Charles A. Slanetz

Nutritional properties of the triglycerides of saturated fatty acids of medium chain-length

SummaryThe influence of a purified rat diet containing 20 or 33% of the saturated medium chain-length triglycerides (MCT) with and without linoleic acid supplements on growth, caloric requirements for weight maintenance and weight increase, fertility, lactation performance, and serum cholesterol levels was compared with that of similar diets containing lard, coconut oil, or no fat.Among male rats maintained on diets containing 20% lard or 20% MCT and .09% linoleic acid for 18 months no differences were observed between the groups other than the depressed body weight and lowered serum cholesterol levels of the group fed MCT. When groups of male rats were kept at constant weight by the daily restricted feeding of diets containing lard, MCT, or coconut oil or no fat plus 2% linoleic acid, the weight-maintenance requirements of the group fed MCT were higher than of those on lard and coconut oil and even somewhat higher than the requirements of the animals fed the fat-free diet. The requirements for weight increase over those for maintenance were 0.9 g. per gram increase for all diets. Additional linoleic acid in the MCT diet decreased the weight and maintenance differences between groups fed MCT and lard.The lactation performance of mothers on MCT plus .09% linoleic acid was poor. The second generation animals initially showed signs of more severe linoleic acid deficiency which however disaappeared without linoleic acid supplements.Some cholesterol levels of animals on MCT were significantly below those of groups on lard. Addition of linoleic acid to the MCT diet did not change the results.

Biological effects of the polymeric residues isolated from autoxidized fats

SummaryThere is increasing evidence that the abnormal nutritional properties of highly autoxidized fats are related to the polymers which develop during autoxidation. Lard and cottonseed oil were aerated at 95°C. for 200 hrs. and molecularly distilled; and the residue fractions, non-volatile at 275 to 300°C., were studied.Diets containing 20% of autoxidatively produced polymeric residue, fed to albino rats, led to diarrhea and rapid death, but when this residue was reduced to 10%, most of the animals were gradually able to tolerate it. At the 4 or 7% level it was well tolerated, but growth was reduced. There were no distinctive histological lesions, and withdrawal of the polymer permitted immediate realimentation without evidence of subsequent injuries.The polymeric residue from autoxidized cottonseed oil exerted a greater growth-depressant effect than that from lard, and the latter, more than that from a hydrogenated vegetable oil used for deep-fat frying for 80 hrs. at 190°C. Addition of fresh fat to the polymeric residues decreased their growth-depressant effect.When rats were fed a measured amount of diet sufficient to maintain their weight, the caloric requirement necessary for weight maintenance gradually decreased. When the dietary fat source consisted of polymeric residue to the extent of 4 to 10%, the caloric requirement for weight maintenance decreased relatively little, if at all. The polymeric residue from autoxidized lard was, in this respect, as effective as that from autoxidized cottonseed oil.

Influence of feeding fractionated esters of autoxidized lard and cottonseed oil on growth, thirst, organ weights, and liver lipids of rats

SummaryLard and cottonseed oil which had been autoxidized at about 100°C. for 210 hrs. were fractionated by a technique involving molecular distillation, conversion to ethyl esters, urea-complex formation, and redistillation. The ethyl esters were then fed to rats for three weeks at a level of 8% in a purified diet. Growth, water intake, organ weights, total liver lipids, and serum and liver cholesterol levels were determined. Groups fed 8% lard served as controls.Growth was severely depressed by the residue fractions of the urea-complex- and noncomplex-forming portions of the original molecular distillates. Of the three fractions from the original molecular distillation residues, the dimeric and polymeric fractions were the most active. The relative liver and kidney weights were usually increased by feeding the growth-depressing fractions. However there were a number of exceptions indicating more specific effects from some of the fractions. Water intakes were lower with the fractions derived from the original molecular distillates than with those from the original molecular distillation residues. Testicular fat body weights suggested that feeding of autoxidized CSO fractions led to less neutral fat deposition than feeding of corresponding autoxidized lard fractions. Dry weight of the enlarged livers was higher, and the total lipid lower than of the control livers. Total liver cholesterol was higher in animals with smaller livers, but there was no difference in the cholesterol content of the total liver lipids. Serum cholesterol levels were lower in animals with large livers.Further study of those fractions having pharmacological properties is suggested.

Nutritional studies of polyglycerol esters

Palatable polyglycerol esters of various mol wt were prepared with fatty acids from cottonseed and peanut oils. The wt gains of weanling male rats fed 1 g/day polyglycerol esters in 5 g of a basic diet were compared with those of matching rats fed 1 g, 0.5 g, and no lard in 5 g basic diet. After three weeks, all rats were given free access to diets containing 8% polyglycerol esters or lard. The polyglycerol esters were utilized as well as lard for wt gain. Intestinal absorption of the fatty acids from the polyglycerol esters was the same as with lard. Autopsies and histological examination of the tissues revealed no abnormalities attributable to the consumption of these materials. Appearance of the animals was normal throughout the experiment. The epididymal fat of the animals was similar regardless of the polyglycerol structure fed. No polyglycerols were detected in the body fat. From these results, it is concluded that the polyglycerol esters of both low and high mol wt were nutritionally similar to naturally occurring fats and that they were nontoxic.

HISTOCHEMISTRY OF UTERINE PIGMENT IN VITAMIN E‐DEFICIENT RATS

The pigment which develops in rats deficient in vitamin E not only serves as an index of the progress of the deficiency but may also provide a clue to the derangement of metabolism which leads to its production. The chemical characterization of the pigment is, consequently, of interest as a definition of an end point in metabolism. It is also necessary as a means of comparison between this pigment and others formed under different circumstances. Many of the salient characteristics of the pigment of vitamin E deficiency have been determined by previous investigators. The methods of histological staining which have been used for its identification have also given information concerning its constitution. Attempts to extract the pigment from adipose tissue by Dam and Granadosl and from uterus and skeletal muscle by Moore and Wang2 have led to contradictory suggestions concerning its composition. The present investigation has been restricted to the application of histochemical methods to tissue sections. Although these methods involve restrictions of temperature, solubility, and brutality of reagent, they have the unassailable advantage of guaranteeing that the observed reaction is due to the pigment itself and not to some artifact of extraction. The investigations reported here were conducted entirely on the pigment present in the smooth muscle and associated macrophages of the uterus of rats on a vitamin E-deficient diet. Although there is reason to believe that this pigment is identical with that which develops in other organs in vitamin E deficiency, the term “uterine pigment” will be employed, since not all of the reactions reported here have been tested on the pigment of other organs. As a matter of convenience in this paper, it will be understood that the hemosiderin in the uterus is not included in the designation “uterine pigment.”

Interrelations of linoleic acid with medium-chain and long-chain saturated triglycerides

Summary1.Effects of medium-chain (C6–C12) saturated triglycerides (MCT) and long-chain (C14–C18) saturated triglycerides (LCT) with and without linoleic acid (LA) supplementation were studied on rats fed purified diets2.With 2% linoleic acid rats fed MCT and LCT grew somewhat better than those on a low-fat diet with the same supplement. Without linoleic acid those fed MCT grew better, and those fed LCT grew worse than those on the corresponding low-fat diet. MCT seemed to decrease, and LCT to increase linoleic acid requirements.3.In survival studies 14 out of 18 rats fed 20% MCT were alive after 2 years; of their controls fed 20% lard, 10 out of 19 survived.4.Reproduction studies in females gave equally poor results on unsupplemented low-fat, MCT, and LCT diets regarding implantation, birth weight, and survival rate. The weaning weights of the young on MCT were however the highest. With 2% LA weaning weights were equally high with LCT and MCT but lower with low-fat diet.5.In animals fed low-fat diets not supplemented with LA, low serum cholesterol was associated with high liver cholesterol. With MCT, serum values were higher and liver values were significantly lower. With unsupplemented LCT, serum and liver values were high. When the three diets were supplemented with 2% LA, there were no longer any differences in the serum levels and in the liver levels. Whether ar not the presence of some oleate in the MCT and LCT influenced the cholesterol results is not certain.6.The differences in the effects of MCT and LCT are discussed.

Relation of Vitamin A and “Lard Factor” to Disease Caused by Rancid Lard.

Summary 1. The fatal disease occurring in rats maintained on a purified, vit. A-free diet containing 10% rancid lard (peroxide No. 256) could be prevented by extra feeding of massive doses of synthetic vit. A palmitate or crystalline beta-carotene or cod liver oil. 2. Addition of the distillate fraction of molecularly distilled lard to the diet largely prevented the disease, although this fraction contains only traces of the known forms of vit. A. This “lard factor”, when added to the diet, was more resistant to the action of rancid lard than beta-carotene and vit. A palmitate. 3. Aversion to the diet or improper intestinal fat absorption were not responsible for the results. 4. It was concluded that rancid fats are not toxic per se and that, under natural conditions, the “lard factor” may play an important part in the prevention of the disease ascribed to vit. A deficiency.

EFFECTS OF OVARIAN HORMONES UPON UTERINE PIGMENTATION IN VITAMIN E-DEFICIENT RATS

Acid-fast pigmentation of the skeletal and cardiac musculature and the smooth muscle of the reproductive tract is now recognized as being characteristic of vitamin E deficiency in the rat. The chocolate-brown discoloration of the uterus was first noted in the E-deficient rat by Martin and Moore.’ Subsequent histological studies demonstrated that pigment was deposited in fine granules in the cells of the uterine musculature?, Mason and Emmel“ further noted the presence of numerous pigment-laden macrophages scattered throughout the uterus of the E-deficient rat. Their findings indicated that the pigment was deposited first in the muscle cells and later transferred to the macrophages. The rale of the gonads in the regulation of the functional activity of the musculature of the reproductive tract, particularly that of the uterus, has suggested the possibility of a physiological relationship between the gonadal hormones and vitamin E. Mason and EmmeP did not observe any diminution in muscle pigmentation in prepuberally ovariectomized animals as compared with intact controls. Ovariectomy, however, was followed by a decrease in the number of pigment-containing macrophages appearing during the course of the avitaminosis. More re~ent ly ,~ it has been shown that a definite decrease in muscle pigment occurs when ovariectomized rats are maintained on it diet containing a lower percentage of fat than the ration used by Mason and Emmel. The present experiments were undertaken to ascertain the effect of ovarian hormone treatment upon the deposition of uterine pigment in ovariectomized E-deficient rats maintained on a relatively low unsaturated fat intake.

Influence of Alpha Tocopherol on Implantation in Old Rats.

Summary 1. The implantation rate in female rats on a purified diet containing about .1-.4 mg of tocopherols per 100 g diet was compared with the implantation rates in animals on the same diet receiving single and continuous supplements of synthetic dl alpha tocopherol acetate. 2. Failure of implantation was observed after the eighth month in females without tocopherol supplements. With continuous tocopherol administration, the implantation rate was normal after one year. Single post-mating tocopherol supplements increased the implantation rate in older rats significantly. The requirements necessary for successful implantation in older rats vary widely and increase steeply with age. 3. Infections of the uterus and the tubes were frequently observed in the deficient rats, but not in those on the complete diet. Presence of infection does not explain the higher implantation rate after single post-mating tocopherol doses. 4. The changes leading to the failure of implantation are prevented, but once present, only partly counteracted by alpha tocopherol acetate.

The Effect of Phosphatides on Utilization of Vitamin A and Carotene

Summary Vitamin A-depleted rats fed a vitamin-free diet, supplemented with synthetic B vitamins and 2 U.S.P. units of vitamin A in the form of carotene, failed to gain weight in spite of the presence of 4% cottonseed oil in the diet. Satisfactory growth was obtained when soybean phosphatides (1%) were added to the diet. An amount of soybean oil (0.3 %) equivalent to that contained in the soybean phosphatides used also promoted growth but to a lesser degree. Rats fed the vitamin A-deficient diet supplemented with soybean oil and 2 units of vitamin A appeared in poor condition and began to lose weight after the third week. Substitution of cod liver oil in place of carotene as the source of vitamin A in the diet, with addition of soybean oil or soybean phosphatides resulted in a growth response similar to that obtained with carotene. However, cod liver oil alone also caused some gain in weight. In the presence of soybean phosphatides, carotene was as well utilized as vitamin A under the conditions of our experiment.