Selenium has been shown to alter mercury metabolism and to decrease mercury toxicity. Parizek and his colleagues (1, 2) demonstrated that injection of selenite markedly diminished the toxicity of simultaneously administered mercuric chloride while paradoxically appearing to cause increased retention of the mercury. Ganther el al.( 3 ) reported that chronic methylmercury toxicity was decreased by feeding 0.5 ppm selenium. Recently Potter and Matrone (4) confirmed the findings of Ganther et al. using a dietary selenium concentration of 5 ppm and showed that this amount of selenium also decreases chronic inorganic mercury toxicity.Little is known of the mechanism by which selenium decreases mercury toxicity.

Amastigotes of Leishmania mexicana, L. mexicana amazonensis, L. brasiliensis, and L. enriettii were isolated from lesions in infected animals. Numbers of amastigotes recovered ranged from 1 X 10(7) to 7 X 10(8), depending on the strain of leishmania. Trypsinization disassociated the lesions and released the parasites. After 18 to 24 hr incubation at 37 C in tissue culture media with antibiotics, many of the intact host cells attached to the flask. Amastigotes were collected from the media in relatively pure preparations. Electron microscopy revealed no morphological alterations of the amastigotes and minimal contamination by membranes and cell fragments.

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