Search results for "dilation"
showing 10 items of 304 documents
Generalized inverses and similarity to partial isometries
2010
Abstract We obtain some results related to the problems of Badea and Mbekhta (2005) [1] concerning the similarity to partial isometries using the generalized inverses. Especially, we involve the Moore–Penrose inverses. Also a characterization for such a similarity is given in the terms of dilations similar to unitary operators, which leads to a new criterion for the similarity to an isometry and to a quasinormal partial isometry.
Change of COPD maintenance medication over two years in a large real life cohort: The DACCORD study
2016
Introduction Database studies suggest a steady intensification of COPD maintenance medication, with the majority of patients eventually receiving a LABA/LAMA/ICS combination. However, such studies include generally only data on medication use. Here, we analysed data from the ongoing, non-interventional, observational DACCORD study to determine whether there was a correlation between baseline GOLD 2011 category and change in medication use over 2 years. Methods This abstract presents data on medication use at baseline and at 1 and 2 years, by baseline GOLD 2011 category (A,B,C and D with symptoms evaluated using the COPD Assessment Test). Results 3315 patients with COPD have completed the 2 …
Arachidonic acid relaxes human pulmonary arteries through K+ channels and nitric oxide pathways.
2004
We aimed to investigate the role of K(+) channels and nitric oxide (NO) on the relaxant effects of arachidonic acid in the human intralobar pulmonary arteries. Arachidonic acid produced a concentration-dependent relaxation (E(max)=93+/-3% of maximal relaxation induced by papaverine 0.1 mM;-log EC(30)=7.03+/-0.09) that was antagonized by the cyclooxygenase inhibitor indomethacin (1 microM), by the combination of cyclooxygenase blockade and cytochrome P450 (CYP) blockade with 17-octadecynoic acid (17-ODYA, 10 microM), by the combination of cyclooxygenase inhibition and NO synthase (NOS) inhibition with N(omega)-nitro-l-arginine (l-NOARG, 100 microM), by the simultaneous inhibition of CYP and …
Neurogenic contraction and relaxation of human penile deep dorsal vein
1998
The aim of the present study was to characterize neurogenic and pharmacological responses of human penile deep dorsal vein and to determine whether the responses are mediated by nitric oxide from neural or endothelial origin. Ring segments of human penile deep dorsal vein were obtained from 22 multiorgan donors during procurement of organs for transplantation. The rings were suspended in organ bath chambers for isometric recording of tension. We then studied the contractile and relaxant responses to electrical field stimulation and to vasoactive agents. Electrical field stimulation (0.5–2 Hz) and noradrenaline (3×10−10–3×10−5M) caused frequency- and concentration-dependent contractions that…
Topical capsaicin application and axon reflex vasodilatation of the tongue: A videocapillaroscopic study
2006
The aim of this study was to evaluate the effects of topical capsaicin application on human lingual mucosa and to assess if neurogenic inflammation might have a role in the pathogenesis of lingual diseases. Thirty patients (16 males and 14 females; mean age: 41.46 +/- 11.8 years; range: 23-60) were examined in our laboratory. The neurogenic inflammation was experimentally induced in the lingual mucosa close to 1) the left margin of the tongue and 2) the right margin of the tongue after ipsilateral nerve trunk anesthesia. The characteristics of lingual microcirculation were observed using computerized videocapillaroscopic techniques. The vasodilatation was observed close to the left margin o…
Relaxation by urocortin of human saphenous veins
2002
Urocortin, an endogenous peptide structurally related to corticotropin-releasing factor (CRF), has potent cardiovascular effects, suggesting that it may be of significance in cardiovascular regulation. The objective of this study was to analyse the effects of urocortin and its action mechanisms on human blood vessels. To this, 3 mm long segments from human saphenous veins were prepared for isometric tension recording in an organ bath. In the segments at basal resting tone, urocortin did not produce any effect, but in the segments precontracted with endothelin-1 (1 – 10 nM), urocortin (1 pM – 10 nM) produced concentration-dependent relaxation. This relaxation was not modified by the inhibito…
The Tolerability of Nilvadipine Compared to Nifedipine in Patients with Essential Hypertension
1992
In one multicenter, double-blind study, 659 hypertensive patients were treated for 16 weeks with either nilvadipine (n = 326) or nifedipine (n = 333). The major objective of the study was to compare the compatibility of the two calcium antagonists with regard to hepatic compatibility and side-effect profiles. The dosages were chosen so that the effective blood pressure reduction in both groups was equally good (mean decreases in systolic pressure of 27 +/- 12 mm Hg with nilvadipine and 26 +/- 15 mm Hg with nifedipine, and in diastolic pressure of 18 +/- 6 mm Hg with nilvadipine and 19 +/- 7 mm Hg with nifedipine). The mean heart rate was slightly lowered by about 2 beats/min by both substan…
Different β-adrenoceptor subtypes coupling to cAMP or NO/cGMP pathways: implications in the relaxant response of rat conductance and resistance vesse…
2013
Background and Purpose To analyse the relative contribution of β1-, β2- and β3-adrenoceptors (Adrb) to vasodilatation in conductance and resistance vessels, assessing the role of cAMP and/or NO/cGMP signalling pathways. Experimental Approach Rat mesenteric resistance artery (MRA) and aorta were used to analyse the Adrb expression by real-time-PCR and immunohistochemistry, and for the pharmacological characterization of Adrb-mediated activity by wire myography and tissue nucleotide accumulation. Key Results The mRNAs and protein for all Adrb were identified in endothelium and/or smooth muscle cells (SMCs) in both vessels. In MRA, Adrb1 signalled through cAMP, Adrb3 through both cAMP and cGMP…
Relaxant effects of antidepressants on human isolated mesenteric arteries
1999
Aims The therapeutic action of tricyclic agents may be accompanied by unwanted effects on the cardiovascular system. The evidence for the effects on vascular and nonvascular smooth muscle comes from animal studies. Whether these studies can be extrapolated to human vessels remains to be determined. Therefore, the present study was designed to investigate the influence of amitriptyline, nortriptyline and sertraline on the contractile responses of human isolated mesenteric arteries to electrical field stimulation, noradrenaline and potassium chloride. Methods Arterial segments (lumen diameter 0.8–1.2 mm) were obtained from portions of the human omentum during the course of 41 abdominal operat…
Pathological role of a constitutively active population of α1D -adrenoceptors in arteries of spontaneously hypertensive rats
2002
The role of a constitutively active population of α1D-adrenoceptors was analysed in arteries obtained from spontaneously hypertensive rats (SHR) and controls (WKY) divided into three groups: young prehypertensive, adult hypertensive, and adult animals chronically treated with captopril (50 mg kg−1 per day orally) in order to prevent the hypertensive state. In adult SHR, a significant increase in BMY 7378 potency (not in prazosin potency) was observed in aorta, mesenteric artery, and the first and second branches of the small mesenteric arteries with respect to WKY rats. This difference was not observed in iliac and tail arteries, which suggests an increased functional role of α1D-adrenocept…