Humberto de Araújo Rangel

Trypanosoma cruzi: Isolation and characterization of a proteinase

Abstract Lysates of Trypanosoma cruzi epimastigotes were able to hydrolyze casein (Km = 2.5 mg/ml) as well as bovine and human hemoglobins (Km = 12.2 mg/ml); there was optimum activity was around pH 7.0. The proteinase activity detected with these substrates was enhanced by sodium diaminotetraacetate (EDTA) and reducing agents (SO2−3, mercaptoethanol, cysteine) and was inhibited by sulfhydryl reagents, thus suggesting an SH-dependent enzyme. Purification (60×) of the proteinase was carried out as follows: (1) precipitation at −20 C, pH 4.5, with 80% acetone, (2) gel filtration on Sephadex G-200, (3) affinity chromatography on Sepharose 4B covalently linked to p-aminophenyl mercuric acetate. Only a single component (with an estimated molecular weight of 60,000) was detected in purified preparations by polyacrylamide gel electrophoresis. However, in addition to the major component identified as a proteinase, crossed immunoelectrophoresis experiments indicated the presence of at least three other antigens that apparently were devoid of proteinase activity. Optimum pH activity of the purified preparations was around pH 6.0 for casein and pH 3.0 for hemoglobins, but these activities probably are due to the one enzyme since they were altered identically by the same agents.

Evolução dos esporocistos de Schistosoma mansoni Sambon, 1907 em Biomphalaria glabrata (Say, 1818) e Biomphalaria tenagophila (D'Orbigny, 1835)

Estudou-se a evolucao dos esporocistos de Shistosoma mansoni das linhagens BH e SJ respectivamente em Biomphalaria glabrata e Biomphalaria tenagophila. Utilizando-se cortes histologicos foram avaliados o aspecto e numero de esporocistos primarios desde a primeira ate a oitava semana de infeccao, a contar do dia em que cada molusco foi exposto a 100 miracidios. No decorrer da primeira semana constataram-se diferencas significativas entre as linhagens estudadas quanto ao numero e aspecto dos esporocistos primarios, A distribuicao por orgaos e a evolucao dos esporocistos foi observada ate a fase de formacao das cercarias infectantes.

Immunological comparison of hemorrhagic principles present in venoms of the Crotalinae and Viperinae subfamilies

Antibodies were raised against hemorrhagic factors HF1, HF2 and HF3 isolated from the venom of Bothrops jararaca and NHFa,b from the venom of Bothrops neuwiedi. Crude venoms of different species of snakes were assayed with the rabbit antisera specific for the hemorrhagic factors. Results of immunodiffusion, neutralization of hemorrhagic activity and micro-complement fixation indicated that there is an immunological relationship between the venom hemorrhagic components of the Bothrops species and those of other species of the Crotalinae subfamily. The factors of Bothrops species seem to be structurally similar. The hemorrhagic proteins from the venoms of Lachesis, North American Crotalus, Asian Trimeresurus and Agkistrodon species show some resemblance to the Bothrops factors. The venom hemorrhagic principles from snakes of the Viperinae subfamily (Bitis and Vipera species) might have few epitopes similar to those of Bothrops species as the only relation shown was the partial neutralization by the immune sera.

Seleção de linhagens de Biomphalaria tenagophila e Biompnalaria glabrata visando maior suscetibilidade ao Schistosoma mansoni

Utilizando um esquema de selecao individual em progenies autofecundadas, foram obtidas, apos quatro geracoes, populacoes de Biomphalaria tenagophila e de Biomphalaria glabrata, altamente suscetiveis as linhagens do Schistosoma mansoni do Vale do Rio Paraiba do Sul, SP e de Belo Horizonte, MG (Brasil), respectivamente. Os rapidos ganhos geneticos obtidos confirmam ser a suscetibilidade de moluscos a infeccao esquistossomotica, uma caracteristica de alta herdabilidade, sendo aparentemente condicionada por um pequeno numero de genes.

Caminho para a construção coletiva de ambientes saudáveis: São Paulo, Brasil

O trabalho mostra estrategias de construir espacos saudaveis por meio de uma parceria estabelecida entre OPAS, Unicamp, IPES e Comunidades/Cidades. Um dos projetos ocorrem em Campinas (SP), em uma regiao formada por bairros carentes, onde esta sendo implantado o projeto Comunidade Saudavel e outro, envolve mais de 18 municipios que se constituem a Rede de Municipios Potencialmente Saudaveis. O exercicio de implantacao desses projetos tem sido um aprendizado coletivo, pois professores, representantes dos servicos publicos, outras organizacoes e comunidades/municipios devem rever objetivos e desejos na direcao do saudavel.

Trypanosoma cruzi: Early resistance induced by culture-derived trypomastigotes

Previous observations in this laboratory showed that injection of culture-derived trypomastigotes (CT), in CBA/J mice, induced an early increased resistance that was detected 24-72 hr after antigen injection and permitted mice to survive a challenge of 10(5) blood trypomastigotes (BT) corresponding to 2000 LD50%. Present experiments were conducted to determine the optimal conditions for inducing this early resistance and to investigate the early morphological changes which occurred in blood and lymphoid organs of mice infected with either BT or CT. Among nine antigens tested, only living CT showed a protective effect permitting most of mice to survive 30 days after BT challenge, while control mice injected with PBS or other antigens died at 10 +/- 1 days. A dose-response relationship was seen when different doses of CT were tested, higher doses of CT inducing higher survival and lower parasitemia. Injection of CT by either an im or ip route induced similar degrees of resistance but significantly different results were obtained when mice were challenged by using ip or im routes. Higher parasitemia and lower survival were always obtained when animals were challenged by the ip route. Within 72 hr, mice injected with BT presented a lymphopenia which reached a maximum at 48 hr, a depletion of thymic cortical zone, and splenomegaly with hyperplasia of the white pulp and congestion of the red pulp. No gross alterations were observed in animals infected with CT. Overall data suggest that the early resistance is a specifically induced phenomenon and that BT and CT induce different early reactions in the CBA/J lymphoid organs.(ABSTRACT TRUNCATED AT 250 WORDS)

Evolução das imunoglobunilas envolvidas na resposta imune de camundongos ao Schistosoma mansoni

Foi estudada a evolucao das imunoglobulinas envolvidas na resposta imune de camundongos ao Schistosoma mansoni durante oito semanas de infeccao, utilizando soros pluri-especificos como reativos biologicos e a tecnica da imunoeletroforese bidimensional. Os resultados expressaram modulacao da resposta imune humoral, tanto em soros de animais parasitados (I) como nos normais, tomados como controle (C). Aumentos relativos dos niveis de imunoglobulinas entre estes dois grupos foram constatados pela relacao I/C. Foi possivel verificar o aparecimento de uma resposta primaria, ocorrida entre o inicio da doenca e a segunda semana de infeccao, constituida de IgM e IgA, e uma secundaria, iniciada na sexta semana de infeccao, constituida pelas IgA; IgG1 e IgM, com aumentos relativos de 4.5; 3 e 2 vezes normal.The evolution of immunoglobulins involved in the immune response of mice infected with Schistosoma mansoni was studied by using plurispecific sera and the bi-dimensional immunoelectrophoresis technique. Determinations of the level of different immunoglobulins in infected animals and control groups which were mantained under similar conditions detected significant variations in both groups over the 8 weeks of observation. The study of the relationship (I/C) between the level of immunoglobulins of the infected animals (I) and that of corresponding control (C) showed that the infected animals presented a primary response (1-2 weeks after infection date) and a secondary response that was initiated in the 6th week of infection, with levels of IgA, IgG and IgM that were respectively 4.5, 3 and 2 times higher than those of corresponding control.

The early phase of the immune response of CBA miceinfected with Trypanosoma cruzi

Mice injected with 10(5) culture trypomastigotes (CT) survived the 30-day observation period while those injected with the same number of bloodstream trypomastigotes (BT) died in 10 +/- 1 days. As early as 24 h after injection of CT the mice displayed an increased resistance to Trypanosoma cruzi as indicated by an increased longevity when challenged with lethal doses of BT. The phagocytic activity of mice injected 24-72 h earlier with CT is increased, while that of mice injected with BT is decreased. The data suggest that parasite factors acting on the early phase of the immune response play a role in the outcome of the infection.

Murine virus contaminant of Trypanosoma cruzi experimental infection

The possibility that some virus contaminants could be altering host response to Trypanosoma cruzi experimental infection was investigated. Data obtained showed that CBA/J mice infected with stocks of parasite maintained in mice (YIUEC) presented higher level of parasitemia and shorter survival times than those infected with a stock (YITC) which was also maintained in mice but had been previously passaged in cell culture. Mouse antibody production tests, performed with the filtered plasma of mice infected with YIUEC, indicated the presence of mouse hepatitis virus (MHV) while no virus was detected when testing the plasma of YITC infected mice. Filtered plasma of YIEUC infected mice was shown to contain a factor able to enhance the level of parasitemia and to reduce the mean survival time of mice challenged with 10(5) YITC. This factor, that could be serially passaged to naïve mice was shown to be a coronavirus by neutralization tests.

Isolation and characterization of partially purified leptospiral antigens

The methanol extract of Leptospira interrogans serovar canicola was purified by precipitation with acetone or acetone and chloroform. The antigenicity of the antigen was not altered by heating or treatment with pepsin and pronase. However the antigenicity was lost when the antigen was treated with periodic acid. Chemical analysis revealed the presence of 40% carbohydrate (22% methylpentose, 28% hexoses), 4% protein, 20% lipid and 2.7% phosphate. The complement fixation test with sera from patients with leptospirosis agreed with the microscopic agglutination reaction.