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Preparedness and response to chemical and biological threats: the role of exposure science.

Paul J. Lioy, Ph.D. - Mon, 10/16/2017 - 14:00

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Preparedness and response to chemical and biological threats: the role of exposure science.

Ann N Y Acad Sci. 2016 Aug;1378(1):108-117

Authors: Lioy PJ, Laskin JD, Georgopoulos PG

Abstract
There are multiple components to emergency preparedness and the response to chemical and biological threat agents. The 5Rs framework (rescue, reentry, recovery, restoration, and rehabitation) outlines opportunities to apply exposure science in emergency events. Exposure science provides guidance and refined tools for characterizing, assessing, and reducing risks from catastrophic events, such as the release of hazardous airborne chemicals or biological agents. Important challenges to be met include deployment of assets, including medications, before and after an emergency response situation. Assessment of past studies demonstrates the value of integrating exposure science methods into risk analysis and the management of catastrophic events.

PMID: 27479653 [PubMed - indexed for MEDLINE]

Categories: Publications from UCDPER Members

Diacetyl/l-Xylulose Reductase Mediates Chemical Redox Cycling in Lung Epithelial Cells.

Jeffrey D. Laskin, Ph.D. - Mon, 10/16/2017 - 14:00

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Diacetyl/l-Xylulose Reductase Mediates Chemical Redox Cycling in Lung Epithelial Cells.

Chem Res Toxicol. 2017 Jul 17;30(7):1406-1418

Authors: Yang S, Jan YH, Mishin V, Heck DE, Laskin DL, Laskin JD

Abstract
Reactive carbonyls such as diacetyl (2,3-butanedione) and 2,3-pentanedione in tobacco and many food and consumer products are known to cause severe respiratory diseases. Many of these chemicals are detoxified by carbonyl reductases in the lung, in particular, dicarbonyl/l-xylulose reductase (DCXR), a multifunctional enzyme important in glucose metabolism. DCXR is a member of the short-chain dehydrogenase/reductase (SDR) superfamily. Using recombinant human enzyme, we discovered that DCXR mediates redox cycling of a variety of quinones generating superoxide anion, hydrogen peroxide, and, in the presence of transition metals, hydroxyl radicals. Redox cycling activity preferentially utilized NADH as a cosubstrate and was greatest for 9,10-phenanthrenequinone and 1,2-naphthoquinone, followed by 1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone (menadione). Using 9,10-phenanthrenequinone as the substrate, quinone redox cycling was found to inhibit DCXR reduction of l-xylulose and diacetyl. Competitive inhibition of enzyme activity by the quinone was observed with respect to diacetyl (Ki = 190 μM) and l-xylulose (Ki = 940 μM). Abundant DCXR activity was identified in A549 lung epithelial cells when diacetyl was used as a substrate. Quinones inhibited reduction of this dicarbonyl, causing an accumulation of diacetyl in the cells and culture medium and a decrease in acetoin, the reduced product of diacetyl. The identification of DCXR as an enzyme activity mediating chemical redox cycling suggests that it may be important in generating cytotoxic reactive oxygen species in the lung. These activities, together with the inhibition of dicarbonyl/l-xylulose metabolism by redox-active chemicals, as well as consequent deficiencies in pentose metabolism, are likely to contribute to lung injury following exposure to dicarbonyls and quinones.

PMID: 28595002 [PubMed - indexed for MEDLINE]

Categories: Publications from UCDPER Members