Svante Ödman

Movement-induced potentials in surface electrodes

Movement-induced potentials of streaming potential type were studied in various electrode configurations. The geometric design of the electrode was important for the reduction of noise generated by the movements of gel. Potential and impedance variations were measured for electrode movements in electrolytes. The impedance variations were small and the streaming potentials were electrolyte-concentration dependent and in the order of 10μV. The same type of study was carried out for electrodes applied to the skin. The conclusion from this experiment is that skin deformation potentials dominate the disturbance pattern in this type of recordings.

Mechanical pulse wave propagation in gel, normal and oedematous tissues

The velocity, attenuation and frequency content of the mechanical pulse wave propagation in gels of various water contents, in normal tissues from various sites and in oedematous tissues from different patients were investigated. The properties of the propagated pulse wave depend on the water content of the gel and the viscoelastic properties of the tissues. From the dependence of the pulse wave propagation velocity on elasticity, viscosity and density, information may be obtained concerning the effects of oedema on the mechanical properties of tissue.

Fish scales as biosensors

Abstract It is demonstrated how certain fish scales (in our case from Cuckoo Wrasse, Labrus ossifagus) can be used for biosensing purposes. These scales contain cells with pigment granules which are either dispersed or aggregated. The pigments of an isolated fish scale are, e.g., aggregated by noradrenaline or other catecholamines. The aggregation can be measured by a simple photometer or by fibre optical probes. The sensitivity is very large. Nanomoles of noradrenaline can be easily measured. We discuss therefore the possibility of developing sensor probes for clinical use based on the fish scales.

Effects of sodium nitrite on ultraviolet light-induced relaxation and ultraviolet light-dependent activation of guanylate cyclase in bovine mesenteric arteries

It was demonstrated that precontracted strips from different bovine mesenteric arteries showed variation in sensitivity to ultraviolet radiation (366 nm). Some strips relaxed when they were exposed to ultraviolet light, others showed no sensitivity at all and, finally, some showed contraction. However, all arteries relaxed when they were irradiated with UV-light in the presence of 10 microM NaNO2. Ultraviolet radiation (366 nm) increased the activity of guanylate cyclase in crude homogenate from bovine mesenteric arteries by about 20-fold in the presence of NaNO2, while UV-light in the absence of sodium nitrite had no effect on the guanylate cyclase activation. These results support the notion that nitrite may be essential for vascular smooth muscle relaxation by UV-light, possibly through the release of nitric oxide.

Optical biosensors based on fish pigment cells

Abstract Melanophores (black pigment cells) in isolated fish scales have the ability to either aggregate their intracellular pigment granules to the centre or disperse them throughout the cell. Noradrenaline stimulates aggregation within these cells. The sensitivity of noradrenaline is considerably increased after approximately one week of isolation of the scales in a tissue culture medium. In order to measure simultaneously pigment aggregation in several isolated scales, a multichannel fibre-optic system has been developed. The system enables the scales to be constantly perfused with tissue culture medium, which in turn allows measurements to be made over long periods of time. After nine days of isolation there is an approximately 12 000-fold increase in noradrenaline sensitivity. The fibre-optic system, combined with cultured melanophores and molecular biology techniques, should provide a number of interesting biosensing possibilities.

Fish-scale photometry and in vitro cytotoxicity

Abstract Certain fish scales contain thousands of black pigment cells (melanophores). Electrical stimulation of such a scale causes intrinsic nerves to release noradrenaline, which in turn aggregates the pigment within each melanophore. The aggregation is readily quantified by the aid of a simple fish-scale photometer. The probability of detecting toxic effects of chemicals (and their mode of action) is supposed to be quite good in such a system. The present contribution describes fish-scale photometry for in vitro estimation of acute toxicity of the first ten MEIC (Multicentre Evaluation of in vitro Cytotoxity) chemicals. The IC50 (50% inhibition of nerve-induced pigment aggregation) values of the tested chemicals (except one) are close to or far below the known lethal blood concentrations in man. By comparing these IC50 values with those of exogenously added noradrenaline, it is concluded that most of the tested chemicals mainly inhibit the nerve function. The present results suggest that fish-scale photometry may be of potential value as an inexpensive toxicity screening method.