Encontrados 14 documentos, a visualizar página 1 de 2
Biomimetic sensor based on hemin/carbon nanotubes/chitosan modified microelectr...
Santos, Ricardo M.; Rodrigues, Marcelo S.; Laranjinha, João; Barbosa, Rui M.A novel biomimetic microsensor for measuring nitric oxide (NO) in the brain in vivo was developed. The sensor consists of hemin and functionalized multi-wall carbon nanotubes covalently attached to chitosan via the carbodiimide crosslinker EDC followed by chitosan electrodeposition on the surface of carbon fiber microelectrodes. Cyclic voltammetry supported direct electron transfer from the FeIII/FeII couple of...
The potent vasodilator ethyl nitrite is formed upon reaction of nitrite and eth...
Gago, Bruno; Nyström, Thomas; Cavaleiro, Carlos; Rocha, Bárbara S.; Barbosa, Rui M.; Laranjinha, João; Lundberg, Jon O.By acting as a bioreactor, affording chemical and mechanical conditions for the reaction between dietary components, the stomach may be a source of new bioactive molecules. Using gas chromatography-mass spectrometry we here demonstrate that, under acidic gastric conditions, ethyl nitrite is formed in µM concentrations from the reaction of red wine or distilled alcoholic drinks with physiological amounts of nitr...
Regulation by glucose of oscillatory electrical activity and 5-HT/insulin relea...
Rosário, Luís M.; Barbosa, Rui M.; Antunes, Célia M.; Baldeiras, Inês E.; Silva, Amélia M.; Tomé, Ângelo R.; Santos, Rosa M.The glucose sensitivity of bursting electrical activity and pulsatile insulin release from pancreatic islets was determined in absence of functional KATP channels. Membrane potential, [Ca2+]i and 5-HT/insulin release were measured by intracellular recording, fura-2 fluorescence and 5-HT amperometry, respectively. Single mouse islets, bathed in tolbutamide or glibenclamide and high extracellular Ca2+ (Ca2+o), di...
LDL Isolated from Plasma-Loaded Red Wine Procyanidins Resist Lipid Oxidation an...
Lourenço, Cátia F.; Gago, Bruno; Barbosa, Rui M.; Freitas, Víctor de; Laranjinha, JoãoDietary phenolic compounds may act as antioxidants in vitro, but because of structural modifications during absorption, its role based on concentrations high enough to afford an antioxidant protection needs to be re-evaluated. We have explored the hypothesis that red wine procyanidins interact with low density lipoproteins (LDL) and that, at this location, the phenolic compounds efficiently protect LDL from oxi...
Regulation by glucose of oscillatory electrical activity and 5-HT/insulin relea...
Antunes, Célia M.; Rosário, Luís M.; Barbosa, Rui M.; Silva, Amélia S.; Baldeiras, Inês E.; Tomé, Ângelo R.; Santos, Rosa M.The glucose sensitivity of bursting electrical activity and pulsatile insulin release from pancreatic islets was determined in absence of functional KATP channels. Membrane potential, [Ca2+]i and 5- HT/insulin release were measured by intracellular recording, fura-2 fluorescence and 5-HT amperometry, respectively. Single mouse islets, bathed in tolbutamide or glibenclamide and high extracellular Ca2+ (Ca2+o), d...
Infrared spectroscopy of racemic and enantiomeric forms of atenolol
Castro, R. A. Esteves de; Canotilho, João; Barbosa, Rui M.; Redinha, J. SimõesThe molecular structure of conformational isomorphs given by X-ray diffraction for racemic and enantiomeric atenolol were optimized at the HF/6-31G* level of theory and the infrared spectra of the structure were calculated. These spectra are used to characterize the differences between the various atenolol conformers. ; http://www.sciencedirect.com/science/article/B6VNG-4M3R2CM-5/1/b10f1bad0cbecc44994eccae4c...
Red wine-dependent reduction of nitrite to nitric oxide in the stomach
Gago, Bruno; Lundberg, Jon O.; Barbosa, Rui M.; Laranjinha, JoãoNitrite may be a source for nitric oxide (NO), particularly in highly acidic environments, such as the stomach. Diet products contribute also with reductants that dramatically increase the production of NO from nitrite. Red wine has been attributed health promoting properties largely on basis of the reductive antioxidant properties of its polyphenolic fraction. We show in vitro that wine, wine anthocyanin fract...
Conformational Isomorphism of Organic Crystals: Racemic and Homochiral Atenolol
Castro, R. A. Esteves de; Canotilho, João; Barbosa, Rui M.; Silva, M. Ramos; Beja, A. Matos; Paixão, J. A.; Redinha, J. SimõesX-ray diffraction analysis of (R,S)- and S-atenolol crystalline forms was performed. The crystals studied were grown from evaporation of an ethanol/water solution. (R,S)-Atenolol crystallizes in the centrosymmetric space group C2/c, and S-atenolol crystallizes in a noncentrosymmetric space group C2. There is one symmetry independent molecule in (R,S)-atenolol crystals and two symmetry independent molecules in S...
Electrochemical measurement of endogenously produced nitric oxide in brain slic...
Ferreira, Nuno R.; Ledo, Ana; Frade, João G.; Gerhardt, Greg A.; Laranjinha, João; Barbosa, Rui M.The role of nitric oxide (NO) as a regulatory diffusible molecule in the brain requires the evaluation of its concentration dynamics. In this work, we have developed microelectrodes suitable for real time electrochemical measurements of NO in vitro. Nafion and o-phenylenediamine were used to modify the surface of carbon fiber microelectrodes (8 [mu]m diameter; [approximate]100 [mu]m tip length). Coating with Na...
Concentration Dynamics of Nitric Oxide in Rat Hippocampal Slices
Ledo, Ana; Barbosa, Rui M.; Cadenas, Enrique; Gerhardt, Greg; Laranjinha, JoãoNitric oxide () production in response to stimulation of the NMDA glutamate receptor is implicated not only in the synaptic plasticity in hippocampus but may also participate in excitotoxic cell death. Using -selective microssensors inserted into the diffusional field of in acute hippocampal slices, we describe the concentration dynamics evoked by NMDA receptor activation and report profound differences along...
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