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https://www.readbyqxmd.com/read/28323929/human-brown-adipose-tissue-temperature-and-fat-fraction-are-related-to-its-metabolic-activity
#1
Kalle Koskensalo, Juho Raiko, Teemu Saari, Virva Saunavaara, Olli Eskola, Pirjo Nuutila, Jani Saunavaara, Riitta Parkkola, Kirsi A Virtanen
Background and aim: The metabolic activity of human brown adipose tissue (BAT) has been previously examined using positron-emission-tomography (PET). The aim of this study was to use proton Magnetic Resonance Spectroscopy (1H MRS) to investigate whether the temperature and the fat fraction (FF) of brown and white adipose tissue (WAT) are associated with BAT metabolic activity determined by 18F-FDG-PET. Materials and methods: Ten healthy subjects (4f/6m, 25-45 y) were studied using PET-MRI during acute cold exposure and at ambient room temperature...
February 21, 2017: Journal of Clinical Endocrinology and Metabolism
https://www.readbyqxmd.com/read/28323637/accelerated-monte-carlo-simulation-on-the-chemical-stage-in-water-radiolysis-using-gpu
#2
Zhen Tian, Steve B Jiang, Xun Jia
The accurate simulation of water radiolysis is an important step to understand the mechanisms of radiobiology and quantitatively test some hypotheses regarding radiobiological effects. However, the simulation of water radiolysis is highly time consuming, taking hours or even days to be completed by a conventional CPU processor. This time limitation hinders cell-level simulations for a number of research studies. We recently initiated efforts to develop gMicroMC, a GPU-based fast microscopic MC simulation package for water radiolysis...
March 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28323552/helicobacter-pylori-eradication-in-the-swedish-population
#3
Eva Doorakkers, Jesper Lagergren, Vijaya Krishna Gajulapuri, Steven Callens, Lars Engstrand, Nele Brusselaers
OBJECTIVES: Helicobacter pylori is associated with peptic ulcers and gastric cancer and its eradication aims to prevent these conditions. The recommended eradication regimen is triple therapy, consisting of a proton-pump inhibitor in combination with clarithromycin and amoxicillin or metronidazole for 7 days. Yet, other antibiotic regimens are sometimes prescribed. We aimed to assess the use of eradication therapy for H. pylori in the Swedish population during the last decade. MATERIALS AND METHODS: This population-based study used data from the Swedish Prescribed Drug Register...
March 21, 2017: Scandinavian Journal of Gastroenterology
https://www.readbyqxmd.com/read/28323432/electronic-structures-and-oh-induced-atmospheric-degradation-of-cf3nsf2-a-potential-green-dielectric-replacement-for-sf6
#4
Lin Cheng, Xiaojuan Yu, Kun Zhao, Hua Hou, Baoshan Wang
Electronic structures of Trifluoromethyl imionosulfur difluoride (CF3NSF2) and degradation mechanisms by hydroxyl radical have been investigated using density functional theory (M06-2X), the complete basis set quadratic CBS-Q, and the explicitly correlated coupled-cluster methods [CCSD(T)-F12]. The d-function augmented Correlation-consistent basis sets including triple- and quadruple- were employed for the sulfur-containing species. It was found that CF3NSF2 exists as two conformations connected by the internal rotation of CF3 around the central NS bond...
March 21, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28323405/oxygen-vacancy-enables-markedly-enhanced-magnetic-resonance-imaging-guided-photothermal-therapy-of-a-gd3-doped-contrast-agent
#5
Dalong Ni, Jiawen Zhang, Jing Wang, Ping Hu, Yingying Jin, Zhongmin Tang, Zhenwei Yao, Wenbo Bu, Jianlin Shi
The Gd3+-based contrast agents (CAs) are the most prevailing and widely used for enhanced magnetic resonance imaging (MRI). Numbers of approaches have been developed to regulate the key parameters in order to obtain high-relaxivity CAs, according to the classic Solomon-Bloembergen-Morgen theory. Herein, a method of controlling oxygen vacancies in inorganic nanosized CAs has been developed for largely accelerated proton relaxation to obtain a high r1 value. Such a strategy is verified on oxygen-deficient PEG-NaxGdWO3 nanorods, which exhibit remarkable r1 value up to 80 mM-1s-1 (at 0...
March 21, 2017: ACS Nano
https://www.readbyqxmd.com/read/28320077/marginal-ulcers-after-one-anastomosis-mini-gastric-bypass-a-survey-of-surgeons
#6
K K Mahawar, A N Reed, Y N H Graham
Many surgeons believe that one anastomosis (mini) gastric bypass (OAGB/MGB) is associated with a high marginal ulcer (MU) rate and that this is associated with complications in a significant number of patients. The purpose of this survey was to find out the participant-reported incidence of MU after OAGB/MGB and its complications. We also aimed to understand practices in this cohort concerning prophylaxis, diagnosis, treatment and management of complications. Bariatric surgeons who perform OAGB/MGB procedures were invited to participate in a confidential, online survey using SurveyMonkey®...
March 20, 2017: Clinical Obesity
https://www.readbyqxmd.com/read/28319664/reduction-of-folate-by-dihydrofolate-reductase-from-thermotoga-maritima
#7
E Joel Loveridge, Lukas Hroch, Robert L Hughes, Thomas Williams, Rhidian L Davies, Antonio Angelastro, Louis Y P Luk, Giovanni Maglia, Rudolf K Allemann
Mammalian dihydrofolate reductases (DHFR) catalyse the reduction of folate more efficiently than the equivalent bacterial enzymes, despite typically having similar efficiencies for the reduction of their natural substrate dihydrofolate. In contrast, we show here that DHFR from the hyperthermophilic bacterium Thermotoga maritima is able to catalyse reduction of folate to tetrahydrofolate with a similar efficiency to reduction of dihydrofolate under saturating conditions. NMR and mass spectrometry experiments showed no evidence for production of free dihydrofolate during either the EcDHFR- or TmDHFR-catalysed reductions of folate, suggesting that both enzymes perform the two reduction steps without release of the partially reduced substrate...
March 20, 2017: Biochemistry
https://www.readbyqxmd.com/read/28319378/computational-study-of-13c-nmr-csa-patterns-in-c20h10-and-c20h10-4-insights-into-their-variation-upon-planarization-and-formation-of-concentric-aromatic-species-in-the-smaller-isolated-pentagon-structural-motif
#8
Alvaro Muñoz-Castro, Wilson Caimanque-Aguilar, Cesar Morales-Verdejo
Corannulene, C20H10, exhibits a concave surface in the ground state which is able to experience a bowl-to-bowl inversion through a planar conformation. Such structure is the smaller example resembling an isolated-pentagon motif, as a relevant fragment in Fullerene chemistry. Here, we explored the differences between bowl and planar conformations involving both energetic and 13C-NMR properties, for the neutral and tetraanionic species by using DFT methods. This allows to understand the variation of the chemical environment at the carbon atoms upon planarization of this representive motif...
March 20, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28319377/mechanism-and-origins-of-stereoselectivity-in-the-cinchona-thiourea-and-squaramide-catalyzed-asymmetric-michael-addition-of-nitroalkanes-to-enones
#9
Matthew N Grayson
We report density functional theory calculations which examine the mechanism and origins of stereoselectivity of Soós' landmark discovery from 2005 that cinchona thioureas catalyze the asymmetric Michael addition of nitroalkanes to enones. We show that the electrophile is activated by the catalyst's protonated amine and that the nucleophile binds to the thiourea moiety by hydrogen bonding. These results lead to the correction of published mechanistic work which did not consider this activation mode. We have also investigated the corresponding cinchona squaramide-catalyzed reaction and found that it proceeds by the same mechanism, despite the differences in the geometry of the two catalysts' hydrogen bond donating groups, which demonstrates the generality of this mechanistic model...
March 20, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28319179/biophysical-comparison-of-atp-driven-proton-pumping-mechanisms-suggests-a-kinetic-advantage-for-the-rotary-process-depending-on-coupling-ratio
#10
Ramu Anandakrishnan, Daniel M Zuckerman
ATP-driven proton pumps, which are critical to the operation of a cell, maintain cytosolic and organellar pH levels within a narrow functional range. These pumps employ two very different mechanisms: an elaborate rotary mechanism used by V-ATPase H+ pumps, and a simpler alternating access mechanism used by P-ATPase H+ pumps. Why are two different mechanisms used to perform the same function? Systematic analysis, without parameter fitting, of kinetic models of the rotary, alternating access and other possible mechanisms suggest that, when the ratio of protons transported per ATP hydrolyzed exceeds one, the one-at-a-time proton transport by the rotary mechanism is faster than other possible mechanisms across a wide range of driving conditions...
2017: PloS One
https://www.readbyqxmd.com/read/28319162/risk-of-acute-myocardial-infarction-in-patients-with-gastroesophageal-reflux-disease-a-nationwide-population-based-study
#11
Wei-Yi Lei, Jen-Hung Wang, Shu-Hui Wen, Chih-Hsun Yi, Jui-Sheng Hung, Tso-Tsai Liu, William C Orr, Chien-Lin Chen
OBJECTIVE: Gastroesophageal reflux disease (GERD) is a common disease which can cause troublesome symptoms and affect quality of life. In addition to esophageal complications, GERD may also be a risk factor for extra-esophageal complications. Both GERD and coronary artery disease (CAD) can cause chest pain and frequently co-exist. However, the association between GERD and acute myocardial infarction (AMI) remain unclear. The purpose of the study was to compare the incidence of acute myocardial infarction in GERD patients with an age-, gender-, and comorbidity matched population free of GERD...
2017: PloS One
https://www.readbyqxmd.com/read/28319031/evaluation-of-the-water-equivalence-of-plastic-materials-in-low-and-high-energy-clinical-proton-beams
#12
Ana Lourenco, David Shipley, Nigel Wellock, Russell Thomas, Hugo Bouchard, Andrzej Kacperek, Francesco Fracchiolla, Stefano Lorentini, Marco Schwarz, Niall MacDougall, Gary Royle, Hugo Palmans
The aim of this work was to evaluate the water-equivalence of new trial plastics designed specifically for light-ion beam dosimetry as well as commercially available plastics in clinical proton beams. The water-equivalence of materials was tested by computing a plastic-to-water conversion factor, <i>H</i><sub><i>pl</i>,w</sub>. Trial materials were characterized experimentally in 60 MeV and 226 MeV un-modulated proton beams and the results were compared with Monte Carlo simulations using the FLUKA code...
March 20, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28318906/analysis-of-molecular-mechanisms-of-atp-synthesis-from-the-standpoint-of-the-principle-of-electrical-neutrality
#13
REVIEW
Sunil Nath
Theories of biological energy coupling in oxidative phosphorylation (OX PHOS) and photophosphorylation (PHOTO PHOS) are reviewed and applied to ATP synthesis by an experimental system containing purified ATP synthase reconstituted into liposomes. The theories are critically evaluated from the standpoint of the principle of electrical neutrality. It is shown that the obligatory requirement to maintain overall electroneutrality of bulk aqueous phases imposes strong constraints on possible theories of energy coupling and molecular mechanisms of ATP synthesis...
March 8, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28318880/highly-conformal-craniospinal-radiotherapy-techniques-can-underdose-the-cranial-clinical-target-volume-if-leptomeningeal-extension-through-skull-base-exit-foramina-is-not-contoured
#14
D J Noble, T Ajithkumar, J Lambert, I Gleeson, M V Williams, S J Jefferies
AIMS: Craniospinal irradiation (CSI) remains a crucial treatment for patients with medulloblastoma. There is uncertainty about how to manage meningeal surfaces and cerebrospinal fluid (CSF) that follows cranial nerves exiting skull base foramina. The purpose of this study was to assess plan quality and dose coverage of posterior cranial fossa foramina with both photon and proton therapy. MATERIALS AND METHODS: We analysed the radiotherapy plans of seven patients treated with CSI for medulloblastoma and primitive neuro-ectodermal tumours and three with ependymoma (total n = 10)...
March 15, 2017: Clinical Oncology: a Journal of the Royal College of Radiologists
https://www.readbyqxmd.com/read/28318741/neonatal-magnetic-resonance-imaging-without-sedation-correlates-with-injury-severity-in-brachial-plexus-birth-palsy
#15
Andrea S Bauer, Peter Y Shen, Anna E Nidecker, Paul S Lee, Michelle A James
PURPOSE: Which infants with brachial plexus birth palsy (BPBP) should undergo microsurgical plexus reconstruction remains controversial. The current gold standard for the decision for plexus reconstruction is serial clinical examinations, but this approach obviates the possibility of early surgical treatment. We hypothesize that a new technique using 3-dimensional volumetric proton density magnetic resonance imaging (MRI) without sedation can evaluate the severity of BPBP injury earlier than serial clinical examinations...
March 16, 2017: Journal of Hand Surgery
https://www.readbyqxmd.com/read/28318318/non-guideline-recommended-prescribing-of-proton-pump-inhibitors-in-the-general-population
#16
Emma Mares-García, Antonio Palazón-Bru, Álvaro Martínez-Martín, David Manuel Folgado-de la Rosa, Avelino Pereira-Expósito, Vicente Francisco Gil-Guillén
OBJECTIVES: To determine the magnitude of non-guideline-recommended prescribing (NGRP) of proton pump inhibitors (PPIs) in the general population, its associated factors and expense. METHODS: We undertook a cross-sectional observational study in three community pharmacies in a Spanish region in 2013 involving a total of 302 patients with a prescription for PPIs. The main variable was the NGRP of PPIs. Secondary variables were: gender, age, antidepressants, osteoporosis, osteoarthritis, prescription cost per month and total number of chronic diseases...
March 20, 2017: Current Medical Research and Opinion
https://www.readbyqxmd.com/read/28318257/copper-i-catalyzed-enantioselective-addition-of-enynes-to-ketones
#17
Xiao-Feng Wei, Xiao-Wei Xie, Yohei Shimizu, Motomu Kanai
A copper(I)-catalyzed enantioselective addition of enynes to ketones was developed. The method allows facile construction of enantiomerically enriched tertiary alcohols using skipped enynes as stable hydrocarbon pronucleophiles. The combination of a soft copper(I)-conjugated Brønsted base catalyst with a chiral diphosphine ligand, (S,S)-Ph-BPE, enabled chemoselective deprotonation of the skipped enynes in the presence of ketones bearing intrinsically more acidic α-protons. The catalytically generated chiral allylcopper species enantio-, diastereo-, regio-, and chemoselectively reacted with ketones, thereby demonstrating excellent substrate generality with functional group tolerance...
March 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28318245/dinuclear-rhenium-complex-with-a-proton-responsive-ligand-as-a-redox-catalyst-for-the-electrochemical-co2-reduction
#18
Alexander Wilting, Thorsten Stolper, Ricardo A Mata, Inke Siewert
Herein, we present the reduction chemistry of a dinuclear α-diimine rhenium complex, 1, [Re2(L)(CO)6Cl2], with a proton responsive ligand and its application as a catalyst in the electrochemical CO2 reduction reaction (L = 4-tert-butyl-2,6-bis(6-(1H-imidazol-2-yl)-pyridin-2-yl)phenol). The complex has a phenol group in close proximity to the active center, which may act as a proton relay during catalysis, and pyridine-NH-imidazole units as α-diimine donors. The complex is an active catalyst for the electrochemical CO2 reduction reaction...
March 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28318128/proton-mr-spectroscopy-in-patients-with-nonlesional-insular-cortex-epilepsy-confirmed-by-invasive-eeg-recordings
#19
Yasmine Aitouche, Steve A Gibbs, Guillaume Gilbert, Olivier Boucher, Alain Bouthillier, Dang Khoa Nguyen
BACKGROUND AND PURPOSE: Recent studies suggest that a nonnegligible proportion of drug-resistant epilepsy surgery candidates have an epileptogenic zone that involves the insula. We aimed to examine the value of proton magnetic resonance spectroscopy ((1) H-MRS) in identifying patients with insular cortex epilepsy. METHODS: Patients with possible nonlesional drug-refractory insular epilepsy underwent a voxel-based (1) H-MRS study prior to an intracranial electroencephalographic (EEG) study...
March 20, 2017: Journal of Neuroimaging: Official Journal of the American Society of Neuroimaging
https://www.readbyqxmd.com/read/28318045/diagnosis-of-gastro-oesophageal-reflux-disease-is-enhanced-by-adding-oesophageal-histology-and-excluding-epigastric-pain
#20
N Vakil, M Vieth, B Wernersson, J Wissmar, J Dent
BACKGROUND: The diagnosis of gastro-oesophageal reflux disease (GERD) in clinical practice is limited by the sensitivity and specificity of symptoms and diagnostic testing. AIM: To determine if adding histology as a criterion and excluding patients with epigastric pain enhances the diagnosis for GERD. METHODS: Patients with frequent upper gastrointestinal symptoms who had not taken a proton pump inhibitor in the previous 2 months and who had evaluable distal oesophageal biopsies were included (Diamond study: NCT00291746)...
March 20, 2017: Alimentary Pharmacology & Therapeutics
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