Cooperative Effects Between Arginine and Glutamic Acid in the Amino Acid-Catalyzed Aldol Reaction.

PubMed

Valero, Guillem; Moyano, Albert

2016-08-01

Catalysis of the aldol reaction between cyclohexanone and 4-nitrobenzaldehyde by mixtures of L-Arg and of L-Glu in wet dimethyl sulfoxide (DMSO) takes place with higher enantioselectivity (up to a 7-fold enhancement in the anti-aldol for the 1:1 mixture) than that observed when either L-Glu or L-Arg alone are used as the catalysts. These results can be explained by the formation of a catalytically active hydrogen-bonded complex between both amino acids, and demonstrate the possibility of positive cooperative effects in catalysis by two different α-amino acids. Chirality 28:599-605, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Organics Characterization Of DWPF Alternative Reductant Simulants, Glycolic Acid, And Antifoam 747

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, T. L.; Wiedenman, B. J.; Lambert, D. P.

amounts of impurities such as formic and diglycolic acid that were then carried over in the SME products. Oxalic acid present in the simulated tank farm waste was also detected. Finally, numerous other compounds, at low concentrations, were observed present in etheric extracts of aqueous supernate solutions of the SME samples and are thought to be breakdown products of antifoam 747. The data collectively suggest that although addition of glycolic acid and antifoam 747 will introduce a number of impurities and breakdown products into the melter feed, the concentrations of these organics is expected to remain low and may not significantly impact REDOX or off-gas flammability predictions. In the SME products examined presently, which contained variant amounts of glycolic acid and antifoam 747, no unexpected organic degradation product was found at concentrations above 500 mg/kg, a reasonable threshold concentration for an organic compound to be taken into account in the REDOX modeling. This statement does not include oxalic or formic acid that were sometimes observed above 500 mg/kg and acetic acid that has an analytical detection limit of 1250 mg/kg due to high glycolate concentration in the SME products tested. Once a finalized REDOX equation has been developed and implemented, REDOX properties of known organic species will be determined and their impact assessed. Although no immediate concerns arose during the study in terms of a negative impact of organics present in SME products of the glycolic flowsheet, evidence of antifoam degradation suggest that an alternative antifoam to antifoam 747 is worth considering. The determination and implementation of an antifoam that is more hydrolysis resistant would have benefits such as increasing its effectiveness over time and reducing the generation of degradation products.« less

Stereoregulations of pyrimidinone based chiral auxiliary in aldol and alkylation reactions: a convenient route to oxyneolignans.

PubMed

Chouhan, Mangilal; Sharma, Ratnesh; Nair, Vipin A

2012-11-16

(S)-4-Isopropyl-1-phenyltetrahydropyrimidin-2(1H)-one was synthesized and evaluated as a chiral auxiliary for asymmetric acetate and propionate aldol reactions, by generation of titanium and lithium enolates, affording excellent yields and stereoselectivities for syn and anti aldol diastereomers, respectively. High stereoselectivities were also obtained in lithium mediated alkylation reactions. The application of the auxiliary was exemplified in the asymmetric synthesis of a natural oxyneolignan, (+)-(7S,8S)-4-hydroxy-3,3',5'-trimethoxy-8',9'-dinor-8,4'-oxyneoligna-7,9-diol-7'-oic acid.

Direct asymmetric aldol reaction of aryl ketones with aryl aldehydes catalyzed by chiral BINOL-derived zincate catalyst.

PubMed

Li, Hong; Da, Chao-Shan; Xiao, Yu-Hua; Li, Xiao; Su, Ya-Ning

2008-09-19

Direct asymmetric aldol reaction of aryl ketones with aryl aldehydes catalyzed by chiral metal complex is reported for the first time herein. Two novel semicrown chiral ligands 1a and 1b were synthesized from (S)- and (R)-BINOL, respectively, and then employed to catalyze the direct asymmetric aldol addition of aryl ketones to aryl aldehydes. Introduced with 2.0 equiv of diethylzinc, 1b had higher enantioselectivity than 1a. Up to 97% yield and up to 80% enantioselectivity were achieved.

Molecular Hydrogen Formation from Proximal Glycol Pairs on TiO2(110)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Long; Li, Zhenjun; Smith, R. Scott

2014-04-16

Understanding hydrogen formation on TiO2 surfaces is of great importance as it could provide fundamental insight into water splitting for hydrogen production using solar energy. In this work, hydrogen formation from glycols having different numbers of methyl end-groups have been studied using temperature pro-grammed desorption on reduced, hydroxylated, and oxidized TiO2(110) surfaces. The results from OD-labeled glycols demon-strate that gas-phase molecular hydrogen originates exclusively from glycol hydroxyl groups. The yield is controlled by a combi-nation of glycol coverage, steric hindrance, TiO2(110) order and the amount of subsurface charge. Combined, these results show that proximal pairs of hydroxyl aligned glycol moleculesmore » and subsurface charge are required to maximize the yield of this redox reaction. These findings highlight the importance of geometric and electronic effects in hydrogen formation from adsorbates on TiO2(110).« less

Lewis base activation of Lewis acids: catalytic, enantioselective vinylogous aldol addition reactions.

PubMed

Denmark, Scott E; Heemstra, John R

2007-07-20

The generality of Lewis base catalyzed, Lewis acid mediated, enantioselective vinylogous aldol addition reactions has been investigated. The combination of silicon tetrachloride and chiral phosphoramides is a competent catalyst for highly selective additions of a variety of alpha,beta-unsaturated ketone-, 1,3-diketone-, and alpha,beta-unsaturated amide-derived dienolates to aldehydes. These reactions provided high levels of gamma-site selectivity for a variety of substitution patterns on the dienyl unit. Both ketone- and morpholine amide-derived dienol ethers afforded high enantio- and diastereoselectivity in the addition to conjugated aldehydes. Although alpha,beta-unsaturated ketone-derived dienolate did not react with aliphatic aldehydes, alpha,beta-unsaturated amide-derived dienolates underwent addition at reasonable rates affording high yields of vinylogous aldol product. The enantioselectivities achieved with the morpholine derived-dienolate in the addition to aliphatic aldehydes was the highest afforded to date with the silicon tetrachloride-chiral phosphoramide system. Furthermore, the ability to cleanly convert the morpholine amide to a methyl ketone was demonstrated.

A green route to methyl acrylate and acrylic acid by an aldol condensation reaction over H-ZSM-35 zeolite catalysts.

PubMed

Ma, Zhanling; Ma, Xiangang; Liu, Hongchao; He, Yanli; Zhu, Wenliang; Guo, Xinwen; Liu, Zhongmin

2017-08-10

A one-step aldol condensation reaction to produce MA and AA is a green and promising strategy. Here, the aldol condensation reaction was first conducted with DMM and MAc over different types of zeolite catalysts. The H-ZSM-35 zeolite demonstrates excellent catalytic performance with a DMM conversion of 100% and a MA + AA selectivity of up to 86.2% and superior regeneration ability, with great potential for industrial operation.

Liquid Quinones for Solvent-Free Redox Flow Batteries.

PubMed

Shimizu, Akihiro; Takenaka, Keisuke; Handa, Naoyuki; Nokami, Toshiki; Itoh, Toshiyuki; Yoshida, Jun-Ichi

2017-11-01

Liquid benzoquinone and naphthoquinone having diethylene glycol monomethyl ether groups are designed and synthesized as redox active materials that dissolve supporting electrolytes. The Li-ion batteries based on the liquid quinones using LiBF 4 /PC show good performance in terms of voltage, capacity, energy efficiency, and cyclability in both static and flow modes. A battery is constructed without using intentionally added organic solvent, and its high energy density (264 W h L -1 ) demonstrates the potential of solvent-free organic redox flow batteries using liquid active materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Regio- and Stereoselective Cascades via Aldol Condensation and 1,3-Dipolar Cycloaddition for Construction of Functional Pyrrolizidine Derivatives.

PubMed

Mao, Zhuo-Ya; Liu, Yi-Wen; Han, Pan; Dong, Han-Qing; Si, Chang-Mei; Wei, Bang-Guo; Lin, Guo-Qiang

2018-02-16

An efficient and step-economical approach to access functionalized pyrrolizidine derivatives by a one-pot tandem sequence, including an aldol condensation and subsequent 1,3-dipolar cycloaddition process, has been developed, starting from acetone, aldehyde, and proline. A number of substituted aromatic aldehydes were amenable to this transformation, and the desired products, racemic 7a-7w and chiral 9a-9m, were obtained with excellent regioselectivities and outstanding diastereoselectivities. Moreover, in situ NMR studies revealed MgSO 4 could effectively promote the aldol condensation pathway in this tandem process.

Redox-capacitor to connect electrochemistry to redox-biology.

PubMed

Kim, Eunkyoung; Leverage, W Taylor; Liu, Yi; White, Ian M; Bentley, William E; Payne, Gregory F

2014-01-07

It is well-established that redox-reactions are integral to biology for energy harvesting (oxidative phosphorylation), immune defense (oxidative burst) and drug metabolism (phase I reactions), yet there is emerging evidence that redox may play broader roles in biology (e.g., redox signaling). A critical challenge is the need for tools that can probe biologically-relevant redox interactions simply, rapidly and without the need for a comprehensive suite of analytical methods. We propose that electrochemistry may provide such a tool. In this tutorial review, we describe recent studies with a redox-capacitor film that can serve as a bio-electrode interface that can accept, store and donate electrons from mediators commonly used in electrochemistry and also in biology. Specifically, we (i) describe the fabrication of this redox-capacitor from catechols and the polysaccharide chitosan, (ii) discuss the mechanistic basis for electron exchange, (iii) illustrate the properties of this redox-capacitor and its capabilities for promoting redox-communication between biology and electrodes, and (iv) suggest the potential for enlisting signal processing strategies to "extract" redox information. We believe these initial studies indicate broad possibilities for enlisting electrochemistry and signal processing to acquire "systems level" redox information from biology.

Preparation of immobilized L-prolinamide via enzymatic polymerization of phenolic L-prolinamide and evaluation of its catalytic performance for direct asymmetric aldol reaction.

PubMed

Qu, Chengke; Zhao, Wenshan; Zhang, Lei; Cui, Yuanchen

2014-04-01

Phenolic L-prolinamide was allowed to participate in enzymatic polymerization with horseradish peroxidase as the catalyst, generating immobilized L-prolinamide. The catalytic performance of the resultant polymer-supported L-prolinamide for direct asymmetric aldol reaction between aromatic aldehyde and cyclohexanone was studied. The results show that as prepared L-prolinamide can catalyze the aldol reaction at room temperature in the presence of H2O. Relevant aldol addition products are obtained with good yields (up to 91%), high diastereoselectivities (up to 6:94 dr), and medium enantioselectivities (up to 87% ee). Moreover, the title polymer-supported catalyst can be recovered and reused for at least five cycles while the activity remains almost unchanged. Copyright © 2014 Wiley Periodicals, Inc.

Engineering the donor selectivity of D-fructose-6-phosphate aldolase for biocatalytic asymmetric cross-aldol additions of glycolaldehyde.

PubMed

Szekrenyi, Anna; Soler, Anna; Garrabou, Xavier; Guérard-Hélaine, Christine; Parella, Teodor; Joglar, Jesús; Lemaire, Marielle; Bujons, Jordi; Clapés, Pere

2014-09-22

D-Fructose-6-phosphate aldolase (FSA) is a unique catalyst for asymmetric cross-aldol additions of glycolaldehyde. A combination of a structure-guided approach of saturation mutagenesis, site-directed mutagenesis, and computational modeling was applied to construct a set of FSA variants that improved the catalytic efficiency towards glycolaldehyde dimerization up to 1800-fold. A combination of mutations in positions L107, A129, and A165 provided a toolbox of FSA variants that expand the synthetic possibilities towards the preparation of aldose-like carbohydrate compounds. The new FSA variants were applied as highly efficient catalysts for cross-aldol additions of glycolaldehyde to N-carbobenzyloxyaminoaldehydes to furnish between 80-98 % aldol adduct under optimized reaction conditions. Donor competition experiments showed high selectivity for glycolaldehyde relative to dihydroxyacetone or hydroxyacetone. These results demonstrate the exceptional malleability of the active site in FSA, which can be remodeled to accept a wide spectrum of donor and acceptor substrates with high efficiency and selectivity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kinetic and Mechanistic Examination of Acid–Base Bifunctional Aminosilica Catalysts in Aldol and Nitroaldol Condensations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collier, Virginia E.; Ellebracht, Nathan C.; Lindy, George I.

The kinetic and mechanistic understanding of cooperatively catalyzed aldol and nitroaldol condensations is probed using a series of mesoporous silicas functionalized with aminosilanes to provide bifunctional acid–base character. Mechanistically, a Hammett analysis is performed to determine the effects of electron-donating and electron-withdrawing groups of para-substituted benzaldehyde derivatives on the catalytic activity of each condensation reaction. This information is also used to discuss the validity of previously proposed catalytic mechanisms and to propose a revised mechanism with plausible reaction intermediates. For both reactions, electron-withdrawing groups increase the observed rates of reaction, though resonance effects play an important, yet subtle, role inmore » the nitroaldol condensation, in which a p-methoxy electron-donating group is also able to stabilize the proposed carbocation intermediate. Additionally, activation energies and pre-exponential factors are calculated via the Arrhenius analysis of two catalysts with similar amine loadings: one catalyst had silanols available for cooperative interactions (acid–base catalysis), while the other was treated with a silanol-capping reagent to prevent such cooperativity (base-only catalysis). The values obtained for activation energies and pre-exponential factors in each reaction are discussed in the context of the proposed mechanisms and the importance of cooperative interactions in each reaction. The catalytic activity decreases for all reactions when the silanols are capped with trimethylsilyl groups, and higher temperatures are required to make accurate rate measurements, emphasizing the vital role the weakly acidic silanols play in the catalytic cycles. The results indicate that loss of acid sites is more detrimental to the catalytic activity of the aldol condensation than the nitroaldol condensation, as evidenced by the significant decrease in the pre-exponential factor for the aldol

Kinetic and Mechanistic Examination of Acid–Base Bifunctional Aminosilica Catalysts in Aldol and Nitroaldol Condensations

DOE PAGES

Collier, Virginia E.; Ellebracht, Nathan C.; Lindy, George I.; ...

2015-12-09

The kinetic and mechanistic understanding of cooperatively catalyzed aldol and nitroaldol condensations is probed using a series of mesoporous silicas functionalized with aminosilanes to provide bifunctional acid–base character. Mechanistically, a Hammett analysis is performed to determine the effects of electron-donating and electron-withdrawing groups of para-substituted benzaldehyde derivatives on the catalytic activity of each condensation reaction. This information is also used to discuss the validity of previously proposed catalytic mechanisms and to propose a revised mechanism with plausible reaction intermediates. For both reactions, electron-withdrawing groups increase the observed rates of reaction, though resonance effects play an important, yet subtle, role inmore » the nitroaldol condensation, in which a p-methoxy electron-donating group is also able to stabilize the proposed carbocation intermediate. Additionally, activation energies and pre-exponential factors are calculated via the Arrhenius analysis of two catalysts with similar amine loadings: one catalyst had silanols available for cooperative interactions (acid–base catalysis), while the other was treated with a silanol-capping reagent to prevent such cooperativity (base-only catalysis). The values obtained for activation energies and pre-exponential factors in each reaction are discussed in the context of the proposed mechanisms and the importance of cooperative interactions in each reaction. The catalytic activity decreases for all reactions when the silanols are capped with trimethylsilyl groups, and higher temperatures are required to make accurate rate measurements, emphasizing the vital role the weakly acidic silanols play in the catalytic cycles. The results indicate that loss of acid sites is more detrimental to the catalytic activity of the aldol condensation than the nitroaldol condensation, as evidenced by the significant decrease in the pre-exponential factor for the aldol

Comparison of biodegradation of poly(ethylene glycol)s and poly(propylene glycol)s.

PubMed

Zgoła-Grześkowiak, Agnieszka; Grześkowiak, Tomasz; Zembrzuska, Joanna; Łukaszewski, Zenon

2006-07-01

The biodegradation of poly(ethylene glycol)s (PEGs) and poly(propylene glycol)s (PPGs), both being major by-products of non-ionic surfactants biodegradation, was studied under the conditions of the River Water Die-Away Test. PEGs were isolated from a water matrix using solid-phase extraction with graphitized carbon black sorbent, then derivatized with phenyl isocyanate and determined by HPLC with UV detection. PPGs were isolated from a water matrix by liquid-liquid extraction with chloroform, then derivatized with naphthyl isocyanate and determined by HPLC with fluorescence detection. The primary biodegradation of both PEGs and PPGs reached approximately 99% during the test. The tests show different biodegradation pathways of PEG and PPG. During PEG biodegradation, their chains are shortened leading to the formation of ethylene glycol and diethylene glycol. During PPG biodegradation, no short-chained biodegradation products were found.

Dynamic structural change of the self-assembled lanthanum complex induced by lithium triflate for direct catalytic asymmetric aldol-Tishchenko reaction.

PubMed

Horiuchi, Yoshihiro; Gnanadesikan, Vijay; Ohshima, Takashi; Masu, Hyuma; Katagiri, Kosuke; Sei, Yoshihisa; Yamaguchi, Kentaro; Shibasaki, Masakatsu

2005-09-05

The development of a direct catalytic asymmetric aldol-Tishchenko reaction and the nature of its catalyst are described. An aldol-Tishchenko reaction of various propiophenone derivatives with aromatic aldehydes was promoted by [LaLi3(binol)3] (LLB), and reactivity and enantioselectivity were dramatically enhanced by the addition of lithium trifluoromethanesulfonate (LiOTf). First, we observed a dynamic structural change of LLB by the addition of LiOTf using 13C NMR spectroscopy, electronspray ionization mass spectrometry (ESI-MS), and cold-spray ionization mass spectrometry (CSI-MS). X-ray crystallography revealed that the structure of the newly generated self-assembled complex was a binuclear [La2Li4(binaphthoxide)5] complex 6. A reverse structural change of complex 6 to LLB by the addition of one equivalent of Li2(binol) was also confirmed by ESI-MS and experimental results. The drastic concentration effects on the direct catalytic asymmetric aldol-Tishchenko reaction suggested that the addition of LiOTf to LLB generated an active oligomeric catalyst species.

Sludge batch 9 simulant runs using the nitric-glycolic acid flowsheet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambert, D. P.; Williams, M. S.; Brandenburg, C. H.

Testing was completed to develop a Sludge Batch 9 (SB9) nitric-glycolic acid chemical process flowsheet for the Defense Waste Processing Facility’s (DWPF) Chemical Process Cell (CPC). CPC simulations were completed using SB9 sludge simulant, Strip Effluent Feed Tank (SEFT) simulant and Precipitate Reactor Feed Tank (PRFT) simulant. Ten sludge-only Sludge Receipt and Adjustment Tank (SRAT) cycles and four SRAT/Slurry Mix Evaporator (SME) cycles, and one actual SB9 sludge (SRAT/SME cycle) were completed. As has been demonstrated in over 100 simulations, the replacement of formic acid with glycolic acid virtually eliminates the CPC’s largest flammability hazards, hydrogen and ammonia. Recommended processingmore » conditions are summarized in section 3.5.1. Testing demonstrated that the interim chemistry and Reduction/Oxidation (REDOX) equations are sufficient to predict the composition of DWPF SRAT product and SME product. Additional reports will finalize the chemistry and REDOX equations. Additional testing developed an antifoam strategy to minimize the hexamethyldisiloxane (HMDSO) peak at boiling, while controlling foam based on testing with simulant and actual waste. Implementation of the nitric-glycolic acid flowsheet in DWPF is recommended. This flowsheet not only eliminates the hydrogen and ammonia hazards but will lead to shorter processing times, higher elemental mercury recovery, and more concentrated SRAT and SME products. The steady pH profile is expected to provide flexibility in processing the high volume of strip effluent expected once the Salt Waste Processing Facility starts up.« less

Doubly Vinylogous Aldol Reaction of Furoate Esters with Aldehydes and Ketones.

PubMed

Hartwig, William T; Sammakia, Tarek

2017-01-06

The use of bulky Lewis acids, aluminum tris(2,6-diphenylphenoxide) (ATPH) and aluminum tris(2,6-di-2-naphthylphenoxide) (ATNP), in the doubly vinylogous aldol reaction between methyl-5-methyl-2-furoate and aldehydes or ketones is described. These reactions proceed smoothly and in high yields with both enolizable and non-enolizable substrates. This C-C bond-forming reaction enables a new bond construction for the synthesis of functionalized furans.

ALDOL- AND MANNICH-TYPE REACTIONS VIA IN SITU OLEFIN MIGRATION IN IONIC LIQUID

EPA Science Inventory

An aldol-type and a Mannich-type reaction via the cross-coupling of aldehydes and imines with allylic alcohols catalyzed by RuCl2(PPh3)3 was developed with ionic liquid as the solvent. The solvent/catalyst system could be reused for at least five times with no loss of reactiv...

RUTHENIUM-CATALYZED TANDEM OLEFIN MIGRATION-ALDOL AND MANNICH-TYPE REACTIONS IN IONIC LIQUID.

EPA Science Inventory

In the presence of a catalytic amount of RuCl2(PPh3)3, a cross-coupling of 3-buten-2-ol with aldehydes and imines was developed via a tandem olefin migration--aldol--Mannich reaction in bmim[PF6]. With In(OAc)3 as a co-catalyst, a-vinylbenzyl alcohol and aldehydes underwent sim...

Decarboxylative aldol reactions of allyl beta-keto esters via heterobimetallic catalysis.

PubMed

Lou, Sha; Westbrook, John A; Schaus, Scott E

2004-09-22

Mild and selective heterobimetallic-catalyzed decarboxylative aldol reactions involving allyl beta-keto esters have been developed. The reaction is promoted by Pd(0)- and Yb(III)-DIOP complexes at room temperature and involves the in situ formation of a ketone enolate from allyl beta-keto esters followed by addition of the enolate to aldehydes. The reaction is a new example of heterobimetallic catalysis in which the optimized reaction conditions require the addition of both metals.

Redox-responsive nanoparticles with Aggregation-Induced Emission (AIE) characteristic for fluorescence imaging.

PubMed

Cheng, Weiren; Wang, Guan; Pan, Xiaoyong; Zhang, Yong; Tang, Ben Zhong; Liu, Ye

2014-08-01

The redox environment between intracellular compartments and extracellular matrix is significantly different, and the cellular redox homeostasis determines many physiological functions. Here, redox-responsive nanoparticles with aggregation-induced emission (AIE) characteristic for fluorescence imaging are developed by encapsulation of fluorophore with redox "turn-on" AIE characteristic, TPE-MI, into the micelles of poly(ethylene glycol) (PEG)- and cholesterol (CE)-conjugated disulfide containing poly(amido amine)s. The redox-responsive fluorescence profiles of the nanoparticles are investigated after reaction with glutathione (GSH). The encapsulation of TPE-MI in micelles leads to a higher efficiency and red shift in emission, and the fluorescence intensity of the nanoparticles increases with the concentration of GSH. Confocal microscopy imaging shows that the nanoparticles can provide obvious contrast between the intracellular compartments and the extracellular matrix in MCF-7 and HepG2 cells. So the nanoparticles with PEG shells and low cytotoxicity are promising to provide fluorescence bioimaging with a high contrast and for differentiation of cellular redox environment. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A General Diastereoselective Catalytic Vinylogous Aldol Reaction Among Tetramic Acid-Derived Pyrroles

PubMed Central

2015-01-01

A catalytic diastereoselective aldol reaction has been developed for N1-arylated/C2-O-silylated/C3-methylated and brominated/C4-O-methylated pyrroles in its reactions with various aldehydes. Syn adducts emerge with regard to the vicinal nitrogen and oxygen heteroatom substituents. The N1-aryl residue undergoes oxidative cleavage, and the C3-bromine atom undergoes palladium-mediated coupling reactions, both without disturbing the newly created stereocenters. PMID:25119431

Mineral catalysis of a potentially prebiotic aldol condensation

NASA Technical Reports Server (NTRS)

De Graaf, R. M.; Visscher, J.; Xu, Y.; Arrhenius, G.; Schwartz, A. W.

1998-01-01

Minerals may have played a significant role in chemical evolution. In the course of investigating the chemistry of phosphonoacetaldehyde (PAL), an analogue of glycolaldehyde phosphate, we have observed a striking case of catalysis by the layered hydroxide mineral hydrotalcite ([Mg2Al(OH)6][Cl.nH2O]). In neutral or moderately basic aqueous solutions, PAL is unreactive even at a concentration of 0.1 M. In the presence of a large excess of NaOH (2 M), the compound undergoes aldol condensation to produce a dimer containing a C3-C4 double-bond. In dilute neutral solutions and in the presence of the mineral, however, condensation takes place rapidly, to produce a dimer which is almost exclusively the C2-C3 unsaturated product.

Anaerobic treatability of wastewater contaminated with propylene glycol.

PubMed

Sezgin, Naim; Tonuk, Gulseven Ubay

2013-09-01

The purpose of this study was to investigate the biodegradability of propylene glycol in anaerobic conditions by using methanogenic culture. A master reactor was set up to develop a culture that would be acclimated to propylene glycol. After reaching steady-state, culture was transferred to serum bottles. Three reactors with same initial conditions were run for consistency. Propylene glycol was completely biodegradable under anaerobic methanogenic conditions. Semi-continuous reactors operated at a temperature of 35°C had consistently achieved a propylene glycol removal of higher than 95 % based on chemical oxygen demand (COD). It was found that in semi-continuous reactors, anaerobic treatment of propylene glycol at concentrations higher than 1,500 mg COD m(-3) day(-1) was not convenient due to instable effluent COD.

Organic chemical degradation by remote study of the redox conditions

NASA Astrophysics Data System (ADS)

Fernandez, P. M.; Revil, A.; Binley, A. M.; Bloem, E.; French, H. K.

2014-12-01

Monitoring the natural (and enhanced) degradation of organic contaminants is essential for managing groundwater quality in many parts of the world. Contaminated sites often have limited access, hence non-intrusive methods for studying redox processes, which drive the degradation of organic compounds, are required. One example is the degradation of de-icing chemicals (glycols and organic salts) released to the soil near airport runways during winter. This issue has been broadly studied at Oslo airport, Gardermoen, Norway using intrusive and non-intrusive methods. Here, we report on laboratory experiments that aim to study the potential of using a self-potential, DCresistivity, and time-domain induced polarization for geochemical characterization of the degradation of Propylene Glycol (PG). PG is completely miscible in water, does not adsorb to soil particles and does not contribute to the electrical conductivity of the soil water. When the contaminant is in the unsaturated zone near the water table, the oxygen is quickly consumed and the gas exchange with the surface is insufficient to ensure aerobic degradation, which is faster than anaerobic degradation. Since biodegradation of PG is highly oxygen demanding, anaerobic pockets can exist causing iron and manganese reduction. It is hypothesised that nitrate would boost the degradation rate under such conditions. In our experiment, we study PG degradation in a sand tank. We provide the system with an electron highway to bridge zones with different redox potential. This geo-battery system is characterized by self-potential, resistivity and induced polarization anomalies. An example of preliminary results with self-potential at two different times of the experiment can be seen in the illustration. These will be supplemented with more direct information on the redox chemistry: in-situ water sampling, pH, redox potential and electrical conductivity measurements. In parallel, a series of batch experiments have been

Defense Waste Processing Facility Nitric- Glycolic Flowsheet Chemical Process Cell Chemistry: Part 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zamecnik, J.; Edwards, T.

The conversions of nitrite to nitrate, the destruction of glycolate, and the conversion of glycolate to formate and oxalate were modeled for the Nitric-Glycolic flowsheet using data from Chemical Process Cell (CPC) simulant runs conducted by Savannah River National Laboratory (SRNL) from 2011 to 2016. The goal of this work was to develop empirical correlation models to predict these values from measureable variables from the chemical process so that these quantities could be predicted a-priori from the sludge or simulant composition and measurable processing variables. The need for these predictions arises from the need to predict the REDuction/OXidation (REDOX) statemore » of the glass from the Defense Waste Processing Facility (DWPF) melter. This report summarizes the work on these correlations based on the aforementioned data. Previous work on these correlations was documented in a technical report covering data from 2011-2015. This current report supersedes this previous report. Further refinement of the models as additional data are collected is recommended.« less

Effects of Schiff Base Formation and Aldol Condensation on the Determination of Aldehydes in Rice Wine Using GC-MS.

PubMed

Han, Ji Hye; Lee, Sang Mi; Kim, Young-Suk

2017-04-11

The Schiff base reaction and aldol condensation that occur during sample preparation can lead to the reduction of aldehyde content in the analysis of traditional Korean rice wine, makgeolli. The contents of aldehydes were decreased, whereas those of hydroxy carbonyl compounds were increased by increasing the pH. In the presence of added amino acids, the levels of aldehydes in makgeolli were reduced as the amount of the amino acid alanine increased. Also, the contents of hydroxyl carbonyl compounds were reduced by alanine addition as compared to the control. Therefore, the determination of aldehydes can be affected by pH and the amount of amino acids, which can vary during fermentation and storage of alcoholic beverages because pH and amino acids affect Schiff base formation and aldol condensation.

TANDEM BIS-ALDOL REACTION OF KETONES: A FACILE ONE-POT SYNTHESIS OF 1,3-DIOXANES IN AQUEOUS MEDIUM

EPA Science Inventory

A novel tandem bis-aldol reaction of ketone with paraformaldehyde catalyzed by polystyrenesulfonic acid in aqueous medium delivers 1,3-dioxanes in high yield. This one pot, operationally simple microwave-assisted synthetic protocol proceeds efficiently in water in the absence of ...

Dinuclear Zinc-Prophenol-Catalyzed Enantioselective α-Hydroxyacetate Aldol Reaction with Activated Ester Equivalents

PubMed Central

Trost, Barry M.; Michaelis, David J.; Truica, Mihai I.

2013-01-01

An enantioselective α-hydroxyacetate aldol reaction that employs N-acetyl pyrroles as activated ester equivalents and generates syn 1,2-diols in good yield and diastereoselectivity is reported. This dinuclear zinc Prophenol-catalyzed transformation proceeds with high enantioselectivity with a wide variety of substrates including aryl, alyl, and alkenyl aldehydes. The resulting α,β-dihydroxy activated esters are versatile intermediates for the synthesis of a variety of carboxylic acid derivatives including amides, esters, and unsymmetrical ketones. PMID:23947595

Glycol leak detection system

NASA Astrophysics Data System (ADS)

Rabe, Paul; Browne, Keith; Brink, Janus; Coetzee, Christiaan J.

2016-07-01

MonoEthylene glycol coolant is used extensively on the Southern African Large Telescope to cool components inside the telescope chamber. To prevent coolant leaks from causing serious damage to electronics and optics, a Glycol Leak Detection System was designed to automatically shut off valves in affected areas. After two years of research and development the use of leaf wetness sensors proved to work best and is currently operational. These sensors are placed at various critical points within the instrument payload that would trigger the leak detector controller, which closes the valves, and alerts the building management system. In this paper we describe the research of an initial concept and the final accepted implementation and the test results thereof.

Effect of end segment on physicochemical properties and platelet compatibility of poly(propylene glycol)-initiated poly(methyl methacrylate).

PubMed

Fukuda, Chihiro; Yahata, Chie; Kinoshita, Takuya; Watanabe, Takafumi; Tsukamoto, Hideo; Mochizuki, Akira

2017-10-01

It is well known that polyether-based copolymers have good blood compatibility, although many mechanisms have been proposed to explain their favorable performance. Our objective in carrying out the present study was to obtain a better understanding of the effect of the (poly)ether segment on blood compatibility. Therefore, we synthesized poly(propylene glycol) (PPG)-based initiators for atom transfer polymerization, where the number of propylene glycol (PG) units in the PPG (Pn(PG) was varied from 1 to 94. Methyl methacrylate (MMA) was polymerized using the initiators, resulting in the formation of polyMMAs with a PG-based ether part at the polymer terminal. We mainly investigated the effects of Pn(PG) on the surface properties and platelet compatibility of the PPG-polyMMA. X-ray photoelectron spectroscopy and surface contact angle (CA) analysis revealed the exposure of the PG units at the surface of the polymer. The platelet compatibility of the polymers was improved compared with a commercial polyMMA, even when Pn(PG) = 1. These results suggest that PG units have an important influence on favorable blood compatibility, regardless of the Pn(PG) value. We also investigated protein adsorption behavior in terms of the amount and deformation of fibrinogen adsorbed on the polymer surface.

Unraveling the role of water in the stereoselective step of aqueous proline-catalyzed aldol reactions.

PubMed

Ribas-Arino, Jordi; Carvajal, Maria Angels; Chaumont, Alain; Masia, Marco

2012-12-03

A multiscale computational study was performed with the aim of tracing the source of stereoselectivity and disclosing the role of water in the stereoselective step of propionaldehyde aldol self-condensation catalyzed by proline amide in water, a reaction that serves as a model for aqueous organocatalytic aldol condensations. Solvent mixing and hydration behavior were assessed by classical molecular dynamics simulations, which show that the reaction between propanal and the corresponding enamine takes place in a fully hydrated environment. First-principles molecular dynamics simulations were used to study the free-energy profile of four possible reaction paths, each of which yields a different stereoisomer, and high-level static first-principles calculations were employed to characterize the transition states for microsolvated species. The first solvation shell of the oxygen atom of the electrophilic aldehyde at the transition states contains two water molecules, each of which donates one hydrogen bond to the nascent alkoxide and thereby largely stabilizes its excess electron density. The stereoselectivity originates in an extra hydrogen bond donated by the amido group of proline amide in two reaction paths. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel Redox-Responsive Amphiphilic Copolymer Micelles for Drug Delivery: Synthesis and Characterization.

PubMed

Bae, Jungeun; Maurya, Abhijeet; Shariat-Madar, Zia; Murthy, S Narasimha; Jo, Seongbong

2015-11-01

A novel redox-responsive amphiphilic polymer was synthesized with bioreductive trimethyl-locked quinone propionic acid for a potential triggered drug delivery application. The aim of this study was to synthesize and characterize the redox-responsive amphiphilic block copolymer micelles containing pendant bioreductive quinone propionic acid (QPA) switches. The redox-responsive hydrophobic block (polyQPA), synthesized from QPA-serinol and adipoyl chloride, was end-capped with methoxy poly(ethylene glycol) of molecular weight 750 (mPEG750) to achieve a redox-responsive amphiphilic block copolymer, polyQPA-mPEG750. PolyQPA-mPEG750 was able to self-assemble as micelles to show a critical micelle concentration (CMC) of 0.039% w/v (0.39 mg/ml, 0.107 mM) determined by a dye solubilization method using 1,6-diphenyl-1,3,5-hexatriene (DPH) in phosphate-buffered saline (PBS). The mean diameter of polymeric micelles was found to be 27.50 nm (PI = 0.064) by dynamic light scattering. Furthermore, redox-triggered destabilization of the polymeric micelles was confirmed by (1)H-NMR spectroscopy and particle size measurements in a simulated redox state. PolyQPA-mPEG750 underwent triggered reduction to shed pendant redox-responsive QPA groups and its polymeric micelles were swollen to be dissembled in the presence of a reducing agent, thereby enabling the release of loaded model drug, paclitaxel. The redox-responsive polyQPA-mPEG750 polymer micelles would be useful as a drug delivery system allowing triggered drug release in an altered redox state such as tumor microenvironments with an altered redox potential and/or redox enzyme upregulation.

Surface-initiated polymerization within mesoporous silica spheres for the modular design of charge-neutral polymer particles.

PubMed

Müllner, Markus; Cui, Jiwei; Noi, Ka Fung; Gunawan, Sylvia T; Caruso, Frank

2014-06-03

We report a templating approach for the preparation of functional polymer replica particles via surface-initiated polymerization in mesoporous silica templates. Subsequent removal of the template resulted in discrete polymer particles. Furthermore, redox-responsive replica particles could be engineered to disassemble in a reducing environment. Particles, made of poly(methacryloyloxyethyl phosphorylcholine) (PMPC) or poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA), exhibited very low association to human cancer cells (below 5%), which renders the reported charge-neutral polymer particles a modular and versatile class of highly functional carriers with potential applications in drug delivery.

Investigation of selected potential environmental contaminants: ethylene glycol, propylene glycols and butylene glycols. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, L.M.

1979-05-01

This report reviews aspects of production, use, environmental exposure and biological effects of ethylene glycol, two isomers of propylene glycol (1,2- and 1,3-propanediol) and four isomers of butylene glycol (1,3-, 1,4-, 2,3-, and 1,2- butanediol). Annual production of ethylene glycol is about 3.7 billion pounds for use primarily in antifreeze and polyester fiber. About 0.5 billion pounds of 1,2-propanediol are produced per year for use in polyester resins, food, pharmaceuticals, and cellophane. Annual domestic demand for 1,4-butanediol is about 0.2 billion pounds for use in the production of tetra-hydrofuran and acetylenic chemicals. The other title glycols are of less importancemore » commercially. The major source of environmental contamination by ethylene glycol and 1,2-propanediol is likely from the disposal of spent antifreeze and de-icing fluids. However, limited monitoring data make it difficult to adequately assess environmental exposure to the glycols. The glycols are capable of being degraded by a variety of acclimated and unacclimated soil, water, and sewage microorganisms. In humans, ethylene glycol intoxication, usually as a result of accidental ingestion of antifreeze, may result in nausea, hypertension, tachycardia, cardiopulmonary failure, renal impairment, coma and death. 1,2-Propanediol is a GRAS food additive of low toxicity. 1,3-Butanediol has been studied as a source of dietary energy. Few studies are available on 1,2-, 2,3- and 1,4-butanediol or on 1,3-propanediol.« less

Degradation of ethylene glycol and polyethylene glycols by methanogenic consortia.

PubMed Central

Dwyer, D F; Tiedje, J M

1983-01-01

Methanogenic enrichments capable of degrading polyethylene glycol and ethylene glycol were obtained from sewage sludge. Ethanol, acetate, methane, and (in the case of polyethylene glycols) ethylene glycol were detected as products. The sequence of product formation suggested that the ethylene oxide unit [HO-(CH2-CH2-O-)xH] was dismutated to acetate and ethanol; ethanol was subsequently oxidized to acetate by a syntrophic association that produced methane. The rates of degradation for ethylene, diethylene, and polyethylene glycol with molecular weights of 400, 1,000, and 20,000, respectively, were inversely related to the number of ethylene oxide monomers per molecule and ranged from 0.84 to 0.13 mM ethylene oxide units degraded per h. The enrichments were shown to best metabolize glycols close to the molecular weight of the substrate on which they were enriched. The anaerobic degradation of polyethylene glycol (molecular weight, 20,000) may be important in the light of the general resistance of polyethylene glycols to aerobic degradation. PMID:6614903

Forging Fluorine‐Containing Quaternary Stereocenters by a Light‐Driven Organocatalytic Aldol Desymmetrization Process

PubMed Central

Cuadros, Sara; Dell'Amico, Luca

2017-01-01

Abstract Reported herein is a light‐triggered organocatalytic strategy for the desymmetrization of achiral 2‐fluoro‐substituted cyclopentane‐1,3‐diketones. The chemistry is based on an intermolecular aldol reaction of photochemically generated hydroxy‐o‐quinodimethanes and simultaneously forges two adjacent fully substituted carbon stereocenters, with one bearing a stereogenic carbon–fluorine unit. The method uses readily available substrates, a simple chiral organocatalyst, and mild reaction conditions to afford an array of highly functionalized chiral 2‐fluoro‐3‐hydroxycyclopentanones. PMID:28746742

Propylene glycol accumulation in critically ill patients receiving continuous intravenous lorazepam infusions.

PubMed

Horinek, Erica L; Kiser, Tyree H; Fish, Douglas N; MacLaren, Robert

2009-12-01

Lorazepam is recommended by the Society of Critical Care Medicine as the preferred agent for sedation of critically ill patients. Intravenous lorazepam contains propylene glycol, which has been associated with toxicity when high doses of lorazepam are administered. To evaluate the accumulation of propylene glycol in critically ill patients receiving lorazepam by continuous infusion and determine factors associated with propylene glycol concentration. A 6-month, retrospective, safety assessment was conducted of adults admitted to the medical intensive care unit who were receiving lorazepam by continuous infusion for 12 hours or more. Propylene glycol serum concentrations were obtained 24-48 hours after continuous-infusion lorazepam was initiated and every 3-5 days thereafter. Propylene glycol accumulation was defined as concentrations of 25 mg/dL or more. Groups with and without propylene glycol accumulation were compared and factors associated with propylene glycol concentration were determined using multivariate correlation regression analyses. Forty-eight propylene glycol serum samples were obtained from 33 patients. Fourteen (42%) patients had propylene glycol accumulation, representing 23 (48%) serum samples. Univariate analyses showed the following factors were related to propylene glycol accumulation: baseline renal dysfunction, presence of alcohol withdrawal, sex, age, Acute Physiology and Chronic Health Evaluation (APACHE II) score, rate of lorazepam continuous infusion, and 24-hour lorazepam dose. Multivariate linear regression modeling demonstrated that propylene glycol concentration was strongly associated with the continuous infusion rate and 24-hour dose (adjusted r(2) > or = 0.77; p < 0.001). Independent correlation analyses showed that these 2 variables were so strongly associated with propylene glycol concentration (r(2) > or = 0.71; p < 0.001) that they alone predicted propylene glycol concentration. Seven (21%) patients developed renal dysfunction

Forging Fluorine-Containing Quaternary Stereocenters by a Light-Driven Organocatalytic Aldol Desymmetrization Process.

PubMed

Cuadros, Sara; Dell'Amico, Luca; Melchiorre, Paolo

2017-09-18

Reported herein is a light-triggered organocatalytic strategy for the desymmetrization of achiral 2-fluoro-substituted cyclopentane-1,3-diketones. The chemistry is based on an intermolecular aldol reaction of photochemically generated hydroxy-o-quinodimethanes and simultaneously forges two adjacent fully substituted carbon stereocenters, with one bearing a stereogenic carbon-fluorine unit. The method uses readily available substrates, a simple chiral organocatalyst, and mild reaction conditions to afford an array of highly functionalized chiral 2-fluoro-3-hydroxycyclopentanones. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

A One-Pot Tandem Strategy in Catalytic Asymmetric Vinylogous Aldol Reaction of Homoallylic Alcohols.

PubMed

Hou, Xufeng; Jing, Zhenzhong; Bai, Xiangbin; Jiang, Zhiyong

2016-06-27

Reported is a rationally-designed one-pot sequential strategy that allows homoallylic alcohols to be employed in a catalytic, asymmetric, direct vinylogous aldol reaction with a series of activated acyclic ketones, including trifluoromethyl ketones, γ-ketoesters, and α-keto phosphonates, in high yields (up to 95%) with excellent regio- and enantio-selectivity (up to 99% ee). This modular combination, including Jones oxidation and asymmetric organocatalysis, has satisfactory compatibility and reliability even at a 20 mmol scale, albeit without intermediary purification.

Synthesis of Chiral 1,2-Oxazinanes and Isoxazolidines via Nitroso Aldol Reaction of Distal Dialdehydes.

PubMed

Ramakrishna, Isai; Ramaraju, Panduga; Baidya, Mahiuddin

2018-02-16

The first catalytic enantioselective nitroso aldol reaction of distal dialdehydes is reported. The reaction is catalyzed by simple l-proline at room temperature and subsequent reduction delivered biologically potent and synthetically versatile N-O bond containing five- and six-membered heterocycles, 1,2-oxazinanes, and isoxazolidines in high yields and excellent enantioselectivities (up to >99% ee). The method was further exploited to prepare chiral 3-hydroxypiperidines and -pyrrolidines that are otherwise difficult to access.

Polyethylene glycol without electrolytes for children with constipation and encopresis.

PubMed

Loening-Baucke, Vera

2002-04-01

Children with functional constipation and encopresis benefit from behavior modification and from long-term laxative medication. Polyethylene glycol without electrolytes has become the first option for many pediatric gastroenterologists. Twenty-eight children treated with polyethylene glycol without electrolytes were compared with 21 children treated with milk of magnesia to evaluate the efficiency, acceptability, side effects, and treatment dosage of polyethylene glycol in long-term treatment of functional constipation and encopresis. Children were rated as "doing well," "improved," or "not doing well," depending on resolution of constipation and encopresis. At the 1-, 3-, 6-, and 12-month follow-ups, bowel movement frequency increased and soiling frequency decreased significantly in both groups. At the 1-month follow-up, children on polyethylene glycol were soiling more frequently (P < 0.01) and fewer were improved (P < 0.01). At the 3- and 6-month follow-ups, both groups had similarly improved. At the 12-month visit, 61% of children on polyethylene glycol and 67% of children on milk of magnesia were doing well. Children on polyethylene glycol soiled more frequently (P < 0.01). None refused polyethylene glycol, but 33% refused to take milk of magnesia. The mean initial treatment dosage of polyethylene glycol was 0.6 +/- 0.2 g/kg daily. Polyethylene glycol had no taste, and no loss of efficacy occurred. Polyethylene glycol did not cause clinically significant side effects. Polyethylene glycol without electrolytes is an alternative for long-term management of children with constipation and encopresis.

Comparison of retention models for polymers 1. Poly(ethylene glycol)s.

PubMed

Bashir, Mubasher A; Radke, Wolfgang

2006-10-27

The suitability of three different retention models to predict the retention times of poly(ethylene glycol)s (PEGs) in gradient and isocratic chromatography was investigated. The models investigated were the linear (LSSM) and the quadratic solvent strength model (QSSM). In addition, a model describing the retention behaviour of polymers was extended to account for gradient elution (PM). It was found that all models are suited to properly predict gradient retention volumes provided the extraction of the analyte specific parameters is performed from gradient experiments as well. The LSSM and QSSM on principle cannot describe retention behaviour under critical or SEC conditions. Since the PM is designed to cover all three modes of polymer chromatography, it is therefore superior to the other models. However, the determination of the analyte specific parameters, which are needed to calibrate the retention behaviour, strongly depend on the suitable selection of initial experiments. A useful strategy for a purposeful selection of these calibration experiments is proposed.

Direct asymmetric aldol reactions between aldehydes and ketones catalyzed by L-tryptophan in the presence of water.

PubMed

Jiang, Zhaoqin; Yang, Hui; Han, Xiao; Luo, Jie; Wong, Ming Wah; Lu, Yixin

2010-03-21

Primary amino acids and their derivatives were investigated as catalysts for the direct asymmetric aldol reactions between ketones and aldehydes in the presence of water, and L-tryptophan was shown to be the best catalyst. Solvent effects, substrate scope and the influence of water on the reactions were investigated. Quantum chemical calculations were performed to understand the origin of the observed stereoselectivity.

Asymmetric vinylogous Mukaiyama aldol reaction of isatins under bifunctional organocatalysis: enantioselective synthesis of substituted 3-hydroxy-2-oxindoles.

PubMed

Laina-Martín, Víctor; Humbrías-Martín, Jorge; Fernández-Salas, José A; Alemán, José

2018-03-13

A highly enantioselective organocatalytic vinylogous Mukaiyama aldol reaction of silyloxy dienes and isatins under bifunctional organocatalysis is presented. Substituted 3-hydroxy-2-oxindoles are synthesised in good yields and enantioselectivities. These synthetic intermediates are used for the construction of more complex molecules with biological properties such as the formal synthesis of a CB2 agonist presented.

Highly enantioselective asymmetric direct aldol reaction promoted by aziridine amides constructed on chiral terpene scaffold.

PubMed

Wujkowska, Zuzanna; Strojewska, Aleksandra; Pieczonka, Adam M; Leśniak, Stanisław; Rachwalski, Michał

2017-05-01

Optically pure, diastereomeric aziridine amides built on the chiral skeletons of camphor, fenchone, and menthone have proven to be highly efficient ligands for enantioselective asymmetric direct aldol reaction in the presence of water and zinc triflate. Desired products were formed in moderate to high chemical yields (up to 95%) and with enantiomeric excess up to 99%. The influence of the stereogenic centers located at the aziridine subunit on the stereochemical course of the reaction is discussed. © 2017 Wiley Periodicals, Inc.

Engineering Folate-Targeting Diselenide-containing Triblock Copolymer as a Redox-Responsive Shell-sheddable Micelle for Antitumor Therapy In Vivo.

PubMed

Behroozi, Farnaz; Abdkhodaie, Mohammad-Jafar; Sadeghi Abandansari, Hamid; Satarian, Leila; Molazem, Mohammad; Al-Jamal, Khuloud T; Baharvand, Hossein

2018-06-18

The oxidation-reduction (redox)-responsive micelle system is based on a diselenide-containing triblock copolymer, poly(ε-caprolactone)-bis(diselenide-methoxy poly(ethylene glycol)/poly(ethylene glycol)-folate) [PCL-(SeSe-mPEG/PEG-FA) 2 ]. This has helped in the development of tumor-targeted delivery for hydrophobic anticancer drugs. The diselenide bond, as a redox-sensitive linkage, was designed in such a manner that it is located at the hydrophilic-hydrophobic hinge to allow complete collapse of the micelle and thus efficient drug release in redox environments. The amphiphilic block copolymers self-assembled into micelles at concentrations higher than the critical micelle concentration (CMC) in an aqueous environment. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses showed that the micelles were spherical with an average diameter of 120 nm. The insoluble anticancer drug paclitaxel (PTX) was loaded into micelles, and its triggered release behavior under different redox conditions was verified. Folate-targeting micelles showed an enhanced uptake in 4T1 breast cancer cells and in vitro cytotoxicity by flow cytometry and (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay, respectively. Delayed tumor growth was confirmed in the subcutaneously implanted 4T1 breast cancer in mice after intraperitoneal injection. The proposed redox-responsive copolymer offers a new type of biomaterial for drug delivery into cancer cells in vivo. On-demand drug actuation is highly desired. Redox-responsive polymeric DDSs have been shown to be able to respond and release their cargo in a selective manner when encountering a significant change in the potential difference, such as that present between cancerous and healthy tissues. This study offers an added advantage to the field of redox-responsive polymers by reporting a new type of shell-sheddable micelle based on an amphiphilic triblock co

Compromised redox homeostasis, altered nitroso–redox balance, and therapeutic possibilities in atrial fibrillation

PubMed Central

Simon, Jillian N.; Ziberna, Klemen; Casadei, Barbara

2016-01-01

Although the initiation, development, and maintenance of atrial fibrillation (AF) have been linked to alterations in myocyte redox state, the field lacks a complete understanding of the impact these changes may have on cellular signalling, atrial electrophysiology, and disease progression. Recent studies demonstrate spatiotemporal changes in reactive oxygen species production shortly after the induction of AF in animal models with an uncoupling of nitric oxide synthase activity ensuing in the presence of long-standing persistent AF, ultimately leading to a major shift in nitroso–redox balance. However, it remains unclear which radical or non-radical species are primarily involved in the underlying mechanisms of AF or which proteins are targeted for redox modification. In most instances, only free radical oxygen species have been assessed; yet evidence from the redox signalling field suggests that non-radical species are more likely to regulate cellular processes. A wider appreciation for the distinction of these species and how both species may be involved in the development and maintenance of AF could impact treatment strategies. In this review, we summarize how redox second-messenger systems are regulated and discuss the recent evidence for alterations in redox regulation in the atrial myocardium in the presence of AF, while identifying some critical missing links. We also examine studies looking at antioxidants for the prevention and treatment of AF and propose alternative redox targets that may serve as superior therapeutic options for the treatment of AF. PMID:26786158

Redox electrodeposition polymers: adaptation of the redox potential of polymer-bound Os complexes for bioanalytical applications.

PubMed

Guschin, Dmitrii A; Castillo, John; Dimcheva, Nina; Schuhmann, Wolfgang

2010-10-01

The design of polymers carrying suitable ligands for coordinating Os complexes in ligand exchange reactions against labile chloro ligands is a strategy for the synthesis of redox polymers with bound Os centers which exhibit a wide variation in their redox potential. This strategy is applied to polymers with an additional variation of the properties of the polymer backbone with respect to pH-dependent solubility, monomer composition, hydrophilicity etc. A library of Os-complex-modified electrodeposition polymers was synthesized and initially tested with respect to their electron-transfer ability in combination with enzymes such as glucose oxidase, cellobiose dehydrogenase, and PQQ-dependent glucose dehydrogenase entrapped during the pH-induced deposition process. The different polymer-bound Os complexes in a library containing 50 different redox polymers allowed the statistical evaluation of the impact of an individual ligand to the overall redox potential of an Os complex. Using a simple linear regression algorithm prediction of the redox potential of Os complexes becomes feasible. Thus, a redox polymer can now be designed to optimally interact in electron-transfer reactions with a selected enzyme.

Bactericidal activity of propylene glycol, glycerine, polyethylene glycol 400, and polyethylene glycol 1000 against selected microorganisms

PubMed Central

Nalawade, Triveni Mohan; Bhat, Kishore; Sogi, Suma H. P.

2015-01-01

Aim: The aim of the present study was to evaluate the bactericidal activity of propylene glycol, glycerine, polyethylene glycol 400 (PEG 400), and polyethylene glycol 1000 (PEG 1000) against selected microorganisms in vitro. Materials and Methods: Five vehicles, namely propylene glycol, glycerine, PEG 400, PEG 1000, and combination of propylene glycol with PEG 400, were tested for their bactericidal activity. The minimum bactericidal concentration was noted against four standard strains of organisms, i.e. Streptococcus mutans American Type Culture Collection (ATCC) 25175, Streptococcus mutans ATCC 12598, Enterococcus faecalis ATCC 35550, and Escherichia coli ATCC 25922, using broth dilution assay. Successful endodontic therapy depends upon thorough disinfection of root canals. In some refractory cases, routine endodontic therapy is not sufficient, so intracanal medicaments are used for proper disinfection of canals. Intracanal medicaments are dispensed with vehicles which aid in increased diffusion through the dentinal tubules and improve their efficacy. Among the various vehicles used, glycerine is easily available, whereas others like propylene glycol and polyethylene glycol have to be procured from appropriate sources. Also, these vehicles, being viscous, aid in sustained release of the medicaments and improve their handling properties. The most commonly used intracanal medicaments like calcium hydroxide are ineffective on many microorganisms, while most of the other medicaments like MTAD (Mixture of Tetracycline, an Acid, and a Detergent) and Triple Antibiotic Paste (TAP) consist of antibiotics which can lead to development of antibiotic resistance among microorganisms. Thus, in order to use safer and equally effective intracanal medicaments, newer alternatives like chlorhexidine gluconate, ozonized water, etc., are being explored. Similarly, the five vehicles mentioned above are being tested for their antimicrobial activity in this study. Results: All vehicles

Bactericidal activity of propylene glycol, glycerine, polyethylene glycol 400, and polyethylene glycol 1000 against selected microorganisms.

PubMed

Nalawade, Triveni Mohan; Bhat, Kishore; Sogi, Suma H P

2015-01-01

The aim of the present study was to evaluate the bactericidal activity of propylene glycol, glycerine, polyethylene glycol 400 (PEG 400), and polyethylene glycol 1000 (PEG 1000) against selected microorganisms in vitro. Five vehicles, namely propylene glycol, glycerine, PEG 400, PEG 1000, and combination of propylene glycol with PEG 400, were tested for their bactericidal activity. The minimum bactericidal concentration was noted against four standard strains of organisms, i.e. Streptococcus mutans American Type Culture Collection (ATCC) 25175, Streptococcus mutans ATCC 12598, Enterococcus faecalis ATCC 35550, and Escherichia coli ATCC 25922, using broth dilution assay. Successful endodontic therapy depends upon thorough disinfection of root canals. In some refractory cases, routine endodontic therapy is not sufficient, so intracanal medicaments are used for proper disinfection of canals. Intracanal medicaments are dispensed with vehicles which aid in increased diffusion through the dentinal tubules and improve their efficacy. Among the various vehicles used, glycerine is easily available, whereas others like propylene glycol and polyethylene glycol have to be procured from appropriate sources. Also, these vehicles, being viscous, aid in sustained release of the medicaments and improve their handling properties. The most commonly used intracanal medicaments like calcium hydroxide are ineffective on many microorganisms, while most of the other medicaments like MTAD (Mixture of Tetracycline, an Acid, and a Detergent) and Triple Antibiotic Paste (TAP) consist of antibiotics which can lead to development of antibiotic resistance among microorganisms. Thus, in order to use safer and equally effective intracanal medicaments, newer alternatives like chlorhexidine gluconate, ozonized water, etc., are being explored. Similarly, the five vehicles mentioned above are being tested for their antimicrobial activity in this study. All vehicles exhibited bactericidal activity at

Theoretical insights into the sites and mechanisms for base catalyzed esterification and aldol condensation reactions over Cu.

PubMed

Neurock, Matthew; Tao, Zhiyuan; Chemburkar, Ashwin; Hibbitts, David D; Iglesia, Enrique

2017-04-28

Condensation and esterification are important catalytic routes in the conversion of polyols and oxygenates derived from biomass to fuels and chemical intermediates. Previous experimental studies show that alkanal, alkanol and hydrogen mixtures equilibrate over Cu/SiO 2 and form surface alkoxides and alkanals that subsequently promote condensation and esterification reactions. First-principle density functional theory (DFT) calculations were carried out herein to elucidate the elementary paths and the corresponding energetics for the interconversion of propanal + H 2 to propanol and the subsequent C-C and C-O bond formation paths involved in aldol condensation and esterification of these mixtures over model Cu surfaces. Propanal and hydrogen readily equilibrate with propanol via C-H and O-H addition steps to form surface propoxide intermediates and equilibrated propanal/propanol mixtures. Surface propoxides readily form via low energy paths involving a hydrogen addition to the electrophilic carbon center of the carbonyl of propanal or via a proton transfer from an adsorbed propanol to a vicinal propanal. The resulting propoxide withdraws electron density from the surface and behaves as a base catalyzing the activation of propanal and subsequent esterification and condensation reactions. These basic propoxides can readily abstract the acidic C α -H of propanal to produce the CH 3 CH (-) CH 2 O* enolate, thus initiating aldol condensation. The enolate can subsequently react with a second adsorbed propanal to form a C-C bond and a β-alkoxide alkanal intermediate. The β-alkoxide alkanal can subsequently undergo facile hydride transfer to form the 2-formyl-3-pentanone intermediate that decarbonylates to give the 3-pentanone product. Cu is unique in that it rapidly catalyzes the decarbonylation of the C 2n intermediates to form C 2n-1 3-pentanone as the major product with very small yields of C 2n products. This is likely due to the absence of Brønsted acid sites

Rhodium-Catalyzed Asymmetric Conjugate Alkynylation/Aldol Cyclization Cascade for the Formation of α-Propargyl-β-hydroxyketones.

PubMed

Choo, Ken-Loon; Lautens, Mark

2018-03-02

A rhodium-catalyzed conjugate alkynylation/aldol cyclization cascade was developed. Densely functionalized cyclic α-propargyl-β-hydroxyketones were synthesized with simultaneous formation of a C(sp)-C(sp 3 ) bond, a C(sp 3 )-C(sp 3 ) bond, as well as three new contiguous stereocenters. The transformation was achieved with excellent enantio- and diastereoselectivities using BINAP as the ligand. The synthetic utility of the newly installed alkynyl moiety was exhibited by subjecting the products to an array of derivatizations.

A new fatty aldol ester from the aerial part of Mimosa invisa (Mimosaceae).

PubMed

Nana, Frederic; Sandjo, Louis Pergaud; Keumedjio, Felix; Kuete, Victor; Ngadjui, Bonaventure Tchaleu

2012-01-01

A new aldol ester named 17-O-triacontanoylheptadecanal (1) was isolated from the aerial part of Mimosa invisa (Mimosaceae) together with eight known compounds identified as β-sitosterol (2), α-amyrine (3), lupeol (4), 4'-O-methylepinumisoflavone (5), alpinumisoflavone (6), betulinic acid (7), 3-O-β-D-glucopyranoside of sitosterol (8) and epirobinetinidol (9). The structures of compounds were determined on the basis of NMR and mass spectrometry data as well as by comparing the data reported in the literatures. The antimicrobial activities of the crude extract and compounds 1 and 9 were investigated against seven microbial species. The natural products showed moderate activities compared to that of the crude extract.

Initial solubility & density evaluation of Non-Aqueous system of amino acid salts for CO2 capture: potassium prolinate blended with ethanol and ethylene glycol

NASA Astrophysics Data System (ADS)

Murshid, Ghulam; Garg, Sahil

2018-05-01

Amine scrubbing is the state of the art technology for CO2 capture, and solvent selection can significantly reduce the capital and energy cost of the process. Higher energy requirement for aqueous amine based CO2 removal process is still a most important downside preventive its industrial deployment. Therefore, in this study, novel non-aqueous based amino acid salt system consisting of potassium prolinate, ethanol and ethylene glycol has been studied. This work presents initial CO2 solubility study and important physical properties i.e. density of the studied solvent system. Previous work showed that non-aqueous system of potassium prolinate and ethanol has good absorption rates and requires lower energy for solvent regeneration. However, during regeneration, solvent loss issues were found due to lower boiling point of the ethanol. Therefore, ethylene glycol was added into current studied system for enhancing the overall boiling point of the system. The good initial CO2 solubility and low density of studied solvent system offers several advantages as compared to conventional amine solutions.

Compromised redox homeostasis, altered nitroso-redox balance, and therapeutic possibilities in atrial fibrillation.

PubMed

Simon, Jillian N; Ziberna, Klemen; Casadei, Barbara

2016-04-01

Although the initiation, development, and maintenance of atrial fibrillation (AF) have been linked to alterations in myocyte redox state, the field lacks a complete understanding of the impact these changes may have on cellular signalling, atrial electrophysiology, and disease progression. Recent studies demonstrate spatiotemporal changes in reactive oxygen species production shortly after the induction of AF in animal models with an uncoupling of nitric oxide synthase activity ensuing in the presence of long-standing persistent AF, ultimately leading to a major shift in nitroso-redox balance. However, it remains unclear which radical or non-radical species are primarily involved in the underlying mechanisms of AF or which proteins are targeted for redox modification. In most instances, only free radical oxygen species have been assessed; yet evidence from the redox signalling field suggests that non-radical species are more likely to regulate cellular processes. A wider appreciation for the distinction of these species and how both species may be involved in the development and maintenance of AF could impact treatment strategies. In this review, we summarize how redox second-messenger systems are regulated and discuss the recent evidence for alterations in redox regulation in the atrial myocardium in the presence of AF, while identifying some critical missing links. We also examine studies looking at antioxidants for the prevention and treatment of AF and propose alternative redox targets that may serve as superior therapeutic options for the treatment of AF. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

A multi-electron redox mediator for redox-targeting lithium-sulfur flow batteries

NASA Astrophysics Data System (ADS)

Li, Guochun; Yang, Liuqing; Jiang, Xi; Zhang, Tianran; Lin, Haibin; Yao, Qiaofeng; Lee, Jim Yang

2018-02-01

The lithium-sulfur flow battery (LSFB) is a new addition to the rechargeable lithium flow batteries (LFBs) where sulfur or a sulfur compound is used as the cathode material against the lithium anode. We report here our evaluation of an organic sulfide - dimethyl trisulfide (DMTS), as 1) a catholyte of a LFB and 2) a multi-electron redox mediator for discharging and charging a solid sulfur cathode without any conductive additives. The latter configuration is also known as the redox-targeting lithium-sulfur flow battery (RTLSFB). The LFB provides an initial discharge capacity of 131.5 mAh g-1DMTS (1.66 A h L-1), which decreases to 59 mAh g-1DMTS (0.75 A h L-1) after 40 cycles. The RTLSFB delivers a significantly higher application performance - initial discharge capacity of 1225.3 mAh g-1sulfur (3.83 A h L-1), for which 1030.9 mAh g-1sulfur (3.23 A h L-1) is still available after 40 cycles. The significant increase in the discharge and charge duration of the LFB after sulfur addition indicates that DMTS is better used as a redox mediator in a RTLSFB than as a catholyte in a LFB.

Involvement of Redox State in the Aging of Drosophila melanogaster

PubMed Central

Radyuk, Svetlana N.; Sohal, Rajindar S.

2013-01-01

Abstract Significance: The main objective of this review was to provide an exposition of investigations, conducted in Drosophila melanogaster, on the role of reactive oxygen species and redox state in the aging process. While early transgenic studies did not clearly support the validity of the oxidative stress hypothesis of aging, predicated on the accumulation of structural damage, they spawned a broader search for redox-related effects that might impact the aging process. Recent Advances: Initial evidence implicating the thiol redox state as a possible causative factor in aging has been obtained in Drosophila. Overexpression of genes, such as GCL, G6PD, Prx2, and Prx5, which are involved in the maintenance of thiol redox homeostasis, has strong positive effects on longevity. Further, the depletion of peroxiredoxin activity in the mitochondria through the double knockdown of Prx5 and Prx3 not only results in a redox crisis but also elicits a rapid aging phenotype. Critical Issues: Herein, we summarize the present status of knowledge about the main components of the machinery controlling thiol redox homeostasis and describe how age-related redox fluctuations might impact aging more acutely through disruption of the redox-sensitive signaling mechanisms rather than via the simple accumulation of structural damage. Future Directions: Based on these initial insights into the plausible impact of redox fluctuations on redox signaling, future studies should focus on the pathways that have been explicitly implicated in aging, such as insulin signaling, TOR, and JNK/FOXO, with particular attention to elements that are redox sensitive. Antioxid. Redox Signal. 19, 788–803. PMID:23458359

Synthesis and Characterization of Aldol Condensation Products from Unknown Aldehydes and Ketones: An Inquiry-Based Experiment in the Undergraduate Laboratory

ERIC Educational Resources Information Center

Angelo, Nicholas G.; Henchey, Laura K.; Waxman, Adam J.; Canary, James W.; Arora, Paramjit S.; Wink, Donald

2007-01-01

An experiment for the undergraduate chemistry laboratory in which students perform the aldol condensation on an unknown aldehyde and an unknown ketone is described. The experiment involves the use of techniques such as TLC, column chromatography, and recrystallization, and compounds are characterized by [to the first power]H NMR, GC-MS, and FTIR.…

Sequential aldol condensation-transition metal-catalyzed addition reactions of aldehydes, methyl ketones, and arylboronic acids.

PubMed

Liao, Yuan-Xi; Xing, Chun-Hui; Israel, Matthew; Hu, Qiao-Sheng

2011-04-15

Sequential aldol condensation of aldehydes with methyl ketones followed by transition metal-catalyzed addition reactions of arylboronic acids to form β-substituted ketones is described. By using the 1,1'-spirobiindane-7,7'-diol (SPINOL)-based phosphite, an asymmetric version of this type of sequential reaction, with up to 92% ee, was also realized. Our study provided an efficient method to access β-substituted ketones and might lead to the development of other sequential/tandem reactions with transition metal-catalyzed addition reactions as the key step. © 2011 American Chemical Society

40 CFR 721.10518 - Diethylene glycol, polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Diethylene glycol, polymer with... Substances § 721.10518 Diethylene glycol, polymer with diisocyanatoalkane, polyethylene glycol monomethyl... subject to reporting. (1) The chemical substance identified generically as diethylene glycol, polymer with...

Mitochondrial Redox Signaling and Tumor Progression.

PubMed

Chen, Yuxin; Zhang, Haiqing; Zhou, Huanjiao Jenny; Ji, Weidong; Min, Wang

2016-03-25

Cancer cell can reprogram their energy production by switching mitochondrial oxidative phosphorylation to glycolysis. However, mitochondria play multiple roles in cancer cells, including redox regulation, reactive oxygen species (ROS) generation, and apoptotic signaling. Moreover, these mitochondrial roles are integrated via multiple interconnected metabolic and redox sensitive pathways. Interestingly, mitochondrial redox proteins biphasically regulate tumor progression depending on cellular ROS levels. Low level of ROS functions as signaling messengers promoting cancer cell proliferation and cancer invasion. However, anti-cancer drug-initiated stress signaling could induce excessive ROS, which is detrimental to cancer cells. Mitochondrial redox proteins could scavenger basal ROS and function as "tumor suppressors" or prevent excessive ROS to act as "tumor promoter". Paradoxically, excessive ROS often also induce DNA mutations and/or promotes tumor metastasis at various stages of cancer progression. Targeting redox-sensitive pathways and transcriptional factors in the appropriate context offers great promise for cancer prevention and therapy. However, the therapeutics should be cancer-type and stage-dependent.

Safety assessment of propylene glycol, tripropylene glycol, and PPGs as used in cosmetics.

PubMed

Fiume, Monice M; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

2012-01-01

Propylene glycol is an aliphatic alcohol that functions as a skin conditioning agent, viscosity decreasing agent, solvent, and fragrance ingredient in cosmetics. Tripropylene glycol functions as a humectant, antioxidant, and emulsion stabilizer. Polypropylene glycols (PPGs), including PPG-3, PPG-7, PPG-9, PPG-12, PPG-13, PPG-15, PPG-16, PPG-17, PPG-20, PPG-26, PPG-30, PPG-33, PPG-34, PPG-51, PPG-52, and PPG-69, function primarily as skin conditioning agents, with some solvent use. The majority of the safety and toxicity information presented is for propylene glycol (PG). Propylene glycol is generally nontoxic and is noncarcinogenic. Clinical studies demonstrated an absence of dermal sensitization at use concentrations, although concerns about irritation remained. The CIR Expert Panel determined that the available information support the safety of tripropylene glycol as well as all the PPGs. The Expert Panel concluded that PG, tripropylene glycol, and PPGs ≥3 are safe as used in cosmetic formulations when formulated to be nonirritating.

Ethylene glycol blood test

MedlinePlus

... this page: //medlineplus.gov/ency/article/003564.htm Ethylene glycol blood test To use the sharing features ... enable JavaScript. This test measures the level of ethylene glycol in the blood. Ethylene glycol is a ...

Unusual kinetics of poly(ethylene glycol) oxidation with cerium(IV) ions in sulfuric acid medium and implications for copolymer synthesis.

PubMed

Szymański, Jan K; Temprano-Coleto, Fernando; Pérez-Mercader, Juan

2015-03-14

The cerium(IV)-alcohol couple in an acidic medium is an example of a redox system capable of initiating free radical polymerization. When the alcohol has a polymeric nature, the outcome of such a process is a block copolymer, a member of a class of compounds possessing many useful properties. The most common polymer with a terminal -OH group is poly(ethylene glycol) (PEG); however, the detailed mechanism of its reaction with cerium(IV) remains underexplored. In this paper, we report our findings for this reaction based on spectrophotometric measurements and kinetic modeling. We find that both the reaction order and the net rate constant for the oxidation process depend strongly on the nature of the acidic medium used. In order to account for the experimental observations, we postulate that protonation of PEG decreases its affinity for some of the cerium(IV)-sulfate complexes formed in the system.

Tandem Aldol-Michael Reactions in Aqueous Diethylamine Medium: A Greener and Efficient Approach to Bis-Pyrimidine Derivatives

PubMed Central

Al-Majid, Abdullah M.; Barakat, Assem; AL-Najjar, Hany J.; Mabkhot, Yahia N.; Ghabbour, Hazem A.; Fun, Hoong-Kun

2013-01-01

A simple protocol, involving the green synthesis for the construction of novel bis-pyrimidine derivatives, 3a–i and 4a–e are accomplished by the aqueous diethylamine media promoted tandem Aldol-Michael reaction between two molecules of barbituric acid derivatives 1a,b with various aldehydes. This efficient synthetic protocol using an economic and environmentally friendly reaction media with versatility and shorter reaction time provides bis-pyrimidine derivatives with high yields (88%–99%). PMID:24317435

Nitric-glycolic flowsheet reduction/oxidation (redox) model for the defense waste processing facility (DWPF)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jantzen, C. M.; Williams, M. S.; Edwards, T. B.

Control of the REDuction/OXidation (REDOX) state of glasses containing high concentrations of transition metals, such as High Level Waste (HLW) glasses, is critical in order to eliminate processing difficulties caused by overly reduced or overly oxidized melts. Operation of a HLW melter at Fe +2/ΣFe ratios of between 0.09 and 0.33, retains radionuclides in the melt and thus the final glass. Specifically, long-lived radioactive 99Tc species are less volatile in the reduced Tc 4+ state as TcO 2 than as NaTcO 4 or Tc 2O 7, and ruthenium radionuclides in the reduced Ru 4+ state are insoluble RuO 2 inmore » the melt which are not as volatile as NaRuO 4 where the Ru is in the +7 oxidation state. Similarly, hazardous volatile Cr 6+ occurs in oxidized melt pools as Na 2CrO 4 or Na 2Cr 2O 7, while the Cr +3 state is less volatile and remains in the melt as NaCrO 2 or precipitates as chrome rich spinels. The melter REDOX control balances the oxidants and reductants from the feed and from processing additives such as antifoam.« less

[Secondary hyperoxaluria and nephrocalcinosis due to ethylene glycol poisoning].

PubMed

Monet, C; Richard, E; Missonnier, S; Rebouissoux, L; Llanas, B; Harambat, J

2013-08-01

We report the case of a 3-year-old boy admitted to the pediatric emergency department for ethylene glycol poisoning. During hospitalization, he presented dysuria associated with crystalluria. Blood tests showed metabolic acidosis with an elevated anion gap. A renal ultrasound performed a few weeks later revealed bilateral medullary hyperechogenicity. Urine microscopic analysis showed the presence of weddellite crystals. Secondary nephrocalcinosis due to ethylene glycol intoxication was diagnosed. Hyperhydration and crystallization inhibition by magnesium citrate were initiated. Despite this treatment, persistent weddellite crystals and nephrocalcinosis were seen more than 2years after the intoxication. Ethylene glycol is metabolized in the liver by successive oxidations leading to its final metabolite, oxalic acid. Therefore, metabolic acidosis with an elevated anion gap is usually found following ethylene glycol intoxication. Calcium oxalate crystal deposition may occur in several organs, including the kidneys. The precipitation of calcium oxalate in renal tubules can lead to nephrocalcinosis and acute kidney injury. The long-term renal prognosis is related to chronic tubulointerstitial injury caused by nephrocalcinosis. Treatment of ethylene glycol intoxication is based on specific inhibitors of alcohol dehydrogenase and hemodialysis in the most severe forms, and should be started promptly. Copyright © 2013. Published by Elsevier SAS.

Redox Species of Redox Flow Batteries: A Review.

PubMed

Pan, Feng; Wang, Qing

2015-11-18

Due to the capricious nature of renewable energy resources, such as wind and solar, large-scale energy storage devices are increasingly required to make the best use of the renewable power. The redox flow battery is considered suitable for large-scale applications due to its modular design, good scalability and flexible operation. The biggest challenge of the redox flow battery is the low energy density. The redox active species is the most important component in redox flow batteries, and the redox potential and solubility of redox species dictate the system energy density. This review is focused on the recent development of redox species. Different categories of redox species, including simple inorganic ions, metal complexes, metal-free organic compounds, polysulfide/sulfur and lithium storage active materials, are reviewed. The future development of redox species towards higher energy density is also suggested.

Preparation of Low fouling Polyethersulfone Membranes by Simultaneously Phase Separation and Redox Polymerization

NASA Astrophysics Data System (ADS)

Roihatin, A.; Susanto, H.

2017-05-01

This paper presents preparation of low fouling PES membranes by non solvent induced phase separation (NIPS) coupled with redox polymerization. The membrane characterization included water permeability, morphology structure (by SEM) and surface chemistry (by FTIR). Water permeability measurements showed thatthe membranes have water permeability within the range 10-50 L/h.m2.bar. Addition of PEG dan PEGMA intopolymer solution increased water permeability, whereas blending redox initiator and crosslinker, MBAA in polymer solution decreased water permeability. Surface morfology of membranes by SEM showed that unmodified PES membrane had smaller pore size than PEG or PEGMA modified PES membranes. Furthermore, PES-PEG or PES-PEGMA membranes modified by blending with redox initiator and MBAA as crosslinker showed smaller pore size than unmodified membrane. FTIR analysis showed that all membranes have typical spectraof PES polymer; however no additional peak was observed forthe membranes prepared with addition of PEG/PEGMA, initiator redox and also crosslinker. The addition of PEG/PEGMA, redox initiator and crosslinker resulted in membranes with high rejection and an acceptable flux as well as more stable due to relatively high fouling resistance.

Sequential Aldol Condensation – Transition Metal-Catalyzed Addition Reactions of Aldehydes, Methyl Ketones and Arylboronic Acids

PubMed Central

Liao, Yuan-Xi; Xing, Chun-Hui; Israel, Matthew; Hu, Qiao-Sheng

2011-01-01

Sequential aldol condensation of aldehydes with methyl ketones followed by transition metal-catalyzed addition reactions of arylboronic acids to form β-substituted ketones is described. By using the 1,1′-spirobiindane-7,7′-diol (SPINOL)-based phosphite, an asymmetric version of this type of sequential reaction, with up to 92% ee, was also realized. Our study provided an efficient method to access β-substituted ketones and might lead to the development of other sequential/tandem reactions with transition metal-catalyzed addition reactions as the key step. PMID:21417359

Cross-Aldol Reaction of Activated Carbonyls with Nitrosocarbonyl Intermediates: Stereoselective Synthesis toward α-Hydroxy-β-amino Esters and Amides.

PubMed

Mallik, Sumitava; Bhajammanavar, Vinod; Ramakrishna, Isai; Baidya, Mahiuddin

2017-07-21

A practical and flexible strategy toward α-hydroxy-β-amino esters and amides, which are important biological motifs, based on an organocatalytic cross-aldol reaction of in situ-generated nitrosocarbonyl intermediates followed by hydrogenation is presented. The protocol features operational simplicity, high yields, a wide substrate scope, and high regio- and diastereoselectivity profiles. The utility of this method was showcased through the synthesis of bestatin analogues and indole formation.

Microbial Degradation of Propylene Glycol - Modelling Approach of a Batch Experiment

NASA Astrophysics Data System (ADS)

Dathe, Annette; Fernandez, Perrine; Bakken, Lars; Bloem, Esther; French, Helen

2016-04-01

De-icing chemicals are applied in large amounts at airports during winter conditions to keep the runways and aircrafts ice-free. At Gardermoen airport, Norway, most of the applied chemicals can be captured, but about 10 to 20 % infiltrate into the soil along the runways and during take-off. While the commonly used propylene glycol (PG) is easily degradable by local microbial communities, its biological oxygen demand is high, anoxic zones can develop and soluble Fe+2 and Mn+2 ions eventually can reach the groundwater. The objectives of the presented study are to quantify the mechanisms, which control the order of reduction processes in an unsaturated sandy soil, and to test whether measured redox potentials can help to determine underlying biogeochemical reactions. To investigate the mechanisms of microbial degradation, the water phase of soil samples from Gardermoen Airport was replaced by deionized water with 10 mMol PG or 10 mMol glutamate and the samples were incubated at 10°C for about two weeks. The gas phase was sampled and analyzed automatically every three hours. Microbial degradation of the substrate (PG or glutamate) was modelled following a Monod kinetics using the FME (Flexible Modelling Environment) package of R (Project for Statistical Computing). The model was calibrated against measurements of O2 depletion and CO2 production. The initial concentrations of O2, CO2 and PG or glutamate are known and microbial yields and stoichiometric constants can be calculated from the measurements. Parameter values for the initial microbial population size, maximum microbial growth rate, the half saturation constant, and microbial degradation and respiration rates were fitted using the FME package. The model accounts for carbon from the substrate (PG or glutamate) incorporated into the biomass. Results are promising, but because of the large number of parameters needed to fit a Monod kinetics it is challenging to accurately model a whole redox sequence. The

A rapid analysis of plasma/serum ethylene and propylene glycol by headspace gas chromatography.

PubMed

Ehlers, Alexandra; Morris, Cory; Krasowski, Matthew D

2013-12-01

A rapid headspace-gas chromatography (HS-GC) method was developed for the analysis of ethylene glycol and propylene glycol in plasma and serum specimens using 1,3-propanediol as the internal standard. The method employed a single-step derivitization using phenylboronic acid, was linear to 200 mg/dL and had a lower limit of quantitation of 1 mg/dL suitable for clinical analyses. The analytical method described allows for laboratories with HS-GC instrumentation to analyze ethanol, methanol, isopropanol, ethylene glycol, and propylene glycol on a single instrument with rapid switch-over from alcohols to glycols analysis. In addition to the novel HS-GC method, a retrospective analysis of patient specimens containing ethylene glycol and propylene glycol was also described. A total of 36 patients ingested ethylene glycol, including 3 patients who presented with two separate admissions for ethylene glycol toxicity. Laboratory studies on presentation to hospital for these patients showed both osmolal and anion gap in 13 patients, osmolal but not anion gap in 13 patients, anion but not osmolal gap in 8 patients, and 1 patient with neither an osmolal nor anion gap. Acidosis on arterial blood gas was present in 13 cases. Only one fatality was seen; this was a patient with initial serum ethylene glycol concentration of 1282 mg/dL who died on third day of hospitalization. Propylene glycol was common in patients being managed for toxic ingestions, and was often attributed to iatrogenic administration of propylene glycol-containing medications such as activated charcoal and intravenous lorazepam. In six patients, propylene glycol contributed to an abnormally high osmolal gap. The common presence of propylene glycol in hospitalized patients emphasizes the importance of being able to identify both ethylene glycol and propylene glycol by chromatographic methods.

Bacterial Utilization of Ether Glycols

PubMed Central

Fincher, Edward L.; Payne, W. J.

1962-01-01

A soil bacterium capable of using oligo- and polyethylene glycols and ether alcohols as sole sources of carbon for aerobic growth was isolated. The effects of substituent groups added to the ether bonds on the acceptability of the compounds as substrates were studied. Mechanisms for the incorporation of two-carbon compounds were demonstrated by the observation that acetate, glyoxylate, ethylene glycol, and a number of the tricarboxylic acid cycle intermediates served as growth substrates in minimal media. The rate of oxidation of the short-chained ethylene glycols by adapted resting cells varied directly with increasing numbers of two-carbon units in the chains from one to four. The amount of oxygen consumed per carbon atom of oligo- and polyethylene glycols was 100% of theoretical, but only 67% of theoretical for ethylene glycol. Resting cells oxidized oligo- and polyethylene glycols with 2 to 600 two-carbon units in the chains. Longer chained polyethylene glycols (up to 6,000) were oxidized at a very slow rate by these cells. Dehydrogenation of triethylene glycol by adapted cells was observed, coupling the reaction with methylene blue reduction. PMID:13945208

The decay of Redox-stress Response Capacity is a substantive characteristic of aging: Revising the redox theory of aging.

PubMed

Meng, Jiao; Lv, Zhenyu; Qiao, Xinhua; Li, Xiaopeng; Li, Yazi; Zhang, Yuying; Chen, Chang

2017-04-01

Aging is tightly associated with redox events. The free radical theory of aging indicates that redox imbalance may be an important factor in the aging process. Most studies about redox and aging focused on the static status of oxidative stress levels, there has been little research investigating differential responses to redox challenge during aging. In this study, we used Caenorhabditis elegans and human fibroblasts as models to compare differential responses to oxidative stress challenge in young and old individuals. In response to paraquat stress, young individuals generated more ROS and activated signaling pathways including p-ERK, p-AKT and p-AMPKα/β. After the initial response, young individuals then promoted NRF2 translocation and induced additional antioxidant enzymes and higher expression of phase II enzymes, including SOD, CAT, GPX, HO-1, GSTP-1and others, to maintain redox homeostasis. Moreover, young individuals also demonstrated a better ability to degrade damaged proteins by up-regulating the expression of chaperones and improving proteasome activity. Based on these data, we propose a new concept "Redox-stress Response Capacity (RRC)", which suggests cells or organisms are capable of generating dynamic redox responses to activate cellular signaling and maintain cellular homeostasis. The decay of RRC is the substantive characteristic of aging, which gives a new understand of the redox theory of aging. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Dynamic Redox Regulation of IL-4 Signaling.

PubMed

Dwivedi, Gaurav; Gran, Margaret A; Bagchi, Pritha; Kemp, Melissa L

2015-11-01

Quantifying the magnitude and dynamics of protein oxidation during cell signaling is technically challenging. Computational modeling provides tractable, quantitative methods to test hypotheses of redox mechanisms that may be simultaneously operative during signal transduction. The interleukin-4 (IL-4) pathway, which has previously been reported to induce reactive oxygen species and oxidation of PTP1B, may be controlled by several other putative mechanisms of redox regulation; widespread proteomic thiol oxidation observed via 2D redox differential gel electrophoresis upon IL-4 treatment suggests more than one redox-sensitive protein implicated in this pathway. Through computational modeling and a model selection strategy that relied on characteristic STAT6 phosphorylation dynamics of IL-4 signaling, we identified reversible protein tyrosine phosphatase (PTP) oxidation as the primary redox regulatory mechanism in the pathway. A systems-level model of IL-4 signaling was developed that integrates synchronous pan-PTP oxidation with ROS-independent mechanisms. The model quantitatively predicts the dynamics of IL-4 signaling over a broad range of new redox conditions, offers novel hypotheses about regulation of JAK/STAT signaling, and provides a framework for interrogating putative mechanisms involving receptor-initiated oxidation.

Dynamic Redox Regulation of IL-4 Signaling

PubMed Central

Dwivedi, Gaurav; Gran, Margaret A.; Bagchi, Pritha; Kemp, Melissa L.

2015-01-01

Quantifying the magnitude and dynamics of protein oxidation during cell signaling is technically challenging. Computational modeling provides tractable, quantitative methods to test hypotheses of redox mechanisms that may be simultaneously operative during signal transduction. The interleukin-4 (IL-4) pathway, which has previously been reported to induce reactive oxygen species and oxidation of PTP1B, may be controlled by several other putative mechanisms of redox regulation; widespread proteomic thiol oxidation observed via 2D redox differential gel electrophoresis upon IL-4 treatment suggests more than one redox-sensitive protein implicated in this pathway. Through computational modeling and a model selection strategy that relied on characteristic STAT6 phosphorylation dynamics of IL-4 signaling, we identified reversible protein tyrosine phosphatase (PTP) oxidation as the primary redox regulatory mechanism in the pathway. A systems-level model of IL-4 signaling was developed that integrates synchronous pan-PTP oxidation with ROS-independent mechanisms. The model quantitatively predicts the dynamics of IL-4 signaling over a broad range of new redox conditions, offers novel hypotheses about regulation of JAK/STAT signaling, and provides a framework for interrogating putative mechanisms involving receptor-initiated oxidation. PMID:26562652

Five-year review of a UK 24 hour testing service for plasma ethylene glycol and diethylene glycol.

PubMed

Ford, Loretta T; Berg, Jonathan D

2016-07-01

We present a 5-year review of our UK service for plasma ethylene glycol and diethylene glycol determination in cases of acute poisoning. Ethylene glycol and diethylene glycol have been measured on all samples received for screening for toxicity by gas chromatography-flame ionization detection over a five-year period. A detailed audit of the results has been undertaken. In this period, we received 811 requests, 56% were for first-time screening and 44% repeat analysis where a positive sample has already been received. Of the first-time screen samples, 33.5% screened positive for glycol poisoning. The mean positive ethylene glycol concentration was 1204 mg/L (range 31 to 8666 mg/L). Diethylene glycol was present in 14% of ethylene glycol positive samples but never found alone. The data presented here suggest it is not essential to measure diethylene glycol since its inclusion is rarely likely to change patient management. © The Author(s) 2015.

Central role of the flowering repressor ZCCT2 in the redox control of freezing tolerance and the initial development of flower primordia in wheat

PubMed Central

2014-01-01

Background As both abiotic stress response and development are under redox control, it was hypothesised that the pharmacological modification of the redox environment would affect the initial development of flower primordia and freezing tolerance in wheat (Triticum aestivum L.). Results Pharmacologically induced redox changes were monitored in winter (T. ae. ssp. aestivum cv. Cheyenne, Ch) and spring (T. ae. ssp. spelta; Tsp) wheat genotypes grown after germination at 20/17°C for 9 d (chemical treatment: last 3 d), then at 5°C for 21 d (chemical treatment: first 4 d) and subsequently at 20/17°C for 21 d (recovery period). Thiols and their disulphide forms were measured and based on these data reduction potentials were calculated. In the freezing-tolerant Ch the chemical treatments generally increased both the amount of thiol disulphides and the reduction potential after 3 days at 20/17°C. In the freezing-sensitive Tsp a similar effect of the chemicals on these parameters was only observed after the continuation of the treatments for 4 days at 5°C. The applied chemicals slightly decreased root fresh weight and increased freezing tolerance in Ch, whereas they increased shoot fresh weight in Tsp after 4 days at 5°C. As shown after the 3-week recovery at 20/17°C, the initial development of flower primordia was accelerated in Tsp, whereas it was not affected by the treatments in Ch. The chemicals differently affected the expression of ZCCT2 and that of several other genes related to freezing tolerance and initial development of flower primordia in Ch and Tsp after 4 d at 5°C. Conclusions Various redox-altering compounds and osmotica had differential effects on glutathione disulphide content and reduction potential, and consequently on the expression of the flowering repressor ZCCT2 in the winter wheat Ch and the spring wheat Tsp. We propose that the higher expression of ZCCT2 in Ch may be associated with activation of genes of cold acclimation and its lower

Central role of the flowering repressor ZCCT2 in the redox control of freezing tolerance and the initial development of flower primordia in wheat.

PubMed

Gulyás, Zsolt; Boldizsár, Akos; Novák, Aliz; Szalai, Gabriella; Pál, Magda; Galiba, Gábor; Kocsy, Gábor

2014-04-07

As both abiotic stress response and development are under redox control, it was hypothesised that the pharmacological modification of the redox environment would affect the initial development of flower primordia and freezing tolerance in wheat (Triticum aestivum L.). Pharmacologically induced redox changes were monitored in winter (T. ae. ssp. aestivum cv. Cheyenne, Ch) and spring (T. ae. ssp. spelta; Tsp) wheat genotypes grown after germination at 20/17°C for 9 d (chemical treatment: last 3 d), then at 5°C for 21 d (chemical treatment: first 4 d) and subsequently at 20/17°C for 21 d (recovery period). Thiols and their disulphide forms were measured and based on these data reduction potentials were calculated. In the freezing-tolerant Ch the chemical treatments generally increased both the amount of thiol disulphides and the reduction potential after 3 days at 20/17°C. In the freezing-sensitive Tsp a similar effect of the chemicals on these parameters was only observed after the continuation of the treatments for 4 days at 5°C. The applied chemicals slightly decreased root fresh weight and increased freezing tolerance in Ch, whereas they increased shoot fresh weight in Tsp after 4 days at 5°C. As shown after the 3-week recovery at 20/17°C, the initial development of flower primordia was accelerated in Tsp, whereas it was not affected by the treatments in Ch. The chemicals differently affected the expression of ZCCT2 and that of several other genes related to freezing tolerance and initial development of flower primordia in Ch and Tsp after 4 d at 5°C. Various redox-altering compounds and osmotica had differential effects on glutathione disulphide content and reduction potential, and consequently on the expression of the flowering repressor ZCCT2 in the winter wheat Ch and the spring wheat Tsp. We propose that the higher expression of ZCCT2 in Ch may be associated with activation of genes of cold acclimation and its lower expression in Tsp with the

Domino-hydroformylation/aldol condensation catalysis: highly selective synthesis of α,β-unsaturated aldehydes from olefins.

PubMed

Fang, Xianjie; Jackstell, Ralf; Franke, Robert; Beller, Matthias

2014-10-06

A general and highly chemo-, regio-, and stereoselective synthesis of α,β-unsaturated aldehydes by a domino hydroformylation/aldol condensation reaction has been developed. A variety of olefins and aromatic aldehydes were efficiently converted into various substituted α,β-unsaturated aldehydes in good to excellent yields in the presence of a rhodium phosphine/acid-base catalyst system. In view of the easy availability of the substrates, the high atom-efficiency, the excellent selectivity, and the mild conditions, this method is expected to complement current methodologies for the preparation of α,β-unsaturated aldehydes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Developmental toxicity and structure/activity correlates of glycols and glycol ethers.

PubMed Central

Johnson, E M; Gabel, B E; Larson, J

1984-01-01

In recent years, the National Toxicology Program (NTP) has selected numerous glycol ethers for testing in routine laboratory mammals to ascertain the magnitude of their ability to injure the conceptus. From the lists available of ongoing and projected NTP test chemicals, a series of glycol ethers was selected for examination in vitro in the hydra assay. Also tested were additional chemicals of similar molecular configuration and/or composition. This short-term screening test placed the 14 glycols and glycol ethers tested into a rank order sequence according to their degree of hazard potential to developmental biology, i.e., their ability to interfere with the developmental events characteristic of all ontogenic systems. They were ranked according to the difference between the lowest dose or concentration overtly toxic to adults (A) and the lowest concentration interfering with development (D) of the artificial embryo of reaggregated adult hydra cells and the A/D ratio. Published data from mammalian studies were available for a few of the test chemicals, and in each instance the hydra assay was in direct agreement with the outcomes reported of the more elaborate and standard animal tests. Ethylene glycol and ethylene glycol monomethyl ether were shown by both standard evaluations in mammals, and by the hydra assay, to disrupt embryos only at or very near to their respective adult toxic doses, whereas the mono-ethyl ether perturbed development at approximately one-fifth of the lowest dose overtly toxic to adults.(ABSTRACT TRUNCATED AT 250 WORDS) Images FIGURE 1. A FIGURE 1. B FIGURE 1. C PMID:6499797

Propylene glycol intoxication in a dog.

PubMed

Claus, Melissa A; Jandrey, Karl E; Poppenga, Robert H

2011-12-01

To describe the clinical course, treatment, and outcome of a dog with propylene glycol intoxication. An adult castrated male Australian cattle dog presented to an emergency clinic for an acute onset of ataxia and disorientation after roaming a construction site unsupervised. He tested positive for ethylene glycol using a point-of-care test kit. Treatment for ethylene glycol intoxication included intermittent intravenous boluses of 20% ethanol and hemodialysis. Predialysis and postdialysis blood samples were submitted to the toxicology lab to assess for both ethylene and propylene glycol. The patient tested negative for ethylene glycol and positive for propylene glycol at 1100 mg/dL predialysis and 23 mg/dL postdialysis. The dog made a full recovery. To the authors' knowledge, this is the first report of documented propylene glycol intoxication in a dog, as well as the first report to describe hemodialysis as treatment for propylene glycol intoxication in a dog. © Veterinary Emergency and Critical Care Society 2011.

Curcumin-loaded redox response of self-assembled micelles for enhanced antitumor and anti-inflammation efficacy.

PubMed

Zhao, Shuang; Ma, Litao; Cao, Chengwen; Yu, Qianqian; Chen, Lanmei; Liu, Jie

2017-01-01

At present, it has become evident that inflammation plays a critical role in tumor growth; meanwhile, chemotherapeutic agents using nanocarriers have been suggested as a promising strategy in cancer treatment. In this study, novel redox-responsive micelles were prepared from monomethoxy-poly(ethylene glycol)-chitosan-S-S-hexadecyl (C 16 -SS-CS-mPEG). These micelles were able to carry and deliver drugs into tumor cells. To serve as a control, monomethoxy-poly(ethylene glycol)-chitosan-C-C-hexadecyl (C 16 -CC-CS-mPEG) was developed in a similar fashion to that used to yield C 16 -CC-CS-mPEG without a redox-responsive disulfide bond. The cellular uptake mechanisms of both micelles were determined. The efficient intracellular drug release from micelles in MCF-7 cells was further confirmed. Results indicated that curcumin (Cur) could rapidly form C 16 -SS-CS-mPEG@ Cur micelles when exposed to reducing agents and efficaciously enhance intracellular accumulation. The cytotoxicity assay demonstrated that C 16 -SS-CS-mPEG@Cur exhibited satisfactory cytotoxicity against MCF-7 cells. Anti-inflammation assay results indicated that C 16 -SS-CS-mPEG@Cur treatment significantly downregulated tumor necrosis factor (TNF-α) expression and showed good anti-inflammatory effects in tumor microenvironment. Most importantly, antitumor effects in vivo showed satisfactory therapeutic effects with C 16 -SS-CS-mPEG@Cur. Hence, C 16 -SS-CS-mPEG@Cur micelles can be useful in tumor therapy.

Curcumin-loaded redox response of self-assembled micelles for enhanced antitumor and anti-inflammation efficacy

PubMed Central

Zhao, Shuang; Ma, Litao; Cao, Chengwen; Yu, Qianqian; Chen, Lanmei; Liu, Jie

2017-01-01

At present, it has become evident that inflammation plays a critical role in tumor growth; meanwhile, chemotherapeutic agents using nanocarriers have been suggested as a promising strategy in cancer treatment. In this study, novel redox-responsive micelles were prepared from monomethoxy-poly(ethylene glycol)-chitosan-S-S-hexadecyl (C16-SS-CS-mPEG). These micelles were able to carry and deliver drugs into tumor cells. To serve as a control, monomethoxy-poly(ethylene glycol)-chitosan-C-C-hexadecyl (C16-CC-CS-mPEG) was developed in a similar fashion to that used to yield C16-CC-CS-mPEG without a redox-responsive disulfide bond. The cellular uptake mechanisms of both micelles were determined. The efficient intracellular drug release from micelles in MCF-7 cells was further confirmed. Results indicated that curcumin (Cur) could rapidly form C16-SS-CS-mPEG@ Cur micelles when exposed to reducing agents and efficaciously enhance intracellular accumulation. The cytotoxicity assay demonstrated that C16-SS-CS-mPEG@Cur exhibited satisfactory cytotoxicity against MCF-7 cells. Anti-inflammation assay results indicated that C16-SS-CS-mPEG@Cur treatment significantly downregulated tumor necrosis factor (TNF-α) expression and showed good anti-inflammatory effects in tumor microenvironment. Most importantly, antitumor effects in vivo showed satisfactory therapeutic effects with C16-SS-CS-mPEG@Cur. Hence, C16-SS-CS-mPEG@Cur micelles can be useful in tumor therapy. PMID:28408820

Enantioselective organocatalytic one-pot amination/aza-Michael/aldol condensation reaction sequence: synthesis of 3-pyrrolines with a quaternary stereocenter.

PubMed

Desmarchelier, Alaric; Coeffard, Vincent; Moreau, Xavier; Greck, Christine

2012-10-08

Primary amine-catalyzed direct conversion of α,α-disubstituted aldehydes into 3-pyrrolines with a quaternary stereocenter is reported. The one-pot enantioselective sequence is based on a α-amination, an aza-Michael addition of hydrazine, an aldol condensation dehydratation and proceeds with good yields and excellent levels of enantioselectivity. Synthetically attractive applications including the formation of aziridinopyrrolidine or epoxypyrrolidine derivatives with good yields and selectivities are also described. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Redox Code

PubMed Central

Jones, Dean P.

2015-01-01

Abstract Significance: The redox code is a set of principles that defines the positioning of the nicotinamide adenine dinucleotide (NAD, NADP) and thiol/disulfide and other redox systems as well as the thiol redox proteome in space and time in biological systems. The code is richly elaborated in an oxygen-dependent life, where activation/deactivation cycles involving O2 and H2O2 contribute to spatiotemporal organization for differentiation, development, and adaptation to the environment. Disruption of this organizational structure during oxidative stress represents a fundamental mechanism in system failure and disease. Recent Advances: Methodology in assessing components of the redox code under physiological conditions has progressed, permitting insight into spatiotemporal organization and allowing for identification of redox partners in redox proteomics and redox metabolomics. Critical Issues: Complexity of redox networks and redox regulation is being revealed step by step, yet much still needs to be learned. Future Directions: Detailed knowledge of the molecular patterns generated from the principles of the redox code under defined physiological or pathological conditions in cells and organs will contribute to understanding the redox component in health and disease. Ultimately, there will be a scientific basis to a modern redox medicine. Antioxid. Redox Signal. 23, 734–746. PMID:25891126

The Redox Code.

PubMed

Jones, Dean P; Sies, Helmut

2015-09-20

The redox code is a set of principles that defines the positioning of the nicotinamide adenine dinucleotide (NAD, NADP) and thiol/disulfide and other redox systems as well as the thiol redox proteome in space and time in biological systems. The code is richly elaborated in an oxygen-dependent life, where activation/deactivation cycles involving O₂ and H₂O₂ contribute to spatiotemporal organization for differentiation, development, and adaptation to the environment. Disruption of this organizational structure during oxidative stress represents a fundamental mechanism in system failure and disease. Methodology in assessing components of the redox code under physiological conditions has progressed, permitting insight into spatiotemporal organization and allowing for identification of redox partners in redox proteomics and redox metabolomics. Complexity of redox networks and redox regulation is being revealed step by step, yet much still needs to be learned. Detailed knowledge of the molecular patterns generated from the principles of the redox code under defined physiological or pathological conditions in cells and organs will contribute to understanding the redox component in health and disease. Ultimately, there will be a scientific basis to a modern redox medicine.

Novel insights into redox system and the mechanism of redox regulation.

PubMed

Wang, Xin; Hai, Chunxu

2016-07-01

In view of the critical role of redox system in numerous physiological and pathophysiological processes, it is important to clearly understand the family members and regulatory mechanism of redox system. In this work, we will systematically review the current data detailing the reactive oxygen species (ROS), enzymatic and non-enzymatic antioxidants and redox sensitive transcription factors and we give a brief description of redox-mediated epigenetic and post-translational regulation. We propose that the redox system functions as a "Redox Chain", consisting of "ROS-generating Enzyme Chain", "Combined Antioxidant Chain" and "Transcription Factor Chain". We suggest that an individualized assessment of the redox status in the body should be conducted for the redox intervention of a patient. The strategy of intervention is to maintain redox homeostasis via either facilitation of ROS signaling or enhancement of antioxidant defense. These findings provide valuable new insights into redox system and open up new paths for the control of redox-related disorders.

21 CFR 172.858 - Propylene glycol alginate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Propylene glycol alginate. 172.858 Section 172.858... Propylene glycol alginate. The food additive propylene glycol alginate (CAS Reg. No. 9005-37-2) may be used... the act: (1) The name of the additive, “propylene glycol alginate” or “propylene glycol ester of...

Divergent Synthesis of Multisubstituted Tetrahydrofurans and Pyrrolidines via Intramolecular Aldol-type Trapping of Onium Ylide Intermediates.

PubMed

Jing, Changcheng; Xing, Dong; Gao, Lixin; Li, Jia; Hu, Wenhao

2015-12-21

This paper reports a divergent strategy for the synthesis of multisubstituted tetrahydrofurans and pyrrolidines, starting from easily accessible β-hydroxyketones or β-aminoketones to react with diazo compounds. Under Rh(II) catalysis, this transformation is proposed to proceed through a metal-carbene-induced oxonium ylide or ammonium ylide formation followed by an intramolecular aldol-type trapping of these active intermediates. A series of highly substituted tetrahydrofurans and pyrrolidines are synthesized in high yields with good to excellent diastereoselectivities. Preliminary biological evaluations revealed that both types of heterocycles show good PTP1B inhibitory activities. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Environmental Redox Potential and Redox Capacity Concepts Using a Simple Polarographic Experiment

NASA Astrophysics Data System (ADS)

Pidello, Alejandro

2003-01-01

The redox status of a system may be analyzed in terms of the redox potential (redox intensity component) and the size of the pool of electrons able to be transferred (redox capacity component). In single chemical systems, both terms are thermodynamically related by means of the Nernst equation, the classical redox equilibrium equation. Consequently, either the redox potential measurement or the redox capacity may be used without distinction to define the redox characteristics of these systems. However, in natural environments, which are a complex mixture of compounds undergoing redox reactions in several stages of nonequilibrium, it is difficult to establish the relationships linking redox potential and redox capacity. In this situation, as suggested by various authors, the complementary use of intensity and capacity measurements improves the characterization of the redox status of these systems. The aim of this laboratory experiment is to enable undergraduate students of applied biology (agronomy, veterinary or environmental sciences) to distinguish clearly between redox potential and redox capacity concepts through concrete results obtained in complex natural system such as soil, and to discuss the ecological significance of both concepts.

Principles in redox signaling: from chemistry to functional significance.

PubMed

Bindoli, Alberto; Rigobello, Maria Pia

2013-05-01

Reactive oxygen and nitrogen species are currently considered not only harmful byproducts of aerobic respiration but also critical mediators of redox signaling. The molecules and the chemical principles sustaining the network of cellular redox regulated processes are described. Special emphasis is placed on hydrogen peroxide (H(2)O(2)), now considered as acting as a second messenger, and on sulfhydryl groups, which are the direct targets of the oxidant signal. Cysteine residues of some proteins, therefore, act as sensors of redox conditions and are oxidized in a reversible reaction. In particular, the formation of sulfenic acid and disulfide, the initial steps of thiol oxidation, are described in detail. The many cell pathways involved in reactive oxygen species formation are reported. Central to redox signaling processes are the glutathione and thioredoxin systems controlling H(2)O(2) levels and, hence, the thiol/disulfide balance. Lastly, some of the most important redox-regulated processes involving specific enzymes and organelles are described. The redox signaling area of research is rapidly expanding, and future work will examine new pathways and clarify their importance in cellular pathophysiology.

Ediacaran Redox Fluctuations

NASA Astrophysics Data System (ADS)

Sahoo, S. K.; Jiang, G.; Planavsky, N. J.; Kendall, B.; Owens, J. D.; Anbar, A. D.; Lyons, T. W.

2013-12-01

Evidence for pervasive oxic conditions, and likely even deep ocean oxygenation has been documented at three intervals in the lower (ca. 632 Ma), middle (ca. 580 Ma) and upper (ca. 551 Ma) Ediacaran. The Doushantuo Formation in South China hosts large enrichments of redox-sensitive trace element (e.g., molybdenum, vanadium and uranium) in anoxic shales, which are indicative of a globally oxic ocean-atmosphere system. However, ocean redox conditions between these periods continue to be a topic of debate and remain elusive. We have found evidence for widespread anoxic conditions through much of the Ediacaran in the deep-water Wuhe section in South China. During most of the Ediacaran-early Cambrian in basinal sections is characterized by Fe speciation data and pyrite morphologies that indicate deposition under euxinic conditions with near-crustal enrichments of redox-sensitive element and positive pyrite-sulfur isotope values, which suggest low levels of marine sulfate and widespread euxinia. Our work reinforces an emerging view that the early Earth, including the Ediacaran, underwent numerous rises and falls in surface oxidation state, rather than a unidirectional rise as originally imagined. The Ediacaran ocean thus experienced repetitive expansion and contraction of marine chalcophilic trace-metal levels that may have had fundamental impact on the slow evolution of early animals and ecosystems. Further, this framework forces us to re-examine the relationship between Neoproterozoic oxygenation and metazoan diversification. Varying redox conditions through the Cryogenian and Ediacaran may help explain molecular clock and biomarker evidence for an early appearance and initial diversification of metazoans but with a delay in the appearance of most major metazoan crown groups until close to Ediacaran-Cambrian boundary.

Tandem catalysis for the production of alkyl lactates from ketohexoses at moderate temperatures

DOE PAGES

Orazov, Marat; Davis, Mark E.

2015-09-08

Retro-aldol reactions have been implicated as the limiting steps in catalytic routes to convert biomass-derived hexoses and pentoses into valuable C2, C3, and C4 products such as glycolic acid, lactic acid, 2-hydroxy-3-butenoic acid, 2,4-dihydroxybutanoic acid, and alkyl esters thereof. Due to a lack of efficient retro-aldol catalysts, most previous investigations of catalytic pathways involving these reactions were conducted at high temperatures (≥160 °C). Here, we report moderate-temperature (around 100 °C) retro-aldol reactions of various hexoses in aqueous and alcoholic media with catalysts traditionally known for their capacity to catalyze 1,2-intramolecular carbon shift (1,2-CS) reactions of aldoses, i.e., various molybdenum oxidemore » and molybdate species, nickel(II) diamine complexes, alkali-exchanged stannosilicate molecular sieves, and amorphous TiO2–SiO2 coprecipitates. Solid Lewis acid cocatalysts that are known to catalyze 1,2-intramolecular hydride shift (1,2-HS) reactions that enable the formation of α-hydroxy carboxylic acids from tetroses, trioses, and glycolaldehyde, but cannot readily catalyze retro-aldol reactions of hexoses and pentoses at these moderate temperatures, are shown to be compatible with the aforementioned retro-aldol catalysts. The combination of a distinct retro-aldol catalyst with a 1,2-HS catalyst enables lactic acid and alkyl lactate formation from ketohexoses at moderate temperatures (around 100 °C), with yields comparable to best-reported chemocatalytic examples at high temperature conditions (≥160 °C). The use of moderate temperatures enables numerous desirable features such as lower pressure and significantly less catalyst deactivation.« less

Redox signaling: An evolution from free radicals to aging.

PubMed

Forman, Henry Jay

2016-08-01

Redox biology has evolved from studies of the pathology that involves oxidants to an understanding of how oxidants participate in normal as well as aberrant signal transduction. Although the concept that signal transduction involved changes in the redox state dates from the 1930s, the modern history of redox biology began with the discovery of superoxide dismutase by McCord and Fridovich. The initial focus was on free radicals and damage of macromolecules, which remains an important topic. But, over time it was realized that hydroperoxides, especially H2O2 produced by NADPH oxidases, and electrophiles derived from lipid peroxidation or metabolism, played essential roles in physiologically relevant signaling. The mechanisms through which H2O2 and other electrophiles signal became an important area of study that provided insight into how these reactive molecules were involved in major signaling pathways and regulation of transcription factors. Thus, the field of redox signaling that is the overlap of signal transduction with redox biology was established. Alterations in redox signaling are observed in aging, but we also now know that redox signaling is essential in physiological homeostasis and that sustained deviation from redox homeostasis results in disease. This is a review of the history of redox biology from a personal perspective of nearly fifty years working in this field that hopefully provides some insights for the reader. Copyright © 2016 Elsevier Inc. All rights reserved.

Oxidation of Ethylene Glycol by a Salt-Requiring Bacterium

PubMed Central

Caskey, William H.; Taber, Willard A.

1981-01-01

Bacterium T-52, cultured on ethylene glycol, readily oxidized glycolate and glyoxylate and exhibited elevated activities of ethylene glycol dehydrogenase and glycolate oxidase. Labeled glyoxylate was identified in reaction mixtures containing [14C]-ethylene glycol, but no glycolate was detected. The most likely pathway of ethylene glycol catabolism by bacterium T-52 is sequential oxidation to glycolate and glyoxylate. PMID:16345810

Information processing through a bio-based redox capacitor: signatures for redox-cycling.

PubMed

Liu, Yi; Kim, Eunkyoung; White, Ian M; Bentley, William E; Payne, Gregory F

2014-08-01

Redox-cycling compounds can significantly impact biological systems and can be responsible for activities that range from pathogen virulence and contaminant toxicities, to therapeutic drug mechanisms. Current methods to identify redox-cycling activities rely on the generation of reactive oxygen species (ROS), and employ enzymatic or chemical methods to detect ROS. Here, we couple the speed and sensitivity of electrochemistry with the molecular-electronic properties of a bio-based redox-capacitor to generate signatures of redox-cycling. The redox capacitor film is electrochemically-fabricated at the electrode surface and is composed of a polysaccharide hydrogel with grafted catechol moieties. This capacitor film is redox-active but non-conducting and can engage diffusible compounds in either oxidative or reductive redox-cycling. Using standard electrochemical mediators ferrocene dimethanol (Fc) and Ru(NH3)6Cl3 (Ru(3+)) as model redox-cyclers, we observed signal amplifications and rectifications that serve as signatures of redox-cycling. Three bio-relevant compounds were then probed for these signatures: (i) ascorbate, a redox-active compound that does not redox-cycle; (ii) pyocyanin, a virulence factor well-known for its reductive redox-cycling; and (iii) acetaminophen, an analgesic that oxidatively redox-cycles but also undergoes conjugation reactions. These studies demonstrate that the redox-capacitor can enlist the capabilities of electrochemistry to generate rapid and sensitive signatures of biologically-relevant chemical activities (i.e., redox-cycling). Published by Elsevier B.V.

The effect of glycerol, propylene glycol and polyethylene glycol 400 on the partition coefficient of benzophenone-3 (oxybenzone).

PubMed

Mbah, C J

2007-01-01

Sunscreen products are widely used to protect the skin from sun-related deleterious effects. The objective of the study was to investigate the potential effect of glycerol, propylene glycol and polyethylene glycol 400 on dermal absorption of oxybenzone by studying their effects on its partition coefficient. The partition coefficient was evaluated in a chloroform-water system at room temperature. It was found that glycerol and propylene glycol decreased the partition coefficient of oxybenzone, while an increase in partition coefficient was observed with polyethylene glycol 400. The findings suggest that polyethylene glycol 400 in contrast to glycerol and propylene glycol has the potential of increasing the vehicle-skin partition coefficient of oxybenzone when cosmetic products containing such an UV absorber are topically applied to the skin.

Severe lactic acidosis after an iatrogenic propylene glycol overdose.

PubMed

Zosel, Amy; Egelhoff, Elizabeth; Heard, Kennon

2010-02-01

Propylene glycol is a diluent found in many intravenous and oral drugs, including phenytoin, diazepam, and lorazepam. Propylene glycol is eliminated from the body by oxidation through alcohol dehydrogenase to form lactic acid. Under normal conditions, the body converts lactate to pyruvate and metabolizes pyruvate through the Krebs cycle. Lactic acidosis has occurred in patients, often those with renal dysfunction, who were receiving prolonged infusions of drugs that contain propylene glycol as a diluent. We describe a 50-year-old man who experienced severe lactic acidosis after receiving an accidental overdose of lorazepam, which contains propylene glycol. The patient was acutely intoxicated, with a serum ethanol concentration of 406 mg/dl. He had choked on a large piece of meat and subsequently experienced pulseless electrical activity with ventricular fibrillation cardiac arrest. He was brought to the emergency department; within 2 hours, he was admitted to the intensive care unit for initiation of the hypothermia protocol. The patient began to experience generalized tonic-clonic seizures 12 hours later, which resolved after several boluses of lorazepam. A lorazepam infusion was started; however, it was inadvertently administered at a rate of 2 mg/minute instead of the standard rate of 2 mg/hour. Ten hours later, the administration error was recognized and the infusion stopped. The patient's peak propylene glycol level was 659 mg/dl, pH 6.9, serum bicarbonate level 5 mEq/L, and lactate level 18.6 mmol/L. Fomepizole was started the next day and was continued until hospital day 3. Continuous renal replacement therapy was started and then replaced with continuous venovenous hemofiltration (CVVH) for the remainder of the hospital stay. The patient's acidosis resolved by day 3, when his propylene glycol level had decreased to 45 mg/dl. Fomepizole was discontinued, but the patient's prognosis was poor (anoxic brain injury); thus care was withdrawn and the patient died

21 CFR 172.858 - Propylene glycol alginate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Propylene glycol alginate. 172.858 Section 172.858... CONSUMPTION Multipurpose Additives § 172.858 Propylene glycol alginate. The food additive propylene glycol... information required by the act: (1) The name of the additive, “propylene glycol alginate” or “propylene...

21 CFR 172.858 - Propylene glycol alginate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Propylene glycol alginate. 172.858 Section 172.858... CONSUMPTION Multipurpose Additives § 172.858 Propylene glycol alginate. The food additive propylene glycol... information required by the act: (1) The name of the additive, “propylene glycol alginate” or “propylene...

Boehmite-An Efficient and Recyclable Acid-Base Bifunctional Catalyst for Aldol Condensation Reaction.

PubMed

Reshma, P C Rajan; Vikneshvaran, Sekar; Velmathi, Sivan

2018-06-01

In this work boehmite was used as an acid-base bifunctional catalyst for aldol condensation reactions of aromatic aldehydes and ketones. The catalyst was prepared by simple sol-gel method using Al(NO3)3·9H2O and NH4OH as precursors. The catalyst has been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), UV-visible spectroscopy (DRS), BET surface area analyses. Boehmite is successfully applied as catalyst for the condensation reaction between 4-nitrobenzaldehyde and acetone as a model substrate giving α, β-unsaturated ketones without any side product. The scope of the reaction is extended for various substituted aldehydes. A probable mechanism has been suggested to explain the cooperative behavior of the acidic and basic sites. The catalyst is environmentally friendly and easily recovered from the reaction mixture. Also the catalyst is reusable up to 3 catalytic cycles.

21 CFR 582.4666 - Propylene glycol.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Propylene glycol. 582.4666 Section 582.4666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance is generally...

21 CFR 582.4666 - Propylene glycol.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Propylene glycol. 582.4666 Section 582.4666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance is generally...

21 CFR 582.4666 - Propylene glycol.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Propylene glycol. 582.4666 Section 582.4666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance is generally...

21 CFR 582.4666 - Propylene glycol.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Propylene glycol. 582.4666 Section 582.4666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance is generally...

21 CFR 582.4666 - Propylene glycol.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Propylene glycol. 582.4666 Section 582.4666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance is generally...

Actively targeted delivery of anticancer drug to tumor cells by redox-responsive star-shaped micelles.

PubMed

Shi, Chunli; Guo, Xing; Qu, Qianqian; Tang, Zhaomin; Wang, Yi; Zhou, Shaobing

2014-10-01

In cancer therapy nanocargos based on star-shaped polymer exhibit unique features such as better stability, smaller size distribution and higher drug capacity in comparison to linear polymeric micelles. In this study, we developed a multifunctional star-shaped micellar system by combination of active targeting ability and redox-responsive behavior. The star-shaped micelles with good stability were self-assembled from four-arm poly(ε-caprolactone)-poly(ethylene glycol) copolymer. The redox-responsive behaviors of these micelles triggered by glutathione were evaluated from the changes of micellar size, morphology and molecular weight. In vitro drug release profiles exhibited that in a stimulated normal physiological environment, the redox-responsive star-shaped micelles could maintain good stability, whereas in a reducing and acid environment similar with that of tumor cells, the encapsulated agent was promptly released. In vitro cellular uptake and subcellular localization of these micelles were further studied with confocal laser scanning microscopy and flow cytometry against the human cervical cancer cell line HeLa. In vivo and ex vivo DOX fluorescence imaging displayed that these FA-functionalized star-shaped micelles possessed much better specificity to target solid tumor. Both the qualitative and quantitative results of the antitumor effect in 4T1 tumor-bearing BALB/c mice demonstrated that these redox-responsive star-shaped micelles have a high therapeutic efficiency to artificial solid tumor. Therefore, the multifunctional star-shaped micelles are a potential platform for targeted anticancer drug delivery. Copyright © 2014 Elsevier Ltd. All rights reserved.

21 CFR 582.1666 - Propylene glycol.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Propylene glycol. 582.1666 Section 582.1666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1666 Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance...

21 CFR 582.1666 - Propylene glycol.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Propylene glycol. 582.1666 Section 582.1666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1666 Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance...

21 CFR 582.1666 - Propylene glycol.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Propylene glycol. 582.1666 Section 582.1666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1666 Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance...

Asymmetric synthesis of α-amino acids via homologation of Ni(II) complexes of glycine Schiff bases. Part 2: aldol, Mannich addition reactions, deracemization and (S) to (R) interconversion of α-amino acids.

PubMed

Sorochinsky, Alexander E; Aceña, José Luis; Moriwaki, Hiroki; Sato, Tatsunori; Soloshonok, Vadim

2013-11-01

This review provides a comprehensive treatment of literature data dealing with asymmetric synthesis of α-amino-β-hydroxy and α,β-diamino acids via homologation of chiral Ni(II) complexes of glycine Schiff bases using aldol and Mannich-type reactions. These reactions proceed with synthetically useful chemical yields and thermodynamically controlled stereoselectivity and allow direct introduction of two stereogenic centers in a single operation with predictable stereochemical outcome. Furthermore, new application of Ni(II) complexes of α-amino acids Schiff bases for deracemization of racemic α-amino acids and (S) to (R) interconversion providing additional synthetic opportunities for preparation of enantiomerically pure α-amino acids, is also reviewed. Origin of observed diastereo-/enantioselectivity in the aldol, Mannich-type and deracemization reactions, generality and limitations of these methodologies are critically discussed.

Relative toxicities of formulated glycol aircraft deicers and pure glycol products to duckweed (Lemna minor)

DOE Office of Scientific and Technical Information (OSTI.GOV)

DuFresne, D.L.; Pillard, D.A.

1995-12-31

Ethylene and propylene glycol deicers are commonly used at airports in the US and other countries to both remove snow and ice from aircraft, and to retard the accumulation of those materials. Snow and ice often pile up at airports during the winter and are then flushed into the storm sewer system during warmer temperatures or rainfall. Some of this water containing deicers may enter waterbodies without prior treatment, While previous studies have investigated the effects of deicers on aquatic animals and algae, data are not available on the effects on aquatic macrophytes, Glycol deicers were obtained in the formulatedmore » mixtures used on aircraft; pure ethylene and propylene glycol were obtained from Sigma{reg_sign}. Duckweed (Lemna minor) fronds were exposed to various concentrations of pure and formulated glycol mixtures. The number of fronds at test termination and chlorophyll concentration (measured using a spectrophotometer) were the measured endpoints. Based upon glycol concentration, the formulated products were more toxic than the pure material. These results are consistent with results seen in other animal and plant studies.« less

Glycolic acid physical properties and impurities assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambert, D. P.; Pickenheim, B. R.; Bibler, N. E.

This document has been revised due to recent information that the glycolic acid used in Savannah River National Laboratory (SRNL) experiments contains both formaldehyde and methoxyacetic acid. These impurities were in the glycolic acid used in the testing included in this report and in subsequent testing using DuPont (now called Chemours) supplied Technical Grade 70 wt% glycolic acid. However, these impurities were not reported in earlier revisions. Additional data concerning the properties of glycolic acid have also been added to this report. The Defense Waste Processing Facility (DWPF) is planning to implement a nitric-glycolic acid flowsheets to increase attainment tomore » meet closure commitment dates during Sludge Batch 9. In fiscal year 2009, SRNL was requested to determine the physical properties of formic and glycolic acid blends. Blends of formic acid in glycolic acid were prepared and their physical properties tested. Increasing amounts of glycolic acid led to increases in blend density, viscosity and surface tension as compared to the 90 wt% formic acid that is currently used at DWPF. These increases are small, however, and are not expected to present any difficulties in terms of processing. The effect of sulfur impurities in Technical Grade glycolic acid was studied for its impact on DWPF glass quality. While the glycolic acid specification allows for more sulfate than the current formic acid specification, the ultimate impact is expected to be on the order of 0.033 wt% sulfur in glass. Note that lower sulfur content glycolic acid could likely be procured at some increased cost if deemed necessary. A paper study on the effects of radiation on glycolic acid was performed. The analysis indicates that substitution of glycolic acid for formic acid would not increase the radiolytic production rate of H2 and cause an adverse effect in the Slurry Receipt and Adjustment Tank (SRAT) or Slurry Mix Evaporator (SME) process. It has been cited that glycolic acid

Click-PEGylation - A mobility shift approach to assess the redox state of cysteines in candidate proteins.

PubMed

van Leeuwen, Lucie A G; Hinchy, Elizabeth C; Murphy, Michael P; Robb, Ellen L; Cochemé, Helena M

2017-07-01

The redox state of cysteine thiols is critical for protein function. Whereas cysteines play an important role in the maintenance of protein structure through the formation of internal disulfides, their nucleophilic thiol groups can become oxidatively modified in response to diverse redox challenges and thereby function in signalling and antioxidant defences. These oxidative modifications occur in response to a range of agents and stimuli, and can lead to the existence of multiple redox states for a given protein. To assess the role(s) of a protein in redox signalling and antioxidant defence, it is thus vital to be able to assess which of the multiple thiol redox states are present and to investigate how these alter under different conditions. While this can be done by a range of mass spectrometric-based methods, these are time-consuming, costly, and best suited to study abundant proteins or to perform an unbiased proteomic screen. One approach that can facilitate a targeted assessment of candidate proteins, as well as proteins that are low in abundance or proteomically challenging, is by electrophoretic mobility shift assays. Redox-modified cysteine residues are selectively tagged with a large group, such as a polyethylene glycol (PEG) polymer, and then the proteins are separated by electrophoresis followed by immunoblotting, which allows the inference of redox changes based on band shifts. However, the applicability of this method has been impaired by the difficulty of cleanly modifying protein thiols by large PEG reagents. To establish a more robust method for redox-selective PEGylation, we have utilised a Click chemistry approach, where free thiol groups are first labelled with a reagent modified to contain an alkyne moiety, which is subsequently Click-reacted with a PEG molecule containing a complementary azide function. This strategy can be adapted to study reversibly reduced or oxidised cysteines. Separation of the thiol labelling step from the PEG

Ethylene Glycol Adsorption and Reaction over CeOX(111) Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mullins, David R; Chen, Tsung-Liang

2011-01-01

This study reports the interaction of ethylene glycol with well-ordered CeO{sub x}(111) thin film surfaces. Ethylene glycol initially adsorbs on fully oxidized CeO{sub 2}(111) and reduced CeO{sub 2-x}(111) through the formation of one C-O-Ce bond and then forms a second alkoxy bond after annealing. On fully oxidized CeO{sub 2}(111) both recombination of ethylene glycol and water desorption occur at low temperature leaving stable -OCH{sub 2}CH{sub 2}O- (ethylenedioxy) intermediates and oxygen vacancies on the surface. This ethylenedioxy intermediate goes through C-C bond scission to produce formate species which then react to produce CO and CO{sub 2}. The formation of water resultsmore » in the reduction of the ceria. On a reduced CeO{sub 2-x}(111) surface the reaction selectivity shifts toward a dehydration process. The ethylenedioxy intermediate decomposes by breaking a C-O bond and converts into an enolate species. Similar to the reaction of acetaldehyde on reduced CeO{sub 2-x}(111), the enolate reacts to produce acetaldehyde, acetylene, and ethylene. The loss of O from ethylene glycol leads to a small amount of oxidation of the reduced ceria.« less

Ethylene Glycol Adsorption and Reaction over CeOX(111) Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

T Chen; D Mullins

2011-12-31

This study reports the interaction of ethylene glycol with well-ordered CeO{sub x}(111) thin film surfaces. Ethylene glycol initially adsorbs on fully oxidized CeO{sub 2}(111) and reduced CeO{sub 2-x}(111) through the formation of one C-O-Ce bond and then forms a second alkoxy bond after annealing. On fully oxidized CeO{sub 2}(111) both recombination of ethylene glycol and water desorption occur at low temperature leaving stable -OCH{sub 2}CH{sub 2}O- (ethylenedioxy) intermediates and oxygen vacancies on the surface. This ethylenedioxy intermediate goes through C-C bond scission to produce formate species which then react to produce CO and CO{sub 2}. The formation of water resultsmore » in the reduction of the ceria. On a reduced CeO{sub 2-x}(111) surface the reaction selectivity shifts toward a dehydration process. The ethylenedioxy intermediate decomposes by breaking a C-O bond and converts into an enolate species. Similar to the reaction of acetaldehyde on reduced CeO{sub 2-x}(111), the enolate reacts to produce acetaldehyde, acetylene, and ethylene. The loss of O from ethylene glycol leads to a small amount of oxidation of the reduced ceria.« less

Haemoglobinuria caused by propylene glycol in sheep

PubMed Central

Potter, B. J.

1958-01-01

Haemoglobinuria occurred in sheep anaesthetized by an intravenous injection of pentobarbitone sodium containing propylene glycol: an equivalent dose failed to cause haemoglobinuria in rabbits. Intravenous injection of an aqueous solution of 20% propylene glycol caused haemoglobinaemia and haemoglobinuria in sheep. Neither distilled water nor 20% glycerol in water administered under identical conditions produced these effects. Haemoglobinuria occurred on some occasions when an aqueous 20% solution of propylene glycol was administered to sheep after an injection of saline: it never occurred when a solution of 20% propylene glycol prepared with physiological saline was injected. It is suggested that saline may protect against the haemolytic action of propylene glycol in sheep and that propylene glycol should be avoided as a menstruum for pharmaceutical preparations to be used for injection into the blood stream of these animals. PMID:13618540

Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

PubMed Central

Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

2016-01-01

Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V. PMID:27966605

Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

NASA Astrophysics Data System (ADS)

Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

2016-12-01

Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V.

Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility.

PubMed

Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

2016-12-14

Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V.

Lewis base activation of Lewis acids. Vinylogous aldol addition reactions of conjugated N,O-silyl ketene acetals to aldehydes.

PubMed

Denmark, Scott E; Heemstra, John R

2006-02-01

N,O-Silyl dienyl ketene acetals derived from unsaturated morpholine amides have been developed as highly useful reagents for vinylogous aldol addition reactions. In the presence of SiCl4 and the catalytic action of chiral phosphoramide (R,R)-3, N,O-silyl dienyl ketene acetal 8 undergoes high-yielding and highly site-selective addition to a wide variety of aldehydes with excellent enantioselectivity. Of particular note is the high yields and selectivities obtained from aliphatic aldehydes. Low catalyst loadings (2-5 mol %) can be employed. The morpholine amide serves as a useful precursor for further synthetic manipulation.

Metabolic control of redox and redox control of metabolism in plants.

PubMed

Geigenberger, Peter; Fernie, Alisdair R

2014-09-20

Reduction-oxidation (Redox) status operates as a major integrator of subcellular and extracellular metabolism and is simultaneously itself regulated by metabolic processes. Redox status not only dominates cellular metabolism due to the prominence of NAD(H) and NADP(H) couples in myriad metabolic reactions but also acts as an effective signal that informs the cell of the prevailing environmental conditions. After relay of this information, the cell is able to appropriately respond via a range of mechanisms, including directly affecting cellular functioning and reprogramming nuclear gene expression. The facile accession of Arabidopsis knockout mutants alongside the adoption of broad-scale post-genomic approaches, which are able to provide transcriptomic-, proteomic-, and metabolomic-level information alongside traditional biochemical and emerging cell biological techniques, has dramatically advanced our understanding of redox status control. This review summarizes redox status control of metabolism and the metabolic control of redox status at both cellular and subcellular levels. It is becoming apparent that plastid, mitochondria, and peroxisome functions influence a wide range of processes outside of the organelles themselves. While knowledge of the network of metabolic pathways and their intraorganellar redox status regulation has increased in the last years, little is known about the interorganellar redox signals coordinating these networks. A current challenge is, therefore, synthesizing our knowledge and planning experiments that tackle redox status regulation at both inter- and intracellular levels. Emerging tools are enabling ever-increasing spatiotemporal resolution of metabolism and imaging of redox status components. Broader application of these tools will likely greatly enhance our understanding of the interplay of redox status and metabolism as well as elucidating and characterizing signaling features thereof. We propose that such information will enable

Metabolic Control of Redox and Redox Control of Metabolism in Plants

PubMed Central

Fernie, Alisdair R.

2014-01-01

Abstract Significance: Reduction-oxidation (Redox) status operates as a major integrator of subcellular and extracellular metabolism and is simultaneously itself regulated by metabolic processes. Redox status not only dominates cellular metabolism due to the prominence of NAD(H) and NADP(H) couples in myriad metabolic reactions but also acts as an effective signal that informs the cell of the prevailing environmental conditions. After relay of this information, the cell is able to appropriately respond via a range of mechanisms, including directly affecting cellular functioning and reprogramming nuclear gene expression. Recent Advances: The facile accession of Arabidopsis knockout mutants alongside the adoption of broad-scale post-genomic approaches, which are able to provide transcriptomic-, proteomic-, and metabolomic-level information alongside traditional biochemical and emerging cell biological techniques, has dramatically advanced our understanding of redox status control. This review summarizes redox status control of metabolism and the metabolic control of redox status at both cellular and subcellular levels. Critical Issues: It is becoming apparent that plastid, mitochondria, and peroxisome functions influence a wide range of processes outside of the organelles themselves. While knowledge of the network of metabolic pathways and their intraorganellar redox status regulation has increased in the last years, little is known about the interorganellar redox signals coordinating these networks. A current challenge is, therefore, synthesizing our knowledge and planning experiments that tackle redox status regulation at both inter- and intracellular levels. Future Directions: Emerging tools are enabling ever-increasing spatiotemporal resolution of metabolism and imaging of redox status components. Broader application of these tools will likely greatly enhance our understanding of the interplay of redox status and metabolism as well as elucidating and

Propylene Glycol Poisoning From Excess Whiskey Ingestion

PubMed Central

Ku, Kevin; Sue, Gloria R.

2015-01-01

In this report, we describe a case of high anion gap metabolic acidosis with a significant osmolal gap attributed to the ingestion of liquor containing propylene glycol. Recently, several reports have characterized severe lactic acidosis occurring in the setting of iatrogenic unintentional overdosing of medications that use propylene glycol as a diluent, including lorazepam and diazepam. To date, no studies have explored potential effects of excess propylene glycol in the setting of alcohol intoxication. Our patient endorsed drinking large volumes of cinnamon flavored whiskey, which was likely Fireball Cinnamon Whisky. To our knowledge, this is the first case of propylene glycol toxicity from an intentional ingestion of liquor containing propylene glycol. PMID:26904700

N-silyl oxyketene imines are underused yet highly versatile reagents for catalytic asymmetric synthesis

NASA Astrophysics Data System (ADS)

Denmark, Scott E.; Wilson, Tyler W.

2010-11-01

The reactions of acyl anion equivalents (d1 synthons) with carbonyl electrophiles allow for the construction of a wide range of molecules useful for the synthesis of biologically active compounds, natural products and chiral ligands. Despite their utility, significant challenges still exist for developing catalytic, enantioselective variants of these reactions. For example, the asymmetric benzoin process, arguably the most characteristic reaction of d synthetic equivalents, finds no general solution for reactions involving aliphatic acyl anions. In this Article, we introduce a new class of stable, isolable silyl ketene imines derived from protected cyanohydrins. These nucleophiles serve as acyl anion equivalents in Lewis base catalysed aldol addition reactions and allow for the preparation of cross-benzoin and glycolate-aldol products in high yield and with exceptional diastereo- and enantioselectivities.

A positive chemical ionization GC/MS method for the determination of airborne ethylene glycol and propylene glycols in non-occupational environments.

PubMed

Zhu, Jiping; Feng, Yong-Lai; Aikawa, Bio

2004-11-01

An analytical method for ethylene glycol and propylene glycols has been developed for measuring airborne levels of these chemicals in non-occupational environments such as residences and office buildings. The analytes were collected on charcoal tubes, solvent extracted, and analyzed by gas chromatography-mass spectrometry using a positive chemical ionization technique. The method had a method detection limit of 0.07 microg m(-3) for ethylene glycol and 0.03 microg m(-3) for 1,2- and 1,3-propylene glycols, respectively, based on a 1.44 m3 sampling volume. Indoor air samples of several residential homes and other indoor environments have been analyzed. The median concentrations of ethylene glycol and 1,2-propylene glycol in nine residential indoor air samples were 53 microg m(-3) and 13 microg m(-3) respectively with maximum values of 223 microg m(-3) and 25 microg m(-3) detected for ethylene glycol and 1,2-propylene glycol respectively. The concentrations of these two chemicals in one office and two laboratories were at low microg m(-3) levels. The maximum concentration of 1,3-propylene glycol detected in indoor air was 0.1 microg m(-3).

Construction of poly(lactic-co-glycolic acid)/ZnO nanorods/Ag nanoparticles hybrid coating on Ti implants for enhanced antibacterial activity and biocompatibility.

PubMed

Xiang, Yiming; Li, Jun; Liu, Xiangmei; Cui, Zhenduo; Yang, Xianjin; Yeung, K W K; Pan, Haobo; Wu, Shuilin

2017-10-01

Poly(lactic-co-glycolic acid)/Ag/ZnO nanorods coating were successfully prepared on the surface of Ti metallic implants using a hydrothermal method and subsequent spin-coating of mixtures of poly(lactic-co-glycolic acid) and silver nanoparticles. The poly(lactic-co-glycolic acid)/Ag/ZnO nanorods coating exhibited excellent antibacterial efficacy of over 96% against both Staphylococcus aureus and Escherichia coli when the initial content of Ag nanoparticles was over 3wt%. In addition, the release of both silver and zinc could last for over a hundred days due to the enwrapping of poly(lactic-co-glycolic acid). Proliferation of mouse calvarial cells exhibited minimal cytotoxicity on the poly(lactic-co-glycolic acid)/Ag/ZnO coating with an initial content of Ag nanoparticles of 1wt% and 3wt%, while it inhibited cell proliferation once this value was increased to 6wt%. The results revealed that this poly(lactic-co-glycolic acid)/Ag/ZnO composite could provide a long-lasting antibacterial approach and good cytocompatibility, thus exhibiting considerable potential for biomedical application in orthopedic and dental implants with excellent self-antibacterial activity and good biocompatibility. Copyright © 2017 Elsevier B.V. All rights reserved.

Redox-inflammatory synergy in the metabolic syndrome.

PubMed

Bryan, Sean; Baregzay, Boran; Spicer, Drew; Singal, Pawan K; Khaper, Neelam

2013-01-01

Metabolic syndrome (MetS) comprises interrelated disease states including obesity, insulin resistance and type 2 diabetes (T2DM), dyslipidemia, and hypertension. Essential to normal physiological function, and yet massively damaging in excess, oxidative stress and inflammation are pivotal common threads among the pathologies of MetS. Increasing evidence indicates that redox and inflammatory dysregulation parallels the syndrome's physiological, biochemical, and anthropometric features, leading many to consider the pro-oxidative, pro-inflammatory milieu an unofficial criterion in itself. Left unchecked, cross-promotion of oxidative stress and inflammation creates a feed-forward cycle that can initiate and advance disease progression. Such redox-inflammatory integration is evident in the pathogenesis of obesity, insulin resistance and T2DM, atherogenic dyslipidemia, and hypertension, and is thus hypothesized to be the "common soil" from which they develop. The present review highlights the synergistic contributions of redox-inflammatory processes to each of the components of the MetS.

Glycolic acid physical properties and impurities assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambert, D. P.; Pickenheim, B. R.; Hay, M. S.

This document has been revised to add analytical data for fresh, 1 year old, and 4 year old glycolic acid as recommended in Revision 2 of this document. This was needed to understand the concentration of formaldehyde and methoxyacetic acid, impurities present in the glycolic acid used in Savannah River National Laboratory (SRNL) experiments. Based on this information, the concentration of these impurities did not change during storage. These impurities were in the glycolic acid used in the testing included in this report and in subsequent testing using DuPont (now called Chemours) supplied Technical Grade 70 wt% glycolic acid. However,more » these impurities were not reported in the first two versions of this report. The Defense Waste Processing Facility (DWPF) is planning to implement a nitric-glycolic acid flowsheets to increase attainment to meet closure commitment dates during Sludge Batch 9. In fiscal year 2009, SRNL was requested to determine the physical properties of formic and glycolic acid blends.« less

ROS-mediated redox signaling during cell differentiation in plants.

PubMed

Schmidt, Romy; Schippers, Jos H M

2015-08-01

Reactive oxygen species (ROS) have emerged in recent years as important regulators of cell division and differentiation. The cellular redox state has a major impact on cell fate and multicellular organism development. However, the exact molecular mechanisms through which ROS manifest their regulation over cellular development are only starting to be understood in plants. ROS levels are constantly monitored and any change in the redox pool is rapidly sensed and responded upon. Different types of ROS cause specific oxidative modifications, providing the basic characteristics of a signaling molecule. Here we provide an overview of ROS sensors and signaling cascades that regulate transcriptional responses in plants to guide cellular differentiation and organ development. Although several redox sensors and cascades have been identified, they represent only a first glimpse on the impact that redox signaling has on plant development and growth. We provide an initial evaluation of ROS signaling cascades involved in cell differentiation in plants and identify potential avenues for future studies. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation. Copyright © 2015 Elsevier B.V. All rights reserved.

Amplified and in situ detection of redox-active metabolite using a biobased redox capacitor.

PubMed

Kim, Eunkyoung; Gordonov, Tanya; Bentley, William E; Payne, Gregory F

2013-02-19

Redox cycling provides a mechanism to amplify electrochemical signals for analyte detection. Previous studies have shown that diverse mediators/shuttles can engage in redox-cycling reactions with a biobased redox capacitor that is fabricated by grafting redox-active catechols onto a chitosan film. Here, we report that redox cycling with this catechol-chitosan redox capacitor can amplify electrochemical signals for detecting a redox-active bacterial metabolite. Specifically, we studied the redox-active bacterial metabolite pyocyanin that is reported to be a virulence factor and signaling molecule for the opportunistic pathogen P. aeruginosa. We demonstrate that redox cycling can amplify outputs from various electrochemical methods (cyclic voltammetry, chronocoulometry, and differential pulse voltammetry) and can lower the detection limit of pyocyanin to 50 nM. Further, the compatibility of this biobased redox capacitor allows the in situ monitoring of the production of redox-active metabolites (e.g., pyocyanin) during the course of P. aeruginosa cultivation. We anticipate that the amplified output of redox-active virulence factors should permit an earlier detection of life-threatening infections by the opportunistic pathogen P. aeruginosa while the "bio-compatibility" of this measurement approach should facilitate in situ study of the spatiotemporal dynamics of bacterial redox signaling.

40 CFR 721.1729 - Boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Boric acid (H3BO3), mixed esters with... acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol mono Me ether... identified as boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...

40 CFR 721.1729 - Boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Boric acid (H3BO3), mixed esters with... acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol mono Me ether... identified as boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...

40 CFR 721.1729 - Boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Boric acid (H3BO3), mixed esters with... acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol mono Me ether... identified as boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...

40 CFR 721.1729 - Boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Boric acid (H3BO3), mixed esters with... acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol mono Me ether... identified as boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...

40 CFR 721.1729 - Boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Boric acid (H3BO3), mixed esters with... acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol mono Me ether... identified as boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...

The effects of chromium(VI) on the thioredoxin system: Implications for redox regulation

PubMed Central

Myers, Charles R.

2014-01-01

Hexavalent chromium [Cr(VI)] compounds are highly redox active and have long been recognized as potent cytotoxins and carcinogens. The intracellular reduction of Cr(VI) generates reactive Cr intermediates, which are themselves strong oxidants, as well as superoxide, hydrogen peroxide, and hydroxyl radical. These probably contribute to the oxidative damage and effects on redox-sensitive transcription factors that have been reported. However, the identification of events that initiate these signaling changes has been elusive. More recent studies show that Cr(VI) causes irreversible inhibition of thioredoxin reductase (TrxR) and oxidation of thioredoxin (Trx) and peroxiredoxin (Prx). Mitochondrial Trx2/Prx3 are more sensitive to Cr(VI) treatment than cytosolic Trx1/Prx1, although both compartments show thiol oxidation with higher doses or longer treatments. Thiol redox proteomics demonstrate that Trx2, Prx3, and Trx1 are among the most sensitive proteins in cells to Cr(VI) treatment. Their oxidation could therefore represent initiating events that have widespread implications for protein thiol redox control and for multiple aspects of redox signaling. This review summarizes the effects of Cr(VI) on the TrxR/Trx system and how these events could influence a number of downstream redox signaling systems that are influenced by Cr(VI) exposure. Some of the signaling events discussed include the activation of apoptosis signal regulating kinase and MAP kinases (p38 and JNK) and the modulation of a number of redox-sensitive transcription factors including AP-1, NF-κB, p53, and Nrf2. PMID:22542445

Prediction and validation of the duration of hemodialysis sessions for the treatment of acute ethylene glycol poisoning.

PubMed

Iliuta, Ioan-Andrei; Lachance, Philippe; Ghannoum, Marc; Bégin, Yannick; Mac-Way, Fabrice; Desmeules, Simon; De Serres, Sacha A; Julien, Anne-Sophie; Douville, Pierre; Agharazii, Mohsen

2017-08-01

The duration of hemodialysis (HD) sessions for the treatment of acute ethylene glycol poisoning is dependent on concentration, the operational parameters used during HD, and the presence and severity of metabolic acidosis. Ethylene glycol assays are not readily available, potentially leading to undue extension or premature termination of HD. We report a prediction model for the duration of high-efficiency HD sessions based retrospectively on a cohort study of 26 cases of acute ethylene glycol poisoning in 24 individuals treated by alcohol dehydrogenase competitive inhibitors, cofactors and HD. Two patients required HD for more than 14 days, and two died. In 19 cases, the mean ethylene glycol elimination half-life during high-efficiency HD was 165 minutes (95% confidence interval of 151-180 minutes). In a training set of 12 patients with acute ethylene glycol poisoning, using the 90th percentile half-life (195 minutes) and a target ethylene glycol concentration of 2 mmol/l (12.4 mg/dl) allowed all cases to reach a safe ethylene glycol under 3 mmol/l (18.6 mg/dl). The prediction model was then validated in a set of seven acute ethylene glycol poisonings. Thus, the HD session time in hours can be estimated using 4.7 x (Ln [the initial ethylene glycol concentration (mmol/l)/2]), provided that metabolic acidosis is corrected. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

The Redox Proteome*

PubMed Central

Go, Young-Mi; Jones, Dean P.

2013-01-01

The redox proteome consists of reversible and irreversible covalent modifications that link redox metabolism to biologic structure and function. These modifications, especially of Cys, function at the molecular level in protein folding and maturation, catalytic activity, signaling, and macromolecular interactions and at the macroscopic level in control of secretion and cell shape. Interaction of the redox proteome with redox-active chemicals is central to macromolecular structure, regulation, and signaling during the life cycle and has a central role in the tolerance and adaptability to diet and environmental challenges. PMID:23861437

pH and redox-responsive mixed micelles for enhanced intracellular drug release.

PubMed

Cai, Mengtan; Zhu, Kun; Qiu, Yongbin; Liu, Xinrong; Chen, Yuanwei; Luo, Xianglin

2014-04-01

In order to prepare pH and redox sensitive micelles, amphiphilic copolymers of poly (epsilon-caprolactone)-b-poly(2-(diethylamino) ethyl methacrylate) (PCL-PDEA) and disulfide-linked poly(ethyl glycol)-poly(epsilon-caprolactone) (mPEG-SS-PCL) were synthesized. The double-sensitive micelles were prepared simply by solvent-evaporating method with the mixed two copolymers. The pH sensitivity of the mixed micelles was confirmed by the change of micelle diameter/diameter distribution measured by dynamic lighting scattering (DLS) and the redox sensitivity of the mixed micelles was testified by the change of micellar morphous observed by scanning electron microscope (SEM). In vitro drug release showed that drug-loaded mixed micelles (mass ratio 5:5) could achieve above 90% of drug release under low pH and reducing condition within 10h. Moreover, the drug-loaded mixed micelles (mass ratio 5:5) showed the largest cellular toxicity compared with other drug-loaded micelles, while blank mixed micelles exhibited no toxicity. These results meant that the mixed micelles composed by the two amphiphilic copolymers can enhance intracellular drug release. It is concluded that the newly developed mixed micelles can serve as a potential drug delivery system for anticancer drugs. Copyright © 2014 Elsevier B.V. All rights reserved.

Polar stationary phases based on poly(oligo ethylene glycol)diacrylates for capillary gas chromatography

NASA Astrophysics Data System (ADS)

Shiryaeva, V. E.; Popova, T. P.; Korolev, A. A.; Kanat'eva, A. Yu.; Kurganov, A. A.

2017-08-01

New stationary phases for capillary columns in GC are synthesized and studied. The phases are prepared by depositing oligo(ethylene glycol)diacrylates on the column walls and subsequent polymerization (crosslinking) in the presence of peroxide initiators. It is shown that stationary phases based on monomers with molecular weights of 10 kDa or higher exhibit separation properties similar to those of conventional stationary phases based on polyethylene glycol (PEG); however, their thermal stability is higher because they have a higher degree of crosslinking and a more ordered structure of the crosslinked polymers than the respective parameters of phases based on native PEG.

Material compatibility evaluation for DWPF nitric-glycolic acid-literature review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mickalonis, J.; Skidmore, E.

2013-06-01

Glycolic acid is being evaluated as an alternative for formic and nitric acid in the DWPF flowsheet. Demonstration testing and modeling for this new flowsheet has shown that glycolic acid and glycolate has a potential to remain in certain streams generated during the production of the nuclear waste glass. A literature review was conducted to assess the impact of glycolic acid on the corrosion of the materials of construction for the DWPF facility as well as facilities downstream which may have residual glycolic acid and glycolates present. The literature data was limited to solutions containing principally glycolic acid.

The Central Role of Amino Acids in Cancer Redox Homeostasis: Vulnerability Points of the Cancer Redox Code

PubMed Central

Vučetić, Milica; Cormerais, Yann; Parks, Scott K.; Pouysségur, Jacques

2017-01-01

A fine balance in reactive oxygen species (ROS) production and removal is of utmost importance for homeostasis of all cells and especially in highly proliferating cells that encounter increased ROS production due to enhanced metabolism. Consequently, increased production of these highly reactive molecules requires coupling with increased antioxidant defense production within cells. This coupling is observed in cancer cells that allocate significant energy reserves to maintain their intracellular redox balance. Glutathione (GSH), as a first line of defense, represents the most important, non-enzymatic antioxidant component together with the NADPH/NADP+ couple, which ensures the maintenance of the pool of reduced GSH. In this review, the central role of amino acids (AAs) in the maintenance of redox homeostasis in cancer, through GSH synthesis (cysteine, glutamate, and glycine), and nicotinamide adenine dinucleotide (phosphate) production (serine, and glutamine/glutamate) are illustrated. Special emphasis is placed on the importance of AA transporters known to be upregulated in cancers (such as system xc-light chain and alanine-serine-cysteine transporter 2) in the maintenance of AA homeostasis, and thus indirectly, the redox homeostasis of cancer cells. The role of the ROS varies (often described as a “two-edged sword”) during the processes of carcinogenesis, metastasis, and cancer treatment. Therefore, the context-dependent role of specific AAs in the initiation, progression, and dissemination of cancer, as well as in the redox-dependent sensitivity/resistance of the neoplastic cells to chemotherapy are highlighted. PMID:29312889

End-group characterisation of poly(propylene glycol)s by means of electrospray ionisation-tandem mass spectrometry (ESI-MS/MS).

PubMed

Jackson, Anthony T; Slade, Susan E; Thalassinos, Konstantinos; Scrivens, James H

2008-10-01

The end-group functionalisation of a series of poly(propylene glycol)s has been characterised by means of electrospray ionisation-tandem mass spectrometry (ESI-MS/MS). A series of peaks with mass-to-charge ratios that are close to that of the precursor ion were used to generate information on the end-group functionalities of the poly(propylene glycol)s. Fragment ions resulting from losses of both of the end groups were noted from some of the samples. An example is presented of how software can be used to significantly reduce the length of time involved in data interpretation (which is typically the most time-consuming part of the analysis).

Development of a local anesthetic lidocaine-loaded redox-active injectable gel for postoperative pain management.

PubMed

Nagasaki, Yukio; Mizukoshi, Yutaro; Gao, Zhenyu; Feliciano, Chitho P; Chang, Kyungho; Sekiyama, Hiroshi; Kimura, Hiroyuki

2017-07-15

Although local anesthesia is commonly applied for pain relief, there are several issues such as its short duration of action and low effectiveness at the areas of inflammation due to the acidic pH. The presence of excessive amount of reactive oxygen species (ROS) is known to induce inflammation and aggravate pain. To resolve these issues, we developed a redox-active injectable gel (RIG) with ROS-scavenging activity. RIG was prepared by mixing polyamine-b-poly(ethylene glycol)-b-polyamine with nitroxide radical moieties as side chains on the polyamine segments (PMNT-b-PEG-b-PMNT) with a polyanion, which formed a flower-type micelle via electrostatic complexation. Lidocaine could be stably incorporated in its core. When the temperature of the solution was increased to 37°C, the PIC-type flower micelle transformed to gel. The continuous release of lidocaine from the gel was observed for more than three days, without remarkable initial burst, which is probably owing to the stable entrapment of lidocaine in the PIC core of the gel. We evaluated the analgesic effect of RIG in carrageenan-induced arthritis mouse model. Results showed that lidocaine-loaded RIG has stronger and longer analgesic effect when administered in inflamed areas. In contrast, while the use of non-complexed lidocaine did not show analgesic effect one day after its administration. Note that no effect was observed when PIC-type flower micelle without ROS-scavenging ability was used. These findings suggest that local anesthetic-loaded RIG can effectively reduce the number of injection times and limit the side effects associated with the use of anti-inflammatory drugs for postoperative pain management. 1. We have been working on nanomaterials, which effectively eliminate ROS, avoiding dysfunction of mitochondria in healthy cells. 2. We designed redox injectable gel using polyion complexed flower type micelle, which can eliminates ROS locally. 3. We could prepare local anesthesia-loaded redox injectable

Polymeric compositions incorporating polyethylene glycol as a phase change material

DOEpatents

Salyer, Ival O.; Griffen, Charles W.

1989-01-01

A polymeric composition comprising a polymeric material and polyethylene glycol or end-capped polyethylene glycol as a phase change material, said polyethylene glycol and said end-capped polyethylene glycol having a molecular weight greater than about 400 and a heat of fusion greater than about 30 cal/g; the composition is useful in making molded and/or coated materials such as flooring, tiles, wall panels and the like; paints containing polyethylene glycols or end-capped polyethylene glycols are also disclosed.

21 CFR 172.820 - Polyethylene glycol (mean molecular weight 200-9,500).

Code of Federal Regulations, 2011 CFR

2011-04-01

... the total ethylene and diethylene glycol content of polyethylene glycols having mean molecular weights... and diethylene glycol content of polyethylene glycols having mean molecular weights below 450. Analytical Method ethylene glycol and diethylene glycol content of polyethylene glycols The analytical method...

Redox sensor proteins for highly sensitive direct imaging of intracellular redox state.

PubMed

Sugiura, Kazunori; Nagai, Takeharu; Nakano, Masahiro; Ichinose, Hiroshi; Nakabayashi, Takakazu; Ohta, Nobuhiro; Hisabori, Toru

2015-02-13

Intracellular redox state is a critical factor for fundamental cellular functions, including regulation of the activities of various metabolic enzymes as well as ROS production and elimination. Genetically-encoded fluorescent redox sensors, such as roGFP (Hanson, G. T., et al. (2004)) and Redoxfluor (Yano, T., et al. (2010)), have been developed to investigate the redox state of living cells. However, these sensors are not useful in cells that contain, for example, other colored pigments. We therefore intended to obtain simpler redox sensor proteins, and have developed oxidation-sensitive fluorescent proteins called Oba-Q (oxidation balance sensed quenching) proteins. Our sensor proteins derived from CFP and Sirius can be used to monitor the intracellular redox state as their fluorescence is drastically quenched upon oxidation. These blue-shifted spectra of the Oba-Q proteins enable us to monitor various redox states in conjunction with other sensor proteins. Copyright © 2015 Elsevier Inc. All rights reserved.

Redox Regulation of Mitochondrial Function

PubMed Central

Handy, Diane E.

2012-01-01

Abstract Redox-dependent processes influence most cellular functions, such as differentiation, proliferation, and apoptosis. Mitochondria are at the center of these processes, as mitochondria both generate reactive oxygen species (ROS) that drive redox-sensitive events and respond to ROS-mediated changes in the cellular redox state. In this review, we examine the regulation of cellular ROS, their modes of production and removal, and the redox-sensitive targets that are modified by their flux. In particular, we focus on the actions of redox-sensitive targets that alter mitochondrial function and the role of these redox modifications on metabolism, mitochondrial biogenesis, receptor-mediated signaling, and apoptotic pathways. We also consider the role of mitochondria in modulating these pathways, and discuss how redox-dependent events may contribute to pathobiology by altering mitochondrial function. Antioxid. Redox Signal. 16, 1323–1367. PMID:22146081

Material Compatibility Evaluation for DWPF Nitric-Glycolic Acid - Literature Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mickalonis, J. I.; Skidmore, T. E.

Glycolic acid is being evaluated as an alternative for formic and nitric acid in the DWPF flowsheet. Demonstration testing and modeling for this new flowsheet has shown that glycolic acid and glycolate has a potential to remain in certain streams generated during the production of the nuclear waste glass. A literature review was conducted to assess the impact of glycolic acid on the corrosion of the materials of construction for the DWPF facility as well as facilities downstream which may have residual glycolic acid and glycolates present. The literature data was limited to solutions containing principally glycolic acid. The reportedmore » corrosion rates and degradation characteristics have shown the following for the materials of construction.« less

Ethylene glycol

Integrated Risk Information System (IRIS)

Ethylene glycol ; CASRN 107 - 21 - 1 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

Propylene glycol

Integrated Risk Information System (IRIS)

Propylene glycol ; CASRN 57 - 55 - 6 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

Quantitative measures for redox signaling.

PubMed

Pillay, Ché S; Eagling, Beatrice D; Driscoll, Scott R E; Rohwer, Johann M

2016-07-01

Redox signaling is now recognized as an important regulatory mechanism for a number of cellular processes including the antioxidant response, phosphokinase signal transduction and redox metabolism. While there has been considerable progress in identifying the cellular machinery involved in redox signaling, quantitative measures of redox signals have been lacking, limiting efforts aimed at understanding and comparing redox signaling under normoxic and pathogenic conditions. Here we have outlined some of the accepted principles for redox signaling, including the description of hydrogen peroxide as a signaling molecule and the role of kinetics in conferring specificity to these signaling events. Based on these principles, we then develop a working definition for redox signaling and review a number of quantitative methods that have been employed to describe signaling in other systems. Using computational modeling and published data, we show how time- and concentration- dependent analyses, in particular, could be used to quantitatively describe redox signaling and therefore provide important insights into the functional organization of redox networks. Finally, we consider some of the key challenges with implementing these methods. Copyright © 2016 Elsevier Inc. All rights reserved.

Fast determination of ethylene glycol, 1,2-propylene glycol and glycolic acid in blood serum and urine for emergency and clinical toxicology by GC-FID.

PubMed

Hložek, Tomáš; Bursová, Miroslava; Čabalaa, Radomír

2014-12-01

A simple, cost effective, and fast gas chromatography method with flame ionization detection (GC-FID) for simultaneous measurement of ethylene glycol, 1,2-propylene glycol and glycolic acid was developed and validated for clinical toxicology purposes. This new method employs a relatively less used class of derivatization agents - alkyl chloroformates, allowing the efficient and rapid derivatization of carboxylic acids within seconds while glycols are simultaneously derivatized by phenylboronic acid. The entire sample preparation procedure is completed within 10 min. To avoid possible interference from naturally occurring endogenous acids and quantitation errors 3-(4-chlorophenyl) propionic acid was chosen as an internal standard. The significant parameters of the derivatization have been found using chemometric procedures and these parameters were optimized using the face-centered central composite design. The calibration dependence of the method was proved to be quadratic in the range of 50-5000 mg mL(-1), with adequate accuracy (92.4-108.7%) and precision (9.4%). The method was successfully applied to quantify the selected compounds in serum of patients from emergency units. Copyright © 2014 Elsevier B.V. All rights reserved.

Equations for obtaining melting points for the ternary system ethylene glycol/sodium chloride/water and their application to cryopreservation.

PubMed

Woods, E J; Zieger, M A; Gao, D Y; Critser, J K

1999-06-01

The present study describes the H(2)O-NaCl-ethylene glycol ternary system by using a differential scanning calorimeter to measure melting points (T(m)) of four different ratios (R) of ethylene glycol to NaCl and then devising equations to fit the experimental measurements. Ultimately an equation is derived which characterizes the liquidus surface above the eutectic for any R value in the system. This study focuses on ethylene glycol in part because of recent evidence indicating it may be less toxic to pancreatic islets than Me(2)SO, which is currently used routinely for islet cryopreservation. The resulting physical data and previously determined information regarding the osmotic characteristics of canine pancreatic islets are combined in a mathematical model to describe the volumetric response to equilibrium-rate freezing in varying initial concentrations of ethylene glycol. Copyright 1999 Academic Press.

Enantioselective Synthesis of α-Methylene-β-hydroxy Carboxylic Acid Derivatives via a Diastereoselective Aldol-β-Elimination Sequence: Application to the C(15)–C(21) Fragment of Tedanolide C

PubMed Central

Barth, Roland; Roush, William R.

2010-01-01

An enantioselective synthesis of α-methylene-β-hydroxy carboxylic acid derivatives via a highly diastereoselective, one-pot syn-aldol and β-elimination sequence utilizing the chiral β-(phenylselenyl)propionyl imide 15 is described. This new method, which constitutes an alternative to the Baylis-Hillman reaction, has been applied to the synthesis of the C(15)-C(21) fragment of tedanolide C. PMID:20405855

Redox signaling in plants.

PubMed

Foyer, Christine H; Noctor, Graham

2013-06-01

Our aim is to deliver an authoritative and challenging perspective of current concepts in plant redox signaling, focusing particularly on the complex interface between the redox and hormone-signaling pathways that allow precise control of plant growth and defense in response to metabolic triggers and environmental constraints and cues. Plants produce significant amounts of singlet oxygen and other reactive oxygen species (ROS) as a result of photosynthetic electron transport and metabolism. Such pathways contribute to the compartment-specific redox-regulated signaling systems in plant cells that convey information to the nucleus to regulate gene expression. Like the chloroplasts and mitochondria, the apoplast-cell wall compartment makes a significant contribution to the redox signaling network, but unlike these organelles, the apoplast has a low antioxidant-buffering capacity. The respective roles of ROS, low-molecular antioxidants, redox-active proteins, and antioxidant enzymes are considered in relation to the functions of plant hormones such as salicylic acid, jasmonic acid, and auxin, in the composite control of plant growth and defense. Regulation of redox gradients between key compartments in plant cells such as those across the plasma membrane facilitates flexible and multiple faceted opportunities for redox signaling that spans the intracellular and extracellular environments. In conclusion, plants are recognized as masters of the art of redox regulation that use oxidants and antioxidants as flexible integrators of signals from metabolism and the environment.

Redox proteomics for the assessment of redox-related posttranslational regulation in plants.

PubMed

Mock, Hans-Peter; Dietz, Karl-Josef

2016-08-01

The methodological developments of in vivo and in vitro protein labeling and subsequent detection enable sensitive and specific detection of redox modifications. Such methods are presently applied to diverse cells and tissues, subproteomes and developmental as well as environmental conditions. The chloroplast proteome is particularly suitable for such kind of studies, because redox regulation of chloroplast proteins is well established, many plastid proteins are abundant, redox network components have been inventoried in great depth, and functional consequences explored. Thus the repertoire of redox-related posttranslational modifications on the one hand side and their abundance on the other pose a challenge for the near future to understand their contribution to physiological regulation. The various posttranslational redox modifications are introduced, followed by a description of the available proteomics methods. The significance of the redox-related posttranslational modification is exemplarily worked out using established examples from photosynthesis. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock. Copyright © 2016. Published by Elsevier B.V.

FeS/S/FeS(2) redox system and its oxidoreductase-like chemistry in the iron-sulfur world.

PubMed

Wang, Wei; Yang, Bin; Qu, Youpeng; Liu, Xiaoyang; Su, Wenhui

2011-06-01

The iron-sulfur world (ISW) theory is an intriguing prediction regarding the origin of life on early Earth. It hypothesizes that life arose as a geochemical process from inorganic starting materials on the surface of sulfide minerals in the vicinity of deep-sea hot springs. During the last two decades, many experimental studies have been carried out on this topic, and some interesting results have been achieved. Among them, however, the processes of carbon/nitrogen fixation and biomolecular assembly on the mineral surface have received an inordinate amount of attention. To the present, an abiotic model for the oxidation-reduction of intermediates participating in metabolic pathways has been ignored. We examined the oxidation-reduction effect of a prebiotic FeS/S/FeS(2) redox system on the interconversion between several pairs of α-hydroxy acids and α-keto acids (i.e., lactate/pyruvate, malate/oxaloacetate, and glycolate/glyoxylate). We found that, in the absence of FeS, elemental sulfur (S) oxidized α-hydroxy acids to form corresponding keto acids only at a temperature higher than its melting point (113°C); in the presence of FeS, such reactions occurred more efficiently through a coupled reaction mechanism, even at a temperature below the phase transition point of S. On the other hand, FeS was shown to have the capacity to reversibly reduce the keto acids. Such an oxidoreductase-like chemistry of the FeS/S/FeS(2) redox system suggests that it can determine the redox homeostasis of metabolic intermediates in the early evolutionary phase of life. The results provide a possible pathway for the development of primordial redox biochemistry in the iron-sulfur world. Key Words: Iron-sulfur world-FeS/S/FeS(2) redox system-Oxidoreductase-like chemistry. Astrobiology 11, 471-476.

Redox subpopulations and the risk of cancer progression: a new method for characterizing redox heterogeneity

NASA Astrophysics Data System (ADS)

Xu, He N.; Li, Lin Z.

2016-02-01

It has been shown that a malignant tumor is akin to a complex organ comprising of various cell populations including tumor cells that are genetically, metabolically and functionally different. Our redox imaging data have demonstrated intra-tumor redox heterogeneity in all mouse xenografts derived from human melanomas, breast, prostate, and colon cancers. Based on the signals of NADH and oxidized flavoproteins (Fp, including flavin adenine dinucleotide (FAD)) and their ratio, i.e., the redox ratio, which is an indicator of mitochondrial metabolic status, we have discovered several distinct redox subpopulations in xenografts of breast tumors potentially recapitulating functional/metabolic heterogeneity within the tumor. Furthermore, xenografts of breast tumors with higher metastatic potential tend to have a redox subpopulation whose redox ratio is significantly different from that of tumors with lower metastatic potential and usually have a bi-modal distribution of the redox ratio. The redox subpopulations from human breast cancer samples can also be very complex with multiple subpopulations as determined by fitting the redox ratio histograms with multi- Gaussian functions. In this report, we present a new method for identifying the redox subpopulations within individual breast tumor xenografts and human breast tissues, which may be used to differentiate between breast cancer and normal tissue and among breast cancer with different risks of progression.

Development of redox-sensitive red fluorescent proteins for imaging redox dynamics in cellular compartments.

PubMed

Fan, Yichong; Ai, Hui-wang

2016-04-01

We recently reported a redox-sensitive red fluorescent protein, rxRFP1, which is one of the first genetically encoded red-fluorescent probes for general redox states in living cells. As individual cellular compartments have different basal redox potentials, we hereby describe a group of rxRFP1 mutants, showing different midpoint redox potentials for detection of redox dynamics in various subcellular domains, such as mitochondria, the cell nucleus, and endoplasmic reticulum (ER). When these redox probes were expressed and subcellularly localized in human embryonic kidney (HEK) 293 T cells, they responded to membrane-permeable oxidants and reductants. In addition, a mitochondrially localized rxRFP1 mutant, Mito-rxRFP1.1, was used to detect mitochondrial oxidative stress induced by doxorubicin-a widely used cancer chemotherapy drug. Our work has expanded the fluorescent protein toolkit with new research tools for studying compartmentalized redox dynamics and oxidative stress under various pathophysiological conditions.

One-pot aldol condensation and hydrodeoxygenation of biomass-derived carbonyl compounds for biodiesel synthesis.

PubMed

Faba, Laura; Díaz, Eva; Ordóñez, Salvador

2014-10-01

Integrating reaction steps is of key interest in the development of processes for transforming lignocellulosic materials into drop-in fuels. We propose a procedure for performing the aldol condensation (reaction between furfural and acetone is taken as model reaction) and the total hydrodeoxygenation of the resulting condensation adducts in one step, yielding n-alkanes. Different combinations of catalysts (bifunctional catalysts or mechanical mixtures), reaction conditions, and solvents (aqueous and organic) have been tested for performing these reactions in an isothermal batch reactor. The results suggest that the use of bifunctional catalysts and aqueous phase lead to an effective integration of both reactions. Therefore, selectivities to n-alkanes higher than 50% were obtained using this catalyst at typical hydrogenation conditions (T=493 K, P=4.5 MPa, 24 h reaction time). The use of organic solvent, carbonaceous supports, or mechanical mixtures of monofunctional catalysts leads to poorer results owing to side effects; mainly, hydrogenation of reactants and adsorption processes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New insights into redox regulation of stem cell self-renewal and differentiation.

PubMed

Ren, Fenglian; Wang, Kui; Zhang, Tao; Jiang, Jingwen; Nice, Edouard Collins; Huang, Canhua

2015-08-01

Reactive oxygen species (ROS), the natural byproducts of aerobic metabolism, are precisely orchestrated to evoke diverse signaling pathways. To date, studies have focused mainly on the detrimental effects of ROS in stem cells. Recently, accumulating evidence has suggested that ROS also function as second messengers that modulate stem cell self-renewal and differentiation by regulating intricate signaling networks. Although many efforts have been made to clarify the general effects of ROS on signal transduction in stem cells, less is known about the initial and direct executors of ROS signaling, which are known as 'redox sensors'. Modifications of cysteine residues in redox sensors are of significant importance in the modulation of protein function in response to different redox conditions. Intriguingly, most key molecules in ROS signaling and cell cycle regulation (including transcriptional factors and kinases) that are crucial in the regulation of stem cell self-renewal and differentiation have the potential to be redox sensors. We highlight herein the importance of redox regulation of these key regulators in stem cell self-renewal and differentiation. Understanding the mechanisms of redox regulation in stem cell self-renewal and differentiation will open exciting new perspectives for stem cell biology. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation. Copyright © 2015 Elsevier B.V. All rights reserved.

New insights into aldol reactions of methyl isocyanoacetate catalyzed by heterogenized homogeneous catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Rong; Zhao, Jie; Yuan, Bing

The Hayashi–Ito aldol reaction of methyl isocyanoacetate (MI) and benzaldehydes, a classic homogeneous Au(I)-catalyzed reaction, was studied with heterogenized homogeneous catalysts. Among dendrimer encapsulated nanoparticles (NPs) of Au, Pd, Rh, or Pt loaded in mesoporous supports and the homogeneous analogues, the Au NPs led to the highest yield and highest diastereoselectivity of products in toluene at room temperature. The Au catalyst was stable and was recycled for at least six runs without substantial deactivation. Moreover, larger pore sizes of the support and the use of a hydrophobic solvent led to a high selectivity for the trans diastereomer of the product.more » The activation energy is sensitive to neither the size of Au NPs nor the support. A linear Hammett plot was obtained with a positive slope, suggesting an increased electron density on the carbonyl carbon atom in the rate-limiting step. As a result, IR studies revealed a strong interaction between MI and the gold catalyst, supporting the proposed mechanism, in which rate-limiting step involves an electrophilic attack of the aldehyde on the enolate formed from the deprotonated MI.« less

A Simple Organic Microscale Experiment Illustrating the Equilibrium Aspect of the Aldol Condensation

NASA Astrophysics Data System (ADS)

Harrison, Ernest A., Jr.

1998-05-01

A simple microscale experiment has been developed that illustrates the equilibrium aspect of the aldol condensation by using two versions of the standard preparation of tetraphenylcyclopentadienone (5) from benzil (1) and 1,3-diphenyl-2-propanone (2). In version (high base concentration) a mixture of 5 and the diastereomeric 4-hydroxy-2,3,4,5-tetraphenyl-2-cyclopenten-1-ones 3 and 4 are produced, while in the other (low base concentration) a mixture of 1, 2, 3, and 4 results. The experiment is typically carried out in conjunction with the previously reported preparation/dehydration of 3, thus the students provide themselves with authentic samples of 3 and 5. Using these, plus authentic samples of 1 and 2 which are made available, students are able to identify all of the components in the equilibrium mixtures, except 4, by TLC analysis. In the case of 4, students are expected to propose a reasonable structure for this compound based on the observed chemistry and the spectroscopic evidence which is provided (i.e., NMR, IR and mass spectra). The experiment lends itself nicely to either the traditional or problem-solving approach, and it also opens up opportunities for collaborative learning.

Expedient synthesis of C-aryl carbohydrates by consecutive biocatalytic benzoin and aldol reactions.

PubMed

Hernández, Karel; Parella, Teodor; Joglar, Jesús; Bujons, Jordi; Pohl, Martina; Clapés, Pere

2015-02-16

The introduction of aromatic residues connected by a C-C bond into the non-reducing end of carbohydrates is highly significant for the development of innovative structures with improved binding affinity and selectivity (e.g., C-aril-sLex). In this work, an expedient asymmetric "de novo" synthetic route to new aryl carbohydrate derivatives based on two sequential stereoselectively biocatalytic carboligation reactions is presented. First, the benzoin reaction of aromatic aldehydes to dimethoxyacetaldehyde is conducted, catalyzed by benzaldehyde lyase from Pseudomonas fluorescens biovar I. Then, the α-hydroxyketones formed are reduced by using NaBH4 yielding the anti diol. After acetal hydrolysis, the aldol addition of dihydroxyacetone, hydroxyacetone, or glycolaldehyde catalyzed by the stereocomplementary D-fructose-6-phosphate aldolase and L-rhamnulose-1-phosphate aldolase is performed. Both aldolases accept unphosphorylated donor substrates, avoiding the need of handling the phosphate group that the dihydroxyacetone phosphate-dependent aldolases require. In this way, 6-C-aryl-L-sorbose, 6-C-aryl-L-fructose, 6-C-aryl-L-tagatose, and 5-C-aryl-L-xylose derivatives are prepared by using this methodology. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New insights into aldol reactions of methyl isocyanoacetate catalyzed by heterogenized homogeneous catalysts

DOE PAGES

Ye, Rong; Zhao, Jie; Yuan, Bing; ...

2016-12-14

The Hayashi–Ito aldol reaction of methyl isocyanoacetate (MI) and benzaldehydes, a classic homogeneous Au(I)-catalyzed reaction, was studied with heterogenized homogeneous catalysts. Among dendrimer encapsulated nanoparticles (NPs) of Au, Pd, Rh, or Pt loaded in mesoporous supports and the homogeneous analogues, the Au NPs led to the highest yield and highest diastereoselectivity of products in toluene at room temperature. The Au catalyst was stable and was recycled for at least six runs without substantial deactivation. Moreover, larger pore sizes of the support and the use of a hydrophobic solvent led to a high selectivity for the trans diastereomer of the product.more » The activation energy is sensitive to neither the size of Au NPs nor the support. A linear Hammett plot was obtained with a positive slope, suggesting an increased electron density on the carbonyl carbon atom in the rate-limiting step. As a result, IR studies revealed a strong interaction between MI and the gold catalyst, supporting the proposed mechanism, in which rate-limiting step involves an electrophilic attack of the aldehyde on the enolate formed from the deprotonated MI.« less

Engineering Pseudomonas putida KT2440 for Efficient Ethylene Glycol Utilization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beckham, Gregg T; Franden, Mary A; Thelhawadigedara, Lahiru Niroshan Jayakody

Ethylene glycol is used as a raw material in the production of polyethylene terephthalate, in antifreeze, as a gas hydrate inhibitor in pipelines, and for many other industrial applications. It is metabolized by aerobic microbial processes via the highly toxic intermediates glycolaldehyde and glycolate through C2 metabolic pathways. Pseudomonas putida KT2440, which has been engineered for environmental remediation applications given its high toxicity tolerance and broad substrate specificity, is not able to efficiently metabolize ethylene glycol, despite harboring putative genes for this purpose. To further expand the metabolic portfolio of P. putida, we elucidated the metabolic pathway to enable ethylenemore » glycol via systematic overexpression of glyoxylate carboligase (gcl) in combination with other genes. Quantitative reverse transcription polymerase chain reaction demonstrated that all of the four genes in genomic proximity to gcl (hyi, glxR, ttuD, and pykF) are transcribed as an operon. Where the expression of only two genes (gcl and glxR) resulted in growth in ethylene glycol, improved growth and ethylene glycol utilization were observed when the entire gcl operon was expressed. Both glycolaldehyde and glyoxal inhibit growth in concentrations of ethylene glycol above 50 mM. To overcome this bottleneck, the additional overexpression of the glycolate oxidase (glcDEF) operon removes the glycolate bottleneck and minimizes the production of these toxic intermediates, permitting growth in up to 2 M (~124 g/L) and complete consumption of 0.5 M (31 g/L) ethylene glycol in shake flask experiments. In addition, the engineered strain enables conversion of ethylene glycol to medium-chain-length polyhydroxyalkanoates (mcl-PHAs). Overall, this study provides a robust P. putida KT2440 strain for ethylene glycol consumption, which will serve as a foundational strain for further biocatalyst development for applications in the remediation of waste polyester plastics and

A pH and redox dual stimuli-responsive poly(amino acid) derivative for controlled drug release.

PubMed

Gong, Chu; Shan, Meng; Li, Bingqiang; Wu, Guolin

2016-10-01

A pH and redox dual stimuli-responsive poly(aspartic acid) derivative for controlled drug release was successfully developed through progressive ring-opening reactions of polysuccinimide (PSI). Polyethylene glycol (PEG) chains were grafted onto the polyaspartamide backbone via redox-responsive disulfide linkages, providing a sheddable shell for the polymeric micelles in a reductive environment. Phenyl groups were introduced into the polyaspartamide backbone via the aminolysis reaction of PSI to serve as the hydrophobic segment of micelles. The polyaspartamide scaffold was also functionalized with N-(3-aminopropyl)-imidazole to obtain the pH-responsiveness manifesting as a swelling of the core of micelles at a low pH. The polymeric micelles with a core-shell nanostructure forming in neutral media exhibited both pH and redox responsive characteristics. Doxorubicin (DOX) as a model drug was encapsulated into the core of micelles through both hydrophobic and π-π interactions between aromatic rings and the DOX-loaded polymeric micelles exhibited accelerated drug release behaviors in an acidic and reductive environment due to the swelling of hydrophobic cores and the shedding of PEG shells. Furthermore, the cytocompability of the polymer and the cytotoxicity of DOX-loaded micelles towards Hela cells under corresponding conditions were evaluated, and the endocytosis of DOX-loaded polymeric micelles and the intracellular drug release from micelles were observed. All obtained data indicated that the micelle was a promising candidate for controlled drug release. Copyright © 2016 Elsevier B.V. All rights reserved.

Redox potential tuning by redox-inactive cations in nature's water oxidizing catalyst and synthetic analogues.

PubMed

Krewald, Vera; Neese, Frank; Pantazis, Dimitrios A

2016-04-28

The redox potential of synthetic oligonuclear transition metal complexes has been shown to correlate with the Lewis acidity of a redox-inactive cation connected to the redox-active transition metals of the cluster via oxo or hydroxo bridges. Such heterometallic clusters are important cofactors in many metalloenzymes, where it is speculated that the redox-inactive constituent ion of the cluster serves to optimize its redox potential for electron transfer or catalysis. A principal example is the oxygen-evolving complex in photosystem II of natural photosynthesis, a Mn4CaO5 cofactor that oxidizes water into dioxygen, protons and electrons. Calcium is critical for catalytic function, but its precise role is not yet established. In analogy to synthetic complexes it has been suggested that Ca(2+) fine-tunes the redox potential of the manganese cluster. Here we evaluate this hypothesis by computing the relative redox potentials of substituted derivatives of the oxygen-evolving complex with the cations Sr(2+), Gd(3+), Cd(2+), Zn(2+), Mg(2+), Sc(3+), Na(+) and Y(3+) for two sequential transitions of its catalytic cycle. The theoretical approach is validated with a series of experimentally well-characterized Mn3AO4 cubane complexes that are structural mimics of the enzymatic cluster. Our results reproduce perfectly the experimentally observed correlation between the redox potential and the Lewis acidities of redox-inactive cations for the synthetic complexes. However, it is conclusively demonstrated that this correlation does not hold for the oxygen evolving complex. In the enzyme the redox potential of the cluster only responds to the charge of the redox-inactive cations and remains otherwise insensitive to their precise identity, precluding redox-tuning of the metal cluster as a primary role for Ca(2+) in biological water oxidation.

T-REX on-demand redox targeting in live cells.

PubMed

Parvez, Saba; Long, Marcus J C; Lin, Hong-Yu; Zhao, Yi; Haegele, Joseph A; Pham, Vanha N; Lee, Dustin K; Aye, Yimon

2016-12-01

This protocol describes targetable reactive electrophiles and oxidants (T-REX)-a live-cell-based tool designed to (i) interrogate the consequences of specific and time-resolved redox events, and (ii) screen for bona fide redox-sensor targets. A small-molecule toolset comprising photocaged precursors to specific reactive redox signals is constructed such that these inert precursors specifically and irreversibly tag any HaloTag-fused protein of interest (POI) in mammalian and Escherichia coli cells. Syntheses of the alkyne-functionalized endogenous reactive signal 4-hydroxynonenal (HNE(alkyne)) and the HaloTag-targetable photocaged precursor to HNE(alkyne) (also known as Ht-PreHNE or HtPHA) are described. Low-energy light prompts photo-uncaging (t 1/2 <1-2 min) and target-specific modification. The targeted modification of the POI enables precisely timed and spatially controlled redox events with no off-target modification. Two independent pathways are described, along with a simple setup to functionally validate known targets or discover novel sensors. T-REX sidesteps mixed responses caused by uncontrolled whole-cell swamping with reactive signals. Modification and downstream response can be analyzed by in-gel fluorescence, proteomics, qRT-PCR, immunofluorescence, fluorescence resonance energy transfer (FRET)-based and dual-luciferase reporters, or flow cytometry assays. T-REX targeting takes 4 h from initial probe treatment. Analysis of targeted redox responses takes an additional 4-24 h, depending on the nature of the pathway and the type of readouts used.

T-REX on-demand redox targeting in live cells

PubMed Central

Parvez, Saba; Long, Marcus J C; Lin, Hong-Yu; Zhao, Yi; Haegele, Joseph A; Pham, Vanha N; Lee, Dustin K; Aye, Yimon

2017-01-01

This protocol describes targetable reactive electrophiles and oxidants (T-REX)—a live-cell-based tool designed to (i) interrogate the consequences of specific and time-resolved redox events, and (ii) screen for bona fide redox-sensor targets. A small-molecule toolset comprising photocaged precursors to specific reactive redox signals is constructed such that these inert precursors specifically and irreversibly tag any HaloTag-fused protein of interest (POI) in mammalian and Escherichia coli cells. Syntheses of the alkyne-functionalized endogenous reactive signal 4-hydroxynonenal (HNE (alkyne)) and the HaloTag-targetable photocaged precursor to HNE (alkyne) (also known as Ht-PreHNE or HtPHA) are described. Low-energy light prompts photo-uncaging (t1/2 <1–2 min) and target-specific modification. The targeted modification of the POI enables precisely timed and spatially controlled redox events with no off-target modification. Two independent pathways are described, along with a simple setup to functionally validate known targets or discover novel sensors. T-REX sidesteps mixed responses caused by uncontrolled whole-cell swamping with reactive signals. Modification and downstream response can be analyzed by in-gel fluorescence, proteomics, qRT-PCR, immunofluorescence, fluorescence resonance energy transfer (FRET)-based and dual-luciferase reporters, or flow cytometry assays. T-REX targeting takes 4 h from initial probe treatment. Analysis of targeted redox responses takes an additional 4–24 h, depending on the nature of the pathway and the type of readouts used. PMID:27809314

Redox biology of the intestine

PubMed Central

Circu, Magdalena L.; Aw, Tak Yee

2011-01-01

The intestinal tract, known for its capability for self-renew, represents the first barrier of defense between the organism and its luminal environment. The thiol/disulfide redox systems comprising the glutathione/glutathione disulfide (GSH/GSSG), cysteine/cystine (Cys/CySS) and reduced and oxidized thioredoxin (Trx/TrxSS) redox couples play important roles in preserving tissue redox homeostasis, metabolic functions, and cellular integrity. Control of the thiol-disulfide status at the luminal surface is essential for maintaining mucus fluidity and absorption of nutrients, and protection against chemical-induced oxidant injury. Within intestinal cells, these redox couples preserve an environment that supports physiological processes and orchestrates networks of enzymatic reactions against oxidative stress. In this review, we focus on the intestinal redox and antioxidant systems, their subcellular compartmentation, redox signaling and epithelial turnover, and contribution of luminal microbiota, key aspects that are relevant to understanding redox-dependent processes in gut biology with implications for degenerative digestive disorders, such as inflammation and cancer. PMID:21831010

The determination of aluminum, copper, iron, and lead in glycol formulations by atomic absorption spectroscopy

NASA Technical Reports Server (NTRS)

1977-01-01

Initial screening tests and the results obtained in developing procedures to determine Al, Cu, Fe, and Pb in glycol formulations are described. Atomic absorption completion was selected for Cu, Fe and Pb, and after comparison with emission spectroscopy, was selected for Al also. Before completion, carbon, iron, and lead are extracted with diethyl dithio carbamate (DDC) into methyl isobutyl ketone (MIBK). Aluminum was also extracted into MIBK using 8-hydroxyquinoline as a chelating agent. As little as 0.02 mg/l carbon and 0.06 mg/l lead or iron may be determined in glycol formulations. As little as 0.3 mg/l aluminum may be determined.

Ethylene glycol poisoning

MedlinePlus

... Cosmetics Note: This list may not be all-inclusive Symptoms The first symptom of ethylene glycol ingestion ... Toxicology . 3rd ed. New York, NY: McGraw-Hill Education; 2015:chap 33. White SR. Toxic alcohols. In: ...

[Redox Molecular Imaging Using ReMI].

PubMed

Hyodo, Fuminori; Ito, Shinji; Utsumi, Hideo

2015-01-01

Tissue redox status is one of the most important parameters to maintain homeostasis in the living body. Numerous redox reactions are involved in metabolic processes, such as energy production in the mitochondrial electron transfer system. A variety of intracellular molecules such as reactive oxygen species, glutathione, thioredoxins, NADPH, flavins, and ascorbic acid may contribute to the overall redox status in tissues. Breakdown of redox balance may lead to oxidative stress and can induce many pathological conditions such as cancer, neurological disorders, and aging. Therefore imaging of tissue redox status and monitoring antioxidant levels in living organisms can be useful in the diagnosis of disease states and assessment of treatment response. In vivo redox molecular imaging technology such as electron spin resonance imaging (ESRI), magnetic resonance imaging (MRI), and dynamic nuclear polarization (DNP)-MRI (redox molecular imaging; ReMI) is emerging as a viable redox status imaging modality. This review focuses on the application of magnetic resonance technologies using MRI or DNP-MRI and redox-sensitive contrast agents.

Proteomic identification of early salicylate- and flg22-responsive redox-sensitive proteins in Arabidopsis

PubMed Central

Liu, Pei; Zhang, Huoming; Yu, Boying; Xiong, Liming; Xia, Yiji

2015-01-01

Accumulation of reactive oxygen species (ROS) is one of the early defense responses against pathogen infection in plants. The mechanism about the initial and direct regulation of the defense signaling pathway by ROS remains elusive. Perturbation of cellular redox homeostasis by ROS is believed to alter functions of redox-sensitive proteins through their oxidative modifications. Here we report an OxiTRAQ-based proteomic study in identifying proteins whose cysteines underwent oxidative modifications in Arabidopsis cells during the early response to salicylate or flg22, two defense pathway elicitors that are known to disturb cellular redox homeostasis. Among the salicylate- and/or flg22-responsive redox-sensitive proteins are those involved in transcriptional regulation, chromatin remodeling, RNA processing, post-translational modifications, and nucleocytoplasmic shuttling. The identification of the salicylate-/flg22-responsive redox-sensitive proteins provides a foundation from which further study can be conducted toward understanding biological significance of their oxidative modifications during the plant defense response. PMID:25720653

A toxicological review of the propylene glycols.

PubMed

Fowles, Jeff R; Banton, Marcy I; Pottenger, Lynn H

2013-04-01

The toxicological profiles of monopropylene glycol (MPG), dipropylene glycol (DPG), tripropylene glycol (TPG) and polypropylene glycols (PPG; including tetra-rich oligomers) are collectively reviewed, and assessed considering regulatory toxicology endpoints. The review confirms a rich data set for these compounds, covering all of the major toxicological endpoints of interest. The metabolism of these compounds share common pathways, and a consistent profile of toxicity is observed. The common metabolism provides scientific justification for adopting a read-across approach to describing expected hazard potential from data gaps that may exist for specific oligomers. None of the glycols reviewed presented evidence of carcinogenic, mutagenic or reproductive/developmental toxicity potential to humans. The pathologies reported in some animal studies either occurred at doses that exceeded experimental guidelines, or involved mechanisms that are likely irrelevant to human physiology and therefore are not pertinent to the exposures experienced by consumers or workers. At very high chronic doses, MPG causes a transient, slight decrease in hemoglobin in dogs and at somewhat lower doses causes Heinz bodies to form in cats in the absence of any clinical signs of anemia. Some evidence for rare, idiosyncratic skin reactions exists for MPG. However, the larger data set indicates that these compounds have low sensitization potential in animal studies, and therefore are unlikely to represent human allergens. The existing safety evaluations of the FDA, USEPA, NTP and ATSDR for these compounds are consistent and point to the conclusion that the propylene glycols present a very low risk to human health.

Engineering Pseudomonas putida KT2440 for efficient ethylene glycol utilization.

PubMed

Franden, Mary Ann; Jayakody, Lahiru N; Li, Wing-Jin; Wagner, Neil J; Cleveland, Nicholas S; Michener, William E; Hauer, Bernhard; Blank, Lars M; Wierckx, Nick; Klebensberger, Janosch; Beckham, Gregg T

2018-06-07

Ethylene glycol is used as a raw material in the production of polyethylene terephthalate, in antifreeze, as a gas hydrate inhibitor in pipelines, and for many other industrial applications. It is metabolized by aerobic microbial processes via the highly toxic intermediates glycolaldehyde and glycolate through C2 metabolic pathways. Pseudomonas putida KT2440, which has been engineered for environmental remediation applications given its high toxicity tolerance and broad substrate specificity, is not able to efficiently metabolize ethylene glycol, despite harboring putative genes for this purpose. To further expand the metabolic portfolio of P. putida, we elucidated the metabolic pathway to enable ethylene glycol via systematic overexpression of glyoxylate carboligase (gcl) in combination with other genes. Quantitative reverse transcription polymerase chain reaction demonstrated that all of the four genes in genomic proximity to gcl (hyi, glxR, ttuD, and pykF) are transcribed as an operon. Where the expression of only two genes (gcl and glxR) resulted in growth in ethylene glycol, improved growth and ethylene glycol utilization were observed when the entire gcl operon was expressed. Both glycolaldehyde and glyoxal inhibit growth in concentrations of ethylene glycol above 50 mM. To overcome this bottleneck, the additional overexpression of the glycolate oxidase (glcDEF) operon removes the glycolate bottleneck and minimizes the production of these toxic intermediates, permitting growth in up to 2 M (~124 g/L) and complete consumption of 0.5 M (31 g/L) ethylene glycol in shake flask experiments. In addition, the engineered strain enables conversion of ethylene glycol to medium-chain-length polyhydroxyalkanoates (mcl-PHAs). Overall, this study provides a robust P. putida KT2440 strain for ethylene glycol consumption, which will serve as a foundational strain for further biocatalyst development for applications in the remediation of waste polyester plastics and

Sorption interactions between ethylene glycol and carbon nanotubes

NASA Astrophysics Data System (ADS)

Butyrskaya, E. V.; Belyakova, N. V.; Nechaeva, L. S.; Shaposhnik, V. A.; Selemenev, V. F.

2017-03-01

The adsorption of ethylene glycol by carbon nanoparticles is studied. Carbon nanoparticles with the highest affinity to ethylene glycol are identified, and an adsorption isotherm is constructed. Based on quantum chemical calculations of the energies of interaction between the sorbate and nanotubes with (4,4) and (6,6) chirality, a change in mechanism is revealed upon the monomolecular adsorption of ethylene glycol on carbon nanotubes, and the adsorption isotherm is thus interpreted.

Effect of long-term fertilization on humic redox mediators in multiple microbial redox reactions.

PubMed

Guo, Peng; Zhang, Chunfang; Wang, Yi; Yu, Xinwei; Zhang, Zhichao; Zhang, Dongdong

2018-03-01

This study investigated the effects of different long-term fertilizations on humic substances (HSs), humic acids (HAs) and humins, functioning as redox mediators for various microbial redox biotransformations, including 2,2',4,4',5,5'- hexachlorobiphenyl (PCB 153 ) dechlorination, dissimilatory iron reduction, and nitrate reduction, and their electron-mediating natures. The redox activity of HSs for various microbial redox metabolisms was substantially enhanced by long-term application of organic fertilizer (pig manure). As a redox mediator, only humin extracted from soils with organic fertilizer amendment (OF-HM) maintained microbial PCB 153 dechlorination activity (1.03 μM PCB 153 removal), and corresponding HA (OF-HA) most effectively enhanced iron reduction and nitrate reduction by Shewanella putrefaciens. Electrochemical analysis confirmed the enhancement of their electron transfer capacity and redox properties. Fourier transform infrared analysis showed that C=C and C=O bonds, and carboxylic or phenolic groups in HSs might be the redox functional groups affected by fertilization. This research enhances our understanding of the influence of anthropogenic fertility on the biogeochemical cycling of elements and in situ remediation ability in agroecosystems through microorganisms' metabolisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Redox conditions and the efficiency of chlorinated ethene biodegradation: Field studies

USGS Publications Warehouse

Chapelle, F.H.; Bradley, P.M.

2000-01-01

The effect of redox conditions on the efficiency of chlorinated ethene biodegradation was investigated at two field sites. One site (NAS Cecil Field, FL) is characterized by predominantly Fe(III)-reducing conditions in the contaminant source area, grading to predominantly sulfate- reducing conditions downgradient. This sequence of redox conditions led to relatively inefficient biodegradation of chlorinated ethenes, with high concentrations of trichloroethene extending more than 400 meters downgradient of the source area. In contrast, a second site (NBS Kings Bay, GA) characterized by predominantly sulfate-reducing conditions in the source area followed by Fe(III)-reducing conditions downgradient. In this system perchloroethene (PCE) and TCE were rapidly biodegraded and extended less than 100 meters downgradient. Rates of ground- water transport are similar at the two sites (???0.2 m/d) indicating that the succession of redox processes, rather than other hydrologic factors, is the principal control on biodegradation. In particular, redox conditions that favor the initial reduction of highly chlorinated ethenes (methanogenic or sulfate-reducing conditions) followed by more oxidizing conditions (Fe(III)- reducing or oxic conditions) favors efficient biodegradation. Thus, documenting the succession of redox processes is an important step in understanding the efficiency of chlorinated ethene biodegradation in ground-water systems.

REDOX IMAGING OF THE p53-DEPENDENT MITOCHONDRIAL REDOX STATE IN COLON CANCER EX VIVO

PubMed Central

XU, HE N.; FENG, MIN; MOON, LILY; DOLLOFF, NATHAN; EL-DEIRY, WAFIK; LI, LIN Z.

2015-01-01

The mitochondrial redox state and its heterogeneity of colon cancer at tissue level have not been previously reported. Nor has how p53 regulates mitochondrial respiration been measured at (deep) tissue level, presumably due to the unavailability of the technology that has sufficient spatial resolution and tissue penetration depth. Our prior work demonstrated that the mitochondrial redox state and its intratumor heterogeneity is associated with cancer aggressiveness in human melanoma and breast cancer in mouse models, with the more metastatic tumors exhibiting localized regions of more oxidized redox state. Using the Chance redox scanner with an in-plane spatial resolution of 200 μm, we imaged the mitochondrial redox state of the wild-type p53 colon tumors (HCT116 p53 wt) and the p53-deleted colon tumors (HCT116 p53−/−) by collecting the fluorescence signals of nicotinamide adenine dinucleotide (NADH) and oxidized flavoproteins [Fp, including flavin adenine dinucleotide (FAD)] from the mouse xenografts snap-frozen at low temperature. Our results show that: (1) both tumor lines have significant degree of intratumor heterogeneity of the redox state, typically exhibiting a distinct bi-modal distribution that either correlates with the spatial core–rim pattern or the “hot/cold” oxidation-reduction patches; (2) the p53−/− group is significantly more heterogeneous in the mitochondrial redox state and has a more oxidized tumor core compared to the p53 wt group when the tumor sizes of the two groups are matched; (3) the tumor size dependence of the redox indices (such as Fp and Fp redox ratio) is significant in the p53−/− group with the larger ones being more oxidized and more heterogeneous in their redox state, particularly more oxidized in the tumor central regions; (4) the H&E staining images of tumor sections grossly correlate with the redox images. The present work is the first to reveal at the submillimeter scale the intratumor heterogeneity pattern

FeS/S/FeS2 Redox System and Its Oxidoreductase-like Chemistry in the Iron-Sulfur World

NASA Astrophysics Data System (ADS)

Wang, Wei; Yang, Bin; Qu, Youpeng; Liu, Xiaoyang; Su, Wenhui

2011-06-01

The iron-sulfur world (ISW) theory is an intriguing prediction regarding the origin of life on early Earth. It hypothesizes that life arose as a geochemical process from inorganic starting materials on the surface of sulfide minerals in the vicinity of deep-sea hot springs. During the last two decades, many experimental studies have been carried out on this topic, and some interesting results have been achieved. Among them, however, the processes of carbon/nitrogen fixation and biomolecular assembly on the mineral surface have received an inordinate amount of attention. To the present, an abiotic model for the oxidation-reduction of intermediates participating in metabolic pathways has been ignored. We examined the oxidation-reduction effect of a prebiotic FeS/S/FeS2 redox system on the interconversion between several pairs of ±-hydroxy acids and ±-keto acids (i.e., lactate/pyruvate, malate/oxaloacetate, and glycolate/glyoxylate). We found that, in the absence of FeS, elemental sulfur (S) oxidized ±-hydroxy acids to form corresponding keto acids only at a temperature higher than its melting point (113°C); in the presence of FeS, such reactions occurred more efficiently through a coupled reaction mechanism, even at a temperature below the phase transition point of S. On the other hand, FeS was shown to have the capacity to reversibly reduce the keto acids. Such an oxidoreductase-like chemistry of the FeS/S/FeS2 redox system suggests that it can determine the redox homeostasis of metabolic intermediates in the early evolutionary phase of life. The results provide a possible pathway for the development of primordial redox biochemistry in the iron-sulfur world.

Improvement in Wood Bonding Strength of Poly (Vinyl Acetate-Butyl Acrylate) Emulsion by Controlling the Amount of Redox Initiator

PubMed Central

Zhang, Yun; Pang, Bo; Yang, Sen; Fang, Wei; Yang, Sheng; Yuan, Tong-Qi; Sun, Run-Cang

2018-01-01

Polyvinyl acetate emulsion adhesive has been widely used due to its good bonding performance and environmentally friendly properties. Indeed, the bonding performance can be further improved by copolymerizing with other monomers. In this study, the effect of the adjunction of redox initiator (hydrogen peroxide–tartaric acid, H2O2–TA) on the properties of the poly (vinyl acetate-butyl acrylate) (P (VAc–BA)) emulsion adhesive was investigated. With increasing dosage, the reaction became more complete and the obtained film was more compact, as identified via SEM. The core-shell structure of the emulsion particles was confirmed via TEM. Results indicate that while the initiator content increased from 0.5 to 1.0%, a clearer core-shell structure was obtained and the bonding strength of the plywood improved from 2.34 to 2.97 MPa. With the further incorporation of H2O2–TA (i.e., 1.5%), the bonding performance deteriorated. The optimum wood bonding strength (2.97 MPa) of the prepared P (VAc-BA) emulsion adhesive was even better than that (2.55 MPa) of a commercial PVAc emulsion adhesive, suggesting its potential application for the wood industry. PMID:29316725

Redox Deposition of Nanoscale Metal Oxides on Carbon for Next-Generation Electrochemical Capacitors

DTIC Science & Technology

2013-01-01

Nanoscale Metal Oxides Sassin et al. Redox Deposition Approaches to Nanoscale Coatings of Metal Oxides Manganese Oxides. Permanganate (MnO4 ) is a versa...scalability of the permanganate carbon redox reaction for generating MnOx coatings that store charge.21 The initial study per- formed on planar graphite...the carbon surface from the aqueous permanganate solu- tion (pH∼5),29,35 evidenced by a sharp increase in solution pH and a decrease in solution

Redox Pioneer: Professor Vadim N. Gladyshev.

PubMed

Hatfield, Dolph L

2016-07-01

Professor Vadim N. Gladyshev is recognized here as a Redox Pioneer, because he has published an article on antioxidant/redox biology that has been cited more than 1000 times and 29 articles that have been cited more than 100 times. Gladyshev is world renowned for his characterization of the human selenoproteome encoded by 25 genes, identification of the majority of known selenoprotein genes in the three domains of life, and discoveries related to thiol oxidoreductases and mechanisms of redox control. Gladyshev's first faculty position was in the Department of Biochemistry, the University of Nebraska. There, he was a Charles Bessey Professor and Director of the Redox Biology Center. He then moved to the Department of Medicine at Brigham and Women's Hospital, Harvard Medical School, where he is Professor of Medicine and Director of the Center for Redox Medicine. His discoveries in redox biology relate to selenoenzymes, such as methionine sulfoxide reductases and thioredoxin reductases, and various thiol oxidoreductases. He is responsible for the genome-wide identification of catalytic redox-active cysteines and for advancing our understanding of the general use of cysteines by proteins. In addition, Gladyshev has characterized hydrogen peroxide metabolism and signaling and regulation of protein function by methionine-R-sulfoxidation. He has also made important contributions in the areas of aging and lifespan control and pioneered applications of comparative genomics in redox biology, selenium biology, and aging. Gladyshev's discoveries have had a profound impact on redox biology and the role of redox control in health and disease. He is a true Redox Pioneer. Antioxid. Redox Signal. 25, 1-9.

Impact of Glycolate Anion on Aqueous Corrosion in DWPF and Downstream Facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mickalonis, J.

Glycolic acid is being evaluated as an alternate reductant in the preparation of high level waste for the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS). During processing, the glycolic acid may not be completely consumed with small quantities of the glycolate anion being carried forward to other high level waste (HLW) facilities. The SRS liquid waste contractor requested an assessment of the impact of the glycolate anion on the corrosion of the materials of construction (MoC) throughout the waste processing system since this impact had not been previously evaluated. A literature review revealed that corrosion datamore » were not available for the MoCs in glycolic-bearing solutions applicable to SRS systems. Data on the material compatibility with only glycolic acid or its derivative products were identified; however, data were limited for solutions containing glycolic acid or the glycolate anion. For the proprietary coating systems applied to the DWPF concrete, glycolic acid was deemed compatible since the coatings were resistant to more aggressive chemistries than glycolic acid. Additionally, similar coating resins showed acceptable resistance to glycolic acid.« less

Impact of Glycolate Anion on Aqueous Corrosion in DWPF and Downstream Facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mickalonis, J.

Glycolic acid is being evaluated as an alternate reductant in the preparation of high level waste for the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS). During processing, the glycolic acid may not be completely consumed with small quantities of the glycolate anion being carried forward to other high level waste (HLW) facilities. The SRS liquid waste contractor requested an assessment of the impact of the glycolate anion on the corrosion of the materials of construction (MoC) throughout the waste processing system since this impact had not been previously evaluated. A literature review revealed that corrosion datamore » were not available for the MoCs in glycolic-bearing solutions applicable to SRS systems. Data on the material compatibility with only glycolic acid or its derivative products were identified; however, data were limited for solutions containing glycolic acid or the glycolate anion. For the proprietary coating systems applied to the DWPF concrete, glycolic acid was deemed compatible since the coatings were resistant to more aggressive chemistries than glycolic acid. Additionally similar coating resins showed acceptable resistance to glycolic acid.« less

Peculiar behavior of MWW materials in aldol condensation of furfural and acetone.

PubMed

Kikhtyanin, Oleg; Chlubná, Pavla; Jindrová, Tereza; Kubička, David

2014-07-21

MWW family of different structural types (MCM-22, MCM-49, MCM-56 and MCM-36) was used as catalysts for aldol condensation of furfural and acetone studied in a batch reactor at 100 °C, autogenous pressure and a reaction time of 0-4 h. To establish a relation between physico-chemical and catalytic properties of microporous materials, the samples were characterized by XRD, SEM, N2 adsorption, FTIR and TGA. It was found that the acidic solids possessed appreciable activity in the reaction and resulted in the formation of products of aldehyde-ketone interaction. Surprisingly, MCM-22 and MCM-49, i.e. three-dimensional materials containing internal supercages, exhibited higher activity than two MCM-36 catalysts with two-dimensional character having larger accessible external surface area due to expansion of the interlayer space by swelling and pillaring treatments. Moreover, all MWW family catalysts gave higher conversion than the large-pore zeolite BEA. Nevertheless, furfural conversion decreased rapidly for all the studied materials due to coke formation. Unexpectedly, the deactivation was found to be more severe for MCM-36 catalysts than for MCM-22 and MCM-49, which was attributed to the reaction taking place also in supercages that are protected by 10-ring channels from severe coking. In contrast the cups located on the external surface were coked rapidly.

Redox Pioneer: Professor Vadim N. Gladyshev

PubMed Central

2016-01-01

Abstract Professor Vadim N. Gladyshev is recognized here as a Redox Pioneer, because he has published an article on antioxidant/redox biology that has been cited more than 1000 times and 29 articles that have been cited more than 100 times. Gladyshev is world renowned for his characterization of the human selenoproteome encoded by 25 genes, identification of the majority of known selenoprotein genes in the three domains of life, and discoveries related to thiol oxidoreductases and mechanisms of redox control. Gladyshev's first faculty position was in the Department of Biochemistry, the University of Nebraska. There, he was a Charles Bessey Professor and Director of the Redox Biology Center. He then moved to the Department of Medicine at Brigham and Women's Hospital, Harvard Medical School, where he is Professor of Medicine and Director of the Center for Redox Medicine. His discoveries in redox biology relate to selenoenzymes, such as methionine sulfoxide reductases and thioredoxin reductases, and various thiol oxidoreductases. He is responsible for the genome-wide identification of catalytic redox-active cysteines and for advancing our understanding of the general use of cysteines by proteins. In addition, Gladyshev has characterized hydrogen peroxide metabolism and signaling and regulation of protein function by methionine-R-sulfoxidation. He has also made important contributions in the areas of aging and lifespan control and pioneered applications of comparative genomics in redox biology, selenium biology, and aging. Gladyshev's discoveries have had a profound impact on redox biology and the role of redox control in health and disease. He is a true Redox Pioneer. Antioxid. Redox Signal. 25, 1–9. PMID:26984707

Redox Regulation of Cell Survival

PubMed Central

Trachootham, Dunyaporn; Lu, Weiqin; Ogasawara, Marcia A.; Valle, Nilsa Rivera-Del

2008-01-01

Abstract Reactive oxygen species (ROS) and reactive nitrogen species (RNS) play important roles in regulation of cell survival. In general, moderate levels of ROS/RNS may function as signals to promote cell proliferation and survival, whereas severe increase of ROS/RNS can induce cell death. Under physiologic conditions, the balance between generation and elimination of ROS/RNS maintains the proper function of redox-sensitive signaling proteins. Normally, the redox homeostasis ensures that the cells respond properly to endogenous and exogenous stimuli. However, when the redox homeostasis is disturbed, oxidative stress may lead to aberrant cell death and contribute to disease development. This review focuses on the roles of key transcription factors, signal-transduction pathways, and cell-death regulators in affecting cell survival, and how the redox systems regulate the functions of these molecules. The current understanding of how disturbance in redox homeostasis may affect cell death and contribute to the development of diseases such as cancer and degenerative disorders is reviewed. We also discuss how the basic knowledge on redox regulation of cell survival can be used to develop strategies for the treatment or prevention of those diseases. Antioxid. Redox Signal. 10, 1343–1374. PMID:18522489

21 CFR 500.50 - Propylene glycol in or on cat food.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Propylene glycol in or on cat food. 500.50 Section... Propylene glycol in or on cat food. The Food and Drug Administration has determined that propylene glycol in... determined that this use of propylene glycol is not prior sanctioned. [61 FR 19544, May 2, 1996] ...

21 CFR 500.50 - Propylene glycol in or on cat food.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Propylene glycol in or on cat food. 500.50 Section... Propylene glycol in or on cat food. The Food and Drug Administration has determined that propylene glycol in... determined that this use of propylene glycol is not prior sanctioned. [61 FR 19544, May 2, 1996] ...

21 CFR 500.50 - Propylene glycol in or on cat food.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Propylene glycol in or on cat food. 500.50 Section... Propylene glycol in or on cat food. The Food and Drug Administration has determined that propylene glycol in... determined that this use of propylene glycol is not prior sanctioned. [61 FR 19544, May 2, 1996] ...

21 CFR 172.765 - Succistearin (stearoyl propylene glycol hydrogen succinate).

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Succistearin (stearoyl propylene glycol hydrogen... Other Specific Usage Additives § 172.765 Succistearin (stearoyl propylene glycol hydrogen succinate). The food additive succistearin (stearoyl propylene glycol hydrogen succinate) may be safely used in...

Simulated Waste Testing Of Glycolate Impacts On The 2H-Evaporator System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martino, C. J.

2013-08-13

Glycolic acid is being studied as a total or partial replacement for formic acid in the Defense Waste Processing Facility (DWPF) feed preparation process. After implementation, the recycle stream from DWPF back to the high-level waste tank farm will contain soluble sodium glycolate. Most of the potential impacts of glycolate in the tank farm were addressed via a literature review, but several outstanding issues remained. This report documents the non-radioactive simulant tests impacts of glycolate on storage and evaporation of Savannah River Site high-level waste. The testing for which non-radioactive simulants could be used involved the following: the partitioning ofmore » glycolate into the evaporator condensate, the impacts of glycolate on metal solubility, and the impacts of glycolate on the formation and dissolution of sodium aluminosilicate scale within the evaporator. The following are among the conclusions from this work: Evaporator condensate did not contain appreciable amounts of glycolate anion. Of all tests, the highest glycolate concentration in the evaporator condensate was 0.38 mg/L. A significant portion of the tests had glycolate concentration in the condensate at less than the limit of quantification (0.1 mg/L). At ambient conditions, evaporator testing did not show significant effects of glycolate on the soluble components in the evaporator concentrates. Testing with sodalite solids and silicon containing solutions did not show significant effects of glycolate on sodium aluminosilicate formation or dissolution.« less

Biodegradation of Ethylene Glycol by a Salt-Requiring Bacterium1

PubMed Central

Gonzalez, Carlos F.; Taber, Willard A.; Zeitoun, M. A.

1972-01-01

A gram-negative nonmotile rod which was capable of using 1,2-14C-ethylene glycol as a sole carbon source for growth was isolated from a brine pond, Great Salt Lake, Utah. The bacterium (ATCC 27042) required at least 0.85% NaCl for growth and, although the chloride ion was replaceable by sulfate ion, the sodium ion was not replaceable by potassium ion. The maximal concentration of salt tolerated for growth was approximately 12%. The bacterium was oxidase-negative when N,N-dimethyl-p-phenylenediamine was used and weakly positive when N,N,N′,N′-tetramethyl-p-phenylenediamine was used. It grows on many sugars but does not ferment them, it does not have an exogenous vitamin requirement, and it possesses a guanine plus cytosine ratio of 64.3%. Incorporation of ethylene glycol carbon into cell and respired CO2 was quantitated by use of radioactive ethylene glycol and a force-aerated fermentor. Glucose suppressed ethylene glycol metabolism. Cells grown on ethylene and propylene glycol respired ethylene glycol in a Warburg respirometer more rapidly than cells grown on glucose. Spectrophotometric evidence was obtained for oxidation of glycolate to glyoxylate by a dialyzed cell extract. PMID:4568254

Impact of glycolate anion on aqueous corrosion in DWPF and downstream facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mickalonis, J. I.

2015-12-15

Glycolic acid is being evaluated as an alternate reductant in the preparation of high level waste for the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS). During processing, the glycolic acid may not be completely consumed with small quantities of the glycolate anion being carried forward to other high level waste (HLW) facilities. The impact of the glycolate anion on the corrosion of the materials of construction (MoC) throughout the waste processing system has not been previously evaluated. A literature review had revealed that corrosion data were not available for the MoCs in glycolic-bearing solutions applicable tomore » SRS systems. Data on the material compatibility with only glycolic acid or its derivative products were identified; however, data were limited for solutions containing glycolic acid or the glycolate anion.« less

21 CFR 172.765 - Succistearin (stearoyl propylene glycol hydrogen succinate).

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Succistearin (stearoyl propylene glycol hydrogen succinate). 172.765 Section 172.765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... propylene glycol hydrogen succinate). The food additive succistearin (stearoyl propylene glycol hydrogen...

21 CFR 172.765 - Succistearin (stearoyl propylene glycol hydrogen succinate).

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Succistearin (stearoyl propylene glycol hydrogen succinate). 172.765 Section 172.765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... propylene glycol hydrogen succinate). The food additive succistearin (stearoyl propylene glycol hydrogen...

21 CFR 172.765 - Succistearin (stearoyl propylene glycol hydrogen succinate).

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Succistearin (stearoyl propylene glycol hydrogen succinate). 172.765 Section 172.765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... propylene glycol hydrogen succinate). The food additive succistearin (stearoyl propylene glycol hydrogen...

FERMENTATION OF ETHYLENE GLYCOL BY CLOSTRIDIUM GLYCOLICUM, SP. N1

PubMed Central

Gaston, Lamont W.; Stadtman, E. R.

1963-01-01

Gaston, Lamont W. (National Heart Institute, National Institutes of Health, Bethesda, Md.) and E. R. Stadtman. Fermentation of ethylene glycol by Clostridium glycolicum, sp. n. J. Bacteriol. 85:356–362. 1963.—An anaerobic organism which utilizes ethylene glycol as a source of energy and carbon has been isolated from mud. It is a long (5 μ), slender, motile, gram-positive, spore-forming rod, with peritrichous flagellae. It grows well from 22 to 37 C at pH 7.4 to 7.6, and ferments glucose, fructose, sorbitol, dulcitol, and cellulose. It does not reduce nitrates, form indole, or cause hemolysis or proteolysis except for a slight attack on coagulated egg albumin. Fifteen amino acids and the vitamins biotin and pantothenate are required for optimal growth on ethylene glycol. Analogues other than propylene glycol do not support growth. Ethylene glycol and propylene glycol are stoichiometrically converted to equal amounts of the respective acid and alcohol. PMID:13946772

Engineering redox balance through cofactor systems.

PubMed

Chen, Xiulai; Li, Shubo; Liu, Liming

2014-06-01

Redox balance plays an important role in the production of enzymes, pharmaceuticals, and chemicals. To meet the demands of industrial production, it is desirable that microbes maintain a maximal carbon flux towards target metabolites with no fluctuations in redox. This requires functional cofactor systems that support dynamic homeostasis between different redox states or functional stability in a given redox state. Redox balance can be achieved by improving the self-balance of a cofactor system, regulating the substrate balance of a cofactor system, and engineering the synthetic balance of a cofactor system. This review summarizes how cofactor systems can be manipulated to improve redox balance in microbes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mechanisms of propylene glycol and triacetin pyrolysis.

PubMed

Laino, Teodoro; Tuma, Christian; Moor, Philippe; Martin, Elyette; Stolz, Steffen; Curioni, Alessandro

2012-05-10

Propylene glycol and triacetin are chemical compounds, commonly used as food additives. Though the usage of the pure chemicals is not considered harmful when used as dietary supplements, little is known about the nature of their thermal degradation products and the impact they may have on human health. For these reasons, in this manuscript we investigate the thermal decomposition mechanisms of both neutral propylene glycol and triacetin in the gas phase by a novel simulation framework. This is based on a free energy sampling methodology followed by an accurate energy refinement. Structures, Gibbs free energy barriers, and rate constants at 800 K were computed for the different steps involved in the two pyrolytic processes. The thermal decomposition mechanisms found theoretically for propylene glycol and triacetin were validated by a qualitative experimental investigation using gas-phase chromatography-mass spectroscopy, with excellent agreement. The results provide a validation of the novel simulation framework and shed light on the potential hazard to the health that propylene glycol and triacetin may have when exposed to high temperatures.

Fasting, but Not Aging, Dramatically Alters the Redox Status of Cysteine Residues on Proteins in Drosophila melanogaster

PubMed Central

Menger, Katja E.; James, Andrew M.; Cochemé, Helena M.; Harbour, Michael E.; Chouchani, Edward T.; Ding, Shujing; Fearnley, Ian M.; Partridge, Linda; Murphy, Michael P.

2015-01-01

Summary Altering the redox state of cysteine residues on protein surfaces is an important response to environmental challenges. Although aging and fasting alter many redox processes, the role of cysteine residues is uncertain. To address this, we used a redox proteomic technique, oxidative isotope-coded affinity tags (OxICAT), to assess cysteine-residue redox changes in Drosophila melanogaster during aging and fasting. This approach enabled us to simultaneously identify and quantify the redox state of several hundred cysteine residues in vivo. Cysteine residues within young flies had a bimodal distribution with peaks at ∼10% and ∼85% reversibly oxidized. Surprisingly, these cysteine residues did not become more oxidized with age. In contrast, 24 hr of fasting dramatically oxidized cysteine residues that were reduced under fed conditions while also reducing cysteine residues that were initially oxidized. We conclude that fasting, but not aging, dramatically alters cysteine-residue redox status in D. melanogaster. PMID:26095360

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 12 2014-07-01 2014-07-01 false Glycol dehydration unit process vent... Storage Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart that must be controlled for air emissions as...

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 12 2013-07-01 2013-07-01 false Glycol dehydration unit process vent... Storage Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart that must be controlled for air emissions as...

Redox-iodometry: a new potentiometric method.

PubMed

Gottardi, Waldemar; Pfleiderer, Jörg

2005-07-01

A new iodometric method for quantifying aqueous solutions of iodide-oxidizing and iodine-reducing substances, as well as plain iodine/iodide solutions, is presented. It is based on the redox potential of said solutions after reaction with iodide (or iodine) of known initial concentration. Calibration of the system and calculations of unknown concentrations was performed on the basis of developed algorithms and simple GWBASIC-programs. The method is distinguished by a short analysis time (2-3 min) and a simple instrumentation consisting of pH/mV meter, platinum and reference electrodes. In general the feasible concentration range encompasses 0.1 to 10(-6) mol/L, although it goes down to 10(-8) mol/L (0.001 mg Cl2/L) for oxidants like active chlorine compounds. The calculated imprecision and inaccuracy of the method were found to be 0.4-0.9% and 0.3-0.8%, respectively, resulting in a total error of 0.5-1.2%. Based on the experiments, average imprecisions of 1.0-1.5% at c(Ox)>10(-5) M, 1.5-3% at 10(-5) to 10(-7) M, and 4-7% at <10(-7) M were found. Redox-iodometry is a simple, precise, and time-saving substitute for the more laborious and expensive iodometric titration method, which, like other well-established colorimetric procedures, is clearly outbalanced at low concentrations; this underlines the practical importance of redox-iodometry.

Powering Lithium-Sulfur Battery Performance by Propelling Polysulfide Redox at Sulfiphilic Hosts.

PubMed

Yuan, Zhe; Peng, Hong-Jie; Hou, Ting-Zheng; Huang, Jia-Qi; Chen, Cheng-Meng; Wang, Dai-Wei; Cheng, Xin-Bing; Wei, Fei; Zhang, Qiang

2016-01-13

Lithium-sulfur (Li-S) battery system is endowed with tremendous energy density, resulting from the complex sulfur electrochemistry involving multielectron redox reactions and phase transformations. Originated from the slow redox kinetics of polysulfide intermediates, the flood of polysulfides in the batteries during cycling induced low sulfur utilization, severe polarization, low energy efficiency, deteriorated polysulfide shuttle, and short cycling life. Herein, sulfiphilic cobalt disulfide (CoS2) was incorporated into carbon/sulfur cathodes, introducing strong interaction between lithium polysulfides and CoS2 under working conditions. The interfaces between CoS2 and electrolyte served as strong adsorption and activation sites for polar polysulfides and therefore accelerated redox reactions of polysulfides. The high polysulfide reactivity not only guaranteed effective polarization mitigation and promoted energy efficiency by 10% but also promised high discharge capacity and stable cycling performance during 2000 cycles. A slow capacity decay rate of 0.034%/cycle at 2.0 C and a high initial capacity of 1368 mAh g(-1) at 0.5 C were achieved. Since the propelling redox reaction is not limited to Li-S system, we foresee the reported strategy herein can be applied in other high-power devices through the systems with controllable redox reactions.

Dissecting Redox Biology Using Fluorescent Protein Sensors.

PubMed

Schwarzländer, Markus; Dick, Tobias P; Meyer, Andreas J; Morgan, Bruce

2016-05-01

Fluorescent protein sensors have revitalized the field of redox biology by revolutionizing the study of redox processes in living cells and organisms. Within one decade, a set of fundamental new insights has been gained, driven by the rapid technical development of in vivo redox sensing. Redox-sensitive yellow and green fluorescent protein variants (rxYFP and roGFPs) have been the central players. Although widely used as an established standard tool, important questions remain surrounding their meaningful use in vivo. We review the growing range of thiol redox sensor variants and their application in different cells, tissues, and organisms. We highlight five key findings where in vivo sensing has been instrumental in changing our understanding of redox biology, critically assess the interpretation of in vivo redox data, and discuss technical and biological limitations of current redox sensors and sensing approaches. We explore how novel sensor variants may further add to the current momentum toward a novel mechanistic and integrated understanding of redox biology in vivo. Antioxid. Redox Signal. 24, 680-712.

[Radiation therapy and redox imaging].

PubMed

Matsumoto, Ken-ichiro

2015-01-01

Radiation therapy kills cancer cells in part by flood of free radicals. Radiation ionizes and/or excites water molecules to create highly reactive species, i.e. free radicals and/or reactive oxygen species. Free radical chain reactions oxidize biologically important molecules and thereby disrupt their function. Tissue oxygen and/or redox status, which can influence the course of the free radical chain reaction, can affect the efficacy of radiation therapy. Prior observation of tissue oxygen and/or redox status is helpful for planning a safe and efficient course of radiation therapy. Magnetic resonance-based redox imaging techniques, which can estimate tissue redox status non-invasively, have been developed not only for diagnostic information but also for estimating the efficacy of treatment. Redox imaging is now spotlighted to achieve radiation theranostics.

Selenium- and tellurium-containing multifunctional redox agents as biochemical redox modulators with selective cytotoxicity.

PubMed

Jamier, Vincent; Ba, Lalla A; Jacob, Claus

2010-09-24

Various human diseases, including different types of cancer, are associated with a disturbed intracellular redox balance and oxidative stress (OS). The past decade has witnessed the emergence of redox-modulating compounds able to utilize such pre-existing disturbances in the redox state of sick cells for therapeutic advantage. Selenium- and tellurium-based agents turn the oxidizing redox environment present in certain cancer cells into a lethal cocktail of reactive species that push these cells over a critical redox threshold and ultimately kill them through apoptosis. This kind of toxicity is highly selective: normal, healthy cells remain largely unaffected, since changes to their naturally low levels of oxidizing species produce little effect. To further improve selectivity, multifunctional sensor/effector agents are now required that recognize the biochemical signature of OS in target cells. The synthesis of such compounds provides interesting challenges for chemistry in the future.

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 12 2012-07-01 2011-07-01 true Glycol dehydration unit process vent... Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Glycol dehydration unit process vent... Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 11 2013-07-01 2013-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart that must be controlled for air emissions as specified in either...

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 10 2011-07-01 2011-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 11 2014-07-01 2014-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart that must be controlled for air emissions as specified in either...

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 11 2011-07-01 2011-07-01 false Glycol dehydration unit process vent... Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 11 2012-07-01 2012-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

Stabilization of distearoylphosphatidylcholine lamellar phases in propylene glycol using cholesterol.

PubMed

Harvey, Richard D; Ara, Nargis; Heenan, Richard K; Barlow, David J; Quinn, Peter J; Lawrence, M Jayne

2013-12-02

Phospholipid vesicles (liposomes) formed in pharmaceutically acceptable nonaqueous polar solvents such as propylene glycol are of interest in drug delivery because of their ability to improve the bioavailability of drugs with poor aqueous solubility. We have demonstrated a stabilizing effect of cholesterol on lamellar phases formed by dispersion of distearoylphosphatidylcholine (DSPC) in water/propylene glycol (PG) solutions with glycol concentrations ranging from 0 to 100%. The stability of the dispersions was assessed by determining the effect of propylene glycol concentration on structural parameters of the lamellar phases using a complementary combination of X-ray and neutron scattering techniques at 25 °C and in the case of X-ray scattering at 65 °C. Significantly, although stable lamellar phases (and liposomes) were formed in all PG solutions at 25 °C, the association of the glycol with the liposomes' lamellar structures led to the formation of interdigitated phases, which were not thermostable at 65 °C. With the addition of equimolar quantities of cholesterol to the dispersions of DSPC, stable lamellar dispersions (and indeed liposomes) were formed in all propylene glycol solutions at 25 °C, with the significant lateral phase separation of the bilayer components only detectable in propylene glycol concentrations above 60% (w/w). We propose that the stability of lamellar phases of the cholesterol-containing liposomes formed in propylene glycol concentrations of up to 60% (w/w) represent potentially very valuable drug delivery vehicles for a variety of routes of administration.

Pd/NbOPO₄ multifunctional catalyst for the direct production of liquid alkanes from aldol adducts of furans.

PubMed

Xia, Qi-Neng; Cuan, Qian; Liu, Xiao-Hui; Gong, Xue-Qing; Lu, Guan-Zhong; Wang, Yan-Qin

2014-09-08

Great efforts have been made to convert renewable biomass into transportation fuels. Herein, we report the novel properties of NbO(x)-based catalysts in the hydrodeoxygenation of furan-derived adducts to liquid alkanes. Excellent activity and stability were observed with almost no decrease in octane yield (>90% throughout) in a 256 h time-on-stream test. Experimental and theoretical studies showed that NbO(x) species play the key role in C-O bond cleavage. As a multifunctional catalyst, Pd/NbOPO4 plays three roles in the conversion of aldol adducts into alkanes: 1) The noble metal (in this case Pd) is the active center for hydrogenation; 2) NbO(x) species help to cleave the C-O bond, especially of the tetrahydrofuran ring; and 3) a niobium-based solid acid catalyzes the dehydration, thus enabling the quantitative conversion of furan-derived adducts into alkanes under mild conditions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

NASA Redox system development project status

NASA Technical Reports Server (NTRS)

Nice, A. W.

1981-01-01

NASA-Redox energy storage systems developed for solar power applications and utility load leveling applications are discussed. The major objective of the project is to establish the technology readiness of Redox energy storage for transfer to industry for product development and commercialization by industry. The approach is to competitively contract to design, build, and test Redox systems progressively from preprototype to prototype multi-kW and megawatt systems and conduct supporting technology advancement tasks. The Redox electrode and membrane are fully adequate for multi-kW solar related applications and the viability of the Redox system technology as demonstrated for multi-kW solar related applications. The status of the NASA Redox Storage System Project is described along with the goals and objectives of the project elements.

Glass transition behavior of ternary disaccharide-ethylene glycol-water solutions

NASA Astrophysics Data System (ADS)

Yu, Tongxu; Zhao, Lishan; Wang, Qiang; Cao, Zexian

2017-06-01

Glass transition behavior of ternary disaccharide-ethylene glycol-water solutions, in reference to that of the binary combinations, has been investigated towards a better understanding of their cryoprotective ability. In water-deficient solutions, the disaccharides, including trehalose, sucrose and maltose, can associate with more than 100 ethylene glycol molecules to form amorphous complex, one order of magnitude larger than the corresponding hydration numbers. In water-rich solutions, a second glass transition emerges with increasing molar fraction of ethylene glycol, indicating the possible synergy of disaccharides and ethylene glycol in vitrification of the ternary aqueous solution.

Redox Flow Batteries, a Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knoxville, U. Tennessee; U. Texas Austin; U, McGill

2011-07-15

Redox flow batteries are enjoying a renaissance due to their ability to store large amounts of electrical energy relatively cheaply and efficiently. In this review, we examine the components of redox flow batteries with a focus on understanding the underlying physical processes. The various transport and kinetic phenomena are discussed along with the most common redox couples.

Redox Indicator Mice Stably Expressing Genetically Encoded Neuronal roGFP: Versatile Tools to Decipher Subcellular Redox Dynamics in Neuropathophysiology.

PubMed

Wagener, Kerstin C; Kolbrink, Benedikt; Dietrich, Katharina; Kizina, Kathrin M; Terwitte, Lukas S; Kempkes, Belinda; Bao, Guobin; Müller, Michael

2016-07-01

Reactive oxygen species (ROS) and downstream redox alterations not only mediate physiological signaling but also neuropathology. For long, ROS/redox imaging was hampered by a lack of reliable probes. Genetically encoded redox sensors overcame this gap and revolutionized (sub)cellular redox imaging. Yet, the successful delivery of sensor-coding DNA, which demands transfection/transduction of cultured preparations or stereotaxic microinjections of each subject, remains challenging. By generating transgenic mice, we aimed to overcome limiting cultured preparations, circumvent surgical interventions, and to extend effectively redox imaging to complex and adult preparations. Our redox indicator mice widely express Thy1-driven roGFP1 (reduction-oxidation-sensitive green fluorescent protein 1) in neuronal cytosol or mitochondria. Negative phenotypic effects of roGFP1 were excluded and its proper targeting and functionality confirmed. Redox mapping by ratiometric wide-field imaging reveals most oxidizing conditions in CA3 neurons. Furthermore, mitochondria are more oxidized than cytosol. Cytosolic and mitochondrial roGFP1s reliably report cell endogenous redox dynamics upon metabolic challenge or stimulation. Fluorescence lifetime imaging yields stable, but marginal, response ranges. We therefore developed automated excitation ratiometric 2-photon imaging. It offers superior sensitivity, spatial resolution, and response dynamics. Redox indicator mice enable quantitative analyses of subcellular redox dynamics in a multitude of preparations and at all postnatal stages. This will uncover cell- and compartment-specific cerebral redox signals and their defined alterations during development, maturation, and aging. Cross-breeding with other disease models will reveal molecular details on compartmental redox homeostasis in neuropathology. Combined with ratiometric 2-photon imaging, this will foster our mechanistic understanding of cellular redox signals in their full complexity

The aqueous photolysis of ethylene glycol adsorbed on geothite

USGS Publications Warehouse

Cunningham, Kirkwood M.; Goldberg, Marvin C.; Weiner, E.R.

1985-01-01

Suspensions of goethite (α-FeOOH) were photolyzed in aerated ethylene glycol-water solutions at pH 6.5, with ultraviolet light in the wavelength range300–400 nm. Under these conditions, formaldehyde and glycolaldehyde were detected as photoproducts. Quantum yields of formaldehyde production ranged from 1.9 7times; 10-5 to 2.9 × 10-4 over the ethylene glycol concentration range of 0.002-2.0 mol/ℓ, and gave evidence that the reaction occurred at the goethite surface. Quantum yields of glycolaldehyde were 20% less than those of formaldehyde, and displayed a concentration-dependent relationship with ethylene glycol similar to that of formaldehyde. Immediately after photolysis, Fe2+ was measured to be 4.6 × 10-7 mol/ℓ in an aerated suspension containing 1.3 mol/ℓ ethylene glycol, and 8.5 × 10-6 mol/ℓ in the corresponding deoxygenated suspension. Glycolaldehyde was not generated in the deoxygenated suspensions. These results are consistent with a mechanism involving the transfer of an electron from an adsorbed ethylene glycol molecule to an excited state of Fe3+ (Iron[III]) in the goethite lattice, to produce Fe2+ and an organic cation. In a series of reactions involving O2, FeOOH, and Fe2+, the organic cation decomposes to form formaldehyde and the intermediate radicals “OH and” CH2OH. OH reacts further with ethylene glycol in the presence of O2to yield glycolaldehyde. Aqueous photolysis of ethylene glycol sorbed onto goethite is typical of reactions that can occur in the aquatic environment.

Influence of propylene glycol on aqueous silica dispersions and particle-stabilized emulsions.

PubMed

Binks, Bernard P; Fletcher, Paul D I; Thompson, Michael A; Elliott, Russell P

2013-05-14

We have studied the influence of adding propylene glycol to both aqueous dispersions of fumed silica nanoparticles and emulsions of paraffin liquid and water stabilized by the same particles. In the absence of oil, aerating mixtures of aqueous propylene glycol and particles yields either stable dispersions, aqueous foams, climbing particle films, or liquid marbles depending on the glycol content and particle hydrophobicity. The presence of glycol in water promotes particles to behave as if they are more hydrophilic. Calculations of their contact angle at the air-aqueous propylene glycol surface are in agreement with these findings. In the presence of oil, particle-stabilized emulsions invert from water-in-oil to oil-in-water upon increasing either the inherent hydrophilicity of the particles or the glycol content in the aqueous phase. Stable multiple emulsions occur around phase inversion in systems of low glycol content, and completely stable, waterless oil-in-propylene glycol emulsions can also be prepared. Accounting for the surface energies at the respective interfaces allows estimation of the contact angle at the oil-polar phase interface; reasonable agreement between measured and calculated phase inversion conditions is found assuming no glycol adsorption on particle surfaces.

Processes and systems for the production of propylene glycol from glycerol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frye, John G; Oberg, Aaron A; Zacher, Alan H

2015-01-20

Processes and systems for converting glycerol to propylene glycol are disclosed. The glycerol feed is diluted with propylene glycol as the primary solvent, rather than water which is typically used. The diluted glycerol feed is sent to a reactor where the glycerol is converted to propylene glycol (as well as other byproducts) in the presence of a catalyst. The propylene glycol-containing product from the reactor is recycled as a solvent for the glycerol feed.

Redox Indicator Mice Stably Expressing Genetically Encoded Neuronal roGFP: Versatile Tools to Decipher Subcellular Redox Dynamics in Neuropathophysiology

PubMed Central

Wagener, Kerstin C.; Kolbrink, Benedikt; Dietrich, Katharina; Kizina, Kathrin M.; Terwitte, Lukas S.; Kempkes, Belinda; Bao, Guobin

2016-01-01

Abstract Aims: Reactive oxygen species (ROS) and downstream redox alterations not only mediate physiological signaling but also neuropathology. For long, ROS/redox imaging was hampered by a lack of reliable probes. Genetically encoded redox sensors overcame this gap and revolutionized (sub)cellular redox imaging. Yet, the successful delivery of sensor-coding DNA, which demands transfection/transduction of cultured preparations or stereotaxic microinjections of each subject, remains challenging. By generating transgenic mice, we aimed to overcome limiting cultured preparations, circumvent surgical interventions, and to extend effectively redox imaging to complex and adult preparations. Results: Our redox indicator mice widely express Thy1-driven roGFP1 (reduction–oxidation-sensitive green fluorescent protein 1) in neuronal cytosol or mitochondria. Negative phenotypic effects of roGFP1 were excluded and its proper targeting and functionality confirmed. Redox mapping by ratiometric wide-field imaging reveals most oxidizing conditions in CA3 neurons. Furthermore, mitochondria are more oxidized than cytosol. Cytosolic and mitochondrial roGFP1s reliably report cell endogenous redox dynamics upon metabolic challenge or stimulation. Fluorescence lifetime imaging yields stable, but marginal, response ranges. We therefore developed automated excitation ratiometric 2-photon imaging. It offers superior sensitivity, spatial resolution, and response dynamics. Innovation and Conclusion: Redox indicator mice enable quantitative analyses of subcellular redox dynamics in a multitude of preparations and at all postnatal stages. This will uncover cell- and compartment-specific cerebral redox signals and their defined alterations during development, maturation, and aging. Cross-breeding with other disease models will reveal molecular details on compartmental redox homeostasis in neuropathology. Combined with ratiometric 2-photon imaging, this will foster our mechanistic understanding

Clinically Evaluated Cancer Drugs Inhibiting Redox Signaling.

PubMed

Kirkpatrick, D Lynn; Powis, Garth

2017-02-20

There are a number of redox-active anticancer agents currently in development based on the premise that altered redox homeostasis is necessary for cancer cell's survival. Recent Advances: This review focuses on the relatively few agents that target cellular redox homeostasis to have entered clinical trial as anticancer drugs. The success rate of redox anticancer drugs has been disappointing compared to other classes of anticancer agents. This is due, in part, to our incomplete understanding of the functions of the redox targets in normal and cancer tissues, leading to off-target toxicities and low therapeutic indexes of the drugs. The field also lags behind in the use biomarkers and other means to select patients who are most likely to respond to redox-targeted therapy. If we wish to derive clinical benefit from agents that attack redox targets, then the future will require a more sophisticated understanding of the role of redox targets in cancer and the increased application of personalized medicine principles for their use. Antioxid. Redox Signal. 26, 262-273.

Regulatory mechanisms of thiol-based redox sensors: lessons learned from structural studies on prokaryotic redox sensors.

PubMed

Lee, Sang Jae; Kim, Dong-Gyun; Lee, Kyu-Yeon; Koo, Ji Sung; Lee, Bong-Jin

2018-05-17

Oxidative stresses, such as reactive oxygen species, reactive electrophilic species, reactive nitrogen species, and reactive chlorine species, can damage cellular components, leading to cellular malfunction and death. In response to oxidative stress, bacteria have evolved redox-responsive sensors that enable them to simultaneously monitor and eradicate potential oxidative stress. Specifically, redox-sensing transcription regulators react to oxidative stress by means of modifying the thiol groups of cysteine residues, functioning as part of an efficient survival mechanism for many bacteria. In general, oxidative molecules can induce changes in the three-dimensional structures of redox sensors, which, in turn, affects the transcription of specific genes in detoxification pathways and defense mechanisms. Moreover, pathogenic bacteria utilize these redox sensors for adaptation and to evade subsequent oxidative attacks from host immune defense. For this reason, the redox sensors of pathogenic bacteria are potential antibiotic targets. Understanding the regulatory mechanisms of thiol-based redox sensors in bacteria will provide insight and knowledge into the discovery of new antibiotics.

Redox-regulated chaperones.

PubMed

Kumsta, Caroline; Jakob, Ursula

2009-06-09

Redox regulation of stress proteins, such as molecular chaperones, guarantees an immediate response to oxidative stress conditions. This review focuses on the two major classes of redox-regulated chaperones, Hsp33 in bacteria and typical 2-Cys peroxiredoxins in eukaryotes. Both proteins employ redox-sensitive cysteines, whose oxidation status directly controls their affinity for unfolding proteins and therefore their chaperone function. We will first discuss Hsp33, whose oxidative stress-induced disulfide bond formation triggers the partial unfolding of the chaperone, which, in turn, leads to the exposure of a high-affinity binding site for unfolded proteins. This rapid mode of activation makes Hsp33 essential for protecting bacteria against severe oxidative stress conditions, such as hypochlorite (i.e., bleach) treatment, which leads to widespread protein unfolding and aggregation. We will compare Hsp33 to the highly abundant eukaryotic typical 2-Cys peroxiredoxin, whose oxidative stress-induced sulfinic acid formation turns the peroxidase into a molecular chaperone in vitro and presumably in vivo. These examples illustrate how proteins use reversible cysteine modifications to rapidly adjust to oxidative stress conditions and demonstrate that redox regulation plays a vital role in protecting organisms against reactive oxygen species-mediated cell death.

Nitric oxide-releasing prodrug triggers cancer cell death through deregulation of cellular redox balance☆

PubMed Central

Maciag, Anna E.; Holland, Ryan J.; Robert Cheng, Y.-S.; Rodriguez, Luis G.; Saavedra, Joseph E.; Anderson, Lucy M.; Keefer, Larry K.

2013-01-01

JS-K is a nitric oxide (NO)-releasing prodrug of the O2-arylated diazeniumdiolate family that has demonstrated pronounced cytotoxicity and antitumor properties in a variety of cancer models both in vitro and in vivo. The current study of the metabolic actions of JS-K was undertaken to investigate mechanisms of its cytotoxicity. Consistent with model chemical reactions, the activating step in the metabolism of JS-K in the cell is the dearylation of the diazeniumdiolate by glutathione (GSH) via a nucleophilic aromatic substitution reaction. The resulting product (CEP/NO anion) spontaneously hydrolyzes, releasing two equivalents of NO. The GSH/GSSG redox couple is considered to be the major redox buffer of the cell, helping maintain a reducing environment under basal conditions. We have quantified the effects of JS-K on cellular GSH content, and show that JS-K markedly depletes GSH, due to JS-K's rapid uptake and cascading release of NO and reactive nitrogen species. The depletion of GSH results in alterations in the redox potential of the cellular environment, initiating MAPK stress signaling pathways, and inducing apoptosis. Microarray analysis confirmed signaling gene changes at the transcriptional level and revealed alteration in the expression of several genes crucial for maintenance of cellular redox homeostasis, as well as cell proliferation and survival, including MYC. Pre-treating cells with the known GSH precursor and nucleophilic reducing agent N-acetylcysteine prevented the signaling events that lead to apoptosis. These data indicate that multiplicative depletion of the reduced glutathione pool and deregulation of intracellular redox balance are important initial steps in the mechanism of JS-K's cytotoxic action. PMID:24024144

Electrolytes Based on TEMPO–Co Tandem Redox Systems Outperform Single Redox Systems in Dye‐sensitized Solar Cells

PubMed Central

Cong, Jiayan; Hao, Yan; Boschloo, Gerrit

2014-01-01

Abstract A new TEMPO–Co tandem redox system with TEMPO and Co(bpy)3 2+/3+ has been investigated for the use in dye‐sensitized solar cells (DSSCs). A large open‐circuit voltage (V OC) increase, from 862 mV to 965 mV, was observed in the tandem redox system, while the short‐circuit current density (J SC) was maintained. The conversion efficiency was observed to increase from 7.1 % for cells containing the single Co(bpy)3 2+/3+ redox couple, to 8.4 % for cells containing the TEMPO–Co tandem redox system. The reason for the increase in V OC and overall efficiency is ascribed to the involvement of partial regeneration of the sensitizing dye molecules by TEMPO. This assumption can be verified through the observed much faster regeneration dynamics exhibited in the presence of the tandem system. Using the tandem redox system, the faster recombination problem of the single TEMPO redox couple is resolved and the mass‐transport of the metal‐complex‐based electrolyte is also improved. This TEMPO–Co tandem system is so far the most effienct tandem redox electrolyte reported not involving iodine. The current results show a promising future for tandem system as replacements for single redox systems in electrolytes for DSSCs. PMID:25504818

Analysis of glycols, glycol ethers, and other volatile organic compounds present in household water-based hand pump sprays.

PubMed

Kawakami, Tsuyoshi; Isama, Kazuo; Tanaka-Kagawa, Toshiko; Jinnno, Hideto

2017-11-10

The aim of this investigation is to clarify the types and concentrations of VOCs present in various commercial household water-based hand pump spray products used in Japan, and to estimate their average concentrations in indoor air when the spray product is used. We selected glycol and glycol ethers as the main target compounds, as these chemicals were detected at high frequencies and concentrations in a national survey of Japanese indoor air pollution. The extraction of these chemicals using graphite carbon cartridges was examined, with good recoveries and reproducibilities being obtained. Eighteen chemicals were analyzed in 54 commercial products and 8 chemicals were detected. More specifically, dipropylene glycol (DPG) was present in 44 samples (1.1 × 10 1 -1.8 × 10 4 μg/mL); propylene glycol (PG) was present in 22 samples (1.5 × 10 1 -2.9 × 10 4 μg/mL); diethylene glycol monoethyl ether (DGMEE) was found in 15 samples (trace amount-1.9 × 10 3 μg/mL); diethylene glycol (DEG) was present in 9 samples (1.0 × 10 1 -2.4 × 10 3 μg/mL); 1,3-butandiol (13BG) was found in 5 samples (trace amount-7.4 × 10 3 μg/mL); 2-ethyl-1-hexanol (2E1H) was detected in 5 samples (3.2 × 10 -1 -4.4 × 10 1 μg/mL); diethylene glycol monobutyl ether (DGMBE) was present in 4 samples (2.1 × 10 1 -7.1 × 10 1 μg/mL); and 3-methoxy-3-methylbutanol (MMB) was found in 2 samples (2.4 × 10 1 -4.7 × 10 2 μg/mL). In addition, the average concentrations of these chemicals in indoor air were estimated using their maximum concentrations observed in the spray product. The estimated average concentrations of the chemicals in indoor air were determined to range between 1.0 × 10 -2 and 1.0 mg/m 3 , with the exception of 2E1H and DGMBE. Furthermore, the estimated average concentrations of PG, 13BG, and DGMEE in indoor air were comparable to or higher than those reported in a national survey of Japanese indoor air pollution. It therefore appeared that household water-based hand pump

Experimental Evidence for a Hydride Transfer Mechanism in Plant Glycolate Oxidase Catalysis*

PubMed Central

Dellero, Younès; Mauve, Caroline; Boex-Fontvieille, Edouard; Flesch, Valérie; Jossier, Mathieu; Tcherkez, Guillaume; Hodges, Michael

2015-01-01

In plants, glycolate oxidase is involved in the photorespiratory cycle, one of the major fluxes at the global scale. To clarify both the nature of the mechanism and possible differences in glycolate oxidase enzyme chemistry from C3 and C4 plant species, we analyzed kinetic parameters of purified recombinant C3 (Arabidopsis thaliana) and C4 (Zea mays) plant enzymes and compared isotope effects using natural and deuterated glycolate in either natural or deuterated solvent. The 12C/13C isotope effect was also investigated for each plant glycolate oxidase protein by measuring the 13C natural abundance in glycolate using natural or deuterated glycolate as a substrate. Our results suggest that several elemental steps were associated with an hydrogen/deuterium isotope effect and that glycolate α-deprotonation itself was only partially rate-limiting. Calculations of commitment factors from observed kinetic isotope effect values support a hydride transfer mechanism. No significant differences were seen between C3 and C4 enzymes. PMID:25416784

Redox-Directed Cancer Therapeutics: Molecular Mechanisms and Opportunities

PubMed Central

2009-01-01

Abstract Redox dysregulation originating from metabolic alterations and dependence on mitogenic and survival signaling through reactive oxygen species represents a specific vulnerability of malignant cells that can be selectively targeted by redox chemotherapeutics. This review will present an update on drug discovery, target identification, and mechanisms of action of experimental redox chemotherapeutics with a focus on pro- and antioxidant redox modulators now in advanced phases of preclinal and clinical development. Recent research indicates that numerous oncogenes and tumor suppressor genes exert their functions in part through redox mechanisms amenable to pharmacological intervention by redox chemotherapeutics. The pleiotropic action of many redox chemotherapeutics that involves simultaneous modulation of multiple redox sensitive targets can overcome cancer cell drug resistance originating from redundancy of oncogenic signaling and rapid mutation. Moreover, some redox chemotherapeutics may function according to the concept of synthetic lethality (i.e., drug cytotoxicity is confined to cancer cells that display loss of function mutations in tumor suppressor genes or upregulation of oncogene expression). The impressive number of ongoing clinical trials that examine therapeutic performance of novel redox drugs in cancer patients demonstrates that redox chemotherapy has made the crucial transition from bench to bedside. Antioxid. Redox Signal. 11, 3013–3069. PMID:19496700

21 CFR 172.712 - 1,3-Butylene glycol.

Code of Federal Regulations, 2014 CFR

2014-04-01

... ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Other Specific Usage Additives § 172.712 1,3-Butylene glycol. The food additive 1,3-butylene glycol (CAS Reg. No. 107-88-0) may be safely... condensation of acetaldehyde followed by catalytic hydrogenation. (b) The food additive shall conform to the...

Concentration of Nicotine and Glycols in 27 Electronic Cigarette Formulations

PubMed Central

Peace, Michelle R.; Baird, Tyson R.; Smith, Nathaniel; Wolf, Carl E.; Poklis, Justin L.; Poklis, Alphonse

2016-01-01

Personal battery-powered vaporizers or electronic cigarettes were developed to deliver a nicotine vapor such that smokers could simulate smoking tobacco without the inherent pathology of inhaled tobacco smoke. Electronic cigarettes and their e-cigarette liquid formulations are virtually unregulated. These formulations are typically composed of propylene glycol and/or glycerin, flavoring components and an active drug, such as nicotine. Twenty-seven e-cigarette liquid formulations that contain nicotine between 6 and 22 mg/L were acquired within the USA and analyzed by various methods to determine their contents. They were screened by Direct Analysis in Real Time™ Mass Spectrometry (DART-MS). Nicotine was confirmed and quantitated by high-performance liquid chromatography–tandem mass spectrometry, and the glycol composition was confirmed and quantitated by gas chromatography–mass spectrometry. The DART-MS screening method was able to consistently identify the exact mass peaks resulting from the protonated molecular ion of nicotine, glycol and a number of flavor additives within 5 mmu. Nicotine concentrations were determined to range from 45 to 131% of the stated label concentration, with 18 of the 27 have >10% variance. Glycol composition was generally accurate to the product description, with only one exception where the propylene glycol to glycerin percentage ratio was stated as 50:50 and the determined concentration of propylene glycol to glycerin was 81:19 (% v/v). No unlabeled glycols were detected in these formulations. PMID:27165804

Solubility of pioglitazone hydrochloride in binary mixtures of polyethylene glycol 400 with ethanol, propylene glycol, N-methyl-2-pyrrolidone, and water at 25 degrees C.

PubMed

Jouyban, Abolghasem; Soltanpour, Shahla

2010-09-01

The solubility of pioglitazone hydrochloride in binary mixtures of polyethylene glycol 400 with ethanol, N-methyl-2-pyrrolidone, propylene glycol, and water at 25 degrees C are reported. The generated data are fitted to the Jouyban-Acree model and the mean relative deviations are 2.6%, 1.5%, 5.8%, and 7.4%, respectively for ethanol, N-methyl-2-pyrrolidone, propylene glycol, and water.

Imaging dynamic redox processes with genetically encoded probes.

PubMed

Ezeriņa, Daria; Morgan, Bruce; Dick, Tobias P

2014-08-01

Redox signalling plays an important role in many aspects of physiology, including that of the cardiovascular system. Perturbed redox regulation has been associated with numerous pathological conditions; nevertheless, the causal relationships between redox changes and pathology often remain unclear. Redox signalling involves the production of specific redox species at specific times in specific locations. However, until recently, the study of these processes has been impeded by a lack of appropriate tools and methodologies that afford the necessary redox species specificity and spatiotemporal resolution. Recently developed genetically encoded fluorescent redox probes now allow dynamic real-time measurements, of defined redox species, with subcellular compartment resolution, in intact living cells. Here we discuss the available genetically encoded redox probes in terms of their sensitivity and specificity and highlight where uncertainties or controversies currently exist. Furthermore, we outline major goals for future probe development and describe how progress in imaging methodologies will improve our ability to employ genetically encoded redox probes in a wide range of situations. This article is part of a special issue entitled "Redox Signalling in the Cardiovascular System." Copyright © 2014 Elsevier Ltd. All rights reserved.

ProPhenol-Catalyzed Asymmetric Additions by Spontaneously Assembled Dinuclear Main Group Metal Complexes

PubMed Central

2016-01-01

Conspectus The development of catalytic enantioselective transformations has been the focus of many research groups over the past half century and is of paramount importance to the pharmaceutical and agrochemical industries. Since the award of the Nobel Prize in 2001, the field of enantioselective transition metal catalysis has soared to new heights, with the development of more efficient catalysts and new catalytic transformations at increasing frequency. Furthermore, catalytic reactions that allow higher levels of redox- and step-economy are being developed. Thus, alternatives to asymmetric alkene dihydroxylation and the enantioselective reduction of α,β-unsaturated ketones can invoke more strategic C–C bond forming reactions, such as asymmetric aldol reactions of an aldehyde with α-hydroxyketone donors or enantioselective alkynylation of an aldehyde, respectively. To facilitate catalytic enantioselective addition reactions, including the aforementioned aldol and alkynylation reactions, our lab has developed the ProPhenol ligand. In this Account, we describe the development and application of the ProPhenol ligand for asymmetric additions of both carbon- and heteroatom-based nucleophiles to various electrophiles. The ProPhenol ligand spontaneously forms chiral dinuclear metal complexes when treated with an alkyl metal reagent, such as Et2Zn or Bu2Mg. The resulting complex contains both a Lewis acidic site to activate an electrophile and a Brønsted basic site to deprotonate a pronucleophile. Initially, our research focused on the use of Zn-ProPhenol complexes to facilitate the direct aldol reaction. Fine tuning of the reaction through ligand modification and the use of additives enabled the direct aldol reaction to proceed in high yields and stereoselectivities with a broad range of donor substrates, including acetophenones, methyl ynones, methyl vinyl ketone, acetone, α-hydroxy carbonyl compounds, and glycine Schiff bases. Additionally, an analogous

Subcellular Redox Signaling.

PubMed

Zhu, Liping; Lu, Yankai; Zhang, Jiwei; Hu, Qinghua

2017-01-01

Oxidative and antioxidative system of cells and tissues maintains a balanced state under physiological conditions. A disruption in this balance of redox status has been associated with numerous pathological processes. Reactive oxygen species (ROS) as a major redox signaling generates in a spatiotemporally dependent manner. Subcellular organelles such as mitochondria, endoplasmic reticulum, plasma membrane and nuclei contribute to the production of ROS. In addition to downstream effects of ROS signaling regulated by average ROS changes in cytoplasm, whether subcelluar ROS mediate biological effect(s) has drawn greater attentions. With the advance in redox-sensitive probes targeted to different subcellular compartments, the investigation of subcellular ROS signaling and its associated cellular function has become feasible. In this review, we discuss the subcellular ROS signaling, with particular focus on mechanisms of subcellular ROS production and its downstream effects.

Thioredoxin links redox to the regulation of fundamental processes of plant mitochondria

PubMed Central

Balmer, Yves; Vensel, William H.; Tanaka, Charlene K.; Hurkman, William J.; Gelhaye, Eric; Rouhier, Nicolas; Jacquot, Jean-Pierre; Manieri, Wanda; Schürmann, Peter; Droux, Michel; Buchanan, Bob B.

2004-01-01

Mitochondria contain thioredoxin (Trx), a regulatory disulfide protein, and an associated flavoenzyme, NADP/Trx reductase, which provide a link to NADPH in the organelle. Unlike animal and yeast counterparts, the function of Trx in plant mitochondria is largely unknown. Accordingly, we have applied recently devised proteomic approaches to identify soluble Trx-linked proteins in mitochondria isolated from photosynthetic (pea and spinach leaves) and heterotrophic (potato tubers) sources. Application of the mitochondrial extracts to mutant Trx affinity columns in conjunction with proteomics led to the identification of 50 potential Trx-linked proteins functional in 12 processes: photorespiration, citric acid cycle and associated reactions, lipid metabolism, electron transport, ATP synthesis/transformation, membrane transport, translation, protein assembly/folding, nitrogen metabolism, sulfur metabolism, hormone synthesis, and stress-related reactions. Almost all of these targets were also identified by a fluorescent gel electrophoresis procedure in which reduction by Trx can be observed directly. In some cases, the processes targeted by Trx depended on the source of the mitochondria. The results support the view that Trx acts as a sensor and enables mitochondria to adjust key reactions in accord with prevailing redox state. These and earlier findings further suggest that, by sensing redox in chloroplasts and mitochondria, Trx enables the two organelles of photosynthetic tissues to communicate by means of a network of transportable metabolites such as dihydroxyacetone phosphate, malate, and glycolate. In this way, light absorbed and processed by means of chlorophyll can be perceived and function in regulating fundamental mitochondrial processes akin to its mode of action in chloroplasts. PMID:14983062

Thioredoxin links redox to the regulation of fundamental processes of plant mitochondria.

PubMed

Balmer, Yves; Vensel, William H; Tanaka, Charlene K; Hurkman, William J; Gelhaye, Eric; Rouhier, Nicolas; Jacquot, Jean-Pierre; Manieri, Wanda; Schürmann, Peter; Droux, Michel; Buchanan, Bob B

2004-02-24

Mitochondria contain thioredoxin (Trx), a regulatory disulfide protein, and an associated flavoenzyme, NADP/Trx reductase, which provide a link to NADPH in the organelle. Unlike animal and yeast counterparts, the function of Trx in plant mitochondria is largely unknown. Accordingly, we have applied recently devised proteomic approaches to identify soluble Trx-linked proteins in mitochondria isolated from photosynthetic (pea and spinach leaves) and heterotrophic (potato tubers) sources. Application of the mitochondrial extracts to mutant Trx affinity columns in conjunction with proteomics led to the identification of 50 potential Trx-linked proteins functional in 12 processes: photorespiration, citric acid cycle and associated reactions, lipid metabolism, electron transport, ATP synthesis/transformation, membrane transport, translation, protein assembly/folding, nitrogen metabolism, sulfur metabolism, hormone synthesis, and stress-related reactions. Almost all of these targets were also identified by a fluorescent gel electrophoresis procedure in which reduction by Trx can be observed directly. In some cases, the processes targeted by Trx depended on the source of the mitochondria. The results support the view that Trx acts as a sensor and enables mitochondria to adjust key reactions in accord with prevailing redox state. These and earlier findings further suggest that, by sensing redox in chloroplasts and mitochondria, Trx enables the two organelles of photosynthetic tissues to communicate by means of a network of transportable metabolites such as dihydroxyacetone phosphate, malate, and glycolate. In this way, light absorbed and processed by means of chlorophyll can be perceived and function in regulating fundamental mitochondrial processes akin to its mode of action in chloroplasts.

The effect of the distance between acidic site and basic site immobilized on mesoporous solid on the activity in catalyzing aldol condensation

NASA Astrophysics Data System (ADS)

Yu, Xiaofang; Yu, Xiaobo; Wu, Shujie; Liu, Bo; Liu, Heng; Guan, Jingqi; Kan, Qiubin

2011-02-01

Acid-base bifunctional heterogeneous catalysts containing carboxylic and amine groups, which were immobilized at defined distance from one another on the mesoporous solid were synthesized by immobilizing lysine onto carboxyl-SBA-15. The obtained materials were characterized by X-ray diffraction (XRD), N 2 adsorption, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron micrographs (SEM), transmission electron micrographs (TEM), elemental analysis, and back titration. Proximal-C-A-SBA-15 with a proximal acid-base distance was more active than maximum-C-A-SBA-15 with a maximum acid-base distance in aldol condensation reaction between acetone and various aldehydes. It appears that the distance between acidic site and basic site immobilized on mesoporous solid should be an essential factor for catalysis optimization.

Diethylene glycol dinitrate (DEGDN)

Integrated Risk Information System (IRIS)

Diethylene glycol dinitrate ( DEGDN ) ; CASRN 693 - 21 - 0 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

Comparison of Polyethylene Glycol-Electrolyte Solution vs Polyethylene Glycol-3350 for the Treatment of Fecal Impaction in Pediatric Patients.

PubMed

Boles, Erin E; Gaines, Cameryn L; Tillman, Emma M

2015-01-01

The objective of this study was to evaluate the safety and efficacy of polyethylene glycol-electrolyte solution vs polyethylene glycol-3350 for the treatment of fecal impaction in pediatric patients. A retrospective, observational, institutional review board-approved study was conducted over a 1-year time period. Patients were included in the study if they were admitted to the hospital with a diagnosis of fecal impaction or constipation and were treated with either polyethylene glycol-electrolyte solution (PEG-ES) or polyethylene glycol-3350 (PEG-3350). Patients were excluded if they were discharged prior to resolution of treatment and/or did not receive PEG-ES or PEG-3350. Fifty-one patients (ranging in age from 1 month to 15 years) were evaluated: 23 patients received PEG-ES and 28 patients received PEG-3350. Sex, race, age, and weight were not statistically different between the 2 groups. Resolution of fecal impaction was not significantly different between PEG-ES vs PEG-3350 (87% and 86%, respectively; p = 0.87). There was only 1 reported side effect with PEG-3350, vs 11 reported side effects with PEG-ES (p < 0.01). Theses results suggest that PEG-3350 is as effective as PEG-ES for the treatment of fecal impaction in pediatric patients and is associated with fewer side effects.

Interactions between magnetite and humic substances: redox reactions and dissolution processes.

PubMed

Sundman, Anneli; Byrne, James M; Bauer, Iris; Menguy, Nicolas; Kappler, Andreas

2017-10-19

Humic substances (HS) are redox-active compounds that are ubiquitous in the environment and can serve as electron shuttles during microbial Fe(III) reduction thus reducing a variety of Fe(III) minerals. However, not much is known about redox reactions between HS and the mixed-valent mineral magnetite (Fe 3 O 4 ) that can potentially lead to changes in Fe(II)/Fe(III) stoichiometry and even dissolve the magnetite. To address this knowledge gap, we incubated non-reduced (native) and reduced HS with four types of magnetite that varied in particle size and solid-phase Fe(II)/Fe(III) stoichiometry. We followed dissolved and solid-phase Fe(II) and Fe(III) concentrations over time to quantify redox reactions between HS and magnetite. Magnetite redox reactions and dissolution processes with HS varied depending on the initial magnetite and HS properties. The interaction between biogenic magnetite and reduced HS resulted in dissolution of the solid magnetite mineral, as well as an overall reduction of the magnetite. In contrast, a slight oxidation and no dissolution was observed when native and reduced HS interacted with 500 nm magnetite. This variability in the solubility and electron accepting and donating capacity of the different types of magnetite is likely an effect of differences in their reduction potential that is correlated to the magnetite Fe(II)/Fe(III) stoichiometry, particle size, and crystallinity. Our study suggests that redox-active HS play an important role for Fe redox speciation within minerals such as magnetite and thereby influence the reactivity of these Fe minerals and their role in biogeochemical Fe cycling. Furthermore, such processes are also likely to have an effect on the fate of other elements bound to the surface of Fe minerals.

Minimizing analyte electrolysis in electrospray ionization mass spectrometry using a redox buffer coated emitter electrode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peintler-Krivan, Emese; Van Berkel, Gary J; Kertesz, Vilmos

2010-01-01

An emitter electrode with an electroactive poly(pyrrole) (PPy) polymer film coating was constructed for use in electrospray ionization mass spectrometry (ESI-MS). The PPy film acted as a surface-attached redox buffer limiting the interfacial potential of the emitter electrode. While extensive oxidation of selected analytes (reserpine and amodiaquine) was observed in positive ion mode ESI using a bare metal (gold) emitter electrode, the oxidation was suppressed for these same analytes when using the PPy-coated electrode. A semi-quantitative relationship between the rate of oxidation observed and the interfacial potential of the emitter electrode was shown. The redox buffer capacity, and therefore themore » lifetime of the redox buffering effect, correlated with the oxidation potential of the analyte and with the magnitude of the film charge capacity. Online reduction of the PPy polymer layer using negative ion mode ESI between analyte injections was shown to successfully restore the redox buffering capacity of the polymer film to its initial state.« less

Molecular structure impacts on secondary organic aerosol formation from glycol ethers

NASA Astrophysics Data System (ADS)

Li, Lijie; Cocker, David R.

2018-05-01

Glycol ethers, a class of widely used solvents in consumer products, are often considered exempt as volatile organic compounds based on their vapor pressure or boiling points by regulatory agencies. However, recent studies found that glycol ethers volatilize at ambient conditions nearly as rapidly as the traditional high-volatility solvents indicating the potential of glycol ethers to form secondary organic aerosol (SOA). This is the first work on SOA formation from glycol ethers. The impact of molecular structure, specifically -OH, on SOA formation from glycol ethers and related ethers are investigated in the work. Ethers with and without -OH, with methyl group hindrance on -OH and with -OH at different location are studied in the presence of NOX and under "NOX free" conditions. Photooxidation experiments under different oxidation conditions confirm that the processing of ethers is a combination of carbonyl formation, cyclization and fragmentation. Bulk SOA chemical composition analysis and oxidation products identified in both gas and particle phase suggests that the presence and location of -OH in the carbon bond of ethers determine the occurrence of cyclization mechanism during ether oxidation. The cyclization is proposed as a critical SOA formation mechanism to prevent the formation of volatile compounds from fragmentation during the oxidation of ethers. Glycol ethers with -CH2-O-CH2CH2OH structure is found to readily form cyclization products, especially with the presence of NOx, which is more relevant to urban atmospheric conditions than without NOx. Glycol ethers are evaluated as dominating SOA precursors among all ethers studied. It is estimated that the contribution of glycol ethers to anthropogenic SOA is roughly 1% of the current organic aerosol from mobile sources. The contribution of glycol ethers to anthropogenic SOA is roughly 1% of the current organic aerosol from mobile sources and will play a more important role in future anthropogenic SOA

Concentration of Nicotine and Glycols in 27 Electronic Cigarette Formulations.

PubMed

Peace, Michelle R; Baird, Tyson R; Smith, Nathaniel; Wolf, Carl E; Poklis, Justin L; Poklis, Alphonse

2016-07-01

Personal battery-powered vaporizers or electronic cigarettes were developed to deliver a nicotine vapor such that smokers could simulate smoking tobacco without the inherent pathology of inhaled tobacco smoke. Electronic cigarettes and their e-cigarette liquid formulations are virtually unregulated. These formulations are typically composed of propylene glycol and/or glycerin, flavoring components and an active drug, such as nicotine. Twenty-seven e-cigarette liquid formulations that contain nicotine between 6 and 22 mg/L were acquired within the USA and analyzed by various methods to determine their contents. They were screened by Direct Analysis in Real Time™ Mass Spectrometry (DART-MS). Nicotine was confirmed and quantitated by high-performance liquid chromatography-tandem mass spectrometry, and the glycol composition was confirmed and quantitated by gas chromatography-mass spectrometry. The DART-MS screening method was able to consistently identify the exact mass peaks resulting from the protonated molecular ion of nicotine, glycol and a number of flavor additives within 5 mmu. Nicotine concentrations were determined to range from 45 to 131% of the stated label concentration, with 18 of the 27 have >10% variance. Glycol composition was generally accurate to the product description, with only one exception where the propylene glycol to glycerin percentage ratio was stated as 50:50 and the determined concentration of propylene glycol to glycerin was 81:19 (% v/v). No unlabeled glycols were detected in these formulations. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Rapid Diagnosis of Ethylene Glycol Poisoning by Urine Microscopy.

PubMed

Sheta, Hussam Mahmoud; Al-Najami, Issam; Christensen, Heidi Dahl; Madsen, Jonna Skov

2018-06-14

BACKGROUND Ethylene glycol poisoning remains an important presentation to Emergency Departments. Quick diagnosis and treatment are essential to prevent renal failure and life-threating complications. CASE REPORT In this case report, we present a patient who was admitted unconscious to the hospital. Ethylene glycol poisoning was immediately suspected, because the patient had previously been hospitalized with similar symptoms after intake of antifreeze coolant. A urine sample was sent for microscopy and showed multiple calcium oxalate monohydrate (COM) crystals, which supported the clinical suspicion of ethylene glycol poisoning. The patient was treated with continuous intravenous ethyl alcohol infusion and hemodialysis. Two days after admission, the patient was awake and in clinical recovery. CONCLUSIONS Demonstration of COM crystals using microscopy of a urine sample adds valuable information supporting the clinical suspicion of ethylene glycol poisoning, and may serve as an easy, quick, and cheap method that can be performed in any emergency setting.

Early, patient-initiated treatment of herpes labialis with topical 10% acyclovir.

PubMed Central

Spruance, S L; Crumpacker, C S; Schnipper, L E; Kern, E R; Marlowe, S; Arndt, K A; Overall, J C

1984-01-01

To determine whether topical acyclovir in polyethylene glycol could reduce the severity of herpes simplex labialis if applied immediately after onset of a recurrence, 10% acyclovir in polyethylene glycol ointment or polyethylene glycol alone was prospectively dispensed to 352 patients in a double-blind, randomized trial. Sixty-nine subjects initiated treatment in the prodrome (57%) or erythema (43%) stage and were followed by clinical and virological criteria. The healing time (6.0 days), maximum lesion area (42 mm2), vesicle or ulcer formation (91%), and maximum lesion virus titer (4.8 log10 PFU) in the drug recipients were not reduced in comparison with those who received the vehicle (5.2 days, 30 mm2, 75%, and 4.5 log10 PFU, respectively). Topical acyclovir in polyethylene glycol was ineffective for the treatment of herpes labialis despite an optimum therapeutic opportunity. PMID:6732224

Redox biology of tuberculosis pathogenesis.

PubMed

Trivedi, Abhishek; Singh, Nisha; Bhat, Shabir Ahmed; Gupta, Pawan; Kumar, Ashwani

2012-01-01

Mycobacterium tuberculosis (Mtb) is one of the most successful human pathogens. Mtb is persistently exposed to numerous oxidoreductive stresses during its pathogenic cycle of infection and transmission. The distinctive ability of Mtb, not only to survive the redox stress manifested by the host but also to use it for synchronizing the metabolic pathways and expression of virulence factors, is central to its success as a pathogen. This review describes the paradigmatic redox and hypoxia sensors employed by Mtb to continuously monitor variations in the intracellular redox state and the surrounding microenvironment. Two component proteins, namely, DosS and DosT, are employed by Mtb to sense changes in oxygen, nitric oxide, and carbon monoxide levels, while WhiB3 and anti-sigma factor RsrA are used to monitor changes in intracellular redox state. Using these and other unidentified redox sensors, Mtb orchestrates its metabolic pathways to survive in nutrient-deficient, acidic, oxidative, nitrosative, and hypoxic environments inside granulomas or infectious lesions. A number of these metabolic pathways are unique to mycobacteria and thus represent potential drug targets. In addition, Mtb employs versatile machinery of the mycothiol and thioredoxin systems to ensure a reductive intracellular environment for optimal functioning of its proteins even upon exposure to oxidative stress. Mtb also utilizes a battery of protective enzymes, such as superoxide dismutase (SOD), catalase (KatG), alkyl hydroperoxidase (AhpC), and peroxiredoxins, to neutralize the redox stress generated by the host immune system. This chapter reviews the current understanding of mechanisms employed by Mtb to sense and neutralize redox stress and their importance in TB pathogenesis and drug development. Copyright © 2012 Elsevier Ltd. All rights reserved.

21 CFR 589.1001 - Propylene glycol in or on cat food.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Propylene glycol in or on cat food. 589.1001... Listing of Specific Substances Prohibited From Use in Animal Food or Feed § 589.1001 Propylene glycol in or on cat food. The Food and Drug Administration has determined that propylene glycol in or on cat...

21 CFR 589.1001 - Propylene glycol in or on cat food.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Propylene glycol in or on cat food. 589.1001... Listing of Specific Substances Prohibited From Use in Animal Food or Feed § 589.1001 Propylene glycol in or on cat food. The Food and Drug Administration has determined that propylene glycol in or on cat...

21 CFR 589.1001 - Propylene glycol in or on cat food.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Propylene glycol in or on cat food. 589.1001... Listing of Specific Substances Prohibited From Use in Animal Food or Feed § 589.1001 Propylene glycol in or on cat food. The Food and Drug Administration has determined that propylene glycol in or on cat...

Triethylene glycol monobutyl ether

Integrated Risk Information System (IRIS)

Triethylene glycol monobutyl ether ; CASRN 143 - 22 - 6 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 fo

Triethylene glycol monoethyl ether

Integrated Risk Information System (IRIS)

Triethylene glycol monoethyl ether ; CASRN 112 - 50 - 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 fo

Propylene glycol monoethyl ether

Integrated Risk Information System (IRIS)

Propylene glycol monoethyl ether ; CASRN 52125 - 53 - 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 fo

Zinc and the modulation of redox homeostasis

PubMed Central

Oteiza, Patricia I.

2012-01-01

Zinc, a redox inactive metal, has been long viewed as a component of the antioxidant network, and growing evidence points to its involvement in redox-regulated signaling. These actions are exerted through several mechanisms based on the unique chemical and functional properties of zinc. Overall, zinc contributes to maintain the cell redox balance through different mechanisms including: i) the regulation of oxidant production and metal-induced oxidative damage; ii) the dynamic association of zinc with sulfur in protein cysteine clusters, from which the metal can be released by nitric oxide, peroxides, oxidized glutathione and other thiol oxidant species; iii) zinc-mediated induction of the zinc-binding protein metallothionein, which releases the metal under oxidative conditions and act per se scavenging oxidants; iv) the involvement of zinc in the regulation of glutathione metabolism and of the overall protein thiol redox status; and v) a direct or indirect regulation of redox signaling. Findings of oxidative stress, altered redox signaling, and associated cell/tissue disfunction in cell and animal models of zinc deficiency, stress the relevant role of zinc in the preservation of cell redox homeostasis. However, while the participation of zinc in antioxidant protection, redox sensing, and redox-regulated signaling is accepted, the involved molecules, targets and mechanisms are still partially known and the subject of active research. PMID:22960578

Redox Regulation of Endothelial Cell Fate

PubMed Central

Song, Ping; Zou, Ming-Hui

2014-01-01

Endothelial cells (ECs) are present throughout blood vessels and have variable roles in both physiological and pathological settings. EC fate is altered and regulated by several key factors in physiological or pathological conditions. Reactive nitrogen species and reactive oxygen species derived from NAD(P)H oxidases, mitochondria, or nitric oxide-producing enzymes are not only cytotoxic but also compose a signaling network in the redox system. The formation, actions, key molecular interactions, and physiological and pathological relevance of redox signals in ECs remain unclear. We review the identities, sources, and biological actions of oxidants and reductants produced during EC function or dysfunction. Further, we discuss how ECs shape key redox sensors and examine the biological functions, transcriptional responses, and post-translational modifications evoked by the redox system in ECs. We summarize recent findings regarding the mechanisms by which redox signals regulate the fate of ECs and address the outcome of altered EC fate in health and disease. Future studies will examine if the redox biology of ECs can be targeted in pathophysiological conditions. PMID:24633153

Redox Proteomics in Selected Neurodegenerative Disorders: From Its Infancy to Future Applications

PubMed Central

Perluigi, Marzia; Reed, Tanea; Muharib, Tasneem; Hughes, Christopher P.; Robinson, Renã A.S.; Sultana, Rukhsana

2012-01-01

Abstract Several studies demonstrated that oxidative damage is a characteristic feature of many neurodegenerative diseases. The accumulation of oxidatively modified proteins may disrupt cellular functions by affecting protein expression, protein turnover, cell signaling, and induction of apoptosis and necrosis, suggesting that protein oxidation could have both physiological and pathological significance. For nearly two decades, our laboratory focused particular attention on studying oxidative damage of proteins and how their chemical modifications induced by reactive oxygen species/reactive nitrogen species correlate with pathology, biochemical alterations, and clinical presentations of Alzheimer's disease. This comprehensive article outlines basic knowledge of oxidative modification of proteins and lipids, followed by the principles of redox proteomics analysis, which also involve recent advances of mass spectrometry technology, and its application to selected age-related neurodegenerative diseases. Redox proteomics results obtained in different diseases and animal models thereof may provide new insights into the main mechanisms involved in the pathogenesis and progression of oxidative-stress-related neurodegenerative disorders. Redox proteomics can be considered a multifaceted approach that has the potential to provide insights into the molecular mechanisms of a disease, to find disease markers, as well as to identify potential targets for drug therapy. Considering the importance of a better understanding of the cause/effect of protein dysfunction in the pathogenesis and progression of neurodegenerative disorders, this article provides an overview of the intrinsic power of the redox proteomics approach together with the most significant results obtained by our laboratory and others during almost 10 years of research on neurodegenerative disorders since we initiated the field of redox proteomics. Antioxid. Redox Signal. 17, 1610–1655. PMID:22115501

Measurement of diffusion coefficient of propylene glycol in skin tissue

NASA Astrophysics Data System (ADS)

Genin, Vadim D.; Bashkatov, Alexey N.; Genina, Elina A.; Tuchin, Valery V.

2015-03-01

Optical clearing of the rat skin under the action of propylene glycol was studied ex vivo. It was found that collimated transmittance of skin samples increased, whereas weight and thickness of the samples decreased during propylene glycol penetration in skin tissue. A mechanism of the optical clearing under the action of propylene glycol is discussed. Diffusion coefficient of propylene glycol in skin tissue ex vivo has been estimated as (1.35±0.95)×10-7 cm2/s with the taking into account of kinetics of both weight and thickness of skin samples. The presented results can be useful for enhancement of many methods of laser therapy and optical diagnostics of skin diseases and localization of subcutaneous neoplasms.

Ethylene Glycol-Induced Alteration of Conidial Germination in Neurospora crassa

PubMed Central

Bates, W. K.; Wilson, J. F.

1974-01-01

In nutrient medium containing 3.22 M ethylene glycol or glycerol, conidia of Neurospora crassa grow as single cells, without forming the germ tubes characteristic of normal morphological germination. Ethylene glycol is more effective than glycerol in producing this response. After growth in ethylene glycol medium for a suitable time, the cells are easily disrupted by an abrupt decrease in osmotic pressure. Osmotic disruption yields intact nuclei and mitochondria, although mitochondrial fractions obtained in this way show significantly reduced concentrations of cytochromes c + c1, as compared to those observed for comparable fractions obtained from vegetative hyphae. Cell cultures gradually adapted to lower concentrations of the glycol show a much higher degree of synchrony in the formation of germ tubes than do untreated conidia. Images PMID:4359649

Organic Acids: The Pools of Fixed Carbon Involved in Redox Regulation and Energy Balance in Higher Plants

PubMed Central

Igamberdiev, Abir U.; Eprintsev, Alexander T.

2016-01-01

Organic acids are synthesized in plants as a result of the incomplete oxidation of photosynthetic products and represent the stored pools of fixed carbon accumulated due to different transient times of conversion of carbon compounds in metabolic pathways. When redox level in the cell increases, e.g., in conditions of active photosynthesis, the tricarboxylic acid (TCA) cycle in mitochondria is transformed to a partial cycle supplying citrate for the synthesis of 2-oxoglutarate and glutamate (citrate valve), while malate is accumulated and participates in the redox balance in different cell compartments (via malate valve). This results in malate and citrate frequently being the most accumulated acids in plants. However, the intensity of reactions linked to the conversion of these compounds can cause preferential accumulation of other organic acids, e.g., fumarate or isocitrate, in higher concentrations than malate and citrate. The secondary reactions, associated with the central metabolic pathways, in particularly with the TCA cycle, result in accumulation of other organic acids that are derived from the intermediates of the cycle. They form the additional pools of fixed carbon and stabilize the TCA cycle. Trans-aconitate is formed from citrate or cis-aconitate, accumulation of hydroxycitrate can be linked to metabolism of 2-oxoglutarate, while 4-hydroxy-2-oxoglutarate can be formed from pyruvate and glyoxylate. Glyoxylate, a product of either glycolate oxidase or isocitrate lyase, can be converted to oxalate. Malonate is accumulated at high concentrations in legume plants. Organic acids play a role in plants in providing redox equilibrium, supporting ionic gradients on membranes, and acidification of the extracellular medium. PMID:27471516

76 FR 38026 - Diethylene Glycol Mono Butyl Ether; Exemption From the Requirement of a Tolerance

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-29

... chemicals. Immunotoxicity studies were available for ethylene glycol mono butyl ether, also a glycol ether... the glycol ether class of chemicals which include structurally similar chemicals ethylene glycol and... potential to cause cancer. Based on the lack of evidence of carcinogenicity potential for ethylene glycol...

Rate of Glycolate Formation During Photosynthesis at High pH 1

PubMed Central

Orth, Gertrude M.; Tolbert, N. E.; Jimenez, Eduardo

1966-01-01

The products of C14O2 fixation by Chlamydomonas and Chlorella were studied under conditions most favorable for glycolate synthesis. The highest percentage of the C14 was incorporated into glycolate in the pH range of 8 to 9. After 1 to 2 minutes as much as 40% of the C14 was found in glycolate products and only a trace of C14 was present as phosphoglycerate. Below pH 8 the rate of photosynthesis was much faster, but only a small percent of the C14 was incorporated into glycolate in 1 or 2 minutes, while a high percent of the C14 accumulated in phosphoglycerate. C14 labeling of glycolate even at pH 8 or above did not occur at times shorter than 10 seconds. During the first seconds of photosynthesis, nearly all of the C14 was found in phosphoglycerate and sugar phosphates. Thus glycolate appears to be formed after the phosphate esters of the photosynthetic carbon cycle. Washing Chlamydomonas with water 2 or 3 times resulted in the loss of most of their free phosphate. When a small aliquot of NaHC14O3 was added to washed algae in the absence of this buffering capacity, the pH of the algal medium became 8 or above and much of the fixed C14 accumulated in glycolate. PMID:16656223

Redox Biology in Neurological Function, Dysfunction, and Aging.

PubMed

Franco, Rodrigo; Vargas, Marcelo R

2018-04-23

Reduction oxidation (redox) reactions are central to life and when altered, they can promote disease progression. In the brain, redox homeostasis is recognized to be involved in all aspects of central nervous system (CNS) development, function, aging, and disease. Recent studies have uncovered the diverse nature by which redox reactions and homeostasis contribute to brain physiology, and when dysregulated to pathological consequences. Redox reactions go beyond what is commonly described as oxidative stress and involve redox mechanisms linked to signaling and metabolism. In contrast to the nonspecific nature of oxidative damage, redox signaling involves specific oxidation/reduction reactions that regulate a myriad of neurological processes such as neurotransmission, homeostasis, and degeneration. This Forum is focused on the role of redox metabolism and signaling in the brain. Six review articles from leading scientists in the field that appraise the role of redox metabolism and signaling in different aspects of brain biology including neurodevelopment, neurotransmission, aging, neuroinflammation, neurodegeneration, and neurotoxicity are included. An original research article exemplifying these concepts uncovers a novel link between oxidative modifications, redox signaling, and neurodegeneration. This Forum highlights the recent advances in the field and we hope it encourages future research aimed to understand the mechanisms by which redox metabolism and signaling regulate CNS physiology and pathophysiology. Antioxid. Redox Signal. 00, 000-000.

Improving metabolic efficiency of the reverse beta-oxidation cycle by balancing redox cofactor requirement.

PubMed

Wu, Junjun; Zhang, Xia; Zhou, Peng; Huang, Jiaying; Xia, Xiudong; Li, Wei; Zhou, Ziyu; Chen, Yue; Liu, Yinghao; Dong, Mingsheng

2017-11-01

Previous studies have made many exciting achievements on pushing the functional reversal of beta-oxidation cycle (r-BOX) to more widespread adoption for synthesis of a wide variety of fuels and chemicals. However, the redox cofactor requirement for the efficient operation of r-BOX remains unclear. In this work, the metabolic efficiency of r-BOX for medium-chain fatty acid (C 6 -C 10 , MCFA) production was optimized by redox cofactor engineering. Stoichiometric analysis of the r-BOX pathway and further experimental examination identified NADH as a crucial determinant of r-BOX process yield. Furthermore, the introduction of formate dehydrogenase from Candida boidinii using fermentative inhibitor byproduct formate as a redox NADH sink improved MCFA titer from initial 1.2g/L to 3.1g/L. Moreover, coupling of increasing the supply of acetyl-CoA with NADH to achieve fermentative redox balance enabled product synthesis at maximum titers. To this end, the acetate re-assimilation pathway was further optimized to increase acetyl-CoA availability associated with the new supply of NADH. It was found that the acetyl-CoA synthetase activity and intracellular ATP levels constrained the activity of acetate re-assimilation pathway, and 4.7g/L of MCFA titer was finally achieved after alleviating these two limiting factors. To the best of our knowledge, this represented the highest titer reported to date. These results demonstrated that the key constraint of r-BOX was redox imbalance and redox engineering could further unleash the lipogenic potential of this cycle. The redox engineering strategies could be applied to acetyl-CoA-derived products or other bio-products requiring multiple redox cofactors for biosynthesis. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

An evaluation of microbial growth and corrosion of 316L SS in glycol/seawater mixtures

NASA Technical Reports Server (NTRS)

Lee, Jason S.; Ray, Richard I.; Lowe, Kristine L.; Jones-Meehan, Joanne; Little, Brenda J.

2003-01-01

Glycol/seawater mixtures containing > 50% glycol inhibit corrosion of 316L stainless steel and do not support bacterial growth. The results indicate bacteria are able to use low concentrations of glycol (10%) as a growth medium, but bacterial growth decreased with increasing glycol concentration. Pitting potential, determined by anodic polarization, was used to evaluate susceptibility of 316L SS to corrosion in seawater-contaminated glycol. Mixture containing a minimum concentration of 50% propylene glycol-based coolant inhibited pitting corrosion. A slightly higher minimum concentration (55%) was needed for corrosion protection in ethylene glycol mixtures.

Cementitious building material incorporating end-capped polyethylene glycol as a phase change material

DOEpatents

Salyer, Ival O.; Griffen, Charles W.

1986-01-01

A cementitious composition comprising a cementitious material and polyethylene glycol or end-capped polyethylene glycol as a phase change material, said polyethylene glycol and said end-capped polyethylene glycol having a molecular weight greater than about 400 and a heat of fusion greater than about 30 cal/g; the compositions are useful in making pre-formed building materials such as concrete blocks, brick, dry wall and the like or in making poured structures such as walls or floor pads; the glycols can be encapsulated to reduce their tendency to retard set.

21 CFR 500.50 - Propylene glycol in or on cat food.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Propylene glycol in or on cat food. 500.50 Section... Propylene glycol in or on cat food. The Food and Drug Administration has determined that propylene glycol in or on cat food is not generally recognized as safe and is a food additive subject to section 409 of...

21 CFR 500.50 - Propylene glycol in or on cat food.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Propylene glycol in or on cat food. 500.50 Section... Propylene glycol in or on cat food. The Food and Drug Administration has determined that propylene glycol in or on cat food is not generally recognized as safe and is a food additive subject to section 409 of...

Organelle redox autonomy during environmental stress.

PubMed

Bratt, Avishay; Rosenwasser, Shilo; Meyer, Andreas; Fluhr, Robert

2016-09-01

Oxidative stress is generated in plants because of inequalities in the rate of reactive oxygen species (ROS) generation and scavenging. The subcellular redox state under various stress conditions was assessed using the redox reporter roGFP2 targeted to chloroplastic, mitochondrial, peroxisomal and cytosolic compartments. In parallel, the vitality of the plant was measured by ion leakage. Our results revealed that during certain physiological stress conditions the changes in roGFP2 oxidation are comparable to application of high concentrations of exogenous H2 O2 . Under each stress, particular organelles were affected. Conditions of extended dark stress, or application of elicitor, impacted chiefly on the status of peroxisomal redox state. In contrast, conditions of drought or high light altered the status of mitochondrial or chloroplast redox state, respectively. Amalgamation of the results from diverse environmental stresses shows cases of organelle autonomy as well as multi-organelle oxidative change. Importantly, organelle-specific oxidation under several stresses proceeded cell death as measured by ion leakage, suggesting early roGFP oxidation as predictive of cell death. The measurement of redox state in multiple compartments enables one to look at redox state connectivity between organelles in relation to oxidative stress as well as assign a redox fingerprint to various types of stress conditions. © 2016 John Wiley & Sons Ltd.

Hydrodynamic Microgap Voltammetry under Couette Flow Conditions: Electrochemistry at a Rotating Drum in Viscous Poly(ethylene glycol).

PubMed

Hotchen, Christopher E; Nguyen, H Viet; Fisher, Adrian C; Frith, Paul E; Marken, Frank

2015-07-21

Electrochemical processes in highly viscous media such as poly(ethylene glycol) (herein PEG200) are interesting for energy-conversion applications, but problematic due to slow diffusion causing low current densities. Here, a hydrodynamic microgap experiment based on Couette flow is introduced for an inlaid disc electrode approaching a rotating drum. Steady-state voltammetric currents are independent of viscosity and readily increased by two orders of magnitude with further potential to go to higher rotation rates and nanogaps. A quantitative theory is derived for the prediction of currents under high-shear Couette flow conditions and generalised for different electrode shapes. The 1,1'-ferrocene dimethanol redox probe in PEG200 (D=1.4×10 -11  m 2  s -1 ) is employed and data are compared with 1) a Levich-type equation expressing the diffusion-convection-limited current and 2) a COMSOL simulation model providing a potential-dependent current trace. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Redox-Active vs Redox-Innocent: A Comparison of Uranium Complexes Containing Diamine Ligands.

PubMed

Pattenaude, Scott A; Mullane, Kimberly C; Schelter, Eric J; Ferrier, Maryline G; Stein, Benjamin W; Bone, Sharon E; Lezama Pacheco, Juan S; Kozimor, Stosh A; Fanwick, Phillip E; Zeller, Matthias; Bart, Suzanne C

2018-05-11

Uranium complexes ( Mes DAE) 2 U(THF) (1-DAE) and Cp 2 U( Mes DAE) (2-DAE) ( Mes DAE = [ArN-CH 2 CH 2 -NAr]; Ar = 2,4,6-trimethylphenyl (Mes)), bearing redox-innocent diamide ligands, have been synthesized and characterized for a full comparison with previously published, redox-active diimine complexes, ( Mes DAB Me ) 2 U(THF) (1-DAB) and Cp 2 U( Mes DAB Me ) (2-DAB) ( Mes DAB Me = [ArN═C(Me)C(Me)═NAr]; Ar = Mes). These redox-innocent analogues maintain an analogous steric environment to their redox-active ligand counterparts to facilitate a study aimed at determining the differing electronic behavior around the uranium center. Structural analysis by X-ray crystallography showed 1-DAE and 2-DAE have a structural environment very similar to 1-DAB and 2-DAB, respectively. The main difference occurs with coordination of the ene-backbone to the uranium center in the latter species. Electronic absorption spectroscopy reveals these new DAE complexes are nearly identical to each other. X-ray absorption spectroscopy suggests all four species contain +4 uranium ions. The data also indicates that there is an electronic difference between the bis(diamide)-THF uranium complexes as opposed to those that only contain one diamide and two cyclopentadienyl rings. Finally, magnetic measurements reveal that all complexes display temperature-dependent behavior consistent with uranium(IV) ions that do not include ligand radicals. Overall, this study determines that there is no significant bonding difference between the redox-innocent and redox-active ligand frameworks on uranium. Furthermore, there are no data to suggest covalent bonding character using the latter ligand framework on uranium, despite what is known for transition metals.

A new low-volume isosmotic polyethylene glycol solution plus bisacodyl versus split-dose 4 L polyethylene glycol for bowel cleansing prior to colonoscopy: a randomised controlled trial.

PubMed

Cesaro, Paola; Hassan, Cesare; Spada, Cristiano; Petruzziello, Lucio; Vitale, Giovanna; Costamagna, Guido

2013-01-01

4-L polyethylene glycol preparations are effective for colon cleansing before colonoscopy. However, large volume and unpleasant taste reduce tolerability and acceptability limiting patient compliance. A new isosmotic low-volume polyethylene glycol preparation with citrates and simethicone plus bisacodyl has been developed to improve patient compliance and tolerability. To compare the efficacy of 2 different regimens of preparation vs a split-dose of polyethylene glycol solution. In this randomised, blinded, comparative study, 153 patients were allocated to 3 arms. Arm 1 (n=52) received bisacodyl and 2-L polyethylene glycol with citrates and simethicone the day before the procedure. Arm 2 (n=50) received bisacodyl the day before and 2-L polyethylene glycol with citrates and simethicone on the day of colonoscopy. Control group (n=51) received a split-dose of 4-L polyethylene glycol. Cleansing was evaluated according to Ottawa scale. The mean Ottawa score was not different in the 3 groups. Excellent cleansing was observed more frequently in arm 2 (70%) than in controls (49%) (p<0.05). No serious adverse events were observed in the 3 regimens. The willingness to repeat the same bowel preparation was superior in arms 1 and 2 than in controls (p<0.001). New low-volume preparations seem to be as effective as the split 4-L polyethylene glycol regimen, showing a better tolerability and acceptability. Copyright © 2012. Published by Elsevier Ltd.

Engineered Proteins: Redox Properties and Their Applications

PubMed Central

Prabhulkar, Shradha; Tian, Hui; Wang, Xiaotang; Zhu, Jun-Jie

2012-01-01

Abstract Oxidoreductases and metalloproteins, representing more than one third of all known proteins, serve as significant catalysts for numerous biological processes that involve electron transfers such as photosynthesis, respiration, metabolism, and molecular signaling. The functional properties of the oxidoreductases/metalloproteins are determined by the nature of their redox centers. Protein engineering is a powerful approach that is used to incorporate biological and abiological redox cofactors as well as novel enzymes and redox proteins with predictable structures and desirable functions for important biological and chemical applications. The methods of protein engineering, mainly rational design, directed evolution, protein surface modifications, and domain shuffling, have allowed the creation and study of a number of redox proteins. This review presents a selection of engineered redox proteins achieved through these methods, resulting in a manipulation in redox potentials, an increase in electron-transfer efficiency, and an expansion of native proteins by de novo design. Such engineered/modified redox proteins with desired properties have led to a broad spectrum of practical applications, ranging from biosensors, biofuel cells, to pharmaceuticals and hybrid catalysis. Glucose biosensors are one of the most successful products in enzyme electrochemistry, with reconstituted glucose oxidase achieving effective electrical communication with the sensor electrode; direct electron-transfer-type biofuel cells are developed to avoid thermodynamic loss and mediator leakage; and fusion proteins of P450s and redox partners make the biocatalytic generation of drug metabolites possible. In summary, this review includes the properties and applications of the engineered redox proteins as well as their significance and great potential in the exploration of bioelectrochemical sensing devices. Antioxid. Redox Signal. 17, 1796–1822. PMID:22435347

Redox-Active Separators for Lithium-Ion Batteries.

PubMed

Wang, Zhaohui; Pan, Ruijun; Ruan, Changqing; Edström, Kristina; Strømme, Maria; Nyholm, Leif

2018-03-01

A bilayered cellulose-based separator design is presented that can enhance the electrochemical performance of lithium-ion batteries (LIBs) via the inclusion of a porous redox-active layer. The proposed flexible redox-active separator consists of a mesoporous, insulating nanocellulose fiber layer that provides the necessary insulation between the electrodes and a porous, conductive, and redox-active polypyrrole-nanocellulose layer. The latter layer provides mechanical support to the nanocellulose layer and adds extra capacity to the LIBs. The redox-active separator is mechanically flexible, and no internal short circuits are observed during the operation of the LIBs, even when the redox-active layer is in direct contact with both electrodes in a symmetric lithium-lithium cell. By replacing a conventional polyethylene separator with a redox-active separator, the capacity of the proof-of-concept LIB battery containing a LiFePO 4 cathode and a Li metal anode can be increased from 0.16 to 0.276 mA h due to the capacity contribution from the redox-active separator. As the presented redox-active separator concept can be used to increase the capacities of electrochemical energy storage systems, this approach may pave the way for new types of functional separators.

Redox Pioneer: Professor Helmut Sies

PubMed Central

Radi, Rafael

2014-01-01

Abstract Professor Helmut Sies Dr. Helmut Sies (MD, 1967) is recognized as a Redox Pioneer, because he authored five articles on oxidative stress, lycopene, and glutathione, each of which has been cited more than 1000 times, and coauthored an article on hydroperoxide metabolism in mammalian systems cited more than 5000 times (Google Scholar). He obtained preclinical education at the University of Tübingen and the University of Munich, clinical training at Munich (MD, 1967) and Paris, and completed Habilitation at Munich (Physiological Chemistry and Physical Biochemistry, 1972). In early research, he first identified hydrogen peroxide (H2O2) as a normal aerobic metabolite and devised a method to quantify H2O2 concentration and turnover in cells. He quantified central redox systems for energy metabolism (NAD, NADP systems) and antioxidant GSH in subcellular compartments. He first described ebselen, a selenoorganic compound, as a glutathione peroxidase mimic. He contributed a fundamental discovery to the physiology of GSH, selenium nutrition, singlet oxygen biochemistry, and health benefits of dietary lycopene and cocoa flavonoids. He has published more than 600 articles, 134 of which are cited at least 100 times, and edited 28 books. His h-index is 115. During the last quarter of the 20th century and well into the 21st, he has served as a scout, trailblazer, and pioneer in redox biology. His formulation of the concept of oxidative stress stimulated and guided research in oxidants and antioxidants; his pioneering research on carotenoids and flavonoids informed nutritional strategies against cancer, cardiovascular disease, and aging; and his quantitative approach to redox biochemistry provides a foundation for modern redox systems biology. Helmut Sies is a true Redox Pioneer. Antioxid. Redox Signal. 21, 2459–2468. The joy of exploring the unknown and finding something novel and noteworthy: what a privilege! —Prof. Helmut Sies PMID:25178739

Single dose intratympanic mesna application inhibits propylene glycol induced cholesteatoma formation.

PubMed

Ismi, O; Karabulut, Y Y; Bal, K K; Vayisoglu, Y; Unal, M

2017-03-01

Mesna (i.e. sodium 2-mercaptoethanesulfonate; C2H5NaO3S2) has been used in otological surgery such as cholesteatoma dissection and tympanic membrane lateralisation in atelectatic ears. However, this study aimed to investigate its effect on cholesteatoma formation. A total of 20 Wistar rats were divided into two groups of 10 animals. The right and left ears of control animals were treated with saline (saline control group; n = 10 ears) and propylene glycol plus saline (propylene glycol control group; n = 10 ears), respectively. In the mesna group, both ears were treated with propylene glycol plus mesna (n = 20 ears). On days 1, 8 and 15, the saline control group had intratympanic injections of 0.2 ml saline and the propylene glycol control and mesna groups had intratympanic injections of 0.2 ml 100 per cent propylene glycol. On day 22, the propylene glycol control group had a single intratympanic injection of 0.2 ml saline and the mesna group had a single intratympanic injection of 10 per cent mesna. Animals were killed 12 weeks after the last injection and the temporal bones were sent for histopathological evaluation. The cholesteatoma formation rate was 88 per cent in the propylene glycol control group, but was significantly lower in the mesna group (p = 0.01). There were no significant differences in granulation tissue formation (p = 0.498), cyst formation in the bulla (p = 0.381), fibrosis (p = 0.072) and epithelial hyperplasia (p = 0.081) among experimental groups. Intratympanic propylene glycol administration is an effective method of promoting experimental cholesteatoma formation. Administration of a single dose of intratympanic mesna inhibited cholesteatoma formation in an animal model.

Comparison of Polyethylene Glycol-Electrolyte Solution vs Polyethylene Glycol-3350 for the Treatment of Fecal Impaction in Pediatric Patients

PubMed Central

Boles, Erin E.; Gaines, Cameryn L.

2015-01-01

OBJECTIVES: The objective of this study was to evaluate the safety and efficacy of polyethylene glycol-electrolyte solution vs polyethylene glycol-3350 for the treatment of fecal impaction in pediatric patients. METHODS: A retrospective, observational, institutional review board–approved study was conducted over a 1-year time period. Patients were included in the study if they were admitted to the hospital with a diagnosis of fecal impaction or constipation and were treated with either polyethylene glycol-electrolyte solution (PEG-ES) or polyethylene glycol-3350 (PEG-3350). Patients were excluded if they were discharged prior to resolution of treatment and/or did not receive PEG-ES or PEG-3350. RESULTS: Fifty-one patients (ranging in age from 1 month to 15 years) were evaluated: 23 patients received PEG-ES and 28 patients received PEG-3350. Sex, race, age, and weight were not statistically different between the 2 groups. Resolution of fecal impaction was not significantly different between PEG-ES vs PEG-3350 (87% and 86%, respectively; p = 0.87). There was only 1 reported side effect with PEG-3350, vs 11 reported side effects with PEG-ES (p < 0.01). CONCLUSIONS: Theses results suggest that PEG-3350 is as effective as PEG-ES for the treatment of fecal impaction in pediatric patients and is associated with fewer side effects. PMID:26170773

Development of Cy5.5-Labeled Hydrophobically Modified Glycol Chitosan Nanoparticles for Protein Delivery

NASA Astrophysics Data System (ADS)

Chin, Amanda

Therapeutic proteins are often highly susceptible to enzymatic degradation, thus restricting their in vivo stability. To overcome this limitation, delivery systems designed to promote uptake and reduce degradation kinetics have undergone a rapid shift from macro-scale systems to nanomaterial based carriers. Many of these nanomaterials, however, elicit immune responses and may have cytotoxic effects both in vitro and in vivo. The naturally derived polysaccharide chitosan has emerged as a promising biodegradable material and has been utilized for many biomedical applications; nevertheless, its function is often constrained by poor solubility. Glycol chitosan, a derivative of chitosan, can be hydrophobically modified to impart amphiphilic properties that enable the self-assembly into nanoparticles in aqueous media at neutral pH. This nanoparticle system has shown initial success as a therapeutic agent in several model cell culture systems, but little is known about its stability against enzymatic degradation. Therefore, the goal of this research was to investigate the resistance of hydrophobically modified glycol chitosan against enzyme-catalyzed degradation using an in vivo simulated system containing lysozyme. To synthesize the nanoparticles, hydrophobic cholanic acid was first covalently conjugated to glycol chitosan using of N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). Conjugates were purified by dialysis, lyophilized, and ultra-sonicated to form nanoparticles. Fourier transform infrared (FT-IR) spectroscopy confirmed the binding of 5beta-cholanic acid to the glycol chitosan. Particle size and stability over time were determined with dynamic light scattering (DLS), and particle morphology was evaluated by transmission electron microscopy (TEM). The average diameter of the nanoparticles was approximately 200 nm, which remained stable at 4°C for up to 10 days. Additionally, a near infrared fluorescent (NIRF) dye

Redox proteomics and drug development.

PubMed

D'Alessandro, Angelo; Rinalducci, Sara; Zolla, Lello

2011-11-18

As alterations of the redox homeostasis lie at the root of many pathophysiological processes in human health, redox proteomics holds the promise to shed further light on fundamental biological processes. In this review, the mechanisms of reactive oxygen species (ROS) and reactive nitrogen species (RNS) production are reviewed, mainly addressing those chemical phenomena which have already been associated with pathological conditions (of the central nervous system, cardiovascular system, or simply related to aging and altered-cell cycle regulation). From Alzheimer's to Parkinson's and Hungtinton's disease, from ageing to cancer, oxidative stress (OS) appears to represent a common trait in so many relevant biological aspects of human health, that further investments in the field of redox proteomics ought to be mandatory. For the foreseeable future, redox proteomics will likely play a pivotal role in the quest for new therapeutical targets and their validation, in the process of determining OS-triggered cellular alteration upon drug treatments and thus in the very heart of the design and testing of new drugs and their metabolites against those pathologies relying on altered redox homeostasis. Copyright © 2011 Elsevier B.V. All rights reserved.

Membrane permeability of the human granulocyte to water, dimethyl sulfoxide, glycerol, propylene glycol and ethylene glycol.

PubMed

Vian, Alex M; Higgins, Adam Z

2014-02-01

Granulocytes are currently transfused as soon as possible after collection because they rapidly deteriorate after being removed from the body. This short shelf life complicates the logistics of granulocyte collection, banking, and safety testing. Cryopreservation has the potential to significantly increase shelf life; however, cryopreservation of granulocytes has proven to be difficult. In this study, we investigate the membrane permeability properties of human granulocytes, with the ultimate goal of using membrane transport modeling to facilitate development of improved cryopreservation methods. We first measured the equilibrium volume of human granulocytes in a range of hypo- and hypertonic solutions and fit the resulting data using a Boyle-van't Hoff model. This yielded an isotonic cell volume of 378 μm(3) and an osmotically inactive volume of 165 μm(3). To determine the permeability of the granulocyte membrane to water and cryoprotectant (CPA), cells were injected into well-mixed CPA solution while collecting volume measurements using a Coulter Counter. These experiments were performed at temperatures ranging from 4 to 37°C for exposure to dimethyl sulfoxide, glycerol, ethylene glycol, and propylene glycol. The best-fit water permeability was similar in the presence of all of the CPAs, with an average value at 21°C of 0.18 μmatm(-1)min(-1). The activation energy for water transport ranged from 41 to 61 kJ/mol. The CPA permeability at 21°C was 6.4, 1.0, 8.4, and 4.0 μm/min for dimethyl sulfoxide, glycerol, ethylene glycol, and propylene glycol, respectively, and the activation energy for CPA transport ranged between 59 and 68 kJ/mol. Copyright © 2013 Elsevier Inc. All rights reserved.

Simultaneous anionic and cationic redox

NASA Astrophysics Data System (ADS)

Jung, Sung-Kyun; Kang, Kisuk

2017-12-01

It is challenging to unlock anionic redox activity, accompanied by full utilization of available cationic redox process, to boost capacity of battery cathodes. Now, material design by tuning the metal-oxygen interaction is shown to be a promising solution.

Membranes for redox flow battery applications.

PubMed

Prifti, Helen; Parasuraman, Aishwarya; Winardi, Suminto; Lim, Tuti Mariana; Skyllas-Kazacos, Maria

2012-06-19

The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. The membrane acts as a separator to prevent cross-mixing of the positive and negative electrolytes, while still allowing the transport of ions to complete the circuit during the passage of current. An ideal membrane should have high ionic conductivity, low water intake and excellent chemical and thermal stability as well as good ionic exchange capacity. Developing a low cost, chemically stable membrane for redox flow cell batteries has been a major focus for many groups around the world in recent years. This paper reviews the research work on membranes for redox flow batteries, in particular for the all-vanadium redox flow battery which has received the most attention.

Membranes for Redox Flow Battery Applications

PubMed Central

Prifti, Helen; Parasuraman, Aishwarya; Winardi, Suminto; Lim, Tuti Mariana; Skyllas-Kazacos, Maria

2012-01-01

The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. The membrane acts as a separator to prevent cross-mixing of the positive and negative electrolytes, while still allowing the transport of ions to complete the circuit during the passage of current. An ideal membrane should have high ionic conductivity, low water intake and excellent chemical and thermal stability as well as good ionic exchange capacity. Developing a low cost, chemically stable membrane for redox flow cell batteries has been a major focus for many groups around the world in recent years. This paper reviews the research work on membranes for redox flow batteries, in particular for the all-vanadium redox flow battery which has received the most attention. PMID:24958177

Dual redox catalysts for oxygen reduction and evolution reactions: towards a redox flow Li-O2 battery.

PubMed

Zhu, Yun Guang; Jia, Chuankun; Yang, Jing; Pan, Feng; Huang, Qizhao; Wang, Qing

2015-06-11

A redox flow lithium-oxygen battery (RFLOB) by using soluble redox catalysts with good performance was demonstrated for large-scale energy storage. The new device enables the reversible formation and decomposition of Li2O2 via redox targeting reactions in a gas diffusion tank, spatially separated from the electrode, which obviates the passivation and pore clogging of the cathode.

Anaerobic ethylene glycol degradation by microorganisms in poplar and willow rhizospheres.

PubMed

Carnegie, D; Ramsay, J A

2009-07-01

Although aerobic degradation of ethylene glycol is well documented, only anaerobic biodegradation via methanogenesis or fermentation has been clearly shown. Enhanced ethylene glycol degradation has been demonstrated by microorganisms in the rhizosphere of shallow-rooted plants such as alfalfa and grasses where conditions may be aerobic, but has not been demonstrated in the deeper rhizosphere of poplar or willow trees where conditions are more likely to be anaerobic. This study evaluated ethylene glycol degradation under nitrate-, and sulphate-reducing conditions by microorganisms from the rhizosphere of poplar and willow trees planted in the path of a groundwater plume containing up to 1.9 mol l(-1) (120 g l(-1)) ethylene glycol and, the effect of fertilizer addition when nitrate or sulphate was provided as a terminal electron acceptor (TEA). Microorganisms in these rhizosphere soils degraded ethylene glycol using nitrate or sulphate as TEAs at close to the theoretical stoichiometric amounts required for mineralization. Although the added nitrate or sulphate was primarily used as TEA, TEAs naturally present in the soil or CO(2) produced from ethylene glycol degradation were also used, demonstrating multiple TEA usage. Anaerobic degradation produced acetaldehyde, less acetic acid, and more ethanol than under aerobic conditions. Although aerobic degradation rates were faster, close to 100% disappearance was eventually achieved anaerobically. Degradation rates under nitrate-reducing conditions were enhanced upon fertilizer addition to achieve rates similar to aerobic degradation with up to 19.3 mmol (1.20 g) of ethylene glycol degradation l(-1) day(-1) in poplar soils. This is the first study to demonstrate that microorganisms in the rhizosphere of deep rooted trees like willow and poplar can anaerobically degrade ethylene glycol. Since anaerobic biodegradation may significantly contribute to the phytoremediation of ethylene glycol in the deeper subsurface, the need

Oxidative stress, thiols, and redox profiles.

PubMed

Harris, Craig; Hansen, Jason M

2012-01-01

Oxidative stress has been recognized as a contributing factor in the toxicity of a large number of developmental toxicants. Traditional definitions of oxidative stress state that a shift in the balance between reduced and oxidized biomolecules within cells, in favor of the latter, result in changes that are deleterious to vital cell functions and can culminate in malformations and death. The glutathione (GSH)/glutathione disulfide (GSSG) redox couple has been the traditional marker of choice for characterization of oxidative stress because of its high concentrations and direct roles as antioxidant and cellular protectant. Steady state depletion of GSH through conjugation, oxidation, or export has often been reported as the sole criteria for invoking oxidative stress and a myriad of associated deleterious consequences. Numerous other, mostly qualitative, observations have also been reported to suggest oxidative stress has occurred but it is not always clear how well they reflect the state of a cell or its functions. Our emerging understanding of redox signaling and the roles of reactive oxygen species (ROS), thiols, oxidant molecules, and cellular antioxidants, all acting as second messengers, has prompted a redefinition of oxidative stress based on changes in the real posttranslational protein thiol modifications that are central to redox regulation and control. Thiol-based redox couples such as GSH/GSSG, cysteine/cystine (cys/cySS), thioredoxin-reduced/thioredoxin-oxidized (TRX(red)/TRX(ox)) form independent signaling nodes that selectively regulate developmental events and are closely linked to changes in intracellular redox potentials. Accurate assessment of the consequences of increased free radicals in developing conceptuses should best be made using a battery of measurements including the quantitative assessment of intracellular redox potential, ROS, redox status of biomolecules, and induced changes in specific redox signaling nodes. Methods are presented for

21 CFR 172.820 - Polyethylene glycol (mean molecular weight 200-9,500).

Code of Federal Regulations, 2010 CFR

2010-04-01

... ethylene oxide and water with a mean molecular weight of 200 to 9,500. (2) It contains no more than 0.2 percent total by weight of ethylene and diethylene glycols when tested by the analytical methods... the total ethylene and diethylene glycol content of polyethylene glycols having mean molecular weights...

Thiol/disulfide redox states in signaling and sensing

PubMed Central

Go, Young-Mi; Jones, Dean P.

2015-01-01

Rapid advances in redox systems biology are creating new opportunities to understand complexities of human disease and contributions of environmental exposures. New understanding of thiol-disulfide systems have occurred during the past decade as a consequence of the discoveries that thiol and disulfide systems are maintained in kinetically controlled steady-states displaced from thermodynamic equilibrium, that a widely distributed family of NADPH oxidases produces oxidants that function in cell signaling, and that a family of peroxiredoxins utilize thioredoxin as a reductant to complement the well-studied glutathione antioxidant system for peroxide elimination and redox regulation. This review focuses on thiol/disulfide redox state in biologic systems and the knowledge base available to support development of integrated redox systems biology models to better understand the function and dysfunction of thiol-disulfide redox systems. In particular, central principles have emerged concerning redox compartmentalization and utility of thiol/disulfide redox measures as indicators of physiologic function. Advances in redox proteomics show that, in addition to functioning in protein active sites and cell signaling, cysteine residues also serve as redox sensors to integrate biologic functions. These advances provide a framework for translation of redox systems biology concepts to practical use in understanding and treating human disease. Biological responses to cadmium, a widespread environmental agent, are used to illustrate the utility of these advances to the understanding of complex pleiotropic toxicities. PMID:23356510

Screening of redox couples and electrode materials

NASA Technical Reports Server (NTRS)

Giner, J.; Swette, L.; Cahill, K.

1976-01-01

Electrochemical parameters of selected redox couples that might be potentially promising for application in bulk energy storage systems were investigated. This was carried out in two phases: a broad investigation of the basic characteristics and behavior of various redox couples, followed by a more limited investigation of their electrochemical performance in a redox flow reactor configuration. In the first phase of the program, eight redox couples were evaluated under a variety of conditions in terms of their exchange current densities as measured by the rotating disk electrode procedure. The second phase of the program involved the testing of four couples in a redox reactor under flow conditions with a varity of electrode materials and structures.

Determination of glycols in air: development of sampling and analytical methodology and application to theatrical smokes.

PubMed

Pendergrass, S M

1999-01-01

Glycol-based fluids are used in the production of theatrical smokes in theaters, concerts, and other stage productions. The fluids are heated and dispersed in aerosol form to create the effect of a smoke, mist, or fog. There have been reports of adverse health effects such as respiratory irritation, chest tightness, shortness of breath, asthma, and skin rashes. Previous attempts to collect and quantify the aerosolized glycols used in fogging agents have been plagued by inconsistent results, both in the efficiency of collection and in the chromatographic analysis of the glycol components. The development of improved sampling and analytical methodology for aerosolized glycols was required to assess workplace exposures more effectively. An Occupational Safety and Health Administration versatile sampler tube was selected for the collection of ethylene glycol, propylene glycol, 1,3-butylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol aerosols. Analytical methodology for the separation, identification, and quantitation of the six glycols using gas chromatography/flame ionization detection is described. Limits of detection of the glycol analytes ranged from 7 to 16 micrograms/sample. Desorption efficiencies for all glycol compounds were determined over the range of study and averaged greater than 90%. Storage stability results were acceptable after 28 days for all analytes except ethylene glycol, which was stable at ambient temperature for 14 days. Based on the results of this study, the new glycol method was published in the NIOSH Manual of Analytical Methods.

Preparation and characterization of PVDF separators for lithium ion cells using hydroxyl-terminated polybutadiene grafted methoxyl polyethylene glycol (HTPB-g-MPEG) as additive

NASA Astrophysics Data System (ADS)

Li, Hao; Niu, Dong-Hui; Zhou, Hui; Chao, Chun-Ying; Wu, Li-Jun; Han, Pei-Lin

2018-05-01

Hydroxyl-terminated polybutadiene grafted methoxyl polyethylene glycol (HTPB-g-MPEG) with different arm length were synthesized by grafting methoxyl poly(ethylene glycol)s (MPEGs, Mn = 350, 750, 1900 and 5000, respectively) to the hydroxyl-terminated polybutadiene (HTPB) molecule using isophorone diisocyanate (IPDI) as the coupling agent, and blended with PVDF to fabricate porous separators via phase inversion process. By measuring the composition, morphology and ion conductivity etc., the influence of HTPB-g-MPEG on structure and property of blend separators were discussed. Compared with pure PVDF separator with comparable porous structure, the adoption of HTPB-g-MPEG could not only decrease the crystallinity, but also enhance the stability of entrapped liquid electrolyte and corresponding ion conductivity. The cells assembled with such separators showed good initial discharge capacity and cyclic stability.

Redox biology response in germinating Phaseolus vulgaris seeds exposed to copper: Evidence for differential redox buffering in seedlings and cotyledon.

PubMed

Karmous, Inès; Trevisan, Rafael; El Ferjani, Ezzeddine; Chaoui, Abdelilah; Sheehan, David

2017-01-01

In agriculture, heavy metal contamination of soil interferes with processes associated with plant growth, development and productivity. Here, we describe oxidative and redox changes, and deleterious injury within cotyledons and seedlings caused by exposure of germinating (Phaseolus vulgaris L. var. soisson nain hâtif) seeds to copper (Cu). Cu induced a marked delay in seedling growth, and was associated with biochemical disturbances in terms of intracellular oxidative status, redox regulation and energy metabolism. In response to these alterations, modulation of activities of antioxidant proteins (thioredoxin and glutathione reductase, peroxiredoxin) occurred, thus preventing oxidative damage. In addition, oxidative modification of proteins was detected in both cotyledons and seedlings by one- and two-dimensional electrophoresis. These modified proteins may play roles in redox buffering. The changes in activities of redox proteins underline their fundamental roles in controlling redox homeostasis. However, observed differential redox responses in cotyledon and seedling tissues showed a major capacity of the seedlings' redox systems to protect the reduced status of protein thiols, thus suggesting quantitatively greater antioxidant protection of proteins in seedlings compared to cotyledon. To our knowledge, this is the first comprehensive redox biology investigation of the effect of Cu on seed germination.

Rapid and Efficient Redox Processes within 2D Covalent Organic Framework Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeBlase, Catherine R.; Hernández-Burgos, Kenneth; Silberstein, Katharine E.

2015-03-24

Two-dimensional covalent organic frameworks (2D COFs) are ideally suited for organizing redox-active subunits into periodic, permanently porous polymer networks of interest for pseudocapacitive energy storage. Here we describe a method for synthesizing crystalline, oriented thin films of a redox-active 2D COF on Au working electrodes. The thickness of the COF film was controlled by varying the initial monomer concentration. A large percentage (80–99%) of the anthraquinone groups are electrochemically accessible in films thinner than 200 nm, an order of magnitude improvement over the same COF prepared as a randomly oriented microcrystalline powder. As a result, electrodes functionalized with oriented COFmore » films exhibit a 400% increase in capacitance scaled to electrode area as compared to those functionalized with the randomly oriented COF powder. These results demonstrate the promise of redox-active COFs for electrical energy storage and highlight the importance of controlling morphology for optimal performance.« less

Rapid and Efficient Redox Processes within 2D Covalent Organic Framework Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeBlase, Catherine R.; Hernández-Burgos, Kenneth; Silberstein, Katharine E.

2015-02-17

Two-dimensional covalent organic frameworks (2D COFs) are ideally suited for organizing redox-active subunits into periodic, permanently porous polymer networks of interest for pseudocapacitive energy storage. Here we describe a method for synthesizing crystalline, oriented thin films of a redox-active 2D COF on Au working electrodes. The thickness of the COF film was controlled by varying the initial monomer concentration. A large percentage (80–99%) of the anthraquinone groups are electrochemically accessible in films thinner than 200 nm, an order of magnitude improvement over the same COF prepared as a randomly oriented microcrystalline powder. As a result, electrodes functionalized with oriented COFmore » films exhibit a 400% increase in capacitance scaled to electrode area as compared to those functionalized with the randomly oriented COF powder. These results demonstrate the promise of redox-active COFs for electrical energy storage and highlight the importance of controlling morphology for optimal performance.« less

Redox Regulation of Plant Development

PubMed Central

Considine, Michael J.

2014-01-01

Abstract Significance: We provide a conceptual framework for the interactions between the cellular redox signaling hub and the phytohormone signaling network that controls plant growth and development to maximize plant productivity under stress-free situations, while limiting growth and altering development on exposure to stress. Recent Advances: Enhanced cellular oxidation plays a key role in the regulation of plant growth and stress responses. Oxidative signals or cycles of oxidation and reduction are crucial for the alleviation of dormancy and quiescence, activating the cell cycle and triggering genetic and epigenetic control that underpin growth and differentiation responses to changing environmental conditions. Critical Issues: The redox signaling hub interfaces directly with the phytohormone network in the synergistic control of growth and its modulation in response to environmental stress, but a few components have been identified. Accumulating evidence points to a complex interplay of phytohormone and redox controls that operate at multiple levels. For simplicity, we focus here on redox-dependent processes that control root growth and development and bud burst. Future Directions: The multiple roles of reactive oxygen species in the control of plant growth and development have been identified, but increasing emphasis should now be placed on the functions of redox-regulated proteins, along with the central roles of reductants such as NAD(P)H, thioredoxins, glutathione, glutaredoxins, peroxiredoxins, ascorbate, and reduced ferredoxin in the regulation of the genetic and epigenetic factors that modulate the growth and vigor of crop plants, particularly within an agricultural context. Antioxid. Redox Signal. 21, 1305–1326. PMID:24180689

Redox homeostasis: The Golden Mean of healthy living

PubMed Central

Ursini, Fulvio; Maiorino, Matilde; Forman, Henry Jay

2016-01-01

The notion that electrophiles serve as messengers in cell signaling is now widely accepted. Nonetheless, major issues restrain acceptance of redox homeostasis and redox signaling as components of maintenance of a normal physiological steady state. The first is that redox signaling requires sudden switching on of oxidant production and bypassing of antioxidant mechanisms rather than a continuous process that, like other signaling mechanisms, can be smoothly turned up or down. The second is the misperception that reactions in redox signaling involve “reactive oxygen species” rather than reaction of specific electrophiles with specific protein thiolates. The third is that hormesis provides protection against oxidants by increasing cellular defense or repair mechanisms rather than by specifically addressing the offset of redox homeostasis. Instead, we propose that both oxidant and antioxidant signaling are main features of redox homeostasis. As the redox shift is rapidly reversed by feedback reactions, homeostasis is maintained by continuous signaling for production and elimination of electrophiles and nucleophiles. Redox homeostasis, which is the maintenance of nucleophilic tone, accounts for a healthy physiological steady state. Electrophiles and nucleophiles are not intrinsically harmful or protective, and redox homeostasis is an essential feature of both the response to challenges and subsequent feedback. While the balance between oxidants and nucleophiles is preserved in redox homeostasis, oxidative stress provokes the establishment of a new radically altered redox steady state. The popular belief that scavenging free radicals by antioxidants has a beneficial effect is wishful thinking. We propose, instead, that continuous feedback preserves nucleophilic tone and that this is supported by redox active nutritional phytochemicals. These nonessential compounds, by activating Nrf2, mimic the effect of endogenously produced electrophiles (parahormesis). In summary

Exercise redox biochemistry: Conceptual, methodological and technical recommendations.

PubMed

Cobley, James N; Close, Graeme L; Bailey, Damian M; Davison, Gareth W

2017-08-01

Exercise redox biochemistry is of considerable interest owing to its translational value in health and disease. However, unaddressed conceptual, methodological and technical issues complicate attempts to unravel how exercise alters redox homeostasis in health and disease. Conceptual issues relate to misunderstandings that arise when the chemical heterogeneity of redox biology is disregarded: which often complicates attempts to use redox-active compounds and assess redox signalling. Further, that oxidised macromolecule adduct levels reflect formation and repair is seldom considered. Methodological and technical issues relate to the use of out-dated assays and/or inappropriate sample preparation techniques that confound biochemical redox analysis. After considering each of the aforementioned issues, we outline how each issue can be resolved and provide a unifying set of recommendations. We specifically recommend that investigators: consider chemical heterogeneity, use redox-active compounds judiciously, abandon flawed assays, carefully prepare samples and assay buffers, consider repair/metabolism, use multiple biomarkers to assess oxidative damage and redox signalling. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Development of crosslinked methylcellulose hydrogels for soft tissue augmentation using an ammonium persulfate-ascorbic acid redox system.

PubMed

Gold, Gittel T; Varma, Devika M; Taub, Peter J; Nicoll, Steven B

2015-12-10

Hydrogels composed of methylcellulose are candidate materials for soft tissue reconstruction. Although photocrosslinked methylcellulose hydrogels have shown promise for such applications, gels crosslinked using reduction-oxidation (redox) initiators may be more clinically viable. In this study, methylcellulose modified with functional methacrylate groups was polymerized using an ammonium persulfate (APS)-ascorbic acid (AA) redox initiation system to produce injectable hydrogels with tunable properties. By varying macromer concentration from 2% to 4% (w/v), the equilibrium moduli of the hydrogels ranged from 1.47 ± 0.33 to 5.31 ± 0.71 kPa, on par with human adipose tissue. Gelation time was found to conform to the ISO standard for injectable materials. Cellulase treatment resulted in complete degradation of the hydrogels within 24h, providing a reversible corrective feature. Co-culture with human dermal fibroblasts confirmed the cytocompatibility of the gels based on DNA measurements and Live/Dead imaging. Taken together, this evidence indicates that APS-AA redox-polymerized methylcellulose hydrogels possess properties beneficial for use as soft tissue fillers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electrochemistry of redox-active self-assembled monolayers

PubMed Central

Eckermann, Amanda L.; Feld, Daniel J.; Shaw, Justine A.; Meade, Thomas J.

2010-01-01

Redox-active self-assembled monolayers (SAMs) provide an excellent platform for investigating electron transfer kinetics. Using a well-defined bridge, a redox center can be positioned at a fixed distance from the electrode and electron transfer kinetics probed using a variety of electrochemical techniques. Cyclic voltammetry, AC voltammetry, electrochemical impedance spectroscopy, and chronoamperometry are most commonly used to determine the rate of electron transfer of redox-activated SAMs. A variety of redox species have been attached to SAMs, and include transition metal complexes (e.g., ferrocene, ruthenium pentaammine, osmium bisbipyridine, metal clusters) and organic molecules (e.g., galvinol, C60). SAMs offer an ideal environment to study the outer-sphere interactions of redox species. The composition and integrity of the monolayer and the electrode material influence the electron transfer kinetics and can be investigated using electrochemical methods. Theoretical models have been developed for investigating SAM structure. This review discusses methods and monolayer compositions for electrochemical measurements of redox-active SAMs. PMID:20563297

Redox Bulk Energy Storage System Study, Volume 1

NASA Technical Reports Server (NTRS)

Ciprios, G.; Erskine, W., Jr.; Grimes, P. G.

1977-01-01

Opportunities were found for electrochemical energy storage devices in the U.S. electric utility industry. Application requirements for these devices were defined, including techno-economic factors. A new device, the Redox storage battery was analyzed. The Redox battery features a decoupling of energy storage and power conversion functions. General computer methods were developed to simulate Redox system operations. These studies showed that the Redox system is potentially attractive if certain performance goals can be achieved. Pathways for reducing the cost of the Redox system were identified.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zamecnik, J. R.; Edwards, T. B.

The conversions of nitrite to nitrate, the destruction of glycolate, and the conversion of glycolate to formate and oxalate were modeled for the Nitric-Glycolic flowsheet using data from Chemical Process Cell (CPC) simulant runs conducted by SRNL from 2011 to 2015. The goal of this work was to develop empirical correlations for these variables versus measureable variables from the chemical process so that these quantities could be predicted a-priori from the sludge composition and measurable processing variables. The need for these predictions arises from the need to predict the REDuction/OXidation (REDOX) state of the glass from the Defense Waste Processingmore » Facility (DWPF) melter. This report summarizes the initial work on these correlations based on the aforementioned data. Further refinement of the models as additional data is collected is recommended.« less

21 CFR 172.765 - Succistearin (stearoyl propylene glycol hydrogen succinate).

Code of Federal Regulations, 2010 CFR

2010-04-01

... HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Other Specific Usage Additives § 172.765 Succistearin (stearoyl propylene glycol hydrogen succinate). The food additive succistearin (stearoyl propylene glycol hydrogen...

Tuning the redox potential of vitamin K3 derivatives by oxidative functionalization using a Ag(i)/GO catalyst.

PubMed

El-Hout, S I; Suzuki, H; El-Sheikh, S M; Hassan, H M A; Harraz, F A; Ibrahim, I A; El-Sharkawy, E A; Tsujimura, S; Holzinger, M; Nishina, Y

2017-08-03

We propose herein initial results to develop optimum redox mediators by the combination of computational simulation and catalytic functionalization of the core structure of vitamin K 3 . We aim to correlate the calculated energy value of the LUMO of different vitamin K 3 derivatives with their actual redox potential. For this, we optimized the catalytic alkylation of 1,4-naphthoquinones with a designed Ag(i)/GO catalyst and synthesized a series of molecules.

Redox active polymers and colloidal particles for flow batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gavvalapalli, Nagarjuna; Moore, Jeffrey S.; Rodriguez-Lopez, Joaquin

The invention provides a redox flow battery comprising a microporous or nanoporous size-exclusion membrane, wherein one cell of the battery contains a redox-active polymer dissolved in the non-aqueous solvent or a redox-active colloidal particle dispersed in the non-aqueous solvent. The redox flow battery provides enhanced ionic conductivity across the electrolyte separator and reduced redox-active species crossover, thereby improving the performance and enabling widespread utilization. Redox active poly(vinylbenzyl ethylviologen) (RAPs) and redox active colloidal particles (RACs) were prepared and were found to be highly effective redox species. Controlled potential bulk electrolysis indicates that 94-99% of the nominal charge on different RAPsmore » is accessible and the electrolysis products are stable upon cycling. The high concentration attainable (>2.0 M) for RAPs in common non-aqueous battery solvents, their electrochemical and chemical reversibility, and their hindered transport across porous separators make them attractive materials for non-aqueous redox flow batteries based on size-selectivity.« less

[Determination of ethylene glycol in biological fluids--propylene glycol interferences].

PubMed

Gomółka, Ewa; Cudzich-Czop, Sylwia; Sulka, Adrianna

2013-01-01

Many laboratories in Poland do not use gas chromatography (GC) method for determination of ethylene glycol (EG) and methanol in blood of poisoned patients, they use non specific spectrophotometry methods. One of the interfering substances is propylene glycol (PG)--compound present in many medical and cosmetic products: drops, air freshens, disinfectants, electronic cigarettes and others. In Laboratory of Analytical Toxicology and Drug Monitoring in Krakow determination of EG is made by GC method. The method enables to distinguish and make resolution of (EG) and (PG) in biological samples. In the years 2011-2012 in several serum samples from diagnosed patients PG was present in concentration from several to higher than 100 mg/dL. The aim of the study was to estimate PG interferences of serum EG determination by spectrophotometry method. Serum samples containing PG and EG were used in the study. The samples were analyzed by two methods: GC and spectrophotometry. Results of serum samples spiked with PG with no EG analysed by spectrophotometry method were improper ("false positive"). The results were correlated to PG concentration in samples. Calculated cross-reactivity of PG in the method was 42%. Positive results of EG measured by spectrophotometry method must be confirmed by reference GC method. Spectrophotometry method shouldn't be used for diagnostics and monitoring of patients poisoned by EG.

Redox potentials and kinetics of the Ce 3+/Ce 4+ redox reaction and solubility of cerium sulfates in sulfuric acid solutions

NASA Astrophysics Data System (ADS)

Paulenova, A.; Creager, S. E.; Navratil, J. D.; Wei, Y.

Experimental work was performed with the aim of evaluating the Ce 4+/Ce 3+ redox couple in sulfuric acid electrolyte for use in redox flow battery (RFB) technology. The solubility of cerium sulfates in 0.1-4.0 M sulfuric acid at 20-60 °C was studied. A synergistic effect of both sulfuric acid concentration and temperature on the solubility of cerous sulfate was observed. The solubility of cerous sulfate significantly decreased with rising concentration of sulfuric acid and rising temperature, while the solubility of ceric sulfate goes through a significant maximum at 40 °C. Redox potentials and the kinetics of the cerous/ceric redox reaction were also studied under the same temperature-concentration conditions. The redox potentials were measured using the combined redox electrode (Pt-Ag/AgCl) in equimolar Ce 4+/Ce 3+ solutions (i.e.[Ce 3+]=[Ce 4+]) in sulfuric acid electrolyte. The Ce 3+/Ce 4+ redox potentials significantly decrease (i.e. shift to more negative values) with rising sulfuric acid concentration; a small maximum is observed at 40 °C. Cyclic voltammetric experiments confirmed slow electrochemical kinetics of the Ce 3+/Ce 4+ redox reaction on carbon glassy electrodes (CGEs) in sulfuric acid solutions. The observed dependencies of solubilities, the redox potentials and the kinetics of Ce 3+/Ce 4+ redox reaction on sulfuric acid concentration are thought to be the result of inequivalent complexation of the two redox species by sulfate anions: the ceric ion is much more strongly bound to sulfate than is the cerous ion. The best temperature-concentration conditions for the RFB electrolytes appear to be 40 °C and 1 M sulfuric acid, where the relatively good solubility of both cerium species, the maximum of redox potentials, and the more or less satisfying stability of CGE s were found. Even so, the relatively low solubility of cerium salts in sulfuric acid media and slow redox kinetics of the Ce 3+/Ce 4+ redox reaction at carbon indicate that the Ce 3+/Ce

Polyoxometalate active charge-transfer material for mediated redox flow battery

DOEpatents

Anderson, Travis Mark; Hudak, Nicholas; Staiger, Chad; Pratt, Harry

2017-01-17

Redox flow batteries including a half-cell electrode chamber coupled to a current collecting electrode are disclosed herein. In a general embodiment, a separator is coupled to the half-cell electrode chamber. The half-cell electrode chamber comprises a first redox-active mediator and a second redox-active mediator. The first redox-active mediator and the second redox-active mediator are circulated through the half-cell electrode chamber into an external container. The container includes an active charge-transfer material. The active charge-transfer material has a redox potential between a redox potential of the first redox-active mediator and a redox potential of the second redox-active mediator. The active charge-transfer material is a polyoxometalate or derivative thereof. The redox flow battery may be particularly useful in energy storage solutions for renewable energy sources and for providing sustained power to an electrical grid.

40 CFR 721.10546 - Pentenylated polyethylene glycol sulfate salt (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... sulfate salt (generic). 721.10546 Section 721.10546 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10546 Pentenylated polyethylene glycol sulfate salt... identified generically as pentenylated polyethylene glycol sulfate salt (PMN P-04-340) is subject to...

40 CFR 721.10546 - Pentenylated polyethylene glycol sulfate salt (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... sulfate salt (generic). 721.10546 Section 721.10546 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10546 Pentenylated polyethylene glycol sulfate salt... identified generically as pentenylated polyethylene glycol sulfate salt (PMN P-04-340) is subject to...

Analysis of the Properties of the Esters of Neopentyl Glycol,

DTIC Science & Technology

The esters of neopentyl glycol and monocarboxylic acids of normal and isomeric structure were synthesized. The esters are characterized by higher...indices of viscosity and solidification temperatures than the esters of the acids of isomeric structure. The esters of neopentyl glycol and industrial

40 CFR 721.3900 - Alkyl polyethylene glycol phosphate, potassium salt.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., potassium salt. 721.3900 Section 721.3900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.3900 Alkyl polyethylene glycol phosphate, potassium salt. (a) Chemical... as alkyl polyethylene glycol phosphate, potassium salt (P-90-481), is subject to reporting under this...

40 CFR 721.3900 - Alkyl polyethylene glycol phosphate, potassium salt.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., potassium salt. 721.3900 Section 721.3900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.3900 Alkyl polyethylene glycol phosphate, potassium salt. (a) Chemical... as alkyl polyethylene glycol phosphate, potassium salt (P-90-481), is subject to reporting under this...

40 CFR 721.3900 - Alkyl polyethylene glycol phosphate, potassium salt.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., potassium salt. 721.3900 Section 721.3900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.3900 Alkyl polyethylene glycol phosphate, potassium salt. (a) Chemical... as alkyl polyethylene glycol phosphate, potassium salt (P-90-481), is subject to reporting under this...

40 CFR 721.3900 - Alkyl polyethylene glycol phosphate, potassium salt.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., potassium salt. 721.3900 Section 721.3900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.3900 Alkyl polyethylene glycol phosphate, potassium salt. (a) Chemical... as alkyl polyethylene glycol phosphate, potassium salt (P-90-481), is subject to reporting under this...

Pyridine nucleotides in regulation of cell death and survival by redox and non-redox reactions.

PubMed

Novak Kujundžić, Renata; Žarković, Neven; Gall Trošelj, Koraljka

2014-01-01

Changes of the level and ratios of pyridine nucleotides determine metabolism- dependent cellular redox status and the activity of poly(ADP-ribose) polymerases (PARPs) and sirtuins, thereby influencing several processes closely related to cell survival and death. Pyridine nucleotides participate in numerous metabolic reactions whereby their net cellular level remains constant, but the ratios of NAD+/NADP+ and NADH/NADPH oscillate according to metabolic changes in response to diverse stress signals. In non-redox reactions, NAD+ is degraded and quickly, afterward, resynthesized in the NAD+ salvage pathway, unless overwhelming activation of PARP-1 consumes NAD+ to the point of no return, when the cell can no longer generate enough ATP to accommodate NAD+ resynthesis. The activity of PARP-1 is mandatory for the onset of cytoprotective autophagy on sublethal stress signals. It has become increasingly clear that redox status, largely influenced by the metabolism-dependent composition of the pyridine nucleotides pool, plays an important role in the synthesis of pro-apoptotic and anti-apoptotic sphingolipids. Awareness of the involvement of the prosurvival sphingolipid, sphingosine-1-phosphate, in transition from inflammation to malignant transformation has recently emerged. Here, the participation of pyridine nucleotides in redox and non-redox reactions, sphingolipid metabolism, and their role in cell fate decisions is reviewed.

Glutathione redox potential in the mitochondrial intermembrane space is linked to the cytosol and impacts the Mia40 redox state

PubMed Central

Kojer, Kerstin; Bien, Melanie; Gangel, Heike; Morgan, Bruce; Dick, Tobias P; Riemer, Jan

2012-01-01

Glutathione is an important mediator and regulator of cellular redox processes. Detailed knowledge of local glutathione redox potential (EGSH) dynamics is critical to understand the network of redox processes and their influence on cellular function. Using dynamic oxidant recovery assays together with EGSH-specific fluorescent reporters, we investigate the glutathione pools of the cytosol, mitochondrial matrix and intermembrane space (IMS). We demonstrate that the glutathione pools of IMS and cytosol are dynamically interconnected via porins. In contrast, no appreciable communication was observed between the glutathione pools of the IMS and matrix. By modulating redox pathways in the cytosol and IMS, we find that the cytosolic glutathione reductase system is the major determinant of EGSH in the IMS, thus explaining a steady-state EGSH in the IMS which is similar to the cytosol. Moreover, we show that the local EGSH contributes to the partially reduced redox state of the IMS oxidoreductase Mia40 in vivo. Taken together, we provide a comprehensive mechanistic picture of the IMS redox milieu and define the redox influences on Mia40 in living cells. PMID:22705944

Glycols modulate terminator stem stability and ligand-dependency of a glycine riboswitch.

PubMed

Hamachi, Kokoro; Hayashi, Hikari; Shimamura, Miyuki; Yamaji, Yuiha; Kaneko, Ai; Fujisawa, Aruma; Umehara, Takuya; Tamura, Koji

2013-08-01

The Bacillus subtilis glycine riboswitch comprises tandem glycine-binding aptamers and a putative terminator stem followed by the gcvT operon. Gene expression is regulated via the sensing of glycine. However, we found that the riboswitch behaves in a "glycine-independent" manner in the presence of polyethylene glycol (PEG) and ethylene glycol. The effect is related to the formation of a terminator stem within the expression platform under such conditions. The results revealed that increasing PEG stabilized the structure of the terminator stem. By contrast, the addition of ethylene glycol destabilized the terminator stem. PEG and ethylene glycol have opposite effects on transcription as well as on stable terminator stem formation. The glycine-independency of the riboswitch and the effects of such glycols might shed light on the evolution of riboswitches. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Characterization of redox conditions in groundwater contaminant plumes

NASA Astrophysics Data System (ADS)

Christensen, Thomas H.; Bjerg, Poul L.; Banwart, Steven A.; Jakobsen, Rasmus; Heron, Gorm; Albrechtsen, Hans-Jørgen

2000-10-01

Evaluation of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behaviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few cases have been reported. No standardised or generally accepted approach exists. Slow electrode kinetics and the common lack of internal equilibrium of redox processes in pollution plumes make, with a few exceptions, direct electrochemical measurement and rigorous interpretation of redox potentials dubious, if not erroneous. Several other approaches have been used in addressing redox conditions in pollution plumes: redox-sensitive compounds in groundwater samples, hydrogen concentrations in groundwater, concentrations of volatile fatty acids in groundwater, sediment characteristics and microbial tools, such as MPN counts, PLFA biomarkers and redox bioassays. This paper reviews the principles behind the different approaches, summarizes methods used and evaluates the approaches based on the experience from the reported applications.

The Expanding Landscape of the Thiol Redox Proteome*

PubMed Central

Yang, Jing; Carroll, Kate S.; Liebler, Daniel C.

2016-01-01

Cysteine occupies a unique place in protein chemistry. The nucleophilic thiol group allows cysteine to undergo a broad range of redox modifications beyond classical thiol-disulfide redox equilibria, including S-sulfenylation (-SOH), S-sulfinylation (-SO2H), S-sulfonylation (-SO3H), S-nitrosylation (-SNO), S-sulfhydration (-SSH), S-glutathionylation (-SSG), and others. Emerging evidence suggests that these post-translational modifications (PTM) are important in cellular redox regulation and protection against oxidative damage. Identification of protein targets of thiol redox modifications is crucial to understanding their roles in biology and disease. However, analysis of these highly labile and dynamic modifications poses challenges. Recent advances in the design of probes for thiol redox forms, together with innovative mass spectrometry based chemoproteomics methods make it possible to perform global, site-specific, and quantitative analyses of thiol redox modifications in complex proteomes. Here, we review chemical proteomic strategies used to expand the landscape of thiol redox modifications. PMID:26518762

All-soluble all-iron aqueous redox-flow battery

DOE PAGES

Gong, Ke; Xu, Fei; Grunewald, Jonathan B.; ...

2016-05-03

The rapid growth of intermittent renewable energy (e.g., wind and solar) demands low-cost and large-scale energy storage systems for smooth and reliable power output, where redox-flow batteries (RFBs) could find their niche. In this work, we introduce the first all-soluble all-iron RFB based on iron as the same redox-active element but with different coordination chemistries in alkaline aqueous system. The adoption of the same redox-active element largely alleviates the challenging problem of cross-contamination of metal ions in RFBs that use two redox-active elements. An all-soluble all-iron RFB is constructed by combining an iron–triethanolamine redox pair (i.e., [Fe(TEOA)OH] –/[Fe(TEOA)(OH)] 2–) andmore » an iron–cyanide redox pair (i.e., Fe(CN) 6 3–/Fe(CN) 6 4–), creating 1.34 V of formal cell voltage. Furthermore, good performance and stability have been demonstrated, after addressing some challenges, including the crossover of the ligand agent. As exemplified by the all-soluble all-iron flow battery, combining redox pairs of the same redox-active element with different coordination chemistries could extend the spectrum of RFBs.« less

Redox-sensitive micelles assembled from amphiphilic mPEG-PCL-SS-DTX conjugates for the delivery of docetaxel.

PubMed

Zhang, Huiyuan; Wang, Kaiming; Zhang, Pei; He, Wenxiu; Song, Aixin; Luan, Yuxia

2016-06-01

Docetaxel (DTX) can produce anti-tumor effects by inhibiting cell growth and inducing apoptosis. However, the poor solubility of DTX restricts its application and its clinical formulation has caused serious adverse reaction due to the use of Tween-80. In the present study, DTX was conjugated to an amphiphilic di-block polymer to solve these problems. Methoxy poly(ethylene glycol)-poly(ε-caprolactone) (mPEG-PCL) was selected as the polymer skeleton and a redox sensitive disulfide bond was used as the linker between DTX and mPEG-PCL. The synthesized mPEG-PCL-SS-DTX conjugates were characterized by (1)H-nuclear magnetic resonance ((1)H NMR) and Fourier transform infrared spectroscopy (FTIR). Interestingly, the mPEG-PCL-SS-DTX conjugates could self-assemble into micelles in aqueous solution. The critical micelle concentration (CMC) of mPEG-PCL-SS-DTX micelles was about 2.3mgL(-1) determined using pyrene molecule fluorescent probe method while the size of mPEG-PCL-SS-DTX micelles was determined to be ca. 17.6nm and 116.0nm with a bimodal distribution by dynamic light scattering (DLS). The in vitro release results indicated that the as-prepared micelles exhibited a sustained release profile with good redox sensitive properties. In particular, the hemolytic toxicity test indicated the as-prepared mPEG-PCL-SS-DTX micelles had negligible hemolytic activity, demonstrating their safety in drug delivery system. Cytotoxicity assay of the mPEG-PCL-SS-DTX micelles verified their highly enhanced cytotoxicity to MCF-7/A and A549 cells. These results thus demonstrated that the present redox-sensitive mPEG-PCL-SS-DTX micelle was an efficient and safe sustained drug delivery system in the biomedical area. Copyright © 2016 Elsevier B.V. All rights reserved.

21 CFR 573.800 - Polyethylene glycol (400) mono- and dioleate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.800 Polyethylene glycol (400) mono- and dioleate. (a) The food additive polyethylene glycol (400) mono- and dioleate meets the following specifications...

21 CFR 573.800 - Polyethylene glycol (400) mono- and dioleate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.800 Polyethylene glycol (400) mono- and dioleate. (a) The food additive polyethylene glycol (400) mono- and dioleate meets the following specifications...

21 CFR 573.800 - Polyethylene glycol (400) mono- and dioleate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.800 Polyethylene glycol (400) mono- and dioleate. (a) The food additive polyethylene glycol (400) mono- and dioleate meets the following specifications...

21 CFR 573.800 - Polyethylene glycol (400) mono- and dioleate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.800 Polyethylene glycol (400) mono- and dioleate. (a) The food additive polyethylene glycol (400) mono- and dioleate meets the following specifications...

21 CFR 573.800 - Polyethylene glycol (400) mono- and dioleate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.800 Polyethylene glycol (400) mono- and dioleate. (a) The food additive polyethylene glycol (400) mono- and dioleate meets the following specifications...

Redox Signaling in the Right Ventricle.

PubMed

Suzuki, Yuichiro J; Shults, Nataliia V

2017-01-01

Pulmonary hypertension is a devastating disease without cure. The major cause of death among patients with pulmonary hypertension is right heart failure; however, biology of the right heart is not well understood. This lack of knowledge interferes with developing effective therapeutic strategies to treat these patients. In this chapter, we summarize studies performed in our laboratory that investigated the role of redox signaling in the regulation of the right ventricle (RV), using rat models of experimental pulmonary hypertension and right heart failure. Specifically, this chapter covers the topics of (a) redox regulation of serotonin signaling in the RV, (b) the carbonylation-degradation pathway of signal transduction in RV hypertrophy and (c) oxidative modifications in the RV of the SU5416/ovalbumin model of pulmonary arterial hypertension. These studies revealed that redox regulation in the RV is complex and simply giving lots of antioxidants to patients will unlikely benefit them. Deeper understanding of specific and selective redox mechanisms should shed light on how we can develop therapeutic strategies by modulating redox reactions.

Identification of polypropylene glycols and polyethylene glycol carboxylates in flowback and produced water from hydraulic fracturing.

PubMed

Thurman, E Michael; Ferrer, Imma; Rosenblum, James; Linden, Karl; Ryan, Joseph N

2017-02-05

The purpose of the study was to separate and identify the unknown surfactants present in flowback and produced water from oil and gas wells in the Denver-Julesburg Basin (Niobrara Formation) in Weld County, Colorado, USA. Weld County has been drilled extensively during the last five years for oil and gas between 7000-8000 feet below land-surface. Polypropylene glycols (PPGs) and polyethylene glycols carboxylates (PEG-Cs) were found for the first time in these flowback and produced water samples. These ethoxylated surfactants may be used as friction reducers, clay stabilizers, and surfactants. Ultrahigh-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UHPLC/QTOF-MS) was used to separate and identify the different classes of PPGs, PEG-Cs, and their isomers. The Kendrick mass scale was applied along with mass spectrometry/mass spectrometry (MS-MS) with accurate mass for rapid and unequivocal identification. The PPGs and their isomers occur at the ppm concentration range and may be useful as "fingerprints" of hydraulic-fracturing. Comparing these detections to the compounds used in the fracturing process from FracFocus 3.0 (https://fracfocus.org), it appears that both PPGs and polyethylene glycols (PEGs) are commonly named as additives, but the PEG-Cs have not been reported. The PEG-Cs may be trace impurities or degradation products of PEGs. Copyright © 2016 Elsevier B.V. All rights reserved.

Redox homeostasis: The Golden Mean of healthy living.

PubMed

Ursini, Fulvio; Maiorino, Matilde; Forman, Henry Jay

2016-08-01

The notion that electrophiles serve as messengers in cell signaling is now widely accepted. Nonetheless, major issues restrain acceptance of redox homeostasis and redox signaling as components of maintenance of a normal physiological steady state. The first is that redox signaling requires sudden switching on of oxidant production and bypassing of antioxidant mechanisms rather than a continuous process that, like other signaling mechanisms, can be smoothly turned up or down. The second is the misperception that reactions in redox signaling involve "reactive oxygen species" rather than reaction of specific electrophiles with specific protein thiolates. The third is that hormesis provides protection against oxidants by increasing cellular defense or repair mechanisms rather than by specifically addressing the offset of redox homeostasis. Instead, we propose that both oxidant and antioxidant signaling are main features of redox homeostasis. As the redox shift is rapidly reversed by feedback reactions, homeostasis is maintained by continuous signaling for production and elimination of electrophiles and nucleophiles. Redox homeostasis, which is the maintenance of nucleophilic tone, accounts for a healthy physiological steady state. Electrophiles and nucleophiles are not intrinsically harmful or protective, and redox homeostasis is an essential feature of both the response to challenges and subsequent feedback. While the balance between oxidants and nucleophiles is preserved in redox homeostasis, oxidative stress provokes the establishment of a new radically altered redox steady state. The popular belief that scavenging free radicals by antioxidants has a beneficial effect is wishful thinking. We propose, instead, that continuous feedback preserves nucleophilic tone and that this is supported by redox active nutritional phytochemicals. These nonessential compounds, by activating Nrf2, mimic the effect of endogenously produced electrophiles (parahormesis). In summary

Unleashing the Power and Energy of LiFePO4-Based Redox Flow Lithium Battery with a Bifunctional Redox Mediator.

PubMed

Zhu, Yun Guang; Du, Yonghua; Jia, Chuankun; Zhou, Mingyue; Fan, Li; Wang, Xingzhu; Wang, Qing

2017-05-10

Redox flow batteries, despite great operation flexibility and scalability for large-scale energy storage, suffer from low energy density and relatively high cost as compared to the state-of-the-art Li-ion batteries. Here we report a redox flow lithium battery, which operates via the redox targeting reactions of LiFePO 4 with a bifunctional redox mediator, 2,3,5,6-tetramethyl-p-phenylenediamine, and presents superb energy density as the Li-ion battery and system flexibility as the redox flow battery. The battery has achieved a tank energy density as high as 1023 Wh/L, power density of 61 mW/cm 2 , and voltage efficiency of 91%. Operando X-ray absorption near-edge structure measurements were conducted to monitor the evolution of LiFePO 4 , which provides insightful information on the redox targeting process, critical to the device operation and optimization.

Oxidative protein folding: from thiol-disulfide exchange reactions to the redox poise of the endoplasmic reticulum.

PubMed

Hudson, Devin A; Gannon, Shawn A; Thorpe, Colin

2015-03-01

This review examines oxidative protein folding within the mammalian endoplasmic reticulum (ER) from an enzymological perspective. In protein disulfide isomerase-first (PDI-first) pathways of oxidative protein folding, PDI is the immediate oxidant of reduced client proteins and then addresses disulfide mispairings in a second isomerization phase. In PDI-second pathways the initial oxidation is PDI-independent. Evidence for the rapid reduction of PDI by reduced glutathione is presented in the context of PDI-first pathways. Strategies and challenges are discussed for determination of the concentrations of reduced and oxidized glutathione and of the ratios of PDI(red):PDI(ox). The preponderance of evidence suggests that the mammalian ER is more reducing than first envisaged. The average redox state of major PDI-family members is largely to almost totally reduced. These observations are consistent with model studies showing that oxidative protein folding proceeds most efficiently at a reducing redox poise consistent with a stoichiometric insertion of disulfides into client proteins. After a discussion of the use of natively encoded fluorescent probes to report the glutathione redox poise of the ER, this review concludes with an elaboration of a complementary strategy to discontinuously survey the redox state of as many redox-active disulfides as can be identified by ratiometric LC-MS-MS methods. Consortia of oxidoreductases that are in redox equilibrium can then be identified and compared to the glutathione redox poise of the ER to gain a more detailed understanding of the factors that influence oxidative protein folding within the secretory compartment. Copyright © 2014 Elsevier Inc. All rights reserved.

21 CFR 573.820 - Polyoxyethylene glycol (400) mono- and dioleates.

Code of Federal Regulations, 2011 CFR

2011-04-01

... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.820 Polyoxyethylene glycol (400) mono- and dioleates. The food additive polyoxyethylene glycol (400) mono- and dioleates may be safely used as an emulsifier...

21 CFR 573.820 - Polyoxyethylene glycol (400) mono- and dioleates.

Code of Federal Regulations, 2014 CFR

2014-04-01

... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.820 Polyoxyethylene glycol (400) mono- and dioleates. The food additive polyoxyethylene glycol (400) mono- and dioleates may be safely used as an emulsifier...

21 CFR 573.820 - Polyoxyethylene glycol (400) mono- and dioleates.

Code of Federal Regulations, 2013 CFR

2013-04-01

... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.820 Polyoxyethylene glycol (400) mono- and dioleates. The food additive polyoxyethylene glycol (400) mono- and dioleates may be safely used as an emulsifier...

21 CFR 573.820 - Polyoxyethylene glycol (400) mono- and dioleates.

Code of Federal Regulations, 2010 CFR

2010-04-01

... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.820 Polyoxyethylene glycol (400) mono- and dioleates. The food additive polyoxyethylene glycol (400) mono- and dioleates may be safely used as an emulsifier...

21 CFR 573.820 - Polyoxyethylene glycol (400) mono- and dioleates.

Code of Federal Regulations, 2012 CFR

2012-04-01

... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.820 Polyoxyethylene glycol (400) mono- and dioleates. The food additive polyoxyethylene glycol (400) mono- and dioleates may be safely used as an emulsifier...

Hydroxyapatite catalyzed aldol condensation: Synthesis, spectral linearity, antimicrobial and insect antifeedant activities of some 2,5-dimethyl-3-furyl chalcones

NASA Astrophysics Data System (ADS)

Subramanian, M.; Vanangamudi, G.; Thirunarayanan, G.

2013-06-01

A series of 2,5-dimethyl-3-furyl chalcones [2E-1-(2,5-dimethyl-3-furyl)-3-(substituted phenyl)-2-propen-1-ones] have been synthesized by Hydrotalcite catalyzed aldol condensation between 3-acetyl-2,5-dimethylfuron and substituted benzaldehydes. Yields of chalcones are more than 80%. These chalcones were characterized by their physical constants and spectral data. The group frequencies of infrared ν(cm-1) of CO s-cis and s-trans, CH in-plane and out of plane, CHdbnd CH out of plane, lbond2 Cdbnd Crbond2 out of plane modes, NMR chemical shifts δ(ppm) of Hα, Hβ, CO, Cα and Cβ of these chalcones were correlated with Hammett substituent constants, F and R parameters using single and multi-regression analyses. From the results of statistical analyses, the effects of substituents on the group frequencies are explained. Antibacterial, antifungal and insect antifeedant activities of these chalcones have been studied.

Severe propylene glycol toxicity secondary to use of anti-epileptics.

PubMed

Pillai, Unnikrishnan; Hothi, Jatinder C; Bhat, Zeenat Y

2014-01-01

Propylene glycol toxicity presenting as high anion gap metabolic acidosis and osmolar gap has been extensively reported in literature, and most of them are secondary to intravenous lorazepam infusion. However, propylene glycol is used as a solvent in a number of medications that are frequently utilized in critical care setting, and hence one should be aware that the toxicity is possible from a variety of medication. Phenobarbital and phenytoin are one of those, and we hereby report a novel case of propylene glycol toxicity secondary to phenobarbital and phenytoin infusion in a patient with refractory status epilepticus. Furthermore, our patient had end-stage renal disease, which we think could have been an important precipitating factor for the toxicity. Because most of the symptoms from propylene glycol toxicity can mimic sepsis-which is very common in critical care unit patients-this life threatening scenario could be easily missed. Regular monitoring of osmolar gap is an easily available intervention in the at risk patients.

The effects of certain glycols, substituted glycols and related organic solvents on the thermal stability of soluble collagen

PubMed Central

Hart, G. J.; Russell, A. E.; Cooper, D. R.

1971-01-01

The effects of a number of related diols, substituted diols and glycerol on the thermal stability of acid-soluble calf skin collagen were investigated. Thermal transition temperatures were determined by optical rotation measurement. Short-chain diols with terminal hydroxyl groups, i.e. ethylene glycol and propane-1,3-diol, stabilized the protein at all accessible concentrations. Stabilization was also observed with glycerol and diethylene glycol. Higher homologues in the diol series produced various effects, as did hydroxyl-group positional isomerism. Monoalkyl substitution of diols progressively lowered the denaturation temperature of collagen. Results are discussed in relation to possible mechanisms of perturbant action. PMID:5169191

21 CFR 172.850 - Lactylated fatty acid esters of glycerol and propylene glycol.

Code of Federal Regulations, 2014 CFR

2014-04-01

... propylene glycol. 172.850 Section 172.850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH... CONSUMPTION Multipurpose Additives § 172.850 Lactylated fatty acid esters of glycerol and propylene glycol. The food additive lactylated fatty acid esters of glycerol and propylene glycol may be safely used in...

40 CFR 180.1040 - Ethylene glycol; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Ethylene glycol; exemption from the... Exemptions From Tolerances § 180.1040 Ethylene glycol; exemption from the requirement of a tolerance. Ethylene glycol as a component of pesticide formulations is exempt from the requirement of a tolerance when...

Influence of Low Molecular Weight Fractions of Humic Substances on Their Reducing Capacities and Distribution of Redox Functional Groups.

NASA Astrophysics Data System (ADS)

Yang, Z.; Jiang, J.

2015-12-01

Humic substances (HS) are redox-active organic compounds and their reducing capacities depend on molecule structure and distribution of redox functional groups (RFG). During dialysis experiments, initial HS were separated into low molecular weight fractions (LMWF, molecular weight <3,500 Da or <14,000 Da) and retentate. LMWF accounts for only 2% in TOC contents of HS molecules, while their reducing capacities are up to 33 times greater than those of initial HA. However, great amount of reducing capacities of LMWF does not cause decreasing reducing capacities of retentate relative to those of initial HA. Total reducing capacities of whole dialysis device were calculated for initial HA, retentate and LMWF in native and reduced state, and result suggests that releasing of LMWF leads to production and explosion of RFG. LWMF have great fluorescence intensities for protein-like fluorophores and humic acids-like fluorophores (quinone-like functional groups), where quinonoid π-π* transition is responsible for the great reducing capacities of LMWF. The 3,500 Da molecules (0.25 nm diameter) of HS are capable of stimulating transformation of redox-active metals or potential pollutants trapped in soil micropores (< 2 nm diameter). A development of relationship between reducing capacity and Ex / Em position provides a possibility to predicate relative reducing capacities of HS in treated raw water sample.

High-Temperature Controlled Redox Crystallization Studies

NASA Technical Reports Server (NTRS)

Williams, R. J.

1985-01-01

The crystallization of silicates containing redox sensitive ions (e.g., Fe, Ti, Ce) must be performed under controlled and known redox conditions in order to obtain the maximum scientific benefit from experimental study. Furthermore, many compositions crystallize dense phases which settle during ground-based experiments. This settling influences the texture and chemical evolution of the crystallizing system. The purpose of this investigation is to develop a test system in which controlled redox experiments can be performed in the microgravity environment. The system will use solid ceramic oxygen electrolyte cells for control, measurements, and production of the required redox conditions. A preliminary design for a prototype is developed, the electrolyte and furnace tested, and a tentative protocol for experiment developed. The control parameter is to be established and a laboratory prototype built.

Broadband terahertz dynamics of propylene glycol monomer and oligomers

NASA Astrophysics Data System (ADS)

Koda, Shota; Mori, Tatsuya; Kojima, Seiji

2016-12-01

We investigated the broadband terahertz spectra (0.1-5.0 THz) of glass-forming liquids, propylene glycol (PG), its oligomers poly (propylene glycol)s (PPGs), and poly (propylene glycol) diglycidyl ether (PPG-de) using broadband terahertz time-domain spectroscopy and low-frequency Raman scattering. The numerical value of the dielectric loss at around 1.5 THz, which is the peak position of broad peaks in all samples, decreased as the molecular weight increased. Furthermore, the peak at around 1.5 THz is insensitive to the molecular weight. For PPGs, the side chain effect of the oligomer was observed in the terahertz region. Based on the experimental and calculation results for the PPGs and PPG-de, whose end groups are epoxy groups, the beginnings of the increases in the observed dielectric loss above 3.5 THz of the PPGs are assigned to the OH bending vibration. The higher value of the dielectric loss in the terahertz region for the PPG-de can be the tail of a broad peak located in the MHz region. The difference between the Raman susceptibility and dielectric loss reflects the difference in the observable molecular dynamics between the infrared and Raman spectroscopies.

Enzymatic remediated biodegradation of propylene glycol 1,2-dinitrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, M.; Geelhaar, L.; Speedie, M.K.

1995-12-31

Two bacterial species, Enterobacter agglomerans and Bacillus thuringiensis/cereus, which were selected from nitroglycerin (GTN) contaminated soil, have previously been shown to have denitrating ability on nitroglycerin. This abstract presents the investigation of the cell free extracts from both microorganisms for the degradation of another nitrate ester contaminant; propylene glycol 1,2-dinitrate (PGDN). This compound has been previously considered resistant to the biodegradation. In order to probe the pathway, the whole process was monitored by using [1-{sup 14}C]-PGDN as substrate and the intermediates were identified by HPLC and TLC chromatography. Long term biodegradation experiments have shown that the enzymes in the cytoplasmmore » fraction of Bacillus thuringiensis/cereus and the membrane fraction of Enterobacter agglomerans convert PGDN successively into propylene glycol 1-mononitrate (1-PGMN) and propylene glycol 2-mononitrate (2-PGMN), and finally, propylene glycol. The capacity to achieve sequential and complete degradation of PGDN implies that it follows a similar mechanism to that observed in the GTN degradation. Cofactor requirements for PGDN breakdown have been studied, it was found that no dissociable, dialyzable cofactors are required.« less

21 CFR 172.850 - Lactylated fatty acid esters of glycerol and propylene glycol.

Code of Federal Regulations, 2012 CFR

2012-04-01

... propylene glycol. 172.850 Section 172.850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH... esters of glycerol and propylene glycol. The food additive lactylated fatty acid esters of glycerol and propylene glycol may be safely used in food in accordance with the following prescribed conditions: (a) The...

21 CFR 172.850 - Lactylated fatty acid esters of glycerol and propylene glycol.

Code of Federal Regulations, 2013 CFR

2013-04-01

... propylene glycol. 172.850 Section 172.850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH... esters of glycerol and propylene glycol. The food additive lactylated fatty acid esters of glycerol and propylene glycol may be safely used in food in accordance with the following prescribed conditions: (a) The...

Energy storage device including a redox-enhanced electrolyte

DOEpatents

Stucky, Galen; Evanko, Brian; Parker, Nicholas; Vonlanthen, David; Auston, David; Boettcher, Shannon; Chun, Sang-Eun; Ji, Xiulei; Wang, Bao; Wang, Xingfeng; Chandrabose, Raghu Subash

2017-08-08

An electrical double layer capacitor (EDLC) energy storage device is provided that includes at least two electrodes and a redox-enhanced electrolyte including two redox couples such that there is a different one of the redox couples for each of the electrodes. When charged, the charge is stored in Faradaic reactions with the at least two redox couples in the electrolyte and in a double-layer capacitance of a porous carbon material that comprises at least one of the electrodes, and a self-discharge of the energy storage device is mitigated by at least one of electrostatic attraction, adsorption, physisorption, and chemisorption of a redox couple onto the porous carbon material.

Exercise-intensity dependent alterations in plasma redox status do not reflect skeletal muscle redox-sensitive protein signaling.

PubMed

Parker, Lewan; Trewin, Adam; Levinger, Itamar; Shaw, Christopher S; Stepto, Nigel K

2018-04-01

Redox homeostasis and redox-sensitive protein signaling play a role in exercise-induced adaptation. The effects of sprint-interval exercise (SIE), high-intensity interval exercise (HIIE) and continuous moderate-intensity exercise (CMIE), on post-exercise plasma redox status are unclear. Furthermore, whether post-exercise plasma redox status reflects skeletal muscle redox-sensitive protein signaling is unknown. In a randomized crossover design, eight healthy adults performed a cycling session of HIIE (5×4min at 75% W max ), SIE (4×30s Wingate's), and CMIE work-matched to HIIE (30min at 50% of W max ). Plasma hydrogen peroxide (H 2 O 2 ), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) activity, and catalase activity were measured immediately post, 1h, 2h and 3h post-exercise. Plasma redox status biomarkers were correlated with phosphorylation of skeletal muscle p38-MAPK, JNK, NF-κB, and IκBα protein content immediately and 3h post-exercise. Plasma catalase activity was greater with SIE (56.6±3.8Uml -1 ) compared to CMIE (42.7±3.2, p<0.01) and HIIE (49.0±5.5, p=0.07). Peak plasma H 2 O 2 was significantly (p<0.05) greater after SIE (4.6±0.6nmol/ml) and HIIE (4.1±0.4) compared to CMIE (3.3±0.5). Post-exercise plasma TBARS and SOD activity significantly (p<0.05) decreased irrespective of exercise protocol. A significant positive correlation was detected between plasma catalase activity and skeletal muscle p38-MAPK phosphorylation 3h post-exercise (r=0.40, p=0.04). No other correlations were detected (all p>0.05). Low-volume SIE elicited greater post-exercise plasma catalase activity compared to HIIE and CMIE, and greater H 2 O 2 compared to CMIE. Plasma redox status did not, however, adequately reflect skeletal muscle redox-sensitive protein signaling. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Propylene glycol monomethyl ether (PGME)

Integrated Risk Information System (IRIS)

Propylene glycol monomethyl ether ( PGME ) ; CASRN 107 - 98 - 2 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 Assess

Bimetallic ruthenium complexes bridged by divinylphenylene bearing oligo(ethylene glycol)methylether: synthesis, (spectro)electrochemistry and the lithium cation effect.

PubMed

Tian, Li Yan; Liu, Yuan Mei; Tian, Guang-Xuan; Wu, Xiang Hua; Li, Zhen; Kou, Jun-Feng; Ou, Ya-Ping; Liu, Sheng Hua; Fu, Wen-Fu

2014-03-14

A series of 1,4-disubstituted ruthenium-vinyl complexes, (E,E)-[{(PMe3)3(CO)ClRu}2(μ-HC=CH-Ar-CH=CH)], in which the 1,4-diethenylphenylene bridge bears two oligo(ethylene glycol)methyl ether side chains at different positions (2,5- and 2,3-positions), were prepared. The respective products were characterized by elemental analyses and NMR spectroscopy. The structures of complexes 1b and 1e were established by X-ray crystallography. The electronic properties of the complexes were investigated by cyclic voltammetry, and IR and UV-vis/NIR spectroscopies. Electrochemical studies showed that the 2,5-substituents better stabilized the mixed-valence states; the electrochemical behavior was greatly affected by lithium cations, especially complex 1g with 2,3-substituents, which was further supported by IR and UV-vis/NIR spectra changes. Spectroelectrochemical studies showed that the redox chemistry was dominated by the non-innocent character of the bridging fragment.

Biogeochemical redox processes and their impact on contaminant dynamics

USGS Publications Warehouse

Borch, Thomas; Kretzschmar, Ruben; Kappler, Andreas; Van Cappellen, Philippe; Ginder-Vogel, Matthew; Campbell, Kate M.

2010-01-01

Life and element cycling on Earth is directly related to electron transfer (or redox) reactions. An understanding of biogeochemical redox processes is crucial for predicting and protecting environmental health and can provide new opportunities for engineered remediation strategies. Energy can be released and stored by means of redox reactions via the oxidation of labile organic carbon or inorganic compounds (electron donors) by microorganisms coupled to the reduction of electron acceptors including humic substances, iron-bearing minerals, transition metals, metalloids, and actinides. Environmental redox processes play key roles in the formation and dissolution of mineral phases. Redox cycling of naturally occurring trace elements and their host minerals often controls the release or sequestration of inorganic contaminants. Redox processes control the chemical speciation, bioavailability, toxicity, and mobility of many major and trace elements including Fe, Mn, C, P, N, S, Cr, Cu, Co, As, Sb, Se, Hg, Tc, and U. Redox-active humic substances and mineral surfaces can catalyze the redox transformation and degradation of organic contaminants. In this review article, we highlight recent advances in our understanding of biogeochemical redox processes and their impact on contaminant fate and transport, including future research needs.

Redox properties of structural Fe in clay minerals: 3. Relationships between smectite redox and structural properties.

PubMed

Gorski, Christopher A; Klüpfel, Laura E; Voegelin, Andreas; Sander, Michael; Hofstetter, Thomas B

2013-01-01

Structural Fe in clay minerals is an important redox-active species in many pristine and contaminated environments as well as in engineered systems. Understanding the extent and kinetics of redox reactions involving Fe-bearing clay minerals has been challenging due to the inability to relate structural Fe(2+)/Fe(total) fractions to fundamental redox properties, such as reduction potentials (EH). Here, we overcame this challenge by using mediated electrochemical reduction (MER) and oxidation (MEO) to characterize the fraction of redox-active structural Fe (Fe(2+)/Fe(total)) in smectites over a wide range of applied EH-values (-0.6 V to +0.6 V). We examined Fe(2+)/Fe(total )- EH relationships of four natural Fe-bearing smectites (SWy-2, SWa-1, NAu-1, NAu-2) in their native, reduced, and reoxidized states and compared our measurements with spectroscopic observations and a suite of mineralogical properties. All smectites exhibited unique Fe(2+)/Fe(total) - EH relationships, were redox active over wide EH ranges, and underwent irreversible electron transfer induced structural changes that were observable with X-ray absorption spectroscopy. Variations among the smectite Fe(2+)/Fe(total) - EH relationships correlated well with both bulk and molecular-scale properties, including Fe(total) content, layer charge, and quadrupole splitting values, suggesting that multiple structural parameters determined the redox properties of smectites. The Fe(2+)/Fe(total) - EH relationships developed for these four commonly studied clay minerals may be applied to future studies interested in relating the extent of structural Fe reduction or oxidation to EH-values.

Sequential episodes of ethylene glycol poisoning in the same person.

PubMed

Sugunaraj, Jaya Prakash; Thakur, Lokendra Kumar; Jha, Kunal Kishor; Bucaloiu, Ion Dan

2017-05-27

Ethylene glycol is a common alcohol found in many household products such as household hard surface cleaner, paints, varnish, auto glass cleaner and antifreeze. While extremely toxic and often fatal on ingestion, few cases with early presentation by the patient have resulted in death; thus, rapid diagnosis is paramount to effectively treating ethylene glycol poisoning. In this study, we compare two sequential cases of ethylene glycol poisoning in a single individual, which resulted in strikingly different outcomes. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Phenolic Polymer Solvation in Water and Ethylene Glycol, II: Ab Initio Computations.

PubMed

Bauschlicher, Charles W; Bucholz, Eric W; Haskins, Justin B; Monk, Joshua D; Lawson, John W

2017-04-06

Ab initio techniques are used to study the interaction of ethylene glycol and water with a phenolic polymer. The water bonds more strongly with the phenolic OH than with the ring. The phenolic OH groups can form hydrogen bonds between themselves. For more than one water molecule, there is a competition between water-water and water-phenolic interactions. Ethylene glycol shows the same effects as those of water, but the potential energy surface is further complicated by CH 2 -phenolic interactions, different conformers of ethylene glycol, and two OH groups on each molecule. Thus, the ethylene glycol-phenolic potential is more complicated than the water-phenolic potential. The results of the ab initio calculations are compared to those obtained using a force field. These calibration studies show that the water system is easier to describe than the ethylene glycol system. The calibration studies confirm the reliability of force fields used in our companion molecular dynamics study of a phenolic polymer in water and ethylene solutions.

Facile fabrication of redox-responsive thiol-containing drug delivery system via RAFT polymerization.

PubMed

Zhuang, Yuanyuan; Su, Yue; Peng, Yu; Wang, Dali; Deng, Hongping; Xi, Xiaodong; Zhu, Xinyuan; Lu, Yunfeng

2014-04-14

A novel kind of redox-responsive polymeric drug delivery system has been designed and prepared successfully through the coupling of the multithiol branched polymers and thiol-containing drugs. The branched poly((S-(4-vinyl) benzyl S'-propyltrithiocarbonate)-co-(poly(ethylene glycol) methacrylate)) (poly(VBPT-co-PEGMA)) was synthesized by one-pot reaction via reversible addition-fragmentation chain transfer (RAFT) copolymerization. Subsequently, the hydrophobic thiol-containing anticancer drug 6-mercaptopurine (MP) was conjugated to poly(VBPT-co-PEGMA) by thiol-disulfide exchange reaction, resulting in the formation of poly(VBPT-co-PEGMA)-S-S-MP conjugate. Due to its amphiphilicity, poly(VBPT-co-PEGMA)-S-S-MP conjugate self-assembled into amphiphilic micelles in aqueous solution. Under a reductive environment, the disassembly of polymeric micelles resulted in the MP release. Flow cytometry and confocal laser scanning microscopy (CLSM) measurements demonstrated that the poly(VBPT-co-PEGMA)-S-S-MP micelles could be taken up by Raji cells (a Burkitt lymphoma cell line). The viability of the Raji cells incubated with the glutathione (GSH) mediated poly(VBPT-co-PEGMA)-S-S-MP micelles was investigated by Cell Counting Kit-8 (CCK-8) assay. The experimental results showed that the viability of the glutathione monoester (GSH-OEt) pretreated cells was lower than that without pretreatment, while the viability of the buthionine sulfoximine (BSO) pretreated cells was higher than that without pretreatment. The poly(VBPT-co-PEGMA)-S-S-MP micelles could induce the apoptosis of Raji cells, and the apoptosis behavior was dose-dependent. This redox-responsive polymer-drug conjugate provides a promising platform for the delivery of thiol-containing biological molecules.

Organelle Redox of CF and CFTR-Corrected Airway Epithelia

PubMed Central

Schwarzer, Christian; Illek, Beate; Suh, Jung H.; Remington, S. James; Fischer, Horst; Machen, Terry E.

2014-01-01

In cystic fibrosis reduced CFTR function may alter redox properties of airway epithelial cells. Redox-sensitive GFP (roGFP1) and imaging microscopy were used to measure redox potentials of cytosol, ER, mitochondria and cell surface of cystic fibrosis nasal epithelial cells and CFTR-corrected cells. We also measured glutathione and cysteine thiol redox states in cell lysates and apical fluids to provide coverage over a range of redox potentials and environments that might be affected by CFTR. As measured with roGFP1, redox potentials at the cell surface (~ -207 ±8 mV) and in the ER (~ -217 ±1 mV) and rates of regulation of the apical fluid and ER lumen following DTT treatment were similar for CF and CFTR-corrected cells. CF and CFTR-corrected cells had similar redox potentials in mitochondria (-344 ±9 mV) and cytosol (-322 ±7 mV). Oxidation of carboxy-dichlorodihydrofluoresceindiacetate and of apical Amplex Red occurred at equal rates in CF and CFTR-corrected cells. Glutathione and cysteine redox couples in cell lysates and apical fluid were equal in CF and CFTR-corrected cells. These quantitative estimates of organelle redox potentials combined with apical and cell measurements using small molecule couples confirmed there were no differences in redox properties of CF and CFTR-corrected cells. PMID:17603939

NASA Redox Storage System Development Project

NASA Technical Reports Server (NTRS)

Hagedorn, N. H.

1984-01-01

The Redox Storage System Technology Project was jointly supported by the U.S. Department of Energy and NASA. The objectives of the project were to develop the Redox flow battery concept and to probe its technical and economic viability. The iron and chromium redox couples were selected as the reactants. Membranes and electrodes were developed for the original mode of operating at 25 C with the reactants separated by an ion-exchange membrane. Analytical capabilities and system-level operating concepts were developed and verified in a 1-kW, 13-kWh preprototype system. A subsequent change was made in operating mode, going to 65 C and using mixed reactants. New membranes and a new electrode catalyst were developed, resulting in single cell operation as high as 80 mA/sq cm with energy efficiencies greater than 80 percent. Studies indicate a likely system cost of about $75/kWh. Standard Oil of Ohio (Sohio) has undertaken further development of the Redox system. An exclusive patent license was obtained from NASA by Sohio. Transfer of Redox technology to Sohio is supported by the NASA Technology Utilization Office.

Oligoethylene Glycol-substituted Aza-BODIPY Dyes As Red Emitting ER-Probes

PubMed Central

Kamkaew, Anyanee; Thavornpradit, Sopida; Puangsamlee, Thamon; Xin, Dongyue; Wanichacheva, Nantanit; Burgess, Kevin

2015-01-01

This study features aza-BODIPY (BF2-chelated azadipyrromethene) dyes with two aromatic substituents linked by oligoethylene glycol fragments to increase hydrophilicity of aza-BODIPY for applications in intracellular imaging. To prepare these, two chalcones were attached α,ω onto oligoethylene glycol fragments, then reacted with nitromethane anion. Conjugate addition products from this reaction were then subjected to typical conditions for synthesis of aza-BODIPY dyes (NH4OAc, nBuOH, 120 °C); formation of boracycles in this reaction was concomitant with creation of macrocycles containing the oligoethylene glycol fragments. Similar dyes with acyclic oligoelythene glycol substituents in the same position were used to compare the efficiencies of the intra- and inter-molecular aza-BODIPY forming reactions, and the characteristics of the products. All the fluors with oligoethylene glycol fragments, ie cyclic or acyclic, localized in the endoplasmic reticulum of a fibroblast cell line (WEHI-13VAR), the human pancreatic cancer cell line (PANC-1, rough ER predominates) and human liver cancer cell line (HepG2, smooth ER prevalent). These fluors are potentially useful for near IR (λmax emis at 730 nm) ER staining probes. PMID:26138325

Effect of Hygrophila spinosa in ethylene glycol induced nephrolithiasis in rats.

PubMed

Ingale, Kundan G; Thakurdesai, Prasad A; Vyawahare, Neeraj S

2012-01-01

Hygrophila spinosa (Acanthaceae) is traditionally used to treat urinary calculi. The present study aimed to evaluate the antiurolithiatic activity of methanolic extract of Hygrophila spinosa (Acanthaceae) in ethylene glycol induced nephrolithiasic rats. Methanolic extract of Hygrophila spinosa (HSME) (250 and 500 mg/ kg body weight) was administered orally to male Wistar albino rats. Ethylene glycol (EG) was used to induce nephrolithiasis. The parameters studied included water intake, urinary volume, urinary pH, urinary and kidney oxalate and calcium, urinary magnesium and serum uric acid. Ethylene glycol feeding resulted in hyperoxaluria as well as increased renal excretion of calcium and serum uric acid along with decreased excretion of urinary magnesium. Treatment with HSME significantly reduced the elevated urinary oxalate, urinary calcium and serum uric acid with increase in reduced urinary magnesium. Ethylene glycol feeding also resulted in increased levels of calcium and oxalate in kidney which was decreased after the treatment with HSME. The increased deposition of stone forming constituents in the kidneys of ethylene glycol treated rats was significantly lowered by treatment with HSME. The results indicate that the aerial parts of Hygrophila spinosa are endowed with antiurolithiatic activity, thereby justifying its traditional claim.

Redox polymer electrodes for advanced batteries

DOEpatents

Gregg, Brian A.; Taylor, A. Michael

1998-01-01

Advanced batteries having a long cycle lifetime are provided. More specifically, the present invention relates to electrodes made from redox polymer films and batteries in which either the positive electrode, the negative electrode, or both, comprise redox polymers. Suitable redox polymers for this purpose include pyridyl or polypyridyl complexes of transition metals like iron, ruthenium, osmium, chromium, tungsten and nickel; porphyrins (either free base or metallo derivatives); phthalocyanines (either free base or metallo derivatives); metal complexes of cyclams, such as tetraazacyclotetradecane; metal complexes of crown ethers and metallocenes such as ferrocene, cobaltocene and ruthenocene.

Redox Regulation of Neuronal Voltage-Gated Calcium Channels

PubMed Central

Jevtovic-Todorovic, Vesna

2014-01-01

Abstract Significance: Voltage-gated calcium channels are ubiquitously expressed in neurons and are key regulators of cellular excitability and synaptic transmitter release. There is accumulating evidence that multiple subtypes of voltage-gated calcium channels may be regulated by oxidation and reduction. However, the redox mechanisms involved in the regulation of channel function are not well understood. Recent Advances: Several studies have established that both T-type and high-voltage-activated subtypes of voltage-gated calcium channel can be redox-regulated. This article reviews different mechanisms that can be involved in redox regulation of calcium channel function and their implication in neuronal function, particularly in pain pathways and thalamic oscillation. Critical Issues: A current critical issue in the field is to decipher precise mechanisms of calcium channel modulation via redox reactions. In this review we discuss covalent post-translational modification via oxidation of cysteine molecules and chelation of trace metals, and reactions involving nitric oxide-related molecules and free radicals. Improved understanding of the roles of redox-based reactions in regulation of voltage-gated calcium channels may lead to improved understanding of novel redox mechanisms in physiological and pathological processes. Future Directions: Identification of redox mechanisms and sites on voltage-gated calcium channel may allow development of novel and specific ion channel therapies for unmet medical needs. Thus, it may be possible to regulate the redox state of these channels in treatment of pathological process such as epilepsy and neuropathic pain. Antioxid. Redox Signal. 21, 880–891. PMID:24161125

Microfluidic Valves Made From Polymerized Polyethylene Glycol Diacrylate

PubMed Central

Rogers, Chad I.; Oxborrow, Joseph B.; Anderson, Ryan R.; Tsai, Long-Fang; Nordin, Gregory P.; Woolley, Adam T.

2013-01-01

Pneumatically actuated, non-elastomeric membrane valves fabricated from polymerized polyethylene glycol diacrylate (poly-PEGDA) have been characterized for temporal response, valve closure, and long-term durability. A ~100 ms valve opening time and a ~20 ms closure time offer valve operation as fast as 8 Hz with potential for further improvement. Comparison of circular and rectangular valve geometries indicates that the surface area for membrane interaction in the valve region is important for valve performance. After initial fabrication, the fluid pressure required to open a closed circular valve is ~50 kPa higher than the control pressure holding the valve closed. However, after ~1000 actuations to reconfigure polymer chains and increase elasticity in the membrane, the fluid pressure required to open a valve becomes the same as the control pressure holding the valve closed. After these initial conditioning actuations, poly-PEGDA valves show considerable robustness with no change in effective operation after 115,000 actuations. Such valves constructed from non-adsorptive poly-PEGDA could also find use as pumps, for application in small volume assays interfaced with biosensors or impedance detection, for example. PMID:24357897

21 CFR 184.1666 - Propylene glycol.

Code of Federal Regulations, 2014 CFR

2014-04-01

... chlorinated water to form the chlorohydrin which is converted to the glycol by treatment with sodium carbonate solution. It is also prepared by heating glyercol with sodium hydroxide. (b) The ingredient meets the...

The Verification of a Method for Detecting and Quantifying Diethylene Glycol, Triethylene Glycol, Tetraethylene Glycol, 2-Butoxyethanol and 2-Methoxyethanolin in Ground and Surface Waters

EPA Science Inventory

This verification study was a special project designed to determine the efficacy of a draft standard operating procedure (SOP) developed by US EPA Region 3 for the determination of selected glycols in drinking waters that may have been impacted by active unconventional oil and ga...

Synthesis and characterization of poly(lactic acid-co-glycolic acid) complex microspheres as drug carriers.

PubMed

Wang, Fang; Liu, Xiuxiu; Yuan, Jian; Yang, Siqian; Li, Yueqin; Gao, Qinwei

2016-10-01

Poly(lactic-co-glycolic) acid (PLGA) is synthesized via melt polycondensation directly from lactic acid and glycolic acid with a feed molar ratio of 75/25. Bovine serum albumin, which is used as model protein, is entrapped into the poly(lactic-co-glycolic acid) microspheres with particle size of 260.9 ± 20.0 nm by the double emulsification method. Then it is the first report of producing more carboxyl groups by poly(lactic-co-glycolic acid) surface hydrolysis. The purpose is developing poly(lactic-co-glycolic acid) microspheres surface, which is modified with chitosan by chemical reaction between carboxyl groups and amine groups. The particle size and the positive zeta potential of the poly(lactic-co-glycolic acid)/chitosan microspheres are 388.2 ± 35.6 nm and 10.4 ± 2.9 mV, respectively. The drug loading ratio and encapsulation efficacy of poly(lactic-co-glycolic acid)/chitosan microspheres are 36.3% and 57.5%, which are higher than PLGA microspheres. Furthermore, the drug burst release of poly(lactic-co-glycolic acid)/chitosan microspheres at 10 h is decreased to 21.72% while the corresponding value of the poly(lactic-co-glycolic acid) microsphere is 64.56%. These results reveal that surface hydrolysis modification of poly(lactic-co-glycolic acid) is an efficient method to improve the negative potential and chemical reaction properties of the polymer. And furthermore, this study shows that chitosan-modified poly(lactic-co-glycolic acid) microspheres is a promising system for the controlled release of pharmaceutical proteins. © The Author(s) 2016.

Photodynamic therapy of tumors with pyropheophorbide-a-loaded polyethylene glycol-poly(lactic-co-glycolic acid) nanoparticles.

PubMed

Liu, Hui; Zhao, Mei; Wang, Jin; Pang, Mingpei; Wu, Zhenzhou; Zhao, Liqing; Yin, Zhinan; Hong, Zhangyong

Photodynamic therapy (PDT) has many advantages in treating cancers, but the lack of ideal photosensitizers continues to be a major limitation restricting the clinical utility of PDT. This study aimed to overcome this obstacle by generating pyropheophorbide- a -loaded polyethylene glycol-poly(lactic- co -glycolic acid) nanoparticles (NPs) for efficient tumor-targeted PDT. The fabricated NPs were efficiently internalized in the mitochondrion by cancer cells, and they efficiently killed cancer cells in a dose-dependent manner when activated with light. Systemically delivered NPs were highly enriched in tumor sites, and completely ablated the tumors in a xenograft KB tumor mouse model when illuminated with 680 nm light (156 mW/cm 2 , 10 minutes). The results suggested that this tumor-specific NP-delivery system for pyropheophorbide- a has the potential to be used in tumor-targeted PDT.

Method for characterization of the redox condition of cementitious materials

DOEpatents

Almond, Philip M.; Langton, Christine A.; Stefanko, David B.

2015-12-22

Disclosed are methods for determining the redox condition of cementitious materials. The methods are leaching methods that utilize an in situ redox indicator that is present in the cementitious materials as formed. The in situ redox indicator leaches from cementitious material and, when the leaching process is carried out under anaerobic conditions can be utilized to determine the redox condition of the material. The in situ redox indicator can exhibit distinct characteristics in the leachate depending upon the redox condition of the indicator.

The influence of water mixtures on the dermal absorption of glycol ethers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Traynor, Matthew J.; Wilkinson, Simon C.; Williams, Faith M.

2007-01-15

Glycol ethers are solvents widely used alone and as mixtures in industrial and household products. Some glycol ethers have been shown to have a range of toxic effects in humans following absorption and metabolism to their aldehyde and acid metabolites. This study assessed the influence of water mixtures on the dermal absorption of butoxyethanol and ethoxyethanol in vitro through human skin. Butoxyethanol penetrated human skin up to sixfold more rapidly from aqueous solution (50%, 450 mg/ml) than from the neat solvent. Similarly penetration of ethoxyethanol was increased threefold in the presence of water (50%, 697 mg/ml). There was a correspondingmore » increase in apparent permeability coefficient as the glycol ether concentration in water decreased. The maximum penetration rate of water also increased in the presence of both glycol ethers. Absorption through a synthetic membrane obeyed Fick's Law and absorption through rat skin showed a similar profile to human skin but with a lesser effect. The mechanisms for this phenomenon involves disruption of the stratum corneum lipid bilayer by desiccation by neat glycol ether micelles, hydration with water mixtures and the physicochemical properties of the glycol ether-water mixtures. Full elucidation of the profile of absorption of glycol ethers from mixtures is required for risk assessment of dermal exposure. This work supports the view that risk assessments for dermal contact scenarios should ideally be based on absorption data obtained for the relevant formulation or mixture and exposure scenario and that absorption derived from permeability coefficients may be inappropriate for water-miscible solvents.« less

21 CFR 184.1666 - Propylene glycol.

Code of Federal Regulations, 2013 CFR

2013-04-01

... glycol by treatment with sodium carbonate solution. It is also prepared by heating glyercol with sodium hydroxide. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), p. 255...

21 CFR 184.1666 - Propylene glycol.

Code of Federal Regulations, 2012 CFR

2012-04-01

... glycol by treatment with sodium carbonate solution. It is also prepared by heating glyercol with sodium hydroxide. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), p. 255...

Monitoring thioredoxin redox with a genetically encoded red fluorescent biosensor.

PubMed

Fan, Yichong; Makar, Merna; Wang, Michael X; Ai, Hui-Wang

2017-09-01

Thioredoxin (Trx) is one of the two major thiol antioxidants, playing essential roles in redox homeostasis and signaling. Despite its importance, there is a lack of methods for monitoring Trx redox dynamics in live cells, hindering a better understanding of physiological and pathological roles of the Trx redox system. In this work, we developed the first genetically encoded fluorescent biosensor for Trx redox by engineering a redox relay between the active-site cysteines of human Trx1 and rxRFP1, a redox-sensitive red fluorescent protein. We used the resultant biosensor-TrxRFP1-to selectively monitor perturbations of Trx redox in various mammalian cell lines. We subcellularly localized TrxRFP1 to image compartmentalized Trx redox changes. We further combined TrxRFP1 with a green fluorescent Grx1-roGFP2 biosensor to simultaneously monitor Trx and glutathione redox dynamics in live cells in response to chemical and physiologically relevant stimuli.

Redox signaling in cardiovascular health and disease

PubMed Central

Madamanchi, Nageswara R.; Runge, Marschall S.

2013-01-01

Spatiotemporal regulation of the activity of a vast array of intracellular proteins and signaling pathways by reactive oxygen species (ROS) governs normal cardiovascular function. However, data from experimental and animal studies strongly support that dysregulated redox signaling, resulting from hyper-activation of various cellular oxidases or mitochondrial dysfunction, is integral to the pathogenesis and progression of cardiovascular disease (CVD). In this review, we address how redox signaling modulates the protein function, the various sources of increased oxidative stress in CVD, and the labyrinth of redox-sensitive molecular mechanisms involved in the development of atherosclerosis, hypertension, cardiac hypertrophy and heart failure, and ischemia–reperfusion injury. Advances in redox biology and pharmacology for inhibiting ROS production in specific cell types and subcellular organelles combined with the development of nanotechnology-based new in vivo imaging systems and targeted drug delivery mechanisms may enable fine-tuning of redox signaling for the treatment and prevention of CVD. PMID:23583330

Nanostructured Electrocatalysts for All-Vanadium Redox Flow Batteries.

PubMed

Park, Minjoon; Ryu, Jaechan; Cho, Jaephil

2015-10-01

Vanadium redox reactions have been considered as a key factor affecting the energy efficiency of the all-vanadium redox flow batteries (VRFBs). This redox reaction determines the reaction kinetics of whole cells. However, poor kinetic reversibility and catalytic activity towards the V(2+)/V(3+) and VO(2+)/VO2(+) redox couples on the commonly used carbon substrate limit broader applications of VRFBs. Consequently, modified carbon substrates have been extensively investigated to improve vanadium redox reactions. In this Focus Review, recent progress on metal- and carbon-based nanomaterials as an electrocatalyst for VRFBs is discussed in detail, without the intention to provide a comprehensive review on the whole components of the system. Instead, the focus is mainly placed on the redox chemistry of vanadium ions at a surface of various metals, different dimensional carbons, nitrogen-doped carbon nanostructures, and metal-carbon composites. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Redox states of Desulfovibrio vulgaris DsrC, a key protein in dissimilatory sulfite reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Venceslau, Sofia S.; Cort, John R.; Baker, Erin S.

2013-11-29

Highlights: •DsrC is known to interact with the dissimilatory sulfite reductase enzyme (DsrAB). •We show that, however, most cellular DsrC is not associated with DsrAB. •A gel-shift assay was developed that allows monitoring of the DsrC redox state. •The DsrC intramolecularly oxidized state could only be produced by arginine treatment. -- Abstract: Dissimilatory reduction of sulfite is carried out by the siroheme enzyme DsrAB, with the involvement of the protein DsrC, which has two conserved redox-active cysteines. DsrC was initially believed to be a third subunit of DsrAB. Here, we report a study of the distribution of DsrC in cellmore » extracts to show that, in the model sulfate reducer Desulfovibrio vulgaris, the majority of DsrC is not associated with DsrAB and is thus free to interact with other proteins. In addition, we developed a cysteine-labelling gel-shift assay to monitor the DsrC redox state and behaviour, and procedures to produce the different redox forms. The oxidized state of DsrC with an intramolecular disulfide bond, which is proposed to be a key metabolic intermediate, could be successfully produced for the first time by treatment with arginine.« less

Redox sensing: Orthogonal control in cell cycle and apoptosis signaling

PubMed Central

Jones, Dean P.

2010-01-01

Living systems have three major types of cell signaling systems that are dependent upon high-energy chemicals, redox environment and transmembranal ion gating mechanisms. Development of integrated systems biology descriptions of cell signaling require conceptual models incorporating all three. Recent advances in redox biology show that thiol/disulfide redox systems are regulated under dynamic, non-equilibrium conditions, progressively oxidized with the life cycle of cells and distinct in terms of redox potentials among subcellular compartments. The present article uses these observations as a basis to distinguish “redox-sensing” mechanisms, which are more global biologic redox control mechanisms, from “redox signaling”, which involves conveyance of discrete activating or inactivating signals. Both redox sensing and redox signaling use sulfur switches, especially cysteine (Cys) residues in proteins which are sensitive to reversible oxidation, nitrosylation, glutathionylation, acylation, sulfhydration or metal binding. Unlike specific signaling mechanisms, the redox-sensing mechanisms provide means to globally affect the rates and activities of the high-energy, ion gating and redox-signaling systems by controlling sensitivity, distribution, macromolecular interactions and mobility of signaling proteins. Effects mediated through Cys residues not directly involved in signaling means redox-sensing control can be orthogonal to the signaling mechanisms. This provides a capability to integrate signals according to cell cycle and physiologic state without fundamentally altering the signaling mechanisms. Recent findings that thiol/disulfide pools in humans are oxidized with age, environmental exposures and disease risk suggest that redox-sensing thiols could provide a central mechanistic link in disease development and progression. PMID:20964735

A retention index system for comprehensive two-dimensional gas chromatography using polyethylene glycols.

PubMed

Veenaas, Cathrin; Haglund, Peter

2018-02-09

The characterization and identification of compounds in complex real-world samples is quite difficult and new concepts and workflows are highly desirable. Retention indices (RIs) are widely used in gas chromatography (GC) to support the identification of unknown compounds. Several attempts have been made to introduce a similar concept for the second dimension in comprehensive two-dimensional (2D) GC (GC × GC) but, an easily applicable and robust system remains elusive. In the present study, a new RI system for GC × GC was developed. Polyethylene glycols (PEGs) were used in combination with a simple linear regression, with n-alkanes as reference points for virtually unretained compounds and PEG homologs as reference compounds for second-dimension RIs (PEG- 2 I). The n-alkanes were assigned a PEG- 2 I of zero and the distance between consecutive PEG homologs from PEG-2 (diethylene glycol) and higher were assigned a PEG- 2 I value of 10. We used ethylene glycol and PEG-2 through PEG-10 as reference compounds, thereby covering a PEG- 2 I range from 20.0 for ethylene glycol, over 50.0 for diethylene glycol (PEG-2) to 130.0 for decaethylene glycol (PEG-10); additional PEGs can be added to cover a wider polarity range. The PEG- 2 I system was initially evaluated using a 30 m × 0.25 mm non-polar (5% phenyl, 0.25 μm film thickness) first-dimension column and a 1.6 m × 0.18 mm polar (50% phenyl, 0.18 μm film thickness) second-dimension column. This system was validated for use with non-polar first-dimension columns and a semi-polar (50% phenyl) second-dimension column, and exhibited robustness to changes in the carrier gas flow velocity, oven temperature ramping rate, and secondary oven temperature offset. An average relative standard deviation of 2.7%, equal to a 95% confidence interval of 1.27 PEG- 2 I units, was obtained for the PEG- 2 I values of 72 environmental pollutants. Additionally, the system was found to be applicable over a wide

Cytochemical Localization of Glycolate Dehydrogenase in Mitochondria of Chlamydomonas1

PubMed Central

Beezley, Belinda B.; Gruber, Peter J.; Frederick, Sue Ellen

1976-01-01

Mildly disrupted cells of Chlamydomonas reinhardi Dangeard were incubated in a reaction medium containing glycolate, ferricyanide, and cupric ions, and then processed for electron microscopy. As a result of the cytochemical treatment, an electron opaque product was deposited specifically in the outer compartment of mitochondria; other cellular components, including microbodies, did not accumulate stain. Incubation with d-lactate yielded similar results, while treatment with l-lactate produced only a weak reaction. Oxamate, which inhibits glycolate dehydrogenase activity in cell-free extracts, also inhibited the cytochemical reaction. These findings demonstrate in situ that glycolate dehydrogenase is localized in mitochondria, and thus corroborate similar conclusions reached on the basis of enzymic studies of isolated algal organelles. Images PMID:16659670

Occupational exposure to glycol ethers: implications for occupational health nurses.

PubMed

Snow, J E

1994-09-01

1. Evaluation of workplace exposure to reproductive hazards is difficult and is often confounded by occupational exposure to multiple agents and exposure to non-occupational factors. 2. A growing body of evidence from animal and human study data supports a causal association between occupational exposure to certain glycol ethers and adverse reproductive outcomes. 3. Occupational health nurses providing services to employees exposed to glycol ethers should remain knowledgeable about the results of epidemiologic studies and current trends in the regulation of glycol ethers in industry. 4. Occupational health nurses are in a key position to reduce exposure to reproductive hazards by monitoring trends in group data and by implementing training and education programs to employees exposed to reproductive hazards.

Identification and In Silico Analysis of Major Redox Modulated Proteins from Brassica juncea Seedlings Using 2D Redox SDS PAGE (2-Dimensional Diagonal Redox Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis).

PubMed

Chaurasia, Satya Prakash; Deswal, Renu

2017-02-01

The thiol-disulphide exchange regulates the activity of proteins by redox modulation. Many studies to analyze reactive oxygen species (ROS), particularly, hydrogen peroxide (H 2 O 2 ) induced changes in the gene expression have been reported, but efforts to detect H 2 O 2 modified proteins are comparatively few. Two-dimensional diagonal redox sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) was used to detect polypeptides which undergo thiol-disulphide exchange in Brassica juncea seedlings following H 2 O 2 (10 mM) treatment for 30 min. Eleven redox responsive polypeptides were identified which included cruciferin, NLI [Nuclear LIM (Lin11, Isl-1 & Mec-3 domains)] interacting protein phosphatase, RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) large subunit, and myrosinase. Redox modulation of RuBisCO large subunit was further confirmed by western blotting. However, the small subunit of RuBisCO was not affected by these redox changes. All redox modulated targets except NLI interacting protein (although it contains two cysteines) showed oxidation sensitive cysteines by in silico analysis. Interestingly, interactome of cruciferin and myrosinase indicated that they may have additional function(s) beside their well-known roles in the seedling development and abiotic stress respectively. Cruciferin showed interactions with stress associated proteins like defensing-like protein 192 and 2-cys peroxiredoxin. Similarly, myrosinase showed interactions with nitrilase and cytochrome p450 which are involved in nitrogen metabolism and/or hormone biosynthesis. This simple procedure can be used to detect major stress mediated redox changes in other plants.

Redox flow cell energy storage systems

NASA Technical Reports Server (NTRS)

Thaller, L. H.

1979-01-01

The redox flow cell energy storage system being developed by NASA for use in remote power systems and distributed storage installations for electric utilities is presented. The system under consideration is an electrochemical storage device which utilizes the oxidation and reduction of two fully soluble redox couples (acidified chloride solutions of chromium and iron) as active electrode materials separated by a highly selective ion exchange membrane. The reactants are contained in large storage tanks and pumped through a stack of redox flow cells where the electrochemical reactions take place at porous carbon felt electrodes. Redox equipment has allowed the incorporation of state of charge readout, stack voltage control and system capacity maintenance (rebalance) devices to regulate cells in a stack jointly. A 200 W, 12 V system with a capacity of about 400 Wh has been constructed, and a 2 kW, 10kWh system is planned.

High energy density redox flow device

DOEpatents

Chiang, Yet-Ming; Carter, W. Craig; Ho, Bryan Y; Duduta, Mihai; Limthongkul, Pimpa

2014-05-13

Redox flow devices are described in which at least one of the positive electrode or negative electrode-active materials is a semi-solid or is a condensed ion-storing electroactive material, and in which at least one of the electrode-active materials is transported to and from an assembly at which the electrochemical reaction occurs, producing electrical energy. The electronic conductivity of the semi-solid is increased by the addition of conductive particles to suspensions and/or via the surface modification of the solid in semi-solids (e.g., by coating the solid with a more electron conductive coating material to increase the power of the device). High energy density and high power redox flow devices are disclosed. The redox flow devices described herein can also include one or more inventive design features. In addition, inventive chemistries for use in redox flow devices are also described.

Nitric-glycolic flowsheet testing for maximum hydrogen generation rate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martino, C. J.; Newell, J. D.; Williams, M. S.

The Defense Waste Processing Facility (DWPF) at the Savannah River Site is developing for implementation a flowsheet with a new reductant to replace formic acid. Glycolic acid has been tested over the past several years and found to effectively replace the function of formic acid in the DWPF chemical process. The nitric-glycolic flowsheet reduces mercury, significantly lowers the chemical generation of hydrogen and ammonia, allows purge reduction in the Sludge Receipt and Adjustment Tank (SRAT), stabilizes the pH and chemistry in the SRAT and the Slurry Mix Evaporator (SME), allows for effective adjustment of the SRAT/SME rheology, and is favorablemore » with respect to melter flammability. The objective of this work was to perform DWPF Chemical Process Cell (CPC) testing at conditions that would bound the catalytic hydrogen production for the nitric-glycolic flowsheet.« less

Sepiapterin Reductase Mediates Chemical Redox Cycling in Lung Epithelial Cells*

PubMed Central

Yang, Shaojun; Jan, Yi-Hua; Gray, Joshua P.; Mishin, Vladimir; Heck, Diane E.; Laskin, Debra L.; Laskin, Jeffrey D.

2013-01-01

In the lung, chemical redox cycling generates highly toxic reactive oxygen species that can cause alveolar inflammation and damage to the epithelium, as well as fibrosis. In this study, we identified a cytosolic NADPH-dependent redox cycling activity in mouse lung epithelial cells as sepiapterin reductase (SPR), an enzyme important for the biosynthesis of tetrahydrobiopterin. Human SPR was cloned and characterized. In addition to reducing sepiapterin, SPR mediated chemical redox cycling of bipyridinium herbicides and various quinones; this activity was greatest for 1,2-naphthoquinone followed by 9,10-phenanthrenequinone, 1,4-naphthoquinone, menadione, and 2,3-dimethyl-1,4-naphthoquinone. Whereas redox cycling chemicals inhibited sepiapterin reduction, sepiapterin had no effect on redox cycling. Additionally, inhibitors such as dicoumarol, N-acetylserotonin, and indomethacin blocked sepiapterin reduction, with no effect on redox cycling. Non-redox cycling quinones, including benzoquinone and phenylquinone, were competitive inhibitors of sepiapterin reduction but noncompetitive redox cycling inhibitors. Site-directed mutagenesis of the SPR C-terminal substrate-binding site (D257H) completely inhibited sepiapterin reduction but had minimal effects on redox cycling. These data indicate that SPR-mediated reduction of sepiapterin and redox cycling occur by distinct mechanisms. The identification of SPR as a key enzyme mediating chemical redox cycling suggests that it may be important in generating cytotoxic reactive oxygen species in the lung. This activity, together with inhibition of sepiapterin reduction by redox-active chemicals and consequent deficiencies in tetrahydrobiopterin, may contribute to tissue injury. PMID:23640889

Redox Proteomics Applied to the Thiol Secretome.

PubMed

Ghezzi, Pietro; Chan, Philippe

2017-03-01

Secreted proteins are important both as signaling molecules and potential biomarkers. Recent Advances: Protein can undergo different types of oxidation, both in physiological conditions or under oxidative stress. Several redox proteomics techniques have been successfully applied to the identification of glutathionylated proteins, an oxidative post-translational modification consisting in the formation of a mixed disulfide between a protein cysteine and glutathione. Redox proteomics has also been used to study other forms of protein oxidation. Because of the highest proportion of free cysteines in the cytosol, redox proteomics of protein thiols has focused, so far, on intracellular proteins. However, plasma proteins, such as transthyretin and albumin, have been described as glutathionylated or cysteinylated. The present review discusses the redox state of protein cysteines in relation to their cellular distribution. We describe the various approaches used to detect secreted glutathionylated proteins, the only thiol modification studied so far in secreted proteins, and the specific problems presented in the study of the secretome. This review focusses on glutathionylated proteins secreted under inflammatory conditions and that may act as soluble mediators (cytokines). Future studies on the redox secretome (including other forms of oxidation) might identify new soluble mediators and biomarkers of oxidative stress. Antioxid. Redox Signal. 26, 299-312.

Subcellular Redox Targeting: Bridging in Vitro and in Vivo Chemical Biology.

PubMed

Long, Marcus J C; Poganik, Jesse R; Ghosh, Souradyuti; Aye, Yimon

2017-03-17

Networks of redox sensor proteins within discrete microdomains regulate the flow of redox signaling. Yet, the inherent reactivity of redox signals complicates the study of specific redox events and pathways by traditional methods. Herein, we review designer chemistries capable of measuring flux and/or mimicking subcellular redox signaling at the cellular and organismal level. Such efforts have begun to decipher the logic underlying organelle-, site-, and target-specific redox signaling in vitro and in vivo. These data highlight chemical biology as a perfect gateway to interrogate how nature choreographs subcellular redox chemistry to drive precision redox biology.

Redox regulation of neuronal voltage-gated calcium channels.

PubMed

Todorovic, Slobodan M; Jevtovic-Todorovic, Vesna

2014-08-20

Voltage-gated calcium channels are ubiquitously expressed in neurons and are key regulators of cellular excitability and synaptic transmitter release. There is accumulating evidence that multiple subtypes of voltage-gated calcium channels may be regulated by oxidation and reduction. However, the redox mechanisms involved in the regulation of channel function are not well understood. Several studies have established that both T-type and high-voltage-activated subtypes of voltage-gated calcium channel can be redox-regulated. This article reviews different mechanisms that can be involved in redox regulation of calcium channel function and their implication in neuronal function, particularly in pain pathways and thalamic oscillation. A current critical issue in the field is to decipher precise mechanisms of calcium channel modulation via redox reactions. In this review we discuss covalent post-translational modification via oxidation of cysteine molecules and chelation of trace metals, and reactions involving nitric oxide-related molecules and free radicals. Improved understanding of the roles of redox-based reactions in regulation of voltage-gated calcium channels may lead to improved understanding of novel redox mechanisms in physiological and pathological processes. Identification of redox mechanisms and sites on voltage-gated calcium channel may allow development of novel and specific ion channel therapies for unmet medical needs. Thus, it may be possible to regulate the redox state of these channels in treatment of pathological process such as epilepsy and neuropathic pain.

Bicarbonate Induced Redox Proteome Changes in Arabidopsis Suspension Cells.

PubMed

Yin, Zepeng; Balmant, Kelly; Geng, Sisi; Zhu, Ning; Zhang, Tong; Dufresne, Craig; Dai, Shaojun; Chen, Sixue

2017-01-01

Climate change as a result of increasing atmospheric CO 2 affects plant growth and productivity. CO 2 is not only a carbon donor for photosynthesis but also an environmental signal that can perturb cellular redox homeostasis and lead to modifications of redox-sensitive proteins. Although redox regulation of protein functions has emerged as an important mechanism in several biological processes, protein redox modifications and how they function in plant CO 2 response remain unclear. Here a new iodoTMTRAQ proteomics technology was employed to analyze changes in protein redox modifications in Arabidopsis thaliana suspension cells in response to bicarbonate (mimic of elevated CO 2 ) in a time-course study. A total of 47 potential redox-regulated proteins were identified with functions in carbohydrate and energy metabolism, transport, ROS scavenging, cell structure modulation and protein turnover. This inventory of previously unknown redox responsive proteins in Arabidopsis bicarbonate responses lays a foundation for future research toward understanding the molecular mechanisms underlying plant CO 2 responses.

Bicarbonate Induced Redox Proteome Changes in Arabidopsis Suspension Cells

PubMed Central

Yin, Zepeng; Balmant, Kelly; Geng, Sisi; Zhu, Ning; Zhang, Tong; Dufresne, Craig; Dai, Shaojun; Chen, Sixue

2017-01-01

Climate change as a result of increasing atmospheric CO2 affects plant growth and productivity. CO2 is not only a carbon donor for photosynthesis but also an environmental signal that can perturb cellular redox homeostasis and lead to modifications of redox-sensitive proteins. Although redox regulation of protein functions has emerged as an important mechanism in several biological processes, protein redox modifications and how they function in plant CO2 response remain unclear. Here a new iodoTMTRAQ proteomics technology was employed to analyze changes in protein redox modifications in Arabidopsis thaliana suspension cells in response to bicarbonate (mimic of elevated CO2) in a time-course study. A total of 47 potential redox-regulated proteins were identified with functions in carbohydrate and energy metabolism, transport, ROS scavenging, cell structure modulation and protein turnover. This inventory of previously unknown redox responsive proteins in Arabidopsis bicarbonate responses lays a foundation for future research toward understanding the molecular mechanisms underlying plant CO2 responses. PMID:28184230

Redox polymer electrodes for advanced batteries

DOEpatents

Gregg, B.A.; Taylor, A.M.

1998-11-24

Advanced batteries having a long cycle lifetime are provided. More specifically, the present invention relates to electrodes made from redox polymer films and batteries in which either the positive electrode, the negative electrode, or both, comprise redox polymers. Suitable redox polymers for this purpose include pyridyl or polypyridyl complexes of transition metals like iron, ruthenium, osmium, chromium, tungsten and nickel; porphyrins (either free base or metallo derivatives); phthalocyanines (either free base or metallo derivatives); metal complexes of cyclams, such as tetraazacyclotetradecane; metal complexes of crown ethers and metallocenes such as ferrocene, cobaltocene and ruthenocene. 2 figs.

Neutral Red and Ferroin as Reversible and Rapid Redox Materials for Redox Flow Batteries.

PubMed

Hong, Jeehoon; Kim, Ketack

2018-06-11

Neutral red and ferroin are used as redox indicators (RINs) in potentiometric titrations. The rapid response and reversibility that are prerequisites for RINs are also desirable properties for the active materials in redox flow batteries (RFBs). This study describes the electrochemical properties of ferroin and neutral red as a redox pair. The rapid reaction rates of the RINs allow a cell to run at a rate of 4 C with 89 % capacity retention after the 100 th  cycle. The diffusion coefficients, electrode reaction rates, and solubilities of the RINs were determined. The electron-transfer rate constants of ferroin and neutral red are 0.11 and 0.027 cm s -1 , respectively, which are greater than those of the components of all-vanadium and Zn/Br 2 cells. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Redox Homeostasis in Pancreatic β Cells

PubMed Central

Ježek, Petr; Dlasková, Andrea; Plecitá-Hlavatá, Lydie

2012-01-01

We reviewed mechanisms that determine reactive oxygen species (redox) homeostasis, redox information signaling and metabolic/regulatory function of autocrine insulin signaling in pancreatic β cells, and consequences of oxidative stress and dysregulation of redox/information signaling for their dysfunction. We emphasize the role of mitochondrion in β cell molecular physiology and pathology, including the antioxidant role of mitochondrial uncoupling protein UCP2. Since in pancreatic β cells pyruvate cannot be easily diverted towards lactate dehydrogenase for lactate formation, the respiration and oxidative phosphorylation intensity are governed by the availability of glucose, leading to a certain ATP/ADP ratio, whereas in other cell types, cell demand dictates respiration/metabolism rates. Moreover, we examine the possibility that type 2 diabetes mellitus might be considered as an inevitable result of progressive self-accelerating oxidative stress and concomitantly dysregulated information signaling in peripheral tissues as well as in pancreatic β cells. It is because the redox signaling is inherent to the insulin receptor signaling mechanism and its impairment leads to the oxidative and nitrosative stress. Also emerging concepts, admiting participation of redox signaling even in glucose sensing and insulin release in pancreatic β cells, fit in this view. For example, NADPH has been firmly established to be a modulator of glucose-stimulated insulin release. PMID:23304259

Microfluidic redox battery.

PubMed

Lee, Jin Wook; Goulet, Marc-Antoni; Kjeang, Erik

2013-07-07

A miniaturized microfluidic battery is proposed, which is the first membraneless redox battery demonstrated to date. This unique concept capitalizes on dual-pass flow-through porous electrodes combined with stratified, co-laminar flow to generate electrical power on-chip. The fluidic design is symmetric to allow for both charging and discharging operations in forward, reverse, and recirculation modes. The proof-of-concept device fabricated using low-cost materials integrated in a microfluidic chip is shown to produce competitive power levels when operated on a vanadium redox electrolyte. A complete charge/discharge cycle is performed to demonstrate its operation as a rechargeable battery, which is an important step towards providing sustainable power to lab-on-a-chip and microelectronic applications.

Redox hydrogel based bienzyme electrode for L-glutamate monitoring.

PubMed

Belay, A; Collins, A; Ruzgas, T; Kissinger, P T; Gorton, L; Csöregi, E

1999-02-01

Amperometric bienzyme electrodes based on coupled L-glutamate oxidase (GlOx) and horseradish peroxidase (HRP) were constructed for the direct monitoring of L-glutamate in a flow injection (FI)-system. The bienzyme electrodes were constructed by coating solid graphite rods with a premixed solution containing GlOx and HRP crosslinked with a redox polymer formed of poly(1-vinylimidazole) complexed with (osmium (4-4'-dimethylbpy)2 Cl)II/III. Poly(ethylene glycol) diglycidyl ether (PEGDGE) was used as the crosslinker and the modified electrodes were inserted as the working electrode in a conventional three electrode flow through amperometric cell operated at -0.05 V versus Ag¿AgCl (0.1 M KCl). The bienzyme electrode was optimized with regard to wire composition, Os-loading of the wires, enzyme ratios, coating procedure, flow rate, effect of poly(ethyleneimine) addition, etc. The optimized electrodes were characterized by a sensitivity of 88.36 +/- 0.14 microA mM(-1) cm(-2), a detection limit of 0.3 microM (calculated as three times the signal-to-noise ratio), a response time of less than 10 s and responded linearly between 0.3 and 250 microM (linear regression coefficient = 0.999) with an operational stability of only 3% sensitivity loss during 8 h of continuous FI operation at a sample throughput of 30 injections h(-1).

Surface and Electrochemical Properties of Polymer Brush-Based Redox Poly(Ionic Liquid).

PubMed

Bui-Thi-Tuyet, Van; Trippé-Allard, Gaëlle; Ghilane, Jalal; Randriamahazaka, Hyacinthe

2016-10-26

Redox-active poly(ionic liquid) poly(3-(2-methacryloyloxy ethyl)-1-(N-(ferrocenylmethyl) imidazolium bis(trifluoromethylsulfonyl)imide deposited onto electrode surfaces has been prepared using surface-initiated atom transfer radical polymerization SI-ATRP. The process starts by electrochemical immobilization of initiator layer, and then methacrylate monomer carrying ferrocene and imidazolium units is polymerized in ionic liquid media via SI-ATRP process. The surfaces analyses of the polymer exhibit a well-defined polymer brushlike structure and confirm the presence of ferrocene and ionic moieties within the film. Furthermore, the electrochemical investigations of poly(redox-active ionic liquid) in different media demonstrate that the electron transfer is not restricted by the rate of counterion migration into/out of the polymer. The attractive electrochemical performance of these materials is further demonstrated by performing electrochemical measurement, of poly(ferrocene ionic liquid), in solvent-free electrolyte. The facile synthesis of such highly ordered electroactive materials based ionic liquid could be useful for the fabrication of nanostructured electrode suitable for performing electrochemistry in solvent free electrolyte. We also demonstrate possible applications of the poly(FcIL) as electrochemically reversible surface wettability system and as electrochemical sensor for the catalytic activity toward the oxidation of tyrosine.

Unusual thiol-based redox metabolism of parasitic flukes.

PubMed

Tripathi, Timir; Suttiprapa, Sutas; Sripa, Banchob

2017-08-01

Parasitic flukes are exposed to free radicals and, to a greater extent, reactive oxygen species (ROS) during their life cycle. Despite being relentlessly exposed to ROS released by activated immune cells, these parasites can survive for many years in the host. Cellular thiol-based redox metabolism plays a crucial role in parasite survival within their hosts. Evidence shows that oxidative stress and redox homeostasis maintenance are important clinical and pathobiochemical as well as effective therapeutic principles in various diseases. The characterization of redox and antioxidant enzymes is likely to yield good target candidates for novel drugs and vaccines. The absence of active catalase in fluke parasites offers great potential for the development of chemotherapeutic agents that act by perturbing the redox equilibrium of the cell. One of the redox-sensitive enzymes, thioredoxin glutathione reductase (TGR), has been accepted as a drug target against blood fluke infections, and related clinical trials are in progress. TGR is the sole enzyme responsible for Trx and GSH reduction in parasitic flukes. The availability of helminth genomes has accelerated the research on redox metabolism of flukes; however, significant achievements have yet to be attained. The present review summarizes current knowledge on the redox and antioxidant system of the parasitic flukes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Managing the cellular redox hub in photosynthetic organisms.

PubMed

Foyer, Christine H; Noctor, Graham

2012-02-01

Light-driven redox chemistry is a powerful source of redox signals that has a decisive input into transcriptional control within the cell nucleus. Like photosynthetic electron transport pathways, the respiratory electron transport chain exerts a profound control over gene function, in order to balance energy (reductant and ATP) supply with demand, while preventing excessive over-reduction or over-oxidation that would be adversely affect metabolism. Photosynthetic and respiratory redox chemistries are not merely housekeeping processes but they exert a controlling influence over every aspect of plant biology, participating in the control of gene transcription and translation, post-translational modifications and the regulation of assimilatory reactions, assimilate partitioning and export. The number of processes influenced by redox controls and signals continues to increase as do the components that are recognized participants in the associated signalling pathways. A step change in our understanding of the overall importance of the cellular redox hub to plant cells has occurred in recent years as the complexity of the management of the cellular redox hub in relation to metabolic triggers and environmental cues has been elucidated. This special issue describes aspects of redox regulation and signalling at the cutting edge of current research in this dynamic and rapidly expanding field. © 2011 Blackwell Publishing Ltd.

Redox Modulations, Antioxidants, and Neuropsychiatric Disorders

PubMed Central

Fraunberger, Erik A.; Laliberté, Victoria L. M.; Duong, Angela; Andreazza, Ana C.

2016-01-01

Although antioxidants, redox modulations, and neuropsychiatric disorders have been widely studied for many years, the field would benefit from an integrative and corroborative review. Our primary objective is to delineate the biological significance of compounds that modulate our redox status (i.e., reactive species and antioxidants) as well as outline their current role in brain health and the impact of redox modulations on the severity of illnesses. Therefore, this review will not enter into the debate regarding the perceived medical legitimacy of antioxidants but rather seek to clarify their abilities and limitations. With this in mind, antioxidants may be interpreted as natural products with significant pharmacological actions in the body. A renewed understanding of these often overlooked compounds will allow us to critically appraise the current literature and provide an informed, novel perspective on an important healthcare issue. In this review, we will introduce the complex topics of redox modulations and their role in the development of select neuropsychiatric disorders. PMID:26640614

Improving gas dehydrator efficiency; Glycol losses from dehydrator solved by mist eliminator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Franke, S.; Neal, R.; Patel, K.

1989-07-01

Triethylene glycol losses from a natural gas dehydrator unit were costing Winnie Pipeline Co. well over $100/day. Several possible causes had been investigated, and a second, smaller unit had been added because insufficient capacity was thought to cause glycol carryover from the contactor. Eventually, glycol losses were virtually eliminated by replacing the standard mist eliminator pad in the top of the contactor tower with a higher-efficiency type. Use of this type of pad is discussed in this paper.

Redox Strategies for Crop Improvement.

PubMed

Kerchev, Pavel; De Smet, Barbara; Waszczak, Cezary; Messens, Joris; Van Breusegem, Frank

2015-11-10

Recently, the agro-biotech industry has been driven by overcoming the limitations imposed by fluctuating environmental stress conditions on crop productivity. A common theme among (a)biotic stresses is the perturbation of the redox homeostasis. As a strategy to engineer stress-tolerant crops, many approaches have been centered on restricting the negative impact of reactive oxygen species (ROS) accumulation. In this study, we discuss the scientific background of the existing redox-based strategies to improve crop performance and quality. In this respect, a special focus goes to summarizing the current patent landscape because this aspect is very often ignored, despite constituting the forefront of applied research. The current increased understanding of ROS acting as signaling molecules has opened new avenues to exploit redox biology for crop improvement required for sustainable food security.

Electronegativity and redox reactions.

PubMed

Miranda-Quintana, Ramón Alain; Martínez González, Marco; Ayers, Paul W

2016-08-10

Using the maximum hardness principle, we show that the oxidation potential of a molecule increases as its electronegativity increases and also increases as its electronegativity in its oxidized state increases. This insight can be used to construct a linear free energy relation for the oxidation potential, which we train on a set of 31 organic redox couples and test on a set of 10 different redox reactions. Better results are obtained when the electronegativity of the oxidized/reduced reagents are adjusted to account for the reagents' interaction with their chemical environment.

Redox-Assisted Protein Folding Systems in Eukaryotic Parasites

PubMed Central

Haque, Saikh Jaharul; Majumdar, Tanmay

2012-01-01

Abstract Significance: The cysteine (Cys) residues of proteins play two fundamentally important roles. They serve as sites of post-translational redox modifications as well as influence the conformation of the protein through the formation of disulfide bonds. Recent Advances: Redox-related and redox-associated protein folding in protozoan parasites has been found to be a major mode of regulation, affecting myriad aspects of the parasitic life cycle, host-parasite interactions, and the disease pathology. Available genome sequences of various parasites have begun to complement the classical biochemical and enzymological studies of these processes. In this article, we summarize the reversible Cys disulfide (S-S) bond formation in various classes of strategically important parasitic proteins, and its structural consequence and functional relevance. Critical Issues: Molecular mechanisms of folding remain under-studied and often disconnected from functional relevance. Future Directions: The clinical benefit of redox research will require a comprehensive characterization of the various isoforms and paralogs of the redox enzymes and their concerted effect on the structure and function of the specific parasitic client proteins. Antioxid. Redox Signal. 17, 674–683. PMID:22122448

Hydrogen production through aqueous-phase reforming of ethylene glycol in a washcoated microchannel.

PubMed

D'Angelo, M Fernanda Neira; Ordomsky, Vitaly; Paunovic, Violeta; van der Schaaf, John; Schouten, Jaap C; Nijhuis, T Alexander

2013-09-01

Aqueous-phase reforming (APR) of biocarbohydrates is conducted in a catalytically stable washcoated microreactor where multiphase hydrogen removal enhances hydrogen efficiency. Single microchannel experiments are conducted following a simplified model based on the microreactor concept. A coating method to deposit a Pt-based catalyst on the microchannel walls is selected and optimized. APR reactivity tests are performed by using ethylene glycol as the model compound. Optimum results are achieved with a static washcoating technique; a highly uniform and well adhered 5 μm layer is deposited on the walls of a 320 μm internal diameter (ID) microchannel in one single step. During APR of ethylene glycol, the catalyst layer exhibits high stability over 10 days after limited initial deactivation. The microchannel presents higher conversion and selectivity to hydrogen than a fixed-bed reactor. The benefits of using a microreactor for APR can be further enhanced by utilizing increased Pt loadings, higher reaction temperatures, and larger carbohydrates (e.g., glucose). The use of microtechnology for aqueous-phase reforming will allow for a great reduction in the reformer size, thus rendering it promising for distributed hydrogen production. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photopolymerization of N,N-dimethylaminobenzyl alcohol as amine co-initiator for light-cured dental resins.

PubMed

Schroeder, Walter F; Cook, Wayne D; Vallo, Claudia I

2008-05-01

The present study was carried out in order to assess the suitability of N,N-dimethylaminobenzyl alcohol (DMOH) as co-initiator of camphorquinone (CQ) and 1-phenyl-1,2-propanedione (PPD) in light-cured dental resins. DMOH was synthesized and used as co-initiator for the photopolymerization of a model resin based on {2,2-bis[4-(2-hydroxy-3-methacryloxyprop-1-oxy)phenyl]propane} (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA). Experimental formulations containing CQ or PPD in combination with DMOH at different concentrations were studied. The photopolymerization was carried out by means of a commercial light-emitting diode (LED) curing unit. The evolution of double bonds consumption versus irradiation time was followed by near-infrared spectroscopy (NIR). The photon absorption efficiency (PAE) of the photopolymerization process was calculated from the spectral distribution of the LED unit and the molar absorption coefficient distributions of PPD and CQ. DMOH is an efficient photoreducer of CQ and PPD resulting in higher polymerization rate and higher double bond conversion compared with dimethylaminoethylmethacrylate. The PAE for PPD was higher than that for CQ. However, the polymerization initiated by PPD progressed at a lower rate and exhibited lower values of final conversion compared with the resins containing CQ. This observation indicates that the lower polymerization rate of the PPD/amine system should be explained in terms of the mechanism of generating primary radicals by PPD, which is less efficient compared with CQ. The DMOH/benzoyl peroxide redox system, has recently been proposed as a more biocompatible accelerator for the polymerization of bone cements based on poly(methyl methacrylate), because cytotoxity tests have demonstrated that DMOH possesses better biocompatibility properties compared with traditional tertiary amines. The results obtained in the present study reveal the suitability of the CQ/DMOH initiator system for the polymerization of

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

Propylene Glycol-Related Delirium After Esmolol Infusion.

PubMed

Kapitein, Berber S; Biesmans, Renee S C G; van der Sijs, Heleen S I; de Wildt, Saskia S N

2014-07-01

Excipients used in oral or intravenous preparations may cause serious adverse events. We present the case of a 15-year-old boy with hypertrophic cardiomyopathy. In the pediatric intensive care unit, he received high doses of continuous intravenous esmolol (range = 20-400 µg/kg/min) for cardiac rhythm control. After a few days he developed a delirium not responding to high doses of antipsychotics or discontinuation of benzodiazepines. We eventually realized that the IV esmolol formulation contained high doses of propylene glycol and ethanol, which may accumulate after prolonged infusion and cause intoxication. Intoxication with propylene glycolcan cause neuropsychiatric symptoms. The boy's propylene glycol plasma concentration was approximately 4 g/L, whereas clinical symptoms arise at concentrations above 1 to 1.44 g/L. Application of the Naranjo adverse drug reaction probability scale suggested a probable relationship (score 6) between the propylene glycol infusion and the delirium. After discontinuation of esmolol, the delirium disappeared spontaneously. This is the first case describing excipient toxicity of esmolol, with an objective causality assessment revealing a probable relationship for the adverse event-namely, delirium-and esmolol. Although excipient toxicity is a well-known adverse drug reaction, this case stresses the importance for easily available information for and education of physicians. © The Author(s) 2014.

Final report on the safety assessment of Triethylene Glycol and PEG-4.

PubMed

2006-01-01

Triethylene Glycol and PEG-4 (polyethylene glycol) are polymers of ethylene oxide alcohol. Triethylene Glycol is a specific three-unit chain, whereas PEG-4 is a polymer with an average of four units, but may contain polymers ranging from two to eight ethylene oxide units. In the same manner, other PEG compounds, e.g., PEG-6, are mixtures and likely contain some Triethylene Glycol and PEG-4. Triethylene Glycol is a fragrance ingredient and viscosity decreasing agent in cosmetic formulations, with a maximum concentration of use of 0.08% in skin-cleansing products. Following oral doses, Triethylene Glycol and its metabolites are excreted primarily in urine, with small amounts released in feces and expired air. With oral LD50 values in rodents from 15 to 22 g/kg, this compound has little acute toxicity. Rats given short term oral doses of 3% in water showed no signs of toxicity, whereas all rats given 10% died by the 12th day of exposure. At levels up to 1 g/m3, rats exposed to aerosolized Triethylene Glycol for 6 h per day for 9 days showed no signs of toxicity. Rats fed a diet containing 4% Triethylene Glycol for 2 years showed no signs of toxicity. There were no treatment-related effects on rats exposed to supersaturated Triethylene Glycol vapor for 13 months nor in rats that consumed 0.533 cc Triethylene Glycol per day in drinking water for 13 months. Triethylene Glycol was not irritating to the skin of rabbits and produced only minimal injury to the eye. In reproductive and developmental toxicity studies in rats and mice, Triethylene Glycol did not produce biologically significant embryotoxicity or teratogenicity. However, some maternal toxicity was seen in dams given 10 ml/kg/day during gestation. Triethylene Glycol was not mutagenic or genotoxic in Ames-type assays, the Chinese hamster ovary mutation assay, and the sister chromatid exchange assays. PEG-4 is a humectant and solvent in cosmetic products, with a maximum concentration of use of 20% in the "other

Redox inactive metal ion triggered N-dealkylation by an iron catalyst with dioxygen activation: a lesson from lipoxygenases.

PubMed

Zhang, Jisheng; Wang, Yujuan; Luo, Nengchao; Chen, Zhuqi; Wu, Kangbing; Yin, Guochuan

2015-06-07

Utilization of dioxygen as the terminal oxidant at ambient temperature is always a challenge in redox chemistry, because it is hard to oxidize a stable redox metal ion like iron(III) to its high oxidation state to initialize the catalytic cycle. Inspired by the dioxygenation and co-oxidase activity of lipoxygenases, herein, we introduce an alternative protocol to activate the sluggish iron(III) species with non-redox metal ions, which can promote its oxidizing power to facilitate substrate oxidation with dioxygen, thus initializing the catalytic cycle. In oxidations of N,N-dimethylaniline and its analogues, adding Zn(OTf)2 to the [Fe(TPA)Cl2]Cl catalyst can trigger the amine oxidation with dioxygen, whereas [Fe(TPA)Cl2]Cl alone is very sluggish. In stoichiometric oxidations, it has also been confirmed that the presence of Zn(OTf)2 can apparently improve the electron transfer capability of the [Fe(TPA)Cl2]Cl complex. Experiments using different types of substrates as trapping reagents disclosed that the iron(IV) species does not occur in the catalytic cycle, suggesting that oxidation of amines is initialized by electron transfer rather than hydrogen abstraction. Combined experiments from UV-Vis, high resolution mass spectrometry, electrochemistry, EPR and oxidation kinetics support that the improved electron transfer ability of iron(III) species originates from its interaction with added Lewis acids like Zn(2+) through a plausible chloride or OTf(-) bridge, which has promoted the redox potential of iron(III) species. The amine oxidation mechanism was also discussed based on the available data, which resembles the co-oxidase activity of lipoxygenases in oxidative dealkylation of xenobiotic metabolisms where an external electron donor is not essential for dioxygen activation.

Ethylene glycol poisoning in three dogs: Importance of early diagnosis and role of hemodialysis as a treatment option.

PubMed

Schweighauser, A; Francey, T

2016-02-01

Poisoning with ethylene glycol as contained in antifreeze can rapidly lead to irreversible acute renal failure and other organ damage. It carries a grave prognosis unless diagnosed early and adequate treatment is initiated within 8 hours of ingestion. Toxicity of ethylene glycol is related to the production of toxic metabolites by the enzyme alcohol dehydrogenase (ADH), leading to early signs of severe polyuria (PU) and polydipsia (PD), gastritis, ataxia and central nervous depression, followed by progressive dehydration, and ultimately oligoanuric renal failure. In addition to general supportive care, therapeutic interventions must include either antidotes blocking ADH-mediated metabolism or blood purification techniques to remove both the parent compound and the toxic metabolites. The goal of this case report is to describe three cases of acute antifreeze intoxication in dogs, and to discuss treatment options available for this poisoning.

Mesoporous tungsten oxynitride as electrocatalyst for promoting redox reactions of vanadium redox couple and performance of vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Lee, Wonmi; Jo, Changshin; Youk, Sol; Shin, Hun Yong; Lee, Jinwoo; Chung, Yongjin; Kwon, Yongchai

2018-01-01

For enhancing the performance of vanadium redox flow battery (VRFB), a sluggish reaction rate issue of V2+/V3+ redox couple evaluated as the rate determining reaction should be addressed. For doing that, mesoporous tungsten oxide (m-WO3) and oxyniride (m-WON) structures are proposed as the novel catalysts, while m-WON is gained by NH3 heat treatment of m-WO3. Their specific surface area, crystal structure, surface morphology and component analysis are measured using BET, XRD, TEM and XPS, while their catalytic activity for V2+/V3+ redox reaction is electrochemically examined. As a result, the m-WON shows higher peak current, smaller peak potential difference, higher electron transfer rate constant and lower charge transfer resistance than other catalysts, like the m-WO3, WO3 nanoparticle and mesoporous carbon, proving that it is superior catalyst. Regarding the charge-discharge curve tests, the VRFB single cell employing the m-WON demonstrates high voltage and energy efficiencies, high specific capacity and low capacity loss rate. The excellent results of m-WON are due to the reasons like (i) reduced energy band gap, (ii) reaction familiar surface functional groups and (ii) greater electronegativity.

Impact of scaling on the nitric-glycolic acid flowsheet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambert, D.

Savannah River Remediation (SRR) is considering using glycolic acid as a replacement for formic acid in Sludge Receipt and Adjustment Tank (SRAT) processing in the Defense Waste Processing Facility (DWPF). Catalytic decomposition of formic acid is responsible for the generation of hydrogen, a potentially flammable gas, during processing. To prevent the formation of a flammable mixture in the offgas, an air purge is used to dilute the hydrogen concentration below the 60% of the Composite Lower Flammability Limit (CLFL). The offgas is continuously monitored for hydrogen using Gas Chromatographs (GCs). Since formic acid is much more volatile and toxic thanmore » glycolic acid, a formic acid spill would lead to the release of much larger quantities to the environment. Switching from formic acid to glycolic acid is expected to eliminate the hydrogen flammability hazard leading to lower air purges, thus downgrading of Safety Significant GCs to Process Support GCs, and minimizing the consequence of a glycolic acid tank leak in DWPF. Overall this leads to a reduction in process operation costs and an increase in safety margin. Experiments were completed at three different scales to demonstrate that the nitric-glycolic acid flowsheet scales from the 4-L lab scale to the 22-L bench scale and 220-L engineering scale. Ten process demonstrations of the sludge-only flowsheet for SRAT and Slurry Mix Evaporator (SME) cycles were performed using Sludge Batch 8 (SB8)-Tank 40 simulant. No Actinide Removal Process (ARP) product or strip effluent was added during the runs. Six experiments were completed at the 4-L scale, two experiments were completed at the 22-L scale, and two experiments were completed at the 220-L scale. Experiments completed at the 4-L scale (100 and 110% acid stoichiometry) were repeated at the 22-L and 220-L scale for scale comparisons.« less

Inert Reassessment Document for Ethylene Glycol

EPA Pesticide Factsheets

Ethylene Glycol has many uses and are also used as antifreeze and deicers, as solvents, humectants, as chemical intermediates in the synthesis of other chemicals, and as components of many products such as brake fluids, lubricants, inks,and lacquers.

Propylene Glycol Poisoning From Excess Whiskey Ingestion: A Case of High Osmolal Gap Metabolic Acidosis.

PubMed

Cunningham, Courtney A; Ku, Kevin; Sue, Gloria R

2015-01-01

In this report, we describe a case of high anion gap metabolic acidosis with a significant osmolal gap attributed to the ingestion of liquor containing propylene glycol. Recently, several reports have characterized severe lactic acidosis occurring in the setting of iatrogenic unintentional overdosing of medications that use propylene glycol as a diluent, including lorazepam and diazepam. To date, no studies have explored potential effects of excess propylene glycol in the setting of alcohol intoxication. Our patient endorsed drinking large volumes of cinnamon flavored whiskey, which was likely Fireball Cinnamon Whisky. To our knowledge, this is the first case of propylene glycol toxicity from an intentional ingestion of liquor containing propylene glycol.

Sources of propylene glycol and glycol ethers in air at home.

PubMed

Choi, Hyunok; Schmidbauer, Norbert; Spengler, John; Bornehag, Carl-Gustaf

2010-12-01

Propylene glycol and glycol ether (PGE) in indoor air have recently been associated with asthma and allergies as well as sensitization in children. In this follow-up report, sources of the PGEs in indoor air were investigated in 390 homes of pre-school age children in Sweden. Professional building inspectors examined each home for water damages, mold odour, building's structural characteristics, indoor temperature, absolute humidity and air exchange rate. They also collected air and dust samples. The samples were analyzed for four groups of volatile organic compounds (VOCs) and semi-VOCs (SVOCs), including summed concentrations of 16 PGEs, 8 terpene hydrocarbons, 2 Texanols, and the phthalates n-butyl benzyl phthalate (BBzP), and di(2-ethylhexyl)phthalate (DEHP). Home cleaning with water and mop ≥ once/month, repainting ≥ one room prior to or following the child's birth, and "newest" surface material in the child's bedroom explained largest portion of total variability in PGE concentrations. High excess indoor humidity (g/m³) additionally contributed to a sustained PGE levels in indoor air far beyond several months following the paint application. No behavioral or building structural factors, except for water-based cleaning, predicted an elevated terpene level in air. No significant predictor of Texanols emerged from our analysis. Overall disparate sources and low correlations among the PGEs, terpenes, Texanols, and the phthalates further confirm the lack of confounding in the analysis reporting the associations of the PGE and the diagnoses of asthma, rhinitis, and eczema, respectively.

Bifunctional redox tagging of carbon nanoparticles

NASA Astrophysics Data System (ADS)

Poon, Jeffrey; Batchelor-McAuley, Christopher; Tschulik, Kristina; Palgrave, Robert G.; Compton, Richard G.

2015-01-01

Despite extensive work on the controlled surface modification of carbon with redox moieties, to date almost all available methodologies involve complex chemistry and are prone to the formation of polymerized multi-layer surface structures. Herein, the facile bifunctional redox tagging of carbon nanoparticles (diameter 27 nm) and its characterization is undertaken using the industrial dye Reactive Blue 2. The modification route is demonstrated to be via exceptionally strong physisorption. The modified carbon is found to exhibit both well-defined oxidative and reductive voltammetric redox features which are quantitatively interpreted. The method provides a generic approach to monolayer modifications of carbon and carbon nanoparticle surfaces.

Vascular remodeling: A redox-modulated mechanism of vessel caliber regulation.

PubMed

Tanaka, Leonardo Y; Laurindo, Francisco R M

2017-08-01

Vascular remodeling, i.e. whole-vessel structural reshaping, determines lumen caliber in (patho)physiology. Here we review mechanisms underlying vessel remodeling, with emphasis in redox regulation. First, we discuss confusing terminology and focus on strictu sensu remodeling. Second, we propose a mechanobiological remodeling paradigm based on the concept of tensional homeostasis as a setpoint regulator. We first focus on shear-mediated models as prototypes of remodeling closely dominated by highly redox-sensitive endothelial function. More detailed discussions focus on mechanosensors, integrins, extracellular matrix, cytoskeleton and inflammatory pathways as potential of mechanisms potentially coupling tensional homeostasis to redox regulation. Further discussion of remodeling associated with atherosclerosis and injury repair highlights important aspects of redox vascular responses. While neointima formation has not shown consistent responsiveness to antioxidants, vessel remodeling has been more clearly responsive, indicating that despite the multilevel redox signaling pathways, there is a coordinated response of the whole vessel. Among mechanisms that may orchestrate redox pathways, we discuss roles of superoxide dismutase activity and extracellular protein disulfide isomerase. We then discuss redox modulation of aneurysms, a special case of expansive remodeling. We propose that the redox modulation of vascular remodeling may reflect (1) remodeling pathophysiology is dominated by a particularly redox-sensitive cell type, e.g., endothelial cells (2) redox pathways are temporospatially coordinated at an organ level across distinct cellular and acellular structures or (3) the tensional homeostasis setpoint is closely connected to redox signaling. The mechanobiological/redox model discussed here can be a basis for improved understanding of remodeling and helps clarifying mechanisms underlying prevalent hard-to-treat diseases. Copyright © 2017 Elsevier Inc. All

Redox-Based Regulation of Bacterial Development and Behavior.

PubMed

Sporer, Abigail J; Kahl, Lisa J; Price-Whelan, Alexa; Dietrich, Lars E P

2017-06-20

Severe changes in the environmental redox potential, and resulting alterations in the oxidation states of intracellular metabolites and enzymes, have historically been considered negative stressors, requiring responses that are strictly defensive. However, recent work in diverse organisms has revealed that more subtle changes in the intracellular redox state can act as signals, eliciting responses with benefits beyond defense and detoxification. Changes in redox state have been shown to influence or trigger chromosome segregation, sporulation, aerotaxis, and social behaviors, including luminescence as well as biofilm establishment and dispersal. Connections between redox state and complex behavior allow bacteria to link developmental choices with metabolic state and coordinate appropriate responses. Promising future directions for this area of study include metabolomic analysis of species- and condition-dependent changes in metabolite oxidation states and elucidation of the mechanisms whereby the redox state influences circadian regulation.

Redox flow batteries having multiple electroactive elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wei; Li, Liyu; Yang, Zhenguo

Introducing multiple redox reactions with a suitable voltage range can improve the energy density of redox flow battery (RFB) systems. One example includes RFB systems utilizing multiple redox pairs in the positive half cell, the negative half cell, or in both. Such RFB systems can have a negative electrolyte, a positive electrolyte, and a membrane between the negative electrolyte and the positive electrolyte, in which at least two electrochemically active elements exist in the negative electrolyte, the positive electrolyte, or both.

21 CFR 172.856 - Propylene glycol mono- and diesters of fats and fatty acids.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Propylene glycol mono- and diesters of fats and... CONSUMPTION Multipurpose Additives § 172.856 Propylene glycol mono- and diesters of fats and fatty acids. Propylene glycol mono- and diesters of fats and fatty acids may be safely used in food, subject to the...

Molecularly uniform poly(ethylene glycol) certified reference material

NASA Astrophysics Data System (ADS)

Takahashi, Kayori; Matsuyama, Shigetomo; Kinugasa, Shinichi; Ehara, Kensei; Sakurai, Hiromu; Horikawa, Yoshiteru; Kitazawa, Hideaki; Bounoshita, Masao

2015-02-01

A certified reference material (CRM) for poly(ethylene glycol) with no distribution in the degree of polymerization was developed. The degree of polymerization of the CRM was accurately determined to be 23. Supercritical fluid chromatography (SFC) was used to separate the molecularly uniform polymer from a standard commercial sample with wide polydispersity in its degree of polymerization. Through the use of a specific fractionation system coupled with SFC, we are able to obtain samples of poly(ethylene glycol) oligomer with exact degrees of polymerization, as required for a CRM produced by the National Metrology Institute of Japan.

Redox pathways of the mitochondrion.

PubMed

Koehler, Carla M; Beverly, Kristen N; Leverich, Edward P

2006-01-01

The mitochondrion houses a variety of redox pathways, utilized for protection from oxidative damage and assembly of the organelle. The glutathione/glutaredoxin and thioredoxin systems function in the mitochondrial matrix. The intermembrane space is protected from oxidative damage via superoxide dismutase and glutathione. Subunits in the cytochrome bc (1) complex utilize disulfide bonds for enzymatic activity, whereas cytochrome oxidase relies on disulfide linkages for copper acquisition. A redox pathway (Mia40p and Erv1p) mediates the import of intermembrane space proteins such as the small Tim proteins, Cox17p, and Cox19p, which have disulfide bonds. Many of the candidate proteins with disulfide bridges possess a twin CX3C motif or CX9C motif and utilize both metal binding and disulfide linkages for function. It may seem surprising that the intermembrane space has developed redox pathways, considering that the buffered environment should be reducing like the cytosol. However, the prokaryotic origin of the mitochondrion suggests that the intermembrane space may be akin to the oxidative environment of the bacterial periplasm. Although the players forming disulfide bonds are not conserved between mitochondria and prokaryotes, the mitochondrion may have maintained redox chemistry as an assembly mechanism in the intermembrane space for the import of proteins and metals and enzymatic activity.

Tumor pHe-triggered charge-reversal and redox-responsive nanoparticles for docetaxel delivery in hepatocellular carcinoma treatment

NASA Astrophysics Data System (ADS)

Chen, Fengqian; Zhang, Jinming; Wang, Lu; Wang, Yitao; Chen, Meiwan

2015-09-01

The insufficient cellular uptake of nanocarriers and their slow drug release have become major obstacles for achieving satisfactory anticancer outcomes in nano-medicine therapy. Because of the slightly acidic extracellular environment (pHe ~ 6.5) and a higher glutathione (GSH) concentration (approximately 10 mM) in tumor tissue/cells, we firstly designed a novel d-α-tocopheryl polyethylene glycol 1000-poly(β-amino ester) block copolymer containing disulfide linkages (TPSS). TPSS nanoparticles (NPs) with pH- and redox-sensitive behaviors were developed for on-demand delivery of docetaxel (DTX) in hepatocellular carcinoma. DTX/TPSS NPs exhibited sensitive surface charge reversal from -47.6 +/- 2.5 mV to +22.5 +/- 3.2 mV when the pH decreased from 7.4 to 6.5, to simulate the pHe. Meanwhile, anabatic drug release of DTX/TPSS NPs was observed in PBS buffer (pH 6.5, 10 mM GSH). Due to the synergism between the pHe-triggered charge reversal and the redox-triggered drug release, enhanced drug uptake and anticancer efficacy were observed in HepG2 and SMMC 7721 cells treated with DTX/TPSS NPs. The positively charged NPs exhibited a stronger inhibitory effect on cell proliferation, promoted cell cycle arrest in the G2/M phase, and increased the rate of apoptosis. More importantly, based on the higher tumor accumulation of TPSS vehicles in vivo, a significant suppression of tumor growth, but without side-effects, was observed when DTX/TPSS NPs were injected intravenously into HepG2 xenograft tumor-bearing mice. Collectively, these results demonstrate that the newly developed dual-functional TPSS copolymer may be utilized as a drug delivery system for anticancer therapy.The insufficient cellular uptake of nanocarriers and their slow drug release have become major obstacles for achieving satisfactory anticancer outcomes in nano-medicine therapy. Because of the slightly acidic extracellular environment (pHe ~ 6.5) and a higher glutathione (GSH) concentration (approximately 10 m

Glutathione and redox signaling in substance abuse.

PubMed

Uys, Joachim D; Mulholland, Patrick J; Townsend, Danyelle M

2014-07-01

Throughout the last couple decades, the cause and consequences of substance abuse has expanded to identify the underlying neurobiological signaling mechanisms associated with addictive behavior. Chronic use of drugs, such as cocaine, methamphetamine and alcohol leads to the formation of oxidative or nitrosative stress (ROS/RNS) and changes in glutathione and redox homeostasis. Of importance, redox-sensitive post-translational modifications on cysteine residues, such as S-glutathionylation and S-nitrosylation could impact on the structure and function of addiction related signaling proteins. In this commentary, we evaluate the role of glutathione and redox signaling in cocaine-, methamphetamine- and alcohol addiction and conclude by discussing the possibility of targeting redox pathways for the therapeutic intervention of these substance abuse disorders. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Electron-beam-initiated polymerization of poly(ethylene glycol)-based wood impregnants.

PubMed

Trey, Stacy M; Netrval, Julia; Berglund, Lars; Johansson, Mats

2010-11-01

The current study demonstrates that methacrylate and acrylate poly(ethylene glycol) (PEG) functional oligomers can be effectively impregnated into wood blocks, and cured efficiently to high conversions without catalyst by e-beam radiation, allowing for less susceptibility to leaching, and favorable properties including higher Brinell hardness values. PEG based monomers were chosen because there is a long history of this water-soluble monomer being able to penetrate the cell wall, thus bulking it and decreasing the uptake of water which further protects the wood from fungal attack. Diacrylate, dimethacrylate, and dihydroxyl functional PEG of M(w) 550-575, of concentrations 0, 30, 60, and 100 wt % in water, were vacuum pressure impregnated into Scots Pine blocks of 15 × 25 × 50 mm in an effort to bulk the cell wall. The samples were then irradiated and compared with nonirradiated samples. It was shown by IR, DSC that the acrylate polymers were fully cured to much higher conversions than can be reached with conventional methods. Leaching studies indicated a much lower amount of oligomer loss from the cured vinyl functional PEG chains in comparison to hydroxyl functional PEG indicating a high degree of fastening of the polymer in the wood. The Brinell hardness indicated a significant increase in hardness to hardwood levels in the modified samples compared to the samples of hydroxyl functional PEG and uncured vinyl PEG samples, which actually became softer than the untreated Scots Pine. By monitoring the dimensions of the sample it was found by weight percent gain calculations (WPG %) that water helps to swell the wood structure and allow better access of the oligomers into the cell wall. Further, the cure shrinkage of the wood samples demonstrated infiltration of the oligomers into the cell wall as this was not observed for methyl methacrylate which is well-documented to remain in the lumen. However, dimensional stability of the vinyl polymer modified blocks when

Gold nanoparticles and polyethylene glycols functionalized conducting polyaniline nanowires for ultrasensitive and low fouling immunosensing of alpha-fetoprotein.

PubMed

Hui, Ni; Sun, Xiaotian; Song, Zhiling; Niu, Shuyan; Luo, Xiliang

2016-12-15

An ultrasensitive biosensor for alpha-fetoprotein was developed based on electrochemically synthesized polyaniline (PANI) nanowires, which were functionalized with gold nanoparticles (AuNPs) and polyethylene glycols (PEG). The prepared PEG/AuNPs/PANI composite, combining the electrical conductivity of the AuNPs/PANI with the robust antifouling ability of PEG, offered an ideal substrate for the development of low fouling electrochemical biosensors. Alpha-fetoprotein (AFP), a well-known hepatocellular carcinoma biomarker, was used as a model analyte, and its antibody was immobilized on the PEG/AuNPs/PANI for the construction of the AFP immunosensor. Using the redox current of PANI as the sensing signal, in addition to the good biocompatibility of PEG/AuNPs and the anti-biofouling property of PEG, the developed immunosensor showed improved biosensing performances, such as wide linear range and ultralow detection limit (0.007pgmL(-1)). More importantly, it is label-free, reagentless and low fouling, making it capable of assaying AFP in real serum samples without suffering from significant interference or biofouling. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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

2015-07-01

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

Influence of nanoparticle concentration on thermo-physical properties of CuO-propylene glycol nanofluids.

PubMed

Suganthi, Kuppusamy Swaminathan; Radhakrishnan, Anju K; Anusha, Natarajan; Rajan, Kalpoondi Sekar

2014-06-01

Experiments were performed on the preparation and characterization of CuO-propylene glycol nanofluids. The influence of nanoparticle concentration and temperature on nanofluid viscosity reveals existence of a range of nanoparticle concentration and temperature in which the viscosity of nanofluid is lower than that of propylene glycol, possibly due to interactions between nanoparticles and propylene glycol. A temperature-independent, thermal conductivity enhancement of 38% was obtained for nanoparticle concentration of 1.5 vol% over a temperature range of 10-60 degrees C. We believe that particle clustering contributes to the thermal conductivity enhancement in CuO-propylene glycol nanofluids.

Effect of redox potential and pH on TNT transformation in soil-water slurries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Price, C.B.; Brannon, J.M.; Hayes, C.A.

1997-10-01

The presence of 2,4,6-trinitrotoluene (TNT) and its transformation products in surface soil, the vadose zone, and ground water can present serious environmental problems. This situation is exacerbated because the processes that control the mobility and transformation of TNT are not well understood. The objective of this study was to determine the effects of redox potential (Eh) and pH on the fate and transformation of TNT in soil. An initial investigation of soil components responsible for the observed TNT transformation was also conducted. Laboratory investigations consisted of testing at four separate redox potentials and four pH levels. An 18:1 (water:soil) suspensionmore » spiked with 100 {micro}g/g TNT was used. Results indicated that TNT was unstable under all redox and pH conditions, and was least stable under highly reducing conditions at all four pH values. Greater amounts of TNT were incorporated into soil organic matter under anaerobic than under aerobic conditions. Results of the soil component study indicated that the presence of Fe{sup +2} sorbed to clay surfaces may account for the rapid disappearance of TNT at reduced redox potentials. TNT in ground water moving into areas of intense reduction would not persist for long, but would undergo transformation and binding by soil organic matter.« less

Surface Mechanical and Rheological Behaviors of Biocompatible Poly((D,L-lactic acid-ran-glycolic acid)-block-ethylene glycol) (PLGA-PEG) and Poly((D,L-lactic acid-ran-glycolic acid-ran-ε-caprolactone)-block-ethylene glycol) (PLGACL-PEG) Block Copolymers at the Air-Water Interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hyun Chang; Lee, Hoyoung; Khetan, Jawahar

Air–water interfacial monolayers of poly((d,l-lactic acid-ran-glycolic acid)-block-ethylene glycol) (PLGA–PEG) exhibit an exponential increase in surface pressure under high monolayer compression. In order to understand the molecular origin of this behavior, a combined experimental and theoretical investigation (including surface pressure–area isotherm, X-ray reflectivity (XR) and interfacial rheological measurements, and a self-consistent field (SCF) theoretical analysis) was performed on air–water monolayers formed by a PLGA–PEG diblock copolymer and also by a nonglassy analogue of this diblock copolymer, poly((d,l-lactic acid-ran-glycolic acid-ran-caprolactone)-block-ethylene glycol) (PLGACL–PEG). The combined results of this study show that the two mechanisms, i.e., the glass transition of the collapsed PLGA filmmore » and the lateral repulsion of the PEG brush chains that occur simultaneously under lateral compression of the monolayer, are both responsible for the observed PLGA–PEG isotherm behavior. Upon cessation of compression, the high surface pressure of the PLGA–PEG monolayer typically relaxes over time with a stretched exponential decay, suggesting that in this diblock copolymer situation, the hydrophobic domain formed by the PLGA blocks undergoes glass transition in the high lateral compression state, analogously to the PLGA homopolymer monolayer. In the high PEG grafting density regime, the contribution of the PEG brush chains to the high monolayer surface pressure is significantly lower than what is predicted by the SCF model because of the many-body attraction among PEG segments (referred to in the literature as the “n-cluster” effects). The end-grafted PEG chains were found to be protein resistant even under the influence of the “n-cluster” effects.« less

Ethylene Glycol - Polyethylene Glycol (EG-PEG) Mixtures: Infrared Spectra Wavelet Cross-Correlation Analysis.

PubMed

Caccamo, Maria Teresa; Magazù, Salvatore

2017-03-01