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Dallas, TX, United States

Chai W.,Southern Methodist University | Nguyen E.,Hockaday School | Doran J.,Southern Methodist University | Han K.,Coppell High School | And 7 more authors.
Tetrahedron Letters

The di-tert-butyl-di-p-nitrophenyl ester of hydrazinetetracarboxylic acid was prepared and shown to be useful in the preparation of urazoles (i.e., 1,2,4-triazolidine-3,5-diones), by reaction with a primary amine using either n-BuLi or pyridine as base, depending on the desired N4 substituent. With more electronegative N4 substituents, pyridine is the preferred base. This work complements our reported urazole synthesis, which introduced the N4 substituent early in the sequence and thus did not facilitate variation at N4 for library synthesis. © 2013 Elsevier Ltd. All rights reserved. Source

Shin Y.J.,Pusan National University | Kim J.J.,Groton School | Kim Y.J.,Hockaday School | Kim W.H.,Sehwa High School | And 8 more authors.
Journal of Medicinal Food

Mercury is a well-known environmental pollutant that can cause nephropathic diseases, including acute kidney injury (AKI). Although quercetin (QC), a natural flavonoid, has been reported to have medicinal properties, its potential protective effects against mercury-induced AKI have not been evaluated. In this study, the protective effect of QC against mercury-induced AKI was investigated using biochemical parameters, new protein-based urinary biomarkers, and a histopathological approach. A 250 mg/kg dose of QC was administered orally to Sprague-Dawley male rats for 3 days before administration of mercury chloride (HgCl2). All animals were sacrificed at 24 h after HgCl2 treatment, and biomarkers associated with nephrotoxicity were measured. Our data showed that QC absolutely prevented HgCl2-induced AKI, as indicated by biochemical parameters such as blood urea nitrogen (BUN) and serum creatinine (sCr). In particular, QC markedly decreased the accumulation of Hg in the kidney. Urinary excretion of protein-based biomarkers, including clusterin, kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), monocyte chemoattractant protein-1 (MCP-1), tissue inhibitor of metalloproteinases 1 (TIMP-1), and vascular endothelial growth factor (VEGF) in response to HgCl2 administration were significantly decreased by QC pretreatment relative to that in the HgCl2-treated group. Furthermore, urinary excretion of metallothionein and Hg were significantly elevated by QC pretreatment. Histopathological examination indicated that QC protected against HgCl2-induced proximal tubular damage in the kidney. A TUNEL assay indicated that QC pretreatment significantly reduced apoptotic cell death in the kidney. The administration of QC provided significant protective effects against mercury-induced AKI. © Mary Ann Liebert, Inc. and Korean Society of Food Science and Nutrition 2015. Source

Cao J.,Southern Methodist University | Lopez R.,Southwestern Medical Center | Thacker J.M.,Southern Methodist University | Moon J.Y.,Southern Methodist University | And 6 more authors.
Chemical Science

Hydrogen sulphide (H2S) is an endogenous mediator of human health and disease, but precise measurement in living cells and animals remains a considerable challenge. We report the total chemical synthesis and characterization of three 1,2-dioxetane chemiluminescent reaction-based H2S probes, CHS-1, CHS-2, and CHS-3. Upon treatment with H2S at physiological pH, these probes display instantaneous light emission that is sustained for over an hour with high selectivity against other reactive sulphur, oxygen, and nitrogen species. Analysis of the phenol/phenolate equilibrium and atomic charges has provided a generally applicable predictive model to design improved chemiluminescent probes. The utility of these chemiluminescent reagents was demonstrated by applying CHS-3 to detect cellularly generated H2S using a multi-well plate reader and to image H2S in living mice using CCD camera technology. © The Royal Society of Chemistry 2015. Source

Nguyen T.Q.,Southern Methodist University | Chai W.,Southern Methodist University | Gu J.,Hockaday School | Cook K.,University of Texas at Austin | And 11 more authors.
Tetrahedron Letters

A diastereoselective process for the formation of intermediates suitable for the preparation of C1 substituted carbapenems was developed. The process is readily scalable and does not involve organometallics or strong bases such as LDA. © 2015 Elsevier Ltd.All rights reserved. Source

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