Ear and electrode effects reduce within-group variability in middle latency response amplitude measures

Objectives: To establish normative amplitude values for relative difference measurements of the middle latency response (MLR) in normal-hearing pediatrics and to determine if these measurements provided a significant reduction of within-group variability when compared to raw, absolute amplitude measures. A relative amplitude difference is defined in the present paper as the difference in Na-Pa amplitude between two electrodes (e.g. vertical bar Na-Pa at C3 minus Na-Pa at C4 vertical bar, or electrode effects) or between two ears (e.g. vertical bar Na-Pa on left ear stimulation minus Na-Pa on right ear stimulation vertical bar, or ear effects). In contrast, an absolute amplitude is defined as a single Na-Pa measurement made at one electrode for stimulation of one ear (e.g. Na-Pa measured at C3 on left ear stimulation). Design: Cross-sectional study. Study sample: 155 pediatrics with normal peripheral and central hearing, and no history of psychological, neurological, or learning disability issues. Results: Within-group variability was significantly smaller for relative differences when compared to absolute amplitude measures. Electrode effects showed significantly less variability than ear effects. Normative values for ear and electrode effects were reported. Conclusions: Relative differences may provide better utility in the clinical diagnosis of central auditory pathology in pediatrics when compared to absolute amplitude measures because these difference measures show significantly lower variability when examined across subjects.

Proteome analysis of spinal cord during the clinical course of monophasic experimental autoimmune encephalomyelitis

The induction of autoimmune encephalomyelitis (EAE) in Lewis rats results in a period of exacerbation followed by complete recovery. Therefore, this model is widely used for studying the evolution of multiple sclerosis. In the present investigation, differentially expressed proteins in the spinal cord of Lewis rats during the evolution of EAE were assessed using the combination of 2DE and MALDI-TOF MS. The majority of the differentially expressed proteins were identified during the acute phase of EAE, in relation to naive control animals. On the other hand, recovered rats presented a similar protein expression pattern in comparison with the naive ones. This observation can be explained, at least in part, by the intense catabolism existent in acute phase due to nervous tissue damage. In recovered rats, we have described the upregulation of proteins that are apparently involved in the recovery of damaged tissue, such as light and medium neurofilaments, glial fibrillary acidic protein, tubulins subunits, and quaking protein. These proteins are involved mainly in cell growth, myelination, and remyelination as well as in astrocyte and oligodendrocyte maturation. The present study has demonstrated that the inflammatory response, characterized by an increase of the proliferative response and infiltration of autoreactive T lymphocytes in the central nervous system, occurs simultaneously with neurodegeneration.