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PubMedDate not supplied

The modulating activity of interferon on benzo(a)pyrene bioactivation and clastogenesis in mice.

Acute intraperitoneal administration of benzo(a)pyrene (80 mg/kg b.wt.) resulted in time-dependent increases in chromosome aberrations, especially of break-type in the bone marrow of treated mice. Pretreatment with murine interferon-alpha/beta (5 x 10(4) IU daily for two days) caused a significative decrease in the cytogenetic response in vivo of benzo(a)pyrene (up to 51%) and a stabilization of aberrant cells up to 48 hr. The administration of murine interferon-alpha/beta gave rise to a marked depression of microsomal monooxygenase system after 24 hr, as exemplified by the significant reduction of cytochrome P450 content as well as deethylation of ethoxyresorufin. Interferon treatment delayed the obtainment of basal levels of oxidative metabolism to approximately 30 hr. After interferon plus benzo(a)pyrene treatment, ethoxyresorufin O-deethylase activity showed a reduction up to 60%; levels comparable to benzo(a)pyrene treated group were restored by 48 hr. Immunoblotting analysis confirmed reduced CYP1A1 level. Results suggest that the inhibition of benzo(a)pyrene hepatic metabolism by interferon was reflected by changes in its clastogenic activity. Persistence of low level of chromosome aberration at 48 hr may be reconducible to other interferon sensitive processes than effects on hepatic mixed-function oxidase system, such as DNA repair activity and cell proliferation.

Animals↗
PubMed1996

Uptake of 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene in melanin-containing tissues.

It is widely accepted that UV exposure is the main etiological factor for malignant melanoma. Epidemiologic studies, however, have indicated that also chemical carcinogens may be a risk factor for the disease. Polycyclic aromatic hydrocarbons such as 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene represent an important class of carcinogenic chemicals. It is known that 7,12-dimethylbenz(a)anthracene can induce melanotic tumours in various animal species, and human melanocytes in culture have been found to be capable of metabolizing benzo(a)pyrene to its proximate carcinogen benzo(a)pyrene-7,8-diol. In the present study the disposition of 14C- and 3H-7,12-dimethylbenz(a)anthracene and 14C-benzo(a)pyrene was studied in pigmented and albino mice and Syrian golden hamsters by whole-body autoradiography. The results showed pronounced retention of label in the melanin-containing structures of the eyes and the hair follicles in the pigmented animals. The labelling of the corresponding structures in the albino animals was low. Additional experiments showed that 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene as well as some of their metabolites are bound to melanin in vitro. The specific localization of the polycyclic aromatic hydrocarbons in pigmented tissues due to melanin affinity, combined with bioactivating capacity of melanocytes, suggest that these substances may play a role in the induction of malignant melanoma.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2006

Preventive effects of quercetin against benzo[a]pyrene-induced DNA damages and pulmonary precancerous pathologic changes in mice.

The aim of this study was to investigate the preventive effects of quercetin against benzo[a]pyrene-induced blood lymphocyte DNA damages and pulmonary precancerous pathologic changes in mice, and to reveal the potential mechanism behind these effects. In this study, mice in quercetin-treated groups were given quercetin for 90 days. After one week of treatment, mice in the quercetin-treated groups and the positive control group received a single intraperitoneal dose of benzo[a]pyrene (100 mg/kg body weight). The results of single cell gel electrophoresis assay showed that the average lengths of the comet cell tail and DNA damage in the peripheral blood lymphocytes of mice induced by benzo[a]pyrene decreased significantly as a result of quercetin treatment dose-dependently. Light microscopic examination showed that the degrees of pulmonary precancerous pathologic changes in the quercetin-treated groups decreased significantly compared with those in the positive control group. Meanwhile, the cytochrome P4501A1-linked 7-ethoxyresorufin O-dealkylase activities in lung microsomes of mice decreased as the dose of quercetin increased. The results of this in vivo study revealed that quercetin had a significant preventive effect on benzo[a]pyrene-induced DNA damage, and had a potential chemopreventive effect on the carcinogenesis of lung cancer induced by benzo[a]pyrene. The mechanism of these effects of quercetin could be related to the inhibition of cytochrome P4501A1 activity.

Animals↗
PubMed1988

Pyrene degradation by a Mycobacterium sp.: identification of ring oxidation and ring fission products.

The degradation of pyrene, a polycyclic aromatic hydrocarbon containing four aromatic rings, by pure cultures of a Mycobacterium sp. was studied. Over 60% of [14C]pyrene was mineralized to CO2 after 96 h of incubation at 24 degrees C. High-pressure liquid chromatography analyses showed the presence of one major and at least six other metabolites that accounted for 95% of the total organic-extractable 14C-labeled residues. Analyses by UV, infrared, mass, and nuclear magnetic resonance spectrometry and gas chromatography identified both pyrene cis- and trans-4,5-dihydrodiols and pyrenol as initial microbial ring-oxidation products of pyrene. The major metabolite, 4-phenanthroic acid, and 4-hydroxyperinaphthenone and cinnamic and phthalic acids were identified as ring fission products. 18O2 studies showed that the formation of cis- and trans-4,5-dihydrodiols were catalyzed by dioxygenase and monooxygenase enzymes, respectively. This is the first report of the chemical pathway for the microbial catabolism of pyrene.

Biodegradation, Environmental↗
PubMed1991

Photosensitized killing of cultured fibroblasts from patients with peroxisomal disorders due to pyrene fatty acid-mediated ultraviolet damage.

The influence of pyrene-fatty acids on the resistance of cells to ultraviolet (UV) radiation was investigated in cultured fibroblasts from patients with five types of peroxisomal disorders. All showed reduced survival compared to control. The effect varied with the biochemical defect involved and the chain length of the pyrene fatty acid. Reduced survival was observed in cells deficient in plasmalogens (rhizomelic chondrodysplasia punctata) and in cells deficient in peroxisomal fatty acid oxidation (bifunctional enzyme deficiency), which accumulated pyrene-fatty acids. X-linked adrenoleukodystrophy fibroblasts accumulated pyrene-fatty acids and showed increased UV sensitivity only when exposed to longer-chain pyrene fatty acids. UV radiation resistance was lowest in cells with combined impairment of plasmalogen synthesis and fatty acid oxidation (Zellweger syndrome, neonatal adrenoleukodystrophy), suggesting that UV sensitivity correlates inversely with the ratio of plasmalogens to radical producing substances. Fibroblasts deficient in plasmalogens gained normal UV resistance when their plasmalogen levels were normalized by hexadecylglycerol. UV resistance increased when Zellweger cells were fused with X-linked adrenoleukodystrophy cells, and also when Zellweger cells belonging to different complementation groups were fused. The results provide leads to the pathogenesis of the multiple malformations associated with peroxisomal disorders and a method for the selection of cells in which the metabolic defect has been corrected.

Adrenoleukodystrophy↗
PubMed1983

Effect of chrysotile asbestos and silica on the microsomal metabolism of benzo(a)pyrene.

The effects of chrysotile, water-leached chrysotile, and silica on microsomal metabolism of benzo(a)pyrene in vitro were studied. Examination of benzo(a)pyrene metabolites generated by 3-methylcholanthrene-pretreated rat liver microsomes, in the presence of chrysotile fibers, revealed a reduction in the overall metabolism of the hydrocarbon. Thus, chrysotile appeared to modify the activities of aryl hydrocarbon hydroxylase and epoxide hydrolase. Leaching chrysotile in deionized water for 24 hr elicited a similar response. Silica, in contrast to chrysotile, did not decrease the microsomal metabolism of benzo(a)pyrene. Chrysotile, as well as water-leached chrysotile, considerably diminished the microsomal production of water-soluble benzo(a)pyrene metabolites. Precoating the fibers with heparin or bovine serum albumin partially abolished this inhibition. The liver microsomal metabolism of benzo(a)pyrene in rats subjected to intraperitoneal administration of chrysotile was 58% of that in untreated rats.

Animals↗
PubMed1983

Presentation of benzo(a)pyrene to microsomal enzymes by asbestos fibers in the Salmonella/mammalian microsome mutagenicity test.

The potential effect of asbestos fibers on mutagenicity of benzo(a)pyrene was investigated by using the Ames test. Asbestos fibers without a coating of benzo(a)pyrene or benzo(a)pyrene when not dissolved in DMSO lacked any mutagenic effect in the Salmonella/mammalian microsome mutagenicity test. However, when benzo(a)pyrene was adsorbed onto asbestos, significant numbers of mutated bacteria were observed. This shows that asbestos fibers can serve a carrier role presenting benzo(a)pyrene to the enzymatic microsomal system, thus enhancing mutagenicity of this compound.

Adsorption↗
PubMed2004

2H-NMR study and molecular dynamics simulation of the location, alignment, and mobility of pyrene in POPC bilayers.

The alignment of pyrene in a 1-palmitoyl-2-oleoyl-phosphatidylcholine bilayer was investigated using two different approaches, namely solid-state (2)H-NMR spectroscopy and molecular dynamics (MD) simulations. Quadrupolar splittings from (2)H-NMR spectra of deuterated pyrene-d(10) in an oriented lipid bilayer give information about the orientation of C-D bonds with respect to the membrane normal. From MD simulations, geometric information is accessible via trajectories. By defining molecular and bond order parameters, the data from MD trajectories and NMR spectra can be compared straightforwardly. To ensure that the results from both methods are comparable, parameters of the experimental and the simulation setup were chosen to be as similar as possible. From simulations, we saw that pyrene prefers a position inside the lipid membrane near the headgroups and has no tendency to diffuse from one monolayer of the membrane to the other. The results from simulation and NMR show that the normal of the molecular plane is aligned nearly perpendicular to the bilayer normal. The long axis of pyrene lies preferentially parallel to the bilayer normal within a range of +/-30 degrees . The results from the two different methods are remarkably consistent. The good agreement can be explained by the fact that the different kind of motions of a pyrene molecule are already averaged within a few nanoseconds, which is the timescale covered by the MD simulation.

Computer Simulation↗
PubMed2006

Role of sediment organic matter quality and feeding history in dietary absorption and accumulation of pyrene in the mud snail (Hydrobia ulvae).

Organic matter (OM) input to marine sediments varies seasonally both in quantity and quality. Because sedimentary OM (SOM) constitutes food for many benthic organisms, its properties should affect the dietary uptake of sediment-associated contaminants. We explored the effect of SOM quality/food value on short- and long-term pyrene accumulation in the mud snail (Hydrobia ulvae) and performed dual-tracer pulse-chase experiments to investigate the feeding mechanisms driving dietary pyrene uptake. The quality of the SOM was manipulated by enriching sediments either with high-quality microalgae or low-quality lignin, adding equal amounts of total organic carbon. Long- and short-term bioaccumulation increased with increasing SOM quality, as did pyrene ingestion rate (IR(pyr)), which also was affected by feeding history. By feeding selectively, snails concentrated pyrene 10-fold in ingested compared to ambient sediment, independent of SOM quality. Average pyrene absorption efficiency (AE(pyr): -65%) varied inversely with SOM quality and IR(pyr). Both AE(pyr) and gut passage time (alpha 1/IR(pyr)) agreed with theoretical models incorporating the time-dependence of absorption efficiency. Thus, SOM quality moderates dietary contaminant uptake in deposit feeders, and in H. ulvae, this occurs via OM-induced alterations of ingestion rate. Consequently, enhanced sediment-associated contaminant uptake is predicted for deposit feeders following phytoplankton blooms, principally because of OM quality-driven increases in the ingestion rate.

Animal Feed↗
PubMedDate not supplied

Effects of mineral surfaces on pyrene partitioning to well-characterized humic substances.

Mineral surfaces can alter the ability of humic substances (HS) to bind hydrophobic organic contaminants. In this study, complete adsorption (i.e., to avoid HS adsorptive fractionation effects) of a small subset of well-characterized terrestrial and aquatic HS on kaolinite and hematite significantly changed their subsequent organic carbon-normalized partition coefficients K(ads)(oc) for pyrene relative to their original respective dissolved organic carbon-normalized partition coefficients K(dis)(oc). Parallel experiments with ultrafiltration (UF) fractions obtained from purified Aldrich humic acid (PAHA) (Aldrich Chemical, Milwaukee, WI) gave similar results. The heterogeneity among the PAHA UF fractions was examined via their mineral surface adsorption characteristics and their subsequent ability to bind pyrene. As expected, variations in maximum adsorption densities (q(max)), Langmuir adsorption constants (K(q)), and pyrene K(ads)(oc) values were observed among the PAHA UF fractions. However, general trends of q(max), K(q), and pyrene log K(ads)(oc) values for the PAHA UF fractions versus the logarithm of their weight-average molecular weights (MW(w)) did not typically match the corresponding trends obtained with the four aquatic and terrestrial HS. In general, an ideal mixture competitive adsorption model gave reasonable predictions for PAHA sorption to kaolinite and hematite based on their corresponding UF isotherm parameters. Ideal mixture predictions of pyrene partitioning to adsorbed PAHA from the corresponding UF fraction results were better for kaolinite versus hematite, indicating that the underlying mineral surface can alter the effects of HS heterogeneity on hydrophobic organic contaminant sorption.

Adsorption↗
PubMed1982

The metabolism of pyrene by rat liver microsomes and the influence of various mono-oxygenase inducers.

1. Pyrene metabolite g.l.c. profiles were recorded and metabolites identified by mass spectrometry. 2. Pyrene is metabolized by liver microsomes of untreated rats to 1-hydroxypyrene, 4,5-dihydroxy-4,5-dihydropyrene, two different diphenols and a triol, tentatively identified as 1,4,5-trihydroxy-4,5-dihydropyrene. 3. Pretreatment with phenobarbital or polychlorinated biphenyls favours oxidation at the K-region, whereas cytochrome P-448 inducers stimulate oxidation at the non-K-region of pyrene. 4. 1-Hydroxypyrene does not inhibit pyrene oxidation. 5. Pyrene diphenols are formed by secondary oxidation of 1-hydroxypyrene. 6. Triols are formed from dihydrodiols by secondary oxidation.

Animals↗
PubMed1982

Metabolism and excretion of benzo[a]pyrene in the rabbit.

1. Following i.v. administration of [14C]benzo[a]pyrene (3 mumol/kg) to rabbits, 30% of the 14C dose appeared in bile and 12% in urine, within six hours. 2. Biliary and urinary metabolites were mainly conjugated; less than 12% of the 14C was extractable with ethyl acetate, but after treatment with beta-glucuronidase or aryl sulphatase 30-40% became extractable. 3. H.p.l.c. analysis of the extracts indicated that the major non-polar metabolite was benzo[a]pyrene, 9,10-diol (18% of 14C in bile and 24% of 14C in urine, mainly conjugated with glucuronic acid). Smaller amounts of the 4,5-diol, the 3,6-quinone, and the 9-hydroxy- and 3-hydroxybenzo[a]pyrene were also found in bile (total less than 10%), together with 9-hydroxybenzo[a]pyrene and two unknown metabolites (X and Y) in urine (total less than 4%). 4. The proximate carcinogen, the 7,8-diol, was not detected in any extract. 5. After intraduodenal administration of biliary metabolites of [14C]benzo[a]pyrene (approx. 0 X 3 mumol), 14C was excreted in the bile (21% dose) and urine (14%) within 23 h, indicating that metabolites can undergo enterohepatic circulation in the rabbit.

Animals↗
PubMed1994

Urinary and biliary metabolites of pyrene in rainbow trout (Oncorhynchus mykiss).

1. Pyrene was administered i.p. as a single dose to trout (Oncorhynchus mykiss). Urine was collected continuously for 3 days and bile sampled at the end of this period. Pyrene metabolites in these biological fluids were identified by 1H-nmr spectrometry, glc-ms and hplc-ms. 2. 1-Hydroxypyrene was the major oxidation metabolite in the urine and bile. Small amounts of 1,6-dihydroxypyrene and a putative 1,8-dihydroxypyrene metabolite also were detected. Unchanged pyrene was not found in any of these biological fluids. 3. Both free and conjugated metabolites of pyrene were found in the bile and urine. The majority of the pyrene metabolites in the bile were conjugated with glucuronic acid or sulphate.

Animals↗
PubMed2003

Relationship between concentration of pyrene and aerosol size distribution in traffic exhausts in Taipei, Taiwan.

Variations in pyrene concentrations in motor-vehicle emissions were assessed on the basis of aerodynamic particle size and by the type of vehicle (i.e., car, truck, or bus) that passed through a Taipei, Taiwan, highway toll station. Airborne particles were collected with 8-stage cascade samplers equipped with 34-mm polyvinyl chloride filters and located in the breathing zones of toll-station workers. The authors used gas chromatography/mass spectrometry to analyze 22 polycyclic aromatic hydrocarbons that were collected. The absolute concentration of pyrene was highest in the fine-particle emission fraction for trucks, buses, and passenger cars; however, fine particles in truck and bus exhausts contained higher pyrene concentrations than the corresponding size fraction of particles emitted from passenger cars. Truck and bus emissions contained a higher concentration of pyrene than car emissions because trucks and buses produced greater amounts of fine and coarse particles, and their fine particles contained higher concentrations of pyrene.

Meteorological Concepts↗
PubMedDate not supplied

[Use of excimerization of pyrene for assessing lipid microviscosity in biological membranes].

A method for estimating the fluidity of natural membranes from the pyrene excimer/monomer fluorescence ratio (Ie/Im) is proposed. The method makes it possible to exclude artefacts such as fluorescence quenching, aggregation, and redistribution of the probe in lipid mains with different microviscosity. It is shown that, upon variation of intramembrane pyrene concentration [pyr], the occurrence of a common crossover point in pyrene fluorescence spectra normalized to the corresponding probe concentration (isoemission or isobestic point) or, as a consequence, the linear dependence of Ie/[pyr] on Im/[pyr] can serve as a criterion of diffusion (fluidity)-controlled excimerization of pyrene. The isobestic point can be used for determining the range of working concentrations of the probe in membrane suspension. It was found from the intensity of pyrene fluorescence in the isobestic point and quenching with potassium iodide that at t < 30 degrees C, the probe is uniformly distributed throughout the membrane, and its excimerization is mainly controlled by the microviscosity of environment.

Artifacts↗
PubMedDate not supplied

The effect of humoral immunity against adducted benzo[a]pyrene on DNA damage elicited by acute carcinogen exposure in Swiss mice.

Immunoglobulins G (lgG) specific for benzo[a]pyrene-DNA adducts were elicited in Swiss mice by repeated subcutaneous injections of a high molecular weight benzo[a]pyrene-DNA conjugate-adjuvant mix. The immunization procedure resulted in the production of specific antibodies against adducted benzo[a]pyrene B[a]P in all treated animals. One week after completion of the immunization procedure, groups of ten immunized and ten non immunized female mice were treated by single intraperitoneal injection with two different doses of B[a]P. The mice were sacrificed 48 hours after treatment, and both liver and bone marrow cells were isolated for subsequent determinations of DNA binding and micronucleus induction, respectively. Covalent benzo[a]pyrene adducts in liver DNA were detected by competitive ELISA and the incidence of micronucleated polychromatic erythrocytes was evaluated by scoring one thousand cells per animal. The determination of DNA adducts in liver revealed significantly (p < 0.05) lower levels of B[a]P adducts in immunized mice compared to non-immunized animals at both doses, whereas no significant difference was observed between controls. Administration of benzo[a]pyrene produced moderate, dose-related increases in the incidence of micronucleated polychromatic erythrocytes in all treated groups, with no significant difference between immunized and non-immunized mice. The decrease of covalent DNA adducts in the liver of immunized mice suggests that the specific humoral immunity elicited by repeated carcinogen exposure may act as a relevant modulating factor in chemical carcinogenesis.

Animals↗
PubMed1992

A new functional role for P-glycoprotein: efflux pump for benzo(alpha)pyrene in human breast cancer MCF-7 cells.

We propose that the cellular burden of certain carcinogens may be mitigated by P-glycoprotein (P-gp), the putative drug efflux pump. In a series of multidrug resistant human breast cancer MCF-7 cells with increasing P-gp expression we examined this hypothesis using benzo(alpha)pyrene, a widely distributed environmental and dietary carcinogen. We found that multidrug resistant cells were cross-resistant to benzo(alpha)pyrene and the rates of efflux for benzo(alpha)pyrene were higher in multidrug resistant cells than in wild type cells. Evidence supporting the involvement of P-gp included the inhibition of azidopine binding to P-gp benzo(alpha)pyrene and the inhibition of benzo(alpha)pyrene efflux by Adriamycin and verapamil. Our findings suggest that P-gp may play a role in the cellular defense to carcinogens. The expression of P-gp and the modulation of its function may affect the susceptibility of normal tissues to transformation by carcinogens.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Phytoremediation for phenanthrene and pyrene contaminated soils.

Phytoremediation of soil contaminated with phenanthrene and pyrene was investigated using twelve plant species. Plant uptake and accumulation of these chemicals were evaluated. At the end of the experiment(45 d), the remaining respective concentrations of soil phenanthrene and pyrene in spiked vegetated soils, with initial phenanthrene of 133.3 mg/kg and pyrene of 171.5 mg/kg, were 8.71-16.4 and 44.9--65.0 mg/kg, generally 4.7%--49.4% and 7.1%--35.9% lower than their concentrations in the non-vegetated soils. The loss of phenanthrene and pyrene in vegetated spiked soils were 88.2%--93.0% and 62.3%--73.8% of the added amounts of these contaminants, respectively. Although plant uptake and accumulation of these compounds were evident, and root concentrations and RCFs (root concentration factors; defined as the ratio of PAH concentrations in roots and in the soils on a dry weight basis) of these compounds significantly positively correlated to root lipid contents, plant uptake and accumulation only accounted for less than 0.01% and 0.23% of the enhanced loss of these chemicals in vegetated versus non-vegetated soils. In contrast, plant-promoted microbial biodegradation was the dominant mechanism of the phytoremediation for soil phenanthrene and pyrene contamination. Results from this study suggested a feasibility of the establishment of phytoremediation for soil PAH contamination.

Biodegradation, Environmental↗