Search PubMed⌕ Search

Biomedical subjects

J M Dayer

Publications and source records attributed to J M Dayer.

At least 235 records · Page 13Linked to original sources
PubMed1979

Localization of [3H]ouabain-sensitive Na+ pump sites in cultured pig kidney cells.

Pig kidney cells, LLC-PK1, grown by standard tissue-culture techniques form monolayers and maintain morphological features characteristic of epithelia. Cultures exposed to 2 X 10(-6) M [3H]ouabain for 30 min at 37 degrees C bound 7.77 +/- 0.37 pmol/mg protein. This could be reduced by 58% by incubation in the presence of 45 mM K+. Freeze-dry radioautographic localization of [3H]ouabain-binding sites revealed grains distributed only along that fraction of the plasmalemma directly facing the culture-dish surface. Binding and localization of [3H]ouabain were correlated with an inhibition of the Na+ pump in these cells because analysis of cellular electrolytes in control cultures versus those exposed to 10(-3) M ouabain revealed a fall in K+ from 419 +/- 9 to 173 +/- 4 mmol/kg dry wt with a reciprocal increase in Na+. There was no change in cell H2O. Similarly, oxygen consumption was reduced by 32% after exposure to ouabain. These results provide direct evidence that in epithelial cells in culture the membrane facing the culture dish corresponds to the basolateral membrane of epithelial cells in vivo.

Animals↗
PubMed1979

Participation of monocyte-macrophages and lymphocytes in the production of a factor that stimulates collagenase and prostaglandin release by rheumatoid synovial cells.

Cultured mononuclear cells from human peripheral blood produce a soluble factor (MCF) that stimulates collagenase and prostaglandin E2 (PGE2) release by cultured rheumatoid synovial cells up to several hundred fold. These target rheumatoid synovial cells lack conventional macrophage markers. To determine which mononuclear cells are the source of MCF, purified populations of monocyte-macrophages, thymus-derived (T) lymphocytes, and bone marrow-derived (B) lymphocytes were prepared. The monocyte-macrophages alone produced levels of MCF that were proportional to cell density but unaffected by phytohemagglutinin or pokeweed mitogen. No detectable collagenase activity was produced by the cultured monocyte-macrophages or lymphocytes. Purified T lymphocytes produced levels of MCF approximately or equal to 1--3% those of purified monocyte-macrophages in the presence or absence of the above lectins. Purified T lymphocytes modulated the production of MCF by the monocyte-macrophages, however, in a manner dependent upon relative cell densities and the presence of lectins. For example, at optimal ratios of T lymphocytes: monocyte-macrophages, MCF production was markedly stimulated by pokeweed mitogen. Thus, interactions of T lymphocytes and monocyte-macrophages could be important in determining levels of MCF, which regulate collagenase and PGE2 production by target synovial cells in inflammatory arthritis.

Arthritis, Rheumatoid↗
PubMed1979

Collagenase and prostaglandin in connective tissue destruction: cell-cell and humoral interactions.

Connective tissue destruction is a major characteristic of chornic rheumatoid arthritis (RA). This process is accompanied by local cellular and humoral inflammatory reactions. Long-term cultures of adherent synovial cells (ASC) from patients with RA produce large amounts of collagenase and prostaglandin (PGE2), two substances that play a role in the degradation of joint structures. Lvels of collagenase and PGE2 can be stimulated (up to several hundred-fold) with a soluble factor (MCF) from cultured peripheral blood mononuclear cells (MW approximately 14,000). The monocyte-macrophages alone produce MCF but can be stimulated directly with Fc fragments of immunoglobulin or concanavalin A to increase MCF production. Addition of T lymphocytes in the presence of lectin or antigen significantly enhances the production of MCF. MCF affects other biological processes in synovial cells such as the rate of collagen synthesis, cell proliferation and sensitivity to PGE2 as well as collagen itself can further modulate collagenase release by the synovial cells and function in an amplificative loop. The understanding of these interactions between cells, mediator-effector substances and connective tissue substrates may provide a basis for devising more rational approaches to therapy of the destructive lesions which characterize RA.

Arthritis, Rheumatoid↗
PubMed1979

Increased prostaglandin production by human monocytes after membrane receptor activation.

Human monocytes in culture release small amounts of prostaglandin E (PGE) into the medium. Addition of Fc fragments of IgG to human monocyte monolayer cultures results in a marked increase in PGE release; Fab fragments, monomeric IgG, and human serum albumin have no effect. An IgG1 myeloma has no effect on PGE levels but addition of the heat aggreagted protein results in a marked increase of PGE secretion. Exposure of the cells to Con A, which binds to a specific monocyte plasma membrane receptor, also results in a large increase in PGE release. The magnitude of the increase in PGE secretion produced by exposure of the monocytes to these ligands greatly exceeds the stimulation observed after the addition of antigen-activated mononuclear cell supernatants, zymosan, Sephadex beads, or endotoxin, to monocyte cultures. Prostaglandin E2 (PGE2) accounts for approximately 70% of the total prostaglandins released by stimulated cells. After addition of Indomethacin to monocyte cultures, the stimulatory effects of the ligands on PGE release are inhibited. Addition of Con A to monocyte cultures results in an increased incorporation of [3H]-arachidonic acid into PGE2. These results suggest that this ligand stimulates synthesis as well as release of this prostaglandin.

Binding Sites↗
PubMed1978

[Autoimmune hemolytic anemia induced by mefenamic acid].

A case of autoimmunohemolytic anemia following mefenamic acid therapy is described. A free anti-erythrocytic antibody of the IgG class was found in the serum of the patient. The same antibody was also found in the eluate of the patient's red cells. No blood group specificity could be demonstrated. Direct participation of the drug in the antibody red cell reaction could be ruled out by "facilitation" and "inhibition" tests.

Anemia, Hemolytic, Autoimmune↗
PubMed1978

Response to hormones of cells cultured from human giant cell tumors of bone.

Giant cell tumors of bone obtained from 7 patients were dispersed with clostridial collagenase and trypsin and adherent cells were maintained in culture. Early cultures contained both mononucleated and multinucleated cells presumably derived from the stromal and giant cells of the original tumor. The original multinucleated cells did not survive for greater than 7-10 days whereas the mononucleated cells persisted and could be passaged by trypsinization. In 5 of 7 early cultures exposed to parathyroid hormone (PTH) there was a rise in cAMP within 5-10 min in both cells and medium which averaged approximately 12-fold. None of the cells responded to calcitonin and a variable rise in cAMP was seen after incubation with prostaglandin E2. In cells cultured from 3 tumors the PTH response disappeared with passage of the cells, but in the remaining 2, PTH response persisted through multiple passages. The presence as well as the magnitude of the PTH-induced cAMP response in these cells is consistent with a skeletal origin.

Adult↗
PubMed1977

Prostaglandin production by rheumatoid synovial cells: stimulation by a factor from human mononuclear Cells.

Human peripheral blood mononuclear cells (lymphocyte-monocyte) in culture release a solube factor which can stimulate, up to 200-fold, production of prostaglandin E2 by isolated, adherent, rheumatoid synovial cells. Production of the factor by the mononuclear cells is enhanced by phytohemagglutinin. This factor is similar in apparent mol vt (10,000-20,000) to that which also stimulates collagenase production by the same cells.

Arthritis, Rheumatoid↗
PubMed1977

Collagenase production by rheumatoid synovial cells: stimulation by a human lymphocyte factor.

Human peripheral blood lymphocytes incubated in culture for 1 to 3 days at 37 degree C, but not at 4 degree C, release a soluble factor which can stimulate, up to 400-fold, collagenase production by isolated, adherent, rheumatoid synovial cells. Production of lymphocyte factor is enhanced by phytohemagglutinin or concanavalin A. By gel filtration the factor has an apparent molecular weight of about 12,000.

Arthritis, Rheumatoid↗
PubMed1976

Production of collagenase and prostaglandins by isolated adherent rheumatoid synovial cells.

We have studied cells dispersed with proteolytic enzymes from rheumatoid arthritic synovectomy specimens to determine the cell type(s) responsible for joint destruction. Initially 10-50% of these cells adhered to culture dishes within 24 hr and were of two main types: small, round cells and larger, stellate cells. During 1-4 days of culture, 5-25% had Fc receptors and 25-50% showed brisk phagocytosis. Daily producition, per 10(6) cells of collagenase (EC 3.4.24.3) (after trypsin pretreatment) was up to 70 mug of collagen fibrils lysed per min at 37 degrees (70 units), of prostaglandin (PGE2), up to about 1200 ng, and of lysozyme, up to about 100 mug. Under identical conditions of assay, fibroblasts grown from explants of synovium produced no detectable collagenase or lysozyme, and PGE2 was only 2-4 ng. With the dispersed cell preparations, macrophage markers (Fc receptors and lysozyme) were undetectable after 4 days and PGE2 decreased rapidly after about 7 more days. However, collagenase production continued for 3-25 weeks, and in some cultures, after cell passage. At these later stages, large, slow-growing stellate cells were predominant and could phagocytose carbon particles if incubated for greater than 6-8 hr. Indomethacin (14 muM) inhibited PGE2 but stimulated collagenase production whereas dexamethasone (10 nM) inhibited both. Production of PGE2 and collagenase in large amounts in vitro by these cells suggests that they may be involved in joint destruction in vivo. The precise origin of these synovial cells and the mechanisms responsible for the sustained production of collagenase at a high rate remain unidentified.

Arthritis, Rheumatoid↗
PubMed1976

Cephalothin-induced immune hemolytic anemia.

A patient with renal disease developed Coombs-positive hemolytic anemia while receiving cephalothin therapy. An anti-cephalothin IgG antibody was detected in the patient's serum and in the eluates from her erythrocytes. In addition, nonimmunologic binding of normal and patient's serum proteins to her own and cephalothin-coated normal red cells was demonstrated. Skin tests and in vitro lymphocyte stimulation revealed that the patient was sensitized to cephalothin and also to ampicillin. Careful investigation of drug-induced hemolytic anemias reveals the complexity of the immune mechanisms involved.

Anemia, Hemolytic↗
PubMedDate not supplied

Phorbol diester 12-O-tetradecanoylphorbol 13-acetate (TPA) up-regulates the expression of estrogen receptors in human THP-1 leukemia cells.

In the present work, we have inspected expression of estrogen receptors (ER) and their regulation by the phorbol diester 12-O-tetradecanoylphorbol 13-acetate (TPA) in a leukemic cell line, the THP-1 cells, using multiple experimental approaches. Firstly, ligand binding assay (LBA) revealed that control (unstimulated) THP-1 cells express type I (high affinity, limited capacity) ER in the nuclear fraction only, whilst treatment of cells with TPA resulted in the appearance of type I ER in the soluble fraction as well, with the 50 ng/ml dose and the 48 h incubation time being the most effective experimental condition. A concomitant increase of type II ER was also seen in both soluble and nuclear cell fractions. Unstimulated THP-1 cells were found to be ER negative by immunocytochemistry; conversely, cells exposed to 50 ng/ml TPA for 48 h stained positively for ER, with the majority of cells having a strong nuclear staining. Scrutiny of ER mRNA expression using reverse transcriptase-polymerase chain reaction showed the presence of a wild type ER transcript in both control and TPA-treated THP-1 cells, though levels of ER mRNA were found to be comparatively higher in the latter. This combined evidence would imply that the TPA-induced differentiation of THP-1 cells is accompanied by the rise of high affinity (type I) ER, suggesting that estrogens may play a role in the regulation of macrophage activity during the inflammatory and/or the immune response.

Cell Differentiation↗