ClC proteins encompass a large protein family consisting of both voltage-dependent chloride channels and chloride/proton exchangers that are found in both eukaryotes and prokaryotes. These proteins mediate Cl- flux across the plasma membrane or intracellular membranes of many cell types including neurons, epithelial cells, and skeletal muscle in mammals. Mutations in genes encoding these channels also contribute to several human diseases. The mechanism of ion conduction through ClC proteins is becoming better defined, largely due to the availability of a crystal structure of a bacterial ClC transporter. Because crystal structures only capture a snapshot a protein in a single conformation, however, the large conformational changes associated with channel opening and closing have remained largely undefined. In the cation channel field, ion conduction and conformational changes that occur during channel gating have been studied using peptide toxin inhibitors isolated from animal venoms. However, only one peptide toxin inhibitor of a chloride channel of known molecular identity has ever been identified. Georgia anion toxin 1 (GaTx1), inhibits the CFTR chloride channel, which is unrelated to ClC proteins on the levels of both three dimensional structure and primary sequence. Here, we describe the characterization of the inhibitory activity of Leiurus quinquestriatus hebraeus scorpion venom against the ClC-2 chloride channel. We found that the venom from this scorpion contains a peptide component that is capable of inhibiting the ClC-2 chloride channel. This component was isolated using standard chromatography techniques, and found that the active component is a 3.2 kDa peptide composed of 29 amino acids. We showed that the active toxin, Georgia anion toxin 2 (GaTx2), interacts with ClC-2 with an affinity in the picomolar range, and appears to slow channel opening. Finally, GaTx2 is not capable of inhibiting other members of the ClC protein family, other major chloride channels, or voltage-gated potassium channels. This toxin will provide a new tool for structure/function studies of ClC-2, and will hopefully serve as only the first toxin inhibitor available for this protein family.

Botulinum toxin (BTX) is used in various fields of medicine, including the treatment of hyperhidrosis and cervical dystonia. Botox®, Dysport®, Xeomin® and NeuroBloc® are commercially available BTX products, which are formulated differently and their dosing units are unique. Dosage and concentration of the prepared solution for injection varies considerably among studies comparing the products. Improved guidelines on concentration and dosing when changing from one product to another are warranted. This would ensure the use of the lowest effective doses for good effect, minimal risk of antibody formation and side-effects as well as reduced costs. The aim of the present work was to find the most appropriate BTX concentration for each of the four products to achieve the highest sweat reducing effect and to investigate dose conversion ratios between Botox and Dysport in the treatment of cervical dystonia when the products are diluted to the same concentration, 100 U/ml. Paper I and II clearly confirm that it is crucial to consider the BTX concentration in a treatment regimen, especially when changing between different products. The optimal concentration to reduce sweating varies among the products and was found to be 25 U/ml for Botox and Xeomin, approximately 100 U/ml for Dysport and 50 U/ml for NeuroBloc. However, for NeuroBloc the optimal concentration might be even lower. In Paper III, which is a retrospective study using casebook notes from 75 patients with cervical dystonia, it was found that the most appropriate dose conversion ratio to use when switching from Botox to Dysport was 1:1.7. In Paper IV, Botox and Dysport were prospectively compared in a double-blind, randomized clinical trial in two different dose conversion ratios (1:3 and 1:1.7) when diluted to the same concentration (100 U/ml). No statistically significant difference was seen between Botox (1:3) and Dysport nor between Botox (1:1.7) and Dysport four weeks after treatment. Some of the secondary outcome observations, however, did indicate that the ratio 1:3 resulted in suboptimal efficacy of Botox but this must be further validated in a larger patient material.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 175-194).

Thesis (M.S.)--Brigham Young University. Dept of Physiology and Developmental Biology, 2007. / Includes bibliographical references (p. 41-44).

Regensburg, Univ., Diss., 2009.

München, Techn. Univ., Diss., 2004. / Enth. 2 Sonderabdr. aus: The Journal of Biological Chemistry ; 41. 2003 und: The Journal of Clinical Investigation ; 10. 2004

Universiẗat, Diss., 2002--Essen.

Techn. Hochsch., Diss., 2002--Aachen.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 151-169).

abstract: In the United States, Escherichia coli O157:H7 (E. coli O157:H7) is the most frequent cause of hemolytic uremic syndrome (HUS) and it is also the primary cause of acute renal failure in children. The most common route of the infection is ingestion of contaminated meat or dairy product originating from cattle or vegetables contaminated with bovine manure. Since cattle are the main reservoir for human infection with E. coli O157:H7, the reduction of intestinal colonization by these bacteria in cattle is the best approach to prevent human infections. Intimin is an outer membrane protein of E. coli O157:H7 that plays an important role in adhesion of the bacteria to the host cell. Hence, I proposed to express intimin protein in tomato plants to use it as a vaccine candidate to reduce or prevent intestinal colonization of cattle with E. coli O157:H7. I expressed His-tagged intimin protein in tomato plants and tested the purified plant-derived intimin as a vaccine candidate in animal trials. I demonstrated that mice immunized intranasally with purified tomato-derived intimin produced intimin-specific serum IgG1and IgG2a, as well as mucosal IgA. I further demonstrated that mice immunized with intimin significantly reduced time of the E. coli O157:H7 shedding in their feces after the challenge with these bacteria, as compared to unimmunized mice. Shiga toxin is the major virulence factor that contributes to HUS. Since Shiga toxin B subunit has an important role in the attachment of the toxin to its receptor, I fused intimin to Shiga toxin B subunit to create multivalent subunit vaccine and tested the effects upon immunization of mice with the B subunit when combined with intimin. His-tagged intimin, Shiga toxin B subunit, and Shiga toxin-intimin fusion proteins were expressed in E. coli and purified. I demonstrated that this multivalent fusion protein vaccine candidate elicited intimin- and Shiga toxin B-specific IgG1, IgG2a, and IgA antibodies in mice. I also showed a reduction in the duration of the bacterial shedding after the challenge compared to the control sham-immunized groups. / Dissertation/Thesis / Ph.D. Plant Biology 2010