Medicine and Health Sciences Commons^™

Measurement Of The Electron Return Effect Using Presage Dosimeter, Gye Won Choi

Dissertations & Theses (Open Access)

MR-guided radiation therapy (MRgRT) provides benefits such as superior soft tissue contrast, no imaging dose, and functional imaging capacities, but it also has concerns to be addressed. The electron return effect (ERE) refers to dose enhancement at the interface between different media, caused when radiation is delivered in the magnetic field. The ERE poses clinical concerns in MRgRT because it significantly enhances the dose at interfaces, and the intensity and pattern of the dose enhancement depends on many factors. The ERE results in a complex pattern of dose enhancement over a three-dimensional (3D) volume around tissue interfaces inside the patient …

Bias And Variability In Image-Based Volumetric Yttrium-90 Dosimetry, Wendy Siman

Dissertations & Theses (Open Access)

90Y-microsphere therapy has been widely accepted as a treatment option for both primary and metastatic liver tumors where the patients are ineligible for surgical resection and external beam radiation therapy. The prognosis of untreated patient having liver cancer is very poor with life expectancy less than a year at advance stage. Hence the ability to predict treatment efficacy right after the treatment from post-therapy imaging will help personalize treatment strategies and achieve better outcome. Such prediction can be modeled from correlation of dose and tumor response metrics.

It has been shown that local dose deposition method can generate dose map …

Determining Mechanisms Of Response To Polo-Like Kinase 1 Inhibition In Non-Small Cell Lung Cancer, Ruchitha Goonatilake

Dissertations & Theses (Open Access)

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide. The discovery of genetic alterations in some patients (~15%) has made it possible to use targeted therapies without the use of chemotherapy. To identify potential therapeutic targets in NSCLC, we systematically evaluated two cancer cell line databases with sensitivity data for a broad range of drugs. We identified polo-like kinase 1 (Plk1) as the most promising target for further investigation based on a subset of sensitive cell lines and inhibitors that were in advanced clinical development. To identify potential biomarkers of response and mechanisms of Plk1 inhibitor-induced …

Understanding The Mechanism And Extent Of Vlse Recombination In Borrelia Burgdorferi Using Next-Generation Sequencing, Surabhi Tyagi

Dissertations & Theses (Open Access)

B. burgdorferi, the causative agent of Lyme disease, have an elaborate antigenic variation system that involves varying the sequence of vlsE. Previous studies have shown that vlsE antigenic variation occurs continuously inside mammalian hosts. Variation has not been shown previously to occur in in vitro or in ticks. We hypothesized that the induction of vlsE recombination requires contact with dense arrays of host tissue cells and/or ECM components. To test this hypothesis, two methods, quantitative PCR and high-throughput sequencing were used determine the extent and nature of vlsE recombination within mouse tissues and in vitro model systems. Using these …

A Phase I Dose-Escalation Study Of The Braf Inhibitor Vemurafenib In Combination With The Mtor Inhibitor Everolimus In Subjects With Advanced Cancer, Javier Munoz

Dissertations & Theses (Open Access)

Vemurafenib has been approved in the United States for the treatment of relapsed or refractory BRAF mutation positive malignant melanoma and is being investigated in various other malignancies. The RAS/RAF/MEK/ERK (MAPK) pathway is critical to cell proliferation in many human cancers. The mTOR inhibitors are well known to exert profound anticancer effects across malignancies through inhibition of the PTEN/PI3K/AKT/mTOR (mTOR) pathway. We hypothesize that the toxicity profile of the combination of vemurafenib and everolimus will be well tolerated. The primary objective is to find the maximum tolerated dose (MTD) and the toxicity of the combination of vemurafenib and everolimus following …

An Automated Syringe Pump System For Improving The Reproducibility Of Dynamic Hyperpolarized Mri Phantoms, Harlee G. Harrison

Dissertations & Theses (Open Access)

AN AUTOMATED SYRINGE PUMP SYSTEM FOR IMPROVING THE REPRODUCIBILITY OF DYNAMIC HYPERPOLARIZED MRI PHANTOMS

Harlee Grace Harrison, B.S.

Advisory Professor: James Bankson, Ph.D.

Magnetic Resonance Imaging (MRI) is a powerful tool in the diagnosis of cancer due to its ability to provide good soft tissue contrast and image resolution without the use of ionizing radiation. The use of hyperpolarized pyruvate as a contrast agent for tumor metabolism during MR scans has the potential to provide information about tumor metabolism in vivo that is not available from traditional imaging measurements or any other method. Hyperpolarization is achieved through dynamic nuclear polarization. …

Tnf Signaling During Tissue Damage-Induced Nociceptive Sensitization In Drosophila, Juyeon Jo

Dissertations & Theses (Open Access)

Tumor necrosis factor (TNF) signaling is required for inflammatory nociceptive sensitization in both Drosophila and vertebrates. In Drosophila larval model of nociceptive sensitization, UV irradiation in results in epidermal apoptosis and thermal allodynia. TNF/Eiger is produced from dying epidermal cells and acts its receptor in nociceptive sensory neurons to induce thermal allodynia. Inhibition of TNF signaling results in attenuation of nociceptive sensitization whereas epidermal apoptosis still occurs in the absence of TNF. Major gaps in this model are the precise relationship between apoptotic cell death and production of TNF/Eiger, downstream signaling mediators for TNFR/Wengen, and target genes that alter nociceptive …

Novel Mechanisms Of Β-Adrenergic Signaling In Prostate Cancer Progression, Mohit Hulsurkar

Dissertations & Theses (Open Access)

Prostate cancer is the second leading cause of cancer death among American men. The American Cancer Society estimates that 180,890 men will be will be diagnosed with prostate cancer in 2016 in the USA. (http://www.cancer.org/cancer/prostatecancer/detailedguide/prostate-cancer-key-statistics). Androgen deprivation therapy (ADT) is the standard treatment for early stage prostate cancer. But most patients relapse with aggressive variants of prostate cancer, with survival time between 1-3 years. In order to develop cure for such aggressive variants of prostate cancer, our present understanding of the mechanisms underlying its progression needs to be advanced.

Recently, it has been found that activation of β-adrenergic signaling pathway …

The Impact Of Cortical State On Neural Coding And Behavior, Charles Beaman

Dissertations & Theses (Open Access)

The brain is never truly silent – up to 80% of its energy budget is expended during ongoing activity in the absence of sensory input. Previous research has shown that sensory neurons are not exclusively influenced by external stimuli but rather reflect interactions between sensory inputs and the ongoing activity of the brain. Yet, whether fluctuations in the state of cortical networks influence sensory coding in neural circuits and the behavior of the animal are unknown. To shed light on this issue, we conducted multi-unit electrophysiology experiments in visual areas V1 and V4 of behaving monkeys. First, we studied the …

The Power Of Reasoning: How Student Nurses Develop Confidence In Reasoning, Michael F. Brown

Dissertations & Theses (Open Access)

Background

Clinical Reasoning (CR) is the intellectual capacity to understand the value of patient data related to current knowledge, skills, and experiences within a dynamic domain of patient care with reflective analysis relating the new experience and understanding into new knowledge to be applied in future clinical situations. Poorly developed CR skills inhibit effective problem-solving abilities of nursing students producing levels of unexpected confusion and loss of confidence impeding their adaptability and effectiveness in dynamic healthcare environments. This study explored the effectiveness of human patient simulation (HPS) as an innovative method to facilitate the development of CR in undergraduate nursing …

Experiences Of Stress And Coping Over Time By Caregivers Of Stroke Survivors: A Mixed-Methods Approach, Fang Ye

Dissertations & Theses (Open Access)

Background/ Objectives: Caregivers of stroke survivors often experience physical and mental stress, decreased physical and emotional well-being, high burden of care, social isolation, and neglecting self-care. The majority of previous research studies have identified caregiver experiences during the first one-to-two years post stroke. Little is known about caregiver experiences beyond the first two years of the post- stroke recovery trajectory, indicating a need for longitudinal study of their experiences over time. Therefore, the objectives of this study were to 1) investigate caregiver experiences of stress and coping over 5-7 years post stroke using quantitative methods, and 2) explore through …

Investigating The Roles Of Δnp63 As A Suppressor Of Migration, Invasion, And Metastasis, Ramon E. Flores Gonzalez

Dissertations & Theses (Open Access)

Cancer is one of the leading causes of death and disease in the world. Considerable resources are spent to study and understand cancer, with the hope of developing new treatments and eventually cures that will help millions of people. Efforts to understand cancer are hindered by its inherent complexity and instability. Nonetheless, understanding the basics of tumor development and progression are the key to focused on studying the role of ΔNp63 in cancer, a p53 family member known to be involved in epithelial development, microRNA biogenesis, and stem cell maintenance. Using the strength of in vivo mouse models, we found …

Encapsulated Contrast Agent Markers For Mri-Based Post-Implant Dosimetry, Tze Yee Lim

Dissertations & Theses (Open Access)

Low-dose-rate prostate brachytherapy involves the implantation of tiny radioactive seeds into the prostate to treat prostate cancer. The current standard post-implant imaging modality is computed tomography (CT). On CT images, the radioactive seeds can be distinctively localized but delineation of the prostate and surrounding soft tissue is poor. Magnetic resonance imaging (MRI) provides better prostate and soft tissue delineation, but seed localization is difficult. To aid with seed localization, MRI markers with encapsulated contrast agent that provide positive-contrast on MRI images (Sirius MRI markers; C4 Imaging, Houston, TX) have been proposed to be placed adjacent to the negative-contrast seeds. This …

Potentially Inappropriate Medication Use In Older Patient With Breast And Colorectal Cancer, Meghan S. Karuturi

Dissertations & Theses (Open Access)

Our objective was to determine predictors of potentially inappropriate medication (PIM) use and its impact on outcomes (including ER visits, hospitalization, all cause death, and composite of three) in breast and colorectal cancer patients receiving chemotherapy. We used data from the SEER database linked to Medicare claims. Our cohort included patients ≥ 66 years diagnosed with of Stage II/III breast or colorectal cancer between 7/1/2007-12/31/2009. Baseline PIM was defined using the Drugs to Avoid in the Elderly list (DAE) or Beers criteria. Univariate and multivariable logistic regression were used to determine the associations of baseline PIMs with different covariates. Event-free …

Influences On Self-Care In Women With Heart Failure: A Pilot Study, Joy Corcione

Dissertations & Theses (Open Access)

Background: Heart Failure self-care becomes exceedingly difficult to perform as the disease progresses; therefore social support becomes important in facilitating heart failure self-care. Woman with heart failure represent a significant and growing vulnerable population. Women tend to have lower self-confidence in providing self-care, experience greater negative emotions, decreased social support, experience more adverse psychosocial factors affecting self-care and experience greater psychosocial adversity than do men. Self-care is vital in managing heart failure and social support greatly facilitates self-care behaviors.

Purpose: The purpose of this pilot study was to gain a deeper understanding about the sources of perceived social support and …

Treatment Recidivism In Adolescents With Mental Illness: A Focused Applied Medical Ethnography, Chukwudi C. Ekwemalor

Dissertations & Theses (Open Access)

Background

Treatment recidivism, described as frequent unplanned relapse readmissions, is a national problem predominant in adolescents with mental illness with significant socioeconomic consequences. Adolescents living with mental illness are a sub-culture of adolescence, the critical growth period of developmental and social transition from childhood to adulthood. The main triggers of treatment recidivism in this population are not fully understood from previous studies.

Purpose

The study purpose was to explore treatment recidivism with the following aims:

1. To illuminate treatment recidivism from the perspectives of recidivist adolescents with mental illness.

2. To describe the main factors that contribute to treatment recidivism …

Clinical Significance Of Homologous Recombination Deficiency Score Testing In Endometrial Cancer, Jean M. Hansen

Dissertations & Theses (Open Access)

Objectives: Homologous recombination deficiency (HRD) score is related to chemotherapy response in breast and ovarian cancers. The role of HRD is unknown in endometrial cancer. We examined the relationship between HRD score and survival in a cohort of endometrial cancer patients and with tumor growth using murine orthotopic models.

Methods: TCGA was queried to determine frequency and clinical significance of alterations in the HR pathway in endometrial cancer. 137 formalin-fixed paraffin-embedded endometrioid adenocarcinoma patient samples were tested for HRD score, microsatellite instability (MSI) and high mutation load (HML) using a next generation sequencing assay targeting the coding regions of 43 …

Implications Of Computational Cognitive Models For Information Retrieval, Joshua Caleb Goodwin

Dissertations & Theses (Open Access)

This dissertation explores the implications of computational cognitive modeling for information retrieval. The parallel between information retrieval and human memory is that the goal of an information retrieval system is to find the set of documents most relevant to the query whereas the goal for the human memory system is to access the relevance of items stored in memory given a memory probe (Steyvers & Griffiths, 2010).

The two major topics of this dissertation are desirability and information scent. Desirability is the context independent probability of an item receiving attention (Recker & Pitkow, 1996). Desirability has been widely utilized in …

Network Dynamics Of Visual Object Recognition, Mehmet C. Kadipasaoglu

Dissertations & Theses (Open Access)

Visual object recognition is the principal mechanism by which humans and many animals interpret their surroundings. Despite the complexity of neural computation required, object recognition is achieved with such rapidity and accuracy that it appears to us almost effortless. Extensive human and non-human primate research has identified putative category-selective regions within higher-level visual cortex, which are thought to mediate object recognition. Despite decades of study, however, the functional organization and network dynamics within these regions remain poorly understood, due to a lack of appropriate animal models as well as the spatiotemporal limitations of current non-invasive human neuroimaging techniques (e.g. fMRI, …

The Roles Of Malt1 In Nf-Κb Activation And Solid Tumor Progression, Deng Pan

Dissertations & Theses (Open Access)

The transcription factor NF-κB plays a central role in many aspects of biological processes and diseases, such as inflammation and cancer. Although it has been suggested thatNF-κB is critical in tumorigenesis and tumor progression, the molecular mechanism by which NF-κB is activated in solid tumor remains largely unknown. In the current work, we focus on growth factor receptor-induced NF-κB activation and tumor progression, including epidermal growth factor receptor (EGFR)-induced NF-κB in lung cancer and heregulin receptor (HER2)-induced NF-κB in breast cancer. We found that Mucosa-associated lymphoma translocation protein 1 (MALT1), also known as paracaspase, is required for EGFR-induced NF-κB activation …

Characterization Of Stem Cell Turnover In A Living Epithelial Bilayer, Elizabeth Sumner

Dissertations & Theses (Open Access)

Homeostatic maintenance of epithelia requires the renewal and replacement of old or dying cells while sustaining a functional barrier. Imbalance between cell production and elimination are hypothesized to underlie many pathological conditions. However, our knowledge of cell turnover within living tissues remains largely restricted to static images due to the limited ability to study epithelia in their native context. Here we report that clearance of damaged basal stem cells promotes compensatory proliferation of neighboring stem cells to maintain overall population numbers in a bilayered epithelium. Time-lapse imaging and electron microscopy experiments reveal that dying cells are rapidly cleared as nearby …

Attitudes Towards Prenatal Genetics Among Southeast And East Asian Women: A Qualitative Pilot Study, Ginger J. Tsai

Dissertations & Theses (Open Access)

From 2000-2010, the Asian population in the United States grew five times faster than the overall US population. As Asians become incorporated into the US health care system, it is important to recognize cultural differences that may arise between Asian patients and their health care providers. Prior studies show that cultural values influence genetic perceptions within Asian populations. The reputation of the family unit factors into decisions such as pregnancy termination and disclosure of family medical history, and the non-directive model of American genetic counseling conflicts with the historical Asian model of paternalistic health care. Previous studies also provide conflicting …

Accurate Mutation Annotation And Functional Prediction Enhance The Applicability Of -Omics Data In Precision Medicine, Tenghui Chen

Dissertations & Theses (Open Access)

Clinical sequencing has been recognized as an effective approach for enhancing the accuracy and efficiency of cancer patient management and therefore achieve the goals of personalized therapy. However, the accuracy of large scale sequencing data in clinics has been constrained by many different aspects, such as clinical detection, annotation and interpretation of the variants that are observed in clinical sequencing data. In my Ph.D thesis work, I mainly investigated how to comprehensively and efficiently apply high dimensional -omics data to enhance the capability of precision cancer medicine. Following this motivation, my dissertation has been focused on two important topics in …

Gsk3Beta-Mediated Ezh2 Phosphorylation Suppresses Methylation Of H3k27 And Ezh2’S Oncogenic Functions, How-Wen Ko

Dissertations & Theses (Open Access)

During the process of tumorigenesis, inactivation of tumor suppressors is a critical step. Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase and the enzymatic core subunit of polycomb repressive complex 2 (PRC2), promotes cell growth and migration through catalyzing trimethylation of histone H3 at Lys 27 (H3K27me3) and plays an important role in tumorigenesis. Its expression can be controlled by phosphorylation. However, the regulation of EZH2 activity by tumor suppressor kinase is not well understood. Glycogen synthase kinase 3 beta (GSK3b), a multifunctional serine/threonine kinase, is involved in many cellular processes. GSK3b also participates in neoplastic transformation, tumor development …

In Vivo Kinome Screen Reveals Non-Canonical Cdk-Driven Metabolic Adaptation In Brain Metastasis, Frank J. Lowery Iii

Dissertations & Theses (Open Access)

Brain metastasis, which frequently arises from breast cancer, lung cancer, melanoma, and colorectal cancer, remains a severely unmet medical need and its incidence continues to rise while treatment options remain palliative. To better understand the biology underlying its aggressive, incurable nature, I performed an unbiased in vivo kinome screen to identify potential driver kinases of experimental brain metastasis in a nude xenograft model using the human breast cancer cell line MDA-MB-231. Several of the kinase pools led to decreased brain metastasis-specific survival in nude mice, shortening survival time by up to 50% relative to controls. Targeted next-generation sequencing (NGS) was …

Insights Into Determinants That Contribute To Colonization, Virulence And Antibiotic Resistance In Enterococci, Maria Camila Montealegre

Dissertations & Theses (Open Access)

Enterococcus faecalis and Enterococcus faecium are increasingly common as causative agents of human infections, many of which are very difficult to treat due to multi-drug resistance. The work presented in the first part of this dissertation elucidates a mechanism for the regulation of pilus expression. I showed that ATT is the initiation codon of ebpA, the first gene of an operon that codes for the endocarditis and biofilm-associated pili (Ebp), a recognized virulence factor in E. faecalis. The presence of this rare start codon downregulates EbpA translation and protein levels, diminishing biofilm and binding abilities of …

Regulation Of The Escrt Function Of Alix, Sheng Sun

Dissertations & Theses (Open Access)

The ESCRT (endosomal sorting complex required for transport) is an evolutionary conserved membrane remodeling machinery that performs membrane invagination and abscission. ALIX is a widely expressed adaptor protein that is critically involved in three classical ESCRT-mediated processes, including MVB (multivesicular body) sorting, cytokinetic abscission and retroviral budding. Previous studies have demonstrated that ALIX involvement in these ESCRT-mediated processes requires ALIX interaction with the ESCRT-III component CHMP4 as well as a cargo protein. However, the native form of ALIX contains a default intramolecular interaction between N-terminal Bro1 domain and C-terminal PRD (proline-rich domain), leading to a closed conformation of ALIX that …

Nipt Results Indicative Of Maternal Neoplasms: Genetic Counselors' Preferences And Attitudes, Meagan E. Giles

Dissertations & Theses (Open Access)

Performing non-invasive prenatal testing (NIPT) on a pregnant woman with a chromosomally abnormal neoplasm may incidentally lead to the diagnosis of cancer due to the coexistence of circulating tumor and placental DNA. Published information regarding NIPT’s accuracy for neoplasm screening is limited, and guidance for patient management is currently lacking. This challenges clinicians’ ability to counsel patients regarding the implications of these results, which often is the responsibility of a genetic counselor. Over three hundred board-eligible/certified genetic counselors were surveyed regarding their awareness, preferences, and attitudes towards NIPT’s ability to indicate maternal neoplasms. Despite 95% of this cohort being aware …

No Difference In Health Related Quality Of Life Between Therapeutic Options For Type 1 Gaucher Disease, Victoria Wagner

Dissertations & Theses (Open Access)

Type 1 Gaucher disease (GD) is the most common lysosomal storage disorder. Previously, treatment for GD was limited to intravenous enzyme replacement therapy (ERT). ERT reduces symptoms and increases health­related quality of life (HRQoL) in people with this condition. In 2014, oral substrate reduction therapy (SRT) was approved for type 1 GD treatment. Although both therapies alleviate disease symptoms, effects of SRT on HRQoL and preferences for therapy are not well established. Electronic surveys were administered to adults with type 1 GD. HRQoL was scored with the Short Form­36 Version 2 ® Health Survey and descriptive statistics were used to …

Patient Perception Of Negative Non-Invasive Prenatal Testing Results, Ann Theresa Wittman

Dissertations & Theses (Open Access)

Non-invasive prenatal testing (NIPT) uses cell-free fetal DNA to assess for fetal aneuploidy during pregnancy. NIPT has higher detection rates and positive predictive values than previous methods; however, NIPT is not diagnostic. Studies suggest patients may underestimate the limitations of prenatal screening. Therefore, we conducted a prospective cross-sectional study of ninety-four women from genetic counseling clinics in Houston, Texas to assess patient understanding of the residual risk for aneuploidy after receiving a negative NIPT. The majority of participants (66%) understood the residual risk for Down syndrome following negative NIPT; however, 34% of participants indicated that negative NIPT completely eliminated the …