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

The activity of angiotensin converting enzyme (ACE) released into the culture medium of human umbilical cord vein endothelial cells in culture (HUVEC) for 24-hour incubation with or without various serotypes of lipopolysaccharide (LPS) was unchanged. ACE activity, however, in cell lysate or monolayer HUVEC after 24-hour incubation of various serotypes of LPS except LPS from E. coli, 026:B6, showed significant decrease, compared with no LPS treatment. Cell lysate contained much higher ACE activity than monolayer HUVEC after 24-hour incubation with or without LPS. These findings give rise to speculation that ACE or ACE-like substance might be located not only on the luminal surface, but also in cytoplasm of HUVEC, and also that decrease of ACE activity in the serum of septic adult respiratory distress syndrome (ARDS) patients might be due to reduced synthesis by vascular endothelial cells.
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PMID:[Influence of lipopolysaccharide on angiotensin converting enzyme activity expressed by human umbilical vein endothelial cells in culture]. 217 53

The effect of the selective kinin B1 receptor agonist des-Arg9-BK was studied on blood pressure and on the in vitro aorta of rabbits pretreated 18 h earlier with lipopolysaccharide from E. coli, an infusion of bradykinin or with one of three angiotensin converting enzyme inhibitors captopril, enalapril or teprotide. The hypotensive response in vivo and contractile response seen on the in vitro aorta was selectively increased to des-Arg9-BK in all pretreated groups compared to controls, effects which were blocked by the selective competitive kinin B1 receptor antagonist des-Arg9-[Leu8]BK. Dexamethasone given to lipopolysaccharide pretreated rabbits had no effect on the increased hypotensive response seen with des-Arg9-BK. The skin vascular permeability response to des-Arg9-BK, bradykinin and histamine remained unchanged in the groups pretreated with lipopolysaccharide or captopril compared to controls. The possible mechanism(s) whereby angiotensin converting enzyme inhibitors produce this effect and the possible relevance to the inflammatory side-effects seen with this group of drugs is discussed.
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PMID:Angiotensin converting enzyme inhibitors and expression of des-Arg9-BK (kinin B1) receptors in vivo. 254 Sep 86

Administration of intact lipopolysaccharide from E. coli and S. minnesota to mice produced a lowering of serum angiotensin converting enzyme (ACE). However, when either lipid A or carbohydrate-free endotoxin from S. minnesota-Re595 was administered, a rise in serum ACE occurred. A possible explanation for these respective effects may be related to an indirect effect on lung perfusion, on the one hand, or a direct toxic effect to endothelial cell membranes, on the other.
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PMID:SAR of the effect of endotoxin on serum angiotensin converting enzyme in the mouse. 299 85

The identification of lipopolysaccharide as periodic acid-Schiff positive material, present in the membrane fraction of the fish pathogenic Gram-negative bacterium Aeromonas salmonicida, analyzed by SDS-polyacrylamide gel electrophoresis, is shown. Such analysis has revealed several periodic acid-Schiff positive bands and many membrane proteins among which a pathogenicity-related Mr 54000 protein as a constituent of an additional surface layer outside the outer membrane (Evenberg et al., (1982) Biochim. Biophys. Acta 684, 241-248). The latter protein, designated as additional cell envelope protein or ACE protein, has been purified and characterized in our laboratory (Evenberg and Lugtenberg, (1982) Biochim. Biophys. Acta 684, 249-254). Most strains produce both high and low molecular weight lipopolysaccharide species, presumably corresponding with the presence and (virtual) absence, respectively, of an O-antigenic chain. The property to produce high molecular weight lipopolysaccharide can be lost upon subculturing in laboratory growth media and such is greatly enhanced by the prior loss of the ability to produce ACE protein. Lipopolysaccharide and ACE protein were identified as the major antigens. A new polysaccharide-like antigen, designated as PS-antigen, was detected. Moreover, immunological indications for the presence of a lipoprotein in A. salmonicida are described. The surface localization of the antigens was determined by testing whether preadsorption of antisera by intact cells decreased the binding of IgG to these antigens, or decreased the ability of the sera to agglutinate cells. According to these criteria lipopolysaccharide, ACE protein and PS-antigen are the major surface-located antigens. Material cross-reactive with lipopolysaccharide, ACE protein and PS-antigen has been found in a large number of strains. Several lines of evidence indicate the presence of interactions between ACE protein and lipopolysaccharide. Based on these results a molecular model of the cell envelope of virulent A. salmonicida is presented.
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PMID:Biochemical and immunological characterization of the cell surface of the fish pathogenic bacterium Aeromonas salmonicida. 399 26

Mice treated with Escherichia coli endotoxin (500 micrograms/kg i.p.) 24 and 1 hr before paraquat dichloride (50 mg/kg i.p.) had a 2-fold increase in 7-day cumulative mortality compared to those injected with buffered saline before paraquat. The duration of the prior exposure time to endotoxin appears to be an important determinant of the potentiating effect as more mice died after 24 than 1 hr pretreatment. The potentiating effect of endotoxin on paraquat-induced lethality is not due to increased uptake of the toxicant. Lung values of radioactivity from [14C]paraquat were not significantly different between endotoxin and buffered saline-treated mice. Despite the potentiating effect of endotoxin on paraquat-induced lethality, it appears that the lipopolysaccharide is able to provide some protection to the pulmonary capillary endothelium because pretreatment reverses an increase in serum angiotensin converting enzyme. Although not addressed in the present investigation, possible mechanisms for the potentiating effect of endotoxin on paraquat-induced lethality may involve superoxide anion generation, superoxide dismutase inhibition or both.
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PMID:Potentiation of paraquat lethality in mice by bacterial lipopolysaccharide pretreatment. 608 82

Angiotensin converting enzyme (ACE;EC 3.4.15.1), or kininase II, was studied in serum, cultured endothelial cells from cord artery, in macrophages of humans, and in serum and purified plasma membranes of rats following treatment with inducers of ACE biosynthesis. ACE activity was measured in biological fluids with an enzyme kinetic method employing synthetic 1-hipp-1-his-l-leu tripeptide as a substrate, and with a new method using 125I-labelled specific inhibitor of ACE as a sensitive probe for ACE binding sites. The latter technique also proved suitable for the quantification of ACE in cells. Anti-human ACE antibody was employed for immunofluorescence studies in human cells. Dexamethasone treatment caused an increase in ACE in cultured human endothelial cells, macrophages and in rat pulmonary plasma membranes, but failed to increase serum ACE activity in rats. Captopril and enalapril treatment of hypertensive patients increased total serum ACE, the increase being evident after removal of the active drug from the serum by prolonged storage or chloramine T treatment (captopril) or by dialysis (enalapril). Captopril increased the ACE content of endothelial cells and macrophages. Macrophages appeared sensitive to captopril induction of ACE biosynthesis after pre-stimulation with Escherichia coli lipopolysaccharide. Dexamethasone treatment potentiated the known induction of ACE in rat pulmonary tissue. Thus ACE biosynthesis may be enhanced by three categories of treatment: (1) glucocorticoid; (2) macrophage activation; (3) ACE inhibitors. The precise mechanism of ACE induction and its possible biological relevance await further clarification.
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PMID:Regulation of angiotensin converting enzyme. 610 Jun 6

The inhibitors of angiotensin converting enzyme (ACE), captopril and enalapril, were found to increase ACE concentration in cultured human endothelial cells from cord artery as measured with a novel ACE assay employing MK 351A, an inhibitor of ACE, and with immunofluorescense labeling using anti-human lung ACE antibody. Dexamethasone (10 nM) also increased ACE and potentiated the increase of cellular ACE caused by captopril. Similar effects of ACE inhibitors were seen in cultured human macrophages, particularly after prestimulation with E. coli lipopolysaccharide. In Wistar Kyoto rats, captopril caused a 3-fold increase of serum ACE, while dexamethasone (40 ug/day, 14 days) did not increase serum ACE. Combined treatment with captopril and dexamethasone caused a 5-fold increase of ACE in purified lung plasma membranes. ACE inhibitors induce increased ACE biosynthesis in endothelial cells, and in macrophages. The rise of cellular ACE with ACE inhibitors is potentiated by glucocorticoid.
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PMID:The induction of angiotensin converting enzyme by its inhibitors. 631 71

There is a renewed interest in the kininase I pathway of kinin metabolism, because des-Arg9-bradykinin (des-Arg9-BK) and des-Arg10-Lys-BK are selective and potent agonists of the B1 receptors, that are apparently upregulated by tissue injury. We have developed a polyclonal rabbit antiserum against des-Arg10-Lys-BK. In a radioimmunoassay for des-Arg10-Lys-BK, this antiserum exhibited high specificity. Notably, native kinins with the C-terminal Arg residue, bradykinin (BK) and Lys-BK, did not cross-react to a significant extent, whereas des-Arg9-BK and digoxigenin (DIG)-des-Arg9-BK exhibited a complete cross-reactivity. The antibodies were used to set up a sensitive chemiluminescence enzyme immunoassay (CLEIA) using the DIG-anti-DIG system as intermediate for the revelation of the immune complexes. The detection limit and the half-maximal saturation concentration for des-Arg9-BK were 27 and 1530 fmol/ml respectively. This assay, as well as another for BK quantification, have been applied in vitro to rabbit plasma activated by kaolin. The conversion of BK into des-Arg9-BK was generally efficient, and the persistence and concentration of both peptides were increased in the presence of enalaprilat an inhibitor of the angiotensin converting enzyme (ACEI). Rabbits treated with bacterial lipopolysaccharide exhibited an increase of plasma immunoreactive des-Arg9-BK that was potentiated in animals also treated with ACEI. This CLEIA for des-Arg9-BK is a new analytical tool applicable to analyze of the kininase I metabolites of kinins in vitro and in vivo. Measurements of des-Arg9-BK may be useful indicators of the kallikrein-kinin system activation.
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PMID:Quantification of des-Arg9-bradykinin using a chemiluminescence enzyme immunoassay: application to its kinetic profile during plasma activation. 771 39

Previous studies in adult animals have indicated that plasma angiotensin converting enzyme (ACE) activity is inhibited by endotoxin. Reduced ACE activity may decrease plasma angiotensin II (AII) levels, contributing to the refractory hypotension we have previously reported in neonatal septic shock. In this study, hemodynamic function, plasma renin activity (PRA), AII, prostacyclin (PGI2), and thromboxane B2 (TxB2) levels were measured in 17-20-day-old dogs before and 1, 2, and 3 hr after endotoxin administration (1 mg/kg, Escherichia coli lipopolysaccharide-B). PRA and AII levels rose significantly 60 min post-endotoxin, returning to baseline values by 180 min; PGI2 and thromboxane B2 levels rose post-endotoxin and remained elevated. Indomethacin or captopril was given by oral gavage 30-35 min before endotoxin. Captopril significantly blunted the rise in PRA and AII, while indomethacin blocked the rise in PGI2 and TxB2. Mean arterial blood pressure and cardiac output fell 60 min after endotoxin challenge without pharmacologic intervention and remained depressed. Our data suggest that renin and AII responses to endotoxin challenge remain intact in the neonatal subject. Maintenance of hemodynamics in indomethacin-pretreated dogs may be due to unopposed stimulation of the peripheral vasculature by AII. Thromboxane B2 in maintenance of vasomotor tone may be minimal in the young.
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PMID:Role of angiotensin II in neonatal sepsis. 850 19

The mechanism by which bradykinin induces catecholamine release from neural tissues was investigated in two experimental models of rat origin. The rat phaeochromocytoma cell line PC12 was used to identify the subtype of bradykinin receptors involved in the stimulation of noradrenaline secretion and to compare the effects of three different B2-antagonists. An increase of catecholamine release induced by bradykinin in vivo could be confirmed by measuring plasma levels in pithed spontaneously hypertensive rats (SHR) during electric preganglionic stimulation of the spinal cord. In this whole animal model, the effects of inhibition of both uptake and alpha 2-adrenoceptors on plasma levels of noradrenaline and adrenaline were studied as well as the potentiation of exogenous bradykinin by inhibition of angiotensin I-converting enzyme and neutral endopeptidase. The receptor subtypes involved (i.e. B1 or B2) were characterized by application either of HOE 140 or desArg9-[Leu8]-bradykinin respectively. In PC12 cells bradykinin provoked a prominent increase of noradrenaline release at low concentrations (concentration required for 50% of the maximum response 1 nM), whereas the B1-agonist desArg9-bradykinin was only effective at concentrations higher than 30 microM. The effects of both kinins could be blocked by the B2-specific antagonist HOE 890307 which, like HOE 140, exerted no agonistic effect of its own. As has been shown in other neural cells, the B2-specific antagonist [Thi5,8, D-Phe7]-bradykinin only acted as a low-affinity agonist without any antagonistic effects. In experiments where the intention was to induce B1-receptor expression either by angiotensin I-converting enzyme inhibition or lipopolysaccharide application, no alteration of the secretory response of PC12 cells to bradykinin or desArg9-bradykinin could be shown. In pithed SHR, infusion of bradykinin (up to 1200 ng/min/kg) did not enhance stimulation-dependent release of noradrenaline or adrenaline. After pretreatment of the rats with ramipril bradykinin became effective and its effects were further potentiated by the concomitant application of phosphoramidon. B2-antagonism by HOE 140 abolished the bradykinin-induced release of noradrenaline and reduced the effect on plasma adrenaline. The B1-specific antagonist desArg9-[Leu8]-bradykinin was unable to diminish the stimulatory effects of bradykinin and instead brought about an increase of plasma adrenaline levels. In conclusion, bradykinin stimulates release of catecholamines from PC12 cells, peripheral sympathetic neurons and chromaffine cells by activation of ganglionic or presynaptic B2-receptors. The adrenal medulla and PC12 cells appear to be highly susceptible not only to stimulation by bradykinin, but also to non-specific stimulatory effects of certain kinin-antagonists.
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PMID:Bradykinin increases catecholamine release via B2 receptors. 899 50


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