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Biomedical subjects

M M Pérez

Publications and source records attributed to M M Pérez.

15 recordsLinked to original sources
PubMed2005

Estradiol prevents neural tau hyperphosphorylation characteristic of Alzheimer's disease.

Alzheimer's disease (AD) is three times more prevalent in women than men, and epidemiological studies have shown that estrogen replacement in aging women forestalls the onset of AD. Hyperphosphorylation of the tau protein that forms the neurofibrillary tangles found in AD brains might be responsible for the breakdown of microtubules in affected neurons. The mechanisms by which tau protein is phosphorylated in the AD brain are not fully understood. Using a human neuroblastoma cell line (SH-SY5Y) and primary cultures of newborn male or female rat cerebral cortical neurons, we investigated the effect of 17beta-estradiol on tau protein expression and phosphorylation. We found that estradiol increased total tau and induced dephosphorylation at the proline-directed site of the molecule. Further, estradiol prevented okadaic acid-induced hyperphosphorylation of tau in both proline- and non-proline-directed sites, and antiestrogens blocked this effect. To our knowledge, this is the first report of an effect of estradiol on naturally occurring and induced tau phosphorylation. This assumes special significance because the estrogen action was found to be sexually dimorphic in rat cortical neurons and differentiation-sensitive in human neuroblastoma cells.

Alzheimer Disease↗
PubMed1998

Sperm chromosome analysis in the father of a child with a de-novo reciprocal translocation t(11;15)(q12;q22) by G-banding and fluorescence in-situ hybridization.

Analysis of sperm chromosomes by G-banding and two-colour fluorescence in-situ hybridization (FISH) was carried out in the father of a child with a de-novo reciprocal translocation t(11;15)(q12;q22). Sperm chromosome complements were obtained after in-vitro fusion of zona-free hamster oocytes and donor spermatozoa. A total of 112 sperm complements was first analysed by G-banding. The frequency of structural chromosome aberrations (9.8%) and the conservative frequency of aneuploidy (0.0%) were not significantly different from those obtained in our control donors. The proportions of X-bearing (53.2%) and Y-bearing (46.8%) spermatozoa were not significantly different from the expected 1:1 ratio. A total of 313 sperm complements was analysed by two-colour FISH. The frequency of structural abnormalities for chromosomes 11 and 15 was 3.2 and 0.3% respectively. The frequency of rearrangements for chromosome 11 was statistically significant when compared with control donors (0.4%) (P < 0.0001). No spermatozoa with the t(11;15)(q12;q22) translocation were observed, showing no evidence for a germ-cell mosaicism. These results suggest that the de-novo involvement of chromosome 11 in a structural rearrangement is not random, and that in this patient an increased risk of de-novo structural chromosome abnormalities in further offspring does exist.

Adolescent↗
PubMed1998

Cytogenetic analysis of spermatozoa in the father of a child with a de-novo reciprocal translocation t(7;9) (q22;p23).

Analysis of sperm chromosomes was carried out in the father of a child with a de-novo reciprocal translocation t(7;9) (q22;p23) by G-banding and chromosome painting. Sperm metaphases were obtained using the zona-free hamster oocyte-human sperm fusion technique. A total of 138 complements were sequentially analysed by G-banding and fluorescence in-situ hybridization (FISH). The frequency of spermatozoa with structural chromosome abnormalities (5.1%) and the estimated conservative aneuploidy (1.4%) were within the range obtained in our control donors (6.9 and 4%). The sex ratio (45.3% X versus 54.7% Y) was not significantly different from the theoretical 1:1. A total of 309 sperm complements was analysed by FISH, 138 sequentially analysed by G-banding-FISH and another 171 analysed by FISH only. The frequencies of structural chromosome abnormalities for chromosomes 7 and 9 (0.6 and 0% respectively) were not significantly different from those obtained in our control donors (0.6 and 0.8%). No spermatozoa with the t(7;9) (q22;p23) were observed, showing no evidence for a germ-cell mosaicism. A statistically significant, positive association between sperm breakpoints and fragile sites (P = 0.0225) was observed. However, the coincidence between fragile sites and sperm breaks (80%) was not significantly different from that obtained in our control donors (79.2%). These results suggest that in this case the risk of structural chromosome abnormalities in further offspring is not increased, although an association between fragile sites and sperm chromosome breaks in the father does exist.

Adult↗
PubMed1997

Coexistence of tetrasomy 8 and trisomy 8 in a case with myeloid metaplasia with myelofibrosis.

We present a case of myeloid metaplasia with myelofibrosis (MM/MF), with tetrasomy 8 as the sole cytogenetic abnormality detected by conventional cytogenetic studies. Tetrasomy 8 was also detected by in situ interphase studies and confirmed by chromosome painting in metaphase. To our knowledge, this is the first case of MM/MF with tetrasomy 8. Noteworthy is the association with neurofibromatosis.

Adult↗
PubMed1995

A new case of trisomy 5 as sole cytogenetic anomaly in acute myeloid leukemia.

We present a case of acute myeloid leukemia (AML-M2) with trisomy 5 (+5) as the sole cytogenetic abnormality in a woman previously diagnosed with schizophrenia. To date, only two cases of AML (other than M2) with +5 as the only change have been reported. Moreover, an association between schizophrenia and partial trisomy of chromosome 5p has been described recently. To our knowledge, this is the first report of AML (subtype-M2) with +5. Noteworthy is the association with schizophrenia.

Chromosomes, Human, Pair 5↗
PubMed1991

Heterochromatin decondensation in chromosomes from chorionic villus samples.

The spontaneous decondensation of constitutive heterochromatic regions of chromosomes 1, 9, 16, and Y has been observed in 46.6 per cent of chorionic villus samples. This type of decondensation is occasionally observed in amniotic fluid cells (9 per cent) and has never been found in fetal lymphocytes. The phenomenon is similar to that described in spermatogonial metaphases, in primary and secondary spermatocytes and in human sperm chromosomes, although decondensation of the heterochromatin of chromosome 15 has never been recorded in chorionic villus samples.

Age Factors↗
PubMed1990

[Prenatal diagnosis of myotonic dystrophy: the first experience in Spain].

We report the first prenatal diagnosis of myotonic dystrophy (MD) in Spain by DNA techniques. The previous familiar study allowed us to determine the DM haplotype in this family with the following probe/enzyme combinations: p4.1/Msp I, LDR 152/Bgl II, Apo CII/Ban I, Taq I, Bam HI, pSCII/Bgl I. In the tenth week of amenorrhea, a transabdominal biopsy was done to obtain chorionic villi. One part of the sample was processed for the cytogenetic analysis that revealed a 46 XY karyotype. The other part was used to perform the molecular analysis with two probes, p4.1 and LDR 152, determining that the fetus was a DM gene carrier with a 96% probability.

Family Health↗
PubMed1990

Karyotype screening of potential sperm donors for artificial insemination.

Cytogenetic studies were carried out in 100 potential semen donors for artificial insemination (AI) before they underwent the routine procedures for acceptance or rejection into the programme, namely medical history, physical examination and blood and semen analyses. Results were only compared at the end of the study. In 80 cases, the karyotype was normal; 12 males showed polymorphic chromosome variants; seven had pericentric inversions of heterochromatic regions; one had a short inversion of chromosome 2; and in one case centromere fragility was observed. Six of the 12 males with normal variants were accepted into the programme and four of them had fathered from one to 13 normal children at the end of the study; the other six had been rejected, four of them because of abnormal seminograms, and another two because the motility control of the frozen semen was negative. Of the seven males with pericentric inversions, one dropped out of the programme; four were accepted and three of them had produced from two to five normal children at the end of the study; two had been rejected due to abnormal seminograms. The individual with centromere fragility was accepted and had produced four normal children at the end of the series. Our conclusion is that although cytogenetic studies of potential donors for AI would be desirable, routine screening for chromosome anomalies is not justified at present.

Genetic Testing↗
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↗
PubMedDate not supplied

Innovative new concepts in augmentative breast surgery.

The female breast is seen as a badge of feminine beauty in our society. While it can vary over time and with fashions, the perfect breast will always be symmetrically balanced and proportionate to the rest of the body. To create an aesthetic and symmetrically balanced breast using implants to enhance them is not an easy task. Surgery must combine the concepts of an ideal breast with the desires of the patient in terms of size. The satisfactory breast should remain soft, well positioned, and mobile to respond to gravity and postural changes. In attempting to construct an "ideal breast," certain basic aesthetic anatomical proportions should be taken into account: natural positioning of the breast in the thorax; symmetry; the position of the nipple-areola complex as the focal point of the breast in the frontal view; a side profile of the breast with a natural soft fall; and, overall, the position of the new inframammary crease in the standing position, while lying down, and while moving.

Adolescent↗
PubMedDate not supplied

Spontaneous chromosome fragility in chorionic villus cells.

Human fragile sites are only very rarely expressed spontaneously. In this paper we report the presence of non-random spontaneous chromosome lesions (CL) in chorionic villus samples and their coincidence with fragile site (FS) bands. The average number of CL was about 9% both in RPMI-1640 and in Chang media. To determine any possible influence of external factors other than culture media, the results were grouped according to age of gestation. No differences were observed among the different groups. A total of 101 chromosome lesions could be precisely identified by sequential Leishman Staining/Wright G-banding; 76.2% of them coincided with FS-bands. The most affected region was at 1q12-1q21.1 (15.8% of total CL); other FS with a clustering of breakpoints in our study were 1p36, 1q44, 2q37, 3p24, 3q27, 10q22 and 16q23. These results suggest that spontaneous expression of some FS could be a characteristic of embryonic tissues.

Cells, Cultured↗
PubMedDate not supplied

Prenatal diagnosis in Rett syndrome.

BACKGROUND/AIM: Rett syndrome (RTT) is an X-linked neurodevelopmental dominant disorder that affects almost exclusively girls. The disease is mainly sporadic, caused by de novo mutations at MECP2 gene (Xq28), but a low percentage of familial cases have been reported. We present the results of RTT prenatal diagnosis in three families and discuss the usefulness of such analyses in diseases caused mainly by de novo mutations. METHODS: For adult individuals, DNA was extracted from peripheral lymphocytes; for fetus analysis it was obtained from cultured amniotic fluid or from chorionic biopsy specimens. Mutation detection at MECP2 gene was first carried out in the patients by SSCP/HD analysis and subsequent sequencing. Family studies and prenatal diagnoses were done by direct analysis of previously characterized patients' mutations using SSCP/HD or restriction analysis. RESULTS: Heterozygous mutations identified in the 3 patients were: 1061del96bp, 473C-->T, and 763C-->T, respectively. Mutations were not present in the mothers' DNAs obtained from peripheral lymphocytes. None of the 3 fetuses analyzed carried the mutation of the affected sister. CONCLUSIONS: Recurrence within RTT families can be due to asymptomatic nonpenetrant carrier mothers or to parental germinal mosaicism for the MECP2 mutation. Since germline mosaicism can neither be predicted nor detected, families with 1 affected patient whose RTT-causing mutation has been previously identified can benefit from prenatal diagnosis which contributes to a decrease in the recurrence risk in a new pregnancy comparable to that of the normal population.

Chromosomal Proteins, Non-Histone↗