We used a molecular method and demonstrated that treatment of the chronic human Trypanosoma cruzi infections with nitroderivatives did not lead to parasitological cure. Seventeen treated and 17 untreated chronic Chagas' disease patients, with at least two out of three positive serologic assays for the infection, and 17 control subjects formed the study groups. PCR assays with nested sets of T. cruzi DNA primers monitored the efficacy of treatment. The amplification products were hybridized to their complementary internal sequences. Untreated and treated Chagas' disease patients yielded PCR amplification products with T. cruzi nuclear DNA primers. Competitive PCR was conducted to determine the quantity of parasites in the blood and revealed < 1 to 75 T. cruzi/ml in untreated (means 25.83+/-26.32) and < 1 to 36 T. cruzi/ml in treated (means 6.45+/-9.28) Chagas' disease patients. The difference between the means was not statistically significant. These findings reveal a need for precise definition of the role of treatment of chronic Chagas' disease patients with nitrofuran and nitroimidazole compounds.
Full-length RNA transcribed from the human LINE-1 (Li) element Li Homo sapiens (LlHs) has a 900-nt, G+C-rich, 5'-untranslated region (UTR). The 5' UTR is followed by two long open reading frames, ORF1 and ORF2, which are separated from each other by an inter-ORF region of 33 nt that includes two or three in-frame stop codons. We examine here the mechanism(s) by which the translation of LlHs ORF1 and ORF2 is initiated. A stable hairpin structure (AG =-74.8 kcal/mol), inserted at nt 661 of the 5' UTR, caused a 3-to 8-fold decrease in the in vitro and in vivo translation ofeither a lacZ reporter gene for ORF1 or the ORF1 polypeptide product, p40, but translation of a lacZ reporter gene in ORF2 was increased. The results are compatible with a model for ORF1 translation initiation in which the majority of ribosomes scan from a point 5' of nt 661 but suggest that ORF2 is not translated by attached ribosomes that reinitiate after the termination of ORF1 translation. Our data are compatible with a model whereby the translation of LlHs ORF2 is initiated internally. The human LINE-1 (Li) element (Li Homo sapiens; LiHs) is the only known transposable element that is endogenous to the human genome. The structural features of LlHs (sche-matically presented in Fig.
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