The war years had convinced Public Health Service (PHS) leaders that a clinical research facility larger than any then operating was vital to sustain the revolutionary advances in medicine and science that followed the development of penicillin in 1941.5 Successful antibiotic and chemical therapies for malaria, pneumonia, and tuberculosis encouraged popular expectations of cures for infectious diseases in general. By war’s end there was enormous public pressure through disease foundations, press and radio, and members of Congress to increase federal spending on hospitals and health care.6

Surgeon General Thomas Parran, committed to the New Deal vision of a universally accessible national health care system, used popular anxieties about disease cures to widen PHS mandates in disease control, hospital care, and scientific research.7 His deeper appreciation that clinical research would govern the development of scientific medicine came from his own clinical experience with arsenical therapies for syphilis in the early 1930s. Clinicians discovered then that patients reliably recovered only when an optimal dosage was determined through clinical trials conducted by different investigators with different patient groups, all following the same protocol. Since dozens or scores of research subjects were needed for each therapeutic evaluation, separately funded research wards in teaching hospitals had to be used to establish each drug’s viability.8

The arrival of sulfa drugs and penicillin in 1941 launched a revolution in clinical medicine, which tied laboratory science inextricably to the world of the clinician. Formerly bound only to diagnose and observe, practitioners of internal medicine were now free to treat patients with chronic diseases and to devise experimental therapies.9 Diagnostic technologies proliferated, disease processes were illuminated, and human biology became the essential proving ground for developmental biochemistry and physiology. As Parran saw it, the implications for NIH intramural research were foretold by the pattern of extramural grants the National Cancer Institute made in 1946. Cures would come, he told the House Appropriations Subcommittee, only after intensive basic research "directed toward fundamental problems of cellular life, the interaction of groups of cells and organ systems in this most complicated of all chemical structures, which is man himself".10

With the successful elucidation of the structure of DNA in 1953, it became clear that molecular biology would be the new frontier of scientific medicine.