3,628 research outputs found

    Pathophysiological role and therapeutic potential of extracellular vesicles in cancer

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    Extracellular vesicles (EVs) are nanosized lipid bilayer vesicles that are endogenously generated through various biogenesis pathways within most cellular entities. Subsequently, they are released into the extracellular milieu to facilitate intercellular communication. They are composed of diverse bioactive molecules with important roles in physiological and pathological states. Over the past few decades, the therapeutic potential of EVs has garnered significant interest in the drug delivery field. However, deepened understanding of EV biology and further technological advances are needed to bridge the gap between research and clinical translation. In this thesis, we address these challenges and investigate EVs as novel biomedical agents. EVs are crucial components of physiological processes and disease development. Sensitive visualisation techniques are needed to better understand their function as therapeutic agents. In paper I, a bioluminescent labelling system was developed to track EVs in vitro and in vivo. The system uses genetic modifications to enable the encapsulation of sensitive luciferase-variants in EVs. The system was used in vivo to enable highly sensitive detection of EV distribution pattern. Exogenously administered EVs were found to rapidly distribute within different organs, with a preference for the spleen, lung, and liver. In addition to endogenously engineered EVs for in vivo tracking, exogenously engineered EVs can be utilised as promising drug delivery platforms. However, cargo loading is often insufficient, requiring improved EV loading approaches. In paper II, we developed an optimised cargo loading method using electroporation. An optimised protocol was designed to load EVs with doxorubicin, which increased cargo loading, EV recovery, and drug potency by 190-fold over free doxorubicin. Owing to their potential to cross biological barriers, transport bioactive cargo, and targetability, EVs can be exploited as delivery vehicles for targeting of therapeutics. EVs were used as delivery vectors in paper III by coating their surfaces with an Fc domain-specific antibodybinding moiety. These Fc-EVs were then decorated with various IgG antibodies and targeted to cells of interest. In vitro and in vivo antibody targeting studies showed the broad potential of this technology for cancer therapy. The platform efficiently targeted EVs to cancer cells, including HER2 and PD-L1 positive cells. As proof of concept, Fc-EVs with PD-L1 antibody accumulate in tumour tissue and, when loaded with doxorubicin, reduce tumour burden, and increase survival in melanoma-bearing mice. Despite significant EV engineering advances, we have a limited understanding of the biology of tumour-derived extracellular vesicles (tEVs). In paper IV, we investigated the role of in vitrogenerated melanoma-derived EVs as indirect communicators in tumour-induced haematopoiesis dysregulation. The tEVs, which contain high levels of angiogenic factors like VEGF, osteopontin, and tissue factor, were found to cause splenomegaly, extramedullary haematopoiesis, expansion of splenic immature erythroid progenitors, reduced bone marrow cellularity, medullary expansion of granulocytic myeloid suppressor cells, and anaemia in syngeneic mice. These findings suggest that tEVs dysregulate haematopoiesis during the immune escape phase of cancer immunoediting, making them potential targets for overcoming immune evasion and restoring normal haematopoiesis. To summarise, the tools generated in this thesis, including the ability to detect EVs in vivo, effective cargo loading, display antibody binding moieties on EV surfaces for targeting, and understanding the pathophysiological role of tEVs, contribute to the advancement of EVs for biomedical purposes, and clinical translation down the line

    CANCER TREATMENT BY TARGETING HDAC4 TRANSLOCATION INDUCED BY MICROSECOND PULSED ELECTRIC FIELD EXPOSURE: MECHANISTIC INSIGHTS THROUGH KINASES AND PHOSPHATASES

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    Epigenetic modifications, arising from sub-cellular shifts in histone deacetylase (HDAC) activity and localization, present promising strategies for diverse cancer treatments. HDACs, enzymes responsible for post-translational histone modifications, induce these epigenetic changes by removing acetyl groups from ε-N-acetyl-lysine residues on histones, thereby suppressing gene transcription. Within the HDAC group, class IIa HDACs are notable for their responsiveness to extracellular signals, bridging the gap between external stimuli, plasma membrane, and genome through nuclear-cytoplasmic translocation. This localization offers two significant mechanisms for cancer treatment: nuclear accumulation of HDACs represses oncogenic transcription factors, such as myocyte-specific enhancer factor 2C (MEF2C), triggering various cell death pathways. Conversely, cytoplasmic HDAC accumulation acts similarly to HDAC inhibitors by silencing genes. My dissertation introduces an innovative approach for glioblastoma and breast cancer treatment by investigating the application of microsecond pulsed electric fields. It particularly focuses on HDAC4, a class IIa HDAC overexpressed in these cancers. Beyond demonstrating HDAC4 translocation, my research delves into the intricate roles of kinases and phosphatases, shedding light on the underlying factors governing HDAC4 translocation

    Impact of the Increased Use of Telehealth on Health Care Management and Administration: The Case of New Care Management Practices

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    The COVID-19 pandemic has brought unprecedented challenges to healthcare systems worldwide, forcing them to adapt and implement alternative modes of healthcare delivery quickly. Telehealth, the delivery of healthcare services through telecommunication technologies, has become crucial in providing continuous care while reducing the risk of virus transmission. This qualitative study aimed to explore healthcare managers\u27 perceptions of the use of telehealth and its impact on healthcare practices during the pandemic, particularly in terms of provision and quality control. A purposive sample of 10 healthcare managers from different healthcare settings in the United States participated in semi-structured interviews conducted via video conferencing. The interviews were transcribed and analyzed using thematic analysis. The findings revealed six overarching themes: (1) perceived benefits of telehealth, including increased accessibility, convenience, and efficiency; (2) challenges and limitations of telehealth; (3) role of telehealth in shaping healthcare practices; (4) implications for quality control, including the need for standardization, training, and evaluation measures; (5) leadership and innovation in telehealth; and (6) future of telehealth in healthcare management. This study provides insights into how healthcare managers perceive the use of telehealth and how it shapes healthcare practices during the COVID-19 pandemic. The findings suggest that telehealth can potentially improve healthcare provision and quality control, but its implementation requires addressing challenges and limitations and adapting to evolving healthcare needs. Future research can build on these findings by exploring the perspectives of other stakeholders, such as healthcare providers and patients, and examining the long-term effects of telehealth on healthcare practices

    Effects of municipal smoke-free ordinances on secondhand smoke exposure in the Republic of Korea

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    ObjectiveTo reduce premature deaths due to secondhand smoke (SHS) exposure among non-smokers, the Republic of Korea (ROK) adopted changes to the National Health Promotion Act, which allowed local governments to enact municipal ordinances to strengthen their authority to designate smoke-free areas and levy penalty fines. In this study, we examined national trends in SHS exposure after the introduction of these municipal ordinances at the city level in 2010.MethodsWe used interrupted time series analysis to assess whether the trends of SHS exposure in the workplace and at home, and the primary cigarette smoking rate changed following the policy adjustment in the national legislation in ROK. Population-standardized data for selected variables were retrieved from a nationally representative survey dataset and used to study the policy action’s effectiveness.ResultsFollowing the change in the legislation, SHS exposure in the workplace reversed course from an increasing (18% per year) trend prior to the introduction of these smoke-free ordinances to a decreasing (−10% per year) trend after adoption and enforcement of these laws (β2 = 0.18, p-value = 0.07; β3 = −0.10, p-value = 0.02). SHS exposure at home (β2 = 0.10, p-value = 0.09; β3 = −0.03, p-value = 0.14) and the primary cigarette smoking rate (β2 = 0.03, p-value = 0.10; β3 = 0.008, p-value = 0.15) showed no significant changes in the sampled period. Although analyses stratified by sex showed that the allowance of municipal ordinances resulted in reduced SHS exposure in the workplace for both males and females, they did not affect the primary cigarette smoking rate as much, especially among females.ConclusionStrengthening the role of local governments by giving them the authority to enact and enforce penalties on SHS exposure violation helped ROK to reduce SHS exposure in the workplace. However, smoking behaviors and related activities seemed to shift to less restrictive areas such as on the streets and in apartment hallways, negating some of the effects due to these ordinances. Future studies should investigate how smoke-free policies beyond public places can further reduce the SHS exposure in ROK

    The Relationship Between Customers’ Satisfaction and Trust in the Global Supply Chain and Profitability

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    The inability to meet customer demands and expectations impacts an organization’s profitability. Understanding and meeting customer needs are critical for the financial success of business owners. Grounded in the theory of constraints, the purpose of this quantitative ex post facto study was to examine the relationships between customers’ satisfaction and trust in the supply chain and profitability. Secondary data (n = 121) were collected from the Elsevier Research Database using archival data collected from an automotive factory. Data were analyzed using multiple linear regression, and the results were statistically significant, F (2, 118) = 264.347, p \u3c .001, R2 = .90. In the final model, both predictor variables were significant, customers’ satisfaction: mean wait time (t = 22.991, p \u3c .001, β = 16.23); and customers’ trust: minimum stock level (t = 7.306, p \u3c .001, β = .118). A key recommendation is for business leaders to satisfy customers and gain their trust by creating sufficient inventory stocking levels and improving replenishment timeframes that meet customers’ supply chain demands. The implications for positive social change include the opportunity for supply chain managers to develop an effective supply chain that may contribute to the quality of service that promotes success in regional markets, sustain growth, and allows for social development among the local community workforces

    Introduction to Psychology

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    Introduction to Psychology is a modified version of Psychology 2e - OpenStax

    ENGINEERING HIGH-RESOLUTION EXPERIMENTAL AND COMPUTATIONAL PIPELINES TO CHARACTERIZE HUMAN GASTROINTESTINAL TISSUES IN HEALTH AND DISEASE

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    In recent decades, new high-resolution technologies have transformed how scientists study complex cellular processes and the mechanisms responsible for maintaining homeostasis and the emergence and progression of gastrointestinal (GI) disease. These advances have paved the way for the use of primary human cells in experimental models which together can mimic specific aspects of the GI tract such as compartmentalized stem-cell zones, gradients of growth factors, and shear stress from fluid flow. The work presented in this dissertation has focused on integrating high-resolution bioinformatics with novel experimental models of the GI epithelium systems to describe the complexity of human pathophysiology of the human small intestines, colon, and stomach in homeostasis and disease. Here, I used three novel microphysiological systems and developed four computational pipelines to describe comprehensive gene expression patterns of the GI epithelium in various states of health and disease. First, I used single cell RNAseq (scRNAseq) to establish the transcriptomic landscape of the entire epithelium of the small intestine and colon from three human donors, describing cell-type specific gene expression patterns in high resolution. Second, I used single cell and bulk RNAseq to model intestinal absorption of fatty acids and show that fatty acid oxidation is a critical regulator of the flux of long- and medium-chain fatty acids across the epithelium. Third, I use bulk RNAseq and a machine learning model to describe how inflammatory cytokines can regulate proliferation of intestinal stem cells in an experimental model of inflammatory hypoxia. Finally, I developed a high throughput platform that can associate phenotype to gene expression in clonal organoids, providing unprecedented resolution into the relationship between comprehensive gene expression patterns and their accompanying phenotypic effects. Through these studies, I have demonstrated how the integration of computational and experimental approaches can measurably advance our understanding of human GI physiology.Doctor of Philosoph

    Funktionelle Herzklappen-Stent Designs für zukünftige autologe, transkatheter Klappenprothesen in pulmonaler Position

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    Background Transcatheter pulmonary valve replacement (TPVR) has asserted its position as a cornerstone in cardiology and become a nonsurgical alternative for patients with a dysfunctional right ventricular outflow tract (RVOT), demonstrating excellent early and late clinical outcomes. Short- and long-term complications of TPVR include stent fracture and migration, coronary compression, and valve regurgitation. Objective The purpose of this study is to describe methodology for developing Nitinol stents by conducting a computational design and finite element analysis in conjunction with 3D reconstruction of animal cardiac CT for TPVR. Methods 3D cardiac CT reconstruction was achieved using 3D Slicer, from which the RVOT + pulmonary artery (PA) was exported for blood flow simulation and hoop force acquisition with the stents. Functional stents were designed using Autodesk Fusion 360 and divided into three morphological geometries: group 1–straight tubular stents, group 2–corollaceous stents, and group 3–corollaceous stents with an elliptic geometry. Stent simulations for stent life and radial force, and the hoop force of the stent during expansion with the RVOT+PA model were obtained in Ansys. The blood flow simulation of RVOT+PA was performed using Ansys with the velocity-based coupled solver. Results 3D cardiac CT reconstructions were obtained in STL format, from which the right ventricle (RV) +PA model was performed for the blood flow simulation and the hoop force was obtained with the stents. Twelve functional stents were successfully designed and exported in SAT and STP formats for simulation. All stent life (Times)/radial force (N) were achieved: Group 1 comprised the stents DGS 3 (3219.2/1.88E+05), DGS 5 (16406/1.94E+05), DGS 7 (1.00E+06/1.89E+05), DGS 8B (0/3.74E+05), DGS-10B (8370.1/2.41E+05), DGS 12D (1.00E+06/2.41E+08); Group 2 comprised the stents DGS 8A (0/3.60E+05), DGS 9A (0/3.60E+05), DGS 10A (46093/2.28E+05), DGS 12C (2.50E+005/1.69E+05); Group 3 comprised the stents DGS 12A (1.00E+06/2.38E+08), DGS 12B (54509/2.20E+05). Hoop force (N) was obtained from the 12 stents: Group 1–DGS 5 (57802), DGS 7 (54647), DGS 8B (53248), DGS 10B (56650), DGS 12D (46297). Group 2–DGS 8A (50490), DGS 9A (60393), DGS 10A (23639), DGS 12C (29802). Group 3–DGS 12A (16368), DGS 12B (16368). The RV+PA blood flow simulation demonstrated that the anterior part of the PA wall had the largest shear force. Conclusions DGS 12C, DGS 12D, DGS 10A, DGS 10B, DGS 7, and DGS 5 can be subsequently tested in vitro. Autologous pulmonary valves could be sutured onto the functional stents to maintain their original geometry prior to implantation. Pre-implantation 3D CT reconstruction and stent simulation can be performed for better evaluation and visualization. The RV+PA blood flow simulation may serve as a significant input for the design of stents and pulmonary valve to determine the shear force throughout the cardiac cycle.Hintergrund Der katheterbasierte Pulmonalklappenersatz ist ein Eckpfeiler der Kardiologie und bietet zudem eine nicht-chirurgische Alternative für die Behandlung funktionsgestörter rechtsventrikulärer Ausflusstrakte oder bioprothetischer Klappen mit hervorragenden frühen und späten klinischen Ergebnissen. Kurz- und langfristige Komplikationen von TPVR umfassen Stentfraktur/-migration, Komprimierung der Koronararterien und Klappeninsuffizienz. Ziel Ziel dieser Studie ist es, die Methodik und das Konzept für Nitinol-Stents mithilfe rechnerischer Entwürfe und Finite-Elemente-Analysen anhand von 3D-Rekonstruktionen kardialer CT-Untersuchungen in Tieren für die Anwendung von TPVR zu beschreiben. Methoden Die 3D-Rekonstruktion der CT-Untersuchungen erfolgte mit der Software 3D Slicer, aus der die RVOT und Pulmonalarterie (PA) in Verbindung mit den Stents für die Blutflusssimulation und die Umfangsspannung exportiert wurde. Die funktionellen Stents wurden mit Fusion 360 entworfen und danach in die Formate SAT und STP exportiert. Simulationen für die Lebensdauer und Radialkraft sowie für die Umfangsspannung der Stents bei der Freisetzung mit dem RVOT+PA-Modell wurden in Ansys berechnet. Die Blutflusssimulation von RVOT+PA wurde in Ansys mit dem geschwindigkeitsbasierten gekoppelten Solver durchgeführt. Ergebnisse Zwölf funktionelle Stents wurden mithilfe von Fusion 360 generiert. SAT- und STP-Dateien wurden zur Simulation in Ansys exportiert. 3D Kardio-CT-Rekonstruktionen wurden mithilfe im STL-Format kreiert, aus dem das RVOT+PA-Modell des Prä-CT ausgewählt wurde, um die Blutflusssimulation durchzuführen und die Ringkraft der Stents zu erhalten. Die Lebensdauer (Anzahl) und Radialkraft (N) der Stents wurden wie folgt berechnet: DGS-3 (3219.2/1.88E+05), DGS-5 (16406/1.94E+05), DGS-7 (1.00E+06/1.89E+05), DGS-8A (0/3.60E+05), DGS-8B (0/3.74E+05), DGS-9A (0/3.60E+05), DGS-10A (46093/2.28E+05), DGS-10B (8370.1/2.41E+05), DGS-12A (1.00E+06/2.38E+08), DGS-12B (54509/2.20E+05), DGS-12D (1.00E+06/2.41E+08), DGS-12C (2.50E+005/1.69E+05). Die jeweilige Umspannungskraft (N) wurde wie folgt berechnet: DGS-5 (57802), DGS-7 (54647), DGS-8A (50490), DGS-8B (53248), DGS-9A (60393), DGS-10A (23639), DGS-10B (56650), DGS-12A (16368), DGS-12B (16368), DGS-12C (29802), DGS-12D (46297). Die RV+PA-Blutflusssimulation zeigte, dass der vordere Teil der PA-Wand die größte Scherkraft aufwies. Schlussfolgerungen DGS-12C, DGS-12D, DGS-10A, DGS-10B, DGS-7 und DGS-5 können nachfolgend in vitro getestet werden. Autologe Pulmonalklappen können zur Erhaltung der ursprünglichen Geometrie vor der Implantation auf funktionelle Stents aufgenäht werden. Vor der Implantation können Kardio-CT 3D-Rekonstruktion und Stentsimulationen zur besseren Bewertung und Visualisierung durchgeführt werden. Die Blutflusssimulation von RVOT+PA kann einen bedeutsamen Beitrag zur Gestaltung von Stents und Pulmonalklappen leisten, um die Scherkraft während des gesamten Herzzyklus zu erhalten
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