Further investigations on the, reduction of vitamin A content in the liver of rats fed a 0.1% PCB diet were conducted. The first experiment, in which rats were fed a 0.1% PCB diet for 8 weeks and vitamin A in the liver was determined at 2-week intervals, suggested that a significant decrease of vitamin A in the liver might occur within 2 weeks of PCB ingestion. In the second experiment a significant reduction of vitamin A content per gram of liver, but not per whole liver, in rats fed a 0.1% PCB diet was observed on the 3rd day of PCB ingestion, and then on the 6th day the difference between the control group and the PCB-fed group became much more remarkable. But thereafter no further reduc tion was seen, indicating a lower limit of vitamin A concentration in the liver of rats fed PCB. It was found that retinol binding protein in the serum of rats fed the 0.1% PCB diet decreased to one-half that of the control group on the 10th day of PCB ingestion, suggesting also a marked reduction in serum vitamin A level. Another experiment revealed that a decrease in hepatic vitamin A oc curred even at low PCB levels, but serum phospholipid did not respond at all to any PCB level examined until 7 days after PCB ingestion began. The mechanisms of sensitive response of vitamin A in the animals fed PCB are briefly discussed.
Derivatives of ascorbic acid were synthesized, and the studies were made on their effects in Ehrlich ascites carcinoma cells, in regard to the inhibition and the prolongation of survival time as well as on the morphological degeneration in HeLa cells. In a model infection study carried out by using tetraacetyl-bis-dehydroascorbic acid in dd mice infected with Ehrlich cells, it was proved that the prolongation of survival time was nearly double in comparison to the control group mice. Also, it was noted that hypertrophy due to abdominal dropsy and body weight were reduced much more than in the control group. From these results, the inhibiting effect of tetraacetyl-bis-dehydroascorbic acid was confirmed. While in the case of DHA and other derivatives, almost no inhibition and prolongation of survival time were observed. As for HeLa cells in a tissue culture, tetraacetyl-bis-DHA, in a dosage of 125-250 μg/ml, demonstrated definitely its morphological degenera tion. After 125 μg/ml of tetraacetyl-bis-DHA was added to a tissue culture solution of HeLa cells, the cells were washed and recultured. No growth of the cells was observed. Consequently, this substance was confirmed to be anti-HeLa substance with a low toxicity.
Before industrial production of thiamine became possible, among many beriberi patients some showed symptoms of encephalopathy, the cerebral form of the disease. In this animal experiment, thiamine deficient rats showed failure or blocking of the operant behavior in the maze box, pole climbing box and shuttle box, indicating orientation disturbance and defective memory. This Wernicke's syndrome-like sign dramatically disappeared by treatment with thiamine. Potentiated narcosis with thiopental or alcohol induced in thiamine-deficient rats and mice was readily reversible by thiamine administration. These pheno mena are associated with thiamine content of the brain and are found long before histopathological changes in the brain of deficient animals. It is easily surmised that thiamine deficiency in the brain may block the brain metabolism and subsequently cause changes in any chemical sub stances in the brain, refracting on biophysical phenomenon, such as EEG. However, in the present study, generally speaking, no meaningful results concerning these points were obtained.
Duodenal brush border membrane proteins were studied in chicks at different developmental stages. The protein pattern obtained from polyacrylamide gels with 2-day-old chick preparations was dis tinctly different from that obtained with 20-day embryos. The most remarkable changes were seen in the region of a protein with an Rf of 0.25, an area with high sucrase and maltase activity, and in the region of a protein with an Rf of 0.28, which was characterized by alkaline phosphatase activity. These proteins reacted strongly with carbohy drate stain after hatching.
The present study attempts to improve the proteins from a blue-green alga Spirulina maxima and a non-sulfur purple bacterium Rhodopseudomonas capsulatus through their peptic hydrolysis followed by plastein synthesis with papain. The former enzymatic process was effective in removing some photosynthetic pigments and flavors orig inating in the raw materials. The latter process. was successful in incorporating limited amounts of methionine, lysine, and tryptophan, and thus to synthesize plasteins whose essential amino acid patterns re semble the FAO/WHO suggested pattern (1973). These plasteins had no colors and no flavors.
The effect of osmotic pressure of diets on the food intake of young rats was investigated by comparing the nutritional effect of casein with the corresponding amino acid mixture at 3.2% nitrogen level. Changes in the osmolarity of diets due to the type of dietary carbohydrate had a little effect on food intake, whereas partial substitution of casein for amino acids resulted in significant increase in foodd intake. Weight gain and food intake of rats fed the 25% replaced amino acid diet were compared with those of rats fed the casein diet. Food intake was lower at 12.5% replacement than at 25% replacement. These observations suggest that a well-balanced amino acid mixture supported maximal growth of rats when 25% of the amino acid mixture was replaced with casein. This suggestion could be experimentally confirmed by using an amino acid mixture based on the amino acid composition of whole-egg protein.
The growth retardation and external pathological lesions that occur in rats fed a 10% casein diet containing 5% tyrosine could be alleviated by the supplementation of extra protein (20% casein) or 0.66% methionine plus 0.90% threonine (equivalent to the contents in a 20% casein, . respectively). Liver tyrosine aminotransferase activity is elevated by ingestion of excess tyrosine, but lowered by the supplementa tion of extra casein or methionine plus threonine. In rats fed a high tyrosine diet supplemented with methionine plus threonine, liver p-hydroxyphenylpyruvate hydroxylase activity was not higher than that of the 10% casein group, but liver homogentisate oxidase activity in creased significantly. When excess tyrosine was included in the 10 casein diet, free tyrosine concentrations in plasma, liver, muscle and brain were extremely elevated, but when the high tyrosine diet was sup plemented with extra casein or methionine: plus threonine, theirr plasma and tissues tyrosine concentrations lowered significantly. A large in, crease in total phenols, p-hydroxyphenylpyruvate and free tyrosine excretions in urine was produced in animals fed the high tyrosine-low protein diet, but these were lowered by the supplementation of methio nine and threonine to the diet.