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Biomedical subjects

W Ostertag

Publications and source records attributed to W Ostertag.

At least 127 records · Page 7Linked to original sources
PubMed1980

Myeloproliferative virus, a cloned murine sarcoma virus with spleen focus-forming properties in adult mice.

Myeloproliferative virus, derived from Moloney sarcoma virus, causes erythroleukemia and myeloid leukemia in adult mice. This virus is also capable of fibroblast transformation in vitro. The virus consists of two separable biological entities which have been cloned. The helper virus component caused no visible changes in adult mice, whereas the defective virus induced both spleen focus formation and a large increase in erythroid precursor cells but retained the sarcoma virus property of transforming fibroblasts in vitro. Thus, myeloproliferative virus is the first murine sarcoma virus which induces erythroleukemia in adult animals.

Animals↗
PubMed1979

The Friend virus genome: partial characterization of a complete DNA copy.

A complementary DNA probe has been prepared from the Friend murine erythroleukaemia virus complex released by Friend cells (FV cDNAD-) and Friend cells induced to differentiate (FV cDNAD+). Molecular hybridization analysis shows that: (a) FV cDNAD+ is close to being a complete copy of the virus genome and the distribution of sequences is uniform with respect to their distribution in the Friend virus genome. (b) Hybridization of 70S RNA from the cloned helper virus to the total FVc DNAD+ probe demonstrates that a large proportion of the cDNA is specific to the transforming spleen focus forming virus. (c) Hybridization of the probe to normal and transformed cell DNA shows that there are about seven Friend virus related genes in normal DNA and almost twice this amount in transformed cell DNA. A significant minor proportion (20%) of the cDNA probe anneals only to virus related sequences in the transformed cell DNA. (d) An analysis of the kinetics of annealing of the cDNA to an excess template RNA shows that the minimum base sequence complexity of the Friend virus complex is 4 x 10(6). (e) An analysis of the cross hybridization between FV cDNAD+ and 60 to 70S RNA isolated from virus released by uninduced and induced cells shows that the genome of the induced and uninduced Friend virus is almost identical.

Animals↗
PubMed1978

Changes in genome composition of the Friend virus complex in erythroleukemia cells during the course of differentiation induced by dimethyl sulfoxide.

The Friend spleen focus-forming virus (SFFV) complex released by Friend virus-transformed erythroid cells has been analyzed with respect to changes in the genome composition that may occur during induction of erythropoiesis with dimethyl sulfoxide. It is shown that: (a) There are three types of virus particles, one with buoyant density 1.20 g/ml, one with density 1.17 g/ml (the density of the cloned lymphatic leukemia virus helper component of the complex), and a major fraction that has a density of 1.14 g/ml. (b) Three RNA subunits-35S, 32S, and 30S-have previously been shown to be detectable in the Friend virus complex. The 1.20-g/ml particles contain only 30S RNA, whilst the 1.14- to 1.17-g/ml particles contain a mixture consisting of predominantly 30S and 32S RNA and about 5-10% 35S RNA. (c) Induction of differentiation results in an increase in the 1.14-g/ml particles and 32S RNA. The amount of 30S RNA does not change. (d) Hybridization of the different genomic viral RNAs with full-length virus cDNA shows that the 30S RNA (of induced and uninduced Friend virus) is more closely related to the 32S RNA of the induced Friend virus than to the 32S RNA of the constitutively released Friend virus. (e) The 30S RNA contains SFFV-specific sequences. (f) A hypothesis is presented in which the induction of the new 32S RNA species is related to the increase of SFFV activity and to a specific function of the SFFV during induction of erythropoiesis.

Cell Differentiation↗
PubMed1977

Surface changes in differentiating Friend erythroleukemic cells in culture.

The sensitivity to agglutination by several plant lectins has been studied during the induced erythroid differentiation of Friend erythroleukemic cells in culture. In addition, the number of lectin receptors on the cell has been measured. It is shown that early during the differentiation, there is an increase in agglutinability while the receptor density remains constant. In the later phase of the differentiation process, the cells lose their sensitivity to agglutination while the receptor number and density increases. These changes were not observed on nonerythroid mastocytoma culture cells. Two nondifferentiating variants of the FL cells were shown to have altered sensitivities to agglutination by ConA.

Agglutination↗
PubMed1977

Interactions of rodent malarial parasites with Friend erythroleukemia cells in vitro.

The ability of Plasmodium chabaudi and P. yoelii to bind to Friend erythroleukemia cells in vitro was examined. Extensive binding of P. yoelii and weaker binding of P. chabaudi was observed. Binding to mouse fibroblasts was not seen, although there was some binding to cells of a mouse mastocytoma. The binding of P. yoelii to Friend cells was sensitive to specific antiserum. The development of P. berghei and P. yoelii in Friend cells was followed by microscopic examination and measurement of the infectivity of those cells in mice. Friend cells infected with both species appeared to develop morphologically normal intracellular forms of the parasites. P. yoelii-infected cells were infective in sensitive mice for 3 days after addition of the parasites, and this infectivity was not sensitive to treatment in vitro with mouse anti-P. yoelii serum.

Animals↗
PubMed1976

Analysis by computer-controlled cell sorter of Friend virus-transformed cells in different stages of differentiation.

In most systems involving cellular differentiation and cellular transformation the biological process is non-synchronous and the sample heterogeneous. In order to answer some of the basic questions about the control mechanisms of cellular changes and the order in which they proceed one must have access to homogeneous classes of cells. Friend virus transformed erythroid cells which are stably maintained in tissue culture can be chemically induced to differentiate and are thus very advantageous for in vitro studies (1-3). With such a system the questions which we pose are a) the reversibility of the differentiation process; b) the order of steps in the production of specialized messenger RNA; c) the time of shut-off of undifferentiated messenger production; d) the relationship of viral RNA production to the differentiation process; e) the onset and extent of specific protein synthesis; f) the correlation of DNA metabolism with the timing or course of events. By using a computer-controlled cell separator we can select live cells on the basis of their macromolecular content, membrane properties (using a new parameter, fluorescence emission anisotropy), and size (4, 5, 34). Thus with proper probes as described here, we are able to select cells at different stages in their differentiation and can begin to attack the questions posed above.

Cell Differentiation↗
PubMed1976

Dimethylsulfoxide-induced differentiation and hemoglobin synthesis in tissue cultures of rat erythroleukemia cells transformed by 7,12-dimethylbenz(a)anthracene.

Permanent cell lines from transplantable tumors from 7, 12-dimethylbenz(a)anthracene-induced erythroleukemia of the rat were established. These cell lines maintain their erythroid nature. Erythroid differentiation can be induced by dimethylsulfoxide. This is shown by decrease in cell size, appearance of red and benzidine positive cells, and induced synthesis of four out of six adult globin chains.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1976

Size, subunit composition, and secondary structure of the Friend virus genome.

Electron microscope and gel electrophoresis studies show that the high-molecular-weight (50 to 70S) RNA extract from Friend virus (FV) is a dimer with the same basic structure previously observed for the RNAs from RD-114 virus, baboon virus, and woolly monkey virus. This observation greatly strengthens the inference that the dimer structure is a general characteristic of the RNAs of all mammalian type C viruses. The FV dimer is slightly less stable than the RNA dimer of woolly monkey virus, which is, in turn, much less stable than those of RD-114 and baboon virus. There are three FV monomer components, small (S), medium (M), and large (L), with molecular lengths of 6.7 +/- 0.6, 7.7 +/- 0.6, and 9.5 +/- 0.6 kilobases, respectively. There are approximately equal amounts of the S and M components and much less of the L component. Most of the dimers are homodimers (SS, MM, and LL). The frequency of heterodimers (SM, SL, ML) is much less than expected for a random assortment model.

Friend murine leukemia virus↗
PubMed1976

Studies of cellular differentiation by automated cell separation. Two model systems: Friend virus-transformed cells and Hydra attenuata.

The automated high-speed analysis and separation of cells on the basis of spectroscopic parameters has been applied to studies of cellular differentiation in two systems. The temporal changes following induction of differentiation by dimethylsulfoxide in the Friend virus-transformed erythroid cells were quantitated by multiparameter analysis leading to the separation of discrete subpopulations. Thus, following induction, cell size decreased as measured by light scattering, the number of H-2 histocompatibility antigen sites decreased as measured by indirect fluorescent antibody binding, the number of lectin-binding sites per cell increased as measured by fluorescein-labeled concanavalin-A and the microviscosity of the hydrocarbon region of the plasma membrane increased as determined by the fluorescence emission anisotropy of the membrane probe 1,6-diphenyl-1,3,5-hexatriene. Cells were separated on the basis of several of these parameters and analyzed for their hemogloglobin content by benzidine staining. Examination of cells separated according to the anisotropy parameter showed that high anisotropy values were correlated with (a) small cell size, (b) positive staining with benzidine and (c) pronounced reactivity with fluorescent antibody to the erythrocyte protein spectrin. Disaggregated cells from Hydra attenuata were selectively stained with the dyes rhodanile blue, 7-(p-methoxybenzylamino)-4-nitrobenz-2-oxa-1,3-diazole and fluorescamine. Distribution analyses and preliminary separations indicated the feasibility of obtaining homogeneous classes of cell types in a viable state. The experiments with emission anisotropy represent the first analyses and separations of single cells on the basis of fluorescence polarization. Many other uses of this technique are anticipated.

Autoanalysis↗
PubMed1975

RNA-dependent DNA polymerase from a cell line derived from the bone marrow of a patient with polycythemia vera.

A RNA-dependent DNA polymerase was isolated from a human cell line derived from the bone marrow of a patient with polycythemia vera. The purification procedure included chromatography on phosphocellulose and oligo(dT)-cellulose, and glycerol gradient centrifugation. The enzyme could be distinguished from polymerase A by salt elution from phosphocellulose, utilization of poly(rC) - oligo(dG) and its molecular size of about 70000, as determined by centrifugation. Throughout the purification procedure ribonuclease H activity was co-purified. Upon dodecylsulfate-polyacrylamide electrophoresis on microgradient gels two main bands with molecular weights of 68000 and 66000 and three minor bands were detected. The enzyme preferentially used poly(rA) - oligo(dT) as template-primer compared with poly(dA) - oligo(dT). It incorporated dGMP into polymer on poly(rC) - oligo(dG).

Bone Marrow↗