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https://www.readbyqxmd.com/read/28226419/evaluation-of-risk-factors-for-clostridium-difficile-infection-in-hematopoietic-stem-cell-transplant-recipients
#1
Tonya L Scardina, Elena Kang Martinez, Neelam Balasubramanian, Mary Fox-Geiman, Scott E Smith, Jorge P Parada
STUDY OBJECTIVES: The primary objective was to determine the impact of hematologic malignancies and/or conditioning regimens on the risk of developing Clostridium difficile infection (CDI) in patients undergoing hematopoietic stem cell transplantation (HSCT). Secondary objectives were to determine if traditional CDI risk factors applied to patients undergoing HSCT and to determine the presence of CDI markers of severity of illness among this patient population. DESIGN: Single-center, retrospective, case-control study...
February 22, 2017: Pharmacotherapy
https://www.readbyqxmd.com/read/28226220/water-oxidation-mechanisms-of-metal-oxide-catalysts-by-vibrational-spectroscopy-of-transient-intermediates
#2
Miao Zhang, Heinz Frei
Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements...
February 22, 2017: Annual Review of Physical Chemistry
https://www.readbyqxmd.com/read/28226213/an-oscillatory-reaction-induced-periodic-c-quadruplex-dna-gating-of-artificial-ion-channels
#3
Jian Wang, Ruochen Fang, Jue Hou, Huacheng Zhang, Ye Tian, Huanting Wang, Lei Jiang
Many biological ion channels controlled by biochemical reactions have autonomous and periodic gating functions, which play important roles in continuous mass transport and signal transmission of living systems. Inspired by these functional biological ion channel systems, here we report an artificial self-oscillating nanochannel system that can autonomously and periodically control its gating process under constant conditions. The system is constructed by integrating a chemical oscillator, consisting of BrO3-, Fe(CN)64-, H+, and SO32-, into a synthetic proton-sensitive nanochannel modified with C-quadruplex (C4) DNA motors...
February 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28225622/how-the-coordinated-structures-of-ag-i-catalysts-affect-the-outcomes-of-carbon-dioxide-incorporation-into-propargylic-amine-a-dft-study
#4
Ruming Yuan, Baohuan Wei, Gang Fu
Density functional theory calculations have been carried out to explore the detailed mechanisms for carbon dioxide incorporation of N-unsubstituted propargylic amine catalyzed by Ag(I) catalysts. We show that the reaction undergoes substrate adsorption or displacement, isomerization from amine-coordinated species to the alkyne-coordinated species, CO2 attack and proton transfer, giving the carbamate intermediate. Subsequently, the reaction would bifurcate at the intermolecular ring closing step, which produces five-membered ring (5MR) and six-membered ring (6MR) products at the same time, thus raising a regioselectivity issue...
February 22, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28225613/dehydrogenation-free-energy-of-co-2-aq-from-density-functional-theory-based-molecular-dynamics
#5
Florian H Hodel, Sandra Luber
Electron and proton transfers are important steps occurring in nature and in artificial (catalytic) reaction mechanisms. The often employed approach of calculating the energy differences of those steps using methods involving geometry optimizations neglects the influence of dynamic effects such as solvent rearrangement. To further investigate this issue and inspired by recent research in water oxidation, we calculate in the present study the dehydrogenation free energy of aqueous Co(2+), which is the free energy change associated with the first step of the reaction mechanism of model Co(II)-based water oxidation catalysts...
February 22, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28225609/regulation-and-plasticity-of-catalysis-in-enzymes-insights-from-analysis-of-mechanochemical-coupling-in-myosin
#6
Xiya Lu, Victor Ovchinnikov, Darren Demapan, Daniel Roston, Qiang Cui
The mechanism of ATP hydrolysis in the myosin motor domain is analyzed using a combination of DFTB3/CHARMM simulations and enhanced sampling techniques. The motor domain is modeled in the pre-powerstroke state, in the post-rigor state, and a hybrid model based on the post-rigor state with a closed nucleotide-binding pocket. The ATP hydrolysis activity is found to depend on the positioning of nearby water molecules, and a network of polar residues facilitates proton transfer and charge redistribution during hydrolysis...
February 22, 2017: Biochemistry
https://www.readbyqxmd.com/read/28225576/3d-multiecho-dixon-for-the-evaluation-of-hepatic-iron-and-fat-in-a-clinical-setting
#7
Benjamin Henninger, Heinz Zoller, Stephan Kannengiesser, Xiaodong Zhong, Werner Jaschke, Christian Kremser
PURPOSE: To prospectively evaluate a new 3D-multiecho-Dixon (3D-ME-Dixon) sequence for the quantification of hepatic iron and fat in a clinical setting. MATERIALS AND METHODS: In all, 120 patients underwent 1.5T magnetic resonance imaging of the liver between December 2013 and June 2015 including the following three sequences: 3D-ME-Dixon with inline calculation of R2* and proton-density fat-fraction (PDFF) maps, single-voxel-spectroscopy (SVS), 2D multigradient-echo sequence (2D-ME-GRE)...
February 22, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28225569/hepatic-alanine-differentiates-nonalcoholic-steatohepatitis-from-simple-steatosis-in-humans-and-mice-a-proton-mr-spectroscopy-study-with-long-echo-time
#8
Tae-Hoon Kim, Hong Young Jun, Ki-Jong Kim, Young Hwan Lee, Myeung Su Lee, Keum Ha Choi, Ki Jung Yun, Yong Yeon Jeong, Chung Hwan Jun, Eun Young Cho, Kwon-Ha Yoon
PURPOSE: To evaluate the hepatic metabolic alterations in nonalcoholic fatty liver disease (NAFLD) by using (1) H-MRS (proton magnetic resonance spectroscopy) with long echo time and to test the reproducibility of human study in an animal model. Liver biopsy is the gold standard for diagnosing NAFLD but with practical constraints. (1) H-MRS allows in vivo assessment of hepatocellular metabolism and has shown potential for biochemical differentiation in diffuse liver disease. MATERIALS AND METHODS: In all, 32 subjects (11 patients with nonalcoholic steatohepatitis [NASH], 15 with simple steatosis [SS], and six healthy controls) were studied...
February 22, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28225357/robust-sound-speed-estimation-for-ultrasound-based-hepatic-steatosis-assessment
#9
Imbault Marion, Alex Faccinetto, Bruno-Felix Osmanski, Antoine Tissier, Thomas Deffieux, Jean-Luc Gennisson, Valerie Vilgrain, Mickael Tanter
Hepatic steatosis is a common condition, the prevalence of which is increasing along with non-alcoholic fatty liver disease (NAFLD). Currently, the most accurate noninvasive imaging method for diagnosing and quantifying hepatic steatosis is MRI, which estimates the Proton-Density Fat Fraction (PDFF) as a measure of fractional fat content. However, MRI suffers several limitations including cost, contra-indications and poor availability. Although conventional ultrasound is widely used by radiologists for hepatic steatosis assessment, it remains qualitative and operator dependent...
February 22, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28225090/proton-transfer-dynamics-dictate-quinone-speciation-at-lipid-modified-electrodes
#10
Edmund C M Tse, Christopher J Barile, Ying Li, Steven C Zimmerman, Ali Hosseini, Andrew A Gewirth
Proton-coupled electron transfer (PCET) reactions are ubiquitous in biochemistry and alternative energy schemes. Natural enzymes utilize quinones in proton transfer chains and energy conversion processes. Here, we utilize a bio-inspired hybrid bilayer membrane system to control the reaction mechanism of a quinone molecule covalently bound to an electrode surface. In particular, by impeding proton access to the quinone moiety, we change the reaction pathway from a PCET process to a pure electron transfer step...
February 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28224986/mass-spectrometric-monitoring-of-interfacial-photoelectron-transfer-and-imaging-of-active-crystalline-facets-of-semiconductors
#11
Hongying Zhong, Juan Zhang, Xuemei Tang, Wenyang Zhang, Ruowei Jiang, Rui Li, Disong Chen, Peng Wang, Zhiwei Yuan
Monitoring of interfacial electron transfer (ET) in situ is important to understand the ET mechanism and designing efficient photocatalysts. We describe herein a mass spectrometric approach to investigate the ultrafast transfer of photoelectrons that are generated by ultraviolet irradiation on surfaces of semiconductor nanoparticles or crystalline facets. The mass spectrometric approach can not only untargetedly detect various intermediates but also monitor their reactivity through associative or dissociative photoelectron capture dissociation, as well as electron detachment dissociation of adsorbed molecules...
February 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/28224790/ph-dependent-photodeprotection-of-formaldehyde-homolytic-c-c-scission-in-acidic-aqueous-solution-versus-heterolytic-c-c-scission-in-basic-aqueous-solution
#12
Mingyue Liu, Wenjian Tang, Ming-De Li, David Lee Phillips
The photodeprotection of formaldehyde was investigated for 3-(1-hydroxypropan-2-yl)benzophenone (3-HPBP) with ultrafast time-resolved spectroscopy. The femtosecond transient absorption results indicated the singlet excited state of 3-HPBP transformed efficiently into its triplet state by a fast intersystem crossing. In acidic (pH=0) and basic (pH=12.5) aqueous solutions, the triplet intermediate was a key precursor for the deprotection of formaldehyde via two different pathways. However little photodeprotection was observed in neutral (pH=7) aqueous solution where the triplet intermediate appeared to undergo a proton coupled electron transfer process to form a ketyl radical transient...
February 22, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28224394/native-like-and-denatured-cytochrome-c-ions-yield-cation-to-anion-proton-transfer-reaction-products-with-similar-collision-cross-sections
#13
Kenneth J Laszlo, John H Buckner, Eleanor B Munger, Matthew F Bush
The relationship between structures of protein ions, their charge states, and their original structures prior to ionization remains challenging to decouple. Here, we use cation-to-anion proton transfer reactions (CAPTR) to reduce the charge states of cytochrome c ions in the gas phase, and ion mobility to probe their structures. Ions were formed using a new temperature-controlled nanoelectrospray ionization source at 25 °C. Characterization of this source demonstrates that the temperature of the liquid sample is decoupled from that of the atmospheric pressure interface, which is heated during CAPTR experiments...
February 21, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28224302/retinal-cavernous-haemangioma-treated-by-proton-beam-therapy
#14
Amir Mahdjoubi, Rémi Dendale, Livia Lumbroso-Le Rouic, Laurence Desjardins, Nathalie Cassoux
As one of intraocular tumours, retinal cavernous haemangioma is a benign vascular lesion that is mostly unilateral. Very few cases about cavernous haemangioma treatment are reported, and there is currently no consensus on the most effective treatment. This clinical case reports on a 40-year-old male, presenting a peripheral retinal cavernous haemangioma, complicated with a repetitive vitreous haemorrhage causing bad vision. Several therapeutic methods were unsuccessfully attempted to stop haemorrhagic recurrences...
February 21, 2017: International Ophthalmology
https://www.readbyqxmd.com/read/28223800/comparison-of-the-cellular-transport-mechanism-of-cationic-star-shaped-polymers-and-liposomes-in-hacat-cells
#15
Heng-Cong Luo, Na Li, Li Yan, Kai-Jin Mai, Kan Sun, Wei Wang, Guo-Juan Lao, Chuan Yang, Li-Ming Zhang, Meng Ren
Several biological barriers must be overcome to achieve efficient nonviral gene delivery. These barriers include target cell uptake, lysosomal degradation, and dissociation from the carrier. In this study, we compared the differences in the uptake mechanism of cationic, star-shaped polymer/MMP-9siRNA complexes (β-CD-(D3)7/MMP-9siRNA complexes: polyplexes) and commercial liposome/MMP-9siRNA complexes (Lipofectamine(®) 2000/MMP-9siRNA complexes: liposomes). The uptake pathway and transfection efficiency of the polyplexes and liposomes were determined by fluorescence microscopy, flow cytometry, and reverse transcriptase-polymerase chain reaction...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28223391/evaluation-of-para-aminosalicylic-acid-pas-as-a-substrate-of-multiple-solute-carrier-slc-uptake-transporters-and-possible-drug-interactions-with-nsaids-in-vitro
#16
Md Masud Parvez, Ho Jung Shin, Jin Ah Jung, Jae-Gook Shin
para-Aminosalicylic acid (PAS) is a second-line anti-tuberculosis drug used to treat multidrug-resistant and extensively drug-resistant tuberculosis for more than 60 years. Renal secretion and glomerular filtration are the major pathways for elimination of PAS. We comprehensively studied PAS transport by using cell lines that overexpressed various transporters, and found that PAS acts as a novel substrate of organic anionic polypeptide (OATP1B1), organic cationic transporters (OCT1 and OCT2), and organic anion transporters (OAT1 and OAT3) but not a substrate of any ATP-binding cassette (ABC) transporters...
February 21, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28223285/butyrate-regulates-liver-mitochondrial-function-efficiency-and-dynamic-in-insulin-resistant-obese-mice
#17
Maria Pina Mollica, Giuseppina Mattace Raso, Gina Cavaliere, Giovanna Trinchese, Chiara De Filippo, Serena Aceto, Marina Prisco, Claudio Pirozzi, Francesca Di Guida, Adriano Lama, Marianna Crispino, Diana Tronino, Paola Di Vaio, Roberto Berni Canani, Antonio Calignano, Rosaria Meli
Fatty liver, oxidative stress, and mitochondrial dysfunction are key pathophysiological features of insulin resistance and obesity. Butyrate, produced by fermentation in the large intestine by gut microbiota, and its synthetic derivative, the N-(1-carbamoyl-2-phenyl-ethyl) butyramide, FBA, have been demonstrated to be protective against insulin resistance and fatty liver.Here, hepatic mitochondria were identified as the main target of the beneficial effect of both butyrate-based compounds in reverting insulin resistance and fat accumulation in diet induced obese mice...
February 21, 2017: Diabetes
https://www.readbyqxmd.com/read/28223087/do-sleeve-gastrectomy-and-gastric-bypass-influence-treatment-with-proton-pump-inhibitors-4-years-after-surgery-a-nationwide-cohort
#18
Jérémie Thereaux, Thomas Lesuffleur, Sébastien Czernichow, Arnaud Basdevant, Simon Msika, David Nocca, Bertrand Millat, Anne Fagot-Campagna
BACKGROUND: Gastroesophageal reflux disease (GERD) is a common obesity-related co-morbidity that routinely is treated by continuous proton pump inhibitor (PPI) therapy. A number of concerns have been raised regarding the risk of de novo GERD or exacerbation of preexisting GERD after sleeve gastrectomy (SG). OBJECTIVE: To assess PPI use at 4 years after bariatric surgery. SETTING: French National Health Insurance. METHODS: Data were extracted from the French National Health Insurance database...
December 23, 2016: Surgery for Obesity and related Diseases: Official Journal of the American Society for Bariatric Surgery
https://www.readbyqxmd.com/read/28223076/leaching-of-rare-earth-elements-from-fluorescent-powder-using-the-tea-fungus-kombucha
#19
Stefanie Hopfe, Katrin Flemming, Falk Lehmann, Robert Möckel, Sabine Kutschke, Katrin Pollmann
In most modern technologies such as flat screens, highly effective magnets and lasers, as well as luminescence phosphors, Rare Earth Elements (REE) are used. Unfortunately no environmentally friendly recycling process exists so far. In comparison to other elements the interaction of microorganisms with REE has been studied to a less extent. However, as REE are ubiquitously present in nature it can be assumed that microorganisms play an important role in the biogeochemistry of REE. This study investigates the potential of organic acid-producing microbes for extracting REE from industrial waste...
February 17, 2017: Waste Management
https://www.readbyqxmd.com/read/28222679/comparative-mitogenomics-indicates-respiratory-competence-in%C3%A2-parasitic-viscum-despite%C3%A2-loss-of-complex-i%C3%A2-and-extreme-sequence%C3%A2-divergence-and-reveals-horizontal-gene-transfer-and-remarkable%C3%A2-variation-in-genome-size
#20
Elizabeth Skippington, Todd J Barkman, Danny W Rice, Jeffrey D Palmer
BACKGROUND: Aerobically respiring eukaryotes usually contain four respiratory-chain complexes (complexes I-IV) and an ATP synthase (complex V). In several lineages of aerobic microbial eukaryotes, complex I has been lost, with an alternative, nuclear-encoded NADH dehydrogenase shown in certain cases to bypass complex I and oxidize NADH without proton translocation. The first loss of complex I in any multicellular eukaryote was recently reported in two studies; one sequenced the complete mitogenome of the hemiparasitic aerial mistletoe, Viscum scurruloideum, and the other sequenced the V...
February 21, 2017: BMC Plant Biology
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