the electrostatic problem thus requires a self-consistent approach in which the dielectric constant varies according to the local magnitude of the field. We have implemented the field dependence of the dielectric constant in a Schrödinger-Poisson solver in order to study its effect on the electron distribution in a 2DEG. Using the SrTiO3/GdTiO3 interface as an example, we demonstrate that including the field dependence results in the 2DEG being confined closer to the interface compared to assuming a single field-independent value for the dielectric constant. Our conclusions also apply to SrTiO3/LaAlO3 as well as other similar interfaces

  10. The Traditional Herbal Medicine, Dangkwisoo-San, Prevents Cerebral Ischemic Injury through Nitric Oxide-Dependent Mechanisms

    Directory of Open Access Journals (Sweden)

    Ji Hyun Kim

    2011-01-01

    Full Text Available Dangkwisoo-San (DS is an herbal extract that is widely used in traditional Korean medicine to treat traumatic ecchymosis and pain by promoting blood circulation and relieving blood stasis. However, the effect of DS in cerebrovascular disease has not been examined experimentally. The protective effects of DS on focal ischemic brain were investigated in a mouse model. DS stimulated nitric oxide (NO production in human brain microvascular endothelial cells (HBMECs. DS (10–300 μg/mL produced a concentration-dependent relaxation in mouse aorta, which was significantly attenuated by the nitric oxide synthase (NOS inhibitor L-NAME, suggesting that DS causes vasodilation via a NO-dependent mechanism. DS increased resting cerebral blood flow (CBF, although it caused mild hypotension. To investigate the effect of DS on the acute cerebral injury, C57/BL6J mice received 90 min of middle cerebral artery occlusion followed by 22.5 h of reperfusion. DS administered 3 days before arterial occlusion significantly reduced cerebral infarct size by 53.7% compared with vehicle treatment. However, DS did not reduce brain infarction in mice treated with the relatively specific endothelial NOS (eNOS inhibitor, N5-(1-iminoethyl-L-ornithine, suggesting that the neuroprotective effect of DS is primarily endothelium-dependent. This correlated with increased phosphorylation of eNOS in the brains of DS-treated mice. DS acutely improves CBF in eNOS-dependent vasodilation and reduces infarct size in focal cerebral ischemia. These data provide causal evidence that DS is cerebroprotective via the eNOS-dependent production of NO, which ameliorates blood circulation.

  11. Unravelling the dependence of hydrogen oxidation kinetics on the size of Pt nanoparticles by in operando nanoplasmonic temperature sensing.

    Science.gov (United States)

    Wettergren, Kristina; Hellman, Anders; Cavalca, Filippo; Zhdanov, Vladimir P; Langhammer, Christoph

    2015-01-14

    We use a noninvasive nanoscale optical-temperature measurement method based on localized surface plasmon resonance to investigate the particle size-dependence of the hydrogen oxidation reaction kinetics on model supported Pt nanocatalysts at atmospheric pressure in operando. With decreasing average nanoparticle size from 11 down to 3 nm, the apparent reaction activation energy is found to increase from 0.5 up to 0.8 eV. This effect is attributed to an increase of the fraction of (100)-facet and edge and corner sites and their increasingly important role in the reaction with decreasing particle size. PMID:25479190

  12. Liver Oxidative Stress after Renal Ischemia-Reperfusion Injury is Leukocyte Dependent in Inbred Mice

    OpenAIRE

    Khastar, Hossein; Kadkhodaee, Mehri; Sadeghipour, Hamid Reza; Seifi, Behjat; Hadjati, Jamshid; Najafi, Atefeh; Soleimani, Manoocher

    2011-01-01

    Objective(s) There are some reports in recent years indicating that renal ischemia – reperfusion (IR) induces deleterious changes in remote organs such as liver. The aim of this study was to investigate whether leukocytes have a role on the induction of oxidative stress in liver after renal IR. Materials and Methods Inbred mice in IR donor group were subjected to renal IR injury. In sham donor group the procedure was almost the same except that ischemia was not induced. Then, mice were anesth...

  13. Akt-dependent phosphorylation of endothelial nitric-oxide synthase mediates penile erection

    OpenAIRE

    Hurt, K. Joseph; Musicki, Biljana; Palese, Michael A.; Crone, Julie K.; Becker, Robyn E.; Moriarity, John L.; Snyder, Solomon H.; Burnett, Arthur L.

    2002-01-01

    In the penis, nitric oxide (NO) can be formed by both neuronal NO synthase and endothelial NOS (eNOS). eNOS is activated by viscous drag/shear stress in blood vessels to produce NO continuously, a process mediated by the phosphatidylinositol 3-kinase (PI3kinase)/Akt pathway. Here we show that PI3-kinase/Akt physiologically mediates erection. Both electrical stimulation of the cavernous nerve and direct intracavernosal injection of the vasorelaxant drug papaverine cause rapid increases in phos...

  14. The senescence-accelerated mouse (SAM): a higher oxidative stress and age-dependent degenerative diseases model.

    Science.gov (United States)

    Chiba, Yoichi; Shimada, Atsuyoshi; Kumagai, Naoko; Yoshikawa, Keisuke; Ishii, Sanae; Furukawa, Ayako; Takei, Shiro; Sakura, Masaaki; Kawamura, Noriko; Hosokawa, Masanori

    2009-04-01

    The SAM strain of mice is actually a group of related inbred strains consisting of a series of SAMP (accelerated senescence-prone) and SAMR (accelerated senescence-resistant) strains. Compared with the SAMR strains, the SAMP strains show a more accelerated senescence process, a shorter lifespan, and an earlier onset and more rapid progress of age-associated pathological phenotypes similar to human geriatric disorders. The higher oxidative stress status observed in SAMP mice is partly caused by mitochondrial dysfunction, and may be a cause of this senescence acceleration and age-dependent alterations in cell structure and function. Based on our recent observations, we discuss a possible mechanism for mitochondrial dysfunction resulting in the excessive production of reactive oxygen species, and a role for the hyperoxidative stress status in neurodegeneration in SAMP mice. These SAM strains can serve as a useful tool to understand the cellular mechanisms of age-dependent degeneration, and to develop clinical interventions. PMID:18688709

  15. Localized LoxL3-Dependent Fibronectin Oxidation Regulates Myofiber Stretch and Integrin-Mediated Adhesion.

    Science.gov (United States)

    Kraft-Sheleg, Ortal; Zaffryar-Eilot, Shelly; Genin, Olga; Yaseen, Wesal; Soueid-Baumgarten, Sharon; Kessler, Ofra; Smolkin, Tatyana; Akiri, Gal; Neufeld, Gera; Cinnamon, Yuval; Hasson, Peleg

    2016-03-01

    For muscles to function, myofibers have to stretch and anchor at the myotendinous junction (MTJ), a region rich in extracellular matrix (ECM). Integrin signaling is required for MTJ formation, and mutations affecting the cascade lead to muscular dystrophies in mice and humans. Underlying mechanisms for integrin activation at the MTJ and ECM modifications regulating its signaling are unclear. We show that lysyl oxidase-like 3 (LoxL3) is a key regulator of integrin signaling that ensures localized control of the cascade. In LoxL3 mutants, myofibers anchor prematurely or overshoot to adjacent somites, and are loose and lack tension. We find that LoxL3 complexes with and directly oxidizes Fibronectin (FN), an ECM scaffold protein and integrin ligand enriched at the MTJ. We identify a mechanism whereby localized LoxL3 secretion from myofiber termini oxidizes FN, enabling enhanced integrin activation at the tips of myofibers and ensuring correct positioning and anchoring of myofibers along the MTJ. PMID:26954549

  16. Metal oxide/polyaniline nanocomposites: Cluster size and composition dependent structural and magnetic properties

    Indian Academy of Sciences (India)

    Raksha Sharma; Rakesh Malik; Subhalakshmi Lamba; S Annapoorni

    2008-06-01

    Nanocomposites of iron oxide with conducting polymer in the form of powders of varying compositions have been studied to understand the effects of particle size, cluster size and magnetic inter-particle interactions. The sizes of the nanoparticles were estimated to be ∼ 10–20 nm from the X-ray diffraction (XRD) and the transmission electron micrographs (TEM). XRD shows a single crystalline phase for the -Fe2O3. The presence of conducting polymer was confirmed through Fourier transform infrared (FTIR) spectroscopy. The amount of polymer present in the composite, the transition temperature of iron oxide and the thermal stability of polymer was determined through thermogravimetric and differential thermal analysis (TGA–DTA). The room temperature magnetic hysteresis measurements show reduction in saturation magnetization with increasing polymer concentrations. A low value of coercivity was observed for low polymer composites. On increasing the polymer concentration, the coercivity and remanence become negligible indicating a superparamagnetic phase at room temperature. Beyond a certain composition, the system shows paramagnetic behaviour which is also confirmed through zero field cooled–field cooled (ZFC–FC) measurements. We also report preliminary results on the magnetic properties of self standing sheets prepared using -Fe2O3 and NiFe2O4 nanoparticles and conducting polymers.

  17. Strain-dependent oxidant release in articular cartilage originates from mitochondria.

    Science.gov (United States)

    Brouillette, M J; Ramakrishnan, P S; Wagner, V M; Sauter, E E; Journot, B J; McKinley, T O; Martin, J A

    2014-06-01

    Mechanical loading is essential for articular cartilage homeostasis and plays a central role in the cartilage pathology, yet the mechanotransduction processes that underlie these effects remain unclear. Previously, we showed that lethal amounts of reactive oxygen species (ROS) were liberated from the mitochondria in response to mechanical insult and that chondrocyte deformation may be a source of ROS. To this end, we hypothesized that mechanically induced mitochondrial ROS is related to the magnitude of cartilage deformation. To test this, we measured axial tissue strains in cartilage explants subjected to semi-confined compressive stresses of 0, 0.05, 0.1, 0.25, 0.5, or 1.0 MPa. The presence of ROS was then determined by confocal imaging with dihydroethidium, an oxidant sensitive fluorescent probe. Our results indicated that ROS levels increased linearly relative to the magnitude of axial strains (r(2) = 0.87, p 40%. By contrast, hydrostatic stress, which causes minimal tissue strain, had no significant effect. Cell-permeable superoxide dismutase mimetic Mn(III)tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride significantly decreased ROS levels at 0.5 and 0.25 MPa. Electron transport chain inhibitor, rotenone, and cytoskeletal inhibitor, cytochalasin B, significantly decreased ROS levels at 0.25 MPa. Our findings strongly suggest that ROS and mitochondrial oxidants contribute to cartilage mechanobiology. PMID:23896937

  18. Nitric oxide synthase-dependent immune response against gram negative bacteria in a crustacean, Litopenaeus vannamei.

    Science.gov (United States)

    Rodríguez-Ramos, Tania; Carpio, Yamila; Bolívar, Jorge; Gómez, Leonardo; Estrada, Mario Pablo; Pendón, Carlos

    2016-03-01

    Nitric oxide (NO) is a short-lived radical generated by nitric oxide synthases (NOS). NO is involved in a variety of functions in invertebrates, including host defense. In previous studies, we isolated and sequenced for the first time the NOS gene from hemocytes of Panulirus argus, demonstrating the inducibility of this enzyme by lipopolysaccharide in vitro e in vivo. Hyperimmune serum was obtained from rabbits immunized with a P. argus -NOS fragment of 31 kDa produced in Escherichia coli, which specifically detected the recombinant polypeptide and the endogenous NOS from lobster hemocytes by western blotting and immunofluorescence. In the present work, we demonstrate that the hyperimmune serum obtained against P. argus NOS also recognizes Litopenaeus vannamei NOS in hemocytes by western blotting and immunofluorescence. Our data also show that while the hemolymph of L. vannamei has a strong antibacterial activity against the Gram negative bacteria Aeromonas hydrophila, the administration of the anti NOS serum reduce the natural bacterial clearance. These results strongly suggest that NOS is required for the shrimp immune defense toward Gram negative bacteria. Therefore, the monitoring of induction of NOS could be an important tool for testing immunity in shrimp farming. PMID:26804662

  19. Concentration-dependent photodegradation kinetics and hydroxyl-radical oxidation of phenicol antibiotics.

    Science.gov (United States)

    Li, Kai; Zhang, Peng; Ge, Linke; Ren, Honglei; Yu, Chunyan; Chen, Xiaoyang; Zhao, Yuanfeng

    2014-09-01

    Thiamphenicol and florfenicol are two phenicol antibiotics widely used in aquaculture and are ubiquitous as micropollutants in surface waters. The present study investigated their photodegradation kinetics, hydroxyl-radical (OH) oxidation reactivities and products. Firstly, the photolytic kinetics of the phenicols in pure water was studied as a function of initial concentrations (C0) under UV-vis irradiation (λ>200nm). It was found that the kinetics was influenced by C0. A linear plot of the pseudo-first-order rate constant vs C0 was observed with a negative slope. Secondly, the reaction between the phenicol antibiotics and OH was examined with a competition kinetic method under simulated solar irradiation (λ>290nm), which quantified their bimolecular reaction rate constants of (2.13±0.02)×10(9)M(-1)s(-1) and (1.82±0.10)×10(9)M(-1)s(-1) for thiamphenicol and florfenicol, respectively. Then the corresponding OH oxidated half-lives in sunlit surface waters were calculated to be 90.5-106.1h. Some main intermediates were formed from the reaction, which suggested that the two phenicols underwent hydroxylation, oxygenation and dehydrogenation when OH existed. These results are of importance to assess the phenicol persistence in wastewater treatment and sunlit surface waters. PMID:24997929

  20. Lung injury-dependent oxidative status and chymotrypsin-like activity of skeletal muscles in hamsters with experimental emphysema

    Directory of Open Access Journals (Sweden)

    Tonon Jair

    2013-01-01

    Full Text Available Abstract Background Peripheral skeletal muscle is altered in patients suffering from emphysema and chronic obstructive pulmonary disease (COPD. Oxidative stress have been demonstrated to participate on skeletal muscle loss of several states, including disuse atrophy, mechanical ventilation, and chronic diseases. No evidences have demonstrated the occurance in a severity manner. Methods We evaluated body weight, muscle loss, oxidative stress, and chymotrypsin-like proteolytic activity in the gastrocnemius muscle of emphysemic hamsters. The experimental animals had 2 different severities of lung damage from experimental emphysema induced by 20 mg/mL (E20 and 40 mg/mL (E40 papain. Results The severity of emphysema increased significantly in E20 (60.52 ± 2.8, p Conclusions Taken together, the results of the present study suggest that muscle atrophy observed in this model of emphysema is mediated by increased muscle chymotrypsin-like activity, with possible involvement of oxidative stress in a severity-dependent manner.

  1. In vitro Staphylococcus aureus-induced oxidative stress in mice murine peritoneal macrophages:a duration-dependent approach

    Institute of Scientific and Technical Information of China (English)

    Subhankari Prasad Chakraborty; Somenath Roy

    2014-01-01

    Objective: To evaluate the free radical generation and status of the antioxidant enzymes in murine peritoneal macrophage during in vitro vancomycin sensitive Staphylococcus aureus (VSSA) treatment with different time interval.Methods:Peritoneal macrophages were treated with 5í106 CFU/mL VSSA cell suspension in vitro for different time interval (1, 2, 3, 6, 12, and 24 h) and superoxide anion generation, NADPH oxidase activity, myeloperoxidase activity, nitric oxide generation, antioxidant enzyme status and components of glutathione cycle were analyzed.Results:Superoxide anion generation, NADPH oxidase activity, myeloperoxidase activity and nitric oxide generation got peak at 3 h, indicating maximum free radical generation through activation of NADPH oxidase in murine peritoneal macrophages during VSSA infection. Reduced glutathione level, glutathione peroxidase, glutathione reductase, and glutathione-s-transferase activity were decreased significantly (P<0.05) with increasing time of VSSA infection. But the oxidized glutathione level was time dependently increased significantly (P<0.05) in murine peritoneal macrophages. All the changes in peritoneal macrophages after 3 h in vitro VSSA treatment had no significant difference.Conclusions:From this study, it may be summarized that in vitro VSSA infection not only generates excess free radical but also affects the antioxidant status and glutathione cycle in murine peritoneal macrophages.

  2. The Structure-Dependent Electric Release and Enhanced Oxidation of Drug in Graphene Oxide-Based Nanocarrier Loaded with Anticancer Herbal Drug Berberine.

    Science.gov (United States)

    Yu, Danni; Ruan, Pan; Meng, Ziyuan; Zhou, Jianping

    2015-08-01

    The aim of the current investigation is to explore graphene oxide (GO) special electric and electrochemical properties in modulating and tuning drug delivery in tumor special environment of electrophysiology. The electric-sensitive drug release and redox behavior of GO-bearing berberine (Ber) was studied. Drug release in cell potential was applied in a designed electrode system: tumor environment was simulated at pH 6.2 with 0.1 V pulse voltage, whereas the normal was at pH 7.4 with 0.2 V. Quite different from the pH-depended profile, the electricity-triggered behavior indicated a high correlation with the carriers' structure: GO-based nanocomposite showed a burst release on its special "skin effect," whereas the PEGylated ones released slowly owing to the electroviscous effect of polymer. Cyclic voltammetry was used to investigate the redox behaviors of colloid PEGylated GO toward absorbed Ber in pH 5.8 and 7.2 solutions. After drug loading, the oxidation of Ber was enhanced in a neutral environment, whereas the enhancement of PEG-GO was in an acidic one, which means a possible increased susceptibility of their biotransformation in vivo. The studies designed in this work may help to establish a kind of carrier system for the sensitive delivery and metabolic regulation of drugs according to the different electrophysiological environment in tumor therapy. PMID:26052932

  3. Mistletoe (Viscum album) infestation in the Scots pine stimulates drought-dependent oxidative damage in summer.

    Science.gov (United States)

    Mutlu, Salih; Ilhan, Veli; Turkoglu, Halil Ibrahim

    2016-04-01

    This study sought to contribute to the understanding of the detrimental effect of the mistletoe (Viscum albumL.), a hemiparasitic plant, on the mortality of the Scots pine (Pinus sylvestrisL.). Fieldwork was conducted in the town of Kelkit (Gumushane province, Turkey) from April to October in 2013. Pine needles of similar ages were removed from the branches of mistletoe-infested and noninfested Scots pine plants, then transported to the laboratory and used as research materials. The effects of the mistletoe on the Scots pine during infestation were evaluated by determining the levels of water, electrolyte leakage (EL), malondialdehyde (MDA, being a product of lipid peroxidation) and reactive oxygen species (ROS) such as superoxide anion (O2 (-•)), hydrogen peroxide (H2O2) and hydroxyl radical ((•)OH). In addition, the activities of antioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were measured in the same samples. The highest level of drought stress was found in summer (especially in August) as a result of the lowest water content in the soil and the highest average temperature occurring in these months. The drought stress induced by mistletoe infestation caused a regular decrease in water content, while it increased the levels of EL, MDA and ROS (H2O2, O2 (-•)and(•)OH). The infestation also stimulated the activities of CAT and POX, with the exception of SOD. On the other hand, in August, when the drought conditions were the harshest, the levels of EL and MDA, which are two of the most important indicator parameters for oxidative stress, as well as the levels of H2O2and(•)OH, which are two of the ROS leading to oxidative stress, reached the highest values in both infested and noninfested needles, whereas the O2 (-•)level decreased. For the same period and needles, CAT activity increased, while SOD activity decreased. Peroxidase activity, however, did not exhibit a significant change. Our findings indicate

  4. Redox signaling via oxidative inactivation of PTEN modulates pressure-dependent myogenic tone in rat middle cerebral arteries.

    Directory of Open Access Journals (Sweden)

    Debebe Gebremedhin

    Full Text Available The present study examined the level of generation of reactive oxygen species (ROS and roles of inactivation of the phosphatase PTEN and the PI3K/Akt signaling pathway in response to an increase in intramural pressure-induced myogenic cerebral arterial constriction. Step increases in intraluminal pressure of cannulated cerebral arteries induced myogenic constriction and concomitant formation of superoxide (O2 (.- and its dismutation product hydrogen peroxide (H2O2 as determined by fluorescent HPLC analysis, microscopic analysis of intensity of dihydroethidium fluorescence and attenuation of pressure-induced myogenic constriction by pretreatment with the ROS scavenger 4,hydroxyl-2,2,6,6-tetramethylpiperidine1-oxyl (tempol or Mito-tempol or MitoQ in the presence or absence of PEG-catalase. An increase in intraluminal pressure induced oxidation of PTEN and activation of Akt. Pharmacological inhibition of endogenous PTEN activity potentiated pressure-dependent myogenic constriction and caused a reduction in NPo of a 238 pS arterial KCa channel current and an increase in [Ca(2+]i level in freshly isolated cerebral arterial muscle cells (CAMCs, responses that were attenuated by Inhibition of the PI3K/Akt pathway. These findings demonstrate an increase in intraluminal pressure induced increase in ROS production triggered redox-sensitive signaling mechanism emanating from the cross-talk between oxidative inactivation of PTEN and activation of the PI3K/Akt signaling pathway that involves in the regulation of pressure-dependent myogenic cerebral arterial constriction.

  5. Salinity-dependent nickel accumulation and effects on respiration, ion regulation and oxidative stress in the galaxiid fish, Galaxias maculatus.

    Science.gov (United States)

    Blewett, Tamzin A; Wood, Chris M; Glover, Chris N

    2016-07-01

    Inanga (Galaxias maculatus) are a euryhaline and amphidromous Southern hemisphere fish species inhabiting waters highly contaminated in trace elements such as nickel (Ni). Ni is known to exert its toxic effects on aquatic biota via three key mechanisms: inhibition of respiration, impaired ion regulation, and stimulation of oxidative stress. Inanga acclimated to freshwater (FW), 50% seawater (SW) or 100% SW were exposed to 0, 150 or 2000 μg Ni L(-1), and tissue Ni accumulation, metabolic rate, ion regulation (tissue ions, calcium (Ca) ion influx), and oxidative stress (catalase activity, protein carbonylation) were measured after 96 h. Ni accumulation increased with Ni exposure concentration in gill, gut and remaining body, but not in liver. Only in the gill was Ni accumulation affected by exposure salinity, with lower branchial Ni burdens in 100% and 50% SW inanga, relative to FW fish. There were no Ni-dependent effects on respiration, or Ca influx, and the only Ni-dependent effect on tissue ion content was on gill potassium. Catalase activity and protein carbonylation were affected by Ni, primarily in FW, but only at 150 μg Ni L(-1). Salinity therefore offsets the effects of Ni, despite minimal changes in Ni bioavailability. These data suggest only minor effects of Ni in inanga, even at highly elevated environmental Ni concentrations. PMID:27077552

  6. Lipotoxic brain microvascular injury is mediated by activating transcription factor 3-dependent inflammatory and oxidative stress pathways.

    Science.gov (United States)

    Aung, Hnin Hnin; Altman, Robin; Nyunt, Tun; Kim, Jeffrey; Nuthikattu, Saivageethi; Budamagunta, Madhu; Voss, John C; Wilson, Dennis; Rutledge, John C; Villablanca, Amparo C

    2016-06-01

    Dysfunction of the cerebrovasculature plays an important role in vascular cognitive impairment (VCI). Lipotoxic injury of the systemic endothelium in response to hydrolyzed triglyceride-rich lipoproteins (TGRLs; TGRL lipolysis products) or a high-fat Western diet (WD) suggests similar mechanisms may be present in brain microvascular endothelium. We investigated the hypothesis that TGRL lipolysis products cause lipotoxic injury to brain microvascular endothelium by generating increased mitochondrial superoxide radical generation, upregulation of activating transcription factor 3 (ATF3)-dependent inflammatory pathways, and activation of cellular oxidative stress and apoptotic pathways. Human brain microvascular endothelial cells were treated with human TGRL lipolysis products that induced intracellular lipid droplet formation, mitochondrial superoxide generation, ATF3-dependent transcription of proinflammatory, stress response, and oxidative stress genes, as well as activation of proapoptotic cascades. Male apoE knockout mice were fed a high-fat/high-cholesterol WD for 2 months, and brain microvessels were isolated by laser capture microdissection. ATF3 gene transcription was elevated 8-fold in the hippocampus and cerebellar brain region of the WD-fed animals compared with chow-fed control animals. The microvascular injury phenotypes observed in vitro and in vivo were similar. ATF3 plays an important role in mediating brain microvascular responses to acute and chronic lipotoxic injury and may be an important preventative and therapeutic target for endothelial dysfunction in VCI. PMID:27087439

  7. Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

    KAUST Repository

    Abutaha, Anas I.

    2013-02-06

    We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature of the laser deposition process on LaAlO3 (100) substrates. The change in surface termination of the LaAlO3 substrate with temperature induces a change in AZO film orientation. The anisotropic nature of electrical conductivity and Seebeck coefficient of the AZO films showed a favored thermoelectric performance in c-axis oriented films. These films gave the highest power factor of 0.26 W m−1 K−1 at 740 K.

  8. Oxidation of intramyocellular lipids is dependent on mitochondrial function and the availability of extracellular fatty acids

    DEFF Research Database (Denmark)

    Corpeleijn, Eva; Hessvik, Nina P; Bakke, Siril S;

    2010-01-01

    were extended by comparing these processes in primary cultured myotubes established from healthy lean and obese type 2 diabetic (T2D) individuals, two extremes in a range of metabolic phenotypes. ICLs were prelabeled for 2 days with 100 microM [(14)C]oleic acid (OA). ICL(OX) was studied using a (14)CO......Obesity and insulin resistance are related to both enlarged intramyocellular triacylglycerol stores and accumulation of lipid intermediates. We investigated how lipid overflow can change the oxidation of intramyocellular lipids (ICL(OX)) and intramyocellular lipid storage (ICL). These experiments...... all, a lower mitochondrial mass and lower ICL(OX) were related to a higher cell-associated OA accumulation. Second, myotubes established from obese T2D individuals showed reduced ICL(OX). ICL(OX) remained lower during uncoupling (P <0.001), even with comparable mitochondrial mass, suggesting decreased...

  9. Orientation-dependent recrystallization in an oxide dispersion strengthened steel after dynamic plastic deformation

    DEFF Research Database (Denmark)

    Zhang, Zhenbo; Tao, N.R.; Mishin, Oleg V.;

    2015-01-01

    recrystallization are found in the 〈111〉- oriented lamellae, which had a higher stored energy density in the as-deformed condition. In the course of recrystallization, the initial duplex fibre texture is replaced by a strong 〈111〉 fibre recrystallization texture.......The microstructure of the oxide dispersion strengthened ferritic steel PM2000 has been investigated after compression by dynamic plastic deformation to a strain of 2.1 and after subsequent annealing at 715 °C. Nanoscale lamellae, exhibiting a strong 〈100〉 + 〈111〉 duplex fibre texture, form during...... dynamic plastic deformation. Different boundary spacings and different stored energy densities for regions belonging to either of the two fibre texture components result in a quite heterogeneous deformation microstructure. Upon annealing, preferential recovery and preferential nucleation of...

  10. Free-energy studies reveal a possible mechanism for oxidation-dependent inhibition of MGL

    Science.gov (United States)

    Scalvini, Laura; Vacondio, Federica; Bassi, Michele; Pala, Daniele; Lodola, Alessio; Rivara, Silvia; Jung, Kwang-Mook; Piomelli, Daniele; Mor, Marco

    2016-01-01

    The function of monoacylglycerol lipase (MGL), a key actor in the hydrolytic deactivation of the endocannabinoid 2-arachidonoyl-sn-glycerol (2AG), is tightly controlled by the cell’s redox state: oxidative signals such as hydrogen peroxide suppress MGL activity in a reversible manner through sulfenylation of the peroxidatic cysteines, C201 and C208. Here, using as a starting point the crystal structures of human MGL (hMGL), we present evidence from molecular dynamics and metadynamics simulations along with high-resolution mass spectrometry studies indicating that sulfenylation of C201 and C208 alters the conformational equilibrium of the membrane-associated lid domain of MGL to favour closed conformations of the enzyme that do not permit the entry of substrate into the active site. PMID:27499063

  11. Quantitative analysis of some mechanisms affecting the yield of oxidative phosphorylation: dependence upon both fluxes and forces.

    Science.gov (United States)

    Rigoulet, M; Leverve, X; Fontaine, E; Ouhabi, R; Guérin, B

    1998-07-01

    in rat, it was found that non-ohmic proton leak was increased, while ohmic leak was unchanged. Moreover, an increase in redox slipping was also involved, leading to a complex picture. However, the respective role of these two mechanisms may be deduced from their intrinsic properties. For each steady state condition, the quantitative effect of these two mechanisms in the decrease of oxidative phosphorylation efficiency depends on the values of different fluxes or forces involved. (4) Finally the comparison of the thermokinetic data in view of the three dimensional-structure of some pumps (X-ray diffraction) also gives some information concerning the putative mechanism of coupling (i.e. redox loop or proton pump) and their kinetic control versus regulation of mitochondrial oxidative phosphorylation. PMID:9746311

  12. N2O production by ammonia oxidizing bacteria in an enriched nitrifying sludge linearly depends on inorganic carbon concentration.

    Science.gov (United States)

    Peng, Lai; Ni, Bing-Jie; Ye, Liu; Yuan, Zhiguo

    2015-05-01

    The effect of inorganic carbon (IC) on nitrous oxide (N2O) production by ammonia oxidizing bacteria (AOB) was investigated over a concentration range of 0-12 mmol C/L, encompassing typical IC levels in a wastewater treatment reactors. The AOB culture was enriched along with nitrite-oxidizing bacteria (NOB) in a sequencing batch reactor (SBR) to perform complete nitrification. Batch experiments were conducted with continuous carbon dioxide (CO2) stripping or at controlled IC concentrations. The results revealed a linear relationship between N2O production rate (N2OR) and IC concentration (R(2) = 0.97) within the IC range studied, suggesting a substantial effect of IC on N2O production by AOB. Similar results were also obtained with an AOB culture treating anaerobic sludge digestion liquor. The fundamental mechanism responsible for this dependency is unclear; however, in agreement with previous studies, it was observed that the ammonia oxidation rate (AOR) was also influenced by the IC concentration, which could be well described by the Monod kinetics. These resulted in an exponential relationship between N2OR and AOR, as previously observed in experiments where AOR was altered by varying dissolved oxygen and ammonia concentrations. It is therefore possible that IC indirectly affected N2OR by causing a change in AOR. The observation in this study indicates that alkalinity (mostly contributed by IC) could be a significant factor influencing N2O production and should be taken into consideration in estimating and mitigating N2O emissions in wastewater treatment systems. PMID:25706224

  13. Temperature dependent thermoelectric properties of chemically derived gallium zinc oxide thin films

    KAUST Repository

    Barasheed, Abeer Z.

    2013-01-01

    In this study, the temperature dependent thermoelectric properties of sol-gel prepared ZnO and 3% Ga-doped ZnO (GZO) thin films have been explored. The power factor of GZO films, as compared to ZnO, is improved by nearly 17% at high temperature. A stabilization anneal, prior to thermoelectric measurements, in a strongly reducing Ar/H2 (95/5) atmosphere at 500°C was found to effectively stabilize the chemically derived films, practically eliminating hysteresis during thermoelectric measurements. Subtle changes in the thermoelectric properties of stabilized films have been correlated to oxygen vacancies and excitonic levels that are known to exist in ZnO-based thin films. The role of Ga dopants and defects, formed upon annealing, in driving the observed complex temperature dependence of the thermoelectric properties is discussed. © The Royal Society of Chemistry 2013.

  14. Nitric oxide mediates the fungal elicitor-induced Taxol biosynthesis of Taxus chinensis suspension cells through the reactive oxygen species-dependent and-independent signal pathways

    Institute of Scientific and Technical Information of China (English)

    XU Maojun; DONG Jufang

    2006-01-01

    Nitric oxide and reactive oxygen species are two important signal molecules that play key roles in plant defense responses. Nitric oxide generation and oxidative burst and accumulation of reactive oxygen species are the early reactions of Taxus chinensis suspension cells to fungal elicitor prepared from the cell walls of Penicillium citrinum. In order to investigate the relationship and/or interactions of nitric oxide and reactive oxygen species in the elicitor-induced Taxol biosynthesis of T. chinensis suspension cells, we treated the cells with nitric oxide specific scavenger 2-4-carboxyphenyl-4,4,5,5-tetra- methylimidazoline-1-oxyl-3-oxide (cPITO), nitric oxide synthase inhibitor S,S(-1,3-phenylene-bis(1,2-eth- anediyl)-bis-isothiourea (PBITU), membrane NAD(P) H oxidase inhibitor diphenylene iodonium (DPI), superoxide dismutases (SOD) and catalase. The results show that pretreatment of T. chinensis cells with cPITO and DPI inhibited not only the elicitor-induced nitric oxide biosynthesis and oxidative burst, but also the elicitor-induced Taxol production, suggesting that both nitric oxide and reactive oxygen species are involved in elicitor-induced Taxol biosynthesis. Furthermore, pretreatment of the cells with cPITO and PBITU suppressed the elicitor-induced oxidative burst, indicating that the oxidative burst might be dependent on NO. Application of nitric oxide via its donor sodium nitroprusside (SNP) triggered Taxol biosynthesis of T. chinensis cells. The nitric oxide-induced Taxol production was suppressed by DPI, showing that the oxidative burst is involved in NO-triggered Taxol biosynthesis. However, nitric oxide and the fungal elicitor induced Taxol biosynthesis even though the accumulation of reactive oxygen species wass completely abolished in T. chinensis cells. Our data show that nitric oxide may mediate the elicitor-induced Taxol biosynthesis of T. chinensis suspension cells through both reactive oxygen species-dependent and -independent signal

  15. Nano-crystals of cerium–hafnium binary oxide: Their size-dependent structure

    Energy Technology Data Exchange (ETDEWEB)

    Raitano, Joan M. [Department of Applied Physics and Applied Mathematics, Materials Science and Engineering Program, Columbia University, New York, NY 10027 (United States); Khalid, Syed [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, NY 11973 (United States); Marinkovic, Nebojsa [Chemical Engineering Department, Columbia University, 500 W 120th St, Mudd 801, New York, NY 10027 (United States); Chan, Siu-Wai, E-mail: sc174@columbia.edu [Department of Applied Physics and Applied Mathematics, Materials Science and Engineering Program, Columbia University, New York, NY 10027 (United States)

    2015-09-25

    Highlights: • (1 − x)CeO{sub 2}–xHfO{sub 2} was precipitated (0 < x < 1) and calcined in air. • For x ⩽ 0.14, crystallites ⩽140 nm in size exhibit only the fluorite structure. • This low hafnia solubility is attributable to no auto-reduction (Ce{sup 3+} = 0). • The low solubility is also due to the high temperature required for homogenization. • Coarsening is lessened as Hf{sup 4+} ions slow cation diffusion in these crystallites. - Abstract: Cerium oxide (CeO{sub 2}, “ceria”) and hafnium oxide (HfO{sub 2}, “hafnia”) were aqueously co-precipitated and subsequently calcined to allow for homogenization. The size of the (1−x)CeO{sub 2}–xHfO{sub 2} crystallites, determined by the Scherrer equation, varied from 140 nm for x = 0 to 15 nm for x = 0.73. For x ⩽ 0.14, only cubic structures are visible in X-ray diffractograms, and the lattice parameters are consistent with the values expected for structurally cubic solid solutions of hafnia in ceria. At x = 0.26, tetragonal and monoclinic phases nucleated with the former not being observed in the bulk phase diagram for ceria–hafnia. Therefore, the solubility limit of the cubic structure is between x = 0.14 and x = 0.26 for 40–61 nm crystallites, the sizes of these respective compositions. More specifically, for the 40 nm crystallites of x = 0.26 (1 − x)CeO{sub 2}–xHfO{sub 2}, 15% of the hafnia remains in a structurally cubic solid solution with ceria based on the observed cubic lattice parameter. The compositional domain for the cubic fluorite structure in this study is narrower than other nanostructured (1 − x)CeO{sub 2}–xHfO{sub 2} studies, especially studies with crystallite sizes less than 10 nm, but wider than observed in the bulk and helps to expand the size regime over which the relationship between crystallite size and phase stability is known. The extent of this cubic-structure domain is mainly attributable to the intermediate crystallite size and the roughly zero Ce{sup 3

  16. Atomic layer deposited lithium aluminum oxide: (In)dependency of film properties from pulsing sequence

    Energy Technology Data Exchange (ETDEWEB)

    Miikkulainen, Ville, E-mail: ville.miikkulainen@helsinki.fi; Nilsen, Ola; Fjellvåg, Helmer [Centre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo, P.O. Box 1126 Blindern, NO-0318 Oslo (Norway); Li, Han; King, Sean W. [Intel Corporation, 5200 NE Elam Young Parkway, Hillsboro, Oregon 97124 (United States); Laitinen, Mikko; Sajavaara, Timo [Department of Physics, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä (Finland)

    2015-01-01

    Atomic layer deposition (ALD) holds markedly high potential of becoming the enabling method for achieving the three-dimensional all-solid-state thin-film lithium ion battery (LiB). One of the most crucial components in such a battery is the electrolyte that needs to hold both low electronic conductivity and at least fair lithium ion conductivity being at the same time pinhole free. To obtain these desired properties in an electrolyte film, one necessarily has to have a good control over the elemental composition of the deposited material. The present study reports on the properties of ALD lithium aluminum oxide (Li{sub x}Al{sub y}O{sub z}) thin films. In addition to LiB electrolyte applications, Li{sub x}Al{sub y}O{sub z} is also a candidate low dielectric constant (low-k) etch stop and diffusion barrier material in nanoelectronics applications. The Li{sub x}Al{sub y}O{sub z} films were deposited employing trimethylaluminum-O{sub 3} and lithium tert-butoxide-H{sub 2}O for Al{sub 2}O{sub 3} and Li{sub 2}O/LiOH, respectively. The composition was aimed to be controlled by varying the pulsing ratio of those two binary oxide ALD cycles. The films were characterized by several methods for composition, crystallinity and phase, electrical properties, hardness, porosity, and chemical environment. Regardless of the applied pulsing ratio of Al{sub 2}O{sub 3} and Li{sub 2}O/LiOH, all the studied ALD Li{sub x}Al{sub y}O{sub z} films of 200 and 400 nm in thickness were polycrystalline in the orthorhombic β-LiAlO{sub 2} phase and also very similar to each other with respect to composition and other studied properties. The results are discussed in the context of both fundamental ALD chemistry and applicability of the films as thin-film LiB electrolytes and low-k etch stop and diffusion barriers.

  17. Morphology dependent dye-sensitized solar cell properties of nanocrystalline zinc oxide thin films

    International Nuclear Information System (INIS)

    Research highlights: → Nano-crystalline zinc oxide thin films were electrosynthesized from an aqueous zinc acetate [Zn(CH3COO)2.2H2O] solution onto FTO coated conducting glass substrates using two different electrochemical routes, namely (i) without an organic surfactant and (ii) with an organic surfactant, viz. PVA (poly-vinyl alcohol) or SDS (sodium dodecyl sulfate). → The reproducibility of the catalytic activity of the SDS and PVA surfactants in the modification of the morphologies was observed. → Vertically aligned nest-like and compact structures were observed from the SDS and PVA mediated films, respectively, while the grain size in the ZnO thin films without an organic surfactant was observed to be ∼150 nm. → The dye sensitized ZnO electrodes displayed excellent properties in the conversion process from light to electricity. The efficiencies of the surfactant mediated nanocrystalline ZnO thin films, viz. ZnO:SDS and ZnO:PVA, sensitized with ruthenium-II (N3) dye were observed to be 0.49% and 0.27%, respectively. - Abstract: Nano-crystalline zinc oxide thin films were electrosynthesized with an aqueous zinc acetate [Zn(CH3COO)2.2H2O] solution on to FTO coated glass substrates. Two different electrochemical baths were used, namely (i) without an organic surfactant and (ii) with an organic surfactant, viz. PVA (poly-vinyl alcohol) and SDS (sodium dodecyl sulfate). The organic surfactants played an important role in modifying the surface morphology, which influenced the size of the crystallites and dye-sensitized solar cell (DSSC) properties. The vertically aligned thin and compact hexagonal crystallites were observed with SDS mediated films, while the grain size in the films without an organic surfactant was observed to be ∼150 nm. The conversion efficiencies of the ZnO:SDS:Dye and ZnO:PVA:Dye thin films were observed to be 0.49% and 0.27%, respectively.

  18. Solubility product of tetravalent neptunium hydrous oxide and its ionic strength dependence

    International Nuclear Information System (INIS)

    Full text of publication follows: Solubility products (Ksp) are key parameters in the context of reliable assessment of actinides migration in the repository conditions of high level radioactive waste. Neptunium (Np(IV)) is one of the most important actinide elements in the assessment, because of its inventory and the long half-life. A few previous data for Np(IV) solubility are varied widely due to experimental difficulties related to the extremely low solubility. We carried out batch-type experiments under nitrogen atmosphere using a glovebox. Np(V) was reduced to Np(III) by bubbling 0.5 ppm H2 / N2 gas through the solution for 30 days in the presence of platinum black as catalyst. After reducing treatment, the Np(III) converted to Np(IV) by auto-oxidation within approximately three days. The solubilities of the Np(IV) were measured in the pHc ranging from 2 to 4, at room temperature (23 ± 2 deg. C), in ionic strength(I) = 0.1, 0.5, 1.0 and 2.0 M NaClO4. The equilibrium condition was confirmed by over-saturation and under-saturation method. After the equilibrium, the pHc and the Eh value of the suspension were measured. The suspension was then filtered using a filter with a NMWL of 3000 (less than 2 nmΦ). The Np radio activity in the filtrate was determined by alpha spectrometry and absorption spectra of Np(IV). The solubility decreased with increasing pHc and the hydrolysis species are predominantly formed. From the obtained results, the solubility products (Ksp) of Np hydroxide, for the reaction, NpO2 . xH2O ↔ Np4+ + 4OH- + (x-2)H2O, at I = 0.1, 0.5, 1.0 and 2.0 were determined by using formation constants (βn(I)), which were determined for the reaction, Np4+ + nOH- ↔ Np(OH)n(4-n)+. By using the specific interaction theory (SIT), the solubility product of tetravalent Np hydrous oxide is calculated to be log Ksp0 = -56.8 ± 0.3, and the ion interaction coefficient ε(Np4+, ClO4-) was also evaluated to be 0.81 ± 0.18. (authors)

  19. Size-Dependent Accumulation of PEGylated Silane-Coated Magnetic Iron Oxide Nanoparticles in Murine Tumors

    DEFF Research Database (Denmark)

    Larsen, Esben Kjær Unmack; Nielsen, T.; Wittenborn, T.;

    2009-01-01

    two distinct size subpopulations of 20 and 40 nm mean diameters with increased phagocytic uptake observed for the 40 nm size range in vitro. MRI detection revealed greater iron accumulation in murine tumors for 40 nm nanoparticles after intravenous injection. The enhanced MRI contrast of the larger......Magnetic nanoparticles (MNP) can be used as contrast-enhancing agents to visualize tumors by magnetic resonance imaging (MRI). Here we describe an easy synthesis method of magnetic nanoparticles coated with polyethylene glycol (PEG) and demonstrate size-dependent accumulation in murine tumors...

  20. Substrate dependant capacitive performance of spray pyrolysed titanium oxide (TiO2) thin films

    Science.gov (United States)

    Fugare, B. Y.; Ingole, R. S.; Ambare, R. C.; Lokhande, B. J.

    2016-04-01

    Using 60 ml, 0.06 M aqueous solution of potassium titanium oxalate (pto), thin films of titanium oxide were prepared by using well known spray pyrolysis technique. Depositions of the films carried out at 723° K by maintain the spray rate 12 Cc/min. prepared thin films were characterized structurally, morphologically and electrochemically. Sample shows tetragonal crystal structure with rutile as prominent phase at very low deposition temperature. SEM morphology shows porous, dense, nanorods and nanoplates like morphology. The electrochemical cyclic voltammetery shows mixed capacitive behavior. The specific capacitance values observed from cyclic voltammetery in 1 M NaOH are 2497.19, 29.60, 424.22 F/g. for the electrode deposited on copper, FTO and stainless steel (SS) respectively. Charge discharge behavior was observed for the samples deposited on stainless steel gives specific energy (SE), specific power (SP) and efficiency (η) are 43.25 Wh/kg, 35.25 kW/kg and 98.22 % respectively. Impedance study was carried out in the frequency range 1 mHz to 1 MHz exhibits very less internal resistance 1.066 Ohm for the deposited electrode.

  1. Odorant-dependent generation of nitric oxide in Mammalian olfactory sensory neurons.

    Directory of Open Access Journals (Sweden)

    Daniela Brunert

    Full Text Available The gaseous signalling molecule nitric oxide (NO is involved in various physiological processes including regulation of blood pressure, immunocytotoxicity and neurotransmission. In the mammalian olfactory bulb (OB, NO plays a role in the formation of olfactory memory evoked by pheromones as well as conventional odorants. While NO generated by the neuronal isoform of NO synthase (nNOS regulates neurogenesis in the olfactory epithelium, NO has not been implicated in olfactory signal transduction. We now show the expression and function of the endothelial isoform of NO synthase (eNOS in mature olfactory sensory neurons (OSNs of adult mice. Using NO-sensitive micro electrodes, we show that stimulation liberates NO from isolated wild-type OSNs, but not from OSNs of eNOS deficient mice. Integrated electrophysiological recordings (electro-olfactograms or EOGs from the olfactory epithelium of these mice show that NO plays a significant role in modulating adaptation. Evidence for the presence of eNOS in mature mammalian OSNs and its involvement in odorant adaptation implicates NO as an important new element involved in olfactory signal transduction. As a diffusible messenger, NO could also have additional functions related to cross adaptation, regeneration, and maintenance of MOE homeostasis.

  2. Surface ligand dependent toxicity of zinc oxide nanoparticles in HepG2 cell model

    International Nuclear Information System (INIS)

    Physicochemical properties of nanoparticles (NP) strongly affect their influence on cell behaviour, but can be significantly distorted by interactions with the proteins present in biological solutions. In this study we show how different surface functionalities of zinc oxide (ZnO) NP lead to changes in the size distribution and dissolution of the NP in serum containing cell culture media and how this impacts on NP toxicity. NPs capped with weakly bound large proteins undergo substantial transformations due to the exchange of the original surface ligands to the components of the cell culture media. Conversely, NP capped with a tight monolayer of small organic molecules or with covalently conjugated proteins show significantly higher stability. These differences in ligand exchange also affect the toxicity of the NP to the HepG2 liver cell model, with the NP capped with small organic molecules being more toxic than those capped with large proteins. This study highlights the importance of characterising NPs in biological media and the effect the media has during in-vitro analysis.

  3. Sex-Dependent Depression-Like Behavior Induced by Respiratory Administration of Aluminum Oxide Nanoparticles.

    Science.gov (United States)

    Zhang, Xin; Xu, Yan; Zhou, Lian; Zhang, Chengcheng; Meng, Qingtao; Wu, Shenshen; Wang, Shizhi; Ding, Zhen; Chen, Xiaodong; Li, Xiaobo; Chen, Rui

    2015-12-01

    Ultrafine aluminum oxide, which are abundant in ambient and involved occupational environments, are associated with neurobehavioral alterations. However, few studies have focused on the effect of sex differences following exposure to environmental Al₂O₃ ultrafine particles. In the present study, male and female mice were exposed to Al₂O₃ nanoparticles (NPs) through a respiratory route. Only the female mice showed depression-like behavior. Although no obvious pathological changes were observed in mice brain tissues, the neurotransmitter and voltage-gated ion channel related gene expression, as well as the small molecule metabolites in the cerebral cortex, were differentially modulated between male and female mice. Both mental disorder-involved gene expression levels and metabolomics analysis results strongly suggested that glutamate pathways were implicated in sex differentiation induced by Al₂O₃ NPs. Results demonstrated the potential mechanism of environmental ultrafine particle-induced depression-like behavior and the importance of sex dimorphism in the toxic research of environmental chemicals. PMID:26690197

  4. Sex-Dependent Depression-Like Behavior Induced by Respiratory Administration of Aluminum Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Xin Zhang

    2015-12-01

    Full Text Available Ultrafine aluminum oxide, which are abundant in ambient and involved occupational environments, are associated with neurobehavioral alterations. However, few studies have focused on the effect of sex differences following exposure to environmental Al2O3 ultrafine particles. In the present study, male and female mice were exposed to Al2O3 nanoparticles (NPs through a respiratory route. Only the female mice showed depression-like behavior. Although no obvious pathological changes were observed in mice brain tissues, the neurotransmitter and voltage-gated ion channel related gene expression, as well as the small molecule metabolites in the cerebral cortex, were differentially modulated between male and female mice. Both mental disorder-involved gene expression levels and metabolomics analysis results strongly suggested that glutamate pathways were implicated in sex differentiation induced by Al2O3 NPs. Results demonstrated the potential mechanism of environmental ultrafine particle-induced depression-like behavior and the importance of sex dimorphism in the toxic research of environmental chemicals.

  5. Electrokinetic Properties of the Pristine and Oxidized MWCNT Depending on the Electrolyte Type and Concentration.

    Science.gov (United States)

    Skwarek, Ewa; Bolbukh, Yuliia; Tertykh, Valentyn; Janusz, Władysław

    2016-12-01

    Electrostatic stabilization is reduced in its efficiency in an electrolyte-containing environment. The effect of electrolyte concentration is mostly described as negative factor for dispersion stabilization. Usually, zeta potential and physical stability decrease at increasing electrolyte concentration. The purpose of the present study was to measure the surface properties of nanotubes in aqueous solution of monovalent electrolytes at different concentration. Characteristics such as size distribution, surface chemistry, surface charge, and dispersability in aqueous phase have been identified. Hydrodynamic size and zeta potential in aqueous multiwalled carbon nanotube (MWCNT) suspensions were determined at different pH with the desired concentrations of electrolyte of the cationic group (NaCl, KCl, CsCl) and the anionic group (NaClO4). The correlations between the response of the surface functionality of pristine and oxidized multiwalled carbon nanotubes and electrical double layer (EDL) forming at different ionic environments in the vicinity of a nanotube surface were determined. The nanotube dispersion stabilization was found to be more affected by ion size and pH medium then electrolyte concentration. The data obtained confirms the predominant role of surface reactions. The most stable dispersion of nanotubes was achieved in KCl electrolyte solution at less negative charge of the surface. PMID:27009533

  6. Amorphous film thickness dependence for epitaxy of perovskite oxide films under excimer laser irradiation

    International Nuclear Information System (INIS)

    We have studied the epitaxial growth of perovskite manganite LaMnO3 (LMO) on SrTiO3(1 0 0) in the excimer laser assisted metal organic deposition process. The LMO was preferentially grown from the substrate surface by the KrF laser irradiation. The study of amorphous LMO film thickness dependence on epitaxial growth under the excimer laser irradiation revealed that the photo-thermal heating effect strongly depended on the amorphous film thickness due to a low thermal conductivity of amorphous LMO: the ion-migration for chemical bond-forming at the reaction interface would be strongly enhanced in the amorphous LMO film with the large film thickness about 210 nm. On the other hand, the photo-chemical effect occurred efficiently for the amorphous film thickness in the range of 35-210 nm. These results indicate that the epitaxial growing rate was dominated by the photo-thermal heating after the photo-chemical activation at the growth interface.

  7. Dose-dependent onset and cessation of action of inhaled budesonide on exhaled nitric oxide and symptoms in mild asthma

    Science.gov (United States)

    Kharitonov, S; Donnelly, L; Montuschi, P; Corradi, M; Collins, J; Barnes, P

    2002-01-01

    Background: Dose dependent anti-inflammatory effects of inhaled corticosteroids in asthma are difficult to demonstrate in clinical practice. The anti-inflammatory effect of low dose inhaled budesonide on non-invasive exhaled markers of inflammation and oxidative stress were assessed in patients with mild asthma. Methods: 28 patients entered a double blind, placebo controlled, parallel group study and were randomly given either 100 or 400 µg budesonide or placebo once daily, inhaled from a dry powder inhaler (Turbohaler), for 3 weeks followed by 1 week without treatment. Exhaled nitric oxide (NO), exhaled carbon monoxide (CO), nitrite/nitrate, S-nitrosothiols, and 8-isoprostanes in exhaled breath condensate were measured four times during weeks 1 and 4, and once a week during weeks 2 and 3. Results: A dose-dependent speed of onset and cessation of action of budesonide was seen on exhaled NO and asthma symptoms. Treatment with 400 µg/day reduced exhaled NO faster (–2.06 (0.37) ppb/day) than 100 µg/day (–0.51 (0.35) ppb/day; p<0.01). The mean difference between the effect of 100 and 400 µg budesonide was –1.55 ppb/day (95% CI –2.50 to –0.60). Pretreatment NO levels were positively related to the subsequent speed of reduction during the first 3–5 days of treatment. Faster recovery of exhaled NO was seen after stopping treatment with budesonide 400 µg/day (1.89 (1.43) ppb/day) than 100 µg/day (0.49 (0.34) ppb/day, p<0.01). The mean difference between the effect of 100 and 400 µg budesonide was 1.40 ppb/day (95% CI –0.49 to 2.31). Symptom improvement was dose-dependent, although symptoms returned faster in patients treated with 400 µg/day. A significant reduction in exhaled nitrite/nitrate and S-nitrosothiols after budesonide treatment was not dose-dependent. There were no significant changes in exhaled CO or 8-isoprostanes in breath condensate. Conclusion: Measurement of exhaled NO levels can indicate a dose-dependent onset and cessation of anti

  8. Apolipoprotein B of low-density lipoprotein impairs nitric oxide-mediated endothelium-dependent relaxation in rat mesenteric arteries

    DEFF Research Database (Denmark)

    Zhang, Yaping; Zhang, Wei; Edvinsson, Lars; Xu, Cang-Bao

    2014-01-01

    Apolipoprotein B (ApoB) of low-density lipoprotein (LDL) causes endothelial dysfunction in the initial stage of atherogenesis. The present study was designed to explore the underlying molecular mechanisms involved. Rat mesenteric arteries were organ cultured in the presence of different concentra......Apolipoprotein B (ApoB) of low-density lipoprotein (LDL) causes endothelial dysfunction in the initial stage of atherogenesis. The present study was designed to explore the underlying molecular mechanisms involved. Rat mesenteric arteries were organ cultured in the presence of different...... concentrations of ApoB or LDL. Vasodilation induced by acetylcholine was monitored by a sensitive myograph. Nitric oxide (NO), endothelium-dependent hyperpolarizing factor (EDHF) and prostacyclin (PGI2) pathways were characterized by using specific pathway inhibitors. Real-time PCR and immunohistochemistry with......-dependently attenuated the endothelium-dependent vasodilation. Immunohistochemistry staining of endothelial cell marker CD31 was weaker in the presence of LDL, indicating that LDL induced damage to the endothelium. Using the pathway specific inhibitors demonstrated that LDL-induced impairing vasodilation was mainly due...

  9. Temperature-dependent bias-stress-induced electrical instability of amorphous indium-gallium-zinc-oxide thin-film transistors

    Science.gov (United States)

    Qian, Hui-Min; Yu, Guang; Lu, Hai; Wu, Chen-Fei; Tang, Lan-Feng; Zhou, Dong; Ren, Fang-Fang; Zhang, Rong; Zheng, You-Liao; Huang, Xiao-Ming

    2015-07-01

    The time and temperature dependence of threshold voltage shift under positive-bias stress (PBS) and the following recovery process are investigated in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. It is found that the time dependence of threshold voltage shift can be well described by a stretched exponential equation in which the time constant τ is found to be temperature dependent. Based on Arrhenius plots, an average effective energy barrier Eτstress = 0.72 eV for the PBS process and an average effective energy barrier Eτrecovery = 0.58 eV for the recovery process are extracted respectively. A charge trapping/detrapping model is used to explain the threshold voltage shift in both the PBS and the recovery process. The influence of gate bias stress on transistor performance is one of the most critical issues for practical device development. Project supported by the National Basic Research Program of China (Grant Nos. 2011CB301900 and 2011CB922100) and the Priority Academic Program Development of Jiangsu Higher Education Institutions, China

  10. Nitric oxide regulates BDNF release from nodose ganglion neurons in a pattern-dependent and cGMP-independent manner.

    Science.gov (United States)

    Hsieh, Hui-ya; Robertson, Carolyn L; Vermehren-Schmaedick, Anke; Balkowiec, Agnieszka

    2010-05-01

    Activity of arterial baroreceptors is modulated by neurohumoral factors, including nitric oxide (NO), released from endothelial cells. Baroreceptor reflex responses can also be modulated by NO signaling in the brainstem nucleus tractus solitarius (NTS), the primary central target of cardiovascular afferents. Our recent studies indicate that brain-derived neurotrophic factor (BDNF) is abundantly expressed by developing and adult baroreceptor afferents in vivo, and released from cultured nodose ganglion (NG) neurons by patterns of baroreceptor activity. Using electrical field stimulation and ELISA in situ, we show that exogenous NO nearly abolishes BDNF release from newborn rat NG neurons in vitro stimulated with single pulses delivered at 6 Hz, but not 2-pulse bursts delivered at the same 6-Hz frequency, that corresponds to a rat heart rate. Application of L-NAME, a specific inhibitor of endogenous NO synthases, does not have any significant effect on activity-dependent BDNF release, but leads to upregulation of BDNF expression in an activity-dependent manner. The latter effect suggests a novel mechanism of homeostatic regulation of activity-dependent BDNF expression with endogenous NO as a key player. The exogenous NO-mediated effect does not involve the cGMP-protein kinase G (PKG) pathway, but is largely inhibited by N-ethylmaleimide and TEMPOL that are known to prevent S-nitrosylation. Together, our current data identify previously unknown mechanisms regulating BDNF availability, and point to NO as a likely regulator of BDNF at baroafferent synapses in the NTS. PMID:19937808

  11. Seasonal dependence of the oxidation capacity of the city of Santiago de Chile

    Science.gov (United States)

    Elshorbany, Y. F.; Kleffmann, J.; Kurtenbach, R.; Lissi, E.; Rubio, M.; Villena, G.; Gramsch, E.; Rickard, A. R.; Pilling, M. J.; Wiesen, P.

    2010-12-01

    The oxidation capacity of the highly polluted urban area of Santiago de Chile has been evaluated during a winter measurement campaign from May 25 to June 07, 2005, with the results compared and contrasted with those previously evaluated during a summer campaign from March 8 to 20, 2005. The OH radical budget was evaluated in both campaigns employing a simple quasi-photostationary state model (PSS) constrained with simultaneous measurements of HONO, HCHO, O 3, NO, NO 2, j(O 1D), j(NO 2), 13 alkenes and meteorological parameters. In addition, a zero dimensional photochemical box model based on the Master Chemical Mechanism (MCMv3.1) has been used for the analysis of the radical budgets and concentrations of OH, HO 2 and RO 2. Besides the above parameters, the MCM model has been constrained by the measured CO and other volatile organic compounds (VOCs) including alkanes and aromatics. Total production and destruction rates of OH and HO 2 in winter are about two times lower than that during summer. Simulated OH levels by both PSS and MCM models are similar during the daytime for both winter and summer indicating that the primary OH sources and sinks included in the simple PSS model are predominant. On a 24 h basis, HONO photolysis was shown to be the most important primary OH radical source comprising 81% and 52% of the OH initiation rate during winter and summer, respectively followed by alkene ozonolysis (12.5% and 29%), photolysis of HCHO (6.1% and 15%), and photolysis of O 3 (budgets are also discussed.

  12. Magnetic state dependent transient lateral photovoltaic effect in patterned ferromagnetic metal-oxide-semiconductor films

    Directory of Open Access Journals (Sweden)

    Isidoro Martinez

    2015-11-01

    Full Text Available We investigate the influence of an external magnetic field on the magnitude and dephasing of the transient lateral photovoltaic effect (T-LPE in lithographically patterned Co lines of widths of a few microns grown over naturally passivated p-type Si(100. The T-LPE peak-to-peak magnitude and dephasing, measured by lock-in or through the characteristic time of laser OFF exponential relaxation, exhibit a notable influence of the magnetization direction of the ferromagnetic overlayer. We show experimentally and by numerical simulations that the T-LPE magnitude is determined by the Co anisotropic magnetoresistance. On the other hand, the magnetic field dependence of the dephasing could be described by the influence of the Lorentz force acting perpendiculary to both the Co magnetization and the photocarrier drift directions. Our findings could stimulate the development of fast position sensitive detectors with magnetically tuned magnitude and phase responses.

  13. Bacteria-mediated precursor-dependent biosynthesis of superparamagnetic iron oxide and iron sulfide nanoparticles.

    Science.gov (United States)

    Bharde, Atul A; Parikh, Rasesh Y; Baidakova, Maria; Jouen, Samuel; Hannoyer, Baetrice; Enoki, Toshiaki; Prasad, B L V; Shouche, Yogesh S; Ogale, Satish; Sastry, Murali

    2008-06-01

    The bacterium Actinobacter sp. has been shown to be capable of extracellularly synthesizing iron based magnetic nanoparticles, namely maghemite (gamma-Fe2O3) and greigite (Fe3S4) under ambient conditions depending on the nature of precursors used. More precisely, the bacterium synthesized maghemite when reacted with ferric chloride and iron sulfide when exposed to the aqueous solution of ferric chloride-ferrous sulfate. Challenging the bacterium with different metal ions resulted in induction of different proteins, which bring about the specific biochemical transformations in each case leading to the observed products. Maghemite and iron sulfide nanoparticles show superparamagnetic characteristics as expected. Compared to the earlier reports of magnetite and greigite synthesis by magnetotactic bacteria and iron reducing bacteria, which take place strictly under anaerobic conditions, the present procedure offers significant advancement since the reaction occurs under aerobic condition. Moreover, reaction end products can be tuned by the choice of precursors used. PMID:18454562

  14. SOx oxidation and volatile aerosol in aircraft exhaust plumes depend on fuel sulfur content

    Science.gov (United States)

    Miake-Lye, R. C.; Anderson, B. E.; Cofer, W. R.; Wallio, H. A.; Nowicki, G. D.; Ballenthin, J. O.; Hunton, D. E.; Knighton, W. B.; Miller, T. M.; Seeley, J. V.; Viggiano, A. A.

    Volatile and nonvolatile aerosols were measured in the wake of a B757 airliner in flight, in concert with measurements of gaseous SOx and CO2 emissions, while the airplane was burning fuel with a sulfur content of either 72 parts per million by mass (ppmm) or 676 ppmm. The volatile aerosol number density exceeded that of the nonvolatile for both fuels and, while the nonvolatile (soot) component was largely insensitive to the fuel sulfur content, the volatile component depleted the gas-phase sulfur species with a condensed fraction that increased from 6% (low S) to 31% (high S). The large proportion of SOx in the aerosol phase and its nonlinear dependence on fuel sulfur content cannot be explained by known combustion mechanisms and has the potential for significant environmental effects.

  15. Hyperbaric oxygen preconditioning protects the lung against acute pancreatitis induced injury via attenuating inflammation and oxidative stress in a nitric oxide dependent manner.

    Science.gov (United States)

    Yu, Qi-Hong; Zhang, Pei-Xi; Liu, Ying; Liu, Wenwu; Yin, Na

    2016-09-01

    This study aimed to investigate the protective effects of hyperbaric oxygen preconditioning (HBO-PC) on acute pancreatitis AP associated acute lung injury (ALI) and the potential mechanisms. Rats were randomly divided into sham group, AP group, HBO-PC + AP group and HBO-PC + L-NAME group. Rats in HBO-PC + AP group received HBO-PC once daily for 3 days, and AP was introduced 24 h after last HBO-PC. In HBO-PC + L-NAME group, L-NAME (40 mg/kg) was intraperitoneally injected before each HBO-PC. At 24 h after AP, the blood lipase and amylase activities were measured; the lung and pancreas were harvested for pathological examination; the bronchoalveolar lavage fluid was collected for the detection of lactate dehydrogenase (LDH) and proteins; inflammatory factors, superoxide dismutase (SOD) activity and malonaldehyde content were measured in the lung and blood; the Nrf2, SOD-1 and haem oxygenase-1 (HO-1) protein expression was measured in the lung. The lung nitric oxide (NO) and NO synthase activity increased significantly after HBO-PC. HBO-PC was able to reduce blood lipase and amylase activities, improve lung and pancreatic pathology, decrease LDH and proteins in BALF, inhibit the production of inflammatory factors, reduce malonaldehyde content and increase SOD activity in the lung and blood as well as increase protein expression of Nrf2, SOD-1 and HO-1 in the lung. However, L-NAME before HBO-PC significantly attenuated protective effects of HBO-PC. HBO-PC is able to protect the lung against AP induced injury by attenuating inflammation and oxidative stress in the lung via a NO dependent manner. PMID:27453338

  16. Time-dependent effect of p-Aminophenol (PAP) toxicity in renal slices and development of oxidative stress

    International Nuclear Information System (INIS)

    p-Aminophenol (PAP), a metabolite of acetaminophen, is nephrotoxic. This study investigated PAP-mediated changes as a function of time that occur prior to loss of membrane integrity. Experiments further evaluated the development of oxidative stress by PAP. Renal slices from male Fischer 344 (F344) rats (N = 4-6) were exposed to 0.1, 0.25, and 0.5 mM PAP for 15-120 min under oxygen and constant shaking at 37 oC. Pyruvate-stimulated gluconeogenesis, adenine nucleotide levels, and total glutathione (GSH) levels were diminished in a concentration- and time-dependent manner prior to detection of a rise in lactate dehydrogenase (LDH) leakage. Glutathione disulfide (GSSG) levels were increased by PAP suggesting the induction of oxidative stress. Western blot analysis confirmed a rise in 4-hydroxynonenal (4-HNE)-adducted proteins in tissues exposed to 0.1 and 0.25 mM PAP for 90 min. The appearance of 4-HNE-adducted proteins at the 0.1 mM concentration of PAP occurred prior to development of increased LDH leakage. Pretreatment with 1 mM glutathione (GSH) for 30 min only partially reduced PAP toxicity as LDH values were less severely depleted relative to tissues not pretreated with GSH. In contrast, pretreatment for 15 min with 2 mM ascorbic acid completely protected against PAP toxicity. Further studies showed that ascorbic acid pretreatment prevented PAP-mediated depletion of GSH. In summary, PAP rapidly depletes GSH and adenine nucleotides and inhibits gluconeogenesis prior to a rise in LDH leakage. PAP induces oxidative stress as indicated by an increase in GSSG and 4-HNE-adducted proteins. Ascorbic acid pretreatment prevents PAP toxicity by maintaining GSH status

  17. Three-dimensional density-dependent flow and multicomponent reactive transport modeling of chlorinated solvent oxidation by potassium permanganate

    Science.gov (United States)

    Henderson, Thomas H.; Mayer, K. Ulrich; Parker, Beth L.; Al, Tom A.

    2009-05-01

    A popular method for the treatment of aquifers contaminated with chlorinated solvents is chemical oxidation based on the injection of potassium permanganate (KMnO 4). Both the high density (1025 gL - 1 ) and reactivity of the treatment solution influence the fate of permanganate (MnO 4) in the subsurface and affect the degree of contaminant treatment. The MIN3P multicomponent reactive transport code was enhanced to simulate permanganate-based remediation, to evaluate the pathways of MnO 4 utilization, and to assess the role of density contrasts for the delivery of the treatment solution. The modified code (MIN3P-D) provides a direct coupling between density-dependent fluid flow, solute transport, contaminant treatment, and geochemical reactions. The model is used to simulate a field trial of TCE oxidation in a sandy aquifer that is underlain by an aquitard. Three-dimensional simulations are conducted for a coupled reactive system comprised of ten aqueous components, two mineral phases, TCE (dissolved, adsorbed, and NAPL), reactive organic matter, and including ion exchange reactions. Model parameters are constrained by literature data and a detailed data set from the field site under investigation. The general spatial and transient evolution in observed concentrations of the oxidant, dissolved TCE, and reaction products are adequately reproduced by the simulations. The model elucidates the important role of density-induced flow and transport on the distribution of the treatment solution into NAPL containing regions located at the aquifer-aquitard interface. Model results further suggest that reactions that do not directly affect the stability of MnO 4 have a negligible effect on solution density and MnO 4 delivery.

  18. In Operando Identification of Geometrical-Site-Dependent Water Oxidation Activity of Spinel Co3O4.

    Science.gov (United States)

    Wang, Hsin-Yi; Hung, Sung-Fu; Chen, Han-Yi; Chan, Ting-Shan; Chen, Hao Ming; Liu, Bin

    2016-01-13

    Spinel Co3O4, comprising two types of cobalt ions: one Co(2+) in the tetrahedral site (Co(2+)(Td)) and the other two Co(3+) in the octahedral site (Co(3+)(Oh)), has been widely explored as a promising oxygen evolution reaction (OER) catalyst for water electrolysis. However, the roles of two geometrical cobalt ions toward the OER have remained elusive. Here, we investigated the geometrical-site-dependent OER activity of Co3O4 catalyst by substituting Co(2+)(Td) and Co(3+)(Oh) with inactive Zn(2+) and Al(3+), respectively. Following a thorough in operando analysis by electrochemical impedance spectroscopy and X-ray absorption spectroscopy, it was revealed that Co(2+)Td site is responsible for the formation of cobalt oxyhydroxide (CoOOH), which acted as the active site for water oxidation. PMID:26710084

  19. ROS-dependent anticandidal activity of zinc oxide nanoparticles synthesized by using egg albumen as a biotemplate

    International Nuclear Information System (INIS)

    Zinc oxide nanoparticles (ZnO NPs) have attracted great attention because of their superior optical properties and wide application in biomedical science. However, little is known about the anticandidal activity of ZnO NPs against Candida albicans (C. albicans). This study was designed to develop the green approach to synthesize ZnO NPs using egg white (denoted as EtZnO NPs) and investigated its possible mechanism of antimicrobial activity against C. albicans 077. It was also notable that anticandidal activity of EtZnO NPs is correlated with reactive oxygen species (ROS) production in a dose dependent manner. Protection of histidine against ROS clearly suggests the implication of ROS in anticandidal activity of EtZnO NPs. This green approach based on egg white-mediated synthesis of ZnO NPs paves the way for developing cost effective, eco-friendly and promising antimicrobial nanomaterial for applications in medicine. (paper)

  20. GaSb p-channel metal-oxide-semiconductor field-effect transistor and its temperature dependent characteristics

    International Nuclear Information System (INIS)

    GaSb p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with an atomic layer deposited Al2O3 gate dielectric and a self-aligned Si-implanted source/drain are experimentally demonstrated. Temperature dependent electrical characteristics are investigated. Different electrical behaviors are observed in two temperature regions, and the underlying mechanisms are discussed. It is found that the reverse-bias pn junction leakage of the drain/substrate is the main component of the off-state drain leakage current, which is generation-current dominated in the low temperature regions and is diffusion-current dominated in the high temperature regions. Methods to further reduce the off-state drain leakage current are given. (paper)

  1. Structural studies and c dependence in La2-DyCaBa2Cu4+O type mixed oxide superconductors

    Indian Academy of Sciences (India)

    S Rayaprol; Krushna Mavani; C M Thaker; D S Rana; Keka Chakravorty; S K Paranjape; M Ramanadham; Nilesh A Kulkarni; D G Kuberkar

    2002-05-01

    A new series of mixed oxide superconductors with the stoichiometric composition La2-DyCaBa2Cu4+O ( = 0.0 - 0.5, = 2) has been studied for structural and superconductiong properties. Our earlier studies on La2-(Y/Er)CaBa2Cu4+O series, show a strong dependence of c on hole concentration (sh). In the present work, the results of the analysis of the neutron diffraction measurements at room temprerature on = 0.3 and 0.5 samples are reported. It is interesting to know that Ca substitutes for both La and Ba site with concomitant displacement of La onto Ba site. Superconductivity studies show that maximum c is obtained for = 0.5, = 1.0 sample (c ∼ 75 K), for La1.5Dy0.5Ca1Ba2Cu5O (La-2125).

  2. Phospho-silicate glass gated 4H-SiC metal-oxide-semiconductor devices: Phosphorus concentration dependence

    Science.gov (United States)

    Jiao, C.; Ahyi, A. C.; Xu, C.; Morisette, D.; Feldman, L. C.; Dhar, S.

    2016-04-01

    The correlation between phosphorus concentration in phospho-silicate glass (PSG) gate dielectrics and electrical properties of 4H-SiC MOS devices has been investigated. Varying P uptake in PSG is achieved by changing the POCl3 post-oxidation annealing temperature. The density of interface traps (Dit) at the PSG/4H-SiC interface decreases as the amount of interfacial P increases. Most significantly, the MOSFET channel mobility does not correlate with Dit for all samples, which is highly unusual for SiC MOSFETs. Further analysis reveals two types of field-effect mobility (μfe) behavior, depending on the annealing temperature. Annealing at 1000 °C improves the channel mobility most effectively, with a peak value ˜105 cm2 V-1 s-1, and results in a surface phonon scattering limited mobility at high oxide field. On the other hand, PSG annealed at other temperatures results in a surface roughness scattering limited mobility at similar field.

  3. A magnetic-dependent protein corona of tailor-made superparamagnetic iron oxides alters their biological behaviors

    Science.gov (United States)

    Liu, Ziyao; Zhan, Xiaohui; Yang, Minggang; Yang, Qi; Xu, Xianghui; Lan, Fang; Wu, Yao; Gu, Zhongwei

    2016-03-01

    In recent years, it is becoming increasingly evident that once nanoparticles come into contact with biological fluids, a protein corona surely forms and critically affects the biological behaviors of nanoparticles. Herein, we investigate whether the formation of protein corona on the surface of superparamagnetic iron oxides (SPIOs) is influenced by static magnetic field. Under static magnetic field, there is no obvious variation in the total amount of protein adsorption, but the proportion of adsorbed proteins significantly changes. Noticeably, certain proteins including apolipoproteins, complement system proteins and acute phase proteins, increase in the protein corona of SPIOs in the magnetic field. More importantly, the magnetic-dependent protein corona of SPIOs enhances the cellular uptake of SPIOs into the normal cell line (3T3 cells) and tumor cell line (HepG2 cells), due to increased adsorption of apolipoprotein. In addition, SPIOs with the magnetic-dependent protein corona cause high cytotoxicity to 3T3 cells and HepG2 cells. This work discloses that superparamagnetism as a key feature of SPIOs affects the composition of protein corona to a large extent, which further alters the biological behaviors of SPIOs.In recent years, it is becoming increasingly evident that once nanoparticles come into contact with biological fluids, a protein corona surely forms and critically affects the biological behaviors of nanoparticles. Herein, we investigate whether the formation of protein corona on the surface of superparamagnetic iron oxides (SPIOs) is influenced by static magnetic field. Under static magnetic field, there is no obvious variation in the total amount of protein adsorption, but the proportion of adsorbed proteins significantly changes. Noticeably, certain proteins including apolipoproteins, complement system proteins and acute phase proteins, increase in the protein corona of SPIOs in the magnetic field. More importantly, the magnetic-dependent protein

  4. LET dependence of the production of oxidative DNA damage in mammalian cells

    International Nuclear Information System (INIS)

    Production of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in human leukemia HL-60 cells was examined upon irradiation with carbon, neon silicon ions. Cell suspension with the concentration of 1 x 107/ml was irradiated tinder air-saturated condition. After irradiation cells were subjected to the DNA extraction using isopropanol, separation of DNA strands by heat treatment, digestion into nucleosides with nuclease P1 and alkaline phosphatase. A single peak of 8-OHdG on a chromatogram was observed using newly installed ECD detector (Coulochem III; ESA, Inc. U.S.A.). Reproducibility was also greatly improved with this detector. 8-OHdG yield was decreased with increasing linear energy transfer (LET) for carbon and silicon beam. These results are in good accordance with those of dG solution which was previously reported by us. Ion species dependence in 8-OHdG yield was not so apparent through the comparison of carbon and neon beam with an LET of 80 keV/μm and neon and silicon beam with an LET of 150 keV/μm. (author)

  5. Estimation of frequency-dependent electrokinetic forces on tin oxide nanobelts in low frequency electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Surajit; Hesketh, Peter J, E-mail: surajitk@gatech.edu [George W Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2010-08-13

    A novel experimental approach is used for studying the response of ethanol-suspended SnO{sub 2} nanobelts under the influence of low frequency ac electric fields. The electrically generated forces are estimated by analyzing the angular motion of the nanobelt, induced by repulsive forces originating predominantly from negative dielectrophoresis (DEP) on planar microelectrodes. The nanobelt motion is experimentally recorded in real time in the low frequency range (<100 kHz) and the angular velocities are calculated. A simple analytical model of force balance between the electrical forces and fluidic drag for long nano-objects is developed and used to deduce estimates of the frequency-dependent DEP force and torque magnitudes from the angular velocity data. Additional experiments, performed in a parallel plate electrode configuration in a fluidic channel to investigate the effect of dc and very low frequency ac ({approx}Hz) electric fields, indicate the presence of electrophoresis in the ethanol-suspended SnO{sub 2} nanobelts. The experimentally observed nanobelt motion is analyzed using the equation of motion, and an order-of-magnitude estimate of the nanobelt surface charge density is obtained.

  6. Morphology–dependent electrochemical sensing properties of manganese dioxide–graphene oxide hybrid for guaiacol and vanillin

    International Nuclear Information System (INIS)

    Highlights: • MnO2 with different morphologies were prepared via facile methods. • MnO2 are loaded on GO via simply grinding which have high solubility and stability. • MnO2–GO exhibit high electrocatalytic activities depending on their shapes. • MnO2–GO is first used to the determination of guaiacol and vanillin simultaneously. - Abstract: Various morphologies of manganese dioxide (MnO2) electrocatalysts, including nanoflowers, nanorods, nanotubes, nanoplates, nanowires and microspheres were prepared via facile hydrothermal synthesis and precipitation methods. By simply grinding with graphene oxide (GO), MnO2 could be readily dissolved in water with high solubility and stability. The structures and electrochemical performances of these as–prepared MnO2–GO hybrids were fully characterized by various techniques, and the properties were found to be strongly dependent on morphology. As sensing materials for the simultaneous determination of guaiacol and vanillin for the first time, the nanoflowers–like MnO2, coupled with GO, exhibited relatively high sensitivity. The enhanced electrocatalytic activity was ascribed to the high purity, good crystallinity, and unique porous microstructure, which were favorable for transfer of electrons. These results may provide valuable insights for the development of nanostructured modified electrodes for next–generation high–performance electrochemical sensors

  7. Channel length dependence of negative-bias-illumination-stress in amorphous-indium-gallium-zinc-oxide thin-film transistors

    International Nuclear Information System (INIS)

    We have investigated the dependence of Negative-Bias-illumination-Stress (NBIS) upon channel length, in amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The negative shift of the transfer characteristic associated with NBIS decreases for increasing channel length and is practically suppressed in devices with L = 100-μm. The effect is consistent with creation of donor defects, mainly in the channel regions adjacent to source and drain contacts. Excellent agreement with experiment has been obtained by an analytical treatment, approximating the distribution of donors in the active layer by a double exponential with characteristic length LD ∼ Ln ∼ 10-μm, the latter being the electron diffusion length. The model also shows that a device with a non-uniform doping distribution along the active layer is in all equivalent, at low drain voltages, to a device with the same doping averaged over the active layer length. These results highlight a new aspect of the NBIS mechanism, that is, the dependence of the effect upon the relative magnitude of photogenerated holes and electrons, which is controlled by the device potential/band profile. They may also provide the basis for device design solutions to minimize NBIS

  8. Cellular mechanisms for the treatment of chronic heart failure: the nitric oxide- and adenosine-dependent pathways.

    Science.gov (United States)

    Minamino, Tetsuo; Kitakaze, Masafumi

    2002-05-01

    Accumulated evidence suggests that several drugs proven to improve survival in patients with chronic heart failure (CHF) enhance endogenous nitric oxide (NO)- and/or adenosine-dependent pathways. Indeed, we and others have demonstrated that: i) antagonists of either renin-angiotensin-aldosterone or beta-adrenergic systems enhance NO-dependent pathways; ii) although carvedilol and amlodipine belong to different drug classes, both of them can increase cardiac adenosine levels; iii) increased adenosine levels by dipyridamole are associated with the improvement of CHF. Interestingly, both NO and adenosine have multifactorial beneficial actions in cardiovascular systems. First of all, both of them induce vasodilation and decrease myocardial hypercontractility, which may contribute to a reduction in the severity of myocardial ischaemia. Both adenosine and NO are also involved in cardioprotection attributable to acute and late phases of ischaemic preconditioning, respectively. Secondly, they can modulate the neurohormonal systems that contribute to the progression of CHF. Thus, we propose that enhancement of endogenous NO and/or adenosine as potential therapeutic targets in a new strategy for the treatment for CHF. PMID:15989539

  9. Channel length dependence of negative-bias-illumination-stress in amorphous-indium-gallium-zinc-oxide thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Um, Jae Gwang; Mativenga, Mallory; Jang, Jin, E-mail: jjang@khu.ac.kr [Advanced Display Research Center, Department of Information Display, Kyung Hee University, Dongdaemun-gu, Seoul 130-701 (Korea, Republic of); Migliorato, Piero [Advanced Display Research Center, Department of Information Display, Kyung Hee University, Dongdaemun-gu, Seoul 130-701 (Korea, Republic of); Electrical Engineering Division, Department of Engineering, Cambridge University, Cambridge CB3 0FA (United Kingdom)

    2015-06-21

    We have investigated the dependence of Negative-Bias-illumination-Stress (NBIS) upon channel length, in amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The negative shift of the transfer characteristic associated with NBIS decreases for increasing channel length and is practically suppressed in devices with L = 100-μm. The effect is consistent with creation of donor defects, mainly in the channel regions adjacent to source and drain contacts. Excellent agreement with experiment has been obtained by an analytical treatment, approximating the distribution of donors in the active layer by a double exponential with characteristic length L{sub D} ∼ L{sub n} ∼ 10-μm, the latter being the electron diffusion length. The model also shows that a device with a non-uniform doping distribution along the active layer is in all equivalent, at low drain voltages, to a device with the same doping averaged over the active layer length. These results highlight a new aspect of the NBIS mechanism, that is, the dependence of the effect upon the relative magnitude of photogenerated holes and electrons, which is controlled by the device potential/band profile. They may also provide the basis for device design solutions to minimize NBIS.

  10. Mechanism for excitation-dependent photoluminescence from graphene quantum dots and other graphene oxide derivates: consensus, debates and challenges

    Science.gov (United States)

    Gan, Zhixing; Xu, Hao; Hao, Yanling

    2016-04-01

    Luminescent nanomaterials, with wide applications in biosensing, bioimaging, illumination and display techniques, have been consistently garnering enormous research attention. In particular, those with wavelength-controllable emissions could be highly beneficial. Carbon nanostructures, including graphene quantum dots (GQDs) and other graphene oxide derivates (GODs), with excitation-dependent photoluminescence (PL), which means their fluorescence color could be tuned simply by changing the excitation wavelength, have attracted lots of interest. However the intrinsic mechanism for the excitation-dependent PL is still obscure and fiercely debated presently. In this review, we attempt to summarize the latest efforts to explore the mechanism, including the quantum confinement effect, surface traps model, giant red-edge effect, edge states model and electronegativity of heteroatom model, as well as the newly developed synergistic model, to seek some clues to unravel the mechanism. Meanwhile the controversial difficulties for each model are further discussed. Besides this, the challenges and potential influences of the synthetic methodology and development of the materials are illustrated extensively to elicit more thought and constructive attempts toward their application.

  11. A higher oxidative status accelerates senescence and aggravates age-dependent disorders in SAMP strains of mice.

    Science.gov (United States)

    Hosokawa, Masanori

    2002-11-01

    The SAM strain of mice is actually a group of related inbred strains consisting of series of SAMP (accelerated senescence-prone, short-lived) and SAMR (accelerated senescence-resistant, longer-lived) strains. Comparing with the SAMR strains, the SAMP strains of mice show a more accelerated senescence process, shorter lifespan, and an earlier onset and more rapid progress of age-associated pathological phenotypes similar to several geriatric disorders observed in humans, including senile osteoporosis, degenerative joint disease, age-related deficits in learning and memory, olfactory bulb and forebrain atrophy, presbycusis and retinal atrophy, senile amyloidosis, immunosenescence, senile lungs, and diffuse medial thickening of the aorta. The higher oxidative stress observed in the SAMP strains of mice are partly caused by mitochondrial dysfunction, and may be one cause of the senescence acceleration and age-dependent alterations in cell structure and function, including neuronal cell degeneration. This senescence acceleration is also observed during senescence/crisis in cultures of isolated fibroblast-like cells from SAMP strains of mice, and was associated with a hyperoxidative status. These observations suggest that the SAM strains are useful tools in the attempt to understand the mechanisms of age-dependent degeneration of cells and tissues, and their aggravation, and to develop clinical interventions. PMID:12470893

  12. Mechanism for excitation-dependent photoluminescence from graphene quantum dots and other graphene oxide derivates: consensus, debates and challenges.

    Science.gov (United States)

    Gan, Zhixing; Xu, Hao; Hao, Yanling

    2016-04-14

    Luminescent nanomaterials, with wide applications in biosensing, bioimaging, illumination and display techniques, have been consistently garnering enormous research attention. In particular, those with wavelength-controllable emissions could be highly beneficial. Carbon nanostructures, including graphene quantum dots (GQDs) and other graphene oxide derivates (GODs), with excitation-dependent photoluminescence (PL), which means their fluorescence color could be tuned simply by changing the excitation wavelength, have attracted lots of interest. However the intrinsic mechanism for the excitation-dependent PL is still obscure and fiercely debated presently. In this review, we attempt to summarize the latest efforts to explore the mechanism, including the quantum confinement effect, surface traps model, giant red-edge effect, edge states model and electronegativity of heteroatom model, as well as the newly developed synergistic model, to seek some clues to unravel the mechanism. Meanwhile the controversial difficulties for each model are further discussed. Besides this, the challenges and potential influences of the synthetic methodology and development of the materials are illustrated extensively to elicit more thought and constructive attempts toward their application. PMID:27030656

  13. Potentiostatic Oxide Growth Kinetics on Ni-Cr and Co-Cr Alloys: Potential and pH Dependences

    International Nuclear Information System (INIS)

    Oxide growth kinetics on the Ni-Cr-Fe alloy Inconel 600 and the Co-Cr alloy Stellite 6 under potentiostatic polarization have been investigated by current measurements augmented by ex-situ surface analyses. The results reveal a mechanism for metal oxidation and oxide formation that is common to both alloys. The reaction thermodynamics for the oxidation of a metal determine whether a certain metal oxidation can or cannot occur. However, the metal oxidation proceeds via two competing pathways, oxide formation and metal ion dissolution. At pH 10.6 where the solubilities of FeII, NiII or CoII species are near their minima, oxide formation is favoured over metal ion dissolution. As the oxide grows, the rate of metal oxidation decreases with time due to an increase in the electrochemical potential barrier. The oxide formation occurs sequentially; the conversion of the preformed Cr2O3 film to chromite (FeCr2O4 or CoCr2O4) proceeds before the next layers of Fe3O4/NiFe2O4 and NiO/Ni(OH)2 grow on Inconel 600, or CoO/Co(OH)2 grows on Stellite 6. The effect of a different EAPP is to limit the oxidation sequence. The pH does not directly affect the driving force for metal oxidation but it strongly influences the relative rates of oxide formation and metal dissolution, thereby affecting metal oxidation kinetics

  14. Roles of NIA/NR/NOA1-dependent nitric oxide production and HY1 expression in the modulation of Arabidopsis salt tolerance

    OpenAIRE

    Xie, Yanjie; Mao, Yu; Lai, Diwen; Zhang, Wei; Zheng, Tianqing; Shen, Wenbiao

    2013-01-01

    Despite substantial evidence on the separate roles of Arabidopsis nitric oxide-associated 1 (NOA1)-associated nitric oxide (NO) production and haem oxygenase 1 (HY1) expression in salt tolerance, their integrative signalling pathway remains largely unknown. To fill this knowledge gap, the interaction network among nitrate reductase (NIA/NR)- and NOA1-dependent NO production and HY1 expression was studied at the genetic and molecular levels. Upon salinity stress, the majority of NO production ...

  15. Induction of Nitrate-Dependent Fe(II) Oxidation by Fe(II) in Dechloromonas sp. Strain UWNR4 and Acidovorax sp. Strain 2AN

    OpenAIRE

    Chakraborty, Anirban; Picardal, Flynn

    2013-01-01

    We evaluated the inducibility of nitrate-dependent Fe(II)-EDTA oxidation (NDFO) in non-growth, chloramphenicol-amended, resting-cell suspensions of Dechloromonas sp. strain UWNR4 and Acidovorax sp. strain 2AN. Cells previously incubated with Fe(II)-EDTA oxidized ca. 6-fold more Fe(II)-EDTA than cells previously incubated with Fe(III)-EDTA. This is the first report of induction of NDFO by Fe(II).

  16. Oxidant-NO dependent gene regulation in dogs with type I diabetes: impact on cardiac function and metabolism

    Directory of Open Access Journals (Sweden)

    Ojaimi Caroline

    2010-08-01

    Full Text Available Abstract Background The mechanisms responsible for the cardiovascular mortality in type I diabetes (DM have not been defined completely. We have shown in conscious dogs with DM that: 1 baseline coronary blood flow (CBF was significantly decreased, 2 endothelium-dependent (ACh coronary vasodilation was impaired, and 3 reflex cholinergic NO-dependent coronary vasodilation was selectively depressed. The most likely mechanism responsible for the depressed reflex cholinergic NO-dependent coronary vasodilation was the decreased bioactivity of NO from the vascular endothelium. The goal of this study was to investigate changes in cardiac gene expression in a canine model of alloxan-induced type 1 diabetes. Methods Mongrel dogs were chronically instrumented and the dogs were divided into two groups: one normal and the other diabetic. In the diabetic group, the dogs were injected with alloxan monohydrate (40-60 mg/kg iv over 1 min. The global changes in cardiac gene expression in dogs with alloxan-induced diabetes were studied using Affymetrix Canine Array. Cardiac RNA was extracted from the control and DM (n = 4. Results The array data revealed that 797 genes were differentially expressed (P 2+ cycling genes (ryanodine receptor; SERCA2 Calcium ATPase, structural proteins (actin alpha. Of particular interests are genes involved in glutathione metabolism (glutathione peroxidase 1, glutathione reductase and glutathione S-transferase, which were markedly down regulated. Conclusion our findings suggest that type I diabetes might have a direct effect on the heart by impairing NO bioavailability through oxidative stress and perhaps lipid peroxidases.

  17. Trx2p-dependent regulation of Saccharomyces cerevisiae oxidative stress response by the Skn7p transcription factor under respiring conditions.

    Directory of Open Access Journals (Sweden)

    Rocío Gómez-Pastor

    Full Text Available The whole genome analysis has demonstrated that wine yeasts undergo changes in promoter regions and variations in gene copy number, which make them different to lab strains and help them better adapt to stressful conditions during winemaking, where oxidative stress plays a critical role. Since cytoplasmic thioredoxin II, a small protein with thiol-disulphide oxidoreductase activity, has been seen to perform important functions under biomass propagation conditions of wine yeasts, we studied the involvement of Trx2p in the molecular regulation of the oxidative stress transcriptional response on these strains. In this study, we analyzed the expression levels of several oxidative stress-related genes regulated by either Yap1p or the co-operation between Yap1p and Skn7p. The results revealed a lowered expression for all the tested Skn7p dependent genes in a Trx2p-deficient strain and that Trx2p is essential for the oxidative stress response during respiratory metabolism in wine yeast. Additionally, activity of Yap1p and Skn7p dependent promoters by β-galactosidase assays clearly demonstrated that Skn7p-dependent promoter activation is affected by TRX2 gene deficiency. Finally we showed that deleting the TRX2 gene causes Skn7p hyperphosphorylation under oxidative stress conditions. We propose Trx2p to be a new positive efector in the regulation of the Skn7p transcription factor that controls phosphorylation events and, therefore, modulates the oxidative stress response in yeast.

  18. Immobilized cytochrome c bound to cardiolipin exhibits peculiar oxidation state-dependent axial heme ligation and catalytically reduces dioxygen.

    Science.gov (United States)

    Ranieri, Antonio; Millo, Diego; Di Rocco, Giulia; Battistuzzi, Gianantonio; Bortolotti, Carlo A; Borsari, Marco; Sola, Marco

    2015-04-01

    Mitochondrial cytochrome c (cytc) plays an important role in programmed cell death upon binding to cardiolipin (CL), a negatively charged phospholipid of the inner mitochondrial membrane (IMM). Although this binding has been thoroughly investigated in solution, little is known on the nature and reactivity of the adduct (cytc-CL) immobilized at IMM. In this work, we have studied electrochemically cytc-CL immobilized on a hydrophobic self-assembled monolayer (SAM) of decane-1-thiol. This construct would reproduce the motional restriction and the nonpolar environment experienced by cytc-CL at IMM. Surface-enhanced resonance Raman (SERR) studies allowed the axial heme iron ligands to be identified, which were found to be oxidation state dependent and differ from those of cytc-CL in solution. In particular, immobilized cytc-CL experiences an equilibrium between a low-spin (LS) 6c His/His and a high-spin (HS) 5c His/- coordination states. The former prevails in the oxidized and the latter in the reduced form. Axial coordination of the ferric heme thus differs from the (LS) 6c His/Lys and (LS) 6c His/OH(-) states observed in solution. Moreover, a relevant finding is that the immobilized ferrous cytc-CL is able to catalytically reduce dioxygen, likely to superoxide ion. These findings indicate that restriction of motional freedom due to interaction with the membrane is an additional factor playing in the mechanism of cytc unfolding and cytc-mediated peroxidation functional to the apoptosis cascade. PMID:25627142

  19. The Trypanosoma cruzi vitamin C dependent peroxidase confers protection against oxidative stress but is not a determinant of virulence.

    Directory of Open Access Journals (Sweden)

    Martin C Taylor

    2015-04-01

    Full Text Available The neglected parasitic infection Chagas disease is rapidly becoming a globalised public health issue due to migration. There are only two anti-parasitic drugs available to treat this disease, benznidazole and nifurtimox. Thus it is important to identify and validate new drug targets in Trypanosoma cruzi, the causative agent. T. cruzi expresses an ER-localised ascorbate-dependent peroxidase (TcAPx. This parasite-specific enzyme has attracted interest from the perspective of targeted chemotherapy.To assess the importance of TcAPx in protecting T. cruzi from oxidative stress and to determine if it is essential for virulence, we generated null mutants by targeted gene disruption. Loss of activity was associated with increased sensitivity to exogenous hydrogen peroxide, but had no effect on susceptibility to the front-line Chagas disease drug benznidazole. This suggests that increased oxidative stress in the ER does not play a significant role in its mechanism of action. Homozygous knockouts could proceed through the entire life-cycle in vitro, although they exhibited a significant decrease in their ability to infect mammalian cells. To investigate virulence, we exploited a highly sensitive bioluminescence imaging system which allows parasites to be monitored in real-time in the chronic stage of murine infections. This showed that depletion of enzyme activity had no effect on T. cruzi replication, dissemination or tissue tropism in vivo.TcAPx is not essential for parasite viability within the mammalian host, does not have a significant role in establishment or maintenance of chronic infections, and should therefore not be considered a priority for drug design.

  20. Co-occurrence of nitrite-dependent anaerobic ammonium and methane oxidation processes in subtropical acidic forest soils.

    Science.gov (United States)

    Meng, Han; Wang, Yong-Feng; Chan, Ho-Wang; Wu, Ruo-Nan; Gu, Ji-Dong

    2016-09-01

    Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two new processes of recent discoveries linking the microbial nitrogen and carbon cycles. In this study, 16S ribosomal RNA (rRNA) gene of anammox bacteria and pmoA gene of n-damo bacteria were used to investigate their distribution and diversity in natural acidic and re-vegetated forest soils. The 16S rRNA gene sequences retrieved featured at least three species in two genera known anammox bacteria, namely Candidatus Brocadia anammoxidans, Candidatus Brocadia fulgida, and Candidatus Kuenenia stuttgartiensis while the pmoA gene amplified was affiliated with two species of known n-damo bacteria Candidatus Methylomirabilis oxyfera and a newly established Candidatus Methylomirabilis sp. According to the results, the diversity of anammox bacteria in natural forests was lower than in re-vegetated forests, but no significant difference was observed in n-damo community between them. Quantitative real-time PCR showed that both anammox and n-damo bacteria were more abundant in the lower layer (10-20 cm) than the surface layer (0-5 cm). The abundance of anammox bacteria varied from 2.21 × 10(5) to 3.90 × 10(6) gene copies per gram dry soil, and n-damo bacteria quantities were between 1.69 × 10(5) and 5.07 × 10(6) gene copies per gram dry soil in the two different layers. Both anammox and n-damo bacteria are reported for the first time to co-occur in acidic forest soil in this study, providing a more comprehensive information on more defined microbial processes contributing to C and N cycles in the ecosystems. PMID:27178181

  1. Carbonate effects and pH-dependence of uranium sorption onto bacteriogenic iron oxides: Kinetic and equilibrium studies

    International Nuclear Information System (INIS)

    The removal of U(VI) from groundwaters by adsorption onto bacteriogenic iron oxides (BIOS) has been investigated under batch mode. The adsorbent dosage, the uranium concentration, the concentration of carbonate and the use of a real groundwater spiked with uranium comprised the examined parameters. In addition, the effect of pH was examined in two different water matrixes, i.e., in distilled water and in real groundwater. Equilibrium studies were carried out to determine the maximum adsorption capacity of BIOS and the data correlated well with the Langmuir and Freundlich models. The presence of carbonate affected adversely the adsorption of U(VI) onto BIOS. The maximum adsorption capacity of BIOS was 9.25 mg g-1 at 0.1 mM carbonate concentration and decreased to 6.93 mg g-1 at 0.5 mM carbonate concentration, whereas at carbonate concentration of 2 mM practically no adsorption occurred. The data were further analyzed using the pseudo-second order kinetic equation, which fitted best the experimental results. The initial adsorption rate (h) was found to increase with decreasing the concentration of carbonate in all cases. When experiments were accomplished in the absence of carbonate, the pH values did not have an effect on the adsorption of U(VI). However, the extent of U(VI) adsorption was strongly pH-dependent when the experiments were carried out in the real groundwater. The maximum adsorption capacity increased sharply as the pH decreased and optimum removal was obtained in the pH range 3.2-4.0, thus bacteriogenic iron oxides can found application in the removal of U(VI) by adsorption from low pH or low carbonate waters

  2. The effect of anandamide on uterine nitric oxide synthase activity depends on the presence of the blastocyst.

    Directory of Open Access Journals (Sweden)

    Micaela S Sordelli

    Full Text Available Nitric oxide production, catalyzed by nitric oxide synthase (NOS, should be strictly regulated to allow embryo implantation. Thus, our first aim was to study NOS activity during peri-implantation in the rat uterus. Day 6 inter-implantation sites showed lower NOS activity (0.19±0.01 pmoles L-citrulline mg prot(-1 h(-1 compared to days 4 (0.34±0.03 and 5 (0.35±0.02 of pregnancy and to day 6 implantation sites (0.33±0.01. This regulation was not observed in pseudopregnancy. Both dormant and active blastocysts maintained NOS activity at similar levels. Anandamide (AEA, an endocannabinoid, binds to cannabinoid receptors type 1 (CB1 and type 2 (CB2, and high concentrations are toxic for implantation and embryo development. Previously, we observed that AEA synthesis presents an inverted pattern compared to NOS activity described here. We adopted a pharmacological approach using AEA, URB-597 (a selective inhibitor of fatty acid amide hydrolase, the enzyme that degrades AEA and receptor selective antagonists to investigate the effect of AEA on uterine NOS activity in vitro in rat models of implantation. While AEA (0.70±0.02 vs 0.40±0.04 and URB-597 (1.08±0.09 vs 0.83±0.06 inhibited NOS activity in the absence of a blastocyst (pseudopregnancy through CB2 receptors, AEA did not modulate NOS on day 5 pregnant uterus. Once implantation begins, URB-597 decreased NOS activity on day 6 implantation sites via CB1 receptors (0.25±0.04 vs 0.40±0.05. While a CB1 antagonist augmented NOS activity on day 6 inter-implantation sites (0.17±0.02 vs 0.27±0.02, a CB2 antagonist decreased it (0.17±0.02 vs 0.12±0.01. Finally, we described the expression and localization of cannabinoid receptors during implantation. In conclusion, AEA levels close to and at implantation sites seems to modulate NOS activity and thus nitric oxide production, fundamental for implantation, via cannabinoid receptors. This modulation depends on the presence of the blastocyst. These

  3. Impact of intensive insulin treatment on the development and consequences of oxidative stress in insulin-dependent diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Kocić Radivoj

    2007-01-01

    Full Text Available Background/Aim. The aim of this study, which included patients with insulin-dependent diabetes mellitus, was to determine the influence of the application of various treatment modalities (intensive or conventional on the total plasma antioxidative capacity and lipid peroxidation intensity expressed as malondialdehyde (MDA level, catalase and xanthine oxidase activity, erythrocyte glutatione reduced concentration (GSH RBC, erythrocyte MDA level (MDA RBC, as well as susceptibility of erythrocyte to H2O2-induced oxidative stress. Methods. This study included 42 patients with insulin-dependent diabetes mellitus. In 24 of the patients intensive insulin treatment was applied using the model of short-acting insulin in each meal and medium- acting insulin before going to bed, while in 18 of the patients conventional insulin treatment was applied in two (morning and evening doses. In the examined patients no presence of diabetes mellitus complications was recorded. The control group included 20 healthy adults out of a blood doner group. The plasma and erythrocytes taken from the blood samples were analyzed immediately. Results. This investigation proved that the application of intensive insulin treatment regime significantly improves total antioxidative plasma capacity as compared to the application of conventional therapy regime. The obtained results showed that the both plasma and lipoproteines apo B MDA increased significantly more in the patients on conventional therapy than in the patients on intensive insulin therapy, most probably due to intensified xanthine oxidase activity. The level of the MDA in fresh erythrocytes did not differ significantly between the groups on intensive and conventional therapy. The level of GSH and catalase activity, however, were significantly reduced in the patients on conventional therapy due to the increased susceptibility to H2O2-induced oxidative stress . Conclusion. The presented study confirmed positive effect of

  4. Characterization of pH dependent Mn(II) oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

    Science.gov (United States)

    Bohu, Tsing; Santelli, Cara M; Akob, Denise M.; Neu, Thomas R; Ciobota, Valerian; Rösch, Petra; Popp, Jürgen; Nietzsche, Sándor; Küsel, Kirsten

    2015-01-01

    Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II) at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS), particularly superoxide, appeared to be more important for T-G1 mediated Mn(II) oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II) oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II) oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling.

  5. Characterization of pH dependent Mn(II oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

    Directory of Open Access Journals (Sweden)

    Tsing eBohu

    2015-07-01

    Full Text Available Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB isolates limits our understanding of how pH influences biological Mn(II oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction (XRD, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase (MCO expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS, particularly superoxide, appeared to be more important for T-G1 mediated Mn(II oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling.

  6. Characterization of pH dependent Mn(II) oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

    Science.gov (United States)

    Bohu, Tsing; Santelli, Cara M.; Akob, Denise M.; Neu, Thomas R.; Ciobota, Valerian; Rösch, Petra; Popp, Jürgen; Nietzsche, Sándor; Küsel, Kirsten

    2015-01-01

    Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II) at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS), particularly superoxide, appeared to be more important for T-G1 mediated Mn(II) oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II) oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II) oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling. PMID:26236307

  7. Melatonin membrane receptor (MT1R) expression and nitro-oxidative stress in testis of golden hamster, Mesocricetus auratus: An age-dependent study.

    Science.gov (United States)

    Mukherjee, Arun; Haldar, Chandana

    2015-09-01

    Age-dependent decline in melatonin level induces nitro-oxidative stress that compromises physiological homeostasis including reproduction. However, less information exist regarding the age-dependent variation in local melatonin (lMel) concentration and MT1R expression in testis and its interaction with testicular steroidogenesis and nitro-oxidative stress in golden hamster, Mesocricetus auratus. Therefore, we evaluated lMel level along with MT1R expression and its possible interaction with steroidogenesis and nitro-oxidative stress in testes of young (6weeks), adult (15weeks) and old (2years) aged hamsters. Further, we injected the old hamsters with melatonin to address whether age-related decline in lMel and MT1R is responsible for the reduction in testicular steroidogenesis and antioxidant status. Increased expression of steroidogenic markers suggests increased testicular steroidogenesis in adult hamsters that declined in old hamsters. An age-dependent elevation in the level of NOX, TBARS, corticosterone and the expression of iNOS and GR with a concomitant decrease in enzyme activities for SOD, CAT, GSH-PX indicate increased nitro-oxidative stress in testes. Data suggest that reproductive senescence in male hamsters might be a consequence of declined lMel concentration with MT1R expression inducing nitro-oxidative stress resulting in diminished testicular steroidogenesis. However, administration of Mel in old-aged hamsters significantly increased steroidogenesis and antioxidant status without a significant variation in lMel concentration and MT1R expression in testes. Therefore, decreased lMel and MT1R might not be the causative factor underlying the age-associated decrease in antioxidant defence and steroidogenesis in testes. In conclusion, Mel induced amelioration of testicular oxidative insult and elevation of steroidogenic activity suggests a potential role of increased nitro-oxidative stress underlying the age-dependent decrease in steroidogenesis. PMID

  8. Pathophysiological concentrations of glucose promote oxidative modification of low density lipoprotein by a superoxide-dependent pathway.

    OpenAIRE

    Kawamura, M.; Heinecke, J W; Chait, A.

    1994-01-01

    Oxidized lipoproteins may be important in the pathogenesis of atherosclerosis. Because diabetic subjects are particularly prone to vascular disease, and glucose autoxidation and protein glycation generate reactive oxygen species, we explored the role of glucose in lipoprotein oxidation. Glucose enhanced low density lipoprotein (LDL) oxidation at concentrations seen in the diabetic state. Conjugated dienes, thiobarbituric acid reactive substances, electrophoretic mobility, and degradation by m...

  9. Field Dependence of the Spin Relaxation Within a Film of Iron Oxide Nanocrystals Formed via Electrophoretic Deposition

    Directory of Open Access Journals (Sweden)

    Hasan SA

    2010-01-01

    Full Text Available Abstract The thermal relaxation of macrospins in a strongly interacting thin film of spinel-phase iron oxide nanocrystals (NCs is probed by vibrating sample magnetometry (VSM. Thin films are fabricated by depositing FeO/Fe3O4 core–shell NCs by electrophoretic deposition (EPD, followed by sintering at 400°C. Sintering transforms the core–shell structure to a uniform spinel phase, which effectively increases the magnetic moment per NC. Atomic force microscopy (AFM confirms a large packing density and a reduced inter-particle separation in comparison with colloidal assemblies. At an applied field of 25 Oe, the superparamagnetic blocking temperature is TBSP ≈ 348 K, which is much larger than the Néel-Brown approximation of TBSP ≈ 210 K. The enhanced value of TBSP is attributed to strong dipole–dipole interactions and local exchange coupling between NCs. The field dependence of the blocking temperature, TBSP(H, is characterized by a monotonically decreasing function, which is in agreement with recent theoretical models of interacting macrospins.

  10. Nitric oxide decreases the sensitivity of pulmonary endothelial cells to LPS-induced apoptosis in a zinc-dependent fashion.

    Science.gov (United States)

    Tang, Zi-Lue; Wasserloos, Karla J; Liu, Xianghong; Stitt, Molly S; Reynolds, Ian J; Pitt, Bruce R; St Croix, Claudette M

    2002-01-01

    We hypothesized that: (a) S-nitrosylation of metallothionein (MT) is a component of pulmonary endothelial cell nitric oxide (NO) signaling that is associated with an increase in labile zinc; and (b) NO mediated increases in labile zinc in turn reduce the sensitivity of pulmonary endothelium to LPS-induced apoptosis. We used microspectrofluorometric techniques to show that exposing mouse lung endothelial cells (MLEC) to the NO-donor, S-nitrosocysteine, resulted in a 45% increase in fluorescence of the Zn2+-specific fluorophore, Zinquin, that was rapidly reversed by exposure to the Zn2+ chelator, NNN'N'-tetrakis-(2-pyridylmethyl)ethylenediamine; TPEN). The absence of a NO-mediated increase in labile Zn2+ in MLEC from MT-I and -II knockout mice inferred a critical role for MT in the regulation of Zn2+ homeostasis by NO. Furthermore, we found that prior exposure of cultured endothelial cells from sheep pulmonary artery (SPAEC), to the NO-donor, S-nitroso-N-acetylpenicillamine (SNAP) reduced their sensitivity to lipopolysaccharide (LPS) induced apoptosis. The anti-apoptotic effects of NO were significantly inhibited by Zn2+ chelation with low doses of TPEN (10 microM). Collectively, these data suggest that S-nitrosylation of MT is associated with an increase in labile (TPEN chelatable) zinc and NO-mediated MT dependent zinc release is associated with reduced sensitivity to LPS-induced apoptosis in pulmonary endothelium. PMID:12162436

  11. Ribosome-dependent ATPase interacts with conserved membrane protein in Escherichia coli to modulate protein synthesis and oxidative phosphorylation.

    Directory of Open Access Journals (Sweden)

    Mohan Babu

    Full Text Available Elongation factor RbbA is required for ATP-dependent deacyl-tRNA release presumably after each peptide bond formation; however, there is no information about the cellular role. Proteomic analysis in Escherichia coli revealed that RbbA reciprocally co-purified with a conserved inner membrane protein of unknown function, YhjD. Both proteins are also physically associated with the 30S ribosome and with members of the lipopolysaccharide transport machinery. Genome-wide genetic screens of rbbA and yhjD deletion mutants revealed aggravating genetic interactions with mutants deficient in the electron transport chain. Cells lacking both rbbA and yhjD exhibited reduced cell division, respiration and global protein synthesis as well as increased sensitivity to antibiotics targeting the ETC and the accuracy of protein synthesis. Our results suggest that RbbA appears to function together with YhjD as part of a regulatory network that impacts bacterial oxidative phosphorylation and translation efficiency.

  12. Dependence of gamma-aminobutyric acid modulation of cholinergic transmission on nitric oxide and purines in cat terminal ileum.

    Science.gov (United States)

    Pencheva, N

    1997-11-27

    The possible involvement of purines and/or nitric oxide (NO) in the gamma-aminobutyric acid (GABA)A receptor-mediated effects on the spontaneous activity of isolated preparations from longitudinal and circular muscles of cat terminal ileum was investigated. GABA had biphasic effects, which were neurogenic and muscarinic. ATP and adenosine dose dependently inhibited the activity of the muscles. A contractile response evoked by the nucleotide only was also observed. The effects of the purines were equipotent and resistant to Nomega-nitro-L-arginine (L-NNA), tetrodotoxin and to desensitization by alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-meATP), except for the contractile effect of ATP, which was abolished by alpha,beta-meATP. Pretreatment of the preparations with ATP or adenosine produced: (i) desensitization to the effects of the respective purinoceptor agonist only; and (ii) suppression of the GABA-induced responses of longitudinal and circular muscles. Hemoglobin and L-NNA greatly reduced or completely blocked the GABA(A)-induced relaxation and decreased the GABA(A)-induced contraction. Our results indicate that purines and NO, to a different extent, mediate the relaxant phase of the GABA effects in both layers. Interactions between muscarinic cholinoceptors and GABA-nitrergic pathway and a concomitant activation of postjunctional P1 and P2y purinoceptors are suggested to explain the prejunctional biphasic effects of GABA. PMID:9473135

  13. Nitrate-dependent anaerobic ferrous oxidation (NAFO) by denitrifying bacteria: a perspective autotrophic nitrogen pollution control technology.

    Science.gov (United States)

    Zhang, Meng; Zheng, Ping; Wang, Ru; Li, Wei; Lu, Huifeng; Zhang, Jiqiang

    2014-12-01

    The nitrate-dependent anaerobic ferrous oxidation (NAFO) is an important discovery in the fields of microbiology and geology, which is a valuable biological reaction since it can convert nitrate into nitrogen gas, removing nitrogen from wastewater. The research on NAFO can promote the development of novel autotrophic biotechnologies for nitrogen pollution control and get a deep insight into the biogeochemical cycles. In this work, batch experiments were conducted with denitrifying bacteria as biocatalyst to investigate the performance of nitrogen removal by NAFO. The results showed that the denitrifying bacteria were capable of chemolithotrophic denitrification with ferrous salt as electron donor, namely NAFO. And the maximum nitrate conversion rates (qmax) reached 57.89 mg (g VSS d)−1, which was the rate-limiting step in NAFO. Fe/N ratio, temperature and initial pH had significant influences on nitrogen removal by NAFO process, and their optimal values were 2.0 °C, 30.15 °C and 8.0 °C, respectively. PMID:25461924

  14. Performance of nitrate-dependent anaerobic ferrous oxidizing (NAFO) process: a novel prospective technology for autotrophic denitrification.

    Science.gov (United States)

    Zhang, Meng; Zheng, Ping; Li, Wei; Wang, Ru; Ding, Shuang; Abbas, Ghulam

    2015-03-01

    Nitrate-dependent anaerobic ferrous oxidizing (NAFO) is a valuable biological process, which utilizes ferrous iron to convert nitrate into nitrogen gas, removing nitrogen from wastewater. In this work, the performance of NAFO process was investigated as a nitrate removal technology. The results showed that NAFO system was feasible for autotrophic denitrification. The volumetric loading rate (VLR) and volumetric removal rate (VRR) under steady state were 0.159±0.01 kg-N/(m(3) d) and 0.073±0.01 kg-N/(m(3) d), respectively. In NAFO system, the effluent pH was suggested as an indicator which demonstrated a good correlation with nitrogen removal. The nitrate concentration was preferred to be less than 130 mg-N/L. Organic matters had little influence on NAFO performance. Abundant iron compounds were revealed to accumulate in NAFO sludge with peak value of 51.73% (wt), and they could be recycled for phosphorus removal, with capacity of 16.57 mg-P/g VS and removal rate of 94.77±2.97%, respectively. PMID:25576990

  15. Leptin Inhibits the Proliferation of Vascular Smooth Muscle Cells Induced by Angiotensin II through Nitric Oxide-Dependent Mechanisms

    Directory of Open Access Journals (Sweden)

    Amaia Rodríguez

    2010-01-01

    Full Text Available Objective. This study was designed to investigate whether leptin modifies angiotensin (Ang II-induced proliferation of aortic vascular smooth muscle cells (VSMCs from 10-week-old male Wistar and spontaneously hypertensive rats (SHR, and the possible role of nitric oxide (NO. Methods. NO and NO synthase (NOS activity were assessed by the Griess and 3H-arginine/citrulline conversion assays, respectively. Inducible NOS (iNOS and NADPH oxidase subutnit Nox2 expression was determined by Western-blot. The proliferative responses to Ang II were evaluated through enzymatic methods. Results. Leptin inhibited the Ang II-induced proliferative response of VSMCs from control rats. This inhibitory effect of leptin was abolished by NOS inhibitor, NMMA, and iNOS selective inhibitor, L-NIL, and was not observed in leptin receptor-deficient fa/fa rats. SHR showed increased serum leptin concentrations and lipid peroxidation. Despite a similar leptin-induced iNOS up-regulation, VSMCs from SHR showed an impaired NOS activity and NO production induced by leptin, and an increased basal Nox2 expression. The inhibitory effect of leptin on Ang II-induced VSMC proliferation was attenuated. Conclusion. Leptin blocks the proliferative response to Ang II through NO-dependent mechanisms. The attenuation of this inhibitory effect of leptin in spontaneous hypertension appears to be due to a reduced NO bioavailability in VSMCs.

  16. Temperature dependent electron effective mass and barrier height in HfO2 based metal/oxide/metal devices

    Science.gov (United States)

    El Kamel, F.

    2015-07-01

    Electrical measurements are realized on Cu/HfO2/Pt capacitors to extract the electron effective mass in HfO2 and the barrier height at the Cu/HfO2 interface. The dominant conduction mechanisms are found to be the Schottky emission at medium voltages and the Fowler-Nordheim tunneling at high voltages. Previous research has usually been carried out by assuming a constant value for either the electron effective mass in oxide or the interfacial potential barrier height to determine the other parameter. However, in contrast to that general practice, an iterative method was proposed in the present study to determine, at the same time, the electron effective mass in HfO2 and the barrier height at the Cu/HfO2 interface without making any prior assumption about their values. The temperature dependence of these two parameters was also studied in the 298-423 K range. It is found that they strongly vary with temperature. The effective mass decreases quadratically with temperature, while the barrier height increases linearly with temperature.

  17. A Method to Site-Specifically Identify and Quantitate Carbonyl End Products of Protein Oxidation Using Oxidation-Dependent Element Coded Affinity Tags (O-ECAT) and NanoLiquid Chromatography Fourier Transform Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S; Young, N L; Whetstone, P A; Cheal, S M; Benner, W H; Lebrilla, C B; Meares, C F

    2005-08-25

    Protein oxidation is linked to cellular stress, aging, and disease. Protein oxidations that result in reactive species are of particular interest, since these reactive oxidation products may react with other proteins or biomolecules in an unmediated and irreversible fashion, providing a potential marker for a variety of disease mechanisms. We have developed a novel system to identify and quantitate, relative to other states, the sites of oxidation on a given protein. A specially designed Oxidation-dependent carbonyl-specific Element-Coded Affinity Mass Tag (O-ECAT), AOD, ((S)-2-(4-(2-aminooxy)-acetamido)-benzyl)-1, 4, 7, 10-tetraazacyclododecane-N, N', N'', N'''-tetraacetic acid, is used to covalently tag the residues of a protein oxidized to aldehyde or keto end products. After proteolysis, the resulting AOD-tagged peptides are affinity purified, and analyzed by nanoLC-FTICR-MS, which provides high specificity in extracting co-eluting AOD mass pairs with a unique mass difference and affords relative quantitation based on isotopic ratios. Using this methodology, we have mapped the surface oxidation sites on a model protein, recombinant human serum albumin (rHSA) in its native form (as purchased) and after FeEDTA oxidation. A variety of modified amino acid residues including lysine, arginine, proline, histidine, threonine, aspartic and glutamic acids, were found to be oxidized to aldehyde and keto end products. The sensitivity of this methodology is shown by the number of peptides identified, twenty peptides on the native protein and twenty-nine after surface oxidation using FeEDTA and ascorbate. All identified peptides map to the surface of the HSA crystal structure validating this method for identifying oxidized amino acids on protein surfaces. In relative quantitation experiments between FeEDTA oxidation and native protein oxidation, identified sites showed different relative propensities towards oxidation independent of amino acid

  18. MAPK pathway activation by chronic lead-exposure increases vascular reactivity through oxidative stress/cyclooxygenase-2-dependent pathways

    Energy Technology Data Exchange (ETDEWEB)

    Simões, Maylla Ronacher, E-mail: yllars@hotmail.com [Dept. of Physiological Sciences, Federal University of Espirito Santo, Vitória, ES CEP 29040-091 (Brazil); Department of Pharmacology, Universidad Autonoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid (Spain); Aguado, Andrea [Department of Pharmacology, Universidad Autonoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid (Spain); Fiorim, Jonaína; Silveira, Edna Aparecida; Azevedo, Bruna Fernandes; Toscano, Cindy Medice [Dept. of Physiological Sciences, Federal University of Espirito Santo, Vitória, ES CEP 29040-091 (Brazil); Zhenyukh, Olha; Briones, Ana María [Department of Pharmacology, Universidad Autonoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid (Spain); Alonso, María Jesús [Dept. of Biochemistry, Physiology and Molecular Genetics, Universidad Rey Juan Carlos, Alcorcón (Spain); Vassallo, Dalton Valentim [Dept. of Physiological Sciences, Federal University of Espirito Santo, Vitória, ES CEP 29040-091 (Brazil); Health Science Center of Vitória-EMESCAM, Vitória, ES CEP 29045-402 (Brazil); Salaices, Mercedes, E-mail: mercedes.salaices@uam.es [Department of Pharmacology, Universidad Autonoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid (Spain)

    2015-03-01

    Chronic exposure to low lead concentration produces hypertension; however, the underlying mechanisms remain unclear. We analyzed the role of oxidative stress, cyclooxygenase-2-dependent pathways and MAPK in the vascular alterations induced by chronic lead exposure. Aortas from lead-treated Wistar rats (1st dose: 10 μg/100 g; subsequent doses: 0.125 μg/100 g, intramuscular, 30 days) and cultured aortic vascular smooth muscle cells (VSMCs) from Sprague Dawley rats stimulated with lead (20 μg/dL) were used. Lead blood levels of treated rats attained 21.7 ± 2.38 μg/dL. Lead exposure increased systolic blood pressure and aortic ring contractile response to phenylephrine, reduced acetylcholine-induced relaxation and did not affect sodium nitroprusside relaxation. Endothelium removal and L-NAME left-shifted the response to phenylephrine more in untreated than in lead-treated rats. Apocynin and indomethacin decreased more the response to phenylephrine in treated than in untreated rats. Aortic protein expression of gp91(phox), Cu/Zn-SOD, Mn-SOD and COX-2 increased after lead exposure. In cultured VSMCs lead 1) increased superoxide anion production, NADPH oxidase activity and gene and/or protein levels of NOX-1, NOX-4, Mn-SOD, EC-SOD and COX-2 and 2) activated ERK1/2 and p38 MAPK. Both antioxidants and COX-2 inhibitors normalized superoxide anion production, NADPH oxidase activity and mRNA levels of NOX-1, NOX-4 and COX-2. Blockade of the ERK1/2 and p38 signaling pathways abolished lead-induced NOX-1, NOX-4 and COX-2 expression. Results show that lead activation of the MAPK signaling pathways activates inflammatory proteins such as NADPH oxidase and COX-2, suggesting a reciprocal interplay and contribution to vascular dysfunction as an underlying mechanisms for lead-induced hypertension. - Highlights: • Lead-exposure increases oxidative stress, COX-2 expression and vascular reactivity. • Lead exposure activates MAPK signaling pathway. • ROS and COX-2 activation by

  19. MAPK pathway activation by chronic lead-exposure increases vascular reactivity through oxidative stress/cyclooxygenase-2-dependent pathways

    International Nuclear Information System (INIS)

    Chronic exposure to low lead concentration produces hypertension; however, the underlying mechanisms remain unclear. We analyzed the role of oxidative stress, cyclooxygenase-2-dependent pathways and MAPK in the vascular alterations induced by chronic lead exposure. Aortas from lead-treated Wistar rats (1st dose: 10 μg/100 g; subsequent doses: 0.125 μg/100 g, intramuscular, 30 days) and cultured aortic vascular smooth muscle cells (VSMCs) from Sprague Dawley rats stimulated with lead (20 μg/dL) were used. Lead blood levels of treated rats attained 21.7 ± 2.38 μg/dL. Lead exposure increased systolic blood pressure and aortic ring contractile response to phenylephrine, reduced acetylcholine-induced relaxation and did not affect sodium nitroprusside relaxation. Endothelium removal and L-NAME left-shifted the response to phenylephrine more in untreated than in lead-treated rats. Apocynin and indomethacin decreased more the response to phenylephrine in treated than in untreated rats. Aortic protein expression of gp91(phox), Cu/Zn-SOD, Mn-SOD and COX-2 increased after lead exposure. In cultured VSMCs lead 1) increased superoxide anion production, NADPH oxidase activity and gene and/or protein levels of NOX-1, NOX-4, Mn-SOD, EC-SOD and COX-2 and 2) activated ERK1/2 and p38 MAPK. Both antioxidants and COX-2 inhibitors normalized superoxide anion production, NADPH oxidase activity and mRNA levels of NOX-1, NOX-4 and COX-2. Blockade of the ERK1/2 and p38 signaling pathways abolished lead-induced NOX-1, NOX-4 and COX-2 expression. Results show that lead activation of the MAPK signaling pathways activates inflammatory proteins such as NADPH oxidase and COX-2, suggesting a reciprocal interplay and contribution to vascular dysfunction as an underlying mechanisms for lead-induced hypertension. - Highlights: • Lead-exposure increases oxidative stress, COX-2 expression and vascular reactivity. • Lead exposure activates MAPK signaling pathway. • ROS and COX-2 activation by

  20. Local tetrahydrobiopterin administration augments reflex cutaneous vasodilation through nitric oxide-dependent mechanisms in aged human skin

    OpenAIRE

    Stanhewicz, Anna E.; Bruning, Rebecca S.; Smith, Caroline J.; Kenney, W. Larry; Holowatz, Lacy A.

    2011-01-01

    Functional constitutive nitric oxide synthase (NOS) is required for full expression of reflex cutaneous vasodilation that is attenuated in aged skin. Both the essential cofactor tetrahydrobiopterin (BH4) and adequate substrate concentrations are necessary for the functional synthesis of nitric oxide (NO) through NOS, both of which are reduced in aged vasculature through increased oxidant stress and upregulated arginase, respectively. We hypothesized that acute local BH4 administration or argi...

  1. Characteristic of the Oxidative Stress in Blood of Patients in Dependence of Community-Acquired Pneumonia Severity

    OpenAIRE

    Larissa Muravlyova; Vilen Molotov–Luchankiy; Ryszhan Bakirova; Dmitriy Klyuyev; Ludmila Demidchik; Valentina Lee

    2016-01-01

    BACKGROUND: At the present time the alternation of the oxidative metabolism is considered as one of the leading pathogenic mechanisms in the development and progression of community-acquired pneumonia (CAP). However the nature and direction of the oxidative protein changes in CAP patient’s blood had been almost unexplored. AIM: To define oxidative and modified proteins in erythrocytes and blood plasma of CAP patients. MATERIAL AND METHODS: Blood plasma and erythrocytes obtained from: ...

  2. Anaerobic nitrite-dependent methane-oxidizing bacteria - novel participants in methane cycling of drained peatlands ecosystems

    Science.gov (United States)

    Kravchenko, Irina; Sukhacheva, Marina; Menko, Ekaterina; Sirin, Andrey

    2014-05-01

    Northern peatlands are one of the key sources of atmospheric methane. Process-based studies of methane dynamic are based on the hypothesis of the balance between microbial methane production and oxidation, but this doesn't explain all variations in and constraints on peatland CH4 emissions. One of the reasons for this discrepancy could be anaerobic methane oxidation (AOM) - the process which is still poorly studied and remained controversial. Very little is known about AOM in peatlands, where it could work as an important 'internal' sink for CH4. This lack of knowledge primarily originated from researchers who generally consider AOM quantitatively insignificant or even non-existent in northern peatland ecosystems. But not far ago, Smemo and Yavitt (2007) presented evidence for AOM in freshwater peatlands used indirect techniques including isotope dilution assays and selective methanogenic inhibitors. Nitrite-dependent anaerobic methane oxidation NC10 group bacteria (n-damo) were detected in a minerotrophic peatland in the Netherlands that is infiltrated by nitrate-rich ground water (Zhu et al., 2012). Present study represents the first, to our knowledge, characterization of AOM in human disturbed peatlands, including hydrological elements of artificial drainage network. The experiments were conducted with samples of peat from drained peatlands, as well as of water and bottom sediments of ditches from drained Dubnensky mire massif, Moscow region (Chistotin et al., 2006; Sirin et al., 2012). This is the key testing area of our research group in European part of Russia for the long-term greenhouse gases fluxes measurements supported by testing physicochemical parameters, intensity and genomic diversity of CH4-cycling microbial communities. Only in sediments of drainage ditches the transition anaerobic zone was found, where methane and nitrate occurred, suggested the possible ecological niche for n-damo bacteria. The NC10 group methanotrophs were analyzed by PCR

  3. A time-dependent direct current potential drop method to evaluate thickness of an oxide layer formed naturally and thermally on a large surface of carbon steel

    International Nuclear Information System (INIS)

    This study describes the use of a time-dependent spring-loaded four-point-probe technique to measure the direct current potential drop (DCPD) on oxidized test surfaces for different spring force values, with the purpose of evaluating the thickness of the oxide layer. The force of the spring attached to the current probe was reduced by inserting spacers with different thicknesses under the supporting legs of the sensor block. The PD measurement was first performed on machined sample exposed to the atmosphere for approximately 6 months. The sample was made of carbon steel (SS400). Then, the thickness of the oxide layer formed on the surface of the sample was increased by heat treatment. The PD was also measured on the samples subjected to heat treatment. The measurements were performed at different locations on the test surface under the same experimental conditions. The experimental results establish a relationship between the spring force and the time required for the current probe to penetrate the oxide layer. This article also proposes a procedure for evaluating the thickness of the oxide layer. Finally, the proposed method was used to evaluate the thickness of the oxide layer formed on a large surface. The method was performed to evaluate thickness of single phase monolayer oxide in the range of 3.5–8.7 μm. To demonstrate the validity and accuracy of the proposed method, the obtained thickness was compared to the thickness measured directly using a field emission scanning electron microscopy. - Highlights: ► Four-point-probe direct current potential drop technique. ► Naturally and thermally formed oxide layer on a large metallic surface. ► A procedure for evaluation of thickness of oxide layer formed on hot-rolled steel.

  4. Analysis of Time Dependent Low Level Exposure to Gallium Arsenide on Blood ALAD activity, Glutathione and Lipid per oxidation levels in Rat Blood, Liver and Kidney

    Directory of Open Access Journals (Sweden)

    Braham Deo Gupta

    2015-06-01

    Full Text Available Gallium arsenide (GaAs, an intermetallic semiconductor has widespread applications in the electronic industry. GaAs has the ability to dissociate into its constitutive moieties, arsenic and gallium which might be responsible for the oxidative stress. The present study was aimed at evaluating, effect of gallium arsenide on blood ALAD activity, glutathione and lipid per oxidation levels in rat blood, liver and kidney on exposure of 1, 2 and 6 months. Result indicated that arsenic moiety in GaAs was mainly responsible for causing oxidative stress via increased TBARS levels, decreased glutathione levels in blood and tissues. We also noted the decreased activity of ALAD in rat blood on exposure to gallium arsenide. The study demonstrates that the time dependent exposure to low level gallium arsenide led to increased in lipid per oxidation, decrease glutathione level and ALAD activity which concludes that the slow release of arsenic moiety from GaAs is mainly responsible for oxidative stress in rats and exerts its toxicity in time dependent manner related to its dissolution and maximum toxicity by increasing the time period of exposure.

  5. Temperature and frequency dependence of transport phenomena in co-doped rare earth oxides nanoparticles for ITSOFCs

    International Nuclear Information System (INIS)

    Highlights: • Phase pure ceria (Gd–La and Gd–Nd co-doped) as electrolytes for fuel cells. • Facile synthesis is done with composite mediated hydrothermal method. • Significant variation in transport properties with doping concentration is observed. • The Raman spectra confirmed the targeted doping and increase of vacancy sites. • Maximum conductivity achieved was 1.78 S cm−1 for Ce0.5Gd0.25Nd0.25Oδ at 600 °C. - Abstract: The present study is focused on the conductivity enhancement of the doped ceria. Composite mediated hydrothermal method (CMHM) was employed to produce the material. X-ray diffraction was used to determine phase of nanocrystalline Ce1−2xGdxLaxOδ and Ce1−2xGdxNdxOδ (x = 0.1, 0.25). Conduction mechanism (dc conductivity and ac conductivity) in prepared samples was observed as a function of temperature and frequency. DC conductivity was measured in temperature range 300–700 °C. AC conductivity was measured in frequency range 1 kHz to 3 MHz at temperatures 300, 400, 500, 600, and 700 °C. The enhancement in conductivity was observed due to availability of oxygen vacancy sites which was dependent on composition. The Raman measurements supported the electrical conductivity results and more vacancy sites were observed in Raman spectrum in samples which showed maximum conductivities. The maximum conductivity achieved was 1.78 S cm−1 (at 600 °C) for Ce0.5Gd0.25Nd0.25Oδ, which is quite a higher value in these compounds. This made this material a potential candidate for its use as an electrolyte material for Intermediate Temperature Solid Oxide Fuel Cells (ITSOFCs)

  6. Formation of reactive nitrogen species at biologic heme centers: a potential mechanism of nitric oxide-dependent toxicity.

    Science.gov (United States)

    Casella, Luigi; Monzani, Enrico; Roncone, Raffaella; Nicolis, Stefania; Sala, Alberto; De Riso, Antonio

    2002-01-01

    The peroxidase-catalyzed nitration of tyrosine derivatives by nitrite and hydrogen peroxide has been studied in detail using the enzymes lactoperoxidase (LPO) from bovine milk and horseradish peroxidase (HRP). The results indicate the existence of two competing pathways, in which the nitrating species is either nitrogen dioxide or peroxynitrite. The first pathway involves one-electron oxidation of nitrite by the classical peroxidase intermediates compound I and compound II, whereas in the second pathway peroxynitrite is generated by reaction between enzyme-bound nitrite and hydrogen peroxide. The two mechanisms can be simultaneously operative, and their relative importance depends on the reagent concentrations. With HRP the peroxynitrite pathway contributes significantly only at relatively high nitrite concentrations, but for LPO this represents the main pathway even at relatively low (pathophysiological) nitrite concentrations and explains the high efficiency of the enzyme in the nitration. Myoglobin and hemoglobin are also active in the nitration of phenolic compounds, albeit with lower efficiency compared with peroxidases. In the case of myoglobin, endogenous nitration of the protein has been shown to occur in the absence of substrate. The main nitration site is the heme, but a small fraction of nitrated Tyr146 residue has been identified upon proteolytic digestion and high-performance liquid chromatography/mass spectrometry analysis of the peptide fragments. Preliminary investigation of the nitration of tryptophan derivatives by the peroxidase/nitrite/hydrogen peroxide systems shows that a complex pattern of isomeric nitration products is produced, and this pattern varies with nitrite concentration. Comparative experiments using chemical nitrating agents indicate that at low nitrite concentrations, the enzymatic nitration produces a regioisomeric mixture of nitrotryptophanyl derivatives resembling that obtained using nitrogen dioxide, whereas at high nitrite

  7. Angiopoietin-like 4 mediates PPAR delta effect on lipoprotein lipase-dependent fatty acid uptake but not on beta-oxidation in myotubes.

    Directory of Open Access Journals (Sweden)

    Marius R Robciuc

    Full Text Available Peroxisome proliferator-activated receptor (PPAR delta is an important regulator of fatty acid (FA metabolism. Angiopoietin-like 4 (Angptl4, a multifunctional protein, is one of the major targets of PPAR delta in skeletal muscle cells. Here we investigated the regulation of Angptl4 and its role in mediating PPAR delta functions using human, rat and mouse myotubes. Expression of Angptl4 was upregulated during myotubes differentiation and by oleic acid, insulin and PPAR delta agonist GW501516. Treatment with GW501516 or Angptl4 overexpression inhibited both lipoprotein lipase (LPL activity and LPL-dependent uptake of FAs whereas uptake of BSA-bound FAs was not affected by either treatment. Activation of retinoic X receptor (RXR, PPAR delta functional partner, using bexarotene upregulated Angptl4 expression and inhibited LPL activity in a PPAR delta dependent fashion. Silencing of Angptl4 blocked the effect of GW501516 and bexarotene on LPL activity. Treatment with GW501516 but not Angptl4 overexpression significantly increased palmitate oxidation. Furthermore, Angptl4 overexpression did not affect the capacity of GW501516 to increase palmitate oxidation. Basal and insulin stimulated glucose uptake, glycogen synthesis and glucose oxidation were not significantly modulated by Angptl4 overexpression. Our findings suggest that FAs-PPARdelta/RXR-Angptl4 axis controls the LPL-dependent uptake of FAs in myotubes, whereas the effect of PPAR delta activation on beta-oxidation is independent of Angptl4.

  8. Characteristic of the Oxidative Stress in Blood of Patients in Dependence of Community-Acquired Pneumonia Severity

    Science.gov (United States)

    Muravlyova, Larissa; Molotov–Luchankiy, Vilen; Bakirova, Ryszhan; Klyuyev, Dmitriy; Demidchik, Ludmila; Lee, Valentina

    2016-01-01

    BACKGROUND: At the present time the alternation of the oxidative metabolism is considered as one of the leading pathogenic mechanisms in the development and progression of community-acquired pneumonia (CAP). However the nature and direction of the oxidative protein changes in CAP patient’s blood had been almost unexplored. AIM: To define oxidative and modified proteins in erythrocytes and blood plasma of CAP patients. MATERIAL AND METHODS: Blood plasma and erythrocytes obtained from: 42 patients with moderate severity pneumonia, 12 patients with grave severity pneumonia and 32 healthy volunteers. Content of advanced oxidation protein products, malondialdehyde and reactive carbonyl derivatives were estimated as indicators of the oxidative stress and oxidative damage of proteins. RESULTS: In patients with grave severity the level of oxidative proteins and MDA in erythrocytes exceeded both: control values and similar meanings in CAP patients with moderate severity. The further growth of MDA in this group patients’ blood plasma was observed, but the level of oxidative proteins decreased in comparison with those in CAP patients with moderate severity. CONCLUSION: To sum up, our derived data show, that injury of erythrocytes’ redox-status and blood plasma components plays an essential role in development and progression CAP. PMID:27275344

  9. Characteristic of the Oxidative Stress in Blood of Patients in Dependence of Community-Acquired Pneumonia Severity

    Directory of Open Access Journals (Sweden)

    Larissa Muravlyova

    2016-03-01

    Full Text Available BACKGROUND: At the present time the alternation of the oxidative metabolism is considered as one of the leading pathogenic mechanisms in the development and progression of community-acquired pneumonia (CAP. However the nature and direction of the oxidative protein changes in CAP patient’s blood had been almost unexplored. AIM: To define oxidative and modified proteins in erythrocytes and blood plasma of CAP patients. MATERIAL AND METHODS: Blood plasma and erythrocytes obtained from: 42 patients with moderate severity pneumonia, 12 patients with grave severity pneumonia and 32 healthy volunteers. Content of advanced oxidation protein products, malondialdehyde and reactive carbonyl derivatives were estimated as indicators of the oxidative stress and oxidative damage of proteins. RESULTS: In patients with grave severity the level of oxidative proteins and MDA in erythrocytes exceeded both: control values and similar meanings in CAP patients with moderate severity. The further growth of MDA in this group patients’ blood plasma was observed, but the level of oxidative proteins decreased in comparison with those in CAP patients with moderate severity. CONCLUSION: To sum up, our derived data show, that injury of erythrocytes’ redox-status and blood plasma components plays an essential role in development and progression CAP.

  10. Propofol Protects Against H2O2-Induced Oxidative Injury in Differentiated PC12 Cells via Inhibition of Ca(2+)-Dependent NADPH Oxidase.

    Science.gov (United States)

    Chen, Xiao-Hui; Zhou, Xue; Yang, Xiao-Yu; Zhou, Zhi-Bin; Lu, Di-Han; Tang, Ying; Ling, Ze-Min; Zhou, Li-Hua; Feng, Xia

    2016-05-01

    Propofol (2,6-diisopropylphenol) is a widely used general anesthetic with anti-oxidant activities. This study aims to investigate protective capacity of propofol against hydrogen peroxide (H2O2)-induced oxidative injury in neural cells and whether the anti-oxidative effects of propofol occur through a mechanism involving the modulation of NADPH oxidase (NOX) in a manner of calcium-dependent. The rat differentiated PC12 cell was subjected to H2O2 exposure for 24 h to mimic a neuronal in vitro model of oxidative injury. Our data demonstrated that pretreatment of PC12 cells with propofol significantly reversed the H2O2-induced decrease in cell viability, prevented H2O2-induced morphological changes, and reduced the ratio of apoptotic cells. We further found that propofol attenuated the accumulation of malondialdehyde (biomarker of oxidative stress), counteracted the overexpression of NOX core subunit gp91(phox) (NOX2) as well as the NOX activity following H2O2 exposure in PC12 cells. In addition, blocking of L-type Ca(2+) channels with nimodipine reduced H2O2-induced overexpression of NOX2 and caspase-3 activation in PC12 cells. Moreover, NOX inhibitor apocynin alone or plus propofol neither induces a significant downregulation of NOX activity nor increases cell viability compared with propofol alone in the PC12 cells exposed to H2O2. These results demonstrate that the protective effects of propofol against oxidative injury in PC12 cells are mediated, at least in part, through inhibition of Ca(2+)-dependent NADPH oxidase. PMID:26162968

  11. Dose-dependent effects of dietary zinc oxide on bacterial communities and metabolic profiles in the ileum of weaned pigs.

    Science.gov (United States)

    Pieper, R; Vahjen, W; Neumann, K; Van Kessel, A G; Zentek, J

    2012-10-01

    Pharmacological levels of zinc oxide (ZnO) can improve the health of weaning piglets and influence the intestinal microbiota. This experiment aimed at studying the dose-response effect of five dietary concentrations of ZnO on small intestinal bacteria and metabolite profiles. Fifteen piglets, weaned at 25 ± 1 days of age, were allocated into five groups according to body weight and litter. Diets were formulated to contain 50 (basal diet), 150, 250, 1000 and 2500 mg zinc/kg by adding analytical-grade (>98% purity) ZnO to the basal diet and fed ad libitum for 14 days after a 7-day adaptation period on the basal diet. Ileal bacterial community profiles were analysed by denaturing gradient gel electrophoresis and selected bacterial groups quantified by real-time PCR. Concentrations of ileal volatile fatty acids (VFA), D- and L-lactate and ammonia were determined. Species richness, Shannon diversity and evenness were significantly higher at high ZnO levels. Quantitative PCR revealed lowest total bacterial counts in the 50 mg/kg group. Increasing ZnO levels led to an increase (p = 0.017) in enterobacteria from log 4.0 cfu/g digesta (50 mg/kg) to log 6.7 cfu/g digesta (2500 mg/kg). Lactic acid bacteria were not influenced (p = 0.687) and clostridial cluster XIVa declined (p = 0.035) at highest ZnO level. Concentration of total, D- and L-lactate and propionate was not affected (p = 0.736, p = 0.290 and p = 0.630), but concentrations of ileal total VFA, acetate and butyrate increased markedly from 50 to 150 mg/kg and decreased with further increasing zinc levels and reached low levels again at 2500 mg/kg (p = 0.048, p = 0.048 and p = 0.097). Ammonia decreased (p < 0.006) with increasing dietary ZnO level. In conclusion, increasing levels of dietary ZnO had strong and dose-dependent effects on ileal bacterial community composition and activity, suggesting taxonomic variation in metabolic response to ZnO. PMID:21929727

  12. Oxidative stress induced by palytoxin in human keratinocytes is mediated by a H+-dependent mitochondrial pathway

    International Nuclear Information System (INIS)

    In the last decades, massive blooms of palytoxin (PLTX)-producing Ostreopsis cf. ovata have been observed along Mediterranean coasts, usually associated to human respiratory and cutaneous problems. At the molecular level, PLTX induces a massive intracellular Na+ influx due to the transformation of Na+/K+ ATPase in a cationic channel. Recently, we have demonstrated that Na+ overload is the crucial step in mediating overproduction of reactive oxygen species (ROS) and cell death in human HaCaT keratinocytes, tentatively explaining PLTX-induced skin irritant effects. In the present study the molecular mechanisms of ROS production induced by PLTX-mediated Na+ intracellular overload have been investigated. In HaCaT cells, PLTX exposure caused accumulation of superoxide anion, but not of nitric oxide or peroxynitrite/hydroxyl radicals. Even if RT-PCR and western blot analysis revealed an early NOX-2 and iNOS gene and protein over-expressions, their active involvement seemed to be only partial since selective inhibitors did not completely reduce O2− production. A significant role of other enzymes (COX-1, COX-2, XO) was not evidenced. Nigericin, that counteracts Na+-mediated H+-imbalance, dissipating ΔpH across mitochondrial inner membrane, and the uncouplers DNP significantly reduced O2− production. These inhibitions were synergistic when co-exposed with complex-I inhibitor rotenone. These results suggest a novel mechanism of O2− production induced by PLTX-mediated ionic imbalance. Indeed, the H+ intracellular overload that follows PLTX-induced intracellular Na+ accumulation, could enhance ΔpH across mitochondrial inner membrane, that seems to be the driving force for O2− production by reversing mitochondrial electron transport. Highlights: ► PLTX induces superoxide (O2−) production by reversing mitochondrial transport chain. ► The mechanism of O2− production is dependent on PLTX-induced ionic imbalance. ► The results led to the proposal of a novel

  13. p53-Dependent and cell specific epigenetic regulation of the polo-like kinases under oxidative stress.

    Directory of Open Access Journals (Sweden)

    Alejandra Ward

    Full Text Available The polo-like kinase (PLKs family, consisting of five known members, are key regulators of important cell cycle processes, which include mitotic entry, centrosome duplication, spindle assembly, and cytokinesis. The PLKs have been implicated in a variety of cancers, such as hepatocellular carcinoma (HCC, with PLK1 typically overexpressed and PLKs 2-5 often downregulated. Altered expression of the PLKs in malignancy is often correlated with aberrant promoter methylation. Epigenetic marks are dynamic and can be modified in response to external environmental stimuli. The aim of our study was to determine if oxidative stress, a common feature of solid tumours, would induce changes to the promoter methylation of the PLKs resulting in changes in expression. We examined the promoter methylation status via MSP and subsequent expression levels of the PLK family members under exposure to hypoxic conditions or reactive oxygen species (ROS. Interestingly, murine embryonic fibroblasts exposed to hypoxia and ROS displayed significant hypermethylation of Plk1 and Plk4 promoter regions post treatment. Corresponding proteins were also depleted by 40% after treatment. We also examined the HCC-derived cell lines HepG2 and Hep3B and found that for PLK1 and PLK4, the increase in hypermethylation was correlated with the presence of functional p53. In p53 wild-type cells, HepG2, both PLK1 and PLK4 were repressed with treatment, while in the p53 null cell line, Hep3B, PLK4 protein was elevated in the presence of hypoxia and ROS. This was also the case for ROS-treated, p53 null, osteosarcoma cells, Saos-2, where the PLK4 promoter became hypomethylated and protein levels were elevated. Our data supports a model in which the PLKs are susceptible to epigenetic changes induced by microenvironmental cues and these modifications may be p53-dependent. This has important implications in HCC and other cancers, where epigenetic alterations of the PLKs could contribute to

  14. The dependence of dielectric parameters and electric conduction of composite on the base of polyethylene and iron oxide on radiation dose

    International Nuclear Information System (INIS)

    The radiation γ-influence at 0-500 kGy doses on dielectric parameters (ε and t gδ) and composite electric conduction (ζ) on the base of high-density polyethylene and iron oxide (α Fe2O3) radiated in air at room temperature is studied with the aim of modification of new class composite properties polymer -metal oxide.It is shown that ε=f(D) and tgδ=f(D) dependences have extreme character at(10 and 20 %) α-Fe2O3 high concentrations.ζ =f(D) dependence of investigated samples also has extreme character (besides composite high-density polyethylene +20% α-Fe2O3) and it is explained by accumulation of stabilized charge carriers in them

  15. Temperature dependent interfacial and electrical characteristics during atomic layer deposition and annealing of HfO2 films in p-GaAs metal-oxide-semiconductor capacitors

    Science.gov (United States)

    Chen, Liu; Yuming, Zhang; Yimen, Zhang; Hongliang, Lü; Bin, Lu

    2015-12-01

    We have investigated the temperature dependent interfacial and electrical characteristics of p-GaAs metal-oxide-semiconductor capacitors during atomic layer deposition (ALD) and annealing of HfO2 using the tetrakis (ethylmethyl) amino hafnium precursor. The leakage current decreases with the increase of the ALD temperature and the lowest current is obtained at 300 °C as a result of the Frenkel-Poole conduction induced leakage current being greatly weakened by the reduction of interfacial oxides at the higher temperature. Post deposition annealing (PDA) at 500 °C after ALD at 300 °C leads to the lowest leakage current compared with other annealing temperatures. A pronounced reduction in As oxides during PDA at 500 °C has been observed using X-ray photoelectron spectroscopy at the interface resulting in a proportional increase in Ga2O3. The increment of Ga2O3 after PDA depends on the amount of residual As oxides after ALD. Thus, the ALD temperature plays an important role in determining the high-k/GaAs interface condition. Meanwhile, an optimum PDA temperature is essential for obtaining good dielectric properties. Project supported by the Advance Research Project of China (No. 5130803XXXX) and the National Natural Science Foundation of China (No. 61176070).

  16. Oxidation Temperature Dependence of the Structural, Optical and Electrical Properties of SnO2 Thin Films

    Science.gov (United States)

    Boulainine, D.; Kabir, A.; Bouanane, I.; Boudjema, B.; Schmerber, G.

    2016-05-01

    In this work, SnO2 thin films were prepared by thermal oxidation of Sn in an oxygen-rich atmosphere. The Sn thin films were deposited onto Si (100) substrates by vacuum evaporation, and the properties of the oxide films were investigated as a function of the oxidation temperature. The x-ray diffraction patterns showed that the obtained films have a polycrystalline structure with a preferential orientation along the (101) plane. The film oxidized at 500°C was not completely oxidized. The grain growth of the films was controlled by the pore mobility process. The UV-Vis reflectance spectra revealed an increase in both the refractive index and density of the films, reflecting the densification of the investigated films. The band gap energy decreased from 3.78 eV to 3.62 eV, caused by an increase in charge carrier density due to increased grain size. The increase in film thickness can be explained by the upward diffusion of tin atoms into the oxide film surface and the downward diffusion of oxygen atoms into the metal. The increase in the O/Sn ratio, determined from Rutherford backscattering spectroscopy, indicated enhanced material stoichiometry. Electrical resistivity decreased from 9.7 × 10-3 Ω cm to 1.7 × 10-4 Ω cm, which was attributed to the increased grain size.

  17. Vasodilator efficiency of endogenous prostanoids, Ca2+-activated K+ channels and nitric oxide in rats with spontaneous, salt-dependent or NO-deficient hypertension

    Czech Academy of Sciences Publication Activity Database

    Behuliak, Michal; Pintérová, Mária; Kuneš, Jaroslav; Zicha, Josef

    2011-01-01

    Roč. 34, č. 8 (2011), s. 968-975. ISSN 0916-9636 R&D Projects: GA ČR(CZ) GA305/09/0336; GA AV ČR(CZ) IAA500110902; GA MŠk(CZ) 1M0510 Institutional research plan: CEZ:AV0Z50110509 Keywords : Ca2+-activated K+ channels * nitric oxide-dependent vasodilatation * prostacyclin Subject RIV: ED - Physiology Impact factor: 2.576, year: 2011

  18. Phosphorylation of N-methyl-D-aspartic acid receptor-associated neuronal nitric oxide synthase depends on estrogens and modulates hypothalamic nitric oxide production during the ovarian cycle.

    OpenAIRE

    Parkash, Jyoti; d'Anglemont de Tassigny, Xavier; Bellefontaine, Nicole; Campagne, Celine; Mazure, Danièle; Buée-Scherrer, Valérie; Prevot, Vincent

    2010-01-01

    Within the preoptic region, nitric oxide (NO) production varies during the ovarian cycle and has the ability to impact hypothalamic reproductive function. One mechanism for the regulation of NO release mediated by estrogens during the estrous cycle includes physical association of the calcium-activated neuronal NO synthase (nNOS) enzyme with the glutamate N-methyl-d-aspartate (NMDA) receptor channels via the postsynaptic density 95 scaffolding protein. Here we demonstrate that endogenous vari...

  19. Modeling on oxide dependent 2DEG sheet charge density and threshold voltage in AlGaN/GaN MOSHEMT

    Science.gov (United States)

    Panda, J.; Jena, K.; Swain, R.; Lenka, T. R.

    2016-04-01

    We have developed a physics based analytical model for the calculation of threshold voltage, two dimensional electron gas (2DEG) density and surface potential for AlGaN/GaN metal oxide semiconductor high electron mobility transistors (MOSHEMT). The developed model includes important parameters like polarization charge density at oxide/AlGaN and AlGaN/GaN interfaces, interfacial defect oxide charges and donor charges at the surface of the AlGaN barrier. The effects of two different gate oxides (Al2O3 and HfO2) are compared for the performance evaluation of the proposed MOSHEMT. The MOSHEMTs with Al2O3 dielectric have an advantage of significant increase in 2DEG up to 1.2 × 1013 cm‑2 with an increase in oxide thickness up to 10 nm as compared to HfO2 dielectric MOSHEMT. The surface potential for HfO2 based device decreases from 2 to ‑1.6 eV within 10 nm of oxide thickness whereas for the Al2O3 based device a sharp transition of surface potential occurs from 2.8 to ‑8.3 eV. The variation in oxide thickness and gate metal work function of the proposed MOSHEMT shifts the threshold voltage from negative to positive realizing the enhanced mode operation. Further to validate the model, the device is simulated in Silvaco Technology Computer Aided Design (TCAD) showing good agreement with the proposed model results. The accuracy of the developed calculations of the proposed model can be used to develop a complete physics based 2DEG sheet charge density and threshold voltage model for GaN MOSHEMT devices for performance analysis.

  20. Sex-dependent compensated oxidative stress in the mouse liver upon deletion of catechol O-methyltransferase.

    Science.gov (United States)

    Tenorio-Laranga, Jofre; Männistö, Pekka T; Karayiorgou, Maria; Gogos, Joseph A; García-Horsman, J Arturo

    2009-05-01

    Catechol-O-methyl transferase (COMT) methylates catechols, such as L-dopa and dopamine, and COMT deficient mice show dramatic shifts in the metabolite levels of catechols. Increase in catechol metabolite levels can, in principle, lead to oxidative stress but no indices of oxidative stress have been reported in COMT-knockout (KO) mice [Forsberg MM, Juvonen RO, Helisalmi P, Leppanen J, Gogos JA, Karayiorgou M, et al. Lack of increased oxidative stress in catechol-O-methyltransferase (COMT)-deficient mice. Naunyn Schmiedebergs Arch Pharmacol 2004;370:279-89.]. Here we perform a proteomic based analysis of the livers of COMT-KO mice in search for potential compensatory mechanisms developed to cope with the effects of disrupted catechol metabolism. We found sex specific changes in proteins connected to stress response. Our results show that alterations in protein levels contribute to the homeostatic regulation in the liver of COMT deficient mice. PMID:19426692

  1. Human prostaglandin H synthase (hPHS)-1- and hPHS-2-dependent bioactivation, oxidative macromolecular damage, and cytotoxicity of dopamine, its precursor, and its metabolites.

    Science.gov (United States)

    Ramkissoon, Annmarie; Wells, Peter G

    2011-01-15

    The dopamine (DA) precursor l-dihydroxyphenylalanine (L-DOPA) and metabolites dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 3-methoxytyramine may serve as substrates for prostaglandin H synthase (PHS)-catalyzed bioactivation to free radical intermediates. We used CHO-K1 cells expressing human (h) PHS-1 or hPHS-2 to investigate hPHS isozyme-dependent oxidative damage and cytotoxicity. hPHS-1- and hPHS-2-expressing cells incubated with DA, L-DOPA, DOPAC, or HVA exhibited increased cytotoxicity compared to untransfected cells, and cytotoxicity was increased further by exogenous arachidonic acid (AA), which increased hPHS activity. Preincubation with catalase, which detoxifies reactive oxygen species, or acetylsalicylic acid, an inhibitor of hPHS-1 and -2, reduced the cytotoxicity caused by DA, L-DOPA, DOPAC, and HVA in hPHS-1 and -2 cells both with and without AA. Protein oxidation was increased in hPHS-1 and -2 cells exposed to DA or L-DOPA and further increased by AA addition. DNA oxidation was enhanced earlier and at lower substrate concentrations than protein oxidation in both hPHS-1 and -2 cells by DA, L-DOPA, DOPAC, and HVA and further enhanced by AA addition. hPHS-2 cells seemed more susceptible than hPHS-1 cells, whereas untransfected CHO-K1 cells were less susceptible. Thus, isozyme-specific, hPHS-dependent oxidative damage and cytotoxicity caused by neurotransmitters, their precursors, and their metabolites may contribute to neurodegeneration associated with aging. PMID:21078384

  2. Fatty acid-binding protein 4 impairs the insulin-dependent nitric oxide pathway in vascular endothelial cells

    OpenAIRE

    Aragonès Gemma; Saavedra Paula; Heras Mercedes; Cabré Anna; Girona Josefa; Masana Lluís

    2012-01-01

    Abstract Background Recent studies have shown that fatty acid-binding protein 4 (FABP4) plasma levels are associated with impaired endothelial function in type 2 diabetes (T2D). In this work, we analysed the effect of FABP4 on the insulin-mediated nitric oxide (NO) production by endothelial cells in vitro. Methods In human umbilical vascular endothelial cells (HUVECs), we measured the effects of FABP4 on the insulin-mediated endothelial nitric oxide synthase (eNOS) expression and activation a...

  3. Transient hypoxia stimulates mitochondrial biogenesis in brain subcortex by a neuronal nitric oxide synthase-dependent mechanism

    Science.gov (United States)

    The adaptive mechanisms that protect brain metabolism during and after hypoxia, for instance, during hypoxic preconditioning, are coordinated in part by nitric oxide (NO). We tested the hypothesis that acute transient hypoxia stimulates NO synthase (NOS)-activated mechanisms of m...

  4. Dependence Properties of Sol-Gel Derived CuO@SiO2 Nanostructure to Diverse Concentrations of Copper Oxide

    Directory of Open Access Journals (Sweden)

    V. Homaunmir

    2013-01-01

    Full Text Available Various concentrations of copper oxide were embedded into silica matrix of xerogel forms using copper source Cu(NO32·3H2O. The xerogel samples were prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS with determination of new molar ratios of the components by the sol-gel method. In this paper, three samples of copper oxide were doped into silica matrices using different concentrations. We obtained 10, 20, and 30 wt.% of copper oxide in silica matrices labeled as A, B, and C, respectively. The absorption and transmittance spectra of the gel matrices were treated at different concentrations by Uv-vis spectrophotometer. Quantities of water and transparency in the silica network change the spectral characteristics of Cu2+ ions in the host silica. Absorption spectra of the samples heated to higher concentration complete the conversion of Cu2+ ions to Cu+ ions. The effects of concentration of copper oxide were characterized by X-ray diffraction (XRD patterns, and the transmission electron microscope (TEM micrographs. Also, textural properties of samples were studied by surface area analysis (BET method at different concentrations.

  5. Establishing the potential dependent equilibrium oxide coverage on platinum in alkaline solution and its influence on the oxygen reduction

    DEFF Research Database (Denmark)

    Wiberg, Gustav; Arenz, Matthias

    2012-01-01

    Publication year: 2012 Source:Journal of Power Sources, Volume 217 Gustav K.H. Wiberg, Matthias Arenz The oxidation process of polycrystalline platinum subjected to alkaline solution is re-examined using a combination of cyclic voltammetry and potential hold techniques in Ar, H2 and O2 purged 0.1 M...

  6. Probing the structural dependency of photoinduced properties of colloidal quantum dots using metal-oxide photo-active substrates

    Energy Technology Data Exchange (ETDEWEB)

    Patty, Kira; Campbell, Quinn; Hamilton, Nathan; West, Robert G. [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Sadeghi, Seyed M., E-mail: seyed.sadeghi@uah.edu [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Nano and Micro Device Center, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Mao, Chuanbin [Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma 73019 (United States)

    2014-09-21

    We used photoactive substrates consisting of about 1 nm coating of a metal oxide on glass substrates to investigate the impact of the structures of colloidal quantum dots on their photophysical and photochemical properties. We showed during irradiation these substrates can interact uniquely with such quantum dots, inducing distinct forms of photo-induced processes when they have different cores, shells, or ligands. In particular, our results showed that for certain types of core-shell quantum dot structures an ultrathin layer of a metal oxide can reduce suppression of quantum efficiency of the quantum dots happening when they undergo extensive photo-oxidation. This suggests the possibility of shrinking the sizes of quantum dots without significant enhancement of their non-radiative decay rates. We show that such quantum dots are not influenced significantly by Coulomb blockade or photoionization, while those without a shell can undergo a large amount of photo-induced fluorescence enhancement via such blockade when they are in touch with the metal oxide.

  7. Alloantigen-induced, T-cell-dependent production of nitric oxide by macrophages infiltrating skin allografts in mice

    Czech Academy of Sciences Publication Activity Database

    Krulová, Magdalena; Zajícová, Alena; Frič, Jan; Holáň, Vladimír

    2002-01-01

    Roč. 15, - (2002), s. 108-116. ISSN 0934-0874 R&D Projects: GA ČR GA310/99/0360; GA MZd NI6659; GA MŠk LN00A026 Keywords : Allograft rejection , nitric oxide Subject RIV: EC - Immunology Impact factor: 2.520, year: 2002

  8. Macrophage activation by a vanadyl-aspirin complex is dependent on L-type calcium channel and the generation of nitric oxide

    International Nuclear Information System (INIS)

    Bone homeostasis is the result of a tight balance between bone resorption and bone formation where macrophage activation is believed to contribute to bone resorption. We have previously shown that a vanadyl(IV)-aspirin complex (VOAspi) regulates cell proliferation and differentiation of osteoblasts in culture. In this study, we assessed VOAspi and VO effects and their possible mechanism of action on a mouse macrophage cell line RAW 264.7. Both vanadium compounds inhibited cell proliferation in a dose-dependent manner. Nifedipine completely reversed the VOAspi-induced macrophage cytotoxicity, while it could not block the effect of VO. VOAspi also stimulated nitric oxide (NO) production, the oxidation of dihydrorhodamine 123 (DHR-123) and enhanced the expression of both constitutive and inducible isoforms of nitric oxide syntases (NOS). All these effects were abolished by nifedipine. Althogether our finding give evidence that VOAspi-induced macrophage cytotoxicity is dependent on L-type calcium channel and the generation of NO though the induction of eNOS and iNOS. Contrary, the parent compound VO exerted a cytotoxic effect by mechanisms independent of a calcium entry and the NO/NOS activation

  9. Ginsenoside Rg3 increases nitric oxide production via increases in phosphorylation and expression of endothelial nitric oxide synthase: Essential roles of estrogen receptor-dependent PI3-kinase and AMP-activated protein kinase

    International Nuclear Information System (INIS)

    We previously showed that ginsenosides increase nitric oxide (NO) production in vascular endothelium and that ginsenoside Rg3 (Rg3) is the most active one among ginseng saponins. However, the mechanism for Rg3-mediated nitric oxide production is still uncertain. In this study, we determined whether Rg3 affects phosphorylation and expression of endothelial nitric oxide synthase (eNOS) in ECV 304 human endothelial cells. Rg3 increased both the phosphorylation and the expression of eNOS in a concentration-dependent manner and a maximal effect was found at 10 μg/ml of Rg3. The enzyme activities of phosphatidylinositol 3-kinase (PI3-kinase), c-Jun N-terminal kinase (JNK), and p38 kinase were enhanced as were estrogen receptor (ER)- and glucocorticoid receptor (GR)-dependent reporter gene transcriptions in Rg3-treated endothelial cells. Rg3-induced eNOS phosphorylation required the ER-mediated PI3-kinase/Akt pathway. Moreover, Rg3 activates AMP-activated protein kinase (AMPK) through up-regulation of CaM kinase II and Rg3-stimulated eNOS phosphorylation was reversed by AMPK inhibition. The present results provide a mechanism for Rg3-stimulated endothelial NO production.

  10. Biocomposite based on reduced graphene oxide film modified with phenothiazone and flavin adenine dinucleotide-dependent glucose dehydrogenase for glucose sensing and biofuel cell applications.

    Science.gov (United States)

    Ravenna, Yehonatan; Xia, Lin; Gun, Jenny; Mikhaylov, Alexey A; Medvedev, Alexander G; Lev, Ovadia; Alfonta, Lital

    2015-10-01

    A novel composite material for the encapsulation of redox enzymes was prepared. Reduced graphene oxide film with adsorbed phenothiazone was used as a highly efficient composite for electron transfer between flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase and electrodes. Measured redox potential for glucose oxidation was lower than 0 V vs Ag/AgCl electrode. The fabricated biosensor showed high sensitivity of 42 mA M(-1) cm(-2), a linear range of glucose detection of 0.5-12 mM, and good reproducibility and stability as well as high selectivity for different interfering compounds. In a semibiofuel cell configuration, the hybrid film generated high power output of 345 μW cm(-2). These results demonstrate a promising potential for this composition in various bioelectronic applications. PMID:26334692

  11. Field Dependence of the Spin Relaxation Within a Film of Iron Oxide Nanocrystals Formed via Electrophoretic Deposition

    OpenAIRE

    Hasan SA; Mahajan SV; J-H. Park; Kavich DW; Dickerson JH

    2010-01-01

    Abstract The thermal relaxation of macrospins in a strongly interacting thin film of spinel-phase iron oxide nanocrystals (NCs) is probed by vibrating sample magnetometry (VSM). Thin films are fabricated by depositing FeO/Fe3O4 core–shell NCs by electrophoretic deposition (EPD), followed by sintering at 400°C. Sintering transforms the core–shell structure to a uniform spinel phase, which effectively increases the magnetic moment per NC. Atomic force microscopy (AFM) confirms ...

  12. l-Arginine-dependent suppression of apoptosis in Trypanosoma cruzi: Contribution of the nitric oxide and polyamine pathways

    OpenAIRE

    Piacenza, Lucía; Peluffo, Gonzalo; Radi, Rafael

    2001-01-01

    Until recently, a capacity for apoptosis and synthesis of nitric oxide (⋅NO) were viewed as exclusive to multicellular organisms. The existence of these processes in unicellular parasites was recently described, with their biological significance remaining to be elucidated. We have evaluated l-arginine metabolism in Trypanosoma cruzi in the context of human serum-induced apoptotic death. Apoptosis was evidenced by the induction of DNA fragmentation and the inhi...

  13. Microtubule dysfunction by posttranslational nitrotyrosination of α-tubulin: A nitric oxide-dependent mechanism of cellular injury

    OpenAIRE

    Eiserich, Jason P.; Estévez, Alvaro G.; Bamberg, Thaddeus V.; Ye, Yao Zu; Chumley, Phillip H.; Beckman, Joseph S.; Freeman, Bruce A.

    1999-01-01

    NO2Tyr (3-Nitrotyrosine) is a modified amino acid that is formed by nitric oxide-derived species and has been implicated in the pathology of diverse human diseases. Nitration of active-site tyrosine residues is known to compromise protein structure and function. Although free NO2Tyr is produced in abundant concentrations under pathological conditions, its capacity to alter protein structure and function at the translational or posttranslational level is unknown. Here, we report that free NO2T...

  14. Involvement of nitric oxide in the jasmonate-dependent basal defense against root-knot nematode in tomato plants

    OpenAIRE

    Zhou, Jie; Jia, Feifei; Shao, Shujun; Zhang, Huan; Guiping LI; Xia, Xiaojian; Zhou, Yanhong; Yu, Jingquan; Shi, Kai

    2015-01-01

    Jasmonic acid (JA) and nitric oxide (NO) are well-characterized signaling molecules in plant defense responses. However, their roles in plant defense against root-knot nematode (RKN, Meloidogyne incognita) infection are largely unknown. In this study, we found that the transcript levels of the JA- and NO-related biosynthetic and signaling component genes were induced after RKN infection. Application of exogenous JA and sodium nitroprusside (SNP; a NO donor) significantly decreased the number ...

  15. Time and Dose-Dependent Effects of Labisia pumila on Bone Oxidative Status of Postmenopausal Osteoporosis Rat Model

    OpenAIRE

    Nadia Mohd Effendy; Ahmad Nazrun Shuid

    2014-01-01

    Postmenopausal osteoporosis can be associated with oxidative stress and deterioration of antioxidant enzymes. It is mainly treated with estrogen replacement therapy (ERT). Although effective, ERT may cause adverse effects such as breast cancer and pulmonary embolism. Labisia pumila var. alata (LP), a herb used traditionally for women’s health was found to protect against estrogen-deficient osteoporosis. An extensive study was conducted in a postmenopausal osteoporosis rat model using several ...

  16. [2]Pseudorotaxane composed of heteroditopic macrobicycle and pyridine N-oxide based axle: recognition site dependent axle orientation.

    Science.gov (United States)

    Saha, Subrata; Santra, Saikat; Ghosh, Pradyut

    2015-04-17

    A strategy for threading an axle having a hydrogen bond acceptor unit in the cavity of a C3v symmetric amido-amine macrobicycle is investigated. The macrobicycle acts as a wheel in its neutral as well as triprotonated states to form threaded architectures with a pyridine N-oxide derivative. The negative oxygen dipole of the axle is capable of [2]pseudorotaxane formation in two different orientations with the wheel in its neutral and triprotonated states. PMID:25825821

  17. Molecular hydrogen regulates gene expression by modifying the free radical chain reaction-dependent generation of oxidized phospholipid mediators

    OpenAIRE

    Katsuya Iuchi; Akemi Imoto; Naomi Kamimura; Kiyomi Nishimaki; Harumi Ichimiya; Takashi Yokota; Shigeo Ohta

    2016-01-01

    We previously showed that H2 acts as a novel antioxidant to protect cells against oxidative stress. Subsequently, numerous studies have indicated the potential applications of H2 in therapeutic and preventive medicine. Moreover, H2 regulates various signal transduction pathways and the expression of many genes. However, the primary targets of H2 in the signal transduction pathways are unknown. Here, we attempted to determine how H2 regulates gene expression. In a pure chemical system, H2 gas ...

  18. Alloantigen-induced, T-cell-dependent production of nitic oxide by macrophagesinfiltrating skin allografts in mice

    Czech Academy of Sciences Publication Activity Database

    Krulová, Magdalena; Zajícová, Alena; Frič, Jan; Holáň, Vladimír

    2002-01-01

    Roč. 15, 2-3 (2002), s. 108-116. ISSN 0934-0874 R&D Projects: GA ČR GA310/99/D044; GA ČR GA310/99/0360; GA MZd NI6659; GA MŠk LN00A026 Institutional research plan: CEZ:AV0Z5052915 Keywords : allograft rejection * macrophages * nitric oxide Subject RIV: EC - Immunology Impact factor: 2.520, year: 2002

  19. Alloantigen-induced, T-cell dependent production of nitric oxide by macrophages infiltrating skin allografts in mice

    Czech Academy of Sciences Publication Activity Database

    Krulová, Magdalena; Zajícová, Alena; Frič, Jan; Holáň, Vladimír

    15, 2002, 2-3 (2002), s. 108-116. ISSN 0934-0874 R&D Projects: GA ČR GA310/99/D044; GA ČR GA310/99/0360; GA MZd NI6659; GA MŠk LN00A026 Institutional research plan: CEZ:AV0Z5052915 Keywords : mouse * allograft rejection * nitric oxide Subject RIV: EC - Immunology Impact factor: 2.520, year: 2002

  20. Inhibition of IFN-γ-Induced Nitric Oxide Dependent Antimycobacterial Activity by miR-155 and C/EBPβ

    Directory of Open Access Journals (Sweden)

    Yongwei Qin

    2016-04-01

    Full Text Available miR-155 (microRNA-155 is an important non-coding RNA in regulating host crucial biological regulators. However, its regulatory function in mycobacterium infection remains unclear. Our study demonstrates that miR-155 expression is significantly increased in macrophages after Mycobacterium marinum (M.m infection. Transfection with anti-miR-155 enhances nitric oxide (NO synthesis and decreases the mycobacterium burden, and vice versa, in interferon γ (IFN-γ activated macrophages. More importantly, miR-155 can directly bind to the 3′UTR of CCAAT/enhancer binding protein β (C/EBPβ, a positive transcriptional regulator of nitric oxide synthase (NOS2, and regulate C/EBPβ expression negatively. Knockdown of C/EBPβ inhibit the production of nitric oxide synthase and promoted mycobacterium survival. Collectively, these data suggest that M.m-induced upregulation of miR-155 downregulated the expression of C/EBPβ, thus decreasing the production of NO and promoting mycobacterium survival, which may provide an insight into the function of miRNA in subverting the host innate immune response by using mycobacterium for its own profit. Understanding how miRNAs partly regulate microbicidal mechanisms may represent an attractive way to control tuberculosis infectious.

  1. Inhibition of IFN-γ-Induced Nitric Oxide Dependent Antimycobacterial Activity by miR-155 and C/EBPβ

    Science.gov (United States)

    Qin, Yongwei; Wang, Qinglan; Zhou, Youlang; Duan, Yinong; Gao, Qian

    2016-01-01

    miR-155 (microRNA-155) is an important non-coding RNA in regulating host crucial biological regulators. However, its regulatory function in mycobacterium infection remains unclear. Our study demonstrates that miR-155 expression is significantly increased in macrophages after Mycobacterium marinum (M.m) infection. Transfection with anti-miR-155 enhances nitric oxide (NO) synthesis and decreases the mycobacterium burden, and vice versa, in interferon γ (IFN-γ) activated macrophages. More importantly, miR-155 can directly bind to the 3′UTR of CCAAT/enhancer binding protein β (C/EBPβ), a positive transcriptional regulator of nitric oxide synthase (NOS2), and regulate C/EBPβ expression negatively. Knockdown of C/EBPβ inhibit the production of nitric oxide synthase and promoted mycobacterium survival. Collectively, these data suggest that M.m-induced upregulation of miR-155 downregulated the expression of C/EBPβ, thus decreasing the production of NO and promoting mycobacterium survival, which may provide an insight into the function of miRNA in subverting the host innate immune response by using mycobacterium for its own profit. Understanding how miRNAs partly regulate microbicidal mechanisms may represent an attractive way to control tuberculosis infectious. PMID:27070591

  2. Ropivacaine-Induced Contraction Is Attenuated by Both Endothelial Nitric Oxide and Voltage-Dependent Potassium Channels in Isolated Rat Aortae

    Directory of Open Access Journals (Sweden)

    Seong-Ho Ok

    2013-01-01

    Full Text Available This study investigated endothelium-derived vasodilators and potassium channels involved in the modulation of ropivacaine-induced contraction. In endothelium-intact rat aortae, ropivacaine concentration-response curves were generated in the presence or absence of the following inhibitors: the nonspecific nitric oxide synthase (NOS inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, the neuronal NOS inhibitor Nω-propyl-L-arginine hydrochloride, the inducible NOS inhibitor 1400W dihydrochloride, the nitric oxide-sensitive guanylyl cyclase (GC inhibitor ODQ, the NOS and GC inhibitor methylene blue, the phosphoinositide-3 kinase inhibitor wortmannin, the cytochrome p450 epoxygenase inhibitor fluconazole, the voltage-dependent potassium channel inhibitor 4-aminopyridine (4-AP, the calcium-activated potassium channel inhibitor tetraethylammonium (TEA, the inward-rectifying potassium channel inhibitor barium chloride, and the ATP-sensitive potassium channel inhibitor glibenclamide. The effect of ropivacaine on endothelial nitric oxide synthase (eNOS phosphorylation in human umbilical vein endothelial cells was examined by western blotting. Ropivacaine-induced contraction was weaker in endothelium-intact aortae than in endothelium-denuded aortae. L-NAME, ODQ, and methylene blue enhanced ropivacaine-induced contraction, whereas wortmannin, Nω-propyl-L-arginine hydrochloride, 1400W dihydrochloride, and fluconazole had no effect. 4-AP and TEA enhanced ropivacaine-induced contraction; however, barium chloride and glibenclamide had no effect. eNOS phosphorylation was induced by ropivacaine. These results suggest that ropivacaine-induced contraction is attenuated primarily by both endothelial nitric oxide and voltage-dependent potassium channels.

  3. Time and Dose-Dependent Effects of Labisia pumila on Bone Oxidative Status of Postmenopausal Osteoporosis Rat Model

    Directory of Open Access Journals (Sweden)

    Nadia Mohd Effendy

    2014-08-01

    Full Text Available Postmenopausal osteoporosis can be associated with oxidative stress and deterioration of antioxidant enzymes. It is mainly treated with estrogen replacement therapy (ERT. Although effective, ERT may cause adverse effects such as breast cancer and pulmonary embolism. Labisia pumila var. alata (LP, a herb used traditionally for women’s health was found to protect against estrogen-deficient osteoporosis. An extensive study was conducted in a postmenopausal osteoporosis rat model using several LP doses and duration of treatments to determine if anti-oxidative mechanisms were involved in its bone protective effects. Ninety-six female Sprague-Dawley rats were randomly divided into six groups; baseline group (BL, sham-operated (Sham, ovariectomised control (OVXC, ovariectomised (OVX and given 64.5 μg/kg of Premarin (ERT, ovariectomised and given 20 mg/kg of LP (LP20 and ovariectomised and given 100 mg/kg of LP (LP100. The groups were further subdivided to receive their respective treatments via daily oral gavages for three, six or nine weeks of treatment periods. Following euthanization, the femora were dissected out for bone oxidative measurements which include superoxide dismutase (SOD, glutathione peroxidase (GPx and malondialdehyde (MDA levels. Results: The SOD levels of the sham-operated and all the treatment groups were significantly higher than the OVX groups at all treatment periods. The GPx level of ERT and LP100 groups at the 9th week of treatment were significantly higher than the baseline and OVX groups. MDA level of the OVX group was significantly higher than all the other groups at weeks 6 and 9. The LP20 and LP100 groups at the 9th week of treatment had significantly lower MDA levels than the ERT group. There were no significant differences between LP20 and LP100 for all parameters. Thus, LP supplementations at both doses, which showed the best results at 9 weeks, may reduce oxidative stress which in turn may prevent bone loss via its

  4. Propofol restores TRPV1 sensitivity via a TRPA1-, nitric oxide synthase-dependent activation of PKCε

    OpenAIRE

    Sinharoy, Pritam; Zhang, Hongyu; Sinha, Sayantani; Prudner, Bethany C; Bratz, Ian N.; Damron, Derek S.

    2015-01-01

    We previously demonstrated that the intravenous anesthetic, propofol, restores the sensitivity of transient receptor potential vanilloid channel subtype-1 (TRPV1) receptors via a protein kinase C epsilon (PKCε)-dependent and transient receptor potential ankyrin channel subtype-1 (TRPA1)-dependent pathway in sensory neurons. The extent to which the two pathways are directly linked or operating in parallel has not been determined. Using a molecular approach, our objectives of the current study ...

  5. L-Arginine reverses the impairment of nitric oxide-dependent collateral perfusion in dietary-induced hypercholesterolaemia in the rabbit

    International Nuclear Information System (INIS)

    1. We have used an isolated, buffer-perfused, rabbit ear model of acute arterial occlusion to investigate the effects of exogenous L-arginine on the severe impairment of collateral perfusion associated with dietary-induced hypercholesterolaemia. The effects of L-arginine on hypercholesterolaemia-related impairment of endothelium-dependent relaxations to acetylcholine were also investigated in unligated, isolated rabbit ears perfused with buffer. 2. Cholesterol feeding for 8 weeks (blood cholesterol level 66.5 +/- 5.3 versus 1.4 +/- 0.2 mmol/l, P < 0.001) was associated with almost complete impairment of collateral perfusion, an effect previously observed after inhibition of nitric oxide synthesis. The impairment of collateral perfusion found in hypercholesterolaemia was completely reversed by the addition of 10 mmol/l L-arginine to the perfusion fluid. In control preparations from rabbits fed a normal diet, the addition of 10 mmol/l L-arginine did not influence collateral perfusion. 3. Endothelium-dependent relaxation to acetylcholine was impaired in preparations from the rabbits fed the high cholesterol diet for 8 weeks: the maximum relaxation of tone was 24.6 +/- 0.8% and was significantly (P < 0.01) less than that in the controls (70.3 +/- 2.4%). Addition of L-arginine to the perfusion fluid caused a modest improvement in the endothelium-dependent relaxations to acetylcholine, with a maximum response of 43.2 +/- 1.3%. 4. We conclude that nitric oxide-dependent collateral perfusion is severely impaired in hypercholesterolaemia and that the addition of exogenous L-arginine fully reverses these changes. Endothelium-dependent relaxations to acetylcholine are similarly impaired by hypercholesterolaemia; however, this deficit was only partially reversed by L-arginine

  6. Study of an Amorphous Silicon Oxide Buffer Layer for p-Type Microcrystalline Silicon Oxide/n-Type Crystalline Silicon Heterojunction Solar Cells and Their Temperature Dependence

    Directory of Open Access Journals (Sweden)

    Taweewat Krajangsang

    2014-01-01

    Full Text Available Intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H films were used as front and rear buffer layers in crystalline silicon heterojunction (c-Si-HJ solar cells. The surface passivity and effective lifetime of these i-a-SiO:H films on an n-type silicon wafer were improved by increasing the CO2/SiH4 ratios in the films. Using i-a-SiO:H as the front and rear buffer layers in c-Si-HJ solar cells was investigated. The front i-a-SiO:H buffer layer thickness and the CO2/SiH4 ratio influenced the open-circuit voltage (Voc, fill factor (FF, and temperature coefficient (TC of the c-Si-HJ solar cells. The highest total area efficiency obtained was 18.5% (Voc=700 mV, Jsc=33.5 mA/cm2, and FF=0.79. The TC normalized for this c-Si-HJ solar cell efficiency was −0.301%/°C.

  7. Calculation of constants of acid-base equilibria at the oxide-electrolyte interface from electrokinetic potential dependence on pH

    International Nuclear Information System (INIS)

    Method is proposed for calculating the constants of acid-base equilibria at the oxide-electrolyte interface. The method is based on the electrokinetic potential dependence on ph value at different electrolyte concentrations. It is shown that the calculated constant values for La2O3 and ZrO2 equal correspondingly 7.3 and 3.9 (pK10); 11.9 and 9.1 (pK20); 9.2 and 5.8 (pK30); 10.0 and 7.2 (pK40) agree well with literature data. 21 refs.; 3 figs.; 3 tabs

  8. Time-dependent effects of trimethylamine-N-oxide/urea on lactate dehydrogenase activity: an unexplored dimension of the adaptation paradigm.

    OpenAIRE

    Baskakov, I; Bolen, D. W.

    1998-01-01

    Given that enzymes in urea-rich cells are believed to be just as sensitive to urea effects as enzymes in non-urea-rich cells, it is argued that time-dependent inactivation of enzymes by urea could become a factor of overriding importance in the biology of urea-rich cells. Time-independent parameters (e.g. Tm, k(cat), and Km) involving protein stability and enzyme function have generally been the focus of inquiries into the efficacy of naturally occurring osmolytes like trimethylamine-N-oxide ...

  9. Development of thin film amorphous silicon oxide/microcrystalline silicon double-junction solar cells and their temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Sriprapha, K.; Piromjit, C.; Limmanee, A.; Sritharathikhun, J. [Institute of Solar Energy Technology Development (SOLARTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Road, Klong 1, Klong Luang, Pathumthani 12120 (Thailand)

    2011-01-15

    We have developed thin film silicon double-junction solar cells by using micromorph structure. Wide bandgap hydrogenated amorphous silicon oxide (a-SiO:H) film was used as an absorber layer of top cell in order to obtain solar cells with high open circuit voltage (V{sub oc}), which are attractive for the use in high temperature environment. All p, i and n layers were deposited on transparent conductive oxide (TCO) coated glass substrate by a 60 MHz-very-high-frequency plasma enhanced chemical vapor deposition (VHF-PECVD) technique. The p-i-n-p-i-n double-junction solar cells were fabricated by varying the CO{sub 2} and H{sub 2} flow rate of i top layer in order to obtain the wide bandgap with good quality material, which deposited near the phase boundary between a-SiO:H and hydrogenated microcrystalline silicon oxide ({mu}c-SiO:H), where the high V{sub oc} can be expected. The typical a-SiO:H/{mu}c-Si:H solar cell showed the highest initial cell efficiency of 10.5%. The temperature coefficient (TC) of solar cells indicated that the values of TC for conversion efficiency ({eta}) of the double-junction solar cells were inversely proportional to the initial V{sub oc}, which corresponds to the bandgap of the top cells. The TC for {eta} of typical a-SiO:H/{mu}c-Si:H was -0.32%/ C, lower than the value of conventional a-Si:H/{mu}c-Si:H solar cell. Both the a-SiO:H/{mu}c-Si:H solar cell and the conventional solar cell showed the same light induced degradation ratio of about 20%. We concluded that the solar cells using wide bandgap a-SiO:H film in the top cells are promising for the use in high temperature regions. (author)

  10. Positron studies of the temperature-dependence of free volumes in Polydimethylsiloxane/poly(propylene oxide) urethane/urea membranes

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira Marques, M.F. [Departamento de Engenharia Quimica, Instituto Superior de Engenharia, 3030-199 Coimbra (Portugal) and ICEMS, Departamento de Fisica, Universidade de Coimbra, 3004-516 Coimbra (Portugal)]. E-mail: fatima@lipc.fis.uc.pt; Gordo, P.M. [ICEMS, Departamento de Fisica, Universidade de Coimbra, 3004-516 Coimbra (Portugal); Kajcsos, Zs. [KFKI Research Institute for Particle and Nuclear Physics, H-1525 Budapest P.O.B.49 (Hungary); Lopes Gil, C. [ICEMS, Departamento de Fisica, Universidade de Coimbra, 3004-516 Coimbra (Portugal); Lima, A.P. de [ICEMS, Departamento de Fisica, Universidade de Coimbra, 3004-516 Coimbra (Portugal); Queiroz, D.P. [Departamento de Engenharia Quimica, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal); Pinho, M.N. de [Departamento de Engenharia Quimica, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal)

    2007-02-15

    Free-volume parameters in polyurethane/urea membranes have been studied by positron annihilation lifetime and Doppler broadening measurements. The bi-soft segment membranes were obtained by varying the ratio of the structural constituents, polypropylene oxide and polydimethylsiloxane (PU/PDMS), with PDMS content from 25 to 75 wt%. The free-volume holes determined by PALS are correlated with gas permeation features. The phase separation of the various soft and hard segments in the membranes is mirrored in both lifetime and Doppler results.

  11. Positron studies of the temperature-dependence of free volumes in Polydimethylsiloxane/poly(propylene oxide) urethane/urea membranes

    International Nuclear Information System (INIS)

    Free-volume parameters in polyurethane/urea membranes have been studied by positron annihilation lifetime and Doppler broadening measurements. The bi-soft segment membranes were obtained by varying the ratio of the structural constituents, polypropylene oxide and polydimethylsiloxane (PU/PDMS), with PDMS content from 25 to 75 wt%. The free-volume holes determined by PALS are correlated with gas permeation features. The phase separation of the various soft and hard segments in the membranes is mirrored in both lifetime and Doppler results

  12. TRPM2 channel opening in response to oxidative stress is dependent on activation of poly(ADP-ribose) polymerase

    OpenAIRE

    Fonfria, Elena; Marshall, Ian C B; Benham, Christopher D; Boyfield, Izzy; Brown, Jason D; Hill, Kerstin; Hughes, Jane P; Skaper, Stephen D.; McNulty, Shaun

    2004-01-01

    TRPM2 (melastatin-like transient receptor potential 2 channel) is a nonselective cation channel that is activated under conditions of oxidative stress leading to an increase in intracellular free Ca2+ concentration ([Ca2+]i) and cell death. We investigated the role of the DNA repair enzyme poly(ADP-ribose) polymerase (PARP) on hydrogen peroxide (H2O2)-mediated TRPM2 activation using a tetracycline-inducible TRPM2-expressing cell line.In whole-cell patch-clamp recordings, intracellular adenine...

  13. Enhanced strain-dependent electrical resistance of polyurethane composites with embedded oxidized multi-walled carbon nanotube networks

    Czech Academy of Sciences Publication Activity Database

    Benlikaya, R.; Slobodian, P.; Říha, Pavel

    2013-01-01

    Roč. 2013, Fall (2013). ISSN 1687-4110 Grant ostatní: GA MŠk(CZ) ED2.1.00/03.0111; GA MŠk(CZ) EE.2.3.20.0104; TBU Zlin(CZ) IGA/FT/2013/018 Institutional research plan: CEZ:AV0Z20600510 Institutional support: RVO:67985874 Keywords : carbon nanotubes * oxidation * strain sensor * gauge factor * polyurethane Subject RIV: BK - Fluid Dynamics Impact factor: 1.611, year: 2013 http://www.hindawi.com/journals/jnm/2013/327597/

  14. Telmisartan increases fatty acid oxidation in skeletal muscle through a peroxisome proliferator-activated receptor-[gamma] dependent pathway

    Czech Academy of Sciences Publication Activity Database

    Sugimoto, K.; Kazdová, L.; Qi, N.R.; Hyakukoku, M.; Křen, Vladimír; Šimáková, Miroslava; Zídek, Václav; Kurtz, T. W.; Pravenec, Michal

    2008-01-01

    Roč. 26, č. 6 (2008), s. 1209-1215. ISSN 0263-6352 R&D Projects: GA MŠk(CZ) 1M0520; GA MZd(CZ) NR8495; GA MZd NR9359; GA ČR(CZ) GA301/06/0028 Grant ostatní: -(XE) LSHG-CT-2005-019015; HHMI(US) 55005624; -(US) HL56028; -(US) HL63709 Institutional research plan: CEZ:AV0Z50110509 Source of funding: R - rámcový projekt EK ; N - neverejné zdroje Keywords : telmisartan * fatty acid oxidation * PPARgamma Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 5.132, year: 2008

  15. Stress depended changes in activityof gp red blood cells receptors and its correction by therahertz waves at nitric oxide frequency

    Directory of Open Access Journals (Sweden)

    Kirichuk V.F.

    2011-09-01

    Full Text Available The effect of electromagnetic radiation in the terahertz range frequencies of molecular spectrum of emission and absorption of nitric oxide 150.176–150.664 GHz for the restoration of the impaired carbohydrate component and functional activity glikoproteid receptors of erythrocytes of white rats in a state of acute imm obilization stress. Shown that exposure to electromagnetic waves at these frequencies is the normalization of the increased content of b-D-galactose in the carbohydrate component and the restoration of the impaired activity of the receptors glikoproteid erythrocytes

  16. Purification, molecular cloning, and expression of 2-hydroxyphytanoyl- CoA lyase, a peroxisomal thiamine pyrophosphate-dependent enzyme that catalyzes the carbon-carbon bond cleavage during à-oxidation of 3- methyl-branched fatty acids

    CERN Document Server

    Foulon, V; Croes, K; Waelkens, E

    1999-01-01

    Purification, molecular cloning, and expression of 2-hydroxyphytanoyl- CoA lyase, a peroxisomal thiamine pyrophosphate-dependent enzyme that catalyzes the carbon-carbon bond cleavage during à-oxidation of 3- methyl-branched fatty acids

  17. Dependence of precursor composition on patterning and morphology of sol–gel soft lithography based zinc zirconium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bera, Susanta; Pal, Moumita; Sarkar, Saswati [Sol–Gel Division, CSIR-Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, P.O. Jadavpur University, Kolkata 700 032 (India); Jana, Sunirmal, E-mail: sjana@cgcri.res.in [Sol–Gel Division, CSIR-Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, P.O. Jadavpur University, Kolkata 700 032 (India)

    2013-05-15

    Array-like surface patterned zinc zirconium oxide thin films (135–163 nm thickness) on soda lime silica glass substrate were prepared by sol–gel soft lithography from the precursor solutions (8 wt% equivalent metal oxides) having zinc acetate dihydrate (ZA) and zirconium oxychloride octahydrate (ZOO = 0–100 mol% w.r.t. ZA) in ethanol-2-butanol medium with acetylacetone. The ZOO concentration in solutions strongly influenced the pattern formation, crystallinity, morphology and optical property of the films. The films were crystalline in nature and enriched with only h-ZnO or a mixture of h-ZnO and c-ZrO{sub 2} below 55 mol% of ZOO content. On increasing ZOO concentration, a systematic change in morphology of h-ZnO nano/micro crystals from spherical to rod-shaped to sunflower-like particles was evident from electron microscopes (FESEM and TEM). Below 30 and above 65 mol% of ZOO, light surface patterns formed. However, the films from 30 to 65 mol% ZOO containing solutions evident distinct surface patterns with average periodicity, 1.5 μm and peak height, 20–70 nm by AFM measurements. The films were also characterized by UV–vis and FTIR spectral studies. Water and chloride contents from ZOO in the precursor solutions found to play a key role for generation of the film characteristics.

  18. Fatty acid-binding protein 4 impairs the insulin-dependent nitric oxide pathway in vascular endothelial cells

    Directory of Open Access Journals (Sweden)

    Aragonès Gemma

    2012-06-01

    Full Text Available Abstract Background Recent studies have shown that fatty acid-binding protein 4 (FABP4 plasma levels are associated with impaired endothelial function in type 2 diabetes (T2D. In this work, we analysed the effect of FABP4 on the insulin-mediated nitric oxide (NO production by endothelial cells in vitro. Methods In human umbilical vascular endothelial cells (HUVECs, we measured the effects of FABP4 on the insulin-mediated endothelial nitric oxide synthase (eNOS expression and activation and on NO production. We also explored the impact of exogenous FABP4 on the insulin-signalling pathway (insulin receptor substrate 1 (IRS1 and Akt. Results We found that eNOS expression and activation and NO production are significantly inhibited by exogenous FABP4 in HUVECs. FABP4 induced an alteration of the insulin-mediated eNOS pathway by inhibiting IRS1 and Akt activation. These results suggest that FABP4 induces endothelial dysfunction by inhibiting the activation of the insulin-signalling pathway resulting in decreased eNOS activation and NO production. Conclusion These findings provide a mechanistic linkage between FABP4 and impaired endothelial function in diabetes, which leads to an increased cardiovascular risk.

  19. Versatile redox chemistry complicates antioxidant capacity assessment: flavonoids as milieu-dependent anti- and pro-oxidants.

    Science.gov (United States)

    Chobot, Vladimir; Kubicova, Lenka; Bachmann, Gert; Hadacek, Franz

    2013-01-01

    Some antioxidants have been shown to possess additional pro-oxidant effects. Diverse methodologies exist for studying redox properties of synthetic and natural chemicals. The latter are substantial components of our diet. Exploration of their contribution to life-extending or -compromising effects is mandatory. Among reactive oxygen species (ROS), hydroxyl radical (•OH) is the most damaging species. Due to its short half-life, the assay has to contain a specific generation system. Plants synthesize flavonoids, phenolic compounds recognized as counter-agents to coronary heart disease. Their antioxidant activities are affected by their hydroxylation patterns. Moreover, in the plant, they mainly occur as glycosides. We chose three derivatives, quercetin, luteolin, and rutin, in attempts to explore their redox chemistry in contrasting hydrogen peroxide environments. Initial addition of hydrogen peroxide in high concentration or gradual development constituted a main factor affecting their redox chemical properties, especially in case of quercetin. Our study exemplifies that a combination of a chemical assay (deoxyribose degradation) with an electrochemical method (square-wave voltammetry) provides insightful data. The ambiguity of the tested flavonoids to act either as anti- or pro-oxidant may complicate categorization, but probably contributed to their evolution as components of a successful metabolic system that benefits both producer and consumer. PMID:23736691

  20. Versatile Redox Chemistry Complicates Antioxidant Capacity Assessment: Flavonoids as Milieu-Dependent Anti- and Pro-Oxidants

    Directory of Open Access Journals (Sweden)

    Gert Bachmann

    2013-06-01

    Full Text Available Some antioxidants have been shown to possess additional pro-oxidant effects. Diverse methodologies exist for studying redox properties of synthetic and natural chemicals. The latter are substantial components of our diet. Exploration of their contribution to life-extending or -compromising effects is mandatory. Among reactive oxygen species (ROS, hydroxyl radical (•OH is the most damaging species. Due to its short half-life, the assay has to contain a specific generation system. Plants synthesize flavonoids, phenolic compounds recognized as counter-agents to coronary heart disease. Their antioxidant activities are affected by their hydroxylation patterns. Moreover, in the plant, they mainly occur as glycosides. We chose three derivatives, quercetin, luteolin, and rutin, in attempts to explore their redox chemistry in contrasting hydrogen peroxide environments. Initial addition of hydrogen peroxide in high concentration or gradual development constituted a main factor affecting their redox chemical properties, especially in case of quercetin. Our study exemplifies that a combination of a chemical assay (deoxyribose degradation with an electrochemical method (square-wave voltammetry provides insightful data. The ambiguity of the tested flavonoids to act either as anti- or pro-oxidant may complicate categorization, but probably contributed to their evolution as components of a successful metabolic system that benefits both producer and consumer.

  1. [Age-dependent characteristics of oxidative stress formation in the liver of rats with hypothyroidism during intensive physical exercise].

    Science.gov (United States)

    Dzhazaérli, Mokhamad Salem; Davydov, V V

    2006-01-01

    The objective of the present experiment was to study free radical protein oxidation and lipid peroxidation in the liver of 1.5-month-old and 12-month-old rats with drug-induced hypothyroidism caused by exercises. The results of the present study suggest that intensive exercises are accompanied by an increase of intensity of free radical processes in the liver. Hypothyroidism and exercises do not greatly affect free radical processes in the liver of 12-month-old rats but result in additional stimulation of free radical oxidation in subcellular liver fractions of 1.5-month-old rats. An increase of free radical processes in the liver of 1.5-month-old rats with hypothyroidism caused by exercises is associated neither with changes in the first level antioxidant defense system enzymes function, nor with modulation of hepatocytes subcellular sensitivity to prooxidants. Such change is due largely to an increase of free radical production in the liver cells. PMID:17290792

  2. Temperature dependency of double material gate oxide (DMGO) symmetric dual-k spacer (SDS) wavy FinFET

    Science.gov (United States)

    Pradhan, K. P.; Priyanka; Sahu, P. K.

    2016-01-01

    Symmetric Dual-k Spacer (SDS) Trigate Wavy FinFET is a novel hybrid device that combines three significant and advanced technologies i.e., ultra-thin-body (UTB), FinFET, and symmetric spacer engineering on a single silicon on insulator (SOI) platform. This innovative architecture promises to enhance the device performance as compared to conventional FinFET without increasing the chip area. For the first time, we have incorporated two different dielectric materials (SiO2, and HfO2) as gate oxide to analyze the effect on various performance metrics of SDS wavy FinFET. This work evaluates the response of double material gate oxide (DMGO) on parameters like mobility, on current (Ion), transconductance (gm), transconductance generation factor (TGF), total gate capacitance (Cgg), and cutoff frequency (fT) in SDS wavy FinFET. This work also reveals the presence of biasing point i.e., zero temperature coefficient (ZTC) bias point. The ZTC bias point is that point where the device parameters become independent of temperature. The impact of operating temperature (T) on above said various performances are also subjected to extensive analysis. This further validates the reliability of DMGO-SDS FinFET and its application opportunities involved in modeling analog/RF circuits for a broad range of temperature applications. From extensive 3-D device simulation, we have determined that the inclusion of DMGO in SDS wavy FinFET is superior in performance.

  3. PRMT1 and PRMT4 Regulate Oxidative Stress-Induced Retinal Pigment Epithelial Cell Damage in SIRT1-Dependent and SIRT1-Independent Manners

    Directory of Open Access Journals (Sweden)

    Dong-Il Kim

    2015-01-01

    Full Text Available Oxidative stress-induced retinal pigment epithelial (RPE cell damage is involved in the progression of diabetic retinopathy. Arginine methylation catalyzed by protein arginine methyltransferases (PRMTs has emerged as an important histone modification involved in diverse diseases. Sirtuin (SIRT1 is a protein deacetylase implicated in the onset of metabolic diseases. Therefore, we examined the roles of type I PRMTs and their relationship with SIRT1 in human RPE cells under H2O2-induced oxidative stress. H2O2 treatment increased PRMT1 and PRMT4 expression but decreased SIRT1 expression. Similar to H2O2 treatment, PRMT1 or PRMT4 overexpression increased RPE cell damage. Moreover, the H2O2-induced RPE cell damage was attenuated by PRMT1 or PRMT4 knockdown and SIRT1 overexpression. In this study, we revealed that SIRT1 expression was regulated by PRMT1 but not by PRMT4. Finally, we found that PRMT1 and PRMT4 expression is increased in the RPE layer of streptozotocin-treated rats. Taken together, we demonstrated that oxidative stress induces apoptosis both via PRMT1 in a SIRT1-dependent manner and via PRMT4 in a SIRT1-independent manner. The inhibition of the expression of type I PRMTs, especially PRMT1 and PRMT4, and increased SIRT1 could be therapeutic approaches for diabetic retinopathy.

  4. Measurement of the electric-field and time dependence of the effective oxide-charge density of the Si-SiO2 system

    International Nuclear Information System (INIS)

    The surface radiation damage of SiO2 grown on high-ohmic n-type Si, as used for the fabrication of segmented silicon sensors, has been investigated. A circular p-MOSFET, biased in inversion at a field in the SiO2 of about 500 kV/cm, has been irradiated by X-rays up to a dose of about 17 kGy(SiO2) in different irradiation steps. Before and after each irradiation, the gate voltage has been cycled from inversion to accumulation conditions and back, and the threshold voltage of the MOSFET and the hole mobility at the Si-SiO2 interface determined. From the threshold voltage, the effective oxide-charge density is calculated. The measurement of the drain-source current during the irradiation allows the study of the change of the oxide-charge density during irradiation. Results on the dose dependence of the effective oxide-charge density, the charging-up and discharging of border traps when changing the gate voltage, and the hole mobility at the Si-SiO2 interface are presented

  5. The concentration dependence of Co sorption on corrosion product oxide layers on austenitic steel at 368 K (95 0C)

    International Nuclear Information System (INIS)

    The Co sorption on corrosion products of stainless steel is a chemisorption process of hydroxocation Co(OH)+. Its dependence upon concentration and pH may be described quantitatively by an absorption equation of Freundlich-type. A relation for the concentration of the monolayer was derived and the value calculated from measuring data. (author)

  6. Induction of time-dependent oxidative stress and related transcriptional effects of perfluorododecanoic acid in zebrafish liver

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yang [Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Datun Road, Beijing 100101 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100080 (China); Wang Jianshe; Wei Yanhong; Zhang Hongxia; Xu Muqi [Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Datun Road, Beijing 100101 (China); Dai Jiayin [Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Datun Road, Beijing 100101 (China)], E-mail: daijy@ioz.ac.cn

    2008-09-29

    The effects of acute perfluorododecanoic acid (PFDoA) exposure on the induction of oxidative stress and alteration of mitochondrial gene expression were studied in the livers of female zebrafish (Danio rerio). Female zebrafish were exposed to PFDoA via a single intraperitoneal injection (0, 20, 40, or 80 {mu}g PFDoA/g body weight) and were then sacrificed 48 h, 96 h, or seven days post-PFDoA administration. PFDoA-treated fish exhibited histopathological liver damage, including swollen hepatocytes, vacuolar degeneration, and nuclei pycnosis. Glutathione (GSH) content and catalase (CAT) activity decreased significantly at 48 h post-injection while superoxide dismutase (SOD) activity was initially decreased at 48 h post-injection but was then elevated by seven days post-injection. The activity of glutathione peroxidase (GPx) increased at 48 h and seven days compared to control fish, although the increased level at seven days post-injection was decreased compared to the level at 48 h post-injection. Lipid peroxidation levels were increased at seven days post-injection, while no apparent induction was observed at 48 h or 96 h post-injection. The mRNA expression of medium-chain fatty acid dehydrogenase (MCAD) was induced, while the transcriptional expression of liver fatty acid binding protein (L-FABP), peroxisome proliferating activating receptor {alpha} (PPAR{alpha}), carnitine palmitoyl-transferase I (CPT-I), uncoupling protein 2 (UCP-2), and Bcl-2 were significantly inhibited. Furthermore, the transcriptional expression of peroxisomal fatty acyl-CoA oxidase (ACOX), very long-chain acyl-CoA dehydrogenase (VLCAD), long-chain acyl-CoA dehydrogenase (LCAD) did not exhibit significant changes following PFDoA treatment. No significant changes were noted in the transcriptional expression of genes involved in mitochondrial respiratory chain and ATP synthesis, including cytochrome c oxidase subunit I (COXI), NADH dehydrogenase subunit I (NDI), and ATP synthase F0 subunit 6

  7. Induction of time-dependent oxidative stress and related transcriptional effects of perfluorododecanoic acid in zebrafish liver

    International Nuclear Information System (INIS)

    The effects of acute perfluorododecanoic acid (PFDoA) exposure on the induction of oxidative stress and alteration of mitochondrial gene expression were studied in the livers of female zebrafish (Danio rerio). Female zebrafish were exposed to PFDoA via a single intraperitoneal injection (0, 20, 40, or 80 μg PFDoA/g body weight) and were then sacrificed 48 h, 96 h, or seven days post-PFDoA administration. PFDoA-treated fish exhibited histopathological liver damage, including swollen hepatocytes, vacuolar degeneration, and nuclei pycnosis. Glutathione (GSH) content and catalase (CAT) activity decreased significantly at 48 h post-injection while superoxide dismutase (SOD) activity was initially decreased at 48 h post-injection but was then elevated by seven days post-injection. The activity of glutathione peroxidase (GPx) increased at 48 h and seven days compared to control fish, although the increased level at seven days post-injection was decreased compared to the level at 48 h post-injection. Lipid peroxidation levels were increased at seven days post-injection, while no apparent induction was observed at 48 h or 96 h post-injection. The mRNA expression of medium-chain fatty acid dehydrogenase (MCAD) was induced, while the transcriptional expression of liver fatty acid binding protein (L-FABP), peroxisome proliferating activating receptor α (PPARα), carnitine palmitoyl-transferase I (CPT-I), uncoupling protein 2 (UCP-2), and Bcl-2 were significantly inhibited. Furthermore, the transcriptional expression of peroxisomal fatty acyl-CoA oxidase (ACOX), very long-chain acyl-CoA dehydrogenase (VLCAD), long-chain acyl-CoA dehydrogenase (LCAD) did not exhibit significant changes following PFDoA treatment. No significant changes were noted in the transcriptional expression of genes involved in mitochondrial respiratory chain and ATP synthesis, including cytochrome c oxidase subunit I (COXI), NADH dehydrogenase subunit I (NDI), and ATP synthase F0 subunit 6 (ATPo6). These

  8. The dependence of dielectric parameters and electric conduction of composite on the base of polyethylene and iron oxide on radiation dose

    International Nuclear Information System (INIS)

    The radiation gamma-influence at 0-500 kGy doses on dielectric parameters and composite electric conduction on the base of high-density polyethylene and iron oxide radiated in air at room temperature is studied with the aim of modification of new class composite properties polymer-metal oxide. It is shown that different dependences have extreme character at (10 and 20 percent) α-Fe2O3 high concentrations. σ dependence of investigated samples also has extreme character and it is explained by accumulation of stabilized charge carriers in them. The experimental investigation of gamma-radiation influence on electrophysical properties of composite system of high-density polyethylene/α-Fe2O3 is the aim of the present paper. It is confirmed that electric conduction of polyethylene matrix is caused by charge carriers which appear at gamma -radiation and not by charges injected from electrodes. As a result of this the concentration density of deep traps on phase interface increases. Thus, the dose effects, like the influence of absorbed dose of gamma-radiation on electro-physical properties of previous radiation is caused not by spectrum change of molecular motions, but also accumulation in radiated material of stabilized charge cariers and less radical or molecular radiolysis products which act as trap centers

  9. Dependence of electrical and optical properties of sol-gel prepared undoped cadmium oxide thin films on annealing temperature

    International Nuclear Information System (INIS)

    The effect of the annealing temperature (T a) on the optical, electrical and structural properties of the undoped cadmium oxide (CdO) thin films obtained by the sol-gel method, using a simple precursor solution, was studied. All the CdO films annealed in the range from 200 to 450 deg. C are polycrystalline with (111) preferential orientation and present high optical transmission > 85% for wavelengths above 500 nm. The resistivity decreases as T a increases until it reaches a value of 6 x 10-4 Ω cm for T a 350 deg. C. For higher temperatures the resistivity experiences a slight increase. Images obtained by atomic force microscopy show an evident incremental change of the aggregate size (clusters of grains) as T a increases. The grain size also increases when T a increases as observed in data calculated from X-ray measurements

  10. Infrared spectroscopic studies on the cluster size dependence of charge carrier structure in nitrous oxide cluster anions

    Science.gov (United States)

    Thompson, Michael C.; Weber, J. Mathias

    2016-03-01

    We report infrared photodissociation spectra of nitrous oxide cluster anions of the form (N2O)nO- (n = 1-12) and (N2O)n- (n = 7-15) in the region 800-1600 cm-1. The charge carriers in these ions are NNO2- and O- for (N2O)nO- clusters with a solvation induced core ion switch, and N2O- for (N2O)n- clusters. The N-N and N-O stretching vibrations of N2O- (solvated by N2O) are reported for the first time, and they are found at (1595 ± 3) cm-1 and (894 ± 5) cm-1, respectively. We interpret our infrared spectra by comparison with the existing photoelectron spectroscopy data and with computational data in the framework of density functional theory.

  11. Structural properties of WO3 dependent of the annealing temperature deposited by hot-filament metal oxide deposition

    International Nuclear Information System (INIS)

    In this work presents a study of the effect of the annealing temperature on structural and optical properties of WO3 that has been grown by hot-filament metal oxide deposition. The chemical stoichiometry was determined by X-ray photoelectron spectroscopy. By X-ray diffraction obtained that the as-deposited WO3 films present mainly monoclinic crystalline phase. WO3 optical band gap energy can be varied from 2.92 to 3.15 eV obtained by transmittance measurements by annealing WO3 from 100 to 500 C. The Raman spectrum of the as-deposited WO3 film shows four intense peaks that are typical Raman peaks of crystalline WO3 (m-phase) that corresponds to the stretching vibrations of the bridging oxygen that are assigned to W-O stretching (υ) and W-O bending (δ) modes, respectively, which enhanced and increased their intensity with the annealing temperature. (Author)

  12. Spin-dependent transport properties of hetero-junction based on zigzag graphene nanoribbons with edge hydrogenation and oxidation

    Science.gov (United States)

    Cui, Li-ling; Long, Meng-qiu; Zhang, Xiao-jiao; Li, Xin-mei; Zhang, Dan; Yang, Bing-chu

    2016-02-01

    Using the non-equilibrium Green's function method and the spin-polarized density functional theory, we investigate the magnetism and spin resolved transport properties of hetero-structures based on zigzag graphene nanoribbons (ZGNRs) with edge hydrogenation (H) and oxidation (O). It is found that a perfect spin filtering effect can be realized on O-ZGNR-H/H-ZGNR-H in both parallel and anti-parallel spin configurations. Interestingly, an excellent dual spin filtering behavior can be obtained on O-ZGNR-H/H2-ZGNR-H, which is independent of the width of the nanoribbon. Our results indicate that the hetero-structure holds promise for spintronic devices in future.

  13. Mechanism of phytoestrogen puerarin-mediated cytoprotection following oxidative injury: Estrogen receptor-dependent up-regulation of PI3K/Akt and HO-1

    International Nuclear Information System (INIS)

    Phytoestrogens are polyphenolic non-steroidal plant compounds with estrogen-like biological activity. The phytoestrogen puerarin, the main isoflavone glycoside found in the root of Pueraria lobata, has been used for various medicinal purposes in traditional Chinese medicines for thousands of years. Recent studies have indicated that the estrogen receptor (ER), through interaction with p85, regulates phosphoinositide 3-kinase (PI3K) activity, revealing a physiologic, non-nuclear function of ER that may be relevant in cytoprotection. In this study, we demonstrate that the phytoestrogen puerarin inhibits tert-butyl hydroperoxide (t-BHP)-induced oxidative injury via an ER-dependent Gβ1/PI3K/Akt and heme oxygenase-1 (HO-1) pathway. Pretreatment of Hepa1c1c7 and HepG2 cells with puerarin significantly reduced t-BHP-induced caspase-3 activation and subsequent cell death. Also, puerarin up-regulated HO-1 expression and this expression conferred cytoprotection against oxidative injury induced by t-BHP. Moreover, puerarin induced Nrf2 nuclear translocation, which is upstream of puerarin-induced HO-1 expression, and PI3K activation, a pathway that is involved in induced Nrf2 nuclear translocation, HO-1 expression and cytoprotection. Puerarin-induced up-regulation of HO-1 and cytoprotection against t-BHP were abolished by silencing Nrf2 expression with specific siRNA. Also, puerarin-mediated increases in PI3K activation and HO-1 induction were reversed by co-treatment with ICI 182,780 and pertussis toxin. Taken together, these results suggest that puerarin augments cellular antioxidant defense capacity through ER-dependent HO-1 induction via the Gβ1/PI3K/Akt-Nrf2 signaling pathway, thereby protecting cells from oxidative stress

  14. Temperature dependence of frequency dispersion in III–V metal-oxide-semiconductor C-V and the capture/emission process of border traps

    International Nuclear Information System (INIS)

    This paper presents a detailed investigation of the temperature dependence of frequency dispersion observed in capacitance-voltage (C-V) measurements of III-V metal-oxide-semiconductor (MOS) devices. The dispersion in the accumulation region of the capacitance data is found to change from 4%–9% (per decade frequency) to ∼0% when the temperature is reduced from 300 K to 4 K in a wide range of MOS capacitors with different gate dielectrics and III-V substrates. We show that such significant temperature dependence of C-V frequency dispersion cannot be due to the temperature dependence of channel electrostatics, i.e., carrier density and surface potential. We also show that the temperature dependence of frequency dispersion, and hence, the capture/emission process of border traps can be modeled by a combination of tunneling and a “temperature-activated” process described by a non-radiative multi-phonon model, instead of a widely believed single-step elastic tunneling process

  15. A study of the influence of temperature dependent thermal conductivity on static power coefficient of PFBR oxide core using a variational one dimensional finite element methodology

    International Nuclear Information System (INIS)

    A study has been carried out to examine the influence of temperature dependent thermal conductivity on the static power coefficient of reactivity for Prototype Fast Breeder Reactor (PFBR) oxide core. Change in core material density, core boundary movement, core 1 to core 2 fuel movement, Doppler coefficient and spacer pad expansion effects due to power rise, have been considered for calculating the power coefficient. For temperature rise calculations for the case of temperature dependent thermal conductivity of fuel, one dimensional finite element method based on variational approach has been applied. It is observed that for the case of temperature dependent thermal conductivity, average temperature of the fuel pin in the middle portion is higher but it is lower in the bottom and upper part of the pin than the case of temperature independent thermal conductivity. Because of this opposing effect, over all static power coefficient is influenced, marginally though it is higher for the case when thermal conductivity is temperature dependent. The paper provides the details of the results. (author). 2 refs., 2 tabs., 1 fig

  16. Temperature dependence of frequency dispersion in III–V metal-oxide-semiconductor C-V and the capture/emission process of border traps

    Energy Technology Data Exchange (ETDEWEB)

    Vais, Abhitosh, E-mail: Abhitosh.Vais@imec.be; Martens, Koen; DeMeyer, Kristin [Department of Electrical Engineering, KU Leuven, B-3000 Leuven (Belgium); IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Lin, Han-Chung; Ivanov, Tsvetan; Collaert, Nadine; Thean, Aaron [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Dou, Chunmeng [Frontier Research Center, Tokyo Institute of Technology, Yokohama 226-8502 (Japan); Xie, Qi; Maes, Jan [ASM International, B-3001 Leuven (Belgium); Tang, Fu; Givens, Michael [ASM International, Phoenix, Arizona 85034-7200 (United States); Raskin, Jean-Pierre [Institute of Information and Communication Technologies, Electronics and Applied Mathematics, Universiteé Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium)

    2015-08-03

    This paper presents a detailed investigation of the temperature dependence of frequency dispersion observed in capacitance-voltage (C-V) measurements of III-V metal-oxide-semiconductor (MOS) devices. The dispersion in the accumulation region of the capacitance data is found to change from 4%–9% (per decade frequency) to ∼0% when the temperature is reduced from 300 K to 4 K in a wide range of MOS capacitors with different gate dielectrics and III-V substrates. We show that such significant temperature dependence of C-V frequency dispersion cannot be due to the temperature dependence of channel electrostatics, i.e., carrier density and surface potential. We also show that the temperature dependence of frequency dispersion, and hence, the capture/emission process of border traps can be modeled by a combination of tunneling and a “temperature-activated” process described by a non-radiative multi-phonon model, instead of a widely believed single-step elastic tunneling process.

  17. Quantitative Profiling of Protein S-Glutathionylation Reveals Redox-Dependent Regulation of Macrophage Function During Nanoparticle-Induced Oxidative Stress

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Jicheng; Kodali, Vamsi K.; Gaffrey, Matthew J.; Guo, Jia; Chu, Rosalie K.; Camp, David G.; Smith, Richard D.; Thrall, Brian D.; Qian, Weijun

    2015-12-23

    Engineered nanoparticles (ENPs) are emerging functional materials increasingly utilized for commercial and medical applications. Due to the potential hazard effects of ENPs to human health, it is significant to assess and understand the underlying mechanisms of nanotoxicity. Herein, we investigate protein S-glutathionylation (SSG) as an underlying regulatory mechanism for ENP-induced oxidative stress in macrophages by applying a recently developed quantitative redox proteomics approach for site-specific measurements of SSG. Three high-volume production ENPs (SiO2, Fe3O4 and CoO) were selected as representative ENPs with low, moderate, and high reactive oxygen species (ROS) activity, respectively. Among these nanoparticles, we observe that CoO led to the most significant dose-dependent oxidative stress and increase of protein SSG modifications in macrophages. Our site-specific SSG changes highlighted a broad set of redox sensitive proteins and their specific Cys residues potentially implicated in stress response. Functional analysis revealed that the most significantly enriched functional categories for SSG-modified proteins were stress response, cellular structure change, and cell death or survival. Moreover, ENPs-induce oxidative stress levels (CoO > Fe3O4 > SiO2) were found to correlate well with the levels of impairment of macrophage phagocytic activity and the overall degrees of increases in SSG. RNA silencing knockdown experiment of glutaredoxin 1 (Grx1) also led to a decreased phagocytic activity in macrophages, which suggested a regulatory role of SSG in phagocytosis. Together, the results provided valuable insights of protein SSG as a potential regulatory mechanism in response to nanomaterial-induced oxidative stress and immunity dysfunction.

  18. A factorial randomized controlled trial to evaluate the effect of micronutrients supplementation and regular aerobic exercise on maternal endothelium-dependent vasodilatation and oxidative stress of the newborn

    Directory of Open Access Journals (Sweden)

    Girón Sandra

    2011-02-01

    Full Text Available Abstract Background Many studies have suggested a relationship between metabolic abnormalities and impaired fetal growth with the development of non-transmissible chronic diseases in the adulthood. Moreover, it has been proposed that maternal factors such as endothelial function and oxidative stress are key mechanisms of both fetal metabolic alterations and subsequent development of non-transmissible chronic diseases. The objective of this project is to evaluate the effect of micronutrient supplementation and regular aerobic exercise on endothelium-dependent vasodilation maternal and stress oxidative of the newborn. Methods and design 320 pregnant women attending to usual prenatal care in Cali, Colombia will be included in a factorial randomized controlled trial. Women will be assigned to the following intervention groups: 1. Control group: usual prenatal care (PC and placebo (maltodextrine. 2. Exercise group: PC, placebo and aerobic physical exercise. 3. Micronutrients group: PC and a micronutrients capsule consisting of zinc (30 mg, selenium (70 μg, vitamin A (400 μg, alphatocopherol (30 mg, vitamin C (200 mg, and niacin (100 mg. 4. Combined interventions Group: PC, supplementation of micronutrients, and aerobic physical exercise. Anthropometric measures will be taken at the start and at the end of the interventions. Discussion Since in previous studies has been showed that the maternal endothelial function and oxidative stress are related to oxidative stress of the newborn, this study proposes that complementation with micronutrients during pregnancy and/or regular physical exercise can be an early and innovative alternative to strengthen the prevention of chronic diseases in the population. Trial registration NCT00872365.

  19. Use-dependent loss of active sympathetic neurogenic vasodilation after nitric oxide synthase inhibition in conscious rats. Evidence for the presence of preformed stores of nitric oxide-containing factors

    Science.gov (United States)

    Davisson, R. L.; Shaffer, R. A.; Johnson, A. K.; Lewis, S. J.

    1996-01-01

    In this study, we examined whether air-jet stress-induced active sympathetic hindlimb vasodilation in conscious rats involves the release of preformed stores of nitric oxide-containing factors. We determined the effects of repeated episodes of air-jet stress (six episodes given 5 minutes apart) on mean arterial pressure and vascular resistances in the mesenteric bed and intact and sympathetically denervated hindlimb beds of conscious rats treated with saline or the nitric oxide synthesis inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 25 mumol/kg IV). In saline-treated rats, air-jet stress produced alerting behavior, minor changes in blood pressure, pronounced mesenteric vaso-constriction, and immediate and marked vasodilation in the sympathetically intact hindlimb but a minor vasodilation in the sympathetically denervated hindlimb. Each air-jet stress produced virtually identical responses. In L-NAME-treated rats, the first air-jet stress produced vasodilator responses in the sympathetically intact and sympathetically denervated hindlimbs that were similar to those in the saline-treated rats. However, each subsequent air-jet stress produced progressively smaller vasodilator responses in the sympathetically intact but not the sympathetically denervated hindlimb. There was no loss of air-jet stress-induced alerting behavior or mesenteric vasoconstriction, suggesting that L-NAME did not interfere with the central processing of the air-jet or the resultant changes in autonomic nerve activity. The progressive diminution of air-jet stress-induced vasodilation in the intact hindlimb of L-NAME-treated rats may be due to the use-dependent depletion of preformed stores of nitric oxide-containing factors that cannot be replenished in the absence of nitric oxide synthesis.

  20. Rosiglitazone activation of PPARγ-dependent pathways is neuroprotective in human neural stem cells against amyloid-beta-induced mitochondrial dysfunction and oxidative stress.

    Science.gov (United States)

    Chiang, Ming-Chang; Nicol, Christopher J; Cheng, Yi-Chuan; Lin, Kuan-Hung; Yen, Chia-Hui; Lin, Chien-Hung

    2016-04-01

    Neuronal cell impairment, such as that induced by amyloid-beta (Aβ) protein, is a process with limited therapeutic interventions and often leads to long-term neurodegeneration common in disorders such as Alzheimer's disease. Interestingly, peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated nuclear receptor whose ligands control many physiological and pathologic processes, and may be neuroprotective. We hypothesized that rosiglitazone, a PPARγ agonist, would prevent Aβ-mediated effects in human neural stem cells (hNSCs). Here, we show that rosiglitazone reverses, via PPARγ-dependent downregulation of caspase 3 and 9 activity, the Aβ-mediated decreases in hNSC cell viability. In addition, Aβ decreases hNSC messenger RNA (mRNA) levels of 2 neuroprotective factors (Bcl-2 and CREB), but co-treatment with rosiglitazone significantly rescues these effects. Rosiglitazone co-treated hNSCs also showed significantly increased mitochondrial function (reflected by levels of adenosine triphosphate and Mit mass), and PPARγ-dependent mRNA upregulation of PGC1α and mitochondrial genes (nuclear respiratory factor-1 and Tfam). Furthermore, hNSCs co-treated with rosiglitazone were significantly rescued from Aβ-induced oxidative stress and correlates with reversal of the Aβ-induced mRNA decrease in oxidative defense genes (superoxide dismutase 1, superoxide dismutase 2, and glutathione peroxidase 1). Taken together, these novel findings show that rosiglitazone-induced activation of PPARγ-dependent signaling rescues Aβ-mediated toxicity in hNSCs and provide evidence supporting a neuroprotective role for PPARγ activating drugs in Aβ-related diseases such as Alzheimer's disease. PMID:26973118

  1. Nitric oxide mediates the fungal elicitor-induced puerarin biosynthesis in Pueraria thomsonii Benth. suspension cells through a salicylic acid (SA)-dependent and a jasmonic acid (JA)-dependent signal pathway

    Institute of Scientific and Technical Information of China (English)

    XU Maojun; DONG Jufang; ZHU Muyuan

    2006-01-01

    Nitric oxide (NO) has emerged as a key signaling molecule in plant secondary metabolite biosynthesis recently. In order to investigate the molecular basis of NO signaling in elicitor-induced secondary metabolite biosynthesis of plant cells, we determined the contents of NO, salicylic acid (SA), jasmonic acid (JA), and puerarin in Pueraria thomsonii Benth. suspension cells treated with the elicitors prepared from cell walls of Penicillium citrinum. The results showed that the fungal elicitor induced NO burst, SA accumulation and puerarin production of P. thomsonii Benth. cells. The elicitor-induced SA accumulation and puerarin production was suppressed by nitric oxide specific scavenger cPITO, indicating that NO was essential for elicitor-induced SA and puerarin biosynthesis in P. thomsonii Benth. cells. In transgenic NahG P. thomsonii Benth. cells, the fungal elicitor also induced puerarin biosynthesis, NO burst, and JA accumulation, though the SA biosynthesis was impaired. The elicitor-induced JA accumulation in transgenic cells was blocked by cPITO, which suggested that JA acted downstream of NO and its biosynthesis was controlled by NO. External application of NO via its donor sodium nitroprusside (SNP) enhanced puerarin biosynthesis in transgenic NahG P. thomsonii Benth. cells, and the NO-triggered puerarin biosynthesis was suppressed by JA inhibitors IBU and NDGA, which indicated that NO induced puerarin production through a JA-dependent signal pathway in the transgenic cells. Exogenous application of SA suppressed the elicitor-induced JA biosynthesis and reversed the inhibition of IBU and NDGA on elicitor-induced puerarin accumulation in transgenic cells, which indicated that SA inhibited JA biosynthesis in the cells and that SA might be used as a substitute for JA to mediate the elicitor- and NO-induced puerarin biosynthesis. It was, therefore, concluded that NO might mediate the elicitor-induced puerarin biosynthesis through SA- and JA-dependent signal

  2. Oxidative stress-dependent sphingosine kinase-1 inhibition mediates monoamine oxidase A-associated cardiac cell apoptosis.

    Science.gov (United States)

    Pchejetski, Dimitri; Kunduzova, Oxana; Dayon, Audrey; Calise, Denis; Seguelas, Marie-Hélène; Leducq, Nathalie; Seif, Isabelle; Parini, Angelo; Cuvillier, Olivier

    2007-01-01

    The mitochondrial enzyme monoamine oxidase (MAO), its isoform MAO-A, plays a major role in reactive oxygen species-dependent cardiomyocyte apoptosis and postischemic cardiac damage. In the current study, we investigated whether sphingolipid metabolism can account for mediating MAO-A- and reactive oxygen species-dependent cardiomyocyte apoptosis. In H9c2 cardiomyoblasts, MAO-A-dependent reactive oxygen species generation led to mitochondria-mediated apoptosis, along with sphingosine kinase-1 (SphK1) inhibition. These phenomena were associated with generation of proapoptotic ceramide and decrease in prosurvival sphingosine 1-phosphate. These events were mimicked by inhibition of SphK1 with either pharmacological inhibitor or small interfering RNA, as well as by extracellular addition of C(2)-ceramide or H(2)O(2). In contrast, enforced expression of SphK1 protected H9c2 cells from serotonin- or H(2)O(2)-induced apoptosis. Analysis of cardiac tissues from wild-type mice subjected to ischemia/reperfusion revealed significant upregulation of ceramide and inhibition of SphK1. It is noteworthy that SphK1 inhibition, ceramide accumulation, and concomitantly infarct size and cardiomyocyte apoptosis were significantly decreased in MAO-A-deficient animals. In conclusion, we show for the first time that the upregulation of ceramide/sphingosine 1-phosphate ratio is a critical event in MAO-A-mediated cardiac cell apoptosis. In addition, we provide the first evidence linking generation of reactive oxygen species with SphK1 inhibition. Finally, we propose sphingolipid metabolites as key mediators of postischemic/reperfusion cardiac injury. PMID:17158340

  3. Hepatic calcium efflux during cytochrome P-450-dependent drug oxidations at the endoplasmic reticulum in intact liver.

    OpenAIRE

    Sies, H; P. Graf; Estrela, J M

    1981-01-01

    During metabolism of (type I) drugs by cytochrome P-450-dependent monooxygenase of the endoplasmic reticulum, the NADPH/NADP+ ratio in rat liver selectively decreases to approximately one-half of the control values, whereas the NADH/NAD+ ratio remains practically unaffected [Sies, H. & Brauser, B. (1970) Eur. J. Biochem. 15, 521-540]. In view of the observations with isolated mitochondria [Lehninger, A. L., Vercesi, A. & Bababunmi, E. A. (1978) Proc. Natl. Acad. Sci. USA 75, 1690-1694] of sti...

  4. Enhancement of Photo-Oxidation Activities Depending on Structural Distortion of Fe-Doped TiO2 Nanoparticles.

    Science.gov (United States)

    Kim, Yeonwoo; Yang, Sena; Jeon, Eun Hee; Baik, Jaeyoon; Kim, Namdong; Kim, Hyun Sung; Lee, Hangil

    2016-12-01

    To design a high-performance photocatalytic system with TiO2, it is necessary to reduce the bandgap and enhance the absorption efficiency. The reduction of the bandgap to the visible range was investigated with reference to the surface distortion of anatase TiO2 nanoparticles induced by varying Fe doping concentrations. Fe-doped TiO2 nanoparticles (Fe@TiO2) were synthesized by a hydrothermal method and analyzed by various surface analysis techniques such as transmission electron microscopy, Raman spectroscopy, X-ray diffraction, scanning transmission X-ray microscopy, and high-resolution photoemission spectroscopy. We observed that Fe doping over 5 wt.% gave rise to a distorted structure, i.e., Fe2Ti3O9, indicating numerous Ti(3+) and oxygen-vacancy sites. The Ti(3+) sites act as electron trap sites to deliver the electron to O2 as well as introduce the dopant level inside the bandgap, resulting in a significant increase in the photocatalytic oxidation reaction of thiol (-SH) of 2-aminothiophenol to sulfonic acid (-SO3H) under ultraviolet and visible light illumination. PMID:26822520

  5. Temperature-dependent analysis of conduction mechanism of leakage current in thermally grown oxide on 4H-SiC

    International Nuclear Information System (INIS)

    The conduction mechanism of the leakage current of a thermally grown oxide on 4H silicon carbide (4H-SiC) was investigated. The dominant carriers of the leakage current were found to be electrons by the carrier-separation current-voltage method. The current-voltage and capacitance-voltage characteristics, which were measured over a wide temperature range, revealed that the leakage current in SiO2/4H-SiC on the Si-face can be explained as the sum of the Fowler-Nordheim (FN) tunneling and Poole-Frenkel (PF) emission leakage currents. A rigorous FN analysis provided the true barrier height for the SiO2/4H-SiC interface. On the basis of Arrhenius plots of the PF current separated from the total leakage current, the existence of carbon-related defects and/or oxygen vacancy defects was suggested in thermally grown SiO2 films on the Si-face of 4H-SiC

  6. Temperature-dependent analysis of conduction mechanism of leakage current in thermally grown oxide on 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Sometani, Mitsuru; Takei, Manabu [Advanced Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, 305-8568 Ibaraki (Japan); Fuji Electric Co. Ltd., 1 Fuji-machi, Hino, 191-8502 Tokyo (Japan); Okamoto, Dai; Harada, Shinsuke; Ishimori, Hitoshi; Takasu, Shinji; Hatakeyama, Tetsuo; Yonezawa, Yoshiyuki; Fukuda, Kenji; Okumura, Hajime [Advanced Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, 305-8568 Ibaraki (Japan)

    2015-01-14

    The conduction mechanism of the leakage current of a thermally grown oxide on 4H silicon carbide (4H-SiC) was investigated. The dominant carriers of the leakage current were found to be electrons by the carrier-separation current-voltage method. The current-voltage and capacitance-voltage characteristics, which were measured over a wide temperature range, revealed that the leakage current in SiO{sub 2}/4H-SiC on the Si-face can be explained as the sum of the Fowler-Nordheim (FN) tunneling and Poole-Frenkel (PF) emission leakage currents. A rigorous FN analysis provided the true barrier height for the SiO{sub 2}/4H-SiC interface. On the basis of Arrhenius plots of the PF current separated from the total leakage current, the existence of carbon-related defects and/or oxygen vacancy defects was suggested in thermally grown SiO{sub 2} films on the Si-face of 4H-SiC.

  7. Leaf Age-Dependent Photoprotective and Antioxidative Response Mechanisms to Paraquat-Induced Oxidative Stress in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Julietta Moustaka

    2015-06-01

    Full Text Available Exposure of Arabidopsis thaliana young and mature leaves to the herbicide paraquat (Pq resulted in a localized increase of hydrogen peroxide (H2O2 in the leaf veins and the neighboring mesophyll cells, but this increase was not similar in the two leaf types. Increased H2O2 production was concomitant with closed reaction centers (qP. Thirty min after Pq exposure despite the induction of the photoprotective mechanism of non-photochemical quenching (NPQ in mature leaves, H2O2 production was lower in young leaves mainly due to the higher increase activity of ascorbate peroxidase (APX. Later, 60 min after Pq exposure, the total antioxidant capacity of young leaves was not sufficient to scavenge the excess reactive oxygen species (ROS that were formed, and thus, a higher H2O2 accumulation in young leaves occurred. The energy allocation of absorbed light in photosystem II (PSII suggests the existence of a differential photoprotective regulatory mechanism in the two leaf types to the time-course Pq exposure accompanied by differential antioxidant protection mechanisms. It is concluded that tolerance to Pq-induced oxidative stress is related to the redox state of quinone A (QA.

  8. Structural properties of WO{sub 3} dependent of the annealing temperature deposited by hot-filament metal oxide deposition

    Energy Technology Data Exchange (ETDEWEB)

    Flores M, J. E. [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias de la Electronica, Av. San Claudio y 18 Sur, Ciudad Universitaria, Col. Jardines de San Manuel, 72570 Puebla (Mexico); Diaz R, J. [IPN, Centro de Investigacion en Biotecnologia Aplicada, Ex-Hacienda de San Molino Km 1.5 Tepetitla, 90700 Tlaxcala (Mexico); Balderas L, J. A., E-mail: eflores@ece.buap.mx [IPN, Unidad Profesional Interdisciplinaria de Biotecnologia, Av. Acueducto s/n, Col. Barrio la Laguna, 07340 Mexico D. F. (Mexico)

    2012-07-01

    In this work presents a study of the effect of the annealing temperature on structural and optical properties of WO{sub 3} that has been grown by hot-filament metal oxide deposition. The chemical stoichiometry was determined by X-ray photoelectron spectroscopy. By X-ray diffraction obtained that the as-deposited WO{sub 3} films present mainly monoclinic crystalline phase. WO{sub 3} optical band gap energy can be varied from 2.92 to 3.15 eV obtained by transmittance measurements by annealing WO{sub 3} from 100 to 500 C. The Raman spectrum of the as-deposited WO{sub 3} film shows four intense peaks that are typical Raman peaks of crystalline WO{sub 3} (m-phase) that corresponds to the stretching vibrations of the bridging oxygen that are assigned to W-O stretching ({upsilon}) and W-O bending ({delta}) modes, respectively, which enhanced and increased their intensity with the annealing temperature. (Author)

  9. Nitric oxide-induced eosinophil apoptosis is dependent on mitochondrial permeability transition (mPT, JNK and oxidative stress: apoptosis is preceded but not mediated by early mPT-dependent JNK activation

    Directory of Open Access Journals (Sweden)

    Ilmarinen-Salo Pinja

    2012-08-01

    Full Text Available Abstract Background Eosinophils are critically involved in the pathogenesis of asthma. Nitric oxide (NO is produced in high amounts in asthmatic lungs and has an important role as a regulator of lung inflammation. NO was previously shown to induce eosinophil apoptosis mediated via c-jun N-terminal kinase (JNK and caspases. Our aim was to clarify the cascade of events leading to NO-induced apoptosis in granulocyte macrophage-colony stimulating factor (GM-CSF-treated human eosinophils concentrating on the role of mitochondria, reactive oxygen species (ROS and JNK. Methods Apoptosis was determined by flow cytometric analysis of relative DNA content, by Annexin-V labelling and/or morphological analysis. Immunoblotting was used to study phospho-JNK (pJNK expression. Mitochondrial membrane potential was assessed by JC-1-staining and mitochondrial permeability transition (mPT by loading cells with calcein acetoxymethyl ester (AM and CoCl2 after which flow cytometric analysis was conducted. Statistical significance was calculated by repeated measures analysis of variance (ANOVA or paired t-test. Results NO-donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP induced late apoptosis in GM-CSF-treated eosinophils. SNAP-induced apoptosis was suppressed by inhibitor of mPT bongkrekic acid (BA, inhibitor of JNK SP600125 and superoxide dismutase-mimetic AEOL 10150. Treatment with SNAP led to late loss of mitochondrial membrane potential. Additionally, we found that SNAP induces early partial mPT (1 h that was followed by a strong increase in pJNK levels (2 h. Both events were prevented by BA. However, these events were not related to apoptosis because SNAP-induced apoptosis was prevented as efficiently when BA was added 16 h after SNAP. In addition to the early and strong rise, pJNK levels were less prominently increased at 20–30 h. Conclusions Here we demonstrated that NO-induced eosinophil apoptosis is mediated via ROS, JNK and late mPT. Additionally

  10. Estradiol coupling to human monocyte nitric oxide release is dependent on intracellular calcium transients: evidence for an estrogen surface receptor.

    Science.gov (United States)

    Stefano, G B; Prevot, V; Beauvillain, J C; Fimiani, C; Welters, I; Cadet, P; Breton, C; Pestel, J; Salzet, M; Bilfinger, T V

    1999-10-01

    We tested the hypothesis that estrogen acutely stimulates constitutive NO synthase (cNOS) activity in human peripheral monocytes by acting on an estrogen surface receptor. NO release was measured in real time with an amperometric probe. 17beta-estradiol exposure to monocytes stimulated NO release within seconds in a concentration-dependent manner, whereas 17alpha-estradiol had no effect. 17beta-estradiol conjugated to BSA (E2-BSA) also stimulated NO release, suggesting mediation by a membrane surface receptor. Tamoxifen, an estrogen receptor inhibitor, antagonized the action of both 17beta-estradiol and E2-BSA, whereas ICI 182,780, a selective inhibitor of the nuclear estrogen receptor, had no effect. We further showed, using a dual emission microfluorometry in a calcium-free medium, that the 17beta-estradiol-stimulated release of monocyte NO was dependent on the initial stimulation of intracellular calcium transients in a tamoxifen-sensitive process. Leeching out the intracellular calcium stores abolished the effect of 17beta-estradiol on NO release. RT-PCR analysis of RNA obtained from the cells revealed a strong estrogen receptor-alpha amplification signal and a weak beta signal. Taken together, a physiological dose of estrogen acutely stimulates NO release from human monocytes via the activation of an estrogen surface receptor that is coupled to increases in intracellular calcium. PMID:10490972

  11. Insulin receptor substrate-1 prevents autophagy-dependent cell death caused by oxidative stress in mouse NIH/3T3 cells

    Directory of Open Access Journals (Sweden)

    Chan Shih-Hung

    2012-07-01

    -induced autophagy and cell death. Conclusion Our results suggest that overexpression of IRS-1 promotes cells growth, inhibits basal autophagy, reduces oxidative stress-induced autophagy, and diminishes oxidative stress-mediated autophagy-dependent cell death. ROS-mediated autophagy may occur via inhibition of IRS-1/phosphatidylinositol 3-kinase/mTOR signaling. Our data afford a plausible explanation for IRS-1 involvement in tumor initiation and progression.

  12. Relaxation to bradykinin in bovine pulmonary supernumerary arteries can be mediated by both a nitric oxide-dependent and -independent mechanism

    Science.gov (United States)

    Tracey, A; Bunton, D; Irvine, J; MacDonald, A; Shaw, A M

    2002-01-01

    The aim of the present study was to determine the relative contribution of prostanoids, nitric oxide and K+ channels in the bradykinin-induced relaxation of bovine pulmonary supernumerary arteries. In endothelium-intact, but not denuded rings, bradykinin produced a concentration-dependent relaxation (pEC50, 9.6±0.1), which was unaffected by the cyclo-oxygenase inhibitor indomethacin. The nitric oxide scavenger hydroxocobalamin (200 μM, pEC50, 8.5±0.2) and the nitric oxide synthase inhibitor L-NAME (100 μM, pEC50, 8.9±0.1) and the combination of L-NAME and hydroxocobalamin (pEC50, 8.1±0.2) produced rightward shifts in the bradykinin concentration response curve. The guanylyl cyclase inhibitor ODQ (10 μM, pEC50, 9.6±0.4) did not affect the response to bradykinin. Elevating the extracellular [K+] to 30 mM did not affect the response to bradykinin but abolished the response when ODQ or L-NAME was present. The K+ channel blocker apamin (100 nM), combined with charybdotoxin (100 nM), produced a small reduction in the maximum response to bradykinin but they abolished the response to bradykinin when ODQ, L-NAME or hydroxocobalamin were present. Apamin (100 nM) combined with iberiotoxin (100 nM) also reduced the response to bradykinin in the presence of hydroxocobalamin or L-NAME. The concentration response curve for sodium nitroprusside-induced relaxation was abolished by ODQ (10 μM) and shifted to the right by apamin and charybdotoxin. These studies suggest that in bovine pulmonary supernumerary arteries bradykinin can stimulate the formation of nitric oxide and activate an EDHF-like mechanism and that either of these pathways alone can mediate the bradykinin-induced relaxation. In addition nitric oxide, acting through guanylyl cyclase, can activate an apamin/charbydotoxin-sensitive K+ channel in this tissue. PMID:12359636

  13. Gate length and temperature dependence of negative differential transconductance in silicon quantum well metal-oxide-semiconductor field-effect transistors

    International Nuclear Information System (INIS)

    Introducing quantum transport into silicon transistors in a manner compatible with industrial fabrication has the potential to transform the performance horizons of large scale integrated silicon devices and circuits. Explicit quantum transport as evidenced by negative differential transconductances (NDTCs) has been observed in a set of quantum well (QW) transistors fabricated using industrial silicon complementary metal-oxide-semiconductor processing. Detailed gate length and temperature dependence characteristics of the NDTCs in these devices have been measured. The QW potential was formed via lateral ion implantation doping on a commercial 45 nm technology node process line, and measurements of the transfer characteristics show NDTCs up to room temperature. Gate length dependence of NDTCs shows a correlation of the interface channel length with the number of NDTCs formed as well as with the gate voltage (VG) spacing between NDTCs. The VG spacing between multiple NDTCs suggests a quasi-parabolic QW potential profile. The temperature dependence is consistent with partial freeze-out of carrier concentration against a degenerately doped background

  14. Efficiency, specificity and DNA polymerase-dependence of translesion replication across the oxidative DNA lesion 8-oxoguanine in human cells

    International Nuclear Information System (INIS)

    The oxidation product of guanine, 8-oxoguanine, is a major lesion formed in DNA by intracellular metabolism, ionizing radiation, and tobacco smoke. Using a recently developed method for the quantitative analysis of translesion replication, we have studied the bypass of 8-oxoguanine in vivo by transfecting human cells with a gapped plasmid carrying a site-specific 8-oxoguanine in the ssDNA region. The efficiency of bypass in the human large-cell lung carcinoma cell line H1299 was 80%, and it was similar when assayed in the presence of aphidicolin, an inhibitor of DNA polymerases α, δ and ε. A similar extent of bypass was observed also in XP-V cells, defective in pol η, both in the absence and presence of aphidicolin. DNA sequence analysis indicated that the major nucleotide inserted opposite the 8-oxoguanine was the correct nucleotide C, both in H1299 cells (81%) and in XP-V cells (77%). The major mutagenic event was the insertion of an A, both in H1299 and XP-V cells, and it occurred at a frequency of 16-17%, significantly higher than previously reported. Interestingly, the misinsertion frequency of A opposite 8-oxoguanine was decreased in XP-V cells in the presence of aphidicolin, and misinsertion of G was observed. This modulation of the mutagenic specificity at 8-oxoguanine is consistent with the notion that while not essential for the bypass reaction, pol η and pol δ, when present, are involved in bypass of 8-oxoguanine in vivo

  15. Cryptotanshinone inhibits oxidized LDL-induced adhesion molecule expression via ROS dependent NF-κB pathways.

    Science.gov (United States)

    Zhao, Wenwen; Wu, Chuanhong; Chen, Xiuping

    2016-05-01

    Adhesion molecules, such as intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin, play important roles in the initial stage of atherosclerosis. Cryptotanshinone (CPT), a natural compound isolated from Salvia miltiorrhiza Bunge, exhibits anti-atherosclerotic activity although the underlying mechanisms remain elusive. In this study, the protective effect of CPT against oxidized low-density lipoprotein (ox-LDL)-induced adhesion molecule expression was investigated in human umbilical vein endothelial cells. Ox-LDL significantly induced ICAM-1, VCAM-1, and E-selectin expression at the mRNA and protein levels but reduced eNOS phosphorylation and NO generation, which were reversed by CPT pretreatment. Sodium nitroprusside, a NO donor, N-acetyl-L-cysteine (NAC), a reactive oxygen species (ROS) scavenger, and BAY117082, a NF-κB inhibitor, inhibited ox-LDL-induced ICAM-1, VCAM-1, and E-selectin expression. Ox-LDL-induced ROS production was significantly inhibited by CPT and NAC. Furthermore, ox-LDL activated the NF-κB signaling pathway by inducing phosphorylation of IKKβ and IκBα, promoting the interaction of IKKβ and IκBα, and increasing p65 nuclear translocation, which were significantly inhibited by CPT. In addition, CPT, NAC, and BAY117082 inhibited ox-LDL-induced membrane expression of ICAM-1, VCAM-1, E-selectin, and endothelial-monocyte adhesion and restored eNOS phosphorylation and NO generation. Results suggested that CPT inhibited ox-LDL-induced adhesion molecule expression by decreasing ROS and inhibiting the NF-κB pathways, which provides new insight into the anti-atherosclerotic mechanism of CPT. PMID:26647279

  16. Thickness Dependent Nanostructural, Morphological, Optical and Impedometric Analyses of Zinc Oxide-Gold Hybrids: Nanoparticle to Thin Film.

    Science.gov (United States)

    Perumal, Veeradasan; Hashim, Uda; Gopinath, Subash C B; Haarindraprasad, R; Liu, Wei-Wen; Poopalan, P; Balakrishnan, S R; Thivina, V; Ruslinda, A R

    2015-01-01

    The creation of an appropriate thin film is important for the development of novel sensing surfaces, which will ultimately enhance the properties and output of high-performance sensors. In this study, we have fabricated and characterized zinc oxide (ZnO) thin films on silicon substrates, which were hybridized with gold nanoparticles (AuNPs) to obtain ZnO-Aux (x = 10, 20, 30, 40 and 50 nm) hybrid structures with different thicknesses. Nanoscale imaging by field emission scanning electron microscopy revealed increasing film uniformity and coverage with the Au deposition thickness. Transmission electron microscopy analysis indicated that the AuNPs exhibit an increasing average diameter (5-10 nm). The face center cubic Au were found to co-exist with wurtzite ZnO nanostructure. Atomic force microscopy observations revealed that as the Au content increased, the overall crystallite size increased, which was supported by X-ray diffraction measurements. The structural characterizations indicated that the Au on the ZnO crystal lattice exists without any impurities in a preferred orientation (002). When the ZnO thickness increased from 10 to 40 nm, transmittance and an optical bandgap value decreased. Interestingly, with 50 nm thickness, the band gap value was increased, which might be due to the Burstein-Moss effect. Photoluminescence studies revealed that the overall structural defect (green emission) improved significantly as the Au deposition increased. The impedance measurements shows a decreasing value of impedance arc with increasing Au thicknesses (0 to 40 nm). In contrast, the 50 nm AuNP impedance arc shows an increased value compared to lower sputtering thicknesses, which indicated the presence of larger sized AuNPs that form a continuous film, and its ohmic characteristics changed to rectifying characteristics. This improved hybrid thin film (ZnO/Au) is suitable for a wide range of sensing applications. PMID:26694656

  17. Electrical dependence on the chemical composition of the gate dielectric in indium gallium zinc oxide thin-film transistors

    Science.gov (United States)

    Tari, Alireza; Lee, Czang-Ho; Wong, William S.

    2015-07-01

    Bottom-gate thin-film transistors were fabricated by depositing a 50 nm InGaZnO (IGZO) channel layer at 150 °C on three separate gate dielectric films: (1) thermal SiO2, (2) plasma-enhanced chemical-vapor deposition (PECVD) SiNx, and (3) a PECVD SiOx/SiNx dual-dielectric. X-ray photoelectron and photoluminescence spectroscopy showed the Vo concentration was dependent on the hydrogen concentration of the underlying dielectric film. IGZO films on SiNx (high Vo) and SiO2 (low Vo) had the highest and lowest conductivity, respectively. A PECVD SiOx/SiNx dual-dielectric layer was effective in suppressing hydrogen diffusion from the nitride layer into the IGZO and resulted in higher resistivity films.

  18. Density-dependent enhancement of methane oxidation activity and growth of Methylocystis sp. by a non-methanotrophic bacterium Sphingopyxis sp

    Directory of Open Access Journals (Sweden)

    So-Yeon Jeong

    2014-12-01

    Full Text Available Methanotrophs are a biological resource as they degrade the greenhouse gas methane and various organic contaminants. Several non-methanotrophic bacteria have shown potential to stimulate growth of methanotrophs when co-cultured, and however, the ecology is largely unknown. Effects of Sphingopyxis sp. NM1 on methanotrophic activity and growth of Methylocystis sp. M6 were investigated in this study. M6 and NM1 were mixed at mixing ratios of 9:1, 1:1, and 1:9 (v/v, using cell suspensions of 7.5 × 1011 cells L−1. Methane oxidation of M6 was monitored, and M6 population was estimated using fluorescence in situ hybridization (FISH. Real-time PCR was applied to quantify rRNA and expression of transcripts for three enzymes involved in the methane oxidation pathway. NM1 had a positive effect on M6 growth at a 1:9 ratio (p < 0.05, while no significant effects were observed at 9:1 and 1:1 ratios. NM1 enhanced the methane oxidation 1.34-fold at the 1:9 ratio. NM1 increased the population density and relative rRNA level of M6 by 2.4-fold and 5.4-fold at the 1:9 ratio, indicating that NM1 stimulated the population growth of M6. NM1 increased the relative transcriptional expression of all mRNA targets only at the 1:9 ratio. These results demonstrated that NM1 enhanced the methanotrophic activity and growth of M6, which was dependent on the proportion of NM1 present in the culture. This stimulation can be used as management and enhancement strategies for methanotrophic biotechnological processes.

  19. Interface states in Al2O3/AlGaN/GaN metal-oxide-semiconductor structure by frequency dependent conductance technique

    International Nuclear Information System (INIS)

    Frequency dependent conductance measurements are implemented to investigate the interface states in Al2O3/AlGaN/GaN metal-oxide-semiconductor (MOS) structures. Two types of device structures, namely, the recessed gate structure (RGS) and the normal gate structure (NGS), are studied in the experiment. Interface trap parameters including trap density Dit, trap time constant τit, and trap state energy ET in both devices have been determined. Furthermore, the obtained results demonstrate that the gate recess process can induce extra traps with shallower energy levels at the Al2O3/AlGaN interface due to the damage on the surface of the AlGaN barrier layer resulting from reactive ion etching (RIE). (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  20. Frequency dependent negative capacitance effect and dielectric properties of swift heavy ion irradiated Ni/oxide/n-GaAs Schottky diode

    Science.gov (United States)

    Bobby, A.; Shiwakoti, N.; Verma, S.; Asokan, K.; Antony, B. K.

    2016-05-01

    The Ni/n-GaAs Schottky barrier diode having thin interfacial oxide layer was subjected to 25 MeV C4+ ion irradiation at selected fluences. The in-situ capacitance and dielectric properties were investigated in the 1 KHz to 5 MHz frequency range. The results show a decrease in capacitance with increase in ion fluence at low frequencies. Interestingly, a negative capacitance effect was also observed in this frequency range in all the samples. As a consequence, changes were observed in parameters like series resistance, conductance, dielectric loss, dielectric constant, loss tangent and ac electrical conductivity. At high frequencies, the capacitance reaches the geometric value 'C0'. The results were interpreted in terms of the generation of irradiation induced traps, carrier capture and emission from deep and shallow states and its frequency dependent saturation effects.

  1. Gate voltage dependent 1/f noise variance model based on physical noise generation mechanisms in n-channel metal-oxide-semiconductor field-effect transistors

    Science.gov (United States)

    Arai, Yukiko; Aoki, Hitoshi; Abe, Fumitaka; Todoroki, Shunichiro; Khatami, Ramin; Kazumi, Masaki; Totsuka, Takuya; Wang, Taifeng; Kobayashi, Haruo

    2015-04-01

    1/f noise is one of the most important characteristics for designing analog/RF circuits including operational amplifiers and oscillators. We have analyzed and developed a novel 1/f noise model in the strong inversion, saturation, and sub-threshold regions based on SPICE2 type model used in any public metal-oxide-semiconductor field-effect transistor (MOSFET) models developed by the University of California, Berkeley. Our model contains two noise generation mechanisms that are mobility and interface trap number fluctuations. Noise variability dependent on gate voltage is also newly implemented in our model. The proposed model has been implemented in BSIM4 model of a SPICE3 compatible circuit simulator. Parameters of the proposed model are extracted with 1/f noise measurements for simulation verifications. The simulation results show excellent agreements between measurement and simulations.

  2. Temperature Dependent Electrical Transport in Al/Poly(4-vinyl phenol/p-GaAs Metal-Oxide-Semiconductor by Sol-Gel Spin Coating Method

    Directory of Open Access Journals (Sweden)

    Şadan Özden

    2016-01-01

    Full Text Available Deposition of poly(4-vinyl phenol insulator layer is carried out by applying the spin coating technique onto p-type GaAs substrate so as to create Al/poly(4-vinyl phenol/p-GaAs metal-oxide-semiconductor (MOS structure. Temperature was set to 80–320 K while the current-voltage (I-V characteristics of the structure were examined in the study. Ideality factor (n and barrier height (ϕb values found in the experiment ranged from 3.13 and 0.616 eV (320 K to 11.56 and 0.147 eV (80 K. Comparing the thermionic field emission theory and thermionic emission theory, the temperature dependent ideality factor behavior displayed that thermionic field emission theory is more valid than the latter. The calculated tunneling energy was 96 meV.

  3. Solvent-Dependent Reaction Pathways Operating in Copper(II) Tetrafluoroborate Promoted Oxidative Ring-Opening Reactions of Cyclopropyl Silyl Ethers.

    Science.gov (United States)

    Hasegawa, Eietsu; Nemoto, Kazuki; Nagumo, Ryosuke; Tayama, Eiji; Iwamoto, Hajime

    2016-04-01

    Oxidative ring-opening reactions of benzene-fused bicyclic cyclopropyl silyl ethers, promoted by copper(II) tetrafluoroborate, were investigated. The regioselectivity of cyclopropane ring-opening as well as product distributions were found to be highly dependent on the nature of the solvent. In alcohols, dimeric substances arising from external bond cleavage are major products. Radical rearrangement products are also formed in solvents such as ether and ethyl acetate. On the contrary, nucleophile addition to carbocation intermediates, generated by internal bond cleavage, occurs mainly in reactions taking place in acetonitrile. It is proposed that the observed solvent effects that govern the reaction pathways followed are a consequence of varying solvation of copper intermediates, which governs their reactivity and redox properties. In addition, the influence of counteranions of the copper salts, organonitriles, cyclic dienes, and substrate structures on the pathways followed in these reactions was also examined. PMID:26799089

  4. Spin-dependent transport properties of a GaMnAs-based vertical spin metal-oxide-semiconductor field-effect transistor structure

    International Nuclear Information System (INIS)

    We fabricate a vertical spin metal-oxide-semiconductor field-effect transistor (spin-MOSFET) structure, which is composed of an epitaxial single-crystal heterostructure with a ferromagnetic-semiconductor GaMnAs source/drain, and investigate its spin-dependent transport properties. We modulate the drain-source current IDS by ∼±0.5% with a gate-source voltage of ±10.8 V and also modulate IDS by up to 60% with changing the magnetization configuration of the GaMnAs source/drain at 3.5 K. The magnetoresistance ratio is more than two orders of magnitude higher than that obtained in the previous studies on spin MOSFETs. Our result shows that a vertical structure is one of the hopeful candidates for spin MOSFET when the device size is reduced to a sub-micron or nanometer scale

  5. Bioaugmentation of nitrate-dependent anaerobic ferrous oxidation by heterotrophic denitrifying sludge addition: A promising way for promotion of chemoautotrophic denitrification.

    Science.gov (United States)

    Wang, Ru; Zheng, Ping; Zhang, Meng; Zhao, He-Ping; Ji, Jun-Yuan; Zhou, Xiao-Xin; Li, Wei

    2015-12-01

    Nitrate-dependent anaerobic ferrous oxidation (NAFO) is a new and valuable bio-process for the treatment of wastewaters with low C/N ratio, and the NAFO process is in state of the art. The heterotrophic denitrifying sludge (HDS), possessing NAFO activity, was used as bioaugmentation to enhance NAFO efficiency. At a dosage of 6% (V/V), the removal of nitrate and ferrous was 2.4 times and 2.3 times of as primary, and the volumetric removal rate (VRR) of nitrate and ferrous was 2.4 times and 2.2 times of as primary. Tracing experiments of HDS indicated that the bioaugmentation on NAFO reactor was resulted from the NAFO activity by HDS itself. The predominant bacteria in HDS were identified as Thauera (52.5%) and Hyphomicrobium (20.0%) which were typical denitrifying bacteria and had potential ability to oxidize ferrous. In conclusion, HDS could serve as bioaugmentation or a new seeding sludge for operating high-efficiency NAFO reactors. PMID:26348287

  6. Thickness dependence of structural and optical properties of indium tin oxide nanofiber thin films prepared by electron beam evaporation onto quartz substrates

    Energy Technology Data Exchange (ETDEWEB)

    El-Nahass, M.M. [Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo 11757 (Egypt); El-Menyawy, E.M., E-mail: emad_elmenyawy@yahoo.com [Solid State Electronics Lab, Solid State Physics Department, National Research Center, Dokki, Cairo 12622 (Egypt)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Indium tin oxide thin films grow as nanofibers by e-beam evaporation. Black-Right-Pointing-Pointer The transparency of the films is strongly affected by film thickness. Black-Right-Pointing-Pointer Dielectric constant of the films is independent on film thickness. Black-Right-Pointing-Pointer Optical band gap and carrier concentration decrease with increasing film thickness. - Abstract: Indium tin oxide (ITO) thin films, produced by electron beam evaporation technique onto quartz substrates maintained at room temperature, are grown as nanofibers. The dependence of structural and optical properties of ITO thin films on the film thickness (99-662 nm) has been reported. The crystal structure and morphology of the films are investigated by X-ray diffraction and scanning electron microscope techniques, respectively. The particle size is found to increase with increasing film thickness without changing the preferred orientation along (2 2 2) direction. The optical properties of the films are investigated in terms of the measurements of the transmittance and reflectance determined at the normal incidence of the light in the wavelength range (250-2500 nm). The absorption coefficient and refractive index are calculated and the related optical parameters are evaluated. The optical band gap is found to decrease with the increase of the film thickness, whereas the refractive index is found to increase. The optical dielectric constant and the ratio of the free carrier concentration to its effective mass are estimated for the films.

  7. Thickness dependence of structural and optical properties of indium tin oxide nanofiber thin films prepared by electron beam evaporation onto quartz substrates

    International Nuclear Information System (INIS)

    Highlights: ► Indium tin oxide thin films grow as nanofibers by e-beam evaporation. ► The transparency of the films is strongly affected by film thickness. ► Dielectric constant of the films is independent on film thickness. ► Optical band gap and carrier concentration decrease with increasing film thickness. - Abstract: Indium tin oxide (ITO) thin films, produced by electron beam evaporation technique onto quartz substrates maintained at room temperature, are grown as nanofibers. The dependence of structural and optical properties of ITO thin films on the film thickness (99–662 nm) has been reported. The crystal structure and morphology of the films are investigated by X-ray diffraction and scanning electron microscope techniques, respectively. The particle size is found to increase with increasing film thickness without changing the preferred orientation along (2 2 2) direction. The optical properties of the films are investigated in terms of the measurements of the transmittance and reflectance determined at the normal incidence of the light in the wavelength range (250–2500 nm). The absorption coefficient and refractive index are calculated and the related optical parameters are evaluated. The optical band gap is found to decrease with the increase of the film thickness, whereas the refractive index is found to increase. The optical dielectric constant and the ratio of the free carrier concentration to its effective mass are estimated for the films.

  8. The putative endoglucanase PcGH61D from Phanerochaete chrysosporium is a metal-dependent oxidative enzyme that cleaves cellulose.

    Directory of Open Access Journals (Sweden)

    Bjørge Westereng

    Full Text Available Many fungi growing on plant biomass produce proteins currently classified as glycoside hydrolase family 61 (GH61, some of which are known to act synergistically with cellulases. In this study we show that PcGH61D, the gene product of an open reading frame in the genome of Phanerochaete chrysosporium, is an enzyme that cleaves cellulose using a metal-dependent oxidative mechanism that leads to generation of aldonic acids. The activity of this enzyme and its beneficial effect on the efficiency of classical cellulases are stimulated by the presence of electron donors. Experiments with reduced cellulose confirmed the oxidative nature of the reaction catalyzed by PcGH61D and indicated that the enzyme may be capable of penetrating into the substrate. Considering the abundance of GH61-encoding genes in fungi and genes encoding their functional bacterial homologues currently classified as carbohydrate binding modules family 33 (CBM33, this enzyme activity is likely to turn out as a major determinant of microbial biomass-degrading efficiency.

  9. Electrical dependence on the chemical composition of the gate dielectric in indium gallium zinc oxide thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Tari, Alireza, E-mail: atari@uwaterloo.ca; Lee, Czang-Ho; Wong, William S. [Department of Electrical and Computer Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada)

    2015-07-13

    Bottom-gate thin-film transistors were fabricated by depositing a 50 nm InGaZnO (IGZO) channel layer at 150 °C on three separate gate dielectric films: (1) thermal SiO{sub 2}, (2) plasma-enhanced chemical-vapor deposition (PECVD) SiN{sub x}, and (3) a PECVD SiO{sub x}/SiN{sub x} dual-dielectric. X-ray photoelectron and photoluminescence spectroscopy showed the V{sub o} concentration was dependent on the hydrogen concentration of the underlying dielectric film. IGZO films on SiN{sub x} (high V{sub o}) and SiO{sub 2} (low V{sub o}) had the highest and lowest conductivity, respectively. A PECVD SiO{sub x}/SiN{sub x} dual-dielectric layer was effective in suppressing hydrogen diffusion from the nitride layer into the IGZO and resulted in higher resistivity films.

  10. Size-Dependent Toxicity Differences of Intratracheally Instilled Manganese Oxide Nanoparticles: Conclusions of a Subacute Animal Experiment.

    Science.gov (United States)

    Máté, Zsuzsanna; Horváth, Edina; Kozma, Gábor; Simon, Tímea; Kónya, Zoltán; Paulik, Edit; Papp, András; Szabó, Andrea

    2016-05-01

    Incomplete information on toxicological differences of micro- and nanometer-sized particles raised concerns about the effects of the latter on health and environment. Besides chemical composition, size and surface-to-volume ratio of nanoparticles (NPs) can affect toxicity. To investigate size-dependent toxicity differences, we used particles made of dioxide of the neurotoxic heavy metal manganese (Mn), typically found in inhaled metal fumes, in three size ranges (size A, 9.14 ± 1.98 nm; size B, 42.36 ± 8.06 nm; size C, 118.31 ± 25.37 nm). For modeling the most frequent route of exposure to Mn, NPs were given to rats for 6 weeks by intratracheal instillation. Of each NP size, 3 or 6 mg/kg body weight was given while control animals were vehicle treated. Neurotoxicity was assessed by measuring spontaneous locomotor activity in an open field and by recording spontaneous and evoked electrical activity from the somatosensory cortical area. Mn content of brain, lung, and blood, measured by ICP-MS, were correlated to the observed functional alterations to see the relationship between Mn load and toxic effects. Body weight gain and organ weights were measured as general toxicological indices. The toxicity of size A and size B NPs proved to be stronger compared to size C NPs, seen most clearly in decreased body weight gain and altered spontaneous cortical activity, which were also well correlated to the internal Mn dose. Our results showed strong effect of size on NP toxicity, thus, beyond inappropriateness of toxicity data of micrometer-sized particles in evaluation of NP exposure, differentiation within the nano range may be necessary. PMID:26384687

  11. Huperzine A Alleviates Oxidative Glutamate Toxicity in Hippocampal HT22 Cells via Activating BDNF/TrkB-Dependent PI3K/Akt/mTOR Signaling Pathway.

    Science.gov (United States)

    Mao, Xiao-Yuan; Zhou, Hong-Hao; Li, Xi; Liu, Zhao-Qian

    2016-08-01

    Oxidative glutamate toxicity is involved in diverse neurological disorders including epilepsy and ischemic stroke. Our present work aimed to assess protective effects of huperzine A (HupA) against oxidative glutamate toxicity in a mouse-derived hippocampal HT22 cells and explore its potential mechanisms. Cell survival and cell injury were analyzed by MTT method and LDH release assay, respectively. The production of ROS was measured by detection kits. Protein expressions of BDNF, phosphor-TrkB (p-TrkB), TrkB, phosphor-Akt (p-Akt), Akt, phosphor-mTOR (p-mTOR), mTOR, phosphor-p70s6 (p-p70s6) kinase, p70s6 kinase, Bcl-2, Bax, and β-actin were assayed via Western blot analysis. Enzyme-linked immunosorbent assay was employed to measure the contents of nerve growth factor, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4). Our findings illustrated 10 μM HupA for 24 h significantly protected HT22 from cellular damage and suppressed the generation of ROS. Additionally, after treating with LY294002 or wortmannin [the selective inhibitors of phosphatidylinositol 3 kinase (PI3K)], HupA dramatically prevented the down-regulations of p-Akt, p-mTOR, and p-p70s6 kinase in HT22 cells under oxidative toxicity. Furthermore, it was observed that the protein levels of BDNF and p-TrkB were evidently enhanced after co-treatment with HupA and glutamate in HT22 cells. The elevations of p-Akt and p-mTOR were abrogated under toxic conditions after blockade of TrkB by TrkB IgG. Cellular apoptosis was significantly suppressed (decreased caspase-3 activity and enhanced Bcl-2 protein level) after HupA treatment. It was concluded that HupA attenuated oxidative glutamate toxicity in murine hippocampal HT22 cells via activating BDNF/TrkB-dependent PI3K/Akt/mTOR signaling pathway. PMID:26440805

  12. Aberrant accumulation of phospholipase C-delta in Alzheimer brains.

    OpenAIRE

    Shimohama, S.; Homma, Y.; Suenaga, T.; Fujimoto, S; Taniguchi, T; Araki, W.; Yamaoka, Y; Takenawa, T.; Kimura, J

    1991-01-01

    Since phosphoinositide-specific phospholipase C (PLC) is one of the key molecules in signal transduction, the authors assessed its involvement in Alzheimer's disease (AD). Immunostaining of a specific antibody against the PLC isozyme, PLC-delta, demonstrated that this enzyme was abnormally accumulated in neurofibrillary tangles (NFT), the neurites surrounding senile plaque (SP) cores, and neuropil threads in AD brains. Western blot analysis confirmed that PLC-delta was concentrated in the pai...

  13. Nitric oxide signalling modulates synaptic inhibition in the superior paraolivary nucleus (SPN via cGMP-dependent suppression of KCC2

    Directory of Open Access Journals (Sweden)

    Hila Asraf

    2014-06-01

    Full Text Available Glycinergic inhibition plays a central role in the auditory brainstem circuitries involved in sound localization and in the encoding of temporal action potential firing patterns. Modulation of this inhibition has the potential to fine-tune information processing in these networks. Here we show that nitric oxide (NO signalling in the auditory brainstem (where activity-dependent generation of NO is documented modulates the strength of inhibition by changing the chloride equilibrium potential. Recent evidence demonstrates that large inhibitory postsynaptic currents (IPSCs in neurons of the superior paraolivary nucleus (SPN are enhanced by a very low intracellular chloride concentration, generated by the neuronal potassium chloride co-transporter (KCC2 expressed in the postsynaptic neurons. Our data show that modulation by NO caused a 15mV depolarizing shift of the IPSC reversal potential, reducing the strength of inhibition in SPN neurons, without changing the threshold for action potential firing. Regulating inhibitory strength, through cGMP-dependent changes in the efficacy of KCC2 in the target neuron provides a postsynaptic mechanism for rapidly controlling the inhibitory drive, without altering the timing or pattern of the afferent spike train. Therefore, this NO-mediated suppression of KCC2 can modulate inhibition in one target nucleus (SPN, without influencing inhibitory strength of other target nuclei (MSO, LSO even though they are each receiving collaterals from the same afferent nucleus (a projection from the medial nucleus of the trapezoid body, MNTB.

  14. Diversity of electronic transitions and photoluminescence properties of p-type cuprous oxide films: A temperature-dependent spectral transmittance study

    International Nuclear Information System (INIS)

    Cuprous oxide films have been deposited on quartz substrates by a sol-gel method under various annealing temperatures. The X-ray diffraction analysis and Raman scattering show that all the films are of pure Cu2O phase. From comparison of photoluminescence with 488 and 325 nm laser excitations, the electronic transition energies and intensities present the annealing-temperature dependent behavior. The electronic band structures of the Cu2O film annealed at 800 °C, especially for the contribution of exciton series and high energy transitions, have been investigated by temperature dependent transmittance. The extracted refraction index and the high frequency dielectric constant both abruptly decrease until the temperature rises up to 100 K. Six transitions can be clearly identified and the red shift trend of Eo3-Eo5 transition energies with increasing the temperature can be found. Moreover, the anomalous behavior takes place at about 200 K from the Eo6 transition. The singularities indicate that the change in the crystalline and electronic band structure occurs as the temperature near 100 K and 200 K for the film

  15. Time-Dependent and Organ-Specific Changes in Mitochondrial Function, Mitochondrial DNA Integrity, Oxidative Stress and Mononuclear Cell Infiltration in a Mouse Model of Burn Injury.

    Directory of Open Access Journals (Sweden)

    Bartosz Szczesny

    Full Text Available Severe thermal injury induces a pathophysiological response that affects most of the organs within the body; liver, heart, lung, skeletal muscle among others, with inflammation and hyper-metabolism as a hallmark of the post-burn damage. Oxidative stress has been implicated as a key component in development of inflammatory and metabolic responses induced by burn. The goal of the current study was to evaluate several critical mitochondrial functions in a mouse model of severe burn injury. Mitochondrial bioenergetics, measured by Extracellular Flux Analyzer, showed a time dependent, post-burn decrease in basal respiration and ATP-turnover but enhanced maximal respiratory capacity in mitochondria isolated from the liver and lung of animals subjected to burn injury. Moreover, we detected a tissue-specific degree of DNA damage, particularly of the mitochondrial DNA, with the most profound effect detected in lungs and hearts of mice subjected to burn injury. Increased mitochondrial biogenesis in lung tissue in response to burn injury was also observed. Burn injury also induced time dependent increases in oxidative stress (measured by amount of malondialdehyde and neutrophil infiltration (measured by myeloperoxidase activity, particularly in lung and heart. Tissue mononuclear cell infiltration was also confirmed by immunohistochemistry. The amount of poly(ADP-ribose polymers decreased in the liver, but increased in the heart in later time points after burn. All of these biochemical changes were also associated with histological alterations in all three organs studied. Finally, we detected a significant increase in mitochondrial DNA fragments circulating in the blood immediately post-burn. There was no evidence of systemic bacteremia, or the presence of bacterial DNA fragments at any time after burn injury. The majority of the measured parameters demonstrated a sustained elevation even at 20-40 days post injury suggesting a long-lasting effect of thermal

  16. Changes in cytochrome-oxidase oxidation in the occipital cortex during visual simulation: improvement in sensitivity by the determination of the wavelength dependence of the differential pathlength

    Science.gov (United States)

    Kohl-Bareis, Matthias; Nolte, Christian; Heekeren, Hauke R.; Horst, Susanne; Scholz, J.; Obrig, Hellmuth; Villringer, Arno

    1998-01-01

    In this study we assess changes in the hemoglobin oxygenation (oxy-Hb, deoxy-Hb) and the Cytochrome-C-Oxidase redox state (Cyt-ox) in the occipital cortex during visual stimulation by near infrared spectroscopy. For the calculation of changes in oxy-Hb, deoxy-Hb and Cyt-ox from attenuation data via a modified Beer-Lambert equation, the wavelength dependence of the differential pathlength factor (DPF), i.e. the ratio of the mean optical pathlength and the physical light-source-detector separation, has to be taken into account. The wavelength dependence of the DPF determines the crosstalk between the different concentrations and is therefore essential for a high sensitivity. Here a simple method is suggested to estimate the wavelength dependence of the DPF((lambda) ) from pulse induced attenuation changes measured on the head of adult humans. The essence is that the DPF is the ratio of the attenuation changes over absorption coefficient changes and the spectral form of the pulse correlated absorption coefficient change is proportional to the extinction coefficient of blood. Indicators for the validity of the DPF((lambda) ) derived for wavelengths between 700 and 970 nm are the stability of the calculated oxy-Hb, deoxy-Hb and Cyt-ox signals with variations of the wavelength range included for their calculation and its overall agreement with the data available from the literature. The DPF derived from pulse measurements was used for the analysis of attenuation data from cortical stimulations. We show that Cyt-ox in the occipital cortex of human subjects is transiently oxidized during visual stimulation.

  17. Calcium-dependent nitric oxide production is involved in the cytoprotective properties of n-acetylcysteine in glycochenodeoxycholic acid-induced cell death in hepatocytes

    International Nuclear Information System (INIS)

    The intracellular oxidative stress has been involved in bile acid-induced cell death in hepatocytes. Nitric oxide (NO) exerts cytoprotective properties in glycochenodeoxycholic acid (GCDCA)-treated hepatocytes. The study evaluated the involvement of Ca2+ on the regulation of NO synthase (NOS)-3 expression during N-acetylcysteine (NAC) cytoprotection against GCDCA-induced cell death in hepatocytes. The regulation of Ca2+ pools (EGTA or BAPTA-AM) and NO (L-NAME or NO donor) production was assessed during NAC cytoprotection in GCDCA-treated HepG2 cells. The stimulation of Ca2+ entrance was induced by A23187 in HepG2. Cell death, Ca2+ mobilization, NOS-1, -2 and -3 expression, AP-1 activation, and NO production were evaluated. GCDCA reduced intracellular Ca2+ concentration and NOS-3 expression, and enhanced cell death in HepG2. NO donor prevented, and L-NAME enhanced, GCDCA-induced cell death. The reduction of Ca2+ entry by EGTA, but not its release from intracellular stores by BAPTA-AM, enhanced cell death in GCDCA-treated cells. The stimulation of Ca2+ entrance by A23187 reduced cell death and enhanced NOS-3 expression in GCDCA-treated HepG2 cells. The cytoprotective properties of NAC were related to the recovery of intracellular Ca2+ concentration, NOS-3 expression and NO production induced by GCDCA-treated HepG2 cells. The increase of NO production by Ca2+-dependent NOS-3 expression during NAC administration reduces cell death in GCDCA-treated hepatocytes.

  18. Using amorphous manganese oxide for remediation of smelter-polluted soils: a pH-dependent long-term stability study

    Science.gov (United States)

    Ettler, Vojtech; Tomasova, Zdenka; Komarek, Michael; Mihaljevic, Martin; Sebek, Ondrej

    2015-04-01

    In soil systems, manganese (Mn) oxides are commonly found to be powerful sorbents of metals and metalloids and are thus potentially useful in soil remediation. A novel amorphous manganese oxide (AMO) and a Pb smelter-polluted agricultural soil amended with the AMO and incubated for 2 and 6 months were subjected to a pH-static leaching procedure (pH = 3 - 8) to verify the chemical stabilization effect on metals and metalloids. The AMO stability in pure water was pH-dependent with the highest Mn release at pH 3 (47% dissolved) and the lowest at pH 8 (0.14% dissolved). Secondary rhodochrosite (MnCO3) was formed at the AMO surfaces at pH > 5. The AMO dissolved significantly less after 6 months of incubation. Sequential extraction analysis indicated that "labile" fraction of As, Pb and Sb in soil significantly decreased after AMO amendment. The pH-static experiments indicated that no effect on leaching was observed for Cd and Zn after AMO treatments, whereas the leaching of As, Cu, Pb and Sb decreased down to 20%, 35%, 7% and 11% of the control, respectively. The remediation efficiency was more pronounced under acidic conditions and the time of incubation generally led to increased retention of the targeted contaminants. The AMO was found to be a promising agent for the chemical stabilization of polluted soils and other in situ applications need to be evaluated. This study was supported by the Czech Science Foundation (GAČR 15-07117S).

  19. Cobalt chloride decreases fibroblast growth factor-21 expression dependent on oxidative stress but not hypoxia-inducible factor in Caco-2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yanlong [School of Pharmacy, Wenzhou Medical College, Wenzhou (China); Department of Medicine, University of Louisville, Louisville, KY (United States); Wang, Chunhong [Second Hospital, Jilin University, Changchun (China); Department of Medicine, University of Louisville, Louisville, KY (United States); Wang, Yuhua [College of Food Science and Engineering, Jilin Agricultural University, Changchun (China); Department of Medicine, University of Louisville, Louisville, KY (United States); Ma, Zhenhua [First Hospital, Xi' an Jiaotong University, Xi' an (China); Department of Medicine, University of Louisville, Louisville, KY (United States); Xiao, Jian [School of Pharmacy, Wenzhou Medical College, Wenzhou (China); McClain, Craig [Department of Medicine, University of Louisville, Louisville, KY (United States); Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY (United States); Alcohol Research Center, University of Louisville, Louisville, KY (United States); Robley Rex Veterans Affairs Medical Center, Louisville, KY (United States); Li, Xiaokun [School of Pharmacy, Wenzhou Medical College, Wenzhou (China); Feng, Wenke, E-mail: wenke.feng@louisville.edu [School of Pharmacy, Wenzhou Medical College, Wenzhou (China); Department of Medicine, University of Louisville, Louisville, KY (United States); Alcohol Research Center, University of Louisville, Louisville, KY (United States)

    2012-10-15

    Fibroblast growth factor-21 (FGF21) is a potential metabolic regulator with multiple beneficial effects on metabolic diseases. FGF21 is mainly expressed in the liver, but is also found in other tissues including the intestine, which expresses β-klotho abundantly. The intestine is a unique organ that operates in a physiologically hypoxic environment, and is responsible for the fat absorption processes including triglyceride breakdown, re-synthesis and absorption into the portal circulation. In the present study, we investigated the effects of hypoxia and the chemical hypoxia inducer, cobalt chloride (CoCl{sub 2}), on FGF21 expression in Caco-2 cells and the consequence of fat accumulation. Physical hypoxia (1% oxygen) and CoCl{sub 2} treatment decreased both FGF21 mRNA and secreted protein levels. Gene silence and inhibition of hypoxia-inducible factor-α (HIFα) did not affect the reduction of FGF21 mRNA and protein levels by hypoxia. However, CoCl{sub 2} administration caused a significant increase in oxidative stress. The addition of n-acetylcysteine (NAC) suppressed CoCl{sub 2}-induced reactive oxygen species (ROS) formation and completely negated CoCl{sub 2}-induced FGF21 loss. mRNA stability analysis demonstrated that the CoCl{sub 2} administration caused a remarkable reduction in FGF21 mRNA stability. Furthermore, CoCl{sub 2} increased intracellular triglyceride (TG) accumulation, along with a reduction in mRNA levels of lipid lipase, hormone sensitive lipase (HSL) and adipose triglyceride lipase (ATGL), and an increase of sterol regulatory element-binding protein-1c (SREBP1c) and stearoyl-coenzyme A (SCD1). Addition of both NAC and recombinant FGF21 significantly attenuated the CoCl{sub 2}-induced TG accumulation. In conclusion, the decrease of FGF21 in Caco-2 cells by chemical hypoxia is independent of HIFα, but dependent on an oxidative stress-mediated mechanism. The regulation of FGF21 by hypoxia may contribute to intestinal lipid metabolism and

  20. Cobalt chloride decreases fibroblast growth factor-21 expression dependent on oxidative stress but not hypoxia-inducible factor in Caco-2 cells

    International Nuclear Information System (INIS)

    Fibroblast growth factor-21 (FGF21) is a potential metabolic regulator with multiple beneficial effects on metabolic diseases. FGF21 is mainly expressed in the liver, but is also found in other tissues including the intestine, which expresses β-klotho abundantly. The intestine is a unique organ that operates in a physiologically hypoxic environment, and is responsible for the fat absorption processes including triglyceride breakdown, re-synthesis and absorption into the portal circulation. In the present study, we investigated the effects of hypoxia and the chemical hypoxia inducer, cobalt chloride (CoCl2), on FGF21 expression in Caco-2 cells and the consequence of fat accumulation. Physical hypoxia (1% oxygen) and CoCl2 treatment decreased both FGF21 mRNA and secreted protein levels. Gene silence and inhibition of hypoxia-inducible factor-α (HIFα) did not affect the reduction of FGF21 mRNA and protein levels by hypoxia. However, CoCl2 administration caused a significant increase in oxidative stress. The addition of n-acetylcysteine (NAC) suppressed CoCl2-induced reactive oxygen species (ROS) formation and completely negated CoCl2-induced FGF21 loss. mRNA stability analysis demonstrated that the CoCl2 administration caused a remarkable reduction in FGF21 mRNA stability. Furthermore, CoCl2 increased intracellular triglyceride (TG) accumulation, along with a reduction in mRNA levels of lipid lipase, hormone sensitive lipase (HSL) and adipose triglyceride lipase (ATGL), and an increase of sterol regulatory element-binding protein-1c (SREBP1c) and stearoyl-coenzyme A (SCD1). Addition of both NAC and recombinant FGF21 significantly attenuated the CoCl2-induced TG accumulation. In conclusion, the decrease of FGF21 in Caco-2 cells by chemical hypoxia is independent of HIFα, but dependent on an oxidative stress-mediated mechanism. The regulation of FGF21 by hypoxia may contribute to intestinal lipid metabolism and absorption. -- Graphical abstract: Physical and

  1. Minimum Alveolar Concentration Needed to Block Adrenergic Response of Sevoflurane with Nitrous Oxide Varies Depending on the Stimulation Sites in Adult Surgical Patients

    Directory of Open Access Journals (Sweden)

    Tetsu Kimura

    2015-02-01

    Full Text Available Background We examined whether minimum alveolar anesthetic concentration needed to block adrenergic response (MAC-BAR of sevoflurane with nitrous oxide (N2O varies depending on body surface sites to which noxious stimuli are applied. Methods Seventy-seven ASA I adult patients, aged 18-50 years old, were anesthetized with sevoflurane and 66% N2O in O2, and their tracheas were intubated. The anesthesia was maintained with 66% N2O in O2 plus sevoflurane at predetermined end-tidal concentrations (0.8, 1.1, 1.4, 1.7, 2.0, 2.3, or 2.6%, n = 11 in each concentration for at least 15 minutes. Heart rate (HR and non-invasive blood pressure (BP was recorded at 1-minute interval automatically. As a noxious stimulus, electrical tetanic stimulation with a 15 sec burst of 50 Hz, 0.25 msec square-wave, 55 mA electric current was applied at three different sites; forehead, abdomen, or thigh. A positive cardiovascular response was defined as an increase of either mean BP or HR by more than 15% from the pre-stimulation value. Logistic regression analysis was used to determine MAC-BAR. Results MAC-BAR of sevoflurane with 66% N2O obtained by stimulating forehead, abdomen, and thigh were 2.01% (95% CI: 1.70-2.57%, 1.71% (1.13-2.74%, and 1.31% (0.77-1.66%, respectively. MAC-BAR on the forehead was significantly higher than that on the thigh. Conclusion MAC-BAR of sevoflurane with 66% N2O varied depending on the body surface sites to which noxious stimuli were applied. These findings support our clinical impression that sensitivities to pain vary among body surface sites, and that anesthetic requirement to stabilize hemodynamic variables vary among surgical sites.

  2. Characterization of pH dependent Mn(II) oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

    OpenAIRE

    Tsing eBohu; Santelli, Cara M.; Denise eAkob; Neu, Thomas R.; Valerian eCiobota; Petra eRösch; Juergen ePopp; Sandor eNietzsche; Kirsten eKüsel

    2015-01-01

    Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II) at both acidic and neutral pH using differen...

  3. 17β-estradiol potentiates endothelium-dependent nitric oxide- and hyperpolarization-mediated relaxations in blood vessels of male but not female apolipoprotein-E deficient mice.

    Science.gov (United States)

    Kong, Billy W C; Vanhoutte, Paul M; Man, Ricky Y K; Leung, Susan W S

    2015-08-01

    The present study investigated the influence of gender on the changes underlying endothelial dysfunction in hyperlipidemia during aging. Isometric tension in rings (with endothelium) of the aortae and superior mesenteric arteries from apolipoprotein-E deficient mice was determined in wire myographs. Nitric oxide (NO)- and endothelium-dependent hyperpolarization (EDH)-mediated relaxations were smaller in the aortae and mesenteric arteries of 32weeks old males than eight weeks old males. In females, NO- and EDH-mediated relaxations were impaired only at 84weeks of age. The levels of reactive oxygen species were elevated in the blood vessels of 32weeks old males, but not females. Acute in vitro treatment with 17β-estradiol and apocynin improved NO- and EDH-mediated relaxations in 32weeks old males but not in 84weeks old males. Relaxations to SKA-31, activator of intermediate (IKCa) and small (SKCa) conductance calcium-activated potassium channels, were attenuated in the mesenteric arteries of 32weeks old males. Such impairment was restored by acute treatment with apocynin. These findings suggest that male hyperlipidemic mice develop endothelial dysfunction at an earlier age than females. This endothelial dysfunction is associated with impaired NO bioavailability and reduced IKCa and SKCa activity. Apocynin and 17β-estradiol restore the endothelial function only in younger male animals but not in older male or female animals. PMID:25869512

  4. Dependence of polarity inversion on V/III ratio in ‑c-GaN growth by oxide vapor phase epitaxy

    Science.gov (United States)

    Taniyama, Yuki; Yamaguchi, Yohei; Takatsu, Hiroaki; Sumi, Tomoaki; Kitamoto, Akira; Imade, Mamoru; Yoshimura, Masashi; Isemura, Masashi; Mori, Yusuke

    2016-05-01

    One of the issues in bulk c-GaN growth is the decrease in the diameter of crystals with an increase in thickness owing to the appearance of inclined \\{ 10\\bar{1}1\\} and \\{ 10\\bar{1}2\\} facets. In this study, we performed ‑c-GaN growth by oxide vapor phase epitaxy (OVPE). As a result, truncated-inverted-pyramidal crystals were successfully grown on dot-patterned ‑c-GaN substrates. The diameter of the top surface of crystals was larger than that of windows. We further investigated the dependence of the ratio of inversion-domain area to growth area (R ID) on growth temperature, V/III ratio, and growth rate. The remained results revealed that R ID decreased with increasing growth temperature and V/III ratio, and kept constant for growth rate. Additionally, an epitaxial layer on ‑c-GaN substrates with a growth rate of 12.4 µm/h and an R ID as low as 3.8% was obtained under an NH3 partial pressure (P NH3) of 83 kPa at 1200 °C.

  5. Molecular Fingerprint and Dominant Environmental Factors of Nitrite-Dependent Anaerobic Methane-Oxidizing Bacteria in Sediments from the Yellow River Estuary, China

    Science.gov (United States)

    Yan, Pengze; Li, Mingcong; Wei, Guangshan; Li, Han; Gao, Zheng

    2015-01-01

    Nitrite-dependent anaerobic methane oxidation (n-damo) is performed by “Candidatus Methylomirabilis oxyfera” (M. oxyfera), which connects the carbon and nitrogen global nutrient cycles. In the present study, M. oxyfera-like bacteria sequences were successfully recovered from Yellow River Estuary sediments using specific primers for 16S rRNA and pmoA genes. A M. oxyfera-like sequences analysis based on the 16S rRNA gene revealed greater diversity compared with the pmoA gene; the 16S rRNA gene sequences retrieved from the Yellow River Estuary sediments belong to groups A as well as B and were mainly found in freshwater habitats. Quantitative PCR showed that 16S rRNA gene abundance varied from 9.28±0.11×103 to 2.10±0.13×105 copies g-1 (dry weight), and the pmoA gene abundance ranged from 8.63±0.50×103 to 1.83±0.18×105 copies g-1 (dry weight). A correlation analysis showed that the total organic carbon (TOC) and ammonium (NH4+) as well as the ratio of total phosphorus to total nitrogen (TP/TN) influenced the M. oxyfera-like bacteria distribution in the Yellow River Estuary sediments. These findings will aid in understanding the n-damo bacterial distribution pattern as well as their correlation with surrounding environmental factors in temperate estuarine ecosystems. PMID:26368535

  6. Composition-dependent electrocatalytic activity of palladium-iridium binary alloy nanoparticles supported on the multiwalled carbon nanotubes for the electro-oxidation of formic acid.

    Science.gov (United States)

    Bao, Jianming; Dou, Meiling; Liu, Haijing; Wang, Feng; Liu, Jingjun; Li, Zhilin; Ji, Jing

    2015-07-22

    Surface-functionalized multiwalled carbon nanotubes (MWCNTs) supported Pd100-xIrx binary alloy nanoparticles (Pd100-xIrx/MWCNT) with tunable Pd/Ir atomic ratios were synthesized by a thermolytic process at varied ratios of bis(acetylacetonate) palladium(II) and iridium(III) 2,4-pentanedionate precursors and then applied as the electrocatalyst for the formic acid electro-oxidation. The X-ray diffraction pattern (XRD) and transmission electron microscope (TEM) analysis showed that the Pd100-xIrx alloy nanoparticles with the average size of 6.2 nm were uniformly dispersed on the MWCNTs and exhibited a single solid solution phase with a face-centered cubic structure. The electrocatalytic properties were evaluated through the cyclic voltammetry and chronoamperometry tests, and the results indicated that both the activity and stability of Pd100-xIrx/MWCNT were strongly dependent on the Pd/Ir atomic ratios: the best electrocatalytic performance in terms of onset potential, current density, and stability against CO poisoning was obtained for the Pd79Ir21/MWCNT. Moreover, compared with pure Pd nanoparticles supported on MWCNTs (Pd/MWCNT), the Pd79Ir21/MWCNT exhibited enhanced steady-state current density and higher stability, as well as maintained excellent electrocatalytic activity in high concentrated formic acid solution, which was attributed to the bifunctional effect through alloying Pd with transition metal. PMID:26132867

  7. Universal dependence of hydrogen oxidation and evolution reaction activity of platinum-group metals on pH and hydrogen binding energy

    Science.gov (United States)

    Zheng, Jie; Sheng, Wenchao; Zhuang, Zhongbin; Xu, Bingjun; Yan, Yushan

    2016-01-01

    Understanding how pH affects the activity of hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) is key to developing active, stable, and affordable HOR/HER catalysts for hydroxide exchange membrane fuel cells and electrolyzers. A common linear correlation between hydrogen binding energy (HBE) and pH is observed for four supported platinum-group metal catalysts (Pt/C, Ir/C, Pd/C, and Rh/C) over a broad pH range (0 to 13), suggesting that the pH dependence of HBE is metal-independent. A universal correlation between exchange current density and HBE is also observed on the four metals, indicating that they may share the same elementary steps and rate-determining steps and that the HBE is the dominant descriptor for HOR/HER activities. The onset potential of CO stripping on the four metals decreases with pH, indicating a stronger OH adsorption, which provides evidence against the promoting effect of adsorbed OH on HOR/HER. PMID:27034988

  8. Hollow superparamagnetic iron oxide nanoshells as a hydrophobic anticancer drug carrier: intracelluar pH-dependent drug release and enhanced cytotoxicity

    Science.gov (United States)

    Zhu, Xiao-Ming; Yuan, Jing; Leung, Ken Cham-Fai; Lee, Siu-Fung; Sham, Kathy W. Y.; Cheng, Christopher H. K.; Au, Doris W. T.; Teng, Gao-Jun; Ahuja, Anil T.; Wang, Yi-Xiang J.

    2012-08-01

    With curcumin and doxorubicin (DOX) base as model drugs, intracellular delivery of hydrophobic anticancer drugs by hollow structured superparamagnetic iron oxide (SPIO) nanoshells (hydrodynamic diameter: 191.9 +/- 2.6 nm) was studied in glioblastoma U-87 MG cells. SPIO nanoshell-based encapsulation provided a stable aqueous dispersion of the curcumin. After the SPIO nanoshells were internalized by U-87 MG cells, they localized at the acidic compartments of endosomes and lysosomes. In endosome/lysosome-mimicking buffers with a pH of 4.5-5.5, pH-dependent drug release was observed from curcumin or DOX loaded SPIO nanoshells (curcumin/SPIO or DOX/SPIO). Compared with the free drug, the intracellular curcumin content delivered via curcumin/SPIO was 30 fold higher. Increased intracellular drug content for DOX base delivered via DOX/SPIO was also confirmed, along with a fast intracellular DOX release that was attributed to its protonation in the acidic environment. DOX/SPIO enhanced caspase-3 activity by twofold compared with free DOX base. The concentration that induced 50% cytotoxic effect (CC50) was 0.05 +/- 0.03 μg ml-1 for DOX/SPIO, while it was 0.13 +/- 0.02 μg ml-1 for free DOX base. These results suggested SPIO nanoshells might be a promising intracellular carrier for hydrophobic anticancer drugs.

  9. Fucoidan protects ARPE-19 cells from oxidative stress via normalization of reactive oxygen species generation through the Ca²⁺-dependent ERK signaling pathway.

    Science.gov (United States)

    Li, Xiaoxia; Zhao, Haiyan; Wang, Qingfa; Liang, Hongyan; Jiang, Xiaofeng

    2015-05-01

    Diabetic retinopathy (DR) is a common complication of diabetes mellitus (DM) and it is the main cause of loss of vision. In previous years, interest in the biological activities of marine organisms has intensified. The effect of fucoidan from the seaweed Fucus vesiculosus on the molecular mechanisms of numerous diseases has been studied, while to date, its effect on DR was yet to be investigated. Therefore, the aim of the present study was to evaluate the role of fucoidan in DR. The human retinal pigment epithelial cell line ARPE‑19 was exposed to high D‑glucose in the presence or absence of fucoidan. Cell viability was monitored using MTT and lactate dehydrogenase assays. The intracellular reactive oxygen species (ROS) generation was measured using fluorescence spectrophotometry. Cell apoptosis was measured by flow cytometry using Annexin V‑fluorescein isothiocyanate staining. Ca2+ influx was measured with a calcium imaging system and the activation of the extracellular signal‑regulated kinase (ERK) protein was evaluated using western blot analysis. The non‑toxic fucoidan protected ARPE‑19 cells from high glucose‑induced cell death and normalized high glucose‑induced generation of ROS. Fucoidan also inhibited high glucose‑induced cell apoptosis, as well as the Ca2+ influx and ERK1/2 phosphorylation in ARPE‑19 cells. Taken together, these findings indicated that fucoidan protects ARPE‑19 cells against high glucose‑induced oxidative damage via normalization of ROS generation through the Ca2+‑dependent ERK signaling pathway. PMID:25606812

  10. Magnetic super-hydrophilic carbon nanotubes/graphene oxide composite as nanocarriers of mesenchymal stem cells: Insights into the time and dose dependences.

    Science.gov (United States)

    Granato, Alessandro E C; Rodrigues, Bruno V M; Rodrigues-Junior, Dorival M; Marciano, Fernanda R; Lobo, Anderson O; Porcionatto, Marimelia A

    2016-10-01

    Among nanostructured materials, multi-walled carbon nanotubes (MWCNT) have demonstrated great potential for biomedical applications in recent years. After oxygen plasma etching, we can obtain super-hydrophilic MWCNT that contain graphene oxide (GO) at their tips. This material exhibits good dispersion in biological systems due to the presence of polar groups and its excellent magnetic properties due to metal particle residues from the catalyst that often remain trapped in its walls and tips. Here, we show for the first time a careful biological investigation using magnetic superhydrophilic MWCNT/GO (GCN composites). The objective of this study was to investigate the application of GCN for the in vitro immobilization of mesenchymal stem cells. Our ultimate goal was to develop a system to deliver mesenchymal stem cells to different tissues and organs. We show here that mesenchymal stem cells were able to internalize GCN with a consequent migration when subjected to a magnetic field. The cytotoxicity of GCN was time- and dose-dependent. We also observed that GCN internalization caused changes in the gene expression of the proteins involved in cell adhesion and migration, such as integrins, laminins, and the chemokine CXCL12, as well as its receptor CXCR4. These results suggest that GCN represents a potential new platform for mesenchymal stem cell immobilization at injury sites. PMID:27287169

  11. Determination of glass transition temperature of reduced graphene oxide-poly(vinyl alcohol) composites using temperature dependent Fourier transform infrared spectroscopy

    Science.gov (United States)

    Mahendia, Suman; Heena; Kandhol, Geeta; Deshpande, Uday P.; Kumar, Shyam

    2016-05-01

    In the present work, structural properties of reduced graphene oxide (RGO) synthesized using modified Hummer's method and its composites with Poly(vinyl alcohol) (PVA) fabricated using solution-cast method have been studied. The structural properties of prepared samples have been systematically studied through UV-Visible absorption, Raman, Fourier Transform Infrared (FTIR) and Differential Scanning Calorimeter (DSC) spectroscopy. Infrared spectroscopy indicates the grafting of PVA chains with graphene layer through the formation of H-bonding linkage in the composites. Temperature-dependent FTIR spectra of PVA-RGO composite films were recorded to obtain the glass transition temperature (Tg) and to study its molecular origin. From these spectra the values of Tg were obtained using two-dimensional (2D) mapping of the first derivative of the absorbance intensity with respect to temperature (dA/dT), over the space of wavenumber and temperature. The value of Tg obtained for pure PVA increases from 78 °C to 92 °C after loading 0.5 wt.% of RGO in PVA and can be attributed to the strong H-bonding interaction between polymer chains and grafted solid surface of RGO. These results are in good agreement with those obtained from DSC analysis. This clearly indicates that the thermal behavior of PVA gets modified with loading of RGO.

  12. The dependence of the discharge of nitrous oxide by ordinary chernozem steppe of the Central-Chernozem Region of Russia from the content of humus, nitrogen and enzymatic activity

    Science.gov (United States)

    Avksentev, Alexey; Negrobova, Elena; Kramareva, Tatiana; Moiseeva, Evgenya

    2016-04-01

    The dependence of the discharge of nitrous oxide by ordinary chernozem steppe of the Central-Chernozem Region of Russia from the content of humus, nitrogen and enzymatic activity Alexey Avksentev, Elena Negrobova, Tatiana Kramareva, Evgenya Moiseeva 394000 Voronezh, Universitetskaya square, 1 Voronezh State University Nitrous oxide is emitted by soil as a result of microbiological processes, ranks third in the list of aggressive greenhouse gas after carbon dioxide and methane. Nitrous oxide is formed during nitrification and denitrification of ammonia that enters the soil during microbial decomposition of complex organic compounds. Denitrification can be direct and indirect. In the microbiological process of recovery of nitrates involved of the organic substance. In aerobic conditions microorganisms denitrificator behave like normal saprotrophs and oxidize organic matter in the act of breathing oxygen. Thus, they operate at different times two enzyme systems: the electron transport chain with an oxygen acceptor in aerobic and restoration of nitrates under anaerobic conditions. Investigation of the emission of nitrous oxide by ordinary Chernozem steppe of the Central-Chernozem Region showed that it depends on the type of cenosis and the content of available forms of nitrogen. Natural ecosystems emit nitrous oxide more than the soil of arable land. The dependence of the emission of nitrous oxide from the humus content shows positive trend, but the aggregation of data, significant differences are not detected. Research shows that nitrous oxide emissions are seasonal. So the autumn season is characterized by nitrous oxide emissions than spring. Enzymatic processes are an important link in the biological cycle of elements and, consequently, participate in the process of decomposition of organic matter, nitrification and other processes. Analysis of the data on enzyme activity of ordinary Chernozem and the intensity of emission of N20 shows a clear relationship between

  13. Activation of estrogen receptor β-dependent nitric oxide signaling mediates the hypotensive effects of estrogen in the rostral ventrolateral medulla of anesthetized rats

    Directory of Open Access Journals (Sweden)

    Shih Cheng-Dean

    2009-07-01

    Full Text Available Abstract Background Apart from their well-known peripheral cardiovascular effects, emerging evidence indicates that estrogen acts as a modulator in the brain to regulate cardiovascular functions. The underlying mechanisms of estrogen in central cardiovascular regulation, however, are poorly understood. The present study investigated the cardiovascular effects of 17β-estradiol (E2β in the rostral ventrolateral medulla (RVLM, where sympathetic premotor neurons are located, and delineated the engagement of nitric oxide (NO in E2β-induced cardiovascular responses. Methods In male Sprague-Dawley rats maintained under propofol anesthesia, the changes of blood pressure, heart rate and sympathetic vasomotor tone after microinjection bilaterally into the RVLM of a synthetic estrogen, E2β were examined for at least 120 min. The involvement of ERα and/or ERβ subtypes was determined by microinjection of selective ERα or ERβ agonist into bilateral RVLM. Different NO synthase (NOS inhibitors were used to evaluate the involvement of differential of NOS isoforms in the cardiovascular effects of E2β. Results Bilateral microinjection of E2β (0.5, 1, or 5 pmol into the RVLM dose-dependently decreased systemic arterial pressure (SAP and the power density of the vasomotor components of SAP signals, our experimental index for sympathetic neurogenic vasomotor tone. These cardiovascular depressive effects of E2β (1 pmol were abolished by co-injection of ER antagonist ICI 182780 (0.25 or 0.5 pmol, but not a transcription inhibitor actinomycin D (10 nmol. Like E2β, microinjection bilaterally into the RVLM of a selective ERβ agonist 2,3-bis(4-hydroxyphenyl propionitrile (DPN, 1, 2, or 5 pmol induced significant decreases in these hemodynamic parameters in a dose-dependent manner. In contrast, the selective ERα agonist 1,3,5-tris(4-hydroxyphenyl-4-propyl-1H-pyrazole (5 pmol did not influence the same cardiovascular parameters. Co-administration bilaterally

  14. SoxR-dependent response to oxidative stress and virulence of Erwinia chrysanthemi: the key role of SufC, an orphan ABC ATPase.

    Science.gov (United States)

    Nachin, L; El Hassouni, M; Loiseau, L; Expert, D; Barras, F

    2001-02-01

    Erwinia chrysanthemi causes soft-rot disease in a great variety of plants. In addition to the depolymerizing activity of plant cell wall-degrading enzymes, iron acquisition and resistance to oxidative stress contribute greatly to the virulence of this pathogen. Here, we studied the pin10 locus originally thought to encode new virulence factors. The sequence analysis revealed six open reading frames that were homologous to the Escherichia coli sufA, sufB, sufC, sufD, sufS and sufE genes. Sequence similarity searching predicted that (i) SufA, SufB, SufD, SufS and SufE proteins are involved in iron metabolism and possibly in Fe-S cluster assembly; and (ii) SufC is an ATPase of an ABC transporter. The reverse transcription-polymerase chain reaction procedure showed that the sufABCDSE genes constitute an operon. Expression of a sufB:uidA fusion was found to be induced in iron-deficient growth conditions and to be repressed by the iron-sensing Fur repressor. Each of the six suf genes was inactivated by the insertion of a cassette generating a non-polar mutation. The intracellular iron level in the sufA, sufB, sufC, sufS and sufE mutants was higher than in the wild type, as assessed by increased sensitivity to the iron-activated antibiotic streptonigrin. In addition, inactivation of sufC and sufD led to increased sensitivity to paraquat. Virulence tests showed that sufA and sufC mutants exhibited reduced ability to cause maceration of chicory leaves, whereas a functional sufC gene was necessary for the bacteria to cause systemic invasion of Saintpaulia ionantha. The E. coli sufC homologue was inactivated by reverse genetic. This mutation was found to modify the soxR-dependent induction of soxS gene expression. We discuss the possibility that SufC is a versatile ATPase that can associate either with the other Suf proteins to form a Fe-S cluster-assembling machinery or with membrane proteins encoded elsewhere in the chromosome to form an Fe-S ABC exporter. Overall, these

  15. The Study of NADPH-Dependent Flavoenzyme-Catalyzed Reduction of Benzo[1,2-c]1,2,5-oxadiazole N-Oxides (Benzofuroxans

    Directory of Open Access Journals (Sweden)

    Jonas Šarlauskas

    2014-12-01

    Full Text Available The enzymatic reactivity of a series of benzo[1,2-c]1,2,5-oxadiazole N-oxides (benzofuroxans; BFXs towards mammalian single-electron transferring NADPH:cytochrome P-450 reductase (P-450R and two-electron (hydride transferring NAD(PH:quinone oxidoreductase (NQO1 was examined in this work. Since the =N+ (→OO− moiety of furoxan fragments of BFXs bears some similarity to the aromatic nitro-group, the reactivity of BFXs was compared to that of nitro-aromatic compounds (NACs whose reduction mechanisms by these and other related flavoenzymes have been extensively investigated. The reduction of BFXs by both P-450R and NQO1 was accompanied by O2 uptake, which was much lower than the NADPH oxidation rate; except for annelated BFXs, whose reduction was followed by the production of peroxide. In order to analyze the possible quantitative structure-activity relationships (QSARs of the enzymatic reactivity of the compounds, their electron-accepting potency and other reactivity indices were assessed by quantum mechanical methods. In P-450R-catalyzed reactions, both BFXs and NACs showed the same reactivity dependence on their electron-accepting potency which might be consistent with an “outer sphere” electron transfer mechanism. In NQO1-catalyzed two-electron (hydride transferring reactions, BFXs acted as more efficient substrates than NACs, and the reduction efficacy of BFXs by NQO1 was in general higher than by single-electron transferring P-450R. In NQO1-catalyzed reactions, QSARs obtained showed that the reduction efficacy of BFXs, as well as that of NACs, was determined by their electron-accepting potency and could be influenced by their binding mode in the active center of NQO1 and by their global softness as their electronic characteristic. The reductive conversion of benzofuroxan by both flavoenzymes yielded the same reduction product of benzofuroxan, 2,3-diaminophenazine, with the formation of o-benzoquinone dioxime as a putative primary

  16. Synthesis from separate oxide targets of high quality La2−xSrxCuO4 thin films and dependence with doping of their superconducting transition width

    International Nuclear Information System (INIS)

    A series of superconducting La2−xSrxCuO4 thin films, with 0.09 ≲ x ≲ 0.22, is grown over (100)SrTiO3 substrates by means of a novel pulsed laser deposition method devised to increase the homogeneity and control of doping. We employ two separate parent oxide targets that receive ablation shots at arbitrary computer-controlled relative rates, instead of the conventional procedure that uses a single target whose doping determines the one of the film. We characterize the films both through conventional techniques (XRD, SEM, AFM and EDX) and by measuring their superconducting transition with a high-sensitivity SQUID magnetometer. The latter allows one to determine not only their average critical temperatures T-bar c(x) but also their dispersions due to inhomogeneities, ΔTc(x). For T-bar c(x) we obtain the conventional parabolic law centered at x = 0.16, plus a Gaussian depression near x = 1/8 with a T-bar c-height of about 5 K and x-width about 0.03. For ΔTc(x) we obtain, for all the dopings, values among the lowest reported up to now for La2−xSrxCuO4. The ΔTc(x) dependence can be explained in terms of the unavoidable randomness of the positioning of the Sr ions (the so-called intrinsic chemical inhomogeneity) and a separate residual Tc-inhomogeneity contribution of the order of 0.5 K, this last associated with the samples’ structural inhomogeneities and films’ substrate. (paper)

  17. Fully Coupled Modeling of Burnup-Dependent (U1- y , Pu y )O2- x Mixed Oxide Fast Reactor Fuel Performance

    Science.gov (United States)

    Liu, Rong; Zhou, Wenzhong; Zhou, Wei

    2016-03-01

    During the fast reactor nuclear fuel fission reaction, fission gases accumulate and form pores with the increase of fuel burnup, which decreases the fuel thermal conductivity, leading to overheating of the fuel element. The diffusion of plutonium and oxygen with high temperature gradient is also one of the important fuel performance concerns as it will affect the fuel material properties, power distribution, and overall performance of the fuel pin. In order to investigate these important issues, the (U1- y Pu y )O2- x fuel pellet is studied by fully coupling thermal transport, deformation, oxygen diffusion, fission gas release and swelling, and plutonium redistribution to evaluate the effects on each other with burnup-dependent models, accounting for the evolution of fuel porosity. The approach was developed using self-defined multiphysics models based on the framework of COMSOL Multiphysics to manage the nonlinearities associated with fast reactor mixed oxide fuel performance analysis. The modeling results showed a consistent fuel performance comparable with the previous results. Burnup degrades the fuel thermal conductivity, resulting in a significant fuel temperature increase. The fission gas release increased rapidly first and then steadily with the burnup increase. The fuel porosity increased dramatically at the beginning of the burnup and then kept constant as the fission gas released to the fuel free volume, causing the fuel temperature to increase. Another important finding is that the deviation from stoichiometry of oxygen affects greatly not only the fuel properties, for example, thermal conductivity, but also the fuel performance, for example, temperature distribution, porosity evolution, grain size growth, fission gas release, deformation, and plutonium redistribution. Special attention needs to be paid to the deviation from stoichiometry of oxygen in fuel fabrication. Plutonium content will also affect the fuel material properties and performance

  18. Acute paraquat exposure determines dose-dependent oxidative injury of multiple organs and metabolic dysfunction in rats: impact on exercise tolerance.

    Science.gov (United States)

    Novaes, Rômulo D; Gonçalves, Reggiani V; Cupertino, Marli C; Santos, Eliziária C; Bigonha, Solange M; Fernandes, Geraldo J M; Maldonado, Izabel R S C; Natali, Antônio J

    2016-04-01

    This study investigated the pathological morphofunctional adaptations related to the imbalance of exercise tolerance triggered by paraquat (PQ) exposure in rats. The rats were randomized into four groups with eight animals each: (a) SAL (control): 0.5 ml of 0.9% NaCl solution; (b) PQ10: PQ 10 mg/kg; (c) PQ20: PQ 20 mg/kg; and (d) PQ30: PQ 30 mg/kg. Each group received a single injection of PQ. After 72 hours, the animals were subjected to an incremental aerobic running test until fatigue in order to determine exercise tolerance, blood glucose and lactate levels. After the next 24 h, lung, liver and skeletal muscle were collected for biometric, biochemical and morphological analyses. The animals exposed to PQ exhibited a significant anticipation of anaerobic metabolism during the incremental aerobic running test, a reduction in exercise tolerance and blood glucose levels as well as increased blood lactate levels during exercise compared to control animals. PQ exposure increased serum transaminase levels and reduced the glycogen contents in liver tissue and skeletal muscles. In the lung, the liver and the skeletal muscle, PQ exposure also increased the contents of malondialdehyde, protein carbonyl, 8-hydroxy-2'-deoxyguanosine, superoxide dismutase and catalase, as well as a structural remodelling compared to the control group. All these changes were dose-dependent. Reduced exercise tolerance after PQ exposure was potentially influenced by pathological remodelling of multiple organs, in which glycogen depletion in the liver and skeletal muscle and the imbalance of glucose metabolism coexist with the induction of lipid, protein and DNA oxidation, a destructive process not counteracted by the upregulation of endogenous antioxidant enzymes. PMID:27277193

  19. Ambient synthesis of high-quality ruthenium nanowires and the morphology-dependent electrocatalytic performance of platinum-decorated ruthenium nanowires and nanoparticles in the methanol oxidation reaction.

    Science.gov (United States)

    Koenigsmann, Christopher; Semple, Dara Bobb; Sutter, Eli; Tobierre, Sybil E; Wong, Stanislaus S

    2013-06-26

    We report for the first time (a) the synthesis of elemental ruthenium nanowires (Ru NWs), (b) a method for modifying their surfaces with platinum (Pt), and (c) the morphology-dependent methanol oxidation reaction (MOR) performance of high-quality Pt-modified Ru NW electrocatalysts. The synthesis of our elemental Ru NWs has been accomplished utilizing a template-based method under ambient conditions. As-prepared Ru NWs are crystalline and elementally pure, maintain electrochemical properties analogous to elemental Ru, and can be generated with average diameters ranging from 44 to 280 nm. We rationally examine the morphology-dependent performance of the Ru NWs by comparison with commercial Ru nanoparticle (NP)/carbon (C) systems after decorating the surfaces of these structures with Pt. We have demonstrated that the deposition of Pt onto the Ru NWs (Pt~Ru NWs) results in a unique hierarchical structure, wherein the deposited Pt exists as discrete clusters on the surface. By contrast, we find that the Pt-decorated commercial Ru NP/C (Pt~Ru NP/C) results in the formation of an alloy-type NP. The Pt~Ru NPs (0.61 A/mg of Pt) possess nearly 2-fold higher Pt mass activity than analogous Pt~Ru NW electrocatalysts (0.36 A/mg of Pt). On the basis of a long-term durability test, it is apparent that both catalysts undergo significant declines in performance, potentially resulting from aggregation and ripening in the case of Pt~Ru NP/C and the effects of catalyst poisoning in the Pt~Ru NWs. At the conclusion of the test, both catalysts maintain comparable performance, despite a slightly enhanced performance in Pt~Ru NP/C. In addition, the measured mass-normalized MOR activity of the Pt~Ru NWs (0.36 A/mg of Pt) was significantly enhanced as compared with supported elemental Pt (Pt NP/C, 0.09 A/mg of Pt) and alloy-type PtRu (PtRu NP/C, 0.24 A/mg of Pt) NPs, both serving as commercial standards. PMID:23742154

  20. Protein kinase A-dependent Neuronal Nitric Oxide Synthase Activation Mediates the Enhancement of Baroreflex Response by Adrenomedullin in the Nucleus Tractus Solitarii of Rats

    Directory of Open Access Journals (Sweden)

    Ho I-Chun

    2011-05-01

    Full Text Available Abstract Background Adrenomedullin (ADM exerts its biological functions through the receptor-mediated enzymatic mechanisms that involve protein kinase A (PKA, or neuronal nitric oxide synthase (nNOS. We previously demonstrated that the receptor-mediated cAMP/PKA pathway involves in ADM-enhanced baroreceptor reflex (BRR response. It remains unclear whether ADM may enhance BRR response via activation of nNOS-dependent mechanism in the nucleus tractus solitarii (NTS. Methods Intravenous injection of phenylephrine was administered to evoke the BRR before and at 10, 30, and 60 min after microinjection of the test agents into NTS of Sprague-Dawley rats. Western blotting analysis was used to measure the level and phosphorylation of proteins that involved in BRR-enhancing effects of ADM (0.2 pmol in NTS. The colocalization of PKA and nNOS was examined by immunohistochemical staining and observed with a laser confocal microscope. Results We found that ADM-induced enhancement of BRR response was blunted by microinjection of NPLA or Rp-8-Br-cGMP, a selective inhibitor of nNOS or protein kinase G (PKG respectively, into NTS. Western blot analysis further revealed that ADM induced an increase in the protein level of PKG-I which could be attenuated by co-microinjection with the ADM receptor antagonist ADM22-52 or NPLA. Moreover, we observed an increase in phosphorylation at Ser1416 of nNOS at 10, 30, and 60 min after intra-NTS administration of ADM. As such, nNOS/PKG signaling may also account for the enhancing effect of ADM on BRR response. Interestingly, biochemical evidence further showed that ADM-induced increase of nNOS phosphorylation was prevented by co-microinjection with Rp-8-Br-cAMP, a PKA inhibitor. The possibility of PKA-dependent nNOS activation was substantiated by immunohistochemical demonstration of co-localization of PKA and nNOS in putative NTS neurons. Conclusions The novel finding of this study is that the signal transduction cascade that

  1. Radiation-induced oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder by gamma rays and electron beams: A clear dependence of dose rate

    Science.gov (United States)

    Wang, Honglong; Xu, Lu; Hu, Jiangtao; Wang, Mouhua; Wu, Guozhong

    2015-10-01

    Oxidation is an important effect of irradiation on polyethylene in air. In this work, oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder (ca. 110 μm in diameter) induced by gamma rays (γ ray) and electron beams (EB) in air resulted in some large differences in properties, such as oxidative scission due to dose rate differences. However, other properties, such as surface wettability and thermal stability were not that greatly affected. The dose-rates used were 0.0019 kGy/s from a cobalt-60 gamma source and 92 kGy/s from an electron beam. The chemical structure, oxidation level, surface wettability and thermal stability of irradiated UHMWPE were analyzed by FT-IR, XPS, TGA and the static contact angle. Hydrophilic carboxyl and carbonyl groups were present on the surface of irradiated UHMWPE after irradiation in air, resulting in a decrease in the contact angle. After irradiation at 300 kGy, the gel content of the γ ray-irradiated UHMWPE samples decreased to almost zero, while that of EB irradiated UHMWPE decreased to 57%. For UHMWPE powder irradiated by gamma rays at lower doses, radiation-induced oxidation was complete and consistent with a simple theoretic estimation. Surface wettability was primarily affected by surface oxidation, and the oxidation level of UHMWPE could be easily predicted.

  2. Radiation-induced oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder by gamma rays and electron beams: A clear dependence of dose rate

    International Nuclear Information System (INIS)

    Oxidation is an important effect of irradiation on polyethylene in air. In this work, oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder (ca. 110 μm in diameter) induced by gamma rays (γ ray) and electron beams (EB) in air resulted in some large differences in properties, such as oxidative scission due to dose rate differences. However, other properties, such as surface wettability and thermal stability were not that greatly affected. The dose-rates used were 0.0019 kGy/s from a cobalt-60 gamma source and 92 kGy/s from an electron beam. The chemical structure, oxidation level, surface wettability and thermal stability of irradiated UHMWPE were analyzed by FT-IR, XPS, TGA and the static contact angle. Hydrophilic carboxyl and carbonyl groups were present on the surface of irradiated UHMWPE after irradiation in air, resulting in a decrease in the contact angle. After irradiation at 300 kGy, the gel content of the γ ray-irradiated UHMWPE samples decreased to almost zero, while that of EB irradiated UHMWPE decreased to 57%. For UHMWPE powder irradiated by gamma rays at lower doses, radiation-induced oxidation was complete and consistent with a simple theoretic estimation. Surface wettability was primarily affected by surface oxidation, and the oxidation level of UHMWPE could be easily predicted. - Highlights: • UHMWPE powder was irradiated by γ ray and EB in air with difference in dose rate. • Radiation oxidation was studied and compared experimentally and theoretically. • The dose rate has great effect on thickness of oxidation layer in UHMWPE powder

  3. Manganese(II) catalyzes the bicarbonate-dependent oxidation of amino acids by hydrogen peroxide and the amino acid-facilitated dismutation of hydrogen peroxide.

    OpenAIRE

    Berlett, B S; Chock, P B; Yim, M B; Stadtman, E. R.

    1990-01-01

    In bicarbonate/CO2 buffer, Mn(II) and Fe(II) catalyze the oxidation of amino acids by H2O2 and the dismutation of H2O2. As the Mn(II)/Fe(II) ratio is increased, the yield of carbonyl compounds per mole of leucine oxidized is essentially constant, but the ratio of alpha-ketoisocaproate to isovaleraldehyde formed increases, and the fraction of H2O2 converted to O2 increases. In the absence of Fe(II), the rate of Mn(II)-catalyzed leucine oxidation is directly proportional to the H2O2, Mn(II), an...

  4. Effect of α-lactalbumin and β-lactoglobulin on the oxidative stability of 10% fish oil-in-water emulsions depends on pH

    DEFF Research Database (Denmark)

    Horn, Anna Frisenfeldt; Wulff, Tune; Nielsen, Nina Skall;

    2013-01-01

    The objective of this study was to investigate the influence of pH on lipid oxidation and protein partitioning in 10% fish oil-in-water emulsions prepared with different whey protein isolates with varying ratios of α-lactalbumin and β-lactoglobulin. Results showed that an increase in pH increased...... lipid oxidation irrespective of the emulsifier used. At pH 4, lipid oxidation was not affected by the type of whey protein emulsifier used or the partitioning of proteins between the interface and the water phase. However, at pH 7 the emulsifier with the highest concentration of β...... protein components....

  5. Near interface traps in SiO2/4H-SiC metal-oxide-semiconductor field effect transistors monitored by temperature dependent gate current transient measurements

    Science.gov (United States)

    Fiorenza, Patrick; La Magna, Antonino; Vivona, Marilena; Roccaforte, Fabrizio

    2016-07-01

    This letter reports on the impact of gate oxide trapping states on the conduction mechanisms in SiO2/4H-SiC metal-oxide-semiconductor field effect transistors (MOSFETs). The phenomena were studied by gate current transient measurements, performed on n-channel MOSFETs operated in "gate-controlled-diode" configuration. The measurements revealed an anomalous non-steady conduction under negative bias (VG > |20 V|) through the SiO2/4H-SiC interface. The phenomenon was explained by the coexistence of a electron variable range hopping and a hole Fowler-Nordheim (FN) tunnelling. A semi-empirical modified FN model with a time-depended electric field is used to estimate the near interface traps in the gate oxide (Ntrap ˜ 2 × 1011 cm-2).

  6. Size-dependent cytotoxicity of Fe3O4 nanoparticles induced by biphasic regulation of oxidative stress in different human hepatoma cells

    Directory of Open Access Journals (Sweden)

    Xie Y

    2016-07-01

    Full Text Available Yuexia Xie,1,2,* Dejun Liu,3,* Chenlei Cai,1,* Xiaojing Chen,1 Yan Zhou,1 Liangliang Wu,1 Yongwei Sun,3 Huili Dai,1,2 Xianming Kong,1,2 Peifeng Liu1,2 1Central Laboratory, 2State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, 3Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: The application of Fe3O4 nanoparticles (NPs has made great progress in the diagnosis of disease and in the drug delivery system for cancer therapy, but the relative mecha­nisms of potential toxicity induced by Fe3O4 have not kept pace with its development in the application, which has hampered its further clinical application. In this article, we used two kinds of human hepatoma cell lines, SK-Hep-1 and Hep3B, to investigate the cytotoxic effects and the involved mechanisms of small Fe3O4 NPs with different diameters (6 nm, 9 nm, and 14 nm. Results showed that the size of NPs effectively influences the cytotoxicity of hepatoma cells: 6 nm Fe3O4 NPs exhibited negligible cytotoxicity and 9 nm Fe3O4 NPs affected cytotoxicity via cellular mitochondrial dysfunction and by inducing necrosis mediated through the mitochondria-dependent intracellular reactive oxygen species generation. Meanwhile, 14 nm Fe3O4 NPs induced cytotoxicity by impairing the integrity of plasma membrane and promoting massive lactate dehydrogenase leakage. These results explain the detailed mechanism of different diameters of small Fe3O4 NPs-induced cytotoxicity. We anticipate that this study will provide different insights into the cytotoxicity mechanism of Fe3O4 NPs, so as to make them safer to use in clinical application. Keywords: hepatoma cells, nanoparticles, cytotoxicity, mechanism, oxidative stress

  7. Nitric oxide inhibits neuroendocrine CaV1 L-channel gating via cGMP-dependent protein kinase in cell-attached patches of bovine chromaffin cells

    Science.gov (United States)

    Carabelli, Valentina; D'Ascenzo, Marcello; Carbone, Emilio; Grassi, Claudio

    2002-01-01

    Nitric oxide (NO) regulates the release of catecholamines from the adrenal medulla but the molecular targets of its action are not yet well identified. Here we show that the NO donor sodium nitroprusside (SNP, 200 μM) causes a marked depression of the single CaV1 L-channel activity in cell-attached patches of bovine chromaffin cells. SNP action was complete within 3-5 min of cell superfusion. In multichannel patches the open probability (NPo) decreased by ∼60 % between 0 and +20 mV. Averaged currents over a number of traces were proportionally reduced and showed no drastic changes to their time course. In single-channel patches the open probability (Po) at +10 mV decreased by the same amount as that of multichannel patches (∼61 %). Such a reduction was mainly associated with an increased probability of null sweeps and a prolongation of mean shut times, while first latency, mean open time and single-channel conductance were not significantly affected. Addition of the NO scavenger carboxy-PTIO or cell treatment with the guanylate cyclase inhibitor ODQ prevented the SNP-induced inhibition. 8-Bromo-cyclicGMP (8-Br-cGMP; 400 μM) mimicked the action of the NO donor and the protein kinase G blocker KT-5823 prevented this effect. The depressive action of SNP was preserved after blocking the cAMP-dependent up-regulatory pathway with the protein kinase A inhibitor H89. Similarly, the inhibitory action of 8-Br-cGMP proceeded regardless of the elevation of cAMP levels, suggesting that cGMP/PKG and cAMP/PKA act independently on L-channel gating. The inhibitory action of 8-Br-cGMP was also independent of the G protein-induced inhibition of L-channels mediated by purinergic and opiodergic autoreceptors. Since Ca2+ channels contribute critically to both the local production of NO and catecholamine release, the NO/PKG-mediated inhibition of neuroendocrine L-channels described here may represent an important autocrine signalling mechanism for controlling the rate of

  8. Nitric oxide inhibits neuroendocrine Ca(V)1 L-channel gating via cGMP-dependent protein kinase in cell-attached patches of bovine chromaffin cells.

    Science.gov (United States)

    Carabelli, Valentina; D'Ascenzo, Marcello; Carbone, Emilio; Grassi, Claudio

    2002-06-01

    Nitric oxide (NO) regulates the release of catecholamines from the adrenal medulla but the molecular targets of its action are not yet well identified. Here we show that the NO donor sodium nitroprusside (SNP, 200 microM) causes a marked depression of the single Ca(V)1 L-channel activity in cell-attached patches of bovine chromaffin cells. SNP action was complete within 3-5 min of cell superfusion. In multichannel patches the open probability (NP(o)) decreased by approximately 60 % between 0 and +20 mV. Averaged currents over a number of traces were proportionally reduced and showed no drastic changes to their time course. In single-channel patches the open probability (P(o)) at +10 mV decreased by the same amount as that of multichannel patches (approximately 61 %). Such a reduction was mainly associated with an increased probability of null sweeps and a prolongation of mean shut times, while first latency, mean open time and single-channel conductance were not significantly affected. Addition of the NO scavenger carboxy-PTIO or cell treatment with the guanylate cyclase inhibitor ODQ prevented the SNP-induced inhibition. 8-Bromo-cyclicGMP (8-Br-cGMP; 400 microM) mimicked the action of the NO donor and the protein kinase G blocker KT-5823 prevented this effect. The depressive action of SNP was preserved after blocking the cAMP-dependent up-regulatory pathway with the protein kinase A inhibitor H89. Similarly, the inhibitory action of 8-Br-cGMP proceeded regardless of the elevation of cAMP levels, suggesting that cGMP/PKG and cAMP/PKA act independently on L-channel gating. The inhibitory action of 8-Br-cGMP was also independent of the G protein-induced inhibition of L-channels mediated by purinergic and opiodergic autoreceptors. Since Ca(2+) channels contribute critically to both the local production of NO and catecholamine release, the NO/PKG-mediated inhibition of neuroendocrine L-channels described here may represent an important autocrine signalling mechanism

  9. Crocin Suppresses LPS-Stimulated Expression of Inducible Nitric Oxide Synthase by Upregulation of Heme Oxygenase-1 via Calcium/Calmodulin-Dependent Protein Kinase 4

    OpenAIRE

    Ji-Hee Kim; Ga-Young Park; Soo Young Bang; Sun Young Park; Soo-Kyung Bae; YoungHee Kim

    2014-01-01

    Crocin is a water-soluble carotenoid pigment that is primarily used in various cuisines as a seasoning and coloring agent, as well as in traditional medicines for the treatment of edema, fever, and hepatic disorder. In this study, we demonstrated that crocin markedly induces the expression of heme oxygenase-1 (HO-1) which leads to an anti-inflammatory response. Crocin inhibited inducible nitric oxide synthase (iNOS) expression and nitric oxide production via downregulation of nuclear factor k...

  10. Salmonella enterica Serovar Typhimurium-Dependent Regulation of Inducible Nitric Oxide Synthase Expression in Macrophages by Invasins SipB, SipC, and SipD and Effector SopE2

    OpenAIRE

    Cherayil, Bobby J.; McCormick, Beth A.; Bosley, Jacob

    2000-01-01

    When Salmonella enterica invades mammalian cells, it activates signals leading to increased expression of inflammatory mediators. One such mediator is nitric oxide (NO), which is produced under control of the enzyme inducible NO synthase (iNOS). Induction of iNOS in response to Salmonella infection has been demonstrated, but the bacterial effector molecules that regulate expression of the enzyme have not been identified. In the study reported here, an analysis of Salmonella-dependent iNOS exp...

  11. Ion exchange selectivity and kinetics on hydrous oxides and their dependence on their acidity, capacity, surface area, pore structure and crystallinity

    International Nuclear Information System (INIS)

    In the present work hydrous alumina, ferric oxide, ceria and tin oxide were prepared by different methods and subjected to X-ray, infra-red, thermal and porous texture analysis. Alkali cation and halide ion selectivity coefficients were measured under different conditions, and diffusion coefficients of Cs+ in two alumina samples and of Na+ in three iron oxide gels heated at different temperatures were determined by tracer diffusion. Besides, equilibrium distribution of U, Ce, La, Eu, Fe, Co, Ni, Sr, Ba, Na and Cs on ceria and tin oxide were measured under a variety of conditions. The results obtained in the present work have shown that OH groups and/or H2O molecules present on the surface of hydrous oxides act as the exchange sites. In the amorphous or microcrystalline samples, the OH groups start to condense at temperatures as low as 100 deg. C. The surface area is generally a poor factor in determining the ion exchange capacity. The kinetic studies have shown that ion mobility decreases with the decrease of pore size, increase of capacity, and decrease of site acidity. The latter two factors lead to the increase of the strength of interaction of the ion with the exchange sites. The equilibrium distribution measurements of several ions on ceria and tin oxide point to a possible use of both oxides in the separation of uranium from all the other elements and in the separation of elements or groups of elements from each other. In this respect, ceria seems to be more attractive

  12. Wiring of Glucose Oxidizing Flavin Adenine Dinucleotide-Dependent Enzymes by Methylene Blue-Modified Third Generation Poly(amidoamine) Dendrimers Attached to Spectroscopic Graphite Electrodes

    DEFF Research Database (Denmark)

    Castaing, Victor; Álvarez-Martos, Isabel; Ferapontova, Elena

    2016-01-01

    , characterized by the heterogeneous ET rate constant of 7.1 0.1 s1; they can be used for electronic wiring of glucose-oxidizing FAD-containing enzymes, such as hexose oxidase (HOX), and further bioelectrocatalysis of glucose oxidation, starting, at pH 7, from -100 mV vs. Ag/AgCl. Thus, dendrimer......-templated electronic wires, comprising MB molecules conjugated to the periphery of the PAMAM and anchored to the surface of cost-effective Gr electrodes represent an efficient and robust tool for protein wiring to electrodes for their perspective bioelectronic applications in biosensors and biofuel cells....

  13. Evaluation of the role of leptin, interleukin-8 (Il-8) and nitric oxide (No) in children with insulin dependent diabetes mellitus (type 1)

    International Nuclear Information System (INIS)

    The autoimmune nature of insulin dependent diabetes mellitus (IDDM), type 1, is well established. The documentation of altered Th 1/Th 2 balance and the finding of antibodies in the circulation directed against the b-cells can indicate the role of the immune system. The stimulating effect of insulin on leptin expression is well identified. The aim of this study is to investigate the profile and the relationships between leptin, interleukin-8 (IL-8) and nitric oxide (NO) and to reveal their possible role in the development and progression of IDDM. Serum leptin was evaluated using radioimmunoassay (RIA), serum concentration of IL-8 was assayed by enzyme linked immunosorbent assay (ELISA), while serum nitrite level (end product of NO) was determined by Griess reaction. The study was carried out on twenty IDDM children who compared with other twenty healthy non-diabetic ones with the same age and sex. The data revealed that children with IDDM established high weight-for-age (W/A)Z (P < 0.001) , high weight-for-height (W/H)Z (P < 0.05) and high glycated hemoglobin (HbA1c% ) (P < 0.0001). Both diabetic boys and girls showed higher serum leptin levels (7.48 ± 1.86 ng/ml) than the control group (5.92 ± 1.39 ng/ml). Leptin levels were higher in diabetic girls (8.46 ± 2.29 ng/ml) than diabetic boys (6.68 ± 0.91 ng/ml). Significant high level of serum IL-8 concentration (23 ± 11.92 pg/ml) was detected in IDDM children versus the control group (5.69 ± 1.67 pg/ml). On the other hand, serum nitrite values showed significant reduction in the IDDM children (430.78 ± 155.14 Μmol/l) compared to the control group (610.08 ± 192.82 Μmol/l). Correlation analysis showed positive correlation between leptin with age, (W/H)Z and fasting glucose level, furthermore, a positive correlation was established between IL-8 with (W/H)Z, hinting the adipose tissue as a site of its production and no association between NO and other relevant variables was detected. It could be concluded that

  14. The effect of oxide shell thickness on the structural, electronic, and optical properties of Si-SiO2 core-shell nano-crystals: A (time dependent)density functional theory study

    Science.gov (United States)

    Nazemi, Sanaz; Pourfath, Mahdi; Soleimani, Ebrahim Asl; Kosina, Hans

    2016-04-01

    Due to their tunable properties, silicon nano-crystals (NC) are currently being investigated. Quantum confinement can generally be employed for size-dependent band-gap tuning at dimensions smaller than the Bohr radius (˜5 nm for silicon). At the nano-meter scale, however, increased surface-to-volume ratio makes the surface effects dominant. Specifically, in Si-SiO2 core-shell semiconductor NCs the interfacial transition layer causes peculiar electronic and optical properties, because of the co-existence of intermediate oxidation states of silicon (Sin+, n = 0-4). Due to the presence of the many factors involved, a comprehensive understanding of the optical properties of these NCs has not yet been achieved. In this work, Si-SiO2 NCs with a diameter of 1.1 nm and covered by amorphous oxide shells with thicknesses between 2.5 and 4.75 Å are comprehensively studied, employing density functional theory calculations. It is shown that with increased oxide shell thickness, the low-energy part of the optical transition spectrum of the NC is red shifted and attenuated. Moreover, the absorption coefficient is increased in the high-energy part of the spectrum which corresponds to SiO2 transitions. Structural examinations indicate a larger compressive stress on the central silicon cluster with a thicker oxide shell. Examination of the local density of states reveals the migration of frontier molecular orbitals from the oxide shell into the silicon core with the increase of silica shell thickness. The optical and electrical properties are explained through the analysis of the density of states and the spatial distribution of silicon sub-oxide species.

  15. Distributive Processing by the Iron(II)/α-Ketoglutarate-Dependent Catalytic Domains of the TET Enzymes Is Consistent with Epigenetic Roles for Oxidized 5-Methylcytosine Bases.

    Science.gov (United States)

    Tamanaha, Esta; Guan, Shengxi; Marks, Katherine; Saleh, Lana

    2016-08-01

    The ten-eleven translocation (TET) proteins catalyze oxidation of 5-methylcytosine ((5m)C) residues in nucleic acids to 5-hydroxymethylcytosine ((5hm)C), 5-formylcytosine ((5f)C), and 5-carboxycytosine ((5ca)C). These nucleotide bases have been implicated as intermediates on the path to active demethylation, but recent reports have suggested that they might have specific regulatory roles in their own right. In this study, we present kinetic evidence showing that the catalytic domains (CDs) of TET2 and TET1 from mouse and their homologue from Naegleria gruberi, the full-length protein NgTET1, are distributive in both chemical and physical senses, as they carry out successive oxidations of a single (5m)C and multiple (5m)C residues along a polymethylated DNA substrate. We present data showing that the enzyme neither retains (5hm)C/(5f)C intermediates of preceding oxidations nor slides along a DNA substrate (without releasing it) to process an adjacent (5m)C residue. These findings contradict a recent report by Crawford et al. ( J. Am. Chem. Soc. 2016 , 138 , 730 ) claiming that oxidation of (5m)C by CD of mouse TET2 is chemically processive (iterative). We further elaborate that this distributive mechanism is maintained for TETs in two evolutionarily distant homologues and posit that this mode of function allows the introduction of (5m)C forms as epigenetic markers along the DNA. PMID:27362828

  16. Exceptional performance of photoelectrochemical water oxidation of single-crystal rutile TiO2 nanorods dependent on the hole trapping of modified chloride

    Science.gov (United States)

    Zhang, Xuliang; Cui, Haiqin; Humayun, Muhammad; Qu, Yang; Fan, Naiying; Sun, Xiaojun; Jing, Liqiang

    2016-02-01

    It is highly desired to effectively trap photogenerated holes for efficient photoelectrochemical (PEC) water oxidation to evolve O2 on oxide semiconductors. Herein, it is found for the first time mainly based on the time-resolved- and atmosphere-controlled- surface photovoltage responses that the modified chloride would effectively trap photogenerated holes so as to prolong the charge lifetime and hence promote charge separation of single-crystal rutile TiO2 nanorods. Its strong capacity to trap holes, comparable to the widely-used methanol and Co(II) phosphate, is well responsible for the exceptional photoactivities for PEC water oxidation to evolve O2 on rutile nanorods with a proper amount of chloride modified, about 2.5-time high as that on the resulting anatase nanoparticles, even 10-time if the surface area is considered. Moreover, it is suggested that the hole trapping role of chemically-adsorbed chloride is related to its lonely-pair electrons, and to the subsequently-produced intermediate Cl atoms with proper electronegativity for evolving O2. Interestingly, this finding is also applicable to the chloride-modified anatase TiO2. This work will provide a feasible strategy to design high-activity nanostructured semiconductor photoanodes for PEC water oxidation, even for overall water splitting.

  17. Influence of calcium-dependent potassium channel blockade and nitric oxide inhibition on norepinephrine-induced contractions in two forms of genetic hypertension

    Czech Academy of Sciences Publication Activity Database

    Líšková, Silvia; Petrová, M.; Karen, Petr; Kuneš, Jaroslav; Zicha, Josef

    2010-01-01

    Roč. 4, č. 3 (2010), s. 128-134. ISSN 1933-1711 R&D Projects: GA AV ČR(CZ) IAA500110902 Institutional research plan: CEZ:AV0Z50110509 Keywords : potassium channels * nitric oxide * norepinephrine Subject RIV: ED - Physiology Impact factor: 0.931, year: 2010

  18. Melatonin prevents the dynamin-related protein 1-dependent mitochondrial fission and oxidative insult in the cortical neurons after 1-methyl-4-phenylpyridinium treatment.

    Science.gov (United States)

    Chuang, Jih-Ing; Pan, I-Ling; Hsieh, Chia-Yun; Huang, Chiu-Ying; Chen, Pei-Chun; Shin, Jyh Wei

    2016-09-01

    Mitochondrial dysfunction and oxidative stress are involved in the pathogenesis of Parkinson's disease (PD). Mitochondrial morphology is dynamic and precisely regulated by the mitochondrial fission and fusion machinery. Aberrant mitochondrial fragmentation controlled by the mitochondrial fission protein, dynamin-related protein 1 (Drp1), may result in cell death. Our previous results showed that melatonin protected neurons by inhibiting oxidative stress in a 1-methyl-4-phenylpyridinium (MPP(+) )-induced PD model. However, the effect of melatonin on mitochondrial dynamics remains uncharacterized. Herein, we investigated the effect of melatonin and the role of Drp1 on MPP(+) -induced mitochondrial fission in rat primary cortical neurons. We found that MPP(+) induced a rapid increase in the ratio of GSSG:total glutathione (a marker of oxidative stress) and mitochondrial fragmentation, Drp1 upregulation within 4 hours, and finally resulted in neuron loss 48 hours after the treatment. Neurons overexpressing wild-type Drp1 promoted mitochondrial and nuclear fragmentation; however, neurons overexpressing dominant-negative Drp1(K38A) or cotreated with melatonin exhibited significantly reduced MPP(+) -induced mitochondrial fragmentation and neuron death. Moreover, melatonin cotreatment prevented an MPP(+) -induced high ratio of GSSG and mitochondrial Drp1 upregulation. The prevention of mitochondrial fission by melatonin was not found in neurons transfected with wild-type Drp1. These results provide a new insight that the neuroprotective effect of melatonin against MPP(+) toxicity is mediated by inhibiting the oxidative stress and Drp1-mediated mitochondrial fragmentation. PMID:27159033

  19. Sublethal Pb exposure produces season-dependent effects on immune response, oxidative balance and investment in carotenoid-based coloration in red-legged partridges.

    Science.gov (United States)

    Vallverdú-Coll, Núria; Ortiz-Santaliestra, Manuel E; Mougeot, François; Vidal, Dolors; Mateo, Rafael

    2015-03-17

    Ingestion of lead (Pb) shot pellets constitutes the main cause of Pb poisoning in avifauna. We studied the effects of sublethal Pb exposure on immunity, carotenoid-based coloration, oxidative stress and trade-offs among these types of responses during spring and autumn in red-legged partridges (Alectoris rufa). We evaluated constitutive immunity testing lysozyme and natural antibody levels, and blood bactericidal and phagocytic activities. We studied induced immunity by testing PHA and humoral responses. We analyzed fecal parasite and bacterial abundance and oxidative stress biomarkers. Pb exposure in spring reduced natural antibody levels, whereas in autumn, it reduced lysozyme levels and increased phagocytic activity. Pb exposure increased PHA response in both seasons, and decreased T-independent humoral response in autumn. Pb exposure also increased noncoliform and decreased coliform Gram-negative gut bacteria. In spring, Pb exposure decreased antioxidant levels and increased coloration in males, whereas in autumn, it increased retinol levels but reduced coloration in both genders. Our results suggest that in spring, Pb-exposed females used antioxidants to cope with oxidative stress at the expense of coloration, whereas Pb-exposed males increased coloration, which may reflect an increased breeding investment. In autumn, both genders prioritized oxidative balance maintenance at the expense of coloration. PMID:25674808

  20. Wiring of Glucose Oxidizing Flavin Adenine Dinucleotide-Dependent Enzymes by Methylene Blue-Modified Third Generation Poly(amidoamine) Dendrimers Attached to Spectroscopic Graphite Electrodes

    DEFF Research Database (Denmark)

    Castaing, Victor; Álvarez-Martos, Isabel; Ferapontova, Elena

    2016-01-01

    ordered multiple redox centers, represent an advanced alternative to the existing approaches. Here we show that methylene blue (MB)-labeled G3 PAMAM dendrimers covalently attached to the high-surface area spectroscopic graphite (Gr) electrodes form stable and spatially resolved electronic wires......, characterized by the heterogeneous ET rate constant of 7.1 0.1 s1; they can be used for electronic wiring of glucose-oxidizing FAD-containing enzymes, such as hexose oxidase (HOX), and further bioelectrocatalysis of glucose oxidation, starting, at pH 7, from -100 mV vs. Ag/AgCl. Thus, dendrimer......-templated electronic wires, comprising MB molecules conjugated to the periphery of the PAMAM and anchored to the surface of cost-effective Gr electrodes represent an efficient and robust tool for protein wiring to electrodes for their perspective bioelectronic applications in biosensors and biofuel cells....

  1. Oxidative stress-dependent activation of collagen synthesis is induced in human pulmonary smooth muscle cells by sera from patients with scleroderma-associated pulmonary hypertension

    OpenAIRE

    Boin, Francesco; Erre, Gian Luca; Posadino, Anna Maria; Cossu, Annalisa; Giordo, Roberta; Spinetti, Gaia; Passiu, Giuseppe; Emanueli, Costanza; PINTUS, GIANFRANCO

    2014-01-01

    Pulmonary arterial hypertension is a major complication of systemic sclerosis. Although oxidative stress, intima hyperplasia and a progressive vessel occlusion appear to be clearly involved, the fine molecular mechanisms underpinning the onset and progression of systemic sclerosis-associated pulmonary arterial hypertension remain largely unknown. Here we shows for the first time that an increase of NADPH-derived reactive oxygen species production induced by sera from systemic sclerosis patien...

  2. A factorial randomized controlled trial to evaluate the effect of micronutrients supplementation and regular aerobic exercise on maternal endothelium-dependent vasodilatation and oxidative stress of the newborn

    OpenAIRE

    Girón Sandra; Salazar Blanca; Mosquera Mildrey; Ortega José; Echeverri Isabella; Romero Miryam; Ramírez-Vélez Robinson; Saldarriaga Wilmar; Aguilar de Plata Ana; Mateus Julio

    2011-01-01

    Abstract Background Many studies have suggested a relationship between metabolic abnormalities and impaired fetal growth with the development of non-transmissible chronic diseases in the adulthood. Moreover, it has been proposed that maternal factors such as endothelial function and oxidative stress are key mechanisms of both fetal metabolic alterations and subsequent development of non-transmissible chronic diseases. The objective of this project is to evaluate the effect of micronutrient su...

  3. Differential effects of quercetin on hippocampus-dependent learning and memory in mice fed with different diets related with oxidative stress.

    Science.gov (United States)

    Xia, Shu-Fang; Xie, Zhen-Xing; Qiao, Yi; Li, Li-Rong; Cheng, Xiang-Rong; Tang, Xue; Shi, Yong-Hui; Le, Guo-Wei

    2015-01-01

    High fat diets induce oxidative stress which may be involved in neurodegenerative diseases. Quercetin is a kind of antioxidant that has neuroprotective effects and potent7ial pro-oxidant effects as well. In this study, we evaluated cognitive function in mice fed with high fat diets and basic diets with or without quercetin. Male Chinese Kunming (KM) mice were randomly assigned to five groups fed with basic diet (Control), basic diet with 0.005% (w/w) quercetin (CQ1), high fat diet (HFD), HFD with 0.005% (w/w) quercetin (HFDQ1) and 0.01% (w/w) quercetin (HFDQ2) for 13weeks. At the end of the study period, fasting blood glucose (FBG), plasma and hippocampal markers of oxidative stress, plasma lipid status, Morris water maze as well as hippocampal relative mRNA expression of akt, bdnf, camkII, creb, gsk-3β, nrf2 and pi3k were examined. The results suggested that in comparison to the control group, the escape latency was increased and percent time spent in the target quadrant was decreased, with increased reactive carbonyls, malondialdehyde (MDA) and declined expression of pi3k, akt, nrf2, creb and bdnf in the hippocampus of HFD and CQ1 groups. Conversely, higher quercetin supplemented to HFD improved antioxidant capacity and reversed cognitive decline completely. Significant correlations between the redox status and cognition-related gene expression were observed as well (Pcognition. But under a balanced situation, quercetin exerts pro-oxidant effects to impair cognition. PMID:25447470

  4. The oxidant and laser power-dependent plasmon-driven surface photocatalysis reaction of p-aminothiophenol dimerizing into p,p'-dimercaptoazobenzene on Au nanoparticles.

    Science.gov (United States)

    Tan, Enzhong; Yin, Penggang; Yu, Chunna; Yu, Ge; Zhao, Chang

    2016-09-01

    Recently, plasmon-driven surface photocatalysis (PDSPC) reactions have attracted more and more attention by means of surface-enhanced Raman scattering (SERS) because we can in situ monitor the reaction process and determine the final products and their quantities by the real-time SERS spectrum. In this work, self-assembly AuNPs with both high catalytic activity and strong SERS effect were used as a bifunctional platform for in situ monitoring of PDSPC reactions. p-Aminothiophenol (PATP), a famous model molecule, was selected as a probe molecule and FeCl3 and NaClO were selected as oxidants. In this way, oxidation reaction of PATP dimerizing into p,p'-dimercaptoazobenzene (DMAB) has been investigated by SERS, and the results show that oxidant and laser power can alter the conversion rate of the reaction. This work provides a novel approach for controlling PDSPC reaction rate, which may be useful for understanding the mechanism of PDSPC reactions. PMID:27179296

  5. miR-155-dependent regulation of mammalian sterile 20-like kinase 2 (MST2) coordinates inflammation, oxidative stress and proliferation in vascular smooth muscle cells.

    Science.gov (United States)

    Yang, Zhan; Zheng, Bin; Zhang, Yu; He, Ming; Zhang, Xin-hua; Ma, Dong; Zhang, Ruo-nan; Wu, Xiao-li; Wen, Jin-kun

    2015-07-01

    In response to vascular injury, inflammation, oxidative stress, and cell proliferation often occur simultaneously in vascular tissues. We previously observed that microRNA-155 (miR-155), which is implicated in proliferation and inflammation is involved in neointimal hyperplasia; however, the molecular mechanisms by which it regulates these processes remain largely unknown. In this study, we observed that vascular smooth muscle cell (VSMC) proliferation and neointimal formation in wire-injured femoral arteries were reduced by the loss of miR-155 and increased by the gain of miR-155. The proliferative effect of miR-155 was also observed in cultured VSMCs. Notably, expression of the miR-155-target protein mammalian sterile 20-like kinase 2 (MST2) was increased in the injured arteries of miR-155-/- mice. miR-155 directly repressed MST2 and thus activated the extracellular signal-regulated kinase (ERK) pathway by promoting an interaction between RAF proto-oncogene serine/threonine-protein kinase (Raf-1) and mitogen-activated protein kinase kinase (MEK) and stimulating inflammatory and oxidative stress responses; together, these effects lead to VSMC proliferation and vascular remodeling. Our data reveal that MST2 mediates miR-155-promoted inflammatory and oxidative stress responses by altering the interaction of MEK with Raf-1 and MST2 in response to vascular injury. Therefore, suppression of endogenous miR-155 might be a novel therapeutic strategy for vascular injury and remodeling. PMID:25892184

  6. Expression of the tetrahydrofolate-dependent nitric oxide synthase from the green alga Ostreococcus tauri increases tolerance to abiotic stresses and influences stomatal development in Arabidopsis.

    Science.gov (United States)

    Foresi, Noelia; Mayta, Martín L; Lodeyro, Anabella F; Scuffi, Denise; Correa-Aragunde, Natalia; García-Mata, Carlos; Casalongué, Claudia; Carrillo, Néstor; Lamattina, Lorenzo

    2015-06-01

    Nitric oxide (NO) is a signaling molecule with diverse biological functions in plants. NO plays a crucial role in growth and development, from germination to senescence, and is also involved in plant responses to biotic and abiotic stresses. In animals, NO is synthesized by well-described nitric oxide synthase (NOS) enzymes. NOS activity has also been detected in higher plants, but no gene encoding an NOS protein, or the enzymes required for synthesis of tetrahydrobiopterin, an essential cofactor of mammalian NOS activity, have been identified so far. Recently, an NOS gene from the unicellular marine alga Ostreococcus tauri (OtNOS) has been discovered and characterized. Arabidopsis thaliana plants were transformed with OtNOS under the control of the inducible short promoter fragment (SPF) of the sunflower (Helianthus annuus) Hahb-4 gene, which responds to abiotic stresses and abscisic acid. Transgenic plants expressing OtNOS accumulated higher NO concentrations compared with siblings transformed with the empty vector, and displayed enhanced salt, drought and oxidative stress tolerance. Moreover, transgenic OtNOS lines exhibited increased stomatal development compared with plants transformed with the empty vector. Both in vitro and in vivo experiments indicate that OtNOS, unlike mammalian NOS, efficiently uses tetrahydrofolate as a cofactor in Arabidopsis plants. The modulation of NO production to alleviate abiotic stress disturbances in higher plants highlights the potential of genetic manipulation to influence NO metabolism as a tool to improve plant fitness under adverse growth conditions. PMID:25880454

  7. The oxidant and laser power-dependent plasmon-driven surface photocatalysis reaction of p-aminothiophenol dimerizing into p,p‧-dimercaptoazobenzene on Au nanoparticles

    Science.gov (United States)

    Tan, Enzhong; Yin, Penggang; Yu, Chunna; Yu, Ge; Zhao, Chang

    2016-09-01

    Recently, plasmon-driven surface photocatalysis (PDSPC) reactions have attracted more and more attention by means of surface-enhanced Raman scattering (SERS) because we can in situ monitor the reaction process and determine the final products and their quantities by the real-time SERS spectrum. In this work, self-assembly AuNPs with both high catalytic activity and strong SERS effect were used as a bifunctional platform for in situ monitoring of PDSPC reactions. p-Aminothiophenol (PATP), a famous model molecule, was selected as a probe molecule and FeCl3 and NaClO were selected as oxidants. In this way, oxidation reaction of PATP dimerizing into p,p‧-dimercaptoazobenzene (DMAB) has been investigated by SERS, and the results show that oxidant and laser power can alter the conversion rate of the reaction. This work provides a novel approach for controlling PDSPC reaction rate, which may be useful for understanding the mechanism of PDSPC reactions.

  8. Ethanol Extract of Cirsium japonicum var. ussuriense Kitamura Exhibits the Activation of Nuclear Factor Erythroid 2-Related Factor 2-dependent Antioxidant Response Element and Protects Human Keratinocyte HaCaT Cells Against Oxidative DNA Damage

    Science.gov (United States)

    Yoo, Ok-Kyung; Choi, Bu Young; Park, Jin-Oh; Lee, Ji-Won; Park, Byoung-Kwon; Joo, Chul Gue; Heo, Hyo-Jung; Keum, Young-Sam

    2016-01-01

    Keratinocytes are constantly exposed to extracellular insults, such as ultraviolet B, toxic chemicals and mechanical stress, all of which can facilitate the aging of keratinocytes via the generation of intracellular reactive oxygen species (ROS). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that plays a critical role in protecting keratinocytes against oxidants and xenobiotics by binding to the antioxidant response element (ARE), a cis-acting element existing in the promoter of most phase II cytoprotective genes. In the present study, we have attempted to find novel ethanol extract(s) of indigenous plants of Jeju island, Korea that can activate the Nrf2/ARE-dependent gene expression in human keratinocyte HaCaT cells. As a result, we identified that ethanol extract of Cirsium japonicum var. ussuriense Kitamura (ECJUK) elicited strong stimulatory effect on the ARE-dependent gene expression. Supporting this observation, we found that ECJUK induced the expression of Nrf2, hemoxygenase-1, and NAD(P)H:quinone oxidoreductase-1 and this event was correlated with Akt1 phosphorylation. We also found that ECJUK increased the intracellular reduced glutathione level and suppressed 12-O-tetradecanoylphorbol acetate-induced 8-hydroxyguanosine formation without affecting the overall viability. Collectively, our results provide evidence that ECJUK can protect against oxidative stress-mediated damages through the activation of Nrf2/ARE-dependent phase II cytoprotective gene expression. PMID:27051652

  9. Temperature-dependent effects of cadmium and purine nucleotides on mitochondrial aconitase from a marine ectotherm, Crassostrea virginica: a role of temperature in oxidative stress and allosteric enzyme regulation.

    Science.gov (United States)

    Cherkasov, Anton A; Overton, Robert A; Sokolov, Eugene P; Sokolova, Inna M

    2007-01-01

    Temperature and heavy metals such as cadmium (Cd) are important environmental stressors that can strongly affect mitochondrial function of marine poikilotherms. In this study, we investigated the combined effects of temperature (20 degrees C and 30 degrees C) and Cd stress on production of reactive oxygen species (ROS) and oxidative stress in a marine poikilotherm Crassostrea virginica (the eastern oyster) using mitochondrial aconitase as a sensitive biomarker of oxidative damage. We also assessed potential involvement of mitochondrial uncoupling proteins (UCPs) in antioxidant protection in oyster mitochondria using purine nucleotides (GDP, ATP and ADP) as specific inhibitors, and free fatty acids as stimulators, of UCPs. Our results show that exposure to Cd results in elevated ROS production and oxidative damage as indicated by aconitase inactivation which is particularly pronounced at elevated temperature. Unexpectedly, oyster mitochondrial aconitase was inhibited by physiologically relevant levels of ATP (IC(50)=1.93 and 3.04 mmol l(-1) at 20 degrees C and 30 degrees C, respectively), suggesting that allosteric regulation of aconitase by this nucleotide may be involved in regulation of the tricarboxylic acid flux in oysters. Aconitase was less sensitive to ATP inhibition at 30 degrees C than at 20 degrees C, consistent with the elevated metabolic flux at higher temperatures. ADP and GDP also inhibited mitochondrial aconitase but at the levels well above the physiological concentrations of these nucleotides (6-11 mmol l(-1)). Our study shows expression of at least three UCP isoforms in C. virginica gill tissues but provides no indication that UCPs protect mitochondrial aconitase from oxidative inactivation in oysters. Overall, the results of this study indicate that temperature stress exaggerates toxicity of Cd leading to elevated oxidative stress in mitochondria, which may have important implications for survival of poikilotherms in polluted environments during

  10. High Glucose Inhibits the Aspirin-Induced Activation of the Nitric Oxide/cGMP/cGMP-Dependent Protein Kinase Pathway and Does Not Affect the Aspirin-Induced Inhibition of Thromboxane Synthesis in Human Platelets

    OpenAIRE

    Russo, Isabella; Viretto, Michela; Barale, Cristina; Mattiello, Luigi; Doronzo, Gabriella; Pagliarino, Andrea; Cavalot, Franco; Trovati, Mariella; Anfossi, Giovanni

    2012-01-01

    Since hyperglycemia is involved in the “aspirin resistance” occurring in diabetes, we aimed at evaluating whether high glucose interferes with the aspirin-induced inhibition of thromboxane synthesis and/or activation of the nitric oxide (NO)/cGMP/cGMP-dependent protein kinase (PKG) pathway in platelets. For this purpose, in platelets from 60 healthy volunteers incubated for 60 min with 5–25 mmol/L d-glucose or iso-osmolar mannitol, we evaluated the influence of a 30-min incubation with lysine...

  11. Multidrug Resistance-associated Protein-1 (MRP-1)-dependent Glutathione Disulfide (GSSG) Efflux as a Critical Survival Factor for Oxidant-enriched Tumorigenic Endothelial Cells.

    Science.gov (United States)

    Gordillo, Gayle M; Biswas, Ayan; Khanna, Savita; Spieldenner, James M; Pan, Xueliang; Sen, Chandan K

    2016-05-01

    Endothelial cell tumors are the most common soft tissue tumors in infants. Tumor-forming endothelial (EOMA) cells are able to escape cell death fate despite excessive nuclear oxidant burden. Our previous work recognized perinuclear Nox-4 as a key contributor to EOMA growth. The objective of this work was to characterize the mechanisms by which EOMA cells evade oxidant toxicity and thrive. In EOMA cells, compared with in the cytosol, the nuclear GSSG/GSH ratio was 5-fold higher. Compared to the ratio observed in healthy murine aortic endothelial (MAE) cells, GSSG/GSH was over twice as high in EOMA cells. Multidrug resistance-associated protein-1 (MRP-1), an active GSSG efflux mechanism, showed 2-fold increased activity in EOMA compared with MAE cells. Hyperactive YB-1 and Ape/Ref-1 were responsible for high MRP-1 expression in EOMA. Proximity ligand assay demonstrated MRP-1 and YB-1 binding. Such binding enabled the nuclear targeting of MRP-1 in EOMA in a leptomycin-B-sensitive manner. MRP-1 inhibition as well as knockdown trapped nuclear GSSG, causing cell death of EOMA. Disulfide loading of cells by inhibition of GSSG reductase (bischoloronitrosourea) or thioredoxin reductase (auranofin) was effective in causing EOMA death as well. In sum, EOMA cells survive a heavy oxidant burden by rapid efflux of GSSG, which is lethal if trapped within the cell. A hyperactive MRP-1 system for GSSG efflux acts as a critical survival factor for these cells, making it a potential target for EOMA therapeutics. PMID:26961872

  12. Does Flavanol Intake Influence Mortality from Nitric Oxide-Dependent Processes? Ischemic Heart Disease, Stroke, Diabetes Mellitus, and Cancer in Panama

    Directory of Open Access Journals (Sweden)

    Vicente Bayard, Fermina Chamorro, Jorge Motta, Norman K. Hollenberg

    2007-01-01

    Full Text Available Substantial data suggest that flavonoid-rich food could help prevent cardiovascular disease and cancer. Cocoa is the richest source of flavonoids, but current processing reduces the content substantially. The Kuna living in the San Blas drink a flavanol-rich cocoa as their main beverage, contributing more than 900 mg/day and thus probably have the most flavonoid-rich diet of any population. We used diagnosis on death certificates to compare cause-specific death rates from year 2000 to 2004 in mainland and the San Blas islands where only Kuna live. Our hypothesis was that if the high flavanoid intake and consequent nitric oxide system activation were important the result would be a reduction in the frequency of ischemic heart disease, stroke, diabetes mellitus, and cancer – all nitric oxide sensitive processes. There were 77,375 deaths in mainland Panama and 558 deaths in the San Blas. In mainland Panama, as anticipated, cardiovascular disease was the leading cause of death (83.4 ± 0.70 age adjusted deaths/100,000 and cancer was second (68.4 ± 1.6. In contrast, the rate of CVD and cancer among island-dwelling Kuna was much lower (9.2 ± 3.1 and (4.4 ± 4.4 respectively. Similarly deaths due to diabetes mellitus were much more common in the mainland (24.1 ± 0.74 than in the San Blas (6.6 ± 1.94. This comparatively lower risk among Kuna in the San Blas from the most common causes of morbidity and mortality in much of the world, possibly reflects a very high flavanol intake and sustained nitric oxide synthesis activation. However, there are many risk factors and an observational study cannot provide definitive evidence.

  13. Physical Properties and Selective CO Oxidation of Coprecipitated CuO/CeO2 Catalysts Depending on the CuO in the Samples

    OpenAIRE

    Akkarat Wongkaew; Wichai Kongsi; Pichet Limsuwan

    2013-01-01

    This paper investigates the effects of CuO contents in the CuO-CeO2 catalysts to the variation in physical properties of CuO/CeO2 catalysts and correlates them to their catalytic activities on selective CO oxidation. The characteristic of crystallites were revealed by X-ray diffraction, and their morphological developments were examined with TEM, SEM, and BET methods. Catalytic performance of catalysts was investigated in the temperature range of 90–240°C. The results showed that the catalyst...

  14. Acute Ethanol Pretreatment Increases FAS-Mediated Liver Injury in Mice: Role of Oxidative Stress and CYP2E1-Dependent and Independent Pathways

    OpenAIRE

    Wang, Xiaodong; Cederbaum, Arthur I.

    2006-01-01

    This study evaluated whether acute ethanol pretreatment potentiates Fas-mediated liver injury and if oxidative stress and CYP2E1 play a role in any enhanced hepatotoxicity. There were 3-fold increases of transaminases and more extensive apoptotic necrosis of hepatocytes, and focal hemorrhages of the hepatic lobule in mice treated with Jo2 plus ethanol compared to saline control or to mice treated with Jo2 or ethanol alone. CYP2E1 catalytic activity and protein were increased 2-fold by the acu...

  15. Temperature dependence of long-term cadmium toxicity in the zebrafish is not explained by liver oxidative stress: Evidence from transcript expression to physiology

    International Nuclear Information System (INIS)

    Standard ecotoxicity tests are performed at species’ specific standard temperatures, but temperature is known to affect chemical toxicity. A temperature increase has been shown to increase cadmium toxicity in several aquatic species but information in fish is scarce. Based on literature we hypothesize that with increasing temperature, cadmium accumulation and oxidative stress increase, resulting in increased toxicity. In this study zebrafish acclimated to 12, 18, 26 (standard temperature) or 34 °C for one month, were exposed to 5 μM cadmium for 4 or 28 days at the respective acclimation temperature. Cadmium toxicity (mortality) increased with increasing temperature. PCA showed that the high mortality at 34 °C was closely correlated to an increasing tissue cadmium accumulation with increasing temperature, but not to liver oxidative damage under the form of protein carbonyl content or lipid peroxidation (measured as malondialdehyde levels) or liver antioxidative potential. Instead, acclimation to 12 °C induced the highest oxidative damage to liver proteins and lipids, and transcript levels of glucose-6P-dehydrogenase, 6P-gluconate-dehydrogenase and glutathione peroxidase were particularly good markers of cold-induced oxidative stress. At this low temperature there was no interaction with cadmium exposure and there was no sign of cadmium sensitivity. Contrastingly, the combined effect of high temperature and cadmium exposure on mortality proved synergistic. Therefore we conclude that interactions between temperature and cadmium toxicity increased with increasing temperature and that this probably played part in increasing cadmium sensitivity. Increased cadmium compartmentalization and protein carbonyl content in liver of zebrafish acclimated to the standard temperature of 26 °C probably played part in increased sensitivity towards the same cadmium body burden compared to lower temperatures. On the one hand we recognize and this study even confirms the

  16. Understanding the hydrogen and oxygen gas pressure dependence of the tribological properties of silicon oxide-doped hydrogenated amorphous carbon coatings

    OpenAIRE

    Koshigan, KD; Mangolini, F; McClimon, JB; Vacher, B.; Bec, S; Carpick, RW; Fontaine, J

    2015-01-01

    Silicon oxide-doped hydrogenated amorphous carbons (a–C:H:Si:O) are amorphous thin films used as solid lubricants in a range of commercial applications, thanks to its increased stability in extreme environments, relative to amorphous hydrogenated carbons (a–C:H). This work aims to develop a fundamental understanding of the environmental impact on the tribology of a–C:H:Si:O. Upon sliding an a–C:H:Si:O film against a steel counterbody, two friction regimes develop: high friction in high vacuum...

  17. Time-dependent effects of training on cardiovascular control in spontaneously hypertensive rats: role for brain oxidative stress and inflammation and baroreflex sensitivity.

    Directory of Open Access Journals (Sweden)

    Gustavo S Masson

    Full Text Available Baroreflex dysfunction, oxidative stress and inflammation, important hallmarks of hypertension, are attenuated by exercise training. In this study, we investigated the relationships and time-course changes of cardiovascular parameters, pro-inflammatory cytokines and pro-oxidant profiles within the hypothalamic paraventricular nucleus of the spontaneously hypertensive rats (SHR. Basal values and variability of arterial pressure and heart rate and baroreflex sensitivity were measured in trained (T, low-intensity treadmill training and sedentary (S SHR at weeks 0, 1, 2, 4 and 8. Paraventricular nucleus was used to determine reactive oxygen species (dihydroethidium oxidation products, HPLC, NADPH oxidase subunits and pro-inflammatory cytokines expression (Real time PCR, p38 MAPK and ERK1/2 expression (Western blotting, NF-κB content (electrophoretic mobility shift assay and cytokines immunofluorescence. SHR-S vs. WKY-S (Wistar Kyoto rats as time control showed increased mean arterial pressure (172±3 mmHg, pressure variability and heart rate (358±7 b/min, decreased baroreflex sensitivity and heart rate variability, increased p47phox and reactive oxygen species production, elevated NF-κB activity and increased TNF-α and IL-6 expression within the paraventricular nucleus of hypothalamus. Two weeks of training reversed all hypothalamic changes, reduced ERK1/2 phosphorylation and normalized baroreflex sensitivity (4.04±0.31 vs. 2.31±0.19 b/min/mmHg in SHR-S. These responses were followed by increased vagal component of heart rate variability (1.9-fold and resting bradycardia (-13% at the 4th week, and, by reduced vasomotor component of pressure variability (-28% and decreased mean arterial pressure (-7% only at the 8th week of training. Our findings indicate that independent of the high pressure levels in SHR, training promptly restores baroreflex function by disrupting the positive feedback between high oxidative stress and increased pro

  18. Universal Stress Protein exhibits a redox-dependent chaperone function in Arabidopsis and enhances plant tolerance to heat shock and oxidative stress

    Directory of Open Access Journals (Sweden)

    Jung eYoung Jun

    2015-12-01

    Full Text Available Although a wide range of physiological information on Universal Stress Proteins (USPs is available from many organisms, their biochemical and molecular functions remain unidentified. The biochemical function of AtUSP (At3g53990 from Arabidopsis thaliana was therefore investigated. Plants over-expressing AtUSP showed a strong resistance to heat shock and oxidative stress, compared with wild-type and Atusp knock-out plants, confirming the crucial role of AtUSP in stress tolerance. AtUSP was present in a variety of structures including monomers, dimers, trimers, and oligomeric complexes, and switched in response to external stresses from low molecular weight (LMW species to high molecular weight (HMW complexes. AtUSP exhibited a strong chaperone function under stress conditions in particular, and this activity was significantly increased by heat treatment. Chaperone activity of AtUSP was critically regulated by the redox status of cells and accompanied by structural changes to the protein. Over-expression of AtUSP conferred a strong tolerance to heat shock and oxidative stress upon Arabidopsis, primarily via its chaperone function.

  19. A Zebrafish Drug-Repurposing Screen Reveals sGC-Dependent and sGC-Independent Pro-Inflammatory Activities of Nitric Oxide.

    Directory of Open Access Journals (Sweden)

    Christine Wittmann

    Full Text Available Tissue injury and infection trigger innate immune responses. However, dysregulation may result in chronic inflammation and is commonly treated with corticosteroids and non-steroidal anti-inflammatory drugs. Unfortunately, long-term administration of both therapeutic classes can cause unwanted side effects. To identify alternative immune-modulatory compounds we have previously established a novel screening method using zebrafish larvae. Using this method we here present results of an in vivo high-content drug-repurposing screen, identifying 63 potent anti-inflammatory drugs that are in clinical use for other indications. Our approach reveals a novel pro-inflammatory role of nitric oxide. Nitric oxide affects leukocyte recruitment upon peripheral sensory nervous system or epithelial injury in zebrafish larvae both via soluble guanylate cyclase and in a soluble guanylate cyclase -independent manner through protein S-nitrosylation. Together, we show that our screening method can help to identify novel immune-modulatory activities and provide new mechanistic insights into the regulation of inflammatory processes.

  20. Muscle fibre-type dependence of neuronal nitric oxide synthase-mediated vascular control in the rat during high speed treadmill running.

    Science.gov (United States)

    Copp, Steven W; Holdsworth, Clark T; Ferguson, Scott K; Hirai, Daniel M; Poole, David C; Musch, Timothy I

    2013-06-01

    We have recently shown that nitric oxide (NO) derived from neuronal NO synthase (nNOS) does not contribute to the hyperaemic response within rat hindlimb skeletal muscle during low-speed treadmill running. This may be attributed to low exercise intensities recruiting primarily oxidative muscle and that vascular effects of nNOS-derived NO are manifest principally within glycolytic muscle. We tested the hypothesis that selective nNOS inhibition via S-methyl-l-thiocitrulline (SMTC) would reduce rat hindlimb skeletal muscle blood flow and vascular conductance (VC) during high-speed treadmill running above critical speed (asymptote of the hyperbolic speed versus time-to-exhaustion relationship for high-speed running and an important glycolytic fast-twitch fibre recruitment boundary in the rat) principally within glycolytic fast-twitch muscle. Six rats performed three high-speed treadmill runs to exhaustion to determine critical speed. Subsequently, hindlimb skeletal muscle blood flow (radiolabelled microspheres) and VC (blood flow/mean arterial pressure) were determined during supra-critical speed treadmill running (critical speed + 15%, 52.5 ± 1.3 m min(-1)) before (control) and after selective nNOS inhibition with 0.56 mg kg(-1) SMTC. SMTC reduced total hindlimb skeletal muscle blood flow (control: 241 ± 23, SMTC: 204 ± 13 ml min(-1) (100 g)(-1), P exercise by identifying fibre-type-selective peripheral vascular effects of nNOS-derived NO during high-speed treadmill running. PMID:23507879

  1. Gold nanoparticles and/or N-acetylcysteine mediate carrageenan-induced inflammation and oxidative stress in a concentration-dependent manner.

    Science.gov (United States)

    Paula, Marcos M S; Petronilho, Fabricia; Vuolo, Francieli; Ferreira, Gabriela K; De Costa, Leandro; Santos, Giulia P; Effting, Pauline S; Dal-Pizzol, Felipe; Dal-Bó, Alexandre G; Frizon, Tiago E; Silveira, Paulo C L; Pinho, Ricardo A

    2015-10-01

    We report the effect of gold nanoparticles (AuNP) in an acute inflammation model induced by carrageenan (CG) and compared this effect with those induced by the antioxidant N-acetylcysteine (NAC) alone and by the synergistic effect of NAC and AuNP together. Male Wistar rats received saline or saline containing CG administered into the pleural cavity, and some rats also received NAC (20 mg/kg) subcutaneously and/or AuNP administered into the pleural cavity immediately after surgery. Four hours later, the rats were sacrificed and pleural exudates obtained for evaluation of cytokine levels and myeloperoxidase activities. Oxidative stress parameters were also evaluated in the lungs. The results demonstrated that the inflammatory process caused by the administration of CG into the pleural cavity resulted in a substantial increase in the levels of tumor necrosis factor-α, interleukin-1β, and myeloperoxidase and a reduction in interleukin-10 levels. These levels seem to be reversed after different treatments in animals. Antioxidant enzymes exhibited positive responses after treatment of NAC + AuNP, and all treatments were effective at reducing lipid peroxidation and oxidation of thiol groups induced by CG. These findings suggest that small compounds, such as NAC plus AuNP, may be useful in the treatment of conditions associated with local inflammation. PMID:25917538

  2. Reversal magnetization dependence with the Cr and Fe oxidation states in YFe1-xCrxO3 (0≤x≤1) perovskites

    Science.gov (United States)

    Fabian, F. A.; Pedra, P. P.; Moura, K. O.; Duque, J. G. S.; Meneses, C. T.

    2016-06-01

    In this work, we have carried out a detailed study of the magnetic and structural properties of YFe1-xCrxO3 (0≤x≤1) samples with orthorhombic structure obtained by co-precipitation method. Analysis of X-ray diffraction data using Rietveld refinement show that all samples present an orthorhombic crystal system with space group Pnma. Besides, we have observed a reduction of unit cell volume with increasing of the Cr concentration. SEM images show the formation of grains of micrometer order. X-ray Absorption near edge spectroscopy (XANES) measurements show a shift of absorption edge which can be indicate there is (i) different oxidation states to Fe and Cr ions and/or (ii) a changing in the point symmetry of Fe and Cr ions to the compounds. The magnetization measurements indicate a continuous decreasing of the magnetic transition temperature as function of chromium doping. The reversal magnetization effect was observed to concentrations around x=0.5. Besides, the deviation of the Curie-Weiss law and a weak ferromagnetic behavior observed at room temperature in the M vs H curves can be attributed to the strong magnetic interactions between the transition metals with different oxidation states.

  3. Investigating the structural changes of uranium dioxide dependent on additives, Phase I - Uranium-oxide system from structural-phase aspect

    International Nuclear Information System (INIS)

    Having in mind the complex structure of the system uranium-oxygen, and that experimental studies of this system lead to controversial conclusions, an extensive review and analysis of the papers published on this subject were needed. This review wold be very useful for interpreting the expected structural changes of the uranium dioxide dependent on the additives

  4. D-saccharic acid-1,4-lactone ameliorates alloxan-induced diabetes mellitus and oxidative stress in rats through inhibiting pancreatic beta-cells from apoptosis via mitochondrial dependent pathway

    International Nuclear Information System (INIS)

    Oxidative stress plays a vital role in diabetic complications. To suppress the oxidative stress mediated damage in diabetic pathophysiology, a special focus has been given on naturally occurring antioxidants present in normal diet. D-saccharic acid 1,4-lactone (DSL), a derivative of D-glucaric acid, is present in many dietary plants and is known for its detoxifying and antioxidant properties. The aim of the present study was to evaluate the beneficial role of DSL against alloxan (ALX) induced diabetes in the pancreas tissue of Swiss albino rats. A dose-dependent study for DSL (20–120 mg/kg body weight) was carried out to find the effective dose of the compound in ALX-induced diabetic rats. ALX exposure elevated the blood glucose, glycosylated Hb, decreased the plasma insulin and disturbed the intra-cellular antioxidant machineries whereas oral administration of DSL at a dose of 80 mg/kg body weight restored these alterations close to normal. Investigating the mechanism of the protective activity of DSL we observed that it prevented the pancreatic β-cell apoptosis via mitochondria-dependent pathway. Results showed decreased mitochondrial membrane potential, enhanced cytochrome c release in the cytosol and reciprocal regulation of Bcl-2 family proteins in the diabetic rats. These events were also found to be associated with increased level of Apaf-1, caspase 9, and caspase 3 that ultimately led to pancreatic β-cell apoptosis. DSL treatment, however, counteracted these changes. In conclusion, DSL possesses the capability of ameliorating the oxidative stress in ALX-induced diabetes and thus could be a promising approach in lessening diabetic complications. Highlights: ► Oxidative stress is suggested as a key event in the pathogenesis of diabetes. ► D-saccharic acid 1,4-lactone (DSL) reduces the alloxan-induced diabetes mellitus. ► DSL normalizes cellular antioxidant machineries disturbed due to alloxan toxicity. ► DSL inhibits pancreatic β-cells apoptosis

  5. D-saccharic acid-1,4-lactone ameliorates alloxan-induced diabetes mellitus and oxidative stress in rats through inhibiting pancreatic beta-cells from apoptosis via mitochondrial dependent pathway

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Semantee [Department of Life Sciences and Biotechnology, Jadavpur University, 188, Raja S C Mullick Road, Kolkata 700 032 (India); Manna, Prasenjit [Division of Molecular Medicine, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata-700054 (India); Gachhui, Ratan [Department of Life Sciences and Biotechnology, Jadavpur University, 188, Raja S C Mullick Road, Kolkata 700 032 (India); Sil, Parames C., E-mail: parames@bosemain.boseinst.ac.in [Division of Molecular Medicine, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata-700054 (India)

    2011-12-15

    Oxidative stress plays a vital role in diabetic complications. To suppress the oxidative stress mediated damage in diabetic pathophysiology, a special focus has been given on naturally occurring antioxidants present in normal diet. D-saccharic acid 1,4-lactone (DSL), a derivative of D-glucaric acid, is present in many dietary plants and is known for its detoxifying and antioxidant properties. The aim of the present study was to evaluate the beneficial role of DSL against alloxan (ALX) induced diabetes in the pancreas tissue of Swiss albino rats. A dose-dependent study for DSL (20-120 mg/kg body weight) was carried out to find the effective dose of the compound in ALX-induced diabetic rats. ALX exposure elevated the blood glucose, glycosylated Hb, decreased the plasma insulin and disturbed the intra-cellular antioxidant machineries whereas oral administration of DSL at a dose of 80 mg/kg body weight restored these alterations close to normal. Investigating the mechanism of the protective activity of DSL we observed that it prevented the pancreatic {beta}-cell apoptosis via mitochondria-dependent pathway. Results showed decreased mitochondrial membrane potential, enhanced cytochrome c release in the cytosol and reciprocal regulation of Bcl-2 family proteins in the diabetic rats. These events were also found to be associated with increased level of Apaf-1, caspase 9, and caspase 3 that ultimately led to pancreatic {beta}-cell apoptosis. DSL treatment, however, counteracted these changes. In conclusion, DSL possesses the capability of ameliorating the oxidative stress in ALX-induced diabetes and thus could be a promising approach in lessening diabetic complications. Highlights: Black-Right-Pointing-Pointer Oxidative stress is suggested as a key event in the pathogenesis of diabetes. Black-Right-Pointing-Pointer D-saccharic acid 1,4-lactone (DSL) reduces the alloxan-induced diabetes mellitus. Black-Right-Pointing-Pointer DSL normalizes cellular antioxidant machineries

  6. Atomic Resolution Observation of a Size-Dependent Change in the Ripening Modes of Mass-Selected Au Nanoclusters Involved in CO Oxidation.

    Science.gov (United States)

    Hu, Kuo-Juei; Plant, Simon R; Ellis, Peter R; Brown, Christopher M; Bishop, Peter T; Palmer, Richard E

    2015-12-01

    Identifying the ripening modes of supported metal nanoparticles used in heterogeneous catalysis can provide important insights into the mechanisms that lead to sintering. We report the observation of a crossover from Smoluchowski to Ostwald ripening, under realistic reaction conditions, for monomodal populations of precisely defined gold particles in the nanometer size range, as a function of decreasing particle size. We study the effects of the CO oxidation reaction on the size distributions and atomic structures of mass-selected Au(561±13), Au(923±20) and Au(2057±45) clusters supported on amorphous carbon films. Under the same conditions, Au(561±13) and Au(923±20) clusters are found to exhibit Ostwald ripening, whereas Au(2057±45) ripens through cluster diffusion and coalescence only (Smoluchowski ripening). The Ostwald ripening is not activated by thermal annealing or heating in O2 alone. PMID:26544914

  7. Characterizing temperature-dependent photo-oxidation to explain the abrupt transition from thermal to non-thermal laser damage mechanisms at 413 nm

    Science.gov (United States)

    Denton, Michael L.; Clark, C. D., III; Noojin, Gary D.; Estlack, Larry E.; Schenk, Adam C.; Burney, Curtis W.; Rockwell, Benjamin A.; Thomas, Robert J.

    2011-03-01

    Laser exposure duration dictates whether tissues subjected to short visible wavelengths ( = 100 s) mechanisms. Somewhere between these extremes, an abrupt transition between the two damage mechanisms has been found for both in vitro and animal retinal models (J. Biomed. Opt. 15, 030512, 2010). Non-thermal (photochemical) damage is characterized by an inverse relationship between damage threshold irradiance and exposure duration (irradiance reciprocity). We have found that exposures of 40 - 60 s in an in vitro retinal model require radiant exposures well above the expected requirement for nonthermal damage, introducing the concept that damage was forced to be thermal in mechanism. Here we quantify and compare photo-oxidative processes at ambient temperatures between 35 - 50 °C.

  8. Defect-dependent carrier transport behavior of polymer:ZnO composites/electrodeposited CdS/indium tin oxide devices

    International Nuclear Information System (INIS)

    Currents through the poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) and ZnO nanoparticles (PEDOT:PSS:ZnO)/CdS/indium tin oxide (ITO) hetero-structures are studied. The authors introduced the electrodeposition technique with sulfide treatment to improve the film quality of CdS. It is shown that sulfide treatment leads to a reduction in the number of donor-like defects (that is, sulfur vacancies and cadmium interstitials) in the CdS films, which leads to the conversion of carrier transport behavior from Poole-Frenkel emission to thermionic emission-diffusion for PEDOT:PSS:ZnO/CdS/ITO devices. A correlation is identified for providing a guide to control the current transport behavior of PEDOT:PSS:ZnO/CdS/ITO devices

  9. Defect-dependent carrier transport behavior of polymer:ZnO composites/electrodeposited CdS/indium tin oxide devices

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yow-Jon, E-mail: rzr2390@yahoo.com.tw; You, C. F. [Institute of Photonics, National Changhua University of Education, Changhua 500, Taiwan (China)

    2015-07-28

    Currents through the poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) and ZnO nanoparticles (PEDOT:PSS:ZnO)/CdS/indium tin oxide (ITO) hetero-structures are studied. The authors introduced the electrodeposition technique with sulfide treatment to improve the film quality of CdS. It is shown that sulfide treatment leads to a reduction in the number of donor-like defects (that is, sulfur vacancies and cadmium interstitials) in the CdS films, which leads to the conversion of carrier transport behavior from Poole-Frenkel emission to thermionic emission-diffusion for PEDOT:PSS:ZnO/CdS/ITO devices. A correlation is identified for providing a guide to control the current transport behavior of PEDOT:PSS:ZnO/CdS/ITO devices.

  10. An ultra-high performance liquid chromatography-tandem mass spectrometric assay for quantifying 3-ketocholanoic acid: Application to the human liver microsomal CYP3A-dependent lithocholic acid 3-oxidation assay.

    Science.gov (United States)

    Bansal, Sumit; Chai, Swee Fen; Lau, Aik Jiang

    2016-06-15

    Lithocholic acid (LCA), a hepatotoxic and carcinogenic bile acid, is metabolized to 3-ketocholanoic acid (3-KCA) by cytochrome P450 3A (CYP3A). In the present study, the objectives were to develop and validate an ultra-high performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method to quantify 3-KCA and apply it to the human liver microsomal CYP3A-dependent LCA 3-oxidation assay. Chromatographic separation was achieved on a Waters ACQUITY™ UPLC C18 column (50×2.1mm, 1.7μm) with a gradient system consisting of 0.1% v/v formic acid in water (solvent A) and 0.1% v/v formic acid in acetonitrile (solvent B). The retention time was 3.73min for 3-KCA and 2.73min for cortisol (internal standard). Positive electrospray ionization with multiple reaction monitoring (MRM) mode was used to quantify 3-KCA (m/z 375.4→135.2) and cortisol (m/z 363.5→121.0). The limit of detection of 3-KCA was 10μM, the lower limit of quantification was 33.3μM, and the calibration curve was linear from 0.05-10μM with r(2)>0.99. Intra-day and inter-day accuracy and precision were LCA 3-oxidation assay was linear with respect to the amount of microsomal protein (up to 40μg) and incubation time (5-30min). Enzyme kinetics experiment indicated that LCA 3-oxidation followed the Michaelis-Menten model with an apparent Km of 26±7μM and Vmax of 303±50pmol/min/mg protein. This novel UPLC-MS/MS method for quantifying 3-KCA offers a specific, sensitive, and fast approach to determine liver microsomal LCA 3-oxidation. PMID:27153105

  11. Ultraviolet-induced vanadate-dependent modification and cleavage of skeletal myosin subfragment 1 heavy chain. 2. Oxidation of serine in the 23-kDa NH2-terminal tryptic peptide

    International Nuclear Information System (INIS)

    Myosin subfragment 1 (S1) can be specifically photomodified at the active site without polypeptide chain cleavage by irradiating the stable MgADP-orthovanadate-S1 complex with UV light above 300 nm. Here, the UV spectral properties of photomodified S1 were used to determined the nature and location of the photomodified residue(s) within S1. By comparison of the unusual pH dependence of the UV absorption spectrum of the photomodified S1 to that of the S1-MgADP-V/sub i/ complex as a control the photomodified residue(s) was (were) localized to the 23-kDa NH2-terminal tryptic peptide of the heavy chain. NaBH4 reduced the photomodified S1, but not the control, to regenerate the original spectral properties and ATPase activities of the unmodified S1. Amino acid analysis of photomodified S1 reduced with NaB3H4 gave only [3H]serine, suggesting the hydroxyl group of serine had been oxidized to a serine aldehyde. The pH dependence of the absorption spectrum of the photomodified enzyme can be explained by an equilibrium between a chromophoric enolate anion of the serine aldehyde (favored in base) and less chromophoric keto and enol forms (favored in acid). The oxidized serine(s) was (were) shown to be directly involved with the vanadate-dependent photocleavage of the S1 heavy chain previously described by Grammer et al. (1988). This serine(s) is (are) likely to be important to the binding and hydrolysis of the γ-PO4 of ATP at the active site of S1

  12. Oxidative Stress in Neurodegeneration

    Directory of Open Access Journals (Sweden)

    Varsha Shukla

    2011-01-01

    Full Text Available It has been demonstrated that oxidative stress has a ubiquitous role in neurodegenerative diseases. Major source of oxidative stress due to reactive oxygen species (ROS is related to mitochondria as an endogenous source. Although there is ample evidence from tissues of patients with neurodegenerative disorders of morphological, biochemical, and molecular abnormalities in mitochondria, it is still not very clear whether the oxidative stress itself contributes to the onset of neurodegeneration or it is part of the neurodegenerative process as secondary manifestation. This paper begins with an overview of how oxidative stress occurs, discussing various oxidants and antioxidants, and role of oxidative stress in diseases in general. It highlights the role of oxidative stress in neurodegenerative diseases like Alzheimer's, Parkinson's, and Huntington's diseases and amyotrophic lateral sclerosis. The last part of the paper describes the role of oxidative stress causing deregulation of cyclin-dependent kinase 5 (Cdk5 hyperactivity associated with neurodegeneration.

  13. Size-dependent modulation of graphene oxide-aptamer interactions for an amplified fluorescence-based detection of aflatoxin B1 with a tunable dynamic range.

    Science.gov (United States)

    Zhang, JingJing; Li, Zengmei; Zhao, Shancang; Lu, Yi

    2016-06-20

    Aflatoxin B1 (AFB1) is a common toxin found in many foods. While AFB1 sensors have been reported, few studies have shown amplified detection with tunable dynamic ranges. We herein report a simple and highly sensitive amplified aptamer-based fluorescent sensor for AFB1, which relies on the ability of nano-graphene oxide (GO) to protect aptamers from nuclease cleavage for amplified detection and on the nanometer size effect of GO to tune the dynamic range and sensitivity. The assay was performed by simply mixing the carboxyl-X-rhodamine (ROX)-labeled AFB1 aptamer, the GO, the nuclease, and the AFB1 samples. Modulating the size of the GO nanosheet resulted in three dynamic ranges, i.e., 12.5 to 312.5 ng mL(-1), 1.0 to 100 ng mL(-1), and 5.0 to 50 ng mL(-1), with corresponding limits of detection of 10.0 ng mL(-1), 0.35 ng mL(-1) and 15.0 ng mL(-1), respectively. The sensor was highly selective against other aflatoxins and common molecules in foods, and its performance was verified in corn samples spiked with known concentration of AFB1. PMID:27137348

  14. Oral treatment with the herbal formula B401 protects against aging-dependent neurodegeneration by attenuating oxidative stress and apoptosis in the brain of R6/2 mice

    Directory of Open Access Journals (Sweden)

    Wang SE

    2015-11-01

    Full Text Available Sheue-Er Wang,1,2 Ching-Lung Lin,1 Chih-Hsiang Hsu,1 Shuenn-Jyi Sheu,3 Chung-Hsin Wu1 1Department of Life Science, National Taiwan Normal University, Taipei, 2Department of Pathological Inspection, Saint Paul’s Hospital, Taoyuan, 3Brion Research Institute of Taiwan, Taipei, Taiwan Background: Neurodegeneration is characterized by progressive neurological deficits due to selective neuronal loss in the nervous system. Huntington’s disease (HD is an incurable neurodegenerative disorder. Neurodegeneration in HD patients shows aging-dependent pattern. Our previous study has suggested that a herbal formula B401 may have neuroprotective effects in the brains of R6/2 mice. Objective: To clarify possible mechanisms for neurodegeneration, which improves the understanding the aging process. This study focuses on clarifying neurodegenerative mechanisms and searching potential therapeutic targets in HD patients. Methods: The oxidative stress and apoptosis were compared in the brain tissue between R6/2 HD mice with and without oral B401 treatment. Expressions of proteins for oxidative stress and apoptosis in the brain tissue of R6/2 HD mice were examined by using immunostaining and Western blotting techniques. Results: R6/2 HD mice with oral B401 treatment significantly reduced reactive oxygen species levels in the blood, but markedly increased expressions of superoxide dismutase 2 in the brain tissue. Furthermore, R6/2 HD mice with oral B401 treatment significantly increased expressions of B-cell lymphoma 2 (Bcl-2, but significantly reduced expressions of Bcl-2-associated X protein (Bax, calpain, and caspase-3 in the brain tissue. Conclusion: Our findings provide evidence that the herbal formula B401 can remedy for aging-dependent neurodegeneration of R6/2 mice via suppressing oxidative stress and apoptosis in the brain. We suggest that the herbal formula B401 can be developed as a potential health supplement for ameliorating aging-dependent

  15. Temperature-dependent toxicities of nano zinc oxide to marine diatom, amphipod and fish in relation to its aggregation size and ion dissolution.

    Science.gov (United States)

    Wong, Stella W Y; Leung, Kenneth M Y

    2014-08-01

    This study, for the first time, concurrently investigated the influence of seawater temperature, exposure concentration and time on the aggregation size and ion dissolution of nano zinc oxides (nZnO) in seawater, and the interacting effect of temperature and waterborne exposure of nZnO to the marine diatom Skeletonema costatum, amphipod Melita longidactyla and fish Oryzias melastigma, respectively. Our results showed that aggregate size was jointly affected by seawater temperature, nZnO concentration and exposure time. Among the three factors, the concentration of nZnO was the most important and followed by exposure time, whereas temperature was less important as reflected by their F values in the three-way analysis of variance (concentration: F3, 300 = 247.305; time: F2, 300 = 20.923 and temperature: F4, 300 = 4.107; All p values <0.001). The aggregate size generally increased with increasing nZnO concentration and exposure time. The release of Zn ions from nZnO was significantly influenced by seawater temperature and exposure time; the ion dissolution rate generally increased with decreasing temperature and increasing exposure time. Growth inhibition of diatoms increased with increasing temperature, while temperature and nZnO had an interactional effect on their photosynthesis. For the amphipod, mortality was positively correlated with temperature. Fish larvae growth rate was only affected by temperature but not nZnO, while the two factors interactively modulated the expression of heat shock and metallothionein proteins. Evidently, temperature can influence aggregate size and ion dissolution and thus toxicity of nZnO to the marine organisms in a species-specific manner. PMID:24219175

  16. Humic Substances-dependent Aggregation and Transport of Cerium Oxide Nanoparticles in Porous Media at Different pHs and Ionic Strengths

    Science.gov (United States)

    Mu, L.; Jacobson, A. R.; Darnault, C. J. G.

    2015-12-01

    Cerium oxide nanoparticles (CeO2 NPs) are commonly used in several fields and industries, such as chemical and pharmaceutical, due to both their physical and chemical properties. For example, they are employed in the manufacturing of catalysts, as fuel additives, and as polishing agents. The release and exposure to CeO2 NPs can occur during their fabrication, application, and waste disposal, as well as through their life-cycle and accidents. Therefore, the assessment of the dynamic nature of CeO2 NPs stability and mobilty in the environment is of paramount importance to establish the environmental and public health risks associated with their inevitable release in the environment. Humic substances are a key element of soils and have been revealed to possibly affect the fate and transport of nanoparticles in soils. Consequently, our present research aims at investigating the influence that different pHs, monovalent and divalent cations, Suwannee River humic acid, and Suwanee River fulvic acid have on the aggregation, transport, and deposition of CeO2 NPs. Batch studies performed with different concentrations of humic and fulvic acids associated with a wide spectrum of pHs and ionic strengths were examined. Key variables from these batch studies were then examined to simulate experimental conditions commonly encountered in the soil-water system to conduct column transport experiments in order to establish the fate and transport of CeO2 NPs in saturated porous media, which is a critical phase in characterizing the behavior of CeO2 NPs in subsurface environmental systems.

  17. Composition-dependent morphostructural properties of Ni-Cu oxide nanoparticles confined within the channels of ordered mesoporous SBA-15 silica.

    Science.gov (United States)

    Ungureanu, Adrian; Dragoi, Brindusa; Chirieac, Alexandru; Ciotonea, Carmen; Royer, Sébastien; Duprez, Daniel; Mamede, Anne Sophie; Dumitriu, Emil

    2013-04-24

    NiO and NiO-CuO polycrystalline rodlike nanoparticles were confined and stabilized within the channels of ordered mesoporous SBA-15 silica by a simple and viable approach consisting in incipient wetness impregnation of the calcined support with aqueous solutions of metal nitrates followed by a mild drying step at 25 °C and calcination. As revealed by low- and high-angle XRD, N2 adsorption/desorption, HRTEM/EDXS and H2 TPR analyses, the morphostructural properties of NiO-CuO nanoparticles can be controlled by adjusting their chemical composition, creating the prerequisites to obtain high performance bimetallic catalysts. Experimental evidence by in situ XRD monitoring during the thermoprogrammed reduction indicates that the confined NiO-CuO nanoparticles evolve into thermostable and well-dispersed Ni-Cu heterostructures. The strong Cu-Ni and Ni-support interactions demonstrated by TPR and XPS were put forward to explain the formation of these new bimetallic structures. The optimal Ni-Cu/SBA-15 catalyst (i.e., Cu/(Cu+Ni) atomic ratio of 0.2) proved a greatly enhanced reducibility and H2 chemisorption capacity, and an improved activity in the hydrogenation of cinnamaldehyde, as compared with the monometallic Ni/SBA-15 or Cu/SBA-15 counterparts, which can be associated with the synergism between nickel and copper and high dispersion of active components on the SBA-15 host. The unique structure and controllable properties of both oxidic and metallic forms of Ni-Cu/SBA-15 materials make them very attractive for both fundamental research and practical catalytic applications. PMID:23496429

  18. Properties of immature myeloid progenitors with nitric-oxide-dependent immunosuppressive activity isolated from bone marrow of tumor-free mice.

    Directory of Open Access Journals (Sweden)

    Parvin Forghani

    Full Text Available Myeloid derived suppressor cells (MDSCs from tumor-bearing mice are important negative regulators of anti-cancer immune responses, but the role for immature myeloid cells (IMCs in non-tumor-bearing mice in the regulation of immune responses are poorly described. We studied the immune-suppressive activity of IMCs from the bone marrow (BM of C57Bl/6 mice and the mechanism(s by which they inhibit T-cell activation and proliferation. IMCs, isolated from BM by high-speed FACS, inhibited mitogen-induced proliferation of CD4(+ and CD8(+ T-cells in vitro. Cell-to-cell contact of T-cells with viable IMCs was required for suppression. Neither neutralizing antibodies to TGFβ1, nor genetic disruption of indolamine 2,3-dioxygenase, abrogated IMC-mediated suppressive activity. In contrast, suppression of T-cell proliferation was absent in cultures containing IMCs from interferon-γ (IFN-γ receptor KO mice or T-cells from IFN-γ KO mice (on the C57Bl/6 background. The addition of NO inhibitors to co-cultures of T-cells and IMC significantly reduced the suppressive activity of IMCs. IFN-γ signaling between T-cells and IMCs induced paracrine Nitric Oxide (NO release in culture, and the degree of inhibition of T-cell proliferation was proportional to NO levels. The suppressive activity of IMCs from the bone marrow of tumor-free mice was comparable with MDSCs from BALB/c bearing mice 4T1 mammary tumors. These results indicate that IMCs have a role in regulating T-cell activation and proliferation in the BM microenvironment.

  19. Quantitative Profiling of Protein S-Glutathionylation Reveals Redox-Dependent Regulation of Macrophage Function during Nanoparticle-Induced Oxidative Stress.

    Science.gov (United States)

    Duan, Jicheng; Kodali, Vamsi K; Gaffrey, Matthew J; Guo, Jia; Chu, Rosalie K; Camp, David G; Smith, Richard D; Thrall, Brian D; Qian, Wei-Jun

    2016-01-26

    Engineered nanoparticles (ENPs) are increasingly utilized for commercial and medical applications; thus, understanding their potential adverse effects is an important societal issue. Herein, we investigated protein S-glutathionylation (SSG) as an underlying regulatory mechanism by which ENPs may alter macrophage innate immune functions, using a quantitative redox proteomics approach for site-specific measurement of SSG modifications. Three high-volume production ENPs (SiO2, Fe3O4, and CoO) were selected as representatives which induce low, moderate, and high propensity, respectively, to stimulate cellular reactive oxygen species (ROS) and disrupt macrophage function. The SSG modifications identified highlighted a broad set of redox sensitive proteins and specific Cys residues which correlated well with the overall level of cellular redox stress and impairment of macrophage phagocytic function (CoO > Fe3O4 ≫ SiO2). Moreover, our data revealed pathway-specific differences in susceptibility to SSG between ENPs which induce moderate versus high levels of ROS. Pathways regulating protein translation and protein stability indicative of ER stress responses and proteins involved in phagocytosis were among the most sensitive to SSG in response to ENPs that induce subcytoxic levels of redox stress. At higher levels of redox stress, the pattern of SSG modifications displayed reduced specificity and a broader set pathways involving classical stress responses and mitochondrial energetics (e.g., glycolysis) associated with apoptotic mechanisms. An important role for SSG in regulation of macrophage innate immune function was also confirmed by RNA silencing of glutaredoxin, a major enzyme which reverses SSG modifications. Our results provide unique insights into the protein signatures and pathways that serve as ROS sensors and may facilitate cellular adaption to ENPs, versus intracellular targets of ENP-induced oxidative stress that are linked to irreversible cell outcomes. PMID

  20. Aluminum oxide from trimethylaluminum and water by atomic layer deposition: The temperature dependence of residual stress, elastic modulus, hardness and adhesion

    International Nuclear Information System (INIS)

    Use of atomic layer deposition (ALD) in microelectromechanical systems (MEMS) has increased as ALD enables conformal growth on 3-dimensional structures at relatively low temperatures. For MEMS device design and fabrication, the understanding of stress and mechanical properties such as elastic modulus, hardness and adhesion of thin film is crucial. In this work a comprehensive characterization of the stress, elastic modulus, hardness and adhesion of ALD aluminum oxide (Al2O3) films grown at 110–300 °C from trimethylaluminum and water is presented. Film stress was analyzed by wafer curvature measurements, elastic modulus by nanoindentation and surface-acoustic wave measurements, hardness by nanoindentation and adhesion by microscratch test and scanning nanowear. The films were also analyzed by ellipsometry, optical reflectometry, X-ray reflectivity and time-of-flight elastic recoil detection for refractive index, thickness, density and impurities. The ALD Al2O3 films were under tensile stress in the scale of hundreds of MPa. The magnitude of the stress decreased strongly with increasing ALD temperature. The stress was stable during storage in air. Elastic modulus and hardness of ALD Al2O3 saturated to a fairly constant value for growth at 150 to 300 °C, while ALD at 110 °C gave softer films with lower modulus. ALD Al2O3 films adhered strongly on cleaned silicon with SiOx termination. - Highlights: • The residual stress of Al2O3 was tensile and stable during the storage in air. • Elastic modulus of Al2O3 saturated to at 170 GPa for films grown at 150 to 300 °C. • At 110 °C Al2O3 films were softer with high residual hydrogen and lower density. • The Al2O3 adhered strongly on the SiOx-terminated silicon

  1. The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide-mediated vasorelaxation in BALB/c mice.

    Science.gov (United States)

    Gohin, S; Carriero, A; Chenu, C; Pitsillides, A A; Arnett, T R; Marenzana, M

    2016-03-01

    There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L-NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1-34] (80 µg/kg/day) or L-NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro-CT, histomorphometry and three-point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P flow, whereas L-NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co-treatment with L-NAME restricted the PTH-stimulated increase in cortical bone formation but had no clear-cut effects in trabecular bone. Co-treatment with L-NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO-mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26834008

  2. Identification of novel oxidized protein substrates and physiological partners of the mitochondrial ATP-dependent Lon-like protease Pim1

    DEFF Research Database (Denmark)

    Bayot, Aurélien; Gareil, Monique; Rogowska-Wrzesinska, Adelina; Roepstorff, Peter; Friguet, Bertrand; Bulteau, Anne-Laure

    2010-01-01

    ATP-dependent proteases are currently emerging as key regulators of mitochondrial functions. Among these proteolytic systems, Pim1, a Lon-like serine protease in Saccharomyces cerevisiae, is involved in the control of selective protein turnover in the mitochondrial matrix. In the absence of Pim1......, yeast cells have been shown to accumulate electron-dense inclusion bodies in the matrix space, to lose integrity of mitochondrial genome, and to be respiration-deficient. Because of the severity of phenotypes associated with the depletion of Pim1, this protease appears to be an essential component of...... the protein quality control machinery in mitochondria and to exert crucial functions during the biogenesis of this organelle. Nevertheless, its physiological substrates and partners are not fully characterized. Therefore, we used the combination of different proteomic techniques to assess the nature...

  3. Characterization of temperature-dependent carrier transport in disordered indium-tin-oxide/poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polyfluorene/Ca/Al polymer structures

    International Nuclear Information System (INIS)

    The temperature-dependent electrical characteristics of polyfluorene-based polymer structures over a temperature range from 200 to 300 K are systematically investigated in this study. Initially, using the definitions of the Berthelot-type model, it is found that the sample exhibits a higher Berthelot-type temperature TB with high driving voltage, indicating that carrier transport in a disordered system manifests Berthelot-type behaviors. The ideal current density-voltage curve for the polymer structures given the carrier transmit mechanism is further elucidated by taking into account the ohmic conduction, trap charge limited current, and Mott and Gurney model of space charge limited current. The proposed procedure is simple and can be used to characterize the material with reasonable accuracy. We also study the density of the traps Ht, and the characteristic energy of the distribution Et to better understand the carrier-transport process in organic materials and structures.

  4. Recombinant human brain natriuretic peptide attenuates trauma-/haemorrhagic shock-induced acute lung injury through inhibiting oxidative stress and the NF-κB-dependent inflammatory/MMP-9 pathway.

    Science.gov (United States)

    Song, Zhi; Zhao, Xiu; Liu, Martin; Jin, Hongxu; Wang, Ling; Hou, Mingxiao; Gao, Yan

    2015-12-01

    Acute lung injury (ALI) is one of the most serious complications in traumatic patients and is an important part of multiple organ dysfunction syndrome (MODS). Recombinant human brain natriuretic peptide (rhBNP) is a peptide with a wide range of biological activity. In this study, we investigated local changes in oxidative stress and the NF-κB-dependent matrix metalloproteinase-9 (MMP-9) pathway in rats with trauma/haemorrhagic shock (TH/S)-induced ALI and evaluated the effects of pretreatment with rhBNP. Forty-eight rats were randomly divided into four groups: sham operation group, model group, low-dosage rhBNP group and high-dosage rhBNP group (n = 12 for each group). Oxidative stress and MPO activity were measured by ELISA kits. MMP-9 activity was detected by zymography analysis. NF-κB activity was determined using Western blot assay. With rhBNP pretreatment, TH/S-induced protein leakage, increased MPO activity, lipid peroxidation and metalloproteinase (MMP)-9 activity were inhibited. Activation of antioxidative enzymes was reversed. The phosphorylation of NF-κB and the degradation of its inhibitor IκB were suppressed. The results suggested that the protection mechanism of rhBNP is possibly mediated through upregulation of anti-oxidative enzymes and inhibition of NF-κB activation. More studies are needed to further evaluate whether rhBNP is a suitable candidate as an effective inhaling drug to reduce the incidence of TH/S-induced ALI. PMID:26852688

  5. PH dependence of deuterium isotope effects and tritium exchange in the bovine plasma amine oxidase reaction: a role for single-base catalysis in amine oxidation and imine exchange

    International Nuclear Information System (INIS)

    The pH dependence of steady-state parameters for [1,1-1H2]- and [1,1-2H2]benzylamine oxidation and of tritium exchange from [2-3H]dopamine has been measured in the bovine plasma amine oxidase reaction. Deuterium isotope effects on kcat/Km for benzylamine are observed to be constant, near the intrinsic value of 13.5, over the experimental pH range, indicating that C-H bond cleavage is fully rate limiting for this parameter. As a consequence, pKa values derived from kcat/Km profiles, 8.0 +/- 0.1 (pK1) and 9.0 +/- 0.16 (pKs), can be ascribed to microscopic pKa values for the ionization of an essential active site residue (EB1) and substrate, respectively. Profiles for kcat and Dkcat show that EB1 undergoes a perturbation from 8.0 to 5.6 +/- 0.3 (pK1') in the presence of substrate; additionally, a second ionization, pK2 = 7.25 +/- 0.25, is observed to mediate but not be essential for enzyme reoxidation. The pH dependence of the ratio of tritium exchange to product formation for dopamine also indicates base catalysis with a pKexch = 5.5 +/- 0.01, which is within experimental error of pK1'. We conclude that the data presented herein support a single residue catalyzing both substrate oxidation and exchange, consistent with recent stereochemical results that implicate a syn relationship between these processes [Farnum, M., and Klinman, J.P. (1985) Fed. Proc., Fed. Am. Soc. Exp. Biol. 44, 1055]. This conclusion contrasts with earlier kinetic data in support of a large rate differential for the exchange of hydrogen from C-1 vs. C-2 of phenethylamine derivatives

  6. Composition dependence of interface control and optimization on the performance of an HfTiON gate dielectric metal-oxide-semiconductor capacitor

    International Nuclear Information System (INIS)

    Composition dependence of interface control, band alignment and electrical properties of HfTiON/Si grown by sputtering has been studied by spectroscopy ellipsometry (SE), x-ray photoelectron spectroscopy (XPS) and electrical measurement. Analysis from XPS has confirmed that the interfacial layer consisting of silicate and SiOx is formed unavoidably, irrespective of composition ratio. Meanwhile, reduction in band gap and asymmetric band alignment has been detected for HfTiON films with the increase in Ti composition. To meet the requirements of high-k dielectrics with the barrier height of over 1 eV, the incorporation composition ratio needs to be carefully optimized. As a result, improved C–V characteristics and reduced leakage current have been achieved from HfTiON gate dielectric MOS capacitors with optimized composition ratio of Hf:Ti = 1:1, which can be attributed to the reduction in oxygen-related traps and the obtained near-symmetric band alignment relative to Si

  7. DRP1-dependent apoptotic mitochondrial fission occurs independently of BAX, BAK and APAF1 to amplify cell death by BID and oxidative stress.

    Science.gov (United States)

    Oettinghaus, Björn; D'Alonzo, Donato; Barbieri, Elisa; Restelli, Lisa Michelle; Savoia, Claudia; Licci, Maria; Tolnay, Markus; Frank, Stephan; Scorrano, Luca

    2016-08-01

    During apoptosis mitochondria undergo cristae remodeling and fragmentation, but how the latter relates to outer membrane permeabilization and downstream caspase activation is unclear. Here we show that the mitochondrial fission protein Dynamin Related Protein (Drp) 1 participates in cytochrome c release by selected intrinsic death stimuli. While Bax, Bak double deficient (DKO) and Apaf1(-/-) mouse embryonic fibroblasts (MEFs) were less susceptible to apoptosis by Bcl-2 family member BID, H2O2, staurosporine and thapsigargin, Drp1(-/-) MEFs were protected only from BID and H2O2. Resistance to cell death of Drp1(-/-) and DKO MEFs correlated with blunted cytochrome c release, whereas mitochondrial fragmentation occurred in all cell lines in response to all tested stimuli, indicating that other mechanisms accounted for the reduced cytochrome c release. Indeed, cristae remodeling was reduced in Drp1(-/-) cells, potentially explaining their resistance to apoptosis. Our results indicate that caspase-independent mitochondrial fission and Drp1-dependent cristae remodeling amplify apoptosis. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi. PMID:26997499

  8. Current-perpendicular-to-the-plane magnetoresistance from large interfacial spin-dependent scattering between Co50Fe50 magnetic layer and In-Zn-O conductive oxide spacer layer

    International Nuclear Information System (INIS)

    We have investigated electrically conductive indium-zinc-oxide (IZO) deposited by magnetron sputtering as spacer layer for current-perpendicular-to-the-plane giant magnetoresistance sensor devices. Spin-valves with a Co50Fe50/IZO/Co50Fe50 trilayer showed resistance-area product (RA) ranging from 110 to 250 mΩ μm2, significantly larger than all-metal structures with Ag or Cu spacers (∼40 mΩ μm2). Magnetoresistance ratios (ΔR/R) of 2.5% to 5.5% depending on the IZO spacer thickness (1.5–6.0 nm), corresponding to ΔRA values from 3 to 13 mΩ μm2, were obtained. The values of ΔRA with the IZO spacers and Co50Fe50 magnetic layers were significantly larger than those with conventional metal spacers and Co50Fe50 magnetic layers (∼1–2 mΩ μm2). The dependence of ΔRA on the magnetic layer thickness suggests that the larger ΔRA obtained with IZO spacer is due to a large interfacial spin-dependent scattering caused by the large specific resistance at the Co50Fe50/IZO interface. From structural characterization by TEM and the observed dependence of the RA dispersion on device size, the electric current flowing through the IZO spacer is thought to be laterally uniform, similar to normal metal spacers

  9. Current-perpendicular-to-the-plane magnetoresistance from large interfacial spin-dependent scattering between Co{sub 50}Fe{sub 50} magnetic layer and In-Zn-O conductive oxide spacer layer

    Energy Technology Data Exchange (ETDEWEB)

    Nakatani, T. M., E-mail: Tomoya.Nakatani@hgst.com; Childress, J. R. [San Jose Research Center, HGST, a Western Digital company, 3403 Yerba Buena Road, San Jose, California 95135 (United States)

    2015-06-28

    We have investigated electrically conductive indium-zinc-oxide (IZO) deposited by magnetron sputtering as spacer layer for current-perpendicular-to-the-plane giant magnetoresistance sensor devices. Spin-valves with a Co{sub 50}Fe{sub 50}/IZO/Co{sub 50}Fe{sub 50} trilayer showed resistance-area product (RA) ranging from 110 to 250 mΩ μm{sup 2}, significantly larger than all-metal structures with Ag or Cu spacers (∼40 mΩ μm{sup 2}). Magnetoresistance ratios (ΔR/R) of 2.5% to 5.5% depending on the IZO spacer thickness (1.5–6.0 nm), corresponding to ΔRA values from 3 to 13 mΩ μm{sup 2}, were obtained. The values of ΔRA with the IZO spacers and Co{sub 50}Fe{sub 50} magnetic layers were significantly larger than those with conventional metal spacers and Co{sub 50}Fe{sub 50} magnetic layers (∼1–2 mΩ μm{sup 2}). The dependence of ΔRA on the magnetic layer thickness suggests that the larger ΔRA obtained with IZO spacer is due to a large interfacial spin-dependent scattering caused by the large specific resistance at the Co{sub 50}Fe{sub 50}/IZO interface. From structural characterization by TEM and the observed dependence of the RA dispersion on device size, the electric current flowing through the IZO spacer is thought to be laterally uniform, similar to normal metal spacers.

  10. Oxidative stress

    Directory of Open Access Journals (Sweden)

    Stevanović Jelka

    2012-01-01

    Full Text Available The unceasing need for oxygen is in contradiction to the fact that it is in fact toxic to mammals. Namely, its monovalent reduction can have as a consequence the production of short-living, chemically very active free radicals and certain non-radical agents (nitrogen-oxide, superoxide-anion-radicals, hydroxyl radicals, peroxyl radicals, singlet oxygen, peroxynitrite, hydrogen peroxide, hypochlorous acid, and others. There is no doubt that they have numerous positive roles, but when their production is stepped up to such an extent that the organism cannot eliminate them with its antioxidants (superoxide-dismutase, glutathione-peroxidase, catalase, transferrin, ceruloplasmin, reduced glutathion, and others, a series of disorders is developed that are jointly called „oxidative stress.“ The reactive oxygen species which characterize oxidative stress are capable of attacking all main classes of biological macromolecules, actually proteins, DNA and RNA molecules, and in particular lipids. The free radicals influence lipid peroxidation in cellular membranes, oxidative damage to DNA and RNA molecules, the development of genetic mutations, fragmentation, and the altered function of various protein molecules. All of this results in the following consequences: disrupted permeability of cellular membranes, disrupted cellular signalization and ion homeostasis, reduced or loss of function of damaged proteins, and similar. That is why the free radicals that are released during oxidative stress are considered pathogenic agents of numerous diseases and ageing. The type of damage that will occur, and when it will take place, depends on the nature of the free radicals, their site of action and their source. [Projekat Ministarstva nauke Republike Srbije, br. 173034, br. 175061 i br. 31085

  11. Size-dependent catalytic performance of CuO on γ-Al2O3: NO reduction versus NH3 oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Tonkyn, Russell G.; Tran, Diana N.; Mei, Donghai; Cho, Sung June; Kovarik, Libor; Lee, Jong H.; Peden, Charles HF; Szanyi, Janos

    2012-05-25

    Catalytic reaction pathways of NH{sub 3} on CuO/{gamma}-Al{sub 2}O{sub 3} catalysts during NH{sub 3} SCR reactions were investigated under oxygen-rich conditions. On 10 wt % CuO/{gamma}-Al{sub 2}O{sub 3}, NH{sub 3} reacted with oxygen to produce NO{sub x}. In contrast, on the 0.5 wt % CuO/{gamma}-Al{sub 2}O{sub 3} catalyst NH{sub 3} reacted primarily with NO to form N{sub 2} with conversion efficiency of {approx}80% at 450 C. H{sub 2}-TPR results show that Cu species present in 10 wt % CuO/{gamma}-Al{sub 2}O{sub 3} can be easily reduced at {approx}160 C, which suggests the formation of large CuO clusters on the alumina surface. On the other hand, the TPR spectrum obtained from the 0.5 wt % CuO/{gamma}-Al{sub 2}O{sub 3} catalyst does not show any measurable H{sub 2} consumption up to 700 C, which suggests the presence of non-reducible isolated Cu species in this catalyst. STEM images collected from 10 wt % CuO/{gamma}-Al{sub 2}O{sub 3} show nano-sized CuO clusters, while no evidence of cluster formation is seen in the images recorded from the 0.5 wt % CuO/{gamma}-Al{sub 2}O{sub 3} sample, due to the intrinsic limitation of low Z contrast between highly dispersed Cu (atomic weight = 63.5) species and the alumina support (atomic weight of Al = 27). EXAFS data indicates the presence of Cu-Cu (Al) second shell at 0.35 nm only in the 10% CuO/{gamma}-Al{sub 2}O{sub 3} catalyst, and an estimated coordination number of {approx}1.7. The XANES and EXAFS results suggest the formation of relatively highly dispersed Cu oxide nanoclusters even at 10 wt % Cu loading. However, FT-IR spectra collected after CO adsorption on the CuO/{gamma}-Al{sub 2}O{sub 3} catalysts demonstrate the existence of different Cu species at Cu loadings of 0.5 and 10 wt %. Density functional theory (DFT) results show that supported CuO clusters, represented by a two-dimensional (2D) CuO monolayer, can effectively dissociate adsorbed NO and O2 to produce atomic oxygen species. These reactive atomic oxygen

  12. Phosphatidylinositol 5-phosphate 4-kinase type II beta is required for vitamin D receptor-dependent E-cadherin expression in SW480 cells

    International Nuclear Information System (INIS)

    Highlights: → We analyzed Phosphatidylinositol 5-phosphate kinase IIβ (PIPKIIβ) function in cancer. → PIPKIIβ is required for vitamin D receptor-mediated E-cadherin upregulation in SW480. → PIPKIIβ suppresses cellular motility through E-cadherin induction in SW480 cells. → Nuclear PIP2 but not plasma membrane-localized PIP2 mediates E-cadherin upregulation. -- Abstract: Numerous epidemiological data indicate that vitamin D receptor (VDR) signaling induced by its ligand or active metabolite 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) has anti-cancer activity in several colon cancers. 1α,25(OH)2D3 induces the epithelial differentiation of SW480 colon cancer cells expressing VDR (SW480-ADH) by upregulating E-cadherin expression; however, its precise mechanism remains unknown. We found that phosphatidylinositol-5-phosphate 4-kinase type II beta (PIPKIIβ) but not PIPKIIα is required for VDR-mediated E-cadherin induction in SW480-ADH cells. The syntenin-2 postsynaptic density protein/disc large/zona occludens (PDZ) domain and pleckstrin homology domain of phospholipase C-delta1 (PLCδ1 PHD) possess high affinity for phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) mainly localized to the nucleus and plasma membrane, respectively. The expression of syntenin-2 PDZ but not PLCδ1 PHD inhibited 1α,25(OH)2D3-induced E-cadherin upregulation, suggesting that nuclear PI(4,5)P2 production mediates E-cadherin expression through PIPKIIβ in a VDR-dependent manner. PIPKIIβ is also involved in the suppression of the cell motility induced by 1α,25(OH)2D3. These results indicate that PIPKIIβ-mediated PI(4,5)P2 signaling is important for E-cadherin upregulation and inhibition of cellular motility induced by VDR activation.

  13. Amphipathic silica nanoparticles induce cytotoxicity through oxidative stress mediated and p53 dependent apoptosis pathway in human liver cell line HL-7702 and rat liver cell line BRL-3A.

    Science.gov (United States)

    Zuo, Daiying; Duan, Zhenfang; Jia, Yuanyuan; Chu, Tianxue; He, Qiong; Yuan, Juan; Dai, Wei; Li, Zengqiang; Xing, Liguo; Wu, Yingliang

    2016-09-01

    The aim of this study was to evaluate the potential cytotoxicity and the underlying mechanism of amphipathic silica nanoparticles (SiO2 NPs) exposure to human normal liver HL-7702 cells and rat normal liver BRL-3A cells. Prior to the cellular studies, transmission electron microscopy (TEM), dynamic light scattering (DLS), and X ray diffraction (XRD) were used to characterize SiO2 NPs, which proved the amorphous nature of SiO2 NPs with TEM diameter of 19.8±2.7nm. Further studies proved that exposure to SiO2 NPs dose-dependently induced cytotoxicity as revealed by cell counting kit (CCK-8) and lactate dehydrogenase (LDH) assays, with more severe cytotoxicity in HL-7702 cells than BRL-3A cells. Reactive oxygen species (ROS) and glutathione (GSH) assays showed elevated oxidative stress in both cells. Morphological studies by microscopic observation, Hochest 33258 and AO/EB staining indicated significant apoptotic changes after the cells being exposed to SiO2 NPs. Further studies by western blot indicated that SiO2 NPs exposure to both cells up-regulated p53, Bax and cleaved caspase-3 expression and down-regulated Bcl-2 and caspase-3 levels. Activated caspase-3 activity detected by colorimetric assay kit and caspase-3/7 activity detected by fluorescent real-time detection kit were significantly increased by SiO2 NPs exposure. In addition, antioxidant vitamin C significantly attenuated SiO2 NPs-induced caspase-3 activation, which indicated that SiO2 NPs-induced oxidative stress was involved in the process of HL-7702 and BRL-3A cell apoptosis. Taken together, these results suggested that SiO2 NPs-induced cytotoxicity in HL-7702 and BRL-3A cells was through oxidative stress mediated and p53, caspase-3 and Bax/Bcl-2 dependent pathway and HL-7702 cells were more sensitive to SiO2 NPs-induced cytotoxicity than BRL-3A cells. PMID:27187187

  14. Symmetry-dependent interfacial reconstruction to compensate polar discontinuity at perovskite oxide interfaces (LaAlO3/SrTiO3 and LaAlO3/CaTiO3)

    International Nuclear Information System (INIS)

    We report the crystal symmetry-dependency of the interfacial reconstruction to relieve the polar discontinuity at the complex oxide heterointerfaces. We chose LaAlO3/SrTiO3 and LaAlO3/CaTiO3 interfaces as model systems, where the neutral TiO2 and the positive LaO+ layers form the polar discontinuity at the interface with TiO2-terminated (001) cubic SrTiO3 and orthorhombic CaTiO3. Using scanning transmission electron microscopy, we observed that the interlayer distance abnormally increased at the interface. We performed the first-principles calculations to understand the detailed atomic displacement at the interfaces having no oxygen vacancy and intermixing. Our results show that cations were reconstructed in different ways depending on the crystal symmetry through the octahedral tilts and atomic displacements to compensate the polar discontinuity at the interfaces. Our results imply that the interfacial reconstructions have to be considered along with the ionic compensation (intermixing) and electronic compensation (two dimensional electron gas) to fully understand the interfacial phenomena

  15. Symmetry-dependent interfacial reconstruction to compensate polar discontinuity at perovskite oxide interfaces (LaAlO{sub 3}/SrTiO{sub 3} and LaAlO{sub 3}/CaTiO{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joohwi; Moon, Seon Young; Kim, Jin-Sang; Choi, Jung-Hae, E-mail: choijh@kist.re.kr, E-mail: almacore@kist.re.kr [Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Choi, Jong Kwon [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Park, Jaehong [Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University, Seoul 151-744 (Korea, Republic of); Hwang, Cheol Seong [Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University, Seoul 151-744 (Korea, Republic of); Baek, Seung-Hyub [Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Nanomaterials Science and Technology, Korea University of Science and Technology, Daejeon 305-333 (Korea, Republic of); Chang, Hye Jung, E-mail: choijh@kist.re.kr, E-mail: almacore@kist.re.kr [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Nanomaterials Science and Technology, Korea University of Science and Technology, Daejeon 305-333 (Korea, Republic of)

    2015-02-16

    We report the crystal symmetry-dependency of the interfacial reconstruction to relieve the polar discontinuity at the complex oxide heterointerfaces. We chose LaAlO{sub 3}/SrTiO{sub 3} and LaAlO{sub 3}/CaTiO{sub 3} interfaces as model systems, where the neutral TiO{sub 2} and the positive LaO{sup +} layers form the polar discontinuity at the interface with TiO{sub 2}-terminated (001) cubic SrTiO{sub 3} and orthorhombic CaTiO{sub 3}. Using scanning transmission electron microscopy, we observed that the interlayer distance abnormally increased at the interface. We performed the first-principles calculations to understand the detailed atomic displacement at the interfaces having no oxygen vacancy and intermixing. Our results show that cations were reconstructed in different ways depending on the crystal symmetry through the octahedral tilts and atomic displacements to compensate the polar discontinuity at the interfaces. Our results imply that the interfacial reconstructions have to be considered along with the ionic compensation (intermixing) and electronic compensation (two dimensional electron gas) to fully understand the interfacial phenomena.

  16. Virulent but not Avirulent Mycobacterium tuberculosis Can Evade the Growth Inhibitory Action of a T Helper 1–dependent, Nitric Oxide Synthase 2–independent Defense in Mice

    Science.gov (United States)

    Jung, Yu-Jin; LaCourse, Ronald; Ryan, Lynn; North, Robert J.

    2002-01-01

    Control of infection with virulent Mycobacterium tuberculosis (Mtb) in mice is dependent on the generation of T helper (Th)1-mediated immunity that serves, via secretion of interferon (IFN)-γ and other cytokines, to upregulate the antimycobacterial function of macrophages of which the synthesis of inducible nitric oxide synthase (NOS)2 is an essential event. As a means to understanding the basis of Mtb virulence, the ability of gene-deleted mice incapable of making NOS2 (NOS2−/−), gp91Phox subunit of the respiratory burst NADPH-oxidase complex (Phox−/−), or either enzyme (NOS2/Phox−/−), to control airborne infection with the avirulent R1Rv and H37Ra strains of Mtb was compared with their ability control infection with the virulent H37Rv strain. NOS2−/−, Phox−/−, and NOS2/Phox−/− mice showed no deficiency in ability to control infection with either strain of avirulent Mtb. By contrast, NOS2−/− mice, but not Phox−/− mice, were incapable of controlling H37Rv infection and died early from neutrophil-dominated lung pathology. Control of infection with avirulent, as well as virulent Mtb, depended on the synthesis of IFN-γ, and was associated with a substantial increase in the synthesis in the lungs of mRNA for IFN-γ and NOS2, and with production of NOS2 by macrophages at sites of infection. The results indicate that virulent, but not avirulent, Mtb can overcome the growth inhibitory action of a Th1–dependent, NOS2-independent mechanism of defense. PMID:12370260

  17. The dependence of the oxidation state of vanadium on the oxygen pressure in melts of VOx, Na2O-VOx, and CaO-SiO2-VOx

    Science.gov (United States)

    Mittelstadt, Rainer; Schwerdtfeger, Klaus

    1990-02-01

    The oxidation state of vanadium has been determined as a function of oxygen pressure in pure VOx melts at 808 °C to 1000 °C, in Na2O-VOx melts with the initial molar ratios Na2O/V2O5 = 0.2, 0.5, and 1.0 at 1000 °C, and in CaO-SiO2-VOx melts with the molar ratios CaO/SiO2 = 0.71, 1.00, and 1.36 at 1600 °C. In the VOx melts, x is close to 2.5 in the range of oxygen pressure from P O 2 to 0.94 atm. The deviation, δ, from stoichiometric V2O5 (δ = 2.5- x) varies approximately proportionally to P O 2 -1/4, indicating an equilibrium between V4+ and V5+ ions. In the Na2O-VOx melts, and in the CaO-SiO2-VOx melts, x varies with log P O 2 according to an S-shaped function, with x approaching 1.5 at low and 2.5 at high oxygen pressures. At given oxygen pressures, x increases with Na2O or CaO content, respectively. Hence, these oxides stabilize the higher valent vanadium ions. For the CaO-SiO2-VOx system, the determined x- P O 2 dependence can be interpreted quantitatively in terms of V4+/V5+ and V3+/V4+ equilibria.

  18. Inhibition of autophagy promotes CYP2E1-dependent toxicity in HepG2 cells via elevated oxidative stress, mitochondria dysfunction and activation of p38 and JNK MAPK

    Directory of Open Access Journals (Sweden)

    Defeng Wu

    2013-01-01

    Full Text Available Autophagy has been shown to be protective against drug and alcohol-induced liver injury. CYP2E1 plays a role in the toxicity of ethanol, carcinogens and certain drugs. Inhibition of autophagy increased ethanol-toxicity and accumulation of fat in wild type and CYP2E1 knockin mice but not in CYP2E1 knockout mice as well as in HepG2 cells expressing CYP2E1 (E47 cells but not HepG2 cells lacking CYP2E1 (C34 cells. The goal of the current study was to evaluate whether modulation of autophagy can affect CYP2E1-dependent cytotoxicity in the E47 cells. The agents used to promote CYP2E1 –dependent toxicity were a polyunsaturated fatty acid, arachidonic acid (AA, buthionine sulfoximine (BSO, which depletes GSH, and CCl4, which is metabolized to the CCl3 radical. These three agents produced a decrease in E47 cell viability which was enhanced upon inhibition of autophagy by 3-methyladenine (3-MA or Atg 7 siRNA. Toxicity was lowered by rapamycin which increased autophagy and was much lower to the C34 cells which do not express CYP2E1. Toxicity was mainly necrotic and was associated with an increase in reactive oxygen production and oxidative stress; 3-MA increased while rapamycin blunted the oxidative stress. The enhanced toxicity and ROS formation produced when autophagy was inhibited was prevented by the antioxidant N-Acetyl cysteine. AA, BSO and CCl4 produced mitochondrial dysfunction, lowered cellular ATP levels and elevated mitochondrial production of ROS. This mitochondrial dysfunction was enhanced by inhibition of autophagy with 3-MA but decreased when autophagy was increased by rapamycin. The mitogen activated protein kinases p38 MAPK and JNK were activated by AA especially when autophagy was inhibited and chemical inhibitors of p38 MAPK and JNK lowered the elevated toxicity of AA produced by 3-MA. These results show that autophagy was protective against the toxicity produced by several agents known to be activated by CYP2E1. Since CYP2E1 plays an

  19. Exercise Dependence

    OpenAIRE

    Erdal Vardar

    1987-01-01

    Exercise dependence define a condition in which a person performs excessive exercise resulting in deterioration of his or her physical and mental health wellness. Despite many clinical research studies on exercise dependence, exact diagnostic criteria has not been developed yet. Clinical evidences concerning etiology, epidemiology, underlying mechanisms and treatment of exercise dependence are still not sufficient. Moreover, evaluation of this clinical disorder within dependency perspective i...

  20. Exercise Dependence

    OpenAIRE

    Vardar, Erdal

    2012-01-01

    Exercise dependence define a condition in which a person performs excessive exercise resulting in deterioration of his or her physical and mental health wellness. Despite many clinical research studies on exercise dependence, exact diagnostic criteria has not been developed yet. Clinical evidences concerning etiology, epidemiology, underlying mechanisms and treatment of exercise dependence are still not sufficient. Moreover, evaluation of this clinical disorder within dependency perspective...

  1. Excitotoxicity in the Lung: N-Methyl-D-Aspartate-Induced, Nitric Oxide-Dependent, Pulmonary Edema is Attenuated by Vasoactive Intestinal Peptide and by Inhibitors of Poly(ADP-Ribose) Polymerase

    Science.gov (United States)

    Said, Sami I.; Berisha, Hasan I.; Pakbaz, Hedayatollah

    1996-05-01

    Excitatory amino acid toxicity, resulting from overactivation of N-methyl-D-aspartate (NMDA) glutamate receptors, is a major mechanism of neuronal cell death in acute and chronic neurological diseases. We have investigated whether excitotoxicity may occur in peripheral organs, causing tissue injury, and report that NMDA receptor activation in perfused, ventilated rat lungs triggered acute injury, marked by increased pressures needed to ventilate and perfuse the lung, and by high-permeability edema. The injury was prevented by competitive NMDA receptor antagonists or by channel-blocker MK-801, and was reduced in the presence of Mg2+. As with NMDA toxicity to central neurons, the lung injury was nitric oxide (NO) dependent: it required L-arginine, was associated with increased production of NO, and was attenuated by either of two NO synthase inhibitors. The neuropeptide vasoactive intestinal peptide and inhibitors of poly(ADP-ribose) polymerase also prevented this injury, but without inhibiting NO synthesis, both acting by inhibiting a toxic action of NO that is critical to tissue injury. The findings indicate that: (i) NMDA receptors exist in the lung (and probably elsewhere outside the central nervous system), (ii) excessive activation of these receptors may provoke acute edematous lung injury as seen in the ``adult respiratory distress syndrome,'' and (iii) this injury can be modulated by blockade of one of three critical steps: NMDA receptor binding, inhibition of NO synthesis, or activation of poly(ADP-ribose) polymerase.

  2. Dependency Parsing

    CERN Document Server

    Kubler, Sandra; Nivre, Joakim

    2009-01-01

    Dependency-based methods for syntactic parsing have become increasingly popular in natural language processing in recent years. This book gives a thorough introduction to the methods that are most widely used today. After an introduction to dependency grammar and dependency parsing, followed by a formal characterization of the dependency parsing problem, the book surveys the three major classes of parsing models that are in current use: transition-based, graph-based, and grammar-based models. It continues with a chapter on evaluation and one on the comparison of different methods, and it close

  3. PREFACE: Semiconducting oxides Semiconducting oxides

    Science.gov (United States)

    Catlow, Richard; Walsh, Aron

    2011-08-01

    their help in producing this special section. We hope that it conveys some of the excitement and significance of the field. Semiconducting oxides contents Chemical bonding in copper-based transparent conducting oxides: CuMO2 (M = In, Ga, Sc) K G Godinho, B J Morgan, J P Allen, D O Scanlon and G W Watson Electrical properties of (Ba, Sr)TiO3 thin films with Pt and ITO electrodes: dielectric and rectifying behaviourShunyi Li, Cosmina Ghinea, Thorsten J M Bayer, Markus Motzko, Robert Schafranek and Andreas Klein Orientation dependent ionization potential of In2O3: a natural source for inhomogeneous barrier formation at electrode interfaces in organic electronicsMareike V Hohmann, Péter Ágoston, André Wachau, Thorsten J M Bayer, Joachim Brötz, Karsten Albe and Andreas Klein Cathodoluminescence studies of electron irradiation effects in n-type ZnOCasey Schwarz, Yuqing Lin, Max Shathkin, Elena Flitsiyan and Leonid Chernyak Resonant Raman scattering in ZnO:Mn and ZnO:Mn:Al thin films grown by RF sputteringM F Cerqueira, M I Vasilevskiy, F Oliveira, A G Rolo, T Viseu, J Ayres de Campos, E Alves and R Correia Structure and electrical properties of nanoparticulate tungsten oxide prepared by microwave plasma synthesisM Sagmeister, M Postl, U Brossmann, E J W List, A Klug, I Letofsky-Papst, D V Szabó and R Würschum Charge compensation in trivalent cation doped bulk rutile TiO2Anna Iwaszuk and Michael Nolan Deep level transient spectroscopy studies of n-type ZnO single crystals grown by different techniquesL Scheffler, Vl Kolkovsky, E V Lavrov and J Weber Microstructural and conductivity changes induced by annealing of ZnO:B thin films deposited by chemical vapour depositionC David, T Girardeau, F Paumier, D Eyidi, B Lacroix, N Papathanasiou, B P Tinkham, P Guérin and M Marteau Multi-component transparent conducting oxides: progress in materials modellingAron Walsh, Juarez L F Da Silva and Su-Huai Wei Thickness dependence of the strain, band gap and transport properties of

  4. MicroRNA-27b plays a role in pulmonary arterial hypertension by modulating peroxisome proliferator-activated receptor γ dependent Hsp90-eNOS signaling and nitric oxide production

    Energy Technology Data Exchange (ETDEWEB)

    Bi, Rui; Bao, Chunrong; Jiang, Lianyong; Liu, Hao; Yang, Yang; Mei, Ju; Ding, Fangbao, E-mail: dbcar126@126.com

    2015-05-01

    Pulmonary artery endothelial dysfunction is associated with pulmonary arterial hypertension (PAH). Based on recent studies showing that microRNA (miR)-27b is aberrantly expressed in PAH, we hypothesized that miR-27b may contribute to pulmonary endothelial dysfunction and vascular remodeling in PAH. The effect of miR-27b on pulmonary endothelial dysfunction and the underlying mechanism were investigated in human pulmonary artery endothelial cells (HPAECs) in vitro and in a monocrotaline (MCT)-induced model of PAH in vivo. miR-27b expression was upregulated in MCT-induced PAH and inversely correlated with the levels of peroxisome proliferator-activated receptor (PPAR)-γ, and miR-27b inhibition attenuated MCT-induced endothelial dysfunction and remodeling and prevented PAH associated right ventricular hypertrophy and systolic pressure in rats. PPARγ was confirmed as a direct target of miR-27b in HPAECs and shown to mediate the effect of miR-27b on the disruption of endothelial nitric oxide synthase (eNOS) coupling to Hsp90 and the suppression of NO production associated with the PAH phenotype. We showed that miR-27b plays a role endothelial function and NO release and elucidated a potential mechanism by which miR-27b regulates Hsp90-eNOS and NO signaling by modulating PPARγ expression, providing potential therapeutic targets for the treatment of PAH. - Highlights: • miR-27b plays a role in endothelial function and NO release. • miR-27b inhibition ameliorates MCT-induced endothelial dysfunction and PAH. • miR-27b targets PPARγ in HPAECs. • miR-27b regulates PPARγ dependent Hsp90-eNOS and NO signaling.

  5. Inhibition of Macrophage CD36 Expression and Cellular Oxidized Low Density Lipoprotein (oxLDL) Accumulation by Tamoxifen: A PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR (PPAR)γ-DEPENDENT MECHANISM.

    Science.gov (United States)

    Yu, Miao; Jiang, Meixiu; Chen, Yuanli; Zhang, Shuang; Zhang, Wenwen; Yang, Xiaoxiao; Li, Xiaoju; Li, Yan; Duan, Shengzhong; Han, Jihong; Duan, Yajun

    2016-08-12

    Macrophage CD36 binds and internalizes oxidized low density lipoprotein (oxLDL) to facilitate foam cell formation. CD36 expression is activated by peroxisome proliferator-activated receptor γ (PPARγ). Tamoxifen, an anti-breast cancer medicine, has demonstrated pleiotropic functions including cardioprotection with unfully elucidated mechanisms. In this study, we determined that treatment of ApoE-deficient mice with tamoxifen reduced atherosclerosis, which was associated with decreased CD36 and PPARγ expression in lesion areas. At the cellular level, we observed that tamoxifen inhibited CD36 protein expression in human THP-1 monocytes, THP-1/PMA macrophages, and human blood monocyte-derived macrophages. Associated with decreased CD36 protein expression, tamoxifen reduced cellular oxLDL accumulation in a CD36-dependent manner. At the transcriptional level, tamoxifen decreased CD36 mRNA expression, promoter activity, and the binding of the PPARγ response element in CD36 promoter to PPARγ protein. Tamoxifen blocked ligand-induced PPARγ nuclear translocation and CD36 expression, but it increased PPARγ phosphorylation, which was due to that tamoxifen-activated ERK1/2. Furthermore, deficiency of PPARγ expression in macrophages abolished the inhibitory effect of tamoxifen on CD36 expression or cellular oxLDL accumulation both in vitro and in vivo Taken together, our study demonstrates that tamoxifen inhibits CD36 expression and cellular oxLDL accumulation by inactivating the PPARγ signaling pathway, and the inhibition of macrophage CD36 expression can be attributed to the anti-atherogenic properties of tamoxifen. PMID:27358406

  6. MicroRNA-27b plays a role in pulmonary arterial hypertension by modulating peroxisome proliferator-activated receptor γ dependent Hsp90-eNOS signaling and nitric oxide production

    International Nuclear Information System (INIS)

    Pulmonary artery endothelial dysfunction is associated with pulmonary arterial hypertension (PAH). Based on recent studies showing that microRNA (miR)-27b is aberrantly expressed in PAH, we hypothesized that miR-27b may contribute to pulmonary endothelial dysfunction and vascular remodeling in PAH. The effect of miR-27b on pulmonary endothelial dysfunction and the underlying mechanism were investigated in human pulmonary artery endothelial cells (HPAECs) in vitro and in a monocrotaline (MCT)-induced model of PAH in vivo. miR-27b expression was upregulated in MCT-induced PAH and inversely correlated with the levels of peroxisome proliferator-activated receptor (PPAR)-γ, and miR-27b inhibition attenuated MCT-induced endothelial dysfunction and remodeling and prevented PAH associated right ventricular hypertrophy and systolic pressure in rats. PPARγ was confirmed as a direct target of miR-27b in HPAECs and shown to mediate the effect of miR-27b on the disruption of endothelial nitric oxide synthase (eNOS) coupling to Hsp90 and the suppression of NO production associated with the PAH phenotype. We showed that miR-27b plays a role endothelial function and NO release and elucidated a potential mechanism by which miR-27b regulates Hsp90-eNOS and NO signaling by modulating PPARγ expression, providing potential therapeutic targets for the treatment of PAH. - Highlights: • miR-27b plays a role in endothelial function and NO release. • miR-27b inhibition ameliorates MCT-induced endothelial dysfunction and PAH. • miR-27b targets PPARγ in HPAECs. • miR-27b regulates PPARγ dependent Hsp90-eNOS and NO signaling

  7. Towards monomaterial p-n junctions: Single-step fabrication of tin oxide films and their non-destructive characterisation by angle-dependent X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    The application of a non-destructive method for characterization of electronic structure of an ultra-thin SnO1dependent XPS, we quantified stoichiometry changes inside the SnO1oxide at the SnOx surface to a semiconducting one at the bottom of the SnOx film. The results showed that the application of a simple and cost-effective method allows tuning the materials' properties towards the one-step fabrication of materials with ambipolar doping

  8. Pro-survival effects of 17β-estradiol on osteocytes are mediated by nitric oxide/cGMP via differential actions of cGMP-dependent protein kinases I and II.

    Science.gov (United States)

    Marathe, Nisha; Rangaswami, Hema; Zhuang, Shunhui; Boss, Gerry R; Pilz, Renate B

    2012-01-01

    Estrogens promote bone health in part by increasing osteocyte survival, an effect that requires activation of the protein kinases Akt and ERK1/2, but the molecular mechanisms involved are only partly understood. Because estrogens increase nitric oxide (NO) synthesis and NO can have anti-apoptotic effects, we examined the role of NO/cGMP signaling in estrogen regulation of osteocyte survival. Etoposide-induced death of MLO-Y4 osteocyte-like cells, assessed by trypan blue staining, caspase-3 cleavage, and TUNEL assays, was completely prevented when cells were pre-treated with 17β-estradiol. This protective effect was mimicked when cells were pre-treated with a membrane-permeable cGMP analog and blocked by pharmacological inhibitors of NO synthase, soluble guanylate cyclase, or cGMP-dependent protein kinases (PKGs), supporting a requirement for NO/cGMP/PKG signaling downstream of 17β-estradiol. siRNA-mediated knockdown and viral reconstitution of individual PKG isoforms demonstrated that the anti-apoptotic effects of estradiol and cGMP were mediated by PKG Iα and PKG II. Akt and ERK1/2 activation by 17β-estradiol required PKG II, and cGMP mimicked the effects of estradiol on Akt and ERK, including induction of ERK nuclear translocation. cGMP induced BAD phosphorylation on several sites, and experiments with phosphorylation-deficient BAD mutants demonstrated that the anti-apoptotic effects of cGMP and 17β-estradiol required BAD phosphorylation on Ser(136) and Ser(155); these sites were targeted by Akt and PKG I, respectively, and regulate BAD interaction with Bcl-2. In conclusion, 17β-estradiol protects osteocytes against apoptosis by activating the NO/cGMP/PKG cascade; PKG II is required for estradiol-induced activation of ERK and Akt, and PKG Iα contributes to pro-survival signaling by directly phosphorylating BAD. PMID:22117068

  9. Nitric oxide triggers a concentration-dependent differential modulation of superoxide dismutase (FeSOD and Cu/ZnSOD) activity in sunflower seedling roots and cotyledons as an early and long distance signaling response to NaCl stress.

    Science.gov (United States)

    Arora, Dhara; Bhatla, Satish C

    2015-01-01

    Dark-grown sunflower (Helianthus annuus L.) seedlings exhibit modulation of total superoxide dismutase (SOD;EC 1.15.1.1) activity in roots and cotyledons (10,000g supernatant) in response to salt stress (NaCl; 120 mM) through a differential, zymographically detectable, whole tissue activity of FeSOD and Cu/ZnSOD. Confocal laser scanning microscopic imaging (CLSM) has further shown that NaCl stress significantly influences differential spatial distribution of Cu/ZnSOD and MnSOD isoforms in an inverse manner. Dual action of nitric oxide (NO) is evident in its crosstalk with FeSOD and Cu/ZnSOD in seedling roots and cotyledons in control and NaCl(-) stress conditions. Cu/ZnSOD activity in the roots of 2 d old NaCl(-) stressed seedlings is enhanced in the presence of 125-1000 µM of NO donor (sodium nitroprusside; SNP) indicating salt sensitivity of the enzyme activity. Quenching of endogenous NO by cPTIO treatment (500, 1000 µM) lowers FeSOD activity in roots (-NaCl). Cotyledons from control seedlings show an upregulation of FeSOD activity with increasing availability of SNP (125-1000 µM) in the Hoagland irrigation medium. Quenching of NO by cPTIO provides evidence for an inverse correlation between NO availability and FeSOD activity in seedling cotyledons irrespective of NaCl stress. Variable response due to NO on SOD isoforms in sunflower seedlings reflects its concentration-dependent biphasic (pro- and antioxidant) nature of action. Differential induction of SOD isoforms by NO indicates separate intracellular signaling pathways (associated with their respective functional separation) operative in seedling roots as an early salt stress mechanism and in cotyledons as an early long-distance NaCl stress sensing mechanism. PMID:26339977

  10. Towards monomaterial p-n junctions: Single-step fabrication of tin oxide films and their non-destructive characterisation by angle-dependent X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Krzywiecki, Maciej, E-mail: Maciej.Krzywiecki@polsl.pl [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Institute of Physics–CSE, Silesian University of Technology, Konarskiego 22B, 44-100 Gliwice (Poland); Sarfraz, Adnan; Erbe, Andreas [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany)

    2015-12-07

    The application of a non-destructive method for characterization of electronic structure of an ultra-thin SnO{sub 1dependent XPS, we quantified stoichiometry changes inside the SnO{sub 1oxide at the SnO{sub x} surface to a semiconducting one at the bottom of the SnO{sub x} film. The results showed that the application of a simple and cost-effective method allows tuning the materials' properties towards the one-step fabrication of materials with ambipolar doping.

  11. [Affective dependency].

    Science.gov (United States)

    Scantamburlo, G; Pitchot, W; Ansseau, M

    2013-01-01

    Affective dependency is characterized by emotional distress (insecure attachment) and dependency to another person with a low self-esteem and reassurance need. The paper proposes a reflection on the definition of emotional dependency and the confusion caused by various denominations. Overprotective and authoritarian parenting, cultural and socio-environmental factors may contribute to the development of dependent personality. Psychological epigenetic factors, such as early socio-emotional trauma could on neuronal circuits in prefronto-limbic regions that are essential for emotional behaviour.We also focus on the interrelations between dependent personality, domestic violence and addictions. The objective for the clinician is to propose a restoration of self-esteem and therapeutic strategies focused on autonomy. PMID:23888587

  12. 海洛因依赖者认知功能状况与一氧化氮等的关系%The relationship between cognitive function and the levels of serum nitric oxide and other oxidative stress indexes in patients with heroin dependence

    Institute of Scientific and Technical Information of China (English)

    李武; 胡春凤; 李龙飞; 王绪轶; 周旭辉; 郝伟

    2008-01-01

    Objective To explore the relationship between cognitive deficits and the levels of serum nitric oxide (NO) and other oxidative stress indexes in male patients with heroin dependence (MPHD). Methods Wechsler Memory Scale (WMS), Number Cancellation Test (NCT) and Modified Wisconsin Card Sorting Test (WCST) were employed to evaluate the cognitive function of 140 MPHD and 75 healthy controls. The levels of serum NO, malondialdehyde (MDA) and other oxidative stress indexes were detected by colorimetry. Results The memory quotient (MQ), attention and executive function in MPHD were significantly lower than that in healthy controls (P<0.05 or P<0.01). Compared with healthy controls, MPHD had higher serum MDA level but lower total antioxidative capability (T-AOC), vitamin C (VC) and superoxide dismutase (SOD) levels (P<0.05 or P<0.01). The serum NO level was negatively correlated to MQ and the card number of M-WCST sorted correctly (P<0.05 or P<0.01). The serum MDA level was negatively correlated to MQ, total net scores in NCT (P<0.01). The average value of serum VC showed significant association with MQ (P<0.05). Significant positive correlations were found between serum SOD level and MQ, total net scores in NCT, the card number sorted correctly (P<0.01).Conclusion MPHD suffered from cognitive dysfunction as well as oxidative and anti-oxidative unbalance. Serum NO, MDA, SOD and VC levels may be responsible for impaired cognition of MPHD.%目的 探讨海洛因依赖者认知功能受损与血清一氧化氮(NO)等的关系.方法 运用韦氏记忆量表(WMS)、数字划销测验(NCT)、威斯康星卡片分类测验(WCST)对140例男性海洛因依赖者(MPHD)及75例正常对照进行认知功能评估,用化学比色法检测受试血清NO等氧化应激指标水平.结果 (1)MPHD组记忆商(MQ)、注意力及执行功能均差于对照组;(2)血清丙二醛水平高于对照组, 总抗氧化能力、维生素C、超氧化物