Increased association of Trypanosoma cruzi with sialoadhesin positive mice macrophages

Trypanosoma cruzi is a parasite with large amounts of sialic acid (SA) residues exposed at its surface that seems to be involved in macrophages infection. Some macrophages, present in T. cruzi infected tissues, expresses sialoadhesin (Sn), a receptor that recognizes SA. Thus, the involvement of Sn in the association of T. cruzi to macrophages was investigated. Sn was induced in mice peritoneal macrophages by homologous serum (HS) cultivation. Epimastigotes and trypomastigotes associated more to HS cultured macrophages than to fetal bovine serum (FBS). Blocking of Sn with antibodies reduced the association of trypomastigotes to similar level as for FBS cultured macrophages. Desialylation reduced the association of parasites to HS cultured macrophages indicating the Sn importance. Furthermore, the entrance mechanism of trypomastigotes to Sn positive macrophages has a phagocytic nature as demonstrated by scanning electron microscopy and cytochalasin D treatment. Sn positive macrophages may important in the initial trypomastigote infection, thus in the establishment of Chagas disease.

Morphological changes during conoid extrusion in Toxoplasma gondii tachyzoites treated with calcium ionophore

Treatment of tachyzoites of Toxoplasma gondii with the calcium ionophore A23187 induced dramatic ultrastructural changes that were observed by light and electron microscopy. Light microscopy showed a higher percentage (22%) of tachyzoites with the conoid extruded when compared to control parasites. Electron microscopy confirmed the conoid extrusion by both transmission and scanning electron microscopy. Freeze-fracture replicas showed that the plasma membrane adjacent to cytoplasmic dense granules appeared devoid of intramembranous particles. Membrane-limited vesicles and filopodium-like structures at the cell surface were observed in treated cells. 3-D reconstruction from serial sections confirmed the data and showed a heterogeneity in dense granule shape not reported in control cells.

[The trajectory of the Brazilian Nurses Association-Alagoas]

This article outlines the trajectory of the Brazilian Association of Nursing (ABEn) in Alagoas and its influence in the organization of the nursing profession in this federal state. It points out that ABEn-AL was the first institution to organize nursing in Alagoas, since it was founded prior to any nursing graduation course or even any nursing syndicate. Therefore, ABEn is considered a decisive landmark in the political and professional organization of nursing in the state of Alagoas.

Host cell surface sialic acid residues are involved on the process of penetration of Toxoplasma gondii into mammalian cells

Tachyzoites of Toxoplasma gondii are able to infect several cell types tested (wild-type chinese hamster ovary (CHO) cells and glycosylation mutants, Vero and LLCMK2 cells). However, the extent of infection varied. Mutant cells which present few or no surface-exposed sialic acid residues were infected to a lower extent. Similar results were obtained if sialic acid residues were removed by previous neuraminidase treatment. Addition of sialic acid residues to surface-exposed glycoconjugates using fetuin as a sialic acid donor and the trans-sialidase of Trypanosoma cruzi rendered the cells more easily infected by Toxoplasma gondii. These observations indicate that surface-exposed carbohydrate residues of the host cell are involved on the process of Toxoplasma gondii-host cell recognition.