Allan J. McKinley

Specific dietary polyphenols attenuate atherosclerosis in apolipoprotein E-knockout mice by alleviating inflammation and endothelial dysfunction.

Objective—Animal and clinical studies have suggested that polyphenols in fruits, red wine, and tea may delay the development of atherosclerosis through their antioxidant and anti-inflammatory properties. We investigated whether individual dietary polyphenols representing different polyphenolic classes, namely quercetin (flavonol), (−)-epicatechin (flavan-3-ol), theaflavin (dimeric catechin), sesamin (lignan), or chlorogenic acid (phenolic acid), reduce atherosclerotic lesion formation in the apolipoprotein E (ApoE)−/− gene–knockout mouse. Methods and Results—Quercetin and theaflavin (64-mg/kg body mass daily) significantly attenuated atherosclerotic lesion size in the aortic sinus and thoracic aorta (P<0.05 versus ApoE−/− control mice). Quercetin significantly reduced aortic F2-isoprostane, vascular superoxide, vascular leukotriene B4, and plasma-sP-selectin concentrations; and augmented vascular endothelial NO synthase activity, heme oxygenase-1 protein, and urinary nitrate excretion (P<0.05 versus control ApoE−/− mice). Theaflavin showed similar, although less extensive, significant effects. Although (−)-epicatechin significantly reduced F2-isoprostane, superoxide, and endothelin-1 production (P<0.05 versus control ApoE−/− mice), it had no significant effect on lesion size. Sesamin and chlorogenic acid treatments exerted no significant effects. Quercetin, but not (−)-epicatechin, significantly increased the expression of heme oxygenase-1 protein in lesions versus ApoE−/− controls. Conclusion—Specific dietary polyphenols, in particular quercetin and theaflavin, may attenuate atherosclerosis in ApoE−/− gene–knockout mice by alleviating inflammation, improving NO bioavailability, and inducing heme oxygenase-1. These data suggest that the cardiovascular protection associated with diets rich in fruits, vegetables, and some beverages may in part be the result of flavonoids, such as quercetin.

Mechanochemical synthesis of nanocrystalline SnO2–ZnO photocatalysts

Mechanochemical processing of anhydrous chloride precursors with Na2CO3 has been investigated as a means of manufacturing nanocrystalline SnO2 doped ZnO photocatalysts. High-energy milling and heat-treatment of a 0.1SnCl2+0.9ZnCl2+Na2CO3+4NaCl reactant mixture was found to result in the formation of a composite powder consisting of oxide grains embedded within a matrix of NaCl. Subsequent washing with deionized water resulted in removal of the NaCl matrix phase and partial hydration of the oxide reaction product with the consequent formation of ZnSn(OH)6. The extent of this hydration reaction was found to decrease in a linear fashion with the temperature of the post-milling heat-treatment over the range of 400–700 °C. For a heat-treatment temperature of 700 °C, the SnO2 doped ZnO powder was found to exhibit significantly higher photocatalytic activity than either single-phase SnO2 or ZnO powders that were synthesized using similar processing conditions. The heightened photocatalytic activity of the SnO2 doped ZnO was attributed to its higher specific surface area and the enhanced charge separation arising from the coupling of ZnO with SnO2.

The Production of Oxidants in Europa's Surface

The oxidants produced by radiolysis and photolysis in the icy surface of Europa may be necessary to sustain carbon-based biochemistry in Europas putative subsurface ocean. Because the subduction of oxidants to the ocean presents considerable thermodynamic challenges, we examine the formation of oxygen and related species in Europas surface ice with the goal of characterizing the chemical state of the irradiated material. Relevant spectral observations of Europa and the laboratory data on the production of oxygen and related species are first summarized. Since the laboratory data are incomplete, we examine the rate equations for formation of oxygen and its chemical precursors by radiolysis and photolysis. Measurements and simple rate equations are suggested that can be used to characterize the production of oxidants in Europas surface material and the chemical environment produced by radiolysis. Possible precursor molecules and the role of radical trapping are examined. The possibility of oxygen reactions on grain surfaces in Europas regolith is discussed, and the earlier estimates of the supply of O(2) to the atmosphere are increased.

Solution photochemistry of poly(dialkylsilanes): a new class of photoresists

polysilanes r epresent a new class of polymeric materials of considerable theoretical and practical i nterest. Although formally saturated, they absorb in the near UV and undergo rapid photodegradation . After a review of the present understanding of the e lectronic structure of poly(dialkylsi1a nes) as a function of backbone conformation, we summarize their photophysics and describe recent advances in the understanding of their solution

A Metabolite Profiling Approach to Identify Biomarkers of Flavonoid Intake in Humans

Flavonoids are phytochemicals that are widespread in the human diet. Despite limitations in their bioavailability, experimental and epidemiological data suggest health benefits of flavonoid consumption. Valid biomarkers of flavonoid intake may be useful for estimating exposure in a range of settings. However, to date, few useful flavonoid biomarkers have been identified. In this study, we used a metabolite profiling approach to examine the aromatic and phenolic profile of plasma and urine of healthy men after oral consumption of 200 mg of the pure flavonoids, quercetin, (-)-epicatechin, and epigallocatechin gallate, which represent major flavonoid constituents in the diet. Following enzymatic hydrolysis, 71 aromatic compounds were quantified in plasma and urine at 2 and 5 h, respectively, after flavonoid ingestion. Plasma concentrations of different aromatic compounds ranged widely, from 0.01 to 10 micromol/L, with variation among volunteers. None of the aromatic compounds was significantly elevated in plasma 2 h after consumption of either flavonoid compared with water placebo. This indicates that flavonoid-derived aromatic compounds are not responsible for the acute physiological effects reported within 2 h in previous human intervention studies involving flavonoids or flavonoid-rich food consumption. These effects are more likely due to absorption of the intact flavonoid. Our urine analysis suggested that urinary 4-ethylphenol, benzoic acid, and 4-ethylbenzoic acid may be potential biomarkers of quercetin intake and 1,3,5-trimethoxybenzene, 4-O-methylgallic acid, 3-O-methylgallic acid, and gallic acid may be potential markers of epigallocatechin gallate intake. Potential biomarkers of (-)-epicatechin were not identified. These urinary biomarkers may provide an accurate indication of flavonoid exposure.

Benzotriazoles in the Aquatic Environment: a Review of Their Occurrence, Toxicity, Degradation and Analysis

Benzotriazoles (BTs) are an emerging class of environmental pollutants used in a wide range of industrial applications. Benzotriazole (BTri) and 5-methylbenzotriazole (5-MeBT) have recently been detected in water supplies around the world, and are thus attracting the attention of many environmental researchers. The focus of this review is on assessing contemporary methods to detect BTs using high-performance liquid chromatography (HPLC), and providing information regarding their occurrence, degradation and toxicity within the environment.

A fast liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) method for the identification of organic explosives and propellants.

A fast, highly specific and sensitive method for the detection of an extensive list of organic explosives and propellants using an optimised Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry (LC-QToF-MS) procedure has been developed. Analyte specific information including retention time, adduct accurate mass and fragmentation data was firstly collected using both positive and negative ion Atmospheric Pressure Chemical Ionisation (APCI) and entered into a Personal Compound Database/Library (PCDL). The custom PCDL can then be used to screen any sample for the presence of organic explosives and propellants, generating a match score for any identified compounds. To date over 50 organic explosives and propellants have been characterised and entered into the database representing those likely to be encountered in forensic and environmental samples and also a range of specialist explosives.

The role of the periplasmic loop residue glutamine 65 for MscL mechanosensitivity

The periplasmic loop of MscL, the mechanosensitive channel of large conductance, acts as a spring resisting the opening of the channel. Recently, a high-throughput functional screening of a range of MscL structural mutants indicated that the substitution of residue glutamine (Q) 65 with arginine (R) or leucine (L) leads to a wild-type (WT)-like and a loss-of-function (LOF) phenotype, respectively (Maurer and Dougherty J. Biol. Chem. 278(23):21076–21082, 2003). We used electron paramagnetic resonance (EPR) spectroscopy, single-channel recording and in vivo experiments to investigate further the effect of R and L mutation of Q65 on the gating mechanism of MscL. Structural analysis of Q65R and Q65L was carried out by coupling the site-directed spin labeling (SDSL) with EPR spectroscopy. A SDSL cysteine mutant of the isoleucine 24 residue (I24C-SL) in the first transmembrane domain, TM1, of MscL served as a reporter residue in EPR experiments. This was due to its strong spin–spin interaction with the neighboring I24C-SL residues in the MscL channel pentamer (Perozo et al.Nature 418:942–948, 2002). The effects of bilayer incorporation of lysophosphatidylcholine on the MscL mutants were also investigated. Functional analysis was carried out using patch-clamp recordings from these mutants and WT MscL reconstituted into artificial liposomes. Although our data are largely in agreement with the high-throughput mutational analysis of Maurer and Dougherty, this study shows that Q65R and Q65L form functional channels and that these mutations lead to partial gain-of-function (GOF) and LOF mutation, respectively. Overall, our study confirms and advances the notion that the periplasmic loop plays a role in setting the channel mechanosensitivity.

Electron spin resonance and theoretical studies of the PO2 and AsO2 radicals in neon matrices at 4 K: Laser vaporization and x‐irradiation radical generation techniques

The utilization of high energy generation techniques for trapping ion radicals and other reactive intermediates in neon matrices at 4 K is discussed. Electron spin resonance (ESR) results for several small radicals are presented to demonstrate the application of x irradiation and reactive laser vaporization for neon matrix isolation studies. Detailed ESR studies of the PO2 and AsO2 radicals, along with ab initio theoretical computations of their nuclear hyperfine interactions, are presented. No previous ESR observations have been reported for these radicals, although PO2 has been studied under high resolution in the gas phase utilizing far‐infrared laser magnetic resonance and microwave spectroscopies.

A comparison of common swabbing materials for the recovery of organic and inorganic explosive residues.

The efficiency of solvent based extraction methods used to remove explosive residues from four different swab types was investigated. Known amounts of organic and inorganic residues were spiked onto a swab surface with acetonitrile or ethanol:water combined with ultrasonication or physical manipulation used to extract the residues from each swab. The efficiency of each procedure was then calculated using liquid chromatography‐ultraviolet detection for organic residues and ion chromatography for inorganic residues. Results indicated that acetonitrile combined with physical agitation proved to be the most efficient method; returning analyte recoveries c. 95% for both alcohol based swabs and cotton balls. Inorganic residues were efficiently extracted using ethanol:water, while the use of acetonitrile followed by water significantly reduced the recovery of inorganic residues. Swab storage conditions were then investigated with results indicating decreased storage temperatures are required to retain the more volatile explosives.