A microscopic study of Fc gamma RIII-mediated respiratory burst in neutrophils.

We investigated the relationship between the respiratory burst in neutrophils and the membrane distribution of the IgG receptor, Fc gamma RIII. Fc gamma RIII receptors were labeled with a fluoresceinated antibody that does not block binding of immune complexes. The respiratory burst was detected using covalently bound rosamine stain previously described for flow cytometric applications.

[Protein kinase C and its role in normal and transformed cells].

Data are reviewed on protein kinase C (PK-C) and its function in phosphorylation and regulation of different cellular proteins--enzymes, receptors, contractile and cytoskeletal proteins, as well as expression of cellular oncogenes. Besides, interactions between PK-C and cAMP-dependent PK are discussed. The evidence provided suggests that PK-C-phosphorylation may be one of the mechanisms of transformation of extracellular transmembrane signals (hormones, neuromediators, growth factors) into responsive biochemical cell reactions.

[Correlation between the proliferative activity and protein kinase C activities in ethidium bromide-sensitive and -resistant cells].

The protein kinase C (PK C) activity was determined in the cytosolic and membrane fractions of L- and CHO-K1-cells, both sensitive and resistant to ethidium bromide (EB). In the resistant cells (Lebr-25 and Cebr) a decreased enzyme activity was found in addition to alteration of the enzyme elution profile in the membrane preparations purified by DE-52 cellulose column chromatography. Methyltestosterone treated cells had a decreased enzyme activity in nonpurified membrane preparations in Lebr-25 cells, whereas the enzyme quantity in purified preparations remained the same.

[Cholesterol and phospholipid content of cells sensitive and resistant to ethidium bromide and its alteration in resistant cells as affected by methyltestosterone].

The content of cholesterol (Chl) and phospholipids (Phl) in cell lines L and CHO-K1, sensitive and resistant to the toxic action of ethidium bromide, has been studied. EB-resistant cells were shown to have lower amounts of Chl and Phl, and the ratio Chl/Phl in these cells was decreased too. EB-resistant cells, grown in serum-free medium, have dramatically decreased contents of Chl, while compared with the cells growing with serum.

[cAMP-dependent protein phosphorylation and its regulatory role in the cell].

Literary data are reviewed on the role of the cAMP-dependent phosphorylation of proteins in the regulation of cell metabolism, membrane permeability, and muscle contraction. It is suggested that a low cAMP level in the tumor and other actively proliferating cells may be associated with a raised exit of cAMP from cells into the surrounding medium because of the increased phosphorylation of the membrane proteins of these cells.

[Cyclic adenosine monophosphate content and its regulatory characteristics in Chinese hamster cells with genetically determined changes in the cell surface].

The intra- and extracellular concentrations of cyclic adenosine monophosphate (cAMP) in cell line CHO-K1, sensitive (clone 773) and resistant to cytotoxic action of ethidium bromide (EBr), colchicine (Cr) and actinomycin D (ADr), as well as the amount of cAMP in response to isoproterenol, 10% serum and ethidium bromide (EB) in these cells were studied. The increased level of cAMP in EBr- and, Cr-cells, and the decreased one--in ADr cells was found as compared with sensitive cells. The amount of cAMP extruded in the surrounding medium was lower for EBr- and Cr-cells and higher for ADr-cells, in comparison with sensitive cells.

[Effect of the tumor promotor 12-o-tetradecanoyl phorbol-13--acetate on cyclic adenosine monophosphate levels in cell cultures. Relation to cell proliferation].

A considerable increase in the level of cyclic adenosine monophosphate (cAMP) was found in hepatoma cultures (clones G-10, G-1c) and L-cells (clones Lebr 625, Lebr f. s.) in 30, 60 and 120 minutes after their treatment with the tumor promoter 12-o-tetradecanoyl-phorbol-13-acetate (TPA).

[Cyclic adenosine monophosphate and the enzyme activity of its metabolism in L cells sensitive and resistant to the cytotoxic action of ethidium bromide].

Using L-cells both sensitive and resistant to cytotoxic action of ethidium bromide (EB), a study was made of the intracellular level of cAMP, activities of adenylcyclase, phosphodiesterase and cAMP, liberated from cells into the surrounding medium. In EB resistant L-cells compared to EB sensitive ones, the higher level of cAMP with a decreased activity of adenylcyclase and an increased activity of the phosphodiesterase was shown to be associated with an impeded exit of cAMP from cells. It is suggested that the differences in cAMP levels in the EB sensitive and resistant cells are associated with the properties of cAMP-dependent protein kinases of these cells.

[Control of cell multiplication in vitro. II. Relationship between cell multiplication and cyclic AMP concentration].

Compairing non-transformed mouse fibroblasts and some L-cell variants, it was shown that the decrease of dependence on serum mitogenic factors, and the decease of sensitivity to the contact inhibition of growth do not always correlate with the decrease of intracellular cAMP content. The decrease of sensitivity of transformed cells to the factors limiting non-transformed cell growth in vivo might be also connected with a relative independence of the cell growth on the intracellular level of a cAMP.

[Effect of 0.005M CaCl-2 and 0.14M NaCl on the yield and extractibility of histones from rat liver nuclei].

The release and extraction of histones from the nuclei of rat liver under the influence of 0.005 M CaCl2 and 0.14 M NaCl was investigated.

[Corticosteroid hormones and histones (on the mechanism of action of hormones)].

The role of interaction between corticosteroid hormones and histones is considered with regard to hormonal activation of genes and some secondary changes of cells functional condition due to the presence of the hormones.