Salivary Parameters (Salivary Flow, pH and Buffering Capacity) in Stimulated Saliva of Mexican Elders 60 Years Old and Older.

OBJECTIVE: To compare a limited array of chewing-stimulated saliva features (salivary flow, pH and buffer capacity) in a sample of elderly Mexicans with clinical, sociodemographic and socio-economic variables. SUBJECTS AND METHODS: A cross-sectional study was carried out in 139 adults, 60 years old and older, from two retirement homes and a senior day care centre in the city of Pachuca, Mexico. Sociodemographic, socio-economic and behavioural variables were collected through a questionnaire. A trained and standardized examiner obtained the oral clinical variables. Chewing-stimulated saliva (paraffin method) was collected and the salivary flow rate, pH and buffer capacity were measured. The analysis was performed using non-parametric tests in Stata 9.0. RESULTS: Mean age was 79.1 ± 9.8 years. Most of the subjects included were women (69.1%). Mean chewing-stimulated salivary flow was 0.75 ± 0.80 mL/minute, and the pH and buffer capacity were 7.88 ± 0.83 and 4.20 ± 1.24, respectively. Mean chewing-stimulated salivary flow varied (p < 0.05) across type of retirement home, tooth brushing frequency, number of missing teeth and use of dental prostheses. pH varied across the type of retirement home (p < 0.05) and marginally by age (p = 0.087); buffer capacity (p < 0.05) varied across type of retirement home, tobacco consumption and the number of missing teeth. CONCLUSIONS: These exploratory data add to the body of knowledge with regard to chewing-stimulated salivary features (salivary flow rate, pH and buffer capacity) and outline the variability of those features across selected sociodemographic, socio-economic and behavioural variables in a group of Mexican elders.

Solid-contact Hg(II)-selective electrode based on a carbon-epoxy composite containing a new dithiophosphate-based ionophore.

The experimental results herein concern a novel ion-selective electrode manufactured with an inner solid contact based on a new ligand O,O'-(2,2'-biphenylene)dithiophosphate pentyl (PenDTF). This electrode displays high selectivity toward the Hg(II) ion even in the presence of different divalent ions. The electrode also exhibited a good Nernstian response to Hg(II) (33.7±1.0 mV decade(-1)) over an ample concentration range (5.3×10(-7)-1.0×10(-2) mol L(-1)), with a detection limit of (6.1±1.7)×10(-7) mol L(-1). As a result of design, the electrode can be used for many experiments, simply renewing its contact surface with emery paper, without giving rise to a significant response deviation, exhibiting a variation coefficient of 3%, capable of being tested within the 0-5 pH interval. The electrode was used satisfactorily as indicating electrode during the potentiometric titration of Hg(II) ions with EDTA.

Nucleation and growth kinetics of electrodeposited sulfate-doped polypyrrole: determination of the diffusion coefficient of SO(4)(2-) in the polymeric membrane.

A kinetic study for the electrosynthesis of polypyrrole (Ppy) doped with SO(4)(2-) ions is presented. Ppy films were electrochemically polymerized onto a graphite-epoxy resin electrode. Experimental current density transients (j-t) were obtained for three different potentiometric behaviors: anionic, cationic, and a combination. Theoretical models were used to fit the experimental j-t data to determine the nucleation and growth processes controlling the polymer synthesis. It was encountered that, in all cases, pyrrole electropolimerization involves two concomitant processes, namely, a Ppy diffusion limited multiple 3D nucleation and growth and pyrrole electro-oxidation on the growing surface of the Ppy nuclei. SEM analysis of the electrodes surfaces reveals that Ppy deposition occurred over most of the electrode surface by multiple nucleation of hemispheres, as the theoretical model used for the analysis of the current transients required. Hemispherical particles formed the polymeric film displaying different sizes. The order for the particle size was as follows: anionic > anionic-cationic > cationic. These results are congruent with those obtained by theoretical analysis of the corresponding current transients. Analysis of the impedance measurements recorded on the anionic Ppy film, immersed in an aqueous solution with different sulfate ion concentrations evidenced that SO(4)(2-) ions diffuse through the Ppy film provoking a decrease of its electrical resistance and an increase of its dielectric constant. From the Warburg impedance coefficient, the sulfate coefficient of diffusion in the Ppy film was 1.38 x 10(-9) cm(2) s(-1).

Simultaneous determination of tetracyclines in poultry muscle by capillary zone electrophoresis.

A capillary zone electrophoresis method with UV detection was developed for the simultaneous detection and quantification of three tetracyclines in chicken meat samples: tetracycline (TC), oxytetracycline (OTC) and doxycycline (DOC). The separation conditions were: a running buffer containing 30 mM sodium phosphate, 2mM EDTA disodium salt and 2.5% 2-propanol, pH 12.0, a 5s hydrodynamic injection and a 14kV separation voltage. Two different clean-up methodologies were employed: solid-phase extraction with C(18) cartridges and ion exchange with Amberlite XAD7 resin. Analytes were detected at 360 nm in less than 12 min. LODs ranged from 61 microg kg(-1) for OTC to 68 microg kg(-1) for DOC with C(18) cartridges, and 81 microg kg(-1) for DOC to 89 microg kg(-1) for TC with Amberlite XAD7 resin. The recoveries for TC, OTC and DOC obtained by both methods were between 85 and 95%, and the peak area repeatability for all of the samples was below 5% in all cases. Twenty-four samples of commercial chicken drumsticks were examined with both clean-up methodologies. In nine cases (37.5%) TC was detected, in a range from 197.8 to 2564.3 microg kg(-1), and in seven cases (29.2%) OTC was detected in a range from 83.0 to 2049.3 microg kg(-1). DOC was not detected in any of the tested samples. This method would be useful for the routine monitoring of TCs residues in poultry muscle.