FACTORS ALTERING CONCENTRATION OF BLOOD LIPIDS 



477 



fractions designated as S f 17-20, S f 20-40, and S f 40-40,000. The S f 

 40,000 class appears to consist of the chylomicrons. 



Gofman 768 described the chemical nature of the several flotation areas, 

 from unpublished work of Lindgren, Freeman, and Nichols. All S f samples 

 contain some cholesterol. The total content of cholesterol decreases 

 steadily from 30% in the S f 4-6 fraction to 5% in the S f 40-40,000 molecule 

 class, while the proportion of esterified cholesterol changes from 75 to 



260 - 



180 - 



20 40 



S, 12-20 



60 80 100 120 



LIPOPROTEINS, MO. % 



140 



Fig. 8. The average S f 12-20 lipoproteins plotted against the S f 20- 

 100 lipoproteins in serum of normal individuals and of patients with 

 coronary disease. 768 



0% within these limits. Phospholipid and protein both decrease gradu- 

 ally from 25% levels in the S f 4-6 fraction to approximately 5% in 

 the largest molecules. On the other hand, glyceryl esters are absent, or 

 are present only in very low percentages in the S f 4-6 fraction ; however, 

 they increase steadily until they comprise 75 to 85% in the S f 40-40,000 

 fraction within which the chylomicrons fall. 



The comparative amounts of S f 12-20 and S f 20-100 lipoproteins in a 

 group of normal persons and of some coronary patients are given in Figure 8. 



The seriousness of atherosclerosis is believed to be related to the total 



