bluuebunny/crossref_metadata_2025 huggingface dataset:
Resonant tunneling probabilities for an N‐terminal junction by the flux averaging method
Authors: Berman Lihu , Peskin Uri
Published: July 2004

The flux averaging method for time‐dependent calculations of resonant tunneling probabilities is generalized for the case of multichannel scattering by analyzing a generic model for resonant tunneling in a molecular junction with N terminals (N open scattering channels). The transmission probability between any two channels is expressed as a weighted average of time integrals over probability fluxes through different spatial contours. In the case of resonance scattering the transmission probability is shown to converge within a (short) direct‐scattering timescale, circumventing the problem of slow convergence of each one of the time integrals due to population of a long‐lived resonance state. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Simulation of liquid water using a high‐rank quantum topological electrostatic potential
Authors: Liem S. Y. , Popelier P. L. A. , Leslie M.
Published: July 2004

For the first time a potential based on high‐rank atomic multipole moments computed according to quantum chemical topology (QCT) has been used in molecular dynamics simulations. Completing earlier work on the performance of this QCT potential on small gas‐phase van der Waals complexes we now focus on the liquid structure of water. Other than the parameterL, which keeps track of the rank of the electrostatic interaction, the current QCT potential contains only two adjustable parameters of the Lennard–Jones type. A system of 216 water molecules was simulated including long‐range interactions represented by a high‐rank multipolar Ewald summation. High‐order multipolar interactions (L= 5) are essential to recover the typical features of a liquid‐like structure. Liquid simulations at five different temperatures showed a maximum in the density and a temperature profile that agrees fairly well with experiment. The density of simulated water at 300 K and 1 atm is about 0.1% off the experimental value, while the calculated potential energy of the liquid is within 3% of the experimental result. The experimental value of the self‐diffusion coefficient is underestimated by 35%. The value ofCpis overestimated by 40% and the thermal expansion coefficient α by 37%. The calculated correlation coefficients between the calculated QCT profile and the experimental profile ofgOO(r),gOH(r), andgHH(r) are 0.976, 0.970, and 0.972, respectively. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
The Dirac equation in the algebraic approximation. IX. Matrix Dirac–Hartree–Fock calculations for the HeH and BeH ground states using distributed Gaussian basis sets
Authors: Quiney H. M. , Glushkov V. N. , Wilson S.
Published: July 2004

Using large component basis sets of distributed s‐type Gaussian functions with positions and exponents optimized so as to support Hartree–Fock total energies with an accuracy approaching the sub‐μhartree level, Dirac–Hartree–Fock–Coulomb calculations are reported for the ground states of the open‐shell molecular systems HeH and BeH. The small component basis sets are obtained by applying the (strict) kinetic balance condition. Explicit expressions are given for the electron repulsion integrals required for relativistic atomic and molecular electronic structure calculation, using basis sets of distributed G‐spinors. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Hohenberg–Kohn theory including spin magnetism and magnetic fields
Authors: Kohn Walter , Savin Andreas , Ullrich Carsten A.
Published: July 2004

Beginning with work by U. von Barth and L. Hedin in 1972 and continuing with recent papers in 2001 by K. Capelle and G. Vignale and by H. Eschrig and W. E. Pickett, questions have been raised about the meaning and validity of Hohenberg–Kohn theory when spin magnetism and/or magnetic fields are present. This article offers clarifications of some of these questions. In particular, it also concludes that these questions do not affect spin‐density functional theory for nondegenerate ground states as currently practiced. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Erratum: Nature of O2, CO, and CN binding to hemoprotein models
Authors: Torrens F.
Published: July 2004

The original article to which this Erratum refers was published in International Journal of Quantum Chemistry (2004) 99(6)
Development and evaluation of symbolic model checker based on approximation for real‐time systems
Authors: Yamane Satoshi , Nakamura Kazuhiro
Published: July 2004

In this paper, the authors describe symbolic model checking for real‐time systems based on approximation. It is important to determine how to reduce the increase in verification cost due to timed‐state processing during symbolic model checking of a real‐time system. Verification techniques that use a set of approximate states instead of exact timed states in a reachability analysis of a real‐time system have been proposed to increase the effect in reducing the verification cost. Therefore, the authors propose a symbolic model checking technique for real‐time systems that uses a set of approximate states. The verification algorithm calculates the set of approximate states by performing fixpoint calculations based on an approximation corresponding to a computation tree logic (CTL) formula. The authors implemented the proposed algorithm and compared it with existing real‐time symbolic model checkers. They obtained results showing that the proposed technique is effective for verifying a large‐scale system that includes many clock variables. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(10): 83–101, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10565
Robust object detection using a Radial Reach Filter (RRF)
Authors: Satoh Yutaka , Kaneko Shun'ichi , Niwa Yoshinori , Yamamoto Kazuhiko
Published: July 2004

In this paper the authors report on a new algorithm used to separate an object from its background using a background image. In the past, simple background subtraction has been used because of its low processing costs and ease of implementation. However, because this method depends solely on brightness patterns in the object and shadows, it has problems such as an inability to deal with poor lighting conditions and an inability to detect regions in which the brightness levels of the object and shadows are similar. In order to resolve these problems, in this paper the authors propose a new filter process called a Radial Reach Filter (RRF). The authors define a new statistic called a Radial Reach Correlation (RRC) used to determine on a pixel‐by‐pixel basis the similar and dissimilar areas between a background image and a current scene. They then evaluate the local texture at pixel‐level resolution while reducing the effects of variations in lighting. In addition, by introducing a mechanism to adjust the defined region adaptively based on local characteristics of the background image, the authors are able to work with various shadows and objects in the scene. The authors perform a theoretical evaluation and experiments using real images to demonstrate the validity of their proposed method. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(10): 63–73, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10590
An efficient genetic algorithm for a fixed frequency assignment problem with limited bandwidth constraint
Authors: Matsui Shouichi , Watanabe Isamu , Tokoro Ken‐ichi
Published: July 2004

In this paper, we propose an efficient genetic algorithm (GA) for a fixed frequency assignment problem with limited bandwidth constraint. We propose a new GA‐based algorithm for the problem of minimizing the weighted sum of damage due to interference and damage due to blocked call, which was formulated by Jin and colleagues. The proposed algorithm, which uses a steady‐state GA that adaptively controls the mutation rate to search for an appropriate instruction sequence for a virtual machine performing the frequency assignment work, introduces a solution improvement algorithm based on a local search. The results of applying the proposed algorithm to benchmark problems, which show better performance than the existing GAs, indicate that this is an efficient algorithm. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(10): 32–39, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10677
A group formation support system based on substitute goods in group buying
Authors: Matsuo Tokuro , Ito Takayuki
Published: July 2004

In electronic marketplaces, group buying is seen as an effective form of electronic commerce and a promising field for applying agent technologies. We study decision support systems for buyers in group buying. In group buying, when buyers cooperate with each other, a seller can discount the price of a good. In many existing group buying sites, some sellers deal in the same sort goods or their imitations. Buyers form coalitions for each item on sale. Buyers cannot always purchase goods at a lower price, because the buyers' subgroups are distributed. Buyers need to search hard to find goods they can purchase. In this paper, we propose a group buying marketplace on the Internet. In our marketplace, buyers can purchase goods at a lower price by forming coalitions. Our system can provide a service in which buyers are integrated based on their multiattribute preferences (utilities). Our system supports buyers' decision making by using the Analytic Hierarchy Process. We propose three methods for group integration. First, buyers trade in simple group buying. Second, all buyers are integrated. Third, some buyers are integrated. The advantages of our market are that buyers' multiattribute utilities are effectively expressed in group integration and buyers can purchase goods at a lower price. Buyers' payments are decided based on their degree of compromise. A successful seller can sell goods in their stock. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(10): 23–31, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10695
A model of overt visual attention based on scale‐space theory
Authors: Satoh Shunji , Miyake Shogo
Published: July 2004

This paper proposes a vision model for object detection based on scale‐space theory, considering knowledge obtained in neurophysiology and human visual characteristics obtained in visual psychology. The proposed model is principally composed of (a) the early vision model and (b) the attention calculation model. In this paper, it is shown first that the visual characteristics can be described by a discretized scale space, considering their multichannel property, spatial nonuniformity, and orientation selectivity. The early vision model is formulated. Next, the attention calculation model and the operation algorithm are formulated on the basis of the knowledge obtained by scale‐space theory. The numerical experiments reveal that the proposed model has the following properties. (i) For objects with a high intensity difference, the center of overt attention moves to the center of the object. (ii) The spatial extent of overt/covert attention can be calculated adequately. (iii) The object is captured at the central region of the retina, where the resolution is the highest. Since the proposed model is based on scale‐space theory, the theory or model can be easily extended. There are other advantages from an engineering standpoint, such as simple structure, easy implementation, small computational requirements, and very few parameters to be adjusted. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(10): 1–13, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10708
Hazard assessment of a simulated oil spill on intertidal areas of the St. Lawrence River with SPMD‐TOX
Authors: Johnson B. Thomas , Petty James D. , Huckins James N. , Lee Ken , Gauthier Joanne
Published: July 2004

Phytoremediation in a simulated crude oil spill was studied with a “minimalistic” approach. The SPMD‐TOX paradigm—a miniature passive sorptive device to collect and concentrate chemicals and microscale tests to detect toxicity—was used to monitor over time the bioavailability and potential toxicity of an oil spill. A simulated crude oil spill was initiated on an intertidal freshwater grass‐wetland along the St. Lawrence River southwest of Quebec City, Quebec, Canada. Several phytoremediation treatments were investigated; to dissipate and ameliorate the spill, treatments included nutrient amendments with inorganic nitrogen sources (ammonium nitrate and sodium nitrate) and phosphate (super triple phosphate) with and without cut plants, with natural attenuation (no phytoremedial treatment) as a control. Sequestered oil residues were bioavailable in all oil‐treated plots in Weeks 1 and 2. Interestingly, the samples were colored and fluoresced under ultraviolet light. In addition, microscale tests showed that sequestered residues were acutely toxic and genotoxic, as well as that they induced hepatic P450enzymes. Analysis of these data suggested that polycyclic aromatic hydrocarbons were among the bioavailable residues sequestered. In addition, these findings suggested that the toxic bioavailable fractions of the oil spill and degradation products dissipated rapidly over time because after the second week the water column contained no oil or detectable degradation products in this riverine intertidal wetland. SPMD‐TOX revealed no evidence of bioavailable oil products in Weeks 4, 6, 8, and 12. All phytoremediation efforts appeared to be ineffective in changing either the dissipation rate or the ability to ameliorate the oil toxicity. SPMD‐TOX analysis of the water columns from these riverine experimental plots profiled the occurrence, dissipation, and influence of phytoremediation on the bioavailability and toxicity of oil products (parent or degradation products). © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 329–335, 2004.
Elemental sulfur: Toxicityin vivoandin vitroto bacterial luciferase,in vitroyeast alcohol dehydrogenase, and bovine liver catalase
Authors: Četkauskaitė Anolda , Pessala Piia , Södergren Anders
Published: July 2004

The aim of this research was to analyze the effects and the modes of action of elemental sulfur (S0) in bioluminescence and respiration ofVibrio fischericells and the enzymes crude luciferase, pure catalase, and alcohol dehydrogenase (ADH). Metallic copper removed sulfur and reduced the toxicity of acetone extracts of sediment samples analyzed in the bioluminescence test. The sulfur inhibition of cell bioluminescence was noncompetitive with decanal, the luciferase substrate; reversible, with maximum toxicity after 15 min (EC50= 11.8 μg/L); and almost totally recovered after 2 h.In vitropreincubation of crude luciferase extract with sulfur (0.28 ppm) weakly inhibited bioluminescence at 5 min, but at 30 min the inhibition reached 60%. Increasing the concentration of sulfur in the parts per million concentration rangein vitrodecreased bioluminescence, which was not constant, but depended on exposure time, and no dead‐end/total inhibition was observed. The redox state of enzymes in thein vitrosystem significantly affected inhibition. Hydrogen peroxide restored fully and the reducing agent dithiothreitol, itself toxic, restored only partially luciferase activity in the presence of sulfur. Sulfur (5.5 ppm) slightly inhibited ADH and catalase, and dithiothreitol enhanced sulfur inhibition. High sulfur concentrations (2.2 ppm) inhibited the bioluminescence and enhanced the respiration rate ofV. fischericells. Elemental sulfur data were interpreted to show that sulfur acted on at least a fewV. fischericell sites: reversibly modifying luciferase at sites sensitive to/protected by oxidative and reducing agents and by affecting electron transport processes, resulting in enhanced oxygen consumption. Sulfur together with an enzyme reducing agent inhibited the oxidoreductive enzymes ADH and catalase, which have SH groups, metal ion cofactors, or heme, respectively, in their active centers. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 372–386, 2004.
Toxicity assessment of oil‐contaminated freshwater sediments
Authors: Blaise Christian , Gagné François , Chèvre Nathalie , Harwood Manon , Lee Ken , Lappalainen Juha , Chial Belgis , Persoone Guido , Doe Ken
Published: July 2004

The performance of four microscale toxicity bioassays conducted on whole sediments was evaluated during a bioremediation project undertaken in 1999–2000 on a crude oil–contaminated freshwater shoreline of the St. Lawrence River, Quebec, Canada. The toxicity tests assessed included: (1) the Microtox® solid‐phase assay (MSPT), (2) the Biotox™ Flash solid‐phase test (Flash), (3) the algal solid‐phase assay (ASPA), and 4) the Ostracodtoxkit solid‐phase assay. Data generated with these assays were compared with those obtained using the standard endobenthic amphipod (Hyalella azteca) bioassay. Bioanalytical comparisons indicated that all five solid‐phase tests were useful in detecting the toxicity of oiled sediments; however, statistical analyses distinguished a difference in response between the invertebrate (amphipod and Ostracodtoxkit) and bacterial luminescence tests (MSPT and Flash). Based on these results, it is recommended that careful selection of biotests be made in the design of the test battery for assessment of residual oil sediment toxicity. Time‐series toxicity data generated with ASPA indicated that oiled sediments in the freshwater wetlands of the St. Lawrence River remained toxic to phytoplankton for at least 65 weeks and that remediation treatment was able to accelerate detoxification by 16 weeks. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 267–273, 2004.
Development of a biosensor for the detection of tributyltin
Authors: Horry Habib , Durand Marie‐José , Picart Pascal , Bendriaa Loubna , Daniel Philippe , Thouand Gérald
Published: July 2004

A biosensor (LUMISENS I), based on the inducible bioluminescence of the Escherichia coli strain TBT3 (Ec::luxAB TBT3), was developed for the detection of the biocide tributyltin. LUMISENS I was set up with a minibioreactor and additional equipment for growth monitoring and light acquisition. The 100‐mL minibioreactor has allowed us to establish a stable and reproducible environment for the bacteria (regulation of the growth rate, temperature, pH, and oxygenation), as well as for in situ contact with the xenobiotic. The optical components of the transducer were chosen according to the spectral emission of the strain being studied using a highly sensitive spectrophotometer that was initially devoted to Raman scattering. LUMISENS I was patented according to the in situ, automatic, and simultaneous measurement of the cell density and bioluminescence in the bioreactor. The first results showed that cells cultivated in a synthetic glucose medium provided a better detection limit than did those cultivated in a complex Luria–Bertani (LB) medium (0.02 and 1.5 μM of tributyltin, respectively). Cells maintained at a high growth rate (0.9 h−1) led to maximum bioluminescence. Moreover, air bubbling was efficient enough to provide suitable quantities of oxygen for both growth and light emission. When the TBT3 strain used the luxAB genes on its own, decanal, a long‐chain aldehyde, had to be added to obtain the bioluminescence reaction. We found that the continuous addition of decanal was the most effective means of obtaining this reaction. The monitoring of the bioluminescence after tributyltin induction showed that the aldehyde was not toxic up to 300 μM during a 7‐day experiment. Measurement of tributyltin with LUMISENS I was performed, which showed significant response up to 0.125 μM without any effect on optical density. Even though optimization of the performance of LUMISENS I is still under development, because of its original design, this biosensor is already in use as a warning system for the online monitoring of tributyltin. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 342–345, 2004.
Analysis of micronuclei in blue mussels and fish from the Baltic and North Seas
Authors: Baršienė Janina , Lazutka Juozas , Šyvokienė Janina , Dedonytė Veronika , Rybakovas Aleksandras , Bagdonas Edvardas , Bjornstad Anne , Andersen Odd Ketil
Published: July 2004

Micronuclei (MN) were analyzed in erythrocytes of flounder (Platichthys flesus) and wrasse (Symphodus melops) and in gill cells of blue mussels (Mytilus edulis). The organisms were collected from three study stations in the Baltic Sea and from seven stations in the North Sea (Karmsund area, Norway) 4 times. The statistically significant differences obtained were related to the season, sex of the fish, and sampling locality. Higher MN frequencies were found in fish and mussels collected from the most polluted study stations in the North Sea. The same tendency could be described in the Baltic Sea; however, it was masked by the recent oil spill from the Butinge oil terminal. Our results showing higher MN frequencies in presumably what were the most polluted study locations suggest that MN tests in fish and mussels may be used for the detection of genotoxic effects in a marine environment. The endpoint is well characterized and can be easily recognized, and the technique is convenient to use in field samplings following standard procedures and protocols. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 365–371, 2004.
Application of Toxkit microbiotests for toxicity assessment in soil and compost
Authors: Dubova L. , Zariņa Dz.
Published: July 2004

The potential of Toxkit microbiotests to detect and analyze pollution in agricultural soil and the quality of compost was studied. The toxicity tests used included seed germination biotests using cress salad (Lepidum sativum L.), tomato (Lycopersicum esculentum L.), and cucumber (Cucumis sativus L.), and the Toxkit microbiotests included those with microalgae (Selenastrum capricornutum), protozoa (Tetrahymena thermophila), crustaceans (Daphnia magna, Thamnocephalus platyurus, and Heterocypris incongruens), and rotifers (Brachionus calyciflorus). Experiments on compost were undertaken in a modified solid‐state fermentation system (SSF) and under field conditions (in a windrow). To promote the composting process, two strains of Trichoderma (Trichoderma lignorum and Trichoderma viride), as well as a nitrification association that regulated the nitrogen‐ammonification and nitrification processes were applied. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 274–279, 2004.
Effect of deicing salts on urban soils and health status of roadside trees in the Opole region
Authors: Czerniawska‐Kusza Izabela , Kusza Grzegorz , Dużyński Mariusz
Published: July 2004

This article reports on a study whose aim was to evaluate the impact of snow removal salts on urban soil properties and the health of roadside trees. The evaluation was done by chemical analyses of soil samples and plant matter combined with toxicity testing, performed with a Protoxkit F™, a protozoan microbiotest. Samples were collected at 45 locations on three main roads in the town of Opole (Poland). The roads differed in the snow removal technology and amount of chemical substances (mostly NaCl) used on them during the winter. The study showed that when soil was exposed to a high level of NaCl, it tended to be more alkaline and also exhibited increased content of Na+ and Cl−. The toxic effects of the soil extract on protozoa appeared at 26.0 mg Na+/100 g soil dry mass (s.d.m.) and 12.0 mg Cl−/100 g s.d.m., whereas salt injury symptoms (chlorosis and necrosis of the edge of leaf blades) appeared at 13.2 mg Na+/100 g s.d.m. and 3.9 mg Cl−/100 g s.d.m., becoming more severe at 26.0 mg Na+/100 g s.d.m. and 12.0 mg Cl−/100 g s.d.m. because of extensive necrosis and defoliation. The lysimetric experiment, which was used to test soil samples collected from the city park area, indicated that salt plays a significant role in the pollution of soil in urban areas, with the least toxic salt being CaCl2. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 296–301, 2004.
The medicinal leech as a convenient tool for water toxicity assessment
Authors: Petrauskienė Laima
Published: July 2004

Medicinal leeches previously were used in various toxicological and pharmacological studies because they are sensitive and easy to keep under laboratory conditions. Toxicological studies using leeches became restricted when their natural sources decreased dramatically. We breed medicinal leeches under laboratory conditions and have the possibility of using them for various investigations. The aim of the current study was to investigate changes in behavioral and physiological responses of leeches exposed to a heavy metal model mixture (HMMM). The composition of the HMMM was determined on the basis of the average annual amounts of representative metals (Zn, Mn, Cu, Cr, Ni, Cd, and Pb) in wastewater discharging from the Ignalina Nuclear Power Plant. An annual average was considered a concentration of 1%. Animals were exposed to 0.13%, 0.25%, 0.5%, 1%, and 2% concentrations of the HMMM. The avoidance responses, changes in body weight, feeding behavior, and excretion rates of the leeches were recorded. Avoidance response was observed in animals treated with 1% and 2% concentrations of the HMMM during the first 2 h of exposure. A decrease in body weight was recorded after a 4‐week exposure to all tested concentrations. Disturbances in feeding behavior were observed after a 4‐week exposure to 0.13%–2% concentrations. An increase in the defecation rate was observed during the 5‐week exposure to 0.25%–2% concentrations. The excretion rate via nephridia was decreased during postfeeding period after exposure to 0.25%–2% concentrations. The avoidance response of medicinal leeches can be used as an express method for water quality assessment, whereas physiological responses may be used for the assessment of chronic toxicity of polluted environments. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 336–341, 2004.
Toxicity to Tradescantia of technogenic radionuclides and their mixture with heavy metals
Authors: Marčiulionienė Danutė , Montvydienė Danguolė , Kiponas Dalius , Lukšienė Benedikta , Butkus Donatas
Published: July 2004

The genotoxic effects on Tradescantia of 137Cs, 90Sr, and 236, 242Pu, a heavy metal mixture [Cd, Cr(VI), Cu, Mn(II), Ni, Pb, Zn] and of a complex mixture of these toxicants were determined. The impact of radionuclides on plants subjected to ionizing radiation exposure was estimated. The number of somatic mutations and the quantity of nonviable stamen hairs were used as end points in the testing. An increase in the quantity of nonviable stamen hairs was observed with increasing internal exposure to 137Cs, 90Sr, and 236, 242Pu; however, the number of somatic mutations was not observed to be dependent on ionizing radiation. The internal dose of individual radionuclides necessary to decrease the quantity of viable stamen hairs in Tradescantia by 50% can be arranged in the following sequence: 236, 242Pu > 137Cs > 90Sr. Tradescantia died in the mixture of the radionuclides 90Sr, 137Cs, and 236Pu (5 × 10−2, 7 × 10−5, and 4 × 10−10 Gy, respectively) after 14 days, whereas the heavy metal mixture caused somatic mutations in 3% of the Tradescantia and nonviable stamen hairs in 7% but no mortality. However, the Tradescantia died in a combined mixture of these heavy metals and the radionuclides after 14 days. On the basis of all these observations, it can be concluded that the toxic effect of radionuclides was more significant than that of heavy metals. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 346–350, 2004.
Assessment of toxic interactions of heavy metals in a multicomponent mixture using Lepidium sativum and Spirodela polyrrhiza
Authors: Montvydienė Danguolė , Marčiulionienė Danutė
Published: July 2004

The toxicities of copper, chromium, cadmium, nickel, manganese, zinc, and lead ions and various concentrations of mixtures of them were studied using the aquatic plant Spirodela polyrrhiza and the terrestrial plant Lepidium sativum. The composition of the model mixture was based on average analytical data of the annual amounts of representative heavy metals (HM) in wastewater discharged from the Ignalina Nuclear Power Plant (Lithuania) during 1996. The observed and predicted effects of the HM mixture on tested plants were evaluated and compared with the prediction models used in describing the toxic interactions of heavy metals in the mixture. The type of toxic interaction at each tested concentration of the mixture was assessed by a statistical approach that tested the null hypothesis of additive toxicity (Ince et al., 1999) and the mixture toxicity index (MTI; Könemann, 1981). For both plant organisms the effect of the HM mixture calculated using the MTI was synergistic. However, assessment of the HM interaction type at 50% effect concentrations using the hypothesis of additive toxicity showed a synergistic effect for Spirodela polyrrhiza and an additive effect for Lepidium sativum. Though the results obtained using both prediction models for assessing the HM mixture's toxicity were similar, in our opinion, the additive toxicity model is more suitable than the MTI model because the former allows evaluation of the impact of various mixture concentrations, not only those with a 50% effect. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 351–358, 2004.
Field study on changes in viability of airborne fungal propagules exposed to UV radiation
Authors: Ulevičius V. , Pečiulytė D. , Lugauskas A. , Andriejauskienė J.
Published: July 2004

The responses of airborne fungi to UV‐B under natural conditions were investigated at the coastal station in Preila, Lithuania. Results of this investigation demonstrated that solar radiation has a marked lethal effect on outdoor airborne fungi. Sensitivity to solar radiation was the highest for the fungal propagules collected late in the evening (relative recovery 6.2%) and early morning (25.3%). The lowest sensitivity to solar radiation was observed for fungal propagules collected at midday (50.0%) and in the afternoon (53.0%). The reason for the lethal effect is thought to be elimination of the sensitive fraction of the night‐time fungal populations as solar radiation gradually increases beginning at dawn. Among 356 fungus strains isolated during the investigations, 128 can be characterized as potential pathogens, and 21 strains among those most common in fungal populations belonging to plant, animal, and human pathogen groups. The collected fungal populations were exposed to solar UV‐B irradiation for 2 h (from 12 p.m. to 2 p.m.). Fungal communities in the air samples were composed of saprotrophs, some of which are regarded as potential phytopathogens (Alternaria, Cladosporium, and Fusarium) or as entomopathogens (Beauveria, Paecilomyces, and Metarhizium). The airborne fungal species identified after exposure to solar radiation were predominantly: Aspergillus niger, Alternaria alternata, Cladosporium cladosporioides, Arthrinium phaerosporum, and dematiaceous sterile mycelium. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 437–441, 2004.
Genotoxicity related to transfer of oil spill pollutants from mussels to mammals via food
Authors: Lemiere Sébastien , Cossu‐Leguille Carole , Bispo Antonio , Jourdain Marie‐José , Lanhers Marie‐Claire , Burnel Daniel , Vasseur Paule
Published: July 2004

Heavy fuel oils containing high levels of polycyclic aromatic hydrocarbons (PAHs) were released into the marine environment after the Erika oil spill on the Atlantic coast. As highly condensed PAH pollutants can bioaccumulate in invertebrates, their transfer to vertebrates through the food chain was of concern. This study aimed to estimate potential genotoxic effects in rats fed for 2 or 4 weeks with the marine mussel Mytilus edulis contaminated by oil pollutants. Two levels of PAH contamination were studied, around 100 and 500 μg of total PAHs/kg dry weight (d.w.) in mussels. Genotoxic damage in rats was investigated by single‐cell gel electrophoresis (Comet assay) and micronucleus assays in liver, bone marrow, and peripheral blood. DNA damage was observed in the liver of rats fed with the most contaminated mussels (500 μg PAHs/kg d.w.).DNA damage also was observed in the bone marrow but less than that in the liver. A small increase in micronuclei frequency was registered as well. This work underlines the bioavailability of pollutants in fuel‐oil‐contaminated mussels to consumers and the usefulness of the Comet assay as a sensitive tool in biomonitoring to analyze responses to PAH transfer in food. The occurrence of substituted PAHs and related compounds such as benzothiophenes in addition to nonsubstituted PAHs in fuel oils and mussels raised the question of whether they were implicated in the genotoxic effects registered in rats. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 387–395, 2004.
Toxicity testing of heavy‐metal‐polluted soils with algae Selenastrum capricornutum: A soil suspension assay
Authors: Aruoja Villem , Kurvet Imbi , Dubourguier Henri‐Charles , Kahru Anne
Published: July 2004

A small‐scale Selenastrum capricornutum (Rhapidocelis subcapitata) growth inhibition assay was applied to the toxicity testing of suspensions of heavy‐metal‐polluted soils. The OECD 201 standard test procedure was followed, and algal biomass was measured by the fluorescence of extracted chlorophyll. The soils, which contained up to (per kilogram) 1390 mg of Zn, 20 mg of Cd, and 1050 mg of Pb were sampled around lead and zinc smelters in northern France. The water extractability of the metals in suspensions (1 part soil/99 parts water w/v) was not proportional to the pollution level, as extractability was lower for soil samples that were more polluted. Thus, the same amount of metals could be leached out of soils of different levels of pollution, showing that total concentrations of heavy metals in soil (currently used for risk assessment purposes) are poor predictors of the real environmental risk via the soil–water path. Despite high concentrations of water‐extracted zinc (0.6–1.4 mg/L of Zn in the test), exceeding by approximately 10‐fold the EC50 value for S. capricornutum (0.1 mg Zn/L), 72‐h algal growth in the soil extracts was comparable or better than growth in the standard control OECD mineral medium. The soil suspension stimulated the growth of algae up to eightfold greater than growth using the OECD control medium. Growth stimulation of algae was observed even when soil suspensions contained up to 12.5 mg Zn/L and could not be explained by supplementary nitrogen, phosphorous, and carbonate leached from the soil. However, if the growth of algae in suspensions of clean and polluted soils was compared, a dose‐dependent inhibitory effect of metals on algal growth was demonstrated. Thus, as soil contains nutrients/supplements that mask the adverse effect of heavy metals, a clean soil that has properties similar to the polluted soils should be used instead of mineral salt solution as a control for analysis of the ecotoxicity of soils. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 396–402, 2004.
Evaluation of solar UV damage to Crepis capillaris by chromosome aberration test
Authors: Rančelienė V. , Šlekytė K. , Cieminis K.
Published: July 2004

Ultraviolet (UV) radiation comprises only a small portion of the electromagnetic spectrum of solar light, but it exerts a disproportionally greater genotoxic effect on all organisms, including water plants. However, genotoxicity evaluation of solar UV is complicated because of the simultaneous actions of UVB, UVA, and photoreactivating light (PHL). The latter very effectively repairs the main type of DNA lesions, pyrimidine dimers (PD), which are induced specifically only by UV. However, other types of DNA lesions are induced by UV; they are unrepairable by PHL and present a real danger to the plant genome. To evaluate this part of DNA lesions, the frequency of chromosome aberrations (CA) was determined after solar UVB and UVB+UVA irradiation with or without PHL. Meristematic cells of Crepis capillaris were irradiated in special chambers with filters. The 4‐year investigation showed that only about half of CA had been repaired with PHL. Both findings of the study, of the part of CA that remained after PHL and of the stronger genotoxicity of UVB+UVA, are discussed. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 442–444, 2004;
Comparative study on sensitivity of higher plants and fish to heavy fuel oil
Authors: Kazlauskienė N. , Svecevičius G. , Vosylienė M. Z. , Marčiulionienė D. , Montvydienė D.
Published: July 2004

Laboratory tests were conducted on higher plants [garden cress (Lepidium sativum), great duckweed (Spirodela polyrrhiza), and Tradescantia clone BNL 02] and fish [rainbow trout (Oncorhynchus mykiss) at all stages of development: eggs, larvae and adults] to estimate their sensitivity to heavy fuel oil (HFO). A number of biological indices (survival, growth, and physiological and morphological parameters) as well as the genotoxic impact (Tradescantia) of HFO was evaluated by acute and chronic toxicity tests. Fish were found to be more sensitive to the toxic effect of HFO than were higher plants. EC50 values obtained for higher plants ranged from 8.7 g/L (L. sativum) to 19.8 g/L (Tradescantia), and maximum‐acceptable‐toxicant concentration (MATC) values ranged from 0.1 to 1.0 g/L of total HFO for L. sativum and Tradescantia, respectively. The 96‐h LC50 values ranged from 0.33 g/L, for larvae, to 2.97 g/L, for adult fish, and the MATC value for fish was found to be equal to 0.0042 g/L of total HFO. To evaluate and predict the ecological risk of the overall effects of oil spills, studies should be performed using a set of acute and chronic bioassays that include test species of different phylogenetic levels with the most sensitive morphological, physiological, and genotoxic indices. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 449–451, 2004
Leachate toxicity assessment by responses of algae Nitellopsis obtusa membrane ATPase and cell resting potential, and with Daphtoxkit F™ magna test
Authors: Jurkonienė S. , Maksimov G. , Darginavičienė J. , Sadauskas K. , Vitkus R. , Manusadžianas L.
Published: July 2004

A microscale bioassay based on 50% inhibition of K+, Mg2+‐ATPase activity in a microsomal fraction isolated from Nitellopsis obtusa cells was developed. Compared to that for a plasma membrane fraction purified in a sucrose gradient, the preparation procedure for a microsomal fraction is less time consuming and the yield is substantially higher. Characteristics of the microsomal preparation proved to be similar to those of the highly purified plasma membrane preparation (Manusadžianas et al., 2002), at least for heavy metals. Sensitivity to CuSO4 of the frozen (−8°C) microsomal fraction [49 ± 17 (SD) μM; n = 8] did not significantly differ from that of the freshly isolated one (52 ± 30, n = 8), at least for 40 days. Toxicity of leachate water from Kairiai (northern Lithuania) solid waste landfill was assessed by taking samples from various points including temporary reservoirs and analyzing them immediately after spillage (summer 2002) and after storage for almost 2 years at 4°C–6°C. Two tests with the macrophytic alga Nitellopsis obtusa (Charatox, 45‐min EC50 of resting potential depolarization, and ATPase assay, IC50 of membrane ATPase activity) and one test with the crustacean Daphnia magna (Daphtoxkit F™, 48‐h 50% immobilization) tests were used. In general, all three tests showed successively decreasing values of landfill leachate toxicity with an increasing degree of dilution with surface waters. The possibility of employing preserved algal preparations on demand in test batteries seems to be promising, especially in emergencies. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 403–408, 2004;
Prostatic acid phosphatase degrades lysophosphatidic acid in seminal plasma
Authors: Tanaka Masayuki , Kishi Yasuhiro , Takanezawa Yasukazu , Kakehi Yoshiyuki , Aoki Junken , Arai Hiroyuki
Published: July 2004

Lysophosphatidic acid (LPA) is a lipid mediator with multiple biological activities and is detected in various biological fluids, including human seminal plasma. Due to its cell proliferation stimulatory and anti‐apoptotic activities, LPA has been implicated in the progression of some cancers such as ovarian cancer and prostate cancer. Here, we show that prostatic acid phosphatase, which is a non‐specific phosphatase and which has been implicated in the progression of prostate cancer, inactivates LPA in human seminal plasma. Human seminal plasma contains both an LPA‐synthetic enzyme, lysoPLD, which converts lysophospholipids to LPA and is responsible for LPA production in serum, and its major substrate, lysophosphatidylcholine. In serum, LPA accumulated during incubation at 37 °C. However, in seminal plasma, LPA did not accumulate. This discrepancy is explained by the presence of a strong LPA‐degrading activity. Incubation of LPA with seminal plasma resulted in the disappearance of LPA and an accompanying accumulation of monoglyceride showing that LPA is degraded by phosphatase activity present in the seminal plasma. When seminal plasma was incubated in the presence of a phosphatase inhibitor, sodium orthovanadate, LPA accumulated, indicating that LPA is produced and degraded in the fluid. Biochemical characterization of the LPA‐phosphatase activity identified two phosphatase activities in human seminal plasma. By Western blotting analysis in combination with several column chromatographies, the major activity was revealed to be identical to prostatic acid phosphatase. The present study demonstrates active LPA metabolism in seminal plasma and indicates the possible role of LPA signaling in male sexual organs including prostate cancer.
Capsaicin inhibits the production of tumor necrosis factor α by LPS‐stimulated murine macrophages, RAW 264.7: a PPARγ ligand‐like action as a novel mechanism
Authors: Park Jun-Young , Kawada Teruo , Han In-Seob , Kim Byung-Sam , Goto Tsuyoshi , Takahashi Nobuyuki , Fushiki Tohru , Kurata Tadao , Yu Rina
Published: July 2004

Capsaicin, a major ingredient of hot pepper, is considered to exhibit anti‐inflammatory properties. Our previous study demonstrated that capsaicin inhibited the production of pro‐inflammatory mediators through NF‐κB inactivation in LPS‐stimulated macrophages. In order to further clarify the mechanism underlying the anti‐inflammatory action of capsaicin, we investigated whether capsaicin alters PPARγ activity, which regulates the production of the pro‐inflammatory cytokine TNFα. Capsaicin significantly inhibited the production of TNFα by macrophages in a dose‐dependent manner. Simultaneous exposure of the cells to capsaicin and PPARγ agonist troglitazone or RXR agonist LG100268 resulted in stronger inhibition of TNFα production compared to the cells treated with either capsaicin, troglitazone, or LG100268 alone. Luciferase reporter assay revealed that capsaicin induced GAL4/PPARγ chimera and full length PPARγ (PPRE) transactivations in a dose‐dependent manner. Furthermore, a specific PPARγ antagonist T0070907 abrogated the inhibitory action of capsaicin on LPS‐induced TNFα production by RAW 264.7 cells, indicating that capsaicin acts like a ligand for PPARγ. Our data demonstrate for the first time that the anti‐inflammatory action of capsaicin may be mediated by PPARγ activation in LPS‐stimulated RAW 264.7 cells.
Lowered glucose suppressed the proliferation and increased the differentiation of murine neural stem cells in vitro
Authors: Horie Nobutaka , Moriya Takahiro , Mitome Masato , Kitagawa Naoki , Nagata Izumi , Shinohara Kazuyuki
Published: July 2004

Cerebral ischemia is known to activate endogenous neural stem cells (NSCs), but its mechanisms remain unknown. Since lowered glucose supply seems to mediate ischemic actions, we examined the effect of low glucose on NSC activities in vitro. Low glucose applied during the proliferation period diminished EGF‐induced proliferation of NSCs without affecting subsequent differentiation, but low glucose directly exposed during the differentiation period facilitated the differentiation of NSCs into neurons and astrocytes. These findings suggest that low glucose facilitated NSC differentiation, but it diminished NSC proliferation. Moreover, the effect of low glucose may be dependent on the timing of application.
Feeding induces expression of heat shock proteins that reduce oxidative stress
Authors: Katsuki Kensaku , Fujimoto Mitsuaki , Zhang Xiu-Ying , Izu Hanae , Takaki Eiichi , Tanizawa Yukio , Inouye Sachiye , Nakai Akira
Published: July 2004

Heat shock proteins (Hsps) are induced in response to various kinds of environmental and physiological stresses. However, it is unclear whether Hsps play roles in protecting cells in the digestive organs against xenobiotic chemicals. Here, we found that feeding induces expression of a set of Hsps specifically in the mouse liver and intestine by activating heat shock transcription factor 1 (HSF1). In the liver, HSF1 is required to suppress toxic effects of electrophiles, which are xenobiotic chemicals causing oxidative stress. We found that overexpression of Hsp27, which elevates cellular glutathione level, promotes survival of culture cells exposed to electrophiles. These results suggest a novel mechanism of cell protection against xenobiotic chemicals in the food.
Identification of the catalytic residues in the double‐zinc aminopeptidase from Streptomyces griseus
Authors: Fundoiano-Hershcovitz Yifat , Rabinovitch Larisa , Langut Yael , Reiland Vera , Shoham Gil , Shoham Yuval
Published: July 2004

The aminopeptidase from Streptomyces griseus (SGAP) has been cloned and expressed in Escherichia coli. By growing the cells in the presence of 1 M sorbitol at 18 °C, the protein was obtained in a soluble and active form. The amino acid sequence of the recombinant SGAP contained four amino acids differing from the previously published sequence. Re‐sequencing of the native protein indicated that asparagines 70 and 184 are in fact aspartic acids as in the recombinant protein. Based on the crystal structure of SGAP, Glu131 and Tyr246 were proposed to be the catalytic residues. Replacements of Glu131 resulted in loss of activity of 4–5 orders of magnitude, consistent with Glu131 acting as the general base residue. Mutations in Tyr246 resulted in about 100‐fold reduction of activity, suggesting that this residue is involved in the stabilization of the transition state intermediate.
Stemar‐13‐ene synthase, a diterpene cyclase involved in the biosynthesis of the phytoalexin oryzalexin S in rice
Authors: Nemoto Tadahiro , Cho Eun-Min , Okada Atsushi , Okada Kazunori , Otomo Kazuko , Kanno Yuri , Toyomasu Tomonobu , Mitsuhashi Wataru , Sassa Takeshi , Minami Eiichi , Shibuya Naoto , Nishiyama Makoto , Nojiri Hideaki , Yamane Hisakazu
Published: July 2004

In suspension‐cultured rice cells, diterpenoid phytoalexins are produced in response to exogenously applied elicitors. We isolated a cDNA encoding a diterpene cyclase, OsDTC2, from suspension‐cultured rice cells treated with a chitin elicitor. The OsDTC2 cDNA was overexpressed in Escherichia coli as a fusion protein with glutathione S‐transferase, and the recombinant OsDTC2 was indicated to function as stemar‐13‐ene synthase that converted syn‐copalyl diphosphate to stemar‐13‐ene, a putative diterpene hydrocarbon precursor of the phytoalexin oryzalexin S. The level of OsDTC2 mRNA in suspension‐cultured rice cells began to increase 3 h after addition of the elicitor and reached the maximum after 8 h. The expression of OsDTC2 was also induced in UV‐irradiated rice leaves. In addition, we indicated that stemar‐13‐ene accumulated in the chitin‐elicited suspension‐cultured rice cells and the UV‐irradiated rice leaves.