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Postischemic hyperemia in subjects with lower limbs obstructive arteriopathy: Role of PGI-2 and endothelin
No full textThe physiological basis of postischemic hyperemia is not yet fully understood. The present study investigated the effects of pharmacologic manipulation of the prostaglandin system on local hemodynamics. Strain-gauge plethysmography was used to study 8 normal subjects and 9 patients with obliterating arterial disease of the lower limbs. Hemodynamic evaluations were performed before treatment, after seven days of low-dose acetylsalicylic acid (100 mg/day) to inhibit platelet thromboxane synthesis, and after acute infusion of 1 g of acetylsalicylic acid to inhibit endothelial prostacyclin synthesis. In patients with arterial disease, the hemodynamic study was also carried out after infusion of iloprost, a synthetic prostacyclin analogue. Acute infusion of acetylsalicylic acid significantly reduced basal blood flow in normal subjects, but not in patients with arterial disease. In the latter group, iloprost affected neither basal nor maximal postischemic flow. The study also evaluated the role of endothelin in musculocutaneous hemodynamic regulation, both in physiological conditions and in atherosclerosis. This part of the study addressed the possibility that the hemodynamic effects of vasodilator prostanoids like prostacyclin might affect endothelin release in vivo. During reactive hyperemia, plasma endothelin was reduced in normal subjects (-1.02 pg/mL, 95% CI: -2.23, 0.08), but not in patients with atherosclerosis (-0.35 pg/mL, 95% CI: -1-45, 0.75). In both groups, plasma endothelin was not affected by aspirin. These findings confirm the role of prostacyclin in local hemodynamic regulation. in the normal subject, musculocutaneous blood flow seems to depend at least in part on the action of vasodilator prostanoids and endothelin. This is not the case in patients with arterial disease, in whom plasma endothelin does not seem to be affected by postischemic changes in blood flow. A possible explanation for this difference could be alteration of the endothelial function in patients with arterial disease, related to the functional and structural characteristics of the artery wall in atherosclerosis
Changes in peripheral hemodynamics and vasodilating prostaglandins after high-dose short-term ibuprofen in chronically treated hypertensive patients
No full textThe use of cyclooxygenase inhibitors has been seen to reduce the efficacy of many antihypertensive drugs. However, cyclooxygenase inhibitors are normally non-selective because they affect both vascular tissue, where the endothelial Prostanoids exert principally a vasodilatory action, and the kidneys, where they also play an important role in regulating hydroelectrolytic metabolism by redistribution of intraparenchymal flow. To evaluate the relative importance of vascular district in the hypertensive patient, we administered ibuprofen - a drug acting with only a minimal antagonist activity. A group of 20 male hypertensives were randomly allocated, according to a single-blind protocol, to treatment with amlodipine (A, 10 mg/day) or lisinopril (L, 20 mg/day). Blood pressure was significantly reduced after 30 days, with a mean difference of -21.75 mmHg for systolic blood pressure (SBP) (95% confidence interval (CI): -27.46 to -16.04; P lt 0.0001) and -14.15 mmHg for diastolic blood pressure (DBP) (95% CI: -17.13 to -11.17; P lt 0.0001). Brachial artery compliance showed a mean increase of 1.657 times 10-7 dyn-1 cm-4 (95% CI: 1.188 to 2.126; P lt 0.001), and forearm resistances showed a mean decrease of -41.973 mmHg ml-1 s (95% Cl: -75.479 to -8.467; P = 0.017). Changes in compliance were significantly related to those in SBP (r = -0.546; P = 0.013). The administration of ibuprofen (400 mg, three times a day for 3 days) was accompanied by a slight but significant increase in SBP, but not in brachial artery compliance or forearm resistances. Only SBP was affected, showing a mean increase of 4.25 mmHg (95% CI: 1.26 to 7.24; P = 0.008). There was also reduced urinary excretion of PGI-2 and TXA-2 metabolites. The mean change in 6-keto-PGF-1alpha and 2,3-dinor-6-keto-PGF-1alpha was -45.71 ng per g urinary creatinine (uCr) (95% CI: -0.16 to -91.25; P = 0.049) and -73.17 ng (g uCr)-1 (95% CI: -38.81 to -107.53; P lt 0.001), respectively. The mean decrease in TXA-2 catabolites was highly significant: -39.2 ng (g uCr)-1 (95% CI: -18.17 to -60-22; P lt 0.001) and -102.87 ng (g uCr)-1 (95% CI: -61.86 to -143.88; P lt 0.001) for TXB-2 and 2,3-dinor-TXB-2, respectively. Our study highlighted an inverse correlation between changes in blood pressure and those in urinary 2,3-dinor-6-keto-PGF-1alpha, excretion, irrespective of antihypertensive regimen. This suggests that, in the hypertensive patient treated with NSAIDs, inhibition of vascular prostanoid synthesis may play an important role in countering the efficacy of an important vascular tone regulatory mechanism
Prostaglandin I2 and thromboxane B2 biosynthesis and haemodynamic effects of lisinopril.
No full textAntihypertensive activity of lisinopril is associated with changes in prostanoid generatio
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
Amlodipine and haemodynamic effects of cyclo-oxygenase inhibition
No full text1. The haemodynamic effects of calcium antagonists could depend at least in part on the activity of vasoactive prostanoids. 2. We set out to study the effect of the cyclo-oxygenase inhibitor ibuprofen, 400 mg three times daily for 3 days, by a randomised cross-over study vs placebo in 12 mild to moderate essential hypertensive patients who had been treated for 1 month with amlodipine. 3. Blood pressure, heart rate and vascular resistances in the upper limb (Doppler ultrasound) were measured. Plasma renin activity and urinary aldosterone, as well as indices of renal function, were evaluated. Urinary 2,3-dinor-6-keto-PGF1 alpha and 2,3-dinor-TXB2, as well as 6-keto-PGF1 alpha and TXB2, were measured as indices of systemic and renal PGI2 and TXA2 synthesis. 4. Amlodipine normalised blood pressure and reduced upper limb vascular resistances; it did not affect urinary prostanoid excretion. Short-term combined administration of ibuprofen resulted in, by comparison with placebo, inhibition of systemic PGI2 (-80.5 ng 24 h-1, 95% CI -99.2, -61.4; P < 0.001) and TXA2 (-216.1 ng 24 h-1, 95% CI -276.5, -155.8; P < 0.001), together with an increase in systolic (+7.8 mm Hg, 95% CI +3.1, +12.3; P < 0.01) and diastolic (+3.9 mm Hg, 95% CI +1.2, +6.6; P < 0.01) blood pressure; it had no significant effect on regional vascular resistances (+4.7 mm Hg ml-1 s, 95% CI -5.6, +15.0). Effects of ibuprofen on renal prostanoid synthesis were less marked, and there was no change in indices of renal function or hydro-electrolytic balance.(ABSTRACT TRUNCATED AT 250 WORDS
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
Prevalence of morphological alterations in cervical vessels: A colour duplex ultrasonographic study in a series of 3300 subjects
No full textBackground. In order to define the morphological variants involved in carotid elongation in terms of their clinical implications, we have analysed the prevalence of morphological alterations in patients routinely subjected to carotid colour duplex ultrasonography evaluation. Methods. From January 1, 1993 to June 30, 1996 3300 subjects were examined for central nervous system symptoms (41% of cases) or for screening related to ischaemic heart disease, lower limb arterial disease, hypertension or major dyslipidaemia (59% of cases). The chisup 2-test was used for statistical analysis. Results. Morphological alterations increased with age. While kinking was more prevalent in females (female:male ratio 58% vs 42%), sharp kinking was significantly more frequent in males (39% vs 15%, p < 0.001). Atheromatous plaques predominated in males (79% vs 46%, p < 0.001), as well as cases with haemodynamically significant involvement (16% vs 7%, p < 0.001). In patients with kinking there was a prevalence of haemodynamically significant lesions (chisup 2 = 52.7, p < 0.001). A possible link between conformational abnormalities and hypertension appeared highly significant owing to a very different prevalence of high blood pressure in the group of subjects with kinking (chisup 2 = 239, p < 0.001). We did not find a significant association between major neurological symptoms and the presence of kinking (chisup 2 = 0.215, p = 0.643), but we found an association with transient ischaemic attacks (chisup 2 = 6.9, p < 0.01). Conclusions. Conformational abnormalities like kinking, seem much more prevalent in subjects suffering from arterial hypertension. Even though high blood pressure is an important risk factor for transient ischaemic attacks, it is possible that the prevalence of atheromatous lesions and the flow turbulence linked to kinking may also play a role in their pathophysiology
Lisinopril and amlodipine in forearm hemodynamics in the hypertensive patient. Changes induced by ibuprofen.
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