1,720,965 research outputs found
Modulation of the free sphingosine levels in Epstein Barr virus transformed human B lymphocites by phorbol dibutyrate
No full textThe amounts of free sphingosine in Epstein Barr virus transformed B lymphocytes (EBV-B) treated with sphingosine and phorbol-12,13-dibutyrate (PD) has been quantified by high performance liquid chromatography (HPLC). PD treatment did not affect intracellular sphingosine level, while it seems to lessen the removal of this long chain base in sphingosine-treated EBV-B cells. The previous results relative to sphingosine-dependent changes in choline-metabolite levels have to be interpreted on the basis of these results
P-31 and H-1 studies of ethanolamine-linked phosphoglycerides metabolism in human T Lymphocites
No full textAbstract: Aqueous and organic extracts of peripheral human T Iymphocytes and of T lymphoblastoid cell lines have been examinated by P-31 and H-1 NMR spectroscopy in order to study the metabolism of ethanolamine (Etn) linked phosphoglycerides. The results show that the Etn concentration in the culture medium determines the composition of Etn-containing metabolites and phospholipids. The effect of phorbol esters, stimulating the synthesis and the breakdown of choline-containing phospholipids has been also studied. A phorbol 12-myristate 13-acetate (PMA) dependent membrane phosphatidylethanolamine hydrolysis, presumably mediated by protein kinase C activity, has been demonstrated
Biochemical and biophysical effects of dexamethasone on human lymphoblastoid cell lines, studied by phosphorus-31 and proton NMR spectroscopy and fluorimetry
No full textRecently, it was reported that, in several cell lines, dexamethasone, a synthetic glucocorticoid, modulates the sphingolipid metab. and the intracellular sphingosine levels. It was suggested that its effects could be mediated by the prodn. of sphingosine from membrane sphingomyelin. The present study examd. the effect of dexamethasone on Epstein-Barr virus transformed B lymphocytes on lipid compn. and metab. In particular sphingosine levels by 31P and 1H NMR spectroscopy, high performance liq. chromatog. and dexamethasone effects on membrane structure by fluorimetry were investigated. Furthermore, dexamethasone effects on cellular proliferation and IgM secretion were evaluated
Trypanosoma lewisi in liquid culture: findings and comparisons with different types of media. Culture medium for Trypanosoma lewisi.
No full textThe culture technique used proved to be more simple and economical than the different culture methods described in literature. This process permits the in vitro growth of parasites for a period long enough (10 days) to determine the possible activity of drugs. On the 10th day the cultures are infectious
Trypanosoma lewisi: study of the activity of lonidamine in vitro and in vivo in rats
No full textA 0.35 mM concn. of lonidamine produced a 60% inhibition of the replication of T. lewisi in culture. Administered to Fischer rats infected with T. lewisi, lonidamine provoked a 30% decrease in the no. of parasites in the blood on the 5th day of infection. Electron microscopy studies (showing damage to the mitochondrial membrane) and the analyses of phosphorylated metabolites by 31P-NMR spectroscopy (decrease of nucleotide triphosphate and nucleotide dephosphate levels) suggested the presumed interference of lonidamine in the energy metab. of trypanosomes. The presence of 2-amino-3-phosphonopropionic acid and 2-aminoethylphosphonic acid phosphonates in T. lewisi trypomastigotes were also revealed by means of 31P-NMR
Cerebral metabolic compartmentation as revealed by <sup>13</sup>C NMR analysis of [1-<sup>13</sup>C]glucose metabolism
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dexamethasone-dependent modulation of cholesterol levels in human lymphoblastoid B cell line through sphingosine production
No full textThe effect of dexamethasone on lipid composition of Epstein-Barr virus transformed human B lymphocytes have been investigated by 31P- and 1H-NMR spectroscopy and compared to the effects due to exogenous sphingosine treatment. Furthermore, the effects of dexamethasone and sphingosine on membrane structure was evaluated by fluorimetry. No significant changes were evidenced in phospholipid composition and in the ratio of unsaturated to total fatty-acid chains. A significant increase in total cholesterol levels was evident at 30 min incubation with dexamethasone or sphingosine; a parallel increase in DPH polarization at 30 min was also demonstrated. TMA-DPH intensity measurements suggest a slowing of vesicular intracellular traffic due to the treatment. The results suggest a dexamethasone- and sphingosine-dependent inhibition of intracellular cholesterol transport
Effect of long-term feeding with acetyl-L-carnitine on the age-related changes in rat brain lipid composition: a study by <SUP>31</SUP>P NMR spectroscopy
No full textChanges in brain lipid composition have been determined in 24 months-old Fischer rats with respect to 6 months-old ones. The cerebral levels of sphingomyelin and cholesterol were found to be significantly increased in aged rats, whereas the amount of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, and phosphatidic acid appear to be unaffected by aging. Long-term feeding with acetyl-L-carnitine was able to reduce the age-dependent increase of both sphingomyelin and cholesterol cerebral levels with no effect on the other measured phospholipids. These findings shown that changes in membrane lipid metabolism and/or composition represent one of the alterations occurring in rat brain with aging, and that long-term feeding with acetyl-l-carnitine can be useful in normalizing these age-dependent disturbances
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