Biomedical subjects

B P Dias Filho

Publications and source records attributed to B P Dias Filho.

12 recordsLinked to original sources

PubMed2006

Antibacterial activity of indole alkaloids from Aspidosperma ramiflorum.

We evaluated the antibacterial activities of the crude methanol extract, fractions (I-V) obtained after acid-base extraction and pure compounds from the stem bark of Aspidosperma ramiflorum. The minimum inhibitory concentration (MIC) was determined by the microdilution technique in Mueller-Hinton broth. Inoculates were prepared in this medium from 24-h broth cultures of bacteria (10(7) CFU/mL). Microtiter plates were incubated at 37 masculineC and the MICs were recorded after 24 h of incubation. Two susceptibility endpoints were recorded for each isolate. The crude methanol extract presented moderate activity against the Gram-positive bacteria B. subtilis (MIC = 250 microg/mL) and S. aureus (MIC = 500 microg/mL), and was inactive against the Gram-negative bacteria E. coli and P. aeruginosa (MIC > 1000 microg/mL). Fractions I and II were inactive against standard strains at concentrations of < or =1000 microg/mL and fraction III displayed moderate antibacterial activity against B. subtilis (MIC = 500 microg/mL) and S. aureus (MIC = 250 microg/mL). Fraction IV showed high activity against B. subtilis and S. aureus (MIC = 15.6 microg/mL) and moderate activity against E. coli and P. aeruginosa (MIC = 250 microg/mL). Fraction V presented high activity against B. subtilis (MIC = 15.6 microg/mL) and S. aureus (MIC = 31.3 microg/mL) and was inactive against Gram-negative bacteria (MIC > 1000 microg/mL). Fractions III, IV and V were then submitted to bioassay-guided fractionation by silica gel column chromatography, yielding individual purified ramiflorines A and B. Both ramiflorines showed significant activity against S. aureus (MIC = 25 microg/mL) and E. faecalis (MIC = 50 microg/mL), with EC50 of 8 and 2.5 microg/mL for ramiflorines A and B, respectively, against S. aureus. These results are promising, showing that these compounds are biologically active against Gram-positive bacteria.

Anti-Bacterial Agents↗

PubMed2002

Bacterial population of a two-phase anaerobic digestion process treating effluent of cassava starch factory.

Different groups of microorganisms in a two-phase anaerobic system were enumerated to evaluate the prevalence of specific groups and species. Total and fecal coliforms showed similar values both in acidogenic and methanogenic reactors. The fecal streptococci were 4-fold higher in the acidogenic reactor, when compared with those of the methanogenic reactor. As expected, no methane forming or sulfate reducing bacteria were found in the acidogenic reactor. The populations of methanogenic bacteria were dominated by a mixed population of straight to curved rods and multicellular filaments which strongly resembled members of the genus Methanosaeta. Seven prevalent species of facultative anaerobic gram-negative bacteria were identified as Previdencia alcalifacienciens, Providencia rettgeri, Enterobacter cloaceae, Citrobacter freundii, Klebsiella oxytoca, Proteus pennri and Yersinia enterocolitica. The species Pseudomonas aeruginosa, Stentophomonas maltophila and Acinotobacter iwoffi, were the most frequently isolated glucose non-fermenting gram-negative bacilli. Among these species, only P. aeruginosa was present in high number in each sample.

Bacteria, Anaerobic↗

PubMed2001

Surface component characterization as taxonomic tools for Phytomonas spp identification.

The genus Phytomonas arbitrarily includes all protozoa of the family Trypanosomatidae isolated from plants, but its differentiation is a complex task. The phase separation technique using Triton X-114 was used to analyze hydrophobic and hydrophilic surface proteins in ten strains of Phytomonas isolated from various fruits. The iodination of surface proteins by the Iodo-Gen method was also used for Phytomonas isolates from tomatoes, corn and annatto, Herpetomonas samuelpessoai and Crithidia fasciculata. The distribution of protein-bound radioactivity in acrylamide gels was determined by autoradiograms and showed the presence of protein bands of 36-68 kDa in all strains of Phytomonas: there were two major bands at 88 kDa and 94 kDa, with minor bands at 36 kDa and 142 kDa in H. samuelpessoai; and there were three bands at 74, 86 and 94 kDa, with minor bands at 23 kDa and 105 kDa in C. fasciculata. The results demonstrated that samples of plant parasites can be clearly differentiated from H. samuelpessoai and C. fasciculata. These plant parasites were also submitted to polysaccharide analysis by gas-liquid chromatography of the corresponding alditol acetate. Arabinose, galactose, glucose and mannose, were the major monosaccharides found, while fucose, rhamnose and xylose were found in smaller amounts. The results of all these methods indicated that, after extension to a wider range of trypanosomatid strains, they may be useful in Phytomonas taxonomy.

Animals↗

PubMed2001

Microbial populations of an upflow anaerobic sludge blanket reactor treating wastewater from a gelatin industry.

The microbial populations of an upflow anaerobic sludge blanket reactor, used for treating wastewater from the gelatin industry, were studied by microbiological methods and phase-contrast and electron microscopy. Microscopy examination of the sludge showed a complex mixture of various rod-shaped and coccoid bacterial pluslong filaments and verymobile curved rods. In addition free-living anaerobic ciliates and flagellates were also observed. The trophic group population observed in decreasing order of dominance were hydrolytic and acetogenic at 10(6) and sulfate reducing and methanogenic at 10(5). The rate of methane production in anaerobic granular sludge cultivated in growth medium supplement with formate pressurized with H2:CO2 showed a significant increase in methane yield compared with theseed culture containingthe same substrate and atmosphere of N2:CO2. Similar rates of methane production were observed when the growth medium was supplemented with acetate pressurized either with H2:CO2 or N2:CO2. The number of total anaerobic bacteria at 10(7), fecal coliforms and total coliforms at 10(6), and fecal streptococci at 10(3) is based on colony counts on solid media. The four prevalent species of facultative anaerobic gram-negative bacteria that belong to the family of Enterobacteriaceae were identified as Escherichia coli, Esherichia fergusonii, Klebsiella oxytoca, and Citrobacter freundii. The species Aeromonas hydrophila, Aeromonas veronii, Acinetobacter iwoffi and Stenotrophomonas maltophila were the most frequently isolated glucose fermenting and nonfermenting gram-negative bacilli.

Anaerobiosis↗

PubMed1999

Purification and partial characterization of N-acetyl-beta-D-glucosaminidase from Tritrichomonas foetus.

Cells of Tritrichomonas foetus were suspended in buffer (0.1 M phosphate, 0.15 M NaCl, pH 7), sonicated for 2 min on ice, and centrifuged at low speed (500 g/40 min) at 4 degrees C. The resulting supernatant was centrifuged at 100,000 g for 30 min at 4 degrees C. The N-acetyl-beta-D-glucosaminidase activity as assayed by fluorimetric assay using 4-methylumbelliferil beta-D-N-acetylglucosamine (4MU-GlcNAc) was found predominantly (> 95%) in the supernatant. Isolation of the enzyme was achieved by a combination of gel filtration with ion-exchange chromatography. Non-denaturing gel electrophoresis indicated that N-acetyl-beta-D-glucosaminidase activity was present in two bands. When the two fluorescent bands were excised from the non-denaturing gel and rerun on denaturing 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis they exhibited two proteins with molecular masses of 40 and 45 kDa. The pH optimum is approximately 7.5 and the temperature optimum is approximately 37 degrees C.

Acetylglucosaminidase↗

PubMed1999

Identification and localization of an adhesin on the surface of Tritrichomonas foetus.

Tritrichomonas foetus is a mucosal parasite of the urogenital-vaginal tract of cattle that strongly adheres to erythrocytes, which suggests that it presents an adhesin that recognizes red blood cells from different animal species and blood groups. In the present report we describe a cell-fractionation method for obtainment of a membrane fraction of T. foetus, which adhered to red blood cells. The T. foetus adhesin was obtained after parasite lysis and fractionation followed by ultracentrifugation, whereby a 100,000-g pellet fraction showed a strong hemagglutinating activity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of this fraction, of erythrocyte ghosts, and of ghosts allowed to interact with the parasite membrane fraction revealed the presence of a 100-kDa protein as the putative adhesin. Polyclonal antibodies obtained in rabbits immunized with this protein recognized proteins of 100 and 90 kDa as determined by immunoblotting. Confocal laser scanning microscopy and transmission electron microscopy of cells incubated first in the presence of the antibody and subsequently in the presence of fluorescein- or gold-labeled goat anti-rabbit IgG showed labeling of the protozoan surface as well as of some cytoplasmic vesicles.

Animals↗

PubMed1999

Purification and immunocytochemical localization of neuraminidase from Tritrichomonas foetus.

Lysis of Tritrichomonas foetus with a solution of the non-ionic detergent Triton X-114 at 0 degree C, followed by low-speed centrifugation, resulted in a detergent-insoluble pellet and a detergent-soluble supernatant. The supernatant was further fractionated by phase separation at 30 degrees C into a detergent-rich phase and an aqueous phase. Neuraminidase activity was mostly located in the detergent-insoluble pellet. When the parasites were incubated with bacterial phosphatidylinositol phospholipase C (PI-PLC) prior to detergent solubilization and phase separation neuraminidase activity was predominantly recovered in aqueous phase, rather than in the pellet and detergent phase. The molecular mass determined by gel permeation in high performance liquid chromatography (HPLC) and SDS-PAGE was 80,000 Da. Indirect immunofluorescence microscopy using polyclonal antibodies raised in rabbits against the purified neuraminidase, indicated that the enzyme is exposed on the cell surface. Previous treatment of the cells with PI-PLC significantly reduced antibody binding. Incubation of cryo-sections with the antibodies followed by detection using gold-labelled anti-rabbit IgG confirmed the presence of neuraminidase in the plasma membrane enclosing the cell body and flagella and in the membrane of vesicles preferentially located at the peripheral region of the protozoan.

Animals↗

PubMed1996

Structural changes at the site of Tritrichomonas foetus-erythrocyte interaction.

Tritrichomonas foetus strongly agglutinates human erythrocytes, thus suggesting the occurrence of an adhesin associated with its surface. Adherence was observed immediately after mixing of the parasites with erythrocytes and the intensity increased for up to 30 min. Scanning electron microscopy examination of T. foetus-erythrocytes attachment showed that trichomonad cytoadherence took place mainly through their anterior and recurrent flagella. Ultrastructural observations showed that T. foetus contacts human red blood cells through punctual binding, inducing the separation between the two lipid monolayers of the parasite plasma membrane. This structural modification was also seen in freeze-fracture replicas where protrusions on the P and depressions on the E fracture faces were observed. No intramembranous particles, which mainly correspond to membrane integral proteins, were observed at the adhesion areas, indicating lateral mobility of integral membrane components involved in the appearance of the intramembranous particles. However, no changes was observed on the surface coat.

Animals↗

PubMed1995

Phospholipase C-mediated release of neuraminidase from Tritrichomonas foetus cell surface.

The release of the Tritrichomonas foetus plasma-membrane ectoenzyme neuraminidase by exogenous specific phospholipase C (PI-PLC) was investigated. Neuraminidase activity was determined using both the peanut agglutinin (PNA) hemagglutination test and the specific substrate N-acetylneuramin-lactose in a colorimetric assay. The release of the neuraminidase by PI-PLC was dependent on the reaction time and the concentration of PI-PLC. Neuraminidase activity was also detected in supernatant of untreated T. foetus. Spontaneous or PI-PLC-induced release of neuraminidase from protozoan cells was markedly decreased by 10 mM ZnCl2, suggesting the occurrence of an endogenous PI-PLC in the parasite. After T. foetus lysis at 37 degrees C with a solution of Triton X-114, neuraminidase activity was preferentially found in the aqueous phase rather than in the detergent phase, again suggesting that the parasite contains an endogenous PI-PLC that converts the hydrophobic form of neuraminidase anchored to the T. foetus cell membrane into a hydrophilic form. These results show that neuraminidase is linked to the T. foetus plasma membrane via a glycosylphosphatidylinositol anchor.

Animals↗

PubMed1992

Cell surface saccharide differences in drug-susceptible and drug-resistant strains of Trichomonas vaginalis.

Surface carbohydrates of drug-resistant and drug-susceptible strains of Trichomonas vaginalis were analysed using lectins. The presence of D-GalNAc, D-Gal and mannose-like residues was detected in T. vaginalis. Marked differences in exposed surface carbohydrates were documented, e.g. wheat germ agglutinin (WGA) selectively agglutinated the drug-susceptible strain whereas drug-resistant parasites reacted preferentially with concanavalin A (Con A). In drug-resistant, but not in drug-susceptible strains, trypsinization induced the appearance of soybean agglutinin. Binding studies using fluorescein-labelled WGA and Con A essentially confirmed the agglutination experiments. Both the intense cell agglutination and the fluorescent WGA-binding displayed by a drug-susceptible strain, were completely nullified by neuraminidase treatment, suggesting the presence of an exposed sialic acid moiety on the T. vaginalis surface.

Agglutination Tests↗

PubMed1988

Polysaccharide and glycolipid composition in Tritrichomonas foetus.

1. The polysaccharide and glycolipid composition in Tritrichomonas foetus was studied by paper, thin-layer and gas-liquid chromatographic analysis. 2. The carbohydrate components of the polysaccharide were glucose (47%), galactose (34%) and mannose (19%). N-acetylneuraminic acid was the sialic acid derivative characterized in the flagellate whole cells. 3. The sialic acid density was estimated as 2.7 x 10(7) residues/cell. 4. The long-chain base dihydrosphingosine, the carbohydrates galactose (67%), glucose (21%) and mannose (12%) as well as the fatty acids myristic (48%) and palmitic (52%) acids were characterized as components of the total glycolipids of T. foetus. 5. Total glycolipids were fractionated: a galactocerebroside and a ganglioside were identified.

Animals↗

PubMedDate not supplied

Antibacterial activity of Ocimum gratissimum L. essential oil.

The essential oil (EO) of Ocimum gratissimum inhibited Staphylococcus aureus at a concentration of 0.75 mg/ml. The minimal inhibitory concentrations (MICs) for Shigella flexineri, Salmonella enteritidis, Escherichia coli, Klebsiella sp., and Proteus mirabilis were at concentrations ranging from 3 to 12 microg/ml. The endpoint was not reached for Pseudomonas aeruginosa (>=24 mg/ml). The MICs of the reference drugs used in this study were similar to those presented in other reports. The minimum bactericidal concentration of EO was within a twofold dilution of the MIC for this organism. The compound that showed antibacterial activity in the EO of O. gratissimum was identified as eugenol and structural findings were further supported by gas chromatography/mass spectra retention time data. The structure was supported by spectroscopic methods.

Enterobacteriaceae↗