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K Burdzy

Publications and source records attributed to K Burdzy.

5 recordsLinked to original sources
PubMed1992

Competition between cell-substratum interactions and cell-cell interactions.

Clusterin, a glycoprotein which elicits the aggregation of a wide variety of cells (Fritz, I. B., and Burdy, K.:J. Cell Physiol., 140:18-28, 1989), has been utilized to investigate some of the factors modulating the competition between cell-substratum interactions and cell-cell interactions. We compared the responses to clusterin by anchorage-independent cells (erythrocytes) with those by anchorage-dependent TM4 cells (a cell line derived from neonatal mouse testis cells). Cells were maintained in culture in the presence of various substrata chosen to enhance cell-substratum interactions (laminin-coated wells), or to diminish cell-substratum interactions (agarose-coated wells). Results obtained showed that the aggregation of erythrocytes elicited by clusterin was independent of the nature of the substratum. In contrast, clusterin addition resulted in aggregation of anchorage-dependent TM4 cells only when TM4 cell-substratum interactions were weak. Thus, clusterin did not aggregate TM4 cells plated upon a laminin substratum, but readily aggregated TM4 cells plated upon an agarose-coated substratum, independent of the sequence of addition of cells and clusterin to the culture dish. We utilized YIGSR, a peptide which competes with laminin for laminin receptors, to determine the possible role of laminin receptors on TM4 cells in the competition between cell-substratum interactions and cell-cell interactions. The presence of YIGSR did not alter responses of erythrocytes to clusterin under all conditions examined. In contrast, the responses of TM4 cells to clusterin were greatly changed. YIGSR addition resulted in the inhibition of aggregation of TM4 cells otherwise elicited by clusterin. YIGSR also prevented attachment of TM4 cells to a laminin-coated surface, but this was reversed by the presence of clusterin. We discuss the possible roles of clusterin and laminin in altering the balance in the competition between cell to cell interactions and cell to substratum interactions.

Animals↗
PubMed1991

Clustering of erythrocytes by fibrinogen is inhibited by carnitine: evidence that sulfhydryl groups on red blood cell membranes are involved in carnitine actions.

Carnitine is bound by intact red blood cells, by red blood cell ghosts, and by glutaraldehyde-fixed human erythrocytes in a non-saturable, temperature-dependent manner. Binding of carnitine by these preparations is blocked by sulfhydryl reagents. Incubation or preincubation of red blood cell preparations with carnitine inhibits the aggregation of erythrocytes otherwise elicited by fibrinogen. Identical effects are obtained with red blood cell ghosts. In contrast, choline, even at high concentrations, is inactive in preventing the aggregation of erythrocytes. We discuss possible mechanisms by which carnitine favors the dispersion of red blood cells, and we present data indicating that sulfhydryl groups on erythrocyte membranes are required to permit these carnitine actions to be manifested.

Carnitine↗
PubMed1991

High-resolution scanning electron micrographs of freeze-cracked cells in testes from normal and irradiated rats at different stages of gonadal development.

Newly developed techniques in high-resolution scanning electron microscopy (SEM) and for tissue-processing procedures have been applied to an investigation of structures of various cells in rat testes at different stages of gonadal maturation. A series of high-resolution SEM micrographs are presented which survey the surfaces of different types of testis cells during normal development, and which also illustrate ultrastructural features of some of their intracellular organelles. In addition, a series of high-resolution SEM micrographs are presented which compare the structural features of Sertoli cells in normal testes with those in germ-cell-depleted testes obtained from rats killed at varying times after having been irradiated in utero. We describe our observations on the structural properties of surfaces and intracellular organelles in Sertoli cells, Leydig cells, peritubular myoid cells, and some classes of germinal cells. We also consider the possible role of Sertoli cell apical cytoplasmic processes in lumen formation. Similarities are pointed out between the structure of germ-cell-depleted testes, resulting from irradiation in utero, and the structure of germ-cell-depleted testes in seasonal breeders during periods of involution. Finally, we discuss advantages and disadvantages of methods employed to reveal the fine structure of intracellular organelles in cells of the testis.

Animals↗
PubMed1989

Novel action of carnitine: inhibition of aggregation of dispersed cells elicited by clusterin in vitro.

A novel effect of carnitine and O-acylcarnitine derivatives has been described. The presence of these compounds has been shown to inhibit the aggregation of erythrocytes otherwise elicited by the addition of clusterin or fetuin. The specificity of carnitine action has been investigated by comparing influences of chemically related compounds. The concentrations required for inhibition by approximately 50% of aggregation of erythrocytes by clusterin under in vitro conditions defined were determined to be 1.5 mM for L(-) or D(+) enantiomers of carnitine; 0.5 mM for decanoyl(-)- or (+)-carnitine; 0.13 mM for lauroyl(-)- or (+)-carnitine, and 0.05 mM for myristoyl(-)- or (+)-carnitine. In contrast, concentrations up to 12.5 mM of dimethylcarnitine, deoxycarnitine, acetylcholine, acetyl-beta-methylcholine, or inositol had no detectable inhibitory effect on aggregation elicited by clusterin. Clusterin addition also resulted in the aggregation of three other cell types examined (guinea pig spermatozoa, a cell line derived from testes of neonatal mice called TM4 cells, and Sertoli cells from testes of 20 day-old rats). As in the case with erythrocytes, the presence of carnitine inhibited aggregation of spermatozoa, TM4 cells, and Sertoli cells in suspension. We consider possible mechanisms by which carnitine inhibits aggregation of erythrocytes and other populations of dispersed cells incubated in the presence of clusterin.

Animals↗