In recent years, with the installation of power lines and the use of electrical appliances such as mobile phones, computer monitors and the like, the presence of strong electromagnetic fields has become a familiar phenomenon. Moreover, with the progress in pharmacology, nutritional science and organic chemistry, new medicines and food additives as well as chemical substances hitherto unknown to nature are constantly under development. To elucidate the influence that these artificial physical and chemical environmental factors have on biological matter, investigations with statistical techniques focusing on humans and experiments with animals have been performed.
However, in investigations with statistical techniques focusing on humans, it is extremely difficult to provide constant conditions for a population, and a rather long investigation time is necessary. Furthermore, in humans there are subtle differences with respect to their individual genetic background, their way of life, their past eating habits and so on. For example, let us suppose, that we select high voltage power lines as a source of electromagnetic waves near our bodies to examine the capacity of electromagnetic waves to cause cancer in a human body. In that case, it is very difficult to account for different examination conditions among those living near the high voltage power line concerning their genetic history, nutritional history, classification of cancer ridden organs, age, body weight, sex, personal preferences, medical history and virus infections. When the statistical examinations are performed, it is necessary to perform enough model experiments using laboratory animals for which the above conditions can be adjusted easily. Then, it is important to perform experiments at the tissue level, especially with networks of cells, which is not possible with the experiments described above. In the field of pharmacology, for example on the way towards the development of a new medicine for the central nervous system, rather than using the brain of a laboratory animal, an isolate nervous cell is prepared, dispersed and cultivated, and the effect of the new medicine is examined on the individual cell level under pharmacological, electrophysiological, morphological and immunological aspects. However, the cerebral nervous functions are controlled by a nervous circuitry of systematically accumulated nervous cells. Therefore, if the brain's high order functions are taken to be governed by the general behavior of the nervous circuitry, then there can be no doubt that it is very important to elucidate the influence of those medicines on the nervous circuitry, as has already been stated above. Nevertheless, the reason why the influence of medicines on the nervous circuitry and on the intracellular network at the organic level has not been examined in the past is that first of all, there was no technique of screening the nervous circuitry with brain slices. Therefore, in the present situation, various kinds of medicines are tested with the usual pharmacological experiments and come to practical use, while their operational mechanism in the nervous circuitry is still unclear. For example, the famous insomnia medicine Halcion is thought to suppress excessive nervous activity of the limbic and the cerebral cortex due to a functional exasperation of GABA receptors accompanying the excessive polarization of nervous cells. However, this effect became clear by using individual nervous cells, yet it is by no means clear, what influence is exerted on the entire nervous circuitry. The schizophrenia medicines haloperidol and chlozapine are likewise administered without examining their influence on the nervous circuitry. On the other hand, medicines that show an enormous effect on the nervous circuitry and have few side effects may often not be deemed to be effective when subjected to conventional screening methods, and there is a possibility that they do not come to practical use.
The necessity of research on the biological organ level is being recognized not only for the functional explanation of the nervous circuitry but also for research on other biological organs, and in biological fields such as medicine and pharmacology there is an earnest desire for the development of a device which realizes this research efficiently and with high reliability.
Thus, the development of a device that can be used to observe with time the physical and chemical properties of tissue or cells extracted from biological matter, and maintain the physical and chemical environment near the tissue or cells constant, yet enables controlled change of the physical and chemical environment near the tissue or cells for experimental purposes, and the simultaneous investigation of a large amount of samples is strongly desired.
The purpose of the present invention is to provide a method of testing medicines and a device for the same, and a method of measuring the physical and chemical properties of tissue or cells and a device for the same, and thus to match the above desires.