414 VIII. CHOLESTEROL AND RELATED STEROLS 



cally-active acid with a probable empirical formula of C07H46O4 is present 

 in this fraction. Therefore, the possibility exists that the increased acids 

 are partly to be ascribed to the bile acids. Cook and Thomson^^^ reported 

 that rabbits and guinea pigs destroyed a larger proportion of cholesterol 

 than did rats; the comparative figures based upon unsaponifiable matter 

 were 24% as contrasted with 18%. When the data for cholesterol metabo- 

 lism were based upon the amount of sterol metabolized, the value for rab- 

 bits and guinea pigs was 54% as contrasted with a figure of 44% for rats. 

 When 10 g. of cholesterol was administered to man in 50 g. of olive oil, 

 about 20% of the cholesterol was absorbed, and an increased excretion of 

 fecal acids was noted; however, no marked effect upon plasma cholesterol 

 could be observed. ^^^ 



(12) The Excretion of Cholesterol in the Urine 



Cholesterol is not normally a component of urine. As discussed in Sec- 

 tion (10), most of the excreted cholesterol is eliminated via the walls of the 

 intestine in the feces. After oxidation of cholesterol in the liver, much of 

 the water-soluble product is excreted into the intestine by way of the bile. 



Burchell and Maclagan'^^ showed that an association exists between the 

 supernatant urine cholesterol and a proteose fraction. Much or all of the 

 urinary cholesterol was found in the urinary deposit or associated with 

 heat-coagulable protein when present. It was reported by Burchell 

 et al.,^^^ that the cholesterol in urine deposits from cancerous subjects varied 

 from to 0.05 mg. per twelve hr. in men and from to 0.42 mg. per twelve 

 hr. in women. The supernatant urine cholesterol varied between and 

 0.5 mg. per twelve hr., with no sex difference. The supernatant urine 

 cholesterol was increased in albuminuria, while hematuria and pyuria in- 

 creased the urine-deposited cholesterol. Kayser and Balot^^^ stated that 

 these forms of urinary cholesterol have their origin mostly in the mucus 

 formed in the urogenital tract. In albuminuria the urinary cholesterol is 

 derived from the plasma; it is present in the form of lipoprotein. 



(13) Summary of the Oxidation of Cholesterol 



in the Animal Body 



Under ordinary conditions, cholesterol (and presumably other sterols) 

 are oxidized to only a minor degree. In most cases, the cyclopenteno- 



3« R. p. Cook and R. O. Thomson, Biochem. J., 49, 72-77 (1951). 



»66 R. p. Cook and D. C. Edwards, Biochem. J., 49, xli (1951). 



3" M. Burchell and N. F. Maclagan, Biochem. J., 44, iv (1949). 



358 M. Burchell, J. H. O. Earle, and N. F. Maclagan, Biochem. J., 44, iv (1949). 



369 F. Kayser and R. Balot, Bull. soc. chim. biol, 34, 806-812 (1952). 



