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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
#1
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
#2
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, 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 physiological homeostasis. To expand on this, one could argue that virtually all pharmacological 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...
July 19, 2017: Journal of Pharmacology and Experimental Therapeutics
https://www.readbyqxmd.com/read/28714921/accumulation-of-microcystin-lr-rr-and-yr-in-three-freshwater-bivalves-in-microcystis-aeruginosa-bloom-using-dual-isotope-tracer
#3
Min-Seob Kim, Yeon-Jung Lee, Sun-Yong Ha, Baik-Ho Kim, Soon-Jin Hwang, Jung-Taek Kwon, Jong-Woo Choi, Kyung-Hoon Shin
Abstract: Stable isotope tracers were first applied to evaluate the Microcystis cell assimilation efficiency of Sinanodonta bivalves, since the past identification method has been limited to tracking the changes of each chl-a, clearity, and nutrient. The toxicity profile and accumulation of MC-LR, -RR and -YR in different organs (foot and digestive organs) from the three filter-feeders (Sinanodonta woodina, Sinanodonta arcaeformis, and Unio douglasiae) were assessed under the condition of toxigenic cyanobacteria (Microcystis aeruginosa) blooms through an in situ pond experiment using (13)C and (15)N dual isotope tracers...
July 17, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28713554/growth-hormone-receptor-antagonism-with-pegvisomant-in-insulin-resistant-non-diabetic-men-a-phase-ii-pilot-study
#4
Ada P Lee, Kathleen Mulligan, Morris Schambelan, Elizabeth J Murphy, Ethan J Weiss
Background: Growth hormone (GH) is known to affect insulin and glucose metabolism.  Blocking its effects in acromegalic patients improves diabetes and glucose metabolism. We aimed to determine the effect of pegvisomant, a GH receptor antagonist, on insulin resistance, endogenous glucose production (EGP) and lipolysis in insulin resistant non-diabetic men.  Methods: Four men between the ages of 18-62 with a BMI of 18-35kg/m (2), with insulin resistance as defined by a HOMA-IR > 2.77, were treated for four weeks with pegvisomant 20 mg daily...
2017: F1000Research
https://www.readbyqxmd.com/read/28694298/compound-specific-isotope-analysis-resolves-the-dietary-origin-of-docosahexaenoic-acid-dha-in-the-mouse-brain
#5
R J Scott Lacombe, Vanessa Giuliano, Stefanie M Colombo, Michael T Arts, Richard P Bazinet
Docosahexaenoic acid (DHA, 22:6n-3) may be derived from two dietary sources, preformed dietary DHA or through synthesis from α-linolenic acid (ALA, 18:3n-3). However, conventional methods cannot distinguish between DHA derived from either source without the use of costly labelled tracers. In the present study, we demonstrate the proof-of-concept that compound specific isotope analysis (CSIA) by gas chromatography-isotope ratio mass spectrometry (GC-IRMS) can differentiate between sources of brain DHA based on differences in natural (13)C enrichment...
July 10, 2017: Journal of Lipid Research
https://www.readbyqxmd.com/read/28674558/analysis-of-stable-isotope-assisted-metabolomics-data-acquired-by-high-resolution-mass-spectrometry
#6
X Wei, P K Lorkiewicz, B Shi, J K Salabei, B G Hill, S Kim, C J McClain, X Zhang
Stable isotope assisted metabolomics (SIAM) uses stable isotope tracers to support studies of biochemical mechanisms. We report a suite of data analysis algorithms for automatic analysis of SIAM data acquired on a high resolution mass spectrometer. To increase the accuracy of isotopologue assignment, metabolites detected in the unlabeled samples were used as reference metabolites to generate possible isotopologue candidates for analysis of peaks detected in the labeled samples. An iterative linear regression model was developed to deconvolute the overlapping isotopic peaks of isotopologues present in a full MS spectrum, where the threshold for the weight factor was determined by a simulation study assuming different levels of Gaussian white noise contamination...
April 21, 2017: Analytical Methods: Advancing Methods and Applications
https://www.readbyqxmd.com/read/28660919/solid-matrix-transformation-and-tracer-addition-using-molten-ammonium-bifluoride-salt-as-a-sample-preparation-method-for-laser-ablation-inductively-coupled-plasma-mass-spectrometry
#7
Jay W Grate, Jhanis J Gonzalez, Matthew J O'Hara, Cynthia M Kellogg, Samuel S Morrison, David W Koppenaal, George C-Y Chan, Xianglei Mao, Vassilia Zorba, Richard E Russo
Solid sampling and analysis methods, such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), are challenged by matrix effects and calibration difficulties. Matrix-matched standards for external calibration are seldom available and it is difficult to distribute spikes evenly into a solid matrix as internal standards. While isotopic ratios of the same element can be measured to high precision, matrix-dependent effects in the sampling and analysis process frustrate accurate quantification and elemental ratio determinations...
June 29, 2017: Analyst
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
#8
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/28622800/analysis-of-stable-isotope-assisted-metabolomics-data-acquired-by-gc-ms
#9
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/28596540/preparation-and-in-vivo-characterization-of-51-mncl2-as-pet-tracer-of-ca-2-channel-mediated-transport
#10
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/28584941/-trophic-and-source-amino-acids-in-trophic-estimation-a-likely-metabolic-explanation
#11
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/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/28544885/overcoming-interference-with-the-detection-of-a-stable-isotopically-labeled-microtracer-in-the-evaluation-of-beclabuvir-absolute-bioavailability-using-a-concomitant-microtracer-approach
#13
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...
September 5, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28515163/assessment-of-nitric-oxide-production-in-mitochondrial-encephalomyopathy-lactic-acidosis-and-stroke-like-episodes-syndrome-with-the-use-of-a-stable-isotope-tracer-infusion-technique
#14
REVIEW
Ayman W El-Hattab, Farook Jahoor
Mitochondrial disorders result from dysfunctional mitochondria that are unable to generate sufficient energy to meet the needs of various organs. Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is one of the most frequent maternally inherited mitochondrial disorders. There is growing evidence that nitric oxide (NO) deficiency occurs in MELAS syndrome and results in impaired blood perfusion that contributes significantly to several complications in this disease. NO is synthesized from arginine by NO synthase, which catalyzes the conversion of arginine to NO and citrulline...
May 17, 2017: Journal of Nutrition
https://www.readbyqxmd.com/read/28467082/novel-method-for-nitrogen-isotopic-analysis-of-soil-emitted-nitric-oxide
#15
Zhongjie Yu, Emily M Elliott
The global inventory of NOx (NOx = NO + NO2) emissions is poorly constrained, with a large portion of the uncertainty attributed to soil NO emissions that result from soil abiotic and microbial processes. While natural abundance stable N isotopes (δ(15)N) in various soil N-containing compounds have proven to be a robust tracer of soil N cycling, soil δ(15)N-NO is rarely quantified due to the measurement difficulties. Here, we present a new method that collects soil-emitted NO through NO conversion to NO2 in excess ozone (O3) and subsequent NO2 collection in a 20% triethanolamine (TEA) solution as nitrite and nitrate for δ(15)N analysis using the denitrifier method...
June 6, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28458168/a-rapid-method-for-estimation-of-pu-isotopes-in-urine-samples-using-high-volume-centrifuge
#16
Ranjeet Kumar, D D Rao, Rupali Dubla, J R Yadav
The conventional radio-analytical technique used for estimation of Pu-isotopes in urine samples involves anion exchange/TEVA column separation followed by alpha spectrometry. This sequence of analysis consumes nearly 3-4 days for completion. Many a times excreta analysis results are required urgently, particularly under repeat and incidental/emergency situations. Therefore, there is need to reduce the analysis time for the estimation of Pu-isotopes in bioassay samples. This paper gives the details of standardization of a rapid method for estimation of Pu-isotopes in urine samples using multi-purpose centrifuge, TEVA resin followed by alpha spectrometry...
July 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28424261/zinc-absorption-from-milk-is-affected-by-dilution-but-not-by-thermal-processing-and-milk-enhances-absorption-of-zinc-from-high-phytate-rice-in-young-dutch-women
#17
RANDOMIZED CONTROLLED TRIAL
Elise F Talsma, Diego Moretti, Sou Chheng Ly, Renske Dekkers, Ellen Ghm van den Heuvel, Aditia Fitri, Esther Boelsma, Tjeerd Jan Stomph, Christophe Zeder, Alida Melse-Boonstra
Background: Milk has been suggested to increase zinc absorption. The effect of processing and the ability of milk to enhance zinc absorption from other foods has not been measured directly in humans.Objective: We aimed to assess zinc absorption from 1) milk undergoing various processing and preparatory steps and 2) from intrinsically labeled high-phytate rice consumed with milk or water.Methods: Two randomized crossover studies were conducted in healthy young women [age:18-25 y; body mass index (in kg/m(2)): 20-25]: 1) a milk study (n = 19) comparing the consumption of 800 mL full-fat ultra-high temperature (UHT) milk [heat-treated milk (HTM)], full-fat UHT milk diluted 1:1 with water [heat-treated milk and water (MW)], water, or unprocessed (raw) milk (UM), each extrinsically labeled with (67)Zn, and 2) a rice study (n = 18) comparing the consumption of 90 g intrinsically (67)Zn-labeled rice with 600 mL of water [rice and water (RW)] or full-fat UHT milk [rice and milk (RM)]...
June 2017: Journal of Nutrition
https://www.readbyqxmd.com/read/28412769/applicability-of-geochemical-techniques-and-artificial-sweeteners-in-discriminating-the-anthropogenic-sources-of-chloride-in-shallow-groundwater-north-of-toronto-canada
#18
Esmaeil Khazaei, William Milne-Home
Elevated levels of chloride concentration due to anthropogenic activities including the road salts, septic effluent and agricultural sources are common in shallow groundwater of the recent glacial deposits north of Toronto, Ontario, Canada. Identifying suitable techniques for discriminating the source of the chloride concentration helps to better plan the protection of groundwater in the area. This paper examines the applicability of geochemical techniques with emphasis on Panno et al. (Ground Water 44: 176-187, 2006) and Mullaney et al...
May 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28402627/strategy-for-the-quantitation-of-a-protein-conjugate-via-hybrid-immunocapture-liquid-chromatography-with-sequential-hrms-and-srm-based-lc-ms-ms-analyses
#19
Yue Zhao, Guowen Liu, Xiling Yuan, Jinping Gan, Jon E Peterson, Jim X Shen
With the development of modern instrumentation and technologies, mass spectrometry based assays have played an important role in protein bioanalysis. We have developed a novel strategy by combining the "bottom-up" and "top-down" approaches using both high-resolution (HRMS) and selected reaction monitoring (SRM) based mass spectrometric detection to quantify a positron emission tomography (PET) detection tracer for an oncology marker. Monkey plasma samples were processed by immunocapture purification, followed by liquid chromatography (LC) with HRMS full scan analysis...
April 21, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28399577/drug-development-concepts-as-guides-for-optimizing-clinical-trials-of-supplemental-zinc-for-populations-at-risk-of-deficiency-or-diarrhea
#20
David H Alpers, Graeme P Young, Cuong D Tran, Elissa K Mortimer, Geetha L Gopalsamy, Nancy F Krebs, Mark J Manary, Balakrishnan S Ramakrishna, Henry J Binder, Ian L Brown, Leland V Miller
Studies on the efficacy of zinc supplementation for treatment or prevention of diarrhea have shown an inconsistent effect in populations at risk for zinc deficiency. Unlike drugs, which have no preexisting presence in the body, endogenous zinc must be assessed pharmacokinetically by isotope tracer studies. Although such methods have produced much data, very few studies have estimated the dose and the timing of dosing of zinc supplementation. This review examines drug kinetics used to establish the best dose, the timing of such doses, and the mechanism of action through pharmacodynamic markers and applies them, where possible, to zinc supplements...
March 1, 2017: Nutrition Reviews
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