Search results for "cyclic"
showing 10 items of 2439 documents
Comparison of the Phytotoxkit microbiotest and chemical variables for toxicity evaluation of sediments
2006
The main objective of the research was to evaluate the suitability of the Phytotoxkit microbiotest as a tool for hazard assessment of sediments. The concentrations of oil derivatives, polycyclic aromatic hydrocarbons (PAHs), and heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) were determined in sediment samples collected from the urban canal in Opole (Poland), in order to obtain a general insight of the level of sediment contamination. Phytotoxicity of sediments was estimated on the basis of seed germination and root elongation measurements, combined into an overall germination index (Gl). The results revealed spatial and vertical differentiation in sediment contamination. A good correlation …
Bioaccumulation of PAHs from creosote-contaminated sediment in a laboratory-exposed freshwater oligochaete, Lumbriculus variegatus
2002
The oligochaete, Lumbriculus variegatus, was used for a bioaccumulation assay in the creosote-contaminated sediment of Lake Jämsänvesi in a 28-day experiment. The PAH concentrations of the whole body tissue of worms, sediments and water samples were determinated by GC-MS. Chemical analyses showed that benzo(k)fluoranthene, anthracene and fluorene were the main PAH compounds present in the tissue of oligochaetes, just as in the sediment. The biota-sediment accumulation factors (BSAFs) of the individual PAHs varied from 1.2 to 5.7. It is concluded that oligochaetes have a marked ability to accumulate and retain PAHs from creosote-contaminated sediment.
Sorption of polycyclic aromatic hydrocarbons (PAHs) to carbonaceous materials in a river floodplain soil
2007
We report on sorption isotherm of phenanthrene (Phe) for river floodplain soil associated with carbonaceous materials, with particular attention being devoted to the natural loading of Phe. Our sorption experiments with original soil samples, size, and density sub-fractions showed that the light fraction had the highest sorption capacity comparable to low rank coals. In addition, the light fraction contributed most for the sorption of Phe in total soil samples. K(oc) values for all fractions were in the same range, thus indicating that coal and coal-derived particles in all samples are responsible for the enhanced sorption for Phe. Sorption was strongly nonlinear and the combined partitioni…
Cleaning sorbents used in matrix solid-phase dispersion with sonication: Application to the estimation of polycyclic aromatic hydrocarbons at ng/g le…
2012
This study shows that ultrasonic assisted extraction is a good practise for removing impurities from sorbents used for matrix-solid phase dispersion (MSPD). A previous washing of the sorbent with an organic solvent or mixture of solvents eliminates part of the interferences, but this treatment is not enough for the quantification of PAHs at ng/g levels. It is demonstrated that the determination of traces of polycyclic aromatic hydrocarbons (PAHs) in solid samples processed by matrix-solid phase dispersion (MSPD) may be severely affected by the presence of sorbent impurities. Different extraction solvents and sonication conditions have been tested, and on the basis of the results obtained a …
BIOAVAILABILITY TO JUVENILE RAINBOW TROUT (ONCORYNCHUS MYKISS) OF RETENE AND OTHER MIXED-FUNCTION OXYGENASE-ACTIVE COMPOUNDS FROM SEDIMENTS
2002
Retene (7-isopropyl-1-methylphenanthrene) is a naturally formed polycyclic aromatic hydrocarbon (PAH) that causes teratogenicity in fish larvae and induction of cytochrome P450 (CYP1A) enzymes. Retene occurs at high concentrations (or =3,300 microg/g dry wt) in surface sediments contaminated by resin acids from pulp mill effluents. To assess the environmental risks of retene, it is important to evaluate conditions affecting its bioavailability and accumulation by fish. Fingerling rainbow trout were exposed to retene-spiked or naturally contaminated sediments and sampled after 4 d to determine liver CYP1A activity and concentrations of retene metabolites in bile as indicators of retene accum…
Germacranolides and a monoterpene cyclic peroxide from Artemisia fragrans
1998
Abstract The aerial parts of Artemisia fragrans collected in Armenia yielded a new cyclic monoterpene peroxide with the irregular santolinyl framework, together with several known germacranolides. Comparison with previously published chemical results suggests these may actually have been performed on a different, although closely related species.
Application of liquid-liquid partition chromatography in the simultaneous purification of sex-hormone-binding globulin and corticosteroid-binding glo…
1987
Two human serum proteins, corticosteroid-binding globulin (CBG) and sex-hormone-binding globulin (SHBG), were purified to homogeneity by the application of a combination of three different modes of chromatography. Human pregnancy serum was fractionated with ammonium sulphate. SHBG (50% pellet) and CBG (80% pellet) were then purified by affinity chromatography on tresyl-activated Sepharose with 15-aminopentadecanoic acid (for SHBG) and 1,12-diaminododecane (for CBG) as spacers and 17 zeta-aminoethyl-5 alpha-androstan-3 beta,17-diol (for SHBG) and 17 alpha-hydroxy-4-androsten-3-one-17 beta-carboxylic acid (for CBG) as specific ligands for these two proteins. The eluate was injected into a Mon…
(R)-NODAGA-PSMA: A Versatile Precursor for Radiometal Labeling and Nuclear Imaging of PSMA-Positive Tumors
2015
Purpose The present study aims at developing and evaluating an urea-based prostate specific membrane antigen (PSMA) inhibitor suitable for labeling with 111In for SPECT and intraoperative applications as well as 68Ga and 64Cu for PET imaging. Methods The PSMA-based inhibitor-lysine-urea-glutamate-coupled to the spacer Phe-Phe-D-Lys(suberoyl) and functionalized with the enantiomerically pure prochelator (R)-1-(1-carboxy-3-carbotertbutoxypropyl)-4,7-carbotartbutoxymethyl)-1,4,7-triazacyclononane ((R)-NODAGA(tBu)3), to obtain (R)-NODAGA-Phe-Phe-D-Lys(suberoyl)-Lys-urea-Glu (CC34). CC34 was labeled with 111In, 68Ga and 64Cu. The radioconjugates were further evaluated in vitro and in vivo in LNC…
Validation of brain extracellular glycerol as an indicator of cellular membrane damage due to free radical activity after traumatic brain injury.
2008
Following severe traumatic brain injury (TBI), increasing oxygen delivery to the brain has been advocated as a useful strategy to reverse mitochondrial dysfunction and improve neurological outcome. However, this might also promote overproduction of free radicals, responsible for lipid peroxidation and hence brain cell damage. Therefore, a method for monitoring this potential adverse effect in humans is desirable. Glycerol, an end product of phospholipid breakdown, easily detectable in the human brain by means of microdialysis, might represent a reliable indicator of free radical-induced cell membrane damage. Brain microdialysates were collected from 24 adult male Sprague-Dawley rats over a …
Physiology and genetics of antibiotic production and resistance.
1993
Actinomycetes have the genetic capability to synthesize many different biologically active secondary metabolites and of these compounds, antibiotics predominate in therapeutic and commercial importance. Intensive research often centres on the use of molecular techniques to investigate the physiology and genetics of antibiotic biosynthesis with a view to improving production. The isolation of clones of Streptomyces hygroscopicus, the producer of geldanamycin, which synthesizes geldanamycin in S. lividans, is reported. Molecular approaches using genes for elongation factors (tuf) were used in attempts to increase the fermentation yield of kirromycin, whilst probes for aphD and sph, genes for …