Browsing by Subject "Stress"
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Item A pilot study to examine the effects of Tai Chi on the stress vulnerability of male college students(2009-05) del Rosario, Caelyn Mari C.; McComb, Jacalyn J. R.; Chyu, Ming; Norman, Reid L.; Tacon, Anna M.The purpose of this study was to examine the efficacy of Tai Chi in decreasing stress vulnerability and coping in male college students. Both subjective (perceived) and objective (physiological) responses to stress were analyzed to determine vulnerability and coping to a psychological stressor. Twenty, male college students were randomly assigned to either the control (CTRL) or intervention (TC) group. The TC group practiced Tai Chi twice a week for 8 weeks with each session having a 10min warm-up, 40min TC exercise and a 10min cool-down. The stressor test simulated a stressful situation and consisted of math problems, anagrams, block designs and an extemporaneous speech. To measure perceived stress vulnerability and coping, the Stress Vulnerability Questionnaire, the Perceived Stress Scale, and Spielberger’s State Anxiety Inventory (SSAI). To measure stress vulnerability and coping objectively, the RMSSD, LF & HF powers, and LF/HF ratio were determined as measures of the heart rate variability (HRV) and serum cortisol concentration was also examined. Coping style was also examined with the use of the Problem-Focused Styles of Coping (PFSOC) questionnaire. Significant differences were found in the RMSSD between groups. Significant group by test interactions were found in the SSAI and the PFSOC-suppressive style. TC was shown to increase HRV, and may also decrease perceived anxiety and reduce the suppressive coping style of students when immersed in a stressful situation. No studies have investigated the effect of TC on stress vulnerability and coping of college students to date.Item Abiotic Stress Effects on Physiological, Agronomic and Molecular Parameters of 1-MCP Treated Cotton Plants(2012-02-14) Da Costa, Vladimir AzevedoAbiotic stresses impact cotton (Gossypium hirsutum L.) affecting physiological, molecular, morphological, and agronomic parameters. One of the main yield components in cotton production is the number of bolls per unit area. However, boll abortion is increased when cotton experiences various stresses during its reproductive development that can consequently reduce lint yield. Prior to abscission, a burst in ethylene is observed which may be assumed to be the signal necessary to initiate abscission of that particular structure. It is desirable to prevent fruit loss that may be induced by the peak in ethylene prior to abscission. One potential option to cope with the loss of cotton reproductive structures is the use of ethylene inhibitors. The overall objective of this research was to establish if 1-MCP would synergize, ameliorate, or overcome the effects of abiotic stresses on physiological, molecular, morphological, and agronomic parameters of cotton plants under abiotic stress conditions in field and greenhouse studies. Field and greenhouse experiments were conducted from 2007 to 2009 as a randomized complete block design with four replications in the field, and as a 2x2 factorial design in a split-block arrangement with five replications in the greenhouse. Field treatments consisted of three rates of 1-MCP (0, 25 and 50 g a.i. ha-1) in combination with a surfactant applied at mid-bloom. One day later, ethephon (synthetic ethylene) was applied as a source of abiotic stress. Greenhouse treatments were two 1-MCP rates (0 and 2.4 g a.i. L-1) during a14-h overnight incubation that were then subjected to two water regimes (control and stressed) as the source of stress. Greenhouse assessments with gas exchange analysis revealed that water deficit stress started to impact plants at a moderate water stress, 5 days after 1-MCP treatment (DAT) and a water potential (?w) of -1.4 MPa. The 1-MCP increased water use efficiency in well-watered plants at 1 DAT. Many of the yield components, plant mapping, and biomass parameters investigated were detrimentally affected by drought. However, drought increased specific leaf weight, chlorophyll content, and harvest index. The 1- MCP improved reproductive node numbers mainly during drought, but did not lead to a better harvest index, since 1-MCP caused high abscission. Ethylene synthesis and molecular investigations in greenhouse conditions showed that at 1, 5, 7, 9, 11, and 13 DAT, ethylene production of stressed plants never exceeded those of control plants. As the ?w became more negative ethylene production rate was reduced among stressed plants independent of 1-MCP treatments. However, at 1 DAT 1-MCP caused a transient climacteric stage (ethylene synthesis increase) in leaves. The two primary genes associated with ethylene synthesis, ACS6 (1-aminocyclopropane-1-carboxylic acid synthase) and ACO2 (1-aminocyclopropane-1-carboxylic acid oxidase) expression generally showed an identical trend that supported the ethylene synthesis data. The 1-MCP did not ameliorate any of the detrimental effects of water stress on gas exchange at the point where it started to impact cotton plants. 1-MCP had little or no positive effect on plant mapping, dry matter partitioning and chlorophyll content. Field investigations revealed that at harvest, fruit set in the upper portion of the canopy was influenced by 1- MCP. This portion of the canopy had a greater number of full size, yet immature bolls, which potentially could have had a positive influence on the lint yield. However, ethephon caused the highest lint yield since ethephon treated plants had more open bolls and total bolls in the lower canopy at harvest.Item Acculturation and psychological distress among first generation Asian Americans : the roles of acculturative stress and social-cultural resources(2013-05) Jung, Sooin; Holahan, Carole K.Most acculturation research has been focused on the direct relationship between acculturation and mental health (Yoon, Langrehr, & Ong, 2011; Salanta & Lauderdaleb, 2003; Koneru, Weisman de Mamania, Flynn, & Betancourt, 2007). However, less is known about the mechanisms for this relationship. Social-cultural resources such as friend and neighbor support may have a beneficial impact on mental health, and acculturative stress such as the level of family conflict and perceived racial discrimination would be expected to be risk factors (Kawachi & Berkman, 2001; Wolff & Agree, 2004; Gong et al., 2003; Kerr-Correa, Igami, Hiroce, & Tucchi, 2007). The present study investigated the mediating roles of acculturative stress and social-psychological resources in the relationship between acculturation and psychological distress among first generation Asian Americans. Data were from 1528 Asian Americans who participated in the National Latino and Asian Americans Study (NLAAS), a nationally representative study of the Asian immigrant population in the U.S. Using structural equation modeling with latent variables, direct and indirect influences on Asian immigrant psychological distress were examined. The findings indicate that higher acculturation was not directly associated with psychological distress for Asian immigrants, but there was an indirect pathway from higher acculturation to poorer mental health through acculturative stress. Asian immigrants with higher levels of acculturation experienced more acculturative stress, which contributed to more psychological distress symptoms. However, this finding was moderated by gender, holding only for women. On the other hand, while a higher level of acculturation was also associated with more perceived social resources, the expected protective effect of these resources was not present. The findings show the complex relationship between acculturation and psychological distress during the acculturative process of Asian immigrants.Item Adult hippocampal neurogenesis modulates fear learning through associative and nonassociative mechanisms(2015-05) Seo, Dong-oh; Drew, Michael R., Ph. D.; Domjan, Michael P.; Jones, Theresa A.; Zemelman, Boris; Colgin, Laura L.Adult hippocampal neurogenesis is believed to support hippocampus-dependent learning and emotional regulation. These putative functions of adult neurogenesis have typically been studied in isolation, and little is known about how they interact to produce adaptive behavior. We used trace fear conditioning as a model system to elucidate mechanisms through which adult hippocampal neurogenesis modulates processing of aversive experience. To achieve a specific ablation of neurogenesis, we generated transgenic mice expressing herpes simplex virus thymidine kinase (HSV-TK) under the dcx gene promoter, which directs expression to neural progenitors and immature neurons. Intracerebralventricular injection of the prodrug ganciclovir (GCV) caused a robust suppression of neurogenesis without suppressing gliogenesis. Neurogenesis ablation via this method (DCX-TK/GCV system) or targeted x-irradiation caused an increase in context conditioning in trace but not delay fear conditioning. The data suggest that this phenotype represents opposing effects of neurogenesis ablation on associative and nonassociative components of fear learning. Arrest of neurogenesis sensitizes mice to nonassociative effects of fear conditioning, as evidenced by increased anxiety-like behavior in the open field after (but not in the absence of) fear conditioning. In addition, arrest of neurogenesis impairs associative trace conditioning, but this impairment can be masked by nonassociative fear. The results suggest that adult neurogenesis modulates emotional learning via two distinct but opposing mechanisms: it supports associative trace conditioning while also buffering against the generalized fear and anxiety caused by fear conditioning.Item An exploration of stress, job satisfaction, individual teacher and school factors among Teach For America teachers(2016-05) Reiser, Jenson Elizabeth; McCarthy, Christopher J.; Rochlen, AaronCurrent research suggests that the attrition rate for novice teachers continues to rise and that chronic stress plays a significant role (Ingersoll, 2001; Klassen & Chiu, 2011). While stress in educational settings is widely acknowledged, specific factors contributing to teacher stress are not well understood (McCarthy, Lambert, O’Donnell, & Melendres, 2009). To address this gap in the literature, data were collected from 51 novice teachers (Teach For America corps members and alumni; mean years’ teaching experience = 2.04) to explore vulnerability to stress, job satisfaction, preventive coping resources, perfectionism, and school context (charter vs. district). Results demonstrated that this sample of teachers reported higher than average demands and stress levels, and lower than average levels of classroom resources. Data also suggested higher levels of preventive coping were related to lower perceptions of classroom demands and lower perfectionism scores. Additionally, higher levels of perfectionism were related to lower perceptions of classroom resources. Participants were classified into groups (Resource, Demand, & Balance) based on scores on perceptions of classroom demands and resources. Membership in the Demand group exceeded average numbers found in previous studies. Preventive coping did not differ significantly between members of the Demand group and non-members of the Demand group, though the Demand group had significantly higher perfectionism and significantly lower job satisfaction scores. Finally, while differences in perceived demands were not significantly different by school context, teachers at charter schools showed significantly higher perceived resources. These findings highlight the need to provide a more complex understanding of factors placing novice teachers at risk for occupational stress and could inform decisions on how best to support them.Item An intrinsic CRF signaling pathway in the optic tectum(2012-08) Zhang, Sherry; Carr, James A.; Strauss, Richard E.; Held, Lewis I.; Gollahon, LaurenCorticotropin-releasing factor (CRF) is a 41 amino acid peptide that is best known as the principle hypophysiotropic hormone regulating the pituitary-adrenal axis during stress. CRF also regulates many stressors and anxiety related behaviors including food intake, and over-expression of CRF is thought to be the main causative agent in anxiety related eating disorders such as anorexia nervosa. Recent data collected in our laboratory using amphibian models indicate that, in addition to affecting appetite, CRF may modulate visual sensory pathways involved in detecting and responding to food. Here we examined the hypothesis that CRF directly modulates sensorimotor processing in the optic tectum of the African clawed frog, Xenopus laevis, the major site for integration of visually guided behavior in the non-mammalian brain. Previous studies in X. laevis using RT-PCR revealed that cells in the optic tectum express mRNA for CRF and the CRF R1 receptor but not the CRF R2 receptor. Furthermore, immunohistochemical studies by our laboratory indicate that CRF producing neurons are located strategically in tectal layers 6-8 to intercept retinal information. While these studies suggest that may be released by neurons in the tectum to act locally on CRF R1 receptors, whether or not CRF is actually released by tectal neurons and the existence of cognate CRF R1 receptors in the tectum has never been shown. In the current work, in vitro CRF-release studies revealed that both basal and depolarization-induced release of CRF, determined using a homologous radioimmunoassay, was greater from the optic tectum relative to the telencephalon, hypothalamus/midbrain or brainstem. These findings most likely reflected regional differences in the inhibitory regulation of CRF, as tectal content of CRF was actually lower than that of the hypothalamus in the two anuran species that have been studied to date. Depolarization-induced release of CRF from the optic tectum was calcium dependent. Radioligand binding studies indicated that specific binding of [125I-Tyr]-oCRF to tectal cell membranes could be displaced by the CRF R1 selective antagonists antalarmin or NBI 27914. CRF enhanced cAMP content in tectal slices in vitro, but the differences were not statistically significant. In order to figure out whether the control of CRF neurons is controlled by chemically defined pathways innervating the tectum we conducted in vitro studies with glutamate, the primary excitatory neurotransmitter in the tectum, neuropeptide Y (NPY) and the cholinergic agonist carbachol. The results showed that glutamate significantly inhibited basal and depolarization-induced CRF release from optic tectum. We conclude that the optic tectum possesses a CRF signaling system that may be involved in modulating communication between sensory and motor pathways involved in food intake.Item Assessing the psychosocial risk factors for coronary artery disease: an investigation of predictive validity for the psychosocial inventory for cardiovascular illness(2009-08) Baker, Maria Kathryn; McCarthy, Christopher J.This dissertation investigated the psychometric properties and clinical applications of the Psychosocial Inventory for Cardiovascular Illness (PICI). The PICI is an inventory developed to measure the psychosocial risk factors for heart disease including anxiety, depression, stress, social isolation, and anger. The inventory was developed to measure the ways that each psychosocial risk factor contributes to the coronary artery disease process through the lifestyle behaviors and pathophysiological mechanisms with which they are associated. The primary purpose of the study was to examine predictive validity for the PICI. With support for predictive validity, the inventory may aid in early identification of individuals at increased risk for coronary artery disease (CAD) so that behavioral, psychosocial, and medical interventions can be implemented. Both healthy and cardiac samples were used in the inventory development and validation process. The PICI was administered in conjunction with similar inventories and physiological markers of CAD were collected including percent of coronary artery blockage and history of heart attacks. Item analysis and factor analysis were used to yield a 20-item PICI comprised of three subscales to include Negative Affect, Social Isolation, and Anger. It was hypothesized that the PICI subscales would predict group membership; whether or not a participant carried a diagnosis of CAD, and would be have a strong relationship to the physiological markers of CAD that were measured. Analysis revealed that the PICI was unable to predict diagnostic status and did not have a strong relationship with the physiological markers of CAD. Results suggest that the PICI has acceptable reliability and construct validity as demonstrated in the current sample, yet further investigation must be conducted to gain support for the instrument’s predictive abilities.Item Beyond balance : examining work-family interface, role negotiation, and coping strategies for female caregivers in STEM(2016-08) Reilly, Erin Dawna; Awad, Germine H.; Rochlen, Aaron B.; Cokley, Kevin O; McCarthy, Christopher J; Walkow, Janet CThough the retention of female caregivers in STEM fields has become increasingly discussed, there is a lack of research investigating the major factors impacting their successful negotiation of work and family responsibilities and roles. This body of research examined the impact of societal roles, external support structures, and coping resources on work-family satisfaction and psychological well-being. In particular, this study investigated the following: (1) the relationships among work support, family support, coping, and satisfaction; (2) the relationship between family- and occupational-support, work-family conflict, and satisfaction; (3) coping resources as a mediator of the relationship between work-family conflict and work and family satisfaction, and; (4) the impact of internalizations of competing societal myths (i.e., the ideal worker myth and motherhood myth) as moderating the impact of work-family conflict on interpersonal guilt. Participants included 204 women in STEM fields who also reported caregiving responsibilities. The majority of the recruited sample identified as mothers, and reported approximately equal amounts of time spent on occupational responsibilities and caretaking work. Results indicate that women who reported higher levels of family support and occupational support tended to have higher levels work and family satisfaction, as well as greater perceived internal coping resources. In addition, women with greater perceived abilities to identify, predict, and plan for demands and possible stressors tended to have greater levels of family and work satisfaction. In terms of modeling work-family interface, women who reported higher levels of familial and career-climate support tended to also report greater perceived coping resources and abilities. However, the hypothesis that work-to-family and family-to-work conflict would significantly predict lower work satisfaction and family satisfaction was not supported when modeled alongside other variables (external support and coping). On the other hand, the hypothesis that the relationship between family-to-work conflict and work satisfaction was mediated by perceived coping resources was supported. Finally, results suggest that greater internalization of the motherhood myth, the ideal worker myth, and the presence of work-to-family conflict are associated with higher levels of guilt for female caregivers in STEM fields. Limitations, future research areas, and practical implications of these findings are discussed.Item Cancer bloggers' styles of humor while coping with cancer(2014-05) Anderson, Allison Gray; Donovan-Kicken, Erin E.This study explores the use of humor among bloggers coping with cancer. Framed by health communication literature on stress and coping and literature on humor styles, I analyzed the use of humor by individuals coping with various types of cancer. Using content analysis, I investigated 600 blog posts from 85 cancer bloggers for humor use. I adapted the Humor Styles Questionnaire (HSQ), a scale assessing four different uses of humor, into a codebook to use for content analysis within the blog posts. The different styles of humor included affiliative, self-enhancing, aggressive, and self-defeating. Individually, I tested the relationships between the style of humor a blogger used and the blogger’s gender, age, type of cancer, and point in the cancer trajectory. I also tested the relationships between the frequency of humor use within each blog post and the blogger’s gender, age, type of cancer, and point in the cancer trajectory. Every humorous remark was categorized into at least one of the four humor style categories. Overall, I found no significant relationships among the variables tested. However, each of the humor styles was used multiple times throughout the sample. This study provides future researchers with a new way to operationalize humor use based on the HSQ and with relevant examples from cancer blogs. The findings also suggest that humor is a common communicative device among those coping with cancer, and further research into how humor is used among more specific samples of cancer patients may provide more significant results.Item Characterization of the stress response of red snapper: connecting individual responses to population dynamics(Texas Tech University, 2008-08) Campbell, Matthew Denis; Diamond, Sandra; Patino, Reynaldo; Strauss, Richard E.In the Gulf of Mexico, red snapper (Lutjanus campechanus) are considered to be the most important species for both commercial and recreational fishing. Red snapper were first classified as an overfished species in 1984 and are still considered as such (Schirripa and Legault 1999). Various studies have shown a high degree of uncertainty with the assumption of post-release survival in the fishery. The intent of this dissertation was to evaluate responses of red snapper to stress in the laboratory and the field, and then model those effects at the population level of organization. Both lab and field data demonstrated that with increasing depth and water temperature, the physiological health of red snapper diminished. This decrease in physiological health resulted in elevated immediate mortality rates due to their inability to cope with elevated stress and increased predation. A triage procedure called BtR score was developed and is a synergistic metric that accounts for external features of barotrauma and loss of reflex response capability. The BtR score showed a significant logistic functional relationship to observed mortality in the field and represents a tool that will allow prediction of immediate mortality. Mean BtR score from field data generated 4 different estimates of release mortality (20%, 30%, 33%, and 39%). These release mortality estimates were used to calculate concomitant increases in fishing mortality for this population, and were then applied in a matrix projection model. Results of the model indicate that release mortality rates 35% and greater generate declining population trends. Application of a slot limit to the fishery or reduction of age 1 red snapper bycatch, were both capable of returning the worst case scenario model back to equilibrium. The overall picture is that release mortality is a significant issue for the red snapper fishery. Continued investigation is recommended as more information about density dependent effects for this population become available. Reductions in total catch, release mortality, and bycatch are recommended to achieve sustainability for this population.Item Computaional modeling of membrane mechanics(Texas Tech University, 2006-08) Kundomal, Chellaram A.; Seshaiyer, Padmanabhan; Martin, Clyde F.; Schovanec, LawrenceIn this work we analyze mechanics of thin membranes. After a brief review on the backgrounds and methods, this thesis develops a systematic approach to understanding membrane mechanics. The two essential mathematical tools employed include Principle of Virtual Work and the finite element method. More specifically after defining suitable measures of deformation of an arbitrary body, we describe how one can apply the Principle of Virtual Work for a fully dynamic application. We employ the finite element method to a quasi-static application which results in a system of nonlinear equations. These equations are solved by the Newton-Raphson procedure for systems. The computational methodology discussed in this work was implemented in Maple for two different membrane materials: neo-Hookean and Mooney-Rivlin.Item Correctional psychologist burnout, job satisfaction, and life satisfaction(Texas Tech University, 2006-12) Senter, Aven; Morgan, Robert D.; Reich, Darcy A.; Hardin, Erin E.; Richards, StevenResearch suggests the correctional work environment is stressful. Since much of the literature has focused on correctional officers, there are only three existing studies that have examined correctional psychologist job satisfaction. These studies suggest correctional psychologists are dissatisfied with various aspects of their jobs, such as administrative responsibilities, limited opportunities for advancement, and lack of influence with decision-making. Much of the literature on correctional psychologists surveyed their work-place activities and assessed job satisfaction with non-standardized measures. Although these seminal studies were instrumental in highlighting areas of concern for correctional psychologists, they did not comprehensively examine these issues with a high degree of empiricism. This study utilized standardized instruments to assess the constructs of burnout, job satisfaction, and life satisfaction of correctional psychologists relative to other public service and counseling center psychologists. Data were collected from 203 doctoral level psychologists working full-time in the following settings: 44 were employed in Criminal Justice (CJ) settings, 56 were employed in Veteran’s Affairs (VA) settings, 49 were employed in Counseling Center (CC) settings, and 54 were employed in Public Psychiatric Hospital (PPH) settings. Preliminary analyses using analysis of variance (ANOVA) and Chi Square procedures were conducted to compare differences in continuous and categorical demographic variables, respectively. The only notable difference in psychologist groups was job tenure, which was entered as a covariate in subsequent analyses. Several multivariate analysis of covariance (MANCOVA) and analysis of covariance (ANCOVA) procedures were utilized for the main analyses. Lastly, a series of simple linear regression (SLR) procedures were utilized to assess for the influence of predictor variables. Overall, each group of psychologists generally reported low to moderate levels of burnout, moderate levels of job satisfaction, and high levels of life satisfaction. However, psychologists working in correctional settings reported significantly more burnout relative to VA and counseling center psychologists. Psychologists working in correctional and public psychiatric hospital settings also reported significantly lower job satisfaction than counseling center psychologists. Additionally, psychologists working in public psychiatric hospital settings reported significantly lower life satisfaction than VA and counseling center psychologists. Lastly, professional identity related to the occupational setting emerged as a significant predictor of the level of psychologist burnout.Item The downside of sexual restraint : sexual frequency, frustration, and stress(2012-05) Wright, Brittany Lauren, 1985-; Loving, Timothy J.; Neff, Lisa A.; Gleason, Marci E.Individuals in passionate love often experience a strong desire to engage in sexual intercourse with their partners. In a previous study (Crockett, Wright, & Loving, under review), individuals who were engaging in less (vs. more) sexual intercourse during the early stages of their romantic relationship were more likely to experience acute elevations in cortisol in response to a passionate love prime. In the present study, I examined whether sexual frustration mediates any association between sexual frequency and cortisol. Subjects underwent the same passionate love prime employed in Crockett et al.’s study, and completed measures of sexual intercourse frequency and feelings of sexual frustration. Salivary cortisol samples were collected before and after the prime. Sexual frequency was significantly correlated with sexual frustration, such that individuals who were engaging in less sex experienced more sexual frustration. However, sexual frequency and sexual frustration both failed to predict cortisol reactivity to the prime. I discuss the possible methodological issues that may account for these null effects and offer suggestions for future studies that examine the physiological consequences of sexual frequency and frustration.Item Effects of Acute and Chronic Stress on Immune- and Inflammatory-response Gene Expression in Beef Calves(2012-02-14) Terrill, CooperTransport stress research has shown correlations among stress, morbidity, and mortality in calves subjected to the traditional U.S. market system, indicating the possibility of compromised immune function. The objective of this study was to determine if expression of specific immune and inflammatory response genes differed between calves that were subjected to either an acute stress (AS, handled and weaned for 1.5 h) or a chronic stress (CS, weaned, handled and transported for 3 to 4 d). Two groups of forty calves, Bos taurus (n = 20) and crossbred calves (n = 20), weighing 181 kg to 250 kg were used in each of two trials. Jugular veni-puncture blood samples (9 ml) were collected from AS calves 1.5 h after the start of handling and separation from their dam. Samples were collected from CS calves during processing after arrival at a north Texas feed lot. RNA for gene expression analysis was extracted from peripheral blood leukocytes obtained from blood samples by a filtration method. During the second trial, the filtrate was centrifuged for measurement of plasma cortisol. A diagonal covariance mixed model ANOVA was used to determine effects of treatment, breed, and breed by treatment interaction on cortisol concentrations. Expression values for each gene were analyzed using linear models that considered the effects of treatment (AS and CS) and breed (Bos taurus and crossbred calves) comparing each trial separately. Mean plasma cortisol concentrations did not differ between AS (16.40 +/- 1.08 ng/ml) and CS calves (18.06 +/- 1.14 ng/ml) (P > 0.296). The interaction of effects was detected for 2 genes in Trial 1, and 3 genes in Trial 2 (P < 0.029). Breed was influential for 5 genes in both Trial 1 and 2 (P < 0.046). Significant differences were found in relative quantification for 30 genes in Trial 1 and 36 genes in Trial 2, in which CS calves had greater expression than AS calves (P < 0.047). Fifteen of those genes were common between the two trials with mean treatment differences of RQ values from the 15 genes ranging from 0.309 to 913.19, excluding outliers. Similar elevated cortisol concentrations in both the AS and CS calves indicated that both groups experienced significant stress. However, changes in gene expression differences were greater in the calves subjected to CS, indicating that gene expression may be more useful than cortisol for identifying detrimental long-term stress.Item The effects of acute and chronic stress on sexual arousal in women(2010-05) Hamilton, Lisa Dawn, 1979-; Meston, Cindy M.; Delville, Yvon; Jones, Theresa A.; Gore, Andrea C.; Dormire, Sharon L.In most adult animals, stress is generally thought to be detrimental to reproductive (sexual) function. However, in humans, there is a limited body of literature that indicates some stress can potentially be beneficial for sexual function. One theory is that there is an inverted U relationship between stress and sexual function with low and high levels of stress (or anxiety) causing an impairment of sexual response, while a moderate level of stress facilitates sexual arousal. This aim of this dissertation is to identify the mechanisms through which both acute and chronic stress may facilitate or impair sexual arousal in women. In particular, I examined the role of adrenal hormones, the autonomic nervous system (ANS), and psychological factors. To test these mechanisms, I measured cortisol, dehydroepiandrosterone sulfate (DHEAS), heart rate, distraction, and misattribution of arousal during stressful and sexual laboratory situations. Two of the studies examined the effects of acute stress, and the final study focused on chronic stress. Results indicated that acute stress is beneficial for genital arousal in women, and that the sympathetic branch of the ANS is the key mechanism involved in that relationship. High levels of chronic stress were found to significantly impair genital arousal compared to average levels of chronic stress. Increased levels of cortisol and distractions contributed to this effect. DHEAS did not appear to play a role in the relationship between stress and sexual arousal, and there was no evidence for misattribution of arousal. Neither acute nor chronic stress affected women’s subjective (psychological) arousal. Acute and chronic stressors affect sexual arousal in different ways and through separate mechanisms. The findings from these studies can inform treatment approaches for women with sexual arousal difficulties.Item Evaluating Usage, Preferences, and Perceived Restorative Qualities of Staff Break Areas in Healthcare Facilities(2015-01-20) Nejati, AdelehNurses are extremely important to the healthcare industry, and maintaining the quality of nursing care is one of the central concerns of today?s healthcare managers. Unfortunately, the nursing profession in the U.S. is on the precipice of a crisis. Healthcare facilities are suffering from high rates of staff burnout and turnover, and interest in the profession among younger students is on the decline. Healthcare leaders are concerned for improving nurses? satisfaction, performance, and job retention, but they often overlook the importance of respite for nurses, and underestimate the value of well-furnished staff break areas. A healthy break area can improve nurses? mood, attitude, and alertness, factors that have been associated with a higher quality of patient care and better facility outcomes. In this study, the researcher gathered empirical evidence regarding nurses? desires and responses to different environmental features of staff break areas. The design interventions that were tested included (a) the proximity of break areas to work areas, (b) levels of socializing vs. privacy, (c) visual and physical access to the outdoors, (d) the presence of artworks, plants, and natural light, and (e) amenities for indoor and outdoor break spaces. These break-room features were examined in regard to their perceived restorative qualities and their potential to affect staff usage and satisfaction. A multi-method approach was used in the research, employing both qualitative explorations (focused interviews and narrative survey questions) and quantitative measurements (discrete survey questions and a visual ranking of break-room spaces). Important findings include the result that staff break areas are more likely to be used if they are in close proximity to nurses? work areas, that these spaces need complete privacy from patients and families, and that it is most effective to provide a mixture of opportunities for individual privacy and socialization with co-workers. Having physical access to private outdoor spaces (e.g., balconies or porches) was shown to have a significantly greater restorative effect in comparison with window views, artwork, or indoor plants. The study outcomes were incorporated into a set of design and policy suggestions to encourage effective improvements in the quality of nurses? rest breaks.Item Evaluation of adrenal function, growth, carcass characteristics, blood metabolites, hematological and immune parameters in Angus, Brahman, Bonsmara X Angus and Bonsmara beef steers(Texas A&M University, 2006-10-30) Jacobs Hollenbeck, ReginaAdrenal function, blood metabolites, hematological parameters, growth, and carcass characteristics were compared in tropically-adapted (Brahman,) intermediate (Bonsmara and Bonsmara X Angus crossbred,) and temperate (Angus; n=10 each) beef steers. An adrenal gland challenge was conducted, entailing serial blood collection at 15-min intervals for a 12.5-h period, with administration of exogenous ACTH (0.1 IU/kg BW) 2.5-h into the experiment. Steers were maintained on Coastal bermudagrass pastures overseeded with ryegrass for five month; body weights and blood samples were obtained every 21 days. An anterior pituitary/adrenal gland challenge was conducted, entailing serial blood collection at 120, 90, 60 and 30 min prior to, and 10, 20, 30, 60 and 120 min following administration of exogenous CRH (0.1 ug/kg BW). Physical and physiological signs of heat stress were assessed, and blood samples were obtained for analysis. Exit velocity was measured. Carcass characteristics were determined post-slaughter. Statistical analysis was conducted using ANOVA for repeated measures, using least square means and Pearson??????s and Spearman??????s correlation analyses. Bonsmara and Bonsmara X Angus had lower basal cortisol (CS) than Angus and Brahman steers. Angus steers had greater adrenal responsiveness to ACTH, and responded faster to CRH than the other breedtypes. Bonsmara steers were slower in responding to CRH, and returning to basal CS following ACTH or CRH administration. Angus and Bonsmara X Angus grew faster during the finishing phase than Brahman or Bonsmara steers. Angus had higher quality grades than other breedtypes; rib-eye area and hot carcass weight were greater in Angus than Brahman steers, but similar among Angus, Bonsmara X Angus and Bonsmara steers. Angus and Brahman were less docile than Bonsmara and Bonsmara X Angus steers. Angus steers had higher respiration rates and serum concentrations of sodium, lower aldosterone during moderate heat exposure, and lesser serum concentrations of glucose, urea and cholesterol than tropically-influenced breedtypes. Angus had rectal and surface temperatures similar to those of Brahman, but greater than those of Bonsmara X Angus or Bonsmara steers. Intermediate breedtypes like the Bonsmara provide a compromise to producers, allowing them to address the demands of consumers while raising cattle better suited to survival in tropical climates.Item Evaluation of the relationship between animal temperament and stress responsiveness to M. longissimus lumborum tenderness in feedlot cattle(Texas A&M University, 2007-04-25) King, David AndrewTemperament effects on meat quality were investigated using three contemporary groups consisting of Bonsmara-sired yearling-fed (n = 31), Angus-sired calf-fed (n = 49), and Angus-sired yearling-fed (n = 48) steers. To evaluate temperament, exit velocity, pen scores, and chute scores were determined before shipment to the feedlot, and exit velocity was measured on arrival to the feedlot and after approximately 70 d on feed. Serum cortisol concentration was determined at each evaluation and before slaughter. At slaughter, pH and temperature were monitored in the M. longissimus lumborum. USDA yield and quality grade factors and CIE color space values were determined, and M. longissimus lumborum steaks were evaluated for sarcomere length, 72-h calpastatin activity, proximate composition, and Warner-Bratzler shear force (WBS) values 3, 7, 14, and 21 d postmortem. Temperament categories were based on rankings within contemporary groups at each evaluation. Temperament traits were consistent across evaluations, and values decreased (P < 0.05) in magnitude over time. Relationships between temperament traits were consistent across contemporary groups. Increasing excitability was associated with higher (P < 0.05) serum cortisol concentration. Body weight was slightly lower (P < 0.05) in cattle with excitable temperaments at all evaluations. Carcass characteristics, proximate composition, muscle color, and calpastatin activity were unaffected by temperament. Carcasses from cattle with calm temperaments had higher 0.5 h postmortem pH values than those from intermediate and excitable cattle (0.1 and 0.2 units, respectively). The Angus-sired yearling-fed steers classified as Excitable had higher (P < 0.05) WBS values than the calmer Angus-sired, yearling-fed steers. This trend was observed in the Bonsmara-sired steers, although the values were not statistically different. No differences attributable to temperament were apparent in the Angus-sired calf-fed steers. Correlations were highest between temperament values and tenderness after 21 d. Yearling-fed cattle classified as Excitable before shipment to the feedlot produced tougher (P < 0.05) steaks than those from calmer animals. At evaluations later in production, Calm steers produced tougher (P < 0.05) steaks. Tenderness did not differ across temperament categories in calf-fed steers regardless of sorting time. These data indicate temperament influences tenderness, though the mechanism is not clear.Item Exploring the links between stress and innate immune responses in cattle(2010-12) Hulbert, Lindsey E.; Ballou, Michael A.; Carroll, Jeffery A.; Randel, Ronald D.; Welsh, Thomas H.; Galyean, Michael L.Cattle morbidity and mortality are observed more frequently during potential stressful situations, such as weaning, transportation, and commingling. The objectives of this dissertation were to identify intrinsic factors, such as sex-classification and temperament and extrinsic factors such as transportation, feeding strategies and weaning that might influence the stress and innate immune responses of cattle. A sexually dimorphic immune response to endotoxin or corticotropin-releasing hormone (CRH) was observed among Brahman heifers and bull calves. Heifers displayed less sickness behaviors but had greater rectal temperature and circulating tumor-necrosis-factor alpha (TNF-α) response to an in vivo endotoxin challenge than bulls. Heifers also had less of a circulating corticoid response than bulls after CRH and had an acute increase in circulating cytokines that was greater than bulls. Brahman bulls classified as temperamental had less neutrophil activity after transportation than bulls classified as calm. Weaning is a potentially stressful event for calves.. Many innate immune responses in Holstein calves including neutrophilia and decreased phagocytic and oxidative burst capacities were suppressed transiently following weaning. Early weaning calves at 24 d of age rather than at 45 d of age also suppressed neutrophil L-selectin expression. Furthermore, early weaning lightweight calves also suppressed the secretion of TNF-α from whole blood cultures stimulated with LPS. Switching Holstein calves from twice daily to once a daily feeding during the 4th week of life was a mild stressor. There was only a tendency for neutrophilia among the once-fed calves. No other aspects of innate immune responses were acutely suppressed by feeding frequency. These studies indicate that the stress effect of stress on immune responses of cattle is complex. Sex classification, age, and temperament of cattle influence how an animal responds to stress and subsequently, how stress will impact the innate immune system. These studies all indicate that stress can cause an initial suppression of the immune system, but in several instances, the innate immune system had compensatory response, where increased activity after stress is observed.