GC-012F

From a panel of 34 artemisinin derivatives tested in vitro, artemisone, GC007 and GC012 were most efficacious at inhibiting Neospora caninum replication (IC50 values of 3-54nM), did not notably impair the invasiveness of tachyzoites and were non-toxic for human foreskin fibroblasts (HFFs). Transmission electron microscopy of drug-treated N. caninum-infected HFFs demonstrated severe alterations in the parasite cytoplasm, changes in the composition of the matrix of the parasitophorous vacuole (PV) and diminished integrity of the PV membrane. To exert parasiticidal activity, parasites had to be cultured continuously in the presence of 5μM artemisone or GC007 for 3 weeks. N. caninum tachyzoites readily adapted to a stepwise increase in concentrations (0.5-10μM) of GC012, but not to artemisone or GC007. Drugs induced the expression of elevated levels of NcBAG1 and NcSAG4 mRNA, but only NcBAG1 could be detected by immunofluorescence. Thus, artemisinin derivatives represent interesting leads that should be investigated further.

Monoclonal antibody GC12 was examined for its value in cytopathologic diagnosis. Its sensitivity and specificity in staining reactive mesothelial cells in serous effusions was determined using the indirect immuno alkaline phosphatase anti-alkaline phosphatase technique. Smears prepared from 78 serous effusions (15 benign, 54 malignant, 9 atypical) were immunostained with GC12 and five other monoclonal antibodies: KL1 directed against cytokeratins, D33 against desmin, E29 against epithelial membrane antigen, Calam 27 against epithelial surface antigen and NEO 723 reactive with carcinoembryonic antigen. GC12 reacted positively with 80 to 100% mesothelial cells from the 15 benign effusions. Carcinoma cells were negative in 87% of malignant cases. Ovarian carcinomas were specially stained among positive cases. One malignant mesothelioma was positive and one was unreactive with GC12. Moreover, the reactivity of atypical cells in 9 serous effusions with GC12 was helpful to characterize benign and malignant effusions: the immunophenotype GC12-, Desmine-, Calam 27+, EMA+, ACE+ allowed detection of carcinoma cells in 2 cases. It is concluded that GC12 is a good tool for distinguishing carcinoma cells from reactive mesothelial cells in serous effusions.