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DNA Replication, second edition, a classic of modernscience, is now back in print in a paperback edition. Kornberg and Baker'sinsightful coverage of DNA replication and related cellular processes have madethis the standard reference in the field.

The critically acclaimed laboratory standard for more than forty years, Methods in Enzymology is one of the most highly respected publications in the field of biochemistry. Since 1955, each volume has been eagerly awaited, frequently consulted, and praised by researchers and reviewers alike. More than 270 volumes have been published (all of them still in print) and much of the material is relevant even today--truly an essential publication for researchers in all fields of life sciences. Key Features* Expression, purification, and characterization* Activity assays* Kinetic and screening* Design and analysis of substrates and inhibitors* Molecular and structural characterizations.

These two volumes, entitled "Purine Metabolism in Man IV" con tain the papers presented at the Fourth International Symposium on Human Purine and Pyrimidine Metabolism", held in Maastricht (The Netherlands), June 1982. The proceedings of the three previous meet ings in Tel Aviv (Israel, 1973), Baden (Austria, 1976) and Madrid (Spain, 1979) were also published by Plenum Press. In the past few years interest in purine and pyrimidine metabo lism under normal and pathological conditions has been growing rapid ly. Apart from the more or less classical topics such as hyperuricae mia, clinical gout and urolithiasis, an increasing number of papers relating to other fields have been presented at successive meetings. Knowledge derived from the study of purine metabolism in relation to lymphocyte function, for instance, has opened up new possibilities for immunomodulation and leukaemia chemotherapy, with eventual conse quences for other types of cancer. At previous meetings there have been pointers implicating purine metabolism in relation to normal cardiac and skeletal muscle function. During the present meeting mych new data on both issues have been re ported which indicate clear differences in the pathways of ATP metabo lism. The widening of the field of interest is also illustrated by the recent work on infectious disease: exploitation of the differences in purine metabolic pathways in certain parasites compared with those in human cells has resulted in new rationales for therapy being devel oped.

DNA replication in eukaryotes is an important field, particular ly because of its direct impact on the study of cancer. The under standing of molecular mechanisms of replication and their regulation should allow a better comprehension of the alterations that lead to the proliferation of tumor cells and to error-prone repair in cells exposed to radiation or chemical carcinogens. During the last several years, many enzymes and proteins which participate in replication of DNA in eukaryotic cells have been identified, isolated and characterized. New concepts in chromatin structure have refocused attention on the study of replication of DNA complexed with his tones and non-histone chromosomal proteins. However, progress has been noticeably slower than for prokaryotes, essentially because of the difficulty in genetic analysis of eukaryo tic DNA replication. In June 1980, a workshop was organized in Cargese, Corsica (France) to facilitate exchanges of information between workers spe cializing in prokaryotes and those specializing in eukaryotes, and to allow discussion of new experimental approaches. With this in mind, special interest has been taken in the origin and termination of chromosome cycles and how they are controlled.

"In modern-day medicine, the use of intravascular catheters has become unavoidable. In the United States, hospitals and clinics purchase more than 150 million intravascular devices each year of which more than 5 million are central venous catheters (CVC). "