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C Templado

Publications and source records attributed to C Templado.

At least 37 records · Page 2Linked to original sources
PubMed1989

Fragile sites and breakpoints in constitutional rearrangements and in human sperm chromosomes.

Recently, it has been suggested that an association exists between breakpoints involved in constitutional rearrangements and fragile sites; however, statistical analyses of this relationship are controversial. We have analyzed 1200 breakpoint from different constitutional rearrangements, 1522 breakpoints with respect to their recurrence and 217 breakpoints from sperm chromosomes as reported by several authors. The coincidence between breakpoints and fragile sites was 35.3%, 43.6% and 41.9% respectively. The statistical significance of these coincidences depends on whether factors such as the relative length of the bands or the recurrence of the rearrangements are taken into account.

Chromosome Aberrations↗
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↗
PubMed1989

Expression of folate-sensitive fragile sites in lymphocyte chromosomes.

The expression of folate-sensitive fragile sites (FS) was analyzed using MTX as a fragility inducer in seven normal subjects [four unrelated persons and three members of one family (father, mother, and son)]; a woman heterozygous for fra Xq27.3 with a 47,XXX karyotype; and her son, affected by the fra-X syndrome. The mean expression of chromosome lesions (CL) other than Xq27.3 was 70.1% (686CL in 978 metaphases), and the coincidence between CL and FS was 68.9%. We propose six new c-fra sites: bands 4q33 and 11q22 because they were found in two members of the same family; band 13q32 because it had a frequency of expression of 3% of metaphases; and bands 3p13, 8q21, and Xq21 because they were observed in four of the nine individuals studied.

Adult↗
PubMed1988

Can sister chromatid intercrossings be considered as prelesions?

In a study of the expression of folate-sensitive fragile sites in five normal individuals using RPMI medium containing methotrexate (MTX), we observed a high frequency of "sister chromatid intercrossings" (SCI) that is, the intersection of sister chromatids. The location of SCIs corresponded to fragile sites in 54.2% of the cases. Of the SCIs observed in each individual, 43%-53% were located at the same bands as their expressed fragile sites. Furthermore when RPMI + MTX medium was used instead of F-10 medium, the incidence of SCIs increased tenfold. We suggest that SCIs could indicate the existence of a pre-lesion.

Cells, Cultured↗
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

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

Synaptonemal complex studies in the male.

Observations in synaptemal complexes in men carrying structural or numerical chromosomal anomalies are reviewed. Chromosome pairing in patients with extra chromosomes, Robertsonian translocations, reciprocal translocations and pericentric inversions is described. Synaptic anomalies in patients with abnormal seminograms, homosynapsis, asynapsis and heterosynapsis and other pairing abnormalities are also discussed.

Chromosome Aberrations↗
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↗
PubMed1984

Meiotic studies and synaptonemal complex analysis in two infertile males with a 13/14 balanced translocation.

Meiotic and synaptonemal complex studies by light and electron microscopy have been carried out in two infertile males with a balanced 13/14 translocation. As expected, all metaphase I figures in conventional meiotic preparations contained a chain trivalent. Synaptonemal complex studies showed typical trivalent images with incomplete pairing of the acrocentric elements in the cis configuration. A review of the literature shows that the fertility of these patients is quite variable. All of them show a slightly reduced number of chiasmata (mean 46.6). Pairing in cis, as detected by electron microscopic studies, does not seem to have a prognostic value.

Adult↗