A dysphagia model with denervation of the pharyngeal constrictor muscles in guinea pigs: functional evaluation of swallowing.

Introduction: Swallowing impairment is a crucial issue that can lead to aspiration, pneumonia, and malnutrition. Animal models are useful to reveal pathophysiology and to facilitate development of new treatments for dysphagia caused by many diseases. The present study aimed to develop a new dysphagia model with reduced pharyngeal constriction during pharyngeal swallowing.

Transient Receptor Potential Ankyrin 1 Channel Alters Transforming Growth Factor Beta 1/Smad Signaling in Rat Vocal Fold Fibroblasts.

Objectives: Vocal fold scar remains a therapeutic challenge. Vocal fold fibroblasts (VFFs) secrete extracellular matrix (ECM), and transforming growth factor-beta 1 (TGF-β1)-mediated fibroblast to myofibroblast differentiation is central to the development of fibrosis. The transient receptor potential (TRP) channel superfamily is a group of nonselective cation channels, and activation of TRP ankyrin 1 (TRPA1) channel has been shown to have antifibrotic effects through TGF-β1/Smad signaling in various organs.

Sustained Effects of Capsaicin Infusion into the Oropharynx on Swallowing in Perfused Rats.

Objectives: To examine the sustained effects of oropharyngeal capsaicin stimulation on the regulation of swallowing, we recorded the swallowing-related nerve activities during continuous infusion of capsaicin solution into the oropharynx.

Methods: In 33 in situ perfused brainstem preparation of rats, we recorded the activities of the vagus, hypoglossal, and phrenic nerves during fictive swallowing. The interburst intervals (IBIs) of the swallowing-related nerves during sequential pharyngeal swallowing (sPSW) elicited by electrical stimulation of the superior laryngeal nerve (SLN) during concurrent capsaicin stimulation of 10, 1, and 0.

Complementary Effect of Transcutaneous Cervical Stimulation by Interferential Current on Functional Dysphonia.

Objectives: Functional dysphonia (FD) varies in terms of vocal behavior and treatment efficacy. So-called hypofunctional dysphonia is characterized by insufficient subglottal pressure which causes a lack of driving power needed to vibrate the vocal folds leading to weak voice or aphonia in severe cases. While voice therapy is the initial treatment, some patients fail to respond to it.

Effect of pharmacological inhibition of the pontine respiratory group on swallowing interneurons in the dorsal medulla oblongata.

Objectives: To examine the role of neurons of the pontine respiratory group (PRG) overlapping with the Kölliker-Fuse nucleus in the regulation of swallowing, we compared the activity of swallowing motor activities and interneuron discharge in the dorsal swallowing group in the medulla before and after pharmacological inhibition of the PRG.

Methods: In 23 in situ perfused brainstem preparation of rats, we recorded the activities of the vagus (VNA), hypoglossal (HNA), and phrenic nerves (PNA), and swallowing interneurons of the dorsal medulla during fictive swallowing elicited by electrical stimulation of the superior laryngeal nerve or oral water injection. Subsequently, respiratory- and swallow-related motor activities and single unit cell discharge were assessed before and after local microinjection of the GABA-receptor agonist muscimol into the area of PRG ipsilateral to the recording sites of swallowing interneurons.

The Effects of Amniotic Membrane Transplantation on Vocal Fold Regeneration.

Objectives/hypothesis: Vocal fold (VF) scar and sulcus cause severe vocal problems, but optimal methods have not been established. Total replacement of the mucosa is required particularly for cases in which the whole lamina propria is occupied by severe fibrosis and vibratory function is totally lost. The amniotic membrane (AM) has been proven to have regenerative potential, as it contains stem cells and growth factors.

Anti-inflammatory and Antioxidant Effects of Japanese Herbal Medicine Kyoseihatekigan on Vocal Fold Wound Healing.

Objectives: The Japanese herbal medicine kyoseihatekigan (KHG) has been used to alleviate the symptoms of croaky voice and globus hystericus, and each of its components has anti-inflammatory and antioxidant effects. However, the mechanisms underlying these beneficial actions of KHG on the vocal folds remain largely unknown. We examined the effects of KHG on rat vocal fold wound healing and assessed its anti-inflammatory and antioxidant properties.

Firing characteristics of swallowing interneurons in the dorsal medulla during physiologically induced swallowing in perfused brainstem preparation in rats.

Oropharyngeal swallowing is centrally mediated by a swallowing central pattern generator (Sw-CPG) in the medulla oblongata. The activity of the Sw-CPG depends on the sensory inputs determined by physical and chemical bolus properties. Here we investigate the sensory-motor integration during swallowing arising from different sensory sources.

Physiological Effects of Voice Therapy for Aged Vocal Fold Atrophy Revealed by EMG Study.

Objectives: Age-related voice changes are characterized as breathy, weak and strained, and a deterioration in vocal function in the elderly has been putatively linked to a reduced intensity of speech. They contribute to undesirable voice changes known as presbyphonia. These changes are caused by histological alterations in the lamina propria of the vocal fold mucosa and atrophy of the thyroarytenoid muscle, as well as by decreased respiratory support.

Extracellular acidity in tumor tissue upregulates programmed cell death protein 1 expression on tumor cells via proton-sensing G protein-coupled receptors.

Acidity in the tumor microenvironment has been reported to promote cancer growth and metastasis. In our study, we examined a potential relation between extracellular acidity and expression level of the immune checkpoint molecule programmed cell death protein 1 (PD-L1) in murine squamous cell carcinoma (SCC) and melanoma cell lines. PD-L1 expression in the tumor cells was upregulated by culturing in a low pH culture medium.

Effects of Repeated Intracordal Glucocorticoid Injection on the Histology and Gene Expression of Rat Vocal Folds.

Objectives: Local injection of glucocorticoids (GCs) into the vocal folds has been used for treating the vocal fold lesions. While the positive effects on vocal fold nodules, polyps, or scarring have been clinically reported, some concern remains around the potential adverse effects such as vocal fold atrophy, and the mechanisms remain unclear. The present study examined the histology and gene expression of locally injected GC into the vocal folds in rats.

Mechanisms Underlying the Antifibrotic Potential of Estradiol for Vocal Fold Fibrosis.

Objectives/hypothesis: Vocal fold fibrosis remains a significant clinical challenge. Estrogens, steroid hormones predominantly responsible for secondary sexual characteristics in women, have been shown to alter wound healing and limit fibrosis, but the effects on vocal fold fibrosis are unknown. We sought to elucidate the expression of estrogen receptors and the effects of estrogens on TGF-β1 signaling in rat vocal fold fibroblasts (VFFs).

Influences of GABAergic Inhibition in the Dorsal Medulla on Contralateral Swallowing Neurons in Rats.

Objectives: We aimed to examine the effect of unilateral inhibition of the medullary dorsal swallowing networks on the activities of swallowing-related cranial motor nerves and swallowing interneurons.

Methods: In 25 juvenile rats, we recorded bilateral vagal nerve activity (VNA) as well as unilateral phrenic and hypoglossal activity (HNA) during fictive swallowing elicited by electrical stimulation of the superior laryngeal nerve during control and following microinjection of the GABA agonist muscimol into the caudal dorsal medulla oblongata in a perfused brainstem preparation. In 20 animals, swallowing interneurons contralateral to the muscimol injection side were simultaneously recorded extracellularly and their firing rates were analyzed during swallowing.

Intracordal Injection of Basic Fibroblast Growth Factor in 100 Cases of Vocal Fold Atrophy and Scar.

Objectives/hypothesis: Vocal fold atrophy, scar, and sulcus reduce the vibratory function of the vocal fold mucosa, which causes severe refractory dysphonia. We have reported encouraging preliminary results using an intracordal injection of basic fibroblast growth factor (bFGF) and showed improvement in phonatory parameters and voice. The present study summarizes our experience with 100 cases of stiffened vocal folds that were treated with bFGF injections.

Comparison of Three Fractionation Schedules in Radiotherapy for Early Glottic Squamous Cell Carcinoma.

Background/aim: Radiotherapy is widely accepted as the treatment of choice for early glottic squamous cell carcinoma (EGSCC), although it varies greatly with respect to dose, dose per fraction, and treatment techniques. The study aim was to evaluate the use of accelerated fractionation strategy (AFS) for EGSCC in standard clinical practice.

Patients And Methods: Patients treated with definitive radiotherapy for EGSCC between 2008 and 2019 were retrospectively identified and received either conventional fractionation, hypofractionation, or hyperfractionation.

Effects of Voice Therapy for Dysphonia due to Tension Imbalance in Unilateral Vocal Fold Paralysis and Paresis.

Objectives: Medialization procedures, such as type I thyroplasty, arytenoid adduction, and vocal fold injection, are popular treatments for dysphonia due to unilateral vocal fold paralysis (UVFP). However, dysphonia occasionally persists after medialization procedures owing to tension imbalance. This tension imbalance causes diplophonia, asymmetry and aperiodic vibrational flutter in travelling wave motion.

Intracellular activity of pharyngeal motoneurons during breathing, swallowing, and coughing.

We recorded membrane potentialp changes in 45 pharyngeal motoneurons (PMs) including 33 expiratory modulated and 12 nonrespiratory neurons during breathing, swallowing, and coughing in decerebrate paralyzed cats. Four types of membrane potential changes were observed during swallowing: ) depolarization during swallowing ( = 27), ) depolarization preceded by a brief (≤ 0.1 s) hyperpolarization ( = 4), ) longer term (> 0.

Laryngeal afferent modulation of swallowing interneurons in the dorsal medulla in perfused rats.

Objectives: The purpose of this study was to investigate the influence of laryngeal afferent inputs on brainstem circuits that mediate and transmit swallowing activity to the orofacial musculature.

Methods: Experiments were performed on 19 arterially perfused juvenile rats. The activities of swallowing interneurons in relation to their respective motor outputs in the hypoglossal and vagus nerves were assessed during fictive swallowing with or without concurrent laryngeal sensory stimulation at intensities of 20, 40, and 60 μA.

Effect of Voice Therapy Using Semioccluded Vocal Tract Exercises in Singers and Nonsingers With Dysphonia.

Objectives: Voice therapy with semioccluded vocal tract exercises (SOVTE) has a long history of use in singers and nonsingers with dysphonia. SOVTE with increased vocal tract impedance leads to increased vocal efficiency and economy. Although there is a growing body of research on the physiological impact of SOVTE, and growing clinical sentiment about its therapeutic benefits, empirical data describing its potential efficacy in singers and nonsingers are lacking.

Activity of swallowing-related neurons in the medulla in the perfused brainstem preparation in rats.

Objectives/hypothesis: We aimed to investigate and validate the cellular activity patterns and the potential topographical organization of neurons of the medullary swallowing pattern generator (Sw-CPG). We used the perfused brainstem preparation as an innovative experimental model that allows for stable neuronal recording in the brainstem.

Study Design: Animal model.

Supportive effect of interferential current stimulation on susceptibility of swallowing in guinea pigs.

Sensory-motor control of the pharyngeal swallow requires sensory afferent inputs from the pharynx and larynx evoked by introducing bolus into the pharynx. Patients with reduced sensitivity of the pharynx and larynx are likely to have a swallowing impairment, such as pre-swallow aspiration due to delayed swallow triggering. Interferential current stimulation applied to the neck is thought to improve the swallowing function of dysphagic patients, although the mechanism underlying the facilitatory effect of such stimulation remains unknown.

An oral pharyngeal scope for objective oropharyngeal examination: a new device for oropharyngeal study.

Objective: There has been little progress in examination of the oropharynx with a light source such as electric light, a penlight, or a forehead mirror over the past 100 years. It is therefore necessary to develop methods to display and record oropharyngeal observations.

Method: Since the aim of this study was to assess the safeness to use from the perspective of physicians, medical staffs, patients, and patients' families and usefulness of pharyngeal scope, the number of devices was limited, the number of patients was not set based on hypothetical statistical tests.

Regenerative Effects of Basic Fibroblast Growth Factor on Restoration of Thyroarytenoid Muscle Atrophy Caused by Recurrent Laryngeal Nerve Transection.

Objectives: Vocal fold atrophy following unilateral vocal fold paralysis is caused by atrophy of the thyroarytenoid (TA) muscle and remains a challenge. Medialization procedures are popular treatment options; however, hoarseness often remains due to the reduction in mass or tension of the TA muscle. Therefore, in addition to medialization procedures, TA muscle reinnervation is desirable.