Jack R. Leonards

A study on the equivalence of metabolic patterns in rat adipose tissue: Insulin versus glucose concentration

Abstract The rat epididymal fat pad has been incubated with increasing concentrations of glucose. The metabolic patterns obtained in the absence and presence of insulin are quantitatively different in several respects. In particular, insulin appears to stimulate glycogen synthesis, the oxidation of carbon 1 of glucose to CO 2 and fatty acid synthesis, while increasing glucose concentrations favor the oxidation of carbon 6 of glucose to CO 2 and the synthesis of glycerol from glucose. The mechanism of action of insulin in adipose tissue is considered in the light of these observations. It is suggested that insulin action on glucose permeability or activation alone does not adequately explain the patterns observed.

Artificial Kidney. II. Construction and Operation of an Improved Continuous Dialyzer.

Summary An improved type of continuous dialyzer specifically designed for use as an artificial kidney has been described. A thin film of blood is made to flow between 2 sheets of cellophane supported between rubber pads which are grooved to allow passage of a dialyzing solution. Details of its operation are given and its application in the treatment of acute renal insufficiency in dogs is described.

Presence of acetylsalicylic acid in plasma following oral ingestion of aspirin.

Summary The absorption and hydrolysis of aspirin has been examined under various experimental conditions. Aspirin appears to be absorbed intact from the gastrointestinal tract. High concentrations of acetylsalicylate in the plasma can be demonstrated following oral ingestion of soluble but not insoluble aspirin preparations. This is correlated with the increased rate of absorption of the soluble products. There appears to be a rapid hydrolysis of acetylsalicylate in vivo and it is suggested that the principal site of this hydrolysis is the tissues. Direct evidence for hydrolysis of acetylsalicylate to salicylate by the liver of the dog has been demonstrated.

Use of Artificial Kidney for Removal of Barbiturates in Dogs.

Summary An artificial kidney of the Skegg-Leonards type was used successfully to lower blood barbiturate levels in dogs. Approximately 15 to 25% of the intravenously injected pentobarbital, 35% of intravenously injected amobarbital, and 40 to 70% of intra-peritoneally injected phenobarbital were recovered in the respective dialysates. This therapy was life saving in the phenobarbital experiments, of some value in the amobarbital intoxication, but of questionable value in pentobarbital poisoning.

A Method for Continuously Recording the Disappearance of Radioactive Tracers from Circulating Blood

A method of continuous recording of the disappearance of radioactive materials from the circulating blood is described. By cannulation of the right femoral artery of dogs and leading the tubing past a scintillation counter into the right femoral vein a complete circuit is established in which the concentration of radioactivity may be continuously monitored. Curves showing concentration of the radioactive material versus time have been obtained following injection of iodinated (I131) plasma, Na24, I131, P32, K42, and colloidal Au198. No errors are introduced by sample withdrawal, timing of samples, or geometric variations.

The preparation and storage of cytochrome oxidase.

Abstract The preparation of cytochrome oxidase by the method of Keilin and Hartree has been modified to give an increased yield and activity of the enzyme. The enzyme can be dried from the frozen state and stored for more than a year provided it is reconstituted in pH 9.5 buffer and treated with sound waves at 9,000 cycles/sec. This material is “soluble” in that it resists centrifugation at 11,000 × g for 2.5 hr. Its “solubility” depends in no way on autolysis of the heart muscle prior to extraction of the enzyme.

Ineffectiveness of in vivo Dialysis in Prolonging Life in X-Irradiated Dogs.

Summary and Discussions Dogs given 500-550 r whole body x-irradiation were subjected to an in vivo dialysis of their blood during the early post-irradiation period. No improvement in the survival of these animals was noted. When applied 0.5-3.0 days after irradiation, the dialysis procedure caused a slight decrease in the average survival time, as compared to sham-dialyzed controls. The results tend to minimize the importance of readily dialyzable “toxins” in the lethal action of x-irradiation.

A new endpoint for blood pressure determination in the rat's tail.

Summary A new endpoint for the indirect measurement of systolic blood pressure in the caudal artery of the rat has been described. The change in volume of the rats tail which occurs when the pressure in an inflated cuff at the base of the tail is allowed to drop to arterial pressure is mechanically transferred to develop pressure on a carbon telephone transmitter button. The electrical resistance of the button is continuously observed, a decrease in resistance indicating the endpoint for the blood pressure measurement.

Effect of penicillin on blood urea in the rat.

Summary The intraperitoneal injection of penicillin into adult albino rats had no significant effect on the blood urea level, even when doses as high as 500,000 Oxford units were administered per kg of body weight.