ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / This paper investigates the performance of a multiple-input multiple-output (MIMO) digital communication system, when the transmitter is located on a spinning vehicle. In particular, a 2x2 MIMO system is used, with Alamouti coding at the transmitter. Both Rayleigh and Rayleigh plus line-of-sight, or Rician, models combined with a deterministic model to simulate the channel. The spinning of the transmitting vehicle, relative to the stationary receive antennas, modulates the signal, and complicates the decoding and channel parameter estimation processes. The simulated system bit error rate is the primary performance metric used. The Alamouti channel code is shown to perform better than the maximal ratio receiver combining (MRRC) and single receiver (2x1) system in some circumstances and performs similarly to the MRRC in the broadside case.

A discussion of reward, coercive, expert, legitimate, and referent power bases was the initial focus of this research. A review of the power sources literature suggested that vertical integration within a channel of distribution was a crucial precursor to develop a structure to facilitate the use of power without creating a significant conflict among channel participants. Elements of transaction cost analysis (TCA) were offered as being suitable for determining the existing level of vertical integration among respondent firms. Accordingly, the purpose of this study was to develop a tentative model to determine proper use of power within varying levels of vertical integration.

by Chu Yu Lun, Stanley [and] Kwong Kin Hing, Edmund. / Includes bibliographies / Thesis (M.B.A.)--Chinese University of Hong Kong, 1984

by Wong Chun-Ming. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 52-53). / ABSTRACT --- p.i / TABLE OF CONTENTS --- p.ii / CHAPTER / INTRODUCTION --- p.1 / Scope of study --- p.2 / Research Objectives --- p.3 / Methodology --- p.4 / LITERATURE REVIEW --- p.6 / MACRO-ENVIRONMENT --- p.10 / DISTRIBUTION SYSTEMS IN CHINA --- p.14 / TRADITIONAL DISTRIBUTION SYSTEM IN CHINA --- p.14 / The Pre-reform Structure: - The Three Tier system --- p.14 / Reform of Distribution System --- p.15 / The Reform of Wholesale System --- p.15 / Phase I: Abolition of State Monopoly --- p.15 / Phase II: Reforms in Pricing and Distribution --- p.16 / Phase III: Multi-ownership Type --- p.15 / The Reform of Retail System --- p.19 / Recent Development in Retail System --- p.20 / Problems of Traditional Distribution System --- p.22 / NEWLY DEVELOPED DISTRIBUTION CHANNELS --- p.25 / Direct Outlets --- p.25 / Direct Marketing in China --- p.25 / Foreign Agents Operating in China --- p.26 / SELECTION OF A DISTRIBUTOR --- p.27 / Types of Distributors in China --- p.27 / Where to Find a Distributor --- p.29 / Evaluating Potential Distributors --- p.30 / CASE STUDIES --- p.33 / Tobacco Manufacturer --- p.33 / Beverage Manufacturer --- p.37 / Watches Manufacturer --- p.40 / THE EXPERIENCE OF CASE STUDIES --- p.44 / CONCLUSIONS --- p.49 / BIBLIOGRAPHY --- p.52

Calcium plays an essential role in the physiology and biochemistry of many biological functions, including excitation-contraction coupling, neuronal signaling, and fertilization. In mammals, the calcium content in various tissues, organs, and cell types is tightly regulated to maintain homeostasis. A chief process controlling calcium levels is absorption of the ion from the lumen by epithelial cells that line organs including the intestines and kidney. Calcium entry at the apical membrane constitutes the first step of epithelial calcium absorption. Two highly calcium-selective transient receptor potential vanilloid (TRPV) channels, TRPV5 and TRPV6, are the pore-forming subunits responsible for epithelial calcium entry in kidney and intestine, respectively. Genetic knockout of TRPV5 or TRPV6 in animals leads to phenotypes related to defective calcium homeostasis, including lowered serum calcium levels, decreased calcium absorption, reduced bone density, impaired sperm motility, and decreased maternal-fetal calcium transfer. In humans, aberrant TRPV5/6 expression is associated with preeclampsia and calcium nephrolithiasis (kidney stones). Additionally, TRPV6 expression level is upregulated in carcinomas of prostate, colon, breast, thyroid, and ovary, suggesting a role for TRPV6 in cancer survival. A detailed understanding of epithelial calcium entry is hindered by a lack of high-resolution structural information on intact channels. This dissertation presents structural analyses of the epithelial calcium channel TRPV6. We applied modern membrane protein screening and expression techniques, including fluorescence-detection size exclusion chromatography (FSEC) and baculovirus mediated mammalian cell transduction (BacMam), to identify optimal TRPV6 constructs and purification schemes for crystallization. Using a surface mutagenesis approach guided by lower-resolution structural solutions, we engineered a rat TRPV6 mutant (TRPV6cryst) that permitted solving a 3.25 Å resolution crystal structure. We used fluorescent calcium indicator assays to show that TRPV6cryst retains the permeation and ionic block properties of the wild type channel. The tetrameric structure of TRPV6cryst reveals a transmembrane domain architecture similar to voltage gated ion channels, with the ion conducting pore coincident with the overall four-fold symmetry axis. A ring of aspartate (D541) residues, shown in previous studies as a critical determinant of calcium selectivity, forms a narrow constriction at the extracellular pore entrance, or selectivity filter. Methionine (M577) side chains in the lower portion of the channel pore plug the conduction pathway and define the closed state of the channel. The ankyrin repeat domain, linker domain, N-terminal helix, and C-terminal hook form an intracellular skirt surrounding a cavity that lies beneath the pore axis. Close interactions between these domains, in large part mediated by the N-terminal helix, suggest that they are involved in allosteric modulation or concerted movements associated with channel activation. To shed light on the structural bases of permeation and ionic block, we cocrystallized TRPV6cryst with the permeant cations Ca²⁺ and Ba²⁺, and the channel blocker Gd³⁺. We identified binding sites for these cations by exploiting their anomalous scattering properties. On the basis of the cation-binding sites, we propose a permeation mechanism in which cations are recruited toward the pore by electronegative side chains in the extracellular vestibule, followed by sequential binding at least three binding sites along the central pore axis. Ca²⁺ selectivity is apparently achieved by high-affinity binding to the ring of D541 side chains in the selectivity filter. Gd³⁺ blocks permeation by similarly binding to the D541 ring and outcompeting ions of lesser charge. The results described in this dissertation provide a structural framework to further study mechanisms of epithelial calcium entry in health and disease.

Chan Ho Yu, Richard. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 115-122). / Abstracts in English and Chinese. / Declaration --- p.i / Acknowledgements --- p.ii / Abstract --- p.iii / 摘要 --- p.v / Table of Contents --- p.vii / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Potassium Channels --- p.1 / Chapter 1.1.1 --- Potassium Ions --- p.1 / Chapter 1.1.2 --- Potassium Channels --- p.1 / Chapter 1.1.3 --- Structure of K Channels --- p.2 / Chapter 1.1.4 --- Classification ofK Channels --- p.3 / Chapter 1.1.5 --- Mechanisms Contributed to K Channel Functions and Diversity --- p.5 / Chapter 1.1.5.1 --- RNA Editing --- p.5 / Chapter 1.1.5.2 --- Alternative Splicing --- p.6 / Chapter 1.1.5.3 --- Heteromultimeric Assembly of Principal Subunits --- p.6 / Chapter 1.1.5.4 --- Auxiliary Subunits --- p.7 / Chapter 1.1.5.5 --- Posttranslational Modifications --- p.7 / Chapter 1.2 --- Voltage-gated Potassium (Kv) Channels --- p.9 / Chapter 1.2.1 --- Diversity of Kv Channel Structure --- p.9 / Chapter 1.2.2 --- Early Origin of the Kv Family --- p.10 / Chapter 1.2.3 --- Structural Diversity of Kv Channels in Drosophila --- p.11 / Chapter 1.2.4 --- Structural Diversity of Kv Channels in Mammals --- p.11 / Chapter 1.2.5 --- Phylogenetic Tree of Kv Family --- p.13 / Chapter 1.2.6 --- Tissue Expression of Kv Channels --- p.13 / Chapter 1.2.7 --- "Three Main Functions of Kv Channels as Signaling Proteins: Ion Permeation, Gating and Sensing" --- p.16 / Chapter 1.2.7.1 --- Ion Permeation --- p.16 / Chapter 1.2.7.2 --- Gating --- p.18 / Chapter 1.2.7.2.1 --- Gating at the S6 Bundle Crossing --- p.18 / Chapter 1.2.7.2.2 --- Ball-and-Chain Gating --- p.19 / Chapter 1.2.7.2.3 --- Gating at the Selectivity Filter --- p.19 / Chapter 1.2.7.3 --- Sensing Mechanisms --- p.20 / Chapter 1.2.7.3.l --- Voltage Sensor --- p.20 / Chapter 1.2.7.3.2 --- Gating Sensors for Ligands --- p.21 / Chapter 1.3 --- KCNA10 --- p.22 / Chapter 1.3.1 --- "Rabbit Homologue of KCNA10, Kcnl" --- p.22 / Chapter 1.3.2 --- Genomic Localization of Human KCNA10 --- p.23 / Chapter 1.3.3 --- Human Gene for KCNA10 --- p.23 / Chapter 1.3.4 --- Basic Kinetic and Pharmacological Properties of KCNA10 --- p.25 / Chapter 1.3.5 --- "Regulation of KCNAlO by KCNA4B, a β -subunit" --- p.27 / Chapter 1.4 --- Aim of the Present Study --- p.30 / Chapter Chapter2: --- Materials and Methods --- p.31 / Chapter 2.1 --- Molecular Sub-Cloning ofKCNAlO --- p.31 / Chapter 2.1.1 --- Polymerase Chain Reaction (PCR) ofKCNA10 Fragment from KCNA Clone --- p.10 / Chapter 2.1.2 --- Separation and Purification of PCR Products --- p.32 / Chapter 2.1.2.1 --- Separation --- p.32 / Chapter 2.1.2.2 --- Purification --- p.33 / Chapter 2.1.3 --- Polishing the Purified PCR Products --- p.33 / Chapter 2.1.4 --- Ligation of PCR Products and pPCR-Script Amp SK(+) Cloning Vector --- p.34 / Chapter 2.1.5 --- Transformation --- p.34 / Chapter 2.1.6 --- Preparing Glycerol Stocks Containing the Bacterial Clones --- p.35 / Chapter 2.1.7 --- Plasmid DNA Preparation --- p.35 / Chapter 2.1.8 --- Clones Confirmation --- p.36 / Chapter 2.1.8.1 --- Restriction Enzyme Digestion --- p.36 / Chapter 2.1.8.2 --- Automatic Sequencing --- p.37 / Chapter 2.2 --- In situ Hybridization --- p.39 / Chapter 2.2.1 --- Probe Preparation --- p.39 / Chapter 2.2.1.1 --- Antisense KCNA10 RNA Probe --- p.39 / Chapter 2.2.1.2 --- Sense KCNA10 RNA Probe (Control Probe) --- p.40 / Chapter 2.2.2 --- Testing of DIG-Labeled RNA Probes --- p.43 / Chapter 2.2.3 --- Paraffin Sections Preparation --- p.43 / Chapter 2.2.4 --- In situ Hybridization: Pretreatment --- p.44 / Chapter 2.2.5 --- "Pre-hybridization, Hybridization and Post-hybridization" --- p.45 / Chapter 2.2.5.1 --- Pre-hybridization --- p.45 / Chapter 2.2.5.2 --- Hybridization --- p.45 / Chapter 2.2.5.3 --- Post-hybridization --- p.46 / Chapter 2.2.6 --- Colourimetnc Detection of Human KCNA10 --- p.46 / Chapter 2.3 --- Cell Culture --- p.47 / Chapter 2.3.1 --- Human Kidney Proximal Epithelial Cell Line (OK) --- p.47 / Chapter 2.3.2 --- Mouse Micro-vessel Endothelial Cell Line (H5V) --- p.48 / Chapter 2.3.3 --- Mouse Neuroblastoma Cell Line (NG108-15) --- p.48 / Chapter 2.3.4 --- Human Bladder Epithelial Cell Line (ECV304) --- p.48 / Chapter 2.3.5 --- Human T Cell Leukemia Cell Line (Jurkat) --- p.49 / Chapter 2.4 --- Total RNA Extraction --- p.49 / Chapter 2.5 --- Reverse Transcription from Cell Line --- p.51 / Chapter 2.6 --- Polymerase Chain Reaction (PCR) ofKCNAl 0 Fragment from Frist Strand cDNA --- p.51 / Chapter 2.7 --- Northern Hybridization --- p.52 / Chapter 2.7.1 --- Probe Preparation --- p.52 / Chapter 2.7.2 --- Separating RNA on an Agarose Gel --- p.52 / Chapter 2.7.3 --- RNA Transfer and Fixation --- p.52 / Chapter 2.7.4 --- Hybridization --- p.54 / Chapter 2.7.5 --- Post-hybridization --- p.54 / Chapter 2.7.6 --- Chemiluminescent Detection --- p.55 / Chapter 2.8 --- Intracellular Free Calcium Ion ([Ca2+］i) Measurement by Confocal Imaging System --- p.56 / Chapter 2.8.1 --- Bathing Solutions --- p.56 / Chapter 2.8.2 --- Preparation of Cells for [Ca2+]i Measurement --- p.56 / Chapter 2.8.3 --- Confocal Imaging System --- p.57 / Chapter 2.8.3.1 --- Fluo-3/AM Dye Loading --- p.57 / Chapter 2.8.3.2 --- [Ca2+]i Measurement --- p.57 / Chapter Chapter3: --- Results --- p.59 / Chapter 3.1 --- Phylogenetic Tree Reconstruction ofKCNAl0 --- p.59 / Chapter 3.2 --- Hydropathy Analysis ofKCNAl0 --- p.60 / Chapter 3.3 --- Molecular Sub-Cloning ofKCNAl0 --- p.61 / Chapter 3.3.1 --- Polymerase Chain Reaction (PCR) ofKCNAl0 Fragment from KCNA10 Clone --- p.61 / Chapter 3.3.2 --- Clones Confirmation --- p.63 / Chapter 3.4 --- In situ Hybridization Analysis ofKCNAl0 mRNAExpression --- p.65 / Chapter 3.4.1 --- Expression ofKCNAl0 in Human Kidney (Nephron) --- p.66 / Chapter 3.4.2 --- Expression ofKCNAl0 in Human Cerebral Artery --- p.69 / Chapter 3.4.3 --- Expression ofKCNAl0 in Human Cerebellum --- p.71 / Chapter 3.4.4 --- Expression ofKCNAl0 in Human Hippocampus --- p.73 / Chapter 3.4.5 --- Expression ofKCNAl0 in Human Occipital Cortex --- p.75 / Chapter 3.4.6 --- Expression ofKCNAl0 in Human Esophagus --- p.77 / Chapter 3.4.7 --- Expression ofKCNAl0 in Human Lung --- p.79 / Chapter 3.4.8 --- Expression ofKCNAl0 in Human Thyroid Glands --- p.81 / Chapter 3.4.9 --- Expression ofKCNAl0 in Human Adrenal Glands --- p.83 / Chapter 3.4.10 --- Expression ofKCNAl0 in Human Spleen --- p.86 / Chapter 3.5 --- RT-PCR ofKCNAl0 Fragment from Different Tissues --- p.88 / Chapter 3.6 --- Northern Blot Analysis of KCNA10 in Different Tissues --- p.90 / Chapter 3.7 --- Effects of Blocking KCNA10 on Ca2+ influx in Human Renal Proximal Tubule Epithelial Cells --- p.91 / Chapter Chapter4: --- Discussion --- p.97 / Chapter 4.1 --- Phylogency ofKCNAlO --- p.97 / Chapter 4.2 --- Hydropathy Plot for KCNA10 --- p.97 / Chapter 4.3 --- Expression ofKCNAl0 --- p.98 / Chapter 4.3.1 --- In situ Hybridization --- p.98 / Chapter 4.3.2 --- RT-PCR & Northern Blot Analysis --- p.99 / Chapter 4.4 --- Functional Implication of KCNA10 Expression in Different Human Tissues --- p.100 / Chapter 4.4.1 --- Unique Functional Properties ofKCNAlO --- p.100 / Chapter 4.4.2 --- Role ofKCNAlO in Renal Proximal Tubule --- p.101 / Chapter 4.4.2.1 --- Functions ofK+ Channels in Kidney --- p.101 / Chapter 4.4.2.2 --- The Function ofKCNAlO --- p.104 / Chapter 4.4.3 --- Role ofKCNAl0 in Blood Vessels --- p.106 / Chapter 4.4.3.1 --- Endothelial Cells --- p.106 / Chapter 4.4.3.2 --- Smooth Muscle Cells --- p.108 / Chapter 4.4.4 --- Role ofKCNA10 in CNS --- p.109 / Chapter 4.4.5 --- Role ofKCNAl0 in Secretory Cells --- p.111 / Chapter 4.4.6 --- Role ofKCNAl0 in Lung --- p.112 / Chapter 4.5 --- Conclusion --- p.114 / Chapter Chapter5： --- Reference --- p.115

Wong, Tak Hong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 96-104). / Abstracts in English and Chinese. / Thesis Committee --- p.i / Statement --- p.ii / Abstract --- p.iii / Chinese Abstract --- p.v / Acknowledgements --- p.vii / Abbreviation --- p.ix / Table of Content --- p.xi / List of figures --- p.xiv / List of tables --- p.xv / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Problem of soil salinization and sodification: reducing crop productivity --- p.1 / Chapter 1.2 --- Effects of high salinity on plant growth --- p.2 / Chapter 1.2.1 --- Ion toxicity --- p.2 / Chapter 1.2.2 --- Osmotic stress --- p.3 / Chapter 1.2.3 --- Oxidative stress --- p.3 / Chapter 1.3 --- Overview of salt tolerance mechanisms in plant --- p.4 / Chapter 1.3.1 --- Maintenance of ion homeostasis --- p.4 / Chapter 1.3.2 --- Maintaining osmotic homeostasis --- p.5 / Chapter 1.3.3 --- Detoxification of Reactive oxygen species --- p.5 / Chapter 1.4 --- The important role of CI- in plant salt stress tolerance research --- p.6 / Chapter 1.5 --- Introduction to chloride channel (CLC) family --- p.7 / Chapter 1.6 --- E. coli CLC-ecl: The first CLC member found to function as antiporter --- p.8 / Chapter 1.7 --- Yeast GEF1: eukaryotic model for early plant CLC complementation studies --- p.9 / Chapter 1.8 --- Mammalian CLC family: 4 channels and 5 antiporters --- p.10 / Chapter 1.8.1 --- CLC-4 and -5: First eukaryotic CLC member found to be function as antiporter --- p.13 / Chapter 1.8.2 --- CLC-7 function as antiporter and regulate lysosomal acidification --- p.13 / Chapter 1.8.3 --- "CLC-6 select nitrate over chloride, unlike other mammalian CLC members" --- p.14 / Chapter 1.9 --- Introduction to Plant CLC members --- p.14 / Chapter 1.10 --- Tobacco CLC-Ntl co-localized with mitochondrial markers in plant and may cause current on Xenopus oocytes membrane --- p.15 / Chapter 1.11 --- Rice CLCs may involved in salt tolerenace and growth regulation --- p.16 / Chapter 1.12 --- Arabidopsis CLC members are extensively studied --- p.18 / Chapter 1.12.1 --- AtCLCa regulates nitrate accumulation --- p.20 / Chapter 1.12.2 --- "AtCLCb, a nitrate/proton antiporter with unclear physiological role" --- p.22 / Chapter 1.12.3 --- "AtCLCc selective chloride over nitrate, involved in salt tolerance" --- p.23 / Chapter 1.12.4 --- AtCLCd and AtCLCf both localized on Golgi network --- p.25 / Chapter 1.12.5 --- AtCLCe may regulate ionic strength of chloroplast thylakoid membrane --- p.26 / Chapter 1.13 --- Previous work in Prof. Lam's laboratory --- p.26 / Chapter 1.14 --- "Reason, Hypothesis, Objective and long term significance" --- p.28 / Chapter 2. --- Materials and Methods --- p.30 / Chapter 2.1 --- Materials --- p.30 / Chapter 2.1.1 --- "Bacterial strains, animals, plants and plasmid vectors" --- p.30 / Chapter 2.1.2 --- Chemicals and Enzymes --- p.33 / Chapter 2.1.3 --- Commercial kits --- p.33 / Chapter 2.1.4 --- Primers --- p.35 / Chapter 2.1.5 --- Equipments and facilities used --- p.36 / Chapter 2.1.6 --- "Buffer, solution, gel and medium" --- p.36 / Chapter 2.1.7 --- Software --- p.36 / Chapter 2.2 --- Methods --- p.37 / Chapter 2.2.1 --- Growth and treatment of soybean seedling --- p.37 / Chapter 2.2.2 --- RNA extraction from root tissue --- p.37 / Chapter 2.2.3 --- RNA denaturing gel electrophoresis --- p.39 / Chapter 2.2.4 --- Generation and testing of single-stranded DIG-labeled PCR probes --- p.39 / Chapter 2.2.5 --- Northern blot analysis --- p.41 / Chapter 2.2.6 --- Transformation of V7/GmCLCl electro-competent Agrobacterium tumefaciens --- p.42 / Chapter 2.2.7 --- PCR screening of transformed Agrobacterium tumefaciens colonies --- p.43 / Chapter 2.2.8 --- DNA gel electrophoresis --- p.43 / Chapter 2.2.9 --- Agrobacterium-mediated transformation of tobacco BY-2 cells --- p.44 / Chapter 2.2.10 --- Verifying the expression of GmCLCl in transgenic tobacco BY-2 cells --- p.45 / Chapter 2.2.11 --- Salt treatment of tobacco BY-2 cells and cell viability assay --- p.46 / Chapter 2.2.12 --- Subcloning of GmCLCl cDNA into pgh21 vector --- p.47 / Chapter 2.2.13 --- In vitro synthesis of GmCLCl cRNA --- p.51 / Chapter 2.2.14 --- Obtaining oocyte from Xenopus laevis ovaries --- p.52 / Chapter 2.2.15 --- Microinjection of GmCLCl cRNA into Xenopus oocyte and oocyte incubation --- p.53 / Chapter 2.2.16 --- Two electrode voltage clamp of Xenopus oocytes --- p.54 / Chapter 3. --- Results --- p.56 / Chapter 3.1 --- Phylogenetic analysis of GmCLCl --- p.56 / Chapter 3.2 --- Expression of GmCLCl in root was induced by NaCl and alkaline condition --- p.60 / Chapter 3.3 --- Construction of GmCLCl transgenic tobacco BY-2 cell line --- p.62 / Chapter 3.4 --- GmCLCl improve NaCl stress tolerance of transgenic tobacco BY-2 cells in a pH dependent manner --- p.67 / Chapter 3.5 --- Subcloning of GmCLCl into pgh21 --- p.70 / Chapter 3.6 --- GmCLCl cRNA synthesis by in vitro transcription --- p.72 / Chapter 3.7 --- Two electrode voltage clamp (TEVC) of GmCLCl cRNA injected Xenopus oocytes --- p.75 / Chapter 4. --- Discussion --- p.81 / Chapter 4.1 --- Implications from phylogenetic and sequence analysis on the function of GmCLCl --- p.81 / Chapter 4.2 --- Electrophysiological characterization of GmCLC 1 by Xenopus oocytes --- p.82 / Chapter 4.3 --- Some plant CLCs contributed in salt tolerance response --- p.84 / Chapter 4.4 --- Relationship between pH and physiological function of plant CLCs --- p.85 / Chapter 5. --- Conclusion and Perspectives --- p.88 / Chapter 6. --- Appendices --- p.90 / Chapter Appendix I: --- Major Chemicals and reagents used in this research --- p.90 / Chapter Appendix II: --- Enzymes used in this research --- p.92 / Chapter Appendix III: --- Major equipment and facilities used in this research --- p.93 / Chapter Appendix IV: --- "Buffer, solution, gel and medium formulation" --- p.94 / Chapter 7. --- References --- p.96

A debilitating illness, pulmonary arterial hypertension (PAH) arises from deleterious remodeling of pulmonary arterioles, leading to increased pulmonary artery pressure, a rise in pulmonary vascular resistance, right sided heart failure and death. The pathogenesis of the disease is incompletely understood; however, certain established pathological features have guided medical treatments to improve mortality rates. For instance, an imbalance of vasoconstrictor molecules, such as endothelin-1, to vasodilator compounds, such as nitric oxide, contributes to excessive pulmonary arterial constriction, and a propensity for pulmonary arterial smooth muscle and endothelial cell proliferation. Therapeutic strategies may aim to restore this imbalance with the use of endothelin receptor antagonists, prostacyclin analogs, and other vasodilating agents. Mutations in the BMPR2 gene, the most common genetic cause of PAH, leads to aberrant TGF-ß signaling, which promotes uncontrollable cell proliferation and pathological changes in pulmonary arterioles. Genetic studies have revealed PAH-associated mutations in several other genes within the TGF-ß signaling pathway. More recently, our research group discovered loss-of-function mutations in the KCNK3 gene encoding the KCNK3 two-pore domain potassium channel in patients with idiopathic and familial PAH. KCNK3 (also referred to as TASK-1, or K2P3.1) represents the first ion channelopathy as a cause of PAH. KCNK3 is expressed in human pulmonary artery smooth muscle and endothelial cells. Loss of KCNK3 channel currents leads to membrane depolarization and predisposes to deleterious pulmonary arterial remodeling. Chapter 1 of my thesis explores the impact of KCNK3 mutations on potassium channel function in cellular models of heterozygous conditions, as all patients with PAH-associated KCNK3 mutations in our study were heterozygous at the KCNK3 gene locus. Furthermore, we explored function of mutant and non-mutant KCNK3 channels in cultured human pulmonary artery smooth muscle cells to better define the electrophysiological consequence of KCNK3 dysfunction, and used a KCNK3-activating pharmacological agent, ONO-RS-082, to gauge the therapeutic potential of KCNK3 as a pharmacological target in PAH. Moreover, the study of KCNK3 channel activity when assembled with the closely related KCNK9 channel provided a platform for exploring the lung-specific phenotype in patients with heterozygous KCNK3 mutations, despite widespread tissue expression KCNK3 in the body. In Chapter 2 of my thesis work, the discovery of a second potassium channelopathy in PAH is characterized. Heterozygous mutations in the ABCC8 gene, encoding the sulfonylurea receptor 1 (SUR1) protein, were found in pediatric and adult patients with idiopathic and familial PAH. SUR1, a beta subunit of the ATP-sensitive potassium channel (KATP), assembles with the pore-forming Kir6.2 alpha subunit to form KATP, a channel sensitive to inhibition by intracellular ATP. At the plasma membrane, KATP inwardly rectifying potassium currents contribute to the resting potential, and may play a pathophysiological role in PAH via dysfunction in pulmonary artery smooth muscle and/or endothelial cells. In this chapter, eight ABCC8 mutations associated with PAH were functionally characterized, and pharmacological agents were employed to examine the therapeutic potential in targeting SUR1-containing KATP channels in PAH. Altogether, the research presented in this dissertation identifies and explores potassium channel dysfunction as a pathogenic mechanism in PAH, due to heterozygous genetic mutations in KCNK3 and ABCC8. Evidence of restoration of mutant KCNK3 and KATP channel function by pharmacological agents suggests that targeting potassium channels as a therapeutic strategy may alleviate the severe morbidity and mortality burden in patients with PAH.

ClC proteins are chloride channels and transporters that are found in a wide variety of prokaryotic and eukaryotic cell-types. The mammalian chloride channel ClC-1 is an important modulator of the electrical excitability of skeletal muscle. The Torpedo electric-organ chloride channel, ClC-0 is structurally and functionally similar to ClC- 1. These proteins are referred to as the muscle-type ClC channels. The present work identifies several functional differences between the muscle type channels, and explores the structural basis of these and other previously reported differences. First the temperature dependence of ClC-1 channels was quantified. These calculations revealed distinct contrasts to previously published measurements of ClC-0 temperature sensitivity, indicating differences between the channels in the structural rearrangements associated with channel gating. Next the effect of extracellular ion substitution on ClC-0 function was examined. These measurements suggested that occupancy of an anion binding-site on the extracellular side of the selectivity-filter stabilises the open state of the channel, and that the diameter of the channel pore increases during channel opening. Three-dimensional models of the muscle-type channels were constructed based on the atomic coordinates of prokaryotic homologues. Differences in selectivity between ClC-0 and ClC-1 could be rationalised, in part, by differences in the chemistry of the narrow constriction of the channel pore. The major structural divergence between the muscle-type channels occurs in the expansive intracellular carboxy terminus. Replacing this region of ClC-1 with the corresponding region from ClC-0 resulted in distinct changes in common gating of the channel. These experiments rigorously characterise the dependence of ClC-1 function on temperature and the effect of foreign anionic-substrates on ClC-0 function. The results identify important residues involved in ionic selectivity of the channels, and validate the use of high-resolution prokaryotic channel structures as a predictive tool for studying the muscle-type channels. They also demonstrate that the carboxy-terminal of the channels is an important determinant of common gating. / Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2008

We present a serially concatenated coding scheme for partial response channels. The encoder consists of an outer irregular LDPC code and an inner matched spectrum trellis code. These codes are shown to offer considerable improvement over the i.i.d. capacity (> 1 dB) of the channel for low rates (approximately 0.1 bits per channel use). We also present a qualitative argument on the optimality of these codes for low rates. We also formulate a performance index for such codes to predict their performance for low rates. The results have been verified via simulations for the (1-D)/sqrt(2) and the (1-D+0.8D^2)/sqrt(2.64) channels. The structure of the encoding/decoding scheme is considerably simpler than the existing scheme to maximize the information rate of encoders over partial response channels.