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Full-Text Articles in Medicine and Health Sciences

Monocyte Anti-Inflammatory Activity Is Dictated By Metabolic Status During Staphylococcus Aureus Biofilm Infection, Kelsey J. Yamada May 2019

Monocyte Anti-Inflammatory Activity Is Dictated By Metabolic Status During Staphylococcus Aureus Biofilm Infection, Kelsey J. Yamada

Theses & Dissertations

Staphylococcus aureus biofilms represent a significant cause of morbidity and economic burden and are often associated with nosocomial infections, including medically implanted devices. In particular, prosthetic joint infections (PJIs) are a growing concern due to the continued increase in orthopedic procedures. Staphylococcal species cause >50% of all PJIs, while S. aureus represents the most invasive and associated with the most morbidity. S. aureus-associated biofilm infections are recalcitrant to antibiotic therapy, due to both the acquisition of genetic elements and metabolic dormancy. Furthermore, S. aureus biofilm infections remain chronic because they cannot be cleared by the immune system. Recent studies …


Reanalysis Of The Nccn Pd-L1 Companion Diagnostic Assay Study For Lung Cancer In The Context Of Pd-L1 Expression Findings In Triple-Negative Breast Cancer, David L. Rimm, Gang Han, Janis M. Taube, Eunhee S. Yi, Julia A. Bridge, Douglas B. Flieder, Robert Homer, Anja C. Roden, Fred R. Hirsch, Ignacio I. Wistuba, Lajos Pusztai Jan 2019

Reanalysis Of The Nccn Pd-L1 Companion Diagnostic Assay Study For Lung Cancer In The Context Of Pd-L1 Expression Findings In Triple-Negative Breast Cancer, David L. Rimm, Gang Han, Janis M. Taube, Eunhee S. Yi, Julia A. Bridge, Douglas B. Flieder, Robert Homer, Anja C. Roden, Fred R. Hirsch, Ignacio I. Wistuba, Lajos Pusztai

Journal Articles: Pathology and Microbiology

The companion diagnostic test for checkpoint inhibitor immune therapy is an immunohistochemical test for PD-L1. The test has been shown to be reproducible for expression in tumor cells, but not in immune cells. Immune cells were used in the IMpassion130 trial which showed PD-L1 expression was associated with a better outcome. Two large studies have been done assessing immune cell PD-L1 expression in lung cancer. Here, we reanalyze one of those studies, to show that, even with an easier scoring method, there is still only poor agreement between assays and pathologist for immune cell PD-L1 expression.


Observations Of Shear Stress Effects On Staphylococcus Aureus Biofilm Formation, Erica Sherman, Kenneth W. Bayles, Derek E. Moormeier, Jennifer L. Endres, Timothy Wei Jan 2019

Observations Of Shear Stress Effects On Staphylococcus Aureus Biofilm Formation, Erica Sherman, Kenneth W. Bayles, Derek E. Moormeier, Jennifer L. Endres, Timothy Wei

Journal Articles: Pathology and Microbiology

Staphylococcus aureus bacteria form biofilms and distinctive microcolony or "tower" structures that facilitate their ability to tolerate antibiotic treatment and to spread within the human body. The formation of microcolonies, which break off, get carried downstream, and serve to initiate biofilms in other parts of the body, is of particular interest here. It is known that flow conditions play a role in the development, dispersion, and propagation of biofilms in general. The influence of flow on microcolony formation and, ultimately, what factors lead to microcolony development are, however, not well understood. The hypothesis being examined is that microcolony structures form …


Urease Is An Essential Component Of The Acid Response Network Of Staphylococcus Aureus And Is Required For A Persistent Murine Kidney Infection, Chunyi Zhou, Fatema Bhinderwala, Mckenzie K. Lehman, Vinai Chittezham Thomas, Sujata S. Chaudhari, Kelsey J. Yamada, Kirk W. Foster, Robert Powers, Tammy Kielian, Paul D. Fey Jan 2019

Urease Is An Essential Component Of The Acid Response Network Of Staphylococcus Aureus And Is Required For A Persistent Murine Kidney Infection, Chunyi Zhou, Fatema Bhinderwala, Mckenzie K. Lehman, Vinai Chittezham Thomas, Sujata S. Chaudhari, Kelsey J. Yamada, Kirk W. Foster, Robert Powers, Tammy Kielian, Paul D. Fey

Journal Articles: Pathology and Microbiology

Staphylococcus aureus causes acute and chronic infections resulting in significant morbidity. Urease, an enzyme that generates NH3 and CO2 from urea, is key to pH homeostasis in bacterial pathogens under acidic stress and nitrogen limitation. However, the function of urease in S. aureus niche colonization and nitrogen metabolism has not been extensively studied. We discovered that urease is essential for pH homeostasis and viability in urea-rich environments under weak acid stress. The regulation of urease transcription by CcpA, Agr, and CodY was identified in this study, implying a complex network that controls urease expression in response to changes in metabolic …


Protease-Mediated Growth Of Staphylococcus Aureus On Host Proteins Is Opp3 Dependent, Mckenzie K. Lehman, Austin S. Nuxoll, Kelsey J. Yamada, Tammy Kielian, Steven D. Carson, Paul D. Fey Jan 2019

Protease-Mediated Growth Of Staphylococcus Aureus On Host Proteins Is Opp3 Dependent, Mckenzie K. Lehman, Austin S. Nuxoll, Kelsey J. Yamada, Tammy Kielian, Steven D. Carson, Paul D. Fey

Journal Articles: Pathology and Microbiology

Staphylococcus aureus has the ability to cause infections in multiple organ systems, suggesting an ability to rapidly adapt to changing carbon and nitrogen sources. Although there is little information about the nutrients available at specific sites of infection, a mature skin abscess has been characterized as glucose depleted, indicating that peptides and free amino acids are an important source of nutrients for the bacteria. Our studies have found that mutations in enzymes necessary for growth on amino acids, including pyruvate carboxykinase (ΔpckA) and glutamate dehydrogenase (ΔgudB), reduced the ability of the bacteria to proliferate within a …


Identification Of Extracellular Dna-Binding Proteins In The Biofilm Matrix., Jeffrey S. Kavanaugh, Caralyn E. Flack, Jessica Lister, Erica B. Ricker, Carolyn B. Ibberson, Christian Jenul, Derek E. Moormeier, Elizabeth A. Delmain, Kenneth W. Bayles, Alexander R. Horswill Jan 2019

Identification Of Extracellular Dna-Binding Proteins In The Biofilm Matrix., Jeffrey S. Kavanaugh, Caralyn E. Flack, Jessica Lister, Erica B. Ricker, Carolyn B. Ibberson, Christian Jenul, Derek E. Moormeier, Elizabeth A. Delmain, Kenneth W. Bayles, Alexander R. Horswill

Journal Articles: Pathology and Microbiology

We developed a new approach that couples Southwestern blotting and mass spectrometry to discover proteins that bind extracellular DNA (eDNA) in bacterial biofilms. Using Staphylococcus aureus as a model pathogen, we identified proteins with known DNA-binding activity and uncovered a series of lipoproteins with previously unrecognized DNA-binding activity. We demonstrated that expression of these lipoproteins results in an eDNA-dependent biofilm enhancement. Additionally, we found that while deletion of lipoproteins had a minimal impact on biofilm accumulation, these lipoprotein mutations increased biofilm porosity, suggesting that lipoproteins and their associated interactions contribute to biofilm structure. For one of the lipoproteins, SaeP, we …