1,721,005 research outputs found
Vasopressin Secretion Control: Central Neural Pathways, Neurotransmitters and Effects of Drugs.
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Diffuse Iodine-131 lung uptake in bronchiectasis: a potential pitfall in the follow up of differentiated thyroid carcinoma.
No full textBackground. I-131 total body scintigraphy is a commonly used post thyroidectomy imaging procedure in the management of differentiated thyroid cancer, in particular in patients with intermediate or high risk of persistent or recurrent disease, in combination with serum thyroglobulin determinations and ultrasound of the neck. It can show the persistence of residual thyroid tissue after thyroidectomy and local and distant metastases. Although this is a highly sensitive method for detecting normal and pathologic thyroid tissue, especially when performed after a radio-ablative dose, false-positive scans (i.e. uptake in the absence of residual thyroid tissue or metastases) can occur in different situations. Patient Findings. We report a case of a 42-yr-old woman with recurrent chest infections and bronchiectasis, who had a total thyroidectomy and I-131 treatment because of a papillary thyroid carcinoma. She presented with marked bilateral I-131 uptake in the lungs mimicking metastatic involvement of the lungs by thyroid cancer but interpreted as nonspecific bilateral uptake by her bronchiectatic bronchial tree. Summary. Our case, as well as others reported in the literature, calls attention to the fact that radioiodine lung uptake may be related to chronic inflammatory lung disease, thus representing a potential diagnostic pitfall in patients with differentiated thyroid cancer. Conclusions. I-131 uptake should be interpreted on the bases of clinical context, imaging and laboratory findings (serum Tg). Recognition of potential false-positive I-131 scans is critical to avoid unnecessary exposure to further radiation from repeated therapeutic doses of radioactive iodine with possible side effects and even worsening of lung disease itself
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
Role of central and peripheral chemoreceptors in vasopressin secretion control
No full textIn this review, we analyzed the role played by central and peripheral chemoreceptors (CHRs) in vasopressin (AVP) secretion control. Central neural pathways subserving osmotic and non-osmotic control of AVP secretion are strictly correlated to brain areas participating in chemoreception mechanisms. Among the different brain areas involved in central chemoreception, the most important site has been localized in the retrotrapezoid nucleus of the rostral ventrolateral medulla. These central CHRs are able to detect very small pH/CO2 fluctuations, participating in brain blood flow regulation, acid-base balance and blood pressure control. Decreases in arterial pH and increases in arterial pCO2 stimulate AVP release by the Supraoptic and Paraventricular Nuclei. Carotid CHRs transduce low arterial O2 tension into increased action potential activity, leading to bradycardia and coronary vasodilatation via vagal stimulation, and systemic vasoconstriction via catecholaminergic stimulation. Stimulation of carotid CHRs by hypoxia increases neurohypophyseal blood flow and AVP release, an effect inhibited by CHRs denervation. Two renal CHRs have been identified: Type R1 CHRs do not have a resting discharge but are activated by renal ischemia and hypotension; Type R2 CHRs have a resting discharge and respond to backflow of urine into the renal pelvis. Signals arising from renal CHRs modulate the activity of hypothalamic AVPergic neurons: activation of R1 and R2 CHRs, following increased intrapelvic pressure with solutions of mannitol, NaCl and KCl, produces a significant increase of AVP secretion and the same effect has been obtained by the intrarenal infusion of bradykinin, which excites afferent renal nerves, as well as by the electrical stimulation of these nerves
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