Apoptosis is a term used to describe certain forms of physiological cell death that occur during embryogenesis, differentiation, and normal cell turnover. Previous reports concerning the effects of calcium ionophores on rodent thymocytes and the pore-forming proteins perforin and staphylococcal alpha-toxin on murine tumor cells led to the suggestion that simply raising intracellular calcium causes apoptotic cell death. This hypothesis was tested using two ionophores, A23187 and valinomycin, and two pore-forming agents, melittin and staphylococcal alpha-toxin, on four murine tumor cell lines. Although treatment with these agents could raise intracellular calcium, and in some instances cause DNA fragmentation, only valinomycin caused apoptosis. In contrast to previous reports, our results suggest that raising intracellular calcium and inducing internucleosomal DNA fragmentation is not sufficient to elicit apoptotic cell death in all cell types.

Avian scavengers, such as American crows (Corvus brachyrhynchos), have potential to translocate infectious agents (prions) of transmissible spongiform encephalopathy (TSE) diseases including chronic wasting disease, scrapie, and bovine spongiform encephalopathy. We inoculated mice with fecal extracts obtained from 20 American crows that were force-fed material infected with RML-strain scrapie prions. These mice all evinced severe neurological dysfunction 196–231 d postinoculation ( = 198; 95% CI: 210–216) and tested positive for prion disease. Our results suggest a large proportion of crows that consume prion-positive tissue are capable of passing infectious prions in their feces ( = 1.0; 95% CI: 0.8–1.0). Therefore, this common, migratory North American scavenger could play a role in the geographic spread of TSE diseases.

Though Freund's complete adjuvant effectively increases immune response to vaccines in various species, its potentially severe inflammatory effects have led many animal researchers to seek alternative immunological adjuvants. In a study of New Zealand white rabbits, the authors compared the immune and adverse effects of Freund's complete adjuvant with the effects of two formulations of AdjuVac, an immunological adjuvant previously developed by their group. All three adjuvants improved humoral immune response but also caused inflammation. Inflammatory reactions caused by AdjuVac, however, tended to be less severe than those caused by Freund's complete adjuvant.

Toxoplasma gondii infection, like malaria, is sensitive to inhibition by artemisinin (ART). Mechanisms of action for ART in malaria treatment have been proposed, but little is known about its effects in T. gondii infection. To better understand its inhibitory effects on T. gondii, mutants resistant to ART were selected by progressive culture in permissive levels of the drug. Five clonal isolates were established and characterized. The isolates were approximately 65-fold less sensitive to ART than is the parental RH and showed cross-resistance to the ART derivatives dihydroartemisinin and artemether. In addition to ART resistance, 1 clone (C9) formed morphologically unusual parasitophorous vacuoles and another (A2) was avirulent for mice and protected mice from challenge with the wild type. These clonal T. gondii mutant isolates will be useful for the study of not only the mechanism of action of ART but also parasite vacuole biology and virulence factors.