130,766 research outputs found
Nongenomic Actions of Thyroid Hormones
No full textNongenomic actions of thyroid hormone do not require a direct interaction of
3,5,30-triiodo-L-thyronine (T3) with the transcriptionally active nuclear receptors
TRα and TRβ. A rapid response time is a characteristic of many nongenomic
actions; the onset of the majority of these effects is within minutes because the
action is independent of gene expression and protein synthesis. While only T3 is
able to generate a genomic response, the different nongenomic effects may be
activated by either T3 or T4 or by other iodothyronine derivatives such as T2. In
the last decade, the discovery of a large number of nongenomic actions of thyroid
hormones has increasingly attracted the interest of researchers, and different
specific binding sites or receptors for these hormones/messengers have now
been described in several cellular compartments, including the external surface
of the plasma membrane. The function of nongenomic effects of these hormones
has mainly been considered to relate to homeostasis, such as actions on plasma
membrane ion transporters or maintenance of the cytoskeleton, but recent evidence
supports the existence of crosstalk between nongenomic and genomic
effects of the hormone. Further examination of such crosstalk may reveal hitherto
unappreciated mechanisms underlying global illnesses, such as cardiovascular
diseases, inflammatory and immune diseases, and mechanisms of tumor cell
function. Indeed, these new aspects have already improved our understanding
of the contributions of nongenomic thyroid hormone actions to the regulation of
cancer-related angiogenesis and to cancer cell survival pathways. In the present
report, we provide a concise overview of the main observations that define the
nongenomic actions of thyroid hormones and give a description of the state of
the art
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Platelet-derived growth factor increases the activity of the promoter of the insulin-like growth factor-1 (IGF-1) receptor gene.
No full textStimulation by platelet-derived growth factor (PDGF) is known to increase the number of IGF-I binding sites in cells in culture. We show here that PDGF also increases the levels of IGF-1 receptor mRNA. Using cell lines stably transfected with an expression plasmid in which the reporter luciferase gene is under the control of the rat IGF-1 receptor gene promoter, we find that PDGF increases the activity of this promoter. A short IGF-1 receptor gene promoter, comprising about 100 base pairs of the sequence immediately upstream of the initiation of transcription site, is sufficient for a response to the stimulatory action of PDGF. These results suggest that an increase in RNA levels and in promoter activity may play an important role in the increase in IGF-1 receptor levels that occurs after stimulation by PDGF
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Scholarly Communication and Publishing Lunch and Learn Talk #11: The ULS Open Access Author Fee Fund
No full textAt the May 2014 talk, you will learn about the ULS Open Access Author Fee Fund--what it is, why we do it, how it works, and how the program is going so far
The R&D Tax Incentives
No full textThis article sets out some background information and reflections of the author on the R&D tax incentive schemes included in the Common Corporate Tax Base (CCTB) Proposal. In particular the author analyzes the stimulus to private R&D through ad hoc tax incentives included in the CCTB Proposal and dives into the actual provisions included in the Proposal highlighting the most relevant issues connected with their design and interpretation. Moreover, the author explores the interaction between the CCTB Proposal and the granting by Member States of domestic R&D tax incentives
Extinction of Human Insulin-Like Growth Factor II Expression in Somatic Cell Hybrids
No full textInsulin-like growth factor (IGF) II is a mitogenic polypeptide (1) that plays an important role in fetal and post-natal development (2). Both in human and rodents, IGF-II is a single copy gene that gives origin to a family of RNA transcripts (3-7). These heterogeneous mRNAs are originated from at least three promoters, functioning in many tissues of the rat during the embryonic and neonatal period (3,4,8). On the contrary, in adult animals, their expression is confined to the choroid plexus and to the leptomeninges (9). The human gene also utilizes three different promoters, two of them functioning in fetal liver and in most fetal tissues (5). The third one is a tissue specific promoter, active in adult liver only (6)
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