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https://www.readbyqxmd.com/read/29243929/the-chemistry-of-some-dalodesmidean-millipedes-from-tasmania-diplopoda-polydesmida
#1
Tappey H Jones, Dylan M Guthrie, Conor T Hogan, Donovan J Robinson, Robert Mesibov, William A Shear, Thomas F Spande, Ralph A Saporito
Millipedes (Diplopoda) are well known for their toxic or repellent defensive secretions. As part of a larger investigation, we describe the chemical constituents of 14 species of Tasmanian millipedes in seven genera. Six species in the genus Gasterogramma were found to produce acyclic ketones, including the pungent unsaturated ketones 1, 2, and 6, and the novel (rel-3R,5S,7S)-3,5,7-trimethyl-2,8-decanedione (7b), for which the stereoconfiguration was established by stereoselective syntheses of pairs of isomers...
December 15, 2017: Journal of Natural Products
https://www.readbyqxmd.com/read/29243680/a-review-of-peek-polymer-s-properties-and-its-use-in-prosthodontics
#2
Gediminas Skirbutis, Agnė Dzingutė, Viltė Masiliūnaitė, Gabrielė Šulcaitė, Juozas Žilinskas
OBJECTIVE: The aim of this study is to review polyether ether ketone (PEEK), its characteristics and use in prosthodontics. MATERIAL AND METHODS: Information search for articles about PEEK and it's use in prosthodontics between January 2010 and April 2017 was conducted in Medline via PubMed, Science direct, Wiley online library as well as the Web search Google Scholar sources. Twelve full text articles were selected and used in this review. RESULTS: 143 articles were found in the database using keywords: PEEK, prosthodontics, dentistry...
2017: Stomatologija
https://www.readbyqxmd.com/read/29243208/plasma-cholinesterase-activity-in-female-green-turtles-chelonia-mydas-nesting-in-laguna-de-terminos-mexico-related-to-organochlorine-pesticides-in-their-eggs
#3
Gerardo Rivas-Hernández, Yaneli May-Uc, Elsa Noreña-Barroso, Víctor Cobos-Gasca, Gabriela Rodríguez-Fuentes
The inhibition of cholinesterase (ChE) activity has been used as a biomarker of exposure to organophosphate and carbamate insecticides. ChE of nesting female green turtles (Chelonia mydas) were biochemically characterized using two substrates, acetylthiocholine iodide and butyrylthiocholine iodide, and three ChE inhibitors (eserine sulfate, BW284C51 and iso-OMPA). The results indicated that BChE is the predominant plasma ChE in female C. mydas, but with atypical properties that differ from those found in human BChE...
December 14, 2017: Bulletin of Environmental Contamination and Toxicology
https://www.readbyqxmd.com/read/29242865/a-nickel-catalyzed-acceptorless-dehydrogenative-approach-to-quinolines
#4
Seuli Parua, Rina Sikari, Suman Sinha, Siuli Das, Gargi Chakraborty, Nanda D Paul
A general, efficient and environmentally benign, one-step synthesis of substituted quinoline derivatives was achieved by acceptorless dehydrogenative coupling of o-aminobenzylalcohols with ketones and secondary alcohols catalyzed by a cheap, earth abundant and easy to prepare nickel catalyst [Ni(MeTAA)], featuring a tetraaza macrocyclic ligand (tetramethyltetraaza[14]annulene (MeTAA)). A wide variety of substituted quinolines were synthesized in high yields starting from readily available o-aminobenzylalcohols and ketones or secondary alcohols...
December 15, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/29242353/cardiac-specific-bdh1-overexpression-ameliorates-oxidative-stress-and-cardiac-remodeling-in-pressure-overload-induced-heart-failure
#5
Motoki Uchihashi, Atsushi Hoshino, Yoshifumi Okawa, Makoto Ariyoshi, Satoshi Kaimoto, Shuhei Tateishi, Kazunori Ono, Ryoetsu Yamanaka, Daichi Hato, Yohei Fushimura, Sakiko Honda, Kuniyoshi Fukai, Yusuke Higuchi, Takehiro Ogata, Eri Iwai-Kanai, Satoaki Matoba
BACKGROUND: Energy starvation and the shift of energy substrate from fatty acids to glucose is the hallmark of metabolic remodeling during heart failure progression. However, ketone body metabolism in the failing heart has not been fully investigated. METHODS AND RESULTS: Microarray data analysis and mitochondrial isobaric tags for relative and absolute quantification proteomics revealed that the expression of D-β-hydroxybutyrate dehydrogenase I (Bdh1), an enzyme that catalyzes the NAD+/NADH coupled interconversion of acetoacetate and β-hydroxybutyrate, was increased 2...
December 2017: Circulation. Heart Failure
https://www.readbyqxmd.com/read/29241990/influence-of-metformin-and-insulin-on-myocardial-substrate-oxidation-under-conditions-encountered-during-cardiac-surgery
#6
Cyonna Holmes, LaShondra Powell, Nicholas S Clarke, Michael E Jessen, Matthias Peltz
BACKGROUND: The influence of diabetic therapies on myocardial substrate selection during cardiac surgery is unknown but may be important to ensure optimal surgical outcomes. We hypothesized that metformin and insulin alter myocardial substrate selection during cardiac surgery and may affect reperfusion cardiac function. METHODS: Rat hearts (n = 8 per group) were evaluated under 3 metabolic conditions: normokalemia, cardioplegia, or bypass. Groups were perfused with Krebs-Henseleit buffer in the presence of no additives, metformin, insulin, or both insulin and metformin...
December 11, 2017: Surgery
https://www.readbyqxmd.com/read/29241011/silver-free-palladium-catalyzed-c-sp3-h-arylation-of-saturated-bicyclic-amine-scaffolds
#7
Charlotte E Coomber, Laure Benhamou, Dejan-Krešimir Bučar, Peter D Smith, Michael J Porter, Tom David Sheppard
Herein we report a silver-free Pd(II)-catalyzed C(sp3)-H arylation of saturated bicyclic and tricyclic amine scaffolds. The reaction provides good yields using a range of aryl iodides and aryl bromides including functionalized examples bearing aldehydes, ketones, esters, free phenols and heterocycles. The methodology has been applied to medicinally relevant scaffolds. Two of the intermediate palladium complexes in the catalytic cycle have been prepared and characterized, and a mechanism proposed. Removal of the directing group proceeded with good yield under relatively mild conditions...
December 14, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29240444/regio-and-diastereodivergent-4-2-cycloadditions-with-cyclic-2-4-dienones
#8
Wei Xiao, Qian-Qian Yang, Zhi Chen, Qin Ouyang, Wei Du, Ying-Chun Chen
By employing activated alkenes with bulky α-functional groups, such as α-cyano-α,β-unsaturated ketones and Meldrum's acid-based alkenes, a previously unreported cross-trienamine pathway of cyclic 2,4-dienones is adopted to deliver γ',δ-regioselective [4 + 2] cycloadducts catalyzed by cinchona-derived amines. In addition, a diastereodivergent [4 + 2] cycloaddition reaction is realized with Z-configured 4-alkylideneisoxazol-5(4H)-ones under similar catalytic conditions, even through a three- or four-component cascade process with simple starting materials...
December 14, 2017: Organic Letters
https://www.readbyqxmd.com/read/29240415/identifying-plant-stress-responses-to-roxarsone-in-soybean-root-exudates-new-insights-from-two-dimensional-correlation-spectroscopy
#9
Qing-Long Fu, Lee Blaney, Dong-Mei Zhou
Roxarsone (ROX) is an organoarsenic feed additive of increasing interest used in the poultry industry. Soybean responses to ROX stress were investigated in root exudates (REs) using two-dimensional correlation spectroscopy (2D-COS) with fluorescence and Fourier transform infrared spectra. Environmentally-relevant ROX concentrations caused negligible toxicity to crop growth and photosynthesis activity, but blackened soybean roots at high concentrations. 2D-COS analysis revealed that the protein-like fluorophore and C=C and C=O, aliphatic-OH, and polysaccharide C-O-H moieties in soybean REs were most sensitive to ROX stress...
December 14, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/29239616/tertiary-and-quaternary-carbon-formation-via-gallium-catalyzed-nucleophilic-addition-of-organoboronates-to-cyclopropanes
#10
Truong N Nguyen, Jeremy A May
GaCl3 and (IPr)GaCl3/AgSbF6 formed γ-tertiary and γ-quaternary carbons via homoconjugate addition of organoboron nucleophiles to diester- and ketone-functionalized cyclopropanes. Electron donor group cyclopropane substituents were not needed, allowing electron-deficient aryl, alkenyl, alkyl, and hydrogen-substituted cyclopropanes to be used. The catalytic conditions were compatible with alkenyl, alkynyl, and aryl nucleophiles, including ortho-substituted aromatics, to synthesize highly hindered quaternary carbons...
December 14, 2017: Organic Letters
https://www.readbyqxmd.com/read/29239507/synthesis-of-%C3%AE-chiral-ketones-and-chiral-alkanes-using-radical-polar-crossover-reactions-of-vinyl-boron-ate-complexes
#11
Carolin Gerleve, Marvin Kischkewitz, Armido Studer
Vinyl boron ate complexes of enantioenriched secondary alkyl pinacolboronic esters undergo stereospecific radical induced 1,2-migration in radical polar crossover reactions. In this three component process various commercially available alkyl iodides act as radical precursors and light is used for chain initiation. A subsequent oxidation or protodeborylation leads to valuable α-chiral ketones and chiral alkanes with excellent enantiopurity.
December 14, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29239185/chemoselective-reduction-of-sterically-demanding-n-n-di-iso-propyl-amides-to-aldehydes
#12
Peihong Xiao, Zhixing Tang, Kai Wang, Hua Chen, Qianyou Guo, Yang Chu, Lu Gao, Zhenlei Song
A sequential one-pot process for chemoselectively reducing sterically demanding N,N-di(iso-propyl) amides to aldehydes has been developed. In this reaction, amides are activated with EtOTf to form imidates, which are reduced with LiAlH(OR)3 [R = t-Bu, Et] to give aldehydes by hydrolysis of the resulting hemiaminals. The non-nucleophilic base 2,6-DTBMP remarkably improves reaction efficiency. The combination of EtOTf/2,6-DTBMP and LiAlH(Ot-Bu)3 was found to be optimal for reducing alkyl, alkenyl, alkynyl and 2-monosubstituted aryl N,N-di(iso-propyl) amides...
December 14, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29238872/characterization-of-two-carbonyl-reductases-from-ogataea-polymorpha-nbrc-0799
#13
Kimiyasu Isobe, Shinsuke Miki, Ryoko Ueda, Sayaka Shichida, Daisuke Matsui, Yuko Oku, Yasuhisa Asano
The enzyme responsible for the enantioselective production of (S)-1,1,1-trifluoro-2-propanol ((S)-TFP) from 1,1,1-trifluoroacetone (TFA) has been identified in Ogataea polymorpha NBRC 0799. We purified two carbonyl reductases, OpCRD-A and OpCRD-B from this strain, and revealed their characteristics. Both enzymes were specific to NADH, but the following characteristics were different: The molecular mass of subunit OpCRD-A was 40 kDa and that of OpCRD-B was 43 kDa. Amino acid sequences of both enzymes were only 21% identical...
December 13, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/29238767/real-time-monitoring-for-reforming-processes-of-liquid-hydrocarbon-fuel-air-pre-mixtures-by-non-thermal-plasmas-using-ion-attachment-mass-spectrometry
#14
Daiki Asakawa, Akira Kuramochi, Eiichi Takahashi, Naoaki Saito
Plasma induced reforming processes of fuel-air mixtures were investigated to understand the mechanism of the plasma-assisted combustion technique, which can improve the thermal efficiency and stability of internal combustion engines. In this study, a mixture of air with isooctane or n-heptane fuels was reformed by non-thermal plasma in a flow reactor, generated by a dielectric barrier discharge, and then directly analyzed using ion attachment mass spectrometry. Plasma irradiation of an air/hydrocarbon mixture produced an oxygen atom which then reacted with a hydrocarbon, leading to hydroxyl and alkyl radicals...
December 13, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29235869/correction-to-organocatalytic-enantioselective-cross-aldol-reaction-of-o-hydroxyarylketones-and-trifluoromethyl-ketones
#15
Pei Wang, Hong-Feng Li, Jia-Zhen Zhao, Zhi-Hong Du, Chao-Shan Da
No abstract text is available yet for this article.
December 13, 2017: Organic Letters
https://www.readbyqxmd.com/read/29235717/direct-asymmetric-michael-reaction-of-%C3%AE-%C3%AE-unsaturated-aldehydes-and-ketones-catalyzed-by-two-secondary-amine-catalysts
#16
Yujiro Hayashi, Nariyoshi Umekubo
Direct asymmetric Michael reaction of α,β-unsaturated aldehydes and ketones proceeds in the presence of two pyrrolidine-type catalysts, such as diphenylprolinol silyl ether and hydroxyproline, to afford synthetically useful δ-keto aldehydes with excellent diastereo- and enantioselectivities. Although there are several iminium ions and enamines in the reaction mixture, an iminium ion generated from the former catalyst reacts preferentially with an enamine generated from the latter catalyst.
December 13, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29235696/beyond-hydrofunctionalization-a-well-defined-calcium-compound-catalyzed-mild-and-efficient-carbonyl-cyanosilylation
#17
Sandeep Yadav, Ruchi Dixit, Kumar Vanka, Sakya S Sen
Organocalcium compounds have been reported as efficient catalysts for various transformations, for cases where one of the substrates contained a E-H (E=B, N, Si, P) bond. Here, we look at the possibility of employing an organocalcium compound for a transformation in which none of the precursors has a polar E-H bond. This study demonstrates the utilization of a well-defined amidinatocalcium iodide, [PhC(NiPr)2CaI] (1) for cyanosilylation of a variety of aldehydes and ketones with Me3SiCN under ambient conditions without the need of any co-catalyst...
December 13, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29234415/1h-nmr-based-serum-metabolomics-study-to-investigate-hepatoprotective-effect-of-qin-jiao-on-carbon-tetrachloride-induced-acute-hepatotoxicity-in-rats
#18
Zeyun Li, Ying Li, Lingpan Lu, Zhiheng Yang, Wenhua Xue, Xin Tian, Xiaojian Zhang
Gentiana macrophylla Radix, commonly known as Qin-Jiao (QJ), was recorded alone to treat jaundice in Compendium of Materia Medica and has been frequently prescribed for treatment of liver disease in China. However, the underlying mechanism remains unknown. In the present work, QJ of 1,2 g/kg or silybin of 40 mg/kg (positive control) was orally given to rats for 7 days to verify the protective effect on acute liver damage induced by tetrachloride (CCl4). Together with serum biochemistry and histopathological examination, 1H-NMR based metabolomics work was carried out to investigate the efficacy...
2017: Evidence-based Complementary and Alternative Medicine: ECAM
https://www.readbyqxmd.com/read/29230466/synthesis-and-reactions-of-4h-1-4-telluraborine
#19
Fu An Tsao, Douglas W Stephan
The B(C6F5)3-catalyzed reaction of the 1,4-telluraborine, Te(PhC[double bond, length as m-dash]C(C6F5))2BOCH2Ph 2 with PhSiH3 gives Te(PhC[double bond, length as m-dash]C(C6F5))2BH 3. Compound 3 acts as a synthetic precursor to Te(PhC[double bond, length as m-dash]C(C6F5))2BCl 4 and Te(PhC[double bond, length as m-dash]C(C6F5))2B(THF)(O3SCF3) 5. In addition, 3 undergoes reactions with alkenes, alkynes, ketones and aldehydes to give a series of hydroboration products, 6-16.
December 12, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29225776/the-sedentary-r-evolution-have-we-lost-our-metabolic-flexibility
#20
Jens Freese, Rainer Johannes Klement, Begoña Ruiz-Núñez, Sebastian Schwarz, Helmut Lötzerich
During the course of evolution, up until the agricultural revolution, environmental fluctuations forced the human species to develop a flexible metabolism in order to adapt its energy needs to various climate, seasonal and vegetation conditions. Metabolic flexibility safeguarded human survival independent of food availability. In modern times, humans switched their primal lifestyle towards a constant availability of energy-dense, yet often nutrient-deficient, foods, persistent psycho-emotional stressors and a lack of exercise...
2017: F1000Research
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