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Biomedical subjects

J R Stott

Publications and source records attributed to J R Stott.

At least 19 recordsLinked to original sources
PubMed2000

Comparison of the neurokinin-1 antagonist GR205171, alone and in combination with the 5-HT3 antagonist ondansetron, hyoscine and placebo in the prevention of motion-induced nausea in man.

AIMS: In man a neurokinin-1 (NK1) receptor antagonist has previously been shown to be ineffective in the prevention of motion-induced nausea. The antiemetic efficacy of NK1 receptor antagonists against chemotherapy-induced emesis is, however, enhanced when combined with a 5-HT3 receptor antagonist. Hence the efficacy of the NK1 antagonist GR205171 in combination with the 5-HT3 antagonist ondansetron (Zofrantrade mark) was assessed in motion-induced nausea. METHODS: GR205171 25 mg i.v., with and without concomitant administration of ondansetron 8 mg i.v., and hyoscine hydrobromide 0. 6 mg orally (positive control) were compared with placebo in a model of motion-induced nausea. The study was performed to a four-period, randomized, balanced, double-blind, crossover design in 16 healthy subjects. The end-point was the exposure to the motion stimulus required to produce moderate nausea in the subjects. RESULTS: The motion stimulus required to produce moderate nausea was significantly greater for the positive control than placebo (P < 0. 001). There was no significant difference between either GR205171 or GR205171 plus ondansetron and placebo (P = 0.648 and 0.342, respectively). CONCLUSIONS: The enhancement of NK1 receptor antagonist antiemetic activity through combination with a 5-HT3 receptor antagonist is not replicated in motion-induced nausea.

Adolescent↗
PubMed1997

Comparison of the effects of a selective muscarinic receptor antagonist and hyoscine (scopolamine) on motion sickness, skin conductance and heart rate.

AIMS: Hyoscine (scopolamine), which is effective in the prophylaxis of motion sickness, shows similar binding affinities to all of the five known muscarinic receptor sub-types. The effectiveness of hyoscine was compared with zamifenacin (UK-76654), which binds selectively to the muscarinic M3 and m5 receptors. METHODS: Eighteen subjects received hyoscine hydrobromide 0.6 mg, zamifenacin 20 mg, or placebo (double-blind cross-over design). Sessions were 1 week apart and the drug (oral) was given 90 min prior to a motion sickness test. Motion sickness was elicited by cross-coupled stimulation on a turntable. The rotational velocity was incremented by 2 degrees s-1 every 30 s, and a sequence (seq) of eight head movements of 45 degrees was completed every 30 s. Motion tolerance was assessed as the number of sequences of head movement required to achieve moderate nausea. Pulse rate was recorded before and at 1 and 2 h after drug administration. Skin conductance activity in the frequency band 0.005-0.48 Hz, an index of sweat gland activity, was measured using Ag/AgCl electrodes on the palmar surfaces of fingers and across the forehead. RESULTS: Both zamifenacin and hyoscine produced an increase in tolerance to the motion challenge (P < 0.01) with no significant difference between the two drugs (5.0 +/- 1.6 vs 5.7 +/- 1.6 seqs. respectively, mean +/- s.e.mean). Compared with placebo or zamifenacin, pulse rate fell following hyoscine administration (9 beats min-1, P < 0.01). Skin conductance was reduced following hyoscine compared with zamifenacin or placebo (P < 0.001). CONCLUSIONS: These results suggest that compounds with selective M3 and/or m5 antagonism possess activity against motion sickness. Antagonism at these receptors may be the basis of the anti-motion sickness action of hyoscine.

Adult↗
PubMed1997

Frequency effect of 0.35-1.0 Hz horizontal translational oscillation on motion sickness and the somatogravic illusion.

BACKGROUND: Low frequency translational oscillation can provoke motion sickness in land vehicles, ships and aircraft. HYPOTHESIS: Nauseogenicity should decrease towards the higher frequencies. METHODS: Some 12 subjects were exposed to horizontal sinusoidal motion (3.6 m.s-2 peak) at four different frequencies 0.35, 0.50, 0.70, and 1.00 Hz, at 1-week intervals, latin square order. Subjects were seated in the upright position; motion was through the head-body X-axis. Motion was stopped (motion endpoint) at moderate nausea or after 30 min. RESULTS: The proportion of subjects experiencing moderate nausea decreased towards the higher frequency: 9/12 at 0.35 Hz, 3/12 at 0.50 Hz, 0/12 at 0.70 Hz, and 2/12 at 1.00 Hz. The mean time to motion endpoint increased significantly (p < 0.001) towards the higher frequency: 17.4 min 0.35 Hz; 26.0 min 0.50 Hz; 30 min 0.70 Hz; 28.3 min 1.00 Hz. Differences between frequencies were significant (0.001 < p < 0.05) except for 0.70 Hz to 1.00 Hz. At all frequencies tested, horizontal stimuli were more nauseogenic than predicted by mathematical models based on the frequency and intensity of vertical oscillation. Somatogravic illusion (SGI) was reported by 9/12 subjects (mean illusory tilt angles 15.6 degrees forward, 14.1 degrees back). SGI tended to diminish at the higher frequencies, but there was no relationship between SGI and motion sickness. CONCLUSIONS: These results confirm previous findings (9), and furthermore indicate that horizontal X-axis translational oscillation has greatly reduced nauseogenic potential at frequencies greater than 0.5 Hz. A mathematical model is proposed to predict motion sickness intensity and incidence due to this stimulus, which may also be applicable to equivalent Y-axis motion.

Adult↗
PubMed1996

Perception of direction of visual motion. II. Influence of linear body acceleration.

We investigated whether linear whole-body acceleration along the interaural y-axis influenced the concurrent perception of visual motion direction as has been shown for angular accelerations. A sled running on air bearings along a 7.5-m track was used to accelerate 18 subjects at two different linear accelerations. These young, healthy volunteers, aged 25.50 +/- 7.38 years, used a joystick to indicate whether or not they perceived visual motion to the left within a random-dot kinematogram continuously presented on a monitor moving with them. The percentage of coherently leftward moving pixels presented for a 640-ms period during acceleration was adjusted according to a Modified Binary Search (MOBS) procedure. Six conditions were tested, two acceleration levels of 1 and 2 m/s2 to both left and right with, at the higher acceleration, two different times of visual motion presentation. Conditions were sequenced by means of a 6 x 6 Latin square balanced for order and carry over. A MANOVA did not show any statistically significant effects either for the independent variables acceleration, velocity, and direction of motion of the sled or for their interactions. The results obtained are in clear contrast to those obtained under rotatory stimulation. We conclude that the otolithic contribution to vestibular-visual motion processing is negligible.

Acceleration↗
PubMed1995

Effect of sickness severity on habituation to repeated motion challenges in aircrew referred for airsickness treatment.

The aim of this study was to determine whether varying the predetermined malaise level at which provocative motion challenges were stopped would affect the habituation rate. At the rate of 2 per day, 21 motion challenges were delivered, stopping either at initial symptoms or at moderate nausea, on a cross-over design randomized between subjects (n = 20). The cross-coupled motion challenge had an incrementing profile of rotational velocity from 2-90 degrees.s-1 in steps of 2 degrees.s-1 every 30 s, with 8 head movements per 30 s, of approximately 45 degrees. The number of head movements tolerated before the onset of nausea increased over the 21 challenges, but the effects of the treatment variation on habituation were not significant. The number of motion challenges, rather than the severity of malaise level achieved, was the more important factor determining habituation.

Adaptation, Physiological↗
PubMed1995

The effects of motion direction, body axis, and posture on motion sickness induced by low frequency linear oscillation.

BACKGROUND: A recent experiment demonstrated that low frequency linear oscillation through the Z-axis of the body was more nauseogenic when applied in the vertical direction, with subjects seated upright, than in the horizontal direction, with subjects supine. HYPOTHESIS: The nauseogenicity of low frequency linear oscillatory motion is dependent on direction of motion with respect to the gravity vector, orientation of body axis with respect to motion, and body posture. METHODS: The following conditions were compared: A) seated upright, with horizontal motion, X-axis; B) seated upright, with vertical motion, Z-axis; and C) supine, with vertical motion, X-axis. Sinusoidal motion at 0.35 Hz, 3.6 m.s-2 peak was used in all conditions. Two experiments were performed. In Experiment 1 subjects (n = 28) were exposed to conditions A and B. In Experiment 2 subjects (n = 12) were exposed to conditions A, B and C. RESULTS: Horizontal motion (condition A) was found to be twice as nauseogenic (p < 0.05 to p < 0.0001) as vertical motion (condition B), but there was no difference in nauseogenicity between upright and supine postures for vertical motion (condition B vs. C). Mean motion exposure times to achieve moderate nausea were: Experiment 1: A) 9.0 min.; B) 22.4 min.; Experiment 2: A) 15.3 min.; B) 27.1 min.; C) 22.5 min. CONCLUSIONS: These results, taken together with those of the previous experiment, suggest that upright vs. supine body posture and stimulation through X- vs. Z-axis, both enhance the nauseogenicity of low frequency linear oscillation, these effects are additive, but that motion direction with respect to the gravity vector (horizontal vs. vertical) is a less important factor.

Adult↗
PubMed1994

In flight verification of the inversion illusion.

Pilots' sensations of orientation while pushing over (bunting) are inconsistent. We flew 13 aircrew or naive subjects individually in a Hawk or Hunter jet training aircraft. With sun visor down and eyes closed, each was asked to report what the aircraft was doing. After unaccelerated level flight for 30 s, the aircraft was accelerated in level flight from 200 to 250 kts at +0.15 to +0.25 Gx, and gently pulled into a stable 250-kt, 3000 ft/min climb. After 30 s, it was pushed to -1 G during 3 s. Minus 1 G was then held for a further 3 s. Of 30 maneuvers, 14 produced sensations of inversion in 9 of 13 subjects. Two subjects reported feet-up rotation to the inverted; one felt a rotation of indeterminate direction; five felt sudden inversion. This illusion was experienced by 3/3 naive non-pilots, 6/8 pilots, and 0/2 test pilots. We conclude that the "inversion illusion" exists, and that the postulated sensation of backward rotation is often not perceived.

Acceleration↗
PubMed1989

The effect on motion sickness and oculomotor function of GR 38032F, a 5-HT3-receptor antagonist with anti-emetic properties.

1. The 5-hydroxytryptamine (5-HT3) receptor antagonist, GR 38032F, which possesses potent anti-emetic properties in vomiting induced by cancer chemotherapeutic drugs, has been tested to determine its value in the prophylaxis of motion sickness induced by cross-coupled stimulation. The double-blind trial compared GR 38032F with both a placebo (lactose) and with hyoscine. In addition, studies of ocular pursuit and saccadic eye movements were carried out following the administration of each drug. 2. The prophylactic effect of GR 38032F on motion-induced nausea was indistinguishable from that of placebo, whereas following hyoscine subjects showed a highly significant (P less than 0.001) increase in tolerance to cross-coupled stimulation. Tests of oculomotor function showed no effect on saccadic eye movement from either drug. However, both drugs produced a significant (P less than 0.05) though small reduction in eye velocity gain during pursuit eye movement. 3. These findings suggest that the 5-HT3 receptor is not involved in the neural pathways that bring about motion sickness, but that it may have a role in the control of ocular pursuit. The absence of an anti-motion sickness effect from a drug that is effective in the treatment of vomiting induced by cancer chemotherapy serves to emphasize that different neural mechanisms are involved in the generation of motion sickness.

Adolescent↗
PubMed1988

Selective vibration sensing: a new concept for activity-sensing rate-responsive pacing.

A clinically available model of an activity-sensing, rate-responsive pacemaker (Activitrax, Medtronic) utilizes body vibration during exercise as an indicator of the need for a rate increase. Although having the advantage of rapid onset of rate response, this system lacks specificity and the rate response does not closely correlate with the level of exertion. In addition, this pacemaker is susceptible to the effects of extraneous vibration. In this study involving 20 normal subjects fitted with an external Activitrax pacemaker, the rate responses to a variety of exercises were studied and were compared with the corresponding sinus rates. The vibration generated at the level of the pacemaker was also measured by accelerometers in three axes. Only a fair correlation (r = 0.51) was achieved between the pacemaker rate and the sinus rate. The total root mean square value of acceleration in either the anteroposterior or the vertical axes was found to have a better correlation (r = 0.8). As the main accelerations during physical activities were in the lower frequency range (0.1-4 Hz), a low-pass filter was used to reduce the influence of extraneous vibration. Selective sensing of the acceleration level may be usefully implemented in an algorithm for activity pacing.

Adult↗
PubMed1986

Thresholds for the detection of the direction of whole-body, linear movement in the horizontal plane.

Thresholds for the detection (at p = 0.67 correct) of the direction of discrete linear movements in the horizontal plane, having a cosine bell velocity trajectory and duration of 3 s, were determined in 24 subjects. Thresholds in the Z body axis (mean 0.154 m X s-2) were significantly higher than thresholds for movement in the X (mean 0.063 m X s-2) and Y (mean 0.057 m X s-2) body axes. In 8 subjects, X axis acceleration threshold was found to increase as a monotonic function of stimulus duration over the range 0.98 to 6.96 s and exhibited similar frequency-dependent characteristics to thresholds for the detection of continuous oscillatory stimuli. This finding implies that the sensory system mediating the transduction and perception of liminal, whole-body linear movement is sensitive to a combination of the acceleration and rate change of acceleration (jerk) of the motion stimulus, and has similar dynamics to the "irregular" sensory receptors of the otolith organs.

Analysis of Variance↗
PubMed1985

The desensitisation of chronically motion sick aircrew in the Royal Air Force.

The RAF Motion Sickness Desensitisation Programme has been in operation since 1966 and to January 1984 151 aircrew have been treated. The programme consists of a ground phase of treatment and a flying phase. Since January 1981 both phases have been located at Farnborough. Additional motion stimuli have been incorporated into the ground phase. The flying phase, which was previously carried out in a basic jet trainer, is now carried out in a high performance aircraft, the Hunter T7. Comparison of the results of follow-up for the period 1981-83 with those for 1974-80 indicates an improvement in overall success rate and shows a significant increase in the number that progress to fly in the demanding motion environment of fast jets.

Aerospace Medicine↗
PubMed1984

The vertical vestibulo-ocular reflex and ocular resonance.

A technique is described for the measurement of retinal image motion under conditions of forced angular vibration of the head in pitch at frequencies between 10 and 100 Hz. The experimental technique has been used in nine normal subjects, and in two subjects with vestibular dysfunction; one with unilateral, the other with bilateral deficit. Eye movements compensatory in phase were recorded at frequencies between 10 and 25 Hz in all normal subjects. The ratio of angular retinal image motion to angular head motion (ocular gain) over these frequencies was in the range 0.82-0.94. When the head was vibrated at frequencies above 30 Hz angular motion of the retinal image exceeded that of the head and showed progressive phase delay. Ocular gain reached a peak of 3.0 at 70 Hz and a less clearly defined peak of 1.3 at about 35 Hz. These findings are suggestive of mechanical resonances within the orbit, possibly involving intra-ocular structures.

Adolescent↗
PubMed1981

The mechanical properties of bone in osteoporosis.

Specimens of femoral cortical bone from normal subjects and from patients with osteoporosis were mechanically tested in tension to destruction. The osteoporotic bone showed less strength and less stiffness than the normal bone; these reductions are related to the increased cavity area in osteoporosis. Further, the osteoporotic bone is not able to absorb as much energy before fracture as the normal bone; but this difference is not related to changes in cavity area.

Aged↗
PubMed1979

The compressive strength of lumbar vertebrae.

Values for the compressive breaking load of lumbar vertebrae at physiological strain rates show enormous scatter across the population, ranging from 0.8 kN to nearly 16 kN. Increase in strength was found at faster strain rates, but differences in compressive strength between upper and lower lumbar vertebrae were not significant. Hydraulic strengthening does not appear to contribute to the compressive strength at the strain rates studied.

Adolescent↗