Ambient air measurement of acrolein and other carbonyls at the Oakland-San Francisco Bay Bridge toll plaza

Interest in ambient concentrations of acrolein and other alpha,beta-unsaturated aldehydes and dicarbonyls (e.g., crotonaldehyde, methyl glyoxal, glyoxal, malonaldehyde (malondialdehyde)) is growing because either they exist at high levels in motor vehicle emissions or they arise from photooxidation of other hydrocarbons emitted from mobile sources. In addition, their mutagenic, genotoxic, or carcinogenic properties are well-established, and the results of a dispersion-modeling study regarding the health risks posed by the 188 hazardous air pollutants in California attributes the highest noncancer risk to exposure to acrolein. Such modeling studies, conducted by the U.S. Environmental Protection Agency (U.S. EPA), also predict median ambient air concentrations of acrolein higher than 0.06 microg/m3, the chronic inhalation reference exposure level stipulated by the California Office of Environmental Health Hazard Assessment in counties surrounding the Oakland-San Francisco Bay Bridge. We measured acrolein and other potentially toxic carbonyls in air sampled at the San Francisco Bay Bridge toll plaza during rush hour traffic, which may be considered a "worst case scenario" for outdoor airborne carbonyls. We identified 36 carbonyls in the sample extracts, including 14 saturated aliphatic carbonyls, six unsaturated carbonyls, four aromatic carbonyls, six dicarbonyls, and six hydroxy carbonyls. Structural information to support tentative identification of carbonyls and hydroxycarbonyls was obtained by using a method that involves O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and PFBHA/bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization in concert with gas chromatography/ion trap mass spectrometry. Most notably, we report for the first time the presence of malonaldehyde in the ambient atmospheric environment. A relatively linear relationship between retention time and the molecular weight of the derivatives was established to assist in obtaining structural information about chemicals for which authentic standards are not readily available. Levels of acrolein exceeded the California reference exposure level during morning rush hour traffic. The measured values, however, were significantly lower than estimates of county-wide average acrolein concentrations predicted by a U.S. EPA modeling study based on 1996 data. Successful regulatory efforts such as the introduction of reformulated gasoline, together with the advancement of new catalysts and fleet turnover throughout the 1990s, are likely to account for part of the gap between our determination and the 1996 levels.     

Oral omega-6 essential fatty acid treatment in contact lens associated dry eye

PURPOSE: Symptoms of dry eye are commonly reported in contact lens wearers and are a frequent cause of non-tolerance. The purpose of the present study is to evaluate the effects of oral treatment with particular omega-6 fatty acids in the form of evening primrose oil (EPO) on subjective symptoms, ocular surface signs and tear film characteristic in patients with contact lens associated dry eye. METHODS: The study design was randomised, double-masked and placebo controlled. 76 female soft contact lens wearers were treated for 6 months with either EPO or placebo (olive oil). Subjects underwent three examinations (baseline, 3 and 6 months). At each examination subjects were given a questionnaire relating to lens comfort and dry eye symptoms and underwent a series of tests of tear film characteristics (tear meniscus height, break-up time), meibomian gland function (lipid layer thickness and quality) and ocular surface parameters (hyperaemia and staining). RESULTS: The EPO group showed a significant improvement in the specific symptom of 'dryness' at 3 and 6 months (p<0.01) and also a significant improvement in overall lens comfort at 6 months (p<0.01). Tear meniscus height was increased in the EPO group at 6 months relative to baseline (p<0.01), although all other objective signs were unchanged. CONCLUSION: This study provides evidence for a beneficial effect of particular orally administered omega-6 fatty acids in alleviating dry eye symptoms and improving overall lens comfort in patients suffering from contact lens associated dry eye.     

Zinc Oxide Nanoparticles: Synthesis,Antimicrobial Activity and Food Packaging Applications

Zinc oxide (ZnO) is an inorganic compound widely used in everyday applications. ZnO is currently listed as a generally recognized as safe (GRAS) material by the Food and Drug Administration and is used as food additive. The advent of nanotechnology has led the development of materials with new properties for use as antimicrobial agents. Thus, ZnO in nanoscale has shown antimicrobial properties and potential applications in food preservation. ZnO nanoparticles have been incorporated in polymeric matrices in order to provide antimicrobial activity to the packaging material and improve packaging properties. This review presents the main synthesis methods of ZnO nanoparticles, principal characteristics and mechanisms of antimicrobial action as well as the effect of their incorporation in polymeric matrices. Safety issues such as exposure routes and migration studies are also discussed.     

Structure-texture relationships of fresh pastes prepared from different yam (Dioscorea spp.) varieties

Yam (Dioscorea spp.) presents an important tropical food crop rich in starch. In West Africa, yam is traditionally prepared by pounding of cooked yam to obtain a dough-like paste known as pounded yam or ‘foutou’. The present investigation deals with structure-texture relationships of yam pastes as influenced by yam varieties. In general, the firmness of yam pastes prepared from D. cayenensis-rotundata was higher than that from D. alata. Difference in firmness was found to be related to the extent of cell disintegration, which was more pronounced for D. alata as assessed by light microscopy. Pronounced textural changes were measured during ageing of yam pastes, which is a consequence of the reorganization (retrogradation) of the amylose fraction. Post-harvest storage of yam tubers resulted in increased firmness and decreased adhesion properties in the pastes, but no significant influence of the storage treatment with gibberellic acid, which reduces storage losses, was detected. It is concluded that the texture of yam pastes is largely determined by the integrity of cells and the properties of the continuous starch phase.     

The effects of acrolein on the thioredoxin system: implications for redox-sensitive signaling

The reactive aldehyde acrolein is a ubiquitous environmental pollutant and is also generated endogenously. It is a strong electrophile and reacts rapidly with nucleophiles including thiolates. This review focuses on the effects of acrolein on thioredoxin reductase (TrxR) and thioredoxin (Trx), which are major regulators of intracellular protein thiol redox balance. Acrolein causes irreversible effects on TrxR and Trx, which are consistent with the formation of covalent adducts to selenocysteine and cysteine residues that are key to their activity. TrxR and Trx are more sensitive than some other redox-sensitive proteins, and their prolonged inhibition could disrupt a number of redox-sensitive functions in cells. Among these effects are the oxidation of peroxiredoxins and the activation of apoptosis signal regulating kinase (ASK1). ASK1 promotes MAP kinase activation, and p38 activation contributes to apoptosis and a number of other acrolein-induced stress responses. Overall, the disruption of the TrxR/Trx system by acrolein could be significant early and prolonged events that affect many aspects of redox-sensitive signaling and oxidant stress.     

Increasing hypnotic susceptibility by means of positive expectancies and written instructions.

Investigated the extent to which hypnotic susceptibility could be modified by means of induced positive expectancies and written instructions that were designed to correct misconceptions concerning hypnosis as well as to provide concrete methods for experiencing hypnosis. 40 undergraduates were given a baseline test of hypnotic susceptibility and then randomly assigned to 1 of 4 conditions. Ss receiving the positive expectancy were given false personality test feedback that they were good hypnotic Ss prior to a criterion hypnotic scale. Ss receiving the written instructions were given 10 min to read the information prior to the hypnotic test. Other Ss browsed through magazines prior to testing in hypnosis. Both positive expectancies and written instructions were significantly effective in increasing susceptibility in comparison with practice only. Theoretical explanations are advanced and the implications of these findings are considered. (26 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prevalence and characteristics of overweight and obesity in indigenous Australian children: A systematic review

Evidence-based profiling of obesity and overweight in Indigenous Australian children has been poor. This study systematically reviewed evidence of the prevalence and patterns of obesity/overweight, with respect to gender, age, remoteness, and birth weight, in Indigenous Australian children, 0–18 years (PROSPERO CRD42014007626). Study quality and risk of bias were assessed. Twenty-five publications (21 studies) met inclusion criteria, with large variations in prevalence for obesity or overweight (11 to 54%) reported. A high degree of heterogeneity in study design was observed, few studies (6/21) were representative of the target population, and few appropriately recruited Indigenous children (8/21). Variability in study design, conduct, and small sample sizes mean that it is not possible to derive a single estimate for prevalence although two high-quality studies indicate at least one in four Indigenous Australian children are overweight or obese. Four of six studies reporting on gender, found overweight/obesity higher in girls and eight studies reporting on overweight/obesity by age suggest prevalence increases with age with one high quality large national study reporting total overweight/obesity as 22.4% of children aged 2–4 years, 27.5% of those aged 5–9, 38.5% aged 10–14, and 36.3% aged 15–17. Three of four studies, reporting obesity/overweight by region, found lower rates for children living in more remote areas than urban areas.     

Inhibitions of cotton seedling growth by volatile ketones emitted by cover crop residues

Low-input, sustainable agriculture (LISA) systems can include soil incorporation of residues of weeds and legume cover crop species. However, both seed germination and seedling growth of crops, including cotton (Gossypium hirsutum L.), are inhibited by volatile organic compounds emitted by these residues during decomposition. A cotton seedling-growth assay was used to demonstrate that C₄ through C₉ ketones released by decomposing legume residues significantly inhibited root and shoot elongation, root and shoot fresh and dry weight gain, and cotyledon expansion. Seedling root and shoot water relationships were relatively insensitive to those components of plant residue volatile emissions. Concentration (0.0, 0.5, 1.0, 1.5, or 2.0M/cm³ sterile greenhouse soil mix) and root-zone temperature (20 or 30°C) altered the activity of the more inhibitory ketones. Molecular weight (carbon chain length), carbon chain branching, and position of the carbonyl group also influenced ketone inhibitory activity.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture.     

Fatty acid desaturase systems of hen liver and their inhibition by cyclopropene fatty acids

Hen liver preparations which desaturate stearic acid at the 9,10 position to form oleic acid have been found to desaturate other saturated fatty acids of carbon chain length from 12 to 20 and 22. The 9,10-monoenoic fatty acid of the same chain length as the substrate fatty acid is the major product formed. Minor amounts of the 10,11- and 11, 12-monoenoic acids are also formed. Maximum desaturation occurred with the C₁₄ fatty acid substrate and with the fatty acids C₁₇ and C₁₈, suggesting the presence of at least two desaturating systems. The cyclopropene fatty acids, sterculic and malvalic acids, inhibited the desaturation of all thefatty acids at the 9,10 position but desaturation at the 10,11 and 11, 12 positions was affected only slightly. The effect is not due to inhibition of the primary activating enzyme, the long chain acyl CoA synthetase. Sterculic acid is a more effective inhibitor than either malvalic acid or sterculyl alcohol, probably because these cyclopropene compounds do not block the desaturating site of the enzyme as completely as sterculic acid.     

Thick lead-free ferroelectric films with high Curie temperatures through nanocomposite-induced strain

Ferroelectric materials are used in applications ranging from energy harvesting to high-power electronic transducers. However, industry-standard ferroelectric materials contain lead, which is toxic and environmentally unfriendly. The preferred alternative, BaTiO(3), is non-toxic and has excellent ferroelectric properties, but its Curie temperature of ～130 °C is too low to be practical. Strain has been used to enhance the Curie temperature of BaTiO(3) (ref. 4) and SrTiO(3) (ref. 5) films, but only for thicknesses of tens of nanometres, which is not thick enough for many device applications. Here, we increase the Curie temperature of micrometre-thick films of BaTiO(3) to at least 330 °C, and the tetragonal-to-cubic structural transition temperature to beyond 800 °C, by interspersing stiff, self-assembled vertical columns of Sm(2)O(3) throughout the film thickness. The columns, which are 10 nm in diameter, strain the BaTiO(3) matrix by 2.35%, forcing it to maintain its tetragonal structure and resulting in the highest BaTiO(3) transition temperatures so far.