Mismatch Negativity (MMN) response studies in elderly subjects

Mismatch Negativity é potencial endógeno que reflete o processamento de diferenças ocorridas no estímulo acústico. OBJETIVO: Caracterizar as respostas do MMN em sujeitos idosos, comparar com sujeitos adultos. MATERIAL E MÉTODO: Estudo prospectivo, com 30 sujeitos, 15 do gênero masculino e 15 do gênero masculino, com idade entre 60 e 80 anos e 11 meses. Teste estatístico Mann-Whitney. Os sujeitos passaram por avaliação médica e pelos exames de Audiometria Tonal Liminar, Imitanciometria, Emissões Otoacústicas e Potenciais Auditivos de Curta e Longa Latência (MMN). RESULTADOS: A latência média foi de 161,33ms (CZA2) e 148,67ms (CZA1), gênero feminino; de 171ms (CZA2) e 159,07ms (CZA1), gênero masculino. A amplitude média foi de -2,753µV (CZA2) e -2,177µV (CZA1), gênero feminino; de -1,847µV (CZA2) e -1,953µV (CZA1), gênero masculino. Quanto aos hemisférios direito e esquerdo, variável latência, média de 166ms (CZA2) e 153,87ms (CZA1); para a variável amplitude, média de -2,316µV (CZA2) e -2,065µV (CZA1). CONCLUSÃO: Não há diferença estatística significante entre as variáveis latência e amplitude, ao se comparar os gêneros masculino e feminino, os lados direito e esquerdo nos sujeitos idosos e entre as idades cronológicas adultos e idosos.Mismatch Negativity is an endogenous potential which reflects the processing of differences incurred in the acoustic stimulus. AIM: to characterize MMN responses in elderly subjects and compare with adult subjects. MATERIALS AND METHODS: prospective study involving 30 subjects, 15 men and 15 women, aged between 60 and 80 years and 11 months. Statistical test: Mann-Whitney. The subjects went through medical evaluation, threshold tonal audiometry, immittance tests, otoacoustic emissions and short and long latency auditory potentials (MMN). RESULTS: mean latency was 161.33 ms (CZA2) and 148.67 ms (CZA1), in women; of 171 ms (CZA2) and 159.07 ms (CZA1), men. Mean amplitude was -2.753 µV (CZA2) and -2.177 µV (CZA1), women; -1.847 µV (CZA2) and -1.953 µV (CZA1), men. As to the right and left hemispheres, mean latency variable of 166 ms (CZA2) and 153.87 ms (CZA1); for the amplitude variable, mean value of -2.316 µV (CZA2) and -2.065 µV (CZA1). CONCLUSION: there is no statistically significant difference between the latency and amplitude when we compared males and females, right and left sides in the elderly and between chronologic ages between adults and elderly subjects

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved