Different infective forms trigger distinct immune response in experimental Chagas disease.

Although metacyclic and blood trypomastigotes are completely functional in relation to parasite-host interaction and/or target cell invasion, they differ in the molecules present on the surface. Thus, aspects related to the variability that the forms of T. cruzi interacts with host cells may lead to fundamental implications on the immune response against this parasite and, consequently, the clinical evolution of Chagas disease. We have shown that BT infected mice presented higher levels of parasitemia during all the acute phase of infection. Moreover, the infection with either MT or BT forms resulted in increased levels of total leukocytes, monocytes and lymphocytes, specifically later for MT and earlier for BT. The infection with BT forms presented earlier production of proinflammatory cytokine TNF-α and later of IFN-γ by both T cells subpopulations. This event was accompanied by an early cardiac inflammation with an exacerbation of this process at the end of the acute phase. On the other hand, infection with MT forms result in an early production of IFN-γ, with subsequent control in the production of this cytokine by IL-10, which provided to these animals an immunomodulatory profile in the end of the acute phase. These results are in agreement with what was found for cardiac inflammation where animals infected with MT forms showed intense cardiac inflammation later at infection, with a decrease in the same at the end of this phase. In summary, our findings emphasize the importance of taking into account the inoculums source of T. cruzi, since vectorial or transfusional routes of T. cruzi infection may trigger distinct parasite-host interactions during the acute phase that may influence relevant biological aspects of chronic Chagas disease

Increase of reactive oxygen species by desferrioxamine during experimental Chagas' disease.

Oxidative stress is common in inflammatory processes associated with many diseases including Chagas' disease. The aim of the present study was to evaluate, in a murine model, biomarkers of oxidative stress together with components of the antioxidant system in order to provide an overview of the mechanism of action of the iron chelator desferrioxamine (DFO). The study population comprised 48 male Swiss mice, half of which were treated daily by intraperitoneal injection of DFO over a 35-day period, while half were administered sterile water in a similar manner. On the 14th day of the experiment, 12 DFO-treated mice and an equal number of untreated mice were experimentally infected with Trypanosoma cruzi. Serum concentrations of nitric oxide and superoxide dismutase and hepatic levels of total glutathione, thiobarbituric acid reactive species and protein carbonyl, were determined on days 0, 7, 14 and 21 post-infection. The results obtained revealed that DFO enhances antioxidant activity in the host but also increases oxidative stress, indicating that the mode of action of the drug involves a positive contribution to the host together with an effect that is not beneficial to the parasite

The effect of benznidazole dose among the efficacy outcome in the murine animal model. A quantitative integration of the literature.

Despite more than 100 years since it was firstly described Chagas disease, only two drugs are available to treat Chagas disease: Nifurtimox launched by Bayer in 1965 and benznidazole launched by Roche in 1971. Drug discovery initiatives have been looking for new compounds as an alternative to these old drugs. Although new platforms have been used with the latest technologies, a critical step on that process still relies on the in vivo model. Unfortunately, to date, available animal models have limited predictive value and there is no standardization. With the aim to better understand the role of benznidazole, the current standard of care of Chagas disease, we performed this review. We intend to analyze the influence of the experimental design of the most used animal model, the murine model, in the assessment of the efficacy endpoint

Benznidazole Treatment : Time- and Dose-Dependence Varies with the Trypanosoma cruzi Strain

As the development of new drugs for Chagas disease is not a priority due to its neglected disease status, an option for increasing treatment adherence is to explore alternative treatment regimens, which may decrease the incidence of side effects. Therefore, we evaluated the efficacy of different therapeutic schemes with benznidazole (BNZ) on the acute and chronic phases of the disease, using mice infected with strains that have different BNZ susceptibilities. Our results show that the groups of animals infected by VL-10 strain, when treated in the chronic phase with a lower dose of BNZ for a longer period of time (40 mg/kg/day for 40 days) presented better treatment efficacy than with the standard protocol (100 mg/kg/day for 20 days) although the best result in the treatment of the animals infected by the VL-10 strain was with100 mg/kg/day for 40 days. In the acute infection by the Y and VL-10 strains of T. cruzi, the treatment with a standard dose, but with a longer time of treatment (100 mg/kg/day for 40 days) presented the best results. Given these data, our results indicate that for BNZ, the theory of dose and time proportionality does not apply to the phases of infectio

Trypanosoma cruzi: desferrioxamine decreases mortality and parasitemia in infected mice through a trypanostatic effect.

Desferrioxamine (DFO) is a potent iron chelator that is also known to modulate inflammation and act as an efficient antioxidant under normal conditions and under oxidative stress. Many in vitro and in vivo studies have shown the efficacy of DFO in the treatment of viral, bacterial and protozoan infections. DFO is known to reduce the intensity of Trypanosoma cruzi infections in mice even during a course of therapy that is not effective in maintaining anaemia or low iron levels. To further clarify these findings, we investigated the action of DFO on mouse T. cruzi infection outcomes and the direct impact of DFO on parasites. Infected animals treated with DFO (5 mg/animal/day) for 35 days, beginning 14 days prior to infection, presented lower parasitemia and lower cumulative mortality rate. No significant effect was observed on iron metabolism markers, erythrograms, leukograms or lymphocyte subsets. In the rapid method for testing in vivo T. cruzi susceptibility, DFO also induced lower parasitemia. In regard to its direct impact on parasites, DFO slightly inhibited the growth of amastigotes and trypomastigotes in fibroblast culture. Trypan blue staining showed no effects of DFO on parasite viability, and only minor apoptosis in trypomastigotes was observed. Nevertheless, a clear decrease in parasite mobility was detected. In conclusion, the beneficial actions of DFO on mice T. cruzi infection seem to be independent of host iron metabolism and free of significant haematological side effects. Through direct action on the parasite, DFO has more effective trypanostatic than trypanocidal properties

Acute and sub chronic toxicity study of aqueous extract from the leaves and branches of Campomanesia velutina (Cambess) O. Berg.

Ethnopharmacological relevance: Campomanesia velutina leaves and branches infusions are used in Brazilian folk medicine to treat diarrhea and to ameliorate intestinal cramps, respectively. Aim of the study: Carry out the acute and sub chronic pre-clinical evaluation and thus assess the safety and toxicological potential of the specie. Materials and methods: In vivo toxicity was evaluated by acute and sub chronic toxicity assays conducted according to the guidelines of the Brazilian Agency of National Health Surveillance (Ag?ncia Nacional de Vigil?ncia Sanit?ria ? ANVISA). For acute toxicity evaluation, a single dose of aqueous extracts from the leaves (AEL) and branches (AEB) of Campomanesia velutina were orally administered to mice at doses of 300, 600 and 1200 mg/kg. Then, the animals were observed for 14 days. In the sub chronic study, the extracts were orally administered to mice for 14 days at doses of 300, 600 and 1200 mg/kg. To assess the toxicological effects, animals were closely observed on general behavior, clinical signs of toxicity, body weight, food and water intake. At the end of the experiment, it was performed biochemical and hematological evaluations, as well as histopathological analysis from the following organs: brain, heart, lungs, liver, stomach, small intestine (section) and left kidney. Preliminary phytochemical analysis was performed using thin layer chromatography (TLC) and colorimetric pharmacognostic tests. Results: In oral acute assay, treatment with AEB at the major dose (1200 mg/kg) caused diarrhea, abdominal cramps and tremors in females. These effects were reversed at 4th hour. Normochromic normocytic anemia was observed in males treated with AEL 300 mg/kg and AEB 600 and 1200 mg/kg as well as in females treated with AEB 300 and 1200 mg/kg. The kidney of all treated animals showed moderate inflammation and a few hemorrhagic points. In sub chronic assay, treatment with AEL 600 mg/kg, AEL 1200 mg/kg and AEB 1200 mg/kg caused hyper excitability in females that was not reversed. Treatments also had impact on weight gain and the relative weight of males? brain was increased on group treated with AEL 300 mg/kg, AEB 300 and AEB 1200 mg/kg. Although changes in hematological parameters were not observed, serum creatinine levels were significantly higher in males treated with AEB 300 mg/kg. Besides, the heart of all treated animals showed intense hyperemia. Preliminary phytochemical analysis revealed the presence of flavonoids, tannins and phenolic compounds. Conclusions: Toxicity signs were mainly observed after treatment with AEL and AEB at the two highest tested doses (600 and 1200 mg/kg), suggesting that the extracts are relatively safe at its effective dose (300 mg/kg). However, alterations on hematological and biochemical parameters and on the kidney and heart of the animals were not closely related with the dose, implying caution on its use

Uma proposição didática para o ensino de fisiologia na realidade da educação no campo / A teaching proposition for teaching physiology in the reality of education in the field

A ementa de fisiologia, geralmente correspondente ao oitavo ano do Ensino Fundamental é extremamente desafiadora, especialmente nos tópicos sobre o sistema endócrino, o qual estuda a composição hormonal em certos organismos. Para esses estudantes, o tema em questão pode ser demasiadamente abstrato, tendo em vista que é necessário a compreensão de diversos outros para que haja uma efetiva compreensão dos mecanismos fisiológicos. Deste modo, o objetivo deste trabalho é pontuar uma estratégia didática que pode ser utilizada em escolas de zona rural, contextualizando os conhecimentos científicos à realidade dos estudantes da Educação no Campo. Nesse sentido, acreditamos que práticas como essas podem contribuir positivamente para um ensino e aprendizado significativo, concorrendo para a alfabetização científica, tanto por parte dos estudantes, quanto dos próprios produtores, além de beneficiar por meio do conhecimento científico, uma comunidade inserida nos saberes da Educação no Campo.

BRSMG Uai: common bean cultivar with carioca grain type and upright plant architecture

The common bean cultivar with carioca grain type, BRSMG Uai, is recommended for cultivation in Minas Gerais and stands out for its upright plant architecture, which facilitates cultivation and mechanical harvesting. This cultivar has high yield potential and is resistant to the major races of anthracnose that occur in region

Valor de cultivo e uso de linhagens de feijoeiro de grãos tipo carioca em Minas Gerais no período de 2010 a 2012.

Nesse trabalho são apresentados os resultados dos ensaios de VCU de feijão tipo carioca conduzidos em Minas Gerais pela UFLA, UFV, Embrapa e Epamig nos anos de 2010 a 2012, visando a indicação de nova cultivar com esse tipo de grão para o estado. Foram avaliadas 20 novas linhagens de feijoeiro juntamente com as testemunhas Pérola, BRSMG Talismã, BRSMG Majestoso e BRSMG Madrepérola, já registradas para o estado de Minas Gerais, e a cultivar BRS Notável, registrada para cultivo em outros estados