Emerging Technologies for Nutrition Research Potential for Assessing Military Performance Capability (1997) / Chapter Skim
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Emerging Technologies for Nutrition Research, 1997 Pp.
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muscle glycogen synthesis. Finally, this paper will discuss the utilization of 13C NMR spectroscopy in the noninvasive measurement of hepatic glycogen content for direct quantification of hepatic glycogenolysis and indirect quantification of gluconeogenesis in normal subjects and subjects with Type II diabetes mellitus.
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nucleus to examine using NMR spectroscopy. It is the signals from protons in the body that are analyzed when whole-body magnetic resonance imaging (MRI)
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measure tissue metabolite concentration noninvasively makes NMR spectroscopy a very powerful technique for clinical investigation. Applications of NMR Spectroscopy NMR spectroscopy is a useful tool that has contributed to the better understanding of some of the basic pathophysiologic events that occur in Type II diabetes.
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Figure 11-1 Incremental change in muscle glycogen concentration in both Type II diabetic subjects (NIDDM) and age-and weight-matched control subjects during a hyperglycemic-hyperinsulinemic clamp.
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synthetic pathway is largely responsible for the slower rates of glucose disposal in patients with Type II diabetes mellitus. GLUCOSE TRANSPORT-PHOSPHORYLATION: THE RATELIMITING STEP IN MUSCLE GLYCOGEN SYNTHESIS In order to identify and understand the defect in the conversion of glucose to muscle glycogen in Type II diabetes, it is necessary to consider the two wellrecognized steps in muscle glycogen synthesis that are insulin regulated and might be affected in patients with Type II diabetes mellitus.
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Figure 11-3 Glucose-6-phosphate (G-6-P) concentration during the hyperglycemic-hyperinsulinemic clamp study in both Type II diabetic subjects (NIDDM)
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NMR SPECTROSCOPIC STUDIES OF LIVER GLYCOGEN METABOLISM The application of NMR spectroscopy to the measurement of liver glycogen also has resulted in many significant new observations, as liver tissue is even more inaccessible than muscle tissue for biopsy. In one study that made use of the naturally occurring 13C in liver glycogen, 13C NMR spectroscopy was used to measure the net rate of hepatic glycogenolysis during a 68-h fast in seven young healthy subjects (Rothman et al., 1991)
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Figure 11-5 Mean rates of whole-body glucose production, net hepatic glycogenolysis, and gluconeogenesis in young normal subjects for three intervals (0 to 22 hours, 22 to 46 hours, and 46 to 64 hours) during a 68-h fast.
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Figure 11-6 Hepatic glycogen concentration time course in both Type II diabetic subjects (NIDDM) and age-and weight-matched control subjects following an overnight fast.
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Figure 11-7 Mean rates of whole-body glucose production, net hepatic glycogenolysis and gluconeogenesis in both Type II diabetic subjects and ageand weight-matched control subjects following an overnight fast.
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as well as the development of magnets with higher field strengths, it likely will be possible to improve considerably on the overall sensitivity of this technique in the near future. AUTHOR'S SUMMARY In summary, NMR spectroscopy has become a useful tool for investigating the physiologic regulation of liver and muscle glycogen metabolism in normal humans as well as defining the metabolic defects that occur in patients with Type II diabetes mellitus.
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Denton, R.M., and J.M. Tavaré 1992 Action of insulin on intracellular processes.
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ROBERT NESHEIM: Thank you very much, that was very interesting. I cannot help but be struck by the fact that 50 years ago when I was in the Army, I do not recall that we were talking about any of these subjects.
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