This work is a qualitative study of an organism''s physiological adaptative response to stress. The experimental data were selected from a previous study leading to the conclusion that stress may be considered as a topological retraction within a vital space that must be more precisely defined. The experimental methodology uses rat poisoning by neurotoxins. The control parameter is the intensity of the toxic doses. Measured parameters are the animals'' survival rate and the kinetics of cerebral acetylcholinesterase activity. The results, when (...) expressed as a function of the inverted doses, show a characteristic evolution. The pattern of the curve closely resembles a vortex profile. This analogy is studied more extensively in both the physical and biological domains. These findings help to clarify the concept of biological stress which presents the same vectorial properties as hydrodynamic vorticity. In particular, the dissipation of stress and the dissipation of vorticity seem to obey the same laws. This observation is valid for both diffusion and convection processes. The decompensation phase of stress could be compared with the instability and turbulence in flows.Our approach in this paper is mainly to establish a general and phenomenological description of the stress response fitting experimental observations. (shrink)

Soman, an anticholinesterasic neurotoxic drug, induces epileptic seizures during severe intoxication. Their trigger conditions still remain unknown and a great variability between animals is observed. The butterfly model in the catastrophe theory has been used to explain these triggering conditions.We have developed a technique allowing, in freely moving rats, the « in vivo » determination of three sets of neurophysiological data, followed before and during a soman intoxication. For the same rat, we associated cortical acetylcholinesterase (AChE) activity by microdialysis with (...) both the assay of extracellular acetylcholine (ACh) concentrations and electroencephalographic (EEG) recording and power spectrum analysis (gamma band). Data have been analysed to define the critical parameters which lead to the epileptic fit. (shrink)

In tracing the survival reaction of an organism, following a vital stress, we have proceeded from the breakdown of a cerebral enzyme as a function of the constraint, to its initial and spontaneous recovery. We have so observed a partial enzymatic recovery, the velocity of which being variable with respect to the constraint intensity. This velocity is expressed asdq/dt, that is, the quantity of enzymedq recovered per unit of timedt. In this paper, the basic idea is to consider the inverse (...) parameterdt/dq, that is, the timedt needed by the organism to recover a given quantity of enzymedq. The integration of this parameter over the constraint accumulated by the stressed organism allows us to determine a timeT which appears to be variable when observed by a distant observer.The properties of this timeT are discussed with the help of an analogical approach based on hydrodynamical and cosmological models. (shrink)