1,720,974 research outputs found
Hereditary neuropathy with liability to pressure palsies and inherited brachial plexus neuropathy--two genetically distinct disorders
No full textTo determine whether hereditary neuropathy with liability to pressure palsies (HNPP) and inherited brachial plexus neuropathy (IBPN) are genetically distinct disorders and to evaluate the usefulness of fluorescence in situ hybridization (FISH) for diagnosing HNPP in individual patients
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Insulin-like growth factor-I prevents apoptosis in neurons after nerve growth factor withdrawal
No full textInsulin-like growth factor-I (IGF-I) is emerging as an important growth factor able to modulate the programmed cell death (PCD) pathway mediated by the cysteine-dependent aspartate proteases (caspases); however, little is known about the effect of IGF-I after nerve growth factor (NGF) withdrawal in neurons. To begin to understand the neuronal death-sparing effect of IGF-I under NGF-free conditions, we tested whether embryonic sensory dorsal root ganglion neurons (DRG) were able to survive in defined serum-free medium in the presence of IGF-I. We further studied the role of IGF-I signaling and caspase inhibition after NGF withdrawal. NGF withdrawal produced histological changes of apoptosis including chromatin condensation, shrinkage of the perikaryon and nucleus, retention of the plasma membrane, and deletion of single cells. Both IGF-I and Boc-aspartyl (OMe)-fluoromethylketone (BAF), a caspase inhibitor, equally reduced apoptosis after NGF withdrawal. The antiapoptotic effect of IGF-I was completely blocked by LY294002, an inhibitor of PI 3-kinase signaling, but not by the mitogen-activated protein (MAP) kinase/extracellular signal-regulated protein kinase (ERK) activated protein kinase inhibitor PD98059. Functional IGF-I receptors were extensively expressed both in rat and human DRG neurons, although they were most abundant in the neuronal growth cone. Collectively, these findings indicate that IGF-I, signaling though the PI-3 kinase pathway, is important in modulating PCD in cultured DRG neurons after NGF withdrawal, and IGF-I may be important in DRG embryogenesis
Variations on the Author
Get PDF“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
Get PDFWe 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
Insulin-like growth factor-II as a paracrine growth factor in human neuroblastoma cells
No full textThe human neuroblastoma line, SK-N-SH, has been subcloned into SH-SY5Y, a neuroblast N cell line, and SH-EP, an epithelial Schwann S cell line. We have previously shown that SH-SY5Y neuroblastoma cells produce insulin-like growth factor II (IGF-II), which acts by an autocrine mechanism to stimulate cell growth. In the current study, we examined the effect of IGF-II on SH-EP neuroblastoma cells. Northern blot and reverse transcriptase-polymerase chain reaction analyses indicate that SH-EP cells do not produce IGF-I or IGF-II but express the type I and type II IGF receptors (IGF-IR and IGF-IIR). Cell surface expression of IGF-IR, assessed by fluorescence-activated sorting, was lower in SH-EP cells than in SH-SY5Y cells. Immunoprecipitation of IGF-IR, followed by anti-phosphotyrosine or anti-IGF-IR immunoblotting, demonstrated functional expression of these receptors in both cell types and confirmed the lower level of IGF-IR expression in SH-EP cells. IGF-II promoted SH-EP cell growth in the presence of low concentrations of calf serum (0.1-0.3%) or 10 ng/ml epidermal growth factor (EGF). IGF-II stimulation of SH-EP growth was eliminated by the IGF-IR blocking antibody (alpha IR-3) but not by an IGF-IIR blocking antibody. Stimulation of cell growth via this receptor was also indicated by the ligand specificity for IGF analogs and insulin (IGF-II approximately IGF-I approximately des(1-3)IGF-I > insulin). These results indicate that in the presence of a permissive factor such as calf serum or EGF, IGF-II stimulates SH-EP cell growth via the IGF-IR. Collectively, these data suggest that within primary neuroblastomas, IGF-II may act as a paracrine factor to contribute to the promotion of S cell growth
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Autocrine regulation of neurite outgrowth from PC12 cells by nerve growth factor
No full textThe PC12 cell line may be used as a model of NGF-induced neuronal differentiation. Exposure to NGF is accompanied by extension of neurites, cessation of growth and differentiation into cells resembling sympathetic neurons. In this study neurite outgrowth from PC12 cells was induced in serum-free, NGF-free medium conditions. Neurite outgrowth in serum-free conditions was abolished by exposure to anti-NGF antisera. Reverse transcription combined with polymerase chain reaction (RT-PCR) and in situ hybridization of PC12 cells in serum-free medium conditions revealed NGF transcripts. Western blot analysis of these cells revealed tyrosine phosphorylation of the high affinity NGF receptor (TrkA/gp140) and activation of a downstream signal cascade element, ERK-1/MAP kinase. NGF was also detected by a specific enzyme-linked immunoabsorbant assay (ELISA) revealing picogram levels of protein in conditioned medium and cell lysates. Survival of embryonic rat dorsal root ganglion neurons was maintained in cultures grown in this serum-free conditioned medium. This demonstrated that NGF may act as an autocrine or paracrine growth factor for PC12 cell differentiation
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