Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumor necrosis factor alpha (TNF alpha) is likely to exert a major influence in the pathogenesis of glomerulopathies. Besides its proinflammatory properties. TNF alpha interacts with cell growth and synthesis of components of the fibrinolytic system. In this study, we report the effects of recombinant human TNF alpha on the synthesis of tissue-type plasminogen activator (t-PA) and its inhibitor (PAI-1) by human mesangial cells in culture. We first demonstrate that TNF alpha binds specifically to a single class of high affinity receptors (Kd 5.10(-11) M; 1500 receptors/cell). TNF alpha has an antimitogenic effect on human mesangial cells since it decreased DNA synthesis, measured by 3H-thymidine incorporation, in a dose-dependent manner. Release of cytosolic LDH and incorporated 51Cr was not increased by 100 ng/ml TNF alpha as compared with control, indicating that this monokine is not cytotoxic for cultured human mesangial cells. Zymographic analysis and reverse fibrin autography disclosed a 120 kD t-PA-PAI-1 complex and a 50 kD free form of PAI-1 in the supernatants of both unstimulated and TNF-stimulated cells; PAI-1 was released in excess and free t-PA was not observed. TNF alpha (0 to 100 ng/ml) had no effect on t-PA synthesis, but enhanced PAI-1 release in a time- and dose-dependent manner (97% increase of PAI-1 synthesis after a 24 hour incubation). This effect was abolished by cycloheximide, suggesting that protein synthesis was required. Northern blot analysis showed that TNF alpha increased the steady-state PAI-1 mRNA levels in a time-dependent manner, with a maximal effect at two hours.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Tumor necrosis factor alpha increases antifibrinolytic activity of cultured human mesangial cells. 132 51

A previous study from this laboratory, using morphological and biochemical (LDH release) parameters, has shown that tungsten carbide-cobalt dust exhibits a greater cytotoxicity toward isolated macrophages than cobalt metal powder alone. The present study extends this comparison by examining additional biological parameters. Glucose uptake and superoxide anion production by isolated macrophages were significantly more depressed by the tungsten carbide-cobalt mixture (WC-Co) than by cobalt alone (Co) while pure tungsten carbide (WC) had no effect or even stimulated the cells. For glucose-6-phosphate dehydrogenase and cell-associated plasminogen activator (PA) activities, no difference between Co and WC-Co dusts was observed. These observations add further evidence to our previous findings regarding the different biological reactivity of cobalt metal alone or mixed with tungsten carbide.
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PMID:Biological responses of isolated macrophages to cobalt metal and tungsten carbide-cobalt powders. 165 97

A mathematic model was constructed to investigate conflicting physiologic data concerning the charge effect of continuous capillaries to macromolecules in the lung. We simulated the equilibration kinetics of lactate dehydrogenase (MR 4.2 nM) isozymes LDH 1 (pI = 5.0) and LDH 5 (pI = 7.9) between plasma and lymph using previously measured permeability coefficients, lung tissue distribution volumes (VA) and plasma concentrations (CP) in lung tissue. Our hypothesis is that the fixed anionic charges in interstitium, basement membrane, and cell surfaces determine equilibration rather than charged membrane effects at the capillary barrier, so the same capillary permeability coefficients were used for both isozymes. Capillary filtration rates and protein fluxes were calculated using conventional flux equations. Initial conditions at baseline and increased left atrial pressures (PLA) were those measured in animal studies. Simulated equilibration of isozymes over 30 h in the model at baseline capillary pressures accurately predicted the observed differences in lymph/plasma concentration ratios (CL/CP) between isotopes at 4 h and equilibration of these ratios at 24 h. Quantitative prediction of isozyme CL/CP ratios was also obtained at increased PLA. However, an additional cation selective compartment representing the surface glycocalyx was required to accurately simulate the initial higher transcapillary clearances of cationic LDH 5. Thus experimental data supporting the negative barrier, positive barrier, and no charge barrier hypotheses were accurately reproduced by the model using only the observed differences in interstitial partitioning of isozymes without differences in capillary selectivity.
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PMID:Interstitial distribution of charged macromolecules in the dog lung: a kinetic model. 359 24

In order to evaluate the possible role of the hepatic macrophage (H-M macrophage) in lipopolysaccharide-induced shock and disseminated intravascular coagulation (DIC), a technique has been developed for the isolation and maintenance in culture of rabbit H-M macrophage. Characterization of the resultant cell population by morphology, nonspecific esterase staining, phagocytosis of latex beads, by presence of Fc and C3b membrane receptors confirms a pure population of M macrophage without outgrowth of other cell types for up to 10 days in culture. The exposure in vitro of the H-M macrophage to LPS (either Salmonella minnesota R595 or Escherichia coli 0111:B4) stimulates a selective increase in activity of several cellular enzyme: LDH, lysozyme, plasminogen activator, and a procoagulant factor, with minimal changes in acid phosphatase and beta-glucuronidase detected. Concomitantly, both in vivo and in vitro treatment with LPS produces an apparent direct cellular toxicity. The combined effect of toxicity and selective stimulation and release of mediators in LPS-stimulated H-M macrophage may play a central role in the endotoxemic shock syndrome.
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PMID:The response of isolated rabbit hepatic macrophages (H-M macrophage) to lipopolysaccharide (LPS). 719 47

The purpose of this study is to clarify the effect of burn rabbit serum on the function and structure of endothelial cells in vitro. Morphological study (inverted microscopy, scanning electron microscopy), and determinations of LDH, 6-keto-PGF1 alpha and tissue-type plasminogen activator in the culture medium, changes in the ability of anti-adhesion of platelet to endothelial cells and anti-aggregation property of platelet, etc. were performed. The main results and conclusions were as follows: (1) Rabbit serum obtained in the early stage exerted obvious toxic effects on endothelial cells, functional changes appeared earlier than structural, and in the later changes in intercellular junction and cellular surface appeared earlier; (2) Burn rabbit serum significantly reduced the ability of anti-adhesion of platelet to endothelial cell and anti-aggregation property of platelet, and it might be the primary cause of local micro-thrombosis; (3) Because of the destruction of endothelial surface, the ability of fibrinolysis of endothelial cells was reduced. The activity of tPA might be inhibited b PAI-1, although the content of tPA in the culture medium seemed to be increased after endothelial cell injury.
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PMID:[Endothelial cell injury and changes in anti-coagulation properties induced by burn serum in vitro]. 772 5

Acute exposure of humans to ozone results in reversible respiratory function decrements and cellular and biochemical changes leading to the production of substances which can mediate inflammation and acute lung injury. While pulmonary function decrements occur almost immediately after ozone exposure, it is not known how quickly the cellular and biochemical changes indicative of inflammation occur in humans. Increased bronchoalveolar lavage (BAL) fluid levels of neutrophils (PMNs) and prostaglandins (PGE2) have been reported in humans as early as 3 hr and as late as 18 hr after exposure. The purpose of this study was to determine whether a broad range of inflammatory mediators are elevated in BAl fluid within 1 hr of exposure. We exposed eight healthy volunteers twice: once to 0.4 ppm ozone and once to filtered air. Each exposure lasted for 2 hr during which the subjects underwent intermittent heavy exercise (66 liters/min). BAL was performed 1 hr after the exposure. Ozone induced rapid increases in PMNs, total protein, LDH, alpha-1 antitrypsin, fibronectin, PGE2, thromboxane B2, C3a, tissue factor, and clotting factor VII. In addition, there was a decrease in the recovery of total cells and alveolar macrophages, and decreased ability of alveolar macrophages to phagocytize Candida albicans. A comparison of these changes with changes observed in an earlier study in which subjects underwent BAL 18 hr after an identical exposure regimen indicates that IL-6 and PGE2 levels were higher 1 hr after exposure than 18 hr after exposure, fibronectin and tissue-plasminogen activator levels were higher 18 hr after exposure, and that PMNs, protein, and C3a were present at essentially the same levels at both times. These results indicate that (i) several inflammatory mediators are already elevated 1 hr after exposure; (ii) some mediators achieve their maximal levels in BAL fluid at different times following exposure. These data suggest that the inflammatory response is complex, depending on a cascade of timed events, and that depending on the mediator of interest one must choose an appropriate sampling time.
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PMID:Time-dependent changes of inflammatory mediators in the lungs of humans exposed to 0.4 ppm ozone for 2 hr: a comparison of mediators found in bronchoalveolar lavage fluid 1 and 18 hr after exposure. 865 7

The lung plasminogen activator (PA) response was examined in four different models of particle-induced pulmonary lesions in NMRI mice (single intratracheal administration, 0.75 to 5 mg/mouse). Sequential changes in cellular (total and differential counts) and biochemical markers of alveolitis (lactate dehydrogenase [LDH], total proteins) were monitored in bronchoalveolar fluid (BALF) and the fibrotic lung response was assessed histologically. An intense but spontaneously resolving alveolitis was produced by manganese dioxide (MnO2) and a fibrosing alveolitis was elicited by crystalline silica (DQ12). Minimal and noninflammatory responses were obtained after instillation of titanium dioxide (TiO2) and tungsten carbide (WC), respectively. The comparison between the resolving and the fibrosing alveolitis model was especially taken into consideration in an attempt to identify fibrinolytic changes associated with the development of fibrosis. At the alveolitis stage, similarly increased BALF PA activities were measured in both the resolving and the fibrosing alveolitis models whereas only slight and no PA modifications were noted after administration of TiO2 and WC, respectively. Persistently (up to 120 d) increased BALF PA activity was selectively associated with the progression to fibrosis (DQ12), suggesting that PA is involved in the fibrotic process. ELISA measurements demonstrated that the changes in BALF PA activity were exclusively related to changes in urokinase (uPA), not tissue-type PA. A rapid and persisting (up to Day 30) upregulation of cell-associated PA activity occurred after DQ12, MnO2, and TiO2 treatment only. Cellular PA activity was however significantly higher in fibrogenic inflammatory cells recovered from DQ12 than from MnO2-treated mice suggesting that the intensity of cellular PA upregulation may represent an early indicator of the progression to fibrosis. The implication of urokinase in the pathogenesis of silica-induced fibrosis was demonstrated by the use of a uPA knockout mice. The acceleration of the fibrotic process in uPA-deficient compared with the wild type animals demonstrated the contribution of uPA to limit the fibrotic process.
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PMID:Role of urokinase in the fibrogenic response of the lung to mineral particles. 947 81

We tested the hypothesis that oxidized low-density lipoprotein (oxLDL), administered in sublethal doses to the culture medium of immortalized rat brain endothelial cells (ECs, GP8.39), acts as a prooxidant signal to stimulate peroxidation processes and membrane phospholipid hydrolysis. ECs were grown at confluence in a medium with or without native LDL (nLDL) or oxLDL (1.5 mg/dish; up to 350-450 nmol hydroperoxides/mg protein) for two temporally distinct phases (short incubation period up to 1 h, or long incubation period spanning 24 h). Peroxidation parameters (conjugated dienes, MDA, hydroperoxides and LDH release) and arachidonic acid (AA) release were determined. Cell lysates and subcellular fractions were assayed for cPLA(2) while the cytotoxic effect and apoptosis were monitored by morphological changes, trypan blue dye exclusion, MTT reduction test, caspase-3 activity, COMET and laser confocal fluorescence microscopy (LCFM) analyses. Effects of alpha-tocopherol and 85-kDa PLA(2) inhibitor (AACOCF(3)), alone or in combination, were also tested. Immunoblot analysis of cPLA(2) was carried out on cell fraction proteins. After incubation for 1 or 24 h, oxLDL (100-200 microM hydroperoxides), but not nLDL, markedly increased lipid peroxidation, cPLA(2) activity and AA release in a dose-dependent manner. AACOCF(3) and antioxidant alpha-tocopherol (1 mM) strongly inhibited the prooxidant-stimulated AA release. Long-term exposure (24 h) to oxLDL (100 microM) had no effect on the cPLA(2) protein content as tested by Western immunoblot analysis, while showing a sharp cytotoxic effect on the cells. Caspase-3 activity and LCFM analysis indicated that oxLDL (100/200 microM) were able to trigger an apoptotic process. The results suggest that (i) ECs may be the target of extensive oxidative damage caused by oxLDL; (ii) activation of cPLA(2) mediates liberation of AA; (iii) cPLA(2) expression was not stimulated by long-term exposure to oxLDL; (iv) oxidized specific constituents of oxLDL, acting as regulatory signals, increase the ability of ECs to degrade membrane phospholipids, end products of which are linked to the development of atherosclerotic lesions.
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PMID:Cytosolic phospholipase A2 mediates arachidonoyl phospholipid hydrolysis in immortalized rat brain endothelial cells stimulated by oxidized LDL. 1245 11

Scatophagus argus of the family Scatophagidae inflicts painful wounds in fishermen during handling. The clinical picture is characterized by excruciating and persistent local pain disproportionate to the size of injury, redness, swelling and a throbbing sensation that extends to the limbs, followed by dizziness. The biological properties of the S. argus venom were studied to assess its risk and lethal factors with regard to human welfare. In contrast to other fish venoms, S. argus showed relatively low LD50 (9.8 mg/kg via i.p.). Haemolytic activity in human erythrocytes was recorded. Platelet lysis expressed as LDH activity of lysed cells was dose dependent. S. argus venom failed to induce any clot in human plasma. No PLA(2) activity was found in S. argus venom. Mild proteolytic activity was observed. The injection of venom in mice produced lesions and nociception, which were not inhibited by antihistamine pheniramine maleate, suggesting that histamine was not involved in the inflammatory process. The increase in serum creatine kinase activity indicated myotoxicity. Cytotoxicity on HeLa cells was observed. The spectrum of activity in experimental animals of S. argus crude venom resembles those of other fish venoms previously studied and well correlated to the systemic manifestations that are described for S. argus envenomation.
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PMID:Biological and biochemical properties of Scatophagus argus venom. 1759 79

Mercury has been identified as a risk factor for cardiovascular disease among humans. Through diet, mainly fish consumption, humans are exposed to methylmercury, the biomethylated organic form of environmental mercury. As the endothelium is an important player in homeostasis of the cardiovascular system, here, the authors tested their hypothesis that methylmercury activates the lipid signaling enzyme phospholipase A(2) (PLA(2)) in vascular endothelial cells (ECs), causing upstream regulation of cytotoxicity. To test this hypothesis, the authors used bovine pulmonary artery ECs (BPAECs) cultured in monolayers, following labeling of their membrane phospholipids with [(3)H]arachidonic acid (AA). The cells were exposed to methylmercury chloride (MMC) and then the release of free AA (index of PLA(2) activity) and lactate dehydrogenase (LDH; index of cytotoxicity) were determined by liquid scintillation counting and spectrophotometry, respectively. MMC significantly activated PLA(2) in a dose-dependent (5 to 15 microM) and time-dependent (0 to 60 min) fashion. Sulfhydryl (thiol-protective) agents, calcium chelators, antioxidants, and PLA(2)-specific inhibitors attenuated the MMC-induced PLA(2) activation, suggesting the role of thiols, reactive oxygen species (ROS), and calcium in the activation of PLA(2) in BPAECs. MMC also induced the loss of thiols and increase of lipid peroxidation in BPAECs. MMC induced cytotoxicity in BPAECs as observed by the altered cell morphology and LDH leak, which was significantly attenuated by PLA(2) inhibitors. This study established that PLA(2) activation through thiols, calcium, and oxidative stress was associated with the cytotoxicity of MMC in BPAECs, drawing attention to the involvement of PLA(2) signaling in the methylmercury-induced vascular endothelial dysfunctions.
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PMID:Phospholipase A2 activation regulates cytotoxicity of methylmercury in vascular endothelial cells. 1806 71


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