The Mild Cognitive Impairment Screen (MCIS) is a computer-based cognitive assessment designed for clinical and research use in detecting amnestic mild cognitive impairment (aMCI). Performance on the MCIS is reported as the Memory Performance Index (MPI). However, the comparability between the MPI and traditional neuropsychological tests in detecting aMCI, and in differentiating it from Alzheimer’s disease (AD) and normal aging has not been examined. A cross-sectional study was conducted to assess the validity of the MPI relative to standard neuropsychological measures. Participants included 12 individuals diagnosed with aMCI, 49 with mild AD, and 25 healthy elderly. The MCIS significantly discriminated among aMCI, AD, and healthy elderly controls. The MCIS is effective in detecting aMCI, and in discriminating it from cognitive changes observed in AD and normal aging. The MCIS may be a valuable tool in the identification of elderly at high risk for dementia due to its ease-of-use and brief administration time.
mu-Calpain quickly split the alpha-connectin in myofibrils into beta-connectin, and then produced a 1700-kDa component. Cathepsin D also split alpha-connectin into beta-connectin, further degrading it to fragments smaller than the 1700-kDa component with increasing incubation time. The action of cathepsin D on the connectin molecule was distinctly different from that of mu-calpain in terms of the splitting rate and manner. When freshly excised muscle was exposed to a temperature of 37 degrees C, complete disappearance of connectin (alpha, beta and 1700-kDa component) was observed within 36 h. In contrast, at 2 degrees C, about 75% of connectin was retained as beta-form even after 3 weeks. The present data suggest that the degradation of connectin in muscle might be caused by mu-calpain in the early stage of aging, and then with time, this action is replaced by m-calpain or cathepsin D. However, the possibility of other intrinsic proteases participating in the degradation of connectin still remains.
The factors affecting the conversion of alpha-connectin to beta-connectin induced by pressurization of muscle were investigated over a pressure range from 100 to 400 MPa by using SDS-PAGE and immunoblot analysis. When muscles were exposed to high pressures, the conversion of alpha-connectin to beta-connectin was the most pronounced at a pressure of 300 MPa, and the appearance of 1,200-kDa peptide accompanied by conversion of alpha- to beta-connectin was observed. Connectin was relatively resistant to degradation under a pressure of 400 MPa. The degradative products of beta-connectin reactive with mAb 2D4 were not observed. The effect of high pressure on connectin in isolated myofibrils was similar to that on connectin in muscle. Addition of leupeptin and E-64 to the isolated myofibrils resulted in the prevention of the degradation of connectin at each stage of the pressurization. The ability of calcium-activated protease (calpain) to hydrolyze connectin from alpha to beta gradually declined with increasing pressure. The results indicate that calpain is responsible for the pressure-induced conversion of alpha- to beta-connectin. The rate of this conversion is probably regulated by the pressure-dependent structural change of alpha-connectin and inactivation of calpain.
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