RESUMEN

Abstract Introduction: The use of electron microscopy in the study of the inner ear has allowed us to observe minute details of the hair cells, especially in ototoxicity studies; however, the preparation of this material is a difficult and delicate task. In an attempt to simplify the handling of these materials, two agents, toluidine blue and ethylenediamine tetra-acetic acid were tested, in addition to the elimination of osmium tetroxide during the preparation of albino guinea pig cochleae. We also tested the applicability of these methodologies in an ototoxicity protocol. Objective: To verify the quality of the images obtained with and without the use of ethylenediamine tetra-acetic acid, toluidine blue and osmium tetroxide in the preparation of cochleae of albino guinea pigs for the scanning electron microscopy. Methods: Three groups of cochleae were used. In Group 1, 10 cochleae were prepared with the usual methodology, dissecting the optical capsule without decalcification and using osmium tetroxide as a post-fixative agent. In Group 2, we prepared 10 cochleae decalcified with ethylenediamine tetra-acetic acid, injecting toluidine blue in the endolymphatic space to facilitate the identification of the organ of Corti. In Group 3, we used 4 cochleae of guinea pigs that received 3 doses of cisplatin (7.5 mg/kg, D1-D5-D6), two prepared according to the methodology used in Group 1 and two with that used in Group 2. Scanning electron microscopy images were obtained from the organ of Corti region of the basal turn of each cochlea. Results: The organ of Corti was more easily identified with the use of toluidine blue. The dissection of the cochlea was more accurate in the decalcified cochleae. The quality of the images and the preservation of the organ of Corti obtained with the two methodologies were similar. Conclusion: The proposed modifications resulted in images of similar quality as those observed using the traditional methodology.

Resumo Introdução: O emprego da microscopia eletrônica no estudo da orelha interna permitiu observar detalhes minuciosos das células ciliadas especialmente em estudos de ototoxicidade. Entretanto, o preparo desse material é trabalhoso e delicado. Para simplificar a manipulação desses materiais, testou-se o uso de dois agentes, azul de toluidina e ácido etilenodiamino tetra-acético, além da retirada do tetróxido de ósmio na preparação de cócleas de cobaias albinas. Testamos também a aplicabilidade dessas metodologias em um protocolo de ototoxicidade. Objetivo: Verificar a qualidade das imagens obtidas com e sem o uso de ácido etilenodiamino tetra-acético, azul de toluidina e tetróxido de ósmio na preparação de cócleas de cobaias albinas para a microscopia eletrônica de varredura. Método: Foram utilizados três grupos de cócleas. No Grupo 1 preparou-se 10 cócleas com a metodologia usual, dissecando a cápsula ótica sem descalcificac¸ão e utilizando tetróxido de ósmio como pós-fixador. No Grupo 2 preparamos 10 cócleas descalcificadas com ácido etilenodiamino tetra-acético, injetando azul de toluidina no espac¸o endolinfático para facilitar a identificação do órgão de Corti. No Grupo 3 utilizamos 4 cócleas de cobaias que receberam 3 doses de cisplatina (7,5 mg/kg, D1-D5-D6), duas preparadas com a metodologia do Grupo 1 e duas com a do Grupo 2. Foram obtidas imagens da microscopia eletrônica de varredura da região do órgão de Corti do giro basal de cada cóclea. Resultados: O órgão de Corti foi mais facilmente identificado com o azul de touidina. A dissecção da cóclea foi mais precisa nas cócleas descalcificadas A qualidade das imagens e a preservac¸ão do órgão de Corti obtidas com as duas metodologias foi similar. Conclusão: As modificações propostas resultaram em imagens de qualidade similar as observadas com o uso da metodologia tradicional.

Asunto(s)

RESUMEN

INTRODUCTION: The use of electron microscopy in the study of the inner ear has allowed us to observe minute details of the hair cells, especially in ototoxicity studies; however, the preparation of this material is a difficult and delicate task. In an attempt to simplify the handling of these materials, two agents, toluidine blue and ethylenediamine tetra-acetic acid were tested, in addition to the elimination of osmium tetroxide during the preparation of albino guinea pig cochleae. We also tested the applicability of these methodologies in an ototoxicity protocol. OBJECTIVE: To verify the quality of the images obtained with and without the use of ethylenediamine tetra-acetic acid, toluidine blue and osmium tetroxide in the preparation of cochleae of albino guinea pigs for the scanning electron microscopy. METHODS: Three groups of cochleae were used. In Group 1, 10 cochleae were prepared with the usual methodology, dissecting the optical capsule without decalcification and using osmium tetroxide as a post-fixative agent. In Group 2, we prepared 10 cochleae decalcified with ethylenediamine tetra-acetic acid, injecting toluidine blue in the endolymphatic space to facilitate the identification of the organ of Corti. In Group 3, we used 4 cochleae of guinea pigs that received 3 doses of cisplatin (7.5mg/kg, D1-D5-D6), two prepared according to the methodology used in Group 1 and two with that used in Group 2. Scanning electron microscopy images were obtained from the organ of Corti region of the basal turn of each cochlea. RESULTS: The organ of Corti was more easily identified with the use of toluidine blue. The dissection of the cochlea was more accurate in the decalcified cochleae. The quality of the images and the preservation of the organ of Corti obtained with the two methodologies were similar. CONCLUSION: The proposed modifications resulted in images of similar quality as those observed using the traditional methodology.

Asunto(s)

RESUMEN

UNLABELLED: Radiation can cause damage to the inner ear, from a simple hearing loss all the way to profound deafness. Amifostine is a cytoprotective substance extensively used during radio-chemotherapy for malignant tumors. AIM: the objective of the present investigation was to establish the antioxidant and radioprotective effects of amifostine on the organ of Corti of albino guinea pigs irradiated in the head and neck region. MATERIALS AND METHODS: An experimental study conducted on four groups of guinea pigs were used; One group received only amifostine, one group was submitted to a single dose of 350 cGy and the other two were similarly irradiated but received amifostine doses of 100 or 200 mg/kg. All animals were slaughtered 30 days after the experiment, their bullae were removed and the damaged outer hair cells were counted. RESULT: The extent of injury was lower in the outer hair cells of the two groups treated with amifostine compared to the group that was only irradiated. There was no difference between the group treated with 100 and 200 mg/kg of amifostine. The group that received only amifostine had no cochlear damage. CONCLUSION: Amifostine is an effective cytoprotective substance in the Organ of Corti of irradiated guinea pigs.

Asunto(s)

RESUMEN

Radiation can cause damage to the inner ear, from a simple hearing loss all the way to profound deafness. Amifostine is a cytoprotective substance extensively used during radio-chemotherapy for malignant tumors. AIM: the objective of the present investigation was to establish the antioxidant and radioprotective effects of amifostine on the organ of Corti of albino guinea pigs irradiated in the head and neck region. MATERIALS AND METHODS: An experimental study conducted on four groups of guinea pigs were used; One group received only amifostine, one group was submitted to a single dose of 350 cGy and the other two were similarly irradiated but received amifostine doses of 100 or 200 mg/kg. All animals were slaughtered 30 days after the experiment, their bullae were removed and the damaged outer hair cells were counted. RESULT: The extent of injury was lower in the outer hair cells of the two groups treated with amifostine compared to the group that was only irradiated. There was no difference between the group treated with 100 and 200 mg/kg of amifostine. The group that received only amifostine had no cochlear damage. CONCLUSION: Amifostine is an effective cytoprotective substance in the Organ of Corti of irradiated guinea pigs.

A radiação pode causar lesão na orelha interna podendo provocar surdez sensório-neural e inclusive levar à anacusia. A amifostina é uma substância citoprotetora seletiva de tecidos sadios, amplamente utilizada durante a radio e quimioterapia de tumores malignos. OBJETIVO: O objetivo deste estudo experimental foi verificar se existe efeito antioxidante e radioprotetor da amifostina no órgão de Corti de cobaias albinas irradiadas em região de cabeça e pescoço. MATERIAL E MÉTODO: O estudo realizado envolveu quatro grupos de animais: um grupo foi submetido à irradiação em dose única de 350cGy. Dois grupos receberam a mesma dose de radiação, porém receberam doses de 100 e 200mg/kg de amifostina, 30 minutos antes da irradiação. Um grupo recebeu apenas amifostina, na dose de 200mg/Kg. Todas as cobaias foram sacrificadas 30 dias após o experimento e suas bulas retiradas para estudo em microscópio de varredura. RESULTADO: O grau de lesão das células ciliadas externas foi menor nos dois grupos que receberam a amifostina que no grupo apenas irradiado. Não foi encontrada diferença de proteção entre os grupos que receberam doses de 100 e 200mg/kg de amifostina. Não houve lesão no grupo que recebeu apenas amifostina. CONCLUSÃO: Amifostina mostrou ser um radioprotetor do órgão de Corti de cobaias albinas irradiadas.

Asunto(s)

RESUMEN

BACKGROUND: Amikacin is a semisynthetic aminoglycoside. It acts against most of the microbial species. Amikacin limitation of the therapeutic application is the ototoxicity which promotes permanent lesions in the cochlear system. Aminoglycoside antibiotics have ototoxic potential. The target cells are preferentially the outer hair cells in the cochlear basal turns. Amynoglicoside antibiotics can quelate iron forming a complex with oxidate properties and promotes the formation of free radicals. Responsible for production of lesions in the hair cells. OBJECTIVE: The objective of the present investigation was to determine whether the use of the aminoglycoside amikacin at small doses may lead to the occurrence of some types of resistance to or protection against ototoxicity of the drug by analyzing lesions to the organ of Corti by scanning electron microscopy. METHODS: The study was conducted on 31 guinea pigs that were divided into 4 groups, amikacin was administered intramuscularly. The groups consisted of: group A = control group: 5 animals (10 cochleae); group B = 5 animals (10 cochleae), amikacin 20 mg/kg/day for 30 days; group C = 7 animals (13 cochleae), amikacin 400 mg/kg/day for 12 days; group d = 14 animals (26 cochleae) amikacin 20 mg/kg/day for 30 days, followed by 400 mg/kg/day for 12 days. Histological studies were performed by scanning electron microscopy. Three cochleae were excluded. RESULTS: In groups A and B, the cells were normal in all cochleae, in group C there were extensive lesions of the 2 more basal turns, and in group D there was a significant reduction of lesions in the 2 more basal turns compared with group C, which had received the ototoxic dose of amikacin alone. CONCLUSION: We conclude that the non-ototoxic dose of amikacin administered before the ototoxic dose of the same antibiotic had a statistically significant protective effect on the 2 more basal turns of the guinea pig cochlea.

Asunto(s)

RESUMEN

Os medicamentos ototóxicos, sendo os antibióticos aminoglicosídeos mais comuns, podem provocar lesöes irreversíveis nas células ciliadas do órgäo de Corti e das máculas e cristas do sistema vestibular. A lesäo celular está relacionada com a formaçäo de substâncias complexas entre a droga ototóxica e os polifosfoinositídeos da membrana celular. O controle das funçöes auditiva e vestibular deve ser permanente durante a utilizaçäo desses medicamentos, sobretudo se existem fatores de risco. Experimentalmente, as lesöes induzidas têm sido estudadas em animais por métodos eletrofisiológicos, com registro dos potenciais colcleares e dos potenciais do tronco cerebral, e por métodos histológicos, com técnicas de preparaçäo de superfície do órgäo de Corti, microscopia eletrônica e isolamento de células ciliadas em meio de cultura

Asunto(s)