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Biomedical subjects

G Aschan

Publications and source records attributed to G Aschan.

13 recordsLinked to original sources
PubMed1979

The influence of trichloroethylene and related drugs on the vestibular system.

A previously described experimental model for studying the effect of industrial solvents on the vestibular system of rabbits has been applied to trichloroethylene. Estimation of trichloroethylene and its metabolites in blood and cerebrospinal fluid was performed by gas chromatography. Vestibular function was studied by recording nystagmus, induced by positional changes or accelerated rotation. At blood levels of trichloroethylene above 30 p.p.m. "positional nystagmus" develops. Two metabolites of trichloroethylene, chloral hydrate and trichloroethanol, which are known as central nervous system (CNS) depressants, did not induce this abnormal nystagmus. However, alpha-chloralose, a derivative of chloral hydrate, induced positional nystagmus and also a markedly exaggerated nystagmus developed during rotatory acceleration. It is suggested that solvents like trichloroethylene elicit vestibular disturbances by stimulation of central subcortical vestibulo-oculomotor connections. The stimulation may be caused by a blockage of inhibitory systems.

Animals↗
PubMed1979

On the mechanism of vestibular disturbances caused by industrial solvents.

The industrial solvents xylene, styrene, trichloroethylene and methylchloroform administered to rabbits caused a positional nystagmus and disturbances in the nystagmus response to rotatory acceleration. The positional nystagmus had a beat direction the opposite to positional alcohol nystagmus, which was in similar experiments elicited by methanol, ethanol and propanol. The three alcohols needed a ten times higher blood concentration to cause a nystagmus than the solvents did.

1-Propanol↗
PubMed1979

Hyposensitization in allergic seasonal rhinitis as evaluated by rhinomanometry.

Hyposensitization with Allpyral extracts was performed in 38 patients suffering from seasonal allergic rhinitis. An objective evaluation of the clinical course was obtained by rhinomanometry. After one year of hyposensitization therapy, 55% of the patients (21 out of 38) showed an improvement, and after the 3-year follow-up this figure had increased to 76% (19 out of 25 patients continuing with the treatment for this period). For the patients' subjective appraisal of the therapy the respective figures were 76 and 92%.

Adolescent↗
PubMed1978

Exposure of rabbits to styrene. Electronystagmographic findings correlated to the styrene level in blood and cerebrospinal fluid.

Objective methods for critically evaluating the toxic effect of industrial solvents are highly desirable. As many of these solvents are suspected to cause vertigo, an animal experimental model was set up for studying the effects of solvents on the vestibular systems. The vestibular function was studied by registration of involuntary eye movements--nystagmus--which are elicited via central vestibulo-oculomotor connections. During exposure to styrene a so-called positional nystagmus was demonstrated that indicated vestibular disturbances. Nystagmus is normally elicited by rotatory acceleration. During exposure to styrene the direction of this rotatory nystagmus was reversed. The incidence of the positional nystagmus correlated well with the blood level of the solvent, measured by gas chromatography. Kinetic studies also demonstrated a rapid equilibration between the level of the solvent in arterial blood and cerebrospinal fluid, and therefore suggested that estimation of the arterial level reliably indicates the level in the central nervous system.

Animals↗
PubMed1978

Hyposensitization in allergic rhinitis--a comparison of aqueous extracts and Allpyral by means of rhinomanometry.

Fifty-six patients with seasonal allergic rhinitis were hyposensitized with aqueous extracts (23 patients) and Allpyral extracts (33 patients). The clinical course was appraised objectively on the basis of rhinomanometry findings at examinations performed before hyposensitization and one year later. There was no essential difference between the two groups of patients as regards the relief of symptoms. A reduction of nasal congestion was recorded in 54 and 58% of the patients, respectively. Complications were less severe and less frequent in the Allpyral group.

Adolescent↗
PubMedDate not supplied

Electronystagmographic and gaschromatographic studies in rabbits.

Complaints of vertigo from people who are exposed to industrial solvents have focused interest on their toxic effect on the nervous system. In order to evaluate the influence of an organic solvent, xylene, on the mammalian vestibular system, a series of rabbit experiments were performed. To achieve a constant concentration, the xylene was infused as a lipid emulsion. Blood concentrations were estimated by gas chromatography. Electronystagmography in darkness revealed that at blood xylene concentrations of 30 ppm all rabbits had a positional nystagmus. The beat direction was the opposite of positional alcohol nystagmus. Another difference between the alcohol and the xylene reaction was that rotatory nystagmus responses were exaggerated. The relations between the present findings and the reactions and blood concentrations in people exposed to industrial solvents are discussed.

Aerosols↗
PubMedDate not supplied

Limb input to the cat vestibular nuclei.

The input from fore- and hindlimbs to the vestibular nuclear complex (VNC) was investigated in awake cats. Electrical stimulus was given to the sciatic, radial and vestibular nerves bilaterally and single unit responses were recorded in the VNC with extracellular technique. The position of the microelectrode was histologically confirmed. All four major vestibular nuclei received fore- as well as hindlimb input. Forty per cent of the neurons with limb input also received vestibular afferents. No major distinguishing features appeared between the different nuclei with regard to response characteristics. Certain differences in laterality of response, quantitative fore-hindlimb ratio and somatosensory-labyrinthine convergence were observed however. Response latencies to sciatic and radial nerve stimuli always exceeded a 3 msec and were grouped around 8 and 16 msec. A third population of vestibular neurons had latencies over 20 msec. Both excitatory and inhibitory responses were recorded, with the latter not always following an activation. The findings illustrate the complex nature of the ascending pathway to the VNC and the integrative properties of this complex.

Action Potentials↗
PubMedDate not supplied

Improved lymphocyte ectoenzyme function during normal pregnancy.

During normal pregnancy, the 5'-nucleotidase (AMPase) enzyme activity on the circulating human lymphocyte pellet has been found to be increased significantly (p less than 0.001) in comparison with that of healthy normal persons employed as controls. The increased lymphocyte activity diminished rapidly subsequent to parturition. The enzyme activity on lymphocytes purified from umbilical cord blood was not increased. Acute viral infections induced a transient reduction in the enzyme activity. Further studies of this natural defence mechanism are in progress.

Female↗