Biomedical subjects

E Pásaro

Publications and source records attributed to E Pásaro.

9 recordsLinked to original sources

PubMed2005

Genotoxic effects in a population of nurses handling antineoplastic drugs, and relationship with genetic polymorphisms in DNA repair enzymes.

BACKGROUND: Concern about the genotoxic risk associated with chronic handling of antineoplastic drugs has increased, and usual safety practices may not avoid exposure. METHODS: Comet assay and MN test were performed on 30 oncology nurses and 22 controls. Genetic polymorphisms of XRCC1, XRCC3, and APE1 genes were determined by PCR-RFLP. RESULTS: Data obtained showed increased cytogenetic and DNA damage in the exposed group, although statistical significance was only reached in the comet assay. Significant differences in TL were observed for carriers of the variant alleles of every gene analyzed. However, no significant effect was detected in the MN test. CONCLUSIONS: Evidence that the present handling practices of antineoplastic drugs in some Portuguese hospitals are not enough to prevent exposure are provided. Present data suggest that genetic polymorphisms in the studied DNA repair enzymes may influence the individual susceptibility to DNA damage related to chronic handling of antineoplastic drugs.

Adult↗

PubMed2001

Genotoxic effects of styrene-7,8-oxide in human white blood cells: comet assay in relation to the induction of sister-chromatid exchanges and micronuclei.

Styrene is used in the production of plastics, resins and rubber. The highest human exposures to styrene take place by inhalation during the production of fiberglass reinforced plastics. Styrene is metabolized mainly in the liver to styrene-7,8-oxide (SO), its principal in vivo mutagenic metabolite. In this study, human peripheral white blood cells were exposed to several SO concentrations (10-200 microM) in order to evaluate its genotoxic properties by means of comet assay, sister-chromatid exchanges (SCE) and cytokinesis-blocked micronucleus (MN) test, in addition to determine its clastogenic or aneugenic properties by combining MN with fluorescence in situ hybridization (FISH) procedures. Our results show that SO induces DNA damage, SCE and MN in human leukocytes in vitro at concentrations above 50 microM, and that there is a strong relationship between DNA damage, as measured by the comet assay, and cytogenetic damage induced by SO at the doses employed. SO shows preferentially a clastogenic activity and produces a cytostatic effect at high doses, reflected by the significant decrease of the calculated proliferation indices. A good dose-effect relationship is obtained in the three tests performed at the concentration range assayed.

Adult↗

PubMed2001

Effects of styrene-7,8-oxide over p53, p21, bcl-2 and bax expression in human lymphocyte cultures.

Styrene is one of the most important organic chemicals in use today. The highest human exposures to styrene take place by inhalation during the production of fibreglass-reinforced plastics. Styrene is oxidized by hepatic cytochrome P450 to styrene-7,8-oxide (SO), an epoxide that has been shown to induce chromosome aberrations, sister chromatid exchanges and micronuclei in many cell systems. In this work, the effect of SO on the expression of some genes involved in the cell cycle and apoptosis regulation in human white blood cells was studied. Lymphocyte cultures from four donors were exposed to 50 and 200 microM SO, 1% DMSO being the control. Aliquots of the cultures were taken at six different time points (30, 36, 42, 48, 60 and 72 h), total mRNA was extracted in each one of them and RT-PCR was carried out to analyze the expression of the genes p53, p21, bcl-2 and bax. Moreover, a cytokinesis block assay was performed to estimate cell proliferation kinetics by calculating the cytokinesis block proliferation index (CBPI), and to evaluate the number of cells undergoing apoptosis. Furthermore, apoptotic events were detected by the DNA fragmentation assay. In our results, a high interindividual variation in the expression of the studied genes was observed. Expression curves obtained for the four genes, together with the data from the CBPI and apoptotic cells scored, suggest that exposure to high levels of SO may induce a delay in the cell cycle, probably directed to allowing repair systems to act on the genotoxic damage produced, more than driving cells towards programmed cell death.

Adult↗

PubMed2000

Analysis of sex chromosome aneuploidy in 41 patients with Turner syndrome: a study of 'hidden' mosaicism.

We performed a genetic study of sex chromosome mosaicism in 41 Turner syndrome patients. The investigation was carried out in four phases: cytogenetics (G-banding), FISH, PCR for SRY in all 41 cases, and sequencing of the SRY gene in the 2 patients with the Y chromosome. The application of classical alpha-satellite probes (CEP-X and CEP-Y), painting probes (WCP-X and WCP-Y) and also XIST, DXZ4 and two subchromosomal painting libraries (SCPL 116 and SCPL102) covering the short and the long arm of the X chromosome, respectively, allowed us to find new mosaic cell lines (mosaicism) in 37 out of 41 patients; only 4 patients were defined as 45,X non-mosaic. The most frequent hidden mosaic was 45,X/46,XX in 32% of the cases; the presence of isochromosomes comprised 25% and markers 5%. The patients who had been previously diagnosed as mosaics displayed a higher complexity in their karyotypes due to the presence of new cell lines. The Y chromosome and the SRY gene were present in blood and ovarian tissue in 2 patients with karyotypes 45,X/46,XY and 45,X/46,X,idic(Ynf). In both patients, the sequencing of the SRY gene confirmed a nucleotide sequence identical to that of a control male. Our results support the hypothesis of 'the necessity of mosaicism for survival', and thus, a mitotic origin for this syndrome.

Aneuploidy↗

PubMed1996

Turner syndrome: a study of chromosomal mosaicism.

We report the results of a molecular investigation of 25 patients who had Turner syndrome and who had previously been subject to analysis using cytogenetic techniques. When in situ hybridization and polymerase chain reaction (PCR) techniques were applied, a larger number of mosaic individuals were observed than were detected by cytogenetic methods. This was mainly because of the presence of the cell line 46,XX. The most frequent mosaics were 45,X/46,XX (36%); the presence of isochromosomes comprised 24% and fragments 12%. The patients who had been previously diagnosed with mosaicism displayed a higher complexity in their karyotypes because of the presence of new cellular lines. The isodicentric X chromosome for the long arm, idic(Xq), gave rise to complex mosaics of up to nine cell lines. The application of fluorescence in situ hybridization and PCR led to a clearer definition of alterations at the centromeric level and the identification of the nature of chromosome fragments.

DNA Probes↗

PubMed1993

Optical density profile analysis of trypsin-Giemsa bands in human X-chromosomes.

Mean Optical Density (M.O.D.) determination of six G-bands on X-chromosomes was performed on 45 patients with Turner's syndrome and compared with X-chromosomes from women controls with a normal karyotype by a Chromosome Image Analysis System. Density profiles were constructed to obtain standard values for the staining intensity and frequency of occurrence of chromosome bands. Statistical analysis showed that the M.O.D. were significantly different for Xq12, Xq21, Xq25 and Xq27 G-bands between the Turner and Control groups. Most within-group differences were small and appeared not to be statistically significant.

Azure Stains↗

PubMed1992

Influence of chromosome condensation and preparative chromosome methods on chromatid volume.

Human metaphase chromosomes 1 and 2 were examined by electron microscopy. Volumetric determinations were calculated on non-treated isolated chromosomes and spread metaphases treated with ammoniacal silver carbonate (ASC). Chromatid volume increased from early-metaphase to late-metaphase and this increase was statistically significant. A similar relationship was found when chromosomes with differentially condensed sister chromatids were studied. The more condensed chromatid volume was greater than its less condensed sister chromatid. ASC treatment produced structural changes in chromosomes which caused an increase of volume in relation to the isolated chromosomes.

Cells, Cultured↗

PubMed1987

Morphological parameter variations between sister chromatids by electron microscopy.

Five morphological parameters of sister chromatids, viz radius, length, centromeric index, volume and centromere width, were studied by electron microscopy, from 140 human number 1 chromosomes, and 122 human number 2 chromosomes. The degree of variation obtained ranged from 0.277 +/- 0.003% and 0.286 +/- 0.005% for the centromeric index of chromosomes 1 and 2, respectively, to 9.835 +/- 0.933% and 13.472 +/- 1.461% for centromere width.

Cells, Cultured↗

PubMedDate not supplied

Fluorescence in situ hybridization of psu dic(X)(Xpter-Xq21::Xq21-Xpter) in two patients with Turner's syndrome.

Dicentric X chromosomes of different derivations were present in 6 out of a total of 42 patients with Turner's syndrome. The most unusual cases were observed in 2 patients having a psu dic(X)(Xpter-Xq21::Xq21-Xpter) in mosaic form who were examined by fluorescence in situ hybridization. Alu-PCR products from hybrid cell lines were used as partial chromosome paints for the p arm of the human X chromosomes. The other 4 patients displayed isodicentric idic(Xq) in mosaic form. One of the patients displayed 9 cell lines originating from the accumulation of isodicentric idic(Xq) chromosomes, along with loss of chromosome material which resulted in fragments of varying size.

Chromosome Aberrations↗