1,721,010 research outputs found
47,XX + mar karyotype containing genes from the azoospermia factor region. A case report
No full textBACKGROUND:
Abnormal embryo development is the major cause of implantation failure and accounts for the low rate of human fertility in vitro and in vivo. Chromosome abnormalities are widely involved in this process through meiotic nondisjunction, fertilization abnormalities and mitotic nondisjunction.
CASE:
In our assisted reproductive technology program a couple underwent cytogenetic analysis. The woman had a 47,XX + mar karyotype. We investigated this patient by chromosome analysis, fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) DNA analysis. The marker chromosome was found to be very similar to a Y chromosome in size and QFQ staining pattern. Therefore, it was tested by FISH using alpha- and beta-satellite DNA specific for the Y chromosome, some YACs specific for the long arm of the Y chromosome and alpha-satellite DNA specific for 15 chromosomes as probes. In order to define this marker, the next step was PCR amplification of the whole genomic DNA using specific landmarks (sequence-tagged sites) to encompass the azoospermia factor (AZF) region on the long arm of the Y chromosome.
CONCLUSION:
A woman had an extra chromosome containing centromeric DNA derived from the Y and 15 other chromosomes, heterochromatic regions derived from 15 chromosomes and a large heterochromatic block at the end of the long arm that definitely was not Y chromosome heterochromatin (beta-satellite). PCR showed several genes of the Y chromosome long arm that are assumed to be involved in male gametogenesis. Phenotypic effects could not be excluded because of the presence of AZF genes. Oocyte karyotyping might better explain the role of the genetic problem on female infertility
Chromosome analysis of spontaneous abortions after in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI).
No full textAutosomal Recessive Bestrophinopahty: new Observations on the Retinal Phenotype. Clinical and Molecular Report of an Italian Family
No full textPURPOSE:
To describe the genotype and phenotype in a 9-year-old boy with bilateral retinopathy.
METHODS:
The patient, his healthy (by history) nonconsanguineous parents and his sister were examined by best-corrected visual acuity, matrix frequency doubling technology, monocular static field analysis, fundus autofluorescence imaging, optical coherence tomography, Ganzfeld electroretinography (ERG), pattern ERG, multifocal ERG, electro-oculography and genotyping of the BEST1 gene.
RESULTS:
The patient presented with an Arden ratio of 1.25, an unremarkable ERG and fluorescent yellow deposits distributed throughout the fundus suggestive of autosomal recessive bestrophinopathy (ARB). Genotyping revealed a homozygous nonsense mutation in BEST1 (p.R200X). The parents and the sister, who were heterozygous mutation carriers, presented with normal ophthalmological function.
CONCLUSIONS:
ARB is a rare retinal disorder. We contribute a novel patient report indicative of ARB, assessed by clinical examination and confirmed by genotyping of BEST1, to the short list of ARB cases in the literature
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Breakpoint of a Y chromosome pericentric inversion in the DAZ gene area. A case report.
No full textAbstract
BACKGROUND:
The presence of a spermatogenesis locus (gene or gene complex) in the euchromatic region of the long arm of the Y chromosome (Yq11), defined as azoospermia factor on the basis of gross structural rearrangement, was detected. The gene family responsible for different spermatogenetic defects is "deleted in azoospermia" (DAZ).
CASE:
A 34-year-old man had oligozoospermia, and a cytogenetic analysis carried out on peripheral lymphocytes with G banding revealed a 46,X, inv(Y)(p11q11)karyotype. The relation between the chromosomal breakpoint and the DAZ gene was more precisely defined by a fluorescent in situ hybridization technique. We revealed two signals for the DAZ gene, weaker than normal, one on the short arm and the other on the long arm of the Y chromosome, indicating that the breakpoint was located at the DAZ gene level.
CONCLUSION:
This is the first report documenting a chromosomal pericentric inversion with disruption in the DAZ gene area. We hope to obtain information on whether the disruption affects a functional zone of the gene and correlates with oligospermia at the chromosomal level
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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