Cyclic strain increases fibroblast proliferation, matrix accumulation, and elastic modulus of fibroblast-seeded polyurethane constructs.

Rapid induction of matrix production and mechanical strengthening is essential to the development of bio-artificial constructs for repair and replacement of load-bearing connective tissues. Toward this end, we describe the development of a mechanical bioreactor and its application to investigate the influence of cyclic strain on fibroblast proliferation, matrix accumulation, and the mechanical properties of fibroblast-seeded polyurethane constructs (FSPC). Human fibroblasts were cultured in 10% serum-containing conditions within three-dimensional, porous elastomeric substrates under static conditions and a model regime of cyclic strain (10% strain, 0.25 Hz, 8 h/day), with and without ascorbic acid supplementation. After one week, the combination of cyclic strain and ascorbic acid resulted in significantly increased construct elastic modulus (>110%) relative to either condition alone. In contrast, cyclic strain alone was sufficient to stimulate significant increases in fibroblast proliferation. Mechanical strengthening of FSPCs was accompanied by increased type I collagen and fibronectin matrix accumulation and distribution, and significantly increased gene expression for type I collagen, TGFbeta-1, and CTGF. These results suggest that strain-induced conditioning in vitro leads to mechanical strengthening of fibroblast/material constructs, most likely resulting from increased collagen matrix deposition, secondary to strain-induced increases in cytokine production.

Crosslinked hyaluronan hydrogels containing mitomycin C reduce postoperative abdominal adhesions.

OBJECTIVE: To evaluate the efficacy of crosslinked hyaluronan (HA) hydrogels that contained covalently-bound mitomycin C (MMC) in reducing postoperative adhesions in a rat uterine horn model. DESIGN: Two independent parameters were investigated: [1] the quantity of MMC in preformed crosslinked hydrogel films and [2] the efficacy of intraperitoneal injection of in situ crosslinkable solutions. SETTING: University animal research facility. ANIMAL(S): Female Wistar rats. INTERVENTION(S): Injuries (3 x 10 mm) were made to contacting serosal surfaces of the medial uterine wall musculature in female rats. Two treatment protocols were used. In the first, sterile crosslinked HA films that contained different MMC loadings (0, 0.5%, and 2%) were applied to two injured uterine horns; control animals received no films. In the second protocol, MMC-loaded crosslinked HA gels that contained different MMC loadings (0.31%, 0.625%, and 1.25%) were spread on the site of uterine horn injury (1 mL); then, an additional 4 mL of the same formulation was injected into the peritoneal cavity after abdominal closure. Control animals were injected with 5 mL of buffer only. MAIN OUTCOME MEASURE(S): Extent of postoperative adhesions between uterine horns and with surrounding tissues and organs. RESULT(S): Mitomycin C-loaded crosslinked HA films and in situ crosslinked gels were more effective in reducing postoperative adhesion formation than were buffer controls or crosslinked HA films without MMC. CONCLUSION(S): Mitomycin C-loaded crosslinked HA films and gels reduced formation of postoperative intraperitoneal adhesions.

Time and dose effects of mitomycin C on extracellular matrix fibroblasts and proteins.

OBJECTIVES/HYPOTHESIS: The objective was to determine treatment dose and time-dependent effects of injected mitomycin C on extracellular matrix fibroblasts, collagen, and fibronectin, important mediators in the wound healing response, in a rat cutaneous wound model. STUDY DESIGN: A prospective, controlled animal study. METHODS: Forty rats were injected with three different doses (0.4, 2.3, and 5.0 mg/mL) of mitomycin C at three different wound sites with a fourth wound site receiving saline as a control. The rats were grouped to have their tissue harvested at five different dates ranging from 1 week to 8 weeks. After death, samples from the wound site underwent Western blot analysis for collagen and fibronectin and histological analysis measuring fibroblast apoptosis. RESULTS: Over an 8-week period, collagen and fibronectin significantly decreased and fibroblast apoptosis significantly increased. No correlation was found between the injected dose of mitomycin C and either the extracellular matrix protein concentration or the rate of fibroblast apoptosis. CONCLUSION: Mitomycin C demonstrated a long-term effect in a wound, inhibiting collagen and fibronectin production and inducing apoptosis. Use of mitomycin C in excess of 0.4 mg/mL did not alter protein concentrations or rate of apoptosis.

Voice disorders in the general population: prevalence, risk factors, and occupational impact.

OBJECTIVES: Epidemiologic studies of the prevalence and risk factors of voice disorders in the general adult population are rare. The purpose of this investigation was to 1) determine the prevalence of voice disorders, 2) identify variables associated with increased risk of voice disorders, and 3) establish the functional impact of voice disorders on the general population. STUDY DESIGN: Cross-sectional telephone survey. METHODS: A random sample (n = 1,326) of adults in Iowa and Utah was interviewed using a questionnaire that addressed three areas related to voice disorders: prevalence, potential risk factors, and occupational consequences/effects. RESULTS: The lifetime prevalence of a voice disorder was 29.9%, with 6.6% of participants reporting a current voice disorder. Stepwise logistic regression identified specific factors that uniquely contributed to increased odds of reporting a chronic voice disorder including sex (women), age (40-59 years), voice use patterns and demands, esophageal reflux, chemical exposures, and frequent cold/sinus infections. However, tobacco or alcohol use did not independently increase the odds of reporting of a chronic voice disorder. Voice disorders adversely impacted job performance and attendance, with 4.3% of participants indicating that their voice had limited or rendered them unable to do certain tasks in their current job. Furthermore, 7.2% of employed respondents reported that they were absent from work 1 or more days in the past year because of their voice, and 2% reported more than 4 days of voice-related absence. CONCLUSIONS: The results of this large epidemiologic study provide valuable information regarding the prevalence of voice disorders, factors that contribute to voice disorder vulnerability, and the functional impact of voice problems on the general population.

Occupational risk factors associated with voice disorders among teachers.

PURPOSE: This study was designed to determine the occupational risk factors associated with voice disorders among schoolteachers, a high-risk population for developing voice problems. METHODS: Telephone interviews were completed by 1243 teachers from Utah and Iowa. Response rates were 98% and 95%, respectively. Bivariate analyses were computed and assessed using chi-square test and Cochran-Mantel-Haenszel test, and logistic regression analyses were performed and resulting odds ratios assessed using 95% confidence intervals. RESULTS: Teachers of vocal music, drama, other performing arts and chemistry were at significantly greater risk of having a voice disorder (OR=2.2, 95% CI: 1.2-4.0; OR=2.1, 95% CI: 0.9-4.8; OR=1.6, 95% CI: 1.0-2.4; OR=2.0, 95% CI: 1.1-3.4), while teachers of special and vocational education had a significantly lower risk (OR=0.5, 95% CI: 0.3-0.7; OR=0.6, 95% CI: 0.4-0.9). When adjusted for the intensity of vocalization, only teachers of chemistry were significantly at risk (OR=2.0, 95% CI: 1.1-3.5) while teachers of special education continued to have less of a risk (OR=0.5, 95% CI: 0.4-0.8). Chronic voice disorders were more prevalent among teachers of vocal music (OR=4.1, 95% CI: 2.2-7.9) and less prevalent among teachers of vocational education (OR=0.29, 95% CI: 0.09-0.95). CONCLUSIONS: These findings suggest that teachers of specific courses are at greater risk of developing a voice disorder.

Comparison of human fibroblast ECM-related gene expression on elastic three-dimensional substrates relative to two-dimensional films of the same material.

Three-dimensional elastic substrates were fabricated from a commercially available polyurethane with an internal porosity of approximately 70% and elastic modulus of 27.4+/-2.76 KPa and examined for suitability in vocal fold tissue engineering. Using immunohistochemistry, biomechanical testing, and RT-PCR; we examined human fibroblast viability, distribution and extracellular matrix related gene expression within substrates for periods up to 4 weeks. We found that cells were capable of colonizing the entire volume of a 5mm wide x 3mm deep x 20mm long substrate at high viability. Histological cross-sections showed extensive extracellular matrix deposited around the cells and throughout the pore structure of the substrates, which consisted of fibronectin and type I collagen. Cell seeded substrates displayed a significantly higher elastic modulus than unseeded controls similar to native tissue. The transfer of cell growth from two-dimensional to three-dimensional culture resulted in changes in ECM-related gene expression consistent with decreasing cell migration and increasing tissue formation. We found that fibroblasts cultured in three-dimensional substrates expressed significantly higher levels of mRNA for elastin and fibromodulin, while expressing significantly lower levels of mRNA for MMP-1 and hyaluronidase relative to two-dimensional substrates of the same material. The results suggest that three-dimensionally porous, Tecoflex-derived elastic biomaterials may be suitable substrates for engineering vocal fold tissue.

Composite articular cartilage engineered on a chondrocyte-seeded aliphatic polyurethane sponge.

To circumvent the reconstructive disadvantages inherent in resorbable polyglycolic acid (PGA)/polylactic acid (PLA) used in cartilage engineering, a nonresorbable, and nonreactive polyurethane sponge (Tecoflex sponge, TS) was studied as both a cell delivery device and as an internal support scaffolding. The in vitro viability and proliferation of porcine articular chondrocytes (PACs) in TS, and the in vivo generation of new articular cartilage and long-term resorption, were examined. The initial cell attachment rate was 40%, and cell density increased more than 5-fold after 12 days of culture in vitro. PAC-loaded TS blocks were implanted into nude mice, became opalescent, and resembled native cartilage at weeks 12 and 24 postimplantation. The mass and volume of newly formed cartilage were not significantly different at week 24 from samples harvested at week 6 or week 12. Safranin O-fast green staining revealed that the specimens from cell-loaded TS groups at week 12 and week 24 consisted of mature cartilage. Collagen typing revealed that type II collagen was present in all groups of tissue-engineered cartilage. In conclusion, the implantation of PAC-TS resulted in composite tissue-engineered articular cartilage with TS as an internal support. Long-term observation (24 weeks) of mass and volume showed no evidence of resorption.

Synthesis, Electrochemistry, and Imido Transfer Reactions of (TTP)Ti(eta(2)-PhN=NPh).

Treatment of (TTP)Ti(eta(2)-RC&tbd1;CR) (R = Et or Ph) with PhN=NPh results in formation of the azobenzene adduct (TTP)Ti(eta(2)-PhN=NPh) (1) in good isolated yield. Complex 1 reacts with (TTP)Ti(eta(2)-RC&tbd1;CR) at elevated temperatures to cleanly afford 2 equiv of the phenylimido compound, (TTP)Ti=NPh (2). The azobenzene complex, 1, is also formed in low yields by the reaction of the (TTP)Ti=NPh (2) with excess 1,2-diphenylhydrazine. The electrochemistry of the azobenzene adduct (1) and the phenylimido complex (2) is investigated by cyclic voltammetry experiments.

Disulfide-crosslinked hyaluronan-gelatin sponge: growth of fibrous tissue in vivo.

The modification of hyaluronan (HA) and gelatin using dithiobis(propanoic dihydrazide) (DTP) has provided two thiolated macromolecular components of the extracellular matrix (ECM), specifically HA-DTPH and gelatin-DTPH. Blends of these thiolated ECM components were crosslinked in air to form hydrogels that were interpenetrating disulfide-crosslinked networks. Lyophilization of the hydrogels afforded sponge-like macroporous scaffolds suitable for cell attachment and proliferation. Increasing percentages of gelatin-DTPH (0, 25, 50, and 75%) were blended with HA-DTPH, and the resulting sponges were evaluated in vitro and in vivo as scaffolds for tissue engineering by seeding with human tracheal scar (HTS) fibroblasts. While cells failed to attach and grow in HA-only sponges, the gelatin-modified HA sponges promoted cell adhesion, proliferation, and spreading in vitro. Optimal attachment and growth was observed with 50% gelatin-HA sponges. Cell attachment to the gelatin-HA sponge could be blocked by preincubation of cells with a soluble fibronectin peptide Gly-Arg-Gly-Asp (GRGD). Finally, HTS fibroblast-seeded gelatin-HA sponges were implanted into the flanks of nude mice and evaluated at 2 and 8 weeks postimplantation. The sponges were fully biocompatible and new fibrous tissue formed, gradually replacing the sponge-like scaffold. The gelatin-HA sponges act as synthetic, macroporous, covalent mimics of the ECM and constitute novel scaffolds for cell growth and tissue augmentation.

Design and validation of a bioreactor for engineering vocal fold tissues under combined tensile and vibrational stresses.

Criteria are outlined for the design of a bioreactor that can simulate the vibrational stresses in vocal fold movement during speech. Requirements are 0-1 mm amplitudes in the 20-200 Hz frequency range, a variable on-off stress regime, and maintenance of tissue viability over several days. The bioreactor uses dual drivers, one for low frequency (or static) strains, and another for high-frequencies vibrational strains. Response is linear at the driving end for an input of 0-5 V. The amplitude decreases linearly with frequency at constant input voltage, and the phase changes by nearly 180 degrees over the 20-200 Hz range. Human vocal fold fibroblasts were cultured in a polymer substrate and subjected to static and vibrational forces. The results indicate that vibratory strain alters the expression levels of many extracellular matrix-related genes, as well as the spatial distribution of cells and matrix.

The effect of mitomycin on extracellular matrix proteins in a rat wound model.

OBJECTIVE: To evaluate the effect of topical and injected mitomycin on the expression of extracellular matrix proteins by fibroblasts in an early surgical wound model. STUDY DESIGN: A prospective, controlled study in a rat wound model. METHODS: Six linear incisions were placed on the backs of each of three Sprague-Dawley rats, and polyvinyl alcohol sponges were implanted. Two control wounds were implanted with saline-soaked sponges. The two topical test group wounds were treated with 0.5 mg/mL topical mitomycin for 2 minutes, followed by sponge implantation. The two injection test group wounds were injected with 0.3 mL mitomycin (0.5 mg/mL) before incision and sponge implantation. Each incision was closed uniformly with 3-0 nylon suture. The sponges were harvested on the tenth postoperative day. Fibroblasts that had grown into the sponges were separated, and polymerase chain reaction analysis was used to quantify the expression of messenger RNA for several extracellular matrix proteins. RESULTS: The expression of mRNA for some extracellular matrix proteins (elastase, hyaluronidase, and procollagen) was downregulated in the mitomycin test groups. The effect was more pronounced in the topical mitomycin test group compared with the injection test group. The wounds in the topical group were prone to dehiscence, and the wounds in the injection group demonstrated poor healing when compared with controls. CONCLUSIONS: Mitomycin may inhibit wound healing by downregulating the gene expression for extracellular matrix proteins. This effect may be selective and may be more pronounced on inducible genes. Such findings prompt further studies regarding possible "best time" windows and selective gene suppression. The use of mitomycin may be limited in situations where wound integrity is necessary.

Voice, speech, and swallowing outcomes in laser-treated laryngeal cancer.

OBJECTIVE: To describe preliminary voice, speech, and swallowing outcomes in patients treated by endoscopic laser excision of laryngeal cancer with or without adjuvant radiation therapy. STUDY DESIGN: Retrospective review. METHODS: Seventeen surgically treated patients (five T2 glottic and 12 clinically staged T2 supraglottic squamous cell carcinomas) participated in the study. Self-ratings of voice (Voice Handicap Index) and swallowing (M. D. Anderson Dysphagia Inventory) were completed, as well as independent auditory-perceptual ratings of voice and speech recordings. RESULTS: Although no significant difference between Voice Handicap Index, M. D. Anderson Dysphagia Inventory, and listener ratings was identified based on tumor site and irradiation status, there was a trend toward poorer outcomes in patients who received adjuvant radiation therapy. Whereas the patients having supraglottic cancer tended to report better voice but poorer swallowing outcomes, the glottic cancer group displayed the opposite pattern. Severity on Voice Handicap Index correlated significantly with listener severity ratings of speech, suggesting that the patients' perception of their voice handicap was similar to the listeners' judgments of their speech severity. CONCLUSIONS: The results suggest the following trends: 1) Adjuvant radiation therapy was associated with poorer outcomes for voice, speech, and swallowing and may be associated with more impairment than surgery alone and 2) poorer outcomes on voice and swallowing were observed for the glottic and supraglottic cancer groups, respectively. To bolster these preliminary findings, additional outcomes studies in patients treated with conservation therapy are needed.

Chondroitin sulfate hydrogel and wound healing in rabbit maxillary sinus mucosa.

OBJECTIVES/HYPOTHESIS: Chondroitin sulfate (CS) is a glycosaminoglycan in the extracellular matrix of all vertebrates. A biocompatible, nonimmunogenic, pliable hydrogel preparation of CS has recently been produced and has shown benefit in wound healing in murine and porcine epidermis. The objective of the current experiment is to compare the wound healing properties of CS hydrogel versus no treatment in wounds of the maxillary sinus mucosa. STUDY DESIGN: Prospective investigation in an animal model. METHODS: A 6 mm wound was created in bilateral maxillary sinuses of 17 New Zealand white rabbits. CS hydrogel (case) and no dressing (control) were randomly assigned to one side each as wound treatment. Wounds were examined ex vivo at 2, 4, 6, 10, and 14 day postinjury intervals. Wound diameter was measured microscopically by a blinded investigator. Representative specimens were examined histologically. RESULTS: The CS disc was partially integrated into the wounds at the 4-day interval and completely integrated by the 6-day interval. The average wound diameters for the case versus control side were similar at 2 days (3.75 mm vs. 4.42 mm) but differed significantly at 4 days (2.86 mm. vs. 3.80 mm., P =.035). At 6 days, the wounds could not be discerned on either the case or control sides. However, histologic analysis revealed accelerated healing with the CS treatment. The treated wounds displayed respiratory epithelium as opposed to the squamous epithelium exhibited on the untreated sides. CONCLUSIONS: Despite some limitations, the New Zealand white rabbit is an effective model for the study of sinonasal wound healing. CS hydrogel accelerates wound healing in sinonasal mucosa at a 4-day endpoint. We propose that the CS hydrogel acts as a surrogate extracellular matrix, serving as a repository for cytokines and growth factors produced by the regenerating mucosa. It may also provide a structural framework for fibroblasts and epithelial regeneration. Further study is necessary to establish this relationship.

Professional diversity and personal commitments of pediatric otolaryngologists.

OBJECTIVE: To characterize the time demands and practice patterns of pediatric otolaryngologists. DESIGN: Prospective survey of members from the American Society of Pediatric Otolaryngology. RESULTS: The survey response rate was 54% (n = 136) of practicing members of the American Society of Pediatric Otolaryngology. Respondents described being actively engaged in clinical otolaryngology (99%), hospital or practice administration (71%), private enterprise (17%), research (71%), and teaching (89%) on a weekly basis. Sixty percent considered their time demands to be "too busy"; however, few anticipated changing their activities in 5 years. Among the responding physicians, 90% believed that nonotolaryngology peers within their institutions viewed pediatric otolaryngology favorably whereas only 50% thought that other otolaryngologists held the same opinion. CONCLUSIONS: Pediatric otolaryngologists participate in many activities beyond clinical medicine. While most considered their time demands to be too busy, few anticipated a change in their activities. This may be reflective of a high level of job satisfaction, financial constraints, or the relative youth of the subspecialty.

Instability of extracellular matrix gene expression in primary cell culture of fibroblasts from human vocal fold lamina propria and tracheal scar.

Primary fibroblast cell cultures were established from lamina propria of human vocal fold and tracheal scar. There exists a crucial need to provide new tools for studying voice biology, and one of the first steps is the development of a human primary laryngeal cell culture bank. Because cell lines can lose their differentiated phenotype in culture across passages, documentation of gene expression must be determined for passage populations, for us to have knowledge of cell behavior in vitro. Comparison of messenger RNA gene expression of extracellular matrix proteins (procollagen I, collagenase, elastin, hyaluronic acid synthase 2, hyaluronidase, fibronectin, cd44, fibromodulin, and decorin) across cell passages (3, 4, 5, 6, 10, and 12 fornormal laminapropria and 3, 4, 5, 6, and 10 for tracheal scar) revealed varied growth patterns. Cytogenetic analysis demonstrated relative stability of the karyotypes across passages for the tracheal scar cell cultures, whereas the karyotypes of the normal lamina propria fibroblasts showed instability in in vitro cultures. Recommendations for use of primary cell cultures for further studies of gene expression are made.

Genotypic and phenotypic expression of vocal fold polyps and Reinke's edema: a preliminary study.

Although a great deal of research exists regarding lamina propria composition, no report exists that relates gene expression in benign laryngeal lesions to phenotypic markers. In this study, messenger RNA profiles for extracellular matrix proteins--procollagen I, collagenase, elastase, fibronectin, fibromodulin, decorin, hyaluronic acid synthase 2, and hyaluronidase--were completed on 5 polyps and 4 Reinke's edema specimens. These genotypic profiles were correlated to a videostroboscopic parameter of mucosal wave stiffness, which was used as a measurement of phenotypic expression. Polyps, characterized by stiffer mucosal waves, had higher levels of gene expression, whereas stiffer mucosal wave scores for Reinke's edema were associated with lower gene activity levels. This study supports the hypothesis that there is a relationship between genotypic expression found in polyps and Reinke's edema and phenotype as defined by a loss of or a decreased mucosal wave. The study also gives clues as to the proteins responsible for the phenotype.

DNA microarray gene expression analysis of a vocal fold polyp and granuloma.

Genome-wide transcriptional profiling has important applications in advancing knowledge of vocal fold biology. With the use of DNA microarray technology, analysis of global patterns of gene expression can reveal unexpected networks of coordinated regulation in the extracellular matrix of the lamina propria. Transcriptional gene expression patterns for 2 vocal fold pathologies--vocal fold polyp (VP; N = 1) and vocal fold granuloma (VG; N = 1) were analyzed by means of DNA microarray analysis for 4,632 human genes using another patient's true vocal fold (TVF; N = 1) as a control. Twenty-four and 29 genes for VG and VP, respectively, were established to be either over- or underexpressed compared to that of TVF. Five-way cluster analysis revealed broad patterns that suggest a potential degree of organization underlying gene expression in these tissues. For the 1 VG, genes involved represent inflammation and wound healing; for the 1 VP, involved genes demonstrate a tempered wound repair response and increased epithelial manifestations. These results successfully demonstrate the use of DNA microarray technology as a new approach for further investigations dissecting vocal fold disease. Further investigation is needed on larger sample sizes to establish transcriptional gene expression patterns for VP and VG.

Three treatments for teachers with voice disorders: a randomized clinical trial.

Voice problems are a common occupational hazard of teaching school, yet few studies exist that have objectively evaluated treatment approaches aimed at rehabilitating these occupation-related voice disorders. This randomized clinical trial used patient-based treatment outcome measures to evaluate the effectiveness of three treatment programs. Sixty-four teachers with voice disorders were randomly assigned to 1 of 3 treatment groups: voice amplification using the ChatterVox portable amplifier (VA; n = 25), resonance therapy (RT; n = 19), and respiratory muscle training (RMT; n = 20). Before and after a 6-week treatment phase, all teachers completed (a) the Voice Handicap Index (VHI; B. H. Jacobson et al., 1997), an instrument designed to appraise the self-perceived psychosocial consequences of voice disorders, and (b) a voice severity self-rating scale. Both intention-to-treat and as-treated analyses revealed that only the VA and RT groups reported significant reductions in mean VHI scores and in voice severity self-ratings following treatment. Furthermore, results from a posttreatment questionnaire regarding the perceived benefits of treatment showed that compared to RT and RMT, teachers in the VA group reported significantly more overall voice improvement, greater vocal clarity, and greater ease of speaking and singing voice following treatment. These findings replicate previous results from an earlier clinical trial confirming the efficacy of VA and provide new evidence to support RT as an effective treatment alternative for voice problems in teachers. The results are discussed in the context of uneven levels of self-reported compliance and disparate dropout rates among the treatment groups.

Prevalence of voice disorders in teachers and the general population.

Over 3 million teachers in the United States use their voice as a primary tool of trade and are thought to be at higher risk for occupation-related voice disorders than the general population. However, estimates regarding the prevalence of voice disorders in teachers and the general population vary considerably. To determine the extent that teachers are at greater risk for voice disorders, 2,531 randomly selected participants from Iowa and Utah (1,243 teachers and 1,288 nonteachers) were interviewed by telephone using a voice disorder questionnaire. Prevalence-the number of cases per population at risk at a specific time-was determined. The prevalence of reporting a current voice problem was significantly greater in teachers compared with nonteachers (11.0% vs. 6.2%), chi(2)(1) = 18.2, p <.001, as was the prevalence of voice disorders during their lifetime (57.7% for teachers vs. 28.8% for nonteachers), chi(2)(1) = 215.2, p <.001. Teachers were also significantly more likely than nonteachers to have consulted a physician or speech-language pathologist regarding a voice disorder (14.3% vs. 5.5%), chi(2)(1) = 55.3, p <.001. Women, compared with men, not only had a higher lifetime prevalence of voice disorders (46.3% vs. 36.9%), chi(2)(1) = 20.9, p <.001, but also had a higher prevalence of chronic voice disorders (>4 weeks in duration), compared with acute voice disorders (20.9% vs. 13.3%), chi(2)(1) = 8.7, p =.003. To assess the association between past voice disorders and possible risks, adjusted odds ratios (ORs) were estimated using multiple logistic regression. The results identified that being a teacher, being a woman, being between 40 and 59 years of age, having 16 or more years of education, and having a family history of voice disorders were each positively associated with having experienced a voice disorder in the past. These results support the notion that teaching is a high-risk occupation for voice disorders. Important information is also provided regarding additional factors that might contribute to the development of voice disorders.

Voice disorders in teachers and the general population: effects on work performance, attendance, and future career choices.

To examine the frequency and adverse effects of voice disorders on job performance and attendance in teachers and the general population, 2,401 participants from Iowa and Utah (n1 = 1,243 teachers and n2 = 1,279 nonteachers) were randomly selected and were interviewed by telephone using a voice disorder questionnaire. Teachers were significantly more likely than nonteachers to have experienced multiple voice symptoms and signs including hoarseness, discomfort, and increased effort while using their voice, tiring or experiencing a change in voice quality after short use, difficulty projecting their voice, trouble speaking or singing softly, and a loss of their singing range (all odds ratios [ORs] p <.05). Furthermore, teachers consistently attributed these voice symptoms to their occupation and were significantly more likely to indicate that their voice limited their ability to perform certain tasks at work, and had reduced activities or interactions as a result. Teachers, as compared with nonteachers, had missed more workdays over the preceding year because of voice problems and were more likely to consider changing occupations because of their voice (all comparisons p <.05). These findings strongly suggest that occupationally related voice dysfunction in teachers can have significant adverse effects on job performance, attendance, and future career choices.