RATS fed on low protein diets of high fat content with or without small amounts of cholesterol develop intensely fatty livers; when caseinogen is used as the dietary protein, the degree of fat infiltration diminishes on increasing the amount of this protein present in the diet, irrespective of any action of choline [Channon & Wilkinson, 1935; Beeston et al. 1935]. Further work has shown that a daily intake of 1 g. caseinogen has an effect equivalent to that of 7-8 mg. choline [Beeston & Channon, 1935; Beeston et al. 1936]. Best et al. [1936] obtained similar results regarding this extensive action of caseinogen on liver fat deposition in preventive experiments. While we are continuing our studies of the action of pure amino-acids as one method of elucidating the mechanism of this action of caseinogen [Beeston & Channon, 1936; Channon et al. 1938], information as to the relative lipotropic actions of other proteins is desirable for two reasons. Firstly, it would enable the intensity of action of different proteins to be studied in relation to their amino-acid composition, and perhaps provide evidence of value from this point of view; secondly, it is important to determine which proteins are most satisfactory from the experimental point of view. Diets low in protein tend to cause weight losses even in the short term studies often used in this type of work, and a balance has to be struck between the desirable high fat percentage in the liver and ensuing weight losses. The work described in this paper is, therefore, a study of the actions of a number of plant and animal proteins in preventing fat deposition in the liver, caseinogen being used as the standard. EXPERIMENTAL Preparation of the proteins Edestin was crystallized from 5 % NaCl extracts of hempseed, washed twice with water, twice with alcohol and with ether; the dried powder was extracted twice with hot alcobol and with ether. Yield 75-80 g./kg. hempseed. Fibrin obtained from the slaughterhouse was water-washed until colourless, and dried in alcohol; the powdered product was extracted with water, cold alcohol, hot alcohol and finally with ether. Gliadin. Repeated extraction with 73 % alcohol (3, 3 and 2 1.) of wheat gluten flour (1 kg.), concentration in vacuo of the extracts and cooling in the refrigerator gave a jelly of gliadin, which was dehydrated by successive treatments with acetone; the finely ground product was extracted with cold absolute alcohol and with ether. Yield 275-290 g./kg. gluten flour. Zein. Maize gluten meal (1 kg.) was extracted repeatedly with hot 80 % alcohol (4, 2 and 2 1.), the extract concentrated to 2-5 1., and mixed with 2-5 1. of ether. The gelatinous precipitate was dissolved in warm 90 % alcohol and (976)
Hershey & Soskin [1931] reported that fat infiltration into the liver of depancreatized dogs was accelerated when a relatively saturated fat, such as beef suet, was added to a diet of lean meat and sucrose; in contrast, the addition of the highly unsaturated fat codliver oil had no such effect, for a dog receiving it showed no symptoms of liver dysfunction and' at post-mortem examination the fat content of its liver was found to be normal.Further study of the effect' of the nature of food fat on the amount of fat deposited in the liver was made by Channon & Wilkinson [1936] in experiments on dietary fatty liver production in rats. In this works six different fats-butter fat, beef dripping, palm oil, coconut oil, olive oil and cod-liver oil-chosen because of the wide differences in their chemical composition, were used. The results showed that with the single exception of coconut oil (i.v. 10) the amounts of fat deposited in the'liver varied inversely with the iodine value, butter (i.v. 33) causing.6 times the degree of fat infiltration which resulted from cod-liver oil (i.v. 145). When the results were considered in relation to the saturated 'acid content of the fats, it seemed that without exception the fat deposition depended
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