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Biomedical subjects

B Westermark

Publications and source records attributed to B Westermark.

At least 217 records · Page 12Linked to original sources
PubMed1980

Chemical and biological properties of a growth factor from human-cultured osteosarcoma cells: resemblance with platelet-derived growth factor.

A human osteosarcoma cell line, U-2 OS, cultured under serum-free conditions, was shown to produce a growth factor (osteosarcoma-derived growth factor, ODGF) for human-cultured glial cells, fibroblasts, and other cells. ODGF, collected from the spent medium of 2 OS cultures, was purified by a sequence involving heparin-Sepharose chromatography, hydrophobic chromatography, gel chromatography, and preparative gel electrophresis in SDS. Purified ODGF, at a concentration of 3 ng/ml, elicited a mitogenic response in human glial cells equivalent to 50% of that afforded by human serum at a final concentration of 1%. The preparation was estimated to be > 50% pure. The biological activity of ODGF resided in a cationic, relatively heat-resistant, reduction-susceptible protein with a molecular weight of 30,000 (by gel chromatography and SDS-gel electrophoresis). The electrophoretic behaviour of radioiodinated ODGF suggested that the protein was composed of two different polypeptide chains (about 13,000-14,00 and 16,000-17,000 daltons, respectively) linked via disulphide bonds. The molecular makeup of ODGF was thus similar to that of platelet-derived growth factor. 125I-ODGF could be precipitated by an antibody to platelet-derived growth factor, indicating that the two factors were immunologically related. Resemblance with platelet-derived growth factor was also indicated by the finding that the latter (but not, e.g., fibroblast growth factor or epidermal growth factor) competed with 125I-ODGF for binding to human-cultured glial cells.

Blood Platelets↗
PubMed1980

Antitumor activity of L-2,4 diaminobuturic acid against mouse fibrosarcoma cells in vitro and in vivo.

Mouse fibrosarcoma cells were grown in vitro and incubated with L-2,4 diaminobuturic acid, a non-metabolizable amino acid. The tumor cells were irreversibly and totally damaged by incubation with 10 mM DAB for 24 h at 37 degrees C. The cell-destructive effect by DAB was probably due to an osmotic lysis induced by the non-saturated intracellular accumulation of DAB. The harmful effect of DAB could be abolished by concomitant incubation with L-alanine and L-methionine, that compete with DAB for the same transport system, while the D-forms of the same amino acids as well as sarcosine had a weak effect. The fibrosarcoma cells were also transplanted s.c. into mice that were subsequently treated with i.p. injections of an isotonic 0.1 M DAB solution. The neoplastic cells were transplanted into totally 90 animals. The mean tumor weight of 42 treated animals was 1.16 g (+/- 0.77 g) compared with the corresponding figures of the 27 untreated mice, that were 2.05 g (+/- 1.22 g), i.e., a 43.4% reduction of tumor growth. There were, however, 17 drug-related deaths. Treatment with DAB generally resulted in weight reduction, at least partly due to loss of appetite, in animals. In addition, neurological symptoms of a specific character could develop among several of the treated animals. The side effects apparently restrict the usefulness of DAB alone as an anti-tumor agent, but since the principle of action of DAB is unique and not shared by other known chemotherapeutics it might offer new possibilities in the combined treatment of neoplastic growth.

Aminobutyrates↗
PubMed1980

Ageing of human glial cells in culture: increase in the fraction of non-dividers as demonstrated by a minicloning technique.

A minicloning technique was used to analyse quantitatively the fraction of cells incapable of division in mass populations of human glial cells at various passage levels. The percentage of non-dividers rose from 18 to 73% between passages 11 and 40 at which further subcultivation of the mass culture became impossible. The non-dividers were predominantly arrested in G1; only a minor fraction of G2 arrested cells was established. Although not conclusive, the data suggest that commitment to irreversible loss of division potential increases as a function of the number of completed cell cycles which a glial cell has completed.

Cell Cycle↗
PubMed1980

Stimulation of fibroblast migration by epidermal growth factor.

Epidermal growth factor has been found to stimulate the migration of human foreskin fibroblasts grown at low serum concentration. This effect may be caused by a direct activation of the cytoskeletal elements or indirectly via an increased production of migration facilitating matrix proteins. We speculate on the possible implications of the present finding in the invasive properties of growth factor releasing transformed cells and in the direction of migration of cells in embryonal development.

Blood↗
PubMed1980

Growth of normal human glial cells in a defined medium containing platelet-derived growth factor.

DNA synthesis and cell division were measured in serum-free cultures of human normal diploid glial cells maintained in MCDB 105 medium. In growth factor-free cultures the cells remained viable but the cell number was essentially constant. Supplementation with 10 ng of epidermal growth factor or platelet-derived growth factor per ml significantly stimulated DNA synthesis and cell multiplication. Growth occurred both when cells were allowed to settle in serum-containing medium and when cells were plated in serum-free medium. In the latter type of cultures, the cell yield was improved bu incubating the cells in collagen-coated dishes. The use of a miniclone technique allowed the analysis of cell multiplication induced by platelet-derived growth factor at the clonal level and demonstrated that the growth factor induced several cell cycle rounds in a large fraction of clones. The results show that normal cells grown in a recently developed synthetic medium (MCDB 105) supplemented with pure growth factors may multiply without the addition of plasma-derived factors ("progression factors"). It is suggested that the need fo progression factors may simply depend on the composition of the synthetic nutrient medium.

Blood↗
PubMed1980

An established human cell line derived from a malignant mediastinal teratoma.

An established cell line derived from a human malignant mediastinal teratoma is described. The cell line was composed of slightly atypical fibroblast cells with a population-doubling time of 24 h at the exponential growth phase. The reason why the emerging cell line became fibroblastic although other tissues were present in the original tumor may be that fibroblasts so readily grow in culture. Chromosome banding showed a hypertriploid stemline number, S = 78. Almost all of the analysed karyotypes had seven markers in common. Eleven other markers, occurring at low frequency, were also detected. The origin of all markers except one could be deduced.

Adult↗
PubMed1980

Transmission and scanning electron microscopy of whole glioma cells cultured in vitro.

Twenty-six lines of malignant glioma cells have been established in our laboratories. The cell lines have all been derived from low-differentiated human astrocytomas which did not differ in their histopathological classification. A representative selection of these lines was cultured on formvar-covered, carbon stabilized, gold, EM grids. After glutaraldehyde and osmium fixation, they were dehydrated, critical-point dried and studied as whole-cell preparations in the transmission electron microscopy (TEM) mode. The specimens were then coated with 10-nm of a gold/palladium alloy and the same cells identified and examined in the scanning electron microscopy (SEM) mode. This combined TEM and SEM method makes it possible to relate intracellular structures to surface details, such as ruffles, endocytotic vacuoles, filopodia and microvilli. The study also revealed a large spectrum of dissimilarities between the studied lines, which underlines the fact that no essential structural features of a tumor type can be drawn from studies on occasional lines of cells derived from it.

Astrocytoma↗
PubMed1979

Desensitisation of cultured glial cells to epidermal growth factor by receptor down-regulation.

Epidermal growth factor (EGF), which can be purified from the mouse submaxillary gland or from pregnant human urine, is a potent multiplication-stimulating factor for several types of cultured cells, including human fibroblasts and glial cells. The molecule binds with high affinity and saturation kinetics to a cell-surface receptor, is subsequently internalised and finally degraded. The binding event is accompanied by a reduction in the number of EGF receptors. This phenomenon--'receptor down-regulation'--has been demonstrated with several hormones and may be a general principle for the modulation of binding groups on the outer cell surface. Further, it has been proposed that receptor loss acts to regulate the cellular response to the binding ligand. The present study provides direct experimental support for this hypothesis. It demonstrates that down-regulation of EGF receptors on glial cells causes desensitisation of the mitogenic response of these cells to subsequent stimulation with EGF.

Cell Line↗
PubMed1979

Glial fibrillary acidic protein and intermediate filaments in human glioma cells.

Cultured human glioma cells were studied by double indirect immunofluorescence technique using antisera against intermediate filaments and glial fibrillary acidic protein. With both antisera cytoplasmic fibrillar fluorescence was seen. Perinuclear bundles of intermediate-sized filaments, induced by vinblastine treatment, were strongly stained with both antisera. The degree of codistribution of the two types of antigenic determinants varied considerably from cell to cell. The results suggest that two types of filament-related antigenic determinants can be present in the same cell, and also that glial fibrillary acidic protein-related filaments may possess functional similarities to the intermediate filaments found in other cells. Glial fibrillary acidic protein remains as a useful and specific antigenic marker for the study of glial cells in vitro.

Astrocytoma↗
PubMed1979

A comparative study of glycosaminoglycans in cultures of human, normal and malignant glial cells.

The glycosaminoglycans (GAG) of human cultured normal glial and malignant glioma cell lines were studied using 35S-sulphate or 3H-glucosamine as markers. 35S-labelled GAG were assayed by precipitation with cetylpyridinium chloride; 3H-labelled sulphated GAG and 3H-labelled hyaluronic acid were quantitated after separation on a DEAE-cellulos column. The net production of GAG and the distribution, composition and turnover of GAG were similar in all of the normal cell lines tested, but showed a great variability in the malignant cell lines. Most of the glioma cell lines produced more hyaluronic acid and less sulphated GAG than the normal cell lines, but exceptions were noted. The GAG of the trypsin susceptible (pericellular pool of normal glial cells consisted mainly of heparan sulphate with only minor amounts of other GAG. The analogous material of most glioma cells showed hyaluronic acid as the major GAG. Material liberated by trypsin from EDTA-detached cells (membrane fraction) was enriched in heparan sulphate as compared to the entire pericellular pool. Substrate attached material (SAM) left with the plastic dish after EDTA treatment of normal cultures was rich in heparan sulphate, whereas SAM of glioma cells lacked heparan sulphate or showed greatly reduced amounts of this component. Release of newly synthesized GAG to the extracellular medium was a rapid process in the normal cells but was more or less delayed in the glioma cells. The extracellular medium of the malignant glioma cultures was consistently poor in dermatan sulphate, as compared to that of normal cultures.

Cell Adhesion↗
PubMed1979

Protein-coated agarose surfaces for attachment of cells.

Plastic dishes were coated with an agarose layer. The layer was modified by covalently binding proteins to it, using the CNBr-method. Cells were seeded on the dishes and the number of attached cells was evaluated. The specificity of the attachment was demonstrated by showing that cells, carrying specific membrane-bound immunoglobulins, attached only to the corresponding anti-immunoglobulins. This indicated that the method could be used for cell sorting. The attachment of cells to proteins was influenced by the amount of bound protein, incubation time, temperature and the degree of trypsinization. Most attached cells were viable for several days and when dying they detached. Detailed morphological and cytochemical analyses of the dynamics of attachment and cytoplasmic spreading on the chemically well-defined surfaces were possible using the new method.

Burkitt Lymphoma↗
PubMed1979

Tetrodotoxin-sensitive sodium channels in normal human fibroblasts and normal human glia-like cells.

Tetrodotoxin-sensitive sodium channels are detectable in normal human fibroblasts and in "glia-like" cells at appreciable levels when compared to what is observed in established neuronal cell lines in culture. Two- to 3-fold stimulations of sodium influx are observed in the presence of 0.2 mM veratridine and scorpion venom at 0.1 mg/ml. Tetrodotoxin (2 microM) inhibits the observed stimulation of sodium influx. Previous work has indicated that these neurotoxins act on the voltage-sensitive sodium ionophore of excitable cells, and the presence of such channels in cells generally considered nonexcitable raises questions regarding both the uniqueness of this ionophore as a property of excitable cells and the origin of the cells generally described as fibroblasts.

Cell Line↗
PubMed1979

Thyrotropin is not a growth factor for human thyroid cells in culture.

Thyroid cells, obtained from both normal human tissue and benign nodular goiter, were cultured and maintained in vitro in 4-18 passages. Cultures with confluent cells accumulated cyclic AMP (10-150 times the basal amount) upon addition of bovine thyrotropin (100 milliunits/ml), indicating that the cells in culture maintained a thyrotropin-sensitive adenylate cyclase system. Addition of high doses of thyrotropin also induced a characteristic and reversible change in the morphology of the cells. The effect of thyrotropin on cell growth was studied in short- and long-term experiments. Thyrotropin reduced [(3)H]thymidine incorporation in a dose-dependent fashion in all cultures of thyroid cells. The maximal inhibition over a 24-hr period was about 50%. The thyroid cells were notably sensitive, and the half-maximal effect occurred at about 100 milliunits of thyrotropin per ml. In contrast, the hormone had no effect on [(3)H]-thymidine incorporation into human glial cells. Low doses of thyrotropin also had no effect on human fibroblasts and, at high doses, a stimulation of [(3)H]thymidine incorporation was seen. Thyroid cell cultures grown in the presence of 10 milliunits of thyrotropin per ml for 7-14 days had a slower growth rate and 24-36% lower cell numbers at saturation density than control dishes, indicating that the hormone also had a long-term effect on cell proliferation. The data agree with in vitro studies by others of the effects of corticotropin and lutropin on target cells and suggest that in vivo the primary action of pituitary trophic hormones on endocrine tissues is not stimulation of growth.

Cell Division↗
PubMed1979

Platelet-derived growth factor: purification and partial characterization.

A cationic protein that stimulates DNA synthesis in human cultured cells was isolated from human platelets by ion exchange chromatography, hydrophobic chromatography, gel chromatography, and gel electrophoresis in sodium dodecyl sulfate. The electrophoretic behavior of biologically active or radioiodinated and reduced growth factor indicated that the native protein (approximately 30,000 daltons) was composed of two different polypeptides (approximately 13,000-14,000 and 16,000-17,000 daltons, respectively) linked via reduction-susceptible bonds. The stimulatory activity on human glial cells of the purified product at a concentration of approximately 4 ng/ml (0.13 nM) was equal to that of 1% human serum.

Blood Platelets↗
PubMed1979

Ultrastructural features of cultured human glia and glioma cells.

The fine structure of three lines of human normal glial cells and eight established lines of malignant glioma cells are described. The glial cell lines were ultrastructurally very similar whereas the glioma cell lines differed greatly from one another. In sparse proliferating cultures there were no consistent findings which distinguished the glioma cell lines as a group from the normal glial cells. Only in post-confluent cultures could the consistently irregular cell surfaces and ruffling, both at the cell periphery and centrally on the upper cell surface, with associated pinocytosis, distinguish the glioma from the post-confluent glial cultures, which did not possess these properties. The common attributes of post-confluent glioma cells reflect the cells' continued proliferation. The glioma lines did display individual ultrastructural characteristics which appear to be stable, the glioma lines having retained these during a number of years of continual passage.

Cell Division↗
PubMed1979

The fine structure of growing human glia and glioma cells. Whole cell preparations.

Three lines of normal human glia cells and eight established lines of malignant glioma cells have been studied in the electron microscope (E.M.), using preparations of critical-point dried whole cells, sparsely grown on formvar-coated, E. M., gold grids. The malignant cell lines showed a very varied morphology, almost every line having its peculiarities as compared to the essentially identical normal glia lines. The major differences noted concerned the form of the leading lamellae, number of microspikes and the distribution of organelles such as secondary lysosomes and mitochondria. No single consistent finding made it possible to differentiate the glioma cells as a group from the glia cells in sparse cultures. The findings of this study show some of the individual glioma cell lines to have characteristic cell-surface structures. They were found to be identical with the findings in previous SEM studies, suggesting the peculiarities of the individual malignant glioma lines to be stable and retained, despite continual passage.

Cell Division↗
PubMed1979

Growth stimulation of aged cells in culture.

Human glial cultures of any passage consist of two populations of cells: those with mitotic ability, and the non-dividers. The fraction of non-dividers increases with age of the culture, and dominates in late passages. When cells from midphase II cultures (passage 28) were sparsely seeded in dishes containing agarose partially covered by small, isolated, palladium squares (haptotactic islands) they settled on the palladium squares but not on the agarose. 58% of the cells divided, and formed mini-clones which became density growth inhibited within 10 days in medium with 5% serum. The non-dividers comprised 42%. They showed a characteristic indolent motility pattern. When these cultures were exposed to 15% fetal calf serum and 2 ng/ml mEGF (mouse epidermal growth factor) for another 5 days, nine per cent of the solitary cells had divided, and DNA measurements showed another 20% to have entered the S phase. About 40% of the initial single cells presented morphological alterations after the stimulation which are known to be early signs of entrance into the cell cycle after blockage in G1/G0. The present results in combination with earlier findings suggest that "old" cells approaching the non-dividing state become increasingly insensitive to stimulation by growth-promoting factors.

Cell Cycle↗