Previous research studies have indicated that coffee brew and water extracts of heated brown food systems such as molasses, beef, prunes and raisins have an inhibitory effect on carcinogen-induced mutagenicity in the Ames Salmonella strains. A hypothesis to explain these observations is that carcinogens are adsorbed onto water-insoluble complexes in coffee brew and melanoidins in heat-treated foods. The present study was undertaken to characterize the water-insoluble fraction (WIF) from reconstituted instant coffee powder; to examine the genotoxic inhibitory effect of the WIF and browning reaction melanoidins; to determine the degree and type of binding of benzo(a)pyrene (BP) and afla-toxin B₁ (AFB₁) by the water-insoluble fraction; and to assess the effect of a model system melanoidin (MSM) on the inhibition of BP induction of aryl hydrocarbon hydroxylase (AHH) in the small intestine of rats. WIF was separated from reconstituted spray dried coffee by precipitation of particulate matter with ethanol at a 90% level and was further purified by resuspension of the precipitate in water and subsequent centrifugal sedimentation. The yield of WIF was about 3% of the instant coffee powder (1.4% moisture). From the non-metallic elemental analysis of WIF, the empirical formula C₄₇H₇₉O₄₁N, was determined. The ratio of C, H, and O atoms suggests the presence of carbohydrates and the nitrogen atom implies the presence of amino acids. The molecular weight of WIF was estimated to be around 200,000 as determined by a column chromatographic technique. A variety of inorganic elements were found in WIF, with potassium in the highest concentration Phenolic compounds, reductones and amino acids were found in WIF. Phenolic compounds were detected by a semiquantitative FeCl₃ colorimetric method which indicated that these compounds were present at a level of 4 mg of caffeic acid equivalent per 10 mg of WIF. The reductone content of WIF was about 140 mg ascorbic acid equivalent per g. Eleven amino acids were identified in the acid hydrolyzate of WIF. The major amino acids were: aspartic acid, glutamic acid, glycine, valine, isoleucine and histidine. Dubois et al. (1956) sugar analysis indicated that 56% of WIF consisted of carbohydrates. Analysis of acid-hydrolyzed WIF by paper chromatography, gas liquid chromatography and GLC-mass spectroscopy indicated that mannose, galactose, glucose and arabinose were the major monosaccharides. Gas liquid chromatography-mass spectrometry showed that the carbohydrates in WIF hydrolyzate were mostly simple hexose sugars with trace amounts of deoxy-sugar fragments, but no N-acetyl glucosamines were identified. The Ames Salmonella test was employed to assess the genotoxic inhibitory effect of coffee WIF and model system melanoidin (MSM) on benzo(a)-pyrene (BP), afiatoxin (AFB₁) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The reverse mutation frequencies were reduced in the presence of WIF and MSM over a range of dosages. Studies were conducted to examine the effect of pH on the binding ability of WIF with BP and AFB₁. A maximum binding of about 83% of BP by WIF in buffer at 37°C was achieved at pH 2.0, and approximately 63% binding of BP by WIF occurred at pH values ranging from 4 to 9. The binding of AFB₁ by WIF in buffers at pH values between 2 to 9 ranged from 47 to 55% at 37°C. A pH effect on afiatoxin B₁ binding to WIF was not apparent. Binding of BP by WIF in citrate buffer (pH 3.0) was examined by column chromatography using different eluants to try to determine the type of binding. The BP peak coincided with the WIF peak when citrate buffer was used (pH 3.0) with and without added NaCl, urea and mercaptoethanol. With SDS added to the citrate buffer eluant, WIF was broken down into smaller particles yet retaining most of the BP. Hydrophobic bonds are presumably involved in the binding of BP to WIF. The activities of aryl hydrocarbon hydroxylase (AHH) in the microsomes of the small intestine of rats fed diets with or without BP and with or without MSM were assessed. The AHH activity for rats on a diet containing both BP and MSM was significantly smaller than that for rats on a diet with BP and no MSM. Components of MSM presumably bind BP to the extent that less BP was available for induction of AHH activity. / Land and Food Systems, Faculty of / Graduate

Diesel exhaust emissions were collected from a 2 litre direct injection diesel engine using the Total Exhaust Solvent Scrubbing Apparatus (TESSA). Emission samples were collected from a series of two minute engine runs, at a variety of engine speeds and loads which covered the full operating range of the engine. The exhaust extracts collected were then tested for their cytotoxicity and mutagenic potential in cultured Chinese hamster cells. Emission samples were found to be extremely toxic, with most causing 100% cytotoxicity at concentrations of less than 100 /µg/ml. Chromosome aberration studies indicated that less than 50% of the emission samples collected induced increases in the numbers of cells with aberrations, and less than 10% induced aberrations in cell cultures exposed to emission samples with a supplementary metabolic activation system. Samples tested in in vitro sister chromatid exchange assays, induced significant increases in the frequencies of exchanges. Linear trend statistics calculated from chromosome aberration data, were used to reflect the relative clastogenic potential of individual emission samples. Linear regression of these trend values against physical components of the exhaust emissions, showed a significant correlation between sample mutagenicity in aberration assays and the emission of oxides of nitrogen (NOx) in the exhaust. Mapping of NOx emissions to engine conditions has shown that the mutagenicity of diesel emissions from the test engine tend to be highest under condition of low speed/high load and high speed with increasing load. Toxicity assays of subfractions of emission samples isolated by column chromatography has shown that the toxicity of the emission samples is associated with the aromatic and polar components of the samples. The dose responses obtained from mutagenicity assays, in which samples only caused increases in aberrations and chromatid exchanges at the same concentrations at which cytotoxic effects were observed, suggests that the emission may have a limited cytogenetic effects in vivo. Mapping of the clastogenicity of emission samples against engine speed and load, has shown that the most clastogenic samples collected, were emitted under engine conditions that might be expected to occur under urban driving conditions. Results of epidemiological studies of health effects of diesel emissions, and recent associations between particulate emissions and health effects are discussed.

Thesis (Ph. D.)--Virginia Polytechnic Institute, 1955. / Vita. Abstract. Includes bibliographical references (leaves 127-131). Also available via the Internet.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (p. [119]-124).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains xi, 107 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 98-107).

No description available.

Photocopy of typescript. / Digitized by Kansas Correctional Industries

Temperature influences the incidence of chemically induced cancer in fish, with warmer temperatures being associated with higher cancer incidence. The mechanisms of temperature-modulated chemical carcinogenesis in fish, however, have not been described in detail. Therefore, one primary objective of this study was increased understanding of how temperature-modulated genotoxicity of 7,12- dimethylbenz(a)anthracene (DMBA) corresponded with tumor response. The second entails the potential of temperature to modulate cancer promotion. Rainbow trout (Oncorhyncus mykiss) (2 g) were acclimated at 10, 14 or 18��C for one month and then exposed to 1.0 ppm DMBA in their water for 20 hr. Exposures were at respective acclimation temperatures or 10 and 18��C acclimated fish were shifted to 14��C for DMBA exposures. Adduction of [��H]DMBA to hepatic DNA 21 days after exposure was higher in 10��C than 18��C fish exposed at their respective acclimation temperatures. However, in fish shifted to 14��C, the concentration of hepatic [��H]DMBA DNA adducts was similar in 10��C and 18��C acclimated fish at that time. Temperature effects on tumor incidence were assessed 9 months after DMBA waterborne exposures. Incidence of stomach, liver and swim-bladder cancer increased with rearing temperature. Differences in tumor incidence were less marked in fish reared at the same temperature (14��C). Retrospective analyses of livers from a tumor study initiated with aflatoxin B1 (AFB1) was conducted with antibodies to endogenous proliferating nuclear antigen (PCNA). Proliferating cells were scored by counting labeled nuclei in 5 random 10x fields using an image analysis program (BIOQUANT SYSTEM IV). There was no significant increase in numbers of PCNA labeled hepatocytes with temperature. The influence of acclimation temperature on plasma mitogens that stimulate cell division was assessed in cultured Chinook salmon embryo cells (CHSE-214). Plasma from rainbow trout (120-150 g) acclimated to either 10 or 18��C for at least four weeks stimulated in vitro proliferation of CHSE-214 cells to the same extent. This study demonstrated that chemically induced tumors in fish were modulated by temperature not only through genotoxin disposition and formation but also through persistence of DNA adducts. It also discounted the role of mitogenesis in temperature-modulated chemical carcinogenesis. / Graduation date: 1996

No description available.