Browsing by Subject "Aging"
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Item A 25-year life course investigation from emerging to middle adulthood of associations of gender characteristics with fitness and health outcomes(2012-08) Juergens, Cheryl; Fischer, Judith L.; Reifman, Alan; Scott, Jean P.To be posted two weeks prior to my 7/19/12 defenseItem Aging effects of environmental factors on rolled erosion control products(Texas A&M University, 2007-04-25) Khanna, SumeeThis thesis presents a study made on erosion control blankets with respect to their aging and longevity. Erosion control blankets have been relied upon increasingly in recent times replacing the old and traditional methods for protecting areas from erosion by storm water and other factors. But what can be an estimated duration for which a given set of blankets can be functional in channel erosion control. This research is done with the ultimate aim of understanding whether these erosion control blankets can stay in place and be conducive to some vegetation growth, which is said to be the most reliable measure for long-lasting erosion control. Seven erosion control blankets, consisting of natural, synthetic and composite types, were put to actual use for erosion control for 3 years in a field. After 3 years these used materials were cut from the field for conducting the tests. Unused blankets of the same brands were obtained. Index tests were conducted on both used and unused material specimens to measure the erosion control properties. All materials experienced a significant amount of strength loss after use. The natural materials show 80% strength loss, while the composite and synthetic materials were tested to have around 50% strength losses after being put to use for 3 years. Thus it can be observed that the composite and synthetic materials have a decent amount of life where erosion control is concerned. Other tests also proved that composite materials can be relied upon for erosion control to a reasonable extent, and the research goal was achieved.Item Aging, habitual exercise, and vascular ischemia-reperfusion injury(2009-12) DeVan, Allison Elizabeth; Tanaka, Hirofumi, Ph. D.Ischemia-reperfusion (IR) injury occurs during myocardial infarction and during some cardiovascular surgeries. Animal studies support the role of endurance exercise training in preventing myocardial IR injury and coronary endothelial dysfunction. In human and animal studies, habitual exercise has been shown to attenuate endothelial dysfunction caused by aging and disease. It is unknown; however, if exercise can protect against vascular IR injury in humans and if so, whether these effects persist with advancing age. Using 20 minutes of forearm ischemia and the response of the brachial artery as a noninvasive surrogate model for the heart, the association between the mode of exercise training (endurance versus resistance) and vascular IR injury was examined in young healthy adults in the first study. Endothelial function, as measured by flow-mediated dilation (FMD) in the brachial artery, decreased significantly after forearm ischemia, suggesting that this noninvasive model of the heart produces significant and measureable vascular injury. These measures returned to baseline levels within 30 minutes following ischemia, illustrating the transient nature of this form of IR injury. The magnitude of injury and recovery from ischemia were not significantly different among young sedentary, endurance-trained, and resistance-trained subjects, suggesting that exercise training is not associated with protection from vascular IR injury in a young, healthy population. In the second study, the association between aging, endurance exercise training, and vascular IR injury was studied. Twenty minutes of forearm ischemia was associated with a transient fall in brachial FMD in young and older sedentary and endurance-trained subjects. Young subjects recovered more quickly from IR injury than older subjects. Within 30 minutes of injury, the endothelial function of the young group was back to baseline while blunted endothelial function persisted in older subjects for greater than 45 minutes after injury. There was no association between endurance exercise training and enhanced recovery from IR injury. These findings suggest that aging is associated with delayed recovery from vascular IR injury and that endurance training does not appear to modulate the vascular IR injury responses.Item Associations between sleep and memory in aging(2016-05) Sherman, Stephanie Michelle; Schnyer, David M.; Beevers, Christopher G; Haley, Andreana P; Westerberg, Carmen EThe goal of this dissertation was to understand how changes in sleep influence memory performance in healthy older adults. Previous research suggests that older individuals experience parallel declines in sleep and episodic memory. These age-related changes appear to be linked such that sleep disruptions contribute to deficits in memory performance. We examined the components of episodic memory that changed following sleep loss and correlated with aspects of sleep physiology. Healthy older adults completed two overnight sessions: an in-lab sleep recording session and a 24-hour sleep deprivation session. The morning after each sleep manipulation, participants completed both episodic memory and sustained attention tasks. We applied computational models, specifically drift-diffusion models, to the episodic memory tasks to examine whether sleep loss affected memory indirectly through lapses in sustained attention (vigilance hypothesis) or specifically through declines in the strategic processes associated with memory (neuropsychological hypothesis). Our results showed that memory functions that depend on processes associated with the prefrontal cortex were impaired following sleep deprivation. In addition, sleep loss caused a small but robust impairment in sustained attention. Since multiple cognitive processes were impaired by sleep loss in older adults, these findings do not provide unequivocal support for either the neuropsychological hypothesis or the vigilance hypothesis. In addition, we explored which aspects of sleep physiology (recorded during the sleep session) optimized components of memory performance. Our results illustrated that more slow wave power during sleep was correlated with higher next-day source memory strength. Additionally, individuals who spent more time in slow wave sleep had better memory retention. These results support further efforts to investigate sleep as a general indicator of cognitive function across the lifespan and highlight the importance of reinforcing healthy sleep behaviors as a method to preserve cognitive functioning in older adults.Item The balance of souls : self-making and mental wellness in the lives of ageing black women in Brazil(2010-05) Henery, Celeste Sian; Vargas, João Helion Costa; Gordon, Edmund T.; Ali, Kamran; Visweswaran, Kamala; Cvetkovich, AnnThe dissertation explores new understandings about the uses of emotional work in the social struggles of racialized people. This project is a case study that analyzes how a singing group of ageing black women organized to improve the mental wellness of women in a low-income, peripheral neighborhood of the city of Belo Horizonte. This grassroots effort was a response to the women’s use of anti-anxiety medication, specifically Valium, and an attempt to attend to the women’s ongoing issues not addressed through the use of pharmaceuticals. The dissertation examines these women’s self-making as a critical window into how the embodied experiences of the interlocking forces of race, class, gender, age and place of residence are lived in the demanding material and psychological conditions of these women’s lives and the nature of the group’s healing work in their life narratives. Through considering these women’s self-making in discourses of madness, geographic landscapes of memory, musicality and performance, the dissertation investigates how the psycho-emotional transformations of these women illuminate the types of therapeutic work beneficial to anti-racist, sexist and age diversified modes of being and collective mobilization in the current social context of Brazil’s re-democratization. It also considers the group’s re-conceptualization of blackness and mental wellness as exemplary of and contributing to the personal and social work of black women’s struggle and praxis. The research methodology includes participant observation, interviews (structured and un-structured), oral histories, documentary photography and archival research conducted during an extended period (sixteen months) of fieldwork in Brazil.Item Body image, self-concept, and the aging process(Texas Tech University, 1995-08) Eade, Ronda LynA review of the physical attractiveness and aging literature suggested that double standards exist with respect to both age and gender. Physical attractiveness and physical attractiveness with respect to age have each been implicated in the literature as cause for differential treatment in both young and old alike. Implicit in the literature is the notion that physical characteristics attributed to aging (e.g., balding, wrinkling) are judged harshly by today's standards. This is found to be especially true for women and suggested to their affect self-concepts. The present study investigated the relationship between body image and self-concept in the aging process. Results from this study revealed that body image and self-concept were related but did not, as predicted, decrease as age increased. Further, physical and mental symptoms of aging were also related to self-concept but did not increase, as predicted, as individuals aged. Surprisingly, discrepancy between current body image and a retrospective account of body image at age twenty-one was not related to either selfconcept or age. Similar results were found with respect to discrepancy between real and ideal weight.Item Brain control of reproductive aging : GnRH neuroterminal, glia and portal capillary interactions(2008-12) Yin, Weiling; Gore, Andrea C., 1964-Reproductive function is essential to the survival of all species. In mammals and other vertebrates, the control of reproduction relies on the hypothalamic-pituitary-gonadal axis, with the primary driving force provided by hypothalamic GnRH neurons. In the median eminence, the decapeptide GnRH are released in a unique pattern from GnRH neuroterminals into the portal capillary system as part of reproductive cycle. During aging, the biological rhythms of GnRH release are altered in a species-specific manner, with a reduction of GnRH pulsatility and surge in aging female rats resulting in reproductive senescence, which happens much earlier than gonadal failure in rats. Relatively few studies have focused on regulation of GnRH release at the neuroterminal level in the median eminence during reproductive aging. Therefore, the aims of this dissertation are to 1) Study the regulation of GnRH secretion at the neuroterminal level, focusing on glutamate transmission; 2) Ascertain the interaction between GnRH neuroterminals and their surrounding microenvironment focused on glial cells and the portal capillary system in the median eminence; and 3) Analyze age and hormone effects on GnRH neuroterminals and their microenvironment. An aging ovariectomized female rat model was used to study the effects of age and hormones on GnRH neuroterminal system. Fluorescence microscopy, confocal microscopy and transmission electron microscopy were used in conjunction with several imaging analysis tools. I mastered the use of cryo-embedding multi-probe immunogold labeling electron microscopy, which was essential to visualize and quantify the ultrastructral changes in GnRH neuroterminals. I combined the serial electron microscopy with cryo-embedding immunogold electron microscopy preparation and developed a new technique to examine biological markers with a three-dimensional perspective at the cellular level. Results from a series of four research projects showed: 1) There is a novel glutermatergic pathway in GnRH neuroterminals, which may regulate GnRH secretion; 2) There are dramatic age related morphological changes in the GnRH neuroterminal /glia/ portal capillary system of the median eminence that may be involved in reproductive senescence and other neuroendocrine system impairments with age; 3) Serial electron microscopy combined with immunogold labeling technique is a useful method to study the regulation of neuronal signaling pathway. Although my studies were performed on a rat model, it seems reasonable to predict that some of these changes in the median eminence with age may apply to other species, including humans, relevant to some of the menopausal symptoms in women.Item Cbl-b: its role of expression and regulation in T-lymphocyte activation and ageing(2007) Xu, Zhun, 1973-; Jolly, Christopher A.The aging process is strongly associated with decreased activity in the immune system. Dysregulation of T-lymphocyte function, such as reduced proliferation, is one problem faced by most elder people, which prevents them from successfully dealing with exogenous pathogens. Effective regulation of T-lymphocyte activity depends on the proper and prompt transduction of both positive and negative signals within Tlymphocytes and reflects the balance between positive and negative effects. Decline of positive signaling in aging has been studied and reported, while mechanisms concerning up-regulation of negative signaling with age and its role in immune senescence are still unclear. Cbl-b, an E3 ubiquitin ligase, was studied by our lab since it regulates the ubiquitin process, a protein modification process that has suppressive effects on signaling pathways. We first determined the reaction of Cbl-b to different stimuli in young rat splenic T-lymphocytes, and showed that there is a decrease in Cbl-b protein expression upon CD28 stimulation and such protein degradation is proteasome-dependent only. We also showed the mechanism of Cbl-b expression regulation involves the intracellular movement of Nedd4 toward Cbl-b and an up-regulation of Nedd4 expression. Then we proved that in old splenic T-lymphocytes, decreased proteasome activity was unable to down-regulate the Cbl-b protein. High levels of Cbl-b in old T-lymphocytes are functional in preventing PI3K activity and are associated with reduced T-lymphocyte proliferation upon regular stimulation. T-lymphocytes from old Cbl-b knock-out mice show similar proliferative reaction to CD3 stimulation as T-lymphocytes from young wild-type, which establishes the causeeffect relationship between sustained Cbl-b expression and decreased T-lymphocyte proliferation. In summary, these data suggest a unique role of Cbl-b in regulating Tlymphocyte signal transduction and provide critical preliminary data for extending Cbl-b studies into other fields, such as carcinogenesis.Item Characterizing the age-related decline of memory monitoring : neuroimaging and genetic approaches(2011-05) Pacheco, Jennifer Lynn; Schnyer, David M.; Maddox, W T.; Beevers, Christopher G.; Haley, Andreana; Holahan, CaroleMemory monitoring, or the ability to accurately assess one’s memory retrieval success, is known to be declined for older adults. The behavioral decline has been well explored, and is specific to tasks of source monitoring; tasks involving item memory monitoring do not show age-related deficits. This study attempts to further characterize the decline by exploring neuroanatomical contributions to the decline, and genetic influences that may explain performance variability in older adults. Older adults were genotyped for the serotonin transporter (5-HTTLPR) gene, and those that are carriers of the low-expressing allele demonstrate the expected age-related decline of source monitoring performance when compared to younger adults. Interestingly, older adults who lack this allele did not display any decline in performance when compared to younger adults. Neuroanatomical correlates of task performance indicate that prefrontal regions in the inferior and lateral cortices support accurate source memory monitoring, likely through their role in the proper selection of memory cues and inhibition of irrelevant information. This relationship suggests that age-related atrophy occurring in these structures could be responsible for the performance deficits on source memory monitoring tasks. There was no direct relationship seen between genotype for the 5-HTTLPR gene and cortical volumes, however diffusion tensor imaging shows that older adults who carry this allele have altered connections between the medial temporal lobe, responsible for memory retrieval, and prefrontal cortex, which monitors the retrieval process. Through stronger connections of critical networks, older adults who lack the 5-HTTLPR short allele may be able to compensate for the age-related atrophy seen in the prefrontal cortex. Functional results further indicate that the older adult non-carriers recruit inferior and lateral frontal regions to a greater extent than the older adult carriers during accurate memory monitoring. These results begin to suggest a neuroprotective mechanism for the 5-HTTLPR genotype, wherein some older adults may be able to postpone the expected decline of memory monitoring by retaining the ability to recruit essential inferior frontal structures through more organized white matter pathways.Item A co-translational ubiquitination pathway for quality control of newly synthesized proteins(2014-08) Wang, Feng, Ph. D.; Huibregtse, Jon M.; Dudley, Jaquelin; Johnson, Arlen; Paull, Tanya; Russell , RickPrevious studies indicated that 6%-30% of newly synthesized proteins are rapidly degraded by the ubiquitin-proteasome system. This has generally been assumed to occur post-translationally, following failure of chaperone-assisted folding mechanisms. However, the extent and significance of co-translational quality control remains largely unknown. In investigations of ISG15, an interferon-induced ubiquitin-like protein, our lab found that ISG15 is conjugated to a very broad spectrum of newly synthesized proteins. The major ligase for ISG15, Herc5, co-fractionated with polysomes, and further studies indicated that the processes of translation and ISGylation were closely coupled. Here, I employ an in vitro run-off translation system and puromycin labeling experiments to demonstrate that nascent polypeptides are ISGylated within active translation complexes, providing direct support for the co-translational mechanism for ISG15 conjugation. Approaches developed for studying co-translational ISGylation were subsequently used to examine co-translational ubiquitination (CTU), which we hypothesized might be important in quality control of newly synthesized proteins. Consistent with this, I found that the pathway for degradation of newly synthesized proteins was initiated while proteins were being translated, with ubiquitination of actively translating nascent polypeptides. CTU is a conserved and robust pathway from yeast to mammals, with 5-6% of total nascent polypeptides being ubiquitinated in S. cerevisiae, and 12-15% in human cells. CTU products contained primarily K48-linked polyubiquitin chains, consistent with a proteasomal targeting function. Although nascent chains previously have been shown to be ubiquitinated within stalled and defective translation complexes (referred to here as CTU [superscript S]), nascent chain ubiquitination also occurred within active translation complexes (CTU [superscript A]). CTU [superscript A] accounted for approximately two-thirds of total CTU (CTU[superscript T]) in human cells and approximately half of CTU[superscript T] in yeast cells. CTU[superscript A] was increased in response to agents that induce protein misfolding, whereas CTU[superscript S] was increased in response to agents that led to translational misreading or stalling. These results indicate that ubiquitination of nascent chains occurs in two contexts and define CTU[superscript A] as a component of a quality control system that marks proteins for destruction before their synthesis is complete. Finally, decreased translation fidelity is thought to lead to the accumulation of misfolded proteins and hasten the aging process. As CTU is a pathway for quality control of newly synthesized proteins, I explored whether CTU plays a protective role during the replicative aging process in budding yeast. Consistent with previous reports using human cells, I found that newly synthesized proteins are a major source of proteasome substrates under non-stressed conditions. Transient proteasome inhibition (using MG132) led to a decrease of yeast replicative life span (RLS), whereas simultaneous treatment with cycloheximide, a translation inhibitor, suppressed this effect. Deletion of Ltn1, the major E3 ligase of the CTU[superscript S] pathway, also shortened the RLS of yeast. Together, these results provide a preliminary set of evidence supporting the hypothesis that the quality of newly synthesized proteins is an important determinant of aging.Item Coactivation in sedentary and active older adults during maximal power and submaximal power tasks : activity-related differences(2010-05) Newstead, Ann Hamilton; Jensen, Jody L.; Abraham, Lawrence D.; Dingwell, Jonathan B.; Korff, Thomas; Shewokis, Patricia A.; Spirduso, Waneen W.As adults age, they lose the ability to produce maximal power and speed of movement. Success in daily living is often dependent upon power and speed. Thus these age-related decrements in performance can reduce physical independence and quality of life. An active lifestyle in older adulthood is associated with more successful aging. The purpose of this research program was to define the link between habitual activity and performance, specifically in regard to activities requiring power and speed. The hypothesis was that active older adults, compared to sedentary older adults, would be characterized by greater power production in maximal- and submaximal-effort tasks. Grouping older adults by activity level, coactivation was associated with activity level. Functional tasks are performed with a range of power requirements. Coactivation was used to distinguish groups in a maximal power task (Study 1) and submaximal power tasks (Study 2). In Study 1, the young adults demonstrated a greater maximal power than the older adults. While maximal power was not different between the older active and sedentary groups, the groups did differ on how they created maximal power. The active older adults produced a greater coactivation in the lower leg muscles compared to the older sedentary adults. In Study 2, the active older adults responded to different speeds during a submaximal power task with greater coactivation in the muscles of the lower leg at slow speeds compared with the sedentary older adults. Both older adults groups increased coactivation in the thigh muscles at high speeds. The sedentary older adults responded to speed with increased coactivation in the lower leg at fast speeds. The active older adults increased proximal thigh coactivation, EMG index, at the fastest speed compared with the sedentary older adults. Both older adult groups showed muscle activation adaptation to the change in task demands. The results of this dissertation increase our understanding about the link between physical activity and performance. Age-related differences in coactivation were observed during both maximal and submaximal tasks. Activity-related differences were observed suggesting the active older adults have a greater capability to adjust muscle activity to meet the challenges of community living.Item Comparison of fatigue analysis approaches for predicting fatigue lives of hot-mix asphalt concrete (HMAC) mixtures(Texas A&M University, 2006-08-16) Walubita, Lubinda F.Hot-mix asphalt concrete (HMAC) mixture fatigue characterization constitutes a fundamental component of HMAC pavement structural design and analysis to ensure adequate field fatigue performance. HMAC is a heterogeneous complex composite material of air, binder, and aggregate that behaves in a non-linear elasto-viscoplastic manner, exhibits anisotropic behavior, ages with time, and heals during traffic loading rest periods and changing environmental conditions. Comprehensive HMAC mixture fatigue analysis approaches that take into account this complex nature of HMAC are thus needed to ensure adequate field fatigue performance. In this study, four fatigue analysis approaches; the mechanistic empirical (ME), the calibrated mechanistic with (CMSE) and without (CM) surface energy measurements, and the proposed NCHRP 1-37A 2002 Pavement Design Guide (MEPDG) were comparatively evaluated and utilized to characterize the fatigue resistance of two Texas HMAC mixtures in the laboratory, including investigating the effects of binder oxidative aging. Although the results were comparable, the CMSE/CM approaches exhibited greater flexibility and potential to discretely account for most of the fundamental material properties (including fracture, aging, healing, visco-elasticity, and anisotropy) that affect HMAC pavement fatigue performance. Compared to the other approaches, which are mechanistic-empirically based, the CMSE/CM approaches are based on the fundamental concepts of continuum micromechanics and energy theory.Item Creating 'home': a phenomenonological study on place transitions of culturally diverse older women(Texas Tech University, 2003-08) Knotts, Valerie JensenThe purpose of this study was to determine the meaning older women attach to their homes as they experience place transitions or relocation. As these women move to other places of residence, professionals could aid in developing adequate interventions and assistance strategies to more adequately help their clients adapt to these changes. By understanding how these women view "home," how they adapt to change, and how they value people, places, activities and resources, professionals will be able to make an impact on practices aimed at educating students, occupational therapists and other health professionals in more authentic, effective methods of care. Phenomenology is the design concept for this research and follows the work described by Husserl, Van Manen and Merleau-Ponty in terms of documenting the lived experiences of older women. In-depth interviews were conducted with 12 women who had relocated from one place of residence to another. The women, between the ages of 71 and 94, were from varying cultural, ethnic and religious backgroimds. Participant interviews took place with women from Texas, Massachusetts, Maine, Minnesota, Hawaii, France and Egypt. The diversity of participant backgrounds included: Chinese,Irish, Russian/Jewish, Swedish, Egyptian/Islamic, German, African-American, French, Fmish/Norwegian, Hispanic, English and Italian. The interviews were audiotaped and, along with field notes, transcribed and categorized into an N-Vivo qualitative software program. In order to meaningfully understand the phenomenon of place transition, a thematic analysis was undertaken and used as a hermeneutic tool in the tradition of Van Manen.Item Cutaneous and cerebral microvascular response to the ingestion of flavanols in young and older humans : role of nitric oxide(2014-08) Harrison, Michelle Lorraine; Brothers, Robert MatthewThese studies explored interactions between flavanols and nitric oxide in order to investigate implications for vascular health. Study 1 investigated acute effects of flavanol consumption on cutaneous microvascular endothelial function in young and older individuals along with chronic exposure in older individuals. This was accomplished by assessing skin blood flow response to local heating (thermal reactivity, TR); skin was clamped at 34°C and 40°C and values were normalized to those attained at 43°C. Older individuals demonstrated an attenuated TR at baseline during the entire local heating phase (58.4 ± 2.5% versus 49.3 ± 2.6%, p<0.05). Acutely following flavanol ingestion there was a significant increase in TR (52.4 ± 2.1% versus 56.1 ± 2.0%, p=0.05) that was not different with age. There was no effect of chronic flavanol exposure on TR in older individuals; however, there was a significant decrease in mean arterial pressure (95 ± 3 mmHg versus 91 ± 3 mmHg, p<0.001). These results contribute to research regarding flavanols increasing NO bioavailability; acutely via an improvement in cutaneous microvascular endothelial function and chronically via a reduction in blood pressure. Study 2 investigated the acute effects of flavanol consumption on cerebrovascular endothelial function in young and older individuals along with chronic flavanol exposure in older individuals. This was accomplished by assessing basal cerebral blood flow indices (cerebral vascular conductance index, CVCi) and CBF response to hypercapnia (cerebral vasomotor reactivity; CVMR). At baseline older individuals demonstrated a reduced CVCi (0.85 ± 0.04 cm/s*mmHg versus 0.55 ± 0.04 cm/s*mmHg p=0.001) and CVMR (8.6 ± 0.6 versus 6.9 ± 0.4, p=0.05). An unexpected finding was that flavanol ingestion led to an acute decrease in CVCi (0.71 ± 0.04 cm/s*mmHg versus 0.62 ± 0.04 cm/s*mmHg p<0.05) and CVMR (8.6 ± 0.6 versus 6.1 ± 0.5, p=0.001) that was not different with age. In older individuals, chronic exposure led to a significant increase in CVCi (0.60 ± 0.05 cm/s*mmHg versus 0.72 ± 0.06 cm/s*mmHg, p<0.05) but had no effect on CVMR. These data provide evidence for an improvement in cerebral hemodynamics following chronic exposure in older individuals.Item Diabetes, diabetes complications, and their consequences in Mexican-American elders(2007-06-22) Max Elias Otiniano; Kyriakos S. Markides, Ph.D.; Kenneth Ottenbacher, Ph.D.; Jose Loera, MD; Carlos Moreno, MD; Billy U. Philips, Ph.D.The purpose of this study is to describe the epidemiology of diabetes, diabetes complications and their consequences over an 11-year period in Mexican-American elders. Design: This is an 11-year prospective cohort study (1993-1994 to 2004-2005). Setting: This study was conducted among residents of five southwestern states: Texas, New Mexico, Colorado, Arizona, and California. Participants: This is a population-based sample of 3050 non-institutionalized Mexican American men and women aged 65 or older from the Hispanic Established Population for Epidemiologic Studies of the Elderly (H EPESE). Measures: A number of measures were developed that include socio demographic indicators; categories of health behaviors; and self-reports of diabetes, diabetes complications, functional disability, medical conditions, health service utilization, and depressive symptoms. Self-reported heart attack, self-reported stroke, mortality, and HbA1c measure were used as independent variables over the 11-year period. Results: 1) The estimated prevalence of diabetes was 22%. 2) The estimated prevalence of diabetic complications was 60% (retinopathy: 38%, nephropathy: 14%, peripheral vascular disease: 40%, and amputations: 8%). 3) Self-reported heart attack and self-reported stroke are significantly associated with diabetes at 7-year follow-up. 4) At 7-year follow-up, heart attack accounted for 45% of deaths in diabetics. 5) At 11-year follow-up, glycemic control was associated with low education, duration of disease, and severity of disease. Conclusions: These findings suggest that Mexican American elders with diabetes are at high risk of developing diabetes complications, primarily heart attack, stroke, and premature mortality. It is important to promote educational programs aimed at developing healthy lifestyle changes beginning in early adulthood as a preventive measure to delay the onset of disease in this high risk population.Item Effects of aging and exercise training on structural and vasoconstrictor properties of skeletal muscle arterioles(Texas A&M University, 2004-11-15) Donato, Anthony JohnAging is associated with increases in regional and systemic vascular resistance and arterial blood pressure. One possible mechanism through which these age-associated alterations occur is enhanced vasoconstrictor responsiveness, or alterations in the structural properties of the resistance vasculature. We hypothesized that stiffness and vasoconstriction would be greater in skeletal muscle arterioles from old rats, and that endurance exercise training would ameliorate the associated with aging alterations. METHODS: Young sedentary (YS; 4 months), old sedentary (OS; 24 months), young trained (YT) and old trained (OT) male Fischer 344 rats were used. Training modality was treadmill exercise at 15 m/min up a 15o incline, 5 days/wk for 12wks. Skeletal muscle first-order arterioles were isolated for in vitro experimentation. Intraluminal diameter was measured in response to the cumulative addition of endothelin-1, norepinephrine, KCl, and isoproterenol. Stiffness was measure by examining the arterioles' stress and strain relation to increased luminal pressure in Ca++ free solution. RESULTS: Skeletal muscle arterioles had augmented vasoconstriction to endothelin-1 and norepinephrine. Adrenergic vasodilation was diminished in aged rat arterioles. Stiffness increased with age. Exercise training ameliorated the age-associated changes in stiffness and norepinephrine vasoconstriction. Exercise training did not alter endothelin-1 vasoconstriction or adrenergic vasodilation. CONCLUSIONS: These findings suggest that enhanced vascular sensitivity to vasoconstrictors and increased arteriole stiffness may play a role in the increase in skeletal muscle and systemic vascular resistance and, thus, contribute to the elevated blood pressure which occurs in aging humans. These results also demonstrate some of the cardioprotective effects of exercise training.Item Effects of aging and exercise training on the mechanisms of Angiotensin II-induced vasoconstriction in rat skeletal muscle arterioles(2009-05-15) Park, YoonjungAging is associated with increases in regional and systemic vascular resistance and impaired ability to increase blood flow to active muscles during exercise. Aging enhances vasoconstrictor responsiveness in both humans and animals, and an increase in Angiotensin II-induced vasoconstriction is one possible mechanism for old age-associated increase in muscle vascular resistance. The purpose of this study was to determine 1) whether aging alters Ang II-induced vasoconstriction, 2) whether exercise training attenuates the age-associated alteration in Ang II-mediated vasoconstriction, and 3) the mechanism(s) through which aging and exercise training alter Ang II-induced vasoconstriction in rat skeletal muscle arterioles. Male Fischer 344 rats were assigned to 4 groups: Young sedentary (YS; 4 months), old sedentary (OS; 24 months), young trained (YT) and old trained (OT). Exercise-trained groups performed treadmill exercises for 60 min/day at 15 m/min, on a 15? incline for 5 days/week for 10-12 weeks. First-order (1A) arterioles were isolated from soleus and gastrocnemius muscles for in vitro experimentation. Intraluminal diameter changes were determined in response to the cumulative addition of Ang II (3?10-11 - 3?10-5 M). Ang II dose responses were then determined following the removal of endothelium and treatment with NG-nitro-L-arginine methyl ester (L-NAME, 10-5 M), a nitric oxide synthase (NOS) inhibitor. Ang II-induced vasoconstriction was augmented in the aged skeletal muscle arterioles, both in soleus and gastrocnemius muscles, and age-associated increases in Ang II-induced vasoconstriction were abolished with the removal of endothelium and with L-NAME. Exercise training ameliorated the age-induced increase in Ang II-vasoconstriction, and this alteration was eliminated by the removal of endothelium and with NOS inhibition. These findings suggest that aging enhances Ang II-induced vasoconstrictor responses in the arterioles from both soleus, high oxidative, and white portion of gastrocnemius, low oxidative glycolytic muscles, and this age-associated change occurs through an endothelium-dependent NOS signaling pathway. These results also demonstrated that exercise training can ameliorate the age-associated increase in Ang II vasoconstriction in the arterioles from both high oxidative and low oxidative glycolytic muscles through an endothelium-mediated NOS mechanism.Item Emotionality, memory, and aging: assessing evaluative memory with imaginal story sequences(Texas Tech University, 1983-12) Yoder, Carol YvonneNot availableItem Environment- and listener-oriented speaking style adaptations across the lifespan(2014-08) Gilbert, Rachael Celia; Smiljanic, Rajka, 1967-This dissertation examines how age affects the ability to produce intelligibility- enhancing speaking style adaptations in response to environment-related difficulties (noise-adapted speech) and in response to listeners’ perceptual difficulties (clear speech). Materials consisted of conversational and clear speech sentences produced in quiet and in response to noise by children (11-13 years), young adults (18-29 years), and older adults (60-84 years). Acoustic measures of global, segmental, and voice characteristics were obtained. Young adult listeners participated in word-recognition-in-noise and perceived age tasks. The study also examined relative talker intelligibility as well as the relationship between the acoustic measurements and intelligibility results. Several age-related differences in speaking style adaptation strategies were found. Children increased mean F0 and F1 more than adults in response to noise, and exhibited greater changes to voice quality when producing clear speech (increased HNR, decreased shimmer). Older adults lengthened pause duration more in clear speech compared to younger talkers. Word recognition in noise results revealed no age-related differences in the intelligibility of conversational speech. Noise-adapted and clear speech modifications increased intelligibility for all talker groups. However, the acoustic changes implemented by children when producing noise-adapted and clear speech were less efficient in enhancing intelligibility compared to the young adult talkers. Children were also less intelligible than older adults for speech produced in quiet. Results confirmed that the talkers formed 3 perceptually-distinct age groups. Correlation analyses revealed that relative talker intelligibility was consistent for conversational and clear speech in quiet. However, relative talker intelligibility was found to be more variable with the inclusion of additional speaking style adaptations. 1-3 kHz energy, speaking rate, vowel and pause durations all emerged as significant acoustic-phonetic predictors of intelligibility. This is the first study to investigate how clear speech and noise-adapted speech benefits interact with each other across multiple talker groups. The findings enhance our understanding of intelligibility variation across the lifespan and have implications for a number of applied realms, from audiologic rehabilitation to speech synthesis.Item Establishing a rodent (Fischer 344 rat) model of mild cognitive impairment in aging(2009-05-15) LaSarge, Candi LynnMild Cognitive Impairment is characterized by age-related decline in a variety of cognitive domains, including reference and working memory and olfactory function. Importantly, declining age-related mnemonic abilities is not inevitable; learning and memory deficits emerge in some people by middle-age while others remain largely cognitively-intact even at advanced chronological ages. The goal of this thesis is to establish a Fischer 344 (F344) rat model with some features of human cognitive aging which can then be utilized to undercover the neurobiological underpinnings of age-related cognitive deficits. Young (6 mo), middle-aged (11 mo), and aged (22 mo) F344 rats were behaviorally characterized in a well-established reference memory version of the Morris water maze task. Indeed, age-related impairments did occur across the lifespan. Moreover, the reference memory protocol used here was sufficiently sensitive to detect a difference in individual abilities among aged F344 rats such that approximately half of the rats performed on par with young while the other half performed outside this range, demonstrating impairment. These data mimic individual differences in declarative memory among aged humans. Subsequently, subsets of rats initially characterized on the reference memory version of the water maze were tested on either a spatial working memory water maze task or an olfactory discrimination task. Despite detecting an age-related delay-dependent decline in spatial working memory, this impairment was not correlated with spatial reference memory. In contrast, a strong and significant relationship was observed among aged rats in the odor discrimination task such that aged rats with the worst spatial reference memory were also the most impaired in their ability to discriminate odors for a food reward. Importantly, this subset of cognitively-impaired rats was not impaired on digging media discrimination problems with identical task demands, nor were they anosmic. These data are among the first to demonstrate a cross-domain cognitive deficit in a rodent model of human aging. Together, the current study both confirms the use of the naturalistic F344 rat model for the study of cognitive deficits within the context of aging and provides the most comprehensive cognitive profile of this rat population to date.
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