Full text for dissertations and theses included in this collection dates back to 2011. For older dissertations, check the library’s catalog CatalogUSMAI or Dissertations and Theses.

Recent Submissions

  • Assessing the Impact of the Affordable Care Act Reimbursement Policy on the Medicare Home Health Care Market and Implications for Beneficiaries

    Torain, Jamila; Davitt, Joan K.; Orwig, Denise L.; 0000-0002-5174-4865 (2019)
    The current study examined the impact of the recent Affordable Care Act (ACA) reimbursement cuts on the Medicare Home Health Care (HHC) market. First, the number of new agencies, number of agencies that exited the market, and the number of active agencies were counted, 2010-2017, in order to determine the rate of change between time periods. Next, the difference in average HHC staff count was determined. Then, using logistic regression, the odds of agency termination and the odds of agency decrease in staff by agency characteristics, was determined for both periods. Finally, qualitative interviews were conducted with 13 HHC directors to further explore their experiences during the reimbursement cuts. Free standing agencies had 1.35 times the odds of exiting from the HHC market post ACA cuts compared to institution-based agencies. There were no differences in the odds of exiting the HHC market between for-profit and non-profit agencies. Agencies in the New York, Atlanta, and Chicago regions had a greater likelihood of exiting the HHC market post ACA cuts. Small agencies had two times the odds of exiting and agencies with one or more branch had less than half the odds of exiting from the HHC market. The average number of all staff was similar before and after the ACA cuts; however, office staff and home health aides experienced the greatest decrease in number. Agencies that were for-profit, free-standing, small, and/or with one or more branch were more likely to decrease staff post the ACA cuts. Agencies in the New York, Atlanta, Chicago, Dallas and Kansas regions were more likely to decrease staff. Similar to existing research, the strategies used to manage the reimbursement cuts either focused on reducing the amount of service to patients, the intensity of service, or on cutting costs for supplies, staff travel and support services. In addition, agencies indicated relying more heavily on informal caregivers. Overall, the policy effects varied by geographic region and had greater impact on more vulnerable agencies and staff that were non-skilled. Strategies utilized during this time had the potential to negatively impact access to and quality of care for Medicare beneficiaries.
  • THE EFFECT OF HYPERTHERMIA AND PROTON RADIATION THERAPY ON CHORDOMA CELLS

    Singh, Prerna R; Mahmood, Javed (2019)
    Chordomas are a rare slow-growing cancer and their standard of care is surgery with Radiotherapy (RT). Chordoma is highly radioresistant and requires high dose of RT that lead to toxicity in the surrounding tissues. We investigated whether proton beam radiation therapy (PBRT) response can be further enhanced in combination with hyperthermia (HT) as a radiosensitizer. We also explored cell survival at the end of the Spread-out Bragg Peak (E-SOBP) compared to middle of the SOBP (M-SOBP) of PBRT with and without HT. Chordoma cell lines were treated with HT followed by PBRT at both E-SOBP and M-SOBP. Clonogenic assay was performed in triplicates for a dose response survival. HT with PBRT significantly killed (p<0.05) more cells at M-SOBP and E-SOBP compared to PBRT without HT. Our results provide in vitro evidence on effects of HT as a novel additive treatment to increase PBRT effectiveness in Chordoma cell lines.
  • Micro-RNAs as biomarkers and therapeutic targets for autoimmune arthritis

    Dudics, Steven Rudolph; Moudgil, Kamal (2019)
    Rheumatoid arthritis (RA) is a chronic, debilitating autoimmune disease that affects 0.3-1% of the world’s population. Approximately 30-40% of RA patients fail to respond well to presently used drugs, and the prolonged use of these drugs may result in serious adverse effects. Additionally, there are inherent limitations in the current biomarkers for RA with regard to their utility in the diagnosis and monitoring of therapeutic response. Therefore, there is an urgent need for novel therapeutic agents and new biomarkers for better management of RA. We proposed that specific micro-RNAs (miRNAs) can serve both these needs. MiRNAs are 19-22 nucleotides in length, transcribed mostly from the non-coding regions of the genome, and increasingly being recognized as master regulators of gene expression. Using the rat adjuvant-induced arthritis (AA) model of RA, we examined the miRNA expression profile of arthritic rats and determined how this profile is modulated following anti-arthritis therapy. We used celastrol, a bioactive triterpenoid derived from a plant extract (celastrus), as a potential therapeutic. Following statistical and bioinformatical analyses, 8 miRNAs that were found to be increased after arthritis development were selected for further study. The expression of 6 of these miRNAs was significantly modulated by celastrol treatment, and the expression profile of the draining lymphoid cells was different from that of serum. We then identified the genes targeted by specific miRNAs, e.g., miR-96. Using transfection of RAW cells (macrophages) and HUVECs (endothelial cells) with miRNA mimics, we identified the target genes whose products play an important role in osteoclastogenesis and angiogenesis, respectively. Network analysis and functional assays further revealed the effects of select miRNAs on these two arthritis-related processes. Interestingly, the levels of expression of some of these miRNA-regulated genes were altered by celastrol, suggesting their involvement in its anti-arthritic effect. We suggest that the above miRNAs may serve as novel biomarkers of disease activity and therapeutic response in arthritis. A subset of these miRNAs could also be targeted for arthritis therapy.
  • Protein organization and NMDA receptor activation at individual hippocampal synapses.

    Metzbower, Sarah Wein Ransom; Blanpied, Thomas A. (2019)
    Protein organization and receptor activation coordinate to maintain synaptic efficacy at individual synapses. Therefore, it is important to explore both mechanisms that impact how proteins are arranged and factors that influence receptor activation. Transsynaptic cleft proteins are important for synaptogenesis and synapse function but little is known about how they are organized within the cleft. One such transsynaptic protein is Synaptic Cell Adhesion Molecule 1 (SynCAM 1), which has been shown to be important for synaptogenesis and synapse maintenance but its subsynaptic organization had not been explored. Using a combination of high-resolution imaging approaches, including cryoelectron tomography and super-resolution imaging, it was determined that not only does SynCAM 1 form peri-synaptic puncta, but also that the presence of SynCAM 1 is required for normal protein density distribution within the synaptic cleft. Thus supporting the idea that the synapse is organized into nano-compartments and that SynCAM 1 may be important for this subsynaptic organization. Additionally, NMDA receptor (NMDAR) activation is critical for maintenance and modification of synapse strength. Specifically, NMDAR activation by spontaneous glutamate release has been shown to mediate some forms of synaptic plasticity, as well as synaptic development. Interestingly, there is evidence that within individual synapses each release mode may be segregated such that postsynaptically there are distinct pools of responsive receptors. In order to examine potential regulators of NMDAR activation due to spontaneous glutamate release in cultured hippocampal neurons, I utilized GCaMP6f imaging at single synapses in concert with confocal and super-resolution imaging. Using these single-spine approaches, I found that Ca2+ entry activated by spontaneous release tends to be carried by GluN2B-NMDARs. The amount of NMDAR activation varies greatly both between synapses and within synapses, and is unrelated to spine and synapse size, but does correlate loosely with synapse distance from the soma. Despite the critical role of spontaneous activation of NMDARs in maintaining synaptic function, their activation seems to be controlled by factors other than synapse size or synapse distance from the soma. It is most likely that NMDAR activation by spontaneous release influenced variability in subsynaptic receptor position, release site position, vesicle content, and channel properties.
  • Effect of Physiologic Bilirubin Concentrations on Apoptosis

    Njonkou Tchoquessi, Rosy Linda; Bearer, Cynthia F. (2019)
    Background: The mechanisms of bilirubin neurotoxicity are poorly understood. We hypothesize that free bilirubin at concentrations found in preterm infants increases neuronal apoptosis. To test this hypothesis, we measured the expression of pro-apoptotic proteins in primary cultures of cerebellar granule neurons exposed to bilirubin using quantitative immunoblotting techniques. Methods: Cerebellar granule neurons were plated on poly-L-Lysine overnight, then treated with human serum albumin combined with bilirubin to produce physiologic concentrations of free bilirubin. Staurosporine was added to some cultures as a positive control. Cell lysates were prepared, and cleaved caspase 3 expression was determined using quantitative immunoblotting techniques. Results: Addition of physiologic concentrations of free bilirubin to cerebellar granule neurons increased the expression of cleaved caspase 3 in a dose dependent manner at 24 hours. Conclusions: Physiologic concentrations of free bilirubin induces apoptosis in cultured rat cerebellar granule neurons.
  • Prescription Medication Adherence among Socioeconomically Diverse Black Men

    DeVance-Wilson, Crystal Lynn; Storr, Carla L. (2019)
    Abstract Background: Non-adherence to prescription medications may at least partially explain high rates of morbidity and mortality from chronic illness among Black men. Black men from lower socioeconomic backgrounds have previously been identified as low adherers but little is known about Black men with adequate incomes and access to healthcare resources. The Ecological Model is used as a framework to examine barriers and facilitators of medication adherence among Black men. Purpose: The purpose of this study is to estimate the prevalence and identify barriers and facilitators to medication adherence among a socioeconomically diverse group of Black men with a range of chronic illnesses. Methods: A cross-sectional study using a 105 item anonymous survey questionnaire was conducted. A convenience sample of 276 Black men (age 35-75 years) was recruited from 15 churches in Baltimore City, and Baltimore, Montgomery and Prince George’s counties. Mann-Whitney U, Kruskall-Wallis and Chi-square analysis were used to examine group differences and multinomial logistic regression provided odds ratio estimates of the association between various factors and low (reference), medium and high medication adherence. Results: Half the sample (49%) were low adherers. Socioeconomic differences in medication adherence were identified by homeownership (X2 = 6.327, p = .042). No statistically significant differences were found for education, employment, income and health insurance coverage. Personal and interpersonal factors found to be associated with medium adherence were coping (AOR=.91, 95% CI=.84-.99), self-efficacy (AOR=6.74, 95% CI=2.79-16.27), income – (low - AOR=10.94, 95% CI=2.42-49.51, middle –AOR=3.34, 95% CI=1.38-8.10), marriage or having a significant other (AOR=5.40, 95% CI=1.83-15.92) and homeownership (AOR=3.37, 95% CI=1.04-10.92). Personal and interpersonal factors found to be associated with high adherence were self-efficacy (AOR=6.63, 95% CI=1.89-23.27), homeownership (AOR=9.32, 95% CI=1.41-61.60), income (low - AOR=8.55, 95% CI=1.31-55.68) and not sharing information with others (AOR=2.89, 95% CI=1.17-7.13). No associations were identified for community, organizational or government/policy level factors. Conclusions: Higher self-efficacy, homeownership and marital status were facilitators and higher coping, higher income and some forms of social support were barriers to medication adherence. This study illuminates opportunities for improving prescription medication education and implementing practice innovations to increase rates of adherence among Black men across the socioeconomic spectrum.
  • Participation and Effectiveness of Worksite Health Promotion Program

    Han, Myeunghee; Doran, Kelly; Storr, Carla L. (2019)
    Background: Worksite Health Promotion Programs (WHPPs) are limited by low participation and engagement. However, little is known about what factors influence participation and the relationship between participation and changes in body weight and composition. Mobile health technology (mHealth) may facilitate participation and engagement in WHPPs as mhealth is not limited by time or location, which are known barriers to participation and engagement. Yet, few studies have examined the use and effectiveness of WHPPs using mHealth interventions that aimed to change body weight and composition. Purpose: To explore the features and effectiveness of WHPPs in previous studies that used mHealth interventions. To identify factors influencing participation and engagement in a WHPP and the relationship between participation and changes in body weight and composition. Methods: A systematic literature review was conducted to explore features of WHPPs using mHealth that aimed to change body weight and composition. A secondary data analysis was conducted using data obtained from participants in the intervention group of a WHPP to identify: 1) factors that influence participation and engagement and 2) the relationship between participation and body weight and composition changes. Results: From the systematic review, 10 out of 12 WHPP studies using mHealth significantly improved body weight and composition. The most commonly used mHealth interventions were providing information, goal setting, and data entry. Based on the secondary data analysis, low levels of stress, anxiety, or high job satisfaction were significantly related to high participation in a WHPP. Significant relationships between participation and body weight and composition changes were not found due to a small sample size. However, this study found that those who reduced five pounds of body weight at six months among overweight or obese participants showed high participation in physical activity and/or diet components of a WHPP. Conclusions: WHPPs using mHealth can significantly improve body weight and composition. Employees’ psychological factors should be considered to increase participation in WHPPs. Further studies with larger sample size are needed to identify the relationship between participation and changes in body weight or body composition.
  • Mothers Engaging in Street-Level Prostitution: A Lived Experience

    Bailey-Kloch, Marie; Shdaimah, Corey S. (2019)
    Abstract Title of Dissertation: Mothers Engaging in Street-Level Prostitution: A Lived Experience Marie G. Bailey-Kloch, Doctor of Philosophy, 2019 Dissertation Directed by Corey Shdaimah, PhD, Professor, School of Social Work This dissertation is a qualitative study with mothers who engage in street-level prostitution. Using a phenomenological approach, this study explored how respondents understand their roles as mothers who engage in street-level prostitution and how these two identities co-exist. The aim of the study was an examination of the way motherhood is understood and explained by the women themselves. The purpose was to understand the way women who engage prostitution construct and define motherhood and how they feel about themselves by eliciting their stories through a phenomenological lens. Six mothers engaging in street-level prostitution were interviewed; a second in-depth semi-structured interview was conducted with five of these. After an analysis employing an interpretive phenomenological approach (IPA), three themes emerged from the data: addiction, perseverance and motherhood. All the respondents met the criteria for the DSM 5 diagnosis of severe substance use disorder. They had the resilience to survive in spite of a lack of resources and enduring trauma. They all believed they had qualities of being a “good mother” even if that meant not living with their children. These findings may help to structure programs that may help influence whether they will seek services to improve the quality of their own lives and the lives of their children. Current programs delivering services to mothers engaged in street-level prostitution, such as substance abuse treatment and diversion programs, do not always recognize the significance to their women participants of being identified as a mother. The insights and perspectives of study respondents regarding their lived experience provides guidance to improve policy and programs that deliver services to mothers who engage in street-level prostitution.
  • Risk of drug overdose death following discharge from a trauma center for an injury

    Greene, Christina Reagan; Smith, Gordon S., M.B., Ch.B., M.P.H.; Albrecht, Jennifer S. (2019)
    Background: Trauma patients have a higher rate of long-term mortality due to natural and external causes, yet drug overdose (OD) death within this population has not been explored previously. Pre-existing behavioral risk factors, such as drug and alcohol use disorders (DUD/AUD), and chronic pain resulting from traumatic injury may increase trauma patient’s risk of subsequent drug overdose death. Objectives: To determine whether trauma patients are at greater risk of drug OD death than the general population and detect whether smoking status or fracture is associated with future drug OD death among surviving trauma patients. Methods: Trauma patients between 18 and 64 years of age who were discharged alive from a Level I Trauma Center between January 1999 and October 2008 were linked to the National Death Index (N=36,288). Patients who were alive at least 30 days after discharge without cancer were included in this study. Trauma patient risk of drug OD death was compared with the age, gender and race adjusted state population using a standardized mortality ratio (SMR) and 95% confidence intervals (CI). Cox proportional hazard regression was used to determine whether current smoking status or lower limb fracture injury were risk factors for drug overdose death factors. Results: Trauma patients had a significantly higher drug overdose mortality rate than the state population [SMR=6.10 (95% CI 5.35-6.93)]. Cox proportional hazard modeling revealed a significant increased risk of drug overdose for current smokers [HR = 1.66 (95% CI 1.25-2.21)]. The effect of smoking was stronger in patients with no DUD/AUD and BAC< 80mg/dL [HR=2.45, 95% CI 1.67-3.57], while smoking was not associated with drug OD death in those with DUD/AUD or BAC≥ 80mg/dL on admission. Patients with lower limb fracture were not at increased risk of drug overdose death compared to those without fracture injuries. Conclusion: Trauma patients have a higher risk of drug OD death than the general population. Smoking is a significant risk factor for drug OD following traumatic injury. Future drug overdose prevention programs should focus efforts on reducing drug overdose mortality in trauma patients, particularly those who smoke.
  • The Muscle Xenograft Model of Facioscapulohumeral Muscular Dystrophy: Development, Optimization, and Novel Applications

    Mueller, Amber; Bloch, Robert J.; 0000-0002-2842-1072 (2019)
    Aberrant expression of DUX4 in human muscle causes Facioscapulohumeral Muscular dystrophy (FSHD) which affects about 1 in 8,333 individuals worldwide, yet the mechanism by which DUX4 causes muscle wasting is unknown. The DUX4 gene is unique to humans and transgenic animal models have largely failed to exhibit the dystrophic phenotype and endogenous molecular changes characteristic of FSHD. Therefore, studies of DUX4 signaling in human muscle have been limited to patient biopsies and cultures of myogenic cells in vitro. There are no therapies that target the mechanism of disease, thus there is a pressing need for studies of DUX4 in mature human muscle. We have developed a method to xenograft human-derived muscle precursor cells, isolated from patients with FSHD and controls, into the tibialis anterior of immune-deficient mice to form xenografts of pure human muscle tissue. The FSHD xenografts are robust, mature, and well organized. Human myofibers are innervated and associate with human satellite cells, making the xenografts structurally comparable to intact human skeletal muscle. The FSHD but not control xenografts express DUX4 and DUX4 gene targets and have 4q35 methylation profiles typical of FSHD. The FSHD grafts also display a novel biomarker of FSHD, SLC34A2, measurable by immunofluorescence, which will provide a quantifiable metric for future therapeutic studies. We have described several modifications to the engraftment strategy that can be used to answer complex mechanistic and functional questions regarding the FSHD pathophysiology. Finally, we report promising data from a collaborative study with Fulcrum Therapeutics in which we were able to repress the DUX4-signaling pathway by administering a targeted small molecule therapy to FSHD grafts. Ours is the first scalable and reproducible in vivo model of FSHD muscle. Future studies will include those aimed at continuing to delineate the molecular pathogenesis of FSHD, performing functional tests to define the pathophysiology of FSHD, and testing new and exciting therapeutic strategies aimed at reducing the DUX4 program in human FSHD xenografts.
  • Multiple Challenges in Kinship Families: How Are They Associated with Children’s Behavioral Health in Kinship Care?

    Xu, Yanfeng; Bright, Charlotte Lyn (2019)
    The use of kinship care has increased in the United States. This dissertation, comprised of three papers, aims to understand multiple challenges in kinship care and their associations with children’s behavioral health using data from the second National Survey of Child and Adolescent Well-being (NSCAW II). Paper 1 developed a new kinship typology based on financial assistance and examined factors associated with receiving Temporary Assistance for Needy Families (TANF) and foster care payments. Results from logistic regression models showed that child maltreatment, children’s externalizing problems, and receiving social services were significantly associated with receiving foster care payments. Living in poverty and a single-adult household were associated with receiving TANF. The results of paper 1 imply that child welfare workers need to increase kinship caregivers’ awareness of financial resources and to make the right resources accessible for them. Paper 2 examined longitudinal relations among economic hardship, economic pressure, TANF, foster care payments, and children’s behavioral problems in kinship care and non-relative foster care. Results of multi-level mixed-effects generalized linear models indicated that economic pressure was associated with children’s internalizing and externalizing problems, as was receiving TANF. Receiving foster care payments was associated with lower externalizing problems. Significant interaction terms showed that foster care payments had positive effects on children’s behavioral health among families without economic hardship and families with economic pressure. The results of paper 2 imply that assessing caregivers’ subjective economic experiences is important to promoting child wellbeing. Findings point to the hardships of families that receive TANF and suggest providing financial and non-financial services to these families. Paper 3 examined the association between neighborhood disorder and children’s behavioral problems and tested the mediating role of social support and the moderating role of race/ethnicity. Results of moderated mediation regression models showed that neighborhood disorder was associated with lower social support, while more social support predicted lower children’s internalizing and externalizing problems. Social support mediated the relation between neighborhood disorder and children’s behavioral problems, but race/ethnicity did not significantly moderate the pathways. The findings of paper 3 imply that interventions are needed to enhance kinship caregivers’ social support and neighborhood quality.
  • Molecular Mechanisms of Enzymes in Infection and Immunity

    Klontz, Erik; Sundberg, Eric J. (2019)
    Enzymes are biological catalysts that enable life by accelerating specific reactions. As new infectious diseases are discovered, the enzymes produced by these organisms require characterization. In some cases, they can be inhibited to prevent disease; in other cases, they can be coopted or altered to serve as diagnostic or therapeutic tools. In this work, we explore the mechanisms of several enzymes involved in infection and immunity. In the first major theme, we characterize the mechanisms of fosfomycin resistance proteins from Escherichia coli (FosA3) and Klebsiella pneumoniae (FosAKP), which degrade the antibiotic fosfomycin. Although the active sites of FosA enzymes are well conserved, differences in activity between enzymes may be due to the presence of an allosteric site at the dimer interface of these enzymes. We solved crystal structures with a novel small molecule FosA inhibitor, termed ANY1, which binds with high affinity to the active site and acts as a competitive inhibitor of fosfomycin binding. By inhibiting FosA, ANY1 potentiates the effects of fosfomycin in several priority Gram-negative pathogens, and may serve as a suitable lead candidate for structure-guided drug design and pre-clinical development. In the second major theme, we describe the mechanisms of enzymes with activity on the carbohydrates of IgG antibodies. EndoS and EndoS2 are enzymes produced by Streptococcus pyogenes, which remove the conserved glycan on Asn297 of IgG to evade the host immune system. We discovered that these enzymes share a conserved mechanism of substrate recognition, binding primarily to the core and α(1,3) antenna of the IgG glycan. EndoS2 recognizes a more diverse set of glycans through differences in the both the active site and a coevolved carbohydrate binding module. We then describe the structure and function of AlfC, an α(1,6)-specific fucosidase from Lactobacillus casei with activity on the core fucose of antibodies. We identified D200 and D242 as the most likely catalytic residues, and provide a structural basis for the remarkable specificity of this enzyme and transfucosidase mutants. Finally, we describe a novel application for these carbohydrate-active enzymes in the directed evolution of antibodies based on yeast display.
  • Health Savings Account Effects on Health and Debt

    Hageman, Sally; Shaw, Terry V. (2019)
    Title of Dissertation: Health Savings Account Effects on Health and Debt Sally Anne Hageman, Doctor of Philosophy, 2019 Dissertation Directed by: Terry Shaw, Ph.D. More than a decade ago Health Savings Accounts (HSAs) were deemed contrary to social work values and practice (Gorin, 2006). More recent research, however, demonstrated HSAs may help individuals’ access financial resources when encountering financial barriers (Hageman & St. George, 2019). To further examine the potential of HSAs, this study examines HSA effects on health and debt outcomes. Applying the framework of the social determinants of health (Dahlgren & Whitehead, 1991) and the health lifestyles theory (Cockerham, 2005), a subset of 12,686 respondents from three years (2010, 2012, and 2014) of secondary quantitative data from the National Longitudinal Surveys of Youth (NLSY) was drawn. The sample included respondents who answered survey questions about owning an HSA, chronic disease status, health behavior, and health-related debt. Descriptive, bivariate, weighted logistic regression, and generalized estimating equation (GEE) analyses were conducted. Descriptive analyses indicated about 47% of HSA owners were male, 64% were Non-Black/Non-Hispanic race/ethnicity, with an average age of 53.34 (SD=2.26) years old, 99% owned their home, and had an average income of $126,853 (SD=$122,994). About 75% of HSA owners reported they did not have a chronic disease and 70% reported they did not have health-related debt. Weighted logistic regression was conducted to determine if Chronic Disease status was associated with HSA ownership status. Results indicated Chronic Disease status (p=.88) was not significantly associated with owning an HSA. GEE was conducted to determine whether HSA ownership status was associated with respondent debt. Results of the GEE analysis indicated HSA ownership status (p=.76) was not significantly associated with reporting Debt.
  • Functional characterization of Myosin Binding Protein-C slow in health and disease

    Geist Hauserman, Janelle; Kontrogianni-Konstantopoulos, Aikaterini (2019)
    Myosin Binding Protein-C (MyBP-C) comprises a family of proteins with structural and regulatory roles in muscle. There are three MyBP-C isoforms in the family, encoded by different genes. Although the isoforms share significant structural and sequence homology, slow skeletal MyBP-C (sMyBP-C), encoded by MYBPC1, is unique as it is heavily spliced in both the NH2 and COOH-termini. To study the role of sMyBP-C in healthy, adult skeletal muscles, in vivo gene transfer and CRISPR plasmids were used to knock down sMyBP-C. Decreased sMyBP-C levels resulted in significantly decreased levels of thick, but not thin, filament proteins. The reduced levels of thick filament proteins were accompanied by disorganized A- and M-bands. Moreover, examination of the contractile activity of treated muscles demonstrated that downregulation of sMyBP-C resulted in significantly decreased force production and velocities of contraction and relaxation. In addition to the extensive exon shuffling that takes place in the NH2-terminus of sMyBP-C, it also undergoes PKA and PKC mediated phosphorylation within two motifs, which flank the first Ig domain of the protein. Recombinant NH2-terminal sMyBP-C phosphomimetic peptides were tested in co-sedimentation and in vitro motility assays, indicating that phosphorylation of sMyBP-C variants regulates actomyosin binding and sliding velocity. Mutations in MYBPC1 have been implicated in the development of distal arthrogryposis, while four recently discovered mutations (Y247H, E248K, L259P, and L263R) co-segregate with the development of a new myopathy characterized by muscle weakness, hypotonia, skeletal deformities, and tremor. In vitro studies and computational modeling suggest altered myosin binding and/or protein instability for the four mutations. Further in vivo evaluation of the E248K mutation in a heterozygous knock-in mouse model revealed significant biochemical, morphological, and behavioral deficits compared to wild type littermates. Additionally, functional assessment of heterozygous E248K muscles demonstrated decreased force and power production, as well as decreased cross bridge cycling kinetics, indicating the tremor may begin at the level of the sarcomere. My studies therefore reveal that sMyBP-C has important structural and regulatory roles within the sarcomere, is modulated through phosphorylation, and that novel MYBPC1 mutations lead to the development of myopathy and tremor that is of myogenic origin.
  • Traumatic Brain Injury (TBI) Causes Alterations in Myeloid Cell Function: Role of Sex Differences and Lung Infection on Overall Outcomes following TBI

    Doran, Sarah Jean; Loane, David J.; Faden, A. I.
    Traumatic brain injury (TBI) is a major cause of morbidity and mortality. Males are nearly 3-times more likely to die from brain injury than females. However, the impact of sex differences in relation to clinical outcomes following TBI is conflicting. Recent studies report that men have an increased risk for lung infection after TBI. Importantly, hospitalized severely injured TBI patients have nosocomial infection rates of 50%. Acute-onset pneumonia represents 30-50% of infections after more severe TBI, leading to increased deaths and disability. The goal of this work was to investigate the role of sex differences and lung infection on overall outcomes following TBI. In a well-characterized murine TBI model, there are increased numbers of infiltrating myeloid cells in male brains as compared to females following injury, correlating with poorer neurological outcomes. However, myeloid cells and microglia in male and female animals showed a similar pattern of activation in response to brain injury- including increased pro-inflammatory cytokines (TNF-α, IL-1β), reactive oxygen species (ROS), and greater phagocytic activity. These these findings suggest that sex differences with regard to immune responses after TBI that may impact overall outcomes. We also examined potential bi-directional brain-lung interactions by examining posttraumatic lung infection at 3- or 60-days after injury. Animals subjected to TBI showed increased mortality after infection with Streptococcus pneumoniae Type 3 (Sp) at both 3 and 60 days post-injury. However, mortality was greater with infection at 60 days following TBI and exacerbated brain injury, with increased markers of neuroinflammation including TNF-α, IL-1β, and NADPH oxidase 2 (NOX2) in the injured cortex. In the lung, TBI followed by infection resulted increased bacterial burden and pathology. Analysis of Ly6C+ infiltrating monocytes in the lungs of mice infected with Sp 3 days post-injury demonstrated that these cells were less able to produce TNF-α, ROS, and IL-1β in response to infection. In contrast, lung-infiltrating Ly6C+ monocytes in mice subjected to infection 60 days post-TBI produced twice as much IL-1β and 50% more ROS as Ly6C+ monocytes from Sham-infected mice. These data show that TBI causes immune alterations, both acutely and chronically, that may contribute to susceptibility to infection.
  • Molecular level studies of the impact of poly (oxonorbornenes) on D. rerio. embryos

    Klutts, Jennifer N.; Rosenzweig, Zeev (2019)
    Poly (oxonorbornenes) (PONs) are amphiphilic cationic polymers that possess antimicrobial properties. Cationic polymers are proposed as an alternative to antimicrobial peptides and it is important to assess their impact on organisms. The two side chains of PONs that are responsible for these properties are a hydrophobic alkyl and a charged amine. In this study, we investigated how changing the amine/alkyl ratio and polymer length affects the activity of PONs on the model vertebrate organism, D. rerio. (zebrafish). Zebrafish embryo toxicity test were used to elucidate the LC50 of PONs. Whole-mount immunofluorescence with caspase-3 was used to analyze apoptotic cells. We hypothesize that PONs would interact with the cell membranes of embryos to induce toxicity and the level of toxicity would depend on the molecular structure of PONs. Our results indicate that increasing the hydrophobicity and polymer length decreases the viability of the embryos and number apoptotic cells in the embryos.
  • Advancing Drug and Biomaterial Design with Constant pH Molecular Dynamics Simulations

    Tsai, Cheng-chieh; Shen, Jana (2019)
    Molecular dynamics (MD) simulation is a valuable tool for investigating motions of macromolecular systems; however, solution pH, a critical factor for biological and chemical processes, is neglected in conventional MD simulations. To address this weakness, our group developed various continuous constant pH molecular dynamic (CpHMD) tools. In this dissertation, applications and new protocols that utilize CpHMD for drug and biomaterial design are presented. β-secretase 1 (BACE1, implicated in Alzheimers disease) and Src kinase (implicated in cancer) were utilized as model systems for drug design applications. In chapter 2, we applied CpHMD to understand the binding of BACE1 with two small-molecular inhibitors. We discovered that, despite the structural similarity of the two inhibitors, the titration behavior of the protein active site differs and this difference dramatically impacts the protein-ligand interactions and consequently the inhibitor affinity. Further, we tested a new protocol that combines CpHMD titration with free energy simulations to construct the pH-dependent binding free energy profiles. The resulting data showed excellent agreement with experiment and identified one potential allosteric site in BACE1. Next, in chapter 3, we simulated Src kinase to test the capability of CpHMD tostudy kinases. Starting from the crystal structure of the inactive Src, CpHMD can capture the conformational activation along the major inactive states without introducing any biasing potential or mutation. Starting from chapter 4, we studied the chitosan-based hydrogel systems to explore the detailed molecular mechanisms that give rise to macroscopic materials properties. We examined the flexibility of chitosan chains under different environmental conditions such as pH and salt concentration. Simulation data revealed that in addition to electrostatic screening, salt ions enhance the chain flexibility by interrupting the intra-molecular hydrogen bonds and thereby shifting the conformational populations between extended and bent states. In chapter 5, the atomic-level mechanism of pH-responsive chitosan-based hydrogels with switchable mechanical properties was investigated. Our data suggested that the electrostatic crosslinks are formed through the pH-dependent salt-bridge interactions between the chitosan glucosamines and surfactant headgroups. The pKa difference between the chitosan crystallite and the surfactant-bound chitosan is a key for the persistent but erasable gradient in the structural and mechanical properties between the two crosslinked regions. In summary, my work provids insights that will contribute to drug and biomaterial design and highlights the usefulness of CpHMD in these fields.
  • Abutment Material Affects the Attachment of Co-cultured Fibroblasts and Keratinocytes

    Tibbs, Maria; Saito, Hanae (2019)
    Creating a stronger transmucosal seal around the implant abutment may help prevent epithelial downgrowth and resultant crestal bone loss. Most studies focus on titanium and zirconium, but provisional restorations are gaining popularity and these materials require further study. Previous in vitro models utilize a monoculture technique to understand cell behavior, which makes direct intercellular comparisons difficult. Our first aim was to develop a co-culture of human gingival fibroblasts and human oral keratinocytes. Then, cell attachment, proliferation, and migration across six commercially available abutment materials was ascertained and comparisons drawn. Discs made of smooth titanium, (control), rough titanium, CAD/CAM poly (methylmethacrylate), poly ether etherketone, smooth zirconium, and rough zirconium were chosen. Preliminary results indicate that at various time points, significant differences in fibroblast and keratinocyte proliferation and attachment exist among abutment materials.
  • Temporary anchorage devices for ridge preservation after extraction

    Joseph, Dr. Surya Elizabeth; Oh, Se-Lim (2019)
    The objective of this study is to investigate effects of transcortical mini-screws placed in the buccal plate of the extraction socket following tooth extraction in human subjects compared to untreated sockets. Patients planned for extraction of two maxillary premolars were recruited. One mini-screw was placed in the buccal plate of the extraction side on the experimental side. The contralateral extraction side was left untreated as the control side. Intraoral digital scans and clinical photographs were obtained at baseline, 4 months, and 8 months. CBCTs were exposed after the extraction and before mini-screw placement and at 8 months. A considerable decrease in ridge width was observed in all three subjects at experimental and control sides. However, the experimental sides exhibited less bone loss compared to the control sides in two subjects. Transcortical mini-screw placement in the buccal plate might reduce dimensional changes at the extraction side.
  • Developing a patient-driven cost-effectiveness analysis of pharmacological treatments for patients with chronic hepatitis C

    Mattingly II, T. Joseph; Mullins, C. Daniel; 0000-0001-7786-5780 (2019)
    Background: Innovations in hepatitis C virus (HCV) drug therapy included in comparative clinical effectiveness evaluations focus on sustained virologic response (SVR) without consideration of socioeconomic or psychological outcomes. This study aimed to identify and prioritize variables important to patients and determine the impact of patient-centered parameters on the cost effectiveness of HCV treatments. Methods: An individual-based state-transition model was developed with the guidance of a patient-centered multi-stakeholder advisory board and patient-only Delphi panel. The model was used to perform a patient-driven cost-effectiveness analysis (CEA) of direct acting antivirals (DAAs) over 10 and 20 year time horizons from both health sector and societal perspectives. The patient-centered model and CEA results were then compared with recently published HCV CEAs. Results: Patients identified treatment effectiveness, longer life, fear of complications, financial issues, quality of life, and impact on society as important factors to include. Fear of harming others was considered more important than physical symptoms in terms of patient-reported problems caused by HCV. Total infected life-years (ILYs) and work days missed were reduced in the treatment group for both 10 and 20 year health sector models in addition to quality-adjusted life-year gains. Compared to no treatment, the incremental cost-effectiveness ratio for treatment would be $3,464/ILYs avoided, $715/work day missed, and $39,086/QALY gained. When costs of absenteeism, presenteeism, and patient/caregiver time were included, the DAA intervention was cost-saving at both 10 and 20 years. Very few traditional economic models for HCV treatments attempt to capture the indirect and non-medical costs or outcomes that may impact HCV patients. Conclusions: Treatment was cost-effective from a health sector perspective and cost-saving when including non-health costs such as patient/caregiver time and productivity. Compared to published HCV CEAs that focused mainly on SVR, our patient-centered CEA provides results that reflect the outcomes of interest informed by direct patient engagement.

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