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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.
61

The impact of hypoxia on tumour control probability in the high-dose range used in stereotactic body radiation therapy

Lindblom, Emely January 2012 (has links)
The use of stereotactic body radiation therapy employing few large fractions of radiation dose for the treatment of non-small cell lung cancer has been proven very successful, high values of tumour control probability (TCP) being clinically achieved. In spite of the success of the fractionation schedules currently used, there is a tendency towards reducing the number of fractions for economical and practical reasons, and also for maximizing the comfort of the patients. It is therefore the main aim of this thesis to investigate the impact of a severely reduced number of fractions on the tumour control probability for tumours that contain hypoxic areas. The impact on TCP of other factors such as hypoxic fraction, distribution of the oxygen partial pressure and location of the hypoxic volume within the tumour were also investigated. The effect of tumour motion due to breathing was included and evaluated using Cone Beam Computed Tomography (CBCT) data from patients imaged with internal markers in the liver and pancreas. The results clearly showed that in the presence of hypoxia, TCP is seriously compromised if there is not enough time for reoxygenation between fractions. A reduction in the number of fractions of just one fraction may require an increase of several Gy per fraction to obtain a similar TCP. The diaphragmatic tumour motion range showed little influence on TCP provided that the PTV encompassed all tumour positions. The dose delivered to the PTV margin was found not to be the only factor that is significant for local control, the average dose correlated better with TCP. The agreement of the results of this work with clinical results also serve as a strong indicator that inter-fraction reoxygenation is an important process in real-life patients treated with stereotactic body radiotherapy.
62

Nitric oxide synthases and reactive oxygen species damage in pleural and lung tissues and neoplasia

Puhakka, A. (Airi) 19 April 2005 (has links)
Abstract Reactive nitrogen species (RNS) and reactive oxygen species (ROS) have been linked with the pathogenesis of lung malignancies and chronic obstructive pulmonary disease (COPD). In vitro studies indicated that mesothelioma and lung carcinoma cell lines synthesize nitric oxide synthases (NOS) mRNA. The Comet-assay indicated that asbestos fibers caused DNA single -strand breaks in mesothelial cells, and this effect was enhanced by glutathione depletion. The use of FPG in the Comet assay indicated that the asbestos induced DNA strand breaks were oxidant mediated. In vivo non-neoplastic pleura was mostly negative for inducible NOS (iNOS), while inflamed pleura was positive. The immunohistochemical expression of iNOS was detected in 74% and 96% of malignant mesotheliomas and metastatic pleural adenocarcinomas, respectively. Epithelial and mixed mesotheliomas expressed more often intense iNOS immunoreactivity compared to the sarcomatoid subtype. Normal mesothelial cells showed occasional positivity for endothelial NOS (eNOS), but reactive mesothelial cells were strongly stained. eNOS was found in 89% of mesotheliomas. Vascular endothelial growth factor (VEGF) was identified in 47%, a VEGF receptor FLK1 in 69% and the VEGF receptor, FLT1, in 71% of mesotheliomas. FLK1 or FLT1 immunoreactivities were more often seen in epithelioid and biphasic mesotheliomas than in sarcomatoid mesotheliomas. In lung samples of non-smokers, smokers and COPD patients, the levels of nitrotyrosine were higher in alveolar macrophages of smokers and COPD patients than in the non-smokers and in the alveolar epithelium of smokers and COPD patients than in the non-smokers. The iNOS expression was weak in the bronchial and alveolar epithelium in all groups but eNOS was most prominently expressed in alveolar macrophages while neuronal NOS (nNOS) was negative in all of the major cell types of the lung. Bronchial metaplasia-dysplasia-sequence was clearly positive for iNOS, nNOS and nitrotyrosine. Thus, smoking can cause protein nitration also in normal lung. Prominent iNOS and nNOS immunoreactivity in metaplasia-dysplasia-lesions suggests a divergent role of NOSs in carcinogenesis and destruction of alveolar epithelium in emphysematous lung. In lung cancer samples, iNOS was detected in 40% cases, while 89% and 81% cases were positive for eNOS and nNOS, respectively. Intense eNOS staining was seen more often in adenocarcinomas than in squamous cells carcinomas, and iNOS immunoreactivity was seen more often in grade I-II tumors than in grade III tumors. The patients with tumors showing high expression of iNOS, eNOS and nNOS, exhibited better survival, but this was not an independent prognostic factor.
63

An Algorithm to Improve Deformable Image Registration Accuracy in Challenging Cases of Locally-Advanced Non-Small Cell Lung Cancer

Guy, Christopher L 01 January 2017 (has links)
A common co-pathology of large lung tumors located near the central airways is collapse of portions of lung due to blockage of airflow by the tumor. Not only does the lung volume decrease as collapse occurs, but fluid from capillaries also fills the space no longer occupied by air, greatly altering tissue appearance. During radiotherapy, typically administered to the patient over multiple weeks, the tumor can dramatically shrink in response to the treatment, restoring airflow to the lung sections which were collapsed when therapy began. While return of normal lung function is a positive development, the change in anatomy presents problems for future radiation sessions since the treatment was planned on lung geometry which is no longer accurate. The treatment must be adapted to the new lung state so that the radiation continues to accurately target the tumor while safely avoiding healthy tissue. However, to account for the dose delivered previously, correspondences of anatomy between the former image when the lung was collapsed and the re-expanded lung in a current image must be obtained. This process, known as deformable image registration, is performed by registration software. Most registration algorithms assume that identical anatomy is contained in the images and that intensities of corresponding image elements are similar; both assumptions are untrue when collapsed lung re-expands. This work was to develop an algorithm which accurately registers images in the presence of lung expansion. The lung registration method matched CT images of patients aided by vessel enhancement and information of individual lobe boundaries. The algorithm was tested on eighteen patients with lung collapse using physician-specified correspondences to measure registration error. The image registration algorithm developed in this work which was designed for challenging lung patients resulted in accuracy comparable to that of other methods when large lung changes are absent.
64

Neuroendocrine and epithelial markers of small cell lung cancer

Bryant, Jennifer January 2015 (has links)
Small cell lung cancer (SCLC) is an extremely aggressive disease characterized by early metastasis and acquired resistance to therapy. SCLC is distinguished by its neuroendocrine (NE) component; the role of which is not fully understood in metastasis and response to therapy. Patients respond exceptionally well to first round chemotherapy; however, relapse with therapy-resistant tumours is virtually inevitable. Hypoxic regions within tumours can contribute towards metastasis and therapy resistance, highlighting hypoxia-targeted therapy as a novel approach for improving treatment for SCLC patients. Tumours are highly phenotypically heterogeneous, raising debate over the roles played by each cell type. Analysis of NE and epithelial markers in SCLC cell lines highlighted this inter-tumour heterogeneity. Further heterogeneity is displayed in SCLC xenograft tumours that show areas of dual epithelial and NE marker expression as well as regions negative for both markers. Irradiating xenograft tumours enhanced heterogeneity of the NE marker, pro-opiomelanocortin (POMC), which is ectopically secreted by a subset of SCLC tumours. Examining changes in marker expression post-therapy could provide vital information regarding transitions that can serve to guide therapy. SCLC is a highly metastatic disease. The role of the NE phenotype in human SCLC is not fully understood, but is considered essential for metastasis in murine models. Sub-cutaneous, intravenous and intra-splenic injection were carried out and resulted in no metastasis, spontaneous tumour generation and peripheral liver tumour growth, respectively. POMC expression was present and extremely heterogeneous within the liver, suggesting that NE properties are maintained in metastases; however, further work is necessary to develop a more consistent metastatic model that can be used to assess responses to therapy in a more clinically relevant setting. SCLC tumours proliferate rapidly and outgrow their nutrient and oxygen supplies, resulting in hypoxic conditions. Here, carbonic anhydrase IX (CA IX) becomes up-regulated in order to maintain pH levels suitable for survival. The specific CA IX inhibitor, S4, induces hypoxia-specific cell death in vitro and impairs tumour growth in vivo. This response is further accentuated by combining S4 with single or repeated cisplatin doses. Combination treatment reduced gene expression of S-phase kinase-associated protein (Skp2), associated with cisplatin resistance. CA IX inhibition combined with cisplatin chemotherapy therefore presents a novel treatment for SCLC tumours that could reduce therapy resistance. In summary, heterogeneity is extremely important when choosing treatment options for SCLC and must be considered when basing treatment on single biopsies. NE and epithelial markers are present within sub-cutaneous and liver tumours; however, a reliable multi-organ metastatic model is necessary to fully appreciate the role of these markers in the spread of SCLC. Hypoxic regions within sub-cutaneous xenograft tumours upregulate CA IX. Inhibition of this enzyme resulted in impaired tumour growth, particularly when used together with cisplatin. Combining CA IX inhibition with cisplatin presents a much-needed novel therapy for SCLC.
65

Contribución al modelado y al análisis mediante Teoría de Juegos de la competencia entre operadores móviles en escenarios con tecnología "small cell"

Romero Chavarro, Julián Camilo 25 July 2017 (has links)
The present doctoral thesis has been realized in accordance with the research line of Economy and Regulation in Telecommunications under the doctoral programme in Telecommunications of Universitat Politècnica de València. It has been developed on the basis of various research projects, especially the "Cooperation and Opportunity for Wireless Heterogeneous Networks Project" (TIN2010-21378-C02-02), which acted as my funding agent and the "S2EuNet-Security Project" . Mobile communications have undergone notable growth from their beginning up to the present day regarding devices and bandwidth available. Service providers have now to take the challenge of such increase. New technologies are being implemented to address the challenge and all of them belong to the world of mobile communications. This thesis will focus on the solutions provided by heterogeneous nets (HetNets) and, more speci¿cally, we will look at the Small Cells technology. It is starting to be widely deployed lately and allows for a visible increase in network capacity and a resulting enhancement in availability and coverage on the user side. Abundant research has proved that the integration of these technologies within markets is technically feasible. A marketing model is however still necessary which is able to prove its economic viability. A business model was laid out where a provider sets out to deploy small cells technology and stands as an incumbent service provider. The Theory of Games was used for the analysis of such models as it allows an insight of the decisions in equilibrium when entering into a competition among themselves and try the decisions of users need to be predicted. In this way we will manage to know the effect of such decisions over the pro¿ts of all the agents in the model. A clear picture will be thus obtained of the advantages of the implementation of the new technology in the market as well as of its effects over the incumbent service providers. This thesis intends to be a contribution towards the implementation of new technologies in the market of mobile technologies through the analysis of the competence between new service providers of Small Cells and an incumbent service providers along with the behaviour of the users of mobile communications. The result show that: users get a better service, the SSP pro¿ts are guaranteed and the entrance of the SSP improves the user comfort and social welfare. / Esta tesis se ha creado en el marco de la línea de investigación de Economía y Regulación de las Telecomunicaciones del programa de doctorado de Telecomunicaciones de la Universitat Politècnica de València, y se ha desarrollado en diferentes proyectos de investigación, en especial, el proyecto de "Cooperación yOportunismo enRedesde Acceso Inalámbricas y Heterogéneas" (TIN2010-21378-C02-02) y el proyecto S2EuNet-Security (FP7PEOPLE-2009- IRSES, 247083). Desde sus inicios las comunicaciones móviles han experimentado un gran crecimiento, tanto de dispositivos móviles como de cantidad de ancho de banda demandado, lo que ha provocado que los proveedores se encuentren con el desafío de hacer frente a este crecimiento. Para ello, se están implementando diferentes técnicas y tecnologías que se integran con el modeloactualdecomunicacionesmóviles.Enestatesisnoscentraremosenla solución que aportan las redes heterogéneas, especialmente en la tecnología de Small cells que se desplegado rápidamente en los últimos años y permite incrementar la capacidad de la red, así como obtener mejor disponibilidad y cobertura para los usuarios, pero falta un modelo de negocio claro donde se muestre su viabilidad económica. En esta tesis se plantea un modelo de negocio para un proveedor de servicio que despliega small cells y que compite como el proveedor de servicios incumbente. Para el análisis de este modelo se ha utilizado la Teoría de Juegos la cual ha permitido conocer las decisiones en equilibrio que toman los proveedores de servicio cuando compiten entre sí, así como las decisiones en equilibrio de los usuarios; de esta manera se ha obtenido el efecto de estas decisiones sobre los bene¿cios de todos los agentes del modelo y se han identi¿cado las ventajas y los inconvenientes que tiene la implementación de una nueva tecnología en el mercado. Esta tesis pretende ser una contribución al estudio de implementación de nuevas tecnologías en el mercado de comunicaciones móviles, más concretamente planteando modelos económicos que estudien su viabilidad a través del análisis de la competencia entre un nuevo proveedor se servicio de Small cells y el proveedor de servicio existente, y el comportamiento de los usuarios de comunicaciones móviles. Los resultados obtenidos muestran que los usuarios obtienen una mejor utilidad , el SSP siempre tiene unos bene¿cios garantizados, el MSP se ve obligado a competir y sus bene¿cios se ven perjudicados, además que la entrada del SSP mejora el bienestar de los usuarios y el bienestar social. / Aquesta tesi s'ha creat en el marc de la línia de recerca d'Economia i Regulació de les Telecomunicacions del programa de doctorat de Telecomunicacions de la Universitat Politècnica de València, i s'ha desenvolupat en diferents projectes de recerca, especialment, el projecte de Çooperació i Oportunisme en Xarxes d'Accés Sense ¿ls i Heterogènies"(TIN2010-21378-C02-02) i el projecte S2EuNet-Security (FP7PEOPLE-2009- IRSES, 247083). Des dels seus inicis les comunicacions mòbils han experimentat un gran creixement, tant de dispositius mòbils com de quantitat d'amplada de banda demandada, la qual cosa ha provocat que els proveïdors es troben amb el desa¿amentdeferfrontaaquestcreixement.Peraaixò,s'estanimplementant diferents tècniques i tecnologies que s'integren amb el model actual de comunicacions mòbils. En aquesta tesi ens centrarem en la solució que aporten les xarxes heterogènies, especialment a la tecnologia de Small cells que s'ha desplegat ràpidament en els últims anys i permet incrementar la capacitat de la xarxa, així com obtenir millor disponibilitat i cobertura per als usuaris, però falta un model de negoci clar on es mostre la seua viabilitat econòmica. En aquesta tesi es planteja un model de negoci per a un proveïdor de servei que desplega Small cells i que competeix com el proveïdor de serveis incumbent. Per a l'anàlisi d'aquest model s'ha utilitzat la Teoria de Jocs la qual ha permès conéixer les decisions en equilibri que prenen els proveïdors de servei quan competeixen entre si, així com les decisions en equilibri dels usuaris; d'aquesta manera s'ha obtingut l'efecte d'aquestes decisions sobre els bene¿cis de tots els agents del model i s'han identi¿cat els avantatges i els inconvenients que té la implementació d'una nova tecnologia al mercat. Aquesta tesi pretén ser una contribució a l'estudi d'implementació de noves tecnologies al mercat de comunicacions mòbils, més concretament plantejant models econòmics que estudien la seua viabilitat a través de l'anàlisi de la competència entre un nou proveïdor se servei de Small cells i el proveïdor de servei existent, i el comportament dels usuaris de comunicacions mòbils. Els resultats obtinguts mostren que els usuaris obtenen una millor utilitat, el SSP sempre té uns bene¿cis garantits, el MSP es veu obligat a competir i els seus bene¿cis es veuen perjudicats, a més que l'entrada del SSP millora el benestar dels usuaris i el benestar social. / Romero Chavarro, JC. (2017). Contribución al modelado y al análisis mediante Teoría de Juegos de la competencia entre operadores móviles en escenarios con tecnología "small cell" [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/85681 / TESIS
66

Statins may have double-edged effects in patients with lung adenocarcinoma after lung resection / スタチンは肺切除術後の肺腺がん患者において有益にも有害にもなりうる

Nishikawa, Shigeto 23 July 2019 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22005号 / 医博第4519号 / 新制||医||1038(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 平井 豊博, 教授 松原 和夫, 教授 萩原 正敏 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
67

Efficacy and safety analysis according to histology for S-1 in combination with carboplatin as first-line chemotherapy in patients with advanced non-small-cell lung cancer: updated results of the West Japan Oncology Group LETS study / 未治療進行非小細胞肺癌患者に対するS-1とカルボプラチンの併用療法の有効性と安全性の組織型別解析:西日本がん研究機構LETS試験の最新結果

Yoshioka, Hiroshige 23 January 2014 (has links)
京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第12803号 / 論医博第2075号 / 新制||医||1001(附属図書館) / 80847 / (主査)教授 伊達 洋至, 教授 武藤 学, 教授 川上 浩司 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM
68

Radiation sensitivity assay with a panel of patient-derived spheroids of small cell carcinoma of the cervix / 子宮頸部小細胞癌の患者由来スフェロイドパネルを用いた放射線感受性試験

Nakajima, Aya 23 March 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18869号 / 医博第3980号 / 新制||医||1008(附属図書館) / 31820 / 京都大学大学院医学研究科医学専攻 / (主査)教授 武田 俊一, 教授 小西 郁生, 教授 小松 賢志 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
69

Mechanisms of acquired resistance to EGFR tyrosine kinase inhibitors in EGFR-mutant non-small cell lung cancer

Gergis, Carol 07 October 2019 (has links)
Non-small cell lung cancer (NSCLC) makes up the majority of lung cancers, which remains the leading cause of cancer mortality worldwide. NSCLC with mutant epidermal growth factor receptor (EGFR) is currently treated with tyrosine kinase inhibitors (TKIs). TKIs have proven effective in improving survival until resistance is conferred, mostly by way of the exon 20, threonine 790 to methionine (T790M) point mutation in EGFR. The mechanism by which this point mutation arises is poorly understood. Herein we report a possible pathway by which the C to T transition that leads to T790M comes about. We show that activation-induced cytidine deaminase (AID) mRNA expression is induced upon treatment with EGFR TKIs in mutant-EGFR human lung cancer cell lines but not in control cell lines. We also show that stable expression of AID is sufficient to produce resistance to one such TKI, erlotinib, and is sufficient to produce T790M itself. We also report that B-cell lymphoma 6 (BCL6) may precede AID in this pathway. Our results show that BCL6 is upregulated in these cell lines treated with EGFR TKIs but not in normal bronchial cells. We then treated human lung cancer cell lines with EGFR TKIs in combination with BCL6 inhibitors. Our results show that AID is dependent upon BCL6 expression. Finally, we report on results from a transient BCL6 overexpression which lead us to believe that AID mRNA receives input from at least one alternate pathway in addition to BCL6. We also performed these experiments on a family of apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) cytidine deaminases, that show they may be involved in this pathway downstream of AID. Taken together, our results suggest a potential pathway involving BCL6, AID, and APOBEC cytidine deaminases that lead to the C to T transition that produces T790M, thereby conferring resistance to EGFR TKIs in mutant-EGFR NSCLC. They also provide potential new targets for treatment should further study confirm our results. / 2021-10-07T00:00:00Z
70

Small Cell Medullary Thyroid Cancer: A Therapeutic Dilemma

Sherret, John, Coleman, Joshua 13 May 2020 (has links)
Small cell variant of medullary thyroid carcinoma is an extremely rare histologic entity with a paucity of data. As such, there is a lack of clinical experience regarding this disease. In this case, a 52-year-old patient with small cell variant medullary thyroid carcinoma was experiencing intractable nausea, vomiting, and diarrhea. The initial workup was extensive yet unrevealing. He was refractory to all treatments. On further laboratory analysis, the calcitonin was substantially high and the thyroid stimulating hormone level was mildly elevated. This case is presented to highlight a possible treatment for this rare cancer through thyroxine suppression therapy. This case is presented due to the lack of literature available on small cell medullary thyroid carcinoma and also to discuss a possible direct relationship between thyroid stimulating hormone and calcitonin levels in this disease population.

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