Most serodiagnostic techniques have been evaluated for diagnosis of cystic hydatid disease caused by Echinococcus granulosus. Each, to varying degrees, has been shown to give false results, with considerable variation between laboratories. The comparative study was made concerning the sensitivity of the immunodiagnostic methods based on 58 sera from hydatid disease with different cyst locations. Latex agglutination, immunoelectrophoresis (IEP), and specific IgE, IgG enzyme‐linked immunosorbent assay (ELISA) tests were studied. Specific IgG ELISA AgB (antigen B‐rich fraction) was the most sensitive test (96.5%) and the least sensitive tests were specific IgE ELISA (24.1%) and IEP (25.8%). The low sensitivity of these two tests was due partly to the low reactivity detected in the sera of patients with lung hydatidosis. Initial laboratory studies showed purified antigens to be preferable to crude cyst fluid, regardless of the type of test used. For this reason, we evaluated the sensitivity and specificity of ELISA by using the purified antigen‐B‐rich fraction. In all, 117 sera were examined: 78 sera from patients with hydatidosis surgically confirmed, 15 sera from healthy control subjects, and 24 sera from patients with diseases other than hydatidosis. The method gave good results: 93.5% sensitivity, 89.7% specificity, and 92.3% diagnostic efficacy. J. Clin. Lab. Anal. 15:14–18, 2001. © 2001 Wiley‐Liss, Inc.

The unicellular organism Trypanosoma cruzi is an eukaryote whose cell cycle mainly occurs under darkness in the insect gut. The unique external phase corresponds to the metacyclic forms, the forms that are able to infect humans, which appear within the insect deyections. Thus, light may be a powerful stressor in this unicell. Epimastigote forms (the parasite forms that grow and transform to metacyclic forms in the insect gut) of Trypanosoma cruzi grow normally when cultured in a LD cycle of 0:24 hr, reaching exponential growth by the 7th day. A pulse of 2 hr of light (LD 2:22) was enough to block the growth of the epimastigotes, an effect that was correlated with the expression of heat-shock proteins during the first 120 min of light exposure. Thereafter, protein synthesis decreased. Light exposure of metacyclic forms also inhibits the parasitization ability. It is known that light regulates the production of melatonin in most animal species studied, including other unicells such as dinoflagellates. T. cruzi contains and synthesizes melatonin and, thus, light-mediated events on the parasite biological cycle could be mediated by light-induced changes in melatonin produced by this unicell. Epimastigotes cultured under continuous darkness produce melatonin over the 24 hr period in a biphasic manner. Coinciding with the melatonin peaks, there was high melatonin efflux from the parasite into the medium. Epimastigotes cultured for 7 days under a LD cycle of 2:22 hr showed a 55% reduction in melatonin content, although this reduction seems not to be related with the growth delay. In fact, incubation of epimastigotes with exogenous melatonin (1 pM) did not affect parasite growth, but significantly reduced their transformation into metacyclic forms by the 7-8th day of treatment. Thus, the light-dependent decrease in melatonin production by the unicell may be responsible, at least partially, for the light-induce parasitization inhibition. Moreover, melatonin production is highest in the metacyclic forms. These data support a link between light, melatonin production and parasitization ability of T. cruzi and suggest the participation of the indoleamine in its biological cycle.

The aim of this study was to evaluate the utility of nanoparticles of polyalkylcyanoacrylate as a targeted delivery system for nifurtimox against Trypanosoma cruzi, responsible for Chagas' disease. Ethylcyanoacrylate nanoparticles were prepared by an emulsion polymerization process and formulations containing different concentrations of nifurtimox, polyethylcyanoacrylates and surfactants were investigated and analysed for size and drug content. The nanoparticles obtained were less than 200 nm in size, as measured by electron microscopy and cytometry. The peak percentage of nifurtimox uptake into the nanoparticles was 33.4% for use of 500 microL polyethylcyanoacrylate, 200 microL surfactant (Tween 20) and 10 mg nifurtimox in 50 mL polymerization medium. The highest release of nifurtimox from the nanoparticles was 65.4% after 6-h incubation at pH 7.4. In-vitro studies using cultures of T. cruzi epimastigotes revealed considerably increased trypanocidal activity compared with a standard solution of nifurtimox. Studies of cell cultures previously infected with metacyclic forms of the parasite showed that only 2-h treatment with solutions of 0.001% of the nanoparticle suspension reduced parasitism by 87-94% both when the nanoparticles were loaded with nifurtimox and when unloaded. Electron-microscopic examination revealed processes of degeneration and lysis, suggesting apoptotic processes, in intracellular amastigotes and free amastigotes treated with the nanoparticles. It was demonstrated that unloaded nanoparticles, by mechanisms not completely elucidated, have trypanocide activity similar to that of a standard solution of nifurtimox. It is concluded that the nanoparticles loaded with nifurtimox constitutes a good carrier of the drug against T. cruzi. The loaded-nanoparticles significantly increase trypanocidal activity.

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The activities of 8 platinum drug complex salts were determined against Leishmania donovani promastigotes. The three most active salts were selected: [Pt^IVBr₆]H₂ (pentamidine); [Pt^IVBr₆]H₂ (stilbamidine), and [Pt^IVCl₆]H₂ (2-piperazinyl(1) ethyl amine), which induced growth-inhibition rates of more than 50% at 24 h of treatment and at the maximum dosage tested. The cytotoxicity assays on the macrophage cell line J-774 showed high cytotoxicity for the salt [Pt^IVBr₆]H₂ (stilbamidine) with a percentage of specific ⁵¹Cr release of 58.2% at 24 h of incubation and 100 µg/ml. Meanwhile, assays of the other compounds showed practically no cytotoxicity. The salt [Pt^IVBr₆]H₂ (pentamidine) notably inhibited the incorporation of ³H-thymidine in the treated parasites. The ultrastructural alterations observed in the flagellates treated with the salts [Pt^IVCl₆]H₂ (2-piperazinyl(1)ethyl amine) and [Pt^IVBr₆]H₂ (pentamidine) suggest that both act preferentially at the nuclear level and at the kinetoplast-mitochondrion complex. Both compounds showed a high in vivo activity in parasitized Wistar rats.