Donald E. Rounds

Enzyme inactivation with ultraviolet laser energy (2650 Angstroms).

Inactivation of rat heart lactate dehydrogenase was accomplished by irradiation of the enzyme in solution with a frequency quadrupled neodymium glass laser.

Prospects for a personal screening method for cervical carcinoma

Abstract Biopsies were obtained from human cervices which represented normal tissues, dysplasias, carcinoma in situ , localized carcinomas, and invasive carcinomas. Nonmalignant tissues produced relatively small amounts of DNA, associated with a ring-shaped particle (RSP), during a 24-hr incubation period, while malignant tissues produced relatively large amounts of RSP and DNA. An analysis of DNA in balanced salt solution, which had been used to irrigate cervices in situ , indicated that a similar DNA-metaplasia relationship exists for cervical tissues in vivo . This observation suggested that semiautomation of DNA quantitation of cervical irrigation specimens could form the basis of a personal screening method for cervical carcinomas.

The effect of laser power at 2650 A on deoxyribonucleic acid

Abstract A study was conducted to determine the effect of laser power at a wavelength of 2650 A on template activity of calf thymus DNA. It was observed that template activity decreased exponentially with increasing U.V. laser exposures and that U.V. laser-treated DNA inhibited the activity of non-irradiated DNA. The optical density of the treated DNA showed less than 7% decrease at 2650 A. Although these results were qualitatively similar to those reported for conventional U.V. effects, there was a suggestion of a lack of reciprocity using the high peak powers of the U.V. laser.

Laser photosensitization and metabolic inhibition of tissue culture cells treated with quinacrine hydrochloride

In a preliminary report (1) it was suggested that nucleolur function could be probed by treatment of tissue culture cells with quinacrine hydrochloride followed by laser microirradiation. Apparently the quinacrine associates selec tively with the nucleolus, thus making this organelle susceptile to selective damage by laser microirradiation. If the laser technique is to be useful for studying nucleolur function, the metabolic effects of the photosensitizing agent (quinacrine) must be elucidated. In addition, since previous studies have suggested shifts ïn absorption characteristics of other amino acridines (2) when bound in vitro, it is important to determine if such shifts occur with quinacrine. This is particularly important in selecting the appropriate wavelengths for microirradiation. In this manuscript we will present data : (a) indicating the quinacrine hydrochloride has only a temporary effect on nucleolur function ; (b) on the in vitro absorption spectrum of quinacrine hydrochloride. Materials and Methods Ce11s utilized were the CMP line of human adenocarcinoma cells (3). For metabolic studies all cells were seeded into Leighton culture tubes, 100,000 cells per tube, and incubated for 48 hours at 37oC in Eagles medium supplemented with lOX fetal calf serum, penicillin (100,000 IU/cc), and streptomycin sulfate (0 .25 mg/1). After 48 hours of growth, the medium was removed and quinacrine 1081

MEASUREMENT OF THE CELL MIGRATION INDEX WITH A HENE LASER

Human diploid fibroblasts (WI38) were inoculated into Rose multipurpose culture chambers, using a high population density to develop confluency. After 24 hours, cells from a 1 mm swath were scraped from the center of the chamber. This cleared path was positioned to permit an unobstructed transmission of a 0.9 X 20 mm beam of light from a 1 mW HeNe laser. As cells migrated, at 37 degrees C, into the path of the laser beam the light scatter was recorded, using a photomultiplier tube. Because the amount of light scatter was proportional to the number of cells migrating into the beam, the system measured the migration index of the cells. Slight variations in the design of this device could facilitate data collection during surveys of toxic agents, fertility tests, and delayed hypersensitivity.