Trypanosoma cruzi-cardiomyocytes: new contributions regarding a better understanding of this interaction

The present paper summarizes new approaches regarding the progress done to the understanding of the interaction of Trypanosoma cruzi-cardiomyocytes. Mannose receptors localized at the surface of heart muscle cell are involved in binding and uptake of the parasite. One of the most striking events in the parasite-heart muscle cells interaction is the disruption of the actin cytoskeleton. We have investigated the regulation of the actin mRNA during the cytopathology induced in myocardial cells by the parasite. T. cruzi invasion increases calcium resting levels in cardiomyocytes. We have previously shown that Ca2+ ATPase of the sarcoplasmic reticulum (SERCA) is involved in the invasion of T. cruzi in cardiomyocytes. Treating the cells with thapsigargin, a drug that binds to all SERCA ATPases and causes depletion of intracellular calcium stores, we found a 75% inhibition in the T. cruzi-cardiomyocytes invasion.     

Estimated financial impact of Trypanosoma vivax on the Brazilian pantanal and Bolivian lowlands

The financial impact of the first outbreak of Trypanosoma vivax in the Brazilian Pantanal wetland is estimated. Results are extended to include outbreaks in the Bolivian lowlands providing a notion of the potential influence of the disease and an analytical basis. More than 11 million head of cattle, valued at more than US$3 billion are found in the Brazilian Pantanal and Bolivian lowlands. The total estimated cost of the 1995 outbreak of T. vivax is the sum of the present values of mortality, abortion, and productivity losses and treatment costs, or about 4% of total brood cow value on affected ranches. Had the outbreak gone untreated, the estimated losses would have exceeded 17% of total brood cow value.     

Partial protection of mice against Trypanosoma cruzi after immunizing with the TcY 72 antigenic preparation

A 72 kDa Trypanosoma cruzi glycoprotein recognized by the 164C11 monoclonal antibody (IgM isotype) was purified by preparative electrophoresis. The antigenic preparation obtained, named TcY 72, was used to immunize C57Bl/10 mice. The following results were observed after immunization: (1) induction of higher titres of IgG than IgM antibodies, as evaluated by indirect immunofluorescence; (2) significant DTH after injection of epimastigotes in mice footpads; (3) peak parasitemia in immunized mice was significantly reduced and animals were negative by 13 days post-infection, although the mice still succumb to infection; (4) the phenotypic analysis of spleen cell populations showed a decrease in the CD4/CD8 ratio in immunized mice. Taken as a whole, these findings indicate that TcY 72 is immunogenic and potentially important for protective immunity.     

Identification of Cryptosporidium felis in a cow by morphologic and molecular methods

Apicomplexan Cryptosporidium parasites infect a wide range of vertebrate hosts. While some species are limited to a single host group, such as Cryptosporidium baileyi, which infects chickens, other species of this genus, such as C. parvum, infect a wide range of mammalian species from mice to humans. During an investigation of Cryptosporidium infection in cattle on a farm in northern Poland, we identified an infection caused by C. felis, in addition to known infections with C. muris and C. parvum. This new infection was identified based on the size of the oocysts (mean size, 4.3 +/- 0.4 micrometer; range, 3.5 to 5.0 micrometer), as well as by analysis of the molecular sequence of the variable region of the small-subunit rRNA. This finding demonstrates the complex host specificity and circulation in the environment of Cryptosporidium species.     

Nonlinear system identification using a neo fuzzy neuron algorithm: electrical drive application

This work presents a Neo-Fuzzy-Neuron algorithm for the identification of nonlinear dynamic systems at the point of view of a rotor flux observer. The algorithm training is on-line, has low computational cost, does not require previous training and its convergence in one step is proved. The gradient descent method is used for its weights adjustment. Simulation and experimental results demonstrate the effectiveness of the algorithm for flux observer of induction motor drive system.     

NBD-cholesterol incorporation by rat macrophages and lymphocytes: a process dependent on the activation state of the cells

The time-course of incorporation of NBD-cholesterol by macrophages (Ma) and lymphocytes (LY) obtained from untreated and thioglycollate-injected (thio) rats was investigated. NBD-cholesterol incorporation was also examined in Ma obtained from untreated rats and stimulated in vitro by lipopolysaccharide (LPS) and phorbol-myristate acetate (PMA). The same measurement was performed in LY from untreated rats stimulated by addition of LPS and concanavalin A (Con A) into the culture medium. Thio-treated Ma showed high fluorescence intensity after 1 h of incubation with NBD-cholesterol. Ma submitted concomitant to LPS and NBD-cholesterol showed low fluorescence intensity, as well as Ma stimulated with PMA. Ma from untreated and LPS pre-treated rats showed a similar time-course of incorporation. LY from thio-treated rats showed lower incorporation of NBD-cholesterol in comparison to LY from untreated rats. Incorporation was reduced when LPS was added concomitantly with NBD-cholesterol. On the other hand, LY pre-treated with LPS for 48 h showed a very high incorporation of NBD-cholesterol. Con A treatment did not cause a significant effect on NBD-cholesterol incorporation. The findings presented herein led us to conclude that the uptake of NBD-cholesterol by Ma and LY is markedly affected by the activation state of the cells.     

Three-dimensional structure of an unusual Kunitz (STI) type trypsin inhibitor from Copaifera langsdorffii

The crystallographic structure of a novel trypsin inhibitor (CTI) from Copaifera langsdorffii is reported. The structure was solved by MIRAS procedure and refined to a crystallographic residual of 17.3% (R(free) = 20.3%) at 1.8 A resolution. Two isomorphous derivatives were obtained by quick cryo-soaking approach. CTI is the first structure of a member of Kunitz (STI) family formed by two noncovalently bound polypeptide chains and only one disulfide bridge. A standard Kunitz-type inhibitor has a single polypeptide chain and two disulfide bridges. Structural features granting CTI high inhibitory activity are discussed.