Medical engineering & physics
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Osteoporotic/osteopenia fractures occur most frequently in trabeculae-rich skeletal sites. The purpose of this study was to use a high-resolution micro-computed tomography (micro-CT) and dual energy X-ray absorptionmeter (DEXA) to investigate the changes in micro-architecture and bone mineral density (BMD) in a sheep model resulted from ovariectomy (OVX). Biomechanical tests were performed to evaluate the strength of the trabecular bone. ⋯ In OVX sheep, changes in the structural parameters of trabecular bone are comparable to the human situation during osteoporosis was induced. The sheep model presented seems to meet the criteria for an osteopenia model for fracture treatment with respect to morphometric and mechanical properties. But the duration of OVX must be longer than 12 months to ensure the animal model can be established successfully.
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Diffusion-weighted magnetic resonance imaging has the ability to map neuronal architecture by estimating the 3D diffusion displacement within fibrous brain structures. This approach has non-invasively been demonstrated in the human brain with diffusion tensor tractography. Despite its valuable application in neuroscience and clinical studies however, it faces an inherent limit in mapping fiber tracts through areas with intervoxel incoherence. ⋯ The Q-ball imaging method was adopted to acquire the diffusion displacements. Human motor pathways with seed points from the internal capsule, motor cortex, and pons were studied respectively. The results were consistent with known anatomy and demonstrated the promising potential of the MFACT method in mapping the complex neuronal architecture in the human brain.
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Steady-state visual evoked potentials (SSVEP) are increasingly used in the development of brain-computer interface techniques (BCI). We investigated the spectrum differences of three kinds of flickers and the differences in SSVEPs evoked by three different stimulators, i.e. the light-emitting diode, the cathode ray tube of a desktop monitor and the liquid crystal display of a laptop screen. The results showed that the SSVEP differences were strongly related to the frequency spectrum differences of the flickers. According to these differences, the stimulator was selected based on the complexity of the BCI system.
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Recording surface electromyogram (EMG) signals from sphincter muscles has become of increasing interest due to potential applications in diagnosis or investigation of the mechanisms of incontinence. Recently developed probes allow high-resolution detection of EMG signal from the external anal sphincter. One of the main issues in the interpretation of experimental signals is the detection volume of the recording electrodes. ⋯ The detection volume of EMG recording systems from sphincter muscles extends more in the axial than in the depth direction and is affected by many parameters that cannot be estimated in practical situations, thus introducing a rather large variability in the muscle portion investigated among subjects. More selective information can be obtained using the recently developed multi-channel probe with respect to classical probes. Selectivity is increased with small electrodes and double differential recordings.
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Bisphosphonates are commonly used for the treatment of osteoporosis and have recently been shown to increase bone mineral parameters and strength in endochondral fracture repair. There is concern, however, that BPs may negatively affect bone material properties. ⋯ The results from this preliminary data suggest that single dose zoledronic acid treatment in fracture healing may not adversely affect the intrinsic properties of callus bone tissue. Single dose bisphosphonate may be a viable treatment for augmenting fracture repair without negatively affecting the material properties.