In vitro gas production of foliage from three browse tree species treated with different dose levels of exogenous fibrolytic enzymes.

The aim of this study was to evaluate the effect of different dose levels of exogenous fibrolytic enzymes (EFE) on in vitro ruminal fermentation kinetics and energy utilization of foliages from three browse trees (Pithecellobium dulce, Heliocarpus velutinus and Guazuma ulmifolia). Mixture of EFE product was added to the leaves of the three browse tree species at three dose levels: 0 (control), 3.5 and 7.0 mg/g of DM. Chemical composition of the foliages, including plant secondary metabolites such as total phenolics (TP), saponins (SAP) and aqueous fraction (AF), was determined. In addition, in vitro assaying of ruminal gas production kinetics was determined for the three browse three foliages treated with EFE. P. dulce had the highest crude protein content (p < 0.05), whereas G. ulmifolia had the highest content of neutral detergent fibre and SAP (p < 0.05) and H. velutinus had the lowest content of TP (p < 0.05). The interaction between tree species and dose level of EFE was significant (p < 0.05) for gas production (GP) at 24 h of incubation, parameters b and c of the accumulated GP curve, short-chain fatty acids (SCFA) and metabolizable energy (ME). The lowest (p < 0.01) extent of accumulated GP as well as the b and c values occurred in G. ulmifolia at 0 mg EFE/g DM. P. dulce had the highest (p < 0.05) values for ME and SCFA at the highest dose of EFE. Tree species and dose level had significant (p < 0.05) effects on all parameters describing in vitro ruminal fermentation kinetics and energy utilization. Addition of EFE improved the fermentation kinetics of the browse species considered in this study.

Lymphoid organ alterations enhanced by sub-lethal doses of coronaviruses in experimentally induced Trypanosoma cruzi infection in mice.

The effect of sub-lethal doses of coronaviruses on the course of disease in CBA mice experimentally infected with a mildly pathogenic strain of Trypanosoma cruzi was investigated. Mice were inoculated with either T. cruzi, 0.1 median lethal dose (LD50) of coronavirus (mouse hepatitis virus [MHV-3] or virus X), or both pathogens. Levels of parasitemia, mortality, and the extent of pathologic alterations in lymphoid organs were determined. Mice inoculated with T. cruzi had mild alterations in their lymphoid organs and survived infection. In contrast, mice inoculated with both pathogens died, and had significantly higher levels of parasitemia and profound alterations in lymphoid organs. These results indicate that the pathologic profile of T. cruzi infection can be profoundly altered by subclinical infection with coronaviruses.

Immunodepression induced by Trypanosoma cruzi and mouse hepatitis virus type 3 is associated with thymus apoptosis.

Trypanosoma cruzi-infected mice show disturbance in the peripheral immune system such as polyclonal lymphocyte activation, autoantibody production, and immunosuppression of T lymphocytes. Previous observations in our laboratory showed that some stocks of T. cruzi can be contaminated with mouse hepatitis virus type 3 (MHV-3). Literature has shown that MHV-3 infection induces immunologic disorders characterized by thymic involution with marked cell depletion. However, the effects of interactions between MHV-3 and the parasite on the immune system are not well understood. In the present study specific-pathogen-free CBA mice were inoculated with MHV-3, alone or associated with different stocks of T. cruzi. Concurrent murine virus infection resulted in increased pathogenicity of T. cruzi infection shown by profound thymic atrophy; loss of cortical thymocytes; depletion of Thy1.2+, CD4+, and CD8+ cells; enhancement of in situ labeling of nuclear DNA fragmentation; and eventually, death of the animals. Such lines of evidence show that the mechanism underlying this thymic atrophy is associated with apoptosis. These results also suggest that MHV-3 can account for the increased immunosuppression observed during experimental infection with the parasite.

Anti-Trypanosoma-cruzi-proteinase antibodies and immunoprotection in experimental Chagas' disease.

To verify whether anti-Trypanosoma-cruzi-proteinase antibodies are able to play a role in the development of Chagas' disease, CBA/J and C57BL/6 mice were immunized with purified proteinase fractions: antibody production was studied and passive immunization experiments were carried out. No significant differences were observed in the titre, isotype composition and specificity of the antibodies produced by the mouse strains. Immune sera produced in one strain was able to protect mice of both strains, provided that the challenge did not exceed the number of parasites corresponding to 30-fold the LD50. The data presented suggest that anti-proteinase antibodies may play a role in immunoprotection.

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)

Isolation and characterization on partially purified leptospiral antigens

Extrato metilico de Leptospira interrogans sorovar canicola foi purificado por precipitacao com acetona ou acetona e cloroformio. A antigenicidade nao foi alterada por aquecimento ou tratamento com pepsina e pronase, entretanto foi perdida quando o antigeno foi tratado com acido periodico. Analise quimica revelou a presenca de 40 por cento de carboidrato (22 por cento de metilpentose, 28 por cento de hexose), 4 por cento de proteina, 20 por cento de lipide e 2,7 por cento de fosfato. Reacao de fixacao de complemento realizada com soros de pacientes com leptospirose apresentou concordancia com a reacao de aglutinacao microscopica.

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.

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.

Experimental Chagas' disease in mice infected with one LD50 of parasite

A evoluçäo da Doença de Chagas em camundongos infectados com dose letal 50% (LD50) de Trypanosoma cruzi cepa Y foi acompanhada determinando-se o nível de parasitemia, alteraçöes hematológicas e o nível de anticorpos anti T.cruzi. Os resultados obtidos demonstraram que os animais apresentam pico de parasitemia no 10 + ou - 2 dias que declina rapidamente. A maioria das mortes ocorreu durante a 3a. semana quando a parasitemia é raramente detectada em esfregaços sanguíneos. A comparaçäo dos dados hematológicos obtidos dos animais infectados com os dos controles correspondentes indicou a ocorrência de leve anemia (2a. a 6a. semanas), neutropenia (2a. semana) seguido por neutrofília (3a. semana) e eosinopenia (2a. a 5a. semana). Os soros dos animais infectados testados por imunofluorescência com as três formas do parasito mostraram títulos crescentes de anticorpos a partir da 3a. semana. Experiências de absorçäo cruzada mostraram que os tripomastigotas e amastigotas tem determinantes antigênicos próprios. Além disso essas formas possuem determinantes que säo comuns à forma epimastigota. O soro dos animais infectados apresentou reaçäo de precipitaçäo quando testado com a fraçäo (Fad) que contém glicopeptídeos do extrato de epimastigota ao passo que nenhuma reaçäo foi observada quando testado com a proteinase purificada a partir deste mesmo extrato

Utilizacao da fracao semipurificada da proteinase do Trypanosoma cruzi no imunodiagnostico da doenca de Chagas. / Use of the semipurifiec fraction of Trypanosoma cruzi proteinase in the immunodiagnosis of Chagas' disease

Foram sensibilizadas hemacias humanas 0 Rh negativo com a fracao semipurificada (Fp) da proteinase do Trypanosoma cruzi, e testadas quanto a antigenicidade com soros de pacientes portadores de tripanossomiase americana cronica e de outras doencas parasitarias nao relacionadas.Reacoes de hemaglutinacao positivas foram observadas com os soros de pacientes chagasicos e com alguns soros de individuos portadores de leishmaniose cutaneomucosa. Nao foram observadas reacoes cruzadas com os soros de pacientes portadores de leishmaniose visceral, malaria, toxoplasmose, sifilis, esquistossomose e mononucleose.Os resultados obtidos sao favoraveis ao emprego desta fracao antigenica em testes da imunodiagnostico da tripanossomiase americana

Evolucao das imunoglobulinas envolvidas na resposta imune de camundongos a Schistosoma mansoni. / Evaluation of immunoglobulins involved in the immune response of mice to Schistosoma mansoni

Foi estudada a evolucao as 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, contituida pelas IgA; IgG1 e IgM, com aumentos relativos de 4.5; 3 e 2 vezes normal

Purificacao da enterotoxina termo-estavel (ST) de Escherichia coli. / Purification study thermostable (ST) enteroxin of Escherichia coli

A enterotoxina termo-estavel (ST) de E.coli, proveniente de amostra humana, foi parcialmente purificada por cromatografia em coluna de permutador anionico, equilibrado com acetato de amonio 0,01M, pH 9, dialise em sacos tratados com piridina e andrido acetico (V/V) e filtracao em coluna de Sephadex G-15 foi examinado por cromatografia descendente em papel, no sistema de solventes acido acetico, butanol e agua (1:4:5). Conseguiu-se distinguir diversas substancias presentes na amostra e localizar, apos eluicao e analise pelo teste do camundongo recem-nascido, a mancha correspondente a enterotoxina ST. Em recromatografia da toxina ST eluida, no mesmo solvente, obteve-se apenas uma mancha. Entretanto, em vista do baixo rendimento observado neste ultimo metodo, o seu uso deve ser indicado, apenas como um processo analitico da purificacao de ST

Esquistossomose mansonica. II - Evolucao dos niveis de proteinas sericas e do perfil eletroforetico por tecnicas de imunoeletroforese quantitativa. / Schistosomiasis mansoni. II. Evolution of the levels of serum proteins and of the electrophoretic profile by quantitative immunoelectrophoresis technics

Camundongos Swiss foram infectados com 100 cercarias da linhagem mineira (BH) do Schistosoma mansoni e sacrificados semanalmente no periodo de 8 semanas de infeccao. Os niveis de proteinas sericas totais destes animais nao diferiram dos apresentados pelos animais controles. Os niveis de albumina serica determinados por "Rocket immunoelectrophoresis" acharam-se diminuidos nas quinta, sexta e setima semanas de infeccao. O perfil obtido por imunoeletroforese cruzada revelou alteracoes em componentes sericos com mobilidade nas regioes de gama, beta e em menor grau de alfaglobulinas, apos a oviposicao do parasito

Evolucao dos esporocistos de Schistosoma mansoni Sambon, 1907 em Biomphalaria glabrata (Say, 1818) e Biomphalaria tenagophila (D'Orbigny, 1835). / Evolution of sporocysts of Schistosoma mansoni Sambon, 1907 in Biomphalaria glabrata (Say, 1818) and 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 o 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

Diagnóstico da esquistossomose mansonica mediante tecnica de imunofluorescencia com esporocitos em tecidos de planorbideos. / Diagnosis of schistosomiasis mansoni by immunofluorescent technic with sporocysts in planorbid tissues

Propoe-se uma tecnica de imunofluorescencia para diagnostico da esquistossomose mansonica adotando-se tecidos de Biomphalaria glabrata contendo esporocistos secundarios de Schistosoma mansoni. A reacao de imunofluorescencia indireta e executada sobre cortes histologicos preparados por inclusao em parafina