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Biomedical subjects

J Benet

Publications and source records attributed to J Benet.

At least 55 records · Page 3Linked to original sources
PubMed1990

Meiotic and sperm chromosome studies in a reciprocal translocation t(1;2)(q32;q36).

Meiotic and sperm chromosomes were studied in a man heterozygous for a reciprocal translocation t(1;2)(q32;q36). Forty-five meiotic metaphase I cells were obtained from semen samples: 86.6% were 22,XY,IV and 13.3% had synaptic anomalies that affected all or some of the bivalents. The quadrivalents observed had a ring configuration (92.3%) or a chain configuration (7.7%). A total of 105 sperm chromosome complements were analyzed: 41% resulted from an alternate segregation, and the percentage of unbalanced sperm was 59%; most of them (71%) resulted from an adjacent 1 segregation. The frequency of anomalies unrelated to the translocation (5.7% numerical and 14.1% structural anomalies) were within the normal range for control donors. There was a good correspondence between the percentage of cells with a ring IV (92.3%) and the proportion of 2:2 segregations (88.6%) and between the percentage of chain IV (7.7%) and the incidence of 3:1 segregations (11.4%).

Chromosomes, Human, Pair 1↗
PubMed1990

Human sperm chromosomes. Long-term effect of cancer treatment.

The long-term cytogenetic effect of radio- or chemotherapy or both on male germ cells was evaluated by study of the chromosomal abnormalities in spermatozoa of four men treated for cancer 5-18 years earlier. The cytogenetic analysis of 422 sperm metaphases showed no differences in the aneuploidy rate. The incidence of structural chromosome aberrations was 14.0%, however, which is much higher than in controls. Thus, the high incidence of structurally aberrant spermatozoa observed in our long-term study indicates that antitumoral treatments affect stem-cell spermatogonia and that aberrant cells can survive germinal selection and produce abnormal spermatozoa.

Antineoplastic Agents↗
PubMed1990

Sperm chromosome studies in an infertile man with partial, complete asynapsis of meiotic bivalents.

Meiotic and sperm chromosome studies were carried out in two semen samples from an infertile man with a 46,XY karyotype, oligoasthenoteratozoospermia and abundant exfoliation of spermatogenic cells. Meiotic preparations showed partial, complete asynapsis in a large proportion of metaphase I figures observed, and absence of metaphase II figures, while 24 of the 30 sperm chromosome karyotypes analysed were normal. The remaining sperm karyotypes were as follows: one with structural abnormalities, one with both structural abnormalities and hypohaploidy and four with hypohaploidy. The total frequency of chromosomal abnormalities (6.7%) is similar to that obtained by us in normal men (10.9%). The frequency of spermatozoa with structural abnormalities (6.7%) was not significantly different from that obtained by us in normal men (6.9%). These results suggest that, in some cases, asynaptic spermatogenic cells do not proceed further than metaphase I and only normal germ cells continue spermatogenesis.

Adult↗
PubMed1990

Sperm chromosome studies in individuals treated for testicular cancer.

Sperm chromosome studies have shown that patients treated with chemotherapy for testicular cancer have a much higher incidence of chromosome abnormalities than patients treated for other types of cancer or than controls. In two out of four cases, penetration of zona-free hamster eggs was close to zero, indicating that after 2-7 years after treatment the functional capacity of the sperm had not been recuperated. The cytogenetic study of the spermatozoa shows that many of the abnormalities observed corresponded to structural aberrations that may not have a pathogenic effect in the production of abortions or of children with chromosome abnormalities.

Adult↗
PubMed1989

Expression of fragile sites in human sperm and lymphocyte chromosomes.

Sperm and lymphocyte chromosome studies in a normal, fertile male have shown a high degree of coincidence between chromosome lesions and fragile sites in both types of cells. In this donor we also found that some fragile sites expressed in sperm chromosomes coincided with those expressed in lymphocyte chromosomes. These results indicate that the chromosome lesions expressed in sperm do not occur at random and that they are not technical artifacts. The fragility expression in sperm chromosomes could reflect in vivo conditions. The presence in some sperm metaphases of acentric fragments suggests that chromosome fragility can result in the loss of chromosome fragments or give rise to de novo structural rearrangements. However, the incidence of sperm with chromosomal abnormalities observed in this man was within the normal range.

Adult↗
PubMed1988

Human sperm chromosome studies in a reciprocal translocation t(2;5).

Sperm chromosome complements have been studied in a man heterozygous for a reciprocal translocation t(2;5)(p11;q15). Human sperm chromosomes were obtained after fertilization of zona-free hamster eggs. A total of 75 human sperm metaphases were analysed. On the complements studied, 59 (78.6%) resulted from a 2:2 segregation and 16 (21.3%) from a 3:1 segregation, 4:0 segregation was not observed. Our results indicate that at least 36% of sperm complements were unbalanced with respect to the translocation. The frequency of other chromosome anomalies unrelated to the translocation was 16%.

Adult↗
PubMed1988

Sperm chromosome complements in a 47,XYY man.

Human sperm chromosomes from a 47,XYY male were examined using the direct method of sperm chromosome analysis with two modifications in the semen processing. A total of 75 sperm complements was karyotyped and all of these contained one sex chromosome. The percentages of X- and Y-bearing sperm were 53% and 47%, respectively. There were 10 sperm with autosomal chromosomal abnormalities. The frequencies of numerical (4.0%), structural (10.6%), and total (13.3%) abnormalities were not significantly different from the frequencies observed in normal donors in our laboratory. Our results do not support the suggestion that XYY males have an increased risk of aneuploid progeny as a result of secondary non-disjunction or interchromosomal effects. They do support the hypothesis that one Y chromosome is eliminated in the germ cells of XYY males. However since our study provides the first information on sperm chromosomes in an XYY male, further studies on other XYY men are required.

Abortion, Habitual↗
PubMed1988

Human sperm chromosomes.

Sperm chromosome studies have been performed in 70 normal males. The incidence of aneuploidy in this group is approximately 3-4%, and that of structural anomalies close to 5%. In carriers of reciprocal or Robertsonian translocations, the results are extremely variable, with percentages of unbalanced sperm from 8 to 87%. No unbalanced spermatozoa have been observed in patients with pericentric or paracentric inversions. In cancer patients treated with radio and/or chemotherapy, the incidence of chromosome abnormalities is much higher, and significantly different from that found in controls.

Aneuploidy↗
PubMed1987

Expression of a possible constitutional "hot spot" in sperm chromosomes of a patient treated for Wilms' tumor.

Sperm chromosomes were studied in a man who was treated for Wilms' tumor with radiotherapy (RT) and chemotherapy (CT) 18 years ago. Human pronuclear sperm chromosomes were obtained after penetration of zona-free hamster eggs. Eighty-nine sperm chromosome complements were analyzed; 12.4% of them showed structural anomalies. This percentage was statistically different from the one found in our laboratory for controls (p less than 0.05). Five of eleven structurally abnormal metaphases had the same aberration: fission of chromosome #1 with the breakpoint at or near the centromere. Breaks and rearrangements of chromosome #1, often involving the centromere region, are among the most frequent anomalies found in Wilms' tumor cells.

Adult↗
PubMed1987

Improvement of sperm quality in abnormal semen samples using a modified swim-up procedure.

A modified swim-up procedure for the selection of motile and morphologically normal spermatozoa is described. Applied to abnormal (astheno and asthenoterato) semen samples, the recovery figures are comparable to those obtained by other authors in normal samples. The elimination of seminal plasma from the beginning of the procedure avoids contact of spermatozoa with decapacitating factors.

Cell Separation↗
PubMed1987

Study of human sperm chromosomes by sequential transmission and scanning electron microscopy.

We describe a method of observing human sperm metaphases by sequential transmission and scanning electron microscopy. This permits the analysis of ultrastructural aspects of sperm chromosomes and allows the relationship between ultrastructure, heterochromatin condensation, and the behaviour and staining properties of sperm chromosomes and heterochromatic regions to be determined.

Centromere↗
PubMed1986

G-banding of human sperm chromosomes.

G-banded human sperm chromosomes are routinely obtained in our laboratory using a modification of the method described by Martin et al. (1982). The study of banded sperm chromosomes is essential for the genetic counseling of male carriers of balanced chromosome rearrangements.

Chromosome Banding↗
PubMed1986

Meiotic chromosome studies and synaptonemal complex analyses by light and electron microscopy in 47 infertile or sterile males.

Mitotic and meiotic chromosome studies and synaptonemal complex analyses by light and electron microscopy have been carried out in a selected series of 47 infertile or sterile males with highly abnormal seminograms, affecting the number of spermatozoa, their morphology and/or motility. In 46 cases, the karyotype was 46,XY. One patient had a 13/14 translocation. With the exception of the patient with a 13/14 translocation, and three patients with desynapsis (8.5%), all other cases showed either normal or absent metaphase I figures. However, synaptonemal complex analysis by light and electron microscopy demonstrated the presence of pairing anomalies (desynapsis, fragmented or irregular synaptonemal complexes) in 31.9% of the patients studied. The total number of synaptic anomalies observed (40.4%) is higher than in a former light microscopy study of 111 infertile or sterile patients (28.8%) probably because the higher resolution of the electron microscope permits the characterization of some anomalies that cannot be detected with the light microscope. The electron microscope should therefore be used in all cases in which the light microscope provides doubtful results.

Chromosomes, Human↗