Read by QxMD icon Read


Jincai Zhao, Wanhong Ma
HO-adduct radicals have been investigated and confirmed as the common initial intermediates in TiO2 photocatalysis and Fenton degradations of water-insoluble aromatics. However, the evolution of HO-adduct radicals to phenols has not been completely clarified. In this study, we discovered that when 4-deuterium-toluene (4-d-toluene) and p-xylene were degraded by TiO2-photocatalysis and Fenton reactions, respectively, a portion of the 4-deuterium or 4-CH3 group (18~100%) at the attacked ipso position shifted to the adjacent position of the ring in the formed phenols (NIH shift)...
October 19, 2016: Chemistry, An Asian Journal
Rabi Chhantyal-Pun, Oliver Welz, John David Savee, Arkke J Eskola, Edmond P F Lee, Lucy Blacker, Henry R Hill, Matilda Ashcroft, M Anwar H H Khan, Guy C Lloyd-Jones, Louise A Evans, Brandon Rotavera, Haifeng Huang, David L Osborn, Daniel K W Mok, John M Dyke, Dudley E Shallcross, Carl John Percival, Andrew J Orr-Ewing, Craig Allen Taatjes
The Criegee intermediate acetone oxide, (CH3)2COO, is formed by laser photolysis of 2,2-diiodopropane in the presence of O2 and characterized by synchrotron photoionization mass spectrometry and by cavity ringdown ultraviolet absorption spectroscopy. The rate coefficient of the reaction of the Criegee intermediate with SO2 was measured using photoionization mass spectrometry and pseudo-first order methods to be (7.3 ± 0.5) × 10 11 cm3 s 1 at 298 K and 4 Torr and (1.5 ± 0.5) × 10 10 cm3 s 1 at 298 K and 10 Torr (He buffer)...
October 18, 2016: Journal of Physical Chemistry. A
Jihye Jung, Tibor Czabany, Birgit Wilding, Norbert Klempier, Bernd Nidetzky
The enzyme QueF catalyzes a four-electron reduction of a nitrile group into an amine, the only reaction of this kind known in biology. In nature, QueF converts 7-cyano-7-deazaguanine (preQ0) into 7-aminomethyl-7-deazaguanine (preQ1) for the biosynthesis of the tRNA-inserted nucleoside queuosine. The proposed QueF mechanism involves a covalent thioimide adduct between preQ0 and a cysteine nucleophile in the enzyme, and this adduct is subsequently converted into preQ1 in two NADPH-dependent reduction steps. Here, we show that the Escherichia coli QueF binds preQ0 in a strongly exothermic process (∆H = -80...
October 17, 2016: Journal of Biological Chemistry
Lena Davidsson, Jameela Al-Ghanim, Tareq Al-Ati, Nawal Al-Hamad, Anwar Al-Mutairi, Lulwa Al-Olayan, Thomas Preston
The aim of this pilot study was to assess body composition and total energy expenditure (TEE) in 35 obese 7-9 years old Kuwaiti children (18 girls and 17 boys). Total body water (TBW) and TEE were assessed by doubly-labeled water technique. TBW was derived from the intercept of the elimination rate of deuterium and TEE from the difference in elimination rates of (18)O and deuterium. TBW was used to estimate fat-free mass (FFM), using hydration factors for different ages and gender. Fat mass (FM) was calculated as the difference between body weight and FFM...
October 13, 2016: International Journal of Environmental Research and Public Health
Bachir Latli, Michael Stiasni, Matt Hrapchak, Zhibin Li, Nelu Grinberg, Heewon Lee, Carl A Busacca, Chris H Senanayake
Hyosine butyl bromide, the active ingredient in Buscopan, is an anticholinergic and antimuscarinic drug used to treat pain and discomfort caused by abdominal cramps. A straightforward synthesis of carbon-14- and deuterium-labeled Buscopan was developed using scopolamine, n-butyl-1-(14) C bromide, and n-butyl-(2) H9 bromide, respectively. In a second carbon-14 synthesis, the radioactive carbon was incorporated in the tropic acid moiety to follow its metabolism. Herein, we describe the detailed preparations of carbon-14- and deuterium-labeled Buscopan...
October 17, 2016: Journal of Labelled Compounds & Radiopharmaceuticals
Kai Sun, Chao Fang, Weicheng Yang, Zhongjie Xu, Haoran Wang, Wen Sun, Yong Luo, Yi Xu
This report presents an efficient synthesis of D6 -clenproperol and D6 -cimaterol with 99.5% and 99.7% isotopic abundance in acceptable yields and excellent chemical purities with deuterium isopropylamine as labelled precursor. Their structures and the isotope-abundance were confirmed by proton nuclear magnetic resonance and liquid chromatography-mass spectrometry.
October 17, 2016: Journal of Labelled Compounds & Radiopharmaceuticals
Rane A Harrison, Jia Lu, Martin Carrasco, John Hunter, Anuj Manandhar, Sudershan Gondi, Kenneth D Westover, John R Engen
Structural dynamics of Ras proteins contribute to their activity in signal transduction cascades. Directly targeting Ras proteins with small molecules may rely on movement of a conserved structural motif, switch II. To understand Ras signaling and advance Ras targeting strategies, experimental methods to measure Ras dynamics are required. Here we demonstrate the utility of hydrogen-deuterium exchange mass spectrometry to measure Ras dynamics by studying representatives from two branches of the Ras superfamily, Ras and Rho...
October 14, 2016: Journal of Molecular Biology
Mengzhe Guo, Dengyang Yin, Jie Han, Cheng Guo, Xiao Li, Liyan Zhang, Yan Du, Haibo Wang, Daoquan Tang
RATIONALE: Mass spectrometry has been developed as one of the common tools for the analysis of the organometallic systems in the gas phase over decades. The study of the fragmentation of organics-metal complexes has attracted much attention since the interesting dissociation pathways exhibited by these compounds are usually different from the protonated analogues. METHODS: In this work, iohexol complexed with different dications such as Mg(2+) , Cu(2+) , and Zn(2+) have been investigated by ESI tandem mass spectrometry...
October 17, 2016: Rapid Communications in Mass Spectrometry: RCM
Martin Waterstraat, Andreas A Hildebrand, Margit Rosler, Mirko Bunzel
Forage plants of the Poaceae family are grown as pasturage or used for the production of hay, straw, corn stover, etc. Although ferulic acid contents of grasses are generally high, the amount of ingested ferulic acid differs depending on the type of forage resulting in varying contents of ferulic acid and its microbial and hepatic metabolites in milk. Concentrations and patterns of these metabolites may be used as markers to track different forages in livestock feeding. Therefore, we developed a stable isotope dilution assay to quantitate ferulic acid, twelve ferulic acid based metabolites, p coumaric acid, and cinnamic acid in milk...
October 15, 2016: Journal of Agricultural and Food Chemistry
Kms Kanhai, S C Goulooze, J Stevens, J L Hay, G Dent, A Verma, T Hankemeier, T de Boer, H Meijering, J C Chavez, A F Cohen, G J Groeneveld
Therapeutics promoting myelin synthesis may enhance recovery in demyelinating diseases, such as multiple sclerosis. However, no suitable method exists to quantify myelination. The turnover of galactosylceramide (myelin component) is indicative of myelination in mice, but its turnover has not been determined in humans. Here, six healthy subjects consumed 120 mL 70% D2 O daily for 70 days to label galactosylceramide. We then used mass spectrometry and compartmental modeling to quantify the turnover rate of galactosylceramide in cerebrospinal fluid...
October 15, 2016: Clinical and Translational Science
Haruki Nagae, Wataru Hato, Kento Kawakita, Hayato Tsurugi, Kazushi Mashima
Dinuclear titanium dialkyl complexes bridged by two μ-arylimido ligands, [CpTi(CH₂SiMe₃)(μ-NAr)]₂ (2), activated an ortho-phenyl C-H bond of an μ-arylimido ligand to form a 4-membered titanacycle. Subsequent insertion reaction of 1-(trimethylsilyl)propyne into a metal-carbon bond of the 4-membered titanacycle yielded the corresponding 6-membered titanacycle. Further ortho-C-H bond activation of the other μ-arylimido ligand and an insertion reaction proceeded to give dinuclear titanium complexes 3 with two 6-membered titanacycles...
October 14, 2016: Chemistry: a European Journal
Zhigang Wang, Zhenguo Fu, Bin He, Zehua Hu, Ping Zhang
The nuclear plus interference scattering (NIS) effect on the stopping power of hot dense beryllium (Be) plasma for multi-MeV protons is theoretically investigated by using the generalized Brown-Preston-Singleton (BPS) model, in which a NIS term is taken into account. The analytical formula of the NIS term is detailedly derived. By using this formula, the density and temperature dependence of the NIS effect is numerically studied, and the results show that the NIS effect becomes more and more important with increasing the plasma temperature or density...
September 2016: Physical Review. E
Erich Hellemann, Rubens R Teles, Fernando Hallwass, W Barros, Armando Navarro-Vázquez, Roberto R Gil
Anisotropic NMR parameters, such as residual dipolar couplings (RDCs), residual chemical shift anisotropies (RCSAs) and residual quadrupolar couplings (RQCs or ΔνQ ), appear in solution-state NMR when the molecules under study are subjected to a degree of order. The tunable alignment by reversible compression/relaxation of gels (PMMA and p-HEMA) is an easy, user-friendly, and very affordable method to measure them. When using this method, a fraction of isotropic NMR signals is observed in the NMR spectra, even at a maximum degree of compression...
October 14, 2016: Chemistry: a European Journal
Takahide Fukuyama, Yuki Fujita, Muhammad Abid Rashid, Ilhyong Ryu
A Cossy 5-exo-dig photocyclization of organohalides (X = Br, I) onto a C-C triple bond was studied using a flow photomicroreactor, which proceeded in a minute order of residence time. A deuterium labeling study supported the nonchain radical mechanism proposed by the Cossy group, in which a hydrogen source originates from a triethylamine cation radical. Scalable flow synthesis using a larger volume of flow reactor was also successful, providing 4 g of the product in high yield.
October 13, 2016: Organic Letters
Adama Diouf, Mbeugué Thiam, Nicole Idohou-Dossou, Ousmane Diongue, Ndé Mégné, Khady Diallo, Pape Malick Sembène, Salimata Wade
Background: Physical inactivity and sedentary lifestyles are major risk factors of childhood obesity. This study aimed to measure physical activity (PA) levels by accelerometer and Physical Activity Questionnaire for Older Children (PAQ-C) among Senegalese school children and the relation with Body Mass Index (BMI) and body composition. Methodology: 156 pupils 8-11 years old were randomly selected in four elementary public schools of Dakar. BMI z-score was used to categorize children according to their weight status...
October 10, 2016: International Journal of Environmental Research and Public Health
Junjie Li, Alexander B Pacheco, Krishnan Raghavachari, Srinivasan S Iyengar
We probe the structure, stability and vibrational properties of the fundamental C2H3(+) carbocation that exists with preference in a bridged hydrogen conformation. Our computational study includes electronic structure treatment, incorporation of nuclear motion through classical and quantum paradigms, the effect of temperature, and the associated sampling of the potential surface, and the effect of single H/D isotopic substitution (i.e., C2H2D(+)). We find that while the non-classical, "Bridged" isomer is most stable, the "Classical" form does have a small presence under ambient conditions since the zero point level straddles the barrier between the Classical and Bridged isomers in a reduced dimensional analysis of the Bridged ↔ Classical transfer coordinate...
October 13, 2016: Physical Chemistry Chemical Physics: PCCP
Younis F Hamad Abiedalla, Karim Abdel-Hay, Jack DeRuiter, C Randall Clark
A combination of GC-MS, MS/MS and GC-IR techniques were used to characterize the ring substitution pattern, the alkyl side-chain and the cyclic tertiary amine portions of a series of six homologous and regioisomeric methylenedioxyphenyl-aminoketones related to the designer drug, 3,4-methylenedioxypyrovalerone (MDPV). Chromatographic retention increases with the hydrocarbon content of the alkyl side-chain and the 3,4-methylenedioxy substitution pattern shows higher retention than the corresponding 2,3-methylenedioxy isomer...
October 12, 2016: Journal of Chromatographic Science
Tycho E T Mevissen, Yogesh Kulathu, Monique P C Mulder, Paul P Geurink, Sarah L Maslen, Malte Gersch, Paul R Elliott, John E Burke, Bianca D M van Tol, Masato Akutsu, Farid El Oualid, Masato Kawasaki, Stefan M V Freund, Huib Ovaa, David Komander
The post-translational modification of proteins with polyubiquitin regulates virtually all aspects of cell biology. Eight distinct chain linkage types co-exist in polyubiquitin and are independently regulated in cells. This 'ubiquitin code' determines the fate of the modified protein. Deubiquitinating enzymes of the ovarian tumour (OTU) family regulate cellular signalling by targeting distinct linkage types within polyubiquitin, and understanding their mechanisms of linkage specificity gives fundamental insights into the ubiquitin system...
October 12, 2016: Nature
S S V Ramasastry, Raghu Moluguri, Jagdeep Grover
A new approach for the cyclopenta[b]annulation of heteroarenes via metal-free and directing group-free γ'[C(sp3)-H] functionalization and intramolecular hydroalkylation of ynones has been developed. In an unprecedented event, nucleophilic addition of an organophosphine to the designed ynones triggers γ'[C(sp3)-H] functionalization, leading to the formation of heteroaryl-based ortho-quinodimethane (oQDM) intermediates, which undergo carbocyclization to provide cyclopentannulated heteroarenes in good yields and excellent stereoselectivities...
October 12, 2016: Chemistry: a European Journal
Ursula Schulze-Gahmen, Ignacia Echeverria, Goran Stjepanovic, Yun Bai, Huasong Lu, Dina Schneidman-Duhovny, Jennifer A Doudna, Qiang Zhou, Andrej Sali, James H Hurley
HIV-1 Tat hijacks the human superelongation complex (SEC) to promote proviral transcription. Here we report the 5.9 Å structure of HIV-1 TAR in complex with HIV-1 Tat and human AFF4, CDK9, and CycT1. The TAR central loop contacts the CycT1 Tat-TAR recognition motif (TRM) and the second Tat Zn(2+)-binding loop. Hydrogen-deuterium exchange (HDX) shows that AFF4 helix 2 is stabilized in the TAR complex despite not touching the RNA, explaining how it enhances TAR binding to the SEC 50-fold. RNA SHAPE and SAXS data were used to help model the extended (Tat Arginine-Rich Motif) ARM, which enters the TAR major groove between the bulge and the central loop...
October 12, 2016: ELife
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"