Matching Items (19)
Filtering by
- All Subjects: psychology
- All Subjects: Drug resistance in microorganisms
- Creators: Burleson, Mary
Description
The study of bacterial resistance to antimicrobial peptides (AMPs) is a significant area of interest as these peptides have the potential to be developed into alternative drug therapies to combat microbial pathogens. AMPs represent a class of host-mediated factors that function to prevent microbial infection of their host and serve as a first line of defense. To date, over 1,000 AMPs of various natures have been predicted or experimentally characterized. Their potent bactericidal activities and broad-based target repertoire make them a promising next-generation pharmaceutical therapy to combat bacterial pathogens. It is important to understand the molecular mechanisms, both genetic and physiological, that bacteria employ to circumvent the bactericidal activities of AMPs. These understandings will allow researchers to overcome challenges posed with the development of new drug therapies; as well as identify, at a fundamental level, how bacteria are able to adapt and survive within varied host environments. Here, results are presented from the first reported large scale, systematic screen in which the Keio collection of ~4,000 Escherichia coli deletion mutants were challenged against physiologically significant AMPs to identify genes required for resistance. Less than 3% of the total number of genes on the E. coli chromosome was determined to contribute to bacterial resistance to at least one AMP analyzed in the screen. Further, the screen implicated a single cellular component (enterobacterial common antigen, ECA) and a single transporter system (twin-arginine transporter, Tat) as being required for resistance to each AMP class. Using antimicrobial resistance as a tool to identify novel genetic mechanisms, subsequent analyses were able to identify a two-component system, CpxR/CpxA, as a global regulator in bacterial resistance to AMPs. Multiple previously characterized CpxR/A members, as well as members found in this study, were identified in the screen. Notably, CpxR/A was found to transcriptionally regulate the gene cluster responsible for the biosynthesis of the ECA. Thus, a novel genetic mechanism was uncovered that directly correlates with a physiologically significant cellular component that appears to globally contribute to bacterial resistance to AMPs.
ContributorsWeatherspoon-Griffin, Natasha (Author) / Shi, Yixin (Thesis advisor) / Clark-Curtiss, Josephine (Committee member) / Misra, Rajeev (Committee member) / Nickerson, Cheryl (Committee member) / Stout, Valerie (Committee member) / Arizona State University (Publisher)
Created2013
Description
Approximately one-third of Iraq and Afghanistan veterans develop mental health problems, yet only 35-40% of those with mental disorders are seeking mental healthcare (Hoge, et al., 2004; Vogt, 2011). Military spouses may be an important resource for facilitating treatment seeking (Warner, et al., 2008), especially if service member mental health issues are impacting the marriage. Military spouses might be hesitant to encourage service member help-seeking, however, due to perceived threat of adverse military career consequences. For this study, 62 military wives completed an online survey. As part of the survey, participants were randomly assigned to one of four vignettes containing a description of a hypothetical military husband with mental health symptoms. Each vignette presented different combinations of marital conflict (high versus low) and service member concerns about adverse career consequences (high versus low). Wives rated on a five-point scale how likely they were to encourage the hypothetical military husband to seek help. It was hypothesized that spouses would be more willing to encourage help-seeking when concerns about adverse military career consequences were low and marital distress was high. No main effects or interaction effect were found for marriage and career. Perceived stigma about seeking mental health treatment in the military, psychological identification as a military spouse, and experience and familiarity with military mental healthcare policies failed to moderate the relationship between marital conflict, career concerns, and encouragement of help-seeking. Correlational analyses revealed that (1) greater experience with military mental healthcare (first- or secondhand), and (2) greater perceptions of stigma regarding seeking mental healthcare in the military each were associated with decreased perceptions of military supportiveness of mental healthcare. Therefore, although the experimental manipulation in this study did not lead to differences in military spouses' encouragement of a hypothetical military service member to seek mental health services, other findings based on participants' actual experiences suggest that experiences with military mental healthcare may generate or reinforce negative perceptions of military mental healthcare. Altering actual experiences with military mental healthcare, in addition to perceptions of stigma, may be a useful area of intervention for military service members and spouses.
ContributorsHermosillo, Lori (Author) / Roberts, Nicole (Thesis advisor) / Burleson, Mary (Committee member) / Tinsley, Barbara (Committee member) / Arizona State University (Publisher)
Created2013
Description
Researchers have found inconsistent effects (negative or positive) of social relationships on self-control capacity. The variation of findings may depend on the aspects of social relationships. In this study, rather than examining overall social relationships and self-control, characteristics in social relationships were clearly defined, including social support, social connection and social conflict, to determine their specific effects on self-control. An online survey study was conducted, and 292 college students filled out the survey. For data analysis, path analysis was utilized to examined the direct effect and indirect effect from social relationships to self-control. Results showed social connection and social conflict may indirectly associate with self-control through stress, but social support does not. It may suggest, in traditional stress buffering model, it is the social connection in social support that really reduce the stress. Concerning the direct effects, social support and social connection were significantly associated with self-control directly, but social conflict does not. This result may support the Social Baseline Theory that positive social relationships have direct regulating effects. Results are good for guidance of experimental manipulation of social relationships in study of social influences of self-control.
ContributorsGuan, Xin (Author) / Burleson, Mary (Thesis advisor) / Roberts, Nicole (Committee member) / Schweitzer, Nicholas (Committee member) / Arizona State University (Publisher)
Created2012
Description
Intrinsic antibiotic resistance is of growing concern in modern medical treatment. The primary action of multidrug resistant strains is through over-expression of active transporters which recognize a broad range of antibiotics. In Escherichia coli, the TolC-AcrAB complex has become a model system to understand antibiotic efflux. While the structures of these three proteins (and many of their homologs) are known, the exact mechanisms of interaction are still poorly understood. By mutational analysis of the TolC turn 1 residues, a drug hypersensitive mutant has been identified which is defective in functional interactions with AcrA and AcrB. Antibiotic resistant revertants carry alterations in both TolC and AcrA act by stabilizing functional complex assembly and opening of the TolC aperture, as monitored by stability of a labile TolC mutant and sensitivity to vancomycin, respectively. Alterations in the AcrB periplasmic hairpin loops lead to a similar antibiotic hypersensitivity phenotype and destabilized complex assembly. Likewise, alterations in TolC which constitutively open the aperture suppress this antibiotic sensitivity. Suppressor alterations in AcrA and AcrB partially restore antibiotic resistance by mediating stability of the complex. The AcrA suppressor alterations isolated in these studies map to the three crystallized domains and it is concluded they alter the AcrA conformation such that it is permanently fixed in an active state, which wild type only transiently goes through when activated by AcrB. Through this genetic evidence, a direct interaction between TolC and AcrB which is stabilized by AcrA has been proposed. In addition to stabilizing the interactions between TolC and AcrB, AcrA is also responsible for triggering opening of the TolC aperture by mediating energy flow from AcrB to TolC. By permanently altering the conformation of AcrA, suppressor mutants allow defective TolC or AcrB mutants to regain functional interactions lost by the initial mutations. The data provide the genetic proof for direct interaction between AcrB and that AcrA mediated opening of TolC requires AcrB as a scaffold.
ContributorsWeeks, Jon William (Author) / Misra, Rajeev (Thesis advisor) / Stout, Valerie (Committee member) / Shi, Yixin (Committee member) / Clark-Curtiss, Josephine (Committee member) / Arizona State University (Publisher)
Created2012
Description
First-semester student retention is a constant priority for undergraduate institutions. The transition to the collegiate level, and to a new scholastic program and format, is frequently challenging academically and socially—for this reason, many first-semester course schedules for incoming freshman undergraduates feature an introductory seminar to ease transition to an undergraduate lifestyle. Arizona State University features a required “Careers in the Life Sciences” course for its first-semester School of Life Sciences students, which has had tractable results in first semester student retention and academic success. Here, we evaluate a component of the seminar, the peer-mentorship program, for its efficacy in students’ first semester experience. Analysis of self-reports from 168 first-semester “mentees” and their 25 mentors indicates frequency of mentee-mentor contact was the best indicator of a higher first semester GPA, comfort with academic resources and study habits, and desire to engage in extracurricular activities and internships. These data indicate that access to a mentor who actively engages and verbally connects with their mentees is a valuable component of first-semester student academic integration and retention.
ContributorsMathews, Ian T. (Author) / Capco, David (Thesis director) / Clark-Curtiss, Josephine (Committee member) / Harrell, Carita (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2014-05
Description
Stress, empathy, and emotion regulation are factors that can greatly shape an individual's behavior, thoughts, and physiology. The degree to which an individual experiences stress, demonstrates empathy, or is able to regulate emotions can influence his or her ability to establish strong social bonds. The current study investigated the relationships among stress, empathy, and emotion regulation and considered gender differences in these relationships. I hypothesized that higher levels of current stress would be associated with lower levels of empathy and greater difficulties with emotion regulation, and that empathy and emotion regulation would be positively related. Supporting these hypotheses, the following relationships were found: (a) negative correlation between stress and empathy, (b) positive correlation between stress and emotion regulation difficulties, and (c) negative correlation between empathy and emotion regulation difficulties. Results also revealed that greater perceived stress was associated with less empathy in women, but it was unrelated to empathy in men. On the other hand, stress was associated with greater emotion regulation difficulties in both men and women, indicating that either gender may experience a greater disturbance in their emotional response within a social situation when under the influence of stress. Empathy and emotion regulation are positively correlated in both genders, which might suggest that high emotion regulation may allow for appropriate empathy responses within a given social context.
ContributorsHanna, Rand Maria (Author) / Roberts, Nicole (Thesis director) / Burleson, Mary (Committee member) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor) / School of Social and Behavioral Sciences (Contributor)
Created2016-12
Description
How early life is experienced and perceived can greatly affect mental and physical health outcomes. An individual is greatly influenced by their first models of what social relationships look and feel like, and with time also learn how to survive when less favorable social experiences occur. The lessons learned may lead to healthy problem solving and resilience, or it may lead to unhealthy problem-solving habits that hinder well-being. Anxious thoughts and other mental health symptoms may accompany an individual long-term and hinder an essential need for a healthy life. The first main purpose of this thesis is to examine the impact of Adverse Childhood Experiences (ACEs) on mental health (anxiety symptoms), and on sleep quality (an essential need). The second purpose of my thesis is to investigate the impact of genetics on resilience, specifically, the mu-opioid receptor gene. The first hypothesis proposed ACEs that were perceived as more traumatic and occurred more frequently would be associated with more poor sleep quality symptoms. The second hypothesis predicted that anxiety symptoms would mediate the association. The third hypothesis (exploratory) suggested that an individual’s alleles for the mu-opioid receptor gene would moderate the mediation pathway. The study was conducted with 318 participants between the ages of 18 and 35 years old. The study demonstrated a direct effect for ACEs and sleep. Anxiety mediated the association between ACEs (exposure and severity) and sleep (insomnia, quality, sleepiness), suggesting that ACEs possibly increase feelings of anxiety which, in turn, lead to worse sleep outcomes. Finally, the moderated-mediation model with OPRM1 as the moderator, was not significant for the mediation pathway A; however, there was a significant interaction with anxiety and sleep symptoms.
ContributorsBailey, Elise (Author) / Mickelson, Kristin (Thesis advisor) / Burleson, Mary (Committee member) / Petrov, Megan (Committee member) / Arizona State University (Publisher)
Created2022
Description
With widespread increases in the use of electronic communication technology, cyber-sexual harassment (CSH) has been on the rise. Broadly defined, CSH is unwelcome and repeated conduct of a sexual nature performed through electronic technology. The prevalence of CSH reported in previous studies varies significantly due in part to inconsistencies in how CSH is defined and measured. Whereas four existing scales measuring aspects of CSH have been published, each has several limitations. This research aims to develop and psychometrically validate the Multidimensional Cyber-Sexual Harassment Experiences and Attitudes Scale for Victimization (MCSHEA-V), which taps into five key components of CSH, including: (1) gathering sexual information online, (2) image and video-based sexual harassment, (3) offensive comments or posts, (4) coercive behaviors, and (5) CSH attitudes. In Study 1, a sample of psychology graduate students and faculty (N = 13) evaluated the content validity of the MCSHEA-V items, leading to key improvements in item relevance, clarity, and wording. In Study 2, a sample of adult participants (N = 298) completed the initial version of the scale through the online survey platform, Prolific.co. Confirmatory factor analyses indicated the proposed 5-factor structure was a good fit, but exploratory factor analyses indicated the items represented an alternative 4-factor structure. Specifically, these items captured dyadic CSH behaviors, CSH behaviors that affect one’s reputation, perceptions of the seriousness of CSH, and CSH victim-blaming behaviors. In Study 3, an additional sample of adult participants (N = 207) was surveyed via Prolific.co. Separate confirmatory factor analyses indicated the 4-factor model was the best fit. Overall, the MCSHEA-V will contribute to a clearer understanding of the defining features and prevalence of CSH victimization and facilitate future research through the introduction of a psychometrically-validated measurement tool.
ContributorsWheeler, Brittany (Author) / Hall, Deborah (Thesis advisor) / Mickelson, Kristin (Committee member) / Burleson, Mary (Committee member) / Arizona State University (Publisher)
Created2022
Description
Given the prevalence and severity of dating violence (DV) in our World, uncovering the long-term effects of DV is pivotal. This thesis provides information about how prior DV impacts a survivor’s future relationships. First, understanding the association between prior DV and current relationship satisfaction. Next, suggesting potential moderators between DV and current relationship satisfaction in forms of resilience. Tangible resilience strategies such as seeking therapy and obtaining an order of protection were assessed as potential moderators. As well as one’s attachment style as a predictor of how one overcomes prior DV and impacts current relationship satisfaction. A study was conducted with 218 participants from both the United States and international countries. Prior DV was a predictor of relationship satisfaction, however in the adverse way as predicted. Survivors of prior dating violence reported higher levels of current relationship satisfaction. Tangible resilience and secure attachment style were both significant moderators of the relationship between prior DV and current relationship satisfaction. These results present new ways to face the challenge of overcoming the repercussions of DV for survivors. As well as provide hope and support to all survivors of DV that their past does not have to impact their future.
ContributorsGraham, Kaylyn (Author) / Mickelson, Kristin (Thesis advisor) / Randall, Ashley (Committee member) / Burleson, Mary (Committee member) / Arizona State University (Publisher)
Created2022
Description
Behavioral, electrophysiological, and neuroimaging evidence has demonstrated that multiple object tracking (MOT) tasks draw upon visual perception, attention, and working memory cognitive processes. Functional neuroimaging studies identified the middle temporal visual area (MT+/V5) as one of several brain regions associated with MOT in humans. MT+/V5 is thought to be responsible for processing motion from visual information, regulating smooth pursuit eye movements, and encoding memory for motion. However, it is unclear how MT+/V5 interacts with attention and working memory performance processes during MOT. To investigate this question, the right MT+/V5 region was identified in 14 neurotypical subjects using structural magnetic resonance imaging (sMRI). The right MT+/V5 was stimulated using intermittent theta-burst stimulation (iTBS), continuous theta-burst stimulation (cTBS), and sham transcranial magnetic stimulation (TMS) using a within-subjects design. Average MOT performance was measured before and 5-min, 30-min, and 60-min after each stimulation protocol. There was no significant difference in average MOT performance across time, regardless of the stimulation condition.
ContributorsAlucard, Myles (Author) / Duran, Nicholas (Thesis advisor, Committee member) / Brewer, Gene (Thesis advisor, Committee member) / Burleson, Mary (Committee member) / Arizona State University (Publisher)
Created2023