published_or_final_version / Zoology / Master / Master of Science

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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.

No description available.

No description available.

<p>'Endocrine disrupting chemicals (EDCs) are compounds found in the environment that have the potential to disrupt normal endocrine function. Estrogenic EDCs (e-EDCs) is a subclass of EDCs and is defined as substances contaminating the environment that may mimic or inhibit the effect of endogenous estrogen and therefore may influence developmental and reproductive health in humans and animals. The aim of this study was to develop, validate and implement a battery of in vitro and in vivo screening assays for e-EDCs. The study was concluded by implementing this battery of assays to assess the Eerste River, South Africa at three sampling sites, namely Jonkershoek, Stellenbosch sewage treatment works (STW) effluent and Spier for e-EDCs. The control site, Jonkershoek contained very low levels of estrone. Water from this site showed no estrogenic activity when the E-screen and the ER_ induction in MCF-7 cells. Some of the water samples collected at this site tested positive for estrogenicity when analysed with the juvenile tilapia VTG assay, whereas the rest were negative. The estrone levels in the sewage effluent extracts as well as Spier were significantly higher. The assay using ER_ protein induction by the MCF-7 cell line, the MCF-7 proliferation assay and the tilapia in vivo screen for estrogenicity showed that these samples are estrogenic. Results obtained for estrogenicity at the three different sampling sites for each of the assays in the battery were comparable. In this study we developed, validated and also implemented a battery of assays encompassing both in vitro and in vivo assays, based on different biological mechanisms, to detect estrogenic EDCs. To our knowledge, this is the first study that has used a battery of bioassays to specifically assess a South Africa river for estrogenicity...'</p>

Thesis (M.S.)--University of Toledo, 2009. / Typescript. "Submitted as partial fulfillment of the requirements for the Master of Science in Biology." "A thesis entitled"--at head of title. Bibliography: leaves 54-65.

Thesis (Ph. D.)--University of Hong Kong, 1987.