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Biomedical subjects

H Nowak

Publications and source records attributed to H Nowak.

120 records · Page 7Linked to original sources
PubMedDate not supplied

Habituation of the auditory evoked field component N100m in male patients with schizophrenia.

The auditory evoked field (AEF) component N100m represents the most prominent and stable peak of the AEF, and its alterations in patients with schizophrenia are an extensive topic of neuropsychiatric research. In our current study, the degree of N100m habituation was investigated in 20 male schizophrenics and 19 healthy male controls. Participants were stimulated monaurally with 270 trials of 1000 Hz tones separated by an interstimulus interval between 800-1800 ms. The trial sample of the bilaterally recorded AEF was separated into three consecutive blocks of 90 trials and these blocks were compared with each other. The mean global field power (MGFP) of the N100m decreased on average 9.1% from the first to the third trial block, while the N100m latency was increasing. The analyses of the influence of habituation revealed a systematic change of dipole location in inferior-superior direction, mainly in the left hemisphere. This habituation effect was found to be the same for both groups. The groups also did not differ in the N100m latency increase and MGFP decrease, except for one parameter. The right-hemispheric MGFP decrease from the first to second block was found to be more pronounced in patients compared to controls. However, this difference was related to medication with clozapine. Overall, the habituation behaviour of the N100m seems to be undisturbed in schizophrenic patients.

Adult↗
PubMedDate not supplied

The influence of local tissue conductivity changes on the magnetoencephalogram and the electroencephalogram.

We examined the influence of local tissue conductivity changes in the vicinity of a dipolar source on the neuromagnetic field and the electric scalp potential using a high resolution finite element method model of the human head. We found that the topology of both the electric scalp potential and the neuromagnetic field (and consequently dipole localization) is influenced significantly by conductivity changes only in voxels adjacent to the source. Conductivity changes in these voxels yield a greater change in the amplitude of the magnetic field (and consequently in the dipole strength) than in the amplitude of the electric potential.

Action Potentials↗
PubMedDate not supplied

Sensitive magnetic sensors without cooling in biomedical engineering.

Magnetic field sensors are used in various fields of technology. In the past few years a large variety of magnetic field sensors has been established and the performance of these sensors has been improved enormously. In this review article all recent developments in the area of sensitive magnetic field sensory analysis (resolution better than 1 nT) are presented and examined regarding their parameters. This is mainly done under the aspect of application fields in biomedical engineering. A comparison of all commercial and available sensitive magnetic field sensors shows current and prospective ranges of application.

Biomedical Engineering↗
PubMedDate not supplied

[Acoustically evoked brain magnetic activity in normal and growth retarded fetuses during the third trimester of pregnancy].

The fetal magnetoencephalogram with a 31 chanal biomagnetometer made by Philips was measured in a fetal 1F-phase in 20 normotroph unimpaired and in 14 growth retarded fetuses with a birth weight < 5 percentile after completed 36th gestational week. Trough defined acoustic stimulations, which were applied over the maternal abdominal wall, it was possible to measure acoustic evoked cerebromagnetic field changes using a special computer programs. The registrated evoked cerebromagnetic field changes had a latence time of 112.8 +/- 18.4 ms in normotroph fetuses and 130.9 +/- 18.5 ms in hypotroph fetuses. The difference was significant (p < 0.01). The presented results lead to the conclusions that the fetal magnetoencephalography makes a differentiation between normal and disturbed fetal cerebral integrity possible.

Embryonic and Fetal Development↗
PubMedDate not supplied

[Decrease of mitogen stimulation of lymphocytes in rheumatoid arthritis].

Peripheral blood lymphocytes of 51 patients with rheumatoid arthritis and of 14 healthy blood donors were cultivated in autologous and homologous normal pool-serum and stimulated with phytohemagglutinin (PHA-P), concanavalin A (Con A) and pokeweed mitogen (PMW) in different doses. In autologous as well as in homologous pool-serum the 3H-thymidine uptake of stimulated lymphocytes from patients with rheumatoid arthritis was significantly depressed independent of the mitogen concentration used. Serum from patients with rheumatoid arthritis depressed the activation of blood donor lymphocytes by Con A and PWM. The depression of lymphocyte activation was not related to the presence of rheumatoid factors in the serum, the severity of the disease and the anti-rheumatic therapy.

Arthritis, Rheumatoid↗