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J Egozcue

Publications and source records attributed to J Egozcue.

At least 19 recordsLinked to original sources
PubMed2001

Chromosomal abnormalities in sperm.

The use of FISH (fluorescent in situ hybridization) in decondensed sperm nuclei has allowed, during the last decade, to indirectly study the chromosome constitution of human spermatozoa. Studies in control populations have been used to set up the basal level of aneuploidy for all human chromosomes and, based on conservative estimates, the percentage of chromosomally abnormal sperm in the general population could be considered to be at least 6.7%. In carriers of sex chromosome numerical anomalies and in severe oligozoospermic males (both frequent candidates for intracytoplasmic sperm injection), in structural chromosome carriers (enrolled in preimplantation genetic diagnosis programs) and in couples with recurrent miscarriage, sperm chromosome analyses by FISH could help to better establish a reproductive prognosis.

Cell Nucleus↗
PubMed2001

Bends in human mitotic metaphase chromosomes revisited: 15q11-13 is the most frequent non-random autosomal bend in blood cultures.

We have investigated the preferential bending of some chromosome sites in blood cultures from normal and chromosomally abnormal subjects. A total of 2,262 centromeric and 2,718 non-centromeric bends were recorded, and 69 non-centromeric sites were found not to bend at random. 15q11-13 bending was found to be the most frequent non-random autosomal bend. Bends on chromosomes may be remnants of a folded chromosome state in the nucleus, and may facilitate the preferential involvement of some chromosomal bands in structural reorganizations such as the isoacentric fragments, or contribute to the high frequency of interstitial deletions and isodicentric inversion duplications involving the 15q11-13 region.

Blood Cells↗
PubMed2001

Cytogenetic sensitivity of three Fanconi anemia heterozygotes to bleomycin and ionizing radiation.

It is well known that Fanconi anemia (FA) patients show a hypersensitivity to the effect of cross-linking agents such as mitomycin C and diepoxybutane, while the sensitivity of these patients to ionizing radiation is controversial. Fanconi anemia heterozygotes do not show a hypersensitivity to the above-mentioned agents. However, bleomycin it is used to identify mutagen sensitive individuals, especially among head and neck cancer patients. We present here a preliminary study in which the mean frequencies of bleomycin-induced chromatid breaks (ctb) from three FA heterozygotes (X = 0.90, range 0.80-1.01) and 11 controls (X = 0.40, range 0.21-0.66) differ significantly (P<.001), indicating a high sensitivity to bleomycin of G(2) lymphocytes from these three FA heterozygotes. An increased sensitivity was not observed after exposure of G0 lymphocytes to 2 Gy of ionizing radiation.

Antimetabolites, Antineoplastic↗
PubMed2001

Assessment of the proportion of transgene-bearing sperm by fluorescence in situ hybridization: a novel approach for the detection of germline mosaicism in transgenic male founders.

Genetic mosaicism is frequent among transgenic animals produced by pronuclear microinjection. A successful method for the screening of founder animals for germline mosaicism prior to mating would greatly reduce the costs associated with the propagation of the transgenic lines, and improve the efficiency of transgenic livestock production. With this aim, we have devised a simple method to detect integrated transgenes in individual spermatozoa using fluorescence in situ hybridization (FISH). The experiments reported here were undertaken to investigate the efficiency of this FISH-based approach to accurately evaluate the proportion of transgene-bearing sperm and to be applied for the detection of potential germline mosaics. Sperm samples from mice homozygous and hemizygous for a beta-lactoglobulin transgene were analyzed in a first set of experiments. A high hybridization efficiency was achieved, and the proportions of transgene-positive sperm cells in both homozygous (94.8-98.2%) and hemizygous (49.8-51.9%) animals were close to the expected frequencies (100 and 50%, respectively). To evaluate the sensitivity of the assay more directly, simulated mosaic samples with 5, 10, 15, 20 and 40% of transgene-bearing spermatozoa were then prepared and analyzed by FISH. Significant differences in the frequency of transgene-positive sperm were observed between all mosaic samples, indicating that even small deviations (5%) from the expected 50% transgene transmission rate in a founder animal could be reliably detected with our assay. Therefore, the method proposed represents a novel approach for the identification of germline mosaic founder males in livestock transgenic projects and a much more economic and faster alternative to breeding.

Animals↗
PubMed2001

Embryolethality induced by metronidazole (MTZ) in Rattus norvegicus.

Parasitic illnesses is increasing all over the world, especially in developing countries, and metronidazole (MTZ) is the therapeutic agent usually administered to children as well as adults at the reproductive age. In this work, we propose an evaluation of MTZ in order to analyze the potential reproductive damage in females by using Rattus norvegicus (Sprague-Dawley) as an animal model. Adult female rats were mated after MTZ treatments, and they were sacrificed at 21 days of gestation. Different types of damage were evaluated by using mortality, phenotypic abnormalities and reproductive capacity as parameters, and were studied and scored in 70 adult specimens (450 g/bw). They were divided into five groups: a) untreated females as a control group; females treated with b) DMSO as a solvent control group or c) 500 mg/kg/bw of MTZ per day for 7 days as therapeutic dose (TD); d) a half therapeutic dose (HD); and e) a double therapeutic dose (DD). Pre-implantation death in MTZ-treated groups was not significantly different from controls. However, drug treatments significantly increased the frequency of post-implantation deaths and the dominant lethals were ranged between 12.0 % and 17.8 %.

Animals↗
PubMed2001

Numerical chromosome abnormalities in the spermatozoa of the fathers of children with trisomy 21 of paternal origin: generalised tendency to meiotic non-disjunction.

The purpose of this study was the evaluation of aneuploidy frequencies in the spermatozoa of two fathers (DP-4 and DP-5) who had children with Down syndrome (DS) of paternal origin and in whom a previous sperm analysis by fluoresence in situ hybridisation (FISH) had suggested a generalised tendency to meiotic non-disjunction. Sperm samples were simultaneously hybridised with FISH probes for chromosomes 4, 13 and 22. Disomy frequencies for each of the chromosomes and diploidy frequencies were compared with data obtained from nine control donors. Both DS fathers had a statistically significant increase in the frequency of disomy for chromosomes 13 and 22. DP-5 also had an increased frequency of diploid spermatozoa. Our data suggest that the two DS fathers have a generalised susceptibility to meiotic non-disjunction and that acrocentric chromosomes seem to be more sensitive to such disturbance in the meiotic process.

Child↗
PubMed2001

Acrocentric chromosome disomy is increased in spermatozoa from fathers of Turner syndrome patients.

The aim of the present study was to investigate whether there was an increase of aneuploidy in the sperm from fathers of Turner syndrome patients of paternal origin who, in a previous study, showed an elevated incidence of XY meiotic nondisjunction. Sperm disomy frequencies for chromosomes 4, 13, 18, 21 and 22 were assessed by fluorescence in situ hybridisation in four of these individuals. As a group, the Turner syndrome fathers showed a general increase in disomy frequencies for chromosomes 13, 21 and 22, with a statistically significant increase in disomy frequencies for chromosomes 13 and 22 in one of the fathers and for chromosome 21 in two of them. Data from a previous work carried out by us in two fathers of Down syndrome patients of paternal origin also revealed increased sperm disomy frequencies for chromosomes 13, 21 and 22. Pooled as one group, these six fathers of aneuploid offspring of paternal origin had a statistically significant increase in the frequency of nondisjunction for these chromosomes with respect to control individuals. Our findings indicate that there may be an association between fathering aneuploid offspring and increased frequencies of aneuploid spermatozoa. Such increases do not seem to be restricted to the chromosome pair responsible for the aneuploid offspring. Acrocentric chromosomes and other chromosome pairs that usually show only one chiasma during meiosis seem to be more susceptible to malsegregation.

Aneuploidy↗
PubMed2001

Detection of chromosomal imbalances in papillary bladder tumors by comparative genomic hybridization.

OBJECTIVES: To identify those genetic alterations that are associated with bladder cancer invasion and progression. METHODS: A total of 30 specimens of transitional cell carcinoma of the bladder were analyzed by comparative genomic hybridization. The results were compared and summarized with previously reported studies. RESULTS: The most frequent chromosome changes detected in our series of tumors were losses in 9q, 9p, 8p, and 11p and gains in 8q, 1q, 20q, and 11q. Three regions of deletion on chromosome 9 were delineated, at 9p21-p22, 9q13-q22, and 9q31-q34. Gains in 1q and losses on 11p were significantly more frequent in pT1G2 tumors than in superficial (pTa) ones. In our study, the most striking differences were seen between pT1G3 and pT1G2 tumors. Gains on 10p and 6p and losses at 5q, 6q, and 18q were significantly more frequent in the former. CONCLUSIONS: A summary of our results and those available from published reports suggest that several groups of chromosomal imbalances may be associated with specific steps along bladder cancer progression. These genetic changes assume two different patterns: those that are shared, but are more intensive in one stage than in the other, and those such as a gain on 3p that are unique to invasive tumors.

Carcinoma, Papillary↗
PubMed2001

Comparative genomic hybridization analysis of transitional cell carcinomas of the renal pelvis.

We used comparative genomic hybridization to analyze 10 primary tumor samples from patients with transitional cell carcinoma of the renal pelvis. The most frequent loss was located at 9q, that is, in 50% of the tumors. Gains of DNA sequences were most frequently observed in chromosome regions 1q21 approximately q23, 2p23 approximately p25, 8q21.1 approximately q22 and in the whole chromosome 20. High level amplifications at 1q21 approximately q25, 6p22 approximately p23, 8q21 approximately q22, 8q22 approximately q24.1, 11q13, and 12q14 approximately q21 were detected. Most of these regions have previously been reported to be involved in transitional cell carcinoma of the bladder, thus confirming the importance of an increasing number of chromosome imbalances in the development and progression of this type of tumors.

Aged↗
PubMed2001

Identification of two de novo partial trisomies by comparative genomic hybridization.

We report the use of comparative genomic hybridization (CGH) to define the extra chromosome region present in two de novo partial trisomies 15q25-qter and Xp21-pter, which could not be clarified by conventional G-banding. Investigation with fluorescence in situ hybridization (FISH) revealed that the partial trisomy corresponded to an unbalanced translocation between Y and 15 chromosomes in 1 patient and an unbalanced X/X reorganization in the other patient. The combination of classical karyotyping, CGH, and FISH is useful for the identification and characterization of partial trisomies in clinical diagnostic laboratories, in order to delineate the chromosome regions implicated in specific clinical disorders.

Child↗
PubMed2001

Meiotic segregation analysis in a t(4;8) carrier: comparison of FISH methods on sperm chromosome metaphases and interphase sperm nuclei.

Meiotic segregation of a t(4;8)(q28;p23) translocation carrier was determined by two different methods to compare the final results. A total of 352 sperm chromosome complements, obtained after human-hamster in vitro fertilisation, were analysed by whole chromosome painting, and 6590 sperm heads were studied by fluorescence in situ hybridisation (FISH). Frequencies of alternate, adjacent I, adjacent II and 3 : 1 segregations were, for sperm chromosomes, 35.5, 33.2, 19.9 and 11.3% respectively. For sperm head analysis, results were 30.5, 28.5, 20.5 and 19.5% respectively. There were no statistically significant differences between the two methods with respect to the observed frequencies of sperm with balanced and unbalanced chromosome constitutions. Among unbalanced gametes, the methods differed only in the frequency of 3 : 1 segregation (chi(2), P<0.0001). Different factors that could explain this result are discussed. To determine possible interchromosomal effects, multicolour FISH was used on sperm heads. Disomy rates of sex and 18 chromosomes were higher in the translocation carrier than in the control. The differences observed were statistically significant (P<0.0001 for chromosomes X and 18, and P=0.0091 for chromosome Y).

Adult↗
PubMed2001

Linear increase of diploidy in human sperm with age: a four-colour FISH study.

The aim of this study was to determine if donor age is associated with an increased incidence of diploidy and of disomy for the sex chromosomes and for chromosomes 6 and 21. We used simultaneous fluorescence in situ hybridisation (FISH) for chromosomes 6, 21, X and Y in sperm from 18 healthy donors, aged 24-74 years (mean 48.8 years). A total of 194 024 sperm were analysed, with a minimum of 10 000 sperm scored for each donor. Our results indicate a significant increase of the level of diploidy (P=0.002), and a marginal significance of total sex chromosome disomy (P=0.055) with age. No increase was observed for disomies XX, YY, XY, 21 or 6. The percentages of increase for disomy and for diploidy ranged from 0.3 to 17% for each 10-year period. Chromosomes 6 and 21 did not segregate preferentially with the X or Y chromosomes. Our findings show a linear trend association between age and diploidy in human males.

Adult↗
PubMed2001

Meiotic behaviour of the sex chromosomes in three patients with sex chromosome anomalies (47,XXY, mosaic 46,XY/47,XXY and 47,XYY) assessed by fluorescence in-situ hybridization.

Meiotic studies using multicolour fluorescent in-situ hybridization (FISH) and chromosome painting were carried out in three patients with sex chromosome anomalies (47,XXY; 46,XY/47,XXY and 47,XYY). In the two patients with Klinefelter syndrome, although variable percentages of XXY cells (88.5 and 28.3%) could be found in the pre-meiotic stages, none of the abnormal cells entered meiosis, and all pachytenes were XY. However, the abnormal testicular environment of these patients probably resulted in meiotic I non-disjunction, and a certain proportion of post-reductional cells were XY (18.3 and 1.7%). The fact that none of the spermatozoa were XY also suggests the existence of an arrest at the secondary spermatocyte or the spermatid level. In the XYY patient, most (95.9%) premeiotic cells were XYY. The percentage of XYY pachytenes was 57.9%. The sex chromosomes were either in close proximity (XYY) or the X chromosome was separated from the two Ys (X + YY). A high proportion (42.1%) of post-reductional germ cells were XY. However, only 0.11% of spermatozoa were disomic for the sex chromosomes. In this case, the data suggest the existence of an arrest of the abnormal cells at the primary and the secondary spermatocyte or the spermatid level, giving rise to the continuous elimination of abnormal cells in the germ-cell line along spermatogenesis. The fact that the proportion of diploid spermatozoa was only increased in one of the three cases (XXY) is also suggestive of an arrest of the abnormal cell lines in these patients. The two apparently non-mosaic patients were, in fact, germ-cell mosaics. This suggests that the cytogenetic criteria used to define non-mosaic patients may be inadequate; thus, the risk of intracytoplasmic sperm injection in apparently non-mosaics may be lower than expected.

Adult↗
PubMed2001

Clinical application of multiplex quantitative fluorescent polymerase chain reaction (QF-PCR) for the rapid prenatal detection of common chromosome aneuploidies.

The clinical application of quantitative fluorescent polymerase chain reaction (QF-PCR) for rapid prenatal detection of chromosome aneuploidies has been limited in most studies to the detection of autosomal trisomies. Recently it has been shown that a newly identified highly polymorphic marker, termed X22, which maps to the Xq/Yq pseudoautosomal region of the sex chromosomes, used together with the X-linked short tandem repeat (STR) HPRT, allows the accurate detection of gonosome aneuploidies. We have developed a rapid assay, which includes these STR markers together with a sequence of the amelogenin region of the sex chromosomes and selected highly polymorphic autosomal STR. Two more X chromosome markers, as yet not used in previous QF-PCR applications, were also included in the assay. The molecular test was then used in a clinical trial on 551 uncultured amniotic fluid samples, allowing the assessment of copy number for chromosomes X, Y and 21 in 100% of cases. In the course of this study, two fetuses with Turner's syndrome and one with Klinefelter's syndrome were identified along with 17 autosomal trisomies. The assay proved to be so efficient and reliable that in most aneuploidy cases, in which ultrasound findings were in agreement with the molecular result, therapeutical interventions were possible without waiting for the result of cytogenetic analysis.

Adult↗
PubMed2001

Synaptic behaviour of some structural and numerical chromosome anomalies in female and male rats (Rattus norvegicus).

The processes of synapsis and synaptic adjustment have been detected in some structural and numerical anomalies in two female rat foetuses and in one male rat in the course of a study on X-ray genotoxicity. The synaptic characteristics and adjustment of one pericentric inversion and a deletion have been analysed by electron microscopy in synaptonemal complex spreads from two female foetuses, and the synaptic behaviour of a trisomy has been studied in a testicular biopsy from an adult male. In a large proportion (from 50% to 90%) of the analysed cells, the abnormal meiotic configuration could not be detected either because the anomaly was present in mosaic from trisomy or because synaptic adjustment had already taken place (inversion) or as result of a combination of two of the above (deletion).

Animals↗
PubMed2001

Cytogenetic analyses by fluorescence in situ hybridization (FISH) in hospital workers occupationally exposed to low levels of ionizing radiation.

An occupationally exposed population has been studied to evaluate the suitability of FISH painting techniques to detect chronic exposures to very low doses of ionizing radiation by the analysis of translocations. Whole-chromosome painting probes for chromosomes 1, 4 and 11 in combination with a pancentromeric probe have been employed. For comparison, a matched control population has also been studied. The mean genomic frequencies per 100 cells of total translocations in the control and exposed populations were 0.90 +/- 0.12 and 1.04 +/- 0.11, respectively. In the occupationally exposed population, no correlation between the frequencies of translocations and the doses received was found. When the two populations were compared, no significant differences were observed for the frequencies of the different chromosomal abnormalities examined. The absence of differences between control and exposed populations could be attributed to the very low-dose exposures recorded in the occupationally exposed population and to the wide range of individual frequencies of translocations observed.

Adult↗
PubMed2001

Non-disjunction and chromosome loss in gamma-irradiated human lymphocytes: a fluorescence in situ hybridization analysis using centromere-specific probes.

Centromere-specific DNA probes for chromosomes 4, 7 and 18 were used to simultaneously analyze chromosome loss, non-disjunction, breaks within the labeled region, and nucleoplasmic bridges induced by gamma rays in binucleated human lymphocytes. The doses used were 0, 1, 2 and 4 Gy, and approximately 1000 cells were scored per dose. Micronucleus frequency increased in a linear-quadratic fashion. For chromosome loss, significant increases were observed at 2 and 4 Gy, whereas for non-disjunction significant increases were observed at 1 Gy; thus non-disjunction allowed us to detect the effects of radiation at a lower dose than chromosome loss. The use of centromere-specific probes allowed discrimination between the clastogenic and aneugenic effects of ionizing radiation. The analysis of chromosome loss, not taking fragmented signals into account, ensures the detection of an aneugenic effect, which was not possible using pancentromeric probes. The frequency of chromosome breakage within the labeled regions was higher in nuclei than in micronuclei, suggesting an increase in the engulfment of chromosomal material by nuclei as a consequence of the presence of cytochalasin B in the cultures. Chromatin filaments connecting main nuclei, the so-called nucleoplasmic bridges, were observed in irradiated samples, and are a manifestation of rearranged chromosomes producing anaphase bridges.

Centromere↗