Measures Affecting the Diseases in Animals

Many observations in animals have been discussed already in Section II and therefore only a brief survey will be given here. 

Atherosclerosis can occur spontaneously in various animals for instance, in old hens (Weitzel, 1956) and in the parrot (Cohrs, 1957), and probably in other animals (fed by man ) too. The atheroma, easily induced by high-cholesterol diets in rabbits and chickens cannot be considered comparable to the spontaneous disease in man. Such experiments as that carried out by Fillios et al. (1956), who supplemented purified diets with cholesterol, sodium cholate, and thiouracil, should be left out of consideration because a low basal metabolic rate was induced. However, the rats developed a blood pattern like that present in the human patient, together with coronary and aortic lesions, and lesions in the heart valves. Because no similar data for toxemia in pregnancy have yet been found, only the results in mammals with a normal metabolic rate will be considered. Similarly, animal experiments in which cholate, cholic acid, or other surface-active agents are used cannot be considered here. 

Wissler et al. (1954) and Moskowitz et al. (1956) produced atheromatous lesions in middle-aged obese male rats with a diet with an average composition similar to actual diets of certain patients. This diet was not choline deficient, but contained lard to an appreciable amount however, the choline seemed to have an aggravating effect on the lesions. The difference in results in this and the foregoing experiments cannot yet be explained. It certainly points to the important role of imbalance in the dietary composition, and the possible odd effects of relative deficiencies. A similar observation was made by Jones et al. (1957) with methionine, which gave a hypercholesterolemia but was without effect on the number of lesions. Methionine given together with vitamin E, however, reduced the cholesterol levels to those of the normal controls, while vitamin E alone did not have this effect. 

The cod liver oil proved to be the critical component of the diet. Substitution by com oil made the diet nontoxic, and crude linoleic acid was approximately as effective. The eclamptic disease could be prevented by treating the animals with a-tocopherol or lettuce before the toxic diet was given, or by adding these materials to the eclamptogenic diet. Apart from a possible toxic effect of the vitamin D, it is also possible that the oil itself has a toxic effect. It is known that highly unsaturated acids are present which do not have the activity of the essential unsaturated fatty acids, because they have cis-trans and trans-trans configurations instead of the active cis-ds form. Even deficiency of the essential unsaturated fatty acids may be promoted. The crude linoleic acid, which was not quite as active as corn oil, may contain about 50% of the inactive cis-trans configura-tion(s). The vitamin E content of the com oil is probably important also. 

An effect of niacin in decreasing the blood cholesterol level was observed by Altschul (1956), Altschul et al. (1955), and Altschul and Hoffer (1958), in rabbits. Schon (1958) found a similar result in the liver cholesterol levels of the rat. 

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