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Biomedical subjects

P Strauss

Publications and source records attributed to P Strauss.

At least 19 recordsLinked to original sources
PubMed1992

A health survey of toll booth workers.

The prevalence of respiratory and other health problems in a cohort of highway toll booth workers was surveyed by mailed questionnaire. In a low proportion of respondents (43.2%), a high prevalence of central nervous system complaints (headaches, irritability, or anxiety, and unusual tiredness), mucous membrane irritation (eye irritation, nasal congestion, and dry throat), and musculoskeletal problems (joint and back pains) was found. We believe these symptoms are reflective of the acute irritant and central nervous system effects of exposure to motor vehicle exhaust. The musculoskeletal complaints are likely the result of bending, reaching, and leaning out of the toll booth. The need for in-depth evaluation of the ventilation systems and the ergonomic and job stressors of work at toll booths is suggested by these results.

Adult↗
PubMed1990

Asbestos bodies in bronchoalveolar lavage fluids of brake lining and asbestos cement workers.

Asbestos body (AB) concentrations in bronchoalveolar lavage samples of 15 brake lining (BL) workers exposed only to chrysotile have been determined and compared with those from 44 asbestos cement (AC) workers extensively exposed to amphiboles. The mean AB concentrations (263 +/- 802 and 842 +/- 2086 AB/ml respectively) for those groups did not differ significantly but were much higher than those found in control groups. Analytical electron microscopy of asbestos body cores showed that in the BL group 95.6% were chrysotile fibres whereas in the AC group amphiboles accounted for 93.1%. The size characteristics of the central fibres differed for chrysotile and amphibole AB, the former being shorter and thinner. Examination of repeated bronchoalveolar lavage samples showed that the mechanisms of clearance of chrysotile fibres do not affect AB concentration for at least 10 months after cessation of exposure. It thus appears that routine counting of ABs in BAL allows the assessment of current or recent occupational exposures to asbestos. Exposures to chrysotile lead to AB concentrations comparable with those encountered in exposures to amphiboles.

Asbestos↗
PubMed1990

[The effect of gamma-aminobutyric acid at the somatic and dendritic level in Purkinje cells in the cerebellum of the frog in vitro].

The effect of gamma-aminobutyric acid (GABA) on its receptors localized on the somatic and dendritic membrane of Purkinje cells was tested on the isolated cerebellum of the frog. The action of GABA was found to be different in the two zones studied. On the membrane of the cell bodies GABA inhibited the overall synaptic potential and spontaneous activity by a mechanism dependent on increased Cl- conductivity resulting in hyperpolarization of the somatic membrane. On the dendritic membrane the inhibitory effect of GABA on the spontaneous activity of dendrites was only minimal and shortlasting. At intradendritic recording a depolarizing effect of GABA was observed whose mechanism is so far unknown.

Action Potentials↗
PubMed1988

Electrophysiological properties of the isolated vestibulocerebellar complex of the frog in vitro.

Parameters of the electrical activity of the isolated vestibulocerebellar complex of the frog were studied under in vitro conditions. In the region of the vestibular nucleus (nc. VIII), in the presence of stimulation of the stato-acoustic nerve (n. VIII), responses from efferent vestibular neurones and from unidentified (probably vestibulospinal) neurones were recorded. The latent periods of their excitatory postsynaptic potentials (EPSPs, 1.4-2.2 ms) were indicative of mono- and disynaptic connection. Inhibitory postsynaptic potentials (IPSPs) were also observed. Stimulation of the auricular lobe of the cerebellum evoked monosynaptic IPSPs, an EPSP-IPSP complex or pure EPSPs in nc. VIII, the latter probably by way of collaterals to the cerebellum. The inhibitory character of the effect of efferents from the cerebellum to the neurones of nc. VIII was demonstrated in the focal synaptic potential and in spontaneous and evoked unit activity. If n. VIII was stimulated, both focal and unit extra- and intracellular responses characteristic of activation of the Purkinje cells by mossy (MF) or climbing (CF) afferent fibres were recorded in the cerebellar cortex. The electrophysiological picture indicates that both synaptic transmission and the functional manifestations of the individual neurones are preserved in the tested preparation.

Animals↗
PubMed1987

Cost-benefit analysis of hepatitis-B vaccination.

Since 1983 the Belgian insurance Fund for Occupational Disease (FOD) has refunded the cost of hepatitis-B (HB) vaccination. Vaccination has been carried out by occupational physicians selectively on staff in hospitals and medical-care institutions. At the end of 1986, 40,000 people at high risk of HBV infection had been vaccinated. The vaccination costs are largely offset by the benefits resulting from the striking fall in the number of HB cases. The financial investment has proved economically beneficial for the insurance fund.

Belgium↗
PubMed1986

Comparison of the effect of gamma-aminobutyric acid and its derivative baclofen on the activity of Purkinje cells of frog cerebellum in vitro.

The inhibitory effect of gamma-aminobutyric acid (GABA) and its synthetic derivative baclofen were compared in frog cerebellum in vitro. Baclofen inhibited synaptic transmission from parallel fibres to the Purkinje cells in EC50 concentrations approximately 200-fold lower than for GABA. In addition to its inhibitory effect, GABA induced temporary facilitation of responses in the dendrite zone by a mechanism dependent on the presence of a normal Cl- concentration; the inhibitory phase was only partly sensitive to reduction of the Cl- concentration in the medium and to the administration of picrotoxin. The action of baclofen, which was unaffected by these treatments, requires an intact catecholamine and serotonin pool, since it is ineffective in reserpine-treated animals. Both substances also influence the excitability of parallel fibres. In solutions with a high Mg2+ and a low Ca2+ concentrations GABA inhibits the spontaneous activity of Purkinje cells by acting on the postsynaptic membrane of the soma and the primary dendrites. The effect of baclofen is evidently the outcome of inhibition of transmitter release from presynaptic endings.

Action Potentials↗
PubMed1979

Synaptic responses of reticulospinal neurons in the cat: spinal cord dorsal funiculi are an effective source.

Stimulation of spinal cord dorsal funiculi (DF), as compared with stimulation of ventrolateral fascicle (VLF) in which the spinoreticular pathways are located, activated a higher percentage of reticulospinal (RS) neurons (95% vs. 75%). Polysynaptic EPSPs evoked from DF at C2 segment had shorter latency (10.1 msec +/- vs. VLF C2-13.2 msec +/- 0.9-mean +/- S.E.M.). When the intensity of stimulation was close to threshold (1.5 T), EPSPs from DF had steeper slopes on the increasing phase and were of longer duration. Threshold for setting up of synaptic activity from DF at the majority of observed RS neurons was low; recording of antidromic responses in hindlimb nerves showed that fast-conducting myelinized afferents were activated. The functional connection between DF and RS systems may participate in prompt and generalized reflex reactions.

Animals↗
PubMed1979

Caloric nystagmus: ENG in comparison with observation by Frenzel's glasses.

After caloric stimulation with water at 30 degrees C for 30 sec an electronystagmogram (ENG) was registered. Simultaneously with the ENG the test person's nystagmus was observed by Frenzel's glasses. If the evaluation is limited to the frequency of the nystagmus and if it is possible to neglect the velocity of the slow phase, the simple observation through Frenzel's glasses and its plotting on a time chart recorder is no less effective than an ENG for measuring the difference between the right and left labyrinth.

Adult↗
PubMed1979

Reticulospinal neurones with axons in the dorsal part of the lateral funiculus of the lumbar segments.

The presence of reticulospinal axons in the dorsal part of the lateral funiculus (DLF) of the lumbar spinal cord segments was tested in chloralose-anaesthetized cats. In the medial part of the reticular formation, 59 units which gave antidromic responses to stimulation of the isolated DLF of segment L1--L3 were observed. The rate of their axonal conduction was 20--120 m/s. 62% of the units generated discharge activity in response to electrical stimulation of the skin of the trunk and/or the limbs. The activating intraspinal pathways were localized in the DLF and the ventral part of the cord. The most effective natural stimulus was tapping. Monosynaptic control from cerebellar pathways was confirmed in 37% of reticulospinal neurones with axones in the DLF. The results showed that reticulospinal axones form part of the dorsal reticulospinal system in the lumbar cord region.

Action Potentials↗
PubMed1979

[Hearing results following tympanoplasty (author's transl)].

Tympanoplasty can produce a stable hearing improvement in many patients with chronically inflamed ears. In our series of patients, severe damage to the inner ear following surgery occurred in 3% patients and was associated with a hearing loss of greater than 15 dB. Complete hearing loss occurred in 0.2% of the patients reviewed. In patients with an intact ossicular chain, simple myringoplasty is associated with the best results. Loss of the stapedial arches affects the postoperative air-bone gap most significantly, while loss of the manubrium mallei or the creation of a radical mastoid cavity are additional negative factors. Extent or localization of ossicular fixation has no direct influence on hearing results when appropriate ossicular reconstruction is performed.

Cochlear Implants↗
PubMed1979

[Preserved human cartilage grafts and autogenous viable transplants for nose and middle ear (author's transl)].

57% of the preserved human cartilage chips being implanted in the nose lead to a remarkable up to a complete resorption. 94% of the patients have nevertheless a sufficiently or well working function of the nose; besides that they are as well satisfied with the shape of their nose. The most important reason for the resorption are mechanical factors; this has been shown by comparing the load of implanted tissue on the columella and on the dorsum of the nose. We can't exclude the possibility of late immunologic reaction. Comparing these results with those of the middle ear by missing any mechanical load, we registered nevertheless a remarkable loss of the volume of the cartilage. This is an intense indication for an immunologic reaction, especially because there is a more intense vascularisation in the middle ear and a strong activity of fibroblasts based on the mesenchymal potency of middle ear mucosa. It's only in the middle ear that preserved cartilage can be substituted by connective tissue, viable cartilage or viable bone.

Cartilage↗
PubMed1979

[A caloric vestibular test with increased positive evidence (author's transl)].

A decrease of the variance of a caloric test would increase the importance of the statement of this test. An important source of variance are the differences concerning the timecourse of the induced heat wave, determined by the different anatomic conditions in the petrous bone, particularly the pneumatisation. A constant temperature gradient is obtained by the irigation in a pessimum position with the head flexed 30 degrees to the front. This temperature gradient evokes immediately a constant maximum vestibular stimulus after having reflected the head 90 degrees to the back. Comparing this new method with the traditional irrigation, one can state an important reduction of variance. The dependence of the nystagumus response on caloric irrigation of the petrous bone demands a X-ray-examination according to the technique of Schüller before starting with the caloric examination. In case of differences between the right and left sides the described test would be necessary in our opinion.

Caloric Tests↗
PubMed1979

[Comparison of the results of incus interposition and artificial columella in tympanoplasty (author's transl)].

The average postoperative air-bone gap after interposition of an incus between tympanic membrane and stapes footplate is too high in case of missing crura of the stapes, it is 27 dB. The interposition of an artificial prosthesis, according to Shea and beeing made of "Platipore", leads to a statistically based lower air-bone gap with a mean of 20 dB. Concerning the change of bone conduction, there is no difference between these two methods of operation. The rate of artificial prosthesis which are perforating the tympanic membrane, increases after seven months up to 15%, but only 4% of the incuses invade the plane of the tympanic membrane after 22 months.

Bone Conduction↗
PubMed1978

Site on inhibition of the spino-bulbo-spinal reflex on stimulation of the anterior lobe of the cerebellum.

The effect of stimulation of the anterior lobe (AL) of the cerebellum on spinobulbo-spinal (SBS) reflex activity evoked by somatic and splanchnic afferentation was studied in chloralose-anaesthetized cats. Unit activity synchronous with the SBS component of the efferent discharge was observed at the level of motoneurons, descending axons of the dorsolateral and ventral funiculi and neurones of the reticular formation (RF). Conditioning stimulation of the AL inhibited this unit activity. Reticular formation units influenced from the AL had direct contact with segmental structures; these results showed that disappearance of the SBS reflex during AL conditioning is associated with the depressant effect of the cerebellar cortex on the reticular formation.

Animals↗