B. C. Johnson

Effect of Feeding Different Amino Acid Diets on Growth Rate and Nitrogen Retention of Weanling Rats.

Summary True body growth of over 6 g day approaching that obtained with an Intact protein diet was obtained by feeding weanling rats a pure amino acid diet equivalent to 10% protein. This rapid rate of growth was obtained by increasing the arginine content of the diet over that previously used. 0.5% arginine HCl appeared to be the requirement level for optimum growth.SummaryTrue body growth of over 6 g day approaching that obtained with an Intact protein diet was obtained by feeding weanling rats a pure amino acid diet equivalent to 10% protein. This rapid rate of growth was obtained by increasing the arginine content of the diet over that previously used. 0.5% arginine HCl appeared to be the requirement level for optimum growth.

Production of dietary vit. K deficiency in the rat.

SummaryA diet is described which produces a severe Vit. K deficiency in the rat in less than 10 days. The deficiency was manifested by prolonged plasma prothrombin times and hemorrhages. Daily menadione supplementation protected rats from the deficiency. Coprophagy appeared to be the means by which Vit. K synthesized by the intestinal microflora becomes available to the rat.Summary A diet is described which produces a severe Vit. K deficiency in the rat in less than 10 days. The deficiency was manifested by prolonged plasma prothrombin times and hemorrhages. Daily menadione supplementation protected rats from the deficiency. Coprophagy appeared to be the means by which Vit. K synthesized by the intestinal microflora becomes available to the rat.

Glucose metabolism in the rat during starvation and refeeding following starvation.

Summary Metabolism of glucose in starved and starved-refed rats was markedly different from pathways observed in non-starved, normal rats. “Supernormal lipogenesis” was observed in liver, heart and kidneys of starved rats, and the lipogenesis was increased some 90-fold in livers of starved-refed rats. The proportion of C14 in “neutral fat” to total fat was increased 2- to 3-fold in hearts and kidneys of starved-refed rats, although the total lipid contents in these organs were not appreciably affected. Neither glucose oxidation nor incorporation of C14 from glucose into lipids by homogenates of rat hearts was affected by prior starvation and refeeding.

Effect of Aureomycin on Utilization of Vitamin A in the Growing Male Albino Rat

Summary 1. Growing male albino rats were fed vit. A ester at levels of 0, 0.75, and 7.5 γ/rat/day. Comparisons were made at these levels of vit. A intake with and without aureomycin added to the diet at the rate of 100 mg/kg. 2. Statistically significant differences were found in weight gains and food intakes between groups receiving different levels of vit. A. 3. Statistically significant differences were not found in weight gains and food intakes between groups receiving antibiotic and their controls at the various levels of intake of vit. A, except on vit. A-free diets. Here weight gains and food intake of the control animals were significantly greater than for animals receiving antibiotics. 4. At a level of intake of vit. A of 7.5 γ/day no significant difference of liver storage was found upon aureomycin supplementation. Kidney storage of aureomycin supplemented animals was significantly less than that of control animals. Under conditions of this experiment at the 7.5 γ /day level of supplementation of vit. A significantly greater storage of vit. A occurred in the liver than in the kidneys. 5. No effect of sparing of vit. A by aureomycin was demonstrated, but on vit. A-free diets aureomycin appeared to enhance the deficiency syndrome.

Effect of Antibacterial Agents on Growth of Baby Pigs Fed a “Synthetic” Diet

Summary Aureomycin stimulated the growth of baby pigs on an alpha protein “synthetic milk” diet. It did not reduce the coliform lactobacilli or yeast cells present in the feces. Sulfathalidine reduced the number of coliform bacteria present in the feces. There was no statistically significant beneficial growth-promoting effect from adding penicillin or sulfathalidine to the diet.

Some Effects of Methyl Linoleate Hydroperoxide on Oxidative Phosphorylation in Rat Liver Mitochondria.

The effects of methyl linoleate hydroperoxide (MLHP), a peroxidation product of methyl linoleate, on the denaturation of the lipoproteins (Nishida and Kummerow(9)) and on certain pathologic disorders in animals simulating vitamin E deficiency is well known. Both the denaturation phenomenon and the pathologic disorders are alleviated by αtocopherol supplementation (Nishida and Kummerow(10)). Evidence is reported here which indicates that MLHP has an inhibiting effect on the coupling of phosphorylation with oxidation in rat liver mitochondria. Materials and methods. Mitochondria were prepared from the livers of normal adult Sprague-Dawley male rats on a stock laboratory diet by the Hogeboom-method (Hoge-boom(4)), using 0.25 M sucrose. The conventional Warburg procedure was used to measure oxygen uptake over a 30-minute period at 30° following a 6-minute preincubation (see footnote to Table I for composition of media). Incubation time was terminated by addition of 5% trichloroacetic acid (TCA). The inorganic phosphate remaining in each vessel was determined by Lowrys method(6). The P/O ratio was calculated from the values observed. The protein content of each tissue sample was determined by the use of phenol reagent (Lowry and Lopez(7)). The extent of peroxidation in mitochondria was determined by the barbituric acid (TBA) reaction method of Corwin(1), with the exception that 0.5 ml of the mitochondrial preparation was used in place of whole liver homogenate. To prepare MLHP, 50 g of methyl linoleate urea complex (Hormel Institute, Univ. of Minnesota) was extracted with 100 ml of hot 1 N HC1, and the methyl linoleate was washed 3-4 times, each time with 100 ml of water. The pure methyl linoleate was extracted with 30 ml of Skelly Solve F (SSF). After evaporation of the SSF under nitrogen (yield 13 g), 1 g of the oily methyl linoleate residue was incubated overnight at 0°C in 100 ml of 0.2 M phosphate buffer, pH 8, containing 20 mg lipoxidase (10,000 μ/mg, Sigma) with constant stirring.

Response of pigs to streptomycin.

Summary The addition of 500 mg per kg dry matter of streptomycin to a nutritionally adequate “synthetic milk” containing 2 g of sulfathalidine per liter produced a highly significant increase in the average daily gains and a highly significant reduction in the amount of dry matter required per kilogram body weight gain.

Unidentified Growth Factor(s) Needed for Optimum Growth of Newborn Pigs

Summary The addition of Reticulogen (a 20-unit anti-pernicious anemia liver extract) to a synthetic milk diet resulted in an increased growth rate in baby pigs over an 8-week period. The final Weights of pigs receiving Reticulogen averaged 19.96 and 21.6 kg as compared with 13.53 and 16.0 kg for those not receiving Reticulogen in two comparisons.

Rate of Utilization of Acetate in the Ruminant.

Summary Yearling lambs which had been trained to wear a face mask were used in experiments to study the metabolism of acetate. The rate of turnover of acetate in the body, that is, rate of acetate influx from the rumen into the blood, its transfer from the blood into other tissues, its conversion into other compounds, and its subsequent appearance as CO2 were measured in 2 sheep. Acetate- 1-C14 disappeared from the body pool with an extremely short turnover time, approximately 3 min., while 50% recovery as expired CO2 required well over an hour. These results indicate the formation of intermediary compounds which turn over much more slowly than body acetate. The calculated acetate flux during the fourth hour after feeding was 9.7 and 10.9 mM/min/sheep, equivalent to 35 and 39 g of acetic acid/hr.

Methylation of t-RNA Effect of Vitamin B12 Deficiency in Rat

Summary Methylation of t-RNA is studied both in vivo and in vitro in rat liver. Addition of either vitamin B12 or DMBC-coenzyme to the in vitro system improves significantly the rate of methyl incorporation from methionine-C14H3. Cold S-adenosylmethionine does not dilute the radioactivity incorporated from serine-3-C14. An alternate pathway of t-RNA methylation involving methyl-B12 is suggested.