Listeriolysin is a virulence factor that appears to be necessary for the intracellular survival of Listeria monocytogenes. As shown in this investigation, listeriolysin is produced in only small amounts by clinical isolates of L. monocytogenes belonging to the serogroup 1/2a, but its synthesis can be induced by heat shock and to a lesser extent by oxidative stress. In addition to about 15 heat shock proteins that appear to be common to L. monocytogenes and Listeria species that are nonpathogenic for humans, at least five heat shock proteins are specifically coinduced with listeriolysin in all L. monocytogenes strains under heat shock conditions but not in the other Listeria species. One type of L. monocytogenes mutant blocked in the expression of listeriolysin failed to synthesize several of these specific heat shock proteins.

The purpose of this study was to determine the copper deposition and localization during the evolution of two murine mammary adenocarcinomas. In the normal tissue, the copper was located within the cytoplasm, whereas it was intra- and perinuclear in the tumors. The more angiogenic and metastatic tumor showed the higher percentage of copper-positive cells. In the tumor, copper deposits correlated well with its angiogenic and metastatic ability, but additional factors would be required for the process to be induced.

The taeniid tapeworm Echinococcus granulosus is the causative agent of echinococcal disease, a major zoonosis with worldwide distribution. Several efforts to establish an in vitro model of E. granulosus have been undertaken; however, many of them have been designed for Echinococcus multilocularis. In the present study, we have described and characterized a stable cell line obtained from E. granulosus bovine protoscoleces maintained 3 yr in vitro. Growth characterization, morphology by light, fluorescent and electronic microscopy, and karyotyping were carried out. Cell culture origin was confirmed by immunofluorescent detection of AgB4 antigen and by PCR for the mitochondrial cytochrome c-oxidase subunit 1 (DCO1) gene. Cells seeded in agarose biphasic culture resembled a cystic structure, similar to the one formed in secondary hosts. This cell line could be a useful tool to research equinococcal behavior, allowing additional physiological and pharmacological studies, such as the effect of growth factors, nutrients, and antiparasitic drugs on cell viability and growth and on cyst formation.

S U M M A R YCyclophilins are target molecules for cyclosporin A (CsA), an immunosuppressive antimicrobial drug. We have previously reported the in vitro anti-Trypanosoma cruzi activity of H-7-94 and F-7-62 non-immunosuppressive CsA analogues. In this work, we continue the study of the parasiticidal effect of H-7-94 and F-7-62 CsA analogues in vitro and in vivo and we analyse 3 new CsA derivatives : MeIle-4-CsA (NIM 811), MeVal-4-CsA (MeVal-4) and D-MeAla-3-EtVal-4-CsA, (EtVal-4). The most efficient anti-T. cruzi effect was observed with H-7-94, F-7-62 and MeVal-4 CsA analogues evidenced as inhibition of epimastigote proliferation, trypomastigote penetration, intracellular amastigote development and in vivo T. cruzi infection. This trypanocidal activity could be due to inhibition of the peptidyl prolyl cis-trans isomerase activity on the T. cruzi recombinant cyclophilins tested. Furthermore, CsA and F-7-62 derivative inhibited the efflux of rhodamine 123 from T. cruzi epimastigotes, suggesting an interference with a P-glycoprotein activity. Moreover, H-7-94 and F-7-62 CsA analogues were not toxic as shown by cell viability and by aminopyrine-N-demethylase activity on mammalian cells. Our results show that H-7-94, F-7-62 and MeVal-4 CsA analogues expressed the highest inhibiting effects on T. cruzi, being promissory parasiticidal drugs worthy of further studies.