Biomedical subjects
Publications and source records attributed to E C Jansen.
In a double-blind cross-over study, the influence of propranolol on postural stability was investigated in 7 normals. The postural stability was measured by a computer-assisted quantitative Romberg test. A dose of 10 mg propranolol administered intravenously resulted in an impaired postural stability, with a delay of about half an hour. This delay could be responsible for the missing correlation between the sway and plasma-propranolol.
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Postural stability was measured in 100 healthy people by a quantitative, computer calculated Romberg's test. The persons were aged 20-69 years, and a table of normal ranges is provided. Older men are found to have higher sway figures than young men, while this was not significant in the group of women. In a second part of the study the reproducibility of the method was studied in 10 healthy people. Sway was measured twice a day during 5 consecutive days of work. No significant alterations in the sway measurements were found. The individual variation coefficients ranged from 11-29% (mean value: 18%). By the present study it is concluded that the quantitative Romberg's test is a reasonable way of measuring postural stability.
Forty normal persons had their gait tested using an instrumented treadmill. All were tested at the same speed of gait. The temporal factors of gait, the ataxia, and the external work of the gait were all calculated from the ground reaction forces. Ten women and ten men 20-29 years and ten women and ten men aged 60-69 were tested. The study demonstrated a constant pattern of gait independent of age and sex.
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Five patients with essential tremor were treated with increasing daily doses of propranolol. Tremor intensity was assessed after each propranolol dose had been given daily for a period of at least seven days. The evaluation was made 12 to 15 hours after the last propranolol ingestion. It included a semiquantitative clinical tremor evaluation and quantitative registration with an accelerometer. Electronic integration of the accelerometer curves gave an arbitrary measure of tremor intensity. Plasma propranolol concentration was determined at each tremor measurement. The reduction in tremor correlated with increasing propranolol doses, whereas plasma propranolol concentrations varied widely among individuals and could not be correlated with tremor reduction. Most of the patients had considerable diminution in tremor at low propranolol doses, often with an unmeasurable plasma propranolol concentration. Determination of plasma concentrations has little value in long-term treatment of essential tremor with propranolol. The dosage can be sufficiently guided by clinical evaluation of effect.
A total of 16 normal, medium sized persons were given 20 g of alcohol every hour for 4-5 h. This yielded blood alcohol concentrations between 0.1 mg/ml and 1.7 mg/ml (0.1-1.7%) during the 4-5 h of testing. By use of a computer-assisted force plate system, objective measurements of postural imbalance were performed each hour. An increasing postural imbalance was found at blood alcohol concentrations above 0.6 mg/ml (0.6%). The results illustrate the risk of intake of alcohol by people highly dependent on a safe standing position.
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