As with the previous four EeeLS Seminars, the contributions to the fifth Seminar in Siena have been collected together for the benefit both of those who were fortunate to be present and those unable to come. This Seminar differed from the others in having a more purely scien- tific content; however the contributors also considered the possible need for standardization in the future. The speakers were chosen for their acknowledged expertise in the specific topics. The papers are now presented in the order in which they were given with editorial change only to give consistency of style of presentation. It follows that each paper can stand alone at the expense of a minimum of repetition. Because the topics are in rapidly developing fields of high technology, speed of publication was essential; for help with this, EeeLS thanks the contributors. vii List of Contributors W. H. W. ALBERT D. M. BAND Boehringer Mannheim GMBH Sherrington School of Physiology Biochemical Research Centre St Thomas Hospital Medical School 0-8132 T utzing Lambeth Palace Road Federal Republic of Germany London SE1 7EH United Kingdom D. AMMAN Department of Organic Chemistry M. L. BIANCHI BANDINELLI Swiss Federal Institute of Institute of Microbiology Technology (ETH) University of Siena UniversiUitstr. 16 Via Laterina 8 CH-8092 Zurich 53100 Siena Switzerland Italy P. ANKER P. O. BRUNNER Department of Organic Chemistry Medical Instruments Swiss Federal Institute of Spectrospin AG Technology (ETH) Industriestrasse 26 Universitatstr. 16 CH-8117 Fallanden CH-8092 Zurich Switzerland Switzerland D. ARMELLINI M.