Rats were trained to discriminate an injection of cocaine, 5.0 mg/kg, from an injection of saline, using a two-lever choice paradigm: one lever was correct after cocaine injection, the other lever was correct after a saline injection. After training, cocaine and methamphetamine were generalized to the cocaine lever, but phenethylamine (PEA) was only partially generalized. Cocaine was injected every 8 hrs, 20.0 mg/kg, and the discriminability of 5.0 mg/kg was tested every other day. Redetermination of the cocaine generalization curve after 6 days of chronic administration showed a shift to the right, from an ED50 of 4.1 mg/kg in the pre-chronic condition to 10.0 mg/kg. Tolerance did not develop to the behavioral effects of cocaine, measured by time to the first reinforcement and response rate. There was cross-tolerance to methamphetamine; however, no evidence for cross-tolerance to PEA was obtained. Following the acquisition of tolerance, chronic administration of cocaine was terminated, and the discriminability of 5.0 mg/kg was tested every other day for loss of tolerance. After 8 days the ED50 returned to 5.0 mg/kg.

Wretlind, Heden, and Wadstrom found ammonium sulfate to be inhibitory for the formation of extracellular protease in Aeromonas hydrophila grown in Brain Heart Infusion medium. They demonstrated by manipulating the iron and zinc content within their medium that it is possible to differentially affect the accumulation of hemolysin and protease by A. hydrophila grown in batch culture. Further manipulation of the composition of this medium was done in the present study to determine the effect of other components on the production of protease. The purpose of this study was to determine the factors affecting the level of A. hydrophila protease produced in a chemically defined medium.

The high concentrations of amitriptyline found in blood at autopsy, indicating a large amount of ingested drug, is often contradictory to the prescription available. Using dogs as the animal model it was found that there was a large variance between the dose given and its plasma amitriptyline concentration during the acute phase of absorption. Factors that were found to be important were the amitriptyline to nortriptyline (as metabolite) ratio, the nature of the specimen, and the collection site. The calculation of the dose from an acute ingestion of amitriptyline resulting in death cannot be accurately determined from a single specimen collected at autopsy.