Biomedical subjects
Publications and source records attributed to S Trojan.
Live neuronal suspensions, prepared from the hippocampal region of donors aged 20 embryonal days, were observed in the Nomarski Differential Interference Contrast. Many neurones displayed profiles, resembling dendrites or axons and both principal hippocampal neurones (pyramidal and granular cells) were identified. For transplantation studies, donors of a younger embryonal age are thus recommended.
Motor seizures elicited by isonicotinehydrazide (INH) were studied in 188 male albino rats aged from 5 days to adulthood. INH was found to be able to induce both minimal, predominantly clonic, and major, i.e. generalized, tonic-clonic seizures during the whole course of development. Tonic hindlimb extension was observed as a part of major seizures even in the youngest group studied. Fifty-percent convulsant doses counted in 7-, 12-, 18-, 25- and 90-day-old rats did not significantly differ. The developmental changes found were a poor time resolution of minimal and major seizures during the first two postnatal weeks and significantly longer latency of major seizures in 5- and 7-day-old rat pups in comparison with all other age groups. The importance of the developmental stage of a generator of seizures as well as of the maturation of triggering mechanisms was demonstrated comparing the present results with our previous data.
The administration of allopurinol significantly increased resistance to repeated hypobaric hypoxia, while hypoxanthine decreased it. The administration of adenine or inosine (25 mg/kg) was without effect. The results show pathogenic significance of xanthine oxidase-dependent production of free oxygen radicals in posthypoxic damage. In other experiments, the administration of 50% ethanol (12 ml/kg) by gastric catheter increased plasma xanthine oxidase activity in both rats and hamsters.
The sensorimotor area of the cerebral cortex of the laboratory rat was repeatedly stimulated by electric current after 10-minute intervals which led to the development a gradual prolongation of self-sustained after-discharges (SSAD). One and 10 minutes after termination of the third SSAD the authors analyzed under the electron microscope synapses type I after to Gray from the second cortical homotopic area of the unstimulated hemisphere. They evaluated the curvature of the active zone of synapses. Evidence was provided that one minute after termination of the fit the number of negatively curved synapses increased and the number of synapses with a straight active zone decreased. The number of synapses with a positively curved active zone does not change. Ten minutes after termination of SSAD in the experimental animals the number of positively curved elements declines and the number of negatively curved synapses increases. There is no significant difference in the number of synapses with a straight active zone. The authors discuss possible functional consequences of the mentioned changes.
In male laboratory rats, Wistar strain, 2 and a half years old, quantitative morphometric analysis of synapses (type I after to Gray) from the second layer of the sensorimotor area of the neocortical region was performed. Evidence was provided of enlargement of the area of presynaptic formations, their circumference and of prolongation of the active zone of the synapse. The absolute number of agranular synaptic vesicles does not change, however, the number of vesicles per area unit declines (1 micron 2). This change was proved in all regions of the presynaptic ending. The enlargement of the area of synaptic endings is discussed in relation to possible shifts of water and electrolytes between the extracellular and intracellular space as a result of ageing of nervous tissue. The authors discuss also the passive change caused by a decrease of neuropil structures and narrowing of the extracellular space. The relative decline of the number of synaptic vesicles in the entire synapse and thus in the vicinity of the active zone is taken to be the morphological basis of a certain restriction of synaptic transmission in the sensorimotor area of the cortex in old age.
The duration of postoperative analgesia following femoral nerve block with a catheter technique was studied. Intermittent doses of bupivacaine were given to 208 consecutive patients presenting for open repair of the anterior cruciate ligament, initially 0.5% and thereafter 0.25% 0.4 ml/kg 2-4 times daily. Supplementary analgesia with piritramide 0.15 mg/kg I.M. was provided 4-6 hourly as required and the number of analgesic demands recorded. Based on the duration of analgesia and on the number of analgesic demands required, good or satisfactory analgesia was obtained in 88% of the patients. The catheter remained an average of 2.8 days in position and no infectious or irreversible neurological complications were seen. It is concluded that femoral nerve block using a catheter technique, provides safe and reliable analgesia, improves patient mobility, has a high patient acceptance and is capable of reducing systemic analgesic demand following anterior cruciate ligament repair.
The authors draw attention to the danger of the development of hyperaemia because of the possible influence of free oxygen radicals during the hypoxic period on brain cells. Using radioactive microparticles of 85Sr the authors assessed the cardiac minute volume and blood flow through the medulla oblongata, cerebellum, subcortical area and cerebral cortex in adult laboratory rats 20 hours after 2-minute ischaemia induced by positive radial acceleration of 10 G. The results indicate an increase of the local blood supply in the investigated parts of the brain, although lower than after 8-hour exposure to high altitude hypoxia at 7000 m.
Kainic acid (KA) was injected into both lateral ventricles of the brain of adult laboratory rats with the aim of verifying whether damage to afferent fibres in the hippocampal CA1 area would also be reflected in changes in the dendritic arborization of the neurones after maturation of these structures was completed. A significant proportion of the afferent fibres ending in area CA1 comes from CA3-4. The neurodegenerative effect of KA on the neurones in CA3-4 thus leads to marked reconstruction of the dendritic network of the pyramidal cells in the CA1 area. In the CA1 area of the experimental animals, there are fewer segments in the proximal part of the basal dendrites and in the lateral branches of the apical dendrites. The total number of segments in the apical dendrites is smaller and the higher order segments are likewise reduced. In the experimental group, the segments of both the basal and the apical dendrites are shorter. In the experimental animals, dendritic spine density in the lateral preterminal branches, the distal part of the apical shaft, the terminal segments of the lateral branches and the apical preterminal branches are smaller than in the controls, whereas in the segments proximal to the soma of the pyramidal cells it is greater. It can be seen from the results that area CA1 of the hippocampus is endowed, even in adulthood, not only with high functional plasticity, but also with surprisingly high morphological plasticity.
The author demonstrated the protective effect of intraperitoneally administered vitamin E on the resistance of the laboratory rat to stagnant hypoxia induced by 5xg positive radial acceleration. A dose of 300 mg/kg body weight proved to be the most effective.
Implantation of an embryonal hippocampal tissue suspension into the area of the kainic acid lesion brought about an increase of the number of neurons. These neurons formed dendritic trees of an irregular pattern. Only neurons located within the pyramidal layer had the typical arrangement of pyramidal cells, but their dendrites were shorter and less branched.
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An outline of Prof. Laufberger's concept of practical exercises in physiology, proposed just after the Second World War, is given. Especially, his new pedagogical approach is emphasized, here. Further, the development of the organization of practical courses in the Institute of Physiology in Prague is described: e.g. the modernization of the methods used, and of the educational process in early 70 s'. Today, the importance of biocybernetics is growing.
Pyramidal neurons of the CA3 hippocampal area were eliminated by means of the kainic acid. Subsequent transplantation of the embryonal hippocampal tissue suspension brought about an increase of the number of neurons. Groups of nerve cells were located at the tips of the implantation tracts. Neurons formed dendritic trees of various complexity. Most of them had an irregular dendritic branching pattern. Only those located within the pyramidal layer, had the typical arrangement of several basal and one apical dendrite.
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