George Yerganian

Maintenance of Normal in situ Chromosomal Features in Long-Term Tissue Cultures

Clonal isolates from a rapidly proliferating fibroblast-like derivative have retained the classic diploid chromosome relationship over a period of many transplant generations. The readily identified members of the 11 pairs of chromosomes, including the sex chromosomes (X1 and X2), have aided in localizing minute structural alterations within recloned diploid and aneuploid sublines.

Spontaneous Hereditary Diabetes Mellitus in Chinese Hamster (Cricetulus griseus). 1. Pathological Findings.

Summary Spontaneous diabetes mellitus, as observed in Chinese hamsters, has been described and compared with diabetes in human and experimental animals. Evidence was cited that in Chinese hamsters, the disease is genetically determined. Certain inferences were drawn as to the importance and significance of this observation for the future study of inheritance of diabetes, screening of hypoglycemic agents in the Chinese hamster, and metabolic studies.

Induction of tumors of the stomach and esophagus in inbred Chinese hamsters by oral diethylnitrosamine.

Summary Inbred Chinese hamsters receiving 40 ppm diethylnitrosamine in their drinking water over a period of 17–26 weeks developed papillary growths of the esophagus and forestomach in all of the animals. In these lesions, squamous carcinoma was found in 23% of the stomach tumors and in 15% of esophageal growths. Hepatomas occurred in 13% of the animals and hepatic cirrhosis in 60%. Explantation of cirrhotic liver tissue in culture gave an epithelioid cell line with a pseudodiploid karyotype, 2n = 22. The highly inbred Chinese hamster appears to be a suitable model for studies involving carcinogenesis in the esophagus and stomach.

Latent Meiotic Anomalies Related to an Ancestral Exposure to a Mutagenic Agent

When urethan is administered to cytologically normal F2 progeny descended from grandsires exposed to ethyl methanesulfonate, meiotic anomalies in the forms of site-specific X-chromosome deletions and bivalent associations are noted in spermatocytes of male Armenian hamsters examined 6 and 8 days after treatment, respectively. These latent anomalies are initiated and retained in a premutated state for two generations after the ancestral exposure to ethyl methanesulfonate, the additional impetus required to complete the mutational processes being supplied by urethan.

STUDIES IN STRESS GLYCOSURIA. I. PROLONGED GLYCOSURIA IN CHINESE HAMSTERS AFTER REPEATED STRESS.

Chinese hamsters, unfamiliar to each other, were briefly placed together daily for several weeks. This resulted in fighting and stress. The stress groups were arranged in such a way that no animal met the same animal within any five-day period. A gradual increase in the incidence of positive urine glucose occurred in the experimental animals but not in the nonfighting controls. Glycosuria continued for two to twelve weeks following the termination of the prolonged regimen of daily repeated stress periods. These findings are an extension and amplification of those reported by Cannon and his group. The results may have significance in exploring the relationship of emotional stress to diabetes mellitus.