In order to elucidate the role of platelet activating factor (PAF) in the acute lung injury induced by endotoxin (ETX), activities of phospholipase A2, lyso PAF acetyltransferase and oxidative stress by neutrophilic respiratory burst were probed in the present study. To induce acute lung injury, 100 microgram of E.coli ETX (type 0127; B8) was instilled directly into the tracheae of Sprague-Dawley rats. Five hours after the ETX instillation, induction of acute lung injury was confirmed by lung leak index and protein contents in the bronchoalveolar lavage (BAL) fluid. At the same time, lung phospholipase A2 (PLA2) activity and expression of group I and II secretory type PLA2 were examined. In these acutely injured rats, ketotifen fumarate, known as lyso PAF acetyltransferase inhibitor and mepacrine were administered to examine the role of PAF in the pathogenesis of the acute lung injury. To know the effect of the ETX in the synthesis of the PAF in the lungs, lyso PAF acetyltransferase activity and PAF content in the lungs were measured after treatments of ETX, ketotifen fumarate and mepacrine. In addition, the role of neutrophils causing the oxidative stress after ETX was examined by measuring lung myeloperoxidase (MPO) and enumerating neutrophils in the BAL fluid. To confirm the oxidative stress in the lungs, pulmonary contents of malondialdehyde (MDA) were measured. After instillation of the ETX in the lungs, lung leak index increased dramatically (p < 0.001), whereas mepacrine and ketotifen decreased the lung leak index significantly (p < 0.001). Lung PLA2 activity also increased (p < 0.001) after ETX treatment compared with control, which was reversed by mepacrine and ketotifen (p < 0.001). In the examination of expression of group I and II secretory PLA2, mRNA synthesis of the group II PLA2 was enhanced by ETX treatment, whereas ketotifen and WEB 2086, the PAF receptor antagonist, decreased the expression. The activity of the lysoPAF acetyltransferase increased (p < 0.001) after treatment of ETX, which implies the increased synthesis of PAF by the remodelling of lysoPAF in the lungs. Consequently, the contents of the PAF in the lungs were increased by ETX compared with control (p < 0.001), while mepacrine (p < 0.001) and ketotifen (p < 0.01) decreased the synthesis of the PAF in the lungs of ETX treated rats. The infiltration of the neutrophils was confirmed by measuring and enumerating lung MPO and the neutrophils in the BAL fluid respectively. Compared with control, ETX increased lung MPO and number of neutrophils in BAL significantly (p < 0.001) whereas mepacrine and ketotifen decrerased number of neutrophils (p < 0.001) and MPO (p < 0.05, p < 0.001, respectively). The lung MDA contents were also increased (p <0.001) by ETX treatment, but treatment with mepacrine (p < 0.001) and ketotifen (p < 0.01) decreased the lung MDA contents. Collectively, we conclude that ETX increases PLA2 activity, and that the subsequently increased production of PAF was ensued by the remodelling of the lyso PAF resulting in tissue injury by means of oxidative stress in the lungs.
Acute Lung Injury* ; Animals ; Bronchoalveolar Lavage ; Ketotifen ; Lung* ; Malondialdehyde ; Neutrophils ; Oxidative Stress ; Peroxidase ; Phospholipases A2 ; Platelet Activating Factor ; Quinacrine ; Rats ; Rats, Sprague-Dawley ; Respiratory Burst ; RNA, Messenger ; Trachea

No abstract available.
Amino Acids* ; Blastocyst* ; Embryonic Structures*

No abstract available.
Bystander Effect* ; Carcinoma, Hepatocellular* ; Cell Line* ; Ganciclovir* ; Herpes Simplex* ; Phosphotransferases* ; Simplexvirus*

In order to understand the pathogenetic mechanism of adult respiratory distress syndrome (ARDS), the role of phospholipase A2 (PLA2) in association with oxidative stress was investigated in rats. Interleukin-1alpha (IL-1, 50 mug/rat) was used to induce acute lung injury by neutrophilic respiratory burst. Five hours after IL-1 insufflation into trachea, microvascular integrity was disrupted, and protein leakage into the alveolar lumen was followed. An infiltration of neutrophils was clearly observed after IL-1 treatment. It was the origin of the generation of oxygen radicals causing oxidative stress in the lung. IL-1 increased tumor necrosis factor (TNF) and cytokine-induced neutrophil chemoattractant (CINC) in the bronchoalveolar lavage fluid, but mepacrine, a PLA2 inhibitor, did not change the levels of these cytokines. Although IL-1 increased PLA2 activity time-dependently, mepacrine inhibited the activity almost completely. Activation of PLA2 elevated leukotriene C4 and B4 (LTC4 and LTB4), and 6-keto-prostaglandin F2alpha (6-keto-PGF2alpha) was consumed completely by respiratory burst induced by IL-1. Mepacrine did not alter these changes in the contents of lipid mediators. To estimate the functional changes of alveolar barrier during the oxidative stress, quantitative changes of pulmonary surfactant, activity of gamma glutamyltransferase (GGT), and ultrastructural changes were examined. IL-1 increased the level of phospholipid in the bronchoalveolar lavage (BAL) fluid, which seemed to be caused by abnormal, pathological release of lamellar bodies into the alveolar lumen. Mepacrine recovered the amount of surfactant up to control level. IL-1 decreased GGT activity, while mepacrine restored it. In ultrastructural study, when treated with IL-1, marked necroses of endothelial cells and type II pneumocytes were observed, while mepacrine inhibited these pathological changes. In histochemical electron microscopy, increased generation of oxidants was identified around neutrophils and in the cytoplasm of type II pneumocytes. Mepacrine reduced the generation of oxidants in the tissue produced by neutrophilic respiratory burst. In immunoelectron microscopic study, PLA2 was identified in the cytoplasm of the type II pneumocytes after IL-1 treatment, but mepacrine diminished PLA2 particles in the cytoplasm of the type II pneumocyte. Based on these experimental results, it is suggested that PLA2 plays a pivotal role in inducing acute lung injury mediated by IL-1 through the oxidative stress by neutrophils. By causing endothelial damage, functional changes of pulmonary surfactant and alveolar type I pneumocyte, oxidative stress disrupts microvascular integrity and alveolar barrier.
Acute Lung Injury ; Animals ; Bronchoalveolar Lavage ; Bronchoalveolar Lavage Fluid ; Cytokines ; Cytoplasm ; Endothelial Cells ; gamma-Glutamyltransferase ; Insufflation ; Interleukin-1 ; Interleukin-1alpha* ; Leukotriene C4 ; Lung Injury* ; Lung* ; Microscopy, Electron ; Necrosis ; Neutrophils ; Oxidants ; Oxidative Stress ; Phospholipases A2 ; Pneumocytes ; Pulmonary Surfactants ; Quinacrine ; Rats ; Reactive Oxygen Species ; Respiratory Burst ; Respiratory Distress Syndrome, Adult ; Trachea ; Tumor Necrosis Factor-alpha

The role of phospholipase A2 (PLA2) in acute lung leak induced by intestinal ischemia was investigated in association with neutrophilic respiratory burst. To induce lung leak, we generated intestinal ischemia for 60 min prior to the 120 min reperfusion by clamping superior mesenteric artery in Sprague-Dawley rats. Acute lung leak was confirmed by the increased lung leak index and protein content in bronchoalveolar fluid. These changes were inhibited by mepacrine, the non-specific PLA2 inhibitor. The lung myeloperoxidase (MPO) activity denoting the pulmonary recruitment of neutrophils was increased by intestinal I/R, but decreased by mepacrine. Simultaneously, the number of leukocytes in bronchoalveolar fluid was increased by intestinal ischemia/reperfusion (I/R) and decreased by mepacrine. Gamma glutamyl transferase activity, an index of oxidative stress in the lung, was increased after intestinal I/R but decreased by mepacrine, which implicates that PLA2 increases oxidative stresscaused by intestinal I/R. The PLA2 activity was increased after intestinal I/R not only in the intestine but also in the lung. These changes were diminished by mepacrine. In the cytochemical electron microscopy to detect hydrogen peroxide, intestinal I/R increased the generation of the hydrogen peroxide in the lung as well as in the intestine. Expression of interleukin-1 (IL-1) in the lung was investigated through RT-PCR. The expression of IL-1 after intestinal I/R was enhanced, and again, the inhibition of PLA2 suppressed the expression of IL-1 in the lung. Taken together, intestinal I/R seems to induce acute lung leak through the activation of PLA2, the increase of IL-1 expression associated with increased oxidative stress by neutrophilic respiratory burst.
Acute Lung Injury* ; Constriction ; Free Radicals* ; Hydrogen Peroxide ; Interleukin-1 ; Intestines ; Ischemia ; Leukocytes ; Lung ; Mesenteric Artery, Superior ; Microscopy, Electron ; Neutrophils ; Oxidative Stress ; Peroxidase ; Phospholipases A2* ; Phospholipases* ; Quinacrine ; Rats, Sprague-Dawley ; Reperfusion ; Respiratory Burst ; Respiratory Distress Syndrome, Adult ; Transferases

PURPOSE: Dual reporter gene imaging has several advantages for more sophisticated molecular imaging studies such as gene therapy monitoring. Herein, we have constructed hepatoma cell line expressing dual reporter genes of sodium iodide symporter (NIS) and enhanced green fluorescence protein (EGFP), and the functionalities of the genes were evaluated in vivo by nuclear and optical imaging. MATERIALS AND METHODS: A pRetro-PN vector was constructed after separating NIS gene from pcDNA-NIS. RSV-EGFP-WPRE fragment separated from pLNRGW was cloned into pRetro-PN vector. The final vector expressing dual reporter genes was named pRetro-PNRGW. A human hepatoma (HepG2) cells were transfected by the retrovirus containing NIS and EGFP gene (HepG2-NE). Expression of NIS gene was confirmed by RT-PCR, radioiodine uptake and efflux studies. Expression of EGFP was confirmed by RT-PCR and fluorescence microscope. The HepG2 and HepG2-NE cells were implanted in shoulder and hindlimb of nude mice, then fluorescence image, gamma camera image and I-124 microPET image were undertaken. RESULTS: The HepG2-NE cell was successfully constructed. RT-PCR showed NIS and EGFP mRNA expression. About 50% of cells showed fluorescence. The iodine uptake of NIS-expressed cells was about 9 times higher than control. In efflux study, T(1/2) of HepG2-NE cells was 9 min. HepG2-NE xenograft showed high signal-to-background fluorescent spots and higher iodine-uptake compared to those of HepG2 xenograft. CONCLUSION: A hepatoma cell line expressing NIS and EGFP dual reporter genes was successfully constructed and could be used as a potential either by therapeutic gene or imaging reporter gene.
Animals ; Carcinoma, Hepatocellular* ; Cell Line* ; Clone Cells ; Fluorescence* ; Gamma Cameras ; Genes, Reporter* ; Genetic Therapy ; Hep G2 Cells ; Heterografts ; Hindlimb ; Humans ; Iodine ; Ion Transport* ; Mice ; Mice, Nude ; Molecular Imaging ; Optical Imaging ; Retroviridae ; RNA, Messenger ; Shoulder ; Sodium Iodide* ; Sodium*