Biomedical subjects

M Rieber

Publications and source records attributed to M Rieber.

At least 55 records · Page 3Linked to original sources

PubMed1986

Novel DNA-protein complex and a large DNA in SLE cryoprecipitates.

Agarose gel electrophoresis of cryoprecipitates from systemic lupus erythematosus (SLE) patients revealed the presence of a slowly migrating DNAse I-sensitive DNA species at the top of the gel. Upon deproteinization, electrophoretic migration was modified favouring the migration of a 17.5 kb DNA fragment. Mixing experiments adding human serum or plasma to a lambda phage DNA digest revealed a DNA-protein interaction shown by an accumulation of high mol. wt polynucleotide at the top of the gels, and a slowed migration of the DNA bands. No comparable effect was observed when serum albumin was added to the lambda DNA digest. Dot hybridization analysis showed preferential reactivity of the 17.5 kb DNA to human DNA, implying its human origin. Our data suggests that most of this high molecular weight DNA exists as a DNA-2 protein complex. Our mixing experiments also suggest the occurrence of an excess of free DNA antibodies. We propose that the DNA-protein association may play a role in the stabilization and immunogenicity of the nucleoprotein complex.

Antigen-Antibody Complex↗

PubMed1985

Improved detection of labile cell-surface components with zinc chloride-aprotinin: demonstration of glycoprotein differences in K-1735 metastatic melanoma variants.

Metabolic labelling of K-1735 melanoma variants with 3H-glucosamine and cell harvesting with the commonly used protease inhibitor phenylmethylsulfonylfluoride revealed a Triton-insoluble fibronection-like 230 kd component in poorly metastatic cells. This component was not evident in highly metastatic cells. Significantly improved surface labelling and detection of the 230 kd glycoprotein in the highly metastatic variant was achieved by zinc chloride-aprotinin treatment of cells prior to harvesting. This procedure also revealed an increase in a trypsin-sensitive glycoprotein of higher molecular weight in the Triton-insoluble fraction of the highly metastatic cell variant. Glycoprotein labelling in this fraction showed an electrophoretic pattern strongly resembling that reported by others for the high-molecular-weight human melanoma-associated glycoprotein complex. The differential detection of the high-molecular-weight glycoprotein species in melanoma variants with differing metastatic abilities in an animal model provides a means of studying their possible relevance to metastatic melanoma. Our data also suggest that zinc chloride-aprotinin can be used to improve the detection of labile cell-surface components.

Animals↗

PubMed1985

Serum mediated changes in cell attachment and cytoplasmic organization of B16 melanoma correlates with selective alterations in secreted proteins.

B16 melanoma cells exhibited decreased adhesion to substration and the presence of cytoplasmic granules, resembling lipid inclusions, when cultured in vitro in the presence of syngenic serum from C57/BL6 mice. This constrasted with the rapid cell attachment and absence of cytoplasmic granules in cultures seeded in medium supplemented with an identical concentration of fetal bovine serum. Electrophoretic comparison of intracellular proteins revealed similar patterns in detergent-soluble and matrix-associated proteins from cells grown with bovine or mouse serum. However, a similar analysis of the conditioned media showed clear differences in methionine-rich species which migrated in the 100 kd region in cells grown with bovine serum, and as 110 kd component in cells grown with mouse serum. Our data indicate that the poor attachment to substratum and changes in cytoplasmic organization of B16 melanoma cells, is primarily associated with specific changes in secreted proteins.

Animals↗

PubMed1984

Relationship of a novel extracellular matrix glycoprotein to cell detachment in highly metastatic B16 melanoma: modulating effect of bromodeoxyuridine.

Growth of highly invasive B16 melanoma BL6 cells with bromodeoxyuridine (BUdR) decreases in vitro cell detachment and modulates extrapulmonary growth in vivo. We now show: (1) The presence of an 80 kd glycoprotein in the Triton-insoluble matrix of control BL6 cells but not in the corresponding fractions from BUdR-treated BL6 cells and poorly metastatic F1r cells. (2) The matrix fractions from the two last mentioned cells reveal Triton-insoluble glycoproteins of about 55-58 kd. (3) Mild trypsin treatment of intact cells before matrix preparation leads to the preferential disappearance of the 80 kd component from control BL6 matrix, suggesting its extracellular localization. (4) Prevention of Triton-mediated BL6 matrix detachment by zinc chloride pretreatment, and analysis of different BL6 clones with significant metastatic behavior, also revealed the presence of 80-90 kd matrix-associated glycoproteins in control but not in corresponding BUdR-grown cultures. Since BUdR decreases cell detachment, extrapulmonary metastasis and the levels of the 80-90 kd Triton-insoluble glycoprotein species in metastatic B16 melanoma, and this matrix component is also decreased in poorly metastatic F1r cells, we propose an involvement of this glycoconjugate in tumor cell detachment and metastatic behavior.

Animals↗

PubMed1984

Unequal forms of 140-110 kD glycoproteins in B16 melanoma cells with differing detachment properties and metastatic behavior: influence of bromodeoxyuridine.

Growth of B16 melanoma metastatic variants with 2.5 micrograms/ml of bromodeoxyuridine (BrdU) decreases cell detachment from the substratum, as measured by resistance to release by trypsin-EDTA treatment. Using an antiserum to intact melanoma cells and metabolic labelling of melanoma metastatic variants with 3H-glucosamine and subsequent electrophoretic analysis, we are now able to show that: (1) differential solubilization and immune precipitation permit the identification of hydrophilic glycoproteins of about 140 kD and 110 kD in melanoma cells with low colonizing ability; (2) the effects of BrdU on B16 melanoma appear to be exerted differentially on cells with differing metastatic behavior, since only poorly invasive melanoma cells show a stimulating effect of BrdU on the expression of the hydrophilic 140 kD glycoproteins; (3) cells with increased lung colonizing ability reveal hydrophobic 140 and 110 kD glycoprotein species with increased susceptibility to mild protease treatment, as compared with the corresponding components from poorly invasive cells. The possible relationship of the 140-110 kD glycoproteins to B16 melanoma biological behavior and cell-substratum interactions is suggested by the fact that such components undergo significant changes in cells with differing invasive behavior and detachment properties.

Animals↗

PubMed1984

Antibodies to laminin in American cutaneous leishmaniasis.

We found that serum samples from patients with different clinical forms of American cutaneous leishmaniasis (ACL) contained immunoglobulin G and immunoglobulin M antibodies which reacted with laminin but not with various other purified connective tissue components, such as collagen types I, III, IV, and V and fibronectin. Eighty-one percent of ACL patients had high antilaminin antibody levels, with a relationship existing between ACL ulcers and antibody levels. This was not, however, the case with patients having treated and healed ACL ulcers; only 34% of these patients had elevated antilaminin antibodies. Eighty-four percent of chronic Chagas' disease patients were also found to contain antilaminin antibodies that were limited to the immunoglobulin G class, but these were not detected in patients suffering from any of 11 other infectious diseases.

Adolescent↗

PubMed1983

Epidermal growth factor promoted changes in the triton-insoluble cytoskeletal matrix from human epidermal carcinoma cells: effect of bromodeoxyuridine.

We have used monolayers of bromodeoxyuridine (BrdU)-grown and control human epidermoid carcinoma (A431) cells to investigate the polypeptide changes resulting when cells are rounded by epidermal growth factor (EGF). Whereas no significant change was detected in Triton-soluble components, the urea-solubilized matrix fraction revealed greater levels of a 20 kd species in cells exposed to EGF, compared with the same cells not exposed to the growth factor. The corresponding urea fraction from BrdU-grown cells showed decreased levels of the 20 kd species as a result of exposure to EGF. Further evidence for a differential effect of EGF resulting from growth of the cells with the pyrimidine analog was observed in the matrix fraction soluble in SDS, which revealed a decrease in a 20 kd species resulting from exposure of control cells to EGF, with no comparable effect in BrdU-grown cells. Our results suggest that EGF induces a change in the properties of matrix-associated components of low molecular weight in an effect which appears to be modified by prior growth of cells with BrdU.

Bromodeoxyuridine↗

PubMed1983

Tumor-associated changes in plasma samples revealed by two-dimensional macromolecular mapping and selective lectin binding.

Two-dimensional electrophoretic analysis of plasma samples from EL-4 lymphoma-bearing C57 black mice revealed five 75 kd protein species in contrast with the presence of only two comparable components of similar migration in plasma from control animals. In contrast, no comparable alterations were observed in a comparison of plasma samples from L1210 tumor-bearing DBA mice and the corresponding plasma from animals immune-suppressed with antilymphocytic serum or in control plasma from DBA control plasma from DBA control animals. Analysis of selective binding using iodinated lectins revealed significant binding of I125 Lens culinaris in the more cathodic 75 kd component present in the plasma from control C57 black mice and a decreased Lens culinaris binding in the corresponding plasma components from EL-4 tumor-bearing C57 black animals. An identical assay with the same samples using I125 Ricinus communis did not show significant interaction with any 75 kd protein species, revealing instead lectin binding in components with molecular weights of about 70 and 50 kd. Our results suggest the use of combined two-dimensional electrophoretic separation and relative lectin binding in the analysis of tumor-specific and tumor-associated changes in plasma samples from tumor-bearing individuals.

Animals↗

PubMed1982