| 1. |
- Adolfsson-Erici, Margaretha, et al.
(författare)
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A flow-through passive dosing system for continuously supplying aqueous solutions of hydrophobic chemicals to bioconcentration and aquatic toxicity tests
- 2012
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 86:6, s. 593-599
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Tidskriftsartikel (refereegranskat)abstract
- A continuous supply of water with defined stable concentrations of hydrophobic chemicals is a requirement in a range of laboratory tests such as the OECD 305 protocol for determining the bioconcentration factor in fish. Satisfying this requirement continues to be a challenge, particularly for hydrophobic chemicals. Here we present a novel solution based on equilibrium passive dosing. It employs a commercially available unit consisting of similar to 16000 polydimethylsiloxane (PDMS) tubes connected to two manifolds. The chemicals are loaded into the unit by repeatedly perfusing it with a methanol solution of the substances that is progressively diluted with water. Thereafter the unit is perfused with water and the chemicals partition from the unit into the water. The system was tested with nine chemicals with logK(ow) ranging from 4.1 to 6.3. The aqueous concentrations generated were shown to be largely independent of the water flow rate, and the unit to unit reproducibility was within a factor of similar to 2. In continuous flow experiments the aqueous concentrations of most of the study chemicals remained constant over 8 d. A model was assembled that allows prediction of the operating characteristics of the system from the logKow or PDMS/water partition coefficient of the chemical. The system is a simple, safe, predictable and flexible tool that generates stable aqueous concentrations of hydrophobic chemicals.
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| 2. |
- Adolfsson-Erici, Margaretha, et al.
(författare)
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In-vivo passive sampling to measure elimination kinetics in bioaccumulation tests
- 2012
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 88:1, s. 62-68
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Tidskriftsartikel (refereegranskat)abstract
- The application of in-tissue passive sampling to quantify chemical kinetics in fish bioconcentration experiments was investigated. A passive sampler consisting of an acupuncture needle covered with a PDMS tube was developed together with a method for its deployment in rainbow trout. The time to steady state for chemical uptake into the passive sampler was >1 d, so it was employed as a kinetically limited sampler with a deployment time of 2 h. The passive sampler was employed in parallel with the established whole tissue extraction method to study the elimination kinetics of 10 diverse chemicals in rainbow trout. 4-n-nonylphenol and 2,4,6-tri-tert-butylphenol were close to or below the limit of quantification in the sampler. For chlorpyrifos, musk xylene, hexachlorobenzene, 2,5-dichlorobiphenyl and p,p'-DDT. the elimination rate constants determined with the passive sampler method and the established method agreed within 18%. Poorer agreement (35%) was observed for 2,3,4-trichloroanisole and p-diisopropylbenzene because fewer data were obtained with the passive sampling method due to its lower sensitivity. The work shows that in-tissue passive sampling can be employed to measure contaminant elimination kinetics in fish. This opens up the possibility of studying contaminant kinetics in individual fish, thereby reducing the fish requirements and analytical costs for the determination of bioconcentration factors.
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| 3. |
- Adolfsson-Erici, Margaretha, et al.
(författare)
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Internal Benchmarking Improves Precision and Reduces Animal Requirements for Determination of Fish Bioconcentration Factors
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:15, s. 8205-8211
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Tidskriftsartikel (refereegranskat)abstract
- The enactment of new chemical regulations has generated a large need for the measurement of the fish bioconcentration factor (BCF). Past experience shows that the BCF determination lacks precision, requires large numbers of fish, and is costly. A new protocol was tested that shortens the experiment from up to 12 weeks for existing protocols to 2 weeks and reduces the number of fish by a factor of 5, while introducing internal benchmarking for the BCF determination. Rainbow trout were simultaneously exposed to 11 chemicals. The BCFs were quantified using one of the test chemicals, musk xylene, as a benchmark. These were compared with BCFs measured in a parallel experiment based on the OECD 305 guideline. The agreement was <20% for five chemicals and between 20%-25% for two further, while two chemicals lay outside the BCF operating window of the experiment and one was lost due to analytical difficulties. This agreement is better than that observed in a BCF Gold Standard Database. Internal benchmarking allows the improvement of the precision of BCF determination in parallel to large reduction in costs and fish requirements.
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| 4. |
- Adolfsson-Erici, Margaretha, et al.
(författare)
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Measuring bioconcentration factors in fish using exposure to multiple chemicals and internal benchmarking to correct for growth dilution
- 2012
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 31:8, s. 1853-1860
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Tidskriftsartikel (refereegranskat)abstract
- Modern chemical legislation requires measuring the bioconcentration factor (BCF) of large numbers of chemicals in fish. The BCF must be corrected for growth dilution, because fish growth rates vary between laboratories. Two hypotheses were tested: (1) that BCFs of multiple chemicals can be measured simultaneously in one experiment, and (2) that internal benchmarking using a conservative test substance in the chemical mixture can be used to correct for growth dilution. Bioconcentration experiments were conducted following major elements of the OECD 305 guideline. Fish were simultaneously exposed to 11 chemicals selected to cover a range of BCFs and susceptibility to biotransformation. A method was developed to calculate the growth-corrected elimination rate constant from the concentration ratio of the analyte and a benchmarking chemical for which growth dilution dominated other elimination mechanisms. This method was applied to the experimental data using hexachlorobenzene as the benchmarking chemical. The growth dilution correction lowered the apparent elimination rate constants by between 5% and a factor of four for eight chemicals, while for two chemicals the growth-corrected elimination rate constant was not significantly different from zero. The benchmarking method reduced the uncertainty in the elimination rate constant compared to the existing method for growth dilution correction. The BCFs from exposing fish to 10 chemicals at once were consistent with BCF values from single-chemical exposures from the literature, supporting hypothesis 1. Environ. Toxicol. Chem. 2012; 31: 18531860. (c) 2012 SETAC
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| 5. |
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| 6. |
- Balk, Lennart, et al.
(författare)
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Widespread episodic thiamine deficiency in Northern Hemisphere wildlife
- 2016
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Many wildlife populations are declining at rates higher than can be explained by known threats to biodiversity. Recently, thiamine (vitamin B-1) deficiency has emerged as a possible contributing cause. Here, thiamine status was systematically investigated in three animal classes: bivalves, ray-finned fishes, and birds. Thiamine diphosphate is required as a cofactor in at least five life-sustaining enzymes that are required for basic cellular metabolism. Analysis of different phosphorylated forms of thiamine, as well as of activities and amount of holoenzyme and apoenzyme forms of thiaminedependent enzymes, revealed episodically occurring thiamine deficiency in all three animal classes. These biochemical effects were also linked to secondary effects on growth, condition, liver size, blood chemistry and composition, histopathology, swimming behaviour and endurance, parasite infestation, and reproduction. It is unlikely that the thiamine deficiency is caused by impaired phosphorylation within the cells. Rather, the results point towards insufficient amounts of thiamine in the food. By investigating a large geographic area, by extending the focus from lethal to sublethal thiamine deficiency, and by linking biochemical alterations to secondary effects, we demonstrate that the problem of thiamine deficiency is considerably more widespread and severe than previously reported.
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| 7. |
- Balk, Lennart, et al.
(författare)
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Wild birds of declining European species are dying from a thiamine deficiency syndrome.
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 106:29, s. 12001-12006
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Tidskriftsartikel (refereegranskat)abstract
- Wild birds of several species are dying in large numbers from an idiopathic paralytic disease in the Baltic Sea area. Here, we demonstrate strong relationships between this disease, breeding failure, and thiamine (vitamin B(1)) deficiency in eggs, pulli, and full-grown individuals. Thiamine is essential for vertebrates, and its diphosphorylated form functions as a cofactor for several life sustaining enzymes, whereas the triphosphorylated form is necessary for the functioning of neuronal membranes. Paralyzed individuals were remedied by thiamine treatment. Moreover, thiamine deficiency and detrimental effects on thiamine-dependent enzymes were demonstrated in the yolk, liver, and brain. We propose that the mortality and breeding failure are part of a thiamine deficiency syndrome, which may have contributed significantly to declines in many bird populations during the last decades.
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| 8. |
- Eriksson, Gun, 1953-
(författare)
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Astroglial Cells : Role in Neurodegenerative-Inflammatory Processes in the Central Nervous System
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Inflammatory processes, mediated by the pro-inflammatory cytokines interleukin (IL) -1a/b, tumor necrosis factora(TNFa), IL-6 and excitotoxic actions of glutamate, are proposed to be implicated in neurodegenerative diseases, such as Alzheimer's disease.A neurotoxic fragment ofb-amyloid,bA25-35, was shown to induce a reactive phenotype of primary astrocytes and microglial cells in a time-dependent manner. The morphological changes were found to coincide with a transient expression of IL-1band a sustained increased IL-1aand IL-6 expression as determined by reverse transcription and polymerase chain reaction analysis of RNA extracted from treated and untreated cells.bA25-35 induced cytokine expression in astroglial cells from IL-1 receptor type I (IL-1RI)-deficient cultures, showed a hypersensitive IL-1aresponse and a decreased IL-6 response. Thus it was concluded that the IL-1RI is necessary for full scale induction of IL-6. Expression of IL-6 and TNFain the absence of a signalling IL-1 receptor may be induced by reactive oxygen species and/or by activation of NFkB. The IL-1aincrease may reflect a missing transcriptional feed-back regulation involving the IL-1RI.The role of IL-1 receptor accessory protein (IL-1RAcP) in IL-1binduced signalling was investigated in astroglial cultures from IL-1RAcP deficient mice. IL-1bhad no effect on nuclear NFkB binding activity suggesting that IL-1RAcP is necessary for NFkB activation. By use of specific antibodies it was shown that the activated NFkB complex consisted of p50 and possibly p52 or RelB, NFkB related proteins, respectively.The excitatory amino acid glutamate was shown to stimulate respiratory activity in primary astroglial cell cultures. This effect was found to be correlated to the Na+-dependent high affinity glutamate uptake and an increased Na+/K+-ATPase activity since it could be blocked by ouabain and mimiced by gramicidin.Carbon tetrachloride (CCl4) and n-hexane, two neurotoxic organic solvents, were shown to interfere with cAMP formation in primary rat astroglial cells. In addition, both solvents decreased basal and glutamate induced increase in respiratory activity an observation which may reflect both a decreased Na+/K+-ATPase activity and a reduction of high-affinity glutamate uptake.
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| 9. |
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| 10. |
- Hansson, Tomas, et al.
(författare)
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Cytological and biochemical biomarkers in adult female perch (Perca fluviatilis) in a chronically polluted gradient in the Stockholm recipient (Sweden)
- 2014
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X .- 1879-3363. ; 81:1, s. 27-40
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Tidskriftsartikel (refereegranskat)abstract
- By measuring a battery of cytological and biochemical biomarkers in adult female perch (Perca fluviatilis), the city of Stockholm (Sweden) was investigated as a point source of anthropogenic aquatic pollution. The investigation included both an upstream gradient, 46 km westwards through Lake Malaren, and a downstream gradient, 84 km eastwards through the Stockholm archipelago. Indeed, there was a graded response for most of the biomarkers and for the muscle concentrations of Sigma PBDE, four organotin compounds and PFOS in the perch. The results indicated severe pollution in central Stockholm, with poor health of the perch, characterised by increased frequency of micronucleated erythrocytes, altered liver apoptosis, increased liver catalase activity, decreased brain aromatase activity, and decreased liver lysosomal membrane stability. Some biomarker responses were lowest in the middle archipelago and increased again eastwards, indicating a second, partly overlapping, gradient of toxic effects from the Baltic Sea.
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