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https://www.readbyqxmd.com/read/29771297/measurement-of-protein-digestibility-in-humans-by-a-dual-tracer-method
#1
Sarita Devi, Aneesia Varkey, M S Sheshshayee, Thomas Preston, Anura V Kurpad
Background: Recent evaluations of the risk of dietary protein deficiency have indicated that protein digestibility may be a key limiting factor in the provision of indispensable amino acids (IAAs), particularly for vulnerable populations living in challenging environments where intestinal dysfunction may exist. Since the digestion of protein occurs only in the small intestine, and the metabolic activity of colonic bacteria confounds measurements at the fecal level, there is a need to develop noninvasive protein digestibility measurements at the ileal level...
May 15, 2018: American Journal of Clinical Nutrition
https://www.readbyqxmd.com/read/29761430/gas-chromatography-mass-spectrometry-based-13-c-labeling-studies-in-plant-metabolomics
#2
Valéria F Lima, Leonardo Perez de Souza, Thomas C R Williams, Alisdair R Fernie, Danilo M Daloso
Stable-isotope labeling analysis has been used to discover new metabolic pathways and their key regulatory points in a wide range of organisms. Given the complexity of the plant metabolic network, this analysis provides information complementary to that obtained from metabolite profiling that can be used to understand how plants cope with adverse conditions, and how metabolism varies between different cells, tissues, and organs. Here we describe the experimental procedures from sample harvesting and extraction to mass spectral analysis and interpretation that allow the researcher to perform 13 C-labeling experiments...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29760108/anatomy-of-a-glacial-meltwater-discharge-event-in-an-antarctic-cove
#3
Michael P Meredith, Ulrike Falk, Anna Valeria Bers, Andreas Mackensen, Irene R Schloss, Eduardo Ruiz Barlett, Kerstin Jerosch, Adrián Silva Busso, Doris Abele
Glacial meltwater discharge from Antarctica is a key influence on the marine environment, impacting ocean circulation, sea level and productivity of the pelagic and benthic ecosystems. The responses elicited depend strongly on the characteristics of the meltwater releases, including timing, spatial structure and geochemical composition. Here we use isotopic tracers to reveal the time-varying pattern of meltwater during a discharge event from the Fourcade Glacier into Potter Cove, northern Antarctic Peninsula...
June 28, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29751316/stable-isotope-insights-into-the-weathering-processes-of-a-phosphogypsum-disposal-area
#4
Evgenia-Maria Papaslioti, Rafael Pérez-López, Annika Parviainen, Francisco Macías, Antonio Delgado-Huertas, Carlos J Garrido, Claudio Marchesi, José M Nieto
Highly acidic phosphogypsum wastes with elevated potential for contaminant leaching are stack-piled near coastal areas worldwide, threatening the adjacent environment. Huge phosphogypsum stacks were disposed directly on the marshes of the Estuary of Huelva (SW Spain) without any impermeable barrier to prevent leaching and thus, contributing to the total contamination of the estuarine environment. According to the previous weathering model, the process water ponded on the surface of the stack, initially used to carry the waste, was thought to be the main washing agent through its infiltration and subsequently the main component of the leachates emerging as the edge outflows...
April 28, 2018: Water Research
https://www.readbyqxmd.com/read/29751311/community-managed-forests-dominate-the-catchment-sediment-cascade-in-the-mid-hills-of-nepal-a-compound-specific-stable-isotope-analysis
#5
Hari Ram Upadhayay, Hugh G Smith, Marco Griepentrog, Samuel Bodé, Roshan Man Bajracharya, William Blake, Wim Cornelis, Pascal Boeckx
Soil erosion by water is critical for soil, lake and reservoir degradation in the mid-hills of Nepal. Identification of the nature and relative contribution of sediment sources in rivers is important to mitigate water erosion within catchments and siltation problems in lakes and reservoirs. We estimated the relative contribution of land uses (i.e. sources) to suspended and streambed sediments in the Chitlang catchment using stable carbon isotope signature (δ13 C) of long-chain fatty acids as a tracer input for MixSIAR, a Bayesian mixing model used to apportion sediment sources...
May 8, 2018: Science of the Total Environment
https://www.readbyqxmd.com/read/29747035/microscale-radiosynthesis-preclinical-imaging-and-dosimetry-study-of-18-f-ambf-3-tate-a-potential-pet-tracer-for-clinical-imaging-of-somatostatin-receptors
#6
Ksenia Lisova, Maxim Sergeev, Susan Evans-Axelsson, Andreea D Stuparu, Seval Beykan, Jeffrey Collins, Jason Jones, Michael Lassmann, Ken Herrmann, David Perrin, Jason T Lee, Roger Slavik, R Michael van Dam
BACKGROUND: Peptides labeled with positron-emitting isotopes are emerging as a versatile class of compounds for the development of highly specific, targeted imaging agents for diagnostic imaging via positron-emission tomography (PET) and for precision medicine via theranostic applications. Despite the success of peptides labeled with gallium-68 (for imaging) or lutetium-177 (for therapy) in the clinical management of patients with neuroendocrine tumors or prostate cancer, there are significant advantages of using fluorine-18 for imaging...
April 20, 2018: Nuclear Medicine and Biology
https://www.readbyqxmd.com/read/29729624/historical-records-distributions-and-sources-of-mercury-and-zinc-in-sediments-of-east-china-sea-implication-from-stable-isotopic-compositions
#7
Rui Zhang, James Russell, Xin Xiao, Fan Zhang, Tiegang Li, Zhiyong Liu, Minglei Guan, Qi Han, Liya Shen, Yujie Shu
The distribution and source of mercury (Hg) and zinc (Zn) in surface sediments from East China Sea (ECS) were studied using stable isotopes. Hg concentrations in surface sediments varied from 12.6 to 133.2 ng g-1 . Zn concentrations ranged between 45.9 and 133.6 ng g-1 . Hydrodynamic circulation and sedimentary process within the ECS were the dominant factors controlling the distribution and fate of heavy metals, referring from relationships of Hg and Zn concentrations and total organic carbon (TOC) and clay contents...
April 18, 2018: Chemosphere
https://www.readbyqxmd.com/read/29728518/dual-isotope-cryo-imaging-quantitative-autoradiography-ciqa-anvestigating-antibody-drug-conjugate-distribution-and-payload-delivery-through-imaging
#8
Ohad Ilovich, Mohammed Qutaish, Jacob Hesterman, Kelly Orcutt, Jack Hoppin, Ildiko Polyak, Marc Seaman, Adnan Abu-Yousif, Donna Cvet, Daniel Bradley
In vitro properties of antibody drug conjugates (ADCs) such as binding, internalization, and cytotoxicity are often well characterized prior to in vivo studies. Interpretation of in vivo studies could significantly be enhanced by molecular imaging tools. We present here a dual-isotope cryo-imaging quantitative autoradiography (CIQA) methodology combined with advanced 3D imaging and analysis allowing for the simultaneous study of both antibody and payload distribution in tissues of interest. in a pre-clinical setting...
May 4, 2018: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/29727671/metabolomics-and-isotope-tracing
#9
REVIEW
Cholsoon Jang, Li Chen, Joshua D Rabinowitz
Great strides have been made over the past decade toward comprehensive study of metabolism. Mass spectrometry (MS) has played a central role by enabling measurement of many metabolites simultaneously. Tracking metabolite labeling from stable isotope tracers can in addition reveal pathway activities. Here, we describe the basics of metabolite measurement by MS, including sample preparation, metabolomic analysis, and data interpretation. In addition, drawing on examples of successful experiments, we highlight the ways in which metabolomics and isotope tracing can illuminate biology...
May 3, 2018: Cell
https://www.readbyqxmd.com/read/29723161/metreleptin-improves-insulin-sensitivity-independent-of-food-intake-in-humans-with-lipodystrophy
#10
Rebecca J Brown, Areli Valencia, Megan Startzell, Elaine Cochran, Peter J Walter, H Martin Garraffo, Hongyi Cai, Ahmed M Gharib, Ronald Ouwerkerk, Amber B Courville, Shanna Bernstein, Robert J Brychta, Kong Y Chen, Mary Walter, Sungyoung Auh, Phillip Gorden
BACKGROUND: Recombinant leptin (metreleptin) ameliorates hyperphagia and metabolic abnormalities in leptin-deficient humans with lipodystrophy. We aimed to determine whether metreleptin improves glucose and lipid metabolism in humans when food intake is held constant. METHODS: Patients with lipodystrophy were hospitalized for 19 days with food intake held constant by controlled diet in an inpatient metabolic ward. In a non-randomized cross-over design, previously metreleptin-treated patients (n= 8) were continued on-metreleptin for five days, and off-metreleptin for the next 14 days (withdrawal cohort)...
May 3, 2018: Journal of Clinical Investigation
https://www.readbyqxmd.com/read/29721032/iron-physiological-requirements-in-chinese-adults-assessed-by-the-stable-isotope-labeling-technique
#11
Jie Cai, Tongxiang Ren, Yuhui Zhang, Zhilin Wang, Lingyan Gou, Zhengwu Huang, Jun Wang, Jianhua Piao, Xiaoguang Yang, Lichen Yang
Background: Iron is a kind of essential trace mineral in the human body, while the studies on its physiological requirement are very limited recently, especially in China. And most studies were performed with the radioisotope tracer technique, which was harmful to health. This study aimed to first get the value of iron physiological requirements in Chinese adults assessed by the stable isotope labeling technique. Methods: Forty-four eligible young Chinese healthy adults were randomly recruited from the Bethune Military Medical College (Shijiazhuang, Hebei, China) between January 2010 and March 2011, and 19 subjects were included in the final data analysis...
2018: Nutrition & Metabolism
https://www.readbyqxmd.com/read/29712983/stable-isotope-compositions-%C3%AE-2-h-%C3%AE-18-o-and-%C3%AE-17-o-of-rainfall-and-snowfall-in-the-central-united-states
#12
Chao Tian, Lixin Wang, Kudzai Farai Kaseke, Broxton W Bird
Stable isotopes of hydrogen and oxygen (δ2 H, δ18 O and δ17 O) can be used as natural tracers to improve our understanding of hydrological and meteorological processes. Studies of precipitation isotopes, especially 17 O-excess observations, are extremely limited in the mid-latitudes. To fill this knowledge gap, we measured δ2 H, δ18 O and δ17 O of event-based precipitation samples collected from Indianapolis, Indiana, USA over two years and investigated the influence of meteorological factors on precipitation isotope variations...
April 30, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29710847/groundwater-flow-processes-and-human-impact-along-the-arid-us-mexican-border-evidenced-by-environmental-tracers-the-case-of-tecate-baja-california
#13
Jürgen Mahlknecht, Luis Walter Daessle, Maria Vicenta Esteller, Juan Antonio Torres-Martinez, Abrahan Mora
With the increasing population, urbanization and industry in the arid area of Tecate, there is a concomitant increase in contaminants being introduced into the Tecate River and its aquifer. This contamination is damaging the usable groundwater supply and making local residents and commercial enterprises increasingly dependent on imported water from the Colorado River basin. In this study we apply a suite of chemical and isotopic tracers in order to evaluate groundwater flow and assess contamination trends. Groundwater recharge occurs through mountain-block and mountain-front recharge at higher elevations of the ranges...
April 30, 2018: International Journal of Environmental Research and Public Health
https://www.readbyqxmd.com/read/29702397/evaluation-of-thermokarst-lake-water-balance-in-the-qinghai-tibet-plateau-via-isotope-tracers
#14
Zeyong Gao, Fujun Niu, Zhanju Lin, Jing Luo, Guoan Yin, Yibo Wang
Thermokarst lakes are a ubiquitous landscape feature, which widely distributed in the pan-arctic and some low latitude regions, and are associated with regional hydrological processes. The studies were taken to obtain a better understanding of the water balance of thermokarst lakes in the Qinghai-Tibet Plateau (QTP) in order to gain insight of the regional hydrological cycle. The characteristics of the stable isotopes δ 18 O and δ D were investigated in precipitation, permafrost meltwater, and thermokarst lake water in the continuous permafrost region of the QTP and analyzed the lake water balance using the isotope mass model...
April 24, 2018: Science of the Total Environment
https://www.readbyqxmd.com/read/29695442/sterols-and-stanols-as-novel-tracers-of-waterbird-population-dynamics-in-freshwater-ponds
#15
Kathryn E Hargan, Emily M Stewart, Neal Michelutti, Christopher Grooms, Linda E Kimpe, Mark L Mallory, John P Smol, Jules M Blais
With the expansion of urban centres in the mid-twentieth century and the post-1970 decrease in pesticides, populations of double-crested cormorants ( Phalacrocorax auritus ) and ring-billed gulls ( Larus delawarensis ) around Lake Ontario (Canada and USA) have rapidly rebounded, possibly to unprecedented numbers. Along with the use of traditional palaeolimnological methods (e.g. stable isotopes, biological proxies), we now have the capacity to develop specific markers for directly tracking the presence of waterbirds on nesting islands...
April 25, 2018: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/29692688/one-step-18-f-labeling-of-estradiol-derivative-for-pet-imaging-of-breast-cancer
#16
Hongbo Huang, Ke Li, Gaochao Lv, Guiqing Liu, Xueyu Zhao, Qingzhu Liu, Shanshan Wang, Xi Li, Ling Qiu, Jianguo Lin
Positron emission tomography (PET) imaging is a useful method to evaluate in situ estrogen receptor (ER) status for the early diagnosis of breast cancer and optimization of the appropriate treatment strategy. The 18 F-labeled estradiol derivative has been successfully used to clinically assess the ER level of breast cancer. In order to simplify the radiosynthesis process, one-step 18 F-19 F isotope exchange reaction was employed for the 18 F-fluorination of the tracer of [ 18 F]AmBF 3 -TEG-ES . The radiotracer was obtained with the radiochemical yield (RCY) of ~61% and the radiochemical purity (RCP) of >98% within 40 min...
2018: Contrast Media & Molecular Imaging
https://www.readbyqxmd.com/read/29689484/preparation-of-mno-2-coated-fibers-for-gamma-spectrometric-measurements-a-comparison-of-four-practical-approaches
#17
Michael Schubert, Martin Oberreich, Jan Scholten
The analysis of natural radium-in-water activity concentrations is for two reasons of general interest: (1) radium in natural waters may pose a problem with regard to radiation protection and (2) radium isotopes in natural waters can be used as environmental tracers in hydrological studies. A state-of-the-art method for radium extraction from (generally large) water sample volumes is radium adsorption onto MnO2 coated acrylic fibers. In our study we comparatively evaluated four methodical approaches for post-extraction preparation of the fiber to allow gamma spectrometric measurements...
April 21, 2018: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/29685734/quantitative-analysis-of-nad-synthesis-breakdown-fluxes
#18
Ling Liu, Xiaoyang Su, William J Quinn, Sheng Hui, Kristin Krukenberg, David W Frederick, Philip Redpath, Le Zhan, Karthikeyani Chellappa, Eileen White, Marie Migaud, Timothy J Mitchison, Joseph A Baur, Joshua D Rabinowitz
The redox cofactor nicotinamide adenine dinucleotide (NAD) plays a central role in metabolism and is a substrate for signaling enzymes including poly-ADP-ribose-polymerases (PARPs) and sirtuins. NAD concentration falls during aging, which has triggered intense interest in strategies to boost NAD levels. A limitation in understanding NAD metabolism has been reliance on concentration measurements. Here, we present isotope-tracer methods for NAD flux quantitation. In cell lines, NAD was made from nicotinamide and consumed largely by PARPs and sirtuins...
April 20, 2018: Cell Metabolism
https://www.readbyqxmd.com/read/29679819/submarine-groundwater-discharge-and-chemical-behavior-of-tracers-in-laizhou-bay-china
#19
Yan Zhang, Hailong Li, Xuejing Wang, Chaoyue Wang, Kai Xiao, Wenjing Qu
Naturally occurring radon (222 Rn) and radium isotopes are widely used to trace water mixing and submarine groundwater discharge (SGD) in the coastal zones. However, their activities in groundwater are variable both spatially and temporally. Here, time series sampling of 222 Rn and radium was conducted to investigate their behavior in intertidal groundwater of Laizhou Bay, China. The result shows that groundwater redox conditions have an important impact on the behavior of tracers. The activities of tracers will decrease under oxidizing conditions and increase under reducing conditions...
April 18, 2018: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/29678110/experimental-evidence-for-in-situ-nitric-oxide-production-in-anaerobic-ammonia-oxidizing-bacterial-granules
#20
Rathnayake M L D Rathnayake, Mamoru Oshiki, Satoshi Ishii, Takahiro Segawa, Hisashi Satoh, Satoshi Okabe
Although nitric oxide (NO) emissions from anaerobic ammonium oxidation (anammox)-based processes were reported previously, the NO production pathways are poorly understood. Here, we investigated the NO production pathways in anammox granules in detail by combining 15 N-stable isotope tracer experiments with various inhibitors, microsensor measurements, and transcriptome analysis for key genes of NO2 - reduction. NO was emitted from the anammox granules, which account for 0.07% of the N2 emission. 15 N-stable isotope-tracer experiments indicated that most of the N2 was produced by anammox bacteria, whereas NO was produced from NO2 - reduction by anammox and denitrifying bacteria...
April 20, 2018: Environmental Science & Technology
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