Search results for "Oxide"
showing 10 items of 6424 documents
High affinity of "arbor" iron porphyrins for dioxygen
1998
International audience; The equilibrium rates of dioxygen and carbon monoxide binding have been measured for a series of capped iron porphyrins called "arbor". The affinity for dioxygen of these models is 100-fold higher than the highest previously reported values.
Nitric oxide metabolism is impaired by type 1 diabetes and diabetic nephropathy
2020
Diabetes leads to reduced nitric oxide bioavailability, resulting in endothelial dysfunction. However, overproduction of nitric oxide due to hyperglycaemia is associated with oxidative stress and tissue damage. The objective of this study was to characterise nitric oxide production (NO) and added nitrite and nitrate (NO(2)(-)+NO(3)(-)) concentration in the blood and urine of patients with and without diabetic nephropathy. A total of 268 patients with type 1 diabetes and 69 healthy subjects were included. Diabetic nephropathy was defined as macroalbuminuria and/or estimated glomerular filtration rate below 60 ml/min/1.73 cm(2). NO(2)(-)+NO(3)(-) concentration was measured by Griess reaction.…
A non-canonical chemical feedback self-limits nitric oxide-cyclic GMP signaling in health and disease
2018
Endothelial nitric oxide (NO) stimulates the heme protein, soluble guanylyl cyclase (sGC) to form vasoprotective cyclic GMP (cGMP). In different disease states such as pulmonary hypertension, NO-cGMP signaling is pharmacologically augmented, yet the pathomechanisms leading to its dysregulation are incompletely understood. Here we show in pulmonary artery endothelial cells that endogenous NO or NO donor compounds acutely stimulate sGC activity, but chronically down-regulate both sGC protein and cGMP formation. Surprisingly, this endogenous feedback mechanism was independent of canonical cGMP signaling via cGMP-dependent protein kinase. It did not involve thiol-dependent modulation, a process…
Nitric oxide metabolites (nitrite and nitrate) in several clinical condition.
2013
We determined the concentration of nitric oxide metabolites (NO2-+NO3-), expressed as NOx, in several clinical conditions. Regarding this, we have examined 25 subjects with arterial hypertension, 41 subjects with chronic kidney disease in conservative treatment, 106 subjects with metabolic syndrome subdivided according to the presence (n = 43) or not (n = 63) of diabetes mellitus, 48 subjects with obstructive sleep apnea syndrome (OSAS), 14 women with systemic sclerosis complicated with Raynaud's phenomenon, 42 dialyzed subjects and 105 young subjects with acute myocardial infarction (AMI). In subjects with arterial hypertension, chronic kidney disease, metabolic syndrome, systemic sclerosi…
NG-monomethyl-L-arginine and NG-nitro-L-arginine inhibit endothelium-dependent relaxations in human isolated omental arteries.
1991
Abstract The L-arginine analogues NG-monomethyl-l-arginine (l-NMMA, 10−4 m) and NG-nitro-L-arginine methyl ester (l-NAME, 10−4 m), which specifically inhibit the synthesis of nitric oxide from l-arginine, significantly reduced acetylcholine-induced endothelium-dependent relaxations in rings of human omental arteries. The inhibitory potency of l-NMMA and l-NAME was similar. Addition of l-NMMA or l-NAME to the organ bath did not induce any significant changes in the resting tension of the tissues. The effects of l-NMMA were reversed by l-arginine (3 × 10−4 m). The l-NMMA enantiomer, d-NMMA (10−4 m), did not influence either the basal tone of the preparation or the relaxing effects of acet…
Electrochemical characterization of cobalt cordierites attached to paraffin-impregnated graphite electrodes
2004
The electrochemistry of α, β and μ cobalt-containing cordierites (Co2Al4Si5O18) attached to paraffin-impregnated graphite electrodes has been studied by linear scan and cyclic voltammetries in HCl+NaCl and NaOH electrolytes. This electrochemistry is compared with that of vitreous cobalt cordierite, cobalt(II) oxide and cobalt spinel aluminate (CoAl2O4), the two last taken as reference materials. Electrochemical processes involve the site-characteristic reduction of Co(II) species to cobalt metal near to −0.5 V vs. SCE and their oxidative dissolution near +0.3 V, accompanied by solid state interconversion between Co(II) and Co(III) at potentials above +0.45 V. Cordierite-modified electrodes …
Structural Changes of Titanium Oxide Induced by Chromium Addition as Determined by an X-Ray Diffraction Study
1995
Abstract An X-ray diffraction study has been carried out on a series of polycrystalline TiO 2 (anatase) catalysts containing Cr(III) at different atomic concentrations (0.2-5.0 at. %), prepared by a co-precipitation method. Analysis of the variation of the unit cell parameters of chromium-doped anatase with respect to pure anatase has allowed us to estimate the solubility limit for the system at around 1.4 at. %. There is no evidence for the existence of a separate crystalline chromium oxide phase. Temperature effects on the cell parameter and on the anatase-rutile transformation rate were also analyzed. An increase in temperature produced release of the chromium from the solid solution. At…
The different catalytic behaviour in the propane total oxidation of cobalt and manganese oxides prepared by a wet combustion procedure
2013
Abstract Cobalt oxide and manganese oxide catalysts have been prepared through aqueous synthesis using a wet combustion procedure. These materials have been tested as catalysts for the total oxidation of propane. It has been observed a different catalytic behaviour between cobalt and manganese oxides although for both oxides a very high catalytic activity has been obtained. Cobalt oxides prepared by the wet combustion procedure are less reactive than a simple cobalt oxide prepared without the addition of organic acids. However, in the case of manganese oxide the use of organic acids highly increases the catalytic activity. The different catalytic behaviour has been related to the variation …
A step forward in the development of superoxide dismutase mimetic nanozymes: the effect of the charge of the surface on antioxidant activity
2019
Two binucleating hezaaza macrocycles containing a pyridinol spacer have been prepared and characterised. Protonation studies indicate the deprotonation of the phenol group at relatively low pH values with the concomitant occurrence of a keto-enolic equilibrium. These ligands readily form binuclear Cu2+ and Zn2+ complexes as denoted by potentiometric and spectroscopic studies. The binding of the metals yields to the ready deprotonation of the phenol with the stabilisation of the keto form that results in complexes of greater stabilities than the analogous ones containing pyridine as spacer instead of pyridine. Mixed Cu2+–Zn2+-complexes were also detected in aqueous solutions containing equim…
First Synthesis of β-Keto Sulfoxides by a Palladium-Catalyzed Carbonylative Suzuki Reaction
2005
[reaction: see text] An unprecedented palladium-catalyzed three-component cross-coupling reaction between alpha-bromo sulfoxide, carbon monoxide, and aromatic boronic acids provides a new and efficient approach to the synthesis of beta-ketosulfoxides. The reaction takes place under mild conditions with a wide range of variously substituted aryl and heteroaryl boronic acids. The carbonylative cross-coupling reaction is strongly favored over competing direct cross-coupling and homocoupling processes, except with boronic acids carrying strong electron-withdrawing substituents.