Search results for "Adrenergic"
showing 10 items of 433 documents
Peak half-width plots to study the effect of organic solvents on the peak performance of basic drugs in micellar liquid chromatography.
2009
The addition of the anionic surfactant sodium dodecyl sulphate (SDS) to hydro-organic mixtures of methanol, ethanol, propanol or acetonitrile with water yielded enhanced peak shape (i.e. increased efficiencies and symmetrical peaks) for a group of basic drugs (β-blockers) chromatographed with a Kromasil C18 column. The effect can be explained by the thin layer of surfactant associated to the hydrocarbon chain on the stationary phase in the presence of the organic solvents, which covers the free silanols on the siliceous support avoiding their interaction with the cationic basic drugs. These instead interact with the anionic head of the surfactant increasing their retention and allowing a mo…
Neuropeptide Y effects on pineal melatonin synthesis in the rat
1987
Neuropeptide Y (NPY)-like immunoreactivity is present in the rodent pineal gland. To elucidate possible effects on pineal melatonin synthesis NPY (5 nmol/kg body wt.) was injected into the common carotid artery of male rats. Activities of the melatonin biosynthetic enzymes, serotonin N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT) were determined by means of radioenzymatic methods. Intact light-exposed animal showed increased NAT activity at day- and at nighttime. Blinded animals showed a more than 10-fold reduction of NAT activity after nocturnal NPY injections. HIOMT activity was only slightly influenced at either time. These results are discussed in terms of the p…
Symptom variability and control in COPD: Advantages of dual bronchodilation therapy
2017
Abstract Background Chronic obstructive pulmonary disease (COPD) is a heterogeneous disorder characterized by usually progressive development of airflow obstruction that is not fully reversible. While most patients will experience symptoms throughout the day or in the morning upon awakening, many patients do not experience their symptoms as constant but report variability in symptoms during the course of the day or over time. Symptom variability adversely affects patients' health status and increases the risk of COPD exacerbations. Methods We examined data from the literature on symptom variability and control in patients with COPD, with focus on the use of inhaled bronchodilator therapy wi…
The Effect of Tyramine, Noradrenaline, and Angiotensin on the Blood Pressure in Hypertensive Patients with Aldosteronism and Low Plasma Renin
1970
The reactivity to the pressor action of tyramine, noradrenaline, and angiotensin was determined in 9 patients with hypertension, aldosteronism and low plasma renin concentration (4 patients with solitary adrenal adenomas, 3 patients with nodular adrenal hyperplasia, 2 patients with unknown adrenal status). In 7 patients tests were repeated following unilateral or subtotal adrenalectomy respectively. For comparison, 5 patients with phaeochromocytoma, 10 patients with benign essential hypertension, and 12 normotensive control subjects were studied. — In the hypertensive patients with aldosteronism and low plasma renin, responsiveness to tyramine was significantly reduced. In contrast, pressor…
Pharmacological Interventions on Asymmetric Dimethylarginine, a Clinical Marker of Vascular Disease
2011
The aim of this paper is to review the latest data on the pharmacological modulation of asymmetric dimethylarginine in human disease. When the terminal nitrogens of the guanidine portion of an arginine become methylated through the action of N-methyl transferases, two chemically close, but physiologically different amino acids are synthesized: symmetric and asymmetric dimethylarginine. The vascular origin of asymmetric dimethylarginine and its inhibitory activity on endothelial nitric oxide synthase give it an important role in certain diseases in which microcirculation is compromised: hypertension, atherosclerosis, inflammatory bowel disease, and diabetes. This review discusses the role th…
Cholinergic-Adrenergic Presynaptic Interactions on the Heart in the Millisecond Range as Studied With the Pulse-to-Pulse Method
1988
A method has been devised to study the interactions of cholinergic and adrenergic nerves in the rabbit atria, a tissue known to be densely innervated by both vagus and sympathetic nerve fibres. The atria were isolated and perfused via the ascending branches of the coronary arteries. The acetylcholine (ACh) stores were labelled with [14C]-choline and the noradrenaline (NA) stores with [3H]-NA. The radioactive compounds were separated on columns and determined by scintillation spectrometry.
Early management of COPD: Where are we now and where do we go from here? a delphi consensus project
2019
Fabiano Di Marco,1 Piero Balbo,2 Francesco de Blasio,3 Vittorio Cardaci,4 Nunzio Crimi,5 Giuseppe Girbino,6 Girolamo Pelaia,7 Pietro Pirina,8 Pietro Roversi,9 Pierachille Santus,10,11 Nicola Scichilone,12 Alessandro Vatrella,13 Patrizio Pasqualetti,14 Mauro Carone15 1Department of Health Sciences, University of Milan, Respiratory Unit, Papa Giovanni XXIII Hospital, Bergamo, Italy; 2SC Malattie dell’Apparato Respiratorio, AOU Maggiore della Carità, Novara, Italy; 3Respiratory Medicine and Pulmonary Rehabilitation Section, Clinic Center S.p.A. Private Hospital, Department of Medicine and Health Sciences “V Tiberio”, University of Molise, Campobasso, It…
Interpretive search of optimal isocratic and gradient separations in micellar liquid chromatography in extended organic solvent domains
2020
Abstract Micellar liquid chromatography (MLC) is a reversed-phase mode with mobile phases containing an organic solvent and a micellised surfactant. Most procedures developed in MLC are implemented in the isocratic mode, since the general elution problem in chromatography is less troublesome. However, gradient elution may be still useful in MLC to analyse mixtures of compounds within a wide range of polarities, in shorter times. MLC using gradients is attractive to determine by direct injection moderate to low polar compounds in physiological samples. In these analyses, the use of initial micellar conditions (isocratic or gradient) with a fixed amount of surfactant above the critical micell…
Micellar Liquid Chromatography: A Worthy Technique for the Determination of β-Antagonists in Urine Samples
1998
Several beta-antagonists (acebutolol, atenolol, celiprolol, labetalol, metoprolol, nadolol, propranolol) were determined in urine samples with fluorometric detection after direct injection, in less than 15 min, with a micellar mobile phase of 0.1 M sodium dodecyl sulfate (SDS), 15% propanol, and 1% triethylamine at pH 3. The limits of detection (38 criterion) were usually between 3 and 30 ng/mL. The addition of propanol and triethylamine and the reduction of the pH of the mobile phase improved the efficiency of the chromatographic peaks that was rather low in pure micellar eluents. The selection of the composition of the mobile phase was easily performed through the use of an interpretive p…
Performance of amines as silanol suppressors in reversed-phase liquid chromatography
2016
In reversed-phase liquid chromatography, cationic basic compounds yield broad and asymmetrical peaks, as a result of their ionic interaction with the anionic free silanol groups present in the silica-based stationary phases (commonly derivatised with C18 groups). A simple way to improve the peak shape is the addition to the hydro-organic mobile phase of a reagent (usually called additive) with cationic character. This associates with the stationary phase to prevent the access of analytes to the free silanol groups. Cationic additives may interact electrostatically with the anionic silanols. The hydrophobic region of the additive may also associate with the alkyl chains bound to the stationa…