FATS AS ESSENTIAL DIETARY COMPONENTS 875 



ate the toxicity of this chemical. In the case of rats suffering hypothalamic 

 injury, Lundbaek and Stevenson"" obser\'ed that the weight gains were 

 greater on the high-fat, non-carbohydrate diet than on high-carbohydrate 

 diets. 



Although normal growth was obser\'ed when a low-fat diet (0.5% 

 corn oil) was fed to growing mice, a retardation of growth w'as noted when 

 metabolic stresses such as certain intestinal bacteriostatic agents were 

 added to the diet. The substances which produced this retardation in 

 grow^th included succdnylsulfathiazole, streptomycin and atabrine, as 

 well as thyroid and triacetin.^^^ The retardation in growth could be pre- 

 vented if fatty acids or partially defatted cottonseed meal or water- 

 extracted liver residue were included in the diet. The deleterious effect 

 of the bacteriostatic agents is believed to be due to the fact that they inter- 

 fere with the synthesis of long-chain fatty acids by the organism. It 

 was suggested that cottonseed meal and liver contain a factor essential 

 for the synthesis of fat by the animal. 



A relationship has also been shown to exist between the duration of 

 thiopental anesthesia and the amount of fat available. Thus, according 

 to Hermann and Wood^" a 5 g.% decrease in the body fat of a rat resulted 

 in a 100% increase in the duration of thiopental anesthesia at a fixed thio- 

 pental dosage, or a 40% decrease in the thiopental required for a given 

 period of anesthesia. In contrast to this, the anesthetic effect of penta- 

 barbitol was not affected by the amount of body fat. It w^as also demon- 

 strated by Anderson and Magee^"^ that the ingestion of oil by rats prelimi- 

 nary to thiopental anesthesia decreased the period of anesthesia by about 

 50%. It is believed that this is to be explained by the production of 

 hyperlipemia by the oil, with the resultant uptake of the circulating thio- 

 pental by the chylomicrons. 



{9) The Effect of Dietary Fat upon Galactose Absorption 



Schantz, Elvehjem, and Hart^^^ first called attention to the fact that 

 galactose appeared in the urine of rats and of other animals which were fed 

 on a mineralized skim-milk diet. On the other hand, it was shown that 

 the excretion of galactose did not occur when a diet consisting of whole 

 milk w^as employed. Like^^^se, when 3 or 4% of fat (butter, lard, corn 

 oil, coconut oil, linseed oil, palmitic and oleic acids) was added to skim 



i6« D. K. Bosshardt and J. W. Huff, /. Nutrition, 50, 117-127 (1953). 



1" G. Hermann and H. A. Wood, Proc. Soc. Exptl. Biol. Med., 80, 318-319 (1952). 



158 E. G. Anderson and D. F. Magee, Proc. Soc. Exptl. Biol. Med., 83, llO-lll (1953). 



"» E. J. Schantz, C. A. Elvehjem, and E. B. Hart, /. Biol. Chan., 122, 381-390 (1938). 



