Medical Microbiology Commons^™

Hemichannels In Neurodegenerative Diseases: Is There A Link To Pathology?, Megan Bosch, Tammy Kielian

Journal Articles: Pathology and Microbiology

Although originally considered a structural component of gap junctions, connexin hemichannels (HCs) are now recognized as functional entities capable of influencing metabolic gradients within the CNS, allowing direct communication between the intra- and extracellular milieus. Besides connexins, HCs can also be formed by pannexins, which are not capable of gap junction assembly. Both positive and negative effects have been attributed to HC activity in the context of neurodegenerative diseases. For example, HCs can exert neuroprotective effects by promoting the uptake of neurotoxic molecules, whereas chronic HC opening can disrupt molecular gradients leading to cellular dysfunction and death. The latter scenario …

Epoxide-Mediated Differential Packaging Of Cif And Other Virulence Factors Into Outer Membrane Vesicles, A. E. Ballok, L. M. Filkins, J.. M. Bomberger, B. A. Stanton, George A. O'Toole

Dartmouth Scholarship

Pseudomonas aeruginosa produces outer membrane vesicles (OMVs) that contain a number of secreted bacterial proteins, including phospholipases, alkaline phosphatase, and the CFTR inhibitory factor (Cif). Previously, Cif, an epoxide hydrolase, was shown to be regulated at the transcriptional level by epoxides, which serve as ligands of the repressor, CifR. Here, we tested whether epoxides have an effect on Cif levels in OMVs. We showed that growth of P. aeruginosa in the presence of specific epoxi

Clinical And Biochemical Function Of Polymorphic Nr0b1 Ggaa-Microsatellites In Ewing Sarcoma: A Report From The Children's Oncology Group., Michael J. Monument, Kirsten M. Johnson, Elizabeth Mcilvaine, Lisa Abegglen, W. Scott Watkins, Lynn B. Jorde, Richard B. Womer, Natalie Beeler, Laura Monovich, Elizabeth R. Lawlor, Julia A. Bridge, Joshua D. Schiffman, Mark D Krailo, R. Lor Randall, Stephen L. Lessnick

Journal Articles: Pathology and Microbiology

BACKGROUND: The genetics involved in Ewing sarcoma susceptibility and prognosis are poorly understood. EWS/FLI and related EWS/ETS chimeras upregulate numerous gene targets via promoter-based GGAA-microsatellite response elements. These microsatellites are highly polymorphic in humans, and preliminary evidence suggests EWS/FLI-mediated gene expression is highly dependent on the number of GGAA motifs within the microsatellite.

OBJECTIVES: Here we sought to examine the polymorphic spectrum of a GGAA-microsatellite within the NR0B1 promoter (a critical EWS/FLI target) in primary Ewing sarcoma tumors, and characterize how this polymorphism influences gene expression and clinical outcomes.

RESULTS: A complex, bimodal pattern of EWS/FLI-mediated gene expression was observed …

A Central Role For Carbon-Overflow Pathways In The Modulation Of Bacterial Cell Death., Vinai Chittezham Thomas, Marat Sadykov, Sujata S. Chaudhari, Joselyn Jones, Jennifer L. Endres, Todd J. Widhelm, Jong-Sam Ahn, Randeep S. Jawa, Matthew C. Zimmerman, Kenneth W. Bayles

Journal Articles: Pathology and Microbiology

Similar to developmental programs in eukaryotes, the death of a subpopulation of cells is thought to benefit bacterial biofilm development. However mechanisms that mediate a tight control over cell death are not clearly understood at the population level. Here we reveal that CidR dependent pyruvate oxidase (CidC) and α-acetolactate synthase/decarboxylase (AlsSD) overflow metabolic pathways, which are active during staphylococcal biofilm development, modulate cell death to achieve optimal biofilm biomass. Whereas acetate derived from CidC activity potentiates cell death in cells by a mechanism dependent on intracellular acidification and respiratory inhibition, AlsSD activity effectively counters CidC action by diverting carbon flux …

Immunomodulatory Activity Of Interferon-Beta, Lloyd H. Kasper, Anthony T. Reder

Dartmouth Scholarship

Multiple sclerosis (MS) is a complex disorder of the central nervous system that appears to be driven by a shift in immune functioning toward excess inflammation that results in demyelination and axonal loss. Beta interferons were the first class of disease-modifying therapies to be approved for patients with MS after treatment with this type I interferon improved the course of MS on both clinical and radiological measures in clinical trials. The mechanism of action of interferon-beta appears to be driven by influencing the immune system at many levels, including antigen-presenting cells, T cells, and B cells. One effect of these …

Characterizing The Response Of Multidrug-Resistant Klebsiella Pneumoniae Species To The Application Of A Phage Cocktail, Steven Liu

Symposium

Project Summary: The application of bacteriophages to treat bacterial infections is known as phage therapy, which takes advantage of bacteriophage’s natural ability to infect and lyse bacterial hosts. Phages have been shaped by billions of years of evolution to be highly specialized deliverers of bactericidal agents to the cytoplasm of their target bacteria. Ever since discovery of bacteriophages in 1915, phage therapy was recognized as a potentially powerful tool for eliminating bacterial infections. The effectiveness of phage therapy can be increased by creating a mixture of multiple phages to target a wider variety of bacterial strains. Furthermore, phage therapy has …

Human Antimicrobial Peptides And Proteins, Guangshun Wang

Journal Articles: Pathology and Microbiology

As the key components of innate immunity, human host defense antimicrobial peptides and proteins (AMPs) play a critical role in warding off invading microbial pathogens. In addition, AMPs can possess other biological functions such as apoptosis, wound healing, and immune modulation. This article provides an overview on the identification, activity, 3D structure, and mechanism of action of human AMPs selected from the antimicrobial peptide database. Over 100 such peptides have been identified from a variety of tissues and epithelial surfaces, including skin, eyes, ears, mouths, gut, immune, nervous and urinary systems. These peptides vary from 10 to 150 amino acids …

Avirulent Strains Of Toxoplasma Gondii Infect Macrophages By Active Invasion From The Phagosome, Yanlin Zhao, Andrew H. Marple, David J. P. Ferguson, David J. Bzik, George S. Yap

Dartmouth Scholarship

Unlike most intracellular pathogens that gain access into host cells through endocytic pathways, Toxoplasma gondii initiates infection at the cell surface by active penetration through a moving junction and subsequent formation of a parasitophorous vacuole. Here, we describe a noncanonical pathway for T. gondii infection of macrophages, in which parasites are initially internalized through phagocytosis, and then actively invade from within a phagosomal compartment to form a parasitophorous vacuole. This phagosome to vacuole invasion (PTVI) pathway may represent an intermediary link between the endocytic and the penetrative routes for host cell entry by intracellular pathogens. The PTVI pathway is preferentially …

Evidence For Aberrant Astrocyte Hemichannel Activity In Juvenile Neuronal Ceroid Lipofuscinosis (Jncl)., Maria Burkovetskaya, Nikolay Karpuk, Juan Xiong, Megan Bosch, Michael D. Boska, Hideyuki Takeuchi, Akio Suzumura, Tammy Kielian

Journal Articles: Pathology and Microbiology

Juvenile Neuronal Ceroid Lipofuscinosis (JNCL) is a lysosomal storage disease caused by an autosomal recessive mutation in CLN3 that leads to vision loss, progressive cognitive and motor decline, and premature death. Morphological evidence of astrocyte activation occurs early in the disease process and coincides with regions where neuronal loss eventually ensues. However, the consequences of CLN3 mutation on astrocyte function remain relatively ill-defined. Astrocytes play a critical role in CNS homeostasis, in part, by their ability to regulate the extracellular milieu via the formation of extensive syncytial networks coupled by gap junction (GJ) channels. In contrast, unopposed hemichannels (HCs) have …

A Novel Multivalent, Single-Domain Antibody Targeting Tcda And Tcdb Prevents Fulminant Clostridium Difficile Infection In Mice, Zhiyong Yang, Diane Schmidt, Weilong Liu, Shan Li, Lianfa Shi, Jinliang Sheng, Kevin Chen, Hua Yu, Jacqueline M. Tremblay, Xinhua Chen, Kurt H. Piepenbrink, Eric J. Sundberg, Ciaran P. Kelly, Guang Bai, Charles B. Shoemaker, Hanping Feng

Food for Health: Publications

The incidence of Clostridium difficile infection (CDI) and associated mortality have increased rapidly worldwide in recent years. Therefore, it is critical to develop new therapies for CDI. In this study, we generated a novel, potently neutralizing, tetravalent, and bispecific antibody composed of 2 heavy-chain-only V_H (V_HH) binding domains against both TcdA and TcdB (designated “ABA”) that reverses fulminant CDI in mice infected with an epidemic 027 strain after a single injection of the antibody. We demonstrated that ABA bound to both toxins simultaneously and displayed a significantly enhanced neutralizing activity both in vitro and in vivo. Additionally, …

Microbiota, Oral Microbiome, And Pancreatic Cancer, Dominique S. Michaud, Jacques Izard

Department of Food Science and Technology: Faculty Publications

Only 30% of patients diagnosed with pancreatic cancer survive one year post-diagnosis. Progress in understanding the causes of pancreatic cancer has been made, including solidifying the associations with obesity and diabetes, and a proportion of cases should be preventable through lifestyle modifications. Unfortunately, identifying reliable biomarkers of early pancreatic cancer has been extremely challenging, and no effective screening modality is currently available for this devastating form of cancer. Recent data suggest the microbiota may play a role in the disease process, but many questions remain. Future studies focusing on the human microbiome, both etiologically and as a marker of disease …

Functional Proteomic Analysis Reveals The Involvement Of Kiaa1199 In Breast Cancer Growth, Motility And Invasiveness., Mohammad-Saeid Jami, Jinxuan Hou, Miao Liu, M L. Varney, Hesham Hassan, Jixin Dong, Liying Geng, J. Wang, Fang Yu, Xin Huang, Hong Peng, Kai Fu, Yan Li, Rakesh Singh, Shi-Jian Ding

Journal Articles: Pathology and Microbiology

BACKGROUND: KIAA1199 is a recently identified novel gene that is up-regulated in human cancer with poor survival. Our proteomic study on signaling polarity in chemotactic cells revealed KIAA1199 as a novel protein target that may be involved in cellular chemotaxis and motility. In the present study, we examined the functional significance of KIAA1199 expression in breast cancer growth, motility and invasiveness.

METHODS: We validated the previous microarray observation by tissue microarray immunohistochemistry using a TMA slide containing 12 breast tumor tissue cores and 12 corresponding normal tissues. We performed the shRNA-mediated knockdown of KIAA1199 in MDA-MB-231 and HS578T cells to …

Autoantibodies To Agrin In Myasthenia Gravis Patients, Bin Zhang, Chengyong Shen, Beverly Bealmear, Samia Ragheb, Wen-Cheng Xiong, Richard A. Lewis, Robert P. Lisak, Lin Mei

Immunology and Microbiology Faculty Research Publications

To determine if patients with myasthenia gravis (MG) have antibodies to agrin, a proteoglycan released by motor neurons and is critical for neuromuscular junction (NMJ) formation, we collected serum samples from 93 patients with MG with known status of antibodies to acetylcholine receptor (AChR), muscle specific kinase (MuSK) and lipoprotein-related 4 (LRP4) and samples from control subjects (healthy individuals and individuals with other diseases). Sera were assayed for antibodies to agrin. We found antibodies to agrin in 7 serum samples of MG patients. None of the 25 healthy controls and none of the 55 control neurological patients had agrin antibodies. …

Systematic Analysis Of A Xenograft Mice Model For Kshv+ Primary Effusion Lymphoma (Pel), Lu Dai, Jimena Trillo-Tinoco, Lihua Bai, Baoli Kang, Zengguang Xu, Xiaofei Wen, Luis Del Valle, Zhiqiang Qin

School of Medicine Faculty Publications

Kaposi's sarcoma-associated herpesvirus is the causative agent of primary effusion lymphoma (PEL), which arises preferentially in the setting of infection with human immunodeficiency virus (HIV). Even with standard cytotoxic chemotherapy, PEL continues to cause high mortality rates, requiring the development of novel therapeutic strategies. PEL xenograft models employing immunodeficient mice have been used to study the in vivo effects of a variety of therapeutic approaches. However, it remains unclear whether these xenograft models entirely reflect clinical presentations of KSHV(+) PEL, especially given the recent description of extracavitary solid tumor variants arising in patients. In addition, effusion and solid tumor cells …

Hiding In Plain Sight: Interplay Between Staphylococcal Biofilms And Host Immunity., Tyler D. Scherr, Cortney E. Heim, John M. Morrison, Tammy Kielian

Journal Articles: Pathology and Microbiology

Staphylococcus aureus and Staphylococcus epidermidis are notable for their propensity to form biofilms on implanted medical devices. Staphylococcal biofilm infections are typified by their recalcitrance to antibiotics and ability to circumvent host immune-mediated clearance, resulting in the establishment of chronic infections that are often recurrent in nature. Indeed, the immunomodulatory lifestyle of biofilms seemingly shapes the host immune response to ensure biofilm engraftment and persistence in an immune competent host. Here, we provide a brief review of the mechanisms whereby S. aureus and S. epidermidis biofilms manipulate host-pathogen interactions and discuss the concept of microenvironment maintenance in infectious outcomes, as …

A Melanin-Independent Interaction Between Mc1r And Met Signalling Pathways Is Required For Hgf-Dependent Melanoma, Agnieszka Wolnicka-Głubisz, Faith M. Strickland, Albert Wielgus, Miriam Anver, Glenn Merlino, Edward C. De Fabo, Frances P. Noonan

Microbiology, Immunology, and Tropical Medicine Faculty Publications

Melanocortin 1 receptor (MC1R) signaling stimulates black eumelanin production through a cAMP-dependent pathway. MC1R polymorphisms can impair this process, resulting in a predominance of red phaeomelanin. The red hair, fair skin and UV sensitive phenotype is a well-described melanoma risk factor. MC1R polymorphisms also confer melanoma risk independent of pigment. We investigated the effect of Mc1r deficiency in a mouse model of UV-induced melanoma. C57BL/6-Mc1r+/+-HGF transgenic mice have a characteristic hyperpigmented black phenotype with extra-follicular dermal melanocytes located at the dermal/epidermal junction. UVB induces melanoma, independent of melanin pigmentation, but UVA-induced and spontaneous melanomas are dependent on black eumelanin. We …

Human And Helicobacter Pylori Coevolution Shapes The Risk Of Gastric Disease, Nuri Kodaman, Alvaro Pazos, Barbara G. Schneider, M. Blanca Piazuelo, Robertino Mera, Rafal S. Sobota

Dartmouth Scholarship

Helicobacter pylori is the principal cause of gastric cancer, the second leading cause of cancer mortality worldwide. However, H. pylori prevalence generally does not predict cancer incidence. To determine whether coevolution between host and pathogen influences disease risk, we examined the association between the severity of gastric lesions and patterns of genomic variation in matched human and H. pylori samples. Patients were recruited from two geographically distinct Colombian populations with significantly different incidences of gastric cancer, but virtually identical prevalence of H. pylori infection. All H. pylori isolates contained the genetic signatures of multiple ancestries, with an ancestral African cluster …

Response Of An Aggressive Periosteal Aneurysmal Bone Cyst (Abc) Of The Radius To Denosumab Therapy., Chantal Pauli, Bruno Fuchs, Christian Pfirrmann, Julia A. Bridge, Silvia Hofer, Beata Bode

Journal Articles: Pathology and Microbiology

Aneurysmal bone cyst (ABC), once considered a reactive lesion, has been proven to be a neoplasia characterized by rearrangements of the USP6-gene. Aggressive local growth and recurrences are common and therapeutic options may be limited due to the vicinity of crucial structures. We describe a case of a locally aggressive, multinucleated giant cell-containing lesion of the forearm of a 21-year old woman, treated with denosumab for recurrent, surgically uncontrollable disease. Under the influence of this RANKL inhibitor, the tumor showed a marked reduction of the content of the osteoclastic giant cells and an extensive metaplastic osteoid production leading to the …

Paracrine Apoptotic Effect Of P53 Mediated By Tumor Suppressor Par-4, Ravshan Burikhanov, Tripti Shrestha-Bhattarai, Nikhil Hebbar, Shirley Qiu, Yanming Zhao, Gerard P. Zambetti, Vivek M. Rangnekar

Radiation Medicine Faculty Publications

The guardian of the genome, p53, is often mutated in cancer and may contribute to therapeutic resistance. Given that p53 is intact and functional in normal tissues, we harnessed its potential to inhibit the growth of p53-deficient cancer cells. Specific activation of p53 in normal fibroblasts selectively induced apoptosis in p53-deficient cancer cells. This paracrine effect was mediated by p53-dependent secretion of the tumor suppressor Par-4. Accordingly, the activation of p53 in normal mice, but not p53⁻/⁻ or Par-4⁻/⁻ mice, caused systemic elevation of Par-4, which induced apoptosis of p53-deficient tumor cells. Mechanistically, p53 …

Antioxidants Condition Pleiotropic Vascular Responses To Exogenous H2o2: Role Of Modulation Of Vascular Tp Receptors And The Heme Oxygenase System, Nitin Puri, Fan Zhang, Sumit R. Monu, Komal R. Sodhi, Lars Bellner, Brian D. Lamon, Yilun Zhang, Nader G. Abraham, Alberto Nasjletti

Biochemistry and Microbiology

Aims: Hydrogen peroxide (H(2)O(2)), a nonradical oxidant, is employed to ascertain the role of redox mechanisms in regulation of vascular tone. Where both dilation and constriction have been reported, we examined the hypothesis that the ability of H(2)O(2) to effect vasoconstriction or dilation is conditioned by redox mechanisms and may be modulated by antioxidants.

Results: Exogenous H(2)O(2) (0.1-10.0 μM), dose-dependently reduced the internal diameter of rat renal interlobular and 3rd-order mesenteric arteries (p<0.05). This response was obliterated in arteries pretreated with antioxidants, including tempol, pegylated superoxide dismutase (PEG-SOD), butylated hydroxytoluene (BHT), and biliverdin (BV). However, as opposed to tempol or PEG-SOD, BHT & BV, antioxidants targeting radicals downstream of H(2)O(2), also uncovered vasodilation.

Innovations: Redox-dependent vasoconstriction to H(2)O(2) was blocked by inhibitors of cyclooxygenase (COX) (indomethacin-10 μM), thromboxane (TP) synthase (CGS13080-10 μM), and TP receptor antagonist (SQ29548-1 μM). However, H(2)O(2) …

Recruitment Of Tlr Adapter Trif To Tlr4 Signaling Complex Is Mediated By The Second Helical Region Of Trif Tir Domain, Wenji Piao, Lisa W. Ru, Kurt H. Piepenbrink, Eric J. Sundberg, Stefanie N. Vogel, Vladimir Y. Toshchakov

Food for Health: Publications

Toll/IL-1R resistance (TIR) domain–containing adapter-inducing IFN-β (TRIF) is a Toll-like receptor (TLR) adapter that mediates MyD88-independent induction of type I interferons through activation of IFN regulatory factor 3 and NFκB. We have examined peptides derived from the TRIF TIR domain for ability to inhibit TLR4. In addition to a previously identified BB loop peptide (TF4), a peptide derived from putative helix B of TRIF TIR (TF5) strongly inhibits LPS-induced cytokine and MAPK activation in wild-type cells. TF5 failed to inhibit LPS-induced cytokine and kinase activation in TRIF-deficient immortalized bone-marrow–derived macrophage, but was fully inhibitory in MyD88 knockout cells. TF5 does …

A Dysfunctional Tricarboxylic Acid Cycle Enhances Fitness Of Staphylococcus Epidermidis During Β-Lactam Stress., Vinai Chittezham Thomas, Lauren C. Kinkead, Ashley Janssen, Carolyn R. Schaeffer, Keith M. Woods, Jill K. Lindgren, Jonathan M. Peaster, Sujata S. Chaudhari, Marat Sadykov, Joselyn Jones, Sameh M. Mohamadi Abdelghani, Matthew C. Zimmerman, Kenneth W. Bayles, Greg A. Somerville, Paul D. Fey

Journal Articles: Pathology and Microbiology

A recent controversial hypothesis suggested that the bactericidal action of antibiotics is due to the generation of endogenous reactive oxygen species (ROS), a process requiring the citric acid cycle (tricarboxylic acid [TCA] cycle). To test this hypothesis, we assessed the ability of oxacillin to induce ROS production and cell death in Staphylococcus epidermidis strain 1457 and an isogenic citric acid cycle mutant. Our results confirm a contributory role for TCA-dependent ROS in enhancing susceptibility of S. epidermidis toward β-lactam antibiotics and also revealed a propensity for clinical isolates to accumulate TCA cycle dysfunctions presumably as a way to tolerate these …

Pouring Salt On A Wound: Pseudomonas Aeruginosa Virulence Factors Alter Na+ And Cl− Flux In The Lung, Alicia E. Ballok, George A. O'Toole

Dartmouth Scholarship

Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen with multiple niches in the human body, including the lung. P. aeruginosa infections are particularly damaging or fatal for patients with ventilator-associated pneumonia, chronic obstructive pulmonary disease, and cystic fibrosis (CF). To establish an infection, P. aeruginosa relies on a suite of virulence factors, including lipopolysaccharide, phospholipases, exoproteases, phenazines, outer membrane vesicles, type III secreted effectors, flagella, and pili. These factors not only damage the epithelial cell lining but also induce changes in cell physiology and function such as cell shape, membrane permeability, and protein synthesis. While such virulence factors are important in …

Methods For Quantifying T Cell Receptor Binding Affinities And Thermodynamics, Kurt H. Piepenbrink, Brian E. Gloor, Kathryn M. Armstrong, Brian M. Baker

Food for Health: Publications

αβ T cell receptors (TCRs) recognize peptide antigens bound and presented by class I or class II major histocompatibility complex (MHC) proteins. Recognition of a peptide/MHC complex is required for initiation and propagation of a cellular immune response, as well as the development and maintenance of the T cell repertoire. Here we discuss methods to quantify the affinities and thermodynamics of interactions between soluble ectodomains of TCRs and their peptide/MHC ligands, focusing on titration calorimetry, surface plasmon resonance, and fluorescence anisotropy. As TCRs typically bind ligand with weak-to-moderate affinities, we focus the discussion on means to enhance the accuracy and …

Database-Guided Discovery Of Potent Peptides To Combat Hiv-1 Or Superbugs., Guangshun Wang

Journal Articles: Pathology and Microbiology

Antimicrobial peptides (AMPs), small host defense proteins, are indispensable for the protection of multicellular organisms such as plants and animals from infection. The number of AMPs discovered per year increased steadily since the 1980s. Over 2,000 natural AMPs from bacteria, protozoa, fungi, plants, and animals have been registered into the antimicrobial peptide database (APD). The majority of these AMPs (>86%) possess 11-50 amino acids with a net charge from 0 to +7 and hydrophobic percentages between 31-70%. This article summarizes peptide discovery on the basis of the APD. The major methods are the linguistic model, database screening, de novo …

Anr And Its Activation By Plch Activity In Pseudomonas Aeruginosa Host Colonization And Virulence, Angelyca A. Jackson, Maegan J. Gross, Emily F. Daniels, Thomas H. Hampton, John H. Hammond, Isabelle Vallet-Gely, Simon L. Dove, Bruce A. Stanton, Deborah A. Hogan

Dartmouth Scholarship

Pseudomonas aeruginosa hemolytic phospholipase C (PlcH) degrades phosphatidylcholine (PC), an abundant lipid in cell membranes and lung surfactant. A ΔplcHR mutant, known to be defective in virulence in animal models, was less able to colonize epithelial cell monolayers and was defective in biofilm formation on plastic when grown in lung surfactant. Microarray analyses found that strains defective in PlcH production had lower levels of Anr-regulated transcripts than the wild type. PC degradation stimulated the Anr regulon in an Anr-dependent manner under conditions where Anr activity was submaximal because of the presence of oxygen. Two PC catabolites, choline and glycine …

Holobiont Nutrition: Considering The Role Of The Gastrointestinal Microbiota In The Health Benefits Of Whole Grains, Jens Walter, Ines Martinez, Devin J. Rose

Food for Health: Publications

Intake of whole grains and other food products high in dietary fiber have long been linked to the prevention of chronic diseases associated with inflammation. A contribution of the gastrointestinal microbiota to these effects has been suggested, but little is known on how whole grains interact with gut bacteria. We have recently published the first human trial that made use of next-generation sequencing to determine the effect of whole grains (whole grain barley, brown rice or a mixture of the two) on fecal microbiota structure and tested for associations between the gut microbiota and blood markers of inflammation, glucose and …

A Genetic Resource For Rapid And Comprehensive Phenotype Screening Of Nonessential Staphylococcus Aureus Genes., Paul D. Fey, Jennifer L. Endres, Vijaya Kumar Yajjala, Todd J. Widhelm, Robert J. Boissy, Jeffrey L. Bose, Kenneth W. Bayles

Journal Articles: Pathology and Microbiology

UNLABELLED: To enhance the research capabilities of investigators interested in Staphylococcus aureus, the Nebraska Center for Staphylococcal Research (CSR) has generated a sequence-defined transposon mutant library consisting of 1,952 strains, each containing a single mutation within a nonessential gene of the epidemic community-associated methicillin-resistant S. aureus (CA-MRSA) isolate USA300. To demonstrate the utility of this library for large-scale screening of phenotypic alterations, we spotted the library on indicator plates to assess hemolytic potential, protease production, pigmentation, and mannitol utilization. As expected, we identified many genes known to function in these processes, thus validating the utility of this approach. Importantly, we …

Molecular Mechanisms Related To Endotoxemia In Primary Human Cardiomyocytes In Culture, Atijah J. Collins

PCOM Biomedical Studies Student Scholarship

Cardiovascular disease (CVD) is the leading cause of death in the United States and has been for the past 80 years. Development of novel therapeutic agents to address the large number of CVD deaths requires an in depth understanding of the structural and functional properties of human cardiomyocytes. Over the last few years we have been developing an in vitro paradigm to assess molecular cardiodynamics in Primary Human Cardiomyocyte in culture (PHCC). We tested the hypothesis whether endotoxemia would exhibit a marked decrease in contractile proteins and cause apoptosis in PHCC. In the current series of experiments, we induced endotoxemia …

Characterization Of Brer Interaction With The Bile Response Promoters Breab And Brer In Vibrio Cholerae, Francisca A. Cerda-Maira, Gabriela Kovacikova, Brooke A. Jude, Karen Skorupski, Ronald Taylor

Dartmouth Scholarship

The Vibrio cholerae BreR protein is a transcriptional repressor of the breAB efflux system operon, which encodes proteins involved in bile resistance. In a previous study (F. A. Cerda-Maira, C. S. Ringelberg, and R. K. Taylor, J. Bacteriol. 190:7441-7452, 2008), we used gel mobility shift assays to determine that BreR binds at two independent binding sites at the breAB promoter and a single site at its own promoter. Here it is shown, by DNase I footprinting and site-directed mutagenesis, that BreR is able to bind at a distal and a proximal site in the breAB promoter. However, only one of …