Thesis (Ph. D.)--University of Wisconsin--Madison, 1953. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Call number: LD2668 .T4 1961 K59

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Aryl hydrocarbon hydroxylase (AHH) was induced 15-fold in Ambystoma tigrinum by intraperitoneal injection of 3-methylcholanthrene in corn oil, or 10-fold by addition of aromatic polycyclic hydrocarbons to the aqueous environment of the neotene animal. The cytochrome P-450-associated microsomal enzyme is similar to the inducible, one-gene, autosomal-dominant system typical in the laboratory mouse and man. Differences in optimal temperature for enzyme induction and activity were noted in organ culture of human and Ambystoma tissues, and ratios of benzpyrene metabolites differed between Ambystoma and Mus. The half life of enzyme activity induced in vivo was related to the excretion of hydrocarbon metabolites.

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The fatty acid composition of whole tissue and plasma membrane fractions of mammary adenocarcinomas and normal mammary glands excised from Strong A female mice fed a 15% safflower oil and 15% tallow diets were studied. Previous work has indicated that high fat diets in general and high unsaturated fat diets in particular, influenced tumorigenesis. The mechanism is not clear. Alternig the normal composition and structure of the plasma membrane can result in altered physiological responses.The fatty acid composition of the dietary fat used in this study affected the fatty acid distribution of mammary gland tissue to a greater degree than tumor tissue. Tumor tissue had almost twice the percentage of linoleic acid as normal tissues (17.0% vs. 9.2%). Oleic acid was also elevated in tumor tissue (24.5% vs. 10.9). The normal tissues contained significantly higher proportions of eicosatrienoic acids (13.5%, 12.2%) than did tumorous tissues, regardless of diet (5.8%, 1.1%). It may be that some of these prostaglandin-active fatty acids in tumorous tissues have been diverted into prostaglandin synthesis.Results of this study indicate that the effect of dietary fat on plasma membranes of tumor cells and normal mammary gland cells was minimal. The saturated or unsaturated state of the fatty acids in the diet appear to play a role in the genesis of tumors by changing the availability of linoleic acid and other prostaglandinactive fatty acids.

Metaphase chromosome aberrations were studied in cultured embryonic Syrian hamster cells after exposure to one of two potent mutagenic chemicals in combination with Adenovirus 12. The cultured cells were grown in Minimal Essential Medium supplemented with fetal calf serum. All cells were retained in Arginine Deficient Medium during treatments. Exposure to 4-nitroquinoline-1-oxide (4NQO) was followed at various intervals by Adenovirus 12 infection. Various concentrations of N-methyl-N¹-nitro-N-nitrosoguanidine (MNNG) were either followed or preceded at different time intervals by Adenovirus 12 infection. In all instances the rates of metaphase plates with chromosome abnormalities after combination treatments were approximately equal to the sums of the rates of abnormal plates induced by similar concentrations of each agent independently. A small proportion of the metaphase cells with chromosome abnormalities characteristic of both agents was observed, however, after combined treatments. The relationships between the rates and types of chromosome abnormalities induced by combination treatments and the rates of cell transformation as observed elsewhere but induced by similar treatments, are discussed. The rates of metaphase chromosome abnormalities induced by MNNG in virally transformed embryonic Syrian hamster cells were also investigated. It was found that these rates were simply equal to the sums of the rates of chromosome abnormalities induced by MNNG in the nontransformed control cultures plus the spontaneous rates of chromosome abnormalities in the transformed hamster cells. The significance of these findings are also discussed. / Science, Faculty of / Zoology, Department of / Graduate