Phosphorus-32 in the Phage Group: radioisotopes as historical tracers of molecular biology.

The recent historiography of molecular biology features key technologies, instruments and materials, which offer a different view of the field and its turning points than preceding intellectual and institutional histories. Radioisotopes, in this vein, became essential tools in postwar life science research, including molecular biology, and are here analyzed through their use in experiments on bacteriophage. Isotopes were especially well suited for studying the dynamics of chemical transformation over time, through metabolic pathways or life cycles. Scientists labeled phage with phosphorus-32 in order to trace the transfer of genetic material between parent and progeny in virus reproduction. Initial studies of this type did not resolve the mechanism of generational transfer but unexpectedly gave rise to a new style of molecular radiobiology based on the inactivation of phage by the radioactive decay of incorporated phosphorus-32. These 'suicide experiments', a preoccupation of phage researchers in the mid-1950s, reveal how molecular biologists interacted with the traditions and practices of radiation geneticists as well as those of biochemists as they were seeking to demarcate a new field. The routine use of radiolabels to visualize nucleic acids emerged as an enduring feature of molecular biological experimentation.

Polycythemia vera: a retrospective and reprise.

This article, by two of the late John H. Lawrence's fellows of the 1940s, traces the development of the knowledge of polycythemia vera from Vaquez, who wrote the first description of this disease, and Osler, who recognized it as "a new clinical entity," through John H. Lawrence and the use of 32P as a treatment for polycythemia vera, to the formation of French and Italian polycythemia study groups. In particular, the history of polycythemia vera after the Second World War, and its more recent history, can be traced through the development of an algorithm for evaluating an elevated hematocrit and the development of the first (O1) protocol of the Polycythemia Vera Study Group (PVSG), a randomized trial of the efficacy of 32P, chlorambucil, and phlebotomy for treating polycythemia vera. It was in 1948, only 9 years after the first use of 32P for treating polycythemia vera, that Byron Hall reported the occurrence of acute leukemia following this use of the isotope. This led to the formation of the PVSG. After completing enrollment of patients in the first protocol of the PVSG, an attempt to find a replacement for 32P as a myelosuppressive agent led to the testing of hydroxyurea as a putative non-leukemogenic drug for this purpose. However, the use of hydroxyurea for treating polycythemia vera is coming into question, as is the ability to maintain patients with phlebotomy alone. The PVSG as such no longer exists as an operational group; its files are maintained at the Mount Sinai School of Medicine in New York City. However, the French group created for the study of polycythemia vera has had a consensus conference, and the Italian group has developed a low-dose aspirin protocol for treating the disease.