We have investigated how visual information of a scene, moving along the line of sight of a subject, affects postural readjustments made by a subject when instructed to maintain an upright posture. Two different types of stimulus patterns were presented each inducing a different optic flow field. In one case an optic flow field was induced by simulating motion of a subject relative to a wall and in the second case by stimulating motion of a subject through a tunnel. In both cases clear effects on postural balance were observed. It suggests that postural responses are invariant for the structure of the moving environment. The amplitude of the postural responses did not depend on the velocity of the simulated motion, and therefore did not depend on the absolute magnitude of the optic flow components. The amount of texture in the moving scene proved to be an important factor. In addition, it was found that the control of postural balance is not exclusively dominated by information provided by the peripheral part of the subject's visual field. Moreover, the results indicate that the divergence component in the optic-flow field alone is not sufficient to control posture in forward/backward direction.

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The purpose of this study was to examine the properties of the venous vascular system in the lower extremities of individuals with long-standing paraplegia (PP). The venous volume variations (VVV) , the venous capacity (VC), the venous emptying rate (VER) and the venous flow resistance (VFR) were measured in the left calf of 14 male PP and 12 male able-bodied subjects (ABS) by means of strain-gauge occlusion plethysmography. VVV and VC were significantly lower in PP compared to ABS, -45% and -50% respectively. Both groups showed a similar resting venous pressure in the calf (PP = 24.4 mmHg; ABS = 19.6 mmHg). VER was significantly lower (-60%) and hence VFR was significantly higher (+75%) in PP compared to ABS. This study demonstrates that the venous vascular properties in the legs of individuals with paraplegia have changed, i. e. a decrease in venous distensibility and capacity and an increase in venous flow resistance. This is most probably the result of vascular adaptations to inactivity and muscle atrophy rather than the effect of a non-working leg-muscle pump and sympathetic denervation.

Most patients with severe PTS had a combination of deep and superficial reflux. Reflux in the deep proximal veins contributes significantly to the PTS.

Duplex ultrasonography is important in the diagnosis of vasculogenic erectile dysfunction. We measured the ultrasonographic parameters of cavernous blood flow in different phases of penile erection. We examined 44 volunteers with normal erectile potency. Doppler spectra of the cavernous artery were obtained in a time-dependent manner after intracavernous administration of papaverine. Following intracavernous pharmacological stimulation, the Doppler spectrum alters according to a specific pattern indicating the different hemodynamic phases of erection. Peak flow velocity and acceleration time, measured in the early post-injection phase, may be used to grade arterial inflow. The difference between resistance index in the pre-injection and late post-injection phases may be used to estimate veno-occlusive function. References values are defined.