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Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new micromethod for the determination of sphingomyelin in samples suspended in aqueous solutions, and modified micromethods for determining phosphatidylcholine and phosphatidylglycerol were used to determine phosphatidylcholine and sphingomyelin (detection limits of 1.8 mumol/l), and phosphatidylglycerol (detection limit of 2.3 mumol/l) in lipid dispersions, membranes from sheep erythrocytes and platelets, and pulmonary surfactants from rats of different ages and rats maintained under normobaric hyperoxia for 2 days prior to their sacrifice. The procedures are easy to perform, accurate, require less sample than conventional methods and can also be applied directly to aqueous samples. Phospholipase C and sphingomyelinase were used to release phosphorylcholine from phosphatidylglycerol and sphingomyelin, respectively. The choline released from phosphorylcholine by alkaline phosphatase is reconverted to phosphorylcholine by ATP and choline kinase. In the phophatidylglycerol determination, phospholipase D was used to release glycerol and phosphatidate. The glycerol formed was converted to glycerolphosphate using ATP and glycerol kinase. In all cases, the ADP thus formed was determined by following the enzymatic conversion of NADH to NAD at 340 nm in an coupled pyruvate kinase/lactate dehydrogenase system. Significant variations in the phospholipid composition of rat pulmonary surfactant were found during development; in particular there was an increase in the phosphatidylglycerol content of adult rats as compared with younger rats. Hyperoxia produced changes in the phosphatidylglycerol content of surfactant from adult rats, but not from 2-day old rats.
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PMID:Enzymatic determination of phosphatidylcholine, sphingomyelin and phosphatidylglycerol in lipid dispersions, blood cell membranes and rat pulmonary surfactant. 870 43

We investigated the effect of hyperoxia on phospholipase D (PLD) activation in bovine lung microvascular endothelial cells (BLMVECs). Generation of intracellular reactive oxygen species in BLMVECs exposed to hyperoxia for 2 or 24 h was three-fold higher compared with normoxic cells as measured by dichlorodihydrofluorescein di(acetoxymethyl ester) fluorescence. Exposure of BLMVECs to hyperoxia for 2 or 24 h attenuated 12-O-tetradecanoylphorbol 13-acetate (TPA)-mediated PLD activation compared with normoxic cells, however, hyperoxia did not alter basal PLD activity. Antioxidants, such as propyl gallate and pyrrolidine dithiocarbamate, reversed the effect of hyperoxia on TPA-induced PLD activity. Furthermore, the TPA-induced PLD activation was inhibited not only by the protein kinase C inhibitor, Go6976, but also by the tyrosine kinase inhibitor, genistein, and by the Src kinase specific inhibitor, PP-2, suggesting the involvement of protein kinase C and also tyrosine kinases in TPA-induced PLD activation. Western blot analysis of cell lysates from the hyperoxic (2 or 24 h) BLMVECs stimulated with TPA with anti-phosphotyrosine antibody showed an attenuation in overall tyrosine phosphorylation of proteins. In conclusion, we have demonstrated that hyperoxia enhanced the generation of reactive oxygen species in lung microvascular endothelial cells and attenuated TPA-induced protein tyrosine phosphorylation and PLD activation. As protein tyrosine phosphorylation and PLD play important roles in inflammatory responses, this could provide a mechanism for the regulation of endothelial barrier function during hyperoxic lung injury.
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PMID:Hyperoxia alters phorbol ester-induced phospholipase D activation in bovine lung microvascular endothelial cells. 1271 81

Phosphatidic acid generated by the activation of phospholipase D (PLD) functions as a second messenger and plays a vital role in cell signaling. Here we demonstrate that PLD-dependent generation of phosphatidic acid is critical for Rac1/IQGAP1 signal transduction, translocation of p47(phox) to cell periphery, and ROS production. Exposure of [(32)P]orthophosphate-labeled human pulmonary artery endothelial cells (HPAECs) to hyperoxia (95% O(2) and 5% CO(2)) in the presence of 0.05% 1-butanol, but not tertiary-butanol, stimulated PLD as evidenced by accumulation of [(32)P]phosphatidylbutanol. Infection of HPAECs with adenoviral constructs of PLD1 and PLD2 wild-type potentiated hyperoxia-induced PLD activation and accumulation of O(2)(.)/reactive oxygen species (ROS). Conversely, overexpression of catalytically inactive mutants of PLD (hPLD1-K898R or mPLD2-K758R) or down-regulation of expression of PLD with PLD1 or PLD2 siRNA did not augment hyperoxia-induced [(32)P]phosphatidylbutanol accumulation and ROS generation. Hyperoxia caused rapid activation and redistribution of Rac1, and IQGAP1 to cell periphery, and down-regulation of Rac1, and IQGAP1 attenuated hyperoxia-induced tyrosine phosphorylation of Src and cortactin and ROS generation. Further, hyperoxia-mediated redistribution of Rac1, and IQGAP1 to membrane ruffles, was attenuated by PLD1 or PLD2 small interference RNA, suggesting that PLD is upstream of the Rac1/IQGAP1 signaling cascade. Finally, small interference RNA for PLD1 or PLD2 attenuated hyperoxia-induced cortactin tyrosine phosphorylation and abolished Src, cortactin, and p47(phox) redistribution to cell periphery. These results demonstrate a role of PLD in hyperoxia-mediated IQGAP1 activation through Rac1 in tyrosine phosphorylation of Src and cortactin, as well as in p47(phox) translocation and ROS formation in human lung endothelial cells.
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PMID:Phospholipase D-mediated activation of IQGAP1 through Rac1 regulates hyperoxia-induced p47phox translocation and reactive oxygen species generation in lung endothelial cells. 1936 6