ABSTRACT
Subjects suffering from spinal cord injury with lower extremity impairment generally use a wheelchair to move. However, some of them are capable of walking with the help of orthoses and crutches. Standing up and walking regularly have huge benefits for the general health state of these subjects, since it reduces the negative consequences of sedentarism. Therefore, achieving adherence to assisted gait is important, but there is a risk of abandoning due to several issues such as pain, fatigue, or very low speed, which can make the subject return to solely use the wheelchair. Musculoskeletal models can provide estimations of muscular forces and activations, which in turn enable to calculate magnitudes such as joint reactions, energetic cost, and bone stress and strain. These magnitudes can serve to evaluate the impact of assisted gait in the subject's health and to assess the likelihood of adherence. Moreover, they can be used as indicators to compare different assistive devices for a particular subject. As every spinal cord-injured (SCI) subject represents a different case, a procedure to define customized musculoskeletal models for the crutch-orthosis-assisted gait of SCI subjects is proposed in this paper. Issues such as selection of muscles and integration of models of trunk, upper and lower extremities, and assistive devices (crutches and orthoses) are addressed. An inverse-dynamics-based physiological static optimization method that takes into account muscle dynamics at low computational cost is applied to obtain estimates of muscle forces and joint reactions. The method is experimentally validated by electromyography in a case study.
Subject(s)
Crutches , Gait , Humans , Orthotic DevicesABSTRACT
Dictyophora echinovolvata is a kind of edible mushroom in the Dictyophora genus, of which polysaccharide is an important chemical substance. Herein, three polysaccharide fractions (DEP-4P, DEP-6P and DEP-8P) were prepared from water extract of D. echinovolvata using gradient ethanol precipitation method. Their chemical structures were analyzed by methylation analysis and 1D/2D NMR spectroscopy. Molecular weights were determined by multi-angle laser light scattering combined with size-exclusion chromatography (HPSEC-MALLS). HPSEC data showed that DEP-4P had the highest values of molecular weight, intrinsic viscosity and hydrodynamic radius. DEP-6P and DEP-8P had lower molecular weights, which contributed to their easily distinguished 1D and 2D NMR spectra. Methylation and NMR analysis suggested that the three fractions were linear α-(1â¯ââ¯4)-glucans with α-Glcp residues linked to the backbone at C-6. Differences among the three fractions were the molar ratios of the identified glycosidic bonds. Repeating units of polysaccharides from D. echinovolvata were proposed as follows.
