Medicine and Health Sciences Commons^™

The Multilevel Factors Facilitating Or Impeding Healthcare Access Among Refugees Residing In Bexar County Texas, Howaida Werfelli

Dissertations and Theses (Open Access)

The goal of this study was to increase understanding of healthcare access among refugees by investigating the multilevel factors that facilitate or impede healthcare access among refugees who have resettled in Bexar County, Texas. The multilevel factors facilitating or impeding access to healthcare for refugees resettled in Bexar County were identified as follows: health literacy, level of educational attainment, proficiency (reading, writing and, speaking) in English, proficiency (reading, writing and speaking) in native language, translation services, public transportation, income level, a shortage of healthcare providers, navigation of the healthcare system, the fragmentation of the healthcare system, insurance status, staff shortages …

Health Disparities Across Funcitonal Disability Groups, Katherine Sanches

Dissertations and Theses (Open Access)

Background: People with disabilities experience higher rates of chronic disease and poor health status compared to those without disability. People with disabilities do not participate in community health programs to the same degree as those without disability due to social, programmatic, and environmental barriers. The Community Health Inclusion Index (CHII) is a community health assessment tool which evaluates the degree to which community-level health promoting opportunities to promote nutrition and physical activity are inclusive and accessible to people with disabilities. The CHII assess barriers to inclusion across five domains: build environment, equipment, program/services, staff, and policies. Objective: The purpose of …

Bst2 Isoforms: Distribution And Potential Use In Cancer Therapeutics, Ahmed Muhsin

Dissertations and Theses (Open Access)

Identifying a cancer-specific cellular target is one of the key factors that can pave a “bench to the bedside” path of a target therapy. Bone marrow stromal cell antigen 2 (BST2) is a raft-associated type II transmembrane protein with an unusual topology. Analyses showed a variable degree of BST2 expression in most organs. Two research groups identified different BST2 isoforms of BST2 generated by posttranscriptional modification. In this research, I studied the long BST2 isoform’s distribution in breast tissue and B cell lines using the novel monoclonal antibody (MAb) LA5, an anti-BST2-long MAb. This approach revealed the expression of the …

Aging Lowers Pex5 Levels In Cortical Neurons In Male And Female Mouse Brains, Ndidi-Ese Uzor

Dissertations and Theses (Open Access)

Peroxisomes are small organelles with critical functions: lipid synthesis, breakdown of reactive oxygen species by antioxidant enzymes, and amino acid degradation. In the brain, peroxisomal lipids make up the myelin sheath. Brain peroxisomal dysfunction leads to lipid disruption or neurological consequences if key peroxisomal proteins are absent. Still, it is unclear how peroxisomes are affected in neurodegenerative diseases and in normal brain aging. This work examines peroxisomal markers in three settings: 1) in a neuronal and 2) animal model of Huntington disease (HD), where mutant huntingtin (mHtt), the causative protein in Huntington disease pathogenesis is expressed, and 3) in the …

Cellular And Circuit Properties Of Slow Oscillations In The Thalamic Reticular Nucleus, John O'Malley

Dissertations and Theses (Open Access)

During sleep, neurons in the thalamic reticular nucleus (TRN) generate distinct types of oscillatory activity. While the reciprocal synaptic circuits between TRN and sensory thalamic nuclei underlie the generation of sleep spindles, the mechanisms regulating slow (<1 >Hz) forms of thalamic oscillations are poorly understood. Under in vitro conditions, in the absence of synaptic inputs, TRN neurons can generate slow oscillations in a cell-intrinsic manner. Activation of postsynaptic Group 1 metabotropic glutamate receptors (mGluR) leads to long-lasting plateau potentials thought to be mediated by both T-type calcium currents and calcium-activated nonselective cation currents (I_CAN). However, the identity of …

A Screen For Peptides Targeting Chemoresistant Metastatic Triple-Negative Breast Cancer, Shraddha Subramanian

Dissertations and Theses (Open Access)

Cancer metastasis is the principal cause of most cancer-associated morbidities. While radiotherapy, hormone therapy, and novel therapeutic strategies, including immunotherapy, have shown promise in inhibiting tumor growth, chemotherapy remains the mainstay in the clinical management of metastatic progression. This is often the case in triple-negative breast cancer (TNBC), an aggressive breast cancer subtype where tumorigenesis is independent of HER-2, progesterone, or estrogen receptor expression. Despite improving TNBC prognosis, recent studies report that after chemotherapy administration, TNBC drug-tolerant tumor cell survival, relapse, and metastatic dissemination may be promoted. Overcoming drug resistance exhibited by metastatic tumor cells is a challenge owing to …

Longitudinal Clonal Lineage Dynamics And Functional Characterization Of Pancreatic Cancer Chemo-Resistance And Metastasization, Chieh-Yuan Li

Dissertations and Theses (Open Access)

In recent years, technological advancements, such as next-generation sequencing and single-cell interrogation techniques, have enriched our understanding in tumor heterogeneity. By dissecting tumors and characterizing clonal lineages, we are better understanding the intricacies of tumor evolution. Tumors are represented by the presence of and dynamic interactions amongst clonal lineages. Each lineage and each cell contributes to tumor dynamics through intrinsic and extrinsic mechanisms, and the variable responses of clones to perturbations in the environment, especially therapeutics, underlie disease progression and relapse. Thus, there exists a pressing need to understand the molecular mechanisms that determine the functional heterogeneity of tumor sub-clones …

Development Of A Ct Metal Artifact Management Algorithm For Proton Therapy Planning (Ampp) For Head And Neck Cancer Patients, Daniela Branco

Dissertations and Theses (Open Access)

Purpose: Dental amalgams (high Z materials) are common sources of artifacts in Head and Neck (HN) images. Commercial artifact reduction techniques have been offered, but many are impractical, produce inaccurate CT images or are not clinically available, thus not widely implemented. The goal of this work is to use CT gantry tilts to develop and evaluate a stereoscopic HN metal artifact management algorithm and investigate its improvement in proton treatment planning.

Methods: The in-house CT metal artifact management method for proton planning (AMPP) uses two angled CT scans to generate a single image set with no metal artifacts posterior …

Characterization Of Treatment Planning System Photon Beam Modeling Errors In Iroc Houston Phantom Irradiations, Mallory Glenn

Dissertations and Theses (Open Access)

In radiation therapy, proper commissioning of the treatment planning system’s (TPS) dose calculation algorithm is critical because any errors in this process impact all treatment plans prepared in the system. Previously, TPS errors have been identified as a major cause for poor phantom irradiation performance, which may also mean that patients are treated suboptimally. The purpose of this work was to investigate the TPS beam modeling developed by the radiotherapy community to understand where inconsistencies may arise, which variables are most susceptible to variations, and in what way changing these variables can alter dose calculations.

Using the Imaging and Radiation …

Bringing Til Therapy Beyond Melanoma: Advancing The Treatment Of Advanced Pancreatic And Ovarian Cancers, Donald Sakellariou-Thompson

Dissertations and Theses (Open Access)

The success of checkpoint blockade immunotherapy (CBI) has reinvigorated the cancer therapy field, particularly for advanced melanoma which has doubled the survival rates compared to 20 years ago. However, there are many solid tumor types that are yet to receive substantial benefit from this groundbreaking therapy, two of which are pancreatic cancer (PDAC) and ovarian cancer (OvCa). As such, the 5-year survival rate for PDAC and OvCa stand at 9% and 28% respectively. Despite the lack of efficacy of CBI so far, there is still evidence for the role of immune control in these cancers as evidenced by presence of …

Directed Evolution Of Macrocyclic Peptides For Inhibition Of Autophagy, Joshua Gray

Dissertations and Theses (Open Access)

In recent decades it has become increasingly clear that induction of autophagy plays an important role in the development of treatment resistance and dormancy in many cancer types. Chloroquine (CQ) and hydroxychloroquine (HCQ), two autophagy inhibitors in clinical trials, suffer from poor pharmacokinetics and high toxicity at therapeutic dosages. This has prompted intense interest in the development of targeted autophagy inhibitors to re-sensitize disease to treatment with minimal impact on normal tissue. We utilized Scanning Unnatural Protease Resistant (SUPR) mRNA display to develop macrocyclic peptides targeting the autophagy protein LC3. The resulting peptides bound LC3A and LC3B—two essential components of …

Investigating The Role Of Quaking In Antigen Uptake And Cross-Presentation By Dendritic Cells, Yating Li

Dissertations and Theses (Open Access)

Dendritic cells (DCs) are considered the most potent antigen presenting cells (APC) due to their superior capability of cross-presenting exogenous antigens to CD8⁺ T cell for strong adaptive immune responses. They internalize foreign antigens by phagocytosis, endocytosis or macropinocytosis, which are then processed in endosomal compartments and loaded onto MHC Class I molecules. However, the molecular mechanisms regulating exogenous antigen uptake and cross-presentation by DCs are not fully understood.

In this study, we discovered that an RNA-binding protein, Quaking (QKI) plays a pivotal role in antigen uptake by DCs. Our previous studies in neural stem cells and microglia have …

Active Magnetic Radiation Shielding For Long-Duration Human Spaceflight, Kristine Ferrone

Dissertations and Theses (Open Access)

Exploration of interplanetary space presents dramatic hazards to human survival.

Space radiation hazards outside the protection of the Earth’s magnetosphere can

produce both acute and chronic health risks and thus become limiting factors for

NASA’s planned mission to Mars by the 2030s. Radiation exposure on a Mars mission

is delivered primarily by high energy ions from galactic cosmic rays and moderate

energy protons from solar particle events. The chronic radiation dose due to galactic

cosmic rays on a typical Mars mission is on the order of 1 Sv, and additional acute

radiation dose from solar flares can reach over 4 …

Targeting Unique Domains Of Lsd1 Regulates Pediatric Glioma Innate Immunity And Nk Cell Metabolism, Cavan Bailey

Dissertations and Theses (Open Access)

Regulation of chromatin accessibility is a key mechanism of cellular identity, allowing different tissues to develop using the same DNA template. Cancers will often hijack these epigenetic pathways, reactivating developmental genes to drive growth and deactivating tumor suppressor and immune recognition genes. Chromatin-modifying proteins deposit and remove chemical moieties from histone tails to aid in governing gene expression, and these proteins have become a new therapeutic target in cancer. Traditional chemotherapeutics aim to damage DNA, dysregulate cell division, or block hormonal growth signals, but epigenetic therapy can target vulnerabilities specific to cancer cells and broadly change gene expression patterns that …

Investigating The Metabolic Progression Of Glioblastoma With Hyperpolarized Magnetic Resonance, Travis Salzillo

Dissertations and Theses (Open Access)

Rapid diagnosis and therapeutic monitoring of aggressive diseases such as glioblastoma (GBM) can improve patient survival by providing physicians the time to optimally deliver treatment. This includes early in development, while the tumor is still manageable, or following initial therapy, when alternative treatments should be considered. The main goal of this project was to determine whether metabolic imaging with hyperpolarized magnetic resonance spectroscopy (MRS) could detect changes in tumor progression more rapidly than conventional anatomic magnetic resonance imaging (MRI) in patient-derived GBM murine models. To comprehensively capture the dynamic nature of cancer metabolism, in vivo pyruvate-to-lactate conversion with hyperpolarized MRI, …

Mechanistic Insights Into Vancomycin Resistance In Clostridioides Difficile, Ayesha Mahmood

Dissertations and Theses (Open Access)

C. difficile is a nosocomial, opportunistic pathogen that has become more hypervirulent over the last decade. Vancomycin is currently a frontline antibiotic for the treatment of C. difficile infections. Yet, strains of C. difficile are becoming non-susceptible to vancomycin. Emergence of the vancomycin non-susceptible phenotype has led to various questions including: What resistance elements are present that might contribute to the phenotype? Are these elements located on the chromosome or a plasmid? Where did these elements originate from? To address these questions, whole genome sequence analysis was performed to survey genes that may be involved in the vancomycin non-susceptible phenotype. …

Methods To Investigate Hyperthermia Induced By Tumor Treating Fields, Ruchi Singh

Dissertations and Theses (Open Access)

Tumor Treating Fields (TTFields) are an antineoplastic treatment delivered via application of alternating electric fields using insulated transducer arrays placed directly on the skin in the region surrounding the tumor. TTF’s is a non-invasive application of low-intensity (1-3 V/cm), intermediate-frequency (100-500 kHz) alternating electric fields. The predominant mechanism by which TTFields are thought to kill tumor cells is the disruption of mitosis through the depolymerization of microtubules and interruption of the spindle structure leading to mitotic catastrophe and the formation of non-viable daughter cells. Tumor Treating fields do not stimulate nerves and muscle because of their high frequency, and do …

Histological And Functional Characterization Of Cervical Spinal Cord Injury After Graded Contusion, Chrystine Gallegos

Dissertations and Theses (Open Access)

Most spinal cord injuries (SCIs) are cervical contusions and result in deficits for both locomotion and reaching and grasping functions. Previous studies have characterized histological and functional deficits in locomotion using primarily thoracic contusions, but most patients have cervical injuries. Damage to descending long spinal tracts (dLSTs) is one well-established cause of functional loss after SCI and has been explored in laceration and transection models, but these are not clinically relevant. In this study, I will explore the histological and functional deficits after graded cervical hemicontusion SCI and examine the potential contribution of different histological deficits to forelimb function after …

Statistical Methods For Resolving Intratumor Heterogeneity With Single-Cell Dna Sequencing, Alexander Davis

Dissertations and Theses (Open Access)

Tumor cells have heterogeneous genotypes, which drives progression and treatment resistance. Such genetic intratumor heterogeneity plays a role in the process of clonal evolution that underlies tumor progression and treatment resistance. Single-cell DNA sequencing is a promising experimental method for studying intratumor heterogeneity, but brings unique statistical challenges in interpreting the resulting data. Researchers lack methods to determine whether sufficiently many cells have been sampled from a tumor. In addition, there are no proven computational methods for determining the ploidy of a cell, a necessary step in the determination of copy number. In this work, software for calculating probabilities from …

Using Spatial Methods To Better Understand Food Insecurity And Snap Under-Participation In Texas, Ryan Ramphul

Dissertations and Theses (Open Access)

The overall objective of this research is to use spatial methods to better understand food insecurity and SNAP under-participation in Texas. Paper 1 assesses whether a sample of community dwelling Medicare and Medicaid beneficiaries, who screen positive for food insecurity at healthcare locations in Harris County, exhibit a spatial pattern in terms of where they live. In other words, it tests whether or not there are statistically significant neighborhood hot spots or cold spots of food insecurity against a null hypothesis of complete spatial randomness. This approach is novel because it uses address-level data on patients who report being food …

Physician Burnout: Slowing The Burn Through Positive Deviance Strategies, Swapna Reddy

Dissertations and Theses (Open Access)

Introduction: Affecting 42% of physicians in the United States, “physician burnout” is considered a public health crisis with adverse impacts for personal providers, patients and organizations. Though much research has been devoted to the existence and causes of burnout, to date few studies have been conducted to identify factors associated with physician fulfillment. Aims: This dissertation research was intended to increase and improve knowledge of factors effective in contributing to physician professional fulfillment utilizing a Positive Deviance based approach. To that end, two studies were conducted: the first, a narrative review of the literature to identify specific correlates of physician …

Bayesian Modeling Of Censored Data With Application To Meta-Analysis Of Immunotherapy Trials, Xinyue Qi

Dissertations and Theses (Open Access)

My dissertation builds on a systematic review of 125 clinical trials reporting on treatment-related adverse events (AEs) associated with PD-1/PD-L1 inhibitors published from 2010 to 2018. The motivating dataset contained the following study-level components extracted from each publication: trial name, number of treated patients, selected immunotherapy drug, dosing schedule, cancer type, number of AEs within each category, and the pre-specified criteria for AE reporting. The number of AEs were reported based upon all-grade (Grade 1-5) and Grade 3 or higher (Grade 3-5) severity. My overall objective was to increase our understanding of the toxicity profiles of five most common cancer …

Functional Heterogeneity And Metabolic Adaptation Of Fibroblasts In Cancer, Lisa Becker

Dissertations and Theses (Open Access)

The tumor microenvironment is comprised of a multitude of cell types producing a milieu of cytokines, growth factors an extracellular matrix. Together, this intricate network of cells plays highly critical roles in determining a tumor’s potential to progress and metastasize. As the predominant cell types in the tumor microenvironment, cancer-associated fibroblasts (CAFs) are a key component in the regulation of tumor development and progression, but their exact functions in tumorigenesis remain poorly understood. This is partly due to the considerable heterogeneity amongst these cells, which confounds the characterization of their roles within the tumor microenvironment. Nevertheless, recent studies have provided …

Safe Patient Handling – A Case For National Legislation, David O. Oba

Dissertations and Theses (Open Access)

Introduction: This study examined the effectiveness of Safe Patient Handling (SPH) legislations in difference states across the country. In January 2006, the state of Texas legislated the Safe Patient Handling and Movement Practices Act which required all hospitals and nursing homes to implement safe patient handling and movement program. To date, 10 other states have enacted law or regulations to control work-related musculoskeletal disorders (MSDs) among healthcare workers (HW). Despite the effectiveness of these policies in the individual states, MSDs remain prevalent among HW nationwide. Hence, the call for national legislation. Methods: Using the state-level incidence rate data from the …

Physician Hospital Arrangement Influence On Nonprofit Hospital Quality,Financial Performance And Community Benefit Expenditures, Andrea Cervin

Dissertations and Theses (Open Access)

Federal policy has encouraged hospitals to provide certain quality outcomes and cost containment. Hospitals have responded by forming physician hospital organizations in attempts to achieve quality outcomes and capture reimbursements. At the same time, federal policy has awarded hospitals with nonprofit status with the requirement to provide community benefits in exchange for the tax exemption they receive. With the formation of physician hospital organizations, there remains the question of whether hospitals are achieving desired quality metrics and whether hospitals are financially viable. There is also public and media interest recently regarding whether nonprofit hospitals fulfill their obligations for community benefit …

T​He​ E​Ffect​ ​Of​ U​Nconventional​ G​As​ ​And​ O​Il​ D​Rilling​ E​Missions​ ​On​ A​Sthma​ ​And​ R​Espiratory D​Iseases​ ​In​ ​The​ B​Arnett​ S​Hale​ ​Of​ T​Exas, Stella A. Okoroafor

Dissertations and Theses (Open Access)

Unconventional gas and oil drilling (UGOD) has increased substantially in the United States for more than a decade. The resultant environmental unsafe air pollution effects of UGOD both locally and regionally have been well documented in the literature. Despite the dramatic increase in unconventional well drilling and the toxicant exposure, the health consequences of UGOD remain largely uncertain. This study assesses the relationship between active wells and healthcare use for respiratory diseases by zip code from 2004 to 2008 in the Barnett shale area of Texas. The first modern shale gas well was drilled in the Barnett shale area of …

A Geospatial Examination Of The Association Between Geographic Food Access And Food Insecurity In Central Texas: The Role Of Race/Ethnicity And Urbanicity, Kathryn Janda

Dissertations and Theses (Open Access)

Food insecurity is a public health issue that affects one in ten Americans, one in seven Central Texans, and is associated with malnutrition, chronic disease, and obesity. Geographic food access is the most intervened upon aspect of food insecurity and is often measured objectively through mapping software, such as ArcGIS. Yet when geographic food access is only measured in terms of distance to food retail, analyses do not full capture the nuances of community context. Thus, other sources of data, like survey data, and demographic indicators, such as race/ethnicity and urbanicity, should be incorporated into the research exploring the association …

Determining The Drivers Of Quality Of Life In Hiv Patints Treated With Antiretroviral Therapy In Subsaharan Africa, Oubote Sangbana

Dissertations and Theses (Open Access)

During the last decade, HIV in sub-Saharan Africa has shifted from a fatal disease to a chronic condition thanks to the expansion of antiretroviral therapy (ART). As a result, the focus of care has transitioned from survival to quality of life (QoL), and the latter has become a significant outcome measure during patient follow up. Yet, the determinants of QoL among HIV patients in western and central Africa are not well known. The objective of this dissertation was to determine the main factors associated with QoL among ART-treated HIV adult patients in western and central Africa to ensure healthcare providers …

Utility Of Plasma Biomarkers In The Validation Of Reported Loc & Pta For Gcs 13-15 Patients: A Track-Tbi Pilot Study, Jeffrey Brennan

Dissertations and Theses (Open Access)

Depending on a brain injury patient to accurately report their duration of unconsciousness and amnesia is clearly flawed. We constructed biomarker-based models to validate these self-reported measurements using a GCS 13-15 subset of participants from TRACK-TBI, a multi-institutional study on traumatic brain injury. Potential covariates were assessed for significant interactions with biomarker level. We report that the predictions of LOC and PTA failed. GFAP exhibited the most consistent serum level increase between categories of both LOC and PTA. Given a number of issues with the study sample, we recommend continued investigation on the prediction of LOC and PTA using a …

The Course Of Acute Stress Disorder And Post Traumatic Stress Disorder In Parents With Infants In The Neonatal Intensive Care Unit, Caroline Bertsch

Dissertations and Theses (Open Access)

NICU parents have up to a 60% chance to develop acute stress disorder (ASD) and/or post-traumatic stress disorder (PTSD) during or after their baby’s NICU stay. Emotional and demographic factors contributing to ASD/PTSD have been previously identified. Although support factors desired by NICU parents have been described, it has not yet been determined how the presence or absence of these desired support factors may impact the development of ASD/PTSD. English and Spanish speaking parents over the age of 18 were eligible to participate in a survey that assessed stress, coping and support in the NICU. Participants also completed a validated …