Acute inflammatory response to contrast agent aspiration and its mechanisms in the rat lung.

Objectives/hypothesisContrast agent (CA) aspiration is an established complication of upper gastrointestinal and videofluoroscopic swallow studies. The underlying molecular biological mechanisms of acute response to CA aspiration in the respiratory organs remain unclear. The aims of this study were to elucidate the histological and biological influences of three kinds of CAs on the lung and to clarify the differences in acute responses.Study designAnimal model.MethodsEight-week-old male Sprague Dawley rats were divided into five groups (n = 6 in each group). Three groups underwent tracheal instillation of one of three different CAs: barium (Ba) sulfate, nonionic contrast agents (NICAs), and ionic contrast agents (ICAs). A control group was instilled with saline and a sham group was instilled with air. All animals were euthanized on day 2 after treatment and histological and gene analysis was performed.ResultsNo animal died after CA or control/sham aspiration. Ba caused severe histopathologic changes and more prominent inflammatory cell infiltration in the lungs compared with the two other iodinated contrast agents. Increases in expressions of inflammatory cytokines (tumor necrosis factor [Tnf], interleukin-1β [Il1b], and interferon-γ [Ifng]) were observed in Ba aspiration rats, and upregulation of Il1b was seen in ICA aspiration rats. NICA did not cause obvious histologic changes or expressions of inflammatory cytokines and fibrosis-related genes in the lungs.ConclusionsBa caused significantly more acute lung inflammation in a rodent model than did ioinic and nonionic iodinated CAs. Nonionic contrast did not cause any discernible inflammatory response in the lungs, suggesting that it may be the safest contrast for videofluoroscopic swallow studies.Level of evidenceNA Laryngoscope, 129:1533-1538, 2019

Effects of early local administration of high-dose bFGF on a recurrent laryngeal nerve injury model

Abstract Background Research on regenerative medicine using basic fibroblast growth factor (bFGF) has recently advanced in the field of laryngology. We previously reported that local administration of bFGF 1 month after recurrent laryngeal nerve (RLN) paralysis compensated for atrophy of the thyroarytenoid muscle. The objective of this study was to elucidate the effects of early bFGF administration on the thyroarytenoid muscle after RLN transection and to investigate the underlying mechanisms. Methods A rat model of RLN paralysis was established in this study. One day after RLN transection, low- (200 ng) or high-dose (2000 ng) bFGF or saline (control) was administered to the thyroarytenoid muscle. The larynges were excised for histological and immunohistochemical examinations at 1, 7, 14, 28, and 56 days after administration. Results The cross-sectional thyroarytenoid muscle area was significantly larger in the high-dose group than in the saline and low-dose groups on days 28 and 56. Immunohistochemistry indicated that bFGF significantly increased the number of satellite cells in the thyroarytenoid muscle up to day 14 and that of neuromuscular junctions on days 28 and 56. Conclusions A single, early local administration of high-dose bFGF prevented atrophic changes in the thyroarytenoid muscles by activating satellite cell proliferation and reforming neuromuscular junctions. As increased neuromuscular junctions are expected to maintain myofiber volume, bFGF administration may prevent thyroarytenoid muscle atrophy in the mid to long term. Graphical abstrac

Aspiration prevention surgeries: a review

Abstract Background Severe dysphagia can cause intractable pneumonia and lead to life-threatening conditions. Intractable aspiration can occur despite medical management for aspiration prevention. Surgical intervention is indicated for intractable aspiration to prevent potentially life-threatening complications. Since the 1970s, several surgical treatments to prevent aspiration have been reported, and various aspiration prevention surgeries have been introduced, but little is known about them or their benefits. This is a review of the types of aspiration prevention surgery, with the aim of increasing aspiration prevention surgery awareness and their clinical outcomes among medical professionals, which will guide the choices of aspiration prevention surgeries for patients with intractable aspiration. Main body Aspiration prevention surgeries can be categorized into three according to their approaches: removal of the larynx, altering the structure of the trachea, and closure of the larynx. Aspiration prevention surgeries to remove the larynx include total and central-part laryngectomy. Aspiration prevention surgeries to alter the structure of the trachea include tracheoesophageal diversion, laryngotracheal separation, and the tracheal flap method. Surgeries to close the larynx can be divided into supraglottic laryngeal closure, glottic laryngeal closure, and subglottic laryngeal closure. Aspiration prevention surgeries prevent aspiration and increase oral intake in 50–80% of patients. Most patients lose vocal function after aspiration prevention surgeries; however, some patients who have undergone total laryngectomy or laryngotracheal separation restored their speech function through tracheoesophageal puncture and use of voice prosthesis. Postoperative suture failure is frequent after epiglottic flap closure and total laryngectomy but rare after central-part laryngectomy, laryngotracheal separation, glottic closure, and subglottic closure. Furthermore, aspiration prevention surgeries improve the quality of life of patients and their caregivers by decreasing suctioning frequency. Conclusions In this review, we described the history and development of aspiration prevention surgeries. Medical professionals need to continually improve their knowledge and skills to facilitate appropriate aspiration prevention surgeries according to patient condition

Acute inflammatory response to contrast agent aspiration and its mechanisms in the rat lung.

Objectives/hypothesisContrast agent (CA) aspiration is an established complication of upper gastrointestinal and videofluoroscopic swallow studies. The underlying molecular biological mechanisms of acute response to CA aspiration in the respiratory organs remain unclear. The aims of this study were to elucidate the histological and biological influences of three kinds of CAs on the lung and to clarify the differences in acute responses.Study designAnimal model.MethodsEight-week-old male Sprague Dawley rats were divided into five groups (n = 6 in each group). Three groups underwent tracheal instillation of one of three different CAs: barium (Ba) sulfate, nonionic contrast agents (NICAs), and ionic contrast agents (ICAs). A control group was instilled with saline and a sham group was instilled with air. All animals were euthanized on day 2 after treatment and histological and gene analysis was performed.ResultsNo animal died after CA or control/sham aspiration. Ba caused severe histopathologic changes and more prominent inflammatory cell infiltration in the lungs compared with the two other iodinated contrast agents. Increases in expressions of inflammatory cytokines (tumor necrosis factor [Tnf], interleukin-1β [Il1b], and interferon-γ [Ifng]) were observed in Ba aspiration rats, and upregulation of Il1b was seen in ICA aspiration rats. NICA did not cause obvious histologic changes or expressions of inflammatory cytokines and fibrosis-related genes in the lungs.ConclusionsBa caused significantly more acute lung inflammation in a rodent model than did ioinic and nonionic iodinated CAs. Nonionic contrast did not cause any discernible inflammatory response in the lungs, suggesting that it may be the safest contrast for videofluoroscopic swallow studies.Level of evidenceNA Laryngoscope, 129:1533-1538, 2019

Chronic inflammatory response in the rat lung to commonly used contrast agents for videofluoroscopy.

ObjectivesContrast agents (CAs) are essential for upper gastrointestinal and videofluoroscopic swallow studies (VFSSs). Recently, we reported that small amounts of Ba aspiration caused severe acute lung inflammation in a rodent model. However, the underlying molecular biological mechanisms of chronic response to CA aspiration remain unclear. The aims of this study were to explore the underlying molecular biological mechanisms of the chronic response to three kinds of CA aspiration on the lung.Study designAnimal model.MethodsEight-week-old male Sprague Dawley rats were divided into five groups (n = 6, each group). Three groups underwent tracheal instillation of one of three CAs: barium sulfate (Ba), ionic iodinated contrast agent (ICA), and nonionic iodinated contrast agent (NICA). A sham group was instilled with air and a control group was instilled with saline. All animals were euthanized 30 days after treatment and histological and gene analyses were performed.ResultsNo animal died after CA or sham/control aspiration. Ba particles remained after 30 days and caused histopathologic changes and inflammatory cell infiltration. Iodinated ICA and NICA did not result in perceptible histologic change. Expression of Tnf, an inflammatory cytokine was increased in only Ba aspirated rats (P = .0076). Other inflammatory cytokines and fibrosis-related genes did not alter between groups.ConclusionAspirated Ba particles did not clear from the lung within a month and caused mild chronic pulmonary inflammation. ICA and NICA did not cause any inflammatory responses in the lungs, suggesting that ICA and NICA may be safer CAs for VFSS than Ba.Level of evidenceNA