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Isotope tracer

Ellen E Blaak
The obese insulin resistant and/or prediabetic state is characterised by systemic lipid overflow, mainly driven by an impaired lipid buffering capacity of adipose tissue, and an impaired capacity of skeletal muscle to increase fat oxidation upon increased supply. This leads to the accumulation of bioactive lipid metabolites in skeletal muscle interfering with insulin sensitivity via various mechanisms. In this review, the contribution of dietary v. endogenous fatty acids to lipid overflow, their extraction or uptake by skeletal muscle as well as the fractional synthetic rate, content and composition of the muscle lipid pools is discussed in relation to the development or presence of insulin resistance and/or an impaired glucose metabolism...
January 19, 2017: Proceedings of the Nutrition Society
Hsiou-Ting Kuo, Jinhe Pan, Joseph Lau, Chengcheng Zhang, Jutta Zeisler, Nadine Colpo, Francois Benard, Kuo-Shyan Lin
Peptide receptors have emerged as promising targets for diagnosis and therapy. The aberrant overexpression of these receptors in different cancer subtypes allows for the adoption of new treatment strategies that complement conventional chemotherapies. Bradykinin B1 receptor (B1R) is a G protein-coupled receptor that is overexpressed in many cancers, with limited expression in healthy tissues. Previously, we developed 68Ga- and 18F-labeled derivatives of B1R antagonist peptides B9858 and B9958, and successfully targeted B1R-expressing tumor xenografts in vivo...
January 17, 2017: Molecular Pharmaceutics
Carlijn T I de Betue, Xiomara C Garcia Casal, Dick A van Waardenburg, Stephen M Schexnayder, Koen F M Joosten, Nicolaas E P Deutz, Marielle P K J Engelen
BACKGROUND & AIMS: The reference method to study protein and arginine metabolism in critically ill children is measuring plasma amino acid appearances with stable isotopes during a short (4-8 h) time period and extrapolate results to 24-h. However, 24-h measurements may be variable due to critical illness related factors and a circadian rhythm could be present. Since only short duration stable isotope studies in critically ill children have been conducted before, the aim of this study was to investigate 24-h appearance of specific amino acids representing protein and arginine metabolism, with stable isotope techniques in continuously fed critically ill children...
January 4, 2017: Clinical Nutrition: Official Journal of the European Society of Parenteral and Enteral Nutrition
R Eigl, P Steier, K Sakata, A Sakaguchi
The first extensive study on (236)U in the North Pacific Ocean has been conducted. The vertical distribution of (236)U/(238)U isotopic ratios and the (236)U concentrations were analysed on seven depth profiles, and large variations with depth were found. The range of (236)U/(238)U isotopic ratios was from (0.09 ± 0.03) × 10(-10) to (14.1 ± 2.2) × 10(-10), which corresponds to (236)U concentrations of (0.69 ± 0.24) × 10(5) atoms/kg and (119 ± 21) × 10(5) atoms/kg, respectively. The variations in (236)U concentrations could mainly be attributed to the different water masses in the North Pacific Ocean and their formation processes...
January 12, 2017: Journal of Environmental Radioactivity
Louise Champoux, Jean-François Rail, Raphael A Lavoie
Northern gannet (Morus bassanus) eggs from Bonaventure Island, Québec, Canada, were collected to monitor concentrations of contaminants. Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) and non-ortho polychlorinated biphenyls (PCBs) were measured in eggs from 2004 and 2009, and several brominated and nonbrominated flame retardants (FRs) were measured every 2-5 years in eggs from 1994 to 2014. The sum (Σ) concentrations of PCDDs/Fs were significantly lower in 2009 relative to 2004, but the total toxic equivalent concentrations for PCDDs, PCDFs, and PCBs showed no significant differences (196 ng/kg wet weight (ww) in 2004 and 220 ng/kg ww in 2009)...
January 6, 2017: Environmental Pollution
J B Richardson
Manganese (Mn) cycling in the Critical Zone is important because of its role as an essential nutrient and potential toxicity to plants and organisms. Quantifying Mn enrichment in terrestrial environments has been limited since Mn is monoisotopic. However, elemental ratios of Mn/Ca ratios may be used to determine spatial Mn enrichment and in aboveground and belowground pools. The objectives of this study were to quantify the spatial variation in Mn concentrations and Mn/Ca ratios in foliage, bolewood, forest floor, and mineral soil horizons across the northeastern United States and compare Mn/Ca ratios to estimate enrichment...
January 2, 2017: Science of the Total Environment
Yihong Xu, Shaoming Pan, Mengmeng Wu, Kexin Zhang, Yongpei Hao
Information on how plutonium (Pu) isotopes associate with natural soil particles of different size is very important for the interpretation involved in the application of Pu isotopes as soil erosion tracers. This work investigated the association of Pu isotopes with different particle size fractions of natural soils and compared it with that of (137)Cs. Ten bulk soils collected from two different areas were separated into different particle size fractions by a combination of wet sieving and centrifugation techniques and the sub-samples were analyzed for (137)Cs, (239)Pu and (240)Pu...
January 2, 2017: Science of the Total Environment
Kerry McCarney-Castle, Tristan M Childress, Christian R Heaton
Many streams in the Piedmont region of the southeastern United States transport a disproportionately large amount of suspended sediment in response to moderately increased streamflows. Transport and deposition of excess sediment affect the stability of the channel and the health of the biological community; therefore, identifying the main source(s) of sediment and assessing the relationships between source, transport, and streamflow are critical to aquatic life and habitat management, dynamic equilibrium preservation, and development of feasible mitigation scenarios...
October 28, 2016: Journal of Environmental Management
Wen-Qian Chen, Wen-Xiong Wang, Qiao-Guo Tan
The effects of salinity on metal toxicity are complex: not only affecting metal bioaccumulation, but also altering the physiology and sensitivity of organisms. In this study, we used a toxicokinetic-toxicodynamic (TK-TD) model to separate and quantify the dual effects of salinity on copper (Cu) toxicity in a euryhaline clam Potamocorbula laevis. The toxicokinetics of Cu was determined using the stable isotope (65)Cu as a tracer at concentrations (10-500 μg L(-1)) realistic to contaminated environments and at salinities ranging from 5 to 30...
December 23, 2016: Environmental Pollution
Xiao Ying Gong, Rudi Schaeufele, Christoph Andreas Lehmeier, Guillaume Tcherkez, Hans Schnyder
Plant carbon-use-efficiency (CUE), a key parameter in carbon cycle and plant growth models, quantifies the fraction of fixed carbon that is converted into net primary production rather than respired. CUE has not been directly measured, partly due to the difficulty of measuring respiration in light. Here, we explore if CUE is affected by atmospheric CO2 . Sunflower stands were grown at low (200 µmol mol(-1) ) or high CO2 (1000 µmol mol(-1) ) in controlled-environment mesocosms. CUE of stands was measured by dynamic stand-scale (13) C labeling and partitioning of photosynthesis and respiration...
December 26, 2016: Plant, Cell & Environment
Vera Höllriegl, Wei Bo Li, Bernhard Michalke
Tracer kinetics in healthy human volunteers was studied applying stable isotopes of cerium citrate to obtain biokinetic human data for the urinary excretion of cerium. These data were then used to compare and validate the biokinetic model for lanthanides (cerium) proposed by Taylor and Leggett (Radiat Prot Dosim 105:193-198, 2003), which is substantially improved and more realistic than the biokinetic model currently recommended by the International Commission on Radiological Protection (ICRP Publication 67, 1993); both models are primarily based on animal data...
December 20, 2016: Radiation and Environmental Biophysics
Firas S Midani, Michelle L Wynn, Santiago Schnell
The use of isotopically labeled tracer substrates is an experimental approach for measuring in vivo and in vitro intracellular metabolic dynamics. Stable isotopes that alter the mass but not the chemical behavior of a molecule are commonly used in isotope tracer studies. Because stable isotopes of some atoms naturally occur at non-negligible abundances, it is important to account for the natural abundance of these isotopes when analyzing data from isotope labeling experiments. Specifically, a distinction must be made between isotopes introduced experimentally via an isotopically labeled tracer and the isotopes naturally present at the start of an experiment...
January 10, 2017: Analytical Biochemistry
Qi Tao, Radek Jupa, Jipeng Luo, Alexander Lux, Ján Kováč, Yue Wen, Yimei Zhou, Japenga Jan, Yongchao Liang, Tingqiang Li
Although the significance of apoplasmic barriers in roots with regards to the uptake of toxic elements is generally known, the contribution of apoplasmic bypasses (ABs) to cadmium (Cd) hyperaccumulation is little understood. Here, we employed a combination of stable isotopic tracer techniques, an ABs tracer, hydraulic measurements, suberin lamellae staining, metabolic inhibitors, and antitranspirants to investigate and quantify the impact of the ABs on translocation of Cd to the xylem in roots of a hyperaccumulating (H) ecotype and a non-hyperaccumulating (NH) ecotype of Sedum alfredii In the H ecotype, the Cd content in the xylem sap was proportional to hydrostatic pressure, which was attributed to pressure-driven flow via the ABs...
December 16, 2016: Journal of Experimental Botany
Muhammad Asim
Two patients with end-stage-renal-disease on continuous ambulatory peritoneal dialysis (CAPD) presented with pleural effusions. The aspirated fluid was categorised as transudate, based on alkaline pH, low protein and lactic dehydrogenase level. A striking feature of the pleural fluid was, its very high glucose content that resulted from translocation of dextrose containing peritoneal dialysate into the pleural space via a pleuroperitoneal connection. One patient was transferred to hemodialysis, which led to complete resolution of pleural effusion...
November 2016: Journal of the College of Physicians and Surgeons—Pakistan: JCPSP
Pedro L Aguado, M Dolores Curt, Helena Pereira, Jesús Fernández
The growth pattern of cork oak (Quercus suber L.), an important component of South Mediterranean woodlands, is seasonal. Seasonality has been found for shoot, radial and cork ring growth as well as for carbon (C) photoassimilation, nutrients remobilization and water relations, among other physiological aspects. However, little is known about the seasonality of C allocation to cork oak chemical compounds, including suberin, a major component of cork. In order to achieve this goal, an isotopic tracer experiment was conducted using 18-month-old cork oaks so that the fate of C photoassimilated in different seasons could be traced into biochemical (main organic) stem components...
December 14, 2016: Tree Physiology
Xinghui Xia, Zhimei Jia, Ting Liu, Sibo Zhang, Liwei Zhang
Suspended sediment (SPS) is ubiquitous in rivers, and SPS with different particle sizes and compositions may affect coupled nitrification-denitrification (CND) occurring on SPS significantly. However, there is no related research report. In this work, (15)N isotope tracer technique was adopted to explore the CND in systems containing SPS (8 g L(-1) and 1 g L(-1)) collected from the Yellow River with various particle sizes, including <2, 2-20, 20-50, 50-100, and 100-200 μm. The results showed that the CND occurred on SPS and the CND rate was negatively related to particle size; both nitrification and denitrification rate constants increased with decreasing SPS particle size...
January 3, 2017: Environmental Science & Technology
Agnieszka U Blachnio-Zabielska, Marta Chacinska, Mikkel H Vendelbo, Piotr Zabielski
BACKGROUND/AIMS: Muscle bioactive lipids accumulation leads to several disorder states. The most common are insulin resistance (IR) and type 2 diabetes. There is an ongoing debate which of the lipid species plays the major role in induction of muscle IR. Our aim was to elucidate the role of particular lipid group in induction of muscle IR. METHODS: The analyses were performed on muscle from the following groups of rats: 1. Control, fed standard diet, 2 HFD, fed high fat diet, 3...
2016: Cellular Physiology and Biochemistry
Xun Wang, Ji Luo, Runsheng Yin, Wei Yuan, Che-Jen Lin, Jonas Sommar, Xinbin Feng, Haiming Wang, Cynthia Lin
Mercury accumulation in montane forested areas plays an important role in global Hg cycling. In this study, we measured stable Hg isotopes in soil and litter samples to understand Hg accumulation on the forest floor along the eastern fringe of the Tibetan Plateau (TP). The low atmospheric Hg inputs lead to the small Hg pool size (23 ± 9 mg m(-2) in 0-60 cm soil horizon), up to 1 order of magnitude lower than those found at sites in Southwest China, North America, and Europe. The slightly negative Δ(199)Hg (-0...
December 23, 2016: Environmental Science & Technology
Gerald F Watts, Dick C Chan, Ricardo E Dent, Ransi Somaratne, Scott M Wasserman, Rob Scott, Sally Burrows, Peter Hugh R Barrett
BACKGROUND: -Monoclonal antibodies (mAbs) against proprotein convertase subtilisin kexin type 9 (PCSK9), such as evolocumab, lower plasma low-density lipoprotein (LDL)-cholesterol concentrations. Evolocumab is under investigation for its effects on cardiovascular outcomes in statin-treated, high-risk patients. The mechanism of action of PCSK9 mAbs on lipoprotein metabolism remains to be fully evaluated. Stable isotope tracer kinetics can effectively elucidate the mode of action of new lipid regulating pharmacotherapies...
December 9, 2016: Circulation
Matthew S Alkaitis, Honghui Wang, Allison K Ikeda, Carol A Rowley, Ian J C MacCormick, Jessica H Chertow, Oliver Billker, Anthony F Suffredini, David J Roberts, Terrie E Taylor, Karl B Seydel, Hans C Ackerman
BACKGROUND:  Plasmodium infection depletes arginine, the substrate for nitric oxide synthesis, and impairs endothelium-dependent vasodilation. Increased conversion of arginine to ornithine by parasites or host arginase is a proposed mechanism of arginine depletion. METHODS:  We used high-performance liquid chromatography to measure plasma arginine, ornithine, and citrulline levels in Malawian children with cerebral malaria and in mice infected with Plasmodium berghei ANKA with or without the arginase gene...
December 15, 2016: Journal of Infectious Diseases
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