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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism by which soluble mediators of immune cell origin depress myocardial contractility, either globally as in systemic sepsis, or regionally in areas of inflammatory myocardial infiltrates, remains unclear. When freshly isolated ventricular myocytes from adult rat hearts were preincubated for at least 24 h in medium conditioned by endotoxin (LPS)-activated rat alveolar macrophages, their subsequent inotropic response to the beta-adrenergic agonist isoproterenol was reduced from 225 +/- 19% to 155 +/- 10% of the baseline amplitude of shortening (mean +/- SEM, P < 0.05). Neither baseline contractile function nor the contractile response to high extracellular calcium were affected. To determine whether an endogenous nitric-oxide (NO)-signaling pathway within ventricular myocytes was responsible for their decreased responsiveness to isoproterenol, the L-arginine analogue L-NMMA was added to the preincubation medium. While L-NMMA did not affect baseline contractile function or the response of control myocytes to isoproterenol, it completely restored the positive inotropic response to isoproterenol in myocytes preincubated in LPS-activated macrophage medium. Release of NO by ventricular myocytes following exposure to activated macrophage medium was detected as an increase in cGMP content in a reporter-cell (RFL-6) bioassay and also as increased nitrite content in myocyte-conditioned medium. Thus, the depressed contractile response of adult rat ventricular myocytes to beta-adrenergic agonists by a 24-h exposure to soluble inflammatory mediators is mediated at least in party by induction of an autocrine NO signaling pathway.
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PMID:Abnormal contractile function due to induction of nitric oxide synthesis in rat cardiac myocytes follows exposure to activated macrophage-conditioned medium. 848 92

In each of 4 horses, sterile synovitis was induced by intra-articular injection of 3 micrograms of Escherichia coli endotoxin (lipopolysaccharide, LPS) into one antebrachiocarpal joint; an equal volume (2 ml) of phosphate-buffered saline solution (PBSS) was injected into the opposite, control carpus. Blood and 1.5 ml of synovial fluid were obtained at postinjection hours (PIH) 0, 2, 4, 8, 12, 18, 42, 66, and 144. Synovial fluid sample collection was accomplished by use of an indwelling, intra-articular catheter through PIH 12, and by arthrocentesis subsequently. Joint fluid samples were analyzed for cell counts, protein concentration, cytologic variables, and tumor necrosis factor (TNF), interleukin 6 (IL-6), and prostaglandin E2 (PGE2) values. Tumor necrosis factor and IL-6 activities and WBC count were also measured in blood. To monitor local inflammation, skin temperature of each carpus was imaged, using a thermographic scanner prior to each sample collection time. Horses had minimal systemic effects. Mean (+/- SEM) rectal temperature increased significantly to 39.02 +/- 0.15 C only at PIH 18 after intra-articular injection of LPS. One horse had signs of mild depression from PIH 7 to 18, but its vital signs did not change appreciably. Each horse had mild signs of discomfort in the LPS-injected limb from PIH 1 to 3 until PIH 8 to 10. Mean peak surface temperature of the LPS-injected carpi was significantly higher than that of control carpi from PIH 8 to 144 (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of intra-articularly administered endotoxin on clinical signs of disease and synovial fluid tumor necrosis factor, interleukin 6, and prostaglandin E2 values in horses. 849 39

Other investigators have shown that exogenously administered transforming growth factor-beta (TGF-beta) inhibits lymphocyte adherence to vascular endothelial cells (VEC). We examined the role of TGF-beta 1 as an autocrine mediator of lymphocyte adhesion to adult human VECs. VECs were harvested from eight saphenous or cadaveric iliac veins using 0.2% collagenase. Low-passage VECs in MCDB + 0.1% BSA were pretreated for 24 hr with monoclonal anti-TGF-beta 1 antibody (5 micrograms/ml), LPS (5 micrograms/ml), or IL-1 (10 U/ml). Adherence of fluorescently labeled lymphocytes to pretreated VECs was quantitated and results were expressed as relative adhesion compared to untreated control. Total mRNA from LPS- or IL-1-treated VECs was subjected to Northern analysis to determine relative TGF-beta 1 expression. Total TGF-beta 1 protein concentration in supernatants from LPS- or IL-1-treated VECs was determined by ELISA. Data (means +/- SEM) were analyzed by ANOVA with a Newman-Keuls posttest. Neutralizing endogenous TGF-beta 1 with anti-TGF-beta 1 antibody significantly increased adhesion of lymphocytes to VEC monolayers compared to control (125 +/- 3 vs 101 +/- 2%, P < 0.01, n = 8). The level of adhesion was equivalent to that seen with IL-1 stimulation (131 +/- 6%). Spearman correlation of lymphocyte adherence to IL-1- or LPS-treated VECs vs TGF-beta 1 mRNA expression or vs relative TGF-beta 1 protein concentration showed significant inverse relationships (r = -0.82, P < 0.001, and r = -0.87, P < 0.001, respectively). Endogenous TGF-beta 1's inhibitory effect on lymphocyte adhesion was blocked by a specific neutralizing antibody. VEC TGF-beta 1 mRNA expression and TGF-beta 1 production were inversely proportional to lymphocyte adhesion, suggesting down-regulation of TGF-beta 1 in response to proinflammatory cytokines. Together, these observations support the hypothesis that TGF-beta 1 has an autocrine inhibitory role in regulation of lymphocyte adhesion to VECs.
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PMID:Transforming growth factor-beta 1 serves as an autocrine inhibitor of human endothelial cell/lymphocyte adhesion. 853 71

A monoclonal antibody (MAB) against equine tumor necrosis factor-alpha (Eq TNF) was used to investigate the role of TNF in cytokine, eicosanoid, and metabolic responses of Miniature Horses given endotoxin. Plasma concentrations of interleukin 6 (IL-6), lactate, thromboxane A2 metabolite, and prostacyclin metabolite (6-keto-PGF1 alpha) were measured in 10 Miniature Horses given 0.25 microgram of lipopolysaccharide (LPS; Escherichia coli O55:B5)/kg of body weight. Five horses were given Eq TNF MAB and 5 were given isotype-matched MAB as control. All horses were given 1.86 mg of antibody/kg by IV infusion, 5 minutes before LPS was given IV. Blood samples were taken 20 minutes before and at multiple intervals for 24 hours after LPS was given. Interleukin 6 bioactivity in plasma was measured, using IL-6-dependent cell line (B9). Eicosanoid activities were assessed by enzyme immunoassay, and plasma lactate concentration was determined enzymatically. Data were analyzed by ANOVA and Tukey's honest significant difference test for significant (P < 0.05) effect of treatment. Horses given Eq TNF MAB had significantly (P < 0.050) lower peak mean +/- SEM IL-6 (59 +/- 29 U/ml), lactate (16 +/- 2.00 mg/dl), and 6-keto-PGF1 alpha (254 +/- 79 pg/ml) values then did horses given control MAB (880 +/- 375 U/ml for IL-6; 26 +/- 0.04 mg/dl for lactate; and 985 +/- 290 pg/ml for 6-keto-PGF1 alpha). There was no effect of anti-TNF treatment on LPS-induced thromboxane A2 metabolite production. Tumor necrosis factor mediated IL-6, lactate, and prostacyclin responses, without affecting thromboxane production in horses given LPS.
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PMID:Effects of tumor necrosis factor blockade on interleukin 6, lactate, thromboxane, and prostacyclin responses in miniature horses given endotoxin. 858 54

In addition to biophysical properties, pulmonary surfactant has immunomodulatory activity. We previously demonstrated that both synthetic (Exosurf) and modified natural surfactant (Survanta) downregulated endotoxin-stimulated inflammatory c ytokine mRNA levels and protein products (tumor necrosis factor-alpha [TNF], interleukin-1-beta [IL-1], interleukin-6 [IL-6]) in human alveolar macrophages. In this study, we report that both Exosurf and Survanta suppress TNF mRNA and secretion (85 +/- 4% mean percent inhibition +/- SEM by Exosurf; 71 +/- 6% by Survanta) by endotoxin-stimulated THP-1, a human monocytic cell line. Because surfactant downregulated inflammatory cytokine production similarly in both normal human alveolar macrophages and the THP-1 cell line, we used this cell line to investigate whether surfactant affected transcriptional mechanisms. Specifically, we examined nuclear factor-kappa B (NF-kappa B) activation because it is crucial in transcriptional regulation of many inflammatory cytokine genes including TNF, IL-1, and IL-6. Electrophoretic mobility shift assays showed that both surfactants decreased activation of NF-kappa B. The presence of both p65 and p50 NF-kappa B components in LPS-activated THP-1 cells was confirmed by specific antibody induction of supershifts in mobility assays. These results are the first to suggest that surfactant's suppressive effects on inflammatory cytokine production may involve transcriptional regulation through inhibition of NF-kappa B activation.
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PMID:Surfactant suppresses NF-kappa B activation in human monocytic cells. 860 Sep 42

The acute inflammatory response to tissue injury and infection is associated with low concentrations of plasma retinol and its specific transport proteins, retinol-binding protein (RBP) and transthyretin (TTR). To examine the kinetics and mechanism of hyporetinemia, we have induced acute inflammation with lipopolysaccharide (LPS, from Pseudomonas aeruginosa) in rats with adequate stores of vitamin A. Twenty-four h after treatment with LPS (50 micrograms i.p. per 100 g body weight) or saline and food withdrawal, plasma retinol equalled 0.72 +/- 0.06 mumol/L (mean +/- SEM) in five LPS-treated rats versus 1.35 +/- 0.1 mumol/L in five saline-treated rats (P < 0.01). Plasma, liver, and kidney RBP and TTR concentrations were also significantly reduced, but liver and kidney retinol concentrations did not differ between treatment groups. The relative abundance of RBP mRNA in liver (LPS treatment compared to saline treatment) was reduced as early as 12 h (0.44 +/- 0.15, n = 4 pairs, P < 0.02), and continued to be reduced at 24 h (0.57 +/- 0.12, n = 5 pairs, P < 0.02). In the kidney this ratio did not change significantly due to LPS treatment. The relative abundance of cellular retinol-binding protein (CRBP) mRNA in liver and kidney also was not affected by LPS treatment. We infer from these data that inflammation-induced hyporetinemia results from a reduction in the hepatic synthesis of RBP and secretion of the retinol-RBP complex. Moreover, the results imply that plasma retinol concentration is a poor indicator of vitamin A status during inflammation.
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PMID:Effects of acute inflammation on plasma retinol, retinol-binding protein, and its mRNA in the liver and kidneys of vitamin A-sufficient rats. 872 49

In vitro pretreatment of human monocytes (MO) with low-dose lipopolysaccharide (LPSp) inhibits TNF release in response to subsequent LPSa activation. Septic patients are often indistinguishable from patients with systemic inflammatory response syndrome (SIRS). We hypothesized that in vivo exposure to "septic" stimuli impairs subsequent LPSa-stimulated MO TNF production in vitro. Human peripheral MO were obtained after informed consent from controls or patients with sepsis, SIRS, or posttrauma [ACCP/SCCM definitions]. Cells were plated in vitro, incubated 24 hr, and then stimulated with 0-1000 ng/ml LPSa for 4 hr. Parallel control MO were incubated in vitro with 100 ng/ml LPSp for 24 hr and then stimulated with 1000 ng/ml LPSa for 4 hr. Supernatant TNF (mean U/ml +/- SEM) was measured by bioassay. ANOVA was used to determine statistical significance. In vitro LPSp pretreatment markedly inhibited subsequent LPSa-stimulated TNF release. In vitro LPSa-stimulated TNF release was likewise significantly inhibited with MO from septic patients compared to controls. Inhibition was more profound in septic patients with shock (not shown). No impaired TNF release was seen with MO from SIRS or trauma patients. In conclusion, in vivo preexposure to inflammatory stimuli in septic patients alters monocyte regulation in a manner similar to in vitro endotoxin tolerance. Provocative in vitro monocyte LPS stimulation may distinguish patients with sepsis and SIRS.
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PMID:In vivo endotoxin tolerance: impaired LPS-stimulated TNF release of monocytes from patients with sepsis, but not SIRS. 920 54

High levels of nitric oxide (NO) have been reported in exhaled air of asthmatic individuals. Because alveolar macrophages (AM) are major producers of cytokines, and bronchoalveolar lavage fluid (BALF) from asthmatic individuals contains increased levels of inflammatory cytokines, this study was undertaken to determine whether NO modified the production of inflammatory cytokines by human AM. AM were obtained from normal volunteers by fiberoptic bronchoscopy. Tumor necrosis factor-alpha (TNF-alpha) production stimulated by lipopolysaccharide (LPS; 0.5 microg/ml) was measured with an enzyme-linked immunosorbent assay (ELISA). NO generated from 2,2-(hydroxynitrosohydrazono)-bis-ethanamine (DETA NONOate) (0.1 to 1.0 mM) inhibited TNF-alpha secretion in a dose-dependent manner. At 1 mM DETA NONOate, mean inhibition (+/- SEM) of TNF-alpha secretion was 56 +/- 4% (P = 0.002). To determine whether this effect was cytokine specific, interleukin-1beta (IL-1beta) and macrophage inflammatory protein-1alpha (MIP-1alpha) were evaluated, and DETA NONOate was also found to inhibit both of these cytokines. Basal cytokine levels from unstimulated AM were unaffected by NO. These findings indicate that NO is a potent inhibitor of cytokine production by stimulated human AM.
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PMID:Nitric oxide inhibits inflammatory cytokine production by human alveolar macrophages. 930 13

We employed a bile duct ligation (BDL) model of cholestatic liver injury to test the hypothesis that this form of preexisting hepatic dysfunction alters the kinetics of circulating TNF-alpha and IL-6 after Escherichia coli endotoxemia, thereby augmenting mortality and lung injury by a TNF-alpha:leukotriene (LT) axis of inflammation. Male rats were catheterized 13 d after BDL or sham surgery and studied while awake 18 to 24 h later. Cholestasis after BDL was confirmed by baseline serum bilirubin (BDL = 7.34 +/- 0.72 mg/dl, mean +/- SEM, n = 17 versus Sham = 0.25 +/- 0.07, n = 20; p < 0.005) and histopathology. Sham and BDL animals received E. coli lipopolysaccharide serotype O55:B5 (LPS, 5 mg/kg i.v.) or 0.9% NaCl (NS) ending at t = 0 and were monitored over 24 h for vital signs and hemodynamics. In parallel studies, lipoxygenase inhibition was performed using diethylcarbamazine or the 5-lipoxygenase activating-protein inhibitor MK-886. Blood was collected at baseline and at t = 1.5, 3.5, and 24 h for formed elements and for serum endotoxin, TNF-alpha, IL-6, bilirubin, and alanine aminotransferase (ALT). Organs were evaluated at 24 h for histopathology, including neutrophil (PMN) densities and wet/dry weight (W/D) ratios. Cholestasis reduced survival after otherwise nonlethal endotoxemia, with seven of 11 BDL + LPS rats dying within 24 h versus no deaths in BDL + NS (n = 6), Sham + LPS (n = 14), or Sham + NS (n = 6) animals (p < 0.01). Despite equivalent serum endotoxin between groups, circulating TNF-alpha was 8-fold higher in BDL + LPS than in Sham + LPS rats at 1.5 and 3.5 h (p < 0.001), whereas serum TNF-alpha did not differ between BDL + NS and Sham + NS rats. IL-6 likewise was increased differentially by 1.5 h in BDL + LPS animals (11.98 +/- 2.42 ng/ml) versus Sham + LPS rats (3.05 +/- 0.58 ng/ml, p < 0.05). Hypothermia, bradycardic hypotension, and leukopenia were most severe and prolonged in BDL + LPS rats, which also had significantly higher ALT values, W/D ratios, and organ PMN counts. LT inhibition failed to reduce BDL-related differences in serum cytokines or survival after endotoxemia. Thus, cholestasis augments inflammatory responses to gram-negative endotoxemia, sensitizing the host to enhanced fluid flux in multiple organs and to mortality by a LT-independent mechanism.
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PMID:Cholestatic liver injury increases circulating TNF-alpha and IL-6 and mortality after Escherichia coli endotoxemia. 960 37

This study examined whether pretreating rats with endotoxin (lipopolysaccharide, LPS) modifies the retardation of the gastric emptying of liquids induced by this same toxin. Male SPF Wistar rats (8-10 weeks old, 230-300 g) were divided into four groups of eight animals each that received either the vehicle solution sterile pyrogen free saline or LPS (50 mg/kg, intravenously), 96 and 5 hours before the measurement of gastric emptying. The four groups were defined on the basis of the sequence of intravenous injections namely saline + saline, saline + LPS, LPS + saline, and LPS + LPS. All the animals were fasted for 24 hours before and after the first injection and then received food ad libitum for the next 48 hours, before being fasted again for 24 hours prior to the evaluation of gastric emptying. Throughout these periods, the rats had free access to water that was only withdrawn 1 h before the study. A saline solution containing red phenol was used as the test meal. Gastric retention (GR) was measured between 2 and 4 p.m. 120 minutes after the orogastric administration of the meal. The results showed that in the saline + LPS group the GR (mean +/_ SEM = 61.1 +/_ 2.6%) was significantly greater (P < 0.05, Tukey test) than in relation to the saline + saline group (40.5 +/_ 2.6%). On the other hand, there were no significantly differences between the animals which received LPS + LPS (41.8 +/_ 2.5%) and those receiving LPS + saline (37.5 +/- 1.8%) or between these the groups and those receiving saline on both occasions. In conclusion the pretreatment with LPS suppressed the effect of endotoxin on gastric emptying by inducing early tolerance in the motor activity of the stomach in a manner similar to that described for other systems
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PMID:Effect of tolerance to bacterial lipopolysaccharide on gastric emptying in rats. 962 17


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