Thesis (M.Sc.)--Memorial University of Newfoundland, Faculty of Medicine, 2000. / Typescript. Bibliography: leaves 92-100.

Techn. University, Diss., 2005--München.

Dentre os diversos fatores que provocam diminuição no desempenho reprodutivo, a degeneração testicular térmica é o motivo mais freqüente de baixa fertilidade em Bos taurus no Brasil. Baseados nos efeitos sobre a secreção de hormônios hipofisários e gonadais, o GH vem sendo estudado para o tratamento da infertilidade masculina. Um delineamento experimental tipo blocos ao acaso utilizou dezesseis touros adultos submetidos a 4 tratamentos em esquema fatorial 2x2 (0 e 96 horas de insulação testicular, 0 e 1,2 mg bST/kg PV), com o objetivo de testar os efeitos da bST no tratamento de touros submetidos a insulação testicular. Motilidade, alterações de acrossoma, defeitos de cauda e cabeça, gota protoplasmática proximal e defeitos espermáticos totais aumentaram em conseqüência da insulação testicular. As concentrações seminais de Testosterona foram temporariamente diminuídas em resposta a insulação testicular. A ocorrência de gota protoplasmática distal, anomalias de peça intermediária e concentrações seminais de IGF1 não foram afetadas pela insulação testicular. A somatotropina recombinante bovina não afetou as características espermáticas ou concentrações seminais de Testosterona e IGF1. / Testicular heat degeneration is the most common cause of poor fertility of Bos taurus bulls in the tropics. The Growth Hormone has been studied in man infertility treatment with some progress. A randomly blocks experimental design used 16 mature bulls allotted in 4 treatments in a 2x2 factorial arrangement (0 e 96 hours of scrotal insulation, 0 e 1,2 mg bST/kg BW) was performed to asses the effects ob bulls submitted to scrotal insulation. Motility, abnormal acrosome, tail and head defects, proximal droplet, and abnormal sperm increased, and seminal plasma Testosterone was temporally increased in response to scrotal insulation. Distal droplet, midpiece and seminal plasma IGF1 were not affected by bST. The bST did not affect sperm characteristics or seminal Testosterone and IGF1.

Fluid pressures regulate endothelial cell (EC) tubulogenic activity involving fibroblast growth factor 2 (FGF-2) and its receptor, FGF receptor 2 (FGFR2). Our lab has recently shown that sustained 20 mmHg hydrostatic pressure (HP) upregulates EC sprout formation in a FGF2-dependent fashion. This upregulation of sprout formation may be due to enhanced FGF-2 / FGFR2 interactions in the presence of 20 mmHg HP. We hypothesize that exposure of ECs to 20 mmHg sustained HP enhances FGF-2 binding kinetics. We used a custom hydrostatic pressure system, immunofluorescence, and FACS to quantify FGF-2 binding by ECs in the absence or presence of a range of HPs for 30 minutes. Relative to cells maintained under control pressure, ECs exposed to 20, but neither 5 nor 40 mmHg, displayed a significant increase in binding affinity to FGF-2. EC binding of VEGF-A, another angiogenic growth factor, was unaffected by similar pressure stimuli. Additional studies showed that pressure-selective FGF-2 binding was independent of FGFR2 surface expression. These results implicate the FGF-2 axis in the pressure-sensitive, magnitude-dependent angiogenic processes which we have previously described. The present study provides novel insight regarding the involvement of FGF-2 signaling and interstitial pressure changes in various microvascular physiological and pathobiological processes.

No description available.

Receptor tyrosine kinases (RTK) are key regulators of growth, differentiation and survival of epithelial cells and play a significant role in the development and progression of cancers derived from these tissues. In malignant cells, these receptors and their downstream signalling pathways are often deregulated, leading to cell hyper-proliferation, enhanced cell survival and increased metastatic potential. Furthermore, endothelial expressed RTKs regulate tumor angiogenesis allowing for tumor growth and maintenance by promoting their vascularization. Epithelial malignancies such as squamous cell carcinomas (SCC), non-small cell lung (NSCLC) and malignant mesotheliomas have very limited treatment options when presenting as metastatic disease. RTKs, particularly the epidermal growth factor (EGFR) and the vascular endothelial growth factor (VEGFR) receptors, have been shown to play significant roles in the pathogenesis of these tumor types. Statins are potent inhibitors of HMG-CoA reductase, the rate limiting enzyme of the mevalonate pathway, that are widely used as hypercholesterolemia treatments. The mevalonate pathway produces a variety of end products that are critical for many different cellular pathways, thus, targeting this pathway can affect multiple signalling pathways. Our laboratory has previously shown that lovastatin can induce tumor specific apoptosis especially in SCC and that 23% of recurrent SCC patients treated with lovastatin as a single agent showed disease stabilization in our Phase I clinical trial. Subsequently, our lab was able to demonstrate that lovastatin in combination with gefitinib, a potent inhibitor of the EGFR showed co-operative cytotoxicity when combined (Chapter 2). Furthermore, the pro-apoptotic and cytotoxic effects of these agents were found to be synergistic and to be manifested in several types of tumor cell lines including SCC, NSCLC and glioblastoma. I was able to expand upon these important findings and demonstrated that lovastatin, through its ability to disrupt the actin cytoskeleton, inhibited EGFR dimerization and activation (Chapter 3). This novel mechanism targeting this receptor has clinical implications as lovastatin treatment combined with gefitinib showed co-operative inhibitory effects on EGFR activation and downstream signalling. The RTK family of proteins share similar features with respect to activation, internalization and downstream signalling effectors. I further demonstrated that lovastatin can inhibit the VEGFR-2 in endothelial cells and mesotheliomas, where VEGF and its receptor are co-expressed driving their proliferation, and induces synergistic cytotoxicity in mesothelioma cells in combination with VEGFR-2 tyrosine kinase inhibitors (Chapter 4). These findings suggest that statins may augment the effects of a variety of RTK inhibitors in a similar fashion representing a novel combinational therapeutic approach in a wide repertoire of human cancers. More importantly, based on this work, we initiated a Phase I/II study evaluating high dose rosuvastatin and the EGFR inhibitor tarceva in SCC and NSCLC patients at our institute. This clinical evaluation will provide invaluable data that will play a role in developing this novel therapeutic strategy. Together, the work embodied in this thesis provides a model for the regulation of EGFR/VEGFR-2 activation and signalling by targeting the rho family of proteins that demonstrates a novel mechanism that can be exploited to refine current therapeutic paradigms.

No description available.

No description available.

Breast cancer is a leading cause of cancer death of women in the U.S. today. Members of the family of insulin-like growth factors (IGFs) are proposed to play a major role in the development and subsequent uncontrolled proliferation of breast cancer cells. Insulin-like growth factor-I (IGF-I) is known to be a potent mitogen for mammary epithelial cells. IGF-I acts by binding to cell surface receptors, thereby stimulating a cascade of events leading to cell division. In the interest of interrupting the effect of IGF-I on cancerous mammary epithelial cells, an understanding of how IGF-I behaves in the presence of other extracellular components is needed. This study examines the IGF-I response of SV40-IGF-I, an immortalized bovine mammary epithelial cell line which secretes IGF-I constitutively. The microphysiometer allows real-time sampling of cellular activity by measuring the excretion of protons from a sample of cells stimulated by IGF-I binding. The contributions of other factors in enhancing or suppressing stimulation can be compared by examining the pH response of cells exposed to IGF-I in the presence of these factors. We present data showing the stimulatory effect of IGF-I in a dose dependent manner on the SV40-IGF-I cell line. In addition, we compare IGF-I stimulation with stimulation by long R3IGF-I, a substituted analogue of IGF-I having a reduced binding affinity for the IGF binding proteins. We examine the effect of insulin-like binding protein-3 (IGFBP-3) both in the presence and absence of IGF-I, finding no IGF-I independent effect in the rapid binding experiment and no effect on stimulation of IGFBP-3 pre-incubated cells by subsequent IGF-I challenge. This is of particular interest due to recent work demonstrating an IGF-independent IGFBP-3 response in a number of cell lines. Binding studies to correlate with the rapid binding stimulation show binding of the IGFBP-3 molecule with high affinity to a small number of surface receptors on the SV40-IGF-I cell. Analysis of the extracellular environment and the components contributing to the binding of IGF-I to the cell membrane receptor will provide information for the development of interventions to slow or interrupt the process of IGF-I binding and therefore cancer growth. Optimization of the Cytosensor(r) Microphysiometer System for the (transfected) SV40-IGF-I and the (parental) MAC-T cell lines was achieved to continue comparison studies of autocrine and paracrine stimulation of bovine mammary epithelial cells by IGF-I. This work was supported by the Whitaker Foundation Biomedical Engineering Grant. / Master of Science

Diss. (sammanfattning) Linköping : Univ., 2004. / Härtill 6 uppsatser.