Biomedical subjects

John L Newsted

Publications and source records attributed to John L Newsted.

At least 19 recordsLinked to original sources

PubMed2006

The H295R system for evaluation of endocrine-disrupting effects.

The present studies were undertaken to evaluate the utility of the H295R system as an in vitro assay to assess the potential of chemicals to modulate steroidogenesis. The effects of four model chemicals on the expression of ten steroidogenic genes and on the production of three steroid hormones were examined. Exposures with individual model chemicals as well as binary mixtures were conducted. Although the responses reflect the known mode of action of the various compounds, the results show that designating a chemical as "specific inducer or inhibitor" is unwise. Not all changes in the mixture exposures could be predicted based on results from individual chemical exposures. Hormone production was not always directly related to gene expression. The H295R system integrates the effects of direct-acting hormone agonists and antagonists as well as chemicals affecting signal transduction pathways for steroid production and provides data on both gene expression and hormone secretion which makes this cell line a valuable tool to examine effects of chemicals on steroidogenesis.

Aminoglutethimide↗

PubMed2006

Human adrenocarcinoma (H295R) cells for rapid in vitro determination of effects on steroidogenesis: hormone production.

To identify and prioritize chemicals that may alter steroidogenesis, an in vitro screening assay based on measuring alterations in hormone production was developed using the H295R human adrenocortical carcinoma cell line. Previous studies indicated that this cell line was useful to screen for effects on gene expression of steroidogenic enzymes. This study extended that work to measure the integrated response on production of testosterone (T), estradiol (E2), and progesterone/pregnenolone (P) using an ELISA. Under optimized culture and experimental conditions, the basal release of P, T and E2 into the medium was 7.0+/-1.2 ng/ml, 1.6+/-0.4 ng/ml, and 0.51+/-0.13 ng/ml, respectively. Model chemicals with different modes of action on steroidogenic systems were tested. Exposure to forskolin resulted in dose-dependent increases in all three hormones with the greatest relative increase being observed for E2. This differed from cells exposed to prochloraz or ketoconazole where P concentrations increased while T and E2 concentrations decreased in a dose-dependent manner. In cells exposed to fadrozole, E2 decreased in a dose-dependent manner while T and P only decreased at the greatest dose tested. Aminoglutethimide decreased P and E2 concentrations but increased T concentrations. Vinclozolin reduced both P and T but resulted in a slight increase in E2. The alteration in the patterns of hormone production in the H295R assay was consistent with the modes of action of the chemicals and was also consistent with observed effects of these chemicals in animal models. Based on these results, the H295R in vitro system has potential for high throughput screening to not only characterize the effects of chemicals on endocrine systems but also to prioritize chemicals for additional testing.

Adrenal Cortex↗

PubMed2006

Alteration of steroidogenesis in H295R cells by organic sediment contaminants and relationships to other endocrine disrupting effects.

A novel bioassay with the human adrenocortical carcinoma cell line H295R can be used to screen for endocrine disrupting chemicals that affect the expression of genes important in steroidogenesis. This assay was employed to study the effects of organic contaminants associated with the freshwater pond sediments collected in the Ostrava-Karvina region, Czech Republic. The modulation of ten major genes involved in the synthesis of steroid hormones (CYP11A, CYP11B2, CYP17, CYP19, 17betaHSD1, 17betaHSD4, CYP21, 3betaHSD2, HMGR, StAR) after exposure of H295R cells to sediment extracts was investigated using quantitative real-time polymerase chain reaction (PCR). Crude sediment extracts, containing high concentrations of polycyclic aromatic hydrocarbons (PAHs) and moderate amounts of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) significantly stimulated expression of the CYP11B2 gene (up to 10-fold induction), and suppressed expression of 3betaHSD2 and CYP21 genes. A similar pattern was observed with the extracts after treatment with concentrated sulfuric acid to remove labile chemicals (including PAHs) leaving only persistent PCBs, OCPs and potentially PCDD/Fs. Comparison of the results with other mechanistically based bioassays (arylhydrocarbon receptor, AhR, mediated responses in H4IIE-luc cells, and estrogen receptor mediated effects in MVLN cells) revealed significant endocrine disrupting potencies of organic contaminants present in the sediments (most likely antiestrogenicity). Pronounced effects were observed particularly in sediment extracts from the Pilnok Pond which harbors an unusual intersexual population of the narrow-cawed crayfish Pontastacus leptodactylus (Decapoda, Crustacea). This pilot study provided the first experimental evidence of the wider application of the H295R bioassay for screening complex environmental samples, and the results support the hypothesis of chemical-induced endocrine disruption in intersexual crayfish.

Cell Line, Tumor↗

PubMed2006

Pharmacokinetics and acute lethality of perfluorooctanesulfonate (PFOS) to juvenile mallard and northern bobwhite.

Ten-day-old mallards (Anas platyrhynchos) and northern bobwhite quail (Colinus virginianus) were fed perfluorooctanesulfonate (PFOS) in their diet for 5 days. The birds were then observed for 3 days while being given uncontaminated feed, and half of the birds were sacrificed on Day 8 of the trial. The remaining birds were maintained for an additional two weeks prior to being euthanized on Day 22 of the trial. Birds were assessed for growth, rate of feed consumption, behavior, physical injury, mortality, and gross abnormalities. Liver weight and concentrations of PFOS in blood serum and liver were also assessed. Based on the average daily intake (ADI) of PFOS calculated over the 5-day exposure period, the LD50 for juvenile mallards was determined to be 150 mg PFOS/kg body weight (bw)/day, equivalent to a total cumulative dose of 750 mg PFOS/kg bw calculated over a 5-day period. For juvenile quail, the LD50 based on the ADI was 61 mg PFOS/kg bw/day, equivalent to a total cumulative dose of 305 mg PFOS/kg bw. Reductions in weight gain and body weight were observed in quail from the 141 mg PFOS/kg treatment, but these measures returned to control levels by Day 22. The no-mortality dietary treatments were 70.3 and 141 mg PFOS/kg feed for quail and mallards, respectively. Both mallards and quail accumulated PFOS in blood serum and liver in a dose-dependent manner. The half-lives of PFOS in mallard blood serum and liver were estimated to be 6.86 and 17.5 days, respectively. In quail, the half-life of PFOS in liver was estimated to be 12.8 days, while the half-life of PFOS in quail blood serum could not be estimated. Concentrations of PFOS in juvenile mallard and quail liver associated with mortality are at least 50-fold greater than the single maximum PFOS concentration that has been measured in livers of avian wildlife.

Alkanesulfonic Acids↗

PubMed2006

Ecotoxicological evaluation of perfluorooctanesulfonate (PFOS).

Based on available toxicity data, protective screening-level concentrations of PFOS were calculated for aquatic and terrestrial organisms. Using the Great Lakes Initiative, water concentrations of PFOS were calculated to protect aquatic plants and animals. The screening plant value (SPV) protective of aquatic algae and macrophytes was calculated as 2.3 mg PFOS/L. The secondary chronic value protective of aquatic organisms was 1.2 microg PFOS/L. The screening-value water concentrations less than or equal to 1.2 microg PFOS/L would not pose a potential risk to aquatic organisms. Because the aquatic benchmark is based on the most sensitive species, this benchmark should also be protective of other aquatic organisms, including amphibians. The tissue-based TRV for fish was determined to be 87 mg PFOS/kg ww. For terrestrial plants, a screening benchmark was determined to be 1.3 mg PFOS/kg soil ww or 1.5 mg PFOS/kg soil dw, whereas for soil invertebrates such as earthworms the benchmark value was 39 mg PFOS/kg dw soil or 33 mg PFOS/kgww soil. For avian species, dietary, ADI, and egg yolk-based benchmarks were determined as 0.28mg PFOS/kg diet, 0.021mg PFOS/kg bw/d, and 1.7 microg PFOS/mL yolk, respectively. Benchmarks for serum and liver for the protection of avian species were 1.0 microg PFOS/mL and 0.6 microg PFOS/gww, respectively. However, no-effect levels in laboratory studies suggest actual population-level effects would not be expected to occur until a concentration of 6.0mg PFOS/kg in the diet, 5.0 microg PFOS/gww in the liver, or 9.0 microg PFOS/mL in the serum was exceeded, thus indicating the conservative nature of the benchmarks.

Alkanesulfonic Acids↗

PubMed2006

Productivity of tree swallows (Tachycineta bicolor) exposed to PCBs at the Kalamazoo River superfund site.

A 123-km stretch of the Kalamazoo River in Michigan, was designated a Superfund site in 1990 due to historical releases of effluent containing polychlorinated biphenyl (PCB)-contaminated paper waste. Risk to bird species in the river ecosystem was evaluated using the tree swallow (Tachycineta bicolor) as a monitor for possible effects due to PCB exposure at two nesting locations, one in the Superfund site and one in an upstream reference location that is less contaminated with PCBs. In 2 of the 3 years of the study, clutch size at the contaminated location was 3.7 +/- 1.4 and 4.8 +/- 0.73 eggs per nest (mean +/- SD), which was significantly less than the clutch size at the reference location (5.0 +/- 1.1 and 5.3 +/- 1.1 eggs per nest). However, there were no statistically significant differences in fledging success, predicted brood size, predicted number of fledglings, or growth of nestlings between the Kalamazoo River Superfund site and an upstream reference location with lesser concentrations of PCBs in the sediments and riparian soils. Productivity and hatching success comparisons between these same sites were also not significantly different; however, the power of these conclusions was less (p < .10). The reduction in clutch size at the co-contaminated location could not be attributed to PCBs due to a number of confounding factors, including Co-cocontaminants, habitat structure, and food availability. Other reproductive parameters were not significantly impaired, and the size of the newly established colony at the Kalamazoo River Superfund site continued to grow over the period of the study. These site-specific observations, combined with multiple lines of evidence approach that considered results reported for the effects of both total PCBs and 2,3,7,8 tetrachlorodibenzo-p-dioxin equivalents (TEQ) on tree swallows at other locations, suggest that there were no significant population-level effects of PCBs on tree swallows at the Kalamazoo River Superfund site.

Animals↗

PubMed2006

Tree swallow (Tachycineta bicolor) exposure to polychlorinated biphenyls at the Kalamazoo River superfund site, Michigan, USA.

In 1990, a portion of the Kalamazoo River in Michigan, USA, was designated a Superfund site because of the presence of polychlorinated biphenyls (PCBs) in the sediment and floodplain soils. During a four-year period from 2000 to 2003, several avian species were monitored for reproductive effects and concentrations of PCBs in tissues attributed to food chain transfer from contaminated sediments. The tree swallow (Tachycineta bicolor) was chosen as a model receptor for contamination of passerine species. A top-down methodology was used to evaluate the bioaccumulation of PCBs, including non-ortho and mono-ortho congeners, in tree swallow eggs, nestlings, and adults at the Kalamazoo River area of concern (KRAOC) and at an upstream reference site. Generally, a sixfold difference in tissue concentrations of total PCBs was observed between the two sites with concentrations in eggs and nestlings at the KRAOC ranging from 0.95 to 15 microg PCB/g wet weight. Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQsWHO Avian) for PCBs, based on bird-specific World Health Organization toxic equivalence factors, were 10- to 30-fold greater in the KRAOC than at the reference location. Egg and nestling TEQsWHO-Avian ranged from 0.21 to 2.4 ng TEQ/g wet weight at the KRAOC. Hazard quotients calculated from literature-derived toxicity reference values were below 1.0 at both the target and the reference site based on the no-observed-adverse-effect level and the lowest-observed-adverse-effect level.

Animals↗

PubMed2006

Accumulation of polychlorinated biphenyls from floodplain soils by passerine birds.

Eggs, nestlings, and adults of the eastern bluebird (Sialia sialis) and house wren (Troglodytes aedon) were collected at a polychlorinated biphenyl (PCB)-contaminated site and a reference location on the Kalamazoo River (MI, USA). Eggs and nestlings of eastern bluebirds at the more contaminated location contained concentrations of 8.3 and 1.3 mg/kg, respectively, of total PCBs and 77 and 6.3 ng/kg, respectively, of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs). Eggs, nestlings, and adults of house wrens from the contaminated location contained 6.3, 0.77, and 3.2 mg/kg, respectively, of PCBs and 400, 63, and 110 ng/kg, respectively, of TEQs. Concentrations of total PCBs and TEQs in tissues at the more contaminated location were significantly greater than concentrations in tissues at the reference site for all tissue types of both species. Exposures of the two species studied were different, which suggests that terrestrial-based insectivorous passerine species, foraging in the same area, may have differential exposure to PCBs depending on specific foraging techniques and the insect orders that are targeted. Despite the greater accumulation of PCBs at the more contaminated location, the risk of exposure to PCBs did not exceed the threshold for adverse effects at either location.

Animals↗

PubMed2006

Perfluorinated compounds in streams of the Shihwa Industrial Zone and Lake Shihwa, South Korea.

Concentrations of perfluorinated alkyl compounds (PFAs), including perfluorooctane sulfonate (PFOS), perfluorohexanesulfonate, perfluorobutanesulfonate, perfluorooctanesulfonamide, perfluorodecanoate, perfluorononanoic acid, perfluorooctanoate (PFOA), perfluoroheptanoate, and perfluorohexanoate, were measured in the streams of the Shihwa and Banweol industrial areas on the west coast of South Korea as well as the adjacent Lake Shihwa (an artificial lake) and Gyeonggi Bay. Perfluorinated alkyl compounds were concentrated from water using solid-phase extraction and were identified and quantified by liquid chromatography/ triple-quadrapole tandem mass spectrometry. Of the PFAs measured, PFOS and PFOA occurred at the greatest concentrations. Concentrations of PFOS ranged from 2.24 to 651 ng/L, and concentrations of PFOA ranged from 0.9 to 62 ng/L. The concentrations of PFOS observed in Lake Shihwa were among the greatest ever measured in the environment. These results suggest local industrial sources of PFOS and PFOA as well as other PFAs. Because of dilution, the greatest concentrations occur in a rather restricted area, near the points of discharge of the streams that empty into the lake. The greatest measured concentration of PFOS exceeded the threshold for effects predicted for predatory birds consuming aquatic organisms continuously exposed to this level.

Fluorocarbons↗

PubMed2005

Reproductive success of passerines exposed to polychlorinated biphenyls through the terrestrial food web of the Kalamazoo River.

The eastern bluebird (Sialia sialis) and the house wren (Troglodytes aedon) were identified as ecological receptors of concern due to exposure and potential effects stemming from polychlorinated biphenyl (PCB) contamination in floodplain soils of the Kalamazoo River Superfund Site, Michigan, USA. Measures of population health were compared at a contaminated and a less-contaminated reference location. During this 3-year study, productivity of bluebirds was significantly less at the downstream location than at the reference location. Hatching success, clutch size, and predicted brood size were significantly less in early clutches of house wrens at the more contaminated location than at the upstream reference location, but fledging success was significantly greater at the contaminated location. Studies concurrent to the study presented here reported that concentrations of PCBs in the tissues and diets of the passerine birds were less than the predicted threshold for adverse effects. The results of our study, taken along with the measured exposure data, suggest that other factors in addition to PCB exposure such as habitat, prey availability, small sample size, and cocontaminants were likely causes of the differences that were observed at the two locations.

Animals↗

PubMed2005

Avian toxicity reference values for perfluorooctane sulfonate.

Toxicity reference values (TRVs) and predicted no effect concentrations (PNECs) were derived for perfluorooctane sulfonate (PFOS) based on the characteristics of a top avian predator. On the basis of the protective assumptions used in this assessment, the benchmarks are protective of avian populations and were based on acute and chronic dietary exposures of northern bobwhite quail and mallard. Toxicological endpoints included mortality, growth, feed consumption, and histopathology. Reproductive endpoints included egg production, fertility, hatchability and survival, and growth of offspring. On the basis of the U. S. Environmental Protection Agency Great Lakes Initiative methodology, and a lowest observable adverse effect concentration (LOAEC) of 10 mg PFOS kg(-1) feed, an uncertainty factor of 36 was derived. The TRV based on PFOS dietary intake was 0.021 mg PFOS kg(-1) body weight day(-1), while for serum, liver, and egg, TRVs were 1.7 microg PFOS mL(-1), 0.6 microg PFOS g(-1) wet weight, and 1.7 microg PFOS mL(-1), respectively. On the basis of the European Commission methodology, a correction factor of 2 (for lowest observed effect level to no observable effect level) and an assessment factor of 30, for a total adjustment of 60, were used to derive PNECs. PNECs based on dietary, mean serum, liver, and egg PFOS concentrations were 0.013 mg PFOS kg(-1) body weight day(-1), 1.0 microg PFOS mL(-1), 0.35 microg PFOS g(-1) wet weight, and 1.0 microg PFOS mL(-1), respectively.

Alkanesulfonic Acids↗

PubMed2005

Differential accumulation of polychlorinated biphenyl congeners in the aquatic food web at the Kalamazoo River Superfund site, Michigan.

A series of field studies were conducted to gain a better understanding of the bioaccumulation and dynamics of polychlorinated biphenyl (PCB) congeners in the aquatic food web of the Kalamazoo River flood plain. Representative species of passerine birds, mammals, fish, aquatic plants, invertebrates, and colocated sediments were collected from areas located within submerged portions of the former Trowbridge impoundment and also from areas located at an upstream reference location. In most matrixes, total concentrations of PCBs were significantly greater in the downstream study area compared to the upstream reference location. Patterns of PCB congeners varied among trophic levels due to selective bioaccumulation of more chlorinated congeners in upper trophic level organisms. There were no statistically significant differences in total PCB concentrations among sampling grids within either site or temporally among three sampling seasons between May and September. The greatest total PCB concentrations were detected in adult tree swallows (mean = 8.7 mg/kg wet weight (ww)) and fish (mean = 4.4 mg/ kg ww) collected from the former Trowbridge impoundment. Concentrations of total 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) were greatest in egg, nestling, and adult tree swallows collected from the former Trowbridge impoundment. There was not a significant correlation between concentrations of total PCBs and TEQs at either site in the mammalian or avian food webs. The relative potency of the mixture of PCBs, expressed as the ratio of TEQs to total PCBs, increased with trophic position in the avian and mammalian aquatic food webs located within the former Trowbridge impoundment.

Animals↗

PubMed2005

Differential accumulation of polychlorinated biphenyl congeners in the terrestrial food web of the Kalamazoo River Superfund site, Michigan.

A series of field studies was conducted to determine the bioaccumulation of polychlorinated biphenyl (PCB) congeners in the terrestrial food web of the Kalamazoo River flood plain. Samples included colocated soils, native plants likely to be consumed by wildlife, several taxa of terrestrial invertebrates, small mammals, passerine bird eggs, nestlings, and adults, and great horned owl plasma and eggs. Mean concentrations of total PCBs in samples from the former Trowbridge impoundment were 6.5 mg/kg dry weight for soils and 0.023, 0.13, 1.3, 1.3, 1.6, and 8.2 mg/kg wet weight for plants, small herbivorous mammals, depurated earthworms, shrews, great horned owl eggs, and house wren eggs, respectively. Historical data from the Kalamazoo River have reported Aroclor-equivalent total PCB concentrations in the terrestrial food web; however, the degree of environmental weathering of the parent PCB mixtures was unknown. In this study, earthworms and composite samples of coleoptera exhibited PCB congener patterns that were similar to patterns in colocated soils. However, in plants, less chlorinated PCBs (e.g., mono-, di-, tri-, and tetrachlorinated biphenyls) were predominant, and in small mammals, there was a notable enrichment of PCBs 153, 180, 138, 118, and 99. In general, concentrations of PCBs were lower in most biota than in soil from the Kalamazoo River Area of Concern (KRAOC) although there was a modest biomagnification of PCBs from lower trophic level biota to highertrophic levels. As a consequence of environmental weathering of PCBs in the terrestrial food web of the KRAOC, the relative potency of the PCBs (expressed as mg TEQs/kg PCBs) decreased from soil to most biota. While there was a general trend, as expected, in which concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) increased with total PCBs, this relationship was rather poor (R2 = 0.13). Taken together, these data suggest that the differential accumulation of PCB congeners in the terrestrial food web can be explained by congener-specific differences in bioavailability from soil, exposure pathways, and metabolic potential of each of the food web components.

Animals↗

PubMed2005

Quantitative RT-PCR methods for evaluating toxicant-induced effects on steroidogenesis using the H295R cell line.

Gene expression profiles show considerable promise for the evaluation of the toxic potential of environmental contaminants. For example, any alterations in the pathways of steroid synthesis or breakdown have the potential to Cause endocrine disruption. Therefore monitoring these pathways can provide information relative to a chemical's ability to impact endocrine function. One approach to monitoring these pathways has been to use a human adrenocortical carcinoma cell line (H295R) that expresses all the key enzymes necessary for steroidogenesis. In this study we have further developed these methods using accurate and specific quantification methods utilizing molecular beacon-based quantitative RT-PCR (Q-RT-PCR). The assay system was used to analyze the expression patterns of 11 steroidogenic genes in H295R cells. The expression of gene transcripts was measured using a real-time PCR system and quantified based on both a standard curve method using a dilution series of RNA standards and a comparative Ct method. To validate the optimized method, cells were exposed to specific and nonspecific model compounds (inducers and inhibitors of various steroidogenic enzymes) for gene expression profiling. Similar gene expression profiles were exhibited by cells treated with chemicals acting through common mechanisms of action. Overall, our findings demonstrated that the present assay can facilitate the development of compound-specific response profiles, and will provide a sensitive and integrative screen for the effects of chemicals on steroidogenesis.

Cell Line, Tumor↗

PubMed2005

Distribution of PCDDs and PCDFs in soils collected from the Denver Front Range--principal components analysis of diffuse dioxin sources.

BACKGROUND, AIMS AND SCOPE: The Rocky Mountain Arsenal (RMA) is a U.S. Army facility located northeast of Denver, Colorado that has been listed on the National Priorities List (NPL). It is currently being re-mediated under the authority of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and the Superfund Amendments and Reauthorization Act of 1986 (SARA). As part of the remediation activities at RMA, indications were found that a source of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) had existed on the RMA. As a result, investigations were undertaken to assess the possible nature and extent of any potential sources of PCDDs and PCDFs on the RMA site. In addition, other studies were conducted that examined PCDD/PCDF contamination in the Denver area. The goal of these studies was to examine nature and extent of PCDD/PCDF contamination both on the RMA as well as in the surrounding Denver area. The intent of this study was to characterize sources of dioxins (PCDDs) and dibenzofurans (PCDFs) at low environmental concentrations which might have originated from diffuse sources in the Denver Colorado area and in particular, the Rocky Mountain Arsenal (RMA) using Principal Component Analysis (PCA). METHODS: Over 200 soil samples were collected from the RMA and the Denver area. From the RMA, soil was collected as part of three studies that included a (1) random site-wide sampling of the RMA, (2) soils from the Western Tier Parcel (WTP), and (3) soils from Historic Use areas. Denver area soil samples were collected from five different land use categories: Residential, Agricultural, Open Space, Commercial, and Industrial. PCA was conducted on concentrations of 17 2,3,7,8-substituted PCDD and PCDF congeners in 220 soil samples collected from the RMA and the Denver Front Range region. RESULTS AND DISCUSSION: PCA demonstrated the presence of possible minor sources of dioxins on the RMA. Current remediation efforts on RMA will result in the removal of these sources. Samples from the RMA were identified by the presence of a congener profile containing higher chlorinated PCDFs while the Denver Front Range areas were characterized by the presence of higher chlorinated PCDD congeners. The presence of a PCDF signature for the RMA samples does not necessarily indicate a major source of these contaminants on-site. Indeed, the relatively diffuse nature of the sample clusters would argue strongly against the presence of a single large source. Instead, the predominance of the PCDF congeners probably indicates the mixed industrial activities that took place on and near the site. CONCLUSION: PCA results indicate that PCDD/PCDF profiles in soils collected from the RMA differed from those collected from the outlying Denver areas but that a major source of these contaminants was not present. Rather, the diffuse nature of sample clusters from the PCA indicated that the congener profile of RMA samples was most likely a result of the mixed industrial activities that historically have taken place on and near the site. PCA also indicated that many of the 'open area' (peripheral site-wide) RMA soils samples did not differ from Denver are reference congener profiles. This finding was also true for samples collected from the WTP that were essentially indistinguishable from Off-RMA reference samples. In addition, total TEQ concentrations in soils collected from WTP were similar to those measured in soils collected from the Denver Front Range areas indicating that lack of a major source of PCDD/PCDF within the WTP zones of the RMA. RECOMMENDATION AND OUTLOOK: Analytical as well as statistical results of the soil congener data indicate that the WTP soils are indistinguishable from soils collected from non-industrial areas in the Denver area. This finding would support the recent 'de-listing' of the WTP from the other RMA areas and its transfer to other authorities in the Denver area.

Benzofurans↗

PubMed2004

Assessment of the effects of chemicals on the expression of ten steroidogenic genes in the H295R cell line using real-time PCR.

The potential for a variety of environmental contaminants to disturb endocrine function in wildlife and humans has been of recent concern. While much effort is being focused on the assessment of effects mediated through steroid hormone receptor-based mechanisms, there are potentially several other mechanisms that could lead to endocrine disruption. Recent studies have demonstrated that a variety of xenobiotics can alter the gene expression or activity of enzymes involved in steroidogenesis. By altering the production or catalytic activity of steroidogenic or steroid-catabolizing enzymes, these chemicals have the potential to alter the steroid balance in organisms. To assess the potential of chemicals to alter steroidogenesis, an assay system was developed using a human adrenocortical carcinoma cell line, the H295R cell line, which retains the ability to synthesize most of the important steroidogenic enzymes. Methods were developed, optimized, and validated to measure the expression of 10 genes involved in steroidogenesis by the use of real-time quantitative reverse transcriptase PCR. The effects of several model chemicals known to alter steroid metabolism, both inducers and inhibitors, were assessed. Similar expression patterns were observed for chemicals acting through common mechanisms of action. Time-course studies demonstrated distinct time-dependent expression profiles for chemicals able to modulate steroid metabolism. The assay, which allows simultaneous analysis of the expression of numerous steroidogenic enzymes, would be useful as a sensitive and integrative screen for the many effects of chemicals on steroidogenesis.

Adrenal Cortex↗

PubMed2004

Effect of light, temperature, and pH on the accumulation of phenol by Selenastrum capricornutum, a green alga.

The role of light, temperature, and pH was evaluated on the accumulation of phenol by the green alga, Selenastrum capricornutum. All three environmental variables had a significant effect on the accumulation of phenol. Differences in phenol accumulation were observed in algae that were cultured under light or dark conditions. In the light tests, the accumulation of phenol over a temperature range of 12-28 degrees C was unimodal while in the dark test accumulation exhibited a monotonic relationship with temperature. Differences in accumulation were not simply a function of algal growth or biomass. A unimodal relationship was also observed in the pH experiments with the maximal phenol accumulation in algae occurring at pH 6 and the least at pH 10. Temperature also influenced the accumulation of phenol by algae in the pH tests. As was determined in the light tests, biomass or cell growth was not a significant factor in determining the extent of accumulation in these studies. The results from this study demonstrate that accumulation of organics by algae is not simply a partitioning process but one that can be influenced by the interaction of biotic and abiotic variables.

Analysis of Variance↗

PubMed2003

Binding of perfluorinated fatty acids to serum proteins.

Perfluorooctane sulfonic acid (PFOS) accumulates in the liver and blood of exposed organisms. The potential for these surfactant molecules to interfere with hormone/protein interactions in blood is of concern given the importance of these interactions. The PFOS binding to serum proteins was investigated by assessing its ability to displace a variety of steroid hormones from specific binding proteins in the serum of birds and fishes. Perfluorooctane sulfonic acid had only a weak ability to displace estrogen or testosterone from carp serum steroid binding proteins. Displacement of cortisone in avian sera occurred at relatively low PFOS concentrations. Corticosterone displacement potency increased with chain length, and sulfonic acids were more potent than carboxylic acids. The PFOS concentrations estimated to cause these effects were 320 microM or greater, equivalent to serum concentrations greater than 160 mg/L. Using mass spectrometry and direct in vitro binding assays, PFOS was demonstrated to bind strongly to bovine serum albumin (BSA) in a 1:1 stoichiometric ratio. It appears that PFOS in serum is in general bound to albumins. Concentrations of PFOS required to saturate albumin would be in excess of 50 to 100 mg/L. Based on current environmental concentrations, it is unlikely that PFOS would cause displacement of hormones from serum proteins in wildlife.

Alkanesulfonic Acids↗