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Biomedical subjects

J Spacek

Publications and source records attributed to J Spacek.

At least 73 records · Page 4Linked to original sources
PubMed1987

Ultrastructural pathology of dendritic spines in epitumorous human cerebral cortex.

Ultrastructural changes in the human epitumorous cerebral cortex were examined. A swelling of nerve cell perikarya, dendrites and axon terminals, and an occasional hyperplasia and disarray of microtubules and neurofilaments were observed. Accumulations of lysosomes, tubuloreticular structures and intracytoplasmic or intramitochondrial crystalloid inclusions were also found. Some myelinated axons were degenerated. Astrocytes and their processes were focally swollen. A mild swelling was found also in microgliocytes. Oligodendrocytes occasionally contained accumulations of dense bodies. Special attention was paid to dendritic spines. The spine surface morphology changed distinctly on swollen dendritic segments. The necks of most spines were short and wide, and numerous sessile forms were present in this location. The spine apparatus was often hypertrophied and disorganized. Smoothing out of spines on swollen dendrites is described and a possible functional significance of the observed changes in the symptomatology of brain tumors is hypothesized.

Animals↗
PubMed1986

Melanotic neuroectodermal neurocranial tumor of infancy of extra-intra-and subdural right temporal location: CT examination, surgical treatment, literature review.

A melanotic neuroectodermal neurocranial tumor of infancy of extra-intra-subdural right temporal location, examined by CT and successfully operated in a 33-month-old boy is reported in context with the literature. Out of 30 cases (including our case) of melanotic neuroectodermal neurocranial and intracranial tumors (MNNIT) 18 were located in the neurocranium (MNNT) and 12 intracranially, i.e. in the brain and cerebellum (MNIT). 23 tumors were located medially (11 at the anterior fontanel, one at the posterior fontanel, one in the 3rd ventricle, one in the sella turcica, one in the pineal region, 8 in the cerebellar vermis) and 7 laterally (five involved the temporal bone, one of which with intracranial propagation (our case), one in the temporal lobe of the brain, one in the skull posterior to the mastoid process). Twenty-eight cases were children (16 boys, 8 girls, four not stated), two adults. The location is important in respect to biology and surgery: MNNIT can be grouped as to its relation to the arachnoid barrier layer into malignant and benign. MNIT localised medially subarachnoidally are malignant. MNNT of small dimensions localised medially and laterally extraarachnoidally are benign. MNNT of extreme dimensions localised medially extra-intradurally are also benign, but difficult to treat. In the MNNT when diagnosed early and operated radically, the mortality can be lowered. Our case, presented on CT (1978) as first case of combined extra-intra-subdural location, represents the 173rd MNT and the 18th related to neurocranium.

Brain Neoplasms↗
PubMed1985

Three-dimensional analysis of dendritic spines. II. Spine apparatus and other cytoplasmic components.

A total of 342 dendritic spines (193 from the visual and 149 from the cerebellar cortex of the mouse) were analyzed in serial and several hundred of thousands of them in single sections, with respect to the presence and organization of the spine apparatus and other cytoplasmic components. The continuity of the spine apparatus with the smooth endoplasmic reticulum of the dendritic trunk was shown in three-dimensional reconstructions. The dense material of the spine apparatus was divided into "inner dense plate" and "outer dense plate". The close relationship between the outer dense plate and the postsynaptic density suggests that the spine apparatus functions as a postsynaptic protein synthesizing centre. The material from the outer dense plate could be used for a dynamic extension of the synaptic active zone. An extraspinous spine apparatus of the axon initial segment was partially reconstructed. Polyribosomes were found in all large spines of the visual cortex but were not so frequent in small spines and in Purkinje cell dendritic spines. Microfilamentous network and intermediate filaments occurred in the spines. The smooth endoplasmic reticulum of Purkinje cell dendritic spines was reconstructed. No spine apparatus and dense material were present in these spines.

Animals↗
PubMed1985

Three-dimensional analysis of dendritic spines. III. Glial sheath.

The glial envelope of dendritic spines in the visual and cerebellar cortices was evaluated by analysis of serial sections. Three-dimensional reconstructions of the protoplasmic astrocyte processes were made and the quantitative proportions of the glial cover on dendritic spines were measured and compared. Whereas dendritic spines on spiny branchlets of Purkinje cells are, with the exception of afferent axon terminals, completely covered by the glial sheath (74.44%), dendritic spines of pyramidal cells are only partially covered (28.89%), so that spine stalks and even synaptic clefts frequently lack glial isolation. A new, relatively frequent configuration of subsurface cistern--astrocyte process--dendritic spine is described. A possible functional significance of the differences in the glial ensheathment of dendritic spines in visual and cerebellar cortices is discussed.

Animals↗
PubMed1985

Relationships between synaptic junctions, puncta adhaerentia and the spine apparatus at neocortical axo-spinous synapses. A serial section study.

A total of 80 cotical axo-spinous synaptic junctions were reconstructed from serial sections and about 100,000 were analyzed in single sections. Special attention was paid to the occurrence of puncta adhaerentia associated with perforated, annulate or horseshoe-shaped (= complex) synaptic junctions and to the presence and proximity of the spine apparatus. Further evidence is presented that the spine apparatus has no relationship to simple (round or oval) synaptic specializations, but is present in association with at least 91% of complex junctions. The spine apparatus points towards the punctum adhaerens which in at least 71% of cases seems to be an integral part of the complex synapse. Direct continuity was found between the dense material of the spine apparatus and the punctum adhaerens. It is suggested, in accordance with other recent studies, that expansion of the synaptic active zone occurs by the addition and transformation of puncta adhaerentia. The spine apparatus may participate in this dynamic process as a possible donor of specific postsynaptic proteins.

Adult↗
PubMed1984

[Metastasizing basalioma at an early age].

The case is described of a woman who suffered since her early childhood from four foci of basalioma and died aged 29 years of metastatic lung involvement. The case appears unique comprising several rare features, e. g. a basalioma in childhood, a metastatic basalioma, and a small-sized metastasizing primary tumour. The disease may be congenital, however, it differs from the typical nevoid basal cell carcinoma syndrome.

Adolescent↗
PubMed1983

Three-dimensional analysis of dendritic spines. I. Quantitative observations related to dendritic spine and synaptic morphology in cerebral and cerebellar cortices.

A total of 212 dendritic spines (108 from the visual and 104 from cerebellar cortices of the mouse) were analyzed in serial sections. Dendritic spines (DS) and synaptic active zones (SAZ) were classified according to their shape, and the following quantitative data were measured: DS stalk and bulb diameters, DS length and volume, number of cisterns of the spine apparatus, DS and SAZ surface areas and their mutual proportions. Quantitative relationships between the spine apparatus and the size of DS and SAZ, between the volume and surface area of DS and between the size of DS and the size of SAZ were studied. Thin, mushroom-shaped and stubby DS with simple (circular or oval), complex (perforated, annulate or horseshoe-shaped) and multifocal SAZ were found on terminal branches of pyramidal cell apical dendrites and club-shaped DS with simple (circular or oval) SAZ on spiny branchlets of Purkinje cells. Statistically significant differences were found between all values measured on various DS types in the visual cortex. Linear dependencies of the DS surface area on DS volume and of the SAZ surface area on the DS surface area were established. Only a limited area of DS plasma membrane (7-10%) was occupied by SAZ. This finding indicates a possible functional importance of the SAZ/DS (and possibly also of the total SAZ/total postsynaptic membrane) surface ratio.

Animals↗
PubMed1982

Ribosome-associated membrane contacts between astrocytes in the anoxic brain.

Between adjacent astrocytes in cerebral and particularly cerebellar cortices of brains unsuccessfully perfused or subjected to 2-30 min anoxia or short (5 h) autolysis, a new distinct unusual variant of an intercellular apposition was observed, which derived from already pre-existing membrane contacts. This membrane apposition was characterized by thicker contacting plasma membranes than usual, narrower intercellular distance, a fine para- and intermembranous material and ribosomes in the paramembranous position. In addition to these ribosome-associated membrane appositions ribosomes-associated gap junction and microtubule-associated junction were observed in isolated cases. The reason for binding of ribosomes and microtubules to the plasma membrane and their function in this site is unknown.

Animals↗