Mechanistic approaches and the development of alternative toxicity test methods.

A mechanism can be defined as an explanation of an observed phenomenon that explains the processes underlying the phenomenon in terms of events at lower levels of organization. A prerequisite for new, more mechanistic, approaches, which would use in vitro systems rather than conventional animal analogy models, is a strengthening of the underlying scientific basis of toxicity testing. This will require greater recognition of the differences between fidelity and discrimination models and between analogy and correlation models. The development of high-fidelity, high-discrimination tests with a sound mechanistic basis will also require greater appreciation of the interdependence of all the components of test systems and the development of new alternative (i.e., nonanimal) testing strategies that can provide the specific knowledge needed for making relevant and reliable predictions about the potential effects of chemicals and products in human beings. The optimal use of this new knowledge will require fundamental changes to current practices in risk assessment

The optimal selection of turbine-generators for tidal power projects and the optimization of their operation

This thesis describes the development of a suite of computerprograms designed to evaluate the optimum operating strategyfor turbine-generators installed in a proposed tidal powerbarrage. The computer models are of the single-tide type buthave been extended to incorporate detailed models of theturbine performance characteristics and operating constraints.The computer programs have been extensively used for studies ofthe Severn and Mersey barrage proposals in the UK, for one ofthe proposed barrage schemes in the Bay of Fundy, Canada andfor the now-operating scheme at Annapolis Royal, Canada.One of the most important features of these programs is theirability to simulate, using appropriate characteristics, all thedifferent turbine types suitable for tidal power generation.Results are presented of particular studies showing in eachcase the conclusions reached

Ethical Aspects of Animal Experimentation

If inquiries are made of people regarding their attitudes towards animal experimentation, there will no doubt be various answers corresponding to the different ethical attitudes today. Three principle points of view are imaginable. The two extremes are: an unrestricted support of all animal experiments; and a radical rejection of any such experiment. These two positions, in all likelihood, are taken by only a minority of the population. The majority will approve of animal experimentation in principle, however, only insofar as it is really necessary to preserve human life. So, the point of controversy arises from the question: When is an animal experiment necessary and indispensable

Systematic Reviews of Animal Experiments Demonstrate Poor Human Clinical and Toxicological Utility

The assumption that animal models are reasonably predictive of human outcomes provides the basis for their widespread use in toxicity testing and in biomedical research aimed at developing cures for human diseases. To investigate the validity of this assumption, the comprehensive Scopus biomedical bibliographic databases were searched for published systematic reviews of the human clinical or toxicological utility of animal experiments. In 20 reviews in which clinical utility was examined, the authors concluded that animal models were either significantly useful in contributing to the development of clinical interventions, or were substantially consistent with clinical outcomes, in only two cases, one of which was contentious. These included reviews of the clinical utility of experiments expected by ethics committees to lead to medical advances, of highly-cited experiments published in major journals, and of chimpanzee experiments — those involving the species considered most likely to be predictive of human outcomes. Seven additional reviews failed to clearly demonstrate utility in predicting human toxicological outcomes, such as carcinogenicity and teratogenicity. Consequently, animal data may not generally be assumed to be substantially useful for these purposes. Possible causes include interspecies differences, the distortion of outcomes arising from experimental environments and protocols, and the poor methodological quality of many animal experiments, which was evident in at least 11 reviews. No reviews existed in which the majority of animal experiments were of good methodological quality. Whilst the effects of some of these problems might be minimised with concerted effort (given their widespread prevalence), the limitations resulting from interspecies differences are likely to be technically and theoretically impossible to overcome. Non-animal models are generally required to pass formal scientific validation prior to their regulatory acceptance. In contrast, animal models are simply assumed to be predictive of human outcomes. These results demonstrate the invalidity of such assumptions. The consistent application of formal validation studies to all test models is clearly warranted, regardless of their animal, non-animal, historical, contemporary or possible future status. Likely benefits would include, the greater selection of models truly predictive of human outcomes, increased safety of people exposed to chemicals that have passed toxicity tests, increased efficiency during the development of human pharmaceuticals and other therapeutic interventions, and decreased wastage of animal, personnel and financial resources. The poor human clinical and toxicological utility of most animal models for which data exists, in conjunction with their generally substantial animal welfare and economic costs, justify a ban on animal models lacking scientific data clearly establishing their human predictivity or utility

Methods for reliability and uncertainty assessment and for applicability evaluations of classification- and regression-based QSARs

This article provides an overview of methods for reliability assessment of quantitative structure–activity relationship (QSAR) models in the context of regulatory acceptance of human health and environmental QSARs. Useful diagnostic tools and data analytical approaches are highlighted and exemplified. Particular emphasis is given to the question of how to define the applicability borders of a QSAR and how to estimate parameter and prediction uncertainty. The article ends with a discussion regarding QSAR acceptability criteria. This discussion contains a list of recommended acceptability criteria, and we give reference values for important QSAR performance statistics. Finally, we emphasize that rigorous and independent validation of QSARs is an essential step toward their regulatory acceptance and implementation. Key words: QSAR acceptability criteria, QSAR applicability domain, QSAR reliability, QSAR uncertainty estimation, QSAR validation

Challenging the 'New Professionalism': from managerialism to pedagogy?

In recent years there have been changes made to the conceptualisation of continuing professional development for teachers in both the Scottish and English systems of education. These changes have been instigated by successive UK governments (and more recently, by the Scottish Executive), together with the General teaching Council for Scotland (GTCS) and the General Teaching Council for England (GTCE). This paper argues that these changes have not provided a clear rationale for CPD, but instead have introduced tensions between the concept of teacher education and that of training. The need for a less confused understanding of CPD and its purposes is underlined, as is the need for school based approaches to continuing teacher education. Arguably, teacher education must move from technicist emphases to a model which integrates the social processes of change within society and schools with the individual development and empowerment of teachers