[Spectral analysis of self-oscillating motility in isolated plasmodial strand of Physarum polycephalum].

In this study the experimental dependencies of the velocity of shuttle endoplasmic motion in the isolated plasmodial strand of Physarum polycephalum obtained by laser Doppler microscopy are presented. The spectral analysis of the time dependencies of the endoplasm allows obtaining two distinct harmonic components. Influence of KCN and SHAM--inhibitors of cellular respiration--leads to a complete cessation of endoplasmic motion in the strand. After removal of the inhibitors the respiratory system becomes normal, gradually restoring the activity of both harmonic oscillation sources. Based on the spectral analysis the simulated time-dependent velocity of the endoplasmic motion is rather good consistent with experimental data.

A new method of bone tissue measurement based upon light scattering.

In recent years, time-resolved spectroscopy systems using near infrared pulsed laser have been applied to develop optical computed tomography. We applied this technique to measure the optical properties of osseous tissues. First, we gradually demineralized 10 mm blocks of bovine trabecular bone with EDTA, maintaining the absorption characteristics and structure but varying the hydroxyapatite content, thus creating specimens differing only in light scattering properties. We used computer densitograms to assess light penetration, and analyzed the correlation with bone mineral density (BMD) as with dual-energy X-ray absorptiometry scans. The light penetration increased with decreasing BMD. Second, using the above-mentioned pulsed laser time-resolved spectroscopy system, we investigated the correlation between the BMD and the time response waveforms of 10-mm blocks of bovine cortical bone, trabecular bone, and surrounding tissue as well as human trabecular bone. The human lumbar vertebral bone also displayed an inverse correlation between BMD and maximum light penetration and a positive correlation between BMD and peak time delay. This is the first demonstration of a correlation between BMD and light scattering properties showing that BMD can indeed be measured with light. Our results show the possibility of obtaining information on internal bone structure and composition in vivo through assessment of the waveforms obtained by a time-resolution system in the near infrared region.

Application of the zooming method in near-infrared imaging.

Images of a tissue simulating phantom are obtained by inverting a limited number of continuous-wave relative transmission measurements. The diffusion approximation to the radiative transfer equation is used as a light propagation model. The inversion procedure is based on a quasi-Newton method and the Levenberg-Marquardt method, and the imaging parameter is the absorption coefficient of the phantom. It is shown that the resolution of the images can be improved using the zooming method. The image indicates the presence of an inhomogeneity in approximately the correct location, but the shape and size of the inhomogeneity in the reconstructed image differs from the shape and size of the actual inhomogeneity. Possible methods for further enhancement of the images are discussed.

[A drop in "apparent" blood viscosity due to administration of high-molecular polymer capable of augmenting viscosity].

Influence of a high-molecular compound capable of augmenting viscosity, namely: polyethylene oxide Polyox WSR-301, on hemodynamic parameters in rat mesenteric microvessels was investigated. A substantial decrease in the arteriolar hemodynamic resistance caused by the polymer was revealed. Special research has shown that this reaction is not connected with a vasodilatation and, therefore, is caused by a reduction in the "apparent" viscosity of the blood, i.e., it is a consequence of changed properties of the blood flow.

[A decrease in the hydrodynamic resistance in the mesenteric arterioles of rats injected with the polyethylene oxide Polyox WSR-301]. / Umen'shenie gidrodinamicheskogo soprotivleniia v arteriolakh bryzheiki krys pri in''ektsii poliétilenoksida Polyox WSR-301.

The infusion of polyethylene oxide in anesthetised rats in a total dose of 10(-7) g/ml caused a 10-16% reduction in blood pressure. This injection has been associated with 17% decreased pressure (servo-nulling method) and 54% increased blood velocity (laser Doppler fluxmetry) in mesenteric arterioles (d - about 24 mu), but no increase in their internal diameter was observed (image-split method). Vasodilatation (adenosine, 10(-5) M) did not change the hemodynamic response of the arterioles to polymer infusion. These results suggest that microdisturbances of blood flow which can be diminished by drug-reducing polymers are more important for the vascular resistance to blood than it has been previously.