The effects of pyrantel tartrate on Sarcocystis neurona merozoite viability.

Sarcocystis neurona is the etiologic agent of equine protozoal myeloencephalitis, a neurologic disease of horses. The present study was designed to test the hypothesis that pyrantel tartrate can kill S. neurona merozoites growing in equine dermal cell culture. Sarcocystis neurona merozoites were exposed to a range of concentrations of pyrantel tartrate or sodium tartrate ranging from 0.001 to 0.01 M. Merozoites were then placed onto equine dermal cell cultures and incubated for 2 weeks to check for viability. At 1 and 2 weeks after inoculation, plaque counts were compared between treatments and, between treatments and controls. Merozoites exposed to concentrations of pyrantel tartrate higher than 0.0025 M (8.91 x 10(-4) g/ml) did not produce plaques in equine dermal cells, whereas those exposed to similar concentrations of the tartrate salt or medium alone produced significant numbers of plaques. These results demonstrate that pyrantel tartrate has activity against S. neurona merozoites in vitro and suggest that it may have activity against the sporozoite stage of the parasite found in the equine gut.

In situ separation of bacterial trapping and killing functions of the perfused liver.

CF-1 mice cleared and killed 80% of a 1.2 x 10(9) intravenous dose of Salmonella typhimurium after 30 min. The perfused mouse liver trapped 70% of a similar dose of S. typhimurium in a single pass, but in the perfusion model no significant killing of the trapped organisms was observed. The perfused rat liver also avidly trapped bacteria. Because of its larger size, we have been able to devise techniques to experimentally distinguish between the bacterial trapping and killing functions of this organ. When the liver was washed free of blood with sterile M-199, over 70 to 80% of a 10(6) to 10(10) dose of viable S. typhimurium was trapped after a single pass, but no significant bacterial killing was observed. When blood or plasma was added to the perfusion medium, over 50% of the trapped bacteria were killed in 15 to 30 min. Phase contrast and electron micrographs of perfused livers showed extensive extracellular trapping of bacteria in the sinusoids. Our data show that humoral factors are apparently not necessary for efficient trapping of live Salmonella by the perfused rat liver but are an absolute requirement for bacterial activity of the organ.