Women with breast cancer without local metastasis to the axillary lymph nodes (axillary lymph node-negative, ANN) have a good prognosis. However, 20 to 30% of patients with ANN breast cancer will still experience recurrence and distant metastases. Lymphatic invasion (LVI) is an important prognostic factor for ANN breast cancer. Zinc fingers and homeoboxes 1 (ZHX1) was identified as a candidate gene involved in LVI and associated with early recurrence of ANN breast cancer. I examined expression of ZHX1 in breast cancer cell lines and ANN breast tumour samples and discovered that it is expressed at variable levels. I also investigated ZHX1 copy number and determined that amplification does not appear to be a mechanism of its over-expression. From bioinformatic and proteomic analyses, ZHX1 was discovered to potentially be phosphorylated. Overall, these studies suggest that ZHX1 may be involved in ANN breast cancer.

Intraocular pressure (IOP) is the most important risk factor for glaucoma development and progression. Most anti-glaucoma treatments aim to lower IOP by enhancing aqueous humor drainage from the eye. Aqueous humor drainage occurs via well-characterized trabecular meshwork (TM) and uveoscleral (UVS) pathways, and the recently described ciliary lymphatics. The relative contribution of the lymphatic pathway to aqueous drainage is not known. We developed a sheep model to quantitatively assess lymphatic drainage along with TM and UVS outflows. Following intracameral injection of 125I-bovine serum albumin (BSA), lymph and blood samples were continuously collected. Lymphatic and TM drainage were quantitatively assessed by measuring 125I-BSA recovery. This quantitative sheep model enables assessment of relative contributions of lymphatic drainage (1.64% ± 0.89%), TM (68.86% ± 9.27%) and UVS outflows (19.87% ± 5.59%), and may help to better understand the effects of glaucoma agents on outflow pathways.

Women with breast cancer without local metastasis to the axillary lymph nodes (axillary lymph node-negative, ANN) have a good prognosis. However, 20 to 30% of patients with ANN breast cancer will still experience recurrence and distant metastases. Lymphatic invasion (LVI) is an important prognostic factor for ANN breast cancer. Zinc fingers and homeoboxes 1 (ZHX1) was identified as a candidate gene involved in LVI and associated with early recurrence of ANN breast cancer. I examined expression of ZHX1 in breast cancer cell lines and ANN breast tumour samples and discovered that it is expressed at variable levels. I also investigated ZHX1 copy number and determined that amplification does not appear to be a mechanism of its over-expression. From bioinformatic and proteomic analyses, ZHX1 was discovered to potentially be phosphorylated. Overall, these studies suggest that ZHX1 may be involved in ANN breast cancer.

The lymphatic system plays an important role in fluid and protein balance within the interstitial spaces. Its dysfunction could result in a number of debilitating diseases, namely lymphedema. Lymphatic vessels utilize both intrinsic and extrinsic mechanisms to pump lymph. Intrinsic pumping involves the active contraction of vessels, a phenomenon that is regulated in part by nitric oxide (NO) produced by lymphatic endothelial cells (LECs). NO production by arterial endothelial cells has been shown to be sensitive to both shear stress and stretch. Therefore, because of the unique mechanical environment of the LECs, we hypothesize that mechanical forces play an important role in regulation of the lymphatic pumping. Parallel-plate flow chambers and indenter-based cyclic stretch devices were constructed and used to apply mechanical loads to LECs. In addition, high-throughput micro-scale channels were developed and tested for shear experiments to address the need to increase the productivity and high- resolution imaging. Twenty-four hours treatment of LECs with different shear stress conditions showed a shear-dependent elevation in NO production. Moreover, 2.5 folds increase in cumulative NO was observed for stretched cells compared to the unstretched cells over six hours period. In conclusion, the upregulation observed in NO production under mechanical stimuli suggest new regulatory mechanisms that can be pharmaceutically targeted. These results provide an unprecedented insight into lymphatic pumping mechanism.

Ph.D.

To maintain human health, the lymphatic system requires a structurally and functionally sound network of lymph vessels to absorb lipid-based nutrients, preserve extracellular fluid homeostasis, and mediate immune responses. Aside from lymphedema, investigations in the past few decades have found that impairment of the lymphatic vasculature is also involved in processes such as inflammation, tumor metastasis, fat metabolism, and obesity. However, despite a long history of study and rekindled vigor in the field of lymphatic vascular research, our knowledge of lymph vessel development and physiology is still quite limited. Recently, mutations in a protein family known as connexins (Cxs) were identified as the cause of lymphatic dysfunction in some cases of inherited lymphedema. This dissertation explores the role of primarily two specific connexins, Cx37 and Cx43, and the transcription factor Foxc2 in the morphogenesis and function of the lymphatic vasculature in mice. To accomplish this, phenotypic characterization of mice with genetic deficiencies (knockout mice) in Cx37, Cx43, and/or Foxc2 was performed principally via necropsy, histological techniques (immuno-fluorescence microscopy and H&E staining), and Evans blue dye (EBD) injections. Developmental abnormalities were found in lymphatic vascular growth, patterning, and remodeling in mice lacking Cx37, Cx43, Foxc2 or a combined deficiency of these proteins. Reductions or complete loss of lymphatic valves were a common finding in mice lacking one or more of these proteins. These valve deficits underlay lymphatic insufficiencies that resulted in lymphedema and chylothorax in some genotypes. Foxc2 was found to be a regulator of Cx37 expression. Moreover, Foxc2 was also dependent on Cx37 function for proper morphogenesis of lymph vessels. These findings pertaining to the expression of connexins in the lymphatic vasculature, their role in lymphatic valvulogenesis, and the interdependence of Cx37 and Foxc2 during lymph-vascular development represent my original contributions to human knowledge.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xiv, 126 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 123-126).

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available online.

Thesis (Ph.D. in Reproductive Sciences) -- University of Colorado Denver, 2007. / Typescript. Includes bibliographical references (leaves 125-140). Free to UCD affiliates. Online version available via ProQuest Digital Dissertations;