Sample records for minimum toxic concentration
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Stehly, G.R.; Gingerich, W.H.
1999-01-01
A preliminary evaluation of efficacy and minimum toxic concentration of AQUI-S(TM), a fish anaesthetic/sedative, was determined in two size classes of six species of fish important to US public aquaculture (bluegill, channel catfish, lake trout, rainbow trout, walleye and yellow perch). In addition, efficacy and minimum toxic concentration were determined in juvenile-young adult (fish aged 1 year or older) rainbow trout acclimated to water at 7 ??C, 12 ??C and 17 ??C. Testing concentrations were based on determinations made with range-finding studies for both efficacy and minimum toxic concentration. Most of the tested juvenile-young adult fish species were induced in 3 min or less at a nominal AQUI-S(TM) concentration of 20 mg L-1. In juvenile-young adult fish, the minimum toxic concentration was at least 2.5 times the selected efficacious concentration. Three out of five species of fry-fingerlings (1.25-12.5 cm in length and < 1 year old) were induced in ??? 4.1 min at a nominal concentration of 20 mg L-1 AQUI-S(TM), with the other two species requiring nominal concentrations of 25 and 35 mg L-1 for similar times of induction. Recovery times were ??? 7.3 rain for all species in the two size classes. In fry-fingerlings, the minimum toxic concentration was at least 1.4 times the selected efficacious concentration. There appeared to be little relationship between size of fish and concentrations or times to induction, recovery times and minimum toxic concentration. The times required for induction and for recovery were increased in rainbow trout as the acclimation temperature was reduced.
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6 CFR 27.204 - Minimum concentration by security issue.
Code of Federal Regulations, 2011 CFR
2011-01-01
... Section 27.204 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Chemical Facility Security Program § 27.204 Minimum concentration by security issue. (a) Release Chemicals—(1) Release-Toxic Chemicals. If a release-toxic chemical of interest...
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Venkatarajappa, P
2001-01-01
The toxic effect of Cypermethrin 10 EC (0.125, 0.25 and 0.5%) was estimated in the bodywall and digestive system of the larvae of Oryctes rhinoceros by HPLC after exposing them to different concentrations (0.125, 0.25 and 0.5%). Among the various concentrations used maximum residues were detected in bodywall (0.25%), whereas at higher concentration (0.5%) the residue detected was minimum. The treatment of Cypermethrin was found to be highly toxic upto 12 h of treatment, after which it declined reaching the minimum by 24 h. The residue of Cypermethrin could not be detected in digestive system. The experiments indicate the pesticide get concentrated in the bodywall to a maximum extent.
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Pseudomonas fluorescens' view of the periodic table.
Workentine, Matthew L; Harrison, Joe J; Stenroos, Pernilla U; Ceri, Howard; Turner, Raymond J
2008-01-01
Growth in a biofilm modulates microbial metal susceptibility, sometimes increasing the ability of microorganisms to withstand toxic metal species by several orders of magnitude. In this study, a high-throughput metal toxicity screen was initiated with the aim of correlating biological toxicity data in planktonic and biofilm cells to the physiochemical properties of metal ions. To this end, Pseudomonas fluorescens ATCC 13525 was grown in the Calgary Biofilm Device (CBD) and biofilms and planktonic cells of this microorganism were exposed to gradient arrays of different metal ions. These arrays included 44 different metals with representative compounds that spanned every group of the periodic table (except for the halogens and noble gases). The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum biofilm eradication concentration (MBEC) values were obtained after exposing the biofilms to metal ions for 4 h. Using these values, metal ion toxicity was correlated to the following ion-specific physicochemical parameters: standard reduction-oxidation potential, electronegativity, the solubility product of the corresponding metal-sulfide complex, the Pearson softness index, electron density and the covalent index. When the ions were grouped according to outer shell electron structure, we found that heavy metal ions gave the strongest correlations to these parameters and were more toxic on average than the other classes of the ions. Correlations were different for biofilms than for planktonic cells, indicating that chemical mechanisms of metal ion toxicity differ between the two modes of growth. We suggest that biofilms can specifically counter the toxic effects of certain physicochemical parameters, which may contribute to the increased ability of biofilms to withstand metal toxicity.
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The Toxicity of Nitroguanidine and Photolyzed Nitroguandine to Freshwater Aquatic Organisms
1985-03-01
adjusted for simultaneity using Bonferonni’s correction when appropriate. 1. Algicidal concentration. This ts the lowest concentration tested which causes... algicidal or algistatic effects were observed. A 120 hour EC50 based on growth rates could • not be calculated since, as shown in Table 9, neither dry...Relative Chlorophyll ab Minimum algicidal >3 .75 3c >3,753 concentration Minimum algistatic >3,753 >3,753 ŗ concentration 120 Hr EC50 >3,753 >3,753
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The phototoxicity of phenothiazinium derivatives against Escherichia coli and Staphylococcus aureus.
Phoenix, D A; Sayed, Z; Hussain, S; Harris, F; Wainwright, M
2003-10-24
Phenothiazinium dyes, and derivatives, were tested for toxicity to Escherichia coli and Staphylococcus aureus. The dyes were generally lipophilic (log P>1) and showed inherent dark toxicity (minimum lethal concentrations: 3.1-1000 microM). Dye illumination (total light dose of 3.15 J cm(-1) over 30 min) led to up to eight-fold reductions in minimum lethal concentrations. Most of the illuminated dyes showed significant relative singlet oxygen yields (phi'delta: 0.18-1.35) suggesting a type II mechanism of generating a phototoxic response. Although generally up to six-fold more effective against S. aureus, the dyes tested efficiently killed E. coli and may be of particular use in combating Gram-negative pathogens.
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Spacecraft Minimum Allowable Concentrations: Determination, Application, and Contingency Situations
NASA Technical Reports Server (NTRS)
Marshburn, Thomas H.; Dawson, David L. (Technical Monitor)
1999-01-01
This document is an outline of a presentation about the determination of minimum allowable concentrations in spacecraft. The presentation reviews the type of toxins and mechanisms to determine the acceptable concentrations of these toxic substances. The considerations for the unique situation that spaceflight entails including zero gravity, and the intense scrutiny are reviewed. The current measurement hardware is reviewed. The spacecraft atmospheres on the Shuttle, airflow, the Space Station and the EMU in respect to airflow, pressure, constituents are also summarized. Contingency situations and potential hazards are also discussed.
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A Portable Electronic Nose for Toxic Vapor Detection, Identification, and Quantification
NASA Technical Reports Server (NTRS)
Linnell, B. R.; Young, R. C.; Griffin, T. P.; Meneghelli, B. J.; Peterson, B. V.; Brooks, K. B.
2005-01-01
The Space Program and military use large quantities of hydrazine and monomethyl hydrazine as rocket propellant, which are very toxic and suspected human carcinogens. Current off-the-shelf portable instruments require 10 to 20 minutes of exposure to detect these compounds at the minimum required concentrations and are prone to false positives, making them unacceptable for many operations. In addition, post-mission analyses of grab bag air samples from the Shuttle have confirmed the occasional presence of on-board volatile organic contaminants, which also need to be monitored to ensure crew safety. A new prototype instrument based on electronic nose (e-nose) technology has demonstrated the ability to qualify (identify) and quantify many of these vapors at their minimum required concentrations, and may easily be adapted to detect many other toxic vapors. To do this, it was necessary to develop algorithms to classify unknown vapors, recognize when a vapor is not any of the vapors of interest, and estimate the concentrations of the contaminants. This paper describes the design of the portable e-nose instrument, test equipment setup, test protocols, pattern recognition algorithms, concentration estimation methods, and laboratory test results.
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NASA Astrophysics Data System (ADS)
Wang, Huaimin; Ren, Chunhua; Song, Zhijian; Wang, Ling; Chen, Xuemei; Yang, Zhimou
2010-06-01
We report on the use of a phosphatase to assist the formation of leaf-like structures and a supramolecular hydrogel with an ultra-low minimum gelation concentration. The compound can gel water at a minimum gelation concentration of 0.01 wt%, which is the lowest gelation concentration reported up to now. The images obtained by transmission electron microscopy (TEM) reveal the existence of leaf-like structures serving as the matrix of the hydrogels. The stability of the hydrogels was studied and emission spectra were used to get information about the molecular packing in the leaf-like structures. Since lowering the concentration of the gelator decreases the toxicity of the resulting hydrogels, ultra-low concentration gels have potential uses as biocompatible biomaterials for, e.g., cell cultures, tissue engineering, and drug delivery.
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Pesticide data for selected Wyoming streams, 1976-78
Butler, David L.
1987-01-01
In 1976, the U.S. Geological Survey, in cooperation with the Wyoming Department of Agriculture, started a monitoring program to determine pesticide concentrations in Wyoming streams. This program was incorporated into the water-quality data-collection system already in operation. Samples were collected at 20 sites for analysis of various insecticides, herbicides, polychlorinated biphenyls, and polychlorinated napthalenes.\\The results through 1978 revealed small concentrations of pesticides in water and bottom-material samples were DDE (39 percent of the concentrations equal to or greater than the minimum reported concentrations of the analytical methods), DDD (20 percent), dieldrin (21 percent), and polychlorinated biphenyls (29 percent). The herbicides most commonly found in water samples were 2,4-D (29 percent of the concentrations equal to or greater than the minimum reported concentrations of the analytical method) and picloram (23 percent). Most concentrations were significantly less than concentrations thought to be harmful to freshwater aquatic life based on available toxicity data. However for some pesticides, U.S. Environmental Protection Agency water-quality criteria for freshwater aquatic life are based on bioaccumulation factors that result in criteria concentrations less than the minimum reported concentrations of the analytical methods. It is not known if certain pesticides were present at concentrations less than the minimum reported concentrations that exceeded these criteria.
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2013-05-21
minimum inhibitory concentrations and mammalian cell cytotoxicities. The most promising compound had a low molecular weight, was non-toxic, and abolished... molecular weight, was non-toxic, and abolished bacterial growth at 13 mM, with putative activity against pantetheine-phosphate adenylyltransferase, an...time period. Metabolic genome-scale models of bacteria have provided a computational framework for in silico simulations to evaluate how metabolic
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Building a Better Quaternary Ammonium Compound (QAC): Branched Tetracationic Antiseptic Amphiphiles.
Forman, Megan E; Jennings, Megan C; Wuest, William M; Minbiole, Kevin P C
2016-07-05
Bacteria contaminate surfaces in a wide variety of environments, causing severe problems across a number of industries. In a continuation of our campaign to develop novel antibacterial quaternary ammonium compounds (QACs) as useful antiseptics, we have identified a starting material bearing four tertiary amines, enabling the rapid synthesis of several tris- and tetracationic QACs. Herein we report the synthesis and biological activity of a series of 24 multiQACs deemed the "superT" family, and an investigation of the role of cationic charge in antimicrobial and anti-biofilm activity, as well as toxicity. This class represents the most potent series of QACs reported to date against methicillin-resistant Staphylococcus aureus (MRSA), with minimum inhibitory concentrations (MICs) and minimum biofilm eradication concentrations (MBECs) as low as 0.25 and 25 μm, respectively. Based on the significant cell-surface-charge differences between bacterial and eukaryotic cells, in certain cases we observed excellent efficacy-to-toxicity profiles, exceeding a 100-fold differential. This work further elucidates the chemical underpinnings of disinfectant efficacy versus toxicity based on cationic charge. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Toxicity of copper on the growth of marine microalgae Pavlova sp. and its chlorophyll-a
NASA Astrophysics Data System (ADS)
Purbonegoro, T.; Suratno; Puspitasari, R.; Husna, N. A.
2018-02-01
Marine microalgae is the primary producer at the base of the marine food chain. Their sensitivity to metal contamination provides important information for predicting the environmental impact of pollution. Toxicity testing using marine microalgae Pavlova sp. was carried out to assess the toxicity of copper on the growth and chlorophyll-a content. Results of this study show that adverse effects were observed by the increase of copper concentration. Cell number began to decrease at the lowest concentration (13 μg/L) and reduced drastically at 98 μg/L. Minimum cell number was observed at the highest concentration (890 μg/L). The inhibition concentration (IC50) value of copper for Pavlova sp. was 51.46 μg/L and at concentrations >29 μgL-1 the chlorophyll-a content decreased dramatically compared to the control. A variation in cell size and morphology was also observed at the higher concentration by the increase in the cell size and loss of setae compared to normal cells.
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Long-term (30 days) toxicity of NiO nanoparticles for adult zebrafish Danio rerio
Kovrižnych, Jevgenij A.; Zeljenková, Dagmar; Rollerová, Eva; Szabová, Elena
2014-01-01
Nickel oxide in the form of nanoparticles (NiO NPs) is extensively used in different industrial branches. In a test on adult zebrafish, the acute toxicity of NiO NPs was shown to be low, however longlasting contact with this compound can lead to its accumulation in the tissues and to increased toxicity. In this work we determined the 30-day toxicity of NiO NPs using a static test for zebrafish Danio rerio. We found the 30-day LC50 value to be 45.0 mg/L, LC100 (minimum concentration causing 100% mortality) was 100.0 mg/L, and LC0 (maximum concentration causing no mortality) was 6.25 mg/L for adult individuals of zebrafish. Considering a broad use of Ni in the industry, NiO NPs chronic toxicity may have a negative impact on the population of aquatic organisms and on food web dynamics in aquatic systems. PMID:26038672
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Long-term (30 days) toxicity of NiO nanoparticles for adult zebrafish Danio rerio.
Kovrižnych, Jevgenij A; Sotníková, Ružena; Zeljenková, Dagmar; Rollerová, Eva; Szabová, Elena
2014-03-01
Nickel oxide in the form of nanoparticles (NiO NPs) is extensively used in different industrial branches. In a test on adult zebrafish, the acute toxicity of NiO NPs was shown to be low, however longlasting contact with this compound can lead to its accumulation in the tissues and to increased toxicity. In this work we determined the 30-day toxicity of NiO NPs using a static test for zebrafish Danio rerio. We found the 30-day LC50 value to be 45.0 mg/L, LC100 (minimum concentration causing 100% mortality) was 100.0 mg/L, and LC0 (maximum concentration causing no mortality) was 6.25 mg/L for adult individuals of zebrafish. Considering a broad use of Ni in the industry, NiO NPs chronic toxicity may have a negative impact on the population of aquatic organisms and on food web dynamics in aquatic systems.
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A Portable Electronic Nose For Toxic Vapor Detection, Identification, and Quantification
NASA Technical Reports Server (NTRS)
Linnell, B. R.; Young, R. C.; Griffin, T. P.; Meneghelli, B. J.; Peterson, B. V.; Brooks, K. B.
2005-01-01
A new prototype instrument based on electronic nose (e-nose) technology has demonstrated the ability to identify and quantify many vapors of interest to the Space Program at their minimum required concentrations for both single vapors and two-component vapor mixtures, and may easily be adapted to detect many other toxic vapors. To do this, it was necessary to develop algorithms to classify unknown vapors, recognize when a vapor is not any of the vapors of interest, and estimate the concentrations of the contaminants. This paper describes the design of the portable e-nose instrument, test equipment setup, test protocols, pattern recognition algorithms, concentration estimation methods, and laboratory test results.
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2013-01-01
Background Aquilaria crassna Pierre ex Lecomte has been traditionally used in Thailand for treatment of infectious diseases such as diarrhoea and skin diseases for a long time. The main objectives of this study were to examine antibacterial activity of the Aquilaria crassna leaf extract against Staphylococcus epidermidis and its underlying mechanism. The antioxidant activity and acute toxicity were studied as well. Methods Antioxidant activities were examined by FRAP, ABTS and DPPH scavenging methods. Antibacterial activity was conducted using disc diffusion assay and the minimum inhibitory concentration (MIC) was determined by dilution method. The minimum bactericidal concentration (MBC) was reported as the lowest concentration producing no growth of microbes in the subcultures. Morphological changes of the microbe were observed by scanning electron microscopy, while an inhibitory effect on biofilm formation was evaluated by phase contrast microscopic analysis. Bacterial cell wall integrity was assessed by transmission electron microscopy. Acute toxicity was conducted in accordance with the OECD for Testing of Chemicals (2001) guidelines. Results The extract exhibited considerable antioxidant activity. Staphylococcus epidermidis was susceptible to the extract with the MIC and MBC of 6 and 12 mg/ml, respectively. The extract caused swelling and distortion of bacterial cells and inhibited bacterial biofilm formation. Rupture of bacterial cell wall occurred after treated with the extract for 24 h. Acute toxicity test in mice showed no sign of toxicity or death at the doses of 2,000 and 15,000 mg/kg body weight. Conclusion The aqueous extract of Aquilaria crassna leaves possesses an in vitro antibacterial activity against Staphylococcus epidermidis, with no sign of acute oral toxicity in mice, probably by interfering with bacterial cell wall synthesis and inhibiting biofilm formation. PMID:23962360
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Chen, Xiaojin; Wang, Ting; Lu, Mengmeng; Zhu, Luyan; Wang, Yan; Zhou, WenZhong
2014-01-01
Three tilmicosin-loaded hydrogenated castor oil nanoparticle (TMS-HCO-NP) suspensions of different particle sizes were prepared with different polyvinyl alcohol surfactant concentrations using a hot homogenization and ultrasonic technique. The in vitro release, in vitro antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability study were conducted to evaluate the characteristics of the suspensions. The in vitro tilmicosin release rate, antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability of the suspensions were evaluated. When prepared with polyvinyl alcohol concentrations of 0.2%, 1%, and 5%, the mean diameters of the nanoparticles in the three suspensions were 920±35 nm, 452±10 nm, and 151±4 nm, respectively. The three suspensions displayed biphasic release profiles similar to that of freeze-dried TMS-HCO-NP powders, with the exception of having a faster initial release. Moreover, suspensions of smaller-sized particles showed faster initial release, and lower minimum inhibitory concentrations and minimum bactericidal concentrations. Time-kill curves showed that within 12 hours, the suspension with the 151 nm particles had the most potent bactericidal activity, but later, the suspensions with larger-sized particles showed increased antibacterial activity. None of the three suspensions were cytotoxic at clinical dosage levels. At higher drug concentrations, all three suspensions showed similar concentration-dependent cytotoxicity. The suspension with the smallest-sized particle showed significantly more acute toxicity in mice, perhaps due to faster drug release. All three suspensions exhibited good stability at 4°C and at room temperature for at least 6 months. These results demonstrate that TMS-HCO-NP suspensions can be a promising formulation for tilmicosin, and that nanoparticle size can be an important consideration for formulation development.
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Chen, Xiaojin; Wang, Ting; Lu, Mengmeng; Zhu, Luyan; Wang, Yan; Zhou, WenZhong
2014-01-01
Three tilmicosin-loaded hydrogenated castor oil nanoparticle (TMS-HCO-NP) suspensions of different particle sizes were prepared with different polyvinyl alcohol surfactant concentrations using a hot homogenization and ultrasonic technique. The in vitro release, in vitro antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability study were conducted to evaluate the characteristics of the suspensions. The in vitro tilmicosin release rate, antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability of the suspensions were evaluated. When prepared with polyvinyl alcohol concentrations of 0.2%, 1%, and 5%, the mean diameters of the nanoparticles in the three suspensions were 920±35 nm, 452±10 nm, and 151±4 nm, respectively. The three suspensions displayed biphasic release profiles similar to that of freeze-dried TMS-HCO-NP powders, with the exception of having a faster initial release. Moreover, suspensions of smaller-sized particles showed faster initial release, and lower minimum inhibitory concentrations and minimum bactericidal concentrations. Time-kill curves showed that within 12 hours, the suspension with the 151 nm particles had the most potent bactericidal activity, but later, the suspensions with larger-sized particles showed increased antibacterial activity. None of the three suspensions were cytotoxic at clinical dosage levels. At higher drug concentrations, all three suspensions showed similar concentration-dependent cytotoxicity. The suspension with the smallest-sized particle showed significantly more acute toxicity in mice, perhaps due to faster drug release. All three suspensions exhibited good stability at 4°C and at room temperature for at least 6 months. These results demonstrate that TMS-HCO-NP suspensions can be a promising formulation for tilmicosin, and that nanoparticle size can be an important consideration for formulation development. PMID:24920902
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McShane, Heather V A; Sunahara, Geoffrey I; Whalen, Joann K; Hendershot, William H
2014-07-15
Soil toxicity tests for metal oxide nanoparticles often include micrometer-sized oxide and metal salt treatments to distinguish between toxicity from nanometer-sized particles, non-nanometer-sized particles, and dissolved ions. Test result will be confounded if each chemical form has different effects on soil solution chemistry. We report on changes in soil solution chemistry over 56 days-the duration of some standard soil toxicity tests-in three soils amended with 500 mg/kg Cu as nanometer-sized CuO (nano), micrometer-sized CuO (micrometer), or Cu(NO3)2 (salt). In the CuO-amended soils, the log Cu2+ activity was initially low (minimum -9.48) and increased with time (maximum -5.20), whereas in the salt-amended soils it was initially high (maximum -4.80) and decreased with time (minimum -6.10). The Cu2+ activity in the nano-amended soils was higher than in the micrometer-amended soils for at least the first 11 days, and lower than in the salt-amended soils for at least 28 d. The pH, and dissolved Ca and Mg concentrations in the CuO-amended soils were similar, but the salt-amended soils had lower pH for at least 14 d, and higher Ca and Mg concentrations throughout the test. Soil pretreatments such as leaching and aging prior to toxicity tests are suggested.
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Weyhing-Zerrer, Nadine; Kalb, Roland; Oßmer, Rolf; Rossmanith, Peter; Mester, Patrick
2018-02-01
Increased interest in ionic liquids (ILs) is due to their designable and tunable unique physicochemical properties, which are utilized for a wide variety of chemical and biotechnological applications. ILs containing the tris(pentafluoroethyl)trifluorophosphate ([FAP]) anion have been shown to have excellent hydrolytic, electrochemical and thermal stability and have been successfully used in various applications. In the present study the influence of the cation on the toxicity of the [FAP] anion was investigated. Due to the properties of [FAP] ILs, the IL-toxicity of seven cations with [FAP] compared to [Cl] was examined by determination of minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) on six Gram-positive and six Gram-negative clinically-relevant bacteria. For the first time, to our knowledge, the results provide evidence for a decrease in toxicity with increasing alkyl side-chain length, indicating that the combination of both ions is responsible for this 'reverse side-chain effect'. These findings could portend development of new non-toxic ILs as green alternatives to conventional organic solvents. Copyright © 2017 Elsevier Inc. All rights reserved.
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Zinc and lead detoxifying abilities of humic substances relevant to environmental bacterial species.
Perelomov, L V; Sarkar, Binoy; Sizova, O I; Chilachava, K B; Shvikin, A Y; Perelomova, I V; Atroshchenko, Y M
2018-04-30
The effect of humic substances (HS) and their different fractions (humic acids (HA) and hymatomelanic acids (HMA)) on the toxicity of zinc and lead to different strains of bacteria was studied. All tested bacteria demonstrated a lower resistance to zinc than lead showing minimum inhibitory concentrations of 0.1 - 0.3mM and 0.3-0.5mM, respectively. The highest resistance to lead was characteristic of Pseudomonas chlororaphis PCL1391 and Rhodococcus RS67, while Pseudomonas chlororaphis PCL1391 showed the greatest resistance to zinc. The combined fractions of HS and HA alone reduced zinc toxicity at all added concentrations of the organic substances (50 - 200mgL -1 ) to all microorganisms, while hymatomelanic acids reduced zinc toxicity to Pseudomonas chlororaphis PCL1391 at 200mgL -1 organic concentration only. The HS fractions imparted similar effects on lead toxicity also. This study demonstrated that heavy metal toxicity to bacteria could be reduced through complexation with HS and their fractions. This was particularly true when the metal-organic complexes held a high stability, and low solubility and bioavailability. Copyright © 2018 Elsevier Inc. All rights reserved.
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Singh, Satya S; Singh, Santosh K; Mishra, Arun K
2008-01-01
To study the regulation of Na(+) ion by combined-N sources in Azolla pinnata-Anabaena azollae, Na(+) influx, intracellular Na(+) and Na(+) efflux were investigated in the presence of different N-sources (N(2), NH(4)(+), NO(3)(-) and urea) and various NaCl concentrations. Sodium influx by Azolla pinnata fronds was minimum in the presence of NO(3)(-). Almost identical levels of intracellular sodium, although less than N(2) and NH(4)(+) incubated fronds were observed in the presence of NO(3)(-) and urea. Efflux of sodium was minimum in urea and NO(3)(-) grown fronds. A low residual sodium was observed in the fronds incubated in NO(3)(-) and urea supplemented media. Results suggest that nitrate and urea curtailed the entry of sodium, reduced salt toxicity maximally by maintaining the minimum level of sodium and also conserved energy due to slow influx and efflux of Na(+) within the fronds during salt shock and the process of adaptation.
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1987-01-15
algicidal effect on the * alga. LC50 values for the rainbow trout and the water flea were 2.2% and 9.3% of the stock solution, respectively. Additional...significantly from the initial inoculum level. " Algicidal concentration. This is the lowest concentration tested which causes an apparent algistatic...86.9 - 335.5 mg/L). The minimum algicidal concentration was greater than 542.4 mg/L, the highest concentration tested. When algal cultures from this
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40 CFR 62.14452 - What test methods and procedures must I use?
Code of Federal Regulations, 2010 CFR
2010-07-01
... total dioxin/furan emissions. The minimum sample time must be 4 hours per test run. If you have selected the toxic equivalency standards for dioxin/furans under § 62.14411, you must use the following procedures to determine compliance: (1) Measure the concentration of each dioxin/furan tetra-through octa...
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Developmental phytotoxicity of metal oxide nanoparticles to Arabidopsis thaliana.
Lee, Chang Woo; Mahendra, Shaily; Zodrow, Katherine; Li, Dong; Tsai, Yu-Chang; Braam, Janet; Alvarez, Pedro J J
2010-03-01
Phytotoxicity is an important consideration to understand the potential environmental impacts of manufactured nanomaterials. Here, we report on the effects of four metal oxide nanoparticles, aluminum oxide (nAl(2)O(3)), silicon dioxide (nSiO(2)), magnetite (nFe(3)O(4)), and zinc oxide (nZnO), on the development of Arabidopsis thaliana (Mouse-ear cress). Three toxicity indicators (seed germination, root elongation, and number of leaves) were quantified following exposure to each nanoparticle at three concentrations: 400, 2,000, and 4,000 mg/L. Among these particles, nZnO was most phytotoxic, followed by nFe(3)O(4), nSiO(2), and nAl(2)O(3), which was not toxic. Consequently, nZnO was further studied to discern the importance of particle size and zinc dissolution as toxicity determinants. Soluble zinc concentrations in nanoparticle suspensions were 33-fold lower than the minimum inhibitory concentration of dissolved zinc salt (ZnCl(2)), indicating that zinc dissolution could not solely account for the observed toxicity. Inhibition of seed germination by ZnO depended on particle size, with nanoparticles exerting higher toxicity than larger (micron-sized) particles at equivalent concentrations. Overall, this study shows that direct exposure to nanoparticles significantly contributed to phytotoxicity and underscores the need for eco-responsible disposal of wastes and sludge containing metal oxide nanoparticles.
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Yoo, Yeong Du; Yoon, Eun Young; Jeong, Hae Jin; Lee, Kyung Ha; Hwang, Yeong Jong; Seong, Kyeong Ah; Kim, Jae Seong; Park, Jae Yeon
2013-01-01
Few protistan grazers feed on toxic dinoflagellates, and low grazing pressure on toxic dinoflagellates allows these dinoflagellates to form red-tide patches. We explored the feeding ecology of the newly described heterotrophic dinoflagellate Gyrodinium moestrupii when it fed on toxic strains of Alexandrium minutum, Alexandrium tamarense, and Karenia brevis and on nontoxic strains of A. tamarense, Prorocentrum minimum, and Scrippsiella trochoidea. Specific growth rates of G. moestrupii feeding on each of these dinoflagellates either increased continuously or became saturated with increasing mean prey concentration. The maximum specific growth rate of G. moestrupii feeding on toxic A. minutum (1.60/d) was higher than that when feeding on nontoxic S. trochoidea (1.50/d) or P. minimum (1.07/d). In addition, the maximum growth rate of G. moestrupii feeding on the toxic strain of A. tamarense (0.68/d) was similar to that when feeding on the nontoxic strain of A. tamarense (0.71/d). Furthermore, the maximum ingestion rate of G. moestrupii on A. minutum (2.6 ng C/grazer/d) was comparable to that of S. trochoidea (3.0 ng C/grazer/d). Additionally, the maximum ingestion rate of G. moestrupii on the toxic strain of A. tamarense (2.1 ng C/grazer/d) was higher than that when feeding on the nontoxic strain of A. tamarense (1.3 ng C/grazer/d). Thus, feeding by G. moestrupii is not suppressed by toxic dinoflagellate prey, suggesting that it is an effective protistan grazer of toxic dinoflagellates. © 2012 The Author(s) Journal of Eukaryotic Microbiology © 2012 International Society of Protistologists.
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Sathantriphop, Sunaiyana; Achee, Nicole L; Sanguanpong, Unchalee; Chareonviriyaphap, Theeraphap
2015-12-01
The High Throughput Screening System (HITSS) has been applied in insecticide behavioral response studies with various mosquito species. In general, chemical or natural compounds can produce a range of insect responses: contact irritancy, spatial repellency, knock-down, and toxicity. This study characterized these actions in essential oils derived from citronella, hairy basil, catnip, and vetiver in comparison to DEET and picaridin against Aedes aegypti and Anopheles minimus mosquito populations. Results indicated the two mosquito species exhibited significantly different (P<0.05) contact irritant escape responses between treatment and control for all tested compound concentrations, except with the minimum dose of picaridin (P>0.05) against Ae. aegypti. Spatial repellency responses were elicited in both mosquito species when exposed to all compounds, but the strength of the repellent response was dependent on compound and concentration. Data show that higher test concentrations had greatest toxic effects on both mosquito populations, but vetiver had no toxic effect on Ae. aegypti and picaridin did not elicit toxicity in either Ae. aegypti or An. minimus at any test concentration. Ultimately, this study demonstrates the ability of the HITSS assay to guide selection of effective plant essential oils for repelling, irritating, and killing mosquitoes. © 2015 The Society for Vector Ecology.
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The activity of silver nanoparticles against microalgae of the Prototheca genus.
Jagielski, Tomasz; Bakuła, Zofia; Pleń, Małgorzata; Kamiński, Michał; Nowakowska, Julita; Bielecki, Jacek; Wolska, Krystyna I; Grudniak, Anna M
2018-05-01
To investigate the in vitro activity of silver NPs (AgNPs) against pathogenic microalgae of the Prototheca genus. The antialgal potential of AgNPs against Prototheca species of both clinical and environmental origin was assessed from minimum inhibitory (algistatic) and algicidal concentrations. The in vitro cytotoxicity of AgNPs against bovine mammary epithelial cell line was evaluated by means of the standard MTT assay. AgNPs showed a strong killing activity toward Prototheca algae, as the minimal algicidal concentration (MAC) values matched perfectly the corresponding minimum inhibitory concentration (MIC) values for all species (MAC = MIC, 1-4 mg/l), except P. stagnora (MIC > 8 mg/l). The concentrations inhibitory to pathogenic Prototheca spp. (MIC, 1-4 mg/l) were below the concentrations at which any toxicity in epithelial cells could be observed (CC 20 > 6 mg/l). The study emphasizes the potential of AgNPs as a new therapeutic tool for the management of Prototheca infections.
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Frankel, Mathew L.; Demeter, Marc A.; Lemire, Joe A.; Turner, Raymond J.
2016-01-01
Anthropogenic activities have resulted in the intensified use of water resources. For example, open pit bitumen extraction by Canada’s oil sands operations uses an estimated volume of three barrels of water for every barrel of oil produced. The waste tailings–oil sands process water (OSPW)–are stored in holding ponds, and present an environmental concern as they are comprised of residual hydrocarbons and metals. Following the hypothesis that endogenous OSPW microbial communities have an enhanced tolerance to heavy metals, we tested the capacity of planktonic and biofilm populations from OSPW to withstand metal ion challenges, using Cupriavidus metallidurans, a known metal-resistant organism, for comparison. The toxicity of the metals toward biofilm and planktonic bacterial populations was determined by measuring the minimum biofilm inhibitory concentrations (MBICs) and planktonic minimum inhibitory concentrations (MICs) using the MBEC ™ assay. We observed that the OSPW community and C. metallidurans had similar tolerances to 22 different metals. While thiophillic elements (Te, Ag, Cd, Ni) were found to be most toxic, the OSPW consortia demonstrated higher tolerance to metals reported in tailings ponds (Al, Fe, Mo, Pb). Metal toxicity correlated with a number of physicochemical characteristics of the metals. Parameters reflecting metal-ligand affinities showed fewer and weaker correlations for the community compared to C. metallidurans, suggesting that the OSPW consortia may have developed tolerance mechanisms toward metals present in their environment. PMID:26849649
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Karuppiah, Ponmurugan; Mustaffa, Muhammed
2013-01-01
Objective To investigate different Musa sp. leave extracts of hexane, ethyl acetate and methanol were evaluated for antibacterial activity against multi-drug resistant pathogens causing nosocomial infection by agar well diffusion method and also antioxidant activities. Methods The four different Musa species leaves were extracted with hexane, ethyl acetate and methanol. Antibacterial susceptibility test, minimum inhibitory concentration and minimum inhibitory bacterial concentration were determined by agar well diffusion method. Total phenolic content and in vitro antioxidant activity was determined. Results All the Musa sp. extracts showed moderate antibacterial activities expect Musa paradisiaca with the inhibition zone ranging from 8.0 to 18.6 mm. Among four species ethyl acetate extracts of Musa paradisiaca showed highest activity against tested pathogens particularly E. coli, P. aeruginosa and Citrobacter sp. The minimum inhibitory concentrations were within the value of 15.63- 250 µg/mL and minimum bactericidal concentrations were ranging from 31.25- 250 µg/mL. Antioxidant activity of Musa acuminate exhibited maximum activity among other three Musa species. Conclusions The present study concluded that among the different Musa species, Musa paradisiaca displayed efficient antibacterial activity followed by Musa acuminata against multi-drug resistant nosocomial infection causing pathogens. Further, an extensive study is needed to identify the bioactive compounds, mode of action and toxic effect in vivo of Musa sp. PMID:23998016
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Karuppiah, Ponmurugan; Mustaffa, Muhammed
2013-09-01
To investigate different Musa sp. leave extracts of hexane, ethyl acetate and methanol were evaluated for antibacterial activity against multi-drug resistant pathogens causing nosocomial infection by agar well diffusion method and also antioxidant activities. The four different Musa species leaves were extracted with hexane, ethyl acetate and methanol. Antibacterial susceptibility test, minimum inhibitory concentration and minimum inhibitory bacterial concentration were determined by agar well diffusion method. Total phenolic content and in vitro antioxidant activity was determined. All the Musa sp. extracts showed moderate antibacterial activities expect Musa paradisiaca with the inhibition zone ranging from 8.0 to 18.6 mm. Among four species ethyl acetate extracts of Musa paradisiaca showed highest activity against tested pathogens particularly E. coli, P. aeruginosa and Citrobacter sp. The minimum inhibitory concentrations were within the value of 15.63- 250 µg/mL and minimum bactericidal concentrations were ranging from 31.25- 250 µg/mL. Antioxidant activity of Musa acuminate exhibited maximum activity among other three Musa species. The present study concluded that among the different Musa species, Musa paradisiaca displayed efficient antibacterial activity followed by Musa acuminata against multi-drug resistant nosocomial infection causing pathogens. Further, an extensive study is needed to identify the bioactive compounds, mode of action and toxic effect in vivo of Musa sp.
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Büdingen, Fiona V.; Gonzalez, Daniel; Tucker, Amelia N.
2014-01-01
The liver is a complex organ with great ability to influence drug pharmacokinetics (PK). Due to its wide array of function, its impairment has the potential to affect bioavailability, enterohepatic circulation, drug distribution, metabolism, clearance, and biliary elimination. These alterations differ widely depending on the cause of the liver failure, if it is acute or chronic in nature, the extent of impairment, and comorbid conditions. In addition, the effects on liver functions do not occur in a proportional or predictable manner for escalating degrees of liver impairment. The ability of hepatic alterations to influence PK is also dependent on drug characteristics, such as administration route, chemical properties, protein binding, and extraction ratio, among others. This complexity makes it difficult to predict what effects these changes will have on a particular drug. Unlike certain classes of agents, efficacy of anti-infectives is most often dependent on fulfilling PK/pharmacodynamic targets, such as maximum concentration/minimum inhibitory concentration (Cmax/MIC), area under the curve/minimum inhibitory concentration (AUC/MIC), time above MIC (T>MIC), half-maximal inhibitory concentration (IC50) or half-maximal effective concentration (EC50), or the time above the concentration which inhibits viral replication by 95% (T>EC95). Loss of efficacy and/or an increased risk of toxicity may occur in certain circumstances of liver injury. Although it is important to consider these potential alterations and their effects on specific anti-infectives, many lack data to constitute specific dosing adjustments, making it important to monitor patients for effectiveness and toxicities of therapy. PMID:24949199
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Aristi, I; Casellas, M; Elosegi, A; Insa, S; Petrovic, M; Sabater, S; Acuña, V
2016-05-01
Freshwater ecosystems are threatened by multiple anthropogenic stressors, which might be differentiated into two types: those that reduce biological activity at all concentrations (toxic contaminants), and those that subsidize biological activity at low concentrations and reduce it at high concentrations (assimilable contaminants). When occurring in mixtures, these contaminants can have either antagonistic, neutral or synergistic effects; but little is known on their joint effects. We assessed the interaction effects of a mixture of assimilable and toxic contaminants on stream biofilms in a manipulative experiment using artificial streams, and following a factorial design with three nutrient levels (low, medium or high) and either presence or absence of a mixture of emerging contaminants (ciprofloxacin, erythromycin, diclofenac, methylparaben, and sulfamethoxazole). We measured biofilm biomass, basal fluorescence, gross primary production and community respiration. Our initial hypotheses were that biofilm biomass and activity would: increase with medium nutrient concentrations (subsidy effect), but decrease with high nutrient concentrations (stress effect) (i); decrease with emerging contaminants, with the minimum decrease at medium nutrient concentrations (antagonistic interaction between nutrients subsidy and stress by emerging contaminants) and the maximum decrease at high nutrient concentrations (synergistic interaction between nutrients and emerging contaminants stress) (ii). All the measured variables responded linearly to the available nutrients, with no toxic effect at high nutrient concentrations. Emerging contaminants only caused weak toxic effects in some of the measured variables, and only after 3-4 weeks of exposure. Therefore, only antagonistic interactions were observed between nutrients and emerging contaminants, as medium and high nutrient concentrations partly compensated the harmful effects of emerging contaminants during the first weeks of the experiment. Our results show that contaminants with a subsidy effect can alleviate the effects of toxic contaminants, and that long-term experiments are required to detect stress effects of emerging contaminants at environmentally relevant concentrations. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.
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Biological and surface-active properties of double-chain cationic amino acid-based surfactants.
Greber, Katarzyna E; Dawgul, Małgorzata; Kamysz, Wojciech; Sawicki, Wiesław; Łukasiak, Jerzy
2014-08-01
Cationic amino acid-based surfactants were synthesized via solid phase peptide synthesis and terminal acylation of their α and ε positions with saturated fatty acids. Five new lipopeptides, N-α-acyl-N-ε-acyl lysine analogues, were obtained. Minimum inhibitory concentration and minimum bactericidal (fungicidal) concentration were determined on reference strains of bacteria and fungi to evaluate the antimicrobial activity of the lipopeptides. Toxicity to eukaryotic cells was examined via determination of the haemolytic activities. The surface-active properties of these compounds were evaluated by measuring the surface tension and formation of micelles as a function of concentration in aqueous solution. The cationic surfactants demonstrated diverse antibacterial activities dependent on the length of the fatty acid chain. Gram-negative bacteria and fungi showed a higher resistance than Gram-positive bacterial strains. It was found that the haemolytic activities were also chain length-dependent values. The surface-active properties showed a linear correlation between the alkyl chain length and the critical micelle concentration.
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Habbema, Louis
2010-06-01
Lidocaine toxicity is a potential complication related to using tumescent local anesthesia (TLA) as the exclusive form of pain management in surgical procedures. We sought to determine the minimum concentration of lidocaine in the tumescent solution required to provide adequate anesthesia in patients undergoing liposuction using TLA exclusively. Liposuction using TLA exclusively was performed in 3430 procedures by the same surgeon. The initial concentration of 1000 mg/L lidocaine in the tumescent solution was gradually reduced to find the minimum required for adequate anesthesia. Adequate anesthesia was achieved using a lidocaine concentration of 500 mg/L saline in all areas treated and 400 mg/L saline for most of the areas treated. Data are based on the specific TLA technique used by the same surgeon. Lidocaine serum levels were not analyzed. For patients undergoing liposuction using TLA exclusively, the concentration of lidocaine in the normal saline solution required for adequate anesthesia is 400 mg/L for most body areas and 500 mg/L for some sensitive areas. Copyright 2009 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.
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Development of a general baseline toxicity QSAR model for the fish embryo acute toxicity test.
Klüver, Nils; Vogs, Carolina; Altenburger, Rolf; Escher, Beate I; Scholz, Stefan
2016-12-01
Fish embryos have become a popular model in ecotoxicology and toxicology. The fish embryo acute toxicity test (FET) with the zebrafish embryo was recently adopted by the OECD as technical guideline TG 236 and a large database of concentrations causing 50% lethality (LC 50 ) is available in the literature. Quantitative Structure-Activity Relationships (QSARs) of baseline toxicity (also called narcosis) are helpful to estimate the minimum toxicity of chemicals to be tested and to identify excess toxicity in existing data sets. Here, we analyzed an existing fish embryo toxicity database and established a QSAR for fish embryo LC 50 using chemicals that were independently classified to act according to the non-specific mode of action of baseline toxicity. The octanol-water partition coefficient K ow is commonly applied to discriminate between non-polar and polar narcotics. Replacing the K ow by the liposome-water partition coefficient K lipw yielded a common QSAR for polar and non-polar baseline toxicants. This developed baseline toxicity QSAR was applied to compare the final mode of action (MOA) assignment of 132 chemicals. Further, we included the analysis of internal lethal concentration (ILC 50 ) and chemical activity (La 50 ) as complementary approaches to evaluate the robustness of the FET baseline toxicity. The analysis of the FET dataset revealed that specifically acting and reactive chemicals converged towards the baseline toxicity QSAR with increasing hydrophobicity. The developed FET baseline toxicity QSAR can be used to identify specifically acting or reactive compounds by determination of the toxic ratio and in combination with appropriate endpoints to infer the MOA for chemicals. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Repurposing Salicylanilide Anthelmintic Drugs to Combat Drug Resistant Staphylococcus aureus
Rajamuthiah, Rajmohan; Fuchs, Beth Burgwyn; Conery, Annie L.; Kim, Wooseong; Jayamani, Elamparithi; Kwon, Bumsup; Ausubel, Frederick M.; Mylonakis, Eleftherios
2015-01-01
Staphylococcus aureus is a Gram-positive bacterium that has become the leading cause of hospital acquired infections in the US. Repurposing Food and Drug Administration (FDA) approved drugs for antimicrobial therapy involves lower risks and costs compared to de novo development of novel antimicrobial agents. In this study, we examined the antimicrobial properties of two commercially available anthelmintic drugs. The FDA approved drug niclosamide and the veterinary drug oxyclozanide displayed strong in vivo and in vitro activity against methicillin resistant S. aureus (minimum inhibitory concentration (MIC): 0.125 and 0.5 μg/ml respectively; minimum effective concentration: ≤ 0.78 μg/ml for both drugs). The two drugs were also effective against another Gram-positive bacteria Enterococcus faecium (MIC 0.25 and 2 μg/ml respectively), but not against the Gram-negative species Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter aerogenes. The in vitro antimicrobial activity of niclosamide and oxyclozanide were determined against methicillin, vancomycin, linezolid or daptomycin resistant S. aureus clinical isolates, with MICs at 0.0625-0.5 and 0.125-2 μg/ml for niclosamide and oxyclozanide respectively. A time-kill study demonstrated that niclosamide is bacteriostatic, whereas oxyclozanide is bactericidal. Interestingly, oxyclozanide permeabilized the bacterial membrane but neither of the anthelmintic drugs exhibited demonstrable toxicity to sheep erythrocytes. Oxyclozanide was non-toxic to HepG2 human liver carcinoma cells within the range of its in vitro MICs but niclosamide displayed toxicity even at low concentrations. These data show that the salicylanilide anthelmintic drugs niclosamide and oxyclozanide are suitable candidates for mechanism of action studies and further clinical evaluation for treatment of staphylococcal infections. PMID:25897961
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Effects of a fire-retardant chemical to fathead minnows in experimental streams
Calfee, R.D.; Little, E.E.
2003-01-01
Background. Each year millions of liters of fire-retardant chemicals are applied to wildfires across the nation. Recent laboratory studies with long-term fire-retardant chemicals indicate a significant photoenhanced toxicity of products containing sodium ferrocyanide corrosion inhibitors. Our objective of this study was to determine the toxicity of fire-retardant chemicals to fathead minnows during exposure in experimental outdoor streams. Methods. Stream tests were conducted to determine the potential toxicity of a pulse of exposure as might occur when fire retardant chemical is rinsed from the watershed by rainfall. Two artificial 55-meter experimental streams were dosed with different concentrations of Fire-Trol?? GTS-R, or uncontaminated for a control. Replicate groups of fathead minnows were added to screened containers (10 fish per container) and exposed to retardant chemicals in the recirculating flow of the stream for up to 6 hours. Results and Discussion. Under field conditions toxicity of GTS-R only occurred in the presence of sunlight. When GTS-R was tested on sunny days, 100% mortality occurred. However, when tested during heavily overcast conditions, no mortality occurred. Conclusions. Lethal concentrations of cyanide were measured when GTS-R with YPS exposures were conducted under sunny conditions, but not under cloudy conditions, indicating that a minimum UV level is necessary to induce toxicity as well as the release of cyanide from YPS. The toxicity observed with GTS-R was likely associated with lethal concentrations of cyanide. Rainwater runoff following applications of this fire-retardant at the recommended rate could result in lethal concentrations in small ponds and streams receiving limited water flow under sunny conditions. Recommendations and Outlook. In addition to avoiding application to aquatic habitats, it is important to consider characteristics of the treated site including soil binding affinity and erosive properties.
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2013-01-01
Background Despite universal acceptance that smoking is harmful, a substantial number of adults continue to smoke. The development of potential reduced exposure products (more recently termed modified risk tobacco products) has been suggested as a way to reduce the risks of tobacco smoking. This trial is designed to investigate whether changes in toxicant exposure after switching from a commercial to reduced toxicant prototype (RTP) cigarette (7 mg International Organisation for Standardisation (ISO) tar yield) can be assessed by measurement of biomarkers and other factors. The primary objective is to descriptively assess changes in selected biomarkers of exposure (BoE) and biomarkers of biological effect (BoBE) within participants and within and between groups after switching. Secondary objectives are to assess similarly changes in other biomarkers, quality of life, smoking behaviours, physiological measures, mouth-level exposure to toxicants and sensory perception. Methods/design This trial will assess current smokers, ex-smokers and never-smokers in a single-centre single-blind, controlled clinical trial with a forced-switching design and in-clinic (residential) and ambulatory (non-residential) periods. Smokers will be aged 23–55 years (minimum legal smoking age plus 5 years) and non-smokers 28–55 years (minimum legal smoking age plus 5 years, plus minimum 5 years since last smoked). Smokers will be allowed to smoke freely at all times. We will assess changes in selected BoE and BoBE and effective dose in urine and blood after switching. Creatinine concentrations in serum, creatinine clearance in urine, cotinine concentration in saliva, diaries and collection of spent cigarette filters will be used to assess compliance with the study protocol. Mouth-level exposure to toxins will be assessed by filter analysis. Discussion Data from this study are expected to improve scientific understanding of the effects of RTP cigarettes on BoE and BoBE, and give insights into study design for clinical assessment of potential MRTPs. Trial registration The study was registered in the Current Controlled Trials database under the reference ISRCTN81286286. PMID:23895296
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Shepperd, Christopher J; Newland, Nik; Eldridge, Alison; Graff, Don; Meyer, Ingo
2013-07-29
Despite universal acceptance that smoking is harmful, a substantial number of adults continue to smoke. The development of potential reduced exposure products (more recently termed modified risk tobacco products) has been suggested as a way to reduce the risks of tobacco smoking. This trial is designed to investigate whether changes in toxicant exposure after switching from a commercial to reduced toxicant prototype (RTP) cigarette (7 mg International Organisation for Standardisation (ISO) tar yield) can be assessed by measurement of biomarkers and other factors. The primary objective is to descriptively assess changes in selected biomarkers of exposure (BoE) and biomarkers of biological effect (BoBE) within participants and within and between groups after switching. Secondary objectives are to assess similarly changes in other biomarkers, quality of life, smoking behaviours, physiological measures, mouth-level exposure to toxicants and sensory perception. This trial will assess current smokers, ex-smokers and never-smokers in a single-centre single-blind, controlled clinical trial with a forced-switching design and in-clinic (residential) and ambulatory (non-residential) periods. Smokers will be aged 23-55 years (minimum legal smoking age plus 5 years) and non-smokers 28-55 years (minimum legal smoking age plus 5 years, plus minimum 5 years since last smoked). Smokers will be allowed to smoke freely at all times. We will assess changes in selected BoE and BoBE and effective dose in urine and blood after switching. Creatinine concentrations in serum, creatinine clearance in urine, cotinine concentration in saliva, diaries and collection of spent cigarette filters will be used to assess compliance with the study protocol. Mouth-level exposure to toxins will be assessed by filter analysis. Data from this study are expected to improve scientific understanding of the effects of RTP cigarettes on BoE and BoBE, and give insights into study design for clinical assessment of potential MRTPs. The study was registered in the Current Controlled Trials database under the reference ISRCTN81286286.
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Vlamis, Aristidis; Katikou, Panagiota; Rodriguez, Ines; Rey, Verónica; Alfonso, Amparo; Papazachariou, Angelos; Zacharaki, Thetis; Botana, Ana M.; Botana, Luis M.
2015-01-01
During official shellfish control for the presence of marine biotoxins in Greece in year 2012, a series of unexplained positive mouse bioassays (MBA) for lipophilic toxins with nervous symptomatology prior to mice death was observed in mussels from Vistonikos Bay–Lagos, Rodopi. This atypical toxicity coincided with (a) absence or low levels of regulated and some non-regulated toxins in mussels and (b) the simultaneous presence of the potentially toxic microalgal species Prorocentrum minimum at levels up to 1.89 × 103 cells/L in the area’s seawater. Further analyses by different MBA protocols indicated that the unknown toxin was hydrophilic, whereas UPLC-MS/MS analyses revealed the presence of tetrodotoxins (TTXs) at levels up to 222.9 μg/kg. Reviewing of official control data from previous years (2006–2012) identified a number of sample cases with atypical positive to asymptomatic negative MBAs for lipophilic toxins in different Greek production areas, coinciding with periods of P. minimum blooms. UPLC-MS/MS analysis of retained sub-samples from these cases revealed that TTXs were already present in Greek shellfish since 2006, in concentrations ranging between 61.0 and 194.7 μg/kg. To our knowledge, this is the earliest reported detection of TTXs in European bivalve shellfish, while it is also the first work to indicate a possible link between presence of the toxic dinoflagellate P. minimum in seawater and that of TTXs in bivalves. Confirmed presence of TTX, a very heat-stable toxin, in filter-feeding mollusks of the Mediterranean Sea, even at lower levels to those inducing symptomatology to humans, indicates that this emerging risk should be seriously taken into account by the EU to protect the health of shellfish consumers. PMID:26008234
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Roychoudhury, Shubhadeep; Massanyi, Peter; Bulla, Jozef; Choudhury, Manabendra Dutta; Lukac, Norbert; Filipejova, Terezia; Trandzik, Jozef; Toman, Robert; Almasiova, Viera
2010-09-01
In this study the effect of cadmium on various parameters of spermatozoa motility, morphology as well as on the spermatozoa membrane integrity in rabbits was analyzed in vitro, experimental concentrations ranging from 0.62 to 0.98 micro g CdCl(2)/mL. Pooled rabbit (n = 5) semen was cultured in vitro with cadmium and subsequently diluted to various experimental concentrations apart from control which received no cadmium exposure. Using computer assisted semen analysis method (CASA) we detected decrease of total motility with in the higher concentration range at Time 0. However, with increasing time (after 1 and 2 h of culture), cadmium exerted deleterious effect leading to significant motility reduction in comparison to control. A similar trend was exhibited in case of progressive motility, too. Most of the spermatozoa distance and velocity parameters detected no significant change in comparison to control at the beginning of culture (Time 0), although the toxic effect became significant (P < 0.05) with the passage of culture time (Times 1 and 2 h) in all concentrations. Analysis of spermatozoa morphology detected significant (P < 0.05) alterations at higher concentrations. At higher concentrations acrosomal changes, head without flagellum/separated flagellum, broken flagellum and other abnormalities were significantly higher (P < 0.05), while knob-twisted flagellum and small heads differed significantly (P < 0.05) in comparison to control at all concentrations. In regards to flagellum torso, flagellum ball and retention of cytoplasmic drop statistically higher values (P < 0.05) were noted at the maxium experimental concentration only. Annexin analysis for detection of spermatozoa with disordered membranes revealed higher occurrence of positive spermatozoa in cadmium exposed groups. Annexin-positive reactions suggested alterations in anterior part of head (acrosome) and in flagellum (mitochondrial segment) of spermatozoa. This paper underlines that cadmium is highly toxic for rabbit spermatozoa, as visualized by the toxic effects on parameters of spermatozoa motility, morphology and membrane integrity. The toxic effect is more drastic at higher concentrations. This study also indicates that cadmium requires a minimum one hour incubation time to exert its deletorious effects on various parameters of spermatozoa, particularly at low concentrations.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Douglas, W.S.; Horne, M.T.
1997-10-01
The importance of salinity in whole effluent toxicity tests using marine organisms has been acknowledged in most testing protocols. However, little if any attention has been given to the specific effects of alteration of the ionic composition of seawater solutions to the test organism. The presence of persistent toxicity in effluents with no apparent toxic agents prompted examination of the potential influence of essential ions on the survival of the opossum shrimp, Mysidopsis bahia, a common effluent toxicity indicator organism. Through stepwise additions of ionic salts to deionized water, the minimum complement of salts to maintain survival of M. bahiamore » during 96-h exposures was determined to be Ca, Mg, K, Br, Na, and Cl. The toxicity curves for Ca, Mg, K, and Br were then determined across test salinity ranging from 10 to 35 parts per thousand. These curves for Ca, Mg, and K revealed that there are significant negative effects on survival when the essential ions are present in either low or high concentrations relative to the levels in natural seawater. Although there were no statistically detectable effects of Br on organism survival over the concentration range tested (5--480 mg/L). Br toxicity at concentrations less than 5 mg/L and greater than 700 mg/L have been shown in other studies. In addition, the tolerance ranges for K, Ca, and Mg were shown to shift significantly with changes in salinity, with lower salinity causing an apparent decrease in tolerance to an excess of essential ions. Tests with toxic effluents from five industrial and municipal sources revealed that adjustment of the ionic balance prior to testing reduced or eliminated toxicity in four of the five whole effluents tested. Suggestions for integrating this information into biomonitoring programs and toxicity identification evaluations are presented.« less
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Toxicity tests, antioxidant activity, and antimicrobial activity of chitosan
NASA Astrophysics Data System (ADS)
Kurniasih, M.; Purwati; Dewi, R. S.
2018-04-01
Chitosan is a naturally occurring cationic biopolymer, obtained by alkaline deacetylation of chitin. This research aims to investigate the toxicity, antioxidant activity and antibacterial activity of chitosan from shrimp chitin. In this study, chitin extracted from shrimp waste material. Chitin is then deacetylation with 60% NaOH so that chitosan produced. Degrees of deacetylation, molecular weight, toxicity test, antioxidant activity and antimicrobial activity of chitosan then evaluated. Toxicity test using Brine Shrimp Lethality Test. The antioxidant analysis was performed using DPPH method (2, 2-diphenyl-1-picrylhydrazyl) and FTC method (ferric thiocyanate) in which the radical formed will reduce Ferro to Ferri resulting in a complex with thiocyanate. To determine the antibacterial activity of Staphylococcus aureus, antifungal in Candida albicans and Aspergillus niger by measuring antimicrobial effects and minimum inhibitory concentrations (MIC). Based on the result of research, the value of degrees of deacetylation, molecular weight, and LC50 values of chitosan synthesis was 94,32, 1052.93 g/mol and 1364.41 ppm, respectively. In general, the antioxidative activities increased as the concentration of chitosan increased. MIC value of chitosan against S. aureus, C. albicans, and A. niger was 10 ppm, 15.6 ppm, and 5 ppm, respectively.
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Minimum Release of Tributyltin to Prevent Macrofouling
1990-10-01
MATERIALS AND METHODS The test system used was designed to pump a known volume of a tributyltin ( TBT ) solution of known concentration through a porous...Thain, J.E., M.J. Waldock, and M.E. Wait, Toxicity and degradation studies of Tributyltin ( TBT ) and Dibutyltin (DBT) in the aquatic environment, in...ELEMENT NO NO NO ACCESSION NO 11 TITLE (Include Security Classification) nimum Release of Tributyltin to Prevent Macrofoulinq 12 PERSONAL AUTHOR(S
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Predicting subtle behavioral responses of invertebrates to soil contaminants
DOE Office of Scientific and Technical Information (OSTI.GOV)
Donkin, S.G.
1995-12-31
At concentration levels well below those which cause death and injury to soil invertebrates, a toxic chemical plume may yet effectively damage a soil ecosystem by triggering avoidance behavior among sensitive invertebrates as they move along the concentration gradient. The result may be a soil ecosystem lacking the benefits of effective nutrient cycling and mineralization which a thriving invertebrate population provides. While determining actual detection limits of invertebrates for chemical gradients in soils is experimentally difficult, theoretical calculations have suggested that such limits may be extremely low, and hence many organisms may sense and avoid concentrations of chemicals far belowmore » levels commonly considered acceptable. The minimum gradient (G) that can be detected by a receptor depends on the receptor radius (R), the chemical concentration (C), the diffusion constant of the chemical (D), the velocity of the organism (v), and the time over which the receptor integrates the chemical signal (t). In addition, the characteristics of that gradient are determined by interactions between the chemical and the soil particles (sorption/desorption), and advection through the pore spaces. The example of lead (Pb), a neurotoxic metal with demonstrated behavioral effects on the free-living nematode Caenorhabditis elegans, is used to model a chemical migrating through a soil. Based on experimentally determined Pb concentrations which elicited avoidance behavior in nematodes, and sorption characteristics of defined Pb-soil systems, the minimum detectable gradient (G) produced by a solubilized Pb plume in several soils was modeled. The results predict maximum allowable Pb levels in a soil if a healthy invertebrate community is desired, and suggest areas for further research into the subtle behavioral effects of environmental toxicants ore sensitive invertebrates.« less
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Yang, Shih-Chun; Aljuffali, Ibrahim A; Sung, Calvin T; Lin, Chwan-Fwu; Fang, Jia-You
2016-03-01
Here we evaluated the antibacterial efficacy of soyaethyl morpholinium ethosulfate (SME) micelles as an inherent bactericide against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). The antimicrobial activity was examined by in vitro culture model and murine model of skin infection. Cationic micelles formed by benzalkonium chloride or cetylpyridinium chloride were used for comparison. The minimum inhibitory concentration and minimum bactericidal concentration against S. aureus and MRSA were 1.71-3.42 and 1.71-6.84 μg/ml, respectively. Topical administration of SME micelles significantly decreased the cutaneous infection and MRSA load in mice. The killing of bacteria was caused by direct cell wall/membrane rupture. SME micelles also penetrated into the bacteria to elicit a Fenton reaction and oxidative stress. SME micelles have potential as antimicrobial agents due to their lethal effect against S. aureus and MRSA with a low toxicity to mammalian cells.
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Loughlin, R; Gilmore, B F; McCarron, P A; Tunney, M M
2008-04-01
The aim of this study was to compare both the antimicrobial activity of terpinen-4-ol and tea tree oil (TTO) against clinical skin isolates of meticillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (CoNS) and their toxicity against human fibroblast cells. Antimicrobial activity was compared by using broth microdilution and quantitative in vitro time-kill test methods. Terpinen-4-ol exhibited significantly greater bacteriostatic and bactericidal activity, as measured by minimum inhibitory and bactericidal concentrations, respectively, than TTO against both MRSA and CoNS isolates. Although not statistically significant, time-kill studies also clearly showed that terpinen-4-ol exhibited greater antimicrobial activity than TTO. Comparison of the toxicity of terpinen-4-ol and TTO against human fibroblasts revealed that neither agent, at the concentrations tested, were toxic over the 24-h test period. Terpinen-4-ol is a more potent antibacterial agent against MRSA and CoNS isolates than TTO with neither agent exhibiting toxicity to fibroblast cells at the concentrations tested. Terpinen-4-ol should be considered for inclusion as a single agent in products formulated for topical treatment of MRSA infection. However, further work would initially be required to ensure that resistance would not develop with the use of terpinen-4-ol as a single agent.
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[The presence of medications in the water cycle].
van der Hoek, Jan Peter; van Alphen, Jacques; Kaas, Reinoutje; van der Oost, Ron
2013-01-01
Medications and radiographic contrast dyes are sometimes detected in surface waters, ground water and drinking water; these have proven detrimental effects on organisms living in such waters The concentration of medications found in drinking water is at least a thousand times below their minimum therapeutic dosages. In humans, the long-term effects of daily exposure to low dosages of medications and 'mixture toxicity' is not known; based on the concentrations and substance toxicity, it is presumed that the risk is nil.. Physicians can play their part in controlling the problem of medications becoming part of the water cycle by taking this into account when prescribing medications. Users can make a difference by handling their medications with care and by returning all unused portions to the pharmacy. The pharmaceutical industry can also do its part by taking degradability, options for removal and the environmental effects of medications into account during their stages of development.
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Chavan, Yogita V; Singhal, Rekha S
2013-08-15
Areca nut (Areca catechu L.) or betel nut, a commercial cash crop, is a rich source of polyphenols but also contains toxic alkaloids, mainly arecoline. Separation of these bioactive polyphenols from toxic constituents could propel the safe and beneficial use of betel nut; also it will help arecanut processing industries to produce arecoline-free products. With the aim to develop an effective method for maximum extraction of polyphenols with minimum arecoline, several factors such as nature of the solvent, pH (2-10), substrate concentration (6-14 %) and extraction time (30-150 min) under shaking conditions were evaluated. Qualitative analysis was done using spectrophotometry and high-performance liquid chromatography (HPLC). Maximum extraction of polyphenols (407.47 mg GAE g(-1)), total tannin and its antioxidant activity with minimum arecoline (1.73 mg g(-1) of sample) was achieved by using 80% acetone at pH 4 for 90 min with 10% w/v substrate under shaking conditions. Solvent extraction under optimized parameters gave maximum polyphenols with minimum extraction of arecoline, and highest ratio of polyphenols to arecoline. HPLC and liquid chromatography-mass spectrometry results confirmed the presence of catechin and epicatechin in the extract, which suggests its potential as a source of bioactives. © 2013 Society of Chemical Industry.
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Lipok, Jacek; Studnik, Hanna; Gruyaert, Steven
2010-10-01
The toxicity of commercial formulation of Roundup® 360 SL, widely used, nonselective herbicide and its main constituents, glyphosate (PMG), equimolar (1:1) isopropylamine salt of glyphosate (GIPA) and isopropylamine (IPA) was examined towards eight aquatic microphotoautotrophs; seven cyanobacterial strains representing either saline or freshwater communities, and common eukaryotic algae Chlorella vulgaris Beijerinck. Autotrophs were cultured 21 days in their appropriate standard media supplemented with various amounts of Roundup®, glyphosate, GIPA and IPA. The determination of the growth of examined photoautotrophs was performed by time-course measurements of total chlorophyll content in experimental cultures. The growth rates related to corresponding concentrations of chemicals, the EC(50) values and generation doubling time were determined in order to present the toxicity Roundup® 360 SL formulation and its main constituents. Market available formulation of Roundup® was found to possess toxicity significantly higher than this, attributed to its main constituents; however both these compounds, isopropylamine and glyphosate, also inhibited the growth of examined strains in a dose-dependent manner. Notably, the interpretation of toxicity of the examined substances was found to be significantly dependent on the method of EC(50) calculation. The choice of molar or weight concentration of substances tested separately and in specific formulation was found to be essential in this matter. Due to these findings the EC(50) values were calculated based either on molar or on weight concentrations. Considering Roundup® 360 SL formulation, these values ranged from 10(-3) up to 10(-1) mM and they were one order of magnitude lower than those found for isopropylamine. Quite surprisingly the minimum EC(50) values found for glyphosate did not reach micromolar concentrations, whereas most of the EC(50) values revealed to IPA did not exceed this range. Notably, in all the cases except for Synechocystis aquatilis Sauvageau, isopropylamine alone was indicated as more toxic than glyphosate. Copyright © 2010 Elsevier Inc. All rights reserved.
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40 CFR 257.25 - Assessment monitoring program.
Code of Federal Regulations, 2012 CFR
2012-07-01
...) Minimum distance between upgradient edge of the unit and downgradient monitoring well screen (minimum... that is likely to be without appreciable risk of deleterious effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or...
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40 CFR 257.25 - Assessment monitoring program.
Code of Federal Regulations, 2013 CFR
2013-07-01
...) Minimum distance between upgradient edge of the unit and downgradient monitoring well screen (minimum... that is likely to be without appreciable risk of deleterious effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or...
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40 CFR 257.25 - Assessment monitoring program.
Code of Federal Regulations, 2011 CFR
2011-07-01
...) Minimum distance between upgradient edge of the unit and downgradient monitoring well screen (minimum... that is likely to be without appreciable risk of deleterious effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or...
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Selection of a battery of rapid toxicity sensors for drinking water evaluation.
van der Schalie, William H; James, Ryan R; Gargan, Thomas P
2006-07-15
Comprehensive identification of chemical contaminants in Army field water supplies can be a lengthy process, but rapid analytical methods suitable for field use are limited. A complementary approach is to directly measure toxicity instead of individual chemical constituents. Ten toxicity sensors utilizing enzymes, bacteria, or vertebrate cells were tested to determine the minimum number of sensors that could rapidly identify toxicity in water samples containing one of 12 industrial chemicals. The ideal sensor would respond at a concentration just exceeding the Military Exposure Guideline (MEG) level for the chemical (an estimated threshold for adverse effects) but below the human lethal concentration. Chemical solutions were provided to testing laboratories as blind samples. No sensors responded to deionized water blanks, and only one sensor responded to a hard water blank. No single toxicity sensor responded to more than six chemicals in the desired response range, and one chemical (nicotine) was not detected by any sensor with the desired sensitivity. A combination of three sensors (Microtox, the Electric Cell Substrate Impedance Sensing (ECIS) test, and the Hepatocyte low density lipoprotein (LDL) uptake test) responded appropriately to nine of twelve chemicals. Adding a fourth sensor (neuronal microelectrode array) to the test battery allowed detection of two additional chemicals (aldicarb and methamidophos), but the neuronal microelectrode array was overly sensitive to paraquat. Evaluating sensor performance using a standard set of chemicals and a desired sensitivity range provides a basis both for selecting among available toxicity sensors and for evaluating emerging sensor technologies. Recommendations for future toxicity sensor evaluations are discussed.
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Buckler, Denny R., Foster L. Mayer, Mark R. Ellersieck and Amha Asfaw. 2003. Evaluation of Minimum Data Requirements for Acute Toxicity Value Extrapolation with Aquatic Organisms. EPA/600/R-03/104. U.S. Environmental Protection Agency, National Health and Environmental Effects Re...
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Jiang, Zhibing; Liao, Yibo; Liu, Jingjing; Shou, Lu; Chen, Quanzhen; Yan, Xiaojun; Zhu, Genhai; Zeng, Jiangning
2013-11-15
Six cruises were conducted in a fish farm adjacent to the Ninghai Power Plant in Xiangshan Bay, East China Sea. Fish farming significantly increased NH4(+), DIP, and TOC concentrations, while it significantly decreased the DO level. These increase/decrease trends were more pronounced in warmer seasons. Although culture practices did not significantly increase phytoplankton density, it drastically enhanced dinoflagellate abundance and domination. Significant differences in species diversity and community composition between the cages and the control area were also observed. Temperature elevation caused by thermal discharge associated with eutrophication resulted in a dominant species shift from diatoms alone to dinoflagellates and diatoms. This is the first report of stress-induced toxic dinoflagellate (Prorocentrum minimum) blooms in winter and the winter-spring transition in this bay. Therefore, the effects of aquaculture activity and power plant construction in such a eutrophic, semi-enclosed bay require further attention. Copyright © 2013 Elsevier Ltd. All rights reserved.
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Pandey, Abhay K; Palni, Uma T; Tripathi, Nijendra N
2013-05-01
The present study aimed to evaluate the antifungal activity of 30 essential oils against four dominant fungi Aspergillus flavus Link., A. niger van Tieghem, A. ochraceus Wilhelm and A. terreus Thom of stored pigeon pea seeds at a concentration of 0.36 µL mL(-1). Various fungitoxic properties, such as minimum inhibitory concentration, minimum fungicidal concentration and fungitoxic spectrum, of the most potent oil were determined. The efficacy of the most potent oil in preservation of pigeon pea seeds for 6 months was also carried out by storing 1 kg of seeds in the oil vapour. Clausena pentaphylla and Citrus limon oils were more effective against all the fungi tested, which exhibited 100% per cent mycelial inhibition. The minimum inhibitory concentration of C. pentaphylla oil was determined as 0.07 µL mL(-1) against all the test fungi and was found to be more toxic than Citrus limon oil. C. pentaphylla oil exhibited a broad range of fungitoxicity against 16 other storage fungi of pigeon pea seeds. C. pentaphylla oil significantly protected 1 kg seeds of pigeon pea from fungal deterioration and was superior to synthetic fumigants. The oil did not show any phytotoxicity and the protein content of the seeds was significantly retained for up to 6 months of storage. Thus, C. pentaphylla oil may be used as an effective fumigant in the ecofriendly management of storage fungi of pigeon pea seeds. © 2012 Society of Chemical Industry.
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Inhaled Antibiotics for Ventilator-Associated Infections.
Palmer, Lucy B
2017-09-01
Multidrug-resistant organisms are creating a challenge for physicians treating the critically ill. As new antibiotics lag behind the emergence of worsening resistance, intensivists in countries with high rates of extensively drug-resistant bacteria are turning to inhaled antibiotics as adjunctive therapy. These drugs can provide high concentrations of drug in the lung that could not be achieved with intravenous antibiotics without significant systemic toxicity. This article summarizes current evidence describing the use of inhaled antibiotics for the treatment of bacterial ventilator-associated pneumonia and ventilator-associated tracheobronchitis. Preliminary data suggest aerosolized antimicrobials may effectively treat resistant pathogens with high minimum inhibitory concentrations. Copyright © 2017 Elsevier Inc. All rights reserved.
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Mebane, Christopher A.
2015-01-01
Criticisms of the uses of the no-observed-effect concentration (NOEC) and the lowest-observed-effect concentration (LOEC) and more generally the entire null hypothesis statistical testing scheme are hardly new or unique to the field of ecotoxicology [1-4]. Among the criticisms of NOECs and LOECs is that statistically similar LOECs (in terms of p value) can represent drastically different levels of effect. For instance, my colleagues and I found that a battery of chronic toxicity tests with different species and endpoints yielded LOECs with minimum detectable differences ranging from 3% to 48% reductions from controls [5].
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Mogensen, Stine; Sverrisdóttir, Eva; Sveinsdóttir, Kolbrún; Treldal, Charlotte; Jensen, Kenneth; Jensen, Anders Bonde; Kristensen, Claus Andrup; Jacobsen, Jette; Kreilgaard, Mads; Petersen, Janne; Andersen, Ove
2017-01-01
The aim was to investigate systemic exposure after administration of a novel bupivacaine lozenge in healthy individuals with normal mucosa and in head and neck cancer (HNC) patients with oral mucositis. A lozenge containing 5, 10, 25 and 50 mg bupivacaine, respectively, was administered as single dose to 10 healthy individuals, and a lozenge containing 25 mg bupivacaine was administered as single dose to 10 HNC patients with oral mucositis and as multiple doses to five patients with HNC. Blood samples were collected for 6 hr from the healthy individuals and 3 hr from the patients with HNC, respectively, after administration. The plasma concentration-time profiles of bupivacaine were fitted to pharmacokinetic models using nonlinear mixed-effects modelling, evaluating demographics and health status as covariates. The population pharmacokinetics (PK) of bupivacaine lozenge was best described by a two-compartment distribution model with absorption transit compartments. All the observed plasma concentrations were well below the bupivacaine concentrations (2000-2250 ng/ml) which have caused toxic symptoms. The PK model suggested that relative bioavailability was two times higher in HNC patients with oral mucositis grade 1-2 and three times higher in HNC patients with oral mucositis grade 3-4 than in the healthy individuals. Simulations showed that the plasma concentrations would be below the toxic limit after repeated dosing every second hour with 25 mg bupivacaine for five days. The 25-mg bupivacaine lozenges were safe without systemic toxic levels of bupivacaine or risk of side effects. Based on PK simulations of repeated doses of 25 mg every two hours for 16 hr a day, the lozenges can be administered with minimum risk of exceeding the toxic limit. © 2016 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).
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Roy, Ranita; Tiwari, Monalisa; Donelli, Gianfranco; Tiwari, Vishvanath
2018-01-01
ABSTRACT Biofilm refers to the complex, sessile communities of microbes found either attached to a surface or buried firmly in an extracellular matrix as aggregates. The biofilm matrix surrounding bacteria makes them tolerant to harsh conditions and resistant to antibacterial treatments. Moreover, the biofilms are responsible for causing a broad range of chronic diseases and due to the emergence of antibiotic resistance in bacteria it has really become difficult to treat them with efficacy. Furthermore, the antibiotics available till date are ineffective for treating these biofilm related infections due to their higher values of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), which may result in in-vivo toxicity. Hence, it is critically important to design or screen anti-biofilm molecules that can effectively minimize and eradicate biofilm related infections. In the present article, we have highlighted the mechanism of biofilm formation with reference to different models and various methods used for biofilm detection. A major focus has been put on various anti-biofilm molecules discovered or tested till date which may include herbal active compounds, chelating agents, peptide antibiotics, lantibiotics and synthetic chemical compounds along with their structures, mechanism of action and their respective MICs, MBCs, minimum biofilm inhibitory concentrations (MBICs) as well as the half maximal inhibitory concentration (IC50) values available in the literature so far. Different mode of action of anti biofilm molecules addressed here are inhibition via interference in the quorum sensing pathways, adhesion mechanism, disruption of extracellular DNA, protein, lipopolysaccharides, exopolysaccharides and secondary messengers involved in various signaling pathways. From this study, we conclude that the molecules considered here might be used to treat biofilm-associated infections after significant structural modifications, thereby investigating its effective delivery in the host. It should also be ensured that minimum effective concentration of these molecules must be capable of eradicating biofilm infections with maximum potency without posing any adverse side effects on the host. PMID:28362216
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Babiuk, Lorne A.; Meldrum, Blair; Gupta, V. Sagar; Rouse, Barry T.
1975-01-01
The antiviral activity of 5-methoxymethyl-2′-deoxyuridine (MMUdR) was compared with that of 5-iodo-2′-deoxyuridine (IUdR), cytosine arabinoside (Ara-C), and adenine arabinoside (Ara-A). At concentrations of 2 to 4 μg/ml, MMUdR was inhibitory to herpes simplex virus type 1, but concentrations as high as 128 μg/ml were not inhibitory to three other herpesviruses tested (equine rhinopneumonitis virus, murine cytomegalovirus, and feline rhinopneumonitis virus) or to vaccinia virus. The other nucleosides, in contrast, were inhibitory at similar concentrations (1 to 8 μg/ml) against all viruses tested. The inhibition of HSV-1 by MMUdR appeared to be the result of interference with virus replication rather than the result of drug toxicity to host cells. The drug was not toxic to host cells at 100 times the antiviral concentrations, and pretreatment of host cells with high concentrations of MMUdR had no effect on subsequent virus replication. Combination of MMUdR with either IUdR, Ara-A, or Ara-C gave an enhanced antiviral effect, suggesting that the mechanism of action of MMUdR is different from that of the other three drugs. Antiviral indexes were calculated for each compound and were found to be >250, 80, 40, and 8 for MMUdR, IUdR, Ara-A, and Ara-C, respectively. These were defined as the minimum dose at which toxicity was observed microscopically divided by the dose which reduced plaque numbers by 50%. PMID:1239978
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Brillault, J; Tewes, F; Couet, W; Olivier, J C
2017-01-15
Pulmonary delivery of fluoroquinolones (FQs) is an interesting approach to treat lung infections as it may lead to high local concentrations while minimizing systemic exposure. However, FQs have a rapid diffusion through the lung epithelium giving the pulmonary route no advantage compared to the oral route. Interactions between FQs and metal cations form complexes which limit the diffusion through the epithelial barrier and would reduce the absorption of FQs and maintain high concentrations in the lung. The effects of this complexation depend on the FQ and the metal cations and optimum partners should be selected through in vitro experiments prior to aerosol drug formulation. In this study, CIP was chosen as a representative FQ and 5 cations (Ca 2+ , Mg 2+ , Zn 2+ , Al 3+ , Cu 2+ ) were selected to study the complexation and its effects on permeability, antimicrobial efficacy and cell toxicity. The results showed that the apparent association constants between CIP and cations ranked with the descending order: Cu 2+ >Al 3+ >Zn 2+ >Mg 2+ >Ca 2+ . When a target of 80% complexation was reached with the adequate concentrations of cations, the CIP permeability through the Calu-3 lung epithelial cells was decreased of 50%. Toxicity of the CIP on the Calu-3 cells, with an EC50 evaluated at 7μM, was not significantly affected by the presence of the cations. The minimum inhibitory concentration of CIP for Pseudomonas aeruginosa was not affected or slightly increased in the range of cation concentrations tested, except for Mg 2+ . In conclusion, permeability was the main parameter that was affected by the metal cation complexation while cell toxicity and antimicrobial activity were not or slightly modified. Cu 2+ , with the highest apparent constant of association and with no effect on cell toxicity and antimicrobial activity of the CIP, appeared as a promising cation for the development of a controlled-permeability formulation of CIP for lung treatment. Copyright © 2016 Elsevier B.V. All rights reserved.
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Boogaard, Michael A.; Rivera, Jane E.
2011-01-01
We conducted a series of toxicological treatments with 3-trifluoromethyl-4-nitrophenol (TFM) and a TFM:1% 2′,5-dichloro-4′-nitrosalicylanilide (niclosamide) mixture, two compounds used to control larval sea lamprey (Petromyzon marinus) in Great Lakes tributaries, to evaluate the acute toxicity of the lampricides to a number of nontarget species of concern. Treatments were conducted with yellow stage American eel (Anguilla rostrata), adult and larval haliplid water beetles (Haliplus spp.), a surrogate for the endangered Hungerford’s crawling water beetle (Brychius hungerfordi), and adults of three unionid species—giant floater (Pyganadon grandis), fragile papershell (Leptodea fragilis), and pink heelsplitter (Potamilus alatus). Treatments were conducted using a serial dilution system consisting of nine test concentrations and an untreated control with 20% dilution between concentrations. Narcosis was evident among giant floaters exposed to the TFM and the TFM:1% niclosamide mixture and among pink heelsplitters exposed to the TFM:1% niclosamide mixture only but mostly at concentrations greater than 2-fold that required to kill 100% of larval sea lamprey (minimum lethal concentration (MLC)). Tests with the haliplid beetle suggest the risks to the Hungerford’s crawling water beetle associated with TFM applications are minimal. Concentrations over 2-fold the sea lamprey MLC did not kill adult or larval water beetles. Preliminary behavioral observations suggest water beetles may avoid treatment by crawling out of the water. Adult water beetles exposed to TFM at 3-fold the sea lamprey MLC were observed above the water line more often than controls. The lampricide TFM was not acutely toxic to American eel. Mortalities were rare among American eel exposed to TFM concentrations up to 7-fold the observed sea lamprey MLC. Similarly, for the TFM:1% niclosamide mixture, mortalities were rare among American eel exposed to nearly 5-fold the observed sea lamprey MLC. Overall, acute TFM toxicity was not evident among any of the species examined in this study at concentrations targeted to control larval sea lamprey. Results for the adult unionids should be viewed with caution due to the lack of replication in the treatments.
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Thavamani, Palanisami; Megharaj, Mallavarapu; Naidu, Ravi
2015-06-01
The use of metal-tolerant polyaromatic hydrocarbon (PAH)-degrading bacteria is viable for mitigating metal inhibition of organic compound biodegradation in the remediation of mixed contaminated sites. Many microbial growth media used for toxicity testing contain high concentrations of metal-binding components such as phosphates that can reduce solution-phase metal concentrations thereby underestimate the real toxicity. In this study, we isolated two PAHs-degrading bacterial consortia from long-term mixed contaminated soils. We have developed a new mineral medium by optimising the concentrations of medium components to allow the bacterial growth and at the same time maintain high bioavailable metal (Cd(2+) as a model metal) in the medium. This medium has more than 60 % Cd as Cd(2+) at pH 6.5 as measured by an ion selective electrode and visual MINTEQ model. The Cd-tolerant patterns of the consortia were tested and minimum inhibitory concentration (MIC) derived. The consortium-5 had the highest MIC of 5 mg l(-1) Cd followed by consortium-9. Both cultures were able to completely metabolise 200 mg l(-1) phenanthrene in less than 4 days in the presence of 5 mg l(-1) Cd. The isolated metal-tolerant PAH-degrading bacterial cultures have great potential for bioremediation of mixed contaminated soils.
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Garner, Kendra L; Suh, Sangwon; Keller, Arturo A
2017-05-16
We developed a dynamic multimedia fate and transport model (nanoFate) to predict the time-dependent accumulation of metallic engineered nanomaterials (ENMs) across environmental media. nanoFate considers a wider range of processes and environmental subcompartments than most previous models and considers ENM releases to compartments (e.g., urban, agriculture) in a manner that reflects their different patterns of use and disposal. As an example, we simulated ten years of release of nano CeO 2 , CuO, TiO 2 , and ZnO in the San Francisco Bay area. Results show that even soluble metal oxide ENMs may accumulate as nanoparticles in the environment in sufficient concentrations to exceed the minimum toxic threshold in freshwater and some soils, though this is more likely with high-production ENMs such as TiO 2 and ZnO. Fluctuations in weather and release scenario may lead to circumstances where predicted ENM concentrations approach acute toxic concentrations. The fate of these ENMs is to mostly remain either aggregated or dissolved in agricultural lands receiving biosolids and in freshwater or marine sediments. Comparison to previous studies indicates the importance of some key model aspects including climatic and temporal variations, how ENMs may be released into the environment, and the effect of compartment composition on predicted concentrations.
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Gonçalves, Randys Caldeira; da Silva, Diego Pereira; Signini, Roberta; Naves, Plínio Lázaro Faleiro
2017-12-01
Investigation of the antimicrobial action of carboxymethyl chitosan (CMCh) is among the alternative approaches in the control of pathogenic microorganisms. This study aimed to screen the toxicity using the brine shrimp lethality assay and to investigate the inhibitory activity of carboxymethyl in isolation or in combination with silver nitrate, copper sulfate and zinc sulfate on biofilm formation by Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, Kocuria rhizophila ATCC 9341, Pseudomonas aeruginosa ATCC 9027, Escherichia coli ATCC 25312, and Burkholderia cepacia ATCC 17759. The CMCh was obtained by reacting chitosan with monochloroacetic acid under alkaline conditions, and the occurrence of carboxymethylation was evidenced by FTIR and 1 H NMR spectroscopy. The CMCh was combined with metallic salts (AgNO 3 , CuSO 4 ·5H 2 O and ZnSO 4 ) to perform the bioassays to screen the toxicity, to determine the minimum inhibitory concentration and the impact of sub-inhibitory concentrations against biofilm formation. Although CMCh did not show inhibitory activity against bacterial growth, it had an interesting level of inhibition of bacterial biofilm. The results suggest that sub-inhibitory concentrations of compounds were effective against biofilm formation. Copyright © 2017 Elsevier B.V. All rights reserved.
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Júnior, José G. A. S.; Coutinho, Henrique D. M.; Boris, Ticiana C. C.; Cristo, Janyketchuly S.; Pereira, Nara L. F.; Figueiredo, Fernando G.; Cunha, Francisco A. B.; Aquino, Pedro E. A.; Nascimento, Polyana A. C.; Mesquita, Francisco J. C.; Moreira, Paulo H. F.; Coutinho, Sáskia T. B.; Souza, Ivon T.; Teixeira, Gabriela C.; Ferreira, Najla M. N.; Farina, Eleonora O.; Torres, Cícero M. G.; Holanda, Vanderlan N.; Pereira, Vandbergue S.; Guedes, Maria I. F.
2016-01-01
Introduction: Annona coriacea Mart. (araticum) is a widely distributed tree in the cerrado. Its value is attributed principally to the consumption of its fruit which possesses a large nutritive potential. The objective was to identify the chemical profile and evaluate the antimicrobial and cytoprotective activity of the hydroethanol extract of A. coriacea Mart. (HEAC) leaves against the toxicity of mercury chloride. Materials and Methods: The characterization of components was carried out using high-performance liquid chromatography (HPLC). The minimum inhibitory concentration (MIC) was determined by microdilution method in broth with strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. For evaluation of the modulatory and cytoprotective activity of aminoglycoside antibiotics (gentamicin and amikacin) and mercury chloride (HgCl2), the substances were associated with the HEAC at subinhibitory concentrations (MIC/8). Results and Discussion: The HPLC analysis revealed the presence of flavonoids such as Luteolin (1.84%) and Quercetin (1.19%) in elevated concentrations. The HEAC presented an MIC ≥512 μg/mL and significant antagonistic action in aminoglycosides modulation, and it also showed cytoprotective activity to S. aureus (significance P < 0.0001) and E. coli (significance P < 0.05) bacteria against the mercury chloride heavy metal with significance, this action being attributed to the chelating properties of the flavonoids found in the chemical identification. Conclusions: The results acquired in this study show that the HEAC presents cytoprotective activity over the tested strains in vitro and can also present antagonistic effect when associated with aminoglycosides, reinforcing the necessity of taking caution when combining natural and pharmaceutical products. SUMMARY The hydroalcoholic extract of A. coriacea Mart. presents in vitro cytoprotective activity against the toxic effect of Hg. Abbreviations Used: HPLC-DAD: High-performance liquid chromatography with a diode array detector; MIC: Minimum inhibitory concentration; DMSO: Dimethyl sulfoxide PMID:27695264
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In vitro activity of salicylamide derivatives against vancomycin-resistant enterococci.
Pospisilova, Sarka; Michnova, Hana; Kauerova, Tereza; Pauk, Karel; Kollar, Peter; Vinsova, Jarmila; Imramovsky, Ales; Cizek, Alois; Jampilek, Josef
2018-07-01
A series of 13 salicylamide derivatives was assessed for antibacterial activity against three isolates of vancomycin-resistant Enterococcus faecalis (VRE) and Enterococcus faecalis ATCC 29212 as a quality standard. The minimum inhibitory concentration was determined by the broth microdilution method with subsequent subcultivation of aliquots to assess minimum bactericidal concentration. The growth kinetics was established by the time-kill assay. Ampicillin, ciprofloxacin, tetracycline and vancomycin were used as the reference antibacterial drugs. Three of the investigated compounds showed strong bacteriostatic activity against VRE (0.199-25 µM) comparable to or more potent than ampicillin and ciprofloxacin. In addition, these compounds were tested for synergistic effect with vancomycin, ciprofloxacin and tetracycline, while 5-chloro-2-hydroxy-N-[4-(trifluoromethyl)phenyl]benzamide showed the highest potency as well as synergistic activity with vancomycin against VRE 368. Screening of the cytotoxicity of the most effective compounds was performed using human monocytic leukemia THP-1 cells, and based on LD 50 values, it can be stated that the compounds have insignificant toxicity against human cells. Copyright © 2018 Elsevier Ltd. All rights reserved.
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National review of ambient air toxics observations.
Strum, Madeleine; Scheffe, Richard
2016-02-01
Ambient air observations of hazardous air pollutant (HAPs), also known as air toxics, derived from routine monitoring networks operated by states, local agencies, and tribes (SLTs), are analyzed to characterize national concentrations and risk across the nation for a representative subset of the 187 designated HAPs. Observations from the National Air Toxics Trend Sites (NATTS) network of 27 stations located in most major urban areas of the contiguous United States have provided a consistent record of HAPs that have been identified as posing the greatest risk since 2003 and have also captured similar concentration patterns of nearly 300 sites operated by SLTs. Relatively high concentration volatile organic compounds (VOCs) such as benzene, formaldehyde, and toluene exhibit the highest annual average concentration levels, typically ranging from 1 to 5 µg/m(3). Halogenated (except for methylene chloride) and semivolatile organic compounds (SVOCs) and metals exhibit concentrations typically 2-3 orders of magnitude lower. Formaldehyde is the highest national risk driver based on estimated cancer risk and, nationally, has not exhibited significant changes in concentration, likely associated with the large pool of natural isoprene and formaldehyde emissions. Benzene, toluene, ethylbenzene, and 1,3-butadiene are ubiquitous VOC HAPs with large mobile source contributions that continue to exhibit declining concentrations over the last decade. Common chlorinated organic compounds such as ethylene dichloride and methylene chloride exhibit increasing concentrations. The variety of physical and chemical attributes and measurement technologies across 187 HAPs result in a broad range of method detection limits (MDLs) and cancer risk thresholds that challenge confidence in risk results for low concentration HAPs with MDLs near or greater than risk thresholds. From a national monitoring network perspective, the ability of the HAPs observational database to characterize the multiple pollutant and spatial scale patterns influencing exposure is severely limited and positioned to benefit by leveraging a variety of emerging measurement technologies. Ambient air toxics observation networks have limited ability to characterize the broad suite of hazardous air pollutants (HAPs) that affect exposures across multiple spatial scales. While our networks are best suited to capture major urban-scale signals of ubiquitous volatile organic compound HAPs, incorporation of sensing technologies that address regional and local-scale exposures should be pursued to address major gaps in spatial resolution. Caution should be exercised in interpreting HAPs observations based on data proximity to minimum detection limit and risk thresholds.
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Alnajar, Zahra A Amin; Abdulla, Mahmood A; Ali, Hapipah M; Alshawsh, Mohammed A; Hadi, A Hamid A
2012-03-20
Melastoma malabathricum (MM) is a well-known plant in Malaysian traditional medicine, locally known as senduduk. Its ethanol and aqueous extracts have been used in the present investigation to study the immunomodulatory role on human peripheral blood mononuclear cell (PBMC), and the DPPH, ABTS and FRAP free radical scavenging activities were also measured. Total flavonoids and total phenolic contents were assayed and the antibacterial effect was tested against four species of bacteria; two Gram-positive (Staphylococcus aureus and Streptococcus agalactiae) and two Gram-negative (Escherichia coli and Klebsilla pneumonia). The tests were carried out using the disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. Moreover, the acute toxicity was evaluated in vivo on the ethanol extract of MM to establish its safety when administered orally. In our results, both extracts of MM showed abilities to scavenge DPPH and ABTS free radicals, IC(50) values: (11.599 ± 0.84, 10.573 ± 0.58 µmol/L) and (62.657 ± 0.78, 63.939 ± 0.48 µmol/L) for ethanol and aqueous extracts respectively. Indeed the ethanol extract evidenced high phenolic content (384.33 ± 0.005 mg/g), flavonoids contents (85.8 ± 0.009 mg/g) and ferric reducing antioxidant power (33,590 ± 0.038 mmol/g), with high activity against S. aureus and S. agalactiae (11 ± 0.3 and 12 ± 0.6 mm inhibition zones). Likewise, the percentage of peripheral blood mononuclear cells (PBMC) viability was increased in response to MM, IC(50) values (1.781 ± 1.2 and 6.545 ± 0.93 µg/mL) for ethanol and aqueous extracts, respectively. In addition, our results showed that the MM extract is safe even at a high dose of 5,000 mg/kg and has no oral toxicity. These findings suggest the excellent medicinal bioactivity of MM and explain the popularity of this plant in the folk medicine as a remedy for different illnesses.
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Chelate-assisted phytoextraction of heavy metals in a soil contaminated with a pyritic sludge.
Peñalosa, Jesus Manuel; Carpena, Ramón O; Vázquez, Saúl; Agha, Ramsy; Granado, Ana; Sarro, María José; Esteban, Elvira
2007-05-25
The occurrence of many polluted areas as that affected by the accident of the Aznalcóllar pyrite mine has promoted phytoremediation as a technology able to reduce the risk of heavy metal contamination at low cost. White lupin plant has been considered a good candidate for phytoremediation. We studied the capacity of several complexing agents to improve the ability of white lupin for heavy metal phytoremediation in soils with multi-elemental pollution from acid pyritic sludge. Solution-soil interaction was studied and pot experiments with sludge-affected soil were carried out to this end. The interaction experiments indicated that EDTA and NTA were more efficient than malate and citrate in solubilizing metals (Fe, Mn, Cu, Zn, Cd), with minimum differences between EDTA and NTA. The pot trial showed that NTA was able to mobilize toxic elements from sludge-polluted soil and hence increasing their concentrations in plant (Mn, Cu, Zn, As, Cd). However, the NTA treatment promoted an increase of toxic elements concentrations, especially for As, Cd, Pb, in the lixiviates exceeding the maximum permissible levels, so a careful management of chelate is necessary.
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Capinera, J L; Squitier, J M
2000-06-01
Many photoactive dyes are relatively nontoxic to vertebrates despite their insecticidal properties. Several photoactive dyes known to be toxic to some groups of insects were evaluated at various concentrations for toxicity to American and migratory grasshoppers in laboratory and field studies. Rose bengal and phloxine B were effective at inducing mortality of grasshoppers when applied at 2 and 5% to bran bait, though erythrosin B and uranine were ineffective. Partial replacement of phloxine with uranine in dye mixtures resulted in no significant loss of efficacy. Some indication of feeding inhibition was observed at high dye concentrations, so minimum effective dosages, probably 2%, are optimal. Phloxine B and rose bengal appeared to be stable upon exposure to sunlight, and able to withstand at least 24 h of sunlight without significant degradation. Dyes such as phloxine B could be a viable grasshopper control agent for small or medium-sized grasshopper species because mortality can be induced by consumption of a single flake dusted with 5% dye, and yet pose little hazard to vertebrates. Large species such as American grasshopper must consume several flakes before mortality is induced.
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NASA Astrophysics Data System (ADS)
Ghosh, S.; Ghosh, D.; Bag, P. K.; Bhattacharya, S. C.; Saha, A.
2011-03-01
The present strategy proposes a simple and single step aqueous route for synthesizing stable, fluorescent ZnTe/dendrimer nanocomposites with varying dendrimer terminal groups. In these hybrid materials, the fluorescence of the semiconductor combines with the biomimetic properties of the dendrimer making them suitable for various biomedical applications. The ZnTe nanocomposites thus obtained demonstrate bactericidal activity against enteropathogenic bacteria without having toxic effects on the human erythrocytes. The average size of the ZnTe nanoparticles within the dendrimer matrix was in the range of 2.9-6.0 nm, and they have a good degree of crystallinity with a hexagonal crystal phase. The antibacterial activities of the ZnTe/dendrimer nanocomposites (ZnTe DNCs) as well other semiconductor nanocomposites were evaluated against enteropathogenic bacteria including multi-drug resistant Vibrio cholerae serogroup O1 and enterotoxigenic Escherichia coli (ETEC). ZnTe DNCs had significant antibacterial activity against strains of V. cholerae and ETEC with minimum inhibitory concentrations ranging from 64 to 512 μg ml-1 and minimum bactericidal concentrations ranging from 128 to 1000 μg ml-1. Thus, the observed results suggest that these water-soluble active nanocomposites have potential for the treatment of enteric diseases like diarrhoea and cholera.The present strategy proposes a simple and single step aqueous route for synthesizing stable, fluorescent ZnTe/dendrimer nanocomposites with varying dendrimer terminal groups. In these hybrid materials, the fluorescence of the semiconductor combines with the biomimetic properties of the dendrimer making them suitable for various biomedical applications. The ZnTe nanocomposites thus obtained demonstrate bactericidal activity against enteropathogenic bacteria without having toxic effects on the human erythrocytes. The average size of the ZnTe nanoparticles within the dendrimer matrix was in the range of 2.9-6.0 nm, and they have a good degree of crystallinity with a hexagonal crystal phase. The antibacterial activities of the ZnTe/dendrimer nanocomposites (ZnTe DNCs) as well other semiconductor nanocomposites were evaluated against enteropathogenic bacteria including multi-drug resistant Vibrio cholerae serogroup O1 and enterotoxigenic Escherichia coli (ETEC). ZnTe DNCs had significant antibacterial activity against strains of V. cholerae and ETEC with minimum inhibitory concentrations ranging from 64 to 512 μg ml-1 and minimum bactericidal concentrations ranging from 128 to 1000 μg ml-1. Thus, the observed results suggest that these water-soluble active nanocomposites have potential for the treatment of enteric diseases like diarrhoea and cholera. Electronic supplementary information (ESI) available: Dynamic light scattering, atomic force microscopy and hemolytic activity of the nanocomposites. See DOI: 10.1039/c0nr00610f
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Pasquoto-Stigliani, Tatiane; Campos, Estefânia V R; Oliveira, Jhones L; Silva, Camila M G; Bilesky-José, Natalia; Guilger, Mariana; Troost, Johann; Oliveira, Halley C; Stolf-Moreira, Renata; Fraceto, Leonardo F; de Lima, Renata
2017-07-19
In this study, we prepared, characterized, and performed toxicity analyses of poly(ε-caprolactone) nanocapsules loaded with neem oil. Three formulations were prepared by the emulsion/solvent evaporation method. The nanocapsules showed a mean size distribution around 400 nm, with polydispersity below 0.2 and were stable for 120 days. Cytotoxicity and genotoxicity results showed an increase in toxicity of the oleic acid + neem formulations according to the amount of oleic acid used. The minimum inhibitory concentrations demonstrated that all the formulations containing neem oil were active. The nanocapsules containing neem oil did not affect the soil microbiota during 300 days of exposure compared to the control. Phytotoxicity studies indicated that NC_20 (200 mg of neem oil) did not affect the net photosynthesis and stomatal conductance of maize plants, whereas use of NC_10 (100:100 of neem:oleic acid) and NC_15 (150:50 of neem:oleic acid) led to negative effects on these physiological parameters. Hence, the use of oleic acid as a complement in the nanocapsules was not a good strategy, since the nanocapsules that only contained neem oil showed lower toxicity. These results demonstrate that evaluation of the toxicity of nanopesticides is essential for the development of environmentally friendly formulations intended for applications in agriculture.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
John E. Aston; William A. Apel; Brady D. Lee
2010-12-01
The current study reports the single and combined toxicities of Pb, Zn, and Cu to Acidithiobacillus caldus strain BC13. The observed half-maximal inhibitory concentrations (IC50),?±?95% confidence intervals, for Pb, Zn, and Cu were 0.9?±?0.1?mM, 39?±?0.5?mM, and 120?±?8?mM, respectively. The observed minimum inhibitory concentrations (MIC) for Pb, Zn, and Cu were 7.5?mM, 75?mM, and 250?mM, respectively. When metals were presented in binary mixtures, the toxicities were less than additive. For example, when 50% of the Pb MIC and 50% of the Cu MIC were presented together, the specific growth rate was inhibited by only 59?±?3%, rather than 100%. In addition, themore » presence of ferrous iron in the growth media decreased Pb and Zn toxicity to A. caldus strain BC13. The importance of inoculum history was evaluated by pre-adapting cultures through subsequent transfers in the presence of Pb, Zn, and Cu at their respective IC50s. After pre-adaptation, cultures had specific growth rates 39?±?11, 32?±?7, and 28?±?12% higher in the presence of Pb, Zn, and Cu IC50s, respectively, compared with cultures that had not been pre-adapted. In addition, when cells exposed to the MICs of Pb, Zn, and Cu were harvested, washed, and re-inoculated into fresh, metal-free medium, they grew, showing that the cells remained viable with little residual toxicity. Finally, metal chlorides showed more toxicity than metal sulfates, and studies using sodium chloride or a mixture of metal sulfates and sodium chloride suggested that this was attributable to an additive combination of the metal and chloride toxicities. Environ. Toxicol. Chem. 2010;29:2669–2675. © 2010 SETAC« less
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Aston, John E; Peyton, Brent M; Lee, Brady D; Apel, William A
2010-12-01
The current study reports the single and combined toxicities of Pb, Zn, and Cu to Acidithiobacillus caldus strain BC13. The observed half-maximal inhibitory concentrations (IC50), ± 95% confidence intervals, for Pb, Zn, and Cu were 0.9 ± 0.1 mM, 39 ± 0.5 mM, and 120 ± 8 mM, respectively. The observed minimum inhibitory concentrations (MIC) for Pb, Zn, and Cu were 7.5 mM, 75 mM, and 250 mM, respectively. When metals were presented in binary mixtures, the toxicities were less than additive. For example, when 50% of the Pb MIC and 50% of the Cu MIC were presented together, the specific growth rate was inhibited by only 59 ± 3%, rather than 100%. In addition, the presence of ferrous iron in the growth media decreased Pb and Zn toxicity to A. caldus strain BC13. The importance of inoculum history was evaluated by pre-adapting cultures through subsequent transfers in the presence of Pb, Zn, and Cu at their respective IC50s. After pre-adaptation, cultures had specific growth rates 39 ± 11, 32 ± 7, and 28 ± 12% higher in the presence of Pb, Zn, and Cu IC50s, respectively, compared with cultures that had not been pre-adapted. In addition, when cells exposed to the MICs of Pb, Zn, and Cu were harvested, washed, and re-inoculated into fresh, metal-free medium, they grew, showing that the cells remained viable with little residual toxicity. Finally, metal chlorides showed more toxicity than metal sulfates, and studies using sodium chloride or a mixture of metal sulfates and sodium chloride suggested that this was attributable to an additive combination of the metal and chloride toxicities. Copyright © 2010 SETAC.
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Dwivedy, Abhishek Kumar; Prakash, Bhanu; Chanotiya, Chandan Singh; Bisht, Deepa; Dubey, Nawal Kishore
2017-08-01
The study reports Mentha cardiaca essential oil (EO) as plant based preservative against fungal and aflatoxin contamination of stored dry fruits. Mycoflora analysis of the dry fruits revealed Aspergillus favus LHP-PV-1 as the most aflatoxigenic isolate with highest Aflatoxin B 1 content. M. cardiaca EO showed broad fungitoxic spectrum inhibiting the tested moulds contaminating dry fruits. It's minimum inhibitory concentration (MIC), minimum aflatoxin inhibitory concentration (MAIC) and minimum fungicidal concentration (MFC) against A. favus LHP-PV-1 were recorded to be 1.25, 1.0 and 2.25 µL/mL respectively. The EO caused decrease in ergosterol content and enhanced leakage of Ca 2+ , K + and Mg 2+ ions from treated fungal cells, depicting fungal plasma membrane as the site of antifungal action. The EO showed promising DPPH free radical scavenging activity (IC 50 value:15.89 µL/mL) and favourable safety profile with LD 50 value (7133.70 mg/kg body wt.) when estimated through acute oral toxicity on mice. Carvone (61.62%) was recorded as the major component of the oil during chemical characterisation through GC-MS. Based on strong antifungal, antiaflatoxigenic and antioxidant potential, the chemically characterised M. cardiaca EO may be recommended as safe plant based preservative and shelf life enhancer of food items. This is the first report on antifungal and antiaflatoxigenic activity of M. cardiaca EO. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Trypanocide, cytotoxic, and antifungal activities of Momordica charantia.
Santos, Karla K A; Matias, Edinardo F F; Sobral-Souza, Celestina E; Tintino, Saulo R; Morais-Braga, Maria F B; Guedes, Glaucia M M; Santos, Francisco A V; Sousa, Ana Carla A; Rolón, Miriam; Vega, Celeste; de Arias, Antonieta Rojas; Costa, José G M; Menezes, Irwin R A; Coutinho, Henrique D M
2012-02-01
Chagas disease, caused by Trypanosoma cruzi, is a public health problem. Currently, chemotherapy is the only available treatment for this disease, and the drugs used, nifurtimox and benzonidazol, present high toxicity levels. An alternative for replacing these drugs are natural extracts from Momordica charantia L. (Cucurbitaceae) used in traditional medicine because of their antimicrobial and biological activities. In this study, we evaluated the extract of M. charantia for its antiepimastigote, antifungal, and cytotoxic activities. An ethanol extract of leaves from M. charantia was prepared. To research in vitro antiepimastigote activity, T. cruzi CL-B5 clone was used. Epimastigotes were inoculated at a concentration of 1 × 10(5) cells/mL in 200 µl tryptose-liver infusion. For the cytotoxicity assay, J774 macrophages were used. The antifungal activity was evaluated by microdilution using strains of Candida albicans, Candida tropicalis, and Candida krusei. The effective concentration capable of killing 50% of parasites (IC(50)) was 46.06 µg/mL. The minimum inhibitory concentration (MIC) was ≤ 1024 µg/mL. Metronidazole showed a potentiation of its antifungal effect when combined with an extract of M. charantia. Our results indicate that M. charantia could be a source of plant-derived natural products with antiepimastigote and antifungal-modifying activity with moderate toxicity.
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Heavy-metal resistance in Gram-negative bacteria isolated from Kongsfjord, Arctic.
Neethu, C S; Mujeeb Rahiman, K M; Saramma, A V; Mohamed Hatha, A A
2015-06-01
Isolation and characterization of heterotrophic Gram-negative bacteria was carried out from the sediment and water samples collected from Kongsfjord, Arctic. In this study, the potential of Arctic bacteria to tolerate heavy metals that are of ecological significance to the Arctic (selenium (Se), mercury (Hg), cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) was investigated. Quantitative assay of 130 isolates by means of plate diffusion and tube dilution methods was carried out by incorporation of different concentrations of metals. Growth in Se and Pb at a concentration of 3000 μg/L was significantly lower (P≤0.0001) than at 2000 μg/L. The minimum inhibitory concentration for Cd and Hg was 50 μg/L (P≤0.0001, F=264.23 and P≤0.0001, F=291.08, respectively) even though in the tube dilution test, Hg-containing tubes showed much less growth, revealing its superior toxicity to Cd. Thus, the level of toxicity of heavy metals was found to be in the order of Hg>Cd>Cu>Zn>Pb>Se. Multiple-metal-resistant isolates were investigated for their resistance against antibiotics, and a positive correlation was observed between antibiotic and metal resistance for all the isolates tested. The resistant organisms thus observed might influence the organic and inorganic cycles in the Arctic and affect the ecosystem.
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Roychowdhury, Roopali; Mukherjee, Pritam; Roy, Madhumita
2016-02-01
Eight chromium resistant bacteria were isolated from a dry fly ash sample of DVC-MTPS thermal power plant located in Bankura, West Bengal, India. These isolates displayed different degrees of chromate reduction under aerobic conditions. According to 16S rDNA gene analysis, five of them were Staphylococcus, two were Bacillus and one was Micrococcus. The minimum inhibitory concentration towards chromium and the ability to reduce hexavalent chromium to trivalent chromium was highest in Staphylococcus haemolyticus strain HMR17. All the strains were resistant to multiple heavy metals (As, Cu, Cd, Co, Zn, Mn, Pb and Fe) and reduced toxic hexavalent chromium to relatively non toxic trivalent chromium even in the presence of these multiple heavy metals. All of them showed resistance to different antibiotics. In a soil microcosm study, S. haemolyticus strain HMR17 completely reduced 4 mM hexavalent chromium within 7 days of incubation.
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Oosthuizen, Carel; Arbach, Miriam; Meyer, Debra; Hamilton, Chris; Lall, Namrita
2017-07-01
Mycobacterium tuberculosis remains one of the world's deadliest killers, with an annual death rate of ∼1.5 million. The medicinal effects of garlic have been well documented, and natural products have been shown to have antimycobacterial activity. The current study evaluated the efficacy of six Allium sativum L. polysulfide mixtures as antimycobacterial agents together with their cytotoxic, immunomodulatory, and hepatoprotective activities. The microtitre PrestoBlue assay was used to determine the minimum inhibitory concentrations (MIC). Cytotoxicity was evaluated by using peripheral blood mononuclear cells (PBMC). Excreted cytokine levels were determined by utilizing an enzyme-linked immunosorbent assay (ELISA), by exposing isolated PBMCs to varying concentrations of polysulfide mixtures. Human C3A liver cells were utilized in the hepatoprotective study, to assess the protective effect against the toxicity induced by acetaminophen. Samples with higher amounts of diallyl trisulfide (Sample G4) showed the highest antimycobacterial activity, exhibiting an MIC of 2.5 μg/mL against M. tuberculosis H37Rv. Five samples showed moderate toxicity in PBMC, with G1 showing no toxicity. The selective index of G4 was the highest, with a selectivity index close to one. Two samples, G3 and G6 containing higher amounts of diallyl tetrasulfide and lower amounts of diallyl trisulfide, showed >50% hepatoprotection. This is comparable to a hepatoprotective agent, Silymarin, which showed a hepatoprotective effect of 30% at the tested concentration. Diallyl tetrasulfide showed significant antimycobacterial activity. A combination of higher diallyl tetrasulfide and lower diallyl trisulfide was indicative of hepatoprotective activity.
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Molecular Probes: A Tool for Studying Toxicity of VOCs to P.Putida F1
NASA Astrophysics Data System (ADS)
Singh, R.; Olson, M. S.
2007-12-01
Volatile Organic Compounds (VOCs) are of great concern in ground water remediation, and are generally present in the form of NAPLs in subsurface environments. Among the various treatment technologies, in situ bioremediation is one of the most effective and low-cost treatment options. Many soil bacteria are reported to degrade these organic contaminants via metabolism (using them as a source of carbon to derive energy) or co- metabolism up to certain concentrations. However, larger concentrations of these contaminants are toxic to bacteria. Thus, in order to achieve successful bioremediation, it is important to determine the optimal concentrations of various contaminants that is beneficial for the activity and survival of degrading bacteria. The purpose of this study is to develop a novel method for toxicity analyses of VOC contaminants to the soil bacteria that degrade them. The present study is based on a two-color fluorescence assay of bacterial viability which facilitates actual counting of live and dead bacteria. Pseudomonas putida F1 cells were labeled with a LIVE/DEAD® BacLightTM bacterial viability kit (Invitrogen), which consists of a mixture of two dyes, SYTO 9 and propidium iodide, each with a different ability to penetrate healthy bacterial cells. Live cells stain green whereas propidium iodide (red dye) only penetrates cells with compromised membranes that are considered dead or dying. Stained cells were exposed to different concentrations of trichloroethylene (TCE) and toluene in sealed vials. Change in the concentrations of green and red cells were monitored over the time using fluorescence microscopy. UTHSCSA ImageTool software was used to count the live and dead cells in the images. It was observed that live (green) cell concentrations decreased and dead/damaged (red) cell concentrations increased over time when cells were exposed to TCE. No significant changes were observed in control experiments. Death rate constants calculated based on live cell disappearance and dead/damaged cell appearance were found to be approximately equal for TCE. Results will be presented in terms of dose response and death rate curves. Death rate constants and minimum inhibitory concentrations for survival of P. Putida F1 exposed to TCE and toluene will be compared.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Hodgson, Alfred T.; Shendell, Derek G.; Fisk, William J.
Indoor exposures to toxic and odorous volatile organic compounds (VOCs) are of general concern. Recently, VOCs in portable or relocatable classrooms (RCs) have received particular attention. However, very little was known about indoor environmental quality (IEQ) and the sources, composition, and indoor concentrations of VOCs in RCs. This project task focused on developing and demonstrating a process for selecting interior finish materials for RCs that have relatively low impacts with respect to their emissions of toxic and odorous VOCs. This task was part of a larger project to demonstrate the potential for simultaneous improvements in IEQ and energy efficiency inmore » four new RCs equipped both with a continuously ventilating advanced heating, ventilating, and air conditioning system (HVAC) and a standard HVAC system. These HVACs were operated on alternate weeks. One RC per pair was constructed with standard interior finish materials, and the other included alternate interior materials identified in our prior laboratory study to have low VOC emissions. The RCs were sited in side-by-side pairs at two elementary schools in distinct northern California climate zones. Classroom VOC emission rates (mg hr{sup -1}) and concentrations were predicted based on VOC emission factors ({micro}g m{sup -2} hr{sup -1}) measured for individual materials in the laboratory, the quantities of installed materials and design ventilation rates. Predicted emission rates were compared to values derived from classroom measurements of VOC concentrations and ventilation rates made at pre-occupancy, eight weeks, and 27 weeks. Predicted concentrations were compared to measured integrated VOC indoor minus outdoor concentrations during school hours in the fall cooling season with the advanced HVAC operated. These measured concentrations also were compared between standard and material-modified RCs. Our combined laboratory and field process proved effective by correctly predicting that IEQ impacts of material VOC emissions would be minor when RCs were ventilated at or above code-minimum requirements. Assuming code-minimum ventilation rates are maintained, the benefits attributable to the use of alternate interior finish materials in RC's constructed by the manufacturer associated with this study are small, implying that it is not imperative to use such alternative finishing materials. However, it is essential to avoid materials that can degrade IEQ, and the results of this study demonstrate that laboratory-based material testing combined with modeling and field validation can help to achieve that aim.« less
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Teke, Gerald Ngo; Elisée, Kemadjou Nana; Roger, Kuiate Jules
2013-06-13
The leaves of Cupressus lusitanica Mill. are used in the western highlands of Cameroon for their medicinal property. The leaves of this species were collected in the West Region of Cameroon in August 2010 and subjected to hydrodistillation to obtain the essential oil. The oil was fractionated using adsorption column chromatography. The chemical composition of this oil and its fractions was analysed by gas chromatography-mass spectrometry (GC-MS). The essential oil and fractions were tested for antimicrobial activity against eight bacterial species and six species of Candida by the agar diffusion method. Macrodilution method was used to determine the minimum inhibition concentrations (MICs) and minimum bactericidal and/or fungicidal concentrations (MBCs and MFCs). The toxicity profile of the oil was studied using Swiss mice and Wistar albino rats. Forty-nine compounds were identified in the essential oil. The main components were germacrene D (18.5%), epi-zonarene (8.2%), cis-calamenene (8.2%), terpinen-4-ol (6.3%), linalool (6.0%) and umbellulone (6.0%). Enterococcus faecalis, Proteus mirabilis and Candida albicans were most susceptible to the oil (MICs of 1.25 and 0.16% for bacteria and fungi respectively). The estimated oral LD50 was 6.33 g/kg. There was an increase in sera ALT and AST activities while the blood cells and protein levels decreased in treated animals. The results obtained from this study support the ethnomedicinal use of C. lusitanica leaf oil in the treatment of whooping cough and skin infections though it should be used with care. This plant oil could be useful in the standardisation of phytomedicine.
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Antioxidant and antimicrobial activities of branches extracts of five Juniperus species from Turkey.
Taviano, Maria Fernanda; Marino, Andreana; Trovato, Ada; Bellinghieri, Valentina; La Barbera, Tommaso Massimo; Güvenç, Ayşegül; Hürkul, Muhammed Mesud; Pasquale, Rita De; Miceli, Natalizia
2011-10-01
Several Juniperus species (Cupressaceae) are utilized in folk medicine in the treatment of infections and skin diseases. This work was designed to evaluate the antioxidant and antimicrobial potential of methanol and water branches extracts of Juniperus species from Turkey: Juniperus communis L. var. communis (Jcc), Juniperus communis L. var. saxatilis Pall. (Jcs), Juniperus drupacea Labill. (Jd), Juniperus oxycedrus L. subsp. oxycedrus (Joo), Juniperus oxycedrus L. subsp. macrocarpa (Sibth. & Sm.) Ball. (Jom). Total phenolics, total flavonoids and condensed tannins were spectrophotometrically determined. The antioxidant properties were examined using different in vitro systems. The toxicity was assayed by Artemia salina lethality test. The antimicrobial potential against bacteria and yeasts was evaluated using minimum inhibitory concentration and minimum bactericidal concentration (MIC/MBC) measurements. The effect on bacteria biofilms was tested by microtiter plate assay. Both in the DPPH (1,1-diphenyl-2-picrylhydrazyl) and TBA (thiobarbituric acid) test Jom resulted the most active (IC(50) = 0.034 ± 0.002 mg/mL and 0.287 ± 0.166 µg/mL). Joo exhibited the highest reducing power (1.78 ± 0.04 ASE/mL) and Fe(2+) chelating activity (IC(50) = 0.537 ± 0.006 mg/mL). A positive correlation between primary antioxidant activity and phenolic content was found. The extracts were potentially non-toxic against Artemia salina. They showed the best antimicrobial (MIC = 4.88-30.10 µg/mL) and anti-biofilm activity (60-84%) against S. aureus. The results give a scientific basis to the traditional utilization of these Juniperus species, also demonstrating their potential as sources of natural antioxidant and antimicrobial compounds.
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Grizard, Geneviève; Ouchchane, Lemlih; Roddier, Héléne; Artonne, Christine; Sion, Benoît; Vasson, Marie-Paule; Janny, Laurent
2007-01-01
Due to its extensive production and application, the toxicity of chloracetanilide herbicide alachlor[2-chloro-2',6'-diethyl-N-(methoxymethyl)-acetanilide] should be evaluated to establish minimum effects. In this study, we have examined the in vitro effects of alachlor on human sperm motion using a computer-assisted sperm analyser (CASA). An evaluation of both reactive oxygen species (ROS) and markers of apoptosis was also performed to investigate the mechanism by which alachlor modifies the sperm movement. After exposure up to 2 h to alachlor (0, 0.18, 0.37, 0.90 and 1.85 mM), the percentage of viable, motile spermatozoa and sperm velocities were concentration and/or time dependently decreased. The most sensitive parameters were progressive motility, mean average path velocity and mean straight velocity. Alachlor (1.85 mM) induced an increase in ROS production. A decrease of mitochondrial membrane potential (DeltaPsi(m)), an increase of both phosphatidylserine (PS) externalization and DNA fragmentation, which were concentration and/or time dependent, were also observed. It is possible that toxic effects of alachlor result in an oxidative stress which could act as a mediator of apoptosis. Alachlor could also contribute to some hypofertility cases.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Deville, Curtiland, E-mail: deville@uphs.upenn.ed; Both, Stefan; Hwang, Wei-Ting
2010-11-01
Purpose: To assess whether whole-pelvis (WP) intensity-modulated radiation therapy (IMRT) is associated with increased toxicity compared with prostate-only (PO) IMRT. Methods and Materials: We retrospectively analyzed all patients with prostate cancer undergoing definitive IMRT to 79.2 Gy with concurrent androgen deprivation at our institution from November 2005 to May 2007 with a minimum follow-up of 12 months. Thirty patients received initial WP IMRT to 45 Gy in 1.8-Gy fractions, and thirty patients received PO IMRT. Study patients underwent computed tomography simulation and treatment planning by use of predefined dose constraints. Bladder and rectal dose-volume histograms, maximum genitourinary (GU) and gastrointestinalmore » (GI) Radiation Therapy Oncology Group toxicity grade, and late Grade 2 or greater toxicity-free survival curves were compared between the two groups by use of the Student t test, Fisher exact test, and Kaplan-Meier curve, respectively. Results: Bladder minimum dose, mean dose, median dose, volume receiving 5 Gy, volume receiving 20 Gy, volume receiving 40 Gy, and volume receiving 45 Gy and rectal minimum dose, median dose, and volume receiving 20 Gy were significantly increased in the WP group (all p values < 0.01). Maximum acute GI toxicity was limited to Grade 2 and was significantly increased in the WP group at 50% vs. 13% the PO group (p = 0.006). With a median follow-up of 24 months (range, 12-35 months), there was no difference in late GI toxicity (p = 0.884) or in acute or late GU toxicity. Conclusions: Despite dosimetric differences in the volume of bowel, bladder, and rectum irradiated in the low-dose and median-dose regions, WP IMRT results only in a clinically significant increase in acute GI toxicity, in comparison to PO IMRT, with no difference in GU or late GI toxicity.« less
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Are Vancomycin Trough Concentrations Adequate for Optimal Dosing?
Youn, Gilmer; Jones, Brenda; Jelliffe, Roger W.; Drusano, George L.; Rodvold, Keith A.; Lodise, Thomas P.
2014-01-01
The current vancomycin therapeutic guidelines recommend the use of only trough concentrations to manage the dosing of adults with Staphylococcus aureus infections. Both vancomycin efficacy and toxicity are likely to be related to the area under the plasma concentration-time curve (AUC). We assembled richly sampled vancomycin pharmacokinetic data from three studies comprising 47 adults with various levels of renal function. With Pmetrics, the nonparametric population modeling package for R, we compared AUCs estimated from models derived from trough-only and peak-trough depleted versions of the full data set and characterized the relationship between the vancomycin trough concentration and AUC. The trough-only and peak-trough depleted data sets underestimated the true AUCs compared to the full model by a mean (95% confidence interval) of 23% (11 to 33%; P = 0.0001) and 14% (7 to 19%; P < 0.0001), respectively. In contrast, using the full model as a Bayesian prior with trough-only data allowed 97% (93 to 102%; P = 0.23) accurate AUC estimation. On the basis of 5,000 profiles simulated from the full model, among adults with normal renal function and a therapeutic AUC of ≥400 mg · h/liter for an organism for which the vancomycin MIC is 1 mg/liter, approximately 60% are expected to have a trough concentration below the suggested minimum target of 15 mg/liter for serious infections, which could result in needlessly increased doses and a risk of toxicity. Our data indicate that adjustment of vancomycin doses on the basis of trough concentrations without a Bayesian tool results in poor achievement of maximally safe and effective drug exposures in plasma and that many adults can have an adequate vancomycin AUC with a trough concentration of <15 mg/liter. PMID:24165176
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Chitosan doped with nanoparticles of copper, nickel and cobalt.
Cárdenas-Triviño, Galo; Elgueta, Carolina; Vergara, Luis; Ojeda, Javier; Valenzuela, Ariel; Cruzat, Christian
2017-11-01
Metal colloids in 2 propanol using nanoparticles (NPs) of copper, nickel and cobalt were prepared by Chemical Liquid Deposition (CLD) method. The resulting colloidal dispersions were characterized by Transmission Electron Microscopy (TEM). The colloids were supported in chitosan. Then, microbiological assays were performed using E. coli and S. aureus in order to determine the bactericide/bacteriostatic activity of nanoparticles (NPs) trapped or chelated with chitosan. Finally, the toxicity of the metal colloids Cu, Ni and Co was tested. Bio-assays were conducted in three different animal species. First of all on earth warms (Eisenia foetida) to evaluate the toxicity and the biocompatibility of chitosan in lactic acid (1% and 0.5%). Secondly bio-assay done in fishes (rainbow trout), the liver toxicity of NPs in vivo was evaluated. Finally, a bio-assay was conducted in Sprange-Dawley rats of 100g weight, which were injected intraperitoneally with different solutions of chitosan metal colloids. Then, the minimum and maximum concentration were determined for copper, nickel and cobalt. The purpose of the use of chitosan was acting as a carrier for some magnetic NPs, which toxicity would allow to obtain new polymeric materials with potential applications as magnet future drugs carrier. Copyright © 2017 Elsevier B.V. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Chen, Yuhchyau; Pandya, Kishan J.; Feins, Richard
Purpose: We report the toxicity profile and pharmacokinetic data of a schedule-dependent chemoradiation regimen using pulsed low-dose paclitaxel for radiosensitization in a Phase I study for inoperable non-small-cell lung cancer. Methods and Materials: Paclitaxel at escalating doses of 15 mg/m{sup 2}, 20 mg/m{sup 2}, and 25 mg/m{sup 2} were infused on Monday, Wednesday, and Friday with daily chest radiation in cohorts of 6 patients. Daily radiation was delayed for maximal G2/M arrest and apoptotic effect, an observation from preclinical investigations. Plasma paclitaxel concentration was determined by high-performance liquid chromatography. Results: Dose-limiting toxicities included 3 of 18 patients with Grade 3more » pneumonitis and 3 of 18 patients with Grade 3 esophagitis. There was no Grade 4 or 5 pneumonitis or esophagitis. There was also no Grade 3 or 4 neutropenia, thrombocytopenia, anemia or neuropathy. For Dose Levels I (15 mg/m{sup 2}), II (20 mg/m{sup 2}), and III (25 mg/m{sup 2}), the mean peak plasma level was 0.23 {+-} 0.06 {mu}mol/l, 0.32 {+-} 0.05 {mu}mol/l, and 0.52 {+-} 0.14 {mu}mol/l, respectively; AUC was 0.44 {+-} 0.09 {mu}mol/l, 0.61 {+-} 0.1 {mu}mol/l, and 0.96 {+-} 0.23 {mu}mol/l, respectively; and duration of drug concentration >0.05 {mu}mol/l (t > 0.05 {mu}mol/l) was 1.6 {+-} 0.3 h, 1.9 {+-} 0.2 h, and 3.0 {+-} 0.9 h, respectively. Conclusion: Pulsed low-dose paclitaxel chemoradiation is associated with low toxicity. Pharmacokinetic data showed that plasma paclitaxel concentration >0.05 {mu}mol/l for a minimum of 1.6 h was sufficient for effective radiosensitization.« less
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Contamination of the O2 soil horizon by zinc smelting and its effect on woodlouse survival
Beyer, W.N.; Miller, G.W.; Cromartie, E.J.
1984-01-01
Samples of litter from the 02 horizon of Dekalb soil (loamyskeletal, mixed, mesic Typic Dystrochrept) were collected from 18 ridgetop sites on a transect that ran by two Zn smelters in Palmerton, Pa. Metal concentrations increased by regular gradations from a minimum at a site 105 km west of the smelters (67 mg/kg Zn, 0.85 mg/kg Cd, 150 mg/kg Pb, 11 mg/kg Cu) to a maximum 1.2 km east of the smelters (35,000 mg/kg Zn, 1300 mg/kg Cd, 3200 mg/kg Pb, 280 mg/kg Cu), and then decreased until they reached an eastern minimum at the easternmost site, 19 km from the smelters. An increase in the P concentrations near the smelters showed that the emissions were disrupting nutrient flow through the ecosystem. An increase in the pH near the smelters was attributed to the high concentrations of Zn. The log of the distance of the sites from the smelters was significantly correlated (r = - 0.80, p < 0.05) with the mortality of woodlice (Porcellio scaber Latreille} fed samples of the litter during an 8-week test. There was substantial mortality of woodlice observed even in the 02 litter collected 19 km east of the smelters. Zinc, cadmium, lead, copper, and sulfur were experimentally added, alone or in combination, to 02 litter collected far from any known source of metal emissions. The highest concentration of Zn added (20,000 mg/kg) was toxic enough to account for the mortality observed in the earlier test. A lower concentration of Zn (5000 mg/kg) as well as the concentration of Cd (500 mg/kg) tested also significantly (p < 0.05) increased the mortality of woodlice.
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Cartagena, Andrés Felipe; Esmerino, Luís Antonio; Polak-Junior, Rogerio; Olivieri Parreiras, Sibelli; Domingos Michél, Milton; Farago, Paulo Vitor; Campanha, Nara Hellen
2017-02-01
The purpose of this study was to develop a new oral drug delivery system by incorporating polymeric miconazole nitrate (MN) microparticles on an experimental antifungal denture adhesive (DA). Spray drying Eudragit L-100 (E) and Gantrez MS-955 (G) MN-microparticles were incorporated in DA. DAE1, DAG1, DAEG1, DAE2, DAG2, DAEG2 groups were obtained from the combination of polymers used in MN-microparticles (E, G and EG) and concentration of MN into DA (1, for 1% and 2, for 2%). DA with 2% pure MN (DAM) and DA without microparticles or drug (DACT) were both control groups. All groups were evaluated to determine microbiological assay, adhesive force and toxicity. Minimum inhibitory concentration (MIC) against Candida albicans was performed by broth micro-dilution and agar dilution methods in extract of DAs and conventional gel form (Daktarin ® ). Adhesive load testing was made between acrylic resin samples on a universal testing machine after immersion in water. The toxicity of several dilutions of DAs was performed with Artemia salina bioassay after 24 and 48h. Data of adhesive force were evaluated with two-way ANOVA and Bonferroni tests (α=0.05). The concentration required to kill 50% (LC50) was determined using the Provit analysis. DA with polymeric microparticles and pure drug presented MIC between 1.25-5μg/mL similar to MIC values of DAM. DAEG2, DAEG1, DAG20 showed the most actives against C. albicans. The best adhesive properties were exhibited by DAEG2, consisting of high initial adhesive force which was maintained for up to 6h. The extracts of all DA presented low or not toxicity at 24 and 48h. DA containing 2% of MN loaded in microparticles made by Gantrez MS-955 alone or combined with Eudragit L-100 produce effective antifungal activity, good adhesive force, and no toxicity effect being a promising therapeutics for removable denture wearers affected by denture stomatitis. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
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Sowmya, M; Rejula, M P; Rejith, P G; Mohan, Mahesh; Karuppiah, Makesh; Hatha, A A Mohamed
2014-07-01
Microorganisms which can resist high concentration of toxic heavy metals are often considered as effective tools of bioremediation from such pollutants. In the present study, sediment samples from Vembanad Lake were screened for the presence of halophilic bacteria that are tolerant to heavy metals. A total of 35 bacterial strains belonging to different genera such as Alcaligenes, Vibrio, Kurthia, Staphylococcus and members of the family Enterobacteriaceae were isolated from 21 sediment samples during February to April, 2008. The salt tolerance and optimum salt concentrations of the isolates revealed that most of them were moderate halophiles followed by halotolerant and extremely halotolerant groups. The minimum inhibitory concentrations (MICs) against cadmium and lead for each isolate revealed that the isolates showed higher MIC against lead than cadmium. Based on the resistance limit concentration, most of them were more tolerant to lead than cadmium at all the three salt concentrations tested. Heavy metal removal efficiency of selected isolates showed a maximum reduction of 37 and 99% against cadmium and lead respectively. The study reveals the future prospects of halophilic microorganisms in the field of bioremediation.
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Valle, Demetrio L.; Cabrera, Esperanza C.; Puzon, Juliana Janet M.; Rivera, Windell L.
2016-01-01
Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria. PMID:26741962
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Valle, Demetrio L; Cabrera, Esperanza C; Puzon, Juliana Janet M; Rivera, Windell L
2016-01-01
Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria.
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Rafiq, Muhammad Tariq; He, Zhenli; Sun, Kewang; Xiaoe, Yang
2015-01-01
The minimum concentration of cadmium (Cd), by Chinese cabbage grown on Cd contaminated soils that can initiate toxicity in human liver cells using in vitro digestion coupled with Caco-2/HL-7702 cell models was studied. Cadmium bioaccessibility in the gastric phase for yellow soil (YS) cabbage (40.84%) and calcareous soil (CS) cabbage (21.54%) was significantly higher than small intestinal phase with the corresponding values of 21.2% and 11.11%, respectively. Cadmium bioavailability was higher in YS cabbage (5.27%–14.66%) than in CS cabbage (1.12%–9.64%). Cadmium concentrations (>0.74 μg) transported from YS and CS cabbage were able to induce oxidative (MDA, H2O2) stress by inhibiting antioxidant (SOD, GPx) enzyme activities in human liver cells (HL-7702). Additionally the study revealed that the ingestion of Cd contaminated Chinese cabbage grown in acidic soil (yellow soil) weakened the antioxidant defense system under all levels of contamination (2, 6, and 9 mg·kg−1) which ultimately escalated the oxidative stress in liver cells; however, in case of CS cabbage, a marked oxidative stress was observed only at 9 mg kg−1 Cd level of soil. Therefore, it is necessary to monitor Cd concentrations in leafy vegetables grown on acidic soils to minimize human health risk. PMID:26167479
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Zhang, Liangmao; Wei, Caidi; Zhang, Hui; Song, Mingwei
2017-10-01
The typical environmental endocrine disruptor nonylphenol is becoming an increasingly common pollutant in both fresh and salt water; it compromises the growth and development of many aquatic organisms. As yet, water quality criteria with respect to nonylphenol pollution have not been established in China. Here, the predicted "no effect concentration" of nonylphenol was derived from an analysis of species sensitivity distribution covering a range of species mainly native to China, as a means of quantifying the ecological risk of nonylphenol in surface fresh water. The resulting model, based on the log-logistic distribution, proved to be robust; the minimum sample sizes required for generating a stable estimate of HC 5 were 12 for acute toxicity and 13 for chronic toxicity. The criteria maximum concentration and criteria continuous concentration were, respectively 18.49 μg L -1 and 1.85 μg L -1 . Among the 24 sites surveyed, two were associated with a high ecological risk (risk quotient >1) and 12 with a moderate ecological risk (risk quotient >0.1). The potentially affected fraction ranged from 0.008% to 24.600%. The analysis provides a theoretical basis for both short- and long-term risk assessments with respect to nonylphenol, and also a means to quantify the risk to aquatic ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Calculating background levels for ecological risk parameters in toxic harbor sediment
Leadon, C.J.; McDonnell, T.R.; Lear, J.; Barclift, D.
2007-01-01
Establishing background levels for biological parameters is necessary in assessing the ecological risks from harbor sediment contaminated with toxic chemicals. For chemicals in sediment, the term contaminated is defined as having concentrations above background and significant human health or ecological risk levels. For biological parameters, a site could be considered contaminated if levels of the parameter are either more or less than the background level, depending on the specific parameter. Biological parameters can include tissue chemical concentrations in ecological receptors, bioassay responses, bioaccumulation levels, and benthic community metrics. Chemical parameters can include sediment concentrations of a variety of potentially toxic chemicals. Indirectly, contaminated harbor sediment can impact shellfish, fish, birds, and marine mammals, and human populations. This paper summarizes the methods used to define background levels for chemical and biological parameters from a survey of ecological risk investigations of marine harbor sediment at California Navy bases. Background levels for regional biological indices used to quantify ecological risks for benthic communities are also described. Generally, background stations are positioned in relatively clean areas exhibiting the same physical and general chemical characteristics as nearby areas with contaminated harbor sediment. The number of background stations and the number of sample replicates per background station depend on the statistical design of the sediment ecological risk investigation, developed through the data quality objective (DQO) process. Biological data from the background stations can be compared to data from a contaminated site by using minimum or maximum background levels or comparative statistics. In Navy ecological risk assessments (ERA's), calculated background levels and appropriate ecological risk screening criteria are used to identify sampling stations and sites with contaminated sediments.
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Zhang, Rong; Saito, Ryuta; Mano, Yui; Kanamori, Masayuki; Sonoda, Yukihiko; Kumabe, Toshihiro; Tominaga, Teiji
2014-01-30
Convection-enhanced delivery (CED) has been developed as a potentially effective drug-delivery strategy into the central nervous system. In contrast to systemic intravenous administration, local delivery achieves high concentration and prolonged retention in the local tissue, with increased chance of local toxicity, especially with toxic agents such as chemotherapeutic agents. Therefore, the factors that affect local toxicity should be extensively studied. With the assumption that concentration-oriented evaluation of toxicity is important for local CED, we evaluated the appearance of local toxicity among different agents after delivery with CED and studied if it is dose dependent or concentration dependent. Local toxicity profile of chemotherapeutic agents delivered via CED indicates BCNU was dose-dependent, whereas that of ACNU was concentration-dependent. On the other hand, local toxicity for doxorubicin, which is not distributed effectively by CED, was dose-dependent. Local toxicity for PLD, which is extensively distributed by CED, was concentration-dependent. Traditional evaluation of drug induced toxicity was dose-oriented. This is true for systemic intravascular delivery. However, with local CED, toxicity of several drugs exacerbated in concentration-dependent manner. From our study, local toxicity of drugs that are likely to distribute effectively tended to be concentration-dependent. Concentration rather than dose may be more important for the toxicity of agents that are effectively distributed by CED. Concentration-oriented evaluation of toxicity is more important for CED. Copyright © 2013 Elsevier B.V. All rights reserved.
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Leite, João Jaime Giffoni; Brito, Erika Helena Salles; Cordeiro, Rossana Aguiar; Brilhante, Raimunda Sâmia Nogueira; Sidrim, José Júlio Costa; Bertini, Luciana Medeiros; Morais, Selene Maia de; Rocha, Marcos Fábio Gadelha
2009-01-01
The present study had the aim of testing the hexane and methanol extracts of avocado seeds, in order to determine their toxicity towards Artemia salina, evaluate their larvicidal activity towards Aedes aegypti and investigate their in vitro antifungal potential against strains of Candida spp, Cryptococcus neoformans and Malassezia pachydermatis through the microdilution technique. In toxicity tests on Artemia salina, the hexane and methanol extracts from avocado seeds showed LC50 values of 2.37 and 24.13 mg mL-1 respectively. Against Aedes aegypti larvae, the LC50 results obtained were 16.7 mg mL-1 for hexane extract and 8.87 mg mL-1 for methanol extract from avocado seeds. The extracts tested were also active against all the yeast strains tested in vitro, with differing results such that the minimum inhibitory concentration of the hexane extract ranged from 0.625 to 1.25mg L-(1), from 0.312 to 0.625 mg mL-1 and from 0.031 to 0.625 mg mL-1, for the strains of Candida spp, Cryptococcus neoformans and Malassezia pachydermatis, respectively. The minimal inhibitory concentration for the methanol extract ranged from 0.125 to 0.625 mg mL-1, from 0.08 to 0.156 mg mL-1 and from 0.312 to 0.625 mg mL-1, for the strains of Candida spp., Cryptococcus neoformans and Malassezia pachydermatis, respectively.
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de Sa, Nivea Pereira; Possa, Ana Paula; Perez, Pilar; Ferreira, Jaqueline Maria Siqueira; Fonseca, Nayara Cristina; Lino, Cleudiomar Inacio; Cruz, Lana Barreto; de Oliveira, Renata Barbosa; Rosa, Carlos Augusto; Borelli, Beatriz Martins; Mylonakis, Eleftherios; Fuchs, Beth Burgwyn; Johann, Susana
2018-05-30
Background The increasing incidence of invasive forms of candidiasis and resistance to antifungal therapy leads us to seek new and more effective antifungal compounds. Objectives Investigate the antifungal activity and toxicity as well as to evaluate the potential targets of 2-cyclohexylidenhydrazo-4-phenyl-thiazole (CPT) in Candida albicans. Methods The antifungal activity of CPT against the survival of C. albicans was investigated in Caenorhabditis elegans. Additionally, we determined the effect of CPT on the inhibition of C. albicans adhesion capacity to buccal epithelial cells (BECs), the toxicity of CPT in mammalian cells, and the potential targets of CPT in C. albicans. Results CPT exhibited a minimum inhibitory concentration (MIC) value of 0.4-1.9 µg/mL. Furthermore, CPT at high concentrations (>60 x MIC) showed no or low toxicity in HepG2 cells and <1% haemolysis in human erythrocytes. In addition, CPT decreased the adhesion capacity of yeasts to the BECs and prolonged the survival of C. elegans infected with C. albicans. Analysis of CPT-treated the cells showed that their cell wall was thinner than that of untreated cells, especially the glucan layer. We found that there was a significantly lower quantity of 1,3-β-D-glucan present in CPT-treated cells than that in untreated cells. Assays performed on several mutant strains showed that the MIC value of CPT was high for its antifungal activity on yeasts with defective 1,3-β-glucan synthase. Conclusions In conclusion, CPT appears to target the cell wall of C. albicans, exhibits low toxicity in mammalian cells, and prolongs the survival of C. elegans infected with C. albicans. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.
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Watanabe, Haruna; Tamura, Ikumi; Abe, Ryoko; Takanobu, Hitomi; Nakamura, Ataru; Suzuki, Toshinari; Hirose, Akihiko; Nishimura, Tetsuji; Tatarazako, Norihisa
2016-04-01
Principles of concentration addition and independent action have been used as effective tools to predict mixture toxicity based on individual component toxicity. The authors investigated the toxicity of a pharmaceutical mixture composed of the top 10 detected active pharmaceutical ingredients (APIs) in the Tama River (Tokyo, Japan) in a relevant concentration ratio. Both individual and mixture toxicities of the 10 APIs were evaluated by 3 short-term chronic toxicity tests using the alga Pseudokirchneriella subcapitata, the daphnid Ceriodaphnia dubia, and the zebrafish Danio rerio. With the exception of clarithromycin toxicity to alga, the no-observed-effect concentration of individual APIs for each test species was dramatically higher than the highest concentration of APIs found in the environment. The mixture of 10 APIs resulted in toxicity to alga, daphnid, and fish at 6.25 times, 100 times, and 15,000 times higher concentrations, respectively, than the environmental concentrations of individual APIs. Predictions by concentration addition and independent action were nearly identical for alga, as clarithromycin was the predominant toxicant in the mixture. Both predictions described the observed mixture toxicity to alga fairly well, whereas they slightly underestimated the observed mixture toxicity in the daphnid test. In the fish embryo test, the observed toxicity fell between the predicted toxicity by concentration addition and independent action. These results suggested that the toxicity of environmentally relevant pharmaceutical mixtures could be predicted by individual toxicity using either concentration addition or independent action. © 2015 SETAC.
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Sales, Débora Lima; Morais-Braga, Maria Flaviana Bezerra; Santos, Antonia Thassya Lucas Dos; Machado, Antonio Judson Targino; Araujo Filho, João Antonio de; Dias, Diógenes de Queiroz; Cunha, Francisco Assis Bezerra da; Saraiva, Rogério de Aquino; Menezes, Irwin Rose Alencar de; Coutinho, Henrique Douglas Melo; Costa, José Galberto Martins; Ferreira, Felipe Silva; Alves, Rômulo Romeu da Nóbrega; Almeida, Waltécio de Oliveira
2017-08-01
The increase in microorganisms with resistance to medications has caused a strong preoccupation within the medical and scientific community. Animal toxins studies, such as parotoid glandular secretions from amphibians, possesses a great potential in the development of drugs, such as antimicrobials, as these possess bioactive compounds. It was evaluated Rhinella jimi (Stevaux, 2002) glandular secretions against standard and multi-resistant bacterial strains; the effect of secretions combined with drugs; and determined the toxicity using two biologic in vivo models, and a in vitro model with mice livers. Standard strains were used for the determination of the Minimum Inhibitory Concentration (MIC), while for the modulatory activity of antibiotics, the clinical isolates Escherichia coli 06, Pseudomonas aeruginosa 03 and Staphylococcus aureus 10 were used. Modulatory activity was evaluated by the broth microdilution method with aminoglycosides and β-lactams as target antibiotics. The secretions in association with the antibiotics have a significant reduction in MIC, both the aminoglycosides and β-lactams. The toxicity and cytotoxicity results were lower than the values used in the modulation. R. jimi glandular secretions demonstrated clinically relevant results regarding the modulation of the tested antimicrobials. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
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Antifungal activity of essential oils of Croton species from the Brazilian Caatinga biome.
Fontenelle, R O S; Morais, S M; Brito, E H S; Brilhante, R S N; Cordeiro, R A; Nascimento, N R F; Kerntopf, M R; Sidrim, J J C; Rocha, M F G
2008-05-01
To find new antifungal agents among essential oils from Brazilian Croton species. Plant leaves were steam distilled and the obtained essential oils were analyzed by gas chromatography/mass spectroscopy. The main constituents were estragole and anethole for Croton zehntneri, methyl-eugenol and bicyclogermacrene for Croton nepetaefolius and spathulenol and bicyclogermacrene for Croton argyrophylloides. The antifungal activity of essential oils was evaluated against Candida albicans, Candida tropicalis and Microsporum canis by the agar-well diffusion method and the minimum inhibitory concentration (MIC) by the broth microdilution method. Essential oils of Croton species demonstrated better activity against M. canis. Among the three plants C. argyrophylloides showed the best results, with MIC ranging from 9 to 19 microg ml(-1). The acute administration of the essential oil up to 3 g kg(-1) by the oral route to mice was devoid of overt toxicity. The studied essential oils are active in vitro against the dermatophyte M. canis and present relative lack of acute toxicity in vivo. Because of its antifungal activity and low toxicity, the essential oils of studied Croton species are promising sources for new phytotherapeutic agents to treat dermatophytosis.
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Genetic toxicity of dillapiol and spinosad larvicides in somatic cells of Drosophila melanogaster.
Aciole, Eliezer H Pires; Guimarães, Nilza N; Silva, Andre S; Amorim, Erima M; Nunomura, Sergio M; Garcia, Ana Cristina L; Cunha, Kênya S; Rohde, Claudia
2014-04-01
Higher rates of diseases transmitted from insects to humans led to the increased use of organophosphate insecticides, proven to be harmful to human health and the environment. New, more effective chemical formulations with minimum genetic toxicity effects have become the object of intense research. These formulations include larvicides derived from plant extracts such as dillapiol, a phenylpropanoid extracted from Piper aduncum, and from microorganisms such as spinosad, formed by spinosyns A and D derived from the Saccharopolyspora spinosa fermentation process. This study investigated the genotoxicity of dillapiol and spinosad, characterising and quantifying mutation events and chromosomal and/or mitotic recombination using the somatic mutation and recombination test (SMART) in wings of Drosophila melanogaster. Standard cross larvae (72 days old) were treated with different dillapiol and spinosad concentrations. Both compounds presented positive genetic toxicity, mainly as mitotic recombination events. Distilled water and doxorubicin were used as negative and positive controls respectively. Spinosad was 14 times more genotoxic than dillapiol, and the effect was found to be purely recombinogenic. However, more studies on the potential risks of insecticides such as spinosad and dillapiol are necessary, based on other experimental models and methodologies, to ensure safe use. © 2013 Society of Chemical Industry.
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NASA Astrophysics Data System (ADS)
Retnakumari, Archana; Setua, Sonali; Menon, Deepthy; Ravindran, Prasanth; Muhammed, Habeeb; Pradeep, Thalappil; Nair, Shantikumar; Koyakutty, Manzoor
2010-02-01
Molecular-receptor-targeted imaging of folate receptor positive oral carcinoma cells using folic-acid-conjugated fluorescent Au25 nanoclusters (Au NCs) is reported. Highly fluorescent Au25 clusters were synthesized by controlled reduction of Au+ ions, stabilized in bovine serum albumin (BSA), using a green-chemical reducing agent, ascorbic acid (vitamin-C). For targeted-imaging-based detection of cancer cells, the clusters were conjugated with folic acid (FA) through amide linkage with the BSA shell. The bioconjugated clusters show excellent stability over a wide range of pH from 4 to 14 and fluorescence efficiency of ~5.7% at pH 7.4 in phosphate buffer saline (PBS), indicating effective protection of nanoclusters by serum albumin during the bioconjugation reaction and cell-cluster interaction. The nanoclusters were characterized for their physico-chemical properties, toxicity and cancer targeting efficacy in vitro. X-ray photoelectron spectroscopy (XPS) suggests binding energies correlating to metal Au 4f7/2~83.97 eV and Au 4f5/2~87.768 eV. Transmission electron microscopy and atomic force microscopy revealed the formation of individual nanoclusters of size ~1 nm and protein cluster aggregates of size ~8 nm. Photoluminescence studies show bright fluorescence with peak maximum at ~674 nm with the spectral profile covering the near-infrared (NIR) region, making it possible to image clusters at the 700-800 nm emission window where the tissue absorption of light is minimum. The cell viability and reactive oxygen toxicity studies indicate the non-toxic nature of the Au clusters up to relatively higher concentrations of 500 µg ml-1. Receptor-targeted cancer detection using Au clusters is demonstrated on FR+ve oral squamous cell carcinoma (KB) and breast adenocarcinoma cell MCF-7, where the FA-conjugated Au25 clusters were found internalized in significantly higher concentrations compared to the negative control cell lines. This study demonstrates the potential of using non-toxic fluorescent Au nanoclusters for the targeted imaging of cancer.
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Pérez-Alvarez, Itzayana; Islas-Flores, Hariz; Gómez-Oliván, Leobardo Manuel; Barceló, Damià; López De Alda, Miren; Pérez Solsona, Sandra; Sánchez-Aceves, Livier; SanJuan-Reyes, Nely; Galar-Martínez, Marcela
2018-05-08
Due to the activities inherent to medical care units, the hospital effluent released contains diverse contaminants such as tensoactives, disinfectants, metals, pharmaceutical products and chemical reagents, which are potentially toxic to the environment since they receive no treatment or are not effectively removed by such treatment before entering the drain. They are incorporated into municipal wastewater, eventually entering water bodies where they can have harmful effects on organisms and can result in ecological damage. To determine the toxicological risk induced by this type of eflluents, eight metals and 11 pharmaceuticals were quantified, in effluent from a hospital. Developmental effects, teratogenesis and oxidative stress induction were evaluated in two bioindicator species: Xenopus laevis and Lithobates catesbeianus. FETAX (frog embryo teratogenesis assay-Xenopus) was used to obtain the median lethal concentration (LC 50 ), effective concentration inducing 50% malformation (EC 50 ), teratogenic index (TI), minimum concentration to inhibit growth (MCIG), and the types of malformation induced. Twenty oocytes in midblastula transition were exposed to six concentrations of effluent (0.1, 0.3, 0.5, 0.7, 0.9, 1%) and negative and positive (6-aminonicotinamide) controls. After 96 h of exposure, diverse biomarkers of oxidative damage were evaluated: hydroperoxide content, lipid peroxidation, protein carbonyl content, and the antioxidant enzymes superoxide dismutase and catalase. TI was 3.8 in X. laevis and 4.0 in L. catesbeianus, both exceed the value in the FETAX protocol (1.2), indicating that this effluent is teratogenic to both species. Growth inhibition was induced as well as diverse malformation including microcephaly, cardiac and facial edema, eye malformations, and notochord, tail, fin and gut damage. Significant differences relative to the control group were observed in both species with all biomarkers. This hospital effluent contains contaminants which represents a toxic risk, since these substances are teratogenic to the bioindicators used. The mechanism of damage induction may be associated with oxidative stress. Copyright © 2018 Elsevier Ltd. All rights reserved.
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Toxic metals in cigarettes and human health risk assessment associated with inhalation exposure.
Benson, Nsikak U; Anake, Winifred U; Adedapo, Adebusayo E; Fred-Ahmadu, Omowunmi H; Ayejuyo, Olusegun O
2017-11-08
This study evaluated the concentrations of cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), and zinc (Zn) in 10 branded cigarettes commonly consumed in Nigeria. Chemical sequential extraction method and pseudo-total metal digestion procedure were used for extraction of metals from filler tobacco and filter samples. Samples were analyzed using flame atomic absorption spectrometry (FAAS). The filler tobacco of cigarettes had Cd, Cu, Fe, Mn, Pb, and Zn concentrations in the ranges of 5.90-7.94, 18.26-34.94, 192.61-3494.05, 44.67-297.69, 17.21-74.78, and 47.02-167.31 μg/cigarette, respectively. The minimum and maximum concentrations in the filter samples were 8.67-12.34 μg/g of Cd, 1.77-36.48 μg/g of Cu, 1.83-15.27 μg/g of Fe, 3.82-7.44 μg/g of Mn, 4.09-13.78 μg/g of Pb, and 30.07-46.70 μg/g of Zn. The results of this study showed that the concentrations of heavy metals in the filler tobacco samples were consistently higher than those obtained for the cigarette filters except for Cd. Toxic metals were largely found in the most labile chemical fractions. Moderate to very high risks are found associated with potential exposure to Cd and Pb. The carcinogenic risks posed by Cd and Pb ranged between 1.87E-02 and 2.52E-02, 1.05E-03 and 4.76E-03, respectively, while the non-carcinogenic risk estimates for Cd and Pb were greater than 1.0 (HI > 1). Toxic metals in cigarette may have significant carcinogenic and non-carcinogenic health effects associated with inhalation exposure. Continuous monitoring and regulations of the ingredients of imported and locally produced tobacco products are advocated.
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Influence of Scaffold Size on Bactericidal Activity of Nitric Oxide Releasing Silica Nanoparticles
Carpenter, Alexis W.; Slomberg, Danielle L.; Rao, Kavitha S.; Schoenfisch, Mark H.
2011-01-01
A reverse microemulsion synthesis was used to prepare amine functionalized silica nanoparticles of three distinct sizes (i.e., 50, 100, and 200 nm) with identical amine concentrations. The resulting hybrid nanoparticles, consisting of N-(6 aminohexyl) aminopropyltrimethoxysilane and tetraethoxysilane, were highly monodisperse in size. N-diazeniumdiolate nitric oxide (NO) donors were subsequently formed on secondary amines while controlling reaction conditions to keep the total amount of nitric oxide (NO) released constant for each particle size. The bactericidal efficacy of the NO releasing nanoparticles against Pseudomonas aeruginosa increased with decreasing particle size. Additionally, smaller diameter nanoparticles were found to associate with the bacteria at a faster rate and to a greater extent than larger particles. Neither control (non-NO-releasing) nor NO releasing particles exhibited toxicity towards L929 mouse fibroblasts at concentrations above their respective minimum bactericidal concentrations. This study represents the first investigation of the bactericidal efficacy of NO-releasing silica nanoparticles as a function of particle size. PMID:21842899
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Efficacy and Safety of Leucine Supplementation in the Elderly.
Borack, Michael S; Volpi, Elena
2016-12-01
Leucine supplementation has grown in popularity due to the discovery of its anabolic effects on cell signaling and protein synthesis in muscle. The current recommendation is a minimum intake of 55 mg ⋅ kg -1 . d -1 Leucine acutely stimulates skeletal muscle anabolism and can overcome the anabolic resistance of aging. The value of chronic leucine ingestion for muscle growth is still unclear. Most of the research into leucine consumption has focused on efficacy. To our knowledge, very few studies have sought to determine the maximum safe level of intake. Limited evidence suggests that intakes of ≤1250 mg ⋅ kg -1 . d -1 do not appear to have any health consequences other than short-term elevated plasma ammonia concentrations. Similarly, no adverse events have been reported for the leucine metabolite β-hydroxy-β-methylbutyrate (HMB), although no studies have tested HMB toxicity in humans. Therefore, future research is needed to evaluate leucine and HMB toxicity in the elderly and in specific health conditions. © 2016 American Society for Nutrition.
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Qureshi, Mohammad A; Khatoon, Fehmeeda; Rizvi, Moshahid A; Zafaryab, Md
2015-01-01
High toxicity and multidrug resistance associated with various standard antimicrobial drugs have necessitated search for safer alternatives in plant-derived materials. In this study, we performed biological examination of chitosan-based hydrogel film loaded with ethyl acetate Salix alba leaves extract against 11 standard laboratory strains. FTIR showed regeneration of saccharide peak in CP1A at 1047 cm(-1) and increased in height of other peaks. DSC exothermic decomposition peaks at 112 °C, 175 °C and 251 °C reveal the effect of extract on hydrogel film. From FESEM images, three-dimensional cross-linking and extract easily seen in the globular form from the surface. MTT assay on HEK 293 cells showed that CP1A was non-toxic. Minimum inhibitory concentration ranges from 4000 μg/ml to 125 μg/ml. Enterococcus faecium, Candida glabrata and Candida tropicalis were the most resistant, while Salmonella typhi and Candida guilliermondii were the most susceptible micro-organisms.
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Antibacterial Activity and Kinetics of Litsea cubeba Oil on Escherichia coli
Li, Wen-Ru; Shi, Qing-Shan; Liang, Qing; Xie, Xiao-Bao; Huang, Xiao-Mo; Chen, Yi-Ben
2014-01-01
Litsea cubeba oil is extracted from the fresh fruits of Litsea cubeba by distillation. In this study, its chemical constituents, antibacterial activity, kinetics and effects against Escherichia coli were studied. Its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were both 0.125% (v/v) by toxic food method. Moreover, the antibacterial kinetic curves indicated 0.0625% (v/v) of litsea cubeba oil was able to prolong the growth lag phase of E. coli cells to approximate 12 hours while 0.125% (v/v) of litsea cubeba oil was able to kill the cells completely. Furthermore, transmission electron microscope (TEM) observation showed most E. coli cells treated with 0.125% (v/v) of litsea cubeba oil were killed or destroyed severely within 2 hours. The litsea cubeba oil might penetrate and destroy the outer and inner membrane of E. coli cells. Thus many holes and gaps were observed on the damaged cells, which led to their death eventually. The antibacterial effects of litsea cubeba oil mainly attributed to the presence of aldehydes, which accounted for approximately 70% in its whole components analyzed by GC/MS. Based on the antimicrobial properties, litsea cubeba oil would have a broad application in the antimicrobial industry. PMID:25372706
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Cheruiyot, Dorothy J; Boyd, Robert S; Coudron, Thomas A; Cobine, Paul A
2013-06-01
Increased metal availability in the environment can be detrimental for the growth and development of all organisms in a food web. In part, this toxicity is due to biotransfer or bioaccumulation of metals between trophic levels. We evaluated the survival, growth, and development of a generalist Hemipteran predator (Podisus maculiventris) when fed herbivorous prey (Spodoptera exigua) reared on artificial diet amended with Cu, Zn, Ni, and Co. Predator nymphs were fed S. exigua larvae raised on diet amended with sublethal (Minimum Sublethal Concentration or MSC) or lethal (Minimum Lethal Concentration or MLC) concentrations of each metal, as well as control diet. We determined if metals were biotransferred or bioaccumulated from the diet to herbivore and predator, as well as if predator growth or survival was affected by herbivore diet. Podisus maculiventris fed herbivores raised on MLC levels of both Cu and Zn took significantly longer to mature to adults, whereas their overall survival was not affected by prey diet metal concentration for any metal. Adult weights were significantly reduced for predators raised on herbivores reared on diets amended with the MLC of Cu and Zn. Copper and Zn were bioaccumulated from diet to herbivore and from herbivore to predator, whereas Ni was biotransferred (although concentrations decreased as trophic level increased). The pattern for Co was more complex, with biotransfer the main outcome. Our results show that availability of metals in a food web can affect growth and development of a hemipteran predator, and that metals are transferred between trophic levels, with metal-specific biotransfer and bioaccumulation outcomes.
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Experimental Monitoring of Cr(VI) Bio-reduction Using Electrochemical Geophysics
DOE Office of Scientific and Technical Information (OSTI.GOV)
Birsen Canan; Gary R. Olhoeft; William A. Smith
2007-09-01
Many Department of Energy (DOE) sites are contaminated with highly carcinogenic hexavalent chromium (Cr(VI)). In this research, we explore the feasibility of applying complex resistivity to the detection and monitoring of microbially-induced reduction of hexavalent chromium (Cr(VI)) to a less toxic form (Cr(III)). We hope to measure the change in ionic concentration that occurs during this reduction reaction. This form of reduction promises to be an attractive alternative to more expensive remedial treatment methods. The specific goal of this research is to define the minimum and maximum concentration of the chemical and biological compounds in contaminated samples for which themore » Cr(VI) - Cr(III) reduction processes could be detected via complex resistivity. There are three sets of experiments, each comprised of three sample columns. The first experiment compares three concentrations of Cr(VI) at the same bacterial cell concentration. The second experiment establishes background samples with, and without, Cr(VI) and bacterial cells. The third experiment examines the influence of three different bacterial cell counts on the same concentration of Cr(VI). A polarization relaxation mechanism was observed between 10 and 50 Hz. The polarization mechanism, unfortunately, was not unique to bio-chemically active samples. Spectral analysis of complex resistivity data, however, showed that the frequency where the phase minimum occurred was not constant for bio-chemically active samples throughout the experiment. A significant shifts in phase minima occurred between 10 to 20 Hz from the initiation to completion of Cr(VI) reduction. This phenomena was quantified using the Cole-Cole model and the Marquardt-Levenberg nonlinear least square minimization method. The data suggests that the relaxation time and the time constant of this relaxation are the Cole-Cole parameters most sensitive to changes in biologically-induced reduction of Cr(VI).« less
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40 CFR 258.55 - Assessment monitoring program.
Code of Federal Regulations, 2013 CFR
2013-07-01
... upgradient edge of the MSWLF unit and downgradient monitoring well screen (minimum distance of travel); (5... effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or mutation. (ii) [Reserved] (j) In establishing ground-water protection...
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40 CFR 258.55 - Assessment monitoring program.
Code of Federal Regulations, 2011 CFR
2011-07-01
... upgradient edge of the MSWLF unit and downgradient monitoring well screen (minimum distance of travel); (5... effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or mutation. (ii) [Reserved] (j) In establishing ground-water protection...
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40 CFR 258.55 - Assessment monitoring program.
Code of Federal Regulations, 2012 CFR
2012-07-01
... upgradient edge of the MSWLF unit and downgradient monitoring well screen (minimum distance of travel); (5... effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or mutation. (ii) [Reserved] (j) In establishing ground-water protection...
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Ordway, Diane; Viveiros, Miguel; Leandro, Clara; Arroz, Maria Jorge; Amaral, Leonard
2002-07-01
The effect of thioridazine (TZ) was studied on the killing activity of human peripheral blood monocyte derived macrophages (HPBMDM) and of human macrophage cell line THP-1 at extracellular concentrations below those achievable clinically. These macrophages have nominal killing activity against bacteria and therefore, would not influence any activity that the compounds may have against intracellular localised Staphylococcus aureus. The results indicated that whereas TZ has an in vitro minimum inhibitory concentration (MIC) against the strains of S. aureus of 18, 0.1 mg/l of TZ in the medium completely inhibits the growth of S. aureus that has been phagocytosed by macrophages. The latter concentration was non-toxic to macrophages, did not cause cellular expression of activation marker CD69 nor induction of CD3+ T cell production of IFN-gamma, but blocked cellular proliferation and down-regulated the production of T cell-derived cytokines (IFN-gamma, IL-5). These results suggest that TZ induces intracellular bactericidal activities independent of the capacity to generate Type 1 responses against S. aureus.
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Peters, James G.; Wilber, W.G.; Crawford, Charles G.; Girardi, F.P.
1979-01-01
A digital computer model calibrated to observe stream conditions was used to evaluate water quality in West Fork Blue River, Washington County, IN. Instream dissolved-oxygen concentration averaged 96.5% of saturation at selected sites on West Fork Blue River during two 24-hour summer surveys. This high dissolved-oxygen concentration reflects small carbonaceous and nitrogenous waste loads; adequate dilution of waste by the stream; and natural reaeration. Nonpoint source waste loads accounted for an average of 53.2% of the total carbonaceous biochemical-oxygen demand and 90.2% of the nitrogenous biochemical-oxygen demand. Waste-load assimilation was studiedfor critical summer and winter low flows. Natural streamflow for these conditions was zero, so no benefit from dilution was provided. The projected stream reaeration capacity was not sufficient to maintain the minimum daily dissolved-oxygen concentration (5 milligrams per liter) in the stream with current waste-discharge restrictions. During winter low flow, ammonia toxicity, rather than dissolved-oxygen concentration, was the limiting water-quality criterion downstream from the Salem wastewater-treatment facility. (USGS)
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NASA Technical Reports Server (NTRS)
Schulz, J. R.; Anselmi, R. T.
1976-01-01
The feasibility of using free urease enzyme and ANGC-101 ion exchange resin to remove urea and ammonium ion for space system waste water applications was studied. Specifically examined is the prevention of urea and ammonia toxicity in a 30-day Orbiting Frog Otolith (OFO) flight experiment. It is shown that free urease enzyme used in conjunction with ANGC-101 ion-exchange resin and pH control can control urea and amonium ion concentration in unbuffered recirculating water. In addition, the resin does not adversely effect the bullfrogs by lowering the concentration of cations below critical minimum levels. Further investigations on bioburden control, frog waste excretion on an OFO diet, a trade-off analysis of methods of automating the urea/ammonium ion removal system and fabrication and test of a semiautomated breadboard were recommended as continuing efforts. Photographs of test equipment and test animals are shown.
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Metal transformation as a strategy for bacterial detoxification of heavy metals.
Essa, Ashraf M M; Al Abboud, Mohamed A; Khatib, Sayeed I
2018-01-01
Microorganisms can modify the chemical and physical characters of metals leading to an alteration in their speciation, mobility, and toxicity. Aqueous heavy metals solutions (Hg, Cd, Pb, Ag, Cu, and Zn) were treated with the volatile metabolic products (VMPs) of Escherichia coli Z3 for 24 h using aerobic bioreactor. The effect of the metals treated with VMPs in comparison to the untreated metals on the growth of E. coli S1 and Staphylococcus aureus S2 (local isolates) was examined. Moreover, the toxic properties of the treated and untreated metals were monitored using minimum inhibitory concentration assay. A marked reduction of the treated metals toxicity was recorded in comparison to the untreated metals. Scanning electron microscopy and energy dispersive X-ray analysis revealed the formation of metal particles in the treated metal solutions. In addition to heavy metals at variable ratios, these particles consisted of carbon, oxygen, sulfur, nitrogen elements. The inhibition of metal toxicity was attributed to the existence of ammonia, hydrogen sulfide, and carbon dioxide in the VMPs of E. coli Z3 culture that might responsible for the transformation of soluble metal ions into metal complexes. This study clarified the capability of E. coli Z3 for indirect detoxification of heavy metals via the immobilization of metal ions into biologically unavailable species. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Ceci, Andrea; Pierro, Lucia; Riccardi, Carmela; Pinzari, Flavia; Maggi, Oriana; Persiani, Anna Maria; Gadd, Geoffrey Michael; Petrangeli Papini, Marco
2015-10-01
β-Hexachlorocyclohexane (β-HCH) is a persistent organic pollutant (POP) of global concern with potentially toxic effects on humans and ecosystems. Fungal tolerance and biotransformation of toxic substances hold considerable promise in environmental remediation technologies as many fungi can tolerate extreme environmental conditions and possess efficient extracellular degradative enzymes with relatively non-specific activities. In this research, we have investigated the potential of a saprotrophic soil fungus, Penicillium griseofulvum Dierckx, isolated from soils with high concentrations of isomers of hexachlorocyclohexane, to biotransform β-HCH, the most recalcitrant isomer to microbial activity. The growth kinetics of the fungus were characterized after growth in stirred liquid Czapek-Dox medium. It was found that P. griseofulvum was able to grow in the presence of 1 mg L(-1) β-HCH and in stressful nutritional conditions at different concentrations of sucrose in the medium (0 and 5 g L(-1)). The effects of β-HCH and the toluene, used as a solvent for β-HCH addition, on P. griseofulvum were investigated by means of a Phenotype MicroArray™ technique, which suggested the activation of certain metabolic pathways as a response to oxidative stress due to the presence of the xenobiotics. Gas chromatographic analysis of β-HCH concentration confirmed biodegradation of the isomer with a minimum value of β-HCH residual concentration of 18.6%. The formation of benzoic acid derivatives as dead-end products of β-HCH biotransformation was observed and this could arise from a possible biodegradation pathway for β-HCH with important connections to fungal secondary metabolism. Copyright © 2015 Elsevier Ltd. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Shiotsuka, R.N.; Peck, R.W. Jr.; Drew, R.T.
1985-02-01
A fluidizing bed aerosol generator (FBG), designed for inhalation toxicity studies, was constructed and tested. A key design feature contributing to its operational stability was the partial masking of the screen supporting the bronze beads. This caused 20-80% of the bed to fluidize under normal operating conditions. The non-fluidizing areas functioned as reservoirs to feed the fluidizing areas. Using a bed volume of 1000 cc of bronze beads and 20 g of MnO/sub 2/ dust, the mass output rate ranged from 0.1 to 1.0 mg/min when operated at plenum pressures of 1.04 x 10/sup 2/ to 2.42 x 10/sup 2/more » kPa (minimum fluidization pressure was approximately 82.8 kPa). During daily operation at three different output rates, the FBG produced aerosols with little change in particle size distributions or concentration when operated six hours/day for five days. Furthermore, when the FBG was operated at a fixed output rate for 15 days with two recharges of MnO/sub 2/ dust, the particle size distribution did not show any cumulative increase. Thus, long-term operation of this FBG should result in a reproducible range of concentration and particle size distribution.« less
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Silver nanoparticles toxicity against airborne strains of Staphylococcus spp.
Wolny-Koładka, Katarzyna A; Malina, Dagmara K
2017-11-10
The aim of this study was to explore the toxicity of silver nanoparticles (AgNPs) synthesized by chemical reduction method assessment with regard to airborne strains of Staphylococcus spp. The first step of the experiment was the preparation of silver nanoparticle suspension. The suspension was obtained by a fast and simple chemical method involving the reduction of silver ions through a reducing factor in the presence of the suitable stabilizer required to prevent the aggregation. In the second stage, varied instrumental techniques were used for the analysis and characterization of the obtained nanostructures. Third, the bacteria of the Staphylococcus genus were isolated from the air under stable conditions with 47 sports and recreational horses, relatively. Next, isolated strains were identified using biochemical and spectrophotometric methods. The final step was the evaluation of the Staphylococcus genus sensitivity to nanosilver using the disk diffusion test. It has been proven that prepared silver nanoparticles exhibit strong antibacterial properties. The minimum inhibitory concentration for tested isolates was 30 μg/mL. It has been found that the sensitivity of Staphylococcus spp. isolated from six identified species differs considerably. The size distribution of bacterial growth inhibition zones indicates that resistance to various nanosilver concentrations is an individual strain feature, and has no connection with belonging to a specific species.
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Bills, Terry D.; Boogaard, Michael A.; Johnson, David A.; Brege, Dorance C.; Scholefield, Ronald J.; Westman, R. Wayne; Stephens, Brian E.
2003-01-01
It has long been known that the toxicity of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) is influenced by chemical and physical properties of water. As the pH, conductivity, and alkalinity of water increase, greater concentrations of TFM are required to kill sea lamprey (Petromyzon marinus) larvae. Consequently, the concentration of TFM required for effective treatment varies among streams. Brown trout (Salmo trutta) and sea lamprey larvae were exposed to a series of TFM concentrations in a continuous-flow diluter for 12 h. Twenty five exposures were conducted at various water alkalinities and pHs that treatment personnel encounter during lampricide treatments. Survival/mortality data were analyzed for lampricide concentrations that produced 50 and 99.9% mortality (LC50 and LC99.9) for sea lamprey larvae and 25 and 50% mortality (LC25 and LC50) for brown trout. Linear regression analyses were performed for each set of tests for each selected alkalinity by comparing the 12-h post exposure LC99.9 sea lamprey data and LC25 brown trout data at each pH. Mortality data from on-site toxicity tests conducted by lampricide control personnel were compared to predicted values from the pH/alkalinity prediction model. Of the 31 tests examined, 27 resulted in the LC100s (lowest TFM concentration where 100% mortality of sea lamprey was observed after 12 h of exposure) falling within 0.2 mg/L of the predicted sea lamprey minimum lethal (LC99.9) range. The pH/alkalinity prediction model provides managers with an operational tool that reduces the amount of TFM required for effective treatment while minimizing the impact on non-target organisms.
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Acute and subchronic toxicities of QX100626, a 5-HT4 receptor agonist, in rodents and Beagle dogs.
Zhang, Xiaofang; Yuan, Bojun; Mao, Yu; Dai, Xiaoyu; Zhang, Xiaodong; Lu, Guocai
2014-10-01
Serotonin 5-hydroxytryptamine 4(5-HT4) receptor agonists have been widely prescribed as a prokinetics drug for patients with gastro-esophageal reflux disease and functional dyspepsia. QX100626, one of the 5-HT4 receptor agonists, has been studied as a promising agent for this clinical use. The objective of the present study was to identify possible target organs of toxicity and propose a non-toxic dose of QX100626 for clinical usage. After single lethal dose oral and intravenous testing in rodents, some signs indicative of adverse CNS effects were observed. The minimum toxic dose of QX100626 for a single oral administration for dogs was 90.0mg/kgb.w., and the severe toxic dose was more than 300mg/kgb.w. The No Observed Adverse Effect Level (NOAEL) of QX100626 by daily oral administration for rats and dogs was 20mg/kg and 10mg/kg, respectively, whereas the minimum toxic dosages were 67 and 30mg/kg, respectively. All of the adverse effects suggested that kidney, digestive tract, as well as nervous, hematological, and respiratory systems might be the target organs of toxicity for humans induced by QX100626. The compound could be a safe alternative to other existing prokinetic agents for the treatment of functional bowel disorders. Copyright © 2014 Elsevier Inc. All rights reserved.
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6 CFR 27.204 - Minimum concentration by security issue.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 6 Domestic Security 1 2010-01-01 2010-01-01 false Minimum concentration by security issue. 27.204 Section 27.204 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Chemical Facility Security Program § 27.204 Minimum concentration by...
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Bailey, Kathryn L.; Tilton, Fred A.; Jansik, Danielle P.
2012-06-14
Foam delivery technology (FDT) uses surfactant based foam to immobilize subsurface contaminants in situ. Where traditional approaches are impractical, FDT has the potential to overcome many of the technical challenges facing the remediation of contaminated deep vadose zone environments. However, little is known about the effects these reactive chemicals may have on microorganisms inhabiting the contaminated subsurface. In addition, there are currently no standard assays to assess microbial responses to subsurface remedial treatments while these agents are under development. The objective of this study was to develop a rapid laboratory assay to assess the potential growth inhibition and/or stimulation ofmore » microorganisms following exposure to candidate FDT components. Calcium polysulfide (CPS) and several surfactants (i.e. sodium laureth sulfate (SLES), sodium dodecyl sulfate (SDS), cocamidopropyl betaine (CAPB) and NINOL40-CO) have diverse chemistries and are candidate components of FDT. Shewanella oneidensis MR-1 cultures were exposed to a range of concentrations of these chemicals to determine the minimum bactericidal concentration (MBC) and the growth and viability potential of these components. Concentrations of SDS higher than 700 {micro}M were toxic to S. oneidensis MR-1 growth over the course of four days of exposure. The relative acute toxicity order for these compounds was SDS>>CPS>>NINOL40-CO>SLES-CAPB. Dose dependent growth decreases (20 to 100 mM) were observed in the CAPB and SLES treated cultures and both CPS and NINOL 40-CO were toxic at all concentrations tested (1.45 to 7.25 mM CPS). Both SLES (20 to 100 mM) and SDS at lower concentrations (20 to 500 {micro}M) were stimulatory to S. oneidensis MR-1 indicating a capacity to be used as a carbon source. These studies also identified potentially key component characteristics, such as precipitate formation and oxygen availability, which may prove valuable in assessing the response of subsurface microorganisms. This benchtop system provides a capability to assess adverse microbial-remediation responses and contributes to the development of in situ remedial chemistries before they are deployed in the field.« less
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Bailey, Kathryn L; Tilton, Fred; Jansik, Danielle P; Ergas, Sarina J; Marshall, Matthew J; Miracle, Ann L; Wellman, Dawn M
2012-06-01
Foam delivery technology (FDT) uses surfactant based foam to immobilize subsurface contaminants in situ. Where traditional approaches are impractical, FDT has the potential to overcome many of the technical challenges facing the remediation of contaminated deep vadose zone environments. However, little is known about the effects these reactive chemicals may have on microorganisms inhabiting the contaminated subsurface. In addition, there are currently no standard assays to assess microbial responses to subsurface remedial treatments while these agents are under development. The objective of this study was to develop a rapid laboratory assay to assess the potential growth inhibition and/or stimulation of microorganisms following exposure to candidate FDT components. Calcium polysulfide (CPS) and several surfactants (i.e. sodium laureth sulfate (SLES), sodium dodecyl sulfate (SDS), cocamidopropyl betaine (CAPB) and NINOL40-CO) have diverse chemistries and are candidate components of FDT. Shewanella oneidensis MR-1 cultures were exposed to a range of concentrations of these chemicals to determine the minimum bactericidal concentration (MBC) and the growth and viability potential of these components. Concentrations of SDS higher than 700 μM were toxic to S. oneidensis MR-1 growth over the course of four days of exposure. The relative acute toxicity order for these compounds was SDS > CPS > NINOL 40-CO>SLES≥CAPB. Dose dependent growth decreases (20-100mM) were observed in the CAPB and SLES treated cultures and both CPS and NINOL 40-CO were toxic at all concentrations tested (1.45-7.25 mM CPS). Both SLES (20-100mM) and SDS at lower concentrations (20-500 μM) were stimulatory to S. oneidensis MR-1 indicating a capacity to be used as a carbon source. These studies also identified potentially key component characteristics, such as precipitate formation and oxygen availability, which may prove valuable in assessing the response of subsurface microorganisms. This benchtop system provides a capability to assess adverse microbial-remediation responses and contributes to the development of in situ remedial chemistries before they are deployed in the field. Copyright © 2012 Elsevier Inc. All rights reserved.
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Modeling ventilation time in forage tower silos.
Bahloul, A; Chavez, M; Reggio, M; Roberge, B; Goyer, N
2012-10-01
The fermentation process in forage tower silos produces a significant amount of gases, which can easily reach dangerous concentrations and constitute a hazard for silo operators. To maintain a non-toxic environment, silo ventilation is applied. Literature reviews show that the fermentation gases reach high concentrations in the headspace of a silo and flow down the silo from the chute door to the feed room. In this article, a detailed parametric analysis of forced ventilation scenarios built via numerical simulation was performed. The methodology is based on the solution of the Navier-Stokes equations, coupled with transport equations for the gas concentrations. Validation was achieved by comparing the numerical results with experimental data obtained from a scale model silo using the tracer gas testing method for O2 and CO2 concentrations. Good agreement was found between the experimental and numerical results. The set of numerical simulations made it possible to establish a simple analytical model to predict the minimum time required to ventilate a silo to make it safe to enter. This ventilation time takes into account the headspace above the forage, the airflow rate, and the initial concentrations of O2 and CO2. The final analytical model was validated with available results from the literature.
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Synergistic effect of piperonyl butoxide on acute toxicity of pyrethrins to Hyalella azteca.
Giddings, Jeffrey; Gagne, James; Sharp, Janice
2016-08-01
A series of acute toxicity tests with the amphipod Hyalella azteca was performed to quantify the synergistic effect of piperonyl butoxide (PBO) on pyrethrin toxicity. Concentrations of PBO <4 µg/L caused no toxicity enhancement, whereas toxicity increased with PBO concentrations between 4 µg/L and 15 µg/L. Additive toxicity calculations showed that true synergism accounted for an increase in pyrethrin toxicity (decrease in median lethal concentration) of 1.4-fold to 1.6-fold and varied only slightly between 4 µg/L and 15 µg/L PBO, whereas direct toxicity of PBO accounted for an additional increase in mixture toxicity (up to 3.2-fold) that was proportional to PBO concentration. The results can be used to assess the risk of measured or predicted co-occurring concentrations of PBO and pyrethrins in surface waters. Environ Toxicol Chem 2016;35:2111-2116. © 2016 SETAC. © 2016 SETAC.
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2010-01-01
Background Many bacteria among the Enterobacteria family are involved in infectious diseases and diarrhoea. Most of these bacteria become resistant to the most commonly used synthetic drugs in Cameroon. Natural substances seem to be an alternative to this problem. Thus the aim of this research was to investigate the in vitro antibacterial activity of the methanol and aqueous-methanol extracts of Sida rhombifolia Linn (Malvaceae) against seven pathogenic bacteria involved in diarrhoea. Acute toxicity of the most active extract was determined and major bioactive components were screened. Methods The agar disc diffusion and the agar dilution method were used for the determination of inhibition diameters and the Minimum Inhibitory Concentration (MICs) respectively. The acute toxicity study was performed according WHO protocol. Results The aqueous-methanol extract (1v:4v) was the most active with diameters of inhibition zones ranging from 8.7 - 23.6 mm, however at 200 μg/dic this activity was relatively weak compared to gentamycin. The MICs of the aqueous-methanol extract (1v:4v) varied from 49.40 to 78.30 μg/ml. Salmonella dysenteriae was the most sensitive (49.40 μg/ml). For the acute toxicity study, no deaths of rats were recorded. However, significant increase of some biochemical parameters such as aspartate amino-transferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and creatinine (CRT) were found. The phytochemical analysis of the aqueous methanol extract indicated the presence of tannins, polyphenols, alkaloids, glycosides, flavonoids and saponins Conclusion The results showed that the aqueous-methanol extract of S. rhombifolia exhibited moderate antibacterial activity. Some toxic effects were found when rats received more than 8 g/kg bw of extract. Antibacterial; Enterobacteria; Acute toxicity; Phytochemical analysis PMID:20663208
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Li, Tong; Liu, Shu-Shen; Qu, Rui; Liu, Hai-Ling
2017-10-01
The toxicity of a mixture depends not only on the mixture concentration level but also on the mixture ratio. For a multiple-component mixture (MCM) system with a definite chemical composition, the mixture toxicity can be predicted only if the global concentration additivity (GCA) is validated. The so-called GCA means that the toxicity of any mixture in the MCM system is the concentration additive, regardless of what its mixture ratio and concentration level. However, many mixture toxicity reports have usually employed one mixture ratio (such as the EC 50 ratio), the equivalent effect concentration ratio (EECR) design, to specify several mixtures. EECR mixtures cannot simulate the concentration diversity and mixture ratio diversity of mixtures in the real environment, and it is impossible to validate the GCA. Therefore, in this paper, the uniform design ray (UD-Ray) was used to select nine mixture ratios (rays) in the mixture system of five nitrobenzene derivatives (NBDs). The representative UD-Ray mixtures can effectively and rationally describe the diversity in the NBD mixture system. The toxicities of the mixtures to Vibrio qinghaiensis sp.-Q67 were determined by the microplate toxicity analysis (MTA). For each UD-Ray mixture, the concentration addition (CA) model was used to validate whether the mixture toxicity is additive. All of the UD-Ray mixtures of five NBDs are global concentration additive. Afterwards, the CA is employed to predict the toxicities of the external mixtures from three EECR mixture rays with the NOEC, EC 30 , and EC 70 ratios. The predictive toxicities are in good agreement with the experimental toxicities, which testifies to the predictability of the mixture toxicity of the NBDs. Copyright © 2017. Published by Elsevier Inc.
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Zakiullah; Saeed, Muhammad; Muhammad, Naveed; Khan, Saeed Ahmad; Gul, Farah; Khuda, Fazli; Humayun, Muhammad; Khan, Hamayun
2012-07-01
'Naswar' is a smokeless tobacco product (STP) widely used in Pakistan. It has been correlated with oral and oesophageal cancer in recent clinical studies. The toxic effects associated with STPs have been associated with trace level contaminants present in these products. The toxin levels of Pakistani naswar are reported for the first time in this study. A total of 30 Pakistani brands of naswar were tested for a variety of toxic constituents and carcinogens such as cadmium, arsenic, lead and other carcinogenic metals, nitrite and nitrate, and nicotine and pH. The average values of all the toxins studied were well above their allowable limits, making the product a health risk for consumers. Calculated lifetime cancer risk from cadmium and lead was 1 lac (100,000) to 10 lac (1,000,000) times higher than the minimum 10E-4 (0.00001) to 10E-6 (0.000001), which is the 'target range' for potentially hazardous substances, according to the US Environmental Protection Agency. Similarly, the level of arsenic was in the range of 0.15 to 14.04 μg/g, the average being 1.25 μg/g. The estimated average bioavailable concentration of arsenic is 0.125-0.25 μg/g, which is higher than the allowable standard of 0.01 μg/g. Similarly, the average minimum daily intake of chromium and nickel was 126.97 μg and 122.01 μg, as compared to allowable 30-35 μg and 35 μg, respectively; a 4-5 times higher exposure. However, beryllium was not detected in any of the brands studied. The pH was highly basic, averaging 8.56, which favours the formation of tobacco specific amines thus making the product potentially toxic. This study validates clinical studies correlating incidence of cancer with naswar use in Pakistan. This study shows that the production, packaging, sale and consumption of naswar should be regulated so as to protect the public from the health hazards associated with its consumption.
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40 CFR 80.91 - Individual baseline determination.
Code of Federal Regulations, 2013 CFR
2013-07-01
...—6.45 Exhaust benzene emissions, complex model—33.03 mg/mile Exhaust toxics emissions, Phase I—50.67 mg/mile Exhaust toxics emissions, Phase II—104.5 mg/mile NOX emissions, Phase I—714.4 mg/mile NOX emissions, Phase II—1461. mg/mile (d) Data collection and testing requirements—(1) Minimum sampling...
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40 CFR 80.91 - Individual baseline determination.
Code of Federal Regulations, 2014 CFR
2014-07-01
...—6.45 Exhaust benzene emissions, complex model—33.03 mg/mile Exhaust toxics emissions, Phase I—50.67 mg/mile Exhaust toxics emissions, Phase II—104.5 mg/mile NOX emissions, Phase I—714.4 mg/mile NOX emissions, Phase II—1461. mg/mile (d) Data collection and testing requirements—(1) Minimum sampling...
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40 CFR 80.91 - Individual baseline determination.
Code of Federal Regulations, 2011 CFR
2011-07-01
...—6.45 Exhaust benzene emissions, complex model—33.03 mg/mile Exhaust toxics emissions, Phase I—50.67 mg/mile Exhaust toxics emissions, Phase II—104.5 mg/mile NOX emissions, Phase I—714.4 mg/mile NOX emissions, Phase II—1461. mg/mile (d) Data collection and testing requirements—(1) Minimum sampling...
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40 CFR 80.91 - Individual baseline determination.
Code of Federal Regulations, 2010 CFR
2010-07-01
...—6.45 Exhaust benzene emissions, complex model—33.03 mg/mile Exhaust toxics emissions, Phase I—50.67 mg/mile Exhaust toxics emissions, Phase II—104.5 mg/mile NOX emissions, Phase I—714.4 mg/mile NOX emissions, Phase II—1461. mg/mile (d) Data collection and testing requirements—(1) Minimum sampling...
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Besser, J.M.; Ingersoll, C.G.; Leonard, E.N.; Mount, D.R.
1998-01-01
Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. We investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia-spiked sediments reduced pore-water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by ???70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia-spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.
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Amadi, E S; Oyeka, A; Onyeagba, R A; Okoli, I; Ugbogu, O C
2007-02-01
The antimicrobial effect of cold water, hot water and ethanolic extracts of Spondias mombin and Baphia nittida on cariogenic streptococci isolated from dental caries patients attending the Ebonyi State University Teaching hospital dental clinic Abakaliki was investigated using the agar well diffusion technique. The cold water and ethanolic extracts of Baphia nittida showed inhibition zone diameter (IZD) of 10 and 12 mm respectively at 400 mg mL(-1), while the hot water showed no inhibitory effect. All extracts of Spondias mombin did not inhibit the test organism. The cold water and ethanolic extracts of Baphia nittida showed Minimum Inhibitory Concentration (MIC) of 100 and 50 mg mL(-1) respectively. The combination of the cold water extracts of the two herbs showed enhanced activity of 13 mm. Phytochemical analysis of Baphia nittida revealed the presence of flavonoids, glycosides, proteins saponins, tannins, carbohydrate and steroidal aglycone. Acute toxicity testing of Baphia nittida at a range of 250-5000 mg kg(-1) bw using mice showed no clinical signs of acute toxicity. No chemical toxicity was observed amongst rats given Baphia nittida extracts 500 and 1000 mg kg(-1) bw after 30 days. Baphia nittida may be a potential source of an antimicrobial agent for the treatment and management of dental caries.
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Shin, Jae M.; Ateia, Islam; Paulus, Jefrey R.; Liu, Hongrui; Fenno, J. Christopher; Rickard, Alexander H.; Kapila, Yvonne L.
2015-01-01
Objectives: Nisin is a lantibiotic widely used for the preservation of food and beverages. Recently, investigators have reported that nisin may have clinical applications for treating bacterial infections. The aim of this study was to investigate the effects of ultra pure food grade Nisin ZP (>95% purity) on taxonomically diverse bacteria common to the human oral cavity and saliva derived multi-species oral biofilms, and to discern the toxicity of nisin against human cells relevant to the oral cavity. Methods: The minimum inhibitory concentrations and minimum bactericidal concentrations of taxonomically distinct oral bacteria were determined using agar and broth dilution methods. To assess the effects of nisin on biofilms, two model systems were utilized: a static and a controlled flow microfluidic system. Biofilms were inoculated with pooled human saliva and fed filter-sterilized saliva for 20–22 h at 37°C. Nisin effects on cellular apoptosis and proliferation were evaluated using acridine orange/ethidium bromide fluorescent nuclear staining and lactate dehydrogenase activity assays. Results: Nisin inhibited planktonic growth of oral bacteria at low concentrations (2.5–50 μg/ml). Nisin also retarded development of multi-species biofilms at concentrations ≥1 μg/ml. Specifically, under biofilm model conditions, nisin interfered with biofilm development and reduced biofilm biomass and thickness in a dose-dependent manner. The treatment of pre-formed biofilms with nisin resulted in dose- and time-dependent disruption of the biofilm architecture along with decreased bacterial viability. Human cells relevant to the oral cavity were unaffected by the treatment of nisin at anti-biofilm concentrations and showed no signs of apoptotic changes unless treated with much higher concentrations (>200 μg/ml). Conclusion: This work highlights the potential therapeutic value of high purity food grade nisin to inhibit the growth of oral bacteria and the development of biofilms relevant to oral diseases. PMID:26150809
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Boda, Sunil Kumar; Broda, Janine; Schiefer, Frank; Weber-Heynemann, Josefine; Hoss, Mareike; Simon, Ulrich; Basu, Bikramjit; Jahnen-Dechent, Willi
2015-07-01
The emergence of multidrug resistant bacteria, especially biofilm-associated Staphylococci, urgently requires novel antimicrobial agents. The antibacterial activity of ultrasmall gold nanoparticles (AuNPs) is tested against two gram positive: S. aureus and S. epidermidis and two gram negative: Escherichia coli and Pseudomonas aeruginosa strains. Ultrasmall AuNPs with core diameters of 0.8 and 1.4 nm and a triphenylphosphine-monosulfonate shell (Au0.8MS and Au1.4MS) both have minimum inhibitory concentration (MIC) and minimum bactericidal concentration of 25 × 10(-6) m [Au]. Disc agar diffusion test demonstrates greater bactericidal activity of the Au0.8MS nanoparticles over Au1.4MS. In contrast, thiol-stabilized AuNPs with a diameter of 1.9 nm (AuroVist) cause no significant toxicity in any of the bacterial strains. Ultrasmall AuNPs cause a near 5 log bacterial growth reduction in the first 5 h of exposure, and incomplete recovery after 21 h. Bacteria show marked membrane blebbing and lysis in biofilm-associated bacteria treated with ultrasmall AuNP. Importantly, a twofold MIC dosage of Au0.8MS and Au1.4MS each cause around 80%-90% reduction in the viability of Staphylococci enveloped in biofilms. Altogether, this study demonstrates potential therapeutic activity of ultrasmall AuNPs as an effective treatment option against staphylococcal infections. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Polychlorinated biphenyl toxicity to Japanese quail as related to degree of chlorination
Hill, E.F.; Heath, R.G.; Spann, J.W.; Williams, J.D.
1974-01-01
To learn if the percentage of chlorine in a mixture of polychlorinated biphenyls (PCB's) alone determines toxicity, Japanese quail were fed diets containing Aroelor 1248, 1254, or 1260 at levels that added equal amounts of chlorine to the feed. The experiment comprised two consecutive 5-day periods; three sublethal concentrations of chlorine were evaluated during the first period and three lethal concentrations during the second period. Evaluations utilized comparisons of mortality, time to death, weight change, and food consumption. Sublethal concentrations produced no detectable effects. Lethal concentrations with equal Chlorine showed Aroelor 1248 to be less toxic at the highest chlorine concentrations, but at lower concentrations Aroelor 1254 was more toxic than Aroclor 1260. Although chlorine percentage of a PCB is positively correlated with its avian toxicity, PCB toxicity is apparently not simply a function of chlorination.
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Liposomal Drug Delivery System for Cancer Therapy: Advancement and Patents.
Jha, Sheetal; Sharma, Pramod K; Malviya, Rishabha
2016-01-01
In this review article, authors reviewed about the liposomes which are amongst various drug delivering systems for the delivery of the therapeutic agents at the target site. Advances in liposomal drug delivery systems for the cancer therapy have enhanced the therapeutic levels of the anticancer moieties. Liposomes show promising action on the tumor by incorporating less amount of drug at the target site, with minimum toxic effect and maximum therapeutic effect and thereby enhancing the bioavailability. Liposome-based drug delivery systems provide the potential to elevate the effect of drug concentration in tumor cells. Manuscript briefly describes the role of liposomes in cancer therapy and various patents based on the same. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.
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Trnovec, Tomáš; Jusko, Todd A; Šovčíková, Eva; Lancz, Kinga; Chovancová, Jana; Patayová, Henrieta; Palkovičová, L'ubica; Drobná, Beata; Langer, Pavel; Van den Berg, Martin; Dedik, Ladislav; Wimmerová, Soňa
2013-08-01
Toxic equivalency factors (TEFs) are an important component in the risk assessment of dioxin-like human exposures. At present, this concept is based mainly on in vivo animal experiments using oral dosage. Consequently, the current human TEFs derived from mammalian experiments are applicable only for exposure situations in which oral ingestion occurs. Nevertheless, these "intake" TEFs are commonly-but incorrectly-used by regulatory authorities to calculate "systemic" toxic equivalents (TEQs) based on human blood and tissue concentrations, which are used as biomarkers for either exposure or effect. We sought to determine relative effect potencies (REPs) for systemic human concentrations of dioxin-like mixture components using thyroid volume or serum free thyroxine (FT4) concentration as the outcomes of interest. We used a benchmark concentration and a regression-based approach to compare the strength of association between each dioxin-like compound and the thyroid end points in 320 adults residing in an organochlorine-polluted area of eastern Slovakia. REPs calculated from thyroid volume and FT4 were similar. The regression coefficient (β)-derived REP data from thyroid volume and FT4 level were correlated with the World Health Organization (WHO) TEF values (Spearman r = 0.69, p = 0.01 and r = 0.62, p = 0.03, respectively). The calculated REPs were mostly within the minimum and maximum values for in vivo REPs derived by other investigators. Our REPs calculated from thyroid end points realistically reflect human exposure scenarios because they are based on chronic, low-dose human exposures and on biomarkers reflecting body burden. Compared with previous results, our REPs suggest higher sensitivity to the effects of dioxin-like compounds.
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Belapurkar, Pranoti; Goyal, Pragya; Kar, Anand
2016-01-01
The bioaccumulation of heavy metals including chromium (VI) (Cr (VI)) and lead (II) (Pb (II)) causes fatal toxicity in humans. Some naturally occurring bacterial genera such as Bacillus and Pseudomonas help in bioremediation of these heavy metals and some of the species of Bacillus are proven probiotics. However, no study has been conducted on Bacillus coagulans , which is a proven probiotic species of genus Bacillus . The primary objective of the present study was to assess the potential of a proven probiotic, B. coagulans , marketed as "Sporlac-DS," to survive in the presence of Cr (VI) and Pb (II) and its ability to reduce its concentration in vitro . The Minimum inhibitory concentration (MIC) of the organism for Cr (VI) and Pb (II) was determined followed by its biochemical and morphological characterization. Its antibiotic sensitivity and probiotic efficacy were assessed. Further, its bioremediation capacity was observed in vitro by determining the residual Cr (VI) and Pb (II) concentration after 72 h. B. coagulans could tolerate up to 512 ppm concentration of Cr (VI) and had an MIC of 128 ppm for Pb (II). After 72 h, the organism reduced 32 ppm Cr (VI) and 64 ppm Pb (II) by 93% and 89%, respectively. When B. coagulans was studied before and after growing on Cr (VI) and Pb (II) for 24 h, an increase was seen in sensitivity toward the tested antibiotics whereas no change was observed in morphological and biochemical characters. It also showed no change in their bile and acid tolerance, indicating that it retains its probiotic efficacy. The tested probiotic B. coagulans may have a potential role in bioremediation of Cr (VI) and Pb (II), in vivo .
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Belapurkar, Pranoti; Goyal, Pragya; Kar, Anand
2016-01-01
Introduction: The bioaccumulation of heavy metals including chromium (VI) (Cr (VI)) and lead (II) (Pb (II)) causes fatal toxicity in humans. Some naturally occurring bacterial genera such as Bacillus and Pseudomonas help in bioremediation of these heavy metals and some of the species of Bacillus are proven probiotics. However, no study has been conducted on Bacillus coagulans, which is a proven probiotic species of genus Bacillus. Objectives: The primary objective of the present study was to assess the potential of a proven probiotic, B. coagulans, marketed as “Sporlac-DS,” to survive in the presence of Cr (VI) and Pb (II) and its ability to reduce its concentration in vitro. Materials and Methods: The Minimum inhibitory concentration (MIC) of the organism for Cr (VI) and Pb (II) was determined followed by its biochemical and morphological characterization. Its antibiotic sensitivity and probiotic efficacy were assessed. Further, its bioremediation capacity was observed in vitro by determining the residual Cr (VI) and Pb (II) concentration after 72 h. Results: B. coagulans could tolerate up to 512 ppm concentration of Cr (VI) and had an MIC of 128 ppm for Pb (II). After 72 h, the organism reduced 32 ppm Cr (VI) and 64 ppm Pb (II) by 93% and 89%, respectively. When B. coagulans was studied before and after growing on Cr (VI) and Pb (II) for 24 h, an increase was seen in sensitivity toward the tested antibiotics whereas no change was observed in morphological and biochemical characters. It also showed no change in their bile and acid tolerance, indicating that it retains its probiotic efficacy. Conclusion: The tested probiotic B. coagulans may have a potential role in bioremediation of Cr (VI) and Pb (II), in vivo. PMID:28216949
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da Silveira, Walteçá Louis Lima; Damasceno, Bolivar P G L; Ferreira, Laura F; Ribeiro, Izabel L S; Silva, Karolyne S; Silva, André Leandro; Giannini, Maria José Mendes; da Silva-Júnior, Arnóbio Antônio; de Oliveira, Anselmo Gomes; do Egito, E Sócrates Tabosa
2016-01-01
Amphotericin B eye drops are widely used in the treatment of ocular infections. However, amphotericin's toxicity leads to low patient compliance and aggravation of symptoms. This work describes the development of a microemulsion system containing amphotericin B, aiming for its use in ocular applications. The microemulsion was developed by the titration technique. The physicochemical characteristics were determined with both loaded and unloaded amphotericin B-microemulsion. The nanostructures were analyzed by polarized light microscopy. The microdilution method was used to establish the minimum inhibitory concentration against fungal strains, and, therefore, evaluate the microemulsion activity. Additionally, in order to evaluate the microemulsion toxicity an in vitro toxicity assay against red blood cells was performed. The performed studies showed that the presence of amphotericin B loaded into the system did not induce serious changes in the physicochemical properties of the microemulsion when compared to the unloaded system. The spectrophotometric studies depicted amphotericin B-self-associated species, which allow predicting its behavior in vitro. The high pressure liquid chromatography results revealed high drug content entrapment in the microemulsion droplet. Finally, the amphotericin B-microemulsion in vitro susceptibility test showed high activity against Candida strains and a low toxicity profile against red blood cells when compared to Fungizone®. The physicochemical characterization of the microemulsion demonstrated that its characteristics are compatible with the topical ocular route, making it eligible for consideration as a new and interesting amphotericin B-deliverydosage form to be used as eye drop formulation.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Leonard, Kara Lynne, E-mail: karalynne.kerr@gmail.com; Hepel, Jaroslaw T.; Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island
2013-03-01
Purpose: To evaluate dose-volume parameters and the interfraction interval (IFI) as they relate to cosmetic outcome and normal tissue effects of 3-dimensional conformal radiation therapy (3D-CRT) for accelerated partial breast irradiation (APBI). Methods and Materials: Eighty patients were treated by the use of 3D-CRT to deliver APBI at our institutions from 2003-2010 in strict accordance with the specified dose-volume constraints outlined in the National Surgical Adjuvant Breast and Bowel Project B39/Radiation Therapy Oncology Group 0413 (NSABP-B39/RTOG 0413) protocol. The prescribed dose was 38.5 Gy in 10 fractions delivered twice daily. Patients underwent follow-up with assessment for recurrence, late toxicity, andmore » overall cosmetic outcome. Tests for association between toxicity endpoints and dosimetric parameters were performed with the chi-square test. Univariate logistic regression was used to evaluate the association of interfraction interval (IFI) with these outcomes. Results: At a median follow-up time of 32 months, grade 2-4 and grade 3-4 subcutaneous fibrosis occurred in 31% and 7.5% of patients, respectively. Subcutaneous fibrosis improved in 5 patients (6%) with extended follow-up. Fat necrosis developed in 11% of women, and cosmetic outcome was fair/poor in 19%. The relative volume of breast tissue receiving 5%, 20%, 50%, 80%, and 100% (V5-V100) of the prescribed dose was associated with risk of subcutaneous fibrosis, and the volume receiving 50%, 80%, and 100% (V50-V100) was associated with fair/poor cosmesis. The mean IFI was 6.9 hours, and the minimum IFI was 6.2 hours. The mean and minimum IFI values were not significantly associated with late toxicity. Conclusions: The incidence of moderate to severe late toxicity, particularly subcutaneous fibrosis and fat necrosis and resulting fair/poor cosmesis, remains high with continued follow-up. These toxicity endpoints are associated with several dose-volume parameters. Minimum and mean IFI values were not associated with late toxicity.« less
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The NRC has examined the availability of toxicity endpoints for industrial chemicals and concluded that many of these chemicals lack even minimum testing. One way of carrying out risk assessments of chemicals having insufficient experimental data is by using Quantitative Structur...
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Evaluation of ceftiofur–PHBV microparticles in rats
Vilos, Cristian; Constandil, Luis; Rodas, Paula I; Cantin, Mario; Zepeda, Katherine; Herrera, Natalia; Velasquez, Luis A
2014-01-01
Despite the high number of antibiotics used for the treatment of infectious disease in animals, the development of slow release formulations presents a significant challenge, particularly in using novel biomaterials with low cost. In this report, we studied the pharmacokinetics, toxicity, and therapeutic activity of ceftiofur–PHBV (ceftiofur–poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) in rats. The pharmacokinetic study demonstrated a sustained release of ceftiofur into the bloodstream, with detectable levels over the minimum inhibitory concentration for at least 17 days after a single intramuscular injection of ceftiofur–PHBV (10 mg/kg weight). In addition, the toxicological evaluation of biochemical, hematological, and coagulation blood parameters at the therapeutic dose demonstrated the safety of ceftiofur–PHBV, with no adverse effects. In addition, ceftiofur–PHBV exhibited a therapeutic effect for a longer time period than the nonencapsulated ceftiofur in rats challenged with Salmonella Typhimurium. The slow release of ceftiofur from the ceftiofur–PHBV, its low toxicity in the blood parameters evaluated, and the efficacy in the rats infected with Salmonella Typhimurium make ceftiofur–PHBV a strong candidate for biotechnological applications in the veterinary industry. PMID:24936127
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Li, Dan; Li, Litao; Ma, Yunlong; Zhuang, Yaping; Li, Dawei; Shen, Hong; Wang, Xing; Yang, Fei; Ma, Yuanzheng; Wu, Decheng
2017-03-28
Currently, the major issues in the treatment of osteoarticular tuberculosis (TB) after implant placement are low drug concentration at the infected focus and drug resistance resulting from the long-term chemotherapy. The application of drug-loaded polymeric multilayers on implantable devices offers a promising solution to the problems. Herein, a poly(ethylene glycol)-based hydrogel film embedded with isoniazid (INH)-loaded alginate microparticles was fixed to Ti implants via adhesive polydopamine, subsequently capped by poly(lactic-co-glycolic acid) membranes for the sustained and localized delivery of the anti-TB drug. The antibacterial efficacy of the released INH was confirmed by a 4.5 ± 0.8 cm inhibition zone formed in the fourth week after inoculation of Mycobacterium tuberculosis. The INH-loaded Ti implants showed no toxicity to the osteoblast cell and provided a consistent drug release for nearly one week in vitro. The release profile in vivo showed a high local concentration and low systemic exposure. The local INH concentration could be kept higher than its minimum inhibitory concentration over a period of 8 weeks, which proves that it is a promising strategy to improve the severe osteoarticular TB treatment.
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Kulow, Megan; Zibaee, Fahimeh; Allard, Marianne; Döpfer, Dörte
2015-11-01
Infectious claw diseases continue to plague cattle in intensively managed husbandry systems. Poor foot hygiene and constant moist environments lead to the infection and spread of diseases such as digital dermatitis (hairy heel warts), interdigital dermatitis, and interdigital phlegmon (foot rot). Currently, copper sulfate and formalin are the most widely used disinfecting agents in bovine footbaths; however, the industry could benefit from more environmentally and worker friendly substitutes. This study determined the in vitro minimum inhibitory concentrations and minimum bactericidal concentrations of Thymox (Laboratoire M2, Sherbrooke, Québec, Canada) for a selection of microorganisms related to infectious bovine foot diseases. Thymox is a broad-spectrum agricultural disinfectant that is nontoxic, noncorrosive, and readily biodegradable. The values for minimum inhibitory concentration and minimum bactericidal concentration indicated that Thymox inhibited growth and killed the various species of microorganisms under study at much lower concentrations compared with the recommended working concentration of a 1% solution. Overall, the values found in this study of minimum inhibitory concentration and minimum bactericidal concentration of Thymox show its potential as an alternative antibacterial agent used in bovine footbaths; however, field trials are needed to determine its effectiveness for the control and prevention of infectious claw diseases. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
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Besser, J.M.; Brumbaugh, W.G.; May, T.W.; Ingersoll, C.G.
2003-01-01
We evaluated the partitioning and toxicity of cadmium (Cd) and copper (Cu) spiked into formulated sediments containing two types of organic matter (OM), i.e., cellulose and humus. Amendments of cellulose up to 12.5% total organic carbon (TOC) did not affect partitioning of Cd or Cu between sediment and pore water and did not significantly affect the toxicity of spiked sediments in acute toxicity tests with the amphipod Hyalella azteca. In contrast, amendments of natural humus shifted the partitioning of both Cd and Cu toward greater concentrations in sediment and lesser concentrations in pore water and significantly reduced toxic effects of both metals. Thresholds for toxicity, based on measured metal concentrations in whole sediment, were greater for both Cd and Cu in sediments amended with a low level of humus (2.9% TOC) than in sediments without added OM. Amendments with a high level of humus (8.9% TOC) eliminated toxicity at the highest spike concentrations of both metals (sediment concentrations of 12.4 ??g Cd/g and 493 ??g Cu/g). Concentrations of Cd in pore water associated with acute toxicity were similar between sediments with and without humus amendments, suggesting that toxicity of Cd was reduced primarily by sorption to sediment OM. However, toxic effects of Cu in humus treatments were associated with greater pore-water concentrations than in controls, suggesting that toxicity of Cu was reduced both by sorption and by complexation with soluble ligands. Both sorption and complexation by OM tend to make proposed sediment quality guidelines (SQGs) based on total metal concentrations more protective for high-OM sediments. Our results suggest that the predictive ability of SQGs could be improved by models of metal interactions with natural OM in sediment and pore water.
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Besser, John M; Brumbaugh, William G; May, Thomas W; Ingersoll, Christopher G
2003-04-01
We evaluated the partitioning and toxicity of cadmium (Cd) and copper (Cu) spiked into formulated sediments containing two types of organic matter (OM), i.e., cellulose and humus. Amendments of cellulose up to 12.5% total organic carbon (TOC) did not affect partitioning of Cd or Cu between sediment and pore water and did not significantly affect the toxicity of spiked sediments in acute toxicity tests with the amphipod Hyalella azteca. In contrast, amendments of natural humus shifted the partitioning of hoth Cd and Cu toward greater concentrations in sediment and lesser concentrations in pore water and significantly reduced toxic effects of both metals. Thresholds for toxicity, based on measured metal concentrations in whole sediment, were greater for both Cd and Cu in sediments amended with a low level of humus (2.9% TOC) than in sediments without added OM. Amendments with a high level of humus (8.9% TOC) eliminated toxicity at the highest spike concentrations of both metals (sediment concentrations of 12.4 microg Cd/g and 493 microg Cu/g). Concentrations of Cd in pore water associated with acute toxicity were similar between sediments with and without humus amendments, suggesting that toxicity of Cd was reduced primarily by sorption to sediment OM. However, toxic effects of Cu in humus treatments were associated with greater pore-water concentrations than in controls, suggesting that toxicity of Cu was reduced both by sorption and by complexation with soluble ligands. Both sorption and complexation by OM tend to make proposed sediment quality guidelines (SQGs) based on total metal concentrations more protective for high-OM sediments. Our results suggest that the predictive ability of SQGs could be improved by models of metal interactions with natural OM in sediment and pore water.
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Rojas-Bedolla, Edgar Isaac; Gutiérrez-Pérez, Jorge Luis; Arenas-López, Mario Iván; González-Chávez, Marco Martin; Zapata-Morales, Juan Ramón; Mendoza-Macías, Claudia Leticia; Carranza-Álvarez, Candy; Maldonado-Miranda, Juan José; Deveze-Álvarez, Martha Alicia; Alonso-Castro, Angel Josabad
2018-06-12
Celtis pallida Torr (Cannabaceae) is employed as a folk medicine for the treatment of inflammation, pain, skin infections, and diarrhea, among other diseases. The purpose of this work was to assess the chemical composition, the in vitro and in vivo toxicity, the antimicrobial, anti-inflammatory, antidiarrheal, antinociceptive, locomotor, and sedative effects of an ethanolic extract obtained from Celtis pallida aerial parts (CPE). The composition of CPE was carried out by GC-MS. The in vitro and in vivo toxic activity of CPE was estimated with the comet assay (10-1000 µg/ml) for 5 h in peripheral blood mononuclear cells, and the acute toxicity test (500-5000 mg/kg p.o.), for 14 days, respectively. The antimicrobial effect of CPE was evaluated using the minimum inhibitory concentration (MIC) assay, whereas the antidiarrheal activity (10-200 mg/kg p.o.) was calculated using the castor oil test. The antinociceptive effects of CPE (50-200 mg/kg p.o.) were estimated with the acetic acid and formalin tests, as well as the hot plate test. The sedative and locomotor activities of CPE (50-200 mg/kg p.o.) were assessed with the pentobarbital-induced sleeping time test and the rotarod test, respectively. The main compound found in CPE was the triterpene ursolic acid (22% of the extract). CPE at concentrations of 100 µg/ml or higher induced genotoxicity in vitro and showed low in vivo toxicity (LD 50 > 5000 mg/kg p.o.). Additionally, CPE lacked (MIC > 400 µg/ml) antimicrobial activity but exerts antinociceptive (ED 50 = 12.5 ± 1.5 mg/kg) and antidiarrheal effects (ED 50 = 2.8 mg/kg), without inducing sedative effects or altering the locomotor activity. The antinociceptive activity of CPE suggests the participation of adrenoceptors, as well as the nitric oxide/cyclic guanosine monophosphate (cGMP) pathway. C. pallida exerts its antinociceptive effects probably mediated by the nitric oxide/cyclic guanosine monophosphate (cGMP) pathway. Copyright © 2018 Elsevier B.V. All rights reserved.
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Phillips, Bryn M; Anderson, Brian S; Hunt, John W; Clark, Sara L; Voorhees, Jennifer P; Tjeerdema, Ron S; Casteline, Jane; Stewart, Margaret
2009-02-01
Phase I whole sediment toxicity identification evaluation (TIE) methods have been developed to characterize the cause of toxicity as organic chemicals, metals, or ammonia. In Phase II identification treatments, resins added to whole sediment to reduce toxicity caused by metals and organics can be separated and eluted much like solid-phase extraction (SPE) columns are eluted for interstitial water. In this study, formulated reference sediments spiked with toxic concentrations of copper, fluoranthene, and nonylphenol were subjected to whole sediment and interstitial water TIE treatments to evaluate Phase I and II TIE procedures for identifying the cause of toxicity to Hyalella azteca. Phase I TIE treatments consisted of adding adsorbent resins to whole sediment, and using SPE columns to remove spiked chemicals from interstitial water. Phase II treatments consisted of eluting resins and SPE columns and the preparation and testing of eluates for toxicity and chemistry. Whole sediment resins and SPE columns significantly reduced toxicity, and the eluates from all treatments contained toxic concentrations of the spiked chemical except for interstitial water fluoranthene. Toxic unit analysis based on median lethal concentrations (LC50s) allowed for the comparison of chemical concentrations among treatments, and demonstrated that the bioavailability of some chemicals was reduced in some samples and treatments. The concentration of fluoranthene in the resin eluate closely approximated the original interstitial water concentration, but the resin eluate concentrations of copper and nonylphenol were much higher than the original interstitial water concentrations. Phase II whole sediment TIE treatments provided complementary lines of evidence to the interstitial water TIE results.
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Yu, Li; Kong, Fanxiang; Zhang, Min; Yang, Zhen; Shi, Xiaoli; Du, Mingyong
2014-01-01
Lake Chaohu, which is a large, shallow, hypertrophic freshwater lake in southeastern China, has been experiencing lake-wide toxic Microcystis blooms in recent decades. To illuminate the relationships between microcystin (MC) production, the genotypic composition of the Microcystis community and environmental factors, water samples and associated environmental data were collected from June to October 2012 within Lake Chaohu. The Microcystis genotypes and MC concentrations were quantified using quantitative real-time PCR (qPCR) and HPLC, respectively. The results showed that the abundances of Microcystis genotypes and MC concentrations varied on spatial and temporal scales. Microcystis exists as a mixed population of toxic and non-toxic genotypes, and the proportion of toxic Microcystis genotypes ranged from 9.43% to 87.98%. Both Pearson correlation and stepwise multiple regressions demonstrated that throughout the entire lake, the abundances of total and toxic Microcystis and MC concentrations showed significant positive correlation with the total phosphorus and water temperature, suggesting that increases in temperature together with the phosphorus concentrations may promote more frequent toxic Microcystis blooms and higher concentrations of MC. Whereas, dissolved inorganic carbon (DIC) was negatively correlated with the abundances of total and toxic Microcystis and MC concentrations, indicating that rising DIC concentrations may suppress toxic Microcystis abundance and reduce the MC concentrations in the future. Therefore, our results highlight the fact that future eutrophication and global climate change can affect the dynamics of toxic Microcystis blooms and hence change the MC levels in freshwater. PMID:25474494
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Deepak, R; Jayapradha, R
2015-03-01
The aims of the study were to evaluate the effects of a biosurfactant obtained from a novel Bacillus thuringiensis on Fusarium oxysporum to determine the morphological changes in the structure of the fungi and its biofilm in the presence of the biosurfactant and to evaluate the toxicity of the biosurfactant on HEp-2 human epithelial cell lines. The strain was screened and isolated from petroleum contaminated soil based on the E24 emulsification index. The biosurfactant was produced on glycerol, extracted using chloroform:methanol system and purified using HPLC. The purified fraction showing both surface activity (emulsification and oil-spread activity) and anti-fusarial activity (agar well diffusion method) was studied using FT-IR and MALDI-TOF MS, respectively. The minimum inhibitory concentration (MIC) and the biofilm inhibitory concentration (BIC) were determined using dilution method. The effect of biosurfactant on the morphology of Fusarium oxysporum was monitored using light microscopy and confocal laser scanning microscopy (for biofilm). The purified surfactant showed the presence of functional groups like that of surfactin in the FT-IR spectra and MALDI-TOF MS estimated the molecular weight as 700Da. The MIC and BIC were estimated to be 0.05 and 0.5mg/mL, respectively. The molecule was also non-toxic to HEp-2 cell lines at 10× MIC. A non-toxic and effective anti-Fusarium biosurfactant, that is both safe for human use and to the environment, has been characterized. The growth and metabolite production using glycerol (major byproduct of biodiesel and soap industries) also adds up to the efficiency and ecofriendly nature of this biosurfactant. Copyright © 2014 Elsevier Masson SAS. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Deville, Curtiland, E-mail: deville@uphs.upenn.edu; Vapiwala, Neha; Hwang, Wei-Ting
2012-03-15
Purpose: To assess whether whole-pelvis (WP) intensity modulated radiation therapy (IMRT) for prostate cancer (PCa) after prostatectomy is associated with increased toxicity compared to prostate-bed only (PB) IMRT. Methods and Materials: All patients (n = 67) undergoing postprostatectomy IMRT to 70.2 Gy at our institution from January 2006 to January 2009 with minimum 12-month follow-up were divided into WP (n = 36) and PB (n = 31) comparison groups. WP patients received initial pelvic nodal IMRT to 45 Gy. Pretreatment demographics, bladder and rectal dose-volume histograms, and maximum genitourinary (GU) and gastrointestinal (GI) toxicities were compared. Logistic regression models evaluatedmore » uni- and multivariate associations between pretreatment demographics and toxicities. Results: Pretreatment demographics including age and comorbidities were similar between groups. WP patients had higher Gleason scores, T stages, and preoperative prostate-specific antigen (PSA) levels, and more WP patients underwent androgen deprivation therapy (ADT). WP minimum (Dmin) and mean bladder doses, bladder volumes receiving more than 5 Gy (V5) and V20, rectal Dmin, and PB bladder and rectal V65 were significantly increased. Maximum acute GI toxicity was Grade 2 and was increased for WP (61%) vs. PB (29%) patients (p = 0.001); there was no significant difference in acute Grade {>=}2 GU toxicity (22% WP vs. 10% PB; p = 0.193), late Grade {>=}2 GI toxicity (3% WP vs. 0% PB; p = 0.678), or late Grade {>=}2 GU toxicity (28% WP vs. 19% PB; p = 0.274) with 25-month median follow-up (range, 12-44 months). On multivariate analysis, long-term ADT use was associated with Grade {>=}2 late GU toxicity (p = 0.02). Conclusion: Despite dosimetric differences in irradiated bowel, bladder, and rectum, WP IMRT resulted only in clinically significant increased acute GI toxicity in comparison to that with PB IMRT, with no differences in GU or late GI toxicity.« less
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KuKanich, Butch; Papich, Mark; Huff, David; Stoskopf, Michael
2004-06-01
Amikacin, an aminoglycoside antimicrobial, was administered to a killer whale (Orcinus orca) and a beluga whale (Delphinapterus leucas) for the treatment of clinical signs consistent with gram-negative aerobic bacterial infections. Dosage regimens were designed to target a maximal plasma concentration 8-10 times the minimum inhibitory concentrations of the pathogen and to reduce the risk of aminoglycoside toxicity. Allometric analysis of published pharmacokinetic parameters in mature animals yielded a relationship for amikacin's volume of distribution, in milliliters, given by the equation Vd = 151.058(BW)1.043. An initial dose for amikacin was estimated by calculating the volume of distribution and targeted maximal concentration. With this information, dosage regimens for i.m. administration were designed for a killer whale and a beluga whale. Therapeutic drug monitoring was performed on each whale to assess the individual pharmacokinetic parameters. The elimination half-life (5.99 hr), volume of distribution per bioavailability (319 ml/kg). and clearance per bioavailability (0.61 ml/min/kg) were calculated for the killer whale. The elimination half-life (5.03 hr), volume of distribution per bioavailability (229 ml/kg). and clearance per bioavailability (0.53 ml/min/kg) were calculated for the beluga whale. The volume of distribution predicted from the allometric equation for both whales was similar to the calculated pharmacokinetic parameter. Both whales exhibited a prolonged elimination half-life and decreased clearance when compared with other animal species despite normal renal parameters on biochemistry panels. Allometric principles and therapeutic drug monitoring were used to accurately determine the doses in these cases and to avoid toxicity.
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Mackay, Donald; Celsie, Alena K D; Parnis, J Mark; McCarty, Lynn S; Arnot, Jon A; Powell, David E
2017-05-01
A 1-compartment toxicokinetic model is used to characterize the chemical exposure toxicity space (CETS), providing a novel graphic tool that can aid in the design of aquatic toxicity tests for fish and for interpreting their results. The graph depicts the solution to the differential equation describing the uptake kinetics of a chemical by a modeled fish under conventional bioassay conditions. The model relates the exposure concentration in the water to a dimensionless time and the onset of toxicity as determined by an estimated or assumed critical body residue or incipient lethal aqueous concentration. These concentration graphs are specific to each chemical and exposure and organism parameters and clearly demonstrate differences in toxicity between chemicals and how factors such as hydrophobicity influence the toxic endpoint. The CETS plots can also be used to assess bioconcentration test conditions to ensure that concentrations are well below toxic levels. Illustrative applications are presented using a recent set of high-quality toxicity data. Conversion of concentrations to chemical activities in the plots enables results for different baseline toxicants to be superimposed. For chemicals that have different modes of toxic action, the increased toxicity then becomes apparent. Implications for design and interpretation of aquatic toxicity tests are discussed. The model, and pictorial visualization of the time-course of aquatic toxicity tests, may contribute to improvements in test design, implementation, and interpretation, and to reduced animal usage. Environ Toxicol Chem 2017;36:1389-1396. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.
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Identification of acute toxicants in New Bedford Harbor sediments
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ho, K.T.; McKinney, R.A.; Kuhn, A.
1997-03-01
New Bedford Harbor (NBH) is a marine Superfund site contaminated with high concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and metals. Experiments were conducted to determine the causal toxic agent(s) in pore waters from New Bedford Harbor sediments to amphipods and mysid shrimp. Chemical manipulations to characterize toxicity revealed that pore-water toxicity was organic in nature. Fractionation and subsequent mass spectral identification of peaks in the toxic fraction indicated that PCBs. PAHs, and unknown compounds were present. Comparisons of PAH LC50s and PAH concentrations in this fraction indicated that the toxicity was not due to PAHs because themore » PAH concentrations were much lower than the reported PAH LC50s. One unknown peak was positively identified as bis(2-ethylhexyl) phthalate, and the other tentatively identified as pyrazole. Toxicity tests and comparison of toxicity in the blank and toxic fractions eliminated the two unknowns as toxic causal agents. The authors determined the range of PCB LC50s to fall between 10 and 110 ppb for Mysidopsis bahia and Ampelisca abdita. Concentrations of PCBs for the toxic fractions ranged from 12 to 27 ppb. This range falls within the observed PCB LC50s for M. bahia and A. abdita. Based upon these PCB concentrations, they concluded that PCBs were the acute toxic agents in NBH pore waters. Other compounds in the toxic fractions, or compounds that coeluted and were undistinguished from PCBs had minor contributions to the measured toxicity.« less
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Biver, Marc; Filella, Montserrat
2016-05-03
The toxicity of Cd being well established and that of Te suspected, the bulk, surface-normalized steady-state dissolution rates of two industrially important binary tellurides-polycrystalline cadmium and bismuth tellurides- were studied over the pH range 3-11, at various temperatures (25-70 °C) and dissolved oxygen concentrations (0-100% O2 in the gas phase). The behavior of both tellurides is strikingly different. The dissolution rates of CdTe monotonically decreased with increasing pH, the trend becoming more pronounced with increasing temperature. Activation energies were of the order of magnitude associated with surface controlled processes; they decreased with decreasing acidity. At pH 7, the CdTe dissolution rate increased linearly with dissolved oxygen. In anoxic solution, CdTe dissolved at a finite rate. In contrast, the dissolution rate of Bi2Te3 passed through a minimum at pH 5.3. The activation energy had a maximum in the rate minimum at pH 5.3 and fell below the threshold for diffusion control at pH 11. No oxygen dependence was detected. Bi2Te3 dissolves much more slowly than CdTe; from one to more than 3.5 orders of magnitude in the Bi2Te3 rate minimum. Both will readily dissolve under long-term landfill deposition conditions but comparatively slowly.
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Implicit Versus Explicit Applications of the Tissue Residue Approach, Oral Presentation
Toxic effect models based on the relationship of toxic effects to chemical concentrations within receptor organism tissues can often be reformulated to describe the relationship of toxic effects to exposure concentrations without actual specification of the tissue concentrations....
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Anti-biofilm properties of Satureja hortensis L. essential oil against periodontal pathogens.
Gursoy, Ulvi Kahraman; Gursoy, Mervi; Gursoy, Orhan Vedat; Cakmakci, Lutfu; Könönen, Eija; Uitto, Veli-Jukka
2009-08-01
Essential oils of several plants are widely used in ethnomedicine for their antimicrobial and anti-inflammatory properties. However, very limited data exist on their use in connection to periodontal diseases. The aim of the present study was to investigate the bacterial growth inhibiting and anti-biofilm effects of Satureja hortensis L. (summer savory), Salvia fruticosa M. (sage), Lavandula stoechas L. (lavender), Myrtus communis L., and Juniperus communis L. (juniper) essential oils. Chemical compositions of the essential oils were analyzed by gas chromatography-mass spectrometry, minimum inhibitor concentrations (MICs) with the agar dilution method, and anti-biofilm effects by the microplate biofilm assay. The toxicity of each essential oil was tested on cultured keratinocytes. Of the 5 essential oils, S. hortensis L. essential oil had the strongest growth inhibition effect. Subinhibitory dose of S. hortensis L. essential oil had anti-biofilm effects only against Prevotella nigrescens. Essential oils did not inhibit keratinocyte viability at the concentrations of 1 and 5 microl/ml, however at the concentration of 5 microl/ml epithelial cells detached from the culture well bottom. The present findings suggest that S. hortensis L. essential oil inhibits the growth of periodontal bacteria in the concentration that is safe on keratinocytes, however, in the subinhibitory concentration its anti-biofilm effect is limited.
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El-Sayed, Refat; Alotaibi, Hawazin H; Elhady, Heba A
2018-01-01
The synthesis of water-soluble heterocyclic compounds was verified on the basis of nonionic surfactants for use as surface-active agents. Surface characteristics such as surface and interfacial tensions, cloud point, wetting time, emulsion stability, foaming height and foaming stability were measured for these surface factors in aqueous solutions. In addition, the critical micelle concentration (CMC), the surface pressure at CMC (π cmc ), the effectiveness of surface tension reduction (pC 20 ), the maximum surface concentration (Γ ma. ) and the minimum area/molecule at the aqueous solution/air interface (A min ) were calculated. Moreover, the biodegradability for these nonionic surfactants has been investigated. Furthermore, the antimicrobial evaluation has been evaluated with some surfactants that have demonstrated a potent cytotoxicity as antibacterial, antifungal and anticancer. These surfactants have a good water solubility, low toxicity, environmentally friendly environment, high foam, good emulsifier and easy production that will be used them in various fields such as medical drugs, insecticides, detergents, emulsifiers, cosmetics, inks clothing, leather industry and oil recovery.
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Rodriguez, M C; Zamudio, F; Torres, J A; Gonzalez-Ceron, L; Possani, L D; Rodriguez, M H
1995-06-01
The effect of a synthetic cecropin-like peptide, Shiva-3, on in vitro ookinete development and on the early sporogonic stages of Plasmodium berghei in the midgut of Anopheles albimanus was investigated. Peptide concentrations of 75 and 100 microM were effective (P < 0.05) in reducing ookinete production and the number of infected mosquitoes in almost all experiments. These peptide concentrations in the midgut were not toxic for the survival of the mosquitoes. Complete inhibition was obtained if 100 microM Shiva-3 was applied in the first 8 hr of parasite development. The deleterious effect of the peptide on the parasite was effective after exposure for as short as 50 sec and the permanence of free peptide in the mosquito midgut was estimated to be of a minimum of 5 min. These observations indicate the possibility of using Shiva-like peptide genes to engineering malaria-resistant vectors as an alternative in malaria control strategies.
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Quantum cascade laser-based photoacoustic sulfuryl fluoride sensing
NASA Astrophysics Data System (ADS)
Minini, Kariza Mayra Silva; Bueno, Sâmylla Cristina Espécie; da Silva, Marcelo Gomes; Sthel, Marcelo Silva; Vargas, Helion; Angster, Judit; Miklós, András
2017-02-01
Although sulfuryl fluoride (SO2F2) is an efficient fumigant that does not react with the surface of indoor materials and does not reduce the stratospheric ozone shield, there are some concerns about its use. It is a toxic gas that attacks the central nervous system, and its global warming potential (GWP) value is 4780 for 100 years' time. Therefore, it is a clear necessity of implementing detection methods for tracing such a molecule. In this work a sensitive photoacoustic setup was built to detect SO2F2 at concentrations of parts per billion by volume (ppbv). The symmetric S-O stretching mode was excited by a continuous-wave quantum cascade laser with radiation wavenumber ranging from 1275.7 to 1269.3 cm-1. The photoacoustic signal was generated by modulating the laser wavenumber at the first longitudinal mode of the photoacoustic cell with amplitude depth of 5 × 10-3 cm-1. The detection of a minimum SO2F2 concentration of 20 ppbv was achieved.
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Antimicrobial activity and safety evaluation of peptides isolated from the hemoglobin of chickens.
Hu, Fengjiao; Wu, Qiaoxing; Song, Shuang; She, Ruiping; Zhao, Yue; Yang, Yifei; Zhang, Meikun; Du, Fang; Soomro, Majid Hussain; Shi, Ruihan
2016-12-05
Hemoglobin is a rich source of biological peptides. As a byproduct and even wastewater of poultry-slaughtering facilities, chicken blood is one of the most abundant source of hemoglobin. In this study, the chicken hemoglobin antimicrobial peptides (CHAP) were isolated and the antimicrobial and bactericidal activities were tested by the agarose diffusion assay, minimum inhibitory concentration (MIC) analysis, minimal bactericidal concentration (MBC) analysis, and time-dependent inhibitory and bactericidal assays. The results demonstrated that CHAP had potent and rapid antimicrobial activity against 19 bacterial strains, including 9 multidrug-resistant bacterial strains. Bacterial biofilm and NaCl permeability assays, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were further performed to detect the mechanism of its antimicrobial effect. Additionally, CHAP showed low hemolytic activity, embryo toxicity, and high stability in different temperatures and animal plasma. CHAP may have great potential for expanding production and development value in animal medication, the breeding industry and environment protection.
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Hardy, Mark A.; Parliman, Deborah J.; O'Dell, Ivalou
2005-01-01
Idaho has. Although erodable soils are likely a cause of elevated turbidities, suspended-sediment concentrations were not strongly correlated with turbidities. Dissolved-solids and hardness concentrations were strongly correlated. This is probably because the limestones present in some basins are more soluble than the igneous rocks that predominate in others. Low hardness in streams of northern Idaho, where watersheds are underlain by resistant igneous rocks, enhances the toxicity of some trace elements to aquatic life in these streams. Only a few measurements of dissolved-oxygen concentrations at six sites were less than 6.0 milligrams per liter, the Idaho minimum criterion for protection of aquatic organisms. High supersaturations of dissolved oxygen at four sites suggest excessive photosynthetic activity by algal communities. Nighttime monitoring would help determine whether dissolved-oxygen concentrations at these sites might fall below the Idaho criterion. Data from four sites suggest that dissolved-oxygen concentrations may have decreased over time. The pH at 15 sites sometimes fell outside the range specified (6.5-9.0) for the protection of aquatic organisms in Idaho streams. Values exceeded 9.0 at 10 sites, probably because of excessive algal photosynthetic activity in waters where carbonate rocks are present. Values were sometimes less than 6.5 at five sites in areas of mountain bedrock geology where pH is likely to be naturally low. Mining activities also may contribute to low pH at some of these sites. Inorganic nitrogen and total phosphorus concentrations commonly exceeded those considered sufficient for supporting excess algal production (0.3 and 0.1 milligrams per liter, respectively). Data from a few sites suggest that nitrogen and(or) phosphorus concentrations might be changing over time. Low concentrations of nitrogen and phosphorus at six sites, most representing forested basins, might make them good candidates as reference sites that represent naturally occurring nutrient concentrations. Trace elements examined for this report were cadmium, copper, lead, mercury, selenium, and zinc. In water, many trace-element concentrations were below the minimum analytical reporting levels. Concentrations of cadmium, copper, lead, and zinc generally were highest in mined and other mineral-rich basins in northern Idaho. Concentrations of mercury were
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Paper-based chromatic toxicity bioassay by analysis of bacterial ferricyanide reduction.
Pujol-Vila, F; Vigués, N; Guerrero-Navarro, A; Jiménez, S; Gómez, D; Fernández, M; Bori, J; Vallès, B; Riva, M C; Muñoz-Berbel, X; Mas, J
2016-03-03
Water quality assessment requires a continuous and strict analysis of samples to guarantee compliance with established standards. Nowadays, the increasing number of pollutants and their synergistic effects lead to the development general toxicity bioassays capable to analyse water pollution as a whole. Current general toxicity methods, e.g. Microtox(®), rely on long operation protocols, the use of complex and expensive instrumentation and sample pre-treatment, which should be transported to the laboratory for analysis. These requirements delay sample analysis and hence, the response to avoid an environmental catastrophe. In an attempt to solve it, a fast (15 min) and low-cost toxicity bioassay based on the chromatic changes associated to bacterial ferricyanide reduction is here presented. E. coli cells (used as model bacteria) were stably trapped on low-cost paper matrices (cellulose-based paper discs, PDs) and remained viable for long times (1 month at -20 °C). Apart from bacterial carrier, paper matrices also acted as a fluidic element, allowing fluid management without the need of external pumps. Bioassay evaluation was performed using copper as model toxic agent. Chromatic changes associated to bacterial ferricyanide reduction were determined by three different transduction methods, i.e. (i) optical reflectometry (as reference method), (ii) image analysis and (iii) visual inspection. In all cases, bioassay results (in terms of half maximal effective concentrations, EC50) were in agreement with already reported data, confirming the good performance of the bioassay. The validation of the bioassay was performed by analysis of real samples from natural sources, which were analysed and compared with a reference method (i.e. Microtox). Obtained results showed agreement for about 70% of toxic samples and 80% of non-toxic samples, which may validate the use of this simple and quick protocol in the determination of general toxicity. The minimum instrumentation requirements and the simplicity of the bioassay open the possibility of in-situ water toxicity assessment with a fast and low-cost protocol. Copyright © 2016 Elsevier B.V. All rights reserved.
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Assam, Assam J P; Dzoyem, J P; Pieme, C A; Penlap, V B
2010-07-27
Many bacteria among the Enterobacteria family are involved in infectious diseases and diarrhoea. Most of these bacteria become resistant to the most commonly used synthetic drugs in Cameroon. Natural substances seem to be an alternative to this problem. Thus the aim of this research was to investigate the in vitro antibacterial activity of the methanol and aqueous-methanol extracts of Sida rhombifolia Linn (Malvaceae) against seven pathogenic bacteria involved in diarrhoea. Acute toxicity of the most active extract was determined and major bioactive components were screened. The agar disc diffusion and the agar dilution method were used for the determination of inhibition diameters and the Minimum Inhibitory Concentration (MICs) respectively. The acute toxicity study was performed according WHO protocol. The aqueous-methanol extract (1v:4v) was the most active with diameters of inhibition zones ranging from 8.7 - 23.6 mm, however at 200 microg/dic this activity was relatively weak compared to gentamycin. The MICs of the aqueous-methanol extract (1v:4v) varied from 49.40 to 78.30 microg/ml. Salmonella dysenteriae was the most sensitive (49.40 microg/ml). For the acute toxicity study, no deaths of rats were recorded. However, significant increase of some biochemical parameters such as aspartate amino-transferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and creatinine (CRT) were found. The phytochemical analysis of the aqueous methanol extract indicated the presence of tannins, polyphenols, alkaloids, glycosides, flavonoids and saponins The results showed that the aqueous-methanol extract of S. rhombifolia exhibited moderate antibacterial activity. Some toxic effects were found when rats received more than 8 g/kg bw of extract.
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Das, Soumen; Reed McDonagh, Philip; Selvan Sakthivel, Tamil; Barkam, Swetha; Killion, Kelsey; Ortiz, Julian; Saraf, Shashank; Kumar, Amit; Gupta, Ankur; Zweit, Jamal; Seal, Sudipta
2017-03-01
Rare earth oxide (REO) materials are found naturally in earth's crust and at the nanoscale these REO nanoparticles exhibit unique thermal, electrical, and physicochemical properties. REO nanoparticles are widely used in different industrial sectors for ceramics, glass polishing, metallurgy, lasers, and magnets. Recently, some of these REO nanoparticles have been identified for their potential application in medicine, including therapy, imaging, and diagnostics. Concurrent research into the REO nanomaterials' toxicities has also raised concern for their environmental impacts. The correlation of REO nanoparticles mediated toxicity with their physiochemical properties can help to design nanoparticles with minimal effect on the environment and living organisms. In vitro assay revealed toxicity toward Human squamous epithelial cell line (CCL30) and Human umbilical vascular endothelial cells (HUVEC) at a concentration of 100 µM and higher. In vivo results showed, with the exception of CeO 2 and Gd 2 O 3 , most of the naoparticles did not clear or had minimum clearance (10-20%) from the system. Elevated levels of alanine transferase were seen for animals given each different nanoparticle, however the increases were not significant for CeO 2 and Dy 2 O 3 . Nephrotoxicity was only seen in case of Dy 2 O 3 and Gd 2 O 3 . Lastly, histological examination revealed presence of swollen hepatocytes which further confirms toxicity of the commercial REO nanomaterials. The in vivo toxicity is mainly due to excessive tissue deposition (70-90%) due to the commercial REO nanoparticles' poor physical properties (shape, stability, and extent of agglomeration). Therefore, optimization of nanoparticles physical properties is very important. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 904-917, 2017. © 2016 Wiley Periodicals, Inc.
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Nieto, J; Alvar, J; Rodríguez, C; San Andrés, M I; San Andrés, M D; González, F
2018-04-01
The major limiting factor in the use of amphotericin B (AmB) is cumulative nephrotoxicity. In previous studies, AmB mixed with Intralipid® 20% (AmB-IL), a parenteral fat emulsion, reduces its toxicity, increases its efficacy and is less expensive than other commercial amphotericin B lipid formulations. The pharmacokinetics and toxicity of the conventional deoxycholate AmB formulation (Fungizone®) and AmB-IL were compared in dogs. The pharmacokinetic of AmB was significantly modified and renal toxicity and infusion-related side effects were reduced when the drug was prepared in fat emulsion. In addition, pharmacokinetics and toxicity were evaluated after the administration of multiple doses of AmB-IL with the purpose of determining an optimal treatment protocol in dogs. When using a consecutive day administration regime, there was a significant drug accumulation together with an increase in creatinine values after each dose. However, when using three doses per week administration regime, similar maximum and minimum plasma concentrations were maintained. During the four weeks of treatment a moderate increase in the creatinine values was observed but none of the treatments were ended prematurely. All these data suggest that Intralipid®, similar to that seen previously in humans, favors AmB distribution to the organs, decreasing drug toxicity and increasing its therapeutic index in the dogs. The dose protocol evaluated (25mg/m 2 /48h/three times per week) produces maintenance of AmB plasma levels that were close to that obtained by others authors after administration of liposomal formulations of AmB and that have been demonstrated to be clinically effective. Copyright © 2018 Elsevier Ltd. All rights reserved.
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Hariharan, G; Purvaja, R; Ramesh, R
2014-01-01
Acute and chronic toxicity tests were conducted on green mussel (Perna viridis) to determine the adverse effects of lead (Pb). Exposure of organisms to acute toxicity test for 96 h and lethal concentration (LC(50)) was the endpoint of the test. Acute toxicity for 96-h LC(50) and 95% confidence intervals of P. viridis was 2.62 ± 0.12 (2.62-3.24) mg/L Pb. Chronic toxicity tests revealed that survival of exposed organisms decreased with elevated exposure concentrations. No-observed-effect concentration (NOEC) and lowest-observed-effect concentration (LOEC) were calculated based on survival of test organisms. Results of this study demonstrated an increase in toxicity in test organisms with rise in exposure time and concentration. In this study, histology and biochemical enzymes, namely, catalase, reduced glutathione, glutathione S-transferase, and lipid peroxides, were correlated with chronic value and survival endpoints of P. viridis after chronic exposure to Pb. Biochemical and histological responses to different concentrations of Pb were assessed and significant differences were observed between control and increasing exposure concentrations. Biomarker studies in internal organs confirmed that the observed changes are due to adverse effects of Pb. This assessment of toxicity was the first step to determining the seawater quality criteria for marine organisms.
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Traudt, Elizabeth M; Ranville, James F; Meyer, Joseph S
2017-04-18
Multiple metals are usually present in surface waters, sometimes leading to toxicity that currently is difficult to predict due to potentially non-additive mixture toxicity. Previous toxicity tests with Daphnia magna exposed to binary mixtures of Ni combined with Cd, Cu, or Zn demonstrated that Ni and Zn strongly protect against Cd toxicity, but Cu-Ni toxicity is more than additive, and Ni-Zn toxicity is slightly less than additive. To consider multiple metal-metal interactions, we exposed D. magna neonates to Cd, Cu, Ni, or Zn alone and in ternary Cd-Cu-Ni and Cd-Ni-Zn combinations in standard 48 h lethality tests. In these ternary mixtures, two metals were held constant, while the third metal was varied through a series that ranged from nonlethal to lethal concentrations. In Cd-Cu-Ni mixtures, the toxicity was less than additive, additive, or more than additive, depending on the concentration (or ion activity) of the varied metal and the additivity model (concentration-addition or independent-action) used to predict toxicity. In Cd-Ni-Zn mixtures, the toxicity was less than additive or approximately additive, depending on the concentration (or ion activity) of the varied metal but independent of the additivity model. These results demonstrate that complex interactions of potentially competing toxicity-controlling mechanisms can occur in ternary-metal mixtures but might be predicted by mechanistic bioavailability-based toxicity models.
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NASA Astrophysics Data System (ADS)
Qu, Rui; Liu, Shu-Shen; Zheng, Qiao-Feng; Li, Tong
2017-03-01
Concentration addition (CA) was proposed as a reasonable default approach for the ecological risk assessment of chemical mixtures. However, CA cannot predict the toxicity of mixture at some effect zones if not all components have definite effective concentrations at the given effect, such as some compounds induce hormesis. In this paper, we developed a new method for the toxicity prediction of various types of binary mixtures, an interpolation method based on the Delaunay triangulation (DT) and Voronoi tessellation (VT) as well as the training set of direct equipartition ray design (EquRay) mixtures, simply IDVequ. At first, the EquRay was employed to design the basic concentration compositions of five binary mixture rays. The toxic effects of single components and mixture rays at different times and various concentrations were determined by the time-dependent microplate toxicity analysis. Secondly, the concentration-toxicity data of the pure components and various mixture rays were acted as a training set. The DT triangles and VT polygons were constructed by various vertices of concentrations in the training set. The toxicities of unknown mixtures were predicted by the linear interpolation and natural neighbor interpolation of vertices. The IDVequ successfully predicted the toxicities of various types of binary mixtures.
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Qu, Rui; Liu, Shu-Shen; Zheng, Qiao-Feng; Li, Tong
2017-01-01
Concentration addition (CA) was proposed as a reasonable default approach for the ecological risk assessment of chemical mixtures. However, CA cannot predict the toxicity of mixture at some effect zones if not all components have definite effective concentrations at the given effect, such as some compounds induce hormesis. In this paper, we developed a new method for the toxicity prediction of various types of binary mixtures, an interpolation method based on the Delaunay triangulation (DT) and Voronoi tessellation (VT) as well as the training set of direct equipartition ray design (EquRay) mixtures, simply IDVequ. At first, the EquRay was employed to design the basic concentration compositions of five binary mixture rays. The toxic effects of single components and mixture rays at different times and various concentrations were determined by the time-dependent microplate toxicity analysis. Secondly, the concentration-toxicity data of the pure components and various mixture rays were acted as a training set. The DT triangles and VT polygons were constructed by various vertices of concentrations in the training set. The toxicities of unknown mixtures were predicted by the linear interpolation and natural neighbor interpolation of vertices. The IDVequ successfully predicted the toxicities of various types of binary mixtures. PMID:28287626
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Lino, Cleudiomar Inácio; Gonçalves de Souza, Igor; Borelli, Beatriz Martins; Silvério Matos, Thelma Tirone; Santos Teixeira, Iasmin Natália; Ramos, Jonas Pereira; Maria de Souza Fagundes, Elaine; de Oliveira Fernandes, Philipe; Maltarollo, Vinícius Gonçalves; Johann, Susana; de Oliveira, Renata Barbosa
2018-05-10
In the search for new antifungal agents, a novel series of fifteen hydrazine-thiazole derivatives was synthesized and assayed in vitro against six clinically important Candida and Cryptococcus species and Paracoccidioides brasiliensis. Eight compounds showed promising antifungal activity with minimum inhibitory concentration (MIC) values ranging from 0.45 to 31.2 μM, some of them being equally or more active than the drug fluconazole and amphotericin B. Active compounds were additionally tested for toxicity against human embryonic kidney (HEK-293) cells and none of them exhibited significant cytotoxicity, indicating high selectivity. Molecular modeling studies results corroborated experimental SAR results, suggesting their use in the design of new antifungal agents. Copyright © 2018 Elsevier Masson SAS. All rights reserved.
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Macchi, Fernanda Souza; Pissinate, Kenia; Villela, Anne Drumond; Abbadi, Bruno Lopes; Rodrigues-Junior, Valnês; Nabinger, Débora Dreher; Altenhofen, Stefani; Sperotto, Nathalia; da Silva Dadda, Adílio; Subtil, Fernanda Teixeira; de Freitas, Talita Freitas; Erhart Rauber, Ana Paula; Borsoi, Ana Flávia; Bonan, Carla Denise; Bizarro, Cristiano Valim; Basso, Luiz Augusto; Santos, Diógenes Santiago; Machado, Pablo
2018-06-02
Using a classical hybridization approach, a series of 1H-benzo[d]imidazoles and 3,4-dihydroquinazolin-4-ones were synthesized (39 examples) and evaluated as inhibitors of Mycobacterium tuberculosis growth. Chemical modification studies yielded potent antitubercular agents with minimum inhibitory concentration (MIC) values as low as 0.24 μM against M. tuberculosis H37Rv strain. Further, the synthesized compounds were active against four drug-resistant strains containing different levels of resistance for the first line drugs. These molecules were devoid of apparent toxicity to HepG2, HaCat, and Vero cells with IC 50s > 30 μM. Viability in mammalian cell cultures was evaluated using MTT and neutral red assays. In addition, some 3,4-dihydroquinazolin-4-ones showed low risk of cardiac toxicity, no signals of neurotoxicity or morphological alteration in zebrafish (Danio rerio) toxicity models. 3,4-Dihydroquinazolin-4-ones 9q and 9w were considered the lead compounds of these series of molecules with MIC values of 0.24 μM and 0.94 μM against M. tuberculosis H37Rv, respectively. Taken together, these data indicate that this class of compounds may furnish candidates for future development of novel anti-TB drugs. Copyright © 2018 Elsevier Masson SAS. All rights reserved.
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Quality of Wisconsin stormwater, 1989-94
Bannerman, Roger T.; Legg, Andrew D.; Greb, Steven R.
1996-01-01
Water-quality data were compiled from four urban stormwater monitoring projects conducted in Wisconsin between 1989 and 1994. These projects included monitoring in both storm-sewer pipes and urban streams. A total of 147 constitu ents were analyzed for in stormwater sampled from 10 storm-sewer pipes and four urban streams. Land uses represented by the storm-sewer watersheds included residential, commercial, industrial, and mixed. For about one-half the con stituents, at least 10 percent of the event mean con centrations exceeded the laboratory's minimum reporting limit. Detection frequencies were greater than 75 percent for many of the heavy metals and polycyclic aromatic hydrocarbons in both the storm sewer and stream samples, whereas detec tion frequencies were about 20 percent or greater for many of the pesticides in both types of sam ples. Stormwater concentrations for conventional constituents, such as suspended solids, chloride, total phosphorus, and fecal coliform bacteria were greater than minimum reporting limits almost 100 percent of the time. Concentrations of many of the constituents were high enough to say that stormwater in the storm sewers and urban streams might be contrib uting to the degradation of the streams. In this report, constituents defined as potential contami nants are those for which the laboratory minimum report limit was exceeded for at least 10 percent of the sampled storm events, and for which at least one event mean concentration exceeded an estab lished water-quality standard. Storm-sewer sam ples had event mean concentrations of lead, copper, zinc, cadmium, and silver that frequently exceeded Wisconsin's acute toxicity criteria for cold water fisheries. Wisconsin's human cancer criteria was exceeded almost 100 percent of the time for polycyclic aromatic hydrocarbons in stormwater samples from storm sewers and streams. Maximum concentrations of diazinon found in storm sewers exceeded recommended levels of diazinon. Storm-sewer samples also exceeded Wisconsin's ground-water enforcement standards for pesticides, PCB's, phthalates, and chloride. Defined by criteria in this report, poten tial contaminants included five metals (lead, zinc, copper, silver, and cadmium), nine polycyclic aro matic hydrocarbons, Bis(2-ethylhexyl)phthalate, four pesticides (DDT, atrazine, alachlor, and 2,4 D), suspended solids, chlorides, total phosphorus, BOD 5-day, and bacteria. Wisconsin stormwater quality was similar to stormwater quality monitored in other states. Nearly one-half of median concentrations of con stituents in Wisconsin stormwater were within 30 percent of the medians from other states. The clos est agreement was seen for biochemical oxygen demand, total phosphorus, and total recoverable zinc. Similarities in stormwater quality for the storm sewer and urban streams indicated the storm sewers were a major source of water to the streams during storm events. Concentrations of potential contaminants in urban streams increased dramati cally during storm events as compared to baseflow concentrations.
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Anti-MRSA malleable liposomes carrying chloramphenicol for ameliorating hair follicle targeting.
Hsu, Ching-Yun; Yang, Shih-Chun; Sung, Calvin T; Weng, Yi-Han; Fang, Jia-You
2017-01-01
Pathogens usually invade hair follicles when skin infection occurs. The accumulated bacteria in follicles are difficult to eradicate. The present study aimed to assess the cutaneous and follicular delivery of chloramphenicol (Cm)-loaded liposomes and the antibacterial activity of these liposomes against methicillin-resistant Staphylococcus aureus (MRSA). Skin permeation was conducted by in vitro Franz diffusion cell. The anti-MRSA potential was checked using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), a well diffusion test, and intracellular MRSA killing. The classic, dimyristoylphosphatidylcholine (DMPC), and deoxycholic acid (DA) liposomes had a vesicle size of 98, 132, and 239 nm, respectively. The incorporation of DMPC or DA into the liposomes increased the bilayer fluidity. The malleable vesicles containing DMPC and DA showed increased follicular Cm uptake over the control solution by 1.5- and 2-fold, respectively. The MIC and MBC of DA liposomes loaded with Cm were 62.5 and 62.5-125 μg/mL, comparable to free Cm. An inhibition zone about 2-fold higher was achieved by DA liposomes as compared to the free control at a Cm dose of 0.5 mg/mL. DA liposomes also augmented antibacterial activity on keratinocyte-infected MRSA. The deformable liposomes had good biocompatibility against keratinocytes and neutrophils (viability >80%). In vivo administration demonstrated that DA liposomes caused negligible toxicity on the skin, based on physiological examination and histology. These data suggest the potential application of malleable liposomes for follicular targeting and the treatment of MRSA-infected dermatologic conditions.
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Kedia, Akash; Prakash, Bhanu; Mishra, Prashant K; Dubey, N K
2014-01-03
The study reports potential of Cuminum cyminum (cumin) seed essential oil (EO) as a plant based shelf life enhancer against fungal and aflatoxin contamination and lipid peroxidation. The EO showed efficacy as a preservative in food systems (stored wheat and chickpeas). A total of 1230 fungal isolates were obtained from food samples, with Aspergillus flavus LHP(C)-D6 identified as the highest aflatoxin producer. Cumin seed EO was chemically characterized through GC-MS where cymene (47.08%) was found as the major component. The minimum inhibitory concentration and minimum aflatoxin inhibitory concentration of EO were 0.6 and 0.5 μl/ml respectively. The EO showed toxicity against a broad spectrum of food borne fungi. The antifungal action of EO on ergosterol content in the plasma membrane of A. flavus was determined. The EO showed strong antioxidant potential having IC50 0.092 μl/ml. As a fumigant in food systems, the EO provided sufficient protection of food samples against fungal association without affecting seed germination. In view of the antifungal and antiaflatoxigenic nature, free radical scavenging potential and efficacy in food system, cumin seed EO may be able to provide protection of food commodities against quantitative and qualitative losses, thereby enhancing their shelf life. The present investigation comprises the first report on antifungal mode of action of cumin seed EO and its efficacy as fumigant in food systems. © 2013.
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[Exposure to fluorides from drinking water in the city of Aguascalientes, Mexico].
Trejo-Vázquez, R; Bonilla-Petriciolet, A
2001-08-01
Determine the fluoride content in all the wells that supply drinking water to the city of Aguascalientes, Mexico, in order to establish the population's degree of exposure. The fluoride content of the 126 wells that supply drinking water to the city of Aguascalientes was determined, using the SPADNS method, in accordance with two Mexican regulations, NMX-AA-77-1982 and NMX-014-SSAI-1993. Using that data, we created fluoride isopleth maps showing the distribution of fluoride concentrations in the water supplies for the city of Aguascalientes. We also estimated exposure doses for the city's inhabitants. The mean analysis uncertainty was 3.9%. Seventy-three wells had a fluoride concentration of" 1.5 mg/L, which was the maximum permissible value set by the Mexican standards then in effect. All the maximum exposure doses surpassed the minimum risk level set by Agency for Toxic Substances and Disease Registry (ATSDR) of the Department of Health and Human Services of the United States of America. In the children under 1 year of age, even the minimum does was slightly higher than the ATSDR risk level. From estimating the fluoride exposure doses caused by water consumption in the city of Aguascalientes and comparing those doses with ones from other states in Mexico, we concluded that the fluoride intake in Aguascalientes represents a potential risk for inhabitants' health. The fluoride content of the city's drinking water should be reduced to 0.69 mg/L.
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Tran, S T; Bailly, J D; Tardieu, D; Durand, S; Benard, G; Guerre, P
2003-07-25
The kinetics of free sphinganine (Sa), sphinganine to sphingosine ratio (Sa/So), proteins, cholesterol, alanine aminotransferase (ALAT) and lactate dehydrogenase (LDH) were investigated in the course of fumonisin B1 (FB1) exposure in ducks (20 growing males divided into four groups of 5 receiving, respectively, a daily dose of 0, 5, 15 or 45 mg/kg FB1 via oral administration over 12 days). Descriptive statistics of these parameters were also studied in a large number of ducks not exposed to mycotoxins and free of known pathology. Although the toxin at the end of the treatment affected all the parameters investigated, only 2 days of treatment appeared necessary to increase free Sa concentrations in serum, whereas 6 days were necessary to detect a significant effect on Sa/So ratio. Significant differences between control and treated ducks were observed after 4 days of treatment for ALAT and LDH and after 6 and 8 days for cholesterol and proteins concentrations. The minimum doses of FB1 required to determine an effect were assessed using three different methods. This approach reveals that FB1 has greater effects when it is ingested at a low dose for a long time than when ingested at a high dose for a short time. Although the minimum toxic dose of FB1 in ducks remains to be determined, this result must be considered in the context of chronic exposure to the toxin, not only in avian populations.
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Soluble phosphate fertilizer production using acid effluent from metallurgical industry.
Mattiello, Edson M; Resende Filho, Itamar D P; Barreto, Matheus S; Soares, Aline R; Silva, Ivo R da; Vergütz, Leonardus; Melo, Leônidas C A; Soares, Emanuelle M B
2016-01-15
Preventive and effective waste management requires cleaner production strategies and technologies for recycling and reuse. Metallurgical industries produce a great amount of acid effluent that must be discarded in a responsible manner, protecting the environment. The focus of this study was to examine the use of this effluent to increase reactivity of some phosphate rocks, thus enabling soluble phosphate fertilizer production. The effluent was diluted in deionized water with the following concentrations 0; 12.5; 25; 50; 75% (v v(-1)), which were added to four natural phosphate rocks: Araxá, Patos, Bayovar and Catalão and then left to react for 1 h and 24 h. There was an increase in water (PW), neutral ammonium citrate (PNAC) and citric acid (PCA) soluble phosphorus fractions. Such increases were dependent of rock type while the reaction time had no significant effect (p < 0.05) on the chemical and mineralogical phosphate characteristics. Phosphate fertilizers with low toxic metal concentrations and a high level of micronutrients were produced compared to the original natural rocks. The minimum amount of total P2O5, PNAC and PW, required for national legislation for phosphate partially acidulated fertilizer, were met when using Catalão and the effluent at the concentration of 55% (v v(-1)). Fertilizer similar to partially acidulated phosphate was obtained when Bayovar with effluent at 37.5% (v v(-1)) was used. Even though fertilizers obtained from Araxá and Patos did not contain the minimum levels of total P2O5 required by legislation, they can be used as a nutrient source and for acid effluent recycling and reuse. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Brennan, Timothy C R; Turner, Christopher D; Krömer, Jens O; Nielsen, Lars K
2012-10-01
Monoterpenes are a diverse class of compounds with applications as flavors and fragrances, pharmaceuticals and more recently, jet fuels. Engineering biosynthetic pathways for monoterpene production in microbial hosts has received increasing attention. However, monoterpenes are highly toxic to many microorganisms including Saccharomyces cerevisiae, a widely used industrial biocatalyst. In this work, the minimum inhibitory concentration (MIC) for S. cerevisiae was determined for five monoterpenes: β-pinene, limonene, myrcene, γ-terpinene, and terpinolene (1.52, 0.44, 2.12, 0.70, 0.53 mM, respectively). Given the low MIC for all compounds tested, a liquid two-phase solvent extraction system to alleviate toxicity during fermentation was evaluated. Ten solvents were tested for biocompatibility, monoterpene distribution, phase separation, and price. The solvents dioctyl phthalate, dibutyl phthalate, isopropyl myristate, and farnesene showed greater than 100-fold increase in the MIC compared to the monoterpenes in a solvent-free system. In particular, the MIC for limonene in dibutyl phthalate showed a 702-fold (308 mM, 42.1 g L(-1) of limonene) improvement while cell viability was maintained above 90%, demonstrating that extractive fermentation is a suitable tool for the reduction of monoterpene toxicity. Finally, we estimated that a limonane to farnesane ratio of 1:9 has physicochemical properties similar to traditional Jet-A aviation fuel. Since farnesene is currently produced in S. cerevisiae, its use as a co-product and extractant for microbial terpene-based jet fuel production in a two-phase system offers an attractive bioprocessing option. Copyright © 2012 Wiley Periodicals, Inc.
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Characterizing toxicity of metal-contaminated sediments from mining areas
Besser, John M.; Brumbaugh, William G.; Ingersoll, Christopher G.
2015-01-01
This paper reviews methods for testing the toxicity of metals associated with freshwater sediments, linking toxic effects with metal exposure and bioavailability, and developing sediment quality guidelines. The most broadly applicable approach for characterizing metal toxicity is whole-sediment toxicity testing, which attempts to simulate natural exposure conditions in the laboratory. Standard methods for whole-sediment testing can be adapted to test a wide variety of taxa. Chronic sediment tests that characterize effects on multiple endpoints (e.g., survival, growth, and reproduction) can be highly sensitive indicators of adverse effects on resident invertebrate taxa. Methods for testing of aqueous phases (pore water, overlying water, or elutriates) are used less frequently. Analysis of sediment toxicity data focuses on statistical comparisons between responses in sediments from the study area and responses in one or more uncontaminated reference sediments. For large or complex study areas, a greater number of reference sediments is recommended to reliably define the normal range of responses in uncontaminated sediments – the ‘reference envelope’. Data on metal concentrations and effects on test organisms across a gradient of contamination may allow development of concentration-response models, which estimate metal concentrations associated with specified levels of toxic effects (e.g. 20% effect concentration or EC20). Comparisons of toxic effects in laboratory tests with measures of impacts on resident benthic invertebrate communities can help document causal relationships between metal contamination and biological effects. Total or total-recoverable metal concentrations in sediments are the most common measure of metal contamination in sediments, but metal concentrations in labile sediment fractions (e.g., determined as part of selective sediment extraction protocols) may better represent metal bioavailability. Metals released by the weak-acid extraction of acid-volatile sulfide (AVS), termed simultaneously-extracted metals (SEM), are widely used to estimate the ‘potentially-bioavailable’ fraction of metals that is not bound to sulfides (i.e., SEM-AVS). Metal concentrations in pore water are widely considered to be direct measures of metal bioavailability, and predictions of toxicity based on pore-water metal concentrations may be further improved by modeling interactions of metals with other pore-water constituents using Biotic Ligand Models. Data from sediment toxicity tests and metal analyses has provided the basis for development of sediment quality guidelines, which estimate thresholds for toxicity of metals in sediments. Empirical guidelines such as Probable Effects Concentrations or (PECs) are based on associations between sediment metal concentrations and occurrence of toxic effects in large datasets. PECs do not model bioavailable metals, but they can be used to estimate the toxicity of metal mixtures using by calculation of probable effect quotients (PEQ = sediment metal concentration/PEC). In contrast, mechanistic guidelines, such as Equilibrium Partitioning Sediment Benchmarks (ESBs) attempt to predict both bioavailability and mixture toxicity. Application of these simple bioavailability models requires more extensive chemical characterization of sediments or pore water, compared to empirical guidelines, but may provide more reliable estimates of metal toxicity across a wide range of sediment types.
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Aquatic Toxicity Screening of Fire Fighting Agents; 2003 Report
2003-06-02
Aqueous Film Forming Foam ( AFFF ), the reference toxicant. The aquatic toxicity screening consisted of an acute, static, range-finding...five concentrations of 3M Light Water Brand Aqueous Film Forming Foam ( AFFF ), the reference toxicant. The aquatic toxicity screening consisted of an...experimental foam concentrates against current Military Specification MIL-F-24385F Fire Extinguishing Agent, Aqueous Film Forming Foam
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Sediment quality assessment studies of Tampa bay, Florida
Carr, Scott R.; Chapman, Duane C.; Long, Edward R.; Windom, Herbert L.; Thursby, Glen; Sloane, Gail M.; Wolfe, Douglas A.
1996-01-01
A survey of the toxicity of sediments throughout the Tampa Bay estuary was performed as part of the National Oceanic and Atmospheric Administration's National Status and Trends Program. The objectives of the survey were to determine the spatial extent and severity of toxicity and to identify relationships between chemical contamination and toxicity. Three independent toxicity tests were performed: a 10-d amphipod survival test of the whole sediments with Ampelisca abdita, a sea urchin fertilization test of sediment pore water with Arbacia punctulata, and a 5-min Microtox® bioluminescence test with solvent extracts of the sediments. Seventy-three percent of the 165 undiluted sediment pore-water samples were significantly toxic relative to reference samples with the sea urchin fertilization test. In contrast, only 2% of the 165 samples were significantly toxic in the amphipod tests. The causes of toxicity were not determined. However, concentrations of numerous trace metals, pesticides, polychlorinated biphenyl (PCB) congeners, polycyclic aromatic hydrocarbons (PAHs), and ammonia were highly correlated with pore-water toxicity. Concentrations of many substances, especially total dichlorodiphenyltrichloroethanes (DDTs), endrin, total PCBs, certain PAHs, lead, and zinc, occurred at concentrations in the toxic samples that equaled or exceeded concentrations that have been previously associated with sediment toxicity.
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Allahdina, Ali M; Stetson, Paul F; Vitale, Susan; Wong, Wai T; Chew, Emily Y; Ferris, Fredrick L; Sieving, Paul A; Cukras, Catherine
2018-04-01
As optical coherence tomography (OCT) minimum intensity (MI) analysis provides a quantitative assessment of changes in the outer nuclear layer (ONL), we evaluated the ability of OCT-MI analysis to detect hydroxychloroquine toxicity. Fifty-seven predominantly female participants (91.2% female; mean age, 55.7 ± 10.4 years; mean time on hydroxychloroquine, 15.0 ± 7.5 years) were enrolled in a case-control study and categorized into affected (i.e., with toxicity, n = 19) and unaffected (n = 38) groups using objective multifocal electroretinographic (mfERG) criteria. Spectral-domain OCT scans of the macula were analyzed and OCT-MI values quantitated for each subfield of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. A two-sample U-test and a cross-validation approach were used to assess the sensitivity and specificity of toxicity detection according to OCT-MI criteria. The medians of the OCT-MI values in all nine of the ETDRS subfields were significantly elevated in the affected group relative to the unaffected group (P < 0.005 for all comparisons), with the largest difference found for the inner inferior subfield (P < 0.0001). The receiver operating characteristic analysis of median MI values of the inner inferior subfields showed high sensitivity and high specificity in the detection of toxicity with area under the curve = 0.99. Retinal changes secondary to hydroxychloroquine toxicity result in increased OCT reflectivity in the ONL that can be detected and quantitated using OCT-MI analysis. Analysis of OCT-MI values demonstrates high sensitivity and specificity for detecting the presence of hydroxychloroquine toxicity in this cohort and may contribute additionally to current screening practices.
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Allahdina, Ali M.; Stetson, Paul F.; Vitale, Susan; Wong, Wai T.; Chew, Emily Y.; Ferris, Fredrick L.; Sieving, Paul A.
2018-01-01
Purpose As optical coherence tomography (OCT) minimum intensity (MI) analysis provides a quantitative assessment of changes in the outer nuclear layer (ONL), we evaluated the ability of OCT-MI analysis to detect hydroxychloroquine toxicity. Methods Fifty-seven predominantly female participants (91.2% female; mean age, 55.7 ± 10.4 years; mean time on hydroxychloroquine, 15.0 ± 7.5 years) were enrolled in a case-control study and categorized into affected (i.e., with toxicity, n = 19) and unaffected (n = 38) groups using objective multifocal electroretinographic (mfERG) criteria. Spectral-domain OCT scans of the macula were analyzed and OCT-MI values quantitated for each subfield of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. A two-sample U-test and a cross-validation approach were used to assess the sensitivity and specificity of toxicity detection according to OCT-MI criteria. Results The medians of the OCT-MI values in all nine of the ETDRS subfields were significantly elevated in the affected group relative to the unaffected group (P < 0.005 for all comparisons), with the largest difference found for the inner inferior subfield (P < 0.0001). The receiver operating characteristic analysis of median MI values of the inner inferior subfields showed high sensitivity and high specificity in the detection of toxicity with area under the curve = 0.99. Conclusions Retinal changes secondary to hydroxychloroquine toxicity result in increased OCT reflectivity in the ONL that can be detected and quantitated using OCT-MI analysis. Analysis of OCT-MI values demonstrates high sensitivity and specificity for detecting the presence of hydroxychloroquine toxicity in this cohort and may contribute additionally to current screening practices. PMID:29677357
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NASA Astrophysics Data System (ADS)
García, A. R.; Grutter, M. M.; Volkamer, R. M.
2007-05-01
An environmental risk assessment for criteria pollutants and air toxics in Mexico City is presented. The data used in the study were collected by FTIR and DOAS systems during the Mexico City Metropolitan Area field campaign on April 2003 (MCMA2003). The systems were deployed in two different sites: One in downtown (Merced) and the other in the south east (CENICA). Concentrations of criteria pollutants and air toxics were obtained every 5 min and were used to obtain hourly average concentrations and the month average for April. The concentration values were used to estimate the risks of acute and chronic exposure to ambient concentrations using risk measures like hazard index, life cancer probability, life lost expectancy and maximum individual cancer risk. Results revealed that both sites have similar risk values. For acute exposure, criteria pollutants have larger risks than air toxics, but air toxics have larger risks for chronic exposure. Ambient concentrations of benzene showed the largest carcinogenic risk of the measured air toxics.
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Cheng, Dandan; Zhang, Yingying; Gao, Demin; Zhang, Hongmeng
2014-09-11
Pyrrosia petiolosa is commonly used as a traditional Chinese medicine for treatment of acute pyelonephritis, chronic bronchitis and bronchial asthma. This study aims to evaluate the antibacterial activity of the ethanol extract and its derived fractions of Pyrrosia petiolosa obtained with solvents of different polarities and to perform the anti-inflammatory screening. The powdered aerial parts of Pyrrosia petiolosa were used to extract various fractions with ethanol, petroleum ether, ethyl acetate, N-butanol and aqueous. Qualitative phytochemical screening was performed on the ethanol extract, petroleum ether fraction, ethyl acetate fraction, N-butanol fraction and aqueous fraction. The agar diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were employed to evaluate antibacterial activity of the ethanol extract and fractions. The in vitro cytotoxicity of ethanol extract and fractions was determined using MTT assay. The anti-inflammatory activity was analyzed using the mouse ear swelling induced by xylene. The phytochemical screening revealed the presence of anthraquinones, flavonoids, terpenoids, steroids, saponins, phenols and reducing sugars in the extract and fractions. Antibacterial results showed that petroleum ether fraction and N-butanol fraction inhibited all the tested microorganisms with the maximum inhibition zone of 15.25±0.35 mm. Ethyl acetate fraction also exhibited good antibacterial activity except Pseudomonas aeruginosa ATCC 27853, while extract and aqueous fraction inhibited 8 out of 13 (61.5%) of the tested microorganisms. The MIC values of ethanol extract and fractions ranged from 1.25 to 10.00 mg/mL and most of the MBC values were equal or twice as high as the corresponding MIC values. The in vitro cytotoxicity showed the ethanol extract and fractions exhibited non-toxic or low toxic activity against lung cancer cell lines A549 and mouse spleen cells. In anti-inflammatory experiment, ethanol extract at 5.0 and 10.0 mg/kg exhibited significant anti-inflammatory activity against the mouse ear swelling induced by xylene and the maximum inhibition rate reached as high as 67%. Pyrrosia petiolosa could be a potential candidate for future development of a novel antibacterial and anti-inflammatory agent. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
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Radhakrishnan, Venkatraman Srinivasan; Reddy Mudiam, Mohana Krishna; Kumar, Manish; Dwivedi, Surya Prakash; Singh, Surinder Pal; Prasad, Tulika
2018-01-01
Purpose A significant increase in the incidence of fungal infections and drug resistance has been observed in the past decades due to limited availability of broad-spectrum antifungal drugs. Nanomedicines have shown significant antimicrobial potential against various drug-resistant microbes. Silver nanoparticles (AgNps) are known for their antimicrobial properties and lower host toxicity; however, for clinical applications, evaluation of their impact at cellular and molecular levels is essential. The present study aims to understand the cellular and molecular mechanisms of AgNp-induced toxicity in a common fungal pathogen, Candida albicans. Methods AgNps were synthesized by chemical reduction method and characterized using UV–visible spectroscopy, X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy–energy dispersive X-ray spectroscopy, energy dispersive X-ray fluorescence, and zeta potential. The anti-Candida activity of AgNps was assessed by broth microdilution and spot assays. Effects of AgNps on cellular and molecular targets were assessed by monitoring the intracellular reactive oxygen species (ROS) production in the absence and presence of natural antioxidant, changes in surface morphology, cellular ultrastructure, membrane microenvironment, membrane fluidity, membrane ergosterol, and fatty acids. Results Spherical AgNps (10–30 nm) showed minimum inhibitory concentration (minimum concentration required to inhibit the growth of 90% of organisms) at 40 μg/mL. Our results demonstrated that AgNps induced dose-dependent intracellular ROS which exerted antifungal effects; however, even scavenging ROS by antioxidant could not offer protection from AgNp mediated killing. Treatment with AgNps altered surface morphology, cellular ultrastructure, membrane microenvironment, membrane fluidity, ergosterol content, and fatty acid composition, especially oleic acid. Conclusion To summarize, AgNps affected multiple cellular targets crucial for drug resistance and pathogenicity in the fungal cells. The study revealed new cellular targets of AgNps which include fatty acids like oleic acid, vital for hyphal morphogenesis (a pathogenic trait of Candida). Yeast to hypha transition being pivotal for virulence and biofilm formation, targeting virulence might emerge as a new paradigm for developing nano silver-based therapy for clinical applications in fungal therapeutics. PMID:29760548
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Xu, Qianqian; Shen, Zhiqiang; Wang, Yubo; Guo, Shijin; Li, Feng; Wang, Yanping; Zhou, Chunfeng
2013-07-09
Flos populi (male inflorescence of Populus tomentosa Carrière) has been traditionally used in East Asian countries for the treatment of various inflammatory diseases, strengthening the spleen and stomach, anti-rheumatic, anti-tumor and anti-diarrhoeal. To evaluate the in vivo or in vitro anti-diarrhoeal and anti-microbial activity of Flos populi aqueous extract. Acute toxicity of Flos populi aqueous extract (FPAE) was investigated. Castor oil-induced diarrhoea method was used to evaluate the anti-diarrhoeal activity, inhibition of defecation and diarrhoea were determined in mice, effects on castor oil-induced enteropooling, intestinal transit and intestinal fluid secretion in rats or mice. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of FPAE against strains of three clinical bacterial isolates and one reference strain were used to test the anti-microbial activity. The FPAE reduced the frequency of diarrhoea episodes and decreased the propulsion of charcoal meal through the gastrointestinal tract in a dose dependent manner. FPAE (100-500 mg/kg, p.o.) produced dose-dependent and significant (P<0.01) protection of mice against castor oil-induced diarrhoea. FPAE, dose-dependently and significantly (P< 0.01) delayed the onset of castor-oil induced diarrhoea, decreased the frequency of defecation, and reduced the severity of diarrhoea. Compared with control animals, FPAE, dose-dependently and significantly (P< 0.01) decreased the volume of castor oil-induced intestinal fluid secretion, and reduced the number, weight and wetness of faecal droppings. There was no deaths or abnormalities in behaviour seen in the acute toxicity test. The aqueous extract displayed anti-microbial effects to three species of bacteria in anti-microbial test. The findings of this study indicate that FPAE possesses anti-diarrhoeal property in rats and mice and confirm the ethnomedicinal use of Flos Populi as a valuable natural remedy for the treatment, management and/or control of diarrhoea. These results may support the fact that this plant is traditionally used to cure diarrhoea. Crown Copyright © 2013. Published by Elsevier Ireland Ltd. All rights reserved.
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Long, E.R.; MacDonald, D.D.; Cubbage, J.C.; Ingersoll, C.G.
1998-01-01
The relative abilities of sediment concentrations of simultaneously extracted trace metal: acid-volatile sulfide (SEM: AVS) and dry weight-normalized trace metals to correctly predict both toxicity and nontoxicity were compared by analysis of 77 field-collected samples. Relative to the SEM:AVS concentrations, sediment guidelines based upon dry weight-normalized concentrations were equally or slightly more accurate in predicting both nontoxic and toxic results in laboratory tests.
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Reynoso, Mercedes M.N.; Seccacini, Emilia A.; Calcagno, Javier A.; Zerba, Eduardo N.
2017-01-01
DEET and IR3535 are insect repellents present worldwide in commercial products; their efficacy has been mainly evaluated in mosquitoes. This study compares the toxicological effects and the behavioral responses induced by both repellents on the blood-sucking bug Triatoma infestans Klug (Hemiptera: Reduviidae), one of the main vectors of Chagas disease. When applied topically, the Median Lethal Dose (72 h) for DEET was 220.8 µg/insect. Using IR3535, topical application of 500 µg/insect killed no nymphs. The minimum concentration that produced repellency was the same for both compounds: 1,15 µg/cm2. The effect of a mixture DEET:IR3535 1:1 was similar to that of their pure components. Flushing out was assessed in a chamber with a shelter containing groups of ten nymphs. The repellents were aerosolized on the shelter and the number of insects leaving it was recorded for 60 min. During that time, 0.006 g/m3 of the positive control tetramethrin flushed out 76.7% of the nymphs, while 1.76 g/m3 of DEET or IR3535 flushed out 30 and 0%, respectively. The concentrations required for both compounds to produce toxicity or flushing out are too high to have any practical applications. However, they showed a promising repellency. Additional research should be done to evaluate their possible use for personal protection against T. infestans bites. PMID:28533956
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Martínez-Tomé, M J; Esquembre, R; Mallavia, R; Mateo, C R
2010-01-20
Nitrite and selenium are two bioactive compounds found in the environment which show beneficial effects for health at low levels but have toxic effects at higher doses. Consequently, quantification of both analytes in water samples results of great interest in areas such as biomedicine, food technology and environmental analysis. In a recent paper, we immobilized the inclusion complex formed between 2,3-diaminonaphthalene (DAN) and 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD) in a sol-gel matrix, in order to prepare a highly sensitive reagentless fluorescence-based sensor for the specific measurement of nitrite. Here we have explored the possibility of using the sol-gel immobilized complex to quantify selenite (Se (IV)), the more toxic form of selenium, as well as to act as a dual-analyte chemical sensor for simultaneous quantification of both nitrite and selenite in aqueous samples. Results show that (a) inclusion of DAN in HP-beta-CD and its subsequent immobilization in a sol-gel matrix do not modify the reactivity of DAN against selenite, (b) the reaction product formed (4,5-benzopiazselenol) remains into the cyclodextrin increasing considerably its fluorescence quantum yield and avoiding, therefore, its extraction into organic solvents, (c) the developed sensor can detect selenite concentrations at submicromolar level with a minimum detection limit of 13 nM, (d) the immobilized system is able to simultaneously quantify nitrite and selenite at submicromolar concentrations in natural water samples with no further sample pre-treatment.
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Antimicrobial, antibiofilm and cytotoxic activities of Hakea sericea Schrader extracts
Luís, Ângelo; Breitenfeld, Luiza; Ferreira, Susana; Duarte, Ana Paula; Domingues, Fernanda
2014-01-01
Background: Hakea sericea Schrader is an invasive shrub in Portuguese forests. Objective: The goal of this work was to evaluate the antimicrobial activity of H. sericea extracts against several strains of microorganisms, including the ability to inhibit the formation of biofilms. Additionally the cytotoxic properties of these extracts, against human cells, were assessed. Materials and Methods: The antimicrobial activity of the methanolic extracts of H. sericea was assessed by disk diffusion assay and Minimum Inhibitory Concentration (MIC) value determination. The antibiofilm activity was determined by quantification of total biofilm biomass with crystal violet. Cytotoxicity was evaluated by hemolysis assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. Results: For Gram-positive bacteria, MIC values of H. sericea methanolic extracts ranged between 0.040 and 0.625 mg/mL, whereas the fruits extract yielded the lowest MIC for several strains of microorganisms, namely, S. aureus, B. cereus, L. monocytogenes and clinical methicillin-resistant S. aureus (MRSA). Stems and fruits extract at 2.5 mg/mL effectively eradicated the biofilm of S. aureus ATCC 25923, SA 01/10 and MRSA 12/10. Regarding leaves extract, hemolysis was not observed, and in the case of stems and fruits, hemolysis was verified only for higher concentrations, suggesting its low toxicity. Fruits extract presented no toxic effect to normal human dermal fibroblasts (NHDF) cells however for concentrations of 0.017 and 0.008 mg/mL this extract was able to decrease human breast adenocarcinoma cells (MCF-7) viability in about 60%, as MTT test results had confirmed. This is a clearly demonstrator of the cytotoxicity of this extract against MCF-7 cells. PMID:24914310
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Xenon neurotoxicity in rat hippocampal slice cultures is similar to isoflurane and sevoflurane.
Brosnan, Heather; Bickler, Philip E
2013-08-01
Anesthetic neurotoxicity in the developing brain of rodents and primates has raised concern. Xenon may be a nonneurotoxic alternative to halogenated anesthetics, but its toxicity has only been studied at low concentrations, where neuroprotective effects predominate in animal models. An equipotent comparison of xenon and halogenated anesthetics with respect to neurotoxicity in developing neurons has not been made. Organotypic hippocampal cultures from 7-day-old rats were exposed to 0.75, 1, and 2 minimum alveolar concentrations (MAC) partial pressures (60% xenon at 1.2, 2.67, and 3.67 atm; isoflurane at 1.4, 1.9, and 3.8%; and sevoflurane at 3.4 and 6.8%) for 6 h, at atmospheric pressure or in a pressure chamber. Cell death was assessed 24 h later with fluorojade and fluorescent dye exclusion techniques. Xenon caused death of hippocampal neurons in CA1, CA3, and dentate regions after 1 and 2 MAC exposures, but not at 0.75 MAC. At 1 MAC, xenon increased cell death 40% above baseline (P < 0.01; ANOVA with Dunnett test). Both isoflurane and sevoflurane increased neuron death at 1 but not 2 MAC. At 1 MAC, the increase in cell death compared with controls was 63% with isoflurane and 90% with sevoflurane (both P < 0.001). Pretreatment of cultures with isoflurane (0.75 MAC) reduced neuron death after 1 MAC xenon, isoflurane, and sevoflurane. Xenon causes neuronal cell death in an in vitro model of the developing rodent brain at 1 MAC, as does isoflurane and sevoflurane at similarly potent concentrations. Preconditioning with a subtoxic dose of isoflurane eliminates this toxicity.
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Balhara, Meenakshi; Ruhil, Sonam; Dhankhar, Sandeep; Chhillar, Anil K
2015-01-01
A de novo protein named as EAF (Escherichia antifungal protein) from the cytoplasmic pool of an Escherichia coli strain (MTCC 1652), has been purified to homogeneity using anion exchange (Q-XL Sepharose) and cation exchange (SP-Sepharose) chromatography. The MIC (minimum inhibitory concentration) values of purified protein against A. fumigatus (the major pathogenic species) were found to be comparable with standard drugs i.e. 3.90 µg/ml, 3.90 µg/ml and 1.25 µg/disc via microbroth dilution assay (MDA), percentage spore germination inhibition (PSGI) and disc diffusion assay (DDA) respectively. Toxicity results confirmed that it causes no haemolysis against human RBCs upto a concentration of 1000.0 µg/ml as compared to Amphotericin B (conventional antifungal drug) that causes hundred percent haemolysis at a concentration of 37.50 µg/ml only.The purified protein demonstrated a molecular mass of 28 kDa on SDS-PAGE which was further authenticated by MALDI-TOF. Proteomic and bioinformatics studies deciphered its significant homology (72 %) with chain A-D-ribose binding protein (cluster 2 sugar binding periplasmic proteins; sequence homologues of transcription regulatory proteins) from E. coli. Single dimensional page analysis of A. fumigatusproteins with due effect of EAF (at MIC50) revealed the inhibition of two major proteins; a heat shock protein 70-Hsp70 (68 kDa); having role in protein folding and functioning andphenylanalyl-t RNA synthetase PodG subunit protein (74 kDa); involved in growth polarity in fungi. Scanning electron microscopic studies depicted homologous results. We suggest that EAF most likely belongs to a new group of proteins with potent antifungal characteristics, negligible toxicity and targeting vital proteins of fungal metabolism.
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Robust model predictive control for optimal continuous drug administration.
Sopasakis, Pantelis; Patrinos, Panagiotis; Sarimveis, Haralambos
2014-10-01
In this paper the model predictive control (MPC) technology is used for tackling the optimal drug administration problem. The important advantage of MPC compared to other control technologies is that it explicitly takes into account the constraints of the system. In particular, for drug treatments of living organisms, MPC can guarantee satisfaction of the minimum toxic concentration (MTC) constraints. A whole-body physiologically-based pharmacokinetic (PBPK) model serves as the dynamic prediction model of the system after it is formulated as a discrete-time state-space model. Only plasma measurements are assumed to be measured on-line. The rest of the states (drug concentrations in other organs and tissues) are estimated in real time by designing an artificial observer. The complete system (observer and MPC controller) is able to drive the drug concentration to the desired levels at the organs of interest, while satisfying the imposed constraints, even in the presence of modelling errors, disturbances and noise. A case study on a PBPK model with 7 compartments, constraints on 5 tissues and a variable drug concentration set-point illustrates the efficiency of the methodology in drug dosing control applications. The proposed methodology is also tested in an uncertain setting and proves successful in presence of modelling errors and inaccurate measurements. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
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Gas/liquid sensing via chemotaxis of Euglena cells confined in an isolated micro-aquarium.
Ozasa, Kazunari; Lee, Jeesoo; Song, Simon; Hara, Masahiko; Maeda, Mizuo
2013-10-21
We demonstrate on-chip gas/liquid sensing by using the chemotaxis of live bacteria (Euglena gracilis) confined in an isolated micro-aquarium, and gas/liquid permeation through porous polydimethylsiloxane (PDMS). The sensing chip consisted of one closed micro-aquarium and two separated bypass microchannels along the perimeter of the micro-aquarium. Test gas/liquid and reference samples were introduced into the two individual microchannels separately, and the gas/liquid permeated through the PDMS walls and dissolved in the micro-aquarium water, resulting in a chemical concentration gradient in the micro-aquarium. By employing the closed micro-aquarium isolated from sample flows, we succeeded in measuring the chemotaxis of Euglena for a gas substance quantitatively, which cannot be achieved with the conventional flow-type or hydro-gel-type microfluidic devices. We found positive (negative) chemotaxis for CO2 concentrations below (above) 15%, with 64 ppm as the minimum concentration affecting the cells. We also observed chemotaxis for ethanol and H2O2. By supplying culture medium via the microchannels, the Euglena culture remained alive for more than 2 months. The sensing chip is thus useful for culturing cells and using them for environmental toxicity/nutrition studies by monitoring their motion.
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Zhou, Chengcheng; Wang, Fengyan; Chen, Hui; Li, Meng; Qiao, Fulin; Liu, Zhang; Hou, Yanbo; Wu, Chunxian; Fan, Yaxun; Liu, Libing; Wang, Shu; Wang, Yilin
2016-02-17
This work reports that cationic micelles formed by cationic trimeric, tetrameric, and hexameric surfactants bearing amide moieties in spacers can efficiently kill Gram-negative E. coli with a very low minimum inhibitory concentration (1.70-0.93 μM), and do not cause obvious toxicity to mammalian cells at the concentrations used. With the increase of the oligomerization degree, the antibacterial activity of the oligomeric surfactants increases, i.e., hexameric surfactant > tetrameric surfactant > trimeric surfactant. Isothermal titration microcalorimetry, scanning electron microscopy, and zeta potential results reveal that the cationic micelles interact with the cell membrane of E. coli through two processes. First, the integrity of outer membrane of E. coli is disrupted by the electrostatic interaction of the cationic ammonium groups of the surfactants with anionic groups of E. coli, resulting in loss of the barrier function of the outer membrane. The inner membrane then is disintegrated by the hydrophobic interaction of the surfactant hydrocarbon chains with the hydrophobic domains of the inner membrane, leading to the cytoplast leakage. The formation of micelles of these cationic oligomeric surfactants at very low concentration enables more efficient interaction with bacterial cell membrane, which endows the oligomeric surfactants with high antibacterial activity.
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Ensminger, Michael; Bergin, Rick; Spurlock, Frank; Goh, Kean S
2011-04-01
The California's San Joaquin River and its tributaries including Orestimba (ORC) and Del Puerto (DPC) Creeks are listed on the 2006 US EPA Clean Water Act §303(d) list for pesticide impairment. From December 2007 through June 2008, water and sediment samples were collected from both creeks in Stanislaus County to determine concentrations of organophosphorus (OP) and pyrethroid insecticides and to identify toxicity to Ceriodaphnia dubia and Hyalella azteca. OPs were detected in almost half (10 of 21) of the water samples, at concentrations from 0.005 to 0.912 μg L(-1). Diazinon was the most frequently detected OP, followed by chlorpyrifos and dimethoate. Two water samples were toxic to C. dubia; based on median lethal concentrations (LC50), chlorpyrifos was likely the cause of this toxicity. Pyrethroids were detected more frequently in sediment samples (18 detections) than in water samples (three detections). Pyrethroid concentrations in water samples ranged from 0.005 to 0.021 μg L(-1). These concentrations were well below reported C. dubia LC50s, and toxicity was not observed in laboratory bioassays. Cyfluthrin, bifenthrin, esfenvalerate, and λ-cyhalothrin were detected in sediment samples at concentrations ranging from 1.0 to 74.4 ng g(-1), dry weight. At DPC, all but one sediment sample caused 100% toxicity to H. azteca. Based on estimated toxicity units (TUs), bifenthrin was likely responsible for this toxicity and λ-cyhalothrin also contributed. At ORC, survival of H. azteca was significantly reduced in four of the 11 sediment samples. However, pyrethroids were detected in only two of these samples. Based on TUs, bifenthrin and λ-cyhalothrin likely contributed to the toxicity.
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Brabets, Timothy P.; Whitman, Matthew S.
2002-01-01
The Camp and Costello Creek watersheds are located on the south side of Denali National Park and Preserve. The Dunkle Mine, an abandoned coal mine, is located near the mouth of Camp Creek. Due to concern about runoff from the mine and its possible effects on the water quality and aquatic habitat of Camp Creek and its receiving stream, Costello Creek, these two streams were studied during the summer runoff months (June to September) in 1999 and 2000 as part of a cooperative study with the National Park Service. Since the south side of Denali National Park and Preserve is part of the U.S. Geological Survey?s National Water-Quality Assessment Cook Inlet Basin study unit, an additional part of this study included analysis of existing water-quality data at 23 sites located throughout the south side of Denali National Park and Preserve to compare with the water quality of Camp and Costello Creeks and to obtain a broader understanding of the water quality in this area of the Cook Inlet Basin. Analysis of water column, bed sediment, fish, invertebrate, and algae data indicate no effects on the water quality of Camp Creek from the Dunkle Mine. Although several organic compounds were found in the streambed of Camp Creek, all concentrations were below recommended levels for aquatic life and most of the concentrations were below the minimum reporting level of 50 ?g/kg. Trace element concentrations of arsenic, chromium, and nickel in the bed sediments of Camp Creek exceeded threshold effect concentrations (TEC), but concentrations of these trace elements were also exceeded in streambed sediments of Costello Creek above Camp Creek. Since the percent organic carbon in Camp Creek is relatively high, the toxicity quotient of 0.55 is only slightly above the threshold value of 0.5. Costello Creek has a relatively low organic carbon content and has a higher toxicity quotient of 1.19. Analysis of the water-quality data for other streams located in the south side of Denali National Park and Preserve indicate similarities to Camp Creek and Costello Creek. Most of the streams are calcium bicarbonate/calcium bicarbonate-sulfate type water with the exception of two streams that are calcium sulfate and magnesium sulfate type water. Trace element concentrations of arsenic, chromium, and nickel in the bed sediments of 9 streams exceeded the TEC or the probable effect concentration (PEC). Seven streams exceeded the threshold value of the toxicity quotient. Analysis of trace element concentrations in bed sediment and basin characteristics for 16 watersheds by cluster and discriminant analysis techniques indicated that the watersheds could be separated into two groups based on their basin characteristics.
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Fluvial biofilms: A pertinent tool to assess beta-blockers toxicity.
Bonnineau, Chloé; Guasch, Helena; Proia, Lorenzo; Ricart, Marta; Geiszinger, Anita; Romaní, Anna M; Sabater, Sergi
2010-02-18
Among increasingly used pharmaceutical products, beta-blockers have been commonly reported at low concentrations in rivers and littoral waters of Europe and North America. Little is known about the toxicity of these chemicals in freshwater ecosystems while their presence may lead to chronic pollution. Hence, in this study the acute toxicity of 3 beta-blockers: metoprolol, propranolol and atenolol on fluvial biofilms was assessed by using several biomarkers. Some were indicative of potential alterations in biofilm algae (photosynthetic efficiency), and others in biofilm bacteria (peptidase activity, bacterial mortality). Propranolol was the most toxic beta-blocker, mostly affecting the algal photosynthetic process. The exposure to 531microg/L of propranolol caused 85% of inhibition of photosynthesis after 24h. Metoprolol was particularly toxic for bacteria. Though estimated No-Effect Concentrations (NEC) were similar to environmental concentrations, higher concentrations of the toxic (503microg/L metoprolol) caused an increase of 50% in bacterial mortality. Atenolol was the least toxic of the three tested beta-blockers. Effects superior to 50% were only observed at very high concentration (707mg/L). Higher toxicity of metoprolol and propranolol might be due to better absorption within biofilms of these two chemicals. Since beta-blockers are mainly found in mixtures in rivers, their differential toxicity could have potential relevant consequences on the interactions between algae and bacteria within river biofilms. 2009 Elsevier B.V. All rights reserved.
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Application of in Vitro Biotransformation Data and ...
The adverse biological effects of toxic substances are dependent upon the exposure concentration and the duration of exposure. Pharmacokinetic models can quantitatively relate the external concentration of a toxicant in the environment to the internal dose of the toxicant in the target tissues of an exposed organism. The exposure concentration of a toxic substance is usually not the same as the concentration of the active form of the toxicant that reaches the target tissues following absorption, distribution, and biotransformation of the parent toxicant. Biotransformation modulates the biological activity of chemicals through bioactivation and detoxication pathways. Many toxicants require biotransformation to exert their adverse biological effects. Considerable species differences in biotransformation and other pharmacokinetic processes can make extrapolation of toxicity data from laboratory animals to humans problematic. Additionally, interindividual differences in biotransformation among human populations with diverse genetics and lifestyles can lead to considerable variability in the bioactivation of toxic chemicals. Compartmental pharmacokinetic models of animals and humans are needed to understand the quantitative relationships between chemical exposure and target tissue dose as well as animal to human differences and interindividual differences in human populations. The data-based compartmental pharmacokinetic models widely used in clinical pharmacology ha
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Sensitive detection of chemical agents and toxic industrial chemicals using active open-path FTIRs
NASA Astrophysics Data System (ADS)
Walter, William T.
2004-03-01
Active open-path FTIR sensors provide more sensitive detection of chemical agents than passive FTIRs, such as the M21 RSCAAL and JSLSCAD, and at the same time identify and quantify toxic industrial chemicals (TIC). Passive FTIRs are bistatic sensors relying on infrared sources of opportunity. Utilization of earth-based sources of opportunity limits the source temperatures available for passive chemical-agent FTIR sensors to 300° K. Active FTIR chemical-agent sensors utilize silicon carbide sources, which can be operated at 1500° K. The higher source temperature provides more than an 80-times increase in the infrared radiant flux emitted per unit area in the 7 to 14 micron spectral fingerprint region. Minimum detection limits are better than 5 μgm/m3 for GA, GB, GD, GF and VX. Active FTIR sensors can (1) assist first responders and emergency response teams in their assessment of and reaction to a terrorist threat, (2) provide information on the identification of the TIC present and their concentrations and (3) contribute to the understanding and prevention of debilitating disorders analogous to the Gulf War Syndrome for military and civilian personnel.
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Fraser, Thomas W K; Khezri, Abdolrahman; Jusdado, Juan G H; Lewandowska-Sabat, Anna M; Henry, Theodore; Ropstad, Erik
2017-07-05
Alterations in zebrafish motility are used to identify neurotoxic compounds, but few have reported how methodology may affect results. To investigate this, we exposed embryos to bisphenol A (BPA) or tetrabromobisphenol A (TBBPA) before assessing larval motility. Embryos were maintained on a day/night cycle (DN) or in constant darkness, were reared in 96 or 24 well plates (BPA only), and behavioural tests were carried out at 96, 100, or 118 (BPA only) hours post fertilisation (hpf). We found that the prior photo-regime, larval age, and/or arena size influence behavioural outcomes in response to toxicant exposure. For example, methodology determined whether 10μM BPA induced hyperactivity, hypoactivity, or had no behavioural effect. Furthermore, the minimum effect concentration was not consistent between different methodologies. Finally, we observed a mechanism previously used to explain hyperactivity following BPA exposure does not appear to explain the hypoactivity observed following minor alterations in methodology. Therefore, we demonstrate how methodology can have notable implications on dose responses and behavioural outcomes in larval zebrafish motility following identical chemical exposures. As such, our results have significant consequences for human and environmental risk assessment. Copyright © 2017 Elsevier B.V. All rights reserved.
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Soucek, David J; Dickinson, Amy
2016-09-01
While it has been well established that increasing chloride concentration in water reduces the toxicity of nitrite to freshwater species, little work has been done to investigate the effect of chloride on nitrate toxicity. We conducted acute and chronic nitrate (as sodium nitrate) toxicity tests with the cladoceran Ceriodaphnia dubia and the amphipod Hyalella azteca (chronic tests only) over a range of chloride concentrations spanning natural chloride levels found in surface waters representative of watersheds of the Great Lakes Region. Chronic nitrate toxicity test results with both crustaceans were variable, with H. azteca appearing to be one of the more sensitive invertebrate species tested and C. dubia being less sensitive. While the variability in results for H. azteca were to an extent related to chloride concentration in test water that was distinctly not the case for C. dubia. We concluded that the chloride dependent toxicity of nitrate is not universal among freshwater crustaceans. An additional sodium chloride chronic toxicity test with the US Lab strain of H. azteca in the present study suggested that when present as predominantly sodium chloride and with relatively low concentrations of other ions, there is a narrow range of chloride concentrations over which this strain is most fit, and within which toxicity test data are reliable.
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Simulation of hydrodynamics, temperature, and dissolved oxygen in Beaver Lake, Arkansas, 1994-1995
Haggard, Brian; Green, W. Reed
2002-01-01
The tailwaters of Beaver Lake and other White River reservoirs support a cold-water trout fishery of significant economic yield in northwestern Arkansas. The Arkansas Game and Fish Commission has requested an increase in existing minimum flows through the Beaver Lake dam to increase the amount of fishable waters downstream. Information is needed to assess the impact of additional minimum flows on temperature and dissolved-oxygen qualities of reservoir water above the dam and the release water. A two-dimensional, laterally averaged hydrodynamic, thermal and dissolved-oxygen model was developed and calibrated for Beaver Lake, Arkansas. The model simulates surface-water elevation, currents, heat transport and dissolved-oxygen dynamics. The model was developed to assess the impacts of proposed increases in minimum flows from 1.76 cubic meters per second (the existing minimum flow) to 3.85 cubic meters per second (the additional minimum flow). Simulations included assessing (1) the impact of additional minimum flows on tailwater temperature and dissolved-oxygen quality and (2) increasing initial water-surface elevation 0.5 meter and assessing the impact of additional minimum flow on tailwater temperatures and dissolved-oxygen concentrations. The additional minimum flow simulation (without increasing initial pool elevation) appeared to increase the water temperature (<0.9 degrees Celsius) and decrease dissolved oxygen concentration (<2.2 milligrams per liter) in the outflow discharge. Conversely, the additional minimum flow plus initial increase in pool elevation (0.5 meter) simulation appeared to decrease outflow water temperature (0.5 degrees Celsius) and increase dissolved oxygen concentration (<1.2 milligrams per liter) through time. However, results from both minimum flow scenarios for both water temperature and dissolved oxygen concentration were within the boundaries or similar to the error between measured and simulated water column profile values.
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NASA Technical Reports Server (NTRS)
Major, Michael A.
2000-01-01
In an effort to modernize and minimize hazards posed by the toxic components of missile propellant, the USACHPPM has been tasked to provide a comparison of the toxicity of compounds currently in use as missile propellants and the suite of compounds proposed to replace them. This report deals with the portion of this work concerning the toxicity of the organometallic compounds used in these formulations. Toxicity assessments of the organic compounds used in these formulations are published elsewhere. In general, toxicity data were available for all the metal compounds of concern or for closely related compounds that can serve as surrogates for the assessment of toxicity. We have high confidence in the reliability of these comparisons. This report is organized by element to provide the reader with an in-depth assessment with a minimum of redundancy. The narrative will first describe general concepts about the toxicity of each metal and then provide a summary of the toxicological information available for the specific compound.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Snell, T.W.; Carmona, M.J.
Cyclically parthenogenetic zooplankters like rotifers are important tools for assessing toxicity in aquatic environments. Sexual reproduction is an essential component of rotifer life cycles, but current toxicity tests utilize only asexual reproduction. The authors compared the effects of four toxicants on asexual and sexual reproduction of the rotifer Brachionus calyciflorus. Toxicants had a differential effect on sexual and asexual reproduction, with sexual reproduction consistently the most sensitive. Concentrations of 0.2 {mu}g/ml PCP (sodium pentachlorophenate) had no effect on the asexual reproductive rate, but significantly reduced sexual reproduction. Likewise, chlorpyrifos concentrations of 0.3 {mu}g/ml had no significant effect on asexual reproduction,more » but sexual reproduction was significantly reduced. There was no difference in NOECs, LOECs, and chronic values for asexual and sexual reproduction for cadmium and naphthol tests. However, comparison of toxicant effect levels revealed that sexual reproduction was more strongly reduced at each toxicant concentration. The four toxicants tested inhibited sexual reproduction 2 to 68 times more than asexual reproduction at the lowest observed effect concentrations. Toxicants inhibited sexual reproduction in its initial step: sexual female production. Because sexual reproduction is more sensitive, toxicity tests based exclusively on asexual reproduction may not be protective of rotifer life cycles.« less
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Furutani, Eiko; Nishigaki, Yuki; Kanda, Chiaki; Takeda, Toshihiro; Shirakami, Gotaro
2013-01-01
This paper proposes a novel hypnosis control method using Auditory Evoked Potential Index (aepEX) as a hypnosis index. In order to avoid side effects of an anesthetic drug, it is desirable to reduce the amount of an anesthetic drug during surgery. For this purpose many studies of hypnosis control systems have been done. Most of them use Bispectral Index (BIS), another hypnosis index, but it has problems of dependence on anesthetic drugs and nonsmooth change near some particular values. On the other hand, aepEX has an ability of clear distinction between patient consciousness and unconsciousness and independence of anesthetic drugs. The control method proposed in this paper consists of two elements: estimating the minimum effect-site concentration for maintaining appropriate hypnosis and adjusting infusion rate of an anesthetic drug, propofol, using model predictive control. The minimum effect-site concentration is estimated utilizing the property of aepEX pharmacodynamics. The infusion rate of propofol is adjusted so that effect-site concentration of propofol may be kept near and always above the minimum effect-site concentration. Simulation results of hypnosis control using the proposed method show that the minimum concentration can be estimated appropriately and that the proposed control method can maintain hypnosis adequately and reduce the total infusion amount of propofol.
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Code of Federal Regulations, 2010 CFR
2010-10-01
... PLANNING MARKET RESEARCH 410.001 Policy. In addition to those uses listed in FAR 10.001, agencies must use the results of market research to— (a) Ensure the minimum use of hazardous or toxic materials; (b...
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Code of Federal Regulations, 2011 CFR
2011-10-01
... PLANNING MARKET RESEARCH 410.001 Policy. In addition to those uses listed in FAR 10.001, agencies must use the results of market research to— (a) Ensure the minimum use of hazardous or toxic materials; (b...
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Ingersoll, Christopher G.; Haverland, Pamela S.; Brunson, Eric L.; Canfield, Timothy J.; Dwyer, F. James; Henke, Chris; Kemble, Nile E.; Mount, David R.; Fox, Richard G.
1996-01-01
Procedures are described for calculating and evaluating sediment effect concentrations (SECs) using laboratory data on the toxicity of contaminants associated with field-collected sediment to the amphipod Hyalella azteca and the midge Chironomus riparius. SECs are defined as the concentrations of individual contaminants in sediment below which toxicity is rarely observed and above which toxicity is frequently observed. The objective of the present study was to develop SECs to classify toxicity data for Great Lake sediment samples tested with Hyalella azteca and Chironomus riparius. This SEC database included samples from additional sites across the United States in order to make the database as robust as possible. Three types of SECs were calculated from these data: (1) Effect Range Low (ERL) and Effect Range Median (ERM), (2) Threshold Effect Level (TEL) and Probable Effect Level (PEL), and (3) No Effect Concentration (NEC). We were able to calculate SECs primarily for total metals, simultaneously extracted metals, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). The ranges of concentrations in sediment were too narrow in our database to adequately evaluate SECs for butyltins, methyl mercury, polychlorinated dioxins and furans, or chlorinated pesticides. About 60 to 80% of the sediment samples in the database are correctly classified as toxic or not toxic depending on type of SEC evaluated. ERMs and ERLs are generally as reliable as paired PELs and TELs at classifying both toxic and non-toxic samples in our database. Reliability of the SECs in terms of correctly classifying sediment samples is similar between ERMs and NECs; however, ERMs minimize Type I error (false positives) relative to ERLs and minimize Type II error (false negatives) relative to NECs. Correct classification of samples can be improved by using only the most reliable individual SECs for chemicals (i.e., those with a higher percentage of correct classification). SECs calculated using sediment concentrations normalized to total organic carbon (TOC) concentrations did not improve the reliability compared to SECs calculated using dry-weight concentrations. The range of TOC concentrations in our database was relatively narrow compared to the ranges of contaminant concentrations. Therefore, normalizing dry-weight concentrations to a relatively narrow range of TOC concentrations had little influence on relative concentra of contaminants among samples. When SECs are used to conduct a preliminary screening to predict the potential for toxicity in the absence of actual toxicity testing, a low number of SEC exceedances should be used to minimize the potential for false negatives; however, the risk of accepting higher false positives is increased.
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Tashyrev, O B; Prekrasna, Ie P; Tashyreva, G O; Bielikova, O Iu
2015-01-01
Microbial communities of the Ecuadorian Andes and volcano Tungurahua were shown to be super resistant to representative toxic metals. Maximum permissible concentrations of toxic metals were 100 ppm of Hg2+, 500 ppm of Co2+ and Ni2+, 1000 and 1500 ppm of Cr(VI), 10000 and 20000 ppm of Cu2+. The effect of metal concentration increasing on the biomass growth, CO2 and H2 synthesis was investigated. Two types of response of microbial communities on the increasing of toxic metals concentrations were discovered. The first type of response is the catastrophic inhibition of microbial growth. The second type of response is the absence of microbial growth inhibition at certain metal concentration gradient. The succession of qualitative structure of Ecuadorian microbial communities was shown for the first time. Bacteria, yeasts and finally fungi consistently dominate in the microbial community at the Cu2+ concentration raising. Microorganisms resistant to ultra-high concentrations of toxic metals (e.g., 3000 ... 20000 ppm of Cu2+) were isolated from Ecuadorian ecosystems. These microorganisms are able to accumulate toxic metals.
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Concentration-response data on toxicity of pyrolysis gases from some natural and synthetic polymers
NASA Technical Reports Server (NTRS)
Hilado, C. J.; Huttlinger, N. V.
1978-01-01
Concentration-response data are presented on the toxic effects of the pyrolysis gases from some natural and synthetic polymers, using the toxicity screening test method developed at the University of San Francisco. The pyrolysis gases from wool, red oak, Douglas fir, polycaprolactam, polyether sulfone, polyaryl sulfone, and polyphenylene sulfide appeared to exhibit the concentration-response relationships commonly encountered in toxicology. Carbon monoxide seemed to be an important toxicant in the pyrolysis gases from red oak, Douglas fir, and polycaprolactam, but did not appear to have been the principal toxicant in the pyrolysis gases from polyether sulfone and polyphenylene sulfide.
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Ingersoll, Christopher G.; Dwyer, F.J.; May, T.W.
1990-01-01
Elevated concentrations of selenium (Se) have been previously measured in biota sampled from the Kesterson National Wildlife Refuge (KNWR) in the San Joaquin Valley of central California. We conducted acute and chronic toxicity tests with the cladoceran Daphnia magna and the midge Chironomus riparius to determine the toxicity or bioaccumulation of waterborne Se in a reconstituted water similar to the San Joaquin River. Daphnids were more acutely sensitive than midges to the toxic effects of inorganic Se. An organic form of Se (seleno-[L]-methionine) was extremely toxic to daphnids, but was relatively nontoxic to midges. In long-term exposure to a 6:1 mixture of selenate to selenite (a mixture representative of KNWR), the emergence time of adult midges was delayed at Se concentrations ≥ 837 μg/L. Daphnid reproduction and intrinsic rate of natural increase (r) were reduced at Se concentrations ≥ 348 μg/L and growth of adults was reduced at ≥ 156 μg/L. Whole body Mg, K and Na concentrations in daphnids were not affected by chronic Se exposure; however, whole body Ca concentration increased at intermediate Se exposure concentrations. In addition, whole body Cl concentration was reduced at 711 μg Se/L. Daphnids accumulated potentially toxic concentrations of Se from water that may adversely affect fish or waterfowl through the food chain.
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Boogaard, M.A.; Bills, T.D.; Johnson, D.A.
2003-01-01
The toxicity of the lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2',5-dichloro-4'-nitrosalicylanilide (niclosamide) to non-target fishes has been a major point of concern since their use to control larval sea lamprey (Petromyzon marinus) populations began in the early 1960s. The toxicity of TFM to several non-target fish species has been demonstrated in previous studies. However, little information is available on the toxicity of the TFM/1% niclosamide mixture. One species of particular concern is the lake sturgeon (Acipenser fulvescens). Juvenile lake sturgeon of several size ranges were exposed to determine potential effects of the lampricides to individuals present in treatment streams. Sac fry were most resistant to the lampricides followed by fingerlings in the 200 to 225 mm size range. Swim-up fry and fingerlings less than 100 mm were the most sensitive. Concentrations that produced 50% mortality (LC50s) in juvenile lake sturgeon of these smaller size ranges were at or near the minimum lethal concentrations (MLCs) required for effective control of larval sea lampreys. The mudpuppy (Necturus maculosus), an amphibian native to several tributaries of the Great Lakes, have also become a species of interest in recent years. Laboratory tests conducted with TFM and a TFM/1% niclosamide mixture on adult mudpuppies indicate that although the amphibian is sensitive to the lampricides, an adequate margin of safety exists for adult mudpuppies to survive when exposed during stream treatments. Fifteen other fish species native to streams treated with lampricides were investigated in the laboratory to determine their sensitivity to the lampricides. Centrarchids, bluegill (Lepomis macrochirus) and green sunfish (Lepomis cyanellus) were the least sensitive to TFM, while ictalurids, black bullhead (Ictalurus melas), channel catfish (Ictalurus punctatus), and tadpole madtom (Notorus gyrinus) were the most sensitive. On-site bioassays conducted before lampricide treatments also revealed that lake sturgeon, channel catfish, and whitefish (Coregonus clupeaformis) were sensitive to the lampricides although considerably less sensitive compared to sea lamprey.
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Boogaard, M.A.; Bills, T.D.; Johnson, D.A.
2003-01-01
The toxicity of the lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2???,5-dichloro-4???-nitrosalicylanilide (niclosamide) to non-target fishes has been a major point of concern since their use to control larval sea lamprey (Petromyzon marinus) populations began in the early 1960s. The toxicity of TFM to several non-target fish species has been demonstrated in previous studies. However, little information is available on the toxicity of the TFM/1 % niclosamide mixture. One species of particular concern is the lake sturgeon (Acipenser fulvescens). Juvenile lake sturgeon of several size ranges were exposed to determine potential effects of the lampricides to individuals present in treatment streams. Sac fry were most resistant to the lampricides followed by fingerlings in the 200 to 225 mm size range. Swim-up fry and fingerlings less than 100 mm were the most sensitive. Concentrations that produced 50% mortality (LC50s) in juvenile lake sturgeon of these smaller size ranges were at or near the minimum lethal concentrations (MLCs) required for effective control of larval sea lampreys. The mudpuppy (Necturus maculosus), an amphibian native to several tributaries of the Great Lakes, have also become a species of interest in recent years. Laboratory tests conducted with TFM and a TFM/1 % niclosamide mixture on adult mudpuppies indicate that although the amphibian is sensitive to the lampricides, an adequate margin of safety exists for adult mudpuppies to survive when exposed during stream treatments. Fifteen other fish species native to streams treated with lampricides were investigated in the laboratory to determine their sensitivity to the lampricides. Centrarchids, bluegill (Lepomis macrochirus) and green sunfish (Lepomis cyanellus) were the least sensitive to TFM, while ictalurids, black bullhead (Ictalurus melas), channel catfish (Ictalurus punctatus), and tadpole madtom (Notorus gyrinus) were the most sensitive. On-site bioassays conducted before lampricide treatments also revealed that lake sturgeon, channel catfish, and whitefish (Coregonus clupeaformis) were sensitive to the lampricides although considerably less sensitive compared to sea lamprey.
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Dongamanti, Ashok; Aamate, Vikas Kumar; Devulapally, Mohan Gandhi; Gundu, Srinivas; Balabadra, Saikrishna; Manga, Vijjulatha; Yogeeswari, Perumal; Sriram, Dharmarajan; Balasubramanian, Sridhar
2017-11-01
On the basis of reported antimycobacterial property of chroman-4-one pharmacophore, a series of chemically modified bis-spirochromanones were synthesized starting from 2-hydroxyacetophenone and 1,4-dioxaspiro[4.5] decan-8-one using a Kabbe condensation approach. The synthesized bis-spirochromanones were established based on their spectral data and X-ray crystal structure of 6e. All synthesized compounds were evaluated against Mycobacterium tuberculosis H37Rv (ATCC 27294) strain, finding that some products exhibited good antimycobacterial activity with minimum inhibitory concentration as low as [Formula: see text]. Docking studies were carried out to identify the binding interactions of compounds II, 6a and 6n with FtsZ. Compounds exhibiting good in vitro potency in the MTB MIC assay were further evaluated for toxicity using the HEK cell line.
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Tang, Yulin; Li, Shuyan; Qiao, Junlian; Wang, Hongtao; Li, Lei
2013-01-01
Anabaena sp. was used to examine the toxicity of exposure to a nano-TiO2 suspension, Zn2+ solution, and mixtures of nano-TiO2 and Zn2+ suspensions. Typical chlorophyll fluorescence parameters, including effective quantum yield, photosynthetic efficiency and maximal electron transport rate, were measured by a pulse-amplitude modulated fluorometer. Nano-TiO2 particles exhibited no significant toxicity at concentrations lower than 10.0 mg/L. The 96 h concentration for the 50% maximal effect (EC50) of Zn2+ alone to Anabaena sp. was 0.38 ± 0.004 mg/L. The presence of nano-TiO2 at low concentrations (<1.0 mg/L) significantly enhanced the toxicity of Zn2+ and consequently reduced the EC50 value to 0.29 ± 0.003 mg/L. However, the toxicity of the Zn2+/TiO2 system decreased with increasing nano-TiO2 concentration because of the substantial adsorption of Zn2+ by nano-TiO2. The toxicity curve of the Zn2+/TiO2 system as a function of incremental nano-TiO2 concentrations was parabolic. The toxicity significantly increased at the initial stage, reached its maximum, and then decreased with increasing nano-TiO2 concentration. Hydrodynamic sizes, concentration of nano-TiO2 and Zn2+ loaded nano-TiO2 were the main parameters for synergistic toxicity. PMID:23852017
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Kemble, N.E.; Hardesty, D.G.; Ingersoll, C.G.; Johnson, B. Thomas; Dwyer, F.J.; MacDonald, D.D.
2000-01-01
Waukegan Harbor in Illinois was designated as a Great Lakes Area of Concern due to high concentrations of sediment-associated polychlorinated biphenyls (PCBs). The objective of this study was to evaluate the toxicity of 20 sediment samples collected after remediation (primarily dredging) of Waukegan Harbor for PCBs. A 42-day whole sediment toxicity test with the amphipod Hyalella azteca (28-day sediment exposure followed by a 14-day reproductive phase) and sediment toxicity tests with Microtox® were conducted to evaluate sediments from Waukegan Harbor. Endpoints measured were survival, growth, and reproduction (amphipods) and luminescent light emission (bacteria). Survival of amphipods was significantly reduced in 6 of the 20 sediment samples relative to the control. Growth of amphipods (either length or weight) was significantly reduced relative to the control in all samples. However, reproduction of amphipods identified only two samples as toxic relative to the control. The Microtox basic test, conducted with organic extracts of sediments identified only one site as toxic. In contrast, the Microtox solid-phase test identified about 50% of the samples as toxic. A significant negative correlation was observed between reproduction and the concentration of three polynuclear aromatic hydrocarbons (PAHs) normalized to total organic carbon. Sediment chemistry and toxicity data were evaluated using sediment quality guidelines (consensus-based probable effect concentrations, PECs). Results of these analyses indicate that sediment samples from Waukegan Harbor were toxic to H. azteca contaminated at similar contaminant concentrations as sediment samples that were toxic to H. azteca from other areas of the United States. The relationship between PECs and the observed toxicity was not as strong for the Microtox test. The results of this study indicate that the first phase of sediment remediation in Waukegan Harbor successfully lowered concentrations of PCBs at the site. Though the sediments were generally not lethal, there were still sublethal effects of contaminants in sediments at this site observed on amphipods in long-term exposures (associated with elevated concentrations of metals, PCBs, and PAHs).
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Quantifying Synergy: A Systematic Review of Mixture Toxicity Studies within Environmental Toxicology
Cedergreen, Nina
2014-01-01
Cocktail effects and synergistic interactions of chemicals in mixtures are an area of great concern to both the public and regulatory authorities. The main concern is whether some chemicals can enhance the effect of other chemicals, so that they jointly exert a larger effect than predicted. This phenomenon is called synergy. Here we present a review of the scientific literature on three main groups of environmentally relevant chemical toxicants: pesticides, metal ions and antifouling compounds. The aim of the review is to determine 1) the frequency of synergy, 2) the extent of synergy, 3) whether any particular groups or classes of chemicals tend to induce synergy, and 4) which physiological mechanisms might be responsible for this synergy. Synergy is here defined as mixtures with minimum two-fold difference between observed and predicted effect concentrations using Concentration Addition (CA) as a reference model and including both lethal and sub-lethal endpoints. The results showed that synergy occurred in 7%, 3% and 26% of the 194, 21 and 136 binary pesticide, metal and antifoulants mixtures included in the data compilation on frequency. The difference between observed and predicted effect concentrations was rarely more than 10-fold. For pesticides, synergistic mixtures included cholinesterase inhibitors or azole fungicides in 95% of 69 described cases. Both groups of pesticides are known to interfere with metabolic degradation of other xenobiotics. For the four synergistic metal and 47 synergistic antifoulant mixtures the pattern in terms of chemical groups inducing synergy was less clear. Hypotheses in terms of mechanisms governing these interactions are discussed. It was concluded that true synergistic interactions between chemicals are rare and often occur at high concentrations. Addressing the cumulative rather than synergistic effect of co-occurring chemicals, using standard models as CA, is therefore regarded as the most important step in the risk assessment of chemical cocktails. PMID:24794244
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Weston, Donald P; Ding, Yuping; Zhang, Minghua; Lydy, Michael J
2013-01-01
Few currently used agricultural pesticides are routinely monitored for in the environment. Even if concentrations are known, sediment LC(50) values are often lacking for common sediment toxicity testing species. To help fill this data gap, sediments in California's Central Valley were tested for nine hydrophobic pesticides seldom analyzed: abamectin, diazinon, dicofol, fenpropathrin, indoxacarb, methyl parathion, oxyfluorfen, propargite, and pyraclostrobin. Most were detected, but rarely at concentrations acutely toxic to Hyalella azteca or Chironomus dilutus. Only abamectin, fenpropathrin, and methyl parathion were found at concentrations of potential concern, and only in one or two samples. One-quarter of over 100 samples from agriculture-affected waterways exhibited toxicity, and in three-fourths of the toxic samples, pyrethroids exceeded concentrations expected to cause toxicity. The pyrethroid Bi-fen-thrin in particular, as well as lambda-cyhalothrin, cypermethrin, esfenvalerate, permethrin, and the organophosphate chlorpyrifos, were primarily responsible for the observed toxicity, rather than the more novel analytes, despite the fact that much of the sampling targeted areas of greatest use of the novel pesticides. Copyright © 2012 Elsevier Ltd. All rights reserved.
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Different strategies of cadmium detoxification in the submerged macrophyte Ceratophyllum demersum L.
Andresen, Elisa; Mattusch, Jürgen; Wellenreuther, Gerd; Thomas, George; Arroyo Abad, Uriel; Küpper, Hendrik
2013-10-01
The heavy metal cadmium (Cd) is highly toxic to plants. To understand the mechanisms of tolerance and resistance to Cd, we treated the rootless, submerged macrophyte Ceratophyllum demersum L. with sub-micromolar concentrations of Cd under environmentally relevant conditions. X-ray fluorescence measurements revealed changing distribution patterns of Cd and Zn at non-toxic (0.2 nM, 2 nM), moderately toxic (20 nM) and highly toxic (200 nM) levels of Cd. Increasing Cd concentrations led to enhanced sequestration of Cd into non-photosynthetic tissues like epidermis and vein. At toxic Cd concentrations, Zn was redistributed and mainly found in the vein. Cd treatment induced the synthesis of phytochelatins (PCs) in the plants, with a threshold of induction already at 20 nM Cd for PC3. In comparison, in plants treated with Cu, elevated PC levels were detected only at the highest concentrations (100-200 nM Cu). Our results show that also non-accumulators like C. demersum store toxic metals in tissues where the heavy metal interferes least with metabolic pathways, but remaining toxicity interferes with micronutrient distribution. Furthermore, we found that the induction of phytochelatins is not proportional to metal concentration, but has a distinct threshold, specific for each PC species. Finally we could show that 20 nM Cd, which was previously regarded as non-toxic to most plants, already induces detoxifying mechanisms.
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Besinis, Alexandros; De Peralta, Tracy
2014-01-01
Metal-containing nanomaterials have the potential to be used in dentistry for infection control, but little is known about their antibacterial properties. This study investigated the toxicity of silver (Ag), titanium dioxide and silica nanoparticles (NPs) against the oral pathogenic species of Streptococcus mutans, compared to the routine disinfectant, chlorhexidine. The bacteria were assessed using the minimum inhibitory concentration assay for growth, fluorescent staining for live/dead cells, and measurements of lactate. All the assays showed that Ag NPs had the strongest antibacterial activity of the NPs tested, with bacterial growth also being 25-fold lower than that in chlorhexidine. The survival rate of bacteria under the effect of 100 mg l−1 Ag NPs in the media was 2% compared to 60% with chlorhexidine, while the lactate concentration was 0.6 and 4.0 mM, respectively. Silica and titanium dioxide NPs had limited effects. Dialysis experiments showed negligible silver dissolution. Overall, Ag NPs were the best disinfectant and performed better than chlorhexidine. Improvements to the MIC assay are suggested. PMID:23092443
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Comparative toxicity of silver nanoparticles and silver ions to Escherichia coli.
Choi, Yoojin; Kim, Hyun-A; Kim, Kyoung-Woong; Lee, Byung-Tae
2018-04-01
With the increase in silver (Ag)-based products in our lives, it is essential to test the potential toxicity of silver nanoparticles (AgNPs) and silver ions (Ag ions) on living organisms under various conditions. Here, we investigated the toxicity of AgNPs with Ag ions to Escherichia coli K-12 strain under various conditions. We observed that both AgNPs and Ag ions display antibacterial activities, and that Ag ions had higher toxicity to E. coli K-12 strain than AgNPs under the same concentrations. To understand the toxicity of AgNPs at a cellular level, reactive oxygen species (ROS) enzymes were detected for use as antioxidant enzymatic biomarkers. We have also studied the toxicity of AgNPs and Ag ions under various coexistence conditions including: fixed total concentration, with a varied the ratio of AgNPs to Ag ions; fixed the AgNPs concentration and then increased the Ag ions concentration; fixed Ag ions concentration and then increasing the AgNPs concentration. Exposure to AgNPs and Ag ions clearly had synergistic toxicity; however, decreased toxicity (for a fixed AgNPs concentration of 5mg/L, after increasing the Ag ions concentration) to E. coli K-12 strain. AgNPs and Ag ions in the presence of L-cysteine accelerated the bacterial cell growth rate, thereby reducing the bioavailability of Ag ions released from AgNPs under the single and coexistence conditions. Further works are needed to consider this potential for AgNPs and Ag ions toxicity across a range of environmental conditions. As silver nanoparticles (AgNPs)-based products are being broadly used in commercial industries, an ecotoxicological understanding of the AgNPs being released into the environment should be further considered. Here, we investigate the comparative toxicity of AgNPs and silver ions (Ag ions) to Escherichia coli K-12 strain, a representative ecotoxicological bioreporter. This study showed that toxicities of AgNPs and Ag ions to E. coli K-12 strain display different relationships when existing individually or when coexisting, and in the presence of L-cysteine materials. These findings suggest that the toxicology research of nanomaterials should consider conditions when NPs coexist with and without their bioavailable ions. Copyright © 2017. Published by Elsevier B.V.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Suresh, Anil K; Wang, Wei; Pelletier, Dale A
Microorganisms have long been known to develop resistance to metal ions either by sequestering metals inside the cell or by effluxing them into the extracellular media. Here we report the biosynthesis of extracellular silver based single nanocrystallites of well-defined composition and homogeneous morphology utilizing the -proteobacterium, Shewanella oneidensis strain MR-1, upon incubation with an aqueous solution of silver nitrate. Further characterization of these particles revealed that the crystals consist of small, reasonably monodispersed spheres in the size range 2 11 nm (with an average of 4 1.5 nm). The bactericidal effect of these biologically synthesized silver nanoparticles (biogenic-Ag) are comparedmore » to similar chemically synthesized nanoparticles (colloidal silver [colloidal-Ag] and oleate capped silver [oleate-Ag]). The determination of the bactericidal effect of these different silver nanoparticles was assessed using both Gram-negative (E. coli) and Gram-positive (B. subtilis) bacteria and based on the diameter of the inhibition zone in disc diffusion tests, minimum inhibitory concentrations, Live/Dead staining assays, and atomic force microscopy. From a toxicity perspective, a clear synthesis procedure, and a surface coat- and strain-dependent inhibition were observed for silver nanoparticles. Biogenic-Ag was found to be of higher toxicity when compared to colloidal-Ag for both E. coli and B. subtilis. E. coli was found to be more resistant to either of these nanoparticles than B. subtilis. In contrast, Oleate-Ag was not toxic to either of the bacteria. These findings have important implications for the potential uses of Ag nanomaterials and for their fate in biological and environmental systems.« less
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NASA Astrophysics Data System (ADS)
Morales, Andres W.; Zhang, Yu S.; Aleman, Julio; Alerasool, Parissa; Dokmeci, Mehmet R.; Khademhosseini, Ali; Ye, Jing Yong
2016-03-01
Clinical attrition is about 30% from failure of drug candidates due to toxic side effects, increasing the drug development costs significantly and slowing down the drug discovery process. This partly originates from the fact that the animal models do not accurately represent human physiology. Hence there is a clear unmet need for developing drug toxicity assays using human-based models that are complementary to traditional animal models before starting expensive clinical trials. Organ-on-a-chip techniques developed in recent years have generated a variety of human organ models mimicking different human physiological conditions. However, it is extremely challenging to monitor the transient and long-term response of the organ models to drug treatments during drug toxicity tests. First, when an organ-on-a-chip model interacts with drugs, a certain amount of protein molecules may be released into the medium due to certain drug effects, but the amount of the protein molecules is limited, since the organ tissue grown inside microfluidic bioreactors have minimum volume. Second, traditional fluorescence techniques cannot be utilized for real-time monitoring of the concentration of the protein molecules, because the protein molecules are continuously secreted from the tissue and it is practically impossible to achieve fluorescence labeling in the dynamically changing environment. Therefore, direct measurements of the secreted protein molecules with a label-free approach is strongly desired for organs-on-a-chip applications. In this paper, we report the development of a photonic crystal-based biosensor for label-free assays of secreted protein molecules from a liver-on-a-chip model. Ultrahigh detection sensitivity and specificity have been demonstrated.
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Application of in Vitro Biotransformation Data and Pharmacokinetic Modeling to Risk Assessment
The adverse biological effects of toxic substances are dependent upon the exposure concentration and the duration of exposure. Pharmacokinetic models can quantitatively relate the external concentration of a toxicant in the environment to the internal dose of the toxicant in the ...
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Mixture toxicity of wood preservative products in the fish embryo toxicity test.
Coors, Anja; Dobrick, Jan; Möder, Monika; Kehrer, Anja
2012-06-01
Wood preservative products are used globally to protect wood from fungal decay and insects. We investigated the aquatic toxicity of five commercial wood preservative products, the biocidal active substances and some formulation additives contained therein, as well as six generic binary mixtures of the active substances in the fish embryo toxicity test (FET). Median lethal concentrations (LC50) of the single substances, the mixtures, and the products were estimated from concentration-response curves and corrected for concentrations measured in the test medium. The comparison of the experimentally observed mixture toxicity with the toxicity predicted by the concept of concentration addition (CA) showed less than twofold deviation for all binary mixtures of the active substances and for three of the biocidal products. A more than 60-fold underestimation of the toxicity of the fourth product by the CA prediction was detected and could be explained fully by the toxicity of one formulation additive, which had been labeled as a hazardous substance. The reason for the 4.6-fold underestimation of toxicity of the fifth product could not be explained unambiguously. Overall, the FET was found to be a suitable screening tool to verify whether the toxicity of formulated wood preservatives can reliably be predicted by CA. Applied as a quick and simple nonanimal screening test, the FET may support approaches of applying component-based mixture toxicity predictions within the environmental risk assessment of biocidal products, which is required according to European regulations. Copyright © 2012 SETAC.
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Metal-contaminated potato crops and potential human health risk in Bolivian mining highlands.
Garrido, Alan E; Strosnider, William H J; Wilson, Robin Taylor; Condori, Janette; Nairn, Robert W
2017-06-01
This study assessed metals in irrigation water, soil and potato crops impacted by mining discharges, as well as potential human health risk in the high desert near the historic mining center of Potosí, Bolivia. Metal concentrations were compared with international concentration limit guidelines. In addition, an ingested average daily dose and minimum risk level were used to determine the hazard quotient from potato consumption for adults and children. Irrigation water maximum concentrations of Cd, Pb and Zn in mining-impacted sites were elevated 20- to 1100-fold above international concentration limit guidelines. Agricultural soils contained total metal concentrations of As, Cd, Pb and Zn that exceeded concentration limits in agricultural soil guidelines by 22-, 9-, 3- and 12-fold, respectively. Potato tubers in mining-impacted sites had maximum concentrations of As, Cd, Pb and Zn that exceeded concentration limits in commercially sold vegetables by 9-, 10-, 16- and fourfold, respectively. Using conservative assumptions, hazard quotients (HQ) for potatoes alone were elevated for As, Cd and Pb among children (range 1.1-71.8), in nearly all of the mining-impacted areas; and for As and Cd among adults (range 1.2-34.2) in nearly all of the mining-impacted areas. Only one mining-impacted area had a Pb adult HQ for potatoes above 1 for adults. Toxic trace elements in a major regional dietary staple may be a greater concern than previously appreciated. Considering the multitude of other metal exposure routes in this region, it is likely that total HQ values for these metals may be substantially higher than our estimates.
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Mann, L.J.
1989-01-01
Concern has been expressed that some of the approximately 30,900 curies of tritium disposed to the Snake River Plain aquifer from 1952 to 1988 at the INEL (Idaho National Engineering Laboratory) have migrated to springs discharging to the Snake River in the Twin Falls-Hagerman area. To document tritium concentrations in springflow, 17 springs were sampled in November 1988 and 19 springs were sampled in March 1989. Tritium concentrations were less than the minimum detectable concentration of 0.5 pCi/mL (picocuries/mL) in November 1988 and less than the minimum detectable concentration of 0.2 pCi/mL in March 1989; the minimum detectable concentration was smaller in March 1989 owing to a longer counting time in the liquid scintillation system. The maximum contaminant level of tritium in drinking water as established by the U.S. Environmental Protection Agency is 20 pCi/mL. U.S. Environmental Protection Agency sample analyses indicate that the tritium concentration has decreased in the Snake River near Buhl since the 1970's. In 1974-79, tritium concentrations were less than 0.3 +/-0.2 pCi/mL in 3 of 20 samples; in 1983-88, 17 of 23 samples contained less than 0.3 +/-0.2 pCi/mL of tritium; the minimum detectable concentration is 0.2 pCi/mL. On the basis of decreasing tritium concentrations in the Snake River, their correlation to cessation of atmospheric weapons tests tritium concentrations in springflow less than the minimum detectable concentration, and the distribution of tritium in groundwater at the INEL, aqueous disposal of tritium at the INEL has had no measurable effect on tritium concentrations in springflow from the Snake River Plain aquifer and in the Snake River near Buhl. (USGS)
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Sarin, C.; Hall, J.M.; Cotter-Howells, J.
2000-02-01
The toxicity of a heavy metal in solution to a microorganism depends not only on its concentration but also on pH and the concentrations of any aqueous complexing ligands in the microorganism's environment. This paper reports on the use of different inorganic resuscitation media and effect of the chloride ion, Cl{sup {minus}}, on the bioluminescence response of a bacterial biosensor, Escherichia coli HB101 (pUCD607), to four metals: Cd, Cu, Hg, and Pb. The toxicity tests were conducted at pH 4, using 0.1 M KNO{sub 3} as resuscitation medium and adding KCl to investigate effect of Cl{sup {minus}} concentration. The speciesmore » distributions of metals as a function of Cl{sup {minus}} concentration were calculated using GeoChem-PC. Resuscitation in 0.1 M KCl gave significantly higher light output than that in 0.1 M KNO{sub 3}, demonstrating that Cl{sup {minus}} ions increased the toxicity of Hg, apparently because of the formation of HgCl{sub 3}{sup {minus}}, and increased the toxicity of Pb because of PbCl{sup +} formation. The toxicity of Cu decreased at high Cl{sup {minus}} concentrations as free Cu{sup 2+} decreased, in accordance with the free ion model. Concentrations of Cl{sup {minus}} had no significant effect on the toxicity of Cd. This study clearly demonstrates that the chloro-complexes of some heavy metals can be toxic and, for Pb and Hg, more toxic than the free ion.« less
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Huang, Wei Ying; Liu, Fei; Liu, Shu Shen; Ge, Hui Lin; Chen, Hong Han
2011-09-01
The predictions of mixture toxicity for chemicals are commonly based on two models: concentration addition (CA) and independent action (IA). Whether the CA and IA can predict mixture toxicity of phenolic compounds with similar and dissimilar action mechanisms was studied. The mixture toxicity was predicted on the basis of the concentration-response data of individual compounds. Test mixtures at different concentration ratios and concentration levels were designed using two methods. The results showed that the Weibull function fit well with the concentration-response data of all the components and their mixtures, with all relative coefficients (Rs) greater than 0.99 and root mean squared errors (RMSEs) less than 0.04. The predicted values from CA and IA models conformed to observed values of the mixtures. Therefore, it can be concluded that both CA and IA can predict reliable results for the mixture toxicity of the phenolic compounds with similar and dissimilar action mechanisms. Copyright © 2011 Elsevier Inc. All rights reserved.
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Anti-MRSA malleable liposomes carrying chloramphenicol for ameliorating hair follicle targeting
Sung, Calvin T; Weng, Yi-Han; Fang, Jia-You
2017-01-01
Pathogens usually invade hair follicles when skin infection occurs. The accumulated bacteria in follicles are difficult to eradicate. The present study aimed to assess the cutaneous and follicular delivery of chloramphenicol (Cm)-loaded liposomes and the antibacterial activity of these liposomes against methicillin-resistant Staphylococcus aureus (MRSA). Skin permeation was conducted by in vitro Franz diffusion cell. The anti-MRSA potential was checked using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), a well diffusion test, and intracellular MRSA killing. The classic, dimyristoylphosphatidylcholine (DMPC), and deoxycholic acid (DA) liposomes had a vesicle size of 98, 132, and 239 nm, respectively. The incorporation of DMPC or DA into the liposomes increased the bilayer fluidity. The malleable vesicles containing DMPC and DA showed increased follicular Cm uptake over the control solution by 1.5- and 2-fold, respectively. The MIC and MBC of DA liposomes loaded with Cm were 62.5 and 62.5–125 μg/mL, comparable to free Cm. An inhibition zone about 2-fold higher was achieved by DA liposomes as compared to the free control at a Cm dose of 0.5 mg/mL. DA liposomes also augmented antibacterial activity on keratinocyte-infected MRSA. The deformable liposomes had good biocompatibility against keratinocytes and neutrophils (viability >80%). In vivo administration demonstrated that DA liposomes caused negligible toxicity on the skin, based on physiological examination and histology. These data suggest the potential application of malleable liposomes for follicular targeting and the treatment of MRSA-infected dermatologic conditions. PMID:29184410
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Diaz, Dolores, E-mail: diaz.dolores@gene.com; Ford, Kevin A.; Hartley, Dylan P.
Several toxicities are clearly driven by free drug concentrations in plasma, such as toxicities related to on-target exaggerated pharmacology or off-target pharmacological activity associated with receptors, enzymes or ion channels. However, there are examples in which organ toxicities appear to correlate better with total drug concentrations in the target tissues, rather than with free drug concentrations in plasma. Here we present a case study in which a small molecule Met inhibitor, GEN-203, with significant liver and bone marrow toxicity in preclinical species was modified with the intention of increasing the safety margin. GEN-203 is a lipophilic weak base as demonstratedmore » by its physicochemical and structural properties: high LogD (distribution coefficient) (4.3) and high measured pKa (7.45) due to the basic amine (N-ethyl-3-fluoro-4-aminopiperidine). The physicochemical properties of GEN-203 were hypothesized to drive the high distribution of this compound to tissues as evidenced by a moderately-high volume of distribution (Vd > 3 l/kg) in mouse and subsequent toxicities of the compound. Specifically, the basicity of GEN-203 was decreased through addition of a second fluorine in the 3-position of the aminopiperidine to yield GEN-890 (N-ethyl-3,3-difluoro-4-aminopiperidine), which decreased the volume of distribution of the compound in mouse (Vd = 1.0 l/kg), decreased its tissue drug concentrations and led to decreased toxicity in mice. This strategy suggests that when toxicity is driven by tissue drug concentrations, optimization of the physicochemical parameters that drive tissue distribution can result in decreased drug concentrations in tissues, resulting in lower toxicity and improved safety margins. -- Highlights: ► Lower pKa for a small molecule: reduced tissue drug levels and toxicity. ► New analysis tools to assess electrostatic effects and ionization are presented. ► Chemical and PK drivers of toxicity can be leveraged to improve safety.« less
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Ward, Timothy J; Boeri, Robert L; Hogstrand, Christer; Kramer, James R; Lussier, Suzanne M; Stubblefield, William A; Wyskiel, Derek C; Gorsuch, Joseph W
2006-07-01
Tests were conducted with mysids (Americamysis bahia) and silversides (Menidia beryllina) to evaluate the influence of salinity and organic carbon on the chronic toxicity of silver. During 7- and 28-d tests conducted at 10, 20, and 30% per hundred salinity, higher concentrations of dissolved silver generally were required to cause a chronic effect as the salinity of the seawater was increased. The 28-d mysid and silverside 20%-effective concentration values (expressed as dissolved silver) ranged from 3.9 to 60 and from 38 to 170 microg/L, respectively, over the salinity range. This pattern was not observed when the same test results were evaluated against the concentrations of free ionic silver (measured directly during toxicity tests), as predicted by the free-ion activity model. Increasing the concentration of dissolved organic carbon from 1 mg/L to the apparent maximum achievable concentration of 6 mg/L in seawater caused a slight decrease in chronic toxicity to silversides but had no effect on the chronic toxicity to mysids. The possible additive toxicity of silver in both food and water also was investigated. Even at the maximum achievable foodborne concentration, the chronic toxicity of silver added to the water was not affected when silver was also added to the food, based on the most sensitive endpoint (growth). However, although fecundity was unaffected at all five tested concentrations during the test with silver in water only, it was significantly reduced at the two highest waterborne silver concentrations (12 and 24 microg/L) during the test with silver dosed into food and water.
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Karlsson, Kristin; Viklander, Maria; Scholes, Lian; Revitt, Mike
2010-06-15
Sedimentation is a widely used technique in structural best management practices to remove pollutants from stormwater. However, concerns have been expressed about the environmental impacts that may be exerted by the trapped pollutants. This study has concentrated on stormwater ponds and sedimentation tanks and reports on the accumulated metal concentrations (Cd, Cr, Ni, Pb, and Zn) and the associated toxicity to the bacteria Vibrio fischeri. The metal concentrations are compared with guidelines and the toxicity results are assessed in relation to samples for which metal concentrations either exceed or conform to these values. The water phase metal concentrations were highest in the ponds whereas the sedimentation tanks exhibited a distinct decrease towards the outlet. However, none of the water samples demonstrated toxicity even though the concentrations of Cu, Pb, and Zn exceeded the threshold values for the compared guidelines. The facilities with higher traffic intensities had elevated sediment concentrations of Cr, Cu, Ni, and Zn which increased towards the outlet for the sedimentation tanks in agreement with the highest percentage of fine particles. The sediments in both treatment facilities exhibited the expected toxic responses in line with their affinity for heavy metals but the role of organic carbon content is highlighted. Copyright 2010 Elsevier B.V. All rights reserved.
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NASA Astrophysics Data System (ADS)
Levard, C.; Mitra, S.; Badireddy, A.; Jew, A. D.; Brown, G. E.
2011-12-01
Engineered nanomaterials have had an increasing presence in consumer products. Consequently, their release in wastewater systems is believed to pose a viable threat to the environment. NPs are used for drug delivery devices, imaging agents, and consumer products like sunscreens, paints, and cosmetics. Among the major types of manufactured nanoparticles, silver nanoparticles (Ag-NPs) are currently the most widely used in the nanotechnology industry. These particles have unique antibacterial, antiviral, and antifungal properties and as a result, there is a growing concern about the environmental impact of released Ag nanoparticles, particularly their unintended impact on organisms and ecosystems. Even though the toxicity of Ag-NPs has been extensively studied, the environmental transformations that the Ag-NPs may experience once released in the environment have not been considered. These transformations can readily impact their properties and therefore their behavior in terms of reactivity and toxicity. For example, it is known that silver strongly react with Chloride (Cl), which is ubiquitous in natural waters. At a low Cl/Ag ratio, Cl may precipitate on the surface and partly inhibit dissolution. On the contrary, for a high Cl/Ag ratio, chloride may enhance dissolution and therefore toxicity since soluble Ag species are a main source of toxicity. In this context, the focus of this study is on understanding the toxicity of coated Ag-NPs at various concentrations (1ppb-100ppm) on E.Coli (K12) in deionized water and various sodium chloride concentrations that mimic natural conditions (.5, .1 and .01 M NaCl). Ag+ ions (100 ppm-1ppb) were also tested in these salt concentrations as a control. Samples were inoculated in bacteria and incubated for 24 hours. Based on this test, we inferred that increasing concentrations of Ag+ ions/ AgNps played a role in the inhibition of growth of E.Coli K12. A live-dead staining test has shown the correlation between inhibition of growth and toxicity. No significant toxicity was noted until concentrations of 1-10 ppm for Ag+ and 10-100 ppm for AgNPs. In all NaCl concentrations, Ag+ is more toxic than for AgNPs. In addition, we noted that AgNPs in the .5 M of NaCl had the largest toxicity compared to the other salt concentrations and can be explained by the high Cl/Ag ratio. The concentrations for which toxicity has been observed are fewer orders of magnitude higher than the predicted Ag-NPs concentration released in natural waters in the next years.
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Besser, John M.; Brumbaugh, William G.; Papoulias, Diana M.; Ivey, Chris D.; Kunz, James L.; Annis, Mandy; Ingersoll, Christopher G.
2012-01-01
Populations of desert pupfish (Cyprinodon macularius; pupfish), a federally-listed endangered species, inhabit irrigation drains in the Imperial Valley agricultural area of southern California. These drains have varying degrees of selenium (Se) contamination of water, sediment, and aquatic biota. Published Se toxicity studies suggest that these levels of Se contamination may pose risk of chronic toxicity to Se-sensitive fish, but until recently there have been no studies of the chronic toxicity of Se to desert pupfish.A life-cycle Se exposure with pupfish was conducted to estimate dietary and tissue thresholds for toxic effects of Se on all life stages. The dietary exposure was based on live oligochaete worms (Lumbriculus variegatus) dosed with Se by a laboratory food chain based on selenized yeast. Oligochaetes readily accumulated Se from mixtures of selenized and control yeasts. The protocol for dosing oligochaetes for pupfish feeding studies included long-term (at least 28 days) feeding of a low-ration of yeast mixtures to large batches of oligochaetes. Oligochaetes were dosed at five Se levels in a 50-percent dilution series. Pupfish were simultaneously fed Se-dosed oligochaetes and exposed to a series of Se concentrations in water (consisting of 85 percent selenate and 15 percent selenite) to produce exposures that were consistent with Se concentrations and speciation in pupfish habitats. The nutritional characteristics of oligochaete diets were consistent across the range of oligochaete Se concentrations tested.The life-cycle exposure started with laboratory-cultured juvenile pupfish that were exposed to Se through sexual maturation and reproduction (150 days; F0 exposure). The Se exposure continued with eggs, larvae, and juveniles produced by Se-exposed parents (79 days; F1 exposure). Selenium exposure (water and diets), Se bioaccumulation (whole-body and eggs), and toxicity endpoints (juvenile and adult survival and growth; egg production and hatching success, larval survival and deformities) were documented throughout the life-cycle study.Selenium concentrations in water (as much as 52 micrograms per liter [μg/L]) and diets (as much as 53 micrograms per gram [μg/g], on a dry weight basis) bracketed concentrations reported in pupfish habitats. Juvenile F0 pupfish rapidly accumulated Se and bioaccumulation models indicated that pupfish had reached more than 97 percent of maximum whole-body Se concentrations by the time they reached reproductive maturity. Adult pupfish accumulated whole-body Se concentrations that averaged about 40 percent of those in the oligochaete diets. Selenium concentrations in eggs and F1 juveniles were similar to or slightly greater than Se concentrations in F0 adults. Juvenile F0 pupfish contained selenomethionine fractions (62–71 percent of whole-body Se) greater than the average reported for wild pupfish from the Imperial Valley (53 percent).Selenium exposure had minimal effects on survival or growth of juvenile and adult pupfish. There was evidence of toxic effects on pupfish in the highest Se treatment (Se–5), including reduced growth of F0 and F1 juvenile pupfish (17–21 percent less than controls) on some sampling dates. These growth reductions did not persist to subsequent sampling dates, but reduced growth of F1 pupfish in the Se–5 treatment was associated with reduced survival (12 percent less than controls).Egg production was greatest in the controls and decreased with increasing Se exposure, reaching a minimum (51 percent less than controls) in the Se–4 treatment, but egg production was reduced by only 24 percent in the Se–5 treatment, a lesser reduction than in other Se treatments except Se–1. There was no statistically significant overall effect of Se treatment on mean pupfish egg production, reflecting large variation among replicates and among sampling dates. However, comparisons of daily mean egg production for 23 sampling dates indicated that egg production in each of 5 Se treatments was significantly less than controls on multiple (3–7) sampling dates, but no mean for any Se treatment was significantly greater than controls on any date. Significant reductions in daily egg production occurred mainly during the middle of the study and egg production increased in several Se treatments during the final 2 weeks of the study. These results suggest that pupfish egg production, although a highly variable endpoint, was adversely affected by elevated Se exposure.Neither egg hatching success nor survival of F1 larvae indicated clear evidence of Se toxicity. Egg hatching success did not differ significantly among treatments, with means ranging from 84–91 percent. The frequency of morphological deformities (primarily spinal deformities) was greater in larvae 10 days post-fertilization (dpf) from a preliminary reproduction study than in older larvae (14 dpf) from the main reproduction study. The frequency of larval deformities was generally greater in Se treatments than controls, but mean frequencies did not differ significantly among treatments. Survival of F1 larvae to 21 dpf was not reduced significantly by parental Se exposure, but the Se–5 treatment had the lowest larval survival (84 percent), and lowest combined egg hatching and larval survival (76 percent).Results of the Se treatments indicate that pupfish were insensitive to Se toxicity through most of their life cycle. Consistent toxic effects on survival and growth of juvenile and adult pupfish (defined as at least 10 percent reduction compared to controls) occurred only in treatment Se–5, which had a mean dietary Se concentration of 52 μg/g and a mean pupfish whole-body Se concentration of 27 μg/g. These apparent toxicity thresholds for growth and survival rank among the least sensitive chronic Se toxicity values reported for nonreproductive endpoints in freshwater fish. Comparisons of these thresholds to surveys of Se concentrations in the Imperial Valley suggest that risks of Se toxicity are low in pupfish habitats. The dietary threshold was about twice as high as the greatest mean Se concentrations reported in midge larvae from seven sites in the Imperial Valley. Whole-body thresholds were greater than mean whole-body Se concentrations reported for field-collected pupfish from three sites and for the sailfin molly (Poecilia latipinna), a potential bioaccumulation surrogate for pupfish, from seven sites.Reduced egg production, although highly variable, was the most sensitive response of pupfish to Se exposure. Toxic effects on egg production (reductions of 24–51 percent relative to controls) occurred in the four highest Se treatments, corresponding to reproductive toxicity thresholds of 7.3 μg/g for Se in diet, 3.4 μg/g in pupfish (whole body), and 4.4 μg/g in pupfish eggs. These thresholds are substantially lower than published Se toxicity values for reproductive effects in other freshwater fish (for example, 17–24 μg/g in eggs). Reduced egg production has not been reported as a sensitive endpoint in Se toxicity studies, although abnormal ovarian development has been reported in Se-exposed fish, and reduced egg production has been reported as a sensitive response of other Cyprinodon pupfish to other environmental stressors.Selenium concentrations in tissues of pupfish, mollies, and diet items from Imperial Valley sites frequently exceeded concentrations associated with reduced pupfish egg production in the laboratory study. Reduced egg production may limit the ability of pupfish populations to persist and recover in Se-contaminated habitats in the Imperial Valley and elsewhere in their limited range. However, these apparent risks of Se toxicity are not supported by recent surveys of desert pupfish populations in the Imperial Valley. These surveys indicated that desert pupfish made up a small, but variable, component of fish communities in Imperial Valley habitats, including sites with increased levels of Se exposure, and that pupfish distribution and population density indicated no clear relationships with Se concentrations in diets or fish tissues. Additional studies could determine the role of egg production in the maintenance and recovery of desert pupfish populations in Se-contaminated habitats.
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Abouchedid, Rachelle; Hudson, Simon; Thurtle, Natalie; Yamamoto, Takahiro; Ho, James H; Bailey, George; Wood, Michelle; Sadones, Nele; Stove, Christophe P; Dines, Alison; Archer, John R H; Wood, David M; Dargan, Paul I
2017-06-01
Synthetic cannabinoid receptor agonists are the largest group of new psychoactive substances reported in the last decade; in this study we investigated how commonly these drugs are found in patients presenting to the Emergency Department with acute recreational drug toxicity. We conducted an observational cohort study enrolling consecutive adult patients presenting to an Emergency Department (ED) in London (UK) January-July 2015 (6 months) with acute recreational drug toxicity. Residual serum obtained from a serum sample taken as part of routine clinical care was analyzed using high-resolution accurate mass-spectrometry with liquid-chromatography (HRAM-LCMSMS). Minimum clinical data were obtained from ED medical records. 18 (10%) of the 179 patient samples were positive for synthetic cannabinoid receptor agonists. The most common was 5F AKB-48 (13 samples, concentration 50-7600 pg/ml), followed by 5F PB-22 (7, 30-400 pg/mL), MDMB-CHMICA (7, 80-8000 pg/mL), AB-CHMINACA (3, 50-1800 pg/mL), Cumyl 5F-PINACA (1, 800 pg/mL) and BB-22 (1, 60 pg/mL). Only 9/18 (50%) in whom synthetic cannabinoid receptor agonists were detected self-reported synthetic cannabinoid receptor agonist use. The most common clinical features were seizures and agitation, both recorded in four (22%) individuals. Fourteen patients (78%) were discharged from the ED, one of the four admitted to hospital was admitted to critical care. Synthetic cannabinoid receptor agonists were found in 10% of this cohort with acute recreational drug toxicity but self-reported in only half of these. This suggests that presentations to the ED with acute synthetic cannabinoid receptor agonist toxicity may be more common than reported.
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Analysis of Mobile Source Air Toxics (MSATS)–Near-Road VOC and CarbonylConcentrations
This presentation examines data from a year-long study of measured near-road mobile source air toxic (MSAT) concentrations and compares these data with modeled 2005 National Air Toxic Assessment (NATA) results. Field study measurements were collected during a field campaign in ...
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CONCENTRATIONS OF TOXIC AIR POLLUTANTS IN THE U.S. SIMULATED BY AN AIR QUALITY MODEL
As part of the US National Air Toxics Assessment, we have applied the Community Multiscale Air Quality Model, CMAQ, to study the concentrations of twenty gas-phase, toxic, hazardous air pollutants (HAPs) in the atmosphere over the continental United States. We modified the Carbo...
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40 CFR 261.24 - Toxicity characteristic.
Code of Federal Regulations, 2010 CFR
2010-07-01
... the contaminants listed in table 1 at the concentration equal to or greater than the respective value... Hazardous Waste Number specified in Table 1 which corresponds to the toxic contaminant causing it to be hazardous. Table 1—Maximum Concentration of Contaminants for the Toxicity Characteristic EPA HW No. 1...
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Keyes, Mira, E-mail: mkeyes@bccancer.bc.ca; Miller, Stacy; Pickles, Tom
2014-11-01
Purpose: To determine late urinary toxicity (>12 months) in a large cohort of uniformly treated low-dose-rate prostate brachytherapy patients. Methods and Materials: From 1998 to 2009, 2709 patients with National Comprehensive Cancer Network–defined low-risk and low-tier intermediate-risk prostate cancer were treated with Iodine 125 ({sup 125}I) low-dose-rate prostate brachytherapy; 2011 patients with a minimum of 25 months of follow-up were included in the study. Baseline patients, treatment, implant factors, and late urinary toxicity (Radiation Therapy Oncology Group [RTOG] grading system and International Prostate Symptom Score [IPSS]) were recorded prospectively. Time to IPSS resolution, late RTOG genitourinary toxicity was examined with Kaplan-Meier andmore » log-rank tests. Cox proportional hazards regression was done for individual covariates and multivariable models. Results: Median follow-up was 54.5 months (range, 2-13 years). Actuarial toxicity rates reached 27% and 10% (RTOG ≥2 and ≥3, respectively) at 9-13 years. Symptoms resolved quickly in the majority of patients (88% in 6-12 months). The prevalence of RTOG 0, 1, 2, 3, and 4 toxicity with a minimum of 7 years' follow-up was 70%, 21%, 6.4%, 2.3%, and 0.08%, respectively. Patients with a larger prostate volume, higher baseline IPSS, higher D90, acute toxicity, and age >70 years had more late RTOG ≥2 toxicity (all P≤.02). The IPSS resolved slower in patients with lower baseline IPSS and larger ultrasound prostate volume, those not receiving androgen deprivation therapy, and those with higher D90. The crude rate of RTOG 3 toxicity was 6%. Overall the rate of transurethral resection of the prostate was 1.9%; strictures, 2%; incontinence, 1.3%; severe symptoms, 1.8%; late catheterization, 1.3%; and hematuria, 0.8%. The majority (80%) resolved their symptoms in 6-12 months. Conclusion: Long-term urinary toxicity after brachytherapy is low. Although actuarial rates increase with longer follow-up (27% RTOG 2 and 10% RTOG 3 at 13 years), symptoms resolve relatively quickly; between 5 and 13 years' follow-up, >90% of patients have minimal urinary toxicity. Refining patient selection criteria, planning, and treatment delivery may further reduce toxicity.« less
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Classifying environmental pollutants: Part 3. External validation of the classification system.
Verhaar, H J; Solbé, J; Speksnijder, J; van Leeuwen, C J; Hermens, J L
2000-04-01
In order to validate a classification system for the prediction of the toxic effect concentrations of organic environmental pollutants to fish, all available fish acute toxicity data were retrieved from the ECETOC database, a database of quality-evaluated aquatic toxicity measurements created and maintained by the European Centre for the Ecotoxicology and Toxicology of Chemicals. The individual chemicals for which these data were available were classified according to the rulebase under consideration and predictions of effect concentrations or ranges of possible effect concentrations were generated. These predictions were compared to the actual toxicity data retrieved from the database. The results of this comparison show that generally, the classification system provides adequate predictions of either the aquatic toxicity (class 1) or the possible range of toxicity (other classes) of organic compounds. A slight underestimation of effect concentrations occurs for some highly water soluble, reactive chemicals with low log K(ow) values. On the other end of the scale, some compounds that are classified as belonging to a relatively toxic class appear to belong to the so-called baseline toxicity compounds. For some of these, additional classification rules are proposed. Furthermore, some groups of compounds cannot be classified, although they should be amenable to predictions. For these compounds additional research as to class membership and associated prediction rules is proposed.
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Toxicity test of xanthone from mangosteen on zebrafish embryos
NASA Astrophysics Data System (ADS)
Noordin, Muhammad Akram Mohd; Noor, Mahanem Mat; Kamaruddin, Wan Mohd Aizat Wan; Lazim, Azwan Mat; Fazry, Shazrul
2016-11-01
Xanthone is a chemical compound identified in mangosteen pericarp. A previous study showed that xanthone has anti-proliferating effect on cancer cells. In this study we investigate the toxicity level of xanthone in zebrafish embryo to for future reference on other animal model. We employed Fish Embryo Toxicity (FET) assay to determine the toxicity level of different concentrations of xanthone. Embryos were observed at 24, 48 and 72 hours post fertilization (hpf) under microscope at 4× magnification. The extract showed toxicity effect on embryo at concentrations of 250, 125 and 62.5 µg/mL. Concentrations at 15.63, 7.81 and 3.91 µg / mL of xanthone did not harm the embryos and showed 100% of survival.
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Knöbel, Melanie; Busser, Frans J M; Rico-Rico, Angeles; Kramer, Nynke I; Hermens, Joop L M; Hafner, Christoph; Tanneberger, Katrin; Schirmer, Kristin; Scholz, Stefan
2012-09-04
The zebrafish embryo toxicity test has been proposed as an alternative for the acute fish toxicity test, which is required by various regulations for environmental risk assessment of chemicals. We investigated the reliability of the embryo test by probing organic industrial chemicals with a wide range of physicochemical properties, toxicities, and modes of toxic action. Moreover, the relevance of using measured versus nominal (intended) exposure concentrations, inclusion of sublethal endpoints, and different exposure durations for the comparability with reported fish acute toxicity was explored. Our results confirm a very strong correlation of zebrafish embryo to fish acute toxicity. When toxicity values were calculated based on measured exposure concentrations, the slope of the type II regression line was 1 and nearly passed through the origin (1 to 1 correlation). Measured concentrations also explained several apparent outliers. Neither prolonged exposure (up to 120 h) nor consideration of sublethal effects led to a reduced number of outliers. Yet, two types of compounds were less lethal to embryos than to adult fish: a neurotoxic compound acting via sodium channels (permethrin) and a compound requiring metabolic activation (allyl alcohol).
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Gainer, Amy; Cousins, Mark; Hogan, Natacha; Siciliano, Steven D
2018-05-05
Although petroleum hydrocarbons (PHCs) released to the environment typically occur as mixtures, PHC remediation guidelines often reflect individual substance toxicity. It is well documented that groups of aliphatic PHCs act via the same mechanism of action, nonpolar narcosis and, theoretically, concentration addition mixture toxicity principles apply. To assess this theory, ten standardized acute and chronic soil invertebrate toxicity tests on a range of organisms (Eisenia fetida, Lumbricus terrestris, Enchytraeus crypticus, Folsomia candida, Oppia nitens and Hypoaspis aculeifer) were conducted with a refined PHC binary mixture. Reference models for concentration addition and independent action were applied to the mixture toxicity data with consideration of synergism, antagonism and dose level toxicity. Both concentration addition and independent action, without further interactions, provided the best fit with observed response to the mixture. Individual fraction effective concentration values were predicted from optimized, fitted reference models. Concentration addition provided a better estimate than independent action of individual fraction effective concentrations based on comparison with available literature and species trends observed in toxic responses to the mixture. Interspecies differences in standardized laboratory soil invertebrate species responses to PHC contaminated soil was reflected in unique traits. Diets that included soil, large body size, permeable cuticle, low lipid content, lack of ability to molt and no maternal transfer were traits linked to a sensitive survival response to PHC contaminated soil in laboratory tests. Traits linked to sensitive reproduction response in organisms tested were long life spans with small clutch sizes. By deriving single fraction toxicity endpoints considerate of mixtures, we reduce resources and time required in conducting site specific risk assessments for the protection of soil organism's exposure pathway. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
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Patnaik, Rajashree; Padhy, Rabindra N
2018-05-11
Toxicities of methylmercury chloride (CH 3 HgCl) and methylmercury hydroxide (CH 3 HgOH) to cultured neuroblastoma cell line SH-SY5Y in vitro are evaluated. This is the comparative study between two methylmercury compounds to find out the extent of toxicity of these compounds are toxic to SH-SY5Y cell line. Both cytotoxicity and genotoxicity experiments were carried out to find out the more toxic compound. For cytotoxicity study, four staining assay methods independently with trypan blue (TB), acridine orange/ethidium bromide (AO/EB), 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide (MTT), and neutral red (NR) were used and the comet assay method was done for genotoxicity study. The obtained toxicity data were used for probit analysis. In cytotoxicity, CH 3 HgCl had minimum inhibitory concentration (MIC) value in each assay method as 3 mg/L invariably; LC 25 values were in the range 7.41 to 10.23 mg/L, and LC 50 values were 14.79 to 15.48 mg/L; while LC 75 values were 20.89 to 26.91 mg/L. Moreover, LC 100 value was 30 mg/L, known from comet assay experiments for CH 3 HgCl. Similarly for CH 3 HgOH, the MIC value in each assay method was invariably 3 mg/L, the LC 25 values were in the range 12.58 to 16.59 mg/L, and LC 50 values were 19.49 to 23.44 mg/L; LC 75 values were 27.54 to 30.90 mg/L and LC 100 value was 42 mg/L in each assay done for cytotoxicity and genotoxicity studies. Computed DNA fragmentation indices in comet assays were 98.6 ± 0.57 30 mg/L with CH 3 HgCl and 76 ± 5.29 30 mg/L with CH 3 HgOH. This study clearly indicated that methylmercury chloride is more toxic than methylmercury hydroxide to SH-SY5Y cell line. Toxicity of Hg had been quantified with in vitro cultured human neuroblastoma cell line; since it has neurotoxic effects, its neural evaluation has implications in environmental health issues.
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The United States Environmental Protection Agency's (EPA) Office of Ground Water and Drinking Water (OGWDW) has developed a single-laboratory quantitation procedure: the lowest concentration minimum reporting level (LCMRL). The LCMRL is the lowest true concentration for which fu...
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Senn, David; Downing-Kunz, Maureen; Novick, Emily
2016-01-01
Dissolved oxygen (DO) concentration serves as an important indicator of estuarine habitat condition, because all aquatic macro-organisms require some minimum DO level to survive and prosper. The instantaneous DO concentration, measured at a specific location in the water column, results from a balance between multiple processes that add or remove oxygen (Figure 6.1): primary production produces O2; aerobic respiration in the water column and sediments consumes O2; abiotic or microbially-mediated biogeochemical reactions utilize O2 as an oxidant (e.g., oxidation of ammonium, sulfide, and ferrous iron); O2 exchange occurs across the air:water interface in response to under- or oversaturated DO concentrations in the water column; and water currents and turbulent mixing transport DO into and out of zones in the water column. If the oxygen loss rate exceeds the oxygen production or input rate, DO concentration decreases. When DO losses exceed production or input over a prolonged enough period of time, hypoxia ((<2-3 mg/L) or anoxia can develop. Persistent hypoxia or anoxia causes stress or death in aquatic organism populations, or for organisms that can escape a hypoxic or anoxic area, the loss of habitat. In addition, sulfide, which is toxic to aquatic organisms and causes odor problems, escapes from sediments under low oxygen conditions. Low dissolved oxygen is a common aquatic ecosystem response to elevated organic
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Acute toxicity of fire-retardant and foam-suppressant chemicals to yalella azteca (Saussure)
McDonald, Susan F.; Hamilton, Steven J.; Buhl, Kevin J.; Heisinger, James F.
1997-01-01
Acute toxicity tests were conducted with Hyalella azteca Saussure (an amphipod) exposed in soft and hard waters to three fire retardants (Fire-Trol GTS-R, Fire-Trol LCG-R, and Phos-Chek D75-F) and two foam suppressants (Phos-Chek WD-881 and Silv-Ex). The chemicals were slightly to moderately toxic to amphipods. The most toxic chemical to amphipods in soft and hard water was Phos-Chek WD-881 (96-h mean lethal concentration [LC50] equal to 10 mg/L and 22 mg/L, respectively), and the least toxic chemical to amphipods in soft water was Fire-Trol GTS-R (96-h LC50 equal to 127 mg/L) and in hard water was Fire-Trol LCG-R (96-h LC50 equal to 535 mg/L). Concentrations of ammonia in tests with the three fire retardants and both water types were greater than reported LC50 values and probably were the major toxic component. Estimated un-ionized ammonia concentrations near the LC50 were frequently less than the reported LC50 ammonia concentrations for amphipods. The three fire retardants were more toxic in soft water than in hard water even though ammonia and un-ionized ammonia concentrations were higher in hard water tests than in soft water tests. The accidental entry of fire-fighting chemicals into aquatic environments could adversely affect aquatic invertebrates, thereby disrupting ecosystem function.
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Ingersoll, C.G.; MacDonald, D.D.; Brumbaugh, W.G.; Johnson, B. Thomas; Kemble, N.E.; Kunz, J.L.; May, T.W.; Wang, N.; Smith, J.R.; Sparks, D.W.; Ireland, D.S.
2002-01-01
The objective of this study was to evaluate the toxicity of sediments from the Grand Calumet River and Indiana Harbor Canal located in northwestern Indiana, USA. Toxicity tests used in this assessment included 10-day sediment exposures with the amphipod Hyalella azteca, 31-day sediment exposures with the oligochaete Lumbriculus variegatus, and the Microtox® Solid-Phase Sediment Toxicity Test. A total of 30 sampling stations were selected in locations that had limited historic matching toxicity and chemistry data. Toxic effects on amphipod survival were observed in 60% of the samples from the assessment area. Results of a toxicity test with oligochaetes indicated that sediments from the assessment area were too toxic to be used in proposed bioaccumulation testing. Measurement of amphipod length after the 10-day exposures did not provide useful information beyond that provided by the survival endpoint. Seven of the 15 samples that were identified as toxic in the amphipod tests were not identified as toxic in the Microtox test, indicating that the 10-day H. azteca test was more sensitive than the Microtox test. Samples that were toxic tended to have the highest concentrations of metals, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). The toxic samples often had an excess of simultaneously extracted metals (SEM) relative to acid volatile sulfide (AVS) and had multiple exceedances of probable effect concentrations (PECs). Metals may have contributed to the toxicity of samples that had both an excess molar concentration of SEM relative to AVS and elevated concentrations of metals in pore water. However, of the samples that had an excess of SEM relative to AVS, only 38% of these samples had elevated concentration of metals in pore water. The lack of correspondence between SEM-AVS and pore water metals indicates that there are variables in addition to AVS controlling the concentrations of metals in pore water. A mean PEC quotient of 3.4 (based on concentrations of metals, PAHs, and PCBs) was exceeded in 33% of the sediment samples and a mean quotient of 0.63 was exceeded in 70% of the thirty sediment samples from the assessment area. A 50% incidence of toxicity has been previously reported in a database for sediment tests with H. azteca at a mean quotient of 3.4 in 10-day exposures and at a mean quotient of 0.63 in 28-day exposures. Among the Indiana Harbor samples, most of the samples with a mean PEC quotient above 0.63 (i.e., 15 of 21; 71%) and above 3.4 (i.e., 10 of 10; 100%) were toxic to amphipods. Results of this study and previous studies demonstrate that sediments from this assessment area are among the most contaminated and toxic that have ever been reported.
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Toxicity of sediments and pore water from Brunswick Estuary, Georgia
Winger, Parley V.; Lasier, Peter J.; Geitner, Harvey
1993-01-01
A chlor-alkali plant in Brunswick, Georgia, USA, discharged >2 kg mercury/d into a tributary of the Turtle River-Brunswick Estuary from 1966 to 1971. Mercury concentrations in sediments collected in 1989 along the tributary near the chlor-alkali plant ranged from 1 to 27 μg/g (dry weight), with the highest concentrations found in surface (0–8 cm) sediments of subtidal zones in the vicinity of the discharge site. Toxicity screening in 1990 using Microtox® bioassays on pore water extracted on site from sediments collected at six stations distributed along the tributary indicated that pore water was highly toxic near the plant discharge. Ten-day toxicity tests on pore water from subsequent sediment samples collected near the plant discharge confirmed high toxicity to Hyalella azteca, and feeding activity was significantly reduced in whole-sediment tests. In addition to mercury in the sediments, other metals (chromium, lead, and zinc) exceeded 50 μg/g, and polychlorobiphenyl (PCB) concentrations ranged from 67 to 95 μg/g. On a molar basis, acid-volatile sulfide concentrations (20–45 μmol/g) in the sediments exceeded the metal concentrations. Because acid-volatile sulfides bind with cationic metals and form metal sulfides, which are generally not bioavailable, toxicities shown by these sediments were attributed to the high concentrations of PCBs and possibly methylmercury.
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In vitro toxicity testing with microplate cell cultures: Impact of cell binding.
Gülden, Michael; Schreiner, Jeannine; Seibert, Hasso
2015-06-05
In vitro generated data on toxic potencies are generally based on nominal concentrations. However, cellular and extracellular binding and elimination processes may reduce the available free fraction of a compound. Then, nominal effective concentrations do not represent appropriate measures of toxic exposure in vitro and underestimate toxic potencies. In this study it was investigated whether cell binding can affect the availability of chemicals in microplate based toxicity assays. To this end the cytotoxicity of compounds like mercury chloride, digitonin and alcohol ethoxylates, accumulated by cells via different modes, was investigated in 96-well microplate cultures with varying concentrations of Balb/c 3T3 cells. The median effective nominal concentrations of all but one of the tested compounds depended linearly from the cell concentration. Applying a previously developed equilibrium distribution model cell concentration-independent median effective extracellular concentrations and cell burdens, respectively, could be calculated. The compounds were accumulated by the cells with bioconcentration factors, BCF, between 480 and ≥ 25,000. Cell binding of the alcohol ethoxylates was correlated with their lipophilicity. The results show that significant cell binding can occur even at the small cell volume fractions (∼ 1 × 10(-5) to 3 × 10(-3) L/L) encountered in microplate assays. To what extent cell binding affects the bioavailability depends on the BCF and the cell volume fraction. EC50 measurements in the presence of at least two different cell concentrations allow for excluding or detecting significant cell binding and for determining more appropriate measures of toxic exposure in vitro like median effective extracellular (free) concentrations or cell burdens. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
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Besser, John M.; Kubitz, Jody A.; Ingersoll, Chris G.; Braselton, W. Emmett; Giesy, John P.
1995-01-01
Sediment bioassays with larvae of the midge, Chironomus tentans, were used to evaluate influences on the bioavailability and toxicity of copper (Cu) in sediments with a wide range of concentrations of metals, acid-volatile sulfide (AVS), and other physicochemical characteristics. Sediments were collected from sixteen lakes in Michigan, USA, and from twelve sites in the Clark Fork River drainage of Montana, USA, which are contaminated with metals from mining activities and from other anthropogenic sources. Bioassays with C. tentans larvae were conducted for ten days in a static-renewal test system, with endpoints of survival, growth, and metal bioaccumulation. Bioaccumulation of copper (Cu) was strongly correlated with Cu concentrations in porewater, and was increased significantly at Cu concentrations less than those affecting growth or survival. Midge survival and growth were not significantly correlated with concentrations of Cu in sediment or porewater, and were poorly predicted by ratios of acid-extractable metals to AVS in sediments. Principal components analysis indicated that Cu concentrations in porewater and bioaccumulation of Cu by midge larvae were influenced by AVS, sediment organic carbon, and porewater pH, and that toxicity was associated with high concentrations of Cu, high concentrations of zinc (Zn) and ammonia. No toxicity was observed in several sediments which contained low concentrations of AVS and high concentrations of Cu and Zn. In sediments which contain little AVS, bioavailability of metals may be controlled by constituents other than sulfides, such as organic matter and metal hydrous oxides. These results indicate that assessments of toxicity in metal-contaminated sediments should evaluate the importance of metal-binding phases other than sulfides, and the possible contributions of ammonia or other toxicants to toxicity in sediment bioassays.
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Bachl, Jürgen; Oehm, Stefan; Mayr, Judith; Cativiela, Carlos; Marrero-Tellado, José Juan; Díaz Díaz, David
2015-01-01
Phase selective gelation (PSG) of organic phases from their non-miscible mixtures with water was achieved using tetrapeptides bearing a side-chain azobenzene moiety. The presence of the chromophore allowed PSG at the same concentration as the minimum gelation concentration (MGC) necessary to obtain the gels in pure organic phases. Remarkably, the presence of the water phase during PSG did not impact the thermal, mechanical, and morphological properties of the corresponding organogels. In the case of miscible oil/water mixtures, the entire mixture was gelled, resulting in the formation of quasi-hydrogels. Importantly, PSG could be triggered at room temperature by ultrasound treatment of the mixture or by adding ultrasound-aided concentrated solution of the peptide in an oil-phase to a mixture of the same oil and water. Moreover, the PSG was not affected by the presence of salts or impurities existing in water from natural sources. The process could be scaled-up, and the oil phases (e.g., aromatic solvents, gasoline, diesel fuel) recovered almost quantitatively after a simple distillation process, which also allowed the recovery and reuse of the gelator. Finally, these peptidic gelators could be used to quantitatively remove toxic dyes from aqueous solutions. PMID:26006247
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Bharti, Veni; Vasudeva, Neeru; Sharma, Sunil; Duhan, Joginder Singh
2013-01-01
Background: Typhoid fever continues to remain a major public health problem especially in the areas where there is problem of sanitation and hygiene. The emergence of multidrug resistance of Salmonella typhi, the bacteria responsible for Typhoid to ampicillin, chloramphenicol, and cotrimoxazole has further complicated the treatment and management of enteric fever. One strategy for the treatment of the multidrug resistant bacteria is to use herbs in combination with conventional drugs. The present study was done to find out the interaction effect of phenolic, nonphenolic fractions, and volatile oil of Origanum vulgare with ciprofloxacin. Materials and Methods: The minimum inhibitory concentration (MIC) by microdilution method for individual phytoconstituents and in combination with ciprofloxacin was compared for clinically isolated bacteria from patients infected with S. typhi. Fractional inhibitory concentration (FIC) and Fractional inhibitory concentration index (FICI) were also calculated. Results: The MIC declined to a significant level indicating synergistic relationship between ciprofloxacin and phenolic, nonphenolic fractions and volatile oil in vitro. The FICI exhibits synergistic effect for all the three samples while indifferent and antagonistic for samples and for phenolic and nonphenolic fractions. Conclusions: Present study shows that not only the formulation using O. vulgare and ciprofloxacin can overcome multidrug resistance but also will reduce the toxic effects of ciprofloxacin. PMID:24991069
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1-(1H-indol-3-yl)ethanamine derivatives as potent Staphylococcus aureus NorA efflux pump inhibitors.
Hequet, Arnaud; Burchak, Olga N; Jeanty, Matthieu; Guinchard, Xavier; Le Pihive, Emmanuelle; Maigre, Laure; Bouhours, Pascale; Schneider, Dominique; Maurin, Max; Paris, Jean-Marc; Denis, Jean-Noël; Jolivalt, Claude
2014-07-01
The synthesis of 37 1-(1H-indol-3-yl)ethanamine derivatives, including 12 new compounds, was achieved through a series of simple and efficient chemical modifications. These indole derivatives displayed modest or no intrinsic anti-staphylococcal activity. By contrast, several of the compounds restored, in a concentration-dependent manner, the antibacterial activity of ciprofloxacin against Staphylococcus aureus strains that were resistant to fluoroquinolones due to overexpression of the NorA efflux pump. Structure-activity relationships studies revealed that the indolic aldonitrones halogenated at position 5 of the indole core were the most efficient inhibitors of the S. aureus NorA efflux pump. Among the compounds, (Z)-N-benzylidene-2-(tert-butoxycarbonylamino)-1-(5-iodo-1H-indol-3-yl)ethanamine oxide led to a fourfold decrease of the ciprofloxacin minimum inhibitory concentration against the SA-1199B strain when used at a concentration of 0.5 mg L(-1) . To the best of our knowledge, this activity is the highest reported to date for an indolic NorA inhibitor. In addition, a new antibacterial compound, tert-butyl (2-(3-hydroxyureido)-2-(1H-indol-3-yl)ethyl)carbamate, which is not toxic for human cells, was also found. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Ribas, Jonas; Carreño, Ana Maria
2010-01-01
In Brazil, diseases caused by insect bites are frequent. Therefore, it is extremely important that prophylatic measures are adequately carried out, especially in endemic areas such as the Amazon which receives a great number of visitors, for both business and tourism purposes.. To evaluate the use of insect repellents available in the market by military personnel who often go in missions in the middle of the jungle, in the Amazon region. Fifty - one militaries in the Amazon region were selected and they answered a questionnaire in June/2008. 63,7% of the militaries used products that contained Deet in the maximum concentration of only 15% that has minimum repellent action; 36% reported to combine these products with sun protective products which increased the risk of intoxication; 36,4% used a natural repellent during their missions; two of the militaries participants used vitamin B and considered their repellent action ineffective. The repellents that contain Deet and which were used by the group present concentrations that are lower than the concentrations considered safe for using in the jungle. It was frequent the combination of Deet with sun protective products ,which is a potentially toxic association. Natural repellents that have "andiroba" and" copaíba" as components presented a higher perception of protection from the participants.
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Emerging technologies in medical applications of minimum volume vitrification
Zhang, Xiaohui; Catalano, Paolo N; Gurkan, Umut Atakan; Khimji, Imran; Demirci, Utkan
2011-01-01
Cell/tissue biopreservation has broad public health and socio-economic impact affecting millions of lives. Cryopreservation technologies provide an efficient way to preserve cells and tissues targeting the clinic for applications including reproductive medicine and organ transplantation. Among these technologies, vitrification has displayed significant improvement in post-thaw cell viability and function by eliminating harmful effects of ice crystal formation compared to the traditional slow freezing methods. However, high cryoprotectant agent concentrations are required, which induces toxicity and osmotic stress to cells and tissues. It has been shown that vitrification using small sample volumes (i.e., <1 μl) significantly increases cooling rates and hence reduces the required cryoprotectant agent levels. Recently, emerging nano- and micro-scale technologies have shown potential to manipulate picoliter to nanoliter sample sizes. Therefore, the synergistic integration of nanoscale technologies with cryogenics has the potential to improve biopreservation methods. PMID:21955080
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In vitro susceptibility of rabbit strains of Clostridium spiroforme to antimicrobial agents.
Carman, R J; Wilkins, T D
1991-08-30
Using an agar dilution method we measured the minimum inhibitory concentration (MIC) of 12 antimicrobial agents against 11 strains of iota-toxigenic strains of Clostridium spiroforme. Each strain was isolated from a separate outbreak of toxic diarrhoea of rabbits. Vancomycin and bacitracin, both agents used to treat intestinal clostridioses of humans and other animals, had a relatively high MIC (8 micrograms/ml or more). Metronidazole was uniformly active against C. spiroforme. With MIC of 8 micrograms/ml or more, both lincomycin (11 strains) and erythromycin (9 strains) were relatively inactive against C. spiroforme, conversely, penicillin G was active (MIC for 8 strains was 0.5 micrograms/ml or less). Exposure to any one of these drugs has been implicated as a predisposing factor for C. spiroforme mediated diarrhoea of rabbits. The greatest variation in MIC was seen for erythromycin (8-fold), penicillin G (8-fold) and tetracycline (16-fold).
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Antimicrobial and Genotoxicity Effects of Zero-valent Iron Nanoparticles
Barzan, Elham; Mehrabian, Sedigheh; Irian, Saeed
2014-01-01
Background: In a world of nanotechnology, the first concern is the potential environmental impact of nanoparticles. An efficient way to estimate nanotoxicity is to monitor the responses of bacteria exposed to these particles. Objectives: The current study explored the antimicrobial properties of nZVI (zero-valent Iron nanoparticles) on the Gram-negative bacterial systems Erwinia amylovora, Xanthomonas oryzae and the Gram-positive bacterial systems Bacillus cereus and Streptomyces spp. The genotoxicity potential of nZVI was also assayed. Materials and Methods: The toxicity of nZVI was tested by two different methods: Growing bacteria in liquid (broth dilution) and agar media (challenge test) containing different nZVI concentrations for 24-72 hours. The genotoxicity of nZVI was assessed using the preincubation version of the Ames test. Results: The lowest concentrations of nZVI that inhibited the visible growth (MIC) of E. amylovora, X. oryzae, B. cereus and Streptomyces spp. were 625, 550, 1250 and 1280 ppm, respectively. The minimum bactericidal concentration (MBC) for E. amylovora and X. oryzae were 10,000 and 5,000 ppm of nZVI, respectively. MBC was not observed for the Gram positive bacteria. No bacteriostatic and bactericidal effects were observed for oxidized nZVI. Mutant frequency did not increase according to the vehicle control at the concentrations assayed, indicating a lack of mutagenicity associated with nZVI. Conclusions: nZVI nanoparticles are not mutagenic at low concentrations, therefore they can be used without detrimental effects on soil bacteria. PMID:25147712
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Uysal, Y
2013-12-15
The aim of this study was to determine the ability of Lemna minor to remove Cr (VI) ions from wastewater in a continuous flow pond system. This system was used to simulate a wastewater treatment pond and a natural wetland as habitat of plants. In order to find optimal conditions for chromium removal, ponds were operated with aqueous solutions having different pH (4.0-7.0) and chromium concentration of 0.25 mgCr(+6)/L, then plants were exposed to different chromium concentrations (0.25-5.0 mgCr(+6)/L) at pH 4.0. Chromium concentrations, both in biomass and wastewater, were measured and removal efficiency was determined throughout water flow. Growth factors such as growth rates, chlorophyll contents and dry/fresh weight ratios of plants were also determined to measure toxic effects of chromium. The percentages of chromium uptake (PMU) and bioconcentration factors (BCF) were calculated for each run. The highest accumulated chromium concentration (4.423 mgCr/g) was found in plants grown in the first chamber of pond operated at pH 4.0 and 5.0 mgCr/L, while the minimum accumulated chromium concentration (0.122 mgCr/g) was in plants grown in the last chamber of pond operated at pH 4.0 and 0.25 mgCr(+6)/L. Copyright © 2013 Elsevier B.V. All rights reserved.
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Wang, Guifang; Lu, Gang; Zhao, Jiandi; Yin, Pinghe; Zhao, Ling
2016-08-01
Landfill-concentrated leachate from membrane separation processes is a potential pollution source for the surroundings. In this study, the toxicity and estrogenicity potentials of concentrated leachate prior to and during UV-Fenton and Fenton treatments were assessed by a combination of chemical (di (2-ethylhexyl) phthalate and dibutyl phthalate were chosen as targets) and biological (Daphnia magna, Chlorella vulgaris, and E-screen assay) analyses. Removal efficiencies of measured di (2-ethylhexyl) phthalate and dibutyl phthalate were more than 97 % after treatment with the two methods. Biological tests showed acute toxicity effects on D. magna tests in untreated concentrated leachate samples, whereas acute toxicity on C. vulgaris tests was not observed. Both treatment methods were found to be efficient in reducing acute toxicity effects on D. magna tests. The E-screen test showed concentrated leachate had significant estrogenicity, UV-Fenton and Fenton treatment, especially the former, were effective methods for reducing estrogenicity of concentrated leachate. The EEQchem (estradiol equivalent concentration) of all samples could only explain 0.218-5.31 % range of the EEQbio. These results showed that UV-Fenton reagent could be considered as a suitable method for treatment of concentrated leachate, and the importance of the application of an integrated (biological + chemical) analytical approach for a comprehensive evaluation of treatment suitability.
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Losso, Chiara; Novelli, Alessandra Arizzi; De Salvador, Davide; Ghetti, Pier Francesco; Ghirardini, Annamaria Volpi
2010-12-01
Marine and coastal quality assessment, based on test batteries involving a wide array of endpoints, organisms and test matrices, needs for setting up toxicity indices that integrate multiple toxicological measures for decision-making processes and that classify the continuous toxicity response into discrete categories according to the European Water Framework Directive. Two toxicity indices were developed for the lagoon environment such as the Venice Lagoon. Stepwise procedure included: the construction of a database that identified test-matrix pairs (indicators); the selection of a minimum number of ecotoxicological indicators, called toxicological core metrics (CMs-tox) on the basis of specific criteria; the development of toxicity scores for each CM-tox; the integration of the CMs-tox into two indices, the Toxicity Effect Index (TEI), based on the transformation of Toxic Unit (TU) data that were integrated as logarithmic sum, and the Weighted Average Toxicity Index (WATI), starting from toxicity classes integrated as weighted mean. Results from the indices are compared; advantages and drawbacks of both approaches are discussed. Copyright © 2010. Published by Elsevier Ltd.
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Rachitha, P.; Krupashree, K.; Jayashree, G. V.; Gopalan, Natarajan; Khanum, Farhath
2017-01-01
Objective: The aim of this study is to determine the phytochemical composition, antifungal activity of Mentha piperita essential oil (MPE) against Fusarium sporotrichioides. Methods: The phytochemical composition was conducted by gas chromatography mass spectrometry (GC MS) analysis and mycelia growth inhibition was determined by minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC), the morphological characterization was observed by scanning electron microscopy. Finally, the membrane permeability was determined by the release of extracellular constituents, pH, and total lipid content. Result: In GC MS analysis, 22 metabolites were identified such as menthol, l menthone, pulegone, piperitone, caryophyllene, menthol acetate, etc. The antifungal activity against targeted pathogen, with MIC and MFC 500 μg/mL and 1000 μg/mL, respectively. The MPE altered the morphology of F. sporotrichoides hyphae with the loss of cytoplasm content and contorted the mycelia. The increasing concentration of MPE showed increase in membrane permeability of F. sporotrichoides as evidenced by the release of extracellular constituents and pH with the disruption of cell membrane indicating decrease in lipid content of F. sporotrichoides. Conclusion: The observed results showed that MPE exhibited promising new antifungal agent against Fusarium sporotrichioides. SUMMARY F. sporotrichioides, filamentous fungi contaminate to corn and corn--based productsF. sporotrichioides mainly responsible for the production of T-2 toxinPhytochemical composition was conducted by gas chromatography--mass spectrometry analysisMentha piperita essential oil (MPE) is commonly known as peppermintThe F. sporotrichioides growth was inhibited by MPE (minimum inhibitory concentration, minimum fungicidal concentration)Morphological observation by scanning electron microscope. Abbreviations Used: Cfu: Colony forming unit; DMSO: Dimethyl sulfoxide, °C: Degree celsius; F. Sporotrichoides: Fusarium sporotrichioides; EOs: Essential oils; M: Molar, g: Gram/gravity, mg: Milligram; μg: Microgram, ml: Milliliter; mm: Millimeter, min: Minutes; M. piperita: Mentha piperita, MIC: Minimum inhibitory concentration; MFC: Minimum fungicidal concentration; MAE: Mentha arvensis essential oil; Na2SO4: Sodium sulfate; pH: Potential Hydrogen; PDB: Potato Dextrose Broth; SEM: Scanning electron microscope PMID:28250658
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Zhang, Lulu; Van Gestel, Cornelis A M
2017-08-01
The present study aimed to assess the bioavailability and toxicity of lead nitrate and lead chloride to Enchytraeus crypticus in a natural standard soil. Worms were exposed to Pb-spiked soil for 21 d, and survival and reproduction were related to total, 0.01 M CaCl 2 -extractable, and porewater Pb concentrations in the soil and internal concentrations in the surviving animals. The Pb availability for Pb(NO 3 ) 2 and PbCl 2 was similar, as confirmed by Langmuir and Freundlich isotherms. The Pb concentrations in surviving worms increased with increasing Pb concentrations in the soil and did not differ for the 2 Pb salts. Lead was toxic to E. crypticus at median lethal concentrations (LC50s) of 543 and 779 mg Pb/kg dry soil and median effect concentrations (EC50s) of 189 and 134 mg Pb/kg dry soil, for Pb(NO 3 ) 2 and PbCl 2 , respectively. Mortality of E. crypticus was related to internal Pb concentrations in the worms rather than to total or available Pb concentrations in the soil, whereas reproduction toxicity was better explained from Pb concentrations in 0.01 M CaCl 2 extracts or porewater of the test soil than from total Pb concentrations in the soil or Pb concentrations in the worms. Overall, the bioavailability and toxicity of Pb(NO 3 ) 2 and PbCl 2 to E. crypticus in LUFA 2.2 soil did not differ. Environ Toxicol Chem 2017;36:2083-2091. © 2017 SETAC. © 2017 SETAC.
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2017-08-17
the peak serum concentration of TXA when comparing IV and IM administration, IM did reach a minimum concentration which in vitro has been shown to... research is needed to determine the efficacy of TXA given by this route. 200 ::J’ .€ 150 g> .§_ c: 0 1a ...... "E ~ 100 c: 0 u ~ c: ca...serum concentration of TXA when comparing IV and IM administration, IM did reach a minimum concentration which in vitro has been shown to inhibit
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Conference on the Development of Fire-Resistant Aircraft Passenger Seats
NASA Technical Reports Server (NTRS)
Fewell, L. L.; Kourtides, D. A.; Rosser, R. W.; Parker, J. A.
1976-01-01
Papers are presented dealing with the development of aircraft seats with the minimum fire risk. Criteria examined include: flame spread, heat release, and smoke and/or toxic fumes. Materials and performance specifications of all seat material options are provided.
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NASA Astrophysics Data System (ADS)
Liu, Kailin; Xu, Shiji; Zhang, Minghuan; Kou, Yahong; Zhou, Xiaomao; Luo, Kun; Hu, Lifeng; Liu, Xiangying; Liu, Min; Bai, Lianyang
2016-12-01
The toxicity of ionizable organic compounds to organisms depends on the pH, which therefore affects risk assessments of these compounds. However, there is not a direct chemical method to predict the toxicity of ionizable organic compounds. To determine whether hollow-fiber liquid-phase microextraction (HF-LPME) is applicable for this purpose, a three-phase HF-LPME was used to measure sulfadiazine and estimate its toxicity to Daphnia magna in solutions of different pH. The result indicated that the sulfadiazine concentrations measured by HF-LPME decreased with increasing pH, which is consistent with the decreased toxicity. The concentration immobilize 50% of the daphnids (EC50) in 48 h calculated from nominal concentrations increased from 11.93 to 273.5 mg L-1 as the pH increased from 6.0 to 8.5, and the coefficient of variation (CV) of the EC50 values reached 104.6%. When calculated from the concentrations measured by HF-LPME (pH 12 acceptor phase), the EC50 ranged from 223.4 to 394.6 mg L-1, and the CV decreased to 27.60%, suggesting that the concentrations measured by HF-LPME can be used to estimate the toxicity of sulfadiazine irrespective of the solution pH.
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Kreitinger, Joseph P; Quiñones-Rivera, Antonio; Neuhauser, Edward F; Alexander, Martin; Hawthorne, Steven B
2007-09-01
The toxicity and uptake of polycyclic aromatic hydrocarbons (PAHs) by earthworms were measured in soil samples collected from manufactured-gas plant sites having a wide range in PAH concentrations (170-42,000 mg/kg) and soil characteristics. Samples varied from vegetated soils to pure lampblack soot and had total organic carbon contents ranging from 3 to 87%. The biota-soil accumulation factors (BSAFs) observed for individual PAHs in field-collected earthworms (Aporrectodea caliginosa) were up to 50-fold lower than the BSAFs predicted using equilibrium-partitioning theory. Acute toxicity to the earthworm Eisenia fetida was unrelated to total PAH concentration: Mortality was not observed in some soils having high concentrations of total PAHs (>42,000 mg/kg), whereas 100% mortality was observed in other soils having much lower concentrations of total PAHs (1,520 mg/kg). Instead, toxicity appeared to be related to the rapidly released fraction of PAHs determined by mild supercritical CO2 extraction (SFE). The results demonstrate that soils having approximately 16,000 mg rapidly released total PAH/kg organic carbon can be acutely toxic to earthworms and that the concentration of PAHs in soil that is rapidly released by SFE can estimate toxicity to soil invertebrates.
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The acute toxicity of major ion salts to Ceriodaphnia dubia: I. ...
The ions Na+, K+, Ca2+, Mg2+, Cl-, SO42-, and HCO3-/CO32- (referred to as “major ions”) are present in all fresh waters and are physiologically required by aquatic organisms, but can be increased to harmful levels by a variety of anthropogenic activities that speed geochemical weathering or otherwise introduce or concentrate ions. While toxicity of these ions to aquatic organisms has been previously shown, it is also known that their toxicity can vary depending on the concentrations of other co-occurring anions, and understanding these relationships is key to predicting toxicity and establishing appropriate environmental limits. In this paper we conduct a series of experiments with Ceriodaphnia dubia to evaluate the acute toxicity of all twelve major ionsalts (pairing one of the cations with one of the anions) and to determine how toxicity of these salts varies as a function of background water chemistry. All salts except CaSO4 and CaCO3 were acutely toxic to C. dubia below saturation, with the lowest LC50s found for K salts. Of the remaining salts, all but CaCl2 showed some degree of decreased toxicity as the ionic content of the background water increased. Experiments that independently varied Ca:Mg ratio, Na:K ratio, Cl:SO4 ratio, and alkalinity/pH were used to show that Ca concentration was the primary factor influencing the toxicities of Na and Mg salts. In contrast, the toxicities of K salts were primarily influenced by the concentration of Na. Th
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Peck, Mika R; Klessa, David A; Baird, Donald J
2002-04-01
The wetlands of the Magela floodplain of northern Australia, which is the major sink for dissolved metals transported in the Magela Creek system, contain acid-sulfate sediments. The rewetting of oxidized acid-sulfate soil each wet season produces acidic pulses that have the potential to alter the bioavailability of sediment-associated metal contaminants. Acute toxicity tests (72-h mean lethal concentration [LC50]) using the tropical chironomid Chironomus crassiforceps Kieffer showed that copper toxicity decreased from 0.64 mg/L at pH 6 to 2.30 mg/L at pH 4. Uranium toxicity showed a similar trend (36 mg/L at pH 6 and 58 mg/L at pH 4). Sediment toxicity tests developed using C. crassiforceps also showed that both metals were less toxic at the lower sediment pH with pore-water copper toxicity having a lowest-observed-effect concentration of 4.73 mg/L at pH 4 compared to 1.72 mg/L at pH 6. However, a lower pH increased pore-water metal concentrations and overlying water concentrations in bioassays. Hydrogen ion competition on metal receptor sites in C. crassiforceps was proposed to explain the decrease in toxicity in response to increased H+ activity. This study highlights the need to consider site-specific physicochemical conditions before applying generic risk assessment methods.
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A Study on the D. magna and V. fischeri Toxicity Relationship of Industrial Wastewater from Korea
NASA Astrophysics Data System (ADS)
Pyo, S.; Lee, S.; Chun Sang, H.; Park, T. J.; Kim, M. S.
2015-12-01
It is well known that high concentration of TDS (total dissolved solid) in industrial effluent gives rise to the toxicity to the Daphnia magna toxicity test. D. magna is vulnerable to relatively low TDS concentration showing the 24-hr EC50 of Salinity 0.6% (as the sea salt concentration). Recently, standard mandatory toxicity testing using Daphnia magna has been used to monitor industrial effluent toxicity according to Korea standard method (Acute Toxicity Test Method of the Daphnia magna Straus (Cladocera, Crustacea), ES 04704. 1a) under regulation. Since only one acute toxicity testing is applied in the present, we are trying to introduce microbial battery for more complete toxicity assessment. In this study, the acute toxicities between daphnids and microbes were compared. The results of D. magna and Vibrio fischeri toxicity test from 165 industrial wastewater effluents showed high positive correlation. In addition, the possibility of predicting daphnia toxicity from the bacterial toxicity data amounts to 92.6% if we consider salinity effect (>5ppt) together. From this study, we found that the V. fischeri toxicity test is a powerful battery tool to assess the industrial wastewater toxicity. Here, we suggest that luminescent bacteria toxicity test be useful not only for complete toxicity assessment which can't be obtained by daphnia toxicity testing only but also for the reduction cost, time, and labor in the Korean society. Keywords : D. magna, V. fischeri, Industrial waste water, battery test Acknowledgement This research was supported by a grant (15IFIP-B089908-02) from Plant Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government
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2009-05-30
in the polyphenols chlorogenic acid , quinic acid and caffeic acid ). It appears in variable concentrations in urine and at much lower concentrations...liver, kidney, toxicity, gene, expression, nephrotoxin, D-serine, hippuric acid , Puromycin, Amphotericin B 16. SECURITY CLASSIFICATION OF: 17...6 1.4.4. Hippuric Acid
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Toxicity of pyrolysis gases from synthetic polymers
NASA Technical Reports Server (NTRS)
Hilado, C. J.; Soriano, J. A.; Kosola, K. L.; Kourtides, D. A.; Parker, J. A.
1977-01-01
The screening test method was used to investigate toxicity in polyethylene, polystyrene, polymethyl methacrylate, polyaryl sulfone, polyether sulfone, polyphenyl sulfone, and polyphenylene sulfide. Changing from a rising temperature program to a fixed temperature program resulted on shorter times to animal responses. This effect was attributed in part to more rapid generation of toxicants. The toxicants from the sulfur containing polymers appeared to act more rapidly than the toxicants from the other polymers. It was not known whether this effect was due primarily to difference in concentration or in the nature of the toxicants. The carbon monoxide concentration found did not account for the results observed with the sulfur containing polymers. Polyphenyl sulfone appeared to exhibit the least toxicity among the sulfur containing polymers evaluated under these test conditions.
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Carvalho, Indira Valadê; Carnevale, Renata Cavalcanti; Visacri, Marília Berlofa; Mazzola, Priscila Gava; de Fátima Lopes Ambrósio, Rosiane; dos Reis, Marcelo Conrado; de Queiroz, Rachel Alvarenga; Moriel, Patricia
2014-04-01
There are no published reports on pediatric phenytoin toxicity, resulting from the drug interaction between phenytoin and valproic acid. A 12-year-old patient with refractory epilepsy syndrome presented with phenytoin toxicity, following a concomitant treatment with phenytoin, valproic acid, and lamotrigine. The phenytoin concentration detected in the capsules used by the patient was in accordance with the prescribed dose and was appropriate for the age and weight of the patient. However, a supratherapeutic phenytoin serum concentration was observed (21.92 µg phenytoin/mL of blood). Consequently, the phenytoin dose was reduced, and the patient was monitored; 24 hours later the patient did not present with any signs/symptoms of toxicity. Despite the appropriate phenytoin concentration in the capsules, the patient presented with phenytoin toxicity. This toxicity likely resulted from the drug interaction between phenytoin and valproic acid that leads to phenytoin displacement from plasmatic proteins and inhibits phenytoin metabolism, thereby increasing the concentration of free drug in the serum.
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Besser, John M.; Allert, Ann L.; Hardesty, Douglas K.; Ingersoll, Christopher G.; May, Thomas W.; Wang, Ning; Leib, Kenneth J.
2001-01-01
Acid drainage from abandoned mines and from naturally-acidic rocks and soil in the upper Animas River watershed of Colorado generates elevated concentrations of acidity and dissolved metals in stream waters and deposition of metal-contaminated particulates in streambed sediments, resulting in both toxicity and habitat degradation for stream biota. High concentrations of iron (Fe), aluminum (Al), zinc (Zn), copper (Cu), cadmium (Cd), and lead (Pb) occur in acid streams draining headwaters of the upper Animas River watershed, and high concentrations of some metals, especially Zn, persist in circumneutral reaches of the Animas River and Mineral Creek, downstream of mixing zones of acid tributaries. Seasonal variation of metal concentrations is reflected in variation in toxicity of stream water. Loadings of dissolved metals to the upper Animas River and tributaries are greatest during summer, during periods of high stream discharge from snowmelt and monsoonal rains, but adverse effects on stream biota may be greater during winter low-flow periods, when stream flows are dominated by inputs of groundwater and contain greatest concentrations of dissolved metals. Fine stream-bed sediments of the upper Animas River watershed also contain elevated concentrations of potentially toxic metals. Greatest sediment metal concentrations occur in the Animas River upstream from Silverton, where there are extensive deposits of mine and mill tailings, and in mixing zones in the Animas River and lower Mineral Creek, where precipitates of Fe and Al oxides also contain high concentrations of other metals. This report summarizes the findings of a series of toxicity studies in streams of the upper Animas River watershed, conducted on-site and in the laboratory between 1998 and 2000. The objectives of these studies were: (1) to determine the relative toxicity of stream water and fine stream-bed sediments to fish and invertebrates; (2) to determine the seasonal range of toxicity in stream water; (3) to develop site-specific thresholds for toxicity of Zn and Cu in stream water; and (4) to develop models of the contributions of Cu and Zn to toxicity of stream water, which may be used to characterize toxicity before and after planned remediation efforts. We evaluated the toxicity of metal-contaminated sediments by conducting sediment toxicity tests with two species of benthic invertebrates, the midge, Chironomus tentans. and the amphipod, Hyalella azteca. Laboratory toxicity tests with both taxa, exposed to fine stream-bed sediments collected in September 1997, showed some evidence of sediment toxicity, as survival of midge larvae in sediments from Cement Creek (C48) and lower Mineral Creek (M34), and growth of amphipods in sediments from these sites and three Animas River sites (A68, Animas at Silverton; A72, Animas below Silverton, and A73, Animas at Elk Park) were significantly reduced compared to a reference site, South Mineral Creek (SMC) . Amphipods were also exposed to site water and fine stream-bed sediment, separately and in combination, during the late summer low flow period (August-September) of 1998. In these studies, stream water, with no sediment present, from all five sites tested (same sites as above, except C48) caused 90% to 100% mortality of amphipods. In contrast, significant reductions in survival of amphipods occurred at two sites (A72 and SMC) in exposures with field-collected sediment plus stream water, and at only one site (A72) in exposures with sediments and clean overlying water. Concentrations of Zn, Pb, Cu, and Cd were high in both sediment and pore water (interstitial water) from most sites tested, but greatest sediment toxicity was apparently associated with greater concentrations of Fe and/or Al in sediments. These results suggest that fine stream-bed sediments of the more contaminated stream reaches of the upper Animas River watershed are toxic to benthic invertebrates, but that these impacts are less serious than tox
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Mercurio, Philip; Eaglesham, Geoff; Parks, Stephen; Kenway, Matt; Beltran, Victor; Flores, Florita; Mueller, Jochen F; Negri, Andrew P
2018-03-19
The toxicity of herbicide degradation (transformation) products is rarely taken into account, even though these are commonly detected in the marine environment, sometimes at concentrations higher than the parent compounds. Here we assessed the potential contribution of toxicity by transformation products of five photosystem II herbicides to coral symbionts (Symbiodinium sp.), the green algae Dunaliella sp., and prawn (Penaeus monodon) larvae. Concentration-dependent inhibition of photosynthetic efficiency (∆F/F m ') was observed for all herbicides in both microalgal species. The toxicity of solutions of aged diuron solutions containing transformation products to Symbiodinium sp. and Dunaliella sp. was greater than could be explained by the concentrations of diuron measured, indicating transformation products contributed to the inhibition of ∆F/F m '. However, the toxicity of aged atrazine, simazine, hexazinone, and ametryn solutions could be explained by the concentration of parent herbicide, indicating no contribution by transformation products. Prawn larval metamorphosis was not sensitive to the herbicides, but preliminary results indicated some toxicity of the transformation products of atrazine and diuron. Risk assessments should take into account the contribution of herbicide transformation products; however, further studies are clearly needed to test the toxicity of a far wider range of transformation products to a representative diversity of relevant taxa.
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Antibacterial, antifungal and cytotoxic evaluation of some new quinazolinone derivatives
Hassanzadeh, F.; Jafari, E.; Hakimelahi, G.H.; Khajouei, M. Rahmani; Jalali, M.; Khodarahmi, G.A.
2012-01-01
Quinazolinone ring system is renown because of its wide spectrum of pharmacological activities due to various substitutions on this ring system. In this study, the minimum inhibitory concentration of the synthesized compounds in our laboratory was determined by micro dilution Alamar Blue® Assay against six strains of bacteria (three Gram-positive and three Gram-negative) and three strains of fungi. Following a broth micro dilution minimum inhibitory concentration (MIC) test, Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC) tests were performed. Cytotoxic effects of the compounds were measured using the MTT colorimetric assay on HeLa cell line. Results of antimicrobial screening showed that compounds had better bacteriostatic activity against Gram-negative bacteria. Results from MBC revealed that these compounds had more significant bacteriostatic than bactericidal activities. Nearly all screened compounds showed good activity against C. albicans and A. niger. Results from MFC indicated that these compounds had better fungistatic rather than fungicidal activities. The synthesized target molecules were found to exhibit different cytotoxicity in the range of 10 to 100 μM on HeLa cell line. Compounds 6 and 7 exhibited acceptable cytotoxicity approximately 50% at 10 μM concentration. PMID:23181085
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Reddy, M Vikram; Satpathy, Deepmala; Dhiviya, K Shyamala
2013-08-01
The concentrations of toxic heavy metals-Cd and Pb and micronutrients-Cu, Mn, and Zn were assessed in the surface soil and water of three different stages of paddy (Oryza sativa L.) fields, the stage I-the first stage in the field soon after transplantation of the paddy seedlings, holding adequate amount of water on soil surface, stage II-the middle stage with paddy plants of stem of about 40 cm length, with sufficient amount of water on the soil surface, and stage III-the final stage with fully grown rice plants and very little amount of water in the field at Bahour, a predominantly paddy cultivating area in Puducherry located on the southeast Coast of India. Comparison of the heavy metal and micronutrient concentrations of the soil and water across the three stages of paddy field showed their concentrations were significantly higher in soil compared with that of water (p < 0.05) of the fields probably because of accumulation and adsorption in soil. The elemental concentrations in paddy soil as well as water was in the ranking order of Cd > Mn > Zn > Cu > Pb indicating concentration of Cd was maximum and Pb was minimum. The elemental concentrations in both soil and water across the three stages showed a ranking order of stage II > stage III > stage I. The runoff from the paddy fields has affected the elemental concentrations of the water and sediment of an adjacent receiving rivulet.
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[Determination of sensitivity of biofilm-positive forms of microorganisms to antibiotics].
Holá, Veronika; Růzicka, Filip; Tejkalová, Renata; Votava, Miroslav
2004-10-01
Nosocomial infections caused by biofilm-positive microorganisms are a serious therapeutic problem. In the biofilm, microorganisms are protected against adverse effects of the external environment, including the action of antibiotics. It is well known that the values of minimum inhibitory concentrations (MIC) determined for planktonic forms do not correspond to the actual concentrations of antibiotics necessary for the eradication of bacteria in a biofilm. The purpose of the study was to propose a method of determining minimum biofilm inhibitory concentrations (MBIC) and minimum biofilm eradication concentrations (MBEC) and to compare these values with MIC values. Biofilm-positive strains of Staphylococcus epidermidis were cultured so as to form a biofilm layer on polystyrene pegs. The biofilm on the pegs was then exposed to the action of antibiotics and after 18 hours we determined the minimum biofilm inhibitory concentration (MBIC). The evaluation of minimum biofilm eradication concentrations was done colorimetrically from the metabolic activity of surviving cells. MBIC and MBEC values were many times higher than MIC values. We selected such a duration of the biofilms cultivation on the pegs of the plate, which ensured that the number of bacterial cells corresponded to standard MIC assessment. The MBEC values established in our study indicate that the currently used concentrations of tested antibiotics cannot be used in monotherapy for an efficacious eradication of a biofilm. The MBEC determination is a far more laborious and time-consuming method than the determination of MIC, but the use of plates with pegs facilitates the handling of biofilms. The advantage of our method is the possibility of standardization of the size of the inoculum and thus of the whole MBEC assessment.
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Effect of heating rate on toxicity of pyrolysis gases from some synthetic polymers
NASA Technical Reports Server (NTRS)
Hilado, C. J.; Soriano, J. A.; Kosola, K. L.
1977-01-01
The effect of heating rate on the toxicity of the pyrolysis gases from some synthetic polymers was investigate, using a screening test method. The synthetic polymers were polyethylene, polystyrene, polymethyl methacrylate, polycarbonate, ABS, polyaryl sulfone, polyether sulfone, and polyphenylene sulfide. The toxicants from the sulfur-containing polymers appeared to act more rapidly than the toxicants from the other polymers. It is not known whether this effect is due primarily to differences in concentration or in the nature of the toxicants. The carbon monoxide concentrations found do not account for the observed results.
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NASA Astrophysics Data System (ADS)
Uria-Tellaetxe, Iratxe; Navazo, Marino; de Blas, Maite; Durana, Nieves; Alonso, Lucio; Iza, Jon
2016-04-01
Despite the toxicity of naphthalene and the fact that it is a precursor of atmospheric photooxidants and secondary aerosol, studies on ambient gas-phase naphthalene are generally scarce. Moreover, as far as we are concerned, this is the first published one using long-term hourly ambient gas-phase naphthalene concentrations. In this work, it has been also demonstrated the usefulness of ambient gas-phase naphthalene to identify major sources of volatile organic compounds (VOC) in complex scenarios. Initially, in order to identify main benzene emission sources, hourly ambient measurements of 60 VOC were taken during a complete year together with meteorological data in an urban/industrial area. Later, due to the observed co-linearity of some of the emissions, a procedure was developed to recover naphthalene concentration data from recorded chromatograms to use it as a tracer of the combustion and distillation of petroleum products. The characteristic retention time of this compound was determined comparing previous GC-MS and GC-FID simultaneous analysis by means of relative retention times, and its concentration was calculated by using relative response factors. The obtained naphthalene concentrations correlated fairly well with ethene (r = 0.86) and benzene (r = 0.92). Besides, the analysis of daily time series showed that these compounds followed a similar pattern, very different from that of other VOC, with minimum concentrations at day-time. This, together with the results from the assessment of the meteorological dependence pointed out a coke oven as the major naphthalene and benzene emitting sources in the study area.
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Giesen, Daniel; van Gestel, Cornelis A M
2013-03-01
Quantitative structure-activity relationships (QSARs) are an established tool in environmental risk assessment and a valuable alternative to the exhaustive use of test animals under REACH. In this study a QSAR was developed for the toxicity of a series of six chloroanilines to the soil-dwelling collembolan Folsomia candida in standardized natural LUFA2.2 soil. Toxicity endpoints incorporated in the QSAR were the concentrations causing 10% (EC10) and 50% (EC50) reduction in reproduction of F. candida. Toxicity was based on concentrations in interstitial water estimated from nominal concentrations in the soil and published soil-water partition coefficients. Estimated effect concentrations were negatively correlated with the lipophilicity of the compounds. Interstitial water concentrations for both the EC10 and EC50 for four compounds were determined by using solid-phase microextraction (SPME). Measured and estimated concentrations were comparable only for tetra- and pentachloroaniline. With decreasing chlorination the disparity between modelled and actual concentrations increased. Optimisation of the QSAR therefore could not be accomplished, showing the necessity to move from total soil to (bio)available concentration measurements. Copyright © 2012 Elsevier Ltd. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Kaetsu, I.; Ito, A.; Hayashi, K.
1973-06-01
The effect of homogeneity of polymerization phase and monomer concentration on the temperature dependence of initial polymerization rate was studied in the radiation-induced radical polymerization of binary systems consisting of glass-forming monomer and solvent. In the polymerization of a completely homogeneous system such as HEMA-propylene glycol, a maximum and a minimum in polymerization rates as a function of temperature, characteristic of the polymerization in glass-forming systems, were observed for all monomer concentrations. However, in the heterogeneous polymerization systems such as HEMA-triacetin and HEMAisoamyl acetate, maximum and minimum rates were observed in monomer-rich compositions but not at low monomer concentrations. Furthermore,more » in the HEMA-dioctyl phthalate polymerization system, which is extremely heterogeneous, no maximum and minimum rates were observed at any monomer concentration. The effect of conversion on the temperature dependence of polymerization rate in homogeneous bulk polymerization of HEMA and GMA was investigated. Maximum and minimum rates were observed clearly in conversions less than 10% in the case of HEMA and less than 50% in the case of GMA, but the maximum and minimum changed to a mere inflection in the curve at higher conversions. A similar effect of polymer concentration on the temperature dependence of polymerization rate in the GMA-poly(methyl methacrylate) system was also observed. It is deduced that the change in temperature dependence of polymerization rate is attributed to the decrease in contribution of mutual termination reaction of growing chain radicals to the polymerization rate. (auth)« less
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Efficient synthesis of new 2,3-dihydrooxazole-spirooxindoles hybrids as antimicrobial agents.
Tiwari, Shailendra; Pathak, Poonam; Sagar, Ram
2016-05-15
Two series of new 2,3-dihydrooxazole-spirooxindole derivatives were efficiently synthesized starting from N'-(2-oxoindolin-3-ylidene) benzohydrazide/N'-(2-oxoindolin-3-ylidene)-2-phenoxyacetohydrazide using designed synthetic route. Newly synthesized 2,3-dihydrooxazole-spirooxindole derivatives were screened for their antibacterial and antifungal activity against different pathogenic strain of bacteria and fungi. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) were determined for the test compounds as well as for reference standards. Compounds 4e, 4g, 7g have shown good antibacterial activity whereas compounds 4f, 7b, 7d have displayed better antifungal activity. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Willis, Alison M; Oris, James T
2014-09-01
The present study examined photo-induced toxicity and toxicokinetics for acute exposure to selected polycyclic aromatic hydrocarbons (PAHs) in zebrafish. Photo-enhanced toxicity from co-exposure to ultraviolet (UV) radiation and PAHs enhanced the toxicity and exhibited toxic effects at PAH concentrations orders of magnitude below effects observed in the absence of UV. Because environmental exposure to PAHs is usually in the form of complex mixtures, the present study examined the photo-induced toxicity of both single compounds and mixtures of PAHs. In a sensitive larval life stage of zebrafish, acute photo-induced median lethal concentrations (LC50s) were derived for 4 PAHs (anthracene, pyrene, carbazole, and phenanthrene) to examine the hypothesis that phototoxic (anthracene and pyrene) and nonphototoxic (carbazole and phenanthrene) pathways of mixtures could be predicted from single exposures. Anthracene and pyrene were phototoxic as predicted; however, carbazole exhibited moderate photo-induced toxicity and phenanthrene exhibited weak photo-induced toxicity. The toxicity of each chemical alone was used to compare the toxicity of mixtures in binary, tertiary, and quaternary combinations of these PAHs, and a predictive model for environmental mixtures was generated. The results indicated that the acute toxicity of PAH mixtures was additive in phototoxic scenarios, regardless of the magnitude of photo-enhancement. Based on PAH concentrations found in water and circumstances of high UV dose to aquatic systems, there exists potential risk of photo-induced toxicity to aquatic organisms. © 2014 SETAC.
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Oil and oil dispersant do not cause synergistic toxicity to fish embryos.
Adams, Julie; Sweezey, Michael; Hodson, Peter V
2014-01-01
Atlantic herring (Clupea harengus) embryos were exposed to water accommodated fractions (WAFs; oil dissolved in water) and chemically enhanced water accommodated fractions (CEWAFs; oil dispersed in water with Corexit 9500A) of Medium South American (MESA) crude oil. The CEWAF was approximately 100-fold more toxic than WAF based on nominal loadings of test solutions (% v/v). In contrast, the ratio of WAF and CEWAF toxicity expressed as measured oil concentrations approximated 1.0, indicating that the higher toxicity of CEWAFs was caused by an increase in exposure to hydrocarbons with chemical dispersion. In a second experiment, the chronic toxicity of Corexit 9500A and chemically dispersed heavy fuel oil 7102 (HFO 7102) to rainbow trout (Oncorhynchus mykiss) embryos was compared to chemically dispersed Nujol, a nontoxic mineral oil. Dispersant alone was toxic, but caused different signs of toxicity than HFO 7102. Nujol at a dispersant-to-oil ratio of 1:20 was nontoxic, suggesting that dispersant was sequestered by oil and not present at toxic concentrations. In contrast, the same nominal loadings of dispersed HFO 7102 caused concentration-dependent increases in toxicity. Both experiments suggest that chemically dispersed oil was more toxic to fish embryos than solutions created by mechanical mixing due to the increased exposure of fish to petroleum hydrocarbons and not to changes in hydrocarbon toxicity. The Nujol control discriminated between the toxicity of oil and chemical dispersant and would be a practical addition to programs of dispersant testing.
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Zhang, Xu; Jin, Weiqi; Li, Jiakun; Wang, Xia; Li, Shuo
2017-04-01
Thermal imaging technology is an effective means of detecting hazardous gas leaks. Much attention has been paid to evaluation of the performance of gas leak infrared imaging detection systems due to several potential applications. The minimum resolvable temperature difference (MRTD) and the minimum detectable temperature difference (MDTD) are commonly used as the main indicators of thermal imaging system performance. This paper establishes a minimum detectable gas concentration (MDGC) performance evaluation model based on the definition and derivation of MDTD. We proposed the direct calculation and equivalent calculation method of MDGC based on the MDTD measurement system. We build an experimental MDGC measurement system, which indicates the MDGC model can describe the detection performance of a thermal imaging system to typical gases. The direct calculation, equivalent calculation, and direct measurement results are consistent. The MDGC and the minimum resolvable gas concentration (MRGC) model can effectively describe the performance of "detection" and "spatial detail resolution" of thermal imaging systems to gas leak, respectively, and constitute the main performance indicators of gas leak detection systems.
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Vuorinen, Pekka J; Kiviranta, Hannu; Koistinen, Jaana; Pöyhönen, Outi; Ikonen, Erkki; Keinänen, Marja
2014-01-15
Changes in the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Baltic salmon muscle were studied during the spawning migration from the southern Baltic Sea to rivers flowing into the northern Gulf of Bothnia and during the spawning period. The aim was to obtain information to facilitate the arrangement of salmon fisheries such that the human dioxin intake is taken into account. The EC maximum allowable total toxic equivalent concentration (WHO-TEQPCDD/F+PCB) was exceeded in the muscle of the majority of the migrating salmon, except in the Baltic Proper. The fresh-weight-based concentrations of all toxicant groups in salmon tended to be the lowest in the Baltic Proper and the Northern Quark, and all toxicant concentrations, except PCDDs and PCDFs, were significantly higher in the spawning salmon than in the salmon caught during the spawning run. The fat content of the salmon muscle decreased by 60% during the spawning run, and the lipid-based total toxicant concentrations were consequently 4.2-6.2 times higher during the spawning period than during the spawning migration. However, the toxicants were concentrated just before spawning, and thus there is no essential difference related to whether the salmon are caught in the sea or the recreational river fishery. © 2013.
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Besser, J.M.; Brumbaugh, W.G.; Kemble, N.E.; May, T.W.; Ingersoll, C.G.
2004-01-01
We evaluated the influence of sediment characteristics, acid-volatile sulfide (AVS) and organic matter (OM), on the toxicity of chromium (Cr) in freshwater sediments. We conducted chronic (28-42-d) toxicity tests with the amphipod Hyalella azteca exposed to Cr(VI) and Cr(III) in water and in spiked sediments. Waterborne Cr(VI) caused reduced survival of amphipods with a median lethal concentration (LC50) of 40 ??g/L. Cr(VI) spiked into test sediments with differing levels of AVS resulted in graded decreases in AVS and sediment OM. Only Cr(VI)-spiked sediments with low AVS concentrations (<1 ??mol/g) caused significant amphipod mortality. Waterborne Cr(III) concentrations near solubility limits caused decreased survival of amphipods at pH 7 and pH 8 but not at pH 6. Sediments spiked with high levels of Cr(III) did not affect amphipod survival but had minor effects on growth and inconsistent effects on reproduction. Pore waters of some Cr(III)-spiked sediments contained measurable concentrations of Cr(VI), but observed toxic effects did not correspond closely to Cr concentrations in sediment or pore waters. Our results indicate that risks of Cr toxicity are low in freshwater sediments containing substantial concentrations of AVS.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Dutton, Spencer M.; Fisk, William J.
For a stand-alone retail building, a primary school, and a secondary school in each of the 16 California climate zones, the EnergyPlus building energy simulation model was used to estimate how minimum mechanical ventilation rates (VRs) affect energy use and indoor air concentrations of an indoor-generated contaminant. The modeling indicates large changes in heating energy use, but only moderate changes in total building energy use, as minimum VRs in the retail building are changed. For example, predicted state-wide heating energy consumption in the retail building decreases by more than 50% and total building energy consumption decreases by approximately 10% asmore » the minimum VR decreases from the Title 24 requirement to no mechanical ventilation. The primary and secondary schools have notably higher internal heat gains than in the retail building models, resulting in significantly reduced demand for heating. The school heating energy use was correspondingly less sensitive to changes in the minimum VR. The modeling indicates that minimum VRs influence HVAC energy and total energy use in schools by only a few percent. For both the retail building and the school buildings, minimum VRs substantially affected the predicted annual-average indoor concentrations of an indoor generated contaminant, with larger effects in schools. The shape of the curves relating contaminant concentrations with VRs illustrate the importance of avoiding particularly low VRs.« less
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Quinn, Brian; Schmidt, Wiebke; O'Rourke, Kathleen; Hernan, Robert
2011-07-01
Pharmaceuticals, including the lipid regulator gemfibrozil and the non-steroidal anti-inflammatory drug diclofenac have been identified in waste water treatment plant effluents and receiving waters throughout the western world. The acute and chronic toxicity of these compounds was assessed for three freshwater species (Daphnia magna, Pseudokirchneriella subcapitata, Lemna minor) using standardised toxicity tests with toxicity found in the non-environmentally relevant mid mg L(-1) concentration range. For the acute endpoints (IC(50) and EC(50)) gemfibrozil showed higher toxicity ranging from 29 to 59 mg L(-1) (diclofenac 47-67 mg L(-1)), while diclofenac was more toxic for the chronic D. magna 21 d endpoints ranging from 10 to 56 mg L(-1) (gemfibrozil 32-100 mg L(-1)). These results were compared with the expression of several biomarkers in the zebra mussel (Dreissena polymorpha) 24 and 96 h after exposure by injection to concentrations of 21 and 21,000 μg L(-1) corresponding to nominal concentrations of 1 and 1000 μg L(-1). Exposure to gemfibrozil and diclofenac at both concentrations significantly increased the level of lipid peroxidation, a biomarker of damage. At the elevated nominal concentration of 1000 μg L(-1) the biomarkers of defence glutathione transferase and metallothionein were significantly elevated for gemfibrozil and diclofenac respectively, as was DNA damage after 96 h exposure to gemfibrozil. No evidence of endocrine disruption was observed using the alkali-labile phosphate technique. Results from this suite of biomarkers indicate these compounds can cause significant stress at environmentally relevant concentrations acting primarily through oxidation pathways with significant destabilization of the lysosomal membrane and that biomarker expression is a more sensitive endpoint than standardised toxicity tests. Copyright © 2011 Elsevier Ltd. All rights reserved.
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Romero-Freire, A; Peinado, F J Martín; Ortiz, M Díez; van Gestel, C A M
2015-10-01
This study aimed at assessing the influence of soil properties on the uptake and toxicity effects of arsenic in the earthworm Eisenia andrei exposed for 4 weeks to seven natural soils spiked with different arsenic concentrations. Water-soluble soil concentrations (AsW) and internal As concentrations in the earthworms (AsE) were greatly different between soils. These two variables were highly correlated and were key factors in earthworm toxicity response. AsW was explained by some soil properties, such as the pH, calcium carbonate content, ionic strength, texture or oxide forms. Toxicity showed a clear variation between soils, in some cases without achieving 50 % adverse effect at the highest As concentration added (600 mg kg(-1)). Nevertheless, soil properties did not show, in general, a high relation with studied toxicity endpoints, although the high correlation with AsW could greatly reduce indirectly As bioavailability and toxicity risk for earthworms. Obtained results suggest that soil properties should be part of the criteria to establishing thresholds for contaminated soils because they will be key in controlling As availability and thus result in different degrees of toxicity.
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NASA Astrophysics Data System (ADS)
Zeb, BibiSaima; Ping, Zheng; Mahmood, Qaisar; Lin, Qiu; Pervez, Arshid; Irshad, Muhammad; Bilal, Muhammad; Bhatti, Zulfiqar Ahmad; Shaheen, Shahida
2017-07-01
This research work is focusing on the toxicities of heavy metals of industrial origin to anaerobic digestion of the industrial wastewater. Photobacterium phosphoreum T3S was used as an indicator organism. The acute toxicities of heavy metals on P. phosphoreum T3S were assessed during 15-min half inhibitory concentration (IC50) as indicator at pH 5.5-6. Toxicity assays involved the assessment of multicomponent mixtures using TU and MTI approaches. The results of individual toxicity indicated that the toxicity of Cd, Cu and Pb on P. phosphoreum increased with increasing concentrations and there was a linear correlation. The 15-min IC50 values of Cd, Cu and Pb were 0.537, 1.905 and 1.231 mg/L, respectively, and their toxic order was Cd > Pb > Cu. The combined effects of Cd, Cu and Pb were assayed by equivalent concentration mixing method. The results showed that the combined effects of Cd + Cu, Cd + Pb, Cu + Pb, Cd + Cu + Pb were antagonistic, antagonistic and partly additive. The combined effect of three heavy metals was partly additive.
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Influence of flow-through and renewal exposures on the toxicity of copper to rainbow trout
Welsh, P.G.; Lipton, J.; Mebane, C.A.; Marr, J.C.A.
2008-01-01
We examined changes in water chemistry and copper (Cu) toxicity in three paired renewal and flow-through acute bioassays with rainbow trout (Oncorhynchus mykiss). Test exposure methodology influenced both exposure water chemistry and measured Cu toxicity. Ammonia and organic carbon concentrations were higher and the fraction of dissolved Cu lower in renewal tests than in paired flow-through tests. Cu toxicity was also lower in renewal tests; 96 h dissolved Cu LC50 values were 7-60% higher than LC50s from matching flow-through tests. LC50 values in both types of tests were related to dissolved organic carbon (DOC) concentrations in exposure tanks. Increases in organic carbon concentrations in renewal tests were associated with reduced Cu toxicity, likely as a result of the lower bioavailability of Cu-organic carbon complexes. The biotic ligand model of acute Cu toxicity tended to underpredict toxicity in the presence of DOC. Model fits between predicted and observed toxicity were improved by assuming that only 50% of the measured DOC was reactive, and that this reactive fraction was present as fulvic acid. ?? 2007 Elsevier Inc. All rights reserved.
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Peters, Adam; Lofts, Stephen; Merrington, Graham; Brown, Bruce; Stubblefield, William; Harlow, Keven
2011-11-01
Ecotoxicity tests were performed with fish, invertebrates, and algae to investigate the effect of water quality parameters on Mn toxicity. Models were developed to describe the effects of Mn as a function of water quality. Calcium (Ca) has a protective effect on Mn toxicity for both fish and invertebrates, and magnesium (Mg) also provides a protective effect for invertebrates. Protons have a protective effect on Mn toxicity to algae. The models derived are consistent with models of the toxicity of other metals to aquatic organisms in that divalent cations can act as competitors to Mn toxicity in fish and invertebrates, and protons act as competitors to Mn toxicity in algae. The selected models are able to predict Mn toxicity to the test organisms to within a factor of 2 in most cases. Under low-pH conditions invertebrates are the most sensitive taxa, and under high-pH conditions algae are most sensitive. The point at which algae become more sensitive than invertebrates depends on the Ca concentration and occurs at higher pH when Ca concentrations are low, because of the sensitivity of invertebrates under these conditions. Dissolved organic carbon concentrations have very little effect on the toxicity of Mn to aquatic organisms. Copyright © 2011 SETAC.
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Rathnayake, I V N; Megharaj, Mallavarapu; Krishnamurti, G S R; Bolan, Nanthi S; Naidu, Ravi
2013-01-01
A new minimal medium was formulated considering the limitations of the existing media for testing heavy metal sensitivity to bacteria. Toxicity of cadmium and copper to three bacteria was investigated in the new medium and compared with three other media commonly used to study the effect of the toxic metals. Based on speciation data arrived at using ion-selective electrodes, the available free-metal concentration in solution was highest in the MES-buffered medium. This finding was strongly supported by the estimated EC(50) values for the metals tested based on the toxicity bioassays. The free-ionic cadmium and copper concentrations in the medium provide more accurate determination of metal concentrations that affects the bacteria, than with most of other existing media. This will avoid doubts on other media and misleading conclusions relevant to the toxicity of heavy metals to bacteria and provides a better option for the study of metal-bacteria interactions. Copyright © 2012 Elsevier Ltd. All rights reserved.
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Piñero, María Carmen; Pérez-Jiménez, Margarita; López-Marín, Josefa; Del Amor, Francisco M
2017-04-01
We investigated B tolerance in sweet pepper plants (Capsicum annuun L.) under an elevated CO 2 concentration, combined with the application of calcium as a nutrient management amelioration technique. The data show that high B affected the roots more than the aerial parts, since there was an increase in the shoot/root ratio, when plants were grown with high B levels; however, the impact was lessened when the plants were grown at elevated CO 2 , since the root FW reduction caused by excess B was less marked at the high CO 2 concentration (30.9% less). Additionally, the high B concentration affected the membrane permeability of roots, which increased from 39 to 54% at ambient CO 2 concentration, and from 38 to 51% at elevated CO 2 concentration, producing a cation imbalance in plants, which was differentially affected by the CO 2 supply. The Ca surplus in the nutrient solution reduced the nutritional imbalance in sweet pepper plants produced by the high B concentration, at both CO 2 concentrations. The medium B concentration treatment (toxic according to the literature) did not result in any toxic effect. Hence, there is a need to review the literature on critical and toxic B levels taking into account increases in atmospheric CO 2 .
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Toxicity of sediment-associated pesticides to Chironomus dilutus and Hyalella azteca.
Ding, Yuping; Weston, Donald P; You, Jing; Rothert, Amanda K; Lydy, Michael J
2011-07-01
Two hundred sediment samples were collected and their toxicity evaluated to aquatic species in a previous study in the agriculturally dominated Central Valley of California, United States. Pyrethroid insecticides were the main contributors to the observed toxicity. However, mortality in approximately one third of the toxic samples could not be explained solely by the presence of pyrethroids in the matrices. Hundreds of pesticides are currently used in the Central Valley of California, but only a few dozen are analyzed in standard environmental monitoring. A significant amount of unexplained sediment toxicity may be due to pesticides that are in widespread use that but have not been routinely monitored in the environment, and even if some of them were, the concentrations harmful to aquatic organisms are unknown. In this study, toxicity thresholds for nine sediment-associated pesticides including abamectin, diazinon, dicofol, fenpropathrin, indoxacarb, methyl parathion, oxyfluorfen, propargite, and pyraclostrobin were established for two aquatic species, the midge Chironomus dilutus and the amphipod Hyalella azteca. For midges, the median lethal concentration (LC₅₀) of the pesticides ranged from 0.18 to 964 μg/g organic carbon (OC), with abamectin being the most toxic and propargite being the least toxic pesticide. A sublethal growth endpoint using average individual ash-free dry mass was also measured for the midges. The no-observable effect concentration values for growth ranged from 0.10 to 633 μg/g OC for the nine pesticides. For the amphipods, fenpropathrin was the most toxic, with an LC₅₀ of 1-2 μg/g OC. Abamectin, diazinon, and methyl parathion were all moderately toxic (LC₅₀s 2.8-26 μg/g OC). Dicofol, indoxacarb, oxyfluorfen, propargite, and pyraclostrobin were all relatively nontoxic, with LC₅₀s greater than the highest concentrations tested. The toxicity information collected in the present study will be helpful in decreasing the frequency of unexplained sediment toxicity in agricultural waterways.
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Direct toxicity assessment - Methods, evaluation, interpretation.
Gruiz, Katalin; Fekete-Kertész, Ildikó; Kunglné-Nagy, Zsuzsanna; Hajdu, Csilla; Feigl, Viktória; Vaszita, Emese; Molnár, Mónika
2016-09-01
Direct toxicity assessment (DTA) results provide the scale of the actual adverse effect of contaminated environmental samples. DTA results are used in environmental risk management of contaminated water, soil and waste, without explicitly translating the results into chemical concentration. The end points are the same as in environmental toxicology in general, i.e. inhibition rate, decrease in the growth rate or in yield and the 'no effect' or the 'lowest effect' measurement points of the sample dilution-response curve. The measurement unit cannot be a concentration, since the contaminants and their content in the sample is unknown. Thus toxicity is expressed as the sample proportion causing a certain scale of inhibition or no inhibition. Another option for characterizing the scale of toxicity of an environmental sample is equivalencing. Toxicity equivalencing represents an interpretation tool which enables toxicity of unknown mixtures of chemicals be converted into the concentration of an equivalently toxic reference substance. Toxicity equivalencing, (i.e. expressing the toxicity of unknown contaminants as the concentration of the reference) makes DTA results better understandable for non-ecotoxicologists and other professionals educated and thinking based on the chemical model. This paper describes and discusses the role, the principles, the methodology and the interpretation of direct toxicity assessment (DTA) with the aim to contribute to the understanding of the necessity to integrate DTA results into environmental management of contaminated soil and water. The paper also introduces the benefits of the toxicity equivalency method. The use of DTA is illustrated through two case studies. The first case study focuses on DTA of treated wastewater with the aim to characterize the treatment efficacy of a biological wastewater treatment plant by frequent bioassaying. The second case study applied DTA to investigate the cover layers of two bauxite residue (red mud) reservoirs. Based on the DTA results the necessary toxicity attenuation rate of the cover layers was estimated. Copyright © 2016 Elsevier B.V. All rights reserved.
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Piola, Lucas; Fuchs, Julio; Oneto, María Luisa; Basack, Silvana; Kesten, Eva; Casabé, Norma
2013-04-01
Glyphosate-based products are the leading post-emergent agricultural herbicides in the world, particularly in association with glyphosate tolerant crops. However, studies on the effects of glyphosate-based formulations on terrestrial receptors are scarce. This study was conducted to evaluate the comparative toxicity of two glyphosate-based products: Roundup FG (monoammonium salt, 72% acid equivalent, glyphosate-A) and Mon 8750 (monoammonium salt, 85.4% acid equivalent, glyphosate-B), towards the earthworm Eisenia andrei. Median lethal concentration (LC50) showed that glyphosate-A was 4.5-fold more toxic than glyphosate-B. Sublethal concentrations caused a concentration-dependent weight loss, consistent with the reported effect of glyphosate as uncoupler of oxidative phosphorylation. Glyphosate-A showed deleterious effects on DNA and lysosomal damage at concentrations close to the applied environmental concentrations (14.4 μg ae cm(-2)). With glyphosate-B toxic effects were observed at higher doses, close to its LC50, suggesting that the higher toxicity of formulate A could be attributed to the effects of some of the so-called "inert ingredients", either due to a direct intrinsic toxicity, or to an enhancement in the bioavailability and/or bioaccumulation of the active ingredient. Our results highlight the importance of ecotoxicological assessment not only of the active ingredients, but also of the different formulations usually employed in agricultural practices. Copyright © 2012 Elsevier Ltd. All rights reserved.
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Hiusen, Timothy J; Kamble-Shripat, T
2013-08-01
By using a no-choice feeding bioassay, delayed toxicity and concentration-dependent mortality of two chitinolytic enzyme inhibitors, pentoxifylline and psammaplin A, were evaluated by determining LT50, LT90, and LT99 (lethal time) against the economically important eastern subterranean termite, Reticulitermes flavipes (Kollar). Pentoxifylline- and psammaplin A-incorporated diets (filter paper) were assayed at 0.01, 0.02, 0.04, 0.08, and 0.21% and 0.0375, 0.075, 0.15, and 0.3% active ingredient (wt:wt), respectively. Acetone-only treated filter paper served as diet for the control treatments. Termite workers were allowed to feed on diet until 100% test population mortality occurred (80-95 d). Both chitinase inhibitors were shown to be toxic to R. flavipes. Concentration-dependent toxicity occurred within the pentoxifylline treatments over the range of 0.01-0.08%, with 0.08% treatments producing an LT50 of 32.2 d. However, mortality in response to psammaplin A treatments lacked concentration-dependent toxicity. Treatment with 0.3% psammaplin A produced an LT50 of 21.3 d. Mortality in response to lower psammaplin A treatments displayed no concentration-dependent trends. This study provides the first report on delayed toxicity of chitinolytic enzyme inhibitors against eastern subterranean termites (order Isoptera) and toxicological data on pentoxifylline and psammaplin A over a range of concentrations.
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Liu, Kailin; Xu, Shiji; Zhang, Minghuan; Kou, Yahong; Zhou, Xiaomao; Luo, Kun; Hu, Lifeng; Liu, Xiangying; Liu, Min; Bai, Lianyang
2016-01-01
The toxicity of ionizable organic compounds to organisms depends on the pH, which therefore affects risk assessments of these compounds. However, there is not a direct chemical method to predict the toxicity of ionizable organic compounds. To determine whether hollow-fiber liquid-phase microextraction (HF-LPME) is applicable for this purpose, a three-phase HF-LPME was used to measure sulfadiazine and estimate its toxicity to Daphnia magna in solutions of different pH. The result indicated that the sulfadiazine concentrations measured by HF-LPME decreased with increasing pH, which is consistent with the decreased toxicity. The concentration immobilize 50% of the daphnids (EC50) in 48 h calculated from nominal concentrations increased from 11.93 to 273.5 mg L−1 as the pH increased from 6.0 to 8.5, and the coefficient of variation (CV) of the EC50 values reached 104.6%. When calculated from the concentrations measured by HF-LPME (pH 12 acceptor phase), the EC50 ranged from 223.4 to 394.6 mg L−1, and the CV decreased to 27.60%, suggesting that the concentrations measured by HF-LPME can be used to estimate the toxicity of sulfadiazine irrespective of the solution pH. PMID:28004779
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Acute toxicity of fire-control chemicals, nitrogenous chemicals, and surfactants to rainbow trout
Buhl, Kevin J.; Hamilton, Steven J.
2000-01-01
Laboratory studies were conducted to determine the acute toxicity of three ammonia-based fire retardants (Fire-Trol LCA-F, Fire-Trol LCM-R, and Phos-Chek 259F), five surfactant-based fire-suppressant foams (FireFoam 103B, FireFoam 104, Fire Quench, ForExpan S, and Pyrocap B-136), three nitrogenous chemicals (ammonia, nitrate, and nitrite), and two anionic surfactants (linear alkylbenzene sulfonate [LAS] and sodium dodecyl sulfate [SDS]) to juvenile rainbow trout Oncorhynchus mykiss in soft water. The descending rank order of toxicity (96-h concentration lethal to 50% of test organisms [96-h LC50]) for the fire retardants was as follows: Phos-Chek 259F (168 mg/L) > Fire-Trol LCA-F (942 mg/L) = Fire-Trol LCM-R (1,141 mg/L). The descending rank order of toxicity for the foams was as follows: FireFoam 103B (12.2 mg/L) = FireFoam 104 (13.0 mg/L) > ForExpan S (21.8 mg/L) > Fire Quench (39.0 mg/L) > Pyrocap B-136 [156 mg/L). Except for Pyrocap B-136, the foams were more toxic than the fire retardants. Un-ionized ammonia (NH3; 0.125 mg/L as N) was about six times more toxic than nitrite (0.79 mg/L NO2-N) and about 13,300 times more toxic than nitrate (1,658 mg/L NO3-N). Linear alkylbenzene sulfonate (5.0 mg/L) was about five times more toxic than SDS (24.9 mg/L). Estimated total ammonia and NH3 concentrations at the 96-h LC50s of the fire retardants indicated that ammonia was the primary toxic component in these formulations. Based on estimated anionic surfactant concentrations at the 96-h LC50s of the foams and reference surfactants, LAS was intermediate in toxicity and SDS was less toxic to rainbow trout when compared with the foams. Comparisons of recommended application concentrations to the test results indicate that accidental inputs of these chemicals into streams require substantial dilutions (100-1,750-fold to reach concentrations nonlethal to rainbow trout.
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The Effect of Sericin from Various Extraction Methods on Cell Viability and Collagen Production
Aramwit, Pornanong; Kanokpanont, Sorada; Nakpheng, Titpawan; Srichana, Teerapol
2010-01-01
Silk sericin (SS) can accelerate cell proliferation and attachment; however, SS can be extracted by various methods, which result in SS exhibiting different physical and biological properties. We found that SS produced from various extraction methods has different molecular weights, zeta potential, particle size and amino acid content. The MTT assay indicated that SS from all extraction methods had no toxicity to mouse fibroblast cells at concentrations up to 40 μg/mL after 24 h incubation, but SS obtained from some extraction methods can be toxic at higher concentrations. Heat-degraded SS was the least toxic to cells and activated the highest collagen production, while urea-extracted SS showed the lowest cell viability and collagen production. SS from urea extraction was severely harmful to cells at concentrations higher than 100 μg/mL. SS from all extraction methods could still promote collagen production in a concentration-dependent manner, even at high concentrations that are toxic to cells. PMID:20559510
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Loon, W.M.G.M. van; Hermens, J.L.M.
1994-12-31
A large part of all aquatic pollutants can be classified as narcosis-type (baseline toxicity) chemicals. Many chemicals contribute to a joint baseline aquatic toxicity even at trace concentrations. A novel surrogate parameter, which simulated bioconcentration of hydrophobic substances from water and estimates internal molar concentrations, has been explored by Verhaar et al.. These estimated biological concentrations can be used to predict narcosis-type toxic effects, using the Lethal Body Burden (LBB) concept. The authors applied this toxicological-analytical concept to river water, and some recent technological developments and field results are pointed out. The simulation of bioconcentration is performed by extracting watermore » samples with empore{trademark} disks. The authors developed two extraction procedures; i.e., laboratory extraction and field extraction. Molar concentrations measurements are performed using vapor pressure osmometry, GC-FID and GC-MS. Results on the molar concentrations of hydrophobic compounds which can be bioaccumulated from several Dutch river systems will be presented.« less
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Beylot, Antoine; Villeneuve, Jacques; Bellenfant, Gaël
2013-02-01
GOAL AND SCOPE: The life cycle inventory of landfill emissions is a key point in Life Cycle Assessment (LCA) of waste management options and is highly subject to discussion. Result sensitivity to data inventory is accounted for through the implementation of scenarios that help examine how waste landfilling should be modeled in LCA. Four landfill biogas management options are environmentally evaluated in a Life Cycle Assessment perspective: (1) no biogas management (open dump), conventional landfill with (2) flaring, (3) combined heat and power (CHP) production in an internal combustion engine and (4) biogas upgrading for use as a fuel in buses. Average, maximum and minimum literature values are considered both for combustion emission factors in flares and engines and for trace pollutant concentrations in biogas. Biogas upgrading for use as a fuel in buses appears as the most relevant option with respect to most non-toxic impact categories and ecotoxicity, when considering average values for trace gas concentrations and combustion emission factors. Biogas combustion in an engine for CHP production shows the best performances in terms of climate change, but generates significantly higher photochemical oxidant formation and marine eutrophication impact potentials than flaring or biogas upgrading for use as a fuel in buses. However the calculated environmental impact potentials of landfill biogas management options depend largely on the trace gas concentrations implemented in the model. The use of average or extreme values reported in the literature significantly modifies the impact potential of a given scenario (up to two orders of magnitude for open dumps with respect to human toxicity). This should be taken into account when comparing landfilling with other waste management options. Also, the actual performances of a landfill top cover (in terms of oxidation rates) and combustion technology (in terms of emission factors) appear as key parameters affecting the ranking of biogas management options. Copyright © 2012 Elsevier Ltd. All rights reserved.
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Hossain, Md Akil; Lee, Seung-Jin; Park, Ji-Yong; Reza, Md Ahsanur; Kim, Tae-Hwan; Lee, Ki-Ja; Suh, Joo-Won; Park, Seung-Chun
2015-11-04
Nymphaea tetragona is a widely distributed ornamental species with ethnomedicinal uses in the treatment of diarrhea, dysentery, eruptive fevers, and infections. The anti-infectious activities of this herb have already been assessed to clarify its traditional use as a medicine. In this study, we aimed to verify the inhibitory effects of N. tetragona 50% methanol extract (NTME) on quorum sensing (QS)-controlled virulence factors of bacteria since QS and its virulence factors are novel targets for antimicrobial therapy. The antibacterial activity of this extract was evaluated against Chromobacterium violaceum and Pseudomonas aeruginosa. The inhibition of the violacein pigment of C. violaceum by NTME was determined qualitative and quantitative using standard methods. The effects of NTME on swarming motility, biofilm viability, pyocyanin production, and LasA protease activity were evaluated using P. aeruginosa. Finally, the in vitro and in vivo cytotoxicity of NTME were verified by MTT assay and oral administration to rats, respectively. The extract had concentration-dependent antibacterial activity against gram-negative bacteria. NTME at 1/2× minimum inhibitory concentration (MIC), 1× MIC and 2× MIC significantly lowered the levels of violacein of C. violaceum compared to that of the control. The swarming motility of P. aeruginosa was inhibited by ≥70% by treatment with 1/2× MIC of NTME. There were remarkable reductions in pyocyanin production and LasA protease activity in the overnight culture supernatant of P. aeruginosa supplemented with NTME when compared with that of the untreated control. The confocal micrographs of 24h biofilms of P. aeruginosa exposed to NTME exhibited a lower number of live cells than the control. No toxic effect was observed in in vitro and in vivo cytotoxicity assays of NTME. NTME was demonstrated to have significant concentration-dependent inhibitory effects on quorum sensing-mediated virulence factors of bacteria with non-toxic properties, and could thus be a prospective quorum sensing inhibitor. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
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Novel nicotine analogues with potential anti-mycobacterial activity.
Gandhi, Paresh T; Athmaram, Thimmasandra Narayanappa; Arunkumar, Gundaiah Ramesh
2016-04-15
Tuberculosis (TB) is the second leading lethal infectious disease in the world after acquired immuno deficiency (AIDs). We have developed a series of twenty-five novel nicotine analogues with de-addiction property and tested them for their activity against Mycobacterium tuberculosis (MTB). In an effort to increase the specificity of action and directing nicotine analogues to target MTB, four promising compounds were further optimized via molecular docking studies against the Dihydrofolate reductase of MTB. After lead optimization, one nicotine analogue [3-(5-(3fluorophenyl)nicotinoyl)-1-methylpyrrolidin-2-one] exhibited minimum inhibitory concentration of 1 μg/mL (2.86 nM) against M. tuberculosis (H37Rv strain), a human pathogenic strain of clinically significant importance. Pharmacokinetic analysis of [3-(5-(3fluorophenyl)nicotinoyl)-1methylpyrrolidin-2-one] with lowest MIC value via oral route in Wistar rats revealed that at a dosage of 5 mg/kg body weight gave a maximum serum drug concentration (Cmax) of 2.86 μg/mL, Tmax of one hour and a half-life (T1/2) of more than 24 h and Volume of distribution (Vd) of 27.36 L. Whereas the parenteral (intra venous) route showed a Cmax of 3.37 μg/mL, Tmax of 0.05 h, T1/2 of 24 h and Vd equivalent to 23.18 L. The acute oral toxicity and repeated oral toxicity studies in female Wistar rats had an LD50>2000 mg/kg body weight. Our data suggests that nicotine derivatives developed in the present study has good metabolic stability with tunable pharmacokinetics (PK) with therapeutic potential to combat MTB. However, further in vivo studies for anti-tuberculosis activity and elucidation of mode of action could result in more promising novel drug for treating MTB. To the best of our knowledge this is the first report revealing the anti-mycobacterial potential of nicotine analogue at potential therapeutic concentrations. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Mehder, A O; Habibullah, Y B; Gondal, M A; Baig, Umair
2016-08-01
Laser Induced Breakdown Spectroscopy (LIBS) is demonstrated for the spectral analysis of nutritional and toxic elements present in several varieties of date fruit samples available in the Saudi Arabia market. The method analyzes the optical emission of a test sample when subjected to pulsed laser ablation. In this demonstration, our primary focus is on calcium (Ca) and magnesium (Mg), as nutritional elements, and on chromium (Cr), as a toxic element. The local thermodynamic equilibrium (LTE) condition was confirmed prior to the elemental characterization of date samples to ensure accuracy of the LIBS analysis. This was achieved by measuring parameters associated with the plasma, such as the electron temperature and the electron number density. These plasma parameters aid interpretation of processes such as ionization, dissociation, and excitation occurring in the plasma plume formed by ablating the date palm sample. The minimum detection limit was established from calibration curves that involved plotting the LIBS signal intensity as a function of standard date samples with known concentrations. The concentration of Ca and Mg detected in different varieties of date samples was between 187 and 515 and 35-196mgL(-1) respectively, while Cr concentration measured between 1.72 and 7.76mgL(-1). In order to optimize our LIBS system, we have studied how the LIBS signal intensity depends on the incident laser energy and the delay time. In order to validate our LIBS analysis results, standard techniques such as inductively coupled plasma mass spectrometry (ICP-MS) were also applied on an identical (duplicate) date samples as those used for the LIBS analysis. The LIBS results exhibit remarkable agreement with those obtained from the ICP-MS analysis. In addition, the finger print wavelengths of other elements present in date samples were also identified and are reported here, which has not been previously reported, to the best of our knowledge. Copyright © 2016 Elsevier B.V. All rights reserved.
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Buchwalter, D.B.; Cain, D.J.; Clements, W.H.; Luoma, S.N.
2007-01-01
Aquatic insects often dominate lotic ecosystems, yet these organisms are under-represented in trace metal toxicity databases. Furthermore, toxicity data for aquatic insects do not appear to reflect their actual sensitivities to metals in nature, because the concentrations required to elicit toxicity in the laboratory are considerably higher than those found to impact insect communities in the field. New approaches are therefore needed to better understand how and why insects are differentially susceptible to metal exposures. Biodynamic modeling is a powerful tool for understanding interspecific differences in trace metal bioaccumulation. Because bioaccumulation alone does not necessarily correlate with toxicity, we combined biokinetic parameters associated with dissolved cadmium exposures with studies of the subcellular compartmentalization of accumulated Cd. This combination of physiological traits allowed us to make predictions of susceptibility differences to dissolved Cd in three aquatic insect taxa: Ephemerella excrucians, Rhithrogena morrisoni, and Rhyacophila sp. We compared these predictions with long-term field monitoring data and toxicity tests with closely related taxa: Ephemerella infrequens, Rhithrogena hageni, and Rhyacophila brunea. Kinetic parameters allowed us to estimate steady-state concentrations, the time required to reach steady state, and the concentrations of Cd projected to be in potentially toxic compartments for different species. Species-specific physiological traits identified using biodynamic models provided a means for better understanding why toxicity assays with insects have failed to provide meaningful estimates for metal concentrations that would be expected to be protective in nature. ?? 2007 American Chemical Society.
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The toxicological properties of petroleum gases.
McKee, Richard H; Herron, Deborah; Saperstein, Mark; Podhasky, Paula; Hoffman, Gary M; Roberts, Linda
2014-01-01
To characterize the toxicological hazards of petroleum gases, 90-day inhalation toxicity (Organization for Economic Cooperation and Development [OECD] 413) and developmental toxicity (OECD 414) tests were conducted with liquefied propane gas (LPG) at concentrations of 1000, 5000, or 10,000 ppm. A micronucleus test (OECD 474) of LPG was also conducted. No systemic or developmental effects were observed; the overall no observed adverse effect concentration (NOAEC) was 10,000 ppm. Further, there was no effect of LPG exposure at levels up to 10,000 ppm on micronucleus induction and no evidence of bone marrow toxicity. Other alkane gases (ethane, propane, n-butane, and isobutane) were then evaluated in combined repeated exposure studies with reproduction/development toxicity screening tests (OECD 422). There were no toxicologically important changes in parameters relating to systemic toxicity or neurotoxicity for any of these gases at concentrations ranging from 9000 to 16,000 ppm. There was no evidence of effects on developmental or reproductive toxicity in the studies of ethane, propane, or n-butane at the highest concentrations tested. However, there was a reduction in mating in the high-exposure group (9000 ppm) of the isobutane study, which although not significantly different was outside the range previously observed in the testing laboratory. Assuming the reduction in mating to have been toxicologically significant, the NOAEC for the isobutane reproductive toxicity screening test was 3000 ppm (7125 mg/m(3)). A method is proposed by which the toxicity of any of the 106 complex petroleum gas streams can be estimated from its composition.
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A developmental toxicity bioassay was used in three experiments to evaluate drinking water concentrates for suitability in multigenerational studies. First, chlorinated water was concentrated 135 fold by reverse osmosis; select lost disinfection by-products were spiked back. Co...
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A developmental toxicity bioassay was used in three experiments to evaluate drinking water concentrates for suitability in multigenerational studies. First, chlorinated water was concentrated 135 fold by reverse osmosis; select lost disinfection by-products were spiked back. Conc...
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Performance of a pilot-scale constructed wetland system for treating simulated ash basin water.
Dorman, Lane; Castle, James W; Rodgers, John H
2009-05-01
A pilot-scale constructed wetland treatment system (CWTS) was designed and built to decrease the concentration and toxicity of constituents of concern in ash basin water from coal-burning power plants. The CWTS was designed to promote the following treatment processes for metals and metalloids: precipitation as non-bioavailable sulfides, co-precipitation with iron oxyhydroxides, and adsorption onto iron oxides. Concentrations of Zn, Cr, Hg, As, and Se in simulated ash basin water were reduced by the CWTS to less than USEPA-recommended water quality criteria. The removal efficiency (defined as the percent concentration decrease from influent to effluent) was dependent on the influent concentration of the constituent, while the extent of removal (defined as the concentration of a constituent of concern in the CWTS effluent) was independent of the influent concentration. Results from toxicity experiments illustrated that the CWTS eliminated influent toxicity with regard to survival and reduced influent toxicity with regard to reproduction. Reduction in potential for scale formation and biofouling was achieved through treatment of the simulated ash basin water by the pilot-scale CWTS.
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Patino, Reynaldo; Dawson, D.; VanLandeghem, Matthew M.
2014-01-01
Toxic blooms of golden alga (GA, Prymnesium parvum) in Texas typically occur in winter or early spring. In North America, they were first reported in Texas in the 1980s, and a marked range expansion occurred in 2001. Although there is concern about the influence of climate change on the future distribution of GA, factors responsible for past dispersals remain uncertain. To better understand the factors that influence toxic bloom dispersal in reservoirs, this study characterized reservoir water quality associated with toxic GA blooms since 2001, and examined trends in water quality during a 20-year period bracketing the 2001 expansion. Archived data were analyzed for six impacted and six nonimpacted reservoirs from two major Texas basins: Brazos River and Colorado River. Data were simplified for analysis by pooling spatially (across sampling stations) and temporally (winter, December-February) within reservoirs and generating depth-corrected (1 m) monthly values. Classification tree analysis [period of record (POR), 2001-2010] using salinity-associated variables (specific conductance, chloride, sulfate), dissolved oxygen (DO), pH, temperature, total hardness, potassium, nitrate+nitrite, and total phosphorus indicated that salinity best predicts the toxic bloom occurrence. Minimum estimated salinities for toxic bloom formation were 0.59 and 1.02 psu in Brazos and Colorado River reservoirs, respectively. Principal component analysis (POR, 2001-2010) indicated that GA habitat is best defined by higher salinity relative to nonimpacted reservoirs, with winter DO and pH also being slightly higher and winter temperature slightly lower in impacted reservoirs. Trend analysis, however, did not reveal monotonic changes in winter water quality of GA-impacted reservoirs during the 20-year period (1991-2010) bracketing the 2001 dispersal. Therefore, whereas minimum levels of salinity are required for GA establishment and toxic blooms in Texas reservoirs, the lack of trends in water quality suggests that conditions favorable for toxic blooms pre-date the 2001 expansion. These observations are consistent with a climate change-independent scenario of past GA dispersals in Texas reservoirs driven by novel introductions into pre-existing favorable habitat. Reports of latent GA populations in certain nonimpacted reservoirs, however, provide a plausible scenario of future dispersals characterized by prolonged periods between colonization and toxic bloom development and driven by changes in water quality, natural, or anthropogenic.
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Faulde, Michael K; Pages, Frederic; Uedelhoven, Waltraud
2016-04-01
Personal protective measures against hematophagous vectors constitute the first line of defense against arthropod-borne diseases. In this regard, a major advance has been the development of residual insecticides that can be impregnated into clothing. Currently, however, information on specific treatment procedures, initial insecticide concentrations, arthropod toxicity, residual activity, and laundering resistance is either fragmentary or non-existent, and no World Health Organization Pesticides Evaluation Scheme or other guidelines exist for the standardized testing and licensing of insecticide-treated clothing. The aim of this study was to analyze the insecticide content, contact toxicity, laundering resistance, and residual activity of five commercially available and commonly used permethrin-treated fabrics-Insect Shield, ExOfficio, Sol's Monarch T-shirts, battle dress uniforms (BDUs), and Labonal socks-against vector-competent Aedes aegypti, Anopheles stephensi, and Culex pipiens mosquitoes under laboratory conditions. Prior to laundering, permethrin concentrations ranged from 4300 to 870 mg/m(2) whereas, after 100 defined machine launderings, the remaining permethrin content fell to between 1800 and 20 mg/m(2), a percentage permethrin loss of 58.1 to 98.5 %. The highest 99 % knockdown (KD99) efficacy of permethrin was detected in Ae. aegypti, followed by An. stephensi and Cx. pipiens demonstrating that Ae. aegypti is the most sensitive species and Cx. pipiens the least sensitive. After 100 launderings, the remaining biocidal efficacy differed markedly among the five brands, with KD99 times varying from 38.8 ± 2.9 to >360 min for Ae. aegypti, from 44 ± 3.5 to >360 min for An. stephensi, and from 98 ± 10.6 to >360 min for Cx. pipiens. Overall, the ranking of the residual biocidal efficacies within the five brands tested was as follows: BDU ≈ Labonal > Sol's Monarch > ExOfficio > Insect Shield. When applying German Armed Forces licensing conditions, none of the four products available in the civilian market would completely meet all the necessary efficacy and safety requirements fulfilled by BDUs. Therefore, we strongly recommend standardized testing and licensing procedures for insecticide-treated clothing, with defined cutoff values for initial maximum and post-laundering minimum concentrations of permethrin as well as figures for permethrin migration rates, arthropod toxicity, homogeneity on fabrics, residual activity, and laundering resistance.
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USDA-ARS?s Scientific Manuscript database
Electronic systems consisting of renewable, biodegradable materials and minimum amounts of toxic materials are desirable. This study was carried out to investigate the electrosynthesis and evaluation of the electrochemical, morphological, and topographical characteristics of a novel conducting polyp...
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40 CFR 761.323 - Sample preparation.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 761.323 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL... Remediation Waste Samples § 761.323 Sample preparation. (a) The comparison study requires analysis of a minimum of 10 samples weighing at least 300 grams each. Samples of PCB remediation waste used in the...
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40 CFR 761.323 - Sample preparation.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 761.323 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL... Remediation Waste Samples § 761.323 Sample preparation. (a) The comparison study requires analysis of a minimum of 10 samples weighing at least 300 grams each. Samples of PCB remediation waste used in the...
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40 CFR 761.323 - Sample preparation.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 761.323 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL... Remediation Waste Samples § 761.323 Sample preparation. (a) The comparison study requires analysis of a minimum of 10 samples weighing at least 300 grams each. Samples of PCB remediation waste used in the...
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The cathepsin B inhibitor, z-FA-CMK is toxic and readily induced cell death in human T lymphocytes
DOE Office of Scientific and Technical Information (OSTI.GOV)
Liow, K.Y.; Chow, S.C., E-mail: chow.sek.chuen@monash.edu
The cathepsin B inhibitor, benzyloxycarbonyl-phenylalanine-alanine-chloromethylketone (z-FA-CMK) was found to be toxic and readily induced cell death in the human T cell line, Jurkat, whereas two other analogs benzyloxycarbonyl-phenylalanine-alanine-fluoromethylketone (z-FA-FMK) and benzyloxycarbonyl-phenylalanine-alanine-diazomethylketone (z-FA-DMK) were not toxic. The toxicity of z-FA-CMK requires not only the CMK group, but also the presence of alanine in the P1 position and the benzyloxycarbonyl group at the N-terminal. Dose–response studies showed that lower concentrations of z-FA-CMK induced apoptosis in Jurkat T cells whereas higher concentrations induced necrosis. In z-FA-CMK-induced apoptosis, both initiator caspases (-8 and -9) and effector caspases (-3, -6 and -7) were processed tomore » their respective subunits in Jurkat T cells. However, only the pro-form of the initiator caspases were reduced in z-FA-CMK-induced necrosis and no respective subunits were apparent. The caspase inihibitor benzyloxycarbonyl-valine-alanine-aspartic acid-(O-methyl)-fluoromehylketone (z-VAD-FMK) inhibits apoptosis and caspase processing in Jurkat T cells treated with low concentration of z-FA-CMK but has no effect on z-FA-CMK-induced necrosis and the loss of initiator caspases. This suggests that the loss of initiator caspases in Jurkat T cells during z-FA-CMK-induced necrosis is not a caspase-dependent process. Taken together, we have demonstrated that z-FA-CMK is toxic to Jurkat T cells and induces apoptosis at low concentrations, while at higher concentrations the cells die of necrosis. - Highlights: • z-FA-CMK is toxic and induce cell death in the human T cells. • z-FA-CMK toxicity requires the CMK group, alanine and the benzyloxycarbonyl group. • z-FA-CMK induced apoptosis at low concentration and necrosis at high concentration.« less
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Green, W. Reed; Galloway, Joel M.; Richards, Joseph M.; Wesolowski, Edwin A.
2003-01-01
Outflow from Table Rock Lake and other White River reservoirs support a cold-water trout fishery of substantial economic yield in south-central Missouri and north-central Arkansas. The Missouri Department of Conservation has requested an increase in existing minimum flows through the Table Rock Lake Dam from the U.S. Army Corps of Engineers to increase the quality of fishable waters downstream in Lake Taneycomo. Information is needed to assess the effect of increased minimum flows on temperature and dissolved- oxygen concentrations of reservoir water and the outflow. A two-dimensional, laterally averaged, hydrodynamic, temperature, and dissolved-oxygen model, CE-QUAL-W2, was developed and calibrated for Table Rock Lake, located in Missouri, north of the Arkansas-Missouri State line. The model simulates water-surface elevation, heat transport, and dissolved-oxygen dynamics. The model was developed to assess the effects of proposed increases in minimum flow from about 4.4 cubic meters per second (the existing minimum flow) to 11.3 cubic meters per second (the increased minimum flow). Simulations included assessing the effect of (1) increased minimum flows and (2) increased minimum flows with increased water-surface elevations in Table Rock Lake, on outflow temperatures and dissolved-oxygen concentrations. In both minimum flow scenarios, water temperature appeared to stay the same or increase slightly (less than 0.37 ?C) and dissolved oxygen appeared to decrease slightly (less than 0.78 mg/L) in the outflow during the thermal stratification season. However, differences between the minimum flow scenarios for water temperature and dissolved- oxygen concentration and the calibrated model were similar to the differences between measured and simulated water-column profile values.
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Microelectrode Array-evaluation of Neurotoxic Effects of Magnesium as an Implantable Biomaterial
Huang, Ting; Wang, Zhonghai; Wei, Lina; Kindy, Mark; Zheng, Yufeng; Xi, Tingfei; Gao, Bruce Z.
2016-01-01
Magnesium (Mg)-based biomaterials have shown great potential in clinical applications. However, the cytotoxic effects of excessive Mg2+ and the corrosion products from Mg-based biomaterials, particularly their effects on neurons, have been little studied. Although viability tests are most commonly used, a functional evaluation is critically needed. Here, both methyl thiazolyl tetrazolium (MTT) and lactate dehydrogenase (LDH) assays were used to test the effect of Mg2+ and Mg-extract solution on neuronal viability. Microelectrode arrays (MEAs), which provide long-term, real-time recording of extracellular electrophysiological signals of in vitro neuronal networks, were used to test for toxic effects. The minimum effective concentrations (ECmin) of Mg2+ from the MTT and LDH assays were 3 mmol/L and 100 mmol/L, respectively, while the ECmin obtained from the MEA assay was 0.1 mmol/L. MEA data revealed significant loss of neuronal network activity when the culture was exposed to 25% Mg-extract solution, a concentration that did not affect neuronal viability. For evaluating the biocompatibility of Mg-based biomaterials with neurons, MEA electrophysiological testing is a more precise method than basic cell-viability testing. PMID:27110081
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Microelectrode Array-evaluation of Neurotoxic Effects of Magnesium as an Implantable Biomaterial.
Huang, Ting; Wang, Zhonghai; Wei, Lina; Kindy, Mark; Zheng, Yufeng; Xi, Tingfei; Gao, Bruce Z
2016-01-01
Magnesium (Mg)-based biomaterials have shown great potential in clinical applications. However, the cytotoxic effects of excessive Mg 2+ and the corrosion products from Mg-based biomaterials, particularly their effects on neurons, have been little studied. Although viability tests are most commonly used, a functional evaluation is critically needed. Here, both methyl thiazolyl tetrazolium (MTT) and lactate dehydrogenase (LDH) assays were used to test the effect of Mg 2+ and Mg-extract solution on neuronal viability. Microelectrode arrays (MEAs), which provide long-term, real-time recording of extracellular electrophysiological signals of in vitro neuronal networks, were used to test for toxic effects. The minimum effective concentrations (EC min ) of Mg 2+ from the MTT and LDH assays were 3 mmol/L and 100 mmol/L, respectively, while the EC min obtained from the MEA assay was 0.1 mmol/L. MEA data revealed significant loss of neuronal network activity when the culture was exposed to 25% Mg-extract solution, a concentration that did not affect neuronal viability. For evaluating the biocompatibility of Mg-based biomaterials with neurons, MEA electrophysiological testing is a more precise method than basic cell-viability testing.
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Role of microextraction sampling procedures in forensic toxicology.
Barroso, Mário; Moreno, Ivo; da Fonseca, Beatriz; Queiroz, João António; Gallardo, Eugenia
2012-07-01
The last two decades have provided analysts with more sensitive technology, enabling scientists from all analytical fields to see what they were not able to see just a few years ago. This increased sensitivity has allowed drug detection at very low concentrations and testing in unconventional samples (e.g., hair, oral fluid and sweat), where despite having low analyte concentrations has also led to a reduction in sample size. Along with this reduction, and as a result of the use of excessive amounts of potentially toxic organic solvents (with the subsequent environmental pollution and costs associated with their proper disposal), there has been a growing tendency to use miniaturized sampling techniques. Those sampling procedures allow reducing organic solvent consumption to a minimum and at the same time provide a rapid, simple and cost-effective approach. In addition, it is possible to get at least some degree of automation when using these techniques, which will enhance sample throughput. Those miniaturized sample preparation techniques may be roughly categorized in solid-phase and liquid-phase microextraction, depending on the nature of the analyte. This paper reviews recently published literature on the use of microextraction sampling procedures, with a special focus on the field of forensic toxicology.
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How low can you go? Assessing minimum concentrations of NSC in carbon limited tree saplings
NASA Astrophysics Data System (ADS)
Hoch, Guenter; Hartmann, Henrik; Schwendener, Andrea
2016-04-01
Tissue concentrations of non-structural carbohydrates (NSC) are frequently used to determine the carbon balance of plants. Over the last years, an increasing number of studies have inferred carbon starvation in trees under environmental stress like drought from low tissue NSC concentrations. However, such inferences are limited by the fact that minimum concentrations of NSC required for survival are not known. So far, it was hypothesized that even under lethal carbon starvation, starch and low molecular sugar concentrations cannot be completely depleted and that minimum NSC concentrations at death vary across tissues and species. Here we present results of an experiment that aimed to determine minimum NSC concentrations in different tissues of saplings of two broad-leaved tree species (Acer pseudoplatanus and Quercus petratea) exposed to lethal carbon starvation via continuous darkening. In addition, we investigated recovery rates of NSC concentrations in saplings that had been darkened for different periods of time and were then re-exposed to light. Both species survived continuous darkening for about 12 weeks (confirmed by testing the ability to re-sprout after darkness). In all investigated tissues, starch concentrations declined close to zero within three to six weeks of darkness. Low molecular sugars also decreased strongly within the first weeks of darkness, but seemed to stabilize at low concentrations of 0.5 to 2 % dry matter (depending on tissue and species) almost until death. NSC concentrations recovered surprisingly fast in saplings that were re-exposed to light. After 3 weeks of continuous darkness, tissue NSC concentrations recovered within 6 weeks to levels of unshaded control saplings in all tissues and in both species. To our knowledge, this study represents the first experimental attempt to quantify minimum tissue NSC concentrations at lethal carbon starvation. Most importantly, our results suggest that carbon-starved tree saplings are able to survive several weeks without starch reserves and with extremely low sugar concentrations in all organs. Although it remains to be tested whether our findings are also valid for mature trees, these results show that NSC pools in trees are very sensitive to carbon limitation and that lethal carbon starvation is preceded by a significant (almost complete) depletion of starch and sugars in all tree organs.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Huebert, D.B.
1992-01-01
The duckweed Lemna trisulca L. was grown in axenic cultures in a filter-sterilized medium. A portion of the medium was replaced regularly during experiments. The amount replaced doubled every two days. metal concentrations in the medium wee measured on the last day of experiments. The only organic compound added was FeEDTA at a concentration of 9 [mu]M. The chelating capacity of the medium was therefore minimal, defined and controlled. The nutrient medium and environmental conditions supported a doubling time of 1.6 to 2.4 days over a 14 day culture period. Under the above conditions, the EC50 (concentration at which amore » 50% effect is observed) for Cd and 0.99 [mu]M based on multiplication rate and 0.56 [mu]M based on final yield. The NOEC (no observable effect concentration) for Cd was between 120 and 150 [mu]g Cd/g dry wt. based on internal Cd, and 0.08 [mu]M based on external Cd. Internal Cd may be a superior estimate of toxicity because it avoids the problems associated with metal speciation in the external medium and allows for a comparison with field data. Lemna trisulca responded within 2 days to the addition of 0.64 [mu]M Cd. No tolerance to Cd was induced even after 6 weeks of exposure. The calculated response of L. trisulca to Cd may have been influenced by the multiplication rate of control cultures, which varied from 1.6 to 2.4 days. Calcium had no effect on Cd uptake or toxicity. Zinc antagonized Cd toxicity but had a variable effect on Cd uptake depending on its concentration. Zinc was about fifteen times less toxic than Cd. The uptake and toxicity of Cd and Zn were almost completely prevented when the level of available EDTA was in excess of the CD or Zn concentration. These data indicate that biological and chemical factors can profoundly influence the effect of toxicants on living organisms. These factors must be considered to ensure that toxicity studies are not confounded by effects extraneous to the actual effect of the toxicant.« less
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Temperature preference as an indicator of the chronic toxicity of cupric ions to Mozambique Tilapia
DOE Office of Scientific and Technical Information (OSTI.GOV)
Welch, T.J.; Stauffer, J.R. Jr.; Morgan, R.P. II
1989-11-01
Evaluation of the effects of environmental contaminants on aquatic communities has focused primarily on acute bioassays. These bioassays provide rapid and reproducible concentration response curves based on death as an endpoint. In recent years, however, emphasis has shifted towards monitoring sublethal effects of toxicants. Temperature is an easily quantifiable parameter influencing both the behavior and survival of fishes. As poikilotherms, fish use behavioral responses to help regulate body temperature. Fish thermoregulatory behavior may be altered by various toxic substances. Some researchers found that a 24 hr exposure of sublethal concentrations of copper caused a significant decrease in preferred temperature ofmore » fathead minnows (Pimephales promelas), although the results were confounded due to variations in copper concentrations. In this study, the authors examined the feasibility of using acute temperature preference tests to assess the chronic toxicity of low concentrations of free cupric ions to Mozambique tilapia, Oreochromis mossambicus (Peters).« less
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Liu, Kailin; Wang, Shaoyun; Luo, Kun; Liu, Xiangying; Yu, Yunlong
2013-12-01
Ameliorating acidic soils is a common practice and may affect the bioavailability of an ionizable organic pollutant to organisms. The toxicity of the weak base carbendazim to the earthworm (Eisenia fetida) was studied in an acidic soil (pH-H₂O, 4.6) and in the ameliorated soil (pH-H₂O, 7.5). The results indicated that the median lethal concentration of carbendazim for E. fetida decreased from 21.8 mg/kg in acidic soil to 7.35 mg/kg in the ameliorated soil. To understand why the amelioration increased carbendazim toxicity to the earthworm, the authors measured the carbendazim concentrations in the soil porewater. The authors found increased carbendazim concentrations in porewater, resulting in increased toxicity of carbendazim to earthworms. The increased pore concentrations result from decreased adsorption because of the effects of pH and calcium ions. © 2013 SETAC.
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MacDonald, Donald D.; Dipinto, Lisa M.; Field, Jay; Ingersoll, Christopher G.; Long, Edward R.; Swartz, Richard C.
2000-01-01
Sediment-quality guidelines (SQGs) have been published for polychlorinated biphenyls (PCBs) using both empirical and theoretical approaches. Empirically based guidelines have been developed using the screening-level concentration, effects range, effects level, and apparent effects threshold approaches. Theoretically based guidelines have been developed using the equilibrium-partitioning approach. Empirically-based guidelines were classified into three general categories, in accordance with their original narrative intents, and used to develop three consensus-based sediment effect concentrations (SECs) for total PCBs (tPCBs), including a threshold effect concentration, a midrange effect concentration, and an extreme effect concentration. Consensus-based SECs were derived because they estimate the central tendency of the published SQGs and, thus, reconcile the guidance values that have been derived using various approaches. Initially, consensus-based SECs for tPCBs were developed separately for freshwater sediments and for marine and estuarine sediments. Because the respective SECs were statistically similar, the underlying SQGs were subsequently merged and used to formulate more generally applicable SECs. The three consensus-based SECs were then evaluated for reliability using matching sediment chemistry and toxicity data from field studies, dose-response data from spiked-sediment toxicity tests, and SQGs derived from the equilibrium-partitioning approach. The results of this evaluation demonstrated that the consensus-based SECs can accurately predict both the presence and absence of toxicity in field-collected sediments. Importantly, the incidence of toxicity increases incrementally with increasing concentrations of tPCBs. Moreover, the consensus-based SECs are comparable to the chronic toxicity thresholds that have been estimated from dose-response data and equilibrium-partitioning models. Therefore, consensus-based SECs provide a unifying synthesis of existing SQGs, reflect causal rather than correlative effects, and accurately predict sediment toxicity in PCB-contaminated sediments.
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Boron toxicity is alleviated by hydrogen sulfide in cucumber (Cucumis sativus L.) seedlings.
Wang, Bao-Lan; Shi, Lei; Li, Yin-Xing; Zhang, Wen-Hao
2010-05-01
Boron (B) is an essential micronutrient for plants, which when occurs in excess in the growth medium, becomes toxic to plants. Rapid inhibition of root elongation is one of the most distinct symptoms of B toxicity. Hydrogen sulfide (H(2)S) is emerging as a potential messenger molecule involved in modulation of physiological processes in plants. In the present study, we investigated the role of H(2)S in B toxicity in cucumber (Cucumis sativus) seedlings. Root elongation was significantly inhibited by exposure of cucumber seedlings to solutions containing 5 mM B. The inhibitory effect of B on root elongation was substantially alleviated by treatment with H(2)S donor sodium hydrosulfide (NaHS). There was an increase in the activity of pectin methylesterase (PME) and up-regulated expression of genes encoding PME (CsPME) and expansin (CsExp) on exposure to high B concentration. The increase in PME activity and up-regulation of expression of CsPME and CsExp induced by high B concentration were markedly reduced in the presence of H(2)S donor. There was a rapid increase in soluble B concentrations in roots on exposure to high concentration B solutions. Treatment with H(2)S donor led to a transient reduction in soluble B concentration in roots such that no differences in soluble B concentrations in roots in the absence and presence of NaHS were found after 8 h exposure to the high concentration B solutions. These findings suggest that increases in activities of PME and expansin may underlie the inhibition of root elongation by toxic B, and that H(2)S plays an ameliorative role in protection of plants from B toxicity by counteracting B-induced up-regulation of cell wall-associated proteins of PME and expansins.
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Gao, Yue; Baisch, Paulo; Mirlean, Nicolai; Rodrigues da Silva Júnior, Flavio Manoel; Van Larebeke, Nik; Baeyens, Willy; Leermakers, Martine
2018-01-01
In North Sea and Port Açu (Brazil) coastal areas, high arsenic (As) concentrations were observed in water, soil and sediments. Therefore, the impact of this contamination on fish and shellfish species bought from local fishermen was studied. Total As was assessed with ICP-OES (Brazil) and ICP-MS (North Sea) after microwave digestion. Toxic As was assessed with liquid chromatography-ICP-MS (Brazil) and hydride generation-atomic fluorescence spectrometry (North Sea). All analytical methods comply with Quality Assurance/Quality Control procedures. Several fish species have average Total As concentrations above 1 μg g-1 wet weight (ww), but the highest concentrations are found in less spotted dogfish, lemon sole and whelks from the North Sea, with respectively 50, 49 and 50 μg g-1 ww. High Total As concentrations correspond to high Toxic As concentrations, except for scallops having increased Toxic As concentrations. Toxic As fractions are highest in scallops (almost 10%) but rarely exceeds 2% in all other species. Liver samples were only analyzed in ray, dogfish and catfish and their Toxic As fractions are between 2 and 4 times higher than in muscle. For a consumption of 150 g of seafood, only 3 samples exceed the provisional total daily intake of 2 μg kg-1 bw, however, cancer risks are non-negligible. Using mean Toxic As concentrations for each of the different fish and shellfish species studied, Lifetime Cancer Risk values at the actual global seafood consumption rate of 54 g day-1 are above 10-4 for whelks, scallops, dogfish, ray and lemon sole. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Stevens, An-Sofie; Pirotte, Nicky; Plusquin, Michelle; Willems, Maxime; Neyens, Thomas; Artois, Tom; Smeets, Karen
2015-03-01
To investigate hydrophobic test compounds in toxicological studies, solvents like dimethylsulfoxide (DMSO) are inevitable. However, using these solvents, the interpretation of test compound-induced responses can be biased. DMSO concentration guidelines are available, but are mostly based on acute exposures involving one specific toxicity endpoint. Hence, to avoid solvent-toxicant interference, we use multiple chronic test endpoints for additional interpretation of DMSO concentrations and propose a statistical model to assess possible synergistic, antagonistic or additive effects of test compounds and their solvents. In this study, the effects of both short- (1 day) and long-term (2 weeks) exposures to low DMSO concentrations (up to 1000 µl l(-1) ) were studied in the planarian Schmidtea mediterranea. We measured different biological levels in both fully developed and developing animals. In a long-term exposure set-up, a concentration of 500 µl l(-1) DMSO interfered with processes on different biological levels, e.g. behaviour, stem cell proliferation and gene expression profiles. After short exposure times, 500 µl l(-1) DMSO only affected motility, whereas the most significant changes on different parameters were observed at a concentration of 1000 µl l(-1) DMSO. As small sensitivity differences exist between biological levels and developmental stages, we advise the use of this solvent in concentrations below 500 µl l(-1) in this organism. In the second part of our study, we propose a statistical approach to account for solvent-toxicant interactions and discuss full-scale solvent toxicity studies. In conclusion, we reassessed DMSO concentration limits for different experimental endpoints in the planarian S. mediterranea. Copyright © 2014 John Wiley & Sons, Ltd.
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Toxicity of acid mine pit lake water remediated with limestone and phosphorus.
Neil, Luke L; McCullough, Clint D; Lund, Mark A; Evans, Louis H; Tsvetnenko, Yuri
2009-11-01
Pit lakes are increasingly common worldwide and have potential to provide many benefits. However, lake water toxicity may require remediation before beneficial end uses can be realised. Three treatments to remediate AMD (pH approximately 4.8) pit lake water containing elevated concentrations of Al and Zn from Collie, Western Australia were tested in mesocosms. Treatments were: (a) limestone neutralisation (L), (b) phosphorus amendment (P), and (c) combined limestone neutralisation and phosphorus amendment (L+P). Laboratory bioassays with Ceriodaphnia cf. dubia, Chlorella protothecoides and Tetrahymena thermophila assessed remediation. Limestone neutralisation increased pH and reduced heavy metal concentrations by 98% (Al) to 14% (Mg), removing toxicity to the three test species within 2 months. Phosphorus amendment removed toxicity after 6 months of treatment. However, phosphorus amendment to prior limestone neutralisation failed to reduce toxicity more than limestone neutralisation alone. Low concentrations of both phosphorus and nitrogen appear to limit phytoplankton population growth in all treatments.
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Chronic toxicity of a laundry detergent to the freshwater flagellate Euglena gracilis.
Azizullah, Azizullah; Richter, Peter; Jamil, Muhammad; Häder, Donat-Peter
2012-10-01
Chronic toxicity of the common laundry detergent Ariel on the freshwater alga Euglena gracilis was investigated by growing the alga in a medium containing the detergent for 7 days. Cell density, motility, swimming velocity, gravitactic orientation, cell shape, photosynthesis and concentration of light-harvesting pigments were used as end point parameters for the assessment of toxicity. Cell density was significantly reduced at a concentration of 1 mg l(-1) or above. Among the other tested parameters, with the exception of cell shape, gravitaxis and chlorophyll b, all were adversely affected by the detergent at concentrations exceeding 1 mg l(-1). It is concluded that long-term (7-days) exposure to the detergent caused significant toxicity to E. gracilis. Furthermore, long-term tests with E. gracilis can be used as sensitive indicator for the toxicity assessment of laundry detergents in aquatic environments.
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Książyk, Małgorzata; Asztemborska, Monika; Stęborowski, Romuald; Bystrzejewska-Piotrowska, Grażyna
2015-05-01
The growing use of nanoparticles in a wide range of products has resulted in their release into the aquatic environment; therefore, an understanding of the toxic effects of nanoparticles on aquatic organisms is of permanent importance. The aim of this study was to evaluate the toxicity of silver and platinum nanoparticles toward the freshwater microalga, Pseudokirchneriella subcapitata. Algal growth and photosynthetic pigments were determined to quantitate the effects of varying concentrations of Ag and Pt nanoparticles. The silver nanoparticles were much more toxic than the platinum ones. The concentrations causing total inhibition of algal growth were 5.0 and 22.2 mg L(-1), respectively. Similar results were obtained by analyzing the concentration of photosynthetic pigments in P. subcapitata exposed to nanoparticles. Thus, simple spectrophotometric determination of chlorophyll is a convenient tool for the analysis of nanoparticle toxicity to algae.
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Bosse, Casey; Rosen, Gunther; Colvin, Marienne; Earley, Patrick; Santore, Robert; Rivera-Duarte, Ignacio
2014-08-15
The bioavailability and toxicity of copper (Cu) in Shelter Island Yacht Basin (SIYB), San Diego, CA, USA, was assessed with simultaneous toxicological, chemical, and modeling approaches. Toxicological measurements included laboratory toxicity testing with Mytilus galloprovincialis (Mediterranean mussel) embryos added to both site water (ambient) and site water spiked with multiple Cu concentrations. Chemical assessment of ambient samples included total and dissolved Cu concentrations, and Cu complexation capacity measurements. Modeling was based on chemical speciation and predictions of bioavailability and toxicity using a marine Biotic Ligand Model (BLM). Cumulatively, these methods assessed the natural buffering capacity of Cu in SIYB during singular wet and dry season sampling events. Overall, the three approaches suggested negligible bioavailability, and isolated observed or predicted toxicity, despite an observed gradient of increasing Cu concentration, both horizontally and vertically within the water body, exceeding current water quality criteria for saltwater. Published by Elsevier Ltd.
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Acute and early life stage toxicity of industrial effluent on Japanese medaka (Oryzias latipes).
Zha, Jinmiao; Wang, Zijian
2006-03-15
To develop the whole effluent toxicity testing methods (WET), embryo larval stage toxicity test using Japanese medaka (Oryzias latipes) was conducted to evaluate an effluent from a banknote printing plant (BPP). The method is based on acute toxicity using endpoint of 96-h larval morality and on chronic toxicity using endpoints such as the time to hatch, hatching success, deformity, growth rate, swim-up failure, accumulative mortality and sexual ratio. In test for 96-h larval mortality, LC50 (the concentration was lethal to 50% of newly hatching medaka larvae) was 72.9%. In chronic toxicity test, newly fertilized embryos (<5-h old) were exposed to 1%, 6.25%, 12.5%, 25%, 50% effluent concentrations and to 200 mug/l BPA in a 24-h static renewal system at 25+/-1 degrees C until 15 day post-hatch. The results showed that all chronic endpoints were significantly different from the control at 50% dilution (p < 0.01). Embryos began to show lesions on 4th day at higher concentrations (12.5%, 25%, 50% BPP effluent concentrations). Treatment group of 25% dilution showed delayed time to hatch. A reduction in body weight was observed at 25% dilutions for males and females, respectively. Deformities were observed in newly hatched larvae at 25% and 50% BPP effluent concentrations. At 25% dilution, sex ratio of larvae was alternated and there was feminization phenomenon. We conclude that embryo larval stage test using medaka is feasible to evaluate both acute and chronic toxicities and potential endocrine disrupting activity of industrial effluents.
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Koppel, Darren J; Gissi, Francesca; Adams, Merrin S; King, Catherine K; Jolley, Dianne F
2017-09-01
The paucity of ecotoxicological data for Antarctic organisms is impeding the development of region-specific water quality guidelines. To address this limitation, toxicity testing protocols need to be developed to account for the unique physiology of polar organisms, in particular their slow growth rates. In this study, a toxicity test protocol was developed to investigate the toxicities of five metals to the polar marine microalga Cryothecomonas armigera. The concentrations which reduced population growth rate by 10% (EC10) after 24-d for Cu, Pb, Zn, Cd and Ni were 21.6, 152, 366, 454, and 1220 μg.L -1 , respectively. At the concentrations used in tests, only Cu and Ni were sufficiently toxic to enable the derivation of EC50 values of 63.1 and 1570 μg.L -1 respectively. All metals affected C. armigera's cellular physiology including cellular chlorophyll a fluorescence, cell complexity and size, and lipid concentrations. However, no changes to cellular membrane permeability were observed. The reduction in cellular lipid concentrations was a more sensitive indicator of toxicity for Cd, Ni, and Pb than growth rate inhibition, with EC10 values of 89, 894, and 11 μg.L -1 , respectively, highlighting its potential as a sensitive measure of metal toxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Severson, R.C.; Gough, L.P.
1992-01-01
Relationships between total Se and S or soluble SeO4 and SO4 in soils and tissue concentrations in alfalfa (Medicago sativa L.), under field conditions in the San Joaquin Valley of California, suggest that the rate of accumulation of Se in alfalfa may be reduced in areas where high Se and S concentrations in soils were measured. These data suggest that the balance between carbonate and sulfate minerals in soil may have a greater influence on uptake of Se by alfalfa than does the balance of SeO4 and SO4 in soil solution. Soil and alfalfa were sampled from areas representing a wide range in soil Se and S concentrations. Specific sampling locations were selected based on a previous study of Se, S, and other elements where 721 soil samples were collected to map landscape variability and distribution of elements. Six multiple-linear regression equations were developed between total and/or soluble soil chemical constituents and tissue concentrations of Se in alfalfa. We chose a regression model that accounted for 72% of the variability in alfalfa Se concentrations based on an association of elements in soil (total C, S, Se, and Sr) determined by factor analysis. To prepare a map showing the spatial distribution of estimated alfalfa Se concentrations, the model was applied to the data from the previously collected 721 soil samples. Estimated alfalfa Se concentrations in most of the study area were within a range that is predicted to produce alfalfa with neither Se deficiency nor toxicity when consumed by livestock. A few small areas are predicted to produce alfalfa that potentially would not meet minimum dietary needs of livestock.
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Maina, Angeline W.; Wagacha, John M.
2017-01-01
The objective of this study was to evaluate the antifungal activity of essential oil (EO) of Eucalyptus camaldulensis Dehnh. against five Fusarium spp. commonly associated with maize. The essential oil had been extracted by steam distillation in a modified Clevenger-type apparatus from leaves of E. camaldulensis and their chemical composition characterized by gas chromatography mass spectrometry. Poisoned food technique was used to determine the percentage inhibition of mycelial growth, minimum inhibitory concentration, and minimum fungicidal concentration of the EO on the test pathogens. Antifungal activity of different concentrations of the EO was evaluated using disc diffusion method. The most abundant compounds identified in the EO were 1,8-cineole (16.2%), α-pinene (15.6%), α-phellandrene (10.0%), and p-cymene (8.1%). The EO produced complete mycelial growth inhibition in all the test pathogens at a concentration of 7-8 μL/mL after five days of incubation. The minimum inhibitory concentration and minimum fungicidal concentration of the EO on the test fungi were in the range of 7-8 μL/mL and 8–10 μL/mL, respectively. These findings confirm the fungicidal properties of E. camaldulensis essential oils and their potential use in the management of economically important Fusarium spp. and as possible alternatives to synthetic fungicides. PMID:28127308
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USDA-ARS?s Scientific Manuscript database
The effect of daily minimum dissolved oxygen concentration on growth and yield (kg/ha) of the channel catfish (Ictalurus punctatus) and the channel x blue hybrid catfish (I. punctatus female x I. furcatus male), which shared the Jubilee strain of channel catfish as the maternal parent, was evaluated...
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Lasier, Peter J.; Hardin, Ian R.
2010-01-01
Chronic toxicities of Cl-, SO42-, and HCO3- to Ceriodaphnia dubia were evaluated in low- and moderate-hardness waters using a three-brood reproduction test method. Toxicity tests of anion mixtures were used to determine interaction effects and to produce models predicting C. dubia reproduction. Effluents diluted with low- and moderate-hardness waters were tested with animals acclimated to low- and moderate-hardness conditions to evaluate the models and to assess the effects of hardness and acclimation. Sulfate was significantly less toxic than Cl- and HCO3- in both types of water. Chloride and HCO3- toxicities were similar in low-hardness water, but HCO3- was the most toxic in moderate-hardness water. Low acute-to-chronic ratios indicate that toxicities of these anions will decrease quickly with dilution. Hardness significantly reduced Cl- and SO42- toxicity but had little effect on HCO3-. Chloride toxicity decreased with an increase in Na+ concentration, and CO3- toxicity may have been reduced by the dissolved organic carbon in effluent. Multivariate models using measured anion concentrations in effluents with low to moderate hardness levels provided fairly accurate predictions of reproduction. Determinations of toxicity for several effluents differed significantly depending on the hardness of the dilution water and the hardness of the water used to culture test animals. These results can be used to predict the contribution of elevated anion concentrations to the chronic toxicity of effluents; to identify effluents that are toxic due to contaminants other than Cl-, SO42-, and HCO3-; and to provide a basis for chemical substitutions in manufacturing processes.
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Corsi, Steven R; Geis, Steven W; Loyo-Rosales, Jorge E; Rice, Clifford P
2006-12-01
Characterization of the effects of aircraft deicer and anti-icer fluid (ADAF) runoff on aquatic organisms in receiving streams is a complex issue because the identities of numerous toxic additives are proprietary and not publicly available. Most potentially toxic and endocrine disrupting effects caused by ADAF are due to the numerous additive package ingredients which vary among manufacturers and types of ADAF formulation. Toxicity investigations of nine ADAF formulations indicate that endpoint concentrations for formulations of different manufacturers are widely variable. Type IV ADAF (anti-icers) are more toxic than Type I (deicers) for the four organisms tested (Vibrio fischeri, Pimephales promelas, Ceriodaphnia dubia, and Selenastrum capricornutum). Acute toxicity endpoint concentrations ranged from 347 to 7700 mg/L as ADAF for Type IV and from 1550 to 45,100 mg/L for Type I formulations. Chronic endpoint concentrations ranged from 70 to 1300 mg/L for Type IV and from 37 to 18,400 mg/L for Type I formulations. Alkylphenol ethoxylates and tolyltriazoles are two known classes of additives. Nonylphenol, nonylphenol ethoxylates, octylphenol, octylphenol ethoxylates, and 4,5-methyl-1H-benzotriazoles were quantified in the nine ADAF formulations, and toxicity tests were conducted with nonylphenol ethoxylates and 4,5-methyl-1H-benzotriazoles. Toxicity units computed for glycol and these additives, with respect to toxicity of the ADAF formulations, indicate that a portion of ADAF toxicity can be explained by the known additives and glycols, but much of the toxicity is due to unidentified additives.
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Thomas, Philippe J; Mineau, Pierre; Shore, Richard F; Champoux, Louise; Martin, Pamela A; Wilson, Laurie K; Fitzgerald, Guy; Elliott, John E
2011-07-01
Second-generation anticoagulant rodenticides (SGARs) are widely used to control rodent pests but exposure and poisonings occur in non-target species, such as birds of prey. Liver residues are often analysed to detect exposure in birds found dead but their use to assess toxicity of SGARs is problematic. We analysed published data on hepatic rodenticide residues and associated symptoms of anticoagulant poisoning from 270 birds of prey using logistic regression to estimate the probability of toxicosis associated with different liver SGAR residues. We also evaluated exposure to SGARs on a national level in Canada by analysing 196 livers from great horned owls (Bubo virginianus) and red-tailed hawks (Buteo jamaicensis) found dead at locations across the country. Analysis of a broader sample of raptor species from Quebec also helped define the taxonomic breadth of contamination. Calculated probability curves suggest significant species differences in sensitivity to SGARs and significant likelihood of toxicosis below previously suggested concentrations of concern (<0.1mg/kg). Analysis of birds from Quebec showed that a broad range of raptor species are exposed to SGARs, indicating that generalised terrestrial food chains could be contaminated in the vicinity of the sampled areas. Of the two species for which we had samples from across Canada, great horned owls are exposed to SGARs to a greater extent than red-tailed hawks and the liver residue levels were also higher. Using our probability estimates of effect, we estimate that a minimum of 11% of the sampled great horned owl population is at risk of being directly killed by SGARs. This is the first time the potential mortality impact of SGARs on a raptor population has been estimated. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.
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Shahid, Naeem; Becker, Jeremias Martin; Krauss, Martin; Brack, Werner; Liess, Matthias
2018-06-22
Risk assessments of toxicants in aquatic environments are typically based on the evaluation of concentrations in water or sediment. However, concentrations in water are highly variable, while the body burden may provide a better time-integrated measure of pesticide exposure and potential effects in aquatic organisms. Here, we quantified pesticide body burdens in a dominant invertebrate species from agricultural streams, Gammarus pulex, compared them pesticide concentrations in water samples, and linked the pesticide contamination with observed ecological effects on macroinvertebrate communities. In total, 19 of 61 targeted analytes were found in the organisms, ranging from 0.037 to 93.94 ng g-1 (wet weight). Neonicotinoids caused the highest toxic pressure among the pesticides detected in G. pulex. Using linear solvation energy relationships (LSERs), we derived equivalent pesticide concentrations in stream water based on the body burden. These equivalent concentrations correlated with the concentrations in water samples collected after run-off (65% of variance explained). Pesticide pressure significantly affected the aquatic macroinvertebrate community structure, expressed as SPEARpesticides, and caused, on average, threefold increased insecticide tolerance in G. pulex as a result of adaptation. The toxic pressure derived from body burden and from water samples similarly explained the change in community structure (68% and 64%). However, the increased tolerance of G. pulex to pesticides was better explained by the toxicity derived from body burden (70%) than by the toxicity from water samples (53%). We conclude that the internal body burden of macroinvertebrates is suitable to assess the overall pesticide exposure and effects in agricultural streams.
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Optimizing bulk milk dioxin monitoring based on costs and effectiveness.
Lascano-Alcoser, V H; Velthuis, A G J; van der Fels-Klerx, H J; Hoogenboom, L A P; Oude Lansink, A G J M
2013-07-01
Dioxins are environmental pollutants, potentially present in milk products, which have negative consequences for human health and for the firms and farms involved in the dairy chain. Dioxin monitoring in feed and food has been implemented to detect their presence and estimate their levels in food chains. However, the costs and effectiveness of such programs have not been evaluated. In this study, the costs and effectiveness of bulk milk dioxin monitoring in milk trucks were estimated to optimize the sampling and pooling monitoring strategies aimed at detecting at least 1 contaminated dairy farm out of 20,000 at a target dioxin concentration level. Incidents of different proportions, in terms of the number of contaminated farms, and concentrations were simulated. A combined testing strategy, consisting of screening and confirmatory methods, was assumed as well as testing of pooled samples. Two optimization models were built using linear programming. The first model aimed to minimize monitoring costs subject to a minimum required effectiveness of finding an incident, whereas the second model aimed to maximize the effectiveness for a given monitoring budget. Our results show that a high level of effectiveness is possible, but at high costs. Given specific assumptions, monitoring with 95% effectiveness to detect an incident of 1 contaminated farm at a dioxin concentration of 2 pg of toxic equivalents/g of fat [European Commission's (EC) action level] costs €2.6 million per month. At the same level of effectiveness, a 73% cost reduction is possible when aiming to detect an incident where 2 farms are contaminated at a dioxin concentration of 3 pg of toxic equivalents/g of fat (EC maximum level). With a fixed budget of €40,000 per month, the probability of detecting an incident with a single contaminated farm at a dioxin concentration equal to the EC action level is 4.4%. This probability almost doubled (8.0%) when aiming to detect the same incident but with a dioxin concentration equal to the EC maximum level. This study shows that the effectiveness of finding an incident depends not only on the ratio at which, for testing, collected truck samples are mixed into a pooled sample (aiming at detecting certain concentration), but also the number of collected truck samples. In conclusion, the optimal cost-effective monitoring depends on the number of contaminated farms and the concentration aimed at detection. The models and study results offer quantitative support to risk managers of food industries and food safety authorities. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
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Correlation of Noncancer Benchmark Doses in Short- and Long-Term Rodent Bioassays.
Kratchman, Jessica; Wang, Bing; Fox, John; Gray, George
2018-05-01
This study investigated whether, in the absence of chronic noncancer toxicity data, short-term noncancer toxicity data can be used to predict chronic toxicity effect levels by focusing on the dose-response relationship instead of a critical effect. Data from National Toxicology Program (NTP) technical reports have been extracted and modeled using the Environmental Protection Agency's Benchmark Dose Software. Best-fit, minimum benchmark dose (BMD), and benchmark dose lower limits (BMDLs) have been modeled for all NTP pathologist identified significant nonneoplastic lesions, final mean body weight, and mean organ weight of 41 chemicals tested by NTP between 2000 and 2012. Models were then developed at the chemical level using orthogonal regression techniques to predict chronic (two years) noncancer health effect levels using the results of the short-term (three months) toxicity data. The findings indicate that short-term animal studies may reasonably provide a quantitative estimate of a chronic BMD or BMDL. This can allow for faster development of human health toxicity values for risk assessment for chemicals that lack chronic toxicity data. © 2017 Society for Risk Analysis.
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Armstrong, Eliana S; Mikulca, Janelle A; Cloutier, Daniel J; Bliss, Caleb A; Steenbergen, Judith N
2016-11-25
Fluoroquinolones are a guideline-recommended therapy for complicated urinary tract infections, including pyelonephritis. Elevated drug concentrations of fluoroquinolones in the urine and therapy with high-dose levofloxacin are believed to overcome resistance and effectively treat infections caused by resistant bacteria. The ASPECT-cUTI phase 3 clinical trial (ClinicalTrials.gov, NCT01345929 and NCT01345955 , both registered April 28, 2011) provided an opportunity to test this hypothesis by examining the clinical and microbiological outcomes of high-dose levofloxacin treatment by levofloxacin minimum inhibitory concentration. Patients were randomly assigned 1:1 to ceftolozane/tazobactam (1.5 g intravenous every 8 h) or levofloxacin (750 mg intravenous once daily) for 7 days of therapy. The ASPECT-cUTI study provided data on 370 patients with at least one isolate of Enterobacteriaceae at baseline who were treated with levofloxacin. Outcomes were assessed at the test-of-cure (5-9 days after treatment) and late follow-up (21-42 days after treatment) visits in the microbiologically evaluable population (N = 327). Test-of-cure clinical cure rates above 90% were observed at minimum inhibitory concentrations ≤4 μg/mL. Microbiological eradication rates were consistently >90% at levofloxacin minimum inhibitory concentrations ≤0.06 μg/mL. Lack of eradication of causative pathogens at the test-of-cure visit increased the likelihood of relapse by the late follow-up visit. Results from this study do not support levofloxacin therapy for complicated urinary tract infections caused by organisms with levofloxacin minimum inhibitory concentrations ≥4 μg/mL. ClinicalTrials.gov, NCT01345929 and NCT01345955.
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Hepatic concentrations of copper and other metals in dogs with and without chronic hepatitis.
Cedeño, Y; López-Alonso, M; Miranda, M
2016-12-01
Defects in copper metabolism have been described in several dog breeds, and recently, it has been suggested that changes in other essential trace elements could be involved in the pathogenesis of hepatic disease. This study measured hepatic copper accumulation and its interactions with other essential trace and toxic metals in dogs diagnosed with chronic hepatitis. Liver samples of 20 chronic hepatitis and 20 healthy dogs were collected. Samples were acid digested, and essential metals (cobalt, copper, iron, manganese, molibdenum, selenium and zinc) and toxic metals (arsenic, cadmium, mercury and lead) were analysed by inductively-coupled plasma mass spectrometry. Copper concentrations were significantly higher in dogs affected by hepatic disease than in controls. Dogs having chronic hepatitis with liver copper concentration greater than 100 mg/kg wet weight showed statistically higher cobalt, manganese and zinc concentrations than dogs having chronic hepatitis with liver copper concentrations less than 100 mg/kg wet weight and controls. Toxic metal concentrations were low - in all cases below the threshold associated with toxicity in dogs. Dogs with chronic hepatitis not only have increased concentrations of copper in the liver but also increased concentrations of cobalt, manganese and zinc; measurement of these elements may perhaps aid in diagnosis of liver disease in dogs. © 2016 British Small Animal Veterinary Association.
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MODULATING STORM DRAIN FLOWS TO REDUCE STREAM POLLUTANT CONCENTRATIONS
Pathogen and toxic chemical concentrations above the chemical and toxicity water quality standards in creeks and rivers pose risks to human health and aquatic ecosystems. Storm drains discharging into these watercourses often contribute significantly to elevating pollutant concen...
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Effect of dissolved aromatic hydrocarbons on the growth of marine bacteria in batch culture.
Calder, J A; Lader, J H
1976-01-01
Dissolved aromatic hydrocarbons were found to decrease growth rate and maximum cell density of marine bacteria in batch cultures. The magnitude of the decrement was observed to be a function of concentration of the hydrocarbon and inherent toxicity. The inherent toxicity was observed to increase inversely with solubility such that naphthalene at 100 muM concentration demonstrated a toxic effect similar to benzopyrene at 0.02 muM. A partial oxidation product of naphthalene was found to be more effective in decreasing growth parameters than naphthalene at equivalent concentrations and to cause complete cessation of growth at the higher concentrations permitted by its polar structure. PMID:970939
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Pesticide toxicity index for freshwater aquatic organisms, 2nd edition
Munn, Mark D.; Gilliom, Robert J.; Moran, Patrick W.; Nowell, Lisa H.
2006-01-01
The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program is designed to assess current water-quality conditions, changes in water quality over time, and the effects of natural and human factors on water quality for the Nation's streams and ground-water resources. For streams, one of the most difficult parts of the assessment is to link chemical conditions to effects on aquatic biota, particularly for pesticides, which tend to occur in streams as complex mixtures with strong seasonal patterns. A Pesticide Toxicity Index (PTI) was developed that combines pesticide exposure of aquatic biota (measured concentrations of pesticides in stream water) with acute toxicity estimates (standard endpoints from laboratory bioassays) to produce a single index value for a sample or site. The development of the PTI was limited to pesticide compounds routinely measured in NAWQA studies and to toxicity data readily available from existing databases. Qualifying toxicity data were found for one or more types of test organisms for 124 of the 185 pesticide compounds measured in NAWQA samples, but with a wide range of available bioassays per compound (1 to 232). In the databases examined, there were a total of 3,669 bioassays for the 124 compounds, including 398 48-hour EC50 values (concentration at which 50 percent of test organisms exhibit a sublethal response) for freshwater cladocerans, 699 96-hour LC50 values (concentration lethal to 50 percent of test organisms) for freshwater benthic invertebrates, and 2,572 96-hour LC50 values for freshwater fish. The PTI for a particular sample is the sum of toxicity quotients (measured concentration divided by the median toxicity concentration from bioassays) for each detected pesticide, and thus, is based on the concentration addition model of pesticide toxicity. The PTI can be calculated for specific groups of pesticides and for specific taxonomic groups. Although the PTI does not determine whether water in a sample is toxic to aquatic organisms, its values can be used to rank or compare the toxicity of samples or sites on a relative basis for use in further analysis or additional assessments. The PTI approach may be useful as a basis for comparing the potential significance of pesticides in different streams on a common basis, for evaluating relations between pesticide exposure and observed biological conditions, and for prioritizing where further studies are most needed.
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Acute toxicity and associated mechanisms of four strobilurins in algae.
Liu, Xiaoxu; Wang, Yu; Chen, Hao; Zhang, Junli; Wang, Chengju; Li, Xuefeng; Pang, Sen
2018-06-01
Strobilurins have been reported highly toxic to non-target aquatic organisms but few illustrated how they cause toxic effects on algae. This study investigated the acute toxicity of Kresoxim-methy (KRE), Pyraclostrobin (PYR), Trifloxystrobin (TRI) and Picoxystrobin (PIC) on two algae and their toxicity mechanisms. Four strobilurins showed lower toxic effects on Chlorella pyrenoidsa but higher on Chlorella vulgaris. bc1 complex activities in C. vulgaris were significantly inhibited by all strobilurins, suggesting bc 1 complex might be the target of strobilurin toxicity in algae. Moreover, SOD, CAT and POD activities were significantly up-regulated by all doses of KRE, PYR and PIC. In contrast, low concentrations of TRI stimulated SOD and POD activities but highest concentration significantly inhibited those activities. Comet assays showed damaged DNA in C. vulgaris by four strobulirins, suggesting their potential genotoxic threats to algae. The results illustrated acute toxicity by strobulirins on algae and their possible toxicity mechanisms. Copyright © 2018 Elsevier B.V. All rights reserved.
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Susceptibility of Candida glabrata biofilms to echinocandins: alterations in the matrix composition.
Rodrigues, Célia F; Rodrigues, Maria Elisa; Henriques, Mariana
2018-05-25
Candidiases are the most recurrent fungal infections, especially among immunosuppressed patients. Although Candida albicans is still the most widespread isolated species, non-Candida albicans Candida species have been increasing. The goal of this work was to determine the susceptibility of C. glabrata biofilms to echinocandins and to evaluate their effect on the biofilm matrix composition, comparing the results with other Candida species. Drug susceptibilities were assessed through the determination of minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC) and minimum biofilm eradication concentration (MBEC) of caspofungin (Csf) and micafugin (Mcf). The β-1,3 glucans content of the matrices was assessed after contact with the drugs. The data suggest that, generally, after contact with echinocandins, the concentration of β-1,3 glucans increased. These adjustments in the matrix composition of C. glabrata biofilms and the chemical differences between Csf and Mcf, seem responsible and may determine the effectivity of the drug responses.
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Mount, David R.; Erickson, Russell J.; Highland, Terry L.; Hockett, J. Russell; Hoff, Dale J.; Jenson, Correne T.; Norberg-King, Teresa J.; Peterson, Kira N.; Polaske, Zach; Wisniewski, Stephanie
2018-01-01
The ions Na+, K+, Ca2+, Mg2+, Cl−, SO42−, and HCO3−/CO32− (referred to here as “major ions”) are present in all fresh waters and are physiologically required by aquatic organisms, but can increase to harmful levels from a variety of anthropogenic activities. It is also known that the toxicities of major ion salts can vary depending on the concentrations of other ions, and understanding these relationships is key to establishing appropriate environmental limits. In this paper we present a series of experiments with Ceriodaphnia dubia to evaluate the acute toxicity of twelve major ion salts and to determine how toxicity of these salts varies as a function of background water chemistry. All salts except CaSO4 and CaCO3 were acutely toxic below saturation, with the lowest LC50s found for K salts. All ten salts that showed toxicity also showed some degree of reduced toxicity as the ionic content of the background water increased. Experiments that independently varied Ca:Mg ratio, Na:K ratio, Cl:SO4 ratio, and alkalinity/pH demonstrated that Ca concentration was the primary factor influencing the toxicities of Na and Mg salts, while the toxicities of K salts were primarily influenced by the concentration of Na. These experiments also indicated multiple mechanisms of toxicity and suggested important aspects of dosimetry: the toxicities of K, Mg, and Ca salts were best related to the chemical activity of the cation, while the toxicities of Na salts also reflected an influence of the anions and were well correlated with osmolarity. Understanding these relationships between major ion toxicity and background water chemistry should aid in the development of sensible risk assessment and regulatory standards. PMID:27167636
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Toxicity of herbicides in highway runoff.
Huang, Xinjiang; Fong, Stephanie; Deanovic, Linda; Young, Thomas M
2005-09-01
Previous field monitoring at two highway sites found highway-applied herbicides in storm water runoff at maximum concentrations ranging from 10 microg/L for glyphosate and diuron to as high as 200 microg/L for oryzalin. To determine whether these herbicides at these concentrations can cause any toxicity to aquatic organisms, a standard toxicity study was conducted. Storm water was collected along Highway 37, Sonoma County, California, USA, and the herbicides isoxaben, oryzalin, diuron, clopyralid, and glyphosate were spiked into the storm water at the highest concentrations observed during the five previous field-monitoring campaigns. Three different toxicity studies were conducted and the results showed the following: No significant reduction in reproduction or increase in mortality relative to the control for an 8-d Ceriodaphnia (water flea) toxicity test; no significant increase in mortality or decrease in biomass compared to the control during a 7-d Pimephales (fish) toxicity test; and, in a 96-h Selenastrum (algae) toxicity test, both the 10-microg/L diuron treatment and the combined 50-microg/L isoxaben plus 200-microg/L oryzalin treatment produced significant (p < 0.05) reductions in algal growth compared to the controls, although the 30-microg/L clopyralid or 10-microg/L glyphosate treatments did not exhibit any toxic effects.
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Effects of water quality parameters on boron toxicity to Ceriodaphnia dubia.
Dethloff, Gail M; Stubblefield, William A; Schlekat, Christian E
2009-07-01
The potential modifying effects of certain water quality parameters (e.g., hardness, alkalinity, pH) on the acute toxicity of boron were tested using a freshwater cladoceran, Ceriodaphnia dubia. By comparison, boron acute toxicity was less affected by water quality characteristics than some metals (e.g., copper and silver). Increases in alkalinity over the range tested did not alter toxicity. Increases in water hardness appeared to have an effect with very hard waters (>500 mg/L as CaCO(3)). Decreased pH had a limited influence on boron acute toxicity in laboratory waters. Increasing chloride concentration did not provide a protective effect. Boron acute toxicity was unaffected by sodium concentrations. Median acute lethal concentrations (LC(50)) in natural water samples collected from three field sites were all greater than in reconstituted laboratory waters that matched natural waters in all respects except for dissolved organic carbon. Water effect ratios in these waters ranged from 1.4 to 1.8. In subsequent studies using a commercially available source of natural organic matter, acute toxicity decreased with increased dissolved organic carbon, suggesting, along with the natural water studies, that dissolved organic carbon should be considered further as a modifier of boron toxicity in natural waters where it exceeds 2 mg/L.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Fairey, R.; Roberts, C.; Jacobi, M.
1998-08-01
Sediment quality within San Diego Bay, Mission Bay, and the Tijuana River Estuary of California was investigated as part of an ongoing statewide monitoring effort (Bay Protection and Toxic Cleanup Program). Study objectives were to determine the incidence, spatial patterns, and spatial extent of toxicity in sediments and porewater; the concentration and distribution of potentially toxic anthropogenic chemicals; and the relationships between toxicity and chemical concentrations. Rhepoxynius abronius survival bioassays, grain size, and total organic carbon analyses were performed on 350 sediment samples. Strongylocentrotus purpuratus development bioassays were performed on 164 pore-water samples. Toxicity was demonstrated throughout the San Diegomore » Bay region, with increased incidence and concordance occurring in areas of industrial and shipping activity. Trace metal and trace synthetic organic analyses were performed on 229 samples. Copper, zinc, mercury, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and chlordane were found to exceed ERM (effects range median) or PEL (probable effects level) sediment quality guidelines and were considered the six major chemicals or chemical groups of concern. Statistical analysis of the relationships between amphipod toxicity, bulk phase sediment chemistry, and physical parameters demonstrated few significant linear relationships. Significant differences in chemical levels were found between toxic and nontoxic responses using multivariate and univariate statistics. Potential sources of anthropogenic chemicals were discussed.« less
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Xiao, Yinlong; Peijnenburg, Willie J G M; Chen, Guangchao; Vijver, Martina G
2018-01-01
Toxicity of metallic nanoparticle suspensions (NP (total) ) is generally assumed to result from the combined effect of the particles present in suspensions (NP (particle) ) and their released ions (NP (ion) ). Evaluation and consideration of how water chemistry affects the particle-specific toxicity of NP (total) are critical for environmental risk assessment of nanoparticles. In this study, it was found that the toxicity of Cu NP (particle) to Daphnia magna, in line with the trends in toxicity for Cu NP (ion) , decreased with increasing pH and with increasing concentrations of divalent cations and dissolved organic carbon (DOC). Without the addition of DOC, the toxicity of Cu NP (total) to D. magna at the LC50 was driven mainly by Cu NP (ion) (accounting for ≥53% of the observed toxicity). However, toxicity of Cu NP (total) in the presence of DOC at a concentration ranging from 5 to 50mg C/L largely resulted from the NP (particle) (57%-85%), which could be attributable to the large reduction of the concentration of Cu NP (ion) and the enhancement of the stability of Cu NP (particle) when DOC was added. Our results indicate that water chemistry needs to be explicitly taken into consideration when evaluating the role of NP (particle) and NP (ion) in the observed toxicity of NP (total) . Copyright © 2017 Elsevier B.V. All rights reserved.
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Approaching the Minimum Thermal Conductivity in Rhenium-Substituted Higher Manganese Silicides
DOE Office of Scientific and Technical Information (OSTI.GOV)
Chen, Xi; Girard, S. N.; Meng, F.
Higher manganese silicides (HMS) made of earth-abundant and non-toxic elements are regarded as promising p-type thermoelectric materials because their complex crystal structure results in low lattice thermal conductivity. It is shown here that the already low thermal conductivity of HMS can be reduced further to approach the minimum thermal conductivity via partial substitu- tion of Mn with heavier rhenium (Re) to increase point defect scattering. The solubility limit of Re in the obtained RexMn1 xSi1.8 is determined to be about x = 0.18. Elemental inhomogeneity and the formation of ReSi1.75 inclusions with 50 200 nm size are found within themore » HMS matrix. It is found that the power factor does not change markedly at low Re content of x 0.04 before it drops considerably at higher Re contents. Compared to pure HMS, the reduced lattice thermal conductivity in RexMn1 xSi1.8 results in a 25% increase of the peak figure of merit ZT to reach 0.57 0.08 at 800 K for x = 0.04. The suppressed thermal conductivity in the pure RexMn1 xSi1.8 can enable further investigations of the ZT limit of this system by exploring different impurity doping strategies to optimize the carrier concentration and power factor.« less
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NASA Astrophysics Data System (ADS)
Nthunya, Lebea N.; Masheane, Monaheng L.; Malinga, Soraya P.; Nxumalo, Edward N.; Mamba, Bhekie B.; Mhlanga, Sabelo D.
2017-08-01
This study was conducted to determine the presence and levels of toxic metals on selected water sources in a rural community in Lochiel, South Africa. Collection of water samples from identified drinking water sources (open wells, community tanks, water treatment works and boreholes) was done in all seasons of the year (winter, spring, summer and autumn) between 2014 and 2015. The concentrations of identified toxic metals (cobalt, chromium, copper, lead, zinc, manganese and iron) were measured using ICP-OES. Some water sources were found to contain concentrations of toxic metals at levels slightly higher than USEPA, WHO and SANS241 set limits (e.g. manganese and cobalt), while others were found to be within the acceptable limits. This suggested that the residents residing in locations that have water sources containing toxic metals at the concentrations above the set limits are at risk and susceptible to suffer diseases caused by these toxic metals. The side effects of the metals may not be acute; however prolonged exposure to the toxic metals may result in detrimental effects since they are known to bioaccumulate in the body.
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Hooten, Russell L.; Carr, R. Scott
1998-01-01
An acute (96 h) pore-water toxicity test protocol using germination and growth of Ulva fasciatazoospores as endpoints was developed to test the toxicity of marine and estuarine sediment pore-water samples. Tests with an organic toxicant (sodium dodecyl sulfate; SDS), three metals (Cd, Cu, and Zn), and ammonia (NH3) were conducted to determine zoospore sensitivity. Zoospore germination and gametophyte growth were as sensitive to SDS as sea urchin (Arbacia punctulata) fertilization and embryological development. Zoospore sensitivity to metals was greater than or comparable to that of adult macroalgae. Zoospores were less sensitive to NH3than were other commonly used toxicity test organisms. Test results using this algal assay with sediment pore-water samples with high NH3 concentrations were compared with results from sea urchin fertilization and embryological development tests for the same samples. Ulva fasciatazoospore germination was not affected by samples with high NH3 concentrations that were toxic in both sea urchin tests. Zoospore tolerance of NH3 and sensitivity to other contaminants indicate that their response may be useful in toxicity identification evaluation studies with pore-water samples that contain high concentrations of unionized NH3.
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Waalewijn-Kool, Pauline L; Diez Ortiz, Maria; van Straalen, Nico M; van Gestel, Cornelis A M
2013-07-01
To assess the effect of long-term dissolution on bioavailability and toxicity, triethoxyoctylsilane coated and uncoated zinc oxide nanoparticles (ZnO-NP), non-nano ZnO and ZnCl2 were equilibrated in natural soil for up to twelve months. Zn concentrations in pore water increased with time for all ZnO forms but peaked at intermediate concentrations of ZnO-NP and non-nano ZnO, while for coated ZnO-NP such a clear peak only was seen after 12 months. Dose-related increases in soil pH may explain decreased soluble Zn levels due to fixation of Zn released from ZnO at higher soil concentrations. At T = 0 uncoated ZnO-NP and non-nano ZnO were equally toxic to the springtail Folsomia candida, but not as toxic as coated ZnO-NP, and ZnCl2 being most toxic. After three months equilibration toxicity to F. candida was already reduced for all Zn forms, except for coated ZnO-NP which showed reduced toxicity only after 12 months equilibration. Copyright © 2013 Elsevier Ltd. All rights reserved.
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Blood harmane, blood lead, and severity of hand tremor: evidence of additive effects.
Louis, Elan D; Factor-Litvak, Pam; Gerbin, Marina; Slavkovich, Vesna; Graziano, Joseph H; Jiang, Wendy; Zheng, Wei
2011-03-01
Tremor is a widespread phenomenon in human populations. Environmental factors are likely to play an etiological role. Harmane (1-methyl-9H-pyrido[3,4-β]indole) is a potent tremor-producing β-carboline alkaloid. Lead is another tremor-producing neurotoxicant. The effects of harmane and lead with respect to tremor have been studied in isolation. We tested the hypothesis that tremor would be particularly severe among individuals who had high blood concentrations of both of these toxicants. Blood concentrations of harmane and lead were each quantified in 257 individuals (106 essential tremor cases and 151 controls) enrolled in an environmental epidemiological study. Total tremor score (range = 0-36) was a clinical measure of tremor severity. The total tremor score ranged from 0 to 36, indicating that a full spectrum of tremor severities was captured in our sample. Blood harmane concentration correlated with total tremor score (p = 0.007), as did blood lead concentration (p = 0.045). The total tremor score was lowest in participants with both low blood harmane and lead concentrations (8.4 ± 8.2), intermediate in participants with high concentrations of either toxicant (10.5 ± 9.8), and highest in participants with high concentrations of both toxicants (13.7 ± 10.4) (p=0.01). Blood harmane and lead concentrations separately correlated with total tremor scores. Participants with high blood concentrations of both toxicants had the highest tremor scores, suggesting an additive effect of these toxicants on tremor severity. Given the very high population prevalence of tremor disorders, identifying environmental determinants is important for primary disease prevention. Copyright © 2010 Elsevier Inc. All rights reserved.
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Blood Harmane, Blood Lead, and Severity of Hand Tremor: Evidence of Additive Effects
Louis, Elan D.; Factor-Litvak, Pam; Gerbin, Marina; Slavkovich, Vesna; Graziano, Joseph H; Jiang, Wendy; Zheng, Wei
2010-01-01
Background Tremor is a widespread phenomenon in human populations. Environmental factors are likely to play an etiological role. Harmane (1-methyl-9H-pyrido[3,4-β]indole) is a potent tremor-producing β-carboline alkaloid. Lead is another tremor-producing neurotoxicant. The effects of harmane and lead with respect to tremor have been studied in isolation. Objectives We tested the hypothesis that tremor would be particularly severe among individuals who had high blood concentrations of both of these toxicants. Methods Blood concentrations of harmane and lead were each quantified in 257 individuals (106 essential tremor cases and 151 controls) enrolled in an environmental epidemiological study. Total tremor score (range = 0 – 36) was a clinical measure of tremor severity. Results The total tremor score ranged from 0 – 36, indicating that a full spectrum of tremor severities was captured in our sample. Blood harmane concentration correlated with total tremor score (p = 0.007), as did blood lead concentration (p = 0.045). The total tremor score was lowest in participants with both low blood harmane and lead concentrations (8.4 ± 8.2), intermediate in participants with high concentrations of either toxicant (10.5 ± 9.8), and highest in participants with high concentrations of both toxicants (13.7 ± 10.4)(p = 0.01). Conclusions Blood harmane and lead concentrations separately correlated with total tremor scores. Participants with high blood concentrations of both toxicants had the highest tremor scores, suggesting an additive effect of these toxicants on tremor severity. Given the very high population prevalence of tremor disorders, identifying environmental determinants is important for primary disease prevention. PMID:21145352
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Acute toxicity prediction to threatened and endangered ...
Evaluating contaminant sensitivity of threatened and endangered (listed) species and protectiveness of chemical regulations often depends on toxicity data for commonly tested surrogate species. The U.S. EPA’s Internet application Web-ICE is a suite of Interspecies Correlation Estimation (ICE) models that can extrapolate species sensitivity to listed taxa using least-squares regressions of the sensitivity of a surrogate species and a predicted taxon (species, genus, or family). Web-ICE was expanded with new models that can predict toxicity to over 250 listed species. A case study was used to assess protectiveness of genus and family model estimates derived from either geometric mean or minimum taxa toxicity values for listed species. Models developed from the most sensitive value for each chemical were generally protective of the most sensitive species within predicted taxa, including listed species, and were more protective than geometric means models. ICE model estimates were compared to HC5 values derived from Species Sensitivity Distributions for the case study chemicals to assess protectiveness of the two approaches. ICE models provide robust toxicity predictions and can generate protective toxicity estimates for assessing contaminant risk to listed species. Reporting on the development and optimization of ICE models for listed species toxicity estimation
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Hayat, Sikander; Chughtai, Muhammad Ismail; Ansari, Tariq Mahmood; Kamal, Ghulam Mustafa
2012-04-01
A study was carried out to investigate the concentrations of macro-elements (Na(+), K(+) and Mg(+2)) in twelve commercially available pharmaceutical preparations used as sex stimulant, by Atomic Absorption Spectrophotometer. A wet digestion method was adopted to prepare the samples. The results indicated that sodium concentration was maximum (3702 ± 29 μg g(-1)) in LB and minimum (495 ± 06 μg g(-1)) in H-E-H. Potassium concentration was maximum (6337 ± 13 μg g(-1)) in NBA while minimum (150 ± 06 μg g(-1)) in ZGRA. Magnesium concentration was maximum in V-100 (9226 ± 11 μg g(-1)) and minimum in FGRA (1194 ± 25 μg g(-1)). The concentration of macro-elements in the imported herbal preparations was in the order of Mg
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Antiviral activity of Quercus persica L.: High efficacy and low toxicity
Karimi, Ali; Moradi, Mohammad-Taghi; Saeedi, Mojtaba; Asgari, Sedigheh; Rafieian-kopaei, Mahmoud
2013-01-01
Background: Drug-resistant strain of Herpes simplex virus type 1 (HSV-I) has increased the interest in the use of natural substances. Aims: This study was aimed to determine minimum inhibitory concentration of hydroalchoholic extract of a traditionally used herbal plant, Quercus persica L., on HSV-1 replication on baby hamster kidney (BHK) cells. Setting: The study was conducted in Shahrekord University of Medical Sciences, Iran. Design: This was an experimental study. Materials and Methods: BHK cells were grown in monolayer culture with Dulbecco's modified Eagle's medium (DMEM) supplemented with 5% fetal calf serum and plated onto 48-well culture plates. Fifty percent cytotoxic concentration (CC50%) of Q. persica L. on BHK cells was determined. Subsequently, 50% inhibitory concentration (IC50%) of the extract on replication of HSV-1 both in interacellular and exteracellular cases was assessed. Statistical Analysis: Statistic Probit model was used for statistical analysis. The dose-dependent effect of antiviral activity of the extracts was determined by linear regression. Results: Q. persica L. had no cytotoxic effect on this cell line. There was significant relationship between the concentration of the extract and cell death (P<0.01). IC50s of Q. persica L. on HSV-1, before and after attachment to BHK cells were 1.02 and 0.257 μg/mL, respectively. There was significant relationship between the concentration of this extract and inhibition of cytopathic effect (CPE) (P<0.05). Antioxidant capacity of the extract was 67.5%. Conclusions: The hydroalchoholic extract of Q. persica L. is potentially an appropriate and promising anti herpetic herbal medicine. PMID:24516836
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Geochemistry and potential environmental impact of the mine tailings at Rosh Pinah, southern Namibia
NASA Astrophysics Data System (ADS)
Nejeschlebová, L.; Sracek, O.; Mihaljevič, M.; Ettler, V.; Kříbek, B.; Knésl, I.; Vaněk, A.; Penížek, V.; Dolníček, Z.; Mapani, B.
2015-05-01
Mine tailings at Rosh Pinah located in semiarid southern Namibia were investigated by the combination of mineralogical methods and leaching using water and simulated gastric solution. They are well-neutralized with leachate pH > 7 and neutralization potential ratios (NPR) up to 4. Neutralization is mainly due to abundant Mn-rich dolomite in the matrix. Concentrations of released contaminants in water leachate follow the order Zn > Pb > Cu > As. Relatively high leached concentrations of Zn and partly also of Pb are caused by their link to relatively soluble carbonates and Mn-oxyhydroxides. In contrast, As is almost immobile by binding into Fe-oxyhydroxides, which are resistant to dissolution. Barium is released by the dissolution of Ba-carbonate (norsethite) and precipitates in sulfate-rich pore water as barite. Dissolved concentrations in neutral mine drainage water collected in the southern pond are low, but when total concentrations including colloidal fraction are taken into account, more than 70% of Zn is in colloidal form. Groundwater upgradient of the mine tailings is of poor quality and there seems to be no negative impact on groundwater downgradient from mine tailings. Contaminant concentrations in simulated gastric leachates are in the order Ba > Pb > Zn > Cu > As with a maximum gastric bioaccessibility of 86.6% for Ba and a minimum of 3.3% for As. These results demonstrate that total contaminant content and toxicity in the solid phase are poor predictors of risk, and therefore mineralogical and bioavailability/bioaccessibility studies are necessary for evaluation of contaminant environmental impact.
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Manganelli, Maura; Scardala, Simona; Stefanelli, Mara; Vichi, Susanna; Mattei, Daniela; Bogialli, Sara; Ceccarelli, Piegiorgio; Corradetti, Ernesto; Petrucci, Ines; Gemma, Simonetta; Testai, Emanuela; Funari, Enzo
2010-03-01
Increasing concern for human health related to cyanotoxin exposure imposes the identification of pattern and level of exposure; however, current monitoring programs, based on cyanobacteria cell counts, could be inadequate. An integrated approach has been applied to a small lake in Italy, affected by Planktothrix rubescens blooms, to provide a scientific basis for appropriate monitoring program design. The cyanobacterium dynamic, the lake physicochemical and trophic status, expressed as nutrients concentration and recycling rates due to bacterial activity, the identification/quantification of toxic genotype and cyanotoxin concentration have been studied. Our results indicate that low levels of nutrients are not a marker for low risk of P. rubescens proliferation and confirm that cyanobacterial density solely is not a reliable parameter to assess human exposure. The ratio between toxic/non-toxic cells, and toxin concentrations, which can be better explained by toxic population dynamic, are much more diagnostic, although varying with time and environmental conditions. The toxic fraction within P. rubescens population is generally high (30-100%) and increases with water depth. The ratio toxic/non-toxic cells is lowest during the bloom, suggesting a competitive advantage for non-toxic cells. Therefore, when P. rubescens is the dominant species, it is important to analyze samples below the thermocline, and quantitatively estimate toxic genotype abundance. In addition, the identification of cyanotoxin content and congeners profile, with different toxic potential, are crucial for risk assessment. Copyright 2009 Elsevier Ltd. All rights reserved.
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Jurado, Encarnación; Fernández-Serrano, Mercedes; Núñez-Olea, Josefa; Lechuga, Manuela
2009-09-01
In this paper a study was made of the biodegradation of a non-ionic surfactant, a nonylphenol polyethoxylate, in biodegradability tests by monitoring the residual surfactant matter. The influence of the concentration on the extent of primary biodegradation, the toxicity of biodegradation metabolites, and the kinetics of degradation were also determined. The primary biodegradation was studied at different initial concentrations: 5, 25 and 50 mg/L, (at sub-and supra-critical micelle concentration). The NPEO used in this study can be considered biodegradable since the primary biodegradation had already taken place (a biodegradation greater than 80% was found for the different initial concentration tested). The initial concentration affected the shape of the resulting curve, the mean biodegradation rate and the percentage of biodegradation reached (99% in less than 8 days at 5 mg/L, 98% in less than 13 days at 25 mg/L and 95% in 14 days at 50 mg/L). The kinetic model of Quiroga and Sales (1991) was applied to predict the biodegradation of the NPEO. The toxicity value was measured as EC(20) and EC(50). In addition, during the biodegradation process of the surfactant a toxicity analysis was made of the evolution of metabolites generated, confirming that the subproducts of the biodegradation process were more toxic than the original.
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Ricart, Marta; Guasch, Helena; Alberch, Mireia; Barceló, Damià; Bonnineau, Chloé; Geiszinger, Anita; Farré, Marinel la; Ferrer, Josep; Ricciardi, Francesco; Romaní, Anna M; Morin, Soizic; Proia, Lorenzo; Sala, Lluís; Sureda, David; Sabater, Sergi
2010-11-15
Triclosan is a commonly used bactericide that survives several degradation steps in WWTP (wastewater treatment plants) and potentially reaches fluvial ecosystems. In Mediterranean areas, where water scarcity results in low dilution capacity, the potential environmental risk of triclosan is high. A set of experimental channels was used to examine the short-term effects of triclosan (from 0.05 to 500μgL⁻¹) on biofilm algae and bacteria. Environmentally relevant concentrations of triclosan caused an increase of bacterial mortality with a no effect concentration (NEC) of 0.21μgL⁻¹. Dead bacteria accounted for up to 85% of the total bacterial population at the highest concentration tested. The toxicity of triclosan was higher for bacteria than algae. Photosynthetic efficiency was inhibited with increasing triclosan concentrations (NEC=0.42μgL⁻¹), and non-photochemical quenching mechanisms decreased. Diatom cell viability was also affected with increasing concentrations of triclosan. Algal toxicity may be a result of indirect effects on the biofilm toxicity, but the clear and progressive reduction observed in all the algal-related endpoints suggest the existence of direct effects of the bactericide. The toxicity detected on the co-occurring non-target components of the biofilm community, the capacity of triclosan to survive through WWTP processes and the low dilution capacity that characterizes Mediterranean systems extend the relevance of triclosan toxicity beyond bacteria in aquatic habitats. Copyright © 2010 Elsevier B.V. All rights reserved.
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Comparative Toxicity of Nanoparticulate CuO and ZnO to Soil Bacterial Communities
Rousk, Johannes; Ackermann, Kathrin; Curling, Simon F.; Jones, Davey L.
2012-01-01
The increasing industrial application of metal oxide Engineered Nano-Particles (ENPs) is likely to increase their environmental release to soils. While the potential of metal oxide ENPs as environmental toxicants has been shown, lack of suitable control treatments have compromised the power of many previous assessments. We evaluated the ecotoxicity of ENP (nano) forms of Zn and Cu oxides in two different soils by measuring their ability to inhibit bacterial growth. We could show a direct acute toxicity of nano-CuO acting on soil bacteria while the macroparticulate (bulk) form of CuO was not toxic. In comparison, CuSO4 was more toxic than either oxide form. Unlike Cu, all forms of Zn were toxic to soil bacteria, and the bulk-ZnO was more toxic than the nano-ZnO. The ZnSO4 addition was not consistently more toxic than the oxide forms. Consistently, we found a tight link between the dissolved concentration of metal in solution and the inhibition of bacterial growth. The inconsistent toxicological response between soils could be explained by different resulting concentrations of metals in soil solution. Our findings suggested that the principal mechanism of toxicity was dissolution of metal oxides and sulphates into a metal ion form known to be highly toxic to bacteria, and not a direct effect of nano-sized particles acting on bacteria. We propose that integrated efforts toward directly assessing bioavailable metal concentrations are more valuable than spending resources to reassess ecotoxicology of ENPs separately from general metal toxicity. PMID:22479561
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Composition and antimicrobial properties of essential oils of four Mediterranean Lamiaceae.
Panizzi, L; Flamini, G; Cioni, P L; Morelli, I
1993-08-01
Essential oils from Satureja montana L., Rosmarinus officinalis L., Thymus vulgaris L., and Calamintha nepeta (L.) Savi, were chemically analysed and their antimicrobial and fungicide activities evaluated on the basis of their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). All four oils have a biotoxic effect, the most active being those from Calamintha and Thymus.
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Fluoroquinolone Treatment and Susceptibility of Isolates From Bacterial Keratitis
Ray, Kathryn J.; Prajna, Lalitha; Srinivasan, Muthiah; Geetha, Manoharan; Karpagam, Rajarathinam; Glidden, David; Oldenburg, Catherine E.; Sun, Catherine Q.; McLeod, Stephen D.; Acharya, Nisha R.; Lietman, Thomas M.
2013-01-01
Objective To analyze the relationship between fluoroquinolone use at presentation and minimum inhibitory concentration in bacterial keratitis. Methods The Steroids for Corneal Ulcers Trial was a randomized, double-masked, placebo-controlled trial assessing the effect of adjunctive topical corticosteroid treatment on outcomes in bacterial keratitis. After presentation, all patients were treated with moxifloxacin hydrochloride, 0.5%. We compare antibiotic use at presentation with minimum inhibitory concentration against moxifloxacin for all isolates. Separate analyses accounted for organism species and fluoroquinolone generation. Results Topical fluoroquinolone use at presentation was reported in 92 of 480 cases (19.2%). Causative organisms in the 480 cases included Streptococcus pneumoniae (247 cases [51.5%]), Pseudomonas aeruginosa (109 cases [22.7%]), and Nocardia species (55 cases [11.5%]). Isolates from patients who reported fluoroquinolone use at presentation had a 2.01-fold–higher minimum inhibitory concentration (95% CI, 1.39-fold to 2.91-fold; P <.001). Fourth-generation fluoroquinolones were associated with a 3.48-fold–higher minimum inhibitory concentration than those isolates that were not exposed to pretreatment at enrollment (95% CI, 1.99-fold to 6.06-fold; P <.001). Conclusion This study provides evidence that prior use of fluoroquinolones is associated with antibiotic resistance. PMID:23307105
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Fluoroquinolone treatment and susceptibility of isolates from bacterial keratitis.
Ray, Kathryn J; Prajna, Lalitha; Srinivasan, Muthiah; Geetha, Manoharan; Karpagam, Rajarathinam; Glidden, David; Oldenburg, Catherine E; Sun, Catherine Q; McLeod, Stephen D; Acharya, Nisha R; Lietman, Thomas M
2013-03-01
To analyze the relationship between fluoroquinolone use at presentation and minimum inhibitory concentration in bacterial keratitis. The Steroids for Corneal Ulcers Trial was a randomized, double-masked, placebo-controlled trial assessing the effect of adjunctive topical corticosteroid treatment on outcomes in bacterial keratitis. After presentation, all patients were treated with moxifloxacin hydrochloride, 0.5%. We compare antibiotic use at presentation with minimum inhibitory concentration against moxifloxacin for all isolates. Separate analyses accounted for organism species and fluoroquinolone generation. Topical fluoroquinolone use at presentation was reported in 92 of 480 cases (19.2%). Causative organisms in the 480 cases included Streptococcus pneumoniae (247 cases [51.5%]), Pseudomonas aeruginosa (109 cases [22.7%]), and Nocardia species (55 cases [11.5%]). Isolates from patients who reported fluoroquinolone use at presentation had a 2.01-fold-higher minimum inhibitory concentration (95% CI, 1.39-fold to 2.91-fold; P < .001). Fourth-generation fluoroquinolones were associated with a 3.48-fold-higher minimum inhibitory concentration than those isolates that were not exposed to pretreatment at enrollment (95% CI, 1.99-fold to 6.06-fold; P < .001). This study provides evidence that prior use of fluoroquinolones is associated with antibiotic resistance. clinicaltrials.gov Identifier: NCT00324168.
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Birds and Dutch elm disease control
DeWitt, J.B.
1958-01-01
Brief, factual review of information on effect of DDT and other insecticides on birds. One program for control of elm disease caused 22% decrease in number of adult birds and 56% mortality of nestlings. Quail fed 3 oz. of DDT per ton of food had 16% reduction in young hatched and 500% increase in defective chicks. Quail fed same dosage during winter and breeding seasons had 30% decrease in fertile eggs and 800% increase in defective chicks. More than 90% of their chicks died in first 6 weeks although fed no insecticide. Almost equally bad results came from feeding Pheasants diets with about 1 oz. DDT per ton. Other common insecticides (chlorinated hydrocarbons) also caused lowered chick survival and higher percentages of crippled chicks. From field data we know that 2 lbs. DDT/acre can affect birds and has even worse effects on cold-blooded animals. Efforts to control elm disease have left as much as 196 lbs. DDT/acre in top 3 inches of soil. Earthworms concentrate DDT in their tissues. Thus the treated areas can be traps for birds and other animals. What can be done? 1) In control of elm disease, use minimum effective amount of insecticide; mist blowers use less than sprayers. 2) Avoid applications during migration and nesting seasons. It has been reported that adequate control can be obtained with dormant sprays and that foliar applications may not be required. Tables of this paper show effects of DDT on reproduction of Quail, relative toxicity to quail of 8 insecticides, and amounts of 7 insecticides required to cause 40% or more decrease in Quail reproduction. These comparisons demonstrate that Aldrin, Endrin, and Dieldrin are 20 to 200 times as toxic as DDT and that Heptachlor and Chlordane are only slightly less toxic than Dieldrin. Methoxychlor and Strobane are less toxic to Quail than is DDT.
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Wilber, William G.; Peters, James G.; Crawford, Charles G.
1979-01-01
A digital model calibrated to conditions in East Fork White River, Bartholomew County, IN, was used to develop alternatives for future waste loadings that would be compatible with Indiana stream water-quality standards defined for two critical hydrologic conditions, summer and winter low flows. The model indicates that benthic-oxygen demand and the headwater concentrations of carbonaceous biochemical-oxygen demand, nitrogenous biochemical-oxygen demand, and dissolved oxygen are the most significant factors affecting the dissolved-oxygen concentration of East Fork White River downstream from the Columbus wastewater-treatment facility. The effect of effluent from the facility on the water quality of East Fork White River was minimal. The model also indicates that, with a benthic-oxygen demand of approximately 0.65 gram per square meter per day, the stream has no additional waste-load assimilative capacity during summer low flows. Regardless of the quality of the Columbus wastewater effluent, the minimum 24-hour average dissolved-oxygen concentration of at least 5 milligrams per liter, the State 's water-quality standard for streams, would not be met. Ammonia toxicity is not a limiting water-quality criterion during summer and winter low flows. During winter low flows, the current carbonaceous biochemical-oxygen demand limits for the Columbus wastewater-treatment facility will not result in violations of the in-stream dissolved-oxygen standard. (USGS)
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A simple headspace equilibration method for measuring dissolved methane
Magen, C; Lapham, L.L.; Pohlman, John W.; Marshall, Kristin N.; Bosman, S.; Casso, Michael; Chanton, J.P.
2014-01-01
Dissolved methane concentrations in the ocean are close to equilibrium with the atmosphere. Because methane is only sparingly soluble in seawater, measuring it without contamination is challenging for samples collected and processed in the presence of air. Several methods for analyzing dissolved methane are described in the literature, yet none has conducted a thorough assessment of the method yield, contamination issues during collection, transport and storage, and the effect of temperature changes and preservative. Previous extraction methods transfer methane from water to gas by either a "sparge and trap" or a "headspace equilibration" technique. The gas is then analyzed for methane by gas chromatography. Here, we revisit the headspace equilibration technique and describe a simple, inexpensive, and reliable method to measure methane in fresh and seawater, regardless of concentration. Within the range of concentrations typically found in surface seawaters (2-1000 nmol L-1), the yield of the method nears 100% of what is expected from solubility calculation following the addition of known amount of methane. In addition to being sensitive (detection limit of 0.1 ppmv, or 0.74 nmol L-1), this method requires less than 10 min per sample, and does not use highly toxic chemicals. It can be conducted with minimum materials and does not require the use of a gas chromatograph at the collection site. It can therefore be used in various remote working environments and conditions.
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Betanzos-Cabrera, Gabriel; Montes-Rubio, Perla Y.; Fabela-Illescas, Héctor E.; Belefant-Miller, Helen; Cancino-Diaz, Juan C.
2015-01-01
Background Polyphenols have received a great deal of attention due to their biological functions. Pomegranate (Punica granatum L.) is a polyphenol-rich fruit. In the past decade, studies testing the antimicrobial activity of pomegranates almost exclusively used solvent extracts instead of fresh pomegranate juice (FPJ). The use of FPJ instead of solvent extracts would reduce toxicity issues while increasing patient acceptance. We established a model to test FPJ as a natural antimicrobial agent. Objective To evaluate the antimicrobial activity of FPJ on clinical isolates of multidrug-resistant Staphylococcus epidermidis strains. Design Sixty strains of S. epidermidis isolated from ocular infections were grown in the presence of FPJ, and minimum inhibitory concentration (MIC) was determined by broth and agar dilution methods. Results FPJ at 20% had a MIC equal to 100% (MIC100%) on all 60 strains tested. This inhibition of FPJ was confirmed by the growth kinetics of a multidrug-resistant strain exposed to different concentrations of FPJ. Additionally, the antimicrobial activity of FPJ was compared against commercial beverages containing pomegranate: Ocean Spray® had a MIC100% at 20%, followed by Del Valle® with a MIC15% at 20% concentration only. The beverages Jumex® and Sonrisa® did not have any antimicrobial activity. FPJ had the highest polyphenol content and antioxidant capacity. Conclusions Overall, FPJ had antimicrobial activity, which might be attributed to its high polyphenol content and antioxidant capacity. PMID:25999265
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Design, synthesis and antibacterial evaluation of honokiol derivatives.
Wu, Bo; Fu, Su-Hong; Tang, Huan; Chen, Kai; Zhang, Qiang; Peng, Ai-Hua; Ye, Hao-Yu; Cheng, Xing-Jun; Lian, Mao; Wang, Zhen-Ling; Chen, Li-Juan
2018-02-15
Staphylococcus aureus is a major and dangerous human pathogen that causes a range of clinical manifestations of varying severity, and is the most commonly isolated pathogen in the setting of skin and soft tissue infections, pneumonia, suppurative arthritis, endovascular infections, foreign-body associated infections, septicemia, osteomyelitis, and toxic shocksyndrome. Honokiol, a pharmacologically active natural compound derived from the bark of Magnolia officinalis, has antibacterial activity against Staphylococcus aureus which provides a great inspiration for the discovery of potential antibacterial agents. Herein, honokiol derivatives were designed, synthesized and evaluated for their antibacterial activity by determining the minimum inhibitory concentration (MIC) against S. aureus ATCC25923 and Escherichia coli ATCC25922 in vitro. 7c exhibited better antibacterial activity than other derivatives and honokiol. The structure-activity relationships indicated piperidine ring with amino group is helpful to improve antibacterial activity. Further more, 7c showed broad spectrum antibacterial efficiency against various bacterial strains including eleven gram-positive and seven gram-negative species. Time-kill kinetics against S. aureus ATCC25923 in vitro revealed that 7c displayed a concentration-dependent effect and more rapid bactericidal kinetics better than linezolid and vancomycin with the same concentration. Gram staining assays of S. aureus ATCC25923 suggested that 7c could destroy the cell walls of bacteria at 1×MIC and 4×MIC. Copyright © 2017. Published by Elsevier Ltd.
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Min, Kyung R.; Galvis, Adriana; Williams, Brandon; Rayala, Ramanjaneyulu; Cudic, Predrag
2017-01-01
ABSTRACT Despite continuous efforts to control cariogenic dental biofilms, very few effective antimicrobial treatments exist. In this study, we characterized the activity of the novel synthetic cyclic lipopeptide 4 (CLP-4), derived from fusaricidin, against the cariogenic pathogen Streptococcus mutans UA159. We determined CLP-4's MIC, minimum bactericidal concentration (MBC), and spontaneous resistance frequency, and we performed time-kill assays. Additionally, we assessed CLP-4's potential to inhibit biofilm formation and eradicate preformed biofilms. Our results demonstrate that CLP-4 has strong antibacterial activity in vitro and is a potent bactericidal agent with low spontaneous resistance frequency. At a low concentration of 5 μg/ml, CLP-4 completely inhibited S. mutans UA159 biofilm formation, and at 50 μg/ml, it reduced the viability of established biofilms by >99.99%. We also assessed CLP-4's cytotoxicity and stability against proteolytic digestion. CLP-4 withstood trypsin or chymotrypsin digestion even after treatment for 24 h, and our toxicity studies showed that CLP-4 effective concentrations had negligible effects on hemolysis and the viability of human oral fibroblasts. In summary, our findings showed that CLP-4 is a potent antibacterial and antibiofilm agent with remarkable stability and low nonspecific cytotoxicity. Hence, CLP-4 is a promising novel antimicrobial peptide with potential for clinical application in the prevention and treatment of dental caries. PMID:28533236
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Phototoxicity assessment of drugs and cosmetic products using E. coli.
Verma, K; Agrawal, N; Misra, R B; Farooq, M; Hans, R K
2008-02-01
A gram negative bacteria Escherichia coli (Dh5alpha strain) was developed as an alternate test system of phototoxicity. Eight drugs (antibiotics) and cosmetic products (eight face creams) were examined for their phototoxicity using this test system. Five known phototoxic compounds were used to validate the test system. UVA-radiation induced phototoxicity of these compounds was tested by agar gel diffusion assay. Decrease in colony forming units (CFU) was taken as an end point of phototoxicity. The phototoxic compounds and antibiotics produced significant reduction in CFU (p<0.001) at 80 microg/ml concentrations under exposure to UVA-radiation (5.4-10.8 J/cm(2)). One face cream was found phototoxic and produced significant decrease in CFU of E. coli at 1.0mg/ml concentration under UVA exposure (10.8 J/cm(2)). The minimum effective concentration of tetracycline and dose of UVA-radiation were also determined by observing growth inhibition of E. coli through disc diffusion assay. The observations suggested that E. coli can be used as an alternative test system for phototoxicity evaluation of chemicals. A battery of test systems is required to conclude the toxic/phototoxic potential of a chemical agent. In view of the speed, easiness, sensitivity and low cost, E. coli is introduced as one of the alternate test system for phototoxicity studies in safety evaluation of various chemical ingredients or formulations used in cosmetics and drugs.
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Comparative Toxicity of Preservatives on Immortalized Corneal and Conjunctival Epithelial Cells
Ahdoot, Michael; Marcus, Edward; Asbell, Penny A.
2009-01-01
Abstract Purpose Nearly all eye drops contain preservatives to decrease contamination. Nonpreservatives such as disodium-ethylene diamine tetra-acetate (EDTA) and phosphate-buffered saline are also regularly added as buffering agents. These components can add to the toxicity of eye drops and cause ocular surface disease. To evaluate the potential toxicity of these common components and their comparative effects on the ocular surface, a tissue culture model utilizing immortalized corneal and conjunctival epithelial cells was utilized. Methods Immortalized human conjunctival and corneal epithelial cells were grown. At confluency, medium was replaced with 100 μL of varying concentrations of preservatives: benzalkonium chloride (BAK), methyl paraben (MP), sodium perborate (SP), chlorobutanol (Cbl), and stabilized thimerosal (Thi); varying concentrations of buffer: EDTA; media (viable control); and formalin (dead control). After 1 h, solutions were replaced with 150 μL of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazonium bromide). After 4 h, solutions decanted, 100 μL of acid isopropanol added, and the optical density determined at 572 nm to evaluate cell viability. Results Conjunctival and corneal cell toxicity was seen with all preservatives. Depending upon concentration, BAK exhibited from 56% to 89% toxicity. In comparison, Cbl exhibited from 50% to 86%, MP from 30% to 76%, SP from 23% to 59%, and Thi from 70% to 95%. EDTA with minimal toxicity (from 6% to 59%) was indistinguishable from SP. Conclusions Generally, the order of decreasing toxicity at the most commonly used concentrations: Thi (0.0025%) > BAK (0.025%) > Cbl (0.25%) > MP (0.01%) > SP (0.0025%) ≈ EDTA (0.01%). Even at low concentration, these agents will cause some degree of ocular tissue damage. PMID:19284328
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VORICONAZOLE TOXICITY IN MULTIPLE PENGUIN SPECIES.
Hyatt, Michael W; Georoff, Timothy A; Nollens, Hendrik H; Wells, Rebecca L; Clauss, Tonya M; Ialeggio, Donna M; Harms, Craig A; Wack, Allison N
2015-12-01
Aspergillosis is a common respiratory fungal disease in penguins managed under human care. Triazole antifungal drugs, including itraconazole, are most commonly used for treatment; however, itraconazole treatment failures from drug resistance are becoming more common, requiring newer treatment options. Voriconazole, a newer triazole, is being used more often. Until recently, no voriconazole pharmacokinetic studies had been performed in penguins, leading to empiric dosing based on other avian studies. This has led to increased anecdotal reporting of apparent voriconazole toxicity in penguins. This report describes 18 probable and 6 suspected cases of voriconazole toxicity in six penguin species from nine institutions: 12 African penguins (Spheniscus demersus), 5 Humboldt penguins (Spheniscus humboldti), 3 Magellanic penguins (Spheniscus magellanicus), 2 gentoo penguins (Pygoscelis papua papua), 1 macaroni penguin (Eudyptes chrysolophus), and 1 emperor penguin (Aptenodytes forsteri). Observed clinical signs of toxicity included anorexia, lethargy, weakness, ataxia, paresis, apparent vision changes, seizure-like activity, and generalized seizures. Similar signs of toxicity have also been reported in humans, in whom voriconazole therapeutic plasma concentration for Aspergillus spp. infections is 2-6 μg/ml. Plasma voriconazole concentrations were measured in 18 samples from penguins showing clinical signs suggestive of voriconazole toxicity. The concentrations ranged from 8.12 to 64.17 μg/ml, with penguins having plasma concentrations above 30 μg/ml exhibiting moderate to severe neurologic signs, including ataxia, paresis, and seizures. These concentrations were well above those known to result in central nervous system toxicity, including encephalopathy, in humans. This case series highlights the importance of species-specific dosing of voriconazole in penguins and plasma therapeutic drug monitoring. Further investigation, including pharmacokinetic studies, is warranted. The authors recommend caution in determining voriconazole dosages for use in penguin species.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Theunissen, P.T., E-mail: Peter.Theunissen@rivm.nl; Department of Toxicogenomics, Maastricht University, Maastricht; Robinson, J.F.
Alternative assays for developmental toxicity testing are needed to reduce animal use in regulatory toxicology. The in vitro murine neural embryonic stem cell test (ESTn) was designed as an alternative for neurodevelopmental toxicity testing. The integration of toxicogenomic-based approaches may further increase predictivity as well as provide insight into underlying mechanisms of developmental toxicity. In the present study, we investigated concentration-dependent effects of six mechanistically diverse compounds, acetaldehyde (ACE), carbamazepine (CBZ), flusilazole (FLU), monoethylhexyl phthalate (MEHP), penicillin G (PENG) and phenytoin (PHE), on the transcriptome and neural differentiation in the ESTn. All compounds with the exception of PENG altered ESTnmore » morphology (cytotoxicity and neural differentiation) in a concentration-dependent manner. Compound induced gene expression changes and corresponding enriched gene ontology biological processes (GO–BP) were identified after 24 h exposure at equipotent differentiation-inhibiting concentrations of the compounds. Both compound-specific and common gene expression changes were observed between subsets of tested compounds, in terms of significance, magnitude of regulation and functionality. For example, ACE, CBZ and FLU induced robust changes in number of significantly altered genes (≥ 687 genes) as well as a variety of GO–BP, as compared to MEHP, PHE and PENG (≤ 55 genes with no significant changes in GO–BP observed). Genes associated with developmentally related processes (embryonic morphogenesis, neuron differentiation, and Wnt signaling) showed diverse regulation after exposure to ACE, CBZ and FLU. In addition, gene expression and GO–BP enrichment showed concentration dependence, allowing discrimination of non-toxic versus toxic concentrations on the basis of transcriptomics. This information may be used to define adaptive versus toxic responses at the transcriptome level.« less
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An evaluation of microbial growth and corrosion of 316L SS in glycol/seawater mixtures
NASA Technical Reports Server (NTRS)
Lee, Jason S.; Ray, Richard I.; Lowe, Kristine L.; Jones-Meehan, Joanne; Little, Brenda J.
2003-01-01
Glycol/seawater mixtures containing > 50% glycol inhibit corrosion of 316L stainless steel and do not support bacterial growth. The results indicate bacteria are able to use low concentrations of glycol (10%) as a growth medium, but bacterial growth decreased with increasing glycol concentration. Pitting potential, determined by anodic polarization, was used to evaluate susceptibility of 316L SS to corrosion in seawater-contaminated glycol. Mixture containing a minimum concentration of 50% propylene glycol-based coolant inhibited pitting corrosion. A slightly higher minimum concentration (55%) was needed for corrosion protection in ethylene glycol mixtures.
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Critical predicted no effect concentrations (PNECs) should not be based on a single toxicity test.
Chapman, Peter M; Elphick, James R
2015-05-01
Predicted no-effect concentrations (PNECs), which represent the concentration of a substance below which an unacceptable effect most likely will not occur, are widely used for risk assessment and in environmental policy and regulation. They are typically based on single-species laboratory toxicity tests; often, a single test result for the most sensitive endpoints drives the derivation of a PNEC. In the present study, the authors provide a case study emphasizing the importance of determining the reliability of those most sensitive endpoints. Five 21-d Daphnia magna toxicity tests conducted using the same procedures by 2 laboratories gave 20% inhibitory concentration responses to a specific ionic composition of total dissolved solids that varied from 684 mg/L to more than 1510 mg/L. The concentration-response curve was shallow; thus, these differences could have been attributable to chance alone. The authors strongly recommend that the most sensitive endpoints that determine PNECs not be based on a single toxicity test result but rather on the geometric mean of at least 3 test results to adequately assess and bound test variability, especially when the concentration-response curve is shallow. © 2015 SETAC.
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40 CFR 721.1450 - 1,3-Benzenediamine, 4-(1,1-di-methylethyl)-ar-methyl.
Code of Federal Regulations, 2012 CFR
2012-07-01
... washings, equipment washouts, and stormwater runoffs, wastewater treatment in permitted industrial... a Material Safety Data Sheet (“MSDS”) which includes, at a minimum, the language specified in... scientifically valid toxicity test data required under that order, developed according to EPA's Good Laboratory...
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40 CFR 721.1450 - 1,3-Benzenediamine, 4-(1,1-di-methylethyl)-ar-methyl.
Code of Federal Regulations, 2011 CFR
2011-07-01
... washings, equipment washouts, and stormwater runoffs, wastewater treatment in permitted industrial... a Material Safety Data Sheet (“MSDS”) which includes, at a minimum, the language specified in... scientifically valid toxicity test data required under that order, developed according to EPA's Good Laboratory...
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40 CFR 721.1450 - 1,3-Benzenediamine, 4-(1,1-di-methylethyl)-ar-methyl.
Code of Federal Regulations, 2013 CFR
2013-07-01
... washings, equipment washouts, and stormwater runoffs, wastewater treatment in permitted industrial... a Material Safety Data Sheet (“MSDS”) which includes, at a minimum, the language specified in... scientifically valid toxicity test data required under that order, developed according to EPA's Good Laboratory...
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40 CFR 721.1450 - 1,3-Benzenediamine, 4-(1,1-di-methylethyl)-ar-methyl.
Code of Federal Regulations, 2014 CFR
2014-07-01
... washings, equipment washouts, and stormwater runoffs, wastewater treatment in permitted industrial... a Material Safety Data Sheet (“MSDS”) which includes, at a minimum, the language specified in... scientifically valid toxicity test data required under that order, developed according to EPA's Good Laboratory...
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JPRS Report, Proliferation Issues
1992-09-09
agency, Hammam weapons from other sites were brought there under U.N. ’Abd-al-Khaliq ’Abd-al-Ghafur. He did not go into details. supervision for eventual...to have using traditional technologies, it will take between five and a minimum of $20,000. seven years to render harmless the toxic waste already
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40 CFR 799.9430 - TSCA combined chronic toxicity/carcinogenicity.
Code of Federal Regulations, 2010 CFR
2010-07-01
... effects and determine dose-response relationships. The design and conduct should allow for the detection... dynamic inhalation equipment designed to sustain a minimum air flow of 10 air changes per hour, an... measurements during the exposures should be sufficient. If pretest measurements are not within 10% of each...
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40 CFR 799.9430 - TSCA combined chronic toxicity/carcinogenicity.
Code of Federal Regulations, 2011 CFR
2011-07-01
... effects and determine dose-response relationships. The design and conduct should allow for the detection... dynamic inhalation equipment designed to sustain a minimum air flow of 10 air changes per hour, an... measurements during the exposures should be sufficient. If pretest measurements are not within 10% of each...
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40 CFR 799.9430 - TSCA combined chronic toxicity/carcinogenicity.
Code of Federal Regulations, 2013 CFR
2013-07-01
... effects and determine dose-response relationships. The design and conduct should allow for the detection... dynamic inhalation equipment designed to sustain a minimum air flow of 10 air changes per hour, an... measurements during the exposures should be sufficient. If pretest measurements are not within 10% of each...
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40 CFR 799.9430 - TSCA combined chronic toxicity/carcinogenicity.
Code of Federal Regulations, 2012 CFR
2012-07-01
... effects and determine dose-response relationships. The design and conduct should allow for the detection... dynamic inhalation equipment designed to sustain a minimum air flow of 10 air changes per hour, an... measurements during the exposures should be sufficient. If pretest measurements are not within 10% of each...
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40 CFR 799.9430 - TSCA combined chronic toxicity/carcinogenicity.
Code of Federal Regulations, 2014 CFR
2014-07-01
... effects and determine dose-response relationships. The design and conduct should allow for the detection... dynamic inhalation equipment designed to sustain a minimum air flow of 10 air changes per hour, an... measurements during the exposures should be sufficient. If pretest measurements are not within 10% of each...
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Leite, Aracelli de Sousa; Oliveira, George Laylson da Silva; Gomes Júnior, Antonio L.; de Lima, Sidney Gonçalo; Citó, Antônia Maria das Graças Lopes; de Freitas, Rivelilson M.; Melo-Cavalcante, Ana Amélia de C.; Dantas Lopes, José Arimateia
2015-01-01
The cashew nut releases a substance that is known as cashew nut shell liquid (CNSL). There are both natural (iCNSL) and technical (tCNSL) cashew nut shell liquids. This study used an Artemia salina bioassay to evaluate the toxic effects of iCNSL and tCNSL cashew nut shell liquids. It also evaluated the toxicity, cytotoxicity, and mutagenicity of CNSL and its effects on the damage induced by copper sulfate (CuSO4·5H2O) on the meristems' root of Allium cepa. Effects of the damage induced by CuSO4·5H2O were evaluated before (pre-), during (co-), and after (post-) treatments. The iCNSL contained 94.5% anacardic acid, and the tCNSL contained 91.3% cardanol. The liquids were toxic to A. salina. Toxicity, cytotoxicity, and mutagenicity were observed with iCNSL compared with the negative control. Similarly, iCNSL failed to inhibit the toxicity and cytotoxicity of CuSO4·5H2O. The tCNSL was not toxic, cytotoxic, or mutagenic in any of the concentrations. However, the lowest iCNSL concentrations and all of the tCNSL concentrations had preventive, antimutagenic, and reparative effects on micronuclei and on chromosomal aberrations in the A. cepa. Therefore, protective, modulating, and reparative effects may be observed in the A. cepa, depending on the concentration and type of CNSL used. PMID:25861638
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Leite, Aracelli de Sousa; Dantas, Alisson Ferreira; Oliveira, George Laylson da Silva; Gomes Júnior, Antonio L; de Lima, Sidney Gonçalo; Citó, Antônia Maria das Graças Lopes; de Freitas, Rivelilson M; Melo-Cavalcante, Ana Amélia de C; Dantas Lopes, José Arimateia
2015-01-01
The cashew nut releases a substance that is known as cashew nut shell liquid (CNSL). There are both natural (iCNSL) and technical (tCNSL) cashew nut shell liquids. This study used an Artemia salina bioassay to evaluate the toxic effects of iCNSL and tCNSL cashew nut shell liquids. It also evaluated the toxicity, cytotoxicity, and mutagenicity of CNSL and its effects on the damage induced by copper sulfate (CuSO4·5H2O) on the meristems' root of Allium cepa. Effects of the damage induced by CuSO4·5H2O were evaluated before (pre-), during (co-), and after (post-) treatments. The iCNSL contained 94.5% anacardic acid, and the tCNSL contained 91.3% cardanol. The liquids were toxic to A. salina. Toxicity, cytotoxicity, and mutagenicity were observed with iCNSL compared with the negative control. Similarly, iCNSL failed to inhibit the toxicity and cytotoxicity of CuSO4·5H2O. The tCNSL was not toxic, cytotoxic, or mutagenic in any of the concentrations. However, the lowest iCNSL concentrations and all of the tCNSL concentrations had preventive, antimutagenic, and reparative effects on micronuclei and on chromosomal aberrations in the A. cepa. Therefore, protective, modulating, and reparative effects may be observed in the A. cepa, depending on the concentration and type of CNSL used.
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Leslie, Heather A; Hermens, Joop L M; Kraak, Michiel H S
2004-08-01
Body residues of compounds with a narcotic mode of action that exceed critical levels result in baseline toxicity in organisms. Previous studies have shown that internal concentrations in organisms also can be estimated by way of passive sampling. In this experiment, solid-phase microextraction (SPME) fibers were used as a tool to estimate the body residues, which were then compared to measured levels. Past application of SPME fibers in the assessment of toxicity risk of samples has focused on separate exposure of fibers and organisms, often necessitated by the amount of agitation needed in order to achieve steady state in the fibers within a convenient time period. Uptake kinetic studies have shown that in SPME fibers with thin coatings, equilibrium concentrations can be reached without agitation within the time frame of a toxicity test. In contrast to toxicity experiments to date, the SPME fibers in the current study were exposed concomitantly to the test water with the organisms, ensuring an exposure under the exact same conditions. Fibers and two aquatic invertebrate species were exposed to a mixture of four chlorobenzenes with a narcotic mode of action. The total body residue of these compounds in the organisms was determined, as was the acute toxicity resulting from the accumulation. The total body residues of both species were correlated to the total concentrations in SPME fibers. It was concluded that toxicity could be predicted based on total body residue (TBR) estimates from fiber concentrations.
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Elatrous, Souheil; Ouanes-Besbes, Lamia; Ben Sik-Ali, Habiba; Hamouda, Zineb; BenAbdallah, Saoussen; Tilouche, Nejla; Jalloul, Faten; Fkih-Hassen, Mohamed; Dachraoui, Fahmi; Ouanes, Islem; Abroug, Fekri
2015-09-15
To evaluate the dose-effects of Androctonus australis hector (Aah) venom injected subcutaneously on hemodynamics and neurohormonal secretions, 10 anesthetized and ventilated mongrel dogs, were split in two groups (n = 5/group). Subcutaneous injection was done with either 0.2 mg/kg or 0.125 mg/kg of the purified G50 scorpion toxic fraction. Hemodynamic parameters using right heart catheter were recorded and plasma concentrations of catecholamine, troponin, and serum toxic fraction were measured sequentially from baseline to 120 min. We identified the dose of toxic fraction evoking characteristic hemodynamic perturbation of severe envenomation, the time-lapse to envenomation, and the associated plasma level. The injection of 0.125 mg/kg toxic fraction was not associated with significant variations in hemodynamic parameters, whereas the 0.2 mg/kg dose caused envenomation characterized by significant increase in plasma catecholamines, increased pulmonary artery occluded pressure, mean arterial pressure, and systemic vascular resistance (p < 0.05), in association with sustained decline in cardiac output (p < 0.001). Envenomation occurred by the 30th minute, and the corresponding concentration of toxic fraction was 1.14 ng/ml. The current experiment allowed the identification of the sub-lethal dose (0.2 mg/kg) of the toxic fraction of Aah administered by the subcutaneous route. Two parameters with potential clinical relevance were also uncovered: the time-lapse to envenomation and the corresponding concentration of toxic fraction. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Lagnika, Latifou; Amoussa, Abdou Madjid O; Adjileye, Rafatou A A; Laleye, Anatole; Sanni, Ambaliou
2016-01-27
Acmella uliginosa (Asteraceae) is a flowering plant whose leaves are consumed as a vegetable in Benin. They are also traditionally used as an antibiotic in the treatment of infectious diseases. To evaluate the therapeutic potential and toxicity effect of this leafy-vegetable, the antibacterial, antifungal, antioxidant activities and, toxicity and phytochemical constituents were investigated. Dichloromethane, methanol and aqueous extracts of Acmella uliginosa were evaluated for their antimicrobial activity against six bacterial and six fungi strains. Antibacterial and antifungal activities were investigated by microdilution method and agar diffusion method respectively. Antioxidant activity was assessed using the 2,2-diphenyl-1-picryl-hydrazyl assay and phytochemical screening was carried out using standard procedures. Finally, oral acute toxicity at a dose of 2000 mg/kg was done according to the Organization for Economic Co-operation and Development guideline n° 423. The antibacterial activity was broad spectrum, inhibiting both Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration ranged from 0.625 to 5 mg/ml. The antifungal evaluation show that all the extracts inhibited mycelial growth and sporulation of fungi with percentages of inhibition ranging from 9.39 to 75.67% and 22.04 to 99.77%, respectively. In DPPH radical scavenging assay, the effect on reducing free radicals increased in a dose dependent manner. The percentage of inhibition of DPPH ranged from 0.94 to 73.07%. Phytochemical screening revealed the presence of coumarin, flavonoid, naphtoquinone, anthracene derivative, saponin, lignan, triterpene and tannin. The dichloromethane and methanol extracts showed the best biological activities; they were also shown as the best extraction solvents of phytochemicals. In the acute toxicity evaluation, all animals were physically active and no deaths of rats were observed during the test. However, the aqueous extract promoted biochemical, hematological and histopathological alterations of treated rats at 2000 mg/kg body weight. A. uliginosa extracts contains antimicrobial, antioxidant agents and was not lethal for rats when ingested. However, according to the results obtained for biochemical, hematological, and histopathological analysis, caution is required regarding its consumption.
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Brooks, Steven J; Bolam, Thi; Tolhurst, Laura; Bassett, Janice; La Roche, Jay; Waldock, Mike; Barry, Jon; Thomas, Kevin V
2008-05-01
This study investigates the effects of waterborne copper exposure on germling growth in chemically defined seawater. Germlings of the macroalgae, Fucus vesiculosus were exposed to a range of copper and dissolved organic carbon (DOC as humic acid) concentrations over 14 days. Germling growth was found to be a sensitive indicator of copper exposure with total copper (TCu) and labile copper (LCu) EC(50) values of approximately 40 and 20 microg/L, respectively, in the absence of added DOC. The addition of DOC into the exposure media provided germlings with protection against copper toxicity, with an increased TCu EC(50) value of 117.3 microg/L at a corrected DOC (cDOC from humic acid only) concentration of 2.03 mg/L. The LCu EC(50) was not affected by a cDOC concentration of 1.65 mg/L or less, suggesting that the LCu concentration not the TCu concentration was responsible for inhibiting germling growth. However, at a cDOC concentration of approximately 2mg/L an increase in the LCu EC(50) suggests that the LCu concentration may play a role in the overall toxicity to the germlings. This is contrary to current understanding of aquatic copper toxicity and possible explanations for this are discussed.
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Impact of non-constant concentration exposure on lethality of inhaled hydrogen cyanide.
Sweeney, Lisa M; Sommerville, Douglas R; Channel, Stephen R
2014-03-01
The ten Berge model, also known as the toxic load model, is an empirical approach in hazard assessment modeling for estimating the relationship between the inhalation toxicity of a chemical and the exposure duration. The toxic load (TL) is normally expressed as a function of vapor concentration (C) and duration (t), with TL equaling C(n) × t being a typical form. Hypothetically, any combination of concentration and time that yields the same "toxic load" will give a constant biological response. These formulas have been developed and tested using controlled, constant concentration animal studies, but the validity of applying these assumptions to time-varying concentration profiles has not been tested. Experiments were designed to test the validity of the model under conditions of non-constant acute exposure. Male Sprague-Dawley rats inhaled constant or pulsed concentrations of hydrogen cyanide (HCN) generated in a nose-only exposure system for 5, 15, or 30 min. The observed lethality of HCN for the 11 different C versus t profiles was used to evaluate the ability of the model to adequately describe the lethality of HCN under the conditions of non-constant inhalation exposure. The model was found to be applicable under the tested conditions, with the exception of the median lethality of very brief, high concentration, discontinuous exposures.
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Chao, Yin-Kai; Lee, Cheng-Hung; Liu, Kuo-Sheng; Wang, Yi-Chuan; Wang, Chih-Wei; Liu, Shih-Jung
2015-01-01
Inadequate intrapleural drug concentrations caused by poor penetration of systemic antibiotics into the pleural cavity is a major cause of treatment failure in empyema. Herein, we describe a novel antibiotic-eluting pigtail catheter coated with electrospun nanofibers used for the sustained release of bactericidal concentrations of penicillin in the pleural space. Electrospun nanofibers prepared using polylactide-polyglycolide copolymer and penicillin G sodium dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol were used to coat the surface of an Fr6 pigtail catheter. The in vitro patterns of drug release were tested by placing the catheter in phosphate-buffered saline. In vivo studies were performed using rabbits treated with penicillin either intrapleurally (Group 1, 20 mg delivered through the catheter) or systemically (Group 2, intramuscular injection, 10 mg/kg). Penicillin concentrations in the serum and pleural fluid were then measured and compared. In vitro studies revealed a burst release of penicillin (10% of the total dose) occurring in the first 24 hours, followed by a sustained release in the subsequent 30 days. Intrapleural drug levels were significantly higher in Group 1 than in Group 2 (P<0.001). In the former, penicillin concentrations remained above the minimum inhibitory concentration breakpoint throughout the entire study period. In contrast, serum penicillin levels were significantly higher in Group 2 than in Group 1 (P<0.001). Notably, all Group 2 rabbits showed signs of systemic toxicity (paralytic ileus and weight loss). We conclude that our antibiotic-eluting catheter may serve as a novel therapeutic option to treat empyema.
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NASA Astrophysics Data System (ADS)
Orr, Philip T.; Willis, Anusuya; Burford, Michele A.
2018-04-01
Cyanobacteria are oxygenic photosynthetic Gram-negative bacteria that can form potentially toxic blooms in eutrophic and slow flowing aquatic ecosystems. Bloom toxicity varies spatially and temporally, but understanding the mechanisms that drive these changes remains largely a mystery. Changes in bloom toxicity may result from changes in intracellular toxin pool sizes of cyanotoxins with differing molecular toxicities, and/or from changes in the cell concentrations of toxic and non-toxic cyanobacterial species or strains within bloom populations. We show here how first-order rate kinetics at the cellular level can be used to explain how environmental conditions drive changes in bloom toxicity at the ecological level. First order rate constants can be calculated for changes in cell concentration (μ c: specific cell division rate) or the volumetric biomass concentration (μ g: specific growth rate) between short time intervals throughout the cell cycle. Similar first order rate constants can be calculated for changes in nett volumetric cyanotoxin concentration (μ tox: specific cyanotoxin production rate) over similar time intervals. How μ c (or μ g ) covaries with μ tox over the cell cycle shows conclusively when cyanotoxins are being produced and metabolised, and how the toxicity of cells change in response to environment stressors. When μ tox/μ c>1, cyanotoxin cell quotas increase and individual cells become more toxic because the nett cyanotoxin production rate is higher than the cell division rate. When μ tox/μ c=1, cell cyanotoxin quotas remains fixed because the nett cyanotoxin production rate matches the cell division rate. When μ tox/μ c<1, the cyanotoxin cell quota decreases because either the nett cyanotoxin production rate is lower than the cell division rate, or metabolic breakdown and/or secretion of cyanotoxins is occurring. These fundamental equations describe cyanotoxin metabolism dynamics at the cellular level and provide the necessary physiological background to understand how environmental stressors drive changes in bloom toxicity.
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Cavallaro, Michael C; Morrissey, Christy A; Headley, John V; Peru, Kerry M; Liber, Karsten
2017-02-01
Nontarget aquatic insects are susceptible to chronic neonicotinoid insecticide exposure during the early stages of development from repeated runoff events and prolonged persistence of these chemicals. Investigations on the chronic toxicity of neonicotinoids to aquatic invertebrates have been limited to a few species and under different laboratory conditions that often preclude direct comparisons of the relative toxicity of different compounds. In the present study, full life-cycle toxicity tests using Chironomus dilutus were performed to compare the toxicity of 3 commonly used neonicotinoids: imidacloprid, clothianidin, and thiamethoxam. Test conditions followed a static-renewal exposure protocol in which lethal and sublethal endpoints were assessed on days 14 and 40. Reduced emergence success, advanced emergence timing, and male-biased sex ratios were sensitive responses to low-level neonicotinoid exposure. The 14-d median lethal concentrations for imidacloprid, clothianidin, and thiamethoxam were 1.52 μg/L, 2.41 μg/L, and 23.60 μg/L, respectively. The 40-d median effect concentrations (emergence) for imidacloprid, clothianidin, and thiamethoxam were 0.39 μg/L, 0.28 μg/L, and 4.13 μg/L, respectively. Toxic equivalence relative to imidacloprid was estimated through a 3-point response average of equivalencies calculated at 20%, 50%, and 90% lethal and effect concentrations. Relative to imidacloprid (toxic equivalency factor [TEF] = 1.0), chronic (lethality) 14-d TEFs for clothianidin and thiamethoxam were 1.05 and 0.14, respectively, and chronic (emergence inhibition) 40-d TEFs were 1.62 and 0.11, respectively. These population-relevant endpoints and TEFs suggest that imidacloprid and clothianidin exert comparable chronic toxicity to C. dilutus, whereas thiamethoxam induced comparable effects only at concentrations an order of magnitude higher. However, the authors caution that under field conditions, thiamethoxam readily degrades to clothianidin, thereby likely enhancing toxicity. Environ Toxicol Chem 2017;36:372-382. © 2016 SETAC. © 2016 SETAC.
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Zimmermann, Sonja; Wolff, Carolina; Sures, Bernd
2017-05-01
Mainly due to automobile traffic, but also due to other sources, the platinum group elements (PGE) platinum (Pt), palladium (Pd) and rhodium (Rh) are introduced into aquatic biotopes where they accumulate in sediments of lakes and rivers. However, the toxicity of these noble metals to aquatic organisms is not well understood and especially toxicity studies under standardized condition are lacking. Thus, the toxicity of Pt, Pd and Rh to Daphnia magna was tested in single metal exposure experiments according to OECD guideline 202. Immobility and lethality was recorded after 24 h and 48 h of exposure and EC 50 and LC 50 , respectively, were determined. As the nominal exposure concentration of Pd differed significantly from the quantified concentration, the control of the real exposure concentration by chemical analysis is mandatory, especially for Pd. The toxicity decreased in the order Pd > Pt ≫ Rh with e.g. LC 50 (48 h) values of 14 μg/L for Pd, 157 μg/L for Pt and 56,800 μg/L for Rh. The exposure period had a clear effect on the toxicity of Pt, Pd and Rh. For Pt and Rh the endpoint immobility was more sensitive than the endpoint lethality whereas Pd toxicity was similar for both endpoints. The Hill slopes, which are a measure for the steepness of the concentration-response curves, showed no significant discrepancies between the different metals. The binary metal exposure to Pt and Pd revealed a more-than-additive, i.e. a synergistic toxicity using the toxic unit approach. The present study is a start to understand the toxicity of interacting PGE. The modes of action behind the synergistic effect are unclear. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Kelly, Charlene N.; Peltz, Christopher D.; Stanton, Mark R.; Rutherford, David W.; Rostad, Colleen E.
2014-01-01
Waste rock piles from historic mining activities remain unvegetated as a result of metal toxicity and high acidity. Biochar has been proposed as a low-cost remediation strategy to increase soil pH and reduce leaching of toxic elements, and improve plant establishment. In this laboratory column study, biochar made from beetle-killed pine wood was assessed for utility as a soil amendment by mixing soil material from two mine sites collected near Silverton, Colorado, USA with four application rates of biochar (0%, 10%, 20%, 30% vol:vol). Columns were leached seven times over 65 days and leachate pH and concentration of toxic elements and base cations were measured at each leaching. Nutrient availability and soil physical and biological parameters were determined following the incubation period. We investigated the hypotheses that biochar incorporation into acidic mine materials will (1) reduce toxic element concentrations in leaching solution, (2) improve soil parameters (i.e. increase nutrient and water holding capacity and pH, and decrease compaction), and (3) increase microbial populations and activity. Biochar directly increased soil pH (from 3.33 to 3.63 and from 4.07 to 4.77 in the two materials) and organic matter content, and decreased bulk density and extractable salt content in both mine materials, and increased nitrate availability in one material. No changes in microbial population or activity were detected in either mine material upon biochar application. In leachate solution, biochar increased base cations from both materials and reduced the concentrations of Al, Cd, Cu, Pb, and Zn in leachate solution from one material. However, in the material with greater toxic element content, biochar did not reduce concentrations of any measured dissolved toxic elements in leachate and resulted in a potentially detrimental release of Cd and Zn into solution at concentrations above that of the pure mine material. The length of time of effectiveness and specific sorption by biochar is variable by element and the toxic element concentration and acidity of the initial mine material.
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Yang, Ying-Fei; Chen, Pei-Jen; Liao, Vivian Hsiu-Chuan
2016-05-01
Nanoscale zerovalent iron (nZVI) is widely used with large scale for environmental remediation for in situ or ex situ applications. The potential impact of nZVI on biota at environmentally relevant concentrations needs to be elucidated. In this study, the reproductive toxicities of three irons species: carboxymethyl cellulose (CMC)-stabilized nZVI, nanoscale iron oxide (nFe3O4), and ferrous ion (Fe(II)aq) in the soil-dwelling nematode Caenorhabditis elegans were examined. In addition, the generational transfer of reproductive toxicity of CMC-nZVI on C. elegans was investigated. The results showed that CMC-nZVI, nFe3O4, and Fe(II)aq did not cause significant mortality after 24 h exposure at the examined concentrations. Reproductive toxicity assays revealed that CMC-nZVI, nFe3O4, and Fe(II)aq significantly decreased offsprings in parental generation (F0) in accompany with the increased intracellular reactive oxygen species (ROS). Furthermore, the reproductive toxicity of CMC-nZVI at environmentally relevant concentrations was transferrable from the F0 to the F1 and F2 generations, but then recovered in the F3 and F4 generations. Further evidence showed that total irons were accumulated in the F0 and F1 generations of C. elegans after CMC-nZVI parental exposure. This study demonstrated that environmentally relevant concentrations of CMC-nZVI induced multigenerational reproductive toxicity which can be ascribed to its high production of ROS in F0 generation, toxicity of Fe(II)aq, and iron accumulation in C. elegans. Since nZVI is widely used for environmental remediation, considering the multigenerational toxicity, this study thus implicates a potential environmental risk of nZVI-induced nanotoxicity in the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.
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The Role of Nitrogen Fixation in Cyanobacterial Bloom Toxicity in a Temperate, Eutrophic Lake
Beversdorf, Lucas J.; Miller, Todd R.; McMahon, Katherine D.
2013-01-01
Toxic cyanobacterial blooms threaten freshwaters worldwide but have proven difficult to predict because the mechanisms of bloom formation and toxin production are unknown, especially on weekly time scales. Water quality management continues to focus on aggregated metrics, such as chlorophyll and total nutrients, which may not be sufficient to explain complex community changes and functions such as toxin production. For example, nitrogen (N) speciation and cycling play an important role, on daily time scales, in shaping cyanobacterial communities because declining N has been shown to select for N fixers. In addition, subsequent N pulses from N2 fixation may stimulate and sustain toxic cyanobacterial growth. Herein, we describe how rapid early summer declines in N followed by bursts of N fixation have shaped cyanobacterial communities in a eutrophic lake (Lake Mendota, Wisconsin, USA), possibly driving toxic Microcystis blooms throughout the growing season. On weekly time scales in 2010 and 2011, we monitored the cyanobacterial community in a eutrophic lake using the phycocyanin intergenic spacer (PC-IGS) region to determine population dynamics. In parallel, we measured microcystin concentrations, N2 fixation rates, and potential environmental drivers that contribute to structuring the community. In both years, cyanobacterial community change was strongly correlated with dissolved inorganic nitrogen (DIN) concentrations, and Aphanizomenon and Microcystis alternated dominance throughout the pre-toxic, toxic, and post-toxic phases of the lake. Microcystin concentrations increased a few days after the first significant N2 fixation rates were observed. Then, following large early summer N2 fixation events, Microcystis increased and became most abundant. Maximum microcystin concentrations coincided with Microcystis dominance. In both years, DIN concentrations dropped again in late summer, and N2 fixation rates and Aphanizomenon abundance increased before the lake mixed in the fall. Estimated N inputs from N2 fixation were large enough to supplement, or even support, the toxic Microcystis blooms. PMID:23405255
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Ruiz-Pérez, Nancy J; González-Ávila, Marisela; Sánchez-Navarrete, Jaime; Toscano-Garibay, Julia D; Moreno-Eutimio, Mario A; Sandoval-Hernández, Teresa; Arriaga-Alba, Myriam
2016-05-03
The aim of this study was to evaluate the antifungal activity of essential oils (EOs) of Citrus sinensis (C. sinensis) and Citrus latifolia (C. latifolia) against five Candida species: Candida albicans, Candida tropicalis, Candida glabrata, Candida lusitaniae and Candida guilliermondii; and perform its genotoxic evaluation. The EOs of C. sinensis and C. latifolia were obtained from the peel by hydro-distillation. The major components determined by GC-MS were in C. sinensis, d-limonene (96%) and α-myrcene (2.79%); and in C. latifolia, d-limonene (51.64%), β-thujene (14.85%), β-pinene (12.79%) and γ-terpinene (12.8%). Antifungal properties were studied by agar diffusion method, where C. sinensis presented low activity and C. latifolia essential oil was effective to inhibit growing of C. lusitaniae and C. guilliermondii with IC50 of 6.90 and 2.92 μg respectively. The minimum inhibitory concentrations (MIC) for C. sinensis were in a range of 0.42-3.71 μg and for C. latifolia of 0.22-1.30 μg. Genotoxic evaluation was done by Ames test where none of the oils induced point mutations. Flow cytometry was used to measure toxicity in human oral epithelial cells, C. sinensis was not cytotoxic and C. latifolia was toxic at 21.8 μg. These properties might bestow different odontological applications to each essential oil.
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Chaves, Thiago P; Fernandes, Felipe Hugo A; Santana, Cleildo P; Santos, Jocimar S; Medeiros, Francinalva D; Felismino, Délcio C; Santos, Vanda L; Catão, Raïssa Mayer R; Coutinho, Henrique Douglas M; Medeiros, Ana Cláudia D
2016-01-01
Poincianella pyramidalis (Tul.) LP Queiroz (Fabaceae) is an endemic tree of northeastern Brazil, occurring mainly in the Caatinga. Its medicinal use is widespread and is an important therapeutic option against diarrhea, dysentery, and respiratory and urinary infections, among other diseases. In this study we determined the chemical marker and evaluated the interaction between P. pyramidalis extract and a commercial antimicrobial through the use of biological and analytical models. To obtain the extract, an ethanol-water mixture (50:50 v/v) was used as solvent. It was nebulized in a spray dryer using colloidal silicon dioxide as a drying adjuvant. The extract (ENPp) was subjected to HPLC analysis to verify the presence of certain secondary metabolites. The Minimum Inhibitory Concentration (MIC) of the extract against Gram-negative bacteria was determined by broth microdilution and the MIC of synthetic antimicrobial drugs in the presence and absence of the extract. The antioxidant activity of ENPp was evaluated by the DPPH method. The compatibility between the antimicrobial and the extract was evaluated by thermal analysis (TG/DTA). The acute toxicity of the extract was evaluated in vivo in rodents. The results indicate significant additive action of the extract on synthetic antibiotics, considerable antioxidant activity and absence of toxicity. This extract shows high potential for the development of formulations for antimicrobial therapy when used with a vegetable-active ingredient.
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Santana, Cleildo P.; Medeiros, Francinalva D.; Felismino, Délcio C.; Santos, Vanda L.; Catão, Raïssa Mayer R.; Coutinho, Henrique Douglas M.
2016-01-01
Poincianella pyramidalis (Tul.) LP Queiroz (Fabaceae) is an endemic tree of northeastern Brazil, occurring mainly in the Caatinga. Its medicinal use is widespread and is an important therapeutic option against diarrhea, dysentery, and respiratory and urinary infections, among other diseases. In this study we determined the chemical marker and evaluated the interaction between P. pyramidalis extract and a commercial antimicrobial through the use of biological and analytical models. To obtain the extract, an ethanol-water mixture (50:50 v/v) was used as solvent. It was nebulized in a spray dryer using colloidal silicon dioxide as a drying adjuvant. The extract (ENPp) was subjected to HPLC analysis to verify the presence of certain secondary metabolites. The Minimum Inhibitory Concentration (MIC) of the extract against Gram-negative bacteria was determined by broth microdilution and the MIC of synthetic antimicrobial drugs in the presence and absence of the extract. The antioxidant activity of ENPp was evaluated by the DPPH method. The compatibility between the antimicrobial and the extract was evaluated by thermal analysis (TG/DTA). The acute toxicity of the extract was evaluated in vivo in rodents. The results indicate significant additive action of the extract on synthetic antibiotics, considerable antioxidant activity and absence of toxicity. This extract shows high potential for the development of formulations for antimicrobial therapy when used with a vegetable-active ingredient. PMID:27192209
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Mebane, C.A.; Hennessy, D.P.; Dillon, F.S.
2008-01-01
In order to estimate acute-to-chronic toxicity ratios (ACRs) relevant to a coldwater stream community, we exposed rainbow trout (Oncorhynchus mykiss) to cadmium (Cd), lead (Pb), and zinc (Zn) in 96-h acute and 60+ day early-life stage (ELS) exposures. We also tested the acute and sublethal responses of a mayfly (Baetis tricaudatus) and a midge (Chironomus dilutus, formerly C. tentans) with Pb. We examine the statistical interpretation of test endpoints and the acute-to-chronic ratio concept. Increasing the number of control replicates by 2 to 3x decreased the minimum detectable differences by almost half. Pb ACR estimates mostly increased with increasing acute resistance of the organisms (rainbow trout ACRs
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Antimycotic Activity and Genotoxic Evaluation of Citrus sinensis and Citrus latifolia Essential Oils
Ruiz-Pérez, Nancy J.; González-Ávila, Marisela; Sánchez-Navarrete, Jaime; Toscano-Garibay, Julia D.; Moreno-Eutimio, Mario A.; Sandoval-Hernández, Teresa; Arriaga-Alba, Myriam
2016-01-01
The aim of this study was to evaluate the antifungal activity of essential oils (EOs) of Citrus sinensis (C. sinensis) and Citrus latifolia (C. latifolia) against five Candida species: Candida albicans, Candida tropicalis, Candida glabrata, Candida lusitaniae and Candida guilliermondii; and perform its genotoxic evaluation. The EOs of C. sinensis and C. latifolia were obtained from the peel by hydro-distillation. The major components determined by GC-MS were in C. sinensis, d-limonene (96%) and α-myrcene (2.79%); and in C. latifolia, d-limonene (51.64%), β-thujene (14.85%), β-pinene (12.79%) and γ-terpinene (12.8%). Antifungal properties were studied by agar diffusion method, where C. sinensis presented low activity and C. latifolia essential oil was effective to inhibit growing of C. lusitaniae and C. guilliermondii with IC50 of 6.90 and 2.92 μg respectively. The minimum inhibitory concentrations (MIC) for C. sinensis were in a range of 0.42–3.71 μg and for C. latifolia of 0.22–1.30 μg. Genotoxic evaluation was done by Ames test where none of the oils induced point mutations. Flow cytometry was used to measure toxicity in human oral epithelial cells, C. sinensis was not cytotoxic and C. latifolia was toxic at 21.8 μg. These properties might bestow different odontological applications to each essential oil. PMID:27137128
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Balhara, Meenakshi; Ruhil, Sonam; Kumar, Manish; Dhankhar, Sandeep; Chhillar, A K
2014-03-01
An antifungal protein designated as anti-Aspergillus protein (AAP), produced by Escherichia coli DH5α, was purified and characterised. It exhibited a molecular weight of 60 kDa on Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis and depicted 99% purity on ultra performance liquid chromatography. The purified protein manifested antimycotic potential against pathogenic isolates of Aspergillus spp., depicting a minimum inhibitory concentration in the range 15.62-31.25 μg ml(-1) and 5.0-10.0 μg per disc, using microbroth dilution, spore germination inhibition and disc diffusion assays respectively. In vitro toxicity tests demonstrated that it showed no toxicity against human erythrocytes at doses up to 1000 μg ml(-1) . Matrix-assisted laser desorption ionisation-Time-of-flight analysis of trypsin-digested peptides of purified protein and subsequent Mascot search revealed that several peptides of AAP have identity with bacterial siderophore biosynthetic protein, i.e. non-ribosomal peptide synthetase enzyme, involved in critical step of fungal siderophore biosynthesis. Siderophore-based inhibition was further corroborated by Chrome azurol S assay. Hence, the antagonistic effect might be the result of impediment in siderophore-mediated iron uptake and transport process which may cause critical consequences on Aspergillus growth and virulence. © 2013 Blackwell Verlag GmbH.
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Yang, Shih-Chun; Tseng, Chih-Hua; Wang, Pei-Wen; Lu, Po-Liang; Weng, Yi-Han; Yen, Feng-Lin; Fang, Jia-You
2017-01-01
Pterostilbene is a methoxylated derivative of resveratrol originated from natural sources. We investigated the antibacterial activity of pterostilbene against drug-resistant Staphylococcus aureus and the feasibility of using it to treat cutaneous bacteria. The antimicrobial effect was evaluated using an in vitro culture model and an in vivo mouse model of cutaneous infection. The minimum inhibitory concentration (MIC) assay demonstrated a superior biocidal activity of pterostilbene compared to resveratrol (8~16-fold) against methicillin-resistant S. aureus (MRSA) and clinically isolated vancomycin-intermediate S. aureus (VISA). Pterostilbene was found to reduce MRSA biofilm thickness from 18 to 10 μm as detected by confocal microscopy. Pterostilbene showed minimal toxicity to THP-1 cells and was readily engulfed by the macrophages, facilitating the eradication of intracellular MRSA. Pterostilbene exhibited increased skin absorption over resveratrol by 6-fold. Topical pterostilbene application improved the abscess formation produced by MRSA by reducing the bacterial burden and ameliorating the skin architecture. The potent anti-MRSA capability of pterostilbene was related to bacterial membrane leakage, chaperone protein downregulation, and ribosomal protein upregulation. This mechanism of action was different from that of resveratrol according to proteomic analysis and molecular docking. Pterostilbene has the potential to serve as a novel class of topically applied agents for treating MRSA infection in the skin while demonstrating less toxicity to mammalian cells. PMID:28659908
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Evseeva, Tatiana I; Geras'kin, Stanislav A; Shuktomova, Ida I
2003-01-01
Water from natural reservoirs located near the radium production industry storage cell were analyzed using the anaphase-telophase chromosome aberration assay that was carried out on Allium schoenoprasum L. meristematic root tip cells. (262)Ra, (228)U, (232)Th, (210)Pb and (210)Po concentrations in all samples were found not to exceed the radioactivity concentration guides. The concentrations of 10 heavy metal ions were measured in water samples, but only Zn and Mn levels exceeded the maximum permissible concentration for the natural reservoirs. All water samples caused a significant increase of the chromosome aberration frequency as compared to control. The chromosome aberration spectrum analysis shows that the genotoxic effect was a result of chemical toxicity mainly. Two samples from the brook springhead were found to be toxic. The regression analysis results show that the mitotic index increased in parallel to Zn ion levels, and decreased with higher (238)U concentrations. The water samples genotoxicity positively correlated with the Zn concentration. The present work demonstrates that in order to achieve pollutant screening, it is not sufficient to determine the pollutants concentration only. Adequate conclusions on the risk due to environment contamination need to be based on the additional simultaneous use of toxicity and genotoxicity tests. When bioassays indicate some genotoxic and toxic effects, the determination of the chemical composition of the samples is then required. A combination of these two methods allows the identification of the elements that require constant biological monitoring. In the study reported here, those elements are Zn and (238)U.
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Cagnotti, Giulia; Odore, Rosangela; Gardini, Giulia; Amedeo, Stefano; Bertone, Iride; Guerriero, Giulia; Lentini, Laura; Dappiano, Elena; D'Angelo, Antonio
2018-06-18
Levetiracetam can be used for seizure control alone or in combination with other antiepileptic medications. A previous study achieved the minimum targeted serum drug concentration after rectal administration of levetiracetam in healthy dogs. The purpose of the present study was to determine the pharmacokinetics of rectal LEV in dogs presented for cluster seizures or status epilepticus and potentially in treatment with other anti-epileptic drugs. Furthermore, preliminary information on response to this treatment as add-on to the standard treatment protocol is reported. Eight client-owned dogs were enrolled. Plasma levetiracetam concentrations (measured at 0, 30, 60, 90, 120, 180, 240, 360, 720, and 1440 min after drug administration) reached the minimum target concentration (5 μg/ml) at 30 min in all but one patient. At T1 (30 min) the mean concentration was 28.2 ± 15.5 μg/ml. Plasma concentrations remained above the targeted minimum concentration in all patients until 240 min and in 7/8 until 360 min. Six out of eight patients experienced no seizures in the 24-h period after hospitalization and were classified as "responders". Minimum plasma levetiracetam concentration can be reached after rectal administration of 40 mg/kg in dogs affected by cluster seizures and status epilepticus and concurrently receiving other antiepileptic drugs. These preliminary results may encourage the evaluation of rectal levetiracetam as an additional treatment option for cluster seizures and status epilepticus in a larger number of dogs.
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Establishment of a bioassay for the toxicity evaluation and quality control of Aconitum herbs.
Qin, Yi; Wang, Jia-bo; Zhao, Yan-ling; Shan, Li-mei; Li, Bao-cai; Fang, Fang; Jin, Cheng; Xiao, Xiao-he
2012-01-15
Currently, no bioassay is available for evaluating the toxicity of Aconitum herbs, which are well known for their lethal cardiotoxicity and neurotoxicity. In this study, we established a bioassay to evaluate the toxicity of Aconitum herbs. Test sample and standard solutions were administered to rats by intravenous infusion to determine their minimum lethal doses (MLD). Toxic potency was calculated by comparing the MLD. The experimental conditions of the method were optimized and standardized to ensure the precision and reliability of the bioassay. The application of the standardized bioassay was then tested by analyzing 18 samples of Aconitum herbs. Additionally, three major toxic alkaloids (aconitine, mesaconitine, and hypaconitine) in Aconitum herbs were analyzed using a liquid chromatographic method, which is the current method of choice for evaluating the toxicity of Aconitum herbs. We found that for all Aconitum herbs, the total toxicity of the extract was greater than the toxicity of the three alkaloids. Therefore, these three alkaloids failed to account for the total toxicity of Aconitum herbs. Compared with individual chemical analysis methods, the chief advantage of the bioassay is that it characterizes the total toxicity of Aconitum herbs. An incorrect toxicity evaluation caused by quantitative analysis of the three alkaloids might be effectively avoided by performing this bioassay. This study revealed that the bioassay is a powerful method for the safety assessment of Aconitum herbs. Copyright © 2011 Elsevier B.V. All rights reserved.
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McAdam, Kevin; Murphy, James; Eldridge, Alison; Meredith, Clive; Proctor, Christopher
2018-06-01
The concept of a risk continuum for tobacco and nicotine products has been proposed, which differentiates products according to their propensity to reduce toxicant exposure and risk. Cigarettes are deemed the most risky and medicinal nicotine the least. We assessed whether a Reduced-Toxicant Prototype (RTP) cigarette could sufficiently reduce exposure to toxicants versus conventional cigarettes to be considered a distinct category in the risk continuum. We present findings from both pre-clinical and clinical studies in order to examine the potential for reduced smoke toxicant emissions to lower health risks associated with cigarette smoking. We conclude that current toxicant reducing technologies are unable to reduce toxicant emissions sufficiently to manifest beneficial disease-relevant changes in smokers. These findings point to a minimum toxicant exposure standard that future potentially reduced risk products would need to meet to be considered for full biological assessment. The RTP met WHO TobReg proposed limits on cigarette toxicant emissions, however the absence of beneficial disease relevant changes in smokers after six months reduced toxicant cigarette use, does not provide evidence that these regulatory proposals will positively impact risks of smoking related diseases. Greater toxicant reductions, such as those that can be achieved in next generation products e.g. tobacco heating products and electronic cigarettes are likely to be necessary to clearly reduce risks compared with conventional cigarettes. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.
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NASA Astrophysics Data System (ADS)
Chatterjee, Arijit Kumar; Sarkar, Raj Kumar; Prasun Chattopadhyay, Asoke; Aich, Pulakesh; Chakraborty, Ruchira; Basu, Tarakdas
2012-03-01
A method for preparation of copper nanoparticles (Cu-NPs) was developed by simple reduction of CuCl2 in the presence of gelatin as a stabilizer and without applying stringent conditions like purging with nitrogen. The NPs were characterized by spectrophotometry, dynamic light scattering, x-ray diffraction, transmission electron microscopy, atomic force microscopy and x-ray photoelectron spectroscopy. The particles were about 50-60 nm in size and highly stable. The antibacterial activity of this Cu-NP on Gram-negative Escherichia coli was demonstrated by the methods of agar plating, flow cytometry and phase contrast microscopy. The minimum inhibitory concentration (3.0 µg ml-1), minimum bactericidal concentration (7.5 µg ml-1) and susceptibility constant (0.92) showed that this Cu-NP is highly effective against E. coli at a much lower concentration than that reported previously. Treatment with Cu-NPs made E. coli cells filamentous. The higher the concentration of Cu-NPs, the greater the population of filamentous cells; average filament size varied from 7 to 20 µm compared to the normal cell size of ˜2.5 µm. Both filamentation and killing of cells by Cu-NPs (7.5 µg ml-1) also occurred in an E. coli strain resistant to multiple antibiotics. Moreover, an antibacterial effect of Cu-NPs was also observed in Gram-positive Bacillus subtilis and Staphylococcus aureus, for which the values of minimum inhibitory concentration and minimum bactericidal concentration were close to that for E. coli.
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Antibacterial activity and toxicity of silver - nanosilver versus ionic silver
NASA Astrophysics Data System (ADS)
Kvitek, L.; Panacek, A.; Prucek, R.; Soukupova, J.; Vanickova, M.; Kolar, M.; Zboril, R.
2011-07-01
The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.
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Raybould, Alan; Burns, Andrea; Hamer, Mick
2014-01-01
Laboratory testing for possible adverse effects of insecticidal proteins on non-target organisms (NTOs) is an important part of many ecological risk assessments for regulatory decision-making about the cultivation of insect-resistant genetically modified (IRGM) crops. To increase confidence in the risk assessments, regulatory guidelines for effects testing specify that representative surrogate species for NTOs are exposed to concentrations of insecticidal proteins that are in excess of worst-case predicted exposures in the field. High concentrations in effects tests are achieved by using protein test substances produced in microbes, such as Escherichia coli. In a study that exposed Daphnia magna to a single high concentration of a microbial test substance containing Vip3Aa20, the insecticidal protein in MIR162 maize, small reductions in growth were observed. These effects were surprising as many other studies strongly suggest that the activity of Vip3Aa20 is limited to Lepidoptera. A plausible explanation for the effect on growth is that high concentrations of test substance have a non-toxic effect on Daphnia, perhaps by reducing its feeding rate. A follow-up study tested that hypothesis by exposing D. magna to several concentrations of Vip3Aa20, and a high concentration of a non-toxic protein, bovine serum albumin (BSA). Vip3Aa20 and BSA had sporadic effects on the reproduction and growth of D. magna. The pattern of the effects suggests that they result from non-toxic effects of high concentrations of protein, and not from toxicity. The implications of these results for regulatory NTO effects testing and ERA of IRGM crops are discussed.
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Mixtures of Chemical Pollutants at European Legislation Safety Concentrations: How Safe Are They?
Carvalho, Raquel N.; Arukwe, Augustine; Ait-Aissa, Selim; Bado-Nilles, Anne; Balzamo, Stefania; Baun, Anders; Belkin, Shimshon; Blaha, Ludek; Brion, François; Conti, Daniela; Creusot, Nicolas; Essig, Yona; Ferrero, Valentina E. V.; Flander-Putrle, Vesna; Fürhacker, Maria; Grillari-Voglauer, Regina; Hogstrand, Christer; Jonáš, Adam; Kharlyngdoh, Joubert B.; Loos, Robert; Lundebye, Anne-Katrine; Modig, Carina; Olsson, Per-Erik; Pillai, Smitha; Polak, Natasa; Potalivo, Monica; Sanchez, Wilfried; Schifferli, Andrea; Schirmer, Kristin; Sforzini, Susanna; Stürzenbaum, Stephen R.; Søfteland, Liv; Turk, Valentina; Viarengo, Aldo; Werner, Inge; Yagur-Kroll, Sharon; Zounková, Radka; Lettieri, Teresa
2014-01-01
The risk posed by complex chemical mixtures in the environment to wildlife and humans is increasingly debated, but has been rarely tested under environmentally relevant scenarios. To address this issue, two mixtures of 14 or 19 substances of concern (pesticides, pharmaceuticals, heavy metals, polyaromatic hydrocarbons, a surfactant, and a plasticizer), each present at its safety limit concentration imposed by the European legislation, were prepared and tested for their toxic effects. The effects of the mixtures were assessed in 35 bioassays, based on 11 organisms representing different trophic levels. A consortium of 16 laboratories was involved in performing the bioassays. The mixtures elicited quantifiable toxic effects on some of the test systems employed, including i) changes in marine microbial composition, ii) microalgae toxicity, iii) immobilization in the crustacean Daphnia magna, iv) fish embryo toxicity, v) impaired frog embryo development, and vi) increased expression on oxidative stress-linked reporter genes. Estrogenic activity close to regulatory safety limit concentrations was uncovered by receptor-binding assays. The results highlight the need of precautionary actions on the assessment of chemical mixtures even in cases where individual toxicants are present at seemingly harmless concentrations. PMID:24958932
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Priority-pollutant trace elements in streambed sediments of the Cook Inlet basin, Alaska, 1998-2000
Frenzel, Steven A.
2002-01-01
Trace element concentrations in 48 streambed sediment samples collected at 47 sites in the Cook Inlet Basin, Alaska, were compared to concentrations from studies in the conterminous United States using identical methods and to Probable Effect Concentrations. Concentrations of arsenic, chromium, mercury, and nickel in the 0.063-mm size fraction of streambed sediments from the Cook Inlet Basin were elevated relative to reference sites in the conterminous United States. Concentrations of cadmium, lead, and zinc were highest at the most urbanized site in Anchorage and at two sites downstream from an ore body in Lake Clark National Park and Preserve. At least 35 percent of the 48 samples collected in the Cook Inlet Basin exceeded the Probable Effect Concentration for arsenic, chromium, or nickel. More than 50 percent of the samples were considered to have low potential toxicity for cadmium, lead, mercury, nickel, selenium, and zinc. A Probable Effect Concentration quotient that reflects the combined toxicity of arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc was exceeded in 44 percent of the samples from the Cook Inlet Basin. The potential toxicity was high in the Denali and Lake Clark National Parks and Preserves where organic carbon concentrations in streambed sediments were low. However, potential toxicity results should be considered in context with the very small amounts of fine-grained sediment present in the streambed sediments of the Cook Inlet Basin.
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Toxicity of acid mine pit lake water remediated with limestone and phosphorus
DOE Office of Scientific and Technical Information (OSTI.GOV)
Neil, L.L.; McCullough, C.D.; Lund, M.A.
2009-11-15
Pit lakes are increasingly common worldwide and have potential to provide many benefits. However, lake water toxicity may require remediation before beneficial end uses can be realised. Three treatments to remediate AMD (pH similar to 4.8) pit lake water containing elevated concentrations of Al and Zn from Collie, Western Australia were tested in mesocosms. Treatments were: (a) limestone neutralisation (L), (b) phosphorus amendment (P), and c) combined limestone neutralisation and phosphorus amendment (L+P). Laboratory bioassays with Ceriodaphnia cf. dubia, Chlorella protothecoides and Tetrahymena thermophila assessed remediation. Limestone neutralisation increased pH and reduced heavy metal concentrations by 98% (Al) to 14%more » (Mg), removing toxicity to the three test species within 2 months. Phosphorus amendment removed toxicity after 6 months of treatment. However, phosphorus amendment to prior limestone neutralisation failed to reduce toxicity more than limestone neutralisation alone. Low concentrations of both phosphorus and nitrogen appear to limit phytoplankton population growth in all treatments.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
van Gestel, C.A.; Ma, W.C.
The acute toxicity of five chlorophenols for two earthworm species was determined in two sandy soils differing in organic matter content and the results were compared with adsorption data. Adsorption increased with increasing organic matter content of the soils, but for tetra- and pentachlorophenol was also influenced by soil pH. Earthworm toxicity was significantly higher in the soil with a low level of organic matter. This difference disappeared when LC50 values were recalculated to concentrations in soil solution using adsorption data. Eisenia fetida andrei showed LC50 values lower than those of Lumbricus rubellus although bioaccumulation was generally higher in themore » latter species. Toxicity and bioaccumulation based on soil solution concentrations increased with increasing lipophilicity of the chlorophenols. The present results indicate that the toxicity and bioaccumulation and therefore the bioavailability of chlorophenols in soil to earthworms are dependent on the concentration in soil solution and can be predicted on the basis of adsorption data. Both the toxicity of and bioaccumulation data on chlorophenols in earthworms demonstrated surprisingly good agreement with those on chlorophenols in fish.« less
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A METHOD OF ASSESSING AIR TOXICS CONCENTRATIONS IN URBAN AREAS USING MOBILE PLATFORM MEASUREMENTS
The objective of this paper is to demonstrate an approach to characterize the spatial variability in ambient air concentrations using mobile platform measurements. This approach may be useful for air toxic assessments in Environmental Justice applications, epidemiological studies...
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A HYBRID MODELING APPROACH TO RESOLVE POLLUTANT CONCENTRATIONS IN AN URBAN AREA
A modeling tool that can resolve contributions from individual sources to the urban environment is critical for air-toxics exposure assessments. Air toxics are often chemically reactive and may have background concentrations originated from distant sources. Grid models are the be...
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LARGE-SCALE PREDICTIONS OF MOBILE SOURCE CONTRIBUTIONS TO CONCENTRATIONS OF TOXIC AIR POLLUTANTS
This presentation shows concentrations and deposition of toxic air pollutants predicted by a 3-D air quality model, the Community Multi Scale Air Quality (CMAQ) modeling system. Contributions from both on-road and non-road mobile sources are analyzed.
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Biological treatment and toxicity of low concentrations of oily wastewater (bilgewater).
Stamper, David M; Montgomery, Michael T
2008-08-01
The biodegradability and toxicity of low concentrations of oily wastewater (bilgewater) were tested under simulated sanitary wastewater treatment conditions. This was done to establish the feasibility of a combined shipboard oily and nonoily wastewater treatment system. The biodegradability of oily wastewater was determined by proxy; 14C-labeled dodecane, toluene, and phenanthrene (representing alkane, aromatic, and polyaromatic compounds, respectively) were mineralized in petroleum fuels and lubricants. We found that low concentrations of oily wastewater components were mineralized, even in the presence of more abundant substrates (such as synthetic graywater, containing vegetable oil, detergent, gelatin, and starch). The toxic effects of diesel fuel and several other components of oily wastewater (such as surfactants and a synthetic lubricant) on a naïve wastewater assemblage was also tested. In concentrations much higher than would be expected under normal shipboard conditions, we found no evidence of toxic effects of the bilgewater compounds tested. Thus, a combined shipboard bilgewater and sanitary wastewater system might be feasible.
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Brooks, Steven J; Bolam, Thi; Tolhurst, Laura; Bassett, Janice; La Roche, Jay; Waldock, Mike; Barry, Jon; Thomas, Kevin V
2007-08-01
The effects of humic acid (HA) on copper speciation and its subsequent toxicity to the sensitive early life stages of the Pacific oyster (Crassostrea gigas) are presented. Differential pulse anodic stripping voltammetry with a hanging mercury drop electrode was used to measure the copper species as labile copper (LCu; free ion and inorganic copper complexes) and total copper (TCu) with respect to increasing HA concentration. The TCu and LCu 50% effect concentrations (EC50s) in the absence of HA were 20.77 microg/L (95% confidence interval [CI], 24.02-19.97 microg/L) and 8.05 microg/L (95% CI, 9.6-5.92 microg/L) respectively. A corrected dissolved organic carbon (DOC) concentration (HA only) of 1.02 mg/L was required to significantly increase the TCu EC50 to approximately 41.09 microg/L (95% CI, 44.27-37.52 microg/L; p < 0.05), almost doubling that recorded when DOC (as HA) was absent from the test media. In contrast, the LCu EC50 was unaffected by changes in DOC concentration and was stable throughout the corrected DOC concentration range. The absence of change in the LCu EC50, despite increased HA concentration, suggests that the LCu fraction, not TCu, was responsible for the observed toxicity to the oyster embryo. This corresponds with the current understanding of copper toxicity and supports the free-ion activity model for copper toxicity.
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Essential oil of Psidium cattleianum leaves: antioxidant and antifungal activity.
Castro, Micheli R; Victoria, Francine N; Oliveira, Daniela H; Jacob, Raquel G; Savegnago, Lucielli; Alves, Diego
2015-02-01
Psidium cattleianum Sabine (Myrtacea) is rich in vitamin C and phenolic compounds, including epicatechin and gallic acid as the main components. To evaluate the antifungal and antioxidant capacity in vitro of the essential oil of araçá (EOA). The acute toxicity of the EOA also was evaluated in mice. The leaves of the P. cattleianum were extracted by steam distillation. The antioxidant capacity was evaluated by in vitro tests [1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), ferric ion reducing antioxidant power (FRAP), linoleic acid oxidation, thiobarbituric acid reactive species (TBARS)], and ex vivo analysis [TBARS, δ-aminulevunilate dehydratase (δ-Ala-D) and catalase activity, non-protein thiols (NPSH), and ascorbic acid levels]. The toxicity was studied in mice by a single oral administration of EOA; and the antifungal activity was performed with five strains of fungi. The EOA exhibited antioxidant activity in the FRAP assay and reduced lipid peroxidation in the cortex (Imax = 32.90 ± 2.62%), hippocampus (IC50 = 48.00 ± 3.00 µg/ml and Imax = 32.90 ± 2.62%), and cerebellum (Imax = 45.40 ± 14.04%) of mice. Acute administration of the EOA by the oral route did not cause toxicological effects in mice (LD50 > 500 µg/ml). The EOA also showed antifungal activity through of the determination minimum inhibitory concentration (MIC) values ranging from 41.67 ± 18.04 to 166.70 ± 72.17 µg/ml for tested strains. The results of present study indicate that EOA possess antioxidant properties, antifungal and not cause toxicity at tested doses.
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Melching-Kollmuss, Stephanie; Dekant, Wolfgang; Kalberlah, Fritz
2010-03-01
Limits for tolerable concentrations of ground water metabolites ("non-relevant metabolites" without targeted toxicities and specific classification and labeling) derived from active ingredients (AI) of plant protection products (PPPs) are discussed in the European Union. Risk assessments for "non-relevant metabolites" need to be performed when concentrations are above 0.75 microg/L. Since oral uptake is the only relevant exposure pathway for "non-relevant metabolites", risk assessment approaches as used for other chemicals with predominantly oral exposure in humans are applicable. The concept of "thresholds of toxicological concern" (TTC) defines tolerable dietary intakes for chemicals without toxicity data and is widely applied to chemicals present in food in low concentrations such as flavorings. Based on a statistical evaluation of the results of many toxicity studies and considerations of chemical structures, the TTC concept derives a maximum daily oral intake without concern of 90 microg/person/day for non-genotoxic chemicals, even for those with appreciable toxicity. When using the typical exposure assessment for drinking water contaminants (consumption of 2L of drinking water/person/day, allocation of 10% of the tolerable daily intake to drinking water), a TTC-based upper concentration limit of 4.5 microg/L for "non-relevant metabolites" in ground/drinking water is delineated. In the present publication it has been evaluated, whether this value would cover all relevant toxicities (repeated dose, reproductive and developmental, and immune effects). Taking into account, that after evaluation of specific reproduction toxicity data from chemicals and pharmaceuticals, a value of 1 microg/kgbw/day has been assessed as to cover developmental and reproduction toxicity, a TTC value of 60 microg/person/day was assessed as to represent a safe value. Based on these reasonable worst case assumptions, a TTC-derived threshold of 3 microg/L in drinking water is derived. When a non-relevant metabolite is present in concentration below 3 microg/L, animal testing for toxicity is not considered necessary for a compound-specific risk assessment since the application of the TTC covers all relevant toxicities to be considered in such assessment and any health risk resulting from these exposures is very low. (c) 2009 Elsevier Inc. All rights reserved.
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Health and Environmental Hazards of Electronic Waste in India.
Borthakur, Anwesha
2016-04-01
Technological waste in the form of electronic waste (e-waste) is a threat to all countries. E-waste impacts health and the environment by entering the food chain in the form of chemical toxicants and exposing the population to deleterious chemicals, mainly in the form of polycyclic aromatic hydrocarbons and persistent organic pollutants. This special report tries to trace the environmental and health implications of e-waste in India. The author concludes that detrimental health and environmental consequences are associated with e-waste and the challenge lies in producing affordable electronics with minimum chemical toxicants.
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Analytical methods for toxic gases from thermal degradation of polymers
NASA Technical Reports Server (NTRS)
Hsu, M.-T. S.
1977-01-01
Toxic gases evolved from the thermal oxidative degradation of synthetic or natural polymers in small laboratory chambers or in large scale fire tests are measured by several different analytical methods. Gas detector tubes are used for fast on-site detection of suspect toxic gases. The infrared spectroscopic method is an excellent qualitative and quantitative analysis for some toxic gases. Permanent gases such as carbon monoxide, carbon dioxide, methane and ethylene, can be quantitatively determined by gas chromatography. Highly toxic and corrosive gases such as nitrogen oxides, hydrogen cyanide, hydrogen fluoride, hydrogen chloride and sulfur dioxide should be passed into a scrubbing solution for subsequent analysis by either specific ion electrodes or spectrophotometric methods. Low-concentration toxic organic vapors can be concentrated in a cold trap and then analyzed by gas chromatography and mass spectrometry. The limitations of different methods are discussed.
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Busquet, François; Strecker, Ruben; Rawlings, Jane M; Belanger, Scott E; Braunbeck, Thomas; Carr, Gregory J; Cenijn, Peter; Fochtman, Przemyslaw; Gourmelon, Anne; Hübler, Nicole; Kleensang, André; Knöbel, Melanie; Kussatz, Carola; Legler, Juliette; Lillicrap, Adam; Martínez-Jerónimo, Fernando; Polleichtner, Christian; Rzodeczko, Helena; Salinas, Edward; Schneider, Katharina E; Scholz, Stefan; van den Brandhof, Evert-Jan; van der Ven, Leo T M; Walter-Rohde, Susanne; Weigt, Stefan; Witters, Hilda; Halder, Marlies
2014-08-01
The OECD validation study of the zebrafish embryo acute toxicity test (ZFET) for acute aquatic toxicity testing evaluated the ZFET reproducibility by testing 20 chemicals at 5 different concentrations in 3 independent runs in at least 3 laboratories. Stock solutions and test concentrations were analytically confirmed for 11 chemicals. Newly fertilised zebrafish eggs (20/concentration and control) were exposed for 96h to chemicals. Four apical endpoints were recorded daily as indicators of acute lethality: coagulation of the embryo, lack of somite formation, non-detachment of the tail bud from the yolk sac and lack of heartbeat. Results (LC50 values for 48/96h exposure) show that the ZFET is a robust method with a good intra- and inter-laboratory reproducibility (CV<30%) for most chemicals and laboratories. The reproducibility was lower (CV>30%) for some very toxic or volatile chemicals, and chemicals tested close to their limit of solubility. The ZFET is now available as OECD Test Guideline 236. Considering the high predictive capacity of the ZFET demonstrated by Belanger et al. (2013) in their retrospective analysis of acute fish toxicity and fish embryo acute toxicity data, the ZFET is ready to be considered for acute fish toxicity for regulatory purposes. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.
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Assessment and prediction of joint algal toxicity of binary mixtures of graphene and ionic liquids.
Wang, Zhuang; Zhang, Fan; Wang, Se; Peijnenburg, Willie J G M
2017-10-01
Graphene and ionic liquids (ILs) released into the environment will interact with each other. So far however, the risks associated with the concurrent exposure of biota to graphene and ILs in the environment have received little attention. The research reported here focused on observing and predicting the joint toxicity effects in the green alga Scenedesmus obliquus exposed to binary mixtures of intrinsic graphene (iG)/graphene oxide (GO) and five ILs of varying anionic and cationic types. The isolated ILs in the binary mixtures were the main contributors to toxicity. The binary GO-IL mixtures resulted in more severe joint toxicity than the binary iG-IL mixtures, irrespective of mixture ratios. The mechanism of the joint toxicity may be associated with the adsorption capability of the graphenes for the ILs, the dispersion stability of the graphenes in aquatic media, and modulation of the binary mixtures-induced oxidative stress. A toxic unit assessment showed that the graphene and IL toxicities were additive at low concentration of the mixtures but antagonistic at high concentration of the mixtures. Predictions made using the concentration addition and independent action models were close to the observed joint toxicities regardless of mixture types and mixture ratios. These findings provide new insights that are of use in the risk assessment of mixtures of engineered nanoparticles and other environmentally relevant contaminants. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Gauthier, Patrick T; Norwood, Warren P; Prepas, Ellie E; Pyle, Greg G
2015-10-06
Mixtures of metals and polycyclic aromatic hydrocarbons (PAHs) occur ubiquitously in aquatic environments, yet relatively little is known regarding their potential to produce non-additive toxicity (i.e., antagonism or potentiation). A review of the lethality of metal-PAH mixtures in aquatic biota revealed that more-than-additive lethality is as common as strictly additive effects. Approaches to ecological risk assessment do not consider non-additive toxicity of metal-PAH mixtures. Forty-eight-hour water-only binary mixture toxicity experiments were conducted to determine the additive toxic nature of mixtures of Cu, Cd, V, or Ni with phenanthrene (PHE) or phenanthrenequinone (PHQ) using the aquatic amphipod Hyalella azteca. In cases where more-than-additive toxicity was observed, we calculated the possible mortality rates at Canada's environmental water quality guideline concentrations. We used a three-dimensional response surface isobole model-based approach to compare the observed co-toxicity in juvenile amphipods to predicted outcomes based on concentration addition or effects addition mixtures models. More-than-additive lethality was observed for all Cu-PHE, Cu-PHQ, and several Cd-PHE, Cd-PHQ, and Ni-PHE mixtures. Our analysis predicts Cu-PHE, Cu-PHQ, Cd-PHE, and Cd-PHQ mixtures at the Canadian Water Quality Guideline concentrations would produce 7.5%, 3.7%, 4.4% and 1.4% mortality, respectively.
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Schmidt, Stine N; Holmstrup, Martin; Smith, Kilian E C; Mayer, Philipp
2013-07-02
A 7-day mixture toxicity experiment with the terrestrial springtail Folsomia candida was conducted, and the effects were linked to three different mixture exposure parameters. Passive dosing from silicone was applied to tightly control exposure levels and compositions of 12 mixture treatments, containing the polycyclic aromatic hydrocarbons (PAHs) naphthalene, phenanthrene, and pyrene. Springtail lethality was then linked to sum chemical activities (∑a), sum equilibrium lipid concentrations (∑C(lipid eq.)), and sum toxic units (∑TU). In each case, the effects of all 12 mixture treatments could be fitted to one sigmoidal exposure-response relationship. The effective lethal chemical activity (La50) of 0.027 was well within the expected range for baseline toxicity of 0.01-0.1. Linking the effects to the lipid-based exposure parameter yielded an effective lethal concentration (LC(lipid eq 50)) of 133 mmol kg(-1) lipid in good correspondence with the lethal membrane burden for baseline toxicity (40-160 mmol kg(-1) lipid). Finally, the effective lethal toxic unit (LTU50) of 1.20 was rather close to the expected value of 1. Altogether, passive dosing provided tightly controlled mixture exposure in terms of both level and composition, while ∑a, ∑C(lipid eq.), and ∑TU allowed baseline toxicity to be linked to mixture exposure.
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An, Jinsung; Jho, Eun Hea; Nam, Kyoungphile
2015-04-09
Current risk characterization in ecological risk assessment does not consider bioavailability of heavy metals, which highly depends on physicochemical properties of environmental media. This study was set to investigate the effect of humic acid (HA), used as a surrogate of organic matter, on Pb toxicity and the subsequent effect on risk characterization in ecological risk assessment. Pb toxicity was assessed using Microtox(®) in the presence and absence of two different forms of HA, particulate HA (pHA) and dissolved HA (dHA). With increasing contact time, the EC10 values increased (i.e., the toxic effects decreased) and the dissolved Pb concentrations of the filtrates decreased. The high correlation (R = 0.88, p < 0.001) between toxic effects determined using both the mixture and its filtrate as exposure media leads us to conclude that the Pb toxicity highly depends on the soluble fraction. Also, reduced Pb toxicity with increasing dHA concentrations, probably due to formation of Pb-dHA complexes, indicated that Pb toxicity largely comes from free Pb ions. Overall, this study shows the effect of HA on metal toxicity alleviation, and emphasizes the need for incorporating the bioavailable heavy metal concentrations in environmental media as a point of exposure in ecological risk assessment. Copyright © 2015 Elsevier B.V. All rights reserved.
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Photosynthetic and cellular toxicity of cadmium in Chlorella vulgaris.
Ou-Yang, Hui-Ling; Kong, Xiang-Zhen; Lavoie, Michel; He, Wei; Qin, Ning; He, Qi-Shuang; Yang, Bin; Wang, Rong; Xu, Fu-Liu
2013-12-01
The toxic effects of cadmium (Cd) on the green alga Chlorella vulgaris were investigated by following the response to Cd of various toxicity endpoints (cell growth, cell size, photochemical efficiency of PSII in the light or Φ(PSII), maximal photochemical efficiency or Fv/Fm, chlorophyll a fluorescence, esterase activity, and cell viability). These toxicity endpoints were studied in laboratory batch cultures of C. vulgaris over a long-term 96-h exposure to different Cd concentrations using flow cytometry and pulse amplitude modulated fluorometry. The sequence of sensitivity of these toxicity endpoints was: cell yield > Φ(PSII) ≈ esterase activity > Fv/Fm > chlorophyll a fluorescence ≈ cell viability. It is shown that cell apoptosis or cell death only accounted for a minor part of the reduction in cell yield even at very high algistatic free Cd²⁺ concentrations, and other mechanisms such as blocked cell divisions are major contributors to cell yield inhibition. Furthermore, cadmium may affect both the electron donors and acceptors of the electron transport chain at high free Cd²⁺ concentration. Finally, the resistance of cells to cell death was size-dependent; medium-sized cells had the highest toxicity threshold. The present study brings new insights into the toxicity mechanisms of Cd in C. vulgaris and provides a detailed comparison of the sensitivity of various Cd toxicity endpoints. © 2013 SETAC.
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Martins, António; Moreira, Cristiana; Vale, Micaela; Freitas, Marisa; Regueiras, Ana; Antunes, Agostinho; Vasconcelos, Vitor
2011-01-01
Blooms of toxic cyanobacteria are becoming increasingly frequent, mainly due to water quality degradation. This work applied qPCR as a tool for early warning of microcystin(MC)-producer cyanobacteria and risk assessment of water supplies. Specific marker genes for cyanobacteria, Microcystis and MC-producing Microcystis, were quantified to determine the genotypic composition of the natural Microcystis population. Correlations between limnological parameters, pH, water temperature, dissolved oxygen and conductivity and MC concentrations as well as Microcystis abundance were assessed. A negative significant correlation was observed between toxic (with mcy genes) to non-toxic (without mcy genes) genotypes ratio and the overall Microcystis density. The highest proportions of toxic Microcystis genotypes were found 4–6 weeks before and 8–10 weeks after the peak of the bloom, with the lowest being observed at its peak. These results suggest positive selection of non-toxic genotypes under favorable environmental growth conditions. Significant positive correlations could be found between quantity of toxic genotypes and MC concentration, suggesting that the method applied can be useful to predict potential MC toxicity risk. No significant correlation was found between the limnological parameters measured and MC concentrations or toxic genotypes proportions indicating that other abiotic and biotic factors should be governing MC production and toxic genotypes dynamics. The qPCR method here applied is useful to rapidly estimate the potential toxicity of environmental samples and so, it may contribute to the more efficient management of water use in eutrophic systems. PMID:22072994
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Calenda, Emile; Baste, Jean Marc; Hajjej, Ridha; Danielou, Eric; Peillon, Christophe
2014-03-01
A case of systemic ropivacaine toxicity from a continuous thoracic paravertebral block in an adult patient who received a lobectomy is presented. The catheter was placed by the surgeon. Eleven hours after the start of the infusion, the patient experienced an arrhythmia leading to death. The total venous plasma concentration of ropivacaine was high (3.2 μg/mL). Furthermore, the patient had severe hypoalbuminemia (albumin 24 g/L), which resulted in the increase of the unbound ropivacaine plasma concentration that was responsible for the toxic side effects. Copyright © 2014 Elsevier Inc. All rights reserved.
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Maloney, Erin M; Morrissey, Christy A; Headley, John V; Peru, Kerry M; Liber, Karsten
2017-11-01
Extensive agricultural use of neonicotinoid insecticide products has resulted in the presence of neonicotinoid mixtures in surface waters worldwide. Although many aquatic insect species are known to be sensitive to neonicotinoids, the impact of neonicotinoid mixtures is poorly understood. In the present study, the cumulative toxicities of binary and ternary mixtures of select neonicotinoids (imidacloprid, clothianidin, and thiamethoxam) were characterized under acute (96-h) exposure scenarios using the larval midge Chironomus dilutus as a representative aquatic insect species. Using the MIXTOX approach, predictive parametric models were fitted and statistically compared with observed toxicity in subsequent mixture tests. Single-compound toxicity tests yielded median lethal concentration (LC50) values of 4.63, 5.93, and 55.34 μg/L for imidacloprid, clothianidin, and thiamethoxam, respectively. Because of the similar modes of action of neonicotinoids, concentration-additive cumulative mixture toxicity was the predicted model. However, we found that imidacloprid-clothianidin mixtures demonstrated response-additive dose-level-dependent synergism, clothianidin-thiamethoxam mixtures demonstrated concentration-additive synergism, and imidacloprid-thiamethoxam mixtures demonstrated response-additive dose-ratio-dependent synergism, with toxicity shifting from antagonism to synergism as the relative concentration of thiamethoxam increased. Imidacloprid-clothianidin-thiamethoxam ternary mixtures demonstrated response-additive synergism. These results indicate that, under acute exposure scenarios, the toxicity of neonicotinoid mixtures to C. dilutus cannot be predicted using the common assumption of additive joint activity. Indeed, the overarching trend of synergistic deviation emphasizes the need for further research into the ecotoxicological effects of neonicotinoid insecticide mixtures in field settings, the development of better toxicity models for neonicotinoid mixture exposures, and the consideration of mixture effects when setting water quality guidelines for this class of pesticides. Environ Toxicol Chem 2017;36:3091-3101. © 2017 SETAC. © 2017 SETAC.
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Assessing toxic effects of [Omim]Cl and [Omim]BF4 in zebrafish adults using a biomarker approach.
Liu, Tong; Guo, Yingying; Wang, Jinhua; Wang, Jun; Zhu, Lusheng; Zhang, Jun; Zhang, Cheng
2016-04-01
In the present study, the toxic effects of 1-octyl-3-methylimidazolium chloride ([Omim]Cl) and 1-octyl-3-methylimidazolium tetrafluoroborate ([Omim]BF4) on the zebrafish livers were studied at 0, 5, 10, 20, and 40 mg L(-1) on the 7th and 14th days. In addition, the concentrations of [Omim]Cl and [Omim]BF4 in the test water, the acute toxicity of the two ionic liquids (ILs), and the influence of anions on the toxicity of the ILs were evaluated. The acute toxicity test results showed 50 % lethal concentration (LC50) values of 152.3 ± 12.1 mg L(-1) for [Omim]Cl and 144.0 ± 11.4 mg L(-1) for [Omim]BF4. At the lowest concentration investigated (5 mg L(-1)), [Omim]Cl and [Omim]BF4 did not significantly affect zebrafish during the exposure period. However, the toxic effects of these substances were enhanced as dosing concentrations and exposure times were increased. Levels of reactive oxygen species (ROS) were significantly enhanced on the 7th day after 20 mg L(-1) and on the 14th day after 10 mg L(-1) of either substance was applied, resulting in oxidative damage, such as lipid peroxidation and DNA damage. The experimental results also indicated little effect of the anions on the toxicity of ILs and consistent toxic effects of [Omim]Cl and [Omim]BF4. Graphical Abstract The graphical abstract for the present study after exposure to [Omim]Cl and [Omim]BF4. The letter R represents the anions Cl(-) and BF4 (.)
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Arias-Andrés, M; Rämö, R; Mena Torres, F; Ugalde, R; Grandas, L; Ruepert, C; Castillo, L E; Van den Brink, P J; Gunnarsson, J S
2016-10-25
Costa Rica is a tropical country with one of the highest biodiversity on Earth. It also has an intensive agriculture, and pesticide runoff from banana and pineapple plantations may cause a high toxicity risk to non-target species in rivers downstream the plantations. We performed a first tier risk assessment of the maximum measured concentrations of 32 pesticides detected over 4 years in the River Madre de Dios (RMD) and its coastal lagoon on the Caribbean coast of Costa Rica. Species sensitivity distributions (SSDs) were plotted in order to derive HC 5 values for each pesticide, i.e., hazard concentrations for 5 % of the species, often used as environmental criteria values in other countries. We also carried out toxicity tests for selected pesticides with native Costa Rican species in order to calculate risk coefficients according to national guidelines in Costa Rica. The concentrations of herbicides diuron and ametryn and insecticides carbofuran, diazinon, and ethoprophos exceeded either the HC 5 value or the lower limit of its 90 % confidence interval suggesting toxic risks above accepted levels. Risk coefficients of diuron and carbofuran derived using local guidelines indicate toxicity risks as well. The assessed fungicides did not present acute toxic risks according to our analysis. Overall, these results show a possible toxicity of detected pesticides to aquatic organisms and provide a comparison of Costa Rican national guidelines with more refined methods for risk assessment based on SSDs. Further higher tier risk assessments of pesticides in this watershed are also necessary in order to consider pesticide water concentrations over time, toxicity from pesticide mixtures, and eventual effects on ecosystem functions.
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Prediction of toxic metals concentration using artificial intelligence techniques
NASA Astrophysics Data System (ADS)
Gholami, R.; Kamkar-Rouhani, A.; Doulati Ardejani, F.; Maleki, Sh.
2011-12-01
Groundwater and soil pollution are noted to be the worst environmental problem related to the mining industry because of the pyrite oxidation, and hence acid mine drainage generation, release and transport of the toxic metals. The aim of this paper is to predict the concentration of Ni and Fe using a robust algorithm named support vector machine (SVM). Comparison of the obtained results of SVM with those of the back-propagation neural network (BPNN) indicates that the SVM can be regarded as a proper algorithm for the prediction of toxic metals concentration due to its relative high correlation coefficient and the associated running time. As a matter of fact, the SVM method has provided a better prediction of the toxic metals Fe and Ni and resulted the running time faster compared with that of the BPNN.
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Galhano, Victor; Peixoto, Francisco; Gomes-Laranjo, José; Fernández-Valiente, Eduardo
2010-04-01
Bentazon and molinate are selective herbicides recommended for integrated weed management in rice. Their toxicity on growth and some biochemical and physiological parameters of Nostoc muscorum, an abundant cyanobacterium in Portuguese rice fields, was evaluated under laboratory conditions during time- and concentration-dependent exposure for 72 h. Results showed that toxic concentrations (0.75-2 mM) of both herbicides have pleiotropic effects on the cyanobacterium. Molinate was more toxic than bentazon to growth, respiration, chlorophyll-a, carotenoids, and phycobiliproteins contents. Protein content was increased by both herbicides although the effect was particularly evident with higher concentrations of molinate (1.5-2 mM). The herbicides had contrasting effects on carbohydrates content: molinate increased this organic fraction whereas bentazon decreased it. Photosynthesis and respiration were inhibited by both herbicides.
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[Interest of toxicological analysis for poisonings].
Mégarbane, Bruno; Baud, Frédéric J
2008-04-30
The clinical approach of the poisoned patients is mainly based on the analysis of the circumstances of intoxication and the search for toxidromes. Toxicological analysis aims to detect the toxicants or measure their concentrations, in order to confirm the hypothesis of poisoning, to evaluate its severity and to help the follow-up regarding the treatment efficiency. Emergent toxicological analysis appears only useful if the method is specific and the results rapidly obtained. Therefore, systematic screening using immunochesmistry-based tests is not recommended in the situation of emergency. Measurement of blood concentrations of the toxicants is only indicated if it may influence the patient management. However, in the perspective of research, the study of toxicokinetic/toxicodynamic relationships, i.e. the relationships between the toxicant effects and its blood concentrations, may be helpful to understand the inter-individual variability of the response to a toxicant.
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Naidoo, V; du Preez, M; Rakgotho, T; Odhav, B; Buckley, C A
2002-01-01
Industrial effluents and leachates from hazardous landfill sites were tested for toxicity using the anaerobic toxicity assay. This test was done on several industrial effluents (brewery spent grain effluent, a chemical industry effluent, size effluent), and several hazardous landfill leachates giving vastly different toxicity results. The brewery effluent, spent grain effluent and size effluent were found to be less toxic than the chemical effluent and hazardous landfill leachate samples. The chemical industry effluent was found to be most toxic. Leachate samples from the H:h classified hazardous landfill site were found to be less toxic at high concentrations (40% (v/v)) while the H:H hazardous landfill leachate samples were found to be more toxic even at low concentrations of 4% (v/v). The 30 d biochemical methane potential tests revealed that the brewery effluent, organic spent grain effluent and size effluent were 89%, 63%, and 68% biodegradable, respectively. The leachate from Holfontein hazardous landfill site was least biodegradable (19%) while the chemical effluent and Aloes leachate were 29% and 32% biodegradable under anaerobic conditions.
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Haldane, S L; Davis, R M
2009-07-01
This case series of five dogs describes the effects of ingesting large amounts of an iron EDTA snail-bait product. In all cases signs of toxicity occurred between 6 and 24 h after ingestion and included abdominal pain and haemorrhagic gastroenteritis. Two of the dogs had pretreatment serum iron levels measured and in both cases the levels were above normal limits. All of the dogs were treated with iron chelation therapy and supportive care including intravenous fluids, analgesics, gastric protectants and antibiotics. Chelation therapy with desferrioxamine mesylate did not cause adverse effects in any of the dogs and all survived to discharge. The effects of iron EDTA snail bait in dogs requires further study and minimum toxic doses need to be established.
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Pesticide toxicity index for freshwater aquatic organisms
Munn, Mark D.; Gilliom, Robert J.
2001-01-01
The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program is designed to assess current water-quality conditions, changes in water quality over time, and the effects of natural and human factors on water quality for the Nation's streams and ground-water resources. For streams, one of the most difficult parts of the assessment is to link chemical conditions to effects on aquatic biota, particularly for pesticides, which tend to occur in streams as complex mixtures with strong seasonal patterns. A Pesticide Toxicity Index (PTI) was developed that combines pesticide exposure of aquatic biota (measured concentrations of pesticides in stream water) with toxicity estimates (standard endpoints from laboratory bioassays) to produce a single index value for a sample or site. The development of the PTI was limited to pesticide compounds routinely measured in NAWQA studies and to toxicity data readily available from existing databases. Qualifying toxicity data were found for one or more types of test organisms for 75 of the 83 pesticide compounds measured in NAWQA samples, but with a wide range of bioassays per compound (1 to 65). There were a total of 2,824 bioassays for the 75 compounds, including 287 48-hour EC50 values (concentration at which 50 percent of test organisms exhibit a nonlethal response) for freshwater cladocerans, 585 96-hour LC50 values (concentration lethal to 50 percent of test organisms) for freshwater benthic invertebrates, and 1,952 96-hour LC50 values for freshwater fish. The PTI for a particular sample is the sum of toxicity quotients (measured concentration divided by the median toxicity concentration from bioassays) for each detected pesticide. The PTI can be calculated for specific groups of pesticides and for specific taxonomic groups.While the PTI does not determine whether water in a sample is toxic, its values can be used to rank or compare the toxicity of samples or sites on a relative basis for use in further analysis or additional assessments. The PTI approach may be useful as a basis for comparing the potential significance of pesticides in different streams on a common basis, for evaluating relations between pesticide exposure and observed biological conditions, and for prioritizing where further studies are most needed.
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Son, Jino; Lee, Yun-Sik; Lee, Sung-Eun; Shin, Key-Il; Cho, Kijong
2017-01-01
Bioavailability and toxicity of Cu, Mn, and Ni in Paronychiurus kimi were investigated after 28 days of exposure to OECD artificial soil spiked with these metals. Uptake and effect of Cu, Mn, and Ni on the reproduction of P. kimi were related to different metal fractions (water-soluble, 0.01 M CaCl 2 -extractable or porewater metal concentrations). Cu and Mn concentrations in P. kimi increased with increasing Cu and Mn concentrations in the soil, while Ni contents in P. kimi reached a plateau at a concentration higher than 200 mg/kg in soil. Both uptake and juvenile production related well to different metal fractions, suggesting that these metal fractions are suitable for assessing bioavailability and toxicity of metals in P. kimi. When toxicity for reproduction was compared, as reflected by EC 50 values, the order of metal toxicity varied depending upon how exposure concentration was expressed. Moreover, the results of proteomic analysis showed that several proteins involved in the immune system, neuronal outgrowth, and metal ion binding were up-regulated in P. kimi following short-term (7 days) exposure to sublethal level (corresponding to 50% of the EC 50 ) of Cu, Mn, or Ni, respectively. This suggests that the ecotoxicoproteomic approach seems to be a promising tool for early exposure warnings below which significant adverse effects are unlikely to occur. This study demonstrated that a combination of chemical and biological measures can provide information about metal bioavailability and toxicity to which P. kimi has been exposed.
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A high throughput passive dosing format for the Fish Embryo Acute Toxicity test.
Vergauwen, Lucia; Schmidt, Stine N; Stinckens, Evelyn; Maho, Walid; Blust, Ronny; Mayer, Philipp; Covaci, Adrian; Knapen, Dries
2015-11-01
High throughput testing according to the Fish Embryo Acute Toxicity (FET) test (OECD Testing Guideline 236) is usually conducted in well plates. In the case of hydrophobic test substances, sorptive and evaporative losses often result in declining and poorly controlled exposure conditions. Therefore, our objective was to improve exposure conditions in FET tests by evaluating a passive dosing format using silicone O-rings in standard 24-well polystyrene plates. We exposed zebrafish embryos to a series of phenanthrene concentrations until 120h post fertilization (hpf), and obtained a linear dilution series. We report effect values for both mortality and sublethal morphological effects based on (1) measured exposure concentrations, (2) (lipid normalized) body residues and (3) chemical activity. The LC50 for 120hpf was 310μg/L, CBR50 (critical body residue) was 2.72mmol/kg fresh wt and La50 (lethal chemical activity) was 0.047. All values were within ranges expected for baseline toxicity. Impaired swim bladder inflation was the most pronounced morphological effect and swimming activity was reduced in all exposure concentrations. Further analysis showed that the effect on swimming activity was not attributed to impaired swim bladder inflation, but rather to baseline toxicity. We conclude that silicone O-rings (1) produce a linear dilution series of phenanthrene in the 120hpf FET test, (2) generate and maintain aqueous concentrations for reliable determination of effect concentrations, and allow for obtaining mechanistic toxicity information, and (3) cause no toxicity, demonstrating its potential as an extension of the FET test when testing hydrophobic chemicals. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Hartzell, Sharon E; Unger, Michael A; Vadas, George G; Yonkos, Lance T
2018-03-01
Although the complexity of contaminant mixtures in sediments can confound the identification of causative agents of adverse biological response, understanding the contaminant(s) of primary concern at impacted sites is critical to sound environmental management and remediation. In the present study, a stock mixture of 18 polycyclic aromatic hydrocarbon (PAH) compounds was prepared to reflect the variety and relative proportions of PAHs measured in surface sediment samples collected from discrete areas of a historically contaminated industrial estuary. This site-specific PAH stock mixture was spiked into nontoxic in-system and out-of-system field-collected reference sediments in dilution series spanning the range of previously measured total PAH concentrations from the region. Spiked sediments were evaluated in 10-d Leptocheirus plumulosus tests to determine whether toxicity in laboratory-created PAH concentrations was similar to the toxicity found in field-collected samples with equivalent PAH concentrations. The results show that toxicity of contaminated sediments was not explained by PAH exposure, while indicating that toxicity in spiked in-system (fine grain, high total organic carbon [TOC]) and out-of-system (course grain, low TOC) sediments was better explained by porewater PAH concentrations, measured using an antibody-based biosensor that quantified 3- to 5-ring PAHs, than total sediment PAH concentrations. The study demonstrates the application of site-specific spiking experiments to evaluate sediment toxicity at sites with complex mixtures of multiple contaminant classes and the utility of the PAH biosensor for rapid sediment-independent porewater PAH analysis. Environ Toxicol Chem 2018;37:893-902. © 2017 SETAC. © 2017 SETAC.
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Carr, R.S.; Chapman, D.C.; Presley, B.J.; Biedenbach, J.M.; Robertson, L.; Boothe, P.; Kilada, R.; Wade, T.; Montagna, P.
1996-01-01
As part of a multidisciplinary program to assess the potential long-term impacts of offshore oil and gas exploration and production activities in the Gulf of Mexico, sediment chemical analyses and porewater toxicity tests were conducted in the vicinity of five offshore platforms. Based on data from sea urchin fertilization and embryological development assays, toxicity was observed near four of the five platforms sampled; the majority of the toxic samples were collected within 150 m of a platform. There was excellent agreement among the results of porewater tests with three different species (sea urchin embryological development, polychaete reproduction, and copepod nauplii survival). The sediment concentrations of several metals were well in excess of sediment quality assessment guidelines at a number of stations, and good agreement was observed between predicted and observed toxicity. Porewater metal concentrations compared with EC50, LOEC, and NOEC values generated for water-only exposures indicated that the porewater concentrations for several metals were high enough to account for the observed toxicity. Results of these studies utilizing highly sensitive toxicity tests suggest that the contaminant-induced impacts from offshore platforms are limited to a localized area in the immediate vicinity of the platforms.
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Acute toxicity tests and meta-analysis identify gaps in tropical ecotoxicology for amphibians.
Ghose, Sonia L; Donnelly, Maureen A; Kerby, Jacob; Whitfield, Steven M
2014-09-01
Amphibian populations are declining worldwide, particularly in tropical regions where amphibian diversity is highest. Pollutants, including agricultural pesticides, have been identified as a potential contributor to decline, yet toxicological studies of tropical amphibians are very rare. The present study assesses toxic effects on amphibians of 10 commonly used commercial pesticides in tropical agriculture using 2 approaches. First, the authors conducted 8-d toxicity assays with formulations of each pesticide using individually reared red-eyed tree frog (Agalychnis callidryas) tadpoles. Second, they conducted a review of available data for the lethal concentration to kill 50% of test animals from the US Environmental Protection Agency's ECOTOX database to allow comparison with their findings. Lethal concentration estimates from the assays ranged over several orders of magnitude. The nematicides terbufos and ethoprophos and the fungicide chlorothalonil were very highly toxic, with evident effects within an order of magnitude of environmental concentrations. Acute toxicity assays and meta-analysis show that nematicides and fungicides are generally more toxic than herbicides yet receive far less research attention than less toxic herbicides. Given that the tropics have a high diversity of amphibians, the findings emphasize the need for research into the effects of commonly used pesticides in tropical countries and should help guide future ecotoxicological research in tropical regions. © 2014 SETAC.
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Gupta, Anshu; Paulraj, R
2017-07-01
Landfills are considered the most widely practiced method for disposal of municipal solid waste (MSW) and 95% of the total MSW collected worldwide is disposed of in landfills. Leachate produced from MSW landfills may contain a number of pollutants and pose a potential environmental risk for surface as well as ground water. In the present study, chemical analysis and toxicity assessment of landfill leachate have been carried out. Leachate samples were collected from Ghazipur landfill site, New Delhi. Leachates were characterized by measuring the concentration of heavy metals (Pb, Cu, Cr and Ni), 5-day biochemical oxygen demand (BOD 5 ), chemical oxygen demand (COD), pH, electrical conductivity and SO 4 2 -. For toxicity testing of leachate, Triticum aestivum (wheat) was selected and testing was done in a time- and dose-dependent manner using the crude leachate. Median lethal concentration after 24 and 48 h of exposure was observed. The main objective of this study was to evaluate toxicity of MSW landfill leachate and establish a possible correlation between the measured physicochemical parameters and resultant toxicity. Statistical analysis showed that toxicity was dependent on the concentration of heavy metals (Pb, Cu), conductivity, and organic matter (COD and BOD5).
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Haq, Mehreen; Gonzalez, Nelson; Mintz, Keenan; Jaja-Chimedza, Asha; De Jesus, Christopher Lawrence; Lydon, Christina; Welch, Aaron Z.; Berry, John P.
2016-01-01
Ochratoxins, and particularly ochratoxin A (OTA), are toxic fungal-derived contaminants of food and other agricultural products. Growing evidence supports the degradation of OTA by chemical, enzymatic and/or microbial means as a potential approach to remove this mycotoxin from food products. In particular, hydrolysis of OTA to ochratoxin α (OTα) and phenylalanine is the presumptive product of degradation in most cases. In the current study, we employed the zebrafish (Danio rerio) embryo, as a model of vertebrate development to evaluate, the teratogenicity of OTA and OTα. These studies show that OTA is potently active in the zebrafish embryo toxicity assay (ZETA), and that toxicity is both concentration- and time-dependent with discernible and quantifiable developmental toxicity observed at nanomolar concentrations. On the other hand, OTα had no significant effect on embryo development at all concentrations tested supporting a decreased toxicity of this degradation product. Taken together, these results suggest that ZETA is a useful, and highly sensitive, tool for evaluating OTA toxicity, as well as its degradation products, toward development of effective detoxification strategies. Specifically, the results obtained with ZETA, in the present study, further demonstrate the toxicity of OTA, and support its degradation via hydrolysis to OTα as an effective means of detoxification. PMID:26861395
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Haq, Mehreen; Gonzalez, Nelson; Mintz, Keenan; Jaja-Chimedza, Asha; De Jesus, Christopher Lawrence; Lydon, Christina; Welch, Aaron; Berry, John P
2016-02-05
Ochratoxins, and particularly ochratoxin A (OTA), are toxic fungal-derived contaminants of food and other agricultural products. Growing evidence supports the degradation of OTA by chemical, enzymatic and/or microbial means as a potential approach to remove this mycotoxin from food products. In particular, hydrolysis of OTA to ochratoxin α (OTα) and phenylalanine is the presumptive product of degradation in most cases. In the current study, we employed the zebrafish (Danio rerio) embryo, as a model of vertebrate development to evaluate, the teratogenicity of OTA and OTα. These studies show that OTA is potently active in the zebrafish embryo toxicity assay (ZETA), and that toxicity is both concentration- and time-dependent with discernible and quantifiable developmental toxicity observed at nanomolar concentrations. On the other hand, OTα had no significant effect on embryo development at all concentrations tested supporting a decreased toxicity of this degradation product. Taken together, these results suggest that ZETA is a useful, and highly sensitive, tool for evaluating OTA toxicity, as well as its degradation products, toward development of effective detoxification strategies. Specifically, the results obtained with ZETA, in the present study, further demonstrate the toxicity of OTA, and support its degradation via hydrolysis to OTα as an effective means of detoxification.
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Farré, Marinella; Asperger, Daniela; Kantiani, Lina; González, Susana; Petrovic, Mira; Barceló, Damià
2008-04-01
In this work, the contributions of triclosan and its metabolite methyl triclosan to the overall acute toxicity of wastewater were studied using Vibrio fischeri. The protocol used in this paper involved various steps. First, the aquatic toxicities of triclosan and methyl triclosan were determined for standard substances, and the 50% effective concentrations (EC(50)) were determined for these compounds. Second, the toxic responses to different mixtures of triclosan, methyl triclosan, and surfactants were studied in different water matrices, i.e., Milli-Q water, groundwater and wastewater, in order to evaluate (i) the antagonistic or synergistic effects, and (ii) the influence of the water matrices. Finally, chemical analysis was used in conjunction with the toxicity results in order to assess the aquatic toxicities of triclosan and its derivative in wastewaters. In this study, the toxicities of 45 real samples corresponding to the influents and effluents from eight wastewater treatment works (WWTW) were analyzed. Thirty-one samples were from a wastewater treatment plant (WWTP) equipped with two pilot-scale membrane bioreactors (MBR), and the influent and the effluent samples after various treatments were characterized via different chromatographic approaches, including solid-phase extraction (SPE), liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), and SPE coupled to gas chromatography-mass spectrometry (GC-MS). The toxicity was determined by measuring the bioluminescence inhibition of Vibrio fischeri. In order to complete the study and to extrapolate the results to different WWTPs, the toxicity to V. fischeri of samples from seven more plants was analyzed, as were their triclosan and methyl triclosan concentrations. Good agreement was established between the overall toxicity values and concentrations of the biocides, indicating that triclosan is one of the major toxic organic pollutants currently found in domestic wastewaters.
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The influence of particles on bioavailability and toxicity of pesticides in surface water.
Knauer, Katja; Homazava, Nadzeya; Junghans, Marion; Werner, Inge
2017-07-01
Environmental risk assessment is an essential part of the approval process for pesticides. Exposure concentrations are compared with ecotoxicological data obtained from standardized laboratory studies and, if available, from field studies to determine the risk of a substance or formulation for aquatic communities. Predicted concentrations in surface waters are derived using, for example, the European FOrum for the Co-ordination of pesticide fate models and their USe (FOCUS) or the German Exposit models, which distinguish between exposure to dissolved and particle-associated pesticide concentrations, because the dissolved concentration is thought to be the best predictor of bioavailability and toxicity. Water and particle-associated concentrations are estimated based on the organic carbon-water partitioning coefficient (K OC ). This review summarizes published information on the influence of natural suspended solids on bioavailability and toxicity of pesticides to aquatic organisms (algae, invertebrates and fish), and the value of log K OC and log K OW (octanol-water coefficient) as sole predictors of the bioavailable fraction is discussed. The information showed that: 1) the quality and origin of suspended solids played an important role in influencing pesticide bioavailability and toxicity; 2) a decrease in toxicity due to the presence of suspended solids was shown only for pyrethroid insecticides with log K OW greater than 5, but the extent of this reduction depended on particle concentration and size, and potentially also on the ecotoxicological endpoint; 3) for pesticides with a log K OW less than 3 (e.g., triazines, carbamates, and organophosphates), the impact of particles on bioavailability and toxicity is small and species dependent; and 4) pesticide bioavailability is greatly influenced by the test species and their physiology (e.g., feeding behavior or digestion). We conclude that exposure of aquatic organisms to pesticides and environmental risk of many pesticides might be underestimated in prospective risk assessment, when predicted environmental concentration is estimated based on the K OC of a compound. Integr Environ Assess Manag 2017;13:585-600. © 2016 SETAC. © 2016 SETAC.
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Toxicity of tributyltin (TBT) to terrestrial organisms and its species sensitivity distribution.
Silva, Patrícia V; Silva, Ana Rita R; Mendo, Sónia; Loureiro, Susana
2014-01-01
The contamination of the terrestrial environment by disposal of tributyltin (TBT) by contaminated harbour sediments, sewage sludge and/or biocide products has been raising concerns and it may pose a risk to soil invertebrates and plants. This study aimed to improve the amount and quality of data for TBT toxicity in soils in order to assess the ecological risk of TBT to the terrestrial ecosystems. For this, bioassays were performed with the species Porcellionides pruinosus, Folsomia candida, Brassica rapa and Triticum aestivum to evaluate the toxic effects of TBT (as chloride) on these species. Additionally, this study contributed to increase the amount of data concerning TBT toxicity on soil dwelling organisms. The results showed a dose-response relationship between TBT concentration and the increase of toxicity in all species tested. These results were collated with results from literature to construct species sensitivity distributions (SSDs) and to calculate the hazardous concentration at 5% (HC₅) for all data, for each type of soil and TBT formulation used. The HC₅ value for TBT in soil was 2.06 mg TBT/kg soil dw. Little information is available concerning the concentrations of TBT in soils. In addition the predicted no-effect concentration (PNEC) value was determined to be 30 μg/kg soil. Only one study was found referring to TBT contaminated soils, and where TBT concentrations were lower than 0.024 μg TBT/kg for the wetland soil. Therefore it can be concluded that the real TBT concentrations determined represent low risk for environmental effects. In conclusion, the construction of SSDs and the calculation of HC5 using all the data available showed to be a more suitable method rather than the construction of several SSDs for each soil and TBT types. Further investigations concerning TBT concentrations and toxicity on soil organisms need to be performed to increase data and improve risk calculations. © 2013.
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Fairchild, J.F.; Allert, A.L.; Feltz, K.P.; Nelson, K.J.; Valle, J.A.
2009-01-01
Clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) is a pyridine herbicide frequently used to control invasive, noxious weeds in the northwestern United States. Clopyralid exhibits low acute toxicity to fish, including the rainbow trout (Oncorhynchus mykiss) and the threatened bull trout (Salvelinus confluentus). However, there are no published chronic toxicity data for clopyralid and fish that can be used in ecological risk assessments. We conducted 30-day chronic toxicity studies with juvenile rainbow trout exposed to the acid form of clopyralid. The 30-day maximum acceptable toxicant concentration (MATC) for growth, calculated as the geometric mean of the no observable effect concentration (68 mg/L) and the lowest observable effect concentration (136 mg/L), was 96 mg/L. No mortality was measured at the highest chronic concentration tested (273 mg/L). The acute:chronic ratio, calculated by dividing the previously published 96-h acutely lethal concentration (96-h ALC50; 700 mg/L) by the MATC was 7.3. Toxicity values were compared to a four-tiered exposure assessment profile assuming an application rate of 1.12 kg/ha. The Tier 1 exposure estimation, based on direct overspray of a 2-m deep pond, was 0.055 mg/L. The Tier 2 maximum exposure estimate, based on the Generic Exposure Estimate Concentration model (GEENEC), was 0.057 mg/L. The Tier 3 maximum exposure estimate, based on previously published results of the Groundwater Loading Effects of Agricultural Management Systems model (GLEAMS), was 0.073 mg/L. The Tier 4 exposure estimate, based on published edge-of-field monitoring data, was estimated at 0.008 mg/L. Comparison of toxicity data to estimated environmental concentrations of clopyralid indicates that the safety factor for rainbow trout exposed to clopyralid at labeled use rates exceeds 1000. Therefore, the herbicide presents little to no risk to rainbow trout or other salmonids such as the threatened bull trout. ?? 2009 US Government.
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Plants’ Natural Products as Alternative Promising Anti-Candida Drugs
Soliman, Sameh; Alnajdy, Dina; El-Keblawy, Ali A.; Mosa, Kareem A.; Khoder, Ghalia; Noreddin, Ayman M.
2017-01-01
Candida is a serious life-threatening pathogen, particularly with immunocompromised patients. Candida infections are considered as a major cause of morbidity and mortality in a broad range of immunocompromised patients. Candida infections are common in hospitalized patients and elderly people. The difficulty to eradicate Candida infections is owing to its unique switch between yeast and hyphae forms and more likely to biofilm formations that render resistance to antifungal therapy. Plants are known sources of natural medicines. Several plants show significant anti-Candida activities and some of them have lower minimum inhibitory concentration, making them promising candidates for anti-Candida therapy. However, none of these plant products is marketed for anti-Candida therapy because of lack of sufficient information about their efficacy, toxicity, and kinetics. This review revises major plants that have been tested for anti-Candida activities with recommendations for further use of some of these plants for more investigation and in vivo testing including the use of nanostructure lipid system. PMID:28989245
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Polyketides from two Chaetomium species and their biological functions.
Li, He; Liao, Zhong-Bin; Tang, Dan; Han, Wen-Bo; Zhang, Qiang; Gao, Jin-Ming
2018-04-16
Four new secondary metabolites, chaetosemins G-J (1-4), along with 11 known ones (5-15) were isolated from the culture of C. seminudum C208 and Chaetomium sp. C521. Their structures were determined by extensive NMR spectroscopic analyses. These metabolites were evaluated in vitro for antifungal, antioxidant, toxicity, and α-glucosidase inhibitory activities. Chaetosemin J (4) and monaschromone (5) significantly inhibited the growth of four plant pathogenic fungi Botrytis cinerea, Alternaria solani, Magnaporthe oryzae, and Gibberella saubinettii with the minimum inhibitory concentrations (MIC) values ranging from 6.25 to 25.0 μM. Moreover, both epicoccone B (11) and flavipin (14) exhibited the DPPH free radical scavenging ability with IC 50 values of 10.8 and 7.2 μM, respectively, and had more potent α-glucosidase inhibition than the drug acarbose with IC 50 values of 27.3 and 33.8 μM, respectively. Monaschromone (5) might act as the lead compound of pesticide.
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Abdi, Mahnaz M; Abdullah, Luqman Chuah; Sadrolhosseini, Amir R; Mat Yunus, Wan Mahmood; Moksin, Mohd Maarof; Tahir, Paridah Md
2011-01-01
A new sensing area for a sensor based on surface plasmon resonance (SPR) was fabricated to detect trace amounts of mercury and lead ions. The gold surface used for SPR measurements were modified with polypyrrole-chitosan (PPy-CHI) conducting polymer composite. The polymer layer was deposited on the gold surface by electrodeposition. This optical sensor was used for monitoring toxic metal ions with and without sensitivity enhancement by chitosan in water samples. The higher amounts of resonance angle unit (ΔRU) were obtained for PPy-CHI film due to a specific binding of chitosan with Pb(2+) and Hg(2+) ions. The Pb(2+) ion bind to the polymer films most strongly, and the sensor was more sensitive to Pb(2+) compared to Hg(2+). The concentrations of ions in the parts per million range produced the changes in the SPR angle minimum in the region of 0.03 to 0.07. Data analysis was done by Matlab software using Fresnel formula for multilayer system.
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Krátký, Martin; Vinsova, Jarmila
2016-01-01
The global tuberculosis epidemic and emergence of drug resistance call for intensive research on new antimycobacterial agents. Recent development is focused mainly on heterocyclic molecules. In many cases, introduction of sulphur has improved antimicrobial activity; many drugs feature a sulphur heterocycle. Thiophene derivatives and thiadiazoles including derived ortho-condensed heterocycles have been found to have a wide range of biological activities. This review highlights the recent progress in the field with a focus on whole-cell antimycobacterial activity of the agents as well as targeting of enzymes from Mycobacterium tuberculosis. Some of the compounds have exhibited high activity with submicromolar minimum inhibitory concentrations including activity against drug-resistant strains and/or IC50 values for a range of enzymes as their targets (InhA, dehydroquinase, Pks13, carbonic anhydrases, DprE1). Mechanisms of action, toxicity, and structure-activity relationships are also discussed. Several compounds have exhibited promising in vitro and in vivo activities and safety profiles, thus constituting novel, promising leads.
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Sivakumar, K. K.; Rajasekharan, A.; Rao, R.; Narasimhan, B.
2013-01-01
In the present investigation, a series of 12 Mannich bases (QP1-12) and 5 Schiff bases (QSP1-5) of pyrazol-5(4H)-one moiety containing 3-(hydrazinyl)-2-phenylquinazolin-4(3H)-one has been synthesized and characterized by physicochemical as well as spectral means. The synthesized Mannich and Schiff bases were screened for their preliminary antimicrobial activity against Gram-positive and Gram-negative bacterial as well as fungal strains by the determination of zone of inhibition. Mannich bases (QP1-12) were found to be more potent antibacterial agents against Gram-positive bacteria, whereas Schiff bases (QSP1-5) were more potent against Gram-negative bacteria and fungi. Minimum inhibitory concentration result demonstrated that Mannich base compound (QP7) having ortho -OH and para -COOH group showed some improvement in antibacterial activity (minimum inhibitory concentration of 48.88×10−3 μM/ml) among the tested Gram-positive organisms and it also exhibit minimum inhibitory concentration of value of 12.22×10−3 μM/ml for Klebsiella pneumoniae. The antitubercular activity of synthesized compounds against Mycobacterium tuberculosis (H37Rv) was determined using microplate alamar blue assay. Compound QP11 showed appreciable antitubercular activity (minimum inhibitory concentration of 6.49×10−3 μM/ml) which was more active than the standard drugs, ethambutol (minimum inhibitory concentration of 7.60×10−3 μM/ml) and ciprofloxacin (9.4×10−3 μM/ml). Compounds QP11, QP9, QSP1, QSP2, and QSP5 have good selective index and may be selected as a lead compound for the development of novel antitubercular agents. PMID:24302802
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A comprehensive approach to predicting chronic toxicity from acute.toxicity data was developed in which simultaneous consideration is given to concentration, degree of response, and time course of effect. onsistent endpoint (lethality) and degree of response (O%) were used to com...
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A comprehensive approach to predicting chronic toxicity from cute toxicity data was developed in which simultaneous onsideration is given to concentration, degree of response, and ime course of effect. onsistent endpoint (lethality) and degree of response (0 percent) were used to...
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Mol, Meriel; van Kan, Hendrikus J M; Schultz, Marcus J; de Jonge, Evert
2008-05-01
To study whether selective decontamination of the digestive tract (SDD) results in detectable serum tobramycin concentrations in intensive care unit (ICU) patients with acute renal failure treated with continuous venovenous hemofiltration (CVVH). Prospective, observational, single-center study in a mixed medical-surgical ICU. Adult ICU patients receiving SDD for at least 3 days and being treated with CVVH because of acute renal failure. Tobramycin serum concentrations were measured at the 3rd day after start of CVVH and every 3 days thereafter. Detectable serum concentrations of tobramycin were found in 12 (63%) of 19 patients and in 15 (58%) of the 26 samples. With a toxic tobramycin concentration defined as more than 2.0 mg/l, we found one patient with a toxic concentration of 3.0 mg/l. In three other patients tobramycin concentrations of >or=1.0 mg/l were found. In patients with acute renal failure treated with CVVH, administration of SDD with tobramycin can lead to detectable and potentially toxic serum tobramycin concentrations.
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Styczynski, Ashley R; Anwar, Khandaker N; Sultana, Habiba; Ghanem, Abdelhamid; Lurain, Nell; Chua, Aishi; Ghassemi, Mahmood; Novak, Richard M
2015-08-30
Copper has antimicrobial properties and has been studied for its activity against viruses, including HIV. Copper complexed within a phthalocyanine ring, forming copper (II) phthalocyanine sulfate (CuPcS), may have a role in microbicide development when used intravaginally. CuPcS toxicity was tested against cervical epithelial cells, TZM-BL cells, peripheral blood mononuclear cells (PBMC), and cervical explant tissues using cell viability assays. In vivo toxicity was assessed following intravaginal administration of CuPcS in female BALB/C mice and measured using a standardized histology grading system on reproductive tract tissues. Efficacy studies for preventing infection with HIV in the presence of various non-toxic concentrations of CuPcS were carried out in TZM-BL, PBMC, and cervical explant cultures using HIV-1BAL and various pseudovirus subtypes. Non-linear regression was applied to the data to determine the EC50/90 and CC50/90. CuPcS demonstrated inhibition of HIV infection in PBMCs at concentrations that were non-toxic in cervical epithelial cells and PBMCs with EC50 values of approximately 50 μg/mL. Reproductive tract tissue analysis revealed no toxicity at 100 mg/mL. Human cervical explant tissues challenged with HIV in the presence of CuPcS also revealed a dose-response effect at preventing HIV infection at non-toxic concentrations with an EC50 value of 65 μg/mL. These results suggest that CuPcS may be useful as a topical microbicide in concentrations that can be achieved in the female genital tract.
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Yang, Gui-Di; Xie, Wan-Ying; Zhu, Xi; Huang, Yi; Yang, Xiao-Jun; Qiu, Zong-Qing; Lv, Zhen-Mao; Wang, Wen-Na; Lin, Wen-Xiong
2015-10-01
Arsenite [As (III)] oxidation can be accelerated by bacterial catalysis, but the effects of the accelerated oxidation on arsenic toxicity and translocation in rice plants are poorly understood. Herein we investigated how an arsenite-oxidizing bacterium, namely Brevibacillus laterosporus, influences As (III) toxicity and translocation in rice plants. Rice seedlings of four cultivars, namely Guangyou Ming 118 (GM), Teyou Hang II (TH), Shanyou 63 (SY) and Minghui 63 (MH), inoculated with or without the bacterium were grown hydroponically with As (III) to investigate its effects on arsenic toxicity and translocation in the plants. Percentages of As (III) oxidation in the solutions with the bacterium (100%) were all significantly higher than those without (30-72%). The addition of the bacterium significantly decreased As (III) concentrations in SY root, GM root and shoot, while increased the As (III) concentrations in the shoot of SY, MH and TH and in the root of MH. Furthermore, the As (III) concentrations in the root and shoot of SY were both the lowest among the treatments with the bacterium. On the other hand, its addition significantly alleviated the As (III) toxicity on four rice cultivars. Among the treatments amended with B. laterosporus, the bacterium showed the best remediation on SY seedlings, with respect to the subdued As (III) toxicity and decreased As (III) concentration in its roots. These results indicated that As (III) oxidation accelerated by B. laterosporus could be an effective method to alleviate As (III) toxicity on rice seedlings. Copyright © 2015 Elsevier Inc. All rights reserved.
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Rodríguez, Inés; Alfonso, Amparo; Alonso, Eva; Rubiolo, Juan A; Roel, María; Vlamis, Aristidis; Katikou, Panagiota; Jackson, Stephen A; Menon, Margassery Lekha; Dobson, Alan; Botana, Luis M
2017-01-20
In 2012, Tetrodotoxin (TTX) was identified in mussels and linked to the presence of Prorocentrum minimum (P. minimum) in Greece. The connexion between TTX and P. minimum was further studied in this paper. First, the presence of TTX-producer bacteria, Vibrio and Pseudomonas spp, was confirmed in Greek mussels. In addition these samples showed high activity as inhibitors of sodium currents (I Na ). P. minimum was before associated with neurotoxic symptoms, however, the nature and structure of toxins produced by this dinoflagellate remains unknown. Three P. minimum strains, ccmp1529, ccmp2811 and ccmp2956, growing in different conditions of temperature, salinity and light were used to study the production of toxic compounds. Electrophysiological assays showed no effect of ccmp2811 strain on I Na , while ccmp1529 and ccmp2956 strains were able to significantly reduce I Na in the same way as TTX. In these samples two new compounds, m/z 265 and m/z 308, were identified and characterized by liquid chromatography tandem high-resolution mass spectrometry. Besides, two TTX-related bacteria, Roseobacter and Vibrio sp, were observed. These results show for the first time that P. minimum produce TTX-like compounds with a similar ion pattern and C9-base to TTX analogues and with the same effect on I Na .
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Speciation modeling of ammonia and other major solutes in anaerobic digesters
USDA-ARS?s Scientific Manuscript database
Anaerobic digestion of high-nitrogen wastes can be inhibited by high concentrations of un-ionized ammonia, NH**3 (aq). Understanding the toxicity of NH**3 (aq) to anaerobic digestion requires an understanding of the mechanisms controlling its concentration. Previous work on ammonia toxicity in an...
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Various models have been proposed for describing the time- and concentration-dependence of toxic effects to aquatic organisms, which would improve characterization of risks in natural systems. Selected models were evaluated using results from a study on the lethality of copper t...
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29 CFR 1915.32 - Toxic cleaning solvents.
Code of Federal Regulations, 2011 CFR
2011-07-01
... space. (2) Either natural ventilation or mechanical exhaust ventilation shall be used to remove the vapor at the source and to dilute the concentration of vapors in the working space to a concentration which is safe for the entire work period. (3) Employees shall be protected against toxic vapors by...
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Comparison of the radiological and chemical toxicity of lead
DOE Office of Scientific and Technical Information (OSTI.GOV)
Beitel, G.A.; Mott, S.
1995-03-01
This report estimates the worst-case radiological dose to an individual from ingested lead containing picocurie levels of radionuclides and then compares the calculated radiological health effects to the chemical toxic effects from that same lead. This comparison provides an estimate of the consequences of inadvertently recycling, in the commercial market, lead containing nominally undetectable concentrations of radionuclides. Quantitative expressions for the radiological and chemical toxicities of lead are based on concentrations of lead in the blood stream. The result shows that the chemical toxicity of lead is a greater health hazard, by orders of magnitude, than any probable companion radiationmore » dose.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Venkataramiah, A.; Lakshmi, G.J.; Best, C.
1981-06-01
Ammonia and chlorine were chosen for toxicity studies as they pose the greatest potential environmental threat. Acute and chronic bioassays determined the LT/sub 50/, LC/sub 50/ and the behavior of mullet (Mugil cephalus), sargassum shrimp (Latreutes focorum) and filefish (Monocanthus hispidus). The chronic bioassays were carried out mainly in sublethal concentrations of ammonia and chlorine. The findings indicate that high concentrations of ammonia and chlorine from the OTEC plants are toxic to marine animals. Also the level of toxicity is related to the species, their habitats and life stages.