Epistatic Relationships between sarA and agr in Staphylococcus aureus Biofilm Formation

Background: The accessory gene regulator (agr) and staphylococcal accessory regulator (sarA) play opposing roles in Staphylococcus aureus biofilm formation. There is mounting evidence to suggest that these opposing roles are therapeutically relevant in that mutation of agr results in increased biofilm formation and decreased antibiotic susceptibility while mutation of sarA has the opposite effect. To the extent that induction of agr or inhibition of sarA could potentially be used to limit biofilm formation, this makes it important to understand the epistatic relationships between these two loci. Methodology/Principal Findings: We generated isogenic sarA and agr mutants in clinical isolates of S. aureus and assessed the relative impact on biofilm formation. Mutation of agr resulted in an increased capacity to forma biofilmin the 8325-4 laboratory strain RN6390 but had little impact in clinical isolates S. aureus. In contrast, mutation of sarA resulted in a reduced capacity to form a biofilm in all clinical isolates irrespective of the functional status of agr. This suggests that the regulatory role of sarA in biofilm formation is independent of the interaction between sarA and agr and that sarA is epistatic to agr in this context. This was confirmed by demonstrating that restoration of sarA function restored the ability to form a biofilm even in the corresponding agr mutants. Mutation of sarA in clinical isolates also resulted in increased production of extracellular proteases and extracellular nucleases, both of which contributed to the biofilm-deficient phenotype of sarA mutants. However, studies comparing different strains with and without proteases inhibitors and/or mutation of the nuclease genes demonstrated that the agr-independent, sarA-mediated repression of extracellular proteases plays a primary role in this regard. Conclusions and Significance: The results we report suggest that inhibitors of sarA-mediated regulation could be used to limit biofilm formation in S. aureus and that the efficacy of such inhibitors would not be limited by spontaneous mutation of agr in the human host

Exploring Potential Benefits and Ramifications of the Superwoman Schema on Cardiovascular Health

Is the Superwoman Schema (SWS) health deleterious or health beneficial, and do specific aspects play a role? The Superwoman role has demonstrated negative relations to mental health. However, limited research has investigated the Superwoman role in the context of physical health. Studies that have investigated the physiological repercussions of the Superwoman Schema have been mixed, showing differential impacts of the different dimensions of the Superwoman role. The goals of this dissertation were to examine the Superwoman Schema, which posits that African American women are naturally strong, resilient, and nurturing, shaping the way they experience and interact with the world, and associations between SWS with stress, positive psychological resources, and cardiovascular health. Specifically, this dissertation examined 1) whether the overall SWS and the SWS dimensions were associated with cardiovascular health, 2) whether increased stress burden explain the relation between the SWS and SWS dimensions and cardiovascular health, and 3) whether positive psychological resources buffered the negative aspects of the SWS or enhanced the positive aspects of the SWS on cardiovascular health. Results indicated that contrary to hypotheses, the overall SWS was not associated with cardiovascular health outcomes on its own and stress was not a mediator of SWS and any of the cardiovascular health outcomes. However, three SWS dimensions (i.e., obligation to present an image of strength, motivation to succeed, and obligation to help others) did interact with positive psychological resources in association with nighttime diastolic blood pressure (DBP). At high levels of positive psychological resources, greater endorsement of obligation to present an image of strength, motivation to succeed, and obligation to help others was associated with lower nighttime DBP, while less endorsement of each of these SWS dimensions was linked with higher nighttime DBP. Several individual measures of positive psychological resources (i.e., environmental mastery, optimism, and resilience) also showed significant interactions with either SWS or at least one of the SWS dimensions on indices of cardiovascular health (i.e., pulse wave velocity, nighttime DBP, and combined intima-media thickness). At low levels of mastery, greater SWS endorsement was associated with higher pulse wave velocity, while less SWS endorsement was associated with lower pulse wave velocity. For those high in optimism, greater obligation to present an image of strength was linked with higher nighttime blood pressure, while less obligation to present an image of strength was linked with lower nighttime blood pressure. For those low in optimism and resilience, respectively, greater obligation to care for others was linked with increased intima-media thickness, while less obligation to care for others was linked with less intima-media thickness. Taken together, these findings suggest the importance of assessing the different components of the SWS and how they relate to stress and positive psychological resources to better understand how these factors may relate to health disparities for Black women

Early-life ketamine exposure attenuates the preference for ethanol in adolescent Sprague-Dawley rats

Ketamine, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, produces quick and effective antidepressant results in depressed juvenile and adult individuals. The long-term consequences of using ketamine in juvenile populations are not well known, particularly as it affects vulnerability to drugs of abuse later in life, given that ketamine is also a drug of abuse. Thus, the current study examined whether early-life ketamine administration produces long-term changes in the sensitivity to the rewarding effects of ethanol, as measured using the conditioned place preference (CPP) paradigm. On postnatal day (PD) 21, juvenile male and female rats were pretreated with ketamine (0.0 or 20 mg/kg) for 10 consecutive days (i.e., PD 21-30) and then evaluated for ethanol-induced CPP (0.0, 0.125, 0.5, or 2.0 g/kg) from PD 32 - 39. Results revealed that early-life ketamine administration attenuated the rewarding properties of ethanol in male rats, as ketamine pretreated rats failed to exhibit ethanol-induced CPP at any dose compared to saline pretreated rats, which showed an increased preference towards the ethanol-paired compartment in a dose-dependent manner. In females, ethanol-induced CPP was generally less robust compared to males, but ketamine pretreatment resulted in a rightward shift in the dose-response curve, given that ketamine pretreated rats needed a higher dose of ethanol compared to saline pretreated rats to exhibit ethanol-induced CPP. When considered together, the findings suggest that early use of ketamine does not appear to enhance the vulnerability to ethanol later in life, but in contrast, it may attenuate the rewarding effects of ethanol.18 month embargo; published online: 30 April 2020This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Performance of a Genomic Sequencing Classifier for the Preoperative Diagnosis of Cytologically Indeterminate Thyroid Nodules.

ImportanceUse of next-generation sequencing of RNA and machine learning algorithms can classify the risk of malignancy in cytologically indeterminate thyroid nodules to limit unnecessary diagnostic surgery.ObjectiveTo measure the performance of a genomic sequencing classifier for cytologically indeterminate thyroid nodules.Design, setting, and participantsA blinded validation study was conducted on a set of cytologically indeterminate thyroid nodules collected by fine-needle aspiration biopsy between June 2009 and December 2010 from 49 academic and community centers in the United States. All patients underwent surgery without genomic information and were assigned a histopathology diagnosis by an expert panel blinded to all genomic information. There were 210 potentially eligible thyroid biopsy samples with Bethesda III or IV indeterminate cytopathology that constituted a cohort previously used to validate the gene expression classifier. Of these, 191 samples (91.0%) had adequate residual RNA for validation of the genomic sequencing classifier. Algorithm development and independent validation occurred between August 2016 and May 2017.ExposuresThyroid nodule surgical histopathology diagnosis by an expert panel blinded to all genomic data.Main outcomes and measuresThe primary end point was measurement of genomic sequencing classifier sensitivity, specificity, and negative and positive predictive values in biopsies from Bethesda III and IV nodules. The secondary end point was measurement of classifier performance in biopsies from Bethesda II, V, and VI nodules.ResultsOf the 183 included patients, 142 (77.6%) were women, and the mean (range) age was 51.7 (22.0-85.0) years. The genomic sequencing classifier had a sensitivity of 91% (95% CI, 79-98) and a specificity of 68% (95% CI, 60-76). At 24% cancer prevalence, the negative predictive value was 96% (95% CI, 90-99) and the positive predictive value was 47% (95% CI, 36-58).Conclusions and relevanceThe genomic sequencing classifier demonstrates high sensitivity and accuracy for identifying benign nodules. Its 36% increase in specificity compared with the gene expression classifier potentially increases the number of patients with benign nodules who can safely avoid unnecessary diagnostic surgery

Performance of a Genomic Sequencing Classifier for the Preoperative Diagnosis of Cytologically Indeterminate Thyroid Nodules.

Importance:Use of next-generation sequencing of RNA and machine learning algorithms can classify the risk of malignancy in cytologically indeterminate thyroid nodules to limit unnecessary diagnostic surgery. Objective:To measure the performance of a genomic sequencing classifier for cytologically indeterminate thyroid nodules. Design, Setting, and Participants:A blinded validation study was conducted on a set of cytologically indeterminate thyroid nodules collected by fine-needle aspiration biopsy between June 2009 and December 2010 from 49 academic and community centers in the United States. All patients underwent surgery without genomic information and were assigned a histopathology diagnosis by an expert panel blinded to all genomic information. There were 210 potentially eligible thyroid biopsy samples with Bethesda III or IV indeterminate cytopathology that constituted a cohort previously used to validate the gene expression classifier. Of these, 191 samples (91.0%) had adequate residual RNA for validation of the genomic sequencing classifier. Algorithm development and independent validation occurred between August 2016 and May 2017. Exposures:Thyroid nodule surgical histopathology diagnosis by an expert panel blinded to all genomic data. Main Outcomes and Measures:The primary end point was measurement of genomic sequencing classifier sensitivity, specificity, and negative and positive predictive values in biopsies from Bethesda III and IV nodules. The secondary end point was measurement of classifier performance in biopsies from Bethesda II, V, and VI nodules. Results:Of the 183 included patients, 142 (77.6%) were women, and the mean (range) age was 51.7 (22.0-85.0) years. The genomic sequencing classifier had a sensitivity of 91% (95% CI, 79-98) and a specificity of 68% (95% CI, 60-76). At 24% cancer prevalence, the negative predictive value was 96% (95% CI, 90-99) and the positive predictive value was 47% (95% CI, 36-58). Conclusions and Relevance:The genomic sequencing classifier demonstrates high sensitivity and accuracy for identifying benign nodules. Its 36% increase in specificity compared with the gene expression classifier potentially increases the number of patients with benign nodules who can safely avoid unnecessary diagnostic surgery