The large amount of existing nanomaterials demands rapid and reliable methods for testing their potential toxicological effect on human health, preferably by means of relevant in vitro techniques in order to reduce testing on animals. Combining high throughput workflows with automated high content imaging techniques allows deriving much more information from cell-based assays than the typical readouts (i.e.
View Article and Find Full Text PDFThe fields of toxicology and chemical risk assessment seek to reduce, and eventually replace, the use of animals for the prediction of toxicity in humans. In this context, physiologically based kinetic (PBK) modelling based on and kinetic data has the potential to a play significant role in reducing animal testing, by providing a methodology capable of incorporating human data to facilitate the development of to extrapolation of hazard information. In the present article, we discuss the challenges in: 1) applying PBK modelling to support regulatory decision making under the toxicology and risk-assessment paradigm shift towards animal replacement; 2) constructing PBK models without animal kinetic data, while relying solely on or methods for model parameterization; and 3) assessing the validity and credibility of PBK models built largely using non-animal data.
View Article and Find Full Text PDFThe Virtual Cell Based Assay (VCBA) is an in silico model that simulates the biokinetics of chemicals in in vitro test systems. Simulations by the VCBA can indicate the degree to which the bioavailable concentration varies across chemicals and experimental conditions, thereby providing important contextual information when comparing the results of different in vitro toxicity experiments. The simulated results can also be used to support in vitro to in vivo extrapolation of toxicity data, especially when the VCBA is coupled to a physiologically based kinetic model.
View Article and Find Full Text PDFBackground: An increasing number of manufactured nanomaterials (NMs) are being used in industrial products and need to be registered under the REACH legislation. The hazard characterisation of all these forms is not only technically challenging but resource and time demanding. The use of non-testing strategies like read-across is deemed essential to assure the assessment of all NMs in due time and at lower cost.
View Article and Find Full Text PDFManufactured nanomaterials (MNMs) selected from a library of over 120 different MNMs with varied compositions, sizes, and surface coatings were tested by four different laboratories for toxicity by high-throughput/-content (HT/C) techniques. The selected particles comprise 14 MNMs composed of CeO, Ag, TiO, ZnO and SiO with different coatings and surface characteristics at varying concentrations. The MNMs were tested in different mammalian cell lines at concentrations between 0.
View Article and Find Full Text PDFIn order to replace the use of animals in toxicity testing, there is a need to predict in vivo toxic doses from concentrations that cause toxicological effects in relevant in vitro systems. The Virtual Cell Based Assay (VCBA) estimates time-dependent concentration of a test chemical in the cell and cell culture for a given in vitro system. The concentrations in the different compartments of the cell and test system are derived from ordinary differential equations, physicochemical parameters of the test chemical and properties of the cell line.
View Article and Find Full Text PDFThis chapter focuses on practical aspects of conducting prospective in vitro validation studies, and in particular, by laboratories that are members of the European Union Network of Laboratories for the Validation of Alternative Methods (EU-NETVAL) that is coordinated by the EU Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM). Prospective validation studies involving EU-NETVAL, comprising a multi-study trial involving several laboratories or "test facilities", typically consist of two main steps: (1) the design of the validation study by EURL ECVAM and (2) the execution of the multi-study trial by a number of qualified laboratories within EU-NETVAL, coordinated and supported by EURL ECVAM. The approach adopted in the conduct of these validation studies adheres to the principles described in the OECD Guidance Document on the Validation and International Acceptance of new or updated test methods for Hazard Assessment No.
View Article and Find Full Text PDFThere is a need to interpret in vitro concentration-viability data in terms of the actual concentration that the cells are exposed to, rather than the nominal concentration applied to the test system. We have developed a process-based model to simulate the kinetics and dynamics of a chemical compound in cell-based in vitro assays. In the present paper we describe the mathematical equations governing this model as well as the parameters that are needed to run the model.
View Article and Find Full Text PDFStatistical-based and expert rule-based models built using public domain mutagenicity knowledge and data are routinely used for computational (Q)SAR assessments of pharmaceutical impurities in line with the approach recommended in the ICH M7 guideline. Knowledge from proprietary corporate mutagenicity databases could be used to increase the predictive performance for selected chemical classes as well as expand the applicability domain of these (Q)SAR models. This paper outlines a mechanism for sharing knowledge without the release of proprietary data.
View Article and Find Full Text PDFAims: To investigate the correlation between O(6)-methylguanine-DNA-methyltransferase (MGMT) promoter methylation and benefit from temozolomide in patients with recurrent high-grade glioma.
Patients And Methods: A real-time, quantitative, methylation-specific PCR assay was performed on archival tissue blocks from patients treated with temozolomide at the first recurrence.
Results: A subgroup of 38 patients who were chemotherapy-naive at recurrence was analysed (22 glioblastoma, 12 anaplastic astrocytoma [AA] and 4 anaplastic oligoastrocytoma [AOA]); none had 1p/19q loss.
The protein kinase Sch9 is proposed to be a downstream effector of TORC1 that is required for activation of ribosome biogenesis and repression of entry into G(0). However, Sch9 apparently functions antagonistically to TORC1, when considering the induction of several stress defence genes that are normally repressed by TORC1. To further investigate the relationship between Sch9 and TORC1, we compared the rapamycin-induced transcriptional responses in an sch9Delta mutant and the isogenic wild type.
View Article and Find Full Text PDFPurpose: This multicentric, randomized, two-stage phase II trial evaluated three simplified weekly infusional regimens of fluorouracil (FU) or FU plus folinic acid (FA) and cisplatin (Cis) with the aim to select a regimen for future phase III trials.
Patients And Methods: A total of 145 patients with advanced gastric cancer where randomly assigned to weekly FU 3,000 mg/m2/24 hours (HD-FU), FU 2,600 mg/m2/24 hours plus dl-FA 500 mg/m2 or l-FA 250 mg/m2 (HD-FU/FA), or FU 2000 mg/m2/24 hours plus FA plus biweekly Cis 50 mg/m2, each administered for 6 weeks with a 1-week rest. The primary end point was the response rate.
The aim of this assessor-blinded trial was to compare the immunogenicity and reactogenicity of a candidate diphtheria, tetanus toxoids and acellular pertussis vaccine with reduced antigen content for diphtheria and pertussis (dTpa) with a licensed reduced adult-type diphtheria-tetanus vaccine Td (reduced diphtheria content) and with an experimental candidate monovalent acellular pertussis vaccine with reduced antigen content (pa). The dTpa and pa vaccines had identical pertussis antigen content. A total of 299 healthy adults (> or =18 years, mean age: 30.
View Article and Find Full Text PDFAnticancer Drugs
February 1995
KW-2149 is a new, semisynthetic, C-7-N-substituted, mitomycin C (MMC) analog showing equal or superior antitumor activity in both in vitro and in vivo assays. The preclinical activity profile combined with the hematological toxicity data in rodents and the water solubility of the compound compare favorably with MMC. The aim of this phase I study was to determine the toxicity profile and the optimal dosage of KW-2149.
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