1,720,958 research outputs found
Thyroid Phylogeny: from seaweeds to man
No full textIodine uptake and production of iodine-aminoacids are evolutionarily very old phenomena. Seaweed are the first eukaryotic organism presenting these functions; they are rich in iodine and are at basis of the food chain. The monoiodotirosines, precursors of thyroxine, have been identified in a wide variety of invertebrates, such as Gorgonians and Tunicates. The structure of the thyroid appears for the first time in Cyclostomes adults (Lamprey), while in Tunicates (Ciona intestinalis) and Amphioxus is present a similar structure, the endostyle, which is an invagination of the ventral wall of the pharynx containing glandular cells that are able to concentrate iodine. This is not a true endocrine gland because the secretion is poured into the alimentary canal. In the larva of Lamprey (Ammocoetes) during the metamorphosis some of the epithelial cells persist and transform in the follicles. The cyclostomes, therefore, represent a link between the endostyle of protochordates and the thyroid gland of higher chordates. This hypothesis is confirmed by molecular genetic studies which have demonstrated the expression of Thyroid Transcription Factor (TTF-1) in the endostyle of Ciona, Lamprey and Amphioxus. The TTF-1 is an ancestral transcription factor which controls the survival of thyroid follicular cells at the beginning of organogenesis and regulates the expression of thyroid-specific genes in adult life. Clin Ter 2012; 163(2):e73-7
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
Interpretation of serum calcitonin in patients with chronic autoimmune thyroiditis
No full textCalcitonin (CT) is an important clinical marker for the diagnosis and follow-up of medullary thyroid carcinoma, although it is not absolutely specific. Some authors have reported C-cell hyperplasia in a number of thyroid specimens affected by Hashimoto's thyroiditis. The association between thyroiditis and hypercalcitoninemia is still controversial because some authors have reported low CT levels. The aim of this study is to evaluate the basal CT values in patients with and without thyroid autoimmunity. From May 2005 to February 2010, 1073 patients underwent ultrasonography-guided fine-needle aspiration cytology at the Thyroid Center of Sapienza University of Rome, with evaluation of basal serum FT4, FT3, TSH, and antithyroid peroxidase (anti-TPO) antibodies as well as CT levels. Forty-one patients presented a basal CT level above the reference upper limit. The mean serum CT was significantly lower in women than in men (4.28 +/- 6.63 vs 7.50 +/- 25.50 pg/ml; P0.05). Importantly, the rate of 'suspicious' CT values (above the 10 pg/ml cutoff) was not significantly different between patients with or without thyroid autoimmunity (3.9 vs 3.0%). Patients with hypercalcitoninemia suffering from chronic autoimmune thyroiditis should undergo the same clinical evaluation procedure as patients do without thyroid autoimmunity. Endocrine-Related Cancer (2012) 19 345-34
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
Thyroid function in 195 infertile patients undergoing assisted reproduction.
No full textThere is a known association between hypothyroidism and decreased fertility, which is mainly associated with ovulatory disturbances. According to literature data, women who require treatment with levothyroxine have a twofold increased risk of primary ovulatory infertility and in infertile women the prevalence of those positive for thyroid peroxidase antibodies is higher than in control group. Nowadays, infertile couples undergo assisted reproduction technologies (ART), including in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). The pregnancy rate of women undergoing ART appears to be significantly lower in subjects who are positive for organ-specific autoantibodies such as antithyroid and antiovarian antibodies. We retrospectively evaluated 195 procedures of assisted reproduction technologies performed at Fertility Center of Sapienza University of Rome, for which thyroid function data were recorded (including serum TSH and free thyroxine). The mean age of women treated was 37.39 (range 24-48). We considered as endpoints the number of oocytes retrieved, the number and grade of embryos transferred after fertilization , and the number of clinical pregnancies. In 77 procedures, the presence of thyroid peroxidase antibodies was evaluated, and thyroid autoimmunity was present in 9 cases. No significant differences were recorded in the number of oocytes retrieved and in the number of embryos transferred between the two groups. No pregnancy occurred in women with thyroid autoimmunity. 34 procedures were performed during treatment with levothyroxine. No significant differences were recorded in the number of oocytes retrieved, in the number of embryos transferred between the two groups and in the pregnancy rate. These data suggests that, in women undergoing ART, the ovarian response to stimulation and the pregnancy rate seems to be not influenced by either the presence of thyroid peroxidase antibodies or treatment with levothyroxine. Further studies are – however – in progress
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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