Clinical Biochemistry of Domestic Animals PDF
Preview Clinical Biochemistry of Domestic Animals
Contributors J. C. Bartley D. F. Brobst Charles Ε. Cornelius George T. Dimopoullos J. J. Kaneko Mogens G. Simesen John S. Wilkinson CLINICAL BIOCHEMISTRY OF OOMESTIC ANIMALS Second Edition VOLUME I Edited by J. J. KANEKO Department of Clinical Pathology University of California Davis, California and C. E. CORNELIUS Department of Physiological Sciences Kansas State University Manhattan, Kansas ACADEMIC PRESS 1970 New York and London COPYRIGHT © 1970, BY ACADEMIC PRESS, INC. ALL RIGHTS RESERVED NO PART OF THIS BOOK MAY BE REPRODUCED IN ANY FORM, BY PHOTOSTAT, MICROFILM, RETRIEVAL SYSTEM, OR ANY OTHER MEANS, WITHOUT WRITTEN PERMISSION FROM THE PUBLISHERS. ACADEMIC PRESS, INC. Ill Fifth Avenue, New York, New York 10003 United Kingdom Edition published b\ ACADEMIC PRESS, INC. (LONDON) LTD. Berkeley Square House, London WIX 6BA LIBRARY OF CONGRESS CATALOG CARD NUMBER: 72-117089 PRINTED IN THE UNITED STATES OF AMERICA List of Contributors Numbers in parentheses indicate the pages on which the authors' contributions begin. J. C. Bartley (53), Bruce Lyon Memorial Research Laboratory, Children's Hospital Medical Center of Northern California, Oakland, California D. F. Brobst* (231), Department of Veterinary Microbiology, Pathology and Public Health, Purdue University, Lafayette, Indiana Charles E. Cornelius (161), Department of Physiological Sciences, Kansas State University, Manhattan, Kansas George T. DImopoullos (97), Department of Veterinary Science, Agricultural Experiment Station, Louisiana State University, Baton Rouge, Louisiana J. J. Kaneko (1, 131, 293, 377), Department of Clinical Pathology, University of California, Davis, California Mogens G. SImesen (313), Department of Special Pathology and Therapeutics, Royal Veterinary and Agricultural University, Copenhagen, Denmark John S. Wilkinson (247), Department of Veterinary Clinical Pathology, School of Veterinary Science, University of Melbourne, Australia * Present address: Department of Veterinary Clinical Medicine and Surgery, Washington State University, Pullman, Washington Preface to the Second Edition The marked expansion of knowledge in the clinical biochemistry of animals since publication of the first edition of this book seven years ago has necessitated this major revision. In this period, a wealth of new information on clinical bio chemical aspects of disease in animals has become available. This has been made possible by the continued rapid advances of modern biochemistry, the increasing awareness of the usefulness of animal models of human disease in biomedical research, and the ever increasing growth of both veterinary and human medicine. In keeping with this expansion of knowledge, this edition is coniprised of two volumes. Chapters on the pancreas, thyroid, and pituitary-adrenal systems have been separated and entirely rewritten. Completely new chapters on muscle meta bolism, iron metabolism, blood clotting, and gastrointestinal function have been added. All the chapters of the first edition have been revised with pertinent new information, and many have been completely rewritten. Emphasis continues to be placed on the inteφΓetation of biochemical findings in disease of the domestic animal species. A notable exception is the inclusion of information on subhuman primates in the chapter on liver function. We can already anticipate a marked expansion of biochemical knowledge on primates as well as on laboratory animal species that will be included in subsequent editions. Keeping pace with the explosive expansion of new biochemical knowledge among a variety of animal species is a formidable task for the veterinary student, his teachers, the veterinary practitioner, the biomedical researcher, and the experi mental biologist. It is our hope that this volume, primarily devoted to the inter pretation of biochemical findings in diseases of animals, will contribute to the accomplishment of this task. We are deeply indebted to the contributors for their dedicated efforts and per severance. Thanks are also due to the users of the first edition whose many helpful suggestions have guided this revision. Finally, we extend our greatest appreciation to our wives, Frances and Bette, and our families who have cheerfully persevered through this second edition. J.J. Kaneko June, 1970 C. E. Cornelius Preface to the First Edition Interest in the clinical biochemistry of animals has increased rapidly in the past decade owing to the expansion and growth of veterinary science as well as the increas ing use of domestic animals in comparative medical research. Selected data con cerning the changes which occur in the chemical constituents of the blood and tissues can provide for a better understanding of the disease process as well as supply information helpful in differential diagnosis, therapy, and prognostication. This book represents a first attempt to provide the veterinary student, the practitioner of veterinary medicine, and the experimentalist with a specific volume of information concerning the inteφretation of biochemical findings in diseases of domestic animals, and it does not puφort to be a laboratory manual. Methods, however, are included whenever their understanding is believed to greatly enhance the inteφre- tation of the blood chemical findings. The normal values of the various blood con stituents as determined by more recent methods should be of help to all experimental biologists. The information has been gathered from the internationally available scientific literature and, in addition, includes original data obtained in the labora tories of the Department of Clinical Pathology, University of California. Experience in the clinical laboratory has impressed the editors with the difficulty students and practicing veterinarians encounter in bridging the gap between the fundamental sciences and the practice of clinical animal medicine. It is the hope of the editors that this volume will be of help in the application of some of this highly specialized basic knowledge to animal diseases. The topics included in this volume reflect the diagnostic areas of emphasis presently taught in the second semester of a year course in clinical pathology at the School of Veterinary Medicine of the University of California. The editors welcome suggestions for topics to be added in subsequent editions. C. E. Cornelius March, 1963 J.J. Kaneko Contents of Volume II 1. The Kidney: Its Function and Evaluation in Health and Disease George W. Osbaldiston 2. Fluids, Electrolytes, and Acid-Base Balance John B. Tasker 3. Gastrointestinal Function B. C. Tennant and G. O. Ewing 4. Skeletal Muscle George Η. Cardinet, III 5. Hemostasis and Blood Coagulation W. Jean Dodds and J. J. Kaneko 6. Cerebrospinal Fluid Embert H. Coles 7. Synovial Fluid Victor Perman and Charles E. Cornelius 8. Transudates and Exudates Victor Perman 9. Use of Radioactive Isotopes in Veterinary Clinical Biochemistry Jack R. Luick XV Carbohydrate Metabolism J. J. Kaneko I. Introduction 2 II. Digestion 2 III. Absorption 3 IV. Metabolism of Absorbed Carbohydrates 3 A. General 3 B. Storage as Glycogen 3 C. Glycogen Metabolism 5 D. Catabolism of Glucose 10 V. Interrelationships of Carbohydrate, Lipid, and Protein Metabolism 18 A. Lipid Metabolism 19 B. The Influence of Glucose Oxidation on Lipid Metabolism 21 VI. Insulin and Carbohydrate Metabolism 22 A. Insulin 22 B. Mechanism of Insulin Action 23 C. Effects of Insulin 23 VH. Blood Glucose and Its Regulation 24 A. General 24 B. Glucose Supply and Removal 24 C. The Role of the Liver 25 D. Glucose Tolerance 26 VIIL Methodology 27 A. Blood Glucose 27 B. Tolerance Tests 28 IX. Disorders of Carbohydrate Metabolism 33 A. Diabetes Mellitus 33 Β. Hyperinsulinism 38 C. Hypoglycemia of Baby Pigs 39 X. Disorders of Ruminants Associated with Hypoglycemia . . 40 A. General 40 B. Carbohydrate Balance 40 C. Biochemical Alterations in Body Fluids 45 D. Ruminant Ketosis 47 References 49 2 J. J. Kaneko I. INTRODUCTION The sustenance of animal life is dependent on the availability of chemical energy in the form of foodstuffs. The ultimate source of this energy is the sun, and the transformation of solar energy to chemical energy in a form usable by animals is dependent on the chlorophyll-containing plants. The photosynthetic process leading to the reduction of CO2 to carbohydrates may be summarized: ^ ^ chlorophyll ^ 2 2 The principal carbohydrate synthesized by plants and utilized by animals is starch. The large amounts of indigestible cellulose synthesized by plants are utilized by the herbivorous animals, which depend on the cellulolytic action of the microbial flora in their digestive tracts. The biochemical mechanisms by which the chemical energy of foodstuffs are made available to the animal are collectively described as metabolism. Thus, the description of the metabolism of a foodstuff encompasses the biochemical events which occur from the moment of ingestion to its final breakdown and excretion. It is convenient to retain the classical division of metabolism into the three major foodstuffs: carbohydrates, lipids, and proteins. The metabolism of the lipids and proteins are discussed in other chapters. The major function of the ingested carbohydrate is to serve as a source of energy and its storage function is relatively minor. Carbohydrates also function as pre cursors of essential intermediates for use in synthetic processes. When the metabolic machinery of an animal is disrupted, a disease state prevails, e.g., diabetes. The widespread interest and present status of knowledge concerning metabolism and disease is a direct result of the contributions of modern biochemistry. As a corollary, a knowledge of biochemistry is essential. This chapter is not presented as an exhaustive treatise on the subject of carbohydrate biochemistry, but rather as a basis for the better understanding of the disorders associated with carbohydrate metabolism. II. DIGESTION The digestion of carbohydrates in the animal organism begins with the initial contact of these foodstuffs with the enzymes of salivary juice. Starch of plant foods and glycogen of meat are split into their constituent monosaccharides by the action of amylase and maltase. This activity ceases as the food matter passes into the stomach, where the enzymic action is destroyed by the hydrochloric acid. Within the stomach, acid hydrolysis may occur, but the stomach empties too rapidly for complete hydrolysis to take place. Thus, only a small portion of the ingested carbo hydrate is acted upon prior to entrance into the small intestine. Here digestion of carbohydrates takes place quickly by action of the carbohydrate-splitting enzymes contained in the copious quantities of pancreatic juice and in the succus entericus. Starch and glycogen are hydrolyzed to glucose by amylase and maltase; lactose to glucose and galactose by lactase; and sucrose to glucose and fructose by sucrase. 1. Carbohydrate Metabolism 3 These monosaccharide products, glucose, fructose, and galactose, of enzymic hydrolysis of the complex carbohydrates are the principal forms in which absorption occurs. III. ABSORPTION The monosaccharides are almost completely absorbed through the mucosa of the small intestine and appear in the portal circulation as the free sugars. Absorption occurs by two methods: (1) simple diffusion and (2) by an as yet inadequately explained active method. Glucose and galactose are absorbed rapidly and by both methods. Fructose is absorbed at about half the rate of glucose with a portion being converted to glucose in the process. Other monosaccharides, e.g., mannose, are absorbed slowly at a rate consistent with a simple diffusion process. A theory which has remained prevalent to explain the active absorption of glucose across the intestinal mucosa is that the carbohydrates are phosphorylated in the mucosal cell. This process assumes that the phosphorylated sugars are transferred across the mucosal cell and then rehydrolyzed, because free glucose appears in the portal circulation. IV. METABOLISM OF ABSORBED CARBOHYDRATES A. GENERAL The carbohydrate absorbed from the intestine is transported to the liver via the portal circulation. Within the liver, there are several general pathways by which the immediate fate of the absorbed carbohydrate is determined. Fructose and galactose first enter the general metabolic scheme through a series of complex reactions to form glucose phosphates (Fig. 1). The enzyme, galactose-1-P uridyl transferase, which catalyzes the reaction: Galactose-l-P -f UDP-glucose >UDP-galactose + glucose-l-P is blocked or deficient in congenital galactosemia of man (Isselbacher, 1959). The glucose phosphates formed may be converted to and stored as glycogen, catabolized to CO2 and water or, as free glucose, may return to the general circulation. Essentially then, intermediate carbohydrate metabolism of animals evolves about the metabolism of glucose, and the liver becomes the organ of prime importance. B. STORAGE AS GLYCOGEN Glycogen is the chief storage form of carbohydrate in the animal organism and is analogous to the storage of starch by plants. It is found primarily in the liver and in muscle, where it occurs at about 3-6% and about 0.5%, respectively (see Table I). Glycogen is comprised solely of a-o-glucose units linked together through carbon atoms 1 and 4 or 1 and 6. Straight chains of glucose units are formed by the 1-4 links and these are crosslinked by the 1-6 links. The result is a complex ramification
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