• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 275
  • 145
  • 59
  • 48
  • 23
  • 12
  • 11
  • 10
  • 7
  • 6
  • 5
  • 4
  • 2
  • 2
  • 2
  • Tagged with
  • 733
  • 186
  • 137
  • 90
  • 87
  • 87
  • 82
  • 79
  • 75
  • 71
  • 68
  • 57
  • 52
  • 49
  • 49
  • 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.
351

On CD4<sup>+</sup> T Lymphocytes in Solid Tumours

Marits, Per January 2007 (has links)
<p>This thesis deals with recognition and elimination of tumours by T lymphocytes and their use in adoptive immunotherapy.</p><p>The first tumour-draining lymph node; the sentinel node, is identified by peritumoural injection of a tracer. This is the hypothesised location for the activation of tumour-reactive lymphocytes. Accordingly, proliferation and IFN-γ production in response to autologous tumour extract was detected in sentinel nodes from patients with colon and urinary bladder cancer. Reactivity in metastatic nodes was generally lower or absent, but the non-responsiveness could be subdued in long-term cultures by addition of tumour antigen and IL-2. A novel padlock-probe based method was developed for measuring the T cell receptor Vβ repertoire. Common Vβ gene expansions were detected in tumour-infiltrating lymphocytes and sentinel nodes. Thus, tumour antigens are recognised in sentinel nodes by Th1 lymphocytes, resulting in a clonally expanded cell population that can be further propagated <i>ex vivo</i>.</p><p>Regulatory T cells (Tregs) may contribute to tumour-induced immunosuppression. Immunohistochemical stainings against the pan-T cell marker CD3 and Treg marker FOXP3 was performed on tumour tissue from 20 historical urinary bladder cancer patients. The ratio of FOXP3<sup>+</sup> to CD3<sup>+</sup> cells was lower in patients alive 7 years post-cystectomy, suggesting that Tregs in bladder cancer have prognostic implications.</p><p>Lymphocytes were isolated from sentinel nodes from sixteen patients with advanced or high-risk colon cancer. <i>In vitro</i> expansion with addition of autologous tumour extract and IL-2 mainly promoted the outgrowth of CD4<sup>+</sup> Th1 lymphocytes, which were safely re-transfused to the patients. Four patients responded with complete tumour regression. Survival time in the Dukes’ D patients was significantly increased compared with conventionally treated controls (2.6 versus 0.8 years; p=0.048).</p><p>In conclusion, human solid tumours are recognised in sentinel nodes and <i>in vitro</i> expanded sentinel node-acquired CD4<sup>+</sup> T lymphocytes seem useful in the treatment of patients with disseminated cancer.</p>
352

Collaborative beamforming for wireless sensor networks

Ahmed, Mohammed 11 1900 (has links)
Collaborative Beamforming (CB) has been introduced in Wireless Sensor Networks (WSNs) context as a long-distance and power-efficient communication scheme. One challenge for CB is the randomness of sensor node locations where different network realizations result in different CB beampatterns. First, we study the effect of sensor node spatial distribution on the CB beampattern. The characteristics of the CB beampattern are derived for circular Gaussian distributed sensor nodes and compared with the case of uniform distributed sensor nodes. It is shown that the mainlobe behavior of the CB beampattern is essentially deterministic. This suggests that the average beampattern characteristics are suitable for describing the mainlobe of a sample beampattern. However, the CB beampattern sidelobes are random and highly depends on the particular sensor node locations. Second, we introduce the multi-link CB and address the problem of random sidelobes where high level sidelobes can cause unacceptable interference to unintended Base Stations or Access Points (BSs/APs). Centralized sidelobe control techniques are impractical for distributed sensor nodes because of the associated communication overhead for each sensor node. Therefore, we propose a node selection scheme as an alternative to the centralized sidelobe control which aims at minimizing the interference at unintended BSs/APs. Our algorithm is based on the use of the inherent randomness of the channels and a low feedback that approves/rejects tested random node combinations. The performance of the proposed algorithm is analyzed in terms of the average number of trials and the achievable interference suppression and transmission rate. Finally, we study CB with power control aiming at prolonging the lifetime of a cluster of sensor nodes in the WSN. The energy available at different sensor nodes may not be the same since different sensor nodes may perform different tasks and not equally frequently. CB with power control can be used to balance the individual sensor nodes' lifetimes. Thus, we propose a distributed algorithm for CB with power control that is based on the Residual Energy Information (REI) at each sensor node while achieving the required average SNR at the BS/AP. The effectiveness of the proposed CB with power control is illustrated by simulations. / Communications
353

Studies on Prediction of Axillary Lymph Node Status in Invasive Breast Cancer

Ahlgren, Johan January 2002 (has links)
Breast cancer is the most common malignancy among females in Sweden. Axillary lymph-node dissection is a standard procedure in the management of breast cancer, aiming at obtaining prognostic information for adjuvant therapy decisions. Axillary dissection entails considerable morbidity. The aims of this study were to establish more selective surgical approaches and to investigate angiogenesis, a potential predictor for lymph-node metastases and prognosis. Clinical nodal status, tumour size and S-phase were associated with nodal metastases in cohort of 1145 women. The proportion of nodal metastases was 13% in the subgroup with the lowest risk. In a study from two registries, 675 and 1035 breast cancers ≤10 mm diagnosed by screening mammography had nodal metastases in 6,5% and 7%, respectively. Clinically detected cancers had a risk of 16% and 14%, respectively. In a study on 415 women, a 5-node biopsy of the axilla had a sensitivity of 97,3% and a false negative rate of 2,7% in comparison with axillary dissection. Six sections from 21 breast cancers were analysed for microvessel density (MVD). The inter-section variation contributed more to the total variance than inter-tumour variation, 45,0% and 37,3%, respectively. In a cohort of 315 women, breast cancers with high MVD more frequently had p53 mutations (27,1%) compared with cases with low MVD (18,4%). This difference was not statistically significant (p=0,075). p53 mutations were associated with a worse outcome, whereas MVD was not. In conclusion, women with screening detected ≤10 mm breast cancers have a low risk of lymph node metastases and some may not need axillary dissection in the future. The 5-node biopsy could be an alternative to axillary dissection. MVD is associated with methodological weaknesses and routine use is not recommended.
354

Development of a Whole Body Atlas for Radiation Therapy Planning and Treatment Optimization

Qatarneh, Sharif January 2006 (has links)
The main objective of radiation therapy is to obtain the highest possible probability of tumor cure while minimizing adverse reactions in healthy tissues. A crucial step in the treatment process is to determine the location and extent of the primary tumor and its loco regional lymphatic spread in relation to adjacent radiosensitive anatomical structures and organs at risk. These volumes must also be accurately delineated with respect to external anatomic reference points, preferably on surrounding bony structures. At the same time, it is essential to have the best possible physical and radiobiological knowledge about the radiation responsiveness of the target tissues and organs at risk in order to achieve a more accurate optimization of the treatment outcome. A computerized whole body Atlas has therefore been developed to serve as a dynamic database, with systematically integrated knowledge, comprising all necessary physical and radiobiological information about common target volumes and normal tissues. The Atlas also contains a database of segmented organs and a lymph node topography, which was based on the Visible Human dataset, to form standard reference geometry of organ systems. The reference knowledgebase and the standard organ dataset can be utilized for Atlas-based image processing and analysis in radiation therapy planning and for biological optimization of the treatment outcome. Atlas-based segmentation procedures were utilized to transform the reference organ dataset of the Atlas into the geometry of individual patients. The anatomic organs and target volumes of the database can be converted by elastic transformation into those of the individual patient for final treatment planning. Furthermore, a database of reference treatment plans was started by implementing state-of-the-art biologically based radiation therapy planning techniques such as conformal, intensity modulated, and radiobiologically optimized treatment planning. The computerized Atlas can be viewed as a central framework that contains different forms of optimal treatment plans linked to all the essential information needed in treatment planning, which can be adapted to a given patient, in order to speed up treatment plan convergence. The Atlas also offers a platform to synthesize the results of imaging studies through its advanced geometric transformation and segmentation procedures. The whole body Atlas is anticipated to become a physical and biological knowledgebase that can facilitate, speed up and increase the accuracy in radiation therapy planning and treatment optimization.
355

On CD4+ T Lymphocytes in Solid Tumours

Marits, Per January 2007 (has links)
This thesis deals with recognition and elimination of tumours by T lymphocytes and their use in adoptive immunotherapy. The first tumour-draining lymph node; the sentinel node, is identified by peritumoural injection of a tracer. This is the hypothesised location for the activation of tumour-reactive lymphocytes. Accordingly, proliferation and IFN-γ production in response to autologous tumour extract was detected in sentinel nodes from patients with colon and urinary bladder cancer. Reactivity in metastatic nodes was generally lower or absent, but the non-responsiveness could be subdued in long-term cultures by addition of tumour antigen and IL-2. A novel padlock-probe based method was developed for measuring the T cell receptor Vβ repertoire. Common Vβ gene expansions were detected in tumour-infiltrating lymphocytes and sentinel nodes. Thus, tumour antigens are recognised in sentinel nodes by Th1 lymphocytes, resulting in a clonally expanded cell population that can be further propagated ex vivo. Regulatory T cells (Tregs) may contribute to tumour-induced immunosuppression. Immunohistochemical stainings against the pan-T cell marker CD3 and Treg marker FOXP3 was performed on tumour tissue from 20 historical urinary bladder cancer patients. The ratio of FOXP3+ to CD3+ cells was lower in patients alive 7 years post-cystectomy, suggesting that Tregs in bladder cancer have prognostic implications. Lymphocytes were isolated from sentinel nodes from sixteen patients with advanced or high-risk colon cancer. In vitro expansion with addition of autologous tumour extract and IL-2 mainly promoted the outgrowth of CD4+ Th1 lymphocytes, which were safely re-transfused to the patients. Four patients responded with complete tumour regression. Survival time in the Dukes’ D patients was significantly increased compared with conventionally treated controls (2.6 versus 0.8 years; p=0.048). In conclusion, human solid tumours are recognised in sentinel nodes and in vitro expanded sentinel node-acquired CD4+ T lymphocytes seem useful in the treatment of patients with disseminated cancer.
356

Evaluating Surgical Outcomes: A Systematic Comparison of Evidence from Randomized Trials and Observational Studies in Laparoscopic Colorectal Cancer Surgery

Martel, Guillaume 10 January 2012 (has links)
Background: Laparoscopic surgery for colorectal cancer is a novel healthcare technology, for which much research evidence has been published. The objectives of this work were to compare the oncologic outcomes of this technology across different study types, and to define patterns of adoption on the basis of the literature. Methods: A comprehensive systematic review of the literature was conducted using 1) existing systematic reviews, 2) randomized controlled trials (RCTs), and 3) observational studies. Outcomes of interest were overall survival, and total lymph node harvest. Outcomes were compared for congruence. Adoption was evaluated by means of summary expert opinions in the literature. Results: 1) Existing systematic reviews were of low to moderate quality and displayed evidence of overlap and duplication. 2) Laparoscopy was not inferior to open surgery in terms of oncologic outcomes in any study type. 3) Oncologic outcomes from RCTs and observational studies were congruent. 4) Expert opinion in the literature has been supportive of this technology, paralleling the publication of large RCTs. Conclusions: The evaluation of laparoscopic surgery for colorectal cancer in RCTs and observational studies suggests that it is not inferior to open surgery. Adoption of this technology has paralleled RCT evidence.
357

Controlled Trans-lymphatic Delivery of Chemotherapy for the Treatment of Lymphatic Metastasis in Lung Cancer

Liu, Jiang 28 July 2008 (has links)
Lymph node metastasis is a critical prognostic factor for lung cancer. Effective therapy to control lymphatic metastasis may improve survival. The work described in this thesis focuses on the development of a microparticulate lymphatic targeting system, which can be applied as an adjuvant therapy in the control of lymphatic metastasis in lung cancer. The study shows that intrapleural administered colloidal particulates are predominantly taken up by regional lymphatic tissue in rat models including healthy rats, rats bearing orthotopic lung tumours and rats following pneumonectomy. The effect of particle size on lymphatic particle distribution was examined by intrapleural administration of 111In-aminopolystyrene beads. Approximately 2 µm is a suitable size for intrapleural lymphatic targeting. Biodegradable polylactide-co-glycolide (PLGA) microparticles containing the anticancer agent paclitaxel (PTX) were subsequently formulated in the desired size by spray drying. PLGA-PTX microspheres were incorporated into a biodegradable and biocompatible gelatin sponge matrix to form an implantable lymphatic targeted drug delivery system. The system was characterized in vitro and its lymphatic targeting ability was examined in vivo. Fluorescence labeled microspheres embedded within the sponge were selectively taken up by regional lymphatics as the sponge matrix disintegrated following intrapleural implantation. A pharmacokinetic study showed that the total PTX exposure in lymphatic tissue was dramatically higher than that achieved through intravenous administration. The peak plasma drug concentration, which governs systemic toxicity, was significantly reduced. The low but persistent detection of plasma PTX indicates that PTX was control released from the system after intrapleural implantation. In a therapeutic efficacy study performed in the H460 orthotopic lung cancer model, gelatin sponges containing PLGA-PTX microspheres were placed in the pleural cavity as an adjuvant treatment after surgical resection of the primary lung tumour. Trans-lymphatic chemotherapy resulted in a significantly lower incidence of lymphatic tumour recurrence (20%) compared to no treatment and placebo control animals (100%). PLGA-PTX microspheres were seen in regional lymphatic tissue over 4 weeks after the sponge placement. It is concluded that the trans-lymphatic targeting drug delivery system described in this thesis may improve the control of lymphatic metastasis in lung cancer.
358

Lymphotrophic Nanoparticle-enhanced Magnetic Resonance Imaging for Nodal Clinical Target Volume Delineation in the Radiotherapy Treatment Planning of Pelvic Malignancies: Derivation of a Class Solution Nodal Clinical Target Volume

Dinniwell, Robert 30 November 2011 (has links)
Dextran-coated ultra-small, superparamagnetic, iron oxide particles (USPIO) have been proposed as magnetic resonance (MR) lymph node contrast agents. This thesis analyzed the topographic distributions of the pelvic and inguinal lymph nodes and quantified their spatial relations with the adjacent vascular system. We hypothesized that USPIO would facilitate identification of normal lymph nodes in a manner superior to that afforded by computed tomography or unenhanced MR, but using current clinically available scanners would be unlikely to identify microscopic nodal metastases. We have constructed a high quality nodal atlas describing probability distributions for lymph node number, size and position. Using this model, we then defined a generic three-dimensional nodal clinical target volume and a means of accurate delineation of this volume in a three-dimensional representation. This is the most quantitative assessment of the pelvic and inguinal lymphatics to date and will help to improve the successful targeting of lymph nodes for radiotherapy.
359

Lymphotrophic Nanoparticle-enhanced Magnetic Resonance Imaging for Nodal Clinical Target Volume Delineation in the Radiotherapy Treatment Planning of Pelvic Malignancies: Derivation of a Class Solution Nodal Clinical Target Volume

Dinniwell, Robert 30 November 2011 (has links)
Dextran-coated ultra-small, superparamagnetic, iron oxide particles (USPIO) have been proposed as magnetic resonance (MR) lymph node contrast agents. This thesis analyzed the topographic distributions of the pelvic and inguinal lymph nodes and quantified their spatial relations with the adjacent vascular system. We hypothesized that USPIO would facilitate identification of normal lymph nodes in a manner superior to that afforded by computed tomography or unenhanced MR, but using current clinically available scanners would be unlikely to identify microscopic nodal metastases. We have constructed a high quality nodal atlas describing probability distributions for lymph node number, size and position. Using this model, we then defined a generic three-dimensional nodal clinical target volume and a means of accurate delineation of this volume in a three-dimensional representation. This is the most quantitative assessment of the pelvic and inguinal lymphatics to date and will help to improve the successful targeting of lymph nodes for radiotherapy.
360

Controlled Trans-lymphatic Delivery of Chemotherapy for the Treatment of Lymphatic Metastasis in Lung Cancer

Liu, Jiang 28 July 2008 (has links)
Lymph node metastasis is a critical prognostic factor for lung cancer. Effective therapy to control lymphatic metastasis may improve survival. The work described in this thesis focuses on the development of a microparticulate lymphatic targeting system, which can be applied as an adjuvant therapy in the control of lymphatic metastasis in lung cancer. The study shows that intrapleural administered colloidal particulates are predominantly taken up by regional lymphatic tissue in rat models including healthy rats, rats bearing orthotopic lung tumours and rats following pneumonectomy. The effect of particle size on lymphatic particle distribution was examined by intrapleural administration of 111In-aminopolystyrene beads. Approximately 2 µm is a suitable size for intrapleural lymphatic targeting. Biodegradable polylactide-co-glycolide (PLGA) microparticles containing the anticancer agent paclitaxel (PTX) were subsequently formulated in the desired size by spray drying. PLGA-PTX microspheres were incorporated into a biodegradable and biocompatible gelatin sponge matrix to form an implantable lymphatic targeted drug delivery system. The system was characterized in vitro and its lymphatic targeting ability was examined in vivo. Fluorescence labeled microspheres embedded within the sponge were selectively taken up by regional lymphatics as the sponge matrix disintegrated following intrapleural implantation. A pharmacokinetic study showed that the total PTX exposure in lymphatic tissue was dramatically higher than that achieved through intravenous administration. The peak plasma drug concentration, which governs systemic toxicity, was significantly reduced. The low but persistent detection of plasma PTX indicates that PTX was control released from the system after intrapleural implantation. In a therapeutic efficacy study performed in the H460 orthotopic lung cancer model, gelatin sponges containing PLGA-PTX microspheres were placed in the pleural cavity as an adjuvant treatment after surgical resection of the primary lung tumour. Trans-lymphatic chemotherapy resulted in a significantly lower incidence of lymphatic tumour recurrence (20%) compared to no treatment and placebo control animals (100%). PLGA-PTX microspheres were seen in regional lymphatic tissue over 4 weeks after the sponge placement. It is concluded that the trans-lymphatic targeting drug delivery system described in this thesis may improve the control of lymphatic metastasis in lung cancer.

Page generated in 0.0446 seconds