| 1. |
- Krebs, Alice, et al.
(författare)
-
Template for the Description of Cell-Based Toxicological Test Methods to Allow Evaluation and Regulatory Use of the Data
- 2019
-
Ingår i: Altex. - : ALTEX Edition. - 1868-596X .- 1868-8551. ; 36:4, s. 682-699
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Only few cell-based test methods are described by Organisation for Economic Co-operation and Development (OECD) test guidelines or other regulatory references (e.g., the European Pharmacopoeia). The majority of toxicity tests still falls into the category of non-guideline methods. Data from these tests may nevertheless be used to support regulatory decisions or to guide strategies to assess compounds (e.g., drugs, agrochemicals) during research and development if they fulfill basic requirements concerning their relevance, reproducibility and predictivity. Only a method description of sufficient clarity and detail allows interpretation and use of the data. To guide regulators faced with increasing amounts of data from non-guideline studies, the OECD formulated Guidance Document 211 (GD211) on method documentation for the purpose of safety assessment. As GD211 is targeted mainly at regulators, it leaves scientists less familiar with regulation uncertain as to what level of detail is required and how individual questions should be answered. Moreover, little attention was given to the description of the test system (i.e., cell culture) and the steps leading to it being established in the guidance. To address these issues, an annotated toxicity test method template (ToxTemp) was developed (i) to fulfill all requirements of GD211, (ii) to guide the user concerning the types of answers and detail of information required, (iii) to include acceptance criteria for test elements, and (iv) to define the cells sufficiently and transparently. The fully annotated ToxTemp is provided here, together with reference to a database containing exemplary descriptions of more than 20 cell-based tests.
|
|
| 2. |
- Leist, Marcel, et al.
(författare)
-
Adverse outcome pathways : opportunities, limitations and open questions
- 2017
-
Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 91:11, s. 3477-3505
-
Tidskriftsartikel (refereegranskat)abstract
- Adverse outcome pathways (AOPs) are a recent toxicological construct that connects, in a formalized, transparent and quality-controlled way, mechanistic information to apical endpoints for regulatory purposes. AOP links a molecular initiating event (MIE) to the adverse outcome (AO) via key events (KE), in a way specified by key event erelationships (KER). Although this approach to formalize mechanistic toxicological information only started in 2010, over 200 AOPs have already been established. At this stage, new requirements arise, such as the need for harmonization and re-assessment, for continuous updating, as well as for alerting about pitfalls, misuses and limits of applicability. In this review, the history of the AOP concept and its most prominent strengths are discussed, including the advantages of a formalized approach, the systematic collection of weight of evidence, the linkage of mechanisms to apical end points, the examination of the plausibility of epidemiological data, the identification of critical knowledge gaps and the design of mechanistic test methods. To prepare the ground for a broadened and appropriate use of AOPs, some widespread misconceptions are explained. Moreover, potential weaknesses and shortcomings of the current AOP rule set are addressed (1) to facilitate the discussion on its further evolution and (2) to better define appropriate vs. less suitable application areas. Exemplary toxicological studies are presented to discuss the linearity assumptions of AOP, the management of event modifiers and compensatory mechanisms, and whether a separation of toxicodynamics from toxicokinetics including metabolism is possible in the framework of pathway plasticity. Suggestions on how to compromise between different needs of AOP stakeholders have been added. A clear definition of open questions and limitations is provided to encourage further progress in the field.
|
|
| 3. |
- Warnke, Clemens, et al.
(författare)
-
Cerebrospinal Fluid JC Virus Antibody Index for Diagnosis of Natalizumab-Associated Progressive Multifocal Leukoencephalopathy
- 2014
-
Ingår i: Annals of Neurology. - : Wiley. - 0364-5134 .- 1531-8249. ; 76:6, s. 792-801
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Progressive multifocal leukoencephalopathy (PML), caused by JC virus (JCV), can occur in patients receiving natalizumab for multiple sclerosis (MS). JCV detection by quantitative polymerase chain reaction (qPCR) in cerebrospinal fluid (CSF), or brain biopsy, is required for probable or definite diagnosis of PML. However, in some patients only low levels of JCV DNA (<100 copies/ml) are present in CSF, making the diagnosis challenging. Our objective was to assess the complementary value of a CSF JCV antibody index (AI(JCV)) in the diagnosis of natalizumab-associated PML.Methods: AI(JCV) was assessed in 37 cases of natalizumab-associated PML and 89 MS-patients treated with natalizumab without PML. Sera and CSF were tested in a capture enzyme-linked immunosorbent assay, using JCV-VP1 fused to glutathione S-transferase as antigen. Albumin levels and total immunoglobulin G concentration were determined by immunonephelometry, and the AI(JCV) was calculated as published.Results:Twenty-six of 37 (70%) patients with natalizumab-associated PML exhibited an AI(JCV) > 1.5, whereas this was seen in none of the controls (p < 0.0001). At time of the first positive qPCR for JCV DNA, 11 of 20 (55%) patients with natalizumab-associated PML had an AI(JCV) > 1.5. JCV DNA levels of <100 copies/ml were seen in 14 (70%) of these 20 patients, of whom 8 (57%) demonstrated an AI(JCV) > 1.5.Interpretation: Determination of the AI(JCV) could be an added tool in the diagnostic workup for PML and should be included in the case definition of natalizumab-associated PML. Ann Neurol 2014;76:792-801
|
|
| 4. |
- Warnke, Clemens, et al.
(författare)
-
Natalizumab exerts a suppressive effect on surrogates of B cell function in blood and CSF
- 2015
-
Ingår i: Multiple Sclerosis Journal. - : Sage Publications. - 1352-4585 .- 1477-0970. ; 21:8, s. 1036-1044
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Natalizumab for multiple sclerosis (MS) increases the risk of progressive multifocal leukoencephalopathy (PML). Objective: We aimed to assess the effect of natalizumab on cellular composition and functional B cell parameters including patients with natalizumab-associated PML (n=37). Methods: Cellular composition by flow cytometry, levels of immunoglobulin (Ig)G/IgM by immunonephelometry, and oligoclonal bands by isoelectric focusing were studied in blood and cerebrospinal fluid. Results: In MS patients treated with natalizumab without PML (n=59) the proportion of CD19+ B cells was higher in blood, but lower in cerebrospinal fluid compared with MS patients not treated with natalizumab (n=17). The CD4/CD8-ratio in cerebrospinal fluid was lower, and IgG and IgM levels as well as the IgG index dropped in longitudinal samples during natalizumab therapy. Oligoclonal bands persisted, but the total amount of the intrathecally produced IgG fraction, and the polyclonal intrathecal IgG reactivity to measles, rubella, and zoster declined. At the time of diagnosis of PML patients with natalizumab-associated PML had low total IgG levels in blood and cerebrospinal fluid. Conclusions: Natalizumab impacts B and T cell distribution and exerts an inhibitory effect on surrogates of B cell function in periphery and in cerebrospinal fluid, potentially contributing to the increased risk of developing PML.
|
|
| 5. |
|
|
| 6. |
- Högberg, Helena T., 1975-, et al.
(författare)
-
Gene expression as a sensitive endpoint to evaluate cell differentiation andmaturation of the developing central nervous system in primary cultures of ratcerebellar granule cells (CGCs) exposed to pesticides
- 2009
-
Ingår i: Toxicology and Applied Pharmacology. - : Elsevier BV. - 0041-008X .- 1096-0333. ; 235, s. 268-286
-
Tidskriftsartikel (refereegranskat)abstract
- The major advantage of primary neuronal cultures for developmental neurotoxicity (DNT) testing is their ability to replicate the crucial stages of neurodevelopment. In our studies using primary culture of cerebellar granule cells (CGCs) we have evaluated whether the gene expression relevant to the most critical developmental processes such as neuronal differentiation (NF-68 and NF-200) and functional maturation (NMDA and GABA presence of neural precursor cells (nestin and Sox10) could be used as an endpoint for in vitro DNT. The expression of these genes was assessed after exposure to various pesticides (paraquat parathion, dichlorvos, pentachlorophenol and cycloheximide) that could induce developmental neurotoxicity through different mechanisms. All studied pesticides signi different stages of neuronal and/or glial cell development and maturation. The most signi observed after exposure to paraquat and parathion (i.e. down-regulation of mRNA expression of NF-68 and NF-200, NMDA and GABA expression of NF-68 and GABA as signi astrocyte marker (S100 multiple pathways of neurodevelopment can be identi in different stages of cell development and maturation, and that gene expression could be used as a sensitive endpoint for initial screening to identify the compounds with the potential to cause developmental neurotoxicity. A receptors), proliferation and differentiation of astrocytes (GFAP and S100β) as well as theficantly modified the expression of selected genes, related to theficant changes wereA receptors). Similarly, dichlorvos affected mainly neurons (decreased mRNAA receptors) whereas cycloheximide had an effect on neurons and astrocytes,ficant decreases in the mRNA expression of both neurofilaments (NF-68 and NF-200) and theβ) were observed. Our results suggest that toxicity induced by pesticides that targetfied by studying expression of genes that are involved
|
|
| 7. |
- Högberg, Helena T., 1975-, et al.
(författare)
-
mRNA Expression is a Relevant Tool to Identify Developmental Neurotoxicants Using an In Vitro Approach
- 2009
-
Ingår i: Toxicological Sciences. - : Oxford university press. - 1096-6080 .- 1096-0929. ; 113:1, s. 95-115
-
Tidskriftsartikel (refereegranskat)abstract
- So far, only a few industrial chemicals have been identified as developmental neurotoxicants. Because the current developmental neurotoxicity (DNT) guideline (Organisation for Economic Cooperation and Development TG 426) is based entirely on in vivo studies that are both time consuming and costly, there is a need to develop alternative in vitro methods for initial screening to prioritize chemicals for further DNT testing. In this study, gene expression at the mRNA level was evaluated to determine whether this could be a suitable endpoint to detect potential developmental neurotoxicants. Primary cultures of rat cerebellar granule cells (CGCs) were exposed to well known (developmental) neurotoxicants (methyl mercury chloride, lead chloride, valproic acid, and tri-methyl tin chloride) for different time periods. A significant downregulation of the mRNA level for the neuronal markers (NF- 68, NF-200, N-methyl D-aspartate glutamate receptor, and gamma amino butyric acid receptor) was observed after exposure to methyl mercury chloride, valproic acid, and tri-methyl tin chloride. Moreover, a significant increase of the neural precursor marker nestin mRNA was also observed. The mRNA expression of the astrocytic markers (glial fibrillary acidic protein [GFAP] and S100b) was unchanged. In contrast, exposure to lead chloride significantly decreased the mRNA level of the astrocytic marker GFAP, whereas the neuronal markers were less affected. These results suggest that gene expression could be used as a sensitive tool for the initial identification of DNT effects induced by different mechanisms of toxicity in both cell types (neuronal and glial) and at various stages of cell development and maturation.
|
|
| 8. |
|
|
| 9. |
- Lill, Christina M., et al.
(författare)
-
Closing the case of APOE in multiple sclerosis : no association with disease risk in over 29 000 subjects
- 2012
-
Ingår i: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 49:9, s. 558-562
-
Tidskriftsartikel (refereegranskat)abstract
- Background Single nucleotide polymorphisms (SNPs) rs429358 (ε4) and rs7412 (ε2), both invoking changes in the amino-acid sequence of the apolipoprotein E (APOE) gene, have previously been tested for association with multiple sclerosis (MS) risk. However, none of these studies was sufficiently powered to detect modest effect sizes at acceptable type-I error rates. As both SNPs are only imperfectly captured on commonly used microarray genotyping platforms, their evaluation in the context of genome-wide association studies has been hindered until recently.Methods We genotyped 12 740 subjects hitherto not studied for their APOE status, imputed raw genotype data from 8739 subjects from five independent genome-wide association studies datasets using the most recent high-resolution reference panels, and extracted genotype data for 8265 subjects from previous candidate gene assessments.Results Despite sufficient power to detect associations at genome-wide significance thresholds across a range of ORs, our analyses did not support a role of rs429358 or rs7412 on MS susceptibility. This included meta-analyses of the combined data across 13 913 MS cases and 15 831 controls (OR=0.95, p=0.259, and OR 1.07, p=0.0569, for rs429358 and rs7412, respectively).Conclusion Given the large sample size of our analyses, it is unlikely that the two APOE missense SNPs studied here exert any relevant effects on MS susceptibility.
|
|
| 10. |
|
|
| 11. |
- Ortega, Pablo, et al.
(författare)
-
Improving Arctic Weather and Seasonal Climate Prediction : Recommendations for Future Forecast Systems Evolution from the European Project APPLICATE
- 2022
-
Ingår i: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 103:10, s. E2203-E2213
-
Tidskriftsartikel (refereegranskat)abstract
- The Arctic environment is changing, increasing the vulnerability of local communities and ecosystems, and impacting its socio-economic landscape. In this context, weather and climate prediction systems can be powerful tools to support strategic planning and decision-making at different time horizons. This article presents several success stories from the H2020 project APPLICATE on how to advance Arctic weather and seasonal climate prediction, synthesizing the key lessons learned throughout the project and providing recommendations for future model and forecast system development.
|
|
| 12. |
- Sawcer, Stephen, et al.
(författare)
-
Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis
- 2011
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 476:7359, s. 214-219
-
Tidskriftsartikel (refereegranskat)abstract
- Multiple sclerosis is a common disease of the central nervous system in which the interplay between inflammatory and neurodegenerative processes typically results in intermittent neurological disturbance followed by progressive accumulation of disability. Epidemiological studies have shown that genetic factors are primarily responsible for the substantially increased frequency of the disease seen in the relatives of affected individuals, and systematic attempts to identify linkage in multiplex families have confirmed that variation within the major histocompatibility complex (MHC) exerts the greatest individual effect on risk. Modestly powered genome-wide association studies (GWAS) have enabled more than 20 additional risk loci to be identified and have shown that multiple variants exerting modest individual effects have a key role in disease susceptibility. Most of the genetic architecture underlying susceptibility to the disease remains to be defined and is anticipated to require the analysis of sample sizes that are beyond the numbers currently available to individual research groups. In a collaborative GWAS involving 9,772 cases of European descent collected by 23 research groups working in 15 different countries, we have replicated almost all of the previously suggested associations and identified at least a further 29 novel susceptibility loci. Within the MHC we have refined the identity of the HLA-DRB1 risk alleles and confirmed that variation in the HLA-A gene underlies the independent protective effect attributable to the class I region. Immunologically relevant genes are significantly overrepresented among those mapping close to the identified loci and particularly implicate T-helper-cell differentiation in the pathogenesis of multiple sclerosis.
|
|
| 13. |
|
|
| 14. |
- Schmidt, Bela Z., et al.
(författare)
-
In vitro acute and developmental neurotoxicity screening : an overview of cellular platforms and high-throughput technical possibilities
- 2017
-
Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 91:1, s. 1-33
-
Forskningsöversikt (refereegranskat)abstract
- Neurotoxicity and developmental neurotoxicity are important issues of chemical hazard assessment. Since the interpretation of animal data and their extrapolation to man is challenging, and the amount of substances with information gaps exceeds present animal testing capacities, there is a big demand for in vitro tests to provide initial information and to prioritize for further evaluation. During the last decade, many in vitro tests emerged. These are based on animal cells, human tumour cell lines, primary cells, immortalized cell lines, embryonic stem cells, or induced pluripotent stem cells. They differ in their read-outs and range from simple viability assays to complex functional endpoints such as neural crest cell migration. Monitoring of toxicological effects on differentiation often requires multiomics approaches, while the acute disturbance of neuronal functions may be analysed by assessing electrophysiological features. Extrapolation from in vitro data to humans requires a deep understanding of the test system biology, of the endpoints used, and of the applicability domains of the tests. Moreover, it is important that these be combined in the right way to assess toxicity. Therefore, knowledge on the advantages and disadvantages of all cellular platforms, endpoints, and analytical methods is essential when establishing in vitro test systems for different aspects of neurotoxicity. The elements of a test, and their evaluation, are discussed here in the context of comprehensive prediction of potential hazardous effects of a compound. We summarize the main cellular characteristics underlying neurotoxicity, present an overview of cellular platforms and read-out combinations assessing distinct parts of acute and developmental neurotoxicology, and highlight especially the use of stem cell-based test systems to close gaps in the available battery of tests.
|
|
