The University of Maryland Graduate School Baltimore (UMGSB) offers 27 master's and doctoral programs in health, physical, biomedical, medical, and social sciences.

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  • Identification of Actionable Variants, Reproductive Health and Other Health Outcomes in a Founder Population

    Lynch, Megan Therese; Mitchell, Braxton D.; 0000-0003-4805-9610 (2021)
    Genetically isolated populations that have arisen due to recent bottleneck events have reduced genetic variation that reflect the common set of founders. Many genetic variants that are rare in the general population drift to a high frequency in isolate populations, including some variants causing rare Mendelian diseases. The Old Order Amish of Lancaster County, PA, are a population isolate that are largely descendants of <200 of the original settlers. The unique genetic, cultural, and environmental homogeneity of the Amish is reinforced by the cultural proclivity to marry within the community. The overall theme of this thesis is to evaluate the impact of limited genetic diversity on reproductive outcomes and other traits of biomedical importance. This theme is addressed through three complementary sub-studies, each considering a different aspect of the impact of genetic homogeneity on the health of the Amish. In the first sub-study, seven pathogenic/likely pathogenic (P/LP) variants were identified within genes deemed clinically actionable by the American College of Medical Genetics and Genomics (ACMG) or Geisinger’s My Code Health Initiative. In total, 14.7% of Lancaster Amish individuals carry at least one of these variants, largely explained by the 13% who harbor a copy of a single variant in APOB. The Amish harbor fewer actionable variants compared to similarly characterized non-founder populations but have a higher frequency of each variant identified. The second sub-study assessed the burden of parental relatedness on reproductive health. Amish couples who were both heterozygous carriers of a highly penetrant P/LP variant experienced fewer number of miscarriages than non-carrier couples from the same Amish community. In addition, overall genetic relatedness between spouses was highly correlated with number of live births (p <0.0001), pregnancies (p <0.0001), and stillbirths (p=0.03). The third sub-study evaluated autozygosity (FROH), the portion of the genome that is homozygous by descent. Measurements of genome-wide and regional FROH were used as the primary predictors of trait variation in association analysis of 96 traits. No associations were identified when assessing genome-wide autozygosity measurements, but regional FROH estimation revealed two regions in which increased autozygosity was associated with increased trait values.
  • Behavioral and Social Support Effects on Daily Oral Pre-exposure Prophylaxis use among Men who have sex with Men in Nigeria

    Adeyemi, Olusegun Adewale; Charurat, Manhattan; Nowak, Rebecca G; 0000-0002-2051-002X (2021)
    Introduction: HIV incidence among men who have sex with men (MSM) in Nigeria was 5.8-23.1/100 person years (PY) in 2019, exceeding the ≥ 3/100 PY recommended by the WHO for initiation of HIV pre exposure prophylaxis (PrEP). Objectives: To estimate the correlation between self-reported PrEP adherence (SRPA) and PrEP biomarkers (assay), to assess the association between perceived social support (SS) with protective PrEP adherence (PA), and to estimate the effect of PrEP use on behavioral outcomes. Methods: In this open-label, one-year follow-up, prospective cohort study, MSM living in Abuja were introduced to PrEP in clinic or community based setting for five scheduled visits (baseline, months 1, 3, 6, and 9). Clinical information and sexually transmitted infection (STI) samples were collected at each study visit. PrEP biomarker assays were conducted at month 3 and 9. The correlation between SRPA and assay results was estimated with Spearman’s correlation. Logistic regression estimated adjusted odds ratio (aOR) between SS (informational, instrumental and informational) and PA. A conditional logistic regression estimated aOR of STIs (Rectal and urethral Gonorrhea [NG] and Chlamydia) of behavioral outcomes (Condomless anal intercourse [CAI] and concurrent sex partnerships) comparing pre-PrEP versus Post-PrEP period. Results: Of 400 that initiated PrEP between April 2018 and May 2019, 219 had ≥1 assay, with median age 23 (interquartile range 20-27) years. Of this 219, sixty-six (30%, 95% CI: [0.24, 0.36]) had ≥1 PA. A total of 206 were eligible for pre-post-PrEP period analysis. In multivariable analysis, participants with perceived emotional SS had 42% increased odds (aOR: 1.42, 95% CI: [1.00, 2.00]) of PA. In the post-PrEP period, compared with pre-PrEP period, participants had 3.5 times increased odds (OR: 3.53, 95% CI: 1.10, 11.35) and 51% decreased odds (aOR: 0.49, 95% CI: 0.28, 0.84) of rectal NG diagnosis and reporting CAI, respectively, but no significant changes in prevalence of all STIs. Conclusion: There was no association between SRPA and assay; perceived emotional SS was a facilitator of PA. We demonstrated trends of PrEP associated sexual behavioral modifications but further studies are required. Our study findings have implications for PrEP implementation in Nigeria and similar settings.
  • Subsynaptic positioning of AMPARs by LRRTM2 controls synaptic strength

    Ramsey, Austin M.; Blanpied, Thomas A.; 0000-0002-5567-2619 (2021)
    Recent evidence suggests that the nanoscale organization of proteins within synapses may control the strength of communication between neurons in the brain. The unique subsynaptic distribution of glutamate receptors, which cluster in nano-alignment with presynaptic sites of glutamate release, supports this idea. However, testing it has been difficult because mechanisms controlling this subsynaptic organization remain unknown. Reasoning that transcellular interactions could influence AMPAR positioning, we targeted a key transsynaptic adhesion molecule implicated in controlling AMPAR number at synapses, LRRTM2, using engineered, rapid proteolysis. Severing the LRRTM2 extracellular domain led quickly to nanoscale de-clustering of AMPARs away from release sites, not prompting their escape from synapses until much later. This rapid remodeling of AMPAR position produced significant deficits in evoked, but not spontaneous, postsynaptic receptor activation. These results dissociate receptor number within synapses from their nano-positioning in determination of synaptic function and support the novel concept that adhesion molecules acutely position AMPA receptors to dynamically control synaptic strength.
  • Patterns, Factors and Outcomes associated with Gabapentin use in Combination with Opioids and Benzodiazepines among Social Security Disability Insurance (SSDI)-eligible Medicare Beneficiaries

    Olopoenia, Abisola; Simoni-Wastila, Linda (2021)
    Background: Little is known about the patterns, factors, and public health outcomes associated with concurrent utilization of gabapentin, opioids, and benzodiazepines (GABA+OP+BZD) Objective: To examine the patterns, factors, and public health outcomes associated with concurrent utilization of GABA+OP+BZD among Social Security Disability Insurance (SSDI) eligible beneficiaries. Methods: Using a 5% sample of 2013-2016 Medicare data, we utilized a retrospective cohort design to examine the following patterns of concurrent utilization: monotherapy, dual therapy, tri-therapy, switching, augmentation, discontinuation, and continuation. Similarly, a retrospective cohort design was utilized to examine the sociodemographic and clinical factors associated with the longest concurrent medication utilization episode, defined based on the overlap of prescriptions for GABA+OP+BZD. We used a nested case control design to examine the association between concurrent utilization of GABA+OP+BZD and adverse outcomes (respiratory depression, substance and opioid related overdose, and adverse drug-related events) among disabled beneficiaries with acute pain [AP], chronic pain [CP], and mental health conditions [MH]. Results: Among disabled beneficiaries, gabapentin initiators were significantly more likely to become dual and tri-therapy users (p<0.01) and to augment therapy (50.1%) when compared to opioid (28.7%) and benzodiazepine (38.7%) users; the majority augmented within 2-months after initiating therapy. Back pain [AOR(95%CI): 1.23(1.07-1.41)], chronic pain [1.27 (1.07-1.51)], mental health [1.16 (1.02-1.33)], opioid dose [1.05 (1.03-1.06)] and duration [1.07 (1.06-1.07)], and benzodiazepine duration [1.06 (1.05-1.06)] were positive predictors of having longest concurrent use involving GABA+OP+BZD. Concurrent GABA+OP+BZD use was associated with increased odds of respiratory depression [AP: 1.35 (1.19-1.52), CP:1.24 (1.11-1.38) and MH: 1.16 (1.02-1.32)], opioid related overdose [AP: 1.43 (1.04-1.98), CP: 1.47 (1.07-2.00) and MH: 1.44 (1.04-2.00)], substance related overdose[AP: 1.77 (1.26-2.50), CP: 1.70 (1.24-2.34) and MH: 1.92 (1.31-2.82)] and adverse drug related events[AP: 1.36 (1.22-1.50), CP: 1.23 (1.10-1.36) and MH: 1.15 (1.02-1.30)]. Conclusion: Our study provides the first evidence of patterns, factors, and outcomes associated with concurrent utilization of GABA+OP+BZD. Given noted adverse outcomes associated with GABA+OP+BZD, it is imperative that the benefits and risks of co-prescribing these medications be examined comprehensively, especially for those at the greatest risk of being prescribed these medications.
  • Exploiting Vulnerabilities in Cancers with Activated Extracellular Signal-Regulated Kinase (ERK1/2)

    Martinez, Ramon; Shapiro, Paul, Ph.D.; 0000-0002-0050-3172 (2021)
    Constitutively active extracellular signal–regulated kinase (ERK) 1/2 signaling promotes cancer cell proliferation and survival. ERK1/2 pathway inhibitors are important therapies for treating many cancers, however, acquired resistance to most protein kinase inhibitors limit their ability to provide durable responses. Few studies have looked at the adaptive proteome responses of BRAF/MEK dual inhibitor resistant cells, and fewer still have established the utility of allosteric inhibitors targeting the ERK2 protein. The overall goal of the current study was to identify signaling mechanisms of therapeutic resistance and further investigate a previously identified inhibitor of melanoma cell growth with putative activity with the protein ERK2. To test this, we hypothesize that vulnerable targets can be identified for therapeutic intervention, and test if alternative inhibitors exhibit clinical potential for melanoma treatment in two specific aims. In Aim 1, we characterized the global protein changes happening in constitutively-activeERK1/2 melanoma cells models that developed resistance to BRAF (PLX4032) and MEK1/2 (AZD6244) inhibitors using mass spectrometry. We additionally identified putative targets for treatment and analyzed the potential for a metabolic inhibitor, niclosamide. In Aim 2, studies were focused on elucidating the structure-activity relationship and binding mechanism of a ERK2-specific inhibitor developed in house, SF-3-030. We identified chemical features required for biologic activity and global effects on gene and protein levels in A375 melanoma cells containing mutant BRAF(V600E). We then identified the mechanism of action of the inhibitor in preventing melanoma growth using mass spectrometry analysis. Overall, these studies help to elucidate how cells overcome currently used clinical therapies, what vulnerable markers can be identified and used for therapeutic intervention, and that inhibitors alternative to the clinical standard can show potential for melanoma treatment.
  • Finding Islands of Structure in a Sea of Variance: Dimensions of Covariance Between Migraine Symptoms and Brain Connectivity

    Krimmel, Samuel R; Seminowicz, David A.; 0000-0002-5198-1545 (2021)
    Migraine is a heterogeneous disorder with variable symptoms and responsiveness to therapy. Current attempts to capture migraine variability through migraine subtyping are not informed by biology, ignore many migraine symptoms, and are not predictive of treatment responses. Taking advantage of neural network organization captured with resting-state functional connectivity (RSFC) and advanced statistical analysis, sophisticated symptom-brain mapping can now be performed. In aim one, I use a multivariate approach to relate clinical variability in migraine to RSFC, and find three dimensions of covariance between symptoms and the brain. Additionally, I show that the current subtyping of migraine does not adequately capture clinical heterogeneity. Instead, using the three identified dimensions of covariance, biotyping of migraine can be performed that does a better job of capturing migraine variability than the current field norm. In aim two I examine how RSFC can help to predict variability in migraine patient response to the mind-body therapy Mindfulness-Based Stress Reduction (MBSR), in the hopes of developing precision medicine for migraine. Finally, in aim three, I examine the mechanisms of MBSR by analyzing how MBSR changes functional connectivity to reduce the frequency of headaches. These findings suggest that novel approaches can better capture migraine variability, paving the way for the development of personalized treatment of migraine.
  • Association of Patient Cost Sharing and Area Deprivation with Multiple Myeloma Treatment Receipt and Outcomes

    Hong, Yoon Duk; Slejko, Julia F; 0000-0002-9548-5770 (2021)
    Introduction: Advances in multiple myeloma (MM) treatment have improved survival, but there are increased concerns about treatment affordability and access. This study assessed 1) how cost-sharing assistance and area deprivation affect treatment receipt, 2) changes in the patient cost responsibility and disparities in treatment over time, and 3) how the low-income subsidy (LIS), which lowers Part D cost sharing, and area deprivation affect treatment access and survival. Methods: Using the Surveillance, Epidemiology, and End Results-Medicare database, we identified patients diagnosed with MM. The effect of cost-sharing assistance and area deprivation on treatment was estimated using multilevel logistic regression. We estimated the monthly incremental patient cost responsibility among MM patients compared to non-cancer controls and examined changes over time (2007-2011, 2012-2016). The effect of diagnosis period and area deprivation on treatment was estimated using multilevel logistic regression. The association between LIS, area deprivation, and mortality was estimated from a mixed-effects Cox proportional hazards model. We assessed whether treatment mediates the association between LIS and mortality. Results: Individuals receiving Medicare Parts A, B and D cost-sharing assistance had higher odds of receiving treatment compared with non-recipients (OR=1.21; 95%CI: 1.01–1.45). Living in the most deprived area (Quintile 5) was associated with lower odds of receiving treatment compared with the least deprived area (Quintile 1; OR=0.81; 95%CI: 0.65–0.99), but there was no difference in the other quintiles. The difference in the estimated monthly incremental patient cost responsibility between 2012-2015 and 2007-2011 was $58 [average marginal cost; 95%CI: $12–$105]). The difference in the likelihood of any treatment receipt between Quintile 1 and 5 decreased, but the difference in the likelihood of receiving a novel agent-based regimen increased. The mortality hazard was higher for LIS recipients relative to non-recipients in Quintiles 1, 3 and 4 (HR=1.50, 1.38, 1.28; p=0.0001), and there was no difference in the other two quintiles. This association was partially mediated by treatment receipt. Conclusions: The patient cost responsibility for MM care increased over time. The type of cost-sharing assistance and area deprivation affect treatment receipt, although not across all quintiles. LIS receipt did not confer a survival benefit.
  • Mechanisms of Heart Failure Related Fatigue

    Hoch, Christine Renee; Klinedinst, N. Jennifer (2021)
    Background: Fatigue has been reported in 53-100% of patients with heart failure (HF). Fatigue in HF is described as a highly burdensome symptom that has a profoundly negative effect on quality of life and is associated with worsening prognosis and mortality. Despite its prevalence and deleterious outcomes, HF-related fatigue remains poorly understood with limited treatment modalities. Purpose: The purpose of this dissertation was to (1) describe known physiologic, psychologic, and situational correlates of HF-related fatigue, (2) evaluate the contribution of select physiologic variables to HF-related fatigue, and (3) identify correlates of excessive daytime sleepiness (EDS) in chronic stroke survivors as groundwork for future studies examining fatigue in HF. Methods: The first manuscript is a synthesis of the scientific literature on known correlates or mechanisms of HF-related fatigue. The second manuscript uses cross-sectional data from the 2015-2018 National Health and Nutrition Survey (NHANES). A complex sample design was used to assess the contribution of select physiologic variables on HF-related fatigue. Independent t tests and chi-square tests were used to explore differences between fatigued and non-fatigued adults and logistic regression to calculate the odds of having fatigue. Non-parametric correlations and descriptive statistics were used in the third manuscript to describe the relationship of EDS to sleep quality, body mass index (BMI), systemic inflammation, and energy metabolism of platelets in chronic stroke survivors. Results: Correlates of HF-related fatigue include age, sex, dyspnea, pain, disease severity, use of diuretics, volume status, anemia, oxygen uptake, depression, anxiety, perception of symptoms/health, sleep disturbances, poor social support, reduced quality of life. Concepts were grouped into 5 categories: individual, physiologic, psychologic, situational and outcome. Analysis of NHANES data revealed a low serum osmolality was significantly associated with fatigue (χ2 = -2.37, p = .03). Being female was predictive of experiencing fatigue when controlling for age, serum osmolality, serum hemoglobin and the presence of dyspnea (OR 4.68, 95% CI .34 – 2.75). The analysis of the pilot data found EDS in 27.3% of the sample. No statistical correlations were found between EDS, inflammatory markers, energy metabolism of platelets, sleep quality or BMI. A non-significant moderate effect size was noted with IL1-β (rho.42) and TNF-α (rho .35) and EDS. A small effect size was noted with IL-6 and EDS (rho .26). Conclusions: Improving our knowledge of mechanisms of HF-related fatigue will inform strategies to reduce or ameliorate the symptom. Future studies should continue to assess the relationship between serum osmolality, sex hormones and cellular energy metabolism to fatigue in patients with HF.
  • Cue-triggered reward seeking: The role of dopamine and corticotropin releasing factor in the bed nucleus of stria terminalis

    Gyawali, Utsav; Calu, Donna J; 0000-0001-5072-6780 (2021)
    Survival depends on learning associations between reward and reward predictive cues. Cues associated with rewards, however, can also reinforce maladaptive behaviors. Pharmacological inactivation of the bed nucleus of stria terminalis (BNST) reduces cue-induced drug reinstatement. Neural signaling in the BNST underlying cues-maintained motivated behavior remain poorly understood. The overarching objective of this dissertation is to identify the role of key neuromodulators in the BNST during cue-triggered reward seeking. In Chapter 2, I focus on corticotropin releasing factor (CRF) and its contribution in incubation of fentanyl seeking after forced abstinence. I find that antagonizing CRF receptors in the BNST results in reduced incubation of fentanyl craving and encourages disengagement from lever pressing for cues in abstinence. In Chapter 3, I use fiber photometry in combination with the dopamine sensor GRABDA to measure real-time dopamine signals when rats are engaged in a Pavlovian Lever Autoshaping task. I first demonstrate that Pavlovian cue-evoked dorsal BNST GRABDA signals are enhanced in rats that assign incentive motivational properties to reward cues. I next characterize GRABDA signals in reward prediction error, satiety, systemic fentanyl administration, and during responding for fentanyl-associated cues. Collectively, these findings establish a relationship for BNST CRF and dopamine in cue-evoked self-motivated behaviors.
  • A Cluster Analytic Approach to Identify Insomnia Subtypes and Their Relationship with Economic Outcomes

    Gandhi, Aakash Bipin; Onukwugha, Eberechukwu (2021)
    INTRODUCTION: Insomnia is a heterogenous condition with respect to underlying risk factors, presentation of symptoms, comorbidities, disease course, and outcomes. Consequently, individuals with insomnia may also have varying patterns of healthcare resource utilization and costs. However, the impact of insomnia heterogeneity on economic outcomes is not known. METHODS: We used an integrated claims-electronic health records dataset to identify individuals aged 18-64 with insomnia between 2009-2018. A k-modes clustering algorithm with a Jaccard coefficient similarity measure was used to identify clinically relevant insomnia subtypes based on sociodemographic, comorbidity, behavioral, life event, family history, medication use, vital sign, and insomnia symptom-related characteristics. An optimum cluster solution was chosen based on clinical interpretability and significance. Insomnia clusters were compared on baseline characteristics using Chi-square tests. Logistic regression models were used to identify the association between cluster membership and binary outcomes (inpatient hospitalization, emergency department [ED] visits). Generalized linear models were used to assess similar associations with count physician office visits, non-physician outpatient visits, prescription drug fills) and cost outcomes associated with all points of service. RESULTS: A total of 17,124 individuals with insomnia met the study inclusion criteria. The cluster analysis resulted in a five-cluster solution. The clusters were labelled as ‘Insomnia associated with obesity and hypertension’ (28.6%), ‘Insomnia associated with mental health conditions and chronic pain’ (25.4%), ‘Insomnia associated with older age, high comorbidity burden, and fatigue’ (24.6%), ‘Insomnia associated with substance use disorders’ (5.2%), and ‘Insomnia associated with overweight status, alcohol use, and low comorbidity burden’ (16.2%). Relative to the reference cluster ‘Insomnia associated with overweight status, alcohol use, and low comorbidity burden’, individuals in cluster labelled as ‘Insomnia associated with older age, high comorbidity burden, and fatigue’ displayed higher total healthcare costs (cost ratio [CR]: 1.46; 95% CI: 1.32, 1.62) primarily driven by higher inpatient (CR: 1.68; 95% CI: 1.48, 1.91) and prescription drug fill (CR: 1.49; 95% CI: 1.34, 1.65) costs. CONCLUSION: Findings from the present study can help improve our understanding about developmental trajectories for insomnia diagnosis and facilitate the design of tailored interventions that target those at the highest risk for adverse economic consequences.
  • Defining the Role of PARylation on STAT5 Activity in Mutated FLT3-ITD Acute Myeloid Leukemia

    Dellomo, Anna Justine; Rassool, Feyruz V.; 0000-0003-0310-8474 (2021)
    Internal tandem duplications of fms-like tyrosine kinase 3 (FLT3-ITD) in acute myeloid leukemia (AML) contribute to a significantly poorer prognosis by causing constitutive activation of the FLT3 receptor and producing aberrant signaling through signal transducer and activator of transcription 5 (STAT5). STAT5 signaling in this AML subtype and drives cell survival and proliferation. Additionally, our group has previously found that STAT5 signaling directly contributes to the genomic instability of FLT3-ITD AML, making these cancers more susceptible to mutation and the development of resistance to therapy. Due to the critical role of STAT5 in FLT3-ITD AML progression, understanding how this protein is regulated may aid the development of treatment strategies for this disease as well as other STAT5-activated cancers. Poly (ADP-ribose) polymerase 1 (PARP1) is primarily known for its role in DNA repair, but PARP1 can also regulate diverse proteins through its catalytic function of adding poly-ADP-ribosyl groups (PARylating), affecting many other processes. We have previously reported that PARP1 is upregulated in FLT3-ITD AML and contributes to the genomic instability of these cells through upregulation of the highly error-prone DNA repair mechanism, alternative non-homologous end-joining (Alt-NHEJ). In the current study, examination of tyrosine kinase inhibitor (TKI)-resistant FLT3-ITD AML revealed further upregulation of STAT5 and PARP1 protein, indicating highly increased levels of signaling which may represent a therapeutic target. Importantly, examination of the STAT5 protein sequence revealed putative PARylation sites and we now describe a novel binding of PARP1 to STAT5 and direct PARylation of STAT5 in FLT3-ITD AML. Moreover, we demonstrate that PARP1 depletion and inhibition reduces STAT5 protein expression and activity by causing degradation of STAT5 in FLT3-ITD AML cells, suggesting a novel role for PARylation in stabilizing STAT5 protein and potentiating aberrant signaling. Importantly for translational significance, PARP inhibition (PARPi) was cytotoxic in STAT5-activated cancer cells and it was found that PARPi was synergistic with TKI in both TKI-sensitive and -resistant FLT3-ITD AML cells, indicating significant therapeutic potential. Thus, we demonstrate a novel mechanism that may be targeted by PARPi for therapeutic benefit in STAT5-activated leukemias and other cancers.
  • Nanotechnology-Based Dental Materials for Root Caries Management: Design Concepts and Advanced Strategies to Modulate Dysbiotic Patient-derived Oral Biofilms

    Balhaddad, Abdulrahman Abubaker; Melo, Mary Anne; Xu, Huakun H.; 0000-0001-6678-7940 (2021)
    The distinctive challenges associated with root caries demand innovative interventions to preserve the tooth structure and surrounding soft tissues. This dissertation is composed of a set of manuscripts aiming to advance the anti-biofilm approaches to prevent root caries from two perspectives: (i) invasive approach via novel bioactive resin composites, and (ii) non-invasive approach via magnetic field-guided antimicrobial photodynamic therapy (MF-aPDT). The first chapter provided a general introduction concerning the clinical burden of root caries, current treatment modalities, and their limitations. In the second chapter, I provided an overview of contact-killing monomers and bioactive fillers in restorative dentistry. Then, in chapter three, we developed bioactive resin composite formulations containing dimethylaminohexadecyl methacrylate (DMAHDM) antibacterial monomer and 20% nano-sized amorphous calcium phosphate (NACP) and subjected them to a series of mechanical/physical tests and antibacterial assays. We found that the DMAHDM-NACP resin composites were associated with a potent antibacterial action against cariogenic and periodontal biofilms, as 2 to 6-log reduction was observed. Other virulence factors, as lactic acid production, and polysaccharide production, were also reduced. The mechanical properties, physical characteristics, surface features, and polymerization behavior were comparable to the commercial control at baseline testing and after one year of aging. We concluded that the designed bioactive formulations might present a pathway to preven recurrent caries and the onset of periodontal diseases around dental restorations. In chapter four, we reviewed the most recent updates related to the implementation of nanotechnology to enhance antimicrobial photodynamic therapy (aPDT). Then, in chapter five, we investigated the impact of encapsulating superparamagnetic iron oxide nanoparticles (SPIONs) and toluidine blue ortho (TBO) inside a microemulsion, named MagTBO, to enhance the TBO’s penetration and antibacterial action against S. mutans and saliva-derived biofilms. Besides, the ability of magnetic field (MF) navigation to serve as a biofilm penetration strategy was also investigated. The MagTBO microemulsions were synthesized successfully and demonstrated excellent biocompatibility and thermodynamic stabilities. Furthermore, the MagTBO microemulsions demonstrated more remarkable and significant antibacterial action than conventional aPDT, especially when the MF is applied. Thus, this approach can be an adjunctive technique to control dental caries and other oral diseases.
  • Molecular Mechanisms of Intestinal Bile Acid Transport and Immunomodulatory Potential of Bile Acids

    Ayewoh, Ebehiremen; Swaan, Peter W.; 0000-0002-8390-1538 (2021-12)
    Bile acids are catabolic products of cholesterol that play an important role in the digestion of dietary facts, lipid soluble vitamins, and drugs, as well as a role in immune regulation and glucose homeostasis. They function as complex signaling molecules to prevent intracellular accumulation of bile acids and modulate bile acid and cholesterol homeostasis via activation of a nuclear receptor, Farnesoid X receptor (FXR), to repress bile acid uptake transporters and enhance bile acid efflux transporters. The human sodium dependent bile acid transporter (ASBT) is a highly regulated intestinal uptake transporter that acts as the rate limiting step in bile acid transport in the enterohepatic circulation. Targeted ASBT inhibition is currently being investigated for use in cholestasis, hyperlipidemia, chronic idiopathic constipation, and type 2 diabetes. While studies on post-translational modifications (PTMs) have revealed N-linked glycosylation and phosphorylation as regulators of ASBT, ASBT regulation is still poorly understood. The lipid-based PTM, S-acylation, is the reversible addition of an acyl chain, via a labile thioester linkage, onto cysteine residues, thereby increasing the affinity of proteins to cellular membranes. In this work, we show that human ASBT is S-acylated and that S-acylation is vital for ASBT function, cell surface expression, substrate transport kinetics, and protein stability. Screening of cysteine mutants in and or near transmembrane domains, some of which are exposed to the cytosol, confirmed Cys314 to be the predominate S-acylated residue. Mutation of cytosolic tyrosine residues resulted in decreased ASBT S-acylation suggestive of crosstalk between both PTMs and the existence of multiple PTM-based proteoforms. Finally, we investigate functional implications of the potential acyl transferases responsible for ASBT acylation. Overall, we have provided valuable insight on human ASBT regulation and highlighted the necessity for further investigation of the impact of PTM proteoform in drug development. While understanding ASBT regulation is vital in addressing intestinal and hepatobiliary disease states, the extent as to which its substrate, bile acids, play in other molecular processes is important in fully understanding the broader relevance of intestinal bile acid transport and bile acid signaling. Bile acids have emerged as complex signaling molecules in glucose homeostasis and immune regulation where they can activate specific receptors to increase insulin secretion and exert anti-inflammatory responses from mucosal immune cells, respectively. Using immunological approaches, we provide preliminary evidence and scientific perspective on the use of bile acids in nanoformulation that aims to exploit the immunomodulatory potential of bile acids.
  • Analysis of Sling Wear Time after Shoulder Surgery

    Gilotra, Mohit N; Terrin, Michael L. (2021)
    Introduction: Sling wear is a component of rehabilitation after shoulder surgery. The purposes of this study were to observe the predictors of sling wear and to determine if a threshold of sling compliance improved patient-reported outcomes. Methods: We performed a prospective observational study of 105 postoperative patients fitted with temperature-sensing slings to monitor adherence. Demographic factors were analyzed as predictors of sling wear. The relationship of actual sling wear with patient reported and radiographic outcome was explored. Results: There was a weak correlation between patient reported and actual sling wear time. Females and patients with lower BMI were most likely to be 80% adherent with sling wear and exhibited better patient reported outcomes but no difference in radiographic failures. Conclusion: There is an association between high adherence and patient reported outcome. Further studies will elicit the social mediators of postoperative sling behavior and treatments to improve patient adherence and outcome.
  • Novel Dental Nanocomposites with Low-Shrinkage-Stress, Ion Recharge, Antibacterial and Remineralization Capabilities to Protect Tooth Structures

    Bhadila, Ghalia Yaseen; Xu, Huakun H.; Weir, Michael D.; 0000-0002-7361-9221 (2021)
    The objectives of this dissertation were to: (1) investigate a bioactive nanocomposite with strong antibacterial and ion-recharge capabilities containing dimethylaminododecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and evaluate long-term Ca and P ion recharge by testing for 12 cycles of recharge and release; (2) develop a low-shrinkage-stress (LSS) nanocomposite with antibacterial and remineralization capabilities through the incorporation of DMAHDM and NACP to reduce marginal enamel and dentin demineralization under recurrent caries biofilm-model; (3) investigate the effects of the new composite on biofilm inhibition, mechanical properties, shrinkage stress, degree of conversion, and Ca and P ion releases; and (4) investigate the cytotoxicity of the new LSS composite and its monomers in vitro. For the antibacterial and rechargeable nanocomposite, biofilm lactic acid and colony-forming units (CFU) were measured. Ion recharge was tested for 12 cycles. For the LSS antibacterial and remineralizing nanocomposite, mechanical properties, shrinkage stress, and degree of conversion were evaluated. The growth of Streptococcus mutans and multi-species salivary biofilms was assessed using biofilm CFU, lactic acid production, and confocal laser scanning microscopy. Ca and P ion releases, and human gingival fibroblasts cytotoxicity were measured. The bioactive rechargeable nanocomposite reduced biofilm acid production and viability. High levels of ion releases were maintained throughout 12 cycles of recharge, maintaining steady-state releases without reduction in 6 months, representing long-term remineralization potential. The LSS composite with DMAHDM and NACP had flexural strength matching that of a commercial control composite. The bioactive low-shrinkage-stress composite substantially reduced the biofilm CFU and lactic acid production compared to control composite. The bioactive LSS composite exhibited no significant difference in antibacterial performance before and after three months of aging, demonstrating long-term antibacterial activity. The shrinkage stress of the bioactive low-shrinkage-stress nanocomposite was 36% lower than that of traditional control composite, with similar degrees of conversion. The new bioactive nanocomposite had a satisfactorily low cytotoxic effect toward human gingival fibroblasts and the new monomers had fibroblast viability similar to that of commercial control. The two developed nanocomposites are promising to inhibit recurrent caries and protect the teeth with an intended application for reducing recurrent caries.
  • Peak Alpha Frequency: Discovery and Validation of a Prolonged Pain Biomarker

    Furman, Andrew J.; Seminowicz, David A. (2021)
    Chronic pain is a pervasive and debilitating disease that afflicts nearly one in five individuals. Given its frustrating treatment resistance, one avenue for combatting chronic pain is to develop interventions that can be used to prevent disease emergence. One barrier to realize these interventions, however, is that it is difficult to identify individuals at high risk for developing chronic pain or to identify those already in the early stages of disease development. Previous work has indicated that Peak Alpha Frequency (PAF), an EEG-derived measure of the frequency element demonstrating maximal power in the 8-12 Hz range, is abnormally slow in cases of chronic pain. This PAF slowness may reflect processes related to ongoing pain or factors that predispose an individual to being highly sensitive to pain, perhaps the best-known risk factor for developing chronic pain. Using experimental models of prolonged pain in healthy individuals, as well as ongoing EEG, the current work tests these two hypotheses and reveals several key findings. First, in support of the hypothesis that PAF reflects risk factors associated with heightened chronic pain risk, PAF recorded during a pain-free state is negatively correlated to pain experienced during a future noxious with slower PAF associated with greater pain sensitivity. Second, the relationship between pain-free PAF and pain sensitivity is reliable and can be observable across multiple models of prolonged pain and at multiple points of time. Third, in support of the hypothesis that PAF slowing is a consequence of ongoing pain, exposure to prolonged pain produces reliable PAF slowing that occurs through focal power reductions in the “fast” 10-12 Hz portion of the Alpha range. This latter finding represents the first mechanistic evidence through which PAF slowing occurs. In total, these findings strongly position PAF for use in the clinic as a diagnostic tool for identifying individuals at high risk for developing chronic pain and for identifying those individuals in the early stages of pain emergence.
  • PGE2 is a Candidate Remodeling Factor of the ASDN

    Zapf, Ava M.; Welling, Paul A. (2021)
    Aberrant activation of WNK-SPAK kinase signaling in the distal convoluted tubule (DCT) causes unbridled activation of the thiazide-sensitive sodium chloride cotransporter, NCC, leading to Familial Hyperkalemic Hypertension (FHHt) in humans. Studies in FHHt mice engineered to constitutively activate SPAK specifically in the DCT (CA-SPAK mice) revealed maladaptive remodeling of the aldosterone sensitive distal nephron (ASDN), characterized by decrease in the potassium excretory channel, ROMK, and ENaC, that contributes to the hyperkalemia. The mechanisms by which NCC activation in DCT promotes remodeling of CNT are unknown, but paracrine communication and reduced salt delivery to the ASDN have been suspected. Here we explore the involvement of prostaglandin E2 (PGE2). We found that PGE2 and the terminal PGE2 synthase, mPGES1, are increased in kidney cortex of CA-SPAK mice, compared to control or SPAK KO mice. Hydrochlorothiazide (HCTZ) reduced PGE2 to control levels, indicating increased PGE2 synthesis is dependent on increased NCC activity. Immunolocalization studies revealed mPGES1 is selectively increased in the connecting tubule of CA-SPAK mice, implicating low salt-delivery to ASDN as the trigger. Salt titration studies in an in vitro ASDN cell model, mCCD-CL1, confirmed PGE2 synthesis is activated by low salt, and revealed that response is paralleled by induction of mPGES1 gene expression. Finally, inhibition of the PGE2 receptor, EP1, in CA-SPAK mice partially restored potassium homeostasis as it partially rescued ROMK protein abundance, but not ENaC. Similar observations were observed in wild-type mice, undergoing a physiologic remodeling response to dietary potassium restriction. In response to consuming a zero potassium diet (ZKD), which physiologically activates NCC and reduces distal sodium delivery, WT mice increase urinary PGE2 as mPGES1 increases in the late distal tubule and connecting duct. These findings provide new insights into the mechanism by which activation of sodium transport in the DCT causes remodeling of the ASDN.

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