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51.
Teresa Coccini Luigi Manzo Frodi Debes Ulrike Steuerwald Pál Weihe Philippe Grandjean 《Biomarkers》2013,18(2):67-76
Experimental evidence suggests that monoamine oxidase B (MAO-B) and muscarinic cholinergic receptors (mAChRs) are involved in the pathogenesis of neurotoxicity caused by methylmercury and polychlorinated biphenyls (PCBs). Blood samples from 7-year-old exposed children were analyzed for platelet MAO-B and lymphocyte mAChRs as potential markers of exposure to these neurotoxicants. The blood neurotoxicity biomarkers were compared with prenatal and current exposures and with neuropsychological test results. Both biomarkers showed homogeneous distributions within this cohort (mAChR, range 0.04–36.78?fmol/million cells; MAO-B, 0.95–14.95?nmol mg?1 protein h?1). No correlation was found between the two biomarkers and either blood neurotoxicant concentrations or clinical findings. MAO-B and mAChR sensitivity may not be sufficiently high to assess early, subclinical responses to low/moderate methylmercury and/or PCB exposure, whereas these markers are significantly altered in sustained exposure scenarios, as shown by clinical studies in drug addicts or patients treated with psychopharmacological agents. 相似文献
52.
In this paper, a simple and novel method for the determination of polychlorinated biphenyls (PCBs), using silver nanoparticles (AgNPs) as a resonance light scattering (RLS) probe, is proposed. Under optimized conditions, there existed linear relationships between the enhancing RLS intensity of the system and the concentrations of PCBs in the range 8.0 × 10?8?1.0 × 10?6 g mL?1 for 2,4,4′‐trichlorbiphenyl (PCB28), 9.0 × 10?8?1.0 × 10?6 g mL?1 for 2,2′,5,5′‐tetrachlorbiphenyl (PCB52) and 4.0 × 10?8?1.0 × 10?6 g mL?1 for 3,3′,4,4′‐tetrachlorobiphenyl (PCB77). The corresponding detection limits (S/N = 3) were 2.6 × 10?8 g mL?1 for PCB28, 3.3 × 10?8 g mL?1 for PCB52 and 6.3 × 10?9 g mL?1 for PCB77, respectively. Finally, the mechanism of RLS enhancement was also studied. The results indicated that PCBs were adsorbed on the surface of AgNPs to form larger AgNP–PCB aggregates, resulting in the RLS enhancement of the system. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
53.
A soy sauce sample was fractionated by gel filtration on a Sephadex G–15 column, then the fractions were subfractionated on the basis of acidity by ion exchange chromatography on a QAE-Sephadex A–25 column. The acidic subfractions with various acidities were further fractionated, using a preparative amino acid analyzer and by paper chromatography to separate the acidic peptide components.Four dipeptides and sugar derivatives of ten dipeptides and two tripeptides were isolated and characterized as the major acidic peptides in soy sauce. However, it was difficult to anticipate any direct contribution of these peptides to the flavor construction in soy sauce on the basis of their contents and taste intensities. 相似文献
54.
Soybean seedlings were grown at 28°C in the dark or the light for 12 days, and four classes of sterol lipids, sterol esters (SE), free sterols (St), acylated steryl glycosides (ASG) and steryl glycosides (SG), were isolated from the cotyledons by solvent extractions, Florisil column chromatography, and thin-layer chromatography (TLC), successively. Each sterol lipid (SE, ASG and SG) obtained was hydrolyzed and then separately divided into sterol, fatty acid and/ or sugar fractions. The hydrolysates and St were analyzed mainly by gas-liquid chromatography (GLC).Under the two conditions tested, the main sterol lipid class was St during germination, the minor one being SG. With the progress of germination, St and ASG decreased under both conditions tested, whereas SE and SG increased, especially SE in the light-grown seedlings. The changing patterns of sterol and sugar compositions of ASG resembled those of SG, but those of fatty acid composition differed between SE and ASG. In general, the changes in fatty acid compositions of SE and ASG were more marked in the light-grown seedlings than in the dark-grown ones. 相似文献
55.
56.
Kawashima A Akihiro H Morita H Fukuoka M Honda K Morita M 《Bioresource technology》2011,102(7):4682-4687
In this study, the effective utilization of lignocellulose residue as an adsorbent was investigated. Japanese cypress wood flour subjected to hydrothermal pretreatment and ball-mill grinding was saccharified with an enzyme. The residual wood flour was carbonized and activated by physical and chemical activation to produce adsorbents for persistent organic pollutant removal. The adsorption properties were investigated by pore analysis using the N2 adsorption/desorption isotherm and adsorption tests for dioxin-like polychlorinated biphenyls in a hexane solution. The obtained adsorbents showed high production yields and adsorption properties for dioxin-like polychlorinated biphenyls. 相似文献
57.
A suite of experiments were conducted to ascertain whether dehalogenation of a model dioxin compound could be stimulated in marine sediments by supplementation with halogenated analogues to enrich for dehalogenating bacteria and if growth by members of the Chloroflexi-like group was associated with dioxin removal. Five halogenated compounds (tetrachlorobenzene, tetrachloroanisole, tetrachlorophenol, tetrachlorobenzoic acid and trichloroacetophenone) were added with 1,2,3,4-tetrachlorodibenzo-p-dioxin (TeCDD) to estuarine sediments from four sites in San Diego Bay and the coast of southern New Jersey to test for dioxin dehalogenation. Most of the halogenated additives were found to stimulate dechlorination of the model dioxin. Molecular analysis of the bacterial population using 16S rRNA and reductive dehalogenase genes indicated that distinct microbial populations were enriched with each halogenated co-amendment. Additionally, Chloroflexi-like ribosomal genes associated with dehalogenation were detected. For example, quantitative real-time PCR analysis of 16S rRNA and reductive dehalogenase gene copy number in the microcosms showed a positive correlation with 1,2,3,4-TeCDD reductive dechlorination in coastal sediments amended with different halogenated additives. These results suggest that specific Chloroflexi-like microorganisms related to Dehalococcoides are involved in 1,2,3,4-TeCDD reductive dechlorination. 相似文献
58.
AIMS: The present work investigates the possibility that temperature could regulate the pattern of transformation of 2,4'-chlorobiphenyl (2,4'-CB) by psychrotolerant Hydrogenophaga sp. IA3-A. Methods AND RESULTS: Transformation of 2,4'-chlorobiphenyl to 2- and 4-chlorobenzoic acid (2- and 4-CBA), and meta-cleavage products by cells of strain IA3-A incubated at 10 degrees C, 25 degrees C, 37 degrees C or 45 degrees C were monitored by UV spectrometry, HPLC and GC-MS analyses. Cultures incubated at 10 degrees C, 25 degrees C or 37 degrees C produced low amounts of CBAs and excess levels of meta-cleavage products from 2,4'-CB. Cultures incubated at 45 degrees C transformed most of the degraded 2,4'-CB to CBAs and low level of meta-cleavage product. Culture extracts contained unusual varieties of isomeric hydroxylated metabolic products. CONCLUSIONS: Efficient transformation of 2,4'-CB to CBAs was possible in cultures incubated at 45 degrees C. Evidence for the involvement of multiple pathways in the transformation of 2,4'-CB in strain IA3-A suggests that differential regulation of the pathways at different temperatures was likely responsible for the change in the pattern of transformation of 2,4'-CB in cultures incubated at 45 degrees C. Significance AND IMPACT OF THE STUDY: It may be possible to condition cells to transform chlorinated biphenyls more efficiently without accumulating excess level of toxic intermediates. 相似文献
59.
A Monte Carlo model was developed to characterize the molecular composition of polychlorinated alkane mixtures. The model
is based upon a simulation of the free-radical chlorination process by which polychlorinated alkane mixtures are produced
industrially from n-alkanes. In the model, the free-radical chlorination reaction was simulated by randomly selecting a position on a partially
converted alkane molecule for target by chlorine free-radical attack. The relative reactivities of the hydrogen atoms on the
alkane chain towards chlorine free-radical substitution were either determined experimentally or extrapolated from experimental
results and incorporated into the model. The result of the simulation is the prediction of the detailed molecular composition
of any PCA mixture. Good agreement was found when comparing the distribution of molecules predicted by the model to analytically
determined distributions of real PCA mixtures. Results from the model were then coupled with rules describing the action of
biological enzymes to estimate the upper limit possible for the aerobic biodegradation of PCA mixtures. 相似文献
60.
Rhodococcus sp. RHA1 is a Gram-positive actinomycete capable of metabolizing a wide spectrum of organic compounds whose survival in chemically hostile environments is believed to be in part due to the production of an exocellular polysaccharide (EPS). In order to investigate the functional nature of the EPS, its structure was determined using a combinatory approach including hydrolysis, composition, and methylation, analysis methods, as well as 2D (1)H and (13)C NMR spectroscopy. The EPS was found to be a high-molecular-mass polymer of a repeating tetrasaccharide unit composed of D-glucuronic acid, D-glucose, D-galactose, L-fucose and O-acetyl (1:1:1:1:1), and has the structure: 相似文献