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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.
541

A study of the predictive value of morphometric assessments in clinical outcome in ovarian epithelial malignancy

Palmer, Julia Elizabeth January 2007 (has links)
Quantitative pathology as a tool in gynaecological pathology is fairly new. Such techniques allow greater objectivity than histological grading, typing, and residual tumour estimation. This study aims to determine: whether basic morphometry data can predict outcome and chemotherapeutic response, whether newer semi-automated methods of tumour morphometry provide similar results to older methods, and whether advanced image analysis methods can offer further tumour outcome data in ovarian carcinoma. The study was performed on a well-selected group of serous ovarian carcinomas. Tumour outcome, survival and chemotherapeutic response, were investigated in 132 patients treated with the same platinum containing regimes. Traditional clinicopathologic parameters, p53 & Bcl2, mitotic activity index MAn and angiogenesis determinants were initially investigated. Semi-automated analysis, using immunohistochemically based techniques, were applied to estimate volume percentage epithelium (VPE) and nuclear morphometric parameters. Syntactic structure analysis including, minimum spanning tree, and neighbourhood features, was also investigated. Multivariate analysis revealed residual disease status, FIGO stage, MAl, VPE, equivalent nuclear diameter, and angiogenesis parameters to be strong prognosticators for overall and disease free survival. Residual disease status, VPE, nuclear length and angiogenesis parameters were found significant predictors of chemotherapy response. Angiogenesis parameters, as determined by semi-automated image analysis techniques, were found overall to be the strongest prognosticators. Morphometric data can predict outcome and chemotherapeutic response in ovarian serous carcinoma. Semi-automated morphometry techniques provide similar results to older methods, and advanced image analysis can offer further outcome data. The rationale for the application of semi-automated and automated detection is that it may provide an unbiased sampling of a lesion and possibly a more representative estimate of areas that a human expert might label. Such determined, quantitative pathological findings were found to have important value in predicting prognosis in ovarian carcinoma and, if not to supersede, certainly to add to classical prognostic factors.
542

Meningioma classification using an adaptive discriminant wavelet packet transform

Qureshi, Hammad A. January 2009 (has links)
Meningioma subtypes classification is a real world problem from the domain of histological image analysis that requires new methods for its resolution. Computerised histopathology presents a whole new set of problems and introduces new challenges in image classification. High intra-class variation and low inter-class differences in textures is often an issue in histological image analysis problems such as Meningioma subtypes classification. In this thesis, we present an adaptive wavelets based technique that adapts to the variation in the texture of meningioma samples and provides high classification accuracy results. The technique provides a mechanism for attaining an image representation consisting of various spatial frequency resolutions that represent the image and are referred to as subbands. Each subband provides different information pertaining to the texture in the image sample. Our novel method, the Adaptive Discriminant Wavelet Packet Transform (ADWPT), provides a means for selecting the most useful subbands and hence, achieves feature selection. It also provides a mechanism for ranking features based upon the discrimination power of a subband. The more discriminant a subband, the better it is for classification. The results show that high classification accuracies are obtained by selecting subbands with high discrimination power. Moreover, subbands that are more stable i.e. have a higher probability of being selected provide better classification accuracies. Stability and discrimination power have been shown to have a direct relationship with classification accuracy. Hence, ADWPT acquires a subset of subbands that provide a highly discriminant and robust set of features for Meningioma subtype classification. Classification accuracies obtained are greater than 90% for most Meningioma subtypes. Consequently, ADWPT is a robust and adaptive technique which enables it to overcome the issue of high intra-class variation by statistically selecting the most useful subbands for meningioma subtype classification. It overcomes the issue of low inter-class variation by adapting to texture samples and extracting the subbands that are best for differentiating between the various meningioma subtype textures.
543

Tumour-associated angiogenesis in the development and metastasis of human colorectal cancer

Rmali, Khaled Ali Ramadan January 2006 (has links)
The study has further shown that IL-1[Special character omitted] is a potential regulator of TEM-8 expression in tumours and that IL-1[Special character omitted] significantly induced the formation of capillary-like tubules from the HECV cells, accompanied by an increase in TEM-8 expression. Where as, elimination of TEM-8 by way of ribozyme transgene significantly decreased the formation of capillary-like tubules and the mobility of HECV cells. Moreover we have demonstrated that the vW domain together with trans-membrane domain of TEM-8 are the structural domain that are responsible for the tubule forming action of TEM-8, using expression construct in varying cell lines.
544

Exosomes : a source of novel disease biomarkers in bladder cancer

Welton, Joanne Louise January 2010 (has links)
The major aim of this thesis was to perform the first ever proteomics study on bladder cancer exosomes. Initially, exosomes were isolated from urine specimens but hypervariable yields and poor sample quality made proteomics analysis challenging. As an alternative approach, exosomes were isolated from HT1376 bladder cancer cells. Exosomes were purified by ultracentrifugation on a sucrose cushion, and preparations verified as high quality by immunoblotting, flow cytometry and electron microscopy. For global proteomics analysis, the sample was solubilised using SDS and DTT and subjected to LC-MALDI-TOF/TOF MS. We identified 353 proteins with high confidence and 63 of these have not previously been identified in other proteomics studies on human exosomes. Overrepresentation analysis demonstrated that the proteome was consistent with that of other exosomes with significant overlap with exosomes of carcinoma origin. Comparisons with the Gene Ontology database also highlighted strong associations with carcinoma of the bladder and other sites. A GeneGo generated protein interaction network highlighted c-Myc as a major node of protein interaction within this dataset. Several MS-identified proteins were confirmed as genuinely exosomally expressed using a combination of immunoblotting, flotation on continuous sucrose gradients, and flow cytometry. Expression was also verified in exosomes from a variety of sources, including urine. The data will aid our understanding of exosome biogenesis and function and may inform the development of urine exosome-based clinical tools in bladder cancer.
545

Exploring the role of CD44 in tamoxifen resistant breast cancer

Baruah, Bedanta Prakash January 2013 (has links)
Resistance to endocrine therapy in breast cancer is associated with poor prognosis. Cell models of acquired tamoxifen resistance have implicated altered growth factor receptor signalling, especially the ErbB family of receptor tyrosine kinases, in development of the accompanying aggressive phenotype. Microarray analysis of an in vitro wtMCF-7 based model of acquired tamoxifen resistance (‘Tam-R’) identified upregulation of CD44, a transmembrane glycoprotein, known to interact with ErbB receptors and influence breast cancer progression. We investigated the hypothesis that CD44 overexpression in Tam-R cells can modulate ErbB activity and promote an adverse phenotype. CD44 gene overexpression was validated by RT-PCR and its protein expression determined by Western blotting and immunocytochemistry. CD44 contribution to intracellular signalling and phenotype of Tam-R cells (migration, invasion and growth), both endogenous and in response to hyaluronan (HA), was determined using Western blotting, immunocytochemistry and functional assays including wound healing, Boyden chamber migration, Matrigel™ invasion and growth assays in the presence or absence of siRNA-mediated CD44 knockdown. Interactions between CD44 and ErbB receptors were investigated using immunofluorescence and immunoprecipitation. CD44 was overexpressed at gene and protein level in Tam-R versus wtMCF-7 cells and whilst this did not influence the endogenous phenotype of Tam-R cells, it enhanced their sensitivity to HA as evidenced by HA-induced MAPK, EGFR and HER2 activation and increased migration. HA-induced migration was attenuated following treatment with the MAPK inhibitor PD098059, gefitinib as well as trastuzumab. CD44 was found to associate with HER2 and HER3 at the cell surface whilst HA stimulation appeared to modulate ErbB dimerisation patterns. Our data suggest that CD44 overexpression sensitises tamoxifen-resistant cells to HA thereby modulating ErbB dimerisation and enhancing migration. These observations may have importance in vivo where the tumour microenvironment can provide a rich source of HA to promote the progression of tamoxifen-resistant tumours.
546

Prognostic factors influencing outcomes of specialist multidisciplinary treatment of oesophagogastric cancer in a UK cancer network

Reid, Thomas D. January 2012 (has links)
This thesis examines factors influencing the outcomes of patients receiving multidisciplinary stage-directed treatment for oesophagogastric cancer. The hypotheses tested were: 1.The TNM7 staging system is a more accurate prognostic tool for oesophageal cancer (OC) than TNM6. 2.Use of CT-PET upstages a significant number of patients with occult metastases. 3.OC recurrence patterns differ following definitive chemoradiotherapy (dCRT) and surgery, but overall recurrence rates and survival are comparable for advanced stage disease. 4.An involved circumferential resection margin (CRM+) following oesophagectomy is associated with poorer survival and its incidence can be reduced with neoadjuvant chemoradiotherapy. 5.Early enteral nutrition improves clinical outcomes following upper GI cancer resection. 6.Centralisation of oesophagogastric cancer (OGC) surgery in S.E. Wales is feasible and associated with improved clinical outcomes. Reclassification with TNM7 resulted in stage re-categorisation of 11.9% of OC patients. Multivariate analysis indicated only TNM7 prognostic group to be independently and significantly associated with survival. CT-PET upstaged OC M stage in 24.0% of patients. Loco-regional OC recurrence was commoner after dCRT (p<0.0001) but distant recurrence commoner after surgery (p=0.001). Disease-free survival was better after surgery for stage I (p=0.069) and II (p=0.011) but comparable with dCRT for stage III (p=0.878) and IV (p=0.710). CRM+ occurred in 38.0% of all OC patients, and 62.4% of pT3 patients. Multivariate analysis revealed lymphovascular invasion (p<0.0001) and CRM+ (p=0.002) were independently and significantly associated with disease-free survival. Multivariate analysis revealed EUS T stage (p<0.0001) and neoadjuvant chemoradiotherapy (p<0.0001) were independently associated with CRM+. Early enteral nutrition (EEN) was associated with reduced hospital stay (p=0.023) and less operative morbidity (p=0.044) than control management, due to fewer wound infections (p=0.017), chest infections (p=0.036) and anastomotic leaks (p=0.055). Following centralisation, OGC critical care (p<0.0001) and total hospital stay (p=0.037) were significantly reduced. Serious operative morbidity (Dindo-Clavien grade III+) decreased from 33.3% to 16.7% (p=0.066).
547

Molecular insight of the cAMP Responsive Element Binding Protein (CREB) in human breast cancer

Chhabra, Alok January 2012 (has links)
CREB, cAMP responsive element binding protein is a positive regulatory protein transcriptional factor, for genes including aromatase, an enzyme that converts androgens to oestrogens, c-fos, tyrosine hydroxylase and neuropeptides like somatostatin and enkephalin. The expression of aromatase is highly aberrant in human breast cancer and has been implicated in the disease progression. Aromatase expression in breast cancer tissue is directed mainly by promoters 1.3 and II. CRE1 and CRE2 are essential for cAMP induced promoter II activity. CRE binding protein (CREB) bound to this element (CRE) and that this interaction was enhanced in the presence of cAMP. Despite the extensive work on aromatase, little information is available on the expression and role of CREB in human breast cancer. The aim of this study was to investigate the molecular impact of CREB family of proteins on the aggressive nature of breast cancer cells and to investigate the expression pattern in breast cancer tissues in relation to tumour histopathological grade, stage, nodal status and the clinical outcome of the patients. In this study we examined the expression of CREB1 and ATFs (Activating transcription factors) in breast cancer cell lines using RT-PCR, which allowed us to design the strategy of in vitro experiments. Ribozyme knockdown technology was used to target the expression of CREB1 in a breast cancer cell line MDA-MB-231. Knockdown of CREB1 using ribozyme transgenes resulted in decrease in in vitro cell growth and invasiveness in breast cancer cells. The results presented here demonstrate that the level of CREB-1 and ATFs in breast cancer patients was elevated. The study results presented here revealed a significant link between CREB and mortality, in that high levels are associated with shorter disease free survival and interestingly we found significantly low levels of ATFs in patients with poor prognosis, metastatic disease and nodal involvement. We conclude that the level of CREB-1 and ATFs are aberrantly expressed in human breast cancer which may be associated with disease progression in breast cancer patients and has significant bearing to the clinical outcome of the patients. Over-expression of aromatase in adipose tissue surrounding breast tumour could arise through increase in both CREB expression and CREB transcriptional activity. Inhibition of CREB activity could inhibit aromatase expression and hence decrease oestrogen production in breast tissue. An understanding of the molecular mechanisms of expression of CREB, together with aromatase between non-cancerous and cancerous breast tissue at both transcriptional and translational levels may help in the design of a therapy based on suppressing aromatase expression in breast cancer tissues.
548

Wnt signalling in endocrine resistant breast cancer

Micallef, Rachel Antonia January 2012 (has links)
Wnt signalling components are reported to be deregulated in breast cancer but the contribution of this pathway in endocrine resistance is less clearly defined. Endocrine resistance is an important clinical challenge affecting up to a quarter of all breast cancer patients and is associated with a poorer clinical prognosis. This project focussed on exploring the role of Wnt signalling in endocrine resistant breast cancer cell models. Wnt pathway elements were deregulated in the acquired tamoxifen resistant cell line (Tam-R) compared to tamoxifen sensitive parental cells (MCF-7), with changes supportive of Wnt signalling activation in this tamoxifen resistant model apparent from Affymetrix HGU-133A gene microarray data and Western blot analysis. In contrast, Wnt signalling appeared to be suppressed based on Affymetrix data for MCF-7 cells treated with oestradiol for 10 days, with equivocal changes in MCF-7 cells treated with tamoxifen for 10 days or a faslodex resistant cell model (Fas-R). Excitingly, Tam-R cells were also more sensitive than MCF-7 cells to pharmacological manipulation of Wnt signalling. While Wnt activation using Wnt3a and LiCl did not affect cell growth or migration, inhibition of Wnt signalling usingIWP2, PNU 74654 and iCRT14 suppressed Tam-R cell growth and migration. There is mounting evidence of cross talk between Wnt and EGFR signalling in breast cancer, and EGFR activity is upregulated in Tam-R cells. The project’s findings tentatively supported cross-talk between the two signalling pathways in this model. Thus, targeting of the Wnt pathway alongside EGFR blockade was superior in suppressing cell growth and migration in Tam-R cells. The effect appeared to be more pronounced when Wnt signalling was inhibited at the nuclear level using iCRT14. Collectively, these data suggest that Wnt signalling may play an important role in tamoxifen resistance where it may offer an opportunity for more effective therapeutic intervention to control relapse and associated tumour aggressiveness.
549

Methylation of human papillomavirus DNA : biological significance and clinical utility

Bryant, Dean January 2012 (has links)
DNA methylation helps regulate transcriptional activity and is widely studied in cancer biology. This investigation aimed to establish the significance of Human Papillomavirus (HPV) DNA methylation in HPV-associated disease both in terms of basic biology and as a potential biomarker. Assays to assess DNA methylation and gene expression were developed and evaluated. Pyrosequencing was used to assess DNA methylation of four regions of the HPV16 genome (E2, L1/L2, enhancer, promoter). Gene expression was assessed using quantitative PCR with assays for E2, E6 and E7. HPV integration was assessed using Detection of Integrated Papillomavirus Sequences (DIPS). The relationship between HPV methylation, gene expression and integration was explored in vitro and in vivo using cell cultures and clinical cohorts. A variety of sample materials were used including short term and immortal cell lines, cervical cancer biopsies, cytology samples and Vulval Intraepithelial Neoplasia (VIN) biopsies. In general, hypermethylation of the HPV genome was associated with low HPV gene expression and the presence of integrated HPV genomes. To better understand the potential clinical utility of HPV DNA methylation, the relationship between HPV DNA methylation and various stages of cervical disease was determined. The HPV genome was progressively hypermethylated with increasing severity of cervical disease and certain regions of the HPV genome were more affected than others. A longitudinal study was also performed in order to determine a relationship between HPV methylation and clinical outcome. Differences in HPV methylation among patients who had persistent HPV infection and low grade disease, persistent infection and high grade disease and patients that cleared HPV infections were observed. Throughout the study the potential application of a HPV biomarker was considered and the correct biomarker design procedures were referred to. Several of the early biomarker development steps were successfully achieved.
550

Human papillomavirus integration : the mechanism(s) behind the high-risk associated with this event and cervical disease progression

Raybould, Rachel January 2013 (has links)
Cervical cancer is the second most common cancer among women worldwide. Infection with Human Papillomavirus (HPV) is essential but not the only contributing factor in cervical cancer development. HPV integration is reported to be present in over 80% of cervical cancers and disruption of HPV genome through integration leads to high levels of HPV oncogene expression. DNA damage and repair pathways are thought to induce HPV integration since HPV is detected at fragile sites in the human genome. There is controversy as to whether integration is an early or late event in cervical oncogenesis and there are no published studies to date that have investigated HPV integration using sensitive, DNA based, techniques at the nucleotide level in cervical precancers. This study aimed to test the hypothesis that integration is an early event in cervical neoplasia and episomal loss causes malignant transformation through transcription of integrated HPV. Also, this study served to pilot whether HPV integration can predict high-grade cervical disease in women with cytological abnormalities with an aim to improve current cervical screening methods. Assays to detect integration and E2 as a marker of episomal state were developed for HPV16, HPV18 and HPV45 and applied to cervical smears and biopsies from women with varying disease grades. The data presented in this thesis highlight that integration may not be essential for cervical cancer progression and different modes of disease progression may exist between young women and older women. Integration was detected at chromosome fragile sites but was more prevalent at SINE or LINE repeat elements; this implies a role for retroelements in the mechanism of integration. Finally, the data here suggest that integration induces a unique selective process in each individual and clonal selection may arise due to altered HPV oncogene expression and/or disruption to human gene expression.

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