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J Dymecki

Publications and source records attributed to J Dymecki.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

[Dynamics of synaptic changes in experimental audiogenic epilepsy].

The dynamics of ultrastructural changes in axonal endings were studied after experimental epileptic seizures. Mice and rats from strains with genetically--determined audiogenic epilepsy were used as a model of epilepsy. The animals were divided into 3 groups: in group 1 only one seizure was evoked, in group 2 eight seizures within 4 hours, group 3 served as control. The animals were killed immediately after the last seizure, 30 min. after it or 1 hour after the seizure. Hippocampal gyrus cortex was impregnated with zinc-iodide-osmium tetroxide and synapses were examined under electron microscope. The number of synaptic vesicles showing positive reaction with zinc iodide was calculated in 20 synaptic boutons in each group. A significant correlation was demonstrated between the frequency of seizures and the survival time after the seizure on the one hand, and synaptic changes, on the other. In the control group 97% of synaptic vesicles were filled with neurotransmitter substance giving positive reaction with zinc iodide. Immediately after the single seizure 46% of synaptic vesicles were found emptied, 30 min. later the neurotransmitter substance was demonstrated in 79% of vesicles, 1 hour later 82% of vesicles had normal appearance. Immediately after serial seizures 91% of vesicles were found empty, 30 min. later the neurotransmitter was present in 50% of vesicles, 1 hour later in 78%. In another group of animals seizures were evoked once daily for 40 days (chronic epilepsy model). Synaptic changes were different: the synaptic boutons were swollen, the number of vesicles was reduced, greatly enlarged vesicles and clear membrane-bound vacuoles appeared. They evidenced degenerative character of changes. It is suggested that degenerative synaptic changes may be a substrate of epileptic dementia.

Animals↗
PubMedDate not supplied

Brain serotonin and epileptic seizures in mice: a pharmacological and biochemical study.

5-Hydroxytryptophan (5-HTP) reduced the intensity of both audiogenic and pentylenetrazol seizures. p-Chlorophenylalanine reduced audiogenic seizure (AGS) susceptibility but failed to change the pentylenetetrazol seizure (PTS). Drugs blocking brain serotonin (5-HT) receptors suppressed AGS but caused no clear effects upon PTS. Pentylenetetraziol-induced shock increased brain 5-hydroxyindoleacetic acid (5hiaa) concentrations and decreased 5-HT levels. Single audiogenic shock decreased the acumulation of 5-HT and 5-HIAA in the brains of mice pretreated with 5-HTP. On the other hand PTS increased the accumulation of 5-HT and 5-HIAA in the brains of mice pretreated with 5-HTP. It is suggested that AGS decrease brain 5-HT turnover whilst PTS cause an opposite effect.

5-Hydroxytryptophan↗
PubMedDate not supplied

[Usefulness of a strain of mice with genetically determined audiogenic epilepsy as a model of experimental epilepsy].

Behavioural and bioelectric characteristics of epileptic seizures caused by acoustic stimulus in mice from the Swiss Albino Rb strain with genetically determined audiogenic epilepsy are presented. The value of this epilepsy model is emphasized stressing that the epileptogenic stimulus acts from a distance, causing no damage to the nervous system and no artifacts. Besides that, seizures can be provoked at a definite frequency and at arbitrarily chosen time. A disadvantage of the model is the necessity of provoking each seizure separately which causes that this model cannot meet one of the conditions of Jasper's definition concerning spontaneity of seizure development. With regard to the course of seizure it is emphasized that it is somewhat similar to human grand mal epilepsy representing the basic phases of seizure. Electrophysiological investigations carried out under conditions of long-term fully reproducible experiment demonstrated presence of very evident and rich electrocorticographic symptomatology of audiogenic epileptic seizure whose behavioural phases show a high correlation with phasic changes in bioelectric brain activity. The investigations carried out in sleep failed to demonstrate differences in the susceptibility to seizure development when the stimulus was applied in waking state or in any of both phases of sleep. This strain is useful to morphological ultrastructural, biochemical and possibly electrophysiological investigations.

Animals↗
PubMedDate not supplied

The degree of genetic disparity between donor and host correlates with survival of intraventricular substantia nigra grafts.

We have evaluated the degree of genetic disparity that permits survival of intraventricular brain tissue grafts without additional immunosuppression. Fisher 344 rats (n = 100) with unilateral substantia nigra lesions were used as hosts. Donors consisted of Fischer 344 rats (isografts), Sprague-Dawley rats (allografts), mice, hamsters, and rabbits (xenografts). Grafts were obtained from the ventral mesencephalon of embryonic animals. The functional properties of the grafts were measured by behavioral rotation tests. Frequency of graft survival determined histologically was related to the degree of genetic disparity between donor and host. In comparing rabbit and hamster xenografts, the greater degree of disparity for the rabbit-to-rat grafts was associated with a shorter period of behavioral recovery (3 weeks vs. 5 to 6 weeks) after transplantation. It is concluded that rejection of intracerebral brain tissue grafts does not occur as an all-or-none process, but instead varies as a function of the degree of genetic disparity between donor and host.

Animals↗
PubMedDate not supplied

[The ascending frontal artery system: morphological and radiological analysis].

After an analysis of anatomical preparations of cerebral hemispheres, postmortem angiograms and normal intravital angiograms the morphological pattern of the branches of the middle cerebral artery forming the system of the ascending frontal artery and the most frequent varieties of the origin, course and shape of these branches were evaluated.

Cerebral Angiography↗