Matching Items (98)
Description
This work comprises a cumulative effort to provide analysis of proteins relevant to understanding and treating human disease. This dissertation focuses on two main protein complexes: the structure of the Chimp adenovirus Y25 capsid assembly, as used in the SARS-CoV-2 vaccine, Vaxzveria, and the Dbl family RhoGEF (guanosine exchange factor) Syx and its associated small G protein, RhoA. The course of research was influenced heavily by the onset of the Covid-19 pandemic and associated lockdown, which pushed anyone with the means to do meaningful research to shift priorities towards addressing the greatest public health crisis since the 1918 flu pandemic.
Analysis of the Syx-RhoA complex for the purposes of structurally guided drug design was initially the focus of heavy optimization efforts to overcome the numerous challenges associated with expression, purification, and handling of this protein. By analyzing E. Coli derived protein new important knowledge was gained about this protein’s biophysical characteristics which contribute to its behavior and may inform drug design efforts. Expression in SF9 insect cells resulted in promising conditions for production of homogeneous and monodispersed protein. Homology modeling and molecular dynamics simulation of this protein support hypotheses about its interactions with both RhoA as well as regions of the cytoplasmic leaflet of the cell membrane.
Structural characterization of ChAdOx1, the adenoviral vector used in the AstraZeneca Covid-19 vaccine, Vaxzveria resulted in the highest resolution adenovirus structure ever solved (3.07Å). Subsequent biochemical analysis and computational simulations of PF4 with the ChAdOx1 capsid reveal interactions with important implications for vaccine induced thrombocytic throbocytopenia syndrome, a disorder observed in approximately 0.000024% of patients who receive Vaxzveria.
ContributorsBoyd, Ryan J (Author) / Fromme, Petra (Thesis advisor) / Chiu, Po-Lin (Committee member) / Liu, Wei (Committee member) / Arizona State University (Publisher)
Created2021
Description
Particulate Guanylyl Cyclase Receptor A (pGC-A) is an atrial natriuretic peptide receptor, which plays a vital role in controlling cardiovascular, renal, and endocrine functions. The extracellular domain of pGC-A interacts with natriuretic peptides and triggers the intracellular guanylyl cyclase domain to convert GTP to cGMP. To effectively develop a method that can regulate pGC-A, structural information regarding its intact form is necessary. Currently, only the extracellular domain structure of rat pGC-A has been determined. However, structural data regarding the transmembrane domain, as well as functional intracellular domain regions, need to be elucidated.This dissertation presents detailed information regarding pGC-A expression and optimization in the baculovirus expression vector system, along with the first purification method for purifying functional intact human pGC-A. The first in vitro evidence of a purified intact human pGC-A tetramer was detected in detergent micellar solution. Intact pGC-A is currently proposed to function as a homodimer. Upon analyzing my findings and acknowledging that dimer formation is required for pGC-A functionality, I proposed the first tetramer complex model composed of two functional subunits (homodimer). Forming tetramer complexes on the cell membrane increases pGC-A binding efficiency and ligand sensitivity.
Currently, a two-step mechanism has been proposed for ATP-dependent pGC-A signal transduction. Based on cGMP functional assay results, it can be suggested that the binding ligand also moderately activates pGC-A, and that ATP is not crucial for the activation of guanylyl cyclase. Instead, three modulators can regulate different activation levels in intact pGC-A.
Crystallization of purified intact pGC-A was performed to determine its structure. During the crystallization condition screening process, I successfully selected seven promising initial crystallization conditions for intact human pGC-A crystallization. One selected condition led to the formation of excellent needle-shaped crystals. During the serial crystallography diffraction experiment, five diffraction patterns were detected. The highest diffraction resolution spot reached 3 Å.
This work will allow the determination of the intact human pGC-A structure while also providing structural information on the protein signal transduction mechanism. Further structural knowledge may potentially lead to improved drug design. More precise mutation experiments could help verify the current pGC-A signal transduction and activation mechanism.
ContributorsZhang, Shangji (Author) / Fromme, Petra (Thesis advisor) / Johnston, Stephen (Committee member) / Mazor, Yuval (Committee member) / Arizona State University (Publisher)
Created2021
Purification, Characterization, and Structural Determination of Proteins Vital to Infectious Disease
Description
The work in this dissertation progressed the research of structural discovery for two targets critical in the fight of infectious disease. Francisella lipoprotein 3 (Flpp3) is a virulent determinant of tularemia and was the first protein of study. The proteins soluble domain was studied using a hybrid modeling theory that used small angle X-ray scattering (SAXS) in combination with computation analysis to generate a SAXS-refined structure. The SAXS-refined structure closely resembled the NMR structure (PDB: 2MU4) which contains a hydrophobic cavity inside the protein that could be used for drug discovery purposes. The full-length domain of Flpp3 purified from the outer membrane of E. coli was also studied with a combination of biophysical characterization methods. Mass spectrometry and western blot analysis confirmed Flpp3 being translocated to the outer membrane, while SDS-PAGE confirmed the purity of Flpp3 in the monomeric form after size exclusion chromatography. Using Circular Dichroism (CD) the monomeric form of Flpp3 was shown to be almost fully refolded into having a primarily β-stranded secondary structure. This information advances the progress of both tularemia research and outer membrane protein research as no natively folded outer membrane protein structures have been solved for F. tularensis.The second protein worked on in this dissertation is the nonstructural protein 15 from SARS-CoV-2, also called NendoU. Nsp15 is an endoribonuclease associated with aiding the virus responsible for the current COVID-19 pandemic in evasion of the immune system. An inactive mutant of Nsp15 was studied with both negative stain electron microscopy and cryogenic electron microscopy (Cryo-EM) in the presence of RNA or without RNA present. The initial findings of negative stain electron microscopy of Nsp15 with and without RNA showed a difference in appearance. Negative stain analysis of Nsp15 is in the presence of a 5nt RNA sequence in low salt conditions shows a conformational change when compared to Nsp15 without RNA present. As well the presence of RNA appeared to shift the electron density in Cryo-EM studies of Nsp15. This work advances the research in how Nsp15 may bind and cleave RNA and aid in the evasion of the host cell immune system.
ContributorsGoode, Matthew (Author) / Fromme, Petra (Thesis advisor) / Guo, Jia (Committee member) / Chiu, Po-Lin (Committee member) / Arizona State University (Publisher)
Created2022
Description
Infectious diseases are the third leading cause of death in the United States and the second leading cause of death in the world. This work aims to advance structural studies of vital proteins involved in the infection process of both a bacterial and a viral infectious disease in hopes of reducing infection, and consequently, fatality rates. The first protein of interest is OspA, a major outer surface protein in Borrelia burgdorferi – the causative bacterium of Lyme disease. Previous functional studies of OspA allude to both a role in colonization of B. burgdorferi in the tick vector and in evasion of the human immune system. This work describes the first ever structural studies of OspA as it is seen by the immune system: in the outer membrane. OspA was expressed in and purified from the outer membrane of Escherichia coli prior to characterization via circular dichroism (CD), native polyacrylamide gel electrophoresis, and electron microscopy. Characterization studies of OspA provide the first evidence of multimeric formation of OspA when translocated to the outer membrane, which presents a new perspective from which to build upon for the design of vaccinations against Lyme disease. The second protein of interest is nonstructural protein 15 (Nsp15), a protein responsible for facilitating immune system evasion of SARS-CoV-2 – the virus responsible for the COVID-19 pandemic. Nsp15 functions to enzymatically cleave negative sense viral RNA to avoid recognition by the human immune system. The work described in this dissertation is dedicated to the electron microscopy work utilized to reveal structural information on an inactive variant of Nsp15 bound to RNA sequences. Negative stain electron microscopy was used to verify Nsp15 structural integrity, as well as reveal a low-resolution image of structural deviation when RNA is bound to Nsp15. Cryo-electron microscopy was performed to solve structural density of Nsp15 without RNA to a resolution of 3.11 Å and Nsp15 bound to 5-nucleotides of RNA to a resolution of 3.99 Å. With further refinement, this structure will show the first structural data of Nsp15 bound to a visible RNA sequence, revealing information on the binding and enzymatic activity of Nsp15.
ContributorsKaschner, Emily (Author) / Fromme, Petra (Thesis advisor) / Hansen, Debra T (Committee member) / Chiu, Po-Lin (Committee member) / Arizona State University (Publisher)
Created2022
Advanced Practice Registered Nurse Led Transitional Care Program in an Accountable Care Organization
Description
Purpose: Reduce or prevent readmissions among heart failure (HF) patients and increase quality of life (QOL), self-care behavior (SCB) and satisfaction through an advanced practice registered nurse (APRN) led transitional care program (TCP) in collaboration with an Accountable Care Organization (ACO).
Background: Hospital readmissions place a heavy financial burden on patients, families, and health care systems. Readmissions can be reduced or prevented by providing a safe transition through care coordination and enhanced communication. Research demonstrates implementation of APRN led home visits (HV) along with telephonic follow-up are cost effective and can be utilized for reducing readmissions among HF patients.
Methods: A program was designed with an ACO and carried out in a family practice clinic with a group of seven HF patients older than 50 years who were at risk of readmission. Interventions included weekly HV with supplemental telephonic calls by the APRN student along with a physician assistant for 12 weeks. Readmission data was collected. QOL and SCB were measured using “Minnesota Living with Heart Failure Questionnaire” (MLHFQ) and “European Heart Failure Self-Care Behavior Scale” respectively. Data was analyzed using descriptive statistics and the Friedman Test.
Outcomes: There were no hospital readmissions at 30 days and the interventions demonstrated a positive effect on QOL, self-care management and satisfaction (χ2 = 30.35, p=.000). The intervention had a large effect on the outcome variables resulting in an increase in QOL and SCB scores post-intervention (ES= -1.4 and -2 respectively).
Conclusions: TCP designed with an ACO, carried out in a primary care setting has a positive effect on reducing hospital readmissions and improving QOL, SCBs, and patient satisfaction among HF patients. TCPs are not revenue generating at outset due to reimbursement issues, however future considerations of a multidisciplinary team approach with convenient workflow may be explored for long-term feasibility and sustainability.
Funding Source: American Association of Colleges of Nursing and the Centers for Disease Control and Prevention with support of the Academic Partners to Improve Health.
Background: Hospital readmissions place a heavy financial burden on patients, families, and health care systems. Readmissions can be reduced or prevented by providing a safe transition through care coordination and enhanced communication. Research demonstrates implementation of APRN led home visits (HV) along with telephonic follow-up are cost effective and can be utilized for reducing readmissions among HF patients.
Methods: A program was designed with an ACO and carried out in a family practice clinic with a group of seven HF patients older than 50 years who were at risk of readmission. Interventions included weekly HV with supplemental telephonic calls by the APRN student along with a physician assistant for 12 weeks. Readmission data was collected. QOL and SCB were measured using “Minnesota Living with Heart Failure Questionnaire” (MLHFQ) and “European Heart Failure Self-Care Behavior Scale” respectively. Data was analyzed using descriptive statistics and the Friedman Test.
Outcomes: There were no hospital readmissions at 30 days and the interventions demonstrated a positive effect on QOL, self-care management and satisfaction (χ2 = 30.35, p=.000). The intervention had a large effect on the outcome variables resulting in an increase in QOL and SCB scores post-intervention (ES= -1.4 and -2 respectively).
Conclusions: TCP designed with an ACO, carried out in a primary care setting has a positive effect on reducing hospital readmissions and improving QOL, SCBs, and patient satisfaction among HF patients. TCPs are not revenue generating at outset due to reimbursement issues, however future considerations of a multidisciplinary team approach with convenient workflow may be explored for long-term feasibility and sustainability.
Funding Source: American Association of Colleges of Nursing and the Centers for Disease Control and Prevention with support of the Academic Partners to Improve Health.
ContributorsSugathan, Kala (Author) / Nunez, Diane (Thesis advisor)
Created2017-05-02
Description
Background: As the nation’s population ages and the prevalence of chronic diseases, like dementia, increases, informal caregivers will play an increasingly important role in maintaining independence for the elderly. Informal caregivers provide most long-term care for the elderly in this country and save hundreds of billions of dollars in healthcare costs annually. However, most informal caregivers experience burden secondary to caregiving that adversely impacts their physical, social, and/or psychological health. Caregiver burden threatens caregiver health and contributes to institutionalization of care recipients. Since the program of all-inclusive care for the elderly (PACE) model of care delivery relies heavily on informal caregivers to maintain independent aging, understanding and meeting the needs of caregivers is essential to the sustainability and success of PACE programs.
Purpose: This evidence-based practice (EBP) project was a gap analysis that surveyed 156 caregivers at an urban PACE program in the Midwest to examine caregiver demographics, caregiver burden, caregiver interest in support services, and the relationship between these variables to guide the development of caregiver programs.
Methods: Caregiver Assessments were administered to 156 caregivers via telephone or in person. The assessment included caregiver demographics, interest in caregiver services, and the 12-item Zarit Burden Interview (ZBI-12) to assess caregiver burden. The ZBI-12 has good reliability and validity as indicated by a Cronbach’s alpha of 0.88 and a correlation with the full version ZBI scores of 0.95. Results were analyzed using descriptive statistics, the Pearson r correlation test, the Wilcoxon signed rank test, and the Mann-Whitney U test on SPSS version 25. This project was approved by the Arizona State University IRB.
Results/Outcomes: Of 171 eligible informal caregivers of program participants living outside of an institution, 156 completed the survey, 3 refused, and 12 were unreachable. Most informal caregivers surveyed were Caucasian (69.5%) females (66%), children of the care recipients (45.5%), caring for people with dementia (40.6%), with some college education (37.2%), who earned $10,000-$25,000 annually (38.7%), provided over 30 hours of care per week (55.8%), and averaged 61.4 years old (SD=7.7). The average ZBI-12 score was 12.15 (SD=9.04), indicating a moderate level of burden. The most common stressors indicated by caregivers were activities of daily living (ADL) assistance (63.5%) and the time commitment involved in caregiving (57.7%). Correlates to high burden score included: limited time, aggressive behavior, financial stress, grief, assistance with ADLs, wandering behavior, toileting assistance/incontinence, and lack of sleep. Respite care was identified by 42.9% of those surveyed as the most helpful resource provided by PACE. 55.1% and 50.6% of caregivers indicated an interest in educational sessions and support groups respectively, if these services were offered in the future.
Conclusion: Through the exploration of caregiver demographics, factors correlated to increased burden, and caregiver interest in support services, the results from this EBP project provide guidance to programs, particularly other PACE programs, seeking to proactively mitigate caregiver burden through support services. The results indicate that respite care, educational sessions, and support groups should be prioritized when developing informal caregiver support services.
Purpose: This evidence-based practice (EBP) project was a gap analysis that surveyed 156 caregivers at an urban PACE program in the Midwest to examine caregiver demographics, caregiver burden, caregiver interest in support services, and the relationship between these variables to guide the development of caregiver programs.
Methods: Caregiver Assessments were administered to 156 caregivers via telephone or in person. The assessment included caregiver demographics, interest in caregiver services, and the 12-item Zarit Burden Interview (ZBI-12) to assess caregiver burden. The ZBI-12 has good reliability and validity as indicated by a Cronbach’s alpha of 0.88 and a correlation with the full version ZBI scores of 0.95. Results were analyzed using descriptive statistics, the Pearson r correlation test, the Wilcoxon signed rank test, and the Mann-Whitney U test on SPSS version 25. This project was approved by the Arizona State University IRB.
Results/Outcomes: Of 171 eligible informal caregivers of program participants living outside of an institution, 156 completed the survey, 3 refused, and 12 were unreachable. Most informal caregivers surveyed were Caucasian (69.5%) females (66%), children of the care recipients (45.5%), caring for people with dementia (40.6%), with some college education (37.2%), who earned $10,000-$25,000 annually (38.7%), provided over 30 hours of care per week (55.8%), and averaged 61.4 years old (SD=7.7). The average ZBI-12 score was 12.15 (SD=9.04), indicating a moderate level of burden. The most common stressors indicated by caregivers were activities of daily living (ADL) assistance (63.5%) and the time commitment involved in caregiving (57.7%). Correlates to high burden score included: limited time, aggressive behavior, financial stress, grief, assistance with ADLs, wandering behavior, toileting assistance/incontinence, and lack of sleep. Respite care was identified by 42.9% of those surveyed as the most helpful resource provided by PACE. 55.1% and 50.6% of caregivers indicated an interest in educational sessions and support groups respectively, if these services were offered in the future.
Conclusion: Through the exploration of caregiver demographics, factors correlated to increased burden, and caregiver interest in support services, the results from this EBP project provide guidance to programs, particularly other PACE programs, seeking to proactively mitigate caregiver burden through support services. The results indicate that respite care, educational sessions, and support groups should be prioritized when developing informal caregiver support services.
ContributorsCraft-Otterbacher, Erin (Author) / Nunez, Diane (Thesis advisor)
Created2019-04-30
Description
This work focuses on a novel approach to combine electrical current with cyanobacterial technology, called microbial electrophotosynthesis (MEPS). It involves using genetically modified PSII-less Synechocystis PCC 6803 cells to avoid photoinhibition, a problem that hinders green energy. In the work, a cathodic electron delivery system is employed for growth and synthesis. Photoinhibition leads to the dissipation energy and lower yield, and is a major obstacle to preventing green energy from competing with fossil fuels. However, the urgent need for alternative energy sources is driven by soaring energy consumption and rising atmospheric carbon dioxide levels. When developed, MEPS can contribute to a carbon capture technology while helping with energy demands. It is thought that if PSII electron flux can be replaced with an alternative source photosynthesis could be enhanced for more effective production. MEPS has the potential to address these challenges by serving as a carbon capture technology while meeting energy demands. The idea is to replace PSII electron flux with an alternative source, which can be enhanced for higher yields in light intensities not tolerated with PSII. This research specifically focuses on creating the initiation of electron flux between the cathode and the MEPS cells while controlling and measuring the system in real time.
The successful proof-of-concept work shows that MEPS can indeed generate high-light-dependent current at intensities up to 2050 µmol photons m^‒2 s^‒1, delivering 113 µmol electrons h^‒1 mg-chl^‒1. The results were further developed to characterize redox tuning for electron delivery of flux to the photosynthetic electron transport chain and redox-based kinetic analysis to model the limitations of the MEPS system.
ContributorsLewis, Christine Michelle (Author) / Torres, César I (Thesis advisor) / Fromme, Petra (Thesis advisor) / Woodbury, Neal (Committee member) / Hayes, Mark (Committee member) / Arizona State University (Publisher)
Created2023
Description
Substance use disorder has been increasing in the United States year after year. Modern treatments fail as often as they succeed. The current standards of practice fail to provide patients with the ability to harness thoughts and control anxiety. Mindfulness practices are currently being adapted as a therapeutic technique to address some of these concerns. An exhaustive literature review was conducted to investigate how various mindfulness techniques impact substance use disorder. Ten high-quality studies were retained and synthesized to show current understandings of the effectiveness of a mindfulness therapeutic technique. An evidence-based intervention is suggested for implementing mindfulness-based relapse prevention into a residential treatment facility. The intervention created incorporates the self-efficacy theory and an adapted health-belief model. Adults in a residential treatment facility for substance use disorder were given eight mindfulness sessions over the course of four weeks. Participants were given pre- and post-intervention screenings for mindful attention and anxiety. The data analysis after two-tailed paired T-tests showed that anxiety significantly decreased (α=.05, p<.001) and mindful attention increased significantly (α=.05, p=.015). Overall, mindfulness shows promise in its potential to reduce substance abuse.
ContributorsWandler, Ryan (Author) / Nunez, Diane (Thesis advisor) / College of Nursing and Health Innovation (Contributor)
Created2023-04-27
Description
Problem Statement: The onset of the COVID-19 pandemic led to intense challenges for health care providers. Outpatient primary care practices rapidly moved from in-person practice to video-conferencing telehealth appointments. This shift requires study, particularly how this has impacted the lived experience of providers.
Purpose: This project aims to explore primary care provider satisfaction with telehealth in the wake of the COVID-19 pandemic.
Methods: A point-in-time survey was administered to primary care providers at a large university health system. Participants were recruited at a monthly provider meeting and invited to complete an anonymous online survey. Satisfaction with video-conferencing patient visits was explored via Likert scale and write-in responses. Providers highlighted specific complaints, problems, and successes that impacted their practice and patients. Aggregate health data from this organization was also obtained for comparison. Statistical analysis was performed and recommendations made for future practice.
Findings: The provider experience of telehealth was overwhelmingly positive. 85% (n=11) of providers agreed or strongly agreed that telehealth allows them to manage their patients effectively. Lack of physical exam findings was the most commonly cited concern (n=9). 100% (n=13) of providers would like to continue seeing patients via telehealth in the future.
Conclusion: Videoconferencing appointments in university health primary care promote high provider satisfaction. Future policies and innovations should support the use of a telehealth platform.
ContributorsMcKernan, M. Katherine (Author) / Nunez, Diane (Thesis advisor) / College of Nursing and Health Innovation (Contributor)
Created2023-04-29
Description
The complex network of the immune system defends the human body against infection, providing protection from pathogens. This work aims to improve preparation and structural knowledge of two proteins on opposite sides of the immune system spectrum. The first protein, secreted autotransporter toxin (Sat) is a class I serine protease autotransporter of Enterobacteriaceae (SPATE) that has cytotoxic and immunomodulatory effects on the host. Previous studies on Sat show its ability to aid in bacterial colonization and evasion of the immune system. This work improves the stability of Sat by making mutations to the active serine protease motif (GDSGS) while inhibiting remaining activity with reversible and irreversible serine protease inhibitors. Characterization of Sat by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and size-exclusion chromatography led to the first structural studies of Sat by x-ray crystallography and cryo-EM. Human leukocyte antigen class I proteins play an important role in the adaptive immune system by presenting endogenous viral peptides at the cell surface for CD8+ T cell recognition. In vitro production of HLA-I proteins is a difficult task without endoplasmic reticulum chaperones as present in vivo. Disulfide bond formation, folded light chain and a peptide bound are all key to refolding the HLA-I heavy chain for complex formation. The work presented in this dissertation represents systematic studies aimed at improving the production of HLA-I proteins in vitro in bacterial expression systems. Optimization of every step of the preparation was investigated providing higher expression yields, quality of inclusion bodies, and refolding improvements. With further improvements in the future, this work forms the basis for a more efficient small and large-scale production of HLA-I molecules for functional and structural studies.
ContributorsKiefer, Dalton (Author) / Anderson, Karen (Thesis advisor) / Fromme, Petra (Thesis advisor) / Chiu, Po-Lin (Committee member) / Mazor, Yuval (Committee member) / Arizona State University (Publisher)
Created2024