Search PubMed⌕ Search

Biomedical subjects

A de Almeida

Publications and source records attributed to A de Almeida.

10 recordsLinked to original sources
PubMed2000

The Yersinia high-pathogenicity island is present in different members of the family Enterobacteriaceae.

A pathogenicity island termed high-pathogenicity island (HPI) is present in pathogenic Yersinia. This 35 to 45 kb island carries genes involved in synthesis, regulation and transport of the siderophore yersiniabactin. Recently, the HPI was also detected in various strains of Escherichia coli. In this study, the distribution of the HPI in the family Enterobacteriaceae was investigated. Among the 67 isolates pertaining to 18 genera and 52 species tested, nine (13.4%) harbored the island. These isolates were three E. coli, one Citrobacter diversus and five Klebsiella of various species (Klebsiella pneumoniae, Klebsiella rhinoscleromatis, Klebsiella ozaenae, Klebsiella planticola, and Klebsiella oxytoca). As in Yersinia sp., all nine isolates synthesized the HPI-encoded iron-repressible proteins HMWP1 and HMWP2. In the K. oxytoca strain, the right-end portion of the HPI was deleted, whereas the entire core region of the island was present in the eight other enterobacteria strains analyzed. In most of these isolates, the HPI was bordered by an asn tRNA locus, as in Yersinia sp. This report thus demonstrates the spread of the HPI among various members of the family Enterobacteriaceae.

Bacterial Outer Membrane Proteins↗
PubMed1999

Biased TCR repertoire in infiltrating lesional T cells in human Bancroftian filariasis.

To investigate the hypothesis that T cells recognizing specific Ags localize to the site of disease activity in human bancroftian filariasis, we have compared the repertoire of TCR Vbeta gene segments in lesions vs blood in individual patients by RT-PCR ELISA. Vbeta14 and Vbeta24 were overrepresented (5% greater in tissue compared with PBMCs and/or tissue/PBMC ratios in the highest 5% of all tissue/PBMC ratios for all Vbetas for all subjects) in 50% and 40% of study subjects, respectively. Overrepresentation of these two Vbetas did not occur in any control subject. In comparing three patient groups, the proportion of individuals meeting at least one criterion for Vbeta14 overrepresentation was shown to increase in tandem with our current concepts of disease progression (asymptomatic filariasis = 25%; clinical filariasis with active infection = 60%; clinical filariasis without active infection = 71%). In 6 of the 10 individuals with Vbeta14 overrepresentation, Vbeta14 represented >20% of the entire lesional Vbeta repertoire. All but one of the 20 study subjects had at least one Vbeta gene segment that was overrepresented in tissue compared with PBMCs. Only a small number of Vbetas, usually three or less, were overrepresented in any single filariasis patient. However, in the same tissue, no differences between patient groups were found when IFN-gamma, TNF-alpha, IL-4, IL-5, and IL-12 mRNA expression were examined. Taken together, these findings suggest that, in principle, in essentially all patients, whether with subclinical or with clinical filariasis, distinct and limited T cell populations are concentrated in affected tissue.

Animals↗
PubMed1999

Characterization of the reciprocity law failure in three mammography screen-film systems.

The purpose of this project was to quantify reciprocity law failure (RLF) for mammography screen-film systems. Three widely used screen-film systems were evaluated: the Kodak MinR 2000 system. Fuji UM Mammo Fine screen and Fuji UM MA HC film, and Agfa MR Detail screen and Agfa Mammoray MR5 film. The logit algorithm that linearizes logistic curve shapes was utilized to characterize film sensitometric response. Different values of mammographic phantom thickness, tube current, and kVp were used to vary screen-film exposure rates. RLF was quantified by examining the dependence of logit parameters (maximum and minimum film density, curve shift, and slope) on exposure rate. The shift of the logit curve was found to be a good indicator of the screen-film system speed, while the slope of the logit curve is affected by the RLF. RLF leads to changes in film contrast as well as speed. For the range of exposure rates measured (50-fold), screen-film contrast and speed varied by factors of 2 and 3.5, respectively. Film contrast decreased as exposure rate increased. The greatest changes were observed with the Kodak MinR 2000 screen-film system.

Mammography↗
PubMed1999

Mammography grid performance.

PURPOSE: To measure directly the grid performance of mammography units for the range of breast thicknesses and x-ray tube potentials encountered in clinical practice. MATERIALS AND METHODS: Contrast improvement factors and Bucky factors were determined for four mammographic units as a function of x-ray tube potential (25, 30, and 35 kVp), phantom thickness (2, 4, and 8 cm) and, on one unit, three target-filter combinations. Three units used a linear grid; one, a cellular grid. Two methods were used for nongrid measurements. RESULTS: For all units tested, contrast improvement factor increased with increased phantom thickness and with increased kilovolt peak level for the 8-cm-thick phantom and changed little with kilovolt peak level for 2- and 4-cm-thick phantoms. At 25 and 30 kVp, contrast improvement factor performance with the linear grids was comparable; with the cellular grid, it was 5%-10% higher. In all cases, the Bucky factor increased with increased phantom thickness and decreased with increased tube potential. CONCLUSION: Differences in grid performance exist. At 25 and 30 kVp, the cellular grid exhibited superior contrast improvement factor performance, whereas one of the linear grids exhibited superior Bucky factor performance. Measured contrast improvement and Bucky factors are dependent on nongrid technique. Cassette tunnels introduce scatter and should not be used with nongrid or magnification techniques.

Humans↗
PubMed1999

The Saccharomyces cerevisiae Cdc14 phosphatase is implicated in the structural organization of the nucleolus.

Cdc14, a dual-specificity protein phosphatase, has been previously implicated in triggering exit from mitosis in the yeast Saccharomyces cerevisiae. Using immunofluorescence microscopy and immunogold labeling, we demonstrate that a functional HA-tagged version of the phosphatase Cdc14 localizes to the nucleolus. Moreover, Cdc14-HA co-localized with the nucleolar NOP2 and GAR1 proteins. By immunofluorescence, Cdc14-HA was found in the nucleolus during most of the mitotic cell cycle, except during anaphase-telophase when it redistributed along the mitotic spindle. While this work was in progress, the same pattern of Cdc14 localization was described by others (Visintin et al, Nature 398 (1999) 818). Constitutive overexpression of CDC14 was toxic and led to cell cycle arrest of cells, mainly in G1. This correlated with the appearance of abnormal nuclear structures. A genetic search for suppressors of the lethality associated with CDC14 overexpression identified YJL076W. Because overproduction of Yj1076w buffered the toxic effect of Cdc14 overproduction, this suggested that it might be a substrate of Cdc14. This has indeed been found to be the case by others who recently described Yj1076w/Netl as a nucleolar protein that physically associates with Cdc14 (Shou et al, Cell 97 (1999) 233). The present data confirm several recently uncovered aspects of the regulation of Cdc14 localization and activity and suggest that the level of expression of CDC14 influences the structural organization of the nucleolus.

Cell Cycle↗
PubMed1998

The Cdc14 phosphatase is functionally associated with the Dbf2 protein kinase in Saccharomyces cerevisiae.

The Saccharomyces cerevisiae Cdc14 protein phosphatase and Dbf2 protein kinase have been implicated to act during late M phase, but their functions are not known. We report here that CDC14 is a low-copy suppressor of the dbf2-2 mutation at 37 degrees C. The kinase activity of Dbf2 accumulated at a high level, in vivo, during a cdc14 arrest and was also much higher in cdc14 mutant cells at the permissive temperature of growth, therefore in cycling mutant cells than in cycling wild-type cells. This correlated with the accumulation of the more slowly migrating form of Dbf2, previously shown to correspond to the hyperphosphorylated form of the protein. The finding that the dbf2-2 mutation could be rescued following overproduction of catalytically inactive forms of Cdc14 suggested that the control of Dbf2 activity by Cdc14 might be only indirect and independent of Cdc14 phosphatase activity. However, it was found that Cdc14 could form oligomers within the cell, thus leaving open the possibility that catalytically inactive Cdc14 might associate with wild-type Cdc14 and rescue dbf2-2 in a phosphatase-dependent manner. We confirmed that overexpression of CDC14 could rescue mutations in CDC15, which encodes another kinase also implicated to act in late M phase. Cells of a cdc15-2 dbf2-2 double mutant died at temperatures much lower than did either single mutant, whereas there was only a slight additive phenotype in the cdc14-1 dbf2-2 and cdc14-1 cdc15-2 double mutant cells. Finally, functional association between Cdc14 and Dbf2 (and also Cdc15) was confirmed by the finding that the cdc14, dbf2 and cdc15 mutations could be partially rescued by the addition of 1.2 M sorbitol to the culture medium. Our data are the first to demonstrate a functional link between Cdc14 and Dbf2 based on both biochemical and genetic information.

Cell Cycle↗
PubMed1992

[Intracavity brachytherapy in uterine neoplasms].

The growing use of intracavity treatment of uterine neoplasia has not been accompanied in the Brazilian literature by articles appropriate for day-to-day consultation. Based on this fact we endeavour to transmit in this paper our experiences related to this therapy technique.

Brachytherapy↗