Friday, June 29, 2012

Rosalyn Yalow and the Radioimmunoassay

The radioimmunoassay is a sensitive technique for measuring tiny amounts of biologically important molecules, such as the hormone insulin in the blood. The basic idea is to tag insulin with a radioisotope such as I-125, and mix it with antibodies for insulin. Then, add to this mix the patient’s blood. The insulin in the blood competes with the tagged insulin for binding to the antibodies. Next, remove the antibodies and their bound insulin, leaving just the free insulin in the supernatant. The radioactivity of the supernatant provides a way to determine the concentration of insulin in the blood.

Russ Hobbie and I describe the basics of a radioimmunoassay in Chapter 17 of the 4th edition of Intermediate Physics for Medicine and Biology.
Four kinds of radioactivity measurements have proven useful in medicine. The first involves no administration of a radioactive substance to the patient. Rather, a sample from the patient (usually blood) is mixed with a radioactive substance in the laboratory, and the resulting chemical compounds are separated and counted. This is the basis of various competitive binding assays, such as those for measuring thyroid hormone and the availability of iron-binding sites. The most common competitive binding technique is called radioimmunoassay. A wide range of proteins are measured in this manner.
The radioimmunoassay was developed by Rosalyn Yalow and Solomon Berson. Yalow received the Nobel Prize in Physiology or Medicine for this work in 1977 (Berson had died by then, and the Nobel committee never gives a prize posthumously). For readers of Intermediate Physics for Medicine and Biology, Yalow is interesting because she started out as a physics major, getting her bachelor’s degree in physics from Hunter College, part of the City University of New York (CUNY) system. In 1945 she obtained a PhD in nuclear physics from the University of Illinois at Urbana-Champaign. Building on this physics background, and collaborating with Berson, in the 1950s she developed the radioimmunoassay. Interestingly she and Berson refused to patent the method, wanting it to be freely available for use in medicine. Yalow died just over one year ago, at age 89.

You can learn more about Rosalyn Yalow and her inspiring life from her Nobel autobiography, her Physics Today obituary, her New York Times obituary, and the Jewish Woman’s Archive. For those who prefer a video, click here. I have not read Eugene Straus’s book Rosalyn Yalow: Nobel Laureate: Her Life and Work in Science, but I am putting it on my list of things to do.

Television interview with Rosalyn Yalow.

I often like to finish a blog entry about a noteworthy scientist with their own words. Below are the opening paragraphs of Yalow’s Nobel Prize Lecture.
To primitive man the sky was wonderful, mysterious and awesome but he could not even dream of what was within the golden disk or silver points of light so far beyond his reach. The telescope, the spectroscope, the radiotelescope—all the tools and paraphernalia of modern science have acted as detailed probes to enable man to discover, to analyze and hence better to understand the inner contents and fine structure of these celestial objects.

Man himself is a mysterious object and the tools to probe his physiologic nature and function have developed only slowly through the millenia. Becquerel, the Curies and the Joliot-Curies with their discovery of natural and artificial radioactivity and Hevesy, who pioneered in the application of radioisotopes to the study of chemical processes, were the scientific progenitors of my career. For the past 30 years I have been committed to the development and application of radioisotopic methodology to analyze the fine structure of biologic systems.

From 1950 until his untimely death in 1972, Dr. Solomon Berson was joined with me in this scientific adventure and together we gave birth to and nurtured through its infancy radioimmunoassay, a powerful tool for determination of virtually any substance of biologic interest. Would that he were here to share this moment.

1 comment:

  1. I love this:

    "Interestingly she and Berson refused to patent the method, wanting it to be freely available for use in medicine."