DEFAR - Artigos publicados em periódicos

URI permanente para esta coleçãohttp://www.hml.repositorio.ufop.br/handle/123456789/531

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1988 - 198911990 - 199925

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Data final: 1999

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    Interactions between a macrophage cell line (J774A1) and surface-modified poly(D, L-lactide) nanocapsules bearing poly(ethylene glycol).
    (1999) Mosqueira, Vanessa Carla Furtado; Legrand, Philippe; Gref, Ruxandra; Heurtault, Béatrice; Appel, M.; Barratt, Gillian
    The interactions of naked and surface-modified poly(D,L-lactic acid) (PLA) nanocapsules (NC), where polyethyleneglycol (PEG) was adsorbed or covalently attached, have been studied with a macrophage-like cell line. The fluorescent oil marker, DiD, was successfully encapsulated in NCs in order to follow their interactions with cells. The cell-associated fluorescence obtained with PEG-PLA NC was about 3- to 13-fold lower than that obtained with naked-PLA NC. The effects of PEG chain length, its content as a percentage of total polymer and NC concentration in the culture medium were evaluated. PEG-PLA NC showed dramatically reduced fluorescence association with cells during an 18 h incubation compared with naked-PLA NC, showing that covalent attachment of PEG is important for the persistence of low uptake. The best results in reducing cell-associated fluorescence were obtained with a surface-modified PEG-PLA NC bearing a chain with 20000 MW. Increasing the percentage of PEG produced a reduction in marker association for a given PEG chain length. Moreover, when the PEG-containing poloxamer was simply adsorbed, marker association was dependent on the extent of dilution and the type of serum in the culture medium. Serum proteins, especially immunoglobulins, increased cell-associated fluorescence for PEG-adsorbed NC, but had very little effect on PEG-PLA NC. Marker association was only partially inhibited in the presence of cytochalasin B. The mechanisms of cell-NC interaction depended on the characteristics of the NC surface in each formulation. When the NC was physically separated from cells no diffusion of fluorescent marker in aqueous medium occurred. Nevertheless, collision-mediated transfer of DiD from NC to J774 cells was a non-negligible route of marker transfer, mainly for naked NC. However, this collision-mediated transfer was reduced for the PEG-PLA NC probably due to the restricted contact between NC and cells afforded by PEG steric hindrance at the surface.
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    Maillard reaction during the processing of "Doce de Leite".
    (1994) Pavlovic, Suzana; Santos, Rinaldo Cardoso dos; Glória, Maria Beatriz Abreu
    ‘Doce de leite’, a dairy product widely consumed in Brazil as a dessert or cake filling, is obtained from the heat treatment of milk and sucrose. On heating, the Maillard reaction occurs with the formation of desirable browncoloured products with a characteristic and pleasant flavour. However, the reaction can also lead to changes in nutritive value. In order to follow chemically the extension of the Maillard reaction and its effect on the nutritive value of ‘doce de leite’ its commercial processing was followed. Increases in the level of free 5-hydroxymethylfurfural and in absorption at 420 nm by pigments attached to the protein were observed. The amino acid analysis showed a significant decrease in lysine levels (33%) as well as in arginine (11%) and histidine (10%). There was also a reduction in available lysine levels, as measured by the fluorodinitrobenzene (50.6%) and by the 2,4,6-trinitrobenzenesulphonic acid (23.5%) methods. These results suggest a deleterious effect of the processing of ‘doce de leite’ on the nutritive value of the milk.
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    IL-10 plays a role in modulation of human granulomatous hypersensitivity against Schistosoma mansoni eggs induced by immune complexes.
    (1997) Rezende, Simone Aparecida; Teixeira, David Nascimento Silva; Drummond, Sandra Costa; Goes, Alfredo Miranda de
    It has been demonstrated that the chronic intestinal form of schistosomiasis is associated with the establishment and maintenance of a variety of immunoregulatory mechanisms that lead to a diminished granulomatous reaction to parasite eggs. Using an in vitro model of granuloma reaction we showed that immune complexes (IC) isolated from the sera of chronic intestinal schistosomiasis patients were able to reduce the granulomatous hypersensitivity (developed by peripheral blood mononuclear cells (PBMC) from schistosomiasis patients) to soluble egg antigen (SEA)-conjugated polyacrylamide beads (PB–SEA). This inhibitory activity, mediated by IC, was also observed in the proliferative response of PBMC stimulated with SEA and soluble worm antigen preparation (SWAP). Furthermore, we observed a decrease in TNF-α and an increase in IL-10 production by PBMC treated with IC in an in vitro granuloma reaction. This phenomenon was also seen in a cell proliferation assay when PBMC were treated with IC and stimulated with S. mansoni antigens. These results demonstrate that circulating IC may down-regulate PBMC reactivity to S. mansoni antigens by changing the cytokine pattern produced by these cells.
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    Heart autonomic innervation during the acute phase of the experimental American trypanosomiasis in the dog.
    (1998) Machado, Conceição Ribeiro da Silva; Caliari, Marcelo Vidigal; Lana, Marta de; Tafuri, Washington Luiz
    Heart autonomic innervation was studied in dogs during the acute phase of the experimental infection with the Berenice-78 strain of Trypanosoma cruzi. A glyoxylic acid–induced fluorescence method for catecholamines and a thiocholine method for demonstrating acetylcholinesterase activity showed the sympathetic and the parasympathetic nerve fibers, respectively. At day 34 of infection, moderate-to-intense rarefaction of both cholinergic and noradrenergic nerve fibers occurred in the atria of all animals coincident with moderate to intense myocarditis. In the ventricles, sympathetic denervation was clearly present only when the inflammatory processes were moderate to intense. Preliminary results on the chronic phase indicate that normal autonomic innervation coexists with an incipient chronic fibrosing myocarditis.
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    Granulomatous hypersensitivity to Schistosoma mansoni egg antigens in human schistosomiasis. IV. A role for prostaglandin-induced inhibition of in vitro granuloma formation.
    (1994) Goes, Alfredo Miranda de; Rezende, Simone Aparecida; Gazzinelli, Giovanni; Doughty, Barbara L.
    The prostaglandins (PG) are known to regulate immune cell function (s) and participate in the progression of both acute and chronic inflammatory reactions. Using an in vitro model of Schistosoma mansoni egg-induced hypersensitivity granulomas, we have delineated the role of immune complexes (IC) in the induction andrelease of PG and their inhibitory effects on granuloma development. The hypersensitivity- type granuloma reaction to soluble egg antigen (SEA) was examined using a model of in vitro granuloma ,formation. Our results show that granuloma formation was dramatically suppressed by the addition to the granuloma cultures of IC, PGE,, PGE2, while PGF, alpha had no significant effect. The inhibition of the PG function was achieved by the introduction of anti-PG antibodies that blocked suppression of granuloma,formation. It appears in this model system that IC may inhibit the activity of granuloma formation by stimulating the monocyte-macrophage lineage to release inhibitory mediators. Our results suggest that the prostaglandins E series may be important in the generation and maintenance of suppression of the granulomatous inflammatory response to S. mansoni egg antigens .
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    Compared vectorial transmissibility of pure and mixed clonal genotypes of Trypanosoma cruzi in Triatoma infestans.
    (1998) Pinto, Artur da Silveira; Lana, Marta de; Bastrenta, Brigitte; Barnabé, Christian; Quesney, Virginie; Noel, Sébastien; Tibayrenc, Michel
    A total of 15 mixtures involving 9 di erent stocks attributed to the 19/20, 32 and 39 major clonal genotypes of Trypanosoma cruzi were used to infect third-instar nymphs of Triatoma infestans via an arti®- cial feeding device. Three biological parameters were considered: (1) the percentage of infected insects (%II), (2) the number of ¯agellates per insect (NFI), and (3) the percentage of trypomastigotes per insect (%DIF). Ge- netic characterization by both multilocus enzyme elec- trophoresis (MLEE) and random ampli®cation of polymorphic DNA (RAPD) indicated that in almost all cases (87%), mixtures remained present after completion of the whole cycle in the insect vector. Two lines of comparison were performed: (1) pure clonal genotypes versus corresponding mixed clonal genotypes and (2) the actual behavior of mixed clonal genotypes versus the expected behavior of the theoretical mixture (i.e. the arithmetic mean of the results observed for each of the two clonal genotypes taken separately). Statistical analyses of the variables were made di cult because of the presence of large standard deviations. Nevertheless, in several cases, mixtures di ered signi®cantly from pure clonal genotypes, and in one case the actual mixture di ered signi®cantly from the theoretical mixture. In some cases, interaction (either potentialization or re- ciprocal inhibition) could be suspected.
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    Characterization of two isolates of Trypanosoma cruzi obtained from the patient Berenice, the first human case of Chagas disease.
    (1996) Lana, Marta de; Chiari, Cléa de Andrade; Chiari, Egler; Morel, Carlos Medicis; Gonçalves, Antônio M.; Romanha, Alvaro José
    Two isolates of Trypanosoma cruzi were obtained from the patient Berenice, the first human case of Chagas’ disease (Chagas 1909), when she was 55 and 71 years old, respectively. The isolates were characterized on the basis of their epimastigote-trypomastigote differentiation in liquid media and of the electrophoretic pattern of EcoR1 digestion products of kinetoplast DNA (k- DNA) minicircles (schizodeme) and isoenzyme patterns (zymodeme). Clear differences were found between the isolates, suggesting the occurrence of a heterogeneous population of T. cruzi in the infection of this patient.
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    Cell surface analysis of trypanosomes of the subgenus Schizotrypanum isolate from bats.
    (1996) Pinto, Artur da Silveira; Teixeira, Luiz Fernando de Medeiros; Padron, Thais Cristina Baeta Soares Souto; Andrade, Arnaldo Feitosa Braga de
    Two stocks (M5, M29) of trypanosomes of the subgenus Schizotrypanum were isolated from the bat Phylloslomus hastatus and analyzed for cell electrophoretic mobility (EPM) and lectin binding surface sites. Epimastigotes from the M5 and M29 stocks presented a mean EPM of around - 0.57 and -0.56 μm, s-1.V-1.cm, respectively. Differences in the agglutination profiles were detected between epimastigotes or trypomastigotes from the two parasite populations using lectins with specificity for D-GlcNAc, D-GalNAc, D-Gal and D-Man as probe. Major variation was observed between epimastigote forms. Additionally, the D-GlcNAc binding lectins WGA and BS II strongly interacted with the trypomastigote from both M5 and M29 stocks; this fact is evidence that these trypanosomes are distinct from Trypanosoma (Schizotrypanum) cruzi.
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    Regulation of sugar transport systems in Fusarium oxysporum var. lini.
    (1990) Brandão, Rogélio Lopes; Dias, Maria da Conceição Loureiro
    Fusarium oxysporum var. Iini (ATCC 10960) formed a facilitated diffusion system for glucose (Ks, about 10 mM) when grown under repressed conditions. Under conditions of derepression, the same system was present together with a high-affinity (K5, about 40 ,iM) active system. The maximum velocity of the latter was about 5% of that of the facilitated diffusion system. The high-affinity system was under the control of glucose repression and glucose inactivation. When lactose was the only carbon source in the medium, a facilitated diffusion system for lactose was found (Ks, about 30 mM).
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    Molecular cloning of a gene involved in glucose sensing in the yeast Saccharomyces cerevisiae.
    (1993) Aelst, Linda Van; Hohmann, Stefan; Bulaya, Botchaka; Koning, Wim de; Sierkstra, Laurens; Neves, Maria José; Luyten, Kattie; Alijo, Rafael; Ramos, José; Coccetti, Paola; Martegani, Enzo; Rocha, Neuza Maria de Magalhaes; Brandão, Rogélio Lopes; Dijck, Patrick Van; Vanhalewyn, Mieke; Durnez, Peter; Jans, Arnold W. H; Thevelein, Johan Maria
    Cells of the yeast Saccharomyces cerevisiae display a wide range of glucose-induced regulatory phenomena, including glucose-induced activation of the RAS-adenylate cyclase pathway and phosphatidylinosrtot turnover, rapid post-translatronal effects on the activity of different enzymes as well as long-term effects at the transcriptional level. A gene called GGS1 (for general Glucose Sensor) that is apparently required for the glucose-induced regulatory effects and several ggsi aHeles (fic/pf, bypi and cifi) has been cloned and characterized. A GGS1 homologue is present in Methanobacterium thermoautotrophicum. Yeast ggsi mutants are unable to grow on glucose or Received 25 November, 1992; revised and accepted 15 February, 1993. •For correspondence. Tel. (16) 220931; Fax (16) 204415. tThese two authors contributed equally to this paper. related readily fermentable sugars, apparently owing to unrestricted influx of sugar Into glycolysis, resulting in its rapid deregulation. Levels of intracellular free glucose and metabolites measured over a period of a few minutes after addition of glucose to cells of a ggsi^ strain are consistent with our previous suggestion of a functional interaction between a sugar transporter, a sugar kinase and the GGS1 gene product. Such a glucose-sensing system might both restrict the influx of glucose and activate several signal transduction pathways, leading to the wide range of glucose-induced regulatory phenomena. Deregulation of these pathways in ggsi mutants might explain phenotypic defects observed in the absence of glucose, e.g. the inability of ggsi diploids to sporulate.