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Nuclear magnetic resonance

Michael Wesbrook Staude, David A Leonard, Jeffrey W Peng
Gram-negative bacteria resist β-lactam antibiotics primarily by deploying β-lactamase proteins that hydrolytically destroy the antibiotics. In clinical settings, these bacteria are producing variant β-lactamases with "gain of activity" mutations that inactivate a broader range of β-lactams. Learning how these mutations broaden substrate activity is important for coping with β-lactam resistance. Here, we investigate a gain of activity mutation in OXA-24/40, a carbapenem-hydrolyzing Class D β-lactamase (CHDL) in Acinetobacter baumannii...
October 26, 2016: Biochemistry
Gianluca Pontone, Giuseppe Muscogiuri, Daniele Andreini, Andrea I Guaricci, Marco Guglielmo, Saima Mushtaq, Andrea Baggiano, Edoardo Conte, Virginia Beltrama, Andrea Annoni, Alberto Formenti, Elisabetta Mancini, Mark G Rabbat, Mauro Pepi
The increased number of patients with coronary artery disease (CAD) in developed countries is of great clinical relevance and involves a large burden of the healthcare system. The management of these patients is focused on relieving symptoms and improving clinical outcomes. Therefore the ideal test would provide the correct diagnosis and actionable information. To this aim, several non-invasive functional imaging modalities are usually used as gatekeeper to invasive coronary angiography (ICA), but their diagnostic yield remains low with limited accuracy when compared to obstructive CAD at the time of ICA or invasive fractional flow reserve (FFR)...
December 2016: Current Treatment Options in Cardiovascular Medicine
W Reith, S Roumia, P Dietrich
CLINICAL/METHODICAL ISSUE: Cerebellar syndromes result in distinct clinical symptoms, such as ataxia, dysarthria, dysmetria, intention tremor and eye movement disorders. STANDARD RADIOLOGICAL METHODS: In addition to the medical history and clinical examination, imaging is particularly important to differentiate other diseases, such as hydrocephalus and multi-infarct dementia from degenerative cerebellar diseases. Degenerative diseases with cerebellar involvement include Parkinson's disease, multiple system atrophy as well as other diseases including spinocerebellar ataxia...
October 25, 2016: Der Radiologe
Antoine Carof, Mathieu Salanne, Thibault Charpentier, Benjamin Rotenberg
Using molecular simulations, we analyze the microscopic processes driving the Nuclear Magnetic Resonance (NMR) relaxation of quadrupolar cations in water. The fluctuations of the Electric Field Gradient (EFG) experienced by alkaline and magnesium cations, which determine the NMR relaxation time, are mainly due to the dynamics of water molecules in their solvation shell. The dynamics of the ion plays a less important role, with the exception of the short-time dynamics in the lighter Li(+) case, for which rattling in the solvent cage results in oscillations of the EFG autocorrelation function (ACF)...
September 28, 2016: Journal of Chemical Physics
Anuraag Gaddam, Lionel Montagne, José M F Ferreira
In this paper, we derive a new model to determine the distribution of silicate units in binary glasses (or liquids). The model is based on statistical mechanics and assumes grand canonical ensemble of silicate units which exchange energy and network modifiers from the reservoir. This model complements experimental techniques, which measure short range order in glasses such as nuclear magnetic resonance (NMR) spectroscopy. The model has potential in calculating the amounts of liquid-liquid phase segregation and crystal nucleation, and it can be easily extended to more complicated compositions...
September 28, 2016: Journal of Chemical Physics
Naoki Ichijo, Kazuyuki Takeda, Kazuhiko Yamada, K Takegoshi
We propose a simple data-analysis scheme to determine the coupling constant and the asymmetry parameter of nuclear quadrupolar interactions in field-swept nuclear magnetic resonance (NMR) for static powder samples. This approach correlates the quadrupolar parameters to the positions of the singularities, which can readily be found out as sharp peaks in the field-swept pattern. Moreover, the parameters can be determined without quantitative acquisition and elaborate calculation of the overall profile of the pattern...
October 7, 2016: Journal of Chemical Physics
Aurélien Bornet, Arthur Pinon, Aditya Jhajharia, Mathieu Baudin, Xiao Ji, Lyndon Emsley, Geoffrey Bodenhausen, Jan Henrik Ardenkjaer-Larsen, Sami Jannin
Dissolution dynamic nuclear polarization (D-DNP) has become a method of choice to enhance signals in nuclear magnetic resonance (NMR). Recently, we have proposed to combine cross-polarization (CP) with D-DNP to provide high polarization P((13)C) in short build-up times. In this paper, we show that switching microwave irradiation off for a few hundreds of milliseconds prior to CP can significantly boost the efficiency. By implementing microwave gating, (13)C polarizations on sodium [1-(13)C]acetate as high as 64% could be achieved with a polarization build-up time constant as short as 160 s...
October 26, 2016: Physical Chemistry Chemical Physics: PCCP
Lingamallu Giribabu, Shivaprasad Achary B, Gokulnath Sabapathi, Samrat Ghosh, Madoori Mrinalini, Prasamthkumar Seelam
Charge-transfer (CT) complex of near-infrared absorbing systems hitherto unknown. Consequently, structural similarities between donor and acceptor are rather important to achieve this phenomenon. Herein, we reported electron donors such as non-fused diporphyrin-anthracene (DP), zinc diporphyrin-anthracene (ZnDP) and fused zinc diporphyrin-anthracene (FZnDP) in which FZnDP absorbs in NIR region and permits CT complex with electron acceptor, perylene diimide (PDI) in CHCl3 exclusively. UV-vis-NIR absorption, 1H nuclear magnetic resonance, nuclear overhauser effect spectroscopy and powder X-ray diffraction analysis demonstrated that the CT complex formation occurs by π-π stacking between perylene in FZnDP and PDI upon mixing together at 1:1 molar concentration in CHCl3, unlike non-fused ZnDP and DP...
October 26, 2016: Chemistry, An Asian Journal
Sai Zheng, Jia-Chen Shi, Jian-Ying Hu, Wen-Xin Hu, Jing Zhang, Bing Shao
The reaction kinetics and transformation pathways between bisphenol F (BPF) and sodium hypochlorite were investigated at pH values ranging from 6.5 to 8.5 and with different initial concentration ratios. The reaction rate was pH- and free available chlorine (FAC)-dependent: the reaction rate at pH 8.5 was almost 10 times than that at pH 6.5. A total of 40 compounds were tentatively identified as chloro-substituted BPF and polyphenolic compounds by liquid chromatography quadrupole time-of-flight mass spectrometry operating in electrospray ionization mode (LC-ESI-Q-ToF), and 4 main byproducts were confirmed by (1)H and (13)C nuclear magnetic resonance (NMR)...
October 19, 2016: Water Research
Filipa R Fernandes Simoes, Nitin Kumar Batra, Bashir H Warsama, Christian G Canlas, Shashikant Pandurang Patole, Tahir F Yapici, Pedro M F J Costa
Inductively coupled plasma optical emission spectroscopy (ICP-OES) is a common, relatively low cost and straightforward analytical technique for the study of trace quantities of metals in solid materials but its applicability to nanocarbons (e.g. graphene and nanotubes) has suffered from the lack of efficient digestion steps and certified reference materials (CRM). Here, various commercial and certified graphitic carbon materials were subjected to a "two-steps" microwave-assisted acid digestion procedure and the concentration of up to 18 elements was analysed by ICP-OES...
October 25, 2016: Analytical Chemistry
Bethany G Caulkins, Robert P Young, Ryan A Kudla, Chen Yang, Thomas J Bittbauer, Baback Bastin, Eduardo Hilario, Li Fan, Michael J Marsella, Michael F Dunn, Leonard J Mueller
Carbanionic intermediates play a central role in the catalytic transformations of amino acids performed by pyridoxal-5'-phosphate (PLP)-dependent enzymes. Here, we make use of NMR crystallography - the synergistic combination of solid-state nuclear magnetic resonance, X-ray crystallography, and computational chemistry - to interrogate a carbanionic/quinonoid intermediate analogue in the β-subunit active site of the PLP-requiring enzyme tryptophan synthase. The solid-state NMR chemical shifts of the PLP pyridine ring nitrogen and additional sites, coupled with first principles computational models, allow a detailed model of protonation states for ionizable groups on the cofactor, substrates, and nearby catalytic residues to be established...
October 25, 2016: Journal of the American Chemical Society
Qian Zhang, Junsong Wang, Chao Zhang, Shanting Liao, Pei Li, Dingqiao Xu, Yan Lv, Minghua Yang, Lingyi Kong
Huang-Lian-Jie-Du-Decoction (HLJDD, Oren-gedoku-to in Japanese) is commonly used in traditional Chinese medicine (TCM) to treat ischemic stroke. This study investigated the efficacy of various combinations of the major components of HLJDD, berberine (A), baicalin (B), and jasminoidin (C), on the treatment of ischemic stroke modeled by middle cerebral artery occlusion (MCAO) in rats. The effects of A, B and C individually and their combinations were investigated using proton nuclear magnetic resonance (1H NMR)-based metabolomics complemented with neurologic deficit scoring, infarct volume measurement, biochemistry, histopathology and immunohistochemistry, as well as quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting...
October 13, 2016: Oncotarget
Jang Hoon Kim, Ju-Yeon Yoon, Seo Young Yang, Seung-Kook Choi, Sun Jung Kwon, In Sook Cho, Min Hee Jeong, Young Ho Kim, Gug Seoun Choi
A new compound, 9-dihydroxyl-2'-O-(Z)-cinnamoyl-7-methoxy-aloesin (1), and eight known compounds (2-9) were isolated from Aloe vera. Their structures were elucidated using 1D/2D nuclear magnetic resonance and mass spectra. Compound 9 exhibited reversible competitive inhibitory activity against the enzyme tyrosinase, with an IC50 value of 9.8 ± 0.9 µM. A molecular simulation revealed that compound 9 interacts via hydrogen bonding with residues His244, Thr261, and Val283 of tyrosinase. Additionally, compounds 3 and 7 were shown by half-leaf assays to exhibit inhibitory activity towards Pepper mild mottle virus...
October 25, 2016: Journal of Enzyme Inhibition and Medicinal Chemistry
Emmanuel Amabebe, Steven Reynolds, Victoria Stern, Graham Stafford, Martyn Paley, Dilly O C Anumba
Changes in vaginal microbiota that is associated with preterm birth (PTB) leave specific metabolite fingerprints that can be detected in the cervicovaginal fluid (CVF) using metabolomics techniques. In this study, we characterize and validate the CVF metabolite profile of pregnant women presenting with symptoms of threatened preterm labor (PTL) by both (1)H-nuclear magnetic resonance spectroscopy (NMR) and enzyme-based spectrophotometry. We also determine their predictive capacity for PTB, singly, and in combination, with current clinical screening tools - cervicovaginal fetal fibronectin (FFN) and ultrasound cervical length (CL)...
2016: Frontiers in Medicine
Tomasz Mroczek, Tomasz Plech, Monika Wujec
Till now, three major spectroscopic techniques, fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, have been used for determination of thiol-thione tautomeric forms. Therefore, a novel analytical concept of discrimination of 1,2,4-triazole-3-thione and 3-thiol tautomers using two high-resolution mass spectrometers has been proposed. It comprises the high-performance liquid chromatography (HPLC) hyphenated with electrospray ionization (ESI)-time-of-flight mass spectrometry (ESI-TOF-MS, positive ion mode) followed by in-source collision-induced dissociation (CID) and low-energy CID-tandem mass spectrometry (MS/MS) analysis measured with a Quadruple-TOF-MS instrument...
October 24, 2016: Journal of Chromatographic Science
William A Cantara, Erik D Olson, Karin Musier-Forsyth
In addition to their role in correctly attaching specific amino acids to cognate tRNAs, aminoacyl-tRNA synthetases (aaRS) have been found to possess many alternative functions and often bind to and act on other nucleic acids. In contrast to the well-defined 3D structure of tRNA, the structures of many of the other RNAs recognized by aaRSs have not been solved. Despite advances in the use of X-ray crystallography (XRC), nuclear magnetic resonance (NMR) spectroscopy and cryo-electron microscopy (cryo-EM) for structural characterization of biomolecules, significant challenges to solving RNA structures still exist...
October 21, 2016: Methods: a Companion to Methods in Enzymology
Nial J Wheate, Kristie-Ann Dickson, Ryung Rae Kim, Alireza Nematollahi, René B Macquart, Veysel Kayser, Guocan Yu, W Bret Church, Deborah J Marsh
Pillar[n]arenes are a new family of nanocapsules that have shown application in a number of areas, but because of their poor water solubility their biomedical applications are limited. Recently, a method of synthesizing water-soluble pillar[n]arenes was developed. In this study, carboxylated pillar[n]arenes (WP[n], n = 6 or 7) have been examined for their ability to form host-guest complexes with compounds relevant to drug delivery and biodiagnostic applications. Both pillar[n]arenes form host-guest complexes with memantine, chlorhexidine hydrochloride, and proflavine by (1)H nuclear magnetic resonance and modeling...
October 21, 2016: Journal of Pharmaceutical Sciences
Jari E Kaikkonen, Peter Würtz, Emmi Suomela, Miia Lehtovirta, Antti J Kangas, Antti Jula, Vera Mikkilä, Jorma S A Viikari, Markus Juonala, Tapani Rönnemaa, Nina Hutri-Kähönen, Mika Kähönen, Terho Lehtimäki, Pasi Soininen, Mika Ala-Korpela, Olli T Raitakari
: Non-alcoholic fatty liver is associated with obesity-related metabolic disturbances, but little is known about the metabolic perturbations preceding fatty liver disease. We performed comprehensive metabolic profiling to assess how circulating metabolites, such as lipoprotein lipids, fatty acids, amino acids and glycolysis-related metabolites, reflect the presence of and future risk for fatty liver in young adults. Sixty-eight lipids and metabolites were quantified by nuclear magnetic resonance metabolomics in the population-based Young Finns Study from serum collected in 2001 (n=1,575), 2007 (n=1,509) and 2011 (n=2,002)...
October 24, 2016: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
Yiqiong Pu, Xitong Zhang, Qi Zhang, Bing Wang, Yuxi Chen, Chuanqi Zang, Yuqin Wang, Tina Ting-Xia Dong, Tong Zhang
20(S)-Protopanaxadiol (PPD), a bioactive compound extracted from ginseng, possesses cardioprotective, neuroprotective, anti-inflammatory, antiestrogenic, anticancer and anxiolytic effects. However, the clinical application of PPD is limited by its weak aqueous solubility. In this study, we optimized an efficient method of preparing its phospholipid complex (PPD-PLC) using a central composite design and response surface analysis. The prepared PPD-PLC was characterized by differential scanning calorimetric, powder X-ray diffraction, Fourier-transformed infrared spectroscopy and nuclear magnetic resonance analyses associated with molecular docking calculation...
October 19, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Eisuke Chikayama, Ryo Yamashina, Keiko Komatsu, Yuuri Tsuboi, Kenji Sakata, Jun Kikuchi, Yasuyo Sekiyama
Foods from agriculture and fishery products are processed using various technologies. Molecular mixture analysis during food processing has the potential to help us understand the molecular mechanisms involved, thus enabling better cooking of the analyzed foods. To date, there has been no web-based tool focusing on accumulating Nuclear Magnetic Resonance (NMR) spectra from various types of food processing. Therefore, we have developed a novel web-based tool, FoodPro, that includes a food NMR spectrum database and computes covariance and correlation spectra to tasting and hardness...
October 19, 2016: Metabolites
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