ATLA 26.2, March 1998

//ATLA 26.2, March 1998

News & Views

ATLA Staff Writer

UK Alternatives Funding Increased
Nominations Requested for 1998 Russell & Burch Award
Skin Irritation Alternatives on the Internet
Transgenic Mouse Brings Hope for Reduction
Calls for Research Proposals
FRAME on the Web
Amendment to ATLA 25.6
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2017-01-09T06:26:40+00:00 Tags: |

Reducing the Use of Laboratory Animals: Time for Strategic Actions and the Setting of Realistic Targets

Michael Balls

Opening a 30-minute Adjournment Debate in the House of Commons on 11 March 1998, Mr Norman Baker (Liberal Democrat MP for Lewes, and Hon. Treasurer of the newly re-formed All Party Parliamentary FRAME Group) asked whether the Government would set a target to reduce the number of animal experiments that will be carried out during the lifetime of the current Parliament (i.e. up to May 2002), and give an absolute guarantee that fewer experiments will be carried out each year at the end of it than at present.1 Unfortunately, when he asked the Home Office Minister for a yes or no answer at the end of the debate, the Deputy Speaker intervened to stop the discussion, in compliance with the rules of the House and since the time allowed had run out, so no categorical reply was received.
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2017-01-09T06:26:40+00:00 Tags: |

Alternative Methods for Skin Irritation Testing: the Current Status

Philip A. Botham, Lesley K. Earl, Julia H. Fentem, Roland Roguet and Johannes J.M. van de Sandt

The ECVAM Skin Irritation Task Force was established in November 1996, primarily to prepare a report on the current status of the development and validation of alternative tests for skin irritation and corrosion and, in particular, to identify any appropriate non-animal tests for predicting human skin irritation which were sufficiently well-developed to warrant ECVAM supporting their prevalidation/validation. The task force based its discussions around the proposed testing strategy for skin irritation/corrosion emanating from an OECD workshop held in January 1996. The following have been reviewed: a) structure-activity and structure-property relationships for skin corrosion and irritation; b) the use of pH and acid/alkaline reserve measurements in predicting skin corrosivity; c) in vitro tests for skin corrosion; d) in vitro tests for skin irritation (keratinocyte cultures, organ cultures, and reconstituted human skin models); and e) human patch tests for skin irritation. It was apparent that, although several promising candidate in vitro tests for skin irritation (for example, reconstituted human skin methods, and human and animal skin organ culture methods) were under development and evaluation, a test protocol, a preliminary prediction model and supporting data on different types of chemicals were only available for a method employing EpiDermTM. Thus, it is proposed that this EpiDerm test undergoes prevalidation during 1998. In addition, since it was felt preferable to be able to include other in vitro tests in such a prevalidation study, it is recommended that a “challenge” be set to anyone interested in taking part. This involves submitting data on ten test chemicals selected by the task force, obtained according to a standard protocol with a preliminary prediction model, for review by the task force by 31 May 1998.
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The Coumarin 7-Hydroxylation Microassay in Living Hepatic Cells in Culture

M. Teresa Donato, José V. Castell and Maria José Gómez-Lechón

Coumarin 7-hydroxylation was evaluated in hepatic cells from various species, cultured in 96-well plates. This microassay involved incubating living cultured cells with the substrate, followed by fluorimetric quantification of the product released into the culture supernatant, after hydrolysis of the conjugates of 7-hydroxycoumarin that were formed. Fluorescence was measured directly in the wells by using a microplate fluorescence reader. The major advantages of this technique are its simplicity and automation, the small number of cells required, the reduction in sample handling and assay time, and the possibility of performing repeated assays with the same cell monolayer, since no injury to cells is detectable during the assay. By using this microassay, it was shown that human hepatocytes hydroxylated coumarin at higher rates than did rabbit, dog or rat hepatocytes, and that no appreciable metabolic activity was observed in hepatoma cells (Hep G2 and FaO). In addition, methoxsalen was found to be a potent inhibitor of cytochrome P4502A6 activity in living human hepatocytes.
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In Vitro Studies on the Metabolism and Toxicity of Aflatoxin B1 in Primary Cultures of Black Catfish (Ictalurus melas)

Michela Ferraris, Erminio Marafante and Manjit Dosanjh

The capacity of a primary hepatocyte culture of black catfish (Ictalurus melas) to metabolise toxic compounds was evaluated by using aflatoxin B1 (AFB1) as a xenobiotic model. Hepatocytes were isolated by a two-step liver perfusion procedure and cultured in a serum-free medium on both porous membranes and 96-well microplates coated with Matrigel®. A viability of 95–98% was obtained. The ability to maintain cytochrome P450 activities was examined by measuring ethoxyresorufin-O-deethylase and pentoxyresorufin-O-depentylase activities, at various culture times. The cytotoxic effects of AFB1 on catfish hepatocytes were examined by using a neutral red uptake assay on 96-well microplates. The concentration causing 50% inhibition of uptake (IC50) value was 3μM. The AFB1 metabolites were analysed by HPLC with an ultraviolet diode array and fluorescent detectors. The results obtained show that catfish hepatocytes cultured on Matrigel retain their AFB1 metabolising activities for at least 6 days after seeding. This comparative study, using primary hepatocytes and isolated microsomes from black catfish, trout and mice, confirms that the observed marked differences in toxic response following exposure to AFB1 in these species are likely to be related to their various metabolising capacities.
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The Validation of Computational Prediction Techniques

Andrew P. Worth, Martin D. Barratt and J. Brian Houston

In a recent European Centre for the Validation of Alternative Methods (ECVAM) workshop report, various expert systems for
predicting chemical toxicity were reviewed, and recommendations were made regarding their development and validation (1). In this paper, we address the broader issue of validating computer-based approaches in general, rather than expert systems in particular. This is a topic which has received little direct attention in the validation literature, in spite of the continued development of such approaches.
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2017-01-09T06:26:41+00:00 Tags: |