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Biomedical subjects

S Fedoroff

Publications and source records attributed to S Fedoroff.

At least 19 recordsLinked to original sources
PubMed1992

Immuno-electron microscopical localization of vimentin and glial fibrillary acidic protein in mouse astrocytes and their precursor cells in culture.

Immuno-electron microscopy was used to localize the distribution of vimentin and glial fibrillary acidic protein (GFAP) in mouse astrocytes and their precursor cells in primary cultures. In astroblasts and astrocytes, vimentin and GFAP form intermediate filaments (IF), which are heteropolymers, as previously observed in gliomas. Astrocytes and their precursor cells may have IF composed of GFAP-vimentin heteropolymer or vimentin alone, but IF composed of GFAP only were not seen. It seems that the formation of IF that are GFAP-vimentin heteropolymers is a feature of normal astroglia development and that the ratio of GFAP to vimentin in these IF reflects the degree of differentiation and functional state of the cell.

Animals↗
PubMed1992

Short-term response of brain tissue to cerebrospinal fluid shunts in vivo and in vitro.

The purpose of the studies was to determine how gross physical characteristics of cerebrospinal fluid (CSF) shunts and the cellular proliferative response to shunts contribute to shunt obstruction. Ventricular catheters with round holes, slots, and flanges were implanted into the lateral ventricles of rabbits for 4 weeks. All shunt designs were subject to ingrowth of tissue from the ventricle wall or choroid plexus. There were no qualitative or quantitative differences between normal and hydrocephalic rabbits. Astroglial cells from newborn mice were cultured on shunt catheters for 2 or 4 weeks. The growth of these cells was poor, probably because the cells cannot attach well to the silicone rubber substrate. Contact between the shunt catheter and vascularized brain tissue is the most important factor in the genesis of shunt obstruction.

Animals↗
PubMed1992

Morphology of astroglia in colony cultures following transient exposure to potassium ion, hypoösmolarity and vasopressin.

Brain swelling is the major cause of delayed neuronal damage following injury to the central nervous system. Swelling of mouse astroglial cells was studied in colony cultures by light and electron microscopy. Swelling of suspended astroglial cells was studied by flow cytometry. Swelling caused by hypoösmolarity solution was more pronounced than that caused by 15 or 60 mM K+. Under both conditions swelling in both immature and mature astroglia was followed by a regulatory volume decrease. Arginine vasopressin caused mild astroglial swelling and atrial natriuretic peptide did not significantly affect cell volume. All changes in extracellular environment were associated with changes in the morphology of microvilli and varying amounts of membrane ruffling. Immature cells exhibited a delayed response to the application of atrial natriuretic peptide and less membrane ruffling following exposure to 60 mM K+ than mature astroglia. These nonspecific morphological changes are likely associated with changes in membrane ion pump activity.

Animals↗
PubMed1991

Immunolocalization of the alpha isoform of smooth muscle actin in mouse astroglia in cultures.

In mouse astroglia colony cultures, cells display dramatic changes in their 'social behavior' during differentiation. The non-motile glioblasts progress through highly motile pro-astroblast and astroblast stages before becoming non-motile fibrous astrocytes. These changes in the behavior of astroglia are paralleled by changes in the organization of their microfilaments. Immunofluorescence staining of the astroglia colony cultures with rhodamine phalloidin, which binds to actin filaments (F-actin) formed by any of the 6 actin isoforms and with monoclonal antibody to alpha-smooth muscle (alpha-sm) actin (an actin isoform typical of smooth muscle cells), shows that the majority of the cells are positive for both alpha-sm actin and F-actin. Approximately 15% of the cells, however, were negative for alpha-sm actin but stained positively for F-actin, indicating that the actin of these cells belongs to isoforms other than the alpha-sm isoform.

Actins↗
PubMed1991

Macrophage-like cells originate from neuroepithelium in culture: characterization and properties of the macrophage-like cells.

Cultures of astroglia from C3H/HeJ mice, which are resistant to bacterial cell wall polysaccharide (LPS), initiated from embryos of Theiler stage 14 (9 days of gestation) up to Theiler stage 25 (17 days of gestation) as well as newborn animals, when subjected to nutritional deprivation, i.e. non-feeding of cultures, form large numbers of macrophage-like cells. These cells express Mac-1, Mac-3, F4/80 and Fc antigens. The cells are negative for GFAP, positive for vimentin, express Ia antigen and take up DiL-Ac-LDL. They are positive to non-specific esterase, secrete lysozyme and are phagocytic. Their morphology and ultrastructure closely resemble those of macrophages. Cultures initiated from neuroepithelium of Theiler stage 13 (8.5 days of gestation), before vascularization, when subjected to nutritional deprivation, also produce macrophage-like cells. Using spleen colony assay and methyl cellulose cultures, we were unable to detect the presence of hemopoietic (macrophage) precursor cells in astroglia cultures. This supports the hypothesis that the macrophage-like cells are of neuroectodermal origin and probably correspond to resident microglia of the CNS. Using nutritionally deprived astroglia cultures, a procedure was developed for isolation of macrophage-like cells and production of highly enriched macrophage-like (microglia) cultures.

Animals↗
PubMed1990

Developmental transition in plasticity properties of differentiating astrocytes: age-related biochemical profile of plasminogen activators in astroglial cultures.

Plasminogen activator (PA) is a key enzyme in control of the cascade of extracellular proteolytic activities, proteases that degrade the extracellular components. Mammalian cells produce two molecular forms of PA, the urokinase type (u-PA) and the tissue type (t-PA); the u-PA type enzyme regulates cell migration/invasion and related tissue plasticity events. Thus, these plasticity properties of cells are defined by their PAs' biochemical profiles. The capacity of the differentiating glial cells of the central nervous system (CNS) to express and regulate the two types of PA activities has been examined as a function of cell age in culture. Results of the study suggest that only the immature astrocyte is endowed with these plasticity properties. Differentiating heterogeneous rat glial cells in culture express PA activity. Astroglia were identified as the primary source for the glial PA activity, as no PA activity was detected in the purified oligodendroglia. Cellular PA activity levels of differentiating rat and mouse astroglia are developmentally regulated. The specific activity of PA reached its highest level in rat astroglia at a cell age corresponding to 20-32 postnatal days (P20-P32) and in mouse astroglia at P8-P14; thereafter, this declined (three- to fourfold decrease) within 2 weeks to a low value. At comparable ages (P0-P35), the magnitudes of the PA specific activities of the differentiating rat astroglia and of the developing cerebrum, the tissue from which these cells were purified, were similar. Differentiating rat astroglia produce u-PA and t-PA, the cellular content of both is developmentally regulated, and the u-PA form is only found in the immature cells. u-PA is the predominant form in the immature astrocyte until age P13. Both forms are found in cells at ages P14-P30, and at later stages u-PA disappears while the t-PA type persists as the sole form. After 3 more weeks neither of the PA types was detected. Astroglia express also PA inhibitory activity; the rat astroglial PA inhibitor (PAI) seemed to be identical to PAI-1, one of the known types of PAIs. Stimulation of astroglial proliferation by their subculturing in contrast to Schwann cells did not lead to an increase; rather, beyond a certain cell age (P13) it resulted in a threefold irreversible decline in the PA specific activity of the daughter cells. It has been established that various biochemical properties of CNS mature glia appear on schedule with cell age in culture, thus defining "mature"glia in vitro.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

The relationship of expression of statin, the nuclear protein of nonproliferating cells, to the differentiation and cell cycle of astroglia in cultures and in situ.

Cells in the quiescent, nonproliferative state express a protein, statin, in their nuclei. When the cells reenter the cell cycle, statin disappears and another protein, cyclin, appears. We have examined mouse astroglia at various stages of differentiation in cultures and astroglia in adult mouse brains for the presence of statin. In cultures initiated from the neopallium of newborn mice, the glial fibrillary acidic protein (GFAP)+ stellate astrocytes were statin-negative (statin-) but cyclin-positive (cyclin+). In the same cultures, large flat cells (senescent cells) were statin+ but cyclin-. In frozen sections of the brains of adult mice and in brain smears, GFAP+ astrocytes were statin-. Neither stellate astrocytes grown in cultures for 30 or more days nor astrocytes in adult mouse brain were labeled when pulsed with bromodeoxyuridine (BudR). When astroglia were treated with dibutyrl cyclic adenosine monophosphate (dBcAMP), large stellate cells that closely resemble reactive astrocytes in situ formed. These cells were all statin+ from 11-62 days in vitro; however, reactive astrocytes in mouse neopallium, 4-50 days after a stab wound, were statin-. In colony cultures, senescent cells became statin+, whereas stellate astrocytes and their precursor cells remained statin-. These observations indicate that normal astrocytes both in cultures and in situ retain the potential to divide and probably progress through the cell cycle at a very slow rate.

Animals↗
PubMed1990

Production of colony-stimulating factor-1 (CSF-1) by mouse astroglia in vitro.

We investigated whether astroglia produce any of the known macrophage growth factors, CSF-1, GM-CSF, and IL-3, and if so, whether any of these cytokines stimulate the growth of CNS macrophages. In this work we used highly enriched cell cultures of C3H/HeJ mouse neopallium: cultures of astroglia and cultures of macrophage-like cells derived from nutritionally deprived astroglia cultures. We found that astroglia in cultures accumulate in the medium, an activity that stimulates the proliferation of macrophage-like cells. The activity has been identified as CSF-1 by using growth assays of cells dependent and nondependent on CSF-1, and by radioreceptor analysis which is highly specific for CSF-1. Northern blot analysis demonstrated the presence in astroglia of CSF-1 mRNA and the presence of CSF-1 receptor (c-fms) mRNA in macrophage-like cells but not in astroglia. The astroglia did not produce GM-CSF or IL-3. We concluded that a paracrine relationship exists between astroglia production of CSF-1 and the response of macrophage-like cells to the cytokine in culture.

Animals↗
PubMed1990

Swelling of astroglia in vitro and the effect of arginine vasopressin and atrial natriuretic peptide.

Numerous neuropathological conditions are accompanied by astroglial swelling which may contribute to secondary neuronal damage. From 4-27 days in vitro, swelling of astroglial cells was induced by hypo-osmolar solutions and high K+ solutions and the cells were examined by microscopy and flow cytometry. Regulatory volume decrease was observed beginning after approximately 30 minutes and was accompanied by increased membrane activity. Arginine vasopressin caused gradual persistent astroglial swelling. Atrial natriuretic peptide caused retraction of the astroglial cell processes but did not significantly alter the swelling induced by hypo-osmolar or elevated K+ solutions. The membrane mechanisms responsible for the control of astroglial cell volume did not appear to be specific for mature astroglia, rather they are present at all developmental stages.

Animals↗
PubMed1989

A 48 kilodalton intermediate filament associated protein (IFAP) in reactive-like astrocytes induced by dibutyryl cyclic AMP in culture and in reactive astrocytes in situ.

In this paper we demonstrate that the 48 kilodalton (kDa) intermediate filament associated protein (IFAP), previously reported to be present in normal astrocytes, is also present in reactive astrocytes in situ and in reactive-like astrocytes induced by dibutyryl cyclic AMP in vitro. This IFAP is detectable by antibodies in normal rabbit serum (F2N) and is closely associated with glial fibrillary acidic protein-containing intermediate filaments (IF). The expression of 48 kDa IFAP is related to the acquisition of stellate shape by normal and reactive-like astrocytes in vitro. It is proposed that 48 kDa IFAP may be responsible for cross-linking IF into bundles and is thereby associated with cell process formation.

Animals↗
PubMed1988

48-Kilodalton intermediate-filament-associated protein in astrocytes.

We provide evidence that a protein of 48 kilodaltons (KD), recognized by a normal rabbit serum (F2N), is associated with intermediate filaments (IF) of astrocytes both in cell cultures and in situ. Immunofluorescence staining shows that the F2N serum gives a fibrous staining pattern similar to that seen with anti-serum to glial filament protein (GFP), a protein specific for IF of astrocytes, and that both proteins are present in the perinuclear fibrous aggregates of IF produced by treating the cells with colchicine. At the ultrastructural level the gold particles decorating the 48-KD protein are localized in clusters along the IF, whereas the gold particles decorating the GFP are localized on the IF in a linear pattern. This difference in distribution and the fact that the two proteins have different electrophoretic mobilities on SDS gels indicates that the 48-KD protein although associated with IF is different from GFP. The 48-KD protein appears to be a distinct, developmentally regulated intermediate-filament-associated protein (IFAP), different from other IFAPs reported to date and the first IFAP described in astrocytes. Its appearance in late developmental stages when motile astroblasts are changing into nonmotile stellate cells suggests that the 48-KD protein may be involved in cross-linking the GFP-containing IF to provide more tensile strength to the cytoplasm at the expense of flexibility.

Animals↗
PubMed1979

The development of mouse spinal cord in tissue culture. I. Cultures of whole mouse embryos and spinal-cord primordia.

Whole mouse embryos were grown in vitro from Theiler stage 12 (1 to 7 somites) to Theiler stages 15 and 16 (25 to 35 somites). This procedure gives experimental access to precisely staged embryos during the early period of neurogenesis. To follow the further development of neurons in vitro, fragments of spinal primordia were set up from these cultured embryos. In such cultures, the proliferation of precursor cells, the formation of postmitotic cells, and, finally, the cytodifferentiation of neurons were observed.

Animals↗
PubMed1979

Effect of horse serum on neural cell differentiation in tissue culture.

The effects of various concentrations of horse serum on dissociated mouse glial precursor cells in colony cultures were evaluated. High concentrations (20% or more) favored cell attachment but inhibited cell proliferation and differentiation, whereas lower concentrations (5% to 10%) favored cell proliferation and differentiation. In fetal bovine serum the cells did not attach to culture surfaces to the same degree nor did they achieve the same level of differentiation as in corresponding concentrations of horse serum.

Animals↗
PubMed1978

Kinetic characteristics of the glutamate uptake into normal astrocytes in cultures.

Kinetics for uptake and release of glutamate were measured in normal, i.e., nontransformed, astrocytes in cultures obtained from the dissociated, cortex-enriched superficial parts of the brain hemispheres of newborn DBA mice. The uptake kinetics indicated a minor, unsaturable component together with an intense uptake following Michaelis-Menten kinetics. The Km (50 micrometer) was reasonably comparable to the corresponding values in brain slices and in other glial preparations. The Vmax (58.8 nmol min-1 mg-1 protein) was, however, much higher than that observed in glial cell lines or peripheral satellite cells, and also considerably higher than that generally reported for brain slices. The release of glutamate was much smaller than the uptake, and only little affected by an increase of the external glutamate concentration, suggesting a net accumulation of glutamate rather than a homoexchange. Such an intense accumulation of glutamate into normal astrocytes may play a major role in brain metabolism and may help keep the extracellular glutamate concentration below excitatory levels.

Animals↗
PubMed1978

The development of chick spinal cord in tissue culture. II. Cultures of whole chick embryos.

By using whole-chick-embryo cultures followed by fragment cultures of spinal-cord primordia, it was possible to reproduce in vitro the whole process of neuronal development beginning with its initiation and continuing up to and including the maturation of neurons. Normal whole embryos were developed to Hamilton-Hamburger stages 17 and 18 by growing embryos from the primitive streak stage on large (28-mm) glass rings. The advantage of whole-embryo cultures is that development can be staged accurately, which is especially important during the early stages when morphogenesis progresses very rapidly. By using such accurately staged embryos and tritiated thymidine, we have determined that some postmitotic neuronal precursor cells appear in chick embryos as early as Hamburger-Hamilton stages 4 and 5, i.e. the definitive streak stages before the neural tube has formed.

Animals↗
PubMed1978

An audiovisual program in cell biology.

Cell biology has been divided into 19 topics for the purpose of planning audiovisual materials. One of these topics, the structure and function of cell membranes, has been developed as a series of seven self-instructional slide-tape units and tested in five medical schools. Organization of advisers, analysis and definition of objectives and content, and development and evaluation of scripts and storyboards are discussed.

Audiovisual Aids↗