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UCL University College London Eprints (372,926 recursos)

UCL Eprints collects the work of UCL researchers and makes it freely available over the web, helping the worldwide scholarly community to discover UCL research. Institutional repositories like UCL Eprints complement the traditional academic publishing and scholarly communications processes. They raise the visibility of research and help to maximise its impact. UCL researchers are encouraged to deposit a copy of each journal article, conference paper, working paper, and any other research output, in the UCL Eprints at the earliest opportunity, ensuring that their research reaches as wide an audience as possible.

Mostrando recursos 181 - 200 de 376,750

  1. Increased susceptibility to maternal aneuploidy demonstrated by comparative genomic hybridization analysis of human MII oocytes and first polar bodies.

    Fragouli, E; Wells, D; Whalley, KM; Mills, JA; Faed, MJ; Delhanty, JD
    Single cell comparative genomic hybridization (CGH) was employed to extensively investigate 24 unfertilized or in vitromatured meiosis II oocytes and their corresponding first polar bodies (PBs), to determine how and whether all 23 chromosomes participate in female meiosis I errors and to accurately estimate the aneuploidy rate in the examined cells. Results were obtained for 15 oocytes and 16 PBs, representing 23 eggs (MII oocyte-PB complexes) donated from 15 patients (average age 32.2 years). Abnormalities were detected in ten eggs, giving an overall aneuploidy rate of 43.5%. In all, fourteen anomalies were scored, with the fertilized oocyte being at risk...

  2. Single cell diagnosis using comparative genomic hybridization after preliminary DNA amplification still needs more tweaking: too many miscalls.

    Fragouli, E; Delhanty, JD; Wells, D

  3. What are the issues surrounding preimplantation genetic diagnosis for late-onset disorders?

    Delhanty, J

  4. Mechanisms of aneuploidy induction in human oogenesis and early embryogenesis.

    Delhanty, JD
    The mechanisms of aneuploidy induction in human oogenesis mainly involve nondisjunction arising during the first and second meiotic divisions. Nondisjunction equally affects both whole chromosomes and chromatids, in the latter case it is facilitated by "predivision" or precocious centromere division. Karyotyping and CGH studies show an excess of hypohaploidy, which is confirmed in studies of preimplantation embryos, providing evidence in favour of anaphase lag as a mechanism. Preferential involvement of the smaller autosomes has been clearly shown but the largest chromosomes are also abnormal in many cases. Overall, the rate of chromosomal imbalance in oocytes from women aged between 30...

  5. Genetics of gametes and embryos.

    Harper, JC; Pergament, E; Delhanty, JD
    Chromosome analysis of oocytes, sperm and embryos has mainly relied on fluorescent in situ hybridisation (FISH) and karyotyping. FISH studies have been performed on sperm from fertile and infertile men as well as men carrying known chromosomal translocations. Molecular DNA analyses has aided in the identification and treatment of men with Y chromosome deletions. In oocytes FISH and karyotyping have identified non-disjunction of univalents and predivision of chromatids. Analysis of the chromosomes from human embryos has shown that a high proportion of embryos are mosaic or chaotic, in addition to embryos beings uniformly and abnormal. FISH and PCR have also...

  6. Mechanisms of aneuploidy induction in human oogenesis and early embryogenesis

    Delhanty, JDA

  7. Preimplantation genetic diagnosis of chromosome abnormalities: implications from the outcome for couples with chromosomal rearrangements

    Simopoulou, M; Harper, JC; Fragouli, E; Mantzouratou, A; Speyer, BE; Serhal, P; Ranieri, DM; Doshi, A; Henderson, J; Rodeck, CH; Delhanty, JDA
    Objectives Chromosomal rearrangements can lead to infertility or repeated spontaneous or induced abortions. The use of preimplantation genetic diagnosis (PGD) allows the selected transfer of chromosomally balanced embryos. The aim of this study was to carry out detailed analysis of the outcome of I I PGD cycles for 8 patients carrying various chromosomal rearrangements.Methods Patients underwent routine in vitro fertilisation with biopsy of embryos on day 3. Specific fluorescent in situ hybridisation protocols were developed for each couple. Embryo transfer was possible in all I I cycles.Results The outcome was four pregnancies, leading to three live births and one biochemical...

  8. Beta thalassaemia: fetal HLA typing.

    Delhanty, JD

  9. A novel, de novo germline TP53 mutation in a rare presentation of the Li-Fraumeni syndrome in the maxilla

    Patrikidou, A; Bennett, J; Abou-Sleiman, P; Delhanty, JDA; Harris, M
    We undertook the genetic analysis of a classic Li-Fraumeni syndrome (LFS) family with clustering of primary tumours including two maxillary sarcomas, a rare LFS site of tumour occurrence. Our aim was to investigate the presence of a specific type of TP53 mutation that could be associated with this unusual predilection of site for cancer occurrence.Mutational screening of the coding region of TP53 revealed an A > T transversion in codon 144 of exon 5 (CAG > CTG, Gln > Leu) in the germline of one of the three affected members, with loss of heterozygosity (LOH) in the tumour tissue. All...

  10. β thalassaemia: Fetal HLA typing

    Delhanty, JDA

  11. Preimplantation genetics: an explanation for poor human fertility?

    Delhanty, JD

  12. A successful strategy for preimplantation genetic diagnosis of myotonic dystrophy using multiplex fluorescent PCR

    Piyamongkol, W; Harper, JC; Sherlock, JK; Doshi, A; Serhal, PF; Delhanty, JDA; Wells, D
    The most common form of inherited muscular dystrophy in adults is myotonic dystrophy (DM), an autosomal-dominant disease caused by the expansion of an unstable CTG repeat sequence in the 3′ untranslated region of the myotonin protein kinase (DMPK) gene. Expanded (mutant) CTG repeat sequences are refractory to conventional PCR, but alleles with a number of repeats within the normal range can be readily amplified and detected. Preimplantation genetic diagnosis (PGD) of DM has been successfully applied. However, a misdiagnosis using the reported protocol was recently documented. Two new PGD protocols for DM have been developed which utilise multiplex fluorescent PCR....

  13. A successful strategy for preimplantation diagnosis of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency

    Ioulianos, A; Wells, D; Harper, JC; Delhanty, JDA
    Preimplantation genetic diagnosis (PGD) involves the screening of biopsied cells from in vitro fertilization (IVF) generated embryos. This procedure allows the selective transfer of unaffected embryos and thus may be preferable to prenatal diagnosis for couples at high risk of transmitting genetic defects to their offspring. In this way, termination of pregnancy is avoided. We describe here the development and first clinical application of PGD for medium-chain acyl-CoA dehydrogenase deficiency (MCAD). MCAD is a common inherited metabolic disorder affecting fatty acid β oxidation. The condition is autosomal recessive with an incidence of 1/6000 1/15,000 live births in the UK. It...

  14. Comparative genomic hybridization reveals extensive variation among different MCF-7 cell stocks

    Jones, C; Payne, J; Wells, D; Delhanty, JDA; Lakhani, SR; Kortenkamp, A
    Comparative genomic hybridization (CGH) allows the detection of DNA sequence copy number changes on a genome-wide scale in ct single hybridization reaction. The ability of CGH to be applied to formalin;fixed, paraffin-embedded tumor samples has lead to its widespread application in the cytogenetic analysis of archival material. When setting up CGH in the laboratory, rigorous control experiments must be carried out to ensure that the losses and gains are scored correctly. Groups interested in breast cancer frequently use the MCF-7 cell line as a positive control in these experiments, comparing the results to previously described genetic alterations. Here we present...

  15. PGD protocols using multiplex fluorescent PCR.

    Piyamongkol, W; Harper, JC; Delhanty, JD; Wells, D

  16. Guest editorial.

    Harper, JC; Pergament, E; Delhanty, JD

  17. Single cell detection of inherited retinoblastoma predisposition.

    Sütterlin, M; Sleiman, PA; Onadim, Z; Delhanty, J
    Retinoblastoma susceptibility is an autosomal dominantly inherited cancer predisposition which also confers a life-long increased risk for various non-ocular malignancies. We developed a protocol for single cell detection of this disorder which enables its preimplantation genetic diagnosis as an alternative to prenatal diagnosis with attendant pregnancy termination. The presented method detects the underlying mutation of the disease, a linked intragenic polymorphism (p88PR0.6) and an independent marker (D21S1411) for genetic fingerprinting allowing detection of contamination. The strategy is based on the combination of nested triplex polymerase chain reaction, single strand conformation polymorphism analysis by conventional polyacrylamide gel electrophoresis and fragment size...

  18. Guest editorial

    Harper, J; Pergament, E; Delhanty, J

  19. Chromosome analysis by FISH in human preimplantation genetics.

    Delhanty, JD

  20. Preimplantation diagnosis: Basic science and clinical practice

    Delhanty, JDA
    Preimplantation genetic diagnosis (PGD) was first carried out in the UK, at the Hammersmith Hospital, in 1989. Since then almost 100 babies have been born worldwide following PGD with no reported increase in congenital anomalies. This overview will consider the types of patients coming forward for the procedure, approaches to single cell diagnosis and the technical difficulties that have become apparent.

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