Lipid laden macrophage indices and reflux finding score in canine gastroesophageal reflux model

Lower esophageal sphincter augmentation by endoscopic injection of dextranomer hyaluronic acid copolymer in a porcine gastroesophageal reflux disease model

BACKGROUND

We previously demonstrated feasibility, safety, and a reproducible histologic bulking effect after injection of dextranomer hyaluronic acid copolymer (DxHA) into the gastroesophageal junction of rabbits. In the current study, we investigated the potential for DxHA to augment the lower esophageal sphincter (LES) in a porcine model of gastroesophageal reflux disease (GERD).

METHODS

Twelve Yucatan miniature pigs underwent LES manometry and 24-hour ambulatory pH monitoring at baseline, after cardiomyectomy, and 6weeks after randomization to endoscopic injection of either DxHA or saline at the LES. After necropsy, the foregut, including injection sites, was histologically examined.

RESULTS

Pigs in both groups had similar weight progression. Cardiomyectomy induced GERD in all animals, as measured by a rise in the median % of time pH <5 from 0.6 to 11.6 (p=0.02). Endoscopic injection of DxHA resulted in a higher median difference in LES length (1.8cm vs. 0.4cm, p=0.03). In comparison with saline injection, DxHA resulted in 120% increase in LES pressure, and 76% decrease in the mean duration of reflux episodes, but these results were not statistically significant. Injection of DxHA induced a foreign body reaction with fibroblasts and giant cells.

CONCLUSIONS

Porcine cardiomyectomy is a reproducible animal GERD model. Injection of DxHA may augment the LES, offering a potential therapeutic effect in GERD.

Laryngoscopy findings and histological results in a rabbit gastroesophageal reflux model

The role of lower esophageal sphincter (LES) in laryngopharyngeal reflux is controversial. In this study, we used an animal model to investigate the association between LES dysfunction and reflux laryngitis. Twelve healthy New Zealand albino rabbits (2.5-3.5 kg) were utilized in this study. The animals were divided into two groups. Eight rabbits underwent total cardiomyectomy to induce reflux, and the remaining four rabbits underwent a control sham operation. A laryngoscopy and a 24-hour intra-esophageal pH-metry were performed prior to surgery and again 2 and 8 weeks postsurgery. After the final laryngoscopy, all animals were sacrificed to obtain histological results. Total cardiomyectomy significantly increased the reflux index, the duration of the longest reflux episode and the total number of episodes that occurred in 24 h postsurgery. No significant difference was observed in the reflux finding score (RFS) between preoperative and 2-week postoperative rabbits (P = 0.11). But there was a statistically significant change in the RFS before and 8 weeks after the induction of reflux from 4.6 ± 0.9 to 8.3 ± 3.6 (P = 0.02). Submucous gland hyperplasia and inflammation were significantly increased in the reflux group compared to the control group. The results of this study suggest that chronic lower esophageal sphincter dysfunction is associated with reflux laryngitis in rabbits.

Establishment of a reflux esophago-laryngitis model in rats

BACKGROUND

To investigate the pathophysiology of reflux laryngitis, an experimental model is required.

AIM

The aim of this study is to establish an animal model of reflux esophago-laryngitis, modifying our previously reported model of chronic acid reflux esophagitis.

METHODS

The modified chronic acid reflux esophagitis (m-RE) group (n = 10), in which the duodenum was wrapped with 2.5 mm of Nelaton catheter, was not treated with any drugs. Also postoperatively, two treatment groups (n = 10 in each) received different dosages of rabeprazole (RPZ): 1.0 mg/kg/day (RPZ 1.0 group) or 10.0 mg/kg/day (RPZ 10.0 group). As a control group (n = 5), other rats underwent sham operation. The esophagus and larynx were resected on day 14 after the operation, and ulcer score of the esophagus was assessed. The epithelial thickness and leukocyte infiltration of the supraglottic and subglottic laryngeal mucosae were investigated. The number of interleukin (IL)-1β-positive cells was also counted and defined as the IL-1β labeling index.

RESULTS

In the m-RE group, the epithelial thickness, leukocyte infiltration, and IL-1β labeling index of the supraglottic and subglottic laryngeal mucosae were increased compared with controls (P < 0.01). In the RPZ groups, not only the ulcer score of esophagus but also the epithelial thickness, leukocyte infiltration, and IL-1β labeling index of both the supraglottic and subglottic laryngeal mucosae were decreased dose-dependently relative to the m-RE group (P < 0.05).

CONCLUSIONS

Our modified chronic acid reflux esophagitis model proved useful in establishing a rat reflux esophago-laryngitis model, with both pathological laryngeal findings and reflux esophagitis shown to be improved by administration of a proton pump inhibitor.

Laryngopharyngeal reflux: current concepts and questions

PURPOSE OF REVIEW

Laryngopharyngeal reflux is a widely recognized disorder. Yet, decades after its initial description, debate persists regarding pathophysiology, diagnosis, and treatment. This review addresses current literature on laryngopharyngeal reflux and identifies areas of controversy and future opportunities for research.

RECENT FINDINGS

Despite numerous research efforts, the diagnosis and treatment of laryngopharyngeal reflux remain elusive and unproven. Acid-induced changes in laryngopharyngeal mucosa have been confirmed by histologic evidence. However, the implications of this for laryngeal symptoms and signs are unclear. Diagnosis remains controversial, confounded by lack of standardization and accepted, evidence-based norms. Whereas treatment is generally believed by clinicians to be effective in alleviating symptoms and signs attributed to laryngopharyngeal reflux, incontrovertible data confirming efficacy are scarce. Confounding the issues further, there are numerous studies that purport to show that various widely used treatments are not effective, although the scientific merit of virtually all of these studies has been challenged.

SUMMARY

Laryngopharyngeal reflux remains a controversial diagnosis. Treatment with proton pump inhibitors persists despite weak evidence supporting or refuting their utility, and well designed studies are needed to understand diagnosis, treatment, pathyophysiology, and long-term health consequences of laryngopharyngeal reflux and its treatment.

The effect of surgically created gastroesophageal reflux on intrapleural pressures in dogs

The causal relationship between gastroesophageal reflux (GER) and respiratory disorders is not well understood. Previous experimental studies that investigated this relationship were performed in anesthetized animals and used artificial acidification of esophagus for simulation of GER. In this study, we investigated the impact of GER on intrapleural pressures (IPP) in conscious, unanesthetized dogs. After the induction of appropriate anesthesia, 5 purpose-bred mongrel dogs underwent reflux-creating surgery (partial cardiomyectomy). The presence of GER was confirmed by determining the reflux index (RI) and the duration of longest reflux episode (DLRE) after 24-h intraesophageal pH-metry. IP was monitored before and after cardiomyectomy using a subcutaneously placed telemetric implant with its pressure-sensor catheter tip inserted into the pleural space. Partial cardiomyectomy resulted in a significant increase in RI from a preoperative mean value of 0.38 +/- 0.21 to 7.52 +/- 2.56%, and DLRE from 1.22 +/- 1.12 to 36.80 +/- 12.71 min, as recorded by the proximal sensor of the pH probe. A similar trend was observed at the distal sensor. After cardiomyectomy, the negative inspiratory IPP significantly increased from 17.2 +/- 7.9 to 28.4 +/- 9.7 mm Hg. A similar effect was observed in the negative expiratory IPP. The negative inspiratory IPP had a significant correlation with both RI (R = 0.932) and DLRE (R = 0.899). Cardiomyectomy causes GER, the severity of which correlates with negative inspiratory IPP in a dog model. The suggested model allows for the investigation of the pathologic association of GER with respiratory disorders in conscious animals.