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Biomedical subjects

R Laskov

Publications and source records attributed to R Laskov.

At least 55 records · Page 3Linked to original sources
PubMed1979

Two spontaneous BALB/c lymphomas synthesize IgM: monomers and half molecules are isolated and characterized whereas another molecule resembles IgD.

Spontaneous lymphomas of BALB/c mice, both in vivo tumors and cell lines established in long term tissue cultures, were investigated for their ability to synthesize IgM by using radiolabeled amino acid precursors. Immunoglobulins manufactured by lymphomas K46 and L10A had the m.w. of monomeric IgM and IgM half molecule. Both of these molecules could be immunoprecipitated with class-specific anti-IgM but not anti-IgA or anti-IgG. When precipitated with polyvalent anti-Ig L10A synthesized monomeric immunoglobulins that migrated as two peaks in contrast to their single counterpart precipitated with anti-IgM. The second peak migrated in the region expected for IgD. Monomer and half molecules were composed of similar ratios of mu-chains to light chains linked by disulfide bonds. The mu2L2 monomer of these B cell lines migrated slightly slower in SDS PAGE than a mu2L2 secreted by a myeloma. Thus, these lymphomas synthesize immunoglobulins with the chemical and antigenic characteristics typical of monomeric membrane-attached IgM and IgM half molecules, plus a molecule resembling IgD on L10A only. Lymphoma assembly of monomeric IgM may follow the same initial biosynthetic sequence as myeloma assembly.

Animals↗
PubMed1978

Characteristic surface morphology of human and murine myeloma cells: a scanning and transmission electron microscopic study.

Cells from cultured human and murine myeloma cell lines and circulating leukaemic plasma cells from four patients with generalized myeloma were studied by transmission and scanning electron microscopy and time-lapse cinematography. Both circulating and cultured cells exhibited consistent surface architectures and varying numbers of prominent blebs of different sizes were seen, in addition to microvilli. The presence of surface blebs appears to be a characteristic feature for secreting and non-secreting myeloma cells.

Animals↗
PubMed1978

Myeloma cells: surface morphology as seen by scanning and transmission electron microscopy.

Cells from cultured murine myeloma cell lines and circulating leukemic plasma cells from two patients with generalized myeloma were studied by transmission and scanning electron microscopy. Both circulating and cultured cells exhibited consistent surface architectures. Microvilli and varying numbers of prominent blebs of different sizes were seen. The presence of surface blebs is a characteristic feature of secreting and nonsecreting myeloma cells.

Animals↗
PubMed1975

Characterization of cytoplasmic DNA of mouse-myeloma cells.

Cytoplasmic DNA from mouse myeloma cells comprised between 1% and 2% of the total cellular DNA. Detergent-prepared cytoplasmic lysate consisted mainly of 8-S and 22-S species. While these DNA species were present in the 13000 times g pellet of the detergent-prepared cytoplasmic lysate, only the light DNA species was present in the 13000 times g supernatant fraction. In neutral CsCl gradients the DNA of both cytoplasmic fractions had a buoyant density of 1700 g/cm3, which is identical to that of nuclear DNA. The similarity between the cytoplasmic and nuclear DNA was also demonstrated by analysis on alkaline CsCl gradients. A small proportion of closed-circular DNA, presumably of mitochondrial origin, was demonstrated only in cytoplasmic fraction obtained from mechanically disrupted cells and not in detergent-prepared cytoplasmic lysate. It was found that poly (A)-containing mRNA and 28-S ribosomal RNA hybridized to about the same extent to the cytoplasmic DNA as compared to nuclear DNA. The results indicate that most of the cytoplasmic DNA in myeloma cells is similar to nuclear DNA and does not consist of mitochondrial DNA.

Animals↗
PubMed1975

Immune precipitation of immunoglobulin producing polysomes from mouse myeloma cells.

MPC-11 myeloma cells synthesizing IgG were labeled in vitro with 3H-uridine and the cell lysates, or purified polysomes treated with rabbit antiserum against the purified MPC-11 protein. The specificity of the immune precipitation was tested by rabbit anti-egg albumin and by precipitation of polysomes from "non-producer" myeloma and HeLa cells. The specific precipitation was 10 to 15% of the total cytoplasmic RNA for the IgG-producing clone of MPC-11 and about 2% for the non-producer clone or HeLa cells. Up to 20% of the total polysomal and ribosomal RNA were precipitated from the IgG producing clone. This value correlated with the IgG synthesis of these cells which is also about 20% of the total protein produced. The results suggest that myeloma cells produce a relatively large quantity of IgG due to the presence of a large amount of specific m-RNA molecules.

Animals↗
PubMed1974

Independent synthesis of light and heavy chains: quantitation of light-chain production by mouse myeloma variants.

The rates of immunoglobulin synthesis have been examined in two MFC-11 cell lines which were independently adapted to tissue culture and in light-chain-producing variants derived from each of them. One cell line synthesized 2.5 pg immunoglobulin/cell/h, while the other synthesized 3.6 pg immunoglobulin/cell/h. The ratio of heavy and light chains in the two cell lines was approximately the same, and the size of the intracellular pool of immunoglobulin was proportioned to the rate of synthesis. Variants which had spontaneously lost the ability to produce heavy chains continued to synthesize light chains at approximately the same rate as their parent cell line.

Animals↗