Silver amplification of mercury sulfide and selenide: a histochemical method for light and electron microscopic localization of mercury in tissue.

A method for light and electron microscopic demonstration of mercury sulfides and mercury selenides in mammalian tissue is presented. Silver ions adhering to the surface of submicroscopic traces of mercury sulfides or selenides in the tissue are reduced to metallic silver by hydroquinone. Physical development thereupon renders deposits of mercury sulfides or mercury selenide visible as spheres of solid silver. Examples of localization of mercury in the central nervous system and various organs from animals exposed to mercury chloride or methyl mercury chloride with or without additional sodium selenide treatment are presented. Selenium treatment results in a considerable increase in the amount of mercury that can be made visible by silver amplification. After mercury chloride treatment, most of the mercury is localized in lysosomes and is only rarely seen in secretory granules. After simultaneous selenium treatment, mercury is also found in nuclei of proximal tubule cells in the kidney and in macrophages. The "sulfide-osmium" method for ultrastructural localization of mercury suggested by Silberberg, Lawrence, and Leider (Arch Environ Health 19:7, 1969) and the light microscopic method using a photographic emulsion suggested by Umeda, Saito, and Saito (Jpn J Exp Med 39:17, 1969) have been experimentally analyzed and commented on.

Simplified determination of urinary delta-aminolevulinic acid in a wide range of concentrations.

We describe a simple method for measuring delta-aminole-vulinic acid in urine without the need for the seldom-used but time-consuming internal-standard addition step. It combines the analytical procedure described by Tomokuni and Ogata [Clin. Chem. 18, 1534 (1972)] and a correction based on urine density to obtain, more rapidly and less expensively, results as accurate as those given by the Davis and Andelman [Arch. Environ. Health 15, 53 (1967)] chromatographic method.