Polyethylenimine Functionalized with Dopamine: Characterization and Electrocatalytic Properties

We report the chemical modification of polyethylenimine (PEI) by functionalization with dopamine (Do) using glutaraldehyde (Glu) as a linker (PEI‐Glu‐Do). The new polymer was characterized by FT‐IR spectroscopy, by derivative UV‐vis spectroscopy, and Cyclic Voltammetry. The PEI‐Glu‐Do demonstrated to have an important electrocatalytic activity allowing an important decrease in the overvoltages for the oxidation of NADH and a significant increase in its oxidation peaks currents. Different ratios of PEI:Do were assayed and the best response was obtained using PEI : Glu : Do 1 : 2 : 1. The new polymer represents an interesting and promising alternative for the electrochemical quantification of NADH and other analytes of clinical interest, as well as for the development of new electrochemical (bio)sensors.     

Glassy Carbon Electrodes Modified with Multiwall Carbon Nanotubes Dispersed in Polylysine

We report the analytical performance of glassy carbon electrodes (GCE) modified with a dispersion of multiwall carbon nanotubes (MWCNT) in polylysine (Plys) (GCE/MWCNT‐Plys). The resulting electrodes show an excellent electrocatalytic activity towards different bioanalytes like ascorbic acid, uric acid and hydrogen peroxide, with important decrease in their oxidation overvoltages. The dispersion of 1.0 mg/mL MWCNT in 1.0 mg/mL polylysine is highly stable, since after 2 weeks the sensitivity for hydrogen peroxide at GCE modified with this dispersion remained in a 90% of the original value. The MWCNT‐Plys layer immobilized on glassy carbon electrodes has been also used as a platform to build supramolecular architectures by self‐assembling of polyelectrolytes based on the polycationic nature of the polylysine used to disperse the nanotubes. The self‐assembling of glucose oxidase has allowed us to obtain a supramolecular multistructure for glucose biosensing. The influence of glucose oxidase concentration and adsorption time as well as the effect of using polylysine or MWCNT‐Plys as polycationic layers for further adsorption of GOx is also evaluated.     

Carbon nanotubes for electrochemical biosensing

The aim of this review is to summarize the most relevant contributions in the development of electrochemical (bio)sensors based on carbon nanotubes in the last years.Since the first application of carbon nanotubes in the preparation of an electrochemical sensor, an increasing number of publications involving carbon nanotubes-based sensors have been reported, demonstrating that the particular structure of carbon nanotubes and their unique properties make them a very attractive material for the design of electrochemical biosensors.The advantages of carbon nanotubes to promote different electron transfer reactions, in special those related to biomolecules; the different strategies for constructing carbon nanotubes-based electrochemical sensors, their analytical performance and future prospects are discussed in this article.     

Validity and Reliability of the Reflux Symptom Index (RSI)

Laryngopharyngeal reflux (LPR) is present in up to 50% of patients with voice disorders. Currently, there is no validated instrument that documents symptom severity in LPR. We developed the reflux symptom index (RSI), a self-administered nine-item outcomes instrument for LPR. The purpose of this investigation was to evaluate the psychometric properties of the RSI. For validity assessment, 25 patients with LPR were evaluated prospectively before and six months after b.i.d. treatment with proton pump inhibitors (PPI). Each patient completed the RSI as well as the 30-item voice handicap index (VHI). For reliability assessment, the study patients were given the RSI on two separate occasions before the initiation of treatment. Normative RSI data were derived from 25 age-matched and gender-matched controls taken from an existing database of asymptomatic individuals without any evidence of LPR. The mean RSI (+/- standard deviation) of patients with LPR improved from 21.2 (+/- 10.7) to 12.8 (+/- 10.0), and the mean VHI improved from 52.2 (+/- 24.7) to 41.5 (+/- 25.0) after 6 months of therapy (p = 0.001 and 0.065, respectively). Of the three VHI subscales (emotional, physical, functional), only the functional subscale improved significantly (p = 0.037). Patients who experienced a five point or better improvement in RSI were 11 times more likely to experience a five-point improvement in VHI (95% confidence interval = 1.7, 76.8). For reliability assessment, the first and second pretreatment RSIs were 19.9 (+/- 11.1) and 20.9 (+/- 9.6), respectively (correlation coefficient = 0.81, p < 0.001). The single-item correlation coefficients ranged from 0.41 to 0.91 (p < 0.05 for all items). The mean pretreatment RSI in patients with LPR was significantly higher than controls (21.2 versus 11.6; p < 0.001). The mean RSI of patients with LPR after 6 months of PPI therapy approached that of asymptomatic controls (p > 0.05). The RSI is easily administered, highly reproducible, and exhibits excellent construct and criterion-based validity.     

Fibronectin: An Interesting Vocal Fold Protein

A great deal of information is accruing regarding the function of the extracellular matrix. Once thought to be simply a structural entity to surround cells, it is now known to do much more. Fibronectin in particular has received specific attention. Fibronectin is a ubiquitous glycoprotein found most abundantly in the extracellular matrix of regenerating, healing, and embryonic tissue. Vast evidence supports the fact that fibronectin participates in many diverse functions throughout the body that are relevant to vocal fold biology. This article introduces the structure of fibronectin and its isoforms and provides an introduction to some of the many functions it plays. It also reviews the evidence about fibronectin's place in vocal folds and vocal fold pathology. It discusses fibronectin's presence in vocal nodules, vocal polyps, vocal scarring, and Reinke's edema, and reviews the data on its role in mucosal wave impairment. Lastly, it discusses preliminary microarray data that show gene expression for fibronectin to be upregulated in true vocal folds when compared to false vocal folds.     

Short-Term Therapeutic Trial of Proton Pump Inhibitors in Suspected Extraesophageal Reflux

Pharyngoesophageal gastric acid reflux is thought to initiate chronic posterior laryngitis. The gold standard for measuring gastric reflux is dual-channel 24-hour pH monitoring. This is a time-consuming, inconvenient, expensive method that is not available in all areas. New therapeutic regimes that make use of proton pump inhibitors (PPIs) have proven to be therapeutically efficient for control of acid reflux. Twenty-four consecutive patients with chronic voice disorders and signs of posterior laryngitis were selected for therapy. Twenty-four hour pH monitoring was performed independently before the therapy. The trial therapy consisted of all patients receiving pantoprazole, 40 mg once daily for 6 weeks. Immediately following the therapy a statistically significant (p < 0.05) improvement was observed in all patients. This improvement was analyzed retrospectively by comparison with the results of 24-hour pH monitoring. In 71% of the patients the 24-hour pH-monitoring gave a positive result showing a high number of patients with extraesophageal reflux in our study group. Patients with positive results of pH-monitoring responded in a statistically significant manner (p < 0.05) to the pantoprazole therapy, whereas those patients without detected reflux did not. A 3-month follow-up of the patients with a positive result of the pH-monitoring confirmed the improvement. No patients reported adverse effects. A 6-week treatment with pantoprazole can be clinically justified. It helps to save time and reduce costs, allows for selection of reflux-negative patients for alternative therapy, and may prevent inadequate treatment of patients with false-negative pH monitoring. Twenty-four hour pH monitoring is still recommended for patients unresponsive to this trial therapy.     

Electrophysiologic monitoring of the recurrent laryngeal nerves may not predict bilateral vocal fold immobility after thyroid surgery

Two cases of bilateral vocal fold immobility (VFI) after identification and preservation of the recurrent laryngeal nerves (RLNs) required tracheotomy until vocal fold recovery. The first patient underwent thyroid surgery without preoperative or postoperative evaluation of the vocal folds, administration of postoperative intravenous steroids, or electrophysiologic monitoring of the RLNs, whereas the second patient underwent a thyroid procedure in which all of the aforementioned were executed. Preoperative and postoperative clinical evaluation of the RLNs is strongly suggested in patients undergoing thyroid surgery, especially revision surgery. Patients potentially undergoing total thyroidectomy should be counseled about the remote chance of airway obstruction and should be properly selected for this operation. Subclinical stretching of the RLNs or ischemia from the endotracheal tube cuff can result in unilateral VFI, and rarely bilateral VFI, requiring reintubation, tracheotomy, or vocal fold lateralization. Electrophysiologic monitoring may not always predict bilateral VFI.     

Highly Sensitive and Selective Glucose Biosensing at Carbon Paste Electrodes Modified with Electrogenerated Magnetite Nanoparticles and Glucose Oxidase

This work reports the advantages of carbon paste electrodes modified with electrogenerated magnetite nanoparticles. The nanoparticles present catalytic activity towards hydrogen peroxide reduction. The incorporation of glucose oxidase (GOx) and magnetite in a carbon paste matrix have made possible the development of an efficient glucose biosensor. The effect of the amount of GOx and magnetite present in the composite on the response of the biosensor was critically evaluated. The biosensors demonstrated to be highly selective, with negligible interference of ascorbic acid and uric acid. The proposed biosensor was challenged with human blood serum demonstrating an excellent correlation with the spectrophotometric method.     

Stability and convergence of the spectral Lagrange-Galerkin method for mixed periodic/non-periodic convection-dominated diffusion problems

We present a convergence analysis of the spectral Lagrange-Galerkinmethod for mixed periodic/non-periodic convection-diffusionproblems. The scheme is unconditionally stable, independentof the diffusion coefficient, even in the case when numericalquadrature is used. The theoretical predictions are illustratedby a series of numerical experiments. For the periodic case,our results present a significant improvement on those givenby Süli & Ware (1991) SIAM J. Numer.Anal.28, 423-445).     

Tests of significance using selected sample quantiles

Large sample tests of significance for the location parameter, the scale parameter, and quantiles for a location-scale family of distributions based on a few optimally chosen sample quantiles are considered.