University of Texas System

Craig R Malloy

A Dean Sherry

John Griffith Jones

John G Jones

Navin Bansal

G Larry Cottam

F Mark Jeffrey

F M H Jeffrey

Piyu Zhao

The present invention provides a combination of carbon-13 and deuterium metabolic tracers and methods that when used in conjunction with nuclear magnetic resonance spectroscopy, provide a measurement of metabolic fluxes in the target organisms. The tracers of the present invention may be taken orally during the same clinical exam. The metabolic information can be derived from blood, urine or other fluids to provide a comprehensive profile of glucogenic metabolism. The subject matter of the present invention may be applied to the study of metabolic dysfunction related to obesity, diabetes, HIV infection and a variety of other disease conditions.

Measurement of gluconeogenesis and intermediary metabolism using stable isotopes

Simple equations that relate glucose, glutamate, glucuronate, and phenylacetylglutamine,C NMR multiplet areas to gluconeogenesis and pyruvate recycling during metabolism of &lsqb;1,2,3-,C,&rsqb;propionate are presented. This indicates that a direct measure of gluconeogenesis, pyruvate recycling, and anaplerosis may be obtained from a single,C NMR spectrum of suitably prepared blood or urine samples collected after oral administration of enriched propionate, acetaminophen, and phenylacetate.

Methods for determining gluconeogenesis, anapleurosis and pyruvate recycling

New methods for rapid, noninvasive determination of sodium ion in vivo are described. The methods are useful for assessing liver and other organ injury based on a nuclear magnetic resonance determination of intracellular and extracellular sodium in the damaged tissue. A shift reagent, TmDOTP.sup.5-, is used in vivo to produce baseline resolved peaks of .sup.23 Na. Excellent results are achieved with significantly less TmDOTP.sup.5- than with other conventional .sup.23 Na shift reagents such as DyTTHA.sup.3-. In contrast to use in isolated perfused heart tissue, TmDOTP.sup.5- solutions are employed in vivo without added calcium ion. The method has been applied to animal burn models. Results show that intracellular sodium ion levels are dramatically increased, thus providing a rapid assessment of liver function. Similar methods may be applied to the determination of intra- and extracellular potassium ion.

Determination of intracellular sodium and potassium ions by NMR

Entry of .sup.13 C-enriched acetyl-CoA into the citric acid cycle results in scrambling of .sup.13 C into the various carbon positions of all intermediate pools. The eventual result is that the .sup.13 C resonances of all detectable intermediates or molecules exchanging with those intermediates appear as multiplets due to nearest neighbor spin-spin couplings. Isotopomer analysis of the glutamate .sup.13 C multiplets provides a history of .sup.13 C flow through the cycle pools. Relative substrate utilization and relative anaplerotic flux can be quantitated. A major limitation of the method for in vivo applications is spectral resolution of multi-line resonances required for a complete isotopomer analysis. It is now shown that (.sup.13 C)homonuclear decoupling of the glutamate C3 resonance collapses nine-line C4 and C2 resonances into three line multiplets. These three-line .sup.13 C multiplets are well resolved in isolated, perfused rat hearts and present steady-state equations which allow an isotopomer analysis from data obtained in intact tissue. This advancement shows for the first time that .sup.13 C isotopomer methods may be extended to complex metabolic conditions for resolution of carbon-carbon coupling, and particularly to in vivo measurements.

.sup.13 C Isotopomer analyses in intact tissue using (.sup.13 C)

The present invention relates to a method of measuring the contribution of one or more exogenously administered .sup.13 C-labeled substrates to acetyl-CoA. The measurement can be made in a tissue or cell using .sup.13 C NMR without the constraint of metabolic or isotopic steady-state. Furthermore, the method permits the determination even when spectral lines are broad due to B.sub.0 inhomogeneity, thereby opening the way for substrate utilization studies in vivo. The method does not require many of the simplifying assumptions involved in .sup.11 C or .sup.14 C methods, and, since a stable isotope, .sup.13 C, is used a wide variety of compounds with complex labeling patterns may be synthesized and studied.

Growing community of inventors

Dallas, TX, United States of America

Craig R Malloy