Systematic review and meta-analysis on the role of mitochondrial cytochrome c oxidase in Alzheimer's disease.

OBJECTIVE: The present study was designed to test the hypothesis that there is a reduction in the activity of the enzyme cytochrome c oxidase (Cox) in Alzheimer's disease (AD). METHODS: Systematic review of literature and meta-analysis were used with data obtained from the PubMed, Scopus, MEDLINE, Lilacs, Eric and Cochrane. The keywords were Alzheimer's AND Cox AND mitochondria; Alzheimer's AND Cox AND mitochondria; Alzheimer's AND complex IV AND mitochondria. A total of 1372 articles were found, 23 of them fitting the inclusion criteria. The data were assembled in an Excel spreadsheet and analysed using the RevMan software. A random effects model was adopted to the estimative of the effect. RESULTS: The data shows a significant decrease in the activity of the Cox AD patients and animal models. CONCLUSION: Cox enzyme may be an important molecular component involved in the mechanisms underlying AD. Therefore, this enzyme may represent a possible new biomarker for the disease as a complementary diagnosis and a new treatment target for AD.

Toxicity assessment of 2,4-D and MCPA herbicides in primary culture of fish hepatic cells.

In this study, we used primary cultures of fish hepatic cells as a tool for evaluating the effects of environmental contamination. Primary hepatic cell cultures derived from the subtropical fish Metynnis roosevelti were exposed to different concentrations (0.275, 2.75 and 27.5 µg L(-1)) of the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA). Cellular respiratory activity was evaluated by polarography using three substrates: 0.5 M glucose, 0.5 M succinate and 0.5 M α-ketoglutarate. Significant changes were observed in cellular oxygen consumption with 0.5 M α-ketoglutarate. Even at low concentrations, 2,4-D and MCPA were potent uncouplers of oxidative phosphorylation. Primary cultures of M. roosevelti liver cells may provide a useful tool for the evaluation of environmental contaminant effects. A review of regulations regarding permitted concentrations of these herbicides is needed.

Selective polarographic determination of stannous ion in technetium radiopharmaceutical cold kits.

UNLABELLED: The aim of this work was to develop a selective method for quantification of Sn(II) and Sn(IV) in dimercaptosuccinic acid (DMSA), ethylcysteinate dimer (ECD), methylenediphosphonic acid (MDP), and pyrophosphate radiopharmaceutical cold kits by differential pulse polarography. METHODS: A dripping mercury electrode 150 polarographic/stripping analyzer with a conventional 3-electrode configuration was used with 3 M H(2)SO(4) and 3 M HCl supporting electrolytes for Sn(II) and Sn(IV), respectively. The polarographic analysis was performed using a 1-s drop time, 50-mV·s(-1) scan rate, -50-mV pulse amplitude, 40-ms pulse time, and 10-mV step amplitude. To quantify Sn(IV), oxidation of Sn(II) by H(2)O(2) was performed. The calibration curves for Sn(II) and Sn(IV) were obtained in the range of 0-10 µg·mL(-1). RESULTS: The analytic curves for Sn(II) in 3 M H(2)SO(4) and Sn(IV) in 3 M HCl were represented by the following equations: i (µA) = 0.098 [Sn(II)] + 0.018 (r(2) = 0.998) and i (µA) = 0.092 [Sn(IV)] + 0.016 (r(2) = 0.998), respectively. The detection limits were 0.21 µg·mL(-1) for Sn(II) and 0.15 µg·mL(-1) for Sn(IV). In DMSA, ECD, MDP, and pyrophosphate, 90.0%, 64.9%, 93.2%, and 87.5%, respectively, of the tin was present as Sn(II). In this work, selective determination of Sn(II) and Sn(IV) was achieved using 2 supporting electrolytes (H(2)SO(4) and HCl). In 3 M H(2)SO(4), only Sn(II) produced a polarographic wave with the maximum current in -370 mV. Under the same conditions, no current could be determined for Sn(IV). In 3 M HCl, Sn(II) and Sn(IV) were electroactive and the maximum currents of the 2 waves appeared in -250 and -470 mV. No other components of the lyophilized reagents had any influence. CONCLUSION: The developed polarographic method was adequate to quantify Sn(II) and Sn(IV) in DMSA, ECD, MDP, and pyrophosphate cold kits.

A review of analytical techniques for determination of glimepiride: present and perspectives.

Glimepiride is an oral antidiabetic drug in the sulfonylurea class, which is widely used in treatment of Type 2 diabetes and it is currently available in more than 60 countries worldwide. As a result of the importance of this oral hypoglycemic agent in the treatment of noninsulin-dependent diabetes mellitus, this work aims to compile the published analytical methods reported so far in the literature for determination of glimepiride in biologic samples and pharmaceutical formulations. Techniques like high-performance liquid chromatography with ultraviolet, array-diode, mass spectroscopy, evaporative light scattering and charged aerosol detections, liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry, liquid chromatography-electrospray ionization-tandem mass spectrometry, semimicrobore high-performance liquid chromatography with column-switching, micellar electrokinetic chromatography, high-performance thin layer chromatography, polarography, and spectrophotometry have been used for analysis, from which it can be seen that high-performance liquid chromatography methods have been used most extensively.

Determination of hydrazine in a meningococcal C conjugate vaccine intermediary product.

In Brazil, polysaccharide-protein conjugate vaccine against Neisseria meningitidis group C (MenCPS-TT) using hydrazine-activated-tetanus toxoid (TT) as a carrier protein has been developed. Because of the toxicity of hydrazine in humans, it is necessary to monitor this substance's process control step during the vaccine production. The electroanalytical methodology was developed and validated for the determination of hydrazine during the process control of MenCPS-TT vaccine production by differential pulse polarography. The reduction potential was -0.95 V in acetone and sulphuric acid solution. The method presented linear range between 30 and 150 microgL(-1)and recovery of 93.5+/-0.8%.

Voltammetric behavior of zaleplon and its differential pulse polarographic determination in capsules.

In this work both the electrochemical behavior and the analysis of the hypnotic pyrazolopyrimidine derivative zaleplon were studied. Zaleplon in ethanol-0.1M Britton Robinson buffer solution (30-70) showed 2 irreversible, well-defined cathodic responses in the pH range of 2-12 using differential pulse polarography (DPP), tast polarography, and cyclic voltammetry. From chronocoulometric studies, it was possible to conclude that one electron was transferred in each reduction peak or wave. For analytical purposes, the DPP technique working at pH 4.5 for peak I was selected, which exhibited adequate repeatability, reproducibility, and selectivity. The recovery was 99.97 +/- 1.52%, and the detection and quantitation limits were 5.13 x 10(-7)M and 1.11 x 10(-6)M, respectively. The DPP method was applied successfully to the individual assay of capsules in order to verify the content uniformity of zaleplon. Treatment of the sample is not required because the excipients do not interfere, the method is not time consuming, and it is less expensive than column liquid chromatography.

Differential pulse polarographic determination of clotrimazole after derivatization with Procion Red HE-3B.

Clotrimazole was shown to react at room temperature in Britton Robinson buffer pH 2 with the reactive dye Procion Red HE-3B. The product exhibited a differential pulse polarographic peak at -0.38 V, which was well separated from the peaks of the reactive dye at -0.08, -0.80 and -0.95 V, and this allowed the indirect determination of clotrimazole in the presence of excess of the reactive dye. The method has been applied satisfactorily to the determination of clotrimazole in pharmaceutical formulations, calibration graphs are rectilinear up to at least 40 microg ml(-1). The detection limit was calculated to be 2.6 microg ml(-1) (3 sigma).

Determination of niobium in pyrochlore ore by differential pulse polarography.

A differential pulse polarographic method has been developed for the quantitative determination of niobium in pyrochlore ore. One-step polarographic curves were obtained in 0.01 mol L(-1) EDTA as supporting electrolyte. Analytical curves indicated that response was linearly dependent on Nb(V) concentration between 1.6 and 8.6 mg L(-1) in the pH range 2-5. The system is quasi-reversible and controlled by diffusion in 0.01 mol L(-1) EDTA as supporting electrolyte; the electrode process involves one-electron reduction of Nb(V) to Nb(IV). The results obtained so far for niobium in pyrochlore ore were comparable with those obtained by X-ray fluorescence determination. Ions such as Fe(III), Cr(III), As(III), Cu(II), Ni(II), Co(II), Mn(II), Sn(IV), Zn(II), V(V), Ta(V), W(VI), Ce(IV), and Ti(IV) did not interfere. Possible interference from Pb(II) can be avoided by complexation with the supporting electrolyte in the pH range 3.5 to 4.6; Mo(VI) ions can be tolerated when their concentration is one-tenth that of Nb(V).

Indirect polarographic and cathodic stripping voltammetric determination of cefaclor as an alkaline degradation product.

Cefaclor is not reducible at a mercury electrode, but it can be determined polarographically and by cathodic stripping voltammetry as its initial alkaline degradation product which is obtained in high yield by hydrolysis of cefaclor in Britton-Robinson (B-R) buffer pH 10 at 50 degrees C for 30 min (reduction peak at pH 10, -0.70 V). Differential pulse polarographic calibration graphs are linear up to at least 1 x 10(-4) mol/l(-1). Recoveries of 93% of the cefaclor (n = 3) were obtained from urine spiked with 38.6 microg/ml(-1) using this polarographic method with 1 ml urine made up to 10 ml with pH 10 buffer. Using cathodic stripping voltammetry and accumulating at a hanging mercury drop electrode at - 0.2 V for 30 s, linear calibration graphs were obtained from 0.35 to 40 microg/ml(-1) cefaclor in B-R buffer pH 10. A relative standard deviation of 4.2% (eta = 5) was obtained, and the limit of detection was calculated to be 2.9 ng/ml(-1). Direct determination of cefaclor in human urine (1 ml of urine was made up to 10 ml with pH 10 buffer) spiked to 0.39 microg/ml(-1) was made (recovery 98.6%).

Automated polarographic determination of sulfide as contaminant in parenteral amino acid solutions.

A method for the automated polarographic determination of sulfide in a gas-diffusion flow system was developed. The volatile sulfide, existing as a contaminant in parenteral amino acid solutions, was measured after gas diffusion using 0.1 mol l-1 NaOH solution as acceptor. The linear range of calibration, for measurements at a dropping-mercury electrode (DME), was from 5 to 100 micrograms of sulfide with r = 0.999 and RSD = 7.5% (n = 5) for 10 micrograms of sulfide. For measurements at the hanging mercury-drop electrode (HMDE), with a preconcentration time of 30 s, the linear range of calibration was from 0.9 to 20 micrograms of sulfide with r = 0.998 and RSD = 5.8% (n = 5) for 2 micrograms of sulfide. Detection limits of 59 and 11 micrograms l-1 at the DME and HMDE, respectively, were calculated and the recoveries of sulfide from spiked samples were 91.5-104.5%. Parameters that affect the sulfide determination using this method, such as the organic content of the matrix, pH, flow rate and sample size, were investigated.

Effect of aliphatic aldehydes on the lipid peroxidation and chemiluminescence of biological systems under oxidative stress.

The effect of several aliphatic aldehydes on lipid peroxidation was evaluated by measuring the oxygen uptake rate, thiobarbituric acid-reactive products formation and the emitted visible chemiluminescence intensity. Measurements were carried out in brain homogenates and erythrocyte plasma membrane and liver microsomal fractions. In all systems studied, aldehydes (25 mmol/L) (e.g. acetaldehyde, 2,2-dimethylpropanal), increased the intensity of the luminescence associated with the oxidation process. In contrast, aldehyde incorporation decreased TBARS production and the rate of oxygen uptake. The increased luminescence intensity is explained in terms of secondary reactions of aldehyde derived free radicals. These results clearly indicate that extreme care must be exercised in the interpretation of chemiluminescence data in the presence of aldehydes.

Redox behaviour of nifuroxazide: generation of the one-electron reduction product.

The electrochemical properties of nifuroxazide have been investigated in aqueous and aqueous-DMF mixed solvents. In aqueous media, a single, irreversible four-electron reduction occurs to give the hydroxylamine derivative. In mixed media, a reversible one-electron reduction to form a nitro radical anion takes place. Cyclic voltammetric studies show that the anion radical product is stable, although the nitro radical anion intermediate shows a tendency to undergo further chemical reactions. A comparison with the voltammetric behaviour of other nitrofurans such as nifurtimox, nitrofurazone and furazolidone is made. The electrochemically-obtained parameters are correlated with the in vivo studies of oxygen consumption on Trypanosoma cruzi cell suspensions.

Evaluation of the polarographic technique for assay of the viability of freeze-dried BCG vaccine: I. The polarographic technique.

In this paper, a new assay based on oxygen uptake assessed by polarography was evaluated with the aim of establishing the viability of freeze-dried BCG vaccine. An oxygen electrode possessing a temperature sensor was designed for this purpose. The polarographic method used had several advantages, particularly its rapidity and use of small amounts of biological material. These advantages are ideal for quality control of BCG vaccine.

Evaluation of the polarographic technique for assay of the viability of freeze-dried BCG vaccine: II. Viability of the vaccine assessed by polarography, Warburg respirometry and colony counting.

A comparative study of the viability of 34 lots of freeze-dried BCG vaccine has been carried out using an oxygen electrode polarographic technique, Warburg respirometry and colony counting. There were no statistical differences between the results obtained with the polarographic and Warburg techniques. Both methods gave reliable and similar results and showed a positive correlation (r = 0.8615). Comparison between the polarographic and colony-counting methods showed a positive correlation (r = 0.6530); for comparison between the Warburg and colony-counting methods, the correlation value was r = 0.6868. All the tests were significant at the level of alpha = 0.05. The advantages of the polarographic technique are that it is much less time- and material-consuming than other methods. It is a reliable, inexpensive and convenient method for BCG vaccine quality control.

Empleo de la polarografía de pulso diferencial en el análisis de impurezas metálicas en muestras farmacéuticas. III / Use of differential pulse polarography in the analysis of etallic impurities in pharmaceutical samples: III

Se desarrollan procedimientos generales aplicables para la determinación simultánea de impurezas de cobre, plomo, cadmio y cinc en muestras farmacéuticas que incluyen materias primas insolubles, tabletas de ácido acetilsalicílico y similares, y materiales plásticos de uso en farmacia, con el empleo de la polarografía de pulso diferencial. La posibilidad que ofrece este método de detectar y cuantificar de forma individual esos iones en una sola determinación, a lo que se le unen otras ventajas como son rapidez y bajo costo, lo presenta como una alternativa importante del análisis global y semicuantitativo por precipitación de sulfuros, que tradicionalmente se ha prescrito como prueba oficial por las diferentes farmacopeas

Empleo de la polarografía de pulso diferencial en el análisis de impurezas metálicas en muestras farmacéuticas: III / Use of differential pulse polarography in the analysis of metallic impurities in pharmaceutical samples: III

Se desarrollan procedimientos generales aplicables para la determinación simultánea de impurezas de cobre, plomo, cadmio y cinc en muestras farmacéuticas que incluyen materias primas insolubles, tabletas de ácido acetilsalicílico y similares, y materiales plásticos de uso en farmacia, con el empleo de la polarografía de pulso diferencial. La posibilidad que ofrece este método de detectar y cuantificar de forma individual esos iones en una sola determinación, a lo que se le unen otras ventajas como son rapidez y bajo costo, lo presenta como una alternativa importante del análisis global y semicuantitativo por precipitación de sulfuros, que tradicionalmente se ha prescrito como prueba oficial por las diferentes farmacopeas

[A cholinergic participation in the increase of cerebral cortical blood flow induced by vincamine (rat) (author's transl)]. / Participación colinérgica en el aumento de flujo cortical cerebral inducido por la vincamina.

The effect of vincamine on cortical blood flow was tested in control rats and after atropine administration. Cortical blood flow was measured in urethanized rats by means of the hydrogen clearance method. A significative increase in cortical blood flow and decrease in blood pressure and cortical vascular resistance was produced by vincamine iv administration in control animals. In atropinized rats significative cortical blood flow changes were not observed although some tendency to increase was detected. It is suggested that increase in cortical blood flow induced by vincamine may be due to direct action on the vascular smooth muscle and, partially, through a cholinergic mechanism.