Master of Science, The Ohio State University, 2024, Animal Sciences

Extraintestinal pathogenic Escherichia coli (ExPEC) presents a substantial public health threat due to its ability to cause severe infections such as urinary tract infections, bloodstream infections, and meningitis. Recent evidence suggests that birds, particularly poultry, may serve as reservoirs for ExPEC strains pathogenic to humans. Avian pathogenic E. coli (APEC), the avian counterpart of ExPEC, causes multisystemic infections known as colibacillosis, resulting in high morbidity, mortality, and economic losses in poultry production. Current APEC control methods, relying on antibiotics and vaccines, face challenges due to rising multidrug resistance and vaccine failures against heterologous serotypes, highlighting the need for novel alternatives. In this study, we synthesized derivatives of a previously characterized piperazine-based quorum sensing inhibitor (QSI), QSI-5, through structural modifications preserving the piperazine core. This resulted in six derivatives, which were screened against APEC O78 using the autoinducer-2 indicator bacteria Vibrio harveyi BB170 to evaluate their efficacy in quorum sensing (QS) inhibition. Two derivatives such as 1-(naphthalen-2-ylmethyl)-4-(3-phenylpropyl)piperazine (OA4-108) and 1-((5-chlorobenzo[b]thiophen-3-yl)methyl)-4-(3-phenylpropyl)piperazine (OA4-109) exhibited enhanced activity at a 50 µM concentration, showing 100% inhibition in the screening assay. These two analogues also inhibited the bacterial motility and biofilm formation and displayed minimal to no toxicity on chicken and sheep red blood cells, chicken and human macrophage cells (HD-11, THP-1), and human intestinal epithelial cells (Caco-2). Additionally, they reduced the survival of APEC O78 in HD-11 and THP-1 cells. In vivo analysis using the wax moth model demonstrated the non-toxicity of these molecules, along with improved larval survival rates and reduced APEC load. Furthermore, OA4-108 and OA4-109 also showed quorum-sensing inhibition in multiple u (open full item for complete abstract)

Committee: Gireesh Rajashekara (Advisor); Timothy J Johnson (Committee Member); James R Fuchs (Committee Member) Subjects: Animal Sciences

Doctor of Philosophy, Case Western Reserve University, 2024, Genetics

Exportin-1 (XPO1) is an essential regulator of cellular nuclear export that traffics hundreds of cargo proteins from the nucleus into the cytoplasm. Nearly three decades of research led to a detailed understanding of the mechanisms underlying XPO1-mediated transport, and this knowledge generated many XPO1-targeting small molecule probes that validated the therapeutic potential of drugging nucleocytoplasmic trafficking. More recently, growing evidence has implicated XPO1 in other functions, including in the coordination of mitotic events, regulation of gene transcription, and formation of biomolecular condensates. These functions operate independently of nuclear export and implicate XPO1 as a broad regulator of many cellular functions. In this work, we demonstrate that many structural classes of electrophilic small molecules target XPO1 at cysteine 528 to suppress T cell activation. In contrast to known cytotoxic XPO1 modulators such as Leptomycin B and the FDA-approved Selinexor, we identify a new class of “Selective Inhibitors of Transcriptional Activation” (SITAs) that display potent inhibition of T cell function with minimal impacts on XPO1-mediated nuclear export, mitotic regulation, and cell viability. To assess how SITAs suppress T cell activation despite their muted effects on nuclear export, we provide evidence that XPO1 scaffolds transcription factors of the NF-κB, AP-1, and NFAT families during T cell activation. SITAs selectively disrupt XPO1 occupancy at euchromatic regions to indirectly abrogate the chromatin localization of NFAT, thereby suppressing T cell activation without affecting cell viability. Beyond the transcription factors that are critical for T cell function, we further demonstrate that the p300 histone acetyltransferase shares many chromatin occupancy sites with XPO1. Targeted modulation of XPO1 by SITAs or small molecule degraders indirectly suppresses p300 chromatin binding and activity, providing a potential mechanistic link between XPO (open full item for complete abstract)

Committee: Drew Adams (Advisor); George Dubyak (Committee Member); Anthony Wynshaw-Boris (Committee Member); Paul Tesar (Committee Chair) Subjects: Biology; Biomedical Research; Cellular Biology; Chemistry; Immunology; Molecular Biology; Organic Chemistry; Pharmacology

Master of Science, The Ohio State University, 2022, Comparative and Veterinary Medicine

Pseudomonas syringae pv. syringae (Pss) is an emerging seed-borne pathogen that causes Pseudomonas leaf spot (PLS) disease in bell peppers. It causes severe necrotic lesions on pepper leaves that can spread to 50-80% of the field under favorable environmental conditions. PLS can cause significant economic losses to pepper production if the disease is left uncontrolled. However, not much is known about the genes that Pss carries to be able to cause disease in peppers. It is important to understand the virulence genes that Pss carries so that appropriate measures can be developed to control Pss in peppers. Therefore, part of my research aimed to use comparative genomic analysis to understand the genes in Pss that are important for virulence in pepper seedlings. The Pss strains (n=16) evaluated showed varying levels of virulence (disease severity and Pss population) at 3-, 7-, and 14-days post-infection (dpi) on the susceptible 'California Wonder' pepper variety in a controlled growth chamber environment. The Pss strains also displayed varying growth, biofilm development, and motility in vitro in M9 minimal broth at 28˚C, however, the variation in in vitro performance did not explain the variation in the virulence of the Pss strains in pepper seedlings. Whole genome sequencing was performed on these Pss strains. The genes were functionally characterized, and core genomes were separated from the variable genomes between the Pss strains. A total of 812 genes were variable among the Pss strains including known virulence genes. Additionally, a multivariate correlation analysis identified 285 genes that were significantly correlated to the virulence of Pss in pepper seedlings (r2 of  0.5 to 0.675; P<0.01). The genes that were significantly correlated with the virulence of Pss strains included known virulence genes associated with motility (n=2), biofilm (n=5), and Type III and VI secretion systems (T3SS and T6SS) (n=9). Further, the two strains (SM156-18 and SM226-1) that (open full item for complete abstract)

Committee: Gireesh Rajashekara (Advisor); Sally Miller (Committee Member); James Fuchs (Committee Member) Subjects: Biology; Microbiology; Plant Pathology

Doctor of Philosophy, The Ohio State University, 2021, Chemistry

The purpose of this dissertation is to develop new synthetic routes built upon addressing green chemistry concepts such as energy efficient designs, use of renewable energy, use of renewable material, recyclable/reusability catalysts and develop biodegradable products. In this dissertation chapter 2, we describe the first report on complete aerobic oxidative dehydrogenation of any derivative of tetrahydroisoquinoline. This photocatalytic platform is achieved using off-the-shelf Ru(bpy)3Cl2 photosensitizer, sunlight, atmospheric oxygen/air and ambient temperature. The discovery of this new photocatalytic pathway was made possible through the combination theoretical calculations and droplet-based photoreaction screening platform that employs mass spectrometry for quantitative and qualitative monitoring of reaction intermediates and products in real-time. The optimized conditions were transferred to solution-phase isoquinoline synthesis, where 71.7% total yield could be produced in less than 4 h of reaction time using sun energy. Chapter 3 in this dissertation focusses on development of a new photocatalytic screening system based on catalytic oxygenation of small molecules using recyclable/reusable fullerene-C60. Here we developed a catalytic system for small molecules using interfacial reactivity of heterogeneous fullerene-C60 ¬catalyst – single component system. Fullerene-C60 is significant in photochemistry and is widely studied. In the work, we used characteristics of fullerene to develop a heterogeneous catalyst by binding the fullerene to a surface (e.g., thread or paper), which can be reused and/or recycled. Combination of this capability along with electrospray-based reaction screening enabled the discovery of easy, fast, green, and sustainable chemistry reaction processes such as photo-oxygenation and photo dehydro-dimerization. Chapter 4 features biodegradable Polylactide polymer catalytic synthesis from renewable material and the use of mass spectromet (open full item for complete abstract)

Committee: Abraham Badu-Tawiah (Advisor); Martin Haesemeyer (Committee Member); Anne Co (Committee Member); Vicki Wysocki (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2021, Comparative and Veterinary Medicine

Avian pathogenic E. coli (APEC), an extra-intestinal pathogenic E. coli (ExPEC), is one of the most common bacterial pathogens affecting poultry, including broilers, layers, breeders, turkeys and many other avian species. It causes high morbidity and mortality (up to 20%), decrease in production and increase in condemnation of carcasses (up to 43%) during slaughter, thus resulting in substantial economic losses to the poultry industry worldwide. Recent reports have suggested APEC as a source of human extra-intestinal infections, including urinary tract infections and sometimes meningitis. Further, APEC is also considered as a source of antibiotic resistance genes (ARGs) to human pathogens. Therefore, APEC is a pathogen of significant importance to both animal and human health. Currently, antibiotics are commonly used to control APEC infections; however, the increasing emergence of resistance to antibiotics and FDA (Food and Drug Administration) restrictions on using antibiotics in food-producing animals necessitate the development of new and effective antibacterials that can circumvent the resistance problem. Antibacterials targeting the outer membrane (OM) of bacteria can evade the problem of resistance in Gram-negative bacteria such as APEC. To this end, we discovered and evaluated small molecule (SM) growth inhibitors (GIs) and antimicrobial peptides (AMPs) affecting OM of APEC. We uncovered their antibacterial targets in the OM of APEC and assessed their impact on gut microbiome. We further demonstrated the potential of GIs as adjuvants to current antibiotics, including one of the last-resort antibiotics, colistin. A total of 11 GIs (GI1 – GI11) with bactericidal activity against APEC were identified through high throughput screening of pre-selected enriched small molecule library. Eight GIs that were effective and showed low toxicity in vitro in cultured epithelial and macrophage cells, red blood cells, and in vivo in wax moth (Galleria mellonella) larva mode (open full item for complete abstract)

Committee: Gireesh Rajashekara (Advisor); James Fuchs (Committee Member); Vlasova Anastasia (Committee Member); Hale Vanessa (Committee Member) Subjects: Animal Diseases; Bioinformatics; Microbiology; Molecular Biology; Molecules; Pharmaceuticals; Therapy

Doctor of Philosophy, Case Western Reserve University, 2020, Genetics

Loss of myelin-producing oligodendrocytes in the central nervous system (CNS) underlies several neurological diseases, including multiple sclerosis. Demyelinating disorders lead to cognitive and motor deficits, yet there are no FDA-approved remyelinating therapeutics. In the CNS, oligodendrocyte progenitor cells (OPCs) give rise to oligodendrocytes, which are capable of regenerating myelin. To discover novel therapies for demyelinating disorders, we performed in vitro chemical-genetic screens in OPCs looking for small molecules that enhance oligodendrocyte formation and remyelination. We found that the vast majority of pro-myelinating small molecules identified function, not through their canonical targets, but instead converge upon enzymes in the cholesterol biosynthesis pathway: CYP51, sterol-14-reductase, or EBP. Genetic experiments show that depletion of CYP51 or EBP enhances oligodendrocyte formation independent of small molecule treatment. Likewise, evaluation of in vivo validated remyelinating compounds, identified by other labs, confirmed that inhibition of CYP51, sterol-14-reductase, and EBP is a dominant mechanism shared by dozens of small molecules that enhance oligodendrocyte formation. The accumulation of the 8,9-unsaturated sterol substrates of CYP51, sterol-14- reductase, and EBP is a critical mechanistic node of these pro-myelinating compounds. Multiple molecules that enhance 8,9-unsaturated sterol intermediate levels can regenerate functional myelin in vivo and a human cortical spheroid model. Evaluation of 8,9-unsaturated sterol structural variants revealed that 24,25-epoxycholesterol also promotes oligodendrocyte formation, despite lacking an 8,9-unsaturation. 24,25-epoxycholesterol accumulates upon partial inhibition of LSS in the cholesterol biosynthesis pathway through the epoxycholesterol shunt. Therefore, our work establishes the epoxycholesterol shunt and 24,25- epoxycholesterol as another sterol signaling axis regulating OPC differentiatio (open full item for complete abstract)

Committee: Drew Adams Ph.D. (Advisor) Subjects: Biochemistry; Chemistry; Neurobiology; Pharmaceuticals

Doctor of Philosophy in Clinical-Bioanalytical Chemistry, Cleveland State University, 2018, College of Sciences and Health Professions

Hyaluronan (HA) is a large glycosaminoglycan (GAG) that is present in extracellular matrices (ECM) and it has a central regulatory role in inflammations. Many inflamed tissues are remarkably rich with deposited HA matrices, and increased HA has been associated with various inflammatory, angiogenic, fibrotic, and cancer promoting processes. In fact, modification of HA with additional ECM constituents can contribute to inflammation. HA binding proteins or hyaladherins are among the ECM constituents that play a key role in the inflammatory mechanism. Also, the physical characteristics of HA have an impact on inflammation. For example, edema is caused by fluid shifts in response to negatively charge HA accumulated at regions of damaged tissue. Moreover, HA polymers (mass length and distribution) are increasingly considered as a sensitive barometer of inflammation. Accordingly, swollen inflamed tissues are characterized by altered HA modification, in particular where it may be modified by covalently addition of the heavy chains (HC) of inter-alpha-trypsin inhibitor (IaI). This unique HC-HA matrix is highly adhesive for infiltrating immune cells and promotes inflammation at sites of tissue damage. The synthesis of HC-HA matrix is facilitated by a unique enzyme that is a product of tumor necrosis factor alpha-induced protein 6 (TNFa) also known as tumor necrosis factor-stimulated gene 6 (TSG-6) that is upregulated during inflammations. TSG-6 transfers HCs from IaI, a serum proteoglycan with 2 HCs on the bikunin chondroitin sulfate chain, onto HA to form the HC-HA matrix. The resulting HC-HA matrix extensively binds pro-inflammatory cells, which accumulate in inflamed tissues. In the case of inflammatory bowel diseases, recruitment of these cells to the intestinal submucosa occurs after formation of the HC-HA matrix, suggesting HC-HA is a key mediator of inflammatory disease progression. Therefore, we propose to identify ways to lower the levels of HC-HA crosslinking by in (open full item for complete abstract)

Committee: Vincent C. Hascall PhD (Committee Co-Chair); Aimin Zhou PhD (Committee Co-Chair); Carol de la Motte PhD (Committee Member); Mark A. Aronica MD (Committee Member); Yana I. Sandlers PhD (Committee Member); Xue-Long Sun PhD (Committee Member) Subjects: Biomedical Engineering; Biomedical Research

Doctor of Philosophy, The Ohio State University, 2018, Plant Pathology

Bacterial wilt of cucurbits is caused by the bacterium Erwinia tracheiphila (Et) and is considered one of the most destructive diseases of cucurbits in the Midwestern and Northeastern US, causing losses of up to 80%. Recent and early studies demonstrated a preference among Et strains to colonize hosts in the genus from which they were isolated. Non-productive (asymptomatic) colonization of non-preferred squash plants, and root colonization of both preferred and non-preferred hosts was demonstrated for the first time using a bioluminescent Et strain. Asymptomatic but colonized plants could serve as sources of inoculum in the field. Additionally, cucumber beetle larvae could acquire and transmit Et when feeding on roots, a phenomenon not previously considered in the epidemiology of this disease. Et is a pathogen undergoing relatively recent genomic changes, including a variable number of type VI secretion system (T6SS) gene clusters among Et strains. In single inoculations, BHKY, but not TedCu10 and MDCuke, was pathogenic to squash. Plants inoculated with either TedCu10 or MDCuke at 108 colony forming units (CFU)/ml followed immediately afterward by BHKY at 108 CFU/ml in the same sites remained asymptomatic. Single deletion mutants of the three T6SS loci in rifampicin-resistant MDCuke were generated via bi-parental mating. In vitro growth of MDCuke-Rif¿T6SS-2 was slightly higher than that of the wild type strain. The motility of MDCuke-Rif¿T6SS-1 on soft agar was significantly higher than that of the wild type strain. Single deletions did not affect the pathogenicity of MDCuke on melon plants or mediate the apparent competition between the preferred BHKY and non-preferred MDCuke strains in squash. Additional studies, including the generation and testing of double and triple deletion mutants of MDCuke T6SS loci and assessment of population size effects in intra-specific interactions are needed to unravel the mechanisms leading to the disease suppression phenotype obser (open full item for complete abstract)

Committee: Sally Miller PhD (Advisor) Subjects: Plant Pathology

Doctor of Philosophy, The Ohio State University, 2018, Plant Pathology

Salmonellosis cases caused by Salmonella enterica through pre-harvest contamination of fresh produce represent a risk to human health worldwide; however, little is known about the interactions between Salmonella, phytopathogens, environment, and the plant host contributing to this food safety issue. Furthermore, the control of Salmonella from “farm to fork” is challenging due to the development of resistance mechanisms towards current control methods and restrictions on use of antimicrobials imposed by regulatory agencies. We investigated the effects of specific environmental conditions on the persistence and dissemination of Salmonella enterica subsp. enterica serotype Typhimurium (S. Typhimurium) following artificial contamination of `Tiny Tim' tomato plants. We found that higher temperatures (30°C day/25°C night) reduced the persistence of S. Typhimurium in the phyllosphere compared to lower temperatures (20°C day/15°C night) when plants were sprayed on the leaves with a S. Typhimurium -contaminated solution. Wounding cotyledons with contaminated tools increased S. Typhimurium persistence and internalization in planta compared to spray inoculation. Low relative humidity enhanced the dissemination of Salmonella into non-inoculated plant tissues. S. Typhimurium was detected in the root systems for at least 98 days-post inoculation. Further, we showed that splice-grafting (`Celebrity' with 'MaxiFort') is a major risk for the internalization and long-term survival of S. Typhimurium inside the tomato plant. S. Typhimurium was detected in the root system for over 137 days if at least 5 x 10^3 colony-forming units were introduced during grafting. The survival of S. Typhimurium in tomato foliage was also affected by the presence of phytopathogens, the genotype of S. Typhimurium and tomato variety used. We found that rfbV, involved in O antigen synthesis, might be essential for S. Typhimurium persistence in inoculated tomato plants and especially in `Tiny Tim' plants (open full item for complete abstract)

Committee: Gireesh Rajashekara (Advisor); Sally Miller (Advisor); Laurence Madden (Committee Member); Christopher Taylor (Committee Member); Corey Nislow (Committee Member) Subjects: Agriculture; Bioinformatics; Biology; Environmental Health; Molecular Biology; Plant Pathology; Public Health

Master of Science, The Ohio State University, 2017, Comparative and Veterinary Medicine

Avian Pathogenic E. coli (APEC), an extraintestinal pathogenic E. coli (ExPEC), is one of the most common bacterial pathogens affecting chickens, turkeys, and other avian species. It causes multiple extra-intestinal infections which subsequently lead to high morbidity and mortality, production losses, and increased slaughter condemnation resulting severe economic loss to the global poultry industry. Antimicrobial medication is the major approach currently employed to reduce the incidence and mortality associated with this infection. However, multi-drug resistant (MDR) APEC strains are reported nowadays worldwide. Furthermore, vaccination which is used as a subsidiary approach to prevent infection frequency is not sufficient to provide protection against diverse heterologous APEC serotypes. Therefore, the objective of this study is to identify novel small molecule (SM) growth inhibitors of APEC and to evaluate toxicity and efficacy of identified SMs, in vitro and in vivo. Here, using a Tecan Sunrise™ absorbance plate reader, a pre-selected enriched SM library containing 4,182 SMs was screened at 100 µM concentration against a predominant field APEC serotype, APEC O78, grown in minimal M63 media. Of the total 4,182 SMs, 41 SMs inhibited APEC O78 growth. The majority of growth inhibitory SMs were found belonging to chemical groups; quinolines, piperidines, pyrrolidinyls, and imidazoles. Among 41 SMs, 30 SMs exhibited bacteriostatic activity, while remaining 11 SMs displayed bactericidal activity and were selected for further studies. Dose-response analysis of these selected SMs revealed their dose-dependent activity with minimal inhibitory concentration (MIC) ranging 12.5 µM to 200 µM. These selected SMs were found broadly effective against various APEC serotypes such as O1, O2, O8, O15, O18, O35, O109, and O115. Six of these SMs exhibited narrow-spectral activity affecting 1-3 tested commensal bacteria. Except SM11, other SMs were least toxic to Caco-2 epithelial (< (open full item for complete abstract)

Committee: Gireesh Rajashekara (Advisor); Chang-Won Lee (Committee Member); Anastasia Vlasova (Committee Member) Subjects: Animal Diseases; Microbiology; Therapy; Veterinary Services

Master of Science, The Ohio State University, 2016, Chemistry

Hydrogenase (H2ases) enzymes carry out bidirectional hydrogen production and oxidation reactions. To better understand the mechanism of hydrogen conversion, spectroscopic studies on small molecule mimics provide important metrics to correlate structure and function of the native enzymes. In this work, a series of molecular complexes that mimic the [NiFe] hydrogenase have been synthesized with different phosphine ligand substituents and analyzed using multiple analytical techniques, including nuclear magnetic resonance, Fourier transform infrared, and resonance Raman spectroscopies. Three model compounds have been selected as the focus of this investigation into the vibrational structure of the [NiFe] active site: [Ni(dppe)(µ-pdt)(µ-H)Fe(CO)3][BF4], [Ni(dcpe)(µ-pdt)(µ-H)Fe(CO)3][BF4], and [Ni(dppbz)(µ-pdt)(µ-H)Fe(CO)3][BF4]. (dppe= diphenylphosphinoethane, dcpe= dicyclohexylphosphinoethane, and dppbz= diphenylphosphinobenzene). These compounds have been previously synthesized and shown to exhibit high activity for proton reduction but have not been fully characterized spectroscopically to assess the solution-phase structure of the metal-hydride core. (Barton et al., 2010, JACS. 132, 14877-14885.) Specifically, resonance Raman (RR) spectroscopy was used to study the vibrational bands of each of the molecules, which were then assigned to specific normal modes of the molecule. The [Ni(dppe)(µ-pdt)(µ-H)Fe(CO)3]BF4 compound has been previously studied in great detail by RR, and this molecule was used as a template from which to understand the structures of the series. It was found that perturbations of ligands on the metal center alter the molecular vibrations, particularly of the metal-hydride core. This work provides important metrics for comparison between synthetic and the natural enzyme systems, with the intention of better understanding the mechanisms of native hydrogenases and informing next-generation catalyst design.

Committee: Hannah Shafaat Dr. (Advisor); Nagib David Dr. (Committee Member) Subjects: Chemistry

Doctor of Philosophy, University of Akron, 2016, Polymer Science

The emergence of giant molecules built up from molecular nanoparticles (MNP) based nanoatoms has attracted substantial attentions because of their unique molecular design with shape and interaction anisotropy as well as conformation rigidity, leading to intriguing self-assembly behaviors different from traditional building blocks. Numerous hierarchically assembled structures deriving from giant molecules have been theoretically predicted by computer simulation. However, experimental exploration is still in the infancy. In this dissertation, we are aiming to develop several categories of giant molecules based on precisely functionalized fullerene (C60), and study their versatile self-assembly behaviors. To break symmetry, hydrophilic C60-based nanoatoms are designed, bearing multiple carboxyl acid (AC60) or hydroxyl groups (DC60). They are hexa-adducts of C60 with precisely defined chemical structures, synthesized by Bingel reaction. Various giant molecules can be achieved through attaching different hydrophobic building blocks onto these hydrophilic C60 via “click” chemistry. First of all, two molecular Janus particles with different molecular architectures were obtained by tethering an AC60 with one (AC60-C60) or two (AC60-2C60) hydrophobic C60. Investigation on the solution self-assembly behavior of these two molecular Janus particles reveals that molecular architectures and solvent polarity are critical parameters in determining the assembled structures. Moreover, the conjugation of AC60 with a cyclic polystyrene (CPS) using sequential click approaches gave rise to a set of novel giant molecules, which are referred to as “nano-diamond-ring-like” giant surfactants. They possess particular molecular structures, and may exhibit completely different self-assembly behaviors from the traditional self-assembly building blocks. We then extend such studies on the assembly of giant molecules in condensed state by synthesizing giant molecules composed of one AC60 tethere (open full item for complete abstract)

Committee: Stephen Cheng (Advisor); Toshikazu Miyoshi (Committee Chair); Tianbo Liu (Committee Member); Abraham Joy (Committee Member); Chrys Wesdemiotis (Committee Member) Subjects: Chemistry; Materials Science; Polymer Chemistry; Polymers

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2015, Photochemical Sciences

A molecular level understanding of photodynamics in condensed media is one of the recent challenges to chemical physics. This is because of the intrinsic complexity of liquid-phase photophysical and photochemical singularities arising from competing intra- and intermolecular processes. Such processes often take place on a timescale of a few femtoseconds (10-15 s) to several tens of picoseconds (10-12 s). In this work, the model photochemical processes used to investigate ultrafast photo-induced reaction dynamics in solution. The model compounds are non-metal/metal polyhalogenated small molecules. The gas-phase photochemistry of these small molecules is thoroughly examined, which also enables to establish the connection between liquid and gas phase dynamics. Furthermore, contrary to the scrupulously investigated di- and triatomic molecular systems, more vibrational degrees of freedom are accessible both for the model parent molecules, nascent polyatomic radical species, and isomer photoproducts. Therefore, a detailed mapping of the photochemical reaction paths of these molecular systems can possibly reveal different couplings between the reactive modes and other dark states in a far-from-equilibrium situation. The complexity of the encountered ultrafast events requires the utilization of several experimental and computational approaches. Results of femtosecond transient absorption, picosecond transient resonance Raman, excited state ab initio calculations are discussed in this context.

Committee: Alexander Tarnovsky Dr. (Advisor); Haowen Xi Dr. (Other); Marshall Wilson Dr. (Committee Chair); Alexey Zayak Dr. (Committee Chair) Subjects: Chemistry; Physical Chemistry

Doctor of Philosophy, The Ohio State University, 2009, Veterinary Biosciences

Prostate cancer is the most commonly diagnosed noncutaneous cancer and the second leading cause of cancer death in men. To combat the assortment of genomic and cellular aberrations that occur with the progression of this disease, we have developed novel classes of histone deacetylase (HDAC) inhibitors, 3-phosphoinositide dependent protein kinase-1 (PDK1)/Akt inhibitors, and indole-3-carbinol analogs using phenylbutyrate, celecoxib, and indole-3-carbinol, respectively, as scaffolds. Here, we assess both the efficacy and safety of the lead compounds of these classes (OSU-HDAC42, OSU-03012, and OSU-A9) administered orally in a series of preclinical studies carried out, in part, in preparation for prevention and regression trials in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model. Following the acquisition of relevant in vitro and dose-ranging data, the tumor-suppressive efficacy of selected doses was evaluated in PC-3 xenograft ± TRAMP-C2 syngeneic mouse models. The oral drug formulation found to achieve the most promising benefit-risk ratio was incorporated into a diet and administered to TRAMP mice for the assessment of its morphologic and molecular effects on the development of prostatic intraepithelial neoplasia (PIN) and carcinoma. Toxicity was evaluated by histopathologic, hematologic, and body and organ weight analysis. OSU-HDAC42 achieved the most potent blockade of prostate tumorigenesis reported in the TRAMP model, suppressing the absolute and relative weights of the urogenital tracts by 86% and 85%, respectively, in association with intraprostatic modulation of biomarkers indicative of HDAC inhibition, increased apoptosis and differentiation, and decreased proliferation. This compound, while sparing body weight, caused reversible testicular degeneration and hematologic alterations. In addition to its prostate chemopreventive effects, OSU-03012 was found to induce the hepatic biotransformation enzymatic system and caused phenotypic changes p (open full item for complete abstract)

Committee: Ching-Shih Chen PhD (Advisor); Robert Brueggemeier PhD (Committee Member); Steven Clinton MD, PhD (Committee Member); Thomas Rosol DVM, PhD (Committee Member) Subjects: Animals; Biochemistry; Health Care; Molecules; Oncology; Pathology; Pharmaceuticals; Pharmacology; Therapy; Toxicology; Veterinary Services

Doctor of Philosophy (PhD), Ohio University, 2007, Molecular and Cellular Biology (Arts and Sciences)

Bacillus subtilis tyrS is an aminoacyl-tRNA synthetase gene that is a member of the T box family of genes, which are found in many Gram-positive bacteria. This family includes aminoacyl-tRNA synthetase, amino acid biosynthetic and amino acid transport genes, and these genes are characterized by a highly-conserved sequence of nucleotides known as the T box sequence. Expression of these genes is regulated by the interaction of uncharged cognate tRNA with the 5' untranslated region of the nascent mRNA. One feature of this interaction is the base pairing of the tRNA acceptor end with four bases of the antiterminator, a conserved mRNA structural element that contains a seven-nucleotide bulge flanked by two helices. The tRNA-antiterminator base pairing prevents the formation of an alternative terminator element and results in complete transcription of the gene. This research investigates binding of tRNA and small molecules to the T box antiterminator using two antiterminator models, AM1A and AM1A(C11U) which represent the wild type aniterminator and a reduced function variant, respectively. From chemo-enzymatic probing and fluorescence studies data, the structural changes occurring in AM1A upon the binding of the acceptor end tRNA to only the first four nucleotides of the bulge and the greater flexibility of AM1A(C11U) compared to AM1A indicate that binding of tRNA occurs via tertiary structure capture and induced fit. Native gel mobility shift, fluorescence studies, and nucleotide analog interference mapping (NAIM) indicated that the integrity of the A2 helix and Mg2+ concentration play an important role in binding of tRNA to antiterminator. The functional groups probed by NAIM of absolutely conserved A10 (A223 of B. subtilis tyrS) were not essential for the binding of tRNA, but the presence of a methyl group on the amino functionality of A10 may sterically hinder binding. Using fluorescence resonance energy transfer and enzymatic probing, neomycin B and two oxazolidinon (open full item for complete abstract)

Committee: Jennifer Hines (Advisor) Subjects:

PHD, Kent State University, 2008, College of Arts and Sciences / School of Biomedical Sciences

Prophylactic and therapeutic antiviral drugs for influenza are available as an adjunct to vaccination. However, their effectiveness is already being limited because of the rapid emergence of drug resistant isolates due to the vast use of these drugs and the recombination potential of the viral genome. Moreover, an immediate pandemic threat (influenza H5N1) raises issues like the lack of surge capacity and availability of drugs as well as potential drug resistance. Given the need for additional antiviral agents, our study intended to identify new compounds with potential anti-influenza activity. This was done by screening a library of 34,000 small molecules by means of a cell-based system that assayed the inhibition of virus-induced cell death. As a result, 330 primary hits were identified from which two lead compounds (QMV-13 and QMV-15) and three of their analogs (QMV-13B, QMV-15A, QMV-15B) were described as potential candidates for further characterization. First, we evaluated their cytotoxicity in a variety of primary and immortalized cell lines. Next, their antiviral activity against influenza A/WSN/33 was confirmed using different methods. Furthermore, replication of a cohort of influenza A and B laboratory-adapted, clinical isolates, and drug resistant strains was quantified in the presence of the leads, resulting in low IC50 values. Next, we tested the specificity of their antiviral activity against other RNA viruses such as YFV, WNV, hPIV3, and HIV, eliminating the possibility of a broad spectrum of action. Time-of-drug-addition assays, viral protein expression, and virus growth kinetics experiments characterized our compounds as early inhibitors of virus replication. The lack of inhibitory response against virus neuraminidases helped eliminating that enzyme as their target. Finally, serial passages of the virus in the presence of the lead compounds were done to generate drug resistant variants that could pinpoint more accurately their target. Although th (open full item for complete abstract)

Committee: Miguel E. Quinones-Mateu PhD (Committee Chair); Robert T. Heath PhD (Committee Member); Philip E. Pellett PhD (Committee Member); Oscar Rocha PhD (Committee Member); Kenneth S. Rosenthal PhD (Committee Member); Christopher J. Woolverton PhD (Committee Member) Subjects: Biomedical Research; Cellular Biology; Molecular Biology; Virology

Doctor of Philosophy (Ph.D.), University of Dayton, 2011, Biology

1: Silver nanoparticles (Ag Np's) have an interesting surface chemistry and unique plasmonic properties. They are used in a wide variety of applications ranging from consumer products like socks, medical dressing, computer chips and it is also shown to have antimicrobial, anti bacterial activity and wound healing. Ag Np toxicity studies have been limited to date which needs to be critically addressed due to its wide applications. Mouse embryonic stem (MES) cells represent a unique cell population with the ability to undergo both self renewal and differentiation. They exhibit very stringent and tightly regulated mechanisms to circumvent DNA damage and stress response. We used 10 nm coated (polysaccharide) and uncoated Ag Np's to test its toxic effects on MES cells. MES cells and embryoid bodies (EB's) were treated with two concentrations of Ag Np's: 5 µg/ml and 50 ug/ml and exposed for 24, 48 and 72 hours. Increased cell death, ROS production and loss of mitochondrial membrane potential and alkaline phosphatase (AP) occur in a time and a concentration dependant manner. Due to increased cell death, there is a progressive increase in Annexin V (apoptosis) and Propidium Iodide (PI) staining (necrosis). Oct4 and Nanog undergo ubiquitination and dephosphorylation post-translational modifications in MES cells thereby altering gene expression of pluripotency factors and differentiation of EB's into all the three embryonic germ layers with specific growth factors were also inhibited after Ag Np exposure. Flow cytometry analysis revealed Ag Np's treated cells had altered cell cycle phases correlating with altered self renewal capacity. Our results suggest that Ag Np's effect MES cell self renewal, pluripotency and differentiation and serves as a perfect model system for studying toxicity induced by engineered Ag Np's. ABSTRACT 2: The reprogramming of fibroblasts to pluripotent stem cells and the direct conversion of fibroblasts to functional neurons has been successfully man (open full item for complete abstract)

Committee: Hong Yiling (Advisor); Shirley J. Wright (Committee Member); Mark G. Nielsen (Committee Member); Tsonis A. Panagiotis (Committee Member); Shawn M. Swavey (Committee Member) Subjects: Biology

Doctor of Philosophy, Case Western Reserve University, 1993, Chemistry

The major objectives of this thesis research are two fold: (1) to study the mechanisms of the electrocatalytic oxidation of methane, ethane and ethylene and (2) to understand the factors controlling the kinetics of these processes. An understanding of the mechanisms of the electrocatalytic oxidation of these hydrocarbon molecules has been reached by identifying the adsorbed species, intermediates as well as products which are either adsorbed on the electrode surface or dissolved in the electrolyte. Two types of adsorbed species have been identified by means of electrochemical, in situ FTIR and ex situ NMR techniques. Type I species are linearly bonded carbon monoxide (CO L), which can be formed on platinum electrode surfaces from the adsorption of any of the three hydrocarbon molecules investigated in this thesis work. Type II species are alcohol-like (most probably ethylene glycol), which are expected to be formed from the adsorption of C2 molecules (e.g., ethane and ethylene). Carbon monoxide has been considered as a reaction intermediate rather than just a "blocking agent" for the electrochemical oxidation of small hydrocarbon molecules. The alcohol-like type II species adsorbed on the platinum surface with higher bonding strength are expected to be the possible blocking species for the ele ctrocatalytic oxidation of small hydrocarbon molecules with two or more carbon atoms at lower temperatures. On the basis of the electrochemical and spectroscopic investigations, the possible reaction paths have been proposed by the author. At elevated temperatures, the rate-determining step in the oxidation of these hydrocarbons has been considered to be the reaction between adsorbed carbon monoxide and water, which is represented as the following: COad + H2Oad→ COOHad + H+ + e-. The temperature effect on the formation and oxidative desorption of the two types of species on platinum has been investigated from room temperature to 180°C. At elevated temperatures (>150°C), the ox (open full item for complete abstract)

Committee: Ernest Yeager (Advisor) Subjects: Chemistry, Physical

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2010, Photochemical Sciences

A detailed understanding of condensed-phase ultrafast photo-induced chemical reaction dynamics is still sought after. This is because of the intrinsic complexity of liquid-phase photophysical and photochemical phenomena arising from competing intra- and intermolecular processes. Such processes often take place on a timescale of a few femtoseconds to several tens of picoseconds. In this work, the model photochemical processes used to investigate ultrafast photo-induced reaction dynamics in solution are bond-breaking and bond making reactions. The model compounds are di- and poly-halogenated methanes. The gas-phase photochemistry of these small molecules is thoroughly investigated, which enables to draw a direct comparison to the photophysical and photochemical dynamics in solution. Moreover, in contrast to the thoroughly investigated di- and triatomic molecular systems, more vibrational degrees of freedom are available both to the model parent molecules and nascent polyatomic radical species. Thus, a detailed mapping of the photochemical reaction paths of these systems develops into a comparative advantage, revealing different couplings between the reactive modes and other dark states in a far-from-equilibrium situation. The complexity of the encountered ultrafast phenomena requires the use of several experimental and computational approaches. Results of femtosecond transient absorption, picosecond transient resonance Raman, and matrix isolation experiments in concert with ground and excited state ab initio calculations are discussed in this context. The findings from this work illustrate the power of a solvent environment in (i) altering the topology of ground and excited state potential energy surfaces, and (ii) leading to different photoproducts through intermediates otherwise absent from gas-phase studies.

Committee: Alexander Tarnovsky PhD (Committee Chair); Massimo Olivucci PhD (Committee Co-Chair); R. Marshall Wilson PhD (Committee Member); H. Peter Lu PhD (Committee Member); Rex Lowe PhD (Other) Subjects: Chemistry