bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toxicity of wide-range polarity fractions from wood smoke and diesel exhaust particulate obtained using hot pressurized water
Authors: Kubátová Alena , Steckler Tamara S. , Gallagher John R. , Hawthorne Steven B. , Picklo Matthew J. 
Published: November 2004

Abstract
Epidemiological and toxicological studies correlate the adverse health effects of particulate matter (PM) with the available information regarding their chemical characterization, which has focused on nonpolar organics (e.g., polycyclic aromatic hydrocarbons [PAHs]), which are limited to 15 to 50% of total organic carbon. To study both polar and nonpolar species, we have employed hot pressurized (liquid) water for the fractionation of diesel exhaust and wood smoke PM. In agreement with the results of previous studies, nonpolar fractions from both PM samples showed strong cytotoxicity (cell viability decreased to 50–60%) corresponding to the presence of PAHs. Surprisingly, similar decreases in cell viability were also found in polar fractions (50°C) from both diesel exhaust and wood smoke PM. The midpolarity fractions (100−150°C) from wood smoke PM also displayed high cytotoxicity corresponding to methoxyphenols and oxy-PAHs. Although the midpolarity fractions from diesel exhaust PM showed no cytotoxicity, genotoxicity was found in the 150°C fraction, possibly corresponding to nitroaromatics. The present study demonstrates the suitability of hot pressurized water (as a single, nontoxic solvent) for the fractionation and toxicological characterization of wide-range polarity constituents of PM and, possibly, other environmental matrices.
Dynamic coupled metal transport-speciation model: Application to assess a zinc-contaminated lake
Authors: Bhavsar Satyendra P. , Diamond Miriam L. , Gandhi Nilima , Nilsen Joel 
Published: November 2004

Abstract
A coupled metal transport and speciation/complexation model (TRANSPEC) has been developed to estimate the speciation and fate of multiple interconverting species in surface aquatic systems. Dynamic-TRANSPEC loosely, sequentially couples the speciation/complexation and fate modules that, for the unsteady state formulation, run alternatively at every time step. The speciation module first estimates species abundance using, in this version, MINEQL+ considering time-dependent changes in water and pore-water chemistry. The fate module is based on the quantitative water air sediment interaction (QWASI) model and fugacity/aquivalence formulation, with the option of using a pseudo-steady state solution to account for past discharges. Similarly to the QWASI model for organic contaminants, TRANSPEC assumes the instantaneous equilibrium distribution of metal species among dissolved, colloidal, and particulate phases based on ambient chemistry parameters that can be collected through conventional field methods. The model is illustrated with its application to Ross Lake (Manitoba, Canada) that has elevated Zn concentrations due to discharges over 70 years from a mining operation. Using measurements from field studies, the model reproduces year-round variations in Zn water concentrations. A 10-year projection for current conditions suggests decreasing Zn remobilization and export from the lake. Decreasing Zn loadings increases sediment-to-water transport but decreases water concentrations, and vice versa. Species distribution is affected by pH such that a decrease in pH increases metal export from the lake and vice versa.
Induction of aryl hydrocarbon receptor–mediated and estrogen receptor–mediated activities, and modulation of cell proliferation by dinaphthofurans
Authors: Vondráček Jan , Chramostová Kateřina , Plíšková Martina , Bláha Luděk , Brack Werner , Kozubík Alois , Machala Miroslav 
Published: November 2004

Abstract
A group of heterocyclic aromatic compounds, dinaphthofurans (DNFs), recently have been identified as potentially significant contaminants in freshwater sediments. In the present study, a battery of in vitro assays was used for detection of toxic effects of DNFs that are potentially associated with endocrine disruption and tumor promotion. Dinaphthofurans were found to act as relatively potent inducers of aryl hydrocarbon receptor (AhR)–mediated activity in the chemical-activated luciferase reporter gene expression DR-CALUX assay. The relative AhR-inducing potencies of DNFs were similar or even higher than relative potencies of unsubstituted polycyclic aromatic hydrocarbons (PAHs), with dinaphtho[1,2-b;2′3′-d]furan being the most potent AhR agonist. Two compounds, dinaphtho[2,1-b;2′3′-d]furan and dinaphtho[1,2-b;1′2′-d]furan, induced estrogen receptor (ER)–mediated activity in the estrogen receptor–mediated CALUX (the ER-CALUX) assay. Two types of potential tumor-promoting effects of DNFs were investigated, using in vitro bioassays for detection of inhibition of gap-junctional intercellular communication and detection of a release from contact inhibition. Although the acute inhibition of gap-junctional intercellular communication was not observed, all six tested DNFs were able to release rat liver epithelial WB-F344 cells from contact inhibition at concentrations as low as 100 nM. In summary, the present study indicated that DNFs can exert multiple biological effects in vitro, including induction of the AhR-mediated activity, release of cells from contact inhibition, and induction of ER-mediated activity.
Development of a model microbial predator-prey system suitable for studies of the behavior of toxic trace metals
Authors: Patton Leslie E. , Shuler Michael L. , Lion Leonard W 
Published: November 2004

Abstract
Interactions between microbial predators and their prey cans significantly influence the behavior of toxic trace metals. Ingested bacterial prey—bound metals can either accumulate within a predator or be excreted and potentially reintroduced into the dissolved phase. A defined predator—prey system suitable for developing a more fundamental understanding of metal behavior in simple microbial food chains was designed and tested by using lead (Pb) as a representative cationic transition metal. Desired features of this system were the ability to define the chemical speciation of dissolved metals as well as to distinguish between prey- and predator-bound metals. Pseudomonas putida and the ciliate protozoan Tetrahymena thermophila were selected as representative bacterial prey and predator species, respectively. In addition, the use of fluorescent microspheres was evaluated as an experimental surrogate for bacterial prey. Filtration techniques for size-selective separation were developed so that the distribution of Pb between cells of T. thermophila, cells of P. putida or microspheres, and the dissolved phase could be assessed. Filtration units were selected based on their ability to perform separations with minimal metal loss at circumneutral pH. Five-micron polycarbonate filter membranes successfully separated T. thermophila from P. putida with good cell retention and low metal loss. Centrifuge filters successfully separated dissolved and particle-bound metal (&lt;5,000 nominal molecular wt limit). Exemplary experimental results are presented and show that predation on Pb-exposed cells of P. putida or microspheres increases uptake of Pb by T. thermophila.
Tributyltin uptake and depuration in Hyalella azteca: Implications for experimental design
Authors: Bartlett Adrienne J. , Borgmann Uwe , Dixon D. G Eorge , Atchelor Suzanne P. B , Maguire R. James 
Published: November 2004

Abstract
The purpose of this study was to address four aspects of the kinetics of tributyltin (TBT) in the freshwater amphipod Hyalella azteca: time to steady state, route of uptake, depuration rates, and effect of gut clearance. The amphipods accumulated TBT rapidly, reaching steady state within 14 d. Body concentrations were similar between caged and sediment-exposed animals, indicating that the primary route of uptake is via dissolved TBT. However, the rate of uptake was significantly higher in sediment-exposed amphipods. During depuration, body concentrations of TBT exhibited a biphasic decline, with a stronger decrease over the first 24 h that is attributed primarily to gut clearance, followed by a more gradual decrease most likely due to excretion from the body. Gut contents contributed significantly to body concentrations of TBT, accounting for 30% of the initial total body burden in sediment-exposed amphipods. Half-lives of TBT in gut-cleared H. azteca were 8 d and 14 d for amphipods exposed to spiked water and spiked sediment, respectively. The results of this study have significant implications in the experimental design and interpretation of studies involving the effects of TBT in H. azteca.
Metalloporphyrin solubility: A trigger for catalyzing reductive dechlorination of tetrachloroethylene
Authors: Dror Ishai , Schlautman Mark A. 
Published: November 2004

Abstract
Metalloporphyrins are well known for their electron-transfer roles in many natural redox systems. In addition, several metalloporphyrins and related tetrapyrrole macrocycles complexed with various core metals have been shown to catalyze the reductive dechlorination of certain organic compounds, thus demonstrating the potential for using naturally occurring metalloporphyrins to attenuate toxic and persistent chlorinated organic pollutants in the environment. However, despite the great interest in reductive dechlorination reactions and the wide variety of natural and synthetic porphyrins currently available, only soluble porphyrins, which comprise a small fraction of this particular family of organic macrocycles, have been used as electron-transfer shuttles in these reactions. Results from the present study clearly demonstrate that metalloporphyrin solubility is a key factor in their ability to catalyze the reductive dechlorination of tetrachloroethylene and its daughter compounds. Additionally, we show that certain insoluble and nonreactive metalloporphyrins can be activated as catalysts merely by changing solution conditions to bring about their dissolution. Furthermore, once a metalloporphyrin is fully dissolved and activated, tetrachloroethylene transformation proceeds rapidly, giving nonchlorinated and less toxic alkenes as the major reaction products. Results from the present study suggest that if the right environmental conditions exist or can be created, specific metalloporphyrins may provide a solution for cleaning up sites that are contaminated with chlorinated organic pollutants.
Uranium complexation and uptake by a green alga in relation to chemical speciation: The importance of the free uranyl ion
Authors: Fortin Claude , Dutels Laurent , Garnier-Laplace Jacqueline 
Published: November 2004

Abstract
The bioavailability and toxicity of dissolved metals are closely linked to the metals' chemical speciation in solution. Normally the complexation of a metal by a ligand would be expected to decrease its bioavailability. The aqueous speciation of uranium (U) undergoes tremendous changes in the presence of ligands commonly found in natural waters (carbonate, phosphate, hydroxide, and natural organic matter). In the present project, links between speciation, medium composition, and bioavailability of uranium toward Chlamydomonas reinhardtii, a unicellular green alga, were investigated. Short-term metal uptake rates were determined in simple inorganic media at constant low pH (5.0) and hardness with particular emphasis on the differentiation between adsorbed and intracellular metal. While intracellular uptake was fairly linear over 1 h, partly reversible adsorption reached steady-state within minutes. Both adsorption and absorption were saturable processes (with a half-saturation constant Km of 0.51 μM). Addition of phosphate, citrate, or ethylenediaminetetraacetic acid (EDTA) as ligands decreased uranium bioavailability. No evidence indicating the transport of intact uranyl complexes was found (i.e., facilitated diffusion of metal bound to an assimilable ligand such as uranium-phosphate complexes). Within these experimental conditions, uranium uptake was correlated with the free uranyl ion concentration as predicted by the free-ion activity model (FIAM) and biotic ligand model (BLM).
Interaction of tributyltin with hepatic cytochrome P450 and uridine diphosphate-glucuronosyl transferase systems of fish: In vitro studies
Authors: Morcillo Yolanda , Janer Gemma , O'Hara Sean C.M. , Livingstone David R. , Porte Cinta 
Published: November 2004

Abstract
Hepatic microsomes of red mullet (Mullus barbatus) and flounder (Platichthys flesus) were preincubated in the presence of a concentration range of the antifouling agent tributyltin (TBT) chloride, and the interactions of TBT with cytochrome P450 and uridine diphosphate—glucuronyl transferase systems were investigated. The enzyme systems were examined in terms of cytochrome P4501A (CYP1A)-catalyzed 7-ethoxyresorufin O-deethylase (EROD) activity and benzo[a]pyrene (BaP) metabolism and in terms of glucuronidation of testosterone and 17β-estradiol, respectively. Ethoxyresorufin O-deethylase and BaP hydroxylase (BPH) activities of both fish species were progressively inhibited by increasing concentrations of TBT, and the effects were more pronounced for EROD than for BPH (maximal inhibition at 100 μM TBT for EROD and 250–500 μM TBT for BPH). Hydroxylated metabolites of BaP (3-hydroxy-, 7,8-dihydrodiol, and 9,10-dihydrodiol), representing 95% of the total metabolites formed, were reduced up to 75 % in the presence of 100 to 500 μM TBT, whereas the formation of other metabolites was less affected. This may alter BaP toxicity and carcinogenicity. Overall, the results were consistent with a specific inhibitory effect of TBT on CYP1A in the two fish species. Additionally, the conjugation of testosterone was significantly inhibited (20%) at low TBT doses (5 μM), with no effect on the glucuronidation of estradiol.
Soil properties affecting toxicity of zinc to soil microbial properties in laboratory-spiked and field-contaminated soils
Authors: Smolders Erik , Buekers Jurgen , Oliver Ian , McLaughlin Mike J. 
Published: November 2004

Abstract
The effects of soil properties and zinc (Zn) availability on the toxicity of Zn to soil microbial processes are poorly understood. Three soil microbial processes—potential nitrification rate (PNR), substrate (glucose)-induced respiration (SIR), and a maize residue respiration (MRR)—were measured in 15 European topsoils (pH 3.0–7.5; total Zn 7–191 mg/kg) that were freshly spiked with ZnCl2. The Zn toxicity thresholds of 20 to 50% effective concentrations (EC20s and EC50s) based on total concentrations of Zn in soil varied between 5- and 26-fold among soils, depending on the assay. The Zn toxicity thresholds based on Zn concentrations in soil solution varied at least 10-fold more than corresponding total metal thresholds. Soil pH had no significant effect on soil total Zn toxicity thresholds, whereas significant positive correlations were found between these thresholds and background Zn for the PNR and SIR test (r = 0.74 and 0.71, respectively; log-log correlations). No such trend was found for the MRR test. Soil solution-based thresholds showed highly significant negative correlations with soil pH for all assays that might be explained by competition of H+ for binding sites, as demonstrated for aquatic species. The microbial assays were also applied to soils collected under galvanized pylons (three sites) where concentrations of total Zn were up to 2,100 to 3,700 mg Zn/kg. Correlations between concentrations of total Zn and microbial responses were insignificant at all sites even though spiking reference samples to equivalent concentrations reduced microbial activities up to more than 10-fold. Differences in response between spiked and field soils are partly but not completely attributed to the large differences in concentrations of Zn in soil solution. We conclude that soil pH has no significant effect on Zn toxicity to soil microbial processes in laboratory-spiked soils, and we suggest that community tolerance takes place at both background and elevated Zn concentrations in soil.
Responses of periphyton and invertebrates to a tetradecyl-pentadecyl sulfate mixture in stream mesocosms
Authors: Belanger Scott E. , Lee David M. , Bowling John W. , LeBlanc Ellen M. 
Published: November 2004

Abstract
Alkyl sulfates (AS) are anionic surfactants widely used in household and personal cleansing applications. Aquatic toxicity of AS under laboratory conditions indicated effects at relatively low concentrations (50–230 μg/L) for some sensitive species. A comprehensive stream mesocosm study of an AS mixture composed of tetra- (C14) and pentadecyl (C15) chain lengths was conducted to better understand effects on microbial and macroinvertebrate populations and communities. A 56-d exposure of AS was performed at concentrations ranging from 57 to 419 μg/L (analytically confirmed exposures) and was accompanied by detailed investigations of periphyton community function (autotrophy, heterotrophy, and metabolism of test chemical), periphyton structure (algal population and community dynamics based on taxonomic identity), and invertebrate structure (benthic abundance, drift, and insect emergence patterns based on taxonomic identity). A no-observed-effect-concentration (NOEC) of 222 μg/L was concluded for several individual algal and invertebrate species based on univariate statistical analyses. An apparent energetic subsidy from C14–15AS at the highest concentrations of 222 to 419 μg/L was observed and tied to changes in microbial community processing of AS when added at these high concentrations. A multivariate analysis based on principal response curves (PRC) indicated that communities in streams exposed to 222 to 419 μg/L were significantly different from the controls leading to an overall (multivariate and univariate) conclusion that 106 μg/L was the ecosystem NOEC. Exposure to AS in the environment has been demonstrated to be in the range of 5 to 21 μg/L in 100% wastewater treatment plant effluent. Potential environmental effects are at least 5 to 20 times above worst-case environmental exposures; therefore, C14–15AS does not pose a risk to the aquatic environment due to normal use patterns.
Degradation of metolachlor in bare and vegetated soils and in simulated water-sediment systems
Authors: Mersie Wondi , McNamee Clyde , Seybold Cathy , Wu Jigang , Tierney Dennis 
Published: November 2004

Abstract
A study was conducted to determine the half-life (t1/2), degradation rate, and metabolites of metolachlor in a water-sediment system and in soil with and without switchgrass. Metolachlor degradation in a laboratory was determined in sediment from Bojac sandy loam soil incubated at 24°C. The study also was conducted in a greenhouse on tilted beds filled with Bojac soil and planted with switchgrass. In both experiments, samples were collected at days 0, 7, 14, 28, 42, 56, and 112 and analyzed for metolachlor and its major metabolites. The water-sediment oxidation-reduction potential took 28 d to reach −371 mV and the pH increased from 5.6 to 6.5 by the last sampling day (day 112). The average soil temperature of the tilted beds with or without switchgrass during the study was 21°C and the soil moisture content was 23% by volume. The t1/2 of metolachlor was 34 d in sediment and 8 d in the water phase. The t1/2 of metolachlor in soil from the switchgrass filter strip (6 d) was not different from that in soil without grass (9.6 d). The metolachlor metabolites ethanesulfonic acid (ESA) and oxanilic acid (OA) were detected in the water-sediment system and in soil from tilted beds. In both sediment and soil from tilted beds, the two metabolites peaked by day 56 of incubation and declined after that, indicating transformation to other products. In the water-sediment system, greater quantities of OA and ESA were detected in sediment than in the aqueous phase. The production of OA and ESA in the water-sediment system occurred in the first 28 d, when the system was at an aerobic redox state. Metolachlor can degrade in sediment and the relatively high soil temperature and moisture level accelerated its breakdown in beds with and without switchgrass. Under warm and moist soil conditions, the presence of switchgrass has no effect on the degradation of metolachlor.
A survey of metals in tissues of farmed Atlantic and wild Pacific salmon
Authors: Foran Jeffery A. , Hites Ronald A. , Carpenter David O. , Hamilton M. Coreen , Mathews-Amos Amy , Schwager Steven J. 
Published: November 2004

Abstract
Contamination of fish tissues with organic and inorganic contaminants has been a pervasive environmental and public health problem. The present study reports the concentrations of nine metals in tissues of farmed Atlantic salmon (Salmo salar) and two species of wild-caught salmon (chum [Oncorhynchus keta] and coho [O. kisutch]) analyzed as part of a global survey of contaminants in these fish. Of the nine metals, organic arsenic was significantly higher in farmed than in wild salmon, whereas cobalt, copper, and cadmium were significantly higher in wild salmon. None of the contaminants exceeded federal standards or guidance levels.
Commissioning and initial validation of Eclipse eMC algorithm for the electron FLASH research extension (FLEX) system for pre‐clinical studies
Authors: Oh Kyuhak , Gallagher Kyle J. , Yan Ying , Zhou Sumin 
Published: February 2024

AbstractPurposeTo investigate the feasibility of commissioning the 16 MeV electron FLASH Extension (FLEX) in the commercial treatment planning system (TPS) for biomedical research with cell and mouse models, and in silico treatment planning studies.MethodsTo commission the FLEX system with the electron Monte Carlo (eMC) algorithm in the commercial TPS, radiochromic film was used to measure the vendor‐recommended beam data. Once the beam model was generated for the eMC algorithm, supplemental measurements were collected for validation purposes and compared against the TPS‐calculated results. Additionally, the newly commissioned 16 MeV FLASH beam was compared to the corresponding 16 MeV conventional electron beam.ResultsThe eMC algorithm effectively modeled the FLEX system. The eMC‐calculated PDDs and profiles for the 16 MeV electron FLASH beam agreed with measured values within 1%, on average, for 6 × 6 cm2 and 10 × 10 cm2 applicators. Flatness and symmetry deviated by less than 1%, while FWHM and penumbra agreed within 1 mm for both eMC‐calculated and measured profiles. Additionally, the small field (i.e., 2‐cm diameter cutout) that was measured for validation purposes agreed with TPS‐calculated results within 1%, on average, for both the PDD and profiles. The FLASH and conventional dose rate 16 MeV electron beam were in agreement in regard to energy, but the profiles for larger field sizes began to deviate (>10 × 10 cm2) due to the forward‐peaked nature of the FLASH beam. For cell irradiation experiments, the measured and eMC‐calculated in‐plane and cross‐plane absolute dose profiles agreed within 1%, on average.ConclusionsThe FLEX system was successfully commissioned in the commercial TPS using the eMC algorithm, which accurately modeled the forward‐peaked nature of the FLASH beam. A commissioned TPS for FLASH will be useful for pre‐clinical cell and animal studies, as well as in silico FLASH treatment planning studies for future clinical implementation.