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isotopic tracer method

Mahalakshmi Shankaran, Gregg Czerwieniec, Chancy Fessler, Po-Yin Anne Wong, Salena Killion, Scott M Turner, Marc K Hellerstein, William J Evans
BACKGROUND: Muscle mass can be measured directly in vivo by isotope dilution, using Creatine-(methyl-d3 ) monohydrate (D3 -Cr) by mouth followed by measurement of the steady-state enrichment of D3 -creatinine (D3 -Crn) in urine. Isotope dilution methods require knowledge of the amount of tracer delivered to the pool of interest. In a subset of human subjects, a small amount of orally administered D3 -Cr 'spills' into urine after absorption and prior to transport into skeletal muscle cells...
April 16, 2018: Journal of Cachexia, Sarcopenia and Muscle
Ji-Hye Seo, Mukul Sharma, Erich Osterberg, Brian P Jackson
Here we use two chemical separation procedures to determine exceptionally low Os concentrations (~10-15 g g-1) and Os isotopic composition in polar snow/ice. Melt water weighing approximately 50 g is spiked with 190Os tracer solution and frozen at -20 °C in quartz-glass ampoules. A mixture of H2O2 and HNO3 is then added and the sample is heated to 300 °C at 100 bar using a High Pressure Asher. This allows tracer Os to be equilibrated with the sample as all Os species are oxidized to OsO4. The resulting OsO4 is extracted using either distillation (Method-I) or solvent-extraction (Method-II), purified, and measured using negative thermal ionization mass spectrometry (N-TIMS)...
April 8, 2018: Analytical Chemistry
Zhengjian Yang, Bao Cheng, Yaqian Xu, Defu Liu, Jun Ma, Daobin Ji
Eutrophication has become a severe environmental problem in some tributaries of the Three Gorges Reservoir (TGR) in China. A two-year field investigation of nutrients, oxygen stable isotopes (δ18 O), and hydrogen stable isotopes (δD) was performed from January 2010 to December 2011 to determine the sources of nutrients in Xiangxi Bay (XXB). The results showed that nitrogen, phosphorus and silicon varied seasonally depending on hydrodynamic changes. The bottom-layer intrusive density current decreased nitrogen and silicon concentrations and increase phosphorus concentrations in XXB, while the middle-layer intrusive density current increased nitrogen and silicon concentrations and decrease phosphorus concentrations...
April 5, 2018: Science of the Total Environment
Anastasia Loktev, Thomas Lindner, Walter Mier, Jürgen Debus, Annette Altmann, Dirk Jäger, Frederik Giesel, Clemens Kratochwil, Philippe Barthe, Christian Roumestand, Uwe Haberkorn
The tumor stroma, which accounts for a large part of the tumor mass, represents an attractive target for the delivery of diagnostic and therapeutic compounds. Here, the focus is notably on a subpopulation of stromal cells, known as cancer-associated fibroblasts (CAFs), which are present in more than 90% of epithelial carcinomas including pancreatic, colon and breast cancer. CAFs feature a high expression of fibroblast activation protein (FAP), which is not detectable in adult normal tissue but associated with a poor prognosis in cancer patients...
April 6, 2018: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Lara Stephens-Brown, Michael Davis
BACKGROUND: Exercise increases water requirements, but there is little information regarding water loss in dogs performing multi-day exercise OBJECTIVES: Quantify the daily water turnover of working dogs during multi-day exercise and establish the suitability of SC administration of tracer to determine water turnover. ANIMALS: Fifteen privately owned Labrador retrievers trained for explosive detection duties and 16 privately owned Alaskan Huskies conditioned for mid-distance racing...
March 23, 2018: Journal of Veterinary Internal Medicine
Sonja Cerar, Kim Mezga, Gorazd Žibret, Janko Urbanc, Marko Komac
Groundwater is the most important source of drinking water in the world. Therefore, information on the quality and quantity is important, as is new information related to the characteristics of the aquifer and the recharge area. In the present study we focused on the isotope composition of oxygen (δ18 O) in groundwater, which is a natural tracer and provides a better understanding of the water cycle, in terms of origin, dynamics and interaction. The groundwater δ18 O at 83 locations over the entire Slovenian territory was studied...
March 9, 2018: Science of the Total Environment
Helena Banning, Monika Stelling, Stephan König, Ronny Schoenberg, Thomas Neumann
Selenium (Se) is an important micronutrient but also a strong toxin with a narrow tolerance range for many organisms. As such, a globally heterogeneous Se distribution in soils is responsible for various disease patterns (i.e. Se excess and deficiency) and environmental problems, whereby plants play a key role for the Se entrance into the biosphere. Selenium isotope variations were proved to be a powerful tracer for redox processes and are therefore promising for the exploration of the species dependent Se metabolism in plants and the Se cycling within the Critical Zone...
2018: PloS One
Ying Chen, Olga Berejnaia, Jinqi Liu, Sheng-Ping Wang, Natalie A Daurio, Wu Yin, Rafael Mayoral, Aleksandr Petrov, Takhar Kasumov, Guo-Fang Zhang, Stephen F Previs, David E Kelley, David G McLaren
Numerous studies have implicated dyslipidemia as a key factor in mediating insulin resistance. Ceramides have received special attention since their levels are inversely associated with normal insulin signaling and positively associated with factors that are involved in cardiometabolic disease. Despite the growing literature surrounding ceramide biology, there are limited data regarding the activity of ceramide synthesis and turnover in vivo. Herein, we demonstrate the ability to measure ceramide kinetics by coupling the administration of [2 H]water with LC-MS/MS analyses...
March 6, 2018: American Journal of Physiology. Endocrinology and Metabolism
Thomas Brendan Smith, Kamlesh Patel, Haydn Munford, Andrew Peet, Daniel A Tennant, Mark Jeeves, Christian Ludwig
Tracing the fate of stable isotopically-enriched nutrients is a sophisticated method of describing and quantifying the activity of metabolic pathways. Nuclear Magnetic Resonance (NMR) offers high resolution data, yet is under-utilised due to length of time required to collect the data, quantification requiring multiple samples and complicated analysis. Here we present two techniques, quantitative spectral filters and enhancement of the splitting due to J-coupling in1 H,13 C-HSQC NMR spectra, which allow the rapid collection of NMR data in a quantitative manner on a single sample...
2018: Wellcome Open Research
Eszter Boros, Omar R Pinkhasov, Peter Caravan
Background: Current analytical methods for characterizing pharmacokinetic and metabolic properties of positron emission tomography (PET) and single photon emission computed tomography (SPECT) probes are limited. Alternative methods to study tracer metabolism are needed. The study objective was to assess the potential of high performance liquid chromatography - inductively coupled plasma - mass spectrometry (HPLC-ICP-MS) for quantification of molecular probe metabolism and pharmacokinetics using stable isotopes...
2018: EJNMMI Radiopharmacy and Chemistry
Laura Freije-Carrelo, Laura Alonso Sobrado, Mariella Moldovan, Jorge Ruiz Encinar, Jose Ignacio Garcia-Alonso
Dissolved inorganic carbon (DIC) is one of the most important parameters to be measured in seawaters for climate change studies. Its quantitative assessment requires analytical methodologies with overall uncertainties around 0.05% RSD for clear evaluation of temporal trends. Herein, two alternative Isotope Dilution Mass Spectrometry (IDMS) methodologies (on-line and species-specific) using an Isotope Ratio Mass Spectrometer (IRMS) and two calculation procedures for each methodology have been compared. As a result, a new method for the determination of DIC in seawaters, based on species-specific IDMS with Isotope Pattern Deconvolution calculation, was developed and validated...
March 2, 2018: Analytical Chemistry
Lishan Zheng, Xiaoyang Yang, Senchao Lai, Hong Ren, Siyao Yue, Yingyi Zhang, Xin Huang, Yuanguan Gao, Yele Sun, Zifa Wang, Pingqing Fu
Fine particles (PM2.5 ) samples, collected at Weizhou Island over the Gulf of Tonkin on a daytime and nighttime basis in the spring of 2015, were analyzed for primary and secondary organic tracers, together with organic carbon (OC), elemental carbon (EC), and stable carbon isotopic composition (δ13 C) of total carbon (TC). Five organic compound classes, including saccharides, lignin/resin products, fatty acids, biogenic SOA tracers and phthalic acids, were quantified by gas chromatography/mass spectrometry (GC/MS)...
February 26, 2018: Environmental Pollution
Cao Thi Thuy Hai, Nakamura Takashi, Saiki Makoto, Ta Thi Thao, Toyama Tadashi, Nishida Kei
RATIONALE: The isotopic tracer technique is widely used to identify the sources and fate of nitrogen (N) in order to understand the N cycle and contamination in water environments. The stable isotope ratio of ammonium is expected to greatly enhance the tracing analysis by combining it with the traditional nitrate isotope ratio. Diffusion followed by gas-phase trapping is the most commonly applied method for ammonium isotope ratio measurement. Although dissolved organic nitrogen (DON) is abundant in natural water and its breakdown in the diffusion procedure has been reported, the interference of DON with the measurement of ammonium isotope ratios has not been fully examined...
February 27, 2018: Rapid Communications in Mass Spectrometry: RCM
Peng Yi, Jing Yang, Yongdong Wang, Vincent de Paul Mugwanezal, Li Chen, Ala Aldahan
A good monitoring method is vital for understanding the sources of a water reservoir leakage and planning for effective restoring. Here we present a combination of several tracers (222Rn, oxygen and hydrogen isotopes, anions and temperature) for identification of water leakage sources in the Pushihe pumped storage power station which is in the Liaoning province, China. The results show an average 222Rn activity of 6843 Bq/m3 in the leakage water, 3034 Bq/m3 in the reservoir water, and 41,759 Bq/m3 in the groundwater...
February 5, 2018: Journal of Environmental Radioactivity
Ivonne Nijenhuis, Reiner Stollberg, Ute Lechner
The megasite Bitterfeld-Wolfen is highly contaminated as result of accidents and because of dumping of wastes from local chemical industries in the last century. A variety of contaminants including chlorinated ethenes and benzenes, hexachlorohexanes and chlorinated dioxins can still be found in the groundwater and (river) sediments. Investigations of the in situ microbial transformation of organohalides have been performed only over the last two decades at this megasite. In this review, we summarize the research on the activity of anaerobic dehalogenating bacteria at the field site in Bitterfeld-Wolfen, focusing on chlorinated ethenes, monochlorobenzene and chlorinated dioxins...
January 29, 2018: FEMS Microbiology Ecology
Lingling Yu, Chao Wen, Xing Li, Shiqi Fang, Lichuan Yang, Tony Wang, Kaifeng Hu
Quantification of endogenous and exogenous plasma glucose can help more comprehensively evaluate the glucose metabolic status. A ratio-based approach using isotope dilution liquid chromatography tandem mass spectrometry (ID LC-MS/MS) with indirect multiple reaction monitoring (MRM) of the derivative tag was developed to simultaneously quantify endo-/exogenous plasma glucose. Using diluted D-[13 C6 ] glucose as tracer of exogenous glucose, 12 C6 /13 C6 glucoses were first derivatized and then data were acquired in MRM mode...
March 2018: Analytical and Bioanalytical Chemistry
Vilém Zachleder, Milada Vítová, Monika Hlavová, Šárka Moudříková, Peter Mojzeš, Hermann Heumann, Johannes R Becher, Kateřina Bišová
Stable isotopes are used in wide fields of application from natural tracers in biology, geology and archeology through studies of metabolic fluxes to their application as tracers in quantitative proteomics and structural biology. We review the use of stable isotopes of biogenic elements (H, C, N, O, S, Mg, Se) with the emphasis on hydrogen and its heavy isotope deuterium. We will discuss the limitations of enriching various compounds in stable isotopes when produced in living organisms. Finally, we overview methods for measuring stable isotopes, focusing on methods for detection in single cells in situ and their exploitation in modern biotechnologies...
January 19, 2018: Biotechnology Advances
Christelle Guillermier, J Collin Poczatek, Walter R Taylor, Matthew L Steinhauser
In the field of secondary ion mass spectrometry at nanometer scale (NanoSIMS), configuration of parallel detectors to routinely measure isotope ratios in sub-100 nm domains brings classical stable isotope tracer studies from the whole tissue level down to the suborganelle level. Over the past decade, the marriage of stable isotope tracers with NanoSIMS has been applied to a range of fundamental biological questions that were largely inaccessible by other means. Although multiplexed measurement of different stable isotope tracers is feasible, in practice there remains a gap in the current analytical capacity to efficiently measure stable isotopes commonly utilized in tracer studies...
November 2017: International Journal of Mass Spectrometry
Maud Heuillet, Floriant Bellvert, Edern Cahoreau, Fabien Letisse, Pierre Millard, Jean-Charles Portais
Stable-isotope labeling experiments (ILEs) are widely used to investigate the topology and operation of metabolic networks. The quality of isotopic data collected in ILEs is of utmost importance to ensure reliable biological interpretations, but current evaluation approaches are limited due to a lack of suitable reference material and relevant evaluation criteria. In this work, we present a complete methodology to evaluate mass spectrometry (MS) methods used for quantitative isotopic studies of metabolic systems...
February 6, 2018: Analytical Chemistry
Ehsan F Aghdam, Anders M Fredenslund, Jeffrey Chanton, Peter Kjeldsen, Charlotte Scheutz
In this study, the total methane (CH4 ) generation rate and gas recovery efficiency at two Danish landfills were determined by field measurements. The landfills are located close to each other and are connected to the same gas collection system. The tracer gas dispersion method was used for quantification of CH4 emissions from the landfills, while the CH4 oxidation efficiency in the landfill cover layers was determined by stable carbon isotopic technique. The total CH4 generation rate was estimated by a first-order decay model (Afvalzorg) and was compared with the total CH4 generation rate determined by field measurements...
March 2018: Waste Management
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