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 presentation. OBJECTIVE: To confirm if conditioning with an agent different from the used to cause the trauma can also be effective. METHOD: Experimental study with 17 guinea pigs divided as follows: group Som: exposed to 85 dB broadband noise centered at 4 kHz, 30 minutes a day for 10 consecutive days; group Cont: intramuscular administration of gentamicin 160 mg/kg a day for 10 consecutive days; group Expt: conditioned with noise similarly to group Som and, after each noise presentation, received gentamicin similarly to group Cont. 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 to the ones that received only the ototoxic gentamicin administration. This lack of protection was observed functionally and morphologically. CONCLUSION: Conditioning with 85 dB broadband noise, 30 min a day for 10 consecutive days does not protect against an ototoxic gentamicin administration of 160 mg/kg a day for 10 consecutive days in the guinea pig

Seletividade do herbicida Trifloxysulfuron sodium para fins de fitorremediação

Este trabalho teve como objetivo selecionar plantas tolerantes ao trifloxysulfuron sodium, visando utilizá-las em programas de fitorremediação. Foram avaliadas dez espécies: Calopogonium muconoides, Crotalaria spectabilis, Vicia sativa, Cajanus cajan, Nicotiniana tabacum, Ricinus communis, Penisetum glauctun, Mucura cinereum, Mucura aterrima e Capinas albus. O delineamento experimental utilizado foi o de blocos ao acaso, em parcelas subdivididas, com três repetições. Nas parcelas aplicaram-se as doses de trifloxysulfuron sodium (U,00; 3,75; 7,50; e 15,00 g ha') e, nas subparcelas, as épocas de avaliação (15, 34, 45 e 60 dias após a semeadura -DAS). Foram avaliados a altura de plantas, os sintomas de toxicidade e, aos 60 DAS, também a biomassa seca da parte aérea, das raízes e total das plantas. Todas as espécies sobreviveram ao trifloxysulfuron sodium no solo, mesmo quando aplicado em dose duas vezes maior que a recomendada pelo fabricante (15,00 g ha'), com exceção de N. tabacum, que não sobreviveu a essa d se. M. aterrima, L. albus, C muconoides, C. spectabilis e M. cinereum foram as espécies que apresentaram maior tolerância ao trifloxysulfuron sodium.The aim of this study was the selectioa of trifloxysalfuron sodiam~selective plants to use them in phytoremediation programs against this herbicide in the soil. Ten species were evaluated: Calopogorzium muconoides, Crotalaria Spectabih’s, Vicia sativa, Cajanus cajan. Nicotiniana tabaeum, Ricinus communis, Penisetum glaucum, Muczmd cinereum, Mucuna atem'ma and Lupinus albus. A randomizedwcomplete block design with split-plots and three replications was used. The factor applied to the plots were the doses of trifloxysulfuron sodium (0.00, 3.75, 7.50, and 15.00 3 ha'*) and, in the split-plots, the evaluation times [15, 30, 45, and 60 days after sowing (DASH. Plant height, and phytotoxicity were evaluated and, at 60 DAS, above~ground, root and total biomass dry matter. It was verified that all the species survived to trifloxysulfuron sodium presence in the soil, even when applied in double the dose recommended by the manufacturer (15.00 g ha‘l), except for N. tabacum, that did not survive this dose. M. aterrima. L. albus, C. muconoz'des, C. spectabilis and M. cinereum were most tolerant to tribloxysulfuron sodium