As was shown in the first two volumes of this series, great strides have been made in identifying many of the agents or classes of substances responsible for carcinogenesis and in delineating their interactions with the cell. Clearly, the aim of such studies is that, once identified, these agents can be eliminated from the environment. Yet, despite these advances and the elimination of some important carcinogenic agents, one major problem exists. It is a constant monitor of all oncologic study and diminishes the importance of every experiment and of every clinical observation. As we noted earlier, that problem is our inability to define the malignant cell. It is through studies of the fundamental biology of tumors that we seek this definition. A vast amount of information has been gathered which describes what this cell does and-to a lesser extent-how it does it. But the why evades us. We have been unable to define the malignant cell, save in broad terms by comparing it to its normal counterpart. The major problem appears to be that the malignant cell does so much. It is a chimera, mystifyingly composed of normal activities and structures, of phenotypic schizophrenia with embryonic, fetal, and adult charac teristics and, occasionally, a hint of an unclassifiable capacity unique to malignant cells.

Although glycoproteins and proteoglycans have been a subject of re search for many years, it is only during the last five or so years that they have aroused the interest of a very broad cross section of investigators in the biological sciences. The reason for this expanded interest in these molecules is simple: not only are glycoproteins and proteoglycans ubiq uitous, but many are molecules with well-defined and important biological functions. The list of molecules that fall into this category grows daily; interferon, immunoglobulins, certain hormones, many cell surface recep tors, and viral coat proteins are but a few examples. Thus, investigators with interests as diverse as viral replication. cell-cell interactions. poly isoprenoid synthesis, secretory processes, hormone responses, embryonic development, and immunology have become concerned with glycopro teins and proteoglycans. The objective of this book is to summarize the current state of knowledge on the biochemistry of these molecules. Coverage is by no means encyclopedic; rather the thrust is to emphasize the recent ad vances. The first chapter deals primarily with structural work on the oligosaccharide chains of glycoproteins, but it will be apparent in it and in the succeeding two chapters on biosynthesis that not only do structural studies aid biosynthetic investigations, but that studies on biosynthesis often playa major role in elucidation of structure.

The International Life Sciences Institute (ILSI) was creat ed to promote cooperative efforts toward solving critical health and safety questions involving foods, drugs, cosmet ics, chemicals, and other aspects of the environment. The Officers and Trustees believe that questions regarding health and safety are best resolved when government and industry rely on scientific investigations, analyses, and re views by independent experts. Further, the scientific aspects of an issue should be examined and discussed on an international basis, separate from the political concerns of individual companies. ILSI is pleased to sponsor this set of monographs on the pathology of laboratory animals. This project will be use ful in improving the scientific basis for the application of pathologic techniques to health and safety evaluation of substances in our environment. The world wide distribu tion of the authors, editors, and Editorial Board who are creating these monographs strengthens the expectation that international communication and cooperation will al so be strengthened.

Bioengineers need a thorough grounding in biocompatibility - the biological performance of materials. Until now, there were no publications suitable for a neophyte in the field; prior publications were either not comprehensive or focused on rather narrow interests. Drawing on the author's 35 years of experience as a teacher, researcher, and consult