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Biomedical subjects

L B Margolis

Publications and source records attributed to L B Margolis.

At least 73 records · Page 4Linked to original sources
PubMed1979

Upper surfaces of epithelial sheets and of fluid lipid films are nonadhesive for platelets.

Platelet-rich rabbit plasma was incubated with surfaces of two different types--sheets of cultured mouse kidney epithelium and films of different lipids. The upper surface of epithelial sheets was found to be nonadhesive for platelets; in the same cultures, the platelets attached easily to the glass surface not covered by epithelial cells. Platelets did not attach to the surface of lipids (egg lecthin and dioleoyllecithin) that were in the liquid-crystalline state at 23 degrees C. In contrast, the surface of the films made of lipids (dipalmitoyl- and distearoyllecithin) that were in the crystalline state at 23 degrees C was adhesive for platelets. It had been found previously that the surfaces of epithelial sheets and of liquid lipid films are nonadhesive for fibroblasts. Possible mechanisms responsible for the nonadhesiveness of these surfaces are discussed. It is stressed that the factors responsible for nonadhesiveness of epithelial surfaces may be similar to those responsible for nonadhesiveness of the luminal surface of endothelium in blood vessels.

Animals↗
PubMed1977

[Preparation of liposomes possessing immunologic specificity].

The authors obtained artificial lipid vesicles--liposomes containing immunoglobulins. IgG in the complexes with liposomes proved to retain their immunological activity: the liposomes containing rabbit anti-mouse IgG agglutinated in the presence of donkey anti-rabbit IgG or mouse serum. As shown by the use of liposomes containing H3-inulin and immunoglobulins against the cell surface determinants, these immuno-liposomes selectively bound the target, but not the control cells. Specific binding with the antigenic cell surface determinants was also demonstrated in the case of liposomes bearing the nonimmune globulins besides the immunoglobulins. By the indirect immunofluorescence method it was shown that the nonimmune globulins in complex with the immune liposomes were selectively bound by target cells. A possible use of the immuno-liposomes to deliver various substances selectively to the cells of particular types, and to incorporate new antigens into the cell membrane is discussed.

Animals↗
PubMed1977

[Effect of colchicine on polarization of cells on narrow strips of an adherent substrate].

Effect of antitubulin colcemide on polarization of mouse fibroblast-like cells on anisotropic substrate was studied. Such a substrate was obtained by scratching narrow strips in lipid films, adsorbed on the glass. The control cells were seen spread only along the strips, and in 4-6 hours they approached the length of120-150 mcm. In colcemide-containing media, the cells remain in an unspread state for a long time; they extrude their outgrowths both along the strip and perpendicularly to it. Due to frequent refractions of outgrowths, two thirds of colcemide-treated cells were detached from the substrate. Possible mechanisms of these effects of antitubulins are discussed.

Animals↗
PubMed1975

Quantitative evaluation of cell orientation in culture.

A quantitative method to assess mutual orientation of cells in cultures on a substrate includes the following operations: (1) the cellular groups to be evaluated are chosen; (2) position of the long axis for each nucleus of the group is determined; (3) the axis OX is arbitrary chosen for every group and the angles alphai between the long axis of every nucleus i and the axis OX are measured. Every nucleus i corresponds to a vector of unit length ei with the angles 2alpha. D, the mean of the vectors ei for every cell group is calculated. This value of D is compared with a set of values of D computed according to a model of mutual orientation studies in a simulation experiment. In this model the group of n vectors consists of a fraction of Kn parallel vectors (o less than or equal to K less than or equal to I) and of (I minus K)n randomly oriented vectors. K corresponding to the computed D which is equal to the experimental value of D is considered as an index of orientation for the group. Contact orientation with respect to the relief of the substrate may be evaluated as a root mean square deviation sigma0 to the angles between the long axes of cell nuclei and the direction of relief. Examples of the measurements of K and sigma0 in cell cultures are given.

Animals↗
PubMed1975

[A method of measuring cell orientation].

A method is described for measuring cell nuclei orientation in culture. The nuclear orientation in the experiment was compared with that obtained in the model experiment with electronic computer. The method developed allows to compare nuclear orientation in parts of culture which differ both by area and number of nuclei. The method can be modified for measuring cell nuclei orientation with reference to the substrate relief. Examples are given of the method's application for comparing orientation of mouse embryonic fibroblasts and cells of the strain L.

Animals↗
PubMed1974

Orientation of mitosis of fibroblasts is determined in the interphase.

Time-lapse films of the cultures of mouse L fibroblasts have been analyzed to find out the angles between the direction of the big axis of interphase nucleus before mitosis and the direction of the mitotic furrow in the same cell. In 41 out of 51 mitoses this angle has been found to be more than 60 degrees . Thus, the orientation of mitotic furrows depends on the internal polarity of the cell before mitosis.

Animals↗
PubMed1973

Contact inhibition of movement in the cultures of transformed cells.

Results of cell-cell collisions were studied with the aid of time-lapse microcinematography in primary cultures of normal mouse-embryo fibroblast-like cells and in cultures of transformed mouse cells of two types: (a) primary fibroblast-like cells transformed by Moloney mouse sarcoma virus; (b) neoplastic fibroblasts of the CIM strain. Collisions of normal fibroblast-like cells and CIM cells in mixed cultures were also analyzed. Classification of the results of collisions was based on observation of the movements of the active cell edge during the first hour after the moment when this edge had contacted another cell. Three types of collision results were detected: halt of the active edge, overlapping, and underlapping. The relative number of overlappings was not higher and that of halts not lower in the cultures of transformed cells as compared with those of normal cells. Analysis of the collisions of normal fibroblasts with transformed cells gave similar results. Thus, the altered morphology of the cultures of these transformed cells cannot be explained by loss of contact inhibition of movement leading to increased ability of cells to move over the surfaces of other cells after collision.

Animals↗
PubMed1972

Defective formation of the lamellar cytoplasm by neoplastic fibroblasts (L cells-transformed cells-cell attachment-contact inhibition-scanning electron microscopy-microcinematography).

Isolated cultures of mouse L-cells are similar to those of normal cells in showing contact inhibition of movement and topoinhibition of growth. In mixed cultures with untransformed mouse embryo fibroblasts, their parent strain, however, L cells are able to form colonies above the monolayer of normal fibroblasts, i.e., they have a property characteristic of transformed cells. Analysis of microcinematographic data suggests that the behavior of L cells in mixed cultures is a result of their defective attachment to the substratum. Scanning electron microscopy showed that attachment of a normal fibroblast was accompanied by the formation of a wide ring of flattened cytoplasm spread on the substratum (lamellar cytoplasm). This structure was observed to disintegrate in newly attached L cells. The structure of the lamellar cytoplasm remained abnormal in the fully spread L cells. The mean area of lamellar cytoplasm was 3- to 4-times less in L cells than in normal fibroblasts. It is suggested that deficient formation of lamellar cytoplasm may be the basis of the inability of L cells to interact normally with embryo fibroblasts.

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