Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UNIPROT:P43026 (lipopolysaccharide)
62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The effects of bradykinin on nociceptors have been characterized on a preparation of the neonatal rat spinal cord with functionally connected tail maintained in vitro. Administration of bradykinin to the tail activated capsaicin-sensitive peripheral fibres and evoked a concentration-dependent (EC50 = 130 nM) depolarization recorded from a spinal ventral root (L3-L5). 2. The response to bradykinin was unaffected by the peptidase inhibitors, bestatin (0.4 mM), thiorphan (1 microM), phosphoramidon (1 microM) and MERGETPA (10 microM) or by the presence of calcium blocking agents, cadmium (200 microM) and nifedipine (10 microM). 3. Inhibition of cyclo-oxygenase with indomethacin (1-5 microM), aspirin (1-10 microM) and paracetamol (10-50 microM) consistently attenuated responses to bradykinin. 4. The effect of bradykinin was mimicked by the phorbol ester PDBu, an activator of protein kinase C. The response to bradykinin was attenuated following desensitization to PDBu but desensitization to bradykinin did not induce a cross-desensitization to PDBu. The protein kinase C inhibitor staurosporine (10-500 nM) consistently attenuated the effects of PDBu and bradykinin. 5. Bradykinin responses were reversibly enhanced by dibutyryl cyclic AMP (100 microM). However dibutyryl cyclic GMP (0.5 mM) and nitroprusside (10 microM) produced prolonged block of responsiveness to bradykinin. Prolonged superfusion with pertussis toxin did not affect responses to bradykinin. 6. The B1-receptor agonist des Arg9-bradykinin (10-100 microM) was ineffective alone or after prolonged exposure of the tail to lipopolysaccharide (100 ng ml-1) or epidermal growth factor (100 ng ml-1) to induce B1 receptors. The BI-receptor antagonist, des Arg9 Leu8-bradykinin (10 JM) did not attenuate the response to bradykinin. A number of bradykinin B2 antagonists selectively and reversibly attenuated the response to bradykinin. The rank order potency was Hoe 140> LysLys [Hyp3,Thi5 8,D-Phe7]-bradykinin> D-Arg[Hyp3, Thi5'8, D-Phe7]-bradykinin = D-Arg[Hyp2,Thi5'8, D-Phe7]-bradykinin.7. These data show that bradykinin produces concentration-dependent activation of peripheral nociceptors in the neonatal rat tail. The responses were unaffected by calcium channel block and were partially dependent on the production of prostanoids. Bradykinin-evoked responses were consistent with the activation of protein kinase C-dependent mechanisms. Cyclic GMP-dependent mechanisms may be involved in bradykinin-receptor desensitization whereas cyclic-AMP dependent mechanisms increase fibre excitability and facilitate bradykinin-induced responses. The effects of bradykinin were mediated by a B2 receptor.
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PMID:Bradykinin-induced activation of nociceptors: receptor and mechanistic studies on the neonatal rat spinal cord-tail preparation in vitro. 133 51

Drug-induced gingival overgrowth is an adverse side effect associated principally with 3 different types of drugs; specifically the antiepileptic phenytoin, the calcium channel antagonist nifedipine, and the immunosuppressant cyclosporin. The present study has analyzed the effect of cyclosporin and lipopolysaccharide on fibroblasts from 3 different sources: 1) normal healthy human gingiva (NHGF); 2) overgrown gingiva from 2 patients taking cyclosporin (CHGF); and 3) human fetal lung (WI-38). Fibroblasts isolated from cyclosporin-associated gingival overgrowth were significantly less responsive to cyclosporin in terms of DNA, total protein, and proteoglycan synthesis. This finding supports the in vivo response where few fibroblasts are seen but marked overgrowth of fibrous tissue occurs. Lipopolysaccharide derived from Fusobacterium nucleatum and Escherichia coli was capable of inhibiting DNA synthesis significantly in all 3 fibroblast types. Total protein synthesis by CHGF cells was inhibited differentially by Fusobacterium nucleatum LPS and addition of cyclosporin to this system resulted in reversal of the inhibition. A synergistic effect was noted when the proteoglycan output of NHGF cells was assessed in response to co-incubation with cyclosporin and Escherichia coli LPS. The study shows that bacterial LPS may be an important co-factor in the pathogenesis of cyclosporin-induced gingival overgrowth.
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PMID:The effect of cyclosporin and lipopolysaccharide on fibroblasts: implications for cyclosporin-induced gingival overgrowth. 152 83

Macrophage cytocidal activation requires the sequential impingement on the macrophage of a priming stimulus (interferon [IFN] alpha, beta, or gamma) and a triggering stimulus (such as polyinosinic acid:polycytidylic acid [poly [I:C]] or bacterial lipopolysaccharide). The mechanism of progression from the IFN-primed state to the cytocidal state is poorly understood. By quantifying the level of expression of a gene product (complement component factor B [Bf]) associated with cytocidal activation and through the use of phenotypically distinct populations of macrophages (unprimed and IFN-primed), we have investigated the functional necessity of changes in intracellular concentration of free calcium ions ([Ca2+]i) in signaling the transition from the primed to the cytocidal state. Elevating the [Ca2+]i by incubation of unprimed macrophages with the calcium ionophore, ionomycin, failed to induce the expression of Bf. By contrast, Bf was expressed at high levels when IFN-primed macrophages were exposed to ionomycin, suggesting that priming induced within the macrophages the capacity to respond to a nonspecific change in [Ca2+]i. Quantification of the [Ca2+]i in response to exposure to ionomycin revealed an initial transient elevation, followed by a secondary sustained component. No differences in these changes were observed between unprimed and IFN-primed macrophages. We therefore questioned if changes in [Ca2+]i were also implicated in the transition between the primed and the cytocidal state using the ligand, poly [I:C]. In contrast to ionomycin, incubation of IFN-primed macrophages with poly [I:C] did not sustain measurable increases in [Ca2+]i, yet fully stimulated the transition from the IFN primed to the cytocidal state. However, incubation of IFN-primed macrophages with poly [I:C] in the presence of 1) a Ca2+/ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid buffer calculated to clamp the extracellular concentration of free calcium ions to a value approximately equal to the resting [Ca2+]i; 2) the calcium channel blocker verapamil; or 3) the intracellular Ca2+ antagonists (W-7, W-13, and TMB-8) substantially inhibited the induction of Bf. Collectively, these data support the following conclusions. First, that changes in [Ca2+]i comprise an important element in the induction of progression from the IFN-primed to the cytocidal state. Second, the failure to detect global changes in [Ca2+]i in response to the ligand, poly [I:C], suggests that changes in [Ca2+]i or Ca2+ movement may occur in either a spatially restricted or in an asynchronous cyclical fashion and are not detected by population fluorescence measurements. Third, the source of the relevant Ca2+ is extracellular. Fourth, our findings suggest that priming influences macrophage functional responses at a locus that is distal to the changes in [Ca2+]i, thereby potentially allowing signaling processes to be utilized to initiate different cellular responses.
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PMID:Transmembrane-mediated changes in [Ca2+] are involved in the signaling pathway leading to macrophage cytocidal differentiation: implications of localized changes in intracellular [Ca2+] and of interferon priming on Ca2+ utilization. 162 33

The mortality of sepsis/septic shock continues to be high in newborns. However, there is no established method in its treatment. Although calcium channel blockers ameliorate the hemodynamic deterioration of adult circulatory shock, their effects on newborn endotoxic shock have not been elucidated. This study was performed in newborn dogs to investigate the effects of diltiazem on newborn endotoxic shock. Endotoxic shock was induced in newborn dogs (2-10 days old, 300-800 g) by an intravenous injection of E. coli lipopolysaccharide (LPS; 1.5 mg/kg), and diltiazem (DZ) at the dose of 300, 600 or 1200 micrograms/kg was administered intravenously 20 min prior to LPS injection. Hemodynamic changes were serially observed until 120 min after LPS injection. The heart rate, mean arterial pressure and cardiac output decreased after LPS injection, and systemic vascular resistance decreased. DZ at the dose of 600 micrograms/kg attenuated the decreases of MAP and cardiac output, but 300 and 1200 micrograms/kg of DZ exacerbated them. DZ at the dose of 1200 micrograms/kg decreased the heart rate, and DZ at all three doses attenuated the increase of systemic vascular resistance. Therefore, 600 micrograms/kg of DZ is beneficial in the treatment of endotoxic shock in newborn dogs.
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PMID:Diltiazem treatment in newborn canine endotoxic shock. 208 81

The addition of lipopolysaccharide (LPS) from Gram-negative bacteria to whole blood induced a consistent enhancement of platelet impedance aggregation (WB-PIA) and an increase in median platelet volume (MPV). In contrast, the addition of LPS to platelet rich plasma (PRP) resulted in inconsistent changes in turbidometric platelet aggregation (TPA) and no significant change in MPV. The LPS-induced increase of MPV in whole blood was inhibited by verapamil, a calcium channel blocker. We conclude that: (a) LPS consistently activates platelets in whole blood but not in PRP; (b) LPS-induced activation of platelets is probably mediated by products released by leucocytes and/or erythrocytes; (c) the increase in MPV induced by LPS is probably dependent upon calcium influx; and (4) an increase in MPV may be a useful and sensitive model for the study of platelet activation by LPS, in vitro and in vivo.
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PMID:An investigation into the effects of bacterial lipopolysaccharide on human platelets. 279 18

The purpose of these studies was to establish whether extracellular calcium (Cao2+) plays a role in the process of activation of RAW-264 macrophages for tumor cell killing. We found that these cells were capable of developing a significant level of cytolytic activity under treatment with lymphokine (LK) and lipopolysaccharide (LPS), in the absence of Cao2+ and that responses developed in Ca2+-free media were only 6-18% lower in comparison with the responses developed in the presence of Cao2+. The determination of 45calcium uptake in RAW-264 cells treated with LK and LPS showed that the rate of 45calcium uptake has displayed no increase during either the course of activation or in activated, highly cytolytic cells. Finally, three calcium channel blockers examined here: verapamil, diltiazem and flunarizine, with concentrations ranging from 1 X 10(-7) M - 2.5 X 10(-5) M, showed no inhibitory effect on the process of activation. Nifedipine, another calcium channel blocker, inhibited the development of cytolytic activity with concentrations ranging from 1 X 10(-6) M - 2.5 X 10(-5) M. It could be argued, however, that this inhibition was nonspecific, since this agent was 13 times more potent with regard to the calcium ionophore A23187-induced release of beta-glucuronidase, the function which is entirely dependent on Cao2+. Taken together, these results suggest that Cao2+ is not an absolute requirement for the process of tumoricidal activation of RAW-264 macrophages but it may play some supportive role in this process.
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PMID:Extracellular calcium is not an absolute requirement for tumoricidal activation of RAW-264 macrophage-like cell line. 346 Oct 96

Incubation of murine spleen cells, or enriched T-cell populations, with the T-cell-dependent polyclonal mitogens Con-A or PHA resulted in a dose-dependent increase in 45Ca2+ uptake. This effect was observed after a delay of about 30 to 60 min, reached a maximum after 2-4 h and lasted up to 6 h. Similarly, the calcium ionophore A23187 caused an increased Ca2+ uptake, although this was faster, occurring within a few minutes, reaching a maximum at 15 min and lasting for about 2-4 h. No change in Ca2+ uptake was observed using a specific B-cell mitogen (lipopolysaccharide) or B-cell preparations. Nifedipine, a calcium channel-blocking agent, inhibited activation of lymphocytes in a primary immune response (mixed lymphocyte reaction and formation of plaque forming cells in vitro) but was unable to interfere with proliferating cell lines or a secondary immune response. Incubation of Con-A-activated lymphocytes with the immunosuppressive agent CS-A caused an additional increase in calcium uptake, whereas no change in calcium uptake was observed when resting lymphocytes or B-cells activated by LPS were incubated with cyclosporin. A similar potentiation of Con-A-induced calcium uptake was seen with hydrocortisone, but not with cytostatic agents or anti-lymphocyte serum. Submaximal calcium uptake induced by the ionophore A23187 was potentiated by CS-A and hydrocortisone as well as by cytostatic agents and ALS.
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PMID:Cyclosporin A (Sandimmun) modulates the Ca2+ uptake of mitogen-stimulated lymphocytes. 644 37

We investigated whether calcium channel antagonists would alter the induction of nitric oxide (NO) synthesis by bacterial lipopolysaccharide (LPS) alone or in combination with interferon-gamma (IFN gamma) in cultured J774 macrophages, rat vascular smooth muscle cells, rat renal mesangial cells, and rat cardiac myocytes. The induction of NO synthesis was determined by measuring nitrite, the stable end-product. The dihydropyridine calcium channel antagonists, nifedipine, manidipine, nitrendipine, benidipine, barnidipine, perdipine, and nilvadipine all reduced the LPS-induced nitrite production in a dose-dependent manner, each with a differing half-maximal inhibitory concentration, in cultured J774 macrophages. Nifedipine also inhibited nitrite production in vascular smooth muscle cells, mesangial cells, and cardiac myocytes. The half-maximal inhibitory concentrations of nifedipine were ranked as follows: smooth muscle cells < mesangial cells < cardiac myocytes. Diltiazem, at nontoxic concentrations, had no effect on the nitrite formation in the three cell types. Verapamil markedly increased the formation of nitrite in cardiac myocytes in response to LPS and IFN gamma, but not in vascular smooth muscle or mesangial cells. Exposure of cardiac myocytes to LPS and IFN gamma caused the expression of NO synthase mRNA that was significantly increased by verapamil. Thus, certain calcium channel antagonists modulate NO synthesis by altering the induction of NO synthase.
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PMID:Effects of calcium channel antagonists on the induction of nitric oxide synthase in cultured cells by immunostimulants. 747 30

Mononuclear cell infiltration and local cytokine elaboration are hallmarks of inflammatory and immunologic heart diseases. To test the hypothesis that cytokines can modulate cardiac myocyte growth and phenotype, myocytes cultured from neonatal rat hearts were exposed to IL-1 beta, an inflammatory cytokine prevalent in myocardial inflammation. IL-1 beta (2 ng/ml, 24 h) increased [3H]leucine incorporation by 30 +/- 4% (P < 0.001, n = 29) and net cellular protein content by 20 +/- 4% (P < 0.001, n = 27), but had no effect on DNA synthesis. Northern hybridization showed that IL-1 beta increased prepro-atrial natriuretic factor (ANF) mRNA (5.8 +/- 1.5-fold, P < 0.01, n = 13) and beta-myosin heavy chain (beta-MHC) mRNA (> 10-fold, n = 4), and decreased mRNA levels for sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2) (-46 +/- 7%; P < 0.001; n = 11), calcium release channel (CRC) (-65 +/- 11%, P < 0.001, n = 8) and voltage-dependent calcium channel (VDCC) (-53 +/- 7%, P < 0.001, n = 8). NG-monomethyl-L-arginine (1 mM), an inhibitor of nitric oxide (NO) synthesis, did not inhibit the IL-1 beta-induced protein synthesis or changes in mRNA levels. In ventricular myocardium obtained from adult rats treated with lipopolysaccharide (4 mg/kg intraperitoneally 18 h) to stimulate systemic cytokine production, there were changes in the mRNA levels for beta-MHC (6 +/- 1-fold, P < 0.01, n = 4), SERCA2 (-65 +/- 4%, P < 0.0001, n = 4), CRC (-67 +/- 5%, P < 0.001, n = 4), and VDCC (-58 +/- 5%, P < 0.001; n = 4) that were qualitatively similar to those observed in cultured myocytes. Thus, IL-1 beta, acting via an NO-independent mechanism, caused myocyte hypertrophy associated with induction of fetal genes (ANF and beta-MHC) and downregulation of three important calcium regulatory genes (SERCA2, CRC, and VDCC). IL-1 beta may contribute to the abnormal structural and functional alterations of cardiac myocytes in conditions marked by mononuclear cell infiltration.
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PMID:Interleukin-1 beta modulates the growth and phenotype of neonatal rat cardiac myocytes. 763 44

We investigated the effect of the calcium channel antagonist nifedipine on the induction of nitric oxide synthase (NOS) by bacterial endotoxin (lipopolysaccharide; LPS) in J774.2 macrophages, in cultured rat aortic smooth muscle cells and in a rat model of endotoxin shock. Stimulation by LPS for 24 hr increased nitrite accumulation in the supernatant of both cell types. NOS induction accounts for this nitrite accumulation, as both NG-methyl-L-arginine and cycloheximide reduced nitrite production in both cell types. Dexamethasone inhibited LPS-stimulated nitrite production in macrophages, but not in rat aortic smooth muscle cells. Nifedipine inhibited the production of nitrite in these LPS-treated cell types, with a more pronounced effect on macrophages. However, nifedipine did not inhibit the production of nitrite in J774.2 cells in which NOS had already been induced by prior exposure to LPS, and any possible further induction was inhibited by cycloheximide. In anesthetized rats subjected to LPS, pretreatment with nifedipine or dexamethasone ameliorated the fall in mean arterial blood pressure and the vascular hyporeactivity to norepinephrine at 180 min after LPS injection. At 180 min after LPS, an increase in a calcium-independent (induced) NOS activity was measured in lung homogenates. This induced NOS activity was reduced in lungs from rats treated with nifedipine or dexamethasone before LPS. Thus, nifedipine inhibits the induction of NOS in response to LPS in cultured cells in vitro and in the anesthetized rat.
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PMID:Nifedipine inhibits the induction of nitric oxide synthase by bacterial lipopolysaccharide. 768 45


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