Papers by Cecilia Clemedson
Alternatives to Laboratory Animals
The effects of carbon tetrachloride on neuronal development and differentiation have been studied... more The effects of carbon tetrachloride on neuronal development and differentiation have been studied. Rat embryo mid-brain micromass cultures were exposed for five days to 50, 100, 250, 500 or 1000ppm CCl4 in closed chambers. Differentiation was indicated by the formation of neuronal foci in the cultures. Effects on cell survival were estimated using a neutral red staining method. Carbon tetrachloride at 100ppm caused a drastic increase in neuronal differentiation, accompanied by a slight increase in total cell number. At 250ppm the number of differentiated foci was still elevated, but the outgrowth of neurites was markedly reduced. Neuronal differentiation and cell survival were reduced by 50% at a concentration of 430ppm. Using criteria previously defined for the identification of potentially teratogenic substances in the micromass system, CCl4 was classified as a non-teratogen. Nevertheless, the results show that a substance can cause inhibition of differentiation (reduction in neun...
Alternatives to Laboratory Animals
This review summarises some aspects of the dynamics of the evolution of toxicological test method... more This review summarises some aspects of the dynamics of the evolution of toxicological test methods based on cell biology. Within the multicentre evaluation of in vitro cytotoxicity (MEIC) programme, some general principles for validation have been proposed: a) a human database should be used as the source of reference data in the validation of new methods aimed at predicting human toxicity; b) the relevance of a test should be determined before its reliability is assessed; c) a parallel validation of methods is preferable to a serial validation; and d) toxicokinetic data should be included in the validation process to improve the predictivity of cytotoxicity test results. These toxicokinetic data can be used to extrapolate the cytotoxic in vitro concentrations to provide human toxic exposure levels. As part of test development, the cytotoxic concentration can also be compared directly with the critical toxic human blood or tissue concentration. This approach is being explored in the...
Alternatives to Laboratory Animals
The effects of carbon tetrachloride (CC14) on lipid peroxidation and respiratory activity in cent... more The effects of carbon tetrachloride (CC14) on lipid peroxidation and respiratory activity in central nervous system (CNS) cells (neurons and astrocytes) have been studied and compared with effects on hepatocytes. Cell cultures of neurons, astrocytes and hepatocytes were prepared from 8-, 14- and 15-day-old chick embryos, respectively. After appropriate intervals, each type of culture was exposed to 0, 2, 3 and 4mM CC14 in a closed-chamber system for 30 or 60 minutes. The neurons, in contrast to both the astrocytes and the hepatocytes, showed a concentration-dependent increase in lipid peroxidation. Pretreatment of astrocyte and hepatocyte cultures with phenobarbital did not increase the degree of lipid peroxidation in these cells. Also, according to protein content, the neuron cultures appeared to be the most sensitive. Respiratory activity was drastically inhibited (70%) in the hepatocyte cultures and slightly inhibited (30–35%) in the CNS cell cultures, after exposure for 60 minut...
Alternatives to Laboratory Animals
The multicentre evaluation of in vitro cytotoxicity (MEIC) study is a programme designed to evalu... more The multicentre evaluation of in vitro cytotoxicity (MEIC) study is a programme designed to evaluate the relevance of in vitro toxicity tests for predicting human toxicity, and is organised by the Scandinavian Society for Cell Toxicology. The project started in 1989 and is scheduled to be finished by June 1996. MEIC is a voluntary effort by international laboratories to test the same 50 reference chemicals in their own in vitro toxicity systems. At present, 31 laboratories have submitted results for the first 30 reference chemicals from a total of 68 in vitro cytotoxicity tests. In the definitive evaluation of the MEIC programme, these in vitro results will be compared with human lethal blood concentrations and other relevant acute systemic toxicity data, and the results will be published as a series of articles. This paper, which is the first article in this series, describes and analyses the methodologies used in the 68 tests. The origins and purities of the test chemicals, the bi...
Alternatives to Laboratory Animals
Chronic toxicity is a consequence of the persistent or progressively deteriorating dysfunction of... more Chronic toxicity is a consequence of the persistent or progressively deteriorating dysfunction of cells, organs or multiple organ systems, resulting from long-term exposure to a chemical (1). Of relevance for cosmetic products are the oral, dermal and inhalation subacute (28-day) and subchronic (90day) repeated dose studies conducted in rodents. 1. Repeated dose 28-day oral toxicity study (OECD TG 407, EC B.7). 2. Repeated dose 90-day oral toxicity study (OECD TG 408, EC B.26). 3. Repeated dose 21/28-day dermal toxicity study (OECD TG 410, EC B.9). 4. Subchronic 90-day dermal toxicity study (OECD TG 411, EC B.28). 5. Repeated dose 28-day or 14-day inhalation toxicity study (OECD TG 412, EC B.8). 6. Subchronic 90-day inhalation toxicity study (OECD TG 413, EC B.29).
Alternatives to Laboratory Animals
Short description. The Chang liver cells are cultured in paraffin-sealed 96-well microtitre plate... more Short description. The Chang liver cells are cultured in paraffin-sealed 96-well microtitre plates. Deficient outgrowth of fusiform or spindle-shaped cells is used as a criterion of cyto-inhibition. The cultures are further cultivated for 7 days and used in test d. Purpose. To be used in a test battery, with test a, b, and d.
Alternatives to Laboratory Animals
Clin Pharmacol Ther, 2008
Toxicology in Vitro an International Journal Published in Association With Bibra, Aug 1, 1999
ÐIn the MEIC study, the ®rst 30 reference chemicals were tested in 82 in vitro toxicity assays wh... more ÐIn the MEIC study, the ®rst 30 reference chemicals were tested in 82 in vitro toxicity assays while the last 20 chemicals were tested in 67 assays. To increase understanding of the performance of in vitro toxicity tests, these two subsets of results were compared by principal components analyses (PCA) combined with a``random probe'' analysis of ®ve key methodological factors, that is, the results from all pairs of methods which were similar in all other respects than the analysed factor were systematically compared by linear regression. This paper is an overview of these published comparisons, and also includes a new``random probe'' analysis of another segment of the same MEIC results, namely tests of all 50 reference chemicals by 61 of the methods. A PCA indicated high general similarity (around 80%) of all the results from the 61 methods. According to the new``random probe'' analysis, this similarity must depend on the high correlation of results from assays with dierent cell types (mean R 2 0.81) and/ or dierent viability endpoints (mean R 2 0.85). Main factors contributing to the 20% dissimilarity of results were dierent exposure times and the use of phylogenetically distant test objects in the non-analogous ecotoxicological assays. As expected, the new analysis of the 61 methods gave roughly similar results as the previous``random probe'' analyses of the other two segments of the data. Findings support the basal cytotoxicity concept and will improve future in vitro toxicity testing. This testing will probably need assays with varied exposure times. As judged from the similarity of the results, simple assays with cell lines may replace complicated primary culture systems for many testing purposes (e.g. screening).
ALTEX: Alternativen zu Tierexperimenten
ACuteTox is an integrated project under the EU-FP6 with the aim to develop a simple and robust in... more ACuteTox is an integrated project under the EU-FP6 with the aim to develop a simple and robust in vitro testing strategy for prediction of human acute systemic toxicity, which could replace animal tests used for regulatory purposes. Studies show good correlation of over 70% between in vitro basal cytotoxicity and rodent LD50 values or human lethal blood concentrations. However, a number of discrepancies occur which result in misclassification. ACuteTox aims to identify factors that can eliminate these misclassifications. The outliers in the in vitro/in vivo correlation will be evaluated in order to introduce further parameters (ADE, metabolism and organ specificity), which might improve the correlation. Integration of alerts and correctors in a prediction algorithm, together with implementation of medium throughput approaches, would allow establishment of a new testing strategy to better predict toxic classification.
Alternatives to laboratory animals : ATLA
The Multicenter Evaluation of In Vitro Cytotoxicity (MEIC) programme provided a battery of three ... more The Multicenter Evaluation of In Vitro Cytotoxicity (MEIC) programme provided a battery of three basal cytotoxicity tests with a good (R2 = 0.77) prediction of human acute lethal blood concentrations. The predictive power of this battery would be considerably improved by the addition of new supplementary in vitro tests. The development of these new tests will be facilitated by a close coupling of test development to evaluation. The Cytotoxicology Laboratory, Uppsala (CTLU), is therefore inviting all interested in vitro toxicologists to take part in the Evaluation-guided Development of In Vitro Toxicity and Toxicokinetic Tests (EDIT). All EDIT activities (subprojects) will be designed on a case-by-case basis, but will follow a common pattern. The CTLU will use the accumulated MEIC/EDIT data, and its experience from the previous MEIC evaluation, to suggest priority areas, i.e. the need for certain in vitro toxicity data/tests as supplements to existing in vitro models/batteries on hum...
Clinical pharmacology and therapeutics, 2008
ACuteTox (optimization and prevalidation of an in vitro test strategy for predicting human acute ... more ACuteTox (optimization and prevalidation of an in vitro test strategy for predicting human acute toxicity) is an integrated European Union project under the Sixth Framework Programme with the aim of demonstrating that animal tests for acute systemic toxicity currently used for regulatory purposes could be replaced by a combination of alternative assays. Validated alternative test methods are urgently required for safety toxicology testing of chemicals, cosmetics, and drugs.
Alternatives to laboratory animals : ATLA, 2007
The ACuteTox project is designed to replace animal testing for acute systemic toxicity, as is wid... more The ACuteTox project is designed to replace animal testing for acute systemic toxicity, as is widely used today for regulatory purposes, by using in vitro and in silico alternatives. In spite of the fact that earlier studies on acute systemic toxicity demonstrated a good correlation between in vitro basal cytotoxicity data (the 50% inhibitory concentration [IC50]) in human cell lines and rodent LD50 values, and an even better correlation between IC50 values and human lethal blood concentrations, very few non-animal tests have been accepted for general use. Therefore, the aim of the ACuteTox project is to adapt new testing strategies, for example, the implementation of new endpoints and new cell systems for toxicity screening, organ-specific models, metabolism-dependent toxicity, tissue absorption, distribution and excretion, and computer-based prediction models. A new database, AcuBase, containing descriptions and results of in vitro tests of the 97 reference chemicals, as well as t...
Alternatives to laboratory animals : ATLA, 2005
Page 1. 1 Acute toxicity Laura Gribaldo1, Alessandra Gennari1, Karen Blackburn2, Cecilia Clemedso... more Page 1. 1 Acute toxicity Laura Gribaldo1, Alessandra Gennari1, Karen Blackburn2, Cecilia Clemedson3, ... MC, Chesné, C., Clothier, R., Cottin, M., Curren, R., Daniel-Szolgay, E., Dierickx, P., Ferro, M., Fiskesjö, G., Garza-Ocanas, L., Gómez-Lechón, MJ, ...
Alternatives to laboratory animals : ATLA
The relevance of the pulsed field gel electrophoresis (PFGE) assay for the estimation of the DNA ... more The relevance of the pulsed field gel electrophoresis (PFGE) assay for the estimation of the DNA damaging effects of chemicals was studied. Four chemicals were randomly chosen from the list of 50 Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) reference chemicals with known human acute systemic toxicity: acetylsalicylic acid, paracetamol, ethylene glycol and sodium chloride. Human fibroblasts (VH-10) were used as a model system. For the estimation of cytotoxic effect, cell monolayers were treated with chemicals for 24 hours. Cloning efficiency (colony-forming ability) at different concentrations of the test chemicals was estimated, and the 50% inhibitory concentration (IC50) was determined. The IC50 values obtained demonstrated a correlation with human lethal blood concentrations. The induction of DNA double-strand breaks, measured by PFGE as the fraction of activity released, was detected after treatment with paracetamol. However, the other three chemicals tested mainly indu...
Alternatives to laboratory animals : ATLA
The aim of the two studies presented in this paper was to further improve the predictability of t... more The aim of the two studies presented in this paper was to further improve the predictability of the original Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) in vitro test battery for acute systemic toxicity. In the first study, whether a protein-free cytotoxicity assay could improve the prediction of human acute systemic toxicity was investigated. The cytotoxicity of 39 MEIC reference chemicals was measured by the neutral red uptake inhibition test after 30 minutes in phosphate-buffered saline (PBS), with hepatoma-derived Fa32 cells. The results were compared with the corresponding values obtained in complete culture medium, including 10% fetal calf serum. Mercuric chloride and hexachlorophene were much more cytotoxic in PBS, as was the case, to a lesser extent, for seven other chemicals. Potassium cyanide and eight other chemicals were less cytotoxic in PBS than in complete culture medium, probably because of poor physiological conditions. The correlation between the cytotox...
Alternatives to laboratory animals : ATLA, 2005
Alternatives to laboratory animals : ATLA
The aim of the Evaluation-guided Development of new In Vitro Test Batteries (EDIT) multicentre pr... more The aim of the Evaluation-guided Development of new In Vitro Test Batteries (EDIT) multicentre programme is to establish and validate in vitro tests relevant to toxicokinetics and for organ-specific toxicity, to be incorporated into optimal test batteries for the estimation of human acute systemic toxicity. The scientific basis of EDIT is the good prediction of human acute toxicity obtained with three human cell line tests (R(2) = 0.77), in the Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) programme. However, the results from the MEIC study indicated that at least two other types of in vitro test ought to be added to the existing test battery to improve the prediction of human acute systemic toxicity - to determine key kinetic events (such as biotransformation and passage through biological barriers), and to predict crucial organ-specific mechanisms not covered by the tests in the MEIC battery. The EDIT programme will be a case-by-case project, but the establishment and val...
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Papers by Cecilia Clemedson