<p>Abstract</p><p>During embryonic development many structures crucial for breathing and eating arise from the pharyngeal and anterior foregut epithelium (FGE), which contains the oral ectoderm and the foregut endoderm. Proper differentiation and signaling within and from this epithelial tissue is necessary for the development of the mandible, the esophagus, and the trachea. Many birth defects occur in these structures that greatly disrupt the ability of affected infants to breathe and eat. This dissertation investigates the importance of the pharyngeal and anterior FGE in mandible and foregut development. </p><p>The most rostral portion of the pharyngeal epithelium contributes to the development of the mandible. At embryonic day 10.5 the mandible is a bud structure, composed of neural crest-derived mesenchyme and core mesoderm surrounded by pharyngeal epithelium. The mesenchyme needs to receive Hedgehog signaling for mandible development, but the epithelial tissue that signals to the mesenchyme has not been identified in mammals. Data presented in Chapter 2 show that Sonic Hedgehog is necessary at two distinct stages of mandible development by using a tissue specific genetic ablation to remove Sonic Hedgehog from the pharyngeal endoderm. First, we show that Sonic Hedgehog promotes cell survival prior to cartilage differentiation through immunostaining for Caspase-9, an apoptosis marker. Second, a rescue of early cell death with the p53 inhibitor pifithrin-&#945; shows that Sonic Hedgehog is necessary for cartilage condensation and differentiation later in development. Without cartilage differentiation the mandible is unable to elongate properly and hypoplasia occurs.</p><p>Caudal to the pharyngeal epithelium is the anterior FGE, which develops into the larynx, esophagus and trachea. The anterior FGE is a single endodermal tube at E9.5 and by E11.5 compartmentalizes into two distinct tubes: the esophagus and trachea. While the signaling pathways involved in proper compartmentalization of the foregut are well studied, nothing is known about the cellular behaviors that drive this complex event. One important event during foregut compartmentalization is the establishment of dorso-ventral patterning, which is necessary for separation to occur. To elucidate the importance of dorso-ventral patterning, we take advantage of two genetic mouse models with disrupted patterning, an activation of and a removal of &#946;-catenin in the ventral foregut endoderm. Data presented in Chapter 3 show that &#946;-catenin is important for epithelial pseudostratification and the establishment of a region of double-positive cells at the dorso-ventral midline through close examination of epithelial morphogenesis at E10.5 prior to compartmentalization. This data has established two mouse models for studying changes in epithelial morphology during foregut compartmentalization. In total, this body of work details how signals originating in the pharyngeal and anterior foregut epithelium regulate both mesenchymal and epithelial behaviors during mandible and foregut development.</p> / Dissertation

The epidemiology of head and neck squamous cell carcinomas (HNSCC), primarily those of the oropharynx, has changed dramatically over the last two decades. Specifically, HNSCC appears to be a distinct entity that is related to infection by human papilloma virus (HPV)(Vokes et al., 2015) (Fakhry et al., 2008). Moreover, the incidence of HPV-associated oropharyngeal (OP) cancers is rising, likely as a consequence of changing life styles and sexual behaviors. These tumors appear to be biologically and clinically distinct from other HNSCC tumors affecting predominantly middle-aged white men having no or only a brief history of tobacco consumption. The cell cycle regulatory protein, p16, is usually over expressed in HPV-OPSCC, and its detection using immunohistochemistry and in situ hybridization is a reliable surrogate marker for the disease (Ang et al., 2012). When compared to traditional head and neck cancer that is associated with the repeated insult of tobacco use, HPV-related OPSCC has a favorable natural history and is more responsive to treatment. As a result, patients with this cancer have improved long-term survival and consequently are more likely to experience chronic therapy-induced morbidity (Ang et al., 2012). The purpose of this thesis is to provide a comprehensive review of the molecular mechanisms that underlie HPV-mediated OPSCC, and the licensed prophylactic HPV vaccinations available, and to discuss the current thoughts on whether to deescalate potentially damaging treatments in these patients.

<p>Bacterial tubulin homolog FtsZ assembles straight protofilaments (pfs) that form the scaffold of the cytokinetic Z ring. These pfs can adopt a curved conformation forming a miniring or spiral tube 24 nm in diameter. Tubulin pfs also have a curved conformation, forming 42 nm tubulin rings. We have previously provided evidence that FtsZ generates a constriction force by switching from straight pfs to the curved conformation, generating a bending force on the membrane. In the simplest model the membrane tether, which exits from the C terminus of the globular FtsZ, would have to be on the outside of the curved pf. However, it is well established that tubulin rings have the C terminus on the inside of the ring. Could FtsZ and tubulin rings have the opposite curvature? In the present study we explored the direction of curvature of FtsZ rings by fusing large protein tags to the N or C terminus of the FtsZ globular domain. FtsZ with a protein tag on the N terminus did not assemble tubes. This was expected if the N terminus is on the inside, because the protein tags are too big to fit in the interior of the tube. FtsZ with C-terminal tags assembled normal tubes, consistent with the C terminus on the outside. The FN extension was not visible in negative stain, but thin section EM gave definitive evidence that the C-terminal tag was on the outside of the tubes. This has interesting implications for the evolution of tubulin. It seems likely that tubulin began with the curvature of FtsZ, which would have resulted in pfs curving toward the interior of a disassembling MT. Evolution not only eliminated this undesirable curvature, but managed to reverse direction to produce the outward curving rings, which is useful for pulling chromosomes.</p> / Dissertation

Adrenomedullin (AM) and pro-adrenomedullin N-terminal 20-peptide (PAMP) are peptides recently identified from a rat pheochromocytoma. Both of these peptides are cleavage products of pre-pro-AM. Specific receptors for AM have been characterised in several species, including rat and human. The aim of this study was to investigate the role of PAMP and AM in the adrenal cortex. Using an intact rat capsule preparation PAMP was shown to cause a dosedependent increase in aldosterone secretion, which was accompanied by a dosedependent increase in cAMP release. The effects of PAMP were inhibited by HA1004, an inhibitor of protein kinase A. These results suggest that PAMP stimulates aldosterone secretion from the zona glomerulosa via cAMP. Ligandbinding studies were then used to demonstrate the presence of specific PAMP receptors. Two classes of receptor were shown in the rat zona glomerulosa (Kdi 1.9 nmol/l, Bmai, 53 fmol/mg protein; Kd2 10 nmol/l, Bmac,2 225 fmol/mg protein). At the latter receptor PAMP was displaced by AM. None of the other competitors tested displaced PAMP. Using the H295R cell line, both PAMP and AM were shown to increase aldosterones ecretion in a dose-dependenmt anner. In both casesa corresponding dose-dependent increase in cAMP was observed. Both PAMP and AM also effected a dose dependent increase in cortisol secretion. mRNA analysis showed that the gene encoding pre-pro-AM was expressed in these cells. Immunocytochemistry confirmed that these cells were producing both PAMP and AM. Immunocytochemistry and mRNA analysis also revealed that both of the candidate receptors for AM, L1 and CRLR, are expressed in this cell line. Taken together these findings demonstrate that both AM and PAMP are produced by adrenocortical cells and likely to have a role in regulating adrenal steroidogenesis. Furthermore, these studies suggest the presence of a specific PAMP receptor in the rat adrenal gland.

<p> Most of the colon cancer patient tumors progress to metastases, despite undergoing surgical resection or adjuvant chemotherapy. Predicting which patients will progress to metastases has been extremely challenging. There is an urgent need to identify early novel prognostic biomarkers that can early on predict the patient outcome. Vitamin C has been shown to have a pro-oxidant effect on cancer that enhances tumor growth and survival. Vitamin C is transported into mammalian cells via two isoforms of sodium-dependent vitamin C transporters (SVCTs), SVCT1 and SVCT2. The expression and clinical implications of SVCTs in tumor tissues could help us investigate its prognostic value in predicting patient outcome. In this report, we performed immunohistochemistry to determine SVCT1 and SVCT2 expression on primary tumors of 178 colon cancer patients. Colon cancer cells selectively expressed SVCT2 but not SVCT1. Moreover, poorly differentiated and metastatic tumors correlated with higher SVCT2 expression. Furthermore, increased SVCT2 expression was associated with shorter progression-free survival in patients with no or little lymph node invasion. We confirmed that SVCT2 could be an early stage prognostic biomarker that can predict colon cancer disease progression and survival.</p><p>

The Game of life is probably the most famous cellular automaton. Life shows all the characteristics of Wolfram's complex Class N cellular automata: long-lived transients, static and propagating local structures, and the ability to support universal computation. We examine in this thesis questions about the geometry and criticality of Life. We find that Life has two different regimes with different dimensionalities. In the small scale regime Life shows a fractal dimensionality with Ds = 0.658 and in the large scale regime D1 = 2.0, suggesting that the objects of Life are randomly distributed. We find that Life differentiates between different spatial directions in the universe. This is surprising because Life's transition rules do not show such a differentiation. We find further that the correlations between alive cells extend farthest in the active period and that they decrease in the glider period, suggesting that Life is sub-critical. Finally, we find a size-distribution of active clusters which does not depend on the lattice size and amount of activity, except for the largest clusters. We suggest that this result also indicates that Life is sub-critical.

1v. (various paging) ; / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (D.Sc.)--University of Adelaide, Dept. of Microbiology, 1976

viii, 139, xii leaves : ill. ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology, 1974

Intracellular signaling cascades can no longer be viewed as linear pathways that relay and amplify information. Often, components of different pathways interact, resulting in signaling networks. The interactions of different pathways and the dynamic modulation of the activities of the components within signaling pathways can create a multitude of biological outputs. The cell appears to use these pathways as a way of integrating multiple inputs to shape a uniquely defined output. These outputs allow the cell to respond to and adapt to an ever-changing environment. Understanding how biological systems receive, process and respond to complex data inputs has important implications for the design and utilization of sensors for a variety of applications, including toxicology, pharmacology, medical diagnostics, and environmental monitoring. This study uses the elicitor sets method, which is an experimental framework designed to monitor information flows through signal transduction pathways. The elicitor set approach has been used to derive mechanistic interpretations from the action of Phenylmethylsulfonyl Fluoride (PMSF), a serine protease inhibitor and nerve agent analog. The elicitor panel comprises of signal transduction network effectors namely forskolin, clonidine, cirazoline and H89, each of which targets the signaling pathway at known specific points. The elicitor set experiments enable compartmentalization of the cAMP signaling pathway, examining the role played by each segment and identifying possible cross-talk mechanisms. Our experiments substantiate that selection of adenyl cyclase as the reference node and 10 [mu]M forskolin as the primary elicitor, segments the upper portion of the G-Protein Coupled Receptor (GPCR) pathway associated with the G[sub q] and G[sub i] proteins. Application of the secondary elicitors, 100 nM clonidine (a2-adrenergic receptor agonist), 1 pM and 100 pM cirazoline (al-adrenergic receptor agonists), and 1 [mu]M and 100 [mu]M H-89 (PKA inhibitor) fortifies the decoupling, as the system is unresponsive to clonidine and cirazoline in the presence of forskolin, while continuing to respond to H-89. Exposure of the cells to 1 mM PMSF subsequent to forskolin addition restricted the quantifiable impact of PMSF to regions of the signaling pathways below adenyl cyclase. Triggering the system by use of secondary elicitors augmented the information resolution which is reinforced by the increased sensitivity of cells to 100 [mu]M H-89 that acts at an important checkpoint below adenyl cyclase. / Graduation date: 2004

Thesis (Ph. D.)--University of Chicago, Dept. of Computer Science, March 1999. / Includes bibliographical references. Also available on the Internet.