In an effort to unify the nomenclature of Trypanosoma cruzi, the causative agent of Chagas disease, an updated system was agreed upon at the Second Satellite Meeting. A consensus was reached that T. cruzi strains should be referred to by six discrete typing units (T. cruzi I-VI). The goal of a unified nomenclature is to improve communication within the scientific community involved in T. cruzi research. The justification and implications will be presented in a subsequent detailed report.

Lyophilized aqueous extract (LAE) from Lychnophora pinaster Mart (Asteraceae) aerial parts was evaluated in the search of possible biological activities. LAE exhibited trypanocidal activity (113.62 mg/mL), but could not inhibit 5-lipoxygenase in vitro (17% of inhibition). LAE chemical characterization by HPLC with UV-Diode Array Detector showed the presence of caffeic acid, isochlorogenic acid, vitexin, isovitexin and quercetin, in comparison with authentic samples.

O ácido E-licnofórico 1, seus derivados éster 2 e o álcool 3 eliminaram 100% das formas tripomastigota de Trypanosoma cruzi nas concentrações de 13,86, 5,68 e 6,48 µg/mL, respectivamente. Cálculos (AM1) de distribuição conformacional de 1, 2 e 3 resultaram somente em quatro confôrmeros a, b, c e d como mínimos de energia, que diferem entre si apenas na geometria do anel ciclononeno. Cálculos (DFT/BLYP/6-31G*) de otimização de geometria e de propriedades químicas foram realizados para os confôrmeros de 1, 2 e 3. Esses resultados teóricos foram comparados numericamente com os resultados de atividade tripanossomicida. Valores calculados de densidade eletrônica e cargas atômicas, população orbital e freqüências vibracionais mostraram que o sistema pi-endocíclico (C-4 e C-5) não é um sítio determinante dessa atividade. Entretanto, a estrutura do grupo oxigenado influencia fortemente o potencial de outros sítios do esqueleto cariofilênico. Assim, os cálculos sugerem que o sistema pi-exocíclico (C-8 e C-14) e os carbonos C-1 e C-9 promovem a atividade tripanossomicida dessas substâncias.

E-Lychnophoric acid 1, its derivative ester 2 and alcohol 3 killed 100% of trypomastigote blood forms of Trypanosoma cruzi at the concentrations of 13.86, 5.68, and 6.48 µg/mL, respectively. Conformational distribution calculations (AM1) of 1, 2 and 3 gave minimum energies for the conformers a, b, c, and d, which differ from each other only in the cyclononene ring geometry. Calculations (DFT/BLYP/6-31G*) of geometry optimization and chemical properties were performed for conformers of 1, 2, and 3. The theoretical results were numerically compared to the trypanocidal activity. Calculated values of atomic charge, orbital population, and vibrational frequencies showed that the C-4-C-5 pi-endocyclic bond does not affect the trypanocidal activity of the studied compounds. Nevertheless, the structure of the group at C-4 strongly influences the activity. However, the theoretical results indicated that the intra-ring (C-1 and C-9) and pi-exocycle (C-8 and C-14) carbons of caryophyllene-type structures promote the trypanocidal activity of these compounds.

In this work, the susceptibility to benznidazole of two parental Trypanosoma cruzi strains, Colombian and Berenice-78, was compared to isolates obtained from dogs infected with these strains for several years. In order to evaluate the susceptibility to benznidazole two groups of mice were infected with one of five distinct populations isolated from dogs as well as the two parental strains of T. cruzi. The first group was treated with benznidazole during the acute phase and the second remained untreated controls. The animals were considered cured when parasitological and serological tests remained persistently negative. Mice infected with the Colombian strain and its isolates Colombian (A and B) did not cure after treatment. On the other hand, all animals infected with Berenice-78 were cured by benznidazole treatment. However, 100%, 50% and 70% of cure rates were observed in animals infected with the isolates Berenice-78 B, C and D, respectively. No significant differences were observed in serological profile of infected control groups, with all animals presenting high antibody levels. However, the ELISA test showed differences in serological patterns between mice inoculated with the different T. cruzi isolates and treated with benznidazole. This variability was dependent on the T. cruzi population used and seemed to be associated with the level of resistance to benznidazole.

Como estratégia para a busca de novos agentes tripanossomicidas, de potencial utilização no controle da transmissão transfusional da doença de Chagas, realizou‑se uma triagem dos extratos etanólicos provenientes de espécies vegetais da família Bignoniaceae. Foram avaliadas diferentes metodologias de fracionamento dos extratos etanólicos, tais como, partição entre solventes imisciveis, cromatografias em coluna de poliamida e de gel de sílica, com monitoramento por testes in vitro contra formas tripomastigotas do Trypanosoma cruzi. Os fracionamentos em coluna de gel de sílica do extrato etanólico das folhas de Arrabidaea triplinervia e, posteriormente, da fração eluída desta coluna com diclorometano‑acetato de etila (1:1) resultaram no isolamento de uma substância tripanossomicida, o ácido ursólico (0,76%).

During the period 1980-1986, we captured triatomine bugs and mammalian reservoir hosts from sylvatic and domestic situations in different municipalities of the State of Minas Gerais. Trypanosoma cruzi was isolated from captured bugs, mammals and patients. After cultivation in LIT medium, the electrophoretic enzyme profiles were determined. We obtained atotal of 32 parasite isolates from regions with active domestic transmission, and 24 isolates form areas under control. For the first areas the results suggest introduction of T. cruzi from sylvatic habitats, through incursion of infected opossums and/or sylvatic T. sordida, which appears to have given rise to at least one acute human infection. Of particular interest is the finding of sylvatic opossums and a T. sordida nymph infected with ZB, that could indicate return of parasites from chronic human infections to sylvatic transmission cycles. For the areas under control we also interpret the results as interaction between sylvatic and domestic cycles of transmission, here through the invasion of houses by bugs carrying the Z1 zymodeme from the sylvatic environment. The Multivariate Correspondence Analysis gives a spatial description between the different parasite isolates and confirms the existence of a bridge in the opposite direction in the region with active vectorial transmission including the exporting of Z2 through the peridomestic environment into the sylvatic cycle. For the others areas this bridge corresponds especially to Panstrongylus megistus, importing Z1 into the domestic environment.

The development in C3H mice of thirteen strains of Trypanosoma cruzi belonging to different zymodemes ans schizodemes was studied. Host mortality, virulence, histiotropism, parasitemia and polymorphism of the parasites were recorded. The strains were grouped into: a) high virulence - causing 100% mortality and characterized by predominance of bery broad trypomastigotes in the bloodstream at the end of infection; b) medium virulence - causing no mortality and with a predominance of broad trypomastigotes; c) low virulence - causing no mortality with blood forms not described due to the very low parasitemia. During 18 months maintenance the parasitemia curves were kept constant for all strains except one. A direct correlation between either zymodeme or schizodeme and experimental biological properties of T. cruzi strains was not found. However, the parasitemia was subpatent and patent for strains from zymodeme C and the others respectively. Furthermore the high virulence seems to be related to one of two shizodemes found within zymodeme B strains. All strains presenting patent parasitemia independent of shizodeme and ymodeme showed a myotropism towards heart and skeletal muscle with varible inflammatory intensity. The present study confirmed the heterogeneity found by isoenzyme and K-DNA patterns among the strains of T. cruzi isolated from chagasic patients in Bambuí, Minas Gerais State, Brasil.

A injeção intravenosa de toxina escorpiônica (Tityus serrulatus) em ratos normais e infectados pelo Trypanosoma cruzi não causou alterações morfológicas ultra-estruturáis das células enterocromaflns-like (ECL) do estómago, embora tenha induzido a aumento significativo da secreção do suco gástrico. Nossos resultados parecem indicar que a estrutura das células ECL do estómago de ratos não é afetada pela estimulação com a toxina escorpiônica ou pela infecção aguda pelo T. cruzi.

Intravenous injection of scorpion toxin (Tityus serrulatus) in normal and Trypanosoma cruzi infected rats did not cause ultrastructural morphologic changes on enterochromaffin-like (ECL) cells of the stomach, although it induced a significant increase of the gastric secretion. Our data seem to indicate that gastric ECL cells structure is not affected by stimulation with scorpion toxin or by acute infection with T. cruzi in the rat.

Dez clones isolados das cepas Y, CL e MR foram caracterizados segundo infectividade das culturas, curvas de parasitemia, polimorfismo e mortalidade em camundongos C3H isogênicos. Entra os clones das cepas Y e CL foram encontradas diferenças intragrupos bastante significativas. Os clones da cepa MR apresentaram maior homogeneidade. Estes resultados indicam que as cepas do T. cruzi podem apresentar diferentes graus de heterogeneidade. Também sugerem que as condições utilizadas para a manutenção de cepas de T. cruzi podem resultar em vantagens seletivas para algumas subpopulações, podendo uma cepa ser o resultado da interação destas subpopulações (clones) selecionadas após alguns anos de manutenção em laboratório.

Ten clones of Trypanosoma cruzi isolated from Y, CL and MR strains were studied. The infectivity of culture forms, parasitemia pattern, polymorphism and mortality were studied in C3H inbred mice. Significant intra-group differences among Y and CL clones were found. MR clones showed higher homogeneity. These data indicate that T. cruzi strains can show different degrees of heterogeneity. It is suggested that conditions used to maintain T. cruzi strains may resuly in a selective advantage for some subpopulations (clones) after many years laboratory maintenance.