Development of an amperometric biosensor based on glutathione peroxidase immobilized in a carbodiimide matrix for the analysis of reduced glutathione from serum

The development of an amperometric biosensor for the reduced glutathione determination in serum is described, The biosensor is based on glutathione peroxidase (GSH-Px, EC 1.11.1.9) immobilized onto a pyrolytic graphite-working electrode using carbodiimide as enzymatic condensing reagent. This resulted in an amperometric biosensor with good sensitivity and stability. The reduced glutathione (GSH) was enzymatically converted to glutathione disulfide (GSSG) in the presence of hydroperoxide. which was monitored amperometrically by its electrooxidation at +0.65 V vs. SCE (saturated calomel electrode). Glutathione measurement was carried out by maintaining the ratio between GSH and hydrogen peroxide at 2:1 (25 degreesC), The amperometric response of the biosensor was linearly proportional to the GSH concentration between 1.9 X 10(-5) and 1.4 X 10(-4) mol/l, in 0.1 mol/l phosphate buffer (pH = 7.8), containing 0.1 mol/l KCI and 0.5 mmol/l Na(2)H(2)EDTA, as the supporting electrolyte, In presence of interfering compounds, the recoveries ranged between 97.2% and 110.7%. The biosensor useful lifetime was at least 2 months when it was evaluated after continuous use. Serum samples analyzed by this biosensor showed a good correlation with the results from the spectrophotometric method (Ellman's reagent) used as reference, presenting relative deviations lower than 7.0%. The low apparent Michaelis-Menten constant value. K-M(app) = 1.6 mmol/l. demonstrated that GSH-Px immobilized on pyrolytic graphite exhibited a high affinity to GSH, without loss of enzymatic activity. (C) 2001 Elsevier Science B.V. All rights reserved.30841671556

Synthesis of some new neostigmine methyl sulphates and related compounds

56218118

Blood Calcium Levels in Immature Rats: Influence of Extracellular Calcium Concentration on Myocardial Calcium Handling

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Calcium ions play an important role in several cell functions, from fertilization to cell death. The cytosolic Ca2+ concentration is much lower than the extracellular concentration ([Ca2+](o)). The latter may markedly affect Ca2+ fluxes across the cell membrane and thus the cellular Ca2+ load. Thus, when working with preparations in vitro, it is important to keep [Ca2+](o) close to the in vivo value. In this study, we determined the calcemia in immature rats, for which values are currently unavailable, and investigated how supraphysiological [Ca2+](o) affects myocardial Ca2+ handling. Blood ionized [Ca2+] was similar in neonatal (2-5 days old) and adults Wistar rats (1.28 +/- 0.03 and 1.31 +/- 0.03 mmol/l; n=6 and 5, respectively, P>0.37), and lower than the [Ca2+](o) range often used in experiments with neonatal myocardial preparations. Cytosolic Ca2+ transients, measured with indo-1 in neonatal ventricular myocytes, were enhanced by an increase in [Ca2+](o) from 1.2 to 2 mM, which also increased the Ca2+ content in the sarcoplasmic reticulum (SR), and changed the pattern of competition between the main transporters that remove Ca2+ from the cytosol (SR Ca2+-ATPase and Na+/Ca2+ exchanger). These observations stress the importance of using physiological [Ca2+](o) values for reliability of results. It is expected that the present calcemia data, reported for the first time in immature rats, may contribute to the refinement of in vitro experiments with neonatal rat preparations.614399405Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [N. 2008/54795-6

Direct monitoring of drug degradation by easy ambient sonic-spray ionization mass spectrometry: the case of enalapril

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Using enalapril maleate as a test case, the ability of ambient mass spectrometry, namely, via easy ambient sonic-spray ionization mass spectrometry (EASI-MS), to perform direct monitoring of drug degradation has been tested. Two manufacturing processes were investigated (direct compression and wet granulation), and the formation of degradation products was measured via both EASI-MS and high-performance liquid chromatography with ultraviolet detection for a total period of 18 months. Both techniques provide comparable results, which indicate that direct analysis by ambient mass spectrometric techniques presents a viable alternative for drug degradation monitoring with superior simplicity, throughput, and reliability (no sample manipulation), and comparable quantitative results. In terms of qualitative monitoring, the full mass spectra with intact species provided by EASI-MS allow for comprehensive monitoring of known and unknown (or unexpected) degradation products. Copyright (C) 2011 John Wiley & Sons, Ltd.46121269U27Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Assignments of (1)H and (13)C NMR spectral data for benzoylecgonine, a cocaine metabolite

The complete assignment of the (1)H and (13)C NMR spectra of benzoylecgonine, a cocaine metabolite, was performed, with the aid of some 2D experiments such as gCOSY and gHSQC.41310110

Synthesis of some new o-substituted arylcarbamates and related compounds

Seven new 2-substituted-5-N',N'-dimethylaminophenyl N,N-dimethylcarbamates and three other compounds of similar structures have been synthesized aiming at obtaining potent anti-ChE agents. It has been found that the 2-substituents, regardless of their character, decrease the biological activity of the carbamates. (C) 1997 Academic Press.251374

THE INFRARED-SPECTRA OF DIARYLTELLURIUM DICARBOXYLATES

581475

Direct determination of potassium in human blood serum by flow injection flame photometry with automatic dilution

A method was developed for the automatic quantitative determination of potassium in serum: by flow injection analysis. The serum sample is directly introduced in the flow. The dilution with deionized water stream is done automatically acid sequentially in the system to reach the adequate concentration to be introduced in the flame photometer. The results achieved with this method, for serum samples obtained in the Hospital of the University, had been compared with those values of the Hospital laboratory that uses manual dilution and flame photometry. The results obtained by the two methods agree within at least +/-5%. About 60 samples/hour can be easily analyzed by the method proposed in this work.29101719172

Synthesis and application of a peroxidase-like molecularly imprinted polymer based on hemin for selective determination of serotonin in blood serum

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This work reports the preparation of a molecularly imprinted polymer (MIP) for selective catalytic detection of serotonin (5-hydroxytryptamine, 5-HT). The process is based on the synthesis of polymers with hemin introduced as the catalytic center to mimic the active site of peroxidase. The copolymer MIP, containing artificial recognition sites for 5-HT, has been prepared by bulk polymerization using methacryl' acid (MAA) and hemin as the functional monomers, and ethylene glycol climethacrylate (EGDMA) as the cross-linker. For the determination of 5-HT, a flow injection analysis system coupled to an amperometric detector was optimized using multivariate analysis. The effects of different parameters, such as pH, buffer flow rate, buffer nature, peroxide concentration and sample volume were evaluated. After optimizing the experimental conditions, a linear response range from 1.0 up to 1000.0 mu mol L(-1) was obtained with a sensitivity of 0.4 nA/mu mol L(-1). The detection limit was found to be 0.30 mu mol L(-1), while the precision value (n = 6) evaluated by relative standard deviation (R.S.D.) were, respectively, 1.3 and 1.7% for solutions of 50 and 750 mu mol L(-1) of 5-HT. No interference was observed by structurally similar compounds (including epinephrine, cloparnine and norepinephrine), thus validating the good performance of the imprinted polymer. The method was applied for the determination of 5-HT in spiked blood serum samples. (C) 2008 Elsevier B.V. All rights reserve.6312170176Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Cientifico e Tecnol6gico (CNPc)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP