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Biomedical subjects

G A Pereira

Publications and source records attributed to G A Pereira.

8 recordsLinked to original sources
PubMed2001

Cytosolic thioredoxin peroxidase I is essential for the antioxidant defense of yeast with dysfunctional mitochondria.

The specific role of cytosolic thioredoxin peroxidase I (cTPx I), encoded by TSA1 (thiol-specific antioxidant), was investigated in the oxidative stress response of Saccharomyces cerevisiae. In most cases, deletion of TSA1 has showed only a slight effect on hydrogen peroxide sensitivity. However, when the functional state of the mitochondria was compromised, the necessity of TSA1 in cell protection against this oxidant was much more evident. All the procedures used to disrupt the mitochondrial respiratory chain promoted increases in the generation of H(2)O(2) in cells, which could be related to their elevated sensitivity to oxidative stress. In fact, TSA1 is highly expressed when cells with respiratory deficiency are exposed to H(2)O(2). In conclusion, our results indicate that cTPx I is a key component of the antioxidant defense in respiratory-deficient cells.

Antioxidants↗
PubMed2000

The genome sequence of the plant pathogen Xylella fastidiosa. The Xylella fastidiosa Consortium of the Organization for Nucleotide Sequencing and Analysis.

Xylella fastidiosa is a fastidious, xylem-limited bacterium that causes a range of economically important plant diseases. Here we report the complete genome sequence of X. fastidiosa clone 9a5c, which causes citrus variegated chlorosis--a serious disease of orange trees. The genome comprises a 52.7% GC-rich 2,679,305-base-pair (bp) circular chromosome and two plasmids of 51,158 bp and 1,285 bp. We can assign putative functions to 47% of the 2,904 predicted coding regions. Efficient metabolic functions are predicted, with sugars as the principal energy and carbon source, supporting existence in the nutrient-poor xylem sap. The mechanisms associated with pathogenicity and virulence involve toxins, antibiotics and ion sequestration systems, as well as bacterium-bacterium and bacterium-host interactions mediated by a range of proteins. Orthologues of some of these proteins have only been identified in animal and human pathogens; their presence in X. fastidiosa indicates that the molecular basis for bacterial pathogenicity is both conserved and independent of host. At least 83 genes are bacteriophage-derived and include virulence-associated genes from other bacteria, providing direct evidence of phage-mediated horizontal gene transfer.

Bacterial Adhesion↗
PubMed2000

Cell surface components and adhesion in Corynebacterium diphtheriae.

Main primary approaches and new developments in the study of the molecular basis of the adhesive process of Corynebacterium diphtheriae are reviewed along with a discussion of the potential importance of hemagglutinins, exposed sugar residues, hydrophobins and trans-sialidase enzymes as adhesins of strains of the sucrose fermenting and non-fermenting biotypes.

Bacterial Adhesion↗
PubMed1996

Influence of early postnatal gonadal hormones on anxiety in adult male rats.

Behavioral sex differences have been linked to the presence of testosterone secretion during a critical perinatal period. The present experiment tested whether or not castration at different ages (early postnatal period and adulthood) would alter performance in the plus maze, a behavioral test of anxiety. Intact adult male rats (n = 17) were compared to intact adult females (n = 17); adult castrated males (n = 7) to sham-operated adult male rats (n = 9); and newborn castrated males (n = 7) to sham-operated male offspring (n = 8). When adult, the subjects were left on an elevated plus maze for 5 min. Females made a higher percentage of entries onto the open arms and showed a greater number of scans over the edge of an open arm than males. There were no differences in the percentage of arm entries or time spent on the open arms when adult castrated males were compared to sham-operated rats. On the other hand, newborn castrated males showed a significantly higher number of open arm entries and spent a greater percentage of time on the open arms than sham-operated offspring. The results demonstrate that the absence of male gonadal hormones during the perinatal period decreases anxiety, as assessed in the elevated plus maze, leading to a behavioral pattern that resembles that of females. These data provide evidence for the organizational role of gonadal hormones in the development of behavioral inhibitory systems.

Animals↗
PubMedDate not supplied

Portopulmonary hypertension syndrome in schistosomiasis mansoni.

Portopulmonary hypertension syndrome (PPHS) is a complication of portal hypertension where the substrate is micro-vessel lesions which are indicative of plexogenic arteriopathy. PPHS has not been linked to pulmonary schistosomiasis. We report, to the best of our knowledge for the first time, a case of PPHS associated with schistosomiasis mansoni.

Adult↗
PubMedDate not supplied

Corynebacterium diphtheriae threats in cancer patients.

The aim of this study was to determine the bacteriological properties of Corynebacterium diphtheriae strains isolated from bronchiole washing and cancer lesions. Bacteriological characterization included fluorescence/double sugar urease (King/DSU) screening tests, pyrazinamidase (PYZ), CAMP-reactions and radial immunodiffusion toxigenicity assay. Microorganisms produced fluorescence under ultraviolet light and were catalase positive; urea and aesculin hydrolysis negative; fermentation of glucose, maltose and sucrose and no fermentation of mannitol and xylose; PYZ and CAMP reaction negative. The API-Coryne system was used for bacterial preliminary identification at local hospital laboratory and produced numerical profiles 1010325 and 0010325 for sucrose positive C. diphtheriae var. mitis (nitrate positive) and C. diphtheriae var. belfanti (nitrate negative), respectively. The hemagglutination, adherence to glass and polystyrene assays evaluated adhesive characteristics. Strains were toxigenic and able to adhere to glass, polystyrene and human erythrocyte surfaces (titer 4). C. diphtheriae strains isolated from cancer patients expressed adhesive characteristics similar to strains isolated from immunocompetent hosts. Circulation of toxigenic C. diphtheriae continues to present a threat for children and adults including patients with cancer in hospital environment. Laboratories should remain alert to the possibility of isolation of diphtheria bacilli from adults with neoplastic disease.

Adult↗