Biomedical subjects
Publications and source records attributed to C Carvalho.
Independent lung ventilation with two ventilators is sometimes used in the management of bronchopleural fistula (BPF). We describe a patient in whom gas flow through a large BPF was initially reduced, and subsequently eliminated, during differential lung ventilation using a single ventilator and a variable-resistance valve attached to one lumen of a bifurcated endotracheal tube.
At present several lines of evidence indicate that the nucleus is functionally compartmentalized into discrete structures with defined properties. For instance, it is well established that the molecular machines involved in replication, transcription, and RNA processing assemble into morphological entities but it remains unclear whether these correspond to autonomous "organelles" or rather represent temporary accumulations of either active factors recruited onto DNA templates or inactive factors stored in the vicinity of genes. According to the latter view, the spatial distribution of genes during interphase should play a major role in the subnuclear organization of nonchromatin components such as replication, transcription, and processing factors, and in this article we discuss current ideas on the functional compartmentalization of chromosomes and genes within the nucleus.
Short-term cultures from an alveolar adenoma of the lung were cytogenetically examined. Of the 54 metaphases studied, 44 were characterized by an apparently normal karyotype and 10 showed a pseudodiploid karyotype: 46,XX,add(16)(q24). Fluorescence in situ hybridization studies permitted identification of the add(16)(q24) as a der(16)t(10;16)(q23;q24). This is the first report of a chromosomal aberration in an alveolar adenoma of the lung.
In the present study we analyzed the effect of ascorbate (0.8 mM)/Fe2+ (2.5 microM)-induced membrane lipid peroxidation on the levels of intracellular free calcium,[Ca2+]i and on the possible mechanisms involved in the perturbation of intracellular calcium homeostasis during oxidative stress. For this purpose, the influence of the ascorbate/iron oxidant system on the plasma membrane and endoplasmic reticulum Ca(2+)-dependent ATPases of brain cortical synaptosomes was studied. In addition, the influence of the peroxidative process on the uptake of calcium (45Ca2+) and on the Na+/Ca2+ exchange activity at the plasma membrane was evaluated. After ascorbate/Fe(2+)-induced membrane lipid peroxidation of the order of 18.05 +/- 4.20 nmol TBARS/mg protein, an increase in [Ca2+]i occurred, under basal or depolarizing conditions (30 mM KCl), which was dependent on the extracellular calcium concentration. Thus, for 1 and 3 mM extracellular calcium concentration, an increase of the resting [Ca2+]i values of 19.8% and 33.7% was observed, while after the K(+)-depolarization the enhancement of the [Ca2+]i was 18.4% and 29.5%, respectively. The Na+/Ca2+ exchange activity and the time-dependent influx of 45Ca2+ observed in basal conditions and after the 30 mM K(+)-depolarization, were not affected under the peroxidative conditions. The Ca(2+)-dependent ATPase activity of the synaptosomal plasma membrane was significantly depressed following peroxidation of membrane lipids, decreasing the V(max) by 48.1%, without significant changes in the affinity of the enzyme for calcium (K(m) for Ca2+ was 0.54 +/- 0.04 microM in control conditions and 0.56 +/- 0.034 microM in peroxidized conditions). The Ca(2+)-ATPase activity of the endoplasmic reticulum was also affected during ascorbate/iron-induced oxidative stress; thus, an inhibition of 45.2% was observed 5 min after adding ATP. These data suggest that the increase in synaptosomal [Ca2+]i due to oxidative stress may result from the inhibition of the plasma membrane and the endoplasmic reticulum membrane Ca(2+)-ATPase activities, probably as a result of the alteration of the lipid environment required for the maximal activity of these membrane enzymes. The consequent increase in [Ca2+]i may be responsible for the injury of the nervous tissue observed during several pathological conditions in which free radical generation seems to be involved.
Explore the source record for details and available documents.
During a multicenter surveillance study on Streptococcus pneumoniae resistant to antibiotics in Portugal we have analyzed, within the predominant serotypes of penicillin G resistant strains, the chromosomal DNA restriction profiles by pulsed field gel electrophoresis. The aim of this work was to compare the PFGE restriction profiles of penicillin resistant pneumococci isolated in France with those of Portuguese strains within each serotype. We have studied fifteen penicillin resistant strains isolated in different geographical regions of France, and representing equally the three predominant resistant serotypes 23F, 9V and 14. In general we observed an important homogeneity of profiles within each serotype, in the two countries. In serotype 23F, the five French strains studied show subtypes of a pattern called A, also detected in the majority of 23F Portuguese strains; similarly 4 of the 5 serotype 9V strains belong to subtypes of the pattern G, also common within 9V Portuguese strains; 4 of the 5 strains of serotype 14 show a subtype of profile H, found often in Portuguese strains. The observed homogeneity of chromosomal DNA restriction profiles within each serotype in the two countries, confirms the importance of geographic spread of pneumococcal resistant clones, previously described.
An interphase cytogenetics analysis was performed to investigate whether replication and transcription could influence in situ resolution of immunoglobulin (Ig) heavy chain constant region genes. A plasmid probe recognizing five C gamma segments separated by known linear DNA distances was hybridized in situ and visualized by digital fluorescence microscopy. In interphase nuclei from phytohemagglutinin (PHA)-stimulated lymphocytes, the gamma genes were resolved as one to three signals per allele in the majority of nuclei, whereas in a minority, complex patterns of several signals per allele could be observed. The latter were restricted to nuclei in an early stage of the S phase, as assessed by hybridization experiments performed in cells grown in the presence of bromodeoxyuridine. To investigate whether the in situ resolution of the C gamma segments could vary as a function of the transcription activity of the locus, the C gamma probe was subsequently hybridized to nuclei from a mature B cell line (JVM-2), which produces gamma transcripts as shown by in situ RNA hybridization experiments. Primary human fibroblasts were further used as representative of a non-lymphoid cell type with transcriptionally inactive Ig genes. When Gl nuclei from the three cell types were compared in terms of the in situ resolution of the C gamma locus, JVM-2 cells were found to include the highest percentage of higher resolution patterns (three to five signals per allele in 28% of nuclei), fibroblasts the lowest (three signals per allele, 2%), while PHA-stimulated lymphocytes occupied an intermediate position between the other two cell types (three or four signals per allele, 15%). The data show that the in situ resolution of Ig C gamma genes varies throughout the cell cycle and is influenced by the transcriptional activity of the locus. The variability of the resolution patterns observed appears to reflect different levels of chromatin packaging, which in turn are likely to influence the probe accessibility to its target. These observations are relevant for the interpretation of data from interphase cytogenetics analysis of independent, but closely spaced, DNA segments.
Second trimester amniotic fluid placental alkaline phosphatase (PLAP) immunoreactivity was measured in 756 normal pregnancies, 63 Down's syndrome pregnancies and 42 pregnancies associated with other chromosomal abnormalities. PLAP levels were significantly reduced in cases of Down's syndrome (MoM = 0.72, U = 17,565, P = 0.0002, 95% Cl = 0.63-0.88). However, there was no significant difference between other aneuploid conditions and the normals (MoM = 0.88, U = 13,289, P = 0.35, 95% CI = 0.77-1.08). PLAP is the carrier protein for immunoglobulin G. Neonates with Downs syndrome but not other chromosomal abnormalities are associated with a deficiency of IgG. These data therefore support the theory that the low IgG levels in Downs syndrome are a result of a defect in PLAP transport.
Explore the source record for details and available documents.
AIMS: To evaluate the overall incidence of immunoglobulin (Ig) and T cell receptor (TCR) beta and gamma gene rearrangements in a series of 40 cases of acute myeloid leukaemia (AML) and to determine whether structural modifications of these genes could be correlated with the abnormal expression of lymphoid markers in malignant cells. METHODS: All cases were classified according to the criteria of the FAB group and immunophenotyped with a panel of monoclonal antibodies reactive with myeloid and lymphoid differentiation antigens. DNA analysis was performed by the method of Southern using probes for the Ig JH, TCR-C beta 1, and TCR-J tau 1 regions. RESULTS: Phenotypic analysis showed that in addition to myeloid markers, 10 cases expressed lymphoid antigens: CD7 in seven (of which three were TdT positive, one CD2 positive, and one CD19 positive) and CD19 in three. Southern blot analysis showed that bands with sizes different from the germ line control were present in the TCR beta genes in 11 cases: in six of 30 with pure myeloid phenotype and in five of 10 of those expressing lymphoid markers. A close observation of the size and patterns of those bands, however, showed that they could be artefactual. Indeed, further analysis showed that they were either due to resistant Eco RI/Hind III sites at the beta locus or to plasmid contamination. Rearranged genes were eventually found in only two of the 40 cases: at the Ig JH region in one of the 30 with pure myeloid phenotype (3.3%) and at the TCR gamma genes in one of 10 with lymphoid markers (10%). CONCLUSIONS: These observations showed that Ig/TCR gene rearrangements were rare in this AML series (overall incidence of 5%) and that they were not significantly more common in cases with aberrant expression of lymphoid markers. The size and pattern of the potential non-germline bands that can be found in these loci must be carefully evaluated.
Explore the source record for details and available documents.
Digoxin like immunoreactive factor (DLIF), has been implicated on the effect of sodium in essential hypertension. The different concentration of DLIF as a function of sodium intake was demonstrated in animal experience by some authors. In this work the urinary DLIF excretion is evaluated by RIA and its biological activity by Na+/K+ ATPase inhibition, in 5 urine samples at the end of a free sodium diet week and in 10 urine samples in the last day of a week with 250 mg sodium diet. The urinary DLIF excretion after the free sodium diet week was 0.3460 +/- 0.055 and at the end of sodium restriction diet week of 0.2910 +/- 0.061 nmol/l. Although the DLIF values in the sodium restriction week were smaller than the DLIF values of the free sodium diet week, there was no statistical difference (p = 0.113). In five patients the DLIF could be evaluated at the end of the first and second weeks without changes in the hypertensive therapeutics, with clonidine and nifedipine, along the two weeks. In these five patients at the end of the free sodium diet week and at end of the sodium restricted diet week were 0.3460 +/- 0.055 and 0.2780 +/- 0.060 nmol/l. The reduction of urinary DLIF excretion in the sodium restricted diet week, was significative (p = 0.020). The results of the Na/K ATPase inhibition in the same five patients were: 34.6 +/- 6.51% at the end of the free sodium diet week and 31.7 +/- 6.32% at the end of the sodium restricted diet week, the differences were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)
Explore the source record for details and available documents.
The authors report a new case of Townes-Brocks syndrome with cardiac defect, ossicular anomalies and dominant transmission. The intrafamilial variability of the phenotype and the difficulty of diagnosis in isolated cases are underlined.
Explore the source record for details and available documents.
Explore the source record for details and available documents.