Science.gov

Sample records for multiple one-electron oxidations

  1. Consequence of one-electron oxidation and one-electron reduction for aniline.

    PubMed

    Raczyńska, Ewa D; Stępniewski, Tomasz M; Kolczyńska, Katarzyna

    2011-12-01

    Quantum-chemical calculations were performed for all possible isomers of neutral aniline and its redox forms, and intramolecular proton-transfer (prototropy) accompanied by π-electron delocalization was analyzed. One-electron oxidation (PhNH(2) - e → [PhNH(2)](+•)) has no important effect on tautomeric preferences. The enamine tautomer is preferred for oxidized aniline similarly as for the neutral molecule. Dramatical changes take place when proceeding from neutral to reduced aniline. One-electron reduction (PhNH(2) + e → [PhNH(2)](-•)) favors the imine tautomer. Independently on the state of oxidation, π- and n-electrons are more delocalized for the enamine than imine tautomers. The change of the tautomeric preferences for reduced aniline may partially explain the origin of the CH tautomers for reduced nucleobases (cytosine, adenine, and guanine).

  2. One-electron activation of water oxidation catalysis.

    PubMed

    Tamaki, Yusuke; Vannucci, Aaron K; Dares, Christopher J; Binstead, Robert A; Meyer, Thomas J

    2014-05-14

    Rapid water oxidation catalysis is observed following electrochemical oxidation of [Ru(II)(tpy)(bpz)(OH)](+) to [Ru(V)(tpy)(bpz)(O)](3+) in basic solutions with added buffers. Under these conditions, water oxidation is dominated by base-assisted Atom Proton Transfer (APT) and direct reaction with OH(-). More importantly, we report here that the Ru(IV)═O(2+) form of the catalyst, produced by 1e(-) oxidation of [Ru(II)(tpy)(bpz)(OH2)](2+) to Ru(III) followed by disproportionation to [Ru(IV)(tpy)(bpz)(O)](2+) and [Ru(II)(tpy)(bpz)(OH2)](2+), is also a competent water oxidation catalyst. The rate of water oxidation by [Ru(IV)(tpy)(bpz)(O)](2+) is greatly accelerated with added PO4(3-) with a turnover frequency of 5.4 s(-1) reached at pH 11.6 with 1 M PO4(3-) at an overpotential of only 180 mV.

  3. One electron oxidation of 3-methylcholanthrene: A chemical model for its mechanism of carcinogenesis

    NASA Astrophysics Data System (ADS)

    Lehner, Andreas F.; Horn, Jamie; Flesher, James W.

    2017-06-01

    One electron transfer oxidation has long been proposed as a route to the ultimate electrophilic and carcinogenic metabolites of both methylated and non-methylated polycyclic aromatic hydrocarbons (PAH). The carcinogenic hydrocarbon 3-methylcholanthrene (3-MC) has a methyl-analogous function at its meso-anthracenic center in the form of a dimethylene bridge, and treatment of this compound with the one electron transfer oxidizing reagent ferric ferricyanide, FeIII(FeIII(CN)6), in mixed aqueous-organic media generated multiple oxygenated species, many of which duplicate those found in mammalian metabolism including known carcinogens 1-hydroxy-3MC and 1-keto-3MC. These results are in agreement with a Unified Theory for PAH Carcinogenicity which predicts in vivo generation of a proximate benzylic alcohol metabolite from the 3-MC procarcinogen and conjugation with a moiety such as sulfate intended for rapid urinary excretion. The sulfate instead acts as a leaving group and generates an electrophilic carbocation capable of reacting with sensitive nucleophiles such as DNA in cellular nuclei. The products of one electron transfer oxidation align well with predictions of the Unified Theory since in many cases these products provide substrates or precursors for conjugation reactions.

  4. One-electron oxidations of ferrocenes: A pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Faraggi, Moshe; Weinraub, Dany; Broitman, Federico; DeFelippis, Michael R.; Klapper, Michael H.

    Using the pulse radiolysis technique we have studied the oxidation by various inorganic radicals of four water soluble ferrocene derivatives, hydroxyethyl, dimethylaminomethyl, monocarboxylic acid and dicarboxylic acid. We report the second order rate constants for these reactions, the stabilities and spectral properties of the ferrocinium products, and the electrochemically determined ferrocinium/ferrocene redox potentials. We also present preliminary estimates of tyrosine and tryptophan radical redox potentials obtained with the dicarboxylic acid ferrocene derivative as reference, and we discuss the relationship between redox potential differences and the reactivities of the ferrocenes with the inorganic radicals.

  5. 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...

  6. 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...

  7. Methionine one-electron oxidation: Coherent contributions from radiolysis, IRMPD spectroscopy, DFT calculations and electrochemistry

    NASA Astrophysics Data System (ADS)

    Scuderi, Debora; Bergès, Jacqueline; de Oliveira, Pedro; Houée-Levin, Chantal

    2016-11-01

    Methionine is an essential amino acid, unfortunately prone to oxidation. The mechanism of its oxidation by •OH radicals has been studied for more than 40 years and still remains misunderstood. We have reinvestigated the oxidation of this residue in model peptides, aiming at i) improving the identification of free radicals by the use of more modern quantum chemistry methods; ii) reinvestigating the one-electron reduction potentials as a function of the position in the sequence; iii) identifying the final compounds, which were still unknown; iv) reinvestigating the intramolecular electron transfer (IET) involving this residue.

  8. Oxidatively generated base damage to cellular DNA by hydroxyl radical and one-electron oxidants: similarities and differences.

    PubMed

    Cadet, Jean; Wagner, J Richard

    2014-09-01

    Hydroxyl radical (OH) and one-electron oxidants that may be endogenously formed through oxidative metabolism, phagocytosis, inflammation and pathological conditions constitute the main sources of oxidatively generated damage to cellular DNA. It is worth mentioning that exposure of cells to exogenous physical agents (UV light, high intensity UV laser, ionizing radiation) and chemicals may also induce oxidatively generated damage to DNA. Emphasis is placed in this short review article on the mechanistic aspects of OH and one-electron oxidant-mediated formation of single and more complex damage (tandem lesions, intra- and interstrand cross-links, DNA-protein cross-links) in cellular DNA arising from one radical hit. This concerns DNA modifications that have been accurately measured using suitable analytical methods such as high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry. Evidence is provided that OH and one-electron oxidants after generating neutral radicals and base radical cations respectively may partly induce common degradation pathways. In addition, selective oxidative reactions giving rise to specific degradation products of OH and one-electron oxidation reactions that can be used as representative biomarkers of these oxidants have been identified.

  9. One-electron oxidation reactions of purine and pyrimidine bases in cellular DNA

    PubMed Central

    Cadet, Jean; Wagner, J. Richard; Shafirovich, Vladimir; Geacintov, Nicholas E.

    2014-01-01

    Purpose The aim of this survey is to critically review the available information on one-electron oxidation reactions of nucleobases in cellular DNA with emphasis on damage induced through the transient generation of purine and pyrimidine radical cations. Since the indirect effect of ionizing radiation mediated by hydroxyl radical is predominant in cells, efforts have been made to selectively ionize bases using suitable one-electron oxidants that consist among others of high intensity UVC laser pulses. Thus, the main oxidation product in cellular DNA was found to be 8-oxo-7,8-dihydroguanine as a result of direct bi-photonic ionization of guanine bases and indirect formation of guanine radical cations through hole transfer reactions from other base radical cations. The formation of 8-oxo-7,8-dihydroguanine and other purine and pyrimidine degradation products was rationalized in terms of the initial generation of related radical cations followed by either hydration or deprotonation reactions in agreement with mechanistic pathways inferred from detailed mechanistic studies. The guanine radical cation has been shown to be implicated in three other nucleophilic additions that give rise to DNA-protein and DNA-DNA cross-links in model systems. Evidence was recently provided for the occurrence of these three reactions in cellular DNA. Conclusion There is growing evidence that one-electron oxidation reactions of nucleobases whose mechanisms have been characterized in model studies involving aqueous solutions take place in a similar way in cells. It may also be pointed out that the above cross-linked lesions are only produced from the guanine radical cation and may be considered as diagnostic products of the direct effect of ionizing radiation. PMID:24369822

  10. On the kinetics and energetics of one-electron oxidation of 1,3,5-triazines.

    PubMed

    Azenha, M E D G; Burrows, H D; Canle, M; Coimbra, R; Fernández, M I; García, M V; Rodrigues, A E; Santaballa, J A; Steenken, S

    2003-01-07

    One-electron oxidation of 1,3,5-triazines is observed with both excited uranyl ion (*UO2(2+)) and sulfate radical anion (SO4.-) in aqueous solution, but not with Tl2+, indicating that the standard reduction potentials E degree of 1,3,5-triazine radical cations are = 2.3 +/- 0.1 V vs. NHE, consistent with theoretical calculations; this suggests that if triazines inhibit electron transfer during photosynthesis, they would need to act on the reductive part of the electron transport chain.

  11. Pulse radiolysis of silybin: One-electron oxidation of the flavonoid at neutral pH

    NASA Astrophysics Data System (ADS)

    György, I.; Antus, S.; Földiák, G.

    One-electron oxidation of silybin, a flavonoid drug used in human therapy of liver, was investigated by pulse radiolysis at neutral pH. Phenoxyl radicals formed from the substrate by oxidising N .3 radicals were identified by comparing the transient optical absorption spectra with those obtained from model compounds. The orto-methoxy-phenolic structure (ring B) is the exclusive target for one-electron oxidation of silybin. The 5.7-dihydroxy-chromanone moiety (ring A) withstands free-radical attack at neutral pH due to the chelatic H-bond (p Ka = 10.2) existing between the 5-OH and 4-oxo groups. Hydroxyl radicals react with silybin at diffusion controlled rate ( k = 1.8 x 10 10 dm 3 mol -1 s -1). The reactivity of silybin towards free radicals at neutral pH is conform with the assumption that the physiological activity of the flavonoid is due to its chain-breaking antioxidant behaviour.

  12. Monitoring one-electron photo-oxidation of guanine in DNA crystals using ultrafast infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Hall, James P.; Poynton, Fergus E.; Keane, Páraic M.; Gurung, Sarah P.; Brazier, John A.; Cardin, David J.; Winter, Graeme; Gunnlaugsson, Thorfinnur; Sazanovich, Igor V.; Towrie, Michael; Cardin, Christine J.; Kelly, John M.; Quinn, Susan J.

    2015-12-01

    To understand the molecular origins of diseases caused by ultraviolet and visible light, and also to develop photodynamic therapy, it is important to resolve the mechanism of photoinduced DNA damage. Damage to DNA bound to a photosensitizer molecule frequently proceeds by one-electron photo-oxidation of guanine, but the precise dynamics of this process are sensitive to the location and the orientation of the photosensitizer, which are very difficult to define in solution. To overcome this, ultrafast time-resolved infrared (TRIR) spectroscopy was performed on photoexcited ruthenium polypyridyl-DNA crystals, the atomic structure of which was determined by X-ray crystallography. By combining the X-ray and TRIR data we are able to define both the geometry of the reaction site and the rates of individual steps in a reversible photoinduced electron-transfer process. This allows us to propose an individual guanine as the reaction site and, intriguingly, reveals that the dynamics in the crystal state are quite similar to those observed in the solvent medium.

  13. One-electron oxidation of ruthenocene: reactions of the ruthenocenium ion in gentle electrolyte media.

    PubMed

    Swarts, Jannie C; Nafady, Ayman; Roudebush, John H; Trupia, Sabrina; Geiger, William E

    2009-03-02

    The electrochemical oxidation of ruthenocene, RuCp(2) (Cp = eta(5)-C(5)H(5)), 1, has been studied in dichloromethane using a supporting electrolyte containing either the [B(C(6)F(5))(4)](-) (TFAB) or the [B(C(6)H(3)(CF(3))(2))(4)](-) (BArF(24)) counteranion. A quasi-Nernstian process was observed in both cases, with E(1/2) values of 0.41 and 0.57 V vs FeCp(2) in the respective electrolyte media. The ruthenocenium ion 1(+) equilibrates with a metal-metal bonded dimer [Ru(2)Cp(4)](2+), 2(2+), that is increasingly preferred at low temperatures. Dimerization equilibrium constants determined by digital simulation of cyclic voltammetry (CV) curves were in the range of 10(2)-10(4) M(-1) at temperatures of 256 to 298 K. Near room temperature, and particularly when BArF(24) is the counteranion, the dinuclear species [Ru(2)Cp(2)(sigma:eta(5)-C(5)H(4))(2)] (2+), 3(2+), in which each metal is sigma-bonded to a cyclopentadienyl ring, was the preferred electrolytic oxidation product. Cathodic reduction of 3(2+) regenerated ruthenocene. The two dinuclear products, 2(2+) and 3(2+), were characterized by (1)H NMR spectroscopy on anodically electrolyzed solutions of 1 at low temperatures in CD(2)Cl(2)/[NBu(4)][BArF(24)]. The variable temperature NMR behavior of these solutions showed that 3(2+) and 2(2+) take part in a thermal equilibrium, the latter being dominant at the lowest temperatures. Ruthenocene hydride, [1-H](+), was also identified as being present in the electrolysis solutions. The oxidation of ruthenocene is shown to be an inherent one-electron process, giving a ruthenocenium ion which is highly susceptible to reactions that allow it to regain an 18-electron configuration. In a dry non-donor solvent, and in the absence of nucleophiles, this electronic configuration is attained by self-reactions involving formation of Ru-Ru or Ru-C bonds. The present data offer a mechanistic explanation for the previously described results on the chemical oxidation of osmocene (Droege, M

  14. One-Electron Reduction of Penicillins in Relation to the Oxidative Stress Phenomenon

    PubMed Central

    Szabó, László; Tóth, Tünde; Takács, Erzsébet; Wojnárovits, László

    2015-01-01

    Certain bactericidal antibiotics target mitochondrial components and, due to the leakage of electrons from the electron transport chain, one-electron reduction might occur that can lead to intermediates passing the electron to suitable acceptors. This study aimed at investigating the one-electron reduction mechanism of selected penicillin derivatives using pulse radiolysis techniques. Penicillins can accommodate the electron on each of their carbonyl carbon. Ketyl radicals are thus produced, which are reducing agents with possibility to interact with suitable biomolecules. A detailed mechanism of the reduction is reported. PMID:26690427

  15. Enzymatic recycling of oxidized ascorbate in pig heart: one-electron vs two-electron pathway.

    PubMed

    Coassin, M; Tomasi, A; Vannini, V; Ursini, F

    1991-11-01

    Enzymatic systems able to reduce either dehydroascorbate or ascorbyl radical back to ascorbate by "recycling" vitamin C may contribute to lowering the nutritional requirement of it and to increase tissue antioxidant capacity. The activities of two enzymatic activities, GSH-dehydroascorbate reductase (two-electron reduction pathway) and NADH-semidehydroascorbate reductase (one-electron reduction pathway) in pig tissues, have been investigated. The activity of glutathione-dependent reduction of dehydroascorbate, although measurable, appeared negligible taking into consideration the low physiological substrate concentration. On the other hand, the one-electron reduction of ascorbyl radical resulted fast enough to slow down the consumption of the antioxidant vitamin.

  16. One-Electron Reduction of Penicillins in Relation to the Oxidative Stress Phenomenon.

    PubMed

    Szabó, László; Tóth, Tünde; Takács, Erzsébet; Wojnárovits, László

    2015-12-11

    Certain bactericidal antibiotics target mitochondrial components and, due to the leakage of electrons from the electron transport chain, one-electron reduction might occur that can lead to intermediates passing the electron to suitable acceptors. This study aimed at investigating the one-electron reduction mechanism of selected penicillin derivatives using pulse radiolysis techniques. Penicillins can accommodate the electron on each of their carbonyl carbon. Ketyl radicals are thus produced, which are reducing agents with possibility to interact with suitable biomolecules. A detailed mechanism of the reduction is reported.

  17. π to σ Radical Tautomerization in One-Electron Oxidized 1-Methylcytosine and its Analogs

    PubMed Central

    Adhikary, Amitava; Kumar, Anil; Bishop, Casandra T.; Wiegand, Tyler J.; Hindi, Ragda M.; Adhikary, Ananya; Sevilla, Michael D.

    2015-01-01

    In this work iminyl σ-radical formation in several one-electron oxidized cytosine analogs including 1-MeC, cidofovir, 2′-deoxycytidine (dCyd), and 2′-deoxycytidine 5′-monophosphate (5′-dCMP) were investigated in homogeneous aqueous (D2O or H2O) glassy solutions at low temperatures employing electron spin resonance (ESR) spectroscopy. Employing density functional theory (DFT) (DFT/B3LYP/6-31G* method), the calculated hyperfine coupling constant (HFCC) values of iminyl σ-radical agree quite well with the experimentally observed ones thus confirming its assignment. ESR and DFT studies show that the cytosine-iminyl σ-radical is a tautomer of the deprotonated cytosine π-cation radical (cytosine π-aminyl radical, C(N4-H)•). Employing 1-MeC samples at various pHs ranging ca. 8 to ca. 11, ESR studies show that the tautomeric equilibrium between C(N4-H)• and the iminyl σ-radical at low temperature is too slow to be established without added base. ESR and DFT studies agree that in the iminyl-σ radical, the unpaired spin is localized to the exocyclic nitrogen (N4) in an in-plane pure p-orbital. This gives rise to an anisotropic nitrogen hyperfine coupling (Azz = 40 G) from N4 and a near isotropic β-nitrogen coupling of 9.7 G from the cytosine ring nitrogen at N3. Iminyl σ-radical should exist in its N3-protonated form as the N3-protonated iminyl σ-radical is stabilized in solution by over 30 kcal/mol (ΔG= −32 kcal/mol) over its conjugate base, the N3-deprotonated form. This is the first observation of an isotropic β-hyperfine ring nitrogen coupling in an N-centered DNA-radical. Our theoretical calculations predict that the cytosine iminyl σ-radical can be formed in dsDNA by a radiation-induced ionization–deprotonation process that is only 10 kcal/mol above the lowest energy path. PMID:26237072

  18. One electron-controlled multiple-valued dynamic random-access-memory

    NASA Astrophysics Data System (ADS)

    Kye, H. W.; Song, B. N.; Lee, S. E.; Kim, J. S.; Shin, S. J.; Choi, J. B.; Yu, Y.-S.; Takahashi, Y.

    2016-02-01

    We propose a new architecture for a dynamic random-access-memory (DRAM) capable of storing multiple values by using a single-electron transistor (SET). The gate of a SET is designed to be connected to a plurality of DRAM unit cells that are arrayed at intersections of word lines and bitlines. In this SET-DRAM hybrid scheme, the multiple switching characteristics of SET enables multiple value data stored in a DRAM unit cell, and this increases the storage functionality of the device. Moreover, since refreshing data requires only a small amount of SET driving current, this enables device operating with low standby power consumption.

  19. One-electron properties using a CI method based on multiple Hartree-Fock solutions

    NASA Astrophysics Data System (ADS)

    Malbouisson, L. A. C.; Martins, M. G. R.; Makiuchi, N.

    A multi-reference configuration interaction (CI) method based on multiple Hartree-Fock (HF) solutions is applied to study the permanent dipole moment of the LiH, BH, FH, and H2O systems with the minimal atomic basis. The LiH was also calculated with the double-zeta atomic basis. This method uses several HF solutions as references to expand the state functions. For each one of the systems studied, several HF solutions were obtained in the appropriate point and spin symmetry classes, i.e., 1?+ and 1A1. With each of these solutions is generated a distinct basis of the same full CI space. The set of these bases is a system of generators of the full CI space and the multi-reference HF (MRHF) bases are built mixing configuration state functions (CSFs) originated from distinct HF solutions.

  20. One-electron oxidation of ergothioneine and analogues investigated by pulse radiolysis: redox reaction involving ergothioneine and vitamin C.

    PubMed Central

    Asmus, K D; Bensasson, R V; Bernier, J L; Houssin, R; Land, E J

    1996-01-01

    Redox reactions of endogenous and exogenous sulphur-containing compounds are involved in protection against oxidative damage arising from the incidence and/or treatment of many diseases, including cancer. We have investigated, via pulse radiolysis, the one-electron oxidation of ergothioneine, a molecule with antioxidant properties which is detected at millimolar concentrations in certain tissues and fluids subject to oxidative stress, including erythrocytes and plasma. The spectrum of the transient species, assigned to the product of one-electron oxidation, observed after reaction of ergothioneine with the oxidizing radicals OH., N3. and CCl3O2. has a maximum absorption at 520 nm and is very similar to that obtained by oxidation of analogous molecules such as 2-mercaptoimidazole, 1-methyl-2-mercaptoimidazole, S-methyl- and S,N-dimethyl-ergothioneine. In the presence of vitamin C, the oxidized form of ergothioneine is repaired by a rapid reduction (k = 6.3 x 10(8) M(-1).s(-1)) producing ascorbyl radicals. This co-operative interaction between ergothionine and ascorbate, similar to that previously observed between vitamin E and ascorbate, may contribute to essential biological redox protection. PMID:8615839

  1. One-electron oxidation in irradiated carbon tetrachloride solutions of ZnTPP, TMPD, and phenols. [Pulsed irradiation

    SciTech Connect

    Grodkowski, J.; Neta, P.

    1984-03-15

    One-electron oxidation of phenol, p-methoxphenol, N,N,N',N'-tetramethyl-p-phenylenediamine, chlorpromazine, and zinc tetraphenolporphyrin (ZnTPP) was studied by pulse radiolysis in carbon tetrachloride solutions. Phenols form phenoxyl radicals and the other compounds form cation radicals with yields strongly dependent on solute concentration. The highest yield in deoxygenated solutions approached G = 4. In the presence of oxygen an additional oxidation step is observed owing to CCl/sub 3/O/sub 2/ radicals and the overall oxidation yield approached G = 8. ZnTPP was found to be oxidized to the cation radical without any side effects, unlike oxidation in 1,2-dichloroethane which was accompanied by demetallation owing to HCl production.

  2. One-electron oxidation of gemcitabine and analogs: mechanism of formation of C3' and C2' sugar radicals.

    PubMed

    Adhikary, Amitava; Kumar, Anil; Rayala, Ramanjaneyulu; Hindi, Ragda M; Adhikary, Ananya; Wnuk, Stanislaw F; Sevilla, Michael D

    2014-11-05

    Gemcitabine is a modified cytidine analog having two fluorine atoms at the 2'-position of the ribose ring. It has been proposed that gemcitabine inhibits RNR activity by producing a C3'• intermediate via direct H3'-atom abstraction followed by loss of HF to yield a C2'• with 3'-keto moiety. Direct detection of C3'• and C2'• during RNR inactivation by gemcitabine still remains elusive. To test the influence of 2'- substitution on radical site formation, electron spin resonance (ESR) studies are carried out on one-electron oxidized gemcitabine and other 2'-modified analogs, i.e., 2'-deoxy-2'-fluoro-2'-C-methylcytidine (MeFdC) and 2'-fluoro-2'-deoxycytidine (2'-FdC). ESR line components from two anisotropic β-2'-F-atom hyperfine couplings identify the C3'• formation in one-electron oxidized gemcitabine, but no further reaction to C2'• is found. One-electron oxidized 2'-FdC is unreactive toward C3'• or C2'• formation. In one-electron oxidized MeFdC, ESR studies show C2'• production presumably from a very unstable C3'• precursor. The experimentally observed hyperfine couplings for C2'• and C3'• match well with the theoretically predicted ones. C3'• to C2'• conversion in one-electron oxidized gemcitabine and MeFdC has theoretically been modeled by first considering the C3'• and H3O(+) formation via H3'-proton deprotonation and the subsequent C2'• formation via HF loss induced by this proximate H3O(+). Theoretical calculations show that in gemcitabine, C3'• to C2'• conversion in the presence of a proximate H3O(+) has a barrier in agreement with the experimentally observed lack of C3'• to C2'• conversion. In contrast, in MeFdC, the loss of HF from C3'• in the presence of a proximate H3O(+) is barrierless resulting in C2'• formation which agrees with the experimentally observed rapid C2'• formation.

  3. Prototropic Equilibria in DNA Containing One-electron Oxidized GC: Intra-duplex vs. Duplex to Solvent Deprotonation

    PubMed Central

    Adhikary, Amitava; Kumar, Anil; Munafo, Shawn A.; Khanduri, Deepti; Sevilla, Michael D.

    2015-01-01

    By use of ESR and UV-vis spectral studies, this work identifies the protonation states of one-electron oxidized G:C (viz. G•+:C, G(N1-H)•:C(+H+), G(N1-H)•:C, and G(N2-H)•:C) in a DNA oligomer d[TGCGCGCA]2. Benchmark ESR and UV-vis spectra from one electron oxidized 1-Me-dGuo are employed to analyze the spectral data obtained in one-electron oxidized d[TGCGCGCA]2 at various pHs. At pH ≥7, the initial site of deprotonation of one-electron oxidized d[TGCGCGCA]2 to the surrounding solvent is found to be at N1 forming G(N1-H)•:C at 155 K. However, upon annealing to 175 K, the site of deprotonation to the solvent shifts to an equilibrium mixture of G(N1-H)•:C and G(N2-H)•:C. For the first time, the presence of G(N2-H)•:C in a ds DNA-oligomer is shown to be easily distinguished from the other prototropic forms, owing to its readily observable nitrogen hyperfine coupling (Azz(N2)= 16 G). In addition, for the oligomer in H2O, an additional 8 G N2-H proton HFCC is found. This ESR identification is supported by a UV-vis absorption at 630 nm which is characteristic for G(N2-H)• in model compounds and oligomers. We find that the extent of photo-conversion to the C1′ sugar radical (C1′•) in the one-electron oxidized d[TGCGCGCA]2 allows for a clear distinction among the various G:C protonation states which can not be easily distinguished by ESR or UV-vis spectroscopies with this order for the extent of photo-conversion: G•+:C > G(N1-H)•:C(+H+) >> G(N1-H)•:C. We propose that it is the G•+:C form that undergoes deprotonation at the sugar and this requires reprotonation of G within the lifetime of exited state. PMID:21491657

  4. Defining the Electronic and Geometric Structure of One-Electron Oxidized Copper–Bis-phenoxide Complexes

    PubMed Central

    Storr, Tim; Verma, Pratik; Pratt, Russell C.; Wasinger, Erik C.; Shimazaki, Yuichi; Stack, T. Daniel P.

    2009-01-01

    The geometric and electronic structure of an oxidized Cu complex ([CuSal]+; Sal = N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with a non-innocent salen ligand has been investigated both in the solid state and in solution. Integration of information from UV–vis–NIR spectroscopy, magnetic susceptibility, electrochemistry, resonance Raman spectroscopy, X-ray crystallography, X-ray absorption spectroscopy, and density functional theory calculations provides critical insights into the nature of the localization/delocalization of the oxidation locus. In contrast to the analogous Ni derivative [NiSal]+ (Storr, T.; et al. Angew. Chem., Int. Ed. 2007, 46, 5198), which exists solely in the Ni(II) ligand-radical form, the locus of oxidation is metal-based for [CuSal]+, affording exclusively a Cu(III) species in the solid state (4–300 K). Variable-temperature solution studies suggest that [CuSal]+ exists in a reversible spin-equilibrium between a ligand-radical species [Cu(II)Sal•]+ (S = 1) and the high-valent metal form [Cu(III)Sal]+ (S = 0), indicative of nearly isoenergetic species. It is surprising that a bis-imine–bis-phenolate ligation stabilizes the Cu(III) oxidation state, and even more surprising that in solution a spin equilibrium occurs without a change in coordination number. The oxidized tetrahydrosalen analogue [CuSalred]+ (Salred = N, N′-bis(3,5-di-tert-butylhydroxybenzyl)-1,2-cyclohexane-(1R,2R)-diamine) exists as a temperature-invariant Cu(II)–ligand-radical complex in solution, demonstrating that ostensibly simple variations of the ligand structure affect the locus of oxidation in Cu–bis-phenoxide complexes. PMID:18939830

  5. Defining the electronic and geometric structure of one-electron oxidized copper-bis-phenoxide complexes.

    PubMed

    Storr, Tim; Verma, Pratik; Pratt, Russell C; Wasinger, Erik C; Shimazaki, Yuichi; Stack, T Daniel P

    2008-11-19

    The geometric and electronic structure of an oxidized Cu complex ([CuSal](+); Sal = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with a non-innocent salen ligand has been investigated both in the solid state and in solution. Integration of information from UV-vis-NIR spectroscopy, magnetic susceptibility, electrochemistry, resonance Raman spectroscopy, X-ray crystallography, X-ray absorption spectroscopy, and density functional theory calculations provides critical insights into the nature of the localization/delocalization of the oxidation locus. In contrast to the analogous Ni derivative [NiSal](+) (Storr, T.; et al. Angew. Chem., Int. Ed. 2007, 46, 5198), which exists solely in the Ni(II) ligand-radical form, the locus of oxidation is metal-based for [CuSal](+), affording exclusively a Cu(III) species in the solid state (4-300 K). Variable-temperature solution studies suggest that [CuSal](+) exists in a reversible spin-equilibrium between a ligand-radical species [Cu(II)Sal(*)](+) (S = 1) and the high-valent metal form [Cu(III)Sal](+) (S = 0), indicative of nearly isoenergetic species. It is surprising that a bis-imine-bis-phenolate ligation stabilizes the Cu(III) oxidation state, and even more surprising that in solution a spin equilibrium occurs without a change in coordination number. The oxidized tetrahydrosalen analogue [CuSal(red)](+) (Sal(red) = N,N'-bis(3,5-di- tert-butylhydroxybenzyl)-1,2-cyclohexane-(1R,2R)-diamine) exists as a temperature-invariant Cu(II)-ligand-radical complex in solution, demonstrating that ostensibly simple variations of the ligand structure affect the locus of oxidation in Cu-bis-phenoxide complexes.

  6. Defining the Electronic And Geometric Structure of One-Electron Oxidized Copper-Bis-Phenoxide Complexes

    SciTech Connect

    Storr, T.; Verma, P.; Pratt, R.C.; Wasinger, E.C.; Shimazaki, Y.; Stack, T.D.P.

    2009-05-26

    The geometric and electronic structure of an oxidized Cu complex ([CuSal](+); Sal = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with a non-innocent salen ligand has been investigated both in the solid state and in solution. Integration of information from UV-vis-NIR spectroscopy, magnetic susceptibility, electrochemistry, resonance Raman spectroscopy, X-ray crystallography, X-ray absorption spectroscopy, and density functional theory calculations provides critical insights into the nature of the localization/delocalization of the oxidation locus. In contrast to the analogous Ni derivative [NiSal](+) (Storr, T.; et al. Angew. Chem., Int. Ed. 2007, 46, 5198), which exists solely in the Ni(II) ligand-radical form, the locus of oxidation is metal-based for [CuSal](+), affording exclusively a Cu(III) species in the solid state (4-300 K). Variable-temperature solution studies suggest that [CuSal](+) exists in a reversible spin-equilibrium between a ligand-radical species [Cu(II)Sal(*)](+) (S = 1) and the high-valent metal form [Cu(III)Sal](+) (S = 0), indicative of nearly isoenergetic species. It is surprising that a bis-imine-bis-phenolate ligation stabilizes the Cu(III) oxidation state, and even more surprising that in solution a spin equilibrium occurs without a change in coordination number. The oxidized tetrahydrosalen analogue [CuSal(red)](+) (Sal(red) = N,N'-bis(3,5-di- tert-butylhydroxybenzyl)-1,2-cyclohexane-(1R,2R)-diamine) exists as a temperature-invariant Cu(II)-ligand-radical complex in solution, demonstrating that ostensibly simple variations of the ligand structure affect the locus of oxidation in Cu-bis-phenoxide complexes.

  7. π- vs σ-radical states of one-electron-oxidized DNA/RNA bases: a density functional theory study.

    PubMed

    Kumar, Anil; Sevilla, Michael D

    2013-10-03

    As a result of their inherent planarity, DNA base radicals generated by one-electron oxidation/reduction or bond cleavage form π- or σ-radicals. While most DNA base systems form π-radicals, there are a number of nucleobase analogues such as one-electron-oxidized 6-azauraci1, 6-azacytosine, and 2-thiothymine or one-electron reduced 5-bromouracil that form more reactive σ-radicals. Elucidating the availability of these states within DNA, base radical electronic structure is important to the understanding of the reactivity of DNA base radicals in different environments. In this work, we address this question by the calculation of the relative energies of π- and σ-radical states in DNA/RNA bases and their analogues. We used density functional theory B3LYP/6-31++G** method to optimize the geometries of π- and σ-radicals in Cs symmetry (i.e., planar) in the gas phase and in solution using the polarized continuum model (PCM). The calculations predict that σ- and π-radical states in one-electron-oxidized bases of thymine, T(N3-H)(•), and uracil, U(N3-H)(•), are very close in energy; i.e., the π-radical is only ca. 4 kcal/mol more stable than the σ-radical. For the one-electron-oxidized radicals of cytosine, C(•+), C(N4-H)(•), adenine, A(•+), A(N6-H)(•), and guanine, G(•+), G(N2-H)(•), G(N1-H)(•), the π-radicals are ca. 16-41 kcal/mol more stable than their corresponding σ-radicals. Inclusion of solvent (PCM) is found to stabilize the π- over σ-radical of each of the systems. U(N3-H)(•) with three discrete water molecules in the gas phase is found to form a three-electron σ bond between the N3 atom of uracil and the O atom of a water molecule, but on inclusion of full solvation and discrete hydration, the π-radical remains most stable.

  8. 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.

  9. One-electron Initiated Two-electron Oxidation of Water by Aluminum Porphyrins with Earth's Most Abundant Metal Ion.

    PubMed

    Kuttassery, Fazalurahman; Mathew, Siby; Sagawa, Shogo; Remello, Sebastian Nybin; Thomas, Arun; Yamamoto, Daisuke; Onuki, Satomi; Nabetani, Yu; Tachibana, Hiroshi; Inoue, Haruo

    2017-03-20

    We report here a new molecular catalyst for efficient water splitting, aluminum porphyrins (tetra-methylpyridiniumylporphyrinatealuminum: AlTMPyP), containing the Earth's most abundant metal as the central ion. One-electron oxidation of the aluminum porphyrin initiates the two-electron oxidation of water to form hydrogen peroxide as the primary reaction product with the lowest known overpotential (97 mV). The aluminum-peroxo complex was clearly detected by a cold-spray ionization mass-spectrometry in HRMS mode and the structure of the intermediate was further confirmed using laser-Raman spectroscopy, indicating the hydroperoxy complex of AlTMPyP to be the key intermediate in the reaction. The two-electron oxidation of water to form hydrogen peroxide was essentially quantitative, with a Faradaic efficiency of 99%. The catalytic reaction was found to be highly efficient, with a turnover frequency up to ~ 2 × 10⁴ s¯¹. A reaction mechanism is proposed involving oxygen-oxygen bond formation by the attack of a hydroxide ion on the oxyl-radical-like axial ligand oxygen atom in the one-electron-oxidized form of AlTMPyP(O¯)₂, followed by a second electron transfer to the electrode.

  10. The one-electron oxidation of a dithiolate molecule: The importance of chemical intuition

    SciTech Connect

    Bushnell, Eric A. C.; Burns, Thomas D.; Boyd, Russell J.

    2014-05-14

    A series of nine commonly used density functional methods were assessed to accurately predict the oxidation potential of the (C{sub 2}H{sub 2}S{sub 2}{sup −2}/C{sub 2}H{sub 2}S{sub 2}{sup •−}) redox couple. It was found that due to their greater tendency for charge delocalization the GGA functionals predict a structure where the radical electron is delocalized within the alkene backbone of C{sub 2}H{sub 2}S{sub 2}{sup •−}, whereas the hybrid functionals and the reference QCISD/cc-pVTZ predict that the radical electron remains localized on the sulfurs. However, chemical intuition suggests that the results obtained with the GGA functionals should be correct. Indeed, with the use of the geometries obtained at the HCTH/6-311++G(3df,3pd) level of theory both the QCISD and hybrid DFT methods yield a molecule with a delocalized electron. Notably, this new molecule lies at least 53 kJ mol{sup −1} lower in energy than the previously optimized one that had a localized radical. Using these new structures the calculated oxidation potential was found to be 2.71–2.97 V for the nine DFT functionals tested. The M06-L functional provided the best agreement with the QCISD/cc-pVTZ reference oxidation potential of 3.28 V.

  11. 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

  12. Two-electron reduction and one-electron oxidation of organic hydroperoxides by human myeloperoxidase.

    PubMed

    Furtmüller, P G; Burner, U; Jantschko, W; Regelsberger, G; Obinger, C

    2000-11-03

    The reaction of native myeloperoxidase (MPO) and its redox intermediate compound I with hydrogen peroxide, ethyl hydroperoxide, peroxyacetic acid, t-butyl hydroperoxide, 3-chloroperoxybenzoic acid and cumene hydroperoxide was studied by multi-mixing stopped-flow techniques. Hydroperoxides are decomposed by MPO by two mechanisms. Firstly, the hydroperoxide undergoes a two-electron reduction to its corresponding alcohol and heme iron is oxidized to compound I. At pH 7 and 15 degrees C, the rate constant of the reaction between 3-chloroperoxybenzoic acid and ferric MPO was similar to that with hydrogen peroxide (1.8x10(7) M(-1) s(-1) and 1.4x10(7) M(-1) s(-1), respectively). With the exception of t-butyl hydroperoxide, the rates of compound I formation varied between 5.2x10(5) M(-1) s(-1) and 2.7x10(6) M(-1) s(-1). Secondly, compound I can abstract hydrogen from these peroxides, producing peroxyl radicals and compound II. Compound I reduction is shown to be more than two orders of magnitude slower than compound I formation. Again, with 3-chloroperoxybenzoic acid this reaction is most effective (6. 6x10(4) M(-1) s(-1) at pH 7 and 15 degrees C). Both reactions are controlled by the same ionizable group (average pK(a) of about 4.0) which has to be in its conjugated base form for reaction.

  13. One-electron oxidation of mitomycin C and its corresponding peroxyl radicals. A steady-state and pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Getoff, Nikola; Solar, Sonja; Quint, Ruth M.

    1997-12-01

    The one-electron oxidation of Mitomycin C (MMC) as well as the formation of the corresponding peroxyl radicals were investigated by both steady-state and pulse radiolysis. The steady-state MMC-radiolysis by OH-attack followed at both absorption bands showed different yields: at 218 nm G i (-MMC) = 3.0 and at 364 nm G i (-MMC) = 3.9, indicating the formation of various not yet identified products, among which ammonia was determined, G(NH 3) = 0.81. By means of pulse radiolysis it was established a total κ (OH + MMC) = (5.8 ± 0.2) × 10 9 dm 3 mol -1 s -1. The transient absorption spectrum from the one-electron oxidized MMC showed absorption maxima at 295 nm ( ɛ = 9950 dm 3 mol -1 cm t-1 ), 410 nm ( ɛ = 1450 dm 3 mol -1 cm -1) and 505 nm ( ɛ = 5420 dm 3 mol -1 cm -1). At 280-320 and 505 nm and above they exhibit in the first 150 μs a first order decay, κ1 = (0.85 ± 0.1) × 10 3 s -1, and followed upto ms time range, by a second order decay, 2 κ = (1.3 ± 0.3) × 10 8 dm 3 mol -1 s -1. Around 410 nm the kinetics are rather mixed and could not be resolved. The steady-state MMC-radiolysis in the presence of oxygen featured a proportionality towards the absorbed dose for both MMC-absorption bands, resulting in a G i (-MMC) = 1.5. Among several products ammonia-yield was determined G(NH 3) = 0.52. The formation of MMC-peroxyl radicals was studied by pulse radiolysis, likewise in neutral aqueous solution, but saturated with a gas mixture of 80% N 2O and 20% O 2. The maxima of the observed transient spectrum are slightly shifted compared to that of the one-electron oxidized MMC-species, namely: 290 nm ( ɛ = 10100 dm 3 mol -1 cm -1), 410 nm ( ɛ = 2900 dm 3 mol -1 cm -1) and 520 nm ( ɛ = 5500 dm 3 mol -1 cm -1). The O 2-addition to the MMC-one-electron oxidized transients was found to be at 290 to 410 nm gk(MMC·OH + O 2) = 5 × 10 7 dm 3 mol -1 s -1, around 480 nm κ = 1.6 × 10 8 dm 3 mol -1 s -1 and at 510 nm and above, κ = 3 × 10 8 dm 3 mol -1 s -1. The

  14. Electrochemical one-electron oxidation of low-generation polyamidoamine-type dendrimers with a 1,4-phenylenediamine core.

    PubMed

    Hammerich, Ole; Hansen, Thomas; Thorvildsen, Asbjørn; Christensen, Jørn B

    2009-08-03

    A series of polyamidoamine (PAMAM)-type dendrimers with a 1,4-phenylenediamine (PD) core is prepared from PD by procedures including Michael addition of methyl acrylate followed by aminolysis with 1,2-ethanediamine. Their one-electron oxidation potentials are determined by differential pulse voltammetry (DPV) in methanol, acetonitrile, dichloromethane, and dimethyl sulfoxide. The dendrimers are more difficult to oxidize than N,N,N',N'-tetramethyl-p-phenylenediamine (TMePD). The oxidation potentials decrease with increasing dendrimer generation up to G0.5, after which the potential is essentially constant up to G2.0. The structures of both the neutral species and the radical cations are studied by DFT calculations at the B3LYP/6-31G(d,p) level of theory, which include a series of simple PDs for comparison. The data show that the structural arrangement close to the PD core is similar to that of N,N,N',N'-tetra-n-alkyl-p-phenylenediamines, including a planar arrangement of the atoms linked to the two PD nitrogen atoms. Thus, the effect of chain size on the oxidation potential appears to be caused primarily by a simple electronic effect. The calculations indicate considerable reorientation of the dendrimer side chains on oxidation, presumably caused by interactions between the positive charge centered at the core and the neighboring ester or amide dipoles. The relative ease of oxidation of TMePD and the lowest members of the series of the dendrimers can be reproduced theoretically only when solvation was included in the calculations. The DPV peak heights vary approximately as predicted from the Stokes-Einstein-Sutherland equation, but the variation of the relative effective radii with the size of the dendrimer is much larger than predicted from the radii obtained by the DFT calculations, that is, the dendrimers exist in solution mainly as aggregates.

  15. Hydroxyl ion addition to one-electron oxidized thymine: Unimolecular interconversion of C5 to C6 OH-adducts

    PubMed Central

    Adhikary, Amitava; Kumar, Anil; Heizer, Alicia N.; Palmer, Brian J.; Pottiboyina, Venkata; Liang, Yong; Wnuk, Stanislaw F.; Sevilla, Michael D.

    2013-01-01

    In this work, addition of OH− to one-electron oxidized thymidine (dThd) and thymine nucleotides in basic aqueous glasses is investigated. At pHs ca. 9–10 where the thymine base is largely deprotonated at N3, one-electron oxidation of the thymine base by Cl2•− at ca. 155 K results in formation of a neutral thyminyl radical, T(−H)•. Assignment to T(−H)• is confirmed by employing 15N substituted 5'-TMP. At pH ≥ ca. 11.5, formation of the 5-hydroxythymin-6-yl radical, T(5OH)•, is identified as a metastable intermediate produced by OH− addition to T(−H)• at C5 at ca. 155 K. Upon further annealing to ca. 170 K, T(5OH)• readily converts to the 6-hydroxythymin-5-yl radical, T(6OH)•. One-electron oxidation of N3-methyl-thymidine (N3-Me-dThd) by Cl2•− at ca. 155 K produces the cation radical (N3-Me-dThd•+) for which we find a pH dependent competition between deprotonation from the methyl group at C5 and addition of OH− to C5. At pH 7 the 5-methyl deprotonated species is found; however, at pH ca. 9, N3-Me-dThd•+ produces T(5OH)• that on annealing up to 180 K forms T(6OH)•. Through use of deuterium substitution at C5' and on the thymine base, i.e., specifically employing [5',5”-D,D]-5'-dThd, [5',5”-D,D]-5'-TMP, [CD3]-dThd and [CD3,6D]-dThd, we find unequivocal evidence for T(5OH)• formation and its conversion to T(6OH)•. The addition of OH− to the C5 position in T(−H)• and N3-Me-dThd•+ is governed by spin and charge localization. DFT calculations predict that the conversion of the “reducing” T(5OH)• to the “oxidizing” T(6OH)• occurs by a unimolecular OH group transfer from C5 to C6 in the thymine base. The T(5OH)• to T(6OH)• conversion is found to occur more readily for deprotonated dThd and its nucleotides than for N3-Me-dThd. In agreement, calculations predict that the deprotonated thymine base has a lower energy barrier (ca. 6 kcal/mol) for OH transfer than its corresponding N3-protonated thymine

  16. Nitric oxide reduction to ammonia by TiO₂ electrons in colloid solution via consecutive one-electron transfer steps.

    PubMed

    Goldstein, Sara; Behar, David; Rajh, Tijana; Rabani, Joseph

    2015-03-26

    The reaction mechanism of nitric oxide (NO) reduction by excess electrons on TiO2 nanoparticles (e(TiO2)(-)) has been studied under anaerobic conditions. TiO2 was loaded with 10-130 electrons per particle using γ-irradiation of acidic TiO2 colloid solutions containing 2-propanol. The study is based on time-resolved kinetics and reactants and products analysis. The reduction of NO by e(TiO2)(-) is interpreted in terms of competition between a reaction path leading to formation of NH3 and a path leading to N2O and N2. The proposed mechanism involves consecutive one-electron transfers of NO, and its reduction intermediates HNO, NH2O(•), and NH2OH. The results show that e(TiO2)(-) does not reduce N2O and N2. Second-order rate constants of e(TiO2)(-) reactions with NO (740 ± 30 M(-1) s(-1)) and NH2OH (270 ± 30 M(-1) s(-1)) have been determined employing the rapid-mixing stopped-flow technique and that with HNO (>1.3 × 10(6) M(-1) s(-1)) was derived from fitting the kinetic traces to the suggested reaction mechanism, which is discussed in detail.

  17. One-electron oxidation of an oxoiron(IV) complex to form an [O═FeV═NR]+ center.

    PubMed

    Van Heuvelen, Katherine M; Fiedler, Adam T; Shan, Xiaopeng; De Hont, Raymond F; Meier, Katlyn K; Bominaar, Emile L; Münck, Eckard; Que, Lawrence

    2012-07-24

    Oxoiron(V) species are postulated to be involved in the mechanisms of the arene cis-dihydroxylating Rieske dioxygenases and of bioinspired nonheme iron catalysts for alkane hydroxylation, olefin cis-dihydroxylation, and water oxidation. In an effort to obtain a synthetic oxoiron(V) complex, we report herein the one-electron oxidation of the S = 1 complex [Fe(IV)(O)(TMC)(NCCH(3))](2+) (1, where TMC is tetramethylcyclam) by treatment with tert -butyl hydroperoxide and strong base in acetonitrile to generate a metastable complex 2 at -44 °C, which has been characterized by UV-visible, resonance Raman, Mössbauer, and EPR methods. The defining spectroscopic characteristic of 2 is the unusual x/y anisotropy observed for the (57)Fe and (17)O A tensors associated with the high-valent Fe═O unit and for the (14)N A tensor of a ligand derived from acetonitrile. As shown by detailed density functional theory (DFT) calculations, the unusual x/y anisotropy observed can only arise from an iron center with substantially different spin populations in the d(xz) and d(yz) orbitals, which cannot correspond to an Fe(IV)═O unit but is fully consistent with an Fe(V) center, like that found for [Fe(V)(O)(TAML)](-) (where TAML is tetraamido macrocyclic ligand), the only well-characterized oxoiron(V) complex reported. Mass spectral analysis shows that the generation of 2 entails the addition of an oxygen atom to 1 and the loss of one positive charge. Taken together, the spectroscopic data and DFT calculations support the formulation of 2 as an iron(V) complex having axial oxo and acetylimido ligands, namely [Fe(V)(O)(TMC)(NC(O)CH(3))](+).

  18. One-electron oxidation of an oxoiron(IV) complex to form an [O═FeV═NR]+ center

    PubMed Central

    Van Heuvelen, Katherine M.; Fiedler, Adam T.; Shan, Xiaopeng; De Hont, Raymond F.; Meier, Katlyn K.; Bominaar, Emile L.; Münck, Eckard; Que, Lawrence

    2012-01-01

    Oxoiron(V) species are postulated to be involved in the mechanisms of the arene cis-dihydroxylating Rieske dioxygenases and of bioinspired nonheme iron catalysts for alkane hydroxylation, olefin cis-dihydroxylation, and water oxidation. In an effort to obtain a synthetic oxoiron(V) complex, we report herein the one-electron oxidation of the S = 1 complex [FeIV(O)(TMC)(NCCH3)]2+ (1, where TMC is tetramethylcyclam) by treatment with tert -butyl hydroperoxide and strong base in acetonitrile to generate a metastable complex 2 at -44 °C, which has been characterized by UV-visible, resonance Raman, Mössbauer, and EPR methods. The defining spectroscopic characteristic of 2 is the unusual x/y anisotropy observed for the 57Fe and 17O A tensors associated with the high-valent Fe═O unit and for the 14N A tensor of a ligand derived from acetonitrile. As shown by detailed density functional theory (DFT) calculations, the unusual x/y anisotropy observed can only arise from an iron center with substantially different spin populations in the dxz and dyz orbitals, which cannot correspond to an FeIV═O unit but is fully consistent with an FeV center, like that found for [FeV(O)(TAML)]- (where TAML is tetraamido macrocyclic ligand), the only well-characterized oxoiron(V) complex reported. Mass spectral analysis shows that the generation of 2 entails the addition of an oxygen atom to 1 and the loss of one positive charge. Taken together, the spectroscopic data and DFT calculations support the formulation of 2 as an iron(V) complex having axial oxo and acetylimido ligands, namely [FeV(O)(TMC)(NC(O)CH3)]+. PMID:22786933

  19. Solution Photophysics, One-Electron Photooxidation, and Photoinitiated Two-Electron Oxidation of Molybdenum(III) Complexes.

    PubMed

    Mohammed, Abdul K.; Isovitsch, Ralph A.; Maverick, Andrew W.

    1998-06-01

    Several six-coordinate Mo(III) complexes phosphoresce and undergo photooxidation in room-temperature solution. The phosphorescence of (Me(3)[9]aneN(3))MoX(3) (Me(3)[9]aneN(3) = 1,4,7-trimethyl-1,4,7-triazacyclononane) in CH(3)CN at room temperature occurs with the following maxima, lifetimes, and quantum yields: X = Cl, 1120 nm, 1.0 &mgr;s, and 6.1 x 10(-)(5); X = Br, 1130 nm, 0.80 &mgr;s, and 9.6 x 10(-)(5); and X = I, 1160 nm, 0.40 &mgr;s, and 1.2 x 10(-)(4), respectively. The phosphorescences are assigned to the {(2)E(g), (2)T(1g)} --> (4)A(2g) transition. Solutions of HB(Me(2)pz)(3)Mo(III)Cl(3)(-) Me(2)pzH = 3,5-dimethylpyrazole) in CH(3)CN, and solid MoCl(3)(py)(3) and (Me(3)[9]aneN(3))WCl(3), also phosphoresce. (Me(3)[9]aneN(3))MoX(3) (X = Cl, Br, I) complexes undergo reversible one-electron photooxidation upon irradiation in the presence of acceptors such as TCNE and chloranil. (Me(3)[9]aneN(3))MoX(3) (X = Br, I only) are photooxidized irreversibly to [(Me(3)[9]aneN(3))Mo(IV)X(3)](+) by C(NO(2))(4) in CH(3)CN. In CH(3)CN-H(2)O (1:1 v/v), photoinitiated two-electron oxidation occurs: the primary photoproduct is Mo(IV), which disproportionates spontaneously to form [(Me(3)[9]aneN(3))Mo(V)OX(2)](+).

  20. DNA sequence context as a determinant of the quantity and chemistry of guanine oxidation produced by hydroxyl radicals and one-electron oxidants.

    PubMed

    Margolin, Yelena; Shafirovich, Vladimir; Geacintov, Nicholas E; DeMott, Michael S; Dedon, Peter C

    2008-12-19

    DNA sequence context has emerged as a critical determinant of the location and quantity of nucleobase damage caused by many oxidizing agents. However, the complexity of nucleobase and 2-deoxyribose damage caused by strong oxidants such as ionizing radiation and the Fenton chemistry of Fe2+-EDTA/H2O2 poses a challenge to defining the location of nucleobase damage and the effects of sequence context on damage chemistry in DNA. To address this problem, we developed a gel-based method that allows quantification of nucleobase damage in oxidized DNA by exploiting Escherichia coli exonuclease III to remove fragments containing direct strand breaks and abasic sites. The rigor of the method was verified in studies of guanine oxidation by photooxidized riboflavin and nitrosoperoxycarbonate, for which different effects of sequence context have been demonstrated by other approaches (Margolin, Y., Cloutier, J. F., Shafirovich, V., Geacintov, N. E., and Dedon, P. C. (2006) Nat. Chem. Biol. 2, 365-366). Using duplex oligodeoxynucleotides containing all possible three-nucleotide sequence contexts for guanine, the method was used to assess the role of DNA sequence context in hydroxyl radical-induced guanine oxidation associated with gamma-radiation and Fe2+-EDTA/H2O2. The results revealed both differences and similarities for G oxidation by hydroxyl radicals and by one-electron oxidation by riboflavin-mediated photooxidation, which is consistent with the predominance of oxidation pathways for hydroxyl radicals other than one-electron oxidation to form guanine radical cations. Although the relative quantities of G oxidation produced by hydroxyl radicals were more weakly correlated with sequence-specific ionization potential than G oxidation produced by riboflavin, damage produced by both hydroxyl radical generators and riboflavin within two- and three-base runs of G showed biases in location that are consistent with a role for electron transfer in defining the location of the damage

  1. π-Radical to σ-Radical Tautomerization in One-Electron-Oxidized 1-Methylcytosine and Its Analogs.

    PubMed

    Adhikary, Amitava; Kumar, Anil; Bishop, Casandra T; Wiegand, Tyler J; Hindi, Ragda M; Adhikary, Ananya; Sevilla, Michael D

    2015-09-03

    In this work, iminyl σ-radical formation in several one-electron-oxidized cytosine analogs, including 1-MeC, cidofovir, 2'-deoxycytidine (dCyd), and 2'-deoxycytidine 5'-monophosphate (5'-dCMP), were investigated in homogeneous, aqueous (D2O or H2O) glassy solutions at low temperatures by employing electron spin resonance (ESR) spectroscopy. Upon employing density functional theory (DFT) (DFT/B3LYP/6-31G* method), the calculated hyperfine coupling constant (HFCC) values of iminyl σ-radical agree quite well with the experimentally observed ones, thus confirming its assignment. ESR and DFT studies show that the cytosine iminyl σ-radical is a tautomer of the deprotonated cytosine π-cation radical [cytosine π-aminyl radical, C(N4-H)(•)]. Employing 1-MeC samples at various pHs ranging from ca. 8 to 11, ESR studies show that the tautomeric equilibrium between C(N4-H)(•) and the iminyl σ-radical at low temperature is too slow to be established without added base. ESR and DFT studies agree that, in the iminyl σ-radical, the unpaired spin is localized on the exocyclic nitrogen (N4) in an in-plane pure p-orbital. This gives rise to an anisotropic nitrogen hyperfine coupling (Azz = 40 G) from N4 and a near isotropic β-nitrogen coupling of 9.7 G from the cytosine ring nitrogen at N3. Iminyl σ-radical should exist in its N3-protonated form, as the N3-protonated iminyl σ-radical is stabilized in solution by over 30 kcal/mol (ΔG = -32 kcal/mol) over its conjugate base, the N3-deprotonated form. This is the first observation of an isotropic β-hyperfine ring nitrogen coupling in an N-centered DNA radical. Our theoretical calculations predict that the cytosine iminyl σ-radical can be formed in double-stranded DNA by a radiation-induced ionization-deprotonation process that is only 10 kcal/mol above the lowest energy path.

  2. One electron oxidation potential as a predictor of rate constants of N-containing compounds with carbonate radical and triplet excited state organic matter.

    PubMed

    Arnold, William A

    2014-04-01

    Photo-generated transient species, such as the carbonate radical and triplet excited state natural organic matter, mediate the oxidation of pollutants in various sunlit or artificially irradiated systems. In this work, one-electron oxidation potentials for 70 nitrogen-containing compounds were computed, and literature data were used to develop quantitative structure-activity relationships (QSARs) for prediction of the second order reaction rate constants with these two oxidants. For carbonate radical, separate QSARs were necessary for compounds with and without resonance stabilization of the resulting radical, and predicted rate constants were, on average, within a factor of three of experimental values. With the limited data set available, results suggest that one-electron oxidation potential is also a viable descriptor variable for predictions of rate constants with triplet excited states.

  3. The structure of a one-electron oxidized Mn(iii)-bis(phenolate)dipyrrin radical complex and oxidation catalysis control via ligand-centered redox activity.

    PubMed

    Lecarme, Laureline; Chiang, Linus; Moutet, Jules; Leconte, Nicolas; Philouze, Christian; Jarjayes, Olivier; Storr, Tim; Thomas, Fabrice

    2016-10-18

    The tetradentate ligand dppH3, which features a half-porphyrin and two electron-rich phenol moieties, was prepared and chelated to manganese. The mononuclear Mn(iii)-dipyrrophenolate complex 1 was structurally characterized. The metal ion lies in a square pyramidal environment, the apical position being occupied by a methanol molecule. Complex 1 displays two reversible oxidation waves at 0.00 V and 0.47 V vs. Fc(+)/Fc, which are assigned to ligand-centered processes. The one-electron oxidized species 1+ SbF6- was crystallized, showing an octahedral Mn(iii) center with two water molecules coordinated at both apical positions. The bond distance analysis and DFT calculations disclose that the radical is delocalized over the whole aromatic framework. Complex 1+ SbF6- exhibits an Stot = 3/2 spin state due to the antiferromagnetic coupling between Mn(iii) and the ligand radical. The zero field splitting parameters are D = 1.6 cm(-1), E/D = 0.18(1), g⊥ = 1.99 and g∥ = 1.98. The dication 12+ is an integer spin system, which is assigned to a doubly oxidized ligand coordinated to a Mn(iii) metal center. Both 1 and 1+ SbF6- catalyze styrene oxidation in the presence of PhIO, but the nature of the main reaction product is different. Styrene oxide is the main reaction product when using 1, but phenylacetaldehyde is formed predominantly when using 1+ SbF6-. We examined the ability of complex 1+ SbF6- to catalyze the isomerization of styrene oxide and found that it is an efficient catalyst for the anti-Markovnikov opening of styrene oxide. The formation of phenylacetaldehyde from styrene therefore proceeds in a tandem E-I (epoxidation-isomerization) mechanism in the case of 1+ SbF6-. This is the first evidence of control of the reactivity for styrene oxidation by changing the oxidation state of a catalyst based on a redox-active ligand.

  4. DNA damage by the sulfate radical anion: hydrogen abstraction from the sugar moiety versus one-electron oxidation of guanine.

    PubMed

    Roginskaya, Marina; Mohseni, Reza; Ampadu-Boateng, Derrick; Razskazovskiy, Yuriy

    2016-07-01

    The products of oxidative damage to double-stranded (ds) DNA initiated by photolytically generated sulfate radical anions SO4(•-) were analyzed using reverse-phase (RP) high-performance liquid chromatography (HPLC). Relative efficiencies of two major pathways were compared: production of 8-oxoguanine (8oxoG) and hydrogen abstraction from the DNA 2-deoxyribose moiety (dR) at C1,' C4,' and C5' positions. The formation of 8oxoG was found to account for 87% of all quantified lesions at low illumination doses. The concentration of 8oxoG quickly reaches a steady state at about one 8oxoG per 100 base pairs due to further oxidation of its products. It was found that another guanine oxidation product identified as 2-amino-5-(2'-alkylamino)-4H-imidazol-4-one (X) was released in significant quantities from its tentative precursor 2-amino-5-[(2'-deoxy-β-d-erythro-pentofuranosyl)amino]-4H-imidazol-4-one (dIz) upon treatment with primary amines in neutral solutions. The linear dose dependence of X release points to the formation of dIz directly from guanine and not through oxidation of 8oxoG. The damage to dR was found to account for about 13% of the total damage, with majority of lesions (33%) originating from the C4' oxidation. The contribution of C1' oxidation also turned out to be significant (17% of all dR damages) despite of the steric problems associated with the abstraction of the C1'-hydrogen. However, no evidence of base-to-sugar free valence transfer as a possible alternative to direct hydrogen abstraction at C1' was found.

  5. Computational prediction of one-electron reduction potentials and acid dissociation constants for guanine oxidation intermediates and products.

    PubMed

    Psciuk, Brian T; Schlegel, H Bernhard

    2013-08-15

    Reduction potentials and pK(a) values were calculated for intermediates and products along three major pathways for guanine oxidation using the B3LYP and CBS-QB3 levels of theory with the SMD implicit solvation model. N-methylated nucleobases were used as models for nucleoside species. Ensemble averaged reduction potentials at pH 7 (E7) were obtained by combining calculated standard reduction potentials with calculated pKa values in addition to accounting for tautomerization energies. Calculated pK(a) values are reasonable based on experimental estimates and chemical intuition. Pathway A leads to guanidinohydantoin (Gh) and spiroiminodihydantoin (Sp). The first step is the oxidation of 8-oxoguanine which proceeds by the loss of an electron followed by the loss of two protons and loss of another electron, yielding 8-oxopurine. The calculated E7 values for the remaining intermediates and products are at least 0.3 V higher than that of guanine, indicating that further oxidation of these species is unlikely. Pathway B leads to two formamidopyrimidine isomers (FAPyG and 2,5FAPyG). Species along this pathway have calculated reduction potentials that are much lower than the oxidation potential for guanine and would likely be very short-lived in an oxidatively stressed environment. Pathway C leads to reduced spiroiminodihydantoin and 5-carboxamido-5-formamido-2-iminohydantoin (2Ih). Similar to pathway A, the calculated reduction potentials for species along this pathway are at least 0.4 V higher than that of guanine.

  6. Anodic preparation of [Re2Cp2(CO)6]2+: a dimeric dication that provides the powerful one-electron oxidant [ReCp(CO)3]+.

    PubMed

    Chong, Daesung; Nafady, Ayman; Costa, Paulo Jorge; Calhorda, Maria José; Geiger, William E

    2005-11-16

    The half-sandwich piano-stool compounds Re(eta5-C5R5)(CO)3 (1, R = H; or 2, R = Me) are oxidized to the corresponding 17-electron Re(II) cations at glassy carbon anodes in CH2Cl2/[NBu4][B(C6F5)4]. Despite the very strongly positive E1/2 values of the couples (1.16 V for 1/1+ and 0.91 V for 2/2+ vs ferrocene/ferrocenium), the radical cations are persistent in this medium and exist in equilibrium with the corresponding dimeric dications, which may be cathodically reduced back to the neutral starting material. DFT calculations show that the dimer of 1+ achieves its stability through formation of a single long (almost 3.3 A) Re-Re bond made possible when the HOMO in 1 is rehybridized away from the metal in the one-electron oxidation process. The pure salts [1][B(C6F5)4]2 and [2][B(C6F5)4]2 were isolated by preparative anodic electrochemistry. The former may be used for storage of the very strong one-electron oxidant 1+, which was used to prepare a number of oxidation products as their [B(C6F5)4]- salts.

  7. Detailed Evaluation of the Geometric and Electronic Structures of One-electron Oxidized Group 10 (Ni, Pd, and Pt) Metal(II)-(Disalicylidene)diamine Complexes

    PubMed Central

    Stack, T. Daniel P.

    2009-01-01

    The geometric and electronic structures of a series of one-electron oxidized group 10 metal salens (Ni, Pd, Pt) have been investigated in solution and in the solid state. Ni (1) and Pd (2) complexes of the tetradentate salen ligand N,N’-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine (H2Salcn) have been examined along with the Pt (3) complex of the salen ligand N,N’-bis(3,5-di-tert-butylsalicylidene)-1,2-ethylenediamine (H2Salen). All three oxidized compounds exist as ligand radical species in solution and in the solid state. The solid state structures of [1]+ and [3]+ exhibit a symmetric coordination sphere contraction relative to the neutral forms. By contrast, the coordination sphere of the Pd derivative [2]+ exhibits a pronounced asymmetry in the solid state. In solution, the oxidized derivatives display intense low-energy NIR transitions consistent with their classification as ligand radical compounds. Interestingly, the degree of communication between the phenolate moieties depends strongly on the central metal ion, within the Ni, Pd, and Pt series. Electrochemical measurements and UV-Vis-NIR spectroscopy, in conjunction with DFT calculations provide insights into the degree of delocalization of the one-electron hole in these systems. The Pd complex [2]+ is the least delocalized and is best described as a borderline Class II/III intervalence complex based on the Robin-Day classification system. The Ni [1]+ and Pt [3]+ analogues are Class III (fully delocalized) intervalence compounds. Delocalization is dependent on the electronic coupling between the redox-active phenolate ligands, mediated by overlap between the formally filled metal dxz orbital and the appropriate ligand molecular orbital. The degree of coupling increases in the order Pd < Ni < Pt for the one-electron oxidized group 10 metal salens. PMID:19639970

  8. Detailed evaluation of the geometric and electronic structures of one-electron oxidized group 10 (Ni, Pd, and Pt) metal(II)-(disalicylidene)diamine complexes.

    PubMed

    Shimazaki, Yuichi; Stack, T Daniel P; Storr, Tim

    2009-09-07

    The geometric and electronic structures of a series of one-electron oxidized group 10 metal salens (Ni, Pd, Pt) have been investigated in solution and in the solid state. Ni (1) and Pd (2) complexes of the tetradentate salen ligand N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine (H(2)Salcn) have been examined along with the Pt (3) complex of the salen ligand N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-ethylenediamine (H(2)Salen). All three oxidized compounds exist as ligand radical species in solution and in the solid state. The solid state structures of [1](+) and [3](+) exhibit a symmetric coordination sphere contraction relative to the neutral forms. By contrast, the coordination sphere of the Pd derivative [2](+) exhibits a pronounced asymmetry in the solid state. In solution, the oxidized derivatives display intense low-energy NIR transitions consistent with their classification as ligand radical compounds. Interestingly, the degree of communication between the phenolate moieties depends strongly on the central metal ion, within the Ni, Pd, and Pt series. Electrochemical measurements and UV-vis-NIR spectroscopy, in conjunction with density functional theory calculations provide insights into the degree of delocalization of the one-electron hole in these systems. The Pd complex [2](+) is the least delocalized and is best described as a borderline Class II/III intervalence complex based on the Robin-Day classification system. The Ni [1](+) and Pt [3](+) analogues are Class III (fully delocalized) intervalence compounds. Delocalization is dependent on the electronic coupling between the redox-active phenolate ligands, mediated by overlap between the formally filled metal d(xz) orbital and the appropriate ligand molecular orbital. The degree of coupling increases in the order Pd < Ni < Pt for the one-electron oxidized group 10 metal salens.

  9. One-electron oxidation pathway of thiols by peroxynitrite in biological fluids: bicarbonate and ascorbate promote the formation of albumin disulphide dimers in human blood plasma.

    PubMed Central

    Scorza, G; Minetti, M

    1998-01-01

    Recent studies have shown that peroxynitrite oxidizes thiol groups through competing one- and two-electron pathways. The two-electron pathway is mediated by the peroxynitrite anion and prevails quantitatively over the one-electron pathway, which is mediated by peroxynitrous acid or a reactive species derived from it. In CO2-containing fluids the oxidation of thiols might follow a different mechanism owing to the rapid formation of a different oxidant, the nitrosoperoxycarbonate anion (ONOOCO2(-)). Here we present evidence that in blood plasma peroxynitrite induces the formation of a disulphide cross-linked protein identified by immunological (anti-albumin antibodies) and biochemical criteria (peptide mapping) as a dimer of serum albumin. The albumin dimer did not form in plasma devoid of CO2 and its formation was enhanced by ascorbate. However, analysis of thiol groups showed that reconstituting dialysed plasma with NaHCO3 protected protein thiols against the oxidation mediated by peroxynitrite and that the simultaneouspresence of ascorbate provided further protection. Ascorbate alone did not protect thiol groups from peroxynitrite-mediated oxidation. ESR spin-trapping studies with N-t-butyl-alpha-phenylnitrone (PBN) revealed that peroxynitrite induced the formation of protein thiyl radicals and their intensity was markedly decreased by plasma dialysis and restored by reconstitution with NaHCO3. PBN completely inhibited the formation of albumin dimer. Moreover, the addition of iron-diethyldithiocarbamate to plasma demonstrated that peroxynitrite induced the formation of protein S-nitrosothiols and/or S-nitrothiols. Our results are consistent with the hypothesis that NaHCO3 favours the one-electron oxidation of thiols by peroxynitrite with formation of thiyl radicals, ;NO2, and RSNOx. Thiyl radicals, in turn, are involved in chain reactions by which thiols are oxidized to disulphides. PMID:9425126

  10. A manganese(V)-oxo π-cation radical complex: influence of one-electron oxidation on oxygen-atom transfer.

    PubMed

    Prokop, Katharine A; Neu, Heather M; de Visser, Sam P; Goldberg, David P

    2011-10-12

    One-electron oxidation of Mn(V)-oxo corrolazine 2 affords 2(+), the first example of a Mn(V)(O) π-cation radical porphyrinoid complex, which was characterized by UV-vis, EPR, LDI-MS, and DFT methods. Access to 2 and 2(+) allowed for a direct comparison of their reactivities in oxygen-atom transfer (OAT) reactions. Both complexes are capable of OAT to PPh(3) and RSR substrates, and 2(+) was found to be a more potent oxidant than 2. Analysis of rate constants and activation parameters, together with DFT calculations, points to a concerted OAT mechanism for 2(+) and 2 and indicates that the greater electrophilicity of 2(+) likely plays a dominant role in enhancing its reactivity. These results are relevant to comparisons between Compound I and Compound II in heme enzymes.

  11. The mechanism of oxidative halophenol dehalogenation by Amphitrite ornata dehaloperoxidase is initiated by H2O2 binding and involves two consecutive one-electron steps: role of ferryl intermediates.

    PubMed

    Osborne, Robert L; Coggins, Michael K; Raner, Gregory M; Walla, Mike; Dawson, John H

    2009-05-26

    The enzymatic globin, dehaloperoxidase (DHP), from the terebellid polychaete Amphitrite ornata is designed to catalyze the oxidative dehalogenation of halophenol substrates. In this study, the ability of DHP to catalyze this reaction by a mechanism involving two consecutive one-electron steps via the normal order of addition of the oxidant cosubstrate (H(2)O(2)) before organic substrate [2,4,6-trichlorophenol (TCP)] is demonstrated. Specifically, 1 equiv of H(2)O(2) will fully convert 1 equiv of TCP to 2,6-dichloro-1,4-benzoquinone, implicating the role of multiple ferryl [Fe(IV)O] species. A significant amount of heterolytic cleavage of the O-O bond of cumene hydroperoxide, consistent with transient formation of a Compound I [Fe(IV)O/porphyrin pi-cation radical] species, is observed upon its reaction with ferric DHP. In addition, a more stable high-valent Fe(IV)O-containing DHP intermediate [Compound II (Cpd II) or Compound ES] is characterized by UV-visible absorption and magnetic circular dichroism spectroscopy. Spectral similarities are seen between this intermediate and horse heart myoglobin Cpd II. It is also shown in single-turnover experiments that the DHP Fe(IV)O intermediate is an active oxidant in halophenol oxidative dehalogenation. Furthermore, reaction of DHP with 4-chlorophenol leads to a dimeric product. The results presented herein are consistent with a normal peroxidase order of addition of the oxidant cosubstrate (H(2)O(2)) followed by organic substrate (TCP) and indicate that the enzymatic mechanism of DHP-catalyzed oxidative halophenol dehalogenation involves two consecutive one-electron steps with a dissociable radical intermediate.

  12. Detection of Structural Changes upon One-Electron Oxidation and Reduction of Stilbene Derivatives by Time-Resolved Resonance Raman Spectroscopy during Pulse Radiolysis and Theoretical Calculations.

    PubMed

    Fujitsuka, Mamoru; Cho, Dae Won; Choi, Jungkweon; Tojo, Sachiko; Majima, Tetsuro

    2015-07-02

    Stilbene (St) derivatives have been investigated for many years because of their interesting photochemical reactions such as cis-trans isomerization in the excited states and charged states and their relation to poly(p-phenylenevinylene)s. To clarify their charged state properties, structural information is indispensable. In the present study, radical cations and radical anions of St derivatives were investigated by radiation chemical methods. Absorption spectra of radical ion states were obtained by transient absorption measurements during pulse radiolysis; theoretical calculations that included the solvent effect afforded reasonable assignments. The variation in the peak position was explained by using HOMO and LUMO energy levels. Structural changes upon one-electron oxidation and reduction were detected by time-resolved resonance Raman measurements during pulse radiolysis. Significant downshifts were observed with the CC stretching mode of the ethylenic groups, indicative of the decrease in the bonding order. It was confirmed that the downshifts observed with reduction were larger than those with oxidation. On the other hand, the downshift caused by oxidation depends significantly on the electron-donating or electron-withdrawing nature of the substituents.

  13. Nitrite Reduction to Nitrous Oxide and Ammonia by TiO2 Electrons in a Colloid Solution via Consecutive One-Electron Transfer Reactions.

    PubMed

    Goldstein, Sara; Behar, David; Rajh, Tijana; Rabani, Joseph

    2016-04-21

    The mechanism of nitrite reduction by excess electrons on TiO2 nanoparticles (eTiO2(-)) was studied under anaerobic conditions. TiO2 was loaded with up to 75 electrons per particle, induced by γ-irradiation of acidic TiO2 colloid solutions containing 2-propanol. Time-resolved kinetics and material analysis were performed, mostly at 1.66 g L(-1) TiO2. At relatively low nitrite concentrations (R = [eTiO2(-)]o/[nitrite]o > 1.5), eTiO2(-) decays via two consecutive processes; at higher concentrations, only one decay step is observed. The stoichiometric ratio Δ[eTiO2(-)]/[nitrite]o of the faster process is about 2. This process involves the one-electron reduction of nitrite, forming the nitrite radical (k1 = (2.0 ± 0.2) × 10(6) M(-1) s(-1)), which further reacts with eTiO2(-) (k2) in competition with its dehydration to nitric oxide (NO) (k3). The ratios k2/k3 = (3.0 ± 0.5) × 10(3) M(-1) and k2 > 1 × 10(6) M(-1) s(-1) were derived from kinetic simulations and product analysis. The major product of this process is NO. The slower stage of the kinetics involves the reduction of NO by eTiO2(-), and the detailed mechanism of this process has been discussed in our earlier publication. The results reported in this study suggest that several intermediates, including NO and NH2OH, are adsorbed on the titanium nanoparticles and give rise to inverse dependency of the respective reaction rates on the TiO2 concentration. It is demonstrated that the reduction of nitrite by eTiO2(-) yields mainly N2O and NH3 via consecutive one-electron transfer reactions.

  14. One-electron oxidation of ferrocenes by short-lived N-oxyl radicals. The role of structural effects on the intrinsic electron transfer reactivities.

    PubMed

    Baciocchi, Enrico; Bietti, Massimo; D'Alfonso, Claudio; Lanzalunga, Osvaldo; Lapi, Andrea; Salamone, Michela

    2011-06-07

    A kinetic study of the one electron oxidation of substituted ferrocenes (FcX: X = H, COPh, COMe, CO(2)Et, CONH(2), CH(2)OH, Et, and Me(2)) by a series of N-oxyl radicals (succinimide-N-oxyl radical (SINO), maleimide-N-oxyl radical (MINO), 3-quinazolin-4-one-N-oxyl radical (QONO) and 3-benzotriazin-4-one-N-oxyl radical (BONO)), has been carried out in CH(3)CN. N-oxyl radicals were produced by hydrogen abstraction from the corresponding N-hydroxy derivatives by the cumyloxyl radical. With all systems, the rate constants exhibited a satisfactory fit to the Marcus equation allowing us to determine self-exchange reorganization energy values (λ(NO˙/NO(-))) which have been compared with those previously determined for the PINO/PINO(-) and BTNO/BTNO(-) couples. Even small modification of the structure of the N-oxyl radicals lead to significant variation of the λ(NO˙/NO(-)) values. The λ(NO˙/NO(-)) values increase in the order BONO < BTNO < QONO < PINO < SINO < MINO which do not parallel the order of the oxidation potentials. The higher λ(NO˙/NO(-)) values found for the MINO and SINO radicals might be in accordance with a lower degree of spin delocalization in the radicals MINO and SINO and charge delocalization in the anions MINO(-) and SINO(-) due to the absence of an aromatic ring in their structure.

  15. Calmodulin Methionine Residues are Targets For One-Electron Oxidation by Hydroxyl Radicals: Formation of S therefore N three-electron bonded Radical Complexes

    SciTech Connect

    Nauser, Thomas; Jacoby, Michael E.; Koppenol, Willem H.; Squier, Thomas C.; Schoneich, Christian

    2005-02-01

    The one-electron (1e) oxidation of organic sulfides and methionine (Met) constitutes an important reaction mechanism in vivo.1,2 Evidence for a Cu(II)-catalyzed oxidation of Met35 in the Alzheimer's disease -amyloid peptide was obtained,3 and, based on theoretical studies, Met radical cations were proposed as intermediates.4 In the structure of -amyloid peptide, the formation of Met radical cations appears to be facilitated by a preexisting close sulfur-oxygen (S-O) interaction between the Met35 sulfur and the carbonyl oxygen of the peptide bond C-terminal to Ile31.5 Substitution of Ile31 with Pro31 abolishes this S-O interaction,5 significantly reducing the ability of -amyloid to reduce Cu(II), and converts the neurotoxic wild-type -amyloid into a non-toxic peptide.6 The preexisting S-O bond characterized for wild-type -amyloid suggests that electron transfer from Met35 to Cu(II) is supported through stabilization of the Met radical cation by the electron-rich carbonyl oxygen, generating an SO-bonded7 sulfide radical cation (Scheme 1, reaction 1).5

  16. One-electron oxidation of diclofenac by human cytochrome P450s as a potential bioactivation mechanism for formation of 2'-(glutathion-S-yl)-deschloro-diclofenac.

    PubMed

    Boerma, Jan Simon; Vermeulen, Nico P E; Commandeur, Jan N M

    2014-01-25

    Reactive metabolites have been suggested to play a role in the idiosyncratic hepatotoxicity observed with diclofenac (DF). By structural identification of the GSH conjugates formed after P450-catalyzed bioactivation of DF, it was shown that three types of reactive intermediates were formed: p-benzoquinone imines, o-imine methide and arene-oxide. Recently, detection of 2'-(glutathion-S-yl)-deschloro-diclofenac (DDF-SG), resulting from chlorine substitution, suggested the existence of a fourth type of P450-dependent reactive intermediate whose inactivation by GSH is completely dependent on presence of glutathione S-transferase. In this study, fourteen recombinant cytochrome P450s and three flavin-containing monooxygenases were tested for their ability to produce oxidative DF metabolites and their corresponding GSH conjugates. Concerning the hydroxymetabolites and their GSH conjugates, results were consistent with previous studies. Unexpectedly, all tested recombinant P450s were able to form DDF-SG to almost similar extent. DDF-SG formation was found to be partially independent of NADPH and even occurred by heat-inactivated P450. However, product formation was fully dependent on both GSH and glutathione-S-transferase P1-1. DDF-SG formation was also observed in reactions with horseradish peroxidase in absence of hydrogen peroxide. Because DDF-SG was not formed by free iron, it appears that DF can be bioactivated by iron in hemeproteins. This was confirmed by DDF-SG formation by other hemeproteins such as hemoglobin. As a mechanism, we propose that DF is subject to heme-dependent one-electron oxidation. The resulting nitrogen radical cation, which might activate the chlorines of DF, then undergoes a GST-catalyzed nucleophilic aromatic substitution reaction in which the chlorine atom of the DF moiety is replaced by GSH.

  17. Nitric Oxide Reduction to Ammonia by TiO2 Electrons in Colloid Solution via Consecutive One-Electron Transfer Steps

    DOE PAGES

    Goldstein, Sara; Behar, David; Rajh, Tijana; ...

    2015-03-02

    The reaction mechanism of nitric oxide (NO) reduction by excess electrons on TiO2 nanoparticles (eTiO2–) has been studied under anaerobic conditions. TiO2 was loaded with 10–130 electrons per particle using γ-irradiation of acidic TiO2 colloid solutions containing 2-propanol. The study is based on time-resolved kinetics and reactants and products analysis. The reduction of NO by eTiO2– is interpreted in terms of competition between a reaction path leading to formation of NH3 and a path leading to N2O and N2. The proposed mechanism involves consecutive one-electron transfers of NO, and its reduction intermediates HNO, NH2O•, and NH2OH. The results show thatmore » eTiO2– does not reduce N2O and N2. Second-order rate constants of eTiO2– reactions with NO (740 ± 30 M–1 s–1) and NH2OH (270 ± 30 M–1 s–1) have been determined employing the rapid-mixing stopped-flow technique and that with HNO (>1.3 × 106 M–1 s–1) was derived from fitting the kinetic traces to the suggested reaction mechanism, which is discussed in detail.« less

  18. On the evolution of one-electron-oxidized deoxyguanosine in damaged DNA under physiological conditions: a DFT and ONIOM study on proton transfer and equilibrium.

    PubMed

    Galano, Annia; Alvarez-Idaboy, Juan Raúl

    2012-09-28

    Different deprotonation paths of the radical cation formed by one-electron oxidation of 2'-deoxyguanosine (2dG) sites in DNA have been studied using Density Functional Theory (M05-2X/6-31+G(d,p)) and ONIOM methodology (M05-2X/6-31+G(d,p):PM6) in conjunction with the SMD model to include the solvent effects. Models of increased complexity have been used ranging from the isolated nucleoside to a three unit double-stranded oligomer including the sugar units, the base pairing with cytidine, and the phosphate linkage. The reported results correspond to aqueous solution, at room temperature, and pH = 7.4. Under such conditions it was found that the proton transfer (PT) within the base pair is a minor path compared to the PT between the base pair and the surrounding water. It was also found that the deprotonation of ground-state 2dG˙(+) sites mainly yields C centered radicals in the sugar unit, with the largest populations corresponding to C4'˙ and C5'˙, followed by C3'˙. The different aspects of the presented theoretical study have been validated with experimental results.

  19. Copper-Catalyzed Aerobic Oxidations of Organic Molecules: Pathways for Two-Electron Oxidation with a Four-Electron Oxidant and a One-Electron Redox-Active Catalyst.

    PubMed

    McCann, Scott D; Stahl, Shannon S

    2015-06-16

    Selective oxidation reactions have extraordinary value in organic chemistry, ranging from the conversion of petrochemical feedstocks into industrial chemicals and polymer precursors to the introduction of heteroatom functional groups into pharmaceutical and agrochemical intermediates. Molecular oxygen (O2) would be the ideal oxidant for these transformations. Whereas many commodity-scale oxidations of simple hydrocarbon feedstocks employ O2 as an oxidant, methods for selective oxidation of more complex molecules bearing diverse functional groups are often incompatible with existing aerobic oxidation methods. The latter limitation provides the basis for our interest in the development of new catalytic transformations and the elucidation of mechanistic principles that underlie selective aerobic oxidation reactions. One challenge inherent in such methods is the incommensurate redox stoichiometry associated with the use of O2, a four-electron oxidant, in reactions that achieve two-electron oxidation of organic molecules. This issue is further complicated by the use of first-row transition-metal catalysts, which tend to undergo facile one-electron redox steps. In recent years, we have been investigating Cu-catalyzed aerobic oxidation reactions wherein the complexities just noted are clearly evident. This Account surveys our work in this area, which has emphasized three general classes of reactions: (1) single-electron-transfer reactions for oxidative functionalization of electron-rich substrates, such as arenes and heterocycles; (2) oxidative carbon-heteroatom bond-forming reactions, including C-H oxidations, that proceed via organocopper(III) intermediates; and (3) methods for aerobic oxidation of alcohols and amines that use Cu(II) in combination with an organic redox-active cocatalyst to dehydrogenate the carbon-heteroatom bond. These reaction classes demonstrate three different pathways to achieve two-electron oxidation of organic molecules via the cooperative

  20. Nitric Oxide Reduction to Ammonia by TiO2 Electrons in Colloid Solution via Consecutive One-Electron Transfer Steps

    SciTech Connect

    Goldstein, Sara; Behar, David; Rajh, Tijana; Rabani, Joseph

    2015-03-02

    The reaction mechanism of nitric oxide (NO) reduction by excess electrons on TiO2 nanoparticles (eTiO2) has been studied under anaerobic conditions. TiO2 was loaded with 10–130 electrons per particle using γ-irradiation of acidic TiO2 colloid solutions containing 2-propanol. The study is based on time-resolved kinetics and reactants and products analysis. The reduction of NO by eTiO2 is interpreted in terms of competition between a reaction path leading to formation of NH3 and a path leading to N2O and N2. The proposed mechanism involves consecutive one-electron transfers of NO, and its reduction intermediates HNO, NH2O•, and NH2OH. The results show that eTiO2 does not reduce N2O and N2. Second-order rate constants of eTiO2 reactions with NO (740 ± 30 M–1 s–1) and NH2OH (270 ± 30 M–1 s–1) have been determined employing the rapid-mixing stopped-flow technique and that with HNO (>1.3 × 106 M–1 s–1) was derived from fitting the kinetic traces to the suggested reaction mechanism, which is discussed in detail.

  1. One-Electron Oxidation of Methionine-Containing Dipeptides of Reverse Sequence: Sulfur versus Sulfoxide Characterized by IRMPD Spectroscopy and Static and Dynamics DFT Simulations.

    PubMed

    Gregori, Barbara; Guidoni, Leonardo; Crestoni, Maria Elisa; de Oliveira, Pedro; Houée-Levin, Chantal; Scuderi, Debora

    2017-02-24

    Gas-phase structural modifications induced by the oxidation of methionine of the two peptides of reverse sequence, methionine-valine (Met-Val) and valine-methionine (Val-Met), have been studied by mass-selected IR multiple photon dissociation (IRMPD) spectroscopy in the 800-2000 cm(-1) fingerprint range at the Centre Laser Infrarouge d'Orsay free-electron laser facility. The oxidation has been achieved by (•)OH radicals generated by γ radiolysis. IRMPD spectra were interpreted by static and harmonic DFT calculations and Born-Oppenheimer molecular dynamics simulations, which are employed to take into account all anharmonic and finite-temperature effects. The diagnostic signature of the sulfoxide group in the final products of Met-Val and Val-Met oxidations, which is missing in the spectra of native peptides, has been recorded. Evidence has also been gathered that a mixture of R and S isomers of close energies is formed. An interconversion between different isomers has been unveiled in the case of the oxidized Met-Val dipeptide.

  2. Effects of plant carotenoid spacers on the performance of a dye-sensitized solar cell using a chlorophyll derivative: Enhancement of photocurrent determined by one electron-oxidation potential of each carotenoid

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Feng; Matsuda, Arihiro; Koyama, Yasushi; Nagae, Hiroyoshi; Sasaki, Shin-ichi; Tamiaki, Hitoshi; Wada, Yuji

    2006-06-01

    Plant carotenoids (Cars) with 8-10 conjugated double bonds, having higher singlet energies than those of bacterial Cars with 9-13 conjugated double bonds, were added (by 20%) as redox spacers to a titania-based Grätzel-type solar cell using a chlorophyll derivative (PPB a) as the sensitizer. No clear indication of singlet-energy transfer from Car to PPB a was seen, but clear enhancement of photocurrent with the decreasing one electron-oxidation potential of Car was observed. An empirical equation correlating the increase in photocurrent to difference in one electron-oxidation potentials (PPB a minus Car) and the oscillator strength of Car is proposed.

  3. Seebeck coefficient of one electron

    SciTech Connect

    Durrani, Zahid A. K.

    2014-03-07

    The Seebeck coefficient of one electron, driven thermally into a semiconductor single-electron box, is investigated theoretically. With a finite temperature difference ΔT between the source and charging island, a single electron can charge the island in equilibrium, directly generating a Seebeck effect. Seebeck coefficients for small and finite ΔT are calculated and a thermally driven Coulomb staircase is predicted. Single-electron Seebeck oscillations occur with increasing ΔT, as one electron at a time charges the box. A method is proposed for experimental verification of these effects.

  4. One-Electron Oxidation of [M(P(t) Bu3 )2 ] (M=Pd, Pt): Isolation of Monomeric [Pd(P(t) Bu3 )2 ](+) and Redox-Promoted C-H Bond Cyclometalation.

    PubMed

    Troadec, Thibault; Tan, Sze-Yin; Wedge, Christopher J; Rourke, Jonathan P; Unwin, Patrick R; Chaplin, Adrian B

    2016-03-07

    Oxidation of zero-valent phosphine complexes [M(P(t) Bu3 )2 ] (M=Pd, Pt) has been investigated in 1,2-difluorobenzene solution using cyclic voltammetry and subsequently using the ferrocenium cation as a chemical redox agent. In the case of palladium, a mononuclear paramagnetic Pd(I) derivative was readily isolated from solution and fully characterized (EPR, X-ray crystallography). While in situ electrochemical measurements are consistent with initial one-electron oxidation, the heavier congener undergoes C-H bond cyclometalation and ultimately affords the 14 valence-electron Pt(II) complex [Pt(κ(2) PC -P(t) Bu2 CMe2 CH2 )(P(t) Bu3 )](+) with concomitant formation of [Pt(P(t) Bu3 )2 H](+) . © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  5. C5′- and C3′-sugar radicals produced via photo-excitation of one-electron oxidized adenine in 2′-deoxyadenosine and its derivatives

    PubMed Central

    Adhikary, Amitava; Becker, David; Collins, Sean; Koppen, Jessica; Sevilla, Michael D.

    2006-01-01

    We report that photo-excitation of one-electron-oxidized adenine [A(-H)•] in dAdo and its 2′-deoxyribonucleotides leads to formation of deoxyribose sugar radicals in remarkably high yields. Illumination of A(-H)• in dAdo, 3′-dAMP and 5′-dAMP in aqueous glasses at 143 K leads to 80-100% conversion to sugar radicals at C5′ and C3′. The position of the phosphate in 5′- and 3′-dAMP is observed to deactivate radical formation at the site of substitution. In addition, the pH has a crucial influence on the site of sugar radical formation; e.g. at pH ∼5, photo-excitation of A(-H)• in dAdo at 143 K produces mainly C5′• whereas only C3′• is observed at high pH ∼12. 13C substitution at C5′ in dAdo yields 13C anisotropic couplings of (28, 28, 84) G whose isotropic component 46.7 G identifies formation of the near planar C5′•. A β-13C 16 G isotropic coupling from C3′• is also found. These results are found to be in accord with theoretically calculated 13C couplings at C5′ [DFT, B3LYP, 6-31(G) level] for C5′• and C3′•. Calculations using time-dependent density functional theory [TD-DFT B3LYP, 6-31G(d)] confirm that transitions in the near UV and visible induce hole transfer from the base radical to the sugar group leading to sugar radical formation. PMID:16537838

  6. Multiple Proteases to Localize Oxidation Sites

    PubMed Central

    Gu, Liqing; Robinson, Renã A. S.

    2015-01-01

    Proteins present in cellular environments with high levels of reactive oxygen and nitrogen species and/or low levels of antioxidants are highly susceptible to oxidative post-translational modification (PTM). Irreversible oxidative PTMs can generate a complex distribution of modified protein molecules, recently termed as proteoforms. Using ubiquitin as a model system, we mapped oxidative modification sites using trypsin, Lys-C, and Glu-C peptides. Several M+16 Da proteoforms were detected as well as proteoforms that include other previously unidentified oxidative modifications. This work highlights the use of multiple protease digestions to give insights to the complexity of oxidative modifications possible in bottom-up analyses. PMID:25775238

  7. Oxidative damage in multiple sclerosis lesions.

    PubMed

    Haider, Lukas; Fischer, Marie T; Frischer, Josa M; Bauer, Jan; Höftberger, Romana; Botond, Gergö; Esterbauer, Harald; Binder, Christoph J; Witztum, Joseph L; Lassmann, Hans

    2011-07-01

    Multiple sclerosis is a chronic inflammatory disease of the central nervous system, associated with demyelination and neurodegeneration. The mechanisms of tissue injury are currently poorly understood, but recent data suggest that mitochondrial injury may play an important role in this process. Since mitochondrial injury can be triggered by reactive oxygen and nitric oxide species, we analysed by immunocytochemistry the presence and cellular location of oxidized lipids and oxidized DNA in lesions and in normal-appearing white matter of 30 patients with multiple sclerosis and 24 control patients without neurological disease or brain lesions. As reported before in biochemical studies, oxidized lipids and DNA were highly enriched in active multiple sclerosis plaques, predominantly in areas that are defined as initial or 'prephagocytic' lesions. Oxidized DNA was mainly seen in oligodendrocyte nuclei, which in part showed signs of apoptosis. In addition, a small number of reactive astrocytes revealed nuclear expression of 8-hydroxy-d-guanosine. Similarly, lipid peroxidation-derived structures (malondialdehyde and oxidized phospholipid epitopes) were seen in the cytoplasm of oligodendrocytes and some astrocytes. In addition, oxidized phospholipids were massively accumulated in a fraction of axonal spheroids with disturbed fast axonal transport as well as in neurons within grey matter lesions. Neurons stained for oxidized phospholipids frequently revealed signs of degeneration with fragmentation of their dendritic processes. The extent of lipid and DNA oxidation correlated significantly with inflammation, determined by the number of CD3 positive T cells and human leucocyte antigen-D expressing macrophages and microglia in the lesions. Our data suggest profound oxidative injury of oligodendrocytes and neurons to be associated with active demyelination and axonal or neuronal injury in multiple sclerosis.

  8. Theoretical study of one-electron-oxidized salen complexes of group 7 (Mn(iii), Tc(iii), and Re(iii)) and group 10 metals (Ni(ii), Pd(ii), and Pt(ii)) with the 3D-RISM-GMC-QDPT method: localized vs. delocalized ground and excited states in solution.

    PubMed

    Aono, Shinji; Nakagaki, Masayuki; Sakaki, Shigeyoshi

    2017-06-28

    One-electron oxidized salen complexes of Mn(iii) and Ni(ii) were recently reported to be unique mixed-valence compounds. Their electronic structures are sensitive to the salen ligand and solvation. We systematically investigated a series of one-electron oxidized salen complexes of group 7 metals (Mn(iii), Tc(iii), and Re(iii)) and their group 10 analogues (Ni(ii), Pd(ii), and Pt(ii)) using the general multi-configuration reference quasi-degenerate perturbation theory (GMC-QDPT) which was combined with the three-dimensional reference interaction site model self-consistent field theory (3D-RISM-SCF) to incorporate the solvation effect. The calculated absorption spectra and electronic structures agree with the experimental observation. The one-electron oxidized salen complexes of group 10 metals with a symmetrical salen ligand have a delocalized electronic structure belonging to class III (Robin-Day classification) in weakly polar solvents. The tendency for taking a delocalized electronic structure increases in the order Pd(ii) < Ni(ii) < Pt(ii). When the salen ligand is asymmetrical, the one-electron oxidized complexes have a localized electronic structure belonging to class II. The group 7 analogues of Mn(iii) and Tc(iii) have a localized electronic structure belonging to class II even in weakly polar solvents and even with a symmetrical salen ligand. However, the one-electron oxidized Re(iii) complex has no mixed-valence nature because one-electron oxidation occurs on the Re center. Theoretical study shows that the solvation effect plays a crucial role in determining the mixed-valence character, class II or III, and thereby its incorporation in the calculation is indispensable for correctly describing geometries, electronic structures, and the inter-valence absorption spectra of these complexes. The d orbital energy is one of the most important factors for determining the localization/delocalization electronic structures in these complexes. Detailed discussion of

  9. One-electron physics of the actinides

    NASA Astrophysics Data System (ADS)

    Toropova, A.; Marianetti, C. A.; Haule, K.; Kotliar, G.

    2007-10-01

    We present a detailed analysis of the one-electron physics of the actinides. Various linear muffin-tin orbital basis sets are analyzed in order to determine a robust bare Hamiltonian for the actinides. The hybridization between f and spd states is compared with the f-f hopping in order to understand the Anderson-like and Hubbard-like contributions to itineracy in the actinides. We show that both contributions decrease strongly as one moves from the light actinides to the heavy actinides, while the Anderson-like contribution dominates in all cases. A real-space analysis of the band structure shows that nearest-neighbor hopping dominates the physics in these materials. Finally, we discuss the implications of our results to the delocalization transition as a function of atomic number across the actinide series.

  10. Multiple hearth furnace for reducing iron oxide

    DOEpatents

    Brandon, Mark M [Charlotte, NC; True, Bradford G [Charlotte, NC

    2012-03-13

    A multiple moving hearth furnace (10) having a furnace housing (11) with at least two moving hearths (20) positioned laterally within the furnace housing, the hearths moving in opposite directions and each moving hearth (20) capable of being charged with at least one layer of iron oxide and carbon bearing material at one end, and being capable of discharging reduced material at the other end. A heat insulating partition (92) is positioned between adjacent moving hearths of at least portions of the conversion zones (13), and is capable of communicating gases between the atmospheres of the conversion zones of adjacent moving hearths. A drying/preheat zone (12), a conversion zone (13), and optionally a cooling zone (15) are sequentially positioned along each moving hearth (30) in the furnace housing (11).

  11. One-electron oxidation of 2-(4-methoxyphenyl)-2-methylpropanoic and 1-(4-methoxyphenyl)cyclopropanecarboxylic acids in aqueous solution. the involvement of radical cations and the influence of structural effects and pH on the side-chain fragmentation reactivity.

    PubMed

    Bietti, Massimo; Capone, Alberto

    2008-01-18

    A product and time-resolved kinetic study on the one-electron oxidation of 2-(4-methoxyphenyl)-2-methylpropanoic acid (2), 1-(4-methoxyphenyl)cyclopropanecarboxylic acid (3), and of the corresponding methyl esters (substrates 4 and 5, respectively) has been carried out in aqueous solution. With 2, no direct evidence for the formation of an intermediate radical cation 2*+ but only of the decarboxylated 4-methoxycumyl radical has been obtained, indicating either that 2*+ is not formed or that its decarboxylation is too fast to allow detection under the experimental conditions employed (k > 1 x 10(7) s(-1)). With 3, oxidation leads to the formation of the corresponding radical cation 3*+ or radical zwitterion -3*+ depending on pH. At pH 1.0 and 6.7, 3*+ and -3*+ have been observed to undergo decarboxylation as the exclusive side-chain fragmentation pathway with rate constants k = 4.6 x 10(3) and 2.3 x 10(4) s(-1), respectively. With methyl esters 4 and 5, direct evidence for the formation of the corresponding radical cations 4*+ and 5*+ has been obtained. Both radical cations have been observed to display a very low reactivity and an upper limit for their decay rate constants has been determined as k < 10(3) s(-1). Comparison between the one-electron oxidation reactions of 2 and 3 shows that the replacement of the C(CH3)2 moiety with a cyclopropyl group determines a decrease in decarboxylation rate constant of more than 3 orders of magnitude. This large difference in reactivity has been qualitatively explained in terms of three main contributions: substrate oxidation potential, stability of the carbon-centered radical formed after decarboxylation, and stereoelectronic effects. In basic solution, -3*+ and 5*+ have been observed to react with -OH in a process that is assigned to the -OH-induced ring-opening of the cyclopropane ring, and the corresponding second-order rate constants (k-OH) have been obtained. With -3*+, competition between decarboxylation and -OH

  12. Comparison of the One-electron Oxidations of CO-Bridged vs Unbridged Bimetallic Complexes: Electron-transfer Chemistry of Os2Cp2(CO)4 and Os2Cp*2(μ-CO)2(CO)2 (Cp = η5-C5H5, Cp* = η5-C5Me5)

    SciTech Connect

    Laws, Derek R.; Bullock, R. Morris; Lee, Richmond; Huang, Kuo-Wei; Geiger, William J.

    2014-09-22

    The one-electron oxidations of two dimers of half-sandwich osmium carbonyl complexes have been examined by electrochemistry, spectro-electrochemistry, and computational methods. The all-terminal carbonyl complex Os2Cp2(CO)4 (1, Cp = η5-C5H5) undergoes a reversible one-electron anodic reaction at E1/2 = 0.41 V vs ferrocene in CH2Cl2/0.05 M [NBu4][B(C6F5)4], giving a rare example of a metal-metal bonded radical cation unsupported by bridging ligands. The IR spectrum of 1+ is consistent with an approximately 1:1 mixture of anti and gauche structures for the 33 e- radical cation in which it has retained all-terminal bonding of the CO ligands. DFT calculations, including orbital-occupancy-perturbed Mayer bond-order analyses, show that the HOMOs of anti-1 and gauche-1 are metal-ligand delocalized. Removal of an electron from 1 has very little effect on the Os-Os bond order, accounting for the resistance of 1+ to heterolytic cleavage. The Os-Os bond distance is calculated to decrease by 0.10 Å and 0.06 Å as a consequence of one-electron oxidation of anti-1 and gauche-1, respectively. The CO-bridged complex Os2Cp*2(μ-CO)2(CO)2 (Cp* = η5-C5Me5), trans-2, undergoes a more facile oxidation, E1/2 = - 0.11 V, giving a persistent radical cation shown by solution IR analysis to preserve its bridged-carbonyl structure. However, ESR analysis of frozen solutions of 2+ is interpreted in terms of the presence of two isomers, most likely anti-2+ and trans-2+, at low temperature. Calculations show that the HOMO of trans-2 is highly delocalized over the metal-ligand framework, with the bridging carbonyls accounting for about half of the orbital makeup. The Os-Os bond order again changes very little with removal of an electron, and the Os-Os bond length actually undergoes minor shortening. Calculations suggest that the second isomer of 2+ has both the trans CO-bridged and the anti all-terminal CO structures. DRL and WEG acknowledge the support of the National Science Foundation under

  13. One-electron transfer reactions of the couple NAD. /NADH. [Pulse radiolysis

    SciTech Connect

    Grodkowski, J.; Neta, P.; Carlson, B.W.; Miller, L.

    1983-08-04

    One-electron transfer reactions involving nicotinamide-adenine dinucleotide in its oxidized and reducd forms (NAD./NADH) were studied by pulse radiolysis in aqueous solutions. One-electron oxidation of NADH by various phenoxyl radicals and phenothiazine cation radicals was found to take place with rate constants in the range of 10/sup 5/ to 10/sup 8/ M/sup -1/ s/sup -1/, depending on the redox potential of the oxidizing species. In all cases, NAD. is formed quantitatively with no indication for the existence of the protonated form (NADH/sup +/.). The spectrum of NAD., as well as the rates of oxidation of NADH by phenoxyl and by (chlorpromazine)/sup +/. were independent of pH between pH 4.5 and 13.5. Reaction of deuterated NADH indicated only a small kinetic isotope effect. All these findings point to an electron transfer mechanism. On the other hand, attempts to observe the reverse electron transfer, i.e., one-electron reduction of NAD. to NADH by radicals such as semiquinones, showed that k was less than 10/sup 4/ to 10/sup 5/ M/sup -1/ s/sup -1/, so that it was unobservable. Consequently, it was not possible to achieve equilibrium conditions which would have permitted the direct measurement of the redox potential for NAD./NADH. One-electron reduction of NAD. appears to be an unlikely process. 1 table.

  14. Oxidation of multiple methionine residues impairs rapid sodium channel inactivation

    PubMed Central

    Kassmann, Mario; Hansel, Alfred; Leipold, Enrico; Birkenbeil, Jan; Lu, Song-Qing; Hoshi, Toshinori; Heinemann, Stefan H.

    2010-01-01

    Reactive oxygen species (ROS) readily oxidize the sulfur-containing amino acids cysteine and methionine (Met). The impact of Met oxidation on the fast inactivation of the skeletal muscle sodium channel NaV1.4 expressed in human embryonic kidney cells was studied by applying the Met-preferring oxidant chloramine-T (ChT) or by irradiating the ROS-producing dye Lucifer Yellow in the patch pipettes. Both interventions dramatically slowed down inactivation of the sodium channels. Replacement of Met in the Ile-Phe-Met inactivation motif with Leu (M1305L) strongly attenuated the oxidizing effect on inactivation but did not eliminate it completely. Mutagenesis of conserved Met residues in the intracellular linkers connecting the membrane-spanning segments of the channel (M1469L and M1470L) also markedly diminished the oxidation sensitivity of the channel, while that of other conserved Met residues (442, 1139, 1154, 1316) were without any noticeable effect. The results of mutagenesis of results, assays of other NaV channel isoforms (NaV1.2, NaV1.5, NaV1.7) and the kinetics of the oxidation-induced removal of inactivation collectively indicate that multiple Met target residues need to be oxidized to completely impair inactivation. This arrangement using multiple Met residues confers a finely graded oxidative modulation of NaV channels and allows organisms to adapt to a variety of oxidative stress conditions, such as ischemic reperfusion. PMID:18369661

  15. Interactions between manganese oxides and multiple-ringed aromatic compounds

    SciTech Connect

    Whelan, G.; Sims, R.C.

    1992-08-01

    Objective is to determine whether Mn reductive dissolution can oxidize multiple-ringed aromatics, such as PAHs, in an oxic environment? Research indicated that certain PAHs (eg, dihydrodiols and diones that form free-radical intermediates) are susceptible to oxidation and polymerization. Over 14 days, 83, 76, 54, 70, and 20% of the Mn was reduced by 2,3-, 1,3-, and 1,4-naphthalenediol, quinizarin, and 1,4-naphthoquinone, respectively. 100, 100, and 65% of the first three PAHs were oxidized, respectively. Aromatics with diol functional groups were more easily oxidized than those with only dione groups. Relatively insoluble compounds like quinizarin can be oxidized; insoluble ``humic-like`` material precipitated, indicating a polymerization-humification process. Results suggest that electron transfer/organic release from the oxide surface is the rate-limiting step.

  16. Interactions between manganese oxides and multiple-ringed aromatic compounds

    SciTech Connect

    Whelan, G. ); Sims, R.C. . Dept. of Civil and Environmental Engineering)

    1992-08-01

    Objective is to determine whether Mn reductive dissolution can oxidize multiple-ringed aromatics, such as PAHs, in an oxic environment Research indicated that certain PAHs (eg, dihydrodiols and diones that form free-radical intermediates) are susceptible to oxidation and polymerization. Over 14 days, 83, 76, 54, 70, and 20% of the Mn was reduced by 2,3-, 1,3-, and 1,4-naphthalenediol, quinizarin, and 1,4-naphthoquinone, respectively. 100, 100, and 65% of the first three PAHs were oxidized, respectively. Aromatics with diol functional groups were more easily oxidized than those with only dione groups. Relatively insoluble compounds like quinizarin can be oxidized; insoluble ''humic-like'' material precipitated, indicating a polymerization-humification process. Results suggest that electron transfer/organic release from the oxide surface is the rate-limiting step.

  17. Oxidative stress and proteasome inhibitors in multiple myeloma.

    PubMed

    Lipchick, Brittany C; Fink, Emily E; Nikiforov, Mikhail A

    2016-03-01

    Multiple myeloma is a form of plasma cell neoplasm that accounts for approximately 10% of all hematological malignancies. Recently, several novel drugs have been discovered that almost doubled the overall survival of multiple myeloma patients. One of these drugs, the first-in-class proteasome inhibitor bortezomib (Velcade) has demonstrated remarkable response rates in multiple myeloma patients, and yet, currently this disease remains incurable. The major factor undermining the success of multiple myeloma treatment is a rapidly emerging resistance to the available therapy. Thus, the development of stand-alone or adjuvant anti-myeloma agents becomes of paramount importance. Overproduction of intracellular reactive oxygen species (ROS) often accompanies malignant transformation due to oncogene activation and/or enhanced metabolism in tumor cells. As a result, these cells possess higher levels of ROS and lower levels of antioxidant molecules compared to their normal counterparts. Unbalanced production of ROS leads to oxidative stress which, if left unchecked, could be toxic for the cell. In multiple myeloma cells where high rates of immunoglobulin synthesis is an additional factor contributing to overproduction of ROS, further induction of oxidative stress can be an effective strategy to cope with this disease. Here we will review the available data on the role of oxidative stress in the cytotoxicity of proteasome inhibitors and the use of ROS-inducing compounds as anti-myeloma agents. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. One-electron images in real space: natural adaptive orbitals.

    PubMed

    Menéndez, Marcos; Álvarez Boto, Roberto; Francisco, Evelio; Martín Pendás, Ángel

    2015-04-30

    We introduce a general procedure to construct a set of one-electron functions in chemical bonding theory, which remain physically sound both for correlated and noncorrelated electronic structure descriptions. These functions, which we call natural adaptive orbitals, decompose the n-center bonding indices used in real space theories of the chemical bond into one-electron contributions. For the n = 1 case, they coincide with the domain natural orbitals used in domain-averaged Fermi hole analyses. We examine their interpretation in the two-center case, and show how they behave and evolve in simple cases. Orbital pictures obtained through this technique converge onto the chemist's molecular orbital toolbox if electron correlation may be ignored, and provide new insight if it may not.

  19. Oxidative modification of serum proteins in multiple sclerosis.

    PubMed

    Sadowska-Bartosz, Izabela; Adamczyk-Sowa, Monika; Galiniak, Sabina; Mucha, Sebastian; Pierzchala, Krystyna; Bartosz, Grzegorz

    2013-11-01

    Multiple sclerosis (MS) has been demonstrated to involve oxidative stress and augmented glycoxidation. In this study, several markers of protein oxidative damage and glycoxidation have been compared in 14 relapsing remittent in MS (RRMS) patients without immunomodifying treatment, 10 patients in clinical relapse, and clinically stable patient groups treated with interferon β 1a (18) , β 1b (19) and glatiramer acetate (GA; 6) in relation to healthy subjects (12). The glycophore content was increased in RRSM patients without treatment and in patients treated with GA. The level of advanced protein oxidation products (AOPP) was increased in RRSM patients without treatment and in patients with clinical relapse. The level of protein carbonyls was elevated in RRSM patients without treatment and in patients treated with interferon β 1b. The levels of dityrosine level and N'-formylkynureine were elevated in RRSM patients without treatment while serum protein thiol groups were decreased in RRSM patients in clinical relapse as well as RRMS patients treated with interferon β 1a. Several markers of protein modification showed correlation with the C-reactive protein level and white blood cell count, suggesting that oxidative protein modifications are linked to the inflammatory processes in MS. Results of this study confirm the occurrence of protein oxidative and glycoxidative damage in MS and show that spectrophotometric and fluorimetric markers of this damage, especially the AOPP level, may be useful in monitoring oxidative stress in the course of therapy of MS.

  20. Oxygen dependency of one-electron reactions generating ascorbate radicals and hydrogen peroxide from ascorbic acid.

    PubMed

    Boatright, William L

    2016-04-01

    The effect of oxygen on the two separate one-electron reactions involved in the oxidation of ascorbic acid was investigated. The rate of ascorbate radical (Asc(-)) formation (and stability) was strongly dependent on the presence of oxygen. A product of ascorbic acid oxidation was measurable levels of hydrogen peroxide, as high as 32.5 μM from 100 μM ascorbic acid. Evidence for a feedback mechanism where hydrogen peroxide generated during the oxidation of ascorbic acid accelerates further oxidation of ascorbic acid is also presented. The second one-electron oxidation reaction of ascorbic acid leading to the disappearance of Asc(-) was also strongly inhibited in samples flushed with argon. In the range of 0.05-1.2 mM ascorbic acid, maximum levels of measurable hydrogen peroxide were achieved with an initial concentration of 0.2 mM ascorbic acid. Hydrogen peroxide generation was greatly diminished at ascorbic acid levels of 0.8 mM or above. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Effective one-electron approaches to calculate high harmonic generation

    NASA Astrophysics Data System (ADS)

    Rohringer, Nina; Santra, Robin

    2006-05-01

    The single-active electron approach (SAE) is frequently applied to calculate high harmonic generation in atoms and consists in solving a one-particle Schr"odinger equation in an appropriate model potential. As an ad hoc approach it is difficult to be systematically improved. Starting with the time-dependent configuration interaction singles (TDCIS) technique we derive a new class of effective one-electron approaches. The resulting one-electron equations are in general non-local and non-unitary. A local approximation to TDCIS can be derived by restricting the total many-body Hamiltonian to a local mean-field Hamiltonian (those usually used in SAE calculations). The resulting equations are similar to traditional SAE approaches but include an additional term which destroys the unitarity of the time-evolution. We show that this correction term is essential and improves on traditional SAE approaches. Numerical tests show that this improved SAE method gives dipole-moments in better agreement with exact results than time-dependent Hartree Fock. The test system is a one-dimensional model of helium which allows for a straightforward numerical solution and therefore provides a benchmark to assess the quality of the different approximations.

  2. Improved inequalities for one-electron moments of r

    NASA Astrophysics Data System (ADS)

    Brownstein, K. R.

    1994-01-01

    Let =∫r kρr 2 dr be the kth moment of r for the one-electron radial density ρ(r). One obtains improved (Schwarz-like) inequalities for these moments if ρ is Nth-order monotonic, i.e., if dNρ/dr n is of one sign. These are of the form ≥GN(a,b), where GN(a,b) increases with N. In particular for (a,b)=(1,-1), one obtains G0=1 (Schwarz inequality), G1=9/8 (as obtained by Gadre), and G∞=3/2 in the limit N→∞. One also obtains similarly improved (Gram-like) determinantal inequalities for r moments in terms of the order of monotonicity N. Several examples using published r moments are presented.

  3. Oxidative injury in multiple sclerosis cerebellar grey matter.

    PubMed

    Kemp, Kevin; Redondo, Juliana; Hares, Kelly; Rice, Claire; Scolding, Neil; Wilkins, Alastair

    2016-07-01

    Cerebellar dysfunction is a significant contributor to disability in multiple sclerosis (MS). Both white matter (WM) and grey matter (GM) injury occurs within MS cerebellum and, within GM, demyelination, inflammatory cell infiltration and neuronal injury contribute to on-going pathology. The precise nature of cerebellar GM injury is, however, unknown. Oxidative stress pathways with ultimate lipid peroxidation and cell membrane injury occur extensively in MS and the purpose of this study was to investigate these processes in MS cerebellar GM. Post-mortem human cerebellar GM from MS and control subjects was analysed immunohistochemically, followed by semi-quantitative analysis of markers of cellular injury, lipid peroxidation and anti-oxidant enzyme expression. We have shown evidence for reduction in myelin and neuronal markers in MS GM, coupled to an increase in expression of a microglial marker. We also show that the lipid peroxidation product 4-hydroxynonenal co-localises with myelin and its levels negatively correlate to myelin basic protein levels. Furthermore, superoxide dismutase (SOD1 and 2) enzymes, localised within cerebellar neurons, are up-regulated, yet the activation of subsequent enzymes responsible for the detoxification of hydrogen peroxide, catalase and glutathione peroxidase are relatively deficient. These studies provide evidence for oxidative injury in MS cerebellar GM and further help define disease mechanisms within the MS brain. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Simultaneous evaluation of one-electron reducing systems and radical reactions in cells by nitroxyl biradical as probe.

    PubMed

    Araki, Yoko; Koshiishi, Ichiro

    2016-07-01

    In the present study, a novel probe for the simultaneous evaluation of one-electron reducing systems (electron transport chain) and one-electron oxidizing systems (free radical reactions) in cells by electron chemical detection was developed. Six-membered cyclic nitroxyl radicals (2,2,6,6-tetramethylpiperidine-1-oxyl; TEMPO series) are sensitive to one-electron redox systems, generating the hydroxylamine form [TEMPO(H)] via one-electron reduction, and the secondary amine form [TEMPO(N)] via one-electron oxidation in the presence of thiols. In contrast, the sensitivities of five-membered cyclic nitroxyl radicals (2,2,5,5-tetramethylpyrrolidine-1-oxyl; PROXYL series) to the one-electron redox systems are comparatively low. The electron chemical detector can detect 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), TEMPO(H) and PROXYL but not TEMPO(N). Therefore, nitroxyl biradical, TEMPO-PROXYL, as a probe for the evaluation of one-electron redox systems was employed. TEMPO-PROXYL was synthesized by the conjunction of 4-amino-TEMPO with 3-carboxyl-PROXYL via the conventional dicyclohexyl carbodiimide reaction. TEMPO-PROXYL, TEMPO(H)-PROXYL and TEMPO(N)-PROXYL were simultaneously quantified by HPLC with Coularray detection. Calibration curves for the quantification of TEMPO-PROXYL, TEMPO(H)-PROXYL and TEMPO(N)-PROXYL were linear in the range from 80 nm to 80 μm, and the lowest quantification limit of each molecule was estimated to be <80 nm. The relative standard deviations at 0.8 and 80 μm were within 10% (n = 5). Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Molecular structural formulas as one-electron density and hamiltonian operators: the VIF method extended.

    PubMed

    Alia, Joseph D

    2007-03-29

    The valency interaction formula (VIF) method is given a broader and more general interpretation in which these simple molecular structural formulas implicitly include all overlaps between valence atomic orbitals even for interactions not drawn in the VIF picture. This applies for VIF pictures as one-electron Hamiltonian operators as well as VIF pictures as one-electron density operators that constitute a new implementation of the VIF method simpler in its application and more accurate in its results than previous approaches. A procedure for estimating elements of the effective charge density-bond order matrix, Pmunu, from electron configurations in atoms is presented, and it is shown how these lead to loop and line constants in the VIF picture. From these structural formulas, one finds the number of singly, doubly, and unoccupied molecular orbitals, as well as the number of molecular orbitals with energy lower, equal, and higher than -1/2Eh, the negative of the hydrogen atom's ionization energy. The VIF results for water are in qualitative agreement with MP2/6311++G3df3pd, MO energy levels where the simple VIF for water presented in the earlier literature does not agree with computed energy levels. The method presented here gives the simplest accurate VIF pictures for hydrocarbons. It is shown how VIF can be used to predict thermal barriers to chemical reactions. Insertion of singlet carbene into H2 is given as an example. VIF pictures as one-electron density operators describe the ground-state multiplicities of B2, N2, and O2 molecules and as one-electron Hamiltonian operators give the correct electronegativity trend across period two. Previous implementations of VIF do not indicate singly occupied molecular orbitals directly from the pictorial VIF rules for these examples. The direct comparison between structural formulas that represent electron density and those that represent energy is supported by comparison of a simple electronegativity scale, chiD=N/n2, with

  6. Analysis of active neutron multiplicity data for Y-12 skull oxide samples

    SciTech Connect

    Krick, M.S.; Ensslin, N.; Ceo, R.N.; May, P.K.

    1996-09-01

    Previous work on active neutron multiplicity measurements and analyses is summarized. New active multiplicity measurements are described for samples of Y-12 skull oxide using an Active Well Coincidence Counter and MSR4 multiplicity electronics. Neutron multiplication values for the samples were determined from triples/doubles ratios. Neutron multiplication values were also obtained from Monte Carlo calculations using the MCNP code and the results compared with the experimental values. A calibration curve of AmLi source-sample coupling vs neutron multiplication was determined and used for active multiplicity assay of the skull oxides. The results are compared with those obtained from assay with the conventional calibration-curve technique, where the doubles rate is calibrated vs the {sup 235}U mass. The coupling-multiplication relationship determined for the skull oxides is compared with that determined earlier for pure high-enrichment uranium metal and pure uranium oxide. Conclusions are drawn about the application of active multiplicity techniques to uranium assay. Additional active multiplicity measurements and calculations are recommended.

  7. Oxidative Stress is Increased in Serum from Mexican Patients with Relapsing-Remitting Multiple Sclerosis

    PubMed Central

    Ortiz, Genaro Gabriel; Macías-Islas, Miguel Ángel; Pacheco-Moisés, Fermín P.; Cruz-Ramos, José A.; Sustersik, Silvia; Barba, Elías Alejandro; Aguayo, Adriana

    2009-01-01

    Objective: To determine the oxidative stress markers in serum from patients with relapsing-remitting multiple sclerosis. Methods: Blood samples from healthy controls and 22 patients 15 women (7 aged from 20 to 30 and 8 were > 40 years old) and 7 men (5 aged from 20 to 30 and 2 were > 40 years old) fulfilling the McDonald Criteria and classified as having Relapsing-Remitting Multiple Sclerosis accordingly with Lublin were collected for oxidative stress markers quantification. Results: Nitric oxide metabolites (nitrates/nitrites), lipid peroxidation products (malondialdehyde plus 4-hidroxialkenals), and glutathione peroxidase activity were significantly increased in serum of subjects with relapsing-remitting multiple sclerosis in comparison with that of healthy controls. These data support the hypothesis that multiple sclerosis is a component closely linked to oxidative stress. PMID:19242067

  8. Poorly soluble cobalt oxide particles trigger genotoxicity via multiple pathways.

    PubMed

    Uboldi, Chiara; Orsière, Thierry; Darolles, Carine; Aloin, Valérie; Tassistro, Virginie; George, Isabelle; Malard, Véronique

    2016-02-03

    Poorly soluble cobalt (II, III) oxide particles (Co3O4P) are believed to induce in vitro cytotoxic effects via a Trojan-horse mechanism. Once internalized into lysosomal and acidic intracellular compartments, Co3O4P slowly release a low amount of cobalt ions (Co(2+)) that impair the viability of in vitro cultures. In this study, we focused on the genotoxic potential of Co3O4P by performing a comprehensive investigation of the DNA damage exerted in BEAS-2B human bronchial epithelial cells. Our results demonstrate that poorly soluble Co3O4P enhanced the formation of micronuclei in binucleated cells. Moreover, by comet assay we showed that Co3O4P induced primary and oxidative DNA damage, and by scoring the formation of γ-H2Ax foci, we demonstrated that Co3O4P also generated double DNA strand breaks. By comparing the effects exerted by poorly soluble Co3O4P with those obtained in the presence of soluble cobalt chloride (CoCl2), we demonstrated that the genotoxic effects of Co3O4P are not simply due to the released Co(2+) but are induced by the particles themselves, as genotoxicity is observed at very low Co3O4P concentrations.

  9. Status of oxidant, antioxidantand serum enzymes in thalassaemic children receiving multiple blood transfusions.

    PubMed

    Asif, Mahmood; Manzoor, Zahid; Farooq, Muhammad Shehzad; Munawar, Shaukat Hussain; Aziz, Abdul; Khan, Imran Ahmad

    2015-08-01

    To determine the levels of oxidant, antioxidant and serum enzymes in thalassaemic children receiving multiple blood transfusions. The case-control study was done from February to August 2012, and comprised thalassaemic children receiving multiple blood transfusions at Allied Hospital, Ali Zeb Foundation, and the Thalassaemia Centre in Hilal-e-Ahmar Hospital, Faisalabad, Pakistan. Healthy subjects were also screened for any related disease condition that could prejudice the results. Blood samples were analysed for the values of total oxidant status, total antioxidant capacity, serum malondialdehyde, catalase, paraoxonase, arylesterase, glutathione peroxidase and ceruloplasmin. There were 180 children in the study; 90(50%) cases and 90(50%) controls. Of the cases, 48(53.3%) were under-weight while the weight of 42(46.7%) was in the normal range. The values of total oxidant status and total antioxidant capacity were significantly (p<0.01) higher in thalassaemic children compared to normal values. Serum malondialdehyde and catalase levels were also considerably elevated (p<0.05), suggesting the increased activity of these enzymes. However, the concentrations of serum paraoxonase, arylesterase, glutathione peroxidase were significantly (p<0.01) lower in cases than the controls, displaying diminished activities during multiple blood transfusions in these patients. Multiple blood transfusions disconcert the levels of oxidants, antioxidants and serum enzymes of thalassaemic children. Oxidative damage is seen because of the increased iron overload in these patients. Hence, regular evaluation of oxidant and antioxidant status should be monitored in thalassaemic patients during initial few years of life.

  10. Pulsed ELDOR spectroscopy of the Mo(V)/Fe(III) state of sulfite oxidase prepared by one-electron reduction with Ti(III) citrate.

    PubMed

    Codd, Rachel; Astashkin, Andrei V; Pacheco, Andrew; Raitsimring, Arnold M; Enemark, John H

    2002-03-01

    The titration of chicken liver sulfite oxidase (SO) with the one-electron reductant Ti(III) citrate, at pH 7.0, results in nearly quantitative selective reduction of the Mo(VI) center to Mo(V), while the b-type heme center remains in the fully oxidized Fe(III) state. The selective reduction of the Mo(VI/V) couple has been established from electronic and EPR spectra. The electronic spectrum of the Fe(III) heme center is essentially unchanged during the titration, and the continuous wave (CW)-EPR spectrum shows the appearance of the well-known Mo(V) signal due to the low pH ( lpH) form of SO. Further confirmation of the selective formation of the Mo(V)/Fe(III) form of SO is provided by the approximately 1:1 ratio of the integrated intensities of the Mo(V) and low-spin Fe(III) EPR signals after addition of one equivalent of Ti(III). The selective generation of the Mo(V)/Fe(III) form of SO is unexpected, considering that previous microcoulometry and flash photolysis investigations have indicated that the Mo(VI/V) and Fe(III/II) couples of SO have similar reduction potentials at pH 7. The nearly quantitative preparation of the one-electron reduced Mo(V)/Fe(III) form of SO by reduction with Ti(III) has enabled the interaction between these two paramagnetic metal centers, which are linked by a flexible loop with no secondary structure, to be investigated for the first time by variable-frequency pulsed electron-electron double resonance (ELDOR) spectroscopy. The ELDOR kinetics were obtained from frozen solutions at 4.2 K at several microwave frequencies by pumping on the narrow Mo(V) signal and observing the effect on the Fe(III) primary echo at both higher and lower frequencies within the microwave C-band region. The ELDOR data indicate that freezing the solution of one-electron reduced SO produces localized regions where the concentration of SO approaches that in the crystal structure, which results in the interpair interactions being the dominant dipolar interaction

  11. Multiple nanostructures based on anodized aluminium oxide templates

    NASA Astrophysics Data System (ADS)

    Wen, Liaoyong; Xu, Rui; Mi, Yan; Lei, Yong

    2016-11-01

    Several physico-chemical effects and properties in the solid state involve nanoscale interactions between adjacent materials and morphologies. Arrays of binary nanostructures can generate intimate interactions between different sub-components, but fabricating binary nanostructures is challenging. Here, we propose a concept to achieve diverse binary nanostructure arrays with high degrees of controllability for each of the sub-components, including material, dimension and morphology. This binary nanostructuring concept originates with a distinctive binary-pore anodized aluminium oxide template that includes two dissimilar sets of pores in one matrix, where the openings of the two sets of pores are towards opposite sides of the template. Using the same growth mechanism, the binary-pore template can be extended to multi-pore templates with more geometrical options. We also present photoelectrodes, transistors and plasmonic devices made with our binary nanostructure arrays using different combination of materials and morphologies, and demonstrate superior performances compared to their single-component counterparts.

  12. Achieving accurate nuetron-multiplicity analysis of metals and oxides with weighted point model equations.

    SciTech Connect

    Burward-Hoy, J. M.; Geist, W. H.; Krick, M. S.; Mayo, D. R.

    2004-01-01

    Neutron multiplicity counting is a technique for the rapid, nondestructive measurement of plutonium mass in pure and impure materials. This technique is very powerful because it uses the measured coincidence count rates to determine the sample mass without requiring a set of representative standards for calibration. Interpreting measured singles, doubles, and triples count rates using the three-parameter standard point model accurately determines plutonium mass, neutron multiplication, and the ratio of ({alpha},n) to spontaneous-fission neutrons (alpha) for oxides of moderate mass. However, underlying standard point model assumptions - including constant neutron energy and constant multiplication throughout the sample - cause significant biases for the mass, multiplication, and alpha in measurements of metal and large, dense oxides.

  13. Hydroxycitric acid ameliorates inflammation and oxidative stress in mouse models of multiple sclerosis

    PubMed Central

    Goudarzvand, Mahdi; Afraei, Sanaz; Yaslianifard, Somaye; Ghiasy, Saleh; Sadri, Ghazal; Kalvandi, Mustafa; Alinia, Tina; Mohebbi, Ali; Yazdani, Reza; Azarian, Shahin Khadem; Mirshafiey, Abbas; Azizi, Gholamreza

    2016-01-01

    Hydroxycitric acid (HCA) is derived primarily from the Garcinia plant and is widely used for its anti-inflammatory effects. Multiple sclerosis can cause an inflammatory demyelination and axonal damage. In this study, to validate the hypothesis that HCA exhibits therapeutic effects on multiple sclerosis, we established female C57BL/6 mouse models of multiple sclerosis, i.e., experimental autoimmune encephalomyelitis, using Complete Freund's Adjuvant (CFA) emulsion containing myelin oligodendrocyte glycoprotein (35–55). Treatment with HCA at 2 g/kg/d for 3 weeks obviously improved the symptoms of nerve injury of experimental autoimmune encephalomyelitis mice, decreased serum interleulin-6, tumor necrosis factor alpha, nitric oxide, and malondialdehyde levels, and increased superoxide dismutase and glutathione reductase activities. These findings suggest that HCA exhibits neuroprotective effects on multiple sclerosis-caused nerve injury through ameliorating inflammation and oxidative stress. PMID:27904492

  14. Multiple Hits, Including Oxidative Stress, as Pathogenesis and Treatment Target in Non-Alcoholic Steatohepatitis (NASH)

    PubMed Central

    Takaki, Akinobu; Kawai, Daisuke; Yamamoto, Kazuhide

    2013-01-01

    Multiple parallel hits, including genetic differences, insulin resistance and intestinal microbiota, account for the progression of non-alcoholic steatohepatitis (NASH). Multiple hits induce adipokine secretion, endoplasmic reticulum (ER) and oxidative stress at the cellular level that subsequently induce hepatic steatosis, inflammation and fibrosis, among which oxidative stress is considered a key contributor to progression from simple fatty liver to NASH. Although several clinical trials have shown that anti-oxidative therapy can effectively control hepatitis activities in the short term, the long-term effect remains obscure. Several trials of long-term anti-oxidant protocols aimed at treating cerebrovascular diseases or cancer development have failed to produce a benefit. This might be explained by the non-selective anti-oxidative properties of these drugs. Molecular hydrogen is an effective antioxidant that reduces only cytotoxic reactive oxygen species (ROS) and several diseases associated with oxidative stress are sensitive to hydrogen. The progress of NASH to hepatocellular carcinoma can be controlled using hydrogen-rich water. Thus, targeting mitochondrial oxidative stress might be a good candidate for NASH treatment. Long term clinical intervention is needed to control this complex lifestyle-related disease. PMID:24132155

  15. Placental endothelial nitric oxide synthase in multiple and single dose betamethasone exposed pregnancies.

    PubMed

    Mertz, Heather L; Mele, Lisa; Spong, Catherine Y; Dudley, Donald J; Wapner, Ronald J; Iams, Jay D; Sorokin, Yoram; Peaceman, Alan; Leveno, Kenneth J; Caritis, Steve N; Miodovnik, Menachem; Mercer, Brian M; Thorp, John M; O'Sullivan, Mary J; Ramin, Susan M; Carpenter, Marshall; Rouse, Dwight J; Sibai, Baha

    2011-06-01

    To compare endothelial nitric oxide synthase expression and capillary density (CDS) in placentas exposed to single or multiple courses of betamethasone. Placental specimens exposed to single vs repeat courses of betamethasone were analyzed through immunohistochemistry and digital image quantification for endothelial nitric oxide synthase and CD34. Quantified endothelial nitric oxide synthase staining, calculated capillary density, ratio of endothelial nitric oxide synthase to capillary density, and clinical characteristics were compared. Linear regression was performed with these as dependent variables. Mean and maximum capillary density were increased (P = .013 and .005) and the ratio of endothelial nitric oxide synthase to capillary density decreased (P = .016) in specimens exposed to 4 courses of betamethasone compared with 1 to 3 courses. Exposure to 4 courses of betamethasone was associated with increased capillary density, but not with endothelial nitric oxide synthase expression. Exposure to 4 courses of betamethasone is associated with increased placental capillary density. The placental effects of multiple courses of betamethasone are unrelated to endothelial nitric oxide synthase expression. Copyright © 2011 Mosby, Inc. All rights reserved.

  16. Electrochemical and Spectroscopic Evidence on the One-Electron Reduction of U(VI) to U(V) on Magnetite

    SciTech Connect

    Yuan, Ke; Ilton, Eugene S.; Antonio, Mark R.; Li, Zhongrui; Cook, Peter J.; Becker, Udo

    2015-05-19

    Reduction of U(VI) to U(VI) on mineral surfaces is often considered a one-step two-electron process. However, stabilized U(V), with no evidence of U(IV), found in recent studies Indicates U(VI) can undergo a one-electron reduction to U(V) without further progression to U(VI),. We investigated reduction pathways of uranium by reducing U(VI) electrochemically on a, magnetite electrode at,pH 3.4. Cyclic voltammetry confirms the one-electron reduction of U(VI) . Formation of nanosize uranium precipitates on the magnetite surface at reducing potentials and dissolution of the solids at oxidizing potentials are observed by in situ electrochemical atomic force microscopy. XPS, analysis Of the magnetite electrodes polarized in uranium solutions at voltages - from -0.1 to -0.9 V (E-U(VI)/U(V)(0)= -0.135 V vs Ag/AgCl) show the presence of, only U(V) and U(VI). The sample with the highest U(V)/U(VI) ratio was prepared at -0.7 V, where the longest average U-O-axial distance of 2.05 + 0.01 A was evident in the same sample revealed by extended X-ray absorption fine structure analysis. The results demonstrate that the electrochemical reduction of U(VI) On magnetite only yields,U(V), even at a potential of -0.9 V, which favors the one-electron reduction mechanism, U(V) does not disproportionate but stabilizes on magnetite through precipitation Of mixed-valence state -U(V)/U(VI) solids.

  17. Electrochemical and spectroscopic evidence on the one-electron reduction of U(VI) to U(V) on magnetite

    SciTech Connect

    Yuan, Ke; Ilton, Eugene S.; Antonio, Mark R.; Li, Zhongrui; Cook, Peter J.; Becker, Udo

    2015-05-19

    Reduction of U(VI) to U(IV) on mineral surfaces has been considered as a one-step two electron process. However, stabilized U(V), with no evidence of U(IV), found in recent studies indicates U(VI) can undergo a one electron reduction to U(V) without further progression to U(IV). We investigated the mechanisms of uranium reduction by reducing U(VI) electrochemically on a magnetite electrode at pH 3.4 . The one electron reduction of U(VI) was first confirmed using the cyclic voltammetry method. Formation of nano-size uranium precipitates on the surface of magnetite at reducing potentials and dissolution of the solids at oxidizing potentials were observed by in situ electrochemical AFM. XPS analysis of the magnetite electrodes polarized in uranium solutions at voltages from 0.1 ~ 0.9 V (vs. Ag/AgCl) showed the presence of only U(V) and U(VI). The highest amount of U(V) relative to U(VI) was prepared at 0.7 V, where the longest average U–Oaxial distance of 2.05 ± 0.01 Å was evident in the same sample revealed by EXAFS analysis. The results demonstrate that the electrochemical reduction of U(VI) on magnetite only yields U(V), even at a potential of 0.9 V, which favors the one-electron reduction mechanism. U(V) did not disproportionate but stabilized on magnetite through precipitation of mixed-valence state U(VI)/U(V) solids.

  18. Electrochemical and Spectroscopic Evidence on the One-Electron Reduction of U(VI) to U(V) on Magnetite.

    PubMed

    Yuan, Ke; Ilton, Eugene S; Antonio, Mark R; Li, Zhongrui; Cook, Peter J; Becker, Udo

    2015-05-19

    Reduction of U(VI) to U(IV) on mineral surfaces is often considered a one-step two-electron process. However, stabilized U(V), with no evidence of U(IV), found in recent studies indicates U(VI) can undergo a one-electron reduction to U(V) without further progression to U(IV). We investigated reduction pathways of uranium by reducing U(VI) electrochemically on a magnetite electrode at pH 3.4. Cyclic voltammetry confirms the one-electron reduction of U(VI) to U(V). Formation of nanosize uranium precipitates on the magnetite surface at reducing potentials and dissolution of the solids at oxidizing potentials are observed by in situ electrochemical atomic force microscopy. XPS analysis of the magnetite electrodes polarized in uranium solutions at voltages from -0.1 to -0.9 V (E(0)(U(VI)/U(V))= -0.135 V vs Ag/AgCl) show the presence of only U(V) and U(VI). The sample with the highest U(V)/U(VI) ratio was prepared at -0.7 V, where the longest average U-O(axial) distance of 2.05 ± 0.01 Å was evident in the same sample revealed by extended X-ray absorption fine structure analysis. The results demonstrate that the electrochemical reduction of U(VI) on magnetite only yields U(V), even at a potential of -0.9 V, which favors the one-electron reduction mechanism. U(V) does not disproportionate but stabilizes on magnetite through precipitation of mixed-valence state U(V)/U(VI) solids.

  19. Multiple transport systems mediate virus-induced acquired resistance to oxidative stress

    USDA-ARS?s Scientific Manuscript database

    In this paper, we report the phenomenon of acquired cross-tolerance to oxidative (UV-C and H2O2) stress in Nicotiana benthamiana plants infected with Potato virus X (PVX) and investigate the functional expression of transport systems in mediating this phenomenon. By combining multiple approaches, we...

  20. Integration of graphene oxide and DNA as a universal platform for multiple arithmetic logic units.

    PubMed

    Wang, Kun; Ren, Jiangtao; Fan, Daoqing; Liu, Yaqing; Wang, Erkang

    2014-11-28

    By a combination of graphene oxide and DNA, a universal platform was developed for integration of multiple logic gates to implement both half adder and half subtractor functions. A constant undefined threshold range between high and low fluorescence output signals was set for all the developed logic gates.

  1. One-electron singular spectral features of the 1D Hubbard model at finite magnetic field

    NASA Astrophysics Data System (ADS)

    Carmelo, J. M. P.; Čadež, T.

    2017-01-01

    The momentum, electronic density, spin density, and interaction dependences of the exponents that control the (k , ω)-plane singular features of the σ = ↑ , ↓ one-electron spectral functions of the 1D Hubbard model at finite magnetic field are studied. The usual half-filling concepts of one-electron lower Hubbard band and upper Hubbard band are defined in terms of the rotated electrons associated with the model Bethe-ansatz solution for all electronic density and spin density values and the whole finite repulsion range. Such rotated electrons are the link of the non-perturbative relation between the electrons and the pseudofermions. Our results further clarify the microscopic processes through which the pseudofermion dynamical theory accounts for the one-electron matrix elements between the ground state and excited energy eigenstates.

  2. Physicochemical Property and Oxidative Stability of Whey Protein Concentrate Multiple Nanoemulsion Containing Fish Oil.

    PubMed

    Hwang, Jae-Young; Ha, Ho-Kyung; Lee, Mee-Ryung; Kim, Jin Wook; Kim, Hyun-Jin; Lee, Won-Jae

    2017-02-01

    The objectives of this research were to produce whey protein concentrate (WPC) multiple nanoemulsion (MNE) and to study how whey protein concentration level and antioxidant type affected the physicochemical properties and oxidative stability of fish oil in MNE. The morphological and physicochemical characteristics of MNE were investigated by using transmission electron microscopy and particle size analyzer, respectively. The oxidative stability of fish oil in MNEs was assessed by measuring peroxide value (PV), p-anisidine value, and volatile compounds. The spherical forms of emulsions with size ranging from 190 to 210 nm were observed indicating the successful production of MNE. Compared with free fish oil, fish oil in MNE exhibited lower PV, p-anisidine value, and formation of maker of oxidation of fish oil indicating the oxidative stability of fish oil in MNE was enhanced. PV, p-anisidine value, and makers of oxidation of fish oil were decreased with increased WPC concentration level. The combined use of Vitamin C and E in MNE resulted in a reduction in PV and p-anisidine value, and development of maker of oxidation. In conclusion, WPC concentration level and antioxidant type are key factors affecting the droplet size of MNE and oxidative stability of fish oil. © 2017 Institute of Food Technologists®.

  3. One-electron standard reduction potentials of nitroaromatic and cyclic nitramine explosives

    USDA-ARS?s Scientific Manuscript database

    Extensive studies have been conducted in the past decades to predict the environmental abiotic and biotic redox fate of nitroaromatic and nitramine explosives. However, surprisingly little information is available on one-electron standard reduction potentials (Eo(R-NO2/R-NO2_)). The Eo(R-NO2/R-NO2...

  4. Redox equilibration after one-electron reduction of cytochrome c oxidase: radical formation and a possible hydrogen relay mechanism.

    PubMed

    Ashe, Damian; Alleyne, Trevor; Wilson, Michael; Svistunenko, Dimitri; Nicholls, Peter

    2014-07-15

    Kinetic studies using UV/visible and EPR spectroscopy were carried out to follow the distribution of electrons within beef heart cytochrome c oxidase (CcO), both active and cyanide-inhibited, following addition of reduced cytochrome c as electron donor. In the initial one-electron reduced state the electron is shared between three redox centers, heme a, CuA and a third site, probably CuB. Using a rapid freeze system and the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) a protein radical was also detected. The EPR spectrum of the DMPO adduct of this radical was consistent with tyrosyl radical capture. This may be a feature of a charge relay mechanism involved in some part of the CcO electron transfer system from bound cytochrome c via CuA and heme a to the a3CuB binuclear center. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Superparamagnetic Iron Oxide Nanoparticles: Promises for Diagnosis and Treatment of Multiple Sclerosis

    PubMed Central

    2011-01-01

    Smart superparamagnetic iron oxide nanoparticles (SPIONs) are the most promising candidate for theragnosis (i.e., diagnosis and treatment) of multiple sclerosis. A deep understanding of the dynamics of the in vivo neuropathology of multiple sclerosis can be achieved by improving the efficiency of various medical techniques (e.g., positron emission tomography and magnetic resonance imaging) using multimodal SPIONs. In this Review, recent advances and challenges in the development of smart SPIONs for theragnostic applications are comprehensively described. In addition, critical outlines of emerging developments are provided from the points of view of both clinicians and nanotechnologists. PMID:22778862

  6. A one-electron approximation to domain-averaged Fermi hole analysis.

    PubMed

    Cooper, David L; Ponec, Robert

    2008-03-07

    In general, full domain-averaged Fermi hole (DAFH) analysis for correlated wavefunctions requires explicit use of the correlated pair density, but such a quantity is not always readily available. We propose instead a simple one-electron approximation, which we call pseudo-DAFH or pDAFH, and which requires instead only the natural orbitals (and their occupation numbers). From comparisons of the DAFH and pDAFH modes of analysis for the bond dissociation processes in H2, N2 and LiH, as well as for the electronic structure of more complex bonding patterns, such as in CH2Li2 and Li4, we conclude that pDAFH analysis could indeed prove to be very useful when the correlated pair density is not available. Detailed comparisons are also presented of values of the shared-electron distribution index (SEDI), a proposed one-electron approximation to it (pSEDI) and a generalized Wiberg index.

  7. Inflammation, Iron, Energy Failure, and Oxidative Stress in the Pathogenesis of Multiple Sclerosis

    PubMed Central

    Haider, Lukas

    2015-01-01

    Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system. Different trigger pathologies have been suggested by the primary cytodegenerative “inside-out” and primary inflammation-driven “outside-in” hypotheses. Recent data indicate that mitochondrial injury and subsequent energy failure are key factors in the induction of demyelination and neurodegeneration. The brain weighs only a few percent of the body mass but accounts for approximately 20% of the total basal oxygen consumption of mitochondria. Oxidative stress induces mitochondrial injury in patients with multiple sclerosis and energy failure in the central nervous system of susceptible individuals. The interconnected mechanisms responsible for free radical production in patients with multiple sclerosis are as follows: (i) inflammation-induced production of free radicals by activated immune cells, (ii) liberation of iron from the myelin sheets during demyelination, and (iii) mitochondrial injury and thus energy failure-related free radical production. In the present review, the different sources of oxidative stress and their relationships to patients with multiple sclerosis considering tissue injury mechanisms and clinical aspects have been discussed. PMID:26106458

  8. Role of dimethyl fumarate in oxidative stress of multiple sclerosis: A review.

    PubMed

    Suneetha, A; Raja Rajeswari, K

    2016-04-15

    Multiple sclerosis (MS) is a chronic inflammatory disease of the CNS affecting both white and grey matter. Inflammation and oxidative stress are also thought to promote tissue damage in multiple sclerosis. Recent data point at an important role of anti-oxidative pathways for tissue protection in chronic MS, particularly involving the transcription factor nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2). Thus, novel therapeutics enhancing cellular resistance to free radicals could prove useful for MS treatment. Oxidative stress and anti-oxidative pathways are important players in MS pathophysiology and constitute a promising target for future MS therapy with dimethyl fumarate. The clinical utility of DMF in multiple sclerosis is being explored through phase III trials with BG-12, which is an oral therapeutic agent. Currently a wide research is going on to find out the exact mechanism of DMF, till date it is not clear. Based on strong signals of nephrotoxicity in non-humans and the theoretical risk of renal cell cancer from intracellular accumulation of fumarate, post-marketing study of a large population of patients will be necessary to fully assess the long-term safety of dimethyl fumarate. The current treatment goals are to shorten the duration and severity of relapses, prolong the time between relapses, and delay progression of disability. In this regard, dimethyl fumarate offers a promising alternative to orally administered fingolimod (GILENYA) or teriflunomide (AUBAGIO), which are currently marketed in the United States under FDA-mandated Risk Evaluation and Mitigation Strategy (REMS) programs because of serious safety concerns. More clinical experience with all three agents will be necessary to differentiate the tolerability of long-term therapy for patients diagnosed with multiple sclerosis. This write-up provides the detailed information of dimethyl fumarate in treating the neuro disease, multiple sclerosis and its mechanism involved via

  9. Serum chemical elements and oxidative status in Alzheimer's disease, Parkinson disease and multiple sclerosis.

    PubMed

    Alimonti, Alessandro; Ristori, Giovanni; Giubilei, Franco; Stazi, Maria Antonia; Pino, Anna; Visconti, Andrea; Brescianini, Sonia; Sepe Monti, Micaela; Forte, Giovanni; Stanzione, Paolo; Bocca, Beatrice; Bomboi, Giuseppe; D'Ippolito, Cristina; Annibali, Viviana; Salvetti, Marco; Sancesario, Giuseppe

    2007-05-01

    The role of some chemical elements in neurodegeneration was suggested by various authors. To obtain a profile of chemical elements and oxidative status in complex neurological diseases, an unbiased "omics" approach, i.e., quantification of 26 elements and oxidative stress parameters (serum oxidative status (SOS) and serum anti-oxidant capacity (SAC)), combined with multivariate statistical procedures (forward discriminant analysis, FDA) to analyse the vast amount of data, was applied to four groups of subjects (53 patients with Alzheimer's disease (AD), 71 with Parkinson disease (PD), 60 with multiple sclerosis (MS) and 124 healthy individuals). Descriptive statistics revealed numerous differences between each disease and healthy status. A concordant imbalance (reduction in Fe, Zn and SAC, and increase in SOS) was shared by AD, PD and MS. The FDA yielded three significant discriminant functions based on age, SOS, Ca, Fe, Si, Sn, V, Zn and Zr, and identified disease-specific profiles of element imbalances, thus showing the appropriateness of the "omics" approach. It may help assess the contribution of chemical elements and oxidative stress to disease causation and may provide complex predictors of disease evolution or treatment response.

  10. Melatonin improves outcomes of heatstroke in mice by reducing brain inflammation and oxidative damage and multiple organ dysfunction.

    PubMed

    Tian, Yu-Feng; Lin, Cheng-Hsien; Hsu, Shu-Fen; Lin, Mao-Tsun

    2013-01-01

    We report here that when untreated mice underwent heat stress, they displayed thermoregulatory deficit (e.g., animals display hypothermia during room temperature exposure), brain (or hypothalamic) inflammation, ischemia, oxidative damage, hypothalamic-pituitary-adrenal axis impairment (e.g., decreased plasma levels of both adrenocorticotrophic hormone and corticosterone during heat stress), multiple organ dysfunction or failure, and lethality. Melatonin therapy significantly reduced the thermoregulatory deficit, brain inflammation, ischemia, oxidative damage, hypothalamic-pituitary-adrenal axis impairment, multiple organ dysfunction, and lethality caused by heat stroke. Our data indicate that melatonin may improve outcomes of heat stroke by reducing brain inflammation, oxidative damage, and multiple organ dysfunction.

  11. Mechanisms of Oxidative Damage in Multiple Sclerosis and Neurodegenerative Diseases: Therapeutic Modulation via Fumaric Acid Esters

    PubMed Central

    Lee, De-Hyung; Gold, Ralf; Linker, Ralf A.

    2012-01-01

    Oxidative stress plays a crucial role in many neurodegenerative conditions such as Alzheimer’s disease, amyotrophic lateral sclerosis and Parkinson’s as well as Huntington’s disease. Inflammation and oxidative stress are also thought to promote tissue damage in multiple sclerosis (MS). Recent data point at an important role of anti-oxidative pathways for tissue protection in chronic-progressive MS, particularly involving the transcription factor nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2). Thus, novel therapeutics enhancing cellular resistance to free radicals could prove useful for MS treatment. Here, fumaric acid esters (FAE) are a new, orally available treatment option which had already been tested in phase II/III MS trials demonstrating beneficial effects on relapse rates and magnetic resonance imaging markers. In vitro, application of dimethylfumarate (DMF) leads to stabilization of Nrf2, activation of Nrf2-dependent transcriptional activity and abundant synthesis of detoxifying proteins. Furthermore, application of FAE involves direct modification of the inhibitor of Nrf2, Kelch-like ECH-associated protein 1. On cellular levels, the application of FAE enhances neuronal survival and protects astrocytes against oxidative stress. Increased levels of Nrf2 are detected in the central nervous system of DMF treated mice suffering from experimental autoimmune encephalomyelitis (EAE), an animal model of MS. In EAE, DMF ameliorates the disease course and improves preservation of myelin, axons and neurons. Finally, Nrf2 is also up-regulated in the spinal cord of autopsy specimens from untreated patients with MS, probably as part of a naturally occurring anti-oxidative response. In summary, oxidative stress and anti-oxidative pathways are important players in MS pathophysiology and constitute a promising target for future MS therapies like FAE. PMID:23109883

  12. Immunology and Oxidative Stress in Multiple Sclerosis: Clinical and Basic Approach

    PubMed Central

    Ortiz, Genaro G.; Pacheco-Moisés, Fermín P.; Bitzer-Quintero, Oscar K.; Ramírez-Anguiano, Ana C.; Flores-Alvarado, Luis J.; Ramírez-Ramírez, Viridiana; Macias-Islas, Miguel A.; Torres-Sánchez, Erandis D.

    2013-01-01

    Multiple sclerosis (MS) exhibits many of the hallmarks of an inflammatory autoimmune disorder including breakdown of the blood-brain barrier (BBB), the recruitment of lymphocytes, microglia, and macrophages to lesion sites, the presence of multiple lesions, generally being more pronounced in the brain stem and spinal cord, the predominantly perivascular location of lesions, the temporal maturation of lesions from inflammation through demyelination, to gliosis and partial remyelination, and the presence of immunoglobulin in the central nervous system and cerebrospinal fluid. Lymphocytes activated in the periphery infiltrate the central nervous system to trigger a local immune response that ultimately damages myelin and axons. Pro-inflammatory cytokines amplify the inflammatory cascade by compromising the BBB, recruiting immune cells from the periphery, and activating resident microglia. inflammation-associated oxidative burst in activated microglia and macrophages plays an important role in the demyelination and free radical-mediated tissue injury in the pathogenesis of MS. The inflammatory environment in demyelinating lesions leads to the generation of oxygen- and nitrogen-free radicals as well as proinflammatory cytokines which contribute to the development and progression of the disease. Inflammation can lead to oxidative stress and vice versa. Thus, oxidative stress and inflammation are involved in a self-perpetuating cycle. PMID:24174971

  13. Immunology and oxidative stress in multiple sclerosis: clinical and basic approach.

    PubMed

    Ortiz, Genaro G; Pacheco-Moisés, Fermín P; Bitzer-Quintero, Oscar K; Ramírez-Anguiano, Ana C; Flores-Alvarado, Luis J; Ramírez-Ramírez, Viridiana; Macias-Islas, Miguel A; Torres-Sánchez, Erandis D

    2013-01-01

    Multiple sclerosis (MS) exhibits many of the hallmarks of an inflammatory autoimmune disorder including breakdown of the blood-brain barrier (BBB), the recruitment of lymphocytes, microglia, and macrophages to lesion sites, the presence of multiple lesions, generally being more pronounced in the brain stem and spinal cord, the predominantly perivascular location of lesions, the temporal maturation of lesions from inflammation through demyelination, to gliosis and partial remyelination, and the presence of immunoglobulin in the central nervous system and cerebrospinal fluid. Lymphocytes activated in the periphery infiltrate the central nervous system to trigger a local immune response that ultimately damages myelin and axons. Pro-inflammatory cytokines amplify the inflammatory cascade by compromising the BBB, recruiting immune cells from the periphery, and activating resident microglia. inflammation-associated oxidative burst in activated microglia and macrophages plays an important role in the demyelination and free radical-mediated tissue injury in the pathogenesis of MS. The inflammatory environment in demyelinating lesions leads to the generation of oxygen- and nitrogen-free radicals as well as proinflammatory cytokines which contribute to the development and progression of the disease. Inflammation can lead to oxidative stress and vice versa. Thus, oxidative stress and inflammation are involved in a self-perpetuating cycle.

  14. Redox behaviour of nifuroxazide: generation of the one-electron reduction product.

    PubMed

    Squella, J A; Letelier, M E; Lindermeyer, L; Nuñez-Vergara, L J

    1996-01-05

    The electrochemical properties of nifuroxazide have been investigated in aqueous and aqueous-DMF mixed solvents. In aqueous media, a single, irreversible four-electron reduction occurs to give the hydroxylamine derivative. In mixed media, a reversible one-electron reduction to form a nitro radical anion takes place. Cyclic voltammetric studies show that the anion radical product is stable, although the nitro radical anion intermediate shows a tendency to undergo further chemical reactions. A comparison with the voltammetric behaviour of other nitrofurans such as nifurtimox, nitrofurazone and furazolidone is made. The electrochemically-obtained parameters are correlated with the in vivo studies of oxygen consumption on Trypanosoma cruzi cell suspensions.

  15. Arsenate stabilized Cu₂O nanoparticle catalyst for one-electron transfer reversible reaction.

    PubMed

    Sahoo, Ramkrishna; Dutta, Soumen; Pradhan, Mukul; Ray, Chaiti; Roy, Anindita; Pal, Tarasankar; Pal, Anjali

    2014-05-14

    The befitting capping capabilities of AsO4(3-) provide a stable Cu2O nanocatalyst from a galvanic reaction between a Cu(II) precursor salt and As(0) nanoparticles. This stable Cu2O hydrosol appears to be a suitable catalyst for the one-electron transfer reversible redox reaction between Eosin Y and NaBH4. The progress of the reaction relates to three different kinetic stages. In the presence of the new catalyst the reversible redox reaction of Eosin Y in air shows a periodic color change providing a new crowd-pleasing demonstration, i.e. a "clock reaction".

  16. Resistive switching behavior and multiple transmittance states in solution-processed tungsten oxide.

    PubMed

    Wu, Wei-Ting; Wu, Jih-Jen; Chen, Jen-Sue

    2011-07-01

    In this work, a tungsten oxide (WO(x)) film is prepared using a thiourea-assisted solution process. We demonstrate a device composed of fluorine doped tin oxide (FTO)-glass/WO(x)/electrolyte/indium-tin oxide (ITO)-glass stacking electrochromic (EC) structure and Al electrodes that are locally patterned and interposed between the WO(x) film and electrolyte, which form an Al(top electrode)/WO(x)/FTO(bottom electrode) resistance random access memory (RRAM) unit. According to transmission electron microscopy and X-ray photoelectron spectroscopy analyses, the WO(x) film contains nanosize pores and metallic-tungsten nanoclusters which are scattered within the tungsten oxide layer and concentrated along the interface between the Al electrode and WO(x) film. With application of voltage to the ITO electrode, multiple transmittance states are achieved for the EC unit due to the different quantity of intercalated Li ions in the WO(x) film. As for the Al/WO(x)/FTO RRAM unit, a bipolar nonvolatile resistive switching behavior is attained by applying voltage on the Al top electrode, showing electrical bistability with an ON/OFF current ratio up to 1 × 10(4).

  17. Lipopolysaccharide Binding Protein and Oxidative Stress in a Multiple Sclerosis Model.

    PubMed

    Escribano, Begoña M; Medina-Fernández, Francisco J; Aguilar-Luque, Macarena; Agüera, Eduardo; Feijoo, Montserrat; Garcia-Maceira, Fe I; Lillo, Rafael; Vieyra-Reyes, Patricia; Giraldo, Ana I; Luque, Evelio; Drucker-Colín, René; Túnez, Isaac

    2017-01-01

    Recent findings in experimental autoimmune encephalomyelitis (EAE) suggest that altering certain bacterial populations present in the gut may lead to a proinflammatory condition, that could result in the development of multiple sclerosis (MS). Also, Reactive Oxygen Species seem to be involved in the course of MS. In this study, it has been aimed to relate all these variables starting from an analysis of the lipopolysaccharide (LPS) and LPS-binding protein (LBP) with the determination of parameters related to oxidative stress in the blood, brain and spinal cord. For this purpose, samples obtained from EAE rats and relapsing-remitting (RRMS) MS patients were used. In addition, EAE rats were treated with Natalizumab, N-acetyl-cysteine and dimethyl fumarate. Natalizumab was also employed in RRMS. The results of this study revealed an improvement in the clinical symptoms of the EAE and MS with the treatments, as well as a reduction in the oxidative stress parameters and in LBP. Correlations between the clinical variables of the disease, i.e. oxidative damage and LBP, were established. Although the conclusions of this research are indeed relevant, further investigation would be necessary to establish the intrinsic mechanisms of the MS-oxidative stress-microbiota relationship.

  18. Global methane and nitrous oxide emissions from terrestrial ecosystems due to multiple environmental changes

    DOE PAGES

    Tian, Hanqin; Chen, Guangsheng; Lu, Chaoqun; ...

    2015-03-16

    Greenhouse gas (GHG)-induced climate change is among the most pressing sustainability challenges facing humanity today, posing serious risks for ecosystem health. Methane (CH4) and nitrous oxide (N2O) are the two most important GHGs after carbon dioxide (CO2), but their regional and global budgets are not well known. In this paper, we applied a process-based coupled biogeochemical model to concurrently estimate the magnitude and spatial and temporal patterns of CH4 and N2O fluxes as driven by multiple environmental changes, including climate variability, rising atmospheric CO2, increasing nitrogen deposition, tropospheric ozone pollution, land use change, and nitrogen fertilizer use.

  19. Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices

    DOE PAGES

    Hubertus J. J. van Dam

    2016-04-27

    Density functional theory is currently the most widely applied method in electronic structure theory. The Kohn-Sham method, based on a fictitious system of noninteracting particles, is the workhorse of the theory. The particular form of the Kohn-Sham wave function admits only idempotent one-electron density matrices whereas wave functions of correlated electrons in post-Hartree-Fock methods invariably have fractional occupation numbers. Here we show that by generalizing the orbital concept and introducing a suitable dot product as well as a probability density, a noninteracting system can be chosen that can represent the one-electron density matrix of any system, even one with fractionalmore » occupation numbers. This fictitious system ensures that the exact electron density is accessible within density functional theory. It can also serve as the basis for reduced density matrix functional theory. Moreover, to aid the analysis of the results the orbitals may be assigned energies from a mean-field Hamiltonian. This produces energy levels that are akin to Hartree-Fock orbital energies such that conventional analyses based on Koopmans' theorem are available. Lastly, this system is convenient in formalisms that depend on creation and annihilation operators as they are trivially applied to single-determinant wave functions.« less

  20. Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices

    NASA Astrophysics Data System (ADS)

    van Dam, Hubertus J. J.

    2016-05-01

    Density functional theory is currently the most widely applied method in electronic structure theory. The Kohn-Sham method, based on a fictitious system of noninteracting particles, is the workhorse of the theory. The particular form of the Kohn-Sham wave function admits only idempotent one-electron density matrices whereas wave functions of correlated electrons in post-Hartree-Fock methods invariably have fractional occupation numbers. Here we show that by generalizing the orbital concept and introducing a suitable dot product as well as a probability density, a noninteracting system can be chosen that can represent the one-electron density matrix of any system, even one with fractional occupation numbers. This fictitious system ensures that the exact electron density is accessible within density functional theory. It can also serve as the basis for reduced density matrix functional theory. Moreover, to aid the analysis of the results the orbitals may be assigned energies from a mean-field Hamiltonian. This produces energy levels that are akin to Hartree-Fock orbital energies such that conventional analyses based on Koopmans' theorem are available. Finally, this system is convenient in formalisms that depend on creation and annihilation operators as they are trivially applied to single-determinant wave functions.

  1. QED calculations in heavy many-electron atoms and one-electron quasi-molecules

    NASA Astrophysics Data System (ADS)

    Tupitsyn, I. I.; Safronova, M. S.; Kozlov, M. G.; Porsev, S. G.; Shabaev, V. M.

    2016-05-01

    Construction of simple one-electron approach to one-loop QED operator is an important task for the relativistic quantum theory of atoms and molecules. In this work we used two modifications of the model QED potential approach to calculations of the Lamb shift in many-electron atoms and one-electron quasi-molecules. The model potential is constructed as a sum of local and nonlocal (separable) potentials. The nonlocal part of the model potential was introduced to reproduce exactly the diagonal elements and also off-diagonal elements of the one-loop ab initio QED operator. The one-particle model QED operator was introduced in the Dirac-Fock and CI+MBPT relativistic calculations of the heavy and super-heavy atoms and in the calculations of the diatomic quasi-molecules. The comparison of the data obtained in different approaches to the one-loop QED operator is presented. Model QED potential is applied to calculate Lamb shift in the U91+- U92+ dimer. The results are compared with Ref..

  2. Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices

    SciTech Connect

    Hubertus J. J. van Dam

    2016-04-27

    Density functional theory is currently the most widely applied method in electronic structure theory. The Kohn-Sham method, based on a fictitious system of noninteracting particles, is the workhorse of the theory. The particular form of the Kohn-Sham wave function admits only idempotent one-electron density matrices whereas wave functions of correlated electrons in post-Hartree-Fock methods invariably have fractional occupation numbers. Here we show that by generalizing the orbital concept and introducing a suitable dot product as well as a probability density, a noninteracting system can be chosen that can represent the one-electron density matrix of any system, even one with fractional occupation numbers. This fictitious system ensures that the exact electron density is accessible within density functional theory. It can also serve as the basis for reduced density matrix functional theory. Moreover, to aid the analysis of the results the orbitals may be assigned energies from a mean-field Hamiltonian. This produces energy levels that are akin to Hartree-Fock orbital energies such that conventional analyses based on Koopmans' theorem are available. Lastly, this system is convenient in formalisms that depend on creation and annihilation operators as they are trivially applied to single-determinant wave functions.

  3. Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices

    SciTech Connect

    Hubertus J. J. van Dam

    2016-04-27

    Density functional theory is currently the most widely applied method in electronic structure theory. The Kohn-Sham method, based on a fictitious system of noninteracting particles, is the workhorse of the theory. The particular form of the Kohn-Sham wave function admits only idempotent one-electron density matrices whereas wave functions of correlated electrons in post-Hartree-Fock methods invariably have fractional occupation numbers. Here we show that by generalizing the orbital concept and introducing a suitable dot product as well as a probability density, a noninteracting system can be chosen that can represent the one-electron density matrix of any system, even one with fractional occupation numbers. This fictitious system ensures that the exact electron density is accessible within density functional theory. It can also serve as the basis for reduced density matrix functional theory. Moreover, to aid the analysis of the results the orbitals may be assigned energies from a mean-field Hamiltonian. This produces energy levels that are akin to Hartree-Fock orbital energies such that conventional analyses based on Koopmans' theorem are available. Lastly, this system is convenient in formalisms that depend on creation and annihilation operators as they are trivially applied to single-determinant wave functions.

  4. Multiple roles of photosynthetic and sunscreen pigments in cyanobacteria focusing on the oxidative stress.

    PubMed

    Wada, Naoki; Sakamoto, Toshio; Matsugo, Seiichi

    2013-05-30

    Cyanobacteria have two types of sunscreen pigments, scytonemin and mycosporine-like amino acids (MAAs). These secondary metabolites are thought to play multiple roles against several environmental stresses such as UV radiation and desiccation. Not only the large molar absorption coefficients of these sunscreen pigments, but also their antioxidative properties may be necessary for the protection of biological molecules against the oxidative damages induced by UV radiation. The antioxidant activity and vitrification property of these pigments are thought to be requisite for the desiccation and rehydration processes in anhydrobiotes. In this review, the multiple roles of photosynthetic pigments and sunscreen pigments on stress resistance, especially from the viewpoint of their structures, biosynthetic pathway, and in vitro studies of their antioxidant activity, will be discussed.

  5. Multiple mechanisms for inhibition of low density lipoprotein oxidation by novel cyclic nitrone spin traps.

    PubMed

    Thomas, C E; Ohlweiler, D F; Kalyanaraman, B

    1994-11-11

    spectrophotometric quantitation of associated Cu2+. The ability to bind Cu2+ was dependent upon the presence of the spirocyclohexyl ring. These data demonstrate that cyclic nitrones can inhibit LDL oxidation at exceedingly low concentrations by multiple mechanisms: 1) trapping of lipid-derived radicals, 2) trapping of apoprotein B-derived radicals, and 3) binding of Cu2+ ions. It is suggested that this new class of highly potent spin traps may be used as effective radical traps in free radical biology and medicine.

  6. One-electron reduction of 8-bromo-2-aminoadenosine in the aqueous phase: radiation chemical and DFT studies of the mechanism.

    PubMed

    Kaloudis, Panagiotis; D'Angelantonio, Mila; Guerra, Maurizio; Gimisis, Thanasis; Mulazzani, Quinto G; Chatgilialoglu, Chryssostomos

    2008-04-24

    Two tautomeric forms of one-electron oxidized 2-aminoadenosine (2AA) have been produced by reactions of hydrated electrons (e aq-) with 8-bromo-2-aminoadenosine (8-Br-2AA) at natural pH, whereas only one tautomer is formed by oxidation of 2AA. Tailored experiments by pulse radiolysis and time-dependent DFT (TD-B3LYP/6-311G**//B1B95/6-31+G**) calculations allowed the definition of the reaction mechanism in some detail. The electron adducts of 8-Br-2AA protonated at C8 eject Br- and produce the two short-lived tautomers (8 and 9). The first observable species decays by first-order kinetics to produce the second intermediate, which is also obtained by oxidation of 2AA by SO4*-. The rate of tautomerization (k taut = 4.5 x 104 s-1) is strongly accelerated by phosphate and is retarded in D2O (kinetic isotope effect 7). B1B95/6-31+G** calculations showed that the tautomerization is a water-assisted process. In acidic or basic solutions, the "instantaneous" formation of one-electron oxidized 2AA or its deprotonated forms has been produced by reactions of e aq- with 8-Br-2AA. gamma-Radiolysis of 8-Br-2AA in aqueous solutions followed by product studies led to the formation of 2AA as a single product.

  7. Multiple factors affect diversity and abundance of ammonia-oxidizing microorganisms in iron mine soil.

    PubMed

    Xing, Yi; Si, Yan-Xiao; Hong, Chen; Li, Yang

    2015-07-01

    Ammonia oxidation by microorganisms is a critical process in the nitrogen cycle. In this study, four soil samples collected from a desert zone in an iron-exploration area and others from farmland and planted forest soil in an iron mine surrounding area. We analyzed the abundance and diversity of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in iron-mining area near the Miyun reservoir using ammonia monooxygenase. A subunit gene (amoA) as molecular biomarker. Quantitative polymerase chain reaction was applied to explore the relationships between the abundance of AOA and AOB and soil physicochemical parameters. The results showed that AOA were more abundant than AOB and may play a more dominant role in the ammonia-oxidizing process in the whole region. PCR-denaturing gradient gel electrophoresis was used to analyze the structural changes of AOA and AOB. The results showed that AOB were much more diverse than AOA. Nitrosospira cluster three constitute the majority of AOB, and AOA were dominated by group 1.1b in the soil. Redundancy analysis was performed to explore the physicochemical parameters potentially important to AOA and AOB. Soil characteristics (i.e. water, ammonia, organic carbon, total nitrogen, available phosphorus, and soil type) were proposed to potentially contribute to the distributions of AOB, whereas Cd was also closely correlated to the distributions of AOB. The community of AOA correlated with ammonium and water contents. These results highlight the importance of multiple drivers in microbial niche formation as well as their affect on ammonia oxidizer composition, both which have significant consequences for ecosystem nitrogen functioning.

  8. Multiple phase transition and scaling law for poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer in aqueous solution.

    PubMed

    Liu, Sijun; Li, Lin

    2015-02-04

    The multiple phase transition and the scaling behavior of a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (Pluronic F127, PEO100-PPO65-PEO100) have been studied by micro-differential scanning calorimetry and rheology. The scaling behavior of the triblock copolymer was examined using the Winter-Chambon criterion to obtain the critical gel temperature Tgel and the scaling exponent n. n was found to decrease linearly with increasing copolymer concentration. A stable hard gel was formed, but the hard gel was transformed into a soft gel upon further heating. Increasing copolymer concentration led to the increase in the temperature of hard-soft gel transition, while the sol-gel transition temperature decreased with increasing copolymer concentration. A phase diagram has been determined, which is able to classify unimers, micelles, hard gel, and soft gel regions upon heating. In addition, the scaling relation of the plateau modulus Ge with copolymer concentration was also obtained as Ge ≈ c(3.0) for both soft gel and hard gel.

  9. A Tandem Catalyst with Multiple Metal Oxide Interfaces Produced by Atomic Layer Deposition.

    PubMed

    Ge, Huibin; Zhang, Bin; Gu, Xiaomin; Liang, Haojie; Yang, Huimin; Gao, Zhe; Wang, Jianguo; Qin, Yong

    2016-06-13

    Ideal heterogeneous tandem catalysts necessitate the rational design and integration of collaborative active sites. Herein, we report on the synthesis of a new tandem catalyst with multiple metal-oxide interfaces based on a tube-in-tube nanostructure using template-assisted atomic layer deposition, in which Ni nanoparticles are supported on the outer surface of the inner Al2 O3 nanotube (Ni/Al2 O3 interface) and Pt nanoparticles are attached to the inner surface of the outer TiO2 nanotube (Pt/TiO2 interface). The tandem catalyst shows remarkably high catalytic efficiency in nitrobenzene hydrogenation over Pt/TiO2 interface with hydrogen formed in situ by the decomposition of hydrazine hydrate over Ni/Al2 O3 interface. This can be ascribed to the synergy effect of the two interfaces and the confined nanospace favoring the instant transfer of intermediates. The tube-in-tube tandem catalyst with multiple metal-oxide interfaces represents a new concept for the design of highly efficient and multifunctional nanocatalysts.

  10. Oxidative metabolism is associated with physiological disorders in fruits stored under multiple environmental stresses.

    PubMed

    Lum, Geoffrey B; Shelp, Barry J; DeEll, Jennifer R; Bozzo, Gale G

    2016-04-01

    In combination with low temperature, controlled atmosphere storage and 1-methylcyclopropene (ethylene antagonist) application are used to delay senescence of many fruits and vegetables. Controlled atmosphere consists of low O2 and elevated CO2. When sub-optimal partial pressures are used, these practices represent multiple abiotic stresses that can promote the development of physiological disorders in pome fruit, including flesh browning and cavities, although there is some evidence for genetic differences in susceptibility. In the absence of surface disorders, fruit with flesh injuries are not easily distinguished from asymptomatic fruit until these are consumed. Oxidative stress metabolites tend to accumulate (e.g., γ-aminobutyrate) or rapidly decline (e.g., ascorbate and glutathione) in vegetative tissues exposed to hypoxic and/or elevated CO2 environments. Moreover, these phenomena can be associated with altered energy and redox status. Biochemical investigations of Arabidopsis and tomato plants with genetically-altered levels of enzymes associated with the γ-aminobutyrate shunt and the ascorbate-glutathione pathway indicate that these metabolic processes are functionally related and critical for dampening the oxidative burst in vegetative and fruit tissues, respectively. Here, we hypothesize that γ-aminobutyrate accumulation, as well energy and antioxidant depletion are associated with the development of physiological injury in pome fruit under multiple environmental stresses. An improved understanding of this relationship could assist in maintaining the quality of stored fruit. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  11. Brassinosteroid-6-oxidases from Arabidopsis and tomato catalyze multiple C-6 oxidations in brassinosteroid biosynthesis.

    PubMed

    Shimada, Y; Fujioka, S; Miyauchi, N; Kushiro, M; Takatsuto, S; Nomura, T; Yokota, T; Kamiya, Y; Bishop, G J; Yoshida, S

    2001-06-01

    Brassinosteroids (BRs) are steroidal plant hormones that are essential for growth and development. It has been proposed that BRs are synthesized via two parallel pathways, the early and late C-6 oxidation pathways according to the C-6 oxidation status. The tomato (Lycopersicon esculentum) Dwarf gene encodes a cytochrome P450 that has been shown to catalyze the C-6 oxidation of 6-deoxocastasterone to castasterone. We isolated an Arabidopsis ortholog (AtBR6ox gene) of the tomato Dwarf gene. The encoded polypeptide has characteristics of P450s and is classified into the CYP85 family. The AtBR6ox and tomato Dwarf gene were expressed in yeast and the ability of the transformed yeast cells to metabolize 6-deoxo-BRs was tested. Metabolites were analyzed by gas chromatography-mass spectrometry. Both enzymes catalyze multiple steps in BR biosynthesis: 6-deoxoteasterone to teasterone, 3-dehydro-6-deoxoteasterone to 3-dehydroteasterone, 6-deoxotyphasterol to typhasterol, and 6-deoxocastasterone to castasterone. Our results indicate that the AtBR6ox gene and the tomato Dwarf gene encode steroid-6-oxidases and that these enzymes have a broad substrate specificity. This suggests that the BR biosynthetic pathway consists of a metabolic grid rather than two separate parallel pathways.

  12. Brassinosteroid-6-Oxidases from Arabidopsis and Tomato Catalyze Multiple C-6 Oxidations in Brassinosteroid Biosynthesis1

    PubMed Central

    Shimada, Yukihisa; Fujioka, Shozo; Miyauchi, Narumasa; Kushiro, Masayo; Takatsuto, Suguru; Nomura, Takahito; Yokota, Takao; Kamiya, Yuji; Bishop, Gerard J.; Yoshida, Shigeo

    2001-01-01

    Brassinosteroids (BRs) are steroidal plant hormones that are essential for growth and development. It has been proposed that BRs are synthesized via two parallel pathways, the early and late C-6 oxidation pathways according to the C-6 oxidation status. The tomato (Lycopersicon esculentum) Dwarf gene encodes a cytochrome P450 that has been shown to catalyze the C-6 oxidation of 6-deoxocastasterone to castasterone. We isolated an Arabidopsis ortholog (AtBR6ox gene) of the tomato Dwarf gene. The encoded polypeptide has characteristics of P450s and is classified into the CYP85 family. The AtBR6ox and tomato Dwarf gene were expressed in yeast and the ability of the transformed yeast cells to metabolize 6-deoxo-BRs was tested. Metabolites were analyzed by gas chromatography-mass spectrometry. Both enzymes catalyze multiple steps in BR biosynthesis: 6-deoxoteasterone to teasterone, 3-dehydro-6-deoxoteasterone to 3-dehydroteasterone, 6-deoxotyphasterol to typhasterol, and 6-deoxocastasterone to castasterone. Our results indicate that the AtBR6ox gene and the tomato Dwarf gene encode steroid-6-oxidases and that these enzymes have a broad substrate specificity. This suggests that the BR biosynthetic pathway consists of a metabolic grid rather than two separate parallel pathways. PMID:11402205

  13. Oxidative modification of blood serum proteins in multiple sclerosis after interferon or mitoxantrone treatment.

    PubMed

    Sadowska-Bartosz, Izabela; Adamczyk-Sowa, Monika; Gajewska, Agnieszka; Bartosz, Grzegorz

    2014-01-15

    This study was aimed at (i) comparison of the usefulness of serum protein oxidation parameters for assessment of oxidative stress (OS) in multiple sclerosis (MS), and (ii) comparison of OS in MS patients subject to various therapies. Elevated glycophore level was noted in relapsing-remitting (RRMS) patients without treatment and patients treated with interferons β1a and β1b (10.33±3.27, 8.02±2.22 and 8.56±2.45 vs control 5.27±0.73 fluorescence units (FU)/mg protein). Advanced oxidation protein products (295±135 vs 83±65nmol/mg protein), carbonyl groups (3.68±1.44nmol/mg protein vs 2.03±0.23nmol/mg protein), kynurenine (7.71±0.1.67 vs 5.5±0.63 FU/mg protein) and N'-formylkynurenine (7.69±0.7 vs 4.97±0.59 FU/mg protein) levels were increased, while thioredoxin level was decreased in RRMS patients without treatment (5.03±2.18 vs 10.83±2.75ng/ml) with respect to control. The level of OS was higher in untreated RRMS patients and in SPMS patients treated with mitoxantrone than in patients treated with interferon.

  14. Multiple sample characterization of coals and other substances by controlled-atmosphere programmed temperature oxidation

    DOEpatents

    LaCount, Robert B.

    1993-01-01

    A furnace with two hot zones holds multiple analysis tubes. Each tube has a separable sample-packing section positioned in the first hot zone and a catalyst-packing section positioned in the second hot zone. A mass flow controller is connected to an inlet of each sample tube, and gas is supplied to the mass flow controller. Oxygen is supplied through a mass flow controller to each tube to either or both of an inlet of the first tube and an intermediate portion between the tube sections to intermingle with and oxidize the entrained gases evolved from the sample. Oxidation of those gases is completed in the catalyst in each second tube section. A thermocouple within a sample reduces furnace temperature when an exothermic condition is sensed within the sample. Oxidized gases flow from outlets of the tubes to individual gas cells. The cells are sequentially aligned with an infrared detector, which senses the composition and quantities of the gas components. Each elongated cell is tapered inward toward the center from cell windows at the ends. Volume is reduced from a conventional cell, while permitting maximum interaction of gas with the light beam. Reduced volume and angulation of the cell inlets provide rapid purgings of the cell, providing shorter cycles between detections. For coal and other high molecular weight samples, from 50% to 100% oxygen is introduced to the tubes.

  15. Zeeman energy and spin relaxation in a one-electron quantum dot.

    PubMed

    Hanson, R; Witkamp, B; Vandersypen, L M K; van Beveren, L H Willems; Elzerman, J M; Kouwenhoven, L P

    2003-11-07

    We have measured the relaxation time, T1, of the spin of a single electron confined in a semiconductor quantum dot (a proposed quantum bit). In a magnetic field, applied parallel to the two-dimensional electron gas in which the quantum dot is defined, Zeeman splitting of the orbital states is directly observed by measurements of electron transport through the dot. By applying short voltage pulses, we can populate the excited spin state with one electron and monitor relaxation of the spin. We find a lower bound on T1 of 50 micros at 7.5 T, only limited by our signal-to-noise ratio. A continuous measurement of the charge on the dot has no observable effect on the spin relaxation.

  16. Frequency-dependent polarizabilities and shielding factors for confined one-electron systems

    NASA Astrophysics Data System (ADS)

    Montgomery, H. E., Jr.; Pupyshev, Vladimir I.

    2017-01-01

    Frequency-dependent dipole polarizabilities and shielding factors are calculated for the ground state of spherically symmetric screened one-electron systems embedded in an impenetrable spherical cavity. Coulomb, Yukawa, Hulthén and exponential cosine-screened Coulomb potentials are considered. In contrast to free systems, Dirichlet boundary conditions introduce a contribution to the shielding factor that results from an integral over the surface of the confining boundary. This is a fundamental difference between free and confined systems and results in unexpected modifications to some of the classic relations for free systems. The methods derived also give a simple expression for the polarizability of the confined harmonic oscillator as an example of extending the methods of this work to potentials beyond the four studied.

  17. Multiple controls of oxidative metabolism in living tissues as studied by phosphorus magnetic resonance.

    PubMed Central

    Chance, B; Leigh, J S; Kent, J; McCully, K; Nioka, S; Clark, B J; Maris, J M; Graham, T

    1986-01-01

    Three types of metabolic control of oxidative metabolism are observed in the various tissues that have been studied by phosphorous magnetic resonance spectroscopy. The principal control of oxidative metabolism in skeletal muscle is by ADP (or Pi/phosphocreatine). This conclusion is based upon studies of arm muscles of humans during steady-state exercise. A work-cost (Vm vs. Pi/phosphocreatine) relationship follows a Michaelis-Menten rectangular hyperbola, where Km values from 0.5 to 0.6 and Vmax values from 50 to 200 (at nearly constant pH) are found in linearized plots of the equation V/Vmax = 1/(1 + 0.6 phosphocreatine/Pi) where V is work level (which is equal to the velocity of the enzymatic reaction) and Vmax is the maximal work capacity that is a measure of the enzyme activity (E) of oxidative metabolism. Adaptation to exercise enhances the slope of the work-cost relationship and causes large changes in Vmax or E. A second metabolic control may enhance the slope of the work-cost relationship but not Vmax. For example, the initiation of exercise can lead to an improved characteristic that can be explained by 2-fold increased substrate delivery, for example, increased oxygen delivery by microcirculatory control. Cardiac tissue of the adult dog affords an example of optimal endurance performance adaptation and exhibits the steepest work-cost relationship observed and is attributed to a coordinated control of substrate delivery that may involve Ca2+ and inorganic phosphate control of NADH; control of O2 delivery may also be involved. The calculated work-cost relationship is similar to that observed in the beagle heart. The theoretical curve illustrates that the liability of multiple controls is a sharp break point in metabolic control at the end of the multiple control range--a possible cause of instability of cardiac performance at high V/Vmax. PMID:3467315

  18. Excess electrons in methanol clusters: Beyond the one-electron picture

    NASA Astrophysics Data System (ADS)

    Pohl, Gábor; Mones, Letif; Turi, László

    2016-10-01

    We performed a series of comparative quantum chemical calculations on various size negatively charged methanol clusters, ("separators=" CH 3 OH ) n - . The clusters are examined in their optimized geometries (n = 2-4), and in geometries taken from mixed quantum-classical molecular dynamics simulations at finite temperature (n = 2-128). These latter structures model potential electron binding sites in methanol clusters and in bulk methanol. In particular, we compute the vertical detachment energy (VDE) of an excess electron from increasing size methanol cluster anions using quantum chemical computations at various levels of theory including a one-electron pseudopotential model, several density functional theory (DFT) based methods, MP2 and coupled-cluster CCSD(T) calculations. The results suggest that at least four methanol molecules are needed to bind an excess electron on a hydrogen bonded methanol chain in a dipole bound state. Larger methanol clusters are able to form stronger interactions with an excess electron. The two simulated excess electron binding motifs in methanol clusters, interior and surface states, correlate well with distinct, experimentally found VDE tendencies with size. Interior states in a solvent cavity are stabilized significantly stronger than electron states on cluster surfaces. Although we find that all the examined quantum chemistry methods more or less overestimate the strength of the experimental excess electron stabilization, MP2, LC-BLYP, and BHandHLYP methods with diffuse basis sets provide a significantly better estimate of the VDE than traditional DFT methods (BLYP, B3LYP, X3LYP, PBE0). A comparison to the better performing many electron methods indicates that the examined one-electron pseudopotential can be reasonably used in simulations for systems of larger size.

  19. Excess electrons in methanol clusters: Beyond the one-electron picture.

    PubMed

    Pohl, Gábor; Mones, Letif; Turi, László

    2016-10-28

    We performed a series of comparative quantum chemical calculations on various size negatively charged methanol clusters, CH3OHn(-). The clusters are examined in their optimized geometries (n = 2-4), and in geometries taken from mixed quantum-classical molecular dynamics simulations at finite temperature (n = 2-128). These latter structures model potential electron binding sites in methanol clusters and in bulk methanol. In particular, we compute the vertical detachment energy (VDE) of an excess electron from increasing size methanol cluster anions using quantum chemical computations at various levels of theory including a one-electron pseudopotential model, several density functional theory (DFT) based methods, MP2 and coupled-cluster CCSD(T) calculations. The results suggest that at least four methanol molecules are needed to bind an excess electron on a hydrogen bonded methanol chain in a dipole bound state. Larger methanol clusters are able to form stronger interactions with an excess electron. The two simulated excess electron binding motifs in methanol clusters, interior and surface states, correlate well with distinct, experimentally found VDE tendencies with size. Interior states in a solvent cavity are stabilized significantly stronger than electron states on cluster surfaces. Although we find that all the examined quantum chemistry methods more or less overestimate the strength of the experimental excess electron stabilization, MP2, LC-BLYP, and BHandHLYP methods with diffuse basis sets provide a significantly better estimate of the VDE than traditional DFT methods (BLYP, B3LYP, X3LYP, PBE0). A comparison to the better performing many electron methods indicates that the examined one-electron pseudopotential can be reasonably used in simulations for systems of larger size.

  20. Evaluation of oxidative and nitrosative stress in relapsing remitting multiple sclerosis: effect of corticosteroid therapy.

    PubMed

    Seven, Aru; Aslan, Mahmure; Incir, Said; Altıntaş, Ayşe

    2013-01-01

    This study is designed to evaluate the roles of oxidative and nitrosative stress in serum and cerebrospinal fluid (CSF) of relapsing remitting multiple sclerosis (RRMS) patients. Oxidative stress markers thiobarbituric acid reactive substances (TBARS), 8-epi-PGF2α, conjugated diene and nitrosative stress markers nitrotyrosine, nitrit-nitrate were analysed in serum and CSF of 20 newly diagnosed RRMS patients before and after methyl prednysolone (MP) therapy (1000 mg/day i.v., for 5 days) and in healthy control group.TBARS and conjugated diene were analysed spectrophotometrically, nitrite-nitrate fluorometrically, 8-epi-PGF2α and nitrotyrosine were measured by ELISA. Serum conjugated diene (p < 0.001) and 8-epi-PGF2α (p < 0.05) levels were significantly higher in RRMS patients before MP therapy with respect to control group. MP therapy caused a significant decrease only in 8-epi-PGF2α level (p < 0.05). Serum nitrotyrosine levels were significantly lower in RRMS patients both before (p < 0.001) and after (p < 0.001) MP therapy with respect to controls. Serum nitrite-nitrate levels were significantly lower (p < 0.05) in RRMS patients before therapy compared to controls. Nitrotyrosine and nitrite-nitrate levels in CSF of RRMS patients were significantly higher (p < 0.001) before therapy compared to normal pressure hydrocephalia control group. Our findings reveal increased oxidative stress in serum of RRMS patients and the benefical role of MP therapy in relieving oxidative stress.As to nitrosative stress, nitrotyrosine and nitrite-nitrate levels were increased in CSF and decreased in serum.

  1. Are One-Electron Bonds Any Different from Standard Two-Electron Covalent Bonds?

    PubMed

    Sousa, David Wilian Oliveira de; Nascimento, Marco Antonio Chaer

    2017-09-19

    The nature of the chemical bond is perhaps the central subject in theoretical chemistry. Our understanding of the behavior of molecules developed amazingly in the last century, mostly with the rise of quantum mechanics (QM) and QM-based theories such as valence bond theory and molecular orbital theory. Such theories are very successful in describing molecular properties, but they are not able to explain the origin of the chemical bond. This problem was first analyzed in the 1960s by Ruedenberg, who showed that covalent bonds are the direct result of quantum interference between one-electron states. The generality of this result and its quantification were made possible through the recent development of the generalized product function energy partitioning (GPF-EP) method by our group, which allows the partitioning of the electronic density and energy into their interference and quasi-classical (noninterference) contributions. Furthermore, with GPF wave functions these effects can be analyzed separately for each bond of a molecule. This interference energy analysis has been applied to a large variety of molecules, including diatomics and polyatomics, molecules with single, double, and triple bonds, molecules with different degrees of polarity, linear or branched molecules, cyclic or acyclic molecules, conjugated molecules, and aromatics, in order to verify the role played by quantum interference. In all cases the conclusion is exactly the same: for each bond in each of the molecules considered, the main contribution to its stability comes from the interference term. Two-center one-electron (2c1e) bonds are the simplest kind of chemical bonds. Yet they are often viewed as odd or unconventional cases of bonding. Are they any different from conventional (2c2e) bonds? If so, what differences can we expect in the nature of (2c1e) bonds relative to electron-pair bonds? In this Account, we extend the GPF-EP method to describe bonds involving N electrons in M orbitals (N < M

  2. Investigations of the oxidation capacities of polar atmospheres with multiple oxygen isotopes

    NASA Astrophysics Data System (ADS)

    McCabe, Justin R.

    This study provides new perspectives on the atmospheric chemistry in Polar Regions using multiple oxygen isotopes of nitrate and sulfate. Despite their remote locations, these unique environments play an important role in the present state of global climate and contain invaluable clues to observing past relationships between earth's atmosphere and surface temperature. With current temperatures and greenhouse gas concentrations rising rapidly as a result of human activities, continued investigation of the effects on polar environments will elucidate their relationship to the global climate system. Three studies are presented here to constrain the oxidation pathways of nitrogen and sulfur compounds in polar atmospheres. These findings provide a new means to observe current and past oxidation conditions of tropospheric and stratospheric polar atmospheres. Currently, two uncertain aspects of climate are the projected changes in tropospheric and stratospheric oxidation chemistry and the role of aerosols in cloud formation and the global radiation budget. Because the levels of oxidants in the atmosphere directly influence greenhouse gas concentrations and aerosol distribution, the following work presents results implicit to improving knowledge of the climate system. The results presented in this dissertation include measurements of oxygen isotopes (delta17O, delta18O, and Delta 17O) in nitrate and sulfate from South Pole, Antarctica and Alert, Canada, respectively. In addition, a photochemistry experiment was conducted to measure the effects of ultraviolet (UV) irradiation on oxygen isotopes of nitrate in water and ice. Chapter 2 compares oxygen isotopes in sulfate aerosol collected at Alert, Canada over the course of one year (July 1999--June 2000) to a chemical transport model describing sulfate formation. Chapter 3 presents the results from the nitrate photochemistry experiments conducted at California Institute of Technology in Pasadena, California. Chapter 4

  3. Oxidation effects on cleaved multiple quantum well surfaces in air observed by scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Howells, S.; Gallagher, M. J.; Chen, T.; Pax, P.; Sarid, D.

    1992-08-01

    The paper presents the first atomic force microscopy (AFM) images of cleaved InGaAs/InP multiple quantum wells and compares them with scanning tunneling microscopy (STM) images taken of the same heterostructure. The images were stable in air for over a day. Based on these results, it is proposed that the mechanism for contrast in the images is due to an oxide layer that grows primarily on the InGaAs wells and not on the InP barriers. Both STM and AFM clearly resolve the individual wells of the heterostructure, although STM measured a larger corrugation than an AFM. STM also exhibited superior lateral resolution of about 2 nm, while AFM had a lateral resolution of approximately 6 nm.

  4. Multiplicative effect of inhaled plutonium oxide and benzo (a) pyrene on lung carcinogenesis in rats.

    PubMed Central

    Métivier, H.; Wahrendorf, J.; Masse, R.

    1984-01-01

    This study describes the effect of intratracheal instillations (2 X 5 mg) of benzo(a)pyrene (B(a)P) on lung carcinogenesis in rats which had previously inhaled different levels of 239 plutonium oxide (220, 630, 6300 Bq, initial lung burden). Survival decreased with increasing PuO2 exposure and additional B(a)P exposure. The incidence of malignant lung tumours, adjusted for differences in survival, increased in a dose-related fashion with PuO2 dose and was elevated in the presence of additional B(a)P exposure. A multiplicative relative risk model was found to describe reasonably well the observed joint effect. The practical implications of these findings are discussed. PMID:6087866

  5. Global methane and nitrous oxide emissions from terrestrial ecosystems due to multiple environmental changes

    SciTech Connect

    Tian, Hanqin; Chen, Guangsheng; Lu, Chaoqun; Xu, Xiaofeng; Ren, Wei; Zhang, Bowen; Banger, Kamaljit; Tao, Bo; Pan, Shufen; Chu, Mingliang; Zhang, Chi; Bruhwiler, Lori; Wofsy, Steven

    2015-03-16

    Greenhouse gas (GHG)-induced climate change is among the most pressing sustainability challenges facing humanity today, posing serious risks for ecosystem health. Methane (CH4) and nitrous oxide (N2O) are the two most important GHGs after carbon dioxide (CO2), but their regional and global budgets are not well known. In this paper, we applied a process-based coupled biogeochemical model to concurrently estimate the magnitude and spatial and temporal patterns of CH4 and N2O fluxes as driven by multiple environmental changes, including climate variability, rising atmospheric CO2, increasing nitrogen deposition, tropospheric ozone pollution, land use change, and nitrogen fertilizer use.

  6. Predicting Reduction Rates of Energetic Nitroaromatic Compounds Using Calculated One-Electron Reduction Potentials

    DOE PAGES

    Salter-Blanc, Alexandra; Bylaska, Eric J.; Johnston, Hayley; ...

    2015-02-11

    The evaluation of new energetic nitroaromatic compounds (NACs) for use in green munitions formulations requires models that can predict their environmental fate. The susceptibility of energetic NACs to nitro reduction might be predicted from correlations between rate constants (k) for this reaction and one-electron reduction potentials (E1NAC) / 0.059 V, but the mechanistic implications of such correlations are inconsistent with evidence from other methods. To address this inconsistency, we have reevaluated existing kinetic data using a (non-linear) free-energy relationship (FER) based on the Marcus theory of outer-sphere electron transfer. For most reductants, the results are inconsistent with rate limitation bymore » an initial, outer-sphere electron transfer, suggesting that the strong correlation between k and E1NAC is justified only as an empirical model. This empirical correlation was used to calibrate a new quantitative structure-activity relationship (QSAR) using previously reported values of k for non-energetic NAC reduction by Fe(II) porphyrin and newly reported values of E1NAC determined using density functional theory at the B3LYP/6-311++G(2d,2p) level with the COSMO solvation model. The QSAR was then validated for energetic NACs using newly measured kinetic data for 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), and 2,4-dinitroanisole (DNAN). The data show close agreement with the QSAR, supporting its applicability to energetic NACs.« less

  7. Predicting Reduction Rates of Energetic Nitroaromatic Compounds Using Calculated One-Electron Reduction Potentials

    SciTech Connect

    Salter-Blanc, Alexandra; Bylaska, Eric J.; Johnston, Hayley; Tratnyek, Paul G.

    2015-02-11

    The evaluation of new energetic nitroaromatic compounds (NACs) for use in green munitions formulations requires models that can predict their environmental fate. The susceptibility of energetic NACs to nitro reduction might be predicted from correlations between rate constants (k) for this reaction and one-electron reduction potentials (E1NAC) / 0.059 V, but the mechanistic implications of such correlations are inconsistent with evidence from other methods. To address this inconsistency, we have reevaluated existing kinetic data using a (non-linear) free-energy relationship (FER) based on the Marcus theory of outer-sphere electron transfer. For most reductants, the results are inconsistent with rate limitation by an initial, outer-sphere electron transfer, suggesting that the strong correlation between k and E1NAC is justified only as an empirical model. This empirical correlation was used to calibrate a new quantitative structure-activity relationship (QSAR) using previously reported values of k for non-energetic NAC reduction by Fe(II) porphyrin and newly reported values of E1NAC determined using density functional theory at the B3LYP/6-311++G(2d,2p) level with the COSMO solvation model. The QSAR was then validated for energetic NACs using newly measured kinetic data for 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), and 2,4-dinitroanisole (DNAN). The data show close agreement with the QSAR, supporting its applicability to energetic NACs.

  8. One-electron reduction of 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin: a pulse radiolysis study.

    PubMed

    Goldstein, Sara

    2011-08-18

    Geldanamycin, a benzoquinone ansamycin antibiotic, is a natural product inhibitor of Hsp90 with potent and broad anticancer properties but with unacceptable levels of hepatotoxicity. Consequently, numerous structural analogs, which differ only in their 17-substituent, have been synthesized including the water-soluble and less toxic 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG, Alvespimycin). It has been suggested that the different hepatotoxicity reflects the redox active properties of the quinone moiety. The present pulse radiolysis study was aimed at studying the one-electron reduction of 17-DMAG. The UV-visible spectrum of the semiquinone radical, its pK(a), and the second-order rate constants for the reactions of 17-DMAG with CO(2)(•-) and (CH(3))(2)C(•)OH have been obtained. The reduction potential of 17-DMAG has been determined to be -194 ± 6 mV (vs NHE) using oxygen, 1,4-naphthoquinone, and menadione as electron acceptors. This reduction potential is lower than that of O(2) demonstrating that thermodynamically the semiquinone radical can reduce O(2) to superoxide, particularly since the concentration of O(2) is expected to exceed that of the drug in cells and tissues. © 2011 American Chemical Society

  9. Polaronic Hole Localization and Multiple Hole Binding of Acceptors in Oxide Wide-Gap Semiconductors

    SciTech Connect

    Lany, S.; Zunger, A.

    2009-01-01

    Acceptor-bound holes in oxides often localize asymmetrically at one out of several equivalent oxygen ligands. Whereas Hartree-Fock (HF) theory overly favors such symmetry-broken polaronic hole localization in oxides, standard local-density (LD) calculations suffer from spurious delocalization among several oxygen sites. These opposite biases originate from the opposite curvatures of the energy as a function of the fractional occupation number n, i.e., d{sup 2}E/dn{sup 2}<0 in HF and d{sup 2}E/dn{sup 2}>0 in LD. We recover the correct linear behavior, d{sup 2}E/dn{sup 2}=0, that removes the (de)localization bias by formulating a generalized Koopmans condition. The correct description of oxygen hole localization reveals that the cation-site nominal single acceptors in ZnO, In{sub 2}O{sub 3}, and SnO{sub 2} can bind multiple holes.

  10. Modulation of physical properties of oxide thin films by multiple fields

    NASA Astrophysics Data System (ADS)

    Hua-Li, Yang; Bao-Min, Wang; Xiao-Jian, Zhu; Jie, Shang; Bin, Chen; Run-Wei, Li

    2016-06-01

    Recent studies of the modulation of physical properties in oxide thin films by multiple fields are reviewed. Some of the key issues and prospects of this area of study are also addressed. Oxide thin films exhibit versatile physical properties such as magnetism, ferroelectricity, piezoelectricity, metal-insulator transition (MIT), multiferroicity, colossal magnetoresistivity, switchable resistivity. More importantly, the exhibited multifunctionality can be tuned by various external fields, which has enabled demonstration of novel electronic devices. Project supported by the State Key Project of Fundamental Research of China (Grant No. 2012CB933004), the National Natural Science Foundation of China (Grant Nos. 11474295, 51571208, 51525103, and 11274322), Overseas, Hong Kong & Macao Scholars Collaborated Researching Fund (Grant No. 51428201), the Instrument Developing Project of the Chinese Academy of Sciences (Grant No. YZ201327), Ningbo Major Project for Science and Technology (Grant No. 2014B11011), Ningbo International Cooperation Projects (Grant Nos. 2012D10018 and 2014D10005), the Fund for Ningbo Science and Technology Innovation Team (Grant No. 2015B11001), the Youth Innovation Promotion Association of the Chinese Academy of Sciences, and the Key Research Program of the Chinese Academy of Sciences (Grant No. KJZD-EW-M05).

  11. Interactive effects of multiple climate change factors on ammonia oxidizers and denitrifiers in a temperate steppe.

    PubMed

    Zhang, Cuijing; Shen, Jupei; Sun, Yifei; Wang, Juntao; Zhang, Limei; Yang, Zhongling; Han, Hongyan; Wan, Shiqiang; He, Jizheng

    2017-03-15

    Global climate change could have profound effects on belowground microbial communities and subsequently affect soil biogeochemical processes. The interactive effects of multiple co-occurring climate change factors on microbially-mediated processes are not well understood. A four-factorial field experiment with elevated CO2, watering, nitrogen (N) addition and night warming was conducted in a temperate steppe of northern China. Real-time polymerase chain reaction and terminal-restriction fragment length polymorphism, combined with clone library techniques were applied to examine the effects of those climate change factors on N-related microbial abundance and community composition. Only the abundance of ammonia-oxidizing bacteria significantly increased by nitrogen addition and decreased by watering. The interactions of watering × warming on the bacterial amoA community and warming × nitrogen addition on the nosZ community were found. Redundancy analysis indicated that the ammonia-oxidizing archaeal community was affected by total N and total carbon, while the community of bacterial amoA and nosZ were significantly affected by soil pH. According to a structural equation modeling analysis, climate change influenced net primary production indirectly by altering microbial abundance and activities. These results indicated that microbial responses to the combination of chronic global change tend to be smaller than expected from single-factor global change manipulations.

  12. Novel multiple phosphorescence in nanostructured zinc oxide and calculations of correlated colour temperature.

    PubMed

    Das, Sagnik; Ghorai, Uttam Kumar; Dey, Rajib; Ghosh, Chandan Kumar; Pal, Mrinal

    2017-08-30

    The design and development of novel and high quantum efficiency luminescent materials, such as phosphors, having tuneability in properties, have received tremendous interest among scientists. In this paper, we have achieved for the first-time multiple phosphorescence (blue and green) having a life-time of ∼10 μs in nanostructured zinc oxide that was synthesized using an easy and facile sol-gel method. Importantly, the photoluminescence (PL) intensity and the phosphorescence life-time could be tuned by controlling the annealing temperature under a reducing atmosphere. Temperature and atmosphere dependent variation of [VO] and has been interpreted by the detailed thermodynamic analysis of defect chemistry, for the first time. These nanostructured zinc oxide particles being sufficiently large in size (around 160 nm) are extremely stable and expected to show photoluminescence for a longer period of time than nanorods and quantum dots. The quantum yield was found to be as high as 13-15% which is comparable to the order of magnitude of that of quantum dots. The calculated correlated colour temperature is found to be suitable for cool lighting applications.

  13. Targeting multiple types of tumors using NKG2D-coated iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Ru; Cook, W. James; Zhang, Tong; Sentman, Charles L.

    2014-11-01

    Iron oxide nanoparticles (IONPs) hold great potential for cancer therapy. Actively targeting IONPs to tumor cells can further increase therapeutic efficacy and decrease off-target side effects. To target tumor cells, a natural killer (NK) cell activating receptor, NKG2D, was utilized to develop pan-tumor targeting IONPs. NKG2D ligands are expressed on many tumor types and its ligands are not found on most normal tissues under steady state conditions. The data showed that mouse and human fragment crystallizable (Fc)-fusion NKG2D (Fc-NKG2D) coated IONPs (NKG2D/NPs) can target multiple NKG2D ligand positive tumor types in vitro in a dose dependent manner by magnetic cell sorting. Tumor targeting effect was robust even under a very low tumor cell to normal cell ratio and targeting efficiency correlated with NKG2D ligand expression level on tumor cells. Furthermore, the magnetic separation platform utilized to test NKG2D/NP specificity has the potential to be developed into high throughput screening strategies to identify ideal fusion proteins or antibodies for targeting IONPs. In conclusion, NKG2D/NPs can be used to target multiple tumor types and magnetic separation platform can facilitate the proof-of-concept phase of tumor targeting IONP development.

  14. Placental Endothelial Nitric Oxide Synthase in Multiple and Single Dose Betamethasone Exposed Pregnancies

    PubMed Central

    MERTZ, Heather L.; MELE, Lisa; SPONG, Catherine Y.; DUDLEY, Donald J.; WAPNER, Ronald J.; IAMS, Jay D.; SOROKIN, Yoram; PEACEMAN, Alan; LEVENO, Kenneth J.; CARITIS, Steve N.; MIODOVNIK, Menachem; MERCER, Brian M.; THORP, John M.; O'SULLIVAN, Mary J.; RAMIN, Susan M.; CARPENTER, Marshall; ROUSE, Dwight J.; SIBAI, Baha

    2011-01-01

    Objective To compare endothelial nitric oxide synthase (eNOS ) expression and capillary density (CDS) in placentas exposed to single or multiple courses of betamethasone. Study design Placental specimens exposed to single versus repeat courses of betamethasone were analyzed through immunohistochemistry and digital image quantification for eNOS and CD34. Quantified eNOS staining, calculated CDS, ratio of eNOS to CDS, and clinical characteristics were compared. Linear regression performed with these as dependent variables. Results Mean and maximum CDS were increased (p=0.013 and 0.005) and the ratio of eNOS to CDS decreased (p=0.016) in specimens exposed to 4 courses of betamethasone compared with 1 to 3 courses. Exposure to 4 courses of betamethasone was associated with increased CDS, but not with eNOS expression. Conclusion Exposure to 4 courses of betamethasone is associated with increased placental CDS. The placental effects of multiple courses of betamethasone are unrelated to eNOS expression. PMID:21529755

  15. Quantitative differentiation of multiple virus in blood using nanoporous silicon oxide immunosensor and artificial neural network.

    PubMed

    Chakraborty, W; Ray, R; Samanta, N; RoyChaudhuri, C

    2017-12-15

    In spite of the rapid developments in various nanosensor technologies, it still remains challenging to realize a reliable ultrasensitive electrical biosensing platform which will be able to detect multiple viruses in blood simultaneously with a fairly high reproducibility without using secondary labels. In this paper, we have reported quantitative differentiation of Hep-B and Hep-C viruses in blood using nanoporous silicon oxide immunosensor array and artificial neural network (ANN). The peak frequency output (fp) from the steady state sensitivity characteristics and the first cut off frequency (fc) from the transient characteristics have been considered as inputs to the multilayer ANN. Implementation of several classifier blocks in the ANN architecture and coupling them with both the sensor chips, functionalized with Hep-B and Hep-C antibodies have enabled the quantification of the viruses with an accuracy of around 95% in the range of 0.04fM-1pM and with an accuracy of around 90% beyond 1pM and within 25nM in blood serum. This is the most sensitive report on multiple virus quantification using label free method. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Quantum calculation of the second-order hyperpolarizability of chiral molecules in the "one-electron" model.

    PubMed

    Hache, F

    2010-09-23

    Quantum calculation of the hyperpolarizabilty tensor is carried out for chiral molecules displaying a "one-electron" chirality. Calculation is made possible by introducing a chiral perturbation term in the potential energy surface. We show that a one-electron chiral molecule is intrinsically nonlinear and diplays a nonzero electric chiral hyperpolarizability. Existence of magnetic contributions is discussed, and it is shown that higher-order perturbation terms are necessary to introduce such magnetic effects in the second-order hyperpolarizability.

  17. Using multiple biomarkers and determinants to obtain a better measurement of oxidative stress: a latent variable structural equation model approach.

    PubMed

    Eldridge, Ronald C; Flanders, W Dana; Bostick, Roberd M; Fedirko, Veronika; Gross, Myron; Thyagarajan, Bharat; Goodman, Michael

    2017-09-01

    Since oxidative stress involves a variety of cellular changes, no single biomarker can serve as a complete measure of this complex biological process. The analytic technique of structural equation modeling (SEM) provides a possible solution to this problem by modelling a latent (unobserved) variable constructed from the covariance of multiple biomarkers. Using three pooled datasets, we modelled a latent oxidative stress variable from five biomarkers related to oxidative stress: F2-isoprostanes (FIP), fluorescent oxidation products, mitochondrial DNA copy number, γ-tocopherol (Gtoc) and C-reactive protein (CRP, an inflammation marker closely linked to oxidative stress). We validated the latent variable by assessing its relation to pro- and anti-oxidant exposures. FIP, Gtoc and CRP characterized the latent oxidative stress variable. Obesity, smoking, aspirin use and β-carotene were statistically significantly associated with oxidative stress in the theorized directions; the same exposures were weakly and inconsistently associated with the individual biomarkers. Our results suggest that using SEM with latent variables decreases the biomarker-specific variability, and may produce a better measure of oxidative stress than do single variables. This methodology can be applied to similar areas of research in which a single biomarker is not sufficient to fully describe a complex biological phenomenon.

  18. Astragaloside IV attenuates experimental autoimmune encephalomyelitis of mice by counteracting oxidative stress at multiple levels.

    PubMed

    He, Yixin; Du, Min; Gao, Yan; Liu, Hongshuai; Wang, Hongwei; Wu, Xiaojun; Wang, Zhengtao

    2013-01-01

    Multiple sclerosis (MS) is a chronic autoimmune neuroinflammatory disease found mostly in young adults in the western world. Oxidative stress induced neuronal apoptosis plays an important role in the pathogenesis of MS. In current study, astragaloside IV (ASI), a natural saponin molecule isolated from Astragalus membranceus, given at 20 mg/kg daily attenuated the severity of experimental autoimmune encephalomyelitis (EAE) in mice significantly. Further studies disclosed that ASI treatment inhibited the increase of ROS and pro-inflammatory cytokine levels, down-regulation of SOD and GSH-Px activities, and elevation of iNOS, p53 and phosphorylated tau in central nervous system (CNS) as well as the leakage of BBB of EAE mice. Meanwhile, the decreased ratio of Bcl-2/Bax was reversed by ASI. Moreover, ASI regulated T-cell differentiation and infiltration into CNS. In neuroblast SH-SY5Y cells, ASI dose-dependently reduced cellular ROS level and phosphorylation of tau in response to hydrogen peroxide challenge by modulation of Bcl-2/Bax ratio. ASI also inhibited activation of microglia both in vivo and in vitro. iNOS up-regulation induced by IFNγ stimulation was abolished by ASI dose-dependently in BV-2 cells. In summary, ASI prevented the severity of EAE progression possibly by counterbalancing oxidative stress and its effects via reduction of cellular ROS level, enhancement of antioxidant defense system, increase of anti-apoptotic and anti-inflammatory pathways, as well as modulation of T-cell differentiation and infiltration into CNS. The study suggested ASI may be effective for clinical therapy/prevention of MS.

  19. Biodegradation of individual and multiple chlorinated aliphatic hydrocarbons by methane-oxidizing cultures.

    PubMed Central

    Chang, H L; Alvarez-Cohen, L

    1996-01-01

    The microbial degradation of chlorinated and nonchlorinated methanes, ethanes, and ethanes by a mixed methane-oxidizing culture grown under chemostat and batch conditions is evaluated and compared with that by two pure methanotrophic strains: CAC1 (isolated from the mixed culture) and Methylosinus trichosporium OB3b. With the exception of 1,1-dichloroethylene, the transformation capacity (Tc) for each chlorinated aliphatic hydrocarbon was generally found to be in inverse proportion to its chlorine content within each aliphatic group (i.e., methanes, ethanes, and ethenes), whereas similar trends were not observed for degradation rate constants. Tc trends were similar for all methane-oxidizing cultures tested. None of the cultures were able to degrade the fully chlorinated aliphatics such as perchloroethylene and carbon tetrachloride. Of the four cultures tested, the chemostat-grown mixed culture exhibited the highest Tc for trichloroethylene, cis-1,2-dichloroethylene, tetrachloroethane, 1,1,1-trichloroethane, and 1,2-dichloroethane, whereas the pure batch-grown OB3b culture exhibited the highest Tc for all other compounds tested. The product toxicity of chlorinated aliphatic hydrocarbons in a mixture containing multiple compounds was cumulative and predictable when using parameters measured from the degradation of individual compounds. The Tc for each chlorinated aliphatic hydrocarbon in a mixture (Tcmix) and the total Tc for the mixture (sigma Tcmix) are functions of the individual Tc, the initial substrate concentration (S0), and the first-order rate constant (k/Ks) of each compound in the mixture, indicating the importance of identifying the properties and compositions of all potentially degradable compounds in a contaminant mixture. PMID:8795228

  20. Oxidative stress in severe pulmonary trauma in critical ill patients. Antioxidant therapy in patients with multiple trauma--a review.

    PubMed

    Bedreag, Ovidiu Horea; Rogobete, Alexandru Florin; Sarandan, Mirela; Cradigati, Alina Carmen; Papurica, Marius; Dumbuleu, Maria Corina; Chira, Alexandru Mihai; Rosu, Oana Maria; Sandesc, Dorel

    2015-01-01

    Multiple trauma patients require extremely good management and thus, the trauma team needs to be prepared and to be up to date with the new standards of intensive therapy. Oxidative stress and free radicals represent an extremely aggressive factor to cells, having a direct consequence upon the severity of lung inflammation. Pulmonary tissue is damaged by oxidative stress, leading to biosynthesis of mediators that exacerbate inflammation modulators. The subsequent inflammation spreads throughout the body, leading most of the time to multiple organ dysfunction and death. In this paper, we briefly present an update of biochemical effects of oxidative stress and free radical damage to the pulmonary tissue in patients in critical condition in the intensive care unit. Also, we would like to present a series of active substances that substantially reduce the aggressiveness of free radicals, increasing the chances of survival.

  1. Relative antioxidant efficiency of a large series of carotenoids in terms of one electron transfer reactions.

    PubMed

    Galano, Annia

    2007-11-08

    The relative antioxidant efficiency, expressed as electron donating capability, of a large series of carotenoids has been studied using density functional theory. Their reactivity toward nine different radicals has been modeled as well as the electron transfer between pairs of carotenoids, one of which is present as a radical cation. The influence of the solvent polarity has also been studied. Torulene was found to be the most easily oxidized carotenoid, followed by lycopene. This higher reactivity is proposed in the present work for the first time, and the potential implications of such a finding are discussed. Since torulene has not been previously studied, compared to other carotenoids in terms of oxidation potentials, further experimental studies are suggested in order to confirm or reject this prediction. Ionization potential seems to be a magnitude calculable at low computational cost that correctly predicts the relative ease of oxidation in a series of carotenoids. The nuclear reorganization energy associated with electron-transfer reactions has been calculated in a very simple but apparently efficient way that allows computation of free energy barriers and relative rate constants in good agreement with the experimental values. In addition, an additive correction is proposed to include the effect of increasing the size of basis sets on the energies of Car(n) --> Car(n-1)(*+) processes. The general agreement between different calculated magnitudes and the corresponding available experimental data supports the predictions from this work.

  2. Depression's multiple comorbidities explained by (neuro)inflammatory and oxidative & nitrosative stress pathways.

    PubMed

    Maes, Michael; Kubera, Marta; Obuchowiczwa, Ewa; Goehler, Lisa; Brzeszcz, Joanna

    2011-01-01

    There is now evidence that depression, as characterized by melancholic symptoms, anxiety, and fatigue and somatic (F&S) symptoms, is the clinical expression of peripheral cell-mediated activation, inflammation and induction of oxidative and nitrosative stress (IO&NS) pathways and of central microglial activation, decreased neurogenesis and increased apoptosis. This review gives an explanation for the multiple "co-morbidities" between depression and a large variety of a) brain disorders related to neurodegeneration, e.g. Alzheimer's, Parkinson's and Huntington's disease, multiple sclerosis and stroke; b) medical disorders, such as cardiovascular disorder, chronic fatigue syndrome, chronic obstructive pulmonary disease, rheumatoid arthritis, psoriasis, systemic lupus erythematosus, inflammatory bowel disease, irritable bowel syndrome, leaky gut, diabetes type 1 and 2, obesity and the metabolic syndrome, and HIV infection; and c) conditions, such as hemodialysis, interferon-α-based immunotherapy, the postnatal period and psychosocial stressors. The common denominator of all those disorders/conditions is the presence of microglial activation and/or activation of peripheral IO&NS pathways. There is evidence that shared peripheral and / or central IO&NS pathways underpin the pathophysiology of depression and the previously mentioned disorders and that activation of these IO&NS pathways contributes to shared risk. The IO&NS pathways function as a smoke sensor that detect threats in the peripheral and central parts of the body and signal these threats as melancholic, anxiety, and fatigue and somatic (F&S) symptoms. The presence of concomitant depression is strongly associated with a lower quality of life and increased morbidity and mortality in medical disorders. This may be explained since depression contributes to increased (neuro)inflammatory burden and may therefore drive the inflammatory and degenerative progression. It is concluded that the activation of peripheral

  3. Pluriformity of inflammation in multiple sclerosis shown by ultra-small iron oxide particle enhancement.

    PubMed

    Vellinga, Machteld M; Oude Engberink, Raoul D; Seewann, Alexandra; Pouwels, Petra J W; Wattjes, Mike P; van der Pol, Susanne M A; Pering, Christiane; Polman, Chris H; de Vries, Helga E; Geurts, Jeroen J G; Barkhof, Frederik

    2008-03-01

    Gadolinium-DTPA (Gd-DTPA) is routinely used as a marker for inflammation in MRI to visualize breakdown of the blood-brain barrier (BBB) in multiple sclerosis. Recent data suggest that ultra-small superparamagnetic particles of iron oxide (USPIO) can be used to visualize cellular infiltration, another aspect of inflammation. This project aimed to compare the novel USPIO particle SHU555C to the longitudinal pattern of Gd-DTPA enhancement in multiple sclerosis. Nineteen relapsing-remitting patients were screened monthly using Gd-enhanced MRI. In case of new enhancing lesions, USPIO were injected and 24 h later, MRI was performed and blood was collected to confirm USPIO loading of circulating monocytes. Lesion development was monitored by 3 monthly Gd-DTPA-enhanced scans and a final scan 7-11 months after injection. USPIO-enhancement was observed as hyperintensity on T1-weighted images, whereas no signal changes were observed on T2-weighted-gradient-echo images. In 14 patients with disease activity, 188 USPIO-positive lesions were seen, 144 of which were Gd-negative. By contrast, there were a total of 59 Gd-positive lesions, 15 of which were USPIO negative. Three patterns of USPIO-enhancement were seen: (i) focal enhancement; (ii) ring-like enhancement and (iii) return to isointensity of a previously hypointense lesion. The latter pattern was most frequently observed for lesions that turned out to be transiently hypointense on follow-up scans, and ring-enhancing lesions were less likely to evolve into black holes at follow-up than lesions without ring-like USPIO-enhancement; we speculate this to be associated with repair. In 4% of the USPIO-positive/Gd negative lesions, USPIO-enhancement preceded Gd-enhancement by 1 month. USPIO-enhancement remained visible for up to 3 months in 1.5% of all USPIO-positive lesions. In 29% of the lesions enhancing with both contrast agents, USPIO-enhancement persisted whereas Gd-enhancement had already resolved. In conclusion, the new

  4. The Application of Multiple Reaction Monitoring to Assess Apo A-I Methionine Oxidations in Diabetes and Cardiovascular Disease

    PubMed Central

    Yassine, Hussein N.; Jackson, Angela M.; Reaven, Peter D.; Nedelkov, Dobrin; Nelson, Randall W.; Lau, Serrine S.; Borchers, Christoph H.

    2014-01-01

    The oxidative modification of apolipoprotein A-I ‘s methionine148(M148) is associated with defective HDL function in vitro. Multiple Reaction Monitoring (MRM) is a mass spectrometric technique that can be used to quantitate post-translational modifications. In this study, we developed an MRM assay to monitor the abundance ratio of the peptide containing oxidized M148 to the native peptide in Apo A-I. Measurement of the oxidized-to-unoxidized-M148 ratio was reproducible (CV<5%). The extent of methionine M148 oxidation in the HDL of healthy controls, and type 2 diabetic participants with and without prior cardiovascular events (CVD) were then examined. The results suggest a significant increase in the relative ratio of the peptide containing oxidized M148 to the unmodified peptide in the HDL of participants with diabetes and CVD (p<0.001), compared to participants without CVD. Monitoring the abundance ratio of the peptides containing oxidized and unoxidized M148 by MRM provides a means of examining the relationship between M148 oxidation and vascular complications in CVD. PMID:25705587

  5. Metal mobilization by iron- and sulfur-oxidizing bacteria in a multiple extreme mine tailings in the Atacama Desert, Chile.

    PubMed

    Korehi, H; Blöthe, M; Sitnikova, M A; Dold, B; Schippers, A

    2013-03-05

    The marine shore sulfidic mine tailings dump at the Chañaral Bay in the Atacama Desert, northern Chile, is characterized by extreme acidity, high salinity, and high heavy metals concentrations. Due to pyrite oxidation, metals (especially copper) are mobilized under acidic conditions and transported toward the tailings surface and precipitate as secondary minerals (Dold, Environ. Sci. Technol. 2006, 40, 752-758.). Depth profiles of total cell counts in this almost organic-carbon free multiple extreme environment showed variable numbers with up to 10(8) cells g(-1) dry weight for 50 samples at four sites. Real-time PCR quantification and bacterial 16S rRNA gene diversity analysis via clone libraries revealed a dominance of Bacteria over Archaea and the frequent occurrence of the acidophilic iron(II)- and sulfur-oxidizing and iron(III)-reducing genera Acidithiobacillus, Alicyclobacillus, and Sulfobacillus. Acidophilic chemolithoautotrophic iron(II)-oxidizing bacteria were also frequently found via most-probable-number (MPN) cultivation. Halotolerant iron(II)-oxidizers in enrichment cultures were active at NaCl concentrations up to 1 M. Maximal microcalorimetrically determined pyrite oxidation rates coincided with maxima of the pyrite content, total cell counts, and MPN of iron(II)-oxidizers. These findings indicate that microbial pyrite oxidation and metal mobilization preferentially occur in distinct tailings layers at high salinity. Microorganisms for biomining with seawater salt concentrations obviously exist in nature.

  6. Disease progression and oxidative stress are associated with higher serum ferritin levels in patients with multiple sclerosis.

    PubMed

    Ferreira, Katerine Panichi Zanin; Oliveira, Sayonara R; Kallaur, Ana Paula; Kaimen-Maciel, Damacio R; Lozovoy, Marcell Alysson B; de Almeida, Elaine Regina Delicato; Morimoto, Helena Kaminami; Mezzaroba, Leda; Dichi, Isaias; Reiche, Edna Maria Vissoci; Simão, Andréa Name Colado

    2017-02-15

    Hyperferritinemia and oxidative stress have been implicated in the pathogenesis of multiple sclerosis (MS). The aim of the present study was to evaluate the serum levels of ferritin and to verify their association with oxidative stress markers and MS progression. This study included 164 MS patients, which were divided in two groups according to their levels of ferritin (cut off 125.6μg/L). Oxidative stress was evaluated by tert-butyl hydroperoxide-initiated chemiluminescence (CL-LOOH), advanced oxidation protein products (AOPP), carbonyl protein, nitric oxide metabolites (NOx), sulfhydryl groups of protein and total radical-trapping antioxidant parameter (TRAP). MS patients with elevated levels of ferritin showed higher disease progression (p=0.030), AOPP (p=0.001), and lower plasma NOx levels (p=0.031) and TRAP (p=0.006) than MS patients with lower ferritin levels. The multivariate binary logistic regression analysis showed that increased AOPP and progression of disease were significantly and positively associated with increase of ferritin. The combination of serum ferritin levels and oxidative stress markers were responsible for 13,9% in the disease progression. In conclusion, our results suggest that ferritin could aggravate oxidative stress in patients with MS and contribute to progression of disease. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Simultaneous Bioreduction of Multiple Oxidized Contaminants Using a Membrane Biofilm Reactor.

    PubMed

    Li, Haixiang; Lin, Hua; Xu, Xiaoyin; Jiang, Minmin; Chang, Chein-Chi; Xia, Siqing

    2017-02-01

      This study tests a hydrogen-based membrane biofilm reactor (MBfR) to investigate simultaneous bioreduction of selected oxidized contaminants, including nitrate (-N), sulfate (), bromate (), chromate (Cr(VI)) and para-chloronitrobenzene (p-CNB). The experiments demonstrate that MBfR can achieve high performance for contaminants bioreduction to harmless or immobile forms in 240 days, with a maximum reduction fluxes of 0.901 g -N/m2·d, 1.573 g /m2·d, 0.009 g /m2·d, 0.022 g Cr(VI)/m2·d, and 0.043 g p-CNB/m2·d. Increasing H2 pressure and decreasing influent surface loading enhanced removal efficiency of the reactor. Flux analysis indicates that nitrate and sulfate reductions competed more strongly than , Cr(VI) and p-CNB reduction. The average H2 utilization rate, H2 flux, and H2 utilization efficiency of the reactor were 0.026 to 0.052 mg H2/cm3·d, 0.024 to 0.046 mg H2/cm2·d, and 97.5% to 99.3% (nearly 100%). Results show the hydrogen-based MBfR may be suitable for removing multiple oxidized contaminants in drinking water or groundwater.

  8. HIGH EFFICIENCY, LOW EMISSIONS, SOLID OXIDE FUEL CELL SYSTEMS FOR MULTIPLE APPLICATIONS

    SciTech Connect

    Sara Ward; Michael A. Petrik

    2004-07-28

    Technology Management Inc. (TMI), teamed with the Ohio Office of Energy Efficiency and Renewable Energy, has engineered, constructed, and demonstrated a stationary, low power, multi-module solid oxide fuel cell (SOFC) prototype system operating on propane and natural gas. Under Phase I, TMI successfully operated two systems in parallel, in conjunction with a single DC-AC inverter and battery bus, and produced net AC electricity. Phase II testing expanded to include alternative and renewable fuels typically available in rural regions of Ohio. The commercial system is expected to have ultra-low pollution, high efficiency, and low noise. The TMI SOFC uses a solid ceramic electrolyte operating at high temperature (800-1000 C) which electrochemically converts gaseous fuels (hydrogen or mixed gases) and oxygen into electricity. The TMI system design oxidizes fuel primarily via electrochemical reactions and uses no burners (which pollute and consume fuel)--resulting in extremely clean exhaust. The use of proprietary sulfur tolerant materials developed by TMI allows system operation without additional fuel pre-processing or sulfur removal. Further, the combination of high operating temperatures and solid state operation increases the potential for higher reliability and efficiencies compared to other types of fuel cells. Applications for the TMI SOFC system cover a wide range of transportation, building, industrial, and military market sectors. A generic technology, fuel cells have the potential to be embodied into multiple products specific to Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) program areas including: Fuel Cells and Microturbines, School Buildings, Transportation, and Bioenergy. This program focused on low power stationary applications using a multi-module system operating on a range of common fuels. By producing clean electricity more efficiently (thus using less fuel), fuel cells have the triple effect of cleaning up the

  9. Multiplicity

    DTIC Science & Technology

    1991-04-01

    practice as a "[descent] into that inner circle of the Inferno where the damned endlessly degate multiplicity for sentencing." United States v. Barnard...select the charges to be brought in a particular case"). 19 Brown v. Ohio, 432 U.S. 161, 165 (1977). 20 Whalen v. United States, 445 U.S. at 689. 21...parte Lange, 8-5 U.S. (19 Wall.) 163 (1874). Cf. Brown v. Ohio, 432 U.S. at 165 ("once the legislature has acted courts may not impose more than one

  10. NADPH oxidase expression in active multiple sclerosis lesions in relation to oxidative tissue damage and mitochondrial injury.

    PubMed

    Fischer, Marie T; Sharma, Rakhi; Lim, Jamie L; Haider, Lukas; Frischer, Josa M; Drexhage, Joost; Mahad, Don; Bradl, Monika; van Horssen, Jack; Lassmann, Hans

    2012-03-01

    Multiple sclerosis is a chronic inflammatory disease of the central nervous system, associated with demyelination and neurodegeneration. The mechanisms of tissue injury are poorly understood, but recent data suggest that mitochondrial injury may play an important role in this process. Mitochondrial injury can be triggered by reactive oxygen and nitric oxide species, and we recently provided evidence for oxidative damage of oligodendrocytes and dystrophic axons in early stages of active multiple sclerosis lesions. In this study, we identified potential sources of reactive oxygen and nitrogen species through gene expression in carefully staged and dissected lesion areas and by immunohistochemical analysis of protein expression. Genome-wide microarrays confirmed mitochondrial injury in active multiple sclerosis lesions, which may serve as an important source of reactive oxygen species. In addition, we found differences in the gene expression levels of various nicotinamide adenine dinucleotide phosphate oxidase subunits between initial multiple sclerosis lesions and control white matter. These results were confirmed at the protein level by means of immunohistochemistry, showing upregulation of the subunits gp91phox, p22phox, p47phox, nicotinamide adenine dinucleotide phosphate oxidase 1 and nicotinamide adenine dinucleotide phosphate oxidase organizer 1 in activated microglia in classical active as well as slowly expanding lesions. The subunits gp91phox and p22phox were constitutively expressed in microglia and were upregulated in the initial lesion. In contrast, p47phox, nicotinamide adenine dinucleotide phosphate oxidase 1 and nicotinamide adenine dinucleotide phosphate oxidase organizer 1 expression were more restricted to the zone of initial damage or to lesions from patients with acute or early relapsing/remitting multiple sclerosis. Double labelling showed co-expression of the nicotinamide adenine dinucleotide phosphate oxidase subunits in activated microglia and

  11. NADPH oxidase expression in active multiple sclerosis lesions in relation to oxidative tissue damage and mitochondrial injury

    PubMed Central

    Fischer, Marie T.; Sharma, Rakhi; Lim, Jamie L.; Haider, Lukas; Frischer, Josa M.; Drexhage, Joost; Mahad, Don; Bradl, Monika; van Horssen, Jack

    2012-01-01

    Multiple sclerosis is a chronic inflammatory disease of the central nervous system, associated with demyelination and neurodegeneration. The mechanisms of tissue injury are poorly understood, but recent data suggest that mitochondrial injury may play an important role in this process. Mitochondrial injury can be triggered by reactive oxygen and nitric oxide species, and we recently provided evidence for oxidative damage of oligodendrocytes and dystrophic axons in early stages of active multiple sclerosis lesions. In this study, we identified potential sources of reactive oxygen and nitrogen species through gene expression in carefully staged and dissected lesion areas and by immunohistochemical analysis of protein expression. Genome-wide microarrays confirmed mitochondrial injury in active multiple sclerosis lesions, which may serve as an important source of reactive oxygen species. In addition, we found differences in the gene expression levels of various nicotinamide adenine dinucleotide phosphate oxidase subunits between initial multiple sclerosis lesions and control white matter. These results were confirmed at the protein level by means of immunohistochemistry, showing upregulation of the subunits gp91phox, p22phox, p47phox, nicotinamide adenine dinucleotide phosphate oxidase 1 and nicotinamide adenine dinucleotide phosphate oxidase organizer 1 in activated microglia in classical active as well as slowly expanding lesions. The subunits gp91phox and p22phox were constitutively expressed in microglia and were upregulated in the initial lesion. In contrast, p47phox, nicotinamide adenine dinucleotide phosphate oxidase 1 and nicotinamide adenine dinucleotide phosphate oxidase organizer 1 expression were more restricted to the zone of initial damage or to lesions from patients with acute or early relapsing/remitting multiple sclerosis. Double labelling showed co-expression of the nicotinamide adenine dinucleotide phosphate oxidase subunits in activated microglia and

  12. Simultaneous analysis of multiple lipid oxidation products in vivo by liquid chromatographic-mass spectrometry (LC-MS).

    PubMed

    Yin, Huiyong; Davis, Todd; Porter, Ned A

    2010-01-01

    Free radical-induced oxidation of polyunsaturated fatty acid (PUFAs) has been linked to a number of human diseases including atherosclerosis and neurodegenerative disorders. Oxidation of PUFAs generates hydroperoxides and cyclic peroxides that are reduced to lipid alcohol, such as hydroxyeicosatetraenoic acid (HETEs), and isoprostanes (IsoPs) respectively. The IsoPs are isomers of prostaglandins that are generated from autoxidation of arachidonic acid (C20:4). Quantification of F(2)-IsoPs has been regarded as the "gold standard" to assess oxidative stress status in various human diseases. We herein report the protocol of analyzing HETEs and F(2)-IsoPs using a triple quadrupole mass spectrometer coupled to reverse phase liquid chromatography. The selected reaction monitoring (SRM) mode selects the parent ion of interest in the first Quad (m/z 319 for HETE and m/z 353 for F(2)-IsoPs) and fragments it in the second while an ion characteristic of the analyte of interest is monitored in the third Quad. This highly selective technique permits the simultaneous analysis of multiple oxidation products such as the HETEs and F(2)-IsoPs. This LC-MS technique can be applied to study the free radical oxidation mechanism in vitro and assess the oxidative stress status in biological tissues and fluids.

  13. Origin of Multiple Peaks in the Potentiodynamic Oxidation of CO Adlayers on Pt and Ru-Modified Pt Electrodes

    SciTech Connect

    Wang, Hongsen; Abruña, Héctor D.

    2015-05-21

    The study of the electrooxidation mechanism of COad on Pt based catalysts is very important for designing more effective CO-tolerant electrocatalysts for fuel cells. We have studied the origin of multiple peaks in the cyclic voltammograms of CO stripping from polycrystalline Pt and Ru modified polycrystalline Pt (Pt/Ru) surfaces in both acidic and alkaline media by differential electrochemical mass spectrometry (DEMS), DFT calculations, and kinetic Monte Carlo (KMC) simulations. A new COad electrooxidation kinetic model on heterogeneous Pt and Pt/Ru catalysts is proposed to account for the multiple peaks experimentally observed. In this model, OH species prefer to adsorb at low-coordination sites or Ru sites and, thus, suppress CO repopulation from high-coordination sites onto these sites. Therefore, COad oxidation occurs on different facets or regions, leading to multiplicity of CO stripping peaks. This work provides a new insight into the CO electrooxidation mechanism and kinetics on heterogeneous catalysts.

  14. Stockholder projector analysis: A Hilbert-space partitioning of the molecular one-electron density matrix with orthogonal projectors

    NASA Astrophysics Data System (ADS)

    Vanfleteren, Diederik; Van Neck, Dimitri; Bultinck, Patrick; Ayers, Paul W.; Waroquier, Michel

    2012-01-01

    A previously introduced partitioning of the molecular one-electron density matrix over atoms and bonds [D. Vanfleteren et al., J. Chem. Phys. 133, 231103 (2010)] is investigated in detail. Orthogonal projection operators are used to define atomic subspaces, as in Natural Population Analysis. The orthogonal projection operators are constructed with a recursive scheme. These operators are chemically relevant and obey a stockholder principle, familiar from the Hirshfeld-I partitioning of the electron density. The stockholder principle is extended to density matrices, where the orthogonal projectors are considered to be atomic fractions of the summed contributions. All calculations are performed as matrix manipulations in one-electron Hilbert space. Mathematical proofs and numerical evidence concerning this recursive scheme are provided in the present paper. The advantages associated with the use of these stockholder projection operators are examined with respect to covalent bond orders, bond polarization, and transferability.

  15. R-matrix-incorporating-time theory of one-electron atomic and molecular systems in intense laser fields

    NASA Astrophysics Data System (ADS)

    Broin, Cathal Ó.; Nikolopoulos, L. A. A.

    2017-02-01

    In this thesis tutorial we discuss the R-matrix-incorporating-time ab initio theoretical framework for the solution of the time-dependent Schrödinger equation of one-electron atomic and molecular systems under strong electromagnetic fields. Within this approach, a division-of-space method is developed with the configuration space of the electron’s coordinates separated over two regions, the inner and outer regions. In the inner region the quantum system’s time-dependent wavefunction is expanded on the eigenstate basis set of its field-free Hamiltonian representation while in the outer region its grid representation is considered. The present tutorial describes in detail the theoretical formulation for one-electron quantum systems. Example calculations are discussed for atomic hydrogen, H, and the molecular hydrogen ion, {{{H}}}2+, in intense laser fields.

  16. Exposure of Phytopathogenic Xanthomonas spp. to Lethal Concentrations of Multiple Oxidants Affects Bacterial Survival in a Complex Manner

    PubMed Central

    Sriprang, Rutchadaporn; Vattanaviboon, Paiboon; Mongkolsuk, Skorn

    2000-01-01

    During plant-microbe interactions and in the environment, Xanthomonas campestris pv. phaseoli is likely to be exposed to high concentrations of multiple oxidants. Here, we show that simultaneous exposures of the bacteria to multiple oxidants affects cell survival in a complex manner. A superoxide generator (menadione) enhanced the lethal effect of an organic peroxide (tert-butyl hydroperoxide) by 1,000-fold; conversely, treatment of cells with menadione plus H2O2 resulted in 100-fold protection compared to that for cells treated with the individual oxidants. Treatment of X. campestris with a combination of H2O2 and tert-butyl hydroperoxide elicited no additive or protective effect. High levels of catalase alone are sufficient to protect cells against the lethal effect of menadione plus H2O2 and tert-butyl hydroperoxide plus H2O2. These data suggest that H2O2 is the lethal agent responsible for killing the bacteria as a result of these treatments. However, increased expression of individual genes for peroxide (alkyl hydroperoxide reductase, catalase)- and superoxide (superoxide dismutase)-scavenging enzymes or concerted induction of oxidative stress-protective genes by menadione gave no protection against killing by a combination of menadione plus tert-butyl hydroperoxide. However, X. campestris cells in the stationary phase and a spontaneous H2O2-resistant mutant (X. campestris pv. phaseoli HR) were more resistant to killing by menadione plus tert-butyl hydroperoxide. These findings give new insight into oxidant killing of Xanthomonas spp. that could be generally applied to other bacteria. PMID:10966423

  17. Aptamer-Conjugated Graphene Oxide Membranes for Highly Efficient Capture and Accurate Identification of Multiple Types of Circulating Tumor Cells

    PubMed Central

    2016-01-01

    Tumor metastasis is responsible for 1 in 4 deaths in the United States. Though it has been well-documented over past two decades that circulating tumor cells (CTCs) in blood can be used as a biomarker for metastatic cancer, there are enormous challenges in capturing and identifying CTCs with sufficient sensitivity and specificity. Because of the heterogeneous expression of CTC markers, it is now well understood that a single CTC marker is insufficient to capture all CTCs from the blood. Driven by the clear need, this study reports for the first time highly efficient capture and accurate identification of multiple types of CTCs from infected blood using aptamer-modified porous graphene oxide membranes. The results demonstrate that dye-modified S6, A9, and YJ-1 aptamers attached to 20–40 μm porous garphene oxide membranes are capable of capturing multiple types of tumor cells (SKBR3 breast cancer cells, LNCaP prostate cancer cells, and SW-948 colon cancer cells) selectively and simultaneously from infected blood. Our result shows that the capture efficiency of graphene oxide membranes is ∼95% for multiple types of tumor cells; for each tumor concentration, 10 cells are present per milliliter of blood sample. The selectivity of our assay for capturing targeted tumor cells has been demonstrated using membranes without an antibody. Blood infected with different cells also has been used to demonstrate the targeted tumor cell capturing ability of aptamer-conjugated membranes. Our data also demonstrate that accurate analysis of multiple types of captured CTCs can be performed using multicolor fluorescence imaging. Aptamer-conjugated membranes reported here have good potential for the early diagnosis of diseases that are currently being detected by means of cell capture technologies. PMID:25565372

  18. Aptamer-conjugated graphene oxide membranes for highly efficient capture and accurate identification of multiple types of circulating tumor cells.

    PubMed

    Viraka Nellore, Bhanu Priya; Kanchanapally, Rajashekhar; Pramanik, Avijit; Sinha, Sudarson Sekhar; Chavva, Suhash Reddy; Hamme, Ashton; Ray, Paresh Chandra

    2015-02-18

    Tumor metastasis is responsible for 1 in 4 deaths in the United States. Though it has been well-documented over past two decades that circulating tumor cells (CTCs) in blood can be used as a biomarker for metastatic cancer, there are enormous challenges in capturing and identifying CTCs with sufficient sensitivity and specificity. Because of the heterogeneous expression of CTC markers, it is now well understood that a single CTC marker is insufficient to capture all CTCs from the blood. Driven by the clear need, this study reports for the first time highly efficient capture and accurate identification of multiple types of CTCs from infected blood using aptamer-modified porous graphene oxide membranes. The results demonstrate that dye-modified S6, A9, and YJ-1 aptamers attached to 20-40 μm porous garphene oxide membranes are capable of capturing multiple types of tumor cells (SKBR3 breast cancer cells, LNCaP prostate cancer cells, and SW-948 colon cancer cells) selectively and simultaneously from infected blood. Our result shows that the capture efficiency of graphene oxide membranes is ~95% for multiple types of tumor cells; for each tumor concentration, 10 cells are present per milliliter of blood sample. The selectivity of our assay for capturing targeted tumor cells has been demonstrated using membranes without an antibody. Blood infected with different cells also has been used to demonstrate the targeted tumor cell capturing ability of aptamer-conjugated membranes. Our data also demonstrate that accurate analysis of multiple types of captured CTCs can be performed using multicolor fluorescence imaging. Aptamer-conjugated membranes reported here have good potential for the early diagnosis of diseases that are currently being detected by means of cell capture technologies.

  19. Age-induced hair greying - the multiple effects of oxidative stress.

    PubMed

    Seiberg, M

    2013-12-01

    An obvious sign of ageing is hair greying, or the loss of pigment production and deposition within the hair shafts. Numerous mechanisms, acting at different levels and follicular locations, contribute to hair greying, ranging from melanocyte stem cells defects to follicular melanocyte death. One key issue that is in common to these processes is oxidative damage. At the hair follicle stem cells niche, oxidative stress, accelerated by B-cell lymphoma 2 gene (BCL-2) depletion, leads to selective apoptosis and diminution of melanocyte stem cells, reducing the repopulation of newly formed anagen follicles. Melanotic bulbar melanocytes express high levels of BCL-2 to enable survival from melanogenesis- and ultraviolet A (UVA)-induced reactive oxygen species (ROS) attacks. With ageing, the bulbar melanocyte expression of anti-oxidant proteins such as BCL-2, and possibly TRP-2, is reduced, and the dedicated enzymatic anti-oxidant defence system throughout the follicle weakens, resulting in enhanced oxidative stress. A marked reduction in catalase expression and activity results in millimolar accumulation of hydrogen peroxide, contributing to bulbar melanocyte malfunction and death. Interestingly, amelanotic melanocytes at the outer root sheath (ORS) are somewhat less affected by these processes and survive for longer time even within the white, ageing hair follicles. Better understanding of the overtime susceptibility of melanocytes to oxidative stress at the different follicular locations might yield clues to possible therapies for the prevention and reversal of hair greying.

  20. Modulation of cell metabolic pathways and oxidative stress signaling contribute to acquired melphalan resistance in multiple myeloma cells.

    PubMed

    Zub, Kamila Anna; Sousa, Mirta Mittelstedt Leal de; Sarno, Antonio; Sharma, Animesh; Demirovic, Aida; Rao, Shalini; Young, Clifford; Aas, Per Arne; Ericsson, Ida; Sundan, Anders; Jensen, Ole Nørregaard; Slupphaug, Geir

    2015-01-01

    Alkylating agents are widely used chemotherapeutics in the treatment of many cancers, including leukemia, lymphoma, multiple myeloma, sarcoma, lung, breast and ovarian cancer. Melphalan is the most commonly used chemotherapeutic agent against multiple myeloma. However, despite a 70-80% initial response rate, virtually all patients eventually relapse due to the emergence of drug-resistant tumour cells. By using global proteomic and transcriptomic profiling on melphalan sensitive and resistant RPMI8226 cell lines followed by functional assays, we discovered changes in cellular processes and pathways not previously associated with melphalan resistance in multiple myeloma cells, including a metabolic switch conforming to the Warburg effect (aerobic glycolysis), and an elevated oxidative stress response mediated by VEGF/IL8-signaling. In addition, up-regulated aldo-keto reductase levels of the AKR1C family involved in prostaglandin synthesis contribute to the resistant phenotype. Finally, selected metabolic and oxidative stress response enzymes were targeted by inhibitors, several of which displayed a selective cytotoxicity against the melphalan-resistant cells and should be further explored to elucidate their potential to overcome melphalan resistance.

  1. Modulation of Cell Metabolic Pathways and Oxidative Stress Signaling Contribute to Acquired Melphalan Resistance in Multiple Myeloma Cells

    PubMed Central

    Zub, Kamila Anna; de Sousa, Mirta Mittelstedt Leal; Sarno, Antonio; Sharma, Animesh; Demirovic, Aida; Rao, Shalini; Young, Clifford; Aas, Per Arne; Ericsson, Ida; Sundan, Anders; Jensen, Ole Nørregaard; Slupphaug, Geir

    2015-01-01

    Alkylating agents are widely used chemotherapeutics in the treatment of many cancers, including leukemia, lymphoma, multiple myeloma, sarcoma, lung, breast and ovarian cancer. Melphalan is the most commonly used chemotherapeutic agent against multiple myeloma. However, despite a 70–80% initial response rate, virtually all patients eventually relapse due to the emergence of drug-resistant tumour cells. By using global proteomic and transcriptomic profiling on melphalan sensitive and resistant RPMI8226 cell lines followed by functional assays, we discovered changes in cellular processes and pathways not previously associated with melphalan resistance in multiple myeloma cells, including a metabolic switch conforming to the Warburg effect (aerobic glycolysis), and an elevated oxidative stress response mediated by VEGF/IL8-signaling. In addition, up-regulated aldo-keto reductase levels of the AKR1C family involved in prostaglandin synthesis contribute to the resistant phenotype. Finally, selected metabolic and oxidative stress response enzymes were targeted by inhibitors, several of which displayed a selective cytotoxicity against the melphalan-resistant cells and should be further explored to elucidate their potential to overcome melphalan resistance. PMID:25769101

  2. Isotopic evidence of multiple controls on atmospheric oxidants over climate transitions.

    PubMed

    Geng, Lei; Murray, Lee T; Mickley, Loretta J; Lin, Pu; Fu, Qiang; Schauer, Andrew J; Alexander, Becky

    2017-06-01

    The abundance of tropospheric oxidants, such as ozone (O3) and hydroxyl (OH) and peroxy radicals (HO2 + RO2), determines the lifetimes of reduced trace gases such as methane and the production of particulate matter important for climate and human health. The response of tropospheric oxidants to climate change is poorly constrained owing to large uncertainties in the degree to which processes that influence oxidants may change with climate and owing to a lack of palaeo-records with which to constrain levels of atmospheric oxidants during past climate transitions. At present, it is thought that temperature-dependent emissions of tropospheric O3 precursors and water vapour abundance determine the climate response of oxidants, resulting in lower tropospheric O3 in cold climates while HOx (= OH + HO2 + RO2) remains relatively buffered. Here we report observations of oxygen-17 excess of nitrate (a proxy for the relative abundance of atmospheric O3 and HOx) from a Greenland ice core over the most recent glacial-interglacial cycle and for two Dansgaard-Oeschger events. We find that tropospheric oxidants are sensitive to climate change with an increase in the O3/HOx ratio in cold climates, the opposite of current expectations. We hypothesize that the observed increase in O3/HOx in cold climates is driven by enhanced stratosphere-to-troposphere transport of O3, and that reactive halogen chemistry is also enhanced in cold climates. Reactive halogens influence the oxidative capacity of the troposphere directly as oxidants themselves and indirectly via their influence on O3 and HOx. The strength of stratosphere-to-troposphere transport is largely controlled by the Brewer-Dobson circulation, which may be enhanced in colder climates owing to a stronger meridional gradient of sea surface temperatures, with implications for the response of tropospheric oxidants and stratospheric thermal and mass balance. These two processes may represent important, yet relatively

  3. Isotopic evidence of multiple controls on atmospheric oxidants over climate transitions

    NASA Astrophysics Data System (ADS)

    Geng, Lei; Murray, Lee T.; Mickley, Loretta J.; Lin, Pu; Fu, Qiang; Schauer, Andrew J.; Alexander, Becky

    2017-06-01

    The abundance of tropospheric oxidants, such as ozone (O3) and hydroxyl (OH) and peroxy radicals (HO2 + RO2), determines the lifetimes of reduced trace gases such as methane and the production of particulate matter important for climate and human health. The response of tropospheric oxidants to climate change is poorly constrained owing to large uncertainties in the degree to which processes that influence oxidants may change with climate and owing to a lack of palaeo-records with which to constrain levels of atmospheric oxidants during past climate transitions. At present, it is thought that temperature-dependent emissions of tropospheric O3 precursors and water vapour abundance determine the climate response of oxidants, resulting in lower tropospheric O3 in cold climates while HOx (= OH + HO2 + RO2) remains relatively buffered. Here we report observations of oxygen-17 excess of nitrate (a proxy for the relative abundance of atmospheric O3 and HOx) from a Greenland ice core over the most recent glacial-interglacial cycle and for two Dansgaard-Oeschger events. We find that tropospheric oxidants are sensitive to climate change with an increase in the O3/HOx ratio in cold climates, the opposite of current expectations. We hypothesize that the observed increase in O3/HOx in cold climates is driven by enhanced stratosphere-to-troposphere transport of O3, and that reactive halogen chemistry is also enhanced in cold climates. Reactive halogens influence the oxidative capacity of the troposphere directly as oxidants themselves and indirectly via their influence on O3 and HOx. The strength of stratosphere-to-troposphere transport is largely controlled by the Brewer-Dobson circulation, which may be enhanced in colder climates owing to a stronger meridional gradient of sea surface temperatures, with implications for the response of tropospheric oxidants and stratospheric thermal and mass balance. These two processes may represent important, yet relatively

  4. Experimental characterization of the dominant multiple nodes charge collection mechanism in metal oxide-semiconductor transistors

    NASA Astrophysics Data System (ADS)

    Song, Ruiqiang; Chen, Shuming; Chi, Yaqing; Wu, Zhenyu; Liang, Bin; Chen, Jianjun; Xu, Jingyan; Hao, Peipei; Yu, Junting

    2017-06-01

    We propose an experimental method to investigate the dominant multiple node charge collection mechanism. A transistor array-based test structure is used to distinguish charge collection owing to the drift-diffusion and parasitic bipolar amplification effect. Heavy ion experimental results confirm that drift-diffusion dominates multiple node charge collection at low linear energy transfer (LET). However, the parasitic bipolar amplification effect dominates it at high LET. We also propose simple equations to determine the critical LET which may change the dominant multiple node charge collection mechanism. The calculated LET value is consistent with the heavy ion experimental results.

  5. Hybrid functional for correlated electrons in the projector augmented-wave formalism: Study of multiple minima for actinide oxides

    NASA Astrophysics Data System (ADS)

    Jollet, F.; Jomard, G.; Amadon, B.; Crocombette, J. P.; Torumba, D.

    2009-12-01

    Exact (Hartree-Fock) exchange for correlated electrons is implemented to describe correlated orbitals in the projector augmented-waves (PAW) framework, as suggested recently in another context [P. Novák , Phys. Status Solidi B 243, 563 (2006)]. Hartree-Fock exchange energy is applied to strongly correlated electrons only inside the PAW atomic spheres. This allows the use of PBE0 hybrid exchange-correlation functional for correlated electrons. This method is tested on NiO and results agree well with already published results and generalized gradient approximation, GGA+U calculations. It is then applied to plutonium oxides and UO2 for which the results are comparable with the ones of GGA+U calculations but without adjustable parameter. As evidenced in the uranium oxide case, the occurrence of multiple energy minima may lead to very different results depending on the initial electronic configurations and on the symmetries taken into account in the calculation.

  6. Effect of temperature in multiple biomarkers of oxidative stress in coastal shrimp.

    PubMed

    Vinagre, Catarina; Madeira, Diana; Mendonça, Vanessa; Dias, Marta; Roma, Joma; Diniz, Mário S

    2014-04-01

    Various studies in captivity and in the wild have pointed to the effect of season, and temperature in particular, in the levels of the oxidative stress biomarkers currently used for environmental quality assessment. However, knowledge on how temperature affects the oxidative stress response is unavailable for most species. This study investigated the effect of increasing temperature on lipid peroxidation, catalase activity, superoxide dismutase and glutathione-S-transferase in the shrimps, Palaemon elegans and Palaemon serratus. It was concluded that increasing temperatures significantly affect all the biomarkers tested in both species, with the exception of superoxide dismutase in P. serratus which was not affected by temperature. The oxidative stress response was more intense in P. elegans, than in P. serratus, producing higher peaks of all biomarkers at temperatures between 22°C and 26°C, followed by low levels at higher temperatures. It was concluded that monitoring of ecosystems using oxidative stress biomarkers should take into account the species and thermal history of the organisms. Sampling should be avoided during heat waves and immediately after heat waves.

  7. Scavenging of the one-electron reduction product from nisoldipine with relevant thiols: electrochemical and EPR spectroscopic evidences.

    PubMed

    Núñez-Vergara, L J; Díaz-Araya, G; Olea-Azar, C; Atria, A M; Bollo-Dragnic, S; Squella, J A

    1998-11-01

    To determine the formation of the one-electron reduction product from nisoldipine and its reactivity with relevant thiols in mixed medium. Cyclic voltammetry (CV) and electron paramagnetic resonance (EPR) techniques were used to determine the one-electron reduction product corresponding to the nitro radical anion. CV was employed to assess both the rate constants corresponding to the decay of the radicals and its interaction with relevant thiols. The nisoldipine radical anion follows second order kinetics, with an association rate constant of 283+/-16 l mol(-1) sec(-1). Nitro radical anion from nisoldipine significantly reacted with thiol compounds. This reactivity was significantly higher than the natural decay of the radical in mixed medium. EPR spectra recorded in situ using DMF/ 0.1 N NaOH (pH 13) confirmed the formation of the nitro radical anion, giving a well-resolved spectra in 35 lines using 0.1 G modulation. Electrochemical and EPR data indicated that all the tested thiols scavenged the nitro radical anion from nisoldipine. The following tentative order of reactivity towards the thiols can be proposed: cysteamine approximately glutathione > N-acetylcysteine > captopril > penicillamine.

  8. One-electron pseudopotential investigation of the RbAr and FrAr van der Waals systems

    NASA Astrophysics Data System (ADS)

    Dhiflaoui, J.; Berriche, H.

    2012-12-01

    The potential energy curves of the ground state and many excited states of RbAr and FrAr van der Waals systems have been determined using a one-electron pseudopotential approach. The pseudopotential technique is used to replace the effect of the Rb+ and Fr+ cores and the electron-Ar interaction. In addition a core-core interaction is included. This has permitted to reduce the number of active electrons of the RbAr and FrAr systems to only one electron, the valence electron. This has led to use very large basis sets for Rb, Fr and Ar atoms. In this context, the potential energy curves of the ground and many excited states are performed at the SCF level. The core-core interactions for Rb+Ar and Fr+Ar are included using the CCSD(T) accurate potentials of Hickling et al. [H. Hickling, L. Viehland, D. Shepherd, P. Soldan, E. Lee and T. Wright, Phys. Chem. Chem. Phys. 6 (2004) 4233]. In addition, the spectroscopic constants of these states are derived and compared with the available theoretical works. Such comparison for RbAr has shown a very good agreement for the ground and the first excited states. However, the FrAr system was not studied previously and its spectroscopic constants are presented here for the first time.

  9. Grape skin extract mitigates tissue degeneration, genotoxicity, and oxidative status in multiple organs of rats exposed to cadmium.

    PubMed

    Boiago Gollucke, Andrea P; Claudio, Samuel R; Yamamura, Hirochi; Morais, Damila R; Bataglion, Giovana A; Eberlin, Marcos N; Aguiar, Odair; Ribeiro, Daniel A

    2016-07-28

    The aim of this study was to investigate whether grape skin extract can mitigate the noxious activities induced by cadmium exposure in multiple organs of rats. For this purpose, histopathological analysis for the liver, genotoxicity, and oxidative status in the blood and liver were investigated in this setting. A total of 20 Wistar rats weighing 250 g, on average, and 8 weeks of age were distributed into four groups (n=5) as follows: control group (nontreated group); cadmium group (Cd); and grape skin extract groups (Cd+GS) at 175 or 350 mg/l. Histopathological analysis in liver showed that animals treated with grape skin extract showed improved tissue degeneration induced by cadmium intoxication. Genetic damage was reduced in blood and hepatocytes as indicated by comet and micronucleus assays in animals treated with grape skin extract. Copper-zinc superoxide dismutase and cytochrome c gene expression increased in groups treated with grape skin extract in liver cells. Grape skin extract also reduced the 8-hydroxy-2'-deoxyguanosine levels in liver cells compared with the cadmium group. Taken together, our results indicate that grape skin extract can mitigate tissue degeneration, genotoxicity, and oxidative stress induced by cadmium exposure in multiple organs of Wistar rats.

  10. HCV Core Protein Uses Multiple Mechanisms to Induce Oxidative Stress in Human Hepatoma Huh7 Cells

    PubMed Central

    Ivanov, Alexander V.; Smirnova, Olga A.; Petrushanko, Irina Y.; Ivanova, Olga N.; Karpenko, Inna L.; Alekseeva, Ekaterina; Sominskaya, Irina; Makarov, Alexander A.; Bartosch, Birke; Kochetkov, Sergey N.; Isaguliants, Maria G.

    2015-01-01

    Hepatitis C virus (HCV) infection is accompanied by the induction of oxidative stress, mediated by several virus proteins, the most prominent being the nucleocapsid protein (HCV core). Here, using the truncated forms of HCV core, we have delineated several mechanisms by which it induces the oxidative stress. The N-terminal 36 amino acids of HCV core induced TGFβ1-dependent expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases 1 and 4, both of which independently contributed to the production of reactive oxygen species (ROS). The same fragment also induced the expression of cyclo-oxygenase 2, which, however, made no input into ROS production. Amino acids 37–191 of HCV core up-regulated the transcription of a ROS generating enzyme cytochrome P450 2E1. Furthermore, the same fragment induced the expression of endoplasmic reticulum oxidoreductin 1α. The latter triggered efflux of Ca2+ from ER to mitochondria via mitochondrial Ca2+ uniporter, leading to generation of superoxide anions, and possibly also H2O2. Suppression of any of these pathways in cells expressing the full-length core protein led to a partial inhibition of ROS production. Thus, HCV core causes oxidative stress via several independent pathways, each mediated by a distinct region of the protein. PMID:26035647

  11. Chop deletion reduces oxidative stress, improves beta cell function, and promotes cell survival in multiple mouse models of diabetes.

    PubMed

    Song, Benbo; Scheuner, Donalyn; Ron, David; Pennathur, Subramaniam; Kaufman, Randal J

    2008-10-01

    The progression from insulin resistance to type 2 diabetes is caused by the failure of pancreatic beta cells to produce sufficient levels of insulin to meet the metabolic demand. Recent studies indicate that nutrient fluctuations and insulin resistance increase proinsulin synthesis in beta cells beyond the capacity for folding of nascent polypeptides within the endoplasmic reticulum (ER) lumen, thereby disrupting ER homeostasis and triggering the unfolded protein response (UPR). Chronic ER stress promotes apoptosis, at least in part through the UPR-induced transcription factor C/EBP homologous protein (CHOP). We assessed the effect of Chop deletion in multiple mouse models of type 2 diabetes and found that Chop-/- mice had improved glycemic control and expanded beta cell mass in all conditions analyzed. In both genetic and diet-induced models of insulin resistance, CHOP deficiency improved beta cell ultrastructure and promoted cell survival. In addition, we found that isolated islets from Chop-/- mice displayed increased expression of UPR and oxidative stress response genes and reduced levels of oxidative damage. These findings suggest that CHOP is a fundamental factor that links protein misfolding in the ER to oxidative stress and apoptosis in beta cells under conditions of increased insulin demand.

  12. Visible light-induced formation of corrole-manganese(V)-oxo complexes: Observation of multiple oxidation pathways.

    PubMed

    Ka, Wai Kwong; Ngo, Fung Lee; Ranburger, Davis; Malone, Jonathan; Zhang, Rui

    2016-10-01

    Two manganese(V)-oxo corroles [Mn(V)(Cor)O] that differ in their electronic environments were produced by visible light irradiation of highly photo-labile corrole-manganese(IV) bromates. The corrole ligands under study include 5,10,15-tris(pentafluorophenyl)corrole (TPFC), and 5,10,15-triphenylcorrole (TPC). The kinetics of oxygen transfer atom (OAT) reactions with various organic reductants by these photo-generated Mn(V)(Cor)O were also studied in CH3CN and CH2Cl2 solutions. Mn(V)(Cor)O exhibits remarkable solvent and ligand effect on its reactivity and spectral behavior. In the more electron-deficient TPFC system and in the polar solvent CH3CN, Mn(V)(Cor)O returned Mn(III) corrole in the end of oxidation reactions. However, in the less polar solvent CH2Cl2 or in the less electron-deficient TPC system, Mn(IV) product was formed instead of Mn(III). Furthermore, with the same substrates and in the same solvent, the order of reactivity of Mn(V)(Cor)O was TPC>TPFC, which is inverted from that expected based on the electron-demand of corrole ligands. Our spectral and kinetic results in this study provide compelling evidence in favor of multiple oxidation pathways, where Mn(V)(Cor)O may serve as direct two-electron oxidant or undergo a disproportionation reaction to form a manganese(VI)-oxo corrole as the true oxidant. The choice of pathways is strongly dependent on the nature of the solvent and the corrole ligand.

  13. Barley has two peroxisomal ABC transporters with multiple functions in β-oxidation

    PubMed Central

    Mendiondo, Guillermina M.; Medhurst, Anne; van Roermund, Carlo W.; Zhang, Xuebin; Devonshire, Jean; Scholefield, Duncan; Fernández, José; Axcell, Barry; Ramsay, Luke; Waterham, Hans R.; Waugh, Robbie; Theodoulou, Frederica L.; Holdsworth, Michael J.

    2014-01-01

    In oilseed plants, peroxisomal β-oxidation functions not only in lipid catabolism but also in jasmonate biosynthesis and metabolism of pro-auxins. Subfamily D ATP-binding cassette (ABC) transporters mediate import of β-oxidation substrates into the peroxisome, and the Arabidopsis ABCD protein, COMATOSE (CTS), is essential for this function. Here, the roles of peroxisomal ABCD transporters were investigated in barley, where the main storage compound is starch. Barley has two CTS homologues, designated HvABCD1 and HvABCD2, which are widely expressed and present in embryo and aleurone tissues during germination. Suppression of both genes in barley RNA interference (RNAi) lines indicated roles in metabolism of 2,4-dichlorophenoxybutyrate (2,4-DB) and indole butyric acid (IBA), jasmonate biosynthesis, and determination of grain size. Transformation of the Arabidopsis cts-1 null mutant with HvABCD1 and HvABCD2 confirmed these findings. HvABCD2 partially or completely complemented all tested phenotypes of cts-1. In contrast, HvABCD1 failed to complement the germination and establishment phenotypes of cts-1 but increased the sensitivity of hypocotyls to 100 μM IBA and partially complemented the seed size phenotype. HvABCD1 also partially complemented the yeast pxa1/pxa2Δ mutant for fatty acid β-oxidation. It is concluded that the core biochemical functions of peroxisomal ABC transporters are largely conserved between oilseeds and cereals but that their physiological roles and importance may differ. PMID:24913629

  14. 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.

  15. Origin of Multiple Peaks in the Potentiodynamic Oxidation of CO Adlayers on Pt and Ru-Modified Pt Electrodes.

    PubMed

    Wang, Hongsen; Abruña, Héctor D

    2015-05-21

    The study of the electrooxidation mechanism of CO(ad) on Pt based catalysts is very important for designing more effective CO-tolerant electrocatalysts for fuel cells. We have studied the origin of multiple peaks in the cyclic voltammograms of CO stripping from polycrystalline Pt and Ru modified polycrystalline Pt (Pt/Ru) surfaces in both acidic and alkaline media by differential electrochemical mass spectrometry (DEMS), DFT calculations, and kinetic Monte Carlo (KMC) simulations. A new CO(ad) electrooxidation kinetic model on heterogeneous Pt and Pt/Ru catalysts is proposed to account for the multiple peaks experimentally observed. In this model, OH species prefer to adsorb at low-coordination sites or Ru sites and, thus, suppress CO repopulation from high-coordination sites onto these sites. Therefore, CO(ad) oxidation occurs on different facets or regions, leading to multiplicity of CO stripping peaks. This work provides a new insight into the CO electrooxidation mechanism and kinetics on heterogeneous catalysts.

  16. Optimal control of the electronic current density: Application to one- and two-dimensional one-electron systems

    SciTech Connect

    Kammerlander, David; Marques, Miguel A. L.; Castro, Alberto

    2011-04-15

    Quantum optimal control theory is a powerful tool for engineering quantum systems subject to external fields such as the ones created by intense lasers. The formulation relies on a suitable definition for a target functional, that translates the intended physical objective to a mathematical form. We propose the use of target functionals defined in terms of the one-particle density and its current. A strong motivation for this is the possibility of using time-dependent density-functional theory for the description of the system dynamics. We exemplify this idea by defining an objective functional that on one hand attempts a large overlap with a target density and on the other hand minimizes the current. The latter requirement leads to optimized states with increased stability, which we prove with a few examples of one- and two-dimensional one-electron systems.

  17. Trimer effects in fragment molecular orbital-linear combination of molecular orbitals calculation of one-electron orbitals for biomolecules.

    PubMed

    Kobori, Tomoki; Sodeyama, Keitaro; Otsuka, Takao; Tateyama, Yoshitaka; Tsuneyuki, Shinji

    2013-09-07

    The fragment molecular orbital (FMO)-linear combination of molecular orbitals (LCMO) method incorporates as an efficient post-process calculation of one-electron orbitals of the whole system after the FMO total energy calculation. A straightforward way to increase the accuracy is inclusion of the trimer effect. Here, we derive a comprehensive formulation called the FMO3-LCMO method. To keep the computational costs of the trimer term low enough, we use a matrix-size reduction technique. We evaluated the accuracy and efficiency of the FMO3-LCMO scheme in model biological systems (alanine oligomer and chignolin). The results show that delocalized electronic orbitals with covalent and hydrogen bonds are better described at the trimer level, and the FMO3-LCMO method is applicable to quantitative evaluations of a wide range of frontier orbitals in large biosystems.

  18. Theoretical study of the protonation of the one-electron-reduced guanine-cytosine base pair by water.

    PubMed

    Hsu, Sodio C N; Wang, Tzu-Pin; Kao, Chai-Lin; Chen, Hui-Fen; Yang, Po-Yu; Chen, Hsing-Yin

    2013-02-21

    Prototropic equilibria in ionized DNA play an important role in charge transport and radiation damage of DNA and, therefore, continue to attract considerable attention. Although it is well-established that electron attachment will induce an interbase proton transfer from N1 of guanine (G) to N3 of cytosine (C), the question of whether the surrounding water in the major and minor grooves can protonate the one-electron-reduced G:C base pair still remains open. In this work, density functional theory (DFT) calculations were employed to investigate the energetics and mechanism for the protonation of the one-electron-reduced G:C base pair by water. Through the calculations of thermochemical cycles, the protonation free energies were estimated to be in the range of 11.6-14.2 kcal/mol. The calculations for the models of C(•-)(H(2)O)(8) and G(-H1)(-)(H(2)O)(16), which were used to simulate the detailed processes of protonation by water before and after the interbase proton transfer, respectively, revealed that the protonation proceeds through a concerted double proton transfer involving the water molecules in the first and second hydration shells. Comparing the present results with the rates of interbase proton transfer and charge transfer along DNA suggests that protonation on the C(•-) moiety is not competitive with interbase proton transfer, but the possibility of protonation on the G(-H1)(-) moiety after interbase proton transfer cannot be excluded. Electronic-excited-state calculations were also carried out by the time-dependent DFT approach. This information is valuable for experimental identification in the future.

  19. Multiple Supersonic Phase Fronts Launched at a Complex-Oxide Heterointerface

    NASA Astrophysics Data System (ADS)

    Först, M.; Beyerlein, K. R.; Mankowsky, R.; Hu, W.; Mattoni, G.; Catalano, S.; Gibert, M.; Yefanov, O.; Clark, J. N.; Frano, A.; Glownia, J. M.; Chollet, M.; Lemke, H.; Moser, B.; Collins, S. P.; Dhesi, S. S.; Caviglia, A. D.; Triscone, J.-M.; Cavalleri, A.

    2017-01-01

    Selective optical excitation of a substrate lattice can drive phase changes across heterointerfaces. This phenomenon is a nonequilibrium analogue of static strain control in heterostructures and may lead to new applications in optically controlled phase change devices. Here, we make use of time-resolved nonresonant and resonant x-ray diffraction to clarify the underlying physics and to separate different microscopic degrees of freedom in space and time. We measure the dynamics of the lattice and that of the charge disproportionation in NdNiO3 , when an insulator-metal transition is driven by coherent lattice distortions in the LaAlO3 substrate. We find that charge redistribution propagates at supersonic speeds from the interface into the NdNiO3 film, followed by a sonic lattice wave. When combined with measurements of magnetic disordering and of the metal-insulator transition, these results establish a hierarchy of events for ultrafast control at complex-oxide heterointerfaces.

  20. Catalytic oxidation of dye waste water by biomass charcoal loaded multiple rare earth composite material

    NASA Astrophysics Data System (ADS)

    Suriga; CHEN, Liping

    2017-01-01

    The main purpose of this study is to investigate the individual effect as well as the interactions of different influencing factors like catalyst dosage, aeration rate, temperature and pH on the removal of methylene blue (MB) using biomass charcoal loaded multiple rare earth composite material. Design-Expert 7.0 was used to design testing program and establish response surface model. The result showed that among the factors, catalyst dosage played the most important role, then pH value, aeration rate and temperature in turn. By the optimization of process parameters, the optimum experimental conditions were catalyst dosage of 2.50 g, aeration rate of 2.5 L·min-1, temperature of 21 °C and pH value of 12, under these optimum conditions, maximum predicted and observed decolorization rate were 100.00% and 99.61%, the observed value was well match with the predicted value.

  1. Self-interaction correction in multiple scattering theory: application to transition metal oxides

    SciTech Connect

    Daene, Markus W; Lueders, Martin; Ernst, Arthur; Diemo, Koedderitzsch; Temmerman, Walter M; Szotek, Zdzislawa; Wolfam, Hergert

    2009-01-01

    We apply to transition metal monoxides the self-interaction corrected (SIC) local spin density (LSD) approximation, implemented locally in the multiple scattering theory within the Korringa-Kohn-Rostoker (KKR) band structure method. The calculated electronic structure and in particular magnetic moments and energy gaps are discussed in reference to the earlier SIC results obtained within the LMTO-ASA band structure method, involving transformations between Bloch and Wannier representations to solve the eigenvalue problem and calculate the SIC charge and potential. Since the KKR can be easily extended to treat disordered alloys, by invoking the coherent potential approximation (CPA), in this paper we compare the CPA approach and supercell calculations to study the electronic structure of NiO with cation vacancies.

  2. New Insights into the Role of Oxidative Stress Mechanisms in the Pathophysiology and Treatment of Multiple Sclerosis.

    PubMed

    Adamczyk, Bożena; Adamczyk-Sowa, Monika

    2016-01-01

    Multiple sclerosis (MS) is a multifactorial disease of the central nervous system (CNS) characterized by an inflammatory process and demyelination. The etiology of the disease is still not fully understood. Therefore, finding new etiological factors is of such crucial importance. It is suspected that the development of MS may be affected by oxidative stress (OS). In the acute phase OS initiates inflammatory processes and in the chronic phase it sustains neurodegeneration. Redox processes in MS are associated with mitochondrial dysfunction, dysregulation of axonal bioenergetics, iron accumulation in the brain, impaired oxidant/antioxidant balance, and OS memory. The present paper is a review of the current literature about the role of OS in MS and it focuses on all major aspects. The article explains the mechanisms of OS, reports unique biomarkers with regard to their clinical significance, and presents a poorly understood relationship between OS and neurodegeneration. It also provides novel methods of treatment, including the use of antioxidants and the role of antioxidants in neuroprotection. Furthermore, adding new drugs in the treatment of relapse may be useful. The article considers the significance of OS in the current treatment of MS patients.

  3. New Insights into the Role of Oxidative Stress Mechanisms in the Pathophysiology and Treatment of Multiple Sclerosis

    PubMed Central

    Adamczyk-Sowa, Monika

    2016-01-01

    Multiple sclerosis (MS) is a multifactorial disease of the central nervous system (CNS) characterized by an inflammatory process and demyelination. The etiology of the disease is still not fully understood. Therefore, finding new etiological factors is of such crucial importance. It is suspected that the development of MS may be affected by oxidative stress (OS). In the acute phase OS initiates inflammatory processes and in the chronic phase it sustains neurodegeneration. Redox processes in MS are associated with mitochondrial dysfunction, dysregulation of axonal bioenergetics, iron accumulation in the brain, impaired oxidant/antioxidant balance, and OS memory. The present paper is a review of the current literature about the role of OS in MS and it focuses on all major aspects. The article explains the mechanisms of OS, reports unique biomarkers with regard to their clinical significance, and presents a poorly understood relationship between OS and neurodegeneration. It also provides novel methods of treatment, including the use of antioxidants and the role of antioxidants in neuroprotection. Furthermore, adding new drugs in the treatment of relapse may be useful. The article considers the significance of OS in the current treatment of MS patients. PMID:27829982

  4. HDL inhibits the effects of oxidized phospholipids on endothelial cell gene expression via multiple mechanisms[S

    PubMed Central

    Emert, Benjamin; Hasin-Brumshtein, Yehudit; Springstead, James R.; Vakili, Ladan; Berliner, Judith A.; Lusis, Aldons J.

    2014-01-01

    Oxidized 1-palmitoyl-2-arachidonyl-sn-glycero-3-phospholcholine (OxPAPC) and its component phospholipids accumulate in atherosclerotic lesions and regulate the expression of >1,000 genes, many proatherogenic, in human aortic endothelial cells (HAECs). In contrast, there is evidence in the literature that HDL protects the vasculature from inflammatory insult. We have previously shown that in HAECs, HDL attenuates the expression of several proatherogenic genes regulated by OxPAPC and 1-palmitoyl-2-(5,6-epoxyisoprostane E2)-sn-glycero-3-phosphocholine. We now demonstrate that HDL reverses >50% of the OxPAPC transcriptional response. Genes reversed by HDL are enriched for inflammatory and vascular development pathways, while genes not affected by HDL are enriched for oxidative stress response pathways. The protective effect of HDL is partially mimicked by cholesterol repletion and treatment with apoA1 but does not require signaling through scavenger receptor class B type I. Furthermore, our data demonstrate that HDL protection requires direct interaction with OxPAPC. HDL-associated platelet-activating factor acetylhydrolase (PAF-AH) hydrolyzes short-chain bioactive phospholipids in OxPAPC; however, inhibiting PAF-AH activity does not prevent HDL protection. Our results are consistent with HDL sequestering specific bioactive lipids in OxPAPC, thereby preventing their regulation of select target genes. Overall, this work implicates HDL as a major regulator of OxPAPC action in endothelial cells via multiple mechanisms. PMID:24859737

  5. Investigation of hair dye deposition, hair color loss, and hair damage during multiple oxidative dyeing and shampooing cycles.

    PubMed

    Zhang, Guojin; McMullen, Roger L; Kulcsar, Lidia

    2016-01-01

    Color fastness is a major concern for consumers and manufacturers of oxidative hair dye products. Hair dye loss results from multiple wash cycles in which the hair dye is dissolved by water and leaches from the hair shaft. In this study, we carried out a series of measurements to help us better understand the kinetics of the leaching process and pathways associated with its escape from the fiber. Hair dye leaching kinetics was measured by suspending hair in a dissolution apparatus and monitoring the dye concentration in solution (leached dye) with an ultraviolet-visible spectrophotometer. The physical state of dye deposited in hair fibers was evaluated by a reflectance light microscopy technique, based on image stacking, allowing enhanced depth of field imaging. The dye distribution within the fiber was monitored by infrared spectroscopic imaging of hair fiber cross sections. Damage to the ultrafine structure of the hair cuticle (surface, endocuticle, and cell membrane complex) and cortex (cell membrane complex) was determined in hair cross sections and on the hair fiber surface with atomic force microscopy. Using differential scanning calorimetry, we investigated how consecutive coloring and leaching processes affect the internal proteins of hair. Further, to probe the surface properties of hair we utilized contact angle measurements. This study was conducted on both pigmented and nonpigmented hair to gain insight into the influence of melanin on the hair dye deposition and leaching processes. Both types of hair were colored utilizing a commercial oxidative hair dye product based on pyrazole chemistry.

  6. Cellular consequences of oxidative stress in riboflavin responsive multiple acyl-CoA dehydrogenation deficiency patient fibroblasts.

    PubMed

    Cornelius, Nanna; Corydon, Thomas J; Gregersen, Niels; Olsen, Rikke K J

    2014-08-15

    Mitochondrial dysfunction and oxidative stress are central to the molecular pathology of many human diseases. Riboflavin responsive multiple acyl-CoA dehydrogenation deficiency (RR-MADD) is in most cases caused by variations in the gene coding for electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO). Currently, patients with RR-MADD are treated with high doses of riboflavin resulting in improvements of the clinical and biochemical profiles. However, in our recent studies of RR-MADD, we have shown that riboflavin treatment cannot fully correct the molecular defect in patient cells producing increased reactive oxygen species (ROS). In the current study, we aim to elucidate the cellular consequences of increased ROS by studying the cellular ROS adaption systems including antioxidant system, mitochondrial dynamics and metabolic reprogramming. We have included fibroblasts from six unrelated RR-MADD patients and two control fibroblasts cultivated under supplemented and depleted riboflavin conditions and with coenzyme Q10 (CoQ10) treatment. We demonstrated inhibition of mitochondrial fusion with increased fractionation and mitophagy in the patient fibroblasts. Furthermore, we indicated a shift in the energy metabolism by decreased protein levels of SIRT3 and decreased expression of fatty acid β-oxidation enzymes in the patient fibroblasts. Finally, we showed that CoQ10 treatment has a positive effect on the mitochondrial dynamic in the patient fibroblasts, indicated by increased mitochondrial fusion marker and reduced mitophagy. In conclusion, our results indicate that RR-MADD patient fibroblasts suffer from a general mitochondria dysfunction, probably initiated as a rescue mechanism for the patient cells to escape apoptosis as a result of the oxidative stress. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Is warmer better? Decreased oxidative damage in notothenioid fish after long-term acclimation to multiple stressors.

    PubMed

    Enzor, Laura A; Place, Sean P

    2014-09-15

    Antarctic fish of the suborder Notothenioidei have evolved several unique adaptations to deal with subzero temperatures. However, these adaptations may come with physiological trade-offs, such as an increased susceptibility to oxidative damage. As such, the expected environmental perturbations brought on by global climate change have the potential to significantly increase the level of oxidative stress and cellular damage in these endemic fish. Previous single stressor studies of the notothenioids have shown they possess the capacity to acclimate to increased temperatures, but the cellular-level effects remain largely unknown. Additionally, there is little information on the ability of Antarctic fish to respond to ecologically relevant environmental changes where multiple variables change concomitantly. We have examined the potential synergistic effects that increased temperature and Ṗ(CO2) have on the level of protein damage in Trematomus bernacchii, Pagothenia borchgrevinki and Trematomus newnesi, and combined these measurements with changes in total enzymatic activity of catalase (CAT) and superoxide dismutase (SOD) in order to gauge tissue-specific changes in antioxidant capacity. Our findings indicate that total SOD and CAT activity levels displayed only small changes across treatments and tissues. Short-term acclimation to decreased seawater pH and increased temperature resulted in significant increases in oxidative damage. Surprisingly, despite no significant change in antioxidant capacity, cellular damage returned to near-basal levels, and significantly decreased in T. bernacchii, after long-term acclimation. Overall, these data suggest that notothenioid fish currently maintain the antioxidant capacity necessary to offset predicted future ocean conditions, but it remains unclear whether this capacity comes with physiological trade-offs.

  8. Effect of multiple cytokines plus bacterial endotoxin on glucose and nitric oxide production by cultured hepatocytes.

    PubMed

    Ceppi, E D; Smith, F S; Titheradge, M A

    1996-07-15

    Treatment of cultured hepatocytes with a combination of cytokines, including tumour necrosis factor-alpha, interferon-gamma and interleukin-1 beta, plus lipopolysaccharide resulted in a time-dependent induction of nitric oxide (NO) synthase (as measured by NO2- (+) NO3- production) and inhibition of hepatic gluconeogenesis and glycogen breakdown. The inhibition of glucose release was comparable with the observed following treatment of rats with lipopolysaccharide or treatment of isolated hepatocytes with artificial NO donors. In addition, this effect was also evident with all substrates tested that enter the gluconeogenic pathway below the level of phosphoenolpyruvate carboxykinase, suggesting that this combination of cytokines may underlie the inhibition of gluconeogenesis observed in endotoxic shock. The maximal inhibition of glucose output required the presence of all the cytokines plus lipopolysaccharide, whereas the induction of NO synthase was independent of the lipopolysaccharide when the cytokines were employed. Inclusion of interferon-gamma was essential to obtain a maximal response for either parameter. Inclusion of 1 mM N(G)-monomethyl-L-arginine in the incubation abolished the increase in NO2- (+) NO3- observed with the complete cytokine mixture and various combinations; however, it failed to prevent the inhibition in glucose output, indicating that mechanisms other than NO underlie the cytokine-induced inhibition of glucose release.

  9. Multiple Supersonic Phase Fronts Launched at a Complex-Oxide Heterointerface

    DOE PAGES

    Först, M.; Beyerlein, K. R.; Mankowsky, R.; ...

    2017-01-09

    Selective optical excitation of a substrate lattice can drive phase changes across heterointerfaces. This phenomenon is a nonequilibrium analogue of static strain control in heterostructures and may lead to new applications in optically controlled phase change devices. Here, we make use of time-resolved nonresonant and resonant x-ray diffraction to clarify the underlying physics and to separate different microscopic degrees of freedom in space and time. We also measure the dynamics of the lattice and that of the charge disproportionation in NdNiO 3 , when an insulator-metal transition is driven by coherent lattice distortions in the LaAlO 3 substrate. We findmore » that charge redistribution propagates at supersonic speeds from the interface into the NdNiO 3 film, followed by a sonic lattice wave. Our results establish a hierarchy of events for ultrafast control at complex-oxide heterointerfaces, when combined with measurements of magnetic disordering and of the metal-insulator transition.« less

  10. Nitrogen loading and nitrous oxide emissions from a river with multiple hydroelectric reservoirs.

    PubMed

    Chen, Jinsong; Cao, Wenzhi; Cao, Di; Huang, Zheng; Liang, Ying

    2015-05-01

    River networks receive a large fraction of the anthropogenic nitrogen applied to river catchments. The different impacts of the stream nitrogen (N) loading on nitrous oxide (N2O) emissions from various of aquatic ecosystems are still unknown. In this study, direct measurements of water-air interface N2O exchange in different water bodies were conducted. Results showed that the water-air interface N2O exchange from tributaries, hydropower station reservoirs, a main stream, and its estuary were 10.14 ± 13.51, 15.64 ± 10.72, 27.59 ± 20.99, and 15.98 ± 12.26 µg N2O-N m(-2) h(-1), respectively, indicating the strong impacts of human activities on N2O emission rates. The water NO2 (-)-N values predicted the dissolved N2O concentrations better than did the NO3 (-)-N and NH4 (+)-N values, indicating strong denitrification and nitrification processes. The dissolved inorganic N explained 36 % of the variations in the N2O emissions for the whole river network.

  11. Multiple archaeal groups mediate methane oxidation in anoxic cold seep sediments.

    PubMed

    Orphan, Victoria J; House, Christopher H; Hinrichs, Kai-Uwe; McKeegan, Kevin D; DeLong, Edward F

    2002-05-28

    No microorganism capable of anaerobic growth on methane as the sole carbon source has yet been cultivated. Consequently, information about these microbes has been inferred from geochemical and microbiological observations of field samples. Stable isotope analysis of lipid biomarkers and rRNA gene surveys have implicated specific microbes in the anaerobic oxidation of methane (AOM). Here we use combined fluorescent in situ hybridization and secondary ion mass spectrometry analyses, to identify anaerobic methanotrophs in marine methane-seep sediments. The results provide direct evidence for the involvement of at least two distinct archaeal groups (ANME-1 and ANME-2) in AOM at methane seeps. Although both archaeal groups often occurred in direct physical association with bacteria, they also were observed as monospecific aggregations and as single cells. The ANME-1 archaeal group more frequently existed in monospecific aggregations or as single filaments, apparently without a bacterial partner. Bacteria associated with both archaeal groups included, but were not limited to, close relatives of Desulfosarcina species. Isotopic analyses suggest that monospecific archaeal cells and cell aggregates were active in anaerobic methanotrophy, as were multispecies consortia. In total, the data indicate that the microbial species and biotic interactions mediating anaerobic methanotrophy are diverse and complex. The data also clearly show that highly structured ANME-2/Desulfosarcina consortia are not the sole entities responsible for AOM at marine methane seeps. Other microbial groups, including ANME-1 archaea, are capable of anaerobic methane consumption either as single cells, in monospecific aggregates, or in multispecies consortia.

  12. Striking multiple synergies created by combining reduced graphene oxides and carbon nanotubes for polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Song, Ping'an; Liu, Lina; Fu, Shenyuan; Yu, Youming; Jin, Chunde; Wu, Qiang; Zhang, Yan; Li, Qian

    2013-03-01

    The extraordinary properties of carbon nanotubes (CNTs) and graphene stimulate the development of advanced composites. Recently, several studies have reported significant synergies in the mechanical, electrical and thermal conductivity properties of polymer nanocomposites by incorporating their nanohybrids. In this work, we created polypropylene nanocomposites with homogeneous dispersion of CNTs and reduced graphene oxides via a facile polymer-latex-coating plus melt-mixing strategy, and investigated their synergistic effects in their viscoelastic, gas barrier, and flammability properties. Interestingly, the results show remarkable synergies, enhancing their melt modulus and viscosity, O2 barrier, and flame retardancy properties and respectively exhibiting a synergy percentage of 15.9%, 45.3%, and 20.3%. As previously reported, we also observed remarkable synergistic effects in their tensile strength (14.3%) and Young’s modulus (27.1%), electrical conductivity (32.3%) and thermal conductivity (34.6%). These impressive results clearly point towards a new strategy to create advanced materials by adding binary combinations of different types of nanofillers.

  13. A multiple shock tube and chemical kinetic modeling study of diethyl ether pyrolysis and oxidation.

    PubMed

    Yasunaga, K; Gillespie, F; Simmie, J M; Curran, H J; Kuraguchi, Y; Hoshikawa, H; Yamane, M; Hidaka, Y

    2010-09-02

    The pyrolysis and oxidation of diethyl ether (DEE) has been studied at pressures from 1 to 4 atm and temperatures of 900-1900 K behind reflected shock waves. A variety of spectroscopic diagnostics have been used, including time-resolved infrared absorption at 3.39 mum and time-resolved ultraviolet emission at 431 nm and absorption at 306.7 nm. In addition, a single-pulse shock tube was used to measure reactant, intermediate, and product species profiles by GC samplings at different reaction times varying from 1.2 to 1.8 ms. A detailed chemical kinetic model comprising 751 reactions involving 148 species was assembled and tested against the experiments with generally good agreement. In the early stages of reaction the unimolecular decomposition and hydrogen atom abstraction of DEE and the decomposition of the ethoxy radical have the largest influence. In separate experiments at 1.9 atm and 1340 K, it is shown that DEE inhibits the reactivity of an equimolar mixture of hydrogen and oxygen (1% of each).

  14. Effects of nitric oxide on magnocellular neurons of the supraoptic nucleus involve multiple mechanisms

    PubMed Central

    da Silva, M.P.; Cedraz-Mercez, P.L.; Varanda, W.A.

    2014-01-01

    Physiological evidence indicates that the supraoptic nucleus (SON) is an important region for integrating information related to homeostasis of body fluids. Located bilaterally to the optic chiasm, this nucleus is composed of magnocellular neurosecretory cells (MNCs) responsible for the synthesis and release of vasopressin and oxytocin to the neurohypophysis. At the cellular level, the control of vasopressin and oxytocin release is directly linked to the firing frequency of MNCs. In general, we can say that the excitability of these cells can be controlled via two distinct mechanisms: 1) the intrinsic membrane properties of the MNCs themselves and 2) synaptic input from circumventricular organs that contain osmosensitive neurons. It has also been demonstrated that MNCs are sensitive to osmotic stimuli in the physiological range. Therefore, the study of their intrinsic membrane properties became imperative to explain the osmosensitivity of MNCs. In addition to this, the discovery that several neurotransmitters and neuropeptides can modulate their electrical activity greatly increased our knowledge about the role played by the MNCs in fluid homeostasis. In particular, nitric oxide (NO) may be an important player in fluid balance homeostasis, because it has been demonstrated that the enzyme responsible for its production has an increased activity following a hypertonic stimulation of the system. At the cellular level, NO has been shown to change the electrical excitability of MNCs. Therefore, in this review, we focus on some important points concerning nitrergic modulation of the neuroendocrine system, particularly the effects of NO on the SON. PMID:24519124

  15. The effect of albedo neutrons on the neutron multiplication of small plutonium oxide samples in a PNCC chamber

    NASA Astrophysics Data System (ADS)

    Bourva, L. C.-A.; Croft, S.; Weaver, D. R.

    2002-03-01

    This paper describes how to evaluate the effect of neutrons reflected from parts of a passive neutron coincidence chamber on the neutron leakage self-multiplication, ML, of a fissile sample. It is shown that albedo neutrons contribute, in the case of small plutonium bearing samples, to a significant part of ML, and that their effect has to be taken into account in the relationship between the measured coincidence count rates and the 240Pu effective mass of the sample. A simple one-interaction model has been used to write the balance of neutron gains and losses in the material when exposed to the re-entrant neutron flux. The energy and intensity profiles of the re-entrant flux have been parameterised using Monte Carlo MCNP TM calculations. This technique has been implemented for the On Site Laboratory neutron/gamma counter within the existing MEPL 1.0 code for the determination of the neutron leakage self-multiplication. Benchmark tests of the resulting MEPL 2.0 code with MCNP TM calculations showed that for typical safeguard samples the newly developed code estimates ( ML-1) to within 1% of the MCNP TM results. The precision of these results along with the rapidity of the proposed calculation method therefore make the use of a "known ML" approach for solving the Böhnel equations very attractive when measuring density controlled gram size PuO 2 or Mixed Oxide (MOX) samples.

  16. Electrical properties of single and multiple poly(3,4-ethylenedioxythiophene) nanowires for sensing nitric oxide gas.

    PubMed

    Lu, Hui-Hsin; Lin, Chia-Yu; Hsiao, Tzu-Chien; Fang, Yueh-Yuan; Ho, Kuo-Chuan; Yang, Dongfang; Lee, Chih-Kung; Hsu, Su-Ming; Lin, Chii-Wann

    2009-04-27

    The electrical properties of conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), nanowires were studied to develop nitric oxide (NO) gas sensors with low working temperatures. A nanowire with a diameter of 300 nm was fabricated using dip-pen nanolithography (DPN) across a 55 microm gap between a pair of electrodes. The electrical properties of single or multiple PEDOT nanowires were examined by plotting the current-voltage (I-V) curves in the range -3 V to +3 V at temperatures between 298 K and 393 K. The conductance of parallel wires was normalized with respect to the dimensions of the fabricated nanowires. The single nanowire exhibited nonlinear conductance associated with hysteresis but multiple wires did not. The currents increased with the temperature and the I-V characteristics were consistent with the power law G(T)alphaT(alpha) with alpha approximately 5.14 and 5.43. The responses to NO were highly linear and reproducible, indicating that sensing using PEDOT nanowires was reliable with a minimal concentration of NO of 10 ppm.

  17. [Multiplication of Brucella abortus and production of nitric oxide in two macrophage cell lines of different origin].

    PubMed

    Serafino, J; Conde, S; Zabal, O; Samartino, L

    2007-01-01

    Brucella abortus is a bacterium which causes abortions and infertility in cattle and undulant fever in humans. It multiplies intracellularly, evading the mechanisms of cellular death. Nitric oxide (NO) is important in the regulation of the immune response. In the present work, we studied the ability of three B. abortus strains to survive intracellularly in two macrophage cell lines. The bacterial multiplication in both cell lines was determined at two different times in UFC/ ml units. Moreover the inoculated cells were also observed under light-field and fluorescence microscopy stained with Giemsa and acridine orange, respectively. The stain of both cellular lines showed similar results with respect to the UFC/ml determination. The presence of B. abortus was confirmed by electronic microscopy. In both macrophage cell lines inoculated with the rough strain RB51, the multiplication diminished and the level of NO was higher, compared with cells inoculated with smooth strains (S19 and 2308). These results suggest that the absence of O-chain of LPS probably affects the intracellular growth of B. abortus.

  18. Using multiple hydrogen bonding cross-linkers to access reversibly responsive three dimensional graphene oxide architecture

    NASA Astrophysics Data System (ADS)

    Han, Junkai; Shen, Yongtao; Feng, Wei

    2016-07-01

    Three-dimensional (3D) graphene materials have attracted a lot of attention for efficiently utilizing inherent properties of graphene sheets. However, 3D graphene materials reported in the previous literature are constructed through covalent or weak non-covalent interactions, causing permanent structure/property changes. In this paper, a novel 3D graphene material of dynamic interactions between lamellas with 2-ureido-4[1H]-pyrimidinone as a supra-molecular motif has been synthesized. This 3D graphene material shows enhanced sheet interactions while the cross-linking takes place. With proper solvent stimulation, the integrated 3D graphene material can disassemble as isolated sheets. The driving force for the 3D structure assembly or disassembly is considered to be the forming or breaking of the multiple hydrogen bonding pairs. Furthermore, the 3D material is used as an intelligent dye adsorber to adsorb methylene blue and release it. The controllable and reversible characteristic of this 3D graphene material may open an avenue to the synthesis and application of novel intelligent materials.Three-dimensional (3D) graphene materials have attracted a lot of attention for efficiently utilizing inherent properties of graphene sheets. However, 3D graphene materials reported in the previous literature are constructed through covalent or weak non-covalent interactions, causing permanent structure/property changes. In this paper, a novel 3D graphene material of dynamic interactions between lamellas with 2-ureido-4[1H]-pyrimidinone as a supra-molecular motif has been synthesized. This 3D graphene material shows enhanced sheet interactions while the cross-linking takes place. With proper solvent stimulation, the integrated 3D graphene material can disassemble as isolated sheets. The driving force for the 3D structure assembly or disassembly is considered to be the forming or breaking of the multiple hydrogen bonding pairs. Furthermore, the 3D material is used as an

  19. Oxidative Stress Triggers Body-Wide Skipping of Multiple Exons of the Spinal Muscular Atrophy Gene

    PubMed Central

    Seo, Joonbae; Singh, Natalia N.; Ottesen, Eric W.; Sivanesan, Senthilkumar; Shishimorova, Maria; Singh, Ravindra N.

    2016-01-01

    Humans carry two nearly identical copies of Survival Motor Neuron gene: SMN1 and SMN2. Loss of SMN1 leads to spinal muscular atrophy (SMA), the most frequent genetic cause of infant mortality. While SMN2 cannot compensate for the loss of SMN1 due to predominant skipping of exon 7, correction of SMN2 exon 7 splicing holds the promise of a cure for SMA. Previously, we used cell-based models coupled with a multi-exon-skipping detection assay (MESDA) to demonstrate the vulnerability of SMN2 exons to aberrant splicing under the conditions of oxidative stress (OS). Here we employ a transgenic mouse model and MESDA to examine the OS-induced splicing regulation of SMN2 exons. We induced OS using paraquat that is known to trigger production of reactive oxygen species and cause mitochondrial dysfunction. We show an overwhelming co-skipping of SMN2 exon 5 and exon 7 under OS in all tissues except testis. We also show that OS increases skipping of SMN2 exon 3 in all tissues except testis. We uncover several new SMN2 splice isoforms expressed at elevated levels under the conditions of OS. We analyze cis-elements and transacting factors to demonstrate the diversity of mechanisms for splicing misregulation under OS. Our results of proteome analysis reveal downregulation of hnRNP H as one of the potential consequences of OS in brain. Our findings suggest SMN2 as a sensor of OS with implications to SMA and other diseases impacted by low levels of SMN protein. PMID:27111068

  20. Nitric Oxide Mediated Transcriptome Profiling Reveals Activation of Multiple Regulatory Pathways in Arabidopsis thaliana

    PubMed Central

    Hussain, Adil; Mun, Bong-Gyu; Imran, Qari M.; Lee, Sang-Uk; Adamu, Teferi A.; Shahid, Muhammad; Kim, Kyung-Min; Yun, Byung-Wook

    2016-01-01

    Imbalance between the accumulation and removal of nitric oxide and its derivatives is a challenge faced by all plants at the cellular level, and is especially important under stress conditions. Exposure of plants to various biotic and abiotic stresses causes rapid changes in cellular redox tone potentiated by the rise in reactive nitrogen species that serve as signaling molecules in mediating defensive responses. To understand mechanisms mediated by these signaling molecules, we performed a large-scale analysis of the Arabidopsis transcriptome induced by nitrosative stress. We generated an average of 84 and 91 million reads from three replicates each of control and 1 mM S-nitrosocysteine (CysNO)-infiltrated Arabidopsis leaf samples, respectively. After alignment, more than 95% of all reads successfully mapped to the reference and 32,535 genes and 55,682 transcripts were obtained. CysNO infiltration caused differential expression of 6436 genes (3448 up-regulated and 2988 down-regulated) and 6214 transcripts (3335 up-regulated and 2879 down-regulated) 6 h post-infiltration. These differentially expressed genes were found to be involved in key physiological processes, including plant defense against various biotic and abiotic stresses, hormone signaling, and other developmental processes. After quantile normalization of the FPKM values followed by student's T-test (P < 0.05) we identified 1165 DEGs (463 up-regulated and 702 down-regulated) with at least 2-folds change in expression after CysNO treatment. Expression patterns of selected genes involved in various biological pathways were verified using quantitative real-time PCR. This study provides comprehensive information about plant responses to nitrosative stress at transcript level and would prove helpful in understanding and incorporating mechanisms associated with nitrosative stress responses in plants. PMID:27446194

  1. Accurate calculation of absolute one-electron redox potentials of some para-quinone derivatives in acetonitrile.

    PubMed

    Namazian, Mansoor; Coote, Michelle L

    2007-08-02

    Standard ab initio molecular orbital theory and density functional theory calculations have been used to calculate absolute one-electron reduction potentials of several para-quinones in acetonitrile. The high-level composite method of G3(MP2)-RAD is used for the gas-phase calculations and a continuum model of solvation, CPCM, has been employed to calculate solvation energies. To compare the theoretical reduction potentials with experiment, the reduction potentials relative to a standard calomel electrode (SCE) have also been calculated and compared to experimental values. The average error of the calculated reduction potentials using the proposed method is 0.07 V without any additional approximation. An ONIOM method in which the core is studied at G3(MP2)-RAD and the substituent effect of the rest of the molecule is studied at R(O)MP2/6-311+G(3df,2p) provides an accurate low-cost alternative to G3(MP2)-RAD for larger molecules.

  2. A simple quasi-diabatization scheme suitable for spectroscopic problems based on one-electron properties of interacting states

    SciTech Connect

    Cave, Robert J.; Stanton, John F.

    2016-02-07

    We present a simple quasi-diabatization scheme applicable to spectroscopic studies that can be applied using any wavefunction for which one-electron properties and transition properties can be calculated. The method is based on rotation of a pair (or set) of adiabatic states to minimize the difference between the given transition property at a reference geometry of high symmetry (where the quasi-diabatic states and adiabatic states coincide) and points of lower symmetry where quasi-diabatic quantities are desired. Compared to other quasi-diabatization techniques, the method requires no special coding, facilitates direct comparison between quasi-diabatic quantities calculated using different types of wavefunctions, and is free of any selection of configurations in the definition of the quasi-diabatic states. On the other hand, the method appears to be sensitive to multi-state issues, unlike recent methods we have developed that use a configurational definition of quasi-diabatic states. Results are presented and compared with two other recently developed quasi-diabatization techniques.

  3. Electron-nuclear dynamics of the one-electron nonlinear polyatomic molecule H32+ in ultrashort intense laser pulses

    NASA Astrophysics Data System (ADS)

    Lefebvre, C.; Lu, H. Z.; Chelkowski, S.; Bandrauk, A. D.

    2014-02-01

    A quantum description of the one-electron triangular H32+ molecular ion, beyond the Born-Oppenheimer approximation, is used to study the full influence of the nuclear motion on the high-intensity photoionization and harmonic generation processes. A detailed analysis of electron and proton motions and their time-dependent acceleration allows for identification of the main electron recollision events as a function of time-dependent configuration of the protons. High-order-harmonic generation photons are shown to be produced by single-electron recollision in the second half of the pulse envelope, which also induces a redshift in the harmonics, due to the rapid few-femtosecond motions of protons. Perpendicular harmonics are produced, in general, with a linearly polarized laser pulse parallel to a bond of the triangular molecule, and, in particular, the harmonics in the cutoff region are elliptically polarized. When the laser-pulse polarization is parallel to a symmetry axis of the triangular molecular ion, creation and destruction of the chemical bond perpendicular to the polarization is predicted on a near-femtosecond time scale.

  4. Noise-assisted energy transfer from the dilation of the set of one-electron reduced density matrices

    NASA Astrophysics Data System (ADS)

    Chakraborty, Romit; Mazziotti, David A.

    2017-05-01

    Noise-assisted energy transfer can be explained geometrically in terms of the set of one-electron reduced density matrices (1-RDMs) [R. Chakraborty and D. A. Mazziotti, Phys. Rev. A 91, 010101(R) (2015)]. In this paper, we examine the geometric picture of quantum noise for the seven-chromophore Fenna-Matthews-Olson (FMO) complex. Noise expands the feasible set of orbital occupation trajectories to the target state through the violation of the pure-state N-representability conditions on the 1-RDM, known as the generalized Pauli constraints. While the generalized Pauli constraints are not explicitly known for seven-electron systems, we are able to treat a seven-exciton model of the FMO complex through the use of generalized Pauli constraints for p qubits which are known for arbitrary p. In the model, we find that while dephasing noise alone produces a trajectory of ensemble states that neither expands the set of 1-RDMs nor reaches the reaction center, the inclusion of both dephasing and dissipation expands the set of 1-RDMs and exhibits an efficient energy transfer to the reaction center. The degree to which the noise expands the set of 1-RDMs, violating the generalized Pauli constraints, is quantified by the distance of the 1-RDM outside its pure set to the distance of the 1-RDM inside its ensemble set. The geometric picture of energy transfer has applications to general quantum systems in chemistry and physics.

  5. Genetic, Immune-Inflammatory, and Oxidative Stress Biomarkers as Predictors for Disability and Disease Progression in Multiple Sclerosis.

    PubMed

    Kallaur, Ana Paula; Reiche, Edna Maria Vissoci; Oliveira, Sayonara Rangel; Simão, Andrea Name Colado; Pereira, Wildea Lice de Carvalho Jennings; Alfieri, Daniela Frizon; Flauzino, Tamires; Proença, Caio de Meleck; Lozovoy, Marcell Alysson Batisti; Kaimen-Maciel, Damacio Ramón; Maes, Michael

    2017-01-01

    The aim of this study was to evaluate the TNFβ NcoI polymorphism (rs909253) and immune-inflammatory, oxidative, and nitrosative stress (IO&NS) biomarkers as predictors of disease progression in multiple sclerosis (MS). We included 212 MS patients (150 female, 62 male, mean (±standard deviation (SD)) age = 42.7 ± 13.8 years) and 249 healthy controls (177 female, 72 male, 36.8 ± 11 years). The disability was measured the Expanded Disability Status Scale (EDSS) in 2006 and 2011. We determined the TNFβ NcoI polymorphism and serum levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, IL-4, IL-10, and IL-17, albumin, ferritin, and plasma levels of lipid hydroperoxides (CL-LOOH), carbonyl protein, advanced oxidation protein products (AOPPs), nitric oxide metabolites (NOx), and total radical-trapping antioxidant parameter (TRAP). The mean EDSS (±SD) in 2006 was 1.62 ± 2.01 and in 2011 3.16 ± 2.29, and disease duration was 7.34 ± 7.0 years. IL-10, TNF-α, IFN-γ, AOPP, and NOx levels were significantly higher and IL-4 lower in MS patients with a higher 2011 EDSS scores (≥3) as compared with those with EDSS < 3. The actual increases in EDSS from 2006 to 2011 were positively associated with TNF-α and IFN-γ. Increased IFN-γ values were associated with higher pyramidal symptoms and increased IL-6 with sensitive symptoms. Increased carbonyl protein and IL-10 but lowered albumin levels predicted cerebellar symptoms. The TNFB1/B2 genotype decreased risk towards progression of pyramidal symptoms. Treatments with IFN-β and glatiramer acetate significantly reduced TNF-α but did not affect the other IO&NS biomarkers or disease progression. Taken together, IO&NS biomarkers and NcoI TNFβ genotypes predict high disability in MS and are associated with different aspects of disease progression. New drugs to treat MS should also target oxidative stress pathways.

  6. Pulse-radiolysis studies on the interaction of one-electron-reduced species with ascorbate oxidase in aqueous solution.

    PubMed Central

    O'Neill, P; Fielden, E M; Finazzi-Agrò, A; Avigliano, L

    1983-01-01

    The interaction of e-aq., CO2-. and one-electron reduced nitroaromatics (RNO2-.) with ascorbate oxidase (AAO) was studied in aqueous solution at pH 6.0 and 7.5 by using the technique of pulse radiolysis. From observations at 330, 410 and 610 nm, interaction of e-aq. and CO2-. with AAO results in non-specific reduction of the protein followed by reduction of Type 1 Cu in a rate-determining intramolecular step. Only a few per cent of the reducing equivalents ultimately results in reduction of Type 1 Cu. With large excesses of reducing equivalents (e-aq. and CO2-.) with respect to the copper concentration, the amount of Type 1 copper reduced never exceeds 50% of the total amount of Type 1 copper after a single radiation pulse. With less-powerful reducing agents, e.g. RNO2-. reduction of Type 1 Cu occurs via a bimolecular step, and there is no evidence for formation of radicals on protein residues. From observations at 330 nm it is evident that Type 2 and/or Type 3 Cu may also be reduced along with Type 1 Cu. Almost stoichiometric reduction of AAO by RNO2-. was observed, e.g. the protein accepts 6-7 reducing equivalents. It is inferred that the various types of redox couples Cu2+/Cu+ are in equilibrium and that intramolecular electron transfer between the different types of Cu is not rate-determining when using RNO2-. as reducing agent. PMID:6405732

  7. Association analysis of nitric oxide synthases: NOS1, NOS2A and NOS3 genes, with multiple sclerosis.

    PubMed

    AlFadhli, Suad; Mohammed, Eiman M A; Al Shubaili, Asmahan

    2013-07-01

    Multiple sclerosis (MS) is a chronic inflammatory autoimmune disorder of the central nervous system. To explore the genetic basis of three nitric oxide synthase (NOS) genes: NOS1, NOS2A and NOS3, with susceptibility to MS. A total of 122 MS patients and 118 healthy controls screened for NOS1 (rs2682826, rs41279104), NOS2A (CCTTT)n/(TAAA)n and NOS3 (rs1800783, rs1800779, rs2070744, 27bpVNTR) markers, using TaqMan®SNP Genotyping Assays and fragment analysis were enrolled in this study. QRT-PCR and ELISA were used to analyse the expression of NOS3 mRNA and Nitric Oxide (NO) levels. Two NOS3 markers were associated with susceptibility to MS and early disease development. The NOS3 rs1800779 G-allele (p = 0.04) and GG-genotype (p = 0.02) showed association with susceptibility to MS. Short NOS2 (CCTTT)n (p = 0.03) and short/long repeat (p = 0.04) genotypes also showed associations with MS. These associations were intensified by sub-division of patients into Kuwaiti Arabs and Persians (p < 0.05). The NOS3-27 bp-VNTR a-allele was associated with early MS disease onset ≤26 years (p = 0.04). The NOS3-27 bp-VNTR a/b-genotype resulted in 23% lower NO production and the NOS3-rs1800779 AA-genotype resulted in lower NOS3 expression. Haplotypes obtained from NOS2A and NOS3 showed increased susceptibility to MS. NOS1 showed no significant association with MS. This study provides evidence for the association between selected NOS2 and NOS3 markers and MS susceptibility.

  8. Protein oxidation and peroxidation

    PubMed Central

    Davies, Michael J.

    2016-01-01

    Proteins are major targets for radicals and two-electron oxidants in biological systems due to their abundance and high rate constants for reaction. With highly reactive radicals damage occurs at multiple side-chain and backbone sites. Less reactive species show greater selectivity with regard to the residues targeted and their spatial location. Modification can result in increased side-chain hydrophilicity, side-chain and backbone fragmentation, aggregation via covalent cross-linking or hydrophobic interactions, protein unfolding and altered conformation, altered interactions with biological partners and modified turnover. In the presence of O2, high yields of peroxyl radicals and peroxides (protein peroxidation) are formed; the latter account for up to 70% of the initial oxidant flux. Protein peroxides can oxidize both proteins and other targets. One-electron reduction results in additional radicals and chain reactions with alcohols and carbonyls as major products; the latter are commonly used markers of protein damage. Direct oxidation of cysteine (and less commonly) methionine residues is a major reaction; this is typically faster than with H2O2, and results in altered protein activity and function. Unlike H2O2, which is rapidly removed by protective enzymes, protein peroxides are only slowly removed, and catabolism is a major fate. Although turnover of modified proteins by proteasomal and lysosomal enzymes, and other proteases (e.g. mitochondrial Lon), can be efficient, protein hydroperoxides inhibit these pathways and this may contribute to the accumulation of modified proteins in cells. Available evidence supports an association between protein oxidation and multiple human pathologies, but whether this link is causal remains to be established. PMID:27026395

  9. Modelling of CH4 multiple-reforming within the Ni-YSZ anode of a solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Tran, Dang Long; Tran, Quang Tuyen; Sakamoto, Mio; Sasaki, Kazunari; Shiratori, Yusuke

    2017-08-01

    A new approach for the modelling of the simultaneous dry and steam reforming of CH4 (methane multiple-reforming (MMR)) within the Ni-YSZ anode of a solid oxide fuel cell (SOFC) is introduced in this paper. MMR is modelled by using artificial neural network (ANN) and fuzzy inference system (FIS) that can express the gas composition and temperature dependences of the consumption or the production rate of gaseous species involved in MMR. The necessary parameters for this approach are determined from the measured reforming kinetics for an anode-supported cell (ASC) fuelled by a CH4-CO2-H2O-N2 mixture. The developed MMR model is incorporated into a 3D-CFD planar ASC model to calculate the SOFC performance, and the calculated results match well with experimental values for the feed of simulated biogas (CH4/CO2 = 1) and H2. The established SOFC model considering MMR is a powerful tool to simulate the performance of internal reforming SOFC.

  10. Oxidative responsiveness to multiple stressors in the key Antarctic species, Adamussium colbecki: Interactions between temperature, acidification and cadmium exposure.

    PubMed

    Benedetti, Maura; Lanzoni, Ilaria; Nardi, Alessandro; d'Errico, Giuseppe; Di Carlo, Marta; Fattorini, Daniele; Nigro, Marco; Regoli, Francesco

    2016-10-01

    High-latitude marine ecosystems are ranked to be among the most sensitive regions to climate change since highly stenothermal and specially adapted organisms might be seriously affected by global warming and ocean acidification. The present investigation was aimed to provide new insights on the sensitivity to such environmental stressors in the key Antarctic species, Adamussium colbecki, focussing also on their synergistic effects with cadmium exposure, naturally abundant in this area for upwelling phenomena. Scallops were exposed for 2 weeks to various combinations of Cd (0 and 40 μgL-1), pH (8.05 and 7.60) and temperature (-1 and +1 °C). Beside Cd bioaccumulation, a wide panel of early warning biomarkers were analysed in digestive glands and gills including levels of metallothioneins, individual antioxidants and total oxyradical scavenging capacity, onset of oxidative cell damage like lipid peroxidation, lysosomal stability, DNA integrity and peroxisomal proliferation. Results indicated reciprocal interactions between multiple stressors and their elaboration by a quantitative hazard model based on the relevance and magnitude of effects, highlighted a different sensitivity of analysed tissues. Due to cellular adaptations to high basal Cd content, digestive gland appeared more tolerant toward other prooxidant stressors, but sensitive to variations of the metal. On the other hand, gills were more affected by various combinations of stressors occurring at higher temperature.

  11. Impact of graphene oxide on the structure and function of important multiple blood components by a dose-dependent pattern.

    PubMed

    Feng, Ru; Yu, Yueping; Shen, Chaoxuan; Jiao, Yanpeng; Zhou, Changren

    2015-06-01

    Graphene and its derivatives have become great concern in biomedical fields. Though many investigations about their toxicity have been reported, systematic investigation on the interaction with multiple blood components is lacking. In this work, we studied the effects of the graphene oxide (GO) on the structure and function of the blood components, especially, on morphology and hemolysis of red blood cells (RBCs), bovine serum albumin (BSA) and fibrinogen conformation, complement activation, and blood coagulation function. Scanning electron microscopy observation and hemolysis test results showed that the GO can affect RBC morphology and membrane integrity in a concentration-dependent way. Fluorescence and circular dichroism spectra showed that GO could alter the secondary structures and conformation of BSA and fibrinogen. In addition, the presence of GO could also trigger complement activation by detecting their key biomarker molecules in plasma. In the blood clotting process, the GO showed significant adverse effect on the activated partial thromboplastin time but not on prothrombin time of the platelet-poor plasma. Meanwhile, the GO also caused abnormal thromboelastography parameters of the whole blood coagulation. The results obtained in this study provides good insight into understanding the biomedical application of GO in vivo. © 2014 Wiley Periodicals, Inc.

  12. A self-consistent, multi-variate method for the rapid determination of gas phase rate coefficients, applied to reactions of atmospheric VOC with multiple radical oxidants

    NASA Astrophysics Data System (ADS)

    Shaw, Jacob; Lidster, Richard; Cryer, Danny; Ramirez, Noelia; Whalley, Lisa; Rickard, Andrew; Evans, Mat; Dunmore, Rachel; Heard, Dwayne; Lewis, Ally; Carpenter, Lucy; Hamilton, Jacqui; Dillon, Terry

    2017-04-01

    Gas phase rate coefficients are fundamental to our understanding of atmospheric oxidation chemistry. However, experimentally determined data for the oxidation of thousands of VOC observed in the troposphere is not currently available. Here we present results obtained using a new experimental method that allows for the simultaneous study of multiple VOC reactions, in which each VOC is depleted relative to their oxidation rate coefficient. This technique builds on already established relative rate concepts but has the advantage of a significantly higher throughput of target VOC. Experiments are conducted across a wide range of VOC species, using different atmospheric radicals as oxidants. Where comparisons are possible, results are in satisfactory agreement with the literature allowing for the facile derivation of new rate coefficients for important atmospheric species.

  13. Efficacy of Fish Oil on Serum of TNFα, IL-1β, and IL-6 Oxidative Stress Markers in Multiple Sclerosis Treated with Interferon Beta-1b

    PubMed Central

    Ramirez-Ramirez, V.; Macias-Islas, M. A.; Ortiz, G. G.; Pacheco-Moises, F.; Torres-Sanchez, E. D.; Sorto-Gomez, T. E.; Cruz-Ramos, J. A.; Orozco-Aviña, G.; Celis de la Rosa, A. J.

    2013-01-01

    Multiple sclerosis (MS) is a chronic inflammatory disease, which leads to focal plaques of demyelination and tissue injury in the central nervous system. Oxidative stress is also thought to promote tissue damage in multiple sclerosis. Current research findings suggest that omega-3 polyunsaturated fatty acids (PUFAs) such as eicosapenta-enoic acid (EPA) and docosahexaenoic acid (DHA) contained in fish oil may have anti-inflammatory, antioxidant, and neuroprotective effects. The aim of the present work was to evaluate the efficacy of fish oil supplementation on serum proinflammatory cytokine levels, oxidative stress markers, and disease progression in MS. 50 patients with relapsing-remitting MS were enrolled. The experimental group received orally 4 g/day of fish oil for 12 months. The primary outcome was serum TNFα levels; secondary outcomes were IL-1β 1b, IL-6, nitric oxide catabolites, lipoperoxides, progression on the expanded disability status scale (EDSS), and annualized relapses rate (ARR). Fish oil treatment decreased the serum levels of TNFα, IL-1β, IL-6, and nitric oxide metabolites compared with placebo group (P ≤ 0.001). There was no significant difference in serum lipoperoxide levels during the study. No differences in EDSS and ARR were found. Conclusion. Fish oil supplementation is highly effective in reducing the levels of cytokines and nitric oxide catabolites in patients with relapsing-remitting MS. PMID:23861993

  14. Efficacy of fish oil on serum of TNF α , IL-1 β , and IL-6 oxidative stress markers in multiple sclerosis treated with interferon beta-1b.

    PubMed

    Ramirez-Ramirez, V; Macias-Islas, M A; Ortiz, G G; Pacheco-Moises, F; Torres-Sanchez, E D; Sorto-Gomez, T E; Cruz-Ramos, J A; Orozco-Aviña, G; Celis de la Rosa, A J

    2013-01-01

    Multiple sclerosis (MS) is a chronic inflammatory disease, which leads to focal plaques of demyelination and tissue injury in the central nervous system. Oxidative stress is also thought to promote tissue damage in multiple sclerosis. Current research findings suggest that omega-3 polyunsaturated fatty acids (PUFAs) such as eicosapenta-enoic acid (EPA) and docosahexaenoic acid (DHA) contained in fish oil may have anti-inflammatory, antioxidant, and neuroprotective effects. The aim of the present work was to evaluate the efficacy of fish oil supplementation on serum proinflammatory cytokine levels, oxidative stress markers, and disease progression in MS. 50 patients with relapsing-remitting MS were enrolled. The experimental group received orally 4 g/day of fish oil for 12 months. The primary outcome was serum TNF α levels; secondary outcomes were IL-1 β 1b, IL-6, nitric oxide catabolites, lipoperoxides, progression on the expanded disability status scale (EDSS), and annualized relapses rate (ARR). Fish oil treatment decreased the serum levels of TNF α , IL-1 β , IL-6, and nitric oxide metabolites compared with placebo group (P ≤ 0.001). There was no significant difference in serum lipoperoxide levels during the study. No differences in EDSS and ARR were found. Fish oil supplementation is highly effective in reducing the levels of cytokines and nitric oxide catabolites in patients with relapsing-remitting MS.

  15. Multiple sulfur isotope composition of oxidized Samoan melts and the implications of a sulfur isotope 'mantle array' in chemical geodynamics

    NASA Astrophysics Data System (ADS)

    Labidi, J.; Cartigny, P.; Jackson, M. G.

    2015-05-01

    To better address how subducted protoliths drive the Earth's mantle sulfur isotope heterogeneity, we report new data for sulfur (S) and copper (Cu) abundances, S speciation and multiple S isotopic compositions (32S, 33S, 34S, 36S) in 15 fresh submarine basaltic glasses from the Samoan archipelago, which defines the enriched-mantle-2 (EM2) endmember. Bulk S abundances vary between 835 and 2279 ppm. About 17 ± 11% of sulfur is oxidized (S6+) but displays no consistent trend with bulk S abundance or any other geochemical tracer. The S isotope composition of both dissolved sulfide and sulfate yield homogeneous Δ33S and Δ36S values, within error of Canyon Diablo Troilite (CDT). In contrast, δ34S values are variable, ranging between +0.11 and +2.79‰ (±0.12‰ 1σ) for reduced sulfur, whereas oxidized sulfur values vary between +4.19 and +9.71‰ (±0.80‰, 1σ). Importantly, δ34S of the reduced S pool correlates with the 87Sr/86Sr ratios of the glasses, in a manner similar to that previously reported for South-Atlantic MORB, extending the trend to δ34S values up to + 2.79 ± 0.04 ‰, the highest value reported for undegassed oceanic basalts. As for EM-1 basalts from the South Atlantic ridge, the linear δ34S-87Sr/86Sr trend requires the EM-2 endmember to be relatively S-rich, and only sediments can account for these isotopic characteristics. While many authors argue that both the EM-1 and EM-2 mantle components record subduction of various protoliths (e.g. upper or lower continental crust, lithospheric mantle versus intra-metasomatized mantle, or others), it is proposed here that they primarily reflect sediment recycling. Their distinct Pb isotope variation can be accounted for by varying the proportion of S-poor recycled oceanic crust in the source of mantle plumes.

  16. Performance enhancement of multiple-gate ZnO metal-oxide-semiconductor field-effect transistors fabricated using self-aligned and laser interference photolithography techniques

    PubMed Central

    2014-01-01

    The simple self-aligned photolithography technique and laser interference photolithography technique were proposed and utilized to fabricate multiple-gate ZnO metal-oxide-semiconductor field-effect transistors (MOSFETs). Since the multiple-gate structure could improve the electrical field distribution along the ZnO channel, the performance of the ZnO MOSFETs could be enhanced. The performance of the multiple-gate ZnO MOSFETs was better than that of the conventional single-gate ZnO MOSFETs. The higher the drain-source saturation current (12.41 mA/mm), the higher the transconductance (5.35 mS/mm) and the lower the anomalous off-current (5.7 μA/mm) for the multiple-gate ZnO MOSFETs were obtained. PMID:24948884

  17. Neuronal Nitric Oxide Synthase is Involved in Vascular Hyporeactivity and Multiple Organ Dysfunction Associated with Hemorrhagic Shock.

    PubMed

    Sordi, Regina; Chiazza, Fausto; Collino, Massimo; Assreuy, Jamil; Thiemermann, Christoph

    2016-05-01

    Severe hemorrhage can lead to global ischemia and hemorrhagic shock (HS), resulting in multiple organ failure (MOF) and death. Restoration of blood flow and re-oxygenation is associated with an exacerbation of tissue injury and inflammatory response. The neuronal nitric oxide synthase (nNOS) has been implicated in vascular collapse and systemic inflammation of septic shock; however, the role of nNOS in HS is poorly understood. The aim of this study was to evaluate the role of nNOS in the MOF associated with HS.Rats were subjected to HS under anesthesia. Mean arterial pressure was reduced to 30  mmHg for 90  min, followed by resuscitation with shed blood. Rats were randomly treated with two chemically distinct nNOS inhibitors [ARL 17477 (1 mg/kg) and 7-nitroindazol (5 mg/kg)] or vehicle upon resuscitation. Four hours later, parameters of organ injury and dysfunction were assessed.HS was associated with MOF development. Inhibition of nNOS activity at resuscitation protected rats against the MOF and vascular dysfunction. In addition, treatment of HS rats with nNOS inhibitors attenuated neutrophil infiltration into target organs and decreased the activation of NF-κB, iNOS expression, NO production, and nitrosylation of proteins. Furthermore, nNOS inhibition also reduced the levels of pro-inflammatory cytokines TNF-α and IL-6 in HS rats.In conclusion, two distinct inhibitors of nNOS activity reduced the MOF, vascular dysfunction, and the systemic inflammation associated with HS. Thus, nNOS inhibitors may be useful as an adjunct therapy before fluids and blood administration in HS patients to avoid the MOF associated with reperfusion injury during resuscitation.

  18. Nitric oxide-induced murine hematopoietic stem cell fate involves multiple signaling proteins, gene expression, and redox modulation.

    PubMed

    Nogueira-Pedro, Amanda; Dias, Carolina C; Regina, Helena; Segreto, C; Addios, Priscilla C; Lungato, Lisandro; D'Almeida, Vania; Barros, Carlos C; Higa, Elisa M S; Buri, Marcus V; Ferreira, Alice T; Paredes-Gamero, Edgar Julian

    2014-11-01

    There are a growing number of reports showing the influence of redox modulation in cellular signaling. Although the regulation of hematopoiesis by reactive oxygen species (ROS) and reactive nitrogen species (RNS) has been described, their direct participation in the differentiation of hematopoietic stem cells (HSCs) remains unclear. In this work, the direct role of nitric oxide (NO(•)), a RNS, in the modulation of hematopoiesis was investigated using two sources of NO(•) , one produced by endothelial cells stimulated with carbachol in vitro and another using the NO(•)-donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) in vivo. Two main NO(•) effects were observed: proliferation of HSCs-especially of the short-term HSCs-and its commitment and terminal differentiation to the myeloid lineage. NO(•)-induced proliferation was characterized by the increase in the number of cycling HSCs and hematopoietic progenitor cells positive to BrdU and Ki-67, upregulation of Notch-1, Cx43, PECAM-1, CaR, ERK1/2, Akt, p38, PKC, and c-Myc. NO(•)-induced HSCs differentiation was characterized by the increase in granulocytic-macrophage progenitors, granulocyte-macrophage colony forming units, mature myeloid cells, upregulation of PU.1, and C/EBPα genes concomitantly to the downregulation of GATA-3 and Ikz-3 genes, activation of Stat5 and downregulation of the other analyzed proteins mentioned above. Also, redox status modulation differed between proliferation and differentiation responses, which is likely associated with the transition of the proliferative to differentiation status. Our findings provide evidence of the role of NO(•) in inducing HSCs proliferation and myeloid differentiation involving multiple signaling.

  19. Tissue- and development-specific expression of multiple alternatively spliced transcripts of rat neuronal nitric oxide synthase.

    PubMed Central

    Lee, M A; Cai, L; Hübner, N; Lee, Y A; Lindpaintner, K

    1997-01-01

    Nitric oxide (NO) functions as an intercellular messenger and mediates numerous biological functions. Among the three isoforms of NO synthase that produce NO, the ubiquitously expressed neuronal NO synthase (nNOS) is responsible for a large part of NO production, yet its regulation is poorly understood. Recent reports of two alternative spliceforms of nNOS in the mouse and in man have raised the possibility of spatial and temporal modulation of expression. This study demonstrates the existence of at least three transcripts of the rat nNOS gene designated nNOSa, nNOSb, and nNOSc, respectively, with distinct 5' untranslated first exons that arise from alternative splicing to a common second exon. Expression of the alternative transcripts occurs with a high degree of tissue and developmental specificity, as demonstrated by RNase protection assays on multiple tissues from both fetal and adult rats. Furthermore, terminal differentiation of rat pheochromocytoma-derived PC12 cells into neurons is associated with induction of nNOSa, suggesting, likewise, development- and tissue-specific transcriptional control of nNOS isoform expression. Physical mapping using a rat yeast artificial chromosome clone shows that the alternatively spliced first exons 1a, 1b, and 1c are separated by at least 15-60 kb from the downstream coding sequence, with exons 1b and 1c being positioned within 200 bp of each other. These findings provide evidence that the biological activity of nNOS is tightly and specifically regulated by a complex pattern of alternative splicing, indicating that the notion of constitutive expression of this isoform needs to be revised. PMID:9294118

  20. Determination of anesthetic molecule environments by infrared spectroscopy. II. Multiple sites for nitrous oxide in proteins, lipids, and brain tissue.

    PubMed

    Hazzard, J H; Gorga, J C; Caughey, W S

    1985-08-01

    The presence of molecules of the general anesthetic nitrous oxide (N2O) in oils, esters, proteins, red cells, cream, lipid vesicles, and brain tissue upon exposure to the gas was observed by infrared spectroscopy. Analysis of the N-N-O antisymmetric stretch band reveals a distribution of N2O molecules among several sites of differing polarity in these solutions and tissues. The sensitivity of the band intensity and frequency to the number and strength of the dipoles in the solvating molecules is demonstrated by the resolution of N2O-ester and N2O-alkane interactions in acetic acid ethyl ester and oleic acid methyl ester. In all aqueous solutions and in all tissues a population of N2O molecules in water is observed. At least two sites of N2O-protein interaction are observed in purified hemoglobin A and packed red cells; multiple N2O sites may also be present in bovine serum albumin. Two sites of N2O-lipid interaction are observed in whipping cream and in an aqueous suspension of phosphatidylcholine vesicles. The sites providing the least polar immediate environment to N2O in hemoglobin, cream, and vesicles give similar band frequencies to those found in pure alkane solvents. Infrared spectra of bovine brain tissue, upon exposure to N2O, show N2O molecules present in water and in two less-polar environments. Analysis of spectra of N2O in cerebellum tissue removed from a dog under halothane-N2O anesthesia reveals, in addition to N2O in water, a single population of N2O molecules in an alkane-like environment. Infrared spectroscopy provides a unique means of probing the structure of the environment of N2O and should prove useful in correlating anesthetic potency with anesthetic environment under physiological conditions.

  1. One-electron properties and electrostatic interaction energies from the expectation value expression and wave function of singles and doubles coupled cluster theory.

    PubMed

    Korona, Tatiana; Jeziorski, Bogumil

    2006-11-14

    One-electron density matrices resulting from the explicitly connected commutator expansion of the expectation value were implemented at the singles and doubles coupled cluster (CCSD) level. In the proposed approach the one-electron density matrix is obtained at a little extra cost in comparison to the calculation of the CCSD correlation energy. Therefore, in terms of the computational time the new method is significantly less demanding than the conventional linear-response CCSD theory which requires additionally an expensive calculation of the left-hand solution of the CCSD equations. The quality of the new density matrices was investigated by computing a set of one-electron properties for a series of molecules of varying sizes and comparing the results with data obtained using the full configuration interaction method or higher level coupled cluster theory. It has been found that the results obtained using the new approach are of the same quality as those predicted by the linear-response CCSD method. The novel one-electron density matrices have also been applied to study the energy of the electrostatic interaction for a number of van der Waals complexes, including the benzene and azulene dimers.

  2. One-electron oxidation of DNA by ionizing radiation: competition between base-to-base hole-transfer and hole-trapping.

    PubMed

    Sharma, Kiran K K; Tyagi, Rahul; Purkayastha, Shubhadeep; Bernhard, William A

    2010-06-10

    The distance of hole migration through DNA determines the degree to which radiation-induced lesions are clustered. It is the degree of clustering that confers to ionizing radiation its high toxicity. The migration distance is governed by a competition between hole transfer and irreversible trapping reactions. An important type of trapping is reactions that lead to the formation of deoxyribose radicals, which are precursors to free base release (fbr). Using HPLC, fbr was measured in X-irradiated films of d(CGCGCGCGCG)(2) and d(CGCGAATTCGCG)(2) as well as three genomic DNAs: M. luteus, calf thymus, and C. perfringens. The level of DNA hydration was varied from Gamma = 2.5 to 22 mol waters/mol nucleotide. The chemical yields of each base, G(base), were measured and used to calculate the modification factor, M(base). This factor compensates for differences in the GC/AT ratio, providing a measure of the degree to which a given base influences its own release. In the DNA oligomers, M(Gua) > M(Cyt), a result ascribed to the previously observed end effect in short oligomers. In the highly polymerized genomic DNA, we found that M(Cyt) > M(Gua) and that M(Thy) is consistently the smallest of the M factors. For these same DNA films, the yields of total DNA trapped radicals, G(tot)(fr), were measured using EPR spectroscopy. The yield of deoxyribose radicals was calculated using G(dRib)(fr) = approximately 0.11 x G(tot)(fr). Comparing G(dRib)(fr) with total fbr, we found that only about half of the fbr is accounted for by deoxyribose radical intermediates. We conclude that for a hole on cytosine, Cyt(*+), base-to-base hole transfer competes with irreversible trapping by the deoxyribose. In the case of a hole on thymine, Thy(*+), base-to-base hole transfer competes with irreversible trapping by methyl deprotonation. Close proximity of Gua protects the deoxyribose of Cyt but sensitizes the deoxyribose of Thy.

  3. EPR spin-trapping evidence for the direct, one-electron reduction of tert-butylhydroperoxide to the tert-butoxyl radical by copper(II): paradigm for a previously overlooked reaction in the initiation of lipid peroxidation.

    PubMed

    Jones, Clare M; Burkitt, Mark J

    2003-06-11

    Lipid peroxidation is often initiated using Cu(II) ions. It is widely assumed that Cu(II) oxidizes preformed lipid hydroperoxides to peroxyl radicals, which propagate oxidation of the parent fatty acid via hydrogen atom abstraction. However, the oxidation of alkyl hydroperoxides by Cu(II) is thermodynamically unfavorable. An alternative means by which Cu(II) ions could initiate lipid peroxidation is by their one-electron reduction of lipid hydroperoxides to alkoxyl radicals, which would be accompanied by the generation of Cu(III). We have investigated by EPR spectroscopy, in conjunction with the spin trap 5,5-dimethyl-1-pyrroline N-oxide, the reactions of various Cu(II) chelates with tert-butylhydroperoxide. Spectra contained signals from the tert-butoxyl, methyl, and methoxyl radical adducts. In many previous studies, the signal from the methoxyl adduct has been assigned incorrectly to the tert-butylperoxyl adduct, which is now known to be unstable, releasing the tert-butoxyl radical upon decomposition. This either is trapped by 5,5-dimethyl-1-pyrroline N-oxide or undergoes beta-scission to the methyl radical, which either is trapped or reacts with molecular oxygen to give, ultimately, the methoxyl radical adduct. By using metal chelates that are known to be specific in either their oxidation or reduction of tert-butylhydroperoxide (the Cu(II) complex of bathocuproine disulfonic acid and the Fe(II) complex of diethylenetriaminepentaacetic acid, respectively) for comparison, we have been able to deduce, from the relative concentrations of the three radical adducts, that the Cu(II) complexes tested each reduce tert-butylhydroperoxide directly to the tert-butoxyl radical. These findings suggest that a previously overlooked reaction, namely the direct reduction of preformed lipid hydroperoxides to alkoxyl radicals by Cu(II), may be responsible for the initiation of lipid peroxidation by Cu(II) ions.

  4. PM2.5 collected in China causes inflammatory and oxidative stress responses in macrophages through the multiple pathways.

    PubMed

    Bekki, Kanae; Ito, Tomohiro; Yoshida, Yasuhiro; He, Cuiying; Arashidani, Keiichi; He, Miao; Sun, Guifan; Zeng, Yang; Sone, Hideko; Kunugita, Naoki; Ichinose, Takamichi

    2016-07-01

    Air pollution continues to increase in East Asia, particularly in China, and is considered to cause serious health problems. In this study, we investigated the toxicological properties of particulate matter ≤2.5mm (PM2.5) collected in an urban area in China (Shenyang), focusing on inflammation and oxidative stress tightly linked to respiratory diseases. Exposure to PM2.5 significantly increased the expression levels of inflammatory (interleukin-1β and cyclooxygenase-2) and oxidative stress (heme oxygenase1) genes in the mouse macrophages. PM2.5-caused inflammatory response was strongly suppressed by endotoxin neutralizer (polymyxin B) and knock-out of toll-like receptor 4, while oxidative stress was not. On the other hand, an antioxidant (N-acetylcystein) suppressed oxidative stress, but not inflammatory response. These results suggest that PM2.5 in the atmospheric environment of China causes inflammation and oxidative stress in macrophages via separate pathways.

  5. Graphene oxide selectively targets cancer stem cells, across multiple tumor types: implications for non-toxic cancer treatment, via "differentiation-based nano-therapy".

    PubMed

    Fiorillo, Marco; Verre, Andrea F; Iliut, Maria; Peiris-Pagés, Maria; Ozsvari, Bela; Gandara, Ricardo; Cappello, Anna Rita; Sotgia, Federica; Vijayaraghavan, Aravind; Lisanti, Michael P

    2015-02-28

    Tumor-initiating cells (TICs), a.k.a. cancer stem cells (CSCs), are difficult to eradicate with conventional approaches to cancer treatment, such as chemo-therapy and radiation. As a consequence, the survival of residual CSCs is thought to drive the onset of tumor recurrence, distant metastasis, and drug-resistance, which is a significant clinical problem for the effective treatment of cancer. Thus, novel approaches to cancer therapy are needed urgently, to address this clinical need. Towards this end, here we have investigated the therapeutic potential of graphene oxide to target cancer stem cells. Graphene and its derivatives are well-known, relatively inert and potentially non-toxic nano-materials that form stable dispersions in a variety of solvents. Here, we show that graphene oxide (of both big and small flake sizes) can be used to selectively inhibit the proliferative expansion of cancer stem cells, across multiple tumor types. For this purpose, we employed the tumor-sphere assay, which functionally measures the clonal expansion of single cancer stem cells under anchorage-independent conditions. More specifically, we show that graphene oxide effectively inhibits tumor-sphere formation in multiple cell lines, across 6 different cancer types, including breast, ovarian, prostate, lung and pancreatic cancers, as well as glioblastoma (brain). In striking contrast, graphene oxide is non-toxic for "bulk" cancer cells (non-stem) and normal fibroblasts. Mechanistically, we present evidence that GO exerts its striking effects on CSCs by inhibiting several key signal transduction pathways (WNT, Notch and STAT-signaling) and thereby inducing CSC differentiation. Thus, graphene oxide may be an effective non-toxic therapeutic strategy for the eradication of cancer stem cells, via differentiation-based nano-therapy.

  6. The Statistical Evolution of Multiple Generations of Oxidation Products in the Photochemical Aging of Chemically Reduced Organic Aerosol

    SciTech Connect

    Wilson, Kevin R.; Smith, Jared D.; Kessler, Sean; Kroll, Jesse H.

    2011-10-03

    The heterogeneous reaction of hydroxyl radicals (OH) with squalane and bis(2-ethylhexyl) sebacate (BES) particles are used as model systems to examine how distributions of reactionproducts evolve during the oxidation of chemically reduced organic aerosol. A kinetic model of multigenerational chemistry, which is compared to previously measured (squalane) and new(BES) experimental data, reveals that it is the statistical mixtures of different generations of oxidation products that control the average particle mass and elemental composition during thereaction. The model suggests that more highly oxidized reaction products, although initially formed with low probability, play a large role in the production of gas phase reaction products.In general, these results highlight the importance of considering atmospheric oxidation as a statistical process, further suggesting that the underlying distribution of molecules could playimportant roles in aerosol formation as well as in the evolution of key physicochemical properties such as volatility and hygroscopicity.

  7. Multiple pathways for benzyl alcohol oxidation by Ru(V)═O3+ and Ru(IV)═O2+.

    PubMed

    Paul, Amit; Hull, Jonathan F; Norris, Michael R; Chen, Zuofeng; Ess, Daniel H; Concepcion, Javier J; Meyer, Thomas J

    2011-02-21

    Significant rate enhancements are found for benzyl alcohol oxidation by the Ru(V)═O(3+) form of the water oxidation catalyst [Ru(Mebimpy)(bpy)(OH(2))](2+) [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy = 2,2'-bipyridine] compared to Ru(IV)═O(2+) and for the Ru(IV)═O(2+) form with added bases due to a new pathway, concerted hydride proton transfer (HPT).

  8. Demonstration and Architectural Analysis of Complementary Metal-Oxide Semiconductor Multiple-Quantum-Well Smart-Pixel Array Cellular Logic Processors for Single-Instruction Multiple-Data Parallel-Pipeline Processing

    NASA Astrophysics Data System (ADS)

    Wu, Jen-Ming; Kuznia, Charles B.; Hoanca, Bogdan; Chen, Chih-Hao; Sawchuk, Alexander A.

    1999-04-01

    We present an optoelectronic-VLSI system that integrates complementary metal-oxide semiconductor multiple-quantum-well smart pixels for high-throughput computation and signal processing. The system uses 5 10 cellular smart-pixel arrays with intrachip electrical mesh interconnections and interchip optical point-to-point interconnections. Each smart pixel is a fine grain microprocessor that executes binary image algebra instructions. There is one dual-rail optical modulator output and one dual-rail optical detector input in each pixel. These optical input output arrays provide chip-to-chip optical interconnects. Cascading these smart-pixel array chips permits direct transfer of two-dimensional data or images in parallel. We present laboratory demonstrations of the system for digital image edge detection and digital video motion estimation. We also analyze the performance of the system compared with that of conventional single-instruction multiple-data processors.

  9. Demonstration and architectural analysis of complementary metal-oxide semiconductor /multiple-quantum-well smart-pixel array cellular logic processors for single-instruction multiple-data parallel-pipeline processing.

    PubMed

    Wu, J M; Kuznia, C B; Hoanca, B; Chen, C H; Sawchuk, A A

    1999-04-10

    We present an optoelectronic-VLSI system that integrates complementary metal-oxide semiconductor/multiple-quantum-well smart pixels for high-throughput computation and signal processing. The system uses 5 x 10 cellular smart-pixel arrays with intrachip electrical mesh interconnections and interchip optical point-to-point interconnections. Each smart pixel is a fine grain microprocessor that executes binary image algebra instructions. There is one dual-rail optical modulator output and one dual-rail optical detector input in each pixel. These optical input-output arrays provide chip-to-chip optical interconnects. Cascading these smart-pixel array chips permits direct transfer of two-dimensional data or images in parallel. We present laboratory demonstrations of the system for digital image edge detection and digital video motion estimation. We also analyze the performance of the system compared with that of conventional single-instruction-multiple-data processors.

  10. Analysis of multiple haloarchaeal genomes suggests that the quinone-dependent respiratory nitric oxide reductase is an important source of nitrous oxide in hypersaline environments.

    PubMed

    Torregrosa-Crespo, Javier; González-Torres, Pedro; Bautista, Vanesa; Esclapez, Julia M; Pire, Carmen; Camacho, Mónica; Bonete, María José; Richardson, David J; Watmough, Nicholas J; Martínez-Espinosa, Rosa María

    2017-09-19

    Microorganisms, including Bacteria and Archaea, play a key role in denitrification, which is the major mechanism by which fixed nitrogen returns to the atmosphere from soil and water. Whilst the enzymology of denitrification is well understood in Bacteria, the details of the last two reactions in this pathway, which catalyse the reduction of nitric oxide (NO) via nitrous oxide (N2 O) to nitrogen (N2 ), are little studied in Archaea, and hardly at all in haloarchaea. This work describes an extensive interspecies analysis of both complete and draft haloarchaeal genomes aimed at identifying the genes that encode respiratory nitric oxide reductases (Nors). The study revealed that the only nor gene found in haloarchaea is one that encodes a single subunit quinone dependent Nor homologous to the qNor found in bacteria. This surprising discovery is considered in terms of our emerging understanding of haloarchaeal bioenergetics and NO management. This article is protected by copyright. All rights reserved. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Decreased fatty acid beta-oxidation in riboflavin-responsive, multiple acylcoenzyme A dehydrogenase-deficient patients is associated with an increase in uncoupling protein-3.

    PubMed

    Russell, Aaron P; Schrauwen, Patrick; Somm, Emmanuel; Gastaldi, Giacomo; Hesselink, Matthijs K C; Schaart, Gert; Kornips, Esther; Lo, Sing Kai; Bufano, Daniela; Giacobino, Jean-Paul; Muzzin, Patrick; Ceccon, Mara; Angelini, Corrado; Vergani, Lodovica

    2003-12-01

    Riboflavin-responsive, multiple acylcoenzyme A dehydrogenase deficiency (RR-MAD), a lipid storage myopathy, is characterized by, among others, a decrease in fatty acid (FA) beta-oxidation capacity. Muscle uncoupling protein 3 (UCP3) is up-regulated under conditions that either increase the levels of circulating free FA and/or decrease FA beta-oxidation. Using a relatively large cohort of seven RR-MAD patients, we aimed to better characterize the metabolic disturbances of this disease and to explore the possibility that it might increase UCP3 expression. A battery of biochemical and molecular tests were performed, which demonstrated decreases in FA beta-oxidation and in the activities of respiratory chain complexes I and II. These metabolic alterations were associated with increases of 3.1- and 1.7-fold in UCP3 mRNA and protein expression, respectively. All parameters were restored to control values after riboflavin treatment. We postulate that the up-regulation of UCP3 in RR-MAD is due to the accumulation of muscle FA/acylCoA. RR-MAD is an optimal model to support the hypothesis that UCP3 is involved in the outward translocation of an excess of FA from the mitochondria and to show that, in humans, the effects of FA on UCP3 expression are direct and independent of fatty acid beta-oxidation.

  12. Silibinin attenuates sulfur mustard analog-induced skin injury by targeting multiple pathways connecting oxidative stress and inflammation.

    PubMed

    Tewari-Singh, Neera; Jain, Anil K; Inturi, Swetha; Agarwal, Chapla; White, Carl W; Agarwal, Rajesh

    2012-01-01

    Chemical warfare agent sulfur mustard (HD) inflicts delayed blistering and incapacitating skin injuries. To identify effective countermeasures against HD-induced skin injuries, efficacy studies were carried out employing HD analog 2-chloroethyl ethyl sulfide (CEES)-induced injury biomarkers in skin cells and SKH-1 hairless mouse skin. The data demonstrate strong therapeutic efficacy of silibinin, a natural flavanone, in attenuating CEES-induced skin injury and oxidative stress. In skin cells, silibinin (10 µM) treatment 30 min after 0.35/0.5 mM CEES exposure caused a significant (p<0.05) reversal in CEES-induced decrease in cell viability, apoptotic and necrotic cell death, DNA damage, and an increase in oxidative stress. Silibinin (1 mg) applied topically to mouse skin 30 min post-CEES exposure (2 mg), was effective in reversing CEES-induced increases in skin bi-fold (62%) and epidermal thickness (85%), apoptotic cell death (70%), myeloperoxidase activity (complete reversal), induction of iNOS, COX-2, and MMP-9 protein levels (>90%), and activation of transcription factors NF-κB and AP-1 (complete reversal). Similarly, silibinin treatment was also effective in attenuating CEES-induced oxidative stress measured by 4-hydroxynonenal and 5,5-dimethyl-2-(8-octanoic acid)-1-pyrolline N-oxide protein adduct formation, and 8-oxo-2-deoxyguanosine levels. Since our previous studies implicated oxidative stress, in part, in CEES-induced toxic responses, the reversal of CEES-induced oxidative stress and other toxic effects by silibinin in this study indicate its pleiotropic therapeutic efficacy. Together, these findings support further optimization of silibinin in HD skin toxicity model to develop a novel effective therapy for skin injuries by vesicants.

  13. Coulomb Blockade of the Conductivity of SiO{sub x} Films Due to One-Electron Charging of a Silicon Quantum Dot in a Chain of Electronic States

    SciTech Connect

    Efremov, M.D.; Kamaev, G.N.; Volodin, V.A.; Arzhannikova, S.A.; Kachurin, G.A.; Cherkova, S.G.; Kretinin, A.V.; Malyutina-Bronskaya, V.V.; Marin, D.V.

    2005-08-15

    The electrical characteristics of metal-oxide-semiconductor (MOS) structures with silicon nanoparticles embedded in silicon oxide have been studied. The nanocrystals are formed by decomposition of an oversaturated solid solution of implanted silicon during thermal annealing at a temperature of {approx}1000 deg. C. At liquid-nitrogen temperature, a stepped current-voltage characteristic is observed in a MOS structure consisting of Si nanocrystals in a SiO{sub 2} film. The stepped current-voltage characteristic is, for the first time, quantitatively described using a model in which charge transport occurs via a chain of local states containing a silicon nanocrystal. The presence of steps is found to be associated with one-electron charging of the silicon nanocrystal and Coulomb blockade of the probability of a hop from the nearest local state to the conducting chain. The local states in silicon dioxide are assumed to be related to an excess of silicon atoms. The presence of such states is confirmed by measurements of the differential conductance and capacitance. For MOS structures implanted with silicon, the differential capacitance and conductance are found to be higher, compared to the reference structures, in the range of biases exceeding 0.2 V. In the same bias range, the conductance is observed to decrease under ultraviolet irradiation due to a change in the population of the states in the conductivity chains.

  14. Mitochondrial-Targeted Decyl-Triphenylphosphonium Enhances 2-Deoxy-D-Glucose Mediated Oxidative Stress and Clonogenic Killing of Multiple Myeloma Cells

    PubMed Central

    Schibler, Jeanine; Tomanek-Chalkley, Ann M.; Reedy, Jessica L.; Zhan, Fenghuang; Spitz, Douglas R.; Schultz, Michael K.; Goel, Apollina

    2016-01-01

    Therapeutic advances have markedly prolonged overall survival in multiple myeloma (MM) but the disease currently remains incurable. In a panel of MM cell lines (MM.1S, OPM-2, H929, and U266), using CD138 immunophenotyping, side population staining, and stem cell-related gene expression, we demonstrate the presence of stem-like tumor cells. Hypoxic culture conditions further increased CD138low stem-like cells with upregulated expression of OCT4 and NANOG. Compared to MM cells, these stem-like cells maintained lower steady-state pro-oxidant levels with increased uptake of the fluorescent deoxyglucose analog. In primary human MM samples, increased glycolytic gene expression correlated with poorer overall and event-free survival outcomes. Notably, stem-like cells showed increased mitochondrial mass, rhodamine 123 accumulation, and orthodox mitochondrial configuration while more condensed mitochondria were noted in the CD138high cells. Glycolytic inhibitor 2-deoxyglucose (2-DG) induced ER stress as detected by qPCR (BiP, ATF4) and immunoblotting (BiP, CHOP) and increased dihydroethidium probe oxidation both CD138low and CD138high cells. Treatment with a mitochondrial-targeting agent decyl-triphenylphosphonium (10-TPP) increased intracellular steady-state pro-oxidant levels in stem-like and mature MM cells. Furthermore, 10-TPP mediated increases in mitochondrial oxidant production were suppressed by ectopic expression of manganese superoxide dismutase. Relative to 2-DG or 10-TPP alone, 2-DG plus 10-TPP combination showed increased caspase 3 activation in MM cells with minimal toxicity to the normal hematopoietic progenitor cells. Notably, treatment with polyethylene glycol conjugated catalase significantly reduced 2-DG and/or 10-TPP-induced apoptosis of MM cells. Also, the combination of 2-DG with 10-TPP decreased clonogenic survival of MM cells. Taken together, this study provides a novel strategy of metabolic oxidative stress-induced cytotoxicity of MM cells via 2-DG

  15. One electron in a cavity

    SciTech Connect

    Gabrielse, G.; Tan, J.

    1994-12-31

    Measurements of the anomalous magnetic moment of the electron a provide the most stringent test of quantum electrodynamics (QED). This theory predicts corrections to the simplest Dirac theory due to the interaction of an electron with the fluctuating radiation modes of the electromagnetic vacuum. It relates a to an asymptotic series in powers of the fine structure constant {alpha}. 40 refs., 23 figs.

  16. Initial step of B12-dependent enzymatic catalysis: energetic implications regarding involvement of the one-electron-reduced form of adenosylcobalamin cofactor.

    PubMed

    Kozlowski, Pawel M; Kamachi, Takashi; Kumar, Manoj; Yoshizawa, Kazunari

    2012-02-01

    Density functional theory analysis was performed to elucidate the impact of one-electron reduction upon the initial step of adenosylcobalamin-dependent enzymatic catalysis. The transition state (TS) corresponding to the Co-C bond cleavage and subsequent hydrogen abstraction from the substrate was located. The intrinsic reaction coordinate calculations predicted that the reaction consisting of Co-C5' bond cleavage in [Co(III)(corrin(•))]-Rib (where Rib is ribosyl) and hydrogen-atom abstraction from the CH(3)-CH(2)-CHO substrate occurs in a concerted fashion. The computed activation energy barrier of the reaction (15.0 kcal/mol) was lowered by approximately 54.5% in comparison with the reaction involving the positively charged cofactor model (Im-[Co(III)(corrin)]-Rib(+), where Im is imidazole; energy barrier = 33.0 kcal/mol). The Im base was detached during the TS search in the reaction involving the one-electron-reduced analogue. Thus, to compare the energetics of the two reactions, the axial Im ligand detachment energy for the Im-[Co(III)(corrin(•))]-Rib model was computed [7.6 kcal/mol (gas phase); 4.6 kcal/mol (water)]. Consequently, the effective activation energy barrier for the reaction mediated by the Im-off [Co(III)(corrin(•))]-Rib was estimated to be 22.6 kcal/mol, which implied an overall 31.5% reduction in the energetic demands of the reaction. Considering that the lengthened Co-N(axial) bond has been observed in X-ray crystal structure studies of B(12)-dependent mutases, the catalytic impact induced by one-electron reduction of the cofactor is expected to be higher in the presence of the enzymatic environment.

  17. Assay of impure plutonium oxide with the large neutron multiplicity counter for IAEA verification of excess weapons material at the Rocky Flats Environmental Technology Site

    SciTech Connect

    Langner, D.G.; Franco, J.B.; Larsen, R.K.

    1997-11-01

    The large neutron multiplicity counter (LNMC), also known as the 30-gal.-drum neutron multiplicity counter, has now been used successfully by the International Atomic Energy Agency (IAEA) for the Initial Physical Inventory Verification (IPIV) and the first annual Physical Inventory Verification (PIV) of excess weapons plutonium oxide at the Rocky Flats Environmental Technology Site (RFETS). These excess plutonium oxide materials contain a variety of impurities. They are stored two cans to a 10-gal.-drum. The drums contain from 1.3 to 4.0 kg of plutonium. The isotopic declarations vary from can to can but the material averages 6% {sup 240}Pu. During the IPIV, 94 samples were measured in the LNMC; 19 were measured during the PIV. The assays for all but a single drum agreed to within three standard deviations of the declared value. This problematic drum could not be measured by the LNMC because of its unusually high neutron emission rate. In this paper we will report on the overall performance of the LNMC in these inspections.

  18. An Overview of Methods in Plant Nitric Oxide (NO) Research: Why Do We Always Need to Use Multiple Methods?

    PubMed

    Yamasaki, Hideo; Watanabe, Naoko S; Sakihama, Yasuko; Cohen, Michael F

    2016-01-01

    The free radical nitric oxide (NO) is a universal signaling molecule among living organisms. To investigate versatile functions of NO in plants it is essential to analyze biologically produced NO with an appropriate method. Owing to the uniqueness of NO, plant researchers may encounter difficulties in applying methods that have been developed for mammalian study. Based on our experience, we present here a practical guide to NO measurement fitted to plant biology.

  19. Vegetables’ juice influences polyol pathway by multiple mechanisms in favour of reducing development of oxidative stress and resultant diabetic complications

    PubMed Central

    Tiwari, Ashok K.; Kumar, D. Anand; Sweeya, Pisupati S.; Chauhan, H. Anusha; Lavanya, V.; Sireesha, K.; Pavithra, K.; Zehra, Amtul

    2014-01-01

    Objective: Hyperglycemia induced generation of free radicals and consequent development of oxidative stress by polyol pathway is one of the crucial mechanisms stirring up development of diabetic complications. We evaluated influence of ten vegetables’ juice on polyol pathway along with their antioxidant and antioxidative stress potentials. Materials and Methods: Aldose reductase activity was determined utilising goat lens and human erythrocytes. In goat lens, utilization of nicotinamine adenine dinucleotide phosphate (NADPH) and aldose reductase inhibition was assayed. In human erythrocytes, sorbitol formation was measured as an index of aldose reductase activity under normoglycemic and hyperglycemic conditions. Ability of juices in inhibiting oxidative damage to deoxyribose sugar and calf thymus DNA and inhibitory activity against hydrogen peroxide induced hemolysis of erythrocytes was also analysed. Phytochemical contents like total polyphenol, total flavonoid and total protein were measured to find their influence on biological activities. Results: Vegetables’ juice displayed varying degrees of inhibitory potentials in mitigating NADPH dependent catalytic activity of aldose reductase in goat lens, accumulation of sorbitol in human erythrocytes under different glucose concentrations; Fenton-reaction induced oxidative damage to deoxyribose sugar, and calf thymus DNA. Substantial variations in vegetables phytochemicals content were also noticed in this study. Conclusions: Vegetables’ juice possesses potent activities in influencing polyol pathway by various mechanisms in favour of reducing development of oxidative stress independent of their inherent antioxidative properties. Juice of ivy gourd followed by green cucumber and ridge gourd were among the most potent for they displayed strong activities on various parameters analysed in this study. These vegetables’ juice may become part of mechanism-based complementary antioxidant therapy to prevent

  20. Neighboring amide participation in thioether oxidation: relevance to biological oxidation.

    PubMed

    Glass, Richard S; Hug, Gordon L; Schöneich, Christian; Wilson, George S; Kuznetsova, Larisa; Lee, Tang-man; Ammam, Malika; Lorance, Edward; Nauser, Thomas; Nichol, Gary S; Yamamoto, Takuhei

    2009-09-30

    To investigate neighboring amide participation in thioether oxidation, which may be relevant to brain oxidative stress accompanying beta-amyloid peptide aggregation, conformationally constrained methylthionorbornyl derivatives with amido moieties were synthesized and characterized, including an X-ray crystallographic study of one of them. Electrochemical oxidation of these compounds, studied by cyclic voltammetry, revealed that their oxidation peak potentials were less positive for those compounds in which neighboring group participation was geometrically possible. Pulse radiolysis studies provided evidence for bond formation between the amide moiety and sulfur on one-electron oxidation in cases where the moieties are juxtaposed. Furthermore, molecular constraints in spiro analogues revealed that S-O bonds are formed on one-electron oxidation. DFT calculations suggest that isomeric sigma*(SO) radicals are formed in these systems.

  1. Markers of oxidative/nitrative damage of plasma proteins correlated with EDSS and BDI scores in patients with secondary progressive multiple sclerosis.

    PubMed

    Morel, Agnieszka; Bijak, Michał; Niwald, Marta; Miller, Elżbieta; Saluk, Joanna

    2017-05-19

    Objectives The objective of the present study was to evaluate oxidative/nitrative stress in the plasma of 50 patients suffering from the secondary progressive course of multiple sclerosis (MS), and to verify its correlation with physical and mental disability as assessed by the Expanded Disability Status Scale (EDSS), and the Beck Depression Inventory (BDI). Methods Oxidative and nitrative damage to proteins was determined by the level of carbonyl groups and 3-nitrotyrosine using ELISA test. Based on the reaction with Ellman's reagent, we estimated the concentration of oxidized thiol groups. Additionally, we measured the level of lipid peroxidation. Results In plasma drawn from MS patients, we observed a significantly higher level of 3-NT (92%; P < 0.0003), carbonyl groups (29%; P < 0.0001) and thiobarbituric acid reactive substances (73%; P < 0.0001), as well as a lower concentration of thiol groups (33%; P < 0.0001), in comparison to healthy subjects. We noted positive correlations between the level of carbonyl groups or 3-NT and both diagnostic parameters, EDSS and BDI. Negative correlations were observed between concentration of -SH groups and EDSS and BDI. Conclusion Our results indicate that impaired red-ox balance can significantly promote neurodegeneration in secondary progressive MS.

  2. Analytic energy gradients for the spin-free exact two-component theory using an exact block diagonalization for the one-electron Dirac Hamiltonian.

    PubMed

    Cheng, Lan; Gauss, Jürgen

    2011-08-28

    We report the implementation of analytic energy gradients for the evaluation of first-order electrical properties and nuclear forces within the framework of the spin-free (SF) exact two-component (X2c) theory. In the scheme presented here, referred to in the following as SFX2c-1e, the decoupling of electronic and positronic solutions is performed for the one-electron Dirac Hamiltonian in its matrix representation using a single unitary transformation. The resulting two-component one-electron matrix Hamiltonian is combined with untransformed two-electron interactions for subsequent self-consistent-field and electron-correlated calculations. The "picture-change" effect in the calculation of properties is taken into account by considering the full derivative of the two-component Hamiltonian matrix with respect to the external perturbation. The applicability of the analytic-gradient scheme presented here is demonstrated in benchmark calculations. SFX2c-1e results for the dipole moments and electric-field gradients of the hydrogen halides are compared with those obtained from nonrelativistic, SF high-order Douglas-Kroll-Hess, and SF Dirac-Coulomb calculations. It is shown that the use of untransformed two-electron interactions introduces rather small errors for these properties. As a first application of the analytic geometrical gradient, we report the equilibrium geometry of methylcopper (CuCH(3)) determined at various levels of theory.

  3. Au-ionic liquid functionalized reduced graphene oxide immunosensing platform for simultaneous electrochemical detection of multiple analytes.

    PubMed

    Liu, Na; Ma, Zhanfang

    2014-01-15

    In this work, an Au-ionic liquid functionalized reduced graphene oxide nanocomposite (IL-rGO-Au) was fabricated via the self-assembly of ionic liquid functionalized reduced graphene oxide (IL-rGO) and gold nanoparticles (AuNPs) by electrostatic interaction. The IL-rGO can be synthesized and stabilized by introducing the cations of the amine-terminated ionic liquids (IL-NH2) into the graphene oxide (GO). With the assistance of IL-NH2, AuNPs were uniformly and densely absorbed on the surfaces of the IL-rGO. The proposed IL-rGO-Au nanocomposite can be used as an immunosensing platform because it can not only facilitate the electrons transfer of the electrode surface but also provide a large accessible surface area for the immobilization of abundant antibody. To assess the performance of the IL-rGO-Au nanocomposite, a sandwich-type electrochemical immunosensor was designed for simultaneous multianalyte detection (carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) as model analytes). The chitosan (CS) coated prussian blue nanoparticles (PBNPs) or cadmium hexacyanoferrate nanoparticles (CdNPs) and loaded with AuNPs were used as distinguishable signal tags. The resulting immunosensor exhibited high selectivity and sensitivity in simultaneous determination of CEA and AFP in a single run. The linear ranges were from 0.01 to 100 ng mL(-1) for both CEA and AFP. The detection limits reached 0.01 ng mL(-1) for CEA and 0.006 ng mL(-1) for AFP, respectively. No obvious nonspecific adsorption and cross-talk was observed during a series of analyses to detect target analytes. In addition, for the detection of clinical serum samples, it is well consistent with the data determined by the ELISA, indicating that the immunosensor provides a possible application for the simultaneous multianalyte determination of CEA and AFP in clinical diagnostics.

  4. Biodistribution of a High Dose of Diamond, Graphite, and Graphene Oxide Nanoparticles After Multiple Intraperitoneal Injections in Rats.

    PubMed

    Kurantowicz, Natalia; Strojny, Barbara; Sawosz, Ewa; Jaworski, Sławomir; Kutwin, Marta; Grodzik, Marta; Wierzbicki, Mateusz; Lipińska, Ludwika; Mitura, Katarzyna; Chwalibog, André

    2015-12-01

    Carbon nanoparticles have recently drawn intense attention in biomedical applications. Hence, there is a need for further in vivo investigations of their biocompatibility and biodistribution via various exposure routes. We hypothesized that intraperitoneally injected diamond, graphite, and graphene oxide nanoparticles may have different biodistribution and exert different effects on the intact organism. Forty Wistar rats were divided into four groups: the control and treated with nanoparticles by intraperitoneal injection (4 mg of nanoparticles/kg body weight) eight times during the 4-week period. Blood was collected for evaluation of blood morphology and biochemistry parameters. Photographs of the general appearance of each rat's interior were taken immediately after sacrifice. The organs were excised and their macroscopic structure was visualized using a stereomicroscope. The nanoparticles were retained in the body, mostly as agglomerates. The largest agglomerates (up to 10 mm in diameter) were seen in the proximity of the injection place in the stomach serous membrane, between the connective tissues of the abdominal skin, muscles, and peritoneum. Numerous smaller, spherical-shaped aggregates (diameter around 2 mm) were lodged among the mesentery. Moreover, in the connective and lipid tissue in the proximity of the liver and spleen serosa, small aggregates of graphite and graphene oxide nanoparticles were observed. However, all tested nanoparticles did not affect health and growth of rats. The nanoparticles had no toxic effects on blood parameters and growth of rats, suggesting their potential applicability as remedies or in drug delivery systems.

  5. Biodistribution of a High Dose of Diamond, Graphite, and Graphene Oxide Nanoparticles After Multiple Intraperitoneal Injections in Rats

    NASA Astrophysics Data System (ADS)

    Kurantowicz, Natalia; Strojny, Barbara; Sawosz, Ewa; Jaworski, Sławomir; Kutwin, Marta; Grodzik, Marta; Wierzbicki, Mateusz; Lipińska, Ludwika; Mitura, Katarzyna; Chwalibog, André

    2015-10-01

    Carbon nanoparticles have recently drawn intense attention in biomedical applications. Hence, there is a need for further in vivo investigations of their biocompatibility and biodistribution via various exposure routes. We hypothesized that intraperitoneally injected diamond, graphite, and graphene oxide nanoparticles may have different biodistribution and exert different effects on the intact organism. Forty Wistar rats were divided into four groups: the control and treated with nanoparticles by intraperitoneal injection (4 mg of nanoparticles/kg body weight) eight times during the 4-week period. Blood was collected for evaluation of blood morphology and biochemistry parameters. Photographs of the general appearance of each rat's interior were taken immediately after sacrifice. The organs were excised and their macroscopic structure was visualized using a stereomicroscope. The nanoparticles were retained in the body, mostly as agglomerates. The largest agglomerates (up to 10 mm in diameter) were seen in the proximity of the injection place in the stomach serous membrane, between the connective tissues of the abdominal skin, muscles, and peritoneum. Numerous smaller, spherical-shaped aggregates (diameter around 2 mm) were lodged among the mesentery. Moreover, in the connective and lipid tissue in the proximity of the liver and spleen serosa, small aggregates of graphite and graphene oxide nanoparticles were observed. However, all tested nanoparticles did not affect health and growth of rats. The nanoparticles had no toxic effects on blood parameters and growth of rats, suggesting their potential applicability as remedies or in drug delivery systems.

  6. Pigment epithelium-derived factor (PEDF) inhibits survival and proliferation of VEGF-exposed multiple myeloma cells through its anti-oxidative properties.

    PubMed

    Seki, Ritsuko; Yamagishi, Sho-ichi; Matsui, Takanori; Yoshida, Takafumi; Torimura, Takuji; Ueno, Takato; Sata, Michio; Okamura, Takashi

    2013-02-22

    Vascular endothelial growth factor (VEGF) has been reported not only to induce angiogenesis within the bone marrow, but also directly stimulate the proliferation and survival of multiple myeloma cells, thus being involved in the development and progression of this second most common hematological malignancy. We, along with others, have found that pigment epithelium-derived factor (PEDF) has anti-angiogenic and anti-vasopermeability properties both in cell culture and animal models by counteracting the biological actions of VEGF. However, effects of PEDF on VEGF-exposed myeloma cells remain unknown. In this study, we examined whether and how PEDF could inhibit the VEGF-induced proliferation and survival of myeloma cells. PEDF, a glutathione peroxidase mimetic, ebselen, or an inhibitor of NADPH oxidase, diphenylene iodonium significantly inhibited the VEGF-induced reactive oxygen species (ROS) generation, increase in anti-apoptotic and growth-promoting factor, myeloid cell leukemia 1 (Mcl-1) expression, and proliferation in U266 myeloma cells. VEGF blocked apoptosis of multiple myeloma cells isolated from patients, which was prevented by PEDF. PEDF also reduced p22phox levels in VEGF-exposed U266 cells. Furthermore, overexpression of dominant-negative human Rac-1 mutant mimicked the effects of PEDF on ROS generation and Mcl-1 expression in U266 cells. Our present study suggests that PEDF could block the VEGF-induced proliferation and survival of multiple myeloma U266 cells through its anti-oxidative properties via suppression of p22phox, one of the membrane components of NADPH oxidase. Suppression of VEGF signaling by PEDF may be a novel therapeutic target for multiple myeloma.

  7. A traditional Korean multiple herbal formulae (Yuk-Mi-Jihwang-Tang) attenuates acute restraint stress-induced brain tissue oxidation.

    PubMed

    Choi, Hyoung-Il; Lee, Hye-Won; Eom, Tae-Min; Lim, Sung-Ah; Ha, Hun-Yong; Seol, In-Chan; Kim, Yoon-Sik; Oh, Dal-Seok; Yoo, Ho-Ryong

    2017-04-01

    We aimed to evaluate the protective effects of Yuk-Mi-Jihwang-Tang (YJT) against acute restraint stress-induced brain oxidative damage. A water extract of YJT was prepared and subjected to high performance liquid chromatography - diode array detector-mass spectrometry (HPLC-DAD-MS). Thirty-six heads of C57BL/6J male mice (7 weeks) were divided into six groups (n = 6/group). The mice were orally administrated YJT (0, 50, 100, or 200 mg/kg) or vitamin C (100 mg/kg) for 5 consecutive days before 6 h of acute restraint stress. In the brain tissue, lipidperoxidation, antioxidant components, and pro-inflammatory cytokines were measured, and the serum corticosterone level was determined. Acute restraint stress-induced notably increased lipid peroxidation in brain tissues, and pretreatment with YJT showed a significant decreased the lipid peroxidation levels (p< 0.05). The levels of antioxidant components including total glutathione contents, activities of SOD and catalase were remarkably depleted by acute restraint stress, whereas these alterations were significantly restored by treatment with YJT (p< 0.05 or p< 0.01). The restraint stress markedly increased pro-inflammatory cytokines, such as TNF-α and IL-6 in the gene expression and protein levels (p< 0.05 or p< 0.01). Pretreatment with YJT significantly attenuated serum corticosterone (200 mg/kg, p < 0.05). YJT drastically attenuated the levels of 4- HNE, HO-1, Nox 2 and iNOSwhich were elevated during acute restraint stress, whereas the Nrf2 level was increased in brain tissue protein levels. Our data suggest that YJT protects the brain tissue against oxidative damage and regulates stress hormones.

  8. Analysis, Design, and Optimization of Matched-Impedance Wide-Band Amplifiers With Multiple Feedback Loops Using 0.18 μm Complementary Metal Oxide Semiconductor Technology

    NASA Astrophysics Data System (ADS)

    Lin, Yo-Sheng; Lee, Tai-Hsing

    2004-10-01

    The realization of matched-impedance wide-band amplifier fabricated by 0.18 μm complementary metal oxide semiconductor (CMOS) process is reported. The technique of multiple feedback loops was used in the amplifier for terminal impedance matching and wide bandwidth simultaneously. The experimental results show that 3-dB bandwidth of 3 GHz and a gain of 10.7 dB with in-band input/output return loss more than 10 dB are obtained. These values agree well with those predicted from the analytic expressions derived for voltage gain, trans-impedance gain, bandwidth, and input/output return loss and impedance. In addition, the use of source capacitive peaking technique can improve the intrinsic over-damped characteristic of this amplifier.

  9. Synthesis of TiO2 nanoparticles containing Fe, Si, and V using multiple diffusion flames and catalytic oxidation capability of carbon-coated nanoparticles

    NASA Astrophysics Data System (ADS)

    Ismail, Mohamed A.; Memon, Nasir K.; Hedhili, Mohamed N.; Anjum, Dalaver H.; Chung, Suk Ho

    2016-01-01

    Titanium dioxide (TiO2) nanoparticles containing iron, silicon, and vanadium are synthesized using multiple diffusion flames. The growth of carbon-coated (C-TiO2), carbon-coated with iron oxide (Fe/C-TiO2), silica-coated (Si-TiO2), and vanadium-doped (V-TiO2) TiO2 nanoparticles is demonstrated using a single-step process. Hydrogen, oxygen, and argon are utilized to establish the flame, with titanium tetraisopropoxide (TTIP) as the precursor for TiO2. For the growth of Fe/C-TiO2 nanoparticles, TTIP is mixed with xylene and ferrocene. While for the growth of Si-TiO2 and V-TiO2, TTIP is mixed with hexamethyldisiloxane (HMDSO) and vanadium (V) oxytriisopropoxide, respectively. The synthesized nanoparticles are characterized using high-resolution transmission electron microscopy (HRTEM) with energy-filtered TEM for elemental mapping (of Si, C, O, and Ti), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption BET surface area analysis, and thermogravimetric analysis. Anatase is the dominant phase for the C-TiO2, Fe/C-TiO2, and Si-TiO2 nanoparticles, whereas rutile is the dominant phase for the V-TiO2 nanoparticles. For C-TiO2 and Fe/C-TiO2, the nanoparticles are coated with about 3-5-nm thickness of carbon. The iron-based TiO2 nanoparticles significantly improve the catalytic oxidation of carbon, where complete oxidation of carbon occurs at a temperature of 470 °C (with iron) compared to 610 °C (without iron). Enhanced catalytic oxidation properties are also observed for model soot particles, Printex-U, when mixed with Fe/C-TiO2. With regards to Si-TiO2 nanoparticles, a uniform coating of 3 to 8 nm of silicon dioxide is observed around the TiO2 particles. This coating mainly occurs due to variance in the chemical reaction rates of the precursors. Finally, with regards to V-TiO2, vanadium is doped within the TiO2 nanoparticles as visualized by HRTEM and XPS further confirms the formation of V4+ and V5+ oxidation states.

  10. Communication: satisfying fermionic statistics in the modeling of open time-dependent quantum systems with one-electron reduced density matrices.

    PubMed

    Head-Marsden, Kade; Mazziotti, David A

    2015-02-07

    For an open, time-dependent quantum system, Lindblad derived the most general modification of the quantum Liouville equation in the Markovian approximation that models environmental effects while preserving the non-negativity of the system's density matrix. While Lindblad's modification is correct for N-electron density matrices, solution of the Liouville equation with a Lindblad operator causes the one-electron reduced density matrix (1-RDM) to violate the Pauli exclusion principle. Consequently, after a short time, the 1-RDM is not representable by an ensemble N-electron density matrix (not ensemble N-representable). In this communication, we derive the necessary and sufficient constraints on the Lindbladian matrix within the Lindblad operator to ensure that the 1-RDM remains N-representable for all time. The theory is illustrated by considering the relaxation of an excitation in several molecules F2, N2, CO, and BeH2 subject to environmental noise.

  11. Orthogonal natural atomic orbitals form an appropriate one-electron basis for expanding CASSCF wave functions into localized bonding schemes and their weights.

    PubMed

    Bachler, Vinzenz

    2007-09-01

    Localized bonding schemes and their weights have been obtained for the pi-electron system of nitrone by expanding complete active space self-consistent field wave functions into a set of Slater determinants composed of orthogonal natural atomic orbitals (NAOs) of Weinhold and Landis (Valency and Bonding: A Natural Bond Orbital Donor-Acceptor Perspective, 2005). Thus, the derived bonding schemes are close to orthogonal valence bond structures. The calculated sequence of bonding scheme weights accords with the sequence of genuine resonance structure weights derived previously by Ohanessian and Hiberty (Chem Phys Lett 1987, 137, 437), who employed nonorthogonal atomic orbitals. This accord supports the notion that NAOs form an appropriate orthogonal one-electron basis for expanding complete active space self-consistent field wave functions into meaningful bonding schemes and their weights.

  12. Multiple-stimuli responsive bioelectrocatalysis based on reduced graphene oxide/poly(N-isopropylacrylamide) composite films and its application in the fabrication of logic gates.

    PubMed

    Wang, Lei; Lian, Wenjing; Yao, Huiqin; Liu, Hongyun

    2015-03-11

    In the present work, reduced graphene oxide (rGO)/poly(N-isopropylacrylamide) (PNIPAA) composite films were electrodeposited onto the surface of Au electrodes in a fast and one-step manner from an aqueous mixture of a graphene oxide (GO) dispersion and N-isopropylacrylamide (NIPAA) monomer solutions. Reflection-absorption infrared (IR) and Raman spectroscopies were employed to characterize the successful construction of the rGO/PNIPAA composite films. The rGO/PNIPAA composite films exhibited reversible potential-, pH-, temperature-, and sulfate-sensitive cyclic voltammetric (CV) on-off behavior to the electroactive probe ferrocenedicarboxylic acid (Fc(COOH)2). For instance, after the composite films were treated at -0.7 V for 7 min, the CV responses of Fc(COOH)2 at the rGO/PNIPAA electrodes were quite large at pH 8.0, exhibiting the on state. However, after the films were treated at 0 V for 30 min, the CV peak currents became much smaller, demonstrating the off state. The mechanism of the multiple-stimuli switchable behaviors for the system was investigated not only by electrochemical methods but also by scanning electron microscopy and X-ray photoelectron spectroscopy. The potential-responsive behavior for this system was mainly attributed to the transformation between rGO and GO in the films at different potentials. The film system was further used to realize multiple-stimuli responsive bioelectrocatalysis of glucose catalyzed by the enzyme of glucose oxidase and mediated by the electroactive probe of Fc(COOH)2 in solution. On the basis of this, a four-input enabled OR (EnOR) logic gate network was established.

  13. Relationship between the Increased Haemostatic Properties of Blood Platelets and Oxidative Stress Level in Multiple Sclerosis Patients with the Secondary Progressive Stage.

    PubMed

    Morel, Agnieszka; Bijak, Michał; Miller, Elżbieta; Rywaniak, Joanna; Miller, Sergiusz; Saluk, Joanna

    2015-01-01

    Multiple sclerosis (MS) is the autoimmune disease of the central nervous system with complex pathogenesis, different clinical courses and recurrent neurological relapses and/or progression. Despite various scientific papers that focused on early stage of MS, our study targets selective group of late stage secondary progressive MS patients. The presented work is concerned with the reactivity of blood platelets in primary hemostasis in SP MS patients. 50 SP MS patients and 50 healthy volunteers (never diagnosed with MS or other chronic diseases) were examined to evaluate the biological activity of blood platelets (adhesion, aggregation), especially their response to the most important physiological agonists (thrombin, ADP, and collagen) and the effect of oxidative stress on platelet activity. We found that the blood platelets from SP MS patients were significantly more sensitive to all used agonists in comparison with control group. Moreover, the platelet hemostatic function was advanced in patients suffering from SP MS and positively correlated with increased production of O2 (-∙) in these cells, as well as with Expanded Disability Status Scale. We postulate that the increased oxidative stress in blood platelets in SP MS may be primarily responsible for the altered haemostatic properties of blood platelets.

  14. Dose-dependent S-allyl cysteine ameliorates multiple sclerosis disease-related pathology by reducing oxidative stress and biomerkers of dysbiosis in experimental autoimmune encephalomyelitis.

    PubMed

    Escribano, B M; Luque, E; Aguilar-Luque, M; Feijóo, M; Caballero-Villarraso, J; Torres, L A; Ramirez, V; García-Maceira, F I; Agüera, E; Santamaria, A; Túnez, I

    2017-09-19

    Garlic is a component of the Mediterranean diet. S-allyl cysteine (SAC), the most common organosulphur present in garlic, possesses neuroprotective properties. This investigation was performed to evaluate the dose-dependent protective action of SAC on oxidative damage, inflammation and gut microbiota alterations biomarkers. Experimental autoimmune encephalomyelitis (EAE) as a model of multiple sclerosis (MS) was induced by the myelin oligodendrocyte glycoprotein (MOG), whose effects were quantified by examining the changes in: clinical score, lipid peroxidation products, carbonylated proteins, glutathione system, tumor necrosis factor alpha (TNFα), and lipopolysaccharide membrane bacteria (LPS). Our results reveal that MOG induces paralysis, oxidative damage and increases in LPS binding protein (LBP) and LPS levels. In this work, two doses of SAC were compared with two dose of N-acetyl cysteine (NAC). SAC was more effective than NAC and it prevented the harmful effects induced by MOG more effectively at the dose of 50mg/kg than that of 18mg/kg. Surprisingly, NAC increases LBP levels while SAC had not such negative effect. In conclusion the data show the ability of SAC to modify EAE evolution. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Relationship between the Increased Haemostatic Properties of Blood Platelets and Oxidative Stress Level in Multiple Sclerosis Patients with the Secondary Progressive Stage

    PubMed Central

    Bijak, Michał; Miller, Elżbieta; Miller, Sergiusz

    2015-01-01

    Multiple sclerosis (MS) is the autoimmune disease of the central nervous system with complex pathogenesis, different clinical courses and recurrent neurological relapses and/or progression. Despite various scientific papers that focused on early stage of MS, our study targets selective group of late stage secondary progressive MS patients. The presented work is concerned with the reactivity of blood platelets in primary hemostasis in SP MS patients. 50 SP MS patients and 50 healthy volunteers (never diagnosed with MS or other chronic diseases) were examined to evaluate the biological activity of blood platelets (adhesion, aggregation), especially their response to the most important physiological agonists (thrombin, ADP, and collagen) and the effect of oxidative stress on platelet activity. We found that the blood platelets from SP MS patients were significantly more sensitive to all used agonists in comparison with control group. Moreover, the platelet hemostatic function was advanced in patients suffering from SP MS and positively correlated with increased production of O2 −∙ in these cells, as well as with Expanded Disability Status Scale. We postulate that the increased oxidative stress in blood platelets in SP MS may be primarily responsible for the altered haemostatic properties of blood platelets. PMID:26064417

  16. Assembly and benign step-by-step post-treatment of oppositely charged reduced graphene oxides for transparent conductive thin films with multiple applications.

    PubMed

    Zhu, Jiayi; He, Junhui

    2012-06-07

    We report a new approach for the fabrication of flexible and transparent conducting thin films via the layer-by-layer (LbL) assembly of oppositely charged reduced graphene oxide (RGO) and the benign step-by-step post-treatment on substrates with a low glass-transition temperature, such as glass and poly(ethylene terephthalate) (PET). The RGO dispersions and films were characterized by means of atomic force microscopy, UV-visible absorption spectrophotometery, Raman spectroscopy, transmission electron microscopy, contact angle/interface systems and a four-point probe. It was found that the graphene thin films exhibited a significant increase in electrical conductivity after the step-by-step post-treatments. The graphene thin film on the PET substrate had a good conductivity retainability after multiple cycles (30 cycles) of excessively bending (bending angle: 180°), while tin-doped indium oxide (ITO) thin films on PET showed a significant decrease in electrical conductivity. In addition, the graphene thin film had a smooth surface with tunable wettability.

  17. Nitric oxide regulates cell survival in purified cultures of avian retinal neurons: involvement of multiple transduction pathways.

    PubMed

    Mejía-García, T A; Paes-de-Carvalho, R

    2007-01-01

    Nitric oxide (NO) is an important signaling molecule in the CNS, regulating neuronal survival, proliferation and differentiation. Here, we explored the mechanism by which NO, produced from the NO donor S-nitroso-acetyl-d-l-penicillamine (SNAP), exerts its neuroprotective effect in purified cultures of chick retinal neurons. Cultures prepared from 8-day-old chick embryo retinas and incubated for 24 h (1 day in culture, C1) were treated or not with SNAP, incubated for a further 72 h (up to 4 days in culture, C4), fixed, and the number of cells estimated, or processed for cell death estimation, by measuring the reduction of the metabolic dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Experimental cultures were run in parallel but were re-fed with fresh medium in the absence or presence of SNAP at culture day 3 (C3), incubated for a further 24 h up to C4, then fixed or processed for the MTT assay. Previous studies showed that the re-feeding procedure promotes extensive cell death. SNAP prevented this death in a concentration- and time-dependent manner through the activation of soluble guanylate cyclase; this protection was significantly reversed by the enzyme inhibitors 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) or LY83583, and mimicked by 8-bromo cyclic guanosine 5'-phosphate (8Br-cGMP) (GMP) or 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1), guanylate cyclase activators. The effect was blocked by the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). The effect of NO was also suppressed by LY294002, Wortmannin, PD98059, KN93 or H89, indicating the involvement, respectively, of phosphatidylinositol-3 kinase, extracellular-regulated kinases, calmodulin-dependent kinases and protein kinase A signaling pathways. NO also induced a significant increase of neurite outgrowth, indicative of neuronal differentiation, and blocked cell death induced by hydrogen peroxide. Cyclosporin A, an inhibitor of the

  18. The detectability of nitrous oxide mitigation efficacy in intensively grazed pastures using a multiple plot micrometeorological technique

    NASA Astrophysics Data System (ADS)

    McMillan, A. M. S.; Harvey, M. J.; Martin, R. J.; Bromley, A. M.; Evans, M. J.; Mukherjee, S.; Laubach, J.

    2013-10-01

    Methodologies are required to verify agricultural greenhouse gas mitigation at scales relevant to farm management. Micrometeorological techniques provide a viable approach for comparing fluxes between fields receiving mitigation treatments and control fields. However, they have rarely been applied to spatially verifying treatments aimed at mitigating nitrous oxide emission from intensively grazed pastoral systems. We deployed a micrometeorological system to compare N2O flux among several ~ 1.5 ha plots in intensively grazed dairy pasture. The sample collection and measurement system is referred to as the Field-Scale Nitrous Oxide Mitigation Assessment System (FS-NOMAS) and used a tuneable diode laser absorption spectrometer to measure N2O gradients to high precision at four locations along a 300 m transect. The utility of the FS-NOMAS to assess mitigation efficacy depends largely on its ability to resolve very small vertical N2O gradients. The performance of the FS-NOMAS was assessed in this respect in laboratory and field-based studies. The FS-NOMAS could reliably resolve gradients of 0.039 ppb between a height of 0.5 m and 1.0 m. The gradient resolution achieved corresponded to the ability to detect an inter-plot N2O flux difference of 26.4 μg N2O-N m-2 h-1 under the most commonly encountered conditions of atmospheric mixing (quantified here by a turbulent transfer coefficient), but this ranged from 11 to 59 μg N2O-N m-2 h-1 as the transfer coefficient ranged between its 5th and 95th percentile. Assuming a likely value of 100 μg N2O-N m-2 h-1 for post-grazing N2O fluxes from intensively grazed New Zealand dairy pasture, the system described here would be capable of detecting a mitigation efficacy of 26% for a single (40 min) comparison. We demonstrate that the system has considerably greater sensitivity to treatment effects by measuring cumulative fluxes over extended periods.

  19. The detectability of nitrous oxide mitigation efficacy in intensively grazed pastures using a multiple-plot micrometeorological technique

    NASA Astrophysics Data System (ADS)

    McMillan, A. M. S.; Harvey, M. J.; Martin, R. J.; Bromley, A. M.; Evans, M. J.; Mukherjee, S.; Laubach, J.

    2014-05-01

    Methodologies are required to verify agricultural greenhouse gas mitigation at scales relevant to farm management. Micrometeorological techniques provide a viable approach for comparing fluxes between fields receiving mitigation treatments and control fields. However, they have rarely been applied to spatially verifying treatments aimed at mitigating nitrous oxide emission from intensively grazed pastoral systems. We deployed a micrometeorological system to compare N2O flux among several ~1.5 ha plots in intensively grazed dairy pasture. The sample collection and measurement system is referred to as the Field-Scale Nitrous Oxide Mitigation Assessment System (FS-NOMAS) and used a tuneable diode laser absorption spectrometer to measure N2O gradients to high precision at four locations along a 300 m transect. The utility of the FS-NOMAS to assess mitigation efficacy depends largely on its ability to resolve very small vertical N2O gradients. The performance of the FS-NOMAS was assessed in this respect in laboratory and field-based studies. The FS-NOMAS could reliably resolve gradients of 0.039 ppb between a height of 0.5 and 1.0 m. The gradient resolution achieved corresponded to the ability to detect an inter-plot N2O flux difference of 26 μg N2O-N m-2 h-1 under the most commonly encountered conditions of atmospheric mixing (quantified here by a turbulent transfer coefficient), but this ranged from 11 to 59 μg N2O-N m-2 h-1 as the transfer coefficient ranged between its 5th and 95th percentile. Assuming a likely value of 100 μg N2O-N m-2 h-1 for post-grazing N2O fluxes from intensively grazed New Zealand dairy pasture, the system described here would be capable of detecting a mitigation efficacy of 26% for a single (40 min) comparison. We demonstrate that the system has considerably greater sensitivity to treatment effects by measuring cumulative fluxes over extended periods.

  20. Thiocyanate complexes of uranium in multiple oxidation states: a combined structural, magnetic, spectroscopic, spectroelectrochemical, and theoretical study.

    PubMed

    Hashem, Emtithal; Platts, James A; Hartl, František; Lorusso, Giulia; Evangelisti, Marco; Schulzke, Carola; Baker, Robert J

    2014-08-18

    A comprehensive study of the complexes A4[U(NCS)8] (A = Cs, Et4N, (n)Bu4N) and A3[UO2(NCS)5] (A = Cs, Et4N) is described, with the crystal structures of [(n)Bu4N]4[U(NCS)8]·2MeCN and Cs3[UO2(NCS)5]·O0.5 reported. The magnetic properties of square antiprismatic Cs4[U(NCS)8] and cubic [Et4N]4[U(NCS)8] have been probed by SQUID magnetometry. The geometry has an important impact on the low-temperature magnetic moments: at 2 K, μeff = 1.21 μB and 0.53 μB, respectively. Electronic absorption and photoluminescence spectra of the uranium(IV) compounds have been measured. The redox chemistry of [Et4N]4[U(NCS)8] has been explored using IR and UV-vis spectroelectrochemical methods. Reversible 1-electron oxidation of one of the coordinated thiocyanate ligands occurs at +0.22 V vs Fc/Fc(+), followed by an irreversible oxidation to form dithiocyanogen (NCS)2 which upon back reduction regenerates thiocyanate anions coordinating to UO2(2+). NBO calculations agree with the experimental spectra, suggesting that the initial electron loss of [U(NCS)8](4-) is delocalized over all NCS(-) ligands. Reduction of the uranyl(VI) complex [Et4N]3[UO2(NCS)5] to uranyl(V) is accompanied by immediate disproportionation and has only been studied by DFT methods. The bonding in [An(NCS)8](4-) (An = Th, U) and [UO2(NCS)5](3-) has been explored by a combination of DFT and QTAIM analysis, and the U-N bonds are predominantly ionic, with the uranyl(V) species more ionic that the uranyl(VI) ion. Additionally, the U(IV)-NCS ion is more ionic than what was found for U(IV)-Cl complexes.

  1. Z-Scan Analysis: a New Method to Determine the Oxidative State of Low-Density Lipoprotein and Its Association with Multiple Cardiometabolic Biomarkers

    NASA Astrophysics Data System (ADS)

    de Freitas, Maria Camila Pruper; Figueiredo Neto, Antonio Martins; Giampaoli, Viviane; da Conceição Quintaneiro Aubin, Elisete; de Araújo Lima Barbosa, Milena Maria; Damasceno, Nágila Raquel Teixeira

    2016-04-01

    The great atherogenic potential of oxidized low-density lipoprotein has been widely described in the literature. The objective of this study was to investigate whether the state of oxidized low-density lipoprotein in human plasma measured by the Z-scan technique has an association with different cardiometabolic biomarkers. Total cholesterol, high-density lipoprotein cholesterol, triacylglycerols, apolipoprotein A-I and apolipoprotein B, paraoxonase-1, and glucose were analyzed using standard commercial kits, and low-density lipoprotein cholesterol was estimated using the Friedewald equation. A sandwich enzyme-linked immunosorbent assay was used to detect electronegative low-density lipoprotein. Low-density lipoprotein and high-density lipoprotein sizes were determined by Lipoprint® system. The Z-scan technique was used to measure the non-linear optical response of low-density lipoprotein solution. Principal component analysis and correlations were used respectively to resize the data from the sample and test association between the θ parameter, measured with the Z-scan technique, and the principal component. A total of 63 individuals, from both sexes, with mean age 52 years (±11), being overweight and having high levels of total cholesterol and low levels of high-density lipoprotein cholesterol, were enrolled in this study. A positive correlation between the θ parameter and more anti-atherogenic pattern for cardiometabolic biomarkers together with a negative correlation for an atherogenic pattern was found. Regarding the parameters related with an atherogenic low-density lipoprotein profile, the θ parameter was negatively correlated with a more atherogenic pattern. By using Z-scan measurements, we were able to find an association between oxidized low-density lipoprotein state and multiple cardiometabolic biomarkers in samples from individuals with different cardiovascular risk factors.

  2. Effects of insulin combined with ethyl pyruvate on inflammatory response and oxidative stress in multiple-organ dysfunction syndrome rats with severe burns.

    PubMed

    Wang, Zhanke; Chen, Rongjian; Zhu, Zhongzhen; Zhang, Xiaoyun; Wang, Shiliang

    2016-11-01

    Inflammation response and oxidative stress promote the occurrence and development of multiple-organ dysfunction syndrome (MODS). Eighty MODS rats with third-degree burns were divided randomly into 4 groups: insulin, ethyl pyruvate (EP), insulin combined with EP, and control. Blood levels of glucose, alanine aminotransferase (ALT), creatine (CRE), creatine kinase (CK), tumor necrosis factor α (TNF-α), high-mobility group box 1 (HMGB-1), malondialdehyde (MDA), and total antioxidant capacity (TAC) before as well as 1, 3, 5, and 7 days after burns were measured. Blood levels of ALT, CRE, CK, TNF-α, HMGB-1, and MDA in INS, EP, and INS+EP groups at different time points were significantly lower, and TAC was significantly higher than that in the control group (C) (P<.01). These parameters in the INS+EP group were significantly lower, and TAC was significantly higher than that in INS and EP groups (P<.01). Blood levels of TNF-α, HMGB-1, and TAC in the INS group at different time points after burns were significantly lower, and MDA was significantly higher than that in the EP group (P<.01). Insulin combined with EP can effectively reduce the inflammatory response, oxidative stress, and main organ dysfunctions in MODS rats after severe burns. The therapeutic effect of insulin combined with EP is superior to single-agent treatment. The insulin anti-inflammatory effect is better than that of pyruvic acid ethyl ester, and the ethyl pyruvate antioxidation effect is better than that of insulin. The insulin can treat inflammation, whereas EP can reduce oxidative stress in MODS rats. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. In Situ Live Cell Sensing of Multiple Nucleotides Exploiting DNA/RNA Aptamers and Graphene Oxide Nanosheets

    SciTech Connect

    Wang, Ying; Li, Zhaohui; Weber, Thomas J.; Hu, Dehong; Lin, Chiann Tso; Li, Jinghong; Lin, Yuehe

    2013-07-23

    Adenosine-5’-triphosphate (ATP) and guanosine-5’-triphosphate (GTP) are primary energy resources and function coordinately for numerous reactions such as microtubule assembly, insulin secretion and ion channel regulation. We have developed a novel DNA/RNA aptamer- graphene oxide nanosheet (GO-nS) sensing platform that can selectively and simultaneously detect ATP and GTP in live cells. A fluorescent tag is covalently attached to aptamers and fluorescence is quenched upon binding of aptamer to the GO-nS. Fluorescently tagged aptamers that selectively bind ATP or GTP were isolated from an aptamer library and were adsorbed onto GO-nS. Upon incubation with targets (ATP and/or GTP), the aptamers readily dissociated from GO-nS and the fluorescent signal was recovered. By covalently attaching fluorophores, both ATP and GTP sensing aptamers could be exploited to simultaneously visualize aptamer dissociation in live cells. In addition, the GO-nS appear to be biocompatible and protect the adsorbed DNA/RNA aptamers from enzymatic cleavage. Our results support the application of aptamer/GO-nS as a sensing platform for nucleotides in living cells and have implications for the development of additional sensor platforms for other bio-molecules that show selective interactions with aptamers and other biomarkers.

  4. Multiple strategies to prevent oxidative stress in Arabidopsis plants lacking the malate valve enzyme NADP-malate dehydrogenase

    PubMed Central

    Hebbelmann, Inga; Selinski, Jennifer; Wehmeyer, Corinna; Goss, Tatjana; Voss, Ingo; Mulo, Paula; Kangasjärvi, Saijaliisa; Aro, Eva-Mari; Oelze, Marie-Luise; Dietz, Karl-Josef; Nunes-Nesi, Adriano; Do, Phuc T.; Fernie, Alisdair R.; Talla, Sai K.; Raghavendra, Agepati S.; Linke, Vera; Scheibe, Renate

    2012-01-01

    The nuclear-encoded chloroplast NADP-dependent malate dehydrogenase (NADP-MDH) is a key enzyme controlling the malate valve, to allow the indirect export of reducing equivalents. Arabidopsis thaliana (L.) Heynh. T-DNA insertion mutants of NADP-MDH were used to assess the role of the light-activated NADP-MDH in a typical C3 plant. Surprisingly, even when exposed to high-light conditions in short days, nadp-mdh knockout mutants were phenotypically indistinguishable from the wild type. The photosynthetic performance and typical antioxidative systems, such as the Beck–Halliwell–Asada pathway, were barely affected in the mutants in response to high-light treatment. The reactive oxygen species levels remained low, indicating the apparent absence of oxidative stress, in the mutants. Further analysis revealed a novel combination of compensatory mechanisms in order to maintain redox homeostasis in the nadp-mdh plants under high-light conditions, particularly an increase in the NTRC/2-Cys peroxiredoxin (Prx) system in chloroplasts. There were indications of adjustments in extra-chloroplastic components of photorespiration and proline levels, which all could dissipate excess reducing equivalents, sustain photosynthesis, and prevent photoinhibition in nadp-mdh knockout plants. Such metabolic flexibility suggests that the malate valve acts in concert with other NADPH-consuming reactions to maintain a balanced redox state during photosynthesis under high-light stress in wild-type plants. PMID:22140244

  5. Multiple strategies to prevent oxidative stress in Arabidopsis plants lacking the malate valve enzyme NADP-malate dehydrogenase.

    PubMed

    Hebbelmann, Inga; Selinski, Jennifer; Wehmeyer, Corinna; Goss, Tatjana; Voss, Ingo; Mulo, Paula; Kangasjärvi, Saijaliisa; Aro, Eva-Mari; Oelze, Marie-Luise; Dietz, Karl-Josef; Nunes-Nesi, Adriano; Do, Phuc T; Fernie, Alisdair R; Talla, Sai K; Raghavendra, Agepati S; Linke, Vera; Scheibe, Renate

    2012-02-01

    The nuclear-encoded chloroplast NADP-dependent malate dehydrogenase (NADP-MDH) is a key enzyme controlling the malate valve, to allow the indirect export of reducing equivalents. Arabidopsis thaliana (L.) Heynh. T-DNA insertion mutants of NADP-MDH were used to assess the role of the light-activated NADP-MDH in a typical C(3) plant. Surprisingly, even when exposed to high-light conditions in short days, nadp-mdh knockout mutants were phenotypically indistinguishable from the wild type. The photosynthetic performance and typical antioxidative systems, such as the Beck-Halliwell-Asada pathway, were barely affected in the mutants in response to high-light treatment. The reactive oxygen species levels remained low, indicating the apparent absence of oxidative stress, in the mutants. Further analysis revealed a novel combination of compensatory mechanisms in order to maintain redox homeostasis in the nadp-mdh plants under high-light conditions, particularly an increase in the NTRC/2-Cys peroxiredoxin (Prx) system in chloroplasts. There were indications of adjustments in extra-chloroplastic components of photorespiration and proline levels, which all could dissipate excess reducing equivalents, sustain photosynthesis, and prevent photoinhibition in nadp-mdh knockout plants. Such metabolic flexibility suggests that the malate valve acts in concert with other NADPH-consuming reactions to maintain a balanced redox state during photosynthesis under high-light stress in wild-type plants.

  6. Enhancement of the proline and nitric oxide synthetic pathway improves fermentation ability under multiple baking-associated stress conditions in industrial baker's yeast

    PubMed Central

    2012-01-01

    Background During the bread-making process, industrial baker's yeast, mostly Saccharomyces cerevisiae, is exposed to baking-associated stresses, such as air-drying and freeze-thaw stress. These baking-associated stresses exert severe injury to yeast cells, mainly due to the generation of reactive oxygen species (ROS), leading to cell death and reduced fermentation ability. Thus, there is a great need for a baker's yeast strain with higher tolerance to baking-associated stresses. Recently, we revealed a novel antioxidative mechanism in a laboratory yeast strain that is involved in stress-induced nitric oxide (NO) synthesis from proline via proline oxidase Put1 and N-acetyltransferase Mpr1. We also found that expression of the proline-feedback inhibition-less sensitive mutant γ-glutamyl kinase (Pro1-I150T) and the thermostable mutant Mpr1-F65L resulted in an enhanced fermentation ability of baker's yeast in bread dough after freeze-thaw stress and air-drying stress, respectively. However, baker's yeast strains with high fermentation ability under multiple baking-associated stresses have not yet been developed. Results We constructed a self-cloned diploid baker's yeast strain with enhanced proline and NO synthesis by expressing Pro1-I150T and Mpr1-F65L in the presence of functional Put1. The engineered strain increased the intracellular NO level in response to air-drying stress, and the strain was tolerant not only to oxidative stress but also to both air-drying and freeze-thaw stresses probably due to the reduced intracellular ROS level. We also showed that the resultant strain retained higher leavening activity in bread dough after air-drying and freeze-thaw stress than that of the wild-type strain. On the other hand, enhanced stress tolerance and fermentation ability did not occur in the put1-deficient strain. This result suggests that NO is synthesized in baker's yeast from proline in response to oxidative stresses that induce ROS generation and that increased NO

  7. Enhancement of the proline and nitric oxide synthetic pathway improves fermentation ability under multiple baking-associated stress conditions in industrial baker's yeast.

    PubMed

    Sasano, Yu; Haitani, Yutaka; Hashida, Keisuke; Ohtsu, Iwao; Shima, Jun; Takagi, Hiroshi

    2012-04-01

    During the bread-making process, industrial baker's yeast, mostly Saccharomyces cerevisiae, is exposed to baking-associated stresses, such as air-drying and freeze-thaw stress. These baking-associated stresses exert severe injury to yeast cells, mainly due to the generation of reactive oxygen species (ROS), leading to cell death and reduced fermentation ability. Thus, there is a great need for a baker's yeast strain with higher tolerance to baking-associated stresses. Recently, we revealed a novel antioxidative mechanism in a laboratory yeast strain that is involved in stress-induced nitric oxide (NO) synthesis from proline via proline oxidase Put1 and N-acetyltransferase Mpr1. We also found that expression of the proline-feedback inhibition-less sensitive mutant γ-glutamyl kinase (Pro1-I150T) and the thermostable mutant Mpr1-F65L resulted in an enhanced fermentation ability of baker's yeast in bread dough after freeze-thaw stress and air-drying stress, respectively. However, baker's yeast strains with high fermentation ability under multiple baking-associated stresses have not yet been developed. We constructed a self-cloned diploid baker's yeast strain with enhanced proline and NO synthesis by expressing Pro1-I150T and Mpr1-F65L in the presence of functional Put1. The engineered strain increased the intracellular NO level in response to air-drying stress, and the strain was tolerant not only to oxidative stress but also to both air-drying and freeze-thaw stresses probably due to the reduced intracellular ROS level. We also showed that the resultant strain retained higher leavening activity in bread dough after air-drying and freeze-thaw stress than that of the wild-type strain. On the other hand, enhanced stress tolerance and fermentation ability did not occur in the put1-deficient strain. This result suggests that NO is synthesized in baker's yeast from proline in response to oxidative stresses that induce ROS generation and that increased NO plays an important

  8. An RMND1 Mutation causes encephalopathy associated with multiple oxidative phosphorylation complex deficiencies and a mitochondrial translation defect.

    PubMed

    Janer, Alexandre; Antonicka, Hana; Lalonde, Emilie; Nishimura, Tamiko; Sasarman, Florin; Brown, Garry K; Brown, Ruth M; Majewski, Jacek; Shoubridge, Eric A

    2012-10-05

    Mutations in the genes composing the mitochondrial translation apparatus are an important cause of a heterogeneous group of oxidative phosphorylation (OXPHOS) disorders. We studied the index case in a consanguineous family in which two children presented with severe encephalopathy, lactic acidosis, and intractable seizures leading to an early fatal outcome. Blue native polyacrylamide gel electrophoretic (BN-PAGE) analysis showed assembly defects in all of the OXPHOS complexes with mtDNA-encoded structural subunits, and these defects were associated with a severe deficiency in mitochondrial translation. Immunoblot analysis showed reductions in the steady-state levels of several structural subunits of the mitochondrial ribosome. Whole-exome sequencing identified a homozygous missense mutation (c.1250G>A) in an uncharacterized gene, RMND1 (required for meiotic nuclear division 1). RMND1 localizes to mitochondria and behaves as an integral membrane protein. Retroviral expression of the wild-type RMND1 cDNA rescued the biochemical phenotype in subject cells, and siRNA-mediated knockdown of the protein recapitulated the defect. BN-PAGE, gel filtration, and mass spectrometry analyses showed that RMND1 forms a high-molecular-weight and most likely homopolymeric complex (∼240 kDa) that does not assemble in subject fibroblasts but that is rescued by expression of RMND1 cDNA. The p.Arg417Gln substitution, predicted to be in a coiled-coil domain, which is juxtaposed to a transmembrane domain at the extreme C terminus of the protein, does not alter the steady-state level of RMND1 but might prevent protein-protein interactions in this complex. Our results demonstrate that the RMND1 complex is necessary for mitochondrial translation, possibly by coordinating the assembly or maintenance of the mitochondrial ribosome. Copyright © 2012 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

  9. Nitric Oxide-cGMP Signaling Stimulates Erythropoiesis through Multiple Lineage-Specific Transcription Factors: Clinical Implications and a Novel Target for Erythropoiesis

    PubMed Central

    Ikuta, Tohru; Sellak, Hassan; Odo, Nadine; Adekile, Adekunle D.; Gaensler, Karin M. L.

    2016-01-01

    Much attention has been directed to the physiological effects of nitric oxide (NO)-cGMP signaling, but virtually nothing is known about its hematologic effects. We reported for the first time that cGMP signaling induces human γ-globin gene expression. Aiming at developing novel therapeutics for anemia, we examined here the hematologic effects of NO-cGMP signaling in vivo and in vitro. We treated wild-type mice with NO to activate soluble guanylate cyclase (sGC), a key enzyme of cGMP signaling. Compared to untreated mice, NO-treated mice had higher red blood cell counts and total hemoglobin but reduced leukocyte counts, demonstrating that when activated, NO-cGMP signaling exerts hematopoietic effects on multiple types of blood cells in vivo. We next generated mice which overexpressed rat sGC in erythroid and myeloid cells. The forced expression of sGCs activated cGMP signaling in both lineage cells. Compared with non-transgenic littermates, sGC mice exhibited hematologic changes similar to those of NO-treated mice. Consistently, a membrane-permeable cGMP enhanced the differentiation of hematopoietic progenitors toward erythroid-lineage cells but inhibited them toward myeloid-lineage cells by controlling multiple lineage-specific transcription factors. Human γ-globin gene expression was induced at low but appreciable levels in sGC mice carrying the human β-globin locus. Together, these results demonstrate that NO-cGMP signaling is capable of stimulating erythropoiesis in both in vitro and vivo settings by controlling the expression of multiple lineage-specific transcription factors, suggesting that cGMP signaling upregulates erythropoiesis at the level of gene transcription. The NO-cGMP signaling axis may constitute a novel target to stimulate erythropoiesis in vivo. PMID:26727002

  10. Multiple sulfur isotope constraints on sulfate-driven anaerobic oxidation of methane: Evidence from authigenic pyrite in seepage areas of the South China Sea

    NASA Astrophysics Data System (ADS)

    Lin, Zhiyong; Sun, Xiaoming; Strauss, Harald; Lu, Yang; Gong, Junli; Xu, Li; Lu, Hongfeng; Teichert, Barbara M. A.; Peckmann, Jörn

    2017-08-01

    Multiple sulfur isotope signatures and secondary ion mass spectroscopy (SIMS) sulfur isotope compositions of pyrite from two seafloor sites (DH-CL11 and HD109) in seepage areas of the South China Sea were measured in order to study isotope effects of sulfate-driven anaerobic oxidation of methane (SO4-AOM). The multiple sulfur isotopes of pyrite reveal variable ranges for both sites (δ34S: between -44.1‰ and -2.9‰ for DH-CL11 and between -43.8‰ and -1.6‰ for HD109; Δ33S: between 0.02‰ and 0.17‰ for DH-CL11 and between -0.03‰ and 0.14‰ for HD109). SIMS analysis reveals an extreme variability of δ34S values (between -50.3‰ and -2.7‰ in DH-CL11; between -50.1 and 52.4‰ in HD109) for three types of pyrite: (1) framboids, (2) zoned aggregates with radial overgrowth surrounding a framboidal core, and (3) euhedral pyrite crystals. The synchronous changes of geochemical proxies (sulfate and methane concentrations, δ34Ssulfate and δ18Osulfate, δ34Spyrite, and pyrite content) at the sulfate-methane transition zone (SMTZ) at site DH-CL11 are interpreted to be induced by SO4-AOM under steady state conditions. In contrast, pyrite content and δ34S value fluctuations throughout core HD109 suggest that the sediment at this site was affected by multiple pyritization events during diagenesis. Multiple sulfur isotope signatures of early diagenetic pyrite (i.e., with low and high δ34S values, the latter above 315 cmbsf in DH-CL11; above 70 cmbsf in HD109) in the upper sediment column suggest that organoclastic sulfate reduction (OSR) and sulfur disproportionation generated the observed isotopic signatures. In contrast to the early diagenetic 34S depleted framboids, the higher SIMS δ34S values of overgrowth and euhedral crystals suggest a late diagenetic 34S enriched pool of dissolved sulfide derived from SO4-AOM at the current and paleo-SMTZs. Interestingly, pyrite resulting from SO4-AOM in the SMTZ at site DH-CL11 reveals a distinct pattern with higher

  11. New Measurement of the Electron Magnetic Moment and the Fine Structure Constant: A First Application of a One-Electron Quantum Cyclotron

    ScienceCinema

    Gabrielse, Gerald [Harvard University, Cambridge, Massachusetts, United States

    2016-07-12

    Remarkably, the famous UW measurement of the electron magnetic moment has stood since 1987. With QED theory, this measurement has determined the accepted value of the fine structure constant. This colloquium is about a new Harvard measurement of these fundamental constants. The new measurement has an uncertainty that is about six times smaller, and it shifts the values by 1.7 standard deviations. One electron suspended in a Penning trap is used for the new measurement, like in the old measurement. What is different is that the lowest quantum levels of the spin and cyclotron motion are resolved, and the cyclotron as well as spin frequencies are determined using quantum jump spectroscopy. In addition, a 0.1 mK Penning trap that is also a cylindrical microwave cavity is used to control the radiation field, to suppress spontaneous emission by more than a factor of 100, to control cavity shifts, and to eliminate the blackbody photons that otherwise stimulate excitations from the cyclotron ground state. Finally, great signal-to-noise for one-quantum transitions is obtained using electronic feedback to realize the first one-particle self-excited oscillator. The new methods may also allow a million times improved measurement of the 500 times small antiproton magnetic moment.

  12. Quantum Switching of Magnetic Fields by Circularly Polarized Re-Optimized π Laser Pulses: From One-Electron Atomic Ions to Molecules

    NASA Astrophysics Data System (ADS)

    Barth, Ingo; Manz, Jörn

    Circularly polarized re-optimized π laser pulses may induce electronic and/or nuclear ring currents in model systems, from one-electron atomic ions till molecules which should have three-, four-, or higher-fold axes of rotations or reflection-rotations, in order to support doubly or more degenerate, complex-valued eigenstates which support these ring currents. The ring currents in turn induce magnetic fields. The effects are about two orders of magnitude larger than for traditional ring currents which are induced by external magnetic fields. Moreover, the laser pulses allow to control the strengths and shapes of the ring currents and, therefore, also the induced magnetic fields. We present a survey of the development of the field, together with new quantum simulations which document ultrafast switchings of magnetic fields. We discuss various criteria such as strong ring currents with small radii, in order to generate huge magnetic fields, approaching 1,000T, in accord with the Biot-Savart law. Moreover, we consider various methods for monitoring the fields, and for applications, in particular ultrafast deflections of neutrons by means of quantum switching of the ring currents and induced magnetic fields.

  13. Charge transfer in collisions of the effectively-one-electron isocharged ions Si3+, C3+, and O3+ with atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Guevara, N. L.; Teixeira, E.; Hall, B.; Öhrn, Y.; Deumens, E.; Sabin, J. R.

    2011-05-01

    In a recent paper [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.77.064702 77, 064702 (2008)], Bruhns reported on an experimental investigation of charge transfer in collisions of Si3+ ions with atomic hydrogen and compared the energy dependence of the transfer cross sections with published theoretical results and with earlier experimental results for other effectively-one-electron isocharged ions, including C3+ and O3+. These authors observe that these three ions all have the structure of a single electron outside a closed subshell and thus might be expected to behave similarly. However, their results show quite different behavior, and they conclude that the influence of quantum-mechanical effects from the ionic core is clearly seen. We have investigated theoretically three collision systems, Si3+, C3+, and O3+ with atomic hydrogen, at projectile energies up to 10 keV/amu using the method of electron nuclear dynamics (END). In this paper we want to clarify and describe in some detail these quantum-mechanical effects by showing the time-dependent dynamics of the electrons during the collision of these three ions with atomic hydrogen. Total charge transfer cross sections were calculated for all three ions and compared with other theoretical and experimental results, showing good overall agreement. With this validation of the END description of the processes, we analyze the details of the computed dynamics of the electrons in each of the processes and illustrate the different mechanisms underlying observed differences in reaction outcomes.

  14. Spiro- and dispiro-1,2-dioxolanes: contribution of iron(II)-mediated one-electron vs two-electron reduction to the activity of antimalarial peroxides.

    PubMed

    Wang, Xiaofang; Dong, Yuxiang; Wittlin, Sergio; Creek, Darren; Chollet, Jacques; Charman, Susan A; Tomas, Josefina Santo; Scheurer, Christian; Snyder, Christopher; Vennerstrom, Jonathan L

    2007-11-15

    Fourteen spiro- and dispiro-1,2-dioxolanes were synthesized by peroxycarbenium ion annulations with alkenes in yields ranging from 30% to 94%. Peroxycarbenium ion precursors included triethylsilyldiperoxyketals and -acetals derived from geminal dihydroperoxides and from a new method employing triethylsilylperoxyketals and -acetals derived from ozonolysis of alkenes. The 1,2-dioxolanes were either inactive or orders of magnitude less potent than the corresponding 1,2,4-trioxolanes or artemisinin against P. falciparum in vitro and P. berghei in vivo. In reactions with iron(II), the predominant reaction course for 1,2-dioxolane 3a was two-electron reduction. In contrast, the corresponding 1,2,4-trioxolane 1 and the 1,2,4-trioxane artemisinin undergo primarily one-electron iron(II)-mediated reductions. The key structural element in the latter peroxides appears to be an oxygen atom attached to one or both of the peroxide-bearing carbon atoms that permits rapid beta-scission reactions (or H shifts) to form primary or secondary carbon-centered radicals rather than further reduction of the initially formed Fe(III) complexed oxy radicals.

  15. Nonspherical Potential due to Orbital Polarization and Its Effect in Atoms —Approach to Hund’s Second Rule in Terms of One-Electron Picture—

    NASA Astrophysics Data System (ADS)

    Narita, Akira

    2008-12-01

    The exchange-correlation functional composed of the Xα-exchange energy and the new type of correlation energy EM is assumed in order to study the effect of the nonspherical spatial distribution of electrons and the degeneracy of the total energy for states with the different ML values in the electronic open-shell configuration lN (l = p,d) of atom, where N is the number of electrons in the open shell characterized by directional quantum number l, ML is an expectation value of the z-component Lz of total angular momentum, and EM depends on ML. Nonspherical quantities such as electron density and one-electron effective potential are made from the partially filled occupation obeying Hund’s first rule in the open shell, and the Kohn-Sham equation is solved by the self-consistent degenerate first-order perturbation theory. Then, the parameters included in EM are succinctly and conveniently determined by imposing the appropriate conditions of degeneracy on the orbital and total energies. These methods are applied to the first-row and 3d transition atoms. Numerically self-consistent results, in which the final occupied orbitals agree with the starting ones used for the construction of electron density, are obtained, and the energies are reasonably acceptable since the occupied orbitals are more low-lying than the empty ones. Furthermore, the degeneracy of total energy with respect to ML is also obtained.

  16. Solution of the Dirac equation using the Rayleigh-Ritz method: Flexible basis coupling large and small components. Results for one-electron systems

    NASA Astrophysics Data System (ADS)

    Baǧcı, A.; Hoggan, P. E.

    2016-07-01

    An algebraic solution of the Dirac equation is reinvestigated. Slater-type spinor orbitals and their corresponding system of differential equations are defined in two- and four-component formalism. They describe the radial function in components of the wave function of the Dirac equation solution to high accuracy. They constitute the matrix elements arising in a generalized eigenvalue equation. These terms are evaluated through prolate spheroidal coordinates. The corresponding integrals are calculated by the numerical global-adaptive method taking into account the Gauss-Kronrod numerical integration extension. Sample calculations are performed using flexible basis sets generated with both signs of the relativistic angular momentum quantum number κ . Applications to one-electron atoms and diatomics are detailed. Variationally optimum values for orbital parameters are obtained at given nuclear separation. Methods discussed in this work are capable of yielding highly accurate relativistic two-center integrals for all ranges of orbital parameters. This work provides an efficient way to overcome the problems that arise in relativistic calculations.

  17. Communication: Satisfying fermionic statistics in the modeling of open time-dependent quantum systems with one-electron reduced density matrices

    SciTech Connect

    Head-Marsden, Kade; Mazziotti, David A.

    2015-02-07

    For an open, time-dependent quantum system, Lindblad derived the most general modification of the quantum Liouville equation in the Markovian approximation that models environmental effects while preserving the non-negativity of the system’s density matrix. While Lindblad’s modification is correct for N-electron density matrices, solution of the Liouville equation with a Lindblad operator causes the one-electron reduced density matrix (1-RDM) to violate the Pauli exclusion principle. Consequently, after a short time, the 1-RDM is not representable by an ensemble N-electron density matrix (not ensemble N-representable). In this communication, we derive the necessary and sufficient constraints on the Lindbladian matrix within the Lindblad operator to ensure that the 1-RDM remains N-representable for all time. The theory is illustrated by considering the relaxation of an excitation in several molecules F{sub 2}, N{sub 2}, CO, and BeH{sub 2} subject to environmental noise.

  18. Real-time propagation of the reduced one-electron density matrix in atom-centered Gaussian orbitals: application to absorption spectra of silicon clusters.

    PubMed

    Sun, Jin; Song, Jian; Zhao, Yi; Liang, Wan-Zhen

    2007-12-21

    We solve the time-dependent density functional theory equation by propagating the reduced one-electron density matrix in real-time domain. The efficiency of several standard solvers such as the short-iterative Krylov-subspace propagator, the low-order Magnus integration method with the matrix polynomial (MP) or Chebyshev matrix polynomial (CMP) expansion of the evolution operator, and Runge-Kutta algorithm are assessed. Fast methods for summing MP and CMP are implemented to speed the calculation of the matrix exponential. It is found that the exponential propagators can tolerate large time step size and retain the computational accuracy whereas the Krylov-subspace algorithm is a little inferior for a larger time step size compared with the second-order Magnus integration method with the MP/CMP expansion of the evolution operator in both weak and intense fields. As an application, we calculate the absorption spectra of hydrogen-passivated silicon nanoparticles Si(29)H(x). The popular hybrid and generalized gradient approximation exchange-correlation functionals are applied. We find that the experimental spectra can be reproduced by using B3LYP and that the silicon particles with sizes of 1 nm and the optical excitations at 3.7, 4.0, and 4.6 eV may consist of 29 Si atoms surrounded by 24 hydrogen atoms.

  19. Solution of the Dirac equation using the Rayleigh-Ritz method: Flexible basis coupling large and small components. Results for one-electron systems.

    PubMed

    Bağcı, A; Hoggan, P E

    2016-07-01

    An algebraic solution of the Dirac equation is reinvestigated. Slater-type spinor orbitals and their corresponding system of differential equations are defined in two- and four-component formalism. They describe the radial function in components of the wave function of the Dirac equation solution to high accuracy. They constitute the matrix elements arising in a generalized eigenvalue equation. These terms are evaluated through prolate spheroidal coordinates. The corresponding integrals are calculated by the numerical global-adaptive method taking into account the Gauss-Kronrod numerical integration extension. Sample calculations are performed using flexible basis sets generated with both signs of the relativistic angular momentum quantum number κ. Applications to one-electron atoms and diatomics are detailed. Variationally optimum values for orbital parameters are obtained at given nuclear separation. Methods discussed in this work are capable of yielding highly accurate relativistic two-center integrals for all ranges of orbital parameters. This work provides an efficient way to overcome the problems that arise in relativistic calculations.

  20. One-electron spectra and susceptibilities of the three-dimensional electron gas from self-consistent solutions of Hedin's equations

    NASA Astrophysics Data System (ADS)

    Kutepov, A. L.; Kotliar, G.

    2017-07-01

    A few approximate schemes to solve the Hedin equations self-consistently introduced in Phys. Rev. B 94, 155101 (2016), 10.1103/PhysRevB.94.155101 are explored and tested for the three-dimensional (3D) electron gas at metallic densities. We calculate one-electron spectra, dielectric properties, compressibility, and correlation energy. Considerable reduction in the calculated bandwidth (as compared to the self-consistent G W result) has been found when vertex correction was used for both polarizability and self-energy. Generally, it is advantageous to obtain the diagrammatic representation of polarizability from the definition of this quantity as a functional derivative of the electronic density with respect to the total field (external plus induced). For self-energy, the first-order vertex correction seems to be sufficient for the range of densities considered. Whenever it is possible, we compare the accuracy of our vertex-corrected schemes with the accuracy of the self-consistent quasiparticle G W approximation (QSGW), which is less expensive computationally. We show that the QSGW approach performs poorly and we relate this poor performance with an inaccurate description of the screening in the QSGW method (with an error comprising a factor 2-3 in the physically important range of momenta).

  1. Secondary coenzyme Q10 deficiency and oxidative stress in cultured fibroblasts from patients with riboflavin responsive multiple Acyl-CoA dehydrogenation deficiency.

    PubMed

    Cornelius, Nanna; Byron, Colleen; Hargreaves, Iain; Guerra, Paula Fernandez; Furdek, Andrea K; Land, John; Radford, Weston W; Frerman, Frank; Corydon, Thomas J; Gregersen, Niels; Olsen, Rikke K J

    2013-10-01

    Coenzyme Q10 (CoQ10) is essential for the energy production of the cells and as an electron transporter in the mitochondrial respiratory chain. CoQ10 links the mitochondrial fatty acid β-oxidation to the respiratory chain by accepting electrons from electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO). Recently, it was shown that a group of patients with the riboflavin responsive form of multiple acyl-CoA dehydrogenation deficiency (RR-MADD) carrying inherited amino acid variations in ETF-QO also had secondary CoQ10 deficiency with beneficial effects of CoQ10 treatment, thus adding RR-MADD to an increasing number of diseases involving secondary CoQ10 deficiency. In this study, we show that moderately decreased CoQ10 levels in fibroblasts from six unrelated RR-MADD patients were associated with increased levels of mitochondrial reactive oxygen species (ROS). Treatment with CoQ10, but not with riboflavin, could normalize the CoQ10 level and decrease the level of ROS in the patient cells. Additionally, riboflavin-depleted control fibroblasts showed moderate CoQ10 deficiency, but not increased mitochondrial ROS, indicating that variant ETF-QO proteins and not CoQ10 deficiency are the causes of mitochondrial ROS production in the patient cells. Accordingly, the corresponding variant Rhodobacter sphaeroides ETF-QO proteins, when overexpressed in vitro, bind a CoQ10 pseudosubstrate, Q10Br, less tightly than the wild-type ETF-QO protein, suggesting that molecular oxygen can get access to the electrons in the misfolded ETF-QO protein, thereby generating superoxide and oxidative stress, which can be reversed by CoQ10 treatment.

  2. One-electron versus electron-electron interaction contributions to the spin-spin coupling mechanism in nuclear magnetic resonance spectroscopy: analysis of basic electronic effects.

    PubMed

    Gräfenstein, Jürgen; Cremer, Dieter

    2004-12-22

    For the first time, the nuclear magnetic resonance (NMR) spin-spin coupling mechanism is decomposed into one-electron and electron-electron interaction contributions to demonstrate that spin-information transport between different orbitals is not exclusively an electron-exchange phenomenon. This is done using coupled perturbed density-functional theory in conjunction with the recently developed J-OC-PSP [=J-OC-OC-PSP: Decomposition of J into orbital contributions using orbital currents and partial spin polarization)] method. One-orbital contributions comprise Ramsey response and self-exchange effects and the two-orbital contributions describe first-order delocalization and steric exchange. The two-orbital effects can be characterized as external orbital, echo, and spin transport contributions. A relationship of these electronic effects to zeroth-order orbital theory is demonstrated and their sign and magnitude predicted using simple models and graphical representations of first order orbitals. In the case of methane the two NMR spin-spin coupling constants result from totally different Fermi contact coupling mechanisms. (1)J(C,H) is the result of the Ramsey response and the self-exchange of the bond orbital diminished by external first-order delocalization external one-orbital effects whereas (2)J(H,H) spin-spin coupling is almost exclusively mitigated by a two-orbital steric exchange effect. From this analysis, a series of prediction can be made how geometrical deformations, electron lone pairs, and substituent effects lead to a change in the values of (1)J(C,H) and (2)J(H,H), respectively, for hydrocarbons.

  3. Coordinated and reversible reduction of enzymes involved in terminal oxidative metabolism in skeletal muscle mitochondria from a riboflavin-responsive, multiple acyl-CoA dehydrogenase deficiency patient.

    PubMed

    Gianazza, Elisabetta; Vergani, Lodovica; Wait, Robin; Brizio, Carmen; Brambilla, Daniela; Begum, Shajna; Giancaspero, Teresa A; Conserva, Francesca; Eberini, Ivano; Bufano, Daniela; Angelini, Corrado; Pegoraro, Elena; Tramontano, Anna; Barile, Maria

    2006-03-01

    In this case report we studied alterations in mitochondrial proteins in a patient suffering from recurrent profound muscle weakness, associated with ethylmalonic-adipic aciduria, who had benefited from high dose of riboflavin treatment. Morphological and biochemical alterations included muscle lipid accumulation, low muscle carnitine content, reduction in fatty acid beta-oxidation and reduced activity of complexes I and II of the respiratory chain. Riboflavin therapy partially or totally reversed these symptoms and increased the level of muscle flavin adenine dinucleotide, suggesting that aberrant flavin cofactor metabolism accounted for the disease. Proteomic investigation of muscle mitochondria revealed decrease or absence of several flavoenzymes, enzymes related to flavin cofactor-dependent mitochondrial pathways and mitochondrial or mitochondria-associated calcium-binding proteins. All these deficiencies were completely rescued after riboflavin treatment. This study indicates for the first time a profound involvement of riboflavin/flavin cofactors in modulating the level of a number of functionally coordinated polypeptides involved in fatty acyl-CoA and amino acid metabolism, extending the number of enzymatic pathways altered in riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency.

  4. Nitrosylation of Nitric-Oxide-Sensing Regulatory Proteins Containing [4Fe-4S] Clusters Gives Rise to Multiple Iron-Nitrosyl Complexes

    SciTech Connect

    Serrano, Pauline N.; Wang, Hongxin; Crack, Jason; Prior, Christopher; Hutchings, Matthew; Thompson, Andrew; Kamali, Seed; Yoda, Yoshitaka; Zhao, Jiyong; Hu, Michael; Alp, Ercan E.; Oganesyan, Vasily; Le Brun, Nick

    2016-11-14

    The reaction of protein-bound iron–sulfur (Fe-S) clusters with nitric oxide (NO) plays key roles in NO-mediated toxicity and signaling. Elucidation of the mechanism of the reaction of NO with DNA regulatory proteins that contain Fe-S clusters has been hampered by a lack of information about the nature of the iron-nitrosyl products formed. Herein, we report nuclear resonance vibrational spectroscopy (NRVS) and density functional theory (DFT) calculations that identify NO reaction products in WhiD and NsrR, regulatory proteins that use a [4Fe-4S] cluster to sense NO. This work reveals that nitrosylation yields multiple products structurally related to Roussin's Red Ester (RRE, [Fe2(NO)4(Cys)2]) and Roussin's Black Salt (RBS, [Fe4(NO)7S3]. In the latter case, the absence of 32S/34S shifts in the Fe−S region of the NRVS spectra suggest that a new species, Roussin's Black Ester (RBE), may be formed, in which one or more of the sulfide ligands is replaced by Cys thiolates.

  5. Effects of green tea extract and α-tocopherol on the lipid oxidation rate of omega-3 oils, incorporated into table spreads, prepared using multiple emulsion technology.

    PubMed

    Dwyer, Sandra P O'; O'Beirne, David; Ní Eidhin, Deirdre; O'Kennedy, Brendan T

    2012-12-01

    This study examined the effectiveness of fat and water soluble antioxidants on the oxidative stability of omega (ω)-3 rich table spreads, produced using novel multiple emulsion technology. Table spreads were produced by dispersing an oil-in-water (O/W) emulsion (500 g/kg 85 camelina/15 fish oil blend) in a hardstock/rapeseed oil blend, using sodium caseinate and polyglycerol polyricinoleate as emulsifiers. The O/W and oil-in-water-in-oil (O/W/O) emulsions contained either a water soluble antioxidant (green tea extract [GTE]), an oil soluble antioxidant (α-Tocopherol), or both. Spreads containing α-Tocopherol had the highest lipid hydroperoxide values, whereas spreads containing GTE had the lowest (P < 0.05), during storage at 5°C, while p-Anisidine values did not differ significantly. Particle size was generally unaffected by antioxidant type (P < 0.05). Double emulsion (O/W/O) structures were clearly seen in confocal images of the spreads. By the end of storage, none of the spreads had significantly different G' values. Firmness (Newtons) of all spreads generally increased during storage (P < 0.05). © 2012 Institute of Food Technologists®

  6. One-electron reduction of tris(2,2 prime -bipyrimidine)ruthenium(2+) ion in aqueous solution. A photochemical, radiation chemical, and electrochemical study

    SciTech Connect

    Neshvad, G.; Hoffman, M.Z. ); Mulazzani, Q.G.; Ciano, M.; D'Angelantonio, M. ); Venturi, M. Univ. di Bologna )

    1989-08-10

    The reduction of Ru(bpm){sub 3}{sup 2+} in aqueous solution has been investigated by use of photochemical, radiation chemical, and electrochemical techniques. The luminescent excited state of the substrate, *Ru(bpm){sub 3}{sup 2+}, has a lifetime ({tau}{sub 0}) of 0.081 {mu}s and a standard reduction potential of {approximately} 1.2 V; it is quenched by electron donors (D) such as ethylenediaminetetraacetic acid (EDTA), triethanolamine (TEOA), ascorbate ion, deprotonated cysteine, and reduced glutathione with values of k{sub q} that depend on the pH of the solution and the reducing ability of the quencher. The one-electron-reduced species, Ru(bpm){sub 3}{sup +}, is formed in the quenching reaction; it is also produced electrochemically and from the reaction of radiolytically generated CO{sub 2}{sup {center dot}{minus}} with Ru(bpm){sub 3}{sup 2+} (k = 6.7 {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1}). Ru(bpm){sub 3}{sup +} is a good reducing agent (E{sub ox}{sup 0} = 0.73 V) and reduces MV{sup 2+} (methylviologen) to MV{sup {center dot}+} (k = 1.0 {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1}). Ru(bpm){sub 3}{sup +} also undergoes protonation; its acidic form (pK{sub a} 6.3) is a milder reducing agent (E{sub ox}{sup 0} = 0.50 V) but is still capable of reducing MV{sup 2+} (k = 1.0 {times} 10{sup 6} M{sup {minus}1} s{sup {minus}1}). Both forms of Ru(bpm){sub 3}{sup +} are unstable with respect to long-term storage; it is likely they engage in disproportionation and/or reaction with the solvent. The continuous photolysis of a solution containing Ru(bpm){sub 3}{sup 2+}, MV{sup 2+}, and a sacrificial reductive quencher (EDTA, TEOA) generates MV{sup {center dot}+}. Values of {eta}{sub ce} of 0.64 and {approximately}0.7 for TEOA and EDTA, respectively, in alkaline solution have been obtained.

  7. Immune-Inflammatory and Oxidative and Nitrosative Stress Biomarkers of Depression Symptoms in Subjects with Multiple Sclerosis: Increased Peripheral Inflammation but Less Acute Neuroinflammation.

    PubMed

    Kallaur, Ana Paula; Lopes, Josiane; Oliveira, Sayonara Rangel; Simão, Andrea Name Colado; Reiche, Edna Maria Vissoci; de Almeida, Elaine Regina Delicato; Morimoto, Helena Kaminami; de Pereira, Wildea Lice Carvalho Jennings; Alfieri, Daniele Frizon; Borelli, Sueli Donizete; Kaimen-Maciel, Domacio Ramon; Maes, Michael

    2016-10-01

    There is evidence that activated immune-inflammatory and oxidative and nitrosative stress (IO&NS) pathways play a role in the pathophysiology of multiple sclerosis (MS) and depression. This study examines serum levels of interleukin (IL)-1β, IL-4, IL-6, and IL-10; peroxides (LOOH); nitric oxide metabolites (NOx); albumin; ferritin; C-reactive protein (CRP); and tumor necrosis factor (TNF)-β NcoI polymorphism (rs909253) and gadolinium-enhanced magnetic resonance imaging (MRI) scan in MS patients with (n = 42) and without (n = 108) depression and normal controls (n = 249). Depression is scored using the depressive subscale of the Hospital Anxiety and Depression Scale (HADS). The extent of neurological disability is measured using the Expanded Disability Status Scale (EDSS) at the same time of the abovementioned measurements and 5 years earlier. Disease progression is assessed as actual EDSS-EDSS 5 years earlier. Three variables discriminate MS patients with depression from those without depression, i.e., increased IL-6 and lower IL-4 and albumin. Binary logistic regression showed that MS with depression (versus no depression) was characterized by more gastrointestinal symptoms and disease progression, higher serum IL-6, and lower albumin levels. In subjects with MS, the HADS score was significantly predicted by three EDSS symptoms, i.e., pyramidal, gastrointestinal, and visual symptoms. Fifty-eight percent of the variance in the HADS score was predicted by gastrointestinal symptoms, visual symptoms, the TNFB1/B2 genotype, and contrast enhancement (both inversely associated). There were no significant associations between depression in MS and type of MS, duration of illness, age, sex, nicotine dependence, and body mass index. MS with depression is associated with signs of peripheral inflammation, more disability, disease progression, gastrointestinal and visual symptoms, but less contrast enhancement as compared to MS without depression. It is

  8. Concerted One-Electron Two-Proton Transfer Processes in Models Inspired by the Tyr-His Couple of Photosystem II

    DOE PAGES

    Huynh, Mioy T.; Mora, S. Jimena; Villalba, Matias; ...

    2017-05-09

    Nature employs a TyrZ-His pair as a redox relay that couples proton transfer to the redox process between P680 and the water oxidizing catalyst in photosystem II. Artificial redox relays composed of different benzimidazole–phenol dyads (benzimidazole models His and phenol models Tyr) with substituents designed to simulate the hydrogen bond network surrounding the TyrZ-His pair have been prepared. Furthermore, when the benzimidazole substituents are strong proton acceptors such as primary or tertiary amines, theory predicts that a concerted two proton transfer process associated with the electrochemical oxidation of the phenol will take place. Furthermore, theory predicts a decrease in themore » redox potential of the phenol by ~300 mV and a small kinetic isotope effect (KIE). Indeed, electrochemical, spectroelectrochemical, and KIE experimental data are consistent with these predictions. Our results were obtained by using theory to guide the rational design of artificial systems and have implications for managing proton activity to optimize efficiency at energy conversion sites involving water oxidation and reduction.« less

  9. Chemopreventive efficacy of hesperidin against chemically induced nephrotoxicity and renal carcinogenesis via amelioration of oxidative stress and modulation of multiple molecular pathways.

    PubMed

    Siddiqi, Aisha; Hasan, Syed Kazim; Nafees, Sana; Rashid, Summya; Saidullah, Bano; Sultana, Sarwat

    2015-12-01

    In the present study, chemopreventive efficacy of hesperidin was evaluated against ferric nitrilotriacetate (Fe-NTA) induced renal oxidative stress and carcinogenesis in wistar rats. Nephrotoxicity was induced by single intraperitoneal injection of Fe-NTA (9 mg Fe/kg b.wt). Renal cancer was initiated by the administration of N-nitrosodiethylamine (DEN 200mg/kg b.wt ip) and promoted by Fe-NTA (9 mg Fe/kg b.wt ip) twice weekly for 16 weeks. Efficacy of hesperidin against Fe-NTA-induced nephrotoxicity was assessed in terms of biochemical estimation of antioxidant enzyme activities viz. reduced renal GSH, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, catalase, superoxide dismutase and renal toxicity markers (BUN, Creatinine, KIM-1). Administration of Fe-NTA significantly depleted antioxidant renal armory, enhanced renal lipid peroxidation as well as the levels of BUN, creatinine and KIM-1. However, simultaneous pretreatment of hesperidin restored their levels in a dose dependent manner. Expression of apoptotic markers caspase-3, caspase-9, bax, bcl-2 and proliferative marker PCNA along with inflammatory markers (NFκB, iNOS, TNF-α) were also analysed to assess the chemopreventive potential of hesperidin in two-stage renal carcinogenesis model. Hesperidin was found to induce caspase-3, caspase-9, bax expression and downregulate bcl-2, NFκB, iNOS, TNF-α, PCNA expression. Histopathological findings further revealed hesperidin's chemopreventive efficacy by restoring the renal morphology. Our results provide a powerful evidence suggesting hesperidin to be a potent chemopreventive agent against renal carcinogenesis possibly by virtue of its antioxidant properties and by modulation of multiple molecular pathways.

  10. Acute paraquat exposure determines dose-dependent oxidative injury of multiple organs and metabolic dysfunction in rats: impact on exercise tolerance.

    PubMed

    Novaes, Rômulo D; Gonçalves, Reggiani V; Cupertino, Marli C; Santos, Eliziária C; Bigonha, Solange M; Fernandes, Geraldo J M; Maldonado, Izabel R S C; Natali, Antônio J

    2016-04-01

    This study investigated the pathological morphofunctional adaptations related to the imbalance of exercise tolerance triggered by paraquat (PQ) exposure in rats. The rats were randomized into four groups with eight animals each: (a) SAL (control): 0.5 ml of 0.9% NaCl solution; (b) PQ10: PQ 10 mg/kg; (c) PQ20: PQ 20 mg/kg; and (d) PQ30: PQ 30 mg/kg. Each group received a single injection of PQ. After 72 hours, the animals were subjected to an incremental aerobic running test until fatigue in order to determine exercise tolerance, blood glucose and lactate levels. After the next 24 h, lung, liver and skeletal muscle were collected for biometric, biochemical and morphological analyses. The animals exposed to PQ exhibited a significant anticipation of anaerobic metabolism during the incremental aerobic running test, a reduction in exercise tolerance and blood glucose levels as well as increased blood lactate levels during exercise compared to control animals. PQ exposure increased serum transaminase levels and reduced the glycogen contents in liver tissue and skeletal muscles. In the lung, the liver and the skeletal muscle, PQ exposure also increased the contents of malondialdehyde, protein carbonyl, 8-hydroxy-2'-deoxyguanosine, superoxide dismutase and catalase, as well as a structural remodelling compared to the control group. All these changes were dose-dependent. Reduced exercise tolerance after PQ exposure was potentially influenced by pathological remodelling of multiple organs, in which glycogen depletion in the liver and skeletal muscle and the imbalance of glucose metabolism coexist with the induction of lipid, protein and DNA oxidation, a destructive process not counteracted by the upregulation of endogenous antioxidant enzymes. © 2016 The Authors. International Journal of Experimental Pathology © 2016 International Journal of Experimental Pathology.

  11. Graphene oxide@gold nanorods-based multiple-assisted electrochemiluminescence signal amplification strategy for sensitive detection of prostate specific antigen.

    PubMed

    Cao, Jun-Tao; Yang, Jiu-Jun; Zhao, Li-Zhen; Wang, Yu-Ling; Wang, Hui; Liu, Yan-Ming; Ma, Shu-Hui

    2018-01-15

    A novel and competitive electrochemiluminescence (ECL) aptasensor for prostate specific antigen (PSA) assay was constructed using gold nanorods functionalized graphene oxide (GO@AuNRs) multilabeled with glucose oxidase (GOD) and streptavidin (SA) toward luminol-based ECL system. A strong initial ECL signal was achieved by electrodeposited gold (DpAu) on the electrode because of gold nanoparticles (AuNPs) motivating the luminol ECL signal. The signal probes prepared by loading GOD and SA-biotin-DNA on GO@AuNRs were used for achieving multiple signal amplification. In the absence of PSA, the signal probes can be attached on the electrode by hybridization reaction between PSA aptamer and biotin-DNA. In this state, the GOD loaded on the probe could catalyze glucose to in situ produce H2O2 and then AuNRs catalyze H2O2 to generate abundant reactive oxygen species (ROSs) in luminol ECL reaction. Both the high-content GOD and AuNRs in the signal probe amplified the ECL signal in the ECL system. Moreover, the combination of SA with biotin-DNA further expands ECL intensity. The integration of such amplifying effects in this protocol endows the aptasensor with high sensitivity and good selectivity for PSA detection. This aptasensor exhibits a linear relation in the range of 0.5pgmL(-1) to 5.0ngmL(-1) with the detection limit of 0.17pgmL(-1) (S/N = 3). Besides, the strategy was successfully applied in determination of human serum samples with recovery of 81.4-116.0%. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Timing of multiple hydrothermal events in the iron oxide-copper-gold deposits of the Southern Copper Belt, Carajás Province, Brazil

    NASA Astrophysics Data System (ADS)

    Moreto, Carolina P. N.; Monteiro, Lena V. S.; Xavier, Roberto P.; Creaser, Robert A.; DuFrane, S. Andrew; Melo, Gustavo H. C.; Delinardo da Silva, Marco A.; Tassinari, Colombo C. G.; Sato, Kei

    2015-06-01

    The Southern Copper Belt, Carajás Province, Brazil, hosts several iron oxide-copper-gold (IOCG) deposits, including Sossego, Cristalino, Alvo 118, Bacuri, Bacaba, Castanha, and Visconde. Mapping and U-Pb sensitive high-resolution ion microprobe (SHRIMP) IIe zircon geochronology allowed the characterization of the host rocks, situated within regional WNW-ESE shear zones. They encompass Mesoarchean (3.08-2.85 Ga) TTG orthogneiss, granites, and remains of greenstone belts, Neoarchean (ca. 2.74 Ga) granite, shallow-emplaced porphyries, and granophyric granite coeval with gabbro, and Paleoproterozoic (1.88 Ga) porphyry dykes. Extensive hydrothermal zones include albite-scapolite, biotite-scapolite-tourmaline-magnetite alteration, and proximal potassium feldspar, chlorite-epidote and chalcopyrite formation. U-Pb laser ablation multicollector inductively coupled mass spectrometry (LA-MC-ICP-MS) analysis of ore-related monazite and Re-Os NTIMS analysis of molybdenite suggest multiple Neoarchean (2.76 and 2.72-2.68 Ga) and Paleoproterozoic (2.06 Ga) hydrothermal events at the Bacaba and Bacuri deposits. These results, combined with available geochronological data from the literature, indicate recurrence of hydrothermal systems in the Southern Copper Belt, including 1.90-1.88-Ga ore formation in the Sossego-Curral ore bodies and the Alvo 118 deposit. Although early hydrothermal evolution at 2.76 Ga points to fluid migration coeval with the Carajás Basin formation, the main episode of IOCG genesis (2.72-2.68 Ga) is related to basin inversion coupled with Neoarchean (ca. 2.7 Ga) felsic magmatism. The data suggest that the IOCG deposits in the Southern Copper Belt and those in the Northern Copper Belt (2.57-Ga Salobo and Igarapé Bahia-Alemão deposits) do not share a common metallogenic evolution. Therefore, the association of all IOCG deposits of the Carajás Province with a single extensive hydrothermal system is precluded.

  13. Guanine oxidation by electron transfer: one- versus two-electron oxidation mechanism.

    PubMed

    Kupan, Adam; Saulière, Aude; Broussy, Sylvain; Seguy, Christel; Pratviel, Geneviève; Meunier, Bernard

    2006-01-01

    The degeneracy of the guanine radical cation, which is formed in DNA by oxidation of guanine by electron transfer, was studied by a detailed analysis of the oxidation products of guanine on oligonucleotide duplexes and by labeling experiments. It was shown that imidazolone, the major product of guanine oxidation, is formed through a one-electron oxidation process and incorporates one oxygen atom from O2. The formation of 8-oxo-7,8-dihydroguanine by a two-electron oxidation process was a minor pathway. The two-electron oxidation mechanism was also evidenced by the formation of a tris(hydroxymethyl)aminomethane adduct.

  14. Multiple Pregnancy

    MedlinePlus

    ... Education & Events Advocacy For Patients About ACOG Multiple Pregnancy Home For Patients Search FAQs Multiple Pregnancy Page ... Multiple Pregnancy FAQ188, July 2015 PDF Format Multiple Pregnancy Pregnancy How does multiple pregnancy occur? What are ...

  15. Electrochemical oxidation of methylenedioxyamphetamines.

    PubMed

    Squella, J A; Cassels, B K; Arata, M; Bavestrello, M P; Nuñez-Vergara, L J

    1993-09-01

    Four amphetamine derivatives bearing a methylenedioxy group at positions 3 and 4 of the benzene ring and differing in their substitution at C(6) were studied by differential pulse voltammetry in aqueous media. These experiments showed a single oxidation peak for the C(6)-H, -Br and -Cl compounds, while the C(6)-NO(2) analogue was not oxidized. The oxidation peak is interpreted as due to the removal of one electron from the aromatic electrophore with formation of a radical cation stabilized by the dioxole ring. The linear relationship between the peak current and the concentration of the derivatives is appropriate for development of a quantitative method for their determination. pK' values were determined using both electrochemical and spectrophotometric methods.

  16. Multiple protective mechanisms of alpha-lipoic acid in oxidation, apoptosis and inflammation against hydrogen peroxide induced toxicity in human lymphocytes.

    PubMed

    Rahimifard, Mahban; Navaei-Nigjeh, Mona; Baeeri, Maryam; Maqbool, Faheem; Abdollahi, Mohammad

    2015-05-01

    The naturally antioxidant and coenzyme, alpha-lipoic acid (α-LA), has gained considerable attention regarding different functions and therapeutically effective in treating oxidative stress-associated diseases in the human body. This study was designed to examine the protective effect of α-LA against H2O2-induced oxidative stress and apoptosis in human lymphoid cells. Human peripheral blood lymphocytes were preincubated with α-LA and then exposed to H2O2. After that, the viability of the cells, rate of apoptosis, oxidative stress biomarkers such as reactive oxygen species (ROS) and level of lipid peroxidation (LPO), and also tumor necrosis factor-α (TNF-α) were studied. Pretreatment of lymphocytes with α-LA, dramatically enhanced viability of the cells and decreased apoptosis. Investigation of caspases gives a clear picture of the mechanism by which α-LA decreases ROS and causes a reduction in apoptosis through caspase-9-dependent mitochondrial pathway. Furthermore, α-LA dose dependently decreased oxidative stress by a reduction in level of LPO, and the dose of 1000 µM indicates a significant decrease (p < 0.01) in TNF-α level. Collectively, the present data show that α-LA is an ideal compound which has profound protective effects on oxidation, inflammation, and apoptosis. As a result, α-LA may indicate a new way toward the development of antioxidant therapy.

  17. Multiple Low-Dose Radiation Prevents Type 2 Diabetes-Induced Renal Damage through Attenuation of Dyslipidemia and Insulin Resistance and Subsequent Renal Inflammation and Oxidative Stress

    PubMed Central

    Shao, Minglong; Lu, Xuemian; Cong, Weitao; Xing, Xiao; Tan, Yi; Li, Yunqian; Li, Xiaokun; Jin, Litai; Wang, Xiaojie; Dong, Juancong; Jin, Shunzi; Zhang, Chi; Cai, Lu

    2014-01-01

    Background Dyslipidemia and lipotoxicity-induced insulin resistance, inflammation and oxidative stress are the key pathogeneses of renal damage in type 2 diabetes. Increasing evidence shows that whole-body low dose radiation (LDR) plays a critical role in attenuating insulin resistance, inflammation and oxidative stress. Objective The aims of the present study were to investigate whether LDR can prevent type 2 diabetes-induced renal damage and the underlying mechanisms. Methods Mice were fed with a high-fat diet (HFD, 40% of calories from fat) for 12 weeks to induce obesity followed by a single intraperitoneal injection of streptozotocin (STZ, 50 mg/kg) to develop a type 2 diabetic mouse model. The mice were exposed to LDR at different doses (25, 50 and 75 mGy) for 4 or 8 weeks along with HFD treatment. At each time-point, the kidney weight, renal function, blood glucose level and insulin resistance were examined. The pathological changes, renal lipid profiles, inflammation, oxidative stress and fibrosis were also measured. Results HFD/STZ-induced type 2 diabetic mice exhibited severe pathological changes in the kidney and renal dysfunction. Exposure of the mice to LDR for 4 weeks, especially at 50 and 75 mGy, significantly improved lipid profiles, insulin sensitivity and protein kinase B activation, meanwhile, attenuated inflammation and oxidative stress in the diabetic kidney. The LDR-induced anti-oxidative effect was associated with up-regulation of renal nuclear factor E2-related factor-2 (Nrf-2) expression and function. However, the above beneficial effects were weakened once LDR treatment was extended to 8 weeks. Conclusion These results suggest that LDR exposure significantly prevented type 2 diabetes-induced kidney injury characterized by renal dysfunction and pathological changes. The protective mechanisms of LDR are complicated but may be mainly attributed to the attenuation of dyslipidemia and the subsequent lipotoxicity-induced insulin resistance

  18. One-electron reduction of 9, 10-anthraquinone, 1-amino-9, 10-anthraquinone and 1-hydroxy-9, 10-anthraquinone in aqueous-isopropanol-acetone mixed solvent: A pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Pal, H.; Mukherjee, T.; Mittal, J. P.

    1994-12-01

    The semiquinone radicals produced by one-electron reduction of 9, 10-anthraquinone, 1-amino-9, 10-anthraquinone and 1-hydroxy-9, 10-anthraquinone have been characterized in aqueous-organic mixed solvent comprising of 30.2 mol dm -3 water, 5 mol dm -3 isopropanol and 1 mol dm -3 acetone, using the pulse radiolysis technique. Spectroscopic characteristics, the kinetic parameters of formation and decay and one acid dissociation constants of the semiquinones and one-electron reduction potentials of the quinones have been estimated. The characteristics of the present semiquinone systems have been compared with those of other similar systems. The observed differences in characteristics of the semiquinones due to different substitutions have been analysed.

  19. Multiple Pathways for Benzyl Alcohol Oxidation by RuV=O3+ and RuIV=O2+

    SciTech Connect

    Paul, Amit; Hull, Jonathan F.; Norris, Michael R.; Chen, Zuofeng; Ess, Daniel H.; Concepcion, Javier J.; Meyer, Thomas J.

    2011-01-20

    Significant rate enhancements are found for benzyl alcohol oxidation by the RuV=O3+ form of the water oxidation catalyst [Ru(Mebimpy)(bpy)(OH2)]2+ [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy = 2,2'-bipyridine] compared to RuIV=O2+ and for the RuIV=O2+ form with added bases due to a new pathway, concerted hydride proton transfer (HPT).

  20. Multiple Pathways for Benzyl Alcohol Oxidation by RuV=O3+ and RuIV=O2+

    SciTech Connect

    Paul, Amit; Hull, Jonathan F.; Norris, Michael R.; Chen, Zuofeng; Ess, Daniel H.; Concepcion, Javier J.; Meyer, Thomas J.

    2011-01-20

    Significant rate enhancements are found for benzyl alcohol oxidation by the RuV=O3+ form of the water oxidation catalyst [Ru(Mebimpy)(bpy)(OH2)]2+ [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy = 2,2'-bipyridine] compared to RuIV=O2+ and for the RuIV=O2+ form with added bases due to a new pathway involving concerted hydride proton transfer (HPT).

  1. The multiple organ dysfunction syndrome caused by endotoxin in the rat: attenuation of liver dysfunction by inhibitors of nitric oxide synthase.

    PubMed Central

    Thiemermann, C.; Ruetten, H.; Wu, C. C.; Vane, J. R.

    1995-01-01

    1. We have investigated whether (i) endotoxaemia caused by E. coli lipopolysaccharide in the anaesthetized rat causes a multiple organ dysfunction syndrome (MODS; e.g. circulatory failure, renal failure, liver failure), and (ii) an enhanced formation of nitric oxide (NO) due to induction of inducible NO synthase (iNOS) contributes to the MODS. In addition, this study elucidates the beneficial and adverse effects of aminoethyl-isothiourea (AE-ITU), a relatively selective inhibitor of iNOS activity, and NG-methyl-L-arginine (L-NMMA), a non-selective inhibitor of NOS activity on the MODS caused by endotoxaemia. 2. In the anaesthetized rat, LPS caused a fall in mean arterial blood pressure (MAP) from 117 +/- 3 mmHg (time 0) to 97 +/- 4 mmHg at 2 h (P < 0.05, n = 15) and 84 +/- 4 mmHg at 6 h (P < 0.05, n = 15). The pressor effect of noradrenaline (NA, 1 micrograms kg-1, i.v.) was also significantly reduced at 1 to 6 h after LPS (vascular hyporeactivity). Treatment of LPS-rats with AE-ITU (1 mg kg-1, i.v. plus 1 mg kg-1 h-1 starting at 2 h after LPS) caused only a transient rise in MAP, but significantly attenuated the delayed vascular hyporeactivity seen in LPS-rats. Infusion of L-NMMA (3 mg kg-1, i.v. plus 3 mg kg-1 h-1) caused a rapid and sustained rise in MAP and attenuated the delayed vascular hyporeactivity to NA. Neither AE-ITU nor L-NMMA had any effect on either MAP or the pressor effect elicited by NA in rats infused with saline rather than LPS. 3. Endotoxaemia for 6 h was associated with a significant rise in the serum levels of aspartate or alanine aminotransferase (i.e. GOT or GPT), gamma-glutamyl-transferase (gamma GT), and bilirubin, and hence, liver dysfunction. Treatment of LPS-rats with AE-ITU significantly attenuated this liver dysfunction (rise in GOT, GPT, gamma GT and bilirubin) (P < 0.05, n = 10). In contrast, L-NMMA reduced the increase in the serum levels of gamma GT and bilirubin, but not in GOT and GPT (n = 5). Injection of LPS also caused a

  2. Attenuation of endotoxin-induced multiple organ dysfunction by 1-amino-2-hydroxy-guanidine, a potent inhibitor of inducible nitric oxide synthase.

    PubMed Central

    Ruetten, H.; Southan, G. J.; Abate, A.; Thiemermann, C.

    1996-01-01

    1. We have investigated the effects of (i) several guanidines on the activity of the inducible isoform of nitric oxide (NO) synthase (iNOS) in murine cultured macrophages and rat aortic vascular smooth muscle cells (RASM); and (ii) 1-amino-2-hydroxy-guanidine, the most potent inhibitor of iNOS activity discovered, on haemodynamics, multiple organ (liver, renal, and pancreas) dysfunction and iNOS activity in rats with endotoxic shock. 2. The synthesized guanidine analogues caused concentration-dependent inhibitions of the increase in nitrite formation caused by lipopolysaccaride (LPS, 1 microgram ml-1) in J774.2 macrophages and RASM cells with the following rank order of potency: 1-amino-2-hydroxy-guanidine > 1-amino-2-methyl-guanidine > 1-amino-1-methyl-guanidine > 1-amino-1,2-dimethyl-guanidine. Interestingly, 1-amino-2-hydroxy-guanidine (IC50: J774.2, 68 microM; RASM, 114 microM) was more potent in inhibiting nitrite formation caused by LPS than NG-methyl-L-arginine, but less potent than aminoethyl-isothiourea. 3. In the anaesthetized rat, LPS caused a fall in mean arterial blood pressure (MAP) from 115 +/- 4 mmHg (time 0) to 98 +/- 5 mmHg at 2 h (P < 0.05, n = 10) and 69 +/- 5 mmHg at 6 h (P < 0.05, n = 10). The pressor effect of noradrenaline (NA, 1 mg kg-1, i.v.) was also significantly reduced at 1 to 6 h after LPS (vascular hyporeactivity). Treatment of LPS-rats with 1-amino-2-hydroxy-guanidine (10 mg kg-1, i.v. plus 10 mg kg-1 h-1 starting at 2 h after LPS) prevented the delayed hypotension and vascular hyporeactivity seen in LPS-rats. However, 1-amino-2-hydroxy-guanidine had no effect on either MAP or the pressor effect elicited by NA in rats infused with saline rather than LPS. 4. Endotoxaemia for 6 h caused a significant rise in the serum levels of aspartate or alanine aminotransferase (i.e. GOT or GPT) and bilirubin, and hence, liver dysfunction. Treatment of LPS-rats with 1-amino-2-hydroxy-guanidine significantly attenuated the liver dysfunction caused

  3. Hydrogen peroxide contributes to the ultraviolet-B (280-315 nm) induced oxidative stress of plant leaves through multiple pathways.

    PubMed

    Czégény, Gyula; Wu, Min; Dér, András; Eriksson, Leif A; Strid, Åke; Hideg, Éva

    2014-06-27

    Solar UV-B (280-315 nm) radiation is a developmental signal in plants but may also cause oxidative stress when combined with other environmental factors. Using computer modeling and in solution experiments we show that UV-B is capable of photosensitizing hydroxyl radical production from hydrogen peroxide. We present evidence that the oxidative effect of UV-B in leaves is at least twofold: (i) it increases cellular hydrogen peroxide concentrations, to a larger extent in pyridoxine antioxidant mutant pdx1.3-1 Arabidopsis and; (ii) is capable of a partial photo-conversion of both 'natural' and 'extra' hydrogen peroxide to hydroxyl radicals. As stress conditions other than UV can increase cellular hydrogen peroxide levels, synergistic deleterious effects of various stresses may be expected already under ambient solar UV-B. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  4. The chemistry of rhenium and tungsten porphyrin complexes in low oxidation states. Synthesis and characterization of rhenium and tungsten porphyrin dimers containing metal-metal multiple bonds

    SciTech Connect

    Collmann, J.P.; Garner, J.M.; Woo, L.K. )

    1989-10-11

    The coordination chemistry of rhenium and tungsten porphyrin complexes in low oxidation states is presented. W{sup IV}(Por)(Cl){sub 2}, W{sup II}(Por)(H{sub 5}C{sub 6}C{identical to}CC{sub 6}H{sub 5}) and W{sup II}(OEP)(PEt{sub 3}){sub 2} complexes (Por = 5,10,15,20-tetra(4-tolyl)porphyrin (TTP) or 2,3,7,8,12,13,17,18-octaethylporphyrin (OEP) dianions) were found to be similar to the analogous molybdenum porphyrin complexes by spectroscopic and magnetic measurements. UV-visible and vibrational spectroscopies indicate that these oxidations occur at the metal-metal bond rather than the porphyrin ligand.

  5. Multiple organ dysfunction syndrome.

    PubMed

    Parke, A L; Liu, P T; Parke, D V

    2003-01-01

    Multiple organ dysfunction syndrome, including acute respiratory distress syndrome (ARDS) and renal failure, is described, its clinical features outlined, its origins in tissue oxidative stress following severe infections, surgical trauma, ionizing radiation, high-dosage drugs and chemicals, severe hemorrhage, etc., are defined, and its prevention and treatment prescribed.

  6. An experimental comparison of the Marcus-Hush and Butler-Volmer descriptions of electrode kinetics applied to cyclic voltammetry. The one electron reductions of europium (III) and 2-methyl-2-nitropropane studied at a mercury microhemisphere electrode

    NASA Astrophysics Data System (ADS)

    Henstridge, Martin C.; Wang, Yijun; Limon-Petersen, Juan G.; Laborda, Eduardo; Compton, Richard G.

    2011-11-01

    We present a comparative experimental evaluation of the Butler-Volmer and Marcus-Hush models using cyclic voltammetry at a microelectrode. Numerical simulations are used to fit experimental voltammetry of the one electron reductions of europium (III) and 2-methyl-2-nitropropane, in water and acetonitrile, respectively, at a mercury microhemisphere electrode. For Eu (III) very accurate fits to experiment were obtained over a wide range of scan rates using Butler-Volmer kinetics, whereas the Marcus-Hush model was less accurate. The reduction of 2-methyl-2-nitropropane was well simulated by both models, however Marcus-Hush required a reorganisation energy lower than expected.

  7. Aqueous extract of some indigenous medicinal plants inhibits glycation at multiple stages and protects erythrocytes from oxidative damage-an in vitro study.

    PubMed

    Tupe, Rashmi S; Sankhe, Neena M; Shaikh, Shamim A; Phatak, Devyani V; Parikh, Juhi U; Khaire, Amrita A; Kemse, Nisha G

    2015-04-01

    Azadirachta indica, Emblica officinalis, Syzygium cumini and Terminalia bellirica are common in Indian system of traditional medicine for the prevention of diabetes and its complications. The aim of the present study was to comprehensively and comparatively investigate the antiglycation potential of these plant extracts at multiple stages and their possible protective effect against glycated albumin mediated toxicity to erythrocytes. Antiglycation activities of these plant extracts was measured by co-incubation of plant extract with bovine serum albumin-fructose glycation model. The multistage glycation markers- fructosamines (early stage), protein carbonyls (intermediate stage) and AGEs (late stage) are investigated along with measurement of thiols and β aggregation of albumin using amyloid-specific dyes-Congo red and Th T. Protection of erythrocytes from glycated albumin induced toxicity by these plant extracts was assessed by measuring erythrocytes hemolysis, lipid peroxidation, reduced glutathione and intracellular antioxidant capacity. Total phenolics, reducing power and antioxidant activities of the plant extracts were also measured. In vitro glycation assays showed that plant extracts exerted site specific inhibitory effects at multiple stages, with T. bellirica showing maximum attenuation. In erythrocytes, along with the retardation of glycated albumin induced hemolysis and lipid-peroxidation, T. bellirica considerably maintained cellular antioxidant potential. Significant positive correlations were observed between erythrocyte protection parameters with total phenolics. These plant extracts especially T. bellirica prevents glycation induced albumin modifications and subsequent toxicity to erythrocytes which might offer additional protection against diabetic vascular complications.

  8. The multiple acyl-coenzyme A dehydrogenation disorders, glutaric aciduria type II and ethylmalonic-adipic aciduria. Mitochondrial fatty acid oxidation, acyl-coenzyme A dehydrogenase, and electron transfer flavoprotein activities in fibroblasts.

    PubMed Central

    Amendt, B A; Rhead, W J

    1986-01-01

    The multiple acyl-coenzyme A (CoA) dehydrogenation disorders (MAD) include severe (S) and mild (M) variants, glutaric aciduria type II (MAD:S) and ethylmalonic-adipic aciduria (MAD:M). Intact MAD:M mitochondria oxidized [1-14C]octanoate, [1-14C]palmityl-CoA, and [1,5-14C]glutarate at 20-46% of control levels; MAD:S mitochondria oxidized these three substrates at 0.4-18% of control levels. In MAD:M mitochondria, acyl-CoA dehydrogenase (ADH) activities were similar to control, whereas MAD:S ADH activities ranged from 38% to 73% of control. Electron transfer flavoprotein (ETF) activities in five MAD:M cell lines ranged from 29 to 51% of control (P less than 0.01); ETF deficiency was the primary enzymatic defect in two MAD:M lines. In four MAD:S patients, ETF activities ranged from 3% to 6% of control (P less than 0.001); flavin adenine dinucleotide addition increased residual ETF activity from 4% to 21% of control in a single MAD:S line (P less than 0.01). Three MAD:S patients had ETF activities ranging from 33 to 53% of control; other investigators found deficient ETF-dehydrogenase activity in these MAD:S and three of our MAD:M cell lines. PMID:3722376

  9. Hydrogen peroxide and nitric oxide mediated cold- and dehydration-induced myo-inositol phosphate synthase that confers multiple resistances to abiotic stresses.

    PubMed

    Tan, Jiali; Wang, Congying; Xiang, Bin; Han, Ruihong; Guo, Zhenfei

    2013-02-01

    myo-Inositol phosphate synthase (MIPS) is the key enzyme of myo-inositol synthesis, which is a central molecule required for cell metabolism and plant growth as a precursor to a large variety of compounds. A full-length fragment of MfMIPS1 cDNA was cloned from Medicago falcata that is more cold-tolerant than Medicago sativa. While MfMIPS1 transcript was induced in response to cold, dehydration and salt stress, MIPS transcript and myo-inositol were maintained longer and at a higher level in M. falcata than in M. sativa during cold acclimation at 5 °C. MfMIPS1 transcript was induced by hydrogen peroxide (H(2) O(2)) and nitric oxide (NO), but was not responsive to abscisic acid (ABA). Pharmacological experiments revealed that H(2) O(2) and NO are involved in the regulation of MfMIPS1 expression by cold and dehydration, but not by salt. Overexpression of MfMIPS1 in tobacco increased the MIPS activity and levels of myo-inositol, galactinol and raffinose, resulting in enhanced resistance to chilling, drought and salt stresses in transgenic tobacco plants. It is suggested that MfMIPS1 is induced by diverse environmental factors and confers resistance to various abiotic stresses.

  10. Applied light-side coupling with optimized spiral-patterned zinc oxide nanorod coatings for multiple optical channel alcohol vapor sensing

    NASA Astrophysics Data System (ADS)

    Bin Abdul Rahim, Hazli Rafis; Bin Lokman, Muhammad Quisar; Harun, Sulaiman Wadi; Hornyak, Gabor Louis; Sterckx, Karel; Mohammed, Waleed Soliman; Dutta, Joydeep

    2016-07-01

    The width of spiral-patterned zinc oxide (ZnO) nanorod coatings on plastic optical fiber (POF) was optimized theoretically for light-side coupling and found to be 5 mm. Structured ZnO nanorods were grown on large core POFs for the purpose of alcohol vapor sensing. The aim of the spiral patterns was to enhance signal transmission by reduction of the effective ZnO growth area, thereby minimizing light leakage due to backscattering. The sensing mechanism utilized changes in the output signal due to adsorption of methanol, ethanol, and isopropanol vapors. Three spectral bands consisting of red (620 to 750 nm), green (495 to 570 nm), and blue (450 to 495 nm) were applied in measurements. The range of relative intensity modulation (RIM) was determined to be for concentrations between 25 to 300 ppm. Methanol presented the strongest response compared to ethanol and isopropanol in all three spectral channels. With regard to alcohol detection RIM by spectral band, the green channel demonstrated the highest RIM values followed by the blue and red channels, respectively.

  11. Carbonylation and loss-of-function analyses of SBPase reveal its metabolic interface role in oxidative stress, carbon assimilation, and multiple aspects of growth and development in Arabidopsis.

    PubMed

    Liu, Xun-Liang; Yu, Hai-Dong; Guan, Yuan; Li, Ji-Kai; Guo, Fang-Qing

    2012-09-01

    Sedoheptulose-1,7-bisphosphatase (SBPase) is a Calvin cycle enzyme and functions in photosynthetic carbon fixation. We found that SBPase was rapidly carbonylated in response to methyl viologen (MV) treatments in detached leaves of Arabidopsis plants. In vitro activity analysis of the purified recombinant SBPase showed that SBPase was carbonylated by hydroxyl radicals, which led to enzyme inactivation in an H(2)O(2) dose-dependent manner. To determine the conformity with carbonylation-caused loss in enzymatic activity in response to stresses, we isolated a loss-of-function mutant sbp, which is deficient in SBPase-dependent carbon assimilation and starch biosynthesis. sbp mutant exhibited a severe growth retardation phenotype, especially for the developmental defects in leaves and flowers where SBPASE is highly expressed. The mutation of SBPASE caused growth retardation mainly through inhibition of cell division and expansion, which can be partially rescued by exogenous application of sucrose. Our findings demonstrate that ROS-induced oxidative damage to SBPase affects growth, development, and chloroplast biogenesis in Arabidopsis through inhibiting carbon assimilation efficiency. The data presented here provide a case study that such inactivation of SBPase caused by carbonyl modification may be a kind of adaptation for plants to restrict the operation of the reductive pentose phosphate pathway under stress conditions.

  12. The effect of polyol on multiple ligand capped silver alloyed nanobimetallic particles in tri-n-octylphosphine oxide and oleic acid matrices

    NASA Astrophysics Data System (ADS)

    Adeyemi Adekoya, Joseph; Olugbenga Dare, Enock; Olurotimi Ogunniran, Kehinde; Oluwasegun Siyanbola, Tolutope; Oyewale Ajani, Olayinka; Osereme Ehi-Eromosele, Cyril; Revaprasadu, Neerish

    2016-12-01

    The syntheses of Ag/M (M is Co, Ni, Pd, Pt and Ru) alloyed nanobimetallic particles in tri-n-octylphosphine oxide and oleic acid matrices were successfully carried out by the successive reduction of ligand capped metal ions with polyols, which resulted in rapid precipitation of some fractal high index faceted hybrid Ag/M bimetal nanoparticles. The optical measurements revealed the existence of modified surface plasmon band and peak broadening resulting from reaction-limited growth processes of the metal sols, making it possible to monitor the changes spectrometrically. The bimetallic nanoparticles were further characterized by powder x-ray diffraction, x-ray photoelectron spectroscopy and electron microscopy techniques which confirmed the formation of novel core-shell and alloyed clusters. The Ag/M nanoparticles thus synthesized within TOPO/OA matrices indicated significant reduction potential as a result of their energy band gap 2.65-2.77 eV which points to the fact that they could serve as reducing agents for electrocatalytic reaction.

  13. Enhancing optical power of GaN-based light-emitting diodes by nanopatterning on indium tin oxide with tunable fill factor using multiple-exposure nanosphere-lens lithography

    SciTech Connect

    Zhang, Yonghui; Wei, Tongbo Xiong, Zhuo; Chen, Yu; Zhen, Aigong; Shan, Liang; Zhao, Yun; Hu, Qiang; Li, Jinmin; Wang, Junxi

    2014-11-21

    In this study, the multiple-exposure nanosphere-lens lithography method utilizing the polystyrene nanospheres with focusing behavior is investigated and introduced to fabricate diverse photonic crystals (PCs) on indium tin oxide to enhance the optical output power of GaN-based light-emitting diode (LED). Simulated results indicate that the focused light intensity decreases with increasing tilted angle due to the shadow effect introduced by adjacent nanospheres. The fill factor of nanopattern is tunable by controlling tilted angles and exposure times. To attain quadruple PC without overlapping patterns, mathematical calculation model is used to define the optimum range of tilted angles. Angular emission patterns and three-dimensional finite-difference time domain simulated results indicate that the enhanced light extraction of PC LEDs results mainly from diffused scattering effects, and the diffraction effects of PC on light extracted efficiency increase with the increase of fill factor. Furthermore, it is confirmed that the multiple PC can extract more light from GaN into air than common PC with same period and fill factor.

  14. Evolution of Diterpene Metabolism: Sitka Spruce CYP720B4 Catalyzes Multiple Oxidations in Resin Acid Biosynthesis of Conifer Defense against Insects1[C][W][OA

    PubMed Central

    Hamberger, Björn; Ohnishi, Toshiyuki; Hamberger, Britta; Séguin, Armand; Bohlmann, Jörg

    2011-01-01

    Diterpene resin acids (DRAs) are specialized (secondary) metabolites of the oleoresin defense of conifers produced by diterpene synthases and cytochrome P450s of the CYP720B family. The evolution of DRA metabolism shares common origins with the biosynthesis of ent-kaurenoic acid, which is highly conserved in general (primary) metabolism of gibberellin biosynthesis. Transcriptome mining in species of spruce (Picea) and pine (Pinus) revealed CYP720Bs of four distinct clades. We cloned a comprehensive set of 12 different Sitka spruce (Picea sitchensis) CYP720Bs as full-length cDNAs. Spatial expression profiles, methyl jasmonate induction, and transcript enrichment in terpenoid-producing resin ducts suggested a role of CYP720B4 in DRA biosynthesis. CYP720B4 was characterized as a multisubstrate, multifunctional enzyme by the formation of oxygenated diterpenoids in metabolically engineered yeast, yeast in vivo transformation of diterpene substrates, in vitro assays with CYP720B4 protein produced in Escherichia coli, and alteration of DRA profiles in RNA interference-suppressed spruce seedlings. CYP720B4 was active with 24 different diterpenoid substrates, catalyzing consecutive C-18 oxidations in the biosynthesis of an array of diterpene alcohols, aldehydes, and acids. CYP720B4 was most active in the formation of dehydroabietic acid, a compound associated with insect resistance of Sitka spruce. We identified patterns of convergent evolution of CYP720B4 in DRA metabolism and ent-kaurene oxidase CYP701 in gibberellin metabolism and revealed differences in the evolution of specialized and general diterpene metabolism in a gymnosperm. The genomic and functional characterization of the gymnosperm CYP720B family highlights that the evolution of specialized metabolism involves substantial diversification relative to conserved, general metabolism. PMID:21994349

  15. PDE5 inhibitors enhance the lethality of pemetrexed through inhibition of multiple chaperone proteins and via the actions of cyclic GMP and nitric oxide

    PubMed Central

    Booth, Laurence; Roberts, Jane L.; Poklepovic, Andrew; Gordon, Sarah; Dent, Paul

    2017-01-01

    Phosphodiesterase 5 (PDE5) inhibitors prevent the breakdown of cGMP that results in prolonged protein kinase G activation and the generation of nitric oxide. PDE5 inhibitors enhanced the anti-NSCLC cell effects of the NSCLC therapeutic pemetrexed. [Pemetrexed + sildenafil] activated an eIF2α – ATF4 – CHOP – Beclin1 pathway causing formation of toxic autophagosomes; activated a protective IRE1 – XBP-1 – chaperone induction pathway; and activated a toxic eIF2α – CHOP – DR4 / DR5 / CD95 induction pathway. [Pemetrexed + sildenafil] reduced the expression of c-FLIP-s, MCL-1 and BCL-XL that was blocked in a cell-type -dependent fashion by either over-expression of HSP90 / GRP78 / HSP70 / HSP27 or by blockade of eIF2α-CHOP signaling. Knock down of PKGI/II abolished the ability of sildenafil to enhance pemetrexed toxicity whereas pan-inhibition of NOS using L-NAME or knock down of [iNOS + eNOS] only partially reduced the lethal drug interaction. Pemetrexed reduced the ATPase activities of HSP90 and HSP70 in an ATM-AMPK-dependent fashion that was enhanced by sildenafil signaling via PKGI/II. The drug combination activated an ATM-AMPK-TSC2 pathway that was associated with reduced mTOR S2448 and ULK-1 S757 phosphorylation and increased ULK-1 S317 and ATG13 S318 phosphorylation. These effects were prevented by chaperone over-expression or by expression of an activated form of mTOR that prevented autophagosome formation and reduced cell killing. In two models of NSCLC, sildenafil enhanced the ability of pemetrexed to suppress tumor growth. Collectively we argue that the combination of [pemetrexed + PDE5 inhibitor] should be explored in a new NSCLC phase I trial. PMID:27903966

  16. Q-switched erbium doped fiber laser based on single and multiple walled carbon nanotubes embedded in polyethylene oxide film as saturable absorber

    NASA Astrophysics Data System (ADS)

    Ahmed, M. H. M.; Ali, N. M.; Salleh, Z. S.; Rahman, A. A.; Harun, S. W.; Manaf, M.; Arof, H.

    2015-01-01

    A passive, stable and low cost Q-switched Erbium-doped fiber laser (EDFL) is demonstrated using both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs), which are embedded in polyethylene oxide (PEO) film as a saturable absorber (SA). The film is sandwiched between two FC/PC fiber connectors and integrated into the laser cavity for Q-switching pulse generation operating at wavelength of 1533.6 nm. With SWCNTs, the laser produces a stable pulse train with repetition rate and pulse width ranging from 9.52 to 33.33 kHz and 16.8 to 8.0 μs while varying the 980 nm pump power from 48.5 mW to 100.4 mW. On the other hand, with MWCNTs, the repetition rate and pulse width can be tuned in a wider range of 6.12-33.62 kHz and 9.5- 4.2 μs, respectively as the pump power increases from 37.9 to 120.6 mW. The MWCNTs produce the pulse train at a lower threshold and attain a higher repetition rate compared to the SWCNTs. This is due to thicker carbon nanotubes layer of the MWCNTs which provides more absorption and consequently higher damage threshold. The Q-switched EDFL produces the highest pulse energy of 531 nJ at pump power of 37.9 mW with the use of MWCNTs-PEO SA.

  17. Green way genesis of silver nanoparticles using multiple fruit peels waste and its antimicrobial, anti-oxidant and anti-tumor cell line studies

    NASA Astrophysics Data System (ADS)

    Naganathan, Kiruthika; Thirunavukkarasu, Somanathan

    2017-04-01

    Green synthesis of silver nanoparticles (SNP) opens a new path to kill and prevent various infectious diseases and also tumor. In this study, we have synthesized silver nanoparticles using multiple fruit peel waste (pomegranate, orange, banana and apple (POBA)). The primarily nanoparticles formation has been confirmed by the color change. The synthesized SNP were analyzed by various physicochemical techniques such as UV- Visible spectroscopy, x-ray diffraction (XRD), fourier transform infra red (FT-IR) spectroscopy and transmission electron microscope (TEM). The formation of SNP was confirmed by its absorbance peak observed at 430 nm in UV-Visible spectrum. Further, the obtained SNP were identified by XRD and TEM, respectively to know the crystalline nature and size and shape of the particles. The activities of SNP were checked with human pathogens (Salmonella, E.coli and Pseudomonas), plant pathogen (Fusarium) and marine pathogen (Aeromonas hydrophila) and also studied the scavenging effect and anticancer properties against MCF-7 cell lines. This studies proves that the SNP prepared from fruit waste peel extract approach appears extremely fast, cost efficient, eco-friendly and alternative for conventional methods of SNP synthesis to promote the usage of these nanoparticles in medicinal application.

  18. Multiple myeloma

    MedlinePlus

    Plasma cell dyscrasia; Plasma cell myeloma; Malignant plasmacytoma; Plasmacytoma of bone; Myeloma - multiple ... Multiple myeloma most commonly causes: Low red blood cell count ( anemia ), which can lead to fatigue and ...

  19. Multiple Sclerosis

    MedlinePlus

    Multiple sclerosis Overview By Mayo Clinic Staff Multiple sclerosis (MS) is a potentially disabling disease of the brain and spinal cord (central nervous system). In MS, the immune system attacks the protective ...

  20. Multiple Sclerosis

    MedlinePlus

    Multiple sclerosis (MS) is a nervous system disease that affects your brain and spinal cord. It damages the ... attacks healthy cells in your body by mistake. Multiple sclerosis affects women more than men. It often begins ...

  1. Multiple Myeloma

    MedlinePlus

    Multiple myeloma Overview Multiple myeloma is a cancer that forms in a type of white blood cell called a plasma cell. Plasma cells help ... by making antibodies that recognize and attack germs. Multiple myeloma causes cancer cells to accumulate in the bone ...

  2. Induction of oxidative damage in the testes and spermatozoa and hematotoxicity in rats exposed to multiple doses of ethylene glycol monoethyl ether.

    PubMed

    Adedara, Isaac A; Farombi, Ebenezer O

    2010-10-01

    -exposed rats than in the controls. EGEE at 100 mg/kg bw produced minor effect on haematological parameters but adversely affected testes and spermatozoa. In summary, short term administration of EGEE is hematotoxic and gonadotoxic and its effects on male reproduction could be due to the induction of oxidative stress in testes and spermatozoa.

  3. Multiplicity Counting

    SciTech Connect

    Geist, William H.

    2015-12-01

    This set of slides begins by giving background and a review of neutron counting; three attributes of a verification item are discussed: 240Pueff mass; α, the ratio of (α,n) neutrons to spontaneous fission neutrons; and leakage multiplication. It then takes up neutron detector systems – theory & concepts (coincidence counting, moderation, die-away time); detector systems – some important details (deadtime, corrections); introduction to multiplicity counting; multiplicity electronics and example distributions; singles, doubles, and triples from measured multiplicity distributions; and the point model: multiplicity mathematics.

  4. Detailed electrochemical studies of the tetraruthenium polyoxometalate water oxidation catalyst in acidic media: identification of an extended oxidation series using Fourier transformed alternating current voltammetry.

    PubMed

    Lee, Chong-Yong; Guo, Si-Xuan; Murphy, Aidan F; McCormac, Timothy; Zhang, Jie; Bond, Alan M; Zhu, Guibo; Hill, Craig L; Geletii, Yurii V

    2012-11-05

    The electrochemistry of the water oxidation catalyst, Rb(8)K(2)[{Ru(4)O(4)(OH)(2)(H(2)O)(4)}(γ-SiW(10)O(36))(2)] (Rb(8)K(2)-1(0)) has been studied in the presence and absence of potassium cations in both hydrochloric and sulfuric acid solutions by transient direct current (dc) cyclic voltammetry, a steady state dc method in the rotating disk configuration and the kinetically sensitive technique of Fourier transformed large-amplitude alternating current (ac) voltammetry. In acidic media, the presence of potassium ions affects the kinetics (apparent rate of electron transfer) and thermodynamics (reversible potentials) of the eight processes (A'/A to H/H') that are readily detected under dc voltammetric conditions. The six most positive processes (A'/A to F/F'), each involve a one electron ruthenium based charge transfer step (A'/A, B'/B are Ru(IV/V) oxidation and C/C' to F/F' are Ru(IV/III) reduction). The apparent rate of electron transfer of the ruthenium centers in sulfuric acid is higher than in hydrochloric acid. The addition of potassium cations increases the apparent rates and gives rise to a small shift of reversible potential. Simulations of the Fourier transformed ac voltammetry method show that the B'/B, E/E', and F/F' processes are quasi-reversible, while the others are close to reversible. A third Ru(IV/V) oxidation process is observed just prior to the positive potential limit via dc methods. Importantly, the ability of the higher harmonic components of the ac method to discriminate against the irreversible background solvent process allows this (process I) as well as an additional fourth reversible ruthenium based process (J) to be readily identified. The steady-state rotating disk electrode (RDE) method confirmed that all four Ru-centers in Rb(8)K(2)-1(0) are in oxidation state IV. The dc and ac data indicate that reversible potentials of the four ruthenium centers are evenly spaced, which may be relevant to understanding of the water oxidation

  5. The nitric oxide producing reactions of hydroxyurea.

    PubMed

    King, S Bruce

    2003-03-01

    Hydroxyurea is used to treat a variety of cancers and sickle cell disease. Despite this widespread use, a complete mechanistic understanding of the beneficial actions of this compound remains to be understood. Hydroxyurea inhibits ribonucleotide reductase and increases the levels of fetal hemoglobin, which explains a portion of the effects of this drug. Administration of hydroxyurea to patients results in a significant increase in levels of iron nitrosyl hemoglobin, nitrite and nitrate suggesting the in vivo metabolism of hydroxyurea to nitric oxide. Formation of nitric oxide from hydroxyurea may explain a portion of the observed effects of hydroxyurea treatment. At the present, the mechanism or mechanisms of nitric oxide release, the identity of the in vivo oxidant and the site of metabolism remain to be identified. Chemical oxidation of hydroxyurea produces nitric oxide and nitroxyl, the one-electron reduced form of nitric oxide. These oxidative pathways generally proceed through the nitroxide radical (2) or C-nitrosoformamide (3). Biological oxidants, including both iron and copper containing enzymes and proteins, also convert hydroxyurea to nitric oxide or its decomposition products in vitro and these reactions also occur through these intermediates. A number of other reactions of hydroxyurea including the reaction with ribonucleotide reductase and irradiation demonstrate the potential to release nitric oxide and should be further investigated. Gaining an understanding of the metabolism of hydroxyurea to nitric oxide will provide valuable information towards the treatment of these disorders and may lead to the development of better therapeutic agents.

  6. Theoretical study of one-electron bonds in a series of high-spin lithium-beryllium-hydrogen clusters: ?Valence shell single-electron repulsion? rule and electron localization function analysis

    NASA Astrophysics Data System (ADS)

    Chaquin, Patrick; Chevreau, Hilaire

    A series of high-spin clusters containing Li, H, and Be in which the valence shell molecular orbitals (MOs) are occupied by a single electron has been characterized using ab initio and density functional theory (DFT) calculations. A first type (5Li2, n+1LiHn+ (n = 2-5), 8Li2H6+) possesses only one electron pair in the lowest MO, with bond energies of ?3 kcal/mol. In a second type, all the MOs are singly occupied, which results in highly excited species that nevertheless constitute a marked minimum on their potential energy surface (PES). Thus, it is possible to design a larger panel of structures (8LiBe, 7Li2, 8Li2-, 4LiH+, 6BeH2+, n+3LiHn+ (n = 3, 4), n+2LiHn2+ (n = 4-6), 8Li2H2+, 9Li2H42+, 22Li3Be3 and 22Li6H63+), single-electron equivalent to doublet ?classical? molecules ranging from CO to C6H6. The geometrical structure is studied in relation to the valence shell single-electron repulsion (VSEPR) theory and the electron localization function (ELF) is analyzed, revealing a striking similarity with the corresponding structure having paired electrons.

  7. Multiple myeloma.

    PubMed

    Peller, Patrick J

    2015-04-01

    This article presents a review of multiple myeloma, precursor states, and related plasma cell disorders. The clinical roles of fluorodeoxyglucose PET/computed tomography (CT) and the potential to improve the management of patients with multiple myeloma are discussed. The clinical and research data supporting the utility of PET/CT use in evaluating myeloma and other plasma cell dyscrasias continues to grow.

  8. Application of least squares support vector regression and linear multiple regression for modeling removal of methyl orange onto tin oxide nanoparticles loaded on activated carbon and activated carbon prepared from Pistacia atlantica wood.

    PubMed

    Ghaedi, M; Rahimi, Mahmoud Reza; Ghaedi, A M; Tyagi, Inderjeet; Agarwal, Shilpi; Gupta, Vinod Kumar

    2016-01-01

    Two novel and eco friendly adsorbents namely tin oxide nanoparticles loaded on activated carbon (SnO2-NP-AC) and activated carbon prepared from wood tree Pistacia atlantica (AC-PAW) were used for the rapid removal and fast adsorption of methyl orange (MO) from the aqueous phase. The dependency of MO removal with various adsorption influential parameters was well modeled and optimized using multiple linear regressions (MLR) and least squares support vector regression (LSSVR). The optimal parameters for the LSSVR model were found based on γ value of 0.76 and σ(2) of 0.15. For testing the data set, the mean square error (MSE) values of 0.0010 and the coefficient of determination (R(2)) values of 0.976 were obtained for LSSVR model, and the MSE value of 0.0037 and the R(2) value of 0.897 were obtained for the MLR model. The adsorption equilibrium and kinetic data was found to be well fitted and in good agreement with Langmuir isotherm model and second-order equation and intra-particle diffusion models respectively. The small amount of the proposed SnO2-NP-AC and AC-PAW (0.015 g and 0.08 g) is applicable for successful rapid removal of methyl orange (>95%). The maximum adsorption capacity for SnO2-NP-AC and AC-PAW was 250 mg g(-1) and 125 mg g(-1) respectively.

  9. Ligand-centred oxidative chemistry in sterically hindered salen complexes: an interesting case with nickel.

    PubMed

    Thomas, F

    2016-07-05

    Salen ligands are ubiquitous ligands because they can be readily prepared by condensation of a diamine with two equivalents of salicylaldehyde. They form stable complexes with a great variety of metal ions and find applications in various fields, especially catalysis. The introduction of chirality at the bridge and the adjunction of sterically demanding tert-butyl groups in ortho and para positions of the phenols allow for efficient enantioselective catalysis. On the other hand, early investigations on the oxidation chemistry of phenols highlighted that the incorporation of tert-butyl groups in ortho and para positions can stabilize enormously the one-electron oxidized product e.g. the phenoxyl radical. The redox-activity of sterically hindered salen ligands will be discussed in this perspective article. We will focus our attention on nickel salen complexes since both the metal and the ligand are potentially redox-active, while the oxidized products are stable enough to be characterized by EPR and NIR spectroscopies. Additionally, the one-electron oxidized species could be isolated as single crystals in some instances, giving detailed pictures of their electronic structure. Both the Ni(ii)-radical and Ni(iii) bis(phenolate) valence tautomers are accessible upon one-electron oxidation. The substituents, metal coordination sphere, solvent and temperature are crucial factors that dictate the electronic structure of these one-electron oxidized salen complexes.

  10. Multiple homicides.

    PubMed

    Copeland, A R

    1989-09-01

    A study of multiple homicides or multiple deaths involving a solitary incident of violence by another individual was performed on the case files of the Office of the Medical Examiner of Metropolitan Dade County in Miami, Florida, during 1983-1987. A total of 107 multiple homicides were studied: 88 double, 17 triple, one quadruple, and one quintuple. The 236 victims were analyzed regarding age, race, sex, cause of death, toxicologic data, perpetrator, locale of the incident, and reason for the incident. This article compares this type of slaying with other types of homicide including those perpetrated by serial killers. Suggestions for future research in this field are offered.

  11. Nitric oxide synthases: structure, function and inhibition.

    PubMed Central

    Alderton, W K; Cooper, C E; Knowles, R G

    2001-01-01

    This review concentrates on advances in nitric oxide synthase (NOS) structure, function and inhibition made in the last seven years, during which time substantial advances have been made in our understanding of this enzyme family. There is now information on the enzyme structure at all levels from primary (amino acid sequence) to quaternary (dimerization, association with other proteins) structure. The crystal structures of the oxygenase domains of inducible NOS (iNOS) and vascular endothelial NOS (eNOS) allow us to interpret other information in the context of this important part of the enzyme, with its binding sites for iron protoporphyrin IX (haem), biopterin, L-arginine, and the many inhibitors which interact with them. The exact nature of the NOS reaction, its mechanism and its products continue to be sources of controversy. The role of the biopterin cofactor is now becoming clearer, with emerging data implicating one-electron redox cycling as well as the multiple allosteric effects on enzyme activity. Regulation of the NOSs has been described at all levels from gene transcription to covalent modification and allosteric regulation of the enzyme itself. A wide range of NOS inhibitors have been discussed, interacting with the enzyme in diverse ways in terms of site and mechanism of inhibition, time-dependence and selectivity for individual isoforms, although there are many pitfalls and misunderstandings of these aspects. Highly selective inhibitors of iNOS versus eNOS and neuronal NOS have been identified and some of these have potential in the treatment of a range of inflammatory and other conditions in which iNOS has been implicated. PMID:11463332

  12. Oxidative DNA modifications.

    PubMed

    Poulsen, Henrik E

    2005-07-01

    the separation procedure proper prior to detection. A large effort from 20+ laboratories supported by a grant from the EU has reduced artifacts considerably and work towards interlaboratory standardization of the methodology is in progress. The presently agreed "normal" levels of the most frequent known lesion 8-oxodG is about 5 per million dG's in DNA. A comprehensive evaluation of the evidence, from chemistry to clinical and epidemiological trials, linking oxidative modifications to cancer will be given. Finally, an estimate of the quantitative role oxidative DNA modifications play among the multiplicity of other insults is given. While there is no question that all of these oxidative mechanisms do exist, quantitative data on their importance for the human situation do not exist. Prospective human studies that can provide such quantitative data on different mechanisms are underway.

  13. Parenting Multiples

    MedlinePlus

    ... parents. It's important for caretakers to spend time speaking directly to each child, as well as reading to them and encouraging language. Social skills can come earlier for multiples, simply because they' ...

  14. Multiple myeloma

    PubMed Central

    2010-01-01

    Abstract Advances in the imaging and treatment of multiple myeloma have occurred over the past decade. This article summarises the current status and highlights how an understanding of both is necessary for optimum management. PMID:20159661

  15. Multiple Pregnancy

    MedlinePlus

    ... result in twins, triplets, or more. In vitro fertilization can lead to a multiple pregnancy if more ... egg that are usually genetically identical. In Vitro Fertilization: A procedure in which an egg is removed ...

  16. Multiple emulsions.

    PubMed

    Yazan, Y; Seiller, M; Puisieux, F

    1993-06-01

    The purpose of this review is to update the information on multiple emulsions known to be promising delivery systems for both pharmaceuticals and cosmetic materials. The possibility of encapsulating active substances within liquid membranes may lead to interesting opportunities in both fields. Thus the formulation, manufacturing, stabilization, analysis and potential application of multiple emulsions seems to be worth surveying, putting a special emphasis on cosmetic applications.

  17. JS-K, a GST-activated nitric oxide generator, induces DNA double-strand breaks, activates DNA damage response pathways, and induces apoptosis in vitro and in vivo in human multiple myeloma cells.

    PubMed

    Kiziltepe, Tanyel; Hideshima, Teru; Ishitsuka, Kenji; Ocio, Enrique M; Raje, Noopur; Catley, Laurence; Li, Chun-Qi; Trudel, Laura J; Yasui, Hiroshi; Vallet, Sonia; Kutok, Jeffery L; Chauhan, Dharminder; Mitsiades, Constantine S; Saavedra, Joseph E; Wogan, Gerald N; Keefer, Larry K; Shami, Paul J; Anderson, Kenneth C

    2007-07-15

    Here we investigated the cytotoxicity of JS-K, a prodrug designed to release nitric oxide (NO(*)) following reaction with glutathione S-transferases, in multiple myeloma (MM). JS-K showed significant cytotoxicity in both conventional therapy-sensitive and -resistant MM cell lines, as well as patient-derived MM cells. JS-K induced apoptosis in MM cells, which was associated with PARP, caspase-8, and caspase-9 cleavage; increased Fas/CD95 expression; Mcl-1 cleavage; and Bcl-2 phosphorylation, as well as cytochrome c, apoptosis-inducing factor (AIF), and endonuclease G (EndoG) release. Moreover, JS-K overcame the survival advantages conferred by interleukin-6 (IL-6) and insulin-like growth factor 1 (IGF-1), or by adherence of MM cells to bone marrow stromal cells. Mechanistic studies revealed that JS-K-induced cytotoxicity was mediated via NO(*) in MM cells. Furthermore, JS-K induced DNA double-strand breaks (DSBs) and activated DNA damage responses, as evidenced by neutral comet assay, as well as H2AX, Chk2 and p53 phosphorylation. JS-K also activated c-Jun NH(2)-terminal kinase (JNK) in MM cells; conversely, inhibition of JNK markedly decreased JS-K-induced cytotoxicity. Importantly, bortezomib significantly enhanced JS-K-induced cytotoxicity. Finally, JS-K is well tolerated, inhibits tumor growth, and prolongs survival in a human MM xenograft mouse model. Taken together, these data provide the preclinical rationale for the clinical evaluation of JS-K to improve patient outcome in MM.

  18. Multiple myeloma.

    PubMed

    Kumar, Shaji K; Rajkumar, Vincent; Kyle, Robert A; van Duin, Mark; Sonneveld, Pieter; Mateos, María-Victoria; Gay, Francesca; Anderson, Kenneth C

    2017-07-20

    Multiple myeloma is a malignancy of terminally differentiated plasma cells, and patients typically present with bone marrow infiltration of clonal plasma cells and monoclonal protein in the serum and/or urine. The diagnosis of multiple myeloma is made when clear end-organ damage attributable to the plasma cell proliferative disorder or when findings that suggest a high likelihood of their development are present. Distinguishing symptomatic multiple myeloma that requires treatment from the precursor stages of monoclonal gammopathy of undetermined significance and smouldering multiple myeloma is important, as observation is the standard for those conditions. Much progress has been made over the past decade in the understanding of disease biology and individualized treatment approaches. Several new classes of drugs, such as proteasome inhibitors and immunomodulatory drugs, have joined the traditional armamentarium (corticosteroids, alkylating agents and anthracyclines) and, along with high-dose therapy and autologous haemopoietic stem cell transplantation, have led to deeper and durable clinical responses. Indeed, an increasing proportion of patients are achieving lasting remissions, raising the possibility of cure for this disease. Success will probably depend on using combinations of effective agents and treating patients in the early stages of disease, such as patients with smouldering multiple myeloma.

  19. [Multiple meningiomas].

    PubMed

    Terrier, L-M; François, P

    2016-06-01

    Multiple meningiomas (MMs) or meningiomatosis are defined by the presence of at least 2 lesions that appear simultaneously or not, at different intracranial locations, without the association of neurofibromatosis. They present 1-9 % of meningiomas with a female predominance. The occurrence of multiple meningiomas is not clear. There are 2 main hypotheses for their development, one that supports the independent evolution of these tumors and the other, completely opposite, that suggests the propagation of tumor cells of a unique clone transformation, through cerebrospinal fluid. NF2 gene mutation is an important intrinsic risk factor in the etiology of multiple meningiomas and some exogenous risk factors have been suspected but only ionizing radiation exposure has been proven. These tumors can grow anywhere in the skull but they are more frequently observed in supratentorial locations. Their histologic types are similar to unique meningiomas of psammomatous, fibroblastic, meningothelial or transitional type and in most cases are benign tumors. The prognosis of these tumors is eventually good and does not differ from the unique tumors except for the cases of radiation-induced multiple meningiomas, in the context of NF2 or when diagnosed in children where the outcome is less favorable. Each meningioma lesion should be dealt with individually and their multiple character should not justify their resection at all costs.

  20. Multiple Intelligences.

    ERIC Educational Resources Information Center

    Laughlin, Janet

    1999-01-01

    Details the characteristics of Howard Gardner's seven multiple intelligences (MI): linguistic, logical-mathematical, bodily-kinesthetic, spatial, musical, interpersonal, and intrapersonal. Discusses the implications of MI for instruction. Explores how students can study using their preferred learning style - visual, auditory, and physical study…

  1. Multiple Sclerosis.

    ERIC Educational Resources Information Center

    Plummer, Nancy; Michael, Nancy, Ed.

    This module on multiple sclerosis is intended for use in inservice or continuing education programs for persons who administer medications in long-term care facilities. Instructor information, including teaching suggestions, and a listing of recommended audiovisual materials and their sources appear first. The module goal and objectives are then…

  2. Multiple Sclerosis.

    ERIC Educational Resources Information Center

    Plummer, Nancy; Michael, Nancy, Ed.

    This module on multiple sclerosis is intended for use in inservice or continuing education programs for persons who administer medications in long-term care facilities. Instructor information, including teaching suggestions, and a listing of recommended audiovisual materials and their sources appear first. The module goal and objectives are then…

  3. Myelin basic protein-primed T cells of female but not male mice induce nitric-oxide synthase and proinflammatory cytokines in microglia: implications for gender bias in multiple sclerosis.

    PubMed

    Dasgupta, Subhajit; Jana, Malabendu; Liu, Xiaojuan; Pahan, Kalipada

    2005-09-23

    Females are more susceptible than males to multiple sclerosis (MS). However, the underlying mechanism behind this gender difference is poorly understood. Because the presence of neuroantigen-primed T cells within the CNS is necessary for the development of MS, the present study was undertaken to investigate the activation of microglia by myelin basic protein (MBP)-primed T cells of male, female, and castrated male mice. Interestingly, MBP-primed T cells isolated from female and castrated male but not from male mice induced the expression of inducible nitric-oxide synthase (iNOS) and proinflammatory cytokines (interleukin-1beta (IL-1beta), IL-1alpha, IL-6, and tumor necrosis factor-alpha) in microglia by cell-cell contact. Again there was no apparent defect in male microglia, because MBP-primed T cells isolated from female and castrated male but not male mice were capable of inducing the production of NO in male primary microglia. Inhibition of female T cell contact-mediated microglial expression of proinflammatory molecules by dominant-negative mutants of p65 and C/EBPbeta suggest that female MBP-primed T cells induce microglial expression of proinflammatory molecules through the activation of NF-kappaB and C/EBPbeta. Interestingly, MBP-primed T cells of male, female, and castrated male mice were able to induce microglial activation of NF-kappaB. However, MBP-primed T cells of female and castrated male but not male mice induced microglial activation of C/EBPbeta. These studies suggest that microglial activation of C/EBPbeta but not NF-kappaB by T cell:microglial contact is a gender-specific event and that male MBP-primed T cells are not capable of inducing microglial expression of proinflammatory molecules due to their inability to induce the activation of C/EBPbeta in microglia. This novel gender-sensitive activation of microglia by neuroantigen-primed T cell contact could be one of the mechanisms behind the female-loving nature of MS.

  4. Photocatalytic Anion Oxidation and Applications in Organic Synthesis.

    PubMed

    Hering, Thea; Meyer, Andreas Uwe; König, Burkhard

    2016-08-19

    Ions and radicals of the same kind differ by one electron only. The oxidation of many stable inorganic anions yields their corresponding highly reactive radicals, and visible light excitable photocatalysts can provide the required oxidation potential for this transformation. Air oxygen serves as the terminal oxidant, or cheap sacrificial oxidants are used, providing a very practical approach for generating reactive inorganic radicals for organic synthesis. We discuss in this perspective several recently reported examples: Nitrate radicals are obtained by one-electron photooxidation of nitrate anions and are very reactive toward organic molecules. The photooxidation of sulfinate salts yields the much more stable sulfone radicals, which smoothly add to double bonds. A two-electron oxidation of chloride anions to electrophilic chlorine species reacting with arenes in aromatic substitutions extends the method beyond radical reactions. The chloride anion oxidation proceeds via photocatalytically generated peracidic acid as the oxidation reagent. Although the number of reported examples of photocatalytically generated inorganic radical intermediates for organic synthesis is still small, future extension of the concept to other inorganic ions as radical precursors is a clear perspective.

  5. The Oxidation of Cysteine, Cysteinesulfinic Acid and Cysteic Acid on a Polycrystalline Gold Electrode

    DTIC Science & Technology

    1993-04-15

    The mechanism of cysteine, cysteinesulfinic acid and cysteic acid electrooxidation in perchloric acid solutions has been studied using cyclic ... voltammetry . All compounds investigated have been found to be chemisorbed on a polycrystalline gold electrode and oxidized with four, two or one electron

  6. Modulation of Phenol Oxidation in Cofacial Dyads.

    PubMed

    Koo, Bon Jun; Huynh, Michael; Halbach, Robert L; Stubbe, JoAnne; Nocera, Daniel G

    2015-09-23

    The presentation of two phenols on a xanthene backbone is akin to the tyrosine dyad (Y730 and Y731) of ribonucleotide reductase. X-ray crystallography reveals that the two phenol moieties are cofacially disposed at 4.35 Å. Cyclic voltammetry reveals that phenol oxidation is modulated within the dyad, which exhibits a splitting of one-electron waves with the second oxidation of the phenol dyad occurring at larger positive potential than that of a typical phenol. In contrast, a single phenol appended to a xanthene exhibits a two-electron process, consistent with reported oxidation pathways of phenols in acetonitrile. The perturbation of the phenol potential by stacking is reminiscent of a similar effect for guanines stacked within DNA base pairs.

  7. Multiple myeloma

    PubMed Central

    Rajkumar, S. Vincent

    2008-01-01

    Multiple myeloma is a clonal plasma cell malignancy that accounts for slightly more than 10% of all hematologic cancers. In this paper, we present a historically focused review of the disease, from the description of the first case in 1844 to the present. The evolution of drug therapy and stem-cell transplantation for the treatment of myeloma, as well as the development of new agents, is discussed. We also provide an update on current concepts of diagnosis and therapy, with an emphasis on how treatments have emerged from a historical perspective after certain important discoveries and the results of experimental studies. PMID:18332230

  8. Multiple sclerosis.

    PubMed

    Files, Daniel Kane; Jausurawong, Tani; Katrajian, Ruba; Danoff, Robert

    2015-06-01

    Multiple sclerosis (MS) is a chronic, debilitating disease that can have devastating effects. Presentation varies widely in symptoms, pace, and progression. In addition to a thorough history and physical examination, diagnostic tools required to diagnose MS and exclude other diagnoses include MRI, evoked potential testing, and cerebrospinal fluid analysis. Although the disease is not curable presently, quality of life can be improved by minimizing the frequency and severity of disease burden. Disease modification, symptom management, preservation of function, and treatment of psychosocial issues are paramount to enhance the quality of life for the patient affected with MS.

  9. Nitric Oxide Synthases and Atrial Fibrillation

    PubMed Central

    Bonilla, Ingrid M.; Sridhar, Arun; Györke, Sandor; Cardounel, Arturo J.; Carnes, Cynthia A.

    2012-01-01

    Oxidative stress has been implicated in the pathogenesis of atrial fibrillation. There are multiple systems in the myocardium which contribute to redox homeostasis, and loss of homeostasis can result in oxidative stress. Potential sources of oxidants include nitric oxide synthases (NOS), which normally produce nitric oxide in the heart. Two NOS isoforms (1 and 3) are normally expressed in the heart. During pathologies such as heart failure, there is induction of NOS 2 in multiple cell types in the myocardium. In certain conditions, the NOS enzymes may become uncoupled, shifting from production of nitric oxide to superoxide anion, a potent free radical and oxidant. Multiple lines of evidence suggest a role for NOS in the pathogenesis of atrial fibrillation. Therapeutic approaches to reduce atrial fibrillation by modulation of NOS activity may be beneficial, although further investigation of this strategy is needed. PMID:22536189

  10. Multiple Inflation

    NASA Astrophysics Data System (ADS)

    Murphy, Philip Joseph

    1987-09-01

    The Theory of Inflation, namely, that at some point the entropy content of the universe was greatly increased, has much promise. It may solve the puzzles of homogeneity and the creation of structure. However, no particle physics model has yet been found that can successfully drive inflation. The difficulty in satisfying the constraint that the isotropy of the microwave background places on the effective potential of prospective models is immense. In this work we have codified the requirements of such models in a most general form. We have carefully calculated the amounts of inflation the various problems of the Standard Model need for their solution. We have derived a completely model independent upper bound on the inflationary Hubble parameter. We have developed a general notation with which to probe the possibilities of Multiple Inflation. We have shown that only in very unlikely circumstances will any evidence of an earlier inflation, survive the de Sitter period of its successor. In particular, it is demonstrated that it is most unlikely that two bouts of inflation will yield high amplitudes of density perturbations on small scales and low amplitudes on large. We conclude that, while multiple inflation will be of great theoretical interest, it is unlikely to have any observational impact.

  11. [Multiple myeloma].

    PubMed

    Abe, Masahiro; Miki, Hirokazu; Nakamura, Shingen

    2016-03-01

    Owing to the positive clinical benefits obtained with new agents, complete remission (CR) can be used as a surrogate for overall survival, and should be achieved. Although multiple myeloma is a heterogeneous disease in terms of myeloma cell- and patient-related risk factors, patients should receive the most effective combination therapy based on proteasome inhibitors and/or immunomodulatory drugs (IMiDs) as backbone medication irrespective of the risks encountered in the setting of induction therapy ("one-size-fits-all" therapy), followed by consolidation/maintenance therapy to achieve CR with the ultimate goal of extended survival. Myeloma-defining biomarkers have been established to identify high-risk smoldering myeloma requiring treatment. The development of salvage treatments yielding better outcomes for relapsed/refractory myeloma is urgently needed. Upcoming novel molecular targeting agents with different modes of action and immunotherapeutic agents will be integrated into myeloma treatment regimens with a great therapeutic impact, and further evolution of the treatment paradigm for multiple myeloma is eagerly anticipated.

  12. [Multiple apheresis].

    PubMed

    Coffe, C

    2007-05-01

    Multiple apheresis makes it possible to obtain at least two labile blood components from a single donor using a cell separator. It can be either multicomponent apheresis leading to the preparation of at least two different blood component types or red blood cell apheresis providing two identical red blood cell concentrates. These techniques available in addition to whole blood donation, are modifying collection strategies in many Etablissements Français du Sang and will contribute to improve stock logistics in the future. In areas with insufficient stock, these procedures will help achieve blood component self-sufficiency. The author first describes the principle underlying different--current or future--techniques as well as their advantages and drawbacks. He finally addresses the potential impact of these processes on the evolution of blood collection and the advantages to be gained.

  13. Oxidative stress and oxidative damage in chemical carcinogenesis

    SciTech Connect

    Klaunig, James E. Wang Zemin; Pu Xinzhu; Zhou Shaoyu

    2011-07-15

    Reactive oxygen species (ROS) are induced through a variety of endogenous and exogenous sources. Overwhelming of antioxidant and DNA repair mechanisms in the cell by ROS may result in oxidative stress and oxidative damage to the cell. This resulting oxidative stress can damage critical cellular macromolecules and/or modulate gene expression pathways. Cancer induction by chemical and physical agents involves a multi-step process. This process includes multiple molecular and cellular events to transform a normal cell to a malignant neoplastic cell. Oxidative damage resulting from ROS generation can participate in all stages of the cancer process. An association of ROS generation and human cancer induction has been shown. It appears that oxidative stress may both cause as well as modify the cancer process. Recently association between polymorphisms in oxidative DNA repair genes and antioxidant genes (single nucleotide polymorphisms) and human cancer susceptibility has been shown.

  14. Multiple sclerosis

    PubMed Central

    Boster, Aaron L.; Racke, Michael K.

    2013-01-01

    Summary Preliminary studies have suggested that a high salt diet may play a role in the development of autoimmune disease and possibly multiple sclerosis (MS). Promising clinical trial results for 2 new therapies for MS have been reported. Dimethyl fumarate, also known by its investigational name BG-12, became the third oral disease-modifying therapy for MS to be Food and Drug Administration (FDA)–approved in March 2013. Interestingly, dimethyl fumarate served as the active compound used for the treatment of psoriasis for decades. Alemtuzumab remains under investigation and is not currently FDA-approved for treatment of MS. Other drugs currently approved for alternative indications are being investigated for use in MS. Additionally, an investigation of alternative dosing strategies for glatiramer acetate suggests that patients may benefit from a higher dose formulation and less frequent medication administration. Advances in basic science research have identified another potential autoantigenic target in MS, KIR4.1, which may provide further insight into MS pathophysiology. PMID:24175156

  15. Multiple osteochondromas

    PubMed Central

    Bovée, Judith VMG

    2008-01-01

    Multiple osteochondromas (MO) is characterised by development of two or more cartilage capped bony outgrowths (osteochondromas) of the long bones. The prevalence is estimated at 1:50,000, and it seems to be higher in males (male-to-female ratio 1.5:1). Osteochondromas develop and increase in size in the first decade of life, ceasing to grow when the growth plates close at puberty. They are pedunculated or sessile (broad base) and can vary widely in size. The number of osteochondromas may vary significantly within and between families, the mean number of locations is 15–18. The majority are asymptomatic and located in bones that develop from cartilage, especially the long bones of the extremities, predominantly around the knee. The facial bones are not affected. Osteochondromas may cause pain, functional problems and deformities, especially of the forearm, that may be reason for surgical removal. The most important complication is malignant transformation of osteochondroma towards secondary peripheral chondrosarcoma, which is estimated to occur in 0.5–5%. MO is an autosomal dominant disorder and is genetically heterogeneous. In almost 90% of MO patients germline mutations in the tumour suppressor genes EXT1 or EXT2 are found. The EXT genes encode glycosyltransferases, catalyzing heparan sulphate polymerization. The diagnosis is based on radiological and clinical documentation, supplemented with, if available, histological evaluation of osteochondromas. If the exact mutation is known antenatal diagnosis is technically possible. MO should be distinguished from metachondromatosis, dysplasia epiphysealis hemimelica and Ollier disease. Osteochondromas are benign lesions and do not affect life expectancy. Management includes removal of osteochondromas when they give complaints. Removed osteochondromas should be examined for malignant transformation towards secondary peripheral chondrosarcoma. Patients should be well instructed and regular follow-up for early detection

  16. Albumin and multiple sclerosis.

    PubMed

    LeVine, Steven M

    2016-04-12

    Leakage of the blood-brain barrier (BBB) is a common pathological feature in multiple sclerosis (MS). Following a breach of the BBB, albumin, the most abundant protein in plasma, gains access to CNS tissue where it is exposed to an inflammatory milieu and tissue damage, e.g., demyelination. Once in the CNS, albumin can participate in protective mechanisms. For example, due to its high concentration and molecular properties, albumin becomes a target for oxidation and nitration reactions. Furthermore, albumin binds metals and heme thereby limiting their ability to produce reactive oxygen and reactive nitrogen species. Albumin also has the potential to worsen disease. Similar to pathogenic processes that occur during epilepsy, extravasated albumin could induce the expression of proinflammatory cytokines and affect the ability of astrocytes to maintain potassium homeostasis thereby possibly making neurons more vulnerable to glutamate exicitotoxicity, which is thought to be a pathogenic mechanism in MS. The albumin quotient, albumin in cerebrospinal fluid (CSF)/albumin in serum, is used as a measure of blood-CSF barrier dysfunction in MS, but it may be inaccurate since albumin levels in the CSF can be influenced by multiple factors including: 1) albumin becomes proteolytically cleaved during disease, 2) extravasated albumin is taken up by macrophages, microglia, and astrocytes, and 3) the location of BBB damage affects the entry of extravasated albumin into ventricular CSF. A discussion of the roles that albumin performs during MS is put forth.

  17. Preparing for Multiple Births

    MedlinePlus

    ... Video Games, and the Internet Preparing for Multiple Births KidsHealth > For Parents > Preparing for Multiple Births Print ... a combination of both. The Risks of Multiple Births The most common risk involved with multiple births ...

  18. Multiple Myeloma Symptoms

    MedlinePlus

    ... Treatment Center Finder Home » About Multiple Myeloma » Symptoms Multiple Myeloma Symptoms Multiple myeloma symptoms may vary by patient, ... to be managed or prevented. The most common multiple myeloma symptoms may include: Bone pain or bone fractures ...

  19. Multiple sclerosis - resources

    MedlinePlus

    Resources - multiple sclerosis ... The following organizations provide information on multiple sclerosis : Multiple Sclerosis Foundation -- www.msfocus.org National Institute of Neurological Disorders and Stroke -- www.ninds.nih.gov/disorders/multiple_sclerosis National ...

  20. Size Dependence of [n]Cycloparaphenylenes (n=5-12) in Electrochemical Oxidation.

    PubMed

    Kayahara, Eiichi; Fukayama, Kei; Nishinaga, Tohru; Yamago, Shigeru

    2016-06-21

    The oxidation processes of [n]cycloparaphenylenes ([n]CPPs) (n=5-12) were systematically investigated by cyclic and rotating disk electrode voltammetry. All CPPs underwent pseudo-reversible two-electron oxidation irrespective of ring size, forming the corresponding radical cations and then dications. The results were in sharp contrast to those observed for linear oligoparaphenylenes, which only undergo one-electron oxidation. The difference in the first and second oxidation potentials in the CPP oxidation was affected by the ring size and became more significant as the decrease of CPP size. In other words, while the first oxidation from neutral CPP to the radical cation occurred faster as the size of CPP becomes smaller, the second oxidation from the radical cation to dication exhibited opposite size dependence.

  1. [Nitric oxide].

    PubMed

    Rovira, I

    1995-01-01

    Nitric oxide was identified as the relaxing factor derived from the endothelium in 1987. Nitric oxide synthesis allows the vascular system to maintain a state of vasodilation, thereby regulating arterial pressure. Nitric oxide is also found in platelets, where it inhibits adhesion and aggregation; in the immune system, where it is responsible for the cytotoxic action of macrophages; and in the nervous system, where it acts as neurotransmitter. A deficit in endogenous synthesis of nitric oxide contributes to such conditions as essential arterial hypertension, pulmonary hypertension and heart disease. An excess of nitrous oxide induced by endotoxins and cytokinins, meanwhile, is believed to be responsible for hypotension in septic shock and for hyperdynamic circulatory state in cirrhosis of the liver. Nitric oxide has also been implicated in the rejection of transplanted organs and in cell damage after reperfusion. Inhaled nitrous oxide gas reduces pulmonary hypertension without triggering systemic hypotension in both experimental and clinical conditions. It also produces selective vasodilation when used to ventilate specific pulmonary areas, thereby improving the ventilation/perfusion ratio and, hence, oxygenation. Nitric oxide inhalation is effective in pulmonary hypertension-coincident with chronic obstructive lung disease, in persistent neonatal pulmonary hypertension and in pulmonary hypertension with congenital or acquired heart disease. Likewise, it reduces intrapulmonary shunt in acute respiratory failure and improves gas exchange. Under experimental conditions nitric oxide acts as a bronchodilator, although it seems to be less effective for this purpose in clinical use.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Molecular Level Coating of Metal Oxide Particles

    NASA Technical Reports Server (NTRS)

    McDaniel, Patricia R. (Inventor); St.Clair, Terry L. (Inventor)

    2002-01-01

    Polymer encapsulated metal oxide particles are prepared by combining a polyamide acid in a polar osmotic solvent with a metal alkoxide solution. The polymer was imidized and the metal oxide formed simultaneously in a refluxing organic solvent. The resulting polymer-metal oxide is an intimately mixed commingled blend, possessing, synergistic properties of both the polymer and preceramic metal oxide. The encapsulated metal oxide particles have multiple uses including, being useful in the production of skin lubricating creams, weather resistant paints, as a filler for paper. making ultraviolet light stable filled printing ink, being extruded into fibers or ribbons, and coatings for fibers used in the production of composite structural panels.

  3. Molecular Level Coating for Metal Oxide Particles

    NASA Technical Reports Server (NTRS)

    McDaniel, Patricia R. (Inventor); Saint Clair, Terry L. (Inventor)

    2000-01-01

    Polymer encapsulated metal oxide particles are prepared by combining a polyamide acid in a polar aprotic solvent with a metal alkoxide solution. The polymer was imidized and the metal oxide formed simultaneously in a refluxing organic solvent. The resulting polymer-metal oxide is an intimately mixed commingled blend, possessing synergistic properties of both the polymer and preceramic metal oxide. The encapsulated metal oxide particles have multiple uses including, being useful in the production of skin lubricating creams, weather resistant paints, as a filler for paper, making ultraviolet light stable filled printing ink, being extruded into fibers or ribbons, and coatings for fibers used in the production of composite structural panels.

  4. Molecular Level Coating of Metal Oxide Particles

    NASA Technical Reports Server (NTRS)

    McDaniel, Patricia R. (Inventor); St.Clair, Terry L. (Inventor)

    2002-01-01

    Polymer encapsulated metal oxide particles are prepared by combining a polyamide acid in a polar osmotic solvent with a metal alkoxide solution. The polymer was imidized and the metal oxide formed simultaneously in a refluxing organic solvent. The resulting polymer-metal oxide is an intimately mixed commingled blend, possessing, synergistic properties of both the polymer and preceramic metal oxide. The encapsulated metal oxide particles have multiple uses including, being useful in the production of skin lubricating creams, weather resistant paints, as a filler for paper. making ultraviolet light stable filled printing ink, being extruded into fibers or ribbons, and coatings for fibers used in the production of composite structural panels.

  5. Synthesis and characterization of homo- and heterobimetallic niobium{sup v} and tantalum{sup v} peroxo-polyaminocarboxylato complexes and their use as single or multiple molecular precursors for Nb-Ta mixed oxides

    SciTech Connect

    Bayot, Daisy . E-mail: devillers@chim.ucl.ac.be

    2005-09-15

    New water-soluble bimetallic peroxo complexes of niobium{sup V} and/or tantalum{sup V} with high-denticity polyaminocarboxylate ligands have been prepared, characterized from the spectroscopic point of view, and used as molecular precursors for Nb-Ta mixed oxides. Four new homobimetallic complexes (gu){sub 3}[Nb{sub 2}(O{sub 2}){sub 4}(dtpaO{sub 3})].3H{sub 2}O 1 (gu){sub 3}[Ta{sub 2}(O{sub 2}){sub 4}(dtpaO{sub 3})].5H{sub 2}O 2 (gu){sub 3}[Nb{sub 2}(O{sub 2}){sub 4}(HtthaO{sub 4})].2H{sub 2}O 4 and (gu){sub 3}[Ta{sub 2}(O{sub 2}){sub 4}(HtthaO{sub 4})].3H{sub 2}O 5 and the corresponding heterometallic complexes (gu){sub 3}[NbTa(O{sub 2}){sub 4}(dtpaO{sub 3})].2.5H{sub 2}O 3 and (gu){sub 3}[NbTa(O{sub 2}){sub 4}(HtthaO{sub 4)}].2H{sub 2}O 6 have been obtained. In these compounds, the in situ oxidation of the nitrogen atoms of the PAC ligands into N-oxide groups has been evidenced by IR spectroscopy and mass spectrometry. The thermal treatment of the homonuclear complexes in air at 700 or 800 deg. C, depending on the Ta content, provided Nb{sub 2}O{sub 5} or Ta{sub 2}O{sub 5} while the heteronuclear compounds led to the solid solution TaNbO{sub 5}. BET and SEM measurements have been carried out and comparison of the morphology of the samples prepared from homo- and heterometallic precursors is discussed.

  6. Combination of visible-light responsive heterogeneous and homogeneous photocatalysts for water oxidation.

    PubMed

    Fukuzumi, Shunichi; Kato, Satoshi; Suenobu, Tomoyoshi

    2011-10-28

    Bismuth vanadate (BiVO(4)), which is a visible-light responsive heterogeneous photocatalyst, was combined with homogeneous ruthenium complexes to increase the overall photocatalytic reactivity for water oxidation with a one-electron oxidant, [Co(III)(NH(3))(5)Cl](2+). Photoinduced electron transfer from the excited state of ruthenium(II) complexes to [Co(III)(NH(3))(5)Cl](2+) affords ruthenium(III) complexes which can oxidize water to oxygen with BiVO(4) under visible light irradiation. This journal is © the Owner Societies 2011

  7. Chasing the limits of the one electron approximation

    SciTech Connect

    Kędziera, Dariusz; Mentel, Łukasz M.

    2014-10-06

    Rapid progress in the development of computational methods for quantum chemistry is not properly balanced by the development of basis sets. Even in the case of few-electron systems it is hard to find basis set which are able to reproduce the ECG benchmarks with the mhartree accuracy. In this paper we show early work on improvements of the basis sets for small atomic and molecular systems. As a starting point the ground state of lithium atom and the lowest states of lithium dimer will be investigated. The exploratory optimization of the exponents of primitive gaussians will be based on even tempered scheme combined with CISD method.

  8. Excitonic Interfacial Proton-Coupled Electron Transfer Mechanism in the Photocatalytic Oxidation of Methanol to Formaldehyde on TiO2(110).

    PubMed

    Migani, Annapaola; Blancafort, Lluís

    2016-12-14

    CH3OH on a single-crystal rutile TiO2(110) surface is a widely studied model system for heterogeneous photocatalysis. Using spin-polarized density functional theory with a hybrid functional (HSE06), we study the photocatalytic oxidation of CH3OH adsorbed at a coordinately unsaturated Ti site as an excited-state process with triplet spin multiplicity. The oxidation to CH2O is stepwise and involves a CH3O intermediate. The first O-H dissociation step follows an excitonic interfacial proton-coupled electron transfer mechanism where the hole-electron (h-e) pair generated during the excitation is bound, and the h is transferred to the adsorbate. The O-H dissociation paths associated with other h-e pairs are unreactive, and the moderate experimental efficiency is due to the different reactivity of the h-e pairs. The excited-state CH3O intermediate further deactivates through a seam of intersection between the ground and excited states. It can follow three different paths, regeneration of adsorbed CH3OH or formation of the ground-state CH3O anion or an adsorbed CH2O radical anion. The third channel corresponds to photochemical CH2O formation from CH3OH, where a single photon induces one electron oxidation and transfer of two protons. These results expand the current view on the photocatalysis of CH3OH on TiO2(110) by highlighting the role of excitons and showing that adsorbed CH3OH may also be an active species in the photocatalytic oxidation to CH2O.

  9. Multiple System Atrophy (MSA)

    MedlinePlus

    Multiple system atrophy (MSA) Overview By Mayo Clinic Staff Multiple system atrophy (MSA) is a rare, degenerative neurological disorder ... progresses gradually and eventually leads to death. Multiple system atrophy care at Mayo Clinic . Mayo Clinic Footer ...

  10. Multiple aberrations in shared inflammatory and oxidative & nitrosative stress (IO&NS) pathways explain the co-association of depression and cardiovascular disorder (CVD), and the increased risk for CVD and due mortality in depressed patients.

    PubMed

    Maes, Michael; Ruckoanich, Piyanuj; Chang, Young Seun; Mahanonda, Nithi; Berk, Michael

    2011-04-29

    There is evidence that there is a bidirectional relationship between major depression and cardiovascular disorder (CVD): depressed patients are a population at risk for increased cardiac morbidity and mortality, and depression is more frequent in patients who suffer from CVD. There is also evidence that inflammatory and oxidative and nitrosative stress (IO&NS) pathways underpin the common pathophysiology of both CVD and major depression. Activation of these pathways may increase risk for both disorders and contribute to shared risk. The shared IO&NS pathways that may contribute to CVD and depression comprise the following: increased levels of pro-inflammatory cytokines, like interleukin-1β (IL-1β), IL-2, IL-6, IL-8, IL-12, tumor necrosis factor-α, and interferon-γ; T cell activation; increased acute phase proteins, like C-reactive protein, haptoglobin, fibrinogen and α1-antitrypsin; complement factors; increased LPS load through bacterial translocation and subsequent gut-derived inflammation; induction of indoleamine 2,3-dioxygenase with increased levels of tryptophan catabolites; decreased levels of antioxidants, like coenzyme Q10, zinc, vitamin E, glutathione and glutathione peroxidase; increased O&NS characterized by oxidative damage to low density lipoprotein (LDL) and phospholipid inositol, increased malondialdehyde, and damage to DNA and mitochondria; increased nitrosative stress; and decreased ω3 polyunsaturated fatty acids (PUFAs). The complex interplay between the abovementioned IO&NS pathways in depression results in pro-atherogenic effects and should be regarded as a risk factor to future clinical CVD and due mortality. We suggest that major depression should be added as a risk factor to the Charlson "comorbidity" index. It is advised that patients with (sub)chronic or recurrent major depression should routinely be assessed by serology tests to predict if they have an increased risk to cardiovascular disorders.

  11. Catalytic mechanism of water oxidation with single-site ruthenium-heteropolytungstate complexes.

    PubMed

    Murakami, Masato; Hong, Dachao; Suenobu, Tomoyoshi; Yamaguchi, Satoru; Ogura, Takashi; Fukuzumi, Shunichi

    2011-08-03

    Catalytic water oxidation to generate oxygen was achieved using all-inorganic mononuclear ruthenium complexes bearing Keggin-type lacunary heteropolytungstate, [Ru(III)(H(2)O)SiW(11)O(39)](5-) (1) and [Ru(III)(H(2)O)GeW(11)O(39)](5-) (2), as catalysts with (NH(4))(2)[Ce(IV)(NO(3))(6)] (CAN) as a one-electron oxidant in water. The oxygen atoms of evolved oxygen come from water as confirmed by isotope-labeled experiments. Cyclic voltammetric measurements of 1 and 2 at various pH's indicate that both complexes 1 and 2 exhibit three one-electron redox couples based on ruthenium center. The Pourbaix diagrams (plots of E(1/2) vs pH) support that the Ru(III) complexes are oxidized to the Ru(V)-oxo complexes with CAN. The Ru(V)-oxo complex derived from 1 was detected by UV-visible absorption, EPR, and resonance Raman measurements in situ as an active species during the water oxidation reaction. This indicates that the Ru(V)-oxo complex is involved in the rate-determining step of the catalytic cycle of water oxidation. The overall catalytic mechanism of water oxidation was revealed on the basis of the kinetic analysis and detection of the catalytic intermediates. Complex 2 exhibited a higher catalytic reactivity for the water oxidation with CAN than did complex 1.

  12. Oxidized limonene and oxidized linalool - concomitant contact allergy to common fragrance terpenes.

    PubMed

    Bråred Christensson, Johanna; Karlberg, Ann-Therese; Andersen, Klaus E; Bruze, Magnus; Johansen, Jeanne D; Garcia-Bravo, Begoña; Giménez Arnau, Ana; Goh, Chee-Leok; Nixon, Rosemary; White, Ian R

    2016-05-01

    Limonene and linalool are common fragrance terpenes. Both oxidized R-limonene and oxidized linalool have recently been patch tested in an international setting, showing contact allergy in 5.2% and 6.9% of dermatitis patients, respectively. To investigate concomitant reactions between oxidized R-limonene and oxidized linalool in consecutive dermatitis patients. Oxidized R-limonene 3.0% (containing limonene hydroperoxides 0.33%) and oxidized linalool 6% (linalool hydroperoxides 1%) in petrolatum were tested in 2900 consecutive dermatitis patients in Australia, Denmark, Singapore, Spain, Sweden, and the United Kingdom. A total of 281 patients reacted to either oxidized R-limonene or oxidized linalool. Of these, 25% had concomitant reactions to both compounds, whereas 29% reacted only to oxidized R-limonene and 46% only to oxidized linalool. Of the 152 patients reacting to oxidized R-limonene, 46% reacted to oxidized linalool, whereas 35% of the 200 patients reacting to oxidized linalool also reacted to oxidized R-limonene. The majority of the patients (75%) reacted to only one of the oxidation mixtures, thus supporting the specificity of the reactions. The concomitant reactions to the two fragrance allergens suggest multiple sensitizations, which most likely reflect the exposure to the different fragrance materials in various types of consumer products. This is in accordance with what is generally seen for patch test reactions to fragrance materials. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Demystified … Nitric oxide

    PubMed Central

    Stuart-Smith, K

    2002-01-01

    The discovery of nitric oxide (NO) demonstrated that cells could communicate via the manufacture and local diffusion of an unstable lipid soluble molecule. Since the original demonstration of the vascular relaxant properties of endothelium derived NO, this fascinating molecule has been shown to have multiple, complex roles within many biological systems. This review cannot hope to cover all of the recent advances in NO biology, but seeks to place the discovery of NO in its historical context, and show how far our understanding has come in the past 20 years. The role of NO in mitochondrial respiration, and consequently in oxidative stress, is described in detail because these processes probably underline the importance of NO in the development of disease. PMID:12456772

  14. Iron Oxides

    SciTech Connect

    Qafoku, Nikolla; Amonette, James E.

    2016-09-19

    Abstract: Fe oxides are common clay-sized oxide, oxyhydroxide and hydroxide soil minerals. They are compounds of Fe, O, and H that have structures based on close-packed arrays of O. The octahedral and tetrahedral cavities within these arrays are filled with either Fe3+ or Fe2+ to form Fe(O/OH)6, FeO6, or FeO4 structural units. All of the naturally occurring Fe oxide minerals usually undergo some degree of isomorphous substitution of other metal ions for Fe in their structures. Relatively simple techniques may be used to identify Fe oxides in the field based on their typical colors and magnetic properties. In the laboratory, a variety of instrumental techniques can be used to confirm phase identity and to quantify amount. Of these, X-ray diffraction, infrared spectroscopy, electron microscopy, thermal analysis, and Mössbauer spectroscopy are the most commonly used techniques. As oxides, the functional groups on their surfaces may have positive, negative, or no charge depending on pH and on the concentration and nature of other ions in the contact solution. A net positive surface charge usually is observed in soils because Fe oxides have a point-of-zero-charge in the neutral or slightly basic pHs. The functional groups on the surface form complexes with cations and anions from the aqueous phase. Their sorption and electron-buffering properties significantly affect the geochemical cycles of almost all elements having agronomic or environmental significance.

  15. The role of Capon in multiple myeloma.

    PubMed

    Shen, Yaodong; Liu, Haiyan; Gu, Siyu; Wei, Ziwei; Liu, Hong

    2017-07-01

    Capon is a ligand protein of nitric oxide synthase 1. Recently, studies have shown that Capon is involved in the development of tumors. It is independent of the regulation of nitric oxide synthase 1 in this process. At the same time, studies have found that nitric oxide synthase 1 is expressed in multiple myeloma, but its role in the development and progression of myeloma remains unclear. In this study, we found that there was a different expression of Capon between the normal multiple myeloma cells and the adherent multiple myeloma cells. In the process of myeloma cell proliferation, the reduced expression of Capon reduces the arrest of the cell cycle in the G1 phase and promotes the proliferation of myeloma cells. Cell adhesion-mediated drug resistance is one of the most important factors, which affect the chemotherapy effect of multiple myeloma. If the expression of Capon is decreased, myeloma cells are adhered to fibronectin or bone marrow stromal cells (bone marrow mesenchymal stem cells). In addition, the sensitivity of the cell line to chemotherapeutic agents was reduced after silencing Capon in the myeloma cell line which was adhered to bone marrow mesenchymal stem cells. We also found that reduced expression of Capon resulted in the activation of the AKT signaling pathway. In conclusion, these results may be helpful in studying the role of Capon in multiple myeloma.

  16. Haemophilus influenzae and oxidative stress

    PubMed Central

    Harrison, Alistair; Bakaletz, Lauren O.; Munson, Robert S.

    2012-01-01

    Haemophilus influenzae is a commensal of the human upper respiratory tract. H. influenzae can, however, move out of its commensal niche and cause multiple respiratory tract diseases. Such diseases include otitis media in young children, as well as exacerbations of chronic obstructive pulmonary disease (COPD), sinusitis, conjunctivitis, and bronchitis. During the course of colonization and infection, H. influenzae must withstand oxidative stress generated by multiple reactive oxygen species produced endogenously, by other co-pathogens and by host cells. H. influenzae has, therefore, evolved multiple mechanisms that protect the cell against oxygen-generated stresses. In this review, we will describe these systems relative to the well-described systems in Escherichia coli. Moreover, we will compare how H. influenzae combats the effect of oxidative stress as a necessary phenotype for its roles as both a successful commensal and pathogen. PMID:22919631

  17. Multiple exciton collection in a sensitized photovoltaic system.

    PubMed

    Sambur, Justin B; Novet, Thomas; Parkinson, B A

    2010-10-01

    Multiple exciton generation, the creation of two electron-hole pairs from one high-energy photon, is well established in bulk semiconductors, but assessments of the efficiency of this effect remain controversial in quantum-confined systems like semiconductor nanocrystals. We used a photoelectrochemical system composed of PbS nanocrystals chemically bound to TiO(2) single crystals to demonstrate the collection of photocurrents with quantum yields greater than one electron per photon. The strong electronic coupling and favorable energy level alignment between PbS nanocrystals and bulk TiO(2) facilitate extraction of multiple excitons more quickly than they recombine, as well as collection of hot electrons from higher quantum dot excited states. Our results have implications for increasing the efficiency of photovoltaic devices by avoiding losses resulting from the thermalization of photogenerated carriers.

  18. Regulation of drug metabolism and toxicity by multiple factors of genetics, epigenetics, lncRNAs, gut microbiota, and diseases: a meeting report of the 21(st) International Symposium on Microsomes and Drug Oxidations (MDO).

    PubMed

    Yu, Ai-Ming; Ingelman-Sundberg, Magnus; Cherrington, Nathan J; Aleksunes, Lauren M; Zanger, Ulrich M; Xie, Wen; Jeong, Hyunyoung; Morgan, Edward M; Turnbaugh, Peter J; Klaassen, Curtis D; Bhatt, Aadra P; Redinbo, Matthew R; Hao, Pengying; Waxman, David J; Wang, Li; Zhong, Xiao-Bo

    2017-03-01

    Variations in drug metabolism may alter drug efficacy and cause toxicity; better understanding of the mechanisms and risks shall help to practice precision medicine. At the 21(st) International Symposium on Microsomes and Drug Oxidations held in Davis, California, USA, in October 2-6, 2016, a number of speakers reported some new findings and ongoing studies on the regulation mechanisms behind variable drug metabolism and toxicity, and discussed potential implications to personalized medications. A considerably insightful overview was provided on genetic and epigenetic regulation of gene expression involved in drug absorption, distribution, metabolism, and excretion (ADME) and drug response. Altered drug metabolism and disposition as well as molecular mechanisms among diseased and special populations were presented. In addition, the roles of gut microbiota in drug metabolism and toxicology as well as long non-coding RNAs in liver functions and diseases were discussed. These findings may offer new insights into improved understanding of ADME regulatory mechanisms and advance drug metabolism research.

  19. Operation of the Oxide Washer for Water-Washing Solubles out of Impure Pu Oxide

    SciTech Connect

    Dodson, K E; Close, W L; Krikorian, O H; Summers III, H V

    2006-01-30

    An evaluation has been made for using the Oxide Washer to wash water-soluble materials out of impure Pu oxide. It is found that multiple washes are needed to reduce the water-soluble materials to very low levels in the impure Pu oxides. The removal of the wash water from the Oxide Washer is accompanied by particulates of the impure Pu oxide, which subsequently need to be filtered out. In spite of the additional filtration needed, the overall level of manpower required for processing is still only about one third of that for an all-manual operation.

  20. Kinetic evidence for rapid oxidation of (-)-epicatechin by human myeloperoxidase

    SciTech Connect

    Spalteholz, Holger; Furtmueller, Paul Georg; Jakopitsch, Christa; Obinger, Christian; Schewe, Tankred; Sies, Helmut; Arnhold, Juergen

    2008-07-11

    Apocynin has been reported to require dimerization by myeloperoxidase (MPO) to inhibit leukocyte NADPH oxidase. (-)-Epicatechin, a dietary flavan-3-ol, has been identified as a 'prodrug' of apocynin-like metabolites that inhibit endothelial NADPH oxidase activity and elevate the cellular level of nitric oxide. Since (-)-epicatechin has tentatively been identified as substrate of MPO, we studied the one-electron oxidation of (-)-epicatechin by MPO. By using multi-mixing stopped-flow technique, we demonstrate that (-)-epicatechin is one of the most efficient electron donors for heme peroxidases investigated so far. Second order rate constants for the (-)-epicatechin-mediated conversion of MPO-compound I to compound II and compound II to resting enzyme were estimated to be 1.9 x 10{sup 7} and 4.5 x 10{sup 6} M{sup -1} s{sup -1}, respectively (pH 7, 25 deg. C). The data indicate that (-)-epicatechin is capable of undergoing fast MPO-mediated one-electron oxidation.

  1. Biomarkers of exposure to endogenous oxidative and aldehyde stress.

    PubMed

    Bruce, W Robert; Lee, Owen; Liu, Zhen; Marcon, Norman; Minkin, Salomon; O'Brien, Peter J

    2011-08-01

    We observed an unexpectedly strong association of three different endogenous aldehydes and noted that the association could be explained by multiple reactions in which oxidative stress increased the formation of endogenous aldehydes and endogenous aldehydes increased oxidative stress. These interactions make it reasonable to assess multiple exposures to endogenous oxidative and aldehyde stress with less specific measures such as advanced glycation end-products or protein carbonyls.

  2. Oxidised guanidinohydantoin (Ghox) and spiroiminodihydantoin (Sp) are major products of iron- and copper-mediated 8-oxo-7,8-dihydroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine oxidation.

    PubMed

    White, Blánaid; Tarun, Maricar C; Gathergood, Nicholas; Rusling, James F; Smyth, Malcolm R

    2005-12-01

    8-Oxo-7,8-dihydroguanine (8-oxoGua), an important biomarker of DNA damage in oxidatively generated stress, is highly reactive towards further oxidation. Much work has been carried out to investigate the oxidation products of 8-oxoGua by one-electron oxidants, singlet oxygen, and peroxynitrite. This report details for the first time, the iron- and copper-mediated Fenton oxidation of 8-oxoGua and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo). Oxidised guanidinohydantoin (Gh(ox)) was detected as the major product of oxidation of 8-oxoGua with iron or copper and hydrogen peroxide, both at pH 7 and pH 11. Oxaluric acid was identified as a final product of 8-oxoGua oxidation. 8-oxodGuo was subjected to oxidation under the same conditions as 8-oxoGua. However, dGh(ox) was not generated. Instead, spiroiminodihydantoin (Sp) was detected as the major product for both iron and copper mediated oxidation at pH 7. It was proposed that the oxidation of 8-oxoGua was initiated by its one-electron oxidation by the metal species, which leads to the reactive intermediate 8-oxoGua (+), which readily undergoes further oxidation. The product of 8-oxoGua and 8-oxodGuo oxidation was determined by the 2'-deoxyribose moiety of the 8-oxodGuo, not whether copper or iron was the metal involved in the oxidation.

  3. A many-body states picture of electronic friction: The case of multiple orbitals and multiple electronic states

    NASA Astrophysics Data System (ADS)

    Dou, Wenjie; Subotnik, Joseph E.

    2016-08-01

    We present a very general form of electronic friction as present when a molecule with multiple orbitals hybridizes with a metal electrode. To develop this picture of friction, we embed the quantum-classical Liouville equation (QCLE) within a classical master equation (CME). Thus, this article extends our previous work analyzing the case of one electronic level, as we may now treat the case of multiple levels and many electronic molecular states. We show that, in the adiabatic limit, where electron transitions are much faster than nuclear motion, the QCLE-CME reduces to a Fokker-Planck equation, such that nuclei feel an average force as well as friction and a random force—as caused by their interaction with the metallic electrons. Finally, we show numerically and analytically that our frictional results agree with other published results calculated using non-equilibrium Green's functions. Numerical recipes for solving this QCLE-CME will be provided in a subsequent paper.

  4. A many-body states picture of electronic friction: The case of multiple orbitals and multiple electronic states.

    PubMed

    Dou, Wenjie; Subotnik, Joseph E

    2016-08-07

    We present a very general form of electronic friction as present when a molecule with multiple orbitals hybridizes with a metal electrode. To develop this picture of friction, we embed the quantum-classical Liouville equation (QCLE) within a classical master equation (CME). Thus, this article extends our previous work analyzing the case of one electronic level, as we may now treat the case of multiple levels and many electronic molecular states. We show that, in the adiabatic limit, where electron transitions are much faster than nuclear motion, the QCLE-CME reduces to a Fokker-Planck equation, such that nuclei feel an average force as well as friction and a random force-as caused by their interaction with the metallic electrons. Finally, we show numerically and analytically that our frictional results agree with other published results calculated using non-equilibrium Green's functions. Numerical recipes for solving this QCLE-CME will be provided in a subsequent paper.

  5. Oxidation of hypotaurine and cysteine sulphinic acid by peroxynitrite

    PubMed Central

    2005-01-01

    Peroxynitrite mediates the oxidation of the sulphinic group of both HTAU (hypotaurine) and CSA (cysteine sulphinic acid), producing the respective sulphonates, TAU (taurine) and CA (cysteic acid). The reaction is associated with extensive oxygen uptake, suggesting that HTAU and CSA are oxidized by the one-electron transfer mechanism to sulphonyl radicals, which may initiate an oxygen-dependent radical chain reaction with the sulphonates as final products. Besides the one-electron mechanism, HTAU and CSA can be oxidized by the two-electron pathway, leading directly to sulphonate formation without oxygen consumption. The apparent second-order rate constants for the direct reaction of peroxynitrite with HTAU and CSA at pH 7.4 and 25 °C are 77.4±5 and 76.4±9 M−1·s−1 respectively. For both sulphinates, the apparent second-order rate constants increase sharply with decrease in pH, and the sigmoidal curves obtained are consistent with peroxynitrous acid as the species responsible for sulphinate oxidation. The kinetic data, together with changes in oxygen uptake, sulphinate depletion, sulphonate production, and product distribution of nitrite and nitrate, suggest that oxidation of sulphinates by peroxynitrite may take place by the two reaction pathways whose relative importance depends on reagent concentrations and pH value. In the presence of bicarbonate, the direct reaction of sulphinates with peroxynitrite is inhibited and the oxidative reaction probably involves only the radicals •NO2 and CO3•−, generated by decomposition of the peroxynitrite-CO2 adduct. PMID:15740460

  6. Oxygen and Silver Clusters: Transition from Chemisorption to Oxidation

    NASA Astrophysics Data System (ADS)

    Schmidt, M.; Masson, A.; Bréchignac, C.

    2003-12-01

    We use the adsorption probabilities of molecular nitrogen and oxygen to study the physi- and chemisorption on small silver particles. The physisorption of nitrogen is governed by the structure of the particle surface. The sticking of oxygen additionally involves the electronic configuration of the metal cluster. At 77K molecular oxygen sticks chemisorbed to the particles with a transfer of one electron. At temperatures above 105K the chemisorption transforms into oxidation, invoking the dissociation of the oxygen molecule and the loss of a single oxygen atom.

  7. Oxygen and silver clusters: transition from chemisorption to oxidation.

    PubMed

    Schmidt, M; Masson, A; Bréchignac, C

    2003-12-12

    We use the adsorption probabilities of molecular nitrogen and oxygen to study the physi- and chemisorption on small silver particles. The physisorption of nitrogen is governed by the structure of the particle surface. The sticking of oxygen additionally involves the electronic configuration of the metal cluster. At 77 K molecular oxygen sticks chemisorbed to the particles with a transfer of one electron. At temperatures above 105 K the chemisorption transforms into oxidation, invoking the dissociation of the oxygen molecule and the loss of a single oxygen atom.

  8. Surface Mn(II) oxidation actuated by a multicopper oxidase in a soil bacterium leads to the formation of manganese oxide minerals

    PubMed Central

    Zhang, Zhen; Zhang, Zhongming; Chen, Hong; Liu, Jin; Liu, Chang; Ni, Hong; Zhao, Changsong; Ali, Muhammad; Liu, Fan; Li, Lin

    2015-01-01

    In this manuscript, we report that a bacterial multicopper oxidase (MCO266) catalyzes Mn(II) oxidation on the cell surface, resulting in the surface deposition of Mn(III) and Mn(IV) oxides and the gradual formation of bulky oxide aggregates. These aggregates serve as nucleation centers for the formation of Mn oxide micronodules and Mn-rich sediments. A soil-borne Escherichia coli with high Mn(II)-oxidizing activity formed Mn(III)/Mn(IV) oxide deposit layers and aggregates under laboratory culture conditions. We engineered MCO266 onto the cell surfaces of both an activity-negative recipient and wild-type strains. The results confirmed that MCO266 governs Mn(II) oxidation and initiates the formation of deposits and aggregates. By contrast, a cell-free substrate, heat-killed strains, and intracellularly expressed or purified MCO266 failed to catalyze Mn(II) oxidation. However, purified MCO266 exhibited Mn(II)-oxidizing activity when combined with cell outer membrane component (COMC) fractions in vitro. We demonstrated that Mn(II) oxidation and aggregate formation occurred through an oxygen-dependent biotic transformation process that requires a certain minimum Mn(II) concentration. We propose an approximate electron transfer pathway in which MCO266 transfers only one electron to convert Mn(II) to Mn(III) and then cooperates with other COMC electron transporters to transfer the other electron required to oxidize Mn(III) to Mn(IV). PMID:26039669

  9. Fatty acid transduction of nitric oxide signaling: multiple nitrated unsaturated fatty acid derivatives exist in human blood and urine and serve as endogenous peroxisome proliferator-activated receptor ligands.

    PubMed

    Baker, Paul R S; Lin, Yiming; Schopfer, Francisco J; Woodcock, Steven R; Groeger, Alison L; Batthyany, Carlos; Sweeney, Scott; Long, Marshall H; Iles, Karen E; Baker, Laura M S; Branchaud, Bruce P; Chen, Yuqing E; Freeman, Bruce A

    2005-12-23

    Mass spectrometric analysis of human plasma and urine revealed abundant nitrated derivatives of all principal unsaturated fatty acids. Nitrated palmitoleic, oleic, linoleic, linolenic, arachidonic and eicosapentaenoic acids were detected in concert with their nitrohydroxy derivatives. Two nitroalkene derivatives of the most prevalent fatty acid, oleic acid, were synthesized (9- and 10-nitro-9-cis-octadecenoic acid; OA-NO2), structurally characterized and determined to be identical to OA-NO2 found in plasma, red cells, and urine of healthy humans. These regioisomers of OA-NO2 were quantified in clinical samples using 13C isotope dilution. Plasma free and esterified OA-NO2 concentrations were 619 +/- 52 and 302 +/- 369 nm, respectively, and packed red blood cell free and esterified OA-NO2 was 59 +/- 11 and 155 +/- 65 nm. The OA-NO2 concentration of blood is approximately 50% greater than that of nitrated linoleic acid, with the combined free and esterified blood levels of these two fatty acid derivatives exceeding 1 microm. OA-NO2 is a potent ligand for peroxisome proliferator activated receptors at physiological concentrations. CV-1 cells co-transfected with the luciferase gene under peroxisome proliferator-activated receptor (PPAR) response element regulation, in concert with PPARgamma, PPARalpha, or PPARdelta expression plasmids, showed dose-dependent activation of all PPARs by OA-NO2. PPARgamma showed the greatest response, with significant activation at 100 nm, while PPARalpha and PPARdelta were activated at approximately 300 nm OA-NO2. OA-NO2 also induced PPAR gamma-dependent adipogenesis and deoxyglucose uptake in 3T3-L1 preadipocytes at a potency exceeding nitrolinoleic acid and rivaling synthetic thiazo-lidinediones. These data reveal that nitrated fatty acids comprise a class of nitric oxide-derived, receptor-dependent, cell signaling mediators that act within physiological concentration ranges.

  10. Three-Dimensional Normal Human Neutral Progenitor Tissue-Like Assemblies: A Model for Persistent Varicella-Zoster Virus Infection and Platform to Study Oxidate Stress and Damage in Multiple Hit Scenarios

    NASA Technical Reports Server (NTRS)

    Goodwin, Thomas J.; McCarthy, M.; Osterrieder, N.; Cohrs, R. J.; Kaufer, B. B.

    2014-01-01

    The environment of space results in a multitude of challenges to the human physiology that present barriers to extended habitation and exploration. Over 40 years of investigation to define countermeasures to address space flight adaptation has left gaps in our knowledge regarding mitigation strategies partly due to the lack of investigative tools, monitoring strategies, and real time diagnostics to understand the central causative agent(s) responsible for physiologic adaptation and maintaining homeostasis. Spaceflight-adaptation syndrome is the combination of space environmental conditions and the synergistic reaction of the human physiology. Our work addresses the role of oxidative stress and damage (OSaD) as a negative and contributing Risk Factor (RF) in the following areas of combined spaceflight related dysregulation: i) radiation induced cellular damage [1], [2] ii) immune impacts and the inflammatory response [3], [4] and iii) varicella zoster virus (VZV) reactivation [5]. Varicella-zoster (VZV)/Chicken Pox virus is a neurotropic human alphaherpes virus resulting in varicella upon primary infection, suppressed by the immune system becomes latent in ganglionic neurons, and reactivates under stress events to re-express in zoster and possibly shingles. Our laboratory has developed a complex three-dimensional (3D) normal human neural tissue model that emulates several characteristics of the human trigeminal ganglia (TG) and allows the study of combinatorial experimentation which addresses, simultaneously, OSaD associated with Spaceflight adaptation and habitation [6]. By combining the RFs of microgravity, radiation, and viral infection we will demonstrate that living in the space environment leads to significant physiological consequences for the peripheral and subsequently the central nervous system (PNS, CNS) associated with OSaD generation and consequentially endangers long-duration and exploration-class missions.

  11. Theoretical investigations on oxidative stability of solvents and oxidative decomposition mechanism of ethylene carbonate for lithium ion battery use.

    PubMed

    Xing, Lidan; Li, Weishan; Wang, Chaoyang; Gu, Fenglong; Xu, Mengqing; Tan, Chunlin; Yi, Jin

    2009-12-31

    The electrochemical oxidative stability of solvent molecules used for lithium ion battery, ethylene carbonate (EC), propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate in the forms of simple molecule and coordination with anion PF(6)(-), is compared by using density functional theory at the level of B3LYP/6-311++G (d, p) in gas phase. EC is found to be the most stable against oxidation in its simple molecule. However, due to its highest dielectric constant among all the solvent molecules, EC coordinates with PF(6)(-) most strongly and reaches cathode most easily, resulting in its preferential oxidation on cathode. Detailed oxidative decomposition mechanism of EC is investigated using the same level. Radical cation EC(*+) is generated after one electron oxidation reaction of EC and there are five possible pathways for the decomposition of EC(*+) forming CO(2), CO, and various radical cations. The formation of CO is more difficult than CO(2) during the initial decomposition of EC(*+) due to the high activation energy. The radical cations are reduced and terminated by gaining one electron from anode or solvent molecules, forming aldehyde and oligomers of alkyl carbonates including 2-methyl-1,3-dioxolane, 1,3,6-trioxocan-2-one, 1,4,6,9-tetraoxaspiro[4.4]nonane, and 1,4,6,8,11-pentaoxaspiro[4.6]undecan-7-one. The calculation in this paper gives a detailed explanation on the experimental findings that have been reported in literatures and clarifies the mechanism on the oxidative decomposition of EC.

  12. Oxide Thermoelectrics

    SciTech Connect

    Singh, David J

    2008-01-01

    Thermoelectricity in oxides, especially NaxCoO2 and related materials, is discussed from the point of view of first principles calculations and Boltzmann transport theory. The electronic structure of this material is exceptional in that it has a combination of very narrow bands and strong hybridization between metal d states and ligand p states. As shown within the framework of conventional Boltzmann transport theory, this leads to high Seebeck coefficients even at metallic carrier densities. This suggests a strategy of searching for other narrow band oxides that can be doped metallic with mobile carriers. Some possible avenues for finding such materials are suggested.

  13. Oxidation catalyst

    DOEpatents

    Ceyer, Sylvia T.; Lahr, David L.

    2010-11-09

    The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

  14. Multiple-Ring Digital Communication Network

    NASA Technical Reports Server (NTRS)

    Kirkham, Harold

    1992-01-01

    Optical-fiber digital communication network to support data-acquisition and control functions of electric-power-distribution networks. Optical-fiber links of communication network follow power-distribution routes. Since fiber crosses open power switches, communication network includes multiple interconnected loops with occasional spurs. At each intersection node is needed. Nodes of communication network include power-distribution substations and power-controlling units. In addition to serving data acquisition and control functions, each node acts as repeater, passing on messages to next node(s). Multiple-ring communication network operates on new AbNET protocol and features fiber-optic communication.

  15. Multiple-Ring Digital Communication Network

    NASA Technical Reports Server (NTRS)

    Kirkham, Harold

    1992-01-01

    Optical-fiber digital communication network to support data-acquisition and control functions of electric-power-distribution networks. Optical-fiber links of communication network follow power-distribution routes. Since fiber crosses open power switches, communication network includes multiple interconnected loops with occasional spurs. At each intersection node is needed. Nodes of communication network include power-distribution substations and power-controlling units. In addition to serving data acquisition and control functions, each node acts as repeater, passing on messages to next node(s). Multiple-ring communication network operates on new AbNET protocol and features fiber-optic communication.

  16. ALTERNATIVE OXIDANTS

    EPA Science Inventory

    This chapter reports on the efforts of the USEPA to study chloramines, chlorine dioxide and ozone as alternative oxidants/disinfectants to chlorine for the control of disinfection by-rpdocuts (DBPs) in drinking water. It examines the control of DBPs like trihalomethanes and haloa...

  17. Propylene oxide

    Integrated Risk Information System (IRIS)

    Propylene oxide ; CASRN 75 - 56 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  18. Merphos oxide

    Integrated Risk Information System (IRIS)

    Merphos oxide ; CASRN 78 - 48 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effe

  19. Thallium oxide

    Integrated Risk Information System (IRIS)

    Thallium oxide ; CASRN 1314 - 32 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic E

  20. Ethylene oxide

    Integrated Risk Information System (IRIS)

    EPA / 635 / R - 16 / 350Fc www.epa.gov / iris Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide EXECUTIVE SUMMARY ( CASRN 75 - 21 - 8 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) December 201 6 National Center for Environmental Assessment Office

  1. Nitric oxide

    Integrated Risk Information System (IRIS)

    Nitric oxide ; CASRN 10102 - 43 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  2. Electrochemical oxidation of wine polyphenols in the presence of sulfur dioxide.

    PubMed

    Makhotkina, Olga; Kilmartin, Paul A

    2013-06-12

    Electrochemical oxidation of three representative wine polyphenols (catechin, caffeic acid, and quercetin) in the presence of sulfur dioxide in a model wine solution (pH = 3.3) was investigated. The oxidation was undertaken using chronoamperometry at a rotating glassy carbon rod electrode, and the reaction products were characterized by HPLC-MS. The mechanism of electrochemical oxidation of polyphenols in the presence of sulfur dioxide was proposed to be an ECEC mechanism. The polyphenols first underwent a one-electron oxidation to a semiquinone radical, which can be reduced back to the original polyphenol by sulfur dioxide, or further oxidized to the quinone form. In the cases of caffeic acid and catechin, the quinone combined with sulfur dioxide and produced new derivatives. The quercetin quinone underwent further chemical transformations, producing several new compounds. The proposed mechanisms were confirmed by digital simulation of cyclic voltammograms.

  3. Synthesis, spectral characterization, structures, and oxidation state distributions in [(corrolato)Fe(III)(NO)](n) (n = 0, +1, -1) complexes.

    PubMed

    Sinha, Woormileela; Deibel, Naina; Agarwala, Hemlata; Garai, Antara; Schweinfurth, David; Purohit, Chandra Shekhar; Lahiri, Goutam Kumar; Sarkar, Biprajit; Kar, Sanjib

    2014-02-03

    Two novel trans-A2B-corroles and three [(corrolato){FeNO}(6)] complexes have been prepared and characterized by various spectroscopic techniques. In the native state, all these [(corrolato){FeNO}(6)] species are diamagnetic and display "normal" chemical shifts in the (1)H NMR spectra. For two of the structurally characterized [(corrolato){FeNO}(6)] derivatives, the Fe-N-O bond angles are 175.0(4)° and 171.70(3)° (DFT: 179.94°), respectively, and are designated as linear nitrosyls. The Fe-N (NO) bond distances are 1.656(4) Å and 1.650(3) Å (DFT: 1.597 Å), which point toward a significant Fe(III) → NO back bonding. The NO bond lengths are 1.159(5) Å and 1.162(3) Å (DFT: 1.162 Å) and depict their elongated character. These structural data are typical for low-spin Fe(III). Electrochemical measurements show the presence of a one-electron oxidation and a one-electron reduction process for all the complexes. The one-electron oxidized species of a representative [(corrolato){FeNO}(6)] complex exhibits ligand to ligand charge transfer (LLCT) transitions (cor(π) → cor(π*)) at 399 and 637 nm, and the one-electron reduced species shows metal to ligand charge transfer (MLCT) transition (Fe(dπ) → cor(π*)) in the UV region at 330 nm. The shift of the νNO stretching frequency of a representative [(corrolato){FeNO}(6)] complex on one-electron oxidation occurs from 1782 cm(-1) to 1820 cm(-1), which corresponds to 38 cm(-1), and on one-electron reduction occurs from 1782 cm(-1) to 1605 cm(-1), which corresponds to 177 cm(-1). The X-band electron paramagnetic resonance (EPR) spectrum of one-electron oxidation at 295 K in CH2Cl2/0.1 M Bu4NPF6 displays an isotropic signal centered at g = 2.005 with a peak-to-peak separation of about 15 G. The in situ generated one-electron reduced species in CH2Cl2/0.1 M Bu4NPF6 at 295 K shows an isotropic signal centered at g = 2.029. The 99% contribution of corrole to the HOMO of native species indicates that oxidation occurs from

  4. Domestic Violence - Multiple Languages

    MedlinePlus

    ... Are Here: Home → Multiple Languages → All Health Topics → Domestic Violence URL of this page: https://medlineplus.gov/languages/ ... V W XYZ List of All Topics All Domestic Violence - Multiple Languages To use the sharing features on ...

  5. MultipleColposcopyJCO

    Cancer.gov

    Performing multiple biopsies during a procedure known as colposcopy—visual inspection of the cervix—is more effective than performing only a single biopsy of the worst-appearing area for detecting cervical cancer precursors. This multiple biopsy approach

  6. Panic Disorder - Multiple Languages

    MedlinePlus

    ... Are Here: Home → Multiple Languages → All Health Topics → Panic Disorder URL of this page: https://medlineplus.gov/languages/ ... V W XYZ List of All Topics All Panic Disorder - Multiple Languages To use the sharing features on ...

  7. Twins, Triplets, Multiple Births

    MedlinePlus

    ... deliver by C-section, especially if there are three babies or more. Parenting multiples can be a challenge. Volunteer help and support groups for parents of multiples can help. Dept. of Health and ...

  8. Whooping Cough - Multiple Languages

    MedlinePlus

    ... Are Here: Home → Multiple Languages → All Health Topics → Whooping Cough URL of this page: https://medlineplus.gov/languages/ ... V W XYZ List of All Topics All Whooping Cough - Multiple Languages To use the sharing features on ...

  9. Salmonella Infections - Multiple Languages

    MedlinePlus

    ... Are Here: Home → Multiple Languages → All Health Topics → Salmonella Infections URL of this page: https://medlineplus.gov/ ... V W XYZ List of All Topics All Salmonella Infections - Multiple Languages To use the sharing features ...

  10. Impaired Driving - Multiple Languages

    MedlinePlus

    ... Are Here: Home → Multiple Languages → All Health Topics → Impaired Driving URL of this page: https://medlineplus.gov/languages/ ... V W XYZ List of All Topics All Impaired Driving - Multiple Languages To use the sharing features on ...

  11. Postpartum Depression - Multiple Languages

    MedlinePlus

    ... Are Here: Home → Multiple Languages → All Health Topics → Postpartum Depression URL of this page: https://medlineplus.gov/languages/ ... V W XYZ List of All Topics All Postpartum Depression - Multiple Languages To use the sharing features on ...

  12. Lipid oxidation in the skin.

    PubMed

    Niki, Etsuo

    2015-01-01

    Skin is the largest organ of the body and exerts several physiological functions such as a protective barrier against moisture loss and noxious agents including ultraviolet irradiation. Oxidation of skin may impair such functions and induce skin disorders including photoaging and skin cancer. Skin surface lipids, a mixture of sebaceous and epidermal lipids, have unique species and fatty acid profile. The major unsaturated lipids are squalene, sebaleic aicd, linoleic acid, and cholesterol. Singlet oxygen and ozone as well as free radicals and enzymes are important oxidants for skin lipids. Squalene is the major target for singlet oxygen, giving rise to twelve regio-isomeric squalene hydroperoxides. Ultraviolet radiation activates lipoxygenase and cyclooxygenase, inducing specific enzymatic oxidation of lipids. Free radical mediated lipid peroxidation gives multiple oxidation products. Lipid oxidation products produced by these mechanisms are observed in human skin and induce various skin diseases, but in contrast to plasma and other tissues, identification and quantitative measurement of lipid oxidation products in skin are scarce and should be the subjects of future studies.

  13. Oxidation of guanine in double-stranded DNA by [Ru(bpy)2dppz]Cl2 in cationic reverse micelles.

    PubMed

    Evans, Sarah E; Grigoryan, Armine; Szalai, Veronika A

    2007-10-01

    DNA oxidation has been investigated in the medium of cationic reverse micelles (RMs). The oxidative chemistry is photochemically initiated using the DNA intercalator bis(bipyridine)dipyridophenazine ruthenium(II) chloride ([Ru(bpy)2dppz]Cl2) bound to duplex DNA in the RMs. High-resolution polyacrylamide gel electrophoresis (PAGE) is used to reveal and quantify guanine (G) oxidation products, including 8-oxo-7,8-dihydroguanine (8OG). In buffer solution, the addition of the oxidative quenchers potassium ferricyanide or pentaamminechlorocobalt(III) dichloride leads to an increase in the amount of piperidine-labile G oxidation products generated via one-electron oxidation. In RMs, however, the yield of oxidatively generated damage is attenuated. With or without ferricyanide quencher in the RMs, the yield of oxidatively generated products is approximately the same. Inclusion of the cationic quencher [CoCl(NH3)5]2+ in the RMs increases the amount of oxidation products generated but not to the extent that it does in buffer solution. Under anaerobic conditions, all of the samples in RMs, with or without added oxidative quenchers, show decreased levels of piperidine-labile oxidation products, suggesting that the primary oxidant in RMs is singlet oxygen. G oxidation is enhanced in D2O and deuterated heptane and is diminished in the presence of sodium azide in RMs, also supporting 1O2 as the main G oxidant in RMs. Isotopic labeling experiments show that the oxygen atom in 8OG produced in RMs is not from water. The observed change in the G oxidation mechanism from a one-electron process in buffer to mostly 1O2 in RMs illustrates the importance of both DNA structure and DNA environment on the chemistry of G oxidation.

  14. Catalyst for carbon monoxide oxidation

    NASA Technical Reports Server (NTRS)

    Upchurch, Billy T. (Inventor); Miller, Irvin M. (Inventor); Brown, David R. (Inventor); Davis, Patricia (Inventor); Schryer, David R. (Inventor); Brown, Kenneth G. (Inventor); Vannorman, John D. (Inventor)

    1990-01-01

    A catalyst is disclosed for the combination of CO and O2 to form CO2, which includes a platinum group metal (e.g., platinum); a reducable metal oxide having multiple valence states (e.g., SnO2); and a compound which can bind water to its structure (e.g., silica gel). This catalyst is ideally suited for application to high-powered pulsed, CO2 lasers operating in a sealed or closed-cycle condition.

  15. Oxidation intermediates of α-glucosyl rutin by pulse radiolysis

    NASA Astrophysics Data System (ADS)

    Nakata, Kunihiko; Morita, Naofumi; Horii, Hideo; Chubachi, Mitsuo

    1997-11-01

    Transient intermediates generated in the reaction of α-glucosyl rutin (G-rutin) with the OH radical or the azide radical were investigated by pulse radiolysis. The OH radical reacted with G-rutin to produce the OH-adduct radical, followed by deprotonation in neutral and acidic solutions. In alkaline solutions, the OH-adduct di-anion radical formed from the di-anions of G-rutin were dehydrated to the phenoxyl radical. On the other hand, G-rutin was oxidized to one-electron oxidized cation radical by the azide radical. The pK a values of the OH radical adduct were found to be 6.83 ± 0.10 and 8.87 ± 0.13. While, the pK a values of the phenoxyl radical of G-rutin were found to be 7.52 ± 0.11 and 9.95 ± 0.13.

  16. Electrochemical oxidation of cyanide in the hydrocyclone cell

    SciTech Connect

    Dhamo, N.

    1996-12-31

    A diluted electroplating cyanide rinse water has been used to test the use of the hydrocyclone cell (HCC) in batch recycle mode of operation for the simultaneous oxidation of cyanide during the electrodeposition of silver. The results obtained in this work with regard to the final products, current efficiency and the number of transferred electrons per CN{sup {minus}} helped to establish a probable reaction scheme. According to this, the process occurs mainly with one-electron transfer, through cyanate and cyanogen as intermediate species. Meanwhile, under conditions where the electrolyte circulates in an open bath and flows successively through the cathodic and the anodic compartments, as in the case of the HCC system, the cyanate could be produced by the direct oxidation through air and/or generated peroxide and CN could be lost as HCN (g).

  17. Creating Multiple Processes from Multiple Intelligences.

    ERIC Educational Resources Information Center

    Wolffe, Robert; Robinson, Helja; Grant, Jean Marie

    1998-01-01

    Howard Gardner's multiple-intelligences theory stresses that all humans possess the various intelligences (linguistic, logical-mathematical, spatial, bodily-kinesthetic, musical, interpersonal, intrapersonal, and naturalist) to differing degrees, and most people can attain adequate competency levels. This article provides a sample checklist for…

  18. On Multiple Questions and Multiple WH Fronting.

    ERIC Educational Resources Information Center

    Rudin, Catherine

    An analysis of languages with multiple fronting of WH words (who, what, whom, etc.) looks in detail at Polish, Serbo-Croatian, Czech, Bulgarian (Slavic languages), and Romanian (a Romance language). In spite of their superficial similarity, the Slavic and East European languages that normally put all WH words at the beginning of clauses fall into…

  19. Oxidative stress and anti-oxidative mobilization in burn injury.

    PubMed

    Parihar, Arti; Parihar, Mordhwaj S; Milner, Stephen; Bhat, Satyanarayan

    2008-02-01

    A severe burn is associated with release of inflammatory mediators which ultimately cause local and distant pathophysiological effects. Mediators including Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) are increased in affected tissue, which are implicated in pathophysiological events observed in burn patients. The purpose of this article is to understand the role of oxidative stress in burns, in order to develop therapeutic strategies. All peer-reviewed, original and review articles published in the English language literature relevant to the topic of oxidative stress in burns in animals and human subjects were selected for this review and the possible roles of ROS and RNS in the pathophysiology of burns are discussed. Both increased xanthine oxidase and neutrophil activation appear to be the oxidant sources in burns. Free radicals have been found to have beneficial effects on antimicrobial action and wound healing. However following a burn, there is an enormous production of ROS which is harmful and implicated in inflammation, systemic inflammatory response syndrome, immunosuppression, infection and sepsis, tissue damage and multiple organ failure. Thus clinical response to burn is dependent on the balance between production of free radicals and its detoxification. Supplementation of antioxidants in human and animal models has proven benefit in decreasing distant organ failure suggesting a cause and effect relationship. We conclude that oxidative damage is one of the mechanisms responsible for the local and distant pathophysiological events observed after burn, and therefore anti-oxidant therapy might be beneficial in minimizing injury in burned patients.

  20. Multiple Instance Fuzzy Inference

    DTIC Science & Technology

    2015-12-02

    Zhang, Xin Chen, and Wei-Bang Chen, “An online multiple instance learn - ing system for semantic image retrieval,” in Multimedia Workshops, 2007. ISMW...INFERENCE A novel fuzzy learning framework that employs fuzzy inference to solve the problem of multiple instance learning (MIL) is presented. The...fuzzy learning framework that employs fuzzy inference to solve the problem of multiple instance learning (MIL) is presented. The framework introduces a

  1. Complications of multiple myeloma.

    PubMed

    Bladé, Joan; Rosiñol, Laura

    2007-12-01

    Multiple myeloma, also known as myeloma or plasma cell myeloma, is a progressive hematologic disease. Complications of multiple myeloma include renal insufficiency, hematologic complications (anemia, bone marrow failure, bleeding disorders), infections, bone complications (pathologic fractures, spinal cord compression, hyercalcemia), and neurologic complications (spinal cord and nerve root compression, intracranial plasmacytomas, leptomeningeal involvement, among others). This article reviews these various complications connected to multiple myeloma, examining their various causes and possible treatment.

  2. PREFACE: Semiconducting oxides Semiconducting oxides

    NASA Astrophysics Data System (ADS)

    Catlow, Richard; Walsh, Aron

    2011-08-01

    Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for

  3. Active neutron multiplicity analysis and Monte Carlo calculations

    NASA Astrophysics Data System (ADS)

    Krick, M. S.; Ensslin, N.; Langner, D. G.; Miller, M. C.; Siebelist, R.; Stewart, J. E.; Ceo, R. N.; May, P. K.; Collins, L. L., Jr.

    Active neutron multiplicity measurements of high-enrichment uranium metal and oxide samples have been made at Los Alamos and Y-12. The data from the measurements of standards at Los Alamos were analyzed to obtain values for neutron multiplication and source-sample coupling. These results are compared to equivalent results obtained from Monte Carlo calculations. An approximate relationship between coupling and multiplication is derived and used to correct doubles rates for multiplication and coupling. The utility of singles counting for uranium samples is also examined.

  4. Electrochemical oxidation of 243Am(III) in nitric acid by a terpyridyl-derivatized electrode

    SciTech Connect

    Dares, C. J.; Lapides, A. M.; Mincher, B. J.; Meyer, T. J.

    2015-11-05

    A high surface area, tin-doped indium oxide electrode surface-derivatized with a terpyridine ligand has been applied to the oxidation of trivalent americium to Am(V) and Am(VI) in nitric acid. Potentials as low as 1.8 V vs. the saturated calomel electrode are used, 0.7 V lower than the 2.6 V potential for one-electron oxidation of Am(III) to Am(IV) in 1 M acid. This simple electrochemical procedure provides, for the first time, a method for accessing the higher oxidation states of Am in non-complexing media for developing the coordination chemistries of Am(V) and Am(VI) and, more importantly, for separation of americium from nuclear waste streams.

  5. Nitric oxide and cancer

    PubMed Central

    Muntané, Jordi; la Mata, Manuel De

    2010-01-01

    Nitric oxide (NO) is a lipophilic, highly diffusible and short-lived physiological messenger which regulates a variety of important physiological responses including vasodilation, respiration, cell migration, immune response and apoptosis. NO is synthesized by three differentially gene-encoded NO synthase (NOS) in mammals: neuronal NOS (nNOS or NOS-1), inducible NOS (iNOS or NOS-2) and endothelial NOS (eNOS or NOS-3). All isoforms of NOS catalyze the reaction of L-arginine, NADPH and oxygen to NO, L-citrulline and NADP. NO may exert its cellular action by cGMP-dependent as well as by cGMP-independent pathways including postranslational modifications in cysteine (S-nitrosylation or S-nitrosation) and tyrosine (nitration) residues, mixed disulfide formation (S-nitrosoglutathione or GSNO) or promoting further oxidation protein stages which have been related to altered protein function and gene transcription, genotoxic lesions, alteration of cell-cycle check points, apoptosis and DNA repair. NO sensitizes tumor cells to chemotherapeutic compounds. The expression of NOS-2 and NOS-3 has been found to be increased in a variety of human cancers. The multiple actions of NO in the tumor environment is related to heterogeneous cell responses with particular attention in the regulation of the stress response mediated by the hypoxia inducible factor-1 and p53 generally leading to growth arrest, apoptosis or adaptation. PMID:21161018

  6. On the consistent definition of spin-orbit effects calculated by relativistic effective core potentials with one-electron spin-orbit operators: Comparison of spin-orbit effects for Tl, TlH, TlH3, PbH2, and PbH4

    NASA Astrophysics Data System (ADS)

    Han, Young-Kyu; Bae, Cheolbeom; Lee, Yoon Sup

    1999-05-01

    The spin-orbit effects for Tl, TlH, TlH3, PbH2, and PbH4 are evaluated by two-component calculations using several relativistic effective core potentials (RECP) with one-electron spin-orbit operators. The used RECPs are shape-consistent RECPs derived by Wildman et al. [J. Chem. Phys. 107, 9975 (1997)] and three sets of energy-consistent (or adjusted) RECPs published by Schwerdtfeger et al. [Phys. Scr. 36, 453 (1987); J. Chem. Phys. 90, 762 (1989)], Küchle et al. [Mol. Phys. 74, 1245 (1991)], and Leininger et al. [Chem. Phys. 217, 19 (1997)]. The shape-consistent RECP results are in very good agreement with the Küchle et al. energy-consistent RECP results for all the molecules studied here and all-electron results for TlH. The RECPs of Schwerdtfeger et al. and Leininger et al. seem to provide qualitatively different spin-orbit effects. If one defines spin-free RECP as the potential average of the corresponding two-component RECP, all RECPs give very similar spin-orbit effects for all the cases. Most of the discrepancies of molecular spin-orbit effects among various RECPs reported in the literature may originate from different definitions of RECPs with or without a spin-orbit term and not from the inherent difference in spin-orbit operators.

  7. Lipid oxidation and improving the oxidative stability.

    PubMed

    Shahidi, Fereidoon; Zhong, Ying

    2010-11-01

    Lipids are a major component of food and important structural and functional constituents of cells in biological systems. However, this diverse group of substances is prone to oxidation through various pathways. Their oxidative stability depends on a number of intrinsic and extrinsic factors, including the unsaturation of their fatty acids, composition of minor components, environment conditions, delivery techniques and use of antioxidants, among others. Lipid oxidation has detrimental effects on both food quality and human health, and efforts must be made to minimize oxidation and improve oxidative stability of lipid products. Antioxidant strategy has been successfully employed in the food industry for quality preservation of the food products and in the medicinal industry for risk reduction of numerous oxidative stress-mediated diseases. This tutorial review will provide important knowledge about lipid oxidation, including the mechanism and factors involved in oxidation, as well as strategies for improving oxidative stability of lipids.

  8. Sequential multiple analyses of atmospheric nitrous acid and nitrogen oxides.

    PubMed

    Toda, Kei; Hato, Yuki; Mori, Kotaro; Ohira, Shin-Ichi; Namihira, Takao

    2007-03-15

    Sequential injection analysis (SIA) was applied to multi-gas monitoring for atmospheric analysis. HONO, NO(2) or NO was collected in an individual diffusion scrubber in which the channel array was filled with either HCl or triethanolamine solution. All analytes were collected in the form of nitrite ions in the scrubber, and were transferred via a 12-port selection valve into a 2.5-ml syringe. The reagent, 3-amino-1,5-naphthalenedisulfonic acid (C-acid) solution was subsequently introduced into the syringe, and inter-mixed with the nitrite sample, whereafter the mixed solution was transferred to a heated reactor and held for 3min at 100 degrees C. After that, the sample/reagent solution was returned to the syringe and alkalinized. Then, the final solution was analyzed using a homemade fluorescence detector. Atmospheric HONO, NO(2) and NO were successfully monitored 3 or 4times/h. The limits of detection were 0.22, 0.28 and 0.35ppbv for HONO, NO(2) and NO, respectively. It was demonstrated for the first time that SIA is a good tool for multi-gas atmospheric analysis. These nitrogen-oxygen compounds are interconvertible, and the simultaneous measurement of these gases is important. Especially, HONO is a source of OH radicals which contribute greatly to atmospheric pollution, and indeed atmospheric chemistry. This method allows the three gases to be measured using one system. The NO(2) and NO data obtained by SIA was compared with those obtained using chemiluminescence instrument. SIA has been successfully applied to atmospheric measurements. Interestingly, it was observed that HONO levels rose toward the end of periods of rain.

  9. Pathways of peroxynitrite oxidation of thiol groups.

    PubMed

    Quijano, C; Alvarez, B; Gatti, R M; Augusto, O; Radi, R

    1997-02-15

    Peroxynitrite mediates the oxidation of the thiol group of both cysteine and glutathione. This process is associated with oxygen consumption. At acidic pH and a cysteine/peroxynitrite molar ratio of < or = 1.2, there was a single fast phase of oxygen consumption, which increased with increasing concentrations of both cysteine and oxygen. At higher molar ratios the profile of oxygen consumption became biphasic, with a fast phase (phase I) that decreased with increasing cysteine concentration, followed by a slow phase (phase II) whose rate of oxygen consumption increased with increasing cysteine concentration. Oxygen consumption in phase I was inhibited by desferrioxamine and 5,5-dimethyl-1-pyrroline N-oxide, but not by mannitol; superoxide dismutase also inhibited oxygen consumption in phase I, while catalase added during phase II decreased the rate of oxygen consumption. For both cysteine and glutathione, oxygen consumption in phase I was maximal at neutral to acidic pH: in contrast, total thiol oxidation was maximal at alkaline pH. EPR spin-trapping studies using N-tert-butyl-alpha-phenylnitrone indicated that the yield of thiyl radical adducts had a pH profile comparable with that found for oxygen consumption. The apparent second-order rate constants for the reactions of peroxynitrite with cysteine and glutathione were 1290 +/- 30 M-1.S-1 and 281 +/- 6 M-1.S-1 respectively at pH 5.75 and 37 degrees C. These results are consistent with two different pathways participating in the reaction of peroxynitrite with low-molecular-mass thiols: (a) the reaction of the peroxynitrite anion with the protonated thiol group, in a second-order process likely to involve a two-electron oxidation, and (b) the reaction of peroxynitrous acid, or a secondary species derived from it, with the thiolate in a one-electron transfer process that yields thiyl radicals capable of initiating an oxygen-dependent radical chain reaction.

  10. Pathways of peroxynitrite oxidation of thiol groups.

    PubMed Central

    Quijano, C; Alvarez, B; Gatti, R M; Augusto, O; Radi, R

    1997-01-01

    Peroxynitrite mediates the oxidation of the thiol group of both cysteine and glutathione. This process is associated with oxygen consumption. At acidic pH and a cysteine/peroxynitrite molar ratio of < or = 1.2, there was a single fast phase of oxygen consumption, which increased with increasing concentrations of both cysteine and oxygen. At higher molar ratios the profile of oxygen consumption became biphasic, with a fast phase (phase I) that decreased with increasing cysteine concentration, followed by a slow phase (phase II) whose rate of oxygen consumption increased with increasing cysteine concentration. Oxygen consumption in phase I was inhibited by desferrioxamine and 5,5-dimethyl-1-pyrroline N-oxide, but not by mannitol; superoxide dismutase also inhibited oxygen consumption in phase I, while catalase added during phase II decreased the rate of oxygen consumption. For both cysteine and glutathione, oxygen consumption in phase I was maximal at neutral to acidic pH: in contrast, total thiol oxidation was maximal at alkaline pH. EPR spin-trapping studies using N-tert-butyl-alpha-phenylnitrone indicated that the yield of thiyl radical adducts had a pH profile comparable with that found for oxygen consumption. The apparent second-order rate constants for the reactions of peroxynitrite with cysteine and glutathione were 1290 +/- 30 M-1.S-1 and 281 +/- 6 M-1.S-1 respectively at pH 5.75 and 37 degrees C. These results are consistent with two different pathways participating in the reaction of peroxynitrite with low-molecular-mass thiols: (a) the reaction of the peroxynitrite anion with the protonated thiol group, in a second-order process likely to involve a two-electron oxidation, and (b) the reaction of peroxynitrous acid, or a secondary species derived from it, with the thiolate in a one-electron transfer process that yields thiyl radicals capable of initiating an oxygen-dependent radical chain reaction. PMID:9078258

  11. Orchestrating Multiple Intelligences

    ERIC Educational Resources Information Center

    Moran, Seana; Kornhaber, Mindy; Gardner, Howard

    2006-01-01

    Education policymakers often go astray when they attempt to integrate multiple intelligences theory into schools, according to the originator of the theory, Howard Gardner, and his colleagues. The greatest potential of a multiple intelligences approach to education grows from the concept of a profile of intelligences. Each learner's intelligence…

  12. Applying Multiple Intelligences

    ERIC Educational Resources Information Center

    Christodoulou, Joanna A.

    2009-01-01

    The ideas of multiple intelligences introduced by Howard Gardner of Harvard University more than 25 years ago have taken form in many ways, both in schools and in other sometimes-surprising settings. The silver anniversary of Gardner's learning theory provides an opportunity to reflect on the ways multiple intelligences theory has taken form and…

  13. Orchestrating Multiple Intelligences

    ERIC Educational Resources Information Center

    Moran, Seana; Kornhaber, Mindy; Gardner, Howard

    2006-01-01

    Education policymakers often go astray when they attempt to integrate multiple intelligences theory into schools, according to the originator of the theory, Howard Gardner, and his colleagues. The greatest potential of a multiple intelligences approach to education grows from the concept of a profile of intelligences. Each learner's intelligence…

  14. Constraining Multiple Grammars

    ERIC Educational Resources Information Center

    Hopp, Holger

    2014-01-01

    This article offers the author's commentary on the Multiple Grammars (MG) language acquisition theory proposed by Luiz Amaral and Tom Roeper in the present issue. Multiple Grammars advances the claim that optionality is a constitutive characteristic of any one grammar, with interlanguage grammars being perhaps the clearest examples of a…

  15. Multiple density layered insulator

    DOEpatents

    Alger, T.W.

    1994-09-06

    A multiple density layered insulator for use with a laser is disclosed which provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation. 4 figs.

  16. Multiple density layered insulator

    DOEpatents

    Alger, Terry W.

    1994-01-01

    A multiple density layered insulator for use with a laser is disclosed wh provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation.

  17. Applying Multiple Intelligences

    ERIC Educational Resources Information Center

    Christodoulou, Joanna A.

    2009-01-01

    The ideas of multiple intelligences introduced by Howard Gardner of Harvard University more than 25 years ago have taken form in many ways, both in schools and in other sometimes-surprising settings. The silver anniversary of Gardner's learning theory provides an opportunity to reflect on the ways multiple intelligences theory has taken form and…

  18. Lethal multiple pterygium syndrome

    PubMed Central

    Joshi, Tulika; Noor, Nazia Nagori; Kural, Moolraj; Tripathi, Amita

    2016-01-01

    The multiple pterygium syndrome is consist of wide range of fetal malformations which have a genetic linkage. A defect in embryonic acetylcholine receptor which can be inherited as autosomal recessive, autosomal dominant, or X-linked fashion is the cause of this syndrome. We present a sporadic case of lethal multiple pterygium syndrome. PMID:27843868

  19. Assessing Children's Multiplicative Thinking

    ERIC Educational Resources Information Center

    Hurst, Chris; Hurrell, Derek

    2016-01-01

    Multiplicative thinking is a "big idea" of mathematics that underpins much of the mathematics learned beyond the early primary school years. This paper reports on a current study that utilises an interview tool and a written quiz to gather data about children's multiplicative thinking. The development of the tools and some of the…

  20. Constraining Multiple Grammars

    ERIC Educational Resources Information Center

    Hopp, Holger

    2014-01-01

    This article offers the author's commentary on the Multiple Grammars (MG) language acquisition theory proposed by Luiz Amaral and Tom Roeper in the present issue. Multiple Grammars advances the claim that optionality is a constitutive characteristic of any one grammar, with interlanguage grammars being perhaps the clearest examples of a…

  1. Mechanism of oxidative conversion of Amplex® Red to resorufin: Pulse radiolysis and enzymatic studies.

    PubMed

    Dębski, Dawid; Smulik, Renata; Zielonka, Jacek; Michałowski, Bartosz; Jakubowska, Małgorzata; Dębowska, Karolina; Adamus, Jan; Marcinek, Andrzej; Kalyanaraman, Balaraman; Sikora, Adam

    2016-06-01

    Amplex® Red (10-acetyl-3,7-dihydroxyphenoxazine) is a fluorogenic probe widely used to detect and quantify hydrogen peroxide in biological systems. Detection of hydrogen peroxide is based on peroxidase-catalyzed oxidation of Amplex® Red to resorufin. In this study we investigated the mechanism of one-electron oxidation of Amplex® Red and we present the spectroscopic characterization of transient species formed upon the oxidation. Oxidation process has been studied by a pulse radiolysis technique with one-electron oxidants (N3(•), CO3(•-),(•)NO2 and GS(•)). The rate constants for the Amplex® Red oxidation by N3(•) ((2)k=2.1·10(9)M(-1)s(-1), at pH=7.2) and CO3(•-) ((2)k=7.6·10(8)M(-1)s(-1), at pH=10.3) were determined. Two intermediates formed during the conversion of Amplex® Red into resorufin have been characterized. Based on the results obtained, the mechanism of transformation of Amplex® Red into resorufin, involving disproportionation of the Amplex® Red-derived radical species, has been proposed. The results indicate that peroxynitrite-derived radicals, but not peroxynitrite itself, are capable to oxidize Amplex® Red to resorufin. We also demonstrate that horseradish peroxidase can catalyze oxidation of Amplex® Red not only by hydrogen peroxide, but also by peroxynitrite, which needs to be considered when employing the probe for hydrogen peroxide detection. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Multiple scattering technique lidar

    NASA Technical Reports Server (NTRS)

    Bissonnette, Luc R.

    1992-01-01

    The Bernouilli-Ricatti equation is based on the single scattering description of the lidar backscatter return. In practice, especially in low visibility conditions, the effects of multiple scattering can be significant. Instead of considering these multiple scattering effects as a nuisance, we propose here to use them to help resolve the problems of having to assume a backscatter-to-extinction relation and specifying a boundary value for a position far remote from the lidar station. To this end, we have built a four-field-of-view lidar receiver to measure the multiple scattering contributions. The system has been described in a number of publications that also discuss preliminary results illustrating the multiple scattering effects for various environmental conditions. Reported here are recent advances made in the development of a method of inverting the multiple scattering data for the determination of the aerosol scattering coefficient.

  3. Oxide surfaces.

    PubMed

    Willmott, Phil

    2008-07-02

    Although the history of metal oxides and their surfaces goes back several decades to landmark studies, such as Mott and Peierls' explanation of electrical insulation in materials that are predicted in band theory to be conducting, or the observation by Morin of the superfast metal-to-insulator transition in vanadium dioxide, it is only in the last two decades that the world of condensed matter physics has become increasingly dominated by research into complex metal oxides. This has been driven most notably by an attempt to better understand and describe the fundamental physical processes behind their seemingly endless spectrum of properties, which in turn has also led to the discovery of novel phenomena, most prominently demonstrated by the discovery of high-temperature superconductivity in 1986, colossal magnetoresistance in 1994, and most recently, the formation of a two-dimensional conducting layer at the interface between two band insulators in 2004. One important reason why metal oxides, particularly in the form of thin films, have become such a popular subject for basic condensed matter research is that they offer a uniquely versatile materials base for the development of novel technologies. They owe this versatility both to the many different elemental combinations that lead to structurally similar forms, and also to the fact that in many cases, the strong interaction between the valence electrons means that there is a subtle interplay between structure and magnetic and electronic properties. This aspect has led in recent years to the birth or renaissance of research fields such as spintronics, orbital ordering, and multiferroics. Surfaces and interfaces are especially interesting in these strongly-correlated electron systems, where the rearrangement of electrical charge resulting from a minimization of surface or interfacial energy can have unexpected and often exciting consequences. Indeed, as the drive to miniaturize devices well below the micron size

  4. UO2 oxidative corrosion by non-classical diffusion

    SciTech Connect

    Stubbs, Joanne; Chaka, Anne M.; Ilton, Eugene S.; Biwer, Craig A.; Engelhard, Mark H.; Bargar, John R.; Eng, Peter

    2015-06-01

    Using x-ray scattering, spectroscopy, and computational methods, we show that oxidation of the UO2 (111) surface results in a self-organized arrangement of oxygen interstitials with three-layer periodicity, producing a nanoscale oscillatory oxidation front with uranium in three oxidation states: IV, V, and VI. This complex diffusion profile is driven by the transfer of the lowest energy U5f electrons from multiple U atoms into the O2p band. Our results contrast with all previous bulk structural oxidation models and the simple exponential oxidation front expected from classical diffusion.

  5. ZnO-based multiple channel and multiple gate FinMOSFETs

    NASA Astrophysics Data System (ADS)

    Lee, Ching-Ting; Huang, Hung-Lin; Tseng, Chun-Yen; Lee, Hsin-Ying

    2016-02-01

    In recent years, zinc oxide (ZnO)-based metal-oxide-semiconductor field-effect transistors (MOSFETs) have attracted much attention, because ZnO-based semiconductors possess several advantages, including large exciton binding energy, nontoxicity, biocompatibility, low material cost, and wide direct bandgap. Moreover, the ZnO-based MOSFET is one of most potential devices, due to the applications in microwave power amplifiers, logic circuits, large scale integrated circuits, and logic swing. In this study, to enhance the performances of the ZnO-based MOSFETs, the ZnObased multiple channel and multiple gate structured FinMOSFETs were fabricated using the simple laser interference photolithography method and the self-aligned photolithography method. The multiple channel structure possessed the additional sidewall depletion width control ability to improve the channel controllability, because the multiple channel sidewall portions were surrounded by the gate electrode. Furthermore, the multiple gate structure had a shorter distance between source and gate and a shorter gate length between two gates to enhance the gate operating performances. Besides, the shorter distance between source and gate could enhance the electron velocity in the channel fin structure of the multiple gate structure. In this work, ninety one channels and four gates were used in the FinMOSFETs. Consequently, the drain-source saturation current (IDSS) and maximum transconductance (gm) of the ZnO-based multiple channel and multiple gate structured FinFETs operated at a drain-source voltage (VDS) of 10 V and a gate-source voltage (VGS) of 0 V were respectively improved from 11.5 mA/mm to 13.7 mA/mm and from 4.1 mS/mm to 6.9 mS/mm in comparison with that of the conventional ZnO-based single channel and single gate MOSFETs.

  6. Ferricytochrome (c) directly oxidizes aminoacetone to methylglyoxal, a catabolite accumulated in carbonyl stress.

    PubMed

    Sartori, Adriano; Mano, Camila M; Mantovani, Mariana C; Dyszy, Fábio H; Massari, Júlio; Tokikawa, Rita; Nascimento, Otaciro R; Nantes, Iseli L; Bechara, Etelvino J H

    2013-01-01

    Age-related diseases are associated with increased production of reactive oxygen and carbonyl species such as methylglyoxal. Aminoacetone, a putative threonine catabolite, is reportedly known to undergo metal-catalyzed oxidation to methylglyoxal, NH4(+) ion, and H2O2 coupled with (i) permeabilization of rat liver mitochondria, and (ii) apoptosis of insulin-producing cells. Oxidation of aminoacetone to methylglyoxal is now shown to be accelerated by ferricytochrome c, a reaction initiated by one-electron reduction of ferricytochrome c by aminoacetone without amino acid modifications. The participation of O2(•-) and HO (•) radical intermediates is demonstrated by the inhibitory effect of added superoxide dismutase and Electron Paramagnetic Resonance spin-trapping experiments with 5,5'-dimethyl-1-pyrroline-N-oxide. We hypothesize that two consecutive one-electron transfers from aminoacetone (E0 values = -0.51 and -1.0 V) to ferricytochrome c (E0 = 0.26 V) may lead to aminoacetone enoyl radical and, subsequently, imine aminoacetone, whose hydrolysis yields methylglyoxal and NH4(+) ion. In the presence of oxygen, aminoacetone enoyl and O2(•-) radicals propagate aminoacetone oxidation to methylglyoxal and H2O2. These data endorse the hypothesis that aminoacetone, putatively accumulated in diabetes, may directly reduce ferricyt c yielding methylglyoxal and free radicals, thereby triggering redox imbalance and adverse mitochondrial responses.

  7. Ferricytochrome c Directly Oxidizes Aminoacetone to Methylglyoxal, a Catabolite Accumulated in Carbonyl Stress

    PubMed Central

    Sartori, Adriano; Mano, Camila M.; Mantovani, Mariana C.; Dyszy, Fábio H.; Massari, Júlio; Tokikawa, Rita; Nascimento, Otaciro R.; Nantes, Iseli L.; Bechara, Etelvino J. H.

    2013-01-01

    Age-related diseases are associated with increased production of reactive oxygen and carbonyl species such as methylglyoxal. Aminoacetone, a putative threonine catabolite, is reportedly known to undergo metal-catalyzed oxidation to methylglyoxal, NH4+ ion, and H2O2 coupled with (i) permeabilization of rat liver mitochondria, and (ii) apoptosis of insulin-producing cells. Oxidation of aminoacetone to methylglyoxal is now shown to be accelerated by ferricytochrome c, a reaction initiated by one-electron reduction of ferricytochrome c by aminoacetone without amino acid modifications. The participation of O2•− and HO• radical intermediates is demonstrated by the inhibitory effect of added superoxide dismutase and Electron Paramagnetic Resonance spin-trapping experiments with 5,5′-dimethyl-1-pyrroline-N-oxide. We hypothesize that two consecutive one-electron transfers from aminoacetone (E0 values = −0.51 and −1.0 V) to ferricytochrome c (E0 = 0.26 V) may lead to aminoacetone enoyl radical and, subsequently, imine aminoacetone, whose hydrolysis yields methylglyoxal and NH4+ ion. In the presence of oxygen, aminoacetone enoyl and O2•− radicals propagate aminoacetone oxidation to methylglyoxal and H2O2. These data endorse the hypothesis that aminoacetone, putatively accumulated in diabetes, may directly reduce ferricyt c yielding methylglyoxal and free radicals, thereby triggering redox imbalance and adverse mitochondrial responses. PMID:23483930

  8. Multiple frame cluster tracking

    NASA Astrophysics Data System (ADS)

    Gadaleta, Sabino; Klusman, Mike; Poore, Aubrey; Slocumb, Benjamin J.

    2002-08-01

    Tracking large number of closely spaced objects is a challenging problem for any tracking system. In missile defense systems, countermeasures in the form of debris, chaff, spent fuel, and balloons can overwhelm tracking systems that track only individual objects. Thus, tracking these groups or clusters of objects followed by transitions to individual object tracking (if and when individual objects separate from the groups) is a necessary capability for a robust and real-time tracking system. The objectives of this paper are to describe the group tracking problem in the context of multiple frame target tracking and to formulate a general assignment problem for the multiple frame cluster/group tracking problem. The proposed approach forms multiple clustering hypotheses on each frame of data and base individual frame clustering decisions on the information from multiple frames of data in much the same way that MFA or MHT work for individual object tracking. The formulation of the assignment problem for resolved object tracking and candidate clustering methods for use in multiple frame cluster tracking are briefly reviewed. Then, three different formulations are presented for the combination of multiple clustering hypotheses on each frame of data and the multiple frame assignments of clusters between frames.

  9. Carbohydrate and exercise performance: the role of multiple transportable carbohydrates.

    PubMed

    Jeukendrup, Asker E

    2010-07-01

    Carbohydrate feeding has been shown to be ergogenic, but recently substantial advances have been made in optimizing the guidelines for carbohydrate intake during prolonged exercise. It was found that limitations to carbohydrate oxidation were in the absorptive process most likely because of a saturation of carbohydrate transporters. By using a combination of carbohydrates that use different intestinal transporters for absorption it was shown that carbohydrate delivery and oxidation could be increased. Studies demonstrated increases in exogenous carbohydrate oxidation rates of up to 65% of glucose: fructose compared with glucose only. Exogenous carbohydrate oxidation rates reach values of 1.75 g/min whereas previously it was thought that 1 g/min was the absolute maximum. The increased carbohydrate oxidation with multiple transportable carbohydrates was accompanied by increased fluid delivery and improved oxidation efficiency, and thus the likelihood of gastrointestinal distress may be diminished. Studies also demonstrated reduced fatigue and improved exercise performance with multiple transportable carbohydrates compared with a single carbohydrate. Multiple transportable carbohydrates, ingested at high rates, can be beneficial during endurance sports in which the duration of exercise is 3 h or more.

  10. Fatty Acid Oxidation Disorders

    MedlinePlus

    ... other health conditions > Fatty acid oxidation disorders Fatty acid oxidation disorders E-mail to a friend Please ... these disorders, go to genetests.org . What fatty acid oxidation disorders are tested for in newborn screening? ...

  11. [Multiple sclerosis and migration].

    PubMed

    Materljan, E; Sepcić, J; Materljan, B

    1996-01-01

    Multiple sclerosis, original primary demyelination in the central nervous system, is a disease of as yet unknown cause. Epidemiologic research may contribute to the clarification of this problem. Migration studies have proven that susceptibility to multiple sclerosis is associated with ethnic origin and environment, and that the critical age for the disease development is till 15 years. In Croatia, emigrating inhabitants of Gorski Kotar, a region with high exposure to this disease, carry the risk of multiple sclerosis development, provided that have emigrated after adolescence.

  12. Multiple Myeloma and Diabetes

    PubMed Central

    Issa, Zeinab A.; Zantout, Mira S.; Azar, Sami T.

    2011-01-01

    Multiple myeloma is a malignant plasma cell disorder that accounts for approximately 10% of all hematologic cancers. It is characterized by accumulation of clonal plasma cells, predominantly in the bone marrow. The prevalence of type 2 diabetes is increasing; therefore, it is expected that there will be an increase in the diagnosis of multiple myeloma with concomitant diabetes mellitus. The treatment of multiple myeloma and diabetes mellitus is multifaceted. The coexistence of the two conditions in a patient forms a major challenge for physicians. PMID:22363889

  13. Multiple intracranial enterogenous cysts.

    PubMed Central

    Walls, T J; Purohit, D P; Aji, W S; Schofield, I S; Barwick, D D

    1986-01-01

    The case of a 40-year-old woman with increasing ataxia is described. Although the clinical presentation and evoked response studies raised the possibility of multiple sclerosis, further investigation revealed multiple cystic intracranial lesions. Surgical excision of one of the lesions relieved the patient's symptoms. Histological examination revealed that this was an enterogenous cyst. Although single cysts of this type have rarely been reported occurring in the posterior cranial fossa, the occurrence of multiple lesions, some in the supratentorial compartment, appears to be unique. Images PMID:3701354

  14. Vision and multiple sclerosis.

    PubMed

    Hickman, Simon J; Raoof, Naz; McLean, Rebecca J; Gottlob, Irene

    2014-01-01

    Multiple sclerosis can affect vision in many ways, including optic neuritis, chronic optic neuropathy, retrochiasmal visual field defects, higher order cortical processing, double vision, nystagmus and also by related ocular conditions such as uveitis. There are also side effects from recently introduced multiple sclerosis treatments that can affect vision. This review will discuss all these aspects and how they come together to cause visual symptoms. It will then focus on practical aspects of how to recognise when there is a vision problem in a multiple sclerosis patient and on what treatments are available to improve vision.

  15. Single-electron reduction of the oxidized state is coupled to proton uptake via the K pathway in Paracoccus denitrificans cytochrome c oxidase

    PubMed Central

    Ruitenberg, Maarten; Kannt, Aimo; Bamberg, Ernst; Ludwig, Bernd; Michel, Hartmut; Fendler, Klaus

    2000-01-01

    The reductive part of the catalytic cycle of cytochrome c oxidase from Paracoccus denitrificans was examined by using time-resolved potential measurements on black lipid membranes. Proteoliposomes were adsorbed to the black lipid membranes and RuII(2,2′-bipyridyl)32+ was used as photoreductant to measure flash-induced membrane potential generation. Single-electron reduction of the oxidized wild-type cytochrome c oxidase reveals two phases of membrane potential generation (τ1 ≈ 20 μs and τ2 ≈ 175 μs) at pH 7.4. The fast phase is not sensitive to cyanide and is assigned to electron transfer from CuA to heme a. The slower phase is inhibited completely by cyanide and shows a kinetic deuterium isotope effect by a factor of 2–3. Although two enzyme variants mutated in the so-called D pathway of proton transfer (D124N and E278Q) show the same time constants and relative amplitudes as the wild-type enzyme, in the K pathway variant K354M, τ2 is increased to 900 μs. This result suggests uptake of a proton through the K pathway during the transition from the oxidized to the one-electron reduced state. After the second laser flash under anaerobic conditions, a third electrogenic phase with a time constant of ≈1 ms appears. The amplitude of this phase grows with increasing flash number. We explain this growth by injection of a second electron into the single-electron reduced enzyme. On multiple flashes, both D pathway mutants behave differently compared with the wild type and two additional slow phases of τ3 ≈ 2 ms and τ4 ≈ 15 ms are observed. These results suggest that the D pathway is involved in proton transfer coupled to the uptake of the second electron. PMID:10781069

  16. Neutron multiplicity assay of impure materials using four different neutron counters

    SciTech Connect

    Stewart, J.E. Krick, M.S.; Langner, D.G.; Wenz, T.R.

    1998-12-01

    During an advanced IAEA inspector training course given at Los Alamos in November, 1997, the opportunity existed for an intercomparison study of various neutron detectors to quantify measurement performance using pure and impure plutonium oxide and mixed uranium-plutonium oxide (MOX) items. Because of the cost of counters designed specifically for multiplicity analysis, it was desired to explore the limits of other, less costly and less efficient detectors. This paper presents and intercompares neutron coincidence and multiplicity assay performance for five detectors, which vary widely in detection efficiency. Eight pure plutonium oxide and twelve impure plutonium oxide and MOX working standards were used in the study.

  17. Pomalidomide for Multiple Myeloma

    Cancer.gov

    A summary of results from a phase III trial that compared the combination of pomalidomide (Pomalyst®) and low-dose dexamethasone versus high-dose dexamethasone alone in patients with multiple myeloma that has progressed despite other treatments.

  18. Multiple shell fusion targets

    DOEpatents

    Lindl, J.D.; Bangerter, R.O.

    1975-10-31

    Multiple shell fusion targets for use with electron beam and ion beam implosion systems are described. The multiple shell targets are of the low-power type and use a separate relatively low Z, low density ablator at large radius for the outer shell, which reduces the focusing and power requirements of the implosion system while maintaining reasonable aspect ratios. The targets use a high Z, high density pusher shell placed at a much smaller radius in order to obtain an aspect ratio small enough to protect against fluid instability. Velocity multiplication between these shells further lowers the power requirements. Careful tuning of the power profile and intershell density results in a low entropy implosion which allows breakeven at low powers. For example, with ion beams as a power source, breakeven at 10-20 Terrawatts with 10 MeV alpha particles for imploding a multiple shell target can be accomplished.

  19. Taking multiple medicines safely

    MedlinePlus

    ... medlineplus.gov/ency/patientinstructions/000883.htm Taking multiple medicines safely To use the sharing features on this ... directed. Why You May Need More Than One Medicine You may take more than one medicine to ...

  20. The Multiplicative Situation

    ERIC Educational Resources Information Center

    Hurst, Chris

    2015-01-01

    The relationships between three critical elements, and the associated mathematical language, to assist students to make the critical transition from additive to multiplicative thinking are examined in this article by Chris Hurst.

  1. Sexual Health - Multiple Languages

    MedlinePlus

    ... Map FAQs Customer Support Health Topics Drugs & Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Sexual Health URL of this page: https://medlineplus.gov/ ...

  2. The Multiplicative Situation

    ERIC Educational Resources Information Center

    Hurst, Chris

    2015-01-01

    The relationships between three critical elements, and the associated mathematical language, to assist students to make the critical transition from additive to multiplicative thinking are examined in this article by Chris Hurst.

  3. Cholesterol - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Cholesterol URL of this page: https://medlineplus.gov/languages/cholesterol.html Other topics A-Z Expand Section ...

  4. Concussion - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Concussion URL of this page: https://medlineplus.gov/languages/concussion.html Other topics A-Z Expand Section ...

  5. Dentures - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Dentures URL of this page: https://medlineplus.gov/languages/dentures.html Other topics A-Z Expand Section ...

  6. Crohn's Disease - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Crohn's Disease URL of this page: https://medlineplus.gov/languages/crohnsdisease.html Other topics A-Z Expand Section ...

  7. Colonic Diseases - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Colonic Diseases URL of this page: https://medlineplus.gov/languages/colonicdiseases.html Other topics A-Z Expand Section ...

  8. Multiple System Atrophy (MSA)

    MedlinePlus

    ... to-day activities Vocal cord paralysis, which makes speech and breathing difficult Increased difficulty swallowing People typically live about seven to 10 years after multiple system atrophy symptoms first appear. However, the ...

  9. Understanding Multiplication of Fractions.

    ERIC Educational Resources Information Center

    Sweetland, Robert D.

    1984-01-01

    Discussed the use of Cuisenaire rods in teaching the multiplication of fractions. Considers whole number times proper fraction, proper fraction multiplied by proper fraction, mixed number times proper fraction, and mixed fraction multiplied by mixed fractions. (JN)

  10. Breast Diseases - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Breast Diseases URL of this page: https://medlineplus.gov/languages/breastdiseases.html Other topics A-Z Expand Section ...

  11. Anemia - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Anemia URL of this page: https://medlineplus.gov/languages/anemia.html Other topics A-Z Expand Section ...

  12. Anxiety - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Anxiety URL of this page: https://medlineplus.gov/languages/anxiety.html Other topics A-Z Expand Section ...

  13. Anal Disorders - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Anal Disorders URL of this page: https://medlineplus.gov/languages/analdisorders.html Other topics A-Z Expand Section ...

  14. Animal Bites - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Animal Bites URL of this page: https://medlineplus.gov/languages/animalbites.html Other topics A-Z Expand Section ...

  15. Alzheimer's Disease - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Alzheimer's Disease URL of this page: https://medlineplus.gov/languages/alzheimersdisease.html Other topics A-Z Expand Section ...

  16. Bladder Diseases - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Bladder Diseases URL of this page: https://medlineplus.gov/languages/bladderdiseases.html Other topics A-Z Expand Section ...

  17. Burns - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Burns URL of this page: https://medlineplus.gov/languages/burns.html Other topics A-Z Expand Section ...

  18. Breathing Problems - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Breathing Problems URL of this page: https://medlineplus.gov/languages/breathingproblems.html Other topics A-Z Expand Section ...

  19. Childbirth - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Childbirth URL of this page: https://medlineplus.gov/languages/childbirth.html Other topics A-Z Expand Section ...

  20. Acute Bronchitis - Multiple Languages

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Acute Bronchitis URL of this page: https://medlineplus.gov/languages/acutebronchitis.html Other topics A-Z Expand Section ...