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Biomedical subjects

R L Nelson

Publications and source records attributed to R L Nelson.

At least 199 records · Page 11Linked to original sources
PubMed1971

Transformation of hamster cells in vitro by polycyclic hydrocarbons without cytotoxicity.

Treatment with either a flavone or benz(alpha)anthracene before the addition of a potent carcinogen, benzo(alpha)pyrene or 3-methylcholanthrene, enhanced the transformation of Syrian hamster cells that are seeded in order to form colonies. 7,8-benzoflavone and benz(alpha)anthracene prevented the cytotoxicity by the carcinogens, while 5,6-benzoflavone did not. The results clearly indicate that it is possible to dissociate the transforming from the toxic metabolic properties of benzo(alpha)pyrene and 3-methylcholanthrene.

Animals↗
PubMed1971

X-irradiation enhancement of transformation by benzo(a)pyrene in hamster embryo cells.

The addition of benzo(a)pyrene to cells obtained from Syrian hamster embryo cultures that had been plated to produce discrete colonies resulted in transformation. Altered colonies were not seen in controls. Prior irradiation of hamster embryo cells increased the transformation by benzo(a)pyrene, both per cell and per total colony. Maximum enhancement occurred when benzo(a)pyrene was added 48 hr after irradiation. Enhancement was greatest after 250-500 R, and decreased with higher doses of radiation. The addition of benzo(a)pyrene 72 hr after irradiation resulted in very little enhancement. Although transformation increased with benzo(a)pyrene concentration, enhancement was independent of concentration within the range used. No colony with transformed morphology was recognized among the colonies of normal cells that survived irradiation.

Animals↗
PubMed1969

Sarcoma-producing cell lines derived from clones transformed in vitro by benzo[a]pyrene.

Cells derived from mixed Syrian hamster embryo cultures were treated with pyrene (control) or with benzo[a]pyrene. Transformed clones were obtained only with the carcinogen. Some of the transformed clones were responsible for cell lines that produced tumors when injected into hamsters. These observations provide evidence that chemical-induced oncogenesis can be studied by an in vitro model.

Animals↗
PubMedDate not supplied

Diet and adenomatous polyp risk.

Studies of risk factors for colonic adenomatous polyps have been reported in greater numbers in 1993 than in all previous years combined. This explosion in interest in polyps has not arisen because polyps themselves cause serious illness. They are in the vast majority of cases asymptomatic. However, adenomas have become the surrogate for colon cancer in a number of phase III dietary intervention trials. These trials were undertaken at a time when very little was known of adenoma risk factors. Data accumulated in the past 18 months in general demonstrate a similarity in risk factors for cancer and polyp. Since it has also been recently established that polypectomy diminishes colon cancer risk, the adenomatous polyp has been established as an ethical and convenient surrogate for cancer of the colon. Prevention of colorectal cancer is the goal of all the above studies, and it is hoped that the dietary intervention trials currently under way will generate the data that will make prevention possible.

Adenomatous Polyps↗