ABSTRACT
The authors analyze experimental data on in vitro effects induced by chemicals that were used throughout MEIC toxicologic studies in ovalbumin and acetylcholinesterase of human RBC. Influence on proteins is compared to acute toxicity caused by the chemicals in humans and various cell lines. The conclusion is that the method is prospective for screening of acute chemical toxicity signs in humans.
Subject(s)
Acetylcholinesterase/metabolism , Erythrocytes/drug effects , Ovalbumin/metabolism , Poisons/toxicity , Acetylcholinesterase/drug effects , Cells, Cultured , Cyanates/toxicity , Erythrocytes/metabolism , Humans , In Vitro Techniques , Insecticides/toxicity , Malathion/toxicity , Nicotine/toxicity , Ovalbumin/drug effectsABSTRACT
Midbrain tectal evoked responses to electric stimulation of the optic nerve were investigated in shark (Squalus acanthias). An early positive component was found as a part of negative phase of "classic" negative-positive evoked potential. Similar component was recorded from the ipsilateral tectal hemisphere as well. An increase of the positive component along with penetration of the electrode, its resistance to functional blockade by KCl application to the tectum surface and recording of a similar potential from the ventricular floor surface after extirpation of the tectum suggested the localization of the source of this component outside the tectum. Existence of a focus of maximal activity located in the rostral part of undertectal brain structures and disappearance of early positive component after functional blockade and extirpation of this brain area indicate the leading role of thalamic nuclei in generation of this component.
Subject(s)
Dogfish/physiology , Evoked Potentials, Visual , Optic Nerve/physiology , Sharks/physiology , Tectum Mesencephali/physiology , Animals , Brain Mapping , Visual Pathways/physiologyABSTRACT
Afferent visual projections to the pallium of the telencephalon have been investigated in immobilized conscious dogfish Squalus acanthias using electrophysiological recording the evoked potentials and neuronal reactions elicited by electric stimulation of the optic nerve. Analysis and comparison of the parameters of the components of the evoked potentials in the telencephalon and tectum opticum indicate the existence of two visual subsystems (the retino-thalamo-telencephalic and the retino-tecto-thalamo-telencephalic ones) in the dogfish.
Subject(s)
Dogfish/anatomy & histology , Sharks/anatomy & histology , Visual Pathways/anatomy & histology , Animals , Brain Mapping , Electric Stimulation , Optic Nerve/physiology , Reaction Time/physiology , Retina/anatomy & histology , Superior Colliculi/anatomy & histology , Telencephalon/anatomy & histology , Thalamus/anatomy & histology , Visual Pathways/physiologyABSTRACT
In unanesthetized immobilized spiny dogfish sharks, functional organization of the forebrain afferent projections was studied with the aid of evoked potentials (EPs) and neuronal responses to adequate stimulation of the eye with light and to electric stimulation of the optic nerve. The forebrain spontaneous unit activity (from 0.1 to 2.8 Hz) changed in response to the optic nerve electric stimulation with latency varying from 58 to 280 msec. Two foci of maximum unit activity were found at the depth of the visual area: at the levels from 850 to 1050 microns and from 1400 to 1600 microns from the forebrain surface. Histogram analysis of the data obtained showed that the main components of EPs reflected postsynaptic processes occurring in the dendrites of the forebrain visual area.
