462 V. BLOOD LIPIDS 



Irrespective of whether the serum cholesterol is high or low, an elevation 

 in the ratio of free cholesterol : total cholesterol is the rule. In cases in 

 which the total cholesterol has reached abnormally low levels, the propor- 

 tion of esterified cholesterol may approach zero. One of the widely ac- 

 cepted criteria of liver function over a number of years has been the ability 

 of this organ to form cholesterol esters. The lowering of the combined 

 fraction of this sterol in severe hepatitis is therefore an expression of 

 the weakening of that function. On the other hand, Turner et a/. 674 re- 

 ported a low activity on the part of the cholesterol-esterifying enzyme in 

 human serum in hepatitis. These workers state that the decreasing en- 

 zyme activity is an ominous prognostic sign. 



(d) In Cirrhosis of the Liver. No consistent results have been reported 

 in regard to the pattern of serum lipids in this condition. In the terminal 

 stages coincident with a decreased amount of functioning liver tissue, 

 serum cholesterol reaches subnormal levels, 215 ' 633 ' 672 lipid phosphorus is re- 

 duced, but the lipid phosphorus : cholesterol ratio remains practically 

 .unchanged. Man et a/. 215 reported relatively low values for neutral fat in 

 the serum under these conditions. A larger proportion of the cholesterol 

 is also free. 215,256 This is in line with the report of Turner et a/., 674 who 

 observed a lower concentration of the cholesterol-esterifying enzyme in the 

 serum of such patients. 



(e) Following Partial or Functional Hepatectomy. Friedman and as- 

 sociates 689 reported that when the plasma cholesterol levels of rats were 

 drastically reduced by plasmapheresis, the restoration of this sterol was 

 inhibited or prevented for twenty-four hours following partial hepatectomy. 

 These workers concluded that the liver is responsible for the maintenance of 

 the normal plasma cholesterol content. However, Chanutin and 

 Gjessing 690 did not report a decrease in cholesterol, total lipid or cholesterol 

 in rats after partial hepatectomy, laparotomy, thermal injury, or after the 

 injection of tris(/3-chloroethyl) amine. However, plasmapheresis was not 

 employed, and the degree of functional activity of the liver may have 

 varied from that in the experiments of Friedman et a/. 689 



Ranney and ChaikofT 691 observed that the hyperlipemia which is 

 ordinarily observed in birds following the injection of diethylstilbestrol 

 does not occur in fowl subjected to functional hepatectomy. This indi- 

 cates that the augmentation of the blood lipids following this estrogenic 

 agent is dependent upon the presence of the liver. 



689 M. Friedman, S. O. Byers, and F. Michaelis, Am. J. Physiol, 164, 789-791 (1951). 



690 A. Chanutin and E. C. Gjessing, J. Biol. Chem., 178, 1-5 (1949). 



6' 1 R, E. Ranney and I. L. Chaikoff, Am. J. Physiol, 165, 600-603 (1951). 



