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J Egozcue

Publications and source records attributed to J Egozcue.

At least 145 records · Page 8Linked to original sources
PubMed1995

Induction of micronuclei in human sperm-hamster egg hybrids at the two-cell stage after in vitro gamma-irradiation of human spermatozoa.

The efficiency of the micronucleus test to assess radiation-induced chromosomal damage in human spermatozoa has been investigated. Micronuclei were scored in human sperm-hamster egg hybrids at the two-cell stage, after exposure of human spermatozoa to in vitro gamma-rays at doses of 0.00, 0.10, 0.25, 0.50, 1.00, 2.00, and 4.00 Gy. The relationship between the yield of micronuclei per two-cell stage as well as the percentage of two-cell stages with micronuclei and the different doses of irradiation were fitted to linear equations. To evaluate whether scoring micronuclei is useful for the quantification of chromosomal damage occurring in human spermatozoa, induced micronuclei at the different doses of sperm irradiation were compared to the induction of breaks and fragments in sperm-derived chromosomes. After interspecific fertilization of zona-free hamster oocytes by irradiated spermatozoa, a total of 699 fertilized eggs at the two-cell stage and a total of 387 sperm-derived complements were analyzed. The incidence of fertilized eggs with micronuclei at the two-cell stage coincided well with the incidence of sperm-derived chromosome breaks and fragments (e.g., 8.9% vs. 6.7% in the 0.25 Gy group and 52.8% vs. 58.6% in the 4.00 Gy group). A similar correlation was found between the number of micronuclei per two-cell stage and the number of breaks and fragments per sperm complement (0.09 vs. 0.07 in the 0.25 Gy group and 0.71 vs. 0.81 in the 4.00 Gy group). The results show that this test system can be used for the quantification of spontaneous or induced chromosomal damage in human spermatozoa.

Animals↗
PubMed1995

Establishment and validation of a dose-effect curve for gamma-rays by cytogenetic analysis.

A dose-effect curve obtained by analysis of dicentric chromosomes after irradiation of peripheral blood samples, from one donor, at 11 different doses of gamma-rays is presented. For the elaboration of this curve, more than 18,000 first division metaphases have been analyzed. The results fit very well to the linear-quadratic model. To validate the curve, samples from six individuals (three controls and three occupationally exposed persons) were irradiated at 2 Gy. The results obtained, when compared with the curve, showed that in all cases the 95% confidence interval included the 2 Gy dose, with estimated dose ranges from 1.82 to 2.19 Gy.

Blood↗
PubMed1995

Cyclophosphamide-induced synaptonemal complex damage during meiotic prophase of female Rattus norvegicus.

The reproductive system can be especially sensitive to the toxic, carcinogenic or mutagenic effects of alkylating agents. However, since studies of such effects on germ cells are complex, their analysis has been frequently overlooked. In humans, occupational or therapeutic exposure to cyclophosphamide has been associated with male (azoospermia) and female (ovarian failure) sterility or infertility. In this work, we have studied the effect of cyclophosphamide on the formation of the synaptonemal complexes in female rat fetuses. Our results indicate that cyclophosphamide administered at 16 days of gestation, when most germ cells are in a proliferative stage in the female rat, significantly increases the frequency of synaptonemal complex and nucleolar fragmentation in a dose-dependent way.

Animals↗
PubMed1995

Isochromosome 14q in childhood acute lymphoblastic leukemia.

We report a case of childhood acute lymphoblastic leukemia (ALL) with an isochromosome 14q as the sole abnormality. A review of the literature revealed that isochromosome 14 has not been previously reported in ALL. The prognostic significance of this abnormality is compared with that of other hematologic disorders with trisomy 14.

Child↗
PubMed1995

Cytogenetic studies of oocyte fusion products.

We describe for the first time the cytogenetic characteristics of mouse 'embryos' obtained by oocyte fusion (oocyte fusion products; OFP). Our results indicate that, after fusion, meiosis II is resumed correctly, with extrusion of two haploid polar bodies, and that metaphase synchronisation of the two haploid sets and chromosome segregation during the first cleavage are also normal.

Animals↗
PubMed1995

Occupational exposure to radiation induces an adaptive response in human lymphocytes.

The in vitro pretreatment of phytohaemagglutinin stimulated human lymphocytes with tritiated thymidine or with low doses of X-rays induces a response that makes these cells less susceptible to further genetic damage induced by subsequent high doses of radiation. This phenomenon has been called 'Adaptive Response' because it is similar to the one described in E. coli. In the present study, we describe that lymphocytes irradiated in vitro at 2 Gy, from individuals occupationally exposed to X and gamma rays, show lower frequencies of dicentrics than those from non-occupationally exposed individuals irradiated in the same conditions. Our results could indicate that an adaptive response can also be induced in lymphocytes in vivo by very low occupational doses of radiation, and that for biological dosimetry purposes it is necessary to know the individual's history of exposure to mutagens.

Adaptation, Physiological↗
PubMed1995

Human origin of micronuclei in human x hamster two-cell embryos.

Using fluorescence in situ hybridization techniques with either human or hamster genomic DNA probes, we studied the origin of micronuclei in two-cell hybrid embryos obtained from hamster oocytes and gamma-irradiated human spermatozoa. Our study demonstrates that over 99% of micronuclei hybridize with human DNA probes and not with hamster DNA, revealing their human origin. Thus, the micronucleus test represents a good method to evaluate genetic damage in human germ cells, since it is simpler and faster than sperm chromosome studies.

Animals↗
PubMed1995

Evaluation of cytogenetic analysis for clinical preimplantation diagnosis.

OBJECTIVE: To evaluate the feasibility of using cytogenetic analysis in preimplantation diagnosis. DESIGN: Two different biopsy protocols (chemical drilling and zona cutting) and two fixation methods were tested in a mouse model. Afterwards, the efficiency of obtaining chromosome preparations from untransferable human embryos depending on the method used to obtain the blastomeres (embryos biopsy or removal of the zona pellucida and blastomere disaggregation) was determined. The chances of obtaining chromosome preparations depending on the type of embryo (haploid, diploid, triploid, and apparently unfertilized) were also evaluated. RESULTS: Results from the mouse model showed that chemical drilling yields better results than cutting in terms of metaphases per biopsied embryo and surviving rate after biopsy. In human embryos, biopsy of diploid embryos produced 46.6% chromosome preparations, while 29% were obtained after blastomere disaggregation and 20.4% when biopsying triploid embryos. CONCLUSIONS: These results suggest that the disaggregating procedure and triploid embryos cannot be considered as good models to assess the feasibility of cytogenetic analysis in preimplantation diagnosis. Poor chromosome quality and loss during fixation are the main problems to use cytogenetics in preimplantation diagnosis; a combination of cytogenetics and other techniques is suggested in cases of balanced translocations.

Animals↗
PubMed1994

Ultrastructural studies of early mouse embryos obtained by oocyte fusion.

Oocyte fusion induced by inactivated Sendai virus results in the production of 'zygotes' that are able to undergo the first stages of embryonic development. The oocyte fusion products (OFP) obtained follow a morphological developmental pattern equivalent to that of control embryos, at least up to the 8-cell stage. The percentage of OFP that reach the 8-cell stage is extremely low (3%) compared with control embryos cultured in vitro (95%). On light microscopy, the OFP obtained show morphological characteristics identical to control embryos, although their cell diameters are larger. The cortical reaction, meiotic reactivation, extrusion of second polar bodies and pronucleus formation take place as observed in controls. The ultrastructural characteristics of oocyte fusion products at the 1-, 2-, 4- and 8-cell stages are analogous to those of controls, including the presence of structures related to the activation of the embryo genome. However some differences concerning cell ultrastructure, mainly in the nucleus, are observed and discussed in the text.

Animals↗
PubMed1994

Which semen parameters have a predictive value for pregnancy in infertile couples?

A prospective study was carried out in 156 couples attending an infertility clinic. To assess the predictive value of semen parameters in relation to pregnancy, we defined a group of 16 couples (group II) in whom the female became pregnant by intra-uterine insemination (IUI), and therefore in whom a female factor could be ruled out. Studies of semen parameters before and after capacitation were carried out in the first trimester of pregnancy (< 12 weeks). The same studies were done in the remaining 140 men (group III) with primary infertility and then all results were compared with a control group of 27 healthy, fertile men (group I), with normal semen parameters. Our results showed that progressive motility and straight line velocity were significantly lower in group III compared with group II: 33.4 and 45.2% respectively (P < 0.001) for progressive motility, and 25.7 and 32.8% respectively (P < 0.005) for straight line velocity. Acrosome alterations, on the other hand, were significantly more frequent in group III compared with group II: 21.4 +/- 0.7 and 5.9 +/- 1.7 respectively (P < 0.003). After capacitation, the recovery in terms of numbers of motile spermatozoa, spermatozoa with normal morphology and acrosome-reacted spermatozoa could be a predictive parameter of fertilization, because all were significantly decreased in group III compared with group II (P < 0.01).

Acrosome↗
PubMed1994

Sexing sibling mouse blastomeres by polymerase chain reaction and fluorescent in-situ hybridization.

The diagnosis of human genetic diseases at preimplantation stages allows the transmission of genetic anomalies in high risk couples to be prevented. Embryo sexing can be carried out using the polymerase chain reaction (PCR) or by fluorescent in-situ hybridization (FISH). However, it is still questionable whether the results obtained from a single analysed cell are fully predictive of the genetic characteristics of the whole embryo. We have isolated all the blastomeres from 4-cell stage mouse embryos and analysed them by PCR and FISH to assess the consistency of the results obtained. One half of each embryo (2/4-embryo) was spread and fixed to be processed by FISH, while the blastomeres of the other half embryo were isolated (1/4 + 1/4-embryo) and individually processed for PCR. We have determined the efficiency of both techniques when applied to different cells of the same embryo. We were able to amplify 92.5% of the embryos. Of these, 91.8% were classified as male or female, while the remaining 8.2% gave contradictory results (one male and its sibling blastomere female). Of the 40 embryos analysed by FISH, 97.5% could be classified as male or female with a sex distribution close to the expected 1:1. When comparing both techniques, 24 out of 36 embryos gave the same result. In nine cases the results did not coincide, and in three embryos comparison was not possible because of PCR contradictory results.

Animals↗
PubMed1994

Twin pregnancy after preimplantation diagnosis for sex selection.

A twin female pregnancy was obtained in a haemophilia carrier after two preimplantation diagnosis cycles. The embryonic sex of biopsied blastomeres was determined with the use of dual fluorescence in-situ hybridization with directly labelled DNA probes specific for the X and Y chromosome. A twin female pregnancy was confirmed by means of ultrasonography and amniocentesis at the 14th week of amenorrhoea. The patient delivered two healthy females by Caesarian section at the 37th week of pregnancy.

Adult↗
PubMed1993

Cytogenetic analysis of lymphocytes from hospital workers occupationally exposed to low levels of ionizing radiation.

Cytogenetic studies were performed in lymphocytes from hospital workers exposed to low doses of radiation (1.6-42.71 mSv). When compared with controls, exposed workers showed a significant increase in structural chromosome-type aberrations, acentric fragments being the most frequent alteration. Our results suggest that acentric fragments are good indicators of exposure to very low doses of radiation, although no dose-effect correlation was observed. The incidence of numerical abnormalities (hyperdiploidy) was significantly increased.

Adult↗
PubMed1993

A case of transitional cell carcinoma of the bladder with a del(9)(q11q21.2).

Monosomy for chromosome 9, as well as loss of heterozygosity for markers on this chromosome, has been detected in a high percentage of transitional cell carcinomas (TCC) of the bladder. We report a case of a TCC of the bladder with an interstitial del(9)(q11q21.2) that could be indicative of the presence of a putative tumor-suppressor gene related to bladder tumor progression. To elucidate the role of chromosome 9 in bladder tumors, it would be interesting to study a possible loss of heterozygosity in this chromosome region.

Carcinoma, Transitional Cell↗
PubMed1993

Appraisal of fluorescence in situ hybridization (FISH) techniques in prenatal diagnosis.

The reliability of FISH was appraised using probes for the X and Y chromosome and for chromosomes 12 and 18 in prenatal and adult interphase nuclei. Detection of a single hybridization spot proved to be quite reliable (80-92% positive nuclei). Detection of two hybridization spots was more difficult; percentages of nuclei showing two signals varied between 62-72%. The percentages of nuclei with the correct number of spots was higher in the metaphases occasionally found. Thus, FISH may complement but not replace cytogenetic analysis. For sex determination and for the detection of mosaicism, we suggest the use of two different probes in separate regions of the same preparation.

Amniotic Fluid↗
PubMed1993

Sephadex filtration and human serum albumin gradients do not select spermatozoa by sex chromosome: a fluorescent in-situ hybridization study.

Fluorescent in-situ hybridization (FISH) of decondensed sperm nuclei has been used directly to evaluate the enrichment efficiency of human sperm separation using Sephadex gel filtration and human serum albumin (HSA) gradients. Control and processed spermatozoa were fixed and their nuclei decondensed. In-situ hybridization was carried out with a Y-specific DNA probe (DYZ1). Sephadex filtration yielded 52.5% Y-chromosome-bearing spermatozoa, HSA separation resulted in 49.4% Y-chromosome-bearing spermatozoa and in the untreated control sample the percentage of Y spermatozoa was 49.3%. Statistical analysis revealed no significant differences between the selection methods employed and the controls, and no real enrichment for X- or Y-bearing spermatozoa was detected for any of the selection methods assayed. The usefulness of the protocols reported for selection of spermatozoa by sex chromosome in couples at risk for X-linked diseases is discussed.

Cell Separation↗