Paul F. Fenton

Effect of Diet on Obesity of Yellow Mice in Inbred Lines.

Summary and conclusions 1. The observation has been confirmed that yellow mice on continued inbreeding no longer become obese if maintained under the usual laboratory conditions. 2. Feeding a diet of the “synthetic” type made it possible to induce obesity in the yellow mice but not in their non—yellow litter—mates. 3. The obese yellow mice were observed to have fatty livers. Two of these animals were found to have liver tumors.

Nutrition and Genetics

Readers of Postgraduate Medicine will recall that in the article which introduced this series in January 1959 we said, “The introduction of longer duration in nutritional problems re-emphasizes the fact, known by experienced physicians since Hippocrates, that to understand how a given disease affects a given patient one must consider not only the disease agent but also the patients individual constitution. Recent trends emphasize the importance of studying the interaction of the constitutional and nutritional factors.”Few research scientists have done work as fundamental in this field as that of Professor Fenton. His work on differential nutritional requirements of various strains of mice, conducted at Yale University in the 1940s, encouraged the more enlightened nutritionists to think of nutrition not as the discipline concerned with diet and its physiologic effects but, more accurately, as that branch of physiology concerned with the interaction between the nutritional environment and the genetic const...

Response of X-Irradiated Mice to Intravenous Inoculation of Intestinal Bacteria.

Summary Intravenous inoculation of mice with Proteus following moderate total body X-irradiation caused a marked increase in mortality and a much shorter median death time compared to control animals injected with saline. A severe bacteremia existed before death in these animals. Non-irradiated mice given the same inoculum of Proteus quickly reduced the number of bacteria in the blood with eventual complete clearing. No deaths occurred among these animals. Bacteremia caused by organisms common to the intestinal tract frequently occurred in the mice which died following irradiation and saline injection.

Muscle and liver glycogen of mouse strains susceptible or resistant to nutritionally induced obesity.

Muscle and liver glycogen levels of mice differing in their susceptibility to nutritionally induced obesity were studied in relation to inherited differences in metabolic and endocrine patterns. The I/Fn strain, resistant to nutritional obesity, is characterized by a muscle glycogen level four to six times higher than those of strains which can be made obese. The liver glycogen of the I strain mouse is significantly lower than those of the other strains. Muscle glycogen levels were found to reach a maximum at about 6 months of age in all but one of our strains.

Lipid metabolism of two highly inbred strains of mice.

Summary Differences in the metabolism of 2 highly inbred strains of mice were studied. There was a higher level of FFA in the plasma of the A/Fn strain mouse as compared to the I/Fn, although measurements of FFA release in vitro revealed no differences in the rate of mobilization per unit weight of adipose tissue. Ketone body production by liver slices was greater in the I, and in both strains was inversely related to the hepatic glycogen content. Tripalmitin-C14 oxidation to C14O2 in vivo was more marked in the I than in the A, while fat retention was greater in the A. The simultaneous feeding of a 25% glucose-50% starch solution markedly depressed CO2 output from tripalmitin in the I strain and caused an enhanced output in the A.

Glucose Absorption in Highly Inbred Strains of Mice.

Conclusions 1. Glucose absorption in the mouse has been studied. Increasing the concentration of administered solution results in an increase in the amount of glucose absorbed. 2. Glucose solutions of 75% concentration were absorbed somewhat more readily by mice of the C57 strain than by those of the A strain (p = 0.015). 3. Administration of 25% glucose solutions leads to some diminution of the phosphatase activity of the small intestine determined both chemically and cytochemically.

Nutrition of the Mouse. XII. Comparison of Several Salt Mixtures.

Summary Five salt mixtures were tested for their ability to support growth as well as fat and mineral deposition in the carcass. Feeding the mixture described by Hubbell, Mendel and Wakeman(1) resulted in significantly higher ash values than when the other four mixtures were employed. Increasing the Ca:P ratio of the Fenton-Carr mixture(4) significantly improved mineral deposition.