Inspiratory pressure threshold training for upper airway limitation: a case of bilateral abductor vocal fold paralysis

A single subject design was used to determine if pressure threshold training strengthens the inspiratory muscles in a subject with a limited glottal airway as well as diminish dyspnea and improve parameters of speech. The subject was a 19-year-old woman whose glottal airway was limited due to bilateral abductor vocal fold paralysis following a thyroidectomy. A 5-week inspiratory muscle strength-training program was implemented using a pressure-threshold trainer to strengthen the inspiratory muscles with the intent of enabling the generation of higher inspiratory pressures. The pressure threshold on the trainer was set at 75% of the subject's maximum inspiratory pressure (MIP). The subject was required to generate sufficient inspiratory pressure to bring air through the trainer during an inspiratory maneuver. MIP was the dependent variable used as an indication of inspiratory muscle strength. MIP increased by 47% following the training program. Maximal minute ventilation and oxygen uptake increased posttraining. Dyspnea during exercise and speech decreased as reported by the subject. Total reading duration and pause duration demonstrated a declining trend during connected speech. The results indicated that inspiratory muscle training using a pressure threshold device improves functional tasks such as exercise and speech in a subject with upper airway limitation.     

Unilateral cricothyroid contraction and glottic configuration

It is frequently stated that unilateral cricothyroid muscle (CT) paralysis can be diagnosed by physical examination, noting rotation of the glottis, and shortening and vertical displacement of the ipsilateral vocal fold. These signs, however, are inconsistently observed, and there is considerable controversy regarding the direction of glottic rotation. To determine the effects of CT contraction on three-dimensional glottic configuration, we performed computerized tomography on cadaver larynges before and after simulated CT contraction. Radiopaque makers were used to compute distances. Unilateral CT contraction equally increased the length of both membranous vocal folds, and rotated the posterior glottis less than 1 mm. CT contraction neither adducted the vocal processes, nor significantly their altered vertical level. These results suggest that unilateral CT paralysis cannot be diagnosed on the basis of any clinically apparent change in glottal configuration.     

Kinetic partitioning mechanism as a unifying theme in the folding of biomolecules

We describe a unified approach to describe the kinetics of protein and RNA folding. The underlying conceptual basis for this framework relies on the notion that biomolecules are topologically frustrated due to their polymeric nature and due to the presence of conflicting energies. As a result, the free energy surface (FES) has, in addition to the native basin of attraction (NBA), several competing basins of attraction. A rough FES results in direct and indirect pathways to the NBA, i.e., a kinetic partitioning mechanism (KPM). The KPM leads to a foldability principle according to which fast folding sequences are characterized by the folding transition temperature T _F being close to the collapse transition temperature T _θ, at which a transition from the random coil to the compact structure takes place. Biomolecules with T _θ ≈ T _F , such as small proteins and tRNAs, are expected to fold rapidly with two-state kinetics. Estimates for the multiple time scales in KPM are also given. We show that experiments on proteins and RNA can be understood semi-quantitatively in terms of the KPM. Received: 14 January 1997 / Accepted: 23 January 1997     

Migration of the anterior segment following anterior commissure advancement: A case report

A 53-year-old man with severe vocal fold atrophy underwent bilateral type 1 thyroplasty and anterior commissure advancement. Postoperatively, he developed a strained voice with less projection and volume than prior to surgery. This was verified by objective assessment of vocal function. Videoendoscopy revealed bilateral false vocal fold fullness and blunting of the anterior commissure. Magnetic resonance imaging demonstrated cephalic migration of the posterior ends of the implants and retrusion of the anterior commissure segment. Surgical exploration revealed that the type 1 implants had rotated and buckled. The anterior commissure segment was rotated and displaced inferiorly, and its inferior surface was tethered to the cricoid by scar tissue. The implants were removed, the anterior segment was repositioned and rigidly fixed, and bilateral lipoinjection performed. Vocal function was significantly improved, and endoscopy revealed normal tension and length of the vocal folds and restoration of the anterior commissure. This case demonstrates the importance of stable fixation during laryngeal framework surgery     

Identification of N‐glycans from Ebola virus glycoproteins by matrix‐assisted laser desorption/ionisation time‐of‐flight and negative ion electrospray tandem mass spectrometry

The larger fragment of the transmembrane glycoprotein (GP1) and the soluble glycoprotein (sGP) of Ebola virus were expressed in human embryonic kidney cells and the secreted products were purified from the supernatant for carbohydrate analysis. The N‐glycans were released with PNGase F from within sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS‐PAGE) gels. Identification of the glycans was made with normal‐phase high‐performance liquid chromatography (HPLC), matrix‐assisted laser desorption/ionisation mass spectrometry, negative ion electrospray ionisation fragmentation mass spectrometry and exoglycosidase digestion. Most glycans were complex bi‐, tri‐ and tetra‐antennary compounds with reduced amounts of galactose. No bisected compounds were detected. Triantennary glycans were branched on the 6‐antenna; fucose was attached to the core GlcNAc residue. Sialylated glycans were present on sGP but were largely absent from GP1, the larger fragment of the transmembrane glycoprotein. Consistent with this was the generally higher level of processing of carbohydrates found on sGP as evidenced by a higher percentage of galactose and lower levels of high‐mannose glycans than were found on GP1. These results confirm and expand previous findings on partial characterisation of the Ebola virus transmembrane glycoprotein. They represent the first detailed data on carbohydrate structures of the Ebola virus sGP. Copyright © 2010 John Wiley & Sons, Ltd.     

Fast low-angle positive contrast steady-state free precession imaging of USPIO-labeled macrophages: theory and in vitro experiment

The feasibility of imaging macrophages labeled with ultrasmall superparamagnetic iron-oxide nanoparticles (USPIO) with fast low-angle positive contrast steady-state free precession (FLAPS) was investigated through theory and in vitro experiment. Human macrophage cells were labeled with USPIO and imaged at 1.5 T. The metric “visibility,” which combines magnitude and spatial extent of positive contrast, was used to evaluate the images. Negative contrast steady-state free precession (SSFP) and gradient-echo (GRE) imaging were also evaluated. Positive contrast was observed for relatively high concentrations of labeled cells for flip angles less than α=25°. Theoretical and experimental results indicate that positive visibility (VIS_POS) was maximized at α=10° and 15°. Low flip angle SSFP also provided negative contrast comparable to standard SSFP and GRE imaging. Results suggest that USPIO-labeled macrophages are capable of producing the conditions necessary for positive contrast with FLAPS at clinical field strength (1.5 T) and resolution (0.8×0.8×3 mm³).     

Cryopreservation of Arabidopsis thaliana shoot tips

Development of a successful shoot tip cryopreservation method for Arabidopsis thaliana L. will enable researchers to use molecular tools to study processes important for successful cryopreservation in this model organism. We demonstrate that Arabidopsis can be successfully cryopreserved using either plant vitrification solution 2 (PVS2) or plant vitrification solution 3 (PVS3) as cryoprotectants prior to rapidly cooling shoot tips in liquid nitrogen (LN). Shoot tip regrowth after PVS2 cryoprotectant treatment was improved after cold acclimation treatments of 8 or 18 days. All of the shoots tips regrew after LN exposure when cryoprotected with PVS3 for 60 min at 22 degree C. In addition, shoot tips could be cryopreserved using a two-step cooling procedure with PGD (polyethylene glycol-glucose-dimethyl sulfoxide) as a cryoprotectant. The high levels of shoot formation after LN exposure of Arabidopsis shoot tips makes this a desirable system in which molecular tools can be used to examine how alterations in biochemical, metabolic and developmental processes affect regrowth after cryoprotective treatments.