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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.
161

Novel Approaches in Pancreatic Cancer Treatment: Bridging Mechanics, Cells, and Immunity

Imran, Khan Mohammad 04 January 2024 (has links)
The heterogeneity of pancreatic cancer renders many available general therapies ineffective holding the five-year survival rate close to 10% for decades. Surgical resection eligibility, resistance to chemotherapy and limited efficacy of immunotherapy emphasize the dire need for diverse and innovative treatments to combat this challenging disease. This study evaluates co-therapy strategies that combine non-thermal, minimally invasive ablation technology and targeted drug delivery to enhance treatment efficacy. Our research begins by uncovering the multifaceted potential of Irreversible Electroporation (IRE), a cutting-edge non-thermal tumor ablation technique. This study demonstrates IRE-mediated ability to trigger programmed necrotic cell death, induce cell cycle arrest, and modulate immune cell populations within the tumor microenvironment. This transformation from a pro-tumor state to a proinflammatory milieu, enriched with cytotoxic T lymphocytes and neutrophils. IRE-induced proinflammation in the tumor site renders immunologically "cold" tumor into immunologically "hot" tumor and holds significant promise of improving treatment efficacy. Notably, IRE-treated mice exhibited an extended period of progression-free survival, implying clinical potential. The transient nature of these effects suggests potential mechanisms of tumor recurrence highlighting the need for further studies to maximize the efficacy of IRE. Our mechanistic studies evaluated the IFN-STAT1-PD-L1 feedback loop as a possible reason for pancreatic tumor recurrence. Our data also suggest a stronger IFN-PD-L1 feedback loop compared to mammary, osteosarcoma and glioblastoma tumors rendering pancreatic cancer immunologically "cold". This study also investigates the use of histotripsy (a non-thermal, noninvasive, nonionizing ultrasound-guided ablation modality) to treat pancreatic cancer utilizing a novel immunocompromised swine model. We successfully generated human orthotopic pancreatic tumors in the immune deficient pigs, which allowed for consequent investigation of clinical challenges presented by histotripsy. While rigorous clinical studies are indispensable for validation, the promise of histotripsy offers new hope for patients. In parallel, we used our immunocompromised swine model of orthotopic pancreatic cancer to investigate the SonoTran® system, which employs ultrasound-activated oscillating particles to enhance drug delivery within hard-to-reach tumors. Our study demonstrates that SonoTran® significantly enhances the intratumoral penetrance of therapeutic agents, including commonly used chemotherapy drugs like paclitaxel and gemcitabine. Additionally, SonoTran® improved delivery of the anti-epidermal growth factor (EGFR) monoclonal antibody, cetuximab- which is frequently used in cancer immunotherapy. Together, our findings address challenges in the delivery of a range of therapeutics while simultaneously exposing challenges like off-target damage. In conclusion, this study presents a multifaceted approach to confront the complex characteristics of pancreatic cancer. Given the variations in patient response and the complexity of the disease, it is clear that a singular solution is unlikely. Our research, which combines IRE, histotripsy, and SonoTran®, to interrogate a promising array of tools to tackle different challenges to provide tailored treatments. In the ever-evolving landscape of pancreatic cancer therapy, this research opens new avenues to investigate deeper into molecular mechanisms, co-therapy treatment options, future preclinical and clinical studies which eventually encourage the potential for improved patient outcomes. / Doctor of Philosophy / Pancreatic cancer is a formidable disease, known for its late-stage diagnosis and limited treatment options with a poor 5-year survival rate of ~10%. However, a promising frontier in the battle against this lethal disease has emerged through combining mechanical, cell based and immunotherapies to attack the cancer from multiple angles at once. In my PhD research, I explored novel approaches to transform the landscape of pancreatic cancer treatment. We began by investigating Irreversible Electroporation (IRE), a non-thermal method to ablate tumors. Beyond its known function of reducing tumor size, IRE initiated programmed necrotic cell death, halted tumor cell division, and triggered changes in the immune landscape within the tumor. In response to IRE treatment, the immune environment shifted from pro-tumor to proinflammatory state, showing potential for clinical use. Mice treated with IRE experienced extended cancer progression-free survival temporarily, followed by eventual relapse. During relapse, we found that immune cells reverted back to their original, pre- IRE treated state. This observation logically implies combining IRE and immune checkpoint inhibitors aimed towards maintaining the IRE-altered immunological environment. Next, we developed and used novel pig models that closely resemble human pancreatic cancer patients to test histotripsy, a first phase toward making histotripsy as a non-invasive treatment approach for pancreatic cancer. Use of orthotopic tumor in a large animal model and clinical device allowed us to expose some challenges of ultrasound guidance of histotripsy. Notably, the treatment results in partial ablation and a reduction in stroma materials, which play a role in the tumor's resistance to commonly used treatments. While rigorous clinical studies are needed for validation, this approach offers hope in the quest for innovative pancreatic cancer treatment. Another promising approach we investigated involves SonoTran® particles, ultrasound-activated oscillating particles that can increase drug absorption in a targeted fashion. Our study demonstrated increased concentrations of commonly used therapeutic agents within tumors through SonoTran®-facilitated delivery, providing an effective means to overcome drug delivery issues within pancreatic tumors. There is no one size fits all treatment to address the complexity of pancreatic cancer. The future of treatment lies in the integration of IRE, histotripsy and SonoTran® into clinical practice. In summary, this PhD research identified promising novel technologies and combinations of treatments for pancreatic cancer, reaffirming the importance of exploring innovative solutions to combat pancreatic cancer. The dynamic nature of the pancreatic tumor microenvironment underscores the importance of further research to extend the positive impacts of these treatments and improve tumor debulking.
162

The Role of Fusobacterium nucleatum in the Tumor Microenvironment

Gummidipoondy Udayasuryan, Barath 21 April 2022 (has links)
Systematic characterization of microbes in several tumors including colorectal cancer (CRC) and pancreatic ductal adenocarcinoma (PDAC) has revealed the presence of multiple species of intracellular bacteria within tumors. However, there is limited knowledge on how these bacteria colonize tumors, how they survive inside host cells, how they modulate host cell phenotypes, and if their elimination should complement cancer therapy. This is, in part, due to the lack of representative animal models, challenges in co-culture of host epithelial cells and bacteria, and limited resolution of available analytical techniques to study host-microbial interactions. I have addressed these challenges by harnessing multiple technologies from microbiology, genetic engineering, tissue engineering, and microfluidics, in order to investigate the role of an emerging oncomicrobe, Fusobacterium nucleatum, in the tumor microenvironment (TME). F. nucleatum is a Gram-negative, anaerobic bacterium that is normally found within the oral cavity. However, its selective enrichment in CRC and PDAC tumors is correlated with poor clinical outcomes. My work along with collaborators in the Verbridge, Slade, and Lu labs at Virginia Tech has revealed a multifactorial impact of F. nucleatum in influencing cancer progression. First, in CRC, we discovered that F. nucleatum infection of host cancer cells induced robust secretion of select cytokines that increased cancer cell migration, impacted cell seeding, and enhanced immune cell recruitment. In PDAC, we uncovered additional cytokines that were secreted from both normal and cancerous pancreatic cell lines upon infection with F. nucleatum that increased cancer cell proliferation and migration via paracrine and autocrine signaling, notably in the absence of immune cell participation. In order to examine the contribution of a hypoxic TME on infection dynamics, we used a multi-omics approach that combined RNA-seq and ChIP-seq of H3K27ac to determine epigenomic and transcriptomic alterations sustained within hypoxic CRC cells upon infection with F. nucleatum. Our findings revealed that F. nucleatum can subvert host cell recognition in hypoxia and can modulate the expression of multiple cancer-related genes to drive malignant transformation. Insights gained from this research will pave the way for future studies on the impact of the tumor microbiome in cancer and will identify novel targets for therapy and clinical intervention to control bacteria-induced exacerbation of cancer. / Doctor of Philosophy / Colorectal cancer (CRC) and pancreatic ductal adenocarcinoma (PDAC) are the second and third leading causes of cancer death in the United States, respectively. Recent systematic characterization of various tumor types revealed the presence of distinct bacteria within tumors. However, there is limited knowledge on how these bacteria colonize tumors, how they survive inside host cells, how they modulate host cell phenotypes, and if their elimination should complement cancer therapy. This is, in part, due to the lack of representative animal models, challenges in developing host cell-microbe co-culture models, and limited resolution of available analytical techniques to study host-microbial interactions. I have addressed these challenges by harnessing multiple technologies from microbiology, genetic engineering, tissue engineering, and microfluidics, in order to investigate the role of an emerging cancer-associated microbe, Fusobacterium nucleatum, in the tumor microenvironment (TME). F. nucleatum is a microbe commonly found within the oral cavity. However, clinical studies revealed that selective enrichment of F. nucleatum in CRC and PDAC tumors significantly correlated with poor prognosis. My work along with collaborators in the Verbridge, Slade, and Lu labs at Virginia Tech has revealed a multifactorial impact of F. nucleatum in influencing cancer progression. First, in CRC, we discovered that F. nucleatum invasion of host cancer cells induced the secretion of select proteins called cytokines that cells use to signal and communicate with each other. These cytokines directly stimulated the cell migration of host cancer cells which is usually associated with increased cancer aggressiveness. In PDAC, F. nucleatum infection induced the secretion of additional cytokines from both cancer cells and normal cells that, in addition to cell migration, impacted the proliferation of cancer cells, another feature of aggressive cancers. F. nucleatum usually thrives in a low oxygen environment that is prevalent in cancer tissue and hence, we examined how a low oxygen environment can influence infection dynamics using sequencing technologies that probe the genomic constitution within cells. Our findings revealed that F. nucleatum can escape recognition in low oxygen environments and can modulate the expression of multiple cancer-related programs within the cell to drive cancer progression. Insights gained from this research will pave the way for future studies on the impact of the tumor-associated microbes in cancer and will identify novel targets for therapy and clinical intervention to control bacteria-induced exacerbation of cancer.
163

Upplevelsen av att leva med pankreascancer : En litteraturöversikt / Experiences of living with pancreatic cancer : A literature review

Eliasson, Emma, Karlsson, Piotr Edvard January 2024 (has links)
Pancreatic cancer is a form of severe neoplasm with a swift disease progression and a high rate of mortality. It is the 12th leading cause of death globally for all cancer-related mortalities. Diagnosis is often late in the disease progression due to the late manifestation of symptoms which limits curative treatment options, resulting in primary palliative treatments. Patients experience a broad variety of symptoms that affect their physical and mental health causing a tremendous symptom burden. Therefore, the aim of this study was to describe the patient’s experience of living with pancreatic cancer. A literature review of qualitative and quantitative research articles was conducted to answer the purpose of this study. Data was collected through Cinahl, PsycINFO and PubMed and generated eleven articles which were analyzed, nine qualitative and two quantitative. The results were presented in two categories living in uncertainty which presented the patients emotions associated with getting the diagnosis together with unmeet informational needs and living with an unwell body which presented the physical bodily changes. This study concluded that pancreatic cancer has a significant impact on both the patients’ physical and mental health. Furthermore, there was a correlation between physical and psychological symptoms that all affected the patients' state of well-being. Moreover, patients experienced a lack of sufficient information concerning the disease. Therefore, it is of utmost importance that the patient is seen as a whole entity by the healthcare personnel to meet the individual care needs that arise from the illness.
164

Livskvalitet hos personer med pankreascancer : En allmän litteraturstudie / Quality of life in people with pancreatic cancer : A general literature study

Henricson, Zandra, Berggren, Emelie January 2022 (has links)
Bakgrund: Pankreascancer är den fjärde vanligaste orsaken till cancerrelaterade dödsfall. Sjukdomen påverkar bukspottskörteln i buken som producerar enzymer och hormoner. Sjukdomen upptäcks ofta i ett sent skede, vilket gör att behandlingsalternativen är begränsade. Sjuksköterskans roll vid omvårdnad av personer med pankreascancer är att främja hälsa och upprätthålla god livskvalité. Syfte: Syftet var att beskriva livskvalitet hos personer med pankreascancer. Metod: Studien genomfördes som en allmän litteraturstudie där 11 resultatartiklar framkom. Resultatartiklarna granskades, bearbetades och sammanställdes till tre huvudkategorier med fyra underkategorier. Resultat: De huvudkategorier som framkom var: Fysiska och fysiologiska förändringar, Psykiska och psykologiska förändringar och Sociala förändringar. De fyra underkategorier som framkom var: Trötthetens betydelse för livskvalitén, Fysiska funktionens betydelse för livskvalitén, Nutritionsbesvärens betydelse för livskvalitén och Smärtans betydelse för livskvalitén. Det framkom att personers livskvalitet med pankreascancer påverkades både fysiskt, psykiskt och socialt. Konklusion: Cancerrelaterade symtom hade stor påverkan för hur personer med pankreascancer upplevde livskvalitet. Sjuksköterskan kan med kunskap om sjukdomen ge stöd i livets slutskede och därmed främja livskvalitet och tillgodose grundläggande behov. / Background: Pancreatic cancer is the fourth most common cause of cancer-related deaths. The disease affects the pancreas in the abdomen, which produces enzymes and hormones. The disease is often detected at a late stage, which means that treatment options are limited. The nurse's role in caring for people with pancreatic cancer is to promote health and maintain a good quality of life. Purpose: The purpose was to describe quality of life in people with pancreatic cancer. Method: The study was conducted as a general literature study where 11 result articles emerged. The resulting articles were reviewed, processed and compiled into three main categories with four subcategories. Results: The main categories that emerged were: Physical and physiological changes, Mental and psychological changes and Social changes. The four subcategories that emerged were: Importance of fatigue for quality of life, Importance of physical function for quality of life, Importance of nutritional problems for quality of life and Importance of pain for quality of life. It emerged that the quality of life of people with pancreatic cancer was affected both physically, psychologically and socially. Conclusion: Cancer-related symptoms had a major impact on how people with pancreatic cancer experienced quality of life. With knowledge of the disease, the nurse can provide support at the end of life and thereby promote quality of life and meet basic needs.
165

Therapeutic miR-506-3p Replacement in Pancreatic Carcinoma Leads to Multiple Effects including Autophagy, Apoptosis, Senescence, and Mitochondrial Alterations In Vitro and In Vivo

Borchardt, Hannes, Kogel, Alexander, Kalwa, Hermann, Weirauch, Ulrike, Aigner, Achim 03 November 2023 (has links)
Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer mortality. Considering its very poor prognosis, novel treatment options are urgently needed. MicroRNAs (miRNAs) are involved in the regulation of various physiological and pathological processes. In tumors, aberrant downregulation of given miRNAs may result in pathological overexpression of oncogenes, rendering miRNA replacement as a promising therapeutic strategy. In different tumor entities, miRNA-506-3p (miR506-3p) has been ambivalently described as tumor suppressing or oncogenic. In PDAC, miR-506 is mainly considered as a tumor-suppressing miRNA. In this study, we extensively analyze the cellular and molecular effects of miRNA-506-3p replacement in different PDAC cell lines. Beyond profound antiproliferation and induction of cell death and autophagy, we describe new cellular miR506-3p effects, i.e., induction of senescence and reactive oxygen species (ROS), as well as alterations in mitochondrial potential and structure, and identify multiple underlying molecular effects. In a preclinical therapy study, PDAC xenograft-bearing mice were treated with nanoparticle-formulated miRNA-506 mimics. Profound tumor inhibition upon systemic miRNA-506 administration was associated with multiple cellular and molecular effects. This demonstrates miRNA replacement as a potential therapeutic option for PDAC patients. Due to its broad mechanisms of action on multiple relevant target genes, miR506-3p is identified as a particularly powerful tumor-inhibitory miRNA.
166

Combined Systemic Drug Treatment with Proton Therapy: Investigations on Patient-Derived Organoids

Naumann, Max, Czempiel, Tabea, Lößner, Anna Jana, Pape, Kristin, Beyreuther, Elke, Löck, Steffen, Drukewitz, Stephan, Hennig, Alexander, von Neubeck, Cläre, Klink, Barbara, Krause, Mechthild, William, Doreen, Stange, Daniel E., Bütof, Rebecca, Dietrich, Antje 20 February 2024 (has links)
To optimize neoadjuvant radiochemotherapy of pancreatic ductal adenocarcinoma (PDAC), the value of new irradiation modalities such as proton therapy needs to be investigated in relevant preclinical models. We studied individual treatment responses to RCT using patient-derived PDAC organoids (PDO). Four PDO lines were treated with gemcitabine, 5-fluorouracile (5FU), photon and proton irradiation and combined RCT. Therapy response was subsequently measured via viability assays. In addition, treatment-naive PDOs were characterized via whole exome sequencing and tumorigenicity was investigated in NMRI Foxn1nu/nu mice. We found a mutational pattern containing common mutations associated with PDAC within the PDOs. Although we could unravel potential complications of the viability assay for PDOs in radiobiology, distinct synergistic effects of gemcitabine and 5FU with proton irradiation were observed in two PDO lines that may lead to further mechanistical studies. We could demonstrate that PDOs are a powerful tool for translational proton radiation research.
167

Testing Mice at Risk of Pancreatic Cancer for Altered Protein Pathways Found in Diabetes

Cheung, Henley 01 January 2017 (has links)
Pancreatic cancer is nearly asymptomatic, which can result in extensive grow and even metastasis to other organs before detection. When diagnosed at a late stage, the survival rate is 3%. Early detection is therefore the key to treating pancreatic cancer. Diabetes was identified as a risk factor for the development of pancreatic cancer, but the mechanism remains unknown. In this project, the objective was to delineate a link between diabetes and pancreatic cancer by examining their shared protein signaling pathways. In a previous study, hyper-activation of AKT1 resulted in a pre-diabetic phenotype and also increased upregulation of downstream phosphorylated mTOR and phosphorylated p70S6 kinase. More recently, mice with mutations that hyper-activated AKT1 and KRAS showed a significantly higher blood glucose level compared to littermate matched wild-type, mutant AKT1, or mutant KRAS mice. Interestingly, mice with a combination of mutations that hyper-activated AKT1 and KRAS also showed faster development of pancreatic cancer compared to these other groups of littermate mice. Toward determining a molecular basis for the crosstalk between AKT1 and KRAS, pancreas and liver tissues were collected from all four groups of mice including wild-type, mutant AKT1, mutant KRAS, and mice with dual AKT1/KRAS hyper-activation. One strategy was to examine expression and/or phosphorylation of downstream protein signaling crosstalk by analysis of p70S6K using Western Blots. Erk 1/2 proteins were also tested as downstream proteins of KRAS to provide a molecular view of the individual and cooperative roles of AKT1 and KRAS in the mouse models. A potential feedback mechanism to affect insulin receptor signaling in the pancreas was examined using enzyme-linked immunosorbent assays (ELISA). A significant decrease in insulin receptor phosphorylation, possibly contributing to insulin resistance, was found when mice had mutant hyper-activated KRAS. Contrary to the original expectations, mice with combined mutations of AKT1 and KRAS may contribute to the accentuated diabetic phenotype by targeting two different points in the AKT and KRAS protein signaling pathways. The information can help understand the relationship between glucose metabolism, diabetes, and pancreatic cancer development. By thoroughly studying the interactions between targets in the AKT1/KRAS signaling pathways, key molecular events that induce metabolic changes and potentially early biomarkers may lead to an improved understanding of risk and/or detection of pancreatic cancer.
168

Role of Interleukin-21 and the Interleukin-21 Receptor in Natural Killer Cell Activation

McMichael, Elizabeth L. 06 September 2016 (has links)
No description available.
169

Chemosensitization of pancreatic tumors with the use of low-dose suramin

Ogden, Adam Gregory 19 May 2004 (has links)
No description available.
170

Suramin as a chemo- and radio-sensitizer: preclinical translational studies

Xin, Yan 14 July 2006 (has links)
No description available.

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