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Biomedical subjects

J Dymecki

Publications and source records attributed to J Dymecki.

At least 37 records · Page 2Linked to original sources
PubMed1990

Development of vessels in the foetal cortical transplant depending on the place of grafting in the rat brain.

Formation of new blood vessels within the graft is crucial for the survival of brain grafts. Moreover, it must occur rapidly to prevent ischaemic changes in the grafted neurons. A study was made of the development of the vascular system in the foetal cortical grafts depending on the place of grafting in the rat brain. Pieces of neocortical tissue from an 18-day old rat foetus were transplanted into the lateral ventricle, the striatum or the corpus callosum of 2 months old Wistar rats. The vascular system of the graft was visualized from coronal sections of the brain by means of Pickworth's technique 3, 7, 14 and 28 days after transplantation. After 3 days the vessels in the graft were absent. After 7 days the vessel pattern was poor and very simple and after 14 days the vessels formed large number of branches in the graft. After 28 days the pattern of the vascular network in the graft was similar to that of the vessels of the host brain. The size and branching of the vessels showed considerable variations depending on the localization of the graft.

Animals↗
PubMed1990

Intrastriatal grafts of adrenal medulla in hemiparkinsonian rats--ultrastructural study.

The aim of the study was to investigate the ultrastructure of the right striatum after intrastriatal adrenal medulla grafts in Wistar rats with a 6-OHDA unilateral lesion of the compact part of the right substantia nigra (SN). 12 adult rats were investigated. Two rats were intact, 2 received a sham SN-lesion. Ungerstedt's rotational test confirmed a significant lateral SN-lesion in all the animals. Two weeks after the SN lesion small samples of the adrenal medulla of 2-month old Wistar rats were prepared (0.5 mm3) and implanted stereotaxically into the middle-paraventricular region of the right striatum. The animals were perfused with 2.5% glutaraldehyd according to the following patern: 2--after 1 week of survival, 2--after 3 weeks, 2--after 6 weeks, and 2--after 3 months. 10 samples of ca 1 mm3 were taken from 3 regions of the right striatum (1) the region of the graft, (2) the region in the neighbourhood of the graft, (3) tissue at a long distance from the transplant. Macroscopic observation showed granulomatous-like tissue at the place of the implantation of the graft after 1 week of survival. After 3 weeks and later only the evacuated cavity was observed instead of the graft. A routine electron microscopic procedure was used to expose the material in a JEM 100 B electron microscope. The study of the ultrastructure indicated many leucocytes and microglia cells in the region of the graft as well as features of destruction of the adrenal medulla cells in the rats perfused 1 and 3 weeks after transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗
PubMed1989

Postmortem detection of measles virus in non-neural tissues in subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis, a rare, progressive, fatal central nervous system disease of children, is caused by measles virus. Clinical signs occur months to several years after recovery from acute measles infection. It is not known where the virus persists while the disease is inapparent. Involvement of organs outside the central nervous system has rarely been documented. To search for possible peripheral reservoirs of measles virus we used in situ hybridization to probe for measles virus RNA and immunocytochemical studies to localize measles virus antigens ina variety of organs taken at autopsy from confirmed cases of subacute sclerosing panencephalitis. Seven of 9 cadavers were found to contain measles virus RNA or antigens, or both, in at least one location outside the central nervous system. These sites included lymphoid organs such as thymus, spleen, lymph nodes, and tonsil, suggesting a role for lymphocytes in disease pathogenesis. Virus was also detected in kidney, lung, and glandular tissues such as pancreas, adrenal, and pituitary. These reservoirs may provide the antigenic stimulus leading to the elevated response characteristic for subacute sclerosing panencephalitis.

Adolescent↗
PubMed1989

[Morphological evaluation of tissue and cellular components of the corpus striatum, globus pallidus and substantia nigra in 7-day-old rats].

The aim of the study was the morphometric evaluation of tissue and cell composition of brain structures which are involved into transplantation in experimental model of parkinsonism in the rat-substantia nigra as the implanted structure and caudate-putamen as the host structure into which the graft is placed. Three parts of caudate-putamen (anterior, medial and posterior), three parts of substantia nigra (compact, reticular and lateral) as well as pallidum were investigated in 7-day-old rat. It was found that the density of nerve cells is highest in medial part (2236/l mm2), lower in anterior part (2129/1 mm2) and the lowest in posterior one (1842/1 mm2). The number of giant neurons in relation to the rest of neurons in anterior, medial and posterior parts of caudate-putamen was 1:268, 1:147 and 1:545 respectively. This indicates that the numbers of complexes formed by giant neurons with other neurons vary depending on the area of this brain structure. The zonal differences in distribution and size of neurons in caudate-putamen should be taken in account in qualitative and quantitative studies.

Age Factors↗
PubMed1989

[Results of cross-species transplantation of substantia nigra to the lateral ventricle of the brain of rats with experimentally-induced Parkinson disease].

The method of compensation of dopamine (DA) deficit in the striatum by living, DA producing cells implanted into the brain, creates new hopes for patients with Parkinson's disease. In view of many ethical and legal problems, connected in some countries with obtaining human fetal tissue for transplantation, cross-species transplants would be an attractive alternative. The subject of our investigation was the problem of survival and functioning of embryonal substantia nigra (SN) neurons, taken from four species, implanted into the lateral ventricle of rats with denervated striatum. The recipients were 100 inbred rats of the Fisher 344 strain in which hemiparkinsonism was induced by unilateral chemical (6-OHDA) lesion of SN. As donor served foetuses of rabbits, hamsters, mouse CF1 and Sprague-Dawley rats. Immunosuppressive drugs were not applied. The effectiveness of the transplants was estimated by testing the rotational behaviour before and after transplantation over a period of 8 weeks at weekly intervals. Survival of the transplant was evaluated by histological and immunocytochemical methods. Behavioural tests demonstrated a statistically significant improvement persisting in groups of xenografts for three to five weeks. Histological investigations revealed that the time of graft survival corresponds roughly to the period of improvement in the rotational behaviour. The results indicate that without application of immunosuppressive drugs intracerebral transplant between different species survive no more than several weeks. Thus, it is necessary to search for homogenic material for therapeutic transplantations in parkinsonian patients.

Animals↗
PubMed1989

[Effect of histological technics on the volume and weight of various brain structures of rats at the early stages of life].

The aim of the studies was to elaborate technical procedure of material preparation for quantitative studies and determination of correction coefficients of morphometric parameters in dependence on histological procedures. Moreover, volume changes of the rat substantia nigra and striatum (structures degenerating in Parkinson's disease) during the first half year of life were estimated. As fixatives 4 and 8% formaldehyde in 4 and 20 degrees C were used. Irrespective of applied variant of fixation formaldehyde produced during first 48 hrs rapid increase of the brain weight and volume up to 52% of that of the fresh brain, which was followed by slow decrease of brain weight of about 1-3%/24 hrs. The most pronounced changes caused 4% formaldehyde in 20 degrees C. The best conditions for morphometric studies were obtained with the use of 8% formaldehyde in 20 degrees C. Dehydration in ethyl alcohol produced violent decrease of brain volume and weight (from 32% up to 39% of the fresh brain weight). Clearing in methyl bensoesane increases again the brain weight by a few percentage. The obtained results make possible to estimate error size in morphometric studies conducted on the formaldehyde-fixed material. It was stated also that the above histological procedure causes more pronounced changes in fetal rat brain and in brain of 1-2-day-old rats. Stabilization of changes caused by histological procedure is achieved between first and sixth months of rat life.

Age Factors↗
PubMed1982

The influence of ethanol intoxication on cholinergic axon terminals in the rat brain. (Morphometric evaluation).

In view of the inhibitory influence of ethanol on synaptic transmission demonstrated by numerous authors, the present investigations were undertaken with the purpose of ascertaining the ultrastructural changes in the cholinergic axon terminals of the CNS caused by chronic ethanol intoxication. The experiments were made with 12 rats receiving ethanol according to RATCLIFFE'S model (1972) in increasing doses over a period of 1, 2 and 3 months. The studies comprised evaluation of the electronmicroscopic picture of synapses from the temporal cortex and morphometric analysis of the number of synaptic vesicles in the boutons, of the surface area of synapse cross sections and the surface area of the cross sections of mitochondria in the boutons. Morphometric analysis showed that chronic administration of ethanol to rats reduces the number of synaptic vesicles in the boutons, which may be caused by chronic excitation of neurons by ethanol. Impairment of mitochondria within the synaptic boutons was also noted, probably due to disturbances in cell respiration produced by ethanol. Polymorphism of synaptic vesicles was observed in the form of greatly enlarged ones. It may be interpreted as the morphological manifestation of the process of axon terminals degeneration. Moreover, planimetric analysis demonstrated a significantly increased surface area of synaptic bouton cross sections in all experimental rats as compared with the control ones. The dynamics of the observed changes was not uniform. The reduction of the number of synaptic vesicles and impairment of mitochondria were most pronounced in the early phase of intoxication. In the later period in spite of increased doses and prolonged time of ethanol treatment the changes became rather less intensive, this probably being connected with the process of adaptation. Polymorphism of the synaptic vesicles became more pronounced gradually in the successive experimental groups, probably with corresponding advancing degeneration of the axon terminals. The significantly enlarged surface area of the synaptic boutons cross sections did not show any dependence on the connection of ethanol and duration of its administration.

Acetylcholine↗
PubMed1981

Ultrastructural and morphometric investigations on the mechanism of neurotransmitter release from synaptic vesicles.

The mechanism of neurotransmitter release from synaptic vesicles as the results of neuron excitation is not quite clear. It is believed, that this process may occur by way of exocytosis into the synaptic cleft directly from the cytosol to the cleft. Ultrastructural-morphometric analysis was attempted of the synaptic vesicles from the motor cortex of mice. As stimulation model an audiogenic epileptic seizure was used. The method of ZIO impregnation was applied, which according to Kawana (7) allowed to visualise the presence of a neurotransmitter in synaptic vesicles. Morphometric analysis consisted in counting the synaptic vesicles ZIO-positive, filled with neurotransmitter, and ZIO-negative, empty ones, in 3 successive zones of the synaptic bouton in the initial and end phases of seizures. As the result of excitation the number of ZIO-positive-synaptic vesicles diminished significantly whereas the number of ZIO-negative ones did not increase proportionally. This indicates that the "dark" vesicles do not change into the "clear" ones, but they disappear completely. The applied method did not allow us to precisely establish vesicle translocation toward the synaptic cleft. Nevertheless the considerable reduction of their number with the percentual distribution of vesicles remaining the same within the particular zones of bouton, may indicate, under the assumption of translocation of vesicles, that they disappear close to the cleft, probably by way of exocytosis.

Animals↗
PubMed1980

Ultrastructural and biochemical studies of the brain and other organs in rat after chronic ethanol administration. III. Influence of ethanol intoxication on oxidative phosphorylation of the rat brain mitochondria with ultrastructural and morphometric evaluation of mitochondrial fraction).

The effect of chronic ethanol intoxication on oxidative phosphorylation in the rat brain mitochondrial fraction was examined. Moreover, electron microscopy was used to verify the quantitative composition of the fraction and for examination of ultrastructural changes in the mitochondria. The experiments were carried out with 60 rats receiving, beside the normal diet, ethyl alcohol according to a modified RATCLIFFE model. In isolated rat brain mitochondria the NAD-dependent oxidation of substrates (glutamate + malate) was decreased. The phosphorylation index ADP/0 and the respiratory control ratio (RCR) in rat brain mitochondria from ethanol-treated rats were unchanged in the presence of both succinate and glutamate + malate. Chronic ethanol feeding did not induce any changes of succinate dehydrogenase and cytochrome oxidase activities in solubilised mitochondria fractions of rat brain. Electron microscopy studies revealed that mitochondria from control animals retained their outer and inner membranes, whereas those from rats given ethanol were almost always swollen and some were disrupted. In mitochondrial fractions isolated from ethanol-intoxicated rats an increase was observed of contaminating elements i.e. axons and synaptosomes of various sizes. It should be stressed that the mitochondria located inside synaptosomes and axons were unchanged. The composition of the fractions was quantitatively evaluated and confirmed the diminution of "free" mitochondria in the experimental fractions in favour of "bound" mitochondria which mainly occurred in the synaptosomes with preserved metabolic activity. On the basis of electron microscopy studies it could be suggested that ethanol intoxication causes the damage of some mitochondria, which become more sensitive to mechanical destruction during isolation procedure, and they do not sediment together with the fraction of normal ones. The absence of "free" mitochondria in pellets explains the spurious lack of disturbances in the energy metabolism of brain mitochondria after chronic ethanol intoxication.

Adenosine Diphosphate↗