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Estimating protein turnover with a [15N,13C]leucine tracer: a study using simulated data. 1999

I J Gowrie, and A V Roudsari, and A M Umpleby, and R Hovorka
Centre for Measurement and Information of Medicine, City University, Northampton Square, London, EC1V 0HB, U.K.

We explore the use of [15N,13C]leucine tracer to estimate whole-body fractional rates of a fast-turning-over protein pool employing synthetic data. The kinetics of [15N,13C]leucine tracer are simplified compared with those of traditional leucine tracers and benefit from irreversible transamination to [13C]alpha-ketoisocaproaic acid (KIC) resulting in a simplified model structure. A three-compartment model of [15N,13C]leucine kinetics was proposed and evaluated using data generated by a Reference Model (based on a model by Cobelli et al.). The results suggest that fractional turnover rates of a fast-turning-over protein pool can be estimated with a low but acceptable precision during a six-hour constant intravenous infusion of [15N,13C]leucine with frequent sampling of plasma tracer-to-tracee ratio (TTR) of [15N,13C]leucine. We conclude that [15N,13C]leucine may be useful for the measurement of protein kinetics and its full potential should be explored in clinical studies with compartmental data analysis.

UI MeSH Term Description Entries
D007651 Keto Acids Carboxylic acids that contain a KETONE group. Oxo Acids,Oxoacids,Acids, Keto,Acids, Oxo
D007930 Leucine An essential branched-chain amino acid important for hemoglobin formation. L-Leucine,Leucine, L-Isomer,L-Isomer Leucine,Leucine, L Isomer
D008954 Models, Biological Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment. Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D009587 Nitrogen Isotopes Stable nitrogen atoms that have the same atomic number as the element nitrogen but differ in atomic weight. N-15 is a stable nitrogen isotope. Nitrogen Isotope,Isotope, Nitrogen,Isotopes, Nitrogen
D011506 Proteins Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein. Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D002247 Carbon Isotopes Stable carbon atoms that have the same atomic number as the element carbon but differ in atomic weight. C-13 is a stable carbon isotope. Carbon Isotope,Isotope, Carbon,Isotopes, Carbon
D003198 Computer Simulation Computer-based representation of physical systems and phenomena such as chemical processes. Computational Modeling,Computational Modelling,Computer Models,In silico Modeling,In silico Models,In silico Simulation,Models, Computer,Computerized Models,Computer Model,Computer Simulations,Computerized Model,In silico Model,Model, Computer,Model, Computerized,Model, In silico,Modeling, Computational,Modeling, In silico,Modelling, Computational,Simulation, Computer,Simulation, In silico,Simulations, Computer
D005215 Fasting Abstaining from FOOD. Hunger Strike,Hunger Strikes,Strike, Hunger,Strikes, Hunger
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man

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