This book contains the scientific contributions presented at an International Symposium held in Sorrento, Italy, in June 1988 under the auspices of the University of Naples, the Italian Society of Biochemistry, and the National Research Council. The modern history of polyamines dates back to 1958 when the Tabors and Rosenthal first described the outlines of their biological synthesis. From then on, and particularly in the last ten years, a veri table explosion of Literature, characterized by thousands of papers, has witnessed the interest of the scientific community toward these molecules. Perhaps the old statement that "polyamines are molecules in search of a function" is no longer true today. A large number of effects exerted by these simple molecules are well known, and in many cases the mechanisms underlying these effects have been elucidated. The first section of the volume is entirely devoted to the enzymology and molecular biology of ornithine decarboxylase. Since its discovery by Gale more than forty years ago, this can be considered among the most widely studied enzymes in biology, and one of the most complex models in enzyme regulation. The mechanism of control of the enzyme activity at the transcriptional, post-transcriptional and post-translational levels, as well as the fine regulation by antizyme, are discussed in detail. The second group of contributions deals wi th AdoMet decarboxylase, propylamine transferase, polyamine oxidase and the other enzymes related to polyamine interconversion and regeneration.