Biomedical subjects
B Hinz
Publications and source records attributed to B Hinz.
[New findings on endogenous regulation of glucocorticoids].
Explore the source record for details and available documents.
Failure of the steroid anaesthetic alphaxalone to inhibit CRF-induced ACTH secretion in rats in the fast feedback time domain.
Explore the source record for details and available documents.
Fast negative feedback actions of corticosterone and of dexamethasone on CRF-stimulated ACTH secretion in rats.
Explore the source record for details and available documents.
Psychophysical assessment of sinusoidal whole-body vibration in z-axis between 0.6 and 5 Hz combined with different noise levels.
Nine healthy sitting males evaluated the intensity of vertical whole-body vibration (WBV) in z-axis at four frequencies (F1 = 0.63 Hz, F2 = 1.25 Hz, F3 = 2.5 Hz, F4 = 5 Hz) and two intensities (I1 = 1 ms-2 rms, I2 = 2 ms-2 rms) by cross-modality matching (CMM). The subjects were simultaneously exposed to low-frequency noise at two levels (L1 = 65 dBA, L2 = 86 dBA). L1 and L2 were context conditions which did not have to be evaluated by CMM. The results indicate a flat response between F2 and F3; the sensitivity increases towards F1. Different exponents of Stevens' power law for the frequencies of WBV contradict the frequency range tested to be a sensory continuum. L2 caused practically significantly stronger sensations of the WBV-intensity from F1 to F3 (I1) and at F2 (I2). No synergistic effect of noise and WBV was shown at F3I2. Weighting factors were calculated for all exposure conditions using Stevens' power law. The weighting of F2 and F3 contradicts that of the International Standard ISO 2631-1985 (E). The results enable recommendations for the frequency weighting of WBV between 0.63 and 1 Hz, as well as for the equivalence of noise and WBV with combined exposure.
[Laboratory studies of vibration transmission in motor vehicle seats].
Operator seats (Models 050 and 500, Möve) were examined with vertical sinusoidal whole-body vibration (WBV) in the frequency range from 1 to 40 Hz (1.5 and 3.0 ms-2rms) and with simulated stochastic vibration of combines for the harvest of sugarcane. Six male subjects volunteered for the experiments. The WBV transmitted from the seat mounting base to the seat cushion and head were compared with data of a hard experimental seat. Interindividual differences cannot be explained by different body masses only. The iolation and main resonance of the two operator seats differed. Additional resonant peaks occurred above 6 Hz. They can cause unfavourable conditions at certain applications. The operator seats tested are probably suited for the reduction of WBV exposure on combines for the harvest of sugarcane.
[Laboratory studies on the subjective evaluation of motor vehicle seats].
Operator seats (Models 050 and 500, Möve) were examined with vertical sinusoidal whole-body vibration (WBV) in the frequency range from 1 to 40 Hz (1.5 and 3.0 ms-2 rms) and with simulated stochastic vibration of combines for the harvest of sugarcane. Six male subjects volunteered for the experiments. The subjective assessments of operator seats by cross-modality matching, paired comparisons, and questionnaires were compared with data of a hard experimental seat. Transmitted WBV and subjective evaluation correlated partially only. Suggestions are derived for the improvement of the seats tested.
Isolated and combined effects of prolonged exposures to noise and whole-body vibration on hearing, vision and strain.
This study was carried out in order: (1) to examine the effects of isolated and combined prolonged exposures to noise and whole-body vibration on hearing, vision and subjectively experienced strain, and (2) to check the combined effects with repeated exposures. Six male subjects were exposed twice to noise (N) at 92 dBA, whole-body vibration (V) in the Z-axis at 4 Hz and 1.0 ms-2 rms, and noise and vibration (NV) for 90 min with each condition. Temporary threshold shifts of hearing (TTS) and their integrals (ITTS) were measured at 4, 6, 10, and 12 kHz. Visual acuity was examined by means of a very sensitive test. Cross-modality matching (CMM) of the handgrip force was used to judge the subjectively experienced strain. NV induced a clear tendency of higher TTS and ITTS than N, with several significant differences most pronounced at 10 kHz. With repeated exposures, the effect of NV decreased, while the reactions to N and V remained unchanged. The individual reactions to NV differed. The influence of the duration of exposures on vision depended on the condition; N caused time-dependent changes, whereas V did not. CMM-data increased with the duration of the exposure during V and NV. N was generally judged to be more straining than V; NV caused higher strain than V during the first 30 min of exposure only. Correlations between different effects suggest certain links between them. Additionally, less motivation--daily obtained by a questionnaire--often correlated with higher ITTS during N and NV. The results also illustrate the combined effects on the individual susceptibility, repetition of exposure, the kind of response, and, possibly, the actual psychic state.
Examination of spinal column vibrations: a non-invasive approach.
Accelerations of vertebrae during whole-body vibration (WBV) are used in occupational biomechanics for the prediction of internal stress. To avoid invasive techniques, a method for the calculation of bone accelerations was developed using measurements on the skin. The soft tissue between spinous processes L3 and T5 and miniature accelerometers stuck to the skin over them was modelled by a simple Kelvin element, whose parameters i.e. angular natural frequency omega n and critical damping zeta, describe an approximate transfer function between the bone (input) and the skin surface (output). The parameters were determined from free damped oscillations of the accelerometer-skin complex in the Z-axis, and depended significantly on the factors "subject" and "point of measurement". In one subject, the time courses of bone accelerations during sinusoidal WBV (4.5 and 8 Hz; 1.5 m.s-2 RMS) were calculated using separate transfer functions for each of 11 different spinal levels. Since the output signals on the skin were non-sinusoidal, the skin accelerations had to be treated with an inverse transfer function in the frequency domain. A comparison of accelerations measured on the skin and predicted for the bone mainly indicates that absolute peak values of bone accelerations are smaller and occur earlier. Both kinds of acceleration hint at differences in WBV-induced internal stress within the spine.
The nonlinearity of the human body's dynamic response during sinusoidal whole body vibration.
Explore the source record for details and available documents.
Effects of sinusoidal whole-body vibration on the lumbar spine: the stress-strain relationship.
The aim of this experimental study was to estimate the strain in the lumbar spine due to whole-body vibration (WBV). Four male subjects were exposed to vertical sinusoidal WBV with frequencies ranging from 1 to 15 Hz at two intensities (I1 = 1.5 ms-2 rms; I2 = 3.0 ms-2 rms). The compressive forces acting on the disc L3-4 during the extreme values of acceleration were predicted on the basis of anthropometric data, EMG of back muscles and the acceleration of the upper trunk, using a simple biomechanical model. The estimated mechanical activity of back muscles was not able to protect the spine under many exposure conditions. The highest compressive forces were predicted for WBV with 7.5, 8 and 4.5 Hz. The results suggest the possibility of fatigue failures at the endplates of lumbar vertebrae after intense long-term exposure to WBV.
[Possibility for the evaluation of spinal stress caused by whole body vibration in experimental conditions].
Explore the source record for details and available documents.
[Tinea barbae caused Trichophyton verrucosum].
Report on a 48-year-old man, incidentally occupied as a farmer who was infected by one of his calves. Due to insufficient therapy he produced an expanded tinea barbae.
[Employment at display screens].
Explore the source record for details and available documents.
[Transmission of pea enation mosaic virus by different subspecies and strains of the foxglove aphid, Aulacorthum solani (Kaltenbach)].
Explore the source record for details and available documents.
[The effect of the aphid forage plant on the vector ability of aphids].
Explore the source record for details and available documents.
Patterns of spontaneous motility in videomicrographs of human epidermal keratinocytes (HEK).
The subject of our observations was the spontaneous behaviour of normal and transfected human epidermal keratinocytes. Cell movements were recorded on video micrographs and analyzed by a mathematical approach, using new methods of image processing and statistical correlation analysis. Protrusive activity of single lamellae was examined using one-dimensional analysis of phase-contrast image sequences along section lines transversal to the cell edge. This method revealed high periodicity and correlation in the motility patterns of lamellae and ruffles. Two-dimensional correlation analysis of automatically digitized cell outlines was applied to detect spatiotemporal patterns and coordination of lamellar extension and retraction. Most cells showed regularly alternating pulsations of lamellar protrusions. In some extreme cases, extension waves rotating around the cell periphery were observed. The results were compared with computer simulations of two simple models for lamellar dynamics and shape deformation, based on few assumptions about chemical kinetics of F-actin and cytomechanical properties of the actin network, neglecting regulatory effects of actin-associated proteins or extracellular stimulations. The simulation results reproduced the main dynamical features of the observed real cells, indicating the possibility that the basic universal mechanism for lateral coordination of lamellipodial protrusion is the interplay between hydrostatic pressure and viscocontractile tension in the cortical F-actin-plasma membrane complex.
Shear stress modulates the expression of thrombospondin-1 and CD36 in endothelial cells in vitro and during shear stress-induced angiogenesis in vivo.
Binding of thrombospondin-1 (TSP-1) to the CD36 receptor inhibits angiogenesis and induces apoptosis in endothelial cells (EC). Conversely, matrix-bound TSP-1 supports vessel formation. In this study we analyzed the shear stress-dependent expression of TSP-1 and CD36 in endothelial cells in vitro and in vivo to reveal its putative role in the blood flow-induced remodelling of vascular networks. Shear stress was applied to EC using a cone-and-plate apparatus and gene expression was analyzed by RT-PCR, Northern and Western blot. Angiogenesis in skeletal muscles of prazosin-fed (50 mg/l drinking water; 4 d) mice was assessed by measuring capillary-to-fiber (C/F) ratios. Protein expression in whole muscle homogenates (WMH) or BS-1 lectin-enriched EC fractions (ECF) was analyzed by Western blot. Shear stress downregulated TSP-1 and CD36 expression in vitro in a force- and time-dependent manner sustained for at least 72 h and reversible by restoration of no-flow conditions. In vivo, shear stress-driven increase of C/F in prazosin-fed mice was associated with reduced expression of TSP-1 and CD36 in ECF, while TSP-1 expression in WMH was increased. Down-regulation of endothelial TSP-1/CD36 by shear stress suggests a mechanism for inhibition of apoptosis in perfused vessels and pruning in the absence of flow. The increase of extra-endothelial (e.g. matrix-bound) TSP-1 could support a splitting type of vessel growth.