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P M Araújo

Publications and source records attributed to P M Araújo.

6 recordsLinked to original sources
PubMed2004

Sulfated fucan as support for antibiotic immobilization.

Xylofucoglucuronan from Spatoglossum schröederi algae was tested as a support for antibiotic immobilization. The polysaccharide (20 mg in 6 ml) was first activated using carbodiimide, 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide methiodide (20 mg in 2 ml), under stirring for 1 h at 25 masculine C and pH from 4.5 to 5.0. After adjusting the pH to 8.0, either gentamicin or amikacin (62.5 mg in 1.25 ml) was then immobilized on this chemically modified polysaccharide with shaking for 24 h in a cold room. Infrared spectra of the activated carbodiimide xylofucoglucuronan showed two bands to carbonyl (C=O at 1647.9 and 1700.7 cm(-1)) and to amide (C-NH2) groups (1662.8 and 1714.0 cm(-1)). Microbial characterization of the derivatives was carried out by the disk diffusion method using Staphylococcus aureus or Klebsiella pneumoniae incorporated in Müller Hinton medium. Inhibition halos of bacterial growth were observed for the antibiotics immobilized on this sulfated heteropolysaccharide before and after dialysis. However, the halos resulting from the samples after dialysis were much smaller, suggesting that dialysis removed either non-covalently bound antibiotic or other small molecules. In contrast, bacterial growth was not inhibited by either xylofucoglucuronan or its activated form or by gentamicin or amikacin after dialysis. An additional experiment was carried out which demonstrated that the sulfated heteropolysaccharide was hydrolyzed by the microorganism. Therefore, the antibiotic immobilized on xylofucoglucuronan can be proposed as a controlled drug delivery system. Furthermore, this sulfated heteropolysaccharide can be extracted easily from sea algae Spatoglossum schröederi.

Amikacin↗
PubMed1997

Association between polyclonal B cell activation and the presence of autoantibodies in mice infected with Yersinia enterocolitica O:3.

Eight-week old conventional female Swiss mice were inoculated intravenously with Yersinia enterocolitica O:3. A second group of normal mice was used as control. Five mice from each group were bled by heart puncture and their spleens were removed for spleen cell collection on the 3rd, 5th, 7th, 10th, 14th and 21st day after infection. Immunoglobulin-secreting spleen cells were detected by the isotype-specific protein A plaque assay. Total immunoglobulin levels were determined in mouse serum by single radial immunodiffusion and the presence of autoantibodies was determined by ELISA. We observed a marked increase in the total number of cells secreting immunoglobulins of all isotypes as early as on the 3rd day post-infection and the peak of secretion occurred on the 7th day. At the peak of the immunoglobulin response, the total number of secreting cells was 19 times higher than that of control mice and most immunoglobulin-secreting cells were of the IgG2a isotype. On the 10th day post-infection, total serum immunoglobulin values were 2 times higher in infected animals when compared to the control group, and continued at this level up to the 21st day post-infection. Serum absorption with viable Y. enterocolitica cells had little effect on antibody levels detected by single radial immunodiffusion. Analysis of serum autoantibody levels revealed that Y. enterocolitica infection induced an increase of anti-myosin and anti-myelin immunoglobulins. The sera did not react with collagen. The present study demonstrates that Y. enterocolitica O:3 infection induces polyclonal activation of murine B cells which is correlated with the activation of some autoreactive lymphocyte clones.

Animals↗
PubMed1992

Anti-Trypanosoma-cruzi-proteinase antibodies and immunoprotection in experimental Chagas' disease.

To verify whether anti-Trypanosoma-cruzi-proteinase antibodies are able to play a role in the development of Chagas' disease, CBA/J and C57BL/6 mice were immunized with purified proteinase fractions: antibody production was studied and passive immunization experiments were carried out. No significant differences were observed in the titre, isotype composition and specificity of the antibodies produced by the mouse strains. Immune sera produced in one strain was able to protect mice of both strains, provided that the challenge did not exceed the number of parasites corresponding to 30-fold the LD50. The data presented suggest that anti-proteinase antibodies may play a role in immunoprotection.

Animals↗
PubMed1983

Trypanosoma cruzi: surface antigenic determinants.

A fraction (FAd) capable of inhibiting specific agglutination reactions of anti-epimastigote sera (anti-LE) was obtained by extracting the sediment of lyophilized epimastigote lysates (LE) with 0.05 M phosphate buffered saline, at 37 degrees C for 1 h. These conditions favored the action of parasite proteinase whose presence was detected by tandem-crossed immunoelectrophoresis experiments. As expected from the proteinase properties, the addition of 2-mercaptoethanol or sodium iodoacetate to the extracting solution resulted, respectively, in either increased or decreased amounts of protein in the resulting FAd. FAd components could be precipitated by the addition of Concanavalin A, methylated albumins or 0.1 N HCl. This fraction presented a single component when subjected to electrophoresis in 1% agarose gel with an electrophoretic mobility 1.2 times higher than that of human albumin. FAd component(s) were unable to penetrate 15% polycrylamide gel matrix unless 1% SDS was used. Under this condition four glycopeptide components, with Rm of 0.5, 0.55, 0.6 and 0.86, were detected. The antigenic determinants present in FAd resisted heating at 100 degrees C for 30 min and the prolonged action of pronase. However, these determinants were completely destroyed by the action of 25 mM sodium periodate, thus suggesting polysaccharide characteristics. Immunization of rabbits with FAd induced the production of antibodies that were unable to precipitate with either FAd or with parasite proteinase. These antibodies exhibited positive agglutination reactions with epimastigote forms and positive immunofluorescence and immunoperoxidase reactions with trypomastigote and amastigote forms of the different strains tested. FAd was able to inhibit these reactions as well as those obtained with anti-LE and anti-FA immune sera, whereas purified proteinase was unable to inhibit any of these reactions.

Animals↗
PubMed1981

Detection of a proteinase common to epimastigote, trypomastigote and amastigote of different strains of Trypanosoma cruzi.

Trypanosoma cruzi epimastigote lysates presented proteolytic activity both at pH 7.0 (Km = 2.5 mg casein/ml, Km = 12.2 mg hemoglobin/ml) and at pH 3.0 (Km = 2.5 mg hemoglobin/ml). A proteinase was isolated from these lysates by using three different steps: 1) Precipitation at -20 degrees C, pH 4.5, with 80% acetone; 2) Sephadex G200 chromatography and 3)Affinity chromatography on columns of Sepharose 4B coupled to p-aminophenylmercuri-acetate. The isolated proteinase, which is probably an SH-dependent enzyme, was able to hydrolyze hemoglobin at pH 3.0 and both casein and hemoglobin at pH 7., but was unable to hydrolyze the esterase synthetic substrate tested. A single enzyme of molecular weight 60,000 could be detected in purified preparations when analysed by disc gel electrophoresis, crossed immunoelectrophoresis, SDS-polyacrylamide gel electrophoresis and Sephadex chromatography. Antibodies induced by the purified proteinase, shown to be specific for proteinase molecules by line immunoelectrophoresis experiments, reacted with epimastigota of the Y strain and with trypomastigota and amastigota of five different strains tested. Electron microscopy observations of peroxidase labeled preparations indicated that the proteinase could be found at the surface of different forms of the parasite.

Animals↗