pH-sensitive polymeric nanoparticles with antioxidant and anti-inflammatory properties against cisplatin-induced hearing loss.

Polymeric nanoparticles (NPs) based on smart synthetic amphiphilic copolymers are used to transport and controlled release dexamethasone in the inner ear to protect against the ototoxic effect of cisplatin. The NPs were based on a mixture of two pseudo-block polymer drugs obtained by free radical polymerization: poly(VI-co-HEI) and poly(VP-co-MVE) or poly(VP-co-MTOS), being VI 1-vinylimidazole, VP N-vinylpyrrolidone, and HEI, MVE and MTOS the methacrylic derivatives of ibuprofen, α-tocopherol and α-tocopheryl succinate, respectively. The NPs were obtained by nanoprecipitation with appropriate hydrodynamic properties, and isoelectric points that matched the pH of inflamed tissue. The NPs were tested both in vitro (using HEI-OC1 cells) and in vivo (using a murine model) with good results. Although the concentration of dexamethasone administered in the NPs is around two orders of magnitude lower that the conventional treatment for intratympanic administration, the NPs protected from the cytotoxic effect of cisplatin when the combination of the appropriate properties in terms of size, zeta potential, encapsulation efficiency and isoelectric point were achieved. To the best of our knowledge this is the first time that pH sensitive NPs are used to protect from cisplatin-induced hearing loss by intratympanic administration.

Spontaneous Cannabinoid Receptor 2 (CB2) Expression in the Cochlea of Adult Albino Rat and Its Up-Regulation after Cisplatin Treatment.

We provide evidence for the presence of cannabinoid CB2 receptors in some cellular types of the cochlea of the adult albino rat. Cannabinoids and their receptors are increasingly being studied because of their high potential for clinical use. As a hyperspecialized portion of the peripheral nervous system, study of the expression and function of cannabinoid receptors in the hearing organ is of high interest. Stria vascularis and inner hair cells express CB2 receptor, as well as neurites and cell bodies of the spiral ganglion. Cellular types such as supporting cells and outer hair cells, in which the expression of other types of functional receptors has been reported, do not significantly express CB2 receptors in this study. An up-regulation of CB2 gene expression was detected after an ototoxic event such as cisplatin treatment, probably due to pro-inflammatory events triggered by the drug. That fact suggests promising potential of CB2 receptor as a therapeutic target for new treatments to palliate cisplatin-induced hearing loss and other ototoxic events which triggers inflammatory pathways.

Otoprotective properties of 6α-methylprednisolone-loaded nanoparticles against cisplatin: In vitro and in vivo correlation.

6α-Methylprednisolone-loaded surfactant-free nanoparticles have been developed to palliate cisplatin ototoxicity. Nanoparticles were based on two different amphiphilic pseudo-block copolymers obtained by free radical polymerization and based on N-vinyl pyrrolidone and a methacrylic derivative of α-tocopheryl succinate or α-tocopherol. Copolymers formed spherical nanoparticles by nanoprecipitation in aqueous media that were able to encapsulate 6α-methylprednisolone in their inner core. The obtained nanovehicles were tested in vitro using HEI-OC1 cells and in vivo in a murine model. Unloaded nanoparticles were not able to significantly reduce the cisplatin ototoxicity. Loaded nanoparticles reduced cisplatin-ototoxicity in vitro being more active those based on the methacrylic derivative of vitamin E, due to their higher encapsulation efficiency. This formulation was able to protect hair cells in the base of the cochlea, having a positive effect in the highest frequencies tested in a murine model. A good correlation between the in vitro and the in vivo experiments was found. FROM THE CLINICAL EDITOR: Cisplatin is a commonly used chemotherapeutic agent against many cancers clinically. However, one of the significant side-effects remains ototoxicity. Here, the authors presented their data on using 6α-methylprednisolone-loaded nanoparticles in the reduction of ototoxicity in in-vitro and in-vivo experiments. Early promising results should enable further refinement of adopting this new approach in future experiments.

Noncholesteatomatous Cyst of the Tympanic Membrane: A Nonpublished Entity?

Introduction. The presence of a serous cyst in the tympanic membrane implies the description of a new or unpublished entity based on our knowledge whose origin may be very unlikely explained on actual embryologic and anatomic background. Clinical Case. We present a case of a 45-year-old woman with progressing right hearing loss. Physical examination revealed a whitish, round-shaped malformation in the posterior-inferior quadrant of the right tympanic membrane. The cyst was removed with a transcanal tympanoplasty. Discussion. A thorough PubMed search that involved the terms tympanic membrane gland, epithelial inclusion cysts, mucous-secreting cyst, and tympanic cyst has shown no positive results. The first description of an unknown entity, such as a tympanic membrane serous cyst, may be the key for clinicians to start paying attention to patients who suffer from similar pathologies and may pass unnoticed because of their rarity or peculiarity.

Review of the biologic agents used for immune-mediated inner ear disease.

INTRODUCTION AND OBJECTIVES: Immune-mediated inner ear disease (IMIED) is one of the few reversible forms of sensorineural hearing loss. Treatment is based on high-dose corticosteroids, although long-term therapy is associated with serious adverse effects; this has led to the use of other agents or different routes of administration such as transtympanic delivery. This study analyses the role of biological agents in IMIED management. MATERIAL AND METHODS: We searched PUBMED for studies that examined the response to treatment with different biological agents in patients with IMIED. The following data were extracted from the selected studies and entered into a standardised database: exclusion and inclusion criteria, characteristics of the patients studied, treatment, outcome measures and response rates achieved. RESULTS: Thirteen studies were included in this review. A TNF alpha inhibitor (etanercept, infliximab, adalimumab) was used in 8 studies, an IL-1 antagonist (anakinra) was used in 3 studies and rituximab, an antibody directed against the CD20 surface antigen on B lymphocytes, was evaluated in 2 studies. Most studies achieved a hearing improvement or stabilisation in more than 70% of treated patients. CONCLUSIONS: Biological agents can play a role in the management of patients with IMIED, at least in those patients who do not respond to conventional therapy or whose hearing is not stabilised. However, specially-designed randomised controlled clinical trials are needed to assess their effectiveness.

Reactive oxygen species in apoptosis induced by cisplatin: review of physiopathological mechanisms in animal models.

Cisplatin is a highly effective chemotherapeutic agent but displays significant ototoxic side effects. The most prominent change seen in the cochlea after cisplatin administration consists of loss of outer hair cells. Several mechanisms are believed to mediate cisplatin-induced apoptosis: binding of cisplatin to guanine bases on DNA and the formation of inter- and intra-strand chain cross-linking, generation of reactive oxygen species (ROS) with increased lipid peroxidation and Ca(2+) influx and, finally, inflammation mediated by cisplatin. The aim of the present review is to analyze the role of ROS in the mechanisms causing cisplatin-mediated apoptosis in the inner ear and the contribution of the different pathways involved, emphasizing the main strategies to blockade events leading to apoptosis of cochlear cells.

Endogenous protection against oxidative stress caused by cisplatin: role of superoxide dismutase.

CONCLUSION: The administration of cisplatin induces the activation of superoxide dismutase (SOD) as a response to oxidative stress in the cochleae of Sprague-Dawley rats and this activation is proportional to the activation of the intrinsic pathway of apoptosis. OBJECTIVES: To determine the role of the antioxidant endogenous mechanism in the preservation of cochlear integrity and function in an experimental model of cisplatin ototoxicity. METHODS: Sixteen Sprague-Dawley rats were studied at 7 days after intraperitoneal injection of CDDP (n = 8) or 10 ml/kg NaCl 0.9% w/v in the control group (n = 8) by means of auditory steady-state responses. These findings were compared with the expression of SOD and caspase-3/7 and caspase-9 activities. RESULTS: Groups receiving cisplatin showed increased auditory thresholds after injection of cisplatin and control groups maintained normal hearing. Measurements of caspase-3/7 and caspase-9 showed a significant increase in cisplatin-treated rats. A significantly increased activity of total SOD in whole cochlear extracts was observed in animals from the CDDP groups vs control animals. Likewise, differences between CDDP groups were also statistically significant.

[Radiological diagnostic of the non-pathological conditions of the petrous apex]. / Diagnóstico radiológico de las condiciones no patológicas del ápex petroso.

Many patients with otological symptoms are remitted to the otolaryngology outpatient clinics every day. These patients commonly undergo imaging studies, generally magnetic resonance imaging (MRI). In some cases, a positive unilateral result is found in the form of a potentially pathological signal that can be observed in the petrous apex region. We present the cases of 6 patients (aged between 26 and 62 years) with asymmetric bone marrow distribution or trapped mucous fluid secretions in the petrous apex, collected over a 6-year period. Diagnosis was made with the use of CT scans and MRI. All of the patients were referred for skull base surgery. In all cases a non-pathologic asymmetry was diagnosed in the petrous apex. Certain non-pathologic conditions of the petrous apex must be treated expectantly without any surgery.

[Ultra-structural study of the lateral portion of the auditory sensorial organ using a decalcification-free method]. / Estudio ultraestructural de la porción lateral del órgano sensorial auditivo mediante un método sin descalcificación.

OBJECTIVE: To explain the development of a new personal technique to study the spiral ligament and stria vascularis in Guinea pig cochleae by obtaining sample tissue without decalcification and to assess its validity for electron microscopy analysis. MATERIAL AND METHOD: Samples were taken from five female Guinea pigs weighing 200-250 g and were fixed in glutaraldehyde and paraformaldehyde for analysis of the spiral ligament and stria vascularis ultrastructure by transmission electron microscopy. RESULTS: All of the ultrastructure components in the spiral ligament and stria vascularis could be examined without the need for decalcification. CONCLUSIONS: Our method to obtain and analyze samples of cochlea side wall is valid, easy and faster.

Adverse effects of glucocorticoid therapy for inner ear disorders.

BACKGROUND: Because of their anti-inflammatory effects and suppression of the immune system, glucocorticoids have been widely used in otolaryngologic disorders and perioperative conditions. OBJECTIVE: The objective of the present study was to determine the incidence of adverse effects after the administration of glucocorticosteroids in patients affected by diverse inner ear disorders. METHODS: One hundred and sixty-three patients affected by sudden sensorineural hearing loss, 39 with progressive sensorineural hearing loss and 16 with fluctuating sensorineural hearing loss were subjected to glucocorticosteroid therapy with 6-methylprednisolone at a starting dose of 1 mg/kg body weight per day; this therapy was tapered during the next 21-28 days. In 20 patients with profound hearing loss (>70 dB), 3 boluses of prednisolone-21-hydrogen-succinate (500 mg per day) were administered. After receiving the boluses, these patients continued with the oral 6-methylprednisolone scheme. RESULTS: Mild adverse effects were observed in 16 patients (7.01%). Only 2 patients (0.9%) with sudden sensorineural hearing loss showed severe complications: peptic ulcer and avascular necrosis of the femoral heads. CONCLUSIONS: The low percentage of severe adverse effects observed in the present study validates the use of corticosteroids for the treatment of inner ear disorders although we should not underestimate these rare complications.

Does the serological study for viral infection in autoimmune inner ear disease make sense?

Viral infections of the labyrinth have been considered a major source of auditory and vestibular system pathology. However, the involvement of virus in the development of immune reactions responsible for immunomediated inner ear disease has not been studied enough. Following viral infection, an effector immune response, humoral (B cell) and/or cytotoxic (T cell) is directed against a virus and it might cross-react with self-protein or autoantigen, evoking an autoimmune response. Since clinically it can be very difficult to establish a viral etiology for such disorders, serologic studies can be used to confirm the suspected diagnosis. Patients affected by immunomediated inner ear disease that had presented an upper respiratory tract infection underwent an immunologic workup study including microbiological study. After the application of this diagnostic protocol, only one patient, that was subsequently diagnosed with Cogan's syndrome, showed a positive serological test for viral infection. On the basis of the low efficacy of serological testing and due to the lack of evidence, we do not recommend to carry out serologic studies for viral infection.

[Environmental scanning electron microscopy for biofilm detection in tonsils]. / Microscopia electrónica de barrido ambiental para la detección de biopelículas en las amígdalas.

INTRODUCTION AND OBJECTIVE: To describe an environmental scanning electron microscopic method for the study of biofilms in clinical samples. A comparison with standard scanning electron microscopy is performed. PATIENTS AND METHOD: Nine patients with a past history of recurrent tonsillitis underwent tonsillectomy. Samples from each patient were obtained for both conventional and environmental scanning electron microscopy. The tonsils removed from 2 patients with sleep apnoea syndrome were used as controls. RESULTS: Eight of nine tonsils had biofilms on their surface. Scanning electron microscopy showed accumulations of bacteria covered by fibrillar structures resulting from the sample dehydration process. Environmental scanning electron microscopy provided a view of bacteria embedded in a homogeneous, amorphous substance that was preserved during the examination. CONCLUSIONS: Environmental scanning electron microscopy permits the imaging of wet systems at different degrees of dehydration. It therefore allows researchers to observe biofilms in their natural hydrated state.

Morphological sequence of Plastipore extrusion in experimental otitis media.

OBJECTIVES: Plastipore prostheses are still used by many surgeons, although the functional results are controversial. The aim of this study was the morphological analysis of Plastipore material performance in the middle ear of rats, with special attention to extrusion. METHODS: Twenty-four Wistar rats were given implants made of commercially available Plastipore and assigned to 3 groups: group A, with implantation in a healthy middle ear; group B, with implantation and cauterization of the nasopharyngeal orifice of the eustachian tube (hypoventilation); and group C, with implantation, cauterization of the eustachian tube, and bacterial inoculation with Pseudomonas aeruginosa. RESULTS: The pathological study showed in nearly all cases the disintegration of the biomaterial. Adhesion between the biomaterial and bone could be seen in 1 rat from group C (hypoventilation and infection). In group C, the Plastipore was in contact with the tympanic membrane in 1 case and was extruding in 2 animals. Different phases of extrusion were defined. No extrusion was observed in the other groups. CONCLUSIONS: The sequential stages of Plastipore extrusion are demonstrated. Infection seems to be the most important factor in Plastipore extrusion in our model.

Evolution of middle ear changes after permanent eustachian tube blockage.

OBJECTIVE: To develop a valid animal model for otitis media with effusion (OME). DESIGN: Forty specific pathogen-free Wistar rats underwent a procedure based on the permanent obstruction of pharyngeal eustachian tube by means of electrocoagulation without any manipulation. SETTING: Ear Research Group, Department of Otorhinolaryngology, Puerta de Hierro Hospital, Universidad Autonoma de Madrid, Madrid, Spain. MAIN OUTCOME MEASURES: The assessment of OME by otoscopy and tympanometry. The rats were humanely killed at 15 and 90 days, and temporal bones were obtained and processed for histopathologic study. RESULTS: The histopathologic study of the temporal bones demonstrated the occurrence of chronic effusion and mucosal changes owing to mucoperiosteal enlargement. CONCLUSIONS: Comparison with other experimental models was made. Our animal model was consistent and reproducible and resembled human OME.

[Autoimmune hearing loss: improving diagnostic performance]. / Sordera autoinmunitaria: mejorando el rendimiento de su diagnóstico.

OBJECTIVES: Due to the lack of specific serological markers for the diagnosis of immune-mediated hearing loss, an exhaustive immunologic work-up study for patients is usually performed. The aim of the present study is to find the most cost-effective laboratory tests used for the diagnosis of this entity. PATIENTS AND METHOD: Comparative study between 2 groups of patients with a high suspicion of suffering diverse clinical forms of immune-mediated hearing loss, subjected to different serologic testing designs: the classical immunologic work-up study (125 patients) in comparison with a more restricted examination analysis (57 patients), based on a high risk profile recently reported. RESULTS: Diagnostic efficiency was similar. CONCLUSIONS: Since financial resources are limited, ANA and immunophenotype of PBL (peripheral blood lymphocytes) are recommended for the evaluation of a patient with suspected immune-mediated hearing loss.

Tissular changes induced by Pseudomonas aeruginosa in an otitis media rat model with tubal obstruction.

CONCLUSIONS: This is a suitable model for the study of different features of middle ear inflammation. This model allows manipulations inside the middle ear while preserving relevant structures such as the tympanic membrane, and provides a useful model for the study of interactions between bacterial infection and eustachian tube dysfunction. OBJECTIVES: Analysis of early and late histological features in an experimental model of Pseudomonas aeruginosa middle ear inoculation in the rat designed for the study of middle ear procedures. MATERIALS AND METHODS: Thirty Wistar rats were inoculated with Pseudomonas aeruginosa in the tympanic bulla followed by the cauterization of the eustachian tube. Culturing of middle ear effusion was carried out at 7 days follow-up and at sacrifice. Processing of the temporal bones for light microscopy was performed at 7, 14, 30 and 60 days. RESULTS: Early cultures were positive in most cases, thus proving that middle ear inflammation was due to the presence of inoculated Pseudomona aeruginosa. Mucoperiosteal inflammatory changes similar to those observed in human middle ear infection were seen. Acute inflammatory cell infiltration was seen at 7 and 14 days, gradually decreasing to chronic inflammatory changes with fibroplasia at 60 days. Bone resorption was observed at 7 and 14 days, changing to a bony deposition at 30 and 60 days.

Spontaneous otitis media in Wistar rats: an overlooked pathology in otological research.

The rat is commonly employed in otological research, but spontaneous ear infections can confound the results of experimental procedures--wasting time, money, and animals. The authors focus on the incidence of spontaneous otitis media in Wistar rats. They compare disease incidence in animals housed in standard cages with those housed in barrier units, showing that 20% of their conventionally housed animals developed spontaneous otitis media, whereas only 5% of their animals housed in isolated units were infected. These results underscore the importance of strict control of the shipping, housing conditions, and manipulation of animals to be used in otological research.