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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
711

Subcortical Hyperintensities in Alzheimer's Disease and the Elderly: An MRI-based Study Examining Signs of Cerebrovascular Disease and Dementia

Ramirez, Joel Roy 19 December 2012 (has links)
Subcortical hyperintensities (SH) are believed to be observable signs of cerebrovascular disease, indicating some form of subcortical vasculopathy. Also commonly referred to as leukoariosis, these hyperintense signals on proton density, T2-weighted and fluid attenuated inversion recovery magnetic resonance images, are commonly observed phenomena in Alzheimer’s disease patients and elderly persons. Several SH sub-types with differential brain-behavior associations have been proposed in the scientific literature: periventricular, deep white, cystic fluid filled lacunar-like infarcts and perivascular Virchow-Robin spaces. This study will present Lesion Explorer (LE): a comprehensive tri-feature MRI-based processing pipeline that effectively and reliably quantifies SH sub-types in the context of additional brain tissues volumetrics in a regionalized manner. The LE pipeline was validated using a scan-rescan procedure. Finally, the LE pipeline was applied in a cross-sectional study of Alzheimer’s disease patients and normal elderly controls. Brain-behavior relationships were demonstrated with regional SH volumes and executive functioning, speed of mental processing, and verbal memory.
712

The Effect of Acute Eccentric Treadmill Running on NF-κB Activation and HSP72 Content in Skeletal Muscle from Late Middle-aged Rats

Lewis, Evan 14 December 2011 (has links)
Eccentric exercise causes skeletal muscle damage, yet the acute cellular responses post-exercise have yet to be fully elucidated. To better understand the post-exercise response, heat shock protein (HSP) 72 content and nuclear factor-κB (NF-κB) activation where examined in Adult (A; 6 month) and Late middle-aged (LMA; 24 month) Fischer 344xBrown Norway rats. Animals were randomly divided into five groups (n=6): non-exercising controls (C), level (L) or eccentric (ECC) (-16°) running at 16m.m-1 and killed immediately post-exercise (0), 48 hours post-exercise (48). Following ECC, vastus intermedius (VI) from A and LMA showed more damage compared to L exercise. Neither age-group had significantly increased VI HSP72 content compared to C. Pooled results founded increased HSP72 content in ECC-48 compared to C (p<0.02). NF-κB activation in the VI was lower in LMA (p<0.001) and unchanged in WG when compared to AC. These findings suggest HSP72 is increased following eccentric exercise in the VI.
713

Left Atrial Phasic Function during Exercise: The Role of Atrioventricular Coupling

Wright, Stephen 11 December 2013 (has links)
Left ventricular (LV) filling increases during exercise, but left atrial (LA) phasic function and its contribution to LV filling is poorly understood. Sixteen endurance-trained middle-aged males were studied at rest and during light (LE) and moderate (ME) intensity cycle-ergometry. Atrioventricular-plane displacement (AVPD) increased from rest to LE (from 14±2 mm to 18±2 mm, p<0.01), but did not increase further at ME. LA reservoir volume increased from rest to LE (from 32±8 mL to 40±10 mL, p<0.01). LA passive contribution increased at LE (from 21±5 mL to 27±8 mL, p<0.01), while LA active contribution increased from rest only at ME (from 12±5 mL to 23±9 mL, p<0.01). AVPD, and thus the longitudinal shortening of LV systole, contributes to LA filling primarily during LE, but is a limited mechanism beyond LE. These data suggest that LV filling appears to shift to a reliance on conduit function to increase LV filling at ME.
714

Characterization of industrial flocculants through intrinsic viscosity measurements

Esau, Arinaitwe 11 1900 (has links)
The effect of pH, temperature, and ionic strength on the molecular conformation of five industrial polyacrylamide-based flocculants was investigated by determining intrinsic viscosities on dilute flocculant solutions. The Fedors equation was found to be most suitable for all flocculants for determining the intrinsic viscosity. The results indicated that the flocculants are fully extended in distilled water at natural pH and at 25°C as evidenced by the high intrinsic viscosities. The data pointed to the strong dependence of the intrinsic viscosity on the presence of salts as a result of the shielding of negatively charged carboxylate groups by the counterions. At a constant ionic strength of 0.01M NaCl, the flocculants assumed a coiled conformation, and further coiling was observed in the presence of small quantities of calcium chloride. CaC1₂ (0.001 mo1/L) There was a decrease in intrinsic viscosities at high pH (~8.5 and 10.5) that was merely attributed to an increase in ionic strength with the increase in concentration of Na⁺ at high pH. Intrinsic viscosity measurements at higher temperatures (35°C and 50°C) showed a small effect of temperature on the conformation of the flocculants. Higher temperature, however, seemed to accelerate the aging of the flocculant solutions. The degrees of anionicity of the flocculants were found to be in the range 1.5% to 50%, as determined through chemical analysis. It was established that determination of total organic carbon content and sodium assays is an accurate way of obtaining the degrees of anionicity of industrial flocculants. The solution stability of the flocculants in distilled water and in 0.01M NaCl was investigated over a period of three days. The reduced viscosities of the anionic flocculant in distilled water steadily decreased. The decrease was more dramatic at high temperature (50°C) than at room temperature, but no viscosity loss was observed in the presence of NaCl. The viscosity of the nonionic flocculant was stable in both distilled water and NaCl. The viscosity loss with time in the case of the anionic flocculant can be correlated with the hydrolysis of the weakly acidic carboxylate (C00⁻) groups to release OH⁻ ions and simultaneous association into uncharged carboxylic (C00H) groups that promote coiling of polyacrylamide. This effect is therefore very similar to the earlier-mentioned effect of sodium chloride.
715

The role of glutathione depletion in skeletal muscle apoptotic signalling in young and old rats

Lalonde, Crystal January 2010 (has links)
There is substantial evidence that oxidative stress causes negative outcomes in many cell and tissue types. This is especially true of skeletal muscle, as it is continually subjected to various sources of reactive oxygen species (ROS). Oxidative stress in muscle has been linked to several disease states as well as to the normal aging process. Oxidative stress has also been associated with increased apoptotic signalling. Furthermore, elevated apoptosis is consistently observed in aged skeletal muscle and is thought to be one of the mechanisms of age-related muscle atrophy. Due to its post-mitotic nature, skeletal muscle may be more susceptible to the harmful effects of oxidative stress in light of its limited regenerative capacity. As a protective measure, a sophisticated antioxidant system exists in muscle consisting of both enzymatic (superoxide dismutases (SOD’s), catalase, glutathione peroxidase) and non-enzymatic elements (glutathione: GSH). GSH is a ubiquitously expressed tripeptide essential to maintenance of the redox status of the cell. Its role in skeletal muscle apoptosis, especially in different muscle types, is currently unclear. To elucidate the potential role of GSH in skeletal muscle apoptosis and oxidative stress, L-buthionine-[S,R]-sulfoximine (BSO) was used to deplete GSH in young (34.85 ± 0.68 wks) and old (69.11 ± 3.61 wks) male Sprague-Dawley rats. Thiol levels (GSH, GSSG), ROS production, 4-hydroxy-2-nonenal (4HNE) levels, DNA fragmentation and apoptosis-related protein expression were examined in soleus (SOL) and white gastrocnemius (WG) muscle. BSO led to significant GSH depletion (89% in SOL, 96% in WG) compared to age-matched controls. Catalase upregulation, in the absence of change in SOD levels, was evident as a result of BSO treatment and advancing age in both muscle tissues. BSO treatment also resulted in increased DNA fragmentation in WG and SOL, with elevated ROS production in SOL only; both of these effects were independent of age. Advancing age resulted in elevated caspase activity and Hsp70 protein content, with a concomitant decrease in anti-apoptotic ARC in SOL but not WG. Additionally, ROS production, 4HNE content, DNA fragmentation and ARC levels were all significantly elevated in SOL compared to WG. These data indicate that SOL may be subjected to a state of elevated cellular stress. There is also some evidence that GSH depletion increases DNA fragmentation while age contributes to a degradative loss of glycolytic muscle.
716

Linking Social Support and Sexual Interest among Older Adults in Intimate Romantic Relationships

Griffith, Jennifer Leigh 21 August 2008 (has links)
This study examines social support and sexual interest among coupled persons aged 57 to 85 in North America. Using quantitative data from the 2006 National, Social Life, Health, and Aging Project (n = 3,005), the dependent variable is sexual interest and the independent variable is social support received from an intimate partner. Using survey and quantitative interview data, I analyze social support older couples receive from their partner, sexual interest, health status, marital status, and gender. In my analysis, I predict that higher levels of social support will positively affect levels of sexual interest, with health, relationship status, and gender mediating the outcomes. This study has gerontological significance because sexuality can impact overall well-being among older adults, and my findings could further our understanding of sexuality among this population.
717

Investigating Memory for Spatial and Temporal Relations with Eye Movement Monitoring

Rondina II, Renante 26 November 2012 (has links)
By using eye movement monitoring (EMM) techniques, investigators have been able to examine the processes that support relational memory as they occur online. However, EMM studies have only focused on memory for spatial relations, producing a lack of EMM evidence for temporal relations. Thus, in the present study, participants performed a recognition memory task with stimuli that varied in their spatial and temporal relations. They were presented with a sequence of objects in a unique spatial configuration, and were instructed to either detect changes in the spatial or temporal relations between study and test presentations. The results provide novel EMM evidence for an interaction between spatial and temporal memory, and the obligatory effects of relational memory processes on eye movement behaviours. Moreover, the current study was also able to test predictions from the temporal context model (Howard & Kahana, 2002), and found evidence for a temporal contiguity effect.
718

Investigating Memory for Spatial and Temporal Relations with Eye Movement Monitoring

Rondina II, Renante 26 November 2012 (has links)
By using eye movement monitoring (EMM) techniques, investigators have been able to examine the processes that support relational memory as they occur online. However, EMM studies have only focused on memory for spatial relations, producing a lack of EMM evidence for temporal relations. Thus, in the present study, participants performed a recognition memory task with stimuli that varied in their spatial and temporal relations. They were presented with a sequence of objects in a unique spatial configuration, and were instructed to either detect changes in the spatial or temporal relations between study and test presentations. The results provide novel EMM evidence for an interaction between spatial and temporal memory, and the obligatory effects of relational memory processes on eye movement behaviours. Moreover, the current study was also able to test predictions from the temporal context model (Howard & Kahana, 2002), and found evidence for a temporal contiguity effect.
719

Images of aging--Baby Boomer style

Rock, Marilyn Osborne 15 June 2013 (has links)
<p> The purpose of this study was to determine the images of aging of a small sample of Early Baby Boomers born between 1946 and 1951. The Baby Boomers are a generation consisting of those born between 1946 and 1964. This study focuses on a narrower range of birth years in order to capture the images of aging of those now 60 and over who came of age in the 1960s and early 1970s. They represent the first wave of the Baby Boom Generation to reach age 65, society's marker of "old age." Baby Boomers are the largest generation in history and currently 10,000 of them are turning 65 every day. The questions posed in this study were to explore how these Early Baby Boomers expect to age, how their generational experience influences their image of aging, and how that image differs from that of previous generations. </p><p> Using a phenomenological and hermeneutical research method, eight men and eight women with like ethnic, demographic, and socioeconomic characteristics were interviewed. Through recordings and verbatim transcriptions the collective meaning of life, aging influences, fears, and expected life spans were determined. The collective results were compared to literature of aging stereotypes of previous generations. This select group reported that they will not age and are surprised when experiencing small signs of aging. Work is what brings meaning to their lives and they have no plans of retiring. They expect to maintain control over the length and quality of their lives. These Early Baby Boomers expect to establish a new image of aging. </p><p> As the numbers of Baby Boomers age and lifespan lengthens, unavoidable losses will occur. Researchers predict an increase in depression, addiction, and dementia. The Early Baby Boomer expects their needs to be met and as those losses occur they will increasingly seek mental health professionals to "fix" their emotional responses. It is important for mental health professionals to understand the unique generational lens from which Boomers view aging in order to provide quality assessment, recommendations, referral, and treatment. </p><p> Key words: boomer; aging; generation; image; mental health; retirement; lifespan.</p>
720

A mindfulness focused grief support group for older adult widows| A grant proposal

Lange, Shiori Koga 09 August 2013 (has links)
<p> As people's life-expectancy prolongs with advanced medical treatments, numbers of individuals who experience widowhood in later life are expected to increase. As a result, grief work will be one of the common challenges that social workers and older adults will face. The purpose of this project was to develop a grant proposal for the Pathways Volunteer Hospice in Lakewood, California, and to identify funding sources for designing a mindfulness focused bereavement support group program for older widows who are age 60 years and over. With funding resources provided by the Weingart Foundation, the proposed program aims to educate participants on the principles of mindfulness and how they can integrate mindfulness principles and philosophy into their grieving process to better facilitate their coping with their loss. The proposed program will be based on empirically supported methods, such as, Mindfulness-Based Stress Reduction and Mindfulness-Based Cognitive Therapy. The actual submission, and/or funding, of this grant was not required for successful completion of this thesis.</p>

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