1,720,963 research outputs found
Identification of novel mutations in patients with Shwachman-Diamond syndrome
No full textShwachman-Diamond syndrome (SDS) is a rare autosomal recessive disease, mainly characterized by exocrine pancreatic insufficiency, hematological dysfunction and skeletal abnormalities. The SDS disease locus was mapped to chromosome 7q11 and disease-associated mutations were reported in the Shwachman-Bodian-Diamond syndrome (SBDS) gene. SBDS is a member of a highly conserved protein family with putative orthologs in diverse species including archaea and eukaryotes. It is widely expressed in many tissues and its function is still unknown. In the present study we analyzed the genotype of 15 unrelated Italian SDS patients. After sequencing the whole coding region we were able to complete all genotypes of the SDS patients tested. A total of eleven distinct mutations were identified. The most frequent mutations are due to gene conversion events between SBDS and its unprocessed pseudogene, named SBDSP. We described four new gene conversions involving exon 2 and three novel mutations that are not a result of gene conversion events. In two out of the fifteen cases, the family analysis evidenced an apparently unexpected inheritance of SDS alleles between parents and affected children. In the first case we found a new large gene conversion event, that caused the failure of the amplification of the father's allele and in the second what could be explained as a de novo gene conversion. Both cases have important implications for genetic counseling and molecular genetic analysis. In a disorder caused by gene conversions of variable extension these findings emphasize the necessity of testing patient's parents and the significance of the choice of primers
"Restriction site generating-polymerase chain reaction (RG-PCR) for the probeless detection of hidden genetic variation: application to the study of some common cystic fibrosis mutations."
No full textIn this report we describe the use of a DNA amplification technique in which modified primers introduce a base substitution adjacent to the codon of interest and create an artificial restriction site for the detection of mutations which do not produce or modify a naturally occurring restriction site (restriction site generating-polymerase chain reaction, RG-PCR). RG-PCR was developed and applied to the screening in an Italian population sample of several relatively common cystic fibrosis mutations which are not amenable to analysis with a known restriction endonuclease: G542X, 2869insG, Y913C, N1303K, and 1717-1GA. This method, which allows the identification of virtually any single base change by restriction enzyme analysis and without the need for molecular probes, is rapid and easy to perform. The combined use of RG-PCR for several different CF mutations in multiplex tests further expands the advantages of this approach
"A tetranucleotide repeat polymorphism in the cystic fibrosis gene"
No full textWe describe a tetranucleotide (GATT) repeat polymorphism in the cystic fibrosis transmembrane conductance regulator gene. © 1991, Springer-Verlag. All rights reserved
Cystic fibrosis: the delta F508 mutation does not lead to an exceptionally severe phenotype. A cohort study
No full textIn an attempt to ascertain a relationship between genotype and phenotype, we studied the pulmonary and nutritional status of 123 cystic fibrosis patients with known genotype at an age of 8.5-10 years. Patients represent a cohort as they are almost all those born and diagnosed in a given area and period. They were followed at a single centre using uniform diagnostic and treatment protocols. Pulmonary and nutritional status of homozygous delta 508 patients did not differ from that of compound heterozygotes or of patients with other unspecified genotypes. Pulmonary manifestations varied widely in all genotype groups. With the given number of patients, a slightly higher mortality of delta F508 homozygotes could have been coincidental. We conclude that up to the age of 8.5-10 years the severity of pulmonary lesions and nutritional deficiencies is not related to the delta F508 mutation
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
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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