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Angiotensin II receptor antagonist CV-11974 and cerebral blood flow autoregulation
No full textOBJECTIVE: To investigate whether the angiotensin II (Ang II) subtype 1 receptor (AT1) antagonist CV-11974 had a similar effect to angiotensin converting enzyme inhibitors on cerebral blood flow autoregulation in normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR).METHODS: Sixteen WKY rats and 16 SHR were given CV-11974 0.1 mg/kg intravenously and compared with two control groups (n = 16). Their cerebral blood flow was measured with the intracarotid xenon-133 injection method and blood pressure was raised by noradrenaline infusion and lowered by controlled haemorrhage in separate groups of rats. The limits of autoregulation were determined by computed least-sum-of-squares analysis.RESULTS: The dose of CV-11974 given lowered blood pressure but did not influence baseline cerebral blood flow. In WKY rats the lower limit of autoregulation in control rats was 60 +/- 3 mmHg, whereas after CV-11974 administration it was 48 +/- 2 mmHg (P < 0.01). In SHR the corresponding values were 85 +/- 2 and 78 +/- 2 mmHg, respectively (P < 0.05). In WKY rats the upper limit of autoregulation in control rats was 144 +/- 5 mmHg, whereas after CV-11974 administration it was 126 +/- 7 mmHg (P < 0.05). In SHR the corresponding figures were 174 +/- 8 and 144 +/- 6 mmHg, respectively (P < 0.01).CONCLUSION: Thus, the AT1 receptor antagonist, although it did not influence baseline cerebral blood flow, shifted the autoregulation curve towards lower blood pressure. This effect is similar to that of angiotensin converting enzyme inhibitors, and might be due to release of Ang II-dependent tone in the larger cerebral resistance vessels.</p
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
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
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
ゲンチョ ノウソッチュウ エキハッショウ シゼン コウケツアツ ラット ニ オケル アンジオテンシン II 1ガタ ジュヨウタイ キッコウヤク CV 11974 ノ シンキン ホゴ コウカ ニツイテ
Get PDF【目的】アンジオテンシンIIの左室拡張能と左室の線維化,心肥大との関連を明らかにするために,脳卒中易発症自然高血圧ラット(SHRSP)を用い検討した。【方法】SHRSPに12週齢から24週齢まで,アンジオテンシンII 1型受容体拮抗薬 CV-11974を投与(0.5mg/kg i.p.)した治療群,ヒドララジンを投与(14-27mg/kg p.o.)した治療群および未治療群と正常血圧コントロールとしてのWKY群で収縮期血圧,心体重比,心筋細胞面積,間質の線維化,冠血管の中膜の厚さ,心筋 stiffness,反応充血時の最大冠灌流量,最小血管抵抗,ミオシン重鎖V3の割合を計測し比較検討した。【結果】CV-11974には心肥大抑制効果があるがヒドララジンでは認められなかった。しかし,降圧により間質の線維化は CV-11974とヒドララジンでは共に抑制が認められたが,冠血管周囲の線維化および中膜の肥厚の抑制効果は CV-11974にしか認められなかった。同様に,心筋 stiffness,冠予備能,さらにはミオシン重鎖の比率においても CV-11974にしか正常化させる効果がなかった。【結論】アンジオテンシンIIは心筋の phenotype changeや線維化を誘導する主要な因子であり,拡張能障害に深く関与していると考えられた
Beneficial Effects of CV- 11974 on Vascular Remodeling Induced by Long-term Volume Overload in Rabbits
Get PDF論文(Article)Long-term volume overload causes an enlargement of vessels. This study was undertaken to examine the effects of angiotensin II type 1 (AT-1) receptor antagonist CV-11974 on the flow-induced vascular remodeling. Our methods involued the use of an artcvia-venous shunt made between the left common carotid artery and the external jugular vein in 17 rabbits. Six weeks after the shunt formation, rabbits were randomly assigned to 2 groups: CV-11974 (CV) and saline groups. Two groups were administered CV or saline for 6 weeks. Sham-operated rabbits were given saline and used as control. The results showed a relationship between the cube of luminal diameter and flow was linear in CV and saline groups, and this relationship was steeper in CV than in saline group. In isolated carotid arteries, isometric tension produced by angiotensin II was significantly augmented at the shunt side in saline group, and this was attenuated to 8% and 7%, respectively, after CV in arteries of shunt and contralateral sites. Derangement of acetylcholine-induced endothelium dependent relaxation was noted at the shunt side as compared with the contralateral vessels, which was partially reverted to the level of sham by CV administration, our conclusions were that vascular remodeling, hypercontractile response to angiotensin II and reduced endothelium-dependent relaxation in chronic volume overload vessels were improved following a long-term administration of AT-1 antagonist. Key words : shunt, angiotensin, endothelium-derived factors, remodelin
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