The bile acids as principal end products of cholesterol metabolism occupy a focal position in our understanding of the role of steroids in bio logical systems. The biogenesis of bile acids from cholesterol in higher ani mals, and their functions in regulating sterol metabolism and in gastrointestinal physiology have been elucidated by the development of elegant methodo logical approaches during the last two decades. The molecular pleomorphism exhibited by the bile acids and bile alcohols in the animal kingdom is a classic example of their role in biochemical evolution. The total story of the bile acids, their chemistry, their role in normal and abnormal physiological processes, and their significance in biochemical evolution has never been available in the form of a comprehensive treatise written in the words of those who have contributed to the development of our knowledge in this area. The Bile Acids, in two volumes, will serve to fill this void, and will also bring together information which will prove in valuable to both the biochemist and the medical scientist. We wish to thank Mrs. Sally Wiseman and Mrs. Lillian Haas for their invaluable assistance with the editing of the manuscripts. This work was supported in part by grants AM-02131, General Research Support SS0-1- FR-05479 (P.P.N.), HE-03299, HE-05209, and a National Heart Institute Research Career Award (D.K. ), K6-HE-734, from the National Institutes of Health, United States Public Health Service. P.P.N. Baltimore, Maryland D.K."

The first two volumes of this series addressed themselves to the chemistry, physiology, and metabolism of the bile acids. The present volume is devoted to the pathophysiology of bile acids. As the role of bile acids in health and disease is being increasingly recognized, we have chosen for discussion a wide range of topics of current importance. The presence of bile acids in brain tissue and their possible role in demyelinating diseases form the subject of a provocative discussion. As an extension of this theme, the presence and quantification of bile acids in extrahepatic tissues is the subject of one chapter. The pathophysiological implications of bile acids at the macromolecular level is highlighted by a chapter on the influence of bile salts on the activity of various enzymes. The general area of hepatobiliary diseases is discussed in two chapters: one describes changes in bile salt metabolism in liver diseases and the other focuses on cholesterol gallstones and their formation and dissolution. Cerebrotendinous xanthomatosis has been shown to entail a defect in bile acid and sterol metabolism, and this metabolic error is the subject of an illuminating exposition. There is presently a concerted research effort being brought to bear on the causes of colon cancer, and one important aspect of this work centers on bile acid metabolism. Aspects of bile acid metabolism and cancer are the subject of two chapters. And finally, the role of dietary fiber in bile acid metabolism is updated.

Over a decade has elapsed since the last volume in this series was published. At that time we considered that we had comprehensively covered all aspects relating to bile acid chemistry and physiology. However, major strides have been made in our understanding of the physiology and pathophysiology of bile acids, due largely to the great advances which have taken place in analytical technology. As a result, the need to document these advances was felt acutely, and therefore this volume is devoted to methodologies in bile acid analysis and their applications. This volume includes twelve chapters written by prominent scientists in the field of bile acid research. The initial chapter discusses techniques of extraction and isolation of bile acids from biological fluids. It is followed by descriptions of physical methods of analysis and discussions of the way these techniques have been applied in the field of bile acid research. Of practical value is the inclusion of a comprehensive list of spectra obtained for refer ences by nuclear magnetic resonance spectroscopy and mass spectrometry . These chapters are followed by reviews of biological methods of immuno assay and bioluminescence. Specific applications of these techniques are then addressed in contributions relating to bile acid analysis of tissue, serum, urine, and feces. With this integrated approach we have attempted to provide a volume which represents a comprehensive review of the analytical field of bile acids, while also serving as a useful reference book for those workers involved in bile acid analysis."