A method for hyperthermic treatment of mouse skin.

The Sencar mouse skin system is a recognized model for tumour initiation, promotion and progression. The current interest in the effect of hyperthermia on this multi-stage tumorigenesis model prompted the need for a technique to accurately heat a section of dorsal skin of a large number of mice for 30 min per heat treatment. In the technique described, experimental groups of 25 female Sencar mice were treated at 7-8 weeks of age under general methoxyflurane anaesthesia.

Hyperthermia and phorbol ester tumor promotion in mouse skin.

In a two-stage skin tumorigenesis protocol [7,12-dimethylbenz[a]anthracene (DMBA) initiation followed by twice weekly 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion], SENCAR mice developed an average of approximately 8.5 papillomas per animal. Hyperthermia treatments of the initiated skin (44 degrees C, 30 min) immediately before or after each TPA application (for 90 days) reduced papilloma frequency 80-90%.

Fluorometric method for rapid detection of DNA strand breaks in human white blood cells produced by low doses of radiation.

DNA strand breaks can be detected with great sensitivity by exposing crude cell lysates to alkaline solutions and monitoring the rate of strand unwinding. As little as one strand break per chromosome can be detected. Previous methods for measuring strand unwinding have required physical separation of single- from double-stranded molecules.