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PAH
Terms modified by PAH Selected AbstractsForce-Free Patterning of Polyelectrolyte Multilayers under Solvent AssistanceMACROMOLECULAR MATERIALS & ENGINEERING, Issue 8 2010Lulu Han Abstract Physical patterns were created on hydrated PSS/PDADMAC multilayers without using external force. A typical process was to put a PDMS stamp onto the wet and swollen multilayers, which were then put into an oven and maintained for a period of time to micromold the multilayers. The influence of molding temperature and time, multilayer thickness, solvent quality, and multilayer compositions on pattern formation were elucidated. Evolution of the patterns from double lines, double strips, and meniscus-shaped ridges to high ridges was observed under all conditions, revealing that this is a universal principle for this process. Finally, patterns on PAA/PAH and PSS/PAH multilayers were also prepared at the optimal conditions, highlighting its wide generality on the multilayer patterning. [source] Patterning of diverse mammalian cell types in serum free medium with photoablationBIOTECHNOLOGY PROGRESS, Issue 2 2009Vipra Dhir Abstract Integration of living cells with novel microdevices requires the development of innovative technologies for manipulating cells. Chemical surface patterning has been proven as an effective method to control the attachment and growth of diverse cell populations. Patterning polyelectrolyte multilayers through the combination of layer-by-layer self-assembly technique and photolithography offer a simple, versatile, and silicon compatible approach that overcomes chemical surface patterning limitations, such as short-term stability and low-protein adsorption resistance. In this study, direct photolithographic patterning of two types of multilayers, PAA (poly acrylic acid)/PAAm (poly acryl amide) and PAA/PAH (poly allyl amine hydrochloride), were developed to pattern mammalian neuronal, skeletal, and cardiac muscle cells. For all studied cell types, PAA/PAAm multilayers behaved as a cytophobic surface, completely preventing cell attachment. In contrast, PAA/PAH multilayers have shown a cell-selective behavior, promoting the attachment and growth of neuronal cells (embryonic rat hippocampal and NG108-15 cells) to a greater extent, while providing little attachment for neonatal rat cardiac and skeletal muscle cells (C2C12 cell line). PAA/PAAm multilayer cellular patterns have also shown a remarkable protein adsorption resistance. Protein adsorption protocols commonly used for surface treatment in cell culture did not compromise the cell attachment inhibiting feature of the PAA/PAAm multilayer patterns. The combination of polyelectrolyte multilayer patterns with different adsorbed proteins could expand the applicability of this technology to cell types that require specific proteins either on the surface or in the medium for attachment or differentiation, and could not be patterned using the traditional methods. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Incorporation of Pulmonary Vascular Resistance Measurement into Standard Echocardiography: Implications for Assessment of Pulmonary HypertensionECHOCARDIOGRAPHY, Issue 10 2007Kimberly B. Ulett B.S Doppler estimation of pulmonary artery systolic pressure (PASP) from tricuspid regurgitation velocity is a simple approach to the detection of pulmonary hypertension but may be influenced by right ventricular stroke volume. We sought the clinical utility of incorporating Doppler calculation of pulmonary vascular resistance (PVR) into determination of pulmonary hypertension in 578 consecutive patients with tricuspid regurgitation. Right atrial pressure was estimated from vena caval dimensions and collapsibility. Pulmonary hypertension was classified on the basis of a) PASP >35mmHg, b) age-/gender normalized PASP, c) PVR >2 Wood units. The mean PASP was 40 ± 13 mmHg and PVR was 1.9 ± 0.8 Wood units. Standard PASP identified pulmonary hypertension in 58%, compared with 36% by age-/gender normalized PASP (P < 0.0001), and 31% by PVR (P < 0.0001). Of patients who had pulmonary hypertension by PASP, 33% were reclassified as normal on the basis of PVR and 6% were reclassified from normal to pulmonary hypertension. PVR is easy to incorporate into a standard echo exam, and identifies a small group with normal PASP as having PAH, and a larger group of apparently increased PASP as normal. [source] Light-dependent mutagenesis by benzo[a]pyrene is mediated via oxidative DNA damageENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 3 2005Su-Ryang Kim Abstract Benzo[a]pyrene (B[a]P) is an environmental carcinogenic polycyclic aromatic hydrocarbon (PAH). Mammalian enzymes such as cytochrome P-450s and epoxide hydrase convert B[a]P to reactive metabolites that can covalently bind to DNA. However, some carcinogenic compounds that normally require metabolic activation can also be directly photoactivated to mutagens. To examine whether B[a]P is directly mutagenic in the presence of light, we exposed Salmonella typhimurium strains with different DNA repair capacities to B[a]P and white fluorescent light at wavelengths of 370,750 nm. B[a]P plus light significantly enhanced the number of His+ revertants. Mutagenesis was completely light-dependent and required no exogenous metabolic activation. The order of mutability of strains with different DNA repair capacities was strain YG3001 (uvrB, mutMST) , strain TA1535 (uvrB) > strain YG3002 (mutMST) > strain TA1975. The uvrB gene product is involved in the excision repair of bulky DNA adducts, and the mutMST gene encodes 8-oxoguanine (8-oxoG) DNA glycosylase, which removes 8-oxoG from DNA. Introduction of a plasmid carrying the mOgg1 gene that is the mouse counterpart of mutMST substantially reduced the light-mediated mutagenicity of B[a]P in strain YG3001. B[a]P plus light induced predominantly G:C , T:A and G:C , C:G transversions. We propose that B[a]P can directly induce bulky DNA adducts if light is present, and that the DNA adducts induce oxidative DNA damage, such as 8-oxoG, when exposed to light. These findings have implications for the photocarcinogenicity of PAHs. Environ. Mol. Mutagen., 2005. © 2005 Wiley-Liss, Inc. [source] Genotoxicity and physicochemical characteristics of traffic-related ambient particulate matterENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2005Theo M. de Kok Abstract Exposure to ambient particulate matter (PM) has been linked to several adverse health effects. Since vehicular traffic is a PM source of growing importance, we sampled total suspended particulate (TSP), PM10, and PM2.5 at six urban locations with pronounced differences in traffic intensity. The mutagenicity, DNA-adduct formation, and induction of oxidative DNA damage by the samples were studied as genotoxicological parameters, in relation to polycyclic aromatic hydrocarbon (PAH) levels, elemental composition, and radical-generating capacity (RGC) as chemical characteristics. We found pronounced differences in the genotoxicity and chemical characteristics of PM from the various locations, although we could not establish a correlation between traffic intensity and any of these characteristics for any of the PM size fractions. Therefore, the differences between locations may be due to local sources of PM, other than traffic. The concentration of total (carcinogenic) PAHs correlated positively with RGC, direct and S9-mediated mutagenicity, as well as the induction of DNA adducts and oxidative DNA damage. The interaction between total PAHs and transition metals correlated positively with DNA-adduct formation, particularly from the PM2.5 fraction. RGC was not associated with one specific PM size fraction, but mutagenicity and DNA reactivity after metabolic activation were relatively high in PM10 and PM2.5, when compared with TSP. We conclude that the toxicological characteristics of urban PM samples show pronounced differences, even when PM concentrations at the sample sites are comparable. This implies that emission reduction strategies that take chemical and toxicological characteristics of PM into account may be useful for reducing the health risks associated with PM exposure. Environ. Mol. Mutagen., 2005. © 2005 Wiley-Liss, Inc. [source] A new green fluorescent protein-based bacterial biosensor for analysing phenanthrene fluxesENVIRONMENTAL MICROBIOLOGY, Issue 4 2006Robin Tecon Summary The polycyclic aromatic hydrocarbon (PAH)-degrading strain Burkholderia sp. RP007 served as host strain for the design of a bacterial biosensor for the detection of phenanthrene. RP007 was transformed with a reporter plasmid containing a transcriptional fusion between the phnS putative promoter/operator region and the gene encoding the enhanced green fluorescent protein (GFP). The resulting bacterial biosensor ,Burkholderia sp. strain RP037 , produced significant amounts of GFP after batch incubation in the presence of phenanthrene crystals. Co-incubation with acetate did not disturb the phenanthrene-specific response but resulted in a homogenously responding population of cells. Active metabolism was required for induction with phenanthrene. The magnitude of GFP induction was influenced by physical parameters affecting the phenanthrene flux to the cells, such as the contact surface area between solid phenanthrene and the aqueous phase, addition of surfactant, and slow phenanthrene release from Model Polymer Release System beads or from a water-immiscible oil. These results strongly suggest that the bacterial biosensor can sense different phenanthrene fluxes while maintaining phenanthrene metabolism, thus acting as a genuine sensor for phenanthrene bioavailability. A relationship between GFP production and phenanthrene mass transfer is proposed. [source] Photochemical treatment of a mixed PAH/surfactant solution for surfactant recovery and reuseENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 4 2001Youn-Joo An Because of their hydrophobic nature, polycyclic aromatic hydrocarbons (PAHs) are generally thought to be unavailable to in situ remediation processes, and solubilization of PAHs by surfactants is usually recommended. However, mixed PAH/surfactant solutions are wastewaters that need a post-treatment after solubilization. In this study, mixed solutions of PAH and perfluorinated surfactant (PFS) were photochemically treated with and without hydrogen peroxide (H2O2), and the subsequent recovery and reuse of surfactant solutions were demonstrated. Phenanthrene and pyrene were selected as representative PAHs and lithium perfluorooctanesulfonate (LiFOS) as a PFS. Direct photolysis (UV only) and UV/H2O2 process enhanced the PAH degradation in LiFOS solutions compared to water. Both treatment processes selectively degraded PAHs without damaging PFS, suggesting that PFS withstands photolysis. Overall, it is demonstrated that UV and UV/H2O2 processes of mixed PAH/PFS solutions are effective for surfactant recovery/reuse, as well as PAH degradation. [source] Isolation and characterization of naphthalene-degrading bacteria from sediments of Cadiz area (SW Spain)ENVIRONMENTAL TOXICOLOGY, Issue 5 2008D. Nair Abstract Petroleum hydrocarbon contamination of harbor sediments from shipping activity, fuel oil spills, and runoffs are becoming a great concern because of the toxicity and recalcitrance of many of the fuel components. Polycyclic aromatic hydrocarbons (PAHs) are of most concern due to their toxicity, low volatility, resistance to degradation, and high affinity for sediments. Microorganisms, especially bacteria, play an important role in the biodegradation of these hydrocarbons. The objective of the present study was to characterize and isolate PAH-(naphthalene) degrading bacteria in the coastal sediments of Cadiz (SW Spain), since this area is mostly polluted by PAH occurrence. A total of 16 naphthalene-utilizing bacteria were isolated from these sites. Introduction of bacteria isolated from contaminated sediments into mineral medium contributed to the increased rate of hydrocarbon utilization. The bacterial isolates obtained from these sites are very potent in utilizing naphthalene and crude oil. It would be interesting to assess if the selected naphthalene-degrading isolates may degrade other compounds of similar structure. Hence these isolates could be very helpful in bioremediating the PAH-contaminated sites. Further pursue on this work might represent eco-friendly solution for oil contamination on sea surface and coastal area. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source] Uptake and elimination of hydrophobic organic contaminants in estuarine copepods: An experimental studyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2009Kévin Cailleaud Abstract Polycyclic aromatic hydrocarbons (PAHs) are considered to be rapidly biotransformed by organisms, whereas poly-chlorinated biphenyls (PCBs) are strongly bioaccumulated. In the present study, the estuarine copepod Eurytemora affinis was exposed in a continuous flow-through system to dissolved PAH (500 ng/L) and PCB (300 ng/L) mixtures for 86 h, whereas control groups were placed in a continuous flow-through system with clean water. Both PCB and PAH body residues were measured and compared in exposed and in nonexposed copepods to assess the uptake and the elimination of these two contaminant classes in this copepod species. After the exposure, exposed copepods exhibited concentration factors, based on a dry-weight basis, of 25, 750, and 1,200, respectively, for total PCBs and PAHs. The lower concentrations of PAHs in the nonexposed versus exposed copepods in contrast to small differences for PCBs suggest a higher rate of metabolism of PAHs compared with PCBs and could explain the differences observed in the accumulation. Furthermore, uptake as well as elimination of both PCBs and PAHs were compound selective in E. affinis. Therefore, higher-molecular-weight PCBs and PAHs were preferentially accumulated, while lower-molecular-weight compounds were preferentially eliminated. These results suggest the importance of copepods in the biogeochemical cycles of hydrophobic organic contaminants in estuarine ecosystems. [source] Vapor pressures and thermodynamics of oxygen-containing polycyclic aromatic hydrocarbons measured using knudsen effusion,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008Jillian L. Goldfarb Abstract Polycyclic aromatic hydrocarbons (PAHs) and their oxygenated derivatives (OPAHs) are ubiquitous environmental pollutants resulting from the incomplete combustion of coal and fossil fuels. Their vapor pressures are key thermodynamic data essential for modeling fate and transport within the environment. The present study involved nine PAHs containing oxygen heteroatoms, including aldehyde, carboxyl, and nitro groups, specifically 2-nitrofluorene, 9-fluorenecarboxylic acid, 2-fluorenecarboxaldehyde, 2-anthracenecarboxylic acid, 9-anthracenecarboxylic acid, 9-anthraldehyde, 1-nitropyrene, 1-pyrenecarboxaldehyde, and 1-bromo-2-naphthoic acid. The vapor pressures of these compounds, with molecular weights ranging from 194 to 251 g/mol, were measured using the isothermal Knudsen effusion technique in the temperature range of 329 to 421 K. The corresponding enthalpies of sublimation, calculated via the Clausius-Clapeyron equation, are compared to parent, nonoxygenated PAH compound data to determine the effect of the addition of these oxygen-containing heteroatoms. As expected, the addition of ,CHO, ,COOH, and ,NO2 groups onto these PAHs increases the enthalpy of sublimation and decreases the vapor pressure as compared to the parent PAH; the position of substitution also plays a significant role in determining the vapor pressure of these OPAHs. [source] Assessment of the toxicity of mixtures of nickel or cadmium with 9,10-phenanthrenequinone to Daphnia magna: Impact of a reactive oxygen-mediated mechanism with different redox-active metalsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2007Fangli Xie Abstract Recently, we showed that reactive oxygen species (ROS) formation was involved in the toxicity of the redox-active metal Cu and mixtures of Cu plus a photomodified polycyclic aromatic hydrocarbon (PAH), phenanthrenequinone (PHQ), to Daphnia magna. It is unknown, however, if similar results can be observed for metals with lower or no redox activity and their mixtures with PHQ. In the present study using D. magna, the toxicity of Ni, a weakly redox-active metal, and of Cd, a non-redox active metal, was examined with or without PHQ. The abilities of Ni, Cd, PHQ, and binary mixtures of metal plus PHQ to generate ROS were measured using a 2,,7,-dichlorofluorescein fluorescence assay. The results were compared with the results of Cu and mixtures of Cu plus PHQ from a recent study by our group. The order of metal toxicity to D. magna was found to be Cd , Cu > Ni. As with Cu/PHQ mixtures, synergistic toxicity was observed for mixtures of Ni and PHQ, whereas additive toxicity was observed for mixtures of Cd and PHQ. Alone, PHQ had no impact on ROS levels in D. magna. Nickel alone caused elevated ROS, which was further enhanced in the presence of PHQ. Neither Cd nor Cd/PHQ mixtures increased ROS production. Attenuation of toxicity and ROS production was observed in response to treatment with low concentrations of L -ascorbic acid. These results indicate potential toxic interactions between metals and modified PAHs. With redox-active metals, such as Cu and Ni, and modified PAHs, such as PHQ, these interactions can involve ROS formation. [source] Risk of weathered residual Exxon Valdez oil to pink salmon embryos in Prince William SoundENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2007Ernest L. Brannon Abstract It has been hypothesized that pink salmon eggs incubating in intertidal streams transecting Prince William Sound (PWS) beaches oiled by the Exxon Valdez oil spill were exposed to lethal doses of dissolved hydrocarbons. Since polycyclic aromatic hydrocarbon (PAH) levels in the incubation gravel were too low to cause mortality, the allegation is that dissolved high-molecular-weight hydrocarbons (HPAH) leaching from oil deposits on the beach adjacent to the streams were the source of toxicity. To evaluate this hypothesis, we placed pink salmon eggs in PWS beach sediments containing residual oil from the Exxon Valdez oil spill and in control areas without oil. We quantified the hydrocarbon concentrations in the eggs after three weeks of incubation. Tissue PAH concentrations of eggs in oiled sediments were generally <100 ppb and similar to background levels on nonoiled beaches. Even eggs in direct contact with oil in the sediment resulted in tissue PAH loads well below the lethal threshold concentrations established in laboratory bioassays, and very low concentrations of HPAH compounds were present. These results indicate that petroleum hydrocarbons dissolved from oil deposits on intertidal beaches are not at concentrations that pose toxic risk to incubating pink salmon eggs. The evidence does not support the hypothesis that interstitial pore water in previously oiled beaches is highly toxic. [source] Epifluorescence microscopy and image analysis of high-level polycyclic aromatic hydrocarbon contamination in soilsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2006J. Chadwick Roper Abstract Interactions between polycyclic aromatic hydrocarbons (PAHs) and soil are an important determinant of their chemical availability and transport. Laboratory examination of microscale PAH,soil interaction is limited by the availability of methods for particle-scale observation. Inverted epifluorescence microscopy, combined with digital photography and computer image analysis, was evaluated for specificity and linearity using dissolved PAHs. A pyrene filter (excitation wavelength, 360,400 nm; emission wavelength, 450,520 nm) gave nonspecific PAH fluorescence, and bias for fluoranthene, benzo[b]fluoranthene, benzo[g, h, i]perylene, and benz[a]anthracene was quantified in comparison to that for pyrene. Concentrations ranging from 1 to 10 mM for anthracene, fluoranthene, and pyrene and from 1 to 50 mM for naphthalene produced a linear response with low interpixel variability. Liquid-phase analyses validated use of the technique for the descriptive analysis of PAH distribution in solid samples, but liquid-phase calibration was not quantitative for spiked or field-contaminated soils. The mean luminance for three field soils was proportional to the values predicted from their chemically measured concentrations and to values from spiked, aged, uncontaminated materials. Image analysis of laboratory- and field-contaminated samples determined the area distribution of fluorescent intensity and the size of fluorescent areas exceeding a threshold luminance. These qualitative descriptions of the microscale spatial distribution of PAH contamination are presented as potential endpoints for future research on biogeochemical interactions in heavily contaminated solids. [source] Measured partitioning coefficients for parent and alkyl polycyclic aromatic hydrocarbons in 114 historically contaminated sediments: Part 1.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2006KOC values Abstract Polycyclic aromatic hydrocarbon (PAH) partitioning coefficients between sediment organic carbon and water (KOC) values were determined using 114 historically contaminated and background sediments collected from eight different rural and urban waterways in the northeastern United States. More than 2,100 individual KC values were measured in quadruplicate for PAHs ranging from two to six rings, along with the first reported KOC values for alkyl PAHs included in the U.S. Environmental Protection Agency's (U.S. EPA) sediment narcosis model for the prediction of PAH toxicity to benthic organisms. Sediment PAH concentrations ranged from 0.2 to 8,600 ,g/g (U.S. EPA 16 parent PAHs), but no observable trends in KOC values with concentration were observed for any of the individual PAHs. Literature KOC values that are commonly used for environmental modeling are similar to the lowest measured values for a particular PAH, with actual measured values typically ranging up to two orders of magnitude higher for both background and contaminated sediments. For example, the median log KOC values we determined for naphthalene, pyrene, and benzo[a]pyrene were 4.3, 5.8, and 6.7, respectively, compared to typical literature KOC values for the same PAHs of 2.9, 4.8, and 5.8, respectively. Our results clearly demonstrate that the common practice of using PAH KOC values derived from spiked sediments and modeled values based on n -octanol,water coefficients can greatly overestimate the actual partitioning of PAHs into water from field sediments. [source] Predicting single and mixture toxicity of petrogenic polycyclic aromatic hydrocarbons to the copepod Oithona davisaeENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2005Carlos Barata Abstract In the present study, the acute toxicity of 10 polycyclic aromatic hydrocarbons (PAH) associated with the Prestige fuel oil spill (Spain, 2002) were evaluated, either as single substances or in mixtures, in adults of the copepod Oithona davisae. All but dimethylphenanthrene had negative effects on O. davisae survival at concentrations below their water solubility, with 48-h median lethal concentrations for naphthalene and pyrene of 56.1 and 0.8 ,mol/L, respectively, making these the least and most toxic compounds. Polycyclic aromatic hydrocarbons had narcotic effects on copepods, as evidenced by the lack of motility at lower concentrations than those causing death. Naphthalene showed the greatest narcotic effects, and phenanthrene showed minor effects. Acute toxicity of the tested PAHs was inversely related (r2 = 0.9) with their octanol,water partition coefficient, thereby confirming the validity of the baseline quantitative structure,activity regression models for predicting the toxicity of PAH compounds in copepod species. When supplied in mixtures, the toxic effect of PAHs was additive. These results indicate that the many PAHs in an oil spill can be considered unambiguous baseline toxicants (class 1) acting additively as nonpolar narcotics in copepods; hence, their individual and combined toxicity can be predicted using their octanol,water partition coefficient. [source] Bench-scale evaluation of in situ bioremediation strategies for soil at a former manufactured gas plant siteENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2005Jun Li Abstract We examined the biodegradation and desorption of a set of 15 polycyclic aromatic hydrocarbon (PAH) compounds in coal tar,contaminated soil at a former manufactured gas plant site to evaluate the feasibility of in situ bioremediation. Experiments were conducted in well-mixed aerobic soil suspensions containing various additives over a 93- to 106-d period. In general, both biotransformation and desorption decreased with PAH ring size, becoming negligible for the six-ring PAH compounds. Biodegradation by indigenous microorganisms was strongly accelerated by addition of inorganic nutrients (N, P, K, and trace metals). The rates of biotransformation of PAH compounds by indigenous microorganisms in nutrient-amended flasks outpaced their maximum (i.e., chelate-enhanced) rates of desorption to an infinite sink (Tenax®) in sterilized systems run in parallel, suggesting that indigenous organisms facilitated desorption. Biodegradation by indigenous organisms in nutrient-amended flasks appeared to be unaffected by the addition of a site-derived bacterial enrichment culture, resulting in approximately 100-fold higher aromatic dioxygenase levels, and by the addition of 0.01 M chelating agent (citrate or pyrophosphate), although such chelating agents greatly enhanced desorption in microbially inactivated flasks. The strong ability of nutrients to enhance degradation of the bioavailable PAHs indicates that their persistence for many decades at this site likely results from nutrient-limited natural biodegradation, and it also suggests that an effective strategy for their bioremediation could consist simply of adding inorganic nutrients. [source] Effect of volatile hydrocarbon fractions on mobility and earthworm uptake of polycyclic aromatic hydrocarbons from soils and soil/lampblack mixturesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2005Bill W. Bogan Abstract Studies were conducted to examine the mobility and bioavailability to earthworms (Eisenia fetida) of priority pollutant polycyclic aromatic hydrocarbons (PAH) in a suite of 11 soils and soil/lampblack mixtures obtained from former manufactured-gas plant sites. Contaminant mobility was assessed using XAD4 resins encapsulated in dialysis tubing, which were exposed to slurried soils for 15 d. These experiments showed that mobility of PAH in the different soils strongly correlated to the levels of volatile hydrocarbons (namely, gasoline- and diesel-range organics [GRO and DRO]) that existed in the soils as co-contaminants. Actual PAH bioavailability (as measured by earthworm PAH concentrations) also appeared to depend on GRO + DRO levels, although this was most evident at high levels of these contaminants. These findings are discussed in view of the effects of diesel-range organics on oil viscosity, assuming that the hydrocarbon contaminants in these soils exist in the form of distinct adsorbed oil phases. This study, therefore, extends correlations between carrier-oil viscosity and dissolved solute bioavailability, previously observed in a number of other in vitro and whole-organism tests (and in bacterial mutagenicity studies in soil), to multicellular organisms inhabiting contaminated-soil systems. [source] Evaluation of the role of black carbon in attenuating bioaccumulation of polycyclic aromatic hydrocarbons from field-contaminated sediments,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2004Brita Sundelin Abstract The significance of black carbon (BC) for the bioavailability of polycyclic aromatic hydrocarbons (PAHs) was examined by using historically contaminated intact sediment cores in laboratory exposure experiments with the deposit-feeding amphipod Monoporeia affinis. Log values of amphipod biota,sediment accumulation factors (BSAFs) were significantly related to log BC, whereas log BSAFs were related to log octanol,water partition coefficients only in background sediments containing less BC. In the background sediments, the BSAF for polycyclic aromatic hydrocarbons (PAHs) was 1 to 2 for phenanthrene, with lower values for more hydrophobic PAHs, indicating an increase in nonequilibrium conditions with increasing PAH molecular size. For the near-equilibrated phenanthrene and fluoranthene, higher BSAFs were measured during exposure to background sediments, with BSAF decreasing to <0.1 in contaminated sediments in the Stockholm waterways. In situ caged mussels (Dreissena polymorpha) exhibited field BSAF values (relative to sediment-trap,collected suspended matter) for polychlorinated biphenyls (PCBs) of 0.1 to 0.4, but for PAHs of similar hydrophobicity and molecular size, the field BSAFs were much lower and in the range 0.002 to 0.05. This PAH,PCB dichotomy is consistent with recently reported much stronger binding to diesel soot (a form of BC) for PAHs than for PCBs of equal hydrophobicities. Lower BSAFs for the near-equilibrated PAHs (phenanthrene and fluoranthene) in the urban sediments relative to the background sediments were consistent with the larger presence of BC in the urban sediments. This study provides the first linked BSAF,BC field data that supports a causal relationship between strong soot sorption and reduced bioavailability for PAHs. [source] Tumor prevalence and biomarkers of exposure and response in brown bullhead (Ameiurus nebulosus) from the Anacostia River, Washington, DC and Tuckahoe River, Maryland, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2004Alfred E. Pinkney Abstract We valuated liver and skin tumor prevalence and biomarkers of exposure and response in brown bullhead (Ameiurus nebulosus) from three locations in the Anacostia River (Washington, DC, USA), a Chesapeake Bay region of concern. The Tuckahoe River (Maryland, USA) served as a reference. Each river was sampled in fall 2000 and spring 2001. In the Anacostia, prevalence of liver tumors was 50 to 68%, and prevalence of skin tumors was 13 to 23% in large (,260 mm, age ,3 years) bullheads. Liver and skin tumor prevalence was 10 to 17% and 0%, respectively, in small (150,225 mm, age 1,2 years) bullheads. Tuckahoe bullhead liver tumor prevalence was 0 to 3% (large) and 0% (small); none had skin tumors. Biliary polynuclear aromatic hydrocarbon (PAH)-like fluorescent metabolites and liver DNA adduct concentrations were elevated in large and small Anacostia bullheads. Mean adduct concentrations were 16 to 28 times higher than those in Tuckahoe fish. Chromatograms revealed a diagonal radioactive zone, indicating polycyclic aromatic compound (PAC)-DNA adducts. The biomarker data and the 10 to 17% liver tumor prevalence at ages 1 to 2 suggest that these year classes are likely to have a high prevalence as they reach age 3 and older. This study provides the strongest evidence to date of the role of PAHs in tumor development in Anacostia bullheads. [source] Influence of salinity on the bioaccumulation and photoinduced toxicity of fluoranthene to an estuarine shrimp and oligochaeteENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2003John E. Weinstein Abstract The effect of salinity on the photoinduced toxicity of waterborne fluoranthene to larvae of the grass shrimp (Palaemonetes pugto) and tubificid oligochaete worms (Monopylephorus rubrontveus) was studied in a laboratory system under simulated sunlight. In the grass shrimp toxicity tests, five concentrations of fluoranthene (0, 3.6, 7.3, 13.8, and 29.0 ,g/L) and four salinities (6.9, 14.5, 21.2, and 28.6,) were achieved. In the oligochaete toxicity tests, five concentrations of fluoranthene (0, 0.8, 1.4, 3.3, and 7.7 ,g/L) and four salinities (7.1, 13.3, 20.5, and 27.6,) were achieved. Salinity had no effect on either the photoinduced toxicity or the bioaccumulation of fluoranthene in the grass shrimp. However, the highest level of salinity decreased the median lethal time for the oligochaete. Bioaccumulation of fluoranthene was inversely related to salinity for the oligochaete. Additional experiments demonstrated an inverse relationship between salinity and short-term osmotic weight change in the oligochaete. Weight of the grass shrimp larvae was not affected by salinity. These findings show that salinity can influence the toxicity and bioaccumulation of fluoranthene in some estuarine organisms. The influence of salinity on these populations may be related to physiological responses associated with internal osmotic volume changes. Thus, salinity needs to be taken into account when assessing the risk of photoactivated polycyclic aromatic hydrocarbon (PAH) to at least some estuarine species. [source] Comparison of synthetic surfactants and biosurfactants in enhancing biodegradation of polycyclic aromatic hydrocarbonsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2003Randhir S. Makkar Abstract Polycyclic aromatic hydrocarbon (PAH) contamination of the environment represents a serious threat to the health of humans and ecosystems. Given the human health effects of PAHs, effective and cost-competitive remediation technologies are required. Bioremediation has shown promise as a potentially effective and low-cost treatment option, but concerns about the slow process rate and bioavailability limitations have hampered more widespread use of this technology. An option to enhance the bioavailability of PAHs is to add surfactants directly to soil in situ or ex situ in bioreactors. Surfactants increase the apparent solubility and desorption rate of the PAH to the aqueous phase. However, the results with some synthetic surfactants have shown that surfactant addition can actually inhibit PAH biodegradation via toxic interactions, stimulation of surfactant degraders, or sequestration of PAHs into surfactant micelles. Biosurfactants have been shown to have many of the positive effects of synthetic surfactants but without the drawbacks. They are biodegradable and nontoxic, and many biosurfactants do not produce true micelles, thus facilitating direct transfer of the surfactant-associated PAH to bacteria. The results with biosurfactants to date are promising, but further research to elucidate surfactant,PAH interactions in aqueous environments is needed to lead to predictive, mechanistic models of biosurfactant-enhanced PAH bioavailability and thus better bioremediation design. [source] A protocol to estimate the release of anthropogenic hydrocarbons from contaminated soilsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003Raymond C. Loehr Abstract An operational protocol, appropriate for a tier 1 or tier 2 type relative risk evaluation of a site that has polycyclic aromatic hydrocarbon (PAH) or petroleum hydrocarbon impacted soils, was developed to estimate the fraction of anthropogenic hydrophobic hydrocarbons that will be released rapidly from such soils. The development of this protocol used over 400 datasets from 40 different field samples to establish and verify the operational protocol. The datasets resulted from four-month kinetic desorption studies of these field samples. Based on the chemicals evaluated, the protocol has greatest application to two, three, and four ring-PAH and to diesel range aliphatic hydrocarbons. The protocol is a simple batch desorption analysis that uses established methods and is conducted for 7 d. The protocol results were verified with specific correlation relationships (r2 = 0.81 to 0.96) to estimate the rapidly releasing fraction (F value) that is obtained in a full, four-month chemical release evaluation. [source] Polycyclic aromatic hydrocarbon bioaccumulation by meiobenthic copepods inhabiting a superfund site: Techniques for micromass body burden and total lipid analysisENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2002Susan L. Klosterhaus Abstract Microtechniques for polycyclic aromatic hydrocarbon (PAH) body burden and total lipid analysis were developed and applied to determine the first lipid-normalized bioaccumulation factors for a hydrophobic organic toxicant in a meiobenthic organism (0.063-0.500 mm) living in field-contaminated sediments. The total lipid microtechnique combines the standard Bligh-Dyer extraction method with a colorimetric quantification method for analysis of samples containing 1 to 50 ,g lipid. The microtechnique for body burden analysis quantifies PAHs from tissue samples containing as little as 10 pg PAH. Fluoranthene, benz[a]anthracene, and benzo[a]pyrene biota-sediment accumulation factors (BSAFs) were determined for the meiobenthic copepod Microarthridion littorale living in an estuarine U.S. Environmental Protection Agency Superfund site. Gravid female, nongravid female, and male BSAFs were 0.82, 0.54, and 0.36, respectively, for fluoranthene; 0.50, 0.44, and 0.40, respectively, for benz[a]anthracene; and 0.09, 0.12, and 0.15, respectively, for benzo[a]pyrene. Comparison of nonlipid-normalized bioaccumulation factors (BAFs) to BSAFs indicates that M. littorale bioaccumulated PAHs on a gram lipid basis. The BSAFs declined consistently with increasing PAH log Kow for all copepod sex and reproductive stages. Sex- and stage-specific comparisons of BSAFs suggest that differences in lipid content and quality may lead to differences in BSAF values depending on PAH molecular weight and/or hydrophobicity. [source] A field validation of two sediment-amphipod toxicity testsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2002Steven P. Perraro Abstract A field validation study of two sediment-amphipod toxicity tests was conducted using sediment samples collected subtidally in the vicinity of a polycyclic aromatic hydrocarbon (PAH)-contaminated Superfund site in Elliott Bay (WA, USA). Sediment samples were collected at 30 stations with a 0.1 m2 grab from which subsamples were taken for sediment toxicity testing and geochemical and macrofaunal analyses. Standard 10-d sediment-amphipod toxicity tests were conducted with Rhepoxynius abronius and Leptocheirus plumulosus. Sediments were analyzed for 33 PAHs, pentachlorophenol, polychlorinated biphenyls, acid-volatile sulfide, simultaneously extracted metals (Cd, Cu, Zn, Pb, Ni), total organic carbon, and grain size. Sediment temperature, oxygen-reduction potential, water depth, and interstitial water salinity were also measured. Polycyclic aromatic hydrocarbons, quantified as total PAH toxic units (TUPAH), were confirmed to be an important common causal agent of the changes in the two toxicity test (% survival R. abronius, % survival L. plumulosus) and five macrofaunal community (number of species, S; numerical abundance, A; total biomass, B; Swartz's dominance index, SDI; Brillouin's index, H) endpoints. Two other macrofaunal community metrics (the complement of Simpson's index, 1 , SI, and McIntosh's index, MI) were less sensitive to TUPAH than the two toxicity test endpoints. The sensitivities of R. abronius and L. plumulosus to TUPAH were statistically indistinguishable. Field validations were conducted by testing the association between or among each toxicity test endpoint, each of seven macrofaunal community metrics (S, A, B, SDI, H, 1 , SI, MI), and TUPAH by (1) Spearman's coefficient of rank correlation, (2) Kendall's coefficient of concordance, (3) G tests of independence, and (4) regression analysis. Some field validations based on multivariable tests of association (e.g., points 2 and 3) among toxicity test, field, and stressor endpoints produced false positive results. Both toxicity test endpoints were validated as indicators of changes in S, A, SDI, and H by all the methods tested. The resolution power of the relationships between the laboratory toxicity test and macrofaunal field endpoints was low (, three classes) but sufficient to discriminate ecologically important effects. We conclude that standard sediment-amphipod toxicity tests are ecologically relevant and that, under the proper conditions, their results can be used for lab-to-field extrapolation. [source] Polycyclic aromatic hydrocarbons, aliphatic hydrocarbons, trace elements, and monooxygenase activity in birds nesting on the North Platte River, Casper, Wyoming, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2001Thomas W. Custer Abstract Tree swallow (Tachycineta bicolor) and house wren (Troglodytes aedon) eggs and chicks were collected near a refinery site on the North Platte River, Casper, Wyoming, USA and at a reference site 10 km upstream. Total polycyclic aromatic hydrocarbon (PAH) concentrations in swallow and wren chicks were higher at the refinery site than at the reference site. Polycyclic aromatic hydrocarbon concentrations in sediment and chick dietary samples were consistent with these findings. The general lack of methylated PAHs in sediment, diet, and bird carcasses suggested that the PAHs were derived from combustion and not from petroleum. The predominance of odd-numbered aliphatic hydrocarbons and the low ratios (,0.25) of pristane:n -C17 and phytane:n -C18 in chick and diet samples also suggested that swallow and wren chicks were not being chronically exposed to petroleum. Mean ethoxyresorufin- O -dealkylase and benzyloxyresorufin- O -dealkylase activities in tree swallow livers averaged nine times higher at the refinery site than at the reference site and were probably induced by exposure to PAHs. Trace element concentrations in eggs and livers of swallows and wrens were similar or greater at the reference site than at the refinery site. Selenium, strontium, and boron concentrations were elevated in eggs and livers of swallows and wrens at both the refinery and reference sites. [source] Pyrene and chrysene fate in surface soil and sand microcosmsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2001J. Chadwick Roper Abstract Polycyclic aromatic hydrocarbons (PAHs) are major components of wastes from municipal gas plants and many wood preservatives. Soil contaminated with these wastes is a potential threat to human health because of the carcinogenicity of many PAHs. This study follows the fate of two four-ring PAHs, pyrene and chrysene, in three matrices: an adapted soil (obtained from a site contaminated with PAHs for more than 75 years), an uncontaminated soil (with and without an inoculum of adapted soil), and sand mixed with an inoculum of adapted soil. Radiolabeled pyrene, chrysene, and salicylic acid (a metabolite of PAH biodegradation) were used to trace the mineralization, transformation, extractability, and formation of an unextractable residual over time. Linear approximations of the rates of these processes were made. High-performance liquid chromatography (HPLC) analysis of extracts from inoculated soil showed the transient formation of two known metabolites: 1-hydroxypyrene (from pyrene) and 1-hydroxy-2-naphthoic acid (from chrysene). The amount of extractable label diminished steadily over the course of the study in systems that were not inhibited with sodium azide, whereas the amount of extractable label remained relatively constant in inhibited systems. Correspondingly, the amount of nonextractable residual label generally increased during each incubation in uninhibited systems, whereas the amount of this residual label remained relatively constant in inhibited systems. In contrast, the rate and extent of mineralization varied widely across matrix types. This suggests that alterations of the PAH that impact extractability and residual formation are common, in contrast to mineralization, which was apparently limited to adapted communities. [source] Importance of maternal transfer of the photoreactive polycyclic aromatic hydrocarbon fluoranthene from benthic adult bivalves to their pelagic larvaeENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2000Marguerite C. Pelletier Abstract Laboratory experiments were conducted to determine if maternal transfer of polycyclicaromatichydrocarbons (P AH) from benthic adult bivalves could result in phototoxicity to their pelagic larvae when exposed to ultraviolet light (UV). In these experiments, adult bivalves were exposed to water or sediments amended with the model photoreactive PAH, fluoranthene. Elevated adult fluoranthene tissue concentrations were correlated with embryo concentrations. Embryonic mortality was enhanced by exposure to ultraviolet light when adult tissue fluoranthene levels were greater than 5,000 ,g/g lipid. While the exposure concentrations used in this experimental system were high, ultraviolet light exposure levels were low. Also, some of the PAHs are more potent than the model compound used in this study. These results indicate that maternal transfer of photoactive PAHs from organisms living in contaminated sediments may represent a significant adverse effect to populations of benthic bivalves. [source] Anthracene photoinduced toxicity to plhc-1 cell line (Poeciliopsis lucida) and the role of lipid peroxidation in toxicityENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2000Jonghoon Choi Abstract Many polycyclic aromatic hydrocarbons (PAHs) are acutely toxic to fish and other aquatic organisms in the presence of solar ultraviolet radiation (SUVR) of environmentally realistic intensities. In the present study, the photoinduced toxicity of a PAH (anthracene; ANT) to topminnow hepatoma cell line (PLHC-1) was assessed. After the toxicity was characterized, the role of lipid peroxidation in PAH photoinduced toxicity was examined by measuring lipid peroxidation products and by assessing the effect of lipid peroxidation antagonist (Trolox) treatment. In cytotoxicity tests using two assays (MTT, neutral red), the SUVR/ANT treatment elicited toxicity to PLHC-1 cells in a concentration- and SUVR (exposure duration and intensity)-dependent pattern. As found in previous organism-level studies, no significant cytotoxicity was observed in the cells exposed either to fluorescent light/ANT or to SUVR only. The SUVR/ANT treatment elicited the lipid peroxidation process and Trolox pretreatment significantly reduced SUVR/ANT-induced cell mortality. Microscopic observation showed that Trolox pretreatment relieved the SUVR/ANT-inflicted damage, such as cell shrinkage and membrane disruption. Together with a recent finding in our lab that increased production of superoxide anion and a lipid peroxidation product (malondialdehyde) was found in SUVR/ANT-treated fish microsomes, the present study suggests that reactive oxygen radical-induced lipid peroxidation is an important factor in PAH photoinduced toxicity to fish. [source] Evidence of oxidative stress in bluegill sunfish (Lepomis macrochirus) liver microsomes simultaneously exposed to solar ultraviolet radiation and anthraceneENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2000Jonghoon Choi Abstract Many polycyclic aromatic hydrocarbons (PAHs) are acutely toxic to fish and other aquatic organisms in the presence of environmentally realistic intensities of solar ultraviolet radiation (SUVR). However, the biochemical mechanism of this toxicity is not well established. In this study, increased levels of both reactive oxygen species production and lipid peroxidation were hypothesized as a toxic mechanism. To test this hypothesis, the production of superoxide anion and of a lipid peroxidation product (malondialdehyde) was measured in bluegill sunfish (Lepomis machrochirus) liver microsomes. These microsomes were exposed to a representative phototoxic PAH (anthracene [ANT]) and to SUVR and normal laboratory fluorescent light (FLU) in four different combinations: FLU + no ANT, FLU + ANT, SUVR + no ANT, and SUVR + ANT. The highest mean levels of both superoxide anion and malondialdehyde production were observed in the SUVR + ANT group, and these levels were significantly different (p < 0.05) from those in all other treatment groups. We conclude that the photoinduced toxicity of ANT, and possibly of other phototoxic PAHs, manifests at least in part through lipid peroxidation after increased production of reactive oxygen species. [source] The science of endothelin-1 and endothelin receptor antagonists in the management of pulmonary arterial hypertension: current understanding and future studiesEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2009N. J. Davie Abstract Pathological vascular remodelling is a key contributor to the symptomatology of pulmonary arterial hypertension (PAH), and reversing this process may offer the best hope for improving this debilitating condition. The vascular remodelling process is believed to be due to endothelial cell dysfunction and to involve altered production of endothelial cell-derived vasoactive mediators. The observation that circulating plasma levels of the vasoactive peptide endothelin (ET)-1 are raised in patients with PAH, and that ET-1 production is increased in the pulmonary tissue of affected individuals, makes it a particularly interesting target for a therapeutic intervention in PAH. Clinical trials with ET receptor antagonists (ETRAs) show that they provide symptomatic benefit in patients with PAH, thereby proving the clinical relevance of the ET system as a therapeutic target. In this paper, we review the role of ET-1 together with the available data on the roles of the specific ET receptors and ETRAs in PAH. In particular, we discuss the possible role of ET receptor selectivity in the vascular remodelling process in PAH and whether selective ETA or nonselective ETA/ETB blockade offers the greatest potential to improve symptoms and alter the clinical course of the disease. [source] | |||||||||||||||||||||||||||||||||||||||||||