Nobuo Sakurai

Reaction times of movement preparation in patients with Parkinson's disease

We studied the onset of preparatory postural responses and subsequent voluntary movements by measuring soleus muscle activities in the standing position in 20 patients with Parkinsons disease. We measured the postural response in preparing to rise on tiptoe as the onset of the premotion silent period (PMSP). Our patients showed no delay when compared with age-matched healthy controls, but did show a significant delay in the onset of voluntary movement. The elongated PMSP (increased duration of the preparatory postural adjustments) was related to the severity of bradykinesia. Results indicate that the conventional reaction time is increased in patients with Parkinsons disease, even though there is no delay of central processing for the preparation of voluntary movements, and that there is bradykinesia of involuntary postural movements.

Treatment of postprandial hypotension with selective α1 and β1 adrenergic agonists

Abstract In order to treat postprandial hypotension (PPH), we orally administered a combination of denopamine (10 mg, a selective β1-adrenergic agonist) and midodrine-HCl (4 mg, a selective α1-adrenergic agonist) to eight patients with autonomic failure (AF) prior to and after eating. When the patients were given 75 g glucose with 225 ml water without drugs, blood pressure fell subsequently, cardiac output (CO) was unchanged, and vascular resistance of the lower legs (LVR) decreased. However, concomitant administration of denopamine and midodrine-HCl prevented PPH and increased CO and LVR. The portal blood flow was not indifferent to the drugs. A marked increase in heart rate after drug administration was seen in some patients with AF, which reflects the supersensitivity to denopamine. Combined oral administration of denopamine and midodrine-HCl is a safe and useful therapy for PPH in patients with AF.

Postprandial hypotension: hemodynamic differences between multiple system atrophy and peripheral autonomic neuropathy

To clarify the mechanism of postprandial hypotension (PPH), we performed hemodynamic investigation after oral glucose ingestion in ten patients with multiple system atrophy (MSA), three patients with peripheral autonomic neuropathy (PN) and 16 normal controls. Blood pressure (BP) and heart rate (HR) were measured with an automatic sphygmomanometer; cardiac out (CO) and lower leg blood flow (LBF) with impedance plethysmography; and portal blood flow (PBF) using a B-mode pulse Doppler. In normal subjects, BP, LBF and vascular resistance of the lower leg (LVR) were not changed, but HR slightly increased, and PBF and CO significantly increased after oral ingestion of 75 g glucose. In the patients with MSA, BP fell significantly 15 min after glucose ingestion, and HR and CO did not increase. PBF and LBF increased and LVR fell significantly. In PN patients, BP decreased at 15 min after glucose ingestion, but soon recovered. Increase of PBF and decrease of LVR in them were almost similar to those in the MSA group, and increase of CO was greater than that in the controls. These results suggest that both systemic vasodilatation (presumably due to gastrointestinal vasodilatatory peptides) and lack of compensatory increase of CO and LVR play important roles in PPH.

Combined effects of vibration and noise on palmar sweating in healthy subjects

SummaryThe combined effects of vibration and noise on palmar sweating were studied experimentally in healthy subjects. Ten subjects were exposed to vibration at an acceleration of 100 m·sec−2 root mean square at a frequency of 125 Hz, a noise level of 105 dB(A) at a frequency of 1000 Hz and both stimuli together. Vibration was applied to the right hand and noise to both ears from headphones. Palmar sweating was measured by the ventilated capsule method. Vibration caused a marked increase in palmar sweating of the right hand directly exposed to vibration and also of the left hand not exposed to vibration. Simultaneous vibration and noise caused a greater increase in palmar sweating than by each of the factors separately. The combined effects tended to be greater in subjects who were more susceptible to vibration or noise.