PubMed Health⌕ Search

Biomedical subjects

E Madarasz

Publications and source records attributed to E Madarasz.

4 recordsLinked to original sources
PubMed1995

Differentiation is induced in three-dimensional cultures of brain cells immortalized by the LAP mammalian regulatory system.

Immortalized neuroectodermal precursor cell lines were generated from mouse brain by the SV40 large T antigen expressed under the control of the LAP (lac activating protein) mammalian regulatory system. The LAP system permits the reversible expression of T antigen as a function of the exogenous inducer, isopropyl-beta-D-thiogalactopyranoside. Immortalized cells can be stably maintained in an undifferentiated state in monolayer cultures. Cell lines expressed the early neurofilament-like protein nestin, but not markers characteristic for mature cells such as the neurofilament light protein and glial fibrillary acidic protein. Downregulating the LAP-controlled T antigen with isopropyl-beta-D-thiogalactopyranoside was not sufficient to induce differentiation. However, when cells formed three-dimensional aggregates, differentiation to a neuronal phenotype occurred, indicating that cell-cell interaction plays an important role in their differentiation. Cells in aggregates did not proliferate, even in the presence of T antigen, suggesting that an aggregation-induced signal to cease growth was dominant over the growth signal of T antigen. Further morphological differentiation was induced by basic fibroblast growth factor. These immortalized cells should facilitate molecular and cellular studies concerned with the mechanism of commitment, fate determination, and mitotic arrest of neuronal precursor cells in the developing mammalian CNS.

Animals↗
PubMed1991

In vitro formation of type 2 astrocytes derived from postnatal rat hypothalamus or cerebral cortex.

The origin and function of type 2 astrocytes in the optic nerve are now well described, but there are few and controversial observations concerning their origin and functional significance in other regions of the mammalian brain. We here describe primary and highly enriched secondary glial cultures obtained from postnatal (P0-P6) rat hypothalami and cerebral cortices that included glial cells with morphological and immunocytochemical characteristics of type 2 astrocytes. The somata of such astrocytes were characteristically small and polygonal; they bore several processes with few branches. They were highly immunoreactive for glial fibrillary acidic protein and the surface antigens, A2B5 and NSP4; they were immunonegative for myelin basic protein and galactocerebroside. They grew on top of a continuous monolayer of much larger, flattened cells, that were glial fibrillary acidic protein-positive but A2B5- and NSP4-negative. In cultures derived from tissues younger than postnatal day 4, their appearance required the addition of adult (horse) serum to the culture milieu; they appeared spontaneously in cultures from older animals. Analysis of the origin of these cells, including experiments using tritiated thymidine incorporation, indicated that these astrocytes resulted from asymmetric divisions of the flat glial cells in the basal layer of the cultures. After their first appearance which varied according to the age of the source tissue, they were continuously generated, with a generation time no longer than 48 h; the life-span of individual cells was found to not exceed one week in neuron-free primary glial cultures. They displayed important process motility but did not show any significant migratory activity. The ready inducibility of glial cells showing many characteristics of type 2 astrocytes, in cultures derived from different brain areas, suggests that type 2-like astrocytes or their committed precursors are not restricted to particular neural structures, but are probably widely distributed within the mammalian brain. Their functional significance within the different brain areas remains to be determined.

Animals↗
PubMed1984

Cell production and morphological pattern formation in primary brain cell cultures. I. Pattern formation within the basal layer(s).

Spontaneous pattern formation within the basal cellular layer of primary brain cell cultures were studied. Basal cells were found to be organized into a limited number of morphologically well distinguishable types of cell-arrangements. Phase contrast microscopy was used to characterize the different cell-assemblies morphologically. Under standard culture conditions the time of appearance and specific changes of relative frequency in time were also characteristic of different patterns. The distribution of mitotically active cells among the different morphological patterns within the basal layer was also investigated by recording [3H]thymidine uptake of cells. Reduction of mitotic activities of cells in the basal layer was found in the vicinity of overlying cells. In a given area of cultures the reduction of mitotic activity was proportional to the number of overlying cells. The influence of cell proliferation on the morphological pattern formation in primary cultures is discussed.

Animals↗