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Biomedical subjects

G Neufeld

Publications and source records attributed to G Neufeld.

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

Basic fibroblast growth factor in human rhabdomyosarcoma cells: implications for the proliferation and neovascularization of myoblast-derived tumors.

Cultured human embryonal rhabdomyosarcoma cells express the basic fibroblast growth factor (bFGF) gene and they produce bFGF, which is apparently composed of two microheterogenous forms with Mrs of 16,500 and 17,200, respectively. bFGF derived from the rhabdomyosarcoma cells stimulates their own proliferation and that of human or bovine vascular endothelial cells. It is conceivable that the rhabdomyosarcoma-derived bFGF stimulates the growth and neovascularization of human rhabdomyosarcomas and that it may thereby contribute to the development of these tumors.

Animals↗
PubMed1987

Basic fibroblast growth factor as a growth inhibitor for cultured human tumor cells.

Basic fibroblast growth factor (bFGF) stimulates the proliferation of many cells and it is found in a wide variety of normal or transformed tissues. As demonstrated here, bFGF is also present in cultured human Ewing's sarcoma cells. Unexpectedly, however, bFGF isolated from these cells inhibits their own proliferation, indicating that bFGF can act as an endogenous (autocrine) growth inhibitor for cultured Ewing's sarcoma cells. Since bFGF also inhibits the proliferation of some further tumor cells, but stimulates that of others, it can be considered a bifunctional regulator of tumor cell proliferation. The autocrine growth-inhibitory effect of bFGF in Ewing's sarcoma cells may explain the low mitotic activity of Ewing's sarcomas.

Cell Division↗
PubMed1987

Basic fibroblast growth factor: production and growth stimulation in cultured adrenal cortex cells.

Cultured bovine adrenal cortex cells express the basic fibroblast growth factor (bFGF) gene and contain, but under normal conditions apparently do not release, bFGF. However, once released, bFGF can stimulate proliferation of the cells, indicating that it could act as a self-stimulating growth factor for adrenal cortex cells. It is conceivable that the intracellular bFGF is released upon injury of the adrenal cortex and that it may be involved in the subsequent tissue repair mechanisms by stimulating the proliferation of adrenal cortical and vascular endothelial cells.

Adrenal Cortex↗
PubMed1987

Bovine granulosa cells produce basic fibroblast growth factor.

Cultured bovine granulosa cells express the gene encoding basic fibroblast growth factor (bFGF). The bFGF gene is transcribed into 7.0- and 3.7-kilobase mRNA transcripts which are apparently translated into 16,000 mol wt bFGF-like growth factor. The granulosa cell-derived bFGF is bioactive, i.e. it can stimulate the proliferation of capillary endothelial or granulosa cells. This mitogenic effect is prevented by specific neutralizing anti-bFGF antibodies. Our results indicate that bFGF derived from granulosa cells can act as both autocrine and paracrine growth factor, and they further suggest that the factor may be involved in the development of the rich vasculature of the theca interna of the follicle.

Adrenal Cortex↗
PubMed1987

Basic fibroblast growth factor is present in cultured human retinoblastoma cells.

Cultured human retinoblastoma cells express the basic fibroblast growth factor (bFGF) gene and they produce material similar, if not identical, to bFGF. The retinoblastoma-derived bFGF can stimulate the proliferation of capillary endothelial cells and this process is inhibited by anti-bFGF antibodies. It is conceivable that the retinoblastoma-derived bFGF contributes to the neovascularization of retinoblastomas.

Cell Line↗
PubMed1986

Basic and acidic fibroblast growth factors interact with the same cell surface receptors.

Despite quantitative differences, the activity of basic and acidic fibroblast growth factors (FGF) on a wide variety of normal diploid cells derived from neuroectoderm and mesoderm is intrinsically similar. This suggests that they bind to the same cell surface receptors. This was investigated using a baby hamster kidney cell line (BHK-21) as a model. BHK-21 cell membrane components that interact with basic and acidic FGF have been identified by covalent cross-linking to their respective 125I-labeled ligands. Under appropriate conditions, basic and acidic 125I-FGF were cross-linked, using disuccinimidyl suberate, to two receptor species with apparent molecular masses of 145,000 and 125,000 daltons, respectively. The labeling of those receptors is inhibited when either native basic or acidic FGF are present in excess during incubation of cells with either acidic or basic 125I-FGF. Competition of basic 125I-FGF with increasing concentrations of native acidic FGF results in a preferential decrease in the labeling of the 125,000-dalton species, whereas competition of acidic 125I-FGF with increasing concentrations of native basic FGF leads to a preferential decrease in the labeling of the 145,000-dalton species. The data suggest that qualitatively both mitogens interact with the same 145,000- and 125,000-dalton receptor species. The different affinities displayed by acidic and basic FGF toward their common receptor molecules could explain why acidic FGF, depending on the cell type considered, is 20-100-fold less potent than basic FGF.

Affinity Labels↗
PubMed1986

Effect of lipoproteins and growth factors on the proliferation of BHK-21 cells in serum free culture.

Baby hamster kidney-derived cells (BHK-21 cell line), seeded at low density on gelatin coated dishes and exposed to a 1:1 (v/v) mixture of Dulbecco's modified Eagle's medium and Ham's F-12 medium, proliferate actively when exposed to high density lipoproteins (HDL), transferrin, and basic or acidic fibroblast growth factor (FGF). This serum free medium combination supported cell multiplication at a rate equal to that of serum supplemented medium, and at low cell input (10(3) cells/35-mm dish). Epidermal growth factor (EGF), although mitogenic for BHK-21 cells, was less efficient than either basic or acidic FGF in supporting cell growth. When the potency of basic and acidic FGF were compared, acidic FGF was 10-fold less potent than basic FGF. The requirement of BHK-21 cells for transferrin appears to be minimal since cells exposed to HDL and basic FGF could be serially transferred for at least 50 cumulative population doublings in the absence of transferrin.

Animals↗
PubMed1985

The identification and partial characterization of the fibroblast growth factor receptor of baby hamster kidney cells.

The binding of biologically active, 125I-labeled basic fibroblast growth factor (FGF) to baby hamster kidney-derived cell line cells (BHK-21) was studied at 4 degrees C. Unlabeled FGF displaced cell surface bound 125I-FGF, but platelet-derived growth factor, epidermal growth factor, insulin, or transferrin did not. Binding was saturable both as a function of time and as a function of increasing 125I-FGF concentrations. Scatchard analysis of the binding data revealed the presence of about 1.2 X 10(5) binding sites/cell with an apparent KD of 270 pM. The number of the binding sites was down-regulated following preincubation of the cells with FGF. The density of binding sites/cell also decreased as an inverse function of cell density. When 125I-FGF binding was studied in a BHK-21 cell membrane preparation, it was found that the membranal binding site displayed a lower KD of 21 pM. 125I-FGF was covalently cross-linked to its cell surface receptor on intact BHK-21 cells using the homobifunctional agent disuccinimidyl suberate. Two macromolecular species with an apparent molecular weight of 145,000 and 125,000, respectively, were labeled under both reducing and nonreducing conditions. Unlabeled FGF competed with 125I-FGF for binding to both macromolecular species. The labeling of the macromolecules was also inhibited by heparin. No labeling was observed in the absence of the cross-linkers or when heat-inactivated 125I-FGF was used instead of radiolabeled, biologically active FGF.

Animals↗
PubMed1983

Trapping of the beta-adrenergic receptor in the hormone-induced state.

Isoproterenol and other agonists readily dissociate from the beta-adrenergic receptor in turkey erythrocyte membranes. However, when a low concentration of deoxycholate is added, the receptor locks the prebound agonist; i.e., the rate of dissociation of the prebound agonist decreases drastically. The dissociation of prebound antagonists is slightly increased by deoxycholate. Locking, which is thus agonist specific, occurs in the cold, is reversed when detergent is removed from the membranes, and appears not to require the guanyl nucleotide binding protein of the adenylate cyclase system. It is suggested that this induced fit of a receptor to an agonist represents the specific conformational response that normally propagates in the receptor molecule in its interaction with the next component along the pathway of signal transmission.

Animals↗
PubMed1980

Functional implantation of a solubilized beta-adrenergic receptor in the membrane of a cell.

When the beta-adrenergic receptor of turkey erythrocytes was solubilized by deoxycholate, it retained its potential to activate an adenylate cyclase system. Electron microscopy showed that true solubilization had apparently been achieved; no residual membrane or vesicle structure was found. After removal of deoxycholate and addition of phospholipid, the reprecipitated beta-adrenergic receptor was implanted in the cell membrane of Friend erythroleukemia cells by using a chemical fusion method recently developed. Membranes prepared from the cells demonstrated 30-fold stimulation of the Friend cell adenylate cyclase by the implanted beta-adrenergic receptor. The function of the indigenous prostaglandin E(1) receptor of the Friend cells was not much affected by the implantation of large amounts of the foreign receptor. Activity mediated by the beta-adrenergic receptor reached 60% of the activity obtained with fluoride. The implanted receptor is therefore considered to be efficiently coupled to the adenylate cyclase system. The major difficulties hitherto preventing solubilization of hormone receptors and subsequent reconstitution of their function have been overcome by the approach developed in the present work. Conditions of solubilization need preserve only the receptor because all other components, even those unidentified as yet, can be supplied in excess by the adenylate cyclase system of the cell in which the receptor will be implanted. Subsequent recoupling of the receptor to the adenylate cyclase is performed in the native insoluble state of these molecules. Thus, the components need not be subjected to the hazards of solubilization in a common detergent as is usually required in reconstitution procedures. The importance of using implantation as an assay for a functional receptor in the course of purification and the likelihood that the procedure can be adapted to other receptors for hormones and neurotransmitters are discussed.

Adenylyl Cyclases↗