bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toxicity of binary mixtures of organic chemicals
Authors: Chen Chung‐Yuan , Chiou Yuen‐Shian 
Published: October 2006

AbstractToxicity of binary mixtures of organic chemicals was evaluated using the Microtox test, in order to derive a more realistic approach for predicting mixture toxicity. Both additive and less than additive effects were found from binary mixtures of nonreactive toxicants. Concentration addition can be expected between two nonreactive chemicals, provided that the requirement of parallel dose—response curves is fulfilled. The study also identified the conditions for a complex—type joint action to take place. Finally, experimental isobolograms were analyzed based on a bivariate toxicity model to provide a rational estimation of model parameters. The isobolograms and the additive indices generated by this study can be used to predict the combined toxic effects from various organic mixtures. © by John Wiley & Sons, Inc.
Anthropogenic contaminants and fish health along an urban waterway
Authors: Ostrander Gary K. , Kuehn Ron L. , Berlin K. Darrell , Hawkins William E. 
Published: October 2006

AbstractField studies were conducted along an urban/industrial river to investigate the potential relationship between anthropogenic contaminants, including those related to oil refining, and fish health. The channel catfish, Ictalurus punctatus, served as the benthic sentinel species for these studies. At least 15 aromatic hydrocarbons known to be associated with oil refining and/or other industrial activities were detected at impacted stations including known carcinogens and mutagens [e.g., anthracene and benzo(a)pyrene]. At an appropriate reference station, no anthropogenic contaminants were identified in the waters and only 2 were observed in the sediments. Catfish collected from the reference station were significantly heavier, longer, and had higher relative weights. Morphological deformities such as clubbed, split, and missing barbels were observed on 37.8% of the fish collected from the impacted stations, while none were observed on fish from the reference station. Livers of catfish collected from the impacted stations exhibited a variety of histological changes consistent with contaminant exposure including vacuolated hepatocytes, pigment deposits, and other hepatoxic changes. These sublethal changes appear to be associated with chemical contamination and represent compromised health of individual organisms and, potentially, populations. © by John Wiley & Sons, Inc.
Evaluation of the genotoxicity of environmental contaminants in sediments to rainbow trout hepatocytes
Authors: Gagné F. , Blaise C. 
Published: October 2006

AbstractRainbow trout hepatocytes were used as an in vitro bioassay to assess the genotoxic potential of single chemicals and marine sediment extracts. Freshly prepared trout hepatocytes were exposed to either benzo[a]pyrene, N‐methyl‐N′‐nitro‐N‐nitrosoguanidine, β‐naphtoflavone, or organic extracts of marine sediments for 24 h at 15°C. Genotoxicity was assayed using the nick translation assay, which makes use of a nonradioactive nucleotide (biotin‐dUTP), and the DNA alkaline precipitation assay followed by fluorometric detection of DNA strands. Exposure to benzo[a]pyrene or methyl‐N′‐nitro‐N‐nitrosoguanidine, known indirect‐and direct‐acting genotoxins respectively, produced genotoxicity to rainbow trout hepatocytes with both assays. β‐Naphtoflavone displayed genotoxic activity in trout hepatocytes. Sediment extracts and reference sediment extracts displayed high toxicity and genotoxicity to trout hepatocytes. Chemical analyses showed that these sediments contained significant amounts of organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. Cell toxicity was correlated with total levels of organochlorine pesticides and polychlorinated biphenyls but not total levels of polycyclic aromatic hydrocarbons. No positive correlation was found with the nick translation assay between total levels of chemicals and genotoxicity in marine sediments. Genotoxicity obtained with the alkaline precipitation assay was correlated with levels of the organochlorine pesticide DDT. However, more tests would be required to further substantiate possible links with other specific chemicals. © by John Wiley & Sons, Inc.
Effect of nitrite exposure on hematological parameters and blood respiratory properties in the sea bass Lates calcarifer
Authors: Woo N. Y. S. , Chiu S. F. 
Published: October 2006

AbstractChanges in hematological parameters and blood respiratory properties of Lates calcarifer in response to nitrite exposure were studied. Exposure to 10 mg · L−1 NO2‐N for 8 days resulted in significant increases in blood nitrite and methemoglobin contents. Total hemoglobin was reduced resulting in an overall decline in functional hemoglobin. There was no significant change in hematocrit and red blood cell count.In another set of experiments, hematological parameters and venous blood oxygen tension of L. calcarifer after exposure to 15, 20, 30, 50, and 80 mg · L−1 NO2‐N for 4 days were determined. Blood nitrite and methemoglobin content increased proportionally to the increase in ambient nitrite concentration. The methemoglobin content (as percent of total hemoglobin) of fish immersed in a nitrite concentration equivalent to the 96 h LC50 (93 mg · L−1 NO2‐N) was estimated to be 83%. Venous blood oxygen tension tended to decrease as nitrite concentration increased.In a third set of experiments, sea bass were exposed to 50 mg · L−1 NO2‐N for 4 days. Exposure to nitrite resulted in lowered arterial and venous blood oxygen tensions, arterial and venous oxygen content, and blood oxygen capacity. However, no change in venous blood pH was observed between control and nitrite‐treated fish.The blood of Lates has a relatively low oxygen affinity (P50 = 14.5 ± 2.3 mm Hg) with a Hill coefficient (n) of 1.46. Exposure of fish to 50 mg · L−1 NO2‐N resulted in a leftward and upward shift of the blood oxygen dissociation curve (P50 = 5.9 ± 1.6 mm Hg; n = 0.99). The increased blood oxygen affinity in nitrite‐treated fish probably facilitated oxygen loading from water to the blood stream at the respiratory surfaces so as to compensate for the decline in oxygen carrying capacity. © by John Wiley & Sons, Inc.
Response of laboratory ecosystems to environmental stress: Effect of phenol
Authors: Pratt J. R. , Bowers N. J. , Niederlehner B. R. , Cairns J. 
Published: October 2006

AbstractEcologically realistic laboratory and field simulated ecosystems (microcosms and mesocosms) are playing increasing roles in fate and effect testing of chemicals and mixtures. Controlled ecosystems allow evaluation of toxicant effects on collective and emergent ecosystem properties. Information is needed to evaluate the validity of test system responses, interpretability of results, and cost effectiveness of simulated ecosystem tests. We developed replicate microcosms using periphyton on polyurethane artificial substrates. Source communities were obtained from two ecosystems—a reservoir in Kentucky and a softwater pond in Virginia—and tested for effects of continuous inputs of phenol (up to 30 mg/L) over 21 days. System responses measured included several biomass estimators, net oxygen production, and protozoan species richness. Communities were generally insensitive to phenol input. Primary production in microcosms from both ecosystems was inhibited at phenol concentrations >10 mg/L and chlorophyll a concentrations were also depressed. Other biomass estimators (protein, hexosamine) were not affected or were stimulated at lower (⩽10 mg/L) phenol concentrations. Protozoan species numbers were not affected. Functional shifts in the communities preceded adverse structural effects. Effect levels were similar for both communities, although the more complex community with greater biomass (Kentucky) showed more significant responses than the simpler community (Virginia). Systems showed resistance to phenol levels that were actually toxic in standard single‐species tests, suggesting that ecosystems may differ in magnitude and rate of response to some nonpersistent toxicants.
The effect of reservoir‐induced circulation on numbers of indicator bacteria in freshwater swim embayments
Authors: Johnstone Donald L. , Babb Alan F. , Bailey Gary C. 
Published: October 2006

AbstractThe objectives of the investigation were to determine specific hydraulic exchange rates that provide water in swim embayments that will meet fecal coliform standards for swimming, and to determine the water quality parameters that reflect rates of exchange of main channel waters with swim embayment waters. Bacteriology, water chemistry and hydraulic exchange rates were determined on three test swim embayments of good, acceptable, or unacceptable water quality. It was concluded that: (1) fecal coliform numbers may increase 50–100% above background even with high hydraulic exchange; (2) 93% of the embayment water must be exchanged every 24 h to meet coliform standards; (3) the ratio of fecal coliforms, turbidity, and temperature in swim waters to those same parameters in exchange waters is the most accurate way of assessing exchange; and (4) sediments act as a repository for enteric bacteria.
A study of contamination of suspended stream sediments with Escherichia coli
Authors: Palmateer G. A. , McLean D. E. , Walsh M. J. , Kutas W. L. , Janzen E. M. , Hocking D. E. 
Published: October 2006

AbstractSince stream bottom sediments indicate a history of the type and amount of pollution occurring in a watercourse, bacterial sediment analyses were conducted on samples from nine sites located along the length of the Desjardine Drain.The bottom sediments below farms on the drain, from the headwaters to the mouth, were found to be contaminated with Escherichia coli and fecal Streptococci at 106 organisms per 100 g.To determine if fecal wastes could reach the mouth of the drain at the Ausable River, a nalidixic acid resistant E. coli (NAR) was dispensed into the drain headwaters. The bacterium traveled the entire 17 km of the drain during a 5‐d period. As the level of E. coli (NAR) in the 100 L of inoculum simulated a single runoff event occurring at the first farm at the drain source, the potential of all downstream farms to affect stream water quality many kilometers from the point of entry of fecal waste is readily apparent.To further elucidate the mechanism of transport of E. coli, which become sorbed to stream bottom sediments, detailed particle analyses of the suspended sediments of the drain are being conducted. Using immunofluorescence microscopy, specific particle‐size fractions are being examined to determine the number of E. coli and fecal Streptococci sorbed to the suspended particulates.The fecal component of agricultural waste entering the Desjardine Drain was found to significantly contaminate sediments, causing impairment of the water quality. This is reflected in the reduction of usage of the stream for livestock watering and as well for human consumption and recreational activities.
Kinetics of decomposition of 2,4‐dichlorophenoxyacetic acid by Alcaligenes eutrophus JMP134 and in soil
Authors: Stenström John 
Published: October 2006

AbstractData on the decomposition of 2,4‐dichlorophenoxyacetic acid (2,4‐D) by pure cultures of Alcaligenes eutrophus JMP134 and in soil were obtained to investigate the validity of the Eq. (1), c = c0 ‐ k1t1/2 for decomposition at a decreasing rate by a constant amount of enzymes, and Eq. (2), c = c0 ‐ k1t1/2, for decomposition at an increasing rate by an exponentially increasing amount of cells. In the equations, c is the concentration of 2,4‐D at time t, c0 is the initial concentration of 2,4‐D, q is the maximum metabolic rate, N0 is the initial amount of 2,4‐D‐degrading microorganisms, and k1 and k2 are rate constants. Equation 2 satisfactorily described the data on decomposition of 2,4‐D by A. eutrophus at c0 of 100–400 μg mL−1, with N0 of 0.33‐11.8 × 107 cells mL−1, and at initial pH values between 7.1 and 8.4. At an initial pH of 6.1 there was accumulation of 2,4‐dichlorophenol (DCP), and the pattern of decomposition of 2,4‐D was sigmoidal. When approximately 20 μg of DCP mL−1 had accumulated, the kinetics of decomposition switched from Eq. (2) to Eq. (1). Growth and DCP accumulation then also became linear with t1/2. Equation (1) was also valid for decomposition of 2,4‐D under conditions of nitrogen starvation. In soil, Eq. (1) was valid when the number of 2,4‐D degrading microorganisms was constant, and Eq. (2) was valid when the number increased exponentially. It is concluded that several occurring patterns of decomposition are described mathematically by Eq. (1), by Eq. (2), or by the sum of these equations. Sigmoidal curves are described by combining the equations in a sequence, thus providing an alternative to models where decomposition curves are treated by one continuous function.
Relationships between microtox test results, extraction methods, and physical and chemical compositions of marine sediment samples
Authors: True Christie J. , Heyward Andrew A. 
Published: October 2006

AbstractSamples of marine subtidal sediments collected in 1985 and 1986 from Elliott Bay, Washington, were analyzed at the Environmental Laboratories of the Municipality of Metropolitan Seattle as part of a larger study. Interstitial water and solvent extracts of subtidal sediments were analyzed by the Microtox procedure to determine toxicity. Particle size distribution, and concentration of oil and grease, metals, and polynuclear aromatic hydrocarbons, were compared to toxicity of interstitial water and solvent extracts. Physical and chemical compositions of sediments affects the toxicities of solvent extracts and interstitial water extracts differently. Samples with smaller particle sizes had relatively high concentrations of oil and grease and metals, and less toxic interstitial water. Samples with larger particles had less oil and grease and metals, and more toxic interstitial water. The opposite was true for the solvent extracts: samples with smaller particle sizes with relatively higher concentrations of oil and grease and metals had more toxic solvent extracts. Samples containing larger particles with relatively lower concentrations of oil and grease and metals had less toxic solvent extracts. No correlations were found between the toxicity of the solvent extracts and polynuclear aromatic hydrocarbons. The Microtox procedure has the potential to estimate toxicity of both water‐soluble and solvent‐soluble compounds in marine sediments if two different extraction procedures are used.
Toxicity of mixtures of aquatic contaminants using the luminescent bacteria bioassay
Authors: Ribo J. M. , Rogers F. 
Published: October 2006

AbstractThe toxic effect of single organic contaminants to aquatic biota is relatively easy to assess using classic aquatic toxicity bioassays. Unfortunately, contaminants are present in the aquatic environment in mixtures of unknown composition. Moreover, antagonistic and synergistic interactions make the prediction of the real environmental hazard posed by organic contaminants more complicated. A mathematical algorithm has been developed to predict the toxicity of mixtures of organic contaminants to aquatic biota using toxicity data for the individual components of the mixture. The Microtox® toxicity bioassay was used to obtain the toxicity data for a set of chlorinated phenols that were used as test compounds to validate the model. The unique characteristics of the Microtox bioassay make it a perfect tool to confirm experimentally the ability of the model to estimate the combined toxic effect of mixtures of organic contaminants.
Decolorization and biodegradation of methyl red by acetobacter liquefaciens
Authors: So K. O. , Wong P. K. , Chan Kwong‐Yu 
Published: October 2006

AbstractDecolorization and biodegradation of the azo dye methyl red (2′‐carboxy‐4‐N,N‐dimethylamino‐azobenzene) in shaking and static cultures of the strict aerobe Acetobacter liquefaciens S‐1 were demonstrated by the disappearance of the brownish orange color of the methyl red containing medium (pH 7.5), by the decrease in absorption maximum of methyl red, and by the identification of two compounds 2‐aminobenzoic acid (anthranilic acid) and N,N′‐dimethyl‐p‐phenylene diamine (4‐N,N‐dimethylamino‐aniline) formed by reductive cleavage of methyl red in parallel with incubation time. Decolorization of methyl red was essentially completed within 17 h of incubation in both shaking and static cultures, which contained 1 g/L of (NH4)2SO4 as nitrogen source, 1% ethanol as carbon source, and up to 400 ppm of methyl red. Cells of A. liquefaciens S‐1 were able to metabolize methyl red as sole nitrogen source for growth, although the time required to achieve high decolorization efficiency (98%) of methyl red was considerably longer (72 h) under this condition.
A rapid and simple toxicity assay based on growth rate inhibition of Pseudomonas fluorescens
Authors: Paran J. H. , Sharma S. , Qureshi A. A. 
Published: October 2006

AbstractA simple and rapid test, based on growth rate inhibition (GRI) of Pseudomonas fluorescens, is described for toxicity screening and assessment. The test involves challenging standardized suspensions [0.2 optical density (OD) at 600 nm] of exponentially growing cells with various concentrations of a toxicant at 33°C and monitoring changes in the growth rate by OD measurements after 0.5, 1.0, 1.5, and 2.0 h. The toxicity end point is measured as the effective concentration of a test sample that causes 50% inhibition of growth rate (EC50) during each designated time period. Several metal salt solutions, organic compounds, and complex effluents were screened using this test and data compared with those obtained using the Microtox® assay. Results indicated that the P. fluorescens GRI test could be used as a valuable part of a battery of short‐term bioassays for toxicity screening and assessment.
A systematic study of the aerobic and anaerobic biodegradation of 18 chlorophenols and 3 cresols
Authors: Liu D. , Pacepavicius G. 
Published: October 2006

AbstractAerobic and anaerobic biodegradation processes for 18 chlorophenols and 3 cresols were systematically evaluated under a controlled laboratory system, using an acclimatized mixed culture of pentachlorophenol‐degrading bacteria. The biodegradation processes were characterized based on the lag time (time in hours required to observe 10% degradation of the added test chemical against the control), t90 (time in hours required to degrade 90% of the added test chemical). The results indicate that nonspecific generalizations such as the degree of a chemical's chlorination cannot be reliably used to predict the persistence of chemicals in the environment. On the other hand, a systematic analysis of the molecular structure of analogues and related chemicals, in particular the positions of chlorine substitution on the phenolic ring, appears to be the logical approach to provide useful information for predicting the environmental fate of existing and new chemicals. The substitution effect in dictating a chlorophenol's biodegradability appears to follow in the descending order of 2,4 > 4 > 3,5 > 2,6 > 3, or 5, or 2. Microbial acclimation was found to be a distinct feature associated with the biodegradation of toxic substances and thus having the potential to be utilized in characterizing the biodegradation process of such chemicals. Ignorance of this acclimation period in kinetics study could nullify the usefulness of using mathematical models in predicting the environmental fate of chemical compounds.
Simple two‐step sediment extraction procedure for use in genotoxicity and toxicity bioassays
Authors: Kwan K. K. , Dutka B. J. 
Published: October 2006

AbstractThree simple sediment extraction procedures, using Milli‐Q water, DMSO, and methanol, were applied to 16 sediment samples collected from the Thames River, Ontario, Canada. The three extracts were tested for the presence of toxicity and genotoxicity using the Microtox,® Toxi‐Chromotest,® and Mutatox® (with and without S9) procedures. Results of the study indicated that the Mutatox genotoxicity screening test was an extremely sensitive procedure responding to chemicals in all three types of extracts. Methanol was found to be more efficient than DMSO in extracting toxic and genotoxic chemicals from these sediments. Procedural details and results are discussed.
Defining the nutritional status and dietary intake of older heart failure patients
Authors: Price Rosemary J.G. , Witham Miles D. , Mcmurdo Marion E.T. 
Published: October 2006

Background Little information exists about diet in the management of heart failure. Aims To describe the nutritional and biochemical status, and the dietary intake of older heart failure patients. Methods Stable outpatients and patients with recent hospitalisation for decompensated heart failure were recruited. Anthropometric measurements, handgrip strength, biochemical values and echocardiography were recorded. Patients kept 7-day food diaries and completed questionnaires concerning food provision. Results Forty-five patients with a mean (S.D.) age of 80.8 (6.8) years were studied and classed according to the New York Heart Association (NYHA) (11% Class I, 27% Class II and 62% Class III). Mean (S.D.) body mass index (BMI) was 27.1 (5.4) kg/m2 with 7% of patients having a BMI<20 kg/m2 and 56% with a BMI above 25 kg/m2. 64% of participants failed to achieve the estimated average requirements for energy intake; 82% took more than 2 mg of sodium daily; and 18% had a potassium intake above 3500 mg/day. Only 29% of individuals did not need assistance with food shopping, whilst 58% required assistance with meal preparation. Conclusion Possible targets for dietary intervention in older heart failure patients have been identified but whether such changes would be beneficial to patients is unknown.
Clinical trials update from the Heart Failure Society of America meeting: FIX‐CHF‐4, selective cardiac myosin activator and OPT‐CHF
Authors: Cleland John G.F. , Coletta Alison P. , Clark Andrew L. 
Published: October 2006

AbstractThis article provides information and a commentary on trials relevant to the pathophysiology, prevention and treatment of heart failure, presented at the Heart Failure Society of America meeting held in Seattle in September 2006. All reports should be considered as preliminary data, as analyses may change in the final publication.Devices designed to improve cardiac contractility may have improved exercise tolerance and quality of life in the FIX‐CHF‐4 study; however, uncertainties in trial interpretation exist. The results of a study reporting the first administration of the selective myosin activator CK‐1827452 to human volunteers, support the initiation of clinical trials in heart failure patients. In OPT‐CHF, oxypurinol failed to show benefit compared to placebo for the treatment of heart failure, although a retrospective subgroup analysis suggests that it may be beneficial in patients with elevated serum uric acid levels.