Oxalate toxicity in renal cells
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Viability assay
Lysophosphatidylcholine
The biomolecular mechanisms that mediate signal transduction by type II (gamma) interferon (IFN) are poorly understood. IFN-gamma is a potent growth inhibitory cytokine also endowed with antiviral, immunomodulatory, and differentiating activities on various cell targets, including neural cells. IFN-gamma induced a rapid and transient activation of phospholipase A2 in LAN-5, a human neuroblastoma cell line. A consequence of phospholipase A2 activation was the release of arachidonic acid and the generation of lysophospholipids from membrane phospholipids. Treatment of pre-labeled LAN-5 cells with a receptor-saturating concentration of IFN-gamma led to a time-dependent release of [3H]arachidonic acid into the culture media and generation of [32P]lysophosphatidylcholine. Pretreatment of cultures with the phospholipase A2 inhibitor, bromophenacyl bromide, markedly inhibited both [3H]arachidonic acid release and lysophosphatidylcholine production induced by IFN-gamma treatment. Pretreatment of LAN-5 cells with nordihydroguaiaretic acid, a lipoxygenase inhibitor, or with indomethacin, a cyclooxygenase inhibitor, amplified the release of [3H]arachidonic acid and production of lysophosphatidylcholine induced by non-saturating concentrations of IFN-gamma. In parallel, and with the same time-dependent effect, a significant decrease in phosphatidylcholine labeling was observed in IFN-gamma-treated cells, further indicating that a potential signal transduction mechanism of IFN-gamma is the hydrolysis of membrane phosphatidylcholine by phospholipase A2.
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Lysophosphatidylcholine
Lipid peroxide
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Lysophosphatidylcholine
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To determine if lysophosphatidylcholine (lysoPC) is able to induce proinflammatory changes in monocytes, its ability to stimulate arachidonic acid (AA) release, a product of phospholipase A2 (PLA 2 ) activity, has been analyzed. LysoPC increased AA release in THP‐1 and Mono Mac6 cells in a time‐ and concentration‐dependent manner. The monocytes expressed both secretory and cytosolic PLA 2 enzymes and AA release was strongly reduced by cellular pretreatment with different PLA 2 inhibitors and by pertussis toxin, an inhibitor of G i ‐protein activation. This indicates that both cytosolic and secretory PLA 2 enzymes regulate specific lysoPC receptor‐induced AA release, suggesting lysoPC participation in monocyte proinflammatory activation.
Lysophosphatidylcholine
Proinflammatory cytokine
Phospholipase A
Monocyte
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Objective To investigate the effect of oxalate urine on calcium oxalate crystallizations and free radicals in rat kidneyMethods The male Sprague-Dawiey rats were randomly divided into 4 groups,ie,0.5%,0.75%,1%ethylene glycol group and control group.0,2,4,6 weeklater,the rats were sacrificed and the urine oxalate concentration,the 24 hours urine oxalate excretion,the calcium oxalate crystallization in kidney,the renal free radical level were detectedResults With the urine oxalate concentration increasing,MDA was increased and SOD was reduced.At the end the calcium oxalate crystallization in rat kidney was increased obviously Conclusion The urine oxalate can induce the renal free radical creation excessively.The calcium oxalate crystallization formation in rat kidney has a significant relationship with the renal free radical level increasing
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Significant increases in lysophosphatidylcholine from a basal level of 4.2 +/- 0.36 nmol/mg of platelet protein to 6.4 +/- 0.46 nmol/mg of protein occur within 20 s after the addition of thrombin (5 units/ml) to washed human platelets. The increases are essentially complete by 1 min, at which time levels of 8.5 +/- 0.53 nmol of lysophosphatidylcholine/mg of platelet protein are reached. Decreases in phosphatidylcholine and also phosphatidylethanolamine occur within 20 s after stimulation of platelets by thrombin. These changes were detected by quantitative measurements of endogenous phospholipid phosphorus after extraction and thin layer chromatography of the platelet lipids. The concomitant increases in lysophosphatidylcholine and decreases in phosphatidylcholine, as well as the decreases in phosphatidylethanolamine, can only be explained by the stimulation of phospholipase A2 activity in platelets by thrombin.
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Liberation
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Lysophosphatidylcholine
Brain ischemia
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Abstract Activation of macrophages and macrophage cell lines by bacterial LPS elicits a delayed phase of PG biosynthesis that appears to be entirely mediated by cyclooxygenase-2 (COX-2). In previous work, we found that a catalytically active group V secreted phospholipase A2 (sPLA2-V) was required for COX-2 induction, but the nature of the sPLA2-V metabolite involved was not defined. In this study, we identify lysophosphatidylcholine (lysoPC) as the sPLA2-V downstream mediator involved in COX-2 induction by LPS-stimulated macrophages. Inhibition of sPLA2-V by RNA interference or by the cell-permeable compound scalaradial blocked LPS-induced COX-2 expression, and this inhibition was overcome by incubating the cells with a nonhydrolyzable lysoPC analog, but not by arachidonic acid or oleic acid. Moreover, inhibition of sPLA2-V by scalaradial also prevented the activation of the transcription factor c-Rel, and such an inhibition was also selectively overcome by the lysoPC analog. Collectively, these results support a model whereby sPLA2-V hydrolysis of phospholipids upon LPS stimulation results in lysoPC generation, which in turn regulates COX-2 expression by a mechanism involving the transcriptional activity of c-Rel.
Lysophosphatidylcholine
Phospholipase A
Lysophospholipase
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Lysophosphatidylcholine, arachidonic acid and docosahexaenoic acid were found to have a concentration‐dependent inhibitory effect on the motility of human sperm, whilst phosphatidylcholine had no effect. Seminal plasma attenuated the sperm‐immobilizing potencies of these lipids. Because all of the three inhibitors of motility are hydrolytic products of phosphatidylcholine, and the catalytic enzyme, phospholipase A 2 , is known to be calcium dependent, it is suggested that calcium might inhibit sperm motility by activating phospholipase A 2 which in turn releases lysophosphatidylcholine and free fatty acids.
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Lysophosphatidylcholine (lysoPC) is a polar lipid formed in cells and tissues under normal conditions and is known to cause tissue damage in a variety of experimental systems. We have therefore examined the possibility that increased amounts of lysoPC are formed in activated inflammatory cells and are involved in their tissue-damaging action. Human neutrophil leucocytes were labelled with [14C]arachidonic acid (AA), activated with the calcium ionophore A23187, and the degradation of phospholipids, with subsequent release of AA and AA metabolites, was studied. We also studied neutrophil metabolism of [14C]lysoPC in the presence of different concentrations of cold lysoPC, and the relation between phospholipid degradation and release of N-acetyl-β-gluco-saminidase (nAG), a lysosomal enzyme. We found that the release of both AA and nAG was coupled to a degradation of phosphatidylcholine (PC), and that the neutrophils were able to metabolise lower, but not higher, concentrations of lysoPC. Moreover, the phospholipase A2 inhibitor, nordihydroguaiaretic acid significantly inhibited PC degradation, lysoPC formation, and nAG release, whereas the lipoxygenase inhibitor, BW 755C had little effect on these parameters. These findings demonstrate that the AA mobilization in activated neutrophils is associated with PC degradation, and point to be possibility that the ensuing lysoPC formation might mediate lysosomal enzyme release.
Lysophosphatidylcholine
Nordihydroguaiaretic acid
Phosphatidylethanolamine
Phospholipase A
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