Medicine and Health Sciences Commons^™

Clinical Laboratory Testing Practices In Diffuse Gliomas Prior To Publication Of 2021 World Health Organization Classification Of Central Nervous System Tumors, Shakti H. Ramkissoon, Helen Fernandes, Dolores H. Lopez-Terrada, Meera R. Hameed, Dimitri G. Trembath, Julia A. Bridge, Neal I. Lindeman, Rhona J. Souers, Patricia Vasalos, Daniel J Brat, Joel T. Moncur

Journal Articles: Pathology and Microbiology

CONTEXT.—: Integration of molecular data into glioma classification supports diagnostic, prognostic, and therapeutic decision-making; however, testing practices for these informative biomarkers in clinical laboratories remain unclear.

OBJECTIVE.—: To examine the prevalence of molecular testing for clinically relevant biomarkers in adult and pediatric gliomas through review of a College of American Pathologists proficiency testing survey prior to the release of the 2021 World Health Organization Classification of Central Nervous System Tumors.

DESIGN.—: College of American Pathologists proficiency testing 2020 survey results from 96 laboratories performing molecular testing for diffuse gliomas were used to determine the use of testing for molecular biomarkers …

Staphylococcus Aureus Biofilms Induce Macrophage Dysfunction Through Leukocidin Ab And Alpha-Toxin., Tyler D. Scherr, Mark L. Hanke, Ouwen Huang, David B.A. James, Alexander R. Horswill, Kenneth W. Bayles, Paul D. Fey, Victor J. Torres, Tammy Kielian

Journal Articles: Pathology and Microbiology

UNLABELLED: The macrophage response to planktonic Staphylococcus aureus involves the induction of proinflammatory microbicidal activity. However, S. aureus biofilms can interfere with these responses in part by polarizing macrophages toward an anti-inflammatory profibrotic phenotype. Here we demonstrate that conditioned medium from mature S. aureus biofilms inhibited macrophage phagocytosis and induced cytotoxicity, suggesting the involvement of a secreted factor(s). Iterative testing found the active factor(s) to be proteinaceous and partially agr-dependent. Quantitative mass spectrometry identified alpha-toxin (Hla) and leukocidin AB (LukAB) as critical molecules secreted by S. aureus biofilms that inhibit murine macrophage phagocytosis and promote cytotoxicity. A role for Hla …

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 …

Ccpa Regulates Arginine Biosynthesis In Staphylococcus Aureus Through Repression Of Proline Catabolism., Austin S. Nuxoll, Steven M. Halouska, Marat Sadykov, Mark L. Hanke, Kenneth W. Bayles, Tammy Kielian, Robert Powers, Paul D. Fey

Journal Articles: Pathology and Microbiology

Staphylococcus aureus is a leading cause of community-associated and nosocomial infections. Imperative to the success of S. aureus is the ability to adapt and utilize nutrients that are readily available. Genomic sequencing suggests that S. aureus has the genes required for synthesis of all twenty amino acids. However, in vitro experimentation demonstrates that staphylococci have multiple amino acid auxotrophies, including arginine. Although S. aureus possesses the highly conserved anabolic pathway that synthesizes arginine via glutamate, we demonstrate here that inactivation of ccpA facilitates the synthesis of arginine via the urea cycle utilizing proline as a substrate. Mutations within putA, rocD, …

Contribution Of The Staphylococcus Aureus Atl Am And Gl Murein Hydrolase Activities In Cell Division, Autolysis, And Biofilm Formation., Jeffrey L. Bose, Mckenzie K. Lehman, Paul D. Fey, Kenneth W. Bayles

Journal Articles: Pathology and Microbiology

The most prominent murein hydrolase of Staphylococcus aureus, AtlA, is a bifunctional enzyme that undergoes proteolytic cleavage to yield two catalytically active proteins, an amidase (AM) and a glucosaminidase (GL). Although the bifunctional nature of AtlA has long been recognized, most studies have focused on the combined functions of this protein in cell wall metabolism and biofilm development. In this study, we generated mutant derivatives of the clinical S. aureus isolate, UAMS-1, in which one or both of the AM and GL domains of AtlA have been deleted. Examination of these strains revealed that each mutant exhibited growth rates comparable …

Nuclease Modulates Biofilm Formation In Community-Associated Methicillin-Resistant Staphylococcus Aureus., Megan R. Kiedrowski, Jeffrey S. Kavanaugh, Cheryl L. Malone, Joe M. Mootz, Jovanka M. Voyich, Mark S. Smeltzer, Kenneth W. Bayles, Alexander R. Horswill

Journal Articles: Pathology and Microbiology

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging contributor to biofilm-related infections. We recently reported that strains lacking sigma factor B (sigB) in the USA300 lineage of CA-MRSA are unable to develop a biofilm. Interestingly, when spent media from a USA300 sigB mutant was incubated with other S. aureus strains, biofilm formation was inhibited. Following fractionation and mass spectrometry analysis, the major anti-biofilm factor identified in the spent media was secreted thermonuclease (Nuc). Considering reports that extracellular DNA (eDNA) is an important component of the biofilm matrix, we investigated the regulation and role of Nuc in USA300. The expression of …

Epistatic Relationships Between Sara And Agr In Staphylococcus Aureus Biofilm Formation., Karen E. Beenken, Lara N. Mrak, Linda M. Griffin, Agnieszka K. Zielinska, Lindsey N. Shaw, Kelly C. Rice, Alexander R. Horswill, Kenneth W. Bayles, Mark S. Smeltzer

Journal Articles: Pathology and Microbiology

BACKGROUND: The accessory gene regulator (agr) and staphylococcal accessory regulator (sarA) play opposing roles in Staphylococcus aureus biofilm formation. There is mounting evidence to suggest that these opposing roles are therapeutically relevant in that mutation of agr results in increased biofilm formation and decreased antibiotic susceptibility while mutation of sarA has the opposite effect. To the extent that induction of agr or inhibition of sarA could potentially be used to limit biofilm formation, this makes it important to understand the epistatic relationships between these two loci.

METHODOLOGY/PRINCIPAL FINDINGS: We generated isogenic sarA and agr mutants in clinical isolates of S. …

Modulation Of Edna Release And Degradation Affects Staphylococcus Aureus Biofilm Maturation., Ethan E. Mann, Kelly C. Rice, Blaise R. Boles, Jennifer L. Endres, Dev Ranjit, Lakshmi Chandramohan, Laura H. Tsang, Mark S. Smeltzer, Alexander R. Horswill, Kenneth W. Bayles

Journal Articles: Pathology and Microbiology

Recent studies have demonstrated a role for Staphylococcus aureus cidA-mediated cell lysis and genomic DNA release in biofilm adherence. The current study extends these findings by examining both temporal and additional genetic factors involved in the control of genomic DNA release and degradation during biofilm maturation. Cell lysis and DNA release were found to be critical for biofilm attachment during the initial stages of development and the released DNA (eDNA) remained an important matrix component during biofilm maturation. This study also revealed that an lrgAB mutant exhibits increased biofilm adherence and matrix-associated eDNA consistent with its proposed role as an …