bluuebunny/crossref_metadata_2025 huggingface dataset:
Increasing hCG concentrations during storage at +4°C with the Bayer Centaur Total hCG method
Authors: Page K , Gomez J , Smith N
Published: November 2004

Background: The interpretation of changes in serum human chorionic gonadotropin (hCG) concentrations in early pregnancy requires a knowledge of the day-to-day imprecision of the method at the concentrations measured. We therefore attempted to determine the analytical imprecision of our total hCG method over a 4-week period at concentrations up to 20 000 IU/L.

Methods: Serum specimens with hCG concentrations between 100 and 20 000 IU/L were collected during early pregnancy and analysed using the Bayer Centaur Total hCG method at weekly intervals after storage at +4°C and -20° C.

Results: The reproducibility of hCG results over a 4-week period in refrigerated specimens with an initial hCG concentration below 1000 IU/L was poor (mean coefficient of variation = 17.4%) and there was an apparent increase in serum hCG concentrations of up to 68%. Similar changes occurred in some specimens stored at -20°C. Further experiments confirmed that significant increases can occur during the first week following specimen collection.

Conclusions: Total hCG concentrations in serum specimens collected during early pregnancy increase significantly during storage when measured by the Bayer Centaur Total hCG method, possibly due to a conformational change in hyperglycosylated hCG. When this method is used for monitoring early pregnancy, specimens should ideally be analysed on the day of collection.
Multidimensional assessment of voice and speech after supracricoid laryngectomy with cricohyoidopexy
Authors: Yücetürk Ali Vefa , Günhan Kivanç
Published: November 2004

This study was designed: to evaluate the vocal function in the patients with supracricoid laryngectomy (SCL) compared with normal subjects; to determine the factors affecting voice (such as number of arytenoid(s) preserved and movement of larynx and tongue base); and to determine the correlations between videolaryngostroboscopy, acoustic and perceptual parameters.

Ten patients who underwent SCL with cricohyoidopexy for primary laryngeal squamous cell carcinoma were included into the study. Vocal function was investigated by means or videolaryngostroboscopy. Voice quality was assessed by means of objective acoustic analysis and subjective perceptual ratings by trained raters.

Aberrant, incompetent, and rough mucosal wave was observed in the anterior and superior surfaces of arytenoids(s), the inferior part of tongue base and the lateral walls of the hypopharynx. The acoustic parameters were found to be significantly different from those of normal subjects. The values of perceptual scores were approximately within 50 per cent of normal range. The number of arytenoids spared did not affect acoustic or perceptual measurements. A rough, breathy, unpleasant but intelligible and acceptable voice could be obtained after SCL with cricohyoidopexy.
Disaster avoided: otalgia warns of potential electrode extrusion
Authors: Tahery J. , Khan M.I.J. , Ramsden R.T.
Published: November 2004

Cochlear implantation is usually a safe procedure but, as in most surgical interventions, it can carry some risk of complications. These can be divided into major and minor that, in turn, in turn can present early or late. This case report highlights a potential late, major complication of cochlear implantation namely extrusion, which was averted by prompt intervention. The patient presented with a three months’ history of otalgia some six yearsafter successful implantation. The posterior half of the tympanic membrane was found to be retracted on the electrode, which appeared to be on the point of extruding through the drum. A tragal cartilage myringoplasty was performed to separate the electrode from the medial surface of the tympanic membrane. There was immediate and lasting relief of the otalgia, the electrode was well protected and performance with the device was unchanged.

The authors recommend reinforcing an atrophic tympanic membrane at the time of the cochlearimplantation by a cartilage graft to avoid this potentially serious complication. The case alsohighlights the need for regular otoscopy for all implanted patients.
Otoscopic appearances and tympanometric changes in narghile smokers
Authors: Effat Kamal G.
Published: November 2004

Narghile (water-pipe) smoking requires the generation of significant negative intrapharyngeal pressure, which may be transmitted to the middle ear through the Eustachian tube. A total of 80 ears from regular narghile smokers were examined otoscopically and by tympanometry. Seventy ears from heavy cigarette smokers were similarly examined and served as a control group. There was a highly significant increase in the prevalence of atticretractions (P < 0.01) in the narghile smokers. The tympanometric changes were not significantly different between the two groups (P > 0.05).
Is a doctor needed in the adult ENT pre–admission clinic?
Authors: Daniel M. , Banerjee A.R.
Published: November 2004

Objectives: Pre-admission clinics are traditionally run jointly by nurses and doctors. Within an adult ENT pre-admission clinic, we wished to assess what doctors added tonurses’ pre-clerking, to determine whether doctors were actually needed in the clinic.

Methods: Prospective study,looking at how often doctors, seeing patients after ward-based nurses, changed or added to clerking or tests as organized by nurses.

Results: Out of 184 patients, doctors changed or added to nurses’ clerking or planned investigations in 47 patients (26 per cent), making 64 different changes. The commonest reasonsfor changes were ordering blood tests (22 changes), chest X-rays (eight), cancelling due to hypertension (seven), altering drug history (five) and requesting electrocardiograms (five changes).

Conclusion: Most changes made by doctors could be eliminated by designing a
pre-admission clinic protocol that could easily be used by nurses. We recommend that all ENT departments consider implementing nurse-led pre-admission clinics.
Analysis of Gamma-Hydroxybutyric Acid (GHB) in Spiked Water and Beverage Samples Using Solid Phase Microextraction (SPME) on Fiber Derivatization/Gas Chromatography-Mass Spectrometry (GC/MS)
Authors: Meyers JE , Almirall JR
Published: November 2004

Gamma-Hydroxybutyric acid (GHB) is a CNS depressant that has been abused recreationally for its purported euphoric and relaxation effects and for the purposes of drug facilitated sexual assault due to its sedative and amnesic effects at higher doses. The dramatic increase in the abuse of GHB and association in criminal investigations over the past decade has created the need for forensic laboratories to develop analytical methods to detect GHB in a variety of matrices. The method developed in this work used solid-phase microextraction (SPME) to extract GHB from aqueous samples followed by on-fiber derivatization and analysis by gas chromatography/mass spectrometry (GC/MS). This method detected GHB in aqueous matrices with good sensitivity, high precision, excellent linearity from 0.01 mg/mL to 0.25 mg/mL, and without the need for sample manipulation that could cause interconversion between GHB and its lactone, GBL. The method was successfully applied for detection of GHB in spiked water and beverage samples.
Recognition of Cemetery Remains in A Forensic Context
Authors: Rogers TL
Published: November 2004

The purpose of this paper is to provide guidelines for the recognition of human remains from modern and historic cemeteries found in a forensic context. Three avenues of evidence may be pursued to confirm the origin of cemetery remains: context, condition of the body, and associated artifacts. This article outlines types of North American cemeteries, demonstrating how land use over time has resulted in many being closed, moved, or forgotten, leaving only the context to indicate their presence. The condition of human cemetery remains varies considerably depending on cultural practices and burial environment, but many exhibit combinations of the following traits: dried or embalmed tissue; erosion of bony pressure points; cortical bone flaking; and bone damage due to autopsy or embalming. Examples of artifact types useful in recognizing cemetery remains are also provided. Two cases from British Columbia, Canada are presented to demonstrate the diagnostic features of a disturbed cemetery burial.
Sudden Infant Death Syndrome Risk Factors with Regards to Sleep Position, Sleep Surface, and Co-Sleeping
Authors: Alexander RT , Radisch D
Published: November 2004

We present a study of 102 Sudden Infant Death Syndrome (SIDS) deaths using a retrospective review of medical examiner autopsy reports. The prevalence of sleep related risk factors with regards to sleep surface, sleep position, and co-sleeping were determined in a population of infants less than 1-year-old. Of the 102 SIDS deaths, 67 (65.7%) were not in a crib, 63 (61.8%) were prone, and 48 (47.1%) were co-sleeping. However, 94 (92.2%) of these deaths had at least one risk factor present. Only 8 (7.8%) infants had slept alone, in a crib or bassinet, and on their back or side. Infants less than 4-months-old had a higher rate of co-sleeping (54.7%) than the older infants (25.9%), and a higher frequency of heart malformations at post-mortem examination. The older infants were more likely to exhibit pulmonary and tracheal inflammation, and neuropathology.
Hyperostosis Frontalis Interna: Forensic Issues
Authors: Devriendt W , Piercecchi-Marti M-D , Adalian P , Sanvoisin A , Dutour O , Leonetti G
Published: November 2004

The use of pathological conditions in age and sex determination, important factors in personal identification, is not widespread in anthropology and legal medicine. Hyperostosis frontalis interna (HFI) is a bone condition that mainly affects the inner table of the frontal bone. Although there are numerous publications on the subject, at the present time its etiology remains obscure. Several associations of symptoms, whose incidence varies according to the population studied, have been described. Age and gender appear to be linked with the preponderance of this condition, as does the presence of behavioral disturbances. The aim of our study, based on a series of 1532 autopsies, was to define the incidence and the associations observed with other pathological conditions. Thirteen cases of HFI were identified (0.8% of autopsies), 12 women and one man whose mean age was 59.15 years (range: 42–79 years). All had behavioral disturbances and most were under psychiatric care. This study emphasizes the value of this condition in medico-legal identification.
Structure-activity relationship approaches and applications
Authors: Tong Weida , Welsh William J. , Shi Leming , Fang Hong , Perkins Roger
Published: November 2004

New techniques and software have enabled ubiquitous use of structure-activity relationships (SARs) in the pharmaceutical industry and toxicological sciences. We review the status of SAR technology by using examples to underscore the advances as well as the unique technical challenges. Applying SAR involves two steps: Characterization of the chemicals under investigation, and application of chemometric approaches to explore data patterns or to establish the relationships between structure and activity. We describe generally but not exhaustively the SAR methodologies popular use in toxicology, including representation of chemical structure, and chemometric techniques where models are both unsupervised and supervised. The utility of SAR technology is most evident when supervised methods are used to predict toxicity of untested chemicals based only on chemical structure. Such models can predict on both an ordinal scale (e.g., active vs inactive) or a continuous scale (e.g., median lethal dose [LD50] dose). The reader is also referred to a companion paper in this issue that discusses quantitative structure-activity relationship (QSAR) methods that have advanced markedly over the past decade.
Overview of data and conceptual approaches for derivation of quantitative structure-activity relationships for ecotoxicological effects of organic chemicals
Authors: Bradbury Steven P. , Russom Christine L. , Ankley Gerald T. , Schultz T. Wayne , Walker John D.
Published: November 2004

The use of quantitative structure-activity relationships (QSARs) in assessing potential toxic effects of organic chemicals on aquatic organisms continues to evolve as computational efficiency and toxicological understanding advance. With the ever-increasing production of new chemicals, and the need to optimize resources to assess thousands of existing chemicals in commerce, regulatory agencies have turned to QSARs as essential tools to help prioritize tiered risk assessments when empirical data are not available to evaluate toxicological effects. Progress in designing scientifically credible QSARs is intimately associated with the development of empirically derived databases of well-defined and quantified toxicity endpoints, which are based on a strategic evaluation of diverse sets of chemical structures, modes of toxic action, and species. This review provides a brief overview of four databases created for the purpose of developing QSARs for estimating toxicity of chemicals to aquatic organisms. The evolution of QSARs based initially on general chemical classification schemes, to models founded on modes of toxic action that range from nonspecific partitioning into hydrophobic cellular membranes to receptor-mediated mechanisms is summarized. Finally, an overview of expert systems that integrate chemical-specific mode of action classification and associated QSAR selection for estimating potential toxicological effects of organic chemicals is presented.
A review of quantitative structure-activity relationship methods for the prediction of atmospheric oxidation of organic chemicals
Authors: Meylan William M. , Howard Philip H.
Published: November 2004

Organic compounds are chemically transformed in the troposphere by reaction with photochemically generated oxidants that include hydroxyl radicals, nitrate radicals, and ozone. The reaction rates are a measure of atmospheric persistence and are necessary for developing environmental exposure assessments. Since relatively few experimentally measured rate constants are available, environmental risk/exposure assessors must estimate degradation rates. Rates can be predicted through use of quantitative structure-activity relationships (QSARs). QSAR methods are described for estimating reaction rates with hydroxyl radicals, nitrate radicals, and ozone. QSAR accuracy and limitations are also discussed.
Quantitative structure-activity relationships for predicting skin and respiratory sensitization
Authors: Rodford Rosemary , Patlewicz Grace , Walker John D. , Payne Martin P.
Published: November 2004

Quantitative structure-activity relationships (QSARs) for predicting skin and respiratory sensitization are reviewed. Overall, progress has been hampered by the sparseness of good quality experimental data, a fact that makes it difficult, at this time, to recommend one or two QSARs for predicting skin and respiratory sensitization. Creation of appropriate data sets for uninvestigated classes of chemicals by experimentation should facilitate the development of more robust QSARs for predicting skin and respiratory sensitization. Such QSARs will be valuable in the evaluation of identifiable toxic hazards where dose responses are relevant, as is the case for skin and respiratory sensitization.
Quantitative structure-activity relationships for predicting skin and eye irritation
Authors: Patlewicz Grace , Rodford Rosemary , Walker John D.
Published: November 2004

Recent quantitative structure-activity relationships (QSARs) for the prediction of skin and eye irritation were reviewed. The QSARs in these areas are hindered by the lack of quality in vivo data and by a lack of understanding of the mechanisms of action. Creation of appropriate data sets for experimentation would facilitate the development of robust QSARs for predicting skin and eye irritation.
Quantitative structure-activity relationships for predicting mutagenicity and carcinogenicity
Authors: Patlewicz Grace , Rodford Rosemary , Walker John D.
Published: November 2004

Quantitative structure-activity relationships (QSARs) for predicting mutagenicity and carcinogenicity were reviewed. The QSARs for predicting mutagenicity and carcinogenicity have been mostly limited to specific classes of chemicals (e.g., aromatic amines and heteroaromatic nitro chemicals). The motivation to develop QSARs for predicting mutagenicity and carcinogenicity to screen inventories of chemicals has produced four major commercially available computerized systems that are able to predict these endpoints: Deductive estimation of risk from existing knowledge (DEREK) toxicity prediction by komputer assisted technology (TOPKAT), computer automated structure evaluation (CASE), and multiple computer automated structure evaluation (Multicase). A brief overview of these and some other expert systems for predicting mutagenicity and carcinogenicity is provided. The other expert systems for predicting mutagenicity and carcinogenicity include automatic data analysis using pattern recognition techniques (ADAPT), QSAR Expert System (QSAR-ES), OncoLogic computer optimized molecular parametric analysis of chemical toxicity system (COMPACT), and common reactivity pattern (COREPA).
Guidelines for developing and using quantitative structure-activity relationships
Authors: Walker John D. , Jaworska Joanna , Comber Mike H. I. , Schultz T. Wayne , Dearden John C.
Published: November 2004

Numerous quantitative structure-activity relationships (QSARs) have been developed to predict properties, fate, and effects of mostly discrete organic chemicals. As the demand for different types of regulatory testing increases and the cost of experimental testing escalates, there is a need to evaluate the use of QSARs and provide some guidance to avoid their misuse, especially as QSARs are being considered for regulatory purposes. This paper provides some guidelines that will promote the proper development and use of QSARs. While this paper uses examples of QSARs to predict toxicity, the proposed guidelines are applicable to QSARs used to predict physical or chemical properties, environmental fate, ecological effects and health effects.
Mutagenicity of nitroaromatic degradation compounds
Authors: Padda Ranjit S. , Wang Chuanyue , Hughes Joseph B. , Kutty Razia , Bennett George N.
Published: November 2004

The mutagenicity of 2,4-dinitrotoluene (24DNT), and 2,6-dinitrotoluene (26DNT), and their related transformation products such as hydroxylamine and amine derivatives, which are formed by Clostridium acetobutylicum, were tested in crude cell extracts using Salmonella typhimurium TA100. A previous publication already reported the mutagenic activities of 2,4,6-trinitrotoluene (TNT) and its related hydroxylamine derivatives in this test system. A time course of the mutagenicity during the anaerobic transformation of TNT, 24DNT, and 26DNT was also investigated under the same conditions to compare with the results from the pure compounds. The monohydroxylamino intermediates 2-hydroxylamino-4-nitrotoluene (2HA4NT), 4-hydroxylamino-2-nitrotoluene (4HA2NT) and 2-hydroxylamino-6-nitrotoluene (2HA6NT) formed during anaerobic transformation of dinitrotoluenes were proven to be mutagenic in the Ames test using Salmonella typhimurium TA100. This study reports that 4HA2NT is the most stable derivative, whereas 2HA4NT and 2HA6NT are less stable and these intermediates are mutagenic in the Ames test. Both 24DNT and 26DNT and their final metabolites 2,4-diaminotoluene (24DAT) and 2,6-aminotoluene (26DAT) appeared nonmutagenic. In a time-course study of TNT degradation, the temporal sample containing 85% of 2,4-dihydroxylamino-6-nitrotoluene (24HA6NT) is most mutagenic. These observations suggest that the bioremediation approach for treatment of 24DNT and 26DNT should be carried past the hydroxylamino intermediate.
Effects of 4-nonylphenol on reproduction of japanese medaka, Oryzias latipes
Authors: Kang Ik Joon , Yokota Hirofumi , Oshima Yuji , Tsuruda Yukinari , Hano Takeshi , Maeda Masanobu , Imada Nobuyoshi , Tadokoro Hiroshi , Honjo Tsuneo
Published: November 2004

We exposed mature Japanese medaka (Oryzias latipes) to 4-nonylphenol (4-NP) to elucidate its reproductive effects and estrogenic responses. For each treatment, eight breeding pairs were exposed for 3 weeks at measured 4-NP concentrations of 24.8, 50.9, 101, and 184 μg/L. Egg production of the pairs during the third week of exposure (15–21 d) was significantly decreased in the ≥101-μg/L treatment group, and fertility was significantly decreased in the 184-μg/L group. Induction of testis–ova was observed in male fish at all 4-NP concentrations, whereas abnormality of spermatogenesis was found only in those receiving the 184-μg/L treatment. The gonadosomatic index of the males in the 184-μg/L group was also remarkably reduced. Hepatic vitellogenin (VTG) levels were significantly increased in both sexes receiving 4-NP treatments of ≥50.9 μg/L. Overall, the lowest-observed effective concentrations (LOECs) of 4-NP for decreasing reproductive capacity (fecundity and fertility) and eliciting estrogenic responses (induction of testis–ova and VTG) were 101 and ≤24.8 μg/L, respectively. The LOEC for reduced reproduction in medaka was at least four-fold greater than that required to elicit estrogenic responses in male fish. Thus, we suggest that the estrogenic responses expressed in male fish are not responsible for the reduction in reproductive capacity.
Chemical and biomonitoring to assess potential acute effects of Vision® herbicide on native amphibian larvae in forest wetlands
Authors: Thompson Dean G. , Wojtaszek Barbara F. , Staznik Bozena , Chartrand Derek T. , Stephenson Gerald R.
Published: November 2004

In conjunction with operational forest herbicide spray programs in Ontario, Canada, chemical and biological monitoring studies were conducted in 51 different wetlands to quantify the probability and magnitude of contamination by a glyphosate herbicide formulation (Vision®). Wetlands were classified as oversprayed, adjacent, or buffered in relation to the operational target spray blocks. Results show that vegetated buffers significantly mitigated against exposure and thus potential for acute effects. Aqueous concentrations of glyphosate in buffered wetlands were below analytical limits of quantitation (0.02 mg acid equivalent [a.e.]/L) in 14 of 16 cases, with mean concentration (0.03 ± 0.02 mg a.e./L) significantly (p < 0.05) less than that of either adjacent (0.18 ± 0.06 mg a.e./L) or oversprayed wetlands (0.33 ± 0.11 mg a.e./L). Biomonitoring with caged amphibian larvae showed no significant differences among mean mortality (48 h) of either Rana pipiens (p = 0.194) or Rana clamitans larvae (p = 0.129) exposed in situ to Vision under these various wetland conditions. Percent mortality was not significantly (p = 0.05) correlated with exposure concentrations for either amphibian species tested. Results suggest that exposures typically occurring in forest wetlands are insufficient to induce significant acute mortality in native amphibian larvae.
Phospholipase A2 activity in three species of littoral freshwater rotifers exposed to several toxicants
Authors: Pérez-Legaspi Ignacio Alejandro , Rico-Martínez Roberto
Published: November 2004

We analyzed three species of Lecane, a littoral rotifer, for susceptibility to six metals and four organic toxicants using a fluorometric assay based on inhibition of activity of the enzyme phospholipase A2. The metallic toxicants that we tested included Cd, Cr, Cu, Pb, Hg (as HgCl2), and Ti; the organic toxicants included benzene, ethyl acetate, toluene, and vinyl acetate. The three species differed greatly with respect to their susceptibility to the various toxicants. Lecane quadridentata, for example, was particularly sensitive to the four organic compounds (median effective concentration values [EC50] ranged from 6.6 × 10−4–0.987 mg/L). Lecane luna, in contrast, seemed particularly sensitive to metals (EC50 values ranged from 2 × 10−6–1.92 mg/L). Lecane hamata was relatively insensitive to organic solvents (EC50 values ranged from 4.25–126.5 mg/L).
A basin-specific aquatic food web biomagnification model for estimation of mercury target levels
Authors: Hope Bruce
Published: November 2004

In the Willamette River Basin (WRB, Oregon, USA), health advisories currently limit consumption of fish that have accumulated methylmercury (MeHg) to levels posing a potential health risk for humans. Under the Clean Water Act, these advisories create the requirement for a total maximum daily load (TMDL) for mercury in the WRB. A TMDL is a calculation of the maximum amount of a pollutant that a body of water can receive and still meet water-quality standards. Because MeHg is known to biomagnify in aquatic food webs, a basin-specific biomagnification factor can be used, given a protective fish tissue criterion, to estimate total mercury concentrations in surface waters required to lower advisory mercury concentrations currently in fish in the WRB. This paper presents an aquatic food web biomagnification model that simulates inorganic mercury (Hg(II)) and MeHg accumulation in fish tissue and estimates WRB-specific biomagnification factors for resident fish species of concern to stakeholders. Probabilistic (two-dimensional Monte Carlo) techniques propagate parameter variability and uncertainty throughout the model, providing decision makers with credible range information and increased flexibility in establishing a specific mercury target level. The model predicts the probability of tissue mercury concentrations in eight fish species within the range of concentrations measured in these species over 20 years of water-quality monitoring. Estimated mean biomagnification factor values range from 1.12 × 106 to 7.66 × 106 and are within the range of U.S. Environmental Protection Agency national values. Several WRB-specific mercury target levels are generated, which vary by their probability of affording human health protection relative to the federal MeHg tissue criterion of 0.30 mg/kg. Establishing a specific numeric target level is, however, a public policy decision, and one that will require further discussions among WRB stakeholders.
Biodegradation of 2-chlorophenol in forest soil: Effect of inoculation with aerobic sewage sludge
Authors: Lallai Antonio , Mura Giampaolo
Published: November 2004

Decontamination of 2-monochlorophenol-containing forest soil was studied in laboratory experiments. We found that in sterile soil, sorption of chlorophenol can occur. Chlorophenol disappearance of approximately 55% was observed in native soil; both soil sorption and degradation by indigenous soil populations caused this disappearance. In native soil, however, the rate of chlorophenol disappearance was enhanced up to slightly more than 90% by inoculation with a sludge taken from the aeration tank of a municipal wastewater treatment plant. In this sludge, the presence of Alcaligenes and Pseudomonas spp. was observed. In other experiments, addition to the soil of a laboratory culture preacclimated to 2-monochlorophenol did not lead to a greater increase in chlorophenol disappearance. In contrast to native soil, inoculation of sterile soil had no effect on disappearance of the chlorophenol. A possible explanation for the lack of cometabolic degradation is that autoclaving of the soil destroys the organic substances within it.
A toxicity identification evaluation approach to studying estrogenic substances in hog manure and agricultural runoff
Authors: Burnison B. Kent , Hartmann Andreas , Lister Andrea , Servos Mark R. , Ternes Thomas , Van Der Kraak Glen
Published: November 2004

Spreading liquid manure on agricultural fields is a routine way of disposing of animal manure and optimizing the use of nutrients for crops. Limited studies suggest that these wastes may contain a variety of endocrine-disrupting compounds (EDCs) that may be released into aquatic environments through runoff. The purpose of this study was to apply a toxicity identification and evaluation approach to isolate and identify estrogenic compounds in hog manure. A recombinant yeast estrogen screen bioassay was used to detect estrogenicity of high-performance liquid chromatography–separated hog manure fractions. Further analytical analyses of the fractions and comparison to authentic standards resulted in the identification of the endogenous estrogens 17β-estradiol (E2) and estrone, and the phytoestrogen metabolite, equol. High levels of equol (6.9–16.6 ppm) were found to be present in manure that was stored for several months. The endocrine-disrupting potential of equol was characterized further by using fish hormone estrogen receptor (ER), sex hormone binding protein (SSBP), and goldfish androgen receptor (AR) radioligand binding assays. Equol was found to be approximately 1,000- and 200-fold less potent that E2 in competing for binding sites of the SSBP and ER, respectively. Equol's potency was 2,200-fold less than testosterone for the AR. Additional studies confirmed the presence of compounds with estrogenic activity in tile drain water after application of hog manure to an agriculture field. In this case, the contribution of equol to the total estrogenicity of the tile drain water was minimal relative to that of natural estrogens. Overall, this study indicates that further work is warranted to assess the impact that EDCs that originate from agricultural runoff may have on the ecology or physiology of exposed biota.
Microbial degradation of chlorobenzene under oxygen-limited conditions leads to accumulation of 3-chlorocatechol
Authors: Vogt Carsten , Simon Dieter , Alfreider Albin , Babel Wolfgang
Published: November 2004

Five bacterial strains (Acidovorax facilis B517, Cellulomonas turbata B529, Pseudomonas veronii B547, Pseudomonas veronii B549, and Paenibacillus polymyxa B550) isolated on chlorobenzene as the sole source of carbon and energy were screened for the accumulation of the putative metabolic intermediate 3-chlorocatechol during growth on chlorobenzene under oxygen-limited conditions in the presence and absence of nitrate (1 mM). 3-Chlorocatechol accumulated in the growth media of all five strains, but accumulation was significantly less in cultures of A. facilis B517 compared to the other four strains. The presence of nitrate did not influence the biological conversion pattern. However, biologically produced nitrite reacted with 3-chlorocatechol chemically, a reaction that masked the accumulation of 3-chlorocatechol. For P. veronii B549, a clear relationship between the presence of 3-chlorocatechol in the medium and low oxygen concentrations was demonstrated. The assumption is made that accumulation of 3-chlorocatechol is due to the low enzymatic turnover of the 3-chlorocatechol cleaving enzyme, catechol-1,2-dioxygenase, at low oxygen concentrations.
Synthesis and estrogenic activity of bisphenol A mono- and di-β-D-glucopyranosides, plant metabolites of bisphenol A
Authors: Morohoshi Kaori , Shiraishi Fujio , Oshima Yukiko , Koda Tomoko , Nakajima Nobuyoshi , Edmonds John S. , Morita Masatoshi
Published: November 2004

The syntheses and characterization of bisphenol A mno- and di-β-D-glucopyranosides were undertaken to confirm that these compounds are major plant metabolites of bisphenol A (BPA) and to allow an assessment of their estrogenicity. Synthesis involved the glucosidation of unprotected BPA with glucose penta-acetate with phosphorus oxychloride as catalyst. The estrogenic activity of BPA and its mono- and di-β-D-glucopyranosides were measured with an enzyme-linked immunosorbent assay (ELISA)-based estrogen receptor competitive binding assay and with a yeast two-hybrid assay adapted to a chemiluminescent reporter gene (for β-galactosidase). Both methods showed that the estrogenicity of BPA was eliminated by formation of the diglucoside, but whereas the ELISA-based method indicated that reduced activity remained in the monoglucoside, the yeast two-hybrid method showed the monoglucoside to be inactive. Presumably these results reflect the more complex interactions of test compound and cellular components required to demonstrate estrogenicity in the yeast two-hybrid assay. As these processes parallel those in mammalian cells, the yeast two-hybrid method is likely to be the more realistic assay. The uptake and metabolism of BPA by plants offers the possibility of phytoremediation of contaminated water, but also provides an additional route for the compound to enter the human food chain.
Development and field validation of a predictive copper toxicity model for the green alga Pseudokirchneriella subcapitata
Authors: De Schamphelaere Karel A. C. , Vasconcelos Flavio M. , Heijerick Dagobert G. , Tack Filip M. G. , Delbeke Katrien , Allen Herbert E. , Janssen Colin R.
Published: November 2004

In this sudy, the combined effects of pH, water hardness, and dissolved organic carbon(DO) concentration and type on the chronic (72-h) effect of copper on growth inhibition of the green alga Pseudokirchneriella subcapitata were investigated. Natural dissolved organic matter (DOM) was collected at three sites in Belgium and The Netherlands using reverse osmosis. A full central composite test design was used for one DOM and a subset of the full design for the two other DOMs. For a total number of 35 toxicity tests performed, 72-h effect concentration resulting in 10% growth inhibition (EbC10s) ranged from 14.2 to 175.9 μg Cu/L (factor 12) and 72-h EbC50s from 26.9 to 506.8 μg Cu/L (factor 20). Statistical analysis demonstrated that DOC concentration, DOM type, and pH had a significant effect on copper toxicity; hardness did not affect toxicity at the levels tested. In general, an increase in pH resulted in increased toxicity, whereas an increase of the DOC concentration resulted in decreased copper toxicity. When expressed as dissolved copper, significant differences of toxicity reduction capacity were noted across the three DOM types tested (up to factor 2.5). When expressed as Cu2+ activity, effect levels were only significantly affected by pH; linear relationships were observed between pH and the logarithm of the effect concentrations expressed as free copper ion activity, that is, log(EbC50 Cu2+) and log(EbC10 Cu2+): (1) log(EbC50 Cu2+) = —1.431 pH + 2.050 (r2 = 0.95), and (2) log(EbC10 Cu2+) = —1.140 pH — 0.812 (r2 = 0.91). A copper toxicity model was developed by linking these equations to the WHAM V geochemical speciation model. This model predicted 97% of the EbC50dissolved and EbC10dissolved values within a factor of two of the observed values. Further validation using toxicity test results that were obtained previously with copper-spiked European surface waters demonstrated that for 81% of tested waters, effect concentrations were predicted within a factor of two of the observed. The developed model is considered to be an important step forward in accounting for copper bioavailability in natural systems.
A freshwater food web model for the combined effects of nutrients and insecticide stress and subsequent recovery
Authors: Traas Theo P. , Janse Jan H. , van den Brink Paul J. , Brock Theo C.M. , Aldenberg Tom
Published: November 2004

A microcosm experiment that addressed the interaction between eutrophication processes and contaminants was analyzed using a food web model. Both direct and indirect effects of nutrient additions and a single insecticide application (chlorpyrifos) on biomass dynamics and recovery of functional groups were modeled. Direct toxicant effects on sensitive arthropods could be predicted reasonably well using concentration-response relationships from the laboratory with representative species. Model predictions showed that nutrient additions alone caused only small effects on toxicant fate and effects probably due to the relatively high dissipation rate of chlorpyrifos. Enhancement of eutrophication effects by the insecticide was relatively small and seemed to be additive. The recovery of some affected functional groups was hampered in the indoor microcosms due to their isolation from outdoor seed populations. Introducing recolonization scenarios in the model simulated dose-dependent recovery. Recolonization increased the recovering rate after exposure to the pesticide. Modeling can extend the use of microcosms as a link between laboratory and field as this allows the prediction of effects and recovery of ecosystems for concentrations that have not been experimentally tested.
Modeling the influence of temporal and spatial factors on the assessment of impacts of pesticides on skylarks
Authors: Topping Christopher John , Odderskær Peter
Published: November 2004

Spatio-temporal factors strongly influence the population dynamics of animals; thus there have been calls to integrate these factors in environmental impact assessment of toxic compounds. To date, methodological difficulties have probably prevented this union. However, new modeling techniques that could help are available. This paper presents the construction and application of an agent-based simulation model of skylarks in agricultural landscapes and its use to assess the impact of pesticides relative to changes in landscape structure and mortality assumptions. Simulations indicated that pesticides had a negative impact on skylark population size. The annual reduction in numbers was variable and depended primarily upon migration mortality and an interaction between weather and pesticides. Altering landscape structure, crop diversity, or migration mortality assumptions resulted in a population change of approximately 37%, compared to a mean of 4% for pesticides. It was concluded that factors other than pesticides are likely to be limiting skylark numbers in most landscapes. This study demonstrates the importance of modeling the interactions between spatio-temporal environmental factors and the study organisms. Agent-based models (ABMs) are able to extract these relationships as emergent properties of their mechanistic nature. Therefore, we recommend the use of ABM models in future regulatory assessment of pesticides.
Quantitative cationic-activity relationships for predicting toxicity of metals
Authors: Walker John D. , Enache Monica , Dearden John C.
Published: November 2004

Developing and validating quantitative cationic-activity relationships or (Q)CARs to predict the toxicity metals is challenging because of issues associated with metal speciation, complexation and interactions within biological systems and the media used to study these interactions. However, a number of simplifying assumptions can be used to develop and validate (Q)CARs to predict the toxicity of metals: The ionic form is the most active form of a metal; the bioactivity of a dissolved metal is correlated with its free ion concentration or activity; most metals exist in biological systems as cations, and differences in metal toxicity result from differences in metal ion binding to biological molecules (ligand-binding). In summary, it appears that certain useful correlations can be made between several physical and chemical properties of ions (mostly cations) and toxicity of metals. This review provides a historical perspective of studies that have reported correlations between physical and chemical properties of cations and toxicity to mammalian and nonmammalian species using in vitro and in vivo assays. To prepare this review, approximately 100 contributions dating from 1839 to 2003 were evaluated and the relationships between about 20 physical and chemical properties of cations and their potential to produce toxic effects were examined.
Linear free-energy relationship analysis of the fate of chlorinated 1- and 2-carbon compounds by redox-manipulated smectite clay minerals
Authors: Cervini-Silva Javiera
Published: November 2004

This paper expands on earlier work on the effect of molecular structure on the fate of a series of chlorinated 1-and 2-carbon compounds (RCl), including carbon tetrachloride, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, trichloroethene, tetrachloroethene, trichloronitromethane, and trichloroacetonitrile, in the presence of unaltered (SWa-U) and reduced (SWa-R) ferruginous smectite. A linear free-energy relationships (LFERs) analysis was conducted to explain kinetic data for RCl adsorption and dechlorination. Correlation analyses based on RCl hydration energies, hydrolysis rate constants, or bond dissociation energies were significant (r2 > 0.87) for RCl adsorption by SWa-R but not so for RCl adsorption by SWa-U (r2 < 0.5). The most statistically significant relationships describing RCl kinetic data were achieved using multivariable regression analysis including RCl hydration energies (or hydrolysis rate constant) and bond dissociation energies for RCl heterolysis. The outcome of this study indicates that the oxidation state of structural Fe in the clay strongly influences RCl hydration. A mechanism consistent with the present LFERs analysis corresponds to RCl hydration as the limiting step for adsorption and dechlorination by redox-manipulated smectites.
Effects of dissolved organic carbon concentration and source, pH, and water hardness on chronic toxicity of copper to Daphnia magna
Authors: De Schamphelaere Karel A. C. , Janssen Colin R.
Published: November 2004

The effects of pH (5.3–8.7), water hardness (CaCO3 at 25–500 mg/L), dissolved organic carbon (DOC) concentration (1.6–18.4 mg/L), and DOC source on the chronic toxicity of copper to Daphnia magna were investigated by using a multifactorial, central composite test design. Natural dissolved organic matter (DOM) was collected at three sites in Belgium and The Netherlands by using reverse osmosis. For a total number of 35 toxicity tests performed, 21-d no-observed-effect concentrations (NOECs) of copper based on reproduction ranged from 29.4 to 228 μg/L and 21-d concentrations of copper causing 50% reduction of reproduction (EC50s) ranged from 41.5 to 316 μg/L. Statistical analysis revealed that DOC concentration and pH had a significant effect on copper toxicity but hardness (at the levels tested) did not. In general, an increase in pH or DOC resulted in a linear increase of 21-d NOEC and EC50 values. All DOMs (originating from three different sources) reduced copper toxicity to the same extent. Multiple linear regression analysis on the results of all 35 toxicity tests revealed that DOC concentration is the most important factor for chronic toxicity of copper to D. magna, explaining about 60% of the observed variability, whereas pH only explained about 15% of the observed variability. Regression models were developed (with DOC and pH as parameters) that were capable of predicting NOECs and EC50s within a factor of 1.9 from observed NOEC and EC50 values obtained with eight natural surface waters spiked with copper. Until future research further elucidates the mechanisms underpinning the observed bioavailability relations, these empirical regression models can become a first simple tool for regulatory applications.
Comparing the solid phase and saline extract Microtox® assays for two polycyclic aromatic hydrocarbon-contaminated soils
Authors: Acheson Carolyn M. , Zhou Qin , Shan Yonggui , Sayles Gregory D. , Kupferle Margaret J.
Published: November 2004

The performance of remedial teatments is typically evaluated by measuring the concentration of specific chemicals. By adding toxicity bioassays to treatment evaluations, a fuller understanding of treatment performance is obtained. The solid phase Microtox® assay is a useful tool in characterizing the toxicity of contaminated soils and sediments. This study compares the performance of the solid phase and saline extract Microtox assays in two experiments using two soils contaminated with polycyclic aromatic hydrocarbons (PAHs). The first experiment, conducted to refine the solid phase assay procedures, evaluated sample holding times, sample replication, and reference toxicant controls. The effective concentration reducing light emission by 50% (EC50) of four samples was measured with eight replicates of each sample. Samples were stored for as long as two weeks without showing substantial changes in toxicity. For future studies, three replicates of each sample are recommended because that degree of replication yielded a statistical power of more than 95% in most samples. Phenol was a reliable reference toxicant with a mean EC50 of 21.76 and a 95% confidence interval of 15.6 to 27.9 mg/L. In a second experiment, the solid phase Microtox assay was compared to saline extract Microtox assays with mixing times ranging from 5 min to 16 h. The solid phase assay was more sensitive yielding EC50s 7 to 50 times lower than the extract EC50s. In addition, the saline extract assays displayed results that varied for mixing times of less than 2 h. Based on these two experiments, the solid phase Microtox test has proved to be a useful assay for measuring the toxicity of PAH-contaminated soils.
Development and field validation of a biotic ligand model predicting chronic copper toxicity to Daphnia magna
Authors: De Schamphelaere Karel A.C. , Janssen Colin R.
Published: November 2004

In this study, we developed a toxicity model predicting the long-term effects of copper on the reproduction of the cladoceran Daphnia magna that is based on previously reported toxicity tests in 35 exposure media with different water chemistries. First, it was demonstrated that the acute copper biotic ligand model (BLM) for D. magna could not serve as a reliable basis for predicting chronic copper toxicity. Consequently, BLM constants for chronic exposures were derived by multiple regression analysis of 21-d median effective concentrations (EC50s; expressed as Cu2+ activity) versus physicochemistry from a large toxicity dataset and the results of an additional experiment in which the individual effect of sodium on copper toxicity was investigated. The effect of sodium on chronic toxicity (log KNaBL = 2.91) seemed to be similar to its effect on acute toxicity (log KNaBL = 3.19). However, in contrast to the acute BLM, no significant calcium, magnesium, or combined competition effect was observed, and an increase in proton competition and bioavailability of CuOH+ and CuCO3 complexes was noted. Some indirect evidence was also found for some limited toxicity of complexes of copper with two of three tested types of dissolved organic matter. Because the latter was only a minor effect, this factor was not included in the chronic Cu BLM. The newly developed model performed well in predicting 21-d EC50s and no-observed-effect concentrations in natural water samples: 79% of the toxicity threshold values were predicted within a factor of two of the observed values. It is clear, however, that more research is needed to provide information on the exact mechanisms that have resulted in different BLM constants for chronic exposures (as opposed to acute exposures). It is suggested that the developed model can contribute to the improvement of risk assessment procedures of copper by incorporating bioavailability of copper in these regulatory exercises.