Selenium-silver interaction in mice

Activation of the immune system and systemic immune-complex deposits in Brown Norway rats with dental amalgam restorations

Dental amalgam restorations are a significant source of mercury exposure in the human population, but their potential to cause systemic health effects is highly disputed. We examined effects on the immune system by giving genetically mercury-susceptible Brown Norway (BN) rats and mercury-resistant Lewis (LE) rats silver amalgam restorations in 4 molars of the upper jaw, causing a body burden similar to that described in human amalgam-bearers (from 250 to 375 mg amalgam/kg body weight). BN rats with amalgam restorations, compared with control rats given composite resinous restorations, developed a rapid activation of the immune system, with a maximum 12-fold increase of the plasma IgE concentration after 3 wks (p < 0.001; Mann-Whitney's test). LE rats receiving amalgam restorations showed no significant increase of plasma IgE (p > 0.05). After 12 wks, BN rats with amalgam restorations showed significantly increased (p < 0.05) titers of immune-complex (IC) deposits in the renal glomeruli and in the vessel walls of internal organs. These rats also showed a significant (p < 0.05), from six- to 130-fold, increase in tissue mercury concentration in the concentration order kidney > spleen > cerebrum occipital lobe > cerebellum > liver > thymus, and the tissue silver concentration was significantly (p < 0.05) increased from three- to 11-fold. Amalgam-implanted BN rats showed a significant (p < 0.05) increase in copper concentration in the kidney and spleen, and in kidney selenium concentration. We conclude that dental amalgam restorations release substantial amounts of their elements, which accumulate in the organs and which, in genetically susceptible rats, give rise to activation of the immune system and systemic IC deposits.

Human generalized argyria: a submicroscopic and X-ray spectroscopic study

A 58-year-old man presented with a slate-gray discoloration of the skin. The patient had no medical complaint apart from the increasing cosmetic disability. He gave no drug history and denied professional exposure to chemical compounds. General medical examination was noncontributory; routine laboratory data were within the normal range. Light microscopy revealed the presence of numerous, small, pigmented particles at the dermal level. The submicroscopic investigation showed that the granules were deeply electron dense, had an irregular polycyclic contour, and varied in size between 100 and 600 nm. They were predominantly located in relation to the basal laminae of the epidermis and the cutaneous appendages, and in the dermal elastic fibers. In addition, the authors were able to document the presence of silver particles lying free in the cytoplasm of both epithelial cells of the secretory segment of eccrine sweat glands and mastcells, findings that have never been reported so far. X-ray spectroscopy documented that the electron-opaque particles contained silver, with some differences in the elemental composition of the granules, according to their location. These novel findings expand the knowledge of the various mechanisms of interaction of silver with the cellular and extracellular environment and allow some speculations about possible mechanisms of silver detoxification.