Voltammetric sensor for amoxicillin determination in human urine using polyglutamic acid/glutaraldehyde film

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Potentiometric Sensor for Furosemide Determination in Pharmaceuticals, Urine, Blood Serum and Bovine Milk

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Screening of filamentous fungi for production of enzymes of biotechnological interest

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lipid peroxidation, antioxidant enzymes and glutathione levels in human erythrocytes exposed to colloidal iron hydroxide in vitro

The free form of the iron ion is one of the strongest oxidizing agents in the cellular environment. The effect of iron at different concentrations (0, 1, 5, 10, 50, and 100 µM Fe3+) on the normal human red blood cell (RBC) antioxidant system was evaluated in vitro by measuring total (GSH) and oxidized (GSSG) glutathione levels, and superoxide dismutase (SOD), catalase, glutathione peroxidase (GSH-Px) and reductase (GSH-Rd) activities. Membrane lipid peroxidation was assessed by measuring thiobarbituric acid reactive substance (TBARS). The RBC were incubated with colloidal iron hydroxide and phosphate-buffered saline, pH 7.45, at 37oC, for 60 min. For each assay, the results for the control group were: a) GSH = 3.52 ± 0.27 µM/g Hb; b) GSSG = 0.17 ± 0.03 µM/g Hb; c) GSH-Px = 19.60 ± 1.96 IU/g Hb; d) GSH-Rd = 3.13 ± 0.17 IU/g Hb; e) catalase = 394.9 ± 22.8 IU/g Hb; f) SOD = 5981 ± 375 IU/g Hb. The addition of 1 to 100 µM Fe3+ had no effect on the parameters analyzed. No change in TBARS levels was detected at any of the iron concentrations studied. Oxidative stress, measured by GSH kinetics over time, occurs when the RBC are incubated with colloidal iron hydroxide at concentrations higher than 10 µM of Fe3+. Overall, these results show that the intact human RBC is prone to oxidative stress when exposed to Fe3+ and that the RBC has a potent antioxidant system that can minimize the potential damage caused by acute exposure to a colloidal iron hydroxide in vitro.

Accuracy of simple urine tests for diagnosis of urinary tract infections in low-risk pregnant women

Alterações anatômicas e fisiológicas da gravidez predispõem gestantes a infecções do trato urinário (ITU). O objetivo deste estudo foi identificar a acurácia do exame de urina simples para diagnóstico de ITU em gestantes de baixo risco. Fez-se uso do estudo de desempenho de teste diagnóstico realizado em Botucatu, SP, com 230 gestantes, entre 2006 e 2008. Os resultados mostram que a prevalência de ITU foi de 10%. A sensibilidade foi 95,6%, especificidade 63,3% e acurácia 66,5% do exame de urina simples, em relação ao diagnóstico de ITU. A análise dos valores preditivos positivo e negativo (VPP e VPN) mostrou que, na vigência de exame de urina simples normal, a chance de haver ITU foi pequena (VPN 99,2%). Frente ao resultado alterado desse exame, a probabilidade de haver ITU foi baixa (VPP 22,4%). Conclui-se que a acurácia do exame de urina simples como meio diagnóstico de ITU foi baixa, sendo indispensável a realização de urocultura para o diagnóstico.

Effect of broiler breeder age on pancreas enzymes activity and digestive tract weight of embryos and chicks

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cathodic stripping voltammetric determination of ceftazidime in urine at a hanging mercury drop electrode

A method was developed for the differential-pulse cathodic stripping voltammetric determination of ceftazidime with a hanging mercury drop electrode using its reduction peak at -0.43 V in Britton-Robinson buffer pH 4.0. The optimum accumulation potential and time were -0.15 V and up to 60 s, respectively. Linear calibration graphs were obtained from 1 x 10(-8) M and 1.5 x 10(-7) M. The limit of determination was calculated to be 5 x 10(-9) M. The coefficient of variation was 4% (n = 7) at 1 x 10(-7) M ceftazidime. The effect of various components of urine on the voltammetric response was studied, and creatinine, uric acid, urea, and glucose were shown to interfere in the method. Ceftazidime bound to human albumin gives a unique stripping peak at -0.48 V. Recoveries of 87% +/- 2% of the ceftazidime (n = 5) were obtained from urine spiked with 1.27 mu g ml(-1) using C-18 solid phase extraction cartridges. (C) 1997 Academic Press.

Anodic stripping voltammetric determination of aurothiomalate in urine using a screen-printed carbon electrode

This work describes an electroanalytical method for determining gold(I) thiomalate, aurothiomalate, widely used for treatment of reumatoid arthiritis, using a screen-printed carbon electrode (SPCE). Aurothiomalate (AuTM) was determined indirectly at the same electrode by accumulating it first at -1.5 V vs. printed carbon. At this potential in the adsorbed state, the AuTM is reduced to Au(0), which is then oxidized at two steps at -0.22 V and +0.54 V on SPCE. Using optimized conditions of 60 s deposition time, -1.5 V (vs. printed carbon) accumulation potential, 100 mV s(-1) scan rate, linear calibration graphs can be obtained by monitoring the peak at +0.54 V for AuTM in HCl 0.1 mol L-1 from 1.43 x 10(-6) to 1.55 x 10(-4) mol L-1. A limit of detection obtained was 6.50 x 10(-7) mol L-1, and the relative standard deviation from five measurements of 3.0 x 10(-5) mol L-1 AuTM is 4.5%. The method was successfully applied for AuTM determination in human urine sample.

Crystallographic and pre-steady-state kinetics studies on binding of NADH to wild-type and isoniazid-resistant enoyl-ACP(CoA) reductase enzymes from Mycobacterium tuberculosis

An understanding of isoniazid (INH) drug resistance mechanism in Mycobacterium tuberculosis should provide significant insight for the development of newer anti-tubercular agents able to control INH-resistant tuberculosis (TB). The inhA-encoded 2-trans enoyl-acyl carrier protein reductase enzyme (InhA) has been shown through biochemical and genetic studies to be the primary target for INH. In agreement with these results, mutations in the inhA structural gene have been found in INH-resistant clinical isolates of M. tuberculosis, the causative agent of TB. In addition, the InhA mutants were shown to have higher dissociation constant values for NADH and lower values for the apparent first-order rate constant for INH inactivation as compared to wild-type InhA. Here, in trying to identify structural changes between wild-type and INH-resistant InhA enzymes, we have solved the crystal structures of wild-type and of S94A, I47T and I21V InhA proteins in complex with NADH to resolutions of, respectively, 2.3 angstrom, 2.2 angstrom, 2.0 angstrom, and 1.9 angstrom. The more prominent structural differences are located in, and appear to indirectly affect, the dinucleotide binding loop structure. Moreover, studies on pre-steady-state kinetics of NADH binding have been carried out. The results showed that the limiting rate constant values for NADH dissociation from the InhA-NADH binary complexes (k(off)) were eleven, five, and tenfold higher for, respectively, I21V, I47T and S94A INH-resistant mutants of InhA as compared to INH-sensitive wildtype InhA. Accordingly, these results are proposed to be able to account for the reduction in affinity for NADH for the INH-resistant InhA enzymes. (c) 2006 Elsevier Ltd. All rights reserved.

Determination of herbicides and a metabolite in human urine by liquid chromatography-electrospray ionization mass spectrometry

A method was developed to determine simazine, atrazine and their metabolite, 2-chloro-4,6-diamino-1,3,5-triazine, in urine. The presence of these herbicides in urine may reflect possible exposure to pesticides. Sample preparation involved protein precipitation and solid-phase extraction. The samples were analyzed by high-performance liquid chromatography-mass spectrometry. The detection limits were 0.4 mug/l and the analytes have a linear response in the interval 6-800 mug/l. The precision of the method was reflected in the RSD of <2.4% for the herbicides studied. Based on the detectable herbicide levels from spiked urine samples collected from unexposed volunteers, this method can be used to determine the low levels necessary for establishing reference values of the selected herbicides and the metabolite. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Influence of temperature on the properties of the xylanolytic enzymes of the thermotolerant fungus Aspergillus phoenicis

This study reports on the effects of growth temperature on the secretion and some properties of the xylanase and beta-xylosidase activities produced by a thermotolerant Aspergillus phoenicis. Marked differences were observed when the organism was grown on xylan-supplemented medium at 25 degreesC or 42 degreesC. Production of xylanolytic enzymes reached maximum levels after 72 h of growth at 42 degreesC; and levels were three- to five-fold higher than at 25 degreesC. Secretion of xylanase and beta-xylosidase was also strongly stimulated at the higher temperature. The optimal temperature was 85 degreesC for extracellular and 90 degreesC for intracellular beta-xylosidase activity, independent of the growth temperature. The optimum temperature for extracellular xylanase increased from 50 degreesC to 55 degreesC when the fungus was cultivated at 42 degreesC. At the higher temperature, the xylanolytic enzymes produced by A. phoenicis showed increased thermo stability, with changes in the profiles of pH optima. The chromatographic profiles were distinct when samples obtained from cultures grown at different temperatures were eluted from DEAE-cellulose and Biogel P-60 columns.