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B Pettmann

Publications and source records attributed to B Pettmann.

50 records · Page 3Linked to original sources
PubMed1987

Neuronal-derived factors regulating glial cell proliferation and maturation.

We purified to homogeneity two active factors, named astroglial growth factors (AGFs: AGF2 and AGF1), from bovine brain after two and three chromatographic steps, respectively. We found that AGFs have a strong affinity for heparin. Therefore, heparin affinity chromatography was used to purify rapidly and efficiently these growth factors. The purified AGF1 is an acidic protein (pI: 5.5) with an apparent molecular weight of about 17,500 daltons; the AGF2 is a basic protein (pI: 9.5) of 18,500 daltons. The comparison of the physico-chemical properties, the aminoacid composition and the amino-terminal sequence of the AGFs with that of other growth factors isolated from the brain and affecting the proliferation of other cell types has indicated that AGF1 and AGF2 are identical to the acidic and basic fibroblast growth factor (FGF), respectively. Both factors stimulate the proliferation as well as the morphological and biochemical maturation of the astroglial cells. Both factors enhance also the multiplication of oligodendroglial cells. Polyclonal and monoclonal antibodies against AGFs have been prepared and used for immunocytochemical localization of these molecules in the rat brain and cerebellum. AGFs are found exclusively in neuronal cells.

Animals↗
PubMed1986

Decrease in the density of orthogonal arrays of particles in membranes of cultured rat astroglial cells by the brain fibroblast growth factor.

The effect of brain-derived basic fibroblast growth factor (bFGF) on the membrane structure of cultured rat astroglial cells was investigated by quantitative freeze-fracture replica examination. In the presence of bFGF the number of the orthogonal arrays of particles (OAP), which are characteristic compounds of the membrane of mammalian astrocytes, is clearly reduced. This finding is discussed in the framework on current views about neuro-glial interactions and their implications in the process of fiber regeneration in the central nervous system.

Animals↗
PubMed1986

The brain fibroblast growth factor (FGF) is localized in neurons.

The physiological role of fibroblast growth factor (FGF), like many other characterized growth factors, is poorly understood. Therefore, it would be useful to know in which cell type this growth factor is present. Using monoclonal and polyclonal antibodies against FGF, we have localized this molecule in rat brain. Interestingly, FGF is found exclusively in neuronal cells. Since FGF stimulates the proliferation and maturation of glial cells in vitro, its involvement in the interaction between neuronal and glial cells in vivo is likely. A role in the triggering of reactive gliosis can also be hypothesized.

Animals↗
PubMed1986

Primary culture of rat ependymal cells in serum-free defined medium.

We have developed a serum-free chemically defined medium which allows the obtainment of a primary culture highly enriched in ciliated ependymal cells. Serum was never used. Mechanically dissociated neonatal rat brain hemisphere cells were seeded on a fibronectin substratum. Culture medium was minimum Eagle's medium until day 14 in vitro and Waymouth's MD 705/l medium thereafter. Both media were supplemented with insulin (5 micrograms/ml), transferrin (10 micrograms/ml) and fatty acid-free bovine serum albumin (0.5 mg/ml). In these conditions, without addition of growth factors, the culture was enriched in ependymal cells; with the addition of thrombin cell growth was stimulated and moreover a nearly pure culture of ependymal cells was obtained. In this very simple culture medium, cells looked healthy up to two months after seeding and about 75% of the cells were ciliated. In a fraction of these cells the glial fibrillary acidic protein, a protein specific for astroglial cells in the central nervous system, was immunohistochemically revealed. The availability of an almost pure primary culture of ependymal cells will make many studies possible on this cell type, particularly studies on the development of these cells, on the regulation of their genetic expression and on their physiological function.

Animals↗
PubMed1985

Purification of two astroglial growth factors from bovine brain.

The astroglial growth factor (AGF), which induces a characteristic morphological change in cultured rat astroglial cells and stimulates their proliferation, was purified to homogeneity from bovine brain. Two different methods were used, the second one including heparin-Sepharose affinity chromatography. AGF is actually composed of two factors, AGF1 and AGF2, which both modify the morphology and stimulate the proliferation of the astroglial cells. Several data suggest that the AGFs are similar or possibly identical to the fibroblast growth factors (FGFs) isolated from brain [(1984) Proc. Natl. Acad. Sci. USA 81, 357-361; and 6963-6967]. A specific antiserum against AGFs was raised in mouse.

Amino Acids↗
PubMed1983

An immunohistochemical study of two myelin-specific proteins in enriched oligodendroglial cell cultures combined with an autoradiographic investigation using [3H]thymidine.

The aim of the present work was to examine the possible relationship between proliferation and expression of 2 myelin specific proteins in cultured oligodendroglial cells. Mixed cultures of glial cells, from newborn rat brain, containing astroglia and oligodendroglia were grown in 2 different culture media, minimum Eagle's medium and Waymouth's medium both supplemented with 10% calf serum in presence or absence of adult rat brain soluble extract. The proliferative activity of the cells was followed over a 28-day period by autoradiography after radioactive thymidine incorporation. It was found that in cultures grown in Waymouth's medium the proportion of oligodendroglial cells was higher and that proliferation was more active than in minimum Eagle's medium. Addition of brain extract elicited a stimulation of the proliferation of the cells in the 2 basal media. Under all conditions W1 protein appeared earlier than MBP by immunofluorescent visualization. Some oligodendroglial cells synthesizing W1 protein were still able to proliferate. MBP appears to be a marker of a later stage of cell maturation since very few MBP-positive cells incorporated tritiated thymidine. More cells contained MBP in the presence of brain extract. These results suggest that oligodendroglial cell maturation proceeds by steps, the step of W1 protein expression is compatible with proliferation while that of MBP expression appears at the end of the proliferation phase.

Animals↗
PubMed1982

Stimulation of proliferation and maturation of rat astroblasts in serum-free culture by an astroglial growth factor.

Astroblasts from brain hemispheres of newborn rats were cultivated for 5 days in a complete medium containing 10% fetal calf serum. Cultures were then grown in basal medium in absence of serum. In these conditions, after 15 days only a few cells remained. When the basal culture medium was supplemented with insulin and transferrin (IT medium) the number of the remaining cells was twice higher. However, it was still lower than that found in the 5-day cultures before serum was removed. Thus the IT medium does not allow a good survival of the cells. Addition to the medium of an astroglial growth factor (AGF) from bovine brain soluble extract led to a tenfold increase of the cell number compared to cultures maintained in the basal medium alone. Effects of the factor on cell survival and on proliferation were examined independently. It was found that the factor did not greatly increase the survival of the cells but that it stimulated the proliferation. Addition of the growth factor to the IT medium elicited an increase of the level of S-100 protein and of the activity of glutamine synthetase, two proteins which are specific to astroglial cells in the central nervous system. These results indicate that the astroglial brain factor allows growth and maturation of the rat astroblasts maintained in serum-free medium.

Animals↗
PubMed1981

Developmental changes in cultured neurones from chick embryo cerebral hemispheres. An ultrastructural and neurochemical study.

The acquisition of ultrastructural and neurochemical properties was studied during the development of neurones from 8-day-old chick embryo cerebral hemispheres, cultivated on polylysine-coated surfaces. The first contacts suggestive of synaptic profiles were observed after 3 days of culture. From the 6th day, junctions with significant thickening of the postsynaptic element and many presynaptic vesicles could be seen. Synaptic endings contained predominantly dense-cored vesicles. These cultured neurones acquired dopaminergic properties during their development: (1) 95% of the cells exhibited glyoxylic acid-induced fluorescence; (2) tyrosine hydroxylase and dopa decarboxylase activities were present and increased with time in culture, but dopamine-beta-hydroxylase activity was undetectable. Choline acetyltransferase activity remained at a very low level at all stages of culture. It is suggested that when cultured in the total absence of glial cells, the neurones of embryonic chick cerebral hemispheres give no evidence of cholinergic mechanisms, but display a number of dopaminergic characteristics.

Acetylcholinesterase↗
PubMed1981

Effects of brain extracts from chick embryo on the development of astroblasts in culture.

Different soluble extracts were prepared from chick brains and tested for their effect on the development of glial cells prepared from the cerebral hemispheres of newborn rats and grown in primary culture. Every brain extract tested, from animals between 8 days embryonic and adult ages, stimulated astroblast proliferation and accelerated their maturation as shown by morphological changes, the appearance of gliofilament bundles and by the increase of the amount of the glial-specific protein S-100 between 10 and 40 days in culture. These effects were observed in cultures continuously treated with extracts beginning with the 5th day after seeding. In cultures in which treatment was stopped 25 days after seeding, S-100 level continued to increase like in continuously treated cells. An identical increase of S-100 protein level was induced by treatments started as early as 24 h or as late as 25 days after seeding. In contrast, when the extracts were added at time 0 a toxic effect was observed and no stimulation of the maturation occurred.

Animals↗