Publications by authors named "Roland Liu"

The emergence of antibiotic-resistant bacteria (ARB) has necessitated the development of alternative therapies to deal with this global threat. Bacteriophages (viruses that target bacteria) that kill ARB are one such alternative. Although phages have been used clinically for decades with inconsistent results, a number of recent advances in phage selection, propagation, and purification have enabled a reevaluation of their utility in contemporary clinical medicine.

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The emergence of antibiotic resistant bacteria (ARB) has necessitated the development of alternative therapies to deal with this global threat. Bacteriophages (viruses that target bacteria) that kill ARB are one such alternative. While phages have been used clinically for decades with inconsistent results, a number of recent advances in phage selection, propagation and purification have enabled a reevaluation of their utility in contemporary clinical medicine.

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Background: The microbiome of the human gut serves a role in a number of physiological processes, but can be altered through effects of age, diet, and disturbances such as antibiotics. Several studies have demonstrated that commonly used antibiotics can have sustained impacts on the diversity and the composition of the gut microbiome. The impact of the two most overused antibiotics, azithromycin, and amoxicillin, in the human microbiome has not been thoroughly described.

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The gastrointestinal microbiome plays a significant role in modulating numerous host processes, including metabolism. Prior studies show that when mice receive fecal transplants from obese donors on high-fat diets (HFD) (even when recipient mice are fed normal diets after transplantation), they develop obese phenotypes, demonstrating the prominent role that gut microbiota play in determining lean and obese phenotypes. While much of the credit has been given to gut bacteria, the impact of gut viruses on these phenotypes is understudied.

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Background: The gastrointestinal microbiome plays a significant role in numerous host processes and has an especially large impact on modulating the host metabolism. Prior studies have shown that when mice receive fecal transplants from obese donors that were fed high-fat diets (HFD) (even when recipient mice are fed normal diets after transplantation), they develop obese phenotypes. These studies demonstrate the prominent role that the gut microbiota play in determining lean and obese phenotypes.

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The study of bacteriophage communities reproducing in the gastrointestinal tract is limited by the quality of model systems supporting experimental manipulation . Traditionally, studies aiming to experimentally address phage-bacteria dynamics have utilized gnotobiotic mice inoculated with defined bacterial communities. While mouse models simulate complex interactions between microbes and their host, they also forestall the study of phage-bacteria dynamics in isolation of host factors.

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Tests to diagnose acute SARS-CoV-2 infection are at the center of controlling the COVID-19 pandemic. Rapid tests benefit from providing quick results but suffer from lower sensitivity, while PCR tests usually take longer to provide more reliable results and can be difficult to scale to meet population needs. We evaluated the diagnostic efficacy of a Molecular Mirror assay (MMA) using nucleic acid extraction and a nucleic acid extraction-free method to determine its ability to identify SARS-CoV-2 in nasal specimens from individuals suspected of having SARS-CoV-2.

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Despite intensive research, the role of metabolism in bacterial sporulation remains poorly understood. Here, we demonstrate that sporulation entails a marked metabolic differentiation of the two cells comprising the sporangium: the forespore, which becomes the dormant spore, and the mother cell, which dies as sporulation completes. Our data provide evidence that metabolic precursor biosynthesis becomes restricted to the mother cell and that the forespore becomes reliant on mother cell-derived metabolites for protein synthesis.

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Microbial interactions are expected to be major determinants of microbiome structure and function. Although fungi are found in diverse microbiomes, their interactions with bacteria remain largely uncharacterized. In this work, we characterize interactions in 16 different bacterial-fungal pairs, examining the impacts of 8 different fungi isolated from cheese rind microbiomes on 2 bacteria (Escherichia coli and a cheese-isolated Pseudomonas psychrophila).

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Understanding the mechanism of action (MOA) of new antimicrobial agents is a critical step in drug discovery but is notoriously difficult for compounds that appear to inhibit multiple cellular pathways. We recently described image-based approaches [bacterial cytological profiling and rapid inducible profiling (RIP)] for identifying the cellular pathways targeted by antibiotics. Here we have applied these methods to examine the effects of proteolytically degrading enzymes involved in pyrimidine nucleotide biosynthesis, a pathway that produces intermediates for transcription, DNA replication, and cell envelope synthesis.

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Objectives: The role of protease-activated receptor 1 (PAR1) in the pathogenesis of pneumonia and sepsis is ambiguous given the existing literature. As PAR1 is classically activated by the coagulation-based protease thrombin and leads to vascular leakage, our hypothesis was that PAR1 blockade with SCH79797 would be therapeutically beneficial in an experimental model of murine Gram-negative pneumonia.

Methods: In this study, we administered SCH79797 via the intrapulmonary route 6 h after the establishment of Escherichia coli pneumonia and observed a significant improvement in survival, lung injury, bacterial clearance and inflammation.

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