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MEASUREMENT OF CARDIAC-OUTPUT BY M-MODE AND 2-DIMENSIONAL ECHOCARDIOGRAPHY - APPLICATION TO PATIENTS WITH HYPERTENSION
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Echocardiographic measurement of left ventricular mass and volume in normotensive and hypertensive rats: necropsy validation
No full textEchocardiographic measurement of left ventricular mass and volume in normotensive and hypertensive rats. Necropsy validation.
No full textAlthough rats are commonly used to study left ventricular (LV) hypertrophy, measurement of LV mass and dimensions has required killing the rat. To determine the accuracy of echocardiography in rats, blinded crossectional area (CSA) and LV mass measurements using either the cube function (LVM) or an elliptical model (LVMel) from high resolution M-mode echocardiograms were compared to necropsy LV weight (0.28 to 1.5 g), in 41 normotensive (body weight 116 to 762 g) and 17 hypertensive rats (350 to 560 g). Postmortem chamber volumes in 28 normal rats (0.02 to 0.19 mL) were also compared to echocardiographic volumes derived from the elliptical model. Correlation with LV weight was r = 0.87 for LVM, 0.90 for CSA and 0.93 for LVMel (all P less than .00001). Comparison of hypertensive and body-weight-matched normotensive rats revealed the upper normal limit for both LVMel and CSA to have 89% sensitivity and 100% specificity for detection of post mortem LV hypertrophy. Necropsy LV volumes were more closely related to systolic echocardiographic volumes than to diastolic volumes (r = 0.78 v 0.71, both P less than .00001), compatible with the effects of post mortem contracture. Stroke volume determined invasively in 5 Wistar rats by thermodilution was similar to that obtained using elliptical model echo volumes in 5 rats of the same body size (0.35 +/- 0.05 v 0.30 +/- 0.06 mL/beat). Echocardiography can be used to evaluate LV structure and function in rats and to detect in vivo LV anatomic differences induced by hypertension
Influence of sodium intake on in vivo left ventricular anatomy in experimental renovascular hypertension.
No full textThe effect of different dietary salt contents (0.0035, 0.4, and 4%) on in vivo left ventricular (LV) geometry was studied by necropsy-validated echocardiographic methods in groups of 30 two-kidney, one-clip (2K, 1C) and one-kidney, one-clip (1K, 1C) male Wistar rats and two-kidney (2K) and one-kidney (1K) shams 9 wk after surgery. The salt-deficient diet was associated with lower body weight, higher plasma renin activity in both 2K,1C and 2K shams (P < 0.004) and higher hematocrit in 2K,1C (P < 0.02). Blood pressure was increased by high-salt diet in experimental groups but not in shams (P < 0.01). Increase in dietary sodium content was associated with increased cross-sectional area index (CSAI) and LV mass index in 2K rats independently of renal artery stenosis (P < 0.0007) and also in 1K shams (P < 0.01). LV end-diastolic dimension was greater in 1K,1C and 1K shams than in 2K,1C and 2K shams at every level of sodium intake and was directly related to atrial natriuretic factor levels in both 1K,1C (r = 0.68) and 2K,1C (r = 0.59). LV hypertrophy was independently predicted by blood pressure (P < 0.0006) and high-sodium diet (P < 0.05) in 1K rats (multiple r = 0.57, P < 0.001) and by high-sodium diet (P < 0.0001) and low hematocrit (P < 0.05) in 2K rats (multiple r = 0.76, P < 0.0001). Thus provision of normal or high sodium content in the diet was a more consistent stimulus to LV hypertrophy than the level of blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS
Relation of left ventricular hypertrophy, afterload, and contractility to left ventricular performance in Goldblatt hypertension.
No full textRelation of left ventricular hypertrophy, afterload, and contractility to left ventricular performance in Goldblatt hypertension.
No full textTo analyze the determinants of left ventricular (LV) performance (myocardial afterload, chamber size, mass, and contractility) in Goldblatt hypertension, 19 anesthetized one-kidney, one-clip (1K1C) and 28 two-kidney, one-clip (2K1C) male Wistar rats were studied 58 to 62 days after clipping, together with 19 sham-operated and 13 normal rats (controls), by M-mode echocardiography using necropsy-validated methods of measurement. The LV fractional shortening was inversely related to end-systolic stress in all groups (r = -0.89 to -0.95, all P less than .00001): 7 2K1C (25%) and 9 1K1C (47%) had fractional shortening above the upper confidence limit in control animals. Both 1K1C and 2K1C with high LV performance had severe hypertension, inadequate LV hypertrophy, with resultant high wall stress (both P less than .005), increased LV chamber dimension (P less than .005 and P less than .05, respectively) and high afterload-corrected fractional shortening (both P less than .001); 2K1C also had high plasma renin activity and atrial natriuretic factor levels (both P less than .01). Rats with normal LV performance exhibited mild hypertension, adequate LV hypertrophy (normalizing wall stress), and normal LV chamber size and afterload-corrected fractional shortening. Thus, 8 1/2 weeks after clipping, adequate LV hypertrophy allows maintenance of normal LV function by normalizing myocardial afterload in a majority of rats with Goldblatt hypertension, whereas increased LV contractility (and possibly use of preload reserve in 1K1C) maintains normal LV function in the presence of inadequate LV hypertrophy and elevated wall stress, in a substantial minority of rats that developed more severe Goldblatt hypertension
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
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