Cigarette Smoke Exposure to Pig Larynx in an Inhalation Chamber

Voice Disorder Prevalence and Vocal Health Characteristics in Children

Importance

Voice disorders impede communication and limit quality of life for many children. However, research demonstrating the prevalence of pediatric voice problems and associated voice use patterns is scarce. This investigation examined the prevalence of voice problems and vocal health characteristics of school-aged children.

Objective

To examine the prevalence of voice problems in school-aged children throughout the US with reference to lifestyle, demographic characteristics, and voice use patterns.

Design, Setting, and Participants

This study used a cross-sectional design to survey a probability sample of caregivers of children aged 4 to 12 years living throughout the US in 2023.

Main Outcomes and Measures

Caregivers were surveyed regarding their children's voice use, voice symptoms, voice problems, extracurricular activities, and demographic information. Caregivers also competed the Pediatric Voice-Related Quality of Life questionnaire. The Fisher exact test, χ2 tests, and logistic regression were used to compare children with and without voice problems.

Results

Overall, 6293 panelists were invited to complete screening questions for the survey, and 1789 individuals were screened for eligibility between March and April 2023. Of these, 1175 parents (65.7%) completed the survey. Twenty-one (1.8%) were excluded for a combination of either high refusal rates (n = 16), speeding (n = 2), or straight lining (n = 12). The final number of participants included in analysis was 1154 caregivers of children aged 4 to 12 years (559 female children [48.4%]; 595 male children [51.6%]; mean [SD] age, 8.02 [2.49] years). The prevalence of voice problems in children was 6.7% (n = 78), and the lifetime prevalence was 12% (n = 138). Benign vocal fold lesions was the most common diagnosis underlying voice complaints, and other causes included respiratory illness, allergies, autism-related voice issues, and other neurological conditions. Risk factors for pediatric voice problems included being male (odds ratio [OR], 1.47; 95% CI, 1.0-2.1), having more than 4 individuals living in the household (OR, 2.30; 95% CI, 1.2-4.4), poor speech intelligibility (OR, 2.26; 95% CI, 1.2-4.3), maternal history of voice problems (OR, 4.54; 95% CI, 1.2-16.4), participating in online gaming (OR, 1.56; 95% CI, 1.0-2.3), and secondhand smoke exposure (OR, 1.7; 95% CI, 1.1-2.6). Voice use-related risk factors included frequent talking, coughing, throat clearing, tantrums/crying, and vocal strain. Voice problems were associated with substantially detracted quality of life as measured by the Pediatric Voice-Related Quality of Life questionnaire, limited social/extracurricular interactions, increased school absences, and negative attention from adults.

Conclusions

The results of this survey study suggest that pediatric voice problems are relatively common and detract from quality of life. Specific environmental and behaviorial factors are associated with increased risk for voice disorders.

Modulation of mouse laryngeal inflammatory and immune cell responses by low and high doses of mainstream cigarette smoke

Cigarette smoking is a major risk factor for laryngeal diseases. Despite well-documented cigarette smoke (CS) induced laryngeal histopathological changes, the underlying immunopathological mechanisms remain largely unexplored. The goal of this study was to evaluate inflammatory and immune cell responses in a CS-exposed larynx. Specifically, we used a 4-week subacute whole-body CS inhalation mouse model to assess these responses in the laryngeal mucosa upon exposure to low (LD; 1 h/day) and high dose (HD; 4 h/day) CS. Laryngeal tissues were harvested and evaluated using a 254-plex NanoString inflammation panel and neutrophil/macrophage/T-cell immunohistochemistry (IHC). NanoString global and differential gene expression analysis revealed a unique expression profile only in the HD group, with 26 significant differentially expressed genes (DEGs). StringDB KEGG pathway enrichment analysis revealed the involvement of these DEGs with pro-inflammatory pathways including TNF/TNFα and IL-17. Furthermore, inflammatory responses remained inhibited in conjunction with predicted activated states of anti-inflammatory regulators like PPARγ and NFE2L2 upon Ingenuity Pathway Analysis (IPA). Subglottic T-cell levels remained significantly inhibited as corroborated by IPA predictions. Overall, our key findings are consistent with HD exposures being anti-inflammatory and immunosuppressive. Furthermore, the identification of important regulatory genes and enriched pathways may help improve clinical interventions for CS-induced laryngeal diseases.

Eliciting and Characterizing Porcine Vocalizations: When Pigs Fly

BACKGROUND/OBJECTIVES

While voice-related therapeutic interventions are often researched preclinically in the porcine model, there are no well-established methods to induce porcine glottic phonation. Described approaches, such as training animals to phonate for positive reinforcement are time-consuming and plagued by inherent variability in the type of phonation produced and contamination of background noise. Thus, a reliable method of assessing glottic phonation in the porcine model is needed.

METHODS

In this study, we have created a novel pulley-based apparatus with harness for "pig-lifting" with surrounding acoustic insulation and high-directional microphone with digital recorder for recording phonation. Praat and Matlab were used to analyze all porcine vocalizations for fundamental frequency (F0), intensity, duration of phonation and cepstral peak prominence (CPP). Glottic phonation was detected using F0 (≥2000 hz), duration (≥3 seconds) and researcher perceptual judgment. Partial-glottic phonations were also analyzed. Reliability between researcher judgment and acoustic measures for glottic phonation detection was high.

RESULTS

Acoustic analysis demonstrated that glottic and partial-glottic phonation was consistently elicited, with no formal training of the minipigs required. Glottic vocalizations increased with multiple lifts. Glottic phonation continued to be elicited after multiple days but became less frequent. Glottic and partial-glottic phonations had similar CPP values over the 6 experimental days.

CONCLUSION

Our cost-effective, reliable method of inducing and recording glottic phonation in the porcine model may provide a cost effective, preclinical tool in voice research.

Short-term whole body cigarette smoke exposure induces regional differences in cellular response in the mouse larynx

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Short-term CSE induced regional differences in murine laryngeal cellular responses.

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Basal cell hyperplasia accompanies adaptive cell proliferation in the vocal folds.

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Increased subglottic cell proliferation persists even after CS cessation.

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SEM revealed vocal fold microprojection damage with possible necrotic features.

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Subglandular acidic mucins decreased and neutral mucins increased post-CSE.

The larynx is an essential organ in the respiratory tract and necessary for airway protection, respiration, and phonation. Cigarette smoking is a significant risk factor associated with benign and malignant laryngeal diseases. Despite this association, the underlying mechanisms by which cigarette smoke (CS) drives disease development are not well elucidated. In the current study, we developed a short-term murine whole body inhalation model to evaluate the first CS-induced cellular responses in the glottic [i.e. vocal fold (VF)] and subglottic regions of the larynx. Specifically, we investigated epithelial cell proliferation, cell death, surface topography, and mucus production, at various time points (1 day, 5 days, 10 days) after ∼ 2 h exposure to 3R4F cigarettes (Delivered dose: 5.6968 mg/kg per cigarette) and following cessation for 5 days after a 5 day CS exposure (CSE). CSE elevated levels of BrdU labeled proliferative cells and p63 labeled epithelial basal cells on day 1 in the VF. CSE increased proliferative cells in the subglottis at days 5, 10 and following cessation in the subglottis. Cleaved caspase-3 apoptotic activity was absent in VF at all time points and increased at day 1 in the subglottis. Evaluation of the VF surface by scanning electron microscopy (SEM) revealed significant epithelial microprojection damage at day 10 and early signs of necrosis at days 5 and 10 post-CSE. SEM visualizations additionally indicated the presence of deformed cilia at days 5 and 10 after CSE and post-cessation in the respiratory epithelium lined subglottis. In terms of mucin content, the impact of short-term CSE was observed only at day 10, with decreasing acidic mucin levels and increasing neutral mucin levels. Overall, these findings reveal regional differences in murine laryngeal cellular responses following short-term CSE and provide insight into potential mechanisms underlying CS-induced laryngeal disease development.

Exploring the Pathophysiology of Reinke's Edema: The Cellular Impact of Cigarette Smoke and Vibration

Objectives

To explore the isolated or combined effects of cigarette smoke extract (CSE) and vibration on human vocal fold fibroblasts (hVFF) in an in vitro setting in order to elucidate their influence in the pathophysiology of Reinke's edema (RE).

Study design

Immortalized hVFF were exposed to CSE or control medium under static or vibrational conditions. A phonomimetic bioreactor was used to deliver vibrational patterns to hVFF over a period of 5 days.

Methods

Cytotoxicity was quantified using a lactate dehydrogenase assay. We employed reverse transcription–quantitative polymerase chain reaction, enzyme‐linked immunosorbent assay, and Magnetic Luminex^(R) assays (R&D Systems, Minneapolis, MN) to assess the influence on extracellular matrix production, fibrogenesis, inflammation, and angiogenesis.

Results

We observed significant changes induced by CSE alone (hyaluronic acid, matrix metalloproteinase 1, Interleukin‐8, cyclooxygenase [COX]1, COX2, vascular endothelial growth factor [VEGF]D), as well as settings in which only the combination of CSE and vibration led to significant changes (transforming growth factor beta 1, VEGFA, VEGFC). Also, CSE‐induced levels of COX2 were only significantly reduced when vibration was applied.

Conclusion

We were able to explore the cellular effects of CSE and vibration on hVFF by employing a phonomimetic bioreactor. Whereas cigarette smoke is generally accepted as a risk factor for RE, the role of vibration remained unclear as it is difficult to study in humans. Our data showed that some genes and proteins in the pathophysiological context of RE were only affected when CSE in combination with vibration was applied.

Level of Evidence

NA Laryngoscope, 131:E547–E554, 2021

Evaluating the effects of smoking on the voice and subjective voice problems using a meta-analysis approach

The objectives of this study were to identify the effects of smoking on the voice of smokers and present the baseline data for establishing the basis for preventing voice disorders. This study was evaluated using a meta-analysis from studies published between Jan 1, 2000, and Nov 15, 2018. As a result, the final meta-analysis was conducted using nine papers. The standard mean difference was analyzed after dividing the effects of smoking on voice into the pitch (F0), sound quality (jitter, shimmer, and noise to harmonic ratio; NHR), Maximum Phonation Time (MPT), and subjective voice problem. The results showed that there was a significant difference in F0 and MPT. On the other hand, the jitter, shimmer, NHR, and Voice Handicap Index (VHI) had different mean effect size but they were not significantly different. The analysis by sub-function of VHI results showed that the mean effect size was significantly different only in VHI-P (Physical). This study evaluated the effects of smoking on voice using meta-analysis. It was confirmed that smoking had significant and moderate effects on the F0 of voice, MPT, VHI, and physical functions. It is necessary for future meta-analysis studies to conduct randomized controlled experiments or longitudinal studies to confirm the effect sizes of variables.

In Vitro Models, Standards, and Experimental Methods for Tobacco Products

Traditional tobacco products have well-known systemic and local oral effects, including inflammation, vasoconstriction, delayed wound healing, and increased severity of periodontal disease. Specifically in the oral cavity and the lung, cigarette smoking produces cancer, increased infectivity, acute and chronic inflammation, changes in gene expression in epithelial lining cells, and microbiome changes. In recent years, cigarette smoking has greatly decreased in the United States, but the use of new tobacco products has gained tremendous popularity. Without significant knowledge of the oral sequelae of products such as electronic cigarettes, researchers must evaluate current in vitro and in vivo methods to study these agents, as well as develop new tools to adequately study their effects. Some in vitro testing has been performed for electronic cigarettes, including toxicologic models and assays, but these mostly study the effect on the respiratory tract. Recently, direct exposure of the aerosol to in vitro 3-dimensional tissue constructs has been performed, demonstrating changes in cell viability and inflammatory cytokines. For in vivo studies, a universal e-cigarette testing machine or standard vaping regime is needed. A standard research electronic cigarette has recently been developed by the National Institute of Drug Abuse, and other devices delivering aerosols with different nicotine concentrations are becoming available. One of the biggest challenges in this research is keeping up with the new products and the rapidly changing technologies in the industry.