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isotopic tracer method

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https://www.readbyqxmd.com/read/29027346/application-of-stable-isotope-labelling-techniques-for-the-detection-of-active-diazotrophs
#1
Roey Angel, Christopher Panhölzl, Raphael Gabriel, Craig Herbold, Wolfgang Wanek, Andreas Richter, Stephanie A Eichorst, Dagmar Woebken
Investigating active participants in the fixation of dinitrogen gas is vital as N is often a limiting factor for primary production. Biological nitrogen fixation (BNF) is performed by a diverse guild of bacteria and archaea (diazotrophs), which can be free-living or symbionts. Free-living diazotrophs are widely distributed in the environment, yet our knowledge about their identity and ecophysiology is still limited. A major challenge in investigating this guild is inferring activity from genetic data as this process is highly regulated...
October 13, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/28983702/measurement-of-the-15-n-14-n-ratio-of-phenylalanine-in-fermentation-matrix-by-isotope-ratio-mass-spectrometry
#2
Shiwei Zhang, Qiding Zhong, Daobing Wang, Zhanbin Huang, Guohui Li
OBJECTIVES: To determine the origin of (15)N-labeled phenylalanine in microbial metabolic flux analysis using (15)N as a tracer, a method for measuring phenylalanine δ(15)N using HPLC coupled with elemental analysis-isotope ratio mass spectrometry (EA-IRMS) was developed. RESULTS: The original source of the (15)N-labeled phenylalanine was determined using this new method that consists of three steps: optimization of the HPLC conditions, evaluation of the isotope fractionation effects, and evaluation of the effect of pre-processing on the phenylalanine nitrogen stable isotope...
October 5, 2017: Biotechnology Letters
https://www.readbyqxmd.com/read/28983132/modeling-the-isotopic-evolution-of-snowpack-and-snowmelt-testing-a-spatially-distributed-parsimonious-approach
#3
Pertti Ala-Aho, Doerthe Tetzlaff, James P McNamara, Hjalmar Laudon, Patrick Kormos, Chris Soulsby
Use of stable water isotopes has become increasingly popular in quantifying water flow paths and travel times in hydrological systems using tracer-aided modeling. In snow-influenced catchments, snowmelt produces a traceable isotopic signal, which differs from original snowfall isotopic composition because of isotopic fractionation in the snowpack. These fractionation processes in snow are relatively well understood, but representing their spatiotemporal variability in tracer-aided studies remains a challenge...
July 2017: Water Resources Research
https://www.readbyqxmd.com/read/28982052/radionuclides-as-natural-tracers-of-the-interaction-between-groundwater-and-surface-water-in-the-river-andarax-spain
#4
Francisco Navarro-Martinez, Alejandro Salas Garcia, Francisco Sánchez-Martos, Antonio Baeza Espasa, Luis Molina Sánchez, Antonio Rodríguez Perulero
The identification of specific aquifers that supply water to river systems is fundamental to understanding the dynamics of the rivers' hydrochemistry, particularly in arid and semiarid environments where river flow may be discontinuous. There are multiple methods to identify the source of river water. In this study of the River Andarax, in the Southeast of Spain, an analysis of natural tracers (physico-chemical parameters, uranium, radium and radon) in surface water and groundwater indicates that chemical parameters and uranium clearly identify the areas where there is groundwater-surface water interaction...
October 2, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/28972298/oxygen-isotope-analysis-of-levoglucosan-a-tracer-of-wood-burning-in-experimental-and-ambient-aerosol-samples
#5
J Blees, M Saurer, R T W Siegwolf, V Ulevicius, A S H Prevôt, J Dommen, M M Lehmann
RATIONALE: Levoglucosan is formed from cellulose during biomass burning. It is therefore often used as a specific tracer to quantify the contribution of wood burning to the aerosol loading. The stable oxygen isotope composition (δ(18) O value) of biomass is determined by the water cycle and varies regionally, and hence the δ(18) O value of levoglucosan could help to identify source regions of organic aerosols. METHODS: After solvent extraction of the organic fraction and concentration steps, a recently developed methylation derivatisation technique was applied on experimental (i...
October 3, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28960906/hplc-ms-ms-a-potential-method-to-track-the-in-vivo-degradation-of-zein-based-biomaterial
#6
Hua-Jie Wang, Shunji Kato, Yue Zhang, Kiyotaka Nakagawa, Teruo Miyazawa, Jin-Ye Wang
Given the inadequacies of existing clinic tracking strategies, such as isotopic tracer techniques, one of the major thrusts in protein-based tissue engineering substitutes prior to use in clinic is to develop a safe technique that can effectively track their degradation in vivo. Keeping in view the possible application of a natural polymer, zein as a novel bone substitute, with the advantages of good bio-compatibility, bio-degradability and outstanding mechanical properties, we attempted here to construct a HPLC-MS/MS method to track the in vivo degradation of zein porous scaffold...
September 29, 2017: Journal of Biomedical Materials Research. Part A
https://www.readbyqxmd.com/read/28938478/roux-en-y-gastric-bypass-surgery-has-unique-effects-on-postprandial-fgf21-but-not-fgf19-secretion
#7
Lydia-Ann L S Harris, Gordon I Smith, Bettina Mittendorfer, J Christopher Eagon, Adewole L Okunade, Bruce W Patterson, Samuel Klein
Context: Fibroblast growth factors (FGF) 19 and FGF21 are secreted by the intestine and liver in response to macronutrient intake. Intestinal resection and reconstruction via bariatric surgery may alter their regulation. Objective: We tested the hypothesis that weight loss induced by Roux-en-Y gastric bypass (RYGB) surgery, but not matched weight loss induced by laparoscopic adjustable gastric banding (LAGB), increases postprandial plasma FGF19 and FGF21 concentrations...
August 17, 2017: Journal of Clinical Endocrinology and Metabolism
https://www.readbyqxmd.com/read/28931590/leucine-transamination-is-lower-in-middle-aged-compared-with-younger-adults
#8
Paolo Tessari
Background: Insulin and age affect leucine (and protein) kinetics in vivo. However, to our knowledge, leucine transamination and the effects of insulin have not been studied in participants of different ages.Objective: The aims of the study were to measure whole-body leucine deamination to α-ketoisocaproate (KIC) and KIC reamination to leucine in middle-aged and younger healthy adults, both in the postabsorptive state and after hyperinsulinemia.Methods: Younger (mean ± SE age: 26 ± 2 y) and middle-aged (54 ± 3 y) healthy men and women were enrolled...
September 20, 2017: Journal of Nutrition
https://www.readbyqxmd.com/read/28921623/one-step-synthesis-of-18-f-cabozantinib-for-use-in-positron-emission-tomography-imaging-of-c-met
#9
Vegard Torp Lien, Jo Klaveness, Dag Erlend Olberg
Cabozantinib is an FDA approved kinase inhibitor for the treatment of medullary thyroid cancer and advanced renal cell carcinoma, which exerts its therapeutic effect by inhibiting, among others, the tyrosine kinase c-Met. Non-invasive imaging techniques are becoming increasingly important clinically to ensure drug efficacy, staging, monitoring and patient stratification. PET isotope labelled tyrosine kinase inhibitors have, for the same reason, potential as PET tracers for imaging of various cancers. Based on cabozantinib, we synthesized the novel boronic acid pinacol ester 4 as a labelling precursor, where the boronic ester moiety replaces the fluorine native to this kinase inhibitor...
September 18, 2017: Journal of Labelled Compounds & Radiopharmaceuticals
https://www.readbyqxmd.com/read/28916097/determination-of-99-tc-in-fresh-water-using-tru-resin-by-icp-ms
#10
Nicolas Guérin, Remi Riopel, Sheila Kramer-Tremblay, Nimal de Silva, Jack Cornett, Xiongxin Dai
Technetium-99 ((99)Tc) determination at trace level by inductively coupled plasma mass spectrometry (ICP-MS) is challenging because there is no readily available appropriate Tc isotopic tracer. A new method using Re as a recovery tracer to determine (99)Tc in fresh water samples, which does not require any evaporation step, was developed. Tc(VII) and Re(VII) were pre-concentrated on a small anion exchange resin (AER) cartridge from one litre of water sample. They were then efficiently eluted from the AER using a potassium permanganate (KMnO4) solution...
October 2, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28858432/imaging-lymphatics-in-human-normal-and-lymphedema-limbs-usefulness-of-various-modalities-for-evaluation-of-lymph-and-edema-fluid-flow-pathways-and-dynamics
#11
Marzanna T Zaleska, Waldemar L Olszewski
The human lymphatic system morphology and function still remain largely unknown to clinicians and biologists. How does the lymphatic vascular system look like in comparison to the blood transport system, how does lymph flow, where does capillary filtrate accumulate in cases with lymphatic obstruction caused by inflammation, trauma and cancer therapy, remain as basic questions. Visualization of the lymphatic pathways and dynamics of lymph flow, and in cases of obstruction, the localization of the capillary filtrate/edema fluid accumulation becomes indispensable...
August 31, 2017: Journal of Biophotonics
https://www.readbyqxmd.com/read/28826376/nutrition-from-the-inside-out
#12
Dennis M Bier
Nearly 50 years ago, I set out to investigate the clinical problem of hypoglycemia in children with illnesses that limited their food intake. My goal was to gather accurate and precise measurable data. At the time, I wasn't interested in nutrition as a discipline defined in its more general or popular sense. To address the specific problem that interested me required development of entirely new methods based on stable, nonradioactive tracers that satisfied the conditions of accuracy and precision. At the time, I had no inclination of the various theoretical and practical problems that would have to be solved to achieve this goal...
August 21, 2017: Annual Review of Nutrition
https://www.readbyqxmd.com/read/28811296/a-novel-d2o-tracer-method-to-quantify-rna-turnover-as-a-biomarker-of-de-novo-ribosomal-biogenesis-in-vitro-in-animal-models-and-in-human-skeletal-muscle
#13
Matthew S Brook, Daniel J Wilkinson, W Kyle Mitchell, Jonathan L Lund, Bethan E Phillips, Nathaniel J Sweczyk, Heikki Kainulainen, Sanna Lensu, Lauren G Koch, Steve L Britton, Paul L Greenhaff, Kenneth Smith, Philip J Atherton
Current methods to quantify RNA dynamics are beset with limitations. Here, we developed a novel stable isotope (D2O)-methodology to quantify RNA synthesis (i.e. ribosomal biogenesis) in cells, animal models, and humans. Firstly, proliferating C2C12 cells were incubated in D2O-enriched media and myotubes (±) 50ng.ml(-1) IGF-1. Secondly, rat quadriceps [untrained n=9; 7-wks interval-"like" training n=13] were collected after ~3-wks D2O (70-Atom%) administration, with body-water enrichment (BWE) monitored via blood sampling...
August 15, 2017: American Journal of Physiology. Endocrinology and Metabolism
https://www.readbyqxmd.com/read/28776982/flux-analysis-of-free-amino-sugars-and-amino-acids-in-soils-by-isotope-tracing-with-a-novel-liquid-chromatography-high-resolution-mass-spectrometry-platform
#14
Yuntao Hu, Qing Zheng, Wolfgang Wanek
Soil fluxomics analysis can provide pivotal information for understanding soil biochemical pathways and their regulation, but direct measurement methods are rare. Here, we describe an approach to measure soil extracellular metabolite (amino sugar and amino acid) concentrations and fluxes based on a (15)N isotope pool dilution technique via liquid chromatography and high-resolution mass spectrometry. We produced commercially unavailable (15)N and (13)C labeled amino sugars and amino acids by hydrolyzing peptidoglycan isolated from isotopically labeled bacterial biomass and used them as tracers ((15)N) and internal standards ((13)C)...
September 5, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28747484/a-simple-plasma-retinol-isotope-ratio-method-for-estimating-%C3%AE-carotene-relative-bioefficacy-in-humans-validation-with-the-use-of-model-based-compartmental-analysis
#15
Jennifer Lynn Ford, Joanne Balmer Green, Georg Lietz, Anthony Oxley, Michael H Green
Background: Provitamin A carotenoids are an important source of dietary vitamin A for many populations. Thus, accurate and simple methods for estimating carotenoid bioefficacy are needed to evaluate the vitamin A value of test solutions and plant sources. β-Carotene bioefficacy is often estimated from the ratio of the areas under plasma isotope response curves after subjects ingest labeled β-carotene and a labeled retinyl acetate reference dose [isotope reference method (IRM)], but to our knowledge, the method has not yet been evaluated for accuracy...
September 2017: Journal of Nutrition
https://www.readbyqxmd.com/read/28742073/biological-nitrogen-fixation-in-the-oxygen-minimum-region-of-the-eastern-tropical-north-pacific-ocean
#16
Amal Jayakumar, Bonnie X Chang, Brittany Widner, Peter Bernhardt, Margaret R Mulholland, Bess B Ward
Biological nitrogen fixation (BNF) was investigated above and within the oxygen-depleted waters of the oxygen-minimum zone of the Eastern Tropical North Pacific Ocean. BNF rates were estimated using an isotope tracer method that overcame the uncertainty of the conventional bubble method by directly measuring the tracer enrichment during the incubations. Highest rates of BNF (~4 nM day(-1)) occurred in coastal surface waters and lowest detectable rates (~0.2 nM day(-1)) were found in the anoxic region of offshore stations...
October 2017: ISME Journal
https://www.readbyqxmd.com/read/28737889/application-of-resonance-ionization-mass-spectrometry-for-ultratrace-analysis-of-technetium
#17
Pascal Schönberg, Christoph Mokry, Jörg Runke, Daniela Schönenbach, Nils Stöbener, Petra Thörle-Pospiech, Norbert Trautmann, Tobias Reich
This work shows the ability of resonance ionization mass spectrometry (RIMS) to determine (99g)Tc at the ultratrace level. The characterization of the prepared samples by X-ray photoelectron spectroscopy (XPS) and optimization of the RIMS setup for this purpose, as well as the application of the RIMS method to a soil sample, are presented in this article. (97)Tc was used as a tracer isotope to determine the amount of (99g)Tc in a soil sample with RIMS. With 8.8 × 10(10) atoms of (97)Tc as the tracer, the concentration of (99g)Tc was found to be 1...
September 5, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28734989/hydroxyvitamin-d-assays-an-historical-perspective-from-deqas
#18
G D Carter, J Berry, R Durazo-Arvizu, E Gunter, G Jones, J Jones, H L J Makin, P Pattni, C T Sempos, P Twomey, E L Williams, S A Wise
Recent years have seen a substantial increase in demand for 25-hydroxyvitamin D (25-OHD) assays. DEQAS (the Vitamin D External Quality Assessment Scheme) has been monitoring the performance of these assays since 1989. The first DEQAS distribution was in June 1989 and results were submitted by 13 laboratories in the UK, two of which used HPLC/UV; the rest used ligand binding assays with a tritium tracer. Inter-laboratory CVs (ALTM) ranged from 29.3% (42.7 nmol/L) to 53.7% (20.0 nmol/L). Currently the scheme has participants in 56 countries using 30 methods or variants of methods...
July 19, 2017: Journal of Steroid Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28727110/calibration-and-validation-of-a-carbon-oxidation-system-and-determination-of-the-bicarbonate-retention-factor-and-the-dietary-phenylalanine-requirement-in-the-presence-of-excess-tyrosine-of-adult-female-mixed-breed-dogs
#19
A K Shoveller, J J Danelon, J L Atkinson, G M Davenport, R O Ball, P B Pencharz
Carbon oxidation methods have been used as rapid and sensitive methods to determine whole-body AA requirements in multiple species. The objectives of the current studies were to validate complete CO recovery, determine the bicarbonate retention factor, and estimate the Phe requirement, in the presence of excess Tyr, in adult dogs using the direct oxidation technique. In this series of studies, 2 oxidation chambers were constructed and calibrated to ensure accurate collection of breath CO. First, 104.6 ± 7...
July 2017: Journal of Animal Science
https://www.readbyqxmd.com/read/28724692/enhancing-studies-of-pharmacodynamic-mechanisms-via-measurements-of-metabolic-flux-fundamental-concepts-and-guiding-principles-for-using-stable-isotope-tracers
#20
REVIEW
Natalie A Daurio, Sheng-Ping Wang, Ying Chen, Haihong Zhou, David G McLaren, Thomas P Roddy, Douglas G Johns, Denise Milot, Takhar Kasumov, Mark D Erion, David E Kelley, Stephen F Previs
Drug discovery and development efforts are largely based around a common expectation, namely, that direct or indirect action on a cellular process (e.g., statin-mediated enzyme inhibition or insulin-stimulated receptor activation) will have a beneficial impact on physiologic homeostasis. To expand on this, one could argue that virtually all pharmacologic interventions attempt to influence the flow of "traffic" in a biochemical network, irrespective of disease or modality. Since stable isotope tracer kinetic methods provide a measure of traffic flow (i...
October 2017: Journal of Pharmacology and Experimental Therapeutics
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