Thesis (M.S.)--University of Michigan, 1958.

Thesis (M.S.)--University of Michigan, 1958.

This study investigated some functional and biochemical characteristics of a bacteriolytic protein in the salivary glands of adult Aedes aecupti. A method for the isolation of this protein from other mosquito salivary gland components is also described. Based on some of its biochemical properties, this bacteriolytic protein can be classified as a lysozyme. This protein is strongly-linked to mosquito sugarfeeding activity because there is a statistically significant (P < 0.05) increase in the levels of lytic activity six hours before mosquitoes start to sugar feed. By its bacteriolytic action, it may function as a protective mechanism against bacteria-contaminated sugar meals. Preliminary work suggests that mosquitoes exposed to lyophilized Micrococcus lysodeikticus in their sugar meal respond by increasing the lytic activity in their salivary glands. The levels of bacteriolytic activity are apparently not affected by bloodfeeding. In the absence of feeding, as in teneral and bloodfed mosquitoes, salivary bacteriolytic activity increases to a maximum, then levels off. This suggests a regulation of the synthesis of this salivary protein that is independent of the feeding state of the adult mosquito. A combination of centrifugation, polyacrylamide gel electrophoresis (non-denaturing and denaturing), cation exchange chromatography and gel filtration, was used to isolate the protein from other mosquito salivary gland components. This salivary protein is lysozyme-like in several aspects: 1) it lyses bacterial cell walls of M. lysodeikticus, 2) it is a basic protein with a pI between 7.47 and 8.89, 3) it is thermostable at low pH, and loses its activity at high pH, and 4) it is composed of one polypeptide chain. Its molecular weight is twice that of hen egg white lysozyme. This salivary bacteriolytic protein is the first insect exocrine lysozyme to be characterized. / Graduation date: 1992

Thesis (M. Sc.)(Biochemistry)--University of Pretoria, 2008. / Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (Ph.D.)(Biochemistry)--University of Pretoria, 2005. / Title from opening screen (viewed March 28, 2006). Includes summary. Includes bibliographical references.

Thesis (M.S.)--School of Dentistry. University of Missouri--Kansas City, 2004. / "A thesis in oral biology." Typescript. Advisor: Carole McArthur. Vita. Title from "catalog record" of the print edition Description based on contents viewed Feb. 23, 2006. Includes bibliographical references (leaves 83-91 ). Online version of the print edition.

published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

No description available.

Introduction: Dental caries is caused by the interaction of the host, oral flora and diet. Stress is one of the host factors implicated. Studies have shown that there is an association between stress and salivary cortisol levels. However, no studies have investigated the relationship between stress, salivary cortisol levels and caries susceptibility. Aims and objectives: The aim of the study was to determine whether there is a correlation between active dental caries, resting and stimulated flow of saliva, salivary buffering capacity, saliva cortisol levels and stress in patients attending a general dental practice in Lenasia South. Methods and materials: Sixty subjects between the ages of 18 and 60 were included in the study. Thirty controls with no active caries, a minimum of 28 teeth and a mean decayed, missing filled surfaces (DMFS) score of 4 or less, and 30 subjects with active caries were included in the study and formed the experimental group. Patients with Sjögren’s Syndrome or connective tissue diseases, on medication that may cause xerostomia, or a history of previous or current irradiation were excluded from the study. At the initial visit resting and stimulated saliva samples were collected and the volume was measured. The buffering capacity and cortisol levels of the resting saliva samples were measured. In addition the Depression Anxiety Stress Scales (DASS) questionnaire was used to determine the stress levels of the participants. The teeth of the subjects with active caries, i.e. the experimental group, were restored. They returned after 4 weeks for a follow up visit and their resting and stimulated salivary flow, buffering capacity of saliva, salivary cortisol and the stress levels were measured. The results were compared using the two sample t test, chi – squared test and a generalized logistic regression analysis. Results: The DMFS of the control group, 0.40 + 0.97, was significantly lower (p < 0.001) than 29.27 + 21.94, in the experimental group. No significant differences were found between the controls and caries prone subjects when the resting flow rates, 0.37 + 0.30 ml/min and 0.32 + 0.19 ml/min; stimulated flow rates, 0.99 + 0.56 ml/min and 0.84 + 0.35 ml/min; buffering capacity of saliva, 19.16 + 4.68 ml 0.01N lactic acid and 21.73 + 9.77 ml 0.01N lactic acid, were compared and the salivary cortisol levels of the controls 17.71 + 22.51 ng/ml, were higher than 11.80 + 14.61 ng/ml in the the caries prone subjects. The DASS scores of the two groups were similar, i.e. 11.33 + 8.48 and 11.2 + 9.6, respectively. After the carious teeth of the caries prone subjects were restored, the flow rate of resting saliva increased from 0.32 + 0.19 ml/min to 0.37 + 0.16 ml/min, the stimulated saliva from 0.84 + 0.35 ml/min to 0.88 + 0.32 ml/min and the buffering capacity of saliva from 21.73 + 9.77 ml 0.01N lactic acid to 22.25 + 7.55 ml 0.01N lactic acid and the salivary cortisol levels decrease from 11.80 + 14.61 ng/ml to 10.00 + 12.12 ng/ml. Again none of these differences were significant. Conclusion: These results suggest that stress levels measured by the DASS questionnaire may not be related to caries. A less subjective questionnaire may find a relationship between salivary cortisol levels, stress and dental caries.

Thesis (M.Sc.D.)--Boston University School of Graduate Dentistry, 1965. Periodontology. / Bibliography included.