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L de Carvalho

Publications and source records attributed to L de Carvalho.

9 recordsLinked to original sources
PubMed1993

Effect of various digestive enzymes on the interaction of Toxoplasma gondii with macrophages.

The participation of resident, elicited, and activated macrophage surface components during internalization of tachyzoites of Toxoplasma gondii was analyzed using neuraminidase, phospholipase C, trypsin, protease, and hyaluronidase. Treatment of these macrophages with neuraminidase from Vibrio cholerae, phospholipase C from Bacillus cereus and Clostridium perfringens, protease, and hyaluronidase prior to their interaction with parasites increased the penetration of host cells by T. gondii. Incubation of macrophages with trypsin significantly inhibited the uptake of parasites. Our findings confirm previous observations that treatment of the macrophages with cytochalasin D under conditions that completely block the typical phagocytic process partially inhibits infection of the cells by T. gondii. The results of simultaneous treatment of the macrophages with enzymes and cytochalasin D suggested that the observed enhancement of cell infection by treatment with neuraminidase and hyaluronidase was attributable to a classic phagocytic process, whereas that obtained using phospholipase resulted from active penetration.

Animals↗
PubMed1991

Localization of lectin-binding sites and sugar-binding proteins in tachyzoites of Toxoplasma gondii.

Lectins and neoglycoproteins labeled with colloidal gold particles were used for the ultrastructural localization of carbohydrate residues and sugar-binding sites, respectively, in thin sections of tachyzoites of Toxoplasma gondii embedded in the Lowicryl K4M resin. Incubation of the sections in the presence of gold-labeled Canavalia ensiformis (Con A), Arachis hypogaea (PNA), Ricinus communis I (RCA I), Triticum vulgaris (WGA), and Limax flavus (LFA) agglutinins showed significant labeling of the rhoptries. However, no labeling of the parasite's surface was observed. Incubation of tachyzoites in the presence of gold-labeled albumin-N-acetyl-D-glucosamine or albumin-galactose, but not in the presence of albumin-mannose, led to labeling of the rhoptries in a pattern similar to that observed with the lectins. The results obtained are discussed in relation to the possible role played by secretion of rhoptry macromolecules during the process of T. gondii-host cell interaction.

Animals↗
PubMed1990

Internalization of surface anionic sites and phagosome-lysosome fusion during interaction of Toxoplasma gondii with macrophages.

The participation of cell surface anionic sites on the interaction between tachyzoites of Toxoplasma gondii and macrophages and the process of phagosome-lysosome fusion were analyzed using cationized ferritin as a marker of cell surface anionic sites and albumin-colloidal gold as a marker for secondary lysosomes. Incubation of either the macrophages or the parasites with cationized ferritin before the interaction increased the ingestion of parasites by macrophages. Anionic sites of the macrophage's surface, labeled with cationized ferritin before the interaction, were internalized together with untreated parasites. However, after interaction with glutaraldehyde-fixed or specific antibody-coated parasites, the cationized ferritin particles were observed in endocytic vacuoles which did not contain parasites. Macrophages previously labeled with albumin-gold at 37 degrees C, were incubated in the presence of cationized ferritin at 4 degrees C and then incubated with untreated or specific antibody-coated parasites. After interaction with opsonized parasites, the colloidal gold particles were observed in the parasitophorous vacuoles while the cationized ferritin particles were observed in cytoplasmic vesicles. However, when the interaction was carried out with untreated parasites, the parasitophorous vacuoles exhibited ferritin particles while the colloidal gold particles were observed in cytoplasmic vesicles. These observations, in association with studies previously reported, suggest that the state of the parasite surface determines the mechanism of parasite entry into the macrophage, the composition of the membrane lining the parasitophorous vacuole and the ability of lysosomes to fuse with the vacuoles.

Albumins↗
PubMedDate not supplied

Cytochemical localization of plasma membrane enzyme markers during interiorization of tachyzoites of Toxoplasma gondii by macrophages.

The enzyme activity of Mg++-ATPase, Na+-K+-ATPase, 5'-nucleotidase and NAD(P)H-oxidase was cytochemically detected at the ultrastructural level in mouse peritoneal macrophages infected with untreated and with specific antibody-coated Toxoplasma gondii tachyzoites. The Mg++-ATPase and 5'-nucleotidase were distributed throughout the macrophages' plasma membrane but were not observed in the membrane lining endocytic vacuoles containing ingested parasites; however, Na+-K+-ATPase activity was detected in the macrophages' plasma membrane as well as in the parasitophorous vacuoles that contained untreated or specific antibody-coated parasites. Reaction product, indicative of NAD(P)H-oxidase, was detected in the parasitophorous vacuoles that contained only specific antibody-coated parasites.

5'-Nucleotidase↗
PubMedDate not supplied

[Importance of serum albumin values in nutritional assessment and inflammatory activity in patients with Crohn's disease].

BACKGROUND: The serum albumin concentration has frequently been regarded as an indicator of nutritional status, although the hypoalbuminemia may reflect an acute phase protein response during inflammation mediated by cytokines. Both hypoalbuminemia and malnutrition are observed in Crohn's disease. OBJECTIVES: To correlate the serum albumin values to disease activity and also to nutritional status in patients with Crohn's disease. PATIENTS/METHODS: Thirty six patients were studied. Nutritional status was assessed by anthropometry measures and inflammatory activity determined by Harvey's simple clinical index and erythrocyte sedimentation rate. RESULTS: No correlation was found between malnutrition and hypoalbuminemia. The serum albumin levels correlated inversely with the disease activity. Hypoalbuminemia was 100% sensitive for detection of disease activity. CONCLUSION: This study suggests that serum albumin concentration is a very sensitive marker of inflammatory activity and not good indicator of the nutritional status in Crohn's disease. It is necessary a suitable laboratorial parameter for routine nutrition assessment in patients with this inflammatory bowel disease.

Adult↗