Search

In this study, we developed a balance assessment system in which the visual stimulus was generated by a virtual reality (VR) technique and somatosensation was obtained from a movable platform. By standing on the movable platform, the center of pressure (COP) was measured to express the subject''s postural control in response to varied visual stimuli. From the COP data, a singular value decomposition technique was used to derive the sway area and direction, represented in a polar form. Our system demonstrated the feasibility of using a VR environment in postural control trials and provided more realistic somatosensory and visual inputs. [Copyright &y& Elsevier]

Abstract: Caffeic acid phenethyl ester (CAPE) is an active component of propolis that exhibits cardioprotective and antiarrhythmic effects. The detailed mechanisms underlying these effects, however, are not entirely understood. The aim of this study was to elucidate the electromechanical effects of CAPE in guinea-pig cardiac preparations. Intracardiac electrograms, left ventricular (LV) pressure, and the anti-arrhythmic efficacy were determined using isolated hearts. Action potentials of papillary muscles were assessed with microelectrodes, Ca2+ transients were measured by fluorescence, and ion fluxes were measured by patch-clamp techniques. In a perfused heart model, CAPE prolonged the atrio-ventricular conduction interval, the Wenckebach cycle length, and the refractory periods of the AV node and His–Purkinje system, while shortening the QT interval. CAPE reduced the occurrence of reperfusion-induced ventricular fibrillation and decreased LV pressure in isolated hearts. In papillary muscles, CAPE shortened the action potential duration and reduced both the maximum upstroke velocity and contractile force. In fura-2-loaded single ventricular myocytes, CAPE decreased cell shortening and the Ca2+ transient amplitude. Patch-clamp experiments revealed that CAPE produced a use-dependent decrease in L-type Ca2+ current (I Ca,L) (IC 50=1.1μM) and Na+ current (I Na) (IC 50=0.43μM), caused a negative-shift of the voltage-dependent inactivation and a delay of recovery from inactivation. CAPE decreased the delayed outward K+ current (I K) slightly, without affecting the inward rectifier K+ current (I K1). These results suggest that the preferential inhibition of Ca2+ inward and Na+ inward currents by CAPE may induce major electromechanical alterations in guinea-pig cardiac preparations, which may underlie its antiarrhythmic action. [Copyright &y& Elsevier]

Abstract: Gait disturbances similar to those of human Parkinson''s disease (PD) can be observed in animals after administration of neurotoxin 6-hydroxydopamine (6-OHDA) to induce unilateral nigrostriatal dopamine depletion. However, the relationship between gait disturbances and dopamine depletion following 6-OHDA infusion has not been determined. The present study investigated the longitudinal changes of spatiotemporal gait patterns using a walkway system to acquire footprints and lateral limb images over a 6-week period following unilateral 6-OHDA injection into the medial forebrain bundle of rats. Our results indicated that hemiparkinsonian rats exhibited changes in gait patterns, as compared to normal controls, and pre-lesion levels, including a significantly decreased walking speed and step/stride length as well as an increased base of support and foot angle. The relative percentage of the gait cycle was also altered, showing an increase in the stance to swing ratio, which was more evident in the affected hindlimb. Time-course observations showed that these gait disturbances occurred as early as 4 days post-lesion and gradually increased up to 42 days post-injury. The extents of gait disturbances were compared with conventional apomorphine-induced turning behavior and akinesia bar tests, which were also apparent at 4 days post-lesion but remained relatively unchanged after 28 days. Our time-course gait analysis of a unilateral 6-OHDA rodent model provides insight into the compensatory changes of motor functions during the 6-week development of a nigrostriatal lesion, which might be useful for future objective assessment of novel treatments for human PD subjects. [Copyright &y& Elsevier]

Compared to the X-ray approach, footprint analysis is a non-radiation and more viable method for clinical assessment of the medial longitudinal arch of the foot. In this study, we have designed an optical footprint acquisition system that consists of a digital camera and two pieces of glass, each with four load cells under each corner. When the subject stands on the transparent force plates, the digital camera is triggered, photographing the soles of the feet at the moment when both feet bear approximately at the same weight. A blue gel is placed between the foot and the force plate to enhance the contrast between sole and background. Based on the relationship between the brightness of the image and the thickness of the gel, the three-dimensional (3D) structure of the arch can be reconstructed which can provide more representative information than a conventional footprint image, with its low resolution and easy smearing. [Copyright &y& Elsevier]