Animal model of otitis media with effusion

Glycerospanlastics: State-of-the-art two-in-one nano-vesicles for boosting ear drug delivery in otitis media treatment

The purpose of this research was to design innovative nanovesicles for ototopical conveyance of triamcinolone acetonide (TA) for otitis media (OM) treatment via incorporating glycerol into nanospanlastics to be termed "Glycerospanlastics". The glycerospanlastics were formulated employing ethanol injection procedure, and central composite design (CCD) was harnessed for optimization of the vesicles. Various attributes of the nanovesicles, viz. particle size distribution, surface charge, TA entrapment efficiency, morphology as well as ex-vivo permeation across the tympanic membrane (TM) were characterized. In vivo implementation of the optimized glycerospanlastics loaded with TA was appraised in OM-induced rats via histopathological and biochemical measurements of the tumor necrosis factor-α (TNF-α) and Interleukin-1β (IL-1β) levels in ear homogenates. The safety and tolerability of optimized TA glycerospanlastics was also investigated in non-OM induced animals. The results demonstrated that the optimized TA-glycerospanlastics were in a nanometer range (around 200 nm) with negative charges, high TA entrapment (>85%), good storage properties and better TM permeation relative to TA suspension. More importantly, TA-glycerospanlastics performed better than marketed drug suspension in OM treatment as manifested by restoration of histopathological alterations in TM and lowered values of IL-1β and TNF-α. Glycerospanlastics could be promising safe ototopical nanoplatforms for OM treatment and other middle ear disorders.

Development of a rat model of patulous eustachian tube by mandibular nerve resection

OBJECTIVE

Patulous eustachian tube (PET) is currently treated using a variety of conservative or surgical approaches. To further elucidate the pathology of PET and to establish new therapies, the development of an animal model is necessary. The objective of this study was to develop a highly reproducible and sustainable rat model of PET by mandibular nerve resection.

METHODS

Sixteen rats underwent mandibular nerve resection. Following an external incision, the main trunk of the mandibular nerve at the foramen ovale was identified in the pterygoid fossa, and its branches were resected. This surgery was performed on the right side, with the unoperated left side used as the control. To determine eustachian tube (ET) function, passive opening pressure (POP) was measured using inflation method up to Week 16 post-surgery. Changes in POP were statistically compared to the preoperative level on the operated and control sides. In addition, specimens of the ET and its surrounding tissue at Week 16 post-surgery were prepared for morphological evaluation in eight rats.

RESULTS

On the control side, POP did not significantly decrease across the 16 weeks post-surgery compared to the preoperative level. In contrast, on the operated side, POP was significantly decreased at Week 2 and continued to be lower than the preoperative level until at least Week 16 post-surgery. POP dropped 10% or more on the operated side examined in thirteen rats. Histologically, the medial pterygoid muscle was atrophied on the operated side mainly.

CONCLUSION

Mandibular nerve resection in rats may be an effective method for generating an animal model of PET. It was suggested that this rat model may be useful for verifying new treatments for PET.

The association of middle ear effusion with trigeminal nerve mass lesions in dogs

The trigeminal nerve is involved in the opening of the pharyngeal orifice of the Eustachian tube by operating the tensor veli palatini muscle. The hypothesis was investigated that middle ear effusion occurs in a more severe disease phenotype of canine trigeminal nerve mass lesions compared with dogs without middle ear effusion. Three observers reviewed canine MRIs with an MRI-diagnosis of trigeminal nerve mass lesion from three institutions. Various parameters describing the musculature innervated by the trigeminal nerve were scored and compared between dogs with and without middle ear effusion. Nineteen dogs met the inclusion criteria. Ipsilateral middle ear effusion was observed in 63 per cent (95% CI 48.4 per cent to 77.6 per cent) of the dogs. The size of the trigeminal nerve mass lesions was positively correlated with the severity of masticatory muscle mass loss (Spearman r=0.5, P=0.03). Dogs with middle ear effusion had a significantly increased generalised masticatory muscle mass loss (P=0.02) or tensor veli palatini muscle loss score (P=0.03) compared with those without. Larger trigeminal nerve mass lesions were associated with a greater degree of masticatory muscle mass loss. Masticatory muscle mass and, importantly, tensor veli palatini muscle mass was more severely affected in dogs with middle ear effusion suggesting an associated Eustachian tube dysfunction.

Can chronic nasal obstruction cause dysfunction of the paratubal muscles and otitis media? An experimental study in developing Wistar rats

OBJECTIVE

To quantitatively analyze modifications of the paratubal muscles in developing Wistar rats following nasal obstruction.

MATERIAL AND METHODS

Twenty-four Wistar rats were used. Twelve were examined at 6, 8 and 12 weeks after birth and were considered normal controls. The nostrils of the remaining 12 rats were bilaterally obstructed by means of a synthetic resin 28 days after birth. The animals were sacrificed at either 2, 4 or 8 weeks after nostril occlusion. Serial sections were made in the dorsoventral plane and stained with hematoxylin-eosin. Four 5 x 5 microm2 areas, selected within the paratubal muscles, were histologically analyzed and the number of muscular fibers was counted manually.

RESULTS

The number of tensor veli palatini muscle fibers progressively decreased in the obstructed rats compared with age-matched normal controls and in those that had been obstructed for 4 and 8 weeks these reductions were statistically significant.

CONCLUSION

The correct development of the paratubal muscles seems to be linked to physiological nasal breathing and is negatively affected by oral breathing.