Navegando por Autor "Pinto, Artur da Silveira"
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Item Anti-trypanosomal activity of pentacyclic triterpenes isolated from Austroplenckia populnea (Celastraceae).(2002) Duarte, Lucienir Pains; Vieira Filho, Sidney Augusto; Silva, Grácia Divina de Fátima; Sousa, José Rego de; Pinto, Artur da SilveiraFour pentacyclic triterpenes isolated from Austroplenckia populnea and four compounds of known anti T. cruzi or anti-malarial activity were tested. Of those triterpenes tested 20_-hydroxy-tingenone showed high activity, epikatonic acid was less active, while populnilic and populninic acids were inactive against the trypanosome of the subgenus Schizotrypanum tested. Benzonidazole, nifurtimox, ketoconazole and primaquine presented a remarkable dose-dependent inhibitory effect reaching practically to a total growth inhibition of the parasite at the end of incubation time. The trypanosome tested appear to be a suitable model for preliminary screen for anti T. (S.) cruzi compounds.Item Cell surface analysis of trypanosomes of the subgenus Schizotrypanum isolate from bats.(1996) Pinto, Artur da Silveira; Teixeira, Luiz Fernando de Medeiros; Padron, Thais Cristina Baeta Soares Souto; Andrade, Arnaldo Feitosa Braga deTwo stocks (M5, M29) of trypanosomes of the subgenus Schizotrypanum were isolated from the bat Phylloslomus hastatus and analyzed for cell electrophoretic mobility (EPM) and lectin binding surface sites. Epimastigotes from the M5 and M29 stocks presented a mean EPM of around - 0.57 and -0.56 μm, s-1.V-1.cm, respectively. Differences in the agglutination profiles were detected between epimastigotes or trypomastigotes from the two parasite populations using lectins with specificity for D-GlcNAc, D-GalNAc, D-Gal and D-Man as probe. Major variation was observed between epimastigote forms. Additionally, the D-GlcNAc binding lectins WGA and BS II strongly interacted with the trypomastigote from both M5 and M29 stocks; this fact is evidence that these trypanosomes are distinct from Trypanosoma (Schizotrypanum) cruzi.Item Compared vectorial transmissibility of pure and mixed clonal genotypes of Trypanosoma cruzi in Triatoma infestans.(1998) Pinto, Artur da Silveira; Lana, Marta de; Bastrenta, Brigitte; Barnabé, Christian; Quesney, Virginie; Noel, Sébastien; Tibayrenc, MichelA total of 15 mixtures involving 9 di erent stocks attributed to the 19/20, 32 and 39 major clonal genotypes of Trypanosoma cruzi were used to infect third-instar nymphs of Triatoma infestans via an arti®- cial feeding device. Three biological parameters were considered: (1) the percentage of infected insects (%II), (2) the number of ¯agellates per insect (NFI), and (3) the percentage of trypomastigotes per insect (%DIF). Ge- netic characterization by both multilocus enzyme elec- trophoresis (MLEE) and random ampli®cation of polymorphic DNA (RAPD) indicated that in almost all cases (87%), mixtures remained present after completion of the whole cycle in the insect vector. Two lines of comparison were performed: (1) pure clonal genotypes versus corresponding mixed clonal genotypes and (2) the actual behavior of mixed clonal genotypes versus the expected behavior of the theoretical mixture (i.e. the arithmetic mean of the results observed for each of the two clonal genotypes taken separately). Statistical analyses of the variables were made di cult because of the presence of large standard deviations. Nevertheless, in several cases, mixtures di ered signi®cantly from pure clonal genotypes, and in one case the actual mixture di ered signi®cantly from the theoretical mixture. In some cases, interaction (either potentialization or re- ciprocal inhibition) could be suspected.Item Experimental Trypanosoma cruzi biclonal infection in Triatoma infestans : detection of distinct clonal genotypes using kinetoplast DNA probes.(2000) Pinto, Artur da Silveira; Lana, Marta de; Britto, Constança; Bastrenta, Brigitte; Tibayrenc, MichelMonitored biclonal densities of parasites were offered to third-stage larvae of Triatoma infestans via an arti®cial feeding device and 30 days later, the gut contents of the insects were processed for microscopic examination and polymerase chain reaction (PCR) detection of Trypanosoma cruzi kinetoplast DNA [kDNA]). A total of 15 mixtures involving nine different stocks attributed to the 19/20, 32 and 39 major clonal genotypes of Trypanosoma cruzi were used. The presence of each T. cruzi clonal genotype after completion of the cycle through the insects was investigated by hybridising the PCR ampli®cation products with genotype-speci®c minicircle kDNA probes. Sixty-®ve out of 90 examined insects (72.2%) were positive for parasites by microscopic examination and 85 (94.4%) were positive by PCR. The results show that almost half of the biclonal infections are not detectable after completion of the cycle, and that there are important differences in detection of such biclonal infections according to the clonal genotypes considered. Moreover, elimination of a clonal genotype by another is a frequent, but not constant, pattern in biclonal infections of T. infestans. The use of PCR and kDNA probes makes it possible to avoid the culture phase, which makes detection of mixed infections much easier in epidemiological surveys. Moreover, the fact that T. infestansdoes not transmit different T. cruzi clonal genotypes with the same ef®ciency has strong implications for the reliability of xenogiagnosis. q 2000 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.Item In vitro activity of 2-pyridinecarboxylic acid against trypanosomes of the subgenus Schizotrypanum isolated from the bat Phyllostomus hastatus.(2011) Corrêa, Paulo Roberto Ceridóreo; Pinto, Artur da Silveira; Silva, Grácia Divina de Fátima; Vieira Filho, Sidney Augusto; Duarte, Lucienir Pains; Ogatta, Sueli Fumie YamadaThe effect of 2-pyridinecarboxylic acid (picolinic acid) on trypanosomes of the subgenus Schizotrypanum isolated from the bat Phyllostomus hastatus was determined in this study. Picolinic acid, at 50 g mL-1, inhibited epimastigote growth by 99% after 12 days incubation. In addition, trypomastigote motility decreased by 50% after 6h and completely after 24h in the presence of 50 g mL-1 picolinic acid. The 50% cytotoxic concentration on HEp-2 cell line was 275 g mL-1 after 4 days incubation. Altogether, these results indicate higher toxicity against trypanosomes. The inhibitory effect of picolinic acid on epimastigote growth can be partially reversed by nicotinic acid and L tryptophan, suggesting a competitive inhibition. Furthermore, two anti-Trypanosoma (Schizotrypanum) cruzi drugs were also evaluated with regard to bat trypanosome growth. Benznidazole, at 50 g mL-1, inhibited epimastigote growth by 90% after 12 days incubation. Nifurtimox, at the same concentration, caused 96% growth inhibition after four days incubation. Corroborating a previous study, bat trypanosomes are a good model for screening new trypanocidal compounds. Moreover, they can be used to study many biological processes common to human pathogenic trypanosomatids.Item Trypanosoma cruzi : compared vectorial transmissibility of three major clonal genotypes by Triatoma infestans.(1998) Lana, Marta de; Pinto, Artur da Silveira; Barnabé, Christian; Quesney, Virginie; Noel, Sébastien; Tibayrenc, MichelItem Trypanosoma cruzi : infectivity of clonal genotype infections in acute and chronic phases in mice.(2000) Lana, Marta de; Pinto, Artur da Silveira; Bastrenta, Brigitte; Barnabé, Christian; Noel, Sébastien; Tibayrenc, Michel