466 V. BLOOD LIPIDS 



or during fatal mercuric chloride poisoning. Heymann 711 also observed 

 normal or low values for total lipids, cholesterol, and phospholipids in the 

 serum of six patients with mercuric chloride poisoning. The lipid content 

 is also depressed in human beings during the terminal stages of nephritis. 



k. The Blood Lipids in Arteriosclerosis. In the condition of arterioscler- 

 osis, there is a loss in the elasticity of the arteries, associated with a thicken- 

 ing and a hardening of their walls. This condition usually occurs in hyper- 

 tension, although increased blood pressure may originate from a variety of 

 other causes, as well. In the type of arteriosclerosis produced experi- 

 mentally in animals, which is referred to as atherosclerosis, only the intima 

 (the innermost of the three layers of the arterial wall) is involved. The 

 atheromatous lesions (or "patches") present in this layer contain small 

 droplets of lipid material. 



(a) Experimental Studies on Atherosclerosis, a'. The Relationship 

 of Cholesterol to the Formation of the Atheromatous Lesions: The 

 atheromas have been shown, both by microscopical examination and by 

 chemical analysis, to contain considerable proportions of lipids. Cholesterol 

 can readily be detected microscopically in these tissues, because of its 

 characteristic property of birefringence. Morrison and Johnson 715 ob- 

 served that the average cholesterol content of the coronary arteries of pa- 

 tients who had died of acute coronary thrombosis was four times the aver- 

 age for a group of control patients. A number of investigators have demon- 

 strated that cholesterol accumulates in these atheromatous patches by 

 preference. 716 ^ 720 The amount of cholesterol deposited in the aorta of 

 presumably normal persons has been shown by Burger 361 and by Rosen- 

 thal 718 to increase with advancing age. In fact, Bragdon 721 reported that a 

 spontaneous atherosclerosis may be present in aging rabbits. In the later 

 stages of atherosclerosis, calcium is deposited in the atheromas. Because 

 of the predominance of cholesterol in the atheromatous masses, the belief 

 has become widespread that the deposition of cholesterol in the arterial 

 wall is probably attributable to a hypercholesterolemia. 



Bjorksten 722 demonstrated that the intima of fresh hog aortas can be 

 made to adsorb and retain cholesterol from a suspension, provided that 



716 L. M. Morrison and K. D. Johnson, Amer. Heart J., 89, 31-34 (1950). 



716 T. Leary, Arch. Pathol, 82, 507-555 (1941). 



717 C. S. McArthur, Biochem. J., 36, 559-570 (1942). 



718 S. R. Rosenthal, Arch. Pathol, 18, 473-506, 660-698, 827-842 (1934). 



719 R. Schonheimer, Arch. path. Anal Physiol. (Virchow's), 249, 1-42 (1924). 



720 R. Schonheimer, Arch. path. Anal Physiol (Virchow's), 251, 732-738 (1924). 



721 J. H. Bragdon, Circulation, 5, 641-646 (1952). 



722 J. Bjorksten, Proc. Soc. Exptl. Biol Med., 81, 350-353 (1952). 



