Digital Commons Network^™

Mercury Bioaccumulation In Bat Populations In Mammoth Cave National Park: Modern, Historical, And Ancient Samples, Stephanie Hagan

Mahurin Honors College Capstone Experience/Thesis Projects

The first human to enter Mammoth Cave passed under its arch about 4,000 years ago, but bats have been calling it home long before humans discovered it. Due to environmental exposure of mercury, these bats potentially show substantial mercury bioaccumulation. Bats now come into contact with mercury through atmospheric deposition from industrial sources. It is expected that the modern bats residing in Mammoth Cave should have measurable levels of mercury in their system which has been determined by guano analysis. Over fifty current samples of bat guano have been analyzed and exhibit mercury levels at the part per billion level. …

Herbal And Holistic Medicine In Latin America, William H. Lyle

Mahurin Honors College Capstone Experience/Thesis Projects

A variety of herbal and holistic remedies were used in pre-Columbian cultures, especially in Aztec and Incan cultures. Many different herbs were used to provide medical attention to patients directly, while other herbs were used to supplement shaman^[1] medicine, which was particularly common in Inca culture. While there is little scientific basis for shamanism, as a viable healing option in modern culture, most herbal remedies had active chemical ingredients that could be or are used today to treat similar symptoms, and, in some cases, are being applied in different scenarios as well. The methods of usage, active chemicals, and …

Cu (Ii) Catalyzed Gateways In The Synthesis Of Acridine Derivatives And Their Biological Evaluation As Anti-Cancer Drugs, Rajesh Komati

LSU New Orleans Theses and Dissertations

Telomeres are nucleoprotein complexes found at the ends of linear eukaryotic chromosomes. Telomeres consist of a short sequence of repetitive double stranded DNA, TTAGGG repeats in humans (and all mammals), and a complex of 6 proteins, termed the shelterin complex. The length of the telomeres varies greatly between species, from approximately 300 base pairs in yeast to many 10-15 kilo bases in humans, because of the end replication problem this length get shorten with each cell division and ultimately leads to cell death. However the immortal eukaryotic cells and some transformed human cells over come this incomplete end replication problem …

Design, Synthesis And Biological Evaluation Of Novel Compounds With Cns-Activity Targeting Cannabinoid And Biogenic Amine Receptors, Alexander M. Sherwood

LSU New Orleans Theses and Dissertations

This work seeks to contribute to the discipline of neuropharmacology by way of structure activity relationship from the standpoint of an organic chemist. More specifically, we sought to develop robust synthetic methodology able to efficiently produce an array of compounds for the purpose of systematic evaluation of their interaction with specific sights within the central nervous system (CNS) in order to better understand the mind and to develop drugs that may have beneficial effects on neurological function.

The focus of these studies has been toward the development of novel molecules, using a structure-activity relationship approach, that exhibit binding affinity at …

X-Ray Structure Analysis And Topological Charge Density Studies Of Gossypol Derivatives, Carlos Zelaya

LSU New Orleans Theses and Dissertations

Gossypol and gossypol derivatives are natural byproducts of a variety of cotton plant species that poses interesting chemical, biological, and medicinal properties that are currently heavily researched. Supporting evidence suggest that gossypol and gossypol derivatives act on the Bcl-2 proteins that have been linked to certain cancers. Gossypol amine derivatives, specifically, are actively researched and a variety of amine derivatives have already been synthesized. However, gossypol and its derivatives are challenging compounds to work with because many of its derivatives tend to exist in various tautomeric forms. When analyzing gossypol and its derivatives it is the complex electron configuration that …

Glass Foundation Chemosensor Synthesis And Functionality Analysis, Justin D. Dancer

Master's Theses

Chemosensors are created through a series of reaction steps on controlled pore class (CPG) and terminate with a Cu²⁺ metal binding site. Each monolayer of reactant insures that the metal binding site exposed to solution would serve as an indicator displacement assay (IDA) sensor. The purpose of this research is to create a molecular sensor with a high density of terminal metal sites to quantify bidentate substrates. To accomplish this, each synthetic step of the sensor is examined in order to test the effects of new linkers, ligands, and variously sized dendrimers to see if small structural changes could …

Carbon Sequestration In Tidal Salt Marshes And Mangrove Ecosystems, Carlos Eduardo Quintana-Alcantara

Master's Projects and Capstones

Wetlands are dynamic systems that provide support to vital environmental functions and services. Wetlands take part in the global carbon cycle by holding organic carbon in biomass, soils and sediments. In recent years, the wetland carbon sequestration capacity has been researched worldwide due to the increase of the concentrations of greenhouse gasses implicated in global warming and climate change. Although coastal wetlands release the greenhouse gasses carbon dioxide, methane and nitrous oxide, these ecosystems maintain high performance in offsetting significant amounts of atmospheric carbon. This paper investigated the carbon sequestration capacity of coastal wetland ecosystems summarizing the environmental conditions and …

Mobilization Of Toxic Elements From An Abandoned Manganese Mine In The Arid Metropolitan Las Vegas (Nv, Usa) Area, Ji Hye Park, Vernon Hodge, Shawn Gerstenberger, Krystyna Stave

Chemistry and Biochemistry Faculty Research

Active and abandoned mines may present health risks, especially to children, from environmental exposure to airborne chemical elements, such as Pb, As, and Mn. X-ray fluorescence analysis of tailings at the Three Kids Mine show they contain high levels of: Pb (15,300 mg/kg), As (3690 mg/kg), and Mn (153,000 mg/kg). Soil was sampled along eight transects, radiating from the dried tailings ponds. Concentrations of Mn and Pb to the NE are at background concentrations at 4.8 km, and, As and Sr at 3.2 km from the mine. Going SW to the City of Henderson, all elements are at background at …

Characterization Of Suf Pathway For Fe-S Cluster Assembly In Escherichia Coli, Yuyuan Dai

Theses and Dissertations

Fe-S clusters are critical metallocofactors required for cell function. Because of the toxicity of ferrous iron and sulfide to the cell, in vivo Fe-S cluster assembly is carried out by multiprotein biosynthetic pathways. Escherichia coli contains a stress-responsive Fe-S cluster assembly system, the SufABCDSE pathway, working under iron starvation and oxidative stress conditions. The cysteine desulfurase SufS and its accessory protein SufE work together to mobilize persulfide from L-cysteine. We collaborated with Dr. Laura S. Busenlehner to use hydrogen/deuterium exchange mass spectrometry (HDX-MS) to characterize SufS-SufE interactions and protein dynamics. HDX-MS analysis shows that SufE binds near the SufS active …

Suzuki-Miyaura Reactions Are Used To Synthesize Z-Alkenes From Cyclic Boronic Half-Acids, Daniel Lee French

Undergraduate Honors Thesis Collection

Cis-Alkenes provide the basic structure and reactivity for a variety of compounds, from the common chemicals found in any organic laboratory to advanced drugs used to treat cancer or suppress the immune system (Littke & Fu, 2002). Synthetically, alkenes are also of use in that they serve as a site for further chemistry. Historically, Z-alkenes have been more difficult to synthesize than their E-counterparts (McNulty et al., 2010; Siau, Zhang, & Zhao, 2012). Furthermore, in many reactions, a mixture of E- and Z- conformations of the alkene is produced. Such differences may seem trivial upon first inspection, but because there …

The Dimerization Domain In Dape Enzymes Is Required For Catalysis, Boguslaw Nocek, Anna Starus, Magdalena Makowska-Grzyska, Blanca Gutierrez, Stephen Sanchez, Robert Jedrzejczak, Jamey C. Mack, Kenneth W. Olsen, Andzrej Joachimiak, Richard C. Holz

Chemistry Faculty Research and Publications

The emergence of antibiotic-resistant bacterial strains underscores the importance of identifying new drug targets and developing new antimicrobial compounds. Lysine and meso-diaminopimelic acid are essential for protein production and bacterial peptidoglycan cell wall remodeling and are synthesized in bacteria by enzymes encoded within dap operon. Therefore dap enzymes may serve as excellent targets for developing a new class of antimicrobial agents. The dapE-encoded N-succinyl-L,L-diaminopimelic acid desuccinylase (DapE) converts N-succinyl-L,L-diaminopimelic acid to L,Ldiaminopimelic acid and succinate. The enzyme is composed of catalytic and dimerization domains, and belongs to the M20 peptidase family. To understand the specific role …

Reclaiming The Efficacy Of Β-Lactam–Β-Lactamase Inhibitor Combinations: Avibactam Restores The Susceptibility Of Cmy-2-Producing Escherichia Coli To Ceftazidime, Krisztina M. Papp-Wallace, Marisa L. Winkler, Julian A. Gatta, Magdalena A. Taracila, Sujatha Chilakala, Yan Xu, J. Kristie Johnson, Robert A. Bonomo

Chemistry Faculty Publications

CMY-2 is a plasmid-encoded Ambler class C cephalosporinase that is widely disseminated in Enterobacteriaceae and is responsible for expanded-spectrum cephalosporin resistance. As a result of resistance to both ceftazidime and β-lactamase inhibitors in strains carrying blaCMY, novel β-lactam–β-lactamase inhibitor combinations are sought to combat this significant threat to β-lactam therapy. Avibactam is a bridged diazabicyclo [3.2.1]octanone non-β-lactam β-lactamase inhibitor in clinical development that reversibly inactivates serine β-lactamases. To define the spectrum of activity of ceftazidime-avibactam, we tested the susceptibilities of Escherichia coli clinical isolates that carry blaCMY-2 or blaCMY-69 and investigated the inactivation kinetics of CMY-2. Our analysis showed that …

2-Acylamido Analogues Of N-Acetylglucosamine Prime Formation Of Chitin Oligosaccharides By Yeast Chitin Synthase 2, Jacob Gyore, Archana Parameswar, Carleigh Hebbard, Younghoon Oh, Erfei Bi, Alexei Demchenko, Neil Price, Peter Orlean

Chemistry & Biochemistry Faculty Works

Chitin, a homopolymer of β1,4-linked N-acetylglucosamine (GlcNAc) residues, is a key component of the cell walls of fungi and the exoskeletons of arthropods. Chitin synthases transfer GlcNAc from UDP-GlcNAc to preexisting chitin chains in reactions that are typically stimulated by free GlcNAc. The effect of GlcNAc was probed by using a yeast strain expressing a single chitin synthase, Chs2, by examining formation of chitin oligosaccharides (COs) and insoluble chitin, and by replacing GlcNAc with 2-acylamido analogues of GlcNAc. Synthesis of COs was strongly dependent on inclusion of GlcNAc in chitin synthase incubations, and N,N′-diacetylchitobiose (GlcNAc2) was the major reaction product. …

Molecular Modeling Of Biological Carbon Fixation, William Lin, Andrew Kim, Scott Hansen

CLAS: Colby Liberal Arts Symposium

Biological carbon fixation is primarily catalyzed by one enzyme: ribulose-1,5-bisphosphate carboxylase oxygenase. We use molecular modeling to explore and elucidate the origin of slow kinetics and poor specificity in this enzyme. We present primary results of correlated motion between the enzyme and the active site.

Cyanide Toxicokinetics: The Behavior Of Cyanide, Thiocyanate And 2-Amino-2-Thiazoline-4-Carboxylic Acid In Multiple Animal Models, Raj K. Bhandari, Robert P. Oda, Ilona Petrikovics, David E. Thompson, Matthew Brenner, Sari B. Mahon, Vikhyat S. Bebarta, Gary A. Rockwood, Brian A. Logue

Chemistry and Biochemistry Faculty Publications

Cyanide causes toxic effects by inhibiting cytochrome c oxidase, resulting in cellular hypoxia and cytotoxic anoxia, and can eventually lead to death. Cyanide exposure can be verified by direct analysis of cyanide concentrations or analyzing its metabolites, including thiocyanate (SCN⁻) and 2-amino-2-thiazoline-4-carboxylic acid (ATCA) in blood. To determine the behavior of these markers following cyanide exposure, a toxicokinetics study was performed in three animal models: (i) rats (250–300 g), (ii) rabbits (3.5–4.2 kg) and (iii) swine (47–54 kg). Cyanide reached a maximum in blood and declined rapidly in each animal model as it was absorbed, distributed, metabolized and …

Green's Functions Of Discrete Fractional Calculus Boundary Value Problems And An Application Of Discrete Fractional Calculus To A Pharmacokinetic Model, Sutthirut Charoenphon

Masters Theses & Specialist Projects

Fractional calculus has been used as a research tool in the fields of pharmacology, biology, chemistry, and other areas [3]. The main purpose of this thesis is to calculate Green's functions of fractional difference equations, and to model problems in pharmacokinetics. We claim that the discrete fractional calculus yields the best prediction performance compared to the continuous fractional calculus in the application of a one-compartmental model of drug concentration. In Chapter 1, the Gamma function and its properties are discussed to establish a theoretical basis. Additionally, the basics of discrete fractional calculus are discussed using particular examples for further calculations. …

Functionalization And Modification Of Naphthaquinone Analogs As Her2 Kinase Inhibitors, Divya Jyothi Lella

Masters Theses & Specialist Projects

HER2 overexpression in breast cancer tumors predicts lower overall survival. Because of the aggressive nature of HER2 tumors and the association with metastatic disease, the HER2 receptor holds great promise as a therapeutic target in metastatic breast cancer. We are developing small molecule inhibitors that bind to the ATP binding site of the tyrosine kinase domain in order to inhibit tyrosine auto-phosphorylation. This process controls biological pathways that mediate the cell growth. In normal cells this process is highly controlled. We are targeting the modification of the side chain of the hydroxy methyl group of 2-Hydroxy methyl-5,8-dimethoxy-1,4-naphthaquinone. These compounds should …

Electrically Controlled Formation And Release Of Admicelles For Solid Phase Extraction, Sukyeon Lee

Masters Theses & Specialist Projects

Solid phase extraction is one of the most widely used methods to concentrate diluted compounds in a solution. Substances can be extracted into admicelles and hemimicelles, which are surface adsorbed micelles and surfactant monolayers, respectively. Investigations of the electrical control of surfactants on surfaces for the purpose of analyte preconcentration prior to chromatographic analysis are presented. The surfactant layer serves as the “stationary phase” in a solid phase extraction sorbent scenario. Analytes are adsorbed on this layer, and then released from the solid phase via surfactant removal. The attachment and removal of the surfactant are controlled by means of an …

Investigation Of The Addition Of Basalt Fibres Into Cement, Jahi Palme

Masters Theses & Specialist Projects

Mechanical properties of concrete are most commonly determined using destructive tests including: compression, flexure, and fracture notch specimen tests. However, nondestructive tests exist for evaluating the properties of concrete such as ultrasonic pulse velocity and impact echo tests. One of major issues with concrete (which has cement as its prime ingredient) is that unlike steel it is quasi-brittle material. It tends to want to crack when tensile stresses develop. Fibres have been added to concrete for many years to reduce the amount of and size of cracks cause by temperature changes or shrinkage. In more recent years, significant research has …

Expanding The Frontier Of Gold-Catalyzed Cyclizations And Rational Ligand Design., Deepika Malhotra

Electronic Theses and Dissertations

The focus of my dissertation work is to study the gold-catalyzed intramolecular and intermolecular cyclizations involving oxonium intermediates towards the application of synthetically interesting frameworks under ambient conditions and developing a rational approach for the effective catalyst design in gold catalysis. We explored the goldcatalyzed oxygen-transfer reactions of 2-alkynyl-1,5-diketones or 2-alkynyl-5-ketoesters to furnish five-membered rings bearing a quaternary carbon tethered to a carbonyl group. The detailed mechanistic investigation on the newly proposed intramolecular [4+2] cycloaddition mechanism was performed by means of isotopic experiments and quantum chemical calculations. The reactivity of alkynylenolate was investigated in the reactions of allenic ketones and …

Ligand Centered Reactivity Of Metal Stabilized Thiyl Radicals In Solution, Solid And Gaseous Phase., Rajat Rajat

Electronic Theses and Dissertations

This thesis presents ligand centered reactivity studies of metal stabilized thiyl radicals in solution, solid, and gaseous phases for catalysis and sensing based applications. Chemical oxidation of tris(2-diphenylphosphinebenzenethiolato )ruthenate(II) [Ru -1]- with ferrocenium hexafluorophosphate in the presence of ethylene yields [Ru-1·C,H.]PF6, from addition of the alkene across cis sulfur sites. In the presence of base [Ru-1·C,H.]+ is selectively deprotonated at the pseudoequatorial proton on the carbon a to the sulfur trans to phosphorus, yielding the vinyl metallosulfonium derivative [Ru-1·C,H3]. "H and 31p NMR spectra of [Ru-1'C,H3 ] are temperature dependent, associated with inversion of the sulfur lone pair at the …

Synthesis Of N-Heterocycles Through Cyclization-Triggered Tandem Additions To Alkynes And The Study Of Promoters In Ionic Reactions., Junbin Han

Electronic Theses and Dissertations

Our research mainly focused on three parts related to the rapid construction of N-heterocycles and the search for ionic reaction promoters. First, N-heterocycles of different ring sizes and with different substitution patterns constitute extremely important structure classes (e.g., alkaloids) in the search for bioactivity. A contemporary challenge in organic synthesis is the mapping of new chemical spaces through tandem or cascade reactions in an atom economical fashion. Our strategy to access these biologically important heterocycles is through a cyclization-triggered tandem addition to alkynes catalyzed by readily available alkynophilic coinage metals like copper. In this manner, a variety of functional groups …

Selective Oxidations By Metalloporphyrins And Metallocorroles, Tse-Hong Chen

Masters Theses & Specialist Projects

Highly reactive transition metal-oxo intermediates are important active oxidant involved in numerous enzymes such as cytochrome P450 monooxygenases as well as in many useful metal-catalyzed oxidations. Many transition metal catalysts are designed for biomimetic studies of the predominant oxidation catalysts in Nature, the cytochrome P450 enzymes. In this work, a series of metalloporphyrin and metallocorrole complexes have been successfully synthesized and spectroscopically characterized by UV-vis, GCMS and ¹H-NMR. The utilization of these complexes as catalysts for selective oxidation of sulfides and photocatalytic aerobic oxidations of activated hydrocarbons were investigated. Ruthenium(II) porphyrin complexes (2) and iron(III) corrole complexes (4) with …

Thermal Analysis Of Binding Of Organic Pollutants To Titanium Dioxide, Shashidhar Annarapu

Masters Theses & Specialist Projects

Conventional waste water treatment processes are not completely effective in removing highly stable organic compounds. Photocatalytic degradation on titanium dioxide is a possible alternative technique for many classes of these compounds. Several studies have been done by other researchers to study mechanisms of photocatalytic degradation, which occurs either through direct oxidation by holes or via indirect oxidation by radical messengers. Titanium dioxide can oxidize substrates directly through hole oxidation mechanisms or indirectly through free radical mechanisms. Substrates must bind onto the catalyst surface to undergo direct oxidation by holes. Thermogravimetric analysis (TGA) was performed on four different classes of compounds; …

Spontaneous Transfer Of Chirality In An Atropisomerically Enriched Two-Axis System, K. T. Barrett, A. J. Metrano, Paul R. Rablen, S. J. Miller

Chemistry & Biochemistry Faculty Works

One of the most well-recognized stereogenic elements in a chiral molecule is an sp(3)-hybridized carbon atom that is connected to four different substituents. Axes of chirality can also exist about bonds with hindered barriers of rotation; molecules containing such axes are known as atropisomers(1). Understanding the dynamics of these systems can be useful, for example, in the design of single-atropisomer drugs(2) or molecular switches and motors(3). For molecules that exhibit a single axis of chirality, rotation about that axis leads to racemization as the system reaches equilibrium. Here we report a two-axis system for which an enantioselective reaction produces four …

Determination Of Pore Size Distribution In Capillary-Channeled Polymer (C-Cp) Fiber Stationary Phases By Inverse Size-Exclusion Chromatography (Isec) And The Study Of The Role Of Interstitial Fraction On C-Cp Fibers On Protein Binding Capacity, Zhengxin Wang

All Theses

ABSTRACT High performance liquid chromatography (HPLC), first used in the 1960's, is a rapidly evolving analytical technique, widely employed for identification, separation, and purification in biotechnology and pharmaceutical industries. The development of the stationary phases has played an important role in improving this technique. Each stationary phase will have its own disadvantages. Polysaccharide-based stationary phases such as cross-linked dextran cannot tolerate high pressures and linear velocities; silica stationary phases are rigid enough but slow mass transfer in the pores on the surface causes another problem; with the introduction of non-porous and small bead packing materials, the low surface area and …

Assessing College Students' Understanding Of Acid Base Chemistry Concepts, Yanjun Wan

All Dissertations

Typically most college curricula include three acid base models: Arrhenius', Bronsted-Lowry's, and Lewis'. Although Lewis' acid base model is generally thought to be the most sophisticated among these three models, and can be further applied in reaction mechanisms, most general chemistry curricula either do not include Lewis' acid base model, or quickly mention it at the end of the acid base chapter, because of the concern that Lewis' model may confuse general chemistry students (Shaffer 2006). While such a disconnection in curriculum might put students to disadvantage as they try to construct solid and coherent acid base mental models, there …

Elucidation Of The Substrate Recognition Mechanism Of Vccry1, Rohe Ahmad

Theses, Dissertations and Culminating Projects

Vibrio cholerae cryptochrome 1 (VcCryl), a DNA repair enzyme, uses a lightdriven electron transfer to repair UV damaged single strand DNA but not double strand DNA. VcCryl has an active site FAD which is required for substrate binding and repair. Size exclusion chromatography (SEC) was used to observe changes in oligomer structure when changes in the oxidation state of the FAD cofactor were made. SEC studies found the oxidized state exists as a dimer with an observed mass of 163 kDa in solution, in dynamic equilibrium with a 67 kDa fragment. The reduced state exists as a monomer in …

The Role Of Stress-Activated Protein Kinases In Parasites, Tamara Kreiss

Theses, Dissertations and Culminating Projects

Lymphatic filariasis and leishmaniasis are neglected tropical diseases that are caused by nematode and protozoal parasites. These diseases cause disfiguration, leaving their host socially marked, and in some cases cause more severe disease that can lead to death. These infections, which tend to persist for long periods of time, also lead to bacterial and fungal co-infections, which further exacerbate the disease. Currently there are insufficient treatment options. Current therapies are often too expensive, have toxicity associated with them and are subjected to growing resistance amongst parasite populations. In this thesis I investigated two potential drug targets. The first, is the …

Nicotine And What Else?: Hplc Elution Optimization For The Analysis Of Alkaloids Found In Electronic Cigarettes, Jessica L. Murray

Honors Theses

Electronic cigarettes, or e-cigarettes, have been scrutinized by the Food and Drug Administration and other public health organizations for issues related to quality control and efficacy. Erratic nicotine delivery and numerous toxic compounds in refill solutions have been reported. The ultimate goal of this research is to add to the growing amount of knowledge regarding e-cigarette ingredient content, safety, and quality. Standards of the tobacco alkaloids nicotine, anabasine, cotinine, and myosmine were prepared and quantified using high performance liquid chromatography (HPLC). Various elution schemes were tested and adjusted for optimal analyte resolution, and a final elution scheme was developed to …