Walter L. Hughes

A PHYSICOCHEMICAL RATIONALE FOR THE BIOLOGICAL ACTIVITY OF MERCURY AND ITS COMPOUNDS

An equation is presented which describes the affinity of methylmercury for biological substances. Relative affinities for various biological substances may then be obtained by comparing the equilibrium constants for the reaction. The distribution of methylmercury in the body is discussed, and the preferential accumulation of mercury salts in kidney, liver, and spleen is discussed. The data available on the distribution of mercury in human tissues indicate that pathological effects are the result of real concentrations of mercury in the affected organs. In the case of the brain, which has been considered extremely sensitive to mercury, mental impairment has been found at levels of greater than 1 ppm. 17 references, 2 tables.

THE CHEMISTRY OF IODINATION

Reactions involved in the iodination of proteins are discussed. Procedures for the preparation of I/sup 131/-labeled proteins are described. (C.H.)

X-rays Affect the Incorporation of 5-Iododeoxyuridine into Deoxyribonucleic Acid

When labeled with iodine-131, 5-iododeoxyuridine, an analogue of thymidine, is useful in estimating the effect of x-radiation on deoxyribonucleic acid metabolism. Although this compound is readily incorporated into deoxyribonucleic acid in the absence of ionizing radiation, we find that whole-body exposure to as little as 10 r will significantly inhibit its incorporation.

Nucleic acid metabolism and the lethal effect of radiation on cultured human cells (HeLa).

Results are presented on studies that show that the defect (if any) induced in DNA metabolism by radiation exposure of cells has little or nothing to do with the effects causing mitotic delay and death. Moreover, irradiation does not appear to have any effect on the rate of entry of cells into DNA synthesis and ribonucleic acid metabolism is almost completely unaffected by highly lethal doses of x radiation. (auth)

Autoradiography with Tritium

In autoradiography, a photographic emulsion is placed in contact with a specimen containing radioactivity and stored in the dark. The radiation, passing through the emulsion, sensitizes silver bromide granules so that they can be reduced to metallic silver by a photographic developer. One then sees a pattern of silver grains lying above the specimen. (The technique [1] employed in the present studies made use of stripping film which was floated over a histological preparation. In some cases Feulgen staining was performed before autoradiography; in other cases the specimen was stained through the emulsion after photographic development.)

A simple fast micromethod for measuring enzyme activities which release tritium as tritium water

The entire procedure is carried out in a counting vial by mixing the reagents as a 20- to 30-microliters drop in the cap of a counting vial, incubating, quenching the reaction, and then distilling the tritium water produced into the chilled vial, in which it is assayed after the addition of scintillation solvent and a clean cap. The application of this technique to the analysis of serum transaminases is described.