Publications

Elizabeth DiRenzo, PhD
Assistant Professor of Otolaryngology — Head & Neck Surgery and, by courtesy, of Music

Publications

  • Establishing a Mouse Model of Surgical Vocal Fold Injury. The Laryngoscope Kimura, A., Khan, M. I., Easwaran, M., Soo, J., Golchin, A., Erickson-DiRenzo, E. 2024

    Abstract

    Animal models of vocal fold (VF) surgical injury and scar formation provide insight into the wound healing process. The purpose of this study was to establish an alternative model of surgical injury to the mouse VF using materials commonly available in most research laboratories or for purchase and to investigate wound healing of the epithelium (EP) and lamina propria (LP).Mice were anesthetized by isoflurane gas delivery and positioned on a platform so that the larynx could be observed using a laryngoscope and dissection microscope. Unilateral VF injury was created using a wire brush. Mice were euthanized and the larynx evaluated 1-, 3-, 5-, 7-, 14-, and 28-days following injury. Histological and immunofluorescent analysis was used to evaluate thickness of the EP, LP area, proliferative (Ki67+) and basal cells (p63+) in the EP, and collagen III content in the LP.The depth of injury reached the superficial thyroarytenoid muscle on Day 1. The thickness of the EP of the injured VF was increased on Days 3 and 5, and the LP area was increased on Days 3, 5, and 7 as compared with the uninjured VF. Ki67+ and p63+ cells were increased on Day 3 and collagen III content was increased on Days 5 and 28 as compared with the uninjured VF.We successfully established an alternative method of creating unilateral VF injury in the mouse. This method will be useful for future research regarding VF surgical injury and wound healing.N/A Laryngoscope, 2024.

    View details for DOI 10.1002/lary.31732

    View details for PubMedID 39180435

  • Effects of Short-term Electronic(e)-Cigarette Aerosol Exposure in the Mouse Larynx. The Laryngoscope Easwaran, M., Maria, C. S., Martinez, J. D., Hung, B., Yu, X., Soo, J., Kimura, A., Gross, E. R., Erickson-DiRenzo, E. 2023

    Abstract

    The effects of electronic cigarettes (e-cigarettes) on the larynx are relatively unknown. This study examined the short-term effects of e-cigarette inhalation on cellular and inflammatory responses within the mouse laryngeal glottic and subglottic regions after exposure to pod-based devices (JUUL).Male C57BL6/J mice (8-9 weeks) were assigned to control (n = 9), JUUL flavors Mint (JMi; n = 10) or Mango (JMa; n = 10). JUUL mice were exposed to 2 h/day for 1, 5, and 10 days using the inExpose inhalation system. Control mice were in room air. Vocal fold (VF) epithelial thickness, cell proliferation, subglandular area and composition, inflammatory cell infiltration, and surface topography were evaluated in the harvested larynges. Mouse body weight and urinary nicotine biomarkers were also measured. Chemical analysis of JUUL aerosols was conducted using selective ion flow tube mass spectrometry.JUUL-exposed mice had reduced body weight after day 5. Urinary nicotine biomarker levels indicated successful JUUL exposure and metabolism. Quantitative analysis of JUUL aerosol indicated that chemical constituents differ between JMi and JMa flavors. VF epithelial thickness, cellular proliferation, glandular area, and surface topography remained unchanged after JUUL exposures. Acidic mucus content increased after 1 day of JMi exposure. VF macrophage and T-cell levels slightly increased after 10 days of JMi exposures.Short-term e-cigarette exposures cause minimal flavor- and region-specific cellular and inflammatory changes in the mouse larynx. This work provides a foundation for long-term studies to determine if these responses are altered with multiple e-cigarette components and concentrations.N/A Laryngoscope, 2023.

    View details for DOI 10.1002/lary.31043

    View details for PubMedID 37698394

  • End-to-end deep learning classification of vocal pathology using stacked vowels LARYNGOSCOPE INVESTIGATIVE OTOLARYNGOLOGY Liu, G. S., Hodges, J. M., Yu, J., Sung, C., Erickson-DiRenzo, E., Doyle, P. C. 2023

    View details for DOI 10.1002/lio2.1144

    View details for Web of Science ID 001065156000001

  • Method for Collecting Single Epithelial Cells from the Mouse Larynx. The Laryngoscope Khan, M. I., Easwaran, M., Martinez, J. D., Kimura, A., Erickson-DiRenzo, E. 2023

    Abstract

    The larynx is lined by specialized epithelial cell populations. Studying molecular changes occurring in individual epithelial cell types requires a reliable method for removing these cells from the larynx. Our objective was to develop a method to harvest individual epithelial cells from the mouse larynx while minimizing contamination from non-laryngeal sites and non-epithelial laryngeal cells.Mice were euthanized, and the larynx was carefully exposed and separated from non-laryngeal sites. A small dental brush was inserted into the laryngeal inlet and rotated to obtain epithelial cells. Cells were transferred to collection media, counted, and cytospin preparations stained for laryngeal epithelial (i.e., Pan-Keratin, EpCAM, NGFR, p63, K5, β-tubulin, MUC5AC) and non-epithelial (i.e., vimentin) cell markers. Histopathology was completed on brushed laryngeal tissue sections to evaluate the depth of cell collection. Preliminary Single-cell RNA sequencing (scRNA-seq) was performed to confirm this method can capture diverse laryngeal cell types.We collected 6000-8000 cells from a single larynx and 35000-40000 cells from combining brushings from three tissues. Histopathology demonstrated brushing removed the epithelial layer of the larynx and some underlying tissue. Immunofluorescence staining demonstrated the phenotype of harvested cells was primarily epithelial. Preliminary scRNA-seq was successfully conducted and displayed nine unique cell clusters.We developed a reliable method of harvesting individual epithelial cells from the mouse larynx. This method will be useful for collection of laryngeal cells for a variety of downstream cellular and molecular assays, including scRNA-seq, protein analyses, and cell-culture-based experiments, following laryngeal injury.N/A Laryngoscope, 2023.

    View details for DOI 10.1002/lary.30970

    View details for PubMedID 37602769

  • Impact of Electronic Cigarettes on the Upper Aerodigestive Tract: A Comprehensive Review for Otolaryngology Providers OTO OPEN Soo, J., Easwaran, M., Erickson-DiRenzo, E. 2023; 7 (1)

    View details for DOI 10.1002/oto2.25

    View details for Web of Science ID 000937521100001

  • Diagnosis and Management of Vocal Complications after Chondrolaryngoplasty. The Laryngoscope Nuyen, B., Qian, Z. J., Rakkar, M., Thomas, J. P., Erickson-DiRenzo, E., Sung, C. K. 2022

    Abstract

    OBJECTIVE: Transfeminine patients (transwomen/feminine nonbinary folks assigned male at birth) can undergo chondrolaryngoplasty ("tracheal shave") to feminize their neck appearance. While isolated cases of vocal complications have been reported following the procedure, aggregated outcomes have not been quantitatively studied. We present acoustic and stroboscopic data to describe a patient cohort with vocal complications after chondrolaryngoplasty and discuss reparative surgical technique.METHODS: Subjective and objective data, including videostroboscopy, were collected from patients with voice complaints after chondrolaryngoplasty. Dislocated anterior commissures were reconstructed with feminization laryngoplasty. Postoperative voice data were recorded and statistically compared to preoperative data using paired t-tests.RESULTS: On consecutive chart review, of the 94 transfeminine women with prior outside history of chondrolaryngoplasty, 27 (29%) reported chronic postoperative hoarseness, deepened pitch, or loss of upper register. On endoscopy, short, lax vocal folds with persistent anterior glottic gap and phase asymmetry were commonly noted; anterior commissure dislocation was confirmed in-office by using needle localization through absent thyroid cartilage. After open resuspension of the anterior commissure with feminization laryngoplasty, post-repair modal-speaking, minimum, and maximum fundamental frequencies (F0) increased on average by 7, 8, and 5 semitones, respectively (p<0.01), when compared to pre-repair values. On average, perioperative maximum phonation time did not change significantly (p=0.15). Average self-assessment of vocal femininity increased by 48% (p<0.01).CONCLUSION: Anterior commissure dislocation should be suspected with signs of vocal impairment after chondrolaryngoplasty. Following proper diagnosis, resuspension of the anterior commissure via feminization laryngoplasty approach can be an effective reparative technique.LEVEL OF EVIDENCE: This work represents a 2011 OCEBM Level 4 evidence as a case series Laryngoscope, 2022.

    View details for DOI 10.1002/lary.30518

    View details for PubMedID 36576093

  • Social Perception of External Laryngeal Anatomy Related to Gender Expression in a Web-based Survey. The Laryngoscope Kiessling, P., Balakrishnan, K., Fauer, A., Sanan, A., McDonald, D., Thomas, J., Erickson-Direnzo, E., Sung, C. K., Nuyen, B. 2022

    Abstract

    To quantify the effect of laryngeal prominence size on socially perceived attributes relating to gender expression. Chondrolaryngoplasty ("tracheal shave") is a common procedure performed for transgender women to feminize neck appearance. The extent of thyroid cartilage resection needed to convey socially-perceived feminine gender expression without destabilizing the voice is incompletely understood.Cross-sectional evaluation of a randomized allocation of images of varying laryngeal prominence to a non-repeated, random sample from November 2021 to December 2021. Photos of laryngeal prominence were isolated against a constant neck baseline with lateral, oblique, and frontal views. The images were embedded into a web-based survey with visual analog scales to capture perceived scaled gender expression (masculinity, femininity) and social traits (e.g., attractiveness, friendliness, leadership). We performed bivariate and multivariate analyses relating the laryngeal prominence to perceived gender expression and social traits.The analytic sample included 1,026 respondents. Laryngeal grades similar to the demonstrated "grade M" in this study and smaller demonstrated similar perceptions of increased femininity and decreased masculinity. Grades larger than M demonstrate significantly increased perceived masculinity and significantly decreased perceived femininity. The lateral and oblique views of the neck appear to be the most gender-informative.This crowd-sourced analysis of external laryngeal anatomy by a large population of observers provides clear, reproducible insights into social perceptions of gender identity and specifically femininity. These data will meaningfully inform patient counseling and surgical planning for gender-affirming interventions by establishing normative data representing the general public's perceptions.N/A Laryngoscope, 2022.

    View details for DOI 10.1002/lary.30498

    View details for PubMedID 36453533

  • Effects of Electronic (E)-cigarette Vapor and Cigarette Smoke in Cultured Vocal Fold Fibroblasts. The Laryngoscope Martinez, J. D., Easwaran, M., Ramirez, D., Erickson-DiRenzo, E. 2022

    Abstract

    OBJECTIVE: The public use of electronic-cigarettes (e-cigs) is rapidly growing. When heated, e-cigs produce a vapor that is inhaled. The vocal folds are among the first tissues exposed to this insult. However, the impact of e-cigs on vocal fold health is almost entirely unknown. Our objective was to evaluate the effects of e-cig vapor on cultured human vocal fold fibroblasts (hVFFs), the primary cell type of the lamina propria. We compared the cellular effects of e-cig vapor without and with nicotine and conventional cigarette smoke.STUDY DESIGN: In vitro.METHODS: E-cig vapor extract (EVE) and cigarette smoke extract (CSE) were created by bubbling vapor and smoke, respectively, into the cell culture medium. hVFFs were exposed to EVE without or with nicotine or CSE for 24hours. Untreated cells were used as a control group. Cells were harvested, and cytotoxicity, extracellular matrix and inflammatory gene expression, and DNA damage were assessed.RESULTS: Undiluted EVE without and with nicotine reduced the viability of hVFFs to a cytotoxic level. CSE reduced hVFFs viability to a greater extent than EVE and induced DNA damage as measured by DNA double-strand breaks. No changes in gene expression were observed following EVE or CSE exposure.CONCLUSION: EVE induces cytotoxicity in hVFFs. However, cellular responses were greater following exposure to CSE, suggesting cigarette smoke may induce more harm, at least in the short term. Findings from this investigation improve our understanding of responses of hVFFs to e-cigs and form the basis for an in vitro methodology to study the vocal fold responses to these products.LEVEL OF EVIDENCE: N/A Laryngoscope, 2022.

    View details for DOI 10.1002/lary.30073

    View details for PubMedID 35213064