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Eugene P Sokolov, Inna M Sokolova
Salinity is an important environmental factor affecting physiology of marine organisms. Osmoconformers such as marine mollusks maintain metabolic function despite changes of the osmolarity and composition of the cytosol during salinity shifts. Currently, metabolic responses to the salinity-induced changes of the intracellular milieu are not well understood. We studied the effects of osmolarity (450 vs. 900 mOsm) and compatible osmolytes (70-590 mM of taurine or betaine) on isolated gill mitochondria of a marine osmoconformer, the Pacific oyster Crassostrea gigas...
February 16, 2018: Mitochondrion
Kumar Padmapriya, Ritu Barthwal
Plant derived small molecules, which interact with and stabilize G-quadruplex DNA, act as inhibitors of telomere elongation and oncogene expression in humans. The inhibition of telomerase enzyme has immense potential since it is over expressed in most cancer cells. Interaction of palmatine, an antitumor alkaloid, to parallel G-quadruplex DNA, [d(TTGGGGT)]4 and [d(TTAGGGT)]4 , has been investigated using Nuclear Magnetic Resonance (NMR), fluorescence and Circular Dichroism (CD) spectroscopy. Titrations were monitored by1 H and31 P NMR spectra and solution structure of palmatine-[d(TTGGGGT)]4 complex was obtained by restrained Molecular Dynamics (rMD) simulations using distance restraints from 2D NOESY spectra...
February 16, 2018: Biochimie
Yande Huang, Qinggang Wang, Yongmei Wu
Degradation of an active pharmaceutical ingredient (API), a 2-(3-(1-(4-chlorophenyl)cyclopropyl)-[1,2,4]triazolo[4,3-a]pyridin-8-yl)propan-2-ol hydrochloride salt, was observed in a capsule formulation stressed at 50°C or 40°C/75% relative humidity conditions for one month. Two unknown degradants were identified as cationic pseudodimers of the API via accurate mass liquid chromatography-mass spectrometry and one- and two-dimensional NMR analyses. A plausible degradation pathway of the API was postulated which led to the identification of two key N-oxide degradants in the stressed capsule formulation at trace levels...
February 16, 2018: Journal of Pharmaceutical Sciences
John M Robbins, Andreas S Bommarius, Giovanni Gadda
Formate oxidase (FOX) from Aspergillus oryzae is the only GMC member that oxidizes a carbon acid rather than alcohols; thus, its catalytic mechanism may be different from that of other GMC members. We have used pH, solvent viscosity, and deuterium kinetic isotope effects, to investigate the catalytic mechanism of FOX. The enzyme followed a Bi-Bi sequential steady-state kinetic mechanism. The kcat value was pH-independent between pH 2.8 and 6.8, suggesting lack of ionizable groups in kinetic step(s) that limit the overall turnover of the enzyme...
February 16, 2018: Archives of Biochemistry and Biophysics
Ting-Husn Tu, Yi-Ting Chen, Jiun-Yi Shen, Ta-Chun Lin, Pi-Tai Chou
In this study, we investigated the excited-state proton transfer (ESPT) reaction for 3-cyano-7-azaindole (3CAI) in aqueous solution and in ice. 3CAI undergoes water catalyzed ESPT in the aqueous solution, giving normal (355 nm) and proton transfer tautomer (~472 nm) emission bands. Detailed temperature dependent studies showed that the values of activation free energy (△G≠) were similar between N-H and N-D isotope. Therefore, water catalyzed ESPT involves a stepwise mechanism incorporating solvation equilibrium (Keq) to form a 1:1 (molar ratio) water: 3CAI cyclic hydrogen bonded complex as an intermediate, followed by perhaps proton tunneling reaction...
February 19, 2018: Journal of Physical Chemistry. A
Guillaume David, Marie-Laure Fogeron, Maarten Schledorn, Roland Montserret, Uta Haselmann, Susanne Penzel, Aurelie Badillo, Lauriane Lecoq, Patrice André, Michael Nassal, Ralf Bartenschlager, Beat H Meier, Anja Böckmann
Viral membrane proteins are prime targets in the combat against infection. Still, their structure determination remains a challenge, both with respect to sample preparation, and the need for structural methods allowing analysis in a native-like lipid environment. Cell-free protein synthesis and solid-state NMR are promising approaches in this context, one with respect to its high potential of native expression of complex proteins, and the other for its ability to analyze membrane proteins in lipids. We here show that milligram amounts of the small envelope protein of the duck hepatitis B virus (DHBV) can be produced using cell-free expression, and that the protein self-assembles into subviral particles...
February 19, 2018: Angewandte Chemie
James R Banigan, Maureen Leninger, Ampon Sae Her, Nathaniel J Traaseth
It is known that the lipid composition within a cellular membrane can influence membrane protein structure and function. In this Article, we investigated how structural changes to a membrane protein upon substrate binding can impact the lipid bilayer. To carry out this study, we reconstituted the secondary active drug transporter EmrE into a variety of phospholipid bilayers varying in headgroup and chain length and carried out differential scanning calorimetry (DSC) and solid-state NMR experiments. The DSC results revealed a difference in cooperativity of the lipid phase transition for drug-free EmrE protonated at glutamic acid 14 (i...
February 19, 2018: Journal of Physical Chemistry. B
Evgenii Stoyanov, Irina S Stoyanova
Experimental study on protonation of simple weakly basic molecules (L) by the strongest solid superacid, H(CHB11F11), showed that basicity of SO2 is high enough (during attachment to the acidic H atoms at partial pressure of 1 atm) to break the bridged H-bonds of the polymeric acid and to form a mixture of solid mono- and disolvates, LH+‧‧‧An- and L-H+-L. With a decrease in the basicity of L = CO (via C), N2O, and CO (via O), only proton monosolvates are formed, which approach L-H+-An species with convergence of the strengths of bridged H-bonds...
February 19, 2018: Angewandte Chemie
Kentaro Yamamoto, Kazuo Takatsuka
We theoretically studied the chemical principles behind the photodynamics of water splitting: 2H2 O + 4hν + M → 4H+ + 4e- + O2 + M. To comprehend this simple looking but very complicated reaction, the mechanisms of at least three crucial phenomena, among others, need to be clarified, each of which is supposed to constitute the foundation of chemistry: (i) charge separation (4H+ + 4e- ), (ii) the catalytic cycle for essentially the same reactions to be repeated by each of four photon absorptions with a catalyst M, and (iii) the generation of oxygen molecules of spin triplet...
February 19, 2018: Physical Chemistry Chemical Physics: PCCP
Radwan A Hafiz, Chia Wong, Stuart Paynter, Michael David, Geeske Peeters
BACKGROUND: Previous meta-analyses suggest that users of proton pump inhibitors (PPIs) have a higher risk of developing enteric infections compared with nonusers. These previous meta-analyses have considerable heterogeneity, and it is not clear whether the effect of PPIs is different for different types of microorganisms. OBJECTIVE: The aim of this study is to update previous meta-analyses, concentrating on enteric infection in community settings and exploring potential sources of heterogeneity...
February 1, 2018: Annals of Pharmacotherapy
Hai Chao Yu, He Zhang, Ke-Feng Ren, Zhimin Ying, Fengbo Zhu, Jin Qian, Jian Ji, Zi Liang Wu, Qiang Zheng
Designing tough biopolymer-based hydrogels as structural biomaterials has both scientific and practical significances. We report a facile approach to prepare polysaccharide-based hydrogel films with remarkable mechanical performances and anti-adhesion property. The hydrogel films with thickness of 40-60 μm were prepared by mixing aqueous solutions of κ-carrageenan (κ-CG) and protonated chitosan (CS), evaporating the solvent, and then swelling the casted film in water to achieve the equilibrium state. The obtained κ-CG/CS gel films with water content of 48-88 wt% possessed excellent mechanical properties superior to most existing biopolymer-based hydrogels, with breaking stress of 2-6...
February 19, 2018: ACS Applied Materials & Interfaces
Francesca Pennati, David J Roach, John P Clancy, Alan S Brody, Robert J Fleck, Andrea Aliverti, Jason C Woods
BACKGROUND: Lung disease is the most frequent cause of morbidity and mortality in patients with cystic fibrosis (CF), and there is a shortage of sensitive biomarkers able to regionally monitor disease progression and to assess early responses to therapy. PURPOSE: To determine the feasibility of noncontrast-enhanced multivolume MRI, which assesses intensity changes between expiratory and inspiratory breath-hold images, to detect and quantify regional ventilation abnormalities in CF lung disease, with a focus on the structure-function relationship...
February 19, 2018: Journal of Magnetic Resonance Imaging: JMRI
Florian Wiesinger, Mikael Bylund, Jaewon Yang, Sandeep Kaushik, Dattesh Shanbhag, Sangtae Ahn, Joakim H Jonsson, Josef A Lundman, Thomas Hope, Tufve Nyholm, Peder Larson, Cristina Cozzini
PURPOSE: To describe a method for converting Zero TE (ZTE) MR images into X-ray attenuation information in the form of pseudo-CT images and demonstrate its performance for (1) attenuation correction (AC) in PET/MR and (2) dose planning in MR-guided radiation therapy planning (RTP). METHODS: Proton density-weighted ZTE images were acquired as input for MR-based pseudo-CT conversion, providing (1) efficient capture of short-lived bone signals, (2) flat soft-tissue contrast, and (3) fast and robust 3D MR imaging...
February 18, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Yanli Ma, Wenge Zhao, Changhe Shi, Ning Wang, Tianli Fan
The effects of human immunodeficiency virus (HIV) on the metabolic and biological pathways of cluster of differentiation (CD)4+ T lymphocytes were investigated. A total of 150 patients with acquired immune deficiency syndrome (AIDS) and 50 healthy individuals who were admitted to hospital for physical examination during the period of June 2016 to January 2017, were selected as subjects in the present study. According to the virus load, 150 AIDS patients were divided into three groups: i) Viral load >106 copies/ml (group A, n=39), ii) 104 copies/ml < viral load <105 copies/ml (group B, n=76), and iii) viral load <104 copies/ml (group C, n=35)...
March 2018: Experimental and Therapeutic Medicine
Wei Zhang, Xin Jin, Heng Li, Run-Run Zhang, Cheng-Wei Wu
Hydrogels based on chitosan/hyaluronic acid/β-sodium glycerophosphate demonstrate injectability, body temperature sensitivity, pH sensitive drug release and adhesion to cancer cell. The drug (doxorubicin) loaded hydrogel precursor solutions are injectable and turn to hydrogels when the temperature is increased to body temperature. The acidic condition (pH 4.00) can trigger the release of drug and the cancer cell (Hela) can adhere to the surface of the hydrogels, which will be beneficial for tumor site-specific administration of drug...
April 15, 2018: Carbohydrate Polymers
Jie Wang, Chunli Gong, Sheng Wen, Hai Liu, Caiqin Qin, Chuanxi Xiong, Lijie Dong
Poor dispersion and inert ionic conduction are two major obstacles towards using carbon nanotubes (CNTs) to modify polymer electrolyte membranes (PEMs) in energy conversion devices. In this work, solvent-free carbon nanotube fluids (CNT fluids) with liquid-like behavior are prepared through an ion exchange method and incorporated into a chitosan (CS) matrix to fabricate composite membranes. The electrostatic interactions between SO3 - groups in the CNT fluids and NH2 groups in the CS matrix, in addition to the unique flow properties of the CNT fluids, promote the uniform dispersion of CNT fluids in the CS matrix...
April 15, 2018: Carbohydrate Polymers
Yuchao Zhang, Hongna Zhang, Anan Liu, Chuncheng Chen, Wenjing Song, Jincai Zhao
Photoelectrochemical (PEC) water oxidation has attracted heightened interest in solar fuel production. It is well accepted that water oxidation on hematite is mediated by surface trapped holes, characterized to be the high valent -Fe═O species. However, the mechanism of the subsequent rate-limiting O-O bond formation step is still a missing piece. Herein we investigate the reaction order of interfacial hole transfer by rate law analysis based on electrochemical impedance spectroscopy (EIS) measurement and probe the reaction intermediates by operando Fourier-transform infrared (FT-IR) spectroscopy...
February 21, 2018: Journal of the American Chemical Society
Tousif Hossen, Kalyanasis Sahu
The H-bonded coumarin 102 (C102)-phenol complex has been a model system to understanding the influence of H-bonding on photophysical processes. Zhao and Han first showed that significant H-bond strengthening occurs in the excited state and proposed the possibility of fluorescence quenching in the complex via internal conversion from a locally excited (LE) state to a low-lying charge transfer (CT) state. Later, we experimentally confirmed fluorescence quenching of C102-phenol complex in a non-polar solvent (cyclohexane)...
February 18, 2018: Journal of Physical Chemistry. A
Malihe Rostampour, Mahdi Sadeghi, Mohammadreza Aboudzadeh, Saeid Hamidi, Naser Soltani, Fatemeh Bolouri Novin, Ali Rahiminejad, Saeid Rajabifar
The63 Zn was produced by16.8 MeV proton irradiation of natural copper. Thick target yield for63 Zn in the energy range of 16.8 →12.2 MeV was 2.47 ± 0.12 GBq/μA.h. Reasonable agreement between achieved experimental data and theoretical value of thick target yield for63 Zn was observed. A simple separation procedure of63 Zn from copper target was developed using cation exchange chromatography. About 88 ± 5% of the loaded activity was recovered. The performance of FLUKA to reproduce experimental data of thick target yield of63 Zn is validated...
February 5, 2018: Applied Radiation and Isotopes
Abirami R Ganesan, M Shanmugam, Rajeev Bhat
Edible films were developed from seaweed polysaccharides (Kappaphycus alvarezii and Ulva fasciata). The total extracted yield of semi refined carrageenan (SRC) and ulvan polysaccharide was 31.55%, and 28.86%, with total carbohydrate being 78.08% and 82.43% in SRC and ulvan polysaccharides. Results of viscometric studies revealed molecular weight to be 210 kDa and 72 kDa for SRC and ulvan polysaccharides. Proton NMR studies showed presence of anhydro-d-galactopyranose and glucosidic linkages in SRC, while ulvan polysaccharide had rhamnose-3-sulfate, glucosyl and β-d-glucuronic acid...
February 15, 2018: International Journal of Biological Macromolecules
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