Traumatic vocal fold avulsion injury in a newborn

A full-term newborn developed respiratory compromise in the immediate postparturition period requiring urgent intubation. Evaluation of post-extubation stridor later the same day revealed an avulsion injury extending from the left vocal fold into the lateral glottic musculature. Primary repair was accomplished with anatomic realignment of the torn vocal fold and muscle. Endotracheal intubation was utilized for stenting and the patient was extubated following 3 days of paralysis with sedation. Follow-up examination revealed a reparative granuloma, which was lasered. Eight-week follow-up examination revealed normal vocal fold architecture. At 18 months the patient continues to have a normal voice and normal laryngeal development.     

Liquid chromatography coupled to on-line post column derivatization for the determination of organic compounds: A review on instrumentation and chemistries

Analytical derivatization either in pre or post column modes is one of the most widely used sample pretreatment techniques coupled to liquid chromatography. In the present review article we selected to discuss the post column derivatization mode for the analysis of organic compounds. The first part of the review focuses to the instrumentation of post-column setups including not only fundamental components such as pumps and reactors but also less common parts such as static mixers and back-pressure regulators; the second part of the article discusses the most popular “chemistries” that are involved in post column applications, including reagent-less approaches and new sensing platforms such as the popular gold nanoparticles. Some representative recent applications are also presented as tables.     

Triple quantum nutation in the two-level NMR system in the rotating frame

The authors present the detailed theory and the new results associated with the triple quantum (TQ) nutation and the line narrowing effect of the TQ resonance in the two-level NMR system which we reported previously. The TQ resonance is induced in the spin-locked system by the oscillating field produced by the sinusoidal phase modulation (PM) of the RF field. The theory predicts that the TQ nutation is accompanied by several higher frequency oscillations and we detected them experimentally by improving the detection system. These higher frequency oscillations are due to the fluctuation of the angle between the transverse or effective field causing the TQ nutation and the RF field. We obtain the result that the modulation index 2phim of the PM is the key parameter that essentially controls the conditions of the TQ resonance and the narrowing effect. Under the exact TQ resonance, the ratio of the TQ resonance frequency to the Larmor frequency of the RF field depends only on phim, and the secular part of the magnetic dipole Hamiltonian of a like spin system in the triply rotating frame disappears at a particular value of phim. The condition is different from that of the well-known magic angle condition.     

The treatment of vocal fold paralysis with injectable collagen: Clinical concerns

Over the past several years, the treatment of vocal cord paralysis has been substantially improved by the availability of injectable Teflon. This substance, suspended in glycerin, has provided consistent results in laryngeal rehabilitation due to its tissue tolerance and lack of resorption. Recently, moified bovine collagen has been proposed as an additional substance for use in vocal cord injections to treat vocal fold paralysis. Collagen is currently being used for augmentation of dermatologic scarring, especially on the face. It has undergone clinical trials and has now been approved for clinical use in this setting. Bovine collagen has proven very useful in scar modification. The injections are generally well tolerated and adverse responses do not often occur. Most of the adverse local reactions can be avoided by using a skin test on the forearm 1 month prior to treatment and excluding those patients with positive responses.     

Structure, Stability, and Activity of Adsorbed Enzymes

A proteolytic enzyme, α-chymotrypsin, and a lipolytic enzyme, cutinase, were adsorbed from aqueous solution onto a hydrophobic Teflon surface and a hydrophilic silica surface. We investigated the influence of adsorption on the structure, the structure thermal stability and the activity of these enzymes. Probing the protein structure by circular dichroism spectroscopy indicates that Teflon promotes the formation of helical structure in α-chymotrypsin, but the reverse effect is found with cutinase. The perturbed protein structures on Teflon are remarkably stable, showing no heat-induced structural transitions up to 100°C, as monitored by differential scanning calorimetry. Contact with the hydrophilic silica surface leads to a loss in the helix content of both proteins. Differential scanning calorimetry points to a heterogeneous population of adsorbed protein molecules with respect to their conformational states. The fraction of the native-like conformation in the adsorbed layer increases with increasing coverage of the silica surface by the proteins. The specific enzymatic activity in the adsorbed state qualitatively correlates with the fraction of proteins in the native-like conformation.     

Force measurements between Teflon AF and colloidal silica particles in electrolyte solutions

The interaction force between a very hydrophobic polymer surface and colloidal silica particles with a roughness of 10–15 nm has been measured in aqueous solutions of KOH and KCl using an atomic force microscope. The interaction can be described according to the DLVO theory by an electrical double-layer force that is repulsive at long distances and attractive at short distances and an attractive van der Waals force. The electrical double-layer potentials are compared to the zeta potentials of Teflon AF and the silica spheres. The roughness of the silica particles leads to an underestimation of the short-range attraction and the surface potential. Both KCl and KOH solutions affect the potential of the interacting surfaces. OH⁻ ions that adsorb preferentially to the Teflon AF surface create higher potentials than Cl⁻ ions. Range and strength of the attractive interaction are not affected by KCl solutions but reduced by addition of KOH. This can be explained by decreasing potential differences between the silica sphere and Teflon AF with increasing KOH concentration. In addition, the preferential adsorption of OH⁻ ions may lead to a reduction of the van der Waals interaction. The presence of nanobubbles, too, might play a role.     

Treatment of laryngeal contact ulcers and granulomas: A 12-year retrospective analysis

Multiple etiological factors including gastroesophageal reflux, hyperfunctional voice use, and endotracheal intubation have been implicated in the development of posterior laryngeal ulcers and granulomas. The optimal approach to treatment of these lesions remains controversial. The mainstay of treatment at Vancouver General Hospital has been aggressive medical management of gastroesophageal reflux, with complimentary voice therapy offered to patients suspected of having significant hyperfunctional phonation. The authors reserve Botulinum toxin injection or surgical excision for patients who fail initial therapy. They conducted a retrospective analysis of their voice clinic records from 1985–1997 to examine the efficacy of this approach. They identified 76 patients with the diagnosis of contact ulcer or granuloma. Fifty-two patients had follow-up data available for review. Ninety-four percent of patients were treated nonsurgically: 35 patients were treated solely by dietary and medical therapy to control gastroesphageal reflux, 10 patients were treated by a combination of medical gastroesophageal reflux control and voice therapy, 3 patients had Botox injections, 2 patients had surgical excision of granuloma, 1 patient had a Kenalog injection, and 1 patient underwent laparoscopic fundoplication. Overall, 77% of patients had complete resolution, whereas 11% had partial resolution and another 11% had no significant improvement. The data supports control of gastroesophageal reflux as a central component in treatment of posterior laryngeal ulcers and granulomas.     

A new quantitative Raman measurement scheme using Teflon as a novel intensity correction standard as well as the sample container

A novel and reliable quantitative Raman measurement scheme has been proposed for the analyses of ethanol and isopropanol solutions. Teflon tubing was employed as an effective intensity correction standard as well as the sample cell. This allowed for the synchronous collection of the mixed Raman spectrum from the Teflon standard and the sample without any extra optical configuration. A non‐overlapping Teflon band was used as the standard peak to correct the Raman intensity changes resulting from laser power variations. In addition to the use of Teflon tubing,a wide area illumination (WAI) scheme was employed, which made the laser illumination into a circle of 6 mm diameter (area: 28.7 mm²), to cover a wide sample area. The WAI scheme improved the reliability of the Raman measurement by significantly increasing the reproducibility of the sampling owing to a decreased sensitivity to sample placement with respect to the focal plane as well as a wider sample coverage area. The resulting Raman spectra were more reproducible and more representative of the correct sample composition. Overall, a superior prediction performance was achieved using the WAI scheme compared to the conventional Raman collection method. The proposed system has great potential for use in the quantitative analysis of diverse liquid samples with good reproducibility. Copyright © 2006 John Wiley & Sons, Ltd.     

Teflon hierarchical nanopillars with dry and wet adhesive properties

The superior material properties of β‐keratin along with the hierarchical high‐aspect‐ratio structure of geckos' foot pad have enabled geckos to stick readily and rapidly to almost any surfaces in both dry and wet conditions. In this research, nonsticky fluoropolymer (Teflon AF) resembling β‐keratin rigidity and having an extremely low surface energy and dielectric constant was applied to fabricate a novel dry adhesive consisting of high‐aspect‐ratio nanopillars terminated with a “fluffy” top layer. Both the nanopillars and the terminating layer are fabricated concurrently by replica molding using a nanoporous anodic aluminum oxide membrane as the mold. These Teflon AF hierarchical nanostructures are shown to have an exceptional capacity to generate strong adhesion in both dry conditions and under water because of combined actions of van der Waals forces, electrostatic attractions, and hydrophobic effects. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Fluorometric Characteristics of a Wave‐Guide Cell with Low Refractive Index

Recently, Teflon AF2400 (AF 1600, and AF 1601) was commercialized (DuPont Fluoroproducts, Wilmington, DE, U.S.A), that has a refractive index (1.29) lower than water (1.33), and which means that the wave‐guiding of light is possible in water. In this study, we used Teflon AF 2400 as a waveguide capillary longpath cell for fluorometry. He‐Cd and Ar⁺ lasers were used as the excitation source, at 325 nm and 514.5 nm respectively. The length of the capillary wave‐guide cell was 18.70 cm. The was wound twice on a flat surface (loop diameters: 2 cm and 3 cm). The excitation was executed through the wave‐guide cell and the fluorescence from the wound capillary cell wall was collected in a perpendicular direction to the loop. With excitation at 325 nm, the fluorescence intensity at 450 nm emitted from the cell wall decreased along with the increase in the refractive index of the solvent. This can be caused by attenuation of the source light due to absorption by the solvent. In our experiment, the solvent of higher refractive index has the higher absorption at 325 nm. On the other hand, the fluorescence intensity at 590 nm, with excitation at 514.5 nm, increases with increased refractive index of the solvent. This result shows that an increase in the refractive index of the solvent is preferable for maintaining the wave‐guiding of the source light. Here, the characteristics of fluorescence spectrometry are discussed in terms of the collection of fluorescence from the wave‐guide capillary cell wall.