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Biomedical subjects

J D Stewart

Publications and source records attributed to J D Stewart.

At least 109 records · Page 6Linked to original sources
PubMed1975

Vestibular-ocular accommodation reflex in man.

Stimulation of the vestibular system by angular acceleration produces widespread sensory and motor effects. The present study was designed to study a motor effect which has not been reported in the literature, i.e., the influence of rotary acceleration of the body on ocular accommodation. The accommodation of 10 young men was recorded before and after a high-level deceleration to zero velocity following 30 s of rotation. Accommodation was recorded continuously on an infrared optometer for 110 s under two conditions; while the subjects observed a target set at the far point, and while they viewed the same target through a 0.3-mm pinhole. Stimulation by high-level rotary deceleration produced positive accommodation or a pseudomyopia under both conditions, but the positive accommodation was substantially greater and lasted much longer during fixation through the pinhole. It is hypothesized that this increase in accommodation is a result of a vestibular-ocular accommodation reflex.

Accommodation, Ocular↗
PubMed1975

Choice reaction time to visual motion during prolonged rotary motion in airline pilots.

Thirteen airline pilots were studied to determine the effect of preceding rotary accelerations on the choice reaction time to the horizontal acceleration of a vertical line on a cathode-ray tube. On each trial, one of three levels of ratary and visual acceleration was presented with the ratary stimulus preceding the visual by one of seven periods. The two accelerations were always equal and were presented in the same or opposite directions. The reaction time was found to increase with increases in the time the rotary acceleration preceded the visual acceleration, and to decrease with increased levels of visual and rotary acceleration. The reaction time was found to be shorter when the accelerations were in the same direction than when they were in opposite directions. These results suggest that these findings are a special case of general effect that the authors have termed "gyrovisual modulation."

Acceleration↗
PubMed1973

Quantitative assessment of hemadsorption by myxoviruses: anti-immunoglobulin G hemadsorption-inhibition test.

A quantitative hemadsorption-inhibition test was developed to estimate myxovirus serum antibodies within 24 h by determining the serum dilution inhibiting hemadsorption in 50% of the infected cells. The test depends on the interactions of virus-infected cell monolayers with antiviral serum and of the resultant complexes with antiimmunoglobulin G serum. The incorporation of species-specific anti-immunoglobulin G serum into the test significantly increased sensitivity.

Animals↗