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Sample records for ii-iii oxidation potential

  1. Benzylic oxidation catalyzed by dirhodium(II,III) caprolactamate.

    PubMed

    Catino, Arthur J; Nichols, Jason M; Choi, Hojae; Gottipamula, Sidhartha; Doyle, Michael P

    2005-11-10

    [reaction: see text] Dirhodium caprolactamate [Rh2(cap)4] is an effective catalyst for benzylic oxidation with tert-butyl hydroperoxide (TBHP) under mild conditions. Sodium bicarbonate is the optimal base additive for substrate conversion. Benzylic carbonyl compounds are readily obtained, and a formal synthesis of palmarumycin CP2 using this methodology is described.

  2. Abiotic selenium redox transformations in the presence of Fe(II,III) oxides

    SciTech Connect

    Myneni, S.C.B.; Tokunaga, T.K.; Brown, G.E. Jr.

    1997-11-07

    Many suboxic sediments and soils contain an Fe(II,III) oxide called green rust. Spectroscopic evidence showed that selenium reduces from an oxidation state of +VI to 0 in the presence of green rust at rates comparable with those found in sediments. Selenium speciation was different in solid and aqueous phases. These redox reactions represent an abiotic pathway for selenium cycling in natural environments, which has previously been considered to be mediated principally by microorganisms. Similar green rust-mediated abiotic redox reactions are likely to be involved in the mobility of several other trace elements and contaminants in the environment. 27 refs., 3 figs., 2 tabs.

  3. ARSENATE AND ARSENITE SORPTION AND ARSENITE OXIDATION BY IRON (II, III) HYDROXYCARBONATE GREEN RUST

    EPA Science Inventory

    Iron (II, III) hydroxycarbonate green rust is a major corrosion product of zerovalent iron that is being used in permeable reactive barriers to remediate groundwater arsenic contamination. To optimize the design of iron barriers, it is important to evaluate the influence of geoch...

  4. ARSENATE AND ARSENITE SORPTION AND ARSENITE OXIDATION BY IRON (II, III) HYDROXYCARBONATE GREEN RUST

    EPA Science Inventory

    Iron (II, III) hydroxycarbonate green rust is a major corrosion product of zerovalent iron that is being used in permeable reactive barriers to remediate groundwater arsenic contamination. To optimize the design of iron barriers, it is important to evaluate the influence of geoch...

  5. Comparative cytotoxicity and genotoxicity of cobalt (II, III) oxide, iron (III) oxide, silicon dioxide, and aluminum oxide nanoparticles on human lymphocytes in vitro.

    PubMed

    Rajiv, S; Jerobin, J; Saranya, V; Nainawat, M; Sharma, A; Makwana, P; Gayathri, C; Bharath, L; Singh, M; Kumar, M; Mukherjee, A; Chandrasekaran, N

    2016-02-01

    Despite the extensive use of nanoparticles (NPs) in various fields, adequate knowledge of human health risk and potential toxicity is still lacking. The human lymphocytes play a major role in the immune system, and it can alter the antioxidant level when exposed to NPs. Identification of the hazardous NPs was done using in vitro toxicity tests and this study mainly focuses on the comparative in vitro cytotoxicity and genotoxicity of four different NPs including cobalt (II, III) oxide (Co3O4), iron (III) oxide (Fe2O3), silicon dioxide (SiO2), and aluminum oxide (Al2O3) on human lymphocytes. The Co3O4 NPs showed decrease in cellular viability and increase in cell membrane damage followed by Fe2O3, SiO2, and Al2O3 NPs in a dose-dependent manner after 24 h of exposure to human lymphocytes. The oxidative stress was evidenced in human lymphocytes by the induction of reactive oxygen species, lipid peroxidation, and depletion of catalase, reduced glutathione, and superoxide dismutase. The Al2O3 NPs showed the least DNA damage when compared with all the other NPs. Chromosomal aberration was observed at 100 µg/ml when exposed to Co3O4 NPs and Fe2O3 NPs. The alteration in the level of antioxidant caused DNA damage and chromosomal aberration in human lymphocytes. © The Author(s) 2015.

  6. Oxidation modes and thermodynamics of Fe II-III oxyhydroxycarbonate green rust: Dissolution-precipitation versus in situ deprotonation

    NASA Astrophysics Data System (ADS)

    Ruby, Christian; Abdelmoula, Mustapha; Naille, Sébastien; Renard, Aurélien; Khare, Varsha; Ona-Nguema, Georges; Morin, Guillaume; Génin, Jean-Marie R.

    2010-02-01

    Fe II-III hydroxycarbonate green rust GR(CO 32-), Fe II4 Fe III2 (OH) 12 CO 3·3H 2O, is oxidized in aqueous solutions with varying reaction kinetics. Rapid oxidation with either H 2O 2 or dissolved oxygen under neutral and alkaline conditions leads to the formation of ferric oxyhydroxycarbonate GR(CO 32-)∗, Fe III6 O 12 H 8 CO 3·3H 2O, via a solid-state reaction. By decreasing the flow of oxygen bubbled in the solution, goethite α-FeOOH forms by dissolution-precipitation mechanism whereas a mixture of non-stoichiometric magnetite Fe (3-x)O 4 and goethite is observed for lower oxidation rates. The intermediate Fe II-III oxyhydroxycarbonate of formula Fe II6(1-x) Fe III6x O 12 H 2(7-3x) CO 3·3H 2O, i.e. GR( x)∗ for which x ɛ [1/3, 1], is the synthetic compound that is homologous to the fougerite mineral present in hydromorphic gleysol; in situ oxidation accounts for the variation of ferric molar fraction x = [Fe III]/{[Fe II]+[Fe III]} observed in the field as a function of depth and season but limited to the range [1/3, 2/3]. The domain of stability for partially oxidized green rust is observed in the Eh-pH Pourbaix diagrams if thermodynamic properties of GR( x)∗ is compared with those of lepidocrocite, γ-FeOOH, and goethite, α-FeOOH. Electrochemical equilibrium between GR( x)∗ and Fe II in solution corresponds to Eh-pH conditions close to those measured in the field. Therefore, the reductive dissolution of GR( x)∗ can explain the relatively large concentration of Fe II measured in aqueous medium of hydromorphic soils containing fougerite.

  7. Assessment of potential wood supply for intermediate scale thermoconversion facilities, Tasks I, II, III

    SciTech Connect

    Not Available

    1985-11-01

    The Department of Energy's Biomass Thermochemical Conversion Program has been concerned with the potential of wood biomass to contribute to the Nation's energy supply. One of the factors inhibiting the selection of wood biomass for energy by non-forest industries, especially by those requiring large quantities (500 to 2000 green tons per day), is concern with adequate fuel supply in terms of both a supply system and an adequate resource base. With respect to the latter, this report looks at the gross resource base as has been historically reported and also examines factors other than traditional product removals that could reduce to some degree the amount of resource that is available. The study also examined the conversion of a New England utility from coal to wood chips.

  8. Synthesis of iron(II,III) oxide/zinc oxide/copper(II) oxide (Fe3O4/ZnO/CuO) nanocomposites and their photosonocatalytic property for organic dye removal.

    PubMed

    Taufik, Ardiansyah; Saleh, Rosari

    2017-04-01

    A facile sol-gel method was adopted to synthesize iron(II,III) oxide/zinc oxide/copper(II) oxide (Fe3O4/ZnO/CuO) nanocomposites with various CuO loadings at a low temperature. The prepared nanocomposites were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV-Vis spectroscopy, vibrating sample magnetometry, and Brunauer-Emmett-Teller (BET) surface area analyses. The photosonocatalytic properties of the nanocomposites were tested by methylene blue removal in aqueous solutions under the combination of UV or visible light and ultrasound. The catalyst with the lowest CuO loading exhibited the highest photosonocatalytic performance under UV light, while the fastest degradation under visible light was achieved at the highest CuO loading. Overall, the photosonocatalytic process with light and ultrasound irradiation led to more complete degradation compared to using light alone. According to the experiments performed with radical scavengers, the holes and OH radicals are the dominant oxidative species. The nanocomposites can be easily separated from the treated solution using an external magnetic field, and the samples remain very stable after 4 cycles. These results indicate that these materials have great potential for treating organic pollutants in wastewaters.

  9. Oxidation-Responsive, EuII/III-Based, Multimodal Contrast Agent for Magnetic Resonance and Photoacoustic Imaging

    PubMed Central

    2017-01-01

    We report, for the first time, a multimodal, oxidation-responsive contrast agent for magnetic resonance imaging and photoacoustic imaging that uses the differences in the properties between Eu in the +2 and +3 oxidation states. The enhancement of contrast in T1-weighted magnetic resonance and photoacoustic imaging was observed in the +2 but not in the +3 oxidation state, and the complex is a known chemical exchange saturation transfer agent for magnetic resonance imaging in the +3 oxidation state. PMID:28393130

  10. Mn(II,III) oxidation and MnO2 mineralization by an expressed bacterial multicopper oxidase

    SciTech Connect

    Butterfield, Cristina N.; Soldatova, Alexandra V.; Lee, Sung -Woo; Spiro, Thomas G.; Tebo, Bradley M.

    2013-07-01

    Reactive Mn(IV) oxide minerals are ubiquitous in the environment and control the bioavailability and distribution of many toxic and essential elements and organic compounds. Their formation is thought to be dependent on microbial enzymes, because spontaneous Mn(II) to Mn(IV) oxidation is slow. Several species of marine Bacillus spores oxidize Mn(II) on their exosporium, the outermost layer of the spore, encrusting them with Mn(IV) oxides. Molecular studies have identified the mnx (Mn oxidation) genes, including mnxG, encoding a putative multicopper oxidase (MCO), as responsible for this two-electron oxidation, a surprising finding because MCOs only catalyze single-electron transfer reactions. Characterization of the enzymatic mechanism has been hindered by the lack of purified protein. By purifying active protein from the mnxDEFG expression construct, we found that the resulting enzyme is a blue (absorption maximum 590 nm) complex containing MnxE, MnxF, and MnxG proteins. Further, by analyzing the Mn(II)- and (III)-oxidizing activity in the presence of a Mn(III) chelator, pyrophosphate, we found that the complex facilitates both electron transfers from Mn(II) to Mn(III) and from Mn(III) to Mn(IV). X-ray absorption spectroscopy of the Mn mineral product confirmed its similarity to Mn(IV) oxides generated by whole spores. Our results demonstrate that Mn oxidation from soluble Mn(II) to Mn(IV) oxides is a two-step reaction catalyzed by an MCO-containing complex. Lastly, with the purification of active Mn oxidase, we will be able to uncover its mechanism, broadening our understanding of Mn mineral formation and the bioinorganic capabilities of MCOs.

  11. Mn(II,III) oxidation and MnO2 mineralization by an expressed bacterial multicopper oxidase

    PubMed Central

    Butterfield, Cristina N.; Soldatova, Alexandra V.; Lee, Sung-Woo; Spiro, Thomas G.; Tebo, Bradley M.

    2013-01-01

    Reactive Mn(IV) oxide minerals are ubiquitous in the environment and control the bioavailability and distribution of many toxic and essential elements and organic compounds. Their formation is thought to be dependent on microbial enzymes, because spontaneous Mn(II) to Mn(IV) oxidation is slow. Several species of marine Bacillus spores oxidize Mn(II) on their exosporium, the outermost layer of the spore, encrusting them with Mn(IV) oxides. Molecular studies have identified the mnx (Mn oxidation) genes, including mnxG, encoding a putative multicopper oxidase (MCO), as responsible for this two-electron oxidation, a surprising finding because MCOs only catalyze single-electron transfer reactions. Characterization of the enzymatic mechanism has been hindered by the lack of purified protein. By purifying active protein from the mnxDEFG expression construct, we found that the resulting enzyme is a blue (absorption maximum 590 nm) complex containing MnxE, MnxF, and MnxG proteins. Further, by analyzing the Mn(II)- and (III)-oxidizing activity in the presence of a Mn(III) chelator, pyrophosphate, we found that the complex facilitates both electron transfers from Mn(II) to Mn(III) and from Mn(III) to Mn(IV). X-ray absorption spectroscopy of the Mn mineral product confirmed its similarity to Mn(IV) oxides generated by whole spores. Our results demonstrate that Mn oxidation from soluble Mn(II) to Mn(IV) oxides is a two-step reaction catalyzed by an MCO-containing complex. With the purification of active Mn oxidase, we will be able to uncover its mechanism, broadening our understanding of Mn mineral formation and the bioinorganic capabilities of MCOs. PMID:23818588

  12. Mn(II,III) oxidation and MnO2 mineralization by an expressed bacterial multicopper oxidase

    DOE PAGES

    Butterfield, Cristina N.; Soldatova, Alexandra V.; Lee, Sung -Woo; ...

    2013-07-01

    Reactive Mn(IV) oxide minerals are ubiquitous in the environment and control the bioavailability and distribution of many toxic and essential elements and organic compounds. Their formation is thought to be dependent on microbial enzymes, because spontaneous Mn(II) to Mn(IV) oxidation is slow. Several species of marine Bacillus spores oxidize Mn(II) on their exosporium, the outermost layer of the spore, encrusting them with Mn(IV) oxides. Molecular studies have identified the mnx (Mn oxidation) genes, including mnxG, encoding a putative multicopper oxidase (MCO), as responsible for this two-electron oxidation, a surprising finding because MCOs only catalyze single-electron transfer reactions. Characterization of themore » enzymatic mechanism has been hindered by the lack of purified protein. By purifying active protein from the mnxDEFG expression construct, we found that the resulting enzyme is a blue (absorption maximum 590 nm) complex containing MnxE, MnxF, and MnxG proteins. Further, by analyzing the Mn(II)- and (III)-oxidizing activity in the presence of a Mn(III) chelator, pyrophosphate, we found that the complex facilitates both electron transfers from Mn(II) to Mn(III) and from Mn(III) to Mn(IV). X-ray absorption spectroscopy of the Mn mineral product confirmed its similarity to Mn(IV) oxides generated by whole spores. Our results demonstrate that Mn oxidation from soluble Mn(II) to Mn(IV) oxides is a two-step reaction catalyzed by an MCO-containing complex. Lastly, with the purification of active Mn oxidase, we will be able to uncover its mechanism, broadening our understanding of Mn mineral formation and the bioinorganic capabilities of MCOs.« less

  13. Decoration of the layered manganese oxide birnessite with Mn(II/III) gives a new water oxidation catalyst with fifty-fold turnover number enhancement.

    PubMed

    McKendry, Ian G; Kondaveeti, Sandeep K; Shumlas, Samantha L; Strongin, Daniel R; Zdilla, Michael J

    2015-08-07

    The role of the manganese average oxidation state (AOS) in water oxidation catalysis by birnessite was investigated. Low AOS samples were most active, generating O2 immediately. Samples with a relatively high AOS showed an initial induction period and decreased turnover. Mn(ii- and iii)-enriched samples gave a 10-50 fold enhancement in turnover number.

  14. Mn(II) Oxidation by the Multicopper Oxidase Complex Mnx: A Coordinated Two-Stage Mn(II)/(III) and Mn(III)/(IV) Mechanism.

    PubMed

    Soldatova, Alexandra V; Romano, Christine A; Tao, Lizhi; Stich, Troy A; Casey, William H; Britt, R David; Tebo, Bradley M; Spiro, Thomas G

    2017-08-23

    The bacterial manganese oxidase MnxG of the Mnx protein complex is unique among multicopper oxidases (MCOs) in carrying out a two-electron metal oxidation, converting Mn(II) to MnO2 nanoparticles. The reaction occurs in two stages: Mn(II) → Mn(III) and Mn(III) → MnO2. In a companion study , we show that the electron transfer from Mn(II) to the low-potential type 1 Cu of MnxG requires an activation step, likely forming a hydroxide bridge at a dinuclear Mn(II) site. Here we study the second oxidation step, using pyrophosphate (PP) as a Mn(III) trap. PP chelates Mn(III) produced by the enzyme and subsequently allows it to become a substrate for the second stage of the reaction. EPR spectroscopy confirms the presence of Mn(III) bound to the enzyme. The Mn(III) oxidation step does not involve direct electron transfer to the enzyme from Mn(III), which is shown by kinetic measurements to be excluded from the Mn(II) binding site. Instead, Mn(III) is proposed to disproportionate at an adjacent polynuclear site, thereby allowing indirect oxidation to Mn(IV) and recycling of Mn(II). PP plays a multifaceted role, slowing the reaction by complexing both Mn(II) and Mn(III) in solution, and also inhibiting catalysis, likely through binding at or near the active site. An overall mechanism for Mnx-catalyzed MnO2 production from Mn(II) is presented.

  15. Elimination of manganese(II,III) oxidation in Pseudomonas putida GB-1 by a double knockout of two putative multicopper oxidase genes.

    PubMed

    Geszvain, Kati; McCarthy, James K; Tebo, Bradley M

    2013-01-01

    Bacterial manganese(II) oxidation impacts the redox cycling of Mn, other elements, and compounds in the environment; therefore, it is important to understand the mechanisms of and enzymes responsible for Mn(II) oxidation. In several Mn(II)-oxidizing organisms, the identified Mn(II) oxidase belongs to either the multicopper oxidase (MCO) or the heme peroxidase family of proteins. However, the identity of the oxidase in Pseudomonas putida GB-1 has long remained unknown. To identify the P. putida GB-1 oxidase, we searched its genome and found several homologues of known or suspected Mn(II) oxidase-encoding genes (mnxG, mofA, moxA, and mopA). To narrow this list, we assumed that the Mn(II) oxidase gene would be conserved among Mn(II)-oxidizing pseudomonads but not in nonoxidizers and performed a genome comparison to 11 Pseudomonas species. We further assumed that the oxidase gene would be regulated by MnxR, a transcription factor required for Mn(II) oxidation. Two loci met all these criteria: PputGB1_2447, which encodes an MCO homologous to MnxG, and PputGB1_2665, which encodes an MCO with very low homology to MofA. In-frame deletions of each locus resulted in strains that retained some ability to oxidize Mn(II) or Mn(III); loss of oxidation was attained only upon deletion of both genes. These results suggest that PputGB1_2447 and PputGB1_2665 encode two MCOs that are independently capable of oxidizing both Mn(II) and Mn(III). The purpose of this redundancy is unclear; however, differences in oxidation phenotype for the single mutants suggest specialization in function for the two enzymes.

  16. Manganese leads to an increase in markers of oxidative stress as well as to a shift in the ratio of Fe(II)/(III) in rat brain tissue.

    PubMed

    Fernsebner, Katharina; Zorn, Julia; Kanawati, Basem; Walker, Alesia; Michalke, Bernhard

    2014-04-01

    Occupationally or environmentally caused chronic exposure to Manganese (Mn) can lead to a degeneration of dopaminergic neurons inducing a Parkinson-like complaint called manganism. Deciphering the ongoing neurodegenerative mechanisms in the affected brain is still a major task for understanding the complex modes of action. Therefore, we applied a non-toxic, oral feeding in rats simulating a chronic exposure to Mn. Analysis of brain extracts by electrospray ionization Fourier transform resonance mass spectrometry (ESI-FT-ICR-MS) revealed an increase in markers of oxidative stress like glutathione disulfide (GSSG), prostaglandins, and 15(S)-HETE, a marker of lipid peroxidation. Furthermore, acetylcholinesterase (AchE) activity and glutamate concentrations were elevated in brain samples of Mn-supplemented rats, suggesting oxidative stress in the brain tissue. Application of ion chromatography coupled to inductively coupled plasma-optical emission spectrometry (IC-ICP-OES) further showed a shift of Fe(III) towards Fe(II) in the brain samples enabling for example the action of the Fenton reaction. This is the first time that changes in the Fe-species distribution could be related to Mn-induced neuroinflammation and is therefore enlarging the knowledge of this complex neurodegenerative condition. The combination of our findings provides substantial evidence that Mn-induced neuroinflammation leads to oxidative stress triggered by multifactorial pathophysiological processes.

  17. Synthesis, characterization and application of iron (II, III) oxide (Fe3O4) magnetic nanoparticles in mimic of wound healing model

    NASA Astrophysics Data System (ADS)

    Konyala, Divya

    The research study focused on synthesis, characterization and applications of Fe3O4 core-shelled magnetic nanomaterials. This Fe3O4 magnetic nanomaterials will be prepared by using cost effective and convenient wet-chemistry method and will encapsulated using aqueous extracts of medicinal natural products. Three natural products namely Symplocos racemosa, Picrorhiza kurroa and Butea monosperma used to encapsulate Fe3O 4 MNMs due to their scope to reduce the risk of cancer, improves health, increase energy and enhance the immunity. These three medicinal natural products are synthesize by using water as a solvents to derive its active constituents, which will further used to functionalize the magnetic nanomaterials. The magnetic nanoparticles characterization studies performed using X-ray powder diffraction, Scanning electron microscope, Transmission electron microscope, Ultraviolet-visible spectroscopy, Fourier Transform Infrared spectroscopy (FT-IR) and Magnetic property. Fe3O4 magnetic nanomaterials biological activity was tested on Gram-negative bacteria (Escherichia coli). The results pointed out that, due to the adequate coating of Fe 3O4 (Iron Oxide) core by the medicinal chemical constituents from the natural products, the absorption of Fe3O4 magnetic nanomaterials was not detected in the UV-VIS Spectroscopy. TEM images showed that Fe3O4 coated with natural product extract in core-shelled structure, and the size of the particle ranges from 6 nm to 10 nm. Fourier Transform Infrared spectroscopy (FT-IR) was performed to determine the nature of chemicals present in natural extracts and functionalized Fe3O 4 magnetic nanomaterials. The model of wound healing mimic and antibacterial activity performed on gram-negative (Escherichia coli), indicating steady increasing cell growth after adding Fe3O4 MNMs. It was also found that MNMs synthesized at high temperatures shows less wound healing activity, when compared to MNMs prepared at room temperature due to formation

  18. A new direction in dye-sensitized solar cells redox mediator development: in situ fine-tuning of the cobalt(II)/(III) redox potential through Lewis base interactions.

    PubMed

    Kashif, Muhammad K; Axelson, Jordan C; Duffy, Noel W; Forsyth, Craig M; Chang, Christopher J; Long, Jeffrey R; Spiccia, Leone; Bach, Udo

    2012-10-10

    Dye-sensitized solar cells (DSCs) are an attractive renewable energy technology currently under intense investigation. In recent years, one area of major interest has been the exploration of alternatives to the classical iodide/triiodide redox shuttle, with particular attention focused on cobalt complexes with the general formula [Co(L)(n)](2+/3+). We introduce a new approach to designing redox mediators that involves the application of [Co(PY5Me(2))(MeCN)](2+/3+) complexes, where PY5Me(2) is the pentadentate ligand, 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine. It is shown, by X-ray crystallography, that the axial acetonitrile (MeCN) ligand can be replaced by more strongly coordinating Lewis bases (B) to give complexes with the general formula [Co(PY5Me(2))(B)](2+/3+), where B = 4-tert-butylpyridine (tBP) or N-methylbenzimidazole (NMBI). These commonly applied DSC electrolyte components are used for the first time to fine-tune the potential of the redox couple to the requirements of the dye through coordinative interactions with the Co(II/III) centers. Application of electrolytes based on the [Co(PY5Me(2))(NMBI)](2+/3+) complex in combination with a commercially available organic sensitizer has enabled us to attain DSC efficiencies of 8.4% and 9.2% at a simulated light intensity of 100% sun (1000 W m(-2) AM1.5 G) and at 10% sun, respectively, higher than analogous devices applying the [Co(bpy)(3)](2+/3+) redox couple, and an open circuit voltage (V(oc)) of almost 1.0 V at 100% sun for devices constructed with the tBP complex.

  19. Mn(II/III) complexes as promising redox mediators in quantum-dot-sensitized solar cells.

    PubMed

    Haring, Andrew J; Pomatto, Michelle E; Thornton, Miranda R; Morris, Amanda J

    2014-09-10

    The advancement of quantum dot sensitized solar cell (QDSSC) technology depends on optimizing directional charge transfer between light absorbing quantum dots, TiO2, and a redox mediator. The nature of the redox mediator plays a pivotal role in determining the photocurrent and photovoltage from the solar cell. Kinetically, reduction of oxidized quantum dots by the redox mediator should be rapid and faster than the back electron transfer between TiO2 and oxidized quantum dots to maintain photocurrent. Thermodynamically, the reduction potential of the redox mediator should be sufficiently positive to provide high photovoltages. To satisfy both criteria and enhance power conversion efficiencies, we introduced charge transfer spin-crossover Mn(II/III) complexes as promising redox mediator alternatives in QDSSCs. High photovoltages ∼ 1 V were achieved by a series of Mn poly(pyrazolyl)borates, with reduction potentials ∼ 0.51 V vs Ag/AgCl. Back electron transfer (recombination) rates were slower than Co(bpy)3, where bpy = 2,2'-bipyridine, evidenced by electron lifetimes up to 4 orders of magnitude longer. This is indicative of a large barrier to electron transport imposed by spin-crossover in these complexes. Low solubility prevented the redox mediators from sustaining high photocurrent due to mass transport limits. However, with high fill factors (∼ 0.6) and photovoltages, they demonstrate competitive efficiencies with Co(bpy)3 redox mediator at the same concentration. More positive reduction potentials and slower recombination rates compared to current redox mediators establish the viability of Mn poly(pyrazolyl)borates as promising redox mediators. By capitalizing on these characteristics, efficient Mn(II/III)-based QDSSCs can be achieved with more soluble Mn-complexes.

  20. Ethylene oxide potential toxicity.

    PubMed

    da Cunha Mendes, Gisela Cristina; da Silva Brandão, Teresa Ribeiro; Miranda Silva, Cristina Luisa

    2008-05-01

    The future of ethylene oxide (EO) sterilization has been questioned, owing to its associated toxicity. EO has been around for more than 60 years, mainly due to its recognized characteristics of reliability and effectiveness, coupled with the process flexibility, as well as its compatibility with most mechanical devices. Despite the well-known EO toxicity, the undesirable effects of medical devices' EO residues on the patient's health have not yet been well established. There are limitations related to the current risk-assessment studies. To overcome these drawbacks, demands on greater safety are increasing, which lead to improvements in sterilizers and aeration equipment, as well as the design of the processes. The paper under evaluation highlights risks related to EO sterilization of materials used during processing of stem cells for transplantation, but is an example of a study where the dose of the residues in the devices is not considered.

  1. Properties of Lanthanide Hydroxide Molecules Produced in Reactions of Lanthanide Atoms with H2O2 and H2 + O2 Mixtures: Roles of the +I, +II, +III, and +IV Oxidation States.

    PubMed

    Wang, Xuefeng; Andrews, Lester; Fang, Zongtang; Thanthiriwatte, K Sahan; Chen, Mingyang; Dixon, David A

    2017-03-02

    The reactions of laser-ablated lanthanide metal atoms with hydrogen peroxide or hydrogen plus oxygen mixtures have been studied experimentally in a solid argon matrix and theoretically with the ab initio MP2 and CCSD(T) methods. The Ln(OH)3 and Ln(OH)2 molecules and Ln(OH)2(+) cations are the major products, and the reactions to form those hydroxides are predicted to be highly exothermic at the CCSD(T) level. Vibronic interactions are hypothesized to contribute to the abnormalities in deuterium shifts for Ln-OH(D) stretching modes for several hydroxides, consistent with CASSCF calculations. Additional new absorptions were assigned as HLnO or LnOH and OLnOH molecules. The tetrahydroxides of Ce, Pr, and Tb have also been observed. These reactive intermediates were identified from their matrix infrared spectra by using D2O2, HD, D2, (16,18)O2, and (18)O2 isotopic substitution, by matching observed frequencies with values calculated by electronic structure methods, and by following the trends observed in frequencies going through different lanthanide metal hydroxide series across the periodic table. The lanthanides are in the +II oxidation state for Ln(OH)2 and are in the +III oxidation state for Ln(OH)3 and Ln(OH)2(+).

  2. Recent Advances of Cobalt(II/III) Redox Couples for Dye-Sensitized Solar Cell Applications.

    PubMed

    Giribabu, Lingamallu; Bolligarla, Ramababu; Panigrahi, Mallika

    2015-08-01

    In recent years dye-sensitized solar cells (DSSCs) have emerged as one of the alternatives for the global energy crisis. DSSCs have achieved a certified efficiency of >11% by using the I(-) /I3 (-) redox couple. In order to commercialize the technology almost all components of the device have to be improved. Among the various components of DSSCs, the redox couple that regenerates the oxidized sensitizer plays a crucial role in achieving high efficiency and durability of the cell. However, the I(-) /I3 (-) redox couple has certain limitations such as the absorption of triiodide up to 430 nm and the volatile nature of iodine, which also corrodes the silver-based current collectors. These limitations are obstructing the commercialization of this technology. For this reason, one has to identify alternative redox couples. In this regard, the Co(II/III) redox couple is found to be the best alternative to the existing I(-) /I3 (-) redox couple. Recently, DSSC test cell efficiency has risen up to 13% by using the cobalt redox couple. This review emphasizes the recent development of Co(II/III) redox couples for DSSC applications.

  3. Cholinergic suppression of excitatory synaptic transmission in layers II/III of the parasubiculum.

    PubMed

    Glasgow, S D; Glovaci, I; Karpowicz, L S; Chapman, C A

    2012-01-10

    Layer II of the parasubiculum (PaS) receives excitatory synaptic input from the CA1 region of the hippocampus and sends a major output to layer II of the medial and lateral entorhinal cortex. The PaS also receives heavy cholinergic innervation from the medial septum, which contributes to the generation of theta-frequency (4-12 Hz) electroencephalographic (EEG) activity. Cholinergic receptor activation exerts a wide range of effects in other areas of the hippocampal formation, including membrane depolarization, changes in neuronal excitability, and suppression of excitatory synaptic responses. The present study was aimed at determining how cholinergic receptor activation modulates excitatory synaptic input to the layer II/III neurons of the PaS in acute brain slices. Field excitatory postsynaptic potentials (fEPSPs) in layer II/III of the PaS were evoked by stimulation of either layer I afferents, or ascending inputs from layer V. Bath-application of the cholinergic agonist carbachol (0.5-10 μM) suppressed the amplitude of fEPSPs evoked by both superficial- and deep layer stimulation, and also enhanced paired-pulse facilitation. Constant bath-application of the GABA(A) antagonist bicuculline (10 μM) failed to eliminate the suppression, indicating that the cholinergic suppression of fEPSPs is not due to increased inhibitory tone. The muscarinic receptor antagonist atropine (1 μM) blocked the suppression of fEPSPs, and the selective M(1)-preferring receptor antagonist pirenzepine (1 μM), but not the M(2)-preferring antagonist methoctramine (1-5 μM), also significantly attenuated the suppression. Therefore, cholinergic receptor activation suppresses excitatory synaptic input to layer II/III neurons of the PaS, and this suppression is mediated in part by M(1) receptor activation.

  4. Kinetics and Products of Chromium(VI) Reduction by Iron(II/III)-Bearing Clay Minerals.

    PubMed

    Joe-Wong, Claresta; Brown, Gordon E; Maher, Kate

    2017-09-05

    Hexavalent chromium is a water-soluble pollutant, the mobility of which can be controlled by reduction of Cr(VI) to less soluble, environmentally benign Cr(III). Iron(II/III)-bearing clay minerals are widespread potential reductants of Cr(VI), but the kinetics and pathways of Cr(VI) reduction by such clay minerals are poorly understood. We reacted aqueous Cr(VI) with two abiotically reduced clay minerals: an Fe-poor montmorillonite and an Fe-rich nontronite. The effects of ionic strength, pH, total Fe content, and the fraction of reduced structural Fe(II) [Fe(II)/Fe(total)] were examined. The last variable had the largest effect on Cr(VI) reduction kinetics: for both clay minerals, the rate constant of Cr(VI) reduction varies by more than 3 orders of magnitude with Fe(II)/Fe(total) and is described by a linear free energy relationship. Under all conditions examined, Cr and Fe K-edge X-ray absorption near-edge structure spectra show that the main Cr-bearing product is a Cr(III)-hydroxide and that Fe remains in the clay structure after reacting with Cr(VI). This study helps to quantify our understanding of the kinetics of Cr(VI) reduction by Fe(II/III)-bearing clay minerals and may improve predictions of Cr(VI) behavior in subsurface environments.

  5. Diruthenium(II,III) tetramidates as a new class of oxygenation catalysts.

    PubMed

    Villalobos, Leslie; Cao, Zhi; Fanwick, Phillip E; Ren, Tong

    2012-01-14

    Two new diruthenium(II,III) tetramidate compounds, Ru(2)(NHOCC(CH(3))(2))(4)Cl (1) and Ru(2)(NHOCCH(2)CH(3))(4)Cl (2) have been prepared and structurally characterized by X-ray crystallography. The activity of promoting sulfide oxygenation using simple oxidants such as hydrogen peroxide (H(2)O(2)) and tert-butyl hydroperoxide (TBHP) was studied. A UV-kinetics study indicated that the initial rates of 1 and 2 are comparable to the previously studied diruthenium tetracarboxylates in promoting TBHP oxygenation of methyl phenyl sulfide (MPS). Using excess oxidant and CH(3)CN as the solvent, organic sulfides MPS and diphenyl sulfide (PPS) were oxidized using 1 mol% of the catalytic species. Compound 1 is more effective than 2 in converting sulfides to sulfoxide under the same conditions. Fast conversion was achieved when the reactions were carried out in the solvent-free conditions, and the major oxidation product was the sulfoxide. The electronic structure of the title compounds was studied with DFT calculations to gain an understanding of the activation of peroxy reagents.

  6. Resonant L{sub II,III} x-ray Raman scattering from HCl

    SciTech Connect

    Saathe, C.; Rubensson, J.-E.; Nordgren, J.; Guimaraes, F. F.; Agui, A.; Guo, J.; Ekstroem, U.; Norman, P.; Gel'mukhanov, F.; Aagren, H.

    2006-12-15

    We have studied the spectral features of Cl L{sub II,III} resonant x-ray Raman scattering of HCl molecules in gas phase both experimentally and theoretically. The theory, formulated in the intermediate-coupling scheme, takes into account the spin-orbital and molecular-field splittings in the Cl 2p shells, as well as the Coulomb interaction of the core hole with unoccupied molecular orbitals. Experiment and theory display nondispersive dissociative peaks formed by decay transitions in both molecular and dissociative regions. The molecular and atomic peaks collapse in a single narrow resonance because the dissociative potentials of core-excited and final states are parallel to each other along the whole pathway of the nuclear wave packet.

  7. ARSENIC INTERACTION WITH IRON (II, III) HYDROXYCARBONATE GREEN RUST: IMPLICATIONS FOR ARSENIC REMEDIATION

    EPA Science Inventory

    Zerovalent iron is being used in permeable reactive barriers (PRBs) to remediate groundwater arsenic contamination. Iron(II, III) hydroxycarbonate green rust is a major corrosion product of zerovalent iron under anaerobic conditions. The interaction between arsenic and this green...

  8. ARSENIC INTERACTION WITH IRON (II, III) HYDROXYCARBONATE GREEN RUST: IMPLICATIONS FOR ARSENIC REMEDIATION

    EPA Science Inventory

    Zerovalent iron is being used in permeable reactive barriers (PRBs) to remediate groundwater arsenic contamination. Iron(II, III) hydroxycarbonate green rust is a major corrosion product of zerovalent iron under anaerobic conditions. The interaction between arsenic and this green...

  9. tert-Butyl hydroperoxide oxygenation of organic sulfides catalyzed by diruthenium(II,III) tetracarboxylates.

    PubMed

    Villalobos, Leslie; Barker Paredes, Julia E; Cao, Zhi; Ren, Tong

    2013-11-04

    Diruthenium(II,III) carboxylates Ru2(esp)2Cl (1a), [Ru2(esp)2(H2O)2]BF4 (1b), and Ru2(OAc)4Cl (2) efficiently catalyze the oxygenation of organic sulfides. As noted in a previous work, 1a is active in oxygenation of organic sulfides with tert-butyl hydroperoxide (TBHP) in CH3CN. Reported herein in detail is the oxygenation activity of 1a, 1b, and 2, with the latter being highly selective in oxo-transfer to organic sulfides using TBHP under ambient conditions. Solvent-free oxidation reactions were achieved through dissolving 1a or 1b directly into the substrate with 2 equiv of TBHP, yielding TOF up to 2056 h(-1) with 1b. Also examined are the rate dependence on both catalyst and oxidant concentration for reactions with catalysts 1a and 2. Ru2(OAc)4Cl may be kinetically saturated with TBHP; however, Ru2(esp)2Cl does not display saturation kinetics. By use of a series of para-substituted thioanisoles, linear free-energy relationships were established for both 1a and 2, where the reactivity constants (ρ) are negative and that of 1a is about half that of 2. Given these reactivity data, two plausible reaction pathways were suggested. Density functional theory (DFT) calculation for the model compound Ru2(OAc)4Cl·TBHP, with TBHP on the open axial site, revealed elongation of the O-O bond of TBHP upon coordination.

  10. Motor Training Promotes Both Synaptic and Intrinsic Plasticity of Layer II/III Pyramidal Neurons in the Primary Motor Cortex

    PubMed Central

    Kida, Hiroyuki; Tsuda, Yasumasa; Ito, Nana; Yamamoto, Yui; Owada, Yuji; Kamiya, Yoshinori; Mitsushima, Dai

    2016-01-01

    Motor skill training induces structural plasticity at dendritic spines in the primary motor cortex (M1). To further analyze both synaptic and intrinsic plasticity in the layer II/III area of M1, we subjected rats to a rotor rod test and then prepared acute brain slices. Motor skill consistently improved within 2 days of training. Voltage clamp analysis showed significantly higher α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/N-methyl-d-aspartate (AMPA/NMDA) ratios and miniature EPSC amplitudes in 1-day trained rats compared with untrained rats, suggesting increased postsynaptic AMPA receptors in the early phase of motor learning. Compared with untrained controls, 2-days trained rats showed significantly higher miniature EPSC amplitude and frequency. Paired-pulse analysis further demonstrated lower rates in 2-days trained rats, suggesting increased presynaptic glutamate release during the late phase of learning. One-day trained rats showed decreased miniature IPSC frequency and increased paired-pulse analysis of evoked IPSC, suggesting a transient decrease in presynaptic γ-aminobutyric acid (GABA) release. Moreover, current clamp analysis revealed lower resting membrane potential, higher spike threshold, and deeper afterhyperpolarization in 1-day trained rats—while 2-days trained rats showed higher membrane potential, suggesting dynamic changes in intrinsic properties. Our present results indicate dynamic changes in glutamatergic, GABAergic, and intrinsic plasticity in M1 layer II/III neurons after the motor training. PMID:27193420

  11. Potential markers of oxidative stress in stroke.

    PubMed

    Cherubini, Antonio; Ruggiero, Carmelinda; Polidori, M Cristina; Mecocci, Patrizia

    2005-10-01

    Free radical production is increased in ischemic and hemorrhagic stroke, leading to oxidative stress that contributes to brain damage. The measurement of oxidative stress in stroke would be extremely important for a better understanding of its pathophysiology and for identifying subgroups of patients that might receive targeted therapeutic intervention. Since direct measurement of free radicals and oxidized molecules in the brain is difficult in humans, several biological substances have been investigated as potential peripheral markers. Among lipid peroxidation products, malondialdehyde, despite its relevant methodological limitations, is correlated with the size of ischemic stroke and clinical outcome, while F2-isoprostanes appear to be promising, but they have not been adequately evaluated. 8-Hydroxy-2-deoxyguanosine has been extensively investigated as markers of oxidative DNA damage but no study has been done in stroke patients. Also enzymatic and nonenzymatic antioxidants have been proposed as indirect markers. Among them ascorbic acid, alpha-tocopherol, uric acid, and superoxide dismutase are related to brain damage and clinical outcome. After a critical evaluation of the literature, we conclude that, while an ideal biomarker is not yet available, the balance between antioxidants and by-products of oxidative stress in the organism might be the best approach for the evaluation of oxidative stress in stroke patients.

  12. Tetrahydrocannabinol Induces Brain Mitochondrial Respiratory Chain Dysfunction and Increases Oxidative Stress: A Potential Mechanism Involved in Cannabis-Related Stroke

    PubMed Central

    Wolff, Valérie; Schlagowski, Anna-Isabel; Rouyer, Olivier; Charles, Anne-Laure; Singh, François; Auger, Cyril; Schini-Kerth, Valérie; Marescaux, Christian; Raul, Jean-Sébastien; Zoll, Joffrey; Geny, Bernard

    2015-01-01

    Cannabis has potential therapeutic use but tetrahydrocannabinol (THC), its main psychoactive component, appears as a risk factor for ischemic stroke in young adults. We therefore evaluate the effects of THC on brain mitochondrial function and oxidative stress, key factors involved in stroke. Maximal oxidative capacities Vmax (complexes I, III, and IV activities), Vsucc (complexes II, III, and IV activities), Vtmpd (complex IV activity), together with mitochondrial coupling (Vmax/V0), were determined in control conditions and after exposure to THC in isolated mitochondria extracted from rat brain, using differential centrifugations. Oxidative stress was also assessed through hydrogen peroxide (H2O2) production, measured with Amplex Red. THC significantly decreased Vmax (−71%; P < 0.0001), Vsucc (−65%; P < 0.0001), and Vtmpd (−3.5%; P < 0.001). Mitochondrial coupling (Vmax/V0) was also significantly decreased after THC exposure (1.8±0.2 versus 6.3±0.7; P < 0.001). Furthermore, THC significantly enhanced H2O2 production by cerebral mitochondria (+171%; P < 0.05) and mitochondrial free radical leak was increased from 0.01±0.01 to 0.10±0.01% (P < 0.001). Thus, THC increases oxidative stress and induces cerebral mitochondrial dysfunction. This mechanism may be involved in young cannabis users who develop ischemic stroke since THC might increase patient's vulnerability to stroke. PMID:25654095

  13. Tetrahydrocannabinol induces brain mitochondrial respiratory chain dysfunction and increases oxidative stress: a potential mechanism involved in cannabis-related stroke.

    PubMed

    Wolff, Valérie; Schlagowski, Anna-Isabel; Rouyer, Olivier; Charles, Anne-Laure; Singh, François; Auger, Cyril; Schini-Kerth, Valérie; Marescaux, Christian; Raul, Jean-Sébastien; Zoll, Joffrey; Geny, Bernard

    2015-01-01

    Cannabis has potential therapeutic use but tetrahydrocannabinol (THC), its main psychoactive component, appears as a risk factor for ischemic stroke in young adults. We therefore evaluate the effects of THC on brain mitochondrial function and oxidative stress, key factors involved in stroke. Maximal oxidative capacities V max (complexes I, III, and IV activities), V succ (complexes II, III, and IV activities), V tmpd (complex IV activity), together with mitochondrial coupling (V max/V 0), were determined in control conditions and after exposure to THC in isolated mitochondria extracted from rat brain, using differential centrifugations. Oxidative stress was also assessed through hydrogen peroxide (H2O2) production, measured with Amplex Red. THC significantly decreased V max (-71%; P < 0.0001), V succ (-65%; P < 0.0001), and V tmpd (-3.5%; P < 0.001). Mitochondrial coupling (V max/V 0) was also significantly decreased after THC exposure (1.8±0.2 versus 6.3±0.7; P < 0.001). Furthermore, THC significantly enhanced H2O2 production by cerebral mitochondria (+171%; P < 0.05) and mitochondrial free radical leak was increased from 0.01±0.01 to 0.10±0.01% (P < 0.001). Thus, THC increases oxidative stress and induces cerebral mitochondrial dysfunction. This mechanism may be involved in young cannabis users who develop ischemic stroke since THC might increase patient's vulnerability to stroke.

  14. Porphyrin-sensitized solar cells with cobalt (II/III)-based redox electrolyte exceed 12 percent efficiency.

    PubMed

    Yella, Aswani; Lee, Hsuan-Wei; Tsao, Hoi Nok; Yi, Chenyi; Chandiran, Aravind Kumar; Nazeeruddin, Md Khaja; Diau, Eric Wei-Guang; Yeh, Chen-Yu; Zakeeruddin, Shaik M; Grätzel, Michael

    2011-11-04

    The iodide/triiodide redox shuttle has limited the efficiencies accessible in dye-sensitized solar cells. Here, we report mesoscopic solar cells that incorporate a Co((II/III))tris(bipyridyl)-based redox electrolyte in conjunction with a custom synthesized donor-π-bridge-acceptor zinc porphyrin dye as sensitizer (designated YD2-o-C8). The specific molecular design of YD2-o-C8 greatly retards the rate of interfacial back electron transfer from the conduction band of the nanocrystalline titanium dioxide film to the oxidized cobalt mediator, which enables attainment of strikingly high photovoltages approaching 1 volt. Because the YD2-o-C8 porphyrin harvests sunlight across the visible spectrum, large photocurrents are generated. Cosensitization of YD2-o-C8 with another organic dye further enhances the performance of the device, leading to a measured power conversion efficiency of 12.3% under simulated air mass 1.5 global sunlight.

  15. Genetic improvement of U.S. soybean in Maturity Groups II, III, and IV

    USDA-ARS?s Scientific Manuscript database

    Soybean [Glycine max (L.) Merr.] improvement via plant breeding has been critical for the success of the crop. The objective of this study was to quantify genetic change in yield and other traits that occurred over the past 80 years of North American soybean breeding in maturity groups (MGs) II, III...

  16. Renal Tubular Mitochondrial Abnormalities in Complex II/III Respiratory Chain Deficiency.

    PubMed

    France, Joel; Ashoor, Isa; Craver, Randall

    2017-06-01

    Defects in the respiratory chain may present with a wide spectrum of clinical signs and symptoms. In this "Images in Pathology" discussion we correlate the clinical, histologic, and ultrastructural findings in a 12-year-old male with a complex II/III respiratory chain deficiency and kidney dysfunction.

  17. CHEMICAL INTERACTIONS OF ARSENATE, ARSENITE, PHOSPHATE, AND SILICATE WITH IRON (II, III) HYDROXYCARBONATE GREEN RUST

    EPA Science Inventory

    Granular zerovalent iron has been proposed to be used as a medium in permeable reactive barriers (PRBs) to remove arsenic from contaminated groundwater. Iron(II, III) hydroxycarbonate green rust (carbonate green rust, or CGR) is a major corrosion product of zerovalent iron under ...

  18. CHEMICAL INTERACTIONS OF ARSENATE, ARSENITE, PHOSPHATE, AND SILICATE WITH IRON (II,III) HYDROXYCARBONATE GREEN RUST

    EPA Science Inventory

    Granular zerovalent iron has been proposed to be used as a medium in permeable reactive barriers (PRBs) to remove arsenic from contaminated groundwater. Iron(II, III) hydroxycarbonate green rust (carbonate green rust, or CGR) is a major corrosion product of zerovalent iron under ...

  19. CHEMICAL INTERACTIONS OF ARSENATE, ARSENITE, PHOSPHATE, AND SILICATE WITH IRON (II,III) HYDROXYCARBONATE GREEN RUST

    EPA Science Inventory

    Granular zerovalent iron has been proposed to be used as a medium in permeable reactive barriers (PRBs) to remove arsenic from contaminated groundwater. Iron(II, III) hydroxycarbonate green rust (carbonate green rust, or CGR) is a major corrosion product of zerovalent iron under ...

  20. CHEMICAL INTERACTIONS OF ARSENATE, ARSENITE, PHOSPHATE, AND SILICATE WITH IRON (II, III) HYDROXYCARBONATE GREEN RUST

    EPA Science Inventory

    Granular zerovalent iron has been proposed to be used as a medium in permeable reactive barriers (PRBs) to remove arsenic from contaminated groundwater. Iron(II, III) hydroxycarbonate green rust (carbonate green rust, or CGR) is a major corrosion product of zerovalent iron under ...

  1. Oxidation Potentials in Iron and Steel Making

    NASA Astrophysics Data System (ADS)

    Matousek, J. W.

    2013-11-01

    The state of oxidation of a pyrometallurgical process given by the partial pressure of oxygen and the temperature (the oxidation potential) is one of the important properties monitored and controlled in the smelting and refining of iron and the nonferrous metals. Solid electrolyte sensors based on ZrO2 and a reference electrode such as Cr/Cr2O3 to measure the oxygen pressure found early application in the steel industry, followed soon after in copper, nickel, lead, and zinc smelting. Similar devices are installed in automobile postcombustion/exhaust trains as part of emission control systems. The current discussion reviews this technology as applied in the primary steps of iron and steel making and refining.

  2. 40 CFR 147.650 - State-administrative program-Class I, II, III, IV, and V wells.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CONTROL PROGRAMS Idaho § 147.650 State-administrative program—Class I, II, III, IV, and V wells. The UIC program for Class I, II, III, IV, and V wells in the State of Idaho, other than those on Indian lands, is the program administered by the Idaho Department of Water Resources, approved by EPA pursuant to...

  3. 40 CFR 147.650 - State-administrative program-Class I, II, III, IV, and V wells.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CONTROL PROGRAMS Idaho § 147.650 State-administrative program—Class I, II, III, IV, and V wells. The UIC program for Class I, II, III, IV, and V wells in the State of Idaho, other than those on Indian lands, is the program administered by the Idaho Department of Water Resources, approved by EPA pursuant to...

  4. 40 CFR 147.650 - State-administrative program-Class I, II, III, IV, and V wells.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... CONTROL PROGRAMS Idaho § 147.650 State-administrative program—Class I, II, III, IV, and V wells. The UIC program for Class I, II, III, IV, and V wells in the State of Idaho, other than those on Indian lands, is the program administered by the Idaho Department of Water Resources, approved by EPA pursuant to...

  5. Play the winner for phase II/III clinical trials.

    PubMed

    Yao, Q; Wei, L J

    In comparing two treatments under a typical sequential clinical trial setting, a 50-50 randomization design generates reliable data for making efficient inferences about the treatment difference for the benefit of patients in the general population. However, if the treatment difference is large and the endpoint of the study is potentially fatal, it does not seem appropriate to sacrifice a large number of study patients who are assigned to the inferior arm. An adaptive design is a data-dependent treatment allocation rule that sequentially uses accumulating information about the treatment difference during the trial to modify the allocation rule for new study patients. In this article, we utilize real trials from AIDS and cancer to illustrate the advantage of using adaptive designs. Specifically we show that, with adaptive designs, the loss of power for testing the equality of two treatments is negligible. Moreover, the study patients do not have to pay a handsome price for the benefit of future patients. We also propose multi-stage adaptive rules to relax the administrative burden of implementing the study and to handle continuous response variables, such as the failure time in survival analysis.

  6. Potential role of bicarbonate during pyrite oxidation

    SciTech Connect

    Evangelou, V.P.; Holt, A.; Seta, A.K.

    1998-07-15

    The need to prevent the development of acid mine drainage (AMD) by oxidation of pyrite has triggered numerous investigations into the mechanisms of its oxidation. According to Frontier molecular orbital (FMO) theory, the surface-exposed sulfur atom of pyrite possesses an unshared electron pair which produces a slightly negatively charged pyrite surface that can attract cations such as Fe{sup 2+}. Because of surface electroneutrality and pH considerations, however, the pyrite surface Fe{sup 2+} coordinates OH. The authors proposed that this surface Fe{sup 2+} OH when in the presence of CO{sub 2} is converted to {minus}FeCO{sub 3} or {minus}FeHCO{sub 3}, depending on pH. In this study, using Fourier transform infrared spectroscopy (FT-IR) they demonstrated that such complexes form on the surface of pyrite and continue to persist even after a significant fraction of the surface Fe{sup 2+} was oxidized to Fe{sup 3+}. FT-IR spectra also showed the presence of two carbonyl absorption bands (1,682 and 1,653 cm{sup {minus}1}) on the surface of pyrite upon exposure to CO{sub 2} which suggested that pyrite surface carbon complexes existed in two different surface chemical environments, pointing out two potential mechanisms of pyrite surface-CO{sub 2} interactions. One potential mechanism involved formation of a pyrite surface-Fe(II)HCO{sub 3} complex, whereas a second potential mechanism involved formation of a pyrite surface-carboxylic acid group complex [{minus}Fe(II)SSCOOFe-(II)].

  7. Transparent Conducting Oxides as Potential Thermoelectrics

    NASA Astrophysics Data System (ADS)

    Mason, Thomas

    2013-03-01

    Transparent conducting oxides (TCOs) in their less-doped semiconducting states have potential as thermoelectric oxides or TEOs. They are attractive as TEOs owing to: 1) their good thermochemical stability, 2) their n-type character (to complement existing p-type TEOs), and 3) their high electronic mobilities. The numerator of the TE figure of merit (Z), also known as the ``power factor'' (PF), is the product of the electronic conductivity and the square of the Seebeck coefficient. An experimental procedure named after its developer, ``Jonker'' analysis plots Seebeck coefficient vs. the natural logarithm of the electronic conductivity. Data for bulk ceramic specimens just prior to the onset of degeneracy tend to fall on a line of slope, k/e (k =Boltzmann constant, e =charge of the electron). From this line, the doping composition corresponding to the highest power factor can be determined and the PF optimized, based upon data from a few carefully chosen compositions. Subsequently, following a procedure originally derived by Ioffe, the zero-thermopower intercept of these Jonker lines can be directly related to the maximum achievable power factor for a given TEO. So-called ``Ioffe'' plots allow for meaningful comparisons between candidate TEO materials, and also indicate the minimum thermal conductivity required to achieve a target ZT value at the temperature of measurement. Results for TCO-based TEOs will be discussed for both simple and compound (including layered) materials. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences as part of an Energy Frontier Research Center under grant no. DE-SC0001059.

  8. Equatorially connected diruthenium(II,III) units toward paramagnetic supramolecular structures with singular magnetic properties.

    PubMed

    Barral, M Carmen; Gallo, Teresa; Herrero, Santiago; Jiménez-Aparicio, Reyes; Torres, M Rosario; Urbanos, Francisco A

    2006-05-01

    The reaction of Ru2Cl(O2CMe)(DPhF)3 (DPhF = N,N'-diphenylformamidinate) with mono- and polycarboxylic acids gives a clean substitution of the acetate ligand, leading to the formation of complexes Ru2Cl(O2CC6H5)(DPhF)3 (1), Ru2Cl(O2CC6H4-p-CN)(DPhF)3 (2), [Ru2Cl(DPhF)3(H2O)]2(O2C)2 (3), [Ru2Cl(DPhF)3]2[C6H4-p-(CO2)2] (4), and [Ru2Cl(DPhF)3]3[C6H3-1,3,5-(CO2)3] (5). The preparation of [Ru2(NCS)(DPhF)3]3[C6H3-1,3,5-(CO2)3] (6) and {[Ru2(DPhF)3(H2O)]3[C6H3-1,3,5-(CO2)3]}(SO3CF3)3 (7) from 5 is also described. All complexes are characterized by elemental analysis, IR and electronic spectroscopy, mass spectrometry, cyclic voltammetry, and variable-temperature magnetic measurements. The crystal structure determinations of complexes 2.0.5THF and 3.THF.4H2O (THF = tetrahydrofuran) are reported. The reactions carried out demonstrate the high chemical stability of the fragment [Ru2(DPhF)3]2+, which is preserved in all tested experimental conditions. The stability of this fragment is also corroborated by the mass spectra. Electrochemical measurements reveal in all complexes one redox process due to the equilibrium Ru2(5+) <--> Ru2(6+). In the polynuclear complex 7, some additional oxidation processes are also observed that have been ascribed to the presence of two types of dimetallic units rather than two consecutive reversible oxidations. The magnetic behavior toward temperature for complexes 1-7 from 300 to 2 K is analyzed. Complexes 1-7 show low values of antiferromagnetic coupling in accordance with the molecular nature in 1 and 2 and the absence of important antiferromagnetic interaction through the carboxylate bridging ligands in 3-7, respectively. In addition, the magnetic properties of complex 7 do not correspond to any magnetic behavior described for diruthenium(II,III) complexes. The experimental data of compound 7 are simulated considering a physical mixture of S = 1/2 and 3/2 spin states. This magnetic study demonstrates the high sensitivity of the electronic

  9. Novel graphite salts of high oxidizing potential

    SciTech Connect

    McCarron, E.M. III

    1980-08-01

    The intercalation of graphite by the third-transition-series metal hexafluorides has yielded the graphite salts, C/sub 8//sup +/OsF/sub 6//sup -/, C/sub 8//sup +/IrF/sub 6//sup -/ and C/sub 12//sup 2 +/PtF/sub 6//sup 2 -/. The fluoroplatinate salt represents the highest electron withdrawal from the graphite network yet achieved. Analogues to the Os and Ir salts have been obtained both by fluorination of Group V pentaflouride intercalates, C/sub 8/MF/sub 5/ (M = As, Sb), and by the interaction of the dioxygenyl salts with graphite (8C + O/sub 2/MF/sub 6/ ..-->.. C/sub 8/MF/sub 6/ + O/sub 2/+). Non-intercalating binary fluorides have been observed to intercalate in the presence of a fluorine-rich environment (e.g., 8C + PF/sub 5/ + 1/2 F/sub 2/ ..-->.. C/sub 8/PF/sub 6/). GeF/sub 4/, which also does not spontaneously intercalate graphite, has been observed to interact with graphite in the presence of 2 atmospheres of fluorine overpressure to give the fluoroplatinate salt analogue, C/sub 12//sup 2 +/GeF/sub 6//sup 2 -/. This material is in equilibrium with the pentafluorogermanate at ordinary pressures and temperatures. C/sub 12//sup 2 +/GeF/sub 6//sup 2 -/ ..-->.. C/sub 12//sup +/GeF/sub 5//sup -/ + 1/2 F/sub 2/. C/sub 12/GeF/sub 6/ must have an oxidizing potential close to that of fluorine itself. The graphite fluorometallate salts are both electronic and ionic (F/sup -/) conductors. For the C/sub 8//sup +/MF/sub 6//sup -/ salts, a maximum electronic conductivity an order of magnitude greater than the parent graphite has been observed for stage two. The high oxidizing potential, coupled with the fluoride ion transport capability of the graphite salts, has been exploited in the construction of solid-state galvanic cells. These cells use the graphite fluorometallate salts as electrode materials in combination with a superionic fluoride-ion-conducting solid electrolyte.

  10. Oxidation of Inconel alloy MA754 at low oxidation potential

    SciTech Connect

    Braski, D.N.; Goodell, P.D.; Cathcart, J.V.; Kane, R.H.

    1983-01-01

    It has been known for some time that the addition of small oxide particles to an 80 Ni-20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance was studied. Initial experiments were performed using inconel alloy MA754, which is nominally: 78 Ni, 20 Cr, 0.05 C, 0.3 Al, 0.5 Ti, 1.0 Fe, and 0.6 Y/sub 2/O/sub 3/ (wt %). Small disks (3 mm diam x 0.38 mm thick) were cut from MA754 plate stock and prepared with two different surface conditions. The first was prepared by mechanically polishing one side of a disk through 0.5 ..mu..m diamond on a syntron polisher while the second used an additional sulfuric acid-methanol electropolishing treatment to remove the cold-worked surface layer. Disks having both surface treatments were oxidized in a radiantly heated furnace for 30 s at 1000/sup 0/C. Three different environments were investigated: hydrogen with nominal dew points of 0/sup 0/C, -25/sup 0/C, and -55/sup 0/C. The oxide particles and films were examined in TEM by using extraction replicas (carbon) and by backpolishing to the oxide/metal interface. The particles were analyzed by EDS and SAD. Preliminary results are given.

  11. Esophagus or stomach? The seventh TNM classification for Siewert type II/III junctional adenocarcinoma.

    PubMed

    Hasegawa, Shinichi; Yoshikawa, Takaki; Aoyama, Toru; Hayashi, Tsutomu; Yamada, Takanobu; Tsuchida, Kazuhito; Cho, Haruhiko; Oshima, Takashi; Yukawa, Norio; Rino, Yasushi; Masuda, Munetaka; Tsuburaya, Akira

    2013-03-01

    The aim of this study is to clarify whether TNM-EC or TNM-GC is better for classifying patients with AEG types II/III. The patients who had AEG types II/III and received D1 or more radical lymphadenectomy were selected. The patients were staged both by seventh edition of TNM-EC and TNM-GC. The distribution of the patients, the hazard ratio (HR) of each stage, and the separation of the survival were compared. A total of 163 patients were enrolled in this study. TNM-EC and TNM-GC classified 25 (20 and 5) and 32 (20 and 12) patients to stage I (IA and IB), 15 (4 and 11), and 33 (11 and 22) to stage II (IIA and IIB), 88 (24, 3, and 61) and 63 (14, 26, and 23) to stage III (IIIA, IIIB, and IIIC), and 35 and 35 to stage IV, respectively. The distribution of the patients was substantially deviated to stage IIIC in TNM-EC but was almost even in TNM-GC. A stepwise increase of HR was observed in TNM-GC, but not in TNM-EC. The survival curves between stages II and III were significantly separated in TNM-GC (P = 0.019), but not in TNM-EC (P = 0.204). The 5-year survival rates of stages IIIA, IIIB, and IIIC were 69.0, 100, and 38.9% in TNM-EC and were 52.0, 43.4, and 33.9% in TNM-GC, respectively. TNM-GC is better for classifying patients with AEG types II/III than TNM-EC is. These results could impact the next TNM revision for AEG.

  12. Role of Natural Organic Matter in Regulating the Partitioning of Fe(II, III) in Seawater

    NASA Astrophysics Data System (ADS)

    Guo, L.; Chen, M.; Roberts, K.; Santschi, P. H.

    2008-12-01

    Iron (Fe) is an essential micronutrient and plays an important role in controlling ocean productivity and carbon cycling. Fe has been shown to be mostly complexed with dissolved organic matter in seawater. However, the interaction of Fe with natural organic matter and how the quality and quantity of organic matter affect the chemical speciation of Fe in seawater remain poorly understood. Controlled laboratory experiments have been conducted to examine the partitioning of Fe(II, III) between dissolved, colloidal and particulate phases using radiotracers, model organic compounds, and ultrafiltration. In natural seawater, Fe is mostly partitioned in the colloidal and particulate phases, resulting in a logKd value of 7.3 and a logKc of 6.1, respectively. On average, about 25% of dissolved Fe-55 was found in the <1 kDa fraction, 56% in the 1-10 kDa small colloidal fraction, 11% in the 10-100 kDa medium colloidal fraction, and 8% in the large colloidal fraction (100 kDa-0.4 μm). In experimental treatments with extracellular polysaccharides, the partitioning of Fe(II, III) changed from mostly in the colloidal fraction to mostly in the <1 kDa truly dissolved fraction, with on average 67% in the <1 kDa, 13% in the 1-10 kDa, 4% in the 10-100 kDa, and 6% in the 100 kDa-0.4 μm fraction. The increase in Fe(II, III) solubility in the presence of extracellular polysaccharides is hypothesized to be the result of Fe reduction from Fe(III), a more particle-reactive form, to Fe(II), a more soluble form, during its interactions with natural organic matter in seawater. This experimental result has important implications for the biogeochemical cycling of Fe(II, III) and other redox sensitive trace elements in the ocean. While the complexation of Fe with DOM could depress the bioavailability of Fe in seawater, the resultant Fe reduction may significantly enhance its solubility and bioavailability to marine organisms.

  13. Voluntary exercise partially reverses neonatal alcohol-induced deficits in mPFC layer II/III dendritic morphology of male adolescent rats.

    PubMed

    Hamilton, G F; Criss, K J; Klintsova, A Y

    2015-08-01

    Developmental alcohol exposure in humans can produce a wide range of deficits collectively referred to as fetal alcohol spectrum disorders (FASD). FASD-related impairments in executive functioning later in life suggest long-term damage to the prefrontal cortex (PFC). In rodent neonates, moderate to high levels of alcohol exposure decreased frontal lobe brain size and altered medial PFC pyramidal neuron dendritic morphology. Previous research in our lab demonstrated that neonatal alcohol exposure decreased basilar dendritic complexity but did not affect spine density in Layer II/III pyramidal neurons in 26- to 30-day-old rats. The current study adds to the literature by evaluating the effect of neonatal alcohol exposure on mPFC Layer II/III basilar dendritic morphology in adolescent male rats. Additionally, it examines the potential for voluntary exercise to mitigate alcohol-induced deficits on mPFC dendritic complexity. An animal model of binge drinking during the third trimester of pregnancy was used. Rats were intubated with alcohol (alcohol-exposed, AE; 5.25 g kg(-1) day(-1)) on postnatal days (PD) 4-9; two control groups were included (suckle control and sham-intubated). Rats were anesthetized and perfused with heparinized saline solution on PD 42, and brains were processed for Golgi-Cox staining. Developmental alcohol exposure decreased spine density and dendritic complexity of basilar dendrites of Layer II/III neurons in the medial PFC (mPFC) compared to dendrites of control animals. Voluntary exercise increased spine density and dendritic length in AE animals resulting in elimination of the differences between AE and SH rats. Thus, voluntary exercise during early adolescence selectively rescued alcohol-induced morphological deficits in the mPFC.

  14. Potential Modulation of Sirtuins by Oxidative Stress

    PubMed Central

    Santos, Leonardo; Escande, Carlos; Denicola, Ana

    2016-01-01

    Sirtuins are a conserved family of NAD-dependent protein deacylases. Initially proposed as histone deacetylases, it is now known that they act on a variety of proteins including transcription factors and metabolic enzymes, having a key role in the regulation of cellular homeostasis. Seven isoforms are identified in mammals (SIRT1–7), all of them sharing a conserved catalytic core and showing differential subcellular localization and activities. Oxidative stress can affect the activity of sirtuins at different levels: expression, posttranslational modifications, protein-protein interactions, and NAD levels. Mild oxidative stress induces the expression of sirtuins as a compensatory mechanism, while harsh or prolonged oxidant conditions result in dysfunctional modified sirtuins more prone to degradation by the proteasome. Oxidative posttranslational modifications have been identified in vitro and in vivo, in particular cysteine oxidation and tyrosine nitration. In addition, oxidative stress can alter the interaction with other proteins, like SIRT1 with its protein inhibitor DBC1 resulting in a net increase of deacetylase activity. In the same way, manipulation of cellular NAD levels by pharmacological inhibition of other NAD-consuming enzymes results in activation of SIRT1 and protection against obesity-related pathologies. Nevertheless, further research is needed to establish the molecular mechanisms of redox regulation of sirtuins to further design adequate pharmacological interventions. PMID:26788256

  15. Potential Modulation of Sirtuins by Oxidative Stress.

    PubMed

    Santos, Leonardo; Escande, Carlos; Denicola, Ana

    2016-01-01

    Sirtuins are a conserved family of NAD-dependent protein deacylases. Initially proposed as histone deacetylases, it is now known that they act on a variety of proteins including transcription factors and metabolic enzymes, having a key role in the regulation of cellular homeostasis. Seven isoforms are identified in mammals (SIRT1-7), all of them sharing a conserved catalytic core and showing differential subcellular localization and activities. Oxidative stress can affect the activity of sirtuins at different levels: expression, posttranslational modifications, protein-protein interactions, and NAD levels. Mild oxidative stress induces the expression of sirtuins as a compensatory mechanism, while harsh or prolonged oxidant conditions result in dysfunctional modified sirtuins more prone to degradation by the proteasome. Oxidative posttranslational modifications have been identified in vitro and in vivo, in particular cysteine oxidation and tyrosine nitration. In addition, oxidative stress can alter the interaction with other proteins, like SIRT1 with its protein inhibitor DBC1 resulting in a net increase of deacetylase activity. In the same way, manipulation of cellular NAD levels by pharmacological inhibition of other NAD-consuming enzymes results in activation of SIRT1 and protection against obesity-related pathologies. Nevertheless, further research is needed to establish the molecular mechanisms of redox regulation of sirtuins to further design adequate pharmacological interventions.

  16. A modified varying-stage adaptive phase II/III clinical trial design.

    PubMed

    Dong, Gaohong; Vandemeulebroecke, Marc

    2016-07-01

    Conventionally, adaptive phase II/III clinical trials are carried out with a strict two-stage design. Recently, a varying-stage adaptive phase II/III clinical trial design has been developed. In this design, following the first stage, an intermediate stage can be adaptively added to obtain more data, so that a more informative decision can be made. Therefore, the number of further investigational stages is determined based upon data accumulated to the interim analysis. This design considers two plausible study endpoints, with one of them initially designated as the primary endpoint. Based on interim results, another endpoint can be switched as the primary endpoint. However, in many therapeutic areas, the primary study endpoint is well established. Therefore, we modify this design to consider one study endpoint only so that it may be more readily applicable in real clinical trial designs. Our simulations show that, the same as the original design, this modified design controls the Type I error rate, and the design parameters such as the threshold probability for the two-stage setting and the alpha allocation ratio in the two-stage setting versus the three-stage setting have a great impact on the design characteristics. However, this modified design requires a larger sample size for the initial stage, and the probability of futility becomes much higher when the threshold probability for the two-stage setting gets smaller. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Aluminium substitution in iron(II III)-layered double hydroxides: Formation and cationic order

    NASA Astrophysics Data System (ADS)

    Ruby, Christian; Abdelmoula, Mustapha; Aissa, Rabha; Medjahdi, Ghouti; Brunelli, Michela; François, Michel

    2008-09-01

    The formation and the modifications of the structural properties of an aluminium-substituted iron(II-III)-layered double hydroxide (LDH) of formula Fe4IIFe(2-6y)IIIAl6yIII (OH) 12 SO 4, 8H 2O are followed by pH titration curves, Mössbauer spectroscopy and high-resolution X-ray powder diffraction using synchrotron radiation. Rietveld refinements allow to build a structural model for hydroxysulphate green rust, GR(SO 42-), i.e. y=0, in which a bilayer of sulphate anions points to the Fe 3+ species. A cationic order is proposed to occur in both GR(SO 42-) and aluminium-substituted hydroxysulphate green rust when y<0.08. Variation of the cell parameters and a sharp decrease in average crystal size and anisotropy are detected for an aluminium content as low as y=0.01. The formation of Al-GR(SO 42-) is preceded by the successive precipitation of Fe III and Al III (oxy)hydroxides. Adsorption of more soluble Al III species onto the initially formed ferric oxyhydroxide may be responsible for this slowdown of crystal growth. Therefore, the insertion of low aluminium amount ( y˜0.01) could be an interesting way for increasing the surface reactivity of iron(II-III) LDH that maintains constant the quantity of the reactive Fe II species of the material.

  18. Multicenter prospective validation of the Baveno IV and Baveno II/III criteria in cirrhosis patients with variceal bleeding.

    PubMed

    Thabut, Dominique; Rudler, Marika; Dib, Nina; Carbonell, Nicolas; Mathurin, Philippe; Saliba, Faouzi; Mallet, Alain; Massard, Julien; Bernard-Chabert, Brigitte; Oberti, Frederic; Cales, Paul; Golmard, Jean-Louis; Bureau, Christophe

    2015-03-01

    The criteria for defining failure to control bleeding in cirrhosis patients were introduced at the Baveno II/III meetings and were widely used as endpoints in clinical trials. Because they lacked specificity, the Baveno IV criteria were proposed in 2005 and slightly modified in 2010 (Baveno V). These criteria included a new index for patients undergoing transfusion, called adjusted-blood-requirement-index (ABRI=number of blood units/(final-initial hematocrit+0.01)), with a cutoff value of 0.75. In this multicenter prospective study, we sought to 1) validate the Baveno IV/V criteria; 2) compare them to the Baveno II/III criteria; 3) assess ABRI performance using a standardized calculation. The key inclusion criteria were: 1) variceal bleeding; 2) cirrhosis; 3) no need to modify the transfusion policy. The patients were classified according to the Baveno IV, V, and II/III criteria. The gold standard for failure during a 5-day period was the clinical judgment of three independent experts, blinded to the Baveno assessments. A total of 249 patients were included. The experts' agreement in clinical judgment of the failure was 80%. Failure occurred in 20.5% of patients; the c-statistics were 0.72 versus 0.64 and 0.65 for Baveno IV versus Baveno II/III and Baveno V criteria (P=0.001 for both). ABRI did not improve the diagnostic performance of the Baveno IV criteria. The Baveno IV, but not Baveno II/III, criteria independently predicted survival. The Baveno IV criteria demonstrated a higher accuracy than the Baveno II/III and Baveno V criteria for assessing failure to control bleeding and predicted survival independently. Together, our results show that ABRI is not a useful metric, and the Baveno IV criteria should replace the Baveno II/III criteria. © 2014 by the American Association for the Study of Liver Diseases.

  19. OXIDATION-REDUCTION POTENTIAL MEASUREMENTS OF IMPORTANT OXIDANTS IN DRINKING WATER

    EPA Science Inventory

    Oxidation-reduction (redox) reactions are important in drinking water treatment and distribution. Oxidation-reduction potential (ORP) measurements of water reflect the tendency of major constituents in the water to accept or lose electrons. Although ORP measurements are valuable...

  20. OXIDATION-REDUCTION POTENTIAL MEASUREMENTS OF IMPORTANT OXIDANTS IN DRINKING WATER

    EPA Science Inventory

    Oxidation-reduction (redox) reactions are important in drinking water treatment and distribution. Oxidation-reduction potential (ORP) measurements of water reflect the tendency of major constituents in the water to accept or lose electrons. Although ORP measurements are valuable...

  1. GLASSES CONTAINING IRON (II III) OXIDES FOR IMMOBILIZATION OF RADIOACTIVE TECHNETIUM

    SciTech Connect

    KRUGER AA; HEO J; XU K; CHOI JK; HRMA PR; UM W

    2011-11-07

    Technetium-99 (Tc-99) has posed serious environmental threats as US Department of Energy's high-level waste. This work reports the vitrification of Re, as surrogate for Tc-99, by iron-borosilicate and iron-phosphate glasses, respectively. Iron-phosphate glasses can dissolve Re as high as {approx} 1.2 wt. %, which can become candidate waste forms for Tc-99 disposal, while borosilicate glasses can retain less than 0.1 wt. % of Re due to high melting temperature and long melting duration. Vitrification of Re as Tc-99's mimic was investigated using iron-borosilicate and iron-phosphate glasses. The retention of Re in borosilicate glasses was less than 0.1 wt. % and more than 99 wt. % of Re were volatilized due to high melting temperature and long melting duration. Because the retention of Re in iron-phosphate glasses is as high as 1.2 wt. % and the volatilization is reduced down to {approx}50 wt. %, iron-phosphate glasses can be one of the glass waste form candidates for Tc (or Re) disposal. The investigations of chemical durability and leaching test of iron-phosphate glasses containing Re are now underway to test the performance of the waste form.

  2. The impact of local control in the treatment of type II/III pleuropulmonary blastoma. Experience of the Cooperative Weichteilsarkom Studiengruppe (CWS).

    PubMed

    Sparber-Sauer, Monika; Seitz, Guido; Kirsch, Sylvia; Vokuhl, Christian; Leuschner, Ivo; Dantonello, Tobias M; Scheer, Monika; von Kalle, Thekla; Ljungman, Gustaf; Bielack, Stefan S; Klingebiel, Thomas; Fuchs, Joerg; Koscielniak, Ewa

    2017-02-01

    This study aims at examining the potential survival benefits of primary versus secondary surgery in the management of children diagnosed with pleuropulmonary blastoma (PPB) type II/III. Disease characteristics, treatment, and survival of 29 children with localized PPB type II/III, treated in six prospective Cooperative Weichteilsarkom Studiengruppe (CWS) trials, were reviewed retrospectively. Five year event free survival (EFS) and overall survival (OS) of children treated according to CWS protocols was 72%. Patients with tumors ≤10 cm had a 5 year OS of 91% versus 57% in patients with tumors >10 cm (P = 0.025). Five year OS of patients with macroscopically incomplete upfront resections was 44% as opposed to 68% in patients with delayed/secondary microscopically or macroscopically complete resection after an initial biopsy (P = 0.476). Ten patients died of disease, one patient died of second malignancy. Tumor size and complete tumor resection at any time were significant prognostic factors (P = 0.025/0.003) for EFS. EFS for microscopically complete, microscopically incomplete, and macroscopically incomplete resection at any time was 91%, 90%, and 25%, respectively (P = 0.01). Primary or secondary microscopically/macroscopically complete tumor resections in combination with chemotherapy correlates with long term survival in children with PPB. J. Surg. Oncol. 2017;115:164-172. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  3. A varying-stage adaptive phase II/III clinical trial design.

    PubMed

    Dong, Gaohong

    2014-04-15

    Currently, adaptive phase II/III clinical trials are typically carried out with a strict two-stage design. The first stage is a learning stage called phase II, and the second stage is a confirmatory stage called phase III. Following phase II analysis, inefficacious or harmful dose arms are dropped, then one or two promising dose arms are selected for the second stage. However, there are often situations in which researchers are in dilemma to make 'go or no-go' decision and/or to select 'best' dose arm(s), as data from the first stage may not provide sufficient information for their decision making. In this case, it is challenging to follow a strict two-stage plan. Therefore, we propose a varying-stage adaptive phase II/III clinical trial design, in which we consider whether there is a need to have an intermediate stage to obtain more data, so that a more informative decision could be made. Hence, the number of further investigational stages in our design is determined on the basis of data accumulated to the interim analysis. With respect to adaptations, we consider dropping dose arm(s), switching another plausible endpoint as the primary study endpoint, re-estimating sample size, and early stopping for futility. We use an adaptive combination test to perform final analyses. By applying closed testing procedure, we control family-wise type I error rate at the nominal level of α in the strong sense. We delineate other essential design considerations including the threshold parameters and the proportion of alpha allocated in the two-stage versus three-stage setting.

  4. Extraction radiopolarography for determining the oxidation potentials of transplutonium elements

    SciTech Connect

    Kosyakov, V.N.; Yakovlev, N.G.; Vlasov, M.M.

    1987-03-01

    A method is described for determining the oxidation potentials for valency transitions in transplutonium elements (TPE), which is usable when the element is present in trace amounts. This is based on electrochemical oxidation or reduction of the TPE in combination with a solvent-extraction method of determining the concentration ratio for the oxidized and reduced forms. The method is applicable to determining the potential of almost any reversible reaction if the solvent-extraction parameters for the oxidized and reduced forms differ substantially, while the potential (with allowance for the extraction system) lies in a region accessible to electrochemical oxidation or reduction. Two forms of use are considered: with liquid extraction and with extraction chromatography. The method is demonstrated on the Bk(IV)/Bk(III) transition with di-2-ethylhexylphosphoric acid as extraction agent.

  5. Sequential extraction method for determination of Fe(II/III) and U(IV/VI) in suspensions of iron-bearing phyllosilicates and uranium.

    PubMed

    Luan, Fubo; Burgos, William D

    2012-11-06

    Iron-bearing phyllosilicates strongly influence the redox state and mobility of uranium because of their limited hydraulic conductivity, high specific surface area, and redox reactivity. Standard extraction procedures cannot be accurately applied for the determination of clay-Fe(II/III) and U(IV/VI) in clay mineral-U suspensions such that advanced spectroscopic techniques are required. Instead, we developed and validated a sequential extraction method for determination of clay-Fe(II/III) and U(IV/VI) in clay-U suspensions. In our so-called "H(3)PO(4)-HF-H(2)SO(4) sequential extraction" method, H(3)PO(4)-H(2)SO(4) is used first to solubilize and remove U, and the remaining clay pellet is subject to HF-H(2)SO(4) digestion. Physical separation of U and clay eliminates valence cycling between U(IV/VI) and clay-Fe(II/III) that otherwise occurred in the extraction solutions and caused analytical discrepancies. We further developed an "automated anoxic KPA" method to measure soluble U(VI) and total U (calculate U(IV) by difference) and modified the conventional HF-H(2)SO(4) digestion method to eliminate a series of time-consuming weighing steps. We measured the kinetics of uraninite oxidation by nontronite using this sequential extraction method and anoxic KPA method and measured a stoichiometric ratio of 2.19 ± 0.05 mol clay-Fe(II) produced per mol U(VI) produced (theoretical value of 2.0). We found that we were able to recover 98.0-98.5% of the clay Fe and 98.1-98.5% of the U through the sequential extractions. Compared to the theoretical stoichiometric ratio of 2.0, the parallel extractions of 0.5 M HCl for clay-Fe(II) and 1 M NaHCO(3) for U(VI) leached two-times more Fe(II) than U(VI). The parallel extractions of HF-H(2)SO(4) for clay Fe(II) and 1 M NaHCO(3) for U(VI) leached six-times more Fe(II) than U(VI).

  6. 40 CFR 147.2650 - State-administered program-Class I, II, III, IV, and V wells.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CONTROL PROGRAMS Puerto Rico § 147.2650 State-administered program—Class I, II, III, IV, and V wells. The Underground Injection Control Program for all classes of wells in the Commonwealth of Puerto Rico, other than those on Indian lands, is the program administered by Puerto Rico's Environmental Quality Board (EQB...

  7. 40 CFR 147.2650 - State-administered program-Class I, II, III, IV, and V wells.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CONTROL PROGRAMS Puerto Rico § 147.2650 State-administered program—Class I, II, III, IV, and V wells. The Underground Injection Control Program for all classes of wells in the Commonwealth of Puerto Rico, other than those on Indian lands, is the program administered by Puerto Rico's Environmental Quality Board (EQB...

  8. 40 CFR 147.2650 - State-administered program-Class I, II, III, IV, and V wells.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... CONTROL PROGRAMS Puerto Rico § 147.2650 State-administered program—Class I, II, III, IV, and V wells. The Underground Injection Control Program for all classes of wells in the Commonwealth of Puerto Rico, other than those on Indian lands, is the program administered by Puerto Rico's Environmental Quality Board (EQB...

  9. 40 CFR 147.2650 - State-administered program-Class I, II, III, IV, and V wells.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... CONTROL PROGRAMS Puerto Rico § 147.2650 State-administered program—Class I, II, III, IV, and V wells. The Underground Injection Control Program for all classes of wells in the Commonwealth of Puerto Rico, other than those on Indian lands, is the program administered by Puerto Rico's Environmental Quality Board (EQB...

  10. ROLE OF IRON (II, III) HYDROXYCARBONATE GREEN RUST IN ARSENIC REMEDIATION USING ZEROVALENT IRON IN COLUMN TESTS

    EPA Science Inventory

    We examined corrosion products of zerovalent iron (Peerless iron) that was used in three column tests for removing arsenic under dynamic flow conditions with and without added phosphate and silicate. Iron(II, III) hydroxycarbonate and magnetite were major iron corrosion products...

  11. ROLE OF IRON (II, III) HYDROXYCARBONATE GREEN RUST IN ARSENIC REMEDIATION USING ZEROVALENT IRON IN COLUMN TESTS

    EPA Science Inventory

    We examined corrosion products of zerovalent iron (Peerless iron) that was used in three column tests for removing arsenic under dynamic flow conditions with and without added phosphate and silicate. Iron(II, III) hydroxycarbonate and magnetite were major iron corrosion products...

  12. Electrochemical oxidation by square-wave potential pulses in the imitation of oxidative drug metabolism.

    PubMed

    Nouri-Nigjeh, Eslam; Permentier, Hjalmar P; Bischoff, Rainer; Bruins, Andries P

    2011-07-15

    Electrochemistry combined with mass spectrometry (EC-MS) is an emerging analytical technique in the imitation of oxidative drug metabolism at the early stages of new drug development. Here, we present the benefits of electrochemical oxidation by square-wave potential pulses for the oxidation of lidocaine, a test drug compound, on a platinum electrode. Lidocaine was oxidized at constant potential and by square-wave potential pulses with different cycle times, and the reaction products were analyzed by liquid chromatography-mass spectrometry [LC-MS(/MS)]. Application of constant potentials of up to +5.0 V resulted in relatively low yields of N-dealkylation and 4-hydroxylation products, while oxidation by square-wave potential pulses generated up to 50 times more of the 4-hydroxylation product at cycle times between 0.2 and 12 s (estimated yield of 10%). The highest yield of the N-dealkylation product was obtained at cycle times shorter than 0.2 s. Tuning of the cycle time is thus an important parameter to modulate the selectivity of electrochemical oxidation reactions. The N-oxidation product was only obtained by electrochemical oxidation under air atmosphere due to reaction with electrogenerated hydrogen peroxide. Square-wave potential pulses may also be applicable to modulate the selectivity of electrochemical reactions with other drug compounds in order to generate oxidation products with greater selectivity and higher yield based on the optimization of cycle times and potentials. This considerably widens the scope of direct electrochemistry-based oxidation reactions for the imitation of in vivo oxidative drug metabolism.

  13. Aluminium substitution in iron(II-III)-layered double hydroxides: Formation and cationic order

    SciTech Connect

    Ruby, Christian Abdelmoula, Mustapha; Aissa, Rabha; Medjahdi, Ghouti; Brunelli, Michela; Francois, Michel

    2008-09-15

    The formation and the modifications of the structural properties of an aluminium-substituted iron(II-III)-layered double hydroxide (LDH) of formula Fe{sub 4}{sup II}Fe{sub (2-6y)}{sup III}Al{sub 6y}{sup III} (OH){sub 12} SO{sub 4}, 8H{sub 2}O are followed by pH titration curves, Moessbauer spectroscopy and high-resolution X-ray powder diffraction using synchrotron radiation. Rietveld refinements allow to build a structural model for hydroxysulphate green rust, GR(SO{sub 4}{sup 2-}), i.e. y=0, in which a bilayer of sulphate anions points to the Fe{sup 3+} species. A cationic order is proposed to occur in both GR(SO{sub 4}{sup 2-}) and aluminium-substituted hydroxysulphate green rust when y<0.08. Variation of the cell parameters and a sharp decrease in average crystal size and anisotropy are detected for an aluminium content as low as y=0.01. The formation of Al-GR(SO{sub 4}{sup 2-}) is preceded by the successive precipitation of Fe{sup III} and Al{sup III} (oxy)hydroxides. Adsorption of more soluble Al{sup III} species onto the initially formed ferric oxyhydroxide may be responsible for this slowdown of crystal growth. Therefore, the insertion of low aluminium amount (y{approx}0.01) could be an interesting way for increasing the surface reactivity of iron(II-III) LDH that maintains constant the quantity of the reactive Fe{sup II} species of the material. - Graphical abstract: (a) Crystallographical structure of sulphated green rust: SO{sub 4}{sup 2-} point to the Fe{sup 3+} cations (red) that form an ordered array with the Fe{sup 2+} cations (green). (b) Width and asymmetry of the synchrotron XRD peaks increase rapidly when some Al{sup 3+} species substitute the Fe{sup 3+} cations; z is molar ratio Al{sup 3+}/Fe{sup 3+}.

  14. Assembly and properties of heterobimetallic Co(II/III)/Ca(II) complexes with aquo and hydroxo ligands.

    PubMed

    Lacy, David C; Park, Young Jun; Ziller, Joseph W; Yano, Junko; Borovik, A S

    2012-10-24

    The use of water as a reagent in redox-driven reactions is advantageous because it is abundant and environmentally compatible. The conversion of water to dioxygen in photosynthesis illustrates one example, in which a redox-inactive Ca(II) ion and four manganese ions are required for function. In this report we describe the stepwise formation of two new heterobimetallic complexes containing Co(II/III) and Ca(II) ions and either hydroxo or aquo ligands. The preparation of a four-coordinate Co(II) synthon was achieved with the tripodal ligand, N,N',N"-[2,2',2"-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamido, [MST](3-). Water binds to [Co(II)MST](-) to form the five-coordinate [Co(II)MST(OH(2))](-) complex that was used to prepare the Co(II)/Ca(II) complex [Co(II)MST(μ-OH(2))Ca(II)⊂15-crown-5(OH(2))](+) ([Co(II)(μ-OH(2))Ca(II)OH(2)](+)). [Co(II)(μ-OH(2))CaOH(2)](+) contained two aquo ligands, one bonded to the Ca(II) ion and one bridging between the two metal ions, and thus represents an unusual example of a heterobimetallic complex containing two aquo ligands spanning different metal ions. Both aquo ligands formed intramolecular hydrogen bonds with the [MST](3-) ligand. [Co(II)MST(OH(2))](-) was oxidized to form [Co(III)MST(OH(2))] that was further converted to [Co(III)MST(μ-OH)Ca(II)⊂15-crown-5](+) ([Co(III)(μ-OH)Ca(II)](+)) in the presence of base and Ca(II)OTf(2)/15-crown-5. [Co(III)(μ-OH)Ca(II)](+) was also synthesized from the oxidation of [Co(II)MST](-) with iodosylbenzene (PhIO) in the presence of Ca(II)OTf(2)/15-crown-5. Allowing [Co(III)(μ-OH)Ca(II)](+) to react with diphenylhydrazine afforded [Co(II)(μ-OH(2))Ca(II)OH(2)](+) and azobenzene. Additionally, the characterization of [Co(III)(μ-OH)Ca(II)](+) provides another formulation for the previously reported Co(IV)-oxo complex, [(TMG(3)tren)Co(IV)(μ-O)Sc(III)(OTf)(3)](2+) to one that instead could contain a Co(III)-OH unit.

  15. Selected methods for dissolved iron (II, III) and dissolved sulfide (-II) determinations in geothermal waters

    USGS Publications Warehouse

    Vivit, D.V.; Jenne, E.A.

    1985-01-01

    Dissolved sulfide (-II) and dissolved iron (II, III) were determined in geothermal well water samples collected at Cerro Prieto, Mexico. Most samples consisted of liquid and gas (two phases) at the instant of collection; and a subset of samples, referred to as ' flashed ' samples, consisted of pressurized steam samples which were allowed to condense. Sulfide was determined by sulfide specific ion electrode; Fe(II) and Fe(III) plus Fe(II) were determined spectrophotometrically. The precision and accuracy of the methods were evaluated for these high-silica waters with replicate analyses, spike recoveries, and an alternate method. Direct current (d.c.) argon plasma emission spectrometry was the alternate method used for Fe(III)-plus-Fe(II) analyses. Mean dissolved iron concentrations ranged from 20.2 to 834 micrograms/L (ug/L) as Fe(II) and 26.8 to 904 ug/L as Fe(III) plus Fe(II). Mean sulfide concentrations ranged from about 0.01 to 5.3 mg/L (S-II) Generally, higher S(-II) values and larger Fe(II)/Fe(III) ratios were found in the two-phase samples. These findings suggest that the ' flashed ' samples are at a less reduced state than the two-phase samples. (Author 's abstract)

  16. Water ice phases II, III, and V - Plastic deformation and phase relationships

    NASA Technical Reports Server (NTRS)

    Durham, W. B.; Boro, C. O.; Kirby, S. H.; Stern, L. A.; Heard, H. C.

    1988-01-01

    The ordinary water phase I was transformed to the ice phases that are known to exist in the interiors of large ice moons, such as Ganymede and Callisto for the purpose of investigating plastic deformation behavior of these ices. Ices II, III, and V were prepared using an apparatus and techniques similar to those described by Durham et al. (1983) and subsequently deformed in a gas deformation apparatus, and their deformation data were obtained. It was found that ice II was the strongest of the high-pressure phases, with a strength that was comparable to that of ice I; ice III was very weak, with the flow rate 100 to 1000 times higher than that of ice II at the same levels of stress. It was also found that ices III and V can exist metastably within the ice II field and that they may be deformed plastically within much of the metastable region without reverting to ice II. It is suggested that the weakness of the ice III phase may have profoundly influenced the evolution and the present-day behavior of the icy moons.

  17. Soft recovery of polytetrafluoroethylene shocked through the crystalline phase II-III transition

    NASA Astrophysics Data System (ADS)

    Brown, E. N.; Trujillo, C. P.; Gray, G. T.; Rae, P. J.; Bourne, N. K.

    2007-01-01

    Polymers are increasingly being utilized as monolithic materials and composite matrices for structural applications historically reserved for metals. High strain-rate applications in aerospace, defense, and the automotive industries have lead to interest in the shock response of polytetrafluoroethylene (PTFE) and the ensuing changes in polymer structure due to shock prestraining. We present an experimental study of crystalline structure evolution due to pressure-induced phase transitions in a semicrystalline polymer using soft-recovery, shock loading techniques coupled with mechanical and chemical postshock analyses. Gas-launched, plate impact experiments have been performed on pedigreed PTFE 7C, mounted in momentum trapped, shock assemblies, with impact pressures above and below the phase II to phase III crystalline transition. Below the phase transition only subtle changes were observed in the crystallinity, microstructure, and mechanical response of PTFE. Shock loading of PTFE 7C above the phase II-III transition was seen to cause both an increase in crystallinity from 38% to ˜53% (by differential scanning calorimetry) and a finer crystalline microstructure, and changed the yield and flow stress behavior.

  18. Water ice phases II, III, and V - Plastic deformation and phase relationships

    NASA Technical Reports Server (NTRS)

    Durham, W. B.; Boro, C. O.; Kirby, S. H.; Stern, L. A.; Heard, H. C.

    1988-01-01

    The ordinary water phase I was transformed to the ice phases that are known to exist in the interiors of large ice moons, such as Ganymede and Callisto for the purpose of investigating plastic deformation behavior of these ices. Ices II, III, and V were prepared using an apparatus and techniques similar to those described by Durham et al. (1983) and subsequently deformed in a gas deformation apparatus, and their deformation data were obtained. It was found that ice II was the strongest of the high-pressure phases, with a strength that was comparable to that of ice I; ice III was very weak, with the flow rate 100 to 1000 times higher than that of ice II at the same levels of stress. It was also found that ices III and V can exist metastably within the ice II field and that they may be deformed plastically within much of the metastable region without reverting to ice II. It is suggested that the weakness of the ice III phase may have profoundly influenced the evolution and the present-day behavior of the icy moons.

  19. ROTATION OF THE K3 II-III GIANT STAR {alpha} HYDRA

    SciTech Connect

    Gray, David F.

    2013-08-01

    Fundamental spectroscopic determination of projected rotation rates of slowly rotating stars is challenging because the rotational broadening of the spectral lines is often comparable to, or smaller than, the broadening from other sources, most notably macroturbulence. Fourier techniques have the advantage over direct profile matching when the observed profiles are complete, but when the profiles are severely blended, the Fourier analysis is compromised. A process of modeling partial profiles for determining the rotation rate for stars having blended spectral lines is investigated and applied to the evolved star {alpha} Hya (K3 II-III). Projected rotation higher than 5 km s{sup -1} can be definitively ruled out for this star. Not all lines are equally good, depending on the amount of blending and also depending on the strength of the line, as the balance between the thermal and non-thermal components changes. A modest ambiguity arises between macroturbulence and rotational broadening, but a careful look at the differences between the observations and the models allows one to measure the rotation with acceptable precision. The result for {alpha} Hya is v sin i = 2.6 {+-} 0.3 km s{sup -1}.

  20. RELATIONSHIPS BETWEEN OXIDATION-REDUCTION POTENTIAL, OXIDANT, AND PH IN DRINKING WATER

    EPA Science Inventory

    Oxidation and reduction (redox) reactions are very important in drinking water. Oxidation-reduction potential (ORP) measurements reflect the redox state of water. Redox measurements are not widely made by drinking water utilities in part because they are not well understood. The ...

  1. RELATIONSHIPS BETWEEN OXIDATION-REDUCTION POTENTIAL, OXIDANT, AND PH IN DRINKING WATER

    EPA Science Inventory

    Oxidation and reduction (redox) reactions are very important in drinking water. Oxidation-reduction potential (ORP) measurements reflect the redox state of water. Redox measurements are not widely made by drinking water utilities in part because they are not well understood. The ...

  2. Effects of the electrode oxidizing potential on underwater wet welds

    SciTech Connect

    Pope, A.M.; Liu, S.; Olson, D.L.

    1994-12-31

    Depth greatly affects the chemical composition and mechanical properties of underwater wet (UWW) welds. It is well documented in the literature that as depth increases, the amount of oxygen in the weld increases while the deoxidants decrease in concentration. To understand the influence of oxygen on the characteristics and properties of UWW welds, deposits of electrodes with different oxidizing potentials were studied. The oxidizing potentials of these electrodes were varied through additions of hematite (Fe{sub 2}O{sub 3}) to the covering of a ruffle electrode. No metallic deoxidants were used in the coverings, but MgO was added to one of the oxidizing electrodes as a possible way to control oxygen. The welds were made at 0.5 m of water depth. Chemical analysis showed that increasing oxidizing potential of the electrodes increased the weld metal oxygen content eventually reaching a plateau value of approximately 2,100 ppm. This concentration plateau is determined by the solubility limit of FeO in the liquid iron at the solidification temperature. The MgO addition was sufficient to reduce the oxygen level to 1,700 ppm. The results also showed that the effects of increasing oxidizing potential of the electrode covering on weld metal composition and microstructure are similar to those of increasing water depth. This finding is very significant since it allows for the simulation of deep water weld metal microstructures in shallow waters by controlling the oxidizing potential of the consumables used. Finally, studying the properties of oxidizing electrodes in shallow depths will also be useful in developing welding electrodes for deep waters.

  3. Potential role of punicalagin against oxidative stress induced testicular damage

    PubMed Central

    Rao, Faiza; Tian, Hui; Li, Wenqing; Hung, Helong; Sun, Fei

    2016-01-01

    Punicalagin is isolated from pomegranate and widely used for the treatment of different diseases in Chinese traditional medicine. This study aimed to evaluate the effect of Punicalagin (purity ≥98%) on oxidative stress induced testicular damage and its effect on fertility. We detected the antioxidant potential of punicalagin in lipopolysaccharide (LPS) induced oxidative stress damage in testes, also tried to uncover the boosting fertility effect of Punicalagin (PU) against oxidative stress-induced infertility. Results demonstrated that 9 mg kg−1 for 7 days treatment significantly decreases LPS induced oxidative damage in testes and nitric oxide production. The administration of oxidative stress resulted in a significant reduction in testes antioxidants GSH, T-SOD, and CAT raised LPO, but treatment with punicalagin for 7 days increased antioxidant defense GSH, T-SOD, and CAT by the end of the experiment and reduced LPO level as well. PU also significantly activates Nrf2, which is involved in regulation of antioxidant defense systems. Hence, the present research categorically elucidates the protective effect of punicalagin against LPS induced oxidative stress induced perturbation in the process of spermatogenesis and significantly increased sperm health and number. Moreover, fertility success significantly decreased in LPS-injected mice compared to controls. Mice injected with LPS had fertility indices of 12.5%, while others treated with a combination of PU + LPS exhibited 75% indices. By promoting fertility and eliminating oxidative stress and inflammation, PU may be a useful nutrient for the treatment of infertility. PMID:26763544

  4. Potential role of punicalagin against oxidative stress induced testicular damage.

    PubMed

    Rao, Faiza; Tian, Hui; Li, Wenqing; Hung, Helong; Sun, Fei

    2016-01-01

    Punicalagin is isolated from pomegranate and widely used for the treatment of different diseases in Chinese traditional medicine. This study aimed to evaluate the effect of Punicalagin (purity ≥98%) on oxidative stress induced testicular damage and its effect on fertility. We detected the antioxidant potential of punicalagin in lipopolysaccharide (LPS) induced oxidative stress damage in testes, also tried to uncover the boosting fertility effect of Punicalagin (PU) against oxidative stress-induced infertility. Results demonstrated that 9 mg kg-1 for 7 days treatment significantly decreases LPS induced oxidative damage in testes and nitric oxide production. The administration of oxidative stress resulted in a significant reduction in testes antioxidants GSH, T-SOD, and CAT raised LPO, but treatment with punicalagin for 7 days increased antioxidant defense GSH, T-SOD, and CAT by the end of the experiment and reduced LPO level as well. PU also significantly activates Nrf2, which is involved in regulation of antioxidant defense systems. Hence, the present research categorically elucidates the protective effect of punicalagin against LPS induced oxidative stress induced perturbation in the process of spermatogenesis and significantly increased sperm health and number. Moreover, fertility success significantly decreased in LPS-injected mice compared to controls. Mice injected with LPS had fertility indices of 12.5%, while others treated with a combination of PU + LPS exhibited 75% indices. By promoting fertility and eliminating oxidative stress and inflammation, PU may be a useful nutrient for the treatment of infertility.

  5. Risk of node metastasis of sentinel lymph nodes detected in level II/III of the axilla by single-photon emission computed tomography/computed tomography

    PubMed Central

    SHIMA, HIROAKI; KUTOMI, GORO; SATOMI, FUKINO; MAEDA, HIDEKI; TAKAMARU, TOMOKO; KAMESHIMA, HIDEKAZU; OMURA, TOSEI; MORI, MITSURU; HATAKENAKA, MASAMITSU; HASEGAWA, TADASHI; HIRATA, KOICHI

    2014-01-01

    In breast cancer, single-photon emission computed tomography/computed tomography (SPECT/CT) shows the exact anatomical location of sentinel nodes (SN). SPECT/CT mainly exposes axilla and partly exposes atypical sites of extra-axillary lymphatic drainage. The mechanism of how the atypical hot nodes are involved in lymphatic metastasis was retrospectively investigated in the present study, particularly at the level II/III region. SPECT/CT was performed in 92 clinical stage 0-IIA breast cancer patients. Sentinel lymph nodes are depicted as hot nodes in SPECT/CT. Patients were divided into two groups: With or without hot node in level II/III on SPECT/CT. The existence of metastasis in level II/III was investigated and the risk factors were identified. A total of 12 patients were sentinel lymph node biopsy metastasis positive and axillary lymph node dissection (ALND) was performed. These patients were divided into two groups: With and without SN in level II/III, and nodes in level II/III were pathologically proven. In 11 of the 92 patients, hot nodes were detected in level II/III. There was a significant difference in node metastasis depending on whether there were hot nodes in level II/III (P=0.0319). Multivariate analysis indicated that the hot nodes in level II/III and lymphatic invasion were independent factors associated with node metastasis. There were 12 SN-positive patients followed by ALND. In four of the 12 patients, hot nodes were observed in level II/III. Two of the four patients with hot nodes depicted by SPECT/CT and metastatic nodes were pathologically evident in the same lesion. Therefore, the present study indicated that the hot node in level II/III as depicted by SPECT/CT may be a risk of SN metastasis, including deeper nodes. PMID:25289038

  6. Risk of node metastasis of sentinel lymph nodes detected in level II/III of the axilla by single-photon emission computed tomography/computed tomography.

    PubMed

    Shima, Hiroaki; Kutomi, Goro; Satomi, Fukino; Maeda, Hideki; Takamaru, Tomoko; Kameshima, Hidekazu; Omura, Tosei; Mori, Mitsuru; Hatakenaka, Masamitsu; Hasegawa, Tadashi; Hirata, Koichi

    2014-11-01

    In breast cancer, single-photon emission computed tomography/computed tomography (SPECT/CT) shows the exact anatomical location of sentinel nodes (SN). SPECT/CT mainly exposes axilla and partly exposes atypical sites of extra-axillary lymphatic drainage. The mechanism of how the atypical hot nodes are involved in lymphatic metastasis was retrospectively investigated in the present study, particularly at the level II/III region. SPECT/CT was performed in 92 clinical stage 0-IIA breast cancer patients. Sentinel lymph nodes are depicted as hot nodes in SPECT/CT. Patients were divided into two groups: With or without hot node in level II/III on SPECT/CT. The existence of metastasis in level II/III was investigated and the risk factors were identified. A total of 12 patients were sentinel lymph node biopsy metastasis positive and axillary lymph node dissection (ALND) was performed. These patients were divided into two groups: With and without SN in level II/III, and nodes in level II/III were pathologically proven. In 11 of the 92 patients, hot nodes were detected in level II/III. There was a significant difference in node metastasis depending on whether there were hot nodes in level II/III (P=0.0319). Multivariate analysis indicated that the hot nodes in level II/III and lymphatic invasion were independent factors associated with node metastasis. There were 12 SN-positive patients followed by ALND. In four of the 12 patients, hot nodes were observed in level II/III. Two of the four patients with hot nodes depicted by SPECT/CT and metastatic nodes were pathologically evident in the same lesion. Therefore, the present study indicated that the hot node in level II/III as depicted by SPECT/CT may be a risk of SN metastasis, including deeper nodes.

  7. Significance of iron(II,III) hydroxycarbonate green rust in arsenic remediation using zerovalent iron in laboratory column tests.

    PubMed

    Su, Chunming; Puls, Robert W

    2004-10-01

    We examined the corrosion products of zerovalent iron used in three column tests for removing arsenic from water under dynamic flow conditions. Each column test lasted 3-4 months using columns consisting of a 10.3-cm depth of 50:50 (w:w, Peerless iron:sand) in the middle and a 10.3cm depth of a sediment from Elizabeth City, NC, in both upper and lower portions of the 31-cm-long glass column (2.5 cm in diameter). The feeding solutions were 1 mg of As(V) L(-1) + 1 mg of As(III) L(-1) in 7 mM NaCl + 0.86 mM CaSO4 with or without added phosphate (0.5 or 1 mg of P L(-1)) and silicate (10 or 20 mg of Si L(-1)) at pH 6.5. Iron(II,III) hydroxycarbonate green rust (or simply, carbonate green rust) and magnetite were the major iron corrosion products identified with X-ray diffraction for the separated fractions (5 and 1 min sedimentation and residual). The presence of carbonate green rust was confirmed by scanning electron microscopy (hexagonal morphology) and FTIR-photoacoustic spectroscopy (interlayer carbonate stretching mode at 1352-1365 cm(-1)). X-ray photoelectron spectroscopy investigation revealed the presence of predominantly As(V) at the surface of corroded iron particles despite the fact that the feeding solution in contact with Peerless iron contained more As(III) than As(V) as a result of a preferential uptake of As(V) over As(III) by the Elizabeth City sediment. Extraction of separated corrosion products with 1.0 M HCI showed that from 86 to 96% of the total extractable As (6.9-14.6 g kg(-1)) was in the form of As(V) in agreement with the XPS results. Combined microscopic and macroscopic wet chemistry results suggest that sorbed As(III) was partially oxidized by the carbonate green rust at the early stage of iron corrosion. The column experiments suggest that either carbonate green rust is kinetically favored or is thermodynamically more stable than sulfate green rust in the studied Peerless iron corrosion systems.

  8. Magnetoviscoelastic characteristics of superparamagnetic oxides (Fe, Ni) based ferrofluids

    NASA Astrophysics Data System (ADS)

    Katiyar, Ajay; Dhar, Purbarun; Nandi, Tandra; Das, Sarit K.

    2017-08-01

    Ferrofluids have been popular among the academic and scientific communities owing to their intelligent physical characteristics under external stimuli and are in fact among the first nanotechnology products to be employed in real world applications. However, studies on the magnetoviscoelastic behavior of concentrated ferrofluids, especially of superparamagnetic oxides of iron and nickel are rare. The present article comprises the formulation of magneto-colloids utilizing the three various metal oxides nanoparticles viz. Iron (II, III) oxide (Fe3O4), Iron (III) oxide (Fe2O3) and Nickel oxide (NiO) in oil. Iron (II, III) oxide based colloids demonstrate high magnetoviscous characteristics over the other oxides based colloids under external magnetic fields. The maximum magnitude of yield stress and viscosity is found to be 3.0 kPa and 2.9 kPa.s, respectively for iron (II, III) oxide based colloids at 2.6 vol% particle concentration and 1.2 T magnetic field. Experimental investigations reveal that the formulated magneto-nanocolloids are stable, even in high magnetic fields and almost reversible when exposed to rising and drop of magnetic fields of the same magnitude. Observations also reveal that the elastic behavior dominates over the viscous behavior with enhanced relaxation and creep characteristics under the magnetic field. The effect of temperature on viscosity and yield stress of magneto-nanocolloids under magnetic fields has also been discussed. Thus, the present findings have potential applications in various fields such as electromagnetic clutch and brakes of automotive, damping, sealing, optics, nanofinishing etc.

  9. Transition Metal Oxide Alloys as Potential Solar Energy Conversion Materials

    SciTech Connect

    Toroker, Maytal; Carter, Emily A.

    2013-02-21

    First-row transition metal oxides (TMOs) are inexpensive potentia alternative materials for solar energy conversion devices. However, some TMOs, such as manganese(II) oxide, have band gaps that are too large for efficiently absorbing solar energy. Other TMOs, such as iron(II) oxide, have conduction and valence band edges with the same orbital character that may lead to unfavorably high electron–hole recombination rates. Another limitation of iron(II) oxide is that the calculated valence band edge is not positioned well for oxidizing water. We predict that key properties, including band gaps, band edge positions, and possibly electron–hole recombination rates, may be improved by alloying TMOs that have different band alignments. A new metric, the band gap center offset, is introduced for simple screening of potential parent materials. The concept is illustrated by calculating the electronic structure of binary oxide alloys that contain manganese, nickel, iron, zinc, and/or magnesium, within density functional theory (DFT)+U and hybrid DFT theories. We conclude that alloys of iron(II) oxide are worth evaluating further as solar energy conversion materials.

  10. Morphine as a Potential Oxidative Stress-Causing Agent.

    PubMed

    Skrabalova, Jitka; Drastichova, Zdenka; Novotny, Jiri

    2013-11-01

    Morphine exhibits important pharmacological effects for which it has been used in medical practice for quite a long time. However, it has a high addictive potential and can be abused. Long-term use of this drug can be connected with some pathological consequences including neurotoxicity and neuronal dysfunction, hepatotoxicity, kidney dysfunction, oxidative stress and apoptosis. Therefore, most studies examining the impact of morphine have been aimed at determining the effects induced by chronic morphine exposure in the brain, liver, cardiovascular system and macrophages. It appears that different tissues may respond to morphine diversely and are distinctly susceptible to oxidative stress and subsequent oxidative damage of biomolecules. Importantly, production of reactive oxygen/nitrogen species induced by morphine, which have been observed under different experimental conditions, can contribute to some pathological processes, degenerative diseases and organ dysfunctions occurring in morphine abusers or morphine-treated patients. This review attempts to provide insights into the possible relationship between morphine actions and oxidative stress.

  11. FKBP12 modulation of the binding of the skeletal ryanodine receptor onto the II-III loop of the dihydropyridine receptor.

    PubMed Central

    O'Reilly, Fiona M; Robert, Mylène; Jona, Istvan; Szegedi, Csaba; Albrieux, Mireille; Geib, Sandrine; De Waard, Michel; Villaz, Michel; Ronjat, Michel

    2002-01-01

    In skeletal muscle, excitation-contraction coupling involves a functional interaction between the ryanodine receptor (RyR) and the dihydropyridine receptor (DHPR). The domain corresponding to Thr(671)-Leu(690) of the II-III loop of the skeletal DHPR alpha(1)-subunit is able to regulate RyR properties and calcium release from sarcoplasmic reticulum, whereas the domain corresponding to Glu(724)-Pro(760) antagonizes this effect. Two peptides, covering these sequences (peptide A(Sk) and C(Sk), respectively) were immobilized on polystyrene beads. We demonstrate that peptide A(Sk) binds to the skeletal isoform of RyR (RyR1) whereas peptide C(Sk) does not. Using surface plasmon resonance detection, we show that 1) domain Thr(671)-Leu(690) is the only sequence of the II-III loop binding with RyR1 and 2) the interaction of peptide A(Sk) with RyR1 is not modulated by Ca(2+) (pCa 9-2) nor by Mg(2+) (up to 10 mM). In contrast, this interaction is strongly potentiated by the immunophilin FKBP12 (EC(50) = 10 nM) and inhibited by both rapamycin (IC(50) = 5 nM) and FK506. Peptide A(Sk) induces a 300% increase of the opening probability of the RyR1 incorporated in lipid bilayer. Removal of FKBP12 from RyR1 completely abolishes this effect of domain A(Sk) on RyR1 channel behavior. These results demonstrate a direct interaction of the RyR1 with the discrete domain of skeletal DHPR alpha(1)-subunit corresponding to Thr(671)-Leu(690) and show that the association of FKBP12 with RyR1 specifically modulates this interaction. PMID:11751303

  12. In-situ X-Ray Absorption Spectroscopy (XAS) Investigation of a Bifunctional Manganese Oxide Catalyst with High Activity for Electrochemical Water Oxidation and Oxygen Reduction

    PubMed Central

    Benck, Jesse D.; Gul, Sheraz; Webb, Samuel M.; Yachandra, Vittal K.; Yano, Junko; Jaramillo, Thomas F.

    2013-01-01

    In-situ x-ray absorption spectroscopy (XAS) is a powerful technique that can be applied to electrochemical systems, with the ability to elucidate the chemical nature of electrocatalysts under reaction conditions. In this study, we perform in-situ XAS measurements on a bifunctional manganese oxide (MnOx) catalyst with high electrochemical activity for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Using x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS), we find that exposure to an ORR-relevant potential of 0.7 V vs. RHE produces a disordered Mn3II,III,IIIO4 phase with negligible contributions from other phases. After the potential is increased to a highly anodic value of 1.8 V vs. RHE, relevant to the OER, we observe an oxidation of approximately 80% of the catalytic thin film to form a mixed MnIII,IV oxide, while the remaining 20% of the film consists of a less oxidized phase, likely corresponding to unchanged Mn3II,III,IIIO4. XAS and electrochemical characterization of two thin film catalysts with different MnOx thicknesses reveals no significant influence of thickness on the measured oxidation states, at either ORR or OER potentials, but demonstrates that the OER activity scales with film thickness. This result suggests that the films have porous structure, which does not restrict electrocatalysis to the top geometric layer of the film. As the portion of the catalyst film that is most likely to be oxidized at the high potentials necessary for the OER is that which is closest to the electrolyte interface, we hypothesize that the MnIII,IV oxide, rather than Mn3II,III,IIIO4, is the phase pertinent to the observed OER activity. PMID:23758050

  13. Spectroscopic and quantum chemical study of the structure of a new paramagnetic dimeric palladium(II,III) complex with creatine

    NASA Astrophysics Data System (ADS)

    Mitewa, Mariana; Enchev, Venelin; Bakalova, Tatyana

    2002-05-01

    The structure and coordination mode of the newly synthesized dimeric paramagnetic Pd(II,III) complex are studied using magneto-chemical, EPR and IR spectroscopic methods. In order to perform reliable assignment of the IR bands, the structure and IR spectrum of the free creatine were calculated using ab initio method. For calculation of the configuration of its deprotonated and doubly deprotonated forms the semiempirical AM1 method was used.

  14. Predictive tests to evaluate oxidative potential of engineered nanomaterials

    NASA Astrophysics Data System (ADS)

    Ghiazza, Mara; Carella, Emanuele; Oliaro-Bosso, Simonetta; Corazzari, Ingrid; Viola, Franca; Fenoglio, Ivana

    2013-04-01

    Oxidative stress constitutes one of the principal injury mechanisms through which particulate toxicants (asbestos, crystalline silica, hard metals) and engineered nanomaterials can induce adverse health effects. ROS may be generated indirectly by activated cells and/or directly at the surface of the material. The occurrence of these processes depends upon the type of material. Many authors have recently demonstrated that metal oxides and carbon-based nanoparticles may influence (increasing or decreasing) the generation of oxygen radicals in a cell environment. Metal oxide, such as iron oxides, crystalline silica, and titanium dioxide are able to generate free radicals via different mechanisms causing an imbalance within oxidant species. The increase of ROS species may lead to inflammatory responses and in some cases to the development of cancer. On the other hand carbon-based nanomaterials, such as fullerene, carbon nanotubes, carbon black as well as cerium dioxide are able to scavenge the free radicals generated acting as antioxidant. The high numbers of new-engineered nanomaterials, which are introduced in the market, are exponentially increasing. Therefore the definition of toxicological strategies is urgently needed. The development of acellular screening tests will make possible the reduction of the number of in vitro and in vivo tests to be performed. An integrated protocol that may be used to predict the oxidant/antioxidant potential of engineered nanoparticles will be here presented.

  15. Potential for microbial oxidation of ferrous iron in basaltic glass.

    PubMed

    Xiong, Mai Yia; Shelobolina, Evgenya S; Roden, Eric E

    2015-05-01

    Basaltic glass (BG) is an amorphous ferrous iron [Fe(II)]-containing material present in basaltic rocks, which are abundant on rocky planets such as Earth and Mars. Previous research has suggested that Fe(II) in BG can serve as an energy source for chemolithotrophic microbial metabolism, which has important ramifications for potential past and present microbial life on Mars. However, to date there has been no direct demonstration of microbially catalyzed oxidation of Fe(II) in BG. In this study, three different culture systems were used to investigate the potential for microbial oxidation of Fe(II) in BG, including (1) the chemolithoautotrophic Fe(II)-oxidizing, nitrate-reducing "Straub culture"; (2) the mixotrophic Fe(II)-oxidizing, nitrate-reducing organism Desulfitobacterium frappieri strain G2; and (3) indigenous microorganisms from a streambed Fe seep in Wisconsin. The BG employed consisted of clay and silt-sized particles of freshly quenched lava from the TEB flow in Kilauea, Hawaii. Soluble Fe(II) or chemically reduced NAu-2 smectite (RS) were employed as positive controls to verify Fe(II) oxidation activity in the culture systems. All three systems demonstrated oxidation of soluble Fe(II) and/or structural Fe(II) in RS, whereas no oxidation of Fe(II) in BG material was observed. The inability of the Straub culture to oxidize Fe(II) in BG was particularly surprising, as this culture can oxidize other insoluble Fe(II)-bearing minerals such as biotite, magnetite, and siderite. Although the reason for the resistance of the BG toward enzymatic oxidation remains unknown, it seems possible that the absence of distinct crystal faces or edge sites in the amorphous glass renders the material resistant to such attack. These findings have implications with regard to the idea that Fe(II)-Si-rich phases in basalt rocks could provide a basis for chemolithotrophic microbial life on Mars, specifically in neutral-pH environments where acid-promoted mineral dissolution and

  16. Mitochondrial membrane potential: a novel biomarker of oxidative environmental stress.

    PubMed Central

    Vayssier-Taussat, Muriel; Kreps, Sarah E; Adrie, Christophe; Dall'Ava, Josette; Christiani, David; Polla, Barbara S

    2002-01-01

    Epidemiologic analyses, traditionally based on long-term cohort or case-control studies, provide retrospective causal associations between exposure to a particular environmental stressor and an exposure-related disease end point. Recent research initiatives have propelled a shift toward exploring molecular epidemiology and molecular biological markers (biomarkers) as a means of providing more immediate, quantitative risk assessment of potentially deleterious environmental exposures. We compared, in normal human monocytes isolated from the blood of healthy donors, variations in Hsp70 expression and mitochondrial membrane potential (delta psi m) in response to exposure to either tobacco smoke or gamma-irradiation, two models for environmentally mediated oxidant exposure. On the basis of its mechanistic specificity for oxidants and little baseline variation in cells from distinct individuals, we propose that delta psi m represents a selective in vitro and in vivo biomarker for oxidant exposure. delta psi m may be used to gauge risks associated with oxidant-mediated air pollution and radiation. PMID:11882482

  17. Potential toxicity of superparamagnetic iron oxide nanoparticles (SPION)

    PubMed Central

    Singh, Neenu; Jenkins, Gareth J.S.; Asadi, Romisa; Doak, Shareen H.

    2010-01-01

    Superparamagnetic iron oxide nanoparticles (SPION) are being widely used for various biomedical applications, for example, magnetic resonance imaging, targeted delivery of drugs or genes, and in hyperthermia. Although, the potential benefits of SPION are considerable, there is a distinct need to identify any potential cellular damage associated with these nanoparticles. Besides focussing on cytotoxicity, the most commonly used determinant of toxicity as a result of exposure to SPION, this review also mentions the importance of studying the subtle cellular alterations in the form of DNA damage and oxidative stress. We review current studies and discuss how SPION, with or without different surface coating, may cause cellular perturbations including modulation of actin cytoskeleton, alteration in gene expression profiles, disturbance in iron homeostasis and altered cellular responses such as activation of signalling pathways and impairment of cell cycle regulation. The importance of protein-SPION interaction and various safety considerations relating to SPION exposure are also addressed. PMID:22110864

  18. Redox Potentials, Laccase Oxidation, and Antilarval Activities of Substituted Phenols

    PubMed Central

    Prasain, Keshar; Nguyen, Thi D. T.; Gorman, Maureen J.; Barrigan, Lydia M.; Peng, Zeyu; Kanost, Michael R.; Syed, Lateef U.; Li, Jun; Zhu, Kun Yan; Hua, Duy H.

    2012-01-01

    Laccases are copper-containing oxidases that are involved in sclerotization of the cuticle of mosquitoes and other insects. Oxidation of exogenous compounds by insect laccases may have the potential to produce reactive species toxic to insects. We investigated two classes of substituted phenolic compounds, halogenated di- and trihydroxybenzenes and substituted di-tert-butylphenols, on redox potential, oxidation by laccase and effects on mosquito larval growth. An inverse correlation between the oxidation potentials and laccase activity of halogenated hydroxybenzenes was found. Substituted di-tert-butylphenols however were found to impact mosquito larval growth and survival. In particular, 2,4-di-tert-butyl-6-(3-methyl-2-butenyl)phenol (15) caused greater than 98% mortality of Anopheles gambiae larvae in a concentration of 180 nM, whereas 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-methylpropanal oxime (13) and 6,8-di-tert-butyl-2,2-dimethyl-3,4-dihydro-2H-chromene (33) caused 93% and 92% mortalities in concentrations of 3.4 and 3.7 μM, respectively. Larvae treated with di-tert-butylphenolic compounds died just before pupation. PMID:22300888

  19. Heterogeneous oxidation of SO2 by O3-aged black carbon and its dithiothreitol oxidative potential.

    PubMed

    Xu, Weiwei; Li, Qian; Shang, Jing; Liu, Jia; Feng, Xiang; Zhu, Tong

    2015-10-01

    Ozone (O3) is an important atmospheric oxidant. Black carbon (BC) particles released into the atmosphere undergo an aging process via O3 oxidation. O3-aged BC particles may change their uptake ability toward trace reducing gases such as SO2 in the atmosphere, leading to different environmental and health effects. In this paper, the heterogeneous reaction process between O3-aged BC and SO2 was explored via in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Combined with ion chromatography (IC), DRIFTS was used to qualitatively and quantitatively analyze the sulfate product. The results showed that O3-aged BC had stronger SO2 oxidation ability than fresh BC, and the reactive species/sites generated on the surface had an important role in the oxidation of SO2. Relative humidity or 254nm UV (ultraviolet) light illumination enhanced the oxidation uptake of SO2 on O3-aged BC. The oxidation potentials of the BC particles were detected via dithiothreitol (DTT) assay. The DTT activity over BC was decreased in the process of SO2 reduction, with the consumption of oxidative active sites. Copyright © 2015. Published by Elsevier B.V.

  20. Iron oxide reduction in deep Baltic Sea sediments: the potential role of anaerobic oxidation of methane

    NASA Astrophysics Data System (ADS)

    Egger, Matthias; Slomp, Caroline P.; Dijkstra, Nikki; Sapart, Célia J.; Risgaard-Petersen, Nils; Kasten, Sabine; Riedinger, Natascha; Barker Jørgensen, Bo

    2015-04-01

    Methane is a powerful greenhouse gas and its emission from marine sediments to the atmosphere is largely controlled by anaerobic oxidation of methane (AOM). Traditionally, sulfate is considered to be the most important electron acceptor for AOM in marine sediments. However, recent studies have shown that AOM may also be coupled to the reduction of iron (Fe) oxides (Beal et al., 2009; Riedinger et al., 2014; Egger et al., 2014). In the Baltic Sea, the transition from the Ancylus freshwater phase to the Littorina brackish/marine phase (A/L-transition) ca. 9-7 ka ago (Zillén et al., 2008) resulted in the accumulation of methanogenic brackish/marine sediments overlying Fe-oxide rich lacustrine deposits. The downward diffusion of methane from the brackish/marine sediments into the lake sediments leads to an ideal diagenetic system to study a potential coupling between Fe oxide reduction and methane oxidation. Here, we use porewater and sediment geochemical data obtained at sites M0063 and M0065 during the IODP Baltic Sea Paleoenvironment Expedition 347 in 2013 to identify the potential mechanisms responsible for the apparent Fe oxide reduction in the non-sulfidic limnic sediments below the A/L transition. In this presentation, we will review the various explanations for the elevated ferrous Fe in the porewater in the lake sediments and we will specifically address the potential role of the reaction of methane with Fe-oxides. References: Beal E. J., House C. H. and Orphan V. J. (2009) Manganese- and iron-dependent marine methane oxidation. Science 325, 184-187. Egger M., Rasigraf O., Sapart C. J., Jilbert T., Jetten M. S. M., Röckmann T., van der Veen C., Banda N., Kartal B., Ettwig K. F. and Slomp C. P. (2014) Iron-mediated anaerobic oxidation of methane in brackish coastal sediments. Environ. Sci. Technol. 49, 277-283. Riedinger N., Formolo M. J., Lyons T. W., Henkel S., Beck A. and Kasten S. (2014) An inorganic geochemical argument for coupled anaerobic oxidation of

  1. Oxidative potential of subway PM2.5

    NASA Astrophysics Data System (ADS)

    Moreno, Teresa; Kelly, Frank J.; Dunster, Chrissi; Oliete, Ana; Martins, Vânia; Reche, Cristina; Minguillón, Maria Cruz; Amato, Fulvio; Capdevila, Marta; de Miguel, Eladio; Querol, Xavier

    2017-01-01

    Air quality in subway systems is of interest not only because particulate matter (PM) concentrations can be high, but also because of the peculiarly metalliferous chemical character of the particles, most of which differ radically from those of outdoor ambient air. We report on the oxidative potential (OP) of PM2.5 samples collected in the Barcelona subway system in different types of stations. The PM chemical composition of these samples showed typically high concentrations of Fe, Total Carbon, Ba, Cu, Mn, Zn and Cr sourced from rail tracks, wheels, catenaries, brake pads and pantographs. Two toxicological indicators of oxidative activity, ascorbic acid (AA) oxidation (expressed as OPAA μg-1 or OPAA m-3) and glutathione (GSH) oxidation (expressed as OPGSH μg-1 or OPGSH m-3), showed low OP for all samples (compared with outdoor air) but considerable variation between stations (0.9-2.4 OPAA μg-1; 0.4-1.9 OPGSH μg-1). Results indicate that subway PM toxicity is not related to variations in PM2.5 concentrations produced by ventilation changes, tunnel works, or station design, but may be affected more by the presence of metallic trace elements such as Cu and Sb sourced from brakes and pantographs. The OP assays employed do not reveal toxic effects from the highly ferruginous component present in subway dust.

  2. Morphine as a Potential Oxidative Stress-Causing Agent

    PubMed Central

    Skrabalova, Jitka; Drastichova, Zdenka; Novotny, Jiri

    2013-01-01

    Morphine exhibits important pharmacological effects for which it has been used in medical practice for quite a long time. However, it has a high addictive potential and can be abused. Long-term use of this drug can be connected with some pathological consequences including neurotoxicity and neuronal dysfunction, hepatotoxicity, kidney dysfunction, oxidative stress and apoptosis. Therefore, most studies examining the impact of morphine have been aimed at determining the effects induced by chronic morphine exposure in the brain, liver, cardiovascular system and macrophages. It appears that different tissues may respond to morphine diversely and are distinctly susceptible to oxidative stress and subsequent oxidative damage of biomolecules. Importantly, production of reactive oxygen/nitrogen species induced by morphine, which have been observed under different experimental conditions, can contribute to some pathological processes, degenerative diseases and organ dysfunctions occurring in morphine abusers or morphine-treated patients. This review attempts to provide insights into the possible relationship between morphine actions and oxidative stress. PMID:24376392

  3. Group II/III metabotropic glutamate receptors exert endogenous activity-dependent modulation of TRPV1 receptors on peripheral nociceptors

    PubMed Central

    Carlton, Susan M.; Zhou, Shengtai; Govea, Rosann; Du, Junhui

    2011-01-01

    There is pharmacological evidence Group II and III metabotropic glutamate receptors (mGluRs) function as activity-dependent autoreceptors, inhibiting transmission in supraspinal sites. These receptors are expressed by peripheral nociceptors. We investigated whether mGluRs function as activity-dependent autoreceptors inhibiting pain transmission to the rat CNS, particularly TRPV1-induced activity. Blocking peripheral mGluR activity by intraplantar injection of antagonists LY341495 (LY, 20, 100 μM, Group II/III ), APICA (100 μM, Group II) or UBP1112 (30 μM, Group III) increased capsaicin (CAP)-induced nociceptive behaviors and nociceptor activity. In contrast, Group II agonist APDC (0.1 μM) or Group III agonist L-AP4 (10 μM) blocked the LY-induced increase. Ca2+ imaging in dorsal root ganglion (DRG) cells confirmed LY enhanced CAP-induced Ca2+ mobilization which was blocked by APDC and L-AP4. We hypothesized that excess glutamate (GLU), released by high intensity and/or prolonged stimulation endogenously activated Group II/III, dampening nociceptor activation. In support of this, intraplantar GLU+LY produced heat hyperalgesia and exogenous GLU+LY applied to nociceptors produced enhanced nociceptor activity and thermal sensitization. Intraplantar formalin known to elevate extracellular GLU, enhanced pain behaviors in the presence of LY. LY alone produced no pain behaviors, no change in nociceptor discharge rate or heat-evoked responses and no change in cytosolic Ca2+ in DRG cells, demonstrating a lack of tonic inhibitory control. Group II/III mGluRs maintain an activity-dependent autoinhibition, capable of significantly reducing TRPV1-induced activity. They are endogenously activated following high frequency and/or prolonged nociceptor stimulation, acting as built-in negative modulators of TRPV1 and nociceptor function, reducing pain transmission to the CNS. PMID:21900552

  4. Intermolecular potential energy surface and thermophysical properties of ethylene oxide

    NASA Astrophysics Data System (ADS)

    Crusius, Johann-Philipp; Hellmann, Robert; Hassel, Egon; Bich, Eckard

    2014-10-01

    A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C2H4O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide.

  5. Intermolecular potential energy surface and thermophysical properties of ethylene oxide

    SciTech Connect

    Crusius, Johann-Philipp Hassel, Egon; Hellmann, Robert; Bich, Eckard

    2014-10-28

    A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C{sub 2}H{sub 4}O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide.

  6. Evidence of active tectonics on a Roman aqueduct system (II-III century A.D.) near Rome, Italy

    NASA Astrophysics Data System (ADS)

    Marra, Fabrizio; Montone, Paola; Pirro, Mario; Boschi, Enzo

    2004-04-01

    In this paper we describe evidence of strong tectonic deformation affecting two aqueducts of Roman age (II-III century A.D.). The channels are located approximately 20 km northeast of Rome along the ancient Via Tiburtina. Brittle and ductile deformation affects these two structures, including extensional joint systems, NE-oriented faults, and horizontal distortion. This deformation is consistent with right-lateral movement on major N-striking faults, and represents the first evidence that tectonic deformation took place in historical times in the vicinity of Rome, with local strike-slip movement superimposed on a regional extensional fault system.

  7. Chitosan-Functionalized Graphene Oxide as a Potential Immunoadjuvant

    PubMed Central

    Yan, Ting; Zhang, Huijie; Huang, Dandi; Feng, Shini; Fujita, Morihisa; Gao, Xiao-Dong

    2017-01-01

    The application of graphene oxide (GO) as a potential vaccine adjuvant has recently attracted considerable attention. However, appropriate surface functionalization of GO is crucial to improve its biocompatibility and enhance its adjuvant activity. In this study, we developed a simple method to prepare chitosan (CS)-functionalized GO (GO-CS) and further investigated its potential as a nanoadjuvant. Compared with GO, GO-CS possessed considerably smaller size, positive surface charge, and better thermal stability. The functionalization of GO with CS was effective in decreasing the non-specific protein adsorption and improving its biocompatibility. Furthermore, GO-CS significantly activated RAW264.7 cells and stimulated more cytokines for mediating cellular immune response, which was mainly due to the synergistic immunostimulatory effect of both GO and CS. GO-CS exhibits strong potential as a safe nanoadjuvant for vaccines and immunotherapy. PMID:28336893

  8. Chitosan-Functionalized Graphene Oxide as a Potential Immunoadjuvant.

    PubMed

    Yan, Ting; Zhang, Huijie; Huang, Dandi; Feng, Shini; Fujita, Morihisa; Gao, Xiao-Dong

    2017-03-08

    The application of graphene oxide (GO) as a potential vaccine adjuvant has recently attracted considerable attention. However, appropriate surface functionalization of GO is crucial to improve its biocompatibility and enhance its adjuvant activity. In this study, we developed a simple method to prepare chitosan (CS)-functionalized GO (GO-CS) and further investigated its potential as a nanoadjuvant. Compared with GO, GO-CS possessed considerably smaller size, positive surface charge, and better thermal stability. The functionalization of GO with CS was effective in decreasing the non-specific protein adsorption and improving its biocompatibility. Furthermore, GO-CS significantly activated RAW264.7 cells and stimulated more cytokines for mediating cellular immune response, which was mainly due to the synergistic immunostimulatory effect of both GO and CS. GO-CS exhibits strong potential as a safe nanoadjuvant for vaccines and immunotherapy.

  9. Two Oxidation Sites for Low Redox Potential Substrates

    PubMed Central

    Morales, María; Mate, María J.; Romero, Antonio; Martínez, María Jesús; Martínez, Ángel T.; Ruiz-Dueñas, Francisco J.

    2012-01-01

    Versatile peroxidase shares with manganese peroxidase and lignin peroxidase the ability to oxidize Mn2+ and high redox potential aromatic compounds, respectively. Moreover, it is also able to oxidize phenols (and low redox potential dyes) at two catalytic sites, as shown by biphasic kinetics. A high efficiency site (with 2,6-dimethoxyphenol and p-hydroquinone catalytic efficiencies of ∼70 and ∼700 s−1 mm−1, respectively) was localized at the same exposed Trp-164 responsible for high redox potential substrate oxidation (as shown by activity loss in the W164S variant). The second site, characterized by low catalytic efficiency (∼3 and ∼50 s−1 mm−1 for 2,6-dimethoxyphenol and p-hydroquinone, respectively) was localized at the main heme access channel. Steady-state and transient-state kinetics for oxidation of phenols and dyes at the latter site were improved when side chains of residues forming the heme channel edge were removed in single and multiple variants. Among them, the E140G/K176G, E140G/P141G/K176G, and E140G/W164S/K176G variants attained catalytic efficiencies for oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) at the heme channel similar to those of the exposed tryptophan site. The heme channel enlargement shown by x-ray diffraction of the E140G, P141G, K176G, and E140G/K176G variants would allow a better substrate accommodation near the heme, as revealed by the up to 26-fold lower Km values (compared with native VP). The resulting interactions were shown by the x-ray structure of the E140G-guaiacol complex, which includes two H-bonds of the substrate with Arg-43 and Pro-139 in the distal heme pocket (at the end of the heme channel) and several hydrophobic interactions with other residues and the heme cofactor. PMID:23071108

  10. Potential disruption of protein-protein interactions by graphene oxide

    NASA Astrophysics Data System (ADS)

    Feng, Mei; Kang, Hongsuk; Yang, Zaixing; Luan, Binquan; Zhou, Ruhong

    2016-06-01

    Graphene oxide (GO) is a promising novel nanomaterial with a wide range of potential biomedical applications due to its many intriguing properties. However, very little research has been conducted to study its possible adverse effects on protein-protein interactions (and thus subsequent toxicity to human). Here, the potential cytotoxicity of GO is investigated at molecular level using large-scale, all-atom molecular dynamics simulations to explore the interaction mechanism between a protein dimer and a GO nanosheet oxidized at different levels. Our theoretical results reveal that GO nanosheet could intercalate between the two monomers of HIV-1 integrase dimer, disrupting the protein-protein interactions and eventually lead to dimer disassociation as graphene does [B. Luan et al., ACS Nano 9(1), 663 (2015)], albeit its insertion process is slower when compared with graphene due to the additional steric and attractive interactions. This study helps to better understand the toxicity of GO to cell functions which could shed light on how to improve its biocompatibility and biosafety for its wide potential biomedical applications.

  11. [Characteristic of inflammatory infiltrate of gastric mucosa in patients with grade II-III gastric dysplasia and of stomach cancer].

    PubMed

    Evtushenko, V A; Vusik, M V; Karakeshisheva, M B; Pleshko, R I; Ermolaeva, L A

    2008-01-01

    The study included 85 inpatients and outpatients in whom composition of inflammatory infiltrate from gastric mucosa (GM) was determined at the Oncological Research Institute, Tomsk Research Centre of the Siberian Division, Russian Academy of Medical Sciences. The patients were allocated to 4 groups depending on nosological form of the disease. Group 1 comprised 21 patients with grade II-III GM epithelial dysplasia, group 2 - 24 patients having stomach cancer (histologically confirmed adenocarcinoma), group 3 - 19 patients with stage II-III mucinous gastric carcinoma, group 4 - 20 allegedly healthy subjects without signs of gastrointestinal pathology. It was shown that dysplastic processes in GM are associated with an increase of neutrophil, eosinophil, macrophage, and mast cell count along with a drop in the number of lymphocytes and plasmocytes. Stroma of invasive stomach cancer underwent intense inflammatory infiltration accompanied by a rise in the number of lymphocytes, plasmocytes, and neutrophils. Mucinous gastric carcinoma was characterized by an increase of the number of neutrophils and macrophages. Patients having adenocarcinoma of the stomach showed enhanced plasmocytic infiltration by plasmocytes with a low number of eosinophils and mast cells. It is concluded that characteristics of inflammatory GM infiltrate may be useful for the objective assessment of stomach cancer risk in patients with GM dysplasia, formation of a high oncological risk group, adequate dynamic monitoring and treatment of these patients.

  12. Prognostic value of tumor infiltrating NK cells and macrophages in stage II+III esophageal cancer patients

    PubMed Central

    Zheng, Xiao; Shi, Liangrong; Wu, Changping; Jiang, Jingting

    2016-01-01

    The detailed understanding of the immunobiology of tumor microenvironment has recently translated into new therapeutic approach against human cancers. Besides the role of immune cells mediating adaptive immune responses, the tumor infiltrating components of the innate immune system including, neutrophils, mast cells, NK cells, and macrophages, also role importantly in anti-tumor immunity. In our present study, we retrospectively analyzed the prognostic value of the densities of tumor infiltrating NK cells and macrophages in esophageal cancer tissues derived from stage II+III patients. Our results showed that the density of the infiltrating NK cells in tumor stroma was significantly associated with nodal status. In addition, the densities of the infiltrating NK cells in tumor nest, and the infiltrating macrophages in tumor nest as well as in tumor stroma, were significantly associated with patients' postoperative prognoses. Furthermore, the combination of infiltrating NK cells in tumor nest and stroma, or the combination of infiltrating macrophages in tumor nest and stroma, could also be used as important prognostic tool in predicting the survival of the stage II+III esophageal cancer patients. PMID:27736796

  13. Magnetic properties of diruthenium(II,III) carboxylate compounds with large zero-field splitting and strong antiferromagnetic coupling.

    PubMed

    Jiménez-Aparicio, R; Urbanos, F A; Arrieta, J M

    2001-02-12

    The magnetic properties of mixed-valent compounds of general formula Ru2Cl(mu-O2CR)4 [R = CH2-CH3 (1), C(Me)=CHEt) (2)] have been studied in the 2-300 K temperature range. This magnetic study also includes a revision of the magnetic properties of the complex Ru2Cl(mu-O2CCMePh2)4 (3). Compounds 1-3 show a linear structure and a strong antiferromagnetic coupling between the diruthenium units through the chlorine atoms according to previous studies. Two fitting models to explain the magnetic properties of these complexes that incorporate a large zero-field splitting together with a strong antiferromagnetic coupling are described. These models consider that each diruthenium unit (S = 3/2) is magnetically coupled to the nearest diruthenium unit and ignores the longer distance magnetic coupling. The fitting models were found to be successful in fitting the magnetic data of the linear diruthenium(II,III) complexes. The zero-field splitting, D, and the antiferromagnetic coupling, zJ, vary from 37.8 to 48.0 cm-1 and from -7.43 to -13.30 cm-1, respectively, for complexes. The D values are similar to those calculated for the nonlinear diruthenium(II,III) compounds and confirm the validity of the proposed fitting models.

  14. Structural determinants for activation or inhibition of ryanodine receptors by basic residues in the dihydropyridine receptor II-III loop.

    PubMed Central

    Casarotto, M G; Green, D; Pace, S M; Curtis, S M; Dulhunty, A F

    2001-01-01

    The structures of peptide A, and six other 7-20 amino acid peptides corresponding to sequences in the A region (Thr671- Leu690) of the skeletal muscle dihydropyridine receptor II-III loop have been examined, and are correlated with the ability of the peptides to activate or inhibit skeletal ryanodine receptor calcium release channels. The peptides adopted either random coil or nascent helix-like structures, which depended upon the polarity of the terminal residues as well as the presence and ionisation state of two glutamate residues. Enhanced activation of Ca2+ release from sarcoplasmic reticulum, and activation of current flow through single ryanodine receptor channels (at -40 mV), was seen with peptides containing the basic residues 681Arg Lys Arg Arg Lys685, and was strongest when the residues were a part of an alpha-helix. Inhibition of channels (at +40 mV) was also seen with peptides containing the five positively charged residues, but was not enhanced in helical peptides. These results confirm the hypothesis that activation of ryanodine receptor channels by the II-III loop peptides requires both the basic residues and their participation in helical structure, and show for the first time that inhibition requires the basic residues, but is not structure-dependent. These findings imply that activation and inhibition result from peptide binding to separate sites on the ryanodine receptor. PMID:11371447

  15. Assessment of Eccentric Exercise-Induced Oxidative Stress Using Oxidation-Reduction Potential Markers

    PubMed Central

    Stagos, Dimitrios; Goutzourelas, Nikolaos; Ntontou, Amalia-Maria; Kafantaris, Ioannis; Deli, Chariklia K.; Poulios, Athanasios; Jamurtas, Athanasios Z.; Bar-Or, David; Kouretas, Dimitrios

    2015-01-01

    The aim of the present study was to investigate the use of static (sORP) and capacity ORP (cORP) oxidation-reduction potential markers as measured by the RedoxSYS Diagnostic System in plasma, for assessing eccentric exercise-induced oxidative stress. Nineteen volunteers performed eccentric exercise with the knee extensors. Blood was collected before, immediately after exercise, and 24, 48, and 72 h after exercise. Moreover, common redox biomarkers were measured, which were protein carbonyls, thiobarbituric acid-reactive substances, total antioxidant capacity in plasma, and catalase activity and glutathione levels in erythrocytes. When the participants were examined as one group, there were not significant differences in any marker after exercise. However, in 11 participants there was a high increase in cORP after exercise, while in 8 participants there was a high decrease. Thus, the participants were divided in low cORP group exhibiting significant decrease in cORP after exercise and in high cORP group exhibiting significant increase. Moreover, only in the low cORP group there was a significant increase in lipid peroxidation after exercise suggesting induction of oxidative stress. The results suggested that high decreases in cORP values after exercise may indicate induction of oxidative stress by eccentric exercise, while high increases in cORP values after exercise may indicate no existence of oxidative stress. PMID:25874019

  16. Assessment of eccentric exercise-induced oxidative stress using oxidation-reduction potential markers.

    PubMed

    Stagos, Dimitrios; Goutzourelas, Nikolaos; Ntontou, Amalia-Maria; Kafantaris, Ioannis; Deli, Chariklia K; Poulios, Athanasios; Jamurtas, Athanasios Z; Bar-Or, David; Kouretas, Dimitrios

    2015-01-01

    The aim of the present study was to investigate the use of static (sORP) and capacity ORP (cORP) oxidation-reduction potential markers as measured by the RedoxSYS Diagnostic System in plasma, for assessing eccentric exercise-induced oxidative stress. Nineteen volunteers performed eccentric exercise with the knee extensors. Blood was collected before, immediately after exercise, and 24, 48, and 72 h after exercise. Moreover, common redox biomarkers were measured, which were protein carbonyls, thiobarbituric acid-reactive substances, total antioxidant capacity in plasma, and catalase activity and glutathione levels in erythrocytes. When the participants were examined as one group, there were not significant differences in any marker after exercise. However, in 11 participants there was a high increase in cORP after exercise, while in 8 participants there was a high decrease. Thus, the participants were divided in low cORP group exhibiting significant decrease in cORP after exercise and in high cORP group exhibiting significant increase. Moreover, only in the low cORP group there was a significant increase in lipid peroxidation after exercise suggesting induction of oxidative stress. The results suggested that high decreases in cORP values after exercise may indicate induction of oxidative stress by eccentric exercise, while high increases in cORP values after exercise may indicate no existence of oxidative stress.

  17. Global Change Simulations Affect Potential Methane Oxidation in Upland Soils

    NASA Astrophysics Data System (ADS)

    Blankinship, J. C.; Hungate, B. A.

    2004-12-01

    Atmospheric concentrations of methane (CH4) are higher now than they have ever been during the past 420,000 years. However, concentrations have remained stable since 1999. Emissions associated with livestock husbandry are unlikely to have changed, so some combination of reduced production in wetlands, more efficient capture by landfills, or increased consumption by biological CH4 oxidation in upland soils may be responsible. Methane oxidizing bacteria are ubiquitous in upland soils and little is known about how these bacteria respond to anthropogenic global change, and how they will influence - or already are influencing - the radiative balance of the atmosphere. Might ongoing and future global changes increase biological CH4 oxidation? Soils were sampled from two field experiments to assess changes in rates of CH4 oxidation in response to global change simulations. Potential activities of CH4 oxidizing bacterial communities were measured through laboratory incubations under optimal temperature, soil moisture, and atmospheric CH4 concentrations (~18 ppm, or 10x ambient). The ongoing 6-year multifactorial Jasper Ridge Global Change Experiment (JRGCE) simulates warming, elevated precipitation, elevated atmospheric CO2, elevated atmospheric N deposition, and increased wildfire frequency in an annual grassland in a Mediterranean-type climate in central California. The ongoing 1-year multifactorial Merriam Climate Change Experiment (MCCE) simulates warming, elevated precipitation, and reduced precipitation in four different types of ecosystems along an elevational gradient in a semi-arid climate in northern Arizona. The high desert grassland, pinyon-juniper woodland, ponderosa pine forest, and mixed conifer forest ecosystems range in annual precipitation from 100 to 1000 mm yr-1, and from productivity being strongly water limited to strongly temperature limited. Among JRGCE soils, elevated atmospheric CO2 increased potential CH4 oxidation rates (p=0.052) and wildfire

  18. Oxidative shift in tissue redox potential increases beat-to-beat variability of action potential duration.

    PubMed

    Kistamás, Kornél; Hegyi, Bence; Váczi, Krisztina; Horváth, Balázs; Bányász, Tamás; Magyar, János; Szentandrássy, Norbert; Nánási, Péter P

    2015-07-01

    Profound changes in tissue redox potential occur in the heart under conditions of oxidative stress frequently associated with cardiac arrhythmias. Since beat-to-beat variability (short term variability, SV) of action potential duration (APD) is a good indicator of arrhythmia incidence, the aim of this work was to study the influence of redox changes on SV in isolated canine ventricular cardiomyocytes using a conventional microelectrode technique. The redox potential was shifted toward a reduced state using a reductive cocktail (containing dithiothreitol, glutathione, and ascorbic acid) while oxidative changes were initiated by superfusion with H2O2. Redox effects were evaluated as changes in "relative SV" determined by comparing SV changes with the concomitant APD changes. Exposure of myocytes to the reductive cocktail decreased SV significantly without any detectable effect on APD. Application of H2O2 increased both SV and APD, but the enhancement of SV was the greater, so relative SV increased. Longer exposure to H2O2 resulted in the development of early afterdepolarizations accompanied by tremendously increased SV. Pretreatment with the reductive cocktail prevented both elevation in relative SV and the development of afterdepolarizations. The results suggest that the increased beat-to-beat variability during an oxidative stress contributes to the generation of cardiac arrhythmias.

  19. Detection of methicillin-resistant Staphylococcus pseudintermedius ST169 and novel ST354 SCCmec II-III isolates related to the worldwide ST71 clone.

    PubMed

    Ishihara, K; Koizumi, A; Saito, M; Muramatsu, Y; Tamura, Y

    2016-01-01

    The recent appearance of methicillin-resistant Staphylococcus pseudintermedius (MRSP) is a concern for both veterinary and human healthcare. MRSP clonal lineages with sequence type (ST) 71-spa t02-staphylococcal cassette chromosome mec (SCCmec) II-III and ST68-spa t06-SCCmec V have spread throughout Europe and North America, respectively. The current study compared the molecular characteristics of 43 MRSP isolates from dogs in Japan with those of MRSP from previous reports using multilocus sequence typing based on seven housekeeping genes, SCCmec typing, and detection of antimicrobial resistance genes. Three related clonal lineages, ST71, ST169, and the newly registered ST354, were observed in SCCmec II-III isolates from Japan, despite MRSP SCCmec II-III isolates being thought to belong to a single clonal lineage. The majority of SCCmec II-III isolates belonging to ST169 (9/11) and ST354 (3/3), but not ST71 (0/11), harboured tetM. Four STs were observed for the SCCmec V isolates; however, neither ST68 nor related STs were found in the Japanese MRSP isolates. In conclusion, MRSP SCCmec II-III isolates from Japan belonged to ST71 and related STs (ST169 and ST354). A variety of MRSP SCCmec V clones, including some novel clones, were identified.

  20. Effect of Postmastectomy Radiotherapy in Patients <35 Years Old With Stage II-III Breast Cancer Treated With Doxorubicin-Based Neoadjuvant Chemotherapy and Mastectomy

    SciTech Connect

    Garg, Amit K.; Oh, Julia L. Oswald, Mary Jane; Huang, Eugene; Strom, Eric A.; Perkins, George H.; Woodward, Wendy A.; Yu, T. Kuan; Tereffe, Welela; Meric-Bernstam, Funda; Hahn, Karin; Buchholz, Thomas A.

    2007-12-01

    Purpose: Postmastectomy radiotherapy (PMRT) improves locoregional control (LRC) in patients with high-risk features after mastectomy. Young age continues to evolve as a potentially important risk factor. The objective of this study was to assess the benefits of PMRT in patients <35 years old treated with doxorubicin-based neoadjuvant chemotherapy for Stage II-III breast cancer. Patients and Methods: We retrospectively analyzed 107 consecutive breast cancer patients <35 years old with Stage IIA-IIIC disease treated at our institution with doxorubicin-based neoadjuvant chemotherapy and mastectomy, with or without PMRT. The treatment groups were compared in terms of LRC and overall survival. Results: Despite more advanced disease stages, the patients who received PMRT (n = 80) had greater rates of LRC (5-year rate, 88% vs. 63%, p = 0.001) and better overall survival (5-year rate, 67% vs. 48%, p = 0.03) than patients who did not receive PMRT (n = 27). Conclusion: Among breast cancer patients <35 years old at diagnosis, the use of PMRT after doxorubicin-based neoadjuvant chemotherapy and mastectomy led to a statistically greater rate of LRC and overall survival compared with patients without PMRT. The benefit seen for PMRT in young patients provides valuable data to better tailor adjuvant, age-specific treatment decisions after mastectomy.

  1. Valproic Acid, a Histone Deacetylase Inhibitor, in Combination with Paclitaxel for Anaplastic Thyroid Cancer: Results of a Multicenter Randomized Controlled Phase II/III Trial

    PubMed Central

    Pugliese, Mariateresa; Gallo, Marco; Brignardello, Enrico; Milla, Paola; Orlandi, Fabio; Limone, Paolo Piero; Arvat, Emanuela; Boccuzzi, Giuseppe; Piovesan, Alessandro

    2016-01-01

    Anaplastic thyroid cancer (ATC) has a median survival less than 5 months and, to date, no effective therapy exists. Taxanes have recently been stated as the main drug treatment for ATC, and the histone deacetylase inhibitor valproic acid efficiently potentiates the effects of paclitaxel in vitro. Based on these data, this trial assessed the efficacy and safety of the combination of paclitaxel and valproic acid for the treatment of ATC. This was a randomized, controlled phase II/III trial, performed on 25 ATC patients across 5 centers in northwest Italy. The experimental arm received the combination of paclitaxel (80 mg/m2/weekly) and valproic acid (1,000 mg/day); the control arm received paclitaxel alone. Overall survival and disease progression, evaluated in terms of progression-free survival, were the primary outcomes. The secondary outcome was the pharmacokinetics of paclitaxel. The coadministration of valproic acid did not influence the pharmacokinetics of paclitaxel. Neither median survival nor median time to progression was statistically different in the two arms. Median survival of operated-on patients was significantly better than that of patients who were not operated on. The present trial demonstrates that the addition of valproic acid to paclitaxel has no effect on overall survival and disease progression of ATC patients. This trial is registered with EudraCT 2008-005221-11. PMID:27766105

  2. Racial and Socioeconomic Treatment Disparities in Adolescents and Young Adults with Stage II-III Rectal Cancer.

    PubMed

    Lee, David Y; Teng, Annabelle; Pedersen, Rose C; Tavangari, Farees R; Attaluri, Vikram; McLemore, Elisabeth C; Stern, Stacey L; Bilchik, Anton J; Goldfarb, Melanie R

    2017-02-01

    Stage II-III rectal cancer requires multidisciplinary cancer care, and adolescents and young adults (AYA, ages 15-39 years) often do not receive optimal cancer therapy. Overall, 3295 AYAs with clinical stage II-III rectal cancer were identified in the National Cancer Database. Factors associated with the receipt of adjuvant and surgical therapies, as well as overall survival (OS), were examined. The majority of patients were non-Hispanic White (72.0 %), male (57.5 %), and without comorbidities (93.8 %). A greater proportion of Black and Hispanic patients did not receive radiation (24.5 and 27.1 %, respectively, vs. 16.5 % for non-Hispanic White patients), surgery (22.4 % and 21.6 vs. 12.3 %), or chemotherapy (21.5 % and 24.1 vs. 14.7 %) compared with non-Hispanic White patients (all p < 0.05). After controlling for competing factors, Black (odds ratio [OR] 0.7, 95 % confidence interval [CI] 0.5-0.9) and Hispanic patients (OR 0.6, 95 % CI 0.4-0.9) were less likely to receive neoadjuvant chemoradiation compared with non-Hispanic White patients. Females, the uninsured, and those treated at a community cancer center were also less likely to receive neoadjuvant therapy. Having government insurance (OR 0.22, 95 % CI 010-0.49) was a predictor for not receiving surgery. Although 5-year OS was lower (p < 0.05) in Black (59.8 %) and Hispanic patients (65.9 %) compared with non-Hispanic White patients (74.9 %), on multivariate analysis race did not impact mortality. Not having surgery (hazard ratio [HR] 7.1, 95 % CI 2.8-18.2) had the greatest influence on mortality, followed by poorly differentiated histology (HR 3.0, 95 % CI 1.3-6.5), nodal positivity (HR 2.6, 95 % CI 1.9-3.6), no chemotherapy (HR 1.9, 95 % CI 1.03-3.6), no insurance (HR 1.7, 95 % CI 1.1-2.7), and male sex (HR 1.5, 95 % CI 1.1-2.0). There are racial and socioeconomic disparities in the treatment of stage II-III rectal cancer in AYAs, many of which impact OS. Interventions that can

  3. Henna: a potential cause of oxidative hemolysis and neonatal hyperbilirubinemia.

    PubMed

    Zinkham, W H; Oski, F A

    1996-05-01

    To evaluate the in vitro oxidation potential of lawsone (2-hydroxy-1,4 naphthoquinone). Lawsone is a chemical present in henna, the crushed leaves of which are used worldwide as a cosmetic agent to stain the hair, skin, and nails. Venous blood from glucose-6-phosphate dehydrogenase (G6PD)-normal and G6PD A- subjects were incubated with various amounts of lawsone for 2 hours at 37 degrees C. Reduced glutathione and methemoglobin (MHb) levels were measured before and after incubation. Final molar concentrations of lawsone in normal blood of 1.4, 2.8, 5.7, and 8.6 x 10-3 mol/L increased MHb percentages from 0.5% to 2.2%, 8.3%, 9.5% and 12.5%, respectively. In a C6PD A- blood, MHb percentages were 19.8%, 32.2%, 44.9%, and 53.9%. At a lawsone concentration of 2.8 x 10-3 mol/L, blood from 15 healthy adults formed MHb percentages of 7.4% +/- 3.3% (+/- 1 SD); in blood from 4 G6PD A- adults, percentages were 44.5%, 40.6%, 41.3%, and 42.8%. Simultaneous measurements of reduced glutathione revealed preincubation values of greater than 40 mg/100 mL of red cells in blood of healthy and G6PD A- subjects. Postincubation values were greater than 40 in blood of healthy subjects and less than 40 in blood of G6PD A- subjects. These in vitro observations indicate that lawsone is an agent capable of causing oxidative hemolysis. In regions of the world where there is a high incidence of G6PD deficiency and unexplained hyperbilirubinemia, oxidative hemolysis secondary to the cutaneous application of henna could be the initiating event.

  4. Oxidative Stress in COPD: Sources, Markers, and Potential Mechanisms

    PubMed Central

    McGuinness, Adam John Anthony; Sapey, Elizabeth

    2017-01-01

    Markers of oxidative stress are increased in chronic obstructive pulmonary disease (COPD) and reactive oxygen species (ROS) are able to alter biological molecules, signaling pathways and antioxidant molecule function, many of which have been implicated in the pathogenesis of COPD. However, the involvement of ROS in the development and progression of COPD is not proven. Here, we discuss the sources of ROS, and the defences that have evolved to protect against their harmful effects. We address the role that ROS may have in the development and progression of COPD, as well as current therapeutic attempts at limiting the damage they cause. Evidence has indicated that the function of several key cells appears altered in COPD patients, and expression levels of important oxidant and antioxidant molecules may be abnormal. Therapeutic trials attempting to restore equilibrium to these molecules have not impacted upon all facets of disease and whilst the theory behind ROS influence in COPD appears sound, current models testing relevant pathways to tissue damage are limited. The heterogeneity seen in COPD patients presents a challenge to our understanding, and further research is essential to identify potential targets and stratified COPD patient populations where ROS therapies may be maximally efficacious. PMID:28212273

  5. Potential use and perspectives of nitric oxide donors in agriculture.

    PubMed

    Marvasi, Massimiliano

    2017-03-01

    Nitric oxide (NO) has emerged in the last 30 years as a key molecule involved in many physiological processes in plants, animals and bacteria. Current research has shown that NO can be delivered via donor molecules. In such cases, the NO release rate is dependent on the chemical structure of the donor itself and on the chemical environment. Despite NO's powerful signaling effect in plants and animals, the application of NO donors in agriculture is currently not implemented and research remains mainly at the experimental level. Technological development in the field of NO donors is rapidly expanding in scope to include controlling seed germination, plant development, ripening and increasing shelf-life of produce. Potential applications in animal production have also been identified. This concise review focuses on the use of donors that have shown potential biotechnological applications in agriculture. Insights are provided into (i) the role of donors in plant production, (ii) the potential use of donors in animal production and (iii) future approaches to explore the use and applications of donors for the benefit of agriculture. © 2016 Society of Chemical Industry.

  6. Genotoxic and oxidative stress potential of nanosized and bulk zinc oxide particles in Drosophila melanogaster.

    PubMed

    Carmona, Erico R; Inostroza-Blancheteau, Claudio; Rubio, Laura; Marcos, Ricard

    2016-12-01

    Zinc oxide nanoparticles (ZnONP) are manufactured on a large scale and can be found in a variety of consumer products, such as sunscreens, lotions, paints and food additives. Few studies have been carried out on its genotoxic potential and related mechanisms in whole organisms. In the present study, the in vivo genotoxic activity of ZnONP and its bulk form was assayed using the wing-spot test and comet assay in Drosophila melanogaster Additionally, a lipid peroxidation analysis using the thiobarbituric acid assay was also performed. Results obtained with the wing-spot test showed a lack of genotoxic activity of both ZnO forms. However, when both particle sizes were tested in the comet assay using larvae haemocytes, a significant increase in DNA damage was observed for ZnONP treatments but only at the higher dose applied. In addition, the lipid peroxidation assay showed significant malondialdehyde (MDA) induction for both ZnO forms, but the induction of MDA for ZnONP was higher for the ZnO bulk, suggesting that the observed DNA strand breaks could be induced by mediated oxidative stress. The overall data suggest that the potential genotoxicity of ZnONP in Drosophila can be considered weak according to the lack of mutagenic and recombinogenic effects and the induction of primary DNA damage only at high toxic doses of ZnONP. This study is the first assessing the genotoxic and oxidative stress potential of nano and bulk ZnO particles in Drosophila. © The Author(s) 2015.

  7. Molecular basis of multiple sulfatase deficiency, mucolipidosis II/III and Niemann-Pick C1 disease - Lysosomal storage disorders caused by defects of non-lysosomal proteins.

    PubMed

    Dierks, Thomas; Schlotawa, Lars; Frese, Marc-André; Radhakrishnan, Karthikeyan; von Figura, Kurt; Schmidt, Bernhard

    2009-04-01

    Multiple sulfatase deficiency (MSD), mucolipidosis (ML) II/III and Niemann-Pick type C1 (NPC1) disease are rare but fatal lysosomal storage disorders caused by the genetic defect of non-lysosomal proteins. The NPC1 protein mainly localizes to late endosomes and is essential for cholesterol redistribution from endocytosed LDL to cellular membranes. NPC1 deficiency leads to lysosomal accumulation of a broad range of lipids. The precise functional mechanism of this membrane protein, however, remains puzzling. ML II, also termed I cell disease, and the less severe ML III result from deficiencies of the Golgi enzyme N-acetylglucosamine 1-phosphotransferase leading to a global defect of lysosome biogenesis. In patient cells, newly synthesized lysosomal proteins are not equipped with the critical lysosomal trafficking marker mannose 6-phosphate, thus escaping from lysosomal sorting at the trans Golgi network. MSD affects the entire sulfatase family, at least seven members of which are lysosomal enzymes that are specifically involved in the degradation of sulfated glycosaminoglycans, sulfolipids or other sulfated molecules. The combined deficiencies of all sulfatases result from a defective post-translational modification by the ER-localized formylglycine-generating enzyme (FGE), which oxidizes a specific cysteine residue to formylglycine, the catalytic residue enabling a unique mechanism of sulfate ester hydrolysis. This review gives an update on the molecular bases of these enigmatic diseases, which have been challenging researchers since many decades and so far led to a number of surprising findings that give deeper insight into both the cell biology and the pathobiochemistry underlying these complex disorders. In case of MSD, considerable progress has been made in recent years towards an understanding of disease-causing FGE mutations. First approaches to link molecular parameters with clinical manifestation have been described and even therapeutical options have been

  8. Gadolinium oxide nanoparticles as potential multimodal imaging and therapeutic agents.

    PubMed

    Kim, Tae Jeong; Chae, Kwon Seok; Chang, Yongmin; Lee, Gang Ho

    2013-01-01

    Potentials of hydrophilic and biocompatible ligand coated gadolinium oxide nanoparticles as multimodal imaging agents, drug carriers, and therapeutic agents are reviewed. First of all, they can be used as advanced T1 magnetic resonance imaging (MRI) contrast agents because they have r1 larger than those of Gd(III)-chelates due to a high density of Gd(III) per nanoparticle. They can be further functionalized by conjugating other imaging agents such as fluorescent imaging (FI), X-ray computed tomography (CT), positron emission tomography (PET), and single photon emission tomography (SPECT) agents. They can be also useful for drug carriers through morphology modifications. They themselves are also potential CT and ultrasound imaging (USI) contrast and thermal neutron capture therapeutic (NCT) agents, which are superior to commercial iodine compounds, air-filled albumin microspheres, and boron ((10)B) compounds, respectively. They, when conjugated with targeting agents such as antibodies and peptides, will provide enhanced images and be also very useful for diagnosis and therapy of diseases (so called theragnosis).

  9. Pro-oxidant and antioxidant potential of catecholestrogens against ferrylmyoglobin-induced oxidative stress.

    PubMed

    Martínez, Rosa; Quintana, Kristina; Navarro, Rosaura; Martín, César; Hernández, M Luisa; Aurrekoetxea, Igor; Ruiz-Sanz, José Ignacio; Lacort, Mercedes; Ruiz-Larrea, M Begoña

    2002-07-11

    Ferryl heme proteins may play a major role in vivo under certain pathological conditions. Catecholestrogens, the estradiol-derived metabolites, can act either as antioxidants or pro-oxidants in iron-dependent systems. The aim of the present work was (1) to determine the effects of ferrylmyoglobin on hepatocyte cytotoxicity, and (2) to assess the pro/antioxidant potential of a series of estrogens (phenolic, catecholic and stilbene-derived) against ferrylmyoglobin induced lipid peroxidation in rat hepatocytes. Cells were exposed to metmyoglobin plus hydrogen peroxide to form ferrylmyoglobin in the presence of the transition metal chelator diethylentriaminepentaacetic acid. Results showed that ferrylmyoglobin induced an initial oxidative stress, mainly reflected in an early lipid peroxidation and further decrease in GSH and ATP. However, cells gradually adapted to this situation, by recovering the endogenous ATP and GSH levels at longer incubation times. Phenolic and stilbene-derived estrogens inhibited ferrylmyoglobin-induced lipid peroxidation to different degrees: diethylstilbestrol>estradiol>resveratrol. Catecholestrogens at concentrations higher than 1 microM also inhibited lipid peroxidation with similar efficacy. The ability of estrogens to reduce ferrylmyoglobin to metmyoglobin may account for their antioxidant activity. In contrast, physiological concentrations (100 pM-100 nM) of the catecholestrogens exerted pro-oxidant activities, 4-hydroxyestradiol being more potent than 2-hydroxyestradiol. The implications of these interactions should be considered in situations where local myoglobin or hemoglobin microbleeding takes place.

  10. Modeling Exposures to the Oxidative Potential of PM10

    PubMed Central

    2012-01-01

    Differences in the toxicity of ambient particulate matter (PM) due to varying particle composition across locations may contribute to variability in results from air pollution epidemiologic studies. Though most studies have used PM mass concentration as the exposure metric, an alternative which accounts for particle toxicity due to varying particle composition may better elucidate whether PM from specific sources is responsible for observed health effects. The oxidative potential (OP) of PM < 10 μm (PM10) was measured as the rate of depletion of the antioxidant reduced glutathione (GSH) in a model of human respiratory tract lining fluid. Using a database of GSH OP measures collected in greater London, U.K. from 2002 to 2006, we developed and validated a predictive spatiotemporal model of the weekly GSH OP of PM10 that included geographic predictors. Predicted levels of OP were then used in combination with those of weekly PM10 mass to estimate exposure to PM10 weighted by its OP. Using cross-validation (CV), brake and tire wear emissions of PM10 from traffic within 50 m and tailpipe emissions of nitrogen oxides from heavy-goods vehicles within 100 m were important predictors of GSH OP levels. Predictive accuracy of the models was high for PM10 (CV R2=0.83) but only moderate for GSH OP (CV R2 = 0.44) when comparing weekly levels; however, the GSH OP model predicted spatial trends well (spatial CV R2 = 0.73). Results suggest that PM10 emitted from traffic sources, specifically brake and tire wear, has a higher OP than that from other sources, and that this effect is very local, occurring within 50–100 m of roadways. PMID:22731499

  11. A comparative study of nitrite reduction by synthetic and biogenic Fe(II-III) hydroxysalts green rusts: Evidence for hydroxyl-nitrite green rust formation as an intermediate reaction product.

    NASA Astrophysics Data System (ADS)

    Ona-Nguema, G.; Guerbois, D.; Morin, G.; Zhang, Y.; Noel, V.; Brest, J.

    2013-12-01

    The occurrence of high nitrite concentrations as a result of anthropogenic activities is an important water quality concern as it is highly toxic to human and fauna, and it is used as a nitrogen source for the assimilation process. The toxicity of nitrite is related to its transformation into carcinogenic N-nitroso compounds, which are suspected to be responsible for some gastric cancers, and to its ability to convert the hemoglobin to methaemoglobin what is then unable to fix oxygen and to transport it to the tissues, involving hypoxia and the blue-baby syndrome [1]. To reduce the adverse effect of nitrite on human health and on macroalgal blooms, any process enhancing the transformation of nitrite ions to nitrogen gas is of interest for the remediation of natural environments. To achieve this purpose the use of processes involving Fe(II)-containing minerals could be considered as one of the best options. Green-rusts are mixed Fe(II-III) layered double hydroxides commonly found in anoxic zones of natural environments such as sediments and hydromorphic soils. In such anoxic environments, green rust minerals play an important role in the biogeochemical redox cycling of iron and nitrogen, and can affect the speciation and mobility of many organic and inorganic contaminants. The present study investigates the reduction of nitrite by two synthetic and two biogenic green rusts. On the one hand, Fe(II-III) hydroxychloride and Fe(II-III) hydroxycarbonate green rusts were used as synthetic interlayer forms of GR, which are referred to as ';syn-GR(CO3)' and ';syn-GR(Cl)', respectively. On the other hand, the study was performed with biogenic Fe(II-III) hydroxycarbonate green rusts obtained from the bioreduction of two ferric precursors, either Fe(III)-oxyhydroxycarbonate or lepidocrocite; these biogenic green rusts are referred to as ';bio-GR(CO3)F' and ';bio-GR(CO3)L', respectively. For synthetic green rusts, results showed that the oxidation of both syn-GR(CO3) and syn

  12. Contributions of Kv7-mediated potassium current to sub- and suprathreshold responses of rat layer II/III neocortical pyramidal neurons

    PubMed Central

    Guan, D.; Higgs, M. H.; Horton, L. R.; Spain, W. J.

    2011-01-01

    After block of Kv1- and Kv2-mediated K+ currents in acutely dissociated neocortical pyramidal neurons from layers II/III of rat somatosensory and motor cortex, the remaining current is slowly activating and persistent. We used whole cell voltage clamp to show that the Kv7 blockers linopirdine and XE-991 blocked a current with similar kinetics to the current remaining after combined block of Kv1 and Kv2 channels. This current was sensitive to low doses of linopirdine and activated more slowly and at more negative potentials than Kv1- or Kv2-mediated current. The Kv7-mediated current decreased in amplitude with time in whole cell recordings, but in most cells the current was stable for several minutes. Current in response to a traditional M-current protocol was blocked by muscarine, linopirdine, and XE-991. Whole cell slice recordings revealed that the Q10 for channel deactivation was ∼2.5. Sharp electrode current-clamp recordings from adult pyramidal cells demonstrated that block of Kv7-mediated current with XE-991 reduced rheobase, shortened the latency to firing to near rheobase current, induced more regular firing at low current intensity, and increased the rate of firing to a given current injection. XE-991 did not affect single action potentials or spike frequency adaptation. Application of XE-991 also eliminated subthreshold voltage oscillations and increased gain for low-frequency inputs (<10 Hz) without affecting gain for higher frequency inputs. These data suggest important roles for Kv7 channels in subthreshold regulation of excitability, generation of theta-frequency subthreshold oscillations, regulation of interspike intervals, and biasing selectivity toward higher frequency inputs. PMID:21697446

  13. Oxidative Potential of ambient particulate matter in Athens, Greece.

    NASA Astrophysics Data System (ADS)

    Paraskevopoulou, Despina; Bougiatioti, Aikaterini; Fang, Ting; Liakakou, Eleni; Weber, Rodney; Nenes, Athanasios; Mihalopoulos, Nikolaos

    2017-04-01

    Exposure of populations to airborne particulate matter (PM) is a leading cause of premature death worldwide. Oxidative stress resulting from exposure of chemical species present in PM is a mechanism thought to cause adverse health effects. Apart from radicals present in aerosol, species that can catalytically deplete the antioxidant buffering capacity of cells, called Oxidative Potential (OP), are thought to be particularly toxic. The variability of OP over location, particle age, source and environmental conditions is virtually unknown for most populated regions of the world. Motivated by this, we have built and deployed one of the first operational measurements of OP in Europe at the National Observatory of Athens site in downtown Athens, Greece. OP for fine and coarse mode is measured using a semi-automated dithiothreitol (DTT) assay developed at the Georgia Institute of Technology; the assay measures the oxidation rate of DTT by water-soluble aerosol constituents, and simulates the rate at which the same compounds would deplete antioxidants in-vivo. The DTT oxidation rate per unit volume of air (water-soluble "DTT activity") and aerosol size class (fine, coarse) are used as a measure of aerosol toxicity. We present continuous (24hr average) OP measurements in downtown Athens from July 2016 to January 2017, conducted through quartz fiber filter analysis. The dataset covers a broad range of aerosol sources (pollution from Europe, regional and local biomass burning, dust, marine aerosol, biogenic aerosol) and meteorological conditions. The daily water-soluble DTT activity ranges between 0.02-0.81 nmolmin-1 m-3 (averaging at 0.24 nmolmin-1 m-3) for fine aerosol and between 0.01-0.52 nmolmin-1 m-3 (averaging at 0.08 nmolmin-1 m-3) for coarse particulate matter, indicating that water-soluble fine mode aerosol components possess a significant fraction of the OP. The seasonal variability demonstrates a higher DTT activity during the coldest period of the year for both

  14. Potential Nitrous Oxide Emissions from Municipal Drinking Water

    NASA Astrophysics Data System (ADS)

    Anderson, D. E.; Thienelt, T.; Tindall, J.; McMahon, P.

    2005-12-01

    Nitrous oxide (N2O) is a potent greenhouse gas, having a global warming potential 280 times larger than carbon dioxide. Although the bulk of N2O emissions appear to be related to agricultural activity, various industrial and transportation related emissions exist as well. This study reports the discovery of a new and significant source of potential N2O emissions related to its presence in purified municipal water supplies worldwide. Multiple drinking water samples were obtained from 86 cities in the United States (US) and 44 cities in 16 countries in the Americas, Europe, Asia, and Africa. Samples ranged from 0.004 to 2μmol/L or the equivalent of 60% unsaturated to 200 times supersaturated with respect to ambient atmospheric concentration (320 ppb). Highest N2O contents were from southern US cities. Suspecting nitrification as the cause for the presence of N2O in drinking water, correlation statistics were calculated between N2O concentration and city size, geographical location, mean annual temperature, nitrate, and ammonia concentrations for the total population of samples as well as subsets based on country, water purification method, and raw water source (ground, surface, combination). The highest correlation (r=0.66, p<0.05, N=73) found was between latitude and N2O content for the subset group of large US cities using chloramines to purify water. Continuous year long sampling from a major US city indicated that variance in N2O content is remarkably low through the year within a water supply district. The annual US emission, based on this preliminary analysis, is 8x106 moles or 3.5X108 g N2O. Annual global emissions may be five times larger.

  15. Zeta potentials in the flotation of oxide and silicate minerals.

    PubMed

    Fuerstenau, D W; Pradip

    2005-06-30

    Adsorption of collectors and modifying reagents in the flotation of oxide and silicate minerals is controlled by the electrical double layer at the mineral-water interface. In systems where the collector is physically adsorbed, flotation with anionic or cationic collectors depends on the mineral surface being charged oppositely. Adjusting the pH of the system can enhance or prevent the flotation of a mineral. Thus, the point of zero charge (PZC) of the mineral is the most important property of a mineral in such systems. The length of the hydrocarbon chain of the collector is important because of chain-chain association enhances the adsorption once the surfactant ions aggregate to form hemimicelles at the surface. Strongly chemisorbing collectors are able to induce flotation even when collector and the mineral surface are charged similarly, but raising the pH sufficiently above the PZC can repel chemisorbing collectors from the mineral surface. Zeta potentials can be used to delineate interfacial phenomena in these various systems.

  16. An epidemiological study of workers potentially exposed to ethylene oxide.

    PubMed

    Wong, O; Trent, L S

    1993-04-01

    This epidemiological study was of 18,728 employees at 14 United States facilities producing sterilised medical supplies and spices, who were potentially exposed to ethylene oxide (EO) for at least 90 days. The mortality of the cohort was studied to the end of 1988. A total of 1353 deaths was identified. The cohort had a significantly lower mortality than the general population from all causes, all cancers, and non-malignant diseases. In the entire cohort, mortality was not significantly increased from any of the cancer sites examined. In particular, no significant increase in mortality was found in the cancer sites of interest based on previous studies--namely, stomach, leukaemia (including major specific cell types), pancreas, and brain. The lack of an increased mortality for these cancer sites was further strengthened by the lack of a dose-response relation with duration of employment and latency. Among the men, a statistically significant increase in mortality from non-Hodgkin's lymphoma was found. There was no indication for a dose-response relation for non-Hodgkin's lymphoma and no specific job categories seemed to be responsible for the increase. Among the women, a deficit of non-Hodgkin's lymphoma was found, which was not consistent with the finding in the men. Therefore, the increase among the men did not seem to be related to exposure to EO.

  17. An epidemiological study of workers potentially exposed to ethylene oxide.

    PubMed Central

    Wong, O; Trent, L S

    1993-01-01

    This epidemiological study was of 18,728 employees at 14 United States facilities producing sterilised medical supplies and spices, who were potentially exposed to ethylene oxide (EO) for at least 90 days. The mortality of the cohort was studied to the end of 1988. A total of 1353 deaths was identified. The cohort had a significantly lower mortality than the general population from all causes, all cancers, and non-malignant diseases. In the entire cohort, mortality was not significantly increased from any of the cancer sites examined. In particular, no significant increase in mortality was found in the cancer sites of interest based on previous studies--namely, stomach, leukaemia (including major specific cell types), pancreas, and brain. The lack of an increased mortality for these cancer sites was further strengthened by the lack of a dose-response relation with duration of employment and latency. Among the men, a statistically significant increase in mortality from non-Hodgkin's lymphoma was found. There was no indication for a dose-response relation for non-Hodgkin's lymphoma and no specific job categories seemed to be responsible for the increase. Among the women, a deficit of non-Hodgkin's lymphoma was found, which was not consistent with the finding in the men. Therefore, the increase among the men did not seem to be related to exposure to EO. PMID:8494770

  18. A synthetic leaf: the biomimetic potential of graphene oxide

    NASA Astrophysics Data System (ADS)

    Lamb, Marilla; Koch, George W.; Morgan, Eric R.; Shafer, Michael W.

    2015-03-01

    Emerging materials such as graphene oxide (GO) have micro and nano features that are functionally similar to those in plant cell walls involved in water transport. Therefore, it may now be possible to design and build biomimetic trees to lift water via mechanisms similar to those employed by trees, allowing for potential applications such as passive water pumping, filtering, and evaporative cooling. The tallest trees can raise large volumes of water to over 100 meters using only the vapor pressure gradient between their leaves and the atmosphere. This phenomenon occurs in all terrestrial plants when capillary forces generated in the microscopic pores in the cell walls of leaves are collectively applied to large diameter xylem conduits. The design of a synthetic tree that mimics these mechanisms will allow water to be moved to heights greater than is currently possible by any engineered system that does not require the use of a positive pressure pump. We are testing the suitability of membranous GO as the leaf of a synthetic tree and present an analysis in support of this design. In addition, we include results from a preliminary design using ceramics.

  19. Electrostatic potentials for metal-oxide surfaces and interfaces

    NASA Astrophysics Data System (ADS)

    Streitz, F. H.; Mintmire, J. W.

    1994-10-01

    As most technologically important metals will form oxides readily, any complete study of adhesion at real metal surfaces must include the metal-oxide interface. The role of this ubiquitous oxide layer cannot be overlooked, as the adhesive properties of the oxide or oxide-metal system can be expected to differ profoundly from the adhesive properties of a bare metal surface. We report on the development of a computational method for molecular-dynamics simulations, which explicitly includes variable charge transfer between anions and cations. This method is found to be capable of describing the elastic properties, surface energies, and surface relaxation of crystalline metal oxides accurately. We discuss in detail results using this method for α-alumina and several of its low-index faces.

  20. Oxidative stress in kidney transplantation: causes, consequences, and potential treatment.

    PubMed

    Nafar, Mohsen; Sahraei, Zahra; Salamzadeh, Jamshid; Samavat, Shiva; Vaziri, Nosartolah D

    2011-11-01

    Oxidative stress is a major mediator of adverse outcomes throughout the course of transplantation. Transplanted kidneys are prone to oxidative stress-mediated injury by pre-transplant and post-transplant conditions that cause reperfusion injury or imbalance between oxidants and antioxidants. Besides adversely affecting the allograft, oxidative stress and its constant companion, inflammation, cause cardiovascular disease, cancer, metabolic syndrome, and other disorders in transplant recipients. Presence and severity of oxidative stress can be assessed by various biomarkers produced from interaction of reactive oxygen species with lipids, proteins, nucleic acids, nitric oxide, glutathione, etc. In addition, expression and activities of redox-sensitive molecules such as antioxidant enzymes can serve as biomarkers of oxidative stress. Via activation of nuclear factor kappa B, oxidative stress promotes inflammation which, in turn, amplifies oxidative stress through reactive oxygen species generation by activated immune cells. Therefore, inflammation markers are indirect indicators of oxidative stress. Many treatment options have been evaluated in studies conducted at different stages of transplantation in humans and animals. These studies have provided useful strategies for use in donors or in organ preservation solutions. However, strategies tested for use in post-transplant phase have been largely inconclusive and controversial. A number of therapeutic options have been exclusively examined in animal models and only a few have been tested in humans. Most of the clinical investigations have been of short duration and have provided no insight into their impact on the long-term survival of transplant patients. Effective treatment of oxidative stress in transplant population remains elusive and awaits future explorations.

  1. Composition and anion ordering in some Fe II-III hydroxysalt green rusts (carbonate, oxalate, methanoate): The fougerite mineral

    NASA Astrophysics Data System (ADS)

    Génin, Jean-Marie R.; Ruby, Christian

    2008-03-01

    Main features of Fe II-III hydroxysalts (green rusts) are obtained from XRD. Moreover, Mössbauer spectroscopy revealed that several Fe II sites exist. The structure is classified in green rusts one and two (GR1 and GR2) according to the stacking sequence of Fe(OH) 2 brucite-like layers depending on the shape and type of anions inserted within interlayers. Long range order as determined for hydroxysulphate GR2(SO 42-) is extended to distributions of cations and anions within GR1s even though these are not observed by XRD. Abundances of Fe II and Fe III environments within GR1s that intercalate carbonate, oxalate and methanoate (formate) are found for compositions [Fe 6IIFe 2III(OH) 16] 2+·[CO 32-·5H 2O] 2-, [Fe 4IIFe 2III(OH) 12] 2+·[CO 32-·3H 2O] 2-, [Fe 6IIFe 2III(OH) 16] 2+·[C 2O 42-·4H 2O] 2- and [Fe 5IIFe 2III(OH) 14] 2+·[2HCOO -·3H 2O] 2-, which correspond to orders α, β and γ where the cation distances are (2 × a0), (√3 × a0) or a mixture of both, with a ferric molar ratio x = {[Fe III]/[Fe total]} = 1/4, 1/3 and 2/7, respectively. Anion distributions within interlayers are devised and long range orders in other layered double hydroxides could questionably be extended from these models. The formula [Fe 6II(1- x) Fe 6 xIIIO 12H 2(7-3 x) ] 2+·[CO 32-·3H 2O] 2- for the fougerite mineral, which is the oxyhydroxycarbonate obtained by deprotonation of Fe II-III hydroxycarbonate [Fe 4IIFe 2III(OH) 12] 2+·[CO 32-·3H 2O] 2- where x ∈ [1/3,2/3] is confirmed.

  2. Accurate oxidation potentials of 40 benzene and biphenyl derivatives with heteroatom substituents.

    PubMed

    Luo, Pu; Feinberg, Adam M; Guirado, Gonzalo; Farid, Samir; Dinnocenzo, Joseph P

    2014-10-03

    The redox equilibrium method was used to determine accurate oxidation potentials in acetonitrile for 40 heteroatom-substituted compounds. These include methoxy-substituted benzenes and biphenyls, aromatic amines, and substituted acetanilides. The redox equilibrium method allowed oxidation potentials to be determined with high precision (≤ ±6 mV). Whereas most of the relative oxidation potentials follow well-established chemical trends, interestingly, the oxidation potentials of substituted N-methylacetanilides were found to be higher than those of the corresponding acetanilides. Density functional theory calculations provided insight into the origin of these surprising results in terms of the preferred conformations of the amides versus their cation radicals.

  3. GOLD B-C-D groups or GOLD II-III-IV grades: Which one better reflects the functionality of patients with chronic obstructive pulmonary disease?

    PubMed

    Moreira, Graciane L; Donária, Leila; Furlanetto, Karina C; Paes, Thais; Sant'Anna, Thaís; Hernandes, Nidia A; Pitta, Fabio

    2015-05-01

    The aim of this article is to investigate which global initiative for chronic obstructive lung disease (GOLD) classification (B-C-D or II-III-IV) better reflects the functionality of patients with moderate to very severe chronic obstructive pulmonary disease (COPD). Ninety patients with COPD were classified according to the GOLD B-C-D and II-III-IV classifications. Functionality was assessed by different outcomes: 6-min walk test (6MWT), activities of daily living (ADL) (London Chest ADL Scale), and daily life activity/inactivity variables assessed by activity monitoring (SenseWear armband, Pittsburgh, Pennsylvania, USA). The 6MWT was the only outcome significantly associated with both the GOLD classifications. Good functionality as assessed by the 6MWT was observed in 80%, 69%, and 43.5% (GOLD B, C, and D, respectively) and 81%, 59%, and 29% (GOLD II, III, and IV, respectively) of the patients. Association (V Cramer's) and correlation (Spearman) coefficients of 6MWT with GOLD B-C-D and II-III-IV were V = 0.30, r = -0.35, and V = 0.37, r = -0.25, respectively. Neither GOLD classification showed V or r ≥ 0.30 with any other functionality outcome. Both the GOLD B-C-D and II-III-IV classifications do not reflect well COPD patients' functionality. Despite low association and correlation coefficients in general, both GOLD classifications were better associated with functional exercise capacity (6MWT) than with subjectively assessed ADL and objectively assessed outcomes of physical activity/inactivity. © The Author(s) 2015.

  4. Does internal mammary node irradiation affect treatment outcome in clinical stage II-III breast cancer patients receiving neoadjuv ant chemotherapy?

    PubMed

    Kim, Kyung Hwan; Noh, Jae Myoung; Kim, Yong Bae; Chang, Jee Suk; Keum, Ki Chang; Huh, Seung Jae; Choi, Doo Ho; Park, Won; Suh, Chang-Ok

    2015-08-01

    The purpose of this study is to assess the value of internal mammary node irradiation (IMNI) in patients receiving postoperative radiotherapy after neoadjuvant chemotherapy (NAC) using modern systemic therapy. Between 2001 and 2009, 521 consecutive patients with clinical stage II-III breast cancer received NAC and postoperative radiotherapy. With a consistent policy, the treating radiation oncologist either included (N = 284) or excluded (N = 237) the internal mammary node in the treatment volume. Anthracycline- and taxane-based chemotherapy was provided to 482 (92.5 %) patients. To account for the unbalanced characteristics between the two groups, we performed propensity score matching and covariate adjustment using the propensity score. The median follow-up duration was 71 months (range 31-153 months). The 5-year disease-free survival (DFS) with and without IMNI was 81.8 and 72.7 %, respectively (p = 0.019). The benefit of IMNI varied according to patient characteristics such that it was more apparent in patients with N1-2 disease, inner/central location, and triple-negative subtype. After adjusting for all potential confounding variables, IMNI was independently associated with improved DFS (p = 0.049). The significant effect of IMNI on DFS was sustained after propensity score matching (p = 0.040) and covariate adjustment using the propensity score (p = 0.048). Symptomatic radiation pneumonitis developed in 9 (3.2 %) patients receiving IMNI. Our results indicated that IMNI was associated with a significant improvement in DFS with low toxicity rate for breast cancer patients receiving NAC. Further prospective studies are warranted to confirm the effect of IMNI in the NAC setting.

  5. Systemic, postsymptomatic antisense oligonucleotide rescues motor unit maturation delay in a new mouse model for type II/III spinal muscular atrophy

    PubMed Central

    Bogdanik, Laurent P.; Osborne, Melissa A.; Davis, Crystal; Martin, Whitney P.; Austin, Andrew; Rigo, Frank; Bennett, C. Frank; Lutz, Cathleen M.

    2015-01-01

    Clinical presentation of spinal muscular atrophy (SMA) ranges from a neonatal-onset, very severe disease to an adult-onset, milder form. SMA is caused by the mutation of the Survival Motor Neuron 1 (SMN1) gene, and prognosis inversely correlates with the number of copies of the SMN2 gene, a human-specific homolog of SMN1. Despite progress in identifying potential therapies for the treatment of SMA, many questions remain including how late after onset treatments can still be effective and what the target tissues should be. These questions can be addressed in part with preclinical animal models; however, modeling the array of SMA severities in the mouse, which lacks SMN2, has proven challenging. We created a new mouse model for the intermediate forms of SMA presenting with a delay in neuromuscular junction maturation and a decrease in the number of functional motor units, all relevant to the clinical presentation of the disease. Using this new model, in combination with clinical electrophysiology methods, we found that administering systemically SMN-restoring antisense oligonucleotides (ASOs) at the age of onset can extend survival and rescue the neurological phenotypes. Furthermore, these effects were also achieved by administration of the ASOs late after onset, independent of the restoration of SMN in the spinal cord. Thus, by adding to the limited repertoire of existing mouse models for type II/III SMA, we demonstrate that ASO therapy can be effective even when administered after onset of the neurological symptoms, in young adult mice, and without being delivered into the central nervous system. PMID:26460027

  6. Natural Oxidant Demand Variability, Potential Controls, and Implications for in Situ, Oxidation-Based Remediation of Contaminated Groundwater

    NASA Astrophysics Data System (ADS)

    Dettmer, A.; Cruz, S.; Dungan, B.; Holguin, F. O.; Ulery, A. L.; Hunter, B.; Carroll, K. C.

    2014-12-01

    Naturally occurring reduced species associated with subsurface materials can impose a significant natural oxidant demand (NOD), which is the bulk consumption of oxidants by soil water, minerals, and organic matter. Although injection of oxidants has been used for chemical transformation of organic contaminants, NOD represents a challenge for the in-situ delivery of oxidants as a remediation alternative. Co-injection of complexation agents with oxidants has been proposed to facilitate the delivery of oxidants for in situ chemical oxidation remediation of contaminated groundwater. This study investigates variability of NOD for different oxidants and sediments. The effect of the addition of various complexation agents, including EDTA, tween 80, hydroxypropyl-beta-cyclodextrin (HPCD), humic acid, and four generations of poly(amidoamine) (PAMAM) dendrimers, on the NOD was also examined. NOD was measured for a clay loam (collected from Air Force Plant 44 in Tucson, AZ). Varying amounts of biosolids were mixed with subsamples of the clay loam to create three additional reference soils in order to study the effect of organic matter and other soil characteristics on the NOD. Bench-scale laboratory experiments were conducted to determine the NOD for various oxidants, using the four soils, and replicated with and without various delivery agents. Measured NOD showed variability for each soil and oxidant composition. Additionally, significant differences were observed in NOD with the addition of delivery agents. The results support the elucidation of potential controls over NOD and have implications for in situ, oxidation-based remediation of contaminated groundwater.

  7. Antifungal metabolites (monorden, monocillins I, II, III) from Colletotrichum graminicola, a systemic vascular pathogen of maize.

    PubMed

    Wicklow, Donald T; Jordan, Annalisa M; Gloer, James B

    2009-12-01

    Colletotrichum graminicola is a systemic vascular pathogen that causes anthracnose stalk rot and leaf blight of maize. In the course of an effort to explore the potential presence and roles of C. graminicola metabolites in maize, ethyl acetate extracts of solid substrate fermentations of several C. graminicola isolates from Michigan and Illinois were found to be active against Aspergillus flavus and Fusarium verticillioides, both mycotoxin-producing seed-infecting fungal pathogens. Chemical investigations of the extract of one such isolate (NRRL 47511) led to the isolation of known metabolites monorden (also known as radicicol) and monocillins I-III as major components. Monorden and monocillin I displayed in vitro activity against the stalk- and ear-rot pathogen Stenocarpella maydis while only the most abundant metabolite (monorden) showed activity against foliar pathogens Alternaria alternata, Bipolaris zeicola, and Curvularia lunata. Using LC-HRESITOFMS, monorden was detected in steam-sterilized maize stalks and stalk residues inoculated with C. graminicola but not in the necrotic stalk tissues of wound-inoculated plants grown in an environmental chamber. Monorden and monocillin I can bind and inhibit plant Hsp90, a chaperone of R-proteins. It is hypothesized that monorden and monocillins could support the C. graminicola disease cycle by disrupting maize plant defenses and by excluding other fungi from necrotic tissues and crop residues. This is the first report of natural products from C. graminicola, as well as the production of monorden and monocillins by a pathogen of cereals.

  8. Synthesis, characterization, and biological activity of platinum II, III, and IV pivaloamidine complexes.

    PubMed

    Sinisi, Marilù; Gandin, Valentina; Saltarella, Teresa; Intini, Francesco P; Pacifico, Concetta; Marzano, Christine; Natile, Giovanni

    2014-10-01

    Imino ligands have proven to be able to activate the trans geometry of platinum(II) complexes towards antitumor activity. These ligands, like aromatic N-donor heterocycles, have a planar shape but, different from the latter, have still an H atom on the coordinating nitrogen which can be involved in H-bond formation. Three classes of imino ligands have been extensively investigated: iminoethers (HN=C(R)OR'), ketimines (HN=CRR'), and amidines (HN=C(R)NR'R″). The promising efficacy of the platinum compounds with amidines (activity comparable to that of cisplatin for cis complexes and much greater than that of transplatin for trans complexes) prompted us to extend the investigation to amidine complexes with a bulkier organic residue (R = t-Bu). The tert-butyl group can confer greater affinity for lipophilic environments, thus potentiating the cellular uptake of the compound. In the present study we describe the synthesis and characterization of pivaloamidine complexes of platinum(II), (cis and trans-[PtCl2(NH3){Z-HN=C(t-Bu)NH2}] and cis and trans-[PtCl2{Z-HN=C(t-Bu)NH2}2]), platinum(III) ([Pt2Cl4{HN=C(t-Bu)NH}2(NH3)2]), and platinum(IV) (trans-[PtCl4(NH3){Z-HN=C(t-Bu)NH2}] and trans-[PtCl4{Z-HN=C(t-Bu)NH2}2]). The cytotoxicity of all new Pt complexes was tested toward a panel of cultured cancer cell lines, including cisplatin and multidrug resistant variants. In addition, cellular uptake and DNA binding, perturbations of cell cycle progression, induction of apoptosis, and p53 activation were investigated for the most promising compound trans-[PtCl2(NH3){Z-HN=C(t-Bu)NH2}]. Remarkably, the latter complex was able to overcome both acquired and intrinsic cisplatin resistance.

  9. Equatorial π-stacking interactions in diruthenium (II,III) tetracarboxylate complexes containing extended π-systems

    NASA Astrophysics Data System (ADS)

    O'Rourke, Natasha F.; Ronaldson, Michael; Stanley Cameron, T.; Wang, Ruiyao; Aquino, Manuel A. S.

    2013-11-01

    The synthesis of three new valent-averaged tetracarboxylatodiruthenium (II,III) complexes, [Ru2(1-naphthylacetate)4(H2O)2](PF6)ṡ4THF, 1ṡ4THF, [Ru2(2-naphthoate)4(THF)2](PF6)ṡ3THF, 2ṡ3THF, and [Ru2(coumarin-3-carboxylate)4(MeOH)2](PF6)ṡMeOHṡH2O, 3ṡMeOHṡH2O, was accomplished using a well documented carboxylate exchange reaction. All three complexes were thoroughly characterized using infrared and UV-Vis spectroscopies, elemental analysis and X-ray diffraction. Due to the extended π-systems present, two of the complexes, 2ṡ3THF and 3ṡMeOHṡH2O, display extensive π-stacking in two dimensions, with similar interactions notably absent in 1ṡ4THF due to the perpendicular orientation of the naphthyl rings. Modest H-bonding is seen in complexes 1ṡ4THF and 3ṡMeOHṡH2O. As these types of complexes are noted secondary building units (SBU's) in the construction of metal-organic frameworks (MOF's), the significance of these interactions in stabilizing even larger, supramolecular structures, are noted.

  10. Image analysis-derived metrics of histomorphological complexity predicts prognosis and treatment response in stage II-III colon cancer

    PubMed Central

    Mezheyeuski, Artur; Hrynchyk, Ina; Karlberg, Mia; Portyanko, Anna; Egevad, Lars; Ragnhammar, Peter; Edler, David; Glimelius, Bengt; Östman, Arne

    2016-01-01

    The complexity of tumor histomorphology reflects underlying tumor biology impacting on natural course and response to treatment. This study presents a method of computer-aided analysis of tissue sections, relying on multifractal (MF) analyses, of cytokeratin-stained tumor sections which quantitatively evaluates of the morphological complexity of the tumor-stroma interface. This approach was applied to colon cancer collection, from an adjuvant treatment randomized study. Metrics obtained with the method acted as independent markers for natural course of the disease, and for benefit of adjuvant treatment. Comparative analyses demonstrated that MF metrics out-performed standard histomorphological features such as tumor grade, budding and configuration of invasive front. Notably, the MF analyses-derived “αmax” –metric constitutes the first response-predictive biomarker in stage II-III colon cancer showing significant interactions with treatment in analyses using a randomized trial-derived study population. Based on these results the method appears as an attractive and easy-to-implement tool for biomarker identification. PMID:27805003

  11. Flexible selection of a single treatment incorporating short-term endpoint information in a phase II/III clinical trial.

    PubMed

    Stallard, Nigel; Kunz, Cornelia Ursula; Todd, Susan; Parsons, Nicholas; Friede, Tim

    2015-10-15

    Seamless phase II/III clinical trials in which an experimental treatment is selected at an interim analysis have been the focus of much recent research interest. Many of the methods proposed are based on the group sequential approach. This paper considers designs of this type in which the treatment selection can be based on short-term endpoint information for more patients than have primary endpoint data available. We show that in such a case, the familywise type I error rate may be inflated if previously proposed group sequential methods are used and the treatment selection rule is not specified in advance. A method is proposed to avoid this inflation by considering the treatment selection that maximises the conditional error given the data available at the interim analysis. A simulation study is reported that illustrates the type I error rate inflation and compares the power of the new approach with two other methods: a combination testing approach and a group sequential method that does not use the short-term endpoint data, both of which also strongly control the type I error rate. The new method is also illustrated through application to a study in Alzheimer's disease. © 2015 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.

  12. Methodological quality of animal studies of neuroprotective agents currently in phase II/III acute ischemic stroke trials.

    PubMed

    Philip, Maria; Benatar, Michael; Fisher, Marc; Savitz, Sean I

    2009-02-01

    Numerous neuroprotective agents have proven effective in animal stroke studies, but every drug has failed to achieve its primary outcome when brought forward to clinical trials. We analyzed the quality and adequacy of animal studies supporting the efficacy of NXY-059 and other neuroprotective agents that are currently being investigated in phase II/III trials. We conducted a systematic search of all neuroprotective drugs in Phase II or III trials and collected data from animal studies of focal cerebral ischemia testing agents systemically administered within 24 hours of occlusion. The methodological rigor of each individual study was evaluated using 5 criteria derived from the STAIR guidelines. The adequacy of the preclinical "package" for each drug was then evaluated by combining the results of all studies for each drug to determine which of a further 5 STAIR criteria were met before moving forward from animal to human studies. Our search yielded 13 agents of which 10 had published data in peer-reviewed journals. There is substantial within-drug variability in the quality of preclinical studies as well as substantial variation in the completeness of the collective preclinical literature for different drugs. There has been little or no improvement in the quality of animal studies since NXY-059, and current agents have not been subjected to a more complete preclinical evaluation. There is significant heterogeneity in the quality of animal testing for neuroprotective agents in stroke. Drugs in the post-SAINT era have not been subjected to more thorough preclinical evaluation.

  13. Cux1 Enables Interhemispheric Connections of Layer II/III Neurons by Regulating Kv1-Dependent Firing.

    PubMed

    Rodríguez-Tornos, Fernanda M; Briz, Carlos G; Weiss, Linnea A; Sebastián-Serrano, Alvaro; Ares, Saúl; Navarrete, Marta; Frangeul, Laura; Galazo, Maria; Jabaudon, Denis; Esteban, José A; Nieto, Marta

    2016-02-03

    Neuronal subtype-specific transcription factors (TFs) instruct key features of neuronal function and connectivity. Activity-dependent mechanisms also contribute to wiring and circuit assembly, but whether and how they relate to TF-directed neuronal differentiation is poorly investigated. Here we demonstrate that the TF Cux1 controls the formation of the layer II/III corpus callosum (CC) projections through the developmental transcriptional regulation of Kv1 voltage-dependent potassium channels and the resulting postnatal switch to a Kv1-dependent firing mode. Loss of Cux1 function led to a decrease in the expression of Kv1 transcripts, aberrant firing responses, and selective loss of CC contralateral innervation. Firing and innervation were rescued by re-expression of Kv1 or postnatal reactivation of Cux1. Knocking down Kv1 mimicked Cux1-mediated CC axonal loss. These findings reveal that activity-dependent processes are central bona fide components of neuronal TF-differentiation programs and establish the importance of intrinsic firing modes in circuit assembly within the neocortex.

  14. Contrasts in oxidative potential and other particulate matter characteristics collected near major streets and background locations.

    PubMed

    Boogaard, Hanna; Janssen, Nicole A H; Fischer, Paul H; Kos, Gerard P A; Weijers, Ernie P; Cassee, Flemming R; van der Zee, Saskia C; de Hartog, Jeroen J; Brunekreef, Bert; Hoek, Gerard

    2012-02-01

    Measuring the oxidative potential of airborne particulate matter (PM) may provide a more health-based exposure measure by integrating various biologically relevant properties of PM into a single predictor of biological activity. We aimed to assess the contrast in oxidative potential of PM collected at major urban streets and background locations, the associaton of oxidative potential with other PM characteristics, and the oxidative potential in different PM size fractions. Measurements of PM with aerodynamic diameter ≤ 10 μm (PM10), PM with aerodynamic diameter ≤ 2.5 μm (PM2.5), soot, elemental composition, and oxidative potential of PM were conducted simultaneously in samples from 8 major streets and 10 urban and suburban background locations in the Netherlands. Six 1-week measurements were performed at each location over a 6-month period in 2008. Oxidative potential was measured as the ability to generate hydroxyl radicals in the presence of hydrogen peroxide in all PM10 samples and a subset of PM2.5 samples. The PM10 oxidative potential of samples from major streets was 3.6 times higher than at urban background locations, exceeding the contrast for PM mass, soot, and all measured chemical PM characteristics. The contrast between major streets and suburban background locations was even higher (factor of 6.5). Oxidative potential was highly correlated with soot, barium, chromium, copper, iron, and manganese. Oxidative potential of PM10 was 4.6 times higher than the oxidative potential of PM2.5 when expressed per volume unit and 3.1 times higher when expressed per mass unit. The oxidative potential of PM near major urban roads was highly elevated compared with urban and suburban background locations, and the contrast was greater than that for any other measured PM characteristic.

  15. Characterization of the thrombogenic potential of surface oxides on stainless steel for implant purposes

    NASA Astrophysics Data System (ADS)

    Shih, Chun-Che; Shih, Chun-Ming; Su, Yea-Yang; Chang, Mau-Song; Lin, Shing-Jong

    2003-12-01

    Marketed stents are manufactured from various metals and passivated with different degrees of surface oxidation. The functional surface oxides on the degree of antithrombotic potential were explored through a canine femoral extracorporeal circuit model. Related properties of these oxide films were studied by open-circuit potential, current density detected at open-circuit potential, the electrochemical impedance spectroscopy, transmission electron microscopy, Auger spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. Experimental evidences showed that blood clot weight after a 30-min follow-up was significantly lower for the stainless steel wire passivated with amorphous oxide (AO) compared to the wire passivated with polycrystalline oxide (PO) or commercial as-received wire coils (AS). Surface characterizations showed that a stable negative current density at open-circuit potential and a significant lower potential were found for the wire surface passivated with AO than for the surface passivated with PO. Time constant of AO is about 25 times larger than that of polycrystalline oxide. Significant difference in oxide grain sizes was found between PO and AO. Surface chemistries revealed by the AES and XPS spectra indicated the presence of a Cr- and oxygen-rich surface oxide for AO, and a Fe-rich and oxygen-lean surface oxide for PO. These remarkable characteristics of AO surface film might have a potential to provide for excellent antithrombotic characteristics for the 316L stainless steel stents.

  16. Monoterpenol Oxidative Metabolism: Role in Plant Adaptation and Potential Applications

    PubMed Central

    Ilc, Tina; Parage, Claire; Boachon, Benoît; Navrot, Nicolas; Werck-Reichhart, Danièle

    2016-01-01

    Plants use monoterpenols as precursors for the production of functionally and structurally diverse molecules, which are key players in interactions with other organisms such as pollinators, flower visitors, herbivores, fungal, or microbial pathogens. For humans, many of these monoterpenol derivatives are economically important because of their pharmaceutical, nutraceutical, flavor, or fragrance applications. The biosynthesis of these derivatives is to a large extent catalyzed by enzymes from the cytochrome P450 superfamily. Here we review the knowledge on monoterpenol oxidative metabolism in plants with special focus on recent elucidations of oxidation steps leading to diverse linalool and geraniol derivatives. We evaluate the common features between oxidation pathways of these two monoterpenols, such as involvement of the CYP76 family, and highlight the differences. Finally, we discuss the missing steps and other open questions in the biosynthesis of oxygenated monoterpenol derivatives. PMID:27200002

  17. Oxidative Stress Status in Childhood Obesity: A Potential Risk Predictor

    PubMed Central

    Kilic, Elif; Özer, Ömer Faruk; Erek, Aybala Toprak; Erman, Hayriye; Torun, Emel; Ayhan, Sıddıka Kesgin; Caglar, Hifa Gülru; Selek, Sahbettin; Kocyigit, Abdurrahim

    2016-01-01

    Background Childhood obesity characterized by excessive fat in the body is one of the most serious health problems worldwide due to the social, medical, and physiological complications. Obesity and associated diseases are triggering factors for oxidative stress and inflammation. The aim of this study was to explore the possible association between childhood obesity and inflammatory and oxidative status. Material/Methods Thirty-seven obese children and 37 healthy controls selected from among children admitted to BLIND University Paediatrics Department were included in the study. Anthropometric measurements were performed using standard methods. Glucose, lipid parameters, CRP, insulin, total oxidant status (TOS), total anti-oxidant status (TAS) levels, and total thiol levels (TTL) were measured in serum. HOMA index (HOMA-IR) were calculated. The differences between the groups were evaluated statistically using the Mann-Whitney U test. Results Body mass index was significantly higher in the obese group (median: 28.31(p<0.001). Glucose metabolism, insulin, and HOMA-IR levels were significantly higher in the obese group (both p<0.001). Total cholesterol, HDL cholesterol, LDL cholesterol, and triglyceride levels were significantly higher in the obese group (p<0.001). TAS (med: 2.5 μmol Trolox eq/L (1.7–3.3)) and TOS (med: 49.1 μmol H2O2 eq/L (34.5–78.8)) levels and TTL (med: 0.22 mmol/L (0.16–0.26)) were significantly higher in the obese group (p=0.001). CRP levels showed positive correlation with TOS and negative correlation with TTL levels (p=0.005, r=0.473; p=0.01, r=−0.417; respectively). TTL levels exhibited negative correlation with TOS levels (p=0.03, r=−0.347). Conclusions In conclusion, obese children were exposed to more oxidative burden than children with normal weight. Increased systemic oxidative stress induced by childhood obesity can cause development of obesity-related complications and diseases. Widely focussed studies are required on the use

  18. Randomized phase II/III clinical trial of elpamotide for patients with advanced pancreatic cancer: PEGASUS-PC Study.

    PubMed

    Yamaue, Hiroki; Tsunoda, Takuya; Tani, Masaji; Miyazawa, Motoki; Yamao, Kenji; Mizuno, Nobumasa; Okusaka, Takuji; Ueno, Hideki; Boku, Narikazu; Fukutomi, Akira; Ishii, Hiroshi; Ohkawa, Shinichi; Furukawa, Masayuki; Maguchi, Hiroyuki; Ikeda, Masafumi; Togashi, Yosuke; Nishio, Kazuto; Ohashi, Yasuo

    2015-07-01

    Gemcitabine is a key drug for the treatment of pancreatic cancer; however, with its limitation in clinical benefits, the development of another potent therapeutic is necessary. Vascular endothelial growth factor receptor 2 is an essential target for tumor angiogenesis, and we have conducted a phase I clinical trial using gemcitabine and vascular endothelial growth factor receptor 2 peptide (elpamotide). Based on the promising results of this phase I trial, a multicenter, randomized, placebo-controlled, double-blind phase II/III clinical trial has been carried out for pancreatic cancer. The eligibility criteria included locally advanced or metastatic pancreatic cancer. Patients were assigned to either the Active group (elpamotide + gemcitabine) or Placebo group (placebo + gemcitabine) in a 2:1 ratio by the dynamic allocation method. The primary endpoint was overall survival. The Harrington-Fleming test was applied to the statistical analysis in this study to evaluate the time-lagged effect of immunotherapy appropriately. A total of 153 patients (Active group, n = 100; Placebo group, n = 53) were included in the analysis. No statistically significant differences were found between the two groups in the prolongation of overall survival (Harrington-Fleming P-value, 0.918; log-rank P-value, 0.897; hazard ratio, 0.87, 95% confidence interval [CI], 0.486-1.557). Median survival time was 8.36 months (95% CI, 7.46-10.18) for the Active group and 8.54 months (95% CI, 7.33-10.84) for the Placebo group. The toxicity observed in both groups was manageable. Combination therapy of elpamotide with gemcitabine was well tolerated. Despite the lack of benefit in overall survival, subgroup analysis suggested that the patients who experienced severe injection site reaction, such as ulceration and erosion, might have better survival.

  19. Reducing the Time From Diagnosis to Treatment of Patients With Stage II/III Rectal Cancer at a Large Public Hospital

    PubMed Central

    Leslie, Lori A.; Jacobs, Ryan W.; Millas, Stefanos; Surabhi, Venkateswar; Mok, Henry; Jhaveri, Pavan; Kott, Marylee M.; Jackson, Lymesia; Rieber, Alyssa; Bhadkamkar, Nishin A.

    2016-01-01

    Curative-intent therapy for stage II/III rectal cancer is necessarily complex. Current guidelines by the National Comprehensive Cancer Network recommend preoperative concurrent chemoradiation followed by resection and additional adjuvant chemotherapy. We used standard quality improvement methodology to implement a cost-effective intervention that reduced the time from diagnosis to treatment of patients with stage II/III rectal cancer by approximately 30% in a large public hospital in Houston, Texas. Implementation of the program resulted in a reduction in time from pathologic diagnosis to treatment of 29% overall, from 62 to 44 days. These gains were cost neutral and resulted from improvements in scheduling and coordination of care alone. Our results suggest that: (1) quality improvement methodology can be successfully applied to multidisciplinary cancer care, (2) effective interventions can be cost neutral, and (3) effective strategies can overcome complexities such as having multiple sites of care, high staff turnover, and resource limitations. PMID:26869658

  20. Changes in the BDNF-immunopositive cell population of neocortical layers I and II/III after focal cerebral ischemia in rats.

    PubMed

    Choi, Yongwon; Kang, Sung Goo; Kam, Kyung-Yoon

    2015-04-24

    Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family and is widely distributed in the central nervous system, including the cerebral cortex. BDNF plays an important role in normal neural development, survival of existing neurons, and activity-dependent neuroplasticity. BDNF can also be neuroprotective and evoke neurogenesis in certain pathological conditions, such as cerebral ischemia. Neocortical layer I is an important region that can integrate feedforward and feedback information from other cortical areas and subcortical regions. In addition, it has recently been proposed as a possible source of neuronal progenitor cells after ischemia. Therefore, we investigated changes in the BDNF-immunoreactive cell population of neocortical layers I and II/III after middle cerebral artery occlusion (MCAO)-induced cerebral ischemia in rats. In unaffected condition, the number of BDNF(+) cells in layer I was significantly less than in layer II/III in the cingulate cortex and in the motor and sensory areas. The increase in the number of BDNF(+) cells in layer I 8 days after MCAO was more remarkable than layer II/III, in all regions except the area of cingulate cortex farthest from the infarct core. Only BDNF(+)-Ox-42(+) cells showed a tendency to increase consistently toward the infarct core in both layers I and II/III, implying a major source of BDNF for response to ischemic injury. The present study suggests that some beneficial effects during recovery from ischemic injury, such as increased supportive microglia/macrophages, occur owing to a sensitive response of BDNF in layer I.

  1. High expression of the stem cell marker nestin is an adverse prognostic factor in WHO grade II-III astrocytomas and oligoastrocytomas

    PubMed Central

    Hatanpaa, Kimmo J.; Foong, Chan; Raisanen, Jack M.; Oliver, Dwight; Hiemenz, Matthew C.; Burns, Dennis K.; White, Charles L.; Whitworth, L. Anthony; Mickey, Bruce; Stegner, Martha; Habib, Amyn A.; Fink, Karen; Maher, Elizabeth A.; Bachoo, Robert M.

    2015-01-01

    Infiltrating astrocytomas and oligoastrocytomas of low to anaplastic grade (WHO grades II and III), in spite of being associated with a wide range of clinical outcomes, can be difficult to subclassify and grade by the current histopathologic criteria. Unlike oligodendrogliomas and anaplastic oligodendrogliomas that can be identified by the 1p/19q codeletion and the more malignant glioblastomas (WHO grade IV astrocytomas) that can be diagnosed solely based on objective features on routine hematoxylin and eosin sections, no such objective criteria exist for the subclassification of grade II-III astrocytomas and oligoastrocytomas (A+OA II-III). In this study, we evaluated the prognostic and predictive value of the stem cell marker nestin in adult A+OA II-III (n=50) using immunohistochemistry and computer-assisted analysis on tissue microarrays. In addition, the correlation between nestin mRNA level and total survival was analyzed in the NCI Rembrandt database. The results showed that high nestin expression is a strong adverse prognostic factor for total survival (p=0.0004). The strength of the correlation was comparable to but independent of the isocitrate dehydrogenase 1/2 (IDH 1/2) mutation status. Histopathological grading and subclassification did not correlate significantly with outcome, although the interpretation of this finding is limited by the fact that grade III tumors were treated more aggressively than grade II tumors. These results suggest that nestin level and IDH 1/2 mutation status are strong prognostic features in A+OA II-III and possibly more helpful for treatment planning than routine histopathological variables such as oligodendroglial component (astrocytoma vs. oligoastrocytoma) and WHO grade (grade II vs. III). PMID:24519516

  2. High expression of the stem cell marker nestin is an adverse prognostic factor in WHO grade II-III astrocytomas and oligoastrocytomas.

    PubMed

    Hatanpaa, Kimmo J; Hu, Tianshen; Vemireddy, Vamsidhara; Foong, Chan; Raisanen, Jack M; Oliver, Dwight; Hiemenz, Matthew C; Burns, Dennis K; White, Charles L; Whitworth, L Anthony; Mickey, Bruce; Stegner, Martha; Habib, Amyn A; Fink, Karen; Maher, Elizabeth A; Bachoo, Robert M

    2014-03-01

    Infiltrating astrocytomas and oligoastrocytomas of low to anaplastic grade (WHO grades II and III), in spite of being associated with a wide range of clinical outcomes, can be difficult to subclassify and grade by the current histopathologic criteria. Unlike oligodendrogliomas and anaplastic oligodendrogliomas that can be identified by the 1p/19q codeletion and the more malignant glioblastomas (WHO grade IV astrocytomas) that can be diagnosed solely based on objective features on routine hematoxylin and eosin sections, no such objective criteria exist for the subclassification of grade II-III astrocytomas and oligoastrocytomas (A+OA II-III). In this study, we evaluated the prognostic and predictive value of the stem cell marker nestin in adult A+OA II-III (n = 50) using immunohistochemistry and computer-assisted analysis on tissue microarrays. In addition, the correlation between nestin mRNA level and total survival was analyzed in the NCI Rembrandt database. The results showed that high nestin expression is a strong adverse prognostic factor for total survival (p = 0.0004). The strength of the correlation was comparable to but independent of the isocitrate dehydrogenase 1/2 (IDH 1/2) mutation status. Histopathological grading and subclassification did not correlate significantly with outcome, although the interpretation of this finding is limited by the fact that grade III tumors were treated more aggressively than grade II tumors. These results suggest that nestin level and IDH 1/2 mutation status are strong prognostic features in A+OA II-III and possibly more helpful for treatment planning than routine histopathological variables such as oligodendroglial component (astrocytoma vs. oligoastrocytoma) and WHO grade (grade II vs. III).

  3. Role of nitric oxide in long-term potentiation of the rat medial vestibular nuclei.

    PubMed

    Grassi, S; Pettorossi, V E

    2000-01-01

    In rat brainstem slices, we investigated the role of nitric oxide in long-term potentiation induced in the ventral portion of the medial vestibular nuclei by high-frequency stimulation of the primary vestibular afferents. The nitric oxide scavenger [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide ] and the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester were administered before and after induction of potentiation. Both drugs completely prevented long-term potentiation, whereas they did not impede the potentiation build-up, or affect the already established potentiation. These results demonstrate that the induction, but not the maintenance of vestibular long-term potentiation, depends on the synthesis and release into the extracellular medium of nitric oxide. In addition, we analysed the effect of the nitric oxide donor sodium nitroprusside on vestibular responses. Sodium nitroprusside induced long-term potentiation, as evidenced through the field potential enhancement and unit peak latency decrease. This potentiation was impeded by D, L-2-amino-5-phosphonopentanoic acid, and was reduced under blockade of synaptosomal platelet-activating factor receptors by ginkgolide B and group I metabotropic glutamate receptors by (R,S)-1-aminoindan-1, 5-dicarboxylic acid. When reduced, potentiation fully developed following the washout of antagonist, demonstrating an involvement of platelet-activating factor and group I metabotropic glutamate receptors in its full development. Potentiation induced by sodium nitroprusside was also associated with a decrease in the paired-pulse facilitation ratio, which persisted under ginkgolide B, indicating that nitric oxide increases glutamate release independently of platelet-activating factor-mediated presynaptic events. We suggest that nitric oxide, released after the activation of N-methyl-D-aspartate receptors, acts as a retrograde messenger leading to an enhancement of glutamate release to a

  4. Factors Driving Potential Ammonia Oxidation in Canadian Arctic Ecosystems: Does Spatial Scale Matter?

    PubMed Central

    Banerjee, Samiran

    2012-01-01

    Ammonia oxidation is a major process in nitrogen cycling, and it plays a key role in nitrogen limited soil ecosystems such as those in the arctic. Although mm-scale spatial dependency of ammonia oxidizers has been investigated, little is known about the field-scale spatial dependency of aerobic ammonia oxidation processes and ammonia-oxidizing archaeal and bacterial communities, particularly in arctic soils. The purpose of this study was to explore the drivers of ammonia oxidation at the field scale in cryosols (soils with permafrost within 1 m of the surface). We measured aerobic ammonia oxidation potential (both autotrophic and heterotrophic) and functional gene abundance (bacterial amoA and archaeal amoA) in 279 soil samples collected from three arctic ecosystems. The variability associated with quantifying genes was substantially less than the spatial variability observed in these soils, suggesting that molecular methods can be used reliably evaluate spatial dependency in arctic ecosystems. Ammonia-oxidizing archaeal and bacterial communities and aerobic ammonia oxidation were spatially autocorrelated. Gene abundances were spatially structured within 4 m, whereas biochemical processes were structured within 40 m. Ammonia oxidation was driven at small scales (<1m) by moisture and total organic carbon, whereas gene abundance and other edaphic factors drove ammonia oxidation at medium (1 to 10 m) and large (10 to 100 m) scales. In these arctic soils heterotrophs contributed between 29 and 47% of total ammonia oxidation potential. The spatial scale for aerobic ammonia oxidation genes differed from potential ammonia oxidation, suggesting that in arctic ecosystems edaphic, rather than genetic, factors are an important control on ammonia oxidation. PMID:22081570

  5. Adverse Effects of Intraoperative Blood Loss on Long-Term Outcomes after Curative Gastrectomy of Patients with Stage II/III Gastric Cancer.

    PubMed

    Mizuno, Akira; Kanda, Mitsuro; Kobayashi, Daisuke; Tanaka, Chie; Iwata, Naoki; Yamada, Suguru; Fujii, Tsutomu; Nakayama, Goro; Sugimoto, Hiroyuki; Koike, Masahiko; Fujiwara, Michitaka; Kodera, Yasuhiro

    2016-01-01

    Gastrectomy with systemic lymphadenectomy sometimes causes excessive bleeding even by experienced surgeons. The aim of this study was to evaluate how intraoperative estimated blood loss (EBL) affected the long-term outcomes after curative surgery of patients with stage II/III gastric cancer (GC). This study included 203 patients with stage II/III GC who did not receive perioperative blood transfusion between 1999 and 2015. The optimal cutoff and the prognostic significance of EBL were determined retrospectively. The median EBL was 285 ml. Receiver operating characteristic curve analysis identified 400 ml as an optimal cutoff. Patients with EBL ≥400 ml were more likely to have hepatic relapse and worse prognosis compared to those with EBL <400 ml. EBL ≥400 ml was identified as an independent prognostic factor for mortality by multivariable analysis. When patients were subdivided according to administration of adjuvant chemotherapy, there was a significant difference between the EBL ≥400 and <400 ml groups in patients who underwent surgery alone, whereas the prognosis was similar for patients of both groups who received adjuvant chemotherapy. EBL serves as a useful predictor for risk stratification after curative gastrectomy in patients with stage II/III GC. © 2016 S. Karger AG, Basel.

  6. Clinical significance of platelet-derived growth factor receptor-β gene expression in stage II/III gastric cancer with S-1 adjuvant chemotherapy

    PubMed Central

    Higuchi, Akio; Oshima, Takashi; Yoshihara, Kazue; Sakamaki, Kentaro; Aoyama, Toru; Suganuma, Nobuyasu; Yamamoto, Naoto; Sato, Tsutomu; Cho, Haruhiko; Shiozawa, Manabu; Yoshikawa, Takaki; Rino, Yasushi; Kunisaki, Chikara; Imada, Toshio; Masuda, Munetaka

    2017-01-01

    Overall survival remains unsatisfactory in stage II/III gastric cancer, even after curative surgery and adjuvant chemotherapy. Platelet-derived growth factor receptor-β (PDGFR-β) is associated with the proliferation of cancer cells. The present study therefore investigated the association of PDGFR-β gene expression with patient outcome in 134 stage II/III gastric cancer patients who received adjuvant chemotherapy with S-1. Relative PDGFR-β gene expression was measured in surgical cancer tissue and adjacent normal mucosa specimens by reverse transcription-quantitative polymerase chain reaction. The PDGFR-β gene expression levels were found to be significantly higher in the cancer tissues compared with the adjacent normal mucosa. A high level of PDGFR-β gene expression was associated with a significantly poorer 5-year overall survival rate compared with a low level of PDGFR-β expression. Upon multivariate analysis, PDGFR-β gene expression was found to be an independent predictor of survival. Overall, the study indicates that PDGFR-β overexpression in gastric cancer tissues is a useful independent predictor of outcome in patients with stage II/III gastric cancer who receive adjuvant chemotherapy with S-1.

  7. Chlorhexidine markedly potentiates the oxidants scavenging abilities of Candida albicans.

    PubMed

    Ginsburg, I; Koren, E; Feuerstein, O; Zogakis, I P; Shalish, M; Gorelik, S

    2015-10-01

    The oxidant scavenging ability (OSA) of catalase-rich Candida albicans is markedly enhanced by chlorhexidine digluconate (CHX), polymyxin B, the bile salt ursodeoxycholate and by lysophosphatidylcholine, which all act as detergents facilitating the penetration of oxidants and their intracellular decomposition. Quantifications of the OSA of Candida albicans were measured by a highly sensitive luminol-dependent chemiluminescence assay and by the Thurman's assay, to quantify hydrogen peroxide (H2O2). The OSA enhancing activity by CHX depends to some extent on the media on which candida grew. The OSA of candida treated by CHX was modulated by whole human saliva, red blood cells, lysozyme, cationic peptides and by polyphenols. Concentrations of CHX, which killed over 95 % of Candida albicans cells, did not affect the cells' abilities to scavenge reactive oxygen species (ROS). The OSA of Candida cells treated by CHX is highly refractory to H2O2 (50 mM) but is strongly inhibited by hypochlorous acid, lecithin, trypan blue and by heparin. We speculate that similarly to catalase-rich red blood cells, Candida albicans and additional catalase-rich microbiota may also have the ability to scavenge oxidants and thus can protect catalase-negative anaerobes and facultative anaerobes cariogenic streptococci against peroxide and thus secure their survival in the oral cavity.

  8. Global perspective on the oxidative potential of airborne particulate matter: a synthesis of research findings.

    PubMed

    Saffari, Arian; Daher, Nancy; Shafer, Martin M; Schauer, James J; Sioutas, Constantinos

    2014-07-01

    An emerging hypothesis in the field of air pollution is that oxidative stress is one of the important pathways leading to adverse health effects of airborne particulate matter (PM). To advance our understanding of sources and chemical elements contributing to aerosol oxidative potential and provide global comparative data, we report here on the biological oxidative potential associated with size-segregated airborne PM in different urban areas of the world, measured by a biological (cell-based) reactive oxygen species (ROS) assay. Our synthesis indicates a generally greater intrinsic PM oxidative potential as well as higher levels of exposure to redox-active PM in developing areas of the world. Moreover, on the basis of our observations, smaller size fractions are generally associated with higher intrinsic ROS activity compared with larger PM size fractions. Another important outcome of our study is the identification of major species and sources that are associated with ROS activity. Water-soluble transition metals (e.g., Fe, Ni, Cu, Cr, Mn, Zn and V) and water-soluble organic carbon (WSOC) showed consistent correlations with the oxidative potential of airborne PM across different urban areas and size ranges. The major PM sources associated with these chemical species include residual/fuel oil combustion, traffic emissions, and secondary organic aerosol formation, indicating that these sources are major drivers of PM-induced oxidative potential. Moreover, comparison of ROS activity levels across different seasons indicated that photochemical aging increases the intrinsic oxidative potential of airborne PM.

  9. Oxidation-Reduction Potential of Saturated Forest Soils

    Treesearch

    F. T. Bonner; C. W. Ralston

    1968-01-01

    Large decreases in redox potentials of saturated soil over a 25-day incubation period were favored by high temperature and the addition of sucrose, loblolly pine needles (Pinus taeda L. ), or yellow-poplar leaves (Liriodendron tulipifera L.). The addition of a complete nutrient solution had no effect in soils incubated with sucrose, but it reduced the drop in potential...

  10. Flywheel resistance exercise to maintain muscle oxidative potential during unloading.

    PubMed

    Fernandez-Gonzalo, Rodrigo; Irimia, Jose M; Cusso, Roser; Gustafsson, Thomas; Linné, Anneli; Tesch, Per A

    2014-07-01

    As spaceflight compromises skeletal muscle oxidative and aerobic work capacity, this study assessed the efficacy of resistance exercise (RE) to counteract muscle metabolic perturbations induced by 5 wk unilateral lower limb unloading (UL). There were 21 men and women (30-56 yr) who were randomly assigned to either UL with (Group, Grp; UL+RE; N = 10) or without (Grp UL; N = 11) concurrent RE. Iso-inertial RE comprised four sets of seven maximal coupled concentric-eccentric knee extensions executed 2-3 times per week. Percutaneous biopsies were obtained from m. vastus lateralis before and after either intervention. Levels of mRNA expression of factors regulating skeletal muscle oxidative capacity i.e., peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1alpha) and vascular endothelial growth factor (VEGF), and glycolytic capacity, i.e., phosphofructokinase (PFK), glycogen phosphorylase and synthase, hexokinase, and phosphorylase kinase alpha1, were subsequently analyzed. Grp UL showed decreased (36%) PGC-1alpha expression, increased (1.5-fold) PFK expression, and a trend toward decreased VEGF post-intervention. Grp UL+RE showed no changes. These results suggest that 5 wk unloading reduces skeletal muscle oxidative capacity and increases glycolytic enzyme activity. More importantly, only 12 bouts of high-force, low-volume resistance exercise attenuated these responses. Thus, the current resistance exercise paradigm emphasizing eccentric overload effectively counteracts unwarranted metabolic alterations induced by 5 wk unloading and may, therefore, aid in maintaining skeletal muscle integrity and endurance, and hence astronaut health and fitness during spaceflight.

  11. Paclitaxel injection concentrate for nanodispersion versus nab-paclitaxel in women with metastatic breast cancer: a multicenter, randomized, comparative phase II/III study.

    PubMed

    Jain, Minish M; Gupte, Smita U; Patil, Shekhar G; Pathak, Anand B; Deshmukh, Chetan D; Bhatt, Niraj; Haritha, Chiramana; Govind Babu, K; Bondarde, Shailesh A; Digumarti, Raghunadharao; Bajpai, Jyoti; Kumar, Ravi; Bakshi, Ashish V; Bhattacharya, Gouri Sankar; Patil, Poonam; Subramanian, Sundaram; Vaid, Ashok K; Desai, Chirag J; Khopade, Ajay; Chimote, Geetanjali; Bapsy, Poonamalle P; Bhowmik, Shravanti

    2016-02-01

    Paclitaxel is widely used in the treatment of patients with metastatic breast cancer (MBC). Formulations of paclitaxel contain surfactants and solvents or albumin derived from human blood. The use of co-solvents such as polyoxyethylated castor oil is thought to contribute to toxicity profile and hypersensitivity reactions as well as leaching of plasticizers from polyvinyl chloride bags and infusion sets. Currently, nab-paclitaxel, an albumin-bound paclitaxel in nanometer range continues to be the preferred taxane formulation used in clinic. This study (CTRI/2010/091/001116) investigated the efficacy and tolerability of a polyoxyethylated castor oil- and albumin-free formulation of paclitaxel [paclitaxel injection concentrate for nanodispersion (PICN)] compared with nab-paclitaxel in women with refractory MBC. The current study was a multicenter, open-label, parallel-group, randomized, comparative phase II/III trial evaluating the efficacy and safety of PICN (260 mg/m(2) [n = 64] and 295 mg/m(2) [n = 58] every 3 weeks) compared with nab-paclitaxel (260 mg/m(2) every 3 weeks [n = 58]) in women 18 and 70 years old with confirmed MBC. Overall response rate (ORR) was assessed with imaging every 2 cycles. An independent analysis of radiologic data was performed for evaluable patients. Progression-free survival (PFS) was a secondary efficacy measure. Independent radiologist-assessed ORRs in the evaluable population of women aged ≥70 years were 35, 49, and 43 % in the PICN 260 mg/m(2), PICN 295 mg/m(2), and nab-paclitaxel 260 mg/m(2) arms, respectively. Median PFS in the evaluable population was 23, 35, and 34 weeks in the PICN 260 mg/m(2), PICN 295 mg/m(2), and nab-paclitaxel 260 mg/m(2) arms, respectively. Adverse events occurred in similar proportions of patients across treatment arms. Hypersensitivity reactions were not frequently observed with the clinical use of PICN across the treatment cohorts. In women with metastatic breast cancer, PICN at 260 and 295 mg/m(2

  12. Cobalt(II/III) redox electrolyte in ZnO nanowire-based dye-sensitized solar cells.

    PubMed

    Fan, Jiandong; Hao, Yan; Cabot, Andreu; Johansson, Erik M J; Boschloo, Gerrit; Hagfeldt, Anders

    2013-03-01

    In this work, we explore the use of cobalt complex redox shuttles in dye sensitized solar cells (DSCs) based on ZnO nanowires (NWs). Arrays of vertically aligned ZnO NWs produced by a low-cost hydrothermal method are used to fabricate DSCs with [Co(bpy)3](2+/3+) as electrolyte. A direct comparison of the performance of [Co(bpy)3](2+/3+)-based ZnO DSC with I(-)/I3(-)-based ones demonstrates the higher suitability of the cobalt complex, both in terms of a larger open circuit voltage (VOC) and a higher photocurrent. The [Co(bpy)3](2+/3+) electrolyte results in VOC enhancements above 200 mV. This VOC increase is associated to the better match between the cobalt complex redox potential and the oxidation potential of the dye. The incident photon-to-current efficiency (IPCE) enhancement is attributed to a less competitive visible light absorption of the cobalt redox couple. Thus the present study opens new opportunities to improve energy conversion efficiency in ZnO-based DSCs.

  13. Interatomic potentials for mixed oxide and advanced nuclear fuels

    SciTech Connect

    Tiwary, Pratyush; Walle, Axel van de; Jeon, Byoungseon; Groenbech-Jensen, Niels

    2011-03-01

    We extend our recently developed interatomic potentials for UO{sub 2} to the fuel system (U,Pu,Np)O{sub 2}. We do so by fitting against an extensive database of ab initio results as well as to experimental measurements. The applicability of these interactions to a variety of mixed environments beyond the fitting domain is also assessed. The employed formalism makes these potentials applicable across all interatomic distances without the need for any ambiguous splining to the well-established short-range Ziegler-Biersack-Littmark universal pair potential. We therefore expect these to be reliable potentials for carrying out damage simulations (and molecular dynamics simulations in general) in nuclear fuels of varying compositions for all relevant atomic collision energies.

  14. Oxidation-reduction potential of semen: what is its role in the treatment of male infertility?

    PubMed Central

    Agarwal, Ashok; Roychoudhury, Shubhadeep; Bjugstad, Kimberly B.; Cho, Chak-Lam

    2016-01-01

    The diagnosis of male infertility relies largely on conventional semen analysis, and its interpretation has a profound influence on subsequent management of patients. Despite poor correlation between conventional semen parameters and male fertility potential, inclusion of advanced semen quality tests to routine male infertility workup algorithms has not been widely accepted. Oxidative stress is one of the major mediators in various etiologies of male infertility; it has deleterious effects on spermatozoa, including DNA damage. Alleviation of oxidative stress constitutes a potential treatment strategy for male infertility. Measurement of seminal oxidative stress is of crucial role in the identification and monitoring of patients who may benefit from treatments. Various tests including reactive oxygen species (ROS) assay, total antioxidant capacity (TAC) assay or malondialdehyde (MDA) assay used by different laboratories have their own drawbacks. Oxidation-reduction potential (ORP) is a measure of overall balance between oxidants and antioxidants, providing a comprehensive measure of oxidative stress. The MiOXSYS™ System is a novel technology based on a galvanostatic measure of electrons; it presents static ORP (sORP) measures with static referring to the passive or current state of activity between oxidants and antioxidants. Preliminary studies have correlated sORP to poor semen qualities. It is potentially useful in prognostication of assisted reproductive techniques outcomes, screening of antioxidants either in vivo or during IVF cycles, identification of infertile men who may benefit from treatment of oxidative stress, and monitoring of treatment success. The simplified laboratory test requiring a small amount of semen would facilitate clinical application and research in the field. In this paper, we discuss the measurement of ORP by the MiOXSYS System as a real-time assessment of seminal oxidative stress, and argue that it is a potential valuable clinical test

  15. Hydroxyethylated graphene oxide as potential carriers for methotrexate delivery

    NASA Astrophysics Data System (ADS)

    Du, Libo; Suo, Siqingaowa; Luo, Dan; Jia, Hongying; Sha, Yinlin; Liu, Yang

    2013-06-01

    In this study, we presented a simple approach to prepare hydroxyethylated graphene oxide (HE-GO) with high water solubility and physiological stability. The successful synthesis of HE-GO was confirmed by UV-Vis spectroscopy, Fourier transform infrared spectroscopy, and atomic force microscopy. The loading of anticancer drug methotrexate (MTX) onto this nanocarrier (MTX/HE-GO) was investigated. The results of in vitro drug release experiment showed that the rate of MTX release from MTX/HE-GO was pH dependent. Moreover, cell viability assay demonstrated that HE-GO loaded with MTX exhibits higher anticancer activity against human lung adenocarcinoma epithelial cell line than non-vehicle MTX.

  16. OXIDATIVE INACTIVATION OF THE PROTEASOME IN RPE: A POTENTIAL LINK BETWEEN OXIDATIVE STRESS AND UPREGULATION OF IL-8

    USDA-ARS?s Scientific Manuscript database

    Oxidative stress and inflammation are implicated in the pathogenesis of several age-related diseases. Stress-induced overproduction of inflammatory cytokines, such as interleukin-8 (IL-8), is one of the early events of inflammation. The objective of this study was to determine potential links betwee...

  17. Oxidant production from source-oriented particulate matter - Part 1: Oxidative potential using the dithiothreitol (DTT) assay

    NASA Astrophysics Data System (ADS)

    Charrier, J. G.; Richards-Henderson, N. K.; Bein, K. J.; McFall, A. S.; Wexler, A. S.; Anastasio, C.

    2014-09-01

    Recent epidemiological evidence supports the hypothesis that health effects from inhalation of ambient particulate matter (PM) are governed by more than just the mass of PM inhaled. Both specific chemical components and sources have been identified as important contributors to mortality and hospital admissions, even when these endpoints are unrelated to PM mass. Sources may cause adverse health effects via their ability to produce reactive oxygen species, possibly due to the transition metal content of the PM. Our goal is to quantify the oxidative potential of ambient particle sources collected during two seasons in Fresno, CA using the dithiothreitol (DTT) assay. We collected PM from different sources or source combinations into different ChemVol (CV) samplers in real time using a novel source-oriented sampling technique based on single particle mass spectrometry. We segregated the particles from each source-oriented mixture into two size fractions - ultrafine (Dp ≤ 0.17 μm) and submicron fine (0.17 μm ≤ Dp ≤ 1.0 μm) - and measured metals and the rate of DTT loss in each PM extract. We find that the mass-normalized oxidative potential of different sources varies by up to a actor of 8 and that submicron fine PM typically has a larger mass-normalized oxidative potential than ultrafine PM from the same source. Vehicular Emissions, Regional Source Mix, Commute Hours, Daytime Mixed Layer and Nighttime Inversion sources exhibit the highest mass-normalized oxidative potential. When we apportion the volume-normalized oxidative potential, which also accounts for the source's prevalence, cooking sources account for 18-29% of the total DTT loss while mobile (traffic) sources account for 16-28%. When we apportion DTT activity for total PM sampled to specific chemical compounds, soluble copper accounts for roughly 50% of total air-volume-normalized oxidative potential, soluble manganese accounts for 20%, and other unknown species, likely including quinones and other

  18. Effects of Potential and Mechanical Stimulation on Oxidation of Tantalum During Electrochemical Mechanical Polishing

    NASA Astrophysics Data System (ADS)

    Gao, F.; Liang, Hong

    2012-03-01

    Metal oxidation under stress plays a significant role in many industrial applications, particularly in chemical mechanical polishing (CMP). Here we report effects of mechanical stimulation on tantalum (Ta) oxidation during CMP. A tantalum surface was polished at various anodic potentials and under different mechanical forces. A potentiostat was used to measure the anodic reaction current during electrochemical mechanical polishing (ECMP). The material removal rate (MRR) measured using atomic force microscopy (AFM) was compared with that calculated using Faraday's law. Relationship was linked (or established) between the anodic potential and a mechanical force. The MRR was a second-order polynomial function of potential at constant mechanical force, followed by a logarithmic function. It was found that more suboxides were present at extreme potentials (low and high), while substantial pentoxide was generated under intermediate potentials. A model is proposed to explain the oxidation process of Ta during ECMP. The oxidation of Ta was a function of the anodic potential and mechanical force. The ex situ method used in this study fulfilled the in situ observation on Ta oxidation in polishing. Additionally, this technique can be used to investigate oxidation of other metals.

  19. Identifying Criegee Intermediates As Potential Oxidants In The Troposphere

    NASA Astrophysics Data System (ADS)

    Novelli, A.; Hens, K.; Tatum Ernest, C.; Martinez, M.; Nölscher, A. C.; Sinha, V.; Paasonen, P.; Petäjä, T.; Sipilä, M.; Elste, T.; Plass-Duelmer, C.; Kubistin, D.; Phillips, G. J.; Williams, J.; Vereecken, L.; Lelieveld, J.; Harder, H.

    2015-12-01

    Criegee intermediates (CI) are formed during the ozonolysis of unsaturated compounds and have been intensively studied in the last few years due to their possible role as oxidants in the troposphere. Stabilised CI (SCI) are now known to react very rapidly, k(298 K) = 10-12 to 10-10 cm3 molecule-1 s-1, with a large number of trace gases (SO2, NO2, organic acids, water dimers). An assessment of their effective oxidative capacity remain challenging as, CI chemistry is complex, it spans a large range of rate coefficients for different SCI conformers reacting with water dimers and trace gases, and in addition, no reliable measurement technique able to detect ambient SCI concentrations is currently available. In this study, we examine the extensive dataset from the HUMPPA-COPEC 2010 and the HOPE 2012 field campaigns, aided by literature data, to estimate the abundance of SCI in the lower troposphere. The budget of SCI is analyzed using four different approaches: 1) based on an observed yet unexplained H2SO4 production; 2) from the measured concentrations of unsaturated volatile organic compounds (VOC); 3) from OH reactivity measurements; 4) from the unexplained production rate of OH. A SCI concentration range between 5 x 103 and 2 x 106 molecule cm-3 is calculated for the two environments. The weighted mean estimate of the SCI concentration over the boreal forest of ~ 5 x 104 molecules cm-3 implies a significant impact on the conversion of SO2 into H2SO4. In addition, we present measurements obtained using our inlet pre-injector laser-induced fluorescence assay by gas expansion technique (IPI-LIF-FAGE) for the above-mentioned campaigns. A recent laboratory study performed with the same instrumental setup showed that the IPI-LIF-FAGE system is sensitive to the detection of the OH formed from unimolecular decomposition of SCI. In order to investigate the applicability of the laboratory findings to the ambient data, measurement of the background OH (OHbg), the signal

  20. Excitonic giant-dipole potentials in cuprous oxide

    NASA Astrophysics Data System (ADS)

    Kurz, Markus; Grünwald, Peter; Scheel, Stefan

    2017-06-01

    In this paper we predict the existence of a novel species of Wannier excitons when exposed to crossed electric and magnetic fields. In particular, we present a theory of giant-dipole excitons in Cu2O in crossed fields. Within our theoretical approach we perform a pseudoseparation of the center-of-mass motion for the field-dressed excitonic species, thereby obtaining an effective single-particle Hamiltonian for the relative motion. For arbitrary gauge fields we exactly separate the gauge-dependent kinetic-energy terms from the effective single-particle interaction potential. Depending on the applied field strengths and the specific field orientation, the potential for the relative motion of electron and hole exhibits an outer well at spatial separations up to several micrometers and depths up to 380 μ eV , leading to possible permanent excitonic electric dipole moments of around 3 ×106 D.

  1. Potentially toxic element release by fenton oxidation of sewage sludge.

    PubMed

    Andrews, J P; Asaadi, M; Clarke, B; Ouki, S

    2006-01-01

    The presence, in sewage sludge, of excess levels of the potentially toxic elements (PTE) copper, zinc, chromium, cadmium, nickel, lead and mercury, could impact on our ability to recycle these residues in the future. Far stricter limits on the levels of PTEs are likely in proposed legislation. A method involving the dosing of Fenton's reagent, a mixture of ferrous iron and hydrogen peroxide, under acidic conditions was evaluated for its potential to reduce metal levels. The [Fe]:[H2O2] (w/w) ratio was found to give a good indication of the percentage copper and zinc elution obtainable. Sites with no iron dosing as part of wastewater treatment required extra iron to be added in order to initiate the Fenton's reaction. A significant reduction, in excess of 70%, of the copper and zinc was eluted from both raw primary and activated sludge solid fractions. Cadmium and nickel could be reduced to below detection limits but elution of mercury, lead and chromium was less than 40%. The iron catalyst concentration was found to be a crucial parameter. This process has the potential to reduce the heavy metal content of the sludge and allow the recycling of sludge to continue in a sustainable manner.

  2. Structural, EPR, and Mössbauer characterization of (μ-alkoxo)(μ-carboxylato)diiron(II,III) model complexes for the active sites of mixed-valent diiron enzymes.

    PubMed

    Li, Feifei; Chakrabarti, Mrinmoy; Dong, Yanhong; Kauffmann, Karl; Bominaar, Emile L; Münck, Eckard; Que, Lawrence

    2012-03-05

    To obtain structural and spectroscopic models for the diiron(II,III) centers in the active sites of diiron enzymes, the (μ-alkoxo)(μ-carboxylato)diiron(II,III) complexes [Fe(II)Fe(III)(N-Et-HPTB)(O(2)CPh)(NCCH(3))(2)](ClO(4))(3) (1) and [Fe(II)Fe(III)(N-Et-HPTB)(O(2)CPh)(Cl)(HOCH(3))](ClO(4))(2) (2) (N-Et-HPTB = N,N,N',N'-tetrakis(2-(1-ethyl-benzimidazolylmethyl))-2-hydroxy-1,3-diaminopropane) have been prepared and characterized by X-ray crystallography, UV-visible absorption, EPR, and Mössbauer spectroscopies. Fe1-Fe2 separations are 3.60 and 3.63 Å, and Fe1-O1-Fe2 bond angles are 128.0° and 129.4° for 1 and 2, respectively. Mössbauer and EPR studies of 1 show that the Fe(III) (S(A) = 5/2) and Fe(II) (S(B) = 2) sites are antiferromagnetically coupled to yield a ground state with S = 1/2 (g= 1.75, 1.88, 1.96); Mössbauer analysis of solid 1 yields J = 22.5 ± 2 cm(-1) for the exchange coupling constant (H = JS(A)·S(B) convention). In addition to the S = 1/2 ground-state spectrum of 1, the EPR signal for the S = 3/2 excited state of the spin ladder can also be observed, the first time such a signal has been detected for an antiferromagnetically coupled diiron(II,III) complex. The anisotropy of the (57)Fe magnetic hyperfine interactions at the Fe(III) site is larger than normally observed in mononuclear complexes and arises from admixing S > 1/2 excited states into the S = 1/2 ground state by zero-field splittings at the two Fe sites. Analysis of the "D/J" mixing has allowed us to extract the zero-field splitting parameters, local g values, and magnetic hyperfine structural parameters for the individual Fe sites. The methodology developed and followed in this analysis is presented in detail. The spin Hamiltonian parameters of 1 are related to the molecular structure with the help of DFT calculations. Contrary to what was assumed in previous studies, our analysis demonstrates that the deviations of the g values from the free electron value (g = 2) for the

  3. Lessons learnt from Volcanoes' Night I-II-III - a Marie Curie Researchers' Night project series dedicated to geosciences

    NASA Astrophysics Data System (ADS)

    Cseko, Adrienn; Bodo, Balazs; Ortega Rodriguez, Ariadna

    2017-04-01

    European Researchers' Nights (ERNs) are a pan-European series of events funded by the European Commission, organised on the last Friday of every September since 2005. ERNs mobilise scientific, academic and research organisations with the aim of giving the public the opportunity to meet researchers in an informal setting. The overall objective of ERNs is to achieve better awareness among the general public concerning the importance of science in everyday life and to combat stereotypes about researchers. The longer-term strategic objective of ERNs is to encourage young people to embark on a scientific career. Volcanoes' Night I-II-III has been an ERN project series funded by the EC FP7 and H2020 programmes between 2012-2015 (EC contract No. 316558, 610050, 633310, www.nochedevolcanes.es). The concept of Volcanoes' Night was created by researchers from the Canary Islands, Spain, where both the researchers and the public live in the close vicinity of volcanoes. The objective of the project was to use volcanoes as a background against which the role of geoscientists could be explained to the public. The scope of Volcanoes' Night was exclusively dedicated to geoscience, and in this respect it stands out among all other ERN projects, which are always more general in scope. During its four years of EC funding, the geographical coverage of Volcanoes' Night expanded substantially from a single location in 2012 (Fuencaliente de La Palma, Spain) to a dozen locations in 2015, mobilising multiple scientific organisations, researchers, and public authorities for engagement with the public. The last EC-funded project, Volcanoes' Night III, which was organised in 2014 and 2015, engaged approximately 21,000 visitors through its outreach activities, which included experiments, science cafés, volcano movies, My Day presentations, excursions, science workshops and more. The impact of the project was carefully assessed via surveys and social studies during its lifetime, and an Impact

  4. Average chemical properties and potential formation pathways of highly oxidized organic aerosol.

    PubMed

    Daumit, Kelly E; Kessler, Sean H; Kroll, Jesse H

    2013-01-01

    Measurements of ambient organic aerosol indicate that a substantial fraction is highly oxidized and low in volatility, but this fraction is generally not reproduced well in either laboratory studies or models. Here we describe a new approach for constraining the viable precursors and formation pathways of highly oxidized organic aerosol, by starting with the oxidized product and considering the possible reverse reactions, using a set of simple chemical rules. The focus of this work is low-volatility oxidized organic aerosol (LV-OOA), determined from factor analysis of aerosol mass spectrometer data. The elemental composition and volatility of the aerosol enable the determination of its position in a three-dimensional chemical space (defined by H/C, O/C, and carbon number) and thus its average chemical formula. Consideration of possible back-reactions then defines the movement taken through this chemical space, constraining potential reaction pathways and precursors. This approach is taken for two highly oxidized aerosol types, an average of LV-OOA factors from ten field campaigns (average formula C10.5H13.4O7.3), and extremely oxidized LV-OOA (from Mexico City, average formula C10H12.1O8.4). Results suggest that potential formation pathways include functionalization reactions that add multiple functional groups per oxidation step, oligomerization of highly oxidized precursors, and, in some cases, fragmentation reactions that involve the loss of small, reduced fragments.

  5. Alginate nanoparticles protect ferrous from oxidation: Potential iron delivery system.

    PubMed

    Katuwavila, Nuwanthi P; Perera, A D L C; Dahanayake, Damayanthi; Karunaratne, V; Amaratunga, Gehan A J; Karunaratne, D Nedra

    2016-11-20

    A novel, efficient delivery system for iron (Fe(2+)) was developed using the alginate biopolymer. Iron loaded alginate nanoparticles were synthesized by a controlled ionic gelation method and was characterized with respect to particle size, zeta potential, morphology and encapsulation efficiency. Successful loading was confirmed with Fourier Transform Infrared spectroscopy and Thermogravimetric Analysis. Electron energy loss spectroscopy study corroborated the loading of ferrous into the alginate nanoparticles. Iron encapsulation (70%) was optimized at 0.06% Fe (w/v) leading to the formation of iron loaded alginate nanoparticles with a size range of 15-30nm and with a negative zeta potential (-38mV). The in vitro release studies showed a prolonged release profile for 96h. Release of iron was around 65-70% at pH of 6 and 7.4 whereas it was less than 20% at pH 2.The initial burst release upto 8h followed zero order kinetics at all three pH values. All the release profiles beyond 8h best fitted the Korsmeyer-Peppas model of diffusion. Non Fickian diffusion was observed at pH 6 and 7.4 while at pH 2 Fickian diffusion was observed. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Effects of Muscle-Specific Oxidative Stress on Cytochrome c Release and Oxidation-Reduction Potential Properties.

    PubMed

    Ke, Yiling; Mitacek, Rachel M; Abraham, Anupam; Mafi, Gretchen G; VanOverbeke, Deborah L; DeSilva, Udaya; Ramanathan, Ranjith

    2017-09-06

    Mitochondria play a significant role in beef color. However, the role of oxidative stress in cytochrome c release and mitochondrial degradation is not clear. The objective was to determine the effects of display time on cytochrome c content and oxidation-reduction potential (ORP) of beef longissimus lumborum (LL) and psoas major (PM) muscles. PM discolored by day 3 compared with LL. On day 0, mitochondrial content and mitochondrial oxygen consumption were greater in PM than LL. However, mitochondrial content and oxygen consumption were lower (P < 0.05) in PM than LL by day 7. Conversely, cytochrome c content in sarcoplasm was greater on days 3 and 7 for PM than LL. There were no significant differences in ORP for LL during display, but ORP increased for PM on day 3 when compared with day 0. The results suggest that muscle-specific oxidative stress can affect cytochrome c release and ORP changes.

  7. Cytokine serum levels in patients with cervical intraepithelial neoplasia grade II-III treated with intralesional interferon-α 2b.

    PubMed

    Misson, Daniela Ribeiro; Abdalla, Douglas Reis; Borges, Ariana Melo; Shimba, Denis Sakamoto; Adad, Sheila Jorge; Michelin, Márcia Antoniazi; Murta, Eddie Fernando Candido

    2011-01-01

    Cervical intraepithelial neoplasia (CIN) grade II-III is being diagnosed in younger women and, because of the reproductive age range for women and the habits associated with a modern lifestyle, is now affecting a broad age range. Surgical treatment for CIN has been associated with premature amenorrhea, low birth weight, and premature labor and birth. It is therefore imperative to develop clinical treatments for CIN, such as conservative treatment with interferons. The object of the present study was to evaluate the behavior of cytokines (IFN- g, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, TNF-α, TGF β) in the serum of patients with an initial diagnosis of CIN II-III. Ten patients with CIN-CIN II (60%, n = 6) and CIN III (40%, n = 4), 23 to 51 years of age and who had not received any prior treatments, were evaluated. The patients were given 3 million/UI (per cm2 of colposcopic lesion) of human recombinant IFN-α 2b by intralesional administration (18 applications on alternate days). Before treatment, in the 6th, 12th, and 18th applications, blood was collected from the patients for cytokine analysis using ELISA. Half of the patients had a good pathologic response; the other half, all of whom were smokers, had therapeutic failure. The average concentration of IL-12 (pg/ml) in the serum of patients who responded well to therapy was elevated from the 12th and 18th application of IFN-α 2b compared to patients who experienced therapeutic failure: 1804.0 ± 1020 vs 391.2 ± 722.3 and 1738.0 ± 2426.0 vs 448.5 ± 407.2, respectively, P <0.05. CIN II-III treated with intralesional IFN-α 2b achieved a good response in non-smoking patients and was associated with an increase in IL-12 serum levels.

  8. Near infrared spectroscopy combined with multivariate analysis for monitoring the ethanol precipitation process of fraction I + II + III supernatant in human albumin separation

    NASA Astrophysics Data System (ADS)

    Li, Can; Wang, Fei; Zang, Lixuan; Zang, Hengchang; Alcalà, Manel; Nie, Lei; Wang, Mingyu; Li, Lian

    2017-03-01

    Nowadays, as a powerful process analytical tool, near infrared spectroscopy (NIRS) has been widely applied in process monitoring. In present work, NIRS combined with multivariate analysis was used to monitor the ethanol precipitation process of fraction I + II + III (FI + II + III) supernatant in human albumin (HA) separation to achieve qualitative and quantitative monitoring at the same time and assure the product's quality. First, a qualitative model was established by using principal component analysis (PCA) with 6 of 8 normal batches samples, and evaluated by the remaining 2 normal batches and 3 abnormal batches. The results showed that the first principal component (PC1) score chart could be successfully used for fault detection and diagnosis. Then, two quantitative models were built with 6 of 8 normal batches to determine the content of the total protein (TP) and HA separately by using partial least squares regression (PLS-R) strategy, and the models were validated by 2 remaining normal batches. The determination coefficient of validation (Rp2), root mean square error of cross validation (RMSECV), root mean square error of prediction (RMSEP) and ratio of performance deviation (RPD) were 0.975, 0.501 g/L, 0.465 g/L and 5.57 for TP, and 0.969, 0.530 g/L, 0.341 g/L and 5.47 for HA, respectively. The results showed that the established models could give a rapid and accurate measurement of the content of TP and HA. The results of this study indicated that NIRS is an effective tool and could be successfully used for qualitative and quantitative monitoring the ethanol precipitation process of FI + II + III supernatant simultaneously. This research has significant reference value for assuring the quality and improving the recovery ratio of HA in industrialization scale by using NIRS.

  9. Phase II Study of Chemoradiotherapy With 5-Fluorouracil and Cisplatin for Stage II-III Esophageal Squamous Cell Carcinoma: JCOG Trial (JCOG 9906)

    SciTech Connect

    Kato, Ken; Muro, Kei; Minashi, Keiko; Ohtsu, Atsushi; Ishikura, Satoshi; Boku, Narikazu; Takiuchi, Hiroya; Komatsu, Yoshito; Miyata, Yoshinori; Fukuda, Haruhiko

    2011-11-01

    Purpose: In this Phase II study, we evaluated the efficacy and toxicity of chemoradiotherapy (CRT) with cisplatin (CDDP) and 5-fluorouracil (5-FU) for Stage II-III esophageal squamous cell carcinoma (ESCC). Patients and Methods: Patients with clinical Stage II-III (T1N1M0 or T2-3N0-1M0) thoracic ESCC were enrolled between April 2000 and March 2002. Chemotherapy comprised two courses of protracted infusion of 5-FU (400 mg/m{sup 2}/day) on Days 1-5 and 8-12, and 2-h infusion of CDDP (40 mg/m{sup 2}) on Days 1 and 8; this regimen was repeated every 5 weeks. Concurrent radiotherapy involved 60-Gy irradiation (30 fractions) for 8 weeks with a 2-week break. Responders received two courses of 5-FU (800 mg/m{sup 2}/day) on Days 1-5 and CDDP (80 mg/m{sup 2}) on Day 1. Final analysis was conducted in March 2007. Survival and late toxicities were monitored for 5 years. Results: The characteristics of the 76 patients enrolled were as follows: median age, 61 years; male/female, 68/8; performance status 0/1, 59/17 patients; Stage IIA/IIB/III, 26/12/38 patients. Of the 74 eligible patients, 46 (62.2%) achieved complete response. Median survival time was 29 months, with 3- and 5-year survival rates of 44.7% and 36.8%, respectively. Acute toxicities included Grade 3/4 esophagitis (17%), nausea (17%), hyponatremia (16%), and infection without neutropenia (12%). Late toxicities comprised Grade 3/4 esophagitis (13%), pericardial (16%) and pleural (9%) effusion, and radiation pneumonitis (4%), causing 4 deaths. Conclusions: CRT is effective for Stage II-III ESCC with manageable acute toxicities and can provide a nonsurgical treatment option. However, further improvement is required for reduction in late toxicity.

  10. Dose-Response Relationship between Radiation Dose and Loco-regional Control in Patients with Stage II-III Esophageal Cancer Treated with Definitive Chemoradiotherapy.

    PubMed

    Kim, Hyun Ju; Suh, Yang-Gun; Lee, Yong Chan; Lee, Sang Kil; Shin, Sung Kwan; Cho, Byung Chul; Lee, Chang Geol

    2017-07-01

    The correlation between radiation dose and loco-regional control (LRC) was evaluated in patients with stage II-III esophageal cancer treated with definitive concurrent chemoradiotherapy (CRT). Medical records of 236 stage II-III esophageal cancer patients treated with definitive CRT at Yonsei Cancer Center between 1994 and 2013 were retrospectively reviewed. Among these, 120 received a radiation dose of < 60 Gy (standard-dose group), while 116 received ≥ 60 Gy (high-dose group). The median doses of radiation in the standard- and high-dose groups were 50.4 and 63 Gy, respectively. Concurrent 5-fluorouracil/cisplatin chemotherapy was administered to most patients. There were no differences in patient characteristics between the two groups except for high Karnofsky performance status and lower-thoracic lesions being more prevalent in the standard-dose group. The median progression-free survival (PFS) and overall survival (OS) times were 13.2 months and 26.2 months, respectively. Patients in the high-dose group had significantly better 2-year LRC (69.1% vs. 50.3%, p=0.002), median PFS (16.7 months vs. 11.7 months, p=0.029), and median OS (35.1 months vs. 22.3 months, p=0.043). Additionally, LRC exhibited a dose-response relationship and the complete response rate was significantly higher in the high-dose group (p=0.006). There were no significant differences in treatment-related toxicities between the groups. A higher radiation dose (> 60 Gy) is associated with increased LRC, PFS, and OS in patients with stage II-III esophageal cancer treated with definitive CRT.

  11. Strychnine-sensitive glycine receptors on pyramidal neurons in layers II/III of the mouse prefrontal cortex are tonically activated.

    PubMed

    Salling, Michael C; Harrison, Neil L

    2014-09-01

    Processing of signals within the cerebral cortex requires integration of synaptic inputs and a coordination between excitatory and inhibitory neurotransmission. In addition to the classic form of synaptic inhibition, another important mechanism that can regulate neuronal excitability is tonic inhibition via sustained activation of receptors by ambient levels of inhibitory neurotransmitter, usually GABA. The purpose of this study was to determine whether this occurs in layer II/III pyramidal neurons (PNs) in the prelimbic region of the mouse medial prefrontal cortex (mPFC). We found that these neurons respond to exogenous GABA and to the α4δ-containing GABAA receptor (GABA(A)R)-selective agonist gaboxadol, consistent with the presence of extrasynaptic GABA(A)R populations. Spontaneous and miniature synaptic currents were blocked by the GABA(A)R antagonist gabazine and had fast decay kinetics, consistent with typical synaptic GABA(A)Rs. Very few layer II/III neurons showed a baseline current shift in response to gabazine, but almost all showed a current shift (15-25 pA) in response to picrotoxin. In addition to being a noncompetitive antagonist at GABA(A)Rs, picrotoxin also blocks homomeric glycine receptors (GlyRs). Application of the GlyR antagonist strychnine caused a modest but consistent shift (∼15 pA) in membrane current, without affecting spontaneous synaptic events, consistent with the tonic activation of GlyRs. Further investigation showed that these neurons respond in a concentration-dependent manner to glycine and taurine. Inhibition of glycine transporter 1 (GlyT1) with sarcosine resulted in an inward current and an increase of the strychnine-sensitive current. Our data demonstrate the existence of functional GlyRs in layer II/III of the mPFC and a role for these receptors in tonic inhibition that can have an important influence on mPFC excitability and signal processing. Copyright © 2014 the American Physiological Society.

  12. Near infrared spectroscopy combined with multivariate analysis for monitoring the ethanol precipitation process of fraction I+II+III supernatant in human albumin separation.

    PubMed

    Li, Can; Wang, Fei; Zang, Lixuan; Zang, Hengchang; Alcalà, Manel; Nie, Lei; Wang, Mingyu; Li, Lian

    2017-03-15

    Nowadays, as a powerful process analytical tool, near infrared spectroscopy (NIRS) has been widely applied in process monitoring. In present work, NIRS combined with multivariate analysis was used to monitor the ethanol precipitation process of fraction I+II+III (FI+II+III) supernatant in human albumin (HA) separation to achieve qualitative and quantitative monitoring at the same time and assure the product's quality. First, a qualitative model was established by using principal component analysis (PCA) with 6 of 8 normal batches samples, and evaluated by the remaining 2 normal batches and 3 abnormal batches. The results showed that the first principal component (PC1) score chart could be successfully used for fault detection and diagnosis. Then, two quantitative models were built with 6 of 8 normal batches to determine the content of the total protein (TP) and HA separately by using partial least squares regression (PLS-R) strategy, and the models were validated by 2 remaining normal batches. The determination coefficient of validation (Rp(2)), root mean square error of cross validation (RMSECV), root mean square error of prediction (RMSEP) and ratio of performance deviation (RPD) were 0.975, 0.501g/L, 0.465g/L and 5.57 for TP, and 0.969, 0.530g/L, 0.341g/L and 5.47 for HA, respectively. The results showed that the established models could give a rapid and accurate measurement of the content of TP and HA. The results of this study indicated that NIRS is an effective tool and could be successfully used for qualitative and quantitative monitoring the ethanol precipitation process of FI+II+III supernatant simultaneously. This research has significant reference value for assuring the quality and improving the recovery ratio of HA in industrialization scale by using NIRS.

  13. A decacobalt(ii) cluster with triple-sandwich structure obtained by partial reductive hydrolysis of a pentacobalt(ii/iii) Weakley-type polyoxometalate.

    PubMed

    Duan, Yan; Clemente-Juan, Juan M; Fierro, José L G; Giménez-Saiz, Carlos; Coronado, Eugenio

    2016-11-03

    Partial reductive hydrolysis of a penta-Co(II/III) cluster [Co(H2O)2(Co(III)W9O34)(PW9O34)](12-) (1) leads to the formation of [Co2{Co3(H2O)(Co(OH)2W7O26)(PW9O34)}2](22-) (2). This polyoxometalate is made up of two capping [PW9O34](9-) units and two bridging [W7O26](10-) units that assemble to encapsulate a novel deca-Co(II) cluster core comprising octahedral and tetrahedral Co(II) ions.

  14. Reductive Trapping of [(OC)5 W-W(CO)5 ](2-) in a Mixed-Valent Sm(II/III) Calix[4]pyrrolide Sandwich.

    PubMed

    Deacon, Glen B; Guo, Zhifang; Junk, Peter C; Wang, Jun

    2017-07-10

    Reduction of tungsten hexacarbonyl by the divalent samarium(II) complex [Sm2 (N4 Et8 )(thf)4 ] ((N4 Et8 )(4-) =meso-octaethylcalix[4]pyrrolide) in toluene at ambient temperature gave the remarkable heteronuclear mixed-valent samarium(II/III)/tungsten complex [{(thf)2 Sm(II) (N4 Et8 )Sm(III) (thf)}2 {(μ-OC)2 W2 (CO)8 }], which features the trapping of a rare [W2 (CO)10 ](2-) anion with an unsupported W-W bond. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Incidence and specificity of antibodies to types I, II, III, IV, and V collagen in rheumatoid arthritis and other rheumatic diseases as measured by 125I-radioimmunoassay

    SciTech Connect

    Stuart, J.M.; Huffstutter, E.H.; Townes, A.S.; Kang, A.H.

    1983-07-01

    Antibodies to human native and denatured types I, II, III, IV, and V collagens were measured using 125I-radioimmunoassay. Mean levels of binding by sera from 30 rheumatoid arthritis patients were significantly higher than those from 20 normal subjects against all of the collagens tested. The relative antibody concentration was higher in synovial fluid than in simultaneously obtained serum. Many patients with gout or various other rheumatic diseases also had detectable anticollagen antibodies. With a few notable exceptions, the majority of the reactivity detected in all patient groups was directed against covalent structural determinants present on all of the denatured collagens, suggesting a secondary reaction to tissue injury.

  16. Angiotensin Mediated Oxidative Stress and Neuroprotective Potential of Antioxidants and AT1 Receptor Blockers.

    PubMed

    Prusty, Shakti Ketan; Sahu, Pratap Kumar; Subudhi, Bharat Bhusan

    2017-01-01

    Oxidative stress in brain underlies the major neurological disorders including Alzheimer's disease (AD) and Parkinson's disease (PD). Peripherally, Angiotensin-II is a major effector of inflammation. Identification of its capacity to access brain during hypertension, as well as location of central renin angiotensin system have led to its recognition as the major effector of oxidative stress in brain. Clinical uses of antioxidants to antagonize this oxidative stress have mostly failed. In this scenario, AT1 blockers have been investigated to prevent neurodegeneration. Although it has shown promise, clinical efficacy is limited to few drugs including telmisartan mainly due to the poor brain availability of others. In this review we aim to analyze the potential of antioxidants to reduce oxidative stress in brain. We have given critical analysis of the approaches for re-purposing of AT1 blockers against oxidative stress induced neurodegeneration. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  17. Plasma electrolytic oxidation coatings on γTiAl alloy for potential biomedical applications.

    PubMed

    Lara Rodriguez, L; Sundaram, P A; Rosim-Fachini, E; Padovani, A M; Diffoot-Carlo, N

    2014-07-01

    In an attempt to enhance the potential of gamma titanium aluminide intermetallic alloy as a biomaterial, its surface characteristics were successfully modified using a calcium and phosphorous rich electrolyte through the application of plasma electrolytic oxidation. Scanning electron microscopy and atomic force microscopy were used to characterize the morphology and topographical features of the resulting coating while X-ray diffraction and energy dispersive spectroscopy were used to determine the surface oxide composition. The mechanical properties of the surface coating were characterized by nanoindentation studies. The results observed show the formation of a submicron scale porous structure and a concomitant increase in the surface roughness. The surface oxide was composed of rutile and anatase phases. Composition gradients of Ca and P were also present which can possibly enhance the biomaterial application potential of this treated surface. Nanoindentation measurements indicate the formation of a fairly compact oxide during the process.

  18. Potential Impacts of two SO2 oxidation pathways on regional sulfate concentrations: acqueous-hase oxidation by NO2 and gas-phase oxidation by Stabilized Criegee Intermediates

    EPA Science Inventory

    We examine the potential impacts of two additional sulfate production pathways using the Community Multiscale Air Quality modeling system. First we evaluate the impact of the aqueous-phase oxidation of S(IV) by nitrogen dioxide using two published rate constants, differing by 1-2...

  19. Potential Impacts of two SO2 oxidation pathways on regional sulfate concentrations: acqueous-hase oxidation by NO2 and gas-phase oxidation by Stabilized Criegee Intermediates

    EPA Science Inventory

    We examine the potential impacts of two additional sulfate production pathways using the Community Multiscale Air Quality modeling system. First we evaluate the impact of the aqueous-phase oxidation of S(IV) by nitrogen dioxide using two published rate constants, differing by 1-2...

  20. Attenuation of Combined Nickel(II) Oxide and Manganese(II, III) Oxide Nanoparticles’ Adverse Effects with a Complex of Bioprotectors

    PubMed Central

    Minigalieva, Ilzira A.; Katsnelson, Boris A.; Privalova, Larisa I.; Sutunkova, Marina P.; Gurvich, Vladimir B.; Shur, Vladimir Y.; Shishkina, Ekaterina V.; Valamina, Irene E.; Makeyev, Oleg H.; Panov, Vladimir G.; Varaksin, Anatoly N.; Grigoryeva, Ekaterina V.; Meshtcheryakova, Ekaterina Y.

    2015-01-01

    Stable suspensions of NiO and Mn3O4 nanoparticles (NPs) with a mean (±s.d.) diameter of 16.7 ± 8.2 and 18.4 ± 5.4 nm, respectively, purposefully prepared by laser ablation of 99.99% pure nickel or manganese in de-ionized water, were repeatedly injected intraperitoneally (IP) to rats at a dose of 2.5 mg/kg 3 times a week up to 18 injections, either alone or in combination. A group of rats was injected with this combination with the background oral administration of a “bio-protective complex” (BPC) comprising pectin, vitamins A, C, E, glutamate, glycine, N-acetylcysteine, selenium, iodide and omega-3 PUFA, this composition having been chosen based on mechanistic considerations and previous experience. After the termination of injections, many functional and biochemical indices and histopathological features (with morphometric assessment) of the liver, spleen, kidneys and brain were evaluated for signs of toxicity. The Ni and Mn content of these organs was measured with the help of the atomic emission and electron paramagnetic resonance spectroscopies. We obtained blood leukocytes for performing the RAPD (Random Amplified Polymorphic DNA) test. Although both metallic NPs proved adversely bio-active in many respects considered in this study, Mn3O4-NPs were somewhat more noxious than NiO-NPs as concerns most of the non-specific toxicity manifestations and they induced more marked damage to neurons in the striatum and the hippocampus, which may be considered an experimental correlate of the manganese-induced Parkinsonism. The comparative solubility of the Mn3O4-NPs and NiO-NPs in a biological medium is discussed as one of the factors underlying the difference in their toxicokinetics and toxicities. The BPC has attenuated both the organ-systemic toxicity and the genotoxicity of Mn3O4-NPs in combination with NiO-NPs. PMID:26393577

  1. The effect of coal bed dewatering and partial oxidation on biogenic methane potential

    USGS Publications Warehouse

    Jones, Elizabeth J.P.; Harris, Steve H.; Barnhart, Elliott P.; Orem, William H.; Clark, Arthur C.; Corum, Margo D.; Kirshtein, Julie D.; Varonka, Matthew S.; Voytek, Mary A.

    2013-01-01

    Coal formation dewatering at a site in the Powder River Basin was associated with enhanced potential for secondary biogenic methane determined by using a bioassay. We hypothesized that dewatering can stimulate microbial activity and increase the bioavailability of coal. We analyzed one dewatered and two water-saturated coals to examine possible ways in which dewatering influences coal bed natural gas biogenesis by looking at differences with respect to the native coal microbial community, coal-methane organic intermediates, and residual coal oxidation potential. Microbial biomass did not increase in response to dewatering. Small Subunit rRNA sequences retrieved from all coals sampled represented members from genera known to be aerobic, anaerobic and facultatively anaerobic. A Bray Curtis similarity analysis indicated that the microbial communities in water-saturated coals were more similar to each other than to the dewatered coal, suggesting an effect of dewatering. There was a higher incidence of long chain and volatile fatty acid intermediates in incubations of the dewatered coal compared to the water-saturated coals, and this could either be due to differences in microbial enzymatic activities or to chemical oxidation of the coal associated with O2 exposure. Dilute H2O2 treatment of two fractions of structural coal (kerogen and bitumen + kerogen) was used as a proxy for chemical oxidation by O2. The dewatered coal had a low residual oxidation potential compared to the water-saturated coals. Oxidation with 5% H2O2 did increase the bioavailability of structural coal, and the increase in residual oxidation potential in the water saturated coals was approximately equivalent to the higher methanogenic potential measured in the dewatered coal. Evidence from this study supports the idea that coal bed dewatering could stimulate biogenic methanogenesis through partial oxidation of the structural organics in coal once anaerobic conditions are restored.

  2. Oxidative Stress in Ischemic Brain Damage: Mechanisms of Cell Death and Potential Molecular Targets for Neuroprotection

    PubMed Central

    Chen, Hai; Yoshioka, Hideyuki; Kim, Gab Seok; Jung, Joo Eun; Okami, Nobuya; Sakata, Hiroyuki; Maier, Carolina M.; Narasimhan, Purnima; Goeders, Christina E.

    2011-01-01

    Abstract Significant amounts of oxygen free radicals (oxidants) are generated during cerebral ischemia/reperfusion, and oxidative stress plays an important role in brain damage after stroke. In addition to oxidizing macromolecules, leading to cell injury, oxidants are also involved in cell death/survival signal pathways and cause mitochondrial dysfunction. Experimental data from laboratory animals that either overexpress (transgenic) or are deficient in (knock-out) antioxidant proteins, mainly superoxide dismutase, have provided strong evidence of the role of oxidative stress in ischemic brain damage. In addition to mitochondria, recent reports demonstrate that NADPH oxidase (NOX), an important pro-oxidant enzyme, is also involved in the generation of oxidants in the brain after stroke. Inhibition of NOX is neuroprotective against cerebral ischemia. We propose that superoxide dismutase and NOX activity in the brain is a major determinant for ischemic damage/repair and that these major anti- and pro-oxidant enzymes are potential endogenous molecular targets for stroke therapy. Antioxid. Redox Signal. 14, 1505–1517. PMID:20812869

  3. Thermodynamics of axial substitution and kinetics of reactions with amino acids for the paddlewheel complex tetrakis(acetato)chloridodiruthenium(II,III).

    PubMed

    Santos, Rodrigo L S R; van Eldik, Rudi; de Oliveira Silva, Denise

    2012-06-18

    The known paddlewheel, tetrakis(acetato)chloridodiruthenium(II,III), offers a versatile synthetic route to a novel class of antitumor diruthenium(II,III) metallo drugs, where the equatorial ligands are nonsteroidal anti-inflammatory carboxylates. This complex was studied here as a soluble starting prototype model for antitumor analogues to elucidate the reactivity of the [Ru(2)(CH(3)COO)(4)](+) framework. Thermodynamic studies on equilibration reactions for axial substitution of water by chloride and kinetic studies on reactions of the diaqua complexes with the amino acids glycine, cysteine, histidine, and tryptophan were performed. The standard thermodynamic reaction parameters ΔH°, ΔS°, and ΔV° were determined and showed that both of the sequential axial substitution reactions are enthalpy driven. Kinetic rate laws and rate constants were determined for the axial substitution reactions of coordinated water by the amino acids that gave the corresponding aqua(amino acid)-Ru(2) substituted species. The results revealed that the [Ru(2)(CH(3)COO)(4)](+) paddlewheel framework remained stable during the axial ligand substitution reactions and was also mostly preserved in the presence of the amino acids.

  4. Caffeine sensitivity of native RyR channels from normal and malignant hyperthermic pigs: effects of a DHPR II-III loop peptide.

    PubMed

    Gallant, Esther M; Hart, James; Eager, Kevin; Curtis, Suzanne; Dulhunty, Angela F

    2004-04-01

    Enhanced sensitivity to caffeine is part of the standard tests for susceptibility to malignant hyperthermia (MH) in humans and pigs. The caffeine sensitivity of skeletal muscle contraction and Ca(2+) release from the sarcoplasmic reticulum is enhanced, but surprisingly, the caffeine sensitivity of purified porcine ryanodine receptor Ca(2+)-release channels (RyRs) is not affected by the MH mutation (Arg(615)Cys). In contrast, we show here that native malignant hyperthermic pig RyRs (incorporated into lipid bilayers with RyR-associated lipids and proteins) were activated by caffeine at 100- to 1000-fold lower concentrations than native normal pig RyRs. In addition, the results show that the mutant ryanodine receptor channels were less sensitive to high-affinity activation by a peptide (C(S)) that corresponds to a part of the II-III loop of the skeletal dihydropyridine receptor (DHPR). Furthermore, subactivating concentrations of peptide C(S) enhanced the response of normal pig and rabbit RyRs to caffeine. In contrast, the caffeine sensitivity of MH RyRs was not enhanced by the peptide. These novel results showed that in MH-susceptible pig muscles 1). the caffeine sensitivity of native RyRs was enhanced, 2). the sensitivity of RyRs to a skeletal II-III loop peptide was depressed, and 3). an interaction between the caffeine and peptide C(S) activation mechanisms seen in normal RyRs was lost.

  5. Identifying Potential Mechanisms Enabling Acidophily in the Ammonia-Oxidizing Archaeon "Candidatus Nitrosotalea devanaterra".

    PubMed

    Lehtovirta-Morley, Laura E; Sayavedra-Soto, Luis A; Gallois, Nicolas; Schouten, Stefan; Stein, Lisa Y; Prosser, James I; Nicol, Graeme W

    2016-05-01

    Ammonia oxidation is the first and rate-limiting step in nitrification and is dominated by two distinct groups of microorganisms in soil: ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). AOA are often more abundant than AOB and dominate activity in acid soils. The mechanism of ammonia oxidation under acidic conditions has been a long-standing paradox. While high rates of ammonia oxidation are frequently measured in acid soils, cultivated ammonia oxidizers grew only at near-neutral pH when grown in standard laboratory culture. Although a number of mechanisms have been demonstrated to enable neutrophilic AOB growth at low pH in the laboratory, these have not been demonstrated in soil, and the recent cultivation of the obligately acidophilic ammonia oxidizer "Candidatus Nitrosotalea devanaterra" provides a more parsimonious explanation for the observed high rates of activity. Analysis of the sequenced genome, transcriptional activity, and lipid content of "Ca Nitrosotalea devanaterra" reveals that previously proposed mechanisms used by AOB for growth at low pH are not essential for archaeal ammonia oxidation in acidic environments. Instead, the genome indicates that "Ca Nitrosotalea devanaterra" contains genes encoding both a predicted high-affinity substrate acquisition system and potential pH homeostasis mechanisms absent in neutrophilic AOA. Analysis of mRNA revealed that candidate genes encoding the proposed homeostasis mechanisms were all expressed during acidophilic growth, and lipid profiling by high-performance liquid chromatography-mass spectrometry (HPLC-MS) demonstrated that the membrane lipids of "Ca Nitrosotalea devanaterra" were not dominated by crenarchaeol, as found in neutrophilic AOA. This study for the first time describes a genome of an obligately acidophilic ammonia oxidizer and identifies potential mechanisms enabling this unique phenotype for future biochemical characterization.

  6. Identifying Potential Mechanisms Enabling Acidophily in the Ammonia-Oxidizing Archaeon “Candidatus Nitrosotalea devanaterra”

    PubMed Central

    Sayavedra-Soto, Luis A.; Gallois, Nicolas; Schouten, Stefan; Stein, Lisa Y.; Prosser, James I.; Nicol, Graeme W.

    2016-01-01

    Ammonia oxidation is the first and rate-limiting step in nitrification and is dominated by two distinct groups of microorganisms in soil: ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). AOA are often more abundant than AOB and dominate activity in acid soils. The mechanism of ammonia oxidation under acidic conditions has been a long-standing paradox. While high rates of ammonia oxidation are frequently measured in acid soils, cultivated ammonia oxidizers grew only at near-neutral pH when grown in standard laboratory culture. Although a number of mechanisms have been demonstrated to enable neutrophilic AOB growth at low pH in the laboratory, these have not been demonstrated in soil, and the recent cultivation of the obligately acidophilic ammonia oxidizer “Candidatus Nitrosotalea devanaterra” provides a more parsimonious explanation for the observed high rates of activity. Analysis of the sequenced genome, transcriptional activity, and lipid content of “Ca. Nitrosotalea devanaterra” reveals that previously proposed mechanisms used by AOB for growth at low pH are not essential for archaeal ammonia oxidation in acidic environments. Instead, the genome indicates that “Ca. Nitrosotalea devanaterra” contains genes encoding both a predicted high-affinity substrate acquisition system and potential pH homeostasis mechanisms absent in neutrophilic AOA. Analysis of mRNA revealed that candidate genes encoding the proposed homeostasis mechanisms were all expressed during acidophilic growth, and lipid profiling by high-performance liquid chromatography–mass spectrometry (HPLC-MS) demonstrated that the membrane lipids of “Ca. Nitrosotalea devanaterra” were not dominated by crenarchaeol, as found in neutrophilic AOA. This study for the first time describes a genome of an obligately acidophilic ammonia oxidizer and identifies potential mechanisms enabling this unique phenotype for future biochemical characterization. PMID:26896134

  7. Direct Determination of Equilibrium Potentials for Hydrogen Oxidation/Production by Open Circuit Potential Measurements in Acetonitrile

    SciTech Connect

    Roberts, John A. S.; Bullock, R. Morris

    2013-04-01

    Open circuit potentials were measured for acetonitrile solutions of a variety of acids and their conjugate bases under 1 atm H2. Acids examined were triethylammonium, dimethylformamidium, 2,6-dichloroanilinium, 4-cyanoanilinium, 4-bromoanilinium, and 4-anisidinium salts. These potentials, along with the pKa values of the acids, establish the value of the standard hydrogen electrode (SHE) potential in acetonitrile as -0.028(4) V vs the ferrocenium/ferrocene couple. Dimethylformamidium forms homoconjugates and other aggregates with dimethylformamide; open circuit potentials (OCPs) were used to quantify the extent of these reactions. Overpotentials for electrocatalytic hydrogen production and oxidation were determined from open circuit potentials and voltammograms of acidic or basic catalyst solutions under H2. For these solutions, agreement between OCP values and potentials calculated using the Nernst equation is within 12 mV. Finally, use of the measured equilibrium potential allows direct comparison of catalytic systems in different media; it requires neither pKa values, homoconjugation constants, nor the SHE potential.

  8. Direct determination of equilibrium potentials for hydrogen oxidation/production by open circuit potential measurements in acetonitrile.

    PubMed

    Roberts, John A S; Bullock, R Morris

    2013-04-01

    Open circuit potentials were measured for acetonitrile solutions of a variety of acids and their conjugate bases under 1 atm H2. Acids examined were triethylammonium, dimethylformamidium, 2,6-dichloroanilinium, 4-cyanoanilinium, 4-bromoanilinium, and 4-anisidinium salts. These potentials, along with the pKa values of the acids, establish the value of the standard hydrogen electrode (SHE) potential in acetonitrile as -0.028(4) V vs the ferrocenium/ferrocene couple. Dimethylformamidium forms homoconjugates and other aggregates with dimethylformamide; open circuit potentials (OCPs) were used to quantify the extent of these reactions. Overpotentials for electrocatalytic hydrogen production and oxidation were determined from open circuit potentials and voltammograms of acidic or basic catalyst solutions under H2. For these solutions, agreement between OCP values and potentials calculated using the Nernst equation is within 12 mV. Use of the measured equilibrium potential allows direct comparison of catalytic systems in different media; it requires neither pKa values, homoconjugation constants, nor the SHE potential.

  9. Theoretical study of ionization and one-electron oxidation potentials of N-heterocyclic compounds.

    PubMed

    Sviatenko, Liudmyla K; Gorb, Leonid; Hill, Frances C; Leszczynski, Jerzy

    2013-05-15

    A number of density functionals was utilized to predict gas-phase adiabatic ionization potentials (IPs) for nitrogen-rich heterocyclic compounds. Various solvation models were applied to the calculation of difference in free energies of solvation of oxidized and reduced forms of heterocyclic compounds in acetonitrile (AN) for correct reproduction of their standard oxidation potentials. We developed generally applicable protocols that could successfully predict the gas-phase adiabatic ionization potentials of nitrogen-rich heterocyclic compounds and their standard oxidation potentials in AN. This approach is supported by a MPW1K/6-31+G(d) level of theory which uses SMD(UA0) approximation for estimation of solvation energy of neutral molecules and PCM(UA0) model for ionized ones. The mean absolute derivation (MAD) and root mean square error (RMSE) of the current theoretical models for IP are equal to 0.22 V and 0.26, respectively, and for oxidation potentials MAD = 0.13 V and RMSE = 0.17.

  10. Accelerated Aging in Schizophrenia Patients: The Potential Role of Oxidative Stress

    PubMed Central

    Okusaga, Olaoluwa O

    2014-01-01

    Several lines of evidence suggest that schizophrenia, a severe mental illness characterized by delusions, hallucinations and thought disorder is associated with accelerated aging. The free radical (oxidative stress) theory of aging assumes that aging occurs as a result of damage to cell constituents and connective tissues by free radicals arising from oxygen-associated reactions. Schizophrenia has been associated with oxidative stress and chronic inflammation, both of which also appear to reciprocally induce each other in a positive feedback manner. The buildup of damaged macromolecules due to increased oxidative stress and failure of protein repair and maintenance systems is an indicator of aging both at the cellular and organismal level. When compared with age-matched healthy controls, schizophrenia patients have higher levels of markers of oxidative cellular damage such as protein carbonyls, products of lipid peroxidation and DNA hydroxylation. Potential confounders such as antipsychotic medication, smoking, socio-economic status and unhealthy lifestyle make it impossible to solely attribute the earlier onset of aging-related changes or oxidative stress to having a diagnosis of schizophrenia. Regardless of whether oxidative stress can be attributed solely to a diagnosis of schizophrenia or whether it is due to other factors associated with schizophrenia, the available evidence is in support of increased oxidative stress-induced cellular damage of macromolecules which may play a role in the phenomenon of accelerated aging presumed to be associated with schizophrenia. PMID:25110609

  11. Accelerated aging in schizophrenia patients: the potential role of oxidative stress.

    PubMed

    Okusaga, Olaoluwa O

    2014-08-01

    Several lines of evidence suggest that schizophrenia, a severe mental illness characterized by delusions, hallucinations and thought disorder is associated with accelerated aging. The free radical (oxidative stress) theory of aging assumes that aging occurs as a result of damage to cell constituents and connective tissues by free radicals arising from oxygen-associated reactions. Schizophrenia has been associated with oxidative stress and chronic inflammation, both of which also appear to reciprocally induce each other in a positive feedback manner. The buildup of damaged macromolecules due to increased oxidative stress and failure of protein repair and maintenance systems is an indicator of aging both at the cellular and organismal level. When compared with age-matched healthy controls, schizophrenia patients have higher levels of markers of oxidative cellular damage such as protein carbonyls, products of lipid peroxidation and DNA hydroxylation. Potential confounders such as antipsychotic medication, smoking, socio-economic status and unhealthy lifestyle make it impossible to solely attribute the earlier onset of aging-related changes or oxidative stress to having a diagnosis of schizophrenia. Regardless of whether oxidative stress can be attributed solely to a diagnosis of schizophrenia or whether it is due to other factors associated with schizophrenia, the available evidence is in support of increased oxidative stress-induced cellular damage of macromolecules which may play a role in the phenomenon of accelerated aging presumed to be associated with schizophrenia.

  12. Investigation into the oxidative potential generated by the formation of particulate matter from incense combustion.

    PubMed

    Chuang, Hsiao-Chi; BéruBé, Kelly; Lung, Shih-Chun C; Bai, Kuan-Jen; Jones, Tim

    2013-01-15

    The formation of aerosols during combustion plays an important role in allowing released products to interreact, leading to an increase in particulate matter oxidative potential. This study investigated the physicochemistry of incense combustion-derived pollutants, which were emitted into the ambient air as solid and gas phases, followed by the determination of their oxidative potential. Upon combustion of a joss stick, approximately 60% of the mass of incense raw ingredients was released into the ambient air as combustion products including 349.51 mg/g PM(10), 145.48 mg/g CO and 0.16 mg/g NOx. Furthermore, incense combustion produced significant number of primary particles (<50 nm) at 0.99×10(5) 1/h. The NOx generated during incense combustion was able to react with CaCO(3) to produce the final product of Ca(NO(3))(2) in the ambient air. Moreover, coagulation could be a vital process for the growth of primary incense combustion particles through the intermixing with volatile organics. The incense particle's reactions with other combustion-derived products could be responsible for their significant oxidative capacity of 33.1-43.4% oxidative DNA damage. This study demonstrated that the oxidative potential of incense particles appeared to be related to the process of particle formation, and also provided novel data for the respiratory exposure assessment.

  13. Benthic ammonia oxidizers differ in community structure and biogeochemical potential across a riverine delta

    PubMed Central

    Damashek, Julian; Smith, Jason M.; Mosier, Annika C.; Francis, Christopher A.

    2015-01-01

    Nitrogen pollution in coastal zones is a widespread issue, particularly in ecosystems with urban or agricultural watersheds. California's Sacramento-San Joaquin Delta, at the landward reaches of San Francisco Bay, is highly impacted by both agricultural runoff and sewage effluent, leading to chronically high nutrient loadings. In particular, the extensive discharge of ammonium into the Sacramento River has altered this ecosystem by vastly increasing ammonium concentrations and thus changing the stoichiometry of inorganic nitrogen stocks, with potential effects throughout the food web. This debate surrounding ammonium inputs highlights the importance of understanding the rates of, and controls on, nitrogen (N) cycling processes across the delta. To date, however, there has been little research examining N biogeochemistry or N-cycling microbial communities in this system. We report the first data on benthic ammonia-oxidizing microbial communities and potential nitrification rates for the Sacramento-San Joaquin Delta, focusing on the functional gene amoA (which codes for the α-subunit of ammonia monooxygenase). There were stark regional differences in ammonia-oxidizing communities, with ammonia-oxidizing bacteria (AOB) outnumbering ammonia-oxidizing archaea (AOA) only in the ammonium-rich Sacramento River. High potential nitrification rates in the Sacramento River suggested these communities may be capable of oxidizing significant amounts of ammonium, compared to the San Joaquin River and the upper reaches of San Francisco Bay. Gene diversity also showed regional patterns, as well as phylogenetically unique ammonia oxidizers in the Sacramento River. The benthic ammonia oxidizers in this nutrient-rich aquatic ecosystem may be important players in its overall nutrient cycling, and their community structure and biogeochemical function appear related to nutrient loadings. Unraveling the microbial ecology and biogeochemistry of N cycling pathways, including benthic

  14. Tetra-μ-acetato-κ8 O:O′-bis­[(3-cyano­pyridine-κN 1)ruthenium(II,III)](Ru—Ru) hexa­fluoridophosphate 1,2-dichloro­ethane monosolvate

    PubMed Central

    Minaker, Samuel A.; Wang, Ruiyao; Aquino, Manuel A. S.

    2011-01-01

    The title compound, [Ru2(CH3CO2)4(C6H4N2)2]PF6·C2H4Cl2, was obtained via a rapid substitution reaction in 2-propanol whereby 3-cyano­pyridine replaces the axial water mol­ecules in the diaquatetra-μ-acetato-diruthenium(II,III) hexa­fluorido­phosphate starting material. The product rapidly precipated and crystals were grown from 1,2-dichloro­ethane. The 1,2-dichloro­ethane mol­ecule of solvation exhibits disorder with two different orientations [occupancy ratio 0.51 (6):0.49 (6)]. All three parts, the cation, the anion and the disordered solvent mol­ecule lie on crystallographic inversion centers. The Ru—Ru bond length of 2.2702 (6) Å fits nicely into the range seen for similar complexes and correlates well with the reduction potential of the complex and donor strength of the axial ligand, 3-cyano­pyridine, as postulated in a previous study [Vamvounis et al. (2000 ▶). Inorg. Chim. Acta, 305, 87–98]. The 3-cyano­pyridine ligands orient themselves in an anti configuration with respect to each other and the Ru—Ru—N angle [174.27 (7)°] is close to being linear. PMID:22219795

  15. A many-body potential approach to modelling the thermomechanical properties of actinide oxides.

    PubMed

    Cooper, M W D; Rushton, M J D; Grimes, R W

    2014-03-12

    A many-body potential model for the description of actinide oxide systems, which is robust at high temperatures, is reported for the first time. The embedded atom method is used to describe many-body interactions ensuring good reproduction of a range of thermophysical properties (lattice parameter, bulk modulus, enthalpy and specific heat) between 300 and 3000 K for AmO2, CeO2, CmO2, NpO2, ThO2, PuO2 and UO2. Additionally, the model predicts a melting point for UO2 between 3000 and 3100 K, in close agreement with experiment. Oxygen-oxygen interactions are fixed across the actinide oxide series because it facilitates the modelling of oxide solid solutions. The new potential is also used to predict the energies of Schottky and Frenkel pair disorder processes.

  16. The unaccounted yet abundant nitrous oxide-reducing microbial community: a potential nitrous oxide sink

    PubMed Central

    Jones, Christopher M; Graf, Daniel RH; Bru, David; Philippot, Laurent; Hallin, Sara

    2013-01-01

    Nitrous oxide (N2O) is a major radiative forcing and stratospheric ozone-depleting gas emitted from terrestrial and aquatic ecosystems. It can be transformed to nitrogen gas (N2) by bacteria and archaea harboring the N2O reductase (N2OR), which is the only known N2O sink in the biosphere. Despite its crucial role in mitigating N2O emissions, knowledge of the N2OR in the environment remains limited. Here, we report a comprehensive phylogenetic analysis of the nosZ gene coding the N2OR in genomes retrieved from public databases. The resulting phylogeny revealed two distinct clades of nosZ, with one unaccounted for in studies investigating N2O-reducing communities. Examination of N2OR structural elements not considered in the phylogeny revealed that the two clades differ in their signal peptides, indicating differences in the translocation pathway of the N2OR across the membrane. Sequencing of environmental clones of the previously undetected nosZ lineage in various environments showed that it is widespread and diverse. Using quantitative PCR, we demonstrate that this clade was most often at least as abundant as the other, thereby more than doubling the known extent of the overall N2O-reducing community in the environment. Furthermore, we observed that the relative abundance of nosZ from either clade varied among habitat types and environmental conditions. Our results indicate a physiological dichotomy in the diversity of N2O-reducing microorganisms, which might be of importance for understanding the relationship between the diversity of N2O-reducing microorganisms and N2O reduction in different ecosystems. PMID:23151640

  17. ANAEROBIC DDT BIOTRANSFORMATION: ENHANCEMENT BY APPLICATION OF SURFACTANTS AND LOW OXIDATION REDUCTION POTENTIAL

    EPA Science Inventory

    Enhancement of anaerobic DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane) biotransformation by mixed cultures was studied with application of surfactants and oxidation reduction potential reducing agents. Without amendments, DDT transformation resulted mainly in the pr...

  18. Oxidized Volcanic Materials as a Potential Explanation for Gray Hematite Regions on Mars

    NASA Technical Reports Server (NTRS)

    Minitti, M. E.; Lane, M. D.; Bishop, J. L.

    2002-01-01

    Martian-analogue basalts synthesized, then oxidized, in the laboratory exhibit gray hematite coatings on exposed glass surfaces. We explore potential connections between these hematite coatings and the coarse, gray hematite signatures seen on Mars. Additional information is contained in the original extended abstract.

  19. COMPUTATIONAL ELECTROCHEMISTRY: AQUEOUS ONE-ELECTRON OXIDATION POTENTIALS FOR SUBSTITUTED ANILINES

    EPA Science Inventory

    Semiempirical molecular orbital theory and density functional theory are used to compute one-electron oxidation potentials for aniline and a set of 21 mono- and di-substituted anilines in aqueous solution. Linear relationships between theoretical predictions and experiment are co...

  20. COMPUTATIONAL ELECTROCHEMISTRY: AQUEOUS ONE-ELECTRON OXIDATION POTENTIALS FOR SUBSTITUTED ANILINES

    EPA Science Inventory

    Semiempirical molecular orbital theory and density functional theory are used to compute one-electron oxidation potentials for aniline and a set of 21 mono- and di-substituted anilines in aqueous solution. Linear relationships between theoretical predictions and experiment are co...

  1. Influence of oxygenated organic aerosols (OOAs) on the oxidative potential of diesel and biodiesel particulate matter.

    PubMed

    Stevanovic, S; Miljevic, B; Surawski, N C; Fairfull-Smith, K E; Bottle, S E; Brown, R; Ristovski, Z D

    2013-07-16

    Generally, the magnitude of pollutant emissions from diesel engines running on biodiesel fuel is ultimately coupled to the structure of the fuel's constituent molecules. Previous studies demonstrated the relationship between the organic fraction of particulate matter (PM) and its oxidative potential. Herein, emissions from a diesel engine running on different biofuels were analyzed in more detail to explore the role that different organic fractions play in the measured oxidative potential. In this work, a more detailed chemical analysis of biofuel PM was undertaken using a compact time of flight aerosol mass spectrometer (c-ToF AMS). This enabled a better identification of the different organic fractions that contribute to the overall measured oxidative potentials. The concentration of reactive oxygen species (ROS) was measured using a profluorescent nitroxide molecular probe 9-(1,1,3,3-tetramethylisoindolin-2-yloxyl-5-ethynyl)-10-(phenylethynyl)anthracene (BPEAnit). Therefore, the oxidative potential of the PM, measured through the ROS content, although proportional to the total organic content in certain cases, shows a much higher correlation with the oxygenated organic fraction as measured by the c-ToF AMS. This highlights the importance of knowing the surface chemistry of particles for assessing their health impacts. It also sheds light onto new aspects of particulate emissions that should be taken into account when establishing relevant metrics for assessing health implications of replacing diesel with alternative fuels.

  2. ANAEROBIC DDT BIOTRANSFORMATION: ENHANCEMENT BY APPLICATION OF SURFACTANTS AND LOW OXIDATION REDUCTION POTENTIAL

    EPA Science Inventory

    Enhancement of anaerobic DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane) biotransformation by mixed cultures was studied with application of surfactants and oxidation reduction potential reducing agents. Without amendments, DDT transformation resulted mainly in the pr...

  3. Insertion of alpha1S II-III loop and C terminal sequences into alpha1H fails to restore excitation-contraction coupling in dysgenic myotubes.

    PubMed

    Wilkens, Christina M; Beam, Kurt G

    2003-01-01

    The L-type Ca2+ channel in skeletal muscle (alpha1S) is essential for excitation-contraction (EC) coupling. Previous studies using chimeras composed of alpha1S together with alpha1C or alpha1M demonstrated the importance of the alpha1S II-III loop and of a smaller subdomain (residues 720-764; 'ECC') in skeletal EC coupling. However, these chimeras failed to test the significance of regions outside the II-III loop, which are highly conserved between alpha1S and alpha1C. Therefore, we have injected dysgenic (alpha1S-lacking) myotubes with cDNAs encoding chimeras between alpha1S and the highly divergent T-type Ca2+ channel, alpha1H. The chimeras consisted of GFP-tagged alpha1H with one or more of the following substitutions: alpha1S II-III loop residues 720-764 ('ECC'), a putative targeting domain of the alpha1S C terminus ('target'; residues 1543-1662) or the entire alpha1S C terminus ('Cterm'; residues 1382-1873). The presence of either target or Cterm affected the expression and/or kinetics of whole-cell currents recorded from both dysgenic muscle cells and tsa-201 cells. Importantly, substitution of ECC alone into GFP-alpha1H (GFP-alpha1H + ECC), or together with either target (GFP-alpha1H + ECC + target) or Cterm (GFP-alpha1H + ECC + Cterm), was insufficient to restore electrically evoked contractions. Depolarization-induced fluorescence transients for GFP-alpha1H + ECC, GFP-alpha1H + ECC + target or GFP-alpha1H + ECC + Cterm had a bell shaped dependence upon membrane voltage (inconsistent with skeletal EC coupling) and were also exceedingly small (unlike cardiac EC coupling). The absence of EC coupling for these chimeras raises the possibility that regions of alpha1S outside of ECC and target are necessary for providing the context that allows these two domains to function in EC coupling and targeting, respectively. Additionally, an inadequate membrane density of the chimeras may have contributed to the lack of coupling.

  4. IDH mutation status and role of WHO grade and mitotic index in overall survival in grade II-III diffuse gliomas.

    PubMed

    Olar, Adriana; Wani, Khalida M; Alfaro-Munoz, Kristin D; Heathcock, Lindsey E; van Thuijl, Hinke F; Gilbert, Mark R; Armstrong, Terri S; Sulman, Erik P; Cahill, Daniel P; Vera-Bolanos, Elizabeth; Yuan, Ying; Reijneveld, Jaap C; Ylstra, Bauke; Wesseling, Pieter; Aldape, Kenneth D

    2015-04-01

    Diffuse gliomas are up till now graded based upon morphology. Recent findings indicate that isocitrate dehydrogenase (IDH) mutation status defines biologically distinct groups of tumors. The role of tumor grade and mitotic index in patient outcome has not been evaluated following stratification by IDH mutation status. To address this, we interrogated 558 WHO grade II-III diffuse gliomas for IDH1/2 mutations and investigated the prognostic impact of WHO grade within IDH-mutant and IDH-wild type tumor subsets independently. The prognostic impact of grade was modest in IDH-mutant [hazard ratio (HR) = 1.21, 95 % confidence interval (CI) = 0.91-1.61] compared to IDH-wild type tumors (HR = 1.74, 95 % CI = 0.95-3.16). Using a dichotomized mitotic index cut-off of 4/1000 tumor cells, we found that while mitotic index was significantly associated with outcome in IDH-wild type tumors (log-rank p < 0.0001, HR = 4.41, 95 % CI = 2.55-7.63), it was not associated with outcome in IDH-mutant tumors (log-rank p = 0.5157, HR = 1.10, 95 % CI = 0.80-1.51), and could demonstrate a statistical interaction (p < 0.0001) between IDH mutation and mitotic index (i.e., suggesting that the effect of mitotic index on patient outcome is dependent on IDH mutation status). Patient age, an established prognostic factor in diffuse glioma, was significantly associated with outcome only in the IDH-wild type subset, and consistent with prior data, 1p/19q co-deletion conferred improved outcome in the IDH-mutant cohort. These findings suggest that stratification of grade II-III gliomas into subsets defined by the presence or absence of IDH mutation leads to subgroups with distinct prognostic characteristics. Further evaluation of grading criteria and prognostic markers is warranted within IDH-mutant versus IDH-wild type diffuse grade II-III gliomas as independent entities.

  5. Protein Kinase A Governs Oxidative Phosphorylation Kinetics and Oxidant Emitting Potential at Complex I

    PubMed Central

    Lark, Daniel S.; Reese, Lauren R.; Ryan, Terence E.; Torres, Maria J.; Smith, Cody D.; Lin, Chien-Te; Neufer, P. Darrell

    2015-01-01

    The mitochondrial electron transport system (ETS) is responsible for setting and maintaining both the energy and redox charges throughout the cell. Reversible phosphorylation of mitochondrial proteins, particularly via the soluble adenylyl cyclase (sAC)/cyclic AMP (cAMP)/Protein kinase A (PKA) axis, has recently been revealed as a potential mechanism regulating the ETS. However, the governance of cAMP/PKA signaling and its implications on ETS function are incompletely understood. In contrast to prior reports using exogenous bicarbonate, we provide evidence that endogenous CO2 produced by increased tricarboxylic acid (TCA) cycle flux is insufficient to increase mitochondrial cAMP levels, and that exogenous addition of membrane permeant 8Br-cAMP does not enhance mitochondrial respiratory capacity. We also report important non-specific effects of commonly used inhibitors of sAC which preclude their use in studies of mitochondrial function. In isolated liver mitochondria, inhibition of PKA reduced complex I-, but not complex II-supported respiratory capacity. In permeabilized myofibers, inhibition of PKA lowered both the Km and Vmax for complex I-supported respiration as well as succinate-supported H2O2 emitting potential. In summary, the data provided here improve our understanding of how mitochondrial cAMP production is regulated, illustrate a need for better tools to examine the impact of sAC activity on mitochondrial biology, and suggest that cAMP/PKA signaling contributes to the governance of electron flow through complex I of the ETS. PMID:26635618

  6. Protein Kinase A Governs Oxidative Phosphorylation Kinetics and Oxidant Emitting Potential at Complex I.

    PubMed

    Lark, Daniel S; Reese, Lauren R; Ryan, Terence E; Torres, Maria J; Smith, Cody D; Lin, Chien-Te; Neufer, P Darrell

    2015-01-01

    The mitochondrial electron transport system (ETS) is responsible for setting and maintaining both the energy and redox charges throughout the cell. Reversible phosphorylation of mitochondrial proteins, particularly via the soluble adenylyl cyclase (sAC)/cyclic AMP (cAMP)/Protein kinase A (PKA) axis, has recently been revealed as a potential mechanism regulating the ETS. However, the governance of cAMP/PKA signaling and its implications on ETS function are incompletely understood. In contrast to prior reports using exogenous bicarbonate, we provide evidence that endogenous CO2 produced by increased tricarboxylic acid (TCA) cycle flux is insufficient to increase mitochondrial cAMP levels, and that exogenous addition of membrane permeant 8Br-cAMP does not enhance mitochondrial respiratory capacity. We also report important non-specific effects of commonly used inhibitors of sAC which preclude their use in studies of mitochondrial function. In isolated liver mitochondria, inhibition of PKA reduced complex I-, but not complex II-supported respiratory capacity. In permeabilized myofibers, inhibition of PKA lowered both the K m and V max for complex I-supported respiration as well as succinate-supported H2O2 emitting potential. In summary, the data provided here improve our understanding of how mitochondrial cAMP production is regulated, illustrate a need for better tools to examine the impact of sAC activity on mitochondrial biology, and suggest that cAMP/PKA signaling contributes to the governance of electron flow through complex I of the ETS.

  7. Oxidation potentials of functionalized sulfone solvents for high-voltage Li-ion batteries: a computational study.

    PubMed

    Shao, Nan; Sun, Xiao-Guang; Dai, Sheng; Jiang, De-en

    2012-03-15

    New electrolytes with large electrochemical windows are needed to meet the challenge for high-voltage Li-ion batteries. Sulfone as an electrolyte solvent boasts of high oxidation potentials. Here we examine the effect of multiple functionalization on sulfone's oxidation potential. We compute oxidation potentials for a series of sulfone-based molecules functionalized with fluorine, cyano, ester, and carbonate groups by using a quantum chemistry method within a continuum solvation model. We find that multifunctionalization is a key to achieving high oxidation potentials. This can be realized through either a fluorether group on a sulfone molecule or sulfonyl fluoride with a cyano or ester group. © 2012 American Chemical Society

  8. Oxidation Potentials of Functionalized Sulfone Solvents for High-Voltage Li-Ion Batteries: A Computational Study

    SciTech Connect

    Shao, Nan; Sun, Xiao-Guang; Dai, Sheng; Jiang, Deen

    2012-01-01

    New electrolytes with large electrochemical windows are needed to meet the challenge for high-voltage Li-ion batteries. Sulfone as an electrolyte solvent boasts of high oxidation potentials. Here we examine the effect of multiple functionalization on sulfone's oxidation potential. We compute oxidation potentials for a series of sulfone-based molecules functionalized with fluorine, cyano, ester, and carbonate groups by using a quantum chemistry method within a continuum solvation model. We find that multifunctionalization is a key to achieving high oxidation potentials. This can be realized through either a fluorether group on a sulfone molecule or sulfonyl fluoride with a cyano or ester group.

  9. Fibrotic Effects of Arecoline N-Oxide in Oral Potentially Malignant Disorders.

    PubMed

    Kuo, Tzer-Min; Luo, Shun-Yuan; Chiang, Shang-Lun; Yeh, Kun-Tu; Hsu, Hui-Ting; Wu, Cheng-Tien; Lu, Chi-Yu; Tsai, Ming-Hsui; Chang, Jan-Gowth; Ko, Ying-Chin

    2015-06-24

    The metabolites of environmental chemicals play key roles in carcinogenesis. Areca nut is strongly associated with the development of oral potentially malignant disorders (OPMD) or cancer. The main alkaloid in the areca nut is arecoline, which is highly cytotoxic and genotoxic. Arecoline N-oxide, a metabolite of areca nut alkaloids, which has been identified in animal urine, has been shown to induce mutagenicity in bacteria. In this study, it was found that its protein adduct could be detected in oral keratinocytes treated with areca nut extract. Increased collagen expression and severity of squamous hyperplasia were observed in arecoline N-oxide treated mice. In cultured oral fibroblasts, arecoline N-oxide showed stronger effects on the increase of fibrotic related genes including TGF-beta1, S100A4, MMP-9, IL-6, and fibronectin and a decrease of E-cadherin as compared with arecoline. Finally, arecoline N-oxide stimulation effectively increased the DNA damage marker, gamma-H2A.X, both in vitro and in vivo. Taken together, these results indicate that arecoline N-oxide shows a high potential for the induction of OPMD.

  10. Fluctuation Analysis of Redox Potential to Distinguish Microbial Fe(II) Oxidation.

    PubMed

    Enright, A M L; Ferris, F G

    2016-11-01

    We developed a novel method for distinguishing abiotic and biological iron oxidation in liquid media using oxidation-reduction (redox) potential time series data. The instrument and processing algorithm were tested by immersing the tip of a Pt electrode with an Ag-AgCl reference electrode into an active iron-oxidizing biofilm in a groundwater discharge zone, as well as in two abiotic systems: a killed sample and a chemical control from the same site. We used detrended fluctuation analysis to characterize average root mean square fluctuation behavior, which was distinct in the live system. The calculated α value scaling exponents determined by detrended fluctuation analysis were significantly different at p < 0.001. This indicates that time series of electrode response data may be used to distinguish live and abiotic chemical reaction pathways. Due to the simplicity, portability, and small size, it may be suitable for characterization of extraterrestrial environments where water has been observed, such as Mars and Europa. Key Words: Oxidation-reduction potential-Detrended fluctuation analysis-Iron-oxidizing bacteria. Astrobiology 16, 846-852.

  11. The potential of Angeli’s salt to decrease nitric oxide scavenging by plasma hemoglobin

    PubMed Central

    He, Xiaojun; Azarov, Ivan; Jeffers, Anne; Presley, Tennille; Richardson, Jodi; King, S. Bruce; Gladwin, Mark T.; Kim-Shapiro, Daniel B.

    2008-01-01

    Release of hemoglobin from the erythrocyte during intravascular hemolysis contributes to the pathology of a variety of diseased states. This effect is partially due to the enhanced ability of cell-free plasma hemoglobin, which is primarily found in the ferrous, oxygenated state, to scavenge nitric oxide. Oxidation of the cell-free hemoglobin to methemoglobin, which does not effectively scavenge nitric oxide, using inhaled nitric oxide has been shown to be effective in limiting pulmonary and systemic vasoconstriction. However, the ferric heme species may be reduced back to ferrous hemoglobin in plasma and has the potential to drive injurious redox chemistry. We propose that compounds that selectively convert cell-free hemoglobin to ferric, and ideally iron-nitrosylated heme species that do not actively scavenge nitric oxide would effectively treat intravascular hemolysis. We show here that nitroxyl, generated by Angeli’s salt (Sodium α-oxyhyponitrite, Na2N2O3), preferentially reacts with cell-free hemoglobin compared to that encapsulated in the red blood cell under physiologically relevant conditions. Nitroxyl oxidizes oxygenated ferrous hemoglobin to methemoglobin and can convert the methemoglobin to a more stable, less toxic species, iron-nitrosyl hemoglobin. These results support the notion that Angeli’s salt or a similar compound could be used to effectively treat conditions associated with intravascular hemolysis. PMID:18243145

  12. Evolutionary Optimization of a Charge Transfer Ionic Potential Model for Ta/Ta-Oxide Heterointerfaces

    DOE PAGES

    Sasikumar, Kiran; Narayanan, Badri; Cherukara, Mathew; ...

    2017-03-19

    Heterostructures of tantalum and its oxide are of tremendous technological interest for a myriad of technological applications, including electronics, thermal management, catalysis and biochemistry. In particular, local oxygen stoichiometry variation in TaOx memristors comprising of thermodynamically stable metallic (Ta) and insulating oxide (Ta2O5) have been shown to result in fast switching on the subnanosecond timescale over a billion cycles. This rapid switching opens up the potential for advanced functional platforms such as stateful logic operations and neuromorphic computation. Despite its broad importance, an atomistic scale understanding of oxygen stoichiometry variation across Ta/TaOx heterointerfaces, such as during early stages of oxidationmore » and oxide growth, is not well understood. This is mainly due to the lack of a unified interatomic potential model for tantalum oxides that can accurately describe metallic (Ta), ionic (TaOx) as well as mixed (Ta/TaOx interfaces) bonding environments simultaneously. To address this challenge, we introduce a Charge Transfer Ionic Potential (CTIP) model for Ta/Ta-oxide system by training against lattice parameters, cohesive energies, equations of state (EOS), elastic properties, and surface energies of the various experimentally observed Ta2O5 polymorphs (hexagonal, orthorhombic and monoclinic) obtained from density functional theory (DFT) calculations. The best CTIP parameters are determined by employing a global optimization scheme driven by genetic algorithms followed by local Simplex optimization. Our newly developed CTIP potential accurately predicts structure, thermodynamics, energetic ordering of polymorphs, as well as elastic and surface properties of both Ta and Ta2O5, in excellent agreement with DFT calculations and experiments. We employ our newly parameterized CTIP potential to investigate the early stages of oxidation and atomic scale mechanisms associated with oxide growth on Ta surface at various

  13. Exogenous amino acids suppress glucose oxidation and potentiate hepatic glucose production in late gestation fetal sheep.

    PubMed

    Brown, Laura D; Kohn, Jaden R; Rozance, Paul J; Hay, William W; Wesolowski, Stephanie R

    2017-05-01

    Acute amino acid (AA) infusion increases AA oxidation rates in normal late gestation fetal sheep. Because the fetal oxygen consumption rate does not change with increased AA oxidation, we hypothesized that AA infusion would suppress glucose oxidation pathways and that the additional carbon supply from AA would activate hepatic glucose production. To test this, late gestation fetal sheep were infused intravenously for 3 h with saline or exogenous AA (AA). Glucose tracer metabolic studies were performed and skeletal muscle and liver tissues samples were collected. AA infusion increased fetal arterial plasma branched chain AA, cortisol, and glucagon concentrations. Fetal glucose utilization rates were similar between basal and AA periods, yet the fraction of glucose oxidized and the glucose oxidation rate were decreased by 40% in the AA period. AA infusion increased expression of PDK4, an inhibitor of glucose oxidation, nearly twofold in muscle and liver. In liver, AA infusion tended to increase PCK1 gluconeogenic gene and PCK1 correlated with plasma cortisol concentrations. AA infusion also increased liver mRNA expression of the lactate transporter gene (MCT1), protein expression of GLUT2 and LDHA, and phosphorylation of AMPK, 4EBP1, and S6 proteins. In isolated fetal hepatocytes, AA supplementation increased glucose production and PCK1, LDHA, and MCT1 gene expression. These results demonstrate that AA infusion into fetal sheep competitively suppresses glucose oxidation and potentiates hepatic glucose production. These metabolic patterns support flexibility in fetal metabolism in response to increased nutrient substrate supply while maintaining a relatively stable rate of oxidative metabolism. Copyright © 2017 the American Physiological Society.

  14. Plutonium Oxide Containment and the Potential for Water-Borne Transport as a Consequence of ARIES Oxide Processing Operations

    SciTech Connect

    Wayne, David Matthew; Rowland, Joel C.

    2015-02-01

    The question of oxide containment during processing and storage has become a primary concern when considering the continued operability of the Plutonium Facility (PF-4) at Los Alamos National Laboratory (LANL). An Evaluation of the Safety of the Situation (ESS), “Potential for Criticality in a Glovebox Due to a Fire” (TA55-ESS-14-002-R2, since revised to R3) first issued in May, 2014 summarizes these concerns: “The safety issue of fire water potentially entering a glovebox is: the potential for the water to accumulate in the bottom of a glovebox and result in an inadvertent criticality due to the presence of fissionable materials in the glovebox locations and the increased reflection and moderation of neutrons from the fire water accumulation.” As a result, the existing documented safety analysis (DSA) was judged inadequate and, while it explicitly considered the potential for criticality resulting from water intrusion into gloveboxes, criticality safety evaluation documents (CSEDs) for the affected locations did not evaluate the potential for fire water intrusion into a glovebox.

  15. Purification of polyclonal antibodies from Cohn fraction II + III, skim milk, and whey by affinity chromatography using a hexamer peptide ligand.

    PubMed

    Menegatti, Stefano; Naik, Amith D; Gurgel, Patrick V; Carbonell, Ruben G

    2012-11-01

    HWRGWV, a peptide that binds specifically to the Fc fragment of human immunoglobulin G (IgG), was used for the purification of IgG from Cohn fraction II + III of human plasma and from bovine skim milk and whey. The concentration of sodium chloride and sodium caprylate in the binding buffer as well as the pH of the elution buffer were optimized to achieve high IgG yield and purity. Under optimized conditions, IgG was recovered from plasma fractions with yield and purity up to 84% and 95%, respectively. IgG was also purified from skim milk with 74% yield and 92% purity and from whey with 85% yield and 93% purity. Purification experiments were also performed with Protein A resin and the results were found to be similar to those obtained with the peptide adsorbent.

  16. The azide-bridged mixed-valent cobalt(II,III) compound [(CH(3))(3)NH](2)[CoCo(2)(N(3))(10)].

    PubMed

    Liu, Yan-Ju; Li, Yu-Xian; Xu, Min; Wang, Xia

    2010-12-04

    The crystal structure of the title compound, poly[bis-(tri-methyl-ammonium) hexa-μ(1,1)-azido-tetra-azido-tricobalt-ate(II,III)], [(CH(3))(3)NH](2)[Co(II)Co(III) (2)(N(3))(10)], consists of anionic chains [Co(II)Co(III) (2)(N(3))(10)](2-) extending parallel to the c axis and [(CH(3))(3)NH](+) counter-cations situated between the chains. In the anionic chain, one tetra-hedrally coordinated Co(II) atom (site symmetry 2) and two octa-hedrally coordinated Co(III) atoms are arranged alternately and are linked by μ(1,1)-azide bridges. The anionic chains and cations are connected via N-H⋯N hydrogen bonding into a three-dimensional structure.

  17. Effect of Potential on Characteristics of Oxide Product Layers on Chalcopyrite

    NASA Astrophysics Data System (ADS)

    Juan, Yu; Hong-ying, Yang

    Electrochemical behavior of natural chalcopyrite in electrolyte solution at pH value of 6.97 was studied by cyclic voltammetry, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. The results showed that the electrochemical processes occurred on electrode surface were controlled mainly by the growth of sulfur species at lower applied potentials (<0.35Vvs.SHE), and the oxidative dissolution of sulfur species and the hydroxylation of iron at higher applied potential (>0.45V). The EIS spectra of oxide product layers could be illustrated by the equivalent circuit of Re(QdlRct(QfRf)), and the degree of hydrophilicity for chalcopyrite was higher when the value of charge transfer resistance Rct. was greater. The optimum potential range for the floatation of chalcopyrite in collectorless solution at pH value of 6.97 was between OCP (0.165V) and 0.35V.

  18. Development of polymer lab-on-a-chip (LOC) for oxidation-reduction potential (ORP) measurement.

    PubMed

    Jang, A; Lee, K K; Bishop, P L; Kim, I S; Ahn, C H

    2011-01-01

    Reverse osmosis (RO) desalination has been recognized as a promising method to solve the water shortage problem. Nevertheless, since it is energy intensive and has many problems associated with biofouling/fouling of RO membranes in RO plants, its commercial acceptance is still slow. Especially, as high levels of oxidizing agents negatively affect RO membrane efficiency and life span. So, there is a need to develop sensitive, selective, portable and rapid methods to determine oxidation-reduction potential (ORP) in feed solution. For developing a polymer ORP lab-on-a-chip (LOC), a microchannel patterned on a polymer substrate was successfully filled with 800 nm diameter silica beads using self-assembly bead packing technology. The measured ORPs using the three kinds of redox potential solutions were typically slightly lower than those of the nominal redox potential. But, all of the measurements should be deemed acceptable. The ORP LOC has also a much shorter response time than the conventional potentiometric sensor.

  19. Brassinosteroid Ameliorates Zinc Oxide Nanoparticles-Induced Oxidative Stress by Improving Antioxidant Potential and Redox Homeostasis in Tomato Seedling

    PubMed Central

    Li, Mengqi; Ahammed, Golam J.; Li, Caixia; Bao, Xiao; Yu, Jingquan; Huang, Chunlei; Yin, Hanqin; Zhou, Jie

    2016-01-01

    In the last few decades use of metal-based nanoparticles (MNPs) has been increased significantly that eventually contaminating agricultural land and limiting crop production worldwide. Moreover, contamination of food chain with MNPs has appeared as a matter of public concern due to risk of potential health hazard. Brassinosteroid has been shown to play a critical role in alleviating heavy metal stress; however, its function in relieving zinc oxide nanoparticles (ZnO NPs)-induced phytotoxicity remains unknown. In this study, we investigated the potential role of 24-epibrassinolide (BR) in mitigating ZnO NPs-induced toxicity in tomato seedlings. Seedling growth, biomass production, and root activity gradually decreased, but Zn accumulation increased with increasing ZnO NPs concentration (10–100 mg/L) in growth media (½ MS). The augmentation of BR (5 nM) in media significantly ameliorated 50 mg/L ZnO NPs-induced growth inhibition. Visualization of hydrogen peroxide (H2O2), and quantification of H2O2 and malondialdehyde (MDA) in tomato roots confirmed that ZnO NPs induced an oxidative stress. However, combined treatment with BR and ZnO NPs remarkably reduced concentration of H2O2 and MDA as compared with ZnO NPs only treatment, indicating that BR supplementation substantially reduced oxidative stress. Furthermore, the activities of key antioxidant enzymes such as superoxide dismutase (SOD), catalase, ascorbate peroxidase and glutathione reductase were increased by combined treatment of BR and ZnO NPs compared with ZnO NPs only treatment. BR also increased reduced glutathione (GSH), but decreased oxidized glutathione (GSSG)] and thus improved cellular redox homeostasis by increasing GSH:GSSG ratio. The changes in relative transcript abundance of corresponding antioxidant genes such as Cu/Zn SOD, CAT1, GSH1, and GR1 were in accordance with the changes in those antioxidants under different treatments. More importantly, combined application of BR and ZnO NPs

  20. Potential role of green tea catechins in the management of oxidative stress-associated infertility.

    PubMed

    Roychoudhury, Shubhadeep; Agarwal, Ashok; Virk, Gurpriya; Cho, Chak-Lam

    2017-05-01

    Reactive oxygen species (ROS) are present in low concentrations in the genital tracts of males and females. Excessive ROS lead to oxidative stress, which damages DNA, lipids and proteins. Such molecular changes result in compromised vitality, increased morphological defects and decreased sperm motility in the male. In the female, oxidative stress interferes with oocyte maturation, and may inhibit in-vitro maturation of the oocyte. Recently, green tea supplementation has been reported to possess properties that may improve the quality of male and female gametes largely due to the ability of catechin polyphenols to quench ROS. Epigallocatechin-3-gallate (EGCG) is considered the most promising bioactive compound in green tea due to its strong antioxidant activity. The unique property of green tea catechins may potentially improve reproductive health and pose an important research area. We present a comprehensive overview on the effects and potential roles of green tea catechins on oxidative stress in male and female reproduction and fertility. In this review, possible mechanisms of action are highlighted to better understand the potential use of green tea catechins in the reduction of oxidative stress and its associated beneficial effects in the clinical setting. Copyright © 2017 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  1. Effects of Aftermarket Control Technologies on Gas and Particle Phase Oxidative Potential from Diesel Engine Emissions.

    PubMed

    Pavlovic, Jelica; Holder, Amara L; Yelverton, Tiffany L B

    2015-09-01

    Particulate matter (PM) originating from diesel combustion is a public health concern due to its association with adverse effects on respiratory and cardiovascular diseases and lung cancer. This study investigated emissions from three stationary diesel engines (gensets) and varying power output (230 kW, 400 kW, and 600 kW) at 50% and 90% load to determine concentrations of gaseous (GROS) and PM reactive oxygen species (PMROS). In addition, the influence of three modern emission control technologies on ROS emissions was evaluated: active and passive diesel particulate filters (A-DPF and P-DPF) and a diesel oxidation catalyst (DOC). PMROS made up 30-50% of the total ROS measured without aftermarket controls. All applied controls removed PMROS by more than 75% on average. However, the oxidative potential of PM downstream of these devices was not diminished at the same rate and particles surviving the A-PDF had an even higher oxidative potential on a per PM mass basis compared to the particles emitted by uncontrolled gensets. Further, the GROS as compared to PMROS emissions were not reduced with the same efficiency (<36%). GROS concentrations were highest with the DOC in use, indicating continued formation of GROS with this control. Correlation analyses showed that PMROS and to a lesser extent GROS have a good correlation with semivolatile organic carbon (OC1) subfraction. In addition, results suggest that chemical composition, rather than PM size, is responsible for differences in the PM oxidative potential.

  2. The Charcot-Marie-Tooth type 2A gene product, Mfn2, up-regulates fuel oxidation through expression of OXPHOS system.

    PubMed

    Pich, Sara; Bach, Daniel; Briones, Paz; Liesa, Marc; Camps, Marta; Testar, Xavier; Palacín, Manuel; Zorzano, Antonio

    2005-06-01

    Mitofusin-2 (Mfn2) is a mitochondrial membrane protein that participates in mitochondrial fusion in mammalian cells and mutations in the Mfn2 gene cause Charcot-Marie-Tooth neuropathy type 2A. Here, we show that Mfn2 loss-of-function inhibits pyruvate, glucose and fatty acid oxidation and reduces mitochondrial membrane potential, whereas Mfn2 gain-of-function increases glucose oxidation and mitochondrial membrane potential. As to the mechanisms involved, we have found that Mfn2 loss-of-function represses nuclear-encoded subunits of OXPHOS complexes I, II, III and V, whereas Mfn2 overexpression induced the subunits of complexes I, IV and V. Obesity-induced Mfn2 deficiency in rat skeletal muscle was also associated with a decrease in the subunits of complexes I, II, III and V. In addition, the effect of Mfn2 overexpression on mitochondrial metabolism was mimicked by a truncated Mfn2 mutant that is inactive as a mitochondrial fusion protein. Our results indicate that Mfn2 triggers mitochondrial energization, at least in part, by regulating OXPHOS expression through signals that are independent of its role as a mitochondrial fusion protein.

  3. The random-coil 'C' fragment of the dihydropyridine receptor II-III loop can activate or inhibit native skeletal ryanodine receptors.

    PubMed Central

    Haarmann, Claudia S; Green, Daniel; Casarotto, Marco G; Laver, Derek R; Dulhunty, Angela F

    2003-01-01

    The actions of peptide C, corresponding to (724)Glu-Pro(760) of the II-III loop of the skeletal dihydropyridine receptor, on ryanodine receptor (RyR) channels incorporated into lipid bilayers with the native sarcoplasmic reticulum membrane show that the peptide is a high-affinity activator of native skeletal RyRs at cytoplasmic concentrations of 100 nM-10 microM. In addition, we found that peptide C inhibits RyRs in a voltage-independent manner when added for longer times or at higher concentrations (up to 150 microM). Peptide C had a random-coil structure indicating that it briefly assumes a variety of structures, some of which might activate and others which might inhibit RyRs. The results suggest that RyR activation and inhibition by peptide C arise from independent stochastic processes. A rate constant of 7.5 x 10(5) s(-1).M(-1) was obtained for activation and a lower estimate for the rate constant for inhibition of 5.9 x 10(3) s(-1).M(-1). The combined actions of peptide C and peptide A (II-III loop sequence (671)Thr-Leu(690)) showed that peptide C prevented activation but not blockage of RyRs by peptide A. We suggest that the effects of peptide C indicate functional interactions between a part of the dihydropyridine receptor and the RyR. These interactions could reflect either dynamic changes that occur during excitation-contraction coupling or interactions between the proteins at rest. PMID:12620094

  4. Thyroid Function in Women after Multimodal Treatment for Breast Cancer Stage II/III: Comparison With Controls From a Population Sample

    SciTech Connect

    Reinertsen, Kristin Valborg; Cvancarova, Milada; Wist, Erik; Bjoro, Trine; Dahl, Alv A.; Danielsen, Turi; Fossa, Sophie D.

    2009-11-01

    Purpose: A possible association between thyroid diseases (TD) and breast cancer (BC) has been debated. We examined prevalence and development of TD in women after multimodal treatment for Stage II/III BC compared with women from a general population. Secondarily, we explored the impact of two different radiotherapy (RT) techniques (standardized field arrangements vs. computed tomography [CT]-based dose planning) on TD in BC patients examined 35-120 months after primary BC treatment. Methods and Materials: A total of 403 BC patients completed a questionnaire about TD and had blood samples taken for analyses of thyroid function. All had undergone postoperative RT with or without (2%) adjuvant systemic treatment. The results in the BC patients were compared with a cancer-free, age-matched control group from a general population (CGr). Results: There was higher prevalence of self-reported hypothyroidism in the BC patients as compared with the CGr (18% vs. 6%, p < 0.001). The raised prevalence was predominantly due to a substantial increase in the development of hypothyroidism after BC diagnosis, whereas the prevalence of hypothyroidism before BC diagnosis was similar to that observed in the CGr. Patients treated with CT-based RT showed a trend for increased post-BC development of hypothyroidism as compared with those treated with standardized field arrangements (p = 0.08). Conclusions: Hypothyroidism is significantly increased in women after multimodal treatment for Stage II/III BC. Radiation to the thyroid gland may be a contributing factor. BC patients should be routinely screened for hypothyroidism.

  5. Predictors of Long-Term Quality of Life for Survivors of Stage II/III Rectal Cancer in the Cancer Care Outcomes Research and Surveillance Consortium

    PubMed Central

    Charlton, Mary E.; Stitzenberg, Karyn B.; Lin, Chi; Schlichting, Jennifer A.; Halfdanarson, Thorvardur R.; Juarez, Grelda Yazmin; Pendergast, Jane F.; Chrischilles, Elizabeth A.; Wallace, Robert B.

    2015-01-01

    Purpose: Many patients do not receive guideline-recommended neoadjuvant chemoradiotherapy for resectable rectal cancer. Little is known regarding long-term quality of life (QOL) associated with various treatment approaches. Our objective was to determine patient characteristics and subsequent QOL associated with treatment approach. Methods: Our study was a geographically diverse population- and health system–based cohort study that included adults age 21 years or older with newly diagnosed stage II/III rectal cancer who were recruited from 2003 to 2005. Eligible patients were contacted 1 to 4 months after diagnosis and asked to participate in a telephone survey and to consent to medical record review, with separate follow-up QOL surveys conducted 1 and 7 years after diagnosis. Results: Two hundred thirty-nine patients with stage II/III rectal cancer were included in this analysis. Younger age (< 65 v ≥ 65 years: odds ratio, 2.49; 95% CI, 1.33 to 4.65) was significantly associated with increased odds of receiving neoadjuvant or adjuvant chemoradiotherapy. The adjuvant chemoradiotherapy group had significantly worse mean EuroQol-5D (range, 0 to 1) and Short Form-12 physical health component scores (standardized mean, 50) at 1-year follow-up than the neoadjuvant chemoradiotherapy group (0.75 v 0.85; P = .002; 37.2 v 43.3; P = .01, respectively) and the group that received only one or neither form of treatment (0.75 v 0.85; P = .02; 37.2 v 45.1; P = .008, respectively). Conclusion: Neoadjuvant treatment may result in better QOL and functional status 1 year after diagnosis. Further evaluation of patient and provider reasons for not pursuing neoadjuvant therapy is necessary to determine how and where to target process improvement and/or education efforts to ensure that patients have access to recommended treatment options. PMID:26080831

  6. Effect of CXCR4 and CD133 co-expression on the prognosis of patients with stage II~III colon cancer.

    PubMed

    Li, Xiao-Feng; Guo, Xiao-Guang; Yang, Yong-Yan; Liu, Ai-Yong

    2015-01-01

    To explore the relationship between CXCR4, CD133 co-expression and clinicopathological features as well as prognosis of patients with phase II~III colon cancer. Forty-nine paraffin-embedded samples of tumor tissue and epithelial tissue adjacent to cancer were collected from patients with colon cancer undergoing radical surgery in Baotou Cancer Hospital from January, 2010 to June, 2011. CXCR4 and CD133 expression was detected using immunohistochemistry and its relationship with clinicopathological features and the 3-year survival rate was analyzed. In the tumor tissue and colonic epithelial tissue adjacent to cancer, the positive expression rates of CXCR4 were respectively 61.2% (30/49) and 8.16% (4/49), while those of CD133 being 36.7% (18/49) and 6.12% (3/49). CXCR4 and CD133 expression in tumor tissue was not related to patient age, gender, primary focal sites, tumor size, TNM staging, histological type, tumor infiltration depth and presence or absence of lymphatic metastasis, but CXCR4 and CD133 co-expression was associated with TNM staging and lymphatic metastasis. The 3-year survival rate of patients with CXCR4 and CD133 co-expression was 27.3% (3/11), and that of the remainderwas 76.3% (29/38), the difference being significant (χ2=7.0206, p=0.0081). CXCR4 and CD133 co-expression may be a risk factor for poor prognosis of patients with stage II~III colon cancer.

  7. Assessing the oxidative potential of isoprene-derived epoxides and secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Kramer, Amanda J.; Rattanavaraha, Weruka; Zhang, Zhenfa; Gold, Avram; Surratt, Jason D.; Lin, Ying-Hsuan

    2016-04-01

    Fine particulate matter (PM2.5) is known to contribute to adverse health effects, such as asthma, cardiopulmonary disease, and lung cancer. Secondary organic aerosol (SOA) is a major component of PM2.5 and can be enhanced by atmospheric oxidation of biogenic volatile organic compounds in the presence of anthropogenic pollutants, such as nitrogen oxides (NOx) and sulfur dioxide. However, whether biogenic SOA contributes to adverse health effects remains unclear. The objective of this study was to assess the potential of isoprene-derived epoxides and SOA for generating reactive oxygen species (ROS) in light of the recent recognition that atmospheric oxidation of isoprene in the presence of acidic sulfate aerosol is a major contributor to the global SOA burden. The dithiothreitol (DTT) assay was used to characterize the ROS generation by the isoprene-derived epoxides, trans-β-isoprene epoxydiol (trans-β-IEPOX) and methacrylic acid epoxide (MAE), and their hydrolysis products, the 2-methyltetrol diastereomers (2-MT), 2-methylglyceric acid (2-MG), their organosulfate derivatives, as well as an isoprene-derived hydroxyhydroperoxide (ISOPOOH). In addition, ROS generation potential was evaluated for total SOA produced from photooxidation of isoprene and methacrolein (MACR) as well as from the reactive uptake of trans-β-IEPOX and MAE onto acidified sulfate aerosol. The high-NOx regime, which yields 2-MG-, MAE- and MACR-derived SOA has a higher ROS generation potential than the low-NOx regime, which yields 2-MT, IEPOX- and isoprene-derived SOA. ISOPOOH has an ROS generation potential similar to 1,4-naphthoquinone (1,4-NQ), suggesting a significant contribution of aerosol-phase organic peroxides to PM oxidative potential. MAE- and MACR-derived SOA show equal or greater ROS generation potential than reported in studies on diesel exhaust PM, highlighting the importance of a comprehensive investigation of the toxicity of isoprene-derived SOA.

  8. Temperature response of methane oxidation and production potentials in peatland ecosystems across Finland

    NASA Astrophysics Data System (ADS)

    Welti, Nina; Korrensalo, Aino; Kerttula, Johanna; Maljanen, Marja; Uljas, Salli; Lohila, Annalea; Laine, Anna; Vesala, Timo; Elliott, David; Tuittila, Eeva-Stiina

    2016-04-01

    It has been suggested that the ecosystems located in the high latitudes are especially sensitive to warming. Therefore, we compared 14 peatland systems throughout Finland along a latitudinal gradient from 69°N to 61°N to examine the response of methane production and methane oxidation with warming climate. Peat samples were taken at the height of the growing season in 2015 from 0 - 10cm below the water table depth. The plant communities in sampling locations were described by estimating cover of each plant species and pH of water was measured. Upon return to the lab, we made two parallel treatments, under anoxic and oxic conditions in order to calculate the CH4 production and consumption potentials of the peat and used three temperatures, 4°C, 17.5°C, and 30°C to examine the temperature effect on the potentials. We hypothesized that there will be an observable response curve in CH4 production and oxidation relative to temperature with a greater response with increasing latitude. In general, increasing temperature increased the potential for CH4 production and oxidation, at some sites, the potential was highest at 17.5°C, indicating that there is an optimum temperature threshold for the in situ methane producing and oxidizing microbial communities. Above this threshold, the peat microbial communities are not able to cope with increasing temperature. This is especially noticeable for methane oxidation at sites above 62°N. As countries are being expected to adequately account for their greenhouse gas budgets with increasing temperature models, knowing where the temperature threshold exists is of critical importance.

  9. Fluctuation Analysis of Redox Potential to Distinguish Microbial Fe(II) Oxidation

    NASA Astrophysics Data System (ADS)

    Enright, A. M. L.; Ferris, F. G.

    2016-11-01

    We developed a novel method for distinguishing abiotic and biological iron oxidation in liquid media using oxidation-reduction (redox) potential time series data. The instrument and processing algorithm were tested by immersing the tip of a Pt electrode with an Ag-AgCl reference electrode into an active iron-oxidizing biofilm in a groundwater discharge zone, as well as in two abiotic systems: a killed sample and a chemical control from the same site. We used detrended fluctuation analysis to characterize average root mean square fluctuation behavior, which was distinct in the live system. The calculated α value scaling exponents determined by detrended fluctuation analysis were significantly different at p < 0.001. This indicates that time series of electrode response data may be used to distinguish live and abiotic chemical reaction pathways. Due to the simplicity, portability, and small size, it may be suitable for characterization of extraterrestrial environments where water has been observed, such as Mars and Europa.

  10. Preparation and characterization of an iron oxide-hydroxyapatite nanocomposite for potential bone cancer therapy.

    PubMed

    Sneha, Murugesan; Sundaram, Nachiappan Meenakshi

    2015-01-01

    Recently, multifunctional magnetic nanostructures have been found to have potential applications in biomedical and tissue engineering. Iron oxide nanoparticles are biocompatible and have distinctive magnetic properties that allow their use in vivo for drug delivery and hyperthermia, and as T2 contrast agents for magnetic resonance imaging. Hydroxyapatite is used frequently due to its well-known biocompatibility, bioactivity, and lack of toxicity, so a combination of iron oxide and hydroxyapatite materials could be useful because hydroxyapatite has better bone-bonding ability. In this study, we prepared nanocomposites of iron oxide and hydroxyapatite and analyzed their physicochemical properties. The results suggest that these composites have superparamagnetic as well as biocompatible properties. This type of material architecture would be well suited for bone cancer therapy and other biomedical applications.

  11. How surface potential determines the kinetics of the first hole transfer of photocatalytic water oxidation.

    PubMed

    Waegele, Matthias M; Chen, Xihan; Herlihy, David M; Cuk, Tanja

    2014-07-30

    Interfacial hole transfer between n-SrTiO3 and OH(-) was investigated by surface sensitive transient optical spectroscopy of an in situ photoelectrochemical cell during water oxidation. The kinetics reveal a single rate constant with an exponential dependence on the surface hole potential, spanning time scales from 3 ns to 8 ps over a ≈1 V increase. A voltage- and laser illumination-induced process moves the valence band edge at the n-type semiconductor/water interface to continuously change the surface hole potential. This single step of the water oxidation reaction is assigned to the first hole transfer h(+) + OH(-) → OH(•). The kinetics quantify how much a change in the free energy difference driving this first hole transfer reduces the activation barrier. They are also used to extrapolate the kinetic rate due to the activation barrier when that free energy difference is zero, or the Nernstian potential. This is the first time transient spectroscopy has enabled the separation of the first hole transfer from the full four hole transfer cycle and a direct determination of these two quantities. The Nernstian potential for OH(-)/OH(•) is also suggested, in rough agreement with gas-phase studies. The observation of a distinct, much longer time scale upon picosecond hole transfer to OH(-) suggests that a dominant, more stable intermediate of the water oxidation reaction, possibly a surface bound oxo, may result.

  12. Microbial Fe(III) oxide reduction potential in Chocolate Pots hot spring, Yellowstone National Park.

    PubMed

    Fortney, N W; He, S; Converse, B J; Beard, B L; Johnson, C M; Boyd, E S; Roden, E E

    2016-05-01

    Chocolate Pots hot springs (CP) is a unique, circumneutral pH, iron-rich, geothermal feature in Yellowstone National Park. Prior research at CP has focused on photosynthetically driven Fe(II) oxidation as a model for mineralization of microbial mats and deposition of Archean banded iron formations. However, geochemical and stable Fe isotopic data have suggested that dissimilatory microbial iron reduction (DIR) may be active within CP deposits. In this study, the potential for microbial reduction of native CP Fe(III) oxides was investigated, using a combination of cultivation dependent and independent approaches, to assess the potential involvement of DIR in Fe redox cycling and associated stable Fe isotope fractionation in the CP hot springs. Endogenous microbial communities were able to reduce native CP Fe(III) oxides, as documented by most probable number enumerations and enrichment culture studies. Enrichment cultures demonstrated sustained DIR driven by oxidation of acetate, lactate, and H2 . Inhibitor studies and molecular analyses indicate that sulfate reduction did not contribute to observed rates of DIR in the enrichment cultures through abiotic reaction pathways. Enrichment cultures produced isotopically light Fe(II) during DIR relative to the bulk solid-phase Fe(III) oxides. Pyrosequencing of 16S rRNA genes from enrichment cultures showed dominant sequences closely affiliated with Geobacter metallireducens, a mesophilic Fe(III) oxide reducer. Shotgun metagenomic analysis of enrichment cultures confirmed the presence of a dominant G. metallireducens-like population and other less dominant populations from the phylum Ignavibacteriae, which appear to be capable of DIR. Gene (protein) searches revealed the presence of heat-shock proteins that may be involved in increased thermotolerance in the organisms present in the enrichments as well as porin-cytochrome complexes previously shown to be involved in extracellular electron transport. This analysis offers

  13. Effect of Water Potential on Growth and Iron Oxidation by Thiobacillus ferrooxidans

    PubMed Central

    Brock, Thomas D.

    1975-01-01

    The effect of water potential on the growth of two strains of Thiobacillus ferroxidans was determined by adding defined amounts of sodium chloride or glycerol to the culture medium. The two strains differed slightly, and the most tolerant strain had a minimum water potential for growth of -15 to -32 bars when sodium chloride was used and -6 bars when glycerol was used. In another approach, the limiting water potential was determined by equilibrating small amounts of culture medium with atmospheres of relative humidities equivalent to specific water potentials, and the ability of the organism to grow and oxidize ferrous iron was determined. Under these conditions, which are analogous to those which might control water potential in a coal refuse pile or copper leaching dump, the lower limit at which iron oxidation occurred was -23 bars. The water potential of some coal refuse materials in which T. ferrooxidans was present were determined, and it was found that the water potentials at which the organism was active in these habitats were similar to those at which it was able to grow in culture. However, marked variation in water potential of coal refuse materials was found, presumably due to differences in clays and organic materials, and some coal refuse materials would probably never have water potentials at which the organism could grow. Some literature on the water potentials in copper leach dumps is reviewed, and it is concluded that control of water potential is essential to maximize the success of leaching operations. Because adequate drainage is necessary in a leach dump to ensure sufficient aeration, in many cases water availability in leach dumps may restrict the development of the bacterium necessary for the process. PMID:1124922

  14. Exercise and oxidative stress: potential effects of antioxidant dietary strategies in sports.

    PubMed

    Pingitore, Alessandro; Lima, Giuseppina Pace Pereira; Mastorci, Francesca; Quinones, Alfredo; Iervasi, Giorgio; Vassalle, Cristina

    2015-01-01

    Free radicals are produced during aerobic cellular metabolism and have key roles as regulatory mediators in signaling processes. Oxidative stress reflects an imbalance between production of reactive oxygen species and an adequate antioxidant defense. This adverse condition may lead to cellular and tissue damage of components, and is involved in different physiopathological states, including aging, exercise, inflammatory, cardiovascular and neurodegenerative diseases, and cancer. In particular, the relationship between exercise and oxidative stress is extremely complex, depending on the mode, intensity, and duration of exercise. Regular moderate training appears beneficial for oxidative stress and health. Conversely, acute exercise leads to increased oxidative stress, although this same stimulus is necessary to allow an up-regulation in endogenous antioxidant defenses (hormesis). Supporting endogenous defenses with additional oral antioxidant supplementation may represent a suitable noninvasive tool for preventing or reducing oxidative stress during training. However, excess of exogenous antioxidants may have detrimental effects on health and performance. Whole foods, rather than capsules, contain antioxidants in natural ratios and proportions, which may act in synergy to optimize the antioxidant effect. Thus, an adequate intake of vitamins and minerals through a varied and balanced diet remains the best approach to maintain an optimal antioxidant status. Antioxidant supplementation may be warranted in particular conditions, when athletes are exposed to high oxidative stress or fail to meet dietary antioxidant requirements. Aim of this review is to discuss the evidence on the relationship between exercise and oxidative stress, and the potential effects of dietary strategies in athletes. The differences between diet and exogenous supplementation as well as available tools to estimate effectiveness of antioxidant intake are also reported. Finally, we advocate the need

  15. Ranolazine, a partial fatty acid oxidation inhibitor, its potential benefit in angina and other cardiovascular disorders.

    PubMed

    Bhandari, Bharti; Subramanian, L

    2007-01-01

    Chronic Angina resistant to medical treatment with hemodynamically acting agents is a major problem in clinical setup. For such patients, large number of clinical trials have documented the beneficial effect of Ranolazine. It acts as an anti-anginal agent that controls myocardial ischemia through intracellular metabolic changes. Ranolazine is a partial fatty acid oxidation inhibitor which shifts cardiac energy metabolism from fatty acid oxidation to glucose oxidation. Since the oxidation of glucose requires less oxygen than the oxidation of fatty acids, ranolazine can help maintain myocardial function in times of ischemia. In addition, ranolazine has minimal effect on blood pressure and heart rate. Ranolazine, by inhibiting cellular ionic channels, prolongs the corrected QT interval. However, ranolazine has not yet been associated with any incidences of ventricular arrhythmia. Other possible mechanism by which Ranolazine could act is by reducing the formation of reactive oxygen species (ROS) and improves reperfusion mechanical function. Ranolazine has been approved by US FDA for the treatment of chronic angina pectoris in combination with amlodipine, beta-blockers or nitrates in patients who do not show adequate response to other anti-anginals. Ranolazine is a metabolic modulator that is being developed by CV Therapeutics (CVT), under license from Roche (formerly Syntex), as a potential treatment for angina. Ranolazine is available as brand name 'Ranexa' as extended release oral tablets. This review focuses on the clinical effects, the mechanism of actions, drug interactions and beneficial effects of Ranolazine in chronic angina and other cardiometabolic disorders.

  16. Potential methane production and methane oxidation rates in peatland ecosystems of the Appalachian Mountains, United States

    SciTech Connect

    Yavitt, J.B.; Lang, G.E.; Downey, D.M. )

    1988-09-01

    Potential rates of methane production and carbon dioxide production were measured on 11 dates in 1986 in peat from six plant communities typical of moss-dominated peatlands in the Appalachian Mountains. Annual methane production ranged from 2.7 to 17.5 mol/sq m, and annual carbon dioxide production ranged from 30.6 to 79.0 mol/sq m. The wide range in methane production values among the communities found within a single peatland indicates that obtaining one production value for a peatland may not be appropriate. Low temperature constrained the potential for methane production in winter, while the chemical quality of the peat substrate appears to control methane production in the summer. Methane oxidation was measured throughout the peat profile to a depth of 30 cm. Values for methane oxidation ranged from 0.08 to 18.7 microM/hr among the six plant communities. Aerobic methane-oxidizing bacteria probably mediated most of the activity. On a daily basis during the summer, between 11 and 100% of the methane produced is susceptible to oxidation within the peat column. Pools of dissolved methane and dissolved carbon dioxide in pore waters were less than 0.2 and less than 1.0 mol/sq m, respectively, indicating that methane does not accumulate in the pore waters. Peatlands have been considered as an important source of biologically produced methane. Despite the high rates of methane production, the high rates of methane oxidation dampen the potential emission of methane to the atmosphere. 41 refs., 7 figs., 4 tabs.

  17. Bacterial Fe(II) oxidation distinguished by long-range correlation in redox potential

    NASA Astrophysics Data System (ADS)

    Enright, Allison M. L.; Ferris, F. Grant

    2016-05-01

    The kinetics of bacterial Fe(II) oxidation was investigated 297 m underground at the Äspö Hard Rock Laboratory (near Oskarshamn, Sweden) under steady state groundwater flow conditions in a flow-through cell containing well-developed flocculent mats of bacteriogenic iron oxides (BIOS). Pseudo first-order rate constants of 0.004 min-1 and 0.009 min-1 were obtained for chemical and bacterial Fe(II) oxidation, respectively, based on the 104 min retention time of groundwater in the flow cell, inlet Fe(II) concentration of 21.0 ± 0.5 µm, outlet Fe(II) concentration of 8.5 ± 0.7 µm, as well as constant pH = - log H+ of 7.42 ± 0.01, dissolved O2 concentration of 0.11 ± 0.01 mg/L, and groundwater temperature of 12.4 ± 0.1°C. Redox potential was lower at the BIOS-free inlet (-135.4 ± 1.16 mV) compared to inside BIOS within the flow cell (-112.6 ± 1.91 mV), consistent with the Nernst relationship and oxidation of Fe(II) to Fe(III). Further evaluation of the redox potential time series data using detrended fluctuation analysis (DFA) revealed power law scaling in the amplitude of fluctuations over increasing intervals of time with significantly different (p < 0.01) DFA α scaling exponents of 1.89 ± 0.03 for BIOS and 1.67 ± 0.06 at the inlet. These α values not only signal the presence of long-range correlation in the redox potential time series measurements but also distinguish between the slower rate of chemical Fe(II) oxidation at the inlet and faster rate accelerated by FeOB in BIOS.

  18. Potentials and challenges of integration for complex metal oxides in CMOS devices and beyond

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Pham, C.; Chang, J. P.

    2015-02-01

    This review focuses on recent accomplishments on complex metal oxide based multifunctional materials and the potential they hold in advancing integrated circuits. It begins with metal oxide based high-κ materials to highlight the success of their integration since 45 nm complementary metal-oxide-semiconductor (CMOS) devices. By simultaneously offering a higher dielectric constant for improved capacitance as well as providing a thicker physical layer to prevent the quantum mechanical tunnelling of electrons, high-κ materials have enabled the continued down-scaling of CMOS based devices. The most recent technology driver has been the demand to lower device power consumption, which requires the design and synthesis of novel materials, such as complex metal oxides that exhibit remarkable tunability in their ferromagnetic, ferroelectric and multiferroic properties. These properties make them suitable for a wide variety of applications such as magnetoelectric random access memory, radio frequency band pass filters, antennae and magnetic sensors. Single-phase multiferroics, while rare, offer unique functionalities which have motivated much scientific and technological research to ascertain the origins of their multiferroicity and their applicability to potential devices. However, due to the weak magnetoelectric coupling for single-phase multiferroics, engineered multiferroic composites based on magnetostrictive ferromagnets interfacing piezoelectrics or ferroelectrics have shown enhanced multiferroic behaviour from effective strain coupling at the interface. In addition, nanostructuring of the ferroic phases has demonstrated further improvement in the coupling effect. Therefore, single-phase and engineered composite multiferroics consisting of complex metal oxides are reviewed in terms of magnetoelectric coupling effects and voltage controlled ferromagnetic properties, followed by a review on the integration challenges that need to be overcome to realize the

  19. Potential Therapeutic Role of L-Carnitine in Skeletal Muscle Oxidative Stress and Atrophy Conditions

    PubMed Central

    Montesano, Anna; Senesi, Pamela; Luzi, Livio; Benedini, Stefano; Terruzzi, Ileana

    2015-01-01

    The targeting of nutraceutical treatment to skeletal muscle damage is an emerging area of research, driven by the need for new therapies for a range of muscle-associated diseases. L-Carnitine (CARN) is an essential nutrient and plays a key role in mitochondrial β-oxidation and in the ubiquitin-proteasome system regulation. As a dietary supplement to improve athletic performance, CARN has been studied for its potential to enhance β-oxidation. However, CARN effects on myogenesis, mitochondrial activity, and hypertrophy process are not completely elucidated. This in vitro study aims to investigate CARN role on skeletal muscle remodeling, differentiation process, and myotubes formation. We analyzed muscle differentiation and morphological features in C2C12 myoblasts exposed to 5 mM CARN. Our results showed that CARN was able to accelerate C2C12 myotubes formation and induce morphological changes, characterizing the start of hypertrophy process. In addition, CARN improved AKT activation and downstream cellular signaling pathways involved in skeletal muscle atrophy process prevention. Also, CARN positively regulated the pathways involved in oxidative stress defense. In this work, we provide an interesting novel mechanism of the potential therapeutic use of CARN to treat pathological conditions characterized by skeletal muscle morphological and functional impairment, oxidative stress production, and atrophy process in aging. PMID:25838869

  20. Chemical characteristics and oxidative potential of particulate matter emissions from gasoline, diesel, and biodiesel cars.

    PubMed

    Cheung, Ka Lam; Polidori, Andrea; Ntziachristos, Leonidas; Tzamkiozis, Theodoros; Samaras, Zissis; Cassee, Flemming R; Gerlofs, Miriam; Sioutas, Constantinos

    2009-08-15

    Three light-duty vehicles in five different configurations [a Honda Accord operating with diesel with a closed-coupled oxidation catalyst and an underfloor catalyst replaced in some tests with a diesel particle filter (DPF), a Toyota Corolla operating with gasoline, and a VW Golf alternatively operating with petrodiesel or biodiesel] were tested in a dynamometer facility to develop an improved understanding of the factors affecting the toxicity of particulate exhaust emissions. The vehicles were tested using a variety of real-world driving cycles, more than the certification test (New European Driving Cycle). Particle samples were collected and analyzed for elemental and organic carbon (EC and OC, respectively), water soluble and water insoluble organic carbon (WSOC and WISOC, respectively), and inorganic ions, and the emission rates (mg/km) for each vehicle/configuration were determined. A dithiothreitol (DTT) assay was used to assess the oxidative potential of the particulate matter (PM) samples. The DPF-equipped diesel and gasoline vehicles were characterized by the lowest overall PM mass emissions, while the diesel and biodiesel cars produced the most potent exhaust in terms of oxidative activity. When the DPF was fitted on the Honda Accord diesel vehicle, the mass emission rates and distance-based oxidative potential were both decreased by 98%, compared to the original configuration. Correlation analysis showed that the DTT consumption rate was highly associated with WSOC, WISOC, and OC (R = 0.98, 0.93, and 0.94, respectively), consistent with previous findings.

  1. High rates of anaerobic methane oxidation in freshwater wetlands reduce potential atmospheric methane emissions.

    PubMed

    Segarra, K E A; Schubotz, F; Samarkin, V; Yoshinaga, M Y; Hinrichs, K-U; Joye, S B

    2015-06-30

    The role of anaerobic oxidation of methane (AOM) in wetlands, the largest natural source of atmospheric methane, is poorly constrained. Here we report rates of microbially mediated AOM (average rate=20 nmol cm(-3) per day) in three freshwater wetlands that span multiple biogeographical provinces. The observed AOM rates rival those in marine environments. Most AOM activity may have been coupled to sulphate reduction, but other electron acceptors remain feasible. Lipid biomarkers typically associated with anaerobic methane-oxidizing archaea were more enriched in (13)C than those characteristic of marine systems, potentially due to distinct microbial metabolic pathways or dilution with heterotrophic isotope signals. On the basis of this extensive data set, AOM in freshwater wetlands may consume 200 Tg methane per year, reducing their potential methane emissions by over 50%. These findings challenge precepts surrounding wetland carbon cycling and demonstrate the environmental relevance of an anaerobic methane sink in ecosystems traditionally considered strong methane sources.

  2. Improving carbon dioxide yields and cell efficiencies for ethanol oxidation by potential scanning

    NASA Astrophysics Data System (ADS)

    Majidi, Pasha; Pickup, Peter G.

    2014-12-01

    An ethanol electrolysis cell with aqueous ethanol supplied to the anode and nitrogen at the cathode has been operated under potential cycling conditions in order to increase the yield of carbon dioxide and thereby increase cell efficiency relative to operation at a fixed potential. At ambient temperature, faradaic yields of CO2 as high as 26% have been achieved, while only transient CO2 production was observed at constant potential. Yields increased substantially at higher temperatures, with maximum values at Pt anodes reaching 45% at constant potential and 65% under potential cycling conditions. Use of a PtRu anode increased the cell efficiency by decreasing the anode potential, but this was offset by decreased CO2 yields. Nonetheless, cycling increased the efficiency relative to constant potential. The maximum yields at PtRu and 80 °C were 13% at constant potential and 32% under potential cycling. The increased yields under cycling conditions have been attributed to periodic oxidative stripping of adsorbed CO, which occurs at lower potentials on PtRu than on Pt. These results will be important in the optimization of operating conditions for direct ethanol fuel cells and for the electrolysis of ethanol to produce clean hydrogen.

  3. Anti-atherosclerotic potential of gossypetin via inhibiting LDL oxidation and foam cell formation

    SciTech Connect

    Chen, Jing-Hsien; Tsai, Chia-Wen; Wang, Chi-Ping; Lin, Hui-Hsuan

    2013-10-15

    Gossypetin, a flavone originally isolated from Hibiscus species, has been shown to possess antioxidant, antimicrobial, and antimutagenic activities. Here, we investigated the mechanism(s) underlying the anti-atherosclerotic potential of gossypetin. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) scavenging activity assay showed that the addition of > 50 μM of gossypetin could scavenge over 50% of DPPH radicals. The inhibitory effects of gossypetin on the lipid and protein oxidation of LDL were defined by thiobarbituric acid reactive substance (TBARS) assay, the relative electrophoretic mobility (REM) of oxidized LDL (ox-LDL), and fragmentation of apoB in the Cu{sup 2+}-induced oxidation of LDL. Gossypetin showed potential in reducing ox-LDL-induced foam cell formation and intracellular lipid accumulation, and uptake ability of macrophages under non-cytotoxic concentrations. Molecular data showed that these influences of gossypetin might be mediated via peroxisome proliferator-activated receptor α (PPARα)/liver-X receptor α (LXRα)/ATP-binding cassette transporter A1 (ABCA1) and PPARγ/scavenger receptor CD36 pathways, as demonstrated by the transfection of PPARα siRNA or PPARγ expression vector. Our data implied that gossypetin regulated the PPAR signals, which in turn led to stimulation of cholesterol removal from macrophages and delay atherosclerosis. These results suggested that gossypetin potentially could be developed as an anti-atherosclerotic agent. - Highlights: • The anti-atherosclerotic effect of gossypetin in vitro was examined. • Gossypetin inhibited LDL oxidation. • Gossypetin showed potential in reducing on the formation of foam cells. • Gossypetin functions against ox-LDL through PPARa activation and PPARγ depression.

  4. In vitro anti-oxidant potential of new metabolites from Hypericum oblongifolium (Guttiferae).

    PubMed

    Raziq, Naila; Saeed, Muhammad; Ali, Muhammad Shaiq; Zafar, Salman; Ali, Muhammad Imran

    2015-01-01

    Phytochemical investigations on Hypericum oblongifolium led to the isolation of a flavone named folicitin (1) and a bicyclic conjugated lactone, folenolide (2) from the ethyl acetate fraction of methanolic extract. Both metabolites were characterised as new compounds based on detailed spectroscopic analyses. In vitro anti-oxidant potential of both the compounds was evaluated by the DPPH radical scavenging assay. Compound 1 exhibited significant antioxidant activity while compound 2 was found inactive.

  5. A molecular switch based on potential-induced changes of oxidation state.

    PubMed

    Chen, Fan; He, Jin; Nuckolls, Colin; Roberts, Tucker; Klare, Jennifer E; Lindsay, Stuart

    2005-03-01

    We have measured the conductance of a hepta-aniline oligomer attached to gold electrodes held under potential control in electrolyte. It increases fifteen-fold (to 5.3+/-0.4 nS) on oxidation from the leucoemeraldine form to the emeraldine salt. The single-molecule current-voltage characteristic, linear in toluene, displays negative differential resistance in an acidic electrolyte. The negative differential resistance is accounted for by modification of the local surface potential by the applied bias. These results connect electrochemical data directly to molecular electronic behavior in a two-terminal device.

  6. Oxidative potential of gas phase combustion emissions - An underestimated and potentially harmful component of air pollution from combustion processes

    NASA Astrophysics Data System (ADS)

    Stevanovic, S.; Vaughan, A.; Hedayat, F.; Salimi, F.; Rahman, M. M.; Zare, A.; Brown, R. A.; Brown, R. J.; Wang, H.; Zhang, Z.; Wang, X.; Bottle, S. E.; Yang, I. A.; Ristovski, Z. D.

    2017-06-01

    The oxidative potential (OP) of the gas phase is an important and neglected aspect of environmental toxicity. Whilst prolonged exposure to particulate matter (PM) associated reactive oxygen species (ROS) have been shown to lead to negative health effects, the potential for compounds in gas phase to cause similar effects is yet to be understood. In this study we describe: the significance of the gas phase OP generated through vehicle emissions; discuss the origin and evolution of species contributing to measured OP; and report on the impact of gas phase OP on human lung cells. The model aerosol for this study was exhaust emitted from a Euro III Common-rail diesel engine fuelled with different blends of diesel and biodiesel. The gas phase of these emissions was found to be potentially as hazardous as the particle phase. Fuel oxygen content was found to negatively correlate with the gas phase OP, and positively correlate with particle phase OP. This signifies a complex interaction between reactive species present in gas and particle phase. Furthermore, this interaction has an overarching effect on the OP of both particle and gas phase, and therefore the toxicity of combustion emissions.

  7. Charge-transfer interatomic potential for investigation of the thermal-oxidation growth process of silicon

    NASA Astrophysics Data System (ADS)

    Takamoto, So; Kumagai, Tomohisa; Yamasaki, Takahiro; Ohno, Takahisa; Kaneta, Chioko; Hatano, Asuka; Izumi, Satoshi

    2016-10-01

    A charge-transfer interatomic potential, based on the hybrid-Tersoff potential that incorporates a covalent-ionic mixed-bond nature, was developed to reproduce the growth process of the thermal oxidation of silicon. A fitting process was employed with various reference structures sampled by MD. Actively exploring and learning the wide-range of phase space enabled us to develop a robust interatomic potential. Our interatomic potential reproduced the bulk properties of Si and SiO2 polymorphs well, in addition to the radial distribution function and bond angle distribution of amorphous SiO2. The covalent-ionic mixed-bond nature of the interatomic potential well reproduced the dissociation process of an oxygen molecule on the Si/SiO2 interface. The initial oxidation simulation was performed on the silicon surface. We grew the amorphous SiO2 layer by incorporating the oxygen molecules into the silicon network at the interface. The density of the SiO2 layer and the charge distribution at the interface showed good agreement with the experimental data.

  8. The Adjuvant Effect of Ambient Particulate Matter Is Closely Reflected by the Particulate Oxidant Potential

    PubMed Central

    Li, Ning; Wang, Meiying; Bramble, Lori A.; Schmitz, Debra A.; Schauer, James J.; Sioutas, Constantinos; Harkema, Jack R.; Nel, Andre E.

    2009-01-01

    Background It has been demonstrated that ambient particulate matter (PM) can act as an adjuvant for allergic sensitization. Redox-active organic chemicals on the particle surface play an important role in PM adverse health effects and may determine the adjuvant effect of different particle types according to their potential to perturb redox equilibrium in the immune system. Objectives We determined whether the adjuvant effect of ambient fine particles versus ultrafine particles (UFPs) is correlated to their prooxidant potential. Methods We have established an intranasal sensitization model that uses ambient PM as a potential adjuvant for sensitization to ovalbumin (OVA), which enhances the capacity for secondary OVA challenge to induce allergic airway inflammation. Results UFPs with a greater polycyclic aromatic hydrocarbon (PAH) content and higher oxidant potential enhanced OVA sensitization more readily than did fine particles. This manifests as enhanced allergic inflammation upon secondary OVA challenge, leading to eosinophilic inflammation and mucoid hyperplasia starting at the nasal turbinates all the way down to the small pulmonary airways. The thiol antioxidant N-acetyl cysteine was able to suppress some of these sensitization events. Conclusions The adjuvant effects of ambient UFP is determined by their oxidant potential, which likely plays a role in changing the redox equilibrium in the mucosal immune system. PMID:19654922

  9. The adjuvant effect of ambient particulate matter is closely reflected by the particulate oxidant potential.

    PubMed

    Li, Ning; Wang, Meiying; Bramble, Lori A; Schmitz, Debra A; Schauer, James J; Sioutas, Constantinos; Harkema, Jack R; Nel, Andre E

    2009-07-01

    It has been demonstrated that ambient particulate matter (PM) can act as an adjuvant for allergic sensitization. Redox-active organic chemicals on the particle surface play an important role in PM adverse health effects and may determine the adjuvant effect of different particle types according to their potential to perturb redox equilibrium in the immune system. We determined whether the adjuvant effect of ambient fine particles versus ultrafine particles (UFPs) is correlated to their prooxidant potential. We have established an intranasal sensitization model that uses ambient PM as a potential adjuvant for sensitization to ovalbumin (OVA), which enhances the capacity for secondary OVA challenge to induce allergic airway inflammation. UFPs with a greater polycyclic aromatic hydrocarbon (PAH) content and higher oxidant potential enhanced OVA sensitization more readily than did fine particles. This manifests as enhanced allergic inflammation upon secondary OVA challenge, leading to eosinophilic inflammation and mucoid hyperplasia starting at the nasal turbinates all the way down to the small pulmonary airways. The thiol antioxidant N-acetyl cysteine was able to suppress some of these sensitization events. The adjuvant effects of ambient UFP is determined by their oxidant potential, which likely plays a role in changing the redox equilibrium in the mucosal immune system.

  10. Improving the oxidative stability of a high redox potential fungal peroxidase by rational design.

    PubMed

    Sáez-Jiménez, Verónica; Acebes, Sandra; Guallar, Victor; Martínez, Angel T; Ruiz-Dueñas, Francisco J

    2015-01-01

    Ligninolytic peroxidases are enzymes of biotechnological interest due to their ability to oxidize high redox potential aromatic compounds, including the recalcitrant lignin polymer. However, different obstacles prevent their use in industrial and environmental applications, including low stability towards their natural oxidizing-substrate H2O2. In this work, versatile peroxidase was taken as a model ligninolytic peroxidase, its oxidative inactivation by H2O2 was studied and different strategies were evaluated with the aim of improving H2O2 stability. Oxidation of the methionine residues was produced during enzyme inactivation by H2O2 excess. Substitution of these residues, located near the heme cofactor and the catalytic tryptophan, rendered a variant with a 7.8-fold decreased oxidative inactivation rate. A second strategy consisted in mutating two residues (Thr45 and Ile103) near the catalytic distal histidine with the aim of modifying the reactivity of the enzyme with H2O2. The T45A/I103T variant showed a 2.9-fold slower reaction rate with H2O2 and 2.8-fold enhanced oxidative stability. Finally, both strategies were combined in the T45A/I103T/M152F/M262F/M265L variant, whose stability in the presence of H2O2 was improved 11.7-fold. This variant showed an increased half-life, over 30 min compared with 3.4 min of the native enzyme, under an excess of 2000 equivalents of H2O2. Interestingly, the stability improvement achieved was related with slower formation, subsequent stabilization and slower bleaching of the enzyme Compound III, a peroxidase intermediate that is not part of the catalytic cycle and leads to the inactivation of the enzyme.

  11. Methylmercury oxidative degradation potentials in contaminated and pristine sediments of the Carson River, Nevada

    USGS Publications Warehouse

    Oremland, R.S.; Miller, L.G.; Dowdle, P.; Connell, T.; Barkay, T.

    1995-01-01

    Sediments from mercury-contaminated and uncontaminated reaches of the Carson River, Nevada, were assayed for sulfate reduction, methanogenesis, denitrification, and monomethylmercury (MeHg) degradation. Demethylation of [14C]MeHg was detected at all sites as indicated by the formation of 14CO2 and 14CH4. Oxidative demethylation was indicated by the formation of 14CO2 and was present at significant levels in all samples. Oxidized/reduced demethylation product ratios (i.e., 14CO2/14CH4 ratios) generally ranged from 4.0 in surface layers to as low as 0.5 at depth. Production of 14CO2 was most pronounced at sediment surfaces which were zones of active denitrification and sulfate reduction but was also significant within zones of methanogenesis. In a core taken from an uncontaminated site having a high proportion of oxidized, coarse-grain sediments, sulfate reduction and methanogenic activity levels were very low and 14CO2 accounted for 98% of the product formed from [14C]MeHg. There was no apparent relationship between the degree of mercury contamination of the sediments and the occurrence of oxidative demethylation. However, sediments from Fort Churchill, the most contaminated site, were most active in terms of demethylation potentials. Inhibition of sulfate reduction with molybdate resulted in significantly depressed oxidized/reduced demethylation product ratios, but overall demethylation rates of inhibited and uninhibited samples were comparable. Addition of sulfate to sediment slurries stimulated production of 14CO2 from [14C]MeHg, while 2-bromoethanesulfonic acid blocked production of 14CH4. These results reveal the importance of sulfate-reducing and methanogenic bacteria in oxidative demethylation of MeHg in anoxic environments.

  12. Oxidative stress and mitochondrial dysfunction in atherosclerosis: mitochondria-targeted antioxidants as potential therapy.

    PubMed

    Victor, V M; Apostolova, N; Herance, R; Hernandez-Mijares, A; Rocha, M

    2009-01-01

    Chronic and acute overproduction of reactive oxygen species (ROS) under pathophysiologic conditions forms an integral part of the development of cardiovascular diseases (CVD), and in particular atherosclerosis. These ROS are released from different sources, such as xanthine oxidase, lipoxygenase, nicotinamide adenine dinucleotide phosphate oxidase, the uncoupling of nitric oxide synthase and, in particular, mitochondria. Endothelial dysfunction, characterized by a loss of nitric oxide (NO) bioactivity, occurs early on in the development of atherosclerosis, and determines future vascular complications. Although the molecular mechanisms responsible for mitochondria-mediated disease processes are not clear, oxidative stress seems to play an important role. In general, ROS are essential to cell function, but adequate levels of antioxidant defenses are required in order to avoid the harmful effects of excessive ROS production. Mitochondrial oxidative stress damage and dysfunction contribute to a number of cell pathologies that manifest themselves through a range of conditions. This review considers the process of atherosclerosis from a mitochondrial perspective, and assesses strategies for the targeted delivery of antioxidants to mitochondria that are currently under development. We will provide a summary of the following areas: the cellular metabolism of reactive oxygen species (ROS) and its role in pathophysiological processes such as atherosclerosis; currently available antioxidants and possible reasons for their efficacy and inefficacy in ameliorating oxidative stress-mediated diseases; and recent developments in mitochondrially-targeted antioxidants that concentrate on the matrix-facing surface of the inner mitochondrial membrane in order to protect against mitochondrial oxidative damage, and their therapeutic potential as a treatment for atherosclerosis.

  13. Methylmercury Oxidative Degradation Potentials in Contaminated and Pristine Sediments of the Carson River, Nevada

    PubMed Central

    Oremland, R. S.; Miller, L. G.; Dowdle, P.; Connell, T.; Barkay, T.

    1995-01-01

    Sediments from mercury-contaminated and uncontaminated reaches of the Carson River, Nevada, were assayed for sulfate reduction, methanogenesis, denitrification, and monomethylmercury (MeHg) degradation. Demethylation of [(sup14)C]MeHg was detected at all sites as indicated by the formation of (sup14)CO(inf2) and (sup14)CH(inf4). Oxidative demethylation was indicated by the formation of (sup14)CO(inf2) and was present at significant levels in all samples. Oxidized/reduced demethylation product ratios (i.e., (sup14)CO(inf2)/(sup14)CH(inf4) ratios) generally ranged from 4.0 in surface layers to as low as 0.5 at depth. Production of (sup14)CO(inf2) was most pronounced at sediment surfaces which were zones of active denitrification and sulfate reduction but was also significant within zones of methanogenesis. In a core taken from an uncontaminated site having a high proportion of oxidized, coarse-grain sediments, sulfate reduction and methanogenic activity levels were very low and (sup14)CO(inf2) accounted for 98% of the product formed from [(sup14)C]MeHg. There was no apparent relationship between the degree of mercury contamination of the sediments and the occurrence of oxidative demethylation. However, sediments from Fort Churchill, the most contaminated site, were most active in terms of demethylation potentials. Inhibition of sulfate reduction with molybdate resulted in significantly depressed oxidized/reduced demethylation product ratios, but overall demethylation rates of inhibited and uninhibited samples were comparable. Addition of sulfate to sediment slurries stimulated production of (sup14)CO(inf2) from [(sup14)C]MeHg, while 2-bromoethanesulfonic acid blocked production of (sup14)CH(inf4). These results reveal the importance of sulfate-reducing and methanogenic bacteria in oxidative demethylation of MeHg in anoxic environments. PMID:16535081

  14. Oxidation-potential tuning of tungsten-alkylidyne complexes over a 2 V range.

    PubMed

    Haines, Daniel E; O'Hanlon, Daniel C; Manna, Joseph; Jones, Marya K; Shaner, Sarah E; Sun, Jibin; Hopkins, Michael D

    2013-08-19

    The electrochemistry and electronic structures of over 30 tungsten-alkylidyne compounds of the form W(CR)L(n)L'(4-n)X (R = H, Bu(t), Ph, p-C6H4CCH, p-C6H4CCSiPr(i)3; X = F, Cl, Br, I, OTf, Bu(n), CN, OSiMe3, OPh; L/L' = PMe3, 1/2 dmpe, 1/2 depe, 1/2 dppe, 1/2 tmeda, P(OMe)3, CO, CNBu(t), py), in which the alkylidyne R group and L and X ligands are systematically varied, have been investigated using cyclic voltammetry and density functional theory calculations in order to determine the extent to which the oxidation potential may be tuned and its dependence on the nature of the metal-ligand interactions. The first oxidation potentials are found to span a range of ∼2 V. Symmetry considerations and the electronic-structure calculations indicate that the highest occupied molecular orbital (and redox orbital) is of principal d(xy) orbital parentage for most of the compounds in this series. The dependence of the oxidation potential on ligand is a strong function of the symmetry relationship between the substituent and the d(xy) orbital, being much more sensitive to the nature of the equatorial L ligands (π symmetry, with respect to d(xy), ΔE1/2 ≅ 0.5 V/L) than to the axial CR and X ligands (nonbonding with respect to d(xy), ΔE(1/2) < 0.3 V/L). The oxidation potential is linearly correlated with the calculated d(xy) orbital energy (slope ≅ 1, R(2) = 0.97), which thus provides a convenient computational descriptor for the potential. The strength of the correlation and slope of unity are proposed to be manifestations of the small inner-sphere reorganization energy associated with one-electron oxidation.

  15. The effects of exercise load during development on oxidative stress levels and antioxidant potential in adulthood.

    PubMed

    Lee, S; Hashimoto, J; Suzuki, T; Satoh, A

    2017-02-01

    The objective of this study was to elucidate the impact of physical activity during the growth period as well as on oxidative stress and antioxidative potential in adulthood. The experimental animals used were four-week old male Wistar rats, which were randomly divided into three groups. The exercise loads were as follows: control (CON), treadmill exercise (TE), and jumping exercise (JE). The exercise was performed at the same time of day, at a frequency of five days per week, for eight weeks. Derivatives of reactive oxygen metabolites (d-ROSs) and biological antioxidant potential (BAP) were measured during periods of rest prior to commencement of the experiment and after the experiment. Analysis was conducted using a Wilcoxon signed-rank test and Schaffer's multiple comparison procedure and the significance level was set at p < 0.05. The percent increase in d-ROM levels in the JE group, which experienced short-duration intense exercise loads, was higher than that in the TE group, which experienced moderately intense exercise loads. However, BAP, which is an index of antioxidant potential, markedly decreased in adulthood in the CON group, as compared to that in the developmental period, whereas the exercise groups showed no notable changes in BAP levels. Oxidative stress levels and antioxidant potential are affected differently in adulthood, depending on the intensity of sustained exercise loads experienced during development. Results suggested that in order to increase antioxidant potential, while taking oxidative stress production into account, moderately intense exercise loads are more desirable than highly intense exercise loads.

  16. Insights into organic carbon oxidation potential during fluvial transport from controlled laboratory and natural field experiments

    NASA Astrophysics Data System (ADS)

    Scheingross, Joel S.; Dellinger, Mathieu; Golombek, Nina; Hilton, Robert G.; Hovius, Niels; Sachse, Dirk; Turowski, Jens M.; Vieth-Hillebrand, Andrea; Wittmann, Hella

    2017-04-01

    Over geologic timescales, the exchange of organic carbon (OC) between the atmosphere, biosphere and geosphere is thought to be a major control on atmospheric carbon dioxide (CO2) concentrations, and hence global climate. The carbon fluxes from the oxidation of rock-derived OC (a CO2 source) and erosion and transport of biospheric OC (a potential CO2 sink) during fluvial transit are approximately the same order of magnitude or larger than those from silicate weathering (France-Lanord and Derry, 1997; Bouchez et al., 2010). Despite field data showing oxidation of OC moving downstream in lowland rivers, it is unclear if losses occur primarily during active fluvial transport within the river, where OC is in continual motion within an aerated environment, or during longer periods when OC is temporarily stored in river floodplains which may be anoxic. This represents a major knowledge gap, as the unknown location of OC oxidation (i.e., river vs. floodplain) limits our ability to develop process-based models that can be employed to predict OC losses, constrain carbon budgets, and unravel links between climate, tectonics, and erosion. To fill this gap, we investigated the potential for OC oxidation in both controlled laboratory experiments and a simplified field setting. We consider both rock-derived and biospheric OC. Our experiments simulated fluvial transport without floodplain storage, allowing mixtures of OC-rich and siliciclastic sediment to be transported for distances of 1000 km in annular flumes while making time-series measurements of OC concentration in both the solid (POC) and dissolved (DOC) loads, as well as measurements of rhenium concentration, which serves as a proxy for the oxidation of rock-derived OC. These transport experiments were compared to static, control experiments where water and sediment in the same proportion were placed in still water. Initial results for transport of OC-rich soil show similar behavior between the transport and static

  17. Oxidative stress as a potential causal factor for autoimmune hemolytic anemia and systemic lupus erythematosus

    PubMed Central

    Fujii, Junichi; Kurahashi, Toshihiro; Konno, Tasuku; Homma, Takujiro; Iuchi, Yoshihito

    2015-01-01

    The kidneys and the blood system mutually exert influence in maintaining homeostasis in the body. Because the kidneys control erythropoiesis by producing erythropoietin and by supporting hematopoiesis, anemia is associated with kidney diseases. Anemia is the most prevalent genetic disorder, and it is caused by a deficiency of glucose 6-phosphate dehydrogenase (G6PD), for which sulfhydryl oxidation due to an insufficient supply of NADPH is a likely direct cause. Elevated reactive oxygen species (ROS) result in the sulfhydryl oxidation and hence are another potential cause for anemia. ROS are elevated in red blood cells (RBCs) under superoxide dismutase (SOD1) deficiency in C57BL/6 mice. SOD1 deficient mice exhibit characteristics similar to autoimmune hemolytic anemia (AIHA) and systemic lupus erythematosus (SLE) at the gerontic stage. An examination of AIHA-prone New Zealand Black (NZB) mice, which have normal SOD1 and G6PD genes, indicated that ROS levels in RBCs are originally high and further elevated during aging. Transgenic overexpression of human SOD1 in erythroid cells effectively suppresses ROS elevation and ameliorates AIHA symptoms such as elevated anti-RBC antibodies and premature death in NZB mice. These results support the hypothesis that names oxidative stress as a risk factor for AIHA and other autoimmune diseases such as SLE. Herein we discuss the association between oxidative stress and SLE pathogenesis based mainly on the genetic and phenotypic characteristics of NZB and New Zealand white mice and provide insight into the mechanism of SLE pathogenesis. PMID:25949934

  18. Nicotine alkaloids as antioxidant and potential protective agents against in vitro oxidative haemolysis.

    PubMed

    Malczewska-Jaskóła, Karolina; Jasiewicz, Beata; Mrówczyńska, Lucyna

    2016-01-05

    The capacity of eleven nicotine alkaloids to reduce oxidative stress was investigated. In order to provide a structure-activity relationships analysis, new nicotine derivatives with a substituent introduced into the pyrrolidine ring were synthesized and investigated together with nicotine and its known analogs. All newly synthesized compounds were characterized by (1)H, (13)C NMR and EI-MS technique. The antioxidant properties of nicotine, its known analogs and newly produced derivatives, were evaluated by various antioxidant assays such 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH(•)) scavenging, ferrous ions (Fe(2+)) chelating activity and total reducing ability determination by Fe(3+) → Fe(2+) transformation assay. The protective effects of all compounds tested against 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH) and tert-butyl hydroperoxide (t-BuOOH)-induced oxidative haemolysis and morphological injury of human erythrocytes, were estimated in vitro. The results showed that nicotine alkaloids exhibited various antiradical efficacy and antioxidant activity in a structure- and a dose-dependent manner. In addition, the capacity of nicotine alkaloids to protect erythrocytes from AAPH- and t-BuOOH-induced oxidative haemolysis, was dependent on its incubation time with cells. Our findings showed that chemical and biological investigations conducted simultaneously can provide comprehensive knowledge concerning the antioxidant potential of nicotine alkaloids. This knowledge can be helpful in better understanding the properties of nicotine alkaloids under oxidative stress conditions.

  19. Oxidative stress as a potential causal factor for autoimmune hemolytic anemia and systemic lupus erythematosus.

    PubMed

    Fujii, Junichi; Kurahashi, Toshihiro; Konno, Tasuku; Homma, Takujiro; Iuchi, Yoshihito

    2015-05-06

    The kidneys and the blood system mutually exert influence in maintaining homeostasis in the body. Because the kidneys control erythropoiesis by producing erythropoietin and by supporting hematopoiesis, anemia is associated with kidney diseases. Anemia is the most prevalent genetic disorder, and it is caused by a deficiency of glucose 6-phosphate dehydrogenase (G6PD), for which sulfhydryl oxidation due to an insufficient supply of NADPH is a likely direct cause. Elevated reactive oxygen species (ROS) result in the sulfhydryl oxidation and hence are another potential cause for anemia. ROS are elevated in red blood cells (RBCs) under superoxide dismutase (SOD1) deficiency in C57BL/6 mice. SOD1 deficient mice exhibit characteristics similar to autoimmune hemolytic anemia (AIHA) and systemic lupus erythematosus (SLE) at the gerontic stage. An examination of AIHA-prone New Zealand Black (NZB) mice, which have normal SOD1 and G6PD genes, indicated that ROS levels in RBCs are originally high and further elevated during aging. Transgenic overexpression of human SOD1 in erythroid cells effectively suppresses ROS elevation and ameliorates AIHA symptoms such as elevated anti-RBC antibodies and premature death in NZB mice. These results support the hypothesis that names oxidative stress as a risk factor for AIHA and other autoimmune diseases such as SLE. Herein we discuss the association between oxidative stress and SLE pathogenesis based mainly on the genetic and phenotypic characteristics of NZB and New Zealand white mice and provide insight into the mechanism of SLE pathogenesis.

  20. Potential role of oxidative protein modification in energy metabolism in exercise.

    PubMed

    Aoi, Wataru; Naito, Yuji; Yoshikawa, Toshikazu

    2014-01-01

    Exercise leads to the production of reactive oxygen species (ROS) via several sources in the skeletal muscle. In particular, the mitochondrial electron transport chain in the muscle cells produces ROS along with an elevation in the oxygen consumption during exercise. Such ROS generated during exercise can cause oxidative modification of proteins and affect their functionality. Many evidences have been suggested that some muscle proteins, i.e., myofiber proteins, metabolic signaling proteins, and sarcoplasmic reticulum proteins can be a targets modified by ROS generated due to exercise. We detected the modification of carnitine palmitoyltransferase I (CPT I) by Nε-(hexanoyl)lysine (HEL), one of the lipid peroxides, in exercised muscles, while the antioxidant astaxanthin reduced this oxidative stress-induced modification. Exercise-induced ROS may diminish CPT I activity caused by HEL modification, leading to a partly limited lipid utilization in the mitochondria. This oxidative protein modification may be useful as a potential biomarker to examine the oxidative stress levels, antioxidant compounds, and their possible benefits in exercise.

  1. Oxidation-Reduction Potential as a Biomarker for Severity and Acute Outcome in Traumatic Brain Injury

    PubMed Central

    Levy, Stewart; Carrick, Matthew; Mains, Charles W.; Slone, Denetta S.

    2016-01-01

    There are few reliable markers for assessing traumatic brain injury (TBI). Elevated levels of oxidative stress have been observed in TBI patients. We hypothesized that oxidation-reduction potential (ORP) could be a potent biomarker in TBI. Two types of ORP were measured in patient plasma samples: the static state of oxidative stress (sORP) and capacity for induced oxidative stress (icORP). Differences in ORP values as a function of time after injury, severity, and hospital discharge were compared using ANOVAs with significance at p ≤ 0.05. Logit regression analyses were used to predict acute outcome comparing ORP, Injury Severity Score (ISS), Abbreviated Injury Scale (AIS), and Glasgow Coma Scale (GCS). Antioxidant capacity (icORP) on day 4 was prognostic for acute outcomes (p < 0.05). An odds ratio of 4.08 was associated with poor acute outcome when icORP > 7.25 μC. IcORP was a better predictor than ISS, AIS, or GCS scores. sORP increased in those with the highest ISS values (p < 0.05). Based on these findings ORP is useful biomarker for severity and acute outcome in TBI patients. Changes in ORP values on day 4 after injury were the most prognostic, suggesting that patients' response to brain injury over time is a factor that determines outcome. PMID:27642494

  2. Potential oxidative stress in the bodies of electric arc welding operators: effect of photochemical smog.

    PubMed

    Zhu, You-Gen; Zhou, Jun-Fu; Shan, Wei-Ying; Zhou, Pei-Su; Tong, Gui-Zhong

    2004-12-01

    To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Seventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry. Compared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P < 0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P < 0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P < 0.05-0.005), the value of LPO in the WOs was increased gradually (P < 0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P < 0.005-0.001), but LPO increased (P < 0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients' alpha (6 items) was 0.8021, P < 0.0001, and that the standardized item alpha was 0.9577, P < 0.0001. Findings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.

  3. Arginine-Based Inhibitors of Nitric Oxide Synthase: Therapeutic Potential and Challenges

    PubMed Central

    Víteček, Jan; Lojek, Antonín; Valacchi, Giuseppe; Kubala, Lukáš

    2012-01-01

    In the past three decades, nitric oxide has been well established as an important bioactive molecule implicated in regulation of cardiovascular, nervous, and immune systems. Therefore, it is not surprising that much effort has been made to find specific inhibitors of nitric oxide synthases (NOS), the enzymes responsible for production of nitric oxide. Among the many NOS inhibitors developed to date, inhibitors based on derivatives and analogues of arginine are of special interest, as this category includes a relatively high number of compounds with good potential for experimental as well as clinical application. Though this group of inhibitors covers early nonspecific compounds, modern drug design strategies such as biochemical screening and computer-aided drug design have provided NOS-isoform-specific inhibitors. With an emphasis on major advances in this field, a comprehensive list of inhibitors based on their structural characteristics is discussed in this paper. We provide a summary of their biochemical properties as well as their observed effects both in vitro and in vivo. Furthermore, we focus in particular on their pharmacology and use in recent clinical studies. The potential of newly designed specific NOS inhibitors developed by means of modern drug development strategies is highlighted. PMID:22988346

  4. Chondroitin sulfate-capped super-paramagnetic iron oxide nanoparticles as potential carriers of doxorubicin hydrochloride.

    PubMed

    Mallick, Neha; Anwar, Mohammed; Asfer, Mohammed; Mehdi, Syed Hassan; Rizvi, Mohammed Moshahid Alam; Panda, Amulya Kumar; Talegaonkar, Sushama; Ahmad, Farhan Jalees

    2016-10-20

    Chondroitin-4-sulfate (CS), a glycosaminoglycan, was used to prepare CS-capped super-paramagnetic iron oxide nanoparticles, which were further employed for loading a water-soluble chemotherapeutic agent (doxorubicin hydrochloride, DOX). CS-capped SPIONs have potential biomedical application in cancer targeting. The optimized formulation had a hydrodynamic size of 91.2±0.8nm (PDI; 0.228±0.004) and zeta potential of -49.1±1.66mV. DOX was loaded onto the formulation up to 2% (w/w) by physical interaction with CS. TEM showed nano-sized particles having a core-shell structure. XRD confirmed crystal phase of iron oxide. FT-IR conceived the interaction of iron oxide with CS as bidentate chelation and also confirmed DOX loading. Vibration sample magnetometry confirmed super-paramagnetic nature of nanoparticles, with saturation magnetization of 0.238emug(-1). In vitro release profile at pH 7.4 showed that 96.67% of DOX was released within 24h (first order kinetics). MTT assay in MCF7 cells showed significantly higher (p<0.0001) cytotoxicity for DOX in SPIONs than DOX solution (IC50 values 6.294±0.4169 and 11.316±0.1102μgmL(-1), respectively).

  5. Adjuvant regional chemotherapy and systemic chemotherapy versus systemic chemotherapy alone in patients with stage II-III colorectal cancer: a multicentre randomised controlled phase III trial.

    PubMed

    Nordlinger, Bernard; Rougier, Philippe; Arnaud, Jean-Pierre; Debois, Muriel; Wils, Jaques; Ollier, Jean-Claude; Grobost, Olivier; Lasser, Philippe; Wals, Jacob; Lacourt, Jerome; Seitz, Jean-François; Guimares dos Santos, Jose; Bleiberg, Harry; Mackiewickz, Rémy; Conroy, Thierry; Bouché, Olivier; Morin, Thierry; Baila, Liliana; van Cutsem, Eric; Bedenne, Laurent

    2005-07-01

    Systemic adjuvant chemotherapy can improve overall survival and reduce the incidence of distant metastases for patients with advanced colon cancer. This study aimed to investigate whether regional chemotherapy (given by intraperitoneal or intraportal methods) combined with systemic chemotherapy was more effective than was systemic chemotherapy alone in terms of survival and recurrence for patients with stage II-III colorectal cancer. The study also compared systemic chemotherapy with fluorouracil and folinic acid with that of fluorouracil and levamisole. During surgery, 753 patients with stage II-III colorectal cancer were randomly assigned to systemic chemotherapy alone (379 with fluorouracil and folinic acid, and 374 with fluorouracil and levamisole), and 748 to postoperative regional chemotherapy with fluorouracil followed by systemic chemotherapy with fluorouracil and folinic acid (n=368) or with fluorouracil and levamisole (n=380). Regional chemotherapy was given intraperitoneally (n=415) or intraportally (n=235) according to institution. The primary endpoint was 5-year overall survival. Secondary endpoints were 5-year disease-free survival and toxic effects. Analyses were by intention to treat. Median follow-up was 6.8 years (range 0.0-10.1). 5-year overall survival was 72.3% (95% CI 69.0-75.6) for patients assigned regional and systemic chemotherapy, compared with 72.0% (68.7-75.3) for those assigned systemic chemotherapy alone (hazard ratio [HR] 0.97 [0.81-1.15], p=0.69). 5-year overall survival for all patients assigned fluorouracil and levamisole was 72.0% (68.7-75.2) compared with 72.3% (69.0-75.6) for all those assigned fluorouracil and folinic acid (HR 0.98 [0.82-1.17], p=0.81). The hazard ratios for 5-year disease-free survival were 0.94 (0.80-1.10) for regional versus non-regional treatment, and 0.92 (0.79-1.08) for all fluorouracil and levamisole versus fluorouracil and folinic acid. Grade 3-4 toxic effects were low in all groups. Fluorouracil

  6. Anaerobic methane oxidation coupled to nitrite reduction can be a potential methane sink in coastal environments.

    PubMed

    Shen, Li-Dong; Hu, Bao-Lan; Liu, Shuai; Chai, Xiao-Ping; He, Zhan-Fei; Ren, Hong-Xing; Liu, Yan; Geng, Sha; Wang, Wei; Tang, Jing-Liang; Wang, Yi-Ming; Lou, Li-Ping; Xu, Xiang-Yang; Zheng, Ping

    2016-08-01

    In the current study, we investigated nitrite-dependent anaerobic methane oxidation (N-DAMO) as a potential methane sink in the Hangzhou Bay and the adjacent Zhoushan sea area. The potential activity of the N-DAMO process was primarily observed in Hangzhou Bay by means of (13)C-labeling experiments, whereas very low or no potential N-DAMO activity could be detected in the Zhoushan sea area. The measured potential N-DAMO rates ranged from 0.2 to 1.3 nmol (13)CO2 g(-1) (dry sediment) day(-1), and the N-DAMO potentially contributed 2.0-9.4 % to the total microbial methane oxidation in the examined sediments. This indicated that the N-DAMO process may be an alternative pathway in the coastal methane cycle. Phylogenetic analyses confirmed the presence of Candidatus Methylomirabilis oxyfera-like bacteria in all the examined sediments, while the group A members (the dominant bacteria responsible for N-DAMO) were found mainly in Hangzhou Bay. Quantitative PCR showed that the 16S rRNA gene abundance of Candidatus M. oxyfera-like bacteria varied from 5.4 × 10(6) to 5.0 × 10(7) copies g(-1) (dry sediment), with a higher abundance observed in Hangzhou Bay. In addition, the overlying water NO3 (-) concentration and salinity were identified as the most important factors influencing the abundance and potential activity of Candidatus M. oxyfera-like bacteria in the examined sediments. This study showed the evidence of N-DAMO in coastal environments and indicated the importance of N-DAMO as a potential methane sink in coastal environments.

  7. Ionization potentials of transparent conductive indium tin oxide films covered with a single layer of fluorine-doped tin oxide nanoparticles grown by spray pyrolysis deposition

    SciTech Connect

    Fukano, Tatsuo; Motohiro, Tomoyoshi; Ida, Takashi; Hashizume, Hiroo

    2005-04-15

    Indium tin oxide (ITO) films deposited with single layers of monodispersive fluorine-doped tin oxide (FTO) nanoparticles of several nanometers in size were grown on glass substrates by intermittent spray pyrolysis deposition using conventional atomizers. These films have significantly higher ionization potentials than the bare ITO and FTO films grown using the same technique. The ITO films covered with FTO particles of 7 nm in average size show an ionization potential of 5.01 eV, as compared with {approx}4.76 and {approx}4.64 eV in ITO and FTO films, respectively, which decreases as the FTO particle size increases. The ionization potentials are practically invariant against oxidation and reduction treatments, promising a wide application of the films to transparent conducting oxide electrodes in organic electroluminescent devices and light-emitting devices of high efficiencies.

  8. Axially-modified paddlewheel diruthenium(II,III)-ibuprofenato metallodrugs and the influence of the structural modification on U87MG and A172 human glioma cell proliferation, apoptosis, mitosis and migration.

    PubMed

    Hanif-Ur-Rehman; Freitas, Tatiana E; Gomes, Renata N; Colquhoun, Alison; de Oliveira Silva, Denise

    2016-12-01

    The metallodrug chloridotetrakis(ibuprofenato)diruthenium(II,III) ([Ru2(Ibp)4Cl] or RuIbpCl (1), Ibp=carboxylate anion derived from the non-steroidal anti-inflammatory drug ibuprofen) has shown promising results in vitro and in vivo, which point to its potential as an inhibitor of glioma tumour growth in vivo. In order to get insight into the influence of structural changes on the biological response of the metallodrug, the [Ru2(Ibp)4] metal-metal multiply bonded paddlewheel unit was modified for the axial ligand. Two new analogues, [Ru2(Ibp)4(CF3SO3)] (2) and [Ru2(Ibp)4(EtOH)2]PF6 (3), were synthesized and fully characterized by elemental analysis, ESI-MS, vibrational (FTIR, Raman) and electronic (UV/VIS/NIR) spectroscopy, magnetic susceptibility, molar conductivity measurements, and thermal analysis. RuIbpCl was re-prepared and complementary characterization to previous work was performed. The three axially-modified RuIbp metallodrugs were compared for their effects on U87MG and A172 human glioma cell proliferation, apoptosis, mitosis, and cell migration in vitro. The results provide evidence that the chloride ligand in RuIbpCl may play key role in the mode of action of the metallodrug, since the best results for antiproliferative activity were found for (1) in both types of human glioma cells. All the metallodrugs, (1), (2) and (3), were uptaken by the cells, and were shown to cause increase on number of apoptotic cells and decrease on number of mitotic cells. Additionally, the RuIbp metallodrugs were capable of inhibiting cell migration process in both human glioma cell lines. These data are extremely promising as drugs which can inhibit both cell proliferation/mitosis and inhibit cell migration could target two major chemotherapeutic targets in high grade gliomas. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Rivaroxaban in antiphospholipid syndrome (RAPS) protocol: a prospective, randomized controlled phase II/III clinical trial of rivaroxaban versus warfarin in patients with thrombotic antiphospholipid syndrome, with or without SLE.

    PubMed

    Cohen, H; Doré, C J; Clawson, S; Hunt, B J; Isenberg, D; Khamashta, M; Muirhead, N

    2015-09-01

    The current mainstay of the treatment of thrombotic antiphospholipid syndrome (APS) is long-term anticoagulation with vitamin K antagonists (VKAs) such as warfarin. Non-VKA oral anticoagulants (NOACs), which include rivaroxaban, have been shown to be effective and safe compared with warfarin for the treatment of venous thromboembolism (VTE) in major phase III prospective, randomized controlled trials (RCTs), but the results may not be directly generalizable to patients with APS. The primary aim is to demonstrate, in patients with APS and previous VTE, with or without systemic lupus erythematosus (SLE), that the intensity of anticoagulation achieved with rivaroxaban is not inferior to that of warfarin. Secondary aims are to compare rates of recurrent thrombosis, bleeding and the quality of life in patients on rivaroxaban with those on warfarin. Rivaroxaban in antiphospholipid syndrome (RAPS) is a phase II/III prospective non-inferiority RCT in which eligible patients with APS, with or without SLE, who are on warfarin, target international normalized ratio (INR) 2.5 for previous VTE, will be randomized either to continue warfarin (standard of care) or to switch to rivaroxaban. Intensity of anticoagulation will be assessed using thrombin generation (TG) testing, with the primary outcome the percentage change in endogenous thrombin potential (ETP) from randomization to day 42. Other TG parameters, markers of in vivo coagulation activation, prothrombin fragment 1.2, thrombin antithrombin complex and D-dimer, will also be assessed. If RAPS demonstrates i) that the anticoagulant effect of rivaroxaban is not inferior to that of warfarin and ii) the absence of any adverse effects that cause concern with regard to the use of rivaroxaban, this would provide sufficient supporting evidence to make rivaroxaban a standard of care for the treatment of APS patients with previous VTE, requiring a target INR of 2.5. © The Author(s) 2015.

  10. Safety of zoledronic acid and incidence of osteonecrosis of the jaw (ONJ) during adjuvant therapy in a randomised phase III trial (AZURE: BIG 01-04) for women with stage II/III breast cancer.

    PubMed

    Coleman, R; Woodward, E; Brown, J; Cameron, D; Bell, R; Dodwell, D; Keane, M; Gil, M; Davies, C; Burkinshaw, R; Houston, S J; Grieve, R J; Barrett-Lee, P J; Thorpe, H

    2011-06-01

    The AZURE trial is an ongoing phase III, academic, multi-centre, randomised trial designed to evaluate the role of zoledronic acid (ZOL) in the adjuvant therapy of women with stage II/III breast cancer. Here, we report the safety and tolerability profile of ZOL in this setting. Eligible patients received (neo)adjuvant chemotherapy and/or endocrine therapy and were randomised to receive neither additional treatment nor intravenous ZOL 4 mg. ZOL was administered after each chemotherapy cycle to exploit potential sequence-dependent synergy. ZOL was continued for 60 months post-randomisation (six doses in the first 6 months, eight doses in the following 24 months and five doses in the final 30 months). Serious (SAE) and non-serious adverse event (AE) data generated during the first 36 months on study were analysed for the safety population. 3,360 patients were recruited to the AZURE trial. The safety population comprised 3,340 patients (ZOL 1,665; control 1,675). The addition of ZOL to standard treatment did not significantly impact on chemotherapy delivery. SAE were similar in both treatment arms. No significant safety differences were seen apart from the occurrence of osteonecrosis of the jaw (ONJ) in the ZOL group (11 confirmed cases; 0.7%; 95% confidence interval 0.3-1.1%). ZOL in the adjuvant setting is well tolerated, and can be safely administered in addition to adjuvant therapy including chemotherapy. The adverse events were consistent with the known safety profile of ZOL, with a low incidence of ONJ.

  11. Physeal fractures of the distal tibia and fibula (Salter-Harris Type I, II, III, and IV fractures).

    PubMed

    Podeszwa, David A; Mubarak, Scott J

    2012-06-01

    Physeal fractures of the distal tibia and fibula are common and can be seen at any age, although most are seen in the adolescent. An understanding of the unique anatomy of the skeletally immature ankle in relation to the mechanism of injury will help one understand the injury patterns seen in this population. A thorough clinical exam is critical to the diagnosis and treatment of these injuries and the avoidance of potentially catastrophic complications. Nondisplaced physeal fractures of the distal tibia and fibula can be safely treated nonoperatively. Displaced fractures should undergo a gentle reduction with appropriate anesthesia while multiple reduction attempts should be avoided. Gapping of the physis >3 mm after reduction should raise the suspicion of entrapped periosteum that will increase the risk of premature physeal closure. Open reduction of displaced Salter-Harris type III and IV fractures is critical to maintain joint congruity and minimize the risk of physeal arrest.

  12. Reduced Graphene Oxide Anodes for Potential Application in Algae Biophotovoltaic Platforms

    PubMed Central

    Ng, Fong-Lee; Jaafar, Muhammad Musoddiq; Phang, Siew-Moi; Chan, Zhijian; Salleh, Nurul Anati; Azmi, Siti Zulfikriyah; Yunus, Kamran; Fisher, Adrian C.; Periasamy, Vengadesh

    2014-01-01

    The search for renewable energy sources has become challenging in the current era, as conventional fuel sources are of finite origins. Recent research interest has focused on various biophotovoltaic (BPV) platforms utilizing algae, which are then used to harvest solar energy and generate electrical power. The majority of BPV platforms incorporate indium tin oxide (ITO) anodes for the purpose of charge transfer due to its inherent optical and electrical properties. However, other materials such as reduced graphene oxide (RGO) could provide higher efficiency due to their intrinsic electrical properties and biological compatibility. In this work, the performance of algae biofilms grown on RGO and ITO anodes were measured and discussed. Results indicate improved peak power of 0.1481 mWm−2 using the RGO electrode and an increase in efficiency of 119%, illustrating the potential of RGO as an anode material for applications in biofilm derived devices and systems. PMID:25531093

  13. Oxidative Stress and Carcinogenesis: Potential of Phytochemicals in Breast Cancer Therapy.

    PubMed

    Forcados, Gilead Ebiegberi; James, Dorcas Bolanle; Sallau, Abdullahi Balarabe; Muhammad, Aliyu; Mabeta, Peace

    2017-04-01

    Breast cancer remains a burden in both developed and developing countries, with higher mortality in developing countries. Attempts to eradicate cancer have not been successful despite the progress made in the development of more novel chemotherapeutic drugs. Reactive-oxygen-species-mediated oxidative stress is known to play a role in breast cancer pathogenesis via genetic and epigenetic modifications, resulting in uncontrolled cell proliferation. Phytochemicals could provide leads for the development of alternative therapeutic agents due to their antioxidant activity, as well as their ability to induce apoptosis in cancer cells. However, most of the studies carried out using in vitro models do not continue with further studies in estrogen-receptor-positive in vivo breast cancer models, or fail to examine the possible biochemical mechanisms of phytochemical-based amelioration. This review examines oxidative-stress-mediated carcinogenesis and the potential of phytochemicals as anticancer agents.

  14. Oxidative stress and Alzheimer's disease: dietary polyphenols as potential therapeutic agents.

    PubMed

    Darvesh, Altaf S; Carroll, Richard T; Bishayee, Anupam; Geldenhuys, Werner J; Van der Schyf, Cornelis J

    2010-05-01

    Oxidative stress has been strongly implicated in the pathophysiology of neurodegenerative disorders such as Alzheimer's disease (AD). In recent years, antioxidants - especially those of dietary origin - have been suggested as possible agents useful for the prevention and treatment of AD. This article reviews the role of oxidative stress and the contribution of free radicals in the development of AD, and also discusses the use of antioxidants as a therapeutic strategy in the amelioration of this illness. The antioxidant potential of polyphenolic compounds obtained from dietary sources, such as anthocyanins from berries, catechins and theaflavins from tea, curcumin from turmeric, resveratrol from grapes and peanuts, the dihydrochalcones aspalathin and nothofagin from rooibos and the xanthone mangiferin from honeybush, are discussed in this review. The neuroprotective effects of these phytochemicals in preclinical models of AD are highlighted. Finally, innovative concepts, novel hypotheses, current challenges and future directions in the use of dietary polyphenols for the treatment of AD are discussed.

  15. Clinical potential of nitric oxide-independent soluble guanylate cyclase activators.

    PubMed

    Doggrell, Sheila A

    2005-09-01

    A major problem with using nitrates in the treatment of ischemic heart disease is that tolerance develops to their vasodilatory actions. YC-1 was used as the lead compound to synthesize further nitric oxide-independent soluble guanylate cyclase activators, including BAY-41-2272 and BAY-41-8543. A nitric oxide and heme-independent activator of soluble guanylate cyclase, BAY-58-2667, was subsequently discovered by high-throughput screening. Tolerance to the vasodilatory actions of BAY-41-8543 and BAY-58-2667 does not develop. Results from animal studies have suggested that these compounds may have potential in the treatment of ischemic heart disease, essential and pulmonary hypertension, congestive heart failure, glomerulonephritis and erectile dysfunction.

  16. Reduced graphene oxide anodes for potential application in algae biophotovoltaic platforms.

    PubMed

    Ng, Fong-Lee; Jaafar, Muhammad Musoddiq; Phang, Siew-Moi; Chan, Zhijian; Salleh, Nurul Anati; Azmi, Siti Zulfikriyah; Yunus, Kamran; Fisher, Adrian C; Periasamy, Vengadesh

    2014-12-22

    The search for renewable energy sources has become challenging in the current era, as conventional fuel sources are of finite origins. Recent research interest has focused on various biophotovoltaic (BPV) platforms utilizing algae, which are then used to harvest solar energy and generate electrical power. The majority of BPV platforms incorporate indium tin oxide (ITO) anodes for the purpose of charge transfer due to its inherent optical and electrical properties. However, other materials such as reduced graphene oxide (RGO) could provide higher efficiency due to their intrinsic electrical properties and biological compatibility. In this work, the performance of algae biofilms grown on RGO and ITO anodes were measured and discussed. Results indicate improved peak power of 0.1481 mWm(-2) using the RGO electrode and an increase in efficiency of 119%, illustrating the potential of RGO as an anode material for applications in biofilm derived devices and systems.

  17. Cholesterol potentiates beta-amyloid-induced toxicity in human neuroblastoma cells: involvement of oxidative stress.

    PubMed

    Ferrera, Patricia; Mercado-Gómez, Octavio; Silva-Aguilar, Martín; Valverde, Mahara; Arias, Clorinda

    2008-08-01

    Alterations in brain cholesterol concentration and metabolism seem to be involved in Alzheimer's disease (AD). In fact, several experimental studies have reported that modification of cholesterol content can influence the expression of the amyloid precursor protein (APP) and amyloid beta peptide (Abeta) production. However, it remains to be determined if changes in neuronal cholesterol content may influence the toxicity of Abeta peptides and the mechanism involved. Aged mice, AD patients and neurons exposed to Abeta, show a significant increase in membrane-associated oxidative stress. Since Abeta is able to promote oxidative stress directly by catalytically producing H(2)O(2) from cholesterol, the present work analyzed the effect of high cholesterol incorporated into human neuroblastoma cells in Abeta-mediated neurotoxicity and the role of reactive oxygen species (ROS) generation. Neuronal viability was studied also in the presence of 24S-hydroxycholesterol, the main cholesterol metabolite in brain, as well as the potential protective role of the lipophilic statin, lovastatin.

  18. Reduced Graphene Oxide Anodes for Potential Application in Algae Biophotovoltaic Platforms

    NASA Astrophysics Data System (ADS)

    Ng, Fong-Lee; Jaafar, Muhammad Musoddiq; Phang, Siew-Moi; Chan, Zhijian; Salleh, Nurul Anati; Azmi, Siti Zulfikriyah; Yunus, Kamran; Fisher, Adrian C.; Periasamy, Vengadesh

    2014-12-01

    The search for renewable energy sources has become challenging in the current era, as conventional fuel sources are of finite origins. Recent research interest has focused on various biophotovoltaic (BPV) platforms utilizing algae, which are then used to harvest solar energy and generate electrical power. The majority of BPV platforms incorporate indium tin oxide (ITO) anodes for the purpose of charge transfer due to its inherent optical and electrical properties. However, other materials such as reduced graphene oxide (RGO) could provide higher efficiency due to their intrinsic electrical properties and biological compatibility. In this work, the performance of algae biofilms grown on RGO and ITO anodes were measured and discussed. Results indicate improved peak power of 0.1481 mWm-2 using the RGO electrode and an increase in efficiency of 119%, illustrating the potential of RGO as an anode material for applications in biofilm derived devices and systems.

  19. Effect of Solanum surattense seed on the oxidative potential of cauda epididymal spermatozoa

    PubMed Central

    Thirumalai, T; David, E; Viviyan, Therasa S; Elumalai, EK

    2012-01-01

    Objective To evaluate the effect of aqueous seed extract of Solanum surattense (S. surattense) on the oxidative potential of cauda epididymal spermatozoa. Methods S. surattense seed extract was orally administered at the dosage of 10 mg/kg b.w. for 15 days, after which aspartate transferase (AST), alanine transferase (ALT), glutamate dehydrogenase (GDH), citric acid and iso-citrate dehydrogenase (ICDH) were assayed. Results The activity levels of the enzymes AST and ALT, which are considered to be the androgenicity in the sperm suspension, were depleted in the extract fed rats. The activity level of the enzyme ICDH, was reduced significantly in the treated group (P<0.001). Conclusions It can be concluded that the oral administration of the aqueous seed extract of S. surattense can deplete the oxidative stress of cauda epididymal spermatozoa in albino rats. PMID:23569828

  20. Nitric oxide synthase inhibitor aminoguanidine potentiates iminodipropionitrile-induced neurotoxicity in rats.

    PubMed

    Tariq, M; Khan, H A; Al Deeb, S; Al Moutaery, K

    1999-11-26

    This investigation was undertaken to study the effect of nitric oxide synthase inhibitor, aminoguanidine on iminodipropionitrile (IDPN)-induced neurobehavioral and vestibular toxicity in rats. The dyskinetic syndrome was produced in male Wistar rats by i.p. injections of IDPN (100 mg/kg) for 6 days. Aminoguanidine was administered orally in the doses of 50, 150 and 300 mg/kg, 60 min before IDPN in three different groups. Control rats received vehicle only, whereas another group was treated with 300 mg/kg of aminoguanidine alone (without IDPN). Our results showed that aminoguanidine significantly and dose dependently exacerbated the incidence and intensity of IDPN-induced dyskinetic head movements. Aminoguanidine potentiated IDPN-induced loss of air righting reflex. The histopathological examination of inner ear showed aggravation of IDPN-induced degeneration of sensory hair cells in the crista ampullaris by aminoguanidine. These results suggest the role of nitric oxide in IDPN-induced neurobehavioral and vestibular toxicity.

  1. Cumene hydroperoxide induced changes in oxidation-reduction potential in fresh and frozen seminal ejaculates.

    PubMed

    Agarwal, A; Sharma, R; Henkel, R; Roychoudhury, S; Sikka, S C; du Plessis, S; Sarda, Y B; Speyer, C; Nouh, M; Douglas, C; Kayali, Z; Ahmed, E S; Sabanegh, E

    2017-03-15

    Oxidation-reduction potential (ORP) is a newer integrated measure of the balance between total oxidants (reactive oxygen species-ROS) and reductants (antioxidants) that reflects oxidative stress in a biological system. This study measures ORP and evaluates the effect of exogenous induction of oxidative stress by cumene hydroperoxide (CH) on ORP in fresh and frozen semen using the MiOXSYS Analyzer. Semen samples from healthy donors (n = 20) were collected and evaluated for sperm parameters. All samples were then flash-frozen at -80°C. Oxidative stress was induced by CH (5 and 50 μmoles/ml). Static ORP (sORP-(mV/10(6) sperm/ml) and capacity ORP (cORP-μC/10(6) sperm/ml) were measured in all samples before and after freezing. All values are reported as mean ± SEM. Both 5 and 50 μmoles/ml of CH resulted in a significant decline in per cent motility compared to control in pre-freeze semen samples. The increase in both pre-freeze and post-thaw semen samples for sORP was higher in the controls than with 50 μmoles/ml of CH. The change from pre-freeze to post-thaw cORP was comparable. The system is a simple, sensitive and portable tool to measure the seminal ORP and its dynamic impact on sperm parameters in both fresh and frozen semen specimens.

  2. The Dynamic Interfacial Oxygen Potential Between Iron-Carbon Droplets and Oxidizing Slag

    NASA Astrophysics Data System (ADS)

    Gu, Kezhuan; Dogan, Neslihan; Coley, Kenneth S.

    2017-10-01

    The dynamic nature of the interfacial oxygen potential during dephosphorization was investigated based on the concept that P_{{{O}2 }} at the interface between slag and liquid metal is determined by the balance between oxygen supply from reducible oxides in the slag and oxygen consumption by alloying elements in the metal. Combining this approach with the knowledge that at the phosphorus reversion point the interfacial oxygen potential can be determined from the bulk phosphorus partition ratio, the mass transfer coefficient for FeO, k FeO, was determined for different slags and found to increase with increasing FeO content. In foamy slags, k FeO was found to be a linear function of slag liquid fraction. Equating the mass transfer rate of FeO in the slag with decarburization rate, the dynamic interfacial oxygen potential was calculated over the course of the reaction, and its effect on the rate determining step for dephosphorization was evaluated.

  3. Oxidative dissolution potential of biogenic and abiogenic TcO 2 in subsurface sediments

    NASA Astrophysics Data System (ADS)

    Fredrickson, James K.; Zachara, John M.; Plymale, Andrew E.; Heald, Steve M.; McKinley, James P.; Kennedy, David W.; Liu, Chongxuan; Nachimuthu, Ponnusamy

    2009-04-01

    Technetium-99 (Tc) is an important fission product contaminant associated with sites of nuclear fuels reprocessing and geologic nuclear waste disposal. Tc is highly mobile in its most oxidized state [Tc(VII)O4-] and less mobile in the reduced form [Tc(IV)O 2· nH 2O]. Here we investigate the potential for oxidation of Tc(IV) that was heterogeneously reduced by reaction with biogenic Fe(II) in two sediments differing in mineralogy and aggregation state; unconsolidated Pliocene-age fluvial sediment from the upper Ringold (RG) Formation at the Hanford Site and a clay-rich saprolite from the Field Research Center (FRC) background site on the Oak Ridge Site. Both sediments contained Fe(III) and Mn(III/IV) as redox active phases, but FRC also contained mass-dominant Fe-phyllosilicates of different types. Shewanella putrefaciens CN32 reduced Mn(III/IV) oxides and generated Fe(II) that was reactive with Tc(VII) in heat-killed, bioreduced sediment. After bioreduction and heat-killing, biogenic Fe(II) in the FRC exceeded that in RG by a factor of two. More rapid reduction rates were observed in the RG that had lower biogenic Fe(II), and less particle aggregation. EXAFS measurements indicated that the primary reduction product was a TcO 2-like phase in both sediments. The biogenic redox product Tc(IV) oxidized rapidly and completely in RG when contacted with air. Oxidation, in contrast, was slow and incomplete in the FRC, in spite of similar molecular scale speciation of Tc compared to RG. X-ray microprobe, electron microprobe, X-ray absorption spectroscopy, and micro X-ray diffraction were applied to the whole sediment and isolated Tc-containing particles. These analyses revealed that non-oxidizable Tc(IV) in the FRC existed as complexes with octahedral Fe(III) within intra-grain domains of 50-100 μm-sized, Fe-containing micas presumptively identified as celadonite. The markedly slower oxidation rates in FRC as compared to RG were attributed to mass

  4. Multiparametric MRI-based differentiation of WHO grade II/III glioma and WHO grade IV glioblastoma

    PubMed Central

    Wiestler, Benedikt; Kluge, Anne; Lukas, Mathias; Gempt, Jens; Ringel, Florian; Schlegel, Jürgen; Meyer, Bernhard; Zimmer, Claus; Förster, Stefan; Pyka, Thomas; Preibisch, Christine

    2016-01-01

    Non-invasive, imaging-based examination of glioma biology has received increasing attention in the past couple of years. To this end, the development and refinement of novel MRI techniques, reflecting underlying oncogenic processes such as hypoxia or angiogenesis, has greatly benefitted this research area. We have recently established a novel BOLD (blood oxygenation level dependent) based MRI method for the measurement of relative oxygen extraction fraction (rOEF) in glioma patients. In a set of 37 patients with newly diagnosed glioma, we assessed the performance of a machine learning model based on multiple MRI modalities including rOEF and perfusion imaging to predict WHO grade. An oblique random forest machine learning classifier using the entire feature vector as input yielded a five-fold cross-validated area under the curve of 0.944, with 34/37 patients correctly classified (accuracy 91.8%). The most important features in this classifier as per bootstrapped feature importance scores consisted of standard deviation of T1-weighted contrast enhanced signal, maximum rOEF value and cerebral blood volume (CBV) standard deviation. This study suggests that multimodal MRI information reflects underlying tumor biology, which is non-invasively detectable through integrative data analysis, and thus highlights the potential of such integrative approaches in the field of radiogenomics. PMID:27739434

  5. Influence of chloride in mortar made of Portland cement types II, III, and V on the near-field microwave reflection properties

    NASA Astrophysics Data System (ADS)

    Hu, Cairong; Benally, Aaron D.; Case, Tobias; Zoughi, Reza; Kurtis, Kimberly

    2000-07-01

    Corrosion of steel rebar in reinforced concrete structures, can be induced by the presence of chloride in the structure. Corrosion of steel rebar is a problematic issue in the construction industry as it compromises the strength and integrity of the structure. Although techniques exist for chloride detection and its migration into a structure, they are destructive, time consuming and cannot be used for the interrogation of large surfaces. In this investigation three different portland cement types; namely, ASTM types II, III and V were used, and six cubic (8' X 8' X 8') mortar specimens were produced all with water-to-cement (w/c) ratio of 0.6 and sand-to-cement (s/c) ratio of 1.5. Tap water was used when producing three of these specimens (one of each cement type). For the other three specimens calcium chloride was added to the mixing tap water resulting in a salinity of 2.5%. These specimens were placed in a hydration room for one day and thereafter left it the room temperature with low humidity. The reflection properties of these specimens, using an open-ended rectangular waveguide probe, were monitored daily at 3 GHz (S-band) and 10 GHz (X-band). The results show the influence of cement type on the reflection coefficient as well as the influence of chloride on the curing process and setting time.

  6. Histological structure and distribution of carbonic anhydrase isozymes (CA-I, II, III and VI) in major salivary glands in koalas.

    PubMed

    Mizuno, T; McKinnon, A; Ichihara, N; Amasaki, T; Asari, M; Nishita, T; Oishi, M; Soeta, S; Amasaki, H

    2009-11-01

    While the mandibular glands usually consist of only mucous acinar cells or a combination of mucous and serous cells in other species of mammals, those of koalas were serous glands. Rabbit mono-specific polyclonal anti-canine CA-I, II, III or VI antiserum showed cross-reactivity against corresponding koala carbonic anhydrase (CA) isozymes. Although immunohistochemical reactions to CA-I, II and VI in ductal cells were moderate to strong in the tested salivary glands, no reaction or only slight reactions were observed against CA-III. In the sublingual glands, moderate immunohistochemical reactions to CA-I, II and VI were also evident in serous acinar cells and serous demilunes. However, no reactions to the tested isozymes were observed in mucous acinar cells in these glands. With the exception of the histological structure of the mandibular glands, histological features and the distributional profile of CA isozymes of the salivary glands in koalas are relatively close to results obtained from horses.

  7. Beating the Odds: Successful Establishment of a Phase II/III Clinical Research Trial in Resource-Poor Liberia during the Largest-Ever Ebola Outbreak

    PubMed Central

    Doe-Anderson, J; Baseler, B; Driscoll, P; Johnson, M; Lysander, J; McNay, L; Njoh, WS; Smolskis, M; Wehrlen, L; Zuckerman, J

    2016-01-01

    It has been argued that a country such as Liberia, not fully recovered from the devastation of decades of civil unrest, lacked the appropriate ethical and regulatory framework, basic human and health care services, and infrastructure to carry out clinical trials according to international standards of quality during a public health emergency. However, as Liberia, Sierra Leone, and Guinea were being ravaged by the largest and most devastating Ebola Virus Disease (EVD) outbreak ever recorded, the topic of conducting clinical trials of experimental vaccine and treatment candidates in these resource-poor countries generated the keen interest and concern of scientists, researchers, physicians, bioethicists, philanthropists, and even politicians. Decisive action on behalf of the Liberian government, and a timely positive and supportive response from the United States (U.S.) government, led to the formation of PREVAIL (Partnership for Research on Ebola Vaccines in Liberia) – a clinical research partnership between the two governments. Within a span of 12 weeks, this partnership accomplished the unimaginable: the successful initiation of a Phase II/III vaccine clinical trial for EVD in Liberia. This paper will discuss the dynamics of the research collaboration, barriers encountered, breakthroughs realized, key elements of success, and lessons learned in the process. PMID:28042619

  8. Functional outcome after Mason II-III radial head and neck fractures: study protocol for a systematic review in accordance with the PRISMA statement.

    PubMed

    Hagelberg, Mårten; Thune, Alexandra; Krupic, Ferid; Salomonsson, Björn; Sköldenberg, Olof

    2017-01-27

    Fractures of the radial head and neck are the most common fractures of the elbow, and account for approximately one-third of all elbow fractures. Depending on the fracture type the treatment is either conservative or surgical. There is no absolute consensus regarding optimal treatment for different fracture types. The aim of this protocol is to present the method that will be used to collect, describe and analyse the current evidence regarding the treatment of Mason II-III radial head and neck fractures. We will conduct a systematic review in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocol (PRISMA-P) guidelines statement. We will search a number of databases with a predefined search strategy to collect both randomised and non-randomised studies. The articles will be summarised with descriptive statistics. If applicable a meta-analysis will be conducted. Ethical approval is not required since this is a protocol for a systematic review and no primary data will be collected. The authors will publish findings from this review in a peer-reviewed scientific journal. CRD42016037627. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  9. Ion paired chromatography of iron (II,III), nickel (II) and copper (II) as their 4,7-Diphenyl-1,10-phenanthroline chelates.

    PubMed

    Mudasir; Yoshioka, N; Inoue, H

    1997-07-01

    A reversed phase ion-paired chromatographic method that can be used to determine trace amounts of iron (II,III), nickel (II) and copper (II) was developed and applied to the determination of iron (II) and iron (III) levels in natural water. The separation of these metal ions as their 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline) chelates on an Inertsil ODS column was investigated by using acetonitrile-water (80/20, v/v) containing 0.06 M perchloric acid as mobile phase and diode array spectrophotometric detection at 250-650 nm. Chromatographic parameters such as composition of mobile phase and concentration of perchloric acid in mobile phase were optimized. The calibration graphs of iron (II), nickel (II) and copper (II) ions were linear (r > 0.991) in the concentration range 0-0.5, 0-2.0 and 0-4.0 mug ml(-1), respectively. The detection limit of iron (II), nickel (II) and copper (II) were 2.67, 5.42 and 18.2 ng ml(-1) with relative standard deviation (n = 5) of 3.11, 5.81 and 7.16% at a concentration level of 10 ng ml(-1) for iron (II) and nickel (II) and 25 ng ml(-1) for copper (II), respectively. The proposed method was applied to the determination of iron(II) and iron(III) in tap water and sea water samples without any interference from other common metal ions.

  10. Integrated Fast Neutron Flux at the End of Phases I, II, III, and IV-1B of the MOX Zr-cladding Tube

    SciTech Connect

    Gray Chang

    2004-03-01

    This report using the detailed ATR quarter core model calculated neutronic tallies, the MCWO-calculated Zr-cladding fast neutron fluence (E > 0.1 MeV and E > 1.0 MeV) distributions at the end of Phase-I, -II, -III, and -IV Irradiation are tabulated in Table 1, 2, 3, and 4. At the end of the Phase-I irradiation, the MCWO-calculated Zr-cladding fast neutron fluences of the removed MOX capsules 1 and 8 are 2.68 and 2.68 x 1020 n/cm2, respectively. At the end of Phase-II Irradiation are tabulated in Table 2. At the end of the Phase-II irradiation, the MCWO-calculated Zr-cladding fast neutron fluences of the removed MOX capsules 9 and 2 are 6.78 and 6.79 x 1020 n/cm2, respectively. At the end of the Phase-III irradiation, the MCWO-calculated Zr-cladding fast neutron fluences of the removed MOX capsules 10 and 3 are 9.82 and 9.70 x 1020 n/cm2, respectively. And, at the end of the Phase-IV part 1B irradiation, the MCWO-calculated Zr-cladding fast neutron fluences of the removed MOX capsules 4 and 13 are 1.41 and 1.39 x 1021 n/cm2, respectively.

  11. Assessment of oxidative stress and chromosomal aberration inducing potential of three medical grade silicone polymer materials.

    PubMed

    Vijayalakshmi, P; Geetha, C S; Mohanan, P V

    2013-02-01

    Medical expenditures for devices are increasing along with the ageing of human population and the synthesis of materials such as silicone polymers is on upsurge for manufacturing these devices. The International Organization for Standardization (ISO) emphasizes a battery of tests for preclinical assessment of biocompatibility of medical devices. Genotoxicity assays have become an integral component of these test procedures and it employs a set of in vitro and in vivo experiments to detect mutagens. Hence, this study was performed with an intention to investigate the genotoxic potential of the physiological saline extracts of three medical grade silicone polymer materials by the in vitro chromosomal aberration assay using human peripheral blood lymphocytes. Further, the oxidative stress inducing potential of the material extracts was investigated in vivo in mice liver homogenates using cyclophosphamide as positive control. The investigation revealed that none of the three materials were able to produce marked human lymphocyte chromosomal aberration, suggesting the absence of mutagens. The materials also showed negative results in their oxidative stress inducing potential, which was revealed by the normal levels of lipid peroxidation and unaltered levels of glutathione and its metabolizing enzymes in the mice liver tissue homogenates. It was interesting to observe a significant correlation between the genotoxic and antioxidant parameters investigated. Hence, it is suggested that the estimation of antioxidant status would serve as a better preliminary testing procedure prior to evaluating the genetic and molecular toxicity mechanisms of medical devices and/or materials intended for manufacture of such devices.

  12. Theoretical Determination of One-Electron Oxidation Potentials for Nucleic Acid Bases.

    PubMed

    Psciuk, Brian T; Lord, Richard L; Munk, Barbara H; Schlegel, H Bernhard

    2012-12-11

    The oxidation potentials for N-methyl substituted nucleic acid bases guanine, adenine, cytosine, thymine, uracil, xanthine, and 8-oxoguanine were computed using B3LYP and CBS-QB3 with the SMD solvation model. Acid-base and tautomeric equilibria present in aqueous solution were accounted for by combining standard redox potentials with calculated pKa and tautomerization energies to produce an ensemble averaged pH dependent potential. Gas phase free energies were computed using B3LYP/aug-cc-pVTZ//B3LYP/6-31+G(d,p) and CBS-QB3. Solvation free energies were computed at the SMD/B3LYP/6-31+G(d,p) level of theory. Compared to experimental results, calculations with the CBS-QB3 level of theory have a mean absolute error (MAE) of ca. 1 kcal/mol for the gas phase proton affinity/gas phase basicity and an MAE of ca. 0.04 eV for the adiabatic/vertical ionization potentials. The B3LYP calculations have a MAE of ∼2 kcal/mol for the proton affinity/gas phase basicity data but systematically underestimated ionization potentials by 0.14-0.21 eV. Solvent cavities for charged solute species were rescaled uniformly by fitting computed pKa data to experimentally measured pKa values. After solvent cavity scaling, the MAEs for computed pKa's compared to experimental results are 0.7 for B3LYP and 0.9 for CBS-QB3. In acetonitrile, the computed E°(XH(+•)/XH) redox potentials are systematically lower than experimentally measured potentials by 0.21 V for CBS-QB3 and 0.33 V for B3LYP. However, the redox potentials relative to adenine are in very good agreement with experimental results, with MAEs of 0.10 V for CBS-QB3 and 0.07 V for B3LYP. In aqueous solution, B3LYP and CBS-QB3 have MAEs of 0.21 and 0.19 V for E7(X(•),H(+)/XH). Replacing the methyl substituent with ribose changes the calculated E7 potentials by 0.1-0.2 V. The calculated difference between the guanine and adenine oxidation potentials is too large compared to experimental results, but the calculated difference between

  13. [Intraoperative pain stimuli change somatosensory evoked potentials, but not auditory evoked potentials during isoflurane/nitrous oxide anesthesia].

    PubMed

    Rundshagen, I; Kochs, E; Bischoff, P; Schulte am Esch, J

    1997-10-01

    Evoked potentials are used for intraoperative monitoring to assess changes of cerebral function. This prospective randomised study assesses the influence of surgical stimulation on midlatency components of somatosensory (SEPs) and auditory evoked potentials (AEPs) in anaesthetised patients. After approval of the Ethics Committee and written informed consent 36 orthopaedic patients (34 +/- 15 y, 73 +/- 14 kg. 1.71 +/- 0.07 m, ASA I-II) were randomly included in the study. Anaesthesia was induced with 1.5 micrograms/kg fentanyl, 0.3 mg/kg etomidate and 0.1 mg/kg vecuronium. The lungs were intubated and patients normoventilated in steady state anaesthesia with isoflurane (end-tidal 0.6%) and 66% nitrous oxide. 18 patients (group 1) were assigned to the SEP group: median nerve stimulation, recording at Erb, C 6 and the contralateral somatosensory cortex (N20, P25, N35) vs Fz. AEPs were recorded in group 2 (n = 18): binaural stimulation, recording at Cz versus linked mastoid (V, Na, Pa, Nb). Recordings were performed during 30 min before the start of surgery (baseline: BL), at skin incision (SURG1) and at the preparation of the periost (SURG2). Heart rate, mean arterial blood pressure, oxygen saturation, endtidal pCO2 and isoflurane (PetISO) concentrations were registered simultaneously. Data were analysed by one-way analysis of variance. Post hoc comparison were made by Mann-Whitney U-Wilcoxon Rank Sum Test with p < 0.05 significant. During steady state isoflurane anaesthesia surgical stimulation (SURG2) resulted in significant increases of N20 P25 amplitudes compared with BL (BL: 1.4 +/- 0.7 microV; SURG2: 2.0 +/- 0.8 microV; p < 0.05). Latencies of SEPs and midlatency components of AEPs did not change over time. There were no differences in autonomic parameters between SEP and AEP groups. MAP increased from 76 +/- 6 mmHg at BL to 93 +/- 16 mmHg at SURG1 and 96 +/- 17 mmHg at SURG2 (n = 36; p < 0.05). HR increased from BL (60 +/- 8 beats/min) to SURG2 (76 +/- 12 beats

  14. Evaluation of anti-inflammatory and anti-oxidant potential of seed extracts of Vernonia anthelmintica.

    PubMed

    Jamil, Subia; Khan, Rafeeq Alam; Ahmed, Shadab; Fatima, Sakina

    2017-05-01

    Seeds of Vernonia anthelmintica in the form of Ethanol seed extract of Vernonia anthelmintica (EEVA), Hexane extract of Vernonia anthelmintica (HEVA) and water decoction of Vernonia anthelmintica (WDVA) were evaluated for their in-vivo anti-Inflammatory potential in carrageenan induced rat paw model. The results were compared to anti-inflammatory activity of standard drug (ibuprofen) and untreated groups. In-vitro evaluation of antioxidant potential of EEVA and HEVA were also conducted by "DPPH scavenging assay". The results of present study depicts that HEVA and EEVA in higher dose possess a strong anti-inflammatory potential as compared to standard anti-inflammatory drugs, whereas WDVA showed milder anti-inflammatory potential. DPPH assay has revealed strong anti-oxidant potential of EEVC with the percentage Radical Scavenging activity (%RSA) of 89.709 at concentrations of 500 ul as compared to standard drugs gallic acid (23.436±0.43) and acetyl salicylic acid (111.44±0.7) at concentrations of 95.95 μM. The other extract HEVC has shown to have insignificant %RSA at the concentration of 500μl. Hence the present study revealed that selected extracts of Vernonia anthelmintica exhibited significant in-vitro antioxidant and in-vivo anti-inflammatory potential.

  15. Draft Genome Sequence of a Potential Nitrate-Dependent Fe(II)-Oxidizing Bacterium, Aquabacterium parvum B6

    PubMed Central

    Zhang, Xiaoxin

    2016-01-01

    Aquabacterium parvum B6 is a potential nitrate-dependent Fe(II)-oxidizing bacterium. The genes related to its denitrifying mechanism and iron metabolisms were unknown. We present the draft genome of Aquabacterium parvum B6, which could provide further insight into the nitrate-dependent Fe(II)-oxidizing mechanism of strain B6. PMID:26823591

  16. Draft Genome Sequence of a Potential Nitrate-Dependent Fe(II)-Oxidizing Bacterium, Aquabacterium parvum B6.

    PubMed

    Zhang, Xiaoxin; Ma, Fang; Szewzyk, Ulrich

    2016-01-28

    Aquabacterium parvum B6 is a potential nitrate-dependent Fe(II)-oxidizing bacterium. The genes related to its denitrifying mechanism and iron metabolisms were unknown. We present the draft genome of Aquabacterium parvum B6, which could provide further insight into the nitrate-dependent Fe(II)-oxidizing mechanism of strain B6. Copyright © 2016 Zhang et al.

  17. The nitric oxide/cyclic GMP pathway: a potential major regulator of cochlear physiology.

    PubMed

    Fessenden, J D; Schacht, J

    1998-04-01

    The nitric oxide (NO)/cyclic guanosine monophosphate (GMP) pathway is now recognized as a major regulatory system in cell physiology and tissue homeostasis. This pathway may control processes as diverse as muscle relaxation, gut peristalsis, neurotransmission and hormonal secretion. It is also involved in the development and function of sensory systems such as vision and olfaction. This review will detail the NO/cyclic GMP pathway, evaluate studies in the auditory system and discuss its potential participation in cochlear blood flow, supporting cell physiology and excitotoxicity.

  18. Stationary market applications potential of solid oxide and solid polymer fuel cell systems

    SciTech Connect

    Baker, J.N.; Fletcher, W.H.

    1996-12-31

    The UK DTI`s Advanced Fuel Cells Programme currently focuses on two main fuel cell technologies, namely the solid oxide and solid polymer systems (SOFC and SPFC), respectively. The provision of accurate and timely market data is regarded as an important part of the overall programme objectives, such as to assist both Government and industry in their appraisals of the technologies. The present study was therefore commissioned against this background, with a complementary study addressing transportation and mobile applications. The results reported herein relate to the stationary market applications potential of both SOFC and SPFC systems.

  19. Determination of the oxidation potentials of organic benzene derivatives: theory and experiment

    NASA Astrophysics Data System (ADS)

    Han, Young-Kyu; Jung, Jaehoon; Cho, Jeong-Ju; Kim, Hyeong-Jin

    2003-01-01

    We have calculated the IP, Δ Ge, and Eox values for 10 mono-substituted benzene molecules and compared them with experimental values obtained by linear sweep voltammetry. The Eox values were evaluated using the density functional method and thermodynamic cycles. The relative oxidation potentials are in close agreement with experimental values, while the UB3LYP/6-31+G(d) approach shows the absolute Eox values to be lower by about 0.9 V. Consideration of bulk solvent effects is important to fully describe the experimental variation in Eox. The HOMO, NBO, and Wiberg bond index were analyzed to investigate the changes when moving from neutral to cationic molecules.

  20. Influence of the semiconductor oxidation potential on the operational stability of organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Sharma, A.; Mathijssen, S. G. J.; Bobbert, P. A.; de Leeuw, D. M.

    2011-09-01

    During prolonged application of a gate bias, organic field-effect transistors show a gradual shift of the threshold voltage towards the applied gate bias voltage. The shift follows a stretched-exponential time dependence governed by a relaxation time. Here, we show that a thermodynamic analysis reproduces the observed exponential dependence of the relaxation time on the oxidation potential of the semiconductor. The good fit with the experimental data validates the underlying assumptions. It demonstrates that this operational instability is a straightforward thermodynamically driven process that can only be eliminated by eliminating water from the transistor.

  1. Oxidative DNA damage protective activity, antioxidant and anti-quorum sensing potentials of Moringa oleifera.

    PubMed

    Singh, Brahma N; Singh, B R; Singh, R L; Prakash, D; Dhakarey, R; Upadhyay, G; Singh, H B

    2009-06-01

    The aqueous extract of leaf (LE), fruit (FE) and seed (SE) of Moringa oleifera was assessed to examine the ability to inhibit the oxidative DNA damage, antioxidant and anti-quorum sensing (QS) potentials. It was found that these extracts could significantly inhibit the OH-dependent damage of pUC18 plasmid DNA and also inhibit synergistically with trolox, with an activity sequence of LE > FE > SE. HPLC and MS/MS analysis was carried out, which showed the presence of gallic acid, chlorogenic acid, ellagic acid, ferulic acid, kaempferol, quercetin and vanillin. The LE was with comparatively higher total phenolics content (105.04 mg gallic acid equivalents (GAE)/g), total flavonoids content (31.28 mg quercetin equivalents (QE)/g), and ascorbic acid content (106.95 mg/100 g) and showed better antioxidant activity (85.77%), anti-radical power (74.3), reducing power (1.1 ascorbic acid equivalents (ASE)/ml), inhibition of lipid peroxidation, protein oxidation, OH-induced deoxyribose degradation, and scavenging power of superoxide anion and nitric oxide radicals than did the FE, SE and standard alpha-tocopherol. Eventually, LE and FE were found to inhibit violacein production, a QS-regulated behavior in Chromobacterium violaceum 12472.

  2. Antioxidant potential of tea reduces arsenite induced oxidative stress in Swiss albino mice.

    PubMed

    Sinha, D; Roy, S; Roy, M

    2010-04-01

    Environmental arsenic (As) is a potent human carcinogen and groundwater As contamination is a major health concern in West Bengal, India. Oxidative stress has been one of the prime factors in As-induced carcinogenicity. Generation of reactive oxygen species (ROS), beyond the body's endogenous antioxidant balance cause a severe imbalance of the cellular antioxidant defence mechanism. Tea, a popular beverage has excellent chemopreventive and antioxidant properties. In this study it was investigated whether these flavonoids could ameliorate the arsenite (As III) induced oxidative stress in Swiss albino mice. Bio-monitoring with comet assay elicited that the increase in genotoxicity caused by As III was counteracted by both black tea and green tea. Elevated levels of lipid peroxides and protein carbonyl by As III were effectively reduced with green as well as black tea. They also exhibited protective action against the As III induced depletion of antioxidants like catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) and glutathione (GSH) in mice liver tissue. Thus the tea polyphenols by virtue of their antioxidant potential may be used as an effective agent to reduce the As III induced oxidative stress in Swiss albino mice.

  3. Role of oxidative stress & transient receptor potential in chronic obstructive pulmonary disease

    PubMed Central

    Bose, Protiti; Bathri, Rashmi; Kumar, Lalit; Vijayan, V.K.; Maudar, K.K.

    2015-01-01

    Chronic obstructive pulmonary disease (COPD) affect millions of people worldwide and is known to be one of the leading causes of death. The highly sensitive airways protect themselves from irritants by cough and sneeze which propel endogenous and exogenous substances to minimize airway noxious effects. One noxious effect of these substances is activation of peripheral sensory nerve endings of nociceptor neurons innervating these airways lining thus transmitting dangerous signals from the environment to the central nervous system (CNS). Nociceptor neurons include transient receptor potential (TRP) ion channels, especially the vanilloid and ankyrin subfamilies, TRPV1/A1 which can be activated by noxious chemical challenges in models of airways disease. As oxidative stress may activate airways sensory neurons and contribute to COPD exacerbations we sought to review the role that TRP channel activation by oxidative signals may have on airway responses. It would be prudent to target the TRP channels with antagonists and lower systemic oxidative stress with agents that can modulate TRP expression and boost the endogenous levels of antioxidants for treatment and management of COPD. PMID:26458340

  4. Cerium oxide nanoparticles prevent apoptosis in primary cortical culture by stabilizing mitochondrial membrane potential.

    PubMed

    Arya, A; Sethy, N K; Das, M; Singh, S K; Das, A; Ujjain, S K; Sharma, R K; Sharma, M; Bhargava, K

    2014-07-01

    Cerium oxide nanoparticles (CNPs) of spherical shape have unique antioxidant capacity primarily due to alternating + 3 and + 4 oxidation states and crystal defects. Several studies revealed the protective efficacies of CNPs in cells and tissues against the oxidative damage. However, its effect on mitochondrial functioning, downstream effectors of radical burst and apoptosis remains unknown. In this study, we investigated whether CNPs treatment could protect the primary cortical cells from loss of mitochondrial membrane potential (Δψm) and Δψm-dependent cell death. CNPs with spherical morphology and size range 7-10 nm were synthesized and utilized at a concentration of 25 nM on primary neuronal culture challenged with 50 μM of hydrogen peroxide (H2O2). We showed that optimal dose of CNPs minimized ROS content of the cells and also curbed related surge in cellular calcium flux. Importantly, CNPs treatment prevented apoptotic loss of cell viability. Reduction in the apoptosis could be successfully attributed to the maintenance of Δψm and restoration of major redox equivalents NADH/NAD(+) ratio and cellular ATP. These findings, therefore, suggest possible route of CNPs protective efficacies in primary cortical culture.

  5. A potential link of oxidative stress and cell cycle regulation for development of endometriosis.

    PubMed

    Shigetomi, Hiroshi; Higashiura, Yumi; Kajihara, Hirotaka; Kobayashi, Hiroshi

    2012-11-01

    The roles of molecular alteration such as genomic instability and cell survival are debated aspects of the pathogenesis of endometriosis. To review the contemporary literature on potential factors and their signaling pathways that support prolonged survival of endometriotic cells. This article reviews the English-language literature for molecular, pathogenetic, and pathophysiological studies on endometriosis. This review is focused on the association of hepatocyte nuclear factor (HNF)-1β with endometriosis. The iron-induced oxidative stress plays a fundamental role for the pathogenesis of endometriosis. Oxidative stress, secondary to influx of iron during retrograde menstruation, modifies lipids and proteins, leading to cell and DNA damage. Recent studies demonstrated HNF-1β overexpression in endometriotic foci. HNF-1β increases the survival of endometriotic cells under iron-induced oxidative stress conditions possibly through the activation of forkhead box (FOX) transcription factors and/or endometriosis-specific expression of microRNAs. Endometriotic cells expressing HNF-1β also display cell cycle checkpoint pathways required to survive DNA damaging events. HNF-1β in endometriosis might be a factor that controls the cell cycle and DNA damage checkpoints.

  6. Metal Oxide Nanomaterials in Nanomedicine: Applications in Photodynamic Therapy and Potential Toxicity.

    PubMed

    He, Xiaojia; Aker, Winfred G; Huang, Ming-Ju; Watts, John D; Hwang, Huey-Min

    2015-01-01

    Metal oxide nanomaterials have exhibited excellent performance as nanomedicines in photodynamic therapy (PDT) for cancer and infection treatment. Their unique and tunable physicochemical properties advance them as promising alternatives in drug delivery, early diagnosis, imaging, and treatment against various tumors and infectious diseases. Moreover, the implementation of nanophototherapy in deep tissue sites is enhanced by advancements in photosensitization technology. Notwithstanding the progress made in emerging metal oxide nanomaterials-derived PDT, the potential toxicity towards adjunct tissues associated with this approach remains challenging. Regulation and legislation have also been recommended and subsequently enacted in response to public concerns related to large-scale production, transportation, use, and disposal of those nanomaterials. Consequently, a quantitative structure-activity relationship (QSAR) paradigm has been adopted and is widely used in evaluating and predicting the side effects of nanomedicines, thus influencing their design and fabrication. This article briefly reviews the application of metal oxide nanomaterials in PDT and their associated adverse impacts as reported in recent publications. The future trends and implications of this platform in nanomedicine are also highlighted. However, more studies and efforts have to be carried out for developing novel nano-therapeutics with high selectivity, sensitivity, biocompatibility, and minimal side effects in PDT.

  7. Hydrogen Peroxide Cycling in Acidic Geothermal Environments and Potential Implications for Oxidative Stress

    NASA Astrophysics Data System (ADS)

    Mesle, M.; Beam, J.; Jay, Z.; Bodle, B.; Bogenschutz, E.; Inskeep, W.

    2014-12-01

    Hydrogen peroxide (H2O2) may be produced in natural waters via photochemical reactions between dissolved oxygen, organic carbon and light. Other reactive oxygen species (ROS) such as superoxide and hydroxyl radicals are potentially formed in environments with high concentrations of ferrous iron (Fe(II), ~10-100 μM) by reaction between H2O2 and Fe(II) (i.e., Fenton chemistry). Thermophilic archaea and bacteria inhabiting acidic iron-oxide mats have defense mechanisms against both extracellular and intracellular peroxide, such as peroxiredoxins (which can degrade H2O2) and against other ROS, such as superoxide dismutases. Biological cycling of H2O2 is not well understood in geothermal ecosystems, and geochemical measurements combined with molecular investigations will contribute to our understanding of microbial response to oxidative stress. We measured H2O2 and other dissolved compounds (Fe(II), Fe(III), H2S, O2), as well as photon flux, pH and temperature, over time in surface geothermal waters of several acidic springs in Norris Geyser Basin, Yellowstone National Park, WY (Beowulf Spring and One Hundred Spring Plain). Iron-oxide mats were sampled in Beowulf Spring for on-going analysis of metatranscriptomes and RT-qPCR assays of specific stress-response gene transcription (e.g., superoxide dismutases, peroxiredoxins, thioredoxins, and peroxidases). In situ analyses show that H2O2 concentrations are lowest in the source waters of sulfidic systems (ca. 1 μM), and increase by two-fold in oxygenated waters corresponding to Fe(III)-oxide mat formation (ca. 2 - 3 μM). Channel transects confirm increases in H2O2 as a function of oxygenation (distance). The temporal dynamics of H2O2, O2, Fe(II), and H2S in Beowulf geothermal waters were also measured during a diel cycle, and increases in H2O2 were observed during peak photon flux. These results suggest that photochemical reactions may contribute to changes in H2O2. We hypothesize that increases in H2O2 and O2

  8. Experimental insights into organic carbon oxidation potential during fluvial transport without floodplain storage

    NASA Astrophysics Data System (ADS)

    Scheingross, J. S.; Hovius, N.; Sachse, D.; Vieth-Hillebrand, A.; Turowski, J. M.; Hilton, R. G.

    2016-12-01

    Over geologic timescales, the exchange of organic carbon (OC) between the atmosphere, rock, and biosphere is thought to be a major control on global climate. CO2 flux estimates from oxidation of rock-derived OC and sequestration of biospheric OC during fluvial transit from source to sink are approximately the same order of magnitude or larger than those from silicate weathering. Despite field data showing loss of OC moving downstream in lowland rivers, it is unclear if losses occur primarily during active fluvial transport within the river, where OC is in continual motion within an aerated environment, or during longer periods when OC is temporarily stored in river floodplains which may be anoxic. This represents a major knowledge gap, as the unknown location of OC oxidation (i.e., river vs. floodplain) limits our ability to develop process-based models that can be employed to predict OC losses, constrain carbon budgets, and unravel links between climate, tectonics, and erosion. To fill this gap, we investigated the potential for OC oxidation in laboratory experiments simulating fluvial transport without floodplain storage. Mixtures of OC-rich and siliciclastic sediment were transported for distances of 2000 km in annular flumes while making time-series measurements of sediment TOC and water DOC concentrations. Initial results for transport of OC-rich soil show increasing DOC with transport distance to levels that represent a transfer of 2% of the total OC from the solid to the dissolved phase; however, we observed no detectable change in the solid-phase TOC. Similar results were obtained in a control experiment with identical sediment in still water. These preliminary results suggest minimal OC oxidation within our experiment, and, to the extent that such experiments represent natural transport through river systems, are consistent with the hypothesis that OC losses may occur primarily during floodplain storage rather than fluvial transport.

  9. Potential biological efficacy of Pinus plant species against oxidative, inflammatory and microbial disorders.

    PubMed

    Sharma, Aditi; Goyal, Rohit; Sharma, Lalit

    2016-01-28

    Traditionally, Pine has been used to treat oxidative and inflammatory disorders. The study was aimed to investigate biological potential of phytoconstituents of Pinus plant species: Pinus roxburghii, Pinus wallichiana and Pinus gerardiana using in-vitro antioxidant, anti-inflammatory and antimicrobial methods. The hydro-alcoholic extraction of dried plant: stem bark was done and the antioxidant activity was evaluated using free radical scavenging methods for 1,1-diphenyl-2-picrylhydrazyl, (DPPH), nitric oxide and hydrogen peroxide radicals, reducing power assays, and total antioxidant capacity. Anti-inflammatory activity was carried out using albumin denaturation and HRBC membrane stabilization assays. Antimicrobial and antifungal activities were also conducted using agar well diffusion method. The qualitative phytochemical analysis of hydro-alcoholic stem bark extracts of three plant species revealed the presence of various biochemical compounds such as alkaloids, flavonoids, glycosides, triterpenoids and saponins. Quantitative phytochemical analysis of plant extracts showed the presence of phenolics, flavonoids, tannins, beta-carotene and lycopene. Plant extracts of three pinus species showed significant antioxidant activity against DPPH, nitric oxide and H2O2 radicals. In in-vitro anti-inflammatory investigation, Pinus roxburghii exhibited highest protection against albumin denaturation 86.54 ± 1.85 whereas Pinus gerardiana showed 82.03 ± 2.67. Moreover, plant extracts were found to prevent the growth of microorganisms Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans showing promising antibacterial and antifungal activities againstCandida albicans. The findings of the present study derived the rational for the therapeutic usage of Pinus which is a highly timber yielding plant from Himalayan region, against oxidative, inflammatory and microbial diseases.

  10. Isolation and characterization of sulphur-oxidizing Thiomonas sp. and its potential application in biological deodorization.

    PubMed

    Chen, X-G; Geng, A-L; Yan, R; Gould, W D; Ng, Y-L; Liang, D T

    2004-01-01

    To isolate and characterize a sulphur-oxidizing bacterial strain from activated sludge and to evaluate its potential application in biological deodorization. A dominant sulphur-oxidizing bacterial strain, designated as strain SS, was isolated from an enrichment culture using thiosulphate as a sole energy source and CO2 as a sole carbon source. The cells of this organism were aerobic, rod-shaped, Gram-negative and motile. Strain SS could grow autotrophically, heterotrophically as well as mixotrophically. Autotrophic growth was observed at pH values ranging from 2.3 to 9.0. Phylogenetic analyses revealed that strain SS belonged to Group 1 of the genus Thiomonas, closely related to Thiomonas perometabolis and Thiomonas intermedia. The thiosulphate oxidation rates of strain SS at different pH values were evaluated in terms of oxygen uptake using a Micro-Oxymax respirometer. The results showed that the maximum oxidation rate of 5.65 mg l(-1) h(-1) occurred at 56 h of growth and pH 6.0. Continuous H2S removal study demonstrated that strain SS could remove more than 99% of H2S when the inlet concentration was below 58.6 ppm. Further increase of the inlet concentration to 118 ppm gave rise to a decline in the removal efficiency to ca 90%. The strong acidification of the culture medium during the later period could result in the deterioration of the growth activity and the metabolism activity of strain SS. In practical application, the problems caused by the end-product inhibition and the acidification can be alleviated by periodical replacement of culture medium with fresh medium. Given the physiological flexibility and the ability to remove H2S rapidly and efficiently, strain SS could be a good 'deodorizing' candidate. This is the first time that Thiomonas species has been reported for biological deodorization application.

  11. Long Interspersed Nuclear Element-1 Hypomethylation and Oxidative Stress: Correlation and Bladder Cancer Diagnostic Potential

    PubMed Central

    Amnattrakul, Passakorn; Dissayabutra, Thasinas; Mutirangura, Apiwat; Tosukhowong, Piyaratana

    2012-01-01

    Although, increased oxidative stress and hypomethylation of long interspersed nuclear element-1 (LINE-1) associate with bladder cancer (BCa) development, the relationship between these alterations is unknown. We evaluated the oxidative stress and hypomethylation of the LINE-1 in 61 BCa patients and 45 normal individuals. To measure the methylation levels and to differentiate the LINE-1 loci into hypermethylated, partially methylated and hypomethylated, peripheral blood cells, urinary exfoliated cells and cancerous tissues were evaluated by combined bisulfite restriction analysis PCR. The urinary total antioxidant status (TAS) and plasma protein carbonyl content were determined. The LINE-1 methylation levels and patterns, especially hypomethylated loci, in the blood and urine cells of the BCa patients were different from the levels and patterns in the healthy controls. The urinary TAS was decreased, whereas the plasma protein carbonyl content was increased in the BCa patients relative to the controls. A positive correlation between the methylation of LINE-1 in the blood-derived DNA and urinary TAS was found in both the BCa and control groups. The urinary hypomethylated LINE-1 loci and the plasma protein carbonyl content provided the best diagnostic potential for BCa prediction. Based on post-diagnostic samples, the combination test improved the diagnostic power to a sensitivity of 96% and a specificity of 96%. In conclusion, decreased LINE-1 methylation is associated with increased oxidative stress both in healthy and BCa subjects across the various tissue types, implying a dose-response association. Increases in the LINE-1 hypomethylation levels and the number of hypomethylated loci in both the blood- and urine-derived cells and increase in the oxidative stress were found in the BCa patients. The combination test of the urinary hypomethylated LINE-1 loci and the plasma protein carbonyl content may be useful for BCa screening and monitoring of treatment. PMID

  12. Metal oxide-based nanoparticles: revealing their potential to enhance oil recovery in different wettability systems

    NASA Astrophysics Data System (ADS)

    Hendraningrat, Luky; Torsæter, Ole

    2015-02-01

    This paper presents systematic studies of hydrophilic metal oxide nanoparticles (NPs) dispersed in brine intended to reveal their potential to enhance oil recovery (EOR) in various rock wettability systems. The stability in suspension (nanofluid) of the NPs has been identified as a key factor related to their use as an EOR agent. Experimental techniques have been developed for nanofluid stability using three coupled methods: direct visual observation, surface conductivity and particle size measurements. The use of a dispersant has been investigated and has been shown to successfully improve metal oxide nanofluid stability as a function of its concentration. The dispersant alters the nanofluid properties, i.e. surface conductivity, pH and particle size distribution. A two-phase coreflood experiment was conducted by injecting the stable nanofluids as a tertiary process (nano-EOR) through core plugs with various wettabilities ranging from water-wet to oil-wet. The combination of metal oxide nanofluid and dispersant improved the oil recovery to a greater extent than either silica-based nanofluid or dispersant alone in all wettability systems. The contact angle, interfacial tension (IFT) and effluent were also measured. It was observed that metal oxide-based nanofluids altered the quartz plates to become more water-wet, and the results are consistent with those of the coreflood experiment. The particle adsorption during the transport process was identified from effluent analysis. The presence of NPs and dispersant reduced the IFT, but its reduction is sufficient to yield significant additional oil recovery. Hence, wettability alteration plays a dominant role in the oil displacement mechanism using nano-EOR.

  13. Long interspersed nuclear element-1 hypomethylation and oxidative stress: correlation and bladder cancer diagnostic potential.

    PubMed

    Patchsung, Maturada; Boonla, Chanchai; Amnattrakul, Passakorn; Dissayabutra, Thasinas; Mutirangura, Apiwat; Tosukhowong, Piyaratana

    2012-01-01

    Although, increased oxidative stress and hypomethylation of long interspersed nuclear element-1 (LINE-1) associate with bladder cancer (BCa) development, the relationship between these alterations is unknown. We evaluated the oxidative stress and hypomethylation of the LINE-1 in 61 BCa patients and 45 normal individuals. To measure the methylation levels and to differentiate the LINE-1 loci into hypermethylated, partially methylated and hypomethylated, peripheral blood cells, urinary exfoliated cells and cancerous tissues were evaluated by combined bisulfite restriction analysis PCR. The urinary total antioxidant status (TAS) and plasma protein carbonyl content were determined. The LINE-1 methylation levels and patterns, especially hypomethylated loci, in the blood and urine cells of the BCa patients were different from the levels and patterns in the healthy controls. The urinary TAS was decreased, whereas the plasma protein carbonyl content was increased in the BCa patients relative to the controls. A positive correlation between the methylation of LINE-1 in the blood-derived DNA and urinary TAS was found in both the BCa and control groups. The urinary hypomethylated LINE-1 loci and the plasma protein carbonyl content provided the best diagnostic potential for BCa prediction. Based on post-diagnostic samples, the combination test improved the diagnostic power to a sensitivity of 96% and a specificity of 96%. In conclusion, decreased LINE-1 methylation is associated with increased oxidative stress both in healthy and BCa subjects across the various tissue types, implying a dose-response association. Increases in the LINE-1 hypomethylation levels and the number of hypomethylated loci in both the blood- and urine-derived cells and increase in the oxidative stress were found in the BCa patients. The combination test of the urinary hypomethylated LINE-1 loci and the plasma protein carbonyl content may be useful for BCa screening and monitoring of treatment.

  14. Modeling and Investigation of Heavy Oxide and Alkali-Halide Scintillators for Potential Use in Neutron and Gamma Detection Systems

    DTIC Science & Technology

    2015-06-01

    INVESTIGATION OF HEAVY OXIDE AND ALKALI -HALIDE SCINTILLATORS FOR POTENTIAL USE IN NEUTRON AND GAMMA DETECTION SYSTEMS by Jeremy S. Cadiente June...AND ALKALI - HALIDE SCINTILLATORS FOR POTENTIAL USE IN NEUTRON AND GAMMA DETECTION SYSTEMS 5. FUNDING NUMBERS 6. AUTHOR(S) Jeremy S. Cadiente 7...CODE 13. ABSTRACT (maximum 200 words) Heavy inorganic oxide and alkali -halide crystals, which previous experimental research has indicated to have

  15. The reduction potential of nitric oxide (NO) and its importance to NO biochemistry.

    PubMed

    Bartberger, Michael D; Liu, Wei; Ford, Eleonora; Miranda, Katrina M; Switzer, Christopher; Fukuto, Jon M; Farmer, Patrick J; Wink, David A; Houk, Kendall N

    2002-08-20

    A potential of about -0.8 (+/-0.2) V (at 1 M versus normal hydrogen electrode) for the reduction of nitric oxide (NO) to its one-electron reduced species, nitroxyl anion (3NO-) has been determined by a combination of quantum mechanical calculations, cyclic voltammetry measurements, and chemical reduction experiments. This value is in accord with some, but not the most commonly accepted, previous electrochemical measurements involving NO. Reduction of NO to 1NO- is highly unfavorable, with a predicted reduction potential of about -1.7 (+/-0.2) V at 1 M versus normal hydrogen electrode. These results represent a substantial revision of the derived and widely cited values of +0.39 V and -0.35 V for the NO/3NO- and NO/1NO- couples, respectively, and provide support for previous measurements obtained by electrochemical and photoelectrochemical means. With such highly negative reduction potentials, NO is inert to reduction compared with physiological events that reduce molecular oxygen to superoxide. From these reduction potentials, the pKa of 3NO- has been reevaluated as 11.6 (+/-3.4). Thus, nitroxyl exists almost exclusively in its protonated form, HNO, under physiological conditions. The singlet state of nitroxyl anion, 1NO-, is physiologically inaccessible. The significance of these potentials to physiological and pathophysiological processes involving NO and O2 under reductive conditions is discussed.

  16. Potential for iron oxides to control metal releases in CO2 sequestration scenarios

    USGS Publications Warehouse

    Berger, P.M.; Roy, W.R.

    2011-01-01

    The potential for the release of metals into groundwater following the injection of carbon dioxide (CO2) into the subsurface during carbon sequestration projects remains an open research question. Changing the chemical composition of even the relatively deep formation brines during CO2 injection and storage may be of concern because of the recognized risks associated with the limited potential for leakage of CO2-impacted brine to the surface. Geochemical modeling allows for proactive evaluation of site geochemistry before CO2 injection takes place to predict whether the release of metals from iron oxides may occur in the reservoir. Geochemical modeling can also help evaluate potential changes in shallow aquifers were CO2 leakage to occur near the surface. In this study, we created three batch-reaction models that simulate chemical changes in groundwater resulting from the introduction of CO2 at two carbon sequestration sites operated by the Midwest Geological Sequestration Consortium (MGSC). In each of these models, we input the chemical composition of groundwater samples into React??, and equilibrated them with selected mineral phases and CO 2 at reservoir pressure and temperature. The model then simulated the kinetic reactions with other mineral phases over a period of up to 100 years. For two of the simulations, the water was also at equilibrium with iron oxide surface complexes. The first model simulated a recently completed enhanced oil recovery (EOR) project in south-central Illinois in which the MGSC injected into, and then produced CO2, from a sandstone oil reservoir. The MGSC afterwards periodically measured the brine chemistry from several wells in the reservoir for approximately two years. The sandstone contains a relatively small amount of iron oxide, and the batch simulation for the injection process showed detectable changes in several aqueous species that were attributable to changes in surface complexation sites. After using the batch reaction

  17. Indium oxide thin film as potential photoanodes for corrosion protection of stainless steel under visible light

    SciTech Connect

    Zhang, Yan; Yu, Jianqiang; Sun, Kai; Zhu, Yukun; Bu, Yuyu; Chen, Zhuoyuan

    2014-05-01

    Graphical abstract: If the conduction band potential of In{sub 2}O{sub 3} is more negative than the corrosion potential of stainless steel, photo-induced electrons will be transferred from In{sub 2}O{sub 3} to the steel, thus shifting the potential of the steel into a corrosion immunity region and preventing the steel from the corrosion. - Highlights: • Indium oxide performed novel application under visible light. • Indium oxide by sol–gel method behaved better photoelectrochemical properties. • Electrons were transferred to stainless steel from indium oxide once light on. - Abstract: This paper reports the photoelectrochemical cathodic protection of 304 stainless steel by In{sub 2}O{sub 3} thin-film under visible-light. The films were fabricated with In{sub 2}O{sub 3} powders, synthesized by both sol–gel (In{sub 2}O{sub 3}-sg) and solid-state (In{sub 2}O{sub 3}-ss) processes. The photo-induced open circuit potential and the photo-to-current efficiency measurements suggested that In{sub 2}O{sub 3} could be a promising candidate material for photoelectrochemical cathodic protection of metallic alloys under visible light. Moreover, the polarization curve experimental results indicated that In{sub 2}O{sub 3}-sg thin-film can mitigate the corrosion potential of 304 stainless steel to much more negative values with a higher photocurrent density than the In{sub 2}O{sub 3}-ss film under visible-light illumination. All the results demonstrated that the In{sub 2}O{sub 3}-sg thin-film provides a better photoelectrochemical cathodic protection for 304 stainless steel than In{sub 2}O{sub 3}-ss thin-film under visible-light illumination. The higher photoelectrochemical efficiency is possibly due to the uniform thin films produced with the smaller particle size of In{sub 2}O{sub 3}-sg, which facilitates the transfer of the photo-induced electrons from bulk to the surface and suppresses the charge recombination of the electrons and holes.

  18. Ab initio intermolecular potential energy surface and thermophysical properties of nitrous oxide

    NASA Astrophysics Data System (ADS)

    Crusius, Johann-Philipp; Hellmann, Robert; Hassel, Egon; Bich, Eckard

    2015-06-01

    We present an analytical intermolecular potential energy surface (PES) for two rigid nitrous oxide (N2O) molecules derived from high-level quantum-chemical ab initio calculations. Interaction energies for 2018 N2O-N2O configurations were computed utilizing the counterpoise-corrected supermolecular approach at the CCSD(T) level of theory using basis sets up to aug-cc-pVQZ supplemented with bond functions. A site-site potential function with seven sites per N2O molecule was fitted to the pair interaction energies. We validated our PES by computing the second virial coefficient as well as shear viscosity and thermal conductivity in the dilute-gas limit. The values of these properties are substantiated by the best experimental data.

  19. Ab initio intermolecular potential energy surface and thermophysical properties of nitrous oxide

    SciTech Connect

    Crusius, Johann-Philipp Hassel, Egon; Hellmann, Robert Bich, Eckard

    2015-06-28

    We present an analytical intermolecular potential energy surface (PES) for two rigid nitrous oxide (N{sub 2}O) molecules derived from high-level quantum-chemical ab initio calculations. Interaction energies for 2018 N{sub 2}O–N{sub 2}O configurations were computed utilizing the counterpoise-corrected supermolecular approach at the CCSD(T) level of theory using basis sets up to aug-cc-pVQZ supplemented with bond functions. A site-site potential function with seven sites per N{sub 2}O molecule was fitted to the pair interaction energies. We validated our PES by computing the second virial coefficient as well as shear viscosity and thermal conductivity in the dilute-gas limit. The values of these properties are substantiated by the best experimental data.

  20. Iridium Oxide Nanotube Electrodes for Highly Sensitive and Prolonged Intracellular Measurement of Action Potentials

    PubMed Central

    Lin, Ziliang Carter; Xie, Chong; Osakada, Yasuko; Cui, Yi; Cui, Bianxiao

    2014-01-01

    Intracellular recording of action potentials is important to understand electrically-excitable cells. Recently, vertical nanoelectrodes have been developed to achieve highly sensitive, minimally invasive, and large scale intracellular recording. It has been demonstrated that the vertical geometry is crucial for the enhanced signal detection. Here we develop nanoelectrodes made up of nanotubes of iridium oxide. When cardiomyocytes are cultured upon those nanotubes, the cell membrane not only wraps around the vertical tubes but also protrudes deep into the hollow center. We show that this geometry enhances cell-electrode coupling and results in measuring much larger intracellular action potentials. The nanotube electrodes afford much longer intracellular access and are minimally invasive, making it possible to achieve stable recording up to an hour in a single session and more than 8 days of consecutive daily recording. This study suggests that the electrode performance can be significantly improved by optimizing the electrode geometry. PMID:24487777

  1. Toxicity and T₂-Weighted Magnetic Resonance Imaging Potentials of Holmium Oxide Nanoparticles.

    PubMed

    Atabaev, Timur Sh; Shin, Yong Cheol; Song, Su-Jin; Han, Dong-Wook; Hong, Nguyen Hoa

    2017-08-07

    In recent years, paramagnetic nanoparticles (NPs) have been widely used for magnetic resonance imaging (MRI). This paper reports the fabrication and toxicity evaluation of polyethylene glycol (PEG)-functionalized holmium oxide (Ho₂O₃) NPs for potential T₂-weighted MRI applications. Various characterization techniques were used to examine the morphology, structure and chemical properties of the prepared PEG-Ho₂O₃ NPs. MRI relaxivity measurements revealed that PEG-Ho₂O₃ NPs could generate a strong negative contrast in T₂-weighted MRI. The pilot cytotoxicity experiments showed that the prepared PEG-Ho₂O₃ NPs are biocompatible at concentrations less than 16 μg/mL. Overall, the prepared PEG-Ho₂O₃ NPs have potential applications for T₂-weighted MRI imaging.

  2. Oxidative stress: a potential link between emotional wellbeing and immune response.

    PubMed

    Salim, Samina

    2016-08-01

    Emotional wellbeing is central to normal health and good living. Persistent psychological stress often disrupts emotional wellbeing and triggers onset of neuropsychiatric ailments. An integrated, multisystemic stress response involving neuroinflammatory, neuroendocrine and metabolic cascades seem to have some causative links. Of particular interest are the neuroinflammatory processes. Psychological stress has been suggested to negatively affect normal functioning of the immune system contributing to the pathophysiology of some neuropsychiatric conditions. Thus examination of the interaction between the immune system and the central nervous system is likely to reveal molecular targets critical for development of potential therapeutic and preventive measures. This review is a summarized discussion of evidence linking impact of psychological stress on the immune system, with a particular emphasis on oxidative stress mechanisms by which mental stress potentially impacts immune function leading to activation of multiple cascades resulting in subsequent manifestation of psychiatric symptomologies.

  3. Chapter A6. Section 6.5. Reduction-Oxidation Potential (Electrode Method)

    USGS Publications Warehouse

    Nordstrom, Darrell Kirk; Wilde, Franceska D.

    2005-01-01

    Reduction-oxidation (redox) potential--also referred to as Eh--is a measure of the equilibrium potential, relative to the standard hydrogen electrode, developed at the interface between a noble metal electrode and an aqueous solution containing electroactive chemical species. Measurements of Eh are used to evaluate geochemical speciation models, and Eh data can provide insights on the evolution and status of water chemistry in an aqueous system. Nevertheless, the measurement is fraught with inherent interferences and limitations that must be understood and considered to determine applicability to the aqueous system being studied. For this reason, Eh determination is not one of the field parameters routinely measured by the U.S. Geological Survey (USGS). This section of the National Field Manual (NFM) describes the equipment and procedures needed to measure Eh in water using a platinum electrode. Guidance as to the limitations and interpretation of Eh measurement also is included.

  4. Prostaglandin E2 potentiates interferon-γ-induced nitric oxide production in cultured rat microglia.

    PubMed

    Nagano, Takayuki; Nishiyama, Ryo; Sanada, Ayaka; Mutaguchi, Yukiko; Ioku, Anna; Umeki, Hirohisa; Kishimoto, Satoshi; Yamanaka, Daisuke; Kimura, Shinya H; Takemura, Motohiko

    2017-02-01

    Prostaglandin E2 (PGE2 ) plays crucial roles in managing microglial activation through the prostanoid EP2 receptor, a PGE2 receptor subtype. In this study, we report that PGE2 enhances interferon-γ (IFN-γ)-induced nitric oxide production in microglia. IFN-γ increased the release of nitrite, a metabolite of nitric oxide, which was augmented by PGE2 , although PGE2 by itself slightly affects nitrite release. The potentiating effect of PGE2 was positively associated with increased expression of inducible nitric oxide synthase. In contrast to nitrite release induced by IFN-γ, lipopolysaccharide-induced nitrite release was not affected by PGE2 . An EP2 agonist, ONO-AE1-259-01 also augmented IFN-γ-induced nitrite release, while an EP1 agonist, ONO-DI-004, an EP3 agonist, ONO-AE-248, or an EP4 agonist, ONO-AE1-329, did not. In addition, the potentiating effect of PGE2 was inhibited by an EP2 antagonist, PF-04418948, but not by an EP1 antagonist, ONO-8713, an EP3 antagonist, ONO-AE3-240, or an EP4 antagonist, ONO-AE3-208, at 10(-6)  M. Among the EP agonists, ONO-AE1-259-01 alone was able to accumulate cyclic adenosine monophosphate (AMP), and among the EP antagonists, PF-04418948 was the only one able to inhibit PGE2 -increased intracellular cyclic AMP accumulation. On the other hand, IFN-γ promoted phosphorylation of signal transducer and activator of transcription 1, which was not affected by PGE2 . Furthermore, other prostanoid receptor agonists, PGD2 , PGF2α , iloprost, and U-46119, slightly affected IFN-γ-induced nitrite release. These results indicate that PGE2 potentiates IFN-γ-induced nitric oxide production in microglia through the EP2 receptor, which may shed light on one of the pro-inflammatory aspects of PGE2 . © 2016 International Society for Neurochemistry.

  5. Arsenite oxidizing multiple metal resistant bacteria isolated from industrial effluent: their potential use in wastewater treatment.

    PubMed

    Naureen, Ayesha; Rehman, Abdul

    2016-08-01

    Arsenite oxidizing bacteria, isolated from industrial wastewater, showed high resistance against arsenite (40 mM) and other heavy metals (10 mM Pb; 8 mM Cd; 6 mM Cr; 10 mM Cu and 26.6 mM As(5+)). Bacterial isolates were characterized, on the basis of morphological, biochemical and 16S rRNA ribotyping, as Bacillus cereus (1.1S) and Acinetobacter junii (1.3S). The optimum temperature and pH for the growth of both strains were found to be 37 °C and 7. Both the strains showed maximum growth after 24 h of incubation. The predominant form of arsenite oxidase was extracellular in B. cereus while in A. junii both types of activities, intracellular and extracellular, were found. The extracellular aresenite oxidase activity was found to be 730 and 750 µM/m for B. cereus and A. junii, respectively. The arsenite oxidase from both bacterial strains showed maximum activity at 37 °C, pH 7 and enhanced in the presence of Zn(2+). The presence of two protein bands with molecular weight of approximately 70 and 14 kDa in the presence of arsenic points out a possible role in arsenite oxidation. Arsenite oxidation potential of B. cereus and A. junii was determined up to 92 and 88 % in industrial wastewater after 6 days of incubation. The bacterial treated wastewater improved the growth of Vigna radiata as compared to the untreated wastewater. It indicates that these bacterial strains may find some potential applications in wastewater treatment systems to transform toxic arsenite into less toxic form, arsenate.

  6. Surface-potential dependence of interface-state passivation in metal-tunnel-oxide-silicon diodes

    NASA Astrophysics Data System (ADS)

    Andersson, M. O.; Lundgren, A.; Lundgren, P.

    1994-10-01

    Interface-state passivation during dc biased postmetallization annealing at ~350 °C was studied in very thin oxide (~31 Å) metal-tunnel-oxide-silicon structures. The gate metal was aluminum and the substrate was <111> oriented and of p type. Capacitance-voltage and tunnel-current-voltage measurements were used after the anneals to monitor the passivation of interface states. It was found that the passivation process of the initially present interface states is directly dependent on the surface potential but not on the average oxide electric field or the tunnel current. A negative gate voltage increases the passivation rate, whereas a positive gate voltage decreases it as compared to unbiased annealing. The interface states bear significant resemblances to Pb centers, which are dangling bonds on trivalently bonded Si atoms at the interface. The present observations are found to agree well with the theoretical calculations by Edwards [Phys. Rev. B 44, 1832 (1991)] on the surface-potential dependence of the passivation of Pb centers by molecular hydrogen. Furthermore, we report on the impact of biased annealing on the tunnel current and the flatband voltage and also on the behavior of electrically stressed devices during biased annealing. The beneficial effect of a negatively biased annealing makes it possible to find an optimum time and voltage, roughly 1000 s at a gate voltage of -1.2 V in our case, for simultaneously minimizing the dc tunnel current, flatband voltage shifts, and the density of fast interface states in these diodes. None of the passivation events was found to be promoted by annealing in a 10% H2/Ar ambient compared to annealing in an N2 ambient.

  7. Potentiation of osteoclast bone-resorption activity by inhibition of nitric oxide synthase.

    PubMed Central

    Kasten, T P; Collin-Osdoby, P; Patel, N; Osdoby, P; Krukowski, M; Misko, T P; Settle, S L; Currie, M G; Nickols, G A

    1994-01-01

    We have examined the effects of modulating nitric oxide (NO) levels on osteoclast-mediated bone resorption in vitro and the effects of nitric oxide synthase (NOS) inhibitors on bone mineral density in vivo. Diaphorase-based histochemical staining for NOS activity of bone sections or highly enriched osteoclast cultures suggested that osteoclasts exhibit substantial NOS activity that may account for basal NO production. Chicken osteoclasts were cultured for 36 hr on bovine bone slices in the presence or absence of the NO-generating agent sodium nitroprusside or the NOS inhibitors N-nitro-L-arginine methyl ester and aminoguanidine. Nitroprusside markedly decreased the number of bone pits and the average pit area in comparison with control cultures. On the other hand, NOS inhibition by N-nitro-L-arginine methyl ester or aminoguanidine dramatically increased the number of bone pits and the average resorption area per pit. In a model of osteoporosis, aminoguanidine potentiated the loss of bone mineral density in ovariectomized rats. Aminoguanidine also caused a loss of bone mineral density in the sham-operated rats. Inhibition of NOS activity in vitro and in vivo resulted in an apparent potentiation of osteoclast activity. These findings suggest that endogenous NO production in osteoclast cultures may regulate resorption activity. The modulation of NOS and NO levels by cells within the bone microenvironment may be a sensitive mechanism for local control of osteoclast bone resorption. Images PMID:7513424

  8. Bio-therapeutic Potential and Cytotoxicity Assessment of Pectin-Mediated Synthesized Nanostructured Cerium Oxide.

    PubMed

    Patil, Sandeep N; Paradeshi, Jayasinh S; Chaudhari, Prapti B; Mishra, Satyendra J; Chaudhari, Bhushan L

    2016-10-01

    In the present studies, renewable and nontoxic biopolymer, pectin, was extracted from Indian red pomelo fruit peels and used for the synthesis of cerium oxide nanoparticles (CeO2-NPs) having bio-therapeutic potential. The structural information of extracted pectin was investigated by FTIR and NMR spectroscopic techniques. Physicochemical characteristics of this pectin suggested its application in the synthesis of metal oxide nanoparticles. Using this pectin as a template, CeO2-NPs were synthesized by simple, one step and eco-friendly approach. The UV-Vis spectrum of synthesized CeO2-NPs exhibited a characteristic absorption peak at wavelength 345 nm, which can be assigned to its intrinsic band gap (3.59 eV) absorption. Photoluminescence measurements of CeO2-NPs revealed that the broad emission was composed of seven different bands. FTIR analysis ensured involvement of pectin in the formation and stabilization of CeO2-NPs. FT-Raman spectra showed a sharp Raman active mode peak at 461.8 cm(-1) due to a symmetrical stretching mode of Ce-O vibration. DLS, FESEM, EDX, and XRD analysis showed that the CeO2-NPs prepared were polydispersed, spherical shaped with a cubic fluorite structure and average particle size ≤40 nm. These CeO2-NPs displayed broad spectrum antimicrobial activity, antioxidant potential, and non-cytotoxic nature.

  9. Oxygen distribution and potential ammonia oxidation in floating, liquid manure crusts.

    PubMed

    Nielsen, Daniel Aa; Nielsen, Lars P; Schramm, Andreas; Revsbech, Niels P

    2010-01-01

    Floating, organic crusts on liquid manure, stored as a result of animal production, reduce emission of ammonia (NH3) and other volatile compounds during storage. The occurrence of NO2- and NO3- in the crusts indicate the presence of actively metabolizing NH3-oxidizing bacteria (AOB) which may be partly responsible for this mitigation effect. Six manure tanks with organic covers (straw and natural) were surveyed to investigate the prevalence and potential activity ofAOB and its dependence on the O2 availability in the crust matrix as studied by electrochemical profiling. Oxygen penetration varied from <1 mm in young, poorly developed natural crusts and old straw crusts, to several centimeters in the old natural crusts. The AOB were ubiquitously present in all crusts investigated, but nitrifying activity could only be detected in old natural crusts and young straw crust with high O2 availability. In old natural crusts, total potential NH3 oxidation rates were similar to reported fluxes of NH3 from slurry without surface crust. These results indicate that old, natural surface crusts may develop into a porous matrix with high O2 availability that harbors an active population of aerobic microorganisms, including AOB. The microbial activity may thus contribute to a considerable reduction of ammonia emissions from slurry tanks with well-developed crusts.

  10. Enrichment processes of arsenic in oxidic sedimentary rocks - from geochemical and genetic characterization to potential mobility.

    PubMed

    Banning, Andre; Rüde, Thomas R

    2010-11-01

    Sedimentary marine iron ores of Jurassic age and Tertiary marine sandy sediments containing iron hydroxides concretions have been sampled from boreholes and outcrops in two study areas in Germany to examine iron and arsenic accumulation processes. Samples were analyzed for bulk rock geochemistry (INAA/ICP-OES), quantitative mineralogy (XRD with Rietveld analysis), element distribution (electron microprobe) and arsenic fractionation (sequential extraction). Bulk Jurassic ores contain an average arsenic content of 123 μg g(-1) hosted in mainly goethite ooids which slowly formed in times of condensed sedimentation. Enrichment occurred syndepositionally and is therefore characterized as primary. Iron concretions in Tertiary sediments mainly consist of goethite and yield arsenic up to 1860 μg g(-1). The accumulation process is secondary as it took place in the course of oxidation of the originally reduced marine sediments under terrestrial conditions, leading to element redistribution and local enrichment in the near-surface part. The scale of enrichment was assessed calculating Enrichment Factors, indicating that arsenic accumulation was favoured over other potential contaminants. In spite of higher bulk arsenic contents in the oxidic rocks, the mainly pyrite-hosted As pool within the reduced deeper part of the Tertiary sediments is shown to have a higher potential for remobilization and creation of elevated arsenic concentrations in groundwater. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Three-Dimensional Localization of the α and β Subunits and of the II-III Loop in the Skeletal Muscle L-type Ca2+ Channel*

    PubMed Central

    Szpyt, John; Lorenzon, Nancy; Perez, Claudio F.; Norris, Ethan; Allen, Paul D.; Beam, Kurt G.; Samsó, Montserrat

    2012-01-01

    The L-type Ca2+ channel (dihydropyridine receptor (DHPR) in skeletal muscle acts as the voltage sensor for excitation-contraction coupling. To better resolve the spatial organization of the DHPR subunits (α1s or CaV1.1, α2, β1a, δ1, and γ), we created transgenic mice expressing a recombinant β1a subunit with YFP and a biotin acceptor domain attached to its N- and C- termini, respectively. DHPR complexes were purified from skeletal muscle, negatively stained, imaged by electron microscopy, and subjected to single-particle image analysis. The resulting 19.1-Å resolution, three-dimensional reconstruction shows a main body of 17 × 11 × 8 nm with five corners along its perimeter. Two protrusions emerge from either face of the main body: the larger one attributed to the α2-δ1 subunit that forms a flexible hook-shaped feature and a smaller protrusion on the opposite side that corresponds to the II-III loop of CaV1.1 as revealed by antibody labeling. Novel features discernible in the electron density accommodate the atomic coordinates of a voltage-gated sodium channel and of the β subunit in a single docking possibility that defines the α1-β interaction. The β subunit appears more closely associated to the membrane than expected, which may better account for both its role in localizing the α1s subunit to the membrane and its suggested role in excitation-contraction coupling. PMID:23118233

  12. Fibroblast Growth Factor 2-A Predictor of Outcome for Patients Irradiated for Stage II-III Non-Small-Cell Lung Cancer

    SciTech Connect

    Rades, Dirk; Setter, Cornelia; Dahl, Olav; Schild, Steven E.; Noack, Frank

    2012-01-01

    Purpose: The prognostic value of the tumor cell expression of the fibroblast growth factor 2 (FGF-2) in patients with non-small-cell lung cancer (NSCLC) is unclear. The present study investigated the effect of tumor cell expression of FGF-2 on the outcome of 60 patients irradiated for Stage II-III NSCLC. Methods and Materials: The effect of FGF-2 expression and 13 additional factors on locoregional control (LRC), metastasis-free survival (MFS), and overall survival (OS) were retrospectively evaluated. These additional factors included age, gender, Karnofsky performance status, histologic type, histologic grade, T and N category, American Joint Committee on Cancer stage, surgery, chemotherapy, pack-years, smoking during radiotherapy, and hemoglobin during radiotherapy. Locoregional failure was identified by endoscopy or computed tomography. Univariate analyses were performed with the Kaplan-Meier method and the Wilcoxon test and multivariate analyses with the Cox proportional hazard model. Results: On univariate analysis, improved LRC was associated with surgery (p = .017), greater hemoglobin levels (p = .036), and FGF-2 negativity (p <.001). On multivariate analysis of LRC, surgery (relative risk [RR], 2.44; p = .037), and FGF-2 expression (RR, 5.06; p <.001) maintained significance. On univariate analysis, improved MFS was associated with squamous cell carcinoma (p = .020), greater hemoglobin levels (p = .007), and FGF-2 negativity (p = .001). On multivariate analysis of MFS, the hemoglobin levels (RR, 2.65; p = .019) and FGF-2 expression (RR, 3.05; p = .004) were significant. On univariate analysis, improved OS was associated with a lower N category (p = .048), greater hemoglobin levels (p <.001), and FGF-2 negativity (p <.001). On multivariate analysis of OS, greater hemoglobin levels (RR, 4.62; p = .002) and FGF-2 expression (RR, 3.25; p = .002) maintained significance. Conclusions: Tumor cell expression of FGF-2 appeared to be an independent negative predictor

  13. Hospital Characteristics Associated with Stage II/III Rectal Cancer Guideline Concordant Care: Analysis of Surveillance, Epidemiology and End Results-Medicare Data.

    PubMed

    Charlton, Mary E; Hrabe, Jennifer E; Wright, Kara B; Schlichting, Jennifer A; McDowell, Bradley D; Halfdanarson, Thorvardur R; Lin, Chi; Stitzenberg, Karyn B; Cromwell, John W

    2016-05-01

    Evidence suggests that high-volume facilities achieve better rectal cancer outcomes. Logistic regression was used to evaluate association of facility type with treatment after adjusting for patient demographics, stage, and comorbidities. SEER-Medicare beneficiaries who were diagnosed with stage II/III rectal adenocarcinoma at age ≥66 years from 2005 to 2009 and had Parts A/B Medicare coverage for ≥1 year prediagnosis and postdiagnosis plus a claim for cancer-directed surgery were included. Institutions were classified according to National Cancer Institute (NCI) designation, presence of residency program, or medical school affiliation. Two thousand three hundred subjects (average age = 75) met the criteria. Greater proportions of those treated at NCI-designated facilities received transrectal ultrasound (TRUS) or magnetic resonance imaging (MRI)-pelvis (62.1 vs. 29.9 %), neoadjuvant chemotherapy (63.9 vs. 41.8 %), and neoadjuvant radiation (70.8 vs. 46.3 %), all p < 0.0001. On multivariate analysis, odds ratios (95 % confidence intervals) for receiving TRUS or MRI, neoadjuvant chemotherapy, or neoadjuvant radiation among beneficiaries treated at NCI-designated facilities were 3.51 (2.60-4.73), 2.32 (1.71-3.16), and 2.66 (1.93-3.67), respectively. Results by residency and medical school affiliation were similar in direction to NCI designation. Those treated at hospitals with an NCI designation, residency program, or medical school affiliation received more guideline-concordant care. Initiatives involving provider education and virtual tumor boards may improve care.

  14. Oral 5-aminolevulinic acid mediated photodynamic diagnosis using fluorescence cystoscopy for non-muscle-invasive bladder cancer: A randomized, double-blind, multicentre phase II/III study.

    PubMed

    Inoue, Keiji; Anai, Satoshi; Fujimoto, Kiyohide; Hirao, Yoshihiko; Furuse, Hiroshi; Kai, Fumitake; Ozono, Seiichiro; Hara, Takahiko; Matsuyama, Hideyasu; Oyama, Masafumi; Ueno, Munehisa; Fukuhara, Hideo; Narukawa, Mamoru; Shuin, Taro

    2015-06-01

    Photodynamic diagnosis (PDD) of non-muscle-invasive bladder cancer (NMIBC) following transurethral administration of a hexalated form of 5-aminolevulinic acid (5-ALA), 5-ALA hexyl ester, is widely performed in Western countries. In this study, effectiveness and safety of the oral administration of 5-ALA is assessed in a phase II/III study of PDD for NMIBC in comparison to those of conventional white-light endoscopic diagnosis. Patients with NMIBC were allocated to two groups that were orally administered 10 and 20 mg/kg of 5-ALA under the double-blind condition. Effectiveness was evaluated by setting the primary endpoint to sensitivity. Safety was also analyzed. Moreover, clinically recommended doses of 5-ALA was also investigated as an investigator-initiated multicenter cooperative clinical trial in which five medical institutions participated. All 62 enrolled patients completed the clinical trial. The sensitivities of PDD were higher (84.4 and 75.8% in the 10 and 20 m g/kg-groups, respectively) than those of conventional endoscopic diagnosis (67.5 and 47.6%, respectively) (p = 0.014 and p < 0.001, respectively). Five episodes of serious adverse events developed in four patients; whereas a causal relationship with the investigational agent was ruled out in all episodes. This investigator-initiated clinical trial confirmed the effectiveness and safety of PDD for NMIBC following oral administration of 5-ALA. Both doses of 5-ALA may be clinically applicable; however, the rate of detecting tumors only by PDD was higher in the 20 mg/kg-group suggesting that this dose would be more useful. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Clinical Effectiveness of Intravenous Exenatide Infusion in Perioperative Glycemic Control after Coronary Artery Bypass Graft Surgery: A Phase II/III Randomized Trial.

    PubMed

    Besch, Guillaume; Perrotti, Andrea; Mauny, Frederic; Puyraveau, Marc; Baltres, Maude; Flicoteaux, Guillaume; Salomon du Mont, Lucie; Barrucand, Benoit; Samain, Emmanuel; Chocron, Sidney; Pili-Floury, Sebastien

    2017-08-18

    We aimed to assess the clinical effectiveness of intravenous exenatide compared to insulin in perioperative blood glucose control in coronary artery bypass grafting surgery patients. Patients more than 18 yr old admitted for elective coronary artery bypass grafting were included in a phase II/III nonblinded randomized superiority trial. Current insulin use and creatinine clearance of less than 60 ml/min were exclusion criteria. Two groups were compared: the exenatide group, receiving exenatide (1-h bolus of 0.05 µg/min followed by a constant infusion of 0.025 µg/min), and the control group, receiving insulin therapy. The blood glucose target range was 100 to 139 mg/dl. The primary outcome was the proportion of patients who spent at least 50% of the study period within the target range. The consumption of insulin (Cinsulin) and the time to start insulin (Tinsulin) were compared between the two groups. In total, 53 and 51 patients were included and analyzed in the exenatide and control groups, respectively (age: 70 ± 9 vs. 68 ± 11 yr; diabetes mellitus: 12 [23%] vs. 10 [20%]). The primary outcome was observed in 38 (72%) patients in the exenatide group and in 41 (80%) patients in the control group (odds ratio [95% CI] = 0.85 [0.34 to 2.11]; P = 0.30). Cinsulin was significantly lower (60 [40 to 80] vs. 92 [63 to 121] U, P < 0.001), and Tinsulin was significantly longer (12 [7 to 16] vs. 7 [5 to 10] h, P = 0.02) in the exenatide group. Exenatide alone at the dose used was not enough to achieve adequate blood glucose control in coronary artery bypass grafting patients, but it reduces overall consumption of insulin and increases the time to initiation of insulin.

  16. Manganese(II,III) Oxyborate, Mn 2OBO 3: A Distorted Homometallic Warwickite—Synthesis, Crystal Structure, Band Calculations, and Magnetic Susceptibility

    NASA Astrophysics Data System (ADS)

    Norrestam, R.; Kritikos, M.; Sjödin, A.

    1995-02-01

    The manganese(II,III) oxyborate with the composition Mn2OBO3 has been synthesized by high-temperature techniques. X-ray studies show that crystals of the specimen, grown with borax as flux, are monoclinic, with space group P21/n, = 9.2866(7), b = 9.5333(10), c = 3.2438(3) Å, and β = 90.757(7)°. A model of the crystal structure has been refined with the 2064 most significant (l ≥ 5 · σ1) X-ray reflections with sin(θ)/λ ≤ 1.08 Å-1 to R = 0.40. The structure of Mn2OBO3 can be considered to be a distorted modification of the orthorhombic warwickite structure. The distortions, apparently caused by Jahn-Teller effects induced by the Mn3+ ions, remove the mirror symmetry of the parent undistorted warwickite. As a consequence, the space group symmetry is lowered from Pnam to one of its subgroups, P21/n. The structural results as well as the measured magnetic susceptibilities indicate high-spin manganese ions. The magnetic susceptibilities in the temperature region 110-300 K follow the Curie-Weiss law. The Weiss constant of -132(1) K indicates an antiferromagnetic ordering at low temperature. The bond distances and calculated bond valence sums indicate that the trivalent manganese ions are located in the two inner columns of the four-octahedra-wide walls. This metal charge distribution is supported by extended Hückel band calculations on some homometallic warwickites. The difference in metal coordination around one of the borate oxygen atoms is reflected by a significant deviation of the borate group geometry from the ideal trigonal symmetry.

  17. Rab27a GTPase modulates L-type Ca2+ channel function via interaction with the II-III linker of CaV1.3 subunit.

    PubMed

    Reichhart, Nadine; Markowski, Magdalena; Ishiyama, Shimpei; Wagner, Andrea; Crespo-Garcia, Sergio; Schorb, Talitha; Ramalho, José S; Milenkovic, Vladimir M; Föckler, Renate; Seabra, Miguel C; Strauß, Olaf

    2015-11-01

    In a variety of cells, secretory processes require the activation of both Rab27a and L-type channels of the Ca(V)1.3 subtype. In the retinal pigment epithelium (RPE), Rab27a and Ca(V)1.3 channels regulate growth-factor secretion towards its basolateral side. Analysis of murine retina sections revealed a co-localization of both Rab27a and Ca(V)1.3 at the basolateral membrane of the RPE. Heterologously expressed Ca(V)1.3/β3/α2δ1 channels showed negatively shifted voltage-dependence and decreased current density of about 70% when co-expressed with Rab27a. However, co-localization analysis using α(5)β(1) integrin as a membrane marker revealed that Rab27a co-expression reduced the surface expression of Ca(V)1.3 only about 10%. Physical binding of heterologously expressed Rab27a with Ca(V)1.3 channels was shown by co-localization in immunocytochemistry as well as co-immunoprecipitation which was abolished after deletion of a MyRIP-homologous amino acid sequence at the II-III linker of the Ca(V)1.3 subunit. Rab27a over-expression in ARPE-19 cells positively shifted the voltage dependence, decreased current density of endogenous Ca(V)1.3 channels and reduced VEGF-A secretion. We show the first evidence of a direct functional modulation of an ion channel by Rab27a suggesting a new mechanism of Rab and ion channel interaction in the control of VEGF-A secretion in the RPE.

  18. Safety and immunogenicity of Bio Pox™, a live varicella vaccine (Oka strain) in Indian children: A comparative multicentric, randomized phase II/III clinical trial.

    PubMed

    Dubey, Anand Prakash; Faridi, Mohammad Moonis Akbar; Mitra, Monjori; Kaur, Iqbal Rajinder; Dabas, Aashima; Choudhury, Jaydeep; Mukherjee, Mallar; Mishra, Devendra

    2017-09-02

    Varicella or chickenpox is a highly contagious disease with a high secondary attack rate. Almost 30% of Indian adolescents lack protective antibodies against varicella, emphasizing the need of routine varicella immunization. The Oka VZV is a well-established, safe and efficacious vaccine strain that is highly immunogenic and produces lifelong protective immunity. The present multicentric, open label, randomized, controlled Phase II/III study, compared the Bio Pox™ (indigenous investigational vaccine) with a licensed vaccine, Varivax™ ([a])([a]) Please note that this article refers to the product named VARIVAX as manufactured by Changchun Keygen Biological Products Ltd., China and marketed in India by VHB Life Sciences Limited, Mumbai, and not the product VARIVAX® owned by Merck Sharp & Dohme Corp., Rahway, New Jersey, USA. Merck Sharp & Dohme Corp. have asked us to make clear that the product manufactured by Changchun Keygen Biological Products Ltd. is unrelated to and is not sponsored, endorsed or otherwise authorised by Merck Sharp & Dohme Corp. , for its safety and immunogenicity profile in 252 healthy subjects in the age group of 1-12 y (cohort I: 6-12 years, II:1-6 years) in 3 tertiary medical institutions. Antibodies were measured by VZV Glycoprotein Enzyme Linked Immunoassay (IgG ELISA) kit. Seroconversion percentage in children having pre-vaccination anti VZV IgG titer <10 mIU/mL (< 5 gp ELISA units/mL) were 80% for Bio Pox™ and 77% for Varivax™ (p = 0.692). The seroconversion rate in the group receiving Bio Pox™ was non-inferior to the group that received Varivax™. There were mild local reactions for both the vaccines; none of the patient had fever or required hospitalization or medication. The Bio Pox™ was found to be safe and immunogenic in children against VZV infection.

  19. [Emergency closed reduction and percutaneous Kirschner wire fixation for treatment of Gartland type II-III supracondylar fractures of the humerus in children].

    PubMed

    Fan, Jiang-rong; Xu, Yi-wen; Zheng, Yong; You, Jing-yang

    2015-05-01

    To analyze the clinical effect and related risk factors of Gartland type II-III supracondylar fractures of humerus in children in the emergency closed reduction and percutaneous Kirschner wire fixation. From January 2008 to June 2013,112 children of Gartland type II to III supracondylar humeral fractures were treated in children in emergency closed reduction and percutaneous K-wire fixation, including 72 males and 40 females with an average age of 6.2 years old ranging from 2 to 11 years old. Among them,74 cases were in Gartland type II fractures,38 cases were in type III; The duration from injury to surgery time was 2.5 to 8 hours (averaged 4.6 hours). Elbow cast was applied after operation with the elbow extended of 100 degrees for 4 to 6 weeks, then the gypsum and Kirschner wires were removed. All patients were follow-up from 6 to 60 months (averaged 12 months). All fractures reached clinical healing. The final follow-up was assessed by Flynn criteria, the result was excellent in 86 cases, good in 23 cases, general in 3 cases, excellent and good rate was 97.3%. Three patients had mild cubitus varus deformity without orthopedic treatment. No pin tract infections, iatrogenic ulnar nerve injury, compartment syndrome, and complications such as Volkmann ischemic contracture occurred. Closed reduction and percutaneous Kirschner wire fixation had advantages of exact reduction, firm fixation, fewer complications ,less pain in children undergoing emergency surgery, and.high success rate, so it is a safe and efficient treatment for humeral supracondylar fracture in children.

  20. Mastectomy With Immediate Expander-Implant Reconstruction, Adjuvant Chemotherapy, and Radiation for Stage II-III Breast Cancer: Treatment Intervals and Clinical Outcomes

    SciTech Connect

    Wright, Jean L.; Cordeiro, Peter G.; Ben-Porat, Leah; Van Zee, Kimberly J.; Hudis, Clifford; Beal, Kathryn; McCormick, Beryl

    2008-01-01

    Purpose: To determine intervals between surgery and adjuvant chemotherapy and radiation in patients treated with mastectomy with immediate expander-implant reconstruction, and to evaluate locoregional and distant control and overall survival in these patients. Methods and Materials: Between May 1996 and March 2004, 104 patients with Stage II-III breast cancer were routinely treated at our institution under the following algorithm: (1) definitive mastectomy with axillary lymph node dissection and immediate tissue expander placement, (2) tissue expansion during chemotherapy, (3) exchange of tissue expander for permanent implant, (4) radiation. Patient, disease, and treatment characteristics and clinical outcomes were retrospectively evaluated. Results: Median age was 45 years. Twenty-six percent of patients were Stage II and 74% Stage III. All received adjuvant chemotherapy. Estrogen receptor staining was positive in 77%, and 78% received hormone therapy. Radiation was delivered to the chest wall with daily 0.5-cm bolus and to the supraclavicular fossa. Median dose was 5040 cGy. Median interval from surgery to chemotherapy was 5 weeks, from completion of chemotherapy to exchange 4 weeks, and from exchange to radiation 4 weeks. Median interval from completion of chemotherapy to start of radiation was 8 weeks. Median follow-up was 64 months from date of mastectomy. The 5-year rate for locoregional disease control was 100%, for distant metastasis-free survival 90%, and for overall survival 96%. Conclusions: Mastectomy with immediate expander-implant reconstruction, adjuvant chemotherapy, and radiation results in a median interval of 8 weeks from completion of chemotherapy to initiation of radiation and seems to be associated with acceptable 5-year locoregional control, distant metastasis-free survival, and overall survival.

  1. Three-dimensional localization of the α and β subunits and of the II-III loop in the skeletal muscle L-type Ca2+ channel.

    PubMed

    Szpyt, John; Lorenzon, Nancy; Perez, Claudio F; Norris, Ethan; Allen, Paul D; Beam, Kurt G; Samsó, Montserrat

    2012-12-21

    The L-type Ca(2+) channel (dihydropyridine receptor (DHPR) in skeletal muscle acts as the voltage sensor for excitation-contraction coupling. To better resolve the spatial organization of the DHPR subunits (α(1s) or Ca(V)1.1, α(2), β(1a), δ1, and γ), we created transgenic mice expressing a recombinant β(1a) subunit with YFP and a biotin acceptor domain attached to its N- and C- termini, respectively. DHPR complexes were purified from skeletal muscle, negatively stained, imaged by electron microscopy, and subjected to single-particle image analysis. The resulting 19.1-Å resolution, three-dimensional reconstruction shows a main body of 17 × 11 × 8 nm with five corners along its perimeter. Two protrusions emerge from either face of the main body: the larger one attributed to the α(2)-δ1 subunit that forms a flexible hook-shaped feature and a smaller protrusion on the opposite side that corresponds to the II-III loop of Ca(V)1.1 as revealed by antibody labeling. Novel features discernible in the electron density accommodate the atomic coordinates of a voltage-gated sodium channel and of the β subunit in a single docking possibility that defines the α1-β interaction. The β subunit appears more closely associated to the membrane than expected, which may better account for both its role in localizing the α(1s) subunit to the membrane and its suggested role in excitation-contraction coupling.

  2. Solar-mediated thermo-electrochemical oxidation of sodium dodecyl benzene sulfonate by modulating the effective oxidation potential and pathway for green remediation of wastewater

    PubMed Central

    Gu, Di; Gao, Simeng; Jiang, TingTing; Wang, Baohui

    2017-01-01

    To match the relentless pursuit of three research hot points - efficient solar utilization, green and sustainable remediation of wastewater and advanced oxidation processes, solar-mediated thermo-electrochemical oxidation of surfactant was proposed and developed for green remediation of surfactant wastewater. The solar thermal electrochemical process (STEP), fully driven with solar energy to electric energy and heat and without an input of other energy, sustainably serves as efficient thermo-electrochemical oxidation of surfactant, exemplified by SDBS, in wastewater with the synergistic production of hydrogen. The electrooxidation-resistant surfactant is thermo-electrochemically oxidized to CO2 while hydrogen gas is generated by lowing effective oxidation potential and suppressing the oxidation activation energy originated from the combination of thermochemical and electrochemical effect. A clear conclusion on the mechanism of SDBS degradation can be proposed and discussed based on the theoretical analysis of electrochemical potential by quantum chemical method and experimental analysis of the CV, TG, GC, FT-IR, UV-vis, Fluorescence spectra and TOC. The degradation data provide a pilot for the treatment of SDBS wastewater that appears to occur via desulfonation followed by aromatic-ring opening. The solar thermal utilization that can initiate the desulfonation and activation of SDBS becomes one key step in the degradation process. PMID:28294180

  3. Solar-mediated thermo-electrochemical oxidation of sodium dodecyl benzene sulfonate by modulating the effective oxidation potential and pathway for green remediation of wastewater

    NASA Astrophysics Data System (ADS)

    Gu, Di; Gao, Simeng; Jiang, Tingting; Wang, Baohui

    2017-03-01

    To match the relentless pursuit of three research hot points - efficient solar utilization, green and sustainable remediation of wastewater and advanced oxidation processes, solar-mediated thermo-electrochemical oxidation of surfactant was proposed and developed for green remediation of surfactant wastewater. The solar thermal electrochemical process (STEP), fully driven with solar energy to electric energy and heat and without an input of other energy, sustainably serves as efficient thermo-electrochemical oxidation of surfactant, exemplified by SDBS, in wastewater with the synergistic production of hydrogen. The electrooxidation-resistant surfactant is thermo-electrochemically oxidized to CO2 while hydrogen gas is generated by lowing effective oxidation potential and suppressing the oxidation activation energy originated from the combination of thermochemical and electrochemical effect. A clear conclusion on the mechanism of SDBS degradation can be proposed and discussed based on the theoretical analysis of electrochemical potential by quantum chemical method and experimental analysis of the CV, TG, GC, FT-IR, UV-vis, Fluorescence spectra and TOC. The degradation data provide a pilot for the treatment of SDBS wastewater that appears to occur via desulfonation followed by aromatic-ring opening. The solar thermal utilization that can initiate the desulfonation and activation of SDBS becomes one key step in the degradation process.

  4. Solar-mediated thermo-electrochemical oxidation of sodium dodecyl benzene sulfonate by modulating the effective oxidation potential and pathway for green remediation of wastewater.

    PubMed

    Gu, Di; Gao, Simeng; Jiang, TingTing; Wang, Baohui

    2017-03-15

    To match the relentless pursuit of three research hot points - efficient solar utilization, green and sustainable remediation of wastewater and advanced oxidation processes, solar-mediated thermo-electrochemical oxidation of surfactant was proposed and developed for green remediation of surfactant wastewater. The solar thermal electrochemical process (STEP), fully driven with solar energy to electric energy and heat and without an input of other energy, sustainably serves as efficient thermo-electrochemical oxidation of surfactant, exemplified by SDBS, in wastewater with the synergistic production of hydrogen. The electrooxidation-resistant surfactant is thermo-electrochemically oxidized to CO2 while hydrogen gas is generated by lowing effective oxidation potential and suppressing the oxidation activation energy originated from the combination of thermochemical and electrochemical effect. A clear conclusion on the mechanism of SDBS degradation can be proposed and discussed based on the theoretical analysis of electrochemical potential by quantum chemical method and experimental analysis of the CV, TG, GC, FT-IR, UV-vis, Fluorescence spectra and TOC. The degradation data provide a pilot for the treatment of SDBS wastewater that appears to occur via desulfonation followed by aromatic-ring opening. The solar thermal utilization that can initiate the desulfonation and activation of SDBS becomes one key step in the degradation process.

  5. The role of postmastectomy radiotherapy in clinically node-positive, stage II-III breast cancer patients with pathological negative nodes after neoadjuvant chemotherapy: an analysis from the NCDB

    PubMed Central

    Jiang, Shuai; Jiang, Wen; Chen, Kai; Kim, Betty Y.S.; Liu, Qiang; Jacobs, Lisa K.

    2016-01-01

    Purpose The role of postmastectomy radiotherapy (PMRT) in clinically node-positive, stage II-III breast cancer patients with pathological negative nodes (ypN0) after neoadjuvant chemotherapy (NAC) remains controversial. Methods A total of 1560 clinically node-positive, stage II-III breast cancer patients treated with NAC and mastectomy who achieved ypN0 between 1998 and 2009 in the National Cancer Database were analyzed. The effects of PMRT on overall survival (OS) for the entire cohort and multiple subgroups were evaluated. Imputation and propensity score matching were used as sensitivity analyses to minimize biases. Results Of the entire 1560 eligible patients, 903 (57.9%) received PMRT and 657 (42.1%) didn’t. At a median follow-up of 56.0 months, no statistical difference was observed for OS between two groups by univariate and multivariate analyses (P = 0.120; HR 1.571, 95% CI 0.839-2.943). On subgroup analyses, PMRT significantly improved OS in patients with clinical stage IIIB/IIIC disease, T3/T4 tumor, or residual invasive breast cancer after NAC (P < 0.05). This improvement in OS remained significant after sensitivity analyses for the propensity score-matched patients. Conclusions This study demonstrated that PMRT showed a heterogeneous effect in clinically node-positive, stage II-III breast cancer patients with ypN0 following NAC. PMRT improved OS for patients with clinical stage IIIB/IIIC disease, T3/T4 tumor, or residual invasive breast tumor after NAC. In the absence of definitive conclusions from prospective studies, including the ongoing NSABP B-51 trial, our findings may help identify specific groups of women with clinically node-positive, stage II-III breast cancers who could benefit from PMRT after NAC. PMID:26709538

  6. N-acetylcysteine as a potential strategy to attenuate the oxidative stress induced by uremic serum in the vascular system.

    PubMed

    Rodrigues, Silvia D; França, Karime C; Dallin, Fernando T; Fujihara, Clarice K; Nascimento, Aguinaldo J; Pecoits-Filho, Roberto; Nakao, Lia S

    2015-01-15

    Chronic kidney disease (CKD) progression is accompanied by systemic oxidative stress, which contributes to an increase in the risk of cardiovascular diseases (CVDs). N-acetylcysteine (NAC) is among the most studied antioxidants, but its therapeutic benefits in CKD-associated CVDs remain controversial. Here, we investigated whether NAC could inhibit the oxidative stress induced by uremia in vitro and in vivo. Endothelial and smooth muscle cells were challenged with human uremic or non-uremic sera, and the effects of a pre-treatment with 2mM NAC were evaluated. Reactive oxygen species (ROS) production, protein oxidation and total glutathione/glutathione disulfide (tGSH/GSSG) ratios were measured. Five-sixths nephrectomized or sham-operated rats were orally treated (in the drinking water) with 60 mg/kg/day NAC or not treated for 53 days. Plasma cysteine/cystine reduction potential Eh(Cyss/2Cys) was determined as a novel marker of the systemic oxidative stress. NAC inhibited all the determined oxidative stress parameters, likely by increasing the tGSH/GSSG ratio, in both cell lines exposed to uremic serum. Orally administered NAC attenuated the systemic oxidative stress in uremic rats. The present results indicate that NAC, by preventing GSH depletion in vascular cells exposed to uremic serum and by attenuating the systemic oxidative stress during CKD progression, emerges as a potential strategy to prevent the oxidative stress induced by uremic toxicity in the vascular system. Copyright © 2014. Published by Elsevier Inc.

  7. Understanding the sources and mitigation potential of nitrous oxide in agriculture

    NASA Astrophysics Data System (ADS)

    Horwath, W. R.; Zhu, X.; Doane, T. A.; Burger, M.

    2014-12-01

    More than half of the global warming potential of GHG emissions from agriculture is attributed to nitrous oxide (N2O).. Many factors control the production and release of N2O from soils. In addition to fertilizer N, soil N, moisture and carbon availability control N2O emissions. In addition, a previously overlooked factor, iron, was recently found to be the most significant factor influencing N2O production. Controlled by soil and management factors, N2O production is attributed to multiple pathways, including ammonia oxidation (AO), denitrification, and abiotic chemical reactions. Ammonia oxidation or nitrifier activity N2O production, is a well known pathway, but it significance to total N2O production is also highly debated and soil conditions influencing its production are poorly understood. Studies in a variety of crops in California strongly suggest that this pathway contributes substantially to N2O emissions. It is well established that denitrification primarily occurs under O2- limiting conditions, while N2O produced from AO is also influenced by soil O2 content, with maximum production occurring at low O2 levels (~0.5%). Since emission of N2O can arise from both AO and denitrification activities at low O2 concentrations, it is difficult to discern the importance of each pathway under various soil conditions and management. Furthermore, both the N form and concentration are determinants of nitrifier N2O production. The nitrifier denitrification pathway has been shown to dominate over nitrifier nitrification and nitrification coupled denitrification pathways. Irrigation, rainfall, and fertilization events stimulate microbial activity, including AO and denitrification that produces N2O and although limited, these events contribute to the majority of annual emissions. This uncertainty and complexity surrounding N2O production pathways has hampered the development of practices to reduce N2O emissions. As agricultural production intensifies in developing

  8. Oxidative DNA damage preventive activity and antioxidant potential of plants used in Unani system of medicine

    PubMed Central

    2010-01-01

    . wallichii and H. antidysenterica - showed moderate antioxidant activity. Finally, potentially significant oxidative DNA damage preventive activity and antioxidant activity were noted in three plant extracts: C. icosandra, R. damascena and C. scariosus. These three plant extracts showed no cytotoxic activity against U937 cells. Conclusions The 50% methanolic extracts obtained from different plant parts contained significant amounts of polyphenols with superior antioxidant activity as evidenced by the scavenging of DPPH·, ABTS·+, NO, ·OH, O2.- and ONOO-. C. icosandra, R. damascena and C. scariosus showed significant potential for preventing oxidative DNA damage and radical scavenging activity, and the G. gummifera, A. pindrow, V. wallichii, H. antidysenterica, A. pyrethrum, A. tenuifolius and O. mascula extracts showed moderate activity. The extracts of C. icosandra, R. damascena and C. scariosus showed no cytotoxicity against U937 cells. In conclusion, these routinely used Unani plants, especially C. icosandra, R. damascena and C. scariosus, which are reported to have significant activity against several human ailments, could be exploited as potential sources of natural antioxidants for plant-based pharmaceutical industries. PMID:21159207

  9. Oxidative DNA damage preventive activity and antioxidant potential of plants used in Unani system of medicine.

    PubMed

    Kalim, Mehar Darukhshan; Bhattacharyya, Dipto; Banerjee, Anindita; Chattopadhyay, Sharmila

    2010-12-16

    . pindrow, V. wallichii and H. antidysenterica - showed moderate antioxidant activity. Finally, potentially significant oxidative DNA damage preventive activity and antioxidant activity were noted in three plant extracts: C. icosandra, R. damascena and C. scariosus. These three plant extracts showed no cytotoxic activity against U937 cells. The 50% methanolic extracts obtained from different plant parts contained significant amounts of polyphenols with superior antioxidant activity as evidenced by the scavenging of DPPH(·), ABTS(·+), NO, (·)OH, O₂(·⁻) and ONOO(⁻). C. icosandra, R. damascena and C. scariosus showed significant potential for preventing oxidative DNA damage and radical scavenging activity, and the G. gummifera, A. pindrow, V. wallichii, H. antidysenterica, A. pyrethrum, A. tenuifolius and O. mascula extracts showed moderate activity. The extracts of C. icosandra, R. damascena and C. scariosus showed no cytotoxicity against U937 cells. In conclusion, these routinely used Unani plants, especially C. icosandra, R. damascena and C. scariosus, which are reported to have significant activity against several human ailments, could be exploited as potential sources of natural antioxidants for plant-based pharmaceutical industries.

  10. Ozone loss rates in the Arctic winter stratosphere during 1994-2000 derived from POAM II/III and ILAS observations: Implications for relationships among ozone loss, PSC occurrence, and temperature

    NASA Astrophysics Data System (ADS)

    Terao, Yukio; Sugita, Takafumi; Sasano, Yasuhiro

    2012-03-01

    Quantitative chemical ozone loss rates at the 475 K isentropic surface inside the Arctic polar vortex are evaluated for six winters (January through March) using a satellite-based Match technique. Satellite observational data are taken from the Polar Ozone and Aerosol Measurement (POAM) II for 1994-1996, the Improved Limb Atmospheric Spectrometer (ILAS) for 1997, and the POAM III for 1999-2000. The largest ozone loss rates were observed in the end of January 1995 (˜50 ± 20 ppbv d-1), February 1996 (˜40-50 ± 15 ppbv d-1), February 1997 (˜40 ± 8 ppbv d-1), January 2000 (˜60 ± 30 ppbv d-1), and early March 2000 (˜40 ± 10 ppbv d-1). The probability of polar stratospheric cloud (PSC) existence is estimated using aerosol extinction coefficient data from POAM II/III and ILAS. Ozone loss and the PSC probability are strongly correlated and an absolute increase of 10% in the PSC probability is found to amplify the chemical ozone loss rate during Arctic winter by approximately 25 ± 6 ppbv per day or 3.2 ± 0.7 ppbv per sunlit hour. Relationships between average Arctic winter ozone loss rates and various PSC- and temperature-related indices are investigated, including the area of polar vortex that is colder than the threshold temperature for PSC existence (APSC), the PSC formation potential (PFP), and the potential for activation of chlorine (PACl). Of these three, PACl provides the best proxy representation of interannual variability in Arctic ozone loss at the 475 K level. Large ozone loss occurred primarily for air masses that experienced low temperatures between 187 K and 195 K within the previous 10 days and the ozone loss rates clearly increase with decreasing the minimum temperature. The particularly large ozone losses of ˜9 ± 3 ppbv per sunlit hour in February 1996 and January 2000 were associated with low minimum temperatures of 187-189 K, simultaneously with high PSC probabilities.

  11. Biochemical leaf traits as indicators of tolerance potential in tree species from the Brazilian Atlantic Forest against oxidative environmental stressors.

    PubMed

    Brandão, Solange E; Bulbovas, Patricia; Lima, Marcos E L; Domingos, Marisa

    2017-01-01

    The tolerance potential against the oxidative injury in native plants from forest ecosystems affected by environmental stressors depends on how efficiently they keep their pro-oxidant/antioxidant balance. Great variations in plant tolerance are expected, highlighting the higher relevance of measuring biochemical leaf trait indicators of oxidative injury in species with similar functions in the forest than in single species. The use of this functional approach seems very useful in the Brazilian Atlantic Forest because it still holds high plant diversity and was the focus of this study. We aimed at determining the tolerance potential of tree species from the Atlantic Forest remnants in SE Brazil against multiple oxidative environmental stressors. We assumed that pioneer tree species are more tolerant against oxidative stress than non-pioneer tree species and that their tolerance potential vary spatially in response to distinct combined effects of oxidative environmental stressors. The study was carried out in three Atlantic Forest remnants, which differ in physiognomy, species composition, climatic characteristics and air pollution exposure. Leaves of three pioneer and three non-pioneer species were collected from each forest remnant during wet (January 2015) and dry periods (June 2015), for analyses of non-enzymatic and enzymatic antioxidants and oxidative injury indicators. Both hypotheses were confirmed. The pioneer tree species displayed biochemical leaf traits (e.g. high levels of ascorbic acid, glutathione and carotenoids and lower lipid peroxidation) that indicate their higher potential tolerance against oxidative environmental stressors than non-pioneer species. The biochemical leaf traits of both successional groups of species varied between the forest remnants, in response to a linear combination of oxidative environmental stressors, from natural (relative humidity and temperature) and anthropogenic sources (ozone and nitrogen dioxide).

  12. Signal enhancement and low oxidation potentials for miniaturized ECL biosensors via N-butyldiethanolamine.

    PubMed

    Kirschbaum-Harriman, Stefanie; Mayer, Michael; Duerkop, Axel; Hirsch, Thomas; Baeumner, Antje J

    2017-07-07

    We present studies on ruthenium-based electrochemiluminescence (ECL) focusing on conditions supporting signal enhancement and low oxidation potentials. Low oxidation potentials (LOPs) are especially attractive for miniaturized ECL biosensors, as microfabricated electrodes tend to detach from their support when used with high currents and operated at high potentials. Furthermore, high potentials or current densities can lead to damage of typical biosensor surface coatings and biological probes. The possibility of generating LOP ECL signals at a potential below 900 mV was therefore studied for Ru(bpy)3(2+) with two typical coreactants, i.e. 2-(dibutylamino)ethanol (DBAE) and tripropylamine (TPA), as well as with the tertiary amine N-butyldiethanolamine (NBEA). Furthermore, the effect of buffer components and pH values on ECL signal generation was investigated. We could show a significant LOP ECL signal for NBEA. We found that Tris buffer, with its ability to form complexes with transition metal ions, has a positive influence on this ECL signal in terms of signal strength and LOP capabilities. Specifically, at basic pH values significant increases in ECL signals were observed at 900 mV and at 1.2 V. In fact, the ECL signal at 1.2 V was three times higher than the signal observed in phosphate buffer at a pH of 7, and it was thirty times higher than the ECL signal for TPA under these conditions. The LOP signal for NBEA in Tris buffer at pH 8.5 was similar to the signal obtained for TPA in phosphate buffer at pH 8.5 but three times higher than for TPA at pH 7.0. Interestingly, the coreactant DBAE was neither significantly influenced by the buffer system or pH nor did it present a valuable LOP ECL signal. Finally, it was found that high peak currents in cyclic voltammograms are not the indicators for high ECL signals, which should be obvious because the ECL mechanism requires more complex electron transfers. Overall, the standard TPA ECL at 1.2 V in phosphate buffer at p

  13. Oxidative stress and potential biomarkers in tomato seedlings subjected to soil lead contamination.

    PubMed

    Wang, Chengrun; Wang, Xiaorong; Tian, Yuan; Xue, Yingang; Xu, Xianghua; Sui, Yunxia; Yu, Hongxia

    2008-11-01

    Oxidative stress and defense response in leaves of tomato seedlings exposed to extraneous lead (Pb) at 0-500 mg kg(-1) soil for nearly 2 months were investigated. Superoxide radical (O(2)(-)) was quantified by electron paramagnetic resonance (EPR). Results showed that levels of O(2)(-), malondialdehyde (MDA), carbonyl group and superoxide dismutase (SOD) increased with the increase of bioavailable Pb. The O(2)(-) level was well correlated with MDA, carbonyl groups and SOD activities, suggesting that O(2)(-) might be responsible for them. Intensities in two bands of SOD isoenzymes increased along with added Pb in treatments against control, implying that multigenic expression in SOD enzymes were activated to counteract O(2)(-) stress. Heat shock protein 70 (HSP70) was induced sensitively by soil Pb, which was to alleviate oxidative damage (i.e. increased carbonyl groups). The overall results indicated that HSP70 and O(2)(-) were the most sensitive parameters and the combination of them might be potential biomarkers of soil Pb contamination in tomato seedlings.

  14. Autotrophic, Hydrogen-Oxidizing, Denitrifying Bacteria in Groundwater, Potential Agents for Bioremediation of Nitrate Contamination

    PubMed Central

    Smith, Richard L.; Ceazan, Marnie L.; Brooks, Myron H.

    1994-01-01

    Addition of hydrogen or formate significantly enhanced the rate of consumption of nitrate in slurried core samples obtained from an active zone of denitrification in a nitrate-contaminated sand and gravel aquifer (Cape Cod, Mass.). Hydrogen uptake by the core material was immediate and rapid, with an apparent Km of 0.45 to 0.60 μM and a Vmax of 18.7 nmol cm-3 h-1 at 30°C. Nine strains of hydrogen-oxidizing denitrifying bacteria were subsequently isolated from the aquifer. Eight of the strains grew autotrophically on hydrogen with either oxygen or nitrate as the electron acceptor. One strain grew mixotrophically. All of the isolates were capable of heterotrophic growth, but none were similar to Paracoccus denitrificans, a well-characterized hydrogen-oxidizing denitrifier. The kinetics for hydrogen uptake during denitrification were determined for each isolate with substrate depletion progress curves; the Kms ranged from 0.30 to 3.32 μM, with Vmaxs of 1.85 to 13.29 fmol cell-1 h-1. Because these organisms appear to be common constituents of the in situ population of the aquifer, produce innocuous end products, and could be manipulated to sequentially consume oxygen and then nitrate when both were present, these results suggest that these organisms may have significant potential for in situ bioremediation of nitrate contamination in groundwater. PMID:16349284

  15. Potential roles of anaerobic ammonium and methane oxidation in the nitrogen cycle of wetland ecosystems.

    PubMed

    Zhu, Guibing; Jetten, Mike S M; Kuschk, Peter; Ettwig, Katharina F; Yin, Chengqing

    2010-04-01

    Anaerobic ammonium oxidation (anammox) and anaerobic methane oxidation (ANME coupled to denitrification) with nitrite as electron acceptor are two of the most recent discoveries in the microbial nitrogen cycle. Currently the anammox process has been relatively well investigated in a number of natural and man-made ecosystems, while ANME coupled to denitrification has only been observed in a limited number of freshwater ecosystems. The ubiquitous presence of anammox bacteria in marine ecosystems has changed our knowledge of the global nitrogen cycle. Up to 50% of N(2) production in marine sediments and oxygen-depleted zones may be attributed to anammox bacteria. However, there are only few indications of anammox in natural and constructed freshwater wetlands. In this paper, the potential role of anammox and denitrifying methanotrophic bacteria in natural and artificial wetlands is discussed in relation to global warming. The focus of the review is to explore and analyze if suitable environmental conditions exist for anammox and denitrifying methanotrophic bacteria in nitrogen-rich freshwater wetlands.

  16. Autotrophic, hydrogen-oxidizing, denitrifying bacteria in groundwater, potential agents for bioremediation of nitrate contamination

    USGS Publications Warehouse

    Smith, R.L.; Ceazan, M.L.; Brooks, M.H.

    1994-01-01

    Addition of hydrogen or formate significantly enhanced the rate of consumption of nitrate in slurried core samples obtained from an active zone of denitrification in a nitrate-contaminated sand and gravel aquifer (Cape Cod, Mass.). Hydrogen uptake by the core material was immediate and rapid, with an apparent K(m) of 0.45 to 0.60 ??M and a V(max) of 18.7 nmol cm-3 h-1 at 30??C. Nine strains of hydrogen-oxidizing denitrifying bacteria were subsequently isolated from the aquifer. Eight of the strains grew autotrophically on hydrogen with either oxygen or nitrate as the electron acceptor. One strain grew mixotrophically. All of the isolates were capable of heterotrophic growth, but none were similar to Paracoccus denitrificans, a well-characterized hydrogen-oxidizing denitrifier. The kinetics for hydrogen uptake during denitrification were determined for each isolate with substrate depletion progress curves; the K(m)s ranged from 0.30 to 3.32 ??M, with V(max)s of 1.85 to 13.29 fmol cell-1 h-1. Because these organisms appear to be common constituents of the in situ population of the aquifer, produce innocuous end products, and could be manipulated to sequentially consume oxygen and then nitrate when both were present, these results suggest that these organisms may have significant potential for in situ bioremediation of nitrate contamination in groundwater.

  17. Infrared Properties of Solid Titanium Oxides: Exploring Potential Primary Dust Condensates

    NASA Astrophysics Data System (ADS)

    Posch, Th.; Kerschbaum, F.; Fabian, D.; Mutschke, H.; Dorschner, J.; Tamanai, A.; Henning, Th.

    2003-12-01

    We present optical constants and opacities of solid TiO2, Ti2O3, magnesium and calcium titanates, largely based on laboratory measurements. These dust species deserve interest as potential primary condensates in oxygen-rich dusty environments. Of the three known solid TiO2 phases, only one (rutile) has been extensively studied so far with respect to its mid-IR optical properties. We compare these with our measurements of the optical constants of anatase, brookite, and CaTiO3. Furthermore, for several Mg-Ti-oxides, powder transmission spectra are shown. While all known TiO2 modifications have their strongest bands between 13 and 13.5 μm (for spherical particles), CaTiO3, MgTiO3, and other Mg titanates have principal maxima of their absorption coefficients between 14 and 19 μm. This makes a spectroscopic identification of circumstellar Ti oxide particles rather difficult, because both the 13 and the 14-19 μm region are crowded with other features in the spectra of oxygen-rich circumstellar shells.

  18. Different electrostatic potentials define ETGE and DLG motifs as hinge and latch in oxidative stress response.

    PubMed

    Tong, Kit I; Padmanabhan, Balasundaram; Kobayashi, Akira; Shang, Chengwei; Hirotsu, Yosuke; Yokoyama, Shigeyuki; Yamamoto, Masayuki

    2007-11-01

    Nrf2 is the regulator of the oxidative/electrophilic stress response. Its turnover is maintained by Keap1-mediated proteasomal degradation via a two-site substrate recognition mechanism in which two Nrf2-Keap1 binding sites form a hinge and latch. The E3 ligase adaptor Keap1 recognizes Nrf2 through its conserved ETGE and DLG motifs. In this study, we examined how the ETGE and DLG motifs bind to Keap1 in a very similar fashion but with different binding affinities by comparing the crystal complex of a Keap1-DC domain-DLG peptide with that of a Keap1-DC domain-ETGE peptide. We found that these two motifs interact with the same basic surface of either Keap1-DC domain of the Keap1 homodimer. The DLG motif works to correctly position the lysines within the Nrf2 Neh2 domain for efficient ubiquitination. Together with the results from calorimetric and functional studies, we conclude that different electrostatic potentials primarily define the ETGE and DLG motifs as a hinge and latch that senses the oxidative/electrophilic stress.

  19. Highly Acidic Ambient Particles, Soluble Metals, and Oxidative Potential: A Link between Sulfate and Aerosol Toxicity.

    PubMed

    Fang, Ting; Guo, Hongyu; Zeng, Linghan; Verma, Vishal; Nenes, Athanasios; Weber, Rodney J

    2017-03-07

    Soluble transition metals in particulate matter (PM) can generate reactive oxygen species in vivo by redox cycling, leading to oxidative stress and adverse health effects. Most metals, such as those from roadway traffic, are emitted in an insoluble form, but must be soluble for redox cycling. Here we present the mechanism of metals dissolution by highly acidic sulfate aerosol and the effect on particle oxidative potential (OP) through analysis of size distributions. Size-segregated ambient PM were collected from a road-side and representative urban site in Atlanta, GA. Elemental and organic carbon, ions, total and water-soluble metals, and water-soluble OP were measured. Particle pH was determined with a thermodynamic model using measured ionic species. Sulfate was spatially uniform and found mainly in the fine mode, whereas total metals and mineral dust cations were highest at the road-side site and in the coarse mode, resulting in a fine mode pH < 2 and near neutral coarse mode. Soluble metals and OP peaked at the intersection of these modes demonstrating that sulfate plays a key role in producing highly acidic fine aerosols capable of dissolving primary transition metals that contribute to aerosol OP. Sulfate-driven metals dissolution may account for sulfate-health associations reported in past studies.

  20. Galvanic Corrosion of Lead by Iron (Oxyhydr)Oxides: Potential Impacts on Drinking Water Quality.

    PubMed

    Trueman, Benjamin F; Sweet, Gregory A; Harding, Matthew D; Estabrook, Hayden; Bishop, D Paul; Gagnon, Graham A

    2017-06-20

    Lead exposure via drinking water remains a significant public health risk; this study explored the potential effects of upstream iron corrosion on lead mobility in water distribution systems. Specifically, galvanic corrosion of lead by iron (oxyhydr)oxides was investigated. Coupling an iron mineral cathode with metallic lead in a galvanic cell increased lead release by 531 μg L(-1) on average-a 9-fold increase over uniform corrosion in the absence of iron. Cathodes were composed of spark plasma sintered Fe3O4 or α-Fe2O3 or field-extracted Fe3O4 and α-FeOOH. Orthophosphate immobilized oxidized lead as insoluble hydroxypyromorphite, while humic acid enhanced lead mobility. Addition of a humic isolate increased lead release due to uniform corrosion by 81 μg L(-1) and-upon coupling lead to a mineral cathode-release due to galvanic corrosion by 990 μg L(-1). Elevated lead in the presence of humic acid appeared to be driven by complexation, with (208)Pb and UV254 size-exclusion chromatograms exhibiting strong correlation under these conditions (R(2)average = 0.87). A significant iron corrosion effect was consistent with field data: lead levels after lead service line replacement were greater by factors of 2.3-4.7 at sites supplied by unlined cast iron distribution mains compared with the alternative, lined ductile iron.

  1. The NMR structure of the II-III-VI three-way junction from the Neurospora VS ribozyme reveals a critical tertiary interaction and provides new insights into the global ribozyme structure.

    PubMed

    Bonneau, Eric; Girard, Nicolas; Lemieux, Sébastien; Legault, Pascale

    2015-09-01

    As part of an effort to structurally characterize the complete Neurospora VS ribozyme, NMR solution structures of several subdomains have been previously determined, including the internal loops of domains I and VI, the I/V kissing-loop interaction and the III-IV-V junction. Here, we expand this work by determining the NMR structure of a 62-nucleotide RNA (J236) that encompasses the VS ribozyme II-III-VI three-way junction and its adjoining stems. In addition, we localize Mg(2+)-binding sites within this structure using Mn(2+)-induced paramagnetic relaxation enhancement. The NMR structure of the J236 RNA displays a family C topology with a compact core stabilized by continuous stacking of stems II and III, a cis WC/WC G•A base pair, two base triples and two Mg(2+) ions. Moreover, it reveals a remote tertiary interaction between the adenine bulges of stems II and VI. Additional NMR studies demonstrate that both this bulge-bulge interaction and Mg(2+) ions are critical for the stable folding of the II-III-VI junction. The NMR structure of the J236 RNA is consistent with biochemical studies on the complete VS ribozyme, but not with biophysical studies performed with a minimal II-III-VI junction that does not contain the II-VI bulge-bulge interaction. Together with previous NMR studies, our findings provide important new insights into the three-dimensional architecture of this unique ribozyme.

  2. Synergism of Water Shock and a Biocompatible Block Copolymer Potentiates the Antibacterial Activity of Graphene Oxide.

    PubMed

    Karahan, H Enis; Wei, Li; Goh, Kunli; Wiraja, Christian; Liu, Zhe; Xu, Chenjie; Jiang, Rongrong; Wei, Jun; Chen, Yuan

    2016-02-17

    Graphene oxide (GO) is promising in the fight against pathogenic bacteria. However, the antibacterial activity of pristine GO is relatively low and concern over human cytotoxicity further limits its potential. This study demonstrates a general approach to address both issues. The developed approach synergistically combines the water shock treatment (i.e., a sudden decrease in environmental salinity) and the use of a biocompatible block copolymer (Pluronic F-127) as a synergist co-agent. Hypoosmotic stress induced by water shock makes gram-negative pathogens more susceptible to GO. Pluronic forms highly stable nanoassemblies with GO (Pluronic-GO) that can populate around bacterial envelopes favoring the interactions between GO and bacteria. The antibacterial activity of GO at a low concentration (50 μg mL(-1) ) increases from <30% to virtually complete killing (>99%) when complemented with water shock and Pluronic (5 mg mL(-1) ) at ≈2-2.5 h of exposure. Results suggest that the enhanced dispersion of GO and the osmotic pressure generated on bacterial envelopes by polymers together potentiate GO. Pluronic also significantly suppresses the toxicity of GO toward human fibroblast cells. Fundamentally, the results highlight the crucial role of physicochemical milieu in the antibacterial activity of GO. The demonstrated strategy has potentials for daily-life bacterial disinfection applications, as hypotonic Pluronic-GO mixture is both safe and effective.

  3. Clinical consequences of urea cycle enzyme deficiencies and potential links to arginine and nitric oxide metabolism.

    PubMed

    Scaglia, Fernando; Brunetti-Pierri, Nicola; Kleppe, Soledad; Marini, Juan; Carter, Susan; Garlick, Peter; Jahoor, Farook; O'Brien, William; Lee, Brendan

    2004-10-01

    Urea cycle disorders (UCD) are human conditions caused by the dysregulation of nitrogen transfer from ammonia nitrogen into urea. The biochemistry and the genetics of these disorders were well elucidated. Earlier diagnosis and improved treatments led to an emerging, longer-lived cohort of patients. The natural history of some of these disorders began to point to pathophysiological processes that may be unrelated to the primary cause of acute morbidity and mortality, i.e., hyperammonemia. Carbamyl phosphate synthetase I single nucleotide polymorphisms may be associated with altered vascular resistance that becomes clinically relevant when specific environmental stressors are present. Patients with argininosuccinic aciduria due to a deficiency of argininosuccinic acid lyase are uniquely prone to chronic hepatitis, potentially leading to cirrhosis. Moreover, our recent observations suggest that there may be an increased prevalence of essential hypertension. In contrast, hyperargininemia found in patients with arginase 1 deficiency is associated with pyramidal tract findings and spasticity, without significant hyperammonemia. An intriguing potential pathophysiological link is the dysregulation of intracellular arginine availability and its potential effect on nitric oxide (NO) metabolism. By combining detailed natural history studies with the development of tissue-specific null mouse models for urea cycle enzymes and measurement of nitrogen flux through the cycle to urea and NO in UCD patients, we may begin to dissect the contribution of different sources of arginine to NO production and the consequences on both rare genetic and common multifactorial diseases.

  4. Neuroprotective potential of cerium oxide nanoparticles for focal cerebral ischemic stroke.

    PubMed

    Zhou, Da; Fang, Ting; Lu, Lin-Qing; Yi, Li

    2016-08-01

    During the previous years, with the emerging of nanotechnology, the enormous capabilities of nanoparticles have drawn great attention from researchers in terms of their potentials in various aspects of pharmacology. Cerium oxide nanoparticles (nanoceria), considered as one of the most widely used nanomaterials, due to its tempting catalytic antioxidant properties, show a promising potential in diverse disorders, such as cerebral ischemic stroke (CIS), cancer, neurodegenerative and inflammatory diseases. Overwhelming generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) during cerebral ischemia and reperfusion periods is known to aggravate brain damage via sophisticated cellular and molecular mechanisms, and therefore exploration of the antioxidant capacities of nanoceria becomes a new approach in reducing cerebral ischemic injury. Furthermore, utilizing nanoceria as a drug carrier might display the propensity to overcome limitations or inefficacy of other conceivable neuroprotectants and exhibit synergistic effects. In this review, we emphasize on the principle features of nanoceria and current researches concerning nanoceria as a potential therapeutic agent or carrier in improving the prognosis of CIS.

  5. Cathodic shift of onset potential for water oxidation of WO3 photoanode by Zr+ ions implantation

    NASA Astrophysics Data System (ADS)

    Wu, Hengyi; Ren, Feng; Xing, Zhuo; Zheng, Xudong; Wu, Liang; Jiang, Changzhong

    2017-02-01

    Tungsten trioxide is one of the most widely studied semiconductors for photoelectrochemical water splitting. However, its onset potential is too positive. In a photoelectrochemical system, a low onset potential and a high photocurrent for a photoanode are important for enhancing the efficiency of water splitting. It is an effective way to adjust the onset potential by changing the conduction and valence band level. Doping is a powerful way to alter the positions of the energy levels of semiconductors to improve their photoelectrochemical performance. In this paper, we present a method of ion implantation to alter the energy levels by implanting Zr+ ions into WO3. Cathodic shifts of the photocurrent onset potential for water oxidation are achieved. The systematic studies show that ion implantation followed by thermal annealing treatment can form substitutional Zr4+ in WO3. The upward shifts of the conduction band and valence band lead to the cathodic shifts of the onset potential. Two combined factors lead to the upward shift of the conduction band. One is strain induced after doping in the lattices. Another is due to the higher energy level of the Zr 4d orbital than the W 5d orbital. Meanwhile, the oxygen vacancy introduced during the ion implantation can cause an upward shift the valence band maximum. The results indicate that the upward shifts of the conduction band minimum and valence band maximum are good for the photoelectrochemical water splitting. It also shows that an ion implantation technique combined with thermal annealing could be an effective way to enhance the performance of the photoanode for water splitting.

  6. Effectiveness of oxidative potential water as an irrigant in pulpectomized primary teeth.

    PubMed

    Valdez-Gonzalez, C; Mendez-Gonzalez, V; Torre-Delgadillo, G; Flores-Reyes, H; Gaitan-Fonseca, C; Pozos-Guillen, A J

    2012-01-01

    The aim of this study was to evaluate the effectiveness of oxidative potential water (OPW) as an irrigating solution in reducing bacterial loading in necrotic pulpectomized primary teeth. Forty necrotic teeth were included, 20 irrigated with OPW (experimental group) and 20 with 1% NaOCl (control group); in both groups, 2 microbiological samples from within the canals were taken with a sterile paper point, the first before irrigation (immediately before opening the crown), and the second after instrumentation and final irrigation (before filling). All samples were evaluated by McFarland's scale. After the samples were analyzed before and after irrigation in the control group, there was a significant decrease in bacterial load, as in the experimental group (P < 0.0001). When both groups were compared post irrigation, no significant difference was observed (P = 0.1519). The OPW was as effective as the NaOCl and is suggested as an alternative for irrigating after pulpectomy of necrotic primary teeth.

  7. Iridium oxide nanotube electrodes for sensitive and prolonged intracellular measurement of action potentials.

    PubMed

    Lin, Ziliang Carter; Xie, Chong; Osakada, Yasuko; Cui, Yi; Cui, Bianxiao

    2014-01-01

    Intracellular recording of action potentials is important to understand electrically-excitable cells. Recently, vertical nanoelectrodes have been developed to achieve highly sensitive, minimally invasive and large-scale intracellular recording. It has been demonstrated that the vertical geometry is crucial for the enhanced signal detection. Here we develop nanoelectrodes of a new geometry, namely nanotubes of iridium oxide. When cardiomyocytes are cultured upon those nanotubes, the cell membrane not only wraps around the vertical tubes but also protrudes deep into the hollow centre. We show that this nanotube geometry enhances cell-electrode coupling and results in larger signals than solid nanoelectrodes. The nanotube electrodes also afford much longer intracellular access and are minimally invasive, making it possible to achieve stable recording up to an hour in a single session and more than 8 days of consecutive daily recording. This study suggests that the nanoelectrode performance can be significantly improved by optimizing the electrode geometry.

  8. Tetranitroacetimidic acid: a high oxygen oxidizer and potential replacement for ammonium perchlorate.

    PubMed

    Vo, Thao T; Parrish, Damon A; Shreeve, Jean'ne M

    2014-08-27

    Considerable work has been focused on developing replacements for ammonium perchlorate (AP), a primary choice for solid rocket and missile propellants, due to environmental concerns resulting from the release of perchlorate into groundwater systems [corrected]. Additionally, the generation of hydrochloric acid contributes to high concentrations of acid rain and to ozone layer depletion. En route to synthesizing salts that contain cationic FOX-7, a novel, high oxygen-containing oxidizer, tetranitroacetimidic acid (TNAA), has been synthesized and fully characterized. The properties of TNAA were found to be exceptional, with a calculated specific impulse exceeding that of AP, leading to its high potential as a replacement for AP. TNAA can be synthesized easily in a one-step process by the nitration of FOX-7 in high yield (>93%). The synthesis, properties, and chemical reactivity of TNAA have been examined.

  9. Influence of oxygen content of the certain types of biodiesels on particulate oxidative potential.

    PubMed

    Hedayat, F; Stevanovic, S; Milic, A; Miljevic, B; Nabi, M N; Zare, A; Bottle, S E; Brown, R J; Ristovski, Z D

    2016-03-01

    Oxidative potential (OP) is related to the organic phase, specifically to its oxygenated organic fraction (OOA). Furthermore, the oxygen content of fuel molecules has significant influence on particulate OP. Thus, this study aimed to explore the actual dependency of the OOA and ROS to the oxygen content of the fuel. In order to reach the goal, different biodiesels blends, with various ranges of oxygen content; have been employed. The compact time of flight aerosol mass spectrometer (c-ToF AMS) enabled better identification of OOA. ROS monitored by using two assays: DTT and BPEA-nit. Despite emitting lower mass, both assays agreed that oxygen content of a biodiesel is directly correlated with its OOA, and highly related to its OP. Hence, the more oxygen included in the considered biodiesels, the higher the OP of PM emissions. This highlights the importance of taking oxygen content into account while assessing emissions from new fuel types, which is relevant from a health effects standpoint.

  10. Potential use of Cytisus scoparius extracts in topical applications for skin protection against oxidative damage.

    PubMed

    González, Noelia; Ribeiro, Daniela; Fernandes, Eduarda; Nogueira, Daniele R; Conde, Enma; Moure, Andrés; Vinardell, María Pilar; Mitjans, Montserrat; Domínguez, Herminia

    2013-08-05

    Cytisus scoparius L. is used in folk medicine for the treatment of several ailments in which the antioxidant and anti-inflammatory effects of its carotenoid and flavonoid content is suggested to play an important role. We postulate that flavonoid- and carotenoid-rich extracts from C. scoparius may become useful in the preparation of formulations for topical application to protect the skin against oxidative damage mediated by high energy UV light radiation. The aim of this work was to apply an extraction process to obtain a bioactive extract from C. scoparius for the potential use in topical applications. Aqueous and ethanolic extracts from C. scoparius were characterized for its reducing capacity, radical scavenging capacity, and on the reactive oxygen and nitrogen species (ROS, RNS). The extracts showed activities comparable to that of synthetic antioxidants, and absence of skin-irritant effects at 1%. Those make them good candidates to be used in topical applications as active ingredients.

  11. Exhaled nasal nitric oxide during humming: potential clinical tool in sinonasal disease?

    PubMed

    Maniscalco, Mauro; Pelaia, Girolamo; Sofia, Matteo

    2013-04-01

    The use of nasal nitric oxide (nNO) in sinonasal disease has recently been advocated as a potential tool to explore upper inflammatory airway disease. However, it is currently hampered by some factors including the wide range of measurement methods, the presence of various confounding factors and the heterogeneity of the study population. The contribution of nasal airway and paranasal sinuses communicating with the nose through the ostia represents the main confounding factor. There is accumulating evidence that nasal humming (which is the production of a tone without opening the lips or forming words) during nNO measurement increases nNO levels due to a rapid gas exchange in the paranasal sinuses. The aim of this review is to discuss the basic concepts and clinical applications of nNO assessment during humming, which represents a simple and noninvasive method to approach sinonasal disease.

  12. Analysis of flow decay potential on Galileo. [oxidizer flow rate reduction by iron nitrate precipitates

    NASA Technical Reports Server (NTRS)

    Cole, T. W.; Frisbee, R. H.; Yavrouian, A. H.

    1987-01-01

    The risks posed to the NASA's Galileo spacecraft by the oxidizer flow decay during its extended mission to Jupiter is discussed. The Galileo spacecraft will use nitrogen tetroxide (NTO)/monomethyl hydrazine bipropellant system with one large engine thrust-rated at a nominal 400 N, and 12 smaller engines each thrust-rated at a nominal 10 N. These smaller thrusters, because of their small valve inlet filters and small injector ports, are especially vulnerable to clogging by iron nitrate precipitates formed by NTO-wetted stainless steel components. To quantify the corrosion rates and solubility levels which will be seen during the Galileo mission, corrosion and solubility testing experiments were performed with simulated Galileo materials, propellants, and environments. The results show the potential benefits of propellant sieving in terms of iron and water impurity reduction.

  13. Oxidative potential of some endophytic fungi using 1-indanone as a substrate.

    PubMed

    Fill, Taicia Pacheco; da Silva, Jose Vinicius; de Oliveira, Kleber Thiago; da Silva, Bianca Ferreira; Rodrigues-Fo, Edson

    2012-06-01

    The oxidative potential of the fungus Penicillium brasilianum, a strain isolated as an endophyte from a Meliaceae plant (Melia azedarach), was investigated using 1-indanone as a substrate to track the production of monooxygenases. The fungus produced the dihydrocoumarin from 1-indanone with the classical Baeyer-Villiger reaction regiochemistry, and (-)-(R)-3-hydroxy-1-indanone with 78% ee. Minor compounds resulting from lipase and SAM activities were also detected. The biotransformation procedures were also applied to a collection of Penicillium and Aspergillus fungi obtained from M. azedarach and Murraya paniculata. The results showed that Baeyer-Villiger were mostly active in fungi isolated from M. azedarach. Almost all of the fungi tested produced 3-hydroxy-1-indanone..

  14. Antioxidant potential of silk protein sericin against hydrogen peroxide-induced oxidative stress in skin fibroblasts.

    PubMed

    Dash, Rupesh; Acharya, Chitrangada; Bindu, P C; Kundu, S C

    2008-03-31

    The antioxidant potential of silk protein sericin from the non-mulberry tropical tasar silkworm Antheraea mylitta cocoon has been assessed and compared with that of the mulberry silkworm, Bombyx mori. Skin fibroblast cell line (AH927) challenged with hydrogen peroxide served as the positive control for the experiment. Our results showed that the sericin obtained from tasar cocoons offers protection against oxidative stress and cell viability is restored to that of control on pre-incubation with the sericin. Fibroblasts pre-incubated with non-mulberry sericin had significantly lower levels of catalase; lactate dehydrogenase and malondialdehyde activity when compared to untreated ones. This report indicates that the silk protein sericin from the non-mulberry tropical tasar silkworm, A. mylitta can serve as a valuable antioxidant.

  15. Climate change reduces warming potential of nitrous oxide by an enhanced Brewer-Dobson circulation

    NASA Astrophysics Data System (ADS)

    Kracher, Daniela; Reick, Christian H.; Manzini, Elisa; Schultz, Martin G.; Stein, Olaf

    2016-06-01

    The Brewer-Dobson circulation (BDC), which is an important driver of the stratosphere-troposphere exchange, is expected to accelerate with climate change. One particular consequence of this acceleration is the enhanced transport of nitrous oxide (N2O) from its sources at the Earth's surface toward its main sink region in the stratosphere, thus inducing a reduction in its lifetime. N2O is a potent greenhouse gas and the most relevant currently emitted ozone-depleting substance. Here we examine the implications of a reduced N2O lifetime in the context of climate change. We find a decrease in its global warming potential (GWP) and, due to a decline in the atmospheric N2O burden, also a reduction in its total radiative forcing. From the idealized transient global warming simulation we can identify linear regressions for N2O sink, lifetime, and GWP with temperature rise. Our findings are thus not restricted to a particular scenario.

  16. Recent knowledge concerning mammalian sperm chromatin organization and its potential weaknesses when facing oxidative challenge.

    PubMed

    Noblanc, Anais; Kocer, Ayhan; Drevet, Joël R

    2014-01-01

    Spermatozoa are the smallest and most cyto-differentiated mammalian cells. From a somatic cell-like appearance at the beginning of spermatogenesis, the male germ cell goes through a highly sophisticated process to reach its final organization entirely devoted to its mission which is to deliver the paternal genome to the oocyte. In order to fit the paternal DNA into the tiny spermatozoa head, complete chromatin remodeling is necessary. This review essentially focuses on present knowledge of this mammalian sperm nucleus compaction program. Particular attention is given to most recent advances that concern the specific organization of mammalian sperm chromatin and its potential weaknesses. Emphasis is placed on sperm DNA oxidative damage that may have dramatic consequences including infertility, abnormal embryonic development and the risk of transmission to descendants of an altered paternal genome.

  17. Links between Ammonia Oxidizer Community Structure, Abundance, and Nitrification Potential in Acidic Soils ▿ †

    PubMed Central

    Yao, Huaiying; Gao, Yangmei; Nicol, Graeme W.; Campbell, Colin D.; Prosser, James I.; Zhang, Limei; Han, Wenyan; Singh, Brajesh K.

    2011-01-01

    Ammonia oxidation is the first and rate-limiting step of nitrification and is performed by both ammonia-oxidizing archaea (AOA) and bacteria (AOB). However, the environmental drivers controlling the abundance, composition, and activity of AOA and AOB communities are not well characterized, and the relative importance of these two groups in soil nitrification is still debated. Chinese tea orchard soils provide an excellent system for investigating the long-term effects of low pH and nitrogen fertilization strategies. AOA and AOB abundance and community composition were therefore investigated in tea soils and adjacent pine forest soils, using quantitative PCR (qPCR), terminal restriction fragment length polymorphism (T-RFLP) and sequence analysis of respective ammonia monooxygenase (amoA) genes. There was strong evidence that soil pH was an important factor controlling AOB but not AOA abundance, and the ratio of AOA to AOB amoA gene abundance increased with decreasing soil pH in the tea orchard soils. In contrast, T-RFLP analysis suggested that soil pH was a key explanatory variable for both AOA and AOB community structure, but a significant relationship between community abundance and nitrification potential was observed only for AOA. High potential nitrification rates indicated that nitrification was mainly driven by AOA in these acidic soils. Dominant AOA amoA sequences in the highly acidic tea soils were all placed within a specific clade, and one AOA genotype appears to be well adapted to growth in highly acidic soils. Specific AOA and AOB populations dominated in soils at particular pH values and N content, suggesting adaptation to specific niches. PMID:21571885

  18. Genotoxic potential of copper oxide nanoparticles in the bivalve mollusk Mytilus trossulus

    NASA Astrophysics Data System (ADS)

    Chelomin, Victor P.; Slobodskova, Valentina V.; Zakhartsev, Maksim; Kukla, Sergey

    2017-04-01

    Copper oxide nanoparticles (CuO-NPs) are among the most widely used metal oxide nanoparticles, which increases the chance of their being released into the marine environment. As the applications of these particles have increased in recent years, their potential impact on the health of marine biota has also increased. However, the toxicological effects of these NPs in the marine environment are poorly known. In the present study, the DNA damaging potential of CuO-NPs in the marine eastern mussel Mytilus trossulus was evaluated and compared to that of dissolved copper exposures. Genotoxicity was assessed by the single cell gel electrophoresis (comet) assay in mussel gill and digestive gland cells. The results showed that copper in both forms (CuO-NPs and dissolved copper) was accumulated to different extents in mussel tissues. The mussel exposed to the dissolved copper attained higher concentrations of copper in the gills than in the digestive gland. In contrast to these results, it was found that CuO-NPs could induce much higher copper accumulation in the digestive gland than in the gills. A clear and statistically significant increase in DNA damage was found in both tissues of the Cu-exposed group compared to the control mussels. Our results indicated that the CuO-NP exposure produced remarkable effects and increased DNA damage significantly in mussel gill cells only. It should be noted that the digestive gland cells were prone to accumulation following CuO-NPs when compared to the gill cells, while the gill cells were more sensitive to the genotoxic effects of CuO-NPs. These results also suggested the need for a complete risk assessment of engineered particles before its arrival in the consumer market.

  19. Oxidative potential and inflammatory impacts of source apportioned ambient air pollution in Beijing.

    PubMed

    Liu, Qingyang; Baumgartner, Jill; Zhang, Yuanxun; Liu, Yanju; Sun, Yongjun; Zhang, Meigen

    2014-11-04

    Air pollution exposure is associated with a range of adverse health impacts. Knowledge of the chemical components and sources of air pollution most responsible for these health effects could lead to an improved understanding of the mechanisms of such effects and more targeted risk reduction strategies. We measured daily ambient fine particulate matter (<2.5 μm in aerodynamic diameter; PM2.5) for 2 months in peri-urban and central Beijing, and assessed the contribution of its chemical components to the oxidative potential of ambient air pollution using the dithiothreitol (DTT) assay. The composition data were applied to a multivariate source apportionment model to determine the PM contributions of six sources or factors: a zinc factor, an aluminum factor, a lead point factor, a secondary source (e.g., SO4(2-), NO3(2-)), an iron source, and a soil dust source. Finally, we assessed the relationship between reactive oxygen species (ROS) activity-related PM sources and inflammatory responses in human bronchial epithelial cells. In peri-urban Beijing, the soil dust source accounted for the largest fraction (47%) of measured ROS variability. In central Beijing, a secondary source explained the greatest fraction (29%) of measured ROS variability. The ROS activities of PM collected in central Beijing were exponentially associated with in vivo inflammatory responses in epithelial cells (R2=0.65-0.89). We also observed a high correlation between three ROS-related PM sources (a lead point factor, a zinc factor, and a secondary source) and expression of an inflammatory marker (r=0.45-0.80). Our results suggest large differences in the contribution of different PM sources to ROS variability at the central versus peri-urban study sites in Beijing and that secondary sources may play an important role in PM2.5-related oxidative potential and inflammatory health impacts.

  20. Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans.

    PubMed

    Burgomaster, Kirsten A; Hughes, Scott C; Heigenhauser, George J F; Bradwell, Suzanne N; Gibala, Martin J

    2005-06-01

    Parra et al. (Acta Physiol. Scand 169: 157-165, 2000) showed that 2 wk of daily sprint interval training (SIT) increased citrate synthase (CS) maximal activity but did not change "anaerobic" work capacity, possibly because of chronic fatigue induced by daily training. The effect of fewer SIT sessions on muscle oxidative potential is unknown, and aside from changes in peak oxygen uptake (Vo(2 peak)), no study has examined the effect of SIT on "aerobic" exercise capacity. We tested the hypothesis that six sessions of SIT, performed over 2 wk with 1-2 days rest between sessions to promote recovery, would increase CS maximal activity and endurance capacity during cycling at approximately 80% Vo(2 peak). Eight recreationally active subjects [age = 22 +/- 1 yr; Vo(2 peak) = 45 +/- 3 ml.kg(-1).min(-1) (mean +/- SE)] were studied before and 3 days after SIT. Each training session consisted of four to seven "all-out" 30-s Wingate tests with 4 min of recovery. After SIT, CS maximal activity increased by 38% (5.5 +/- 1.0 vs. 4.0 +/- 0.7 mmol.kg protein(-1).h(-1)) and resting muscle glycogen content increased by 26% (614 +/- 39 vs. 489 +/- 57 mmol/kg dry wt) (both P < 0.05). Most strikingly, cycle endurance capacity increased by 100% after SIT (51 +/- 11 vs. 26 +/- 5 min; P < 0.05), despite no change in Vo(2 peak). The coefficient of variation for the cycle test was 12.0%, and a control group (n = 8) showed no change in performance when tested approximately 2 wk apart without SIT. We conclude that short sprint interval training (approximately 15 min of intense exercise over 2 wk) increased muscle oxidative potential and doubled endurance capacity during intense aerobic cycling in recreationally active individuals.

  1. Effects of SAC on oxidative stress and NO availability in placenta: potential benefits to preeclampsia.

    PubMed

    Yu, J; Feng, L; Hu, Y; Zhou, Y

    2012-06-01

    , while SAC could antagonize this insult. And SAC also possesses the ability to increase NO and cGMP level at non-oxidative stress status in TEV-1 cells and placenta explants. SAC is therefore hypothesized to be a potential drug for PE treatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Biological versus mineralogical chromium reduction: potential for reoxidation by manganese oxide.

    PubMed

    Butler, Elizabeth C; Chen, Lixia; Hansel, Colleen M; Krumholz, Lee R; Elwood Madden, Andrew S; Lan, Ying

    2015-11-01

    Hexavalent chromium (Cr(vi), present predominantly as CrO4(2-) in water at neutral pH) is a common ground water pollutant, and reductive immobilization is a frequent remediation alternative. The Cr(iii) that forms upon microbial or abiotic reduction often co-precipitates with naturally present or added iron (Fe), and the stability of the resulting Fe-Cr precipitate is a function of its mineral properties. In this study, Fe-Cr solids were formed by microbial Cr(vi) reduction using Desulfovibrio vulgaris strain RCH1 in the presence of the Fe-bearing minerals hematite, aluminum substituted goethite (Al-goethite), and nontronite (NAu-2, Clay Minerals Society), or by abiotic Cr(vi) reduction by dithionite reduced NAu-2 or iron sulfide (FeS). The properties of the resulting Fe-Cr solids and their behavior upon exposure to the oxidant manganese (Mn) oxide (birnessite) differed significantly. In microcosms containing strain RCH1 and hematite or Al-goethite, there was significant initial loss of Cr(vi) in a pattern consistent with adsorption, and significant Cr(vi) was found in the resulting solids. The solid formed when Cr(vi) was reduced by FeS contained a high proportion of Cr(iii) and was poorly crystalline. In microcosms with strain RCH1 and hematite, Cr precipitates appeared to be concentrated in organic biofilms. Reaction between birnessite and the abiotically formed Cr(iii) solids led to production of significant dissolved Cr(vi) compared to the no-birnessite controls. This pattern was not observed in the solids generated by microbial Cr(vi) reduction, possibly due to re-reduction of any Cr(vi) generated upon oxidation by birnessite by active bacteria or microbial enzymes. The results of this study suggest that Fe-Cr precipitates formed in groundwater remediation may remain stable only in the presence of active anaerobic microbial reduction. If exposed to environmentally common Mn oxides such as birnessite in the absence of microbial activity, there is the potential

  3. Short-term associations between particle oxidative potential and daily mortality and hospital admissions in London.

    PubMed

    Atkinson, Richard W; Samoli, Evangelia; Analitis, Antonis; Fuller, Gary W; Green, David C; Anderson, H Ross; Purdie, Esme; Dunster, Chrissi; Aitlhadj, Layla; Kelly, Frank J; Mudway, Ian S

    2016-08-01

    Particulate matter (PM) from traffic and other sources has been associated with adverse health effects. One unifying theory is that PM, whatever its source, acts on the human body via its capacity to cause damaging oxidation reactions related to its content of pro-oxidants components. Few epidemiological studies have investigated particle oxidative potential (OP) and health. We conducted a time series analysis to assess associations between daily particle OP measures and numbers of deaths and hospital admissions for cardiovascular and respiratory diseases. During 2011 and 2012 particles with an aerodynamic diameter less than 2.5 and 10μm (PM2.5 and PM10 respectively) were collected daily on Partisol filters located at an urban background monitoring station in Central London. Particulate OP was assessed based on the capacity of the particles to oxidize ascorbate (OP(AA)) and glutathione (OP(GSH)) from a simple chemical model reflecting the antioxidant composition of human respiratory tract lining fluid. Particulate OP, expressed as % loss of antioxidant per μg of PM, was then multiplied by the daily concentrations of PM to derive the daily OP of PM mass concentrations (% loss per m(3)). Daily numbers of deaths and age- and cause-specific hospital admissions in London were obtained from national registries. Poisson regression accounting for seasonality and meteorology was used to estimate the percentage change in risk of death or admission associated with an interquartile increment in particle OP. We found little evidence for adverse associations between OP(AA) and OP(GSH) and mortality. Associations with cardiovascular admissions were generally positive in younger adults and negative in older adults with confidence intervals including 0%. For respiratory admissions there was a trend, from positive to negative associations, with increasing age although confidence intervals generally included 0%. Our study, the first to analyse daily particle OP measures and

  4. Characterization and Functionalization of Iron-Oxide Nanoparticles for Use as Potential Agents for Cancer Thermotherapy

    NASA Astrophysics Data System (ADS)

    O'Reilly, Nora

    This thesis presents experimental studies of iron oxide nanoparticle synthesis, functionalization, and intracellular hyperthermal effects on murine macrophages as a model in vitro system. Colloidal suspensions of magnetic nanoparticles (MNPs) are of particular interest in Magnetic Fluid Hyperthermia (MFH). Iron oxide nanoparticles (IONPs) have garnered great interest as economical, biocompatible hyperthermia agents due to their superparamagnetic activity. Here we seek to optimize the synthetic reproducibility and in vitro utilization of IONPs for application in MFH. We compared aqueous synthetic protocols and various protective coating techniques using various analytical techniques and in vitro assays to assess the biocompatibility and feasibility of the various preparations of nanoparticles. Using a co-precipitation of iron salts methodology, iron oxide nanoparticles (IONPs) with an average diameter of 6-8nm were synthesized and stabilized with carboxylates. By performing calorimetry measurements in an oscillating magnetic field (OMF) with a frequency of 500 kHz and field strength of 0.008Tesla the superparamagnetic behavior of these particles was confirmed. To further investigate these IONPs in a biological application, citric acid-stabilized particles, in conjunction with heat generated by these IONPs when exposed to an OMF, were assessed to determine their effects on cell viability in a RAW 267.4 murine macrophage model system. Our results show that 91.5-97% of cells that have ingested IONPs die follow exposure to an OMF. Importantly, neither the IONPs (at applicable concentrations) nor the OMF show cytotoxic effects. These particular particles have promising preliminary results as hyperthermic agents in both the current literature and simple, proof-of-concept experiments in our laboratory setting. We present experimental results for the synthesis, characterization, and utilization of iron oxide nanoparticles in MFH. Our results show that while IONPs have

  5. THE EFFECT OF NITRIC OXIDE ON SYNAPTIC VESICLE PROTON GRADIENT AND MITOCHONDRIAL POTENTIAL OF BRAIN NERVE TERMINALS.

    PubMed

    Tarasenko, A S

    2015-01-01

    The effect of nitric oxide on synaptic vesicle proton gradient and membrane potential of rat brain nerve terminals was studied. It has been shown that nitric oxide in the form of S-nitrosothiols at nanomolar concentrations had no effect on the studied parameters, but caused a rapid dissipation of synaptic vesicle proton gradient and depolarization of mitochondrial membrane in the presence of a SH-reducing compound such as dithiothreitol. Both processes were reversible and the rate of H(+)-gradient restoration depended on the redox potential of nerve terminals, namely the molar ratio of reductant/oxidant. This facts, as well as insensitivity of the studied processes to the inhibitor of NO-sensitive guanylate cyclase such as ODQ, allow suggesting that post-translational modification of thiol residues of the mitochondrial and synaptic vesicle proteins underlies the effect of nitric oxide on the key functional parameters ofpresynaptic nerve terminals.

  6. Chemistry of layered d-metal pnictide oxides and their potential as candidates for new superconductors

    PubMed Central

    Ozawa, Tadashi C; Kauzlarich, Susan M

    2008-01-01

    Layered d-metal pnictide oxides are a unique class of compounds which consist of characteristic d-metal pnictide layers and metal oxide layers. More than 100 of these layered compounds, including the recently discovered Fe-based superconducting pnictide oxides, can be classified into nine structure types. These structure types and the chemical and physical properties of the characteristic d-metal pnictide layers and metal oxide layers of the layered d-metal pnictide oxides are reviewed and discussed. Furthermore, possible approaches to design new superconductors based on these layered d-metal pnictide oxides are proposed. PMID:27877997

  7. Changes in oxidation-reduction potential during milk fermentation by wild lactic acid bacteria.

    PubMed

    Morandi, Stefano; Silvetti, Tiziana; Tamburini, Alberto; Brasca, Milena

    2016-08-01

    Oxidation-reduction potential (E h) is a fundamental physicochemical property of lactic acid bacteria that determines the microenvironment during the cheese manufacture and ripening. For this reason the E h is of growing interest in dairy research and the dairy industry. The objective of the study was to perform a comprehensive study on the reduction activity of wild lactic acid bacteria strains collected in different periods (from 1960 to 2012) from Italian dairy products. A total of 709 strains belonging to Lactococcus lactis, Enterococcus durans, E. faecium, E. faecalis and Streptococcus thermophilus species were studied for their reduction activity in milk. Kinetics of milk reduction were characterised by the minimum redox potential (E h7) and time of reaching E h7 (t min), the maximum difference between two measures (Δmax) and the time at which these maximum differences occurred (t*). Broad diversity in kinetic parameters was observed at both species and strain levels. E. faecalis and L. lactis resulted to be the most reducing species, while S. thermophilus was characterised by the lowest reducing power while the greatest heterogeneity was pointed out among E. durans and E. faecium strains. Considering the period of collection (1960-2012) we observed that the more recently isolated strains generally showed less reducing activity. This trend was particularly evident for the species E. durans, E. faecium and L. lactis while an opposite trend was observed in E. faecalis species. Data reported in this research provide new information for a deeper understanding of redox potential changes during milk fermentation due to bacterial growth. Gain knowledge of the redox potential of the LAB cultures could allow a better control and standardisation of cheesemaking process.

  8. Axillary Management of Stage II/III Breast Cancer in Patients Treated with Neoadjuvant Systemic Therapy: Results of CALGB 40601 (HER2-Positive) and CALGB 40603 (Triple-Negative).

    PubMed

    Ollila, David W; Cirrincione, Constance T; Berry, Donald A; Carey, Lisa A; Sikov, William M; Hudis, Clifford A; Winer, Eric P; Golshan, Mehra

    2017-04-01

    Management of the axilla in stage II/III breast cancer undergoing neoadjuvant systemic therapy (NST) is controversial. To understand current patterns of care, we collected axillary data from 2 NST trials: HER2-positive (Cancer and Leukemia Group B [CALGB] 40601) and triple-negative (CALGB 40603). Axillary evaluation pre- and post-NST was per the treating surgeon and could include sentinel node biopsy. Post-NST, node-positive patients were recommended to undergo axillary lymph node dissection (ALND). We report pre-NST histopathologic nodal evaluation and post-NST axillary surgical procedures with correlation to clinical and pathologic nodal status. Seven hundred and forty-two patients were treated, 704 had complete nodal data pre-NST and post-NST. Pre-NST, 422 (60%) of 704 patients underwent at least 1 procedure for axillary node evaluation (total of 468 procedures): fine needle aspiration (n = 234; 74% positive), core needle biopsy (n = 138; 72% positive), and sentinel node biopsy (n = 96; 33% positive). Pre-NST, 304 patients were considered node-positive. Post-NST, 304 of 704 patients (43%) underwent sentinel node biopsy; 44 were positive and 259 were negative (29 and 36 patients, respectively, had subsequent ALND). Three hundred and ninety-one (56%) patients went directly to post-NST ALND and 9 (1%) pre-NST node-positive patients had no post-NST axillary procedure. Post-NST, 170 (24%) of the 704 patients had residual axillary disease. Agreement between post-NST clinical and radiologic staging and post-NST histologic staging was strongest for node-negative (81%) and weaker for node-positive (N1 31%, N2 29%), with more than half of the clinically node-positive patients found to be pathologic negative (p < 0.001). Our results suggest there is no widely accepted standard for axillary nodal evaluation pre-NST. Post-NST staging was highly concordant in patients with N0 disease, but poorly so in node-positive disease. Accurate methods are needed to identify post

  9. The potential for mitochondrial fat oxidation in human skeletal muscle influences whole body fat oxidation during low-intensity exercise.

    PubMed

    Sahlin, K; Mogensen, M; Bagger, M; Fernström, M; Pedersen, P K

    2007-01-01

    The purpose of this study was to investigate fatty acid (FA) oxidation in isolated mitochondrial vesicles (mit) and its relation to training status, fiber type composition, and whole body FA oxidation. Trained (Vo(2 peak) 60.7 +/- 1.6, n = 8) and untrained subjects (39.5 +/- 2.0 ml.min(-1).kg(-1), n = 5) cycled at 40, 80, and 120 W, and whole body relative FA oxidation was assessed from respiratory exchange ratio (RER). Mit were isolated from muscle biopsies, and maximal ADP stimulated respiration was measured with carbohydrate-derived substrate [pyruvate + malate (Pyr)] and FA-derived substrate [palmitoyl-l-carnitine + malate (PC)]. Fiber type composition was determined from analysis of myosin heavy-chain (MHC) composition. The rate of mit oxidation was lower with PC than with Pyr, and the ratio between PC and Pyr oxidation (MFO) varied greatly between subjects (49-93%). MFO was significantly correlated to muscle fiber type distribution, i.e., %MHC I (r = 0.62, P = 0.03), but was not different between trained (62 +/- 5%) and untrained subjects (72 +/- 2%). MFO was correlated to RER during submaximal exercise at 80 (r = -0.62, P = 0.02) and 120 W (r = -0.71, P = 0.007) and interpolated 35% Vo(2 peak) (r = -0.74, P = 0.004). ADP sensitivity of mit respiration was significantly higher with PC than with Pyr. It is concluded that MFO is influenced by fiber type composition but not by training status. The inverse correlation between RER and MFO implies that intrinsic mit characteristics are of importance for whole body FA oxidation during low-intensity exercise. The higher ADP sensitivity with PC than that with Pyr may influence fuel utilization at low rate of respiration.

  10. Inorganic oxides with potential application in the preparation of a (68)Ge/(68)Ga generator system.

    PubMed

    Romero, E; Morcillo, M A

    2017-01-01

    The ion exchange properties of some tin and titanium oxides with potential application in the development of a (68)Ge/(68)Ga generator were determined. The best potential candidates, SnO2 and calcined SnO2, were further characterized by powder X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area analysis and its radiation stability was also determined. Two (68)Ge/(68)Ga pilot generators (1.85MBq) based on SnO2 and calcined SnO2 were developed and evaluated over 100 and 200 elution cycles respectively, using as eluent different concentrations of HCl. The generator based on calcined SnO2 showed higher (68)Ga elution yield and lower (68)Ge content in the eluate (75-80% and <3×10(-3)% respectively, 1-2M HCl) than the generator based on unheated SnO2 (60-65% and <1×10(-1)% respectively, 1-2M HCl). Nano-crystalline calcined SnO2 proved to be a promising sorbent; therefore it should be considered as an attractive candidate to develop (68)Ge/(68)Ga generators to produce gallium-68 for biomedical purposes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Enhancement of photoprotection potential of catechin loaded nanoemulsion gel against UVA induced oxidative stress.

    PubMed

    Harwansh, Ranjit K; Mukherjee, Pulok K; Kar, Amit; Bahadur, Shiv; Al-Dhabi, Naif Abdullah; Duraipandiyan, V

    2016-07-01

    The present study was aimed to develop a catechin (CA) loaded nanoemulsion based nano-gel for the protection of skin against ultraviolet radiation (UV) induced photo-damage and to ensure its enhanced skin permeability as well as bioavailability through transdermal route. The optimized nanoemulsion (CA-NE4) was prepared by spontaneous nano-emulsification method. It was composed of oil (ethyl oleate), Smix [surfactant (span 80) and co-surfactant (transcutol CG)] and aqueous system in an appropriate ratio of 15:62:23% w/w respectively. The CA-NE4 was characterized through assessment of droplet size, zeta potential, refractive index, transmission electron microscopy (TEM), UV, high performance thin layer chromatography (HPTLC) and Fourier transform infrared spectroscopy (FTIR) analysis. The average droplet size and zeta potential of CA-NE4 were found to be 98.6±1.01nm and -27.3±0.20mV respectively. The enhanced skin permeability was better with CA-NE4 based nano-gel (CA-NG4) [96.62%] compared to conventional gel (CA-CG) [53.01%] for a period of 24h. The enhanced % relative bioavailability (F) of CA (894.73), Cmax (93.79±6.19ngmL(-1)), AUC0-t∞ (2653.99±515.02nghmL(-1)) and Tmax (12.05±0.02h) was significantly obtained with CA-NG4 as compared to oral suspension for extended periods (72h). CA-NG4 could improve the level of cutaneous antioxidant enzymes like superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) and reduce the level of thiobarbituric acid reactive substances (TBRAS) against oxidative stress induced by UVA. Nano-gel formulation of CA showed sustained release profile and enhanced photoprotection potential due to its improved permeability as well as bioavailability (P<0.05) compared to the conventional gel. Therefore, transdermal administration of nano-gel (CA-NG4) of CA offers a better way to develop the endogenous cutaneous protection system and thus could be an effective strategy for decreasing UV-induced oxidative damage in the

  12. Long-term results and recurrence patterns from SCOPE-1: a phase II/III randomised trial of definitive chemoradiotherapy +/− cetuximab in oesophageal cancer

    PubMed Central

    Crosby, T; Hurt, C N; Falk, S; Gollins, S; Staffurth, J; Ray, R; Bridgewater, J A; Geh, J I; Cunningham, D; Blazeby, J; Roy, R; Maughan, T; Griffiths, G; Mukherjee, S

    2017-01-01

    Background: The SCOPE-1 study tested the role of adding cetuximab to conventional definitive chemoradiotherapy (dCRT), and demonstrated greater toxicity and worse survival outcomes. We present the long-term outcomes and patterns of recurrence. Methods: SCOPE-1 was a phase II/III trial in which patients were randomised to cisplatin 60 mg m−2 (day 1) and capecitabine 625 mg m−2 bd (days 1–21) for four cycles +/− cetuximab 400 mg m−2 day 1 then by 250 mg m−2 weekly. Radiotherapy consisted of 50 Gy/25# given concurrently with cycles 3 and 4. Recruitment was between February 2008 and February 2012, when the IDMC recommended closure on the basis of futility. Results: About 258 patients (dCRT=129; dCRT+cetuximab (dCRT+C)=129) were recruited from 36 centres. About 72.9% (n=188) had squamous cell histology. The median follow-up (IQR) was 46.2 (35.9–48.3) months for surviving patients. The median overall survival (OS; months; 95% CI) was 34.5 (24.7–42.3) in dCRT and 24.7 (18.6–31.3) in dCRT+C (hazard ratio (HR)=1.25, 95% CIs: 0.93–1.69, P=0.137). Median progression-free survival (PFS; months; 95% CI) was 24.1 (15.3–29.9) and 15.9 (10.7–20.8) months, respectively (HR=1.28, 95% CIs: 0.94–1.75; P=0.114). On multivariable analysis only earlier stage, full-dose RT, and higher cisplatin dose intensity were associated with improved OS. Conclusions: The mature analysis demonstrates that the dCRT regimen used in the study provided useful survival outcomes despite its use in patients who were largely unfit for surgery or who had inoperable disease. Given the competing risk of systemic and local failure, future studies should continue to focus on enhancing local control as well as optimising systemic therapy. PMID:28196063

  13. Induction TPF followed by concomitant treatment versus concomitant treatment alone in locally advanced head and neck cancer. A phase II-III trial.

    PubMed

    Ghi, M G; Paccagnella, A; Ferrari, D; Foa, P; Alterio, D; Codecà, C; Nolè, F; Verri, E; Orecchia, R; Morelli, F; Parisi, S; Mastromauro, C; Mione, C A; Rossetto, C; Polsinelli, M; Koussis, H; Loreggian, L; Bonetti, A; Campostrini, F; Azzarello, G; D'Ambrosio, C; Bertoni, F; Casanova, C; Emiliani, E; Guaraldi, M; Bunkheila, F; Bidoli, P; Niespolo, R M; Gava, A; Massa, E; Frattegiani, A; Valduga, F; Pieri, G; Cipani, T; Da Corte, D; Chiappa, F; Rulli, E

    2017-09-01

    Platinum-based chemoradiation (CCRT) is the standard treatment for Locally Advanced Head and Neck Squamous-Cell Carcinoma (LAHNSCC). Cetuximab/RT (CET/RT) is an alternative treatment option to CCRT. The efficacy of induction chemotherapy (IC) followed by chemoradiation compared to chemoradiation alone has not been demonstrated in randomized clinical trials. The goals of this phase II-III trial were to assess: (i) the overall survival (OS) of IC versus no-induction (no-IC) and (ii) the Grade 3-4 in-field mucosal toxicity of CCRT versus CET/RT. The present paper focuses on the analysis of efficacy. Patients with LAHNSCC were randomized to receive concomitant treatment alone [CCRT (Arm A1) or CET/RT (Arm A2)], or three cycles of induction docetaxel/cisplatin/5 fluorouracil (TPF) followed by CCRT (Arm B1) or followed by CET/RT (Arm B2). The superiority hypothesis of OS comparison of IC versus no-IC (Arms B1 + B2 versus A1 + A2) required 204 deaths to detect an absolute 3-year OS difference of 12% (HR 0.675, with 80% power at two-sided 5% significance level). 414 out of 421 patients were finally analyzed: 206 in the IC and 208 in the no-IC arm. Six patients were excluded because of major violation and one because of metastatic disease at diagnosis. With a median follow-up of 44.8 months, OS was significantly higher in the IC arm (HR 0.74; 95% CI 0.56-0.97; P = 0.031). Complete Responses (P = 0.0028), Progression Free Survival (P = 0.013) and the Loco-regional Control (P = 0.036) were also significantly higher in the IC arm. Compliance to concomitant treatments was not affected by induction TPF. IC followed by concomitant treatment improved the outcome of patients with LAHNSCC without compromising compliance to the concomitant treatments. The degree of the benefit of IC could be different according to the type of the subsequent concomitant strategy. NCT01086826, www.clinicaltrials.gov.

  14. Prognostic Impact of Erythropoietin Expression and Erythropoietin Receptor Expression on Locoregional Control and Survival of Patients Irradiated for Stage II/III Non-Small-Cell Lung Cancer

    SciTech Connect

    Rades, Dirk; Setter, Cornelia; Dahl, Olav; Schild, Steven E.; Noack, Frank

    2011-06-01

    Purpose: Prognostic factors can guide the physician in selecting the optimal treatment for an individual patient. This study investigates the prognostic value of erythropoietin (EPO) and EPO receptor (EPO-R) expression of tumor cells for locoregional control and survival in non-small-cell lung cancer (NSCLC) patients. Methods and Materials: Fourteen factors were investigated in 62 patients irradiated for stage II/III NSCLC, as follows: age, gender, Karnofsky performance score (KPS), histology, grading, TNM/American Joint Committee on Cancer (AJCC) stage, surgery, chemotherapy, pack years (average number of packages of cigarettes smoked per day multiplied by the number of years smoked), smoking during radiotherapy, hemoglobin levels during radiotherapy, EPO expression, and EPO-R expression. Additionally, patients with tumors expressing both EPO and EPO-R were compared to those expressing either EPO or EPO-R and to those expressing neither EPO nor EPO-R. Results: On univariate analysis, improved locoregional control was associated with AJCC stage II cancer (p < 0.048), surgery (p < 0.042), no smoking during radiotherapy (p = 0.024), and no EPO expression (p = 0.001). A trend was observed for a KPS of >70 (p = 0.08), an N stage of 0 to 1 (p = 0.07), and no EPO-R expression (p = 0.10). On multivariate analysis, AJCC stage II and no EPO expression remained significant. No smoking during radiotherapy was almost significant. On univariate analysis, improved survival was associated with N stage 0 to 1 (p = 0.009), surgery (p = 0.039), hemoglobin levels of {>=}12 g/d (p = 0.016), and no EPO expression (p = 0.001). On multivariate analysis, N stage 0 to 1 and no EPO expression maintained significance. Hemoglobin levels of {>=}12 g/d were almost significant. On subgroup analyses, patients with tumors expressing both EPO and EPO-R had worse outcomes than those expressing either EPO or EPO-R and those expressing neither EPO nor RPO-R. Conclusions: EPO expression of tumor cells

  15. SU-E-J-88: Margin Reduction of Level II/III Planning Target Volume for Image-Guided Simultaneous Integrated Boost Head-And-Neck Treatment

    SciTech Connect

    Can, S; Neylon, J; Qi, S; Santhanam, A; Low, D

    2014-06-01

    Purpose: To investigate the feasibility of improved normal tissue sparing for head-and-neck (H'N) image-guided radiotherapy (IGRT) by employing tighter CTV-to-PTV margins for target level II/III though a GPU-based deformable image registration and dose accumulation framework. Methods: Ten H'N simultaneous integrated boost cases treated on TomoTherapy were retrospectively analyzed. Weekly kVCT scans in addition to daily MVCT scans were acquired for each patient. Reduced margin plans were generated with 0- mm margin for level II and III PTV (while 3-5 mm margin for PTV1) and compared with the standard margin plan using 3-5mm margin to all CTV1-3 (reference plan). An in-house developed GPU-based 3D image deformation tool was used to register and deform the weekly KVCTs with the planning CT and determine the delivered mean/minimum/maximum dose, dose volume histograms (DVHs), etc. Results: Compared with the reference plans, the averaged cord maximum, the right and left parotid doses reduced by 22.7 %, 16.5 %, and 9 % respectively in the reduced margin plans. The V95 for PTV2 and PTV3 were found within 2 and 5% between the reference and tighter margin plans. For the reduced margin plans, the averaged cumulative mean doses were consistent with the planned dose for PTV1, PTV2 and PTV3 within 1.5%, 1.7% and 1.4%. Similar dose variations of the delivered dose were seen for the reference and tighter margin plans. The delivered maximum and mean doses for the cord were 3.55 % and 2.37% higher than the planned doses; a 5 % higher cumulative mean dose for the parotids was also observed for the delivered dose than the planned doses in both plans. Conclusion: By imposing tighter CTV-to-PTV margins for level II and III targets for H'N irradiation, acceptable cumulative doses were achievable when coupled with weekly kVCT guidance while improving normal structure sparing.

  16. Neoadjuvant triweekly nanoparticle albumin-bound paclitaxel followed by epirubicin and cyclophosphamide for Stage II/III HER2-negative breast cancer: evaluation of efficacy and safety.

    PubMed

    Shimada, Hiroko; Ueda, Shigeto; Saeki, Toshiaki; Shigekawa, Takashi; Takeuchi, Hideki; Hirokawa, Eiko; Sugitani, Ikuko; Sugiyama, Michiko; Takahashi, Takao; Matsuura, Kazuo; Yamane, Tomohiko; Kuji, Ichiei; Hasebe, Takahiro; Osaki, Akihiko

    2015-07-01

    Nanoparticle albumin-bound paclitaxel (nab-PTX) is a solvent-free paclitaxel coupled to human albumin without an associated increase in toxicity. The neoadjuvant study of primary breast cancer was planned to evaluate tumor response and safety of triweekly nanoparticle albumin-bound paclitaxel. Patients with Stage II/III HER2-negative primary breast cancer received four courses of nanoparticle albumin-bound paclitaxel 260 mg/m(2) every 3 weeks (q3w), followed by four courses of epirubicin 90 mg/m(2) plus cyclophosphamide 600 mg/m(2) q3w. Tumor response after nanoparticle albumin-bound paclitaxel was histologically evaluated. In addition, the clinical response, breast-conserving rate and safety of this treatment were monitored. Among 53 patients who received nanoparticle albumin-bound paclitaxel followed by epirubicin and cyclophosphamide neoadjuvant chemotherapy, pathological complete response and near-pathological complete response were confirmed in 3 (5.7%) and 7 (13.2%) patients who had surgery, respectively. The overall objective response rate was 71.7% after completion of chemotherapy. Based on Positron Emission Tomography Response Criteria in Solid Tumors using (18)F-fluorodeoxyglucose, complete metabolic response and partial metabolic response after 2-3 courses of nanoparticle albumin-bound paclitaxel were 15.1 and 52.8%, respectively. The most common significant toxicities of q3w nanoparticle albumin-bound paclitaxel were Grade 3 muscle pain, neuropathy and febrile neutropenia, each in 1 (1.9%) patient. There were no incidences of anaphylaxis or Grade 4/5 adverse events. Neoadjuvant chemotherapy using q3w nanoparticle albumin-bound paclitaxel followed by epirubicin and cyclophosphamide was feasible in breast cancer patients with acceptable clinical response and drug tolerance, but conferred a low rate of pathological complete response. Monotherapy with q3w nanoparticle albumin-bound paclitaxel could be an appropriate substitute for solvent-based taxane in

  17. Chlorine and temperature directed self-assembly of Mg-Ru2(ii,iii) carbonates and particle size dependent magnetic properties.

    PubMed

    Yang, Jian-Hui; Cheng, Ru-Mei; Jia, Yan-Yan; Jin, Jin; Yang, Bing-Bing; Cao, Zhi; Liu, Bin

    2016-02-21

    A series of heterometallic magnesium diruthenium(ii,iii) carbonates, namely K{Mg(H2O)6}2[Ru2(CO3)4Cl2]·4H2O (1), K2[{Mg(H2O)4}2Ru2(CO3)4(H2O)Cl]Cl2·2H2O (2), K[Mg(H2O)5Ru2(CO3)4]·5H2O (3) and K[Mg(H2O)4Ru2(CO3)4]·H2O (4), were synthesized from the reaction of Ru2(CO3)4(3-) and Mg(2+) in aqueous solution. Compound 1 is composed of ionic crystals with the Ru2(CO3)4Cl2(5-) : Mg(H2O)6(2+) : K(+) ratio of 1 : 2 : 1. Compound 2 consists of two dimensional layer structures, in which each octahedral environment Mg(H2O)4(2+) bonds to two [Ru2(CO3)4(H2O)Cl](4-) units in a cis manner forming a neutral square-grid layer {Mg(H2O)4Ru2(CO3)4(H2O)Cl}n. For compound 3, one water molecule of each Mg(H2O)6(2+) is substituted by an oxygen atom of Ru2(CO3)4(3-) forming [Mg(H2O)5Ru2(CO3)4](-), and then the neighboring Ru2 dimers are linked together by the rest of the two oxygen atoms of carbonates to form a layer structure {Mg(H2O)5Ru2(CO3)4}n(n-). In compound 4, the neighboring squared-grid layers {Ru2(CO3)4}n(3n-), similar to those in compound 3, are linked by each octahedral environment Mg(H2O)4(2+) in a cis manner forming the three-dimensional network {Mg(H2O)4Ru2(CO3)4}n(n-). Compound 3 shows ferromagnetic coupling between Ru2 dimers, and a long-range ordering is observed below 3.8 K. Compound 4 displays a magnetic ordering below 3.5 K, and a systematic study of the size-dependent magnetic properties of compound 4 reveals that the coercivity of 4 has been improved with reduced sample particle size from the micrometer to the nanometer scale.

  18. Docetaxel, cisplatin and 5-fluorouracil adjuvant chemotherapy following three-field lymph node dissection for stage II/III N1, 2 esophageal cancer.

    PubMed

    Hashiguchi, Tadasuke; Nasu, Motomi; Hashimoto, Takashi; Kuniyasu, Tetsuji; Inoue, Hirohumi; Sakai, Noritaka; Ouchi, Kazutomo; Amano, Takayuki; Isayama, Fuyumi; Tomita, Natsumi; Iwanuma, Yoshimi; Tsurumaru, Masahiko; Kajiyama, Yoshiaki

    2014-09-01

    To determine the efficacy of postoperative adjuvant chemotherapy with docetaxel + cisplatin + 5-fluorouracil (DCF) in lymph node metastasis-positive esophageal cancer, we retrospectively analyzed 139 patients with stage II/III (non-T4) esophageal cancer with lymph node metastasis (1-6 nodes), who did not receive preoperative treatment and underwent three-field lymph node dissection in the Juntendo University Hospital between December, 2004 and December, 2009. The tumors were histologically diagnossed as squamous cell carcinoma. The patients were divided into two groups, a surgery alone group (S group, 88 patients) and a group that received postoperative DCF therapy (DCF group, 51 patients). The disease-free and overall survival were compared between the groups and a multivariate analysis of prognostic factors was performed. The same analysis was performed for cases classified as N1 and N2, according to the TNM classification. There were no significant differences between the S and DCF groups regarding clinicopathological factors other than intramural metastasis and main tumor location. The presence of intramural metastasis, blood vessel invasion and the number of lymph nodes were identified as prognostic factors. The 5-year disease-free and overall survival were 55.8 and 57.3%, respectively, in the S group and 52.8 and 63.0%, respectively, in the DCF group. These differences were not considered to be statistically significant (P=0.789 and 0.479 for disease-free and overall survival, respectively). Although there were no significant differences in disease-free and overall survival between the S and DCF groups in N1 cases, both disease-free and overall survival were found to be better in the DCF group (54.2 and 61.4%, respectively) compared to the S group (29.6 and 28.8%, respectively) in N2 cases (P=0.029 and 0.020 for disease-free and overall survival, respectively). Therefore, postoperative adjuvant chemotherapy with DCF was shown to improve disease-free and

  19. SCOPE1: a randomised phase II/III multicentre clinical trial of definitive chemoradiation, with or without cetuximab, in carcinoma of the oesophagus

    PubMed Central

    2011-01-01

    Background Chemoradiotherapy is the standard of care for patients with oesophageal cancer unsuitable for surgery due to the presence of co-morbidity or extent of disease, and is a standard treatment option for patients with squamous cell carcinoma of the oesophagus. Modern regimens of chemoradiotherapy can lead to significant long-term survival. However the majority of patients will die of their disease, most commonly with local progression/recurrence of their tumours. Cetuximab may overcome one of the principal mechanisms of tumour radio-resistance, namely tumour repopulation, in patients treated with chemoradiotherapy. The purpose of this research is first to determine whether the addition of cetuximab to definitive chemoradiotherapy for treatment of patients with non-metastatic carcinoma of the oesophagus is active (in terms of failure-free rate), safe, and feasible within the context of a multi-centre randomised controlled trial in the UK. If the first stage is successful then the trial will continue to accrue sufficient patients to establish whether the addition of cetuximab to the standard treatment improves overall survival. Methods/Design SCOPE1 is a two arm, open, randomised multicentre Phase II/III trial. Eligible patients will have histologically confirmed carcinoma of the oesophagus and have been chosen to receive definitive chemoradiotherapy by an accredited multidisciplinary team including a specialist Upper GI surgeon. 420 patients will be randomised to receive definitive chemoradiotherapy with or without cetuximab using a 1:1 allocation ratio. During Phase II of the study, the trial will assess safety (toxicity), activity (failure-free rate) and feasibility (recruitment rate and protocol dose modifications/delays) in 90 patients in the experimental arm. If the experimental arm is found to be active, safe, and feasible by the Independent Data Monitoring Committee then recruitment will continue into Phase III. This second stage will recruit a further

  20. Potential methane production and oxidation in soil reclamation covers of an oil sands mining site in Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Pum, Lisa; Reichenauer, Thomas; Germida, Jim

    2015-04-01

    Anthropogenic activities create a number of significant greenhouse gases and thus potentially contribute to global warming. Methane production is significant in some agricultural production systems and from wetlands. In soil, methane can be oxidised by methanotrophic bacteria. However, little is known about methane production and oxidation in oil sand reclamation covers. The purpose of this study was to investigate methane production and oxidation potential of tailing sands and six different reclamation layers of oil sands mining sites in Alberta, Canada. Methane production and oxidation potential were investigated in laboratory scale microcosms through continuous headspace analysis using gas chromatography. Samples from a reclamation layer were collected at the Canadian Natural Resources Limited (CNRL) reclamation site at depths of 0-10 cm, 10-20 cm and 20-40 cm in October 2014. In addition, tailing sands provided by Suncor Energy Inc. and soil from a CNRL wetland were studied for methane production. Samples were dried, crushed and sieved to 4 mm, packed into serum bottle microcosms and monitored for eight weeks. Methane production potential was assessed by providing an anoxic environment and by adjusting the samples to a moisture holding capacity of 100 %. Methane oxidation potential was examined by an initial application of 2 vol % methane to the microcosms and by adjusting the samples to a moisture holding capacity of 50 %. Microcosm headspace gas was analysed for methane, carbon dioxide, nitrous oxide and oxygen. All experiments were carried out in triplicates, including controls. SF6 and Helium were used as internal standards to detect potential leaks. Our results show differences for methane production potential between the soil depths, tailing sands and wetlands. Moreover, there were differences in the methane oxidation potential of substrate from the three depths investigated and between the reclamation layers. In conclusion, the present study shows that

  1. Genetic toxicology and preliminary in vivo studies of nitric oxide donor tocopherol analogs as potential new class of antiatherogenic agents.

    PubMed

    Cabrera, Mauricio; López, Gloria V; Gómez, Luis E; Breijo, Martín; Pintos, Cristina; Botti, Horacio; Raymondo, Stella; Vettorazzi, Ariane; Ceráin, Adela López de; Monge, Antonio; Rubbo, Homero; González, Mercedes; Cerecetto, Hugo

    2011-07-01

    Nitric oxide donor tocopherol analogs were found to be incorporated in low-density lipoprotein to release nitric oxide into the hydrophobic core of the lipoprotein, thus inhibiting lipid oxidation processes associated with atheroma plaque formation. Previously, we studied their cytotoxicity against human and murine macrophages as first selection for in vivo studies. Herein, we examined both the in vitro mutagenic and DNA-damage effects of selected compounds to further evaluate drug potential. While the compounds of interest were nongenotoxics in both experimental tests (Ames and alkaline comet), one of the potential blood metabolites exhibited genotoxicity (alkaline comet test), and the furazan derivative was mutagenic (Ames test). Two selected (nitrooxy and furoxan) compounds were studied in long- and short-term in vivo treatment, and in these conditions, animal toxicity was not evidenced, suggesting the possibility of these compounds as potential antiatherogenic drugs.

  2. High-Potential Electrocatalytic O2 Reduction with Nitroxyl / NOx Mediators: Implications for Fuel Cells and Aerobic Oxidation Catalysis

    SciTech Connect

    Gerken, James B.; Stahl, Shannon S.

    2015-07-15

    Efficient reduction of O2 to water is a central challenge in energy conversion and aerobic oxidation catalysis. In the present study, we investigate the electrochemical reduction of O2 with soluble organic nitroxyl and nitrogen oxide (NOx) mediators. When used alone, neither organic nitroxyls, such as TEMPO (2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl), nor NOx species, such as sodium nitrite, are effective mediators of electrochemical O2 reduction. The combination of nitroxyl/NOx species, however, mediates sustained O2 reduction at electrochemical potentials of 0.19–0.33 V (vs. Fc/Fc+) in acetonitrile containing trifluoroacetic acid. Mechanistic analysis of the coupled redox reactions supports a process in which the nitrogen oxide catalyst drives aerobic oxidation of a nitroxyl mediator to an oxoammonium species, which then is reduced back to the nitroxyl at the cathode. The electrolysis potential is dictated by the oxoammonium/nitroxyl reduction potential. The high potentials observed with this ORR system benefit from the mechanism-based specificity for four-electron reduction of oxygen to water mediated by NOx species, together with kinetically efficient reduction of oxidized NOx species by TEMPO and other organic nitroxyls. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

  3. Hypotheses on the Potential of Rice Bran Intake to Prevent Gastrointestinal Cancer through the Modulation of Oxidative Stress

    PubMed Central

    Law, Bernard M. H.; Waye, Mary M. Y.; So, Winnie K. W.; Chair, Sek Ying

    2017-01-01

    Previous studies have suggested the potential involvement of oxidative stress in gastrointestinal cancers. In light of this, research efforts have been focused on the potential of dietary antioxidant intake to prevent gastrointestinal cancer through the modulation of oxidative stress. Rice bran, a by-product of rice milling, has been shown to contain an abundance of phytochemicals, which are dietary antioxidants. To date, a number of studies have shown the antioxidative effect of rice bran intake, and some demonstrated that such an effect may contribute to gastrointestinal cancer prevention, largely through the antioxidative properties of rice bran phytochemicals. In addition, these phytochemicals were shown to provide protection against cancer through mechanisms linked to oxidative stress, including β-catenin-mediated cell proliferation and inflammation. The present article provides an overview of current evidence for the antioxidative properties of rice bran and its phytochemicals, and for the potential of such properties in cancer prevention through the oxidative-stress-linked mechanisms mentioned above. The article also highlights the need for an evaluation of the effectiveness of rice bran dietary interventions among cancer survivors in ameliorating oxidative stress and reducing the level of gastrointestinal cancer biomarkers, thereby establishing the potential of such interventions among these individuals in the prevention of cancer recurrence. PMID:28672811

  4. Protein oxidation: examination of potential lipid-independent mechanisms for protein carbonyl formation.

    PubMed

    Blakeman, D P; Ryan, T P; Jolly, R A; Petry, T W

    1998-01-01

    Previous data indicated that diquat-mediated protein oxidation (protein carbonyl formation) occurs through multiple pathways, one of which is lipid dependent, and the other, lipid independent. Studies reported here investigated potential mechanisms of the lipid-independent pathway in greater detail, using bovine serum albumin as the target protein. One hypothesized mechanism of protein carbonyl formation involved diquat-dependent production of H2O2, which would then react with site-specifically bound ferrous iron as proposed by Stadtman and colleagues. This hypothesis was supported by the inhibitory effect of catalase on diquat-mediated protein carbonyl formation. However, exogenous H2O2 alone did not induce protein carbonyl formation. Hydroxyl radical-generating reactions may result from the H2O2-catalyzed oxidation of ferrous iron, which normally is bound to protein in the ferric state. Therefore, the possible reduction of site-specifically bound Fe3+ to Fe2+ by the diquat cation radical (which could then react with H2O2) was also investigated. The combination of H2O2 and an iron reductant, ascorbate, however, also failed to induce significant protein carbonyl formation. In a phospholipid-containing system, an ADP:Fe2+ complex induced both lipid peroxidation and protein carbonyl formation; both indices were largely inhibitable by antioxidants. There was no substantial ADP:Fe(2+)-dependent protein carbonyl formation in the absence of phospholipid under otherwise identical conditions. Based on the lipid requirement and antioxidant sensitivity, these data suggest that ADP:Fe(2+)-dependent protein carbonyl formation occurs through reaction of BSA with aldehydic lipid peroxidation products. The precise mechanism of diquat-mediated protein carbonyl formation remains unclear, but it appears not to be a function of H2O2 generation or diquat cation radical-dependent reduction of bound Fe3+.

  5. Iron oxide nanoparticles functionalized with novel hydrophobic and hydrophilic porphyrins as potential agents for photodynamic therapy.

    PubMed

    Penon, Oriol; Marín, María J; Amabilino, David B; Russell, David A; Pérez-García, Lluïsa

    2016-01-15

    The preparation of novel porphyrin derivatives and their immobilization onto iron oxide nanoparticles to build up suitable nanotools for potential use in photodynamic therapy (PDT) has been explored. To achieve this purpose, a zinc porphyrin derivative, ZnPR-COOH, has been synthesized, characterized at the molecular level and immobilized onto previously synthesized iron oxide nanoparticles covered with oleylamine. The novel nanosystem (ZnPR-IONP) has been thoroughly characterized by a variety of techniques such as UV-Vis absorption spectroscopy, fluorescence spectroscopy, X-ray photoloectron spectroscopy (XPS) and transmission electron microscopy (TEM). In order to probe the capability of the photosensitizer for PDT, the singlet oxygen production of both ZnPR-IONP and the free ligand ZnPR-COOH have been quantified by measuring the decay in absorption of the anthracene derivative 9,10-anthracenedipropionic acid (ADPA), showing an important increase on singlet oxygen production when the porphyrin is incorporated onto the IONP (ZnPR-IONP). On the other hand, the porphyrin derivative PR-TRIS3OH, incorporating several polar groups (TRIS), was synthesized and immobilized with the intention of obtaining water soluble nanosystems (PR-TRIS-IONP). When the singlet oxygen production ability was evaluated, the values obtained were similar to ZnPR-COOH/ZnPR-IONP, again much higher in the case of the nanoparticles PR-TRIS-IONP, with more than a twofold increase. The efficient singlet oxygen production of PR-TRIS-IONP together with their water solubility, points to the great promise that these new nanotools represent for PDT. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Methane oxidation potential of boreal landfill cover materials: The governing factors and enhancement by nutrient manipulation.

    PubMed

    Maanoja, Susanna T; Rintala, Jukka A

    2015-12-01

    Methanotrophs inhabiting landfill covers are in a crucial role in mitigating CH4 emissions, but the characteristics of the cover material or ambient temperature do not always enable the maximal CH4 oxidation potential (MOP). This study aimed at identifying the factors governing MOPs of different materials used for constructing biocovers and other cover structures. We also tested whether the activity of methanotrophs could be enhanced at cold temperature (4 and 12°C) by improving the nutrient content (NO3(-), PO4(3-), trace elements) of the cover material. Compost samples from biocovers designed to support CH4 oxidation were exhibiting the highest MOPs (4.16 μmol CH4 g dw(-1) h(-1)), but also the soil samples collected from other cover structures were oxidising CH4 (0.41 μmol CH4 g dw(-1) h(-1)). The best predictors for the MOPs were the NO3(-) content and activity of heterotrophic bacteria at 72.8%, which were higher in the compost samples than in the soil samples. The depletion of NO3(-) from the landfill cover material limiting the activity of methanotrophs could not be confirmed by the nutrient manipulation assay at 4°C as the addition of nitrogen decreased the MOPs from 0.090 μmol CH4 g dw(-1) h(-1) to <0.085 μmol CH4 g dw(-1) h(-1). At 12°C, all nutrient additions reduced the MOPs. The inhibition was believed to result from high ionic concentration caused by nutrient addition. At 4°C, the addition of trace elements increased the MOPs (>0.096 μmol CH4 g dw(-1)h(-1)) suggesting that this was attributable to stimulation of the enzymatic activity of the psychrotolerant methanotrophs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Exposure to PM2.5 in modern office buildings through elemental characterization and oxidative potential

    NASA Astrophysics Data System (ADS)

    Szigeti, Tamás; Kertész, Zsófia; Dunster, Christina; Kelly, Frank J.; Záray, Gyula; Mihucz, Victor G.

    2014-09-01

    Fifty samples of indoor and outdoor PM2.5 were collected onto quartz fiber and Teflon membrane filters in five office buildings equipped with heating, ventilation and air-conditioning system for 8 h daily in order to coincide with the work shift of employees. Samples were analyzed for i) mass concentration; ii) elemental concentration; and iii) oxidative potential (OP) through antioxidant depletion. The PM2.5 mass concentration exceeded the annual mean guideline of 10 μg m-3 WHO in 50% of the samples. Indoor and outdoor PM2.5 mass concentrations correlated almost linearly. Proton-induced X-ray emission (PIXE) spectrometry was used for the monitoring of 21 elements. Quantitative determination was achieved in the case of Teflon filters only for Al, Si, S, Cl, K, Ca, Ti, Cr, Mn, Fe and Zn at ng m-3 concentration level. Quartz fiber filters were less adequate for the PIXE measurements due to their greater thickness and filamentary structure. Ca, Cr, Zn and Ti had generally higher concentration (mg g-1) indoors. Indoor/outdoor (I/O) OP values were higher than one in 14% and 57% of the samples in the case of ascorbate and reduced glutathione (GSH), respectively. Spatial and temporal variations of OP were observed across the office buildings. The I/O ratios for OP, Cr and Zn concentrations in the case of GSH were higher for three buildings. Significant relationship was observed between GSH oxidation and Cr and Zn concentrations. Thus, employees were exposed to a higher extent to reactive oxygen species in three buildings.

  8. Oxidative species-induced excitonic transport in tubulin aromatic networks: Potential implications for neurodegenerative disease.

    PubMed

    Kurian, P; Obisesan, T O; Craddock, T J A

    2017-10-01

    Oxidative stress is a pathological hallmark of neurodegenerative tauopathic disorders such as Alzheimer's disease and Parkinson's disease-related dementia, which are characterized by altered forms of the microtubule-associated protein (MAP) tau. MAP tau is a key protein in stabilizing the microtubule architecture that regulates neuron morphology and synaptic strength. When MAP tau is degraded in tauopathic disorders, neuron dysfunction results. The precise role of reactive oxygen species (ROS) in the tauopathic disease process, however, is poorly understood. Classically, mitochondrial dysfunction has been viewed as the major source of oxidative stress and has been shown to precede tau and amyloid pathology in various dementias, but the exact mechanisms are not clear. It is known that the production of ROS by mitochondria can result in ultraweak photon emission (UPE) within cells. While of low intensity, surrounding proteins within the cytosol can still absorb these energetic photons via aromatic amino acids (e.g., tryptophan and tyrosine). One likely absorber of these photons is the microtubule cytoskeleton, as it forms a vast network spanning neurons, is highly co-localized with mitochondria, and shows a high density of aromatic amino acids. Functional microtubule networks may traffic this ROS-generated endogenous photon energy for cellular signaling, or they may serve as dissipaters/conduits of such energy to protect the cell from potentially harmful effects. Experimentally, after in vitro exposure to exogenous photons, microtubules have been shown to reorient and reorganize in a dose-dependent manner with the greatest effect being observed around 280nm, in the tryptophan and tyrosine absorption range. In this paper, recent modeling efforts based on ambient temperature experiment are presented, showing that tubulin polymers can feasibly absorb and channel these photoexcitations via resonance energy transfer, on the order of dendritic length scales and neuronal

  9. Nox2 as a potential target of mitochondrial superoxide and its role in endothelial oxidative stress

    PubMed Central

    Nazarewicz, Rafal R.; Bikineyeva, Alfiya; Dikalov, Sergey I.

    2013-01-01

    Superoxide (O2·−) production by the NADPH oxidases is implicated in the pathogenesis of many cardiovascular diseases, including hypertension. We have previously shown that activation of NADPH oxidases increases mitochondrial O2·− which is inhibited by the ATP-sensitive K+ channel (mitoKATP) inhibitor 5-hydroxydecanoic acid and that scavenging of mitochondrial or cytoplasmic O2·− inhibits hypertension. We hypothesized that mitoKATP-mediated mitochondrial O2·− potentiates cytoplasmic O2·− by stimulation of NADPH oxidases. In this work we studied Nox isoforms as a potential target of mitochondrial O2·−. We tested contribution of reverse electron transfer (RET) from complex II to complex I in mitochondrial O2·− production and NADPH oxidase activation in human aortic endothelial cells. Activation of mitoKATP with low dose of diazoxide (100 nM) decreased mitochondrial membrane potential (tetramethylrhodamine methyl ester probe) and increased production of mitochondrial and cytoplasmic O2·− measured by site-specific probes and mitoSOX. Inhibition of RET with complex II inhibitor (malonate) or complex I inhibitor (rotenone) attenuated the production of mitochondrial and cytoplasmic O2·−. Supplementation with a mitochondria-targeted SOD mimetic (mitoTEMPO) or a mitochondria-targeted glutathione peroxidase mimetic (mitoEbselen) inhibited production of mitochondrial and cytoplasmic O2·−. Inhibition of Nox2 (gp91ds) or Nox2 depletion with small interfering RNA but not Nox1, Nox4, or Nox5 abolished diazoxide-induced O2·− production in the cytoplasm. Treatment of angiotensin II-infused mice with RET inhibitor dihydroethidium (malate) significantly reduced blood pressure. Our study suggests that mitoKATP-mediated mitochondrial O2·− stimulates cytoplasmic Nox2, contributing to the development of endothelial oxidative stress and hypertension. PMID:23955717

  10. Development of a ReaxFF potential for Pd/O and application to palladium oxide formation

    NASA Astrophysics Data System (ADS)

    Senftle, Thomas P.; Meyer, Randall J.; Janik, Michael J.; van Duin, Adri C. T.

    2013-07-01

    Oxide formation on palladium surfaces impacts the activity and selectivity of Pd-based catalysts, which are widely employed under oxygen rich operating conditions. To investigate oxidation processes over Pd catalysts at time and length scales inaccessible to quantum based computational methods, we have developed a Pd/O interaction potential for the ReaxFF reactive force field. The parameters of the ReaxFF potential were fit against an extensive set of quantum data for both bulk and surface properties. Using the resulting potential, we conducted molecular dynamics simulations of oxide formation on Pd(111), Pd(110), and Pd(100) surfaces. The results demonstrate good agreement with previous experimental observations; oxygen diffusion from the surface to the subsurface occurs faster on the Pd(110) surface than on the Pd(111) and Pd(100) surfaces under comparable conditions at high temperatures and pressures. Additionally, we developed a ReaxFF-based hybrid grand canonical Monte Carlo/molecular dynamics (GC-MC/MD) approach to assess the thermodynamic stability of oxide formations. This method is used to derive a theoretical phase diagram for the oxidation of Pd935 clusters in temperatures ranging from 300 K to 1300 K and oxygen pressures ranging from 10-14 atm to 1 atm. We observe good agreement between experiment and ReaxFF, which validates the Pd/O interaction potential and demonstrates the feasibility of the hybrid GC-MC/MD method for deriving theoretical phase diagrams. This GC-MC/MD method is novel to ReaxFF, and is well suited to studies of supported-metal-oxide catalysts, where the extent of oxidation in metal clusters can significantly influence catalytic activity, selectivity, and stability.

  11. Pharmacology and potential therapeutic applications of nitric oxide-releasing non-steroidal anti-inflammatory and related nitric oxide-donating drugs

    PubMed Central

    Keeble, J E; Moore, P K

    2002-01-01

    This review examines the biological significance, therapeutic potential and mechanism(s) of action of a range of nitric oxide-releasing non-steroidal anti-inflammatory drugs (NO-NSAID) and related nitric oxide-releasing donating drugs (NODD). The slow release of nitric oxide (NO) from these compounds leads to subtle changes in the profile of pharmacological activity of the parent, non-steroidal anti-inflammatory drugs (NSAID). For example, compared with NSAID, NO-NSAID cause markedly diminished gastrointestinal toxicity and improved anti-inflammatory and anti-nociceptive efficacy. In addition, nitroparacetamol exhibits hepatoprotection as opposed to the hepatotoxic activity of paracetamol. The possibility that NO-NSAID or NODD may be of therapeutic benefit in a wide variety of disease states including pain and inflammation, thrombosis and restenosis, neurodegenerative diseases of the central nervous system, colitis, cancer, urinary incontinence, liver disease, impotence, bronchial asthma and osteoporosis is discussed. PMID:12237248

  12. Polyol synthesis, functionalisation, and biocompatibility studies of superparamagnetic iron oxide nanoparticles as potential MRI contrast agents

    NASA Astrophysics Data System (ADS)

    Hachani, Roxanne; Lowdell, Mark; Birchall, Martin; Hervault, Aziliz; Mertz, Damien; Begin-Colin, Sylvie; Thanh, Nguy&Ecirtil; N. Thi&Cmb. B. Dot; Kim

    2016-02-01

    Iron oxide nanoparticles (IONPs) of low polydispersity were obtained through a simple polyol synthesis in high pressure and high temperature conditions. The control of the size and morphology of the nanoparticles was studied by varying the solvent used, the amount of iron precursor and the reaction time. Compared with conventional synthesis methods such as thermal decomposition or co-precipitation, this process yields nanoparticles with a narrow particle size distribution in a simple, reproducible and cost effective manner without the need for an inert atmosphere. For example, IONPs with a diameter of ca. 8 nm could be made in a reproducible manner and with good crystallinity as evidenced by X-ray diffraction analysis and high saturation magnetization value (84.5 emu g-1). The surface of the IONPs could be tailored post synthesis with two different ligands which provided functionality and stability in water and phosphate buffer saline (PBS). Their potential as a magnetic resonance imaging (MRI) contrast agent was confirmed as they exhibited high r1 and r2 relaxivities of 7.95 mM-1 s-1 and 185.58 mM-1 s-1 respectively at 1.4 T. Biocompatibility and viability of IONPs in primary human mesenchymal stem cells (hMSCs) was studied and confirmed.Iron oxide nanoparticles (IONPs) of low polydispersity were obtained through a simple polyol synthesis in high pressure and high temperature conditions. The control of the size and morphology of the nanoparticles was studied by varying the solvent used, the amount of iron precursor and the reaction time. Compared with conventional synthesis methods such as thermal decomposition or co-precipitation, this process yields nanoparticles with a narrow particle size distribution in a simple, reproducible and cost effective manner without the need for an inert atmosphere. For example, IONPs with a diameter of ca. 8 nm could be made in a reproducible manner and with good crystallinity as evidenced by X-ray diffraction analysis and high

  13. Influence of oxic/anoxic fluctuations on ammonia oxidizers and nitrification potential in a wet tropical soil.

    PubMed

    Pett-Ridge, Jennifer; Petersen, Dorthe G; Nuccio, Erin; Firestone, Mary K

    2013-07-01

    Ammonia oxidation is a key process in the global nitrogen cycle. However, in tropical soils, little is known about ammonia-oxidizing microorganisms and how characteristically variable oxygen regimes affect their activity. We investigated the influence of brief anaerobic periods on ammonia oxidation along an elevation, moisture, and oxygen availability gradient in wet tropical soils. Soils from three forest types were incubated for up to 36 weeks in lab microcosms under three regimes: (1) static aerobic; (2) static anaerobic; and (3) fluctuating (aerobic/anaerobic). Nitrification potential was measured in field-fresh soils and incubated soils. The native ammonia-oxidizing community was also characterized, based on diversity assessments (clone libraries) and quantification of the ammonia monooxygenase α-subunit (amoA) gene. These relatively low pH soils appear to be dominated by ammonia-oxidizing archaea (AOA), and AOA communities in the three soil types differed significantly in their ability to oxidize ammonia. Soils from an intermediate elevation, and those incubated with fluctuating redox conditions, tended to have the highest nitrification potential following an influx of oxygen, although all soils retained the capacity to nitrify even after long anoxic periods. Together, these results suggest that wet tropical soil AOA are tolerant of extended periods of anoxia.

  14. The Loss Of Macrophage Fatty Acid Oxidation Does Not Potentiate Systemic Metabolic Dysfunction.

    PubMed

    Gonzalez-Hurtado, Elsie; Lee, Jieun; Choi, Joseph; Selen Alpergin, Ebru S; Collins, Samuel L; Horton, Maureen R; Wolfgang, Michael J

    2017-02-21

    Fatty acid oxidation in macrophages has been suggested to play a causative role in high-fat diet-induced metabolic dysfunction, particularly in the etiology of adipose driven insulin resistance. To understand the contribution of macrophage fatty acid oxidation directly to metabolic dysfunction in high-fat diet-induced obesity, we generated mice with a myeloid-specific knockout of carnitine palmitoyltransferase 2 (CPT2 Mϕ-KO), an obligate step in mitochondrial long-chain fatty acid oxidation. While fatty acid oxidation was clearly induced upon IL-4 stimulation, fatty acid oxidation deficient CPT2 Mϕ-KO bone marrow derived macrophages (BMDM) displayed canonical markers of M2 polarization following IL-4 stimulation in vitro. In addition, loss of macrophage fatty acid oxidation in vivo did not alter the progression of high-fat diet induced obesity, inflammation, macrophage polarization, oxidative stress, or glucose intolerance. These data suggest that although alternatively activated macrophages up-regulate fatty acid oxidation, fatty acid oxidation is dispensable for macrophage polarization and high-fat diet-induced metabolic dysfunction. Macrophage fatty acid oxidation likely plays a correlative rather than causative role in systemic metabolic dysfunction.

  15. High-Potential Electrocatalytic O2 Reduction with Nitroxyl/NOx Mediators: Implications for Fuel Cells and Aerobic Oxidation Catalysis

    PubMed Central

    2015-01-01

    Efficient reduction of O2 to water is a central challenge in energy conversion and many aerobic oxidation reactions. Here, we show that the electrochemical oxygen reduction reaction (ORR) can be achieved at high potentials by using soluble organic nitroxyl and nitrogen oxide (NOx) mediators. When used alone, neither organic nitroxyls, such as 2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl (TEMPO), nor NOx species, such as sodium nitrite, are effective ORR mediators. The combination of nitroxyl/NOx species, however, mediates sustained O2 reduction with overpotentials as low as 300 mV in acetonitrile containing trifluoroacetic acid. Mechanistic analysis of the coupled redox reactions supports a process in which the nitrogen oxide catalyst drives aerobic oxidation of a nitroxyl mediator to an oxoammonium species, which then is reduced back to the nitroxyl at the cathode. The electrolysis potential is dictated by the oxoammonium/nitroxyl reduction potential. The overpotentials accessible with this ORR system are significantly lower than widely studied molecular metal-macrocycle ORR catalysts and benefit from the mechanism-based specificity for four-electron reduction of oxygen to water mediated by NOx species, together with kinetically efficient reduction of oxidized NOx species by TEMPO and other organic nitroxyls. PMID:27162977

  16. Abundance, distribution and potential activity of methane oxidizing bacteria in permafrost soils from the Lena Delta, Siberia.

    PubMed

    Liebner, Susanne; Wagner, Dirk

    2007-01-01

    The methane oxidation potential of active layer profiles of permafrost soils from the Lena Delta, Siberia, was studied with regard to its respond to temperature, and abundance and distribution of type I and type II methanotrophs. Our results indicate vertical shifts within the optimal methane oxidation temperature and within the distribution of type I and type II methanotrophs. In the upper active layer, maximum methane oxidation potentials were detected at 21 degrees C. Deep active layer zones that are constantly exposed to temperatures below 2 degrees C showed a maximum potential to oxidize methane at 4 degrees C. Our results indicate a dominance of psychrophilic methanotrophs close to the permafrost table. Type I methanotrophs dominated throughout the active layer profiles but their number strongly fluctuated with depth. In contrast, type II methanotrophs were constantly abundant through the whole active layer and displaced type I methanotrophs close to the permafrost table. No correlation between in situ temperatures and the distribution of type I and type II methanotrophs was found. However, the distribution of type I and type II methanotrophs correlated significantly with in situ methane concentrations. Beside vertical fluctuations, the abundance of methane oxidizers also fluctuated according to different geomorphic units. Similar methanotroph cell counts were detected in samples of a flood plain and a polygon rim, whereas cell counts in samples of a polygon centre were up to 100 times lower.

  17. YC-1 potentiates cAMP-induced CREB activation and nitric oxide production in alveolar macrophages

    SciTech Connect

    Hwang, Tsong-Long; Tang, Ming-Chi; Kuo, Liang-Mou; Chang, Wen-De; Chung, Pei-Jen; Chang, Ya-Wen; Fang, Yao-Ching

    2012-04-15

    Alveolar macrophages play significant roles in the pathogenesis of several inflammatory lung diseases. Increases in exhaled nitric oxide (NO) are well documented to reflect disease severity in the airway. In this study, we investigated the effect of 3-(5′-hydroxymethyl-2′-furyl)-1-benzyl indazole (YC-1), a known activator of soluble guanylyl cyclase, on prostaglandin (PG)E{sub 1} (a stable PGE{sub 2} analogue) and forskolin (a adenylate cyclase activator) induced NO production and inducible NO synthase (iNOS) expression in rat alveolar macrophages (NR8383). YC-1 did not directly cause NO production or iNOS expression, but drastically potentiated PGE{sub 1}- or forskolin-induced NO production and iNOS expression in NR8383 alveolar macrophages. Combination treatment with YC-1 and PGE{sub 1} significantly increased phosphorylation of the cAMP response element-binding protein (CREB), but not nuclear factor (NF)-κB activation. The combined effect on NO production, iNOS expression, and CREB phosphorylation was reversed by a protein kinase (PK)A inhibitor (H89), suggesting that the potentiating functions were mediated through a cAMP/PKA signaling pathway. Consistent with this, cAMP analogues, but not the cGMP analogue, caused NO release, iNOS expression, and CREB activation. YC-1 treatment induced an increase in PGE{sub 1}-induced cAMP formation, which occurred through the inhibition of cAMP-specific phosphodiesterase (PDE) activity. Furthermore, the combination of rolipram (an inhibitor of PDE4), but not milronone (an inhibitor of PDE3), and PGE{sub 1} also triggered NO production and iNOS expression. In summary, YC-1 potentiates PGE{sub 1}-induced NO production and iNOS expression in alveolar macrophages through inhibition of cAMP PDE activity and activation of the cAMP/PKA/CREB signaling pathway. Highlights: ► YC-1 potentiated PGE1-induced iNOS expression in alveolar macrophages. ► The combination of YC-1 and PGE1 increased CREB but not NFκB activation.

  18. Inhibition of ornithine decarboxylase potentiates nitric oxide production in LPS-activated J774 cells

    PubMed Central

    Baydoun, Anwar R; Morgan, David M L

    1998-01-01

    We have examined whether modulation of the polyamine biosynthetic pathway, through inhibition by α-difluoromethylornithine (DFMO) of the rate limiting enzyme, ornithine decarboxylase (ODC), modulates NO synthesis in J774 macrophages.DFMO potentiated LPS-stimulated nitrite production in both a concentration- and time-dependent manner, increasing nitrite levels by 48±5% at 10 mM. This effect was observed in cells pre-treated with DFMO for 24 h prior to stimulation with LPS. Addition of DFMO 12 h after LPS failed to potentiate LPS-induced nitrite production.Supplementation of the culture medium with horse serum (10%) in place of foetal calf serum (10%) caused no significant change in either LPS-induced nitrite production or in the ability of DFMO (10  mM) to potentiate LPS-induced NO synthesis.Metabolism of L-[3H]arginine to L-[3H]citrulline by partially purified inducible nitric oxide synthase (iNOS) was not significantly altered by either DFMO (1–10 mM) or by putrescine (0.001–1 mM), spermidine (0.001–1 mM) or spermine (0.001–1 mM). iNOS activity was also unaffected by 1 mM EGTA but was markedly attenuated (70±0.07%) by L-NMMA (100 μM).Pre-incubation of cells with DFMO (10 mM; 24 h) prior to activation with LPS resulted in enhanced (∼2 fold) iNOS protein expression.These results show that DFMO potentiates LPS-induced nitrite production in the murine macrophage cell line J774. Since the only known mechanism of action of DFMO is inhibition of ODC, and thus polyamine biosynthesis, we conclude that expression of iNOS can be critically regulated by endogenous polyamines. PMID:9884080

  19. Assessment of the toxic potential of engineered metal oxide nanomaterials using an acellular model: citrated rat blood plasma.

    PubMed

    Gormley, Patrick Thomas; Callaghan, Neal Ingraham; MacCormack, Tyson James; Dieni, Christopher Anthony

    2016-10-01

    Citrated Sprague-Dawley rat blood plasma was used as a biologically relevant exposure medium to assess the acellular toxic potential of two metal oxide engineered nanomaterials (ENMs), zinc oxide (nZnO), and cerium oxide (nCeO2). Plasma was incubated at 37 °C for up to 48 h with ENM concentrations ranging between 0 and 200 mg/L. The degree of ENM-induced oxidation was assessed by assaying for reactive oxygen species (ROS) levels using dichlorofluorescein (DCF), pH, ferric reducing ability of plasma (FRAP), lipase activity, malondialdehyde (MDA), and protein carbonyls (PC). Whereas previous in vitro studies showed linear-positive correlations between ENM concentration and oxidative damage, our results suggested that low concentrations were generally pro-oxidant and higher concentrations appeared antioxidant or protective, as indicated by DCF fluorescence trends. nZnO and nCeO2 also affected pH in a manner dependent on concentration and elemental composition; higher nZnO concentrations maintained a more alkaline pH, while nCeO2 tended to decrease pH. No other biomarkers of oxidative damage (FRAP, MDA, PC, lipase activity) showed changes at any ENM concentration or time-point tested. Differential dissolution of the two ENMs was also observed, where as much as ∼31.3% of nZnO was instantaneously dissolved to Zn(2+ )and only negligible nCeO2 was degraded. The results suggest that the direct oxidative potential of nZnO and nCeO2 in citrated rat blood plasma is low, and that a physiological or immune response is needed to generate appreciable damage biomarkers. The data also highlight the need for careful consideration when selecting a model for assessing ENM toxicity.

  20. Particle emissions from microalgae biodiesel combustion and their relative oxidative potential.

    PubMed

    Rahman, M M; Stevanovic, S; Islam, M A; Heimann, K; Nabi, M N; Thomas, G; Feng, B; Brown, R J; Ristovski, Z D

    2015-09-01

    Microalgae are considered to be one of the most viable biodiesel feedstocks for the future due to their potential for providing economical, sustainable and cleaner alternatives to petroleum diesel. This study investigated the particle emissions from a commercially cultured microalgae and higher plant biodiesels at different blending ratios. With a high amount of long carbon chain lengths fatty acid methyl esters (C20 to C22), the microalgal biodiesel used had a vastly different average carbon chain length and level of unsaturation to conventional biodiesel, which significantly influenced particle emissions. Smaller blend percentages showed a larger reduction in particle emission than blend percentages of over 20%. This was due to the formation of a significant nucleation mode for the higher blends. In addition measurements of reactive oxygen species (ROS), showed that the oxidative potential of particles emitted from the microalgal biodiesel combustion were lower than that of regular diesel. Biodiesel oxygen content was less effective in suppressing particle emissions for biodiesels containing a high amount of polyunsaturated C20-C22 fatty acid methyl esters and generated significantly increased nucleation mode particle emissions. The observed increase in nucleation mode particle emission is postulated to be caused by very low volatility, high boiling point and high density, viscosity and surface tension of the microalgal biodiesel tested here. Therefore, in order to achieve similar PM (particulate matter) emission benefits for microalgal biodiesel likewise to conventional biodiesel, fatty acid methyl esters (FAMEs) with high amounts of polyunsaturated long-chain fatty acids (≥C20) may not be desirable in microalgal biodiesel composition.

  1. Dynamics of ammonia-oxidizing archaea and bacteria populations and contributions to soil nitrification potentials

    PubMed Central

    Taylor, Anne E; Zeglin, Lydia H; Wanzek, Thomas A; Myrold, David D; Bottomley, Peter J

    2012-01-01

    It is well known that the ratio of ammonia-oxidizing archaea (AOA) and bacteria (AOB) ranges widely in soils, but no data exist on what might influence this ratio, its dynamism, or how changes in relative abundance influences the potential contributions of AOA and AOB to soil nitrification. By sampling intensively from cropped-to-fallowed and fallowed-to-cropped phases of a 2-year wheat/fallow cycle, and adjacent uncultivated long-term fallowed land over a 15-month period in 2010 and 2011, evidence was obtained for seasonal and cropping phase effects on the soil nitrification potential (NP), and on the relative contributions of AOA and AOB to the NP that recovers after acetylene inactivation in the presence and absence of bacterial protein synthesis inhibitors. AOB community composition changed significantly (P⩽0.0001) in response to cropping phase, and there were both seasonal and cropping phase effects on the amoA gene copy numbers of AOA and AOB. Our study showed that the AOA:AOB shifts were generated by a combination of different phenomena: an increase in AOA amoA abundance in unfertilized treatments, compared with their AOA counterparts in the N-fertilized treatment; a larger population of AOB under the N-fertilized treatment compared with the AOB community under unfertilized treatments; and better overall persistence of AOA than AOB in the unfertilized treatments. These data illustrate the complexity of the factors that likely influence the relative contributions of AOA and AOB to nitrification under the various combinations of soil conditions and NH4+-availability that exist in the field. PMID:22695861

  2. Dynamics of ammonia-oxidizing archaea and bacteria populations and contributions to soil nitrification potentials.

    PubMed

    Taylor, Anne E; Zeglin, Lydia H; Wanzek, Thomas A; Myrold, David D; Bottomley, Peter J

    2012-11-01

    It is well known that the ratio of ammonia-oxidizing archaea (AOA) and bacteria (AOB) ranges widely in soils, but no data exist on what might influence this ratio, its dynamism, or how changes in relative abundance influences the potential contributions of AOA and AOB to soil nitrification. By sampling intensively from cropped-to-fallowed and fallowed-to-cropped phases of a 2-year wheat/fallow cycle, and adjacent uncultivated long-term fallowed land over a 15-month period in 2010 and 2011, evidence was obtained for seasonal and cropping phase effects on the soil nitrification potential (NP), and on the relative contributions of AOA and AOB to the NP that recovers after acetylene inactivation in the presence and absence of bacterial protein synthesis inhibitors. AOB community composition changed significantly (P0.0001) in response to cropping phase, and there were both seasonal and cropping phase effects on the amoA gene copy numbers of AOA and AOB. Our study showed that the AOA:AOB shifts were generated by a combination of different phenomena: an increase in AOA amoA abundance in unfertilized treatments, compared with their AOA counterparts in the N-fertilized treatment; a larger population of AOB under the N-fertilized treatment compared with the AOB community under unfertilized treatments; and better overall persistence of AOA than AOB in the unfertilized treatments. These data illustrate the complexity of the factors that likely influence the relative contributions of AOA and AOB to nitrification under the various combinations of soil conditions and NH(4)(+)-availability that exist in the field.

  3. Photocontrolled nitric oxide release from two nitrosylruthenium isomer complexes and their potential biomedical applications

    NASA Astrophysics Data System (ADS)

    Liu, Jiao; Duan, Qingqing; Wang, Jianru; Song, Zhen; Qiao, Xiaoyan; Wang, Hongfei

    2015-01-01

    Nitric oxide (NO) has key regulatory roles in various biological and medical processes. The control of its local concentration, which is crucial for obtaining the desired effect, can be achieved with exogenous NO donors. Release of NO from metal-nitrosyl complexes upon exposure to light is a strategy that could allow for the site-specific delivery of the reactive species NO to physiological targets. The photodissociation of NO from two nitrosylruthenium(II) isomer complexes {cis- and trans-[Ru(OAc)2NO]} was demonstrated by matrix-assisted laser desorption ionization time-of-flight mass spectrometry spectra, and electron paramagnetic resonance spectra further prove the photoinduced NO release by spin trapping of NO free radicals upon photoirradiation. Real-time NO release was quantitatively measured by electrochemistry with an NO-specific electrode. The quantitative control of NO release from [Ru(OAc)2NO] in aqueous solutions was done by photoirradiation at different wavelengths. Both isomers show photoinduced damage on plasmid DNA, but the trans isomer has higher cytotoxicity and photocytotoxicity activity against the HeLa tumor cell line than that of the cis isomer. Nitrosylruthenium(II) complex, with 8-quinolinol derivatives as ligands, has a great potential as a photoactivated NO donor reagent for biomedical applications.

  4. The potential for biologically catalyzed anaerobic methane oxidation on ancient Mars.

    PubMed

    Marlow, Jeffrey J; Larowe, Douglas E; Ehlmann, Bethany L; Amend, Jan P; Orphan, Victoria J

    2014-04-01

    This study examines the potential for the biologically mediated anaerobic oxidation of methane (AOM) coupled to sulfate reduction on ancient Mars. Seven distinct fluids representative of putative martian groundwater were used to calculate Gibbs energy values in the presence of dissolved methane under a range of atmospheric CO2 partial pressures. In all scenarios, AOM is exergonic, ranging from -31 to -135 kJ/mol CH4. A reaction transport model was constructed to examine how environmentally relevant parameters such as advection velocity, reactant concentrations, and biomass production rate affect the spatial and temporal dependences of AOM reaction rates. Two geologically supported models for ancient martian AOM are presented: a sulfate-rich groundwater with methane produced from serpentinization by-products, and acid-sulfate fluids with methane from basalt alteration. The simulations presented in this study indicate that AOM could have been a feasible metabolism on ancient Mars, and fossil or isotopic evidence of this metabolic pathway may persist beneath the surface and in surface exposures of eroded ancient terrains.

  5. Computational study on nitronium and nitrosonium oxalate: potential oxidizers for solid rocket propulsion?

    PubMed

    Gökçinar, Elif; Klapötke, Thomas M; Kramer, Michael P

    2010-08-26

    The enthalpies of formation for solid ionic nitrosonium oxalate, [NO](2)[O(2)C-CO(2)], nitronium oxalate, [NO(2)](2)[O(2)C-CO(2)], as well as covalent bis(nitroso)oxalic acid, ON-O(2)C-CO(2)-NO, and oxalic acid dinitrate ester, O(2)N-O(2)C-CO(2)-NO(2), were calculated using the complete basis set (CBS-4M) method of Petersson and coworkers to obtain very accurate energies. For the nitrosonium species, the ionic form ([NO](2)[O(2)C-CO(2)]) was identified as the more stable isomer, whereas for the nitrosonium compound, the covalently bound dinitrate ester (O(2)N-O(2)C-CO(2)-NO(2)) was found to be more stable. The combustion parameters with respect to possible use as ingredients in solid rocket motors for both stable species were calculated using the EXPLO5 and the ICT code. The performance of an aluminized formulation with covalently bound dinitrate ester (O(2)N-O(2)C-CO(2)-NO(2)) was shown to be comparable to that of ammonium perchlorate/aluminum. This makes oxalic acid dinitrate ester a potentially interesting perchlorate-free and environmentally benign oxidizer for solid rocket propulsion.

  6. Copper Oxide Nanomaterials Prepared by Solution Methods, Some Properties, and Potential Applications: A Brief Review

    PubMed Central

    Tran, Thi Ha; Nguyen, Viet Tuyen

    2014-01-01

    Cupric oxide (CuO), having a narrow bandgap of 1.2 eV and a variety of chemophysical properties, is recently attractive in many fields such as energy conversion, optoelectronic devices, and catalyst. Compared with bulk material, the advanced properties of CuO nanostructures have been demonstrated; however, the fact that these materials cannot yet be produced in large scale is an obstacle to realize the potential applications of this material. In this respect, chemical methods seem to be efficient synthesis processes which yield not only large quantities but also high quality and advanced material properties. In this paper, the effect of some general factors on the morphology and properties of CuO nanomaterials prepared by solution methods will be overviewed. In terms of advanced nanostructure synthesis, microwave method in which copper hydroxide nanostructures are produced in the precursor solution and sequentially transformed by microwave into CuO may be considered as a promising method to explore in the near future. This method produces not only large quantities of nanoproducts in a short reaction time of several minutes, but also high quality materials with advanced properties. A brief review on some unique properties and applications of CuO nanostructures will be also presented. PMID:27437488

  7. Polyol synthesis, functionalisation, and biocompatibility studies of superparamagnetic iron oxide nanoparticles as potential MRI contrast agents.