Biomedical subjects

T Escudero

Publications and source records attributed to T Escudero.

13 recordsLinked to original sources

PubMed2002

Possible interchromosomal effect in embryos generated by gametes from translocation carriers.

BACKGROUND: The incidence of abnormal pregnancies in carriers of balanced translocations depends strictly on the chromosomes involved in the translocations. The aim of this study was to verify whether conventional aneuploidy screening could be advantageously combined with preimplantation genetic diagnosis (PGD) for translocations. METHODS: Twenty-eight carriers of Robertsonian and reciprocal translocations underwent 43 PGD cycles; specific probes were used to screen the translocation in 172 embryos generated by 35 cycles; most of these embryos were also screened for chromosomes 13, 16, 18, 21, 22 (n = 166), XY (n = 107), 1 (n = 17) and 15 (n = 88). For the remaining eight cycles (carriers of reciprocal translocations) only the chromosomes involved in common aneuploidy screening were investigated on the 40 embryos generated in vitro. RESULTS: In Robertsonian translocations, the proportion of embryos with abnormalities due to the translocation was 21%, common aneuploidies contributed 31% of total abnormalities, whereas the remaining 36% of embryos had abnormalities due to both types of chromosome. For reciprocal translocations, the chromosomes involved in the translocation were responsible for 65% of total abnormalities; only 6% of the embryos were abnormal for common aneuploidies and 16% carried abnormalities due to both the chromosomes involved in the translocation and those not related to the translocation. CONCLUSIONS: An interchromosomal effect seems to play a role in the case of Robertsonian translocations, where the relevant contribution of aneuploidy exposes the couple to an additional risk of abnormal pregnancy.

Aneuploidy↗

PubMed2001

Preimplantation genetic diagnosis of pericentric inversions.

Inversions are structural chromosome abnormalities that may be associated with infertility, multiple miscarriage and chromosomally unbalanced offspring. Preimplantation genetic diagnosis (PGD) with subtelomeric probes was used to select for transfer only those embryos that were normal or balanced for three pericentric inversions. In contrast to previous protocols the present procedure allows the detection of unbalanced embryos that might arise from U-recombination in the inverted region. Additionally, aneuploidy screening was carried out in two cases by a second round of fluorescent in situ hybridization (FISH) with centromeric probes. Of the three couples that underwent the procedure one became pregnant twice. The first pregnancy delivered a healthy and chromosomally normal baby and the second pregnancy is ongoing with triplets.

Adult↗

PubMed2001

Double locus analysis of chromosome 21 for preimplantation genetic diagnosis of aneuploidy.

Preimplantation genetic diagnosis (PGD) of numerical chromosome abnormalities significantly reduces spontaneous abortions and may increase pregnancy rates in women of advanced maternal age undergoing in vitro fertilization. However, the technique has an error rate of around 10% and trisomy 21 conceptions have occurred after PGD. To further reduce the risk of transferring trisomy 21 embryos to the patient, we designed a protocol that analyzes chromosome 21 twice by targeting two different loci. This protocol was applied to 388 embryos from 60 cycles of PGD of aneuploidy. The scoring criterion used was based on giving equal importance to both probe results. Of the 242 embryos diagnosed as abnormal, 125 were re-biopsied to assess the rate of false positives and false negatives of the protocol and their clinical relevance. The results of the present study showed no reduction in the overall fluorescent in situ hybridization (FISH) error rate for single cells. However, by using a different scoring criterion, the incidence of false negative can be reduced to 1.6% without missing any trisomy 21. In addition, the present study suggests that if two or more loci from the same chromosome could be simultaneously analyzed in single cells, errors caused by false monosomies could be reduced.

Aneuploidy↗

PubMed2000

Analysis of chromosome abnormalities in sperm and embryos from two 45,XY,t(13;14)(q10;q10) carriers.

Robertsonian translocation t(13q14q) is studied in sperm and embryos of two couples undergoing preimplantation genetic diagnosis (PGD) in which both males are carriers of the translocation. It is already known that the chances of achieving pregnancy for a translocation carrier are directly linked to the number of normal or balanced embryos available for replacement. In our work it was found that the frequency of balanced spermatozoa was almost identical in both patients (74 and 77%), and after PGD, the frequencies of abnormal embryos caused by the translocation were also similar. Sperm chromosome analysis in translocation carriers can provide a reasonable basis for estimating a baseline of chromosome abnormalities to be found in embryos during an assisted reproductive cycle. However, individual factors not linked to the translocation can also produce other chromosome abnormalities (mosaicism, haploidy, polyploidy) and may compromise the chances of achieving a viable pregnancy.

Adult↗

PubMed2000

Outcome of preimplantation genetic diagnosis of translocations.

OBJECTIVE: To review 35 cases of preimplantation genetic diagnosis (PGD) of translocations with several methods, including telomeric probes. DESIGN: Retrospective study. SETTING: Clinical IVF laboratory. PATIENT(S): Thirty-five couples with one partner carrying a chromosomal translocation. INTERVENTION(S): PGD of translocation after polar-body or embryo biopsy. MAIN OUTCOME MEASURE(S): Pregnancy outcome. RESULT(S): Several trends were observed. First, PGD can achieve a statistically significant reduction in spontaneous abortion, from 95% to 13%. Second, the chances of achieving pregnancy are correlated with 50% or more of the embryos being chromosomally normal. Third, patients with robertsonian translocations produced fewer abnormal gametes and more pregnancies than did patients with reciprocal translocations. Fourth, a new fluorescence in situ hybridization protocol for PGD of translocations, which involves applying telomeric probes, has proved adequately reliable with a 6% average error rate. CONCLUSION(S): PGD of translocations achieves a statistically significant reduction in spontaneous abortion, both for polar-body and blastomere biopsy cases. Pregnancy outcome depended on the number of normal embryos available for transfer, with patients having <50% abnormal embryos achieving the most pregnancies. Because robertsonian translocations caused fewer abnormal embryos than reciprocal translocations, they also resulted in higher rates of implantation.

Abortion, Spontaneous↗

PubMed2000

Improvements of preimplantation diagnosis of aneuploidy by using microwave hybridization, cell recycling and monocolour labelling of probes.

Recent studies indicate that preimplantation genetic diagnosis of aneuploidy significantly reduces spontaneous abortions and increases pregnancy rates in women of advanced maternal age undergoing in-vitro fertilization. A new protocol was developed involving cell recycling (sequential hybridizations) and microwave hybridization of repetitive probes in order to obtain in a few hours enumeration results for chromosomes X, Y, 1, 13, 15, 16, 18, 21 and 22 in single blastomeres. The error rate using this protocol was significantly lower than in previous protocols and the analysis of nine chromosomes can be achieved in a shorter time than before.

Adult↗

PubMed2000

Gamete segregation in female carriers of Robertsonian translocations.

Eleven female carriers of either 45,XX,der(13;14) (q10;q10) or 45,XX, der(14;21)(q10;q10) underwent hormonal stimulation with the purpose of producing enough oocytes for in-vitro fertilization and preimplantation genetic diagnosis. Polar body biopsy was performed in those oocytes and FISH with painting probes was applied in their metaphase-like first polar body chromosomes. In this way, unbalanced, normal and balanced oocytes could be distinguished and segregation modes ascertained. der(14;21)(q10;q10) produced 42% unbalanced, 37% normal and 21% balanced oocytes (n = 86) while der(13;14)(q10;q10) generated 33% unbalanced, 51% normal and 16% balanced oocytes (n = 69). In both translocations the number of normal oocytes was significantly higher than the number of balanced oocytes. However, while the frequency of unbalanced events involving chromosome 13 and 14 was similar in der(13;14)(q10;q10), there were significantly more abnormalities involving chromosome 21 than 14 in the der(14;21) (q10;q10) cases. When comparing survival rates to term, trisomies from Robertsonian origin seem to survive more often than those originated by non-disjunction in non-translocation carriers. The meiotic segregation patterns found in female Robertsonian translocations are different from those described in male carriers, with higher rates of unbalanced gametes in females than in males.

Aneuploidy↗

PubMed2000

Female gamete segregation in two carriers of translocations involving 2q and 14q.

FISH, using a combination of whole-chromosome painting and telomeric probes, was used to study the gamete segregation of two female carriers of translocations involving the same chromosome arms, 2q and 14q. Preimplantation genetic diagnosis of the first polar bodies of these oocytes permitted selecting normal embryos for replacement.

Abortion, Spontaneous↗

PubMed2000

Current awareness

In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of prenatal diagnosis. Each bibliography is divided into 17 sections: 1 Books, Reviews & Symposia; 2 General Interest; 3 Normal Fetal Development; 4 Gametogenesis and Pre-implantation Diagnosis; 5 First Trimester Diagnosis; 6 Second Trimester Diagnosis; 7 Fetal Diagnosis by Ultrasound and Other Imaging; 8 Maternal Screening; 9 Screening for Carriers of Genetic Abnormality; 10 Technological Developments; 11 Confined Placental Mosaicism and Uniparental Disomy; 12 Molecular Cytogenetics; 13 Fetal Cells in Maternal Circulation; 14 Fetal Therapy; 15 Psychosocial Aspects; 16 Epidemiology and Environmental Factors; 17 Developmental Pathology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted

Journal Article↗

PubMed1999

Follow-up of chimerism in children with hematological diseases after allogeneic hematopoietic progenitor cell transplants.

Using in situ hybridization with an X and Y chromosome probe mixture, 106 bone marrow samples from 38 patients with malignant and non-malignant hematological diseases who received sex-mismatched allogeneic hematopoietic progenitor cell transplants (PCT) in a single institution within short-term intervals (1, 3, 6, 12, 24 and >24 months) have been sequentially studied. The patients received either HLA-identical (n = 31) or non-identical (n = 7) PCT. Twenty-six children showed donor chimerism, 10 children showed mixed chimerism (MC) and two children presented autologous reconstitution. Chimerism status with different parameters has been related (age, sex, donor, disease status before PCT, conditioning regimen, GVHD prophylaxis, relapse, GVHD and survival). Our results indicate that female patients (P = 0.011) and a less intensive conditioning regimen (P = 0.039) are significantly associated with the MC status. Mixed chimerism is not, per se, significantly associated with leukemia relapse but an increase of the MC is indicative of clinical relapse.

Adolescent↗

PubMed1998

Cytogenetic analysis using simultaneous and sequential fluorescence in situ hybridization.

A sequential fluorescence in situ hybridization (FISH) technique is described. This method allows the detection of up to eighteen chromosome pairs in consecutive hybridizations (8 steps) on the same metaphase using centromeric, whole chromosome painting, and single copy DNA probes with different fluorochromes. The technique may be used with diagnostic purposes in cases with poor cytogenetic material.

Cells, Cultured↗

PubMed1997

A case with 47,XXY,del(15)(q11;q13) karyotype associated with Prader-Willi phenotype.

Herein we present the case of a 12-year-old boy who attended our clinic for obesity and hyperphagia. As a newborn he was noted to have diffuse muscular hypotonia and poor sucking response. At the age of 11 years, he was admitted to hospital for respiratory insufficiency. He had personality disorders characterized by temper tantrums and violent outbursts including self-mutilation. Physical evaluation revealed marked central obesity, he had small hands and feet, and also genital hypoplasia. Of the biochemical parameters, hyperglycemia and a low serum testosterone level must be emphasized. The patient fulfills the clinical criteria of typical Prader-Willi syndrome. Cytogenetic and fluorescence in situ hybridization analysis showed a karyotype 47,XXY, del(15)(q11;q13). To our knowledge this is the first report of the aforementioned genotype expressed as Prader-Willi phenotype in childhood.

Child↗

PubMed1989

Quantitative determinations of chemical compounds with nutritional value from Inca crops: Chenopodium quinoa ('quinoa').

Quantitative determinations of total and soluble proteins, total and free sugars, starch, total lipids, tanins, ash (Ca, Na, K, Fe, and P), and caloric value were carried out on quinoa flour. Results show that the amount of soluble proteins was higher than the standard value for wheat and maize and was very close to that of barley's. The yield of free sugars like glucose (4.55%), fructose (2.41%) and sucrose (2.39%) were also of importance. Iron and calcium levels were higher than the reported values for maize and barley. The same occurred for the caloric value (435.5 Kcal/100 g). The content of saponins was also examined since its effect on red blood cells of group A and O has been related as a potential problem of the Andes population. From the chemical analysis a more complete view about quinoa as human food was presented.

Carbohydrates↗