Straw phonation has a long history of being a successful vocal therapy technique. However, not much is known about the mechanics of phonation with a straw, nor the best combination of phoneme and straw dimensions to be used. A significant limitation in research thus far is the complexity of existing models and computation techniques to determine acoustic and aerodynamic values such as impedance. In this study, a new electrical circuit-based model of the vocal tract as a transmission line is evaluated and compared to established impedance calculation methods. Results indicate that the model is not complete yet, so several adjustments are suggested and discussed. In addition, straw phonation configurations are examined using previously developed models to determine which maximize impedance and power.

Objective. Photodynamic therapy (PDT) is a minimally invasive method with strong tissue selectivity and nonthermal effects. We aim to investigate the efficacy of an in-office method utilizing PDT with local application of 5-aminolevulinic acid (ALA) and 635 nm diode laser for treating laryngeal leukoplakia.Study Design. Retrospective cohort study.Setting. Outpatient clinic-tertiary medical center.Methods. This study reviewed 32 patients with laryngeal leukoplakia, including 11 recurrent cases after surgery. All the procedures were performed in an office setting under topical anesthesia. Fifteen percent ALA solution was locally applied to the lesion through a flexible laryngoscope. Light illumination was performed using a 635 nm diode laser through a 400 μm optic fiber. The power density was 165 mW/cm 2 to reach 100 J/cm 2 . Results of laryngostroboscopy and voice evaluation during follow-up were collected.Results. The mean follow-up was 7.91 ± 4.83 (3-18) months. Thirty-nine procedures were performed, including 1 session for 27 patients, 2 sessions for 3 patients, and 3 sessions for 2 patients. The total response rate was 96.875% (31/32), including complete responses in 26 (81.25%) patients, partial responses in 5 patients (15.625%), and no response in 1 patient (3.125%). It appeared that PDT selectively eliminated the leukoplakia without affecting lamina propria and the surrounding normal mucosa remained unharmed. Scores of Voice Handicap Index-10, jitter, shimmer, and harmonic-tonoise ratio were significantly improved after PDT. Conclusion.Office-based PDT is an effective, repeatable, and practical method for treating laryngeal leukoplakia. Local application of ALA is sufficient to achieve photodynamic reactions. PDT could eliminate laryngeal leukoplakia selectively while protecting the normal laryngeal structure.

Purpose In this study, we aim to systematically evaluate the damaging role of gastric (pepsin and acid) and duodenal ingredients (bile acids) on vocal fold epithelium in excised porcine larynges. Methods Fresh ex vivo porcine larynges were exposed to one of five experimental conditions for 1 h. These conditions will be referred to as alkaline deoxycholic acid, acidic pepsin, acid pH3 only, acid pH5 only, and control, respectively. A Franz diffusing cell was used to evaluate the barrier function of vocal fold epithelium by measuring the permeability to fluorescein isothiocyanate dextran of 4 kDa. Histological changes were observed using transmission electron microscopy. Results After immersing the fresh porcine larynges in the five solution groups, we found that the vocal fold epithelium in the deoxycholic acid group had more permeability to FD4 than the pepsin group (P < 0.001). Fragmentation and desquamation of dead cell layers were observed in both the pepsin and deoxycholic acid groups, but were more severe in the deoxycholic acid group than the pepsin group. The thickness of the dead epithelial cell layer gradually increased with increasing acid concentration (P < 0.05). Additionally, the thickness of the dead epithelial cell layer in the deoxycholic acid group was significantly higher than that in the pepsin group (P < 0.01). Conclusion Deoxycholic acid in a weakly acidic condition is more likely than pepsin to induce apoptosis in ex vivo porcine vocal fold epithelium, destroy the link proteins between epithelial cells, and affect their integrity and barrier function. Keywords Vocal fold • Laryngopharyngeal reflux • Barrier function • Integrity • PermeabilityZhewei Lou and Ting Gong have contributed to the work equally and should be regarded as co-first authors.

Objective: Studies showed that photodynamic therapy (PDT) might be able to prevent vocal fold scar formation when treating laryngeal lesions. We aim to investigate if PDT improves vocal wound healing and reduces scar formation in both prophylactic and remodeling procedures performed in vivo.Study Design: In vivo. Methods: Vocal fold stripping was performed in Sprague-Dawley rats. PDT was performed with intraperitoneal injection of 100 mg/kg 5-Aminolevulinic Acid (5-ALA) and 635 nm laser irradiation of 20, 40, and 60 J/cm 2 . PDT was performed immediately after surgery to study the prophylactic effect and 4 weeks after surgery to study the remodeling effect. Gene expression was evaluated with real-time PCR at 1 week after PDT. Histologic evaluations were performed 12 weeks after PDT, including hematoxylin-eosin, Masson, Alcian blue staining, and immunohistochemical staining of collagen I and III.Results: PDT induced similar effects on the vocal fold wound healing outcomes in both prophylactic and remodeling procedures. Expression of MMP8, MMP13, HAS2, and TGFβ1 was significantly elevated. Histologic evaluation revealed significantly increased thickness, decreased density of collagen, and increased deposition of hyaluronic acid in the lamina propria. Immunohistochemistry also revealed better distribution and reduced density of collagen I and III. The most obvious changes were seen in the 60 J/cm 2 PDT group.Conclusion: PDT could significantly improve vocal wound healing by providing both prophylactic effects and remodeling effects. It may be a minimally invasive treatment for vocal fold lesions with slight vocal scarring, and may be used to treat acute or chronic vocal injury to reduce vocal scarring.

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