Sensory-feedback system compatible with myoelectric control

Progress in the development of a system to provide sensory feedback of the pinch force of an artificial hand is described. Design criteria relating to electrocutaneous stimulation and compatibility with myoelectric control are discussed. Details of a practical system, presently in use by two amputees prior to full-scale clinical evaluation, are presented.     

Validity of predicting mean arterial blood pressure during exercise

PURPOSE: Mean arterial blood pressure (mean arterial pressure (MAP)) at rest is conventionally estimated as the product of the diastolic pressure plus one-third of the pulse pressure. Since pulse wave forms and the duration of diastole change during exercise, one might question the validity of this prediction equation for the exercise state. Our purpose was to test this by directly measuring blood pressure over a wide range of exercise intensities. METHODS: Pressure was recorded by arterial catheterization in 29 subjects performing progressive exercise and/or constant-load exercise at different intensities. Actual MAP was measured by integrating the area under the pulse curve and compared it with the value which was predicted from systolic and diastolic measures over heart rates ranging from 100 to 200 beats x min(-1). RESULTS: Predicted values were quite close to actual MAP, and the accuracy of the prediction equation changed minimally with increased exercise intensity. CONCLUSION: This method provides a valid estimation of MAP during exercise.     

Multiecho water‐fat separation and simultaneous R estimation with multifrequency fat spectrum modeling

Multiecho chemical shift–based water‐fat separation methods are seeing increasing clinical use due to their ability to estimate and correct for field inhomogeneities. Previous chemical shift‐based water‐fat separation methods used a relatively simple signal model that assumes both water and fat have a single resonant frequency. However, it is well known that fat has several spectral peaks. This inaccuracy in the signal model results in two undesired effects. First, water and fat are incompletely separated. Second, methods designed to estimate T in the presence of fat incorrectly estimate the T decay in tissues containing fat. In this work, a more accurate multifrequency model of fat is included in the iterative decomposition of water and fat with echo asymmetry and least‐squares estimation (IDEAL) water‐fat separation and simultaneous T estimation techniques. The fat spectrum can be assumed to be constant in all subjects and measured a priori using MR spectroscopy. Alternatively, the fat spectrum can be estimated directly from the data using novel spectrum self‐calibration algorithms. The improvement in water‐fat separation and T estimation is demonstrated in a variety of in vivo applications, including knee, ankle, spine, breast, and abdominal scans. Magn Reson Med 60:1122–1134, 2008. © 2008 Wiley‐Liss, Inc.     

HIV-Related Stigma and Psychological Adjustment Among Perinatally HIV-Infected Youth in Cape Town,South Africa

AIDS and Behavior - The effect of chronic HIV-infection on psychological adjustment, including the impact of HIV-related stigma in perinatally HIV-infected (PHIV+) youth across Africa is largely...     

Characterization of metalloprotease cleavage products of human articular cartilage

OBJECTIVE: To identify, characterize, and compare proteolysis peptide products generated by metalloprotease digests of human articular cartilage. METHODS: Human articular cartilage was digested by the addition of exogenous metalloproteases, including matrix metalloproteinases 2, 3, 8, 9, 12, and 13 and aggrecanases ADAMTS-4 and ADAMTS-5. Proteolyzed peptide products were identified by proteomics methods using mass spectrometry. RESULTS: Complete sequences of the peptides proteolyzed from human articular cartilage, including N- and C-termini and hydroxylated posttranslational modifications, were determined. A wide variety of peptides, originating from types I, II, and III collagen, biglycan, prolargin, fibromodulin, fibronectin, decorin, cartilage oligomeric matrix protein, cartilage intermediate-layer protein, megakaryocyte-stimulating factor, mimecan, aggrecan, and lumican, was analyzed following metalloprotease digestion. Release of peptides varied as a function of time, enzyme specificity, and abundance. Specific type II collagen peptide biomarkers, including those containing the three-quarter-length fragment cleavage site and those containing the domains for helical peptide of type II collagen and C-telopeptide of type II collagen, were observed after release by selected proteases. CONCLUSION: The use of intact cartilage instead of purified protein substrates in the assay allowed for the identification of novel potential substrates and cleavage sites for individual enzymes under more physiologically relevant conditions. Characterization of these cartilage matrix peptides may help in the development of pharmacodynamic biomarkers of cartilage degradation, and also may contribute to an understanding of the bioactive peptides important in chondrocyte signaling.