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B Molina

Publications and source records attributed to B Molina.

25 records · Page 2Linked to original sources
PubMedDate not supplied

[Effects of the addition of conditioned media on the response of Fanconi anemia lymphocytes to mitomycin C].

It has been shown that the addition of normal plasma to Fanconi anemia (FA) lymphocyte cultures significantly decreases the frequency of mitomycin C (MMC) induced chromosome aberrations, suggesting that normal plasma contains a diffusible correction factor (CF) which is able to partially complement FA lymphocytes. On the other hand, there is evidence suggesting that FA cells are defective in the DNA postreplicative repair. CF could then be involved in DNA repair processes and in possible inducible mechanisms. In the present study MMC-treated FA lymphocytes were grown during the last 24 hours of culture, in conditioned media obtained from untreated and MMC-treated normal cells. The purpose was to investigate if MMC-stressed normal cells were induced to produce CF in vitro. The results failed to show a constant decrease of FA cells chromosome aberrations when plasma-free conditioned media from MMC-stressed normal cells were added (experiments 2 and 3). However, when the conditioned media were supplemented with normal plasma (experiments 1 and 4) a partial repair of MMC-induced damage of the FA cells was observed. The results suggest the presence of CF in normal plasma and two possible mechanisms of action are suggested: CF is involved in DNA repair of MMC-damaged FA cells or it induces cellular division selecting the less damaged cell population through mitosis.

Culture Media, Conditioned↗
PubMedDate not supplied

[Effect of gamma radiations on robertsonian translocations].

Centromeric breaks and the dissociation of Robertsonian translocations have been regarded as the possible cause of a few reported cases of mosaicism. In a previous study we suggested that the dissociative phenomenon is influenced by an instability of the point of fusion, when it is located on a heterochromatic region, which appears to be a preferential mitomycin C (MMC) breakpoint. In this study lymphocytes from 6 robertsonian translocation carriers were treated with gamma rays. In one case who was a mosaic, the MMC induced a statistically significant increase in the number of cells with the dissociation. In the remaining cases, centromeric breaks or complete fissions were observed in 1.8% of the cells. In addition, the analysis of the distribution of breakage points on heterochromatic or euchromatic regions showed that almost 50% of the breaks on translocation chromosomes were located on pericentromeric heterochromatin. We postulate that the dissociation which occurs in robertsonian translocations may be caused by instability of the point of fusion since it is located on a heterochromatic region, susceptible to breakage by clastogenic agents such as MMC and gamma rays.

Gamma Rays↗
PubMedDate not supplied

[Effect of mitomycin C (MMC) on the fusion points of reciprocal translocations].

Lymphocytes from five patients having a reciprocal translocation were exposed to MMC to test the stability of the point of reunion which was localized in an euchromatic region. The results showed that the point of fusion in this type of translocations in not a preferential breakpoint. In a patient carrier of a (1;7) translocation, the derivate chromosome showed a significant increased number of breaks compared with the homologous chromosomes. No explanation is available for this finding. Our results support the hypothesis that the observed dissociation of Robertsonian translocation is related to the fact that the point of reunion is located in a heterochromatic region.

Chromosome Fragility↗
PubMedDate not supplied

[Synergism of bromodeoxyuridine and mitomycin C in the production of chromosomal aberrations in Fanconi's anemia].

Synergism of BrdU and MMC on the production of chromosome aberrations in lymphocytes of patients with Fanconi's anemia (FA) was studied. With this purpose, the lymphocytes of an FA patient and of a normal subject were cultured and exposed to BrdU and to MMC in 6 different experiments. The results showed no synergism of these two agents in normal cells. However FA cells exposed to BrdU and MMC showed an increased frequency of aberrations suggesting synergism. Furthermore the chromosome damage produced by MMC was significantly increased by the presence of BrdU in the medium. These results support the hypothesis of a defect of DNA repair in FA cells.

Anemia, Aplastic↗
PubMedDate not supplied

[A new syndrome of mental retardation and chromosomic instability in 3 siblings].

We report on three brothers with mental retardation, microcephaly and prominent ears whose cytogenetic studies showed no fragile X. However, an elevated frequency of spontaneous chromosome aberrations compared with that in normal individuals was found. The chromosome aberrations included acentric fragments, rings, dicentrics and radial figures. The lymphocytes did not show an increased sensitivity to mitomycin C nor to gamma radiation. It is suggested that this is a new hereditary syndrome of mental retardation with chromosome instability, probably recessive X linked.

Child↗
PubMedDate not supplied

[Detection of aneuploidies using in situ hybridization in cells of the oral mucosa].

Aneuploidies have been traditionally diagnosed by chromosome analysis, however this method may be difficult to perform in certain cellular types or in severely ill patients. With the fluorescence in situ hybridization (FISH) technique it is possible to identify the number of specific chromosomes in interphase cells. In the present study we analyzed exfoliated epithelial cells from the oral mucosa of 15 patients with trisomy 21, and in six patients with mosaicism; five normal subjects were included for comparison. To allow the probe to reach its target DNA we first treated the keratin-surrounded membrane with pepsin during 20 minutes. In the 15 cases of trisomy 21, the cells showed five fluorescent signals indicating the presence of three chromosomes 21 and two 13, while the normal subjects showed four signals. In one girl with Turner syndrome and a karyotype 46,X+mar, the FISH analysis in 1000 cells revealed that the marker derived from chromosome X and there was a mosaicism 45,X/46,X,r(X). In the other patients with mosaicisms, we observed variations in the proportions of cells but the differences were not significant. In conclusion, interphase FISH on buccal cells showed to be a rapid, effective and non-invasive method for the diagnosis of chromosome aberrations, particularly when the cytogenetic study on lymphocytes is difficult to perform.

Aneuploidy↗