1,721,139 research outputs found
Effects of Antihypertensive Drugs on Central Blood Pressure in Humans: A Preliminary Observation
No full textBACKGROUND: Central blood pressure (BP) is considered a better predictor of cardiovascular events than brachial BP. Modifications of central, beyond brachial BP, can be assessed by pressure amplification, a potential new cardiovascular risk factor. Comparison between drugs' effect on central hemodynamics has been poorly studied. Our aim was to assess the hemodynamic effect of a 12-week treatment with amlodipine 5mg, or candesartan 8mg, or indapamide sustained-release 1.5mg, in comparison with placebo.
METHODS: We analyzed 145 out-patients with essential hypertension in primary prevention enrolled in the Natrilix SR Versus Candesartan and Amlodipine in the Reduction of Systolic Blood Pressure in Hypertensive Patients (X-CELLENT) study, a multicenter, randomized, double-blinded, placebo-controlled trial. Arterial stiffness, central BP, pressure amplification, and wave reflection were measured by applanation tonometry.
RESULTS: Baseline characteristics of patients were homogeneous between groups. After treatment, we found that active drugs produced similar reduction of both central and peripheral BPs, with no significant interdrug differences (all P < 0.05; excluded peripheral pulse pressure, compared with placebo). Second, amlodipine (1.9% ± 15.3%), candesartan (3.0% ± 14.6%) and indapamide (4.1% ± 14.4%) all increased pulse pressure amplification, but only indapamide was statistically different from placebo (P = 0.02). Finally, no significant changes were observed on pulse wave velocity, heart rate, and augmentation index.
CONCLUSIONS: The 3 antihypertensive drugs similarly reduced peripheral and central BP, as compared with placebo, but a significant increase in pulse pressure amplification was obtained only with indapamide, independently of arterial stiffness modifications
Visit-to-visit variability: Prognostic significance?
No full textHypertension is the most prevalent treatable risk factor for stroke. Treatment of hypertension is based on usual blood pressure, which is evaluated by repeated measurement. When only few measurements show high blood pressure, this is considered as a background noise generally due to white coat effect. Rothwell et al. challenged this notion and presented data from post-hoc analyses of three randomized trials and one meta-analysis, where 3 parameters are strongly associated with the risk of stroke: visit-to-visit variability of systolic blood pressure, increased residual variability in treated patients, and episodic hypertension. These findings are not proof of a causal link between variability and vascular risk. However, a new window has been opened in clinical practice, giving new implications in the choice of treatment, and, for next trials, highlighting the importance of including variability and patients with episodic hypertension. © 2012 Elsevier Masson SAS
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
Comparison of central blood pressure devices on the basis of a modified protocol of the European Society of Hypertension: Application to the Centron cBP301
No full textOBJECTIVES: Central blood pressure (cBP) and pulse pressure amplification (PPA) are receiving renewed interest with the increase in the availability of noninvasive techniques that enable its measurement. However, to date, there is no standardized protocol to validate their accuracy. Although invasive comparison seems intellectually ideal, it will soon raise technical and ethical issues with the growing number of devices to be validated. We proposed a modified ESH-IP2010 protocol for electronic brachial devices to validate noninvasively systolic cBP and pulse pressure amplification, and used it to compare the newly commercialized Centron cBP301 device with radial tonometry SphygmoCor. METHODS: Radial tonometric SphygmoCor measurements were performed four times alternated with three Centron cBP301 measurements. Each Centron recording was compared with the most favourable SphygmoCor recordings performed immediately before or after and calibrated with Centron peripheral systolic and diastolic blood pressure measurements. RESULTS: Following protocol requirements, 33 individuals (21 men and 12 women) were recruited in the low, medium and high peripheral BP range. Systolic cBP varied from 88 to 188 and the difference between the devices was-0.33±3.28 mmHg (m±SD). It fell within the ESH-IP2010 pass requirements for the number of measurements within 5, 10 and 15 mmHg. The PPA varied from 1.13 to 2.09 and the difference between devices was -0.03±0.11, which showed good agreement for the PPA. CONCLUSION: The Centron cBP301 device was compared with the similarly calibrated SphygmoCor with a modified ESH-IP2010 protocol. It provided accurate measurements of systolic cBP and PPratio. © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Effect of Antihypertensive Agents on Blood Pressure Variability
No full text
To investigate the effect of different antihypertensive agents on blood pressure (BP) variability (BPV) and the underlying mechanism, we analyzed the ambulatory BP monitoring data of 577 patients before and after 3-month antihypertensive treatment, in the Natrilix SR Versus Candesartan and Amlodipine in the Reduction of Systolic Blood Pressure in Hypertensive Patients (X-CELLENT) Study, a multicenter, multinational, randomized, double-blind, placebo-controlled study with 4 parallel treatment arms (placebo, candesartan, indapamide sustained release, and amlodipine). Within-subject mean and SD of 24-hour BP, weighted by time interval between consecutive readings, were calculated in 3 time frames (daytime, nighttime, and 24 hours) to evaluate BP and BPV. The mean 24-hour heart rate (HR) and HR variability were calculated with the same algorithms. We found that the 3 antihypertensive drugs had a similar BP-lowering effect (
P
<0.001 for all), but amlodipine (
P
<0.007) and indapamide sustained release (
P
<0.04) were the only agents associated with a significantly decreased BPV after 3-month treatment. On the other hand, the major determinants of BPV at baseline were age, mean BP, and the corresponding HR variability. However, the reduction in BPV by amlodipine was significantly associated with the reduction in BP (
P
<0.006) and the reduction in HR variability (
P
<0.02), whereas the corresponding reduction by indapamide sustained release was only associated with the reduction in HR variability at night (
P
=0.004). In summary, 3-month amlodipine or indapamide sustained release treatment was associated with a significant reduction in BPV, and the mechanism of those reductions was possibly attributable to lowering BP or ameliorating the autonomic nervous system regulation or both. The combination of the 2 agents might help to optimize such properties.
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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
Blood pressure variability in relation to autonomic nervous system dysregulation: the X-CELLENT study
No full textThe purpose of this study was to investigate the association of autonomic nervous system dysregulation with blood pressure variability. Among the 2370 participants in the X-CELLENT study, 577 patients (59.0±10.2 years) were randomly selected to participate in an ancillary ambulatory blood-pressure monitoring study. We proposed a novel autonomic nervous system regulation index termed dSBP/dHR, which was defined as the steepness of the slope of the relationship between the 24-h systolic blood pressure (SBP) and the heart rate (HR) for each participant. Within-subjects s.d. of SBP, weighted for the time interval between consecutive validated readings from 24-h ambulatory blood pressure monitoring, was used to evaluate blood pressure variability. When dSBP/dHR was divided into tertiles, we observed a progressive increase from tertile 1 to tertile 3 in the daytime SBP, a progressive decrease in nighttime SBP, and consequently a progressive increase in the day-night SBP gradient (P<0.001). The s.d. of both daytime and nighttime SBPs were consistently and significantly increased from tertile 1 to tertile 3 (P<0.01). Both before and after adjustment for age, gender and 24-h mean blood pressure, all of these increasing and decreasing trends reached statistical significance (P<0.01). Furthermore, in our sensitivity analysis, when men and women were considered separately, the findings remained unaltered. In summary, autonomic nervous system dysfunction was associated with a heightened day-night SBP gradient and more variable SBP over 24 h in patients with essential hypertension. © 2012 The Japanese Society of Hypertension All rights reserved
Non-Invasive Estimation of Central Systolic Blood Pressure by Radial Tonometry: A Simplified Approach
Full text linkBackround. Central systolic blood pressure (cSBP) provides valuable clinical and physiological information. A recent invasive study showed that cSBP can be reliably estimated from mean (MBP) and diastolic (DBP) blood pressure. In this non-invasive study, we compared cSBP calculated using a Direct Central Blood Pressure estimation (DCBP = MBP2/DBP) with cSBP estimated by radial tonometry. Methods. Consecutive patients referred for cardiovascular assessment and prevention were prospectively included. Using applanation tonometry with SphygmoCor device, cSBP was estimated using an inbuilt generalized transfer function derived from radial pressure waveform, which was calibrated to oscillometric brachial SBP and DBP. The time-averaged MBP was calculated from the radial pulse waveform. The minimum acceptable error (DCBP-cSBP) was set at <= 5 (mean) and <= 8 mmHg (SD). Results. We included 160 patients (58 years, 54%men). The cSBP was 123.1 +/- 18.3 mmHg (range 86-181 mmHg). The (DCBP-cSBP) error was 1.4 +/- 4.9 mmHg. There was a linear relationship between cSBP and DCBP (R-2 = 0.93). Forty-seven patients (29%) had cSBP values >= 130 mmHg, and a DCBP value > 126 mmHg exhibited a sensitivity of 91.5% and specificity of 94.7% in discriminating this threshold (Youden index = 0.86; AUC = 0.965). Conclusions. Using the DCBP formula, radial tonometry allows for the robust estimation of cSBP without the need for a generalized transfer function. This finding may have implications for risk stratification
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