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https://www.readbyqxmd.com/read/28650854/recent-developments-in-deuterium-oxide-tracer-approaches-to-measure-rates-of-substrate-turnover-implications-for-protein-lipid-and-nucleic-acid-research
#1
Matthew S Brook, Daniel J Wilkinson, Philip J Atherton, Ken Smith
PURPOSE OF REVIEW: Methods that inform on dynamic metabolism that can be applied to clinical populations to understand disease progression and responses to therapeutic interventions are of great importance. This review perspective will highlight recent advances, development, and applications of the multivalent stable isotope tracer deuterium oxide (D2O) to the study of substrate metabolism with particular reference to protein, lipids, and nucleic acids, and how these methods can be readily applied within clinical and pharmaceutical research...
June 24, 2017: Current Opinion in Clinical Nutrition and Metabolic Care
https://www.readbyqxmd.com/read/28649716/mechanism-of-microwave-assisted-pyrolysis-of-glucose-to-furfural-revealed-by-isotopic-tracer-and-quantum-chemical-calculations
#2
Liwei Bao, Lei Shi, Hu Luo, Lingzhao Kong, Shenggang Li, Wei Wei, Yuhan Sun
Glucose labelled with 13C or 18O was used to investigate the mechanism during its conversion into furfural by microwave-assisted pyrolysis. The isotopic content and location in furfural were determined from GC/MS and 13C NMR measurements and data analysis. Our results suggest that the carbon skeleton in furfural is mainly derived from the C-1 to C-5 of glucose. The C of the aldehyde group and the O of the furan ring in furfural are primarily originated from the C-1 and O-5 of glucose, respectively. For the first time, the source of the O of the furan ring in furfural was elucidated directly by experiments, which is consistent with predictions from recent quantum chemical calculations...
June 25, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28649330/dual-tracer-based-isotope-turnover-rates-in-a-highly-invasive-mysid-limnomysis-benedeni-from-lake-constance
#3
Elizabeth Yohannes, Karl-Otto Rothhaupt
Understanding the ecological patterns of invasive species and their habitats require an understanding of the species' foraging ecology. Stable carbon (δ(13)C) and nitrogen (δ(15)N) isotope values provide useful information into the study of animal ecology and evolution, since the isotope ratios of consumers reflect consumer's dietary patterns. Nevertheless, the lack of species- and element-specific laboratory-derived turnover rates could limit their application. Using a laboratory-based dual stable isotope tracer approach (Na(15) NO 3 and NaH(13) CO 3), we evaluated the δ(15)N and δ(13)C isotope turnover rates in full-grown adult invasive Limnomysis benedeni from Lake Constance...
June 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28625981/heterologous-expression-of-the-clostridium-carboxidivorans-co-dehydrogenase-alone-or-together-with-the-acetyl-coa-synthase-enables-clostridium-acetobutylicum-to-both-reduce-co2-and-oxidize-co
#4
Ellinor D Carlson, Eleftherios T Papoutsakis
With recent advances in synthetic biology, CO2 could be utilized as a carbon feedstock by native or engineered organisms, assuming the availability of electrons. Two key enzymes used in autotrophic CO2 fixation are the CO dehydrogenase (CODH) and acetyl-CoA synthase (ACS), which form a bifunctional heterotetrameric complex. CODH/ACS can reversibly catalyze CO2 to CO, effectively enabling a biological water-gas shift reaction at ambient temperatures and pressures. The CODH/ACS complex is part of the Wood-Ljungdahl pathway (WLP) used by acetogens to fix CO2 and has been well characterized in native hosts...
June 16, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28622800/analysis-of-stable-isotope-assisted-metabolomics-data-acquired-by-gc-ms
#5
Xiaoli Wei, Biyun Shi, Imhoi Koo, Xinmin Yin, Pawel Lorkiewicz, Hamid Suhail, Ramandeep Rattan, Shailendra Giri, Craig J McClain, Xiang Zhang
Stable isotope assisted metabolomics (SIAM) measures the abundance levels of metabolites in a particular pathway using stable isotope tracers (e.g., (13)C, (18)O and/or (15)N). We report a method termed signature ion approach for analysis of SIAM data acquired on a GC-MS system equipped with an electron ionization (EI) ion source. The signature ion is a fragment ion in EI mass spectrum of a derivatized metabolite that contains all atoms of the underivatized metabolite, except the hydrogen atoms lost during derivatization...
August 8, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28602094/stochastic-simulation-of-isotopic-exchange-mechanisms-for-fe-ii-catalyzed-recrystallization-of-goethite
#6
Piotr Zarzycki, Kevin M Rosso
Understanding Fe(II)-catalyzed transformations of Fe(III)-(oxyhydr)oxides is critical for correctly interpreting stable isotopic distributions and for predicting the fate of metal ions in the environment. Recent Fe isotopic tracer experiments have shown that goethite undergoes rapid recrystallization without phase change when exposed to aqueous Fe(II). The proposed explanation is oxidation of sorbed Fe(II) and reductive Fe(II) release coupled 1:1 by electron conduction through crystallites. Given the availability of two tracer exchange data sets that explore pH and particle size effects (e...
June 12, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28596540/preparation-and-in-vivo-characterization-of-51-mncl2-as-pet-tracer-of-ca-2-channel-mediated-transport
#7
Stephen A Graves, Reinier Hernandez, Hector F Valdovinos, Paul A Ellison, Jonathan W Engle, Todd E Barnhart, Weibo Cai, Robert J Nickles
Manganese has long been employed as a T1-shortening agent in magnetic resonance imaging (MRI) applications, but these techniques are limited by the biotoxicity of bulk-manganese. Positron emission tomography (PET) offers superior contrast sensitivity compared with MRI, and recent preclinical PET studies employing (52g)Mn (t1/2: 5.6 d, β(+): 29%) show promise for a variety of applications including cell tracking, neural tract tracing, immunoPET, and functional β-cell mass quantification. The half-life and confounding gamma emissions of (52g)Mn are prohibitive to clinical translation, but the short-lived (51)Mn (t1/2: 46 min, β(+): 97%) represents a viable alternative...
June 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28590131/iron-ii-catalyzed-iron-atom-exchange-and-mineralogical-changes-in-iron-rich-organic-freshwater-flocs-an-iron-isotope-tracer-study
#8
Laurel K ThomasArrigo, Christian Mikutta, James Byrne, Andreas Kappler, Ruben Kretzschmar
In freshwater wetlands, organic flocs are often found enriched in trace metal(loid)s associated with poorly crystalline Fe(III)-(oxyhydr)oxides. Under reducing conditions, flocs may become exposed to aqueous Fe(II), triggering Fe(II)-catalyzed mineral transformations and trace metal(loid) release. In this study, pure ferrihydrite, a synthetic ferrihydrite-polygalacturonic acid coprecipitate (16.7 wt % C), and As- (1280 and 1230 mg/kg) and organic matter (OM)-rich (18.1 and 21.8 wt % C) freshwater flocs dominated by ferrihydrite and nanocrystalline lepidocrocite were reacted with an isotopically enriched (57)Fe(II) solution (0...
June 7, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28589773/estimating-the-spatial-distribution-of-artificial-groundwater-recharge-using-multiple-tracers
#9
Christian Moeck, Dirk Radny, Adrian Auckenthaler, Michael Berg, Juliane Hollender, Mario Schirmer
Stable isotopes of water, organic micropollutants and hydrochemistry data are powerful tools for identifying different water types in areas where knowledge of the spatial distribution of different groundwater is critical for water resource management. An important question is how the assessments change if only one or a subset of these tracers is used. In this study, we estimate spatial artificial infiltration along an infiltration system with stage-discharge relationships and classify different water types based on the mentioned hydrochemistry data for a drinking water production area in Switzerland...
June 7, 2017: Isotopes in Environmental and Health Studies
https://www.readbyqxmd.com/read/28584941/-trophic-and-source-amino-acids-in-trophic-estimation-a-likely-metabolic-explanation
#10
REVIEW
T C O'Connell
Amino acid nitrogen isotopic analysis is a relatively new method for estimating trophic position. It uses the isotopic difference between an individual's 'trophic' and 'source' amino acids to determine its trophic position. So far, there is no accepted explanation for the mechanism by which the isotopic signals in 'trophic' and 'source' amino acids arise. Yet without a metabolic understanding, the utility of nitrogen isotopic analyses as a method for probing trophic relations, at either bulk tissue or amino acid level, is limited...
June 2017: Oecologia
https://www.readbyqxmd.com/read/28579536/effects-of-dietary-fructose-restriction-on-liver-fat-de-novo-lipogenesis-and-insulin-kinetics-in-children-with-obesity
#11
Jean-Marc Schwarz, Susan M Noworolski, Ayca Erkin-Cakmak, Natalie J Korn, Michael J Wen, Viva W Tai, Grace M Jones, Sergiu P Palii, Moises Velasco-Alin, Karen Pan, Bruce W Patterson, Alejandro Gugliucci, Robert H Lustig, Kathleen Mulligan
BACKGROUND & AIMS: Consumption of sugar is associated with obesity, type 2 diabetes mellitus, non-alcoholic fatty liver disease, and cardiovascular disease. The conversion of fructose to fat in liver (de novo lipogenesis, DNL) may be a modifiable pathogenetic pathway. We determined the effect of 9 days of isocaloric fructose restriction on DNL, liver fat, visceral fat (VAT), subcutaneous fat, and insulin kinetics in obese Latino and African American children with habitual high sugar consumption (fructose intake more than 50 g/day)...
June 1, 2017: Gastroenterology
https://www.readbyqxmd.com/read/28576319/chloroformate-derivatization-for-tracing-the-fate-of-amino-acids-in-cells-and-tissues-by-multiple-stable-isotope-resolved-metabolomics-msirm
#12
Ye Yang, Teresa W-M Fan, Andrew N Lane, Richard M Higashi
Amino acids have crucial roles in central metabolism, both anabolic and catabolic. To elucidate these roles, steady-state concentrations of amino acids alone are insufficient, as each amino acid participates in multiple pathways and functions in a complex network, which can also be compartmentalized. Stable Isotope-Resolved Metabolomics (SIRM) is an approach that uses atom-resolved tracking of metabolites through biochemical transformations in cells, tissues, or whole organisms. Using different elemental stable isotopes to label multiple metabolite precursors makes it possible to resolve simultaneously the utilization of these precursors in a single experiment...
July 11, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28569769/tracing-the-oxygen-isotope-composition-of-the-upper-earth-s-atmosphere-using-cosmic-spherules
#13
Andreas Pack, Andres Höweling, Dominik C Hezel, Maren T Stefanak, Anne-Katrin Beck, Stefan T M Peters, Sukanya Sengupta, Daniel Herwartz, Luigi Folco
Molten I-type cosmic spherules formed by heating, oxidation and melting of extraterrestrial Fe,Ni metal alloys. The entire oxygen in these spherules sources from the atmosphere. Therefore, I-type cosmic spherules are suitable tracers for the isotopic composition of the upper atmosphere at altitudes between 80 and 115 km. Here we present data on I-type cosmic spherules collected in Antarctica. Their composition is compared with the composition of tropospheric O2. Our data suggest that the Earth's atmospheric O2 is isotopically homogenous up to the thermosphere...
June 1, 2017: Nature Communications
https://www.readbyqxmd.com/read/28565921/interpretation-of-environmental-tracer-data-for-conceptual-understanding-of-groundwater-flow-an-application-for-fractured-aquifer-systems-in-the-k%C3%A5-odzko-basin-sudetes-poland
#14
Mariusz Mądrala, Mirosław Wąsik, Piotr Małoszewski
Environmental isotopes and hydrogeological data have been used for the construction of a conceptual model of fresh groundwater flow in the Kłodzko Basin, Sudetes, Poland. The model has allowed the verification of a groundwater circulation scheme resulting from the general morphological assumptions and the recharge role to the surrounding mountains. Combined interpretation of the tritium ages and the isotopic altitude effect allowed determining the volume of water-bearing rock Vr and hydrogeological parameters of systems drained by springs and wells...
May 31, 2017: Isotopes in Environmental and Health Studies
https://www.readbyqxmd.com/read/28562061/methane-and-benzene-in-drinking-water-wells-overlying-the-eagle-ford-fayetteville-and-haynesville-shale-hydrocarbon-production-areas
#15
Peter B McMahon, Jeannie R B Barlow, Mark A Engle, Kenneth Belitz, Patricia B Ging, Andrew G Hunt, Bryant C Jurgens, Yousif K Kharaka, Roland W Tollett, Timothy M Kresse
Water wells (n = 116) overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas were sampled for chemical, isotopic, and groundwater-age tracers to investigate the occurrence and sources of selected hydrocarbons in groundwater. Methane isotopes and hydrocarbon gas compositions indicate most of the methane in the wells was biogenic and produced by the CO2 reduction pathway, not from thermogenic shale gas. Two samples contained methane from the fermentation pathway that could be associated with hydrocarbon degradation based on their co-occurrence with hydrocarbons such as ethylbenzene and butane...
May 31, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28558433/testing-the-usefulness-of-222-rn-to-complement-conventional-hydrochemical-data-to-trace-groundwater-provenance-in-complex-multi-layered-aquifers-application-to-the-%C3%A3-beda-aquifer-system-ja%C3%A3-n-se-spain
#16
L Ortega, M Manzano, J Rodríguez-Arévalo
The Úbeda aquifer system is a multi-layered aquifer intensively exploited for irrigation. It covers 1100km(2) and consists of piled up sedimentary aquifer and aquitard layers from Triassic sandstones and clays at the bottom, to Jurassic carbonates (main exploited layer) in the middle, and Miocene sandstones and marls at the top. Flow network modification by intense exploitation and the existence of deep faults favour vertical mixing of waters from different layers and with distinct chemical composition. This induces quality loss and fosters risk of quantity restrictions...
December 1, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28544885/overcoming-interference-with-the-detection-of-a-stable-isotopically-labeled-microtracer-in-the-evaluation-of-beclabuvir-absolute-bioavailability-using-a-concomitant-microtracer-approach
#17
Hao Jiang, Craig Titsch, Jianing Zeng, Barry Jones, Philip Joyce, Yash Gandhi, Wesley Turley, Richard Burrell, Anne F Aubry, Mark E Arnold
The oral absolute bioavailability of beclabuvir in healthy subjects was determined using a microdose (100μg) of the stable isotopically labeled tracer via intravenous (IV) infusion started after oral dosing of beclabuvir (150mg). To simultaneously analyze the concentrations of the IV microtracer ([(13)C6]beclabuvir) and beclabuvir in plasma samples, a liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) method was initially developed. Surprisingly beclabuvir significantly interfered with the IV microtracer detection when using the selected reaction monitoring (SRM) in the assay...
May 17, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28527806/endogenous-synthesis-of-milk-oleic-acid-in-dairy-ewes-in-vivo-measurement-using-13-c-labeled-stearic-acid
#18
P G Toral, P Frutos, D Carreño, G Hervás
The use of stable isotopes is a reliable and risk-free alternative to radioactive tracers for directly examining in vivo fatty acid (FA) metabolism. However, very limited information is available in ruminants, and none is available in sheep. Therefore, we conducted an experiment in dairy ewes to determine, for the first time in this species, the uptake, Δ(9)-desaturation, and secretion of (13)C-labeled stearic acid (SA) into milk with the aim of measuring in vivo endogenous synthesis of milk oleic acid (OA) and stearoyl-CoA desaturase activity...
July 2017: Journal of Dairy Science
https://www.readbyqxmd.com/read/28527646/high-dose-amino-acid-administration-achieves-an-anabolic-response-in-type-2-diabetic-patients-that-is-independent-of-glycaemic-control-a-randomized-clinical-trial
#19
Chelsia Gillis, Patricia S Roque, Jürgen Bläss, Albert Urwyler, Harald Schepperle, Guido Kunz, Thomas Peters, Thomas Schricker, Linda Wykes, Andrea Kopp Lugli
BACKGROUND & AIMS: Surgical stress provokes protein catabolism and hyperglycaemia that is enhanced in patients with type 2 diabetes (T2DM), and increases perioperative morbidity. This study hypothesized that perioperative administration of high dose intravenous (IV) amino acids (AA) will augment protein balance in T2DM patients receiving tight plasma glucose control via continuous IV insulin compared to standard plasma glucose control via subcutaneous (SC) insulin sliding scale. METHODS: Eighteen patients with well-controlled T2DM (HbA1C% < 7...
May 3, 2017: Clinical Nutrition: Official Journal of the European Society of Parenteral and Enteral Nutrition
https://www.readbyqxmd.com/read/28522731/effect-of-metformin-on-bioactive-lipid-metabolism-in-insulin-resistant-muscle
#20
Piotr Zabielski, Marta Chacinska, Karol Charkiewicz, Marcin Baranowski, Jan Gorski, Agnieszka U Blachnio-Zabielska
Intramuscular accumulation of bioactive lipids leads to insulin resistance and type 2 diabetes (T2D). There is lack of consensus concerning which of the lipid mediators has the greatest impact on muscle insulin action in vivo Our aim was to elucidate the effects of high-fat diet (HFD) and metformin (Met) on skeletal muscle bioactive lipid accumulation and insulin resistance (IR) in rats. We employed a [U-(13)C]palmitate isotope tracer and mass spectrometry to measure the content and fractional synthesis rate (FSR) of intramuscular long-chain acyl-CoA (LCACoA), diacylglycerols (DAG) and ceramide (Cer)...
June 2017: Journal of Endocrinology
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