Chemicals and Drugs Commons^™

Characterizing And Overcoming Resistance To Aminomethylspectinomycins In Gram-Negative Bacteria, Nisha Das

Theses and Dissertations (ETD)

Spectinomycin (SPC) is a broad-spectrum aminocyclitol antibiotic. Its use in agriculture has led to widespread resistance in enteric bacteria, necessitating the development of more effective analogs. Aminomethyl spectinomycins (amSPC) are modified spectinomycins with increased potency against many bacterial species. These species include Legionella pneumophila, which harbors a chromosomally encoded aminoglycoside modifying enzyme (AME). In this study, we follow up on this observation and examine the extent to which the amSPCs are substrates for AMEs through adenylation (ANTs) and phosphorylation (APH). APH(9)-Ia and ANT(3")(9) were expressed in E. coli BL21(DE3) and purified using the Ni-affinity chromatography. The ability of AMEs to …

Investigating The Role Of Znf384 Rearrangements In Acute Leukemia, Kirsten Dickerson

Theses and Dissertations (ETD)

Chromosomal rearrangements involving ZNF384 are the defining lesion in 5% of pediatric and adult B-cell acute lymphoblastic leukemia and tumors are characterized by aberrant myeloid marker expression. Additionally, ZNF384 rearrangements are the defining lesion in nearly half of pediatric B/myeloid mixed phenotype acute leukemia. These fusions juxtapose full-length ZNF384 to the N terminal portion of a diverse range of partners, most often, transcription factors or epigenetic modifiers. It has been shown that ZNF384-rearranged tumors have a distinct gene expression profile that is consistent between disease groups and N terminal partners. Genomic analyses of patient tumors has shown that ZNF384 fusions …

Genetic Variation And Sex Mediate Differential Responses To ∆-9-Tetrahydrocannabinol Among Inbred Mice, Cory Parks

Theses and Dissertations (ETD)

The plant Cannabis sativa has been used by people for both recreational and medicinal use for thousands of years, but scientific investigation of the plant and its components didn’t begin until the early nineteen hundreds when Cannabis components known as phytocannabinoids were characterized and later isolated. In the 1970’s, ∆9-tetrahydrocannabinol (THC) was isolated and recognized as the major constituent responsible for the psychoactive and intoxicating effects associated with consumption of cannabis. This opened the door for intensive research in the field that lead to the discovery of the endogenous cannabinoid system and its associated receptors, effectors of signaling, and biosynthetic …

Validation And Application Of A Novel Target-Based Whole-Cell Screen To Identify Antifungal Compounds, Christian Alexander Dejarnette

Theses and Dissertations (ETD)

Traditional approaches to drug discovery are inefficient and have several key limitations that constrain our capacity to rapidly identify and develop novel experimental therapeutics. To address this, we have devised a second-generation target-based whole-cell screening assay based on the principles of competitive fitness, which can rapidly identify target-specific and physiologically-active compounds. Briefly, strains expressing high, intermediate, and low levels of a preselected target protein were constructed, tagged with spectrally distinct fluorescent proteins (FPs), and mixed together. The pooled strains were then grown in the presence of various small molecules, and the relative growth of each strain within the mixed culture …

Characterization Of Novel Cb2 Agonist Smm-295 And Its Effects In Ischemia/Reperfusion Injury, Jeffrey D. Pressly

Theses and Dissertations (ETD)

Acute kidney injury (AKI) is a major problem clinically affecting up to two-thirds of intensive care unit patients, and results in increased hospitalization time, the risk of developing chronic kidney disease, and mortality. Hallmarks of AKI include tubular cell death and a decrease in renal perfusion which leads to decreases in renal function following injury. For 20 years the pathophysiology of AKI has been well established. However, therapies for AKI have shown minimal to no success clinically. The work here describes our efforts to further categorize the effects of CB2 activation, a possible novel therapeutic target in AKI.

There is …

Characterization Of The Hepatotoxicity Of Rifampicin And Isoniazid, Christopher T. Brewer

Theses and Dissertations (ETD)

In a mouse model, rifampicin and isoniazid combination treatment results in cholestatic liver injury that is associated with an increase of protoporphyrin ix (PPIX), the penultimate heme precursor. Excess PPIX is believed to bind to bile acids, precipitate in bile canaliculi, and form bile plugs leading to cholestasis fol owed by liver injury. Both ferrochelatase (FECH/Fech) and aminolevulinic acid synthase 1 (ALAS1/Alas1) are crucial enzymes in regulating heme biosynthesis. Isoniazid has recently been reported to up-regulate Alas1 but down-regulate Fech protein levels in mice; however the mechanism of isoniazid mediated heme synthesis …

Habituation And Dishabituation In The Olfactory Bulb: From Neural Responses To Behavior, Mary Cameron Ogg

Theses and Dissertations (ETD)

Habituation and dishabituation modulate the neural resources and behavioral significance allocated to incoming stimuli across the sensory systems. The purpose of the research presented in this dissertation was to characterize these processes in the mouse olfactory bulb (OB) and to determine if OB acetylcholine (ACh) has a role in physiological and behavioral olfactory dishabituation. Calcium imaging was used to determine the timecourse and magnitude of habituation in different parts of the OB during and after a prolonged odor presentation. Widefield imaging of the dendritic, or glomerular, response of OB output cells demonstrated that prolonged odor input habituates glomerular responses during …

Using S. Pombe To Study The Biological Roles Of The Histone Deacetylases Sir2 And Clr3 And The Dead-Box Rna Helicase Ded1, Brandon Ray Lowe

Theses and Dissertations (ETD)

The fission yeast Schizosaccharomyces pombe provides a good model system to quickly study basic mechanisms underlying biological pathways conserved in higher eukaryotes. Here we utilized fission yeast to study the roles of the histone deacetylases (HDACs) Sir2 and Clr3 in heterochromatin formation and cancer associated mutations of the DEAD-box RNA helicase DDX3X, homolog of fission yeast Ded1, in translational control. Heterochromatin in fission yeast is characterized by hypoacetylation as well as methylation of histone H3 on lysine 9 (H3K9me). Heterochromatin assembly can now be separated into three distinct steps: heterochromatin establishment, spreading, and maintenance. These steps involve the actions of …

Investigating The Role Of Dispatched In Hedgehog Ligand Transport And Delivery, William Bodeen

Theses and Dissertations (ETD)

During the development of all metazoans, the Hedgehog (Hh) signaling pathway provides instructional cues influencing a variety of cellular processes. The pathway ligand, Hh, is dually lipidated by cholesterol and palmitate, which effectively anchors the molecule to the lipid bilayer of the signal producing cell. To complicate the Hh pathway induction process, the Hh ligand is often produced at a significant distance from the cells it influences. Only one known conserved molecule, Dispatched (Disp), can alleviate the membrane tethering imparted by Hh lipidation. Underscoring the importance of Disp protein during development, knockout animals succumb to lethality at E9.5, an exact …

Antibiotic Drug Discovery With An Eye Towards Overcoming Drug Resistance, Daniel Towner Hoagland

Theses and Dissertations (ETD)

As a species, humans have become ever reliant on the use of antibiotics to facilitate our everyday lives. The widespread emergence of resistance to currently used antibiotics is commonly attributed to an over use in our society. Such resistance, coupled with a lack of innovation and production of novel antibiotic drugs, threatens to return humanity to an era similar to one before the discovery of the first antibiotics. The need to find new agents to be used in this fight is paramount, as well as learning from our recent failures to produce such compounds. This document will highlight my efforts …

Interaction Between Two E3 Ligases, Nedd8ylated Cullin And Hhari, Kheewoong Baek

Theses and Dissertations (ETD)

RBR (RING1-in between RING-RING2) is a special type of E3 ubiquitin ligase containing three zinc-binding RING (Really Interesting New Gene) domains, while adopting mechanisms of HECT (Homologous to E6-AP Carboxyl Terminus) for substrate ubiquitination. Most well known RBRs include Parkin and HOIP, which are associated with Parkinson’s disease and innate immune deficiency. However, it is not well known how the RBR proteins gain activity, as they are known to be autoinhibited. Here I show that a specific F430A, E431A, E503A triple mutation of RBR protein HHARI (Human homologue of Ariadne) and its interaction with NEDD8ylated cullin RING ligase can both …

Antibodies To Heterogenous Nuclear Ribonucleoprotein A1 Penetrate Neurons Leading To Multiple Downstream Effects Resulting In Neurodegeneration, Joshua Nathan Douglas

Theses and Dissertations (ETD)

Multiple sclerosis (MS) is the most common demyelinating disorder of the central nervous system. MS is believed to occur in genetically susceptible individuals due to an unknown environmental stimulus. MS patients produce autoantibodies to heterogenous nuclear ribonuclearprotein A1 (hnRNP A1), an RNA binding protein (RBP) highly expressed in neurons. hnRNP A1 functions in pre-mRNA splicing, mRNA trafficking, and translation. Furthermore, the anti-hnRNP A1 antibodies are specific to a N-terminal region termed ‘M9’ which serves as a nuclear export sequence/nuclear localization sequence (NES/NLS) responsible for nuclear/cytoplasmic transport of the protein. In this manuscript we will provide data revealing that anti-hnRNP A1 …

Mrp4-Dependent Regulation Of Fibroblast Migration, Chandrima Sinha

Theses and Dissertations (ETD)

Roles of cyclic nucleotides and cyclic nucleotide-dependent signaling molecules in regulating several signaling pathways including cell migration have long been known. However, the new and revolutionary concept is that it is not just the absence or presence of cyclic nucleotides, but a highly coordinated balance between these molecules regulates cell migration. Multi-drug resistance protein 4 (MRP4), is a member of the large family of ATP binding cassette (ABC) transporter proteins, that localizes to the plasma membrane and functions as a nucleotide efflux transporter and thus plays a pivotal role in the regulation of intracellular cyclic nucleotide dynamics. In our study …

Strengths And Weaknesses Of Hybrid Tpr Technology For Obtaining Structural And Mechanistic Insights Into Tpr Proteins, Shanshan Yu

Theses and Dissertations (ETD)

Tetratricopeptide (TPR) repeats are a 34-residue helix-turn-helix motif that when repeated pack into a superhelical structure. TPR domains are frequently found mediating protein-protein interactions, often through a central groove. One protein complex bearing numerous TPR repeats is the Anaphase Promoting Complex (APC). The anaphase-promoting complex (APC) is a multi-subunit complex, which orchestrates mitotic cell cycles. APC is an E3 ligase in the ubiquitin cascade, and directs the 26S proteosome degradation of cell-cycle regulators. Throughout mitotic progression, proteins that are key regulators of the cell cycle are assembled with polyubiquitin chains by APC.

One domain of the human APC is comprised …

Erg11-Mediated Azole Resistance In Candida Albicans, Stephanie Ann Flowers

Theses and Dissertations (ETD)

Although many medically important Candida species are commensal to the gut or colonizers of the skin, these organisms have the propensity to cause disease in the event of a waning immune system. Clinical manifestations of infections with Candida species can range from superficial mucosal infections to deep organ involvement usually resulting from haematogenous spread of infection. Despite significant progress made in the management of patients with fungal infections, the emergence of antifungal resistant clinical isolates creates significant problem in regards to antifungal prophylaxis and empirical treatment strategies. Antifungal resistance is associated with high mortality rates and hefty medical costs. The …

Full-Gestational Exposure To Nicotine And Ethanol Results In Long-Term Dysregulation In The Ventral Tegmental Area, Emily Elizabeth Roguski

Theses and Dissertations (ETD)

Nicotine is considered a gateway drug for other drugs of abuse. The majority of smokers that begin smoking in adolescence, continue into adulthood. Multiple factors have been linked with smoking initiation, including maternal smoking. Drug exposure during pregnancy has long been suspected to exert deleterious effects on the fetal brain. Concurrent use of smoking and drinking alcohol throughout pregnancy is an all too frequent occurrence in the human population especially in disadvantaged and younger women.

The present study investigated the potential contributing factors for the enhanced nicotine selfadministration as seen in offspring with gestational exposure to nicotine and ethanol (Nic+EtOH).* …

The Protumorigenic Role Of Caspase-8 In Neuroblastoma, Devin Drew Twitchell

Theses and Dissertations (ETD)

Neuroblastoma (NB), the most common extracranial solid tumor in children, accounts for 15% of cancer-related deaths in pediatric patients. Caspase-8 (casp8), a proapoptotic protein, is silenced in approximately, 50-70% of neuroblastoma patient samples. Loss of casp8 has been suggested to increase NB metastasis and correlated, in some studies, with advanced-stage NB. Furthermore, decreased casp8 expression may facilitate neuroblastoma tumorigenesis by protecting cells from cell death mediated by either integrins or chemotherapeutics. Paradoxically, casp8 expression is maintained in 30-50% of NB patient samples giving rise to the possibility that casp8 may provide selective advantages for NB tumorigenesis. Caspase-8 is shown to …

Mrp4 Is A Crucial Regulator Of Testosterone Biosynthesis, Jessica Ann Morgan

Theses and Dissertations (ETD)

The physiological role of multidrug resistance protein 4 (Mrp4) in the testes is unknown. It was discovered that Mrp4 is expressed primarily in mouse and human Leydig cells; however, there is no current evidence that Mrp4 regulates testosterone biosynthesis. The role of Mrp4 was investigated in Leydig cells where testosterone production is regulated by cAMP, an intracellular second messenger formed when the luteinizing hormone (LH) receptor (Lhr) is activated. As Mrp4 regulates cAMP, we compared testosterone levels in our Mrp4 WT and KO mice. Prepubertal KO mice had significantly reduced testicular testosterone, impaired gametogenesis, and disrupted cAMP homeostasis, resulting in …

The Role Of The Yxxφ Motif In Cd82 Trafficking And Function, Mekel Marie Richardson

Theses and Dissertations (ETD)

CD82, a tetraspanin, is a tumor metastasis suppressor. Tetraspanins are membrane spanning proteins that play critical roles in diverse biological and pathological processes, e.g., the regulation of cancer metastasis. CD82 is ubiquitously expressed in various types of tissues, but its expression becomes down-regulated or lost in a majority of metastatic tumors. It inhibits tumor metastasis without affecting primary tumor growth. Cancer patients whose tumors contain CD82 exhibit minimal metastasis. We know that CD82 functions as a tumor metastasis suppressor but the mechanism by which this occurs is largely unknown. CD82 can be found on the plasma membrane as well as …

Discovery Of Dihydroartemisinin And Dasatinib Drug Combination To Cure Pooroutcome Bcr-Abl+ Acute Lymphoblastic Leukemia, Harpreet Singh

Theses and Dissertations (ETD)

Oncogenic signaling by the Philadelphia chromosome-encoded BCR-ABL fusion kinase initiates and drives both Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic myelogenous leukemia (CML). Food and Drug Administration (FDA)- approved BCR-ABL-specific kinase inhibitors (BCR-ABL–KIs) imatinib, dasatinib and nilotinib induce prolonged remissions in CML but poor leukemia-reduction and relapse-control in Ph+ ALL. The relative primary BCR-ABL–KI-resistance in Ph+ ALL patients carrying predominantly BCR-ABLWT disease cannot be attributed to drug-resistant BCR-ABL mutations (BCR-ABLMUTANTS), and remains poorly understood.

We established a cell-based platform to evaluate the modulation of anti-Ph+ ALL activity of drugs by both tumor-extrinsic cytokines normally present in the leukemia …

Acetaldehyde And Epithelial Junctions: Role Of Pp2a And Occludin Phosphorylation, Mitzi Dunagan

Theses and Dissertations (ETD)

Chronic alcohol consumption causes health problems including cancers, liver damage, and cirrhosis.These problems are exacerbated by endotoxins from the bacterial population of the colon, which can enter the bloodstream when gastrointestinal tight junctions, protein complexes that prevent paracellular passage of molecules, are compromised. The mechanisms of this barrier disruption are the subject of current study.

Acetaldehyde, produced as a result of ethanol breakdown by intestinal microflora as well as intestinal epithelia, is a known carcinogen. It compromises the barrier function of intestinal epithelial cells by causing irregularities in the phosphorylation of tight junction proteins. It also reacts with proteins, lipids, …

The Molecular Basis Of Fitness And Transmissibility Of Neuraminidase Inhibitor Resistant Influenza A Viruses, Susu Duan

Theses and Dissertations (ETD)

Neuraminidase (NA) inhibitors including oral oseltamivir and inhaled zanamivir are among the first line of defense against influenza virus infection. Development of resistance to NA inhibitors is a huge drawback for limited options for the control of influenza. During the first decade of NA inhibitor use, the detection rates of resistance to both NA inhibitors had remained low in circulating influenza viruses. However, the 2008~2009 season was marked by a radical increase of prevalence of oseltamvir resistance from <1% to >90% in worldwide surveillance in less than a year. The resistance was solely linked to NA H275Y variants of seasonal H1N1 viruses, …

Characterization Of The Mechanism Of Pparγ-Mediated Neointima Formation In Rodents, Ryoko Tsukahara

Theses and Dissertations (ETD)

Lysophosphatidic acid (LPA) and its ether analog alkyl glycerophosphate (AGP) elicit arterial wall remodeling when applied intralumenally into the uninjured carotid artery. LPA is the ligand of eight GPCRs and the peroxisome proliferator-activated receptor γ (PPARγ). We pursued a gene knockout strategy to identify the LPA receptor subtypes necessary for the neointimal response in a non-injury model of carotid remodeling and also compared the effects of AGP and the PPARγ agonist rosiglitazone (ROSI) on balloon injury-elicited neointima development. In the balloon injury model AGP significantly increased neointima; however, rosiglitazone application attenuated it. AGP and ROSI were also applied intralumenally for …

Compound 49b: A Novel Beta-Adrenergic Receptor Agonist In The Treatment Of Diabetic Retinopathy, Kimberly Williams-Guy

Theses and Dissertations (ETD)

Diabetic retinopathy is the leading cause of blindness in working Americans. While there are therapeutic regimens for the disease, more effective methods are needed. We have previously shown that a non-specific beta-adrenergic receptor agonist, isoproterenol, was effective in preventing functional and morphological changes associated with diabetic retinopathy in the rat. Isoproterenol also produced left ventricle remodeling suggesting it entered the systemic circulation. We therefore synthesized various novel beta-adrenergic receptor compounds and screened these compounds in vitro for their ability to reduce markers of inflammation and apoptosis. Of the various compounds tested, Compound 49b was able to reduce both inflammation and …

Novel Insights Into Ubiquitin-Like Protein E1-E2 Interactions, Asad Taherbhoy

Theses and Dissertations (ETD)

Posttranslational modification of macromolecules by ubiquitin-like proteins (UBLs) such as ubiquitin, Sumo and NEDD8 regulate a vast array of processes in the cell. Transfer of UBLs to their target generally occurs by a series of molecular handoffs down an E1‑E2‑E3 cascade. We are interested in understanding how E1‑E2 pairs interact and mediate UBL transfer. To this effect, we studied two E1‑E2 pairs: the Sumo pathway (Sumo utilizes a canonical E1 and E2) and the Atg8 pathway (Atg8 is a UBL involved in autophagy that utilizes a non-canonical E1‑E2 pair).

Sumo conjugation is initiated by the heterodimeric Aos1‑Uba2 E1 enzyme (in …

Inflammatory Proteins, Genetic Variation, And Environmental Influences On Health Care Associated Infection Development In Sepsis, Reba Antoinette Umberger

Theses and Dissertations (ETD)

The purpose of this study was to determine the impact of baseline systemic inflammation (pro‑inflammatory cytokine, anti‑inflammatory cytokine, and their ratio), genetic variability, and environment on the development of health care associated infections (HAI) among sepsis patients during their ICU stay (up to 28 days).

Methods: A prospective observation study was conducted at the Veterans Affairs Medical Center in the Medical Intensive Care Unit over an 18 month period. A total of 78 patients were enrolled within 72 hours of presenting to the ICU with sepsis. Patient were excluded if they were receiving immunosuppressants (chemotherapy or greater than one mg/kg …

The Design And Synthesis Of Autotaxin Inhibitors And Analogs Of Lysophosphatidic Acid, Renuka Niranjan Gupte

Theses and Dissertations (ETD)

Lysophosphatidic acid (LPA) is a naturally occurring bioactive phospholipid. It has a wide array of biological effects like cell proliferation, survival, migration, apoptosis invasion, wound healing and angiogenesis. Autotaxin (ATX) was identified as an autocrine tumor cell motility factor from A2058 melanoma conditioned medium. ATX has lysophospholipase D enzyme activity and is responsible for the cleavage of lysophophatidylcholine (LPC) leading to the generation of LPA. Antagonists of Autotaxin would have a potential therapeutic application in cancer research. Chapter 1 is an introduction of LPA and autotaxin. It provides the background and significance of the research. Chapter 2 explores the synthesis …

Discovery Of Quinic Acid Derivatives As Oral Anti-Inflammatory Agents, Kui Zeng

Theses and Dissertations (ETD)

Quinic acid (QA) esters found in hot water extracts of Uncaria tomentosa (a.k.a. Cat’s claw) exert anti-inflammatory activity through mechanisms involving inhibition of the pro-inflammatory transcription factor nuclear factor kappa B (NF-κB). Herein, we described the synthesis and biological testing of novel QA derivatives. Inhibition of NF-κB was assessed using A549 (Type II alveolar epithelial-like) cells that stably express a secreted alkaline phosphatase (SEAP) reporter driven by an NF-κB response element. A549- NF-κB cells were stimulated with TNF-α (10 ng/mL) in the presence or absence of QA derivative for 18 hours followed by measurement of SEAP activity. Amide substitution at …

The Role Of Interferon Gamma In The Regulation Of Il-18 Binding Protein And The Development Of Autoimmune Arthritis In A Genetically Non-Susceptible Mouse Strain, Timothy Daniel Kayes

Theses and Dissertations (ETD)

The etiology of the autoimmune disease rheumatoid arthritis (RA) is unknown, but the role of cytokines, including IFN-g, as effectors of immune cell function has been established by the examination of cytokine production in RA patients and through the use of animal models. C57BL/6 (B6) mice that express MHC class II molecules of the b haplotype (I-A^b) are not typically susceptible to collagen-induced arthritis (CIA), the most widely studied animal model of RA. When the gene encoding IFN-g is removed by genetic deletion, however, susceptibility to CIA is conferred. In addition, T cell responses against the immunogen that …

Contribution Of Organic Cation Transporter 2 (Oct2) To Cisplatin-Induced Nephrotoxicity, Kelly K. Filipski

Theses and Dissertations (ETD)

Cisplatin is the most widely used anticancer agent; however, the cellular pharmacokinetics are poorly understood. Cisplatin is predominantly eliminated through the urine via active secretion and is associated with nephrotoxicity. Currently, prehydration therapy is employed to prevent toxic renal side effects; however it has not been completely ameliorated. The studies described herein aim to determine the mechanism in which cisplatin enters the kidney cell from the blood and how it is subsequently secreted into the urine. Organic cation transporter 2 (OCT2) and ABCC2 are highly expressed in the kidney on the basolateral and apical membrane, respectively. We determined the contribution …