Raised intensity phonation compromises vocal fold epithelial barrier integrity.

Objectives/hypothesis: We investigated the hypothesis that 30 minutes of raised intensity phonation alters transcript levels of vocal fold intercellular tight junction proteins and disrupts the vocal fold epithelial barrier.

Study Design: Prospective animal study.

Methods: Eighteen New Zealand white breeder rabbits were randomly assigned to receive 30 minutes of raised intensity phonation or approximation of the vocal folds without phonation.

Effects of raised-intensity phonation on inflammatory mediator gene expression in normal rabbit vocal fold.

Objective: To investigate the hypothesis that a transient episode of raised-intensity phonation causes a significant increase in vocal fold inflammatory messenger RNA (mRNA) expression in vivo.

Study Design: Prospective animal study.

Setting: Laboratory.

Age-associated changes in the expression and deposition of vocal fold collagen and hyaluronan.

Objectives: We investigated age-associated changes in the expression and deposition of collagen and hyaluronan (hyaluronic acid; HA) in aged vocal folds.

Methods: Thirty Sprague-Dawley rats were involved in this study. For gene expression analyses, 15 animals were divided into 3 age groups of young (2 month), adult (9 month), and elderly (18 month) rats.

Regenerative effects of basic fibroblast growth factor on extracellular matrix production in aged rat vocal folds.

Objectives: We investigated acute changes in extracellular matrix (ECM) gene expression and histologic changes in the deposition of collagen and hyaluronan (hyaluronic acid; HA) after basic fibroblast growth factor (bFGF) treatment of the aged rat vocal fold.

Methods: For the polymerase chain reaction (PCR) experiments, we divided ten 18-month-old Sprague-Dawley rats into two groups that received serial injections of sham (saline solution) or bFGF (2 ng/microL) and euthanized them 2 weeks after the initial injection to investigate acute changes in ECM gene expression. We treated a separate group of 5 animals unilaterally and sacrificed them 4 weeks after the initial injection to investigate histologic changes in the deposition of collagen and HA.

Regeneration of aged rat vocal folds using hepatocyte growth factor therapy.

Objectives/hypothesis: We investigated acute changes in extracellular matrix gene expression and histologic changes in the deposition of collagen and hyaluronan (HA) from hepatocyte growth factor (HGF) treatment of the aged rat vocal fold. We hypothesized that: 1) HGF induces matrix metalloproteinase gene expression, which might contribute to the downregulation of collagen; and 2) HGF induces hyaluronan synthase (HAS) gene expression, which might play a role in the upregulation of extracellular matrix HA.

Study Design: Prospective animal study.

Characterization of raised phonation in an evoked rabbit phonation model.

Objectives/hypothesis: Our laboratory has developed an in vivo rabbit model to investigate the effects of phonation on expression and turnover of the vocal fold extracellular matrix. As a logical outgrowth of this research to include phonotrauma in the present study, we investigated the hypothesis that an increase in airflow rate delivered to the glottis produces a change in glottal configuration and an increase in mean phonation intensity.

Study Design: Prospective animal study.

Extracellular matrix gene expression during wound healing of the injured rat vocal fold.

Objectives: To measure the expression of procollagen-I and -III, decorin, and hyaluronan synthase (HAS)-1, -2, and -3 during the inflammatory, proliferative, and remodeling phases of rat vocal fold injury.

Study Design: Prospective, animal model.

Subjects And Methods: Vocal folds were injured in 30 rats.

Model of evoked rabbit phonation.

Objectives: We describe a method for eliciting phonation in an in vivo rabbit preparation using low-frequency, bipolar pulsed stimulation of the cricothyroid muscles with airflow delivered to the glottis.

Methods: Ten New Zealand White breeder rabbits weighing 3 to 5 kg were used in this study. The cricothyroid muscles were isolated bilaterally, and separate pairs of anode-cathode hooked-wire electrodes were inserted into each muscle.

Gene expression of transforming growth factor-beta1 and hepatocyte growth factor during wound healing of injured rat vocal fold.

Objectives/hypothesis: To investigate the expression of genes coding transforming growth factor (TGF)-beta1, hepatocyte growth factor (HGF), and c-Met, its membrane-spanning tyrosine kinase receptor, during the inflammatory, proliferative, and remodeling phases of wound healing in the injured rat vocal fold.

Study Design: Prospective animal study.

Methods: Thirty five rats were involved in this study.

Effect of hepatocyte growth factor on gene expression of extracellular matrix during wound healing of the injured rat vocal fold.

Objectives: We performed a prospective, sham-controlled animal study to investigate the effects of hepatocyte growth factor (HGF) manipulation of the extracellular matrix on vocal fold gene expression during acute injury.

Methods: Bilateral vocal fold wounds were created in 40 rats. The rats were randomly assigned to 1 of 2 groups (sham treatment or HGF treatment) and received treatment of the injured area at the time of wounding and on alternate posttreatment days.

Extracellular matrix gene expression after vocal fold injury in a rabbit model.

Objectives: We determined the expression of matrix metalloproteinase (MMP)-1, MMP-9, collagen types I and III, and fibronectin from rabbit vocal folds after injury.

Methods: Thirty rabbits were involved in this study. Five animals were assigned to each time period.

Experimentally induced phonation increases matrix metalloproteinase-1 gene expression in normal rabbit vocal fold.

Objectives: An in vivo rabbit model was used to study the effect of 3 hours of experimentally induced phonation on messenger RNA expression of the normal vocal fold.

Study Design: Prospective; animal model.

Subjects And Methods: Ten rabbits received experimental phonation for 3 hours, followed by 1 hour of recovery.