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https://www.readbyqxmd.com/read/28095321/cellulose-to-depolymerize%C3%A2-or-not-to
#1
REVIEW
Sergiu Coseri
Oxidation of the primary OH groups in cellulose is a pivotal reaction both at lab and industrial scale, leading to the value-added products, i.e. oxidized cellulose which have tremendous applications in medicine, pharmacy and hi-tech industry. Moreover, the introduction of carboxyl moieties creates prerequisites for further cellulose functionalization through covalent attachment or electrostatic interactions, being an essential achievement designed to boost the area of cellulose-based nanomaterials fabrication...
January 14, 2017: Biotechnology Advances
https://www.readbyqxmd.com/read/28069660/antioxidant-treatment-attenuates-lactate-production-in-diabetic-nephropathy
#2
Christoffer Laustsen, Per Mose Nielsen, Thomas Stokholm Nørlinger, Haiyun Qi, Uffe Kjærgaard Pedersen, Lotte Bonde Bertelsen, Jakob Appel Østergaard, Allan Flyvbjerg, Jan Henrik Ardenkjær-Larsen, Fredrik Palm, Hans Stødkilde-Jørgensen
The early progression of diabetic nephropathy is notoriously difficult to detect and quantify before the occurrence of substantial histological damage. Recently, hyperpolarized [1-(13)C]pyruvate has demonstrated increased lactate production in the kidney early after the onset of diabetes, implying increased lactate dehydrogenase activity as a consequence of increased nicotinamide adenine dinucleotide substrate availability due to upregulation of the polyol pathway, i.e., pseudohypoxia. In this study, we investigated the role of oxidative stress in mediating these metabolic alterations using state-of-the-art hyperpolarized magnetic resonance (MR) imaging...
January 1, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28064177/nitric-oxide-acts-upstream-of-ethylene-in-cell-wall-phosphorus-reutilization-in-phosphorus-deficient-rice
#3
Xiao Fang Zhu, Chun Quan Zhu, Chao Wang, Xiao Ying Dong, Ren Fang Shen
Nitric oxide (NO) and ethylene are both involved in cell wall phosphorus (P) reutilization in P-deficient rice; however, the crosstalk between them remains unclear. In the present study using P-deficient 'Nipponbare' (Nip), root NO accumulation significantly increased after 1 h and reached a maximum at 3 h, while ethylene production significantly increased after 3 h and reached a maximum at 6 h, indicating NO responded more quickly than ethylene. Irrespective of P status, addition of the NO donor sodium nitroprusside (SNP) significantly increased while the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) significantly decreased the production of ethylene, while neither the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) nor the ethylene inhibitor aminoethoxyvinylglycine (AVG) had any influence on NO accumulation, suggesting NO acted upstream of ethylene...
January 7, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28063096/feasibility-of-in-vivo-three-dimensional-t-2-mapping-using-dicarboxy-proxyl-and-cw-epr-based-single-point-imaging
#4
Harue Kubota, Denis A Komarov, Hironobu Yasui, Shingo Matsumoto, Osamu Inanami, Igor A Kirilyuk, Valery V Khramtsov, Hiroshi Hirata
OBJECTIVES: The aim of this study was to demonstrate the feasibility of in vivo three-dimensional (3D) relaxation time T 2(*) mapping of a dicarboxy-PROXYL radical using continuous-wave electron paramagnetic resonance (CW-EPR) imaging. MATERIALS AND METHODS: Isotopically substituted dicarboxy-PROXYL radicals, 3,4-dicarboxy-2,2,5,5-tetra((2)H3)methylpyrrolidin-(3,4-(2)H2)-(1-(15)N)-1-oxyl ((2)H,(15)N-DCP) and 3,4-dicarboxy-2,2,5,5-tetra((2)H3)methylpyrrolidin-(3,4-(2)H2)-1-oxyl ((2)H-DCP), were used in the study...
January 6, 2017: Magma
https://www.readbyqxmd.com/read/28062279/nitric-oxide-induced-synthesis-of-hydrogen-sulfide-alleviates-osmotic-stress-in-wheat-seedlings-through-sustaining-antioxidant-enzymes-osmolyte-accumulation-and-cysteine-homeostasis
#5
M Nasir Khan, M Mobin, Zahid Khorshid Abbas, Manzer H Siddiqui
Nitric oxide (NO) and hydrogen sulfide (H2S) have been shown to act as signaling molecules in various physiological processes, play significant roles in plant cellular processes, and also mediate responses to both biotic and abiotic stresses in plants. The present investigation was carried out to test the effect of exogenous NO on endogenous synthesis of H2S in osmotic-stressed wheat (Triticum aestivum L.) seedlings. The results show that application of NO to wheat seedlings, suffered from PEG8000-induced osmotic stress, considerably enhanced the activities of H2S-synthesizing enzymes l-cysteine desulfhydrase (LCD) and d-cysteine desulfhydrase (DCD) leading to enhanced level of endogenous H2S content...
January 3, 2017: Nitric Oxide: Biology and Chemistry
https://www.readbyqxmd.com/read/28052402/electron-spin-resonance-studies-on-deuterated-nitroxyl-spin-probes-used-in-overhauser-enhanced-magnetic-resonance-imaging
#6
D David Jebaraj, Hideo Utsumi, A Milton Franklin Benial
The Electron Spin Resonance studies were carried out for 2 mM concentration of (14) N and (15) N -labeled 3-carbamoyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl, 3-carboxy-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl, 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl and their deuterated nitroxyl radicals using X-band Electron Spin Resonance spectrometer. The ESR Line shape analysis was carried out. The Electron Spin Resonance parameters such as, linewidth, Lorentzian component, signal intensity ratio, rotational correlation time, hyperfine coupling constant and g-factor were estimated...
January 4, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28042034/the-nitroxide-tempo-inhibits-hydroxyl-radical-production-from-the-fenton-like-reaction-of-iron-ii-citrate-with-hydrogen-peroxide
#7
Fengqiang Shi, Peifeng Zhang, Yujia Mao, Can Wang, Meiqing Zheng, Zhongwei Zhao
In vivo physiological ligand citrate can bind iron(II) ions to form the iron(II)-citrate complex. Inhibition of hydroxyl radical (OH) production from the Fenton-like reaction of iron(II)-citrate with H2O2 is biologically important, as this reaction may account for one of the mechanisms of the labile iron pool in vivo to induce oxidative stress and pathological conditions. Nitroxides have promising potentials as therapeutic antioxidants. However, there are controversial findings indicating that they not only act as antioxidants but also as pro-oxidants when engaged in Fenton reactions...
December 29, 2016: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28036163/immunosensors-for-c-reactive-protein-based-on-ultrathin-films-of-carboxylated-cellulose-nanofibrils
#8
Yanxia Zhang, Orlando J Rojas
C-reactive protein (CRP) is an acute phase protein that has been widely used as a predictor of cardiovascular diseases. We report herein the synthesis of immunosensors based on carboxylated cellulose nanofibrils (CNF) for CRP detection, as demonstrated by quartz crystal microgravimetry (QCM). QCM sensors carrying ultrathin films of carboxylated CNF were prepared by using two protocols: (i) spin coating of CNF on the sensors followed by carboxylation via in situ oxidation with 2,2,6,6-tetramethylpiperidine 1-oxyl and (ii) carboxymethylation of CNF in aqueous dispersion followed by spin coating deposition on the sensors...
January 18, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28032021/detection-of-ligand-induced-conformational-changes-in-the-activation-loop-of-aurora-a-kinase-by-peldor-spectroscopy
#9
Selena G Burgess, Maria Grazia Concilio, Richard Bayliss, Alistair J Fielding
The structure of protein kinases has been extensively studied by protein crystallography. Conformational movement of the kinase activation loop is thought to be crucial for regulation of activity; however, in many cases the position of the activation loop in solution is unknown. Protein kinases are an important class of therapeutic target and kinase inhibitors are classified by their effect on the activation loop. Here, we report the use of pulsed electron double resonance (PELDOR) and site-directed spin labeling to monitor conformational changes through the insertion of MTSL [S-(1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1 H-pyrrol-3-yl)methyl methanesulfonothioate] on the dynamic activation loop and a stable site on the outer surface of the enzyme...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28012884/erythrocytes-properties-in-varicose-veins-patients
#10
L Gwozdzinski, A Pieniazek, J Bernasinska, M Grabowski, E Kowalczyk, K Gwozdzinski
Varicose veins (VV) are enlarged veins of the subcutaneous tissue, usually caused by faulty or damaged venous valves leading to impaired blood flow. Blood stasis, excessive clotting disorder and alterations in the vein walls are symptoms of Virchow's triad which may affect the morphotic elements of blood, including erythrocytes. The aim of this study was to investigate alterations in the properties of the erythrocytes taken from varicose veins in comparison to those from antecubital vein of patients with chronic venous disease...
December 21, 2016: Microvascular Research
https://www.readbyqxmd.com/read/28006433/intracerebroventricular-tempol-administration-in-older-rats-reduces-oxidative-stress-in-the-hypothalamus-but-does-not-change-stat3-signalling-or-sirt1-ampk-pathway
#11
Hale Z Toklu, Philip J Scarpace, Yasemin Sakarya, Nataliya Kirichenko, Michael Matheny, Erin B Bruce, Christy S Carter, Drake Morgan, Nihal Tümer
Hypothalamic inflammation and increased oxidative stress are believed to be mechanisms that contribute to obesity. 4-Hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (tempol), a free radical scavenger, has been shown to reduce inflammation and oxidative stress. We hypothesized that brain infusion of tempol would reduce oxidative stress, and thus would reduce food intake and body weight and improve body composition in rats with age-related obesity and known elevated oxidative stress. Furthermore, we predicted an associated increase in markers of leptin signalling, including the silent mating type information regulator 2 homolog 1 (SIRT1)/5'AMP-activated protein kinase (AMPK) pathway and the signal transducer and activator of transcription 3 (STAT3) pathway...
January 2017: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
https://www.readbyqxmd.com/read/27997159/the-formation-time-of-ti-o-%C3%A2-and-ti-o-%C3%A2-ti-radicals-at-the-n-srtio3-aqueous-interface-during-photocatalytic-water-oxidation
#12
Xihan Chen, Stephanie N Choing, Daniel J Aschaffenburg, C D Pemmaraju, David Prendergast, Tanja Cuk
The initial step of photocatalytic water oxidation reaction at the metal oxide/aqueous interface involves intermediates formed by trapping photogenerated, valence band holes on different reactive sites of the oxide surface. In SrTiO3, these one-electron intermediates are radicals located in Ti-O(•) (oxyl) and Ti-O(•)-Ti (bridge) groups arranged perpendicular and parallel to the surface respectively, and form electronic states in the band gap of SrTiO3. Using an ultrafast sub band gap probe of 400 nm and white light, we excited transitions between these radical states and the conduction band...
December 20, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27995786/cellulose-nanofibers-prepared-using-the-tempo-laccase-o2-system
#13
Jie Jiang, Wenbo Ye, Liang Liu, Zhiguo Wang, Yimin Fan, Tsuguyuki Saito, Akira Isogai
The 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)/laccase/O2 system was used to prepare cellulose nanofibers from wood cellulose without requiring any chlorine-containing oxidant. Laccase was degraded by oxidized TEMPO (TEMPO(+)) formed by laccase-mediated oxidation with O2, which competed with the oxidation of wood cellulose. Thus, large amounts of laccase and TEMPO and a long reaction time were needed to introduce ∼0.6 mmol g(-1) of C6-carboxylate groups onto wood cellulose. The TEMPO/laccase/O2 system underwent one-way reaction from TEMPO to reduced TEMPO through TEMPO(+)...
December 20, 2016: Biomacromolecules
https://www.readbyqxmd.com/read/27980017/nitric-oxide-modulates-histone-acetylation-at-stress-genes-by-inhibition-of-histone-deacetylases
#14
Alexander Mengel, Alexandra Ageeva, Elisabeth Georgii, Jörg Bernhardt, Keqiang Wu, Jörg Durner, Christian Lindermayr
Histone acetylation, which is an important mechanism to regulate gene expression, is controlled by the opposing action of histone acetyltransferases (HATs) and histone deacetylases (HDACs). In animals, several HDACs are subjected to regulation by nitric oxide (NO), in plants however, it is unknown whether NO affects histone acetylation. We found that treatment with the physiological NO-donor S-nitroso-glutathione (GSNO) increased the abundance of several histone acetylation marks in Arabidopsis, which was strongly diminished in the presence of the NO scavenger 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO)...
December 15, 2016: Plant Physiology
https://www.readbyqxmd.com/read/27973871/unveiling-the-reactivity-of-a-synthetic-mimic-of-the-oxygen-evolving-complex
#15
Umberto Raucci, Ilaria Ciofini, Carlo Adamo, Nadia Rega
We simulated for the first time the oxygen-oxygen bond formation in a synthetic calcium-tetra manganese complex recently developed by Zhang and co-workers. In spite of promising structural similarities to the native oxygen evolving complex (OEC) in Photosystem II, several uncertainties on the mimic stability in water and on its potential catalytic activity still persist. Here, we characterized at density functional theory level the electronic and structural features of the Sn states of the complex, along with the oxygen-oxygen bond formation reaction, proposing a reasonable model for the hydrate complex...
December 15, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27936660/room-temperature-magnetic-switchability-assisted-by-hysteretic-valence-tautomerism-in-a-layered-two-dimensional-manganese-radical-coordination-framework
#16
Anthony Lannes, Yan Suffren, Jean Bernard Tommasino, Rodica Chiriac, François Toche, Lhoussain Khrouz, Florian Molton, Carole Duboc, Isabelle Kieffer, Jean-Louis Hazemann, Christian Reber, Andreas Hauser, Dominique Luneau
The manganese-nitronyl-nitroxide two-dimensional coordination polymer {[Mn2(NITIm)3]ClO4}n (1) (NITImH = 2-(2-imidazolyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-3-oxide-1-oxyl) undergoes an unusual hysteretic thermo-induced valence tautomeric transition near room temperature, during which the manganese(II) ions are oxidized to manganese(III) and two of the three deprotonated radicals (NITIm(-)) are reduced to their diamagnetic aminoxyl form (denoted NITRed(2-)). Upon cooling, the high-temperature species {[Mn(II)2(NITIm)3]ClO4}n (1HT) turns into the low-temperature species {[Mn(III)2(NITRed)2(NITIm)]ClO4}n (1LT) around 274 K, while on heating the process is reversed at about 287 K...
December 21, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27935073/no-accumulation-alleviates-h2-o2-dependent-oxidative-damage-induced-by-ca-no3-2-stress-in-the-leaves-of-pumpkin-grafted-cucumber-seedlings
#17
Lin Li, Sheng Shu, Qing Xu, Ya-Hong An, Jin Sun, Shi-Rong Guo
Nitric oxide (NO) and hydrogen peroxide (H2 O2 ), two important signalling molecules, are stimulated in plants by abiotic stresses. In this study, we investigated the role of NO and its interplay with H2 O2 in the response of self-grafted and salt-tolerant pumpkin-grafted (Cucurbita maxima × C. moschata) cucumber seedlings to 80 mM Ca(NO3 )2 stress. Endogenous NO and H2 O2 production in self-grafted seedlings increased in a time-dependent manner, reaching maximum levels after 24 h of Ca(NO3 )2 stress. In contrast, a transient increase in NO production, accompanied by H2 O2 accumulation, was observed at 2 h in rootstock-grafted plants...
December 9, 2016: Physiologia Plantarum
https://www.readbyqxmd.com/read/27934460/kinetic-study-of-the-reaction-of-the-phthalimide-n-oxyl-radical-with-amides-structural-and-medium-effects-on-the-hydrogen-atom-transfer-reactivity-and-selectivity
#18
Massimo Bietti, Veronica Forcina, Osvaldo Lanzalunga, Andrea Lapi, Teo Martin, Marco Mazzonna, Michela Salamone
A kinetic study of the hydrogen atom transfer (HAT) reactions from a series of secondary N-(4-X-benzyl)acetamides and tertiary amides to the phthalimide-N-oxyl radical (PINO) has been carried out. The results indicate that HAT is strongly influenced by structural and medium effects; in particular, the addition of Brønsted and Lewis acids determines a significant deactivation of C-H bonds α to the amide nitrogen of these substrates. Thus, by changing the reaction medium, it is possible to carefully control the regioselectivity of the aerobic oxidation of amides catalyzed by N-hydroxyphthalimide, widening the synthetic versatility of this process...
December 2, 2016: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/27926840/calcium-dependent-structural-dynamics-of-a-spin-labeled-ryr-peptide-bound-to-calmodulin
#19
Cheng Her, Jesse E McCaffrey, David D Thomas, Christine B Karim
We have used chemical synthesis, electron paramagnetic resonance (EPR), and circular dichroism to detect and analyze the structural dynamics of a ryanodine receptor (RyR) peptide bound to calmodulin (CaM). The skeletal muscle calcium release channel RyR1 is activated by Ca(2+)-free CaM and inhibited by Ca(2+)-bound CaM. To probe the structural mechanism for this regulation, wild-type RyRp and four spin-labeled derivatives were synthesized, each containing the nitroxide probe 2,2,6,6-tetramethyl-piperidine-1-oxyl-4-amino-4-carboxylic acid substituted for a single amino acid...
December 6, 2016: Biophysical Journal
https://www.readbyqxmd.com/read/27910780/naringenin-ameliorates-doxorubicin-toxicity-and-hypoxic-condition-in-dalton-s-lymphoma-ascites-tumor-mouse-model-evidence-from-electron-paramagnetic-resonance-imaging
#20
Venkatesan Kathiresan, Swathika Subburaman, Arun Venkatesh Krishna, Mathivanan Natarajan, Gandhidasan Rathinasamy, Kumaresan Ganesan, Murugesan Ramachandran
Doxorubicin (DOX) is a well-known cytotoxic agent used extensively as a chemotherapeutic drug to eradicate a wide variety of human cancers. Reactive oxygen species (ROS)-mediated oxidative stress during DOX treatment can induce cardiac, renal, and hepatic toxicities, which can constrain its use as a potential cytotoxic agent. The present work investigates the antioxidant potential of naringenin (NAR) against DOXinduced toxicities of a Dalton's lymphoma ascites (DLA) tumor-bearing mouse model. Mice were randomized into four groups: a negative control, positive control, DOX (2...
2016: Journal of Environmental Pathology, Toxicology and Oncology
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