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Jeon, J. H.

Publications and source records attributed to Jeon, J. H..

2 recordsLinked to original sources

Acute characterization of tissue and functional deficits in a clinically translatable pig model of ischemic stroke

The acute stroke phase is a critical time frame used to evaluate stroke severity, therapeutic options, and prognosis while also serving as a major target for the development of diagnostics. To better understand stroke pathophysiology and to enhance the development of treatments, our group developed a translational pig ischemic stroke model. In this study, the evolution of acute ischemic stroke tissue damage, immune response, and functional deficits were further characterized in the pig model. Stroke was induced by middle cerebral artery occlusion in Landrace pigs. At 24 hours post-stroke, magnetic resonance imaging revealed a decrease in ipsilateral diffusivity and an increase in hemispheric swelling and intracranial hemorrhage resulting in notable midline shift. Stroke negatively impacted white matter integrity leading to decreased fractional anisotropy. Similar to acute clinical patients, stroked pigs showed a reduction in circulating lymphocytes and a surge in neutrophils and band cells. Functional responses corresponded with structural changes with reduced exploration in open field testing and impairments in spatiotemporal gait parameters. This novel, acute ischemia characterization provides important insights into tissue and functional level changes in a pig model that can be used to identify treatment targets and future testing of therapeutics and diagnostics.

neuroscience

Dual activity of PNGM-1, a metallo-β-lactamase and tRNase Z, pinpoints the evolutionary origin of subclass B3 metallo-β-lactamases

Antibiotic resistance is a steadily increasing global problem which could lead to a fundamental upheaval in clinical care with the potential to return us to the pre-antibiotic era1-4. The production of {beta}-lactamases, a group of enzymes that confer antibiotic resistance in Gram-negative bacteria, is now one of the major barriers in treating Gram-negative infections5. {beta}-Lactamases are classified according to their catalytic mechanisms into serine {beta}-lactamases and metallo-{beta}-lactamases6,7. There are functional and structural similarities between serine {beta}-lactamases and penicillin-binding proteins, and so serine {beta}-lactamases are thought to have evolved from a penicillin-binding protein7,8. Given the functional and structural differences between serine {beta}-lactamases and metallo-{beta}-lactamases, metallo-{beta}-lactamases are thought to have evolved from a protein other than a penicillin-binding protein, but to date this ancestor remains unknown8-11. We discovered PNGM-1, the first subclass B3 metallo-{beta}-lactamase, in deep-sea sediments that predate the antibiotic era12. Here we discover the dual activity of PNGM-1, pinpointing the evolutionary origin of subclass B3 metallo-{beta}-lactamases. Phylogenetic analysis suggested that PNGM-1 could yield insights into the evolutionary origin of subclass B3 metallo-{beta}-lactamases. We reveal the structural similarities between tRNase Zs and PNGM-1, which prompted us to investigate their evolutionary relationship and the possibility of them possessing dual enzymatic activities. We demonstrate that PNGM-1 has dual activity with both true metallo-{beta}-lactamase and tRNase Z activity, suggesting that PNGM-1 is thought to have evolved from a tRNase Z. We also show kinetic and structural comparisons between PNGM-1 and other proteins including subclass B3 metallo-{beta}-lactamases and tRNase Zs. These comparisons revealed that the B3 metallo-{beta}-lactamase activity of PNGM-1 is a promiscuous activity and subclass B3 metallo-{beta}-lactamases are thought to have evolved through PNGM-1 activity. Our work provides a foundation for the evolution of tRNase Z into subclass B3 metallo-{beta}-lactamases through the dual activity of PNGM-1.

microbiology