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Double Barrel Glucagon Test: Correlation With Enzyme Assays in Limit Dextrinosis

Double Barrel Glucagon Test: Correlation With Enzyme Assays in Limit Dextrinosis Abstract STRUCTURALLY, glycogen is a complex branched molecule composed of glucosyl units.1 The branching points are formed by 1,6-bonds, while all other glucosyl units are attached by 1,4-bonds. Liver phosphorylase, an enzyme activated by glucagon, splits the 1,4-bonds, releasing glucose-1-phosphate. This, in turn, is metabolized to glucose-6-phosphate and then to glucose. The debrancher enzyme (amylo-1,6-glucosidase) splits the 1,6-bonds; if this enzyme is deficient, the degradation of glycogen will cease at the branching points. Theoretically, a 14-hour fast in a patient with debrancher enzyme deficiency, type 3 glycogen storage disease by Cori's classification,1 would be associated with the degradation of the outer branches of glycogen by liver phosphorylase to the points of 1,6-bonds; glucagon administration to such a patient would not result in a hyperglycemic response. If, however, such a patient were fasted for 14 hours and then fed a regular meal, outer branches might be resynthesized sufficiently so References 1. Cori, G. T.: Glycogen Structure and Enzyme Deficiencies in Glycogen Storage Disease , Harvey Lect 48:145-171, 1954. 2. Hug, G.: Glucagon Tolerance in Glycogen Storage Disease , J Pediat 60:545, 1962.Crossref 3. Hug, G., et al: Cori's Disease (Amylo-1,6-Glucosidase Deficiency): Report of Case in Negro Child , New Eng J Med 268:113, 1963.Crossref 4. Kaye, R., et al: Response of Blood Glucose, Ketones, and Plasma Nonesterified Fatty Acids to Fasting and Epinephrine Injection in Infants and Children , J Pediat 59:836, 1961.Crossref 5. Vassella, F.: Die Glucagonbelastungsprobe beim gesunden Kind , Helv Paediat Acta 12:331, 1957. 6. Illingworth, B., and Brown, D. H.: Action of Amylo-1, 6-Glucosidase on Low Molecular Weight Substrates and Assay of This Enzyme in Glycogen Storage Disease , Proc Nat Acad Sci USA 48:1619, 1962.Crossref 7. Hers, H. G.: Advances in Metabolic Disorders , New York: Academic Press, Inc., 1964, vol 1, pp 1-44. 8. O'Brien, D., and Ibbott, F. A., ed.: Laboratory Manual of Pediatric Micro- and Ultramicro-Biochemical Techniques , New York: Paul E. Hoeber, Inc., Medical Book Dept. of Harper & Row, Publishers, Inc., 1962, p 134. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png American Journal of Diseases of Children American Medical Association

Double Barrel Glucagon Test: Correlation With Enzyme Assays in Limit Dextrinosis

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References (9)

Publisher
American Medical Association
Copyright
Copyright © 1965 American Medical Association. All Rights Reserved.
ISSN
0002-922X
DOI
10.1001/archpedi.1965.02090020164014
Publisher site
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Abstract

Abstract STRUCTURALLY, glycogen is a complex branched molecule composed of glucosyl units.1 The branching points are formed by 1,6-bonds, while all other glucosyl units are attached by 1,4-bonds. Liver phosphorylase, an enzyme activated by glucagon, splits the 1,4-bonds, releasing glucose-1-phosphate. This, in turn, is metabolized to glucose-6-phosphate and then to glucose. The debrancher enzyme (amylo-1,6-glucosidase) splits the 1,6-bonds; if this enzyme is deficient, the degradation of glycogen will cease at the branching points. Theoretically, a 14-hour fast in a patient with debrancher enzyme deficiency, type 3 glycogen storage disease by Cori's classification,1 would be associated with the degradation of the outer branches of glycogen by liver phosphorylase to the points of 1,6-bonds; glucagon administration to such a patient would not result in a hyperglycemic response. If, however, such a patient were fasted for 14 hours and then fed a regular meal, outer branches might be resynthesized sufficiently so References 1. Cori, G. T.: Glycogen Structure and Enzyme Deficiencies in Glycogen Storage Disease , Harvey Lect 48:145-171, 1954. 2. Hug, G.: Glucagon Tolerance in Glycogen Storage Disease , J Pediat 60:545, 1962.Crossref 3. Hug, G., et al: Cori's Disease (Amylo-1,6-Glucosidase Deficiency): Report of Case in Negro Child , New Eng J Med 268:113, 1963.Crossref 4. Kaye, R., et al: Response of Blood Glucose, Ketones, and Plasma Nonesterified Fatty Acids to Fasting and Epinephrine Injection in Infants and Children , J Pediat 59:836, 1961.Crossref 5. Vassella, F.: Die Glucagonbelastungsprobe beim gesunden Kind , Helv Paediat Acta 12:331, 1957. 6. Illingworth, B., and Brown, D. H.: Action of Amylo-1, 6-Glucosidase on Low Molecular Weight Substrates and Assay of This Enzyme in Glycogen Storage Disease , Proc Nat Acad Sci USA 48:1619, 1962.Crossref 7. Hers, H. G.: Advances in Metabolic Disorders , New York: Academic Press, Inc., 1964, vol 1, pp 1-44. 8. O'Brien, D., and Ibbott, F. A., ed.: Laboratory Manual of Pediatric Micro- and Ultramicro-Biochemical Techniques , New York: Paul E. Hoeber, Inc., Medical Book Dept. of Harper & Row, Publishers, Inc., 1962, p 134.

Journal

American Journal of Diseases of Children – American Medical Association

Published: Feb 1, 1965

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