Miguel Ângelo Hyppolito

Ototoxicidade por organofosforados: descrição dos aspectos ultraestruturais do sistema vestibulococlear de cobaias

UNLABELLED Organophosphate toxic agents are used in agriculture and are currently part of the group of toxic agents which can lead to hearing loss, in which we have solvents, metals and asphyxiation agents. AIM To analyze the acute ototoxic action of a group of organophosphate agents in the vestibulo-cochlear system. This is a prospective experimental study. MATERIALS AND METHODS We used male albino guinea pigs, broken down into three groups, to which we provided distilled water (group 1 - control), agrotoxic agent - 0.3 mg/Kg/day (group 2), agrotoxic - 3 mg/Kg/day (group 3), during 7 seven consecutive days. The most used agrotoxic agent was Tamaron BR (metamidophos). The anatomical evaluation of the cochlea, saccule and utricle was carried out by means of electronic scanning microscopy after the use of the agrotoxic agent. RESULTS The guinea pigs submitted to the organophosphate presented cochlear morphological alterations with lesions on the three turns analyzed, as well as cilia alterations in the saccule and utricle, intensified according to the agent dosage. CONCLUSION The morphological alterations seen in the hair cells exposed to daily doses of organophosphate promote evidences of an acute deleterious effect of agrotoxic agents on the vestibulo-cochlear system.

Biosilicate® Ototoxicity and Vestibulotoxicity evaluation in guinea-pigs

UNLABELLED Changes, destructions and interruptions in middle ear ossicular chain architecture may be caused by infection, trauma, tumors, congenital alterations or prior surgeries. Nonetheless, infectious and inflammatory processes, focal or generalized which affect the middle ear are the most prevalent, causing a great demand for ossiculoplasty. Biosilicato is a new material which can be used in the middle ear with the goal of reconstructing the ossicular chain. It is a bioactive type A vitroceramic, in other words, it binds to bone or soft tissue in a matter of a few hours, thanks to the formation of hydroxy-carbonateapatatie in its contact surface when in contact with body fluids. AIMS The goal of the present paper is to assess biosilicate ototoxicity and vestibular toxicity in experimental animals, for later use in humans. MATERIALS AND METHODS This a clinical and experimental study in which otoacoustic emissions were performed before and after the placement of Biosilicate in the middle ear of experimental animals and a scanning electron microscopy was carried out in the cochlea, saccule, utriculus and macula of the semicircular canals after 30 and 90 days to assess oto and vestibular toxicity. RESULTS There were no signs of oto or vestibular toxicity in any of the groups associated with biosilicate. CONCLUSION Biosilicate is a safe material to be used in ossiculoplasties.

The role of hyperbaric oxygen therapy (HOT) as an otoprotection agent against cisplatin ototoxicity

PURPOSE Hyperbaric oxygen therapy (HOT) consists of intermittent inhalations of 100% oxygen at a pressure higher than 1 atm. It is an important adjuvant therapy in pathological processes like soft tissue infections, radiation injury, gas gangrene, osteomyelitis and decompressive diseases. Cisplatin, a potent antineoplastic drug, widely used in cancer therapy is highly ototoxic causing bilateral, irreversible damage to the hearing of high frequency sounds (4-8 KHz). OBJECTIVE This experimental study conducted at the Faculty of Medicine of Ribeirao Preto, University of Sao Paulo aims to evaluate Hyperbaric Oxygen Therapy as an otoprotection agent against drug toxicity. METHODS Albino guinea pigs were divided into two groups: in Group A, 5 animals (10 cochlea) received cisplatin, i. p., 8.0 mg/kg/day during three days and afterwards were submitted to HOT; in Group B, 3 animals (6 cochlea) received cisplatin, i. p. 8.0 mg/kg/day during three days. Guinea pigs were evaluated by acoustic otoemissions (AOE) and scanning electron microscopy (SEM). RESULTS Group B animals showed loss of auditory functions as measured by AOE and distorted outer hair cells by SEM. In Group A, outer hair cells shown by SEM images were mostly preserved. CONCLUSION It is presumed that Hyperbaric Oxygen Therapy has a protector effect against cisplatin ototoxicity.

Analysis of postural control and muscular performance in young and elderly women in different age groups

BACKGROUND: muscle strength and power are two factors affecting balance. The impact of muscle strength and power on postural control has not been fully explored among different age strata over sixty. OBJECTIVES: the aim of the present study was to assess the muscle strength and power of elderly women in different age groups and determine their correlation with postural control. METHOD: eighty women were divided into four groups: the young 18-30 age group (n=20); the 60-64 age group (n=20); the 65-69 age group (n=20); and the 70-74 age group (n=20). The participants underwent maximum strength (one repetition maximum or 1-RM) and muscle power tests to assess the knee extensor and flexor muscles at 40%, 70%, and 90% 1-RM intensity. The time required by participants to recover their balance after disturbing their base of support was also assessed. RESULTS: the elderly women in the 60-64, 65-69, and 70-74 age groups exhibited similar muscle strength, power, and postural control (p>0.05); however, these values were lower than those of the young group (p<0.05) as expected. There was a correlation between muscle strength and power and the postural control performance (p<0.05). CONCLUSION: despite the age difference, elderly women aged 60 to 74 years exhibited similar abilities to generate strength and power with their lower limbs, and this ability could be one factor that explains the similar postural control shown by these women.

Efeito da oxigenação hiperbárica em lesão ototóxica produzida pela amicacina em cobaias

UNLABELLED Hyperbaric oxygen therapy (HBOT) has enhanced the prevention and treatment of auditory ailments such as ototoxicity. OBJECTIVE To study the effects of HBOT upon ototoxic injuries produced by amikacin. METHOD This experimental study included 12 albino guinea pigs, whose auditory function was assessed through distortion product otoacoustic emissions (DPOAEs) and brainstem auditory evoked potentials (BAEPs) before and after the administration of amikacin (600 mg/kg/day) and HBOT sessions (2 ATA, 60 minutes). Morphological features were analyzed through scanning electron microscopy. Subjects were divided into four groups, as follows: group 1 - saline solution + HBOT; group 2 - amikacin for 8 days; group 3 - amikacin + seven days of rest; and group 4 - amikacin + HBOT. RESULTS Group 1 subjects had preserved function and morphology throughout the experiment; Group 2 subjects had statistically significant levels of hair cell injury and functional impairment; Subjects on groups 3 and 4 had statistically significant functional and morphological impairment after the administration of amikacin, which were still present after the proposed procedures had been carried out. CONCLUSION Hyperbaric oxygen therapy did not change the cochlear hair cell morphology or the electro-physiological thresholds of the guinea pigs given amikacin.

Alterações no sistema vestibulococlear decorrentes da exposição ao agrotóxico: revisão de literatura

Os agrotoxicos sao amplamente utilizados no meio rural e sua larga utilizacao, desprovida de medidas de biosseguranca apropriadas, vem provocando impactos potenciais tanto para a degradacao ambiental quanto para o organismo humano, aumentando a incidencia de intoxicacoes ocupacionais. O objetivo do presente estudo foi revisar e discutir a respeito da exposicao aos agrotoxicos e sua influencia na funcao e estrutura do sistema auditivo. Foram revisados periodicos nacionais e internacionais relevantes indexados no PubMed, Medline, Bireme e LILACS, assim como capitulos de livros e dissertacoes publicados no periodo entre 1987 e 2009. As pesquisas sugerem que a exposicao, principalmente cronica, aos agrotoxicos induz a alteracoes funcionais no sistema vestibulococlear, manifestando ainda uma serie de sinais e sintomas. Apesar da escassez de dados sobre a influencia do organofosforado nas caracteristicas morfologicas do aparelho auditivo, os estudos indicam que a exposicao de carater agudo aos agrotoxicos pode tambem ser responsavel por alteracoes no sistema auditivo, caracterizadas por lesoes estruturais na coclea, principalmente nas celulas ciliadas externas.

Implicações do uso do Aparelho de Amplificação Sonora Individual na qualidade de vida de idosos

PURPOSE To evaluate through standardized questionnaires the quality of life of elderly people with hearing loss diagnosed with and without the use of hearing aids (HA) and elderly without hearing complaints. METHODS This is a cross-sectional study with non probabilistic sample, divided into three groups divided as follows: 30 elderly people with diagnosed hearing loss and indication for use of individual sound amplification devices (hearing aids), but have not yet made use of the prosthesis; 30 individuals with hearing impairment who used hearing aids and 30 elderly without hearing complaints. Participants completed a questionnaire investigating sociodemographic and family data, the Hearing Handicap Inventory for the Elderly Screening Version (HHIE-S) and the World Health Organization Quality of Life - Short version (WHOQOL-BREF). In addition to the descriptive analysis of the data were performed tests to compare the three groups by applying analysis of variance (ANOVA) and the Bonferroni post hoc test. RESULTS The three groups differed significantly in all domains of quality of life. The group of the elderly people with hearing loss diagnosed and with indication for the use of hearing aids presented lower scores and the group of the elderly with hearing disabilities that used the hearing aid and that the reference group. The AASI group presented the best quality of life results. CONCLUSION The hearing loss affects the quality of life of the elderly. The effective use of hearing aid is beneficial to this population, improving their living and health conditions.

Lack of protection against gentamicin ototoxicity by auditory conditioning with noise

INTRODUCTION Auditory conditioning consists of the pre-exposure to low levels of a potential harmful agent to protect against a subsequent harmful exposure. OBJECTIVE To confirm if conditioning with an agent different from that used to cause the trauma can also be effective. METHODS This was an experimental study with 17 guinea pigs, divided into three groups: an ototoxic control group (Cont) that received intramuscular administration of gentamicin 160 mg/kg/day for ten consecutive days, but no sound exposure; a sound control group (Sound) that was exposed to 85 dB broadband noise centered at 4 kHz, 30 min each day for ten consecutive days, but received no ototoxic medications; and an experimental group (Expt) that received sound exposure identical to the Sound group and after each noise presentation, received gentamicin similarly to Cont group. The animals were evaluated by distortion product otoacoustic emissions (DPOAEs), brainstem auditory evoked potentials (BAEPs), and scanning electron microscopy. RESULTS The animals that were conditioned with noise did not show any protective effect compared with the ones that received only the ototoxic gentamicin administration. This lack of protection was observed functionally and morphologically. CONCLUSION Conditioning with 85 dB broadband noises, 30 min a day for ten consecutive days does not protect against an ototoxic gentamicin administration of 160 mg/kg/day for ten consecutive days in the guinea pig.