keyword
MENU ▼
Read by QxMD icon Read
search

Isotope tracer

keyword
https://www.readbyqxmd.com/read/27906461/measurement-of-intestinal-and-peripheral-cholesterol-fluxes-by-a-dual-tracer-balance-method
#1
Onne A H O Ronda, Theo H van Dijk, H J Verkade, Albert K Groen
Long-term elevated plasma cholesterol levels put individuals at risk for developing atherosclerosis. Plasma cholesterol levels are determined by the balance between cholesterol input and output fluxes. Here we describe in detail the methodology to determine the different cholesterol fluxes in mice. The percentage of absorbed cholesterol is calculated from a stable isotope-based double-label method. Cholesterol synthesis is calculated from MIDA after (13) C-acetate enrichment. Cholesterol is removed from the body via the feces...
December 1, 2016: Current Protocols in Mouse Biology
https://www.readbyqxmd.com/read/27903832/predictors-of-the-size-of-the-exchangeable-zinc-pool-differ-between-children-and-adults
#2
Leland V Miller, K Michael Hambidge, Janet C King, Jamie E Westcott, Nancy F Krebs
BACKGROUND: The size of the rapidly exchanging pool of body zinc has been suggested as having potential utility as a biomarker of zinc status. Knowledge of the relations of exchangeable zinc pool (EZP) size to relevant variables is necessary to adequately evaluate its use as a biomarker. OBJECTIVE: We used regression analysis to investigate associations of EZP with age, sex, body size, and zinc nutrition variables. METHODS: Data were compiled from 18 isotope tracer studies of zinc absorption in 247 children and adults (248 observations) in which EZP and relevant variables (e...
November 30, 2016: Journal of Nutrition
https://www.readbyqxmd.com/read/27896775/uplc-ms-ms-determination-of-deuterated-25-hydroxyvitamin-d-d3-25ohd3-and-other-vitamin-d-metabolites-for-the-measurement-of-25ohd-half-life
#3
Shima Assar, Inez Schoenmakers, Albert Koulman, Ann Prentice, Kerry S Jones
Plasma 25-hydroxyvitamin D (25OHD) half-life (25OHDt 1/2) is a dynamic marker of vitamin D metabolism that can be used to assess vitamin D expenditure and help inform vitamin D requirements. Our group recently established an approach to determine the 25OHDt 1/2 as an alternative biomarker of 25OHD expenditure in humans. The approach uses a small oral dose of stable isotope labeled 25OHD3 [3-(2)H-25OHD(3) (6,19,19-d3)] (d3-25OHD3) (tracer), which is distinguishable from endogenous 25OHD by liquid chromatography tandem-mass spectrometry (LC-MS/MS)...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/27889577/brain-uptake-and-metabolism-of-the-endocannabinoid-anandamide-labeled-in-either-the-arachidonoyl-or-ethanolamine-moiety
#4
Kun Hu, Shilpa Sonti, Sherrye T Glaser, Richard I Duclos, Samuel J Gatley
INTRODUCTION: Anandamide (N-arachidonoylethanolamine) is a retrograde neuromodulator that activates cannabinoid receptors. The concentration of anandamide in the brain is controlled by fatty acid amide hydrolase (FAAH), which has been the focus of recent drug discovery efforts. Previous studies in C57BL/6 mice using [(3)H-arachidonoyl]anandamide demonstrated deposition of tritium in thalamus and cortical areas that was blocked by treatment with an FAAH inhibitor and that was not seen in FAAH-knockout mice...
November 9, 2016: Nuclear Medicine and Biology
https://www.readbyqxmd.com/read/27887574/fluxfix-automatic-isotopologue-normalization-for-metabolic-tracer-analysis
#5
Sophie Trefely, Peter Ashwell, Nathaniel W Snyder
BACKGROUND: Isotopic tracer analysis by mass spectrometry is a core technique for the study of metabolism. Isotopically labeled atoms from substrates, such as [(13)C]-labeled glucose, can be traced by their incorporation over time into specific metabolic products. Mass spectrometry is often used for the detection and differentiation of the isotopologues of each metabolite of interest. For meaningful interpretation, mass spectrometry data from metabolic tracer experiments must be corrected to account for the naturally occurring isotopologue distribution...
November 25, 2016: BMC Bioinformatics
https://www.readbyqxmd.com/read/27884075/srm-based-measurements-of-proprotein-convertase-subtilisin-kexin-type-9-and-lipoprotein-a-kinetics-in-nonhuman-primate-serum
#6
Fang Xie, Maurice G Emery, John P Gibbs, Dan A Rock, Brooke M Rock
AIM: PCSK9 and Lp(a) have been identified as potential biomarkers for cardiovascular disease. The ability to measure protein turnover rates will provide insights into the dynamic properties of these proteins and lead to better understanding of their biological roles. We aimed to implement the stable isotope-labeled tracers ([(2)H3]-leucine) and develop a novel LC-selected reaction monitoring (SRM) mass spectrometry (MS) method to study the kinetics of PCSK9 and Lp(a). RESULTS: A sensitive method using immunoaffinity enrichment coupled with LC-SRM MS was developed to measure the production and degradation rates of PCSK9 and Lp(a) in naive nonhuman primate serum...
December 2016: Bioanalysis
https://www.readbyqxmd.com/read/27878973/metabolite-labelling-reveals-hierarchies-in-clostridium-acetobutylicum-that-selectively-channel-carbons-from-sugar-mixtures-towards-biofuel-precursors
#7
Ludmilla Aristilde
Clostridial fermentation of cellulose and hemicellulose relies on the cellular physiology controlling the metabolism of the cellulosic hexose sugar (glucose) with respect to the hemicellulosic pentose sugars (xylose and arabinose) and the hemicellulosic hexose sugars (galactose and mannose). Here, liquid chromatography-mass spectrometry and stable isotope tracers in Clostridium acetobutylicum were applied to investigate the metabolic hierarchy of glucose relative to the different hemicellulosic sugars towards two important biofuel precursors, acetyl-coenzyme A and butyryl-coenzyme A...
November 22, 2016: Microbial Biotechnology
https://www.readbyqxmd.com/read/27870030/fish-introductions-and-light-modulate-food-web-fluxes-in-tropical-streams-a-whole-ecosystem-experimental-approach
#8
Sarah M Collins, Steven A Thomas, Thomas Heatherly, Keeley L MacNeill, Antoine O H C Leduc, Andrés López-Sepulcre, Bradley A Lamphere, Rana W El-Sabaawi, David N Reznick, Catherine M Pringle, Alexander S Flecker
Decades of ecological study have demonstrated the importance of top-down and bottom-up controls on food webs, yet few studies within this context have quantified the magnitude of energy and material fluxes at the whole-ecosystem scale. We examined top-down and bottom-up effects on food web fluxes using a field experiment that manipulated the presence of a consumer, the Trinidadian guppy Poecilia reticulata, and the production of basal resources by thinning the riparian forest canopy to increase incident light...
November 2016: Ecology
https://www.readbyqxmd.com/read/27866737/enhanced-nitrogen-loss-from-rivers-through-coupled-nitrification-denitrification-caused-by-suspended-sediment
#9
Xinghui Xia, Ting Liu, Zhifeng Yang, Greg Michalski, Shaoda Liu, Zhimei Jia, Sibo Zhang
Present-day estimations of global nitrogen loss (N-loss) are underestimated. Commonly, N-loss from rivers is thought to be caused by denitrification only in bed-sediments. However, coupled nitrification-denitrification occurring in overlying water with suspended sediments (SPS) where oxic and anoxic/low oxygen zones may coexist is ignored for N-loss in rivers. Here the Yellow and Yangtze Rivers were taken as examples to investigate the effect of SPS, which exists in many rivers of the world, on N loss through coupled nitrification-denitrification with nitrogen stable ((15)N) isotopic tracer simulation experiments and in-situ investigation...
November 17, 2016: Science of the Total Environment
https://www.readbyqxmd.com/read/27843065/measuring-radon-222-in-soil-gas-with-high-spatial-and-temporal-resolution
#10
Darren Huxtable, David Read, George Shaw
In order to exploit (222)Rn as a naturally-occurring tracer in soils we need to sample and measure radon isotopes in soil gas with high spatial and temporal resolution, without disturbing in situ activity concentrations and fluxes. Minimisation of sample volume is key to improving the resolution with which soil gas can be sampled; an analytical method is then needed which can measure radon with appropriate detection limits and precision for soil gas tracer studies. We have designed a soil gas probe with minimal internal dead volume to allow us to sample soil gas volumes of 45 cm(3)...
November 11, 2016: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/27832302/rapid-ion-exchange-matrix-removal-for-a-decrease-of-detection-limits-in-the-analysis-of-salt-rich-reservoir-waters-for-fluorobenzoic-acids-by-liquid-chromatography-coupled-with-tandem-mass-spectrometry
#11
Paweł Kubica, Véronique Vacchina, Tomasz Wasilewski, Stéphanie Reynaud, Joanna Szpunar, Ryszard Lobinski
A matrix removal procedure with ion-exchange resin prior to analysis for 18 fluorinated benzoic acids (FBAs) tracers in saline (>25% salt) reservoir water was optimized. The elimination of >98% of salt and the simultaneous matrix sample cleanup allowed the direct analysis using the supernatant by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). This resulted in a gain in detection limits for most of the tracers in comparison with the reference method (direct analysis after minimum required dilution)...
November 10, 2016: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/27823829/trace-metal-pollution-and-carbon-and-nitrogen-isotope-tracing-through-the-yongdingxin-river-estuary-in-bohai-bay-northern-china
#12
Conghui Sun, Qi Wei, Lixia Ma, Li Li, Guanghong Wu, Ling Pan
A tide gate was built in 2010 to prevent seawater from moving upstream into the Yongdingxin River estuary in Bohai Bay, Northern China. We analysed the concentrations of Hg, Cd, Pb, TOC, TN, δ(13)C and δ(15)N and studied their variations in the surface layer and vertical profiles of sediment cores collected from the Yongdingxin River estuary. Contamination factors and geo-accumulation indices were calculated for each metal, which revealed high levels of contamination for Hg and Cd in the sediments, likely from anthropogenic sources...
November 4, 2016: Marine Pollution Bulletin
https://www.readbyqxmd.com/read/27804265/hepatic-steatosis-is-common-in-adolescents-with-obesity-and-pcos-and-relates-to-de-novo-lipogenesis-but-not-insulin-resistance
#13
Melanie Cree-Green, Bryan C Bergman, Gregory V Coe, Lindsey Newnes, Amy D Baumgartner, Samantha Bacon, Ann Sherzinger, Laura Pyle, Kristen J Nadeau
OBJECTIVE: Increased liver fat and type 2 diabetes are prevalent in women with polycystic ovarian syndrome (PCOS) and cause excess mortality, yet little is known about their development during adolescence. The objective of this study was to measure hepatic steatosis and related metabolic contributors in girls with obesity, with and without PCOS. METHODS: Nondiabetic adolescents with obesity, 41 with PCOS (PCOS; age 15.0 [13.0-16.0] years, BMI 35.2 ± 0.61 kg/m(2) ) and 30 without PCOS (OB; age 14...
November 2016: Obesity
https://www.readbyqxmd.com/read/27801618/a-multi-analyte-immunoassay-for-thyroid-related-analytes
#14
Bharti Jain, J Kumarasamy, C Gholve, Savita Kulkarni, M G R Rajan
We describe the development and validation of multianalyte immunoassays (MAIA) for three analytes, viz., thyroxine (T4), thyroid stimulating hormone (TSH) and thyroglobulin (Tg) essential for assessment of thyroid function but having widely varying molecular weights. Using polycarbonate (PC) track-etched membranes (TEM) as an immobilization support and (125)I as the tracer, both competitive assay for T4 and non-competitive assay for TSH and Tg were performed on the same TEM. MAIA was found to be highly sensitive and precise with clinically useful working range and correlated very well with individual analyte immunoassays...
November 1, 2016: Journal of Immunoassay & Immunochemistry
https://www.readbyqxmd.com/read/27798119/carrot-solution-culture-bioproduction-of-uniformly-labeled-13c-lutein-and-in%C3%A2-vivo-dosing-in-non-human-primates
#15
Joshua W Smith, Randy B Rogers, Sookyoung Jeon, Stanislav S Rubakhin, Lin Wang, Jonathan V Sweedler, Martha Neuringer, Matthew J Kuchan, John W Erdman
Lutein is a xanthophyll abundant in nature and most commonly present in the human diet through consumption of leafy green vegetables. With zeaxanthin and meso-zeaxanthin, lutein is a component of the macular pigment of the retina, where it protects against photooxidation and age-related macular degeneration. Recent studies have suggested that lutein may positively impact cognition throughout the lifespan, but outside of the retina, the deposition, metabolism, and function(s) of lutein are poorly understood...
October 20, 2016: Experimental Biology and Medicine
https://www.readbyqxmd.com/read/27797199/uranium-isotope-fractionation-during-adsorption-co-precipitation-and-biotic-reduction
#16
Duc Huy Dang, Breda Novotnik, Wei Wang, R Bastian Georg, Robert Douglas Evans
Uranium contamination of surface environments is a problem associated with both U-ore extraction/processing and situations in which groundwater comes into contact with geological formations high in uranium. Apart from the environmental concerns about U contamination, its accumulation and isotope composition have been used in marine sediments as a paleo-proxy of the Earth' oxygenation history. Understanding U isotope geochemistry is then essential either to develop sustainable remediation procedures as well as for use in paleo-tracer applications...
October 31, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/27792952/hydrochemical-and-isotopes-studies-in-a-hypersaline-wetland-to-define-the-hydrogeological-conceptual-model-fuente-de-piedra-lake-malaga-spain
#17
F J Montalván, J Heredia, J M Ruiz, E Pardo-Igúzquiza, A García de Domingo, F J Elorza
The Fuente de Piedra lake is a hypersaline wetland of great extension (13.5km(2)) and rich in aquatic birds and other species. It became therefore the third Spanish wetland to be included in the Ramsar convention and has been a "nature reserve" since 1984. The lake has an endorheic basin (150km(2)) with variable-density flows dominated by complex hydrogeological conditions. The traditional conceptualization of endorheic basins in semiarid climates considered that the brine in this hydric system was exclusively of evaporative origin and was placed only in the lake and its surrounding discharge area in the basin...
October 25, 2016: Science of the Total Environment
https://www.readbyqxmd.com/read/27780112/tracing-metabolism-from-lignocellulosic-biomass-and-gaseous-substrates-to-products-with-stable-isotopes
#18
REVIEW
Jacqueline E Gonzalez, Maciek R Antoniewicz
Engineered microbes offer a practical and sustainable alternative to traditional industrial approaches. To increase the economic feasibility of biological processes, microbial isolates are engineered to take up inexpensive feedstocks (including lignocellulosic biomass, syngas, methane, and carbon dioxide), and convert them into substrates of central metabolism and further into value-added products. To trace the metabolism of these feedstocks into products, isotopic tracers are applied together with isotopomer analysis techniques such as (13)C-metabolic flux analysis to provide a detailed picture of pathway utilization...
October 22, 2016: Current Opinion in Biotechnology
https://www.readbyqxmd.com/read/27780103/cliff-nesting-seabirds-influence-production-and-sediment-chemistry-of-lakes-situated-above-their-colony
#19
K E Hargan, N Michelutti, K Coleman, C Grooms, J M Blais, L E Kimpe, G Gilchrist, M Mallory, J P Smol
Seabirds that congregate in large numbers during the breeding season concentrate marine-derived nutrients to their terrestrial nesting sites, and these nutrients disperse and enhance production in nearby terrestrial, freshwater and marine ecosystems. In the Canadian Arctic, large seabird colonies (>100,000 breeding pairs) nest on cliff faces that drain directly in the ocean, ultimately returning the nutrients back to the marine environment from which they were derived. However, strong winds blowing up cliff faces could transport nutrients up in elevation and onto surrounding terrestrial and aquatic environments...
October 22, 2016: Science of the Total Environment
https://www.readbyqxmd.com/read/27766703/a-simple-and-reliable-anion-exchange-resin-method-for-sulfate-extraction-and-purification-suitable-for-multiple-o-and-s-isotope-measurements
#20
Erwann Le Gendre, Erwan Martin, Benoit Villemant, Pierre Cartigny, Nelly Assayag
RATIONALE: The O- and S- isotope compositions of sulfates can be used as key tracers of the fate and sink of sulfate in both terrestrial and extra-terrestrial environments. However, their application remains limited in those geological systems where sulfate occurs in low concentrations. Here we present a simple and reliable method to extract, purify and concentrate sulfate from natural samples. The method allows us to take into account the separation of nitrate, which is known to be an issue in O-isotope analysis...
October 21, 2016: Rapid Communications in Mass Spectrometry: RCM
keyword
keyword
41874
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"