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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Physicians‟ information practices : a case study of a medical team at a Teaching Hospital

Isah, Esther Ebole January 2012 (has links)
This thesis is a user study within library and information science on participatory practices of a professional group in work activity. This has been investigated only to a minor extent in previous library and information science research. The qualitative empirical focus alternates between physicians‟ engagements in work practice and workplace learning within patient care. The overall research problem was to learn how people in workplaces interacted with information that was embedded, intricately intertwined, and tightly bound to the ongoing routines of their everyday work. This thesis aims at understanding information practices of professionals in occupational settings as exemplified by a team of physicians in a Nigerian teaching hospital. In this thesis, the focus was on the collective work activity, and the specific goals identified include how physicians interact and make meaning in the context of the social activities in the workplace, how professionals individually or collectively gather, understand, produce, share and use information, and how workplace learning influences information practices. Information practices are viewed as sociocultural practices that occur inside other practices. The thesis focuses on a nuanced, contextualized understanding of the interplay between the participating actors in activity, the activity per se, and the intermediary role of tools and artefacts. The epistemological point of departure is the sociocultural perspective that emphasizes the dynamic interdependence of the individual with the social and collective development focusing on mediation through tools and artefacts in cultural, institutional, and historical situations. I have chosen cultural-historical activity theory and the practice theories to analyse the dynamic processes in the context of patient care. Their underlying principles guided the empirical study, facilitating extrapolations and illustrations in the analysis. The cultural-historical activity theory was used to understand contextual issues that influence information practices in work activity: the object and subject of activity, division of labour, rules and norms, community, tools and artefacts, as well as the activity system itself and the hierarchical structure of the activity. Theories and concepts employed from a practice perspective on learning were considered useful for understanding the participatory modes in workplace and the influence of social learning communities on diverse information processes. In so doing, the study strives to provide a holistic understanding of information practices, workplace learning, and the relationships between them.The empirical data was gathered through a qualitative case study that lasted over a period of two years. Direct observation was the dominant data collection technique 5 used throughout the preliminary and main empirical studies to capture physicians‟ information practices and experiences. The observation focused on the Clinical Pharmacology and Therapeutics (CPT) team‟s encounters with patients; the interactions they had amongst themselves, and events and situations surrounding patient care. During the main study, other data collection techniques were employed alongside the observation method. In-depth open-ended interviews were conducted with 17 physicians and 9 non-physicians who were selected to provide rich and varied descriptions of the phenomena under study. The interview time totalled at 1,535 minutes. Physical artefacts were another data collection technique employed: 30 patients‟ medical records were assessed during the empirical study. Finally, informal interactions in the research setting were an additional data collection technique used continuously throughout the two empirical periods. The results were analyzed through a combination of inductive and deductive methods of analysis. There are four parts to the empirical results in this thesis. In the first, contextual elements that showed how work environment can be an influencing factor in the information practices of a professional group are described from the perspective of cultural historical activity theory. In the second part, the nature of information access in the real-world information environment was portrayed. It was found that information sources and strategies contributed to the overarching goal of restoring patient health to normalcy. The information sources and strategies were also found useful for mediating the information environment both subjectively and intersubjectively. An equally important result concerns the authority issues related to information sources and strategies. In the third part, available tools and artefacts were presented as useful information aids that also played a mediating role. Tools were categorised into physical tools and language. Language was categorized according to the social situations or classes of speakers. The case notes were seen as useful artefact and occupied a central niche in the studied work activity. These tools and artefacts enabled affordances around which social practices were built on in the work activities. In the last part of the results, various information practices that mirror the participatory practices rather than those of isolated individuals are highlighted. Six dimensions made up and covered the most vital spectrum of the information processing: information gathering, meaning making, information sharing, information use, reading, and documentation. Furthermore, the study revealed that learning took place simultaneously with the work activity and that it influenced information practices at the same time. / <p>Academic dissertation for the Degree of Doctor of Philosophy in Library and Information Science at the University of Borås to be publicly defended on Friday 19 October 2012 at 13.00 in lecture room D 211, University of Borås, Allégatan 1, Borås.</p>
22

A MULTIMETHOD APPROACH TO IDENTIFY FACTORS AND IMPROVE THE PROCESS OF DEPRESCRIBING ANTICHOLINERGICS IN OLDER ADULTS.

Khalid Ahmed Alamer (15353419) 29 April 2023 (has links)
<p>  </p> <p>Polypharmacy in older adults presents several challenges, such as suboptimal therapeutic outcomes and increased adverse effects. Deprescribing, a clinically supervised process of decreasing dosage or stopping the medication when risks outweigh benefits, has emerged as one possible solution to these problems. However, the literature describing deprescribing intervention frameworks is heterogenous regarding targeted medications to deprescribe, population characteristics, clinical settings, and measured outcomes. This dissertation utilizes Linsky et al.'s deprescribing conceptual model, which details factors influencing decisions regarding initiating deprescribing interventions and their direct impact on the process. </p> <p>This dissertation utilizes a multimethod approach to investigate factors that facilitate and improve the deprescribing of anticholinergic medications for older adults, addressing gaps in this population's anticholinergic medication use. The three studies included in this dissertation provide a comprehensive understanding of deprescribing anticholinergic medications for this population, each contributing unique insights and results. </p> <p>The first study explores the feasibility of in-person and remote Home Medication Inventory Method (HMIM) approaches to evaluate over-the-counter (OTC) and prescription medication possession and use, including anticholinergics. Results demonstrate that both methods can accurately assess anticholinergic medication usage patterns, providing healthcare providers with reproducible methods and detailed medication profiles to make informed deprescribing decisions based on complete medication lists.</p> <p>The second study examined the intertwined roles of social determinants of health and health beliefs in predicting older adults' self-reported deprescribing behaviors, proposing the Deprescribing Health Belief Model (DeRx-HBM) framework that can be utilized for these efforts. These results emphasize the importance of considering these elements when creating a patient-centric and culturally sensitive intervention since they significantly shape deprescribing behaviors.</p> <p>In the third study, we explored the use of a symptom-specific scale for measuring the symptom burden in older adults during the deprescribing of anticholinergic medications prescribed for urinary incontinence, depression, and pain management. This research introduces a validated scale for assessing anticholinergic symptom burden prior to, throughout, and following the deprescribing attempt. The implementation of this scale has the potential to enhance the reproducibility and standardization of deprescribing decisions. Furthermore, it can improve communication between healthcare professionals and patients, as well as monitor the effectiveness of interventions during and after the deprescribing process.</p> <p>Collectively, these studies provide invaluable insights into factors influencing deprescribing decisions, obstacles to implementing deprescribing practices, and potential strategies to optimize medication management in older adults. The major takeaway from these studies is that addressing these factors leads to more informed decisions among healthcare professionals and patients - potentially leading to improved patient outcomes, ensure the ongoing effectiveness of deprescribing initiatives among older adults, and the promotion of health equity throughout the deprescribing process.</p>
23

Mechanisms of microRNA-mediated regulation of the rapid delayed rectifier potassium current, IKr, during sustained beta-adrenergic receptor stimulation

Enoch Amarh (17598138) 12 December 2023 (has links)
<p dir="ltr"><b>Background</b></p><p dir="ltr">Heart failure (HF) is a chronic clinical syndrome characterized by symptoms including breathlessness, fatigue, swelling of the ankles, and signs such as edema pulmonary crackles etc. During HF, pathogenic mechanisms including hemodynamic overload, ventricular remodeling, aberrant calcium handling, excessive neurohormonal stimulation contribute to the worsening and progression of the condition. Ventricular arrhythmias are the common cause of sudden cardiac death (SCD) in HF patients.</p><p dir="ltr">Hyperactivation of the sympathetic nervous system (SNS), a characteristic of HF, causes an increase in circulating catecholamines which becomes detrimental to-adrenergic receptors (-AR) leading to signaling dysfunction, and decrease in contractility and the ionotropic reserve. Expression of calcium/calmodulin-dependent protein kinase II (CaMKII), a downstream effector of-AR and a key regulator of calcium homeostasis, has been shown to be enhanced in HF. CaMKII-mediated mechanisms have been demonstrated to contribute to cardiac remodeling, arrhythmias by pathological regulation of ion channels, and contractile dysfunction.</p><p dir="ltr">The human ether-a-go-go related gene (hERG) encodes the pore-forming subunit of the voltage-gated potassium channel that conduct the rapid component of the delayed rectifier potassium current, <i>I</i><sub>Kr</sub>. The gating kinetics of <i>I</i><sub>Kr </sub>makes it a crucial determinant of the duration of the plateau phase of atrial and ventricular action potential (AP). Reduced <i>I</i><sub>Kr</sub> density due to loss-of-function mutations or pharmacological blockage of hERG channels precipitate arrhythmias. Downregulation of <i>I</i><sub>Kr</sub> density and protein have been reported in HF. Recent studies suggest that microRNAs (miRNAs) are involved in pathological downregulation of hERG.</p><p dir="ltr">miRNA are small non-coding RNAs of approximately 22 nucleotides in length that function as gene expression regulatory elements by repression translation. Aberrant miRNA expression has associated with cancer, cardiovascular, autoimmune, and inflammatory disorders.</p><p dir="ltr"><b>Objective</b></p><p dir="ltr">The overarching objective of this study is to investigate the mechanisms of CaMKII-mediated regulation of hERG function, including assessment of an interplay with miR-362-3p during sustained β-AR stimulation. In Specific Aim 1, the effect of CaMKII activation through sustained β-AR stimulation on hERG function and miR-362-3p expression will be assessed. The mechanism of miR-362-3p upregulation will be evaluated in Specific Aim 2, and in Specific Aim 3, the interactome of miR-362-3p and binding sites will be characterized and predicted, respectively.</p><p dir="ltr"><b>Methods</b></p><p dir="ltr">Whole-cell, voltage clamp electrophysiology experiments were performed in HEK 293 cells stably expressing hERG (hERG-HEK) and both hERG and wild-type CaMKIIδ<br>(hERG/CaMKII-HEK) following treatment with isoproterenol for 48 hours, and after transfection with miR-362-3p. The effect of CaMKII activation on miR-362-3p was assessed using real-time quantitative polymerase chain reaction (RT-qPCR). Total RNA was isolated 48 hours after isoproterenol treatment and the TaqMan assay was used to reverse transcribe and analyze miR-362-3p expression. Cells were transfected with cJun siRNA and precursor miR-362-3p to assess the role of cJun miR-362-3p upregulation during sustained β-AR stimulation with isoproterenol. The interactome of miR-362-3p was assessed in both cell lines using enhanced crosslinking immunoprecipitation (eCLIP) assay. miR-362-3p binding sites were predicted using RNAStructure Duplexfold after identification of miR-362-3p chimeric molecules from eCLIP experiment. Interaction analysis was performed using GeneMania in Cytoscape to identify genes that were potentially downregulated by miR-362-3p and been reported to interact with hERG.</p><p dir="ltr"><b>Results</b></p><p dir="ltr">In Specific Aim 1, the effect of sustained β-AR stimulation on hERG currents and endogenous miR-362-3p was assessed in hERG-HEK and hERG/CaMKII-HEK cells. Using whole-cell voltage clamp electrophysiology, we demonstrated that 48 hours treatment with 100 nM isoproterenol reduced hERG currents in hERG/CaMKII-HEK cells (p = 0.032) but had no effect on the voltage dependence of activation (p = 0.61) relative to control vehicle. Isoproterenol treatment for 48 hours, however, had no effect on hERG currents (p = 0.58) and the voltage dependence of activation (p = 0.99) in hERG-HEK cells. The effect of sustained isoproterenol treatment on miR-362-3p was also assessed using RT-qPCR. In hERG/CaMKII cells, 48 hours isoproterenol treatment increased miR-362-3p expression (2.3 folds; p = 0.038) relative to control vehicle. hERG/CaMKII-HEK cells were also treated with 500 nM KN-93 or its inactive analogue, KN-92, in an attempt to reverse CaMKII effect on miR-362-3p expression. Treatment with KN-93 decreased miR-362-3p expression (0.5-fold; p = 0.002) relative KN-92 treatment. Isoproterenol treatment had no effect on miR-362-3p expression in hERG-HEK cells (p = 0.38).</p><p dir="ltr">The regulatory mechanism of miR-362-3p expression was evaluated in Specific Aim 2. The role of an activator protein-1 (AP-1)-like sequence located at 98 base pairs upstream of miR-362-3p transcription start site was probed using siRNA inhibition of cJun, a central protein of the AP-1 complex, and deletion of the site sequence. The effect of exogenous miR-362-3p on hERG currents were first assessed. Precursor miR-362-3p decreased hERG currents (p = 0.003) compared to control plasmid. The effect of CaMKII overexpression was also assessed on exogenous miR-363-3p expression. Isoproterenol treatment in hERG/CaMKII-HEK cells transfected with precursor miR-362-3p increased mature miR-362-3p expression (0.029) compared to control vehicle treatment. Inhibition of cJun inhibition with cJun-specific siRNA decreased mature miR-362-3p expression (0.5-fold; p = 0.027) compared to scramble siRNA in hERG-HEK cells. In hERG-HEK cells transfected with mutated precursor miR-362-3p (AP-1-like site deleted), cJun inhibition with siRNA had no effect on miR-362-3p expression (p = 0.40).</p><p dir="ltr">The focus of Specific Aim 3 was to characterize the interactome of miR-362-3p as well as predict the miRNA response element (MRE) of its target mRNAs using enhanced crosslinking immunoprecipitation. A network analysis was also performed to identify miR-362-3p targets that have been reported to interact with hERG. Approximately 23% of miR-362-3p mRNA targets from the eCLIP assay have also been catalogued in miRNA database, TargetScanHuman, as miR-362-3p targets. miR-362-3p chimeric molecules with 853 unique targets, of which 75 were identified to interact with hERG through the network analysis. Four unique chimeric molecules between miR-362-3p and hERG mRNA were identified, but the interactions were non-canonical (located in the coding sequence of hERG and outside the seed region of miR-362-3p). Thirty five of the 75 miR-362-3p targets that were identified to interact had a chimeric read ≥ 3, a cutoff number indicating non-random chimeric formation. Using RNAStructure DuplexFold, miR-362-3p was predicted to form canonical binding with 12 of 35 mRNA targets. HSPA4, a heat shock protein involved in the maturation and trafficking of hERG, was identified in a canonical interaction (8-mer) with miR-362-3p.</p><p dir="ltr"><b>Conclusion</b>:</p><p dir="ltr">Sustained β-AR stimulation increases miR-362-3p expression and decreases hERG currents in CaMKII overexpressing cells. cJun mediates miR-362-3p upregulation by interacting with an AP-1-like sequence upstream of miR-362-3p transcription start site. Pathological regulation of <i>I</i><sub>Kr</sub> by CaMKII mediated by miR-362-3p during sustained-AR may contribute to increased risk of arrhythmias in states of increase catecholaminergic activity, such as HF.</p>
24

DESIGNING COMBINATION DRUG REGIMENS TO IMPROVE GLIOBLASTOMA CHEMOTHERAPY: A PHARMACOKINETIC PHARMACODYNAMIC MODELING APPROACH

Saugat Adhikari (11267001) 13 August 2021 (has links)
<p>Despite advancements in therapies, such as surgery, irradiation (IR) and chemotherapy, outcome for patients suffering from glioblastoma (GBM) remains fatal; the median survival time is only about 15 months. Even with novel therapeutic targets, networks and signaling pathways being discovered, monotherapy with such agents targeting such pathways has been disappointing in clinical trials. Poor prognosis for GBM can be attributed to several factors, including failure of drugs to cross the blood-brain-barrier (BBB), tumor heterogeneity, invasiveness, and angiogenesis. Development of tumor resistance, particularly to temozolomide (TMZ) and IR, creates a substantial clinical challenge.</p><p> </p><p>The primary focus of the work described herein was to develop a modeling and simulation approach that could be applied to rationally develop novel combination therapies and dose regimens that mitigate resistance development. Specifically, TMZ was combined with small molecule inhibitors that are either currently in clinical trials or are approved drugs for other cancer types, and which target the disease at various resistance signaling pathways that are induced in response to TMZ monotherapy. To accomplish this objective, an integrated PKPD modeling approach was used. A PK model for each drug was first defined. PK models were subsequently linked to a PD model description of tumor growth dynamics in the presence of a single drug or combinations of drugs. A key outcome of these combined PKPD models was tumor static concentration (TSC) curves of TMZ in combination with small molecule inhibitors that identify combination drug exposures predicted to arrest tumor growth. This approach was applied to TMZ in combination with abemaciclib (a dual CDK4/6 small molecule inhibitor) based on data from a published study evaluating abemaciclib (ACB) efficacy in combination with TMZ in a U87 GBM xenograft model. TSC was also constructed for TMZ in combination with RG7388 (MDM2 inhibitor) based on the data from an in-vivo study that evaluated effects on tumor growth suppression of these small molecule inhibitors in combination with TMZ in GBM 10 patient derived xenografts.</p><p>In GBM 43 mouse xenografts, emergence of resistance to TMZ treatment was identified. Thus, a resistance integrated PKPD model was developed to predict tumor growth kinetics after treatment with TMZ in GBM 43 tumors. Population PK models in immune deficient NOD.Cg-<em>Prkdc<sup>scid</sup> Il2rg<sup>tm1Wjl</sup></em>/SzJ (NSG) mice for TMZ and small molecule inhibitors (GDC0068/RG7112) were developed based on a combination of data obtained from an in-vivo study and published sources. Subsequently, PK models were linked to tumor volume data obtained from GBM 43 subcutaneous xenografts. Model parameters quantifying tumor volume dynamics were precisely estimated (coefficient of variation < 40%) compared to a base tumor growth inhibition model in GBM 43 that did not incorporate resistance development. Graphical diagnostics of the resistance incorporated PKPD tumor growth inhibition model demonstrated a superior fit compared to the base model, and accurately captured the emergence of resistance to the TMZ monotherapy treatment observed in the GBM 43 patient derived xenograft model.</p>
25

CELLULAR AND BEHAVIORAL CHARACTARIZATION OF δ-OPIOID RECEPTOR MEDIATED ß-ARRESTIN SIGNALING

Arryn T Blaine (13154670) 26 July 2022 (has links)
<p>The following thesis will focus on understanding the downstream behavioral effects of δORmediated β-arrestinsignaling. δORagonists have been implicated as effective targets for a variety of diseases, however detrimental side effects of opioid-targeting agonists limit their clinical use. δORagonists specifically can induce seizures, however the underlying mechanism contributing to this  behavior  is  unknown.  We  review  this  phenomenon  in  more  detail,  highlighting  current agonists known to induce seizures and potential circuits and pathways involved. Our work suggests β-arrestinsignaling  is  involved,  specifically β-arrestin2  mediated  signaling  may  be  largely contributing  to δORagonist-induced  seizure  behavior.  As  it  is  possible  the β-arrestinisoforms have unique roles in seizure behavior, we also analyzed methods in which to provoke β-arrestinisoform bias of δORtargeting compounds. Though the full mechanism relating δORagonists with seizures remains unknown, our work provides foundational detail of this behavior, implicating the importance of β-arrestinisoform signaling through δOR; allowing for future studies to full define this seizure pathway and develop δORsafer agonists.  </p>
26

A Proteomics Based Approach to Characterizing Subcutaneous Tissues

Eden Nichole Schipper (13174443) 29 July 2022 (has links)
<p>Biotherapeutic compounds such as monoclonal antibodies help millions of people worldwide.  Currently, one of the most popular ways to deliver these compounds is via subcutaneous (SC)  injection. While it is understood that SC drug delivery does change with respect to injection  location, it is not understood why, as how the composition of SC changes as a function of location  is unknown. In this study, liquid chromatography mass spectrometry was used to understand and  describe how the SC tissue space changes on a molecular level. SC tissue from three different  locations, belly, breast, and behind the ear, of Yucatan minipigs was harvested and analyzed to  understand if and how SC tissue changes when anatomical location changes. It was determined  that there were distinct differences between the proteins identified in the three anatomical  locations. These differences included differences in relative cell populations, indicating that  different anatomical locations of SC tissue have different functions. Additionally, an ex vivo human SC tissue model was used to identify a core human proteome, as well as determine  compositional differences between female and male SC tissues. This model was also compared to  the Yucatan minipig model to determine compositional similarities between all groups. Finally,  proteomics were also used to ascertain whether the mass of SC tissue used affected the proteomic  results of the sample. These results indicated that human SC identifies the same number of proteins  down to samples of 10mg. This information can be used to design a proteomic experiment that  uses core needle biopsies to determine what gauge needle should be used in a wide scale clinical  study characterizing the human SC proteome. </p>

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