RESUMO
The effects of the triazolodiazepine WEB 2086, a platelet-activating factor (PAF) antagonist, on hemocyte microaggregation and prophenoloxidase (proPO)-activating system in the hemolymph, hemocoelic infection and mortality in fifth-instar larvae of Rhodnius prolixus inoculated with Trypanosoma rangeli were investigated. Hemocoelic injection of short T. rangeli epimastigotes (1x10(4) parasites/insect) in R. prolixus that were previously fed with blood containing 1muM of WEB 2086 resulted in (i) reduced hemocyte microaggregations as well as an attenuated proPO system in the hemolymph and (ii) greater parasitemia and mortality among the insects. In vitro assays using hemolymph from insects previously fed with blood containing WEB 2086 exhibited attenuated hemocyte microaggregations when T. rangeli was employed as the inducer of the reaction, and this effect was not counteracted by PAF treatment. In vitro assays using hemolymph from insects previously fed with blood, regardless of WEB 2086 presence increased the PO activity when incubated with the parasites. However, the PO activity was drastically inhibited when hemolymph from insects fed with blood, whether or not it contained WEB 2086, was incubated with fat body homogenates from insects fed with blood containing WEB 2086. The addition of PAF did not enhance the PO activity. These analyses did not reveal any PAF influence on WEB 2086 effects in the two defense reactions.
Assuntos
Azepinas/farmacologia , Catecol Oxidase/fisiologia , Precursores Enzimáticos/fisiologia , Hemócitos/fisiologia , Fator de Ativação de Plaquetas/fisiologia , Inibidores da Agregação Plaquetária/farmacologia , Rhodnius/imunologia , Triazóis/farmacologia , Trypanosoma/fisiologia , Animais , Catecol Oxidase/metabolismo , Precursores Enzimáticos/metabolismo , Hemolinfa/imunologia , Larva/imunologia , Larva/parasitologia , Fator de Ativação de Plaquetas/antagonistas & inibidores , Rhodnius/parasitologiaRESUMO
Cathepsin D activity was estimated in midgut homogenates from Rhodnius prolixus, uninfected and experimentally infected with Trypanosoma cruzi, at different times after blood ingestion. No enzyme activity was found in the anterior midgut and rectum. In the posterior midgut, enzyme activity was found both in lumen and wall. In starved uninfected insects, in lumen and wall, cathepsin D activity was high, decreasing to a constant rate at 1-15 days after feeding. In insects infected with T. cruzi cathepsin D activity increased 1 and 3 days after blood meal. We suggest that these changes in cathepsin D activity in R. prolixus posterior midgut are due to the establishment of T. cruzi infection.
Assuntos
Catepsina D/metabolismo , Insetos Vetores/enzimologia , Insetos Vetores/parasitologia , Rhodnius/enzimologia , Rhodnius/parasitologia , Trypanosoma cruzi/fisiologia , Animais , HumanosRESUMO
Hemocoelic inoculation of epimastigotes of Trypanosoma rangeli strain H14 into 5th-instar larvae of Rhodnius prolixus previously fed on blood containing the same parasites, showed reduced number of hemocyte microaggregates in the hemolymph, enhanced number of flagellates in the hemolymph as well as increased mortality of these insects. All these effects were counteracted by combined inoculation of R. prolixus with T. rangeli and arachidonic acid. In vitro assays using hemolymph taken from insects previously fed on blood containing parasites showed that hemocyte microaggregation reactions were also attenuated when T. rangeli is used as inducer of the reaction, and that simultaneous applying T. rangeli with arachidonic counteracted the hemocyte microaggregation inhibition. We suggest that arachidonic acid pathway can be a mediator of hemocyte microaggregation reactions in the hemolymph of insects inoculated with T. rangeli, and that oral infection with this protozoan inhibits the release of arachidonic acid.
Assuntos
Ácido Araquidônico/metabolismo , Hemócitos/metabolismo , Insetos Vetores/parasitologia , Rhodnius/parasitologia , Trypanosoma/fisiologia , Animais , Ácido Araquidônico/farmacologia , Agregação Celular/efeitos dos fármacos , Hemócitos/efeitos dos fármacos , Hemócitos/imunologia , Hemolinfa/citologia , Hemolinfa/imunologia , Hemolinfa/parasitologia , Humanos , Imunidade Celular , Insetos Vetores/citologia , Insetos Vetores/imunologia , Larva/citologia , Larva/imunologia , Larva/parasitologia , Rhodnius/citologia , Rhodnius/imunologia , Trypanosoma/imunologiaRESUMO
Investigations on the effects of eicosanoid biosynthesis inhibitors on the hemocyte microaggregation and prophenoloxidase (proPO)-activating system in the hemolymph, parasitemia and mortality of Rhodnius prolixus infected with Trypanosoma rangeli were performed. Hemocoelic injection of live T. rangeli epimastigotes into fifth-instar larvae of R. prolixus that previously fed on blood containing an inhibitor of phospholipase A(2) (dexamethasone), a specific inhibitor of the cyclooxygenase pathway (indomethacin), and a non-selective lipoxygenase inhibitor (NDGA) (i) reduced the hemocyte microaggregation, (ii) attenuated the proPO system in the hemolymph and (iii) enhanced parasitemia and mortality induced by the parasite challenge in these insects. The effects obtained by dexamethasone administered orally were counteracted by inoculation of the insects with arachidonic acid. We suggest that the infectivity of T. rangeli can be increased by interference with the R. prolixus immune system. This is the first demonstration that the triatomine's immune responses to a parasite infection are modulated by a physiological system that includes eicosanoid biosynthesis.
Assuntos
Eicosanoides/antagonistas & inibidores , Eicosanoides/imunologia , Hemolinfa/imunologia , Insetos Vetores/imunologia , Rhodnius/imunologia , Serina Endopeptidases/efeitos dos fármacos , Tripanossomíase/imunologia , Animais , Ácido Araquidônico/metabolismo , Contagem de Células Sanguíneas , Dexametasona/farmacologia , Suscetibilidade a Doenças , Eicosanoides/biossíntese , Inibidores Enzimáticos/farmacologia , Hemócitos/imunologia , Hemolinfa/enzimologia , Indometacina/farmacologia , Insetos Vetores/enzimologia , Insetos Vetores/parasitologia , Masoprocol/farmacologia , Rhodnius/enzimologia , Rhodnius/parasitologia , Transdução de Sinais/imunologiaRESUMO
The history and present situation of Chagas' disease in Lassance (the county where Carlos Chagas discovered American trypanosomiasis) were studied through a historical analysis and clinical and epidemiological research performed from 1999 to 2001. Lassance was an important focus of Chagas' disease from Carlos Chagas up until the 1980's, because of intensive infestation in dwellings by Panstrongylus megistus and Triatoma infestans, two important species which were efficiently controlled in the last twenty years. Human Chagas' disease was important in the past but today is only residual, affecting basically the more elderly age groups. The general prevalence is about 5.03% and no infected individuals are found below 20 years of age. The clinical and epidemiologic profile of the seropositive individuals studied is that expected in areas with interrupted transmission, most of these presenting the indeterminate or benign cardiac form of chronic Chagas' disease. Some cases of digestive Chagas' disease also seem to exist. Mortality due to the disease is still significant, affecting chiefly older age groups. The municipality still remains infested by Triatoma sordida, in low densities and high dispersion, non infected by T. cruzi and restricted to peridomestic foci. In conclusion, Lassance is now free of Chagas' disease transmission and must improve medical attention for the remaining infected individuals, as well as to maintain a permanent epidemiological surveillance against native Triatominae.
Assuntos
Doença de Chagas/diagnóstico , Doença de Chagas/epidemiologia , Adolescente , Adulto , Brasil/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de TempoRESUMO
Analisa-se a trajetória da doença de Chagas em Lassance (município da descoberta de Carlos Chagas) entre 1.908 a 2.001, através de registros históricos e pesquisas atuais. O município foi importante foco da tripanossomíase entre Chagas e os anos 1.980, mercê de infestaçäo significativa das casas por Panstrongylus megistus e, mais tarde, Triatoma infestans, espécies que foram eficazmente controladas, nos últimos 20 anos. Importante no passado, a infecçäo chagásica é hoje residual, com uma prevalência geral de 5,03 por cento e afetando basicamente os grupos etários elevados, näo se encontrando soropositivos abaixo dos 20 anos de idade. O perfil clínico-epidemiológico dos chagásicos detectados é o habitual de áreas com transmissäo interrompida, com a maioria dos casos em formas cardíacas benignas ou na forma crônica indeterminada, havendo ainda indicativos de formas digestivas, sendo a mortalidade ainda significativa, em grupos etários elevados. O município apresenta-se infestado por T. sordida, em baixas densidades e grande dispersäo, näo infectado por T. cruzi e restrito ao peridomicílio. Conclui-se que Lassance está hoje livre da transmissäo da doença, devendo manter-se sob vigilância epidemiológica frente aos triatomíneos nativos no município e garantir-se a atençäo médica às pessoas infectadas no passado
Assuntos
Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doença de Chagas/diagnóstico , Doença de Chagas/epidemiologia , Brasil/epidemiologia , Fatores de TempoRESUMO
We carried out a morphometric study of the esophagus of cross-bred dogs experimentally infected or consecutively reinfected with Trypanosoma cruzi 147 and SC-1 strains, in order to verify denervation and/or neuronal hypertrophy in the intramural plexus. The animals were sacrificed in the chronic stage, 38 months after the initial infection. Neither nests of amastigotes, nor myositis or ganglionitis, were observed in all third inferior portions of esophageal rings analyzed. No nerve cell was identified in the submucous of this organ. There was no significant difference (p>0.05) between the number, maximum diameter, perimeter, or area and volume of the nerve cells of the myenteric plexus of infected and/or reinfected dogs and of the non-infected ones. In view of these results we may conclude that the 147 and SC-1 strains have little neurotropism and do not determine denervation and/or hypertrophy in the intramural esophageal plexuses in the animals studied, independent of the reinfections
Assuntos
Animais , Masculino , Feminino , Cães , Doença de Chagas/veterinária , Doenças do Cão/patologia , Esôfago/inervação , Plexo Mientérico/patologia , Plexo Submucoso/patologia , Doença de Chagas/patologia , Esôfago/patologia , Recidiva , Trypanosoma cruziRESUMO
Due to the overlapping distribution of Trypanosoma rangeli and T. cruzi in Central and South America, sharing several reservoirs and triatomine vectors, we herein describe a simple method to collect triatomine feces and hemolymph in filter paper for further detection and specific characterization of these two trypanosomes. Experimentally infected triatomines feces and hemolymph were collected in filter paper and specific detection of T. rangeli or T. cruzi DNA by polymerase chain reaction was achieved. This simple DNA collection method allows sample collection in the field and further specific trypanosome detection and characterization in the laboratory
Assuntos
Animais , DNA/isolamento & purificação , Insetos Vetores/parasitologia , Reação em Cadeia da Polimerase , Triatominae/parasitologia , Trypanosoma/isolamento & purificação , Fezes/parasitologia , Hemolinfa/parasitologia , Trypanosoma cruzi/genética , Trypanosoma cruzi/isolamento & purificação , Trypanosoma/genéticaRESUMO
Apresentam-se dados primários e secundários da Doença de Chagas no Nordeste do Brasil, com prioridade para o vetor, a transmissäo e o controle. Assinalam-se 27 espécies vetoras, com importância basicamente para Triatoma infestans, Panstrongylus megistus, Triatoma brasiliensis e Triatoma pseudomaculata. As duas primeiras foram mais domiciliadas, causaram mais impacto médico-social e têm sido eliminadas mediante continuado controle químico. As duas últimas säo nativas, ubiqüistas e mais peridomésticas, de difícil controle e menor impacto, remanescendo como grande desafio operacional. Há diversidade nos padröes de transmissäo e da doença na regiäo, explicáveis por diferentes situaçöes ecológicas e sociais, possivelmente envolvendo diferentes cepas de Trypanosoma cruzi. A doença de Chagas é importante no Nordeste, embora com menor morbi-mortalidade aparente que no Sudeste e em Goiás. Há uma tendência à diminuiçäo da transmissäo e impacto da doença na regiäo, mas preocupa a progressiva desativaçäo regional da Fundaçäo Nacional de Saúde, sem a correspondente absorçäo de suas atividades pelos Estados e municípios.