Jeffrey J. Warren

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The prospects for using bacterial DNA as an intrinsic probe for HOCl and secondary oxidants/chlorinating agents associated with it has been evaluated using both in vitro and in vivo studies. Single-strand and double-strand breaks occurred in bare plasmid DNA that had been exposed to high levels of HOCl, although these reactions were very inefficient(More)
OBJECTIVES Missing laboratory data is a common issue, but the optimal method of imputation of missing values has not been determined. The aims of our study were to compare the accuracy of four imputation methods for missing completely at random laboratory data and to compare the effect of the imputed values on the accuracy of two clinical predictive models.(More)
Biological redox machines require efficient transfer of electrons and holes for function. Reactions involving multiple tunneling steps, termed "hopping," often promote charge separation within and between proteins that is essential for energy storage and conversion. Here we show how semiclassical electron transfer theory can be extended to include hopping(More)
HTML5 is being developed as the next major revision of HTML (Hypertext Markup Language), the core markup language of the World Wide Web. It aims at reducing the need for proprietary, plug-in-based rich Internet application (RIA) technologies such as Adobe Flash. The canvas element is part of HTML5 and is used to draw graphics using scripting (e.g.,(More)
We used Linear Genetic Programming (LGP) to study the extent to which automated learning techniques may be used to improve Unexploded Ordinance (UXO) discrimination from Protem-47 and Geonics EM61 non-invasive electromagnetic sensors. We conclude that: (1) Even after geophysicists have analyzed the EM61 signals and ranked anomalies in order of the(More)
We have investigated the kinetics of NO escape from Geobacillus stearothermophilus nitric oxide synthase (gsNOS). Previous work indicated that NO release was gated at position 223 in mammalian enzymes; our kinetics experiments include mutants at that position along with measurements on the wild type enzyme. Employing stopped-flow UV-vis methods, reactions(More)
Hydrogen atom transfer (HAT) reactions of the bis(histidine) cytochrome active site models (TPP)FeII(ImH)2 (FeIIImH) and (TPP)Fe(Im)(ImH) (FeIIIIm) have been examined in acetonitrile solvent (TPP = tetraphenylporphyrin, ImH = 4-methylimidazole). The ascorbate derivative 5,6-isopropylidine ascorbate, hydroquinone, and the hydroxylamine TEMPOH all rapidly add(More)
Redox reactions of tyrosine play key roles in many biological processes, including water oxidation and DNA synthesis. We first review the redox properties of tyrosine (and other phenols) in small molecules and related polypeptides, then report work on (H20)/(Y48)-modified Pseudomonas aeruginosa azurin. The crystal structure of this protein (1.18Å(More)
or since it forms a relatively weak O-H bond (aqueous BDFE(-OO-H) ) 81.6 kcal mol-1). The neutral perhydroxyl radical HO2 is a more reactive oxidant, in part because it forms a stronger O-H bond: E(HO2) ) 0.76 V and BDFEaq(HOO-H) ) 91.0 kcal mol-1 (Table 9). Thus, it is perhydroxyl, present in small quantities at biological pH (pKa HO2 ) 4.9),209 that is(More)
A heme model system has been developed in which the heme-propionate is the only proton donating/accepting site, using protoporphyrin IX-monomethyl esters (PPIX(MME)) and N-methylimidazole (MeIm). Proton-coupled electron transfer (PCET) reactions of these model compounds have been examined in acetonitrile solvent. (PPIX(MME))Fe(III)(MeIm)(2)-propionate(More)