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211.
César IC Byrro RM Santana E Silva Cardoso FF Mundim IM Souza Teixeira L Gomes SA Bonfim RR Pianetti GA 《Journal of mass spectrometry : JMS》2011,46(9):943-948
A sensitive and fast high‐performance liquid chromatography–electrospray ionization–MS/MS method for the simultaneous quantitation of levodopa and carbidopa in human plasma was developed and validated. A simple protein precipitation step with perchloric acid was used for the cleanup of plasma, and methyldopa was added as an internal standard. The analyses were carried out using an ACE C18 column (50 × 4.6 mm i.d.; 5 µm particle size) and a mobile phase consisting of 0.2% formic acid and acetonitrile (90:10). The triple‐quadrupole mass spectrometer equipped with an electrospray source in positive mode was set up in the selective reaction monitoring mode to detect the ion transitions m/z 198.1 → m/z 107.0, m/z 227.2 → m/z 181.0, and m/z 212.1 → m/z 139.2 for levodopa, carbidopa, and methyldopa, respectively. The method was validated and proved to be linear, accurate, and precise over the range 50–5000 ng/mL for levodopa and 3–600 ng/mL for carbidopa. The proposed method was successfully applied in a pharmacokinetic study with a levodopa/carbidopa tablet formulation in healthy volunteers. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
212.
Silva FL Fischer DC Tavares JF Silva MS de Athayde-Filho PF Barbosa-Filho JM 《Molecules (Basel, Switzerland)》2011,16(2):1070-1102
Bidens pilosa L. is a cosmopolitan annual herb, known for its traditional use in treating various diseases and thus much studied for the biological activity of its extracts, fractions and isolated compounds. Polyacetylenes and flavonoids, typical metabolite classes in the Bidens genus, predominate in the phytochemistry of B. pilosa. These classes of compounds have great taxonomic significance. In the Asteraceae family, the acetylene moiety is widely distributed in the Heliantheae tribe and some representatives, such as 1-phenylhepta-1,3,5-triyne, are noted for their biological activity and strong long-wave UV radiation absorbance. The flavonoids, specifically aurones and chalcones, have been reported as good sub-tribal level markers. Natural products from several other classes have also been isolated from different parts of B. pilosa. This review summarizes the available information on the 198 natural products isolated to date from B. pilosa. 相似文献
213.
We are proposing for the first time the successful immobilization of DNA at glassy carbon electrodes (GCE) modified with carbon nanotubes (CNT) dispersed in glucose oxidase (GOx) (GCE/CNT‐GOx) either by direct adsorption or by layer‐by‐layer self‐assembling using polydiallyldimethylamine (PDDA). The presence of GOx allows an efficient dispersion of CNT and gives a most favorable environment that promotes the adsorption and makes possible a more sensitive electrooxidation of DNA. The PDDA incorporated in the self‐assembled architecture largely facilitates the adsorption and electrooxidation of dsDNA and the adsorbed layer can be successfully used for evaluating the interaction of DNA with methylene blue. 相似文献
214.
We prove that various classical tree forcings—for instance Sacks forcing, Mathias forcing, Laver forcing, Miller forcing and Silver forcing—preserve the statement that every real has a sharp and hence analytic determinacy. We then lift this result via methods of inner model theory to obtain level-by-level preservation of projective determinacy (PD). Assuming PD, we further prove that projective generic absoluteness holds and no new equivalence classes are added to thin projective transitive relations by these forcings. 相似文献
215.
Fausto N. Comba Fabiana Gutierrez Pilar Herrasti María D. Rubianes Gustavo A. Rivas 《Electroanalysis》2012,24(7):1541-1546
This work reports the effect of the incorporation of different proteins within carbon paste electrodes (CPE) modified with electrochemically synthesized magnetite nanoparticles (20 nm) on the electrochemical response towards hydrogen peroxide. Scanning electron microscopy images reveal that the proteins produce a more efficient dispersion of the nanoparticles within the composite. When CPE is modified with 5.0 % w/w magnetite and 5.0 % w/w albumin the sensitivity for hydrogen peroxide at ?0.100 V is enhanced 40 times and the charge transfer resistance significantly decreases. The increase in sensitivity and the decrease in Rct was dependent on the nature of the protein. 相似文献
216.
Salvatore Nesci Vittoria Ventrella Fabiana Trombetti Maurizio Pirini Alessandra Pagliarani 《应用有机金属化学》2012,26(11):593-599
In mussel digestive gland mitochondria the environmental pollutant tri‐n‐butyltin (TBT), other than strongly inhibiting ATPase activity at <1.0 μ m , at ≥1.0 μ m concentration was previously found to desensitize F1FO‐ATPase to the antibiotic oligomycin. While F1FO‐ATPase inhibition is widely known as one of the main mitochondrial damages caused by TBT, the enzyme's desensitization to oligomycin was quite unexpected. The possible mechanisms involved are here stepwise approached, aiming at enlightening the molecular mechanism(s) of TBT toxicity and the still poorly investigated oligomycin interaction with FO. The findings strongly suggest that the oligomycin desensitization directly stems from the covalent binding of TBT to monothiols of the F1FO‐ATPase. This binding implies sulfur oxidation, irrespective of the possible formation of radical species in mitochondria, a mechanism which does not seem to be involved here. It is hypothesized that TBT interacts with the enzyme complex in at least two sites distinguished by different affinities: TBT binding to the high‐affinity site would lead to ATPase inhibition, while TBT binding to monothiols in the low‐affinity site could mirror the decrease in F1FO‐ATPase oligomycin sensitivity at ≥1.0 μ m TBT. Experiments carried out on inside‐out submitochondrial particles hint that TBT binding destabilizes the oligomycin‐blocked FO conformation, allowing proton flux recovery within FO, without uncoupling the catalytic function from proton channeling. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
217.
Fabiana Inoue Rmulo Augusto Ando Paola Corio 《Journal of Raman spectroscopy : JRS》2011,42(6):1379-1383
Nanocomposites of carbon nanotubes and titanium dioxide (TiO2) have attracted much attention due to their photocatalytic properties. Although many examples in the literature have visualized these nanocomposites by electron microscopic images, spectroscopic characterization is still lacking with regard to the interaction between the carbon nanotube and TiO2. In this work, we show evidence of the attachment of nanostructured TiO2 to multiwalled carbon nanotubes (MWNTs) by Raman spectroscopy. The nanostructured TiO2 was characterized by both full‐width at half‐maximum (FWHM) and the Raman shift of the TiO2 band at ca 144 cm−1, whereas the average diameter of the crystallite was estimated as approximately 7 nm. Comparison of the Raman spectra of the MWNTs and MWNTs/TiO2 shows a clear inversion of the relative intensities of the G and D bands, suggesting a substantial chemical modification of the outermost tubes due to the attachment of nanostructured TiO2. To complement the nanocomposite characterization, scanning electronic microscopy and X‐ray diffraction were performed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献