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Samuel Mesihää, Ilpo Rasanen, Ilkka Ojanperä
Gas chromatography (GC) hyphenated with nitrogen chemiluminescence detection (NCD) and quadrupole time-of-flight mass spectrometry (QTOFMS) was applied for the first time to the quantitative analysis of new psychoactive substances (NPS) in urine, based on the N-equimolar response of NCD. A method was developed and validated to estimate the concentrations of three metabolites of the common stimulant NPS α-pyrrolidinovalerophenone (α-PVP) in spiked urine samples, simulating an analysis having no authentic reference standards for the metabolites and using the parent drug instead for quantitative calibration...
February 27, 2018: Forensic Science International
Stephen P Muench, Martin van der Laan
In this issue of Molecular Cell, Roh et al. (2018) present a high-resolution cryo-EM structure of the nanodisc-reconstituted yeast Vo proton channel that provides important new insights into subunit arrangements and the proton translocation pathway in V-type ATPases.
March 15, 2018: Molecular Cell
Fátima Higuera-de-la-Tijera
BACKGROUND: Proton pump inhibitors are the most effective medical therapy for gastroesophageal reflux disease, but their onset of action may be slow. OBJECTIVES: To assess the available literature regarding the efficacy of omeprazole/sodium bicarbonate in gastroesophageal reflux patients. METHODS: A systematic review was conducted. A systematic literature search starting from 2000. Reviewed manuscripts concerning the effectiveness of omeprazole/sodium bicarbonate treatment in gastroesophageal reflux disease were reviewed and the data were extracted...
March 14, 2018: Medwave
Sweet Ping Ng, Joseph M Herman
Pancreatic cancer is a devastating disease with poor survival outcomes. Recent studies have shown that the addition of radiotherapy to chemotherapy in the setting of locally advanced pancreatic cancer did not improve overall survival outcome. These studies commonly utilize conventional radiotherapy treatment fractionation and technique (typically 3-D conformal radiotherapy or intensity modulated radiotherapy). Although no clear benefit in overall survival was demonstrated in those studies, those who received radiotherapy did have a clear benefit in terms of local control...
March 16, 2018: Cancers
Hans G Rinderknecht, H-S Park, J S Ross, P A Amendt, D P Higginson, S C Wilks, D Haberberger, J Katz, D H Froula, N M Hoffman, G Kagan, B D Keenan, E L Vold
The structure of a strong collisional shock front forming in a plasma is directly probed for the first time in laser-driven gas-jet experiments. Thomson scattering of a 526.5 nm probe beam was used to diagnose temperature and ion velocity distribution in a strong shock (M∼11) propagating through a low-density (ρ∼0.01  mg/cc) plasma composed of hydrogen. A forward-streaming population of ions traveling in excess of the shock velocity was observed to heat and slow down on an unmoving, unshocked population of cold protons, until ultimately the populations merge and begin to thermalize...
March 2, 2018: Physical Review Letters
Chun-Yu Wang, Shuai Jiang, Yi-Rong Liu, Hui Wen, Zhongquan Wang, Ya-Juan Han, Teng Huang, Wei Huang
Ammonia and amines are important common trace atmospheric species that can enhance new particle formation (NPF) in the Earth's atmosphere. However, the synergistic effect of these two bases involving nucleation is still lacking. We studied the most stable geometric structures and thermodynamics of quaternary (NH3)(CH3NH2)(H2SO4)m(H2O)n (m = 1-3, n = 0-4) clusters at the PW91PW91/6-311++G(3df,3pd) level of theory for the first time. We find that the proton transfer from H2SO4 molecule to CH3NH2 molecule is easier than to NH3 molecule in the free or hydrated H2SO4-base clusters, and thus leads to the stability...
March 16, 2018: Journal of Physical Chemistry. A
Robert M B Dyer, Philip L Hahn, Michael K Hilinski
The first examples of nonenzymatic N-oxidation of heteroarenes in the presence of amines are reported. Pyridine, quinoline, and isoquinoline N-oxides are selectively formed in the presence of more reactive aliphatic and alicyclic amines by use of an in situ protonation strategy and an iminium salt organocatalyst. Application to late-stage functionalization that mimics phase 1 metabolism of small-molecule drugs is also demonstrated.
March 16, 2018: Organic Letters
Tibor Gyori, Balazs Olasz, Gabor Paragi, Gabor Czako
Accuracy of the different levels of electronic structure theory is frequently studied for stationary-point properties, however, little is known about the effects of the electronic structure methods and basis sets on the dynamics of chemical reactions. Here we report such an investigation for the F- + CH3 I SN 2 and proton-transfer reactions by developing 20 different analytical potential energy surfaces (PESs) obtained at the HF/DZ, HF/TZ, HF-D3(BJ)/DZ, HF-D3(BJ)/TZ, MP2/DZ, MP2/TZ, MP2-F12/DZ, MP2-F12/TZ, CCSD/DZ, CCSD-F12b/DZ, CCSD(T)/DZ, CCSD(T)-F12b/DZ, OQVCCD(T)/DZ, B97-1/TZ, PBE0/TZ, PBE0-D3(BJ)/TZ, M06-2X/TZ, M06-2X-D3(0)/TZ, B2PLYP/TZ, and B2PLYP-D3(BJ)/TZ levels of theory, where DZ and TZ denote the aug-cc-pVDZ and aug-cc-pVTZ basis sets with a relativistic effective core potential and the corresponding bases for iodine...
March 16, 2018: Journal of Physical Chemistry. A
Evgenia N Nikolova, Robyn L Stanfield, Jane Dyson, Peter E Wright
Many eukaryotic transcription factors recognize the epigenetic marker 5-methylcytosine (mC) at CpG sites in DNA. Despite their structural diversity, methyl-CpG-binding proteins (MBPs) share a common mode of recognition of mC methyl groups that involves hydrophobic pockets and weak hydrogen bonds of the CH---O type. The zinc finger protein Kaiso possesses a remarkably high specificity for methylated over unmethylated CpG sites. A key contribution to this specificity is provided by glutamate 535 (E535), which is optimally positioned to form multiple interactions with mCpG, including direct CH---O hydrogen bonds...
March 16, 2018: Biochemistry
Hsuan-Ming Huang, Chih-Chieh Liu, Meei-Ling Jan, Ming-Wei Lee
The Compton camera is an imaging device which has been proposed to detect prompt gammas (PGs) produced by proton-nuclear interactions within tissue during proton beam irradiation. Compton-based PG imaging has been developed to verify proton range because PG rays, particularly characteristic ones, have strong correlations with the distribution of the proton dose. However, accurate image reconstruction from characteristic PGs is challenging because the detector efficiency and resolution are generally low. Our previous study showed that point spread functions can be incorporated into the reconstruction process to improve image resolution...
March 16, 2018: Physics in Medicine and Biology
Patrícia Branco, Helena Albergaria, Nils Arneborg, Catarina Prista
Saccharomyces cerevisiae secretes antimicrobial peptides (AMPs) derived from glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which induce death of several non-Saccharomyces yeasts. Previously, we demonstrated that the naturally-secreted GAPDH-derived AMPs (i.e. saccharomycin) caused a loss of culturability and decreased the intracellular pH (pHi) of Hanseniaspora guilliermondii cells. In this study, we show that chemically-synthesized analogues of saccharomycin also induce a pHi drop and loss of culturability in H...
March 13, 2018: FEMS Yeast Research
Jian-Biao Liu, Ying-Ying Tian, Xin Zhang, Lu-Lin Wang, De-Zhan Chen
The detailed mechanism of palladium-catalyzed γ-C(sp3)-H olefination/cyclization of triflyl-protected amines was investigated by density functional theory (DFT) calculations. The olefinated intermediate was initially formed in the first catalytic cycle involving ligand exchange, bicarbonate-assisted C(sp3)-H bond cleavage, alkene insertion and 'reductive β-hydride elimination'. The following syn-addition and reductive elimination furnish the aza-Wacker product. The first step of reductive elimination is the rate-determining step...
March 16, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Angela Contreras, Magdalena Ribbeck, Guillermo D Gutiérrez, Pablo M Cañon, Sebastián N Mendoza, Eduardo Agosin
The effect of ethanol on the metabolism of Oenococcus oeni , the bacterium responsible for the malolactic fermentation (MLF) of wine, is still scarcely understood. Here, we characterized the global metabolic response in O. oeni PSU-1 to increasing ethanol contents, ranging from 0 to 12% (v/v). We first optimized a wine-like, defined culture medium, MaxOeno, to allow sufficient bacterial growth to be able to quantitate different metabolites in batch cultures of O. oeni . Then, taking advantage of the recently reconstructed genome-scale metabolic model iSM454 for O...
2018: Frontiers in Microbiology
Javier Molina-Infante, Carolina Gutierrez-Junquera, Edoardo Savarino, Roberto Penagini, Ines Modolell, Ottavia Bartolo, Alicia Prieto-García, Aurelio Mauro, Javier Alcedo, Antonia Perelló, Carlos Guarner-Argente, Noelia Alcaide, Ana M Vegas, Patricia Barros-García, Marianette Murzi-Pulgar, Monica Perona, Javier P Gisbert, Alfredo J Lucendo
OBJECTIVES: Rising trends in eosinophilic esophagitis (EoE) have been repeatedly linked to declining Helicobacter pylori (H. pylori) infection, mostly in retrospective studies. We aimed to prospectively evaluate this inverse association. METHODS: Prospective case-control study conducted in 23 centers. Children and adults naïve to eradication therapy for H. pylori were included. Cases were EoE patients, whereas controls were defined by esophageal symptoms and <5 eos/HPF on esophageal biopsies...
March 15, 2018: American Journal of Gastroenterology
Krista C J Wink, Erik Roelofs, Charles B Simone, David Dechambre, Alina Santiago, Judith van der Stoep, Wim Dries, Julia Smits, Stephen Avery, Filippo Ammazzalorso, Nicolas Jansen, Urszula Jelen, Timothy Solberg, Dirk de Ruysscher, Esther G C Troost
PURPOSE: To compare dose to organs at risk (OARs) and dose-escalation possibility for 24 stage I non-small cell lung cancer (NSCLC) patients in a ROCOCO (Radiation Oncology Collaborative Comparison) trial. METHODS: For each patient, 3 photon plans [Intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT) and CyberKnife], a double scattered proton (DSP) and an intensity-modulated carbon-ion (IMIT) therapy plan were created. Dose prescription was 60 Gy (equivalent) in 8 fractions...
March 12, 2018: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
Peter Nash, Philip J Mease, Iain B McInnes, Proton Rahman, Christopher T Ritchlin, Ricardo Blanco, Eva Dokoupilova, Mats Andersson, Radhika Kajekar, Shephard Mpofu, Luminita Pricop
BACKGROUND: The study aimed to assess 52-week efficacy and safety of secukinumab self-administration by autoinjector in patients with active psoriatic arthritis (PsA) in the FUTURE 3 study ( NCT01989468). METHODS: Patients (≥ 18 years of age; N = 414) with active PsA were randomized 1:1:1 to subcutaneous (s.c.) secukinumab 300 mg, 150 mg, or placebo at baseline, weeks 1, 2, 3, and 4, and every 4 weeks thereafter. Per clinical response, placebo-treated patients were re-randomized to s...
March 15, 2018: Arthritis Research & Therapy
Mark T Corkum, Wei Liu, David A Palma, Glenn S Bauman, Robert E Dinniwell, Andrew Warner, Mark V Mishra, Alexander V Louie
BACKGROUND: Cancer patients frequently search the Internet for treatment options, and hospital websites are seen as reliable sources of knowledge. Guidelines support the use of proton radiotherapy in specific disease sites or on clinical trials. This study aims to evaluate direct-to-consumer advertising content and claims made by proton therapy centre (PTC) websites worldwide. METHODS: Operational PTC websites in English were identified through the Particle Therapy Co-Operative Group website...
March 15, 2018: Radiation Oncology
Giovanni Rillo, Miguel A Morales, David M Ceperley, Carlo Pierleoni
We performed simulations for solid molecular hydrogen at high pressures (250 GPa ≤ P ≤ 500 GPa) along two isotherms at T = 200 K (phase III) and at T = 414 K (phase IV). At T = 200 K, we considered likely candidates for phase III, the C2c and Cmca12 structures, while at T = 414 K in phase IV, we studied the Pc48 structure. We employed both Coupled Electron-Ion Monte Carlo (CEIMC) and Path Integral Molecular Dynamics (PIMD). The latter is based on Density Functional Theory (DFT) with the van der Waals approximation (vdW-DF)...
March 14, 2018: Journal of Chemical Physics
Takashi Ikeda
The nuclear quantum effects (NQEs) on the structural, elastic, electronic, and vibrational properties of high pressure ices (HPIs) VIII, VII, and X at 270 K were investigated via first principles centroid molecular dynamics (CMD). Our simulations clearly show that even at relatively high temperature of 270 K, the NQEs play a definite role in the pressure-induced proton order (ice VIII)-disorder (ice VII) transition occurring at ∼30 GPa in our H2 O ice and the subsequent transition to the symmetric phase ice X suggested to occur at ∼80 GPa...
March 14, 2018: Journal of Chemical Physics
Yexin Feng, Zhichang Wang, Jing Guo, Ji Chen, En-Ge Wang, Ying Jiang, Xin-Zheng Li
Proton tunneling is an elementary process in the dynamics of hydrogen-bonded systems. Collective tunneling is known to exist for a long time. Atomistic investigations of this mechanism in realistic systems, however, are scarce. Using a combination of ab initio theoretical and high-resolution experimental methods, we investigate the role played by the protons on the chirality switching of a water tetramer on NaCl(001). Our scanning tunneling spectroscopies show that partial deuteration of the H2 O tetramer with only one D2 O leads to a significant suppression of the chirality switching rate at a cryogenic temperature (T), indicating that the chirality switches by tunneling in a concerted manner...
March 14, 2018: Journal of Chemical Physics
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