published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

Aging results from an accumulation of damage to macromolecules inhibiting cellular replication, repair, and other necessary functions. Damage may be due to environmental stressors such as metal toxicity, oxidative stress caused by imperfections in electron transfer reactions, or other metabolic processes. In an effort to discover medical treatments that counteract this damage, we have initiated a program to search for small molecule drugs from natural sources. We have identified marine red algae as a source of natural products that slow aging of the invertebrate rotifer Brachionus manjavacas. Rotifers are a promising model organism for life extension studies as they maintain a short, measurable lifespan while also having an accepted literature precedent related to aging. Rotifer lifespan was increased 9-14% by exposure to three of 200 screened red algal extracts. Bioassay guided fractionation led to semi-purified extracts composed primarily of lipids responsible for rotifer life extension. The life extending effects of these small molecule mixtures are not a result of their antioxidant capacity; instead they may activate pathways that slow the accumulation of cellular damage. An understanding of how these natural products interact with their molecular targets could lead to selective and efficient treatments for slowing aging and reducing age related diseases.

This thesis documents and discusses the analysis of material properties and pavement performance for Highway 17 and Highway 655 pavement trial sections located in northern Ontario. The object of this work was to compare laboratory-aged material with recovered asphalt cement and to develop an improved chemical aging method that provides asphalt cement that more closely reflects properties after 8-10 years of service. Physical testing of the asphalt cements was done using a bending beam rheometer (BBR) and double-edge-notched tension (DENT) test for laboratory aged material as well as recovered material from the road. The comparison of the regular BBR, extended BBR and elastic recovery test in BBR is also done for the laboratory-aged and recovered material. Two simple modifications to the regular pressure aging vessel (PAV) aging protocol were investigated as possible ways to improve the correlation between field and laboratory material properties. The length of the PAV aging was doubled to 40 hours and the weight for each pan was halved to 25 grams. It was observed that the presently used RTFO/PAV aging protocol does not produce sufficient aging. Hence, the conditions chosen were more severe and therefore are likely to bring the laboratory aging closer to the field aged condition. It was found that both the increase in time and the reduction in weight were able to accomplish the stated objective for most but not all asphalt cements. A separate investigation involved the infrared (IR) analysis of asphalt cements recovered from a large number of contracts in eastern and northeastern Ontario. This study indicated that those asphalts with a largely paraffinic structure (low aromatics index) showed excessive and premature cracking even at lower levels of oxidation (carbonyl index). In contrast, those pavements that were largely spared of thermal distress were constructed with asphalt cements that contained more aromatics (high IR aromatics indices). Aromatics allow the largely aromatic asphaltenes that are formed upon oxidation to remain well peptized rather than flocculated. Peptized asphaltenes allow for good stress relaxation during winter and spring thaw and thus such materials show a reduced tendency for cracking. / Thesis (Master, Chemistry) -- Queen's University, 2010-12-13 11:25:17.522

The purpose of the present study is to recover from selected Hindu and Buddhist texts ideas and images of aging and illumine their historical, semantic and metaphysical dimensions. The results of this endeavor indicate that as cultural adaptive systems, both religion and gerontology share a common concern in seeking to provide aging with purpose and meaning. Further, the internal logic and semantics expressing this relationship in the texts examined are governed by the formal and literary modes of simile, metaphor and myth. The analysis of such age-sensitive concepts as jara (aging), asrama (stages of life), kala (time), parinama (change), karma (determinate actions), kama (desire), and vaja (rejuvenatory and revitalizing force) suggest that the bond between the traditional Indian values of life and gerontology is particularly close and mutual.

In order to increase the number of older adults physically active enough to obtain the health benefits of exercise, inactive individuals must firstly be identified, and attention must then be focused on determinants of exercise amenable to change. This study set out to develop self-complete questionnaires for assessing activity status, and perceived benefits of, and barriers to, physical activity. Of 1456 questionnaires sent out to a random sample of adults aged 55-74 a usable return rate of 37.6% (n=548) was achieved. A principal components analysis of the benefits of physical activity revealed five factors (physical performance, social, weight control, enjoyment, and psychological), and of the barriers to physical activity, also five factors (opportunities, physical exertion, time, limiting health, and support). Alpha internal consistency coefficients for the 10 factors ranged from 0.64 to 0.92, and test-retest reliability coefficients from 0.56 to 0.87. A series of one-way ANOVAs revealed that, with the exception of the benefit weight control, there was a significant gradation in factor scores between active and inactive subjects as classified by 4-, 9-, and 5- point activity classification methods. Validity of the activity classifications was assessed in a subsample of 86 subjects against measures of strength, flexibility, aerobic fitness and objectively measured physical activity. Active and inactive subjects classified using the 4- and 9-point questionnaires differed significantly in 1-mile walk time and energy expenditure estimated by a Caltrac accelerometer. The 5-point questionnaire did not appear able to differentiate active and inactive subjects. Test-retest reliability of the questionnaires ranged from 0.62 to 0.73. The questionnaire developed from this work for measuring perceived benefits and barriers of older adults can be used in either practical or research settings. Further work is required to determine the accuracy of the physical activity questionnaires in identifying low-active individuals in the population.

Thesis (Ph.D.)--Murdoch University, 2006. / Thesis submitted to the Division of Health Sciences. Bibliography: leaves 150-168.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 252-266) Also available in print.

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 117-131) Also available in print.

Thesis PlanB (M.S.)--University of Wisconsin--Stout, 2007. / Includes bibliographical references.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 73-82). Also available via the Internet.