ABSTRACT
From the early days of medical science, animal models of human disease have been indispensable to the understanding of the etiologies and progression of diseases, and for the development of therapeutic strategies (Melby, 1987; Kawamata and Melby, 1987; Loew, 1991). Recent advances in cell and molecular biology, and in computer technology, have facilitated the development of cell culture models, mathematical models, and computer simulations, which will undoubtedly be used to replace expensive animal experimentation where possible. However, in spite of these developments and the current societal desire to supplant research animals with cell culture models or computer simulations, animal models continue to remain a necessary and vital component of drug development efforts into the foreseeable future (Trull, 1987; Melby, 1987; Loew, 1991). Currently, progress in the development of treatments for many diseases of considerable societal impact, such as AIDS and Alzheimer's disease, suffers owing to lack of appropriate animal models (Palca, 1992; Joachim and Selkoe, 1992). Animal models are vital in delineating disease mechanisms, in defining intervention targets, in drug screening, and in preclinical drug evaluation.
