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Oxygen kinetics

Takashi Ishida, Sachie Suzuki, Chen-Yi Lai, Satoshi Yamazaki, Shigeru Kakuta, Yoichiro Iwakura, Masanori Nojima, Yasuo Takeuchi, Masaaki Higashihara, Hiromitsu Nakauchi, Makoto Otsu
Hematopoietic stem cell (HSC) transplantation (HSCT) for malignancy requires toxic pre-conditioning to maximize anti-tumor effects and donor-HSC engraftment. While this induces bone marrow (BM)-localized inflammation, how this BM environmental change affects transplanted HSCs in vivo remains largely unknown. We here report that, depending on interval between irradiation and HSCT, residence within lethally irradiated recipient BM compromises donor-HSC reconstitution ability. Both in vivo and in vitro we demonstrate that, among inflammatory cytokines, TNF-α plays a role in HSC damage: TNF-α stimulation leads to accumulation of reactive oxygen species (ROS) in highly purified hematopoietic stem/progenitor cells (HSCs/HSPCs)...
October 18, 2016: Stem Cells
Joon-Ii Jun, Lester F Lau
The expression of Ccn2 (CTGF) has been linked to fibrosis in many tissues and pathologies, although its activities in fibroblastic cells and precise mechanism of action in fibrogenesis are still controversial. Here, we showed that CCN2 can induce cellular senescence in fibroblasts both in vitro and in vivo, whereupon senescent cells express an anti-fibrotic "senescence-associated secretory phenotype" (SASP) that includes upregulation of matrix metalloproteinases and downregulation of collagen. Mechanistically, CCN2 induces fibroblast senescence through integrin α6β1-mediated accumulation of reactive oxygen species, leading to activation of p53 and induction of p16(INK4a)...
October 18, 2016: Journal of Cell Communication and Signaling
Michael I Jacobs, Bo Xu, Oleg Kostko, Nadja Heine, Musahid Ahmed, Kevin R Wilson
The heterogeneous reaction of ozone (O3) with 200 nm squalene nanoparticles is studied using near edge X-ray absorption fine structure (NEXAFS), ultraviolet (UPS) and X-ray photoelectron spectroscopy (XPS). Photoelectrons are detected from free nanoparticle beams using a velocity map imaging (VMI) spectrometer capable of detecting photoelectrons with up to 40 eV of kinetic energy. Heterogeneous kinetics are quantified using changes in the UPS, XPS and NEXAFS spectrum, yielding uptake coefficients for the decay of the double bonds in squalene of (3...
October 17, 2016: Journal of Physical Chemistry. A
Jenny M Pedersen, Yoo-Sik Shim, Vaibhav Hans, Martin B Phillips, Jeffrey M Macdonald, Glenn Walker, Melvin E Andersen, Harvey J Clewell, Miyoung Yoon
Accurate prediction of metabolism is a significant outstanding challenge in toxicology. The best predictions are based on experimental data from in vitro systems using primary hepatocytes. The predictivity of the primary hepatocyte-based culture systems, however, is still limited due to well-known phenotypic instability and rapid decline of metabolic competence within a few hours. Dynamic flow bioreactors for three-dimensional cell cultures are thought to be better at recapitulating tissue microenvironments and show potential to improve in vivo extrapolations of chemical or drug toxicity based on in vitro test results...
2016: Frontiers in Bioengineering and Biotechnology
G Meenakshi, A Sivasamy
Semiconductor zinc oxide nanorods (NRZnO) were prepared by sol-gel technique using zinc acetate as the precursor and ammonia as the precipitating agent. The prepared photocatalyst were characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), UV-Visible diffuse reflectance spectroscopy (UV-Vis-DRS), X-ray photoelectron spectroscopy (XPS), Field Emission-Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM), High Resolution-Tunneling Microscope (HR-TEM), Brunauer, Emmett and Teller (BET) and electron paramagnetic resonance spectroscopy (EPR) analysis...
October 13, 2016: Ecotoxicology and Environmental Safety
Rogério Santos Cde Oliveira Cruz, Tiago Turnes, Rafael Alves de Aguiar, Fabrizio Caputo
The off-transient pulmonary oxygen uptake (V̇O2) response to a single bout of intense, exhaustive exercise has been characterized over the years by a second-order exponential model. In this paper, we report the superiority of a third-order exponential decay in describing the V̇O2 off-kinetics after a maximal cycling exercise lasting 60-s. Our findings are in accordance with a biphasic pattern of phosphocreatine resynthesis when muscle pH is affected.
October 12, 2016: Respiratory Physiology & Neurobiology
Junguo Li, Bao Liu, Yanan Zeng, Ziming Wang
AOD (argon oxygen decarburization) slag, which is the by-product of the stainless steel refining process, is a recyclable slag because of its high content of calcium and silicon. The leaching toxicity cannot be ignored in the recycling process because the slag contains a certain amount of Cr. In this study, the mineral analysis, batch leaching tests and thermodynamic and kinetic modeling by PHREEQC combined with FactSage software were performed to explore the influence of the dissolution of primary minerals and the precipitation of secondary minerals on the elution of Cr from AOD slag...
October 11, 2016: Chemosphere
Paolo Pirovano, Erik R Farquhar, Marcel Swart, Aidan Richard McDonald
Two metastable NiIII complexes, [NiIII(OAc)(L)] and [NiIII(ONO2)(L)] (L = N,N'-(2,6-dimethylphenyl)-2,6-pyridinedicarboxamidate, OAc = acetate), were prepared, adding to the previously prepared [NiIII(OCO2H)(L)], with the purpose of probing the properties of terminal late-transition metal oxidants. These high-valent oxidants were prepared by the one-electron oxidation of their NiII precursors ([NiII(OAc)(L)]- and [NiII(ONO2)(L)]-) with tris(4-bromophenyl)ammoniumyl hexachloroantimonate. Fascinatingly, the reaction between any [NiII(X)(L)]- and NaOCl/acetic acid (AcOH) or cerium ammonium nitrate ((NH4)2[CeIV(NO3)6], CAN), yielded [NiIII(OAc)(L)] and [NiIII(ONO2)(L)], respectively...
October 14, 2016: Journal of the American Chemical Society
Andrea von Zadow, Elisabeth Ignatz, Richard Pokorny, Lars-Oliver Essen, Gabriele Klug
Photolyases are efficient DNA repair enzymes that specifically repair either cyclobutane pyrimidine dimers (CPD) or (6-4) photoproducts in a light-dependent cleavage reaction. The closely related classical cryptochrome blue light photoreceptors do not repair DNA lesions, instead they are involved in regulatory processes. CryB of Rhodobacter sphaeroides was until now described as a cryptochrome that affects light-dependent and singlet oxygen-dependent gene expression and is unusual in terms of its cofactor composition...
October 14, 2016: FEBS Journal
Cleyton Martins da Silva, Luane Lima da Silva, Sergio Machado Corrêa, Graciela Arbilla
Volatile organic compounds (VOCs) play a central role in atmospheric chemistry. In this work, the kinetic and mechanistic reactivities of VOCs are analyzed, and the contribution of the organic compounds emitted by anthropogenic and natural sources is estimated. VOCs react with hydroxyl radicals and other photochemical oxidants, such as ozone and nitrate radicals, which cause the conversion of NO to NO2 in various potential reaction paths, including photolysis, to form oxygen atoms, which generate ozone. The kinetic reactivity was evaluated based on the reaction coefficients for hydroxyl radicals with VOCs...
October 13, 2016: Bulletin of Environmental Contamination and Toxicology
K Divakar, M Suryia Prabha, G Nandhinidevi, Pennathur Gautam
The simultaneous production of intracellular esterase and extracellular protease from the strain Lysinibacillus fusiformis AU01 was studied in detail. The production was carried out both under batch and fedbatch mode. The maximum yield of intracellular esterase and protease was obtained under full oxygen saturation at the beginning of the fermentation. The data was fitted to the Luedeking-Piret model and it was shown that the enzyme (both esterase and protease) production was growth-associated. A decrease in intracellular esterase and increase in the extracellular esterase was observed during late stationary phase...
October 13, 2016: Preparative Biochemistry & Biotechnology
Chenyi Yuan, Mrinal Chakraborty, Silvio Canonica, Linda Kay Weavers, Christopher M Hadad, Yu-Ping Chin
Isoproturon (IPU) is a phenylurea herbicide used to control broad-leaf grasses on grain fields. Photosensitized transformation induced by excited triplet states of dissolved organic matter (3DOM*) has been identified as an important degradation pathway for IPU in sunlit waters, but the reappearance of IPU in the absence of light is observed after the initial photolysis. In this study, we elucidate the kinetics of this photo-degradation and dark-reappearance cycling of IPU in the presence of DOM proxies (aromatic ketones and reference fulvic acids)...
October 14, 2016: Environmental Science & Technology
Fernando L Rosario-Ortiz, Silvio Canonica
The photochemical properties of dissolved organic matter (DOM) have been of interest to scientists and engineers since the 1970s. Upon light absorption, chromophoric DOM (CDOM) can sensitize the formation of different short-lived reactive intermediates (RIs), including hydroxyl radical ((•)OH), singlet oxygen ((1)O2) and superoxide radical anion (O2(-•)). In addition, a fraction of the excited singlet states in CDOM decays into excited triplet states ((3)CDOM*), which are also important photochemical transients in environmental systems...
October 13, 2016: Environmental Science & Technology
Chung-Wein Lee, Keith M Stantz
BACKGROUND: Tumor hypoxia is involved in every stage of solid tumor development: formation, progression, metastasis, and apoptosis. Two types of hypoxia exist in tumors-chronic hypoxia and acute hypoxia. Recent studies indicate that the regional hypoxia kinetics is closely linked to metastasis and therapeutic responses, but regional hypoxia kinetics is hard to measure. We propose a novel approach to determine the local pO2 by fusing the parameters obtained from in vivo functional imaging through the use of a modified multivariate Krogh model...
October 12, 2016: Biomedical Engineering Online
Xin Zhang, Chuan-Wang Yang, Han-Qing Yu, Guo-Ping Sheng
Microbial extracellular polymeric substances (EPS) widely exist in natural environments and affect the migration and transformation of pollutants in aquatic environments. Previous works report that EPS have some reducing functional groups and can reduce heavy metals. However, because of the weak reducing capability of EPS, the reduction of heavy metals by EPS without cells is extremely slow, and its effect on heavy metals species is insignificant. In this work, the accelerated reduction of silver ions (Ag(+)) by EPS from Shewanella oneidensis MR-1 under illumination was investigated...
October 5, 2016: Water Research
Fabian Cantu Reinhard, Mala Sainna, Pranav Upadhayay, Alex Balan, Devesh Kumar, Simonetta Fornarini, Maria Elisa Crestoni, Samuel de Visser
Cytochrome P450 enzymes are heme containing mono-oxygenases that mainly react through oxygen atom transfer. Specific features of substrate and oxidant that determine the reaction rate constant for oxygen atom transfer are still poorly understood and, therefore, we did a systematic gas-phase study on reactions by iron(IV)-oxo porphyrin cation radical structures with arenes. We present here the first results obtained by using Fourier transform-ion cyclotron resonance mass spectrometry and provide rate constants and product distributions for the assayed reactions...
October 11, 2016: Chemistry: a European Journal
Gaetano Speciale, Marco Farren-Dai, Fahimeh S Shidmoossavee, Spencer J Williams, Andrew J Bennet
The hydroxide-catalyzed hydrolysis of aryl 1,2-trans-glycosides proceeds through a mechanism involving neighboring group participation by a C2-oxyanion and rate-limiting formation of a 1,2-anhydro sugar (oxirane) intermediate. The transition state for the hydroxide catalyzed hydrolysis of 4-nitrophenyl α-D-mannopyranoside in aqueous media has been studied by the use of multiple kinetic isotope effect (KIE) measurements in conjunction with ab initio theoretical methods. The experimental KIEs are: C1-(2)H (1...
October 10, 2016: Journal of the American Chemical Society
Jan Clausmeyer, Alexander Botz, Denis Öhl, Wolfgang Schuhmann
Silver nanoclusters are deposited on bifunctional Θ-shaped nanoelectrodes consisting of a carbon nanoelectrode combined with a hollow nanopipette. The Θ-nanoelectrodes are used as model systems to study interfacial mass transport in gas diffusion electrodes and in particular oxygen-depolarized cathodes (ODC) for the oxygen reduction reaction (ORR) in chlor-alkali electrolysers. By local delivery of O2 gas to the electroactive Ag nanoclusters through the adjacent nanopipette, enhanced currents for the ORR at the Ag nanoparticles are recorded which are not accountable when considering the low solubility and slow diffusion of O2 in highly alkaline media...
September 15, 2016: Faraday Discussions
E Ventosa, T Löffler, F La Mantia, W Schuhmann
Memory effects in Li-ion battery materials have been explained on the basis of the thermodynamics of many-particles body, however the role of the (de-)intercalation kinetics is not yet clear. We demonstrate that kinetic aspects, specifically Li-ion mobility, are determining the magnitude of the memory effect in TiO2 by studying samples with different levels of oxygen vacancies.
September 20, 2016: Chemical Communications: Chem Comm
Carolina Gómez-Gaete, Macarena Retamal, Catalina Chávez, Paulina Bustos, Ricardo Godoy, Pablo Torres-Vergara
Rhein is an active metabolite of the drug diacerein, whose anti-inflammatory properties have been demonstrated in both in vitro and in vivo models. However, the low oral bioavailability of rhein has limited its utility as a potential treatment of osteoarthritis (OA), a chronic inflammatory disease. In order to overcome this limitation, the aim of this work was the development of a drug delivery system intended for intra-articular administration of rhein, based on polymeric biodegradable PLGA microparticles (MPs) loaded with the drug...
October 6, 2016: European Journal of Pharmaceutical Sciences
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