Read by QxMD icon Read

isotopic tracer method

Antoinette Moran, Gianna Toffolo, Michele Schiavon, Adrian Vella, Katherine A Klaus, Claudio Cobelli, K Sreekumaran Nair
Insulin and nutrients have profound effects on proteome homeostasis. Currently no reliable methods are available to measure postprandial protein turnover. A triple tracer method was developed using phenylalanine stable isotope tracers to estimate appearance rates of ingested (Rameal ) and endogenous (Raend ) phenylalanine, and the rate of phenylalanine disposal (Rd). This was compared to the "traditional" dual tracer method, using one (1-CM) and two (2-CM) compartment models. For both methods, [13 C6 ]phenylalanine was given orally and [15 N]phenylalanine constantly infused; the triple tracer method added [2 H5 ]phenylalanine, infused at rates to mimic meal [13 C6 ]phenylalanine appearance...
June 5, 2018: American Journal of Physiology. Endocrinology and Metabolism
Roberta L Hansman, Marc Metian, Simon Pouil, François Oberhänsli, Jean-Louis Teyssié, Peter W Swarzenski
To better understand bioaccumulation of radiocaesium in the commercially important Japanese flatfish, Paralichthys olivaceus, the uptake and depuration kinetics of caesium via both seawater and food were assessed simultaneously using controlled aquaria. The pre-conditioned fish were exposed to radionuclides via the two different pathways (aqueous versus dietary) concurrently using two isotopes of caesium, 137 Cs and 134 Cs, respectively. Dissolved caesium uptake was linear and did not reach a steady state over the course of the 8-day exposure period...
October 2018: Journal of Environmental Radioactivity
Henning Schraknepper, Thomas E Weirich, Roger A De Souza
The existence of a polishing-induced damaged zone at the surface of standard, nominally undoped, single-crystal SrTiO3 is exploited in diffusion studies in order to investigate the interaction between oxygen vacancies and dislocations. Tracer diffusion profiles for such crystals are proposed to exhibit three features: a short feature arising from a surface space-charge layer; an intermediate, longer feature arising from the high density of dislocations in the damaged zone; and finally, a much longer feature corresponding to diffusion in the homogeneous bulk crystal...
May 25, 2018: Physical Chemistry Chemical Physics: PCCP
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
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
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
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
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
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...
September 2018: Journal of Environmental Radioactivity
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...
May 1, 2018: Cell Metabolism
Mahalakshmi Shankaran, Gregg Czerwieniec, Chancy Fessler, Po-Yin Anne Wong, Salena Killion, Scott M Turner, Marc K Hellerstein, William J Evans
BACKGROUND: Muscle mass can be measured directly in vivo by isotope dilution, using Creatine-(methyl-d3 ) monohydrate (D3 -Cr) by mouth followed by measurement of the steady-state enrichment of D3 -creatinine (D3 -Crn) in urine. Isotope dilution methods require knowledge of the amount of tracer delivered to the pool of interest. In a subset of human subjects, a small amount of orally administered D3 -Cr 'spills' into urine after absorption and prior to transport into skeletal muscle cells...
June 2018: Journal of Cachexia, Sarcopenia and Muscle
Ji-Hye Seo, Mukul Sharma, Erich C Osterberg, Brian P Jackson
Here we use two chemical separation procedures to determine exceptionally low Os concentrations (∼10-15 g g-1 ) and Os isotopic composition in polar snow/ice. Approximately 50 g of meltwater is spiked with 190 Os tracer solution and frozen at -20 °C in quartz-glass ampules. A mixture of H2 O2 and HNO3 is then added, and the sample is heated to 300 °C at 100 bar. This allows tracer Os to be equilibrated with the sample as all Os species are oxidized to OsO4 . The resulting OsO4 is separated using either distillation (Method-I) or solvent-extraction (Method-II), purified, and measured using negative thermal ionization mass spectrometry (N-TIMS)...
May 1, 2018: Analytical Chemistry
Zhengjian Yang, Bao Cheng, Yaqian Xu, Defu Liu, Jun Ma, Daobin Ji
Eutrophication has become a severe environmental problem in some tributaries of the Three Gorges Reservoir (TGR) in China. A two-year field investigation of nutrients, oxygen stable isotopes (δ18 O), and hydrogen stable isotopes (δD) was performed from January 2010 to December 2011 to determine the sources of nutrients in Xiangxi Bay (XXB). The results showed that nitrogen, phosphorus and silicon varied seasonally depending on hydrodynamic changes. The bottom-layer intrusive density current decreased nitrogen and silicon concentrations and increase phosphorus concentrations in XXB, while the middle-layer intrusive density current increased nitrogen and silicon concentrations and decrease phosphorus concentrations...
September 1, 2018: Science of the Total Environment
Anastasia Loktev, Thomas Lindner, Walter Mier, Jürgen Debus, Annette Altmann, Dirk Jäger, Frederik Giesel, Clemens Kratochwil, Philippe Barthe, Christian Roumestand, Uwe Haberkorn
The tumor stroma, which accounts for a large part of the tumor mass, represents an attractive target for the delivery of diagnostic and therapeutic compounds. Here, the focus is notably on a subpopulation of stromal cells, known as cancer-associated fibroblasts (CAFs), which are present in more than 90% of epithelial carcinomas including pancreatic, colon and breast cancer. CAFs feature a high expression of fibroblast activation protein (FAP), which is not detectable in adult normal tissue but associated with a poor prognosis in cancer patients...
April 6, 2018: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Lara Stephens-Brown, Michael Davis
BACKGROUND: Exercise increases water requirements, but there is little information regarding water loss in dogs performing multi-day exercise OBJECTIVES: Quantify the daily water turnover of working dogs during multi-day exercise and establish the suitability of SC administration of tracer to determine water turnover. ANIMALS: Fifteen privately owned Labrador retrievers trained for explosive detection duties and 16 privately owned Alaskan Huskies conditioned for mid-distance racing...
March 23, 2018: Journal of Veterinary Internal Medicine
Sonja Cerar, Kim Mezga, Gorazd Žibret, Janko Urbanc, Marko Komac
Groundwater is the most important source of drinking water in the world. Therefore, information on the quality and quantity is important, as is new information related to the characteristics of the aquifer and the recharge area. In the present study we focused on the isotope composition of oxygen (δ18 O) in groundwater, which is a natural tracer and provides a better understanding of the water cycle, in terms of origin, dynamics and interaction. The groundwater δ18 O at 83 locations over the entire Slovenian territory was studied...
August 1, 2018: Science of the Total Environment
Helena Banning, Monika Stelling, Stephan König, Ronny Schoenberg, Thomas Neumann
Selenium (Se) is an important micronutrient but also a strong toxin with a narrow tolerance range for many organisms. As such, a globally heterogeneous Se distribution in soils is responsible for various disease patterns (i.e. Se excess and deficiency) and environmental problems, whereby plants play a key role for the Se entrance into the biosphere. Selenium isotope variations were proved to be a powerful tracer for redox processes and are therefore promising for the exploration of the species dependent Se metabolism in plants and the Se cycling within the Critical Zone...
2018: PloS One
Ying Chen, Olga Berejnaia, Jinqi Liu, Sheng-Ping Wang, Natalie A Daurio, Wu Yin, Rafael Mayoral, Aleksandr Petrov, Takhar Kasumov, Guo-Fang Zhang, Stephen F Previs, David E Kelley, David G McLaren
Numerous studies have implicated dyslipidemia as a key factor in mediating insulin resistance. Ceramides have received special attention since their levels are inversely associated with normal insulin signaling and positively associated with factors that are involved in cardiometabolic disease. Despite the growing literature surrounding ceramide biology, there are limited data regarding the activity of ceramide synthesis and turnover in vivo. Herein, we demonstrate the ability to measure ceramide kinetics by coupling the administration of [2 H]water with LC-MS/MS analyses...
March 6, 2018: American Journal of Physiology. Endocrinology and Metabolism
Thomas Brendan Smith, Kamlesh Patel, Haydn Munford, Andrew Peet, Daniel A Tennant, Mark Jeeves, Christian Ludwig
Tracing the fate of stable isotopically-enriched nutrients is a sophisticated method of describing and quantifying the activity of metabolic pathways. Nuclear Magnetic Resonance (NMR) offers high resolution data, yet is under-utilised due to length of time required to collect the data, quantification requiring multiple samples and complicated analysis. Here we present two techniques, quantitative spectral filters and enhancement of the splitting due to J-coupling in 1 H, 13 C-HSQC NMR spectra, which allow the rapid collection of NMR data in a quantitative manner on a single sample...
2018: Wellcome Open Research
Eszter Boros, Omar R Pinkhasov, Peter Caravan
Background: Current analytical methods for characterizing pharmacokinetic and metabolic properties of positron emission tomography (PET) and single photon emission computed tomography (SPECT) probes are limited. Alternative methods to study tracer metabolism are needed. The study objective was to assess the potential of high performance liquid chromatography - inductively coupled plasma - mass spectrometry (HPLC-ICP-MS) for quantification of molecular probe metabolism and pharmacokinetics using stable isotopes...
2018: EJNMMI Radiopharmacy and Chemistry
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"