Vocal nodules (or Singer’s nodules) are benign vocal cord structures which are commonly encountered by clinicians. Though phonetic trauma/abuse is thought to be the main cause of the development of vocal nodules, the exact etiopathogenesis remains unknown. Hence, we compared the immunohistochemical markers for proliferation (Ki-67), apoptosis (TUNEL), growth (EGFR), ischemia (VEGF), inflammation (IL-1α and 10), and immunoreactive innervation (PGP 9.5), in vocal nodule tissue samples obtained from 10 females (17–56 years) and vocal cord tissue from seven controls. A statistically significant increase in Ki-67, TUNEL, EGFR, VEGF and IL-1α expression was noted (p < 0.05) between nodule tissue and control tissue in both epithelial and subepithelial layers. However, the difference was non-significant for both IL-10 and PGP 9.5 (p > 0.05). All markers demonstrated moderate to strong positive correlations, except for IL-10. These findings suggest increased cellular growth and proliferation in vocal nodules coupled with a persistent presence of inflammatory and ischemic environment. Furthermore, global prevalence of apoptotic cells and decreased anti-inflammatory cytokines highlight the presence of underlying complex mechanisms in the etiopathogenesis of vocal nodules, with age having a negligible impact on the marker levels. Our results could potentially further our knowledge in understanding the effects of different treatment modalities available at the cellular level.

Smoking, laryngopharyngeal reflux, and vocal fold abuse can promote the development of Reinke’s oedema, leading to vocal fold dysfunction and injury. The aim of the work was to investigate the appearance and distribution of proliferation marker Ki-67 (Ki-67), interleukin 10 (IL-10), interleukin 1 alpha (IL-1α), and protein gene peptide 9.5 (PGP 9.5) in Reinke’s oedema-affected larynx tissue. Methods: A routine histological and immunohistochemical Reinke’s oedema and control group patient analysis was conducted. We used the biotin–streptavidin biochemical method to detect Ki-67, IL-10, IL-1α, and PGP 9.5 The semiquantitative grading method was used to evaluate immunoreactive cells’ appearance and local distribution. A Mann–Whitney U test and Spearman’s rank coefficient were performed. Results: A low positive correlation between IL-1α epithelial and subepithelial immunoreactive cells in the patient group was found. Mann–Whitney U tests revealed significant patient and control group immunoreactive marker differences. All examined markers showed a higher number of immunoreactive structures in the patient group. Conclusions: Intensive proliferation of the surface epithelium was observed in patient tissues. The notable increase in IL-10 positive structures indicates the dominant anti-inflammatory tissue response. An increased number of IL-1α structures in the larynx epithelium and subepithelium in the patient group is linked to inflammation, proliferation, and tissue remodelling. The PGP 9.5 expression increase is involved in the morphopathogenesis of Reinke’s oedema.

Background: Reinke’s oedema (benign diffuse swelling of the vocal folds) induced various morphological changes occurs in the superficial lamina propria also known as the Reinke’s space. Smoking, laryngopharyngeal reflux and vocal fold abuse can promote the development of this condition as well as lead to vocal fold dysfunction and injury. Patients with Reinke’s oedema complain of vocal problems. 3,47/1000 is estimation of the general population prevalence of Reinke’s oedema. Investigation of the distribution and appearance of Ki-67, IL-1α, IL-10 and PGP 9.5 in Reinke’s oedema-affected larynx tissue compared with control tissue was the aim of the work.Methods: Routine histological and immunohistochemical analysis were applied for specimens with Reinke’s oedema and the control group. Biotin-streptavidin biochemical method was used for detection of Ki-67, PGP 9,5, IL-10 and IL-1α. Immunoreactive cells appearance local distribution were evaluated using semiquantitative grading method. Statistical analysis of the data was performed using nonparametric statistical methods (Mann Whitney U test and Spearman’s rank coefficient).Results: A high positive correlation was found between IL-1α and PGP 9.5 epithelial immunoreactive cells and between epithelial and subepithelial IL-10 cells in the control group. Mann-Whitney U tests revealed significant differences in immunoreactive markers between the patients and the control group. With exception of PGP 9.5 positive subepithelial nerves, all other examined markers revelated higher number of immunoreactive positive structures in the patient tissue.Conclusions: Intensive proliferation of the surface epithelium was observed in Reinke’s oedema affected larynx tissue. Increased expression of IL-1 α structures is linked to tissue remodulation, inflammation and remodulation. Notable increase in IL-10 positive structures is indicating to the dominant anti-inflammatory tissue response. PGP 9.5 expression increase is involved in the morphopathogenesis of Reinke’s oedema.Trial registration: This study was approved by the Ethical Committee of Riga Stradins University, issued on 31-10-2019, No 6-2/2/25.

INTRODUCTION In the vocal arts, it is difficult to determine the exact type of human voice, and it is particularly challenging to identify the voice category of vocalist-beginners because the diapason of the voice has not fully developed. A vocalist often develops his or her voice in an unsuitable tessitura (sings in a wrong voice type) resulting in a loss of sound quality and damage to the voice. An objective metric-based system for the determination of the human voice is needed. The detection for the correlation between the airflow and vital capacity of the lungs, anthropometric data of the singers and the type of the human voice. MATERIALS AND METHODS Sixty vocalists (ten sopranos, ten mezzo-sopranos, ten altos, ten tenors, ten baritones, and ten basses) were examined during this experimental research. All participants were professional singers who have been very successful singing in their voice category for more than five years. The Jaeger spirograph was used to investigate the volume of the peak expiratory flow of representatives of various voice categories, i.e. by measuring the speed of airflow in a time unit (per second). Measurements were made of height, body weight,  vital lung capacity, and volume of the air flow per second in the big, middle and small bronchial tubes. To analyse the results, leading indicators of descriptive statistics were calculated, and one-factor disperses analysis (ANOVA) was used in equivalence testing calculations of the average values of morphological qualities. All statistical calculations were performed with the “Statistics” programme (7.0 edition). RESULTS The average height of the vocalists: sopranos – 165,8; mezzo-sopranos – 168,1; altos – 175,8; tenors – 180,5; baritones – 187,5; basses – 188,2. The average weight of the singers (kg): sopranos – 60,2; mezzo-sopranos – 70,5; altos – 74,1; tenors - 87,7; baritones – 91,4; basses – 92,6. The average vital lung capacity of the singers (L): sopranos – 3,79; mezzo-sopranos – 3,96; altos – 4,35; tenors 5,13; baritones – 6,06; basses – 6,12. The average peak expiratory flow of the singers per second (L/s): sopranos – 7,44; mezzo-sopranos – 7,43; altos – 8,19; tenors – 9,80; baritones - 11,49; basses – 11,2. The average volume of the air flow per second in the big bronchial tubes of the singers(L/s): sopranos – 6,49; mezzo-sopranos – 9,29; altos – 7,42; tenors – 7,91; baritones – 10,07; basses – 9,77. The average volume of the air flow per second in the middle bronchial tubes of the singers (L/s): sopranos – 4,60; mezzo-sopranos – 4,02; altos – 4,96; tenors 4,46; baritones – 5,79; basses – 5,73. The average volume of the air flow per second in the small bronchial tubes of the singers (L/s): sopranos – 1,98; mezzo-soprano – 1,49; altos – 1,99; tenors – 1,69; baritones – 2,24; basses – 2,17. There was a correlation between the airflow results e.a. Vital capacity, MEF 75 MEF 50 and PEF and the type of human voice, but there was no correlation between PEF 25 and the type of human voice. There was a positive correlation between anthropometric data like weight and height and the pitch of the voice. CONCLUSION There is a correlation between the type of human voice and a person's height, weight as well as their vital lung capacity and peak expiratory flow. According to our research data, an algorithm could be made for the determination of the type of human voice to avoid voice damage and health problems related to the forced use of the voice in a wrong pitch.