No description available.

Thesis (Ph. D.)--University of Missouri--Columbia, 2001. / "December 2001." Typescript. Vita. Includes bibliographical references (leaves 153-159). Also available on the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Columbia University. / Vita. Bibliography: p. 40-41.

No description available.

No description available.

Thesis (M.S.P.H.)--University of Michigan, 1939.

Thesis (M.S.P.H.)--University of Michigan, 1939.

Several short-term assays are in use to assess the carcinogenic hazard of chemicals. While the ability to induce initiating events that may lead to carcinogenesis is measured, compounds and conditions that might modify the ability of chemicals to cause those initiating events are not assessed by such tests. In addition, compounds that affect the ability of cells to react in a normal fashion to the damaging action of carcinogens are not detected by these methods. Shifts in alkaline sucrose gradient profiles of centrifuged DNA (as an indication of DNA fragmentation) and formation of aryl and alkyl DNA adducts (as an indication of DNA modification) have been used as short-term assays for carcinogenic and mutagenic potential. Repair of DNA damage has been measured by restoration of near-control sedimentation profiles of DNA and the loss of aryl and alkyl adducts over time after damage or modification of DNA by carcinogens and mutagens. In this study, the ability of sodium ascorbate to modify the DNA fragmenting and adduct-forming action of the carcinogens N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and benzo(a)pyrene (BP) was investigated. In addition, the ability of cells In vivo and In vitro to repair DNA in the presence of sodium ascorbate was assessed by the two methods described above. It was found that sodium ascorbate inhibited repair in vivo and in vitro. In addition, sodium ascorbate was found to fragment DNA in vivo and in vitro in the presence of copper, and to inhibit the action of carcinogens _in vivo and in vitro by nucleophilic scavenging of electrophilic carcinogens. Sodium ascorbate was also found to inhibit the binding of BP to DNA jLn vivo and In vitro. On the other hand, other reducing agents had other effects. Propyl gallate (a sulphydryl reducing compound) inhibited binding of BP to DNA in vitro, but enhanced binding of BP to DNA in vivo. The sulphydryl reducing agent glutathione enhanced binding of BP to DNA in vivo and in vitro. Alkaline sucrose gradient analysis of DNA damage and recovery from that damage, and BP adduct formation in DNA and disappearance over time, appear to be suitable methods for assessment of the modifying properties of compounds and conditions on the initiating events that may lead to mutation or carcinogenesis. / Medicine, Faculty of / Medical Genetics, Department of / Graduate

Indiana University-Purdue University Indianapolis (IUPUI) / The effects of additional citrus fruit in the diet on the periodontium have been a debated subject for some time. This study attempted to measure the effects of eating three additional oranges per day by 123 children ages six through twenty years and an equal number of controls over a 23-week period. To measure any changes that might take place, the following were evaluated clinically, and the decayed, missing and filled surfaces were also evaluated radiographically: 1. gingival status 2. plaque formation 3. D.M.F.S. and d.m.f.s. 4. white spots Results after the 23 week test period showed that the gingival scores increased significantly in both groups (increased inflammation). The plaque formation score also increased in both groups, but only the non-orange eaters' score increased significantly over their original score and over the orange eaters' score. The decayed, missing, and filled surfaces and white spots did not change significantly in either group. Therefore with this study sample over the 23-week test period, the additional oranges in the diet had limited measurable effect on the hard and soft tissues of the oral cavity.