CONTENTS 



XXlll 



VIIT. The Metabolism of Cholesterol and Related Sterols in the Animal 

 Body (^continued) 



d. Isovaleric Acid 384 



o. Miscellaneous Compounds 387 



(4) Intermediates in Cholesterol Synthesis. 387 



a. Squalene 387 



b. Cj^clopentenophenanthrene Compoimds 389 



(5) The Source of the Carbons in Biosynthesized Cholesterol 389 



(H) Factors Altering the Biosynthesis of Cholesterol 390 



a. Age 390 



b. Nutritional State 390 



c. Cholesterol Intake 390 



d. The Administration of Cholesterol-Like Compounds 391 



e. The Effect of Fat Feeding 392 



f. The Effect of Soy Sterols 393 



g. The Effect of Cations and of Hydrogen-Ion Concentration . . . 393 



h. The Effect of Hormones 393 



i. The Effect of Vitamin Deficiencies 395 



(a) Pantothenic Acid Deficiency 395 



(b) Biotin Deficiency 396 



(c) Deficiencies in Miscellaneous Vitamins 396 



j. The Effect of Tissue Injury 397 



(7) The Site of Cholesterol Synthesis 397 



(8) The Nature of the Cholesterol-Synthesizing Enzyme 401 



0. The Intermediary Metabolism of Cholesterol 401 



(1 ) Introduction 401 



(2) Experimental Evidence of Cholesterol Destruction in the Tissues. 402 

 a. The Destruction of Cholesterol by Bacteria 402 



(3) Conversion to Cholic Acid and to Other Bile Acids 405 



(4) Conversion to Pregnanediol 407 



(5) Conversion to Adrenocortical Hormones 407 



(6) Conversion to Androgens 409 



(7) Conversion to Estrogens 410 



(8) Conversion to 7-Dehydrocholesterol 410 



(9) Conversion to 7-Keto and 7-Hydroxy Compounds 410 



(10) Hydrogenation of Cholesterol in the Gastrointestinal Tract 411 



(11) Oxidation of Cholesterol, and the Excretion of Oxidation Products 412 



(12) The Excretion of Cholesterol in the Urine 414 



(13) Summary of the Oxidation of Cholesterol in the Animal Body. . . 414 



7. The IntermediarA^ Metabolism of Products Related to Cholesterol ... 415 



(1) Ergosterol 415 



(2) Phytosterols 416 



(3) )3-Cholestanol (Dihydrocholesterol) 417 



(4) Steroid Hormones 418 



8. General Considerations Related to Cholesterol and to the Sterols in 



General 419 



(1) Functions of Cholesterol 419 



a. Relation to Physiologically Important Compoimds 420 



