Radioactivity relative biological effectiveness

Although B12 can be assayed biologically in mice, chicks, and rats, especially with the use of radioactive cobalt, the microbiologic method of assay is preferred because it is economical and sensitive. One serious drawback of bacterial Bi2 assay procedures is the lack of specificity and sensitivity. The extreme sensitivity (1 X 10 12 g) and relative freedom of stimulation in blood, serum, and urine make protozoa the choice assay tools (B17, F3, H19). The most specific is O. malhamensis (B17, F3) Euglena is known to be stimulated by pseudo-B12 (F2). Serum and blood from normal subjects have a growth-promoting effect on Euglena (M12) above that seen with Ochromonas. The reason for such... 

The radioactive decay properties of the plutonium isotopes that appear in irradiated reactor fuel are listed in Table 9.14. All but Pu and Pu are alpha emitters. Because it penetrates matter only weakly, alpha radiation is stopped by the outer layer of dead skin and is not a hazard outside the body. However, plutonium is very effective biologically when deposited in or on living tissue, particularly if by inhalation or by contaminated injuries. Pu is a relatively short-lived (13.2-year... 

Several investigators have used neutron activation analysis (NAA) to determine the aluminium content of biological specimens both with and without some chemical processing. Instrumental neutron activation analysis involves the bombardment of a sample with neutrons and the measurement of the radioactivity induced by nuclear reactions. No chemical processing is required. Upon activation Al (100% isotopic abundance) forms the radioactive AI nuclide by a (n,y) reaction. There are a number of attractive features in this technique which include excellent sensitivity with relative independence from matrix effects and interferences. Also, there is relative freedom from contamination since the sample is analyzed directly with minimal handling. One major problem is the need to... 

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