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JAMA. 1948;136(7):473. doi:10.1001/jama.1948.02890240039010.
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A promising new method of immunologic research has been introduced by Libby and Madison1 of the Stamford Research Laboratories, American Cyanamid Company, in their study of the topographic distribution of a radioactive virus after intravenous injection into mice. Radioactive tobacco mosaic virus (TMV) was prepared by the method developed by Born2 and Stanley.3 Seedling tobacco plants 2 to 3 inches high were inoculated with tobacco mosaic virus and then placed in individual brown glass bottles, each of which contained 120 cc. of nutrient solution. To each bottle there was then added 18 mg. of sodium biphosphate (Na2HP*O4) containing approximately 278 microcuries of radioactive phosphorus (P32). The level of radioactivity was maintained for thirty days at between 1 and 3 microcuries per cubic centimeter by weekly additions of the radioactive sodium biphosphate or by complete changes in the nutrient solution. After the inoculated


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