| 1. |
- Möller, Claes, 1950-, et al.
(författare)
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Otoneurological findings in workers exposed to styrene
- 1990
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Ingår i: Scandinavian Journal of Work, Environment and Health. - : Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; 16:3, s. 189-194
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Tidskriftsartikel (refereegranskat)abstract
- An otoneurological test battery was administered to 18 workers with long-term exposure (6-15 years) to styrene at levels well below the current Swedish limit (110 mg/m3). The results were compared with those of a reference group. Disturbances were found in the central auditory pathways of seven workers. Tests reflecting central processing of impulses from different sensory equilibrium organs were abnormal for 16 workers. The most relevant tests seemed to be static posturography and the rotatory visual suppression test. In the posturography the styrene group had a significantly larger sway area than the reference group. In the visual suppression test, the styrene workers displayed a significantly poorer ability to suppress vestibular nystagmus than the reference group. It was concluded that styrene exposure in industrial environments at moderate or low levels causes central nervous system disturbances which are not always diagnosable with psychometric tests but can be apparent in special otoneurological tests.
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| 2. |
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| 3. |
- Niklasson, Magnus, et al.
(författare)
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Effects of GABAB activation and inhibition on vestibulo-ocular and optokinetic responses in the pigmented rat
- 1994
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Ingår i: Brain Research. - : Elsevier. - 0006-8993 .- 1872-6240. ; 649:1-2, s. 151-158
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Tidskriftsartikel (refereegranskat)abstract
- The effects of the GABAB agonist baclofen and the GABAB antagonist CGP 35348, given separately or simultaneously, on the central vestibular system of pigmented rats have been evaluated. Drugs were administered either intramuscularly or intracerebroventricularly. Eye movements were recorded during vestibular, optokinetic and combined visual-vestibular stimulation. Activation of the GABAB receptors by baclofen caused a dose related disturbance of the system, manifested by (1) a decrease of the optokinetic gain, (2) a reduced ability to suppress nystagmus during conflicting vestibular and visual input, and (3) a disability to maintain the eccentric eye position upon a spontaneous saccade. All these effects could be inhibited in a dose-dependent fashion by CGP 35348, suggesting that the findings are specifically related to the GABAB receptor. Given separately, the antagonist did not affect the mentioned parameters. During horizontal acceleratory/deceleratory stimulation in darkness baclofen caused a biphasic pattern in the dose-response curves. Small amounts of baclofen caused an increase of the gain and of the duration of poststimulatory nystagmus, while high doses had a depressive action on the same parameters. The stimulating effect of baclofen could be inhibited or even reversed by CGP 35348, which has a depressive effect per se, similar to the effects of baclofen given in the upper range of doses.
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| 4. |
- Niklasson, Magnus, et al.
(författare)
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Effects of toluene, styrene, trichloroethylene, and trichloroethane on the vestibulo- and opto-oculo motor system in rats
- 1993
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Ingår i: Neurotoxicology and Teratology. - 0892-0362 .- 1872-9738. ; 15:5, s. 327-334
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Tidskriftsartikel (refereegranskat)abstract
- The acute effects of inhalation of four solvents on the central vestibular system of rats were analyzed by recording eye movements upon different stimuli. The dose-response relationship was investigated. Optokinetic stimulation was obtained by placing the animals in front of a surrounding visual pattern, moving at different velocities. The slow-phase eye velocity (SPV) of nystagmus was calculated and divided by the stimulus velocity, giving the gain. All the solvents caused a decrease of the gain. Vestibular stimulation was performed on a turntable by an angular acceleration/deceleration in darkness. The SPV and the duration of the post-stimulatory nystagmus were calculated. The shape of the SPV dose-response curves differed among the four solvents. Toluene, styrene, and trichloroethylene prolonged the duration of nystagmus while trichloroethane did not. A conflicting vestibular and optokinetic stimulation was performed by an angular acceleration/deceleration with a surrounding visual pattern moving with the turntable. All solvents decreased the ability to cancel nystagmus, elicited by vestibular stimulation in conflict with a visual input. Quick movements of the eyes, saccades, were elicited by tactile stimulation. Toluene, styrene, and trichloroethylene changed the generation of the saccades while trichloroethane did not. Most of the findings indicate a common site of action in the central vestibular system, viz., the cerebellar-vestibular circuit. However, within this domain, there are evident differences in the effects among the solvents. This finding, together with previous results obtained in other experimental models of the central nervous system (CNS), suggest that different solvents should be considered as individual compounds. While the current results are consistent with the notion that solvents affect cerebellar-vestibular function, they also demonstrate differences on selected components of this system which may be of concern.
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| 5. |
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| 6. |
- Niklasson, Magnus, et al.
(författare)
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The influence of visual and somatosensory input on the vestibulo-oculomotor reflex of pigmented rats
- 1991
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Ingår i: Journal of Vestibular Research-Equilibrium & Orientation. - 0957-4271 .- 1878-6464. ; 1:3, s. 251-262
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Tidskriftsartikel (refereegranskat)abstract
- Eye movements were recorded in the pigmented rat during vestibular, optokinetic and combined visual-vestibular stimulation. The dominant time constant in pigmented rats, tested during angular vestibular stimulation in darkness, is about two times longer than the cupular time constant. The gain and the duration of nystagmus, achieved by angular vestibular stimulation, can be enhanced by visual impulses. This is most evident during an optokinetic temporonasal stimulation, but is also seen with a nasotemporal stimulation. A mere optokinetic monocular stimulation without a synchronous vestibular excitation causes nystagmus only when the stimuli has a temporonasal direction. The duration of nystagmus, achieved by angular vestibular stimulation, is prolonged by disturbances of the neck proprioceptive system. This is more evident during a simultaneous visual input than in darkness. The ability to cancel nystagmus during conflicting vestibular and optokinetic impulses is well developed in the pigmented rat.
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| 7. |
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| 9. |
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| 10. |
- Nylén, Per, et al.
(författare)
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Vestibular-oculomotor, opto-oculomotor and visual function in the rat after long-term inhalation exposure to toluene
- 1991
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Ingår i: Acta Oto-Laryngologica. - : Informa Healthcare. - 0001-6489 .- 1651-2251. ; 111:1, s. 36-43
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Tidskriftsartikel (refereegranskat)abstract
- Pigmented rats were exposed to toluene (1000 ppm, 21 h/day) for 6 or 11 weeks. The function of the vestibulo- and opto-oculomotor systems was tested one month after the end of the exposure by recording of nystagmus, induced by vestibular or optokinetic stimuli. The eye movements were recorded by a magnetic search coil technique. The optokinetic gain in the exposed animals was reduced compared to a control group. There was also a slight reduction in gain during sinusoidal oscillatory vestibular stimulation. No effect of the toluene exposure on the gain or duration of nystagmus during acceleratory or deceleratory rotatory stimulation was demonstrated, nor was there any change in the duration of the optokinetic after-nystagmus. The function of the visual system was tested 2 to 5 days after exposure by recording the electroretinogram and the visual evoked response. The conduction velocity in peripheral nerve was also measured. No effect of the toluene exposure on these variables was seen. The results indicate that long-term inhalation of toluene causes a long-lasting, possibly permanent, lesion within the vestibulo-cerebellum. They gave no evidence that such exposure affects peripheral vestibular or visual function.
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