Previous experiments have demonstrated that the vestibular system contributes to regulating sympathetic nervous system activity, particularly the discharges of vasoconstrictor fibres. In the present study, we examined the physiological significance of vestibulosympathetic responses by comparing blood flow and vascular resistance in the forelimb and hindlimb during head-up tilt from the prone po...

BACKGROUND The cross-sectional morphology of the prosthetic knee is crucial to understanding patellar motion and quadriceps strength after total knee arthroplasty. However, few comparative evaluations of the cross-sectional morphology of the femoral trochlea have been performed in the native knee and currently available femoral implants, and the relationship between the trochlear anatomy of pro...

Tolerance to positive vertical acceleration (Gz) gravitational stress is reduced when positive Gz stress is preceded by exposure to hypogravity, which is called the "push-pull effect." The purpose of this study was to test the hypothesis that baroreceptor reflexes contribute to the push-pull effect by augmenting the magnitude of simulated hypogravity and thereby augmenting the stimulus to the b...

BACKGROUND prolonged head-up tilt testing and sublingual nitrate provocation are increasingly used in the diagnosis of neurocardiogenic syncope. However there are few data regarding the results of these tests in asymptomatic older subjects. OBJECTIVE to assess the responses to the prolonged head-up tilt test followed by sublingual glyceryl trinitrate provocation in asymptomatic subjects over ...

In patients with orthostatic intolerance, the mechanisms to maintain BP (blood pressure) fail. A physical counter-manoeuvre to postpone or even prevent orthostatic intolerance in these patients is leg crossing combined with muscle tensing. Although the central haemodynamic effects of physical counter-manoeuvres are well documented, not much is known about the peripheral haemodynamic events. The...

The purpose of this prospective randomised cross-over study was to measure peak expiratory flow rates during manual hyperinflation and to determine if the addition of a head-down tilt to physiotherapy treatment increased sputum production in patients who are intubated and ventilated. Twenty patients who were intubated, ventilated and haemodynamically stable were randomised to a sequence of phys...

A subclinical form of slipped capital femoral epiphysis (SCFE) can lead to subtle morphologic abnormalities, such as cam-type femoroacetabular impingement (FAI). Femoroacetabular impingement is a mechanical hip abnormality that typically affects young populations and leads to hip pain and premature osteoarthritis. Imaging is critical to diagnosis, whether by radiograph, magnetic resonance imagi...

We studied the difference in head-up tilt test responses between patients suffering from syncope who had hypertension and those who did not. A total of 338 consecutive patients with syncope underwent head-up tilt testing in our department from January 2003 to October 2004. Of these, 243 did not have hypertension (group A), whereas 95 did (group B). There were significant differences between the...

To investigate the effect of head roll tilt on the binocular coordination of ocular counterroll in non-human primates, we measured binocular ocular counterroll in two rhesus monkeys fixating a straight ahead target, while adopting different head roll tilt positions. We used two infrared cameras to take snapshots of the left and the right eye in order to measure the resulting ocular counterroll ...

BACKGROUND Clinical observations in patients with postural tachycardia syndrome (POTS) suggest abnormal sympathetic nervous system activity and a dysfunction of the norepinephrine (NE) transporter (NET). METHODS AND RESULTS We examined sympathetic nervous system responses to head-up tilt by combining NE plasma kinetics measurements and muscle sympathetic nerve activity recordings and by quant...