A5050251759- Antimicrobial Resistance in Staphylococcus
- Bacterial biofilms and quorum sensing
- Metabolomics and Mass Spectrometry Studies
- Animal Virus Infections Studies
- Viral gastroenteritis research and epidemiology
- Mass Spectrometry Techniques and Applications
- Herbal Medicine Research Studies
- Viral Infections and Immunology Research
- Alkaloids: synthesis and pharmacology
- Biochemical and Structural Characterization
- Animal Disease Management and Epidemiology
- Analytical Chemistry and Chromatography
- Ginseng Biological Effects and Applications
- Antimicrobial Peptides and Activities
- Virus-based gene therapy research
- Bacterial Identification and Susceptibility Testing
- Fungal Biology and Applications
- Natural product bioactivities and synthesis
- Microbial Natural Products and Biosynthesis
- Essential Oils and Antimicrobial Activity
- Berberine and alkaloids research
- Toxin Mechanisms and Immunotoxins
- Dermatology and Skin Diseases
- Chemical synthesis and alkaloids
- Virology and Viral Diseases
University of North Carolina at Greensboro
2015-2025
North Carolina Agricultural and Technical State University
2023
Analytical Services
2023
Greensboro College
2017-2018
Agri Food and Biosciences Institute
2009-2015
Queen's University Belfast
2009
United States Department of Veterans Affairs
1983
The Graduate Center, CUNY
1983
University of Kentucky
1983
Women's Hospital
1982
Quorum sensing peptides produced by commensal skin staphylococci protect against injury and inflammation induced Staphylococcus aureus toxins.
A central challenge of natural products research is assigning bioactive compounds from complex mixtures. The gold standard approach to address this challenge, bioassay-guided fractionation, often biased toward abundant, rather than bioactive, mixture components. This study evaluated the combination fractionation with untargeted metabolite profiling improve active component identification early in process. Key methodology was statistical modeling integrated biological and chemical data sets...
ABSTRACT Staphylococcus epidermidis is an opportunistic pathogen that one of the leading causes medical device infections. Global regulators like agr quorum-sensing system in this have received a limited amount attention, leaving important questions unanswered. There are three types S. strains, but only autoinducing peptide (AIP) signals has been identified (AIP-I), and cross talk between systems not tested. We structurally characterized all AIP using mass spectrometry discovered AIP-II...
Abstract The safety and efficacy of kratom (Mitragyna speciosa ) for treatment pain is highly controversial. Kratom produces more than 40 structurally related alkaloids, but most studies have focused on just two these, mitragynine 7-hydroxymitragynine. Here, we profiled 53 commercial products using untargeted LC–MS metabolomics, revealing distinct chemotypes that contain different levels the alkaloid speciofoline. Both were confirmed with DNA barcoding to be M. speciosa. To evaluate...
Two separate commercial products of kratom [Mitragyna speciosa (Korth.) Havil. Rubiaceae] were used to generate reference standards its indole and oxindole alkaloids. While has been studied for over a century, the characterization data in literature many alkaloids are either incomplete or inconsistent with modern standards. As such, full 1H 13C NMR spectra, along HRESIMS ECD data, reported 1–19. Of these, four new (7, 11, 17, 18) characterized using 2D absolute configurations 7, 18...
Human skin is home to a variety of commensal bacteria, including many species coagulase-negative staphylococci (CoNS). While it well established that the microbiota as whole maintains homeostasis and excludes pathogens (i.e., colonization resistance), relatively little known about unique contributions individual CoNS these interactions. Staphylococcus hominis second most frequently isolated from healthy skin, there emerging evidence suggest may play an important role in excluding pathogens,...
ABSTRACT The Staphylococcus aureus Agr system regulates virulence gene expression by responding to cell population density (quorum sensing). When an extracellular peptide signal (AIP-III in strain UAMS-1, used for these experiments) reaches a concentration threshold, the AgrC-AgrA two-component regulatory is activated through cascade of phosphorylation events, leading induction divergently transcribed agrBDCA operon and RNAIII gene. posttranscriptional regulator numerous metabolic...
ABSTRACT There has been major interest by the scientific community in antivirulence approaches against bacterial infections. However, partly due to a lack of viable lead compounds, therapeutics have yet reach clinic. Here we investigate development an targeting quorum sensing signal biosynthesis, process that is conserved Gram-positive pathogens. Some preliminary studies suggest small molecule ambuic acid biosynthesis inhibitor. To confirm this, constructed methicillin-resistant...
Recurrent epidemics of drug-resistant Staphylococcus aureus illustrate the rapid lapse antibiotic efficacy following clinical implementation. Over last decade, community-associated methicillin-resistant S. (MRSA) has emerged as a dominant cause infections, and this problem is amplified by hyper-virulent nature these isolates. Herein, we report discovery fungal metabolite, apicidin, an innovative means to counter both resistance virulence. Owing its breadth specificity quorum-sensing...
Recent studies highlight the abundance of commensal coagulase-negative staphylococci (CoNS) on healthy skin. Evidence suggests that CoNS actively shape skin immunological and microbial milieu to resist colonization or infection by opportunistic pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), in a variety mechanisms collectively termed resistance. One potential resistance mechanism is application quorum sensing, also called accessory gene regulator (agr) system, which...
Despite the value of mass spectrometry in modern natural products discovery workflows, it remains very difficult to compare data sets between laboratories. In this study we compared for same sample set from two different laboratories (quadrupole time-of-flight and quadrupole-Orbitrap) evaluated similarity these terms both features their ability describe chemical composition set. Somewhat surprisingly, sets, collected with appropriate controls replication, had low feature overlap (25.7%...
Mass spectrometry metabolomics has become increasingly popular as an integral aspect of studies to identify active compounds from natural product mixtures. Classical data analysis approaches do not consider the possibility that interactions (such synergy) could occur between mixture components. With this study, we developed "interaction metabolomics" overcome limitation. The innovation interaction is inclusion compound terms (CITs), which are calculated intensities each pair features...
The relative distribution of verapamil and its demethylated metabolite, norverapamil, was studied in rats at intervals after intraperitoneal injection the parent drug (30 mg/kg). This route administration simulated oral dosing, highest concentrations both unchanged metabolite were found liver, with lung kidney containing most remainder. rates disappearance from various organs followed first-order kinetics, rapid elimination occurred brain liver. In contrast, given intravenously to 3 dogs by...
The initial incursion of pandemic (H1N1) 2009 influenza A virus (pH1N1) into a European pig population is reported. Diagnosis swine caused by was made during September following routine submission samples for differential diagnosis causative agents respiratory disease, including virus. All four pigs (aged six weeks) submitted investigation from herd approximately 5000 animals in Northern Ireland, experiencing acute‐onset signs finishing and growing pigs, were positive immunofluorescence A....
Echinacea preparations, which are used for the prevention and treatment of upper respiratory infections, account 10% dietary supplement market in U.S., with sales totaling more than $100 million annually. In an attempt to shed light on Echinacea's mechanism action, we evaluated effects a 75% ethanolic root extract purpurea, prepared accord industry methods, cytokine chemokine production from RAW 264.7 macrophage-like cells. We found that displayed dual activities; could itself stimulate...
Bacterial efflux pumps are active transport proteins responsible for resistance to selected biocides and antibiotics. It has been shown that production of is up-regulated in a number highly pathogenic bacteria, including methicillin resistant Staphylococcus aureus. Thus, the identification new bacterial pump inhibitors topic great interest. Existing assays evaluate inhibitory activity rely on fluorescence by an substrate. When employing these plant extracts some purified compounds, we...
The development of a reverse transcriptase-polymerase chain reaction (RT-PCR) test for detecting chicken astroviruses (CAstV) is described. Primers, which amplified fragment 510 base pairs, were located in conserved regions within the ORF 1b (RNA polymerase) gene. limit detection was estimated to be approximately 60 viral copies using 10-fold dilution series vitro transcribed RNA. Positive signals produced with representative CAstV samples, some not detected by previously described RT-PCR...
The complete capsid gene sequences of 24 chicken astroviruses (CAstVs), collected in the UK, Germany, Netherlands and South Africa from 1980s to 2008, were determined compared with that a US CAstV (UGA-2006). Pairwise comparisons phylogenetic analysis demonstrated existence two major groups, designated A B, which shared 38 40% amino acid identity. CAstVs groups B protein identities ranging 26 38% other avian astroviruses. group comprised three subgroups, displayed inter-subgroup 77 82%,...
Many consumers are turning to kratom (Mitragyna speciosa) self-manage pain and opioid addiction. In the United States, an array of capsules, powders, loose-leaf products readily available. Additionally, several online sites supply live plants. A prerequisite establishing quality control assurance standards for industry, or understanding how alkaloid levels effect clinical outcomes, is identification quantitation major minor constituents within available preparations. To this end, ultra-high...
Managed honey bee colonies used for crop pollination are fed artificial diets to offset nutritional deficiencies related land-use intensification and climate change. In this study, we formulated novel microalgae using Chlorella vulgaris Arthrospira platensis (spirulina) biomass them young adult workers. Diet-induced changes in metabolite profiles were studied relative a natural pollen diet liquid chromatography-mass spectrometry (LC-MS) gas (GC-MS) metabolomics. Untargeted analyses of...