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Magnetic resonance spectroscopy

Michael K Yeung, Sophia L Sze, Jean Woo, Timothy Kwok, David H K Shum, Ruby Yu, Agnes S Chan
BACKGROUND: Some functional magnetic resonance imaging studies have reported altered activations in the frontal cortex during working memory (WM) performance in individuals with mild cognitive impairment (MCI), but the findings have been mixed. The objective of the present study was to utilize near-infrared spectroscopy (NIRS), an alternative imaging technique, to examine neural processing during WM performance in individuals with MCI. METHODS: Twenty-six older adults with MCI (7 males; mean age 69...
October 27, 2016: Dementia and Geriatric Cognitive Disorders
Amélie Juhin, Philippe Sainctavit, Katharina Ollefs, Marcin Sikora, Adriano Filipponi, Pieter Glatzel, Fabrice Wilhelm, Andrei Rogalev
X-ray magnetic circular dichroism is measured at the Fe K pre-edge in yttrium iron garnet using two different procedures that allow reducing the intrinsic broadening due to the 1s corehole lifetime. First, deconvolution of XMCD data measured in total fluorescence yield (TFY) with an extremely high signal-to-noise ratio enables a factor of 2.4 to be gained in the XMCD intensity. Ligand field multiplet calculations performed with different values of intrinsic broadening show that deconvolving such high quality XMCD data is similar to reducing the lifetime broadening from a 1s corehole to a 2p corehole...
October 26, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
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
Christiane Stern, Laurent Castera
Non-invasive diagnosis and quantification of hepatic steatosis rely on two different but complementary approaches: biomarkers or imaging techniques, either ultrasound-based such as liver ultrasonography and controlled attenuation parameter (CAP), or computed tomography (CT) and magnetic resonance imaging (MRI). Scores for the detection of steatosis have not gained much popularity in clinical practice so far. CAP, using the M probe, is the most promising technique but needs to be implemented with the XL probe and compared to ultrasound that, despite its limitations, remains the most widely used method...
October 25, 2016: Hepatology International
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
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
Monika Cichocka, Justyna Kozub, Paulina Karcz, Andrzej Urbanik
BACKGROUND: The aim of this (1)HMRS study was to identify any potential regional differences in the metabolic spectrum in the brains of healthy children. MATERIAL/METHODS: Forty-nine healthy children aged 6-15 years (mean 11.6 years) were examined, including 21 girls and 28 boys. A 1.5T MR system (xi Signa HD 1.5T General Electric) was used in patient examinations. The VOI (Volume of Interest) was defined in 7 locations: the frontal lobe in the right and left hemispheres, the basal ganglia in the right and left hemispheres, hippocampus in the right and left hemispheres and cerebellum...
2016: Polish Journal of Radiology
Maxim Ziatdinov, Artem Maksov, Li Li, Athena S Sefat, Petro Maksymovych, Sergei V Kalinin
Electronic interactions present in material compositions close to the superconducting dome play a key role in the manifestation of high-T c superconductivity. In many correlated electron systems, however, the parent or underdoped states exhibit strongly inhomogeneous electronic landscape at the nanoscale that may be associated with competing, coexisting, or intertwined chemical disorder, strain, magnetic, and structural order parameters. Here we demonstrate an approach based on a combination of scanning tunneling microscopy/spectroscopy and advanced statistical learning for an automatic separation and extraction of statistically significant electronic behaviors in the spin density wave regime of a lightly (∼1%) gold-doped BaFe2As2...
November 25, 2016: Nanotechnology
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
Liam F Fitzgerald, Anita D Christie, Jane A Kent
Despite intensive efforts to understand the extent to which skeletal muscle mitochondrial capacity changes in older humans, the answer to this important question remains unclear. To determine what the preponderance of evidence from in vivo studies suggests, we conducted a systematic review and meta-analysis of the effects of age on muscle oxidative capacity as measured noninvasively by magnetic resonance spectroscopy. A secondary aim was to examine potential moderators contributing to differences in results across studies, including muscle group, physical activity status, and sex...
July 18, 2016: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Kavita Singh, Richa Trivedi, Seenu Haridas, Kailash Manda, Subash Khushu
Mild traumatic brain injury (mTBI) is the most common form of TBI (70-90%) with consequences of anxiety-like behavioral alterations in approximately 23% of mTBI cases. This study aimed to assess whether mTBI-induced anxiety-like behavior is a consequence of neurometabolic alterations. mTBI was induced using a weight drop model to simulate mild human brain injury in rodents. Based on injury induction and dosage of anesthesia, four animal groups were included in this study: (i) injury with anesthesia (IA); (ii) sham1 (injury only, IO); (iii) sham2 (only anesthesia, OA); and (iv) control rats...
October 25, 2016: NMR in Biomedicine
R J Willcocks, W T Triplett, S C Forbes, H Arora, C R Senesac, D J Lott, T R Nicholson, W D Rooney, G A Walter, K Vandenborne
There is a pressing need for biomarkers and outcomes that can be used across disease stages in Duchenne muscular dystrophy (DMD), to facilitate the inclusion of a wider range of participants in clinical trials and to improve our understanding of the natural history of DMD. Quantitative magnetic resonance imaging (qMRI) and spectroscopy (MRS) biomarkers show considerable promise in both the legs and forearms of individuals with DMD, but have not yet been examined in functionally important proximal upper extremity muscles such as the biceps brachii and deltoid...
October 24, 2016: Journal of Neurology
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
Shelley E Keating, Helen M Parker, Toby G Pavey, Michael K Baker, Ian D Caterson, Jacob George, Nathan A Johnson
Objective. Epidemiologic studies suggest an inverse relationship between nonalcoholic fatty liver disease (NAFLD), visceral adipose tissue (VAT), and self-reported physical activity levels. However, subjective measurements can be inaccurate and prone to reporter bias. We investigated whether objectively quantified physical activity levels predicted liver fat and VAT in overweight/obese adults. Methods. Habitual physical activity was measured by triaxial accelerometry for four days (n = 82). Time spent in sedentary behavior (MET < 1...
2016: Journal of Obesity
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
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
Akio Hayashi, Hiromi Ota, Xavier López, Norihito Hiyoshi, Nao Tsunoji, Tsuneji Sano, Masahiro Sadakane
Dipotassium cation (K(+))-encapsulated Preyssler-type phosphotungstate, [P5W30O110K2](13-), was prepared by heating monobismuth (Bi(3+))-encapsulated Preyssler-type phosphotungstate, [P5W30O110Bi(H2O)](12-), in acetate buffer in the presence of an excess amount of potassium cations. Characterization of the isolated potassium salt, K13[P5W30O110K2] (1a), and its acid form, H13[P5W30O110K2] (1b), by single crystal X-ray structure analysis, (31)P and (183)W nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV), high-resolution electrospray ionization mass spectroscopy (HR-ESI-MS), and elemental analysis revealed that two potassium cations are encapsulated in the Preyssler-type phosphotungstate molecule with formal D5h symmetry, which is the first example of a Preyssler-type compound with two encapsulated cations...
October 24, 2016: Inorganic Chemistry
Giovanni Rizzo, Stefano Zanigni, Roberto De Blasi, Daniela Grasso, Davide Martino, Rodolfo Savica, Giancarlo Logroscino
Brain magnetic resonance (MR) represents a useful and feasible tool for the differential diagnosis of Parkinson's disease. Conventional MR may reveal secondary forms of parkinsonism and may show peculiar brain alterations of atypical parkinsonian syndromes. Furthermore, advanced MR techniques, such as morphometric-volumetric analyses, diffusion-weighted imaging, diffusion tensor imaging, tractography, proton MR spectroscopy, and iron-content sensitive imaging, have been used to obtain quantitative parameters useful to increase the diagnostic accuracy...
2016: Parkinson's Disease
Zi Long, Meiying Liu, Ruming Jiang, Guangjiang Zeng, Qing Wan, Hongye Huang, Fengjie Deng, Yiqun Wan, Xiaoyong Zhang, Yen Wei
Aggregation-induced emission (AIE)-active fluorescent organic nanoparticles (FNPs) have been extensively explored for fluorescence "turn-on" bio-imaging applications with the unique advantages over conventional FNPs. Transformation of AIE-active molecules into FNPs can greatly expand their biomedical application potential. Here we reported a novel "one-pot" strategy for fabricating AIE-active FNPs through an ultrasonic-assisted, catalysts-free and solvent-free Kabachnik-Fields (KF) reaction for the first time...
October 11, 2016: Ultrasonics Sonochemistry
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