This book is the outcome of an international conference, held at the Aviya Sonesta Hotel in Eilat, Israel, on March 24-27, 1985. This was the 30th in a series of the annual OHOLO Conferences, sponsored by the Israel Institute for Biological Research. Participants in this Conference consisted of scientists from four­ teen countries; represented a broad spectrum of research interests; and included a well-balanced representation from academia, clinical institutions and pharmaceutical industry. The book includes talks, poster sessions, and a comprehensive general discussion, all from the proceedings of this conference. In the interest of assuring a rapid publication of the novel infor­ mation reviewed, this book has been prepared in camera-ready format. We are cognizant of the fact that several typographical errors may exist in the text, and that there are variations in style and typeface of the var­ ious chapters. This, we felt, was a reasonable compromise for the sake of speed and efficient transmission of valuable scientific information. No­ body is perfect . •••• The success of the conference, and hence the quality of this book are attributable to the extensive efforts of a large number of extremely capable individuals. These include members of the Scientific Organizing Committee, and the Technical staff of the OHOLO Organization. Of course, the conference could not have succeeded without the high quality of the presentations, and the enthusiastic participation of the contributing scientists.