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At least 1,027 records · Page 57Linked to original sources
PubMed1999

Oxidized low density lipoproteins induce apoptosis in PHA-activated peripheral blood mononuclear cells and in the Jurkat T-cell line.

Oxidized low density lipoproteins (oxLDLs) and activated T lymphocytes are present in early atherosclerotic plaques. It has been shown that oxLDLs are cytotoxic to cultured vascular cells but their possible toxic action on T lymphocytes has not been described. Peripheral blood lymphocytes from healthy individuals were stimulated in vitro with the polyclonal activator phytohemagglutinin and treated with various doses of native and mildly oxidized LDLs. Low doses of oxLDLs inhibited cell growth and DNA synthesis after 48 h culture and at 200 microg apoB/ml we observed a loss of cell viability. Dead cells did not exhibit significant increase of alteration of membrane integrity (i.e., necrosis) but showed chromatin fragmentation evaluated by DNA staining with 4', 6-diamidino-2-phenylindole and propidium iodide. This fragmentation increased with TBARS and hydroperoxide levels. The expression of early apoptosis marker Apo2.7 rose among the CD3(+) T-cell population. In addition, morphological analysis showed apoptotic features (cell shrinking, nucleus condensation, and fragmentation). Study of phosphatidylserine expression using Annexin V confirmed that oxLDLs induced apoptosis in activated lymphocytes. In the Jurkat T-cell line cultured with oxLDLs, apoptotic morphological changes (condensation and nucleus fragmentation) were observed and they were accompanied by DNA fragmentation visualized by propidium iodide staining and electrophoresis showing apoptotic ladder. These results demonstrate that mildly oxidized LDLs induce apoptosis in a part of activated and proliferating T cells. T-lymphocyte apoptosis induction in atherosclerotic lesions might contribute to the development of an inappropriate local T cell response.

Apoptosis↗
PubMed1999

[Detection of K-ras mutations in colon cancer by PHA-PHFA (preferential homoduplex formation assay)].

The mutations of K-ras gene have been demonstrated at frequencies of about 40% in human colorectal cancer. We applied a developed PCR-preferential homoduplex formation assay (PCR-PHFA) to detect a point mutation of K-ras gene in the surgical specimens from thirty patients with colorectal cancer. This method is based on the strand competition during hybridization between a double labeled amplicon, prepared from biotin and DNP labeled primers, and an unlabeled amplicon. The procedure of this method is simple and speedy, and suitable to detect mutations in a small number of samples. By using this method, the mutations were found in 37% (11/30) and confirmed by sequencing analysis. The results suggest that the PCR-PHFA system may be useful for detecting low frequent mutation of K-ras gene even in the case of an early cancer.

Colorectal Neoplasms↗
PubMed1975

Induction of PHA response in mouse bone marrow cells by thymic extracts as studied by changes in the structuredness of cytoplasmic matrix.

The specificity and cross-species activity of thymic extracts and some non-specific agents on some alleged properties of T cells and their precursors in the bone marrow cells of normal, nude and thymectomized mice was studied in vitro. The phenomenon of changes in the structuredness of cytoplasmic matrix (SCM) was used to assess the maturation and responses of cells treated with the extracts to mitogens, i.e. phytohaemagglutinin and concanavalin A. We found that thymic extracts of calf and mouse origin induce functional 'maturation' which can be abrogated by cycloheximide, an inhibitor of protein synthesis. The nonspecific agents used (spleen extracts, PPD, dBcAMP and endotoxin) had no effect on bone marrow cells, as measured by changes in the SCM. The method of measuring SCM using the technique of fluorescence polarization is described.

Animals↗
PubMed1975

Migration inhibition of peritoneal cells and PHA lymphocyte toxicity in rats during methylcholanthrene carcinogenesis.

Peritoneal exudate cells obtained from rats bearing primary methylcholanthrene-induced tumors were shown to be inhibited in their capillary tube migration capacity as compared to cells from nontreated control litter-mates. The survival of rat peripheral blood lymphocytes harvested from the same individuals were tested simultaneously in short-term cultures with a standard concentration of Phytohemagglutinin. Lymphocytes from tumor-bearing rats survived better than control lymphocytes in 24-hour cultures with Phytohemagglutinin. A correlation was found from a comparison of the results of these two methods. These findings are discussed with regard to the possibility of T cells depletion from peripheral lymphocyte population, together with the enrichment of this population with B cells in tumor-bearing individuals.

Animals↗
PubMed1975

Field application to malaria studies of the passive haemagglutination (PHA) test with lyophilized cells.

Lyophilized cells for the passive (formerly indirect) haemagglutination test for malaria were tested in a small field trial. A comparison was made with results obtained with samples from the same persons by another method in another laboratory (Center for Disease Control, Atlanta, GA, USA). The use of lyophilized cells of standardized reactivity clearly adds to the simplicity and rapidity of the test, and justifies its recommendation for use in field studies.

Freeze Drying↗
PubMed2000

Modulation of LPS-, PHA- and M. tuberculosis-mediated cytokine production by pentoxifylline and thalidomide.

Pentoxifylline and thalidomide have been used to downregulate the production of TNF-alpha in several disease entities including mycobacterial infections and autoimmune disorders. These drugs inhibit the production of TNF-alpha by different mechanisms, but little is known about possible synergism and modulation of other cytokines. Pentoxifylline and thalidomide inhibited the in vitro stimulated production of TNF-alpha, IL-1 beta and IFN-gamma in blood mononuclear cells. No significant modulation of antiinflammatory cytokines was found. When used together, these agents demonstrated additive inhibition, but no synergism. Modulation of cytokine response was similar when different stimuli were used, including M. tuberculosis in tuberculin-positive individuals. Therefore, the balance between efficacy and toxicity may be more favourable when pentoxifylline and thalidomide are used together instead of either drug alone. Clinical studies are needed to establish this advantage when anti-cytokine strategies are considered.

Cells, Cultured↗