No description available.

Our body is governed through a complex network of diverse set of synapses created by many different neurons, which extend throughout the body. A great progress has been made to monitor and modulate these cells using genetic methods in limited settings, while chemical approaches have not achieved comparable successful results. Yet given the versatility of chemical probes, it has been important to create platforms which would allow us to generate compounds with characteristics of neuronal targeting and modulation. In our effort to modulate neurons and their synapses, a platform of assays was developed to find agonists and modulators of the brain derived neurotrophic factor, BDNF, and its receptor, TrkB, which is a central signaling system for neurogenesis and synaptic plasticity. These assays were used to evaluate reported TrkB agonists and perform a high throughput screen. In addition, an alternative approach in the form of phage display targeting TrkB was employed, since TrkB proved to be a challenging target for identification of small molecule agonist or modulator. To visualize different parts as well as various types of neurons, two different platforms were developed. A diversity oriented fluorescent library coupled with high content screening provided an opportunity to identify probes that could specifically stain neurons and synapses. In the second approach a new phage display method was developed that could identify probes with the ability to bind to neuronal cell surface markers. The developed platforms that we developed have a great potential to generate promising probes for vast array of applications.

Conotoxins are peptides expressed by the exogenome of more than 800 species of marine mollusks belonging to the genus Conus (cone snails.) Owing to their high specificity and affinity for ion channels, transporter molecules, and cell receptors of the central and peripheral nervous systems, conotoxins have been investigated for nearly four decades. These efforts on conotoxin research made possible the FDA approved use of Ziconitide/Prialt, a conotoxin derived from the venom of Conus magus, which effectively treats patients suffering from severe chronic pain without consequent narcotic effects. Additionally, six other conotoxins have reached clinical trials and many novel ones are being discovered every day. Investigations reported in this dissertation broadens the applicability of conotoxins to non-excitable systems. Here, conotoxins from the dissected venom of the vermivorous cone snail Conus nux were isolated and purified by size exclusion and reverse phase HPLC and characterized by MALDI-TOF and MS/MS spectrometry. The purified conopeptide fractions revealed: 1) antagonist activity of conotoxin NuxVID on two human voltage-gated sodium channels, displaying capabilities as a practical molecular probe and a potential therapeutic lead. 2) Ability for two novel conotoxins to traverse artificial biological membranes, suggesting their potential as drug delivery systems. 3) In vitro capacity of several novel conopeptides to interfere with the adhesion of PfEMP1 domains, expressed in P. falciparum infected erythrocytes, to vascular endothelial and placenta receptors. Lastly, this work reveals binding of the synthetic form of α-conotoxin ImI, from the vermivorous cone snail Conus imperialis, to the α7 nAChR of macrophage-like-cells derived from the pre-monocytic leukemic cell line THP-1 in support of the involvement of this receptor in the cholinergic anti-inflammatory pathway. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Thesis (M. Ag.)--University of Adelaide, Depts. of Plant and Soil Sciences, 1995. / Includes bibliographical references (leaves 71-79).

Thesis (M.S.)--Duquesne University, 2004. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 87-94) and index.

Thesis (M.S.)--Biomedical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Bao, Gang; Committee Member: Merrill, Alfred; Committee Member: Santangelo, Philip. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph.D.) - University of St Andrews, May 2008. / Restricted until 13th May 2009.

No description available.

This doctoral thesis details a series of projects at the border of chemistry and neuroscience leading to the development of a novel family of probes which chemically target specific cells and molecules in the brain. Chapter 1 concisely introduces the history, development and applications of probes for monitoring brain activity and highlights synthetic voltage sensitive dyes as probes which have not yet reached their full potential, partly due to the lack of targeting strategies in brain tissue. Chapter 2 details the development of a new class of polymer-supported probes for ligand-directed delivery of fluorescent voltage sensitive dyes to monoaminergic neurons in live brain tissue. The polysaccharide dextran equipped with dichloropane as a ligand and either an electrochromic or PeT-based voltage sensor selectively targets dopaminergic and noradrenergic axons in mouse brain slice preparations. The new probes enabled voltage imaging in a defined neuronal population without the use of genetic manipulation. All following chapters describe modification of one of the components of the targeting platform developed in Chapter 2 aiming to optimize its performance or broaden its application potential. Chapter 3 extends the developed polymer platform to the targeting of a different molecular target – the AMPA-type glutamate receptor – via a ligand-directed covalent labeling strategy. Chapter 4 examines PEG as an alternative polymer carrier and shows that while dextran is more universal as a carrier, PEG provides superior targeting selectivity with negatively charged PeT-based voltage sensors. A series of targetable probes with improved voltage sensitivity based on the PEG platform is introduced here as well. Chapter 5 describes the synthesis of targetable probes carrying voltage sensors for imaging modalities other than visible light fluorescence, specifically for short wave infrared (SWIR) fluorescence and photoacoustic (PA) imaging. Chapter 6 shows the first steps towards adapting the delivery platform to the development of dual-ligand drugs for cell-selective pharmacology in the brain.

This thesis investigates the application of a variety of optical techniques for the manipulation of single cells and their local micro-environment. The methodologies developed provide enhanced control over a single cell under study affording exquisite spatial and temporal control over biological processes of interest. The work presented within the thesis can be split into three distinct categories. The first of these provides an investigation in light activated “caged” molecular probes. This work generated several new compounds which were then applied to providing control over processes involved in pain, mitochondrial intracellular signalling and memory processes in the central nervous system. Application of caged neurotransmitters then demonstrates the first in vitro wavelength orthogonal photolysis of biologically relevant substances. Such a technique has great potential in the study of fundamental interactions within the processes underpinning memory and cognitive function. Secondly the application of optical injection techniques for the introduction of membrane impermeable species of interest is presented. An exploration of laser sources and optical systems has yielded two new strategies for optical injection. The targeted introduction of fluorescent stains, nucleic acids and gold nanoparticles to the interior of live mammalian cells demonstrates the power of these techniques. Thirdly, an investigation in optical trapping and optical injection provides simplified micromanipulation techniqes for application to biological studies. The use of capillaries as reservoirs for reagents of interest has realised a procedure for the reduction of large-scale chemical assays to a single cell level in static flow. When this technique is combined with intelligent control over the trapping laser source’s temporal behaviour, the interaction with the sample under study can be tailored for biological amiability or sample ablation. In this way a single laser source can be employed for the optical trapping and nanosurgery of a biological sample. A final study is presented demonstrating initial results for the targeted optical injection of caged compounds into mammalian cells. This methodology draws on the strengths of optical injection and caging technologies and presents a significant step forward in the level of control afforded over a biological system under study by optical techniques. The studies presented highlight the level of control and flexibility afforded by the application of optical manipulation and excitation strategies. Such optical methodologies extend the photonic tools available for enhanced studies in the life sciences.