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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  • Genetic and Functional Studies of the Evolutionarily Oldest Natural Killer Receptor, NKp30

    Kinlein, Allison; Ohta, Yuko; 0000-0002-3944-2530 (2021)
    NKp30 is a Natural Cytotoxicity Receptor (NCR) expressed by Natural Killer (NK) cells and other lymphocytes. NKp30 is the only evolutionarily conserved NCR found in all jawed vertebrates and it coevolves with its ligand B7-H6. Using sharks as a model, we found NKp30 gene expression in subsets of mature and immature T cells, suggesting that T cells and NK cells share common features in these primitive vertebrates. To understand NKp30’s evolutionary origin, we examined genomic regions containing NKp30 and its homologs in vertebrates in different Classes. We observed that loci in paralogous regions containing NKp30 homologs are well conserved, suggesting the presence of NKp30 ancestors and other linked immune genes before the emergence of vertebrates 550 million years ago. Indeed, the corresponding region is also present in invertebrates. We hypothesize that this genomic region encompassed the “Primordial Immune Complex,” containing genes playing roles in immunity at the origin of vertebrates.
  • Inhibition of GPR68 Sensitizes GBM to Temozolomide Treatment via the NF-kB Pathway

    Ahmad, Jovanni; Hong, Charles C., 1967-; 0000-0001-9550-8090 (2021)
    Glioblastoma Multiforme (GBM) remains as one of the most aggressive and lethal cancer types, often resulting in poor prognosis. Currently, Temozolomide (TMZ) is the standard chemotherapy for combating GBM. However, GBM’s upregulation of O-6-Methylguanine-DNA Methyltransferase (MGMT) mitigates the alkylating effects of TMZ treatment, generating a dire new need for novel or adjuvant therapy. U138MG is a TMZ-resistant GBM cell line used for the development of new chemotherapy. Here, we investigated whether inhibition of proton sensing GPR68 would decrease MGMT expression and sensitize U138MG cells to TMZ treatment. Using various genetic, protein, and cell-based assays we determined that inhibition of GPR68 may be decreasing MGMT protein expression and sensitizing U138MG to TMZ via the Gq/NFkB pathway. Furthermore, we identified that co-administration of TMZ and OGM resulted in a synergistic decrease in cell growth compared to OGM treatment alone.
  • Bile Acids as Biomarkers and Evolutionary Phenotypes

    Shiffka, Stephanie; Swaan, Peter W.; Kane, Maureen A.; 0000-0002-3571-1836 (2021)
    Bile acids (BAs) are the amphipathic end products of cholesterol metabolism and represent a critical means of cholesterol excretion. BAs have a plethora of functions, including digestive roles, homeostatic feedback loops, energy metabolism, regulation of the microbiome, inflammation, and more. These effects implicate BAs in physiological and pathological processes throughout the body, not just within the enterohepatic circuit. To date, BAs have been linked to the pathogenesis of multiple types of cancer, type 2 diabetes mellitus, metabolic syndrome, and neurological disorders, among others. In health, BA homeostasis is precisely regulated by a process termed enterohepatic circulation (EHC). Several transport proteins are instrumental to this process, and disruptions in any of these transport systems lead to dysregulation of BA homeostasis, further leading to complications such as cholestasis and liver disease. BA metabolism and the EHC are conserved throughout vertebrate evolution, but the BA pool of more modern species has been modified to be more hydrophilic while still retaining properties of digestive surfactants. Though EHC is well-characterized, the understanding of eukaryotic transporters in this process is lacking, especially at the molecular level. Despite the recognition of bile acids as signaling molecules involved in disease progression, there remain numerous BAs that are poorly characterized. This is especially important because BAs are an extremely diverse group of molecules that represent the effects of host and microbiome metabolism. Furthermore, the unique physicochemical properties of these variations confer these molecules with differential levels of cytotoxicity and divergent, sometimes opposing, activation of cell signaling pathways. Thus, the scope of this dissertation is two-fold: first, to further characterize the BA pool in health and injury using cell and animal models; secondly, to use this information in order to probe the transporter responsible for the first step of the enterohepatic circulation, ASBT (SLC10A2). Completion of the first objective yielded improved understanding of BA metabolism in cell culture models and non-human primate laboratory models, as well as in radiation injury in the latter model. Accomplishment of the second objective returned insight into ASBT and BA evolution through the use of multiple vertebrate orthologs.
  • Covariates Associated with Completing Short-Term Residential Treatment for a Substance Use Disorder Among Adults in the U.S.

    Ware, Orrin; Sacco, Paul; 0000-0002-3269-5324 (2021)
    Substance use disorders (SUDs) are associated with harmful outcomes across the biopsychosocial spectrum. Although completion of treatment for SUDs is associated with beneficial outcomes such as improved well-being and reduced mortality, premature treatment termination remains high in the United States. Short-term residential treatment is brief and for more severe SUD. This 3-paper dissertation focuses on exploring covariates of treatment completion in a short-term residential setting for adults with an SUD. Secondary data include the Treatment Episode Data Set Discharges 2017 and the Short-Term Residential Treatment Dataset, which contains data gathered from a Mid-Atlantic treatment facility’s electronic medical records. Paper 1 examines the associations of sociodemographic and substance use characteristics with completion of short-term residential treatment. This paper also has a primary focus on observing sex differences in treatment completion. Results from logistic regression models indicated that men were more likely to complete treatment than were women, nonpolysubstance users were more likely to complete treatment than were polysubstance users, and individuals with alcohol identified as their primary substance were more likely to complete treatment than were individuals with other primary substances. Paper 2 examines the associations between perceived stress, distress tolerance, and treatment completion in the short-term residential SUD treatment setting. Perceived stress and distress tolerance were negatively associated. Men had lower perceived stress and higher distress tolerance than did women. Those who completed treatment had lower perceived stress and higher distress tolerance than did those who were discharged from treatment prematurely. Lower perceived stress was found to predict treatment completion conditional to including a Perceived Stress × Distress Tolerance interaction variable. Distress tolerance did not moderate the relationship between perceived stress and treatment completion. Paper 3 examines a scale based on the theory of planned behavior to predict treatment completion in the short-term residential SUD treatment setting. In a path model, the theory of planned behavior’s constructs attitude and perceived behavioral control positively predicted greater intention to complete treatment. Intention to complete treatment and perceived behavioral control did not have a direct effect on treatment completion.
  • Actin-Like Protein 6A (ACTL6A) Suppresses p21Cip1 Expression to Maintain an Aggressive Cancer Phenotype

    Shrestha, Suruchi; Eckert, Richard (Richard L.); 0000-0002-9550-816X (2021)
    Epidermal squamous cell carcinoma (SCC) and mesothelioma are two distinct but highly aggressive forms of cancer. SCC is a common and highly invasive cancer that arises from the epidermis. The major cause of epidermal SCC is repeated exposure to ultraviolet light and other DNA damaging agents such as oxidative stress which causes mutations eventually leading to increased expression of pro-tumor genes and reduced expression of tumor suppressors. Mesothelioma is highly invasive and lethal cancer that arises from the mesothelial lining and is linked to exposure to asbestos and other toxic agents. Actin-like protein 6A (ACTL6A, BAF53A) is a member of SWI/SNF chromatin remodeling complex that has been implicated in many cancers as a driver of cancer survival and tumor formation. We show that ACTL6A functions to maintain an aggressive cancer phenotype in both SCC and mesothelioma. We further show that ACTL6A reduces expression of the p21Cip1 cyclin-dependent kinase inhibitor and tumor suppressor protein. Biochemical studies reveal that loss of ACTL6A leads to increased p21Cip1 promoter activity, and mRNA and protein expression suggesting transcriptional regulation of p21Cip1 gene. Moreover, chromatin immunoprecipitation studies show that ACTL6A interacts at the p21Cip1 promoter proximal Sp1 site and distal p53-responsive enhancer sites to suppress transcription. We further report that the increase in p21Cip1 upon ACTL6A knockdown is required to suppress the SCC and mesothelioma cancer phenotypes. This suggests that p21Cip1 is the key mediator of ACTL6A function in SCC and mesothelioma. p53 is a key tumor suppressor that interacts with the p21Cip1 promoter to increase expression; however, we show that it may not play a regulatory role in these cancers. These findings suggest that ACTL6A suppresses p21Cip1 transcription to reduce p21Cip1 function as a mechanism to maintain an aggressive cancer phenotype in SCC and mesothelioma.
  • Calcium and BK Potassium Channel Regulation of Circadian Rhythms in the Suprachiasmatic Nucleus

    Plante, Amber; Meredith, Andrea L.; 0000-0002-1010-2348 (2021)
    Mammalian circadian rhythms are driven by a network of neurons in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN exhibits daily (24-hour) rhythms in spontaneous action potential (AP) firing rate that encodes a time-of-day signal that coordinates the timing of circadian physiological and behavioral processes. Large-conductance Ca2+-activated K+ (BK) channels have a major role in driving the diurnal patterns of spontaneous firing in SCN neurons. BK K+ currents are larger at night, correlating with reduced neuronal excitability. The diurnal variation in BK current in the SCN is required for setting the day-night difference in firing frequency. BK currents undergo multi-level regulation by genetic and posttranslational mechanisms as well as functional coupling to Ca2+ channels. Intracellular Ca2+ (Ca2+i) is required for BK channel activation and previous studies have shown BK current is predominantly coupled to two types of Ca2+ sources in the SCN: L-type Ca2+ channels (LTCCs), and ryanodine receptors (RyRs). Circadian rhythms in Ca2+i have also been identified in SCN neurons. However, the Ca2+ channels involved in generating both AP and Ca2+i rhythms have not been clearly identified. First, to determine which Ca2+ channels are involved in AP rhythms, this study measured the impact of Ca2+ channel agonists and antagonists on the circadian parameters of spontaneous AP activity from organotypic SCN slice cultures grown on multi-electrode arrays. Next, to determine which Ca2+ channels are involved in Ca2+i rhythms, this study tested the effects of the same Ca2+ channel pharmacology on the circadian parameters of Ca2+i measured from SCN slice cultures transfected with a fluorescent Ca2+ sensor. Lastly, this investigated a potential mechanism by which LTCCs contribute to firing rate in SCN neurons by examining their ability to activate BK channels under controlled conditions. This study provides insight into the roles of specific Ca2+ sources in neural coding of the circadian time signal in the SCN.
  • Theileria infections in African cattle and buffalo: understanding genetic variation and speciation

    Palmateer, Nicholas; Carneiro da Silva, Joana; 0000-0002-4307-8049 (2021)
    East Coast fever, caused by the apicomplexan parasite Theileria parva, has an estimated annual death toll of over a million cattle in endemic sub-Saharan regions. The African Cape buffalo is the natural reservoir of T. parva and rarely exhibits clinical symptoms when infected, but transmits the parasite to cattle via a tick vector. Previous studies based on a few genetic markers showed that buffalo-derived T. parva subpopulations contain greater antigenic diversity than those from cattle. Interestingly, cattle are infected and killed by T. parva of buffalo origin, but cannot transmit those parasites, suggesting that a degree of host specificity exists. The characterization of genetic variation within and between cattle- and buffalo-derived T. parva is critical to understand the molecular mechanism(s) of host specificity. To overcome obstacles in T. parva biology that prevent the straightforward acquisition of sufficient DNA for whole genome sequencing (WGS), we adapted a DNA capture approach to select T. parva from a mix of parasite and bovine DNA obtained from T. parva-infected bovine lymphocyte cultures. To gain access to variable genomic regions that cannot be characterized through read mapping approaches, we assembled the captured reads de novo. From starting material of <1%-4% parasite DNA in a mixed sample from host and parasite, >98% of sequence reads post-capture are of parasite origin and >97% of the genome is recovered, reflecting the method’s high specificity and sensitivity. We used this whole genome DNA capture followed by sequencing to generate WGS data from 15 cattle- and 24 buffalo-derived T. parva isolates. This resulted in the generation of the first assembly of a buffalo-derived T. parva isolate. Furthermore, we determined that cattle- and buffalo-derived T. parva isolates differ in various measures at levels consistent with speciation. Finally, capture and analysis of members of the T. parva repeat (Tpr) multigene family, which encode some of the most variable antigen families in the species, enabled the study of Tpr evolution and initial inferences of its possible involvement in parasite-host interactions. These results have greatly advanced the study of the T. parva genome and improved our understanding of the evolution of this parasite population.
  • Targeting Zinc Finger Proteins with Exogenous Metals and Molecules: Lessons Learned from Tristetraprolin, a CCCH type Zinc Finger

    Ok, Kiwon; Michel, Sarah L. J.; 0000-0002-7724-8860 (2021)
    Zinc (Zn) plays a key role in inflammatory response, including regulating the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway. Among the signaling proteins involved in the NF-κB pathway, many are known zinc finger proteins (ZFs), including Tristetraprolin (TTP). TTP is a non-classical CCCH-type Zinc Finger protein (ZF), that contains two Cys3His zinc binding domains and is a key regulator of the inflammatory response. TTP is a potential target for exogenous gold (Au) and copper (Cu), as well as hydrogen sulfide, an emerging gasotransmitter. To understand how TTP is targeted by other metals, the interactions of TTP were investigated using a combination of bioinorganic chemistry tools including as optical spectroscopy, native electrospray ionization mass spectrometry (ESI-MS), and X-ray absorption study (XAS). The first metal investigated was Cu(I). I discovered that Cu(I) can bind to the tandem ZF construct of TTP (TTP-2D) and disrupt structure and function. This finding indicates a potential relationship between Cu toxicity and metal-regulation of ZFs. The second metal investigated was Au(III). I discovered that the reactivity of TTP-2D with gold complex leads to Au exchange forming a series of Aux-TTP-2D complexes, with reduction of the gold from Au(III) to Au(I). These protein species are then functionally inactive (no RNA binding). When the same experiments were performed with TTP bound to RNA, the Zn-TTP/RNA complex is not disrupted by the Au-complex suggesting a protective role for RNA. To understand how H2S, a signaling molecule, targets Zn-TTP-2D, its reactivity was determined using a combination of cryo-ESI-MS, fluorescence, and electron paramagnetic resonance (EPR) spectroscopies. We found that the H2S oxidizes the cysteine residues of Zn-TTP via a mechanism that involves atmospheric oxygen, a persulfide intermediate and a radical reaction. The results of these biochemical studies of TTP will be presented in the context of TTP’s biological role. In addition, development of a method to follow Zn speciation in inflammatory cells via liquid chromatography connected to inductively coupled plasma (LC-ICP-MS), will be presented. Here, I use THP-1 cells, which are a human monocyte cell line as a model for inflammation, and demonstrate an approach to separate the zinc-proteome.
  • Use of Machine Learning To Predict COPD Treatments and Exacerbations in Medicare Older Adults: A Comparison of Multiple Approaches

    Le, Tham Thi; Simoni-Wastila, Linda (2021)
    Background: Multiple comorbidities, suboptimal adherence to maintenance medications (MMs), and exacerbations remain clinically important problems among older adults with chronic obstructive pulmonary disease (COPD). To better understand comorbidity profiles and to facilitate risk-based strategies for disease management, this dissertation quantified the prevalence and newly diagnosed rates of comorbidities, and validated predictive models of COPD medication non-adherence and exacerbations in the older Medicare population. Methods: Comorbidities were quantified in COPD beneficiaries and compared with matched non-COPD individuals using multivariable logistic regression. In a cohort of COPD beneficiaries with prevalent and new MM use, logistic and LASSO regressions were used to cross-validate the prediction of one-year non-adherence to MMs using different sets of predictors. A time-varying design was applied to assess improvement in predicting COPD exacerbations of the super learner versus component approaches (logistic regression, elastic net regression, random forest, gradient boosting, and neural network). Results: COPD beneficiaries had significantly increased odds of 40 measured comorbidities relative to matched non-COPD controls. The best-performing models in predicting MM non-adherence were those including initial MM adherence as a predictor, with validated Area Under the ROC Curves (AUC: 0.871-0.881). In predicting COPD exacerbations there were time-varying estimates of predictive accuracy and associations between predictors and the exacerbation outcome. Super learner performed slightly better (AUC: 0.650-0.761) than individual machine learning methods. Conclusions: Comorbidity burden is substantial and increases over time among Medicare older adults with COPD. Generated models achieved good and average discrimination in predicting COPD medication non-adherence and exacerbations, respectively. COPD hospitalization, oxygen supplementation, COPD treatment adherence, and numbers of inpatient visits were the most important predictors of COPD medication non-adherence and exacerbations. Super learner demonstrates a slight improvement compared to component methods, suggesting potential usability in augmenting prediction. Validated models with good discrimination can be adopted using friendly tools to optimizing resources for risk-based management and interventions of COPD.
  • Opposite Roles of Zebrafish Galectins in In Vitro Attachment and Infection by the Infectious Hematopoietic Necrosis Virus (IHNV)

    Abernathy, Kelsey; Vasta, Gerardo R.; 0000-0001-9218-2611 (2021)
    IHNV is a rhabdovirus with a high mortality rate that has major economic impacts on the salmonid fisheries and aquaculture industry. The virus uses cell surface fibronectin as a receptor for attachment and infection, but the exact mechanism remains unknown. Previously published work in our lab and preliminary data revealed that β-galactoside-binding lectins, known as galectins, interact directly with the IHNV envelope glycoprotein to either promote or inhibit viral attachment and infection of fish epithelial cells. The zebrafish tandem-repeat galectin 9 isoform 1 (Drgal9-L1) displays two carbohydrate recognition domains (CRD) joined by a linker peptide that are similar but not identical in binding specificity. The goal of this study was to explore the mechanism of Drgal9-L1-mediated enhancement of IHNV attachment to epithelial cells (EPC cell line). We showed that Drgal9-L1 crosslinks IHNV to cell surface glycans in a carbohydrate-dependent and -specific manner. We determined that crosslinking was dependent on two functional CRDs through the development of a C-terminal mutant protein that did not enhance IHNV attachment or infection of EPC cells. Drgal9-L1 crosslinks IHNV to fibronectin on the cell surface, enhancing viral attachment, in a carbohydrate -dependent and -specific manner. In addition, Drgal9-L1 binds to alternative ligands, β1-integrin and CD147, to increase IHNV attachment. Double antibody inhibition and siRNA knockdown of fibronectin and β1-integrin in EPC significantly reduced Drgal9-L1 mediated attachment of IHNV. We also investigated the protective role of epidermal mucus glycans for preventing Drgal9-L1 mediated viral attachment to the epithelium. All three galectin classes were detected in the zebrafish epidermal mucus, and Drgal9-L1 as well as Drgal1-L2 were found to bind to mucus glycans in a carbohydrate-specific manner. In a plaque assay, mucus coating of the cell monolayer reduced the number of IHNV plaques on the EPC cells in a concentration and volume-dependent manner and annulled the Drgal9-L1 enhancement of viral attachment and infectivity. Finally, we identified an alternative mechanism of Drgal1-L2 antiviral protective activity, as binding of Drgal1-L2 to surface glycosylated receptors or mucus glycans significantly inhibits IHNV attachment. This research has wide-ranging applications for aquaculture disease management, vaccine development, and a general model of galectin-modulated viral attachment.
  • Cancer Mortality among US Solid Organ Transplant Recipients: Novel Methodologies to Estimate Cancer Burden using Linked Population-Based Registries

    Noone, Anne-Michelle; Dorgan, Joanne; Engels, Eric A.; 0000-0001-6997-4004 (2021)
    Background: The solid organ transplant population has an elevated risk of cancer compared with the general population. Excess risk is largely due to immunosuppression. As this population grows, understanding long-term health risks such as cancer is critical. Population-based estimates of cancer mortality are needed since they measure the downstream outcome following a cancer diagnosis. Furthermore, quantifying deaths attributable to cancer can inform priorities to reduce the cancer burden. Methods: Linked transplant and cancer registry data were used to identify incident cancers and deaths among solid organ transplant recipients in the United States (1987-2014). Population-attributable fractions (PAFs) of deaths due to cancer and corresponding cancer-attributable mortality rates were estimated. Cancer-attributable mortality rates computed using the PAF were compared to cancer-specific mortality rates computing using cause of death (COD). The life-years lost (LYL) to cancer were estimated using two methods: an approach using matching to construct a cancer-free cohort and an approach using Cox proportional hazards regression models. Results: Among 221,962 transplant recipients, 15,012 developed cancer. Thirteen percent of deaths (PAF=13.2%) were attributable to cancer, corresponding to a cancer-attributable mortality rate of 516 per 100,000 person-years. Lung cancer was the largest contributor to mortality (PAF=3.1%), followed by non-Hodgkin lymphoma (NHL, PAF=1.9%), colorectal cancer (PAF=0.7%), and kidney cancer (PAF=0.5%). Overall, the cancer-specific mortality rate lower, 368 per 100,000 person-years. Within 10 years post-transplant, the mean LYL was 0.16 years per transplant recipient and 2.7 years per cancer. Cancer accounted for 1.9% of the total LYL expected in this population. Lung cancer was the largest contributor, accounting for 24% of all LYL, and NHL had the next highest contribution (15%). Conclusions: Cancer is a substantial cause of mortality among solid organ transplant recipients resulting in excess deaths and a shortened lifespan. Lung cancer and NHL are major contributors to the cancer burden including LYL to cancer, highlighting opportunities to reduce cancer mortality through prevention and screening.
  • The Creation of Objective Performance Criteria and Generation of Predictive Models among Medical Devices in a Vascular Space

    Gressler, Laura; Shaya, Fadia T.; 0000-0003-2042-2174 (2021)
    Background: Objective Performance Criteria (OPC) have been explored as a tool to address the growing pressures to expedite device approval and enhance active surveillance. Existing data infrastructures can be employed to develop OPC to evaluate the use of devices, and can be further leveraged to develop predictive models. The objective of this dissertation was to: (1) Develop a framework for the creation of OPC, (2) Compare the use of stent, atherectomy, and combination of stent and atherectomy, and (3) Formulate a predictive model used to predict the probability of undergoing a major adverse limb event (MALE) or experiencing death following the aforementioned treatments. Methods: The framework was developed in 3 phases through (1) Review of the literature, (2) Engagement of key stakeholders, and (3) Feedback from an advisory committee. Retrospective cohort studies were conducted using the Vascular Quality Initiative (2010-2018). Logistic regression and the Fine-Gray subdistribution hazard model were used to compare short- and long-term MALE, respectively. A generalized linear model (GLM), a Least Absolute Shrinkage and Selection Operator (LASSO) regularized GLM, a gradient boosted decision tree, and random forest model were compared when used to predict MALE and mortality. Results: The developed framework consisted of 5 elements: (1) Identification of Medical Devices, (2) Engagement of Key Stakeholders, (3) Selection of Data Source, (4) Performance of Appropriate Statistical Analyses, (5) Reporting of Findings. The odds of short-term MALE (0.94;95%CI:0.77-1.14) and hazards of long-term MALE (0.92;95%CI:0.82-1.04) were not significantly different in the combination stent and atherectomy group when compared to stent alone. The most effective predictive model was the gradient boosted decision tree (Area Under the Curve (AUC)= 0.7539) for MALE and the LASSO regularized GLM (AUC=0.7930) for mortality. Conclusions: The developed framework provides a guide and needed foundation for the continued generation of OPC. Applying the identified statistical steps in the framework to an existing data infrastructure showed that patients receiving combination stent and atherectomy do not experience significantly different rates of MALE compared to stent alone. Predictive models generated using the infrastructure demonstrated the ability of machine learning techniques to generate robust predictive models within the vascular space.
  • Incidental Findings in Cone Beam Computed Tomography Images During Prosthodontic Evaluation: Characteristics of Head and Neck Atheromas

    Amarin, Rula Sabah Odeh; Masri, Radi, 1975- (2021)
    Objectives Atheromas can be incidentally detected in routine CBCT images. This study aims to assess prevalence, and risk factors associated with these vascular lesions. Materials and Methods Full-volume CBCT images of 458 patients were evaluated and divided into 4 groups: Subjects with no atheroma, subjects with intracranial atheroma (ICA), subjects with extracranial atheroma (ECA), and subjects exhibiting combined lesions. Age, sex, medical conditions, family history, and size were documented. Results Of the 458 subject scans, 29.9% presented with incidental atheromas. Atheroma’s incidence was significantly higher in older patients and in males compared to females. Patients with atheroma were significantly more likely to have a history of hyperlipidemia, hypertension, and myocardial infarction. Patients exhibiting combined lesions were more likely to have cardiovascular risk factors. Conclusion Incidentally detected atheromas are common and subjects with combined lesions are at higher risk for CVD, and this warrants early referral to medical specialists.
  • The epidemiology of patient to patient transmission of MRSA among critical care patients

    Adediran, Timileyin; Harris, Anthony D.; Thom, Kerri (2021)
    Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial pathogen that leads to an increase in morbidity and mortality. To decrease the spread of MRSA, there is a need to elucidate factors that lead to patient-to-patient transmission in critical care settings. Objectives: Aim 1: To understand if patient-to-patient transmission via HCP mediator differs between high-risk activities by determining the odds of MRSA contamination of the patient from the gown and gloves of the health care personnel (HCP). Aim 2: To determine if isolates found on the gown and gloves of HCP are similar to patient isolates after performing an HCP-patient interaction, using comparative genomic techniques. Methods: Aim 1: This was an observational study of MRSA-positive patients and the HCP who cared for them. We conducted a simulation study of patient-to-patient transmission of MRSA from a HCP vector to a manikin (proxy for the subsequent patient). Using a generalized linear mixed model, we determined the odds of manikin contamination after performing HCP-patient interactions. Aim 2: We selected 95 patient MRSA isolates and their co-isolated HCP gown or glove MRSA isolates using a stratified sampling method. Comparative genomics analyses such as phylogenetic analysis, spa-typing, multi-locus sequence typing (MLST), large-scale blast score ratio (LSBSR), and single nucleotide variant (SNV) analysis were used to achieve this aim’s objective. Results: Aim 1: We observed 103 HCP-patient interactions with 65 MRSA-positive patients and found that subsequent transmission of MRSA from HCP gown and gloves to the manikin proxy occurred 10.7% of the time. There was no association between high-contact patient care activities and MRSA contamination of the manikin following patient care activity (p-value=0.1). Aim 2: Using multiple typing methods, we found that the majority of our isolates were genetically similar. The phylogenetic analysis revealed that 85.2% of paired isolates were similar, and the spa-typing and the LSBSR found that more than 75% of our paired isolates were concordant. However, SNV and MLST identified more than 40% of our paired isolates as discordant. Conclusion: The studies conducted demonstrated patient-to-patient transmission of MRSA via HCP vector, indicating the importance of contact precautions and infection control practices.
  • Determining the Neural Correlates of Burning Mouth Syndrome

    Payano Sosa, Janell; Seminowicz, David A.; 0000-0003-1337-3749 (2020)
    In the United States, nearly 1 million people suffer from burning mouth syndrome (BMS), a chronic orofacial pain condition that is largely unrecognized by the medical community and predominantly affects post- and peri-menopausal women. Relatively little in-depth research is available on the condition, and patients often give up seeking treatment. The pain in BMS arises spontaneously (i.e. in the absence of stimuli), but the mechanisms of this spontaneous pain is unclear, and there is limited research on structural and functional brain changes that may occur in a BMS sufferer. The goal of this dissertation was to investigate the central nervous system mechanisms of pain experienced in BMS. We collected: 8-day diaries, morning and afternoon quantitative sensory testing of both orofacial and forearm regions; afternoon structural and functional MRIs, and questionnaires from 27 BMS patients and 33 healthy post-menopausal women. Our hypotheses that, compared to healthy participants BMS patients have: higher pain sensitivity, especially in orofacial regions during the afternoon; lower grey matter volume and higher functional connectivity in nociceptive pathways associated with noxious heat during rest and evoked thermal pain, even after accounting for anxiety, were not supported. Instead, we found a time-of-day-dependent effect during warm detection and cold detection of face and forearm; lower grey matter volume of the dorsolateral prefrontal cortex (DLPFC), and higher grey matter volume of the inferior temporal gyrus and parabrachial nucleus (PBN); lower PBN connectivity with the DLPFC and primary somatosensory cortex (S1); higher connectivity of the right lateral hypothalamus (LH) with posterior insula during warm condition; connectivity of right medial hypothalamus and LH to left DLPFC and right PBN to bilateral S1 not associated with anxiety in BMS compared to healthy participants. Altogether, BMS showed abnormal responses to innocuous stimuli. This was supported by fMRI data, where connectivity differences were mostly present during innocuous stimulation. These altered sensory and brain responses could reflect heightened anticipation of thermal stimuli (both pain-specific and non-pain specific) associated with disruption of communication between regions associated with negative affect of pain (insula), attention modulation of pain (left DLPFC), somatosensation (S1), and thermoregulation (LH and PBN).
  • Prescription Opioids and Traumatic Brain Injury in Older Adults

    Herrera, Anthony; Albrecht, Jennifer S.; 0000-0001-5345-1241 (2021)
    Older adults using opioids in the US increased annually from 1999 to 2011. This is a significant public health concern because prescription opioid use increases fall-risk, the most common cause of traumatic brain injury (TBI) among older adults and a leading cause of disability and mortality. No studies have investigated the association between prescription opioid use and TBI. This dissertation characterized prescription opioid use in Medicare beneficiaries aged ≥65 years and examined the relationship between opioid use and incident TBI. Using Medicare administrative claims data from 2010 – 2015, I assessed how older adult prescription opioid use has changed over time, as well as changes in opioid prescriber specialties and pre-opioid diagnoses/ procedures. I also used these data to estimate risk for TBI associated with prescription opioid use. Next, I used R Adams Cowley Shock Trauma Center Registry (STR) data from 2015 – 2019 to explore the relationship between prescription opioid use and TBI injury mechanisms and severity. I found that the percent of older adults using prescription opioids decreased from 35.4% to 32.9% (p<0.001). Primary care physicians prescribed the most opioids, but their share of prescriptions dropped from 59.0% to 52.8% (p<0.001). Back pain remained the most common diagnosis among older adult opioid users, unchanged over time (24.1% to 25.3%, p=0.594). Opioid use increased TBI risk (odd ratio: 1.34, 95% confidence interval: 1.28 - 1.40) among older adults, regardless of opioid dosage and duration differences. Compared to non-users in the STR data, older adult opioid users who sustained TBI were 85% more likely to be injured in a fall compared to a motor vehicle incident (OR 1.85, 95% CI 1.20 – 2.86). Opioid use was associated with a 39% increase in sustaining more severe TBIs. (OR 1.39, 95% CI 1.09 – 1.79). This dissertation found opioid prescriptions decreasing among older adults. This parallels reductions in primary care opioid prescribing as well as changes in opioid-related diagnoses and procedures. These are the first studies to provide evidence that prescription opioids raise TBI risk and severity in older adults. Future studies could refine the association between opioid and TBI using data with definite dosing details
  • Excipient Screening and Spray Drying Process Optimization of Cell-based and Protein-based Biologics with Feasibility Demonstration of Oral Delivery

    Lu, Yuwei; Hoag, Stephen W.; 0000-0001-7081-3611 (2021)
    Biologics-based therapeutics, such as proteins and cells, have gained increasing popularity over the past few years. Formulation and process strategies have been applied to achieve quality biologics products, prioritizing desired efficacy and safety over shelf –life. In this thesis research, spray drying formulation development strategies were developed for a novel biotherapeutics ABAB antibody producing Sb-ABAB cells for the treatment of Clostridium difficile infection (CDI) and a recombinant human serum albumin (rHSA) using carbohydrate, protein-based, or other excipients and excipient combinations. Excipient functionality was explored using spectroscopy-based chemometrics investigation. In addition, novel mass spectroscopy based in cell-fast photochemical oxidation of proteins (ICFPOP-MS) was used in combination with homology labeling to probe the excipient - protein interactions. In addition, excipients and water activity effects on the storage stability of the Sb-ABAB spray dried product were explored to optimize shelf life. Subsequently, multivariate data analysis and design of experiments (DOE) were applied to explore the effects of spray dry process parameters on critical quality attributes of the protein- based and cell-based biological products. The spray dried protein/cell powders were further developed into oral dosage forms acceptable for patient use, such as tablets and capsules. The feasibility of developing oral protein tablets using IgG as model protein and enteric-coated Sb-ABAB capsules were explored. For example, compression force, particle size and storage relative humidity effects on the stability of the IgG tablets were investigated via analytical and biophysical analysis. In addition, colon targeted delivery of the Sb-ABAB minicapsules was developed and in vitro release assay was conducted to evaluate the enteric coating efficiency. In conclusion, cell-based and protein-based therapeutics were successfully spray dried while achieving desirable stability during the drying process. Furthermore, protein tablets and controlled release Sb-ABAB capsules were successfully developed, offering a novel alternative delivery approach to biologics products.
  • Surface Roughness of Zirconia Produced by Additive and Subtractive Manufacturing

    Triana, Frank James; Masri, Radi, 1975- (2021)
    Purpose – The purpose of this in vitro study was to compare surface roughness of full contour zirconia restorations produced by additive and subtractive manufacturing Materials and Methods – Full contour restorations were designed using 3Shape Dental System. The stl files were exported and utilized to guide production of all specimens. Zirconia samples were manufactured by two methods – additive manufacturing (n=10) and subtractive manufacturing (n=18). A two-step polishing protocol was used following sintering. All specimens were subject to profilometry to measure average Ra values. Ra values for both groups were compared. Statistical analysis was performed using t-test (p=0.05). Results – The average Ra value for zirconia restorations in the subtractive manufacturing group was 0.35 ±0.07µm while average Ra for additive manufacturing groups was 1.06 ±0.49 µm. Differences were statistically significant (p < 0.00001). Conclusions – Zirconia restorations produced by subtractive manufacturing were significantly smoother than those produced by additive manufacturing even after post-sintering polishing.
  • Optimizing Pain Management in Medically Complex Long-Term Care Residents

    Kuzucan, Aida; Simoni-Wastila, Linda; 0000-0003-0893-7028 (2021)
    Problem statement: While much needed clinical research has emphasized appropriate opioid stewardship in the general population, the needs of long-term nursing home care (LTC) residents remain largely ignored. Methods: This dissertation identified emerging trends in opioid therapy and initial opioid dosing patterns among LTC Medicare beneficiaries using Medicare Parts A, B and D claims, the Minimum Data Set 3.0 (MDS) and LTCFocus datasets. Aim 1 is a repeat cross-section study using resident and facility adjusted generalized estimating equations (GEE) to examine patterns of opioid use alone and in conjunction with pain-adjuvant medications among general, hospice, cancer, non-cancer chronic pain and dementia-related LTC stays from 2011 to 2015. Aim 2 identifies common patterns of average morphine equivalent daily dosing (MEDD) across six 30-day intervals starting with the first opioid prescription using latent class growth modeling (LCGM). Multivariate multinomial regression quantifies associations between different opioid use patterns over time and resident characteristics. Aim 3 accesses the odds of falls among residents with the highest probability of belonging to each of the commonly identified opioid dosing patterns with a facility clustered GEE model. Results: From 2011 to 2015, adjusted analyses found no constant significant changes in dose, duration, or frequency of opioid use. Increased use of anticonvulsant and skeletal muscle relaxants in opioid-related stays, particularly among residents with dementia, were found. LCGM identified four common opioid dosing patterns; extended high, short-term, intermittent and restart. Almost half of LTC residents received extended high opioid dosing. Multinomial regression found significant associations between sex, race, U.S. geographical region, pain diagnosis and receipt of other pain treatments with receipt of extended high dose therapy. Fall odds were found to be similar in the extended high and short-term groups. Models did find increased odds of falls in groups with less opportunity to develop tolerance (i.e., the restart and intermittent groups). Findings were not consistently significant in stratified analyses. Conclusions: Opioid use varies by resident characteristics. Opioid dosing varies over the course of therapy. More research on what factors lead to decisions regarding pain treatment and the impact of opioid dosing strategies on health-related outcomes are warranted.
  • Metagenome and Metatranscriptome Analysis of the Subgingival Bacteria in Periodontal Disease. A Systematic Narrative Review

    Wohl, Hirschel; Aichelmann-Reidy, Mary Beth (2021)
    The main purpose of this systematic narrative review is to determine the difference in abundance of bacteria and bacterial genes of subgingival microflora of human periodontal pockets compared to healthy sites, via Metagenomic and Metatranscriptomic analyses. Databases EMBASE and MEDLINE were searched for articles, with earliest records from 1978. Main outcome measures included: 1) Bacterial genera and/or species significantly increased 2) Most prevalent or significantly upregulation of genes. Ten studies met selection criteria and were included in the study. Nine studies were cross-sectional, and one was longitudinal. Main results showed trends of specific bacteria and genes found in periodontal pockets. However, within the limitations of this narrative review, trends of abundant bacteria and genes does not imply these specific species or genes are actively participating in disease progression. Nine of ten included studies were cross-sectional in design with eight studies being metagenome based and not able to measure gene expression.

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