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Brovkovych V, Dobrucki LW, Brovkovych S, Dobrucki I, Kalinowski L, Kiechle F, Malinski T. Nitric Oxide Measurements during Endotoxemia. Clin Chem 2001. [DOI: 10.1093/clinchem/47.6.1068] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Background: Excessive continuous NO release from inducible NO synthase over prolonged periods under pathological conditions, such as endotoxemia, contributes significantly to circulatory failure, hypotension, and septic shock. This NO production during endotoxemia is accompanied by superoxide release, which contributes to the fast decay of NO. Therefore, the amount of NO that diffuses to target sites may be much lower than the total amount released under pathological conditions.
Methods: We performed in vivo and ex vivo measurements of NO (electrochemical) and ex vivo in situ measurements of superoxide, peroxynitrite (chemiluminescence), and nitrite and nitrate (ultraviolet-visible spectroscopy). We determined the effect of lipopolysaccharide administration (20 mg/kg) on diffusible NO, total NO (diffusible plus consumed in chemical reactions), and superoxide and peroxynitrite release in the pulmonary arteries of rats.
Results: An increase in diffusible NO generated by constitutive NO synthase was observed immediately after administration of lipopolysaccharide, reaching a plateau (145 ± 18 nmol/L) after 540 ± 25 s. The plateau was followed by a decrease in NO concentration and its subsequent gradual increase after 45 min because of NO production by inducible NO synthase. The concentration of superoxide increased from 16 ± 2 nmol/L to 30 ± 3 nmol/L after 1 h and reached a plateau of 41 ± 4 nmol/L after 6 h. In contrast to the periodic changes in the concentration of diffusible NO, the total concentration of NO measured as a sum of nitrite and nitrate increased steadily during the entire period of endotoxemia, from 2.8 ± 0.2 μmol/L to 10 ± 1.8 μmol/L.
Conclusions: The direct measurement of NO concentrations in the rat pulmonary artery demonstrates dynamic changes throughout endotoxemia, which are related to the production of superoxide and the subsequent increase in peroxynitrite. Monitoring endotoxemia with total nitrate plus nitrite is not sensitive to these fluctuations in NO concentration.
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Affiliation(s)
- Viktor Brovkovych
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701
| | | | | | - Iwona Dobrucki
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701
| | | | - Frederick Kiechle
- Department of Clinical Pathology, William Beaumont Hospital, Royal Oak, MI 48073
| | - Tadeusz Malinski
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701
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Abstract
The gas NO is a messenger that modulates neuronal function. The use of NO donors and NO synthase inhibitors as pharmacological tools revealed that this free radical is probably implicated in the regulation of excitability and firing, in long-term potentiation and long-term depression, as well as in memory processes. Moreover, NO modulates neurotransmitter release. In vivo and in vitro studies have shown that, in all brain structures investigated, endogenous NO modulates the release of several neurotransmitters, such as acetylcholine, catecholamines, excitatory and inhibitory amino acids, serotonin, histamine, and adenosine. In most cases, enhanced NO level in the tissue increases the release of neurotransmitters, although decreasing effects have also been observed. Cyclic 3'-5' guanosine monophosphate and glutamate mediate the modulation of transmitter release by NO. Recent observations suggest that the release of some transmitters is dually influenced by NO. Thus, besides modulation by presynaptically located auto- and heteroreceptors, NO released from nitrergic neurons seems to play a universal role in modulating the release of transmitters in the brain.
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Affiliation(s)
- H Prast
- Institute of Pharmacy, Department of Pharmacology and Toxicology, University of Innsbruck, Peter-Mayr-Str. 1, A-6020 Innsbruck, Austria.
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Sorrenti V, Di Giacomo C, Salerno L, Siracusa MA, Guerrera F, Vanella A. Inhibition of neuronal nitric oxide synthase by N-phenacyl imidazoles. Nitric Oxide 2001; 5:32-8. [PMID: 11178934 DOI: 10.1006/niox.2000.0324] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) mediates a series of physiological processes, including regulation of vascular tone, macrofage-mediated neurotoxicity, platelet aggregation, learning and long-term potentiation, and neuronal transmission. Although NO mediates several physiological functions, overproduction of NO can be detrimental and play multiple roles in several pathological diseases. Accordingly, more potent inhibitors, more selective for neuronal nitric oxide synthase (nNOS) than endothelial NOS (eNOS) or inducible NOS (iNOS), could be useful in the treatment of cerebral ischemia and other neurodegenerative diseases. We recently described the synthesis of a series of imidazole derivatives. Among them N-(4-nitrophenacyl) imidazole (A) and N-(4-nitrophenacyl)-2-methyl-imidazole (B) were considered selective nNOS inhibitors. In the present study the action mechanism of compounds A and B was analyzed. Spectral changes observed in the presence of compound A indicate that this inhibitor exerts its effect without interaction with heme iron. Moreover compounds A and B, inhibit nNOS "noncompetitively" versus arginine, but "competitively" versus BH(4).
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Affiliation(s)
- V Sorrenti
- Department of Biological Chemistry, Medical Chemistry, and Molecular Biology, University of Catania, Italy
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Andric SA, Kostic TS, Koshimizu T, Stojilkovic SS. Dependence of soluble guanylyl cyclase activity on calcium signaling in pituitary cells. J Biol Chem 2001; 276:844-9. [PMID: 11031255 DOI: 10.1074/jbc.m004406200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The role of nitric oxide (NO) in the stimulation of soluble guanylyl cyclase (sGC) is well established, but the mechanism by which the enzyme is inactivated during the prolonged NO stimulation has not been characterized. In this paper we studied the interactions between NO and intracellular Ca(2+) in the control of sGC in rat anterior pituitary cells. Experiments were done in cultured cells, which expressed neuronal and endothelial NO synthases, and in cells with elevated NO levels induced by the expression of inducible NO synthase and by the addition of several NO donors. Basal sGC-dependent cGMP production was stimulated by the increase in NO levels in a time-dependent manner. In contrast, depolarization of cells by high K(+) and Bay K 8644, an L-type Ca(2+) channel agonist, inhibited sGC activity. Depolarization-induced down-regulation of sGC activity was also observed in cells with inhibited cGMP-dependent phosphodiesterases but not in cells bathed in Ca(2+)-deficient medium. This inhibition was independent from the pattern of Ca(2+) signaling (oscillatory versus nonoscillatory) and NO levels, and was determined by averaged concentration of intracellular Ca(2+). These results indicate that inactivation of sGC by intracellular Ca(2+) serves as a negative feedback to break the stimulatory action of NO on enzyme activity in intact pituitary cells.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Calcium/metabolism
- Calcium Channel Blockers/pharmacology
- Calcium Signaling/drug effects
- Cells, Cultured
- Cyclic AMP/metabolism
- Cyclic GMP/metabolism
- Dose-Response Relationship, Drug
- Female
- Guanidines/pharmacology
- Guanylate Cyclase/metabolism
- Isoenzymes/metabolism
- Nitric Oxide/metabolism
- Nitric Oxide Donors/pharmacology
- Nitric Oxide Synthase/antagonists & inhibitors
- Nitric Oxide Synthase/metabolism
- Nitroprusside/pharmacology
- Pituitary Gland, Anterior/cytology
- Pituitary Gland, Anterior/drug effects
- Pituitary Gland, Anterior/enzymology
- Pituitary Gland, Anterior/metabolism
- Potassium/pharmacology
- Rats
- Rats, Sprague-Dawley
- Solubility
- Vinca Alkaloids/pharmacology
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Affiliation(s)
- S A Andric
- Endocrinology and Reproduction Research Branch, NICHD, National Institutes of Health, Bethesda, Maryland 20892-4510, USA
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Calapai G, Marciano MC, Corica F, Allegra A, Parisi A, Frisina N, Caputi AP, Buemi M. Erythropoietin protects against brain ischemic injury by inhibition of nitric oxide formation. Eur J Pharmacol 2000; 401:349-56. [PMID: 10936493 DOI: 10.1016/s0014-2999(00)00466-0] [Citation(s) in RCA: 181] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Erythropoietin prevents in vitro glutamate-induced neuronal death and could play a role in the central nervous system. We investigated the in vivo effects of recombinant human erythropoietin after intraperitoneal (i.p.; 25-100 U) or intracerebroventricular (i.c.v.; 0.25-25 U) administration on survival, brain malonildialdehyde (MDA) levels, brain edema, hippocampal neuronal death and brain nitric oxide (NO) synthesis after bilateral carotid occlusion (5 min), followed by reperfusion in the Mongolian gerbil. Peripheral posttreatment with recombinant human erythropoietin reduced postischemic MDA levels, brain edema and increased survival. Either peripheral or i.c.v. posttreatment with recombinant human erythropoietin significantly reduced hippocampal CA1 neuronal loss, observed 7 days after the ischemic event. Increase of nitrite and nitrate (as an index of NO formation) in the hippocampus, as observed after ischemia, was reduced in animals treated with recombinant human erythropoietin. These data suggest that in vivo recombinant human erythropoietin effects on brain ischemic injury could be due to inhibition of NO overproduction.
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Affiliation(s)
- G Calapai
- Institute of Pharmacology, School of Medicine, Torre Biologica 5o piano - Policlinico Universitario, Via Consolare Valeria 49, I-98124, Messina, Italy.
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Chen CC, Lin YC, Chen SA, Luk HN, Ding PY, Chang MS, Chiang CE. Shortening of cardiac action potentials in endotoxic shock in guinea pigs is caused by an increase in nitric oxide activity and activation of the adenosine triphosphate-sensitive potassium channel. Crit Care Med 2000; 28:1713-20. [PMID: 10890608 DOI: 10.1097/00003246-200006000-00003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To investigate the roles of nitric oxide and adenosine triphosphate (ATP)-sensitive potassium channels (KATP) in the shortening of cardiac action potential in endotoxic shock. DESIGN Prospective animal study with concurrent controls. SETTING University animal research laboratory. SUBJECTS Adult Hartley guinea pigs, weighing 300-400 g. INTERVENTIONS Guinea pigs were anesthetized and mechanically ventilated for 6 hrs. Lipopolysaccharide (LPS) or saline (sham group) were given intravenously. Drug effects were examined at the end of 6 hrs. MEASUREMENTS AND MAIN RESULTS Plasma nitrate concentration was measured hourly, while guanosine 3',5'-cyclic monophosphate (cGMP) content and action potential duration at 90% of repolarization (APD90) of papillary muscle were examined every 2 hrs in the 6-hr endotoxemia in both the sham and the LPS-treated groups. The basal levels of these three variables showed no difference in the two groups. In the sham group, these variables did not change significantly (n = 14 for plasma nitrate determination; n = 5 for cGMP content measurement; n = 5-14 for APD90 measurement; all p > .05). But in the LPS-treated group, both plasma nitrate concentration and cGMP content of papillary muscle showed time-dependent increases and they were significantly higher than those in the sham group (at the 6th hr, plasma nitrate: 42.6 +/- 7.7 vs. 21.8 +/- 3.1 micromol/L, both n = 14, p < .01; cGMP: 1.52 +/- 0.15 vs. 0.73 +/- 0.08 pmol/mg protein, both n = 5, p < .01). In contrast, APD90 revealed a time-dependent decrease compared with that in the sham group (at the 6th hr, 137.1 +/- 52 vs. 188.2 +/- 4.8 msecs, both n = 14, p < .001). In the following 60-min in vitro recording of action potentials after the end of 6-hr endotoxemia, the shortened APD90 in the LPS-treated group did not recover and remained shorter compared with that in the sham group, in which the APD90 showed no significant changes (at the 60th min, 165.1 +/- 5.7 vs. 200.2 +/- 3.8 msecs, each n = 14, p < .01). However, in the presence of glibenclamide, a specific KATP blocker (100 micromol/L; n = 10), the APD90 could be reversed almost completely to the same value as that in the sham group (n = 14) (196.6 +/- 3.5 vs. 200.2 +/- 3.8 msecs; p > .05), despite glibenclamide having no effect on the APD90 in the sham group. In the LPS-treated group, NG-nitro-L-arginine methyl ester (1 mmol/L; n = 4), methylene blue (10 micromol/L; n = 5), and aminoguanidine (100 micromol/L; n = 4) significantly prolonged the shortened APD90 (192.5 +/- 3.1, 195.0 +/- 3.3, and 176.5 +/- 3.3 msecs, respectively; p < .01, p < .01, and p < .05, respectively, compared with that without these agents, 165.1 +/- 5.7 msecs, n = 14). These agents had negligible effects on the APD90 in the sham group (all p > .05). Furthermore, 8-bromoguanosine-3',5'-cyclic monophosphate (500 micromol/L; n = 5) decreased APD in intact papillary muscle (mean reduction of APD90, 13.5 +/- 3.5%, n = 5; p < .05), an effect abolished by pretreatment with glibenclamide (100 micromol/L; n = 5) that did not have an effect by itself. CONCLUSIONS In this experimental model, we provide reasonably convincing evidence to suggest that in endotoxic shock, an increase in nitric oxide activity may activate KATP, which plays a major role in the shortening of APD, presumably through a cGMP-dependent pathway.
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Affiliation(s)
- C C Chen
- Department of Medicine, Show Chwan Memorial Hospital, Chang-Hwa, Taiwan
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Abstract
Substances that increase intracellular calcium concentration ([Ca(2+)](i)), such as serotonin, are known to induce vascular smooth muscle (VSM) contraction. However, increases in [Ca(2+)](i) also activate Ca(2+)/calmodulin-dependent nitric oxide synthases (NOS), which leads to increases in cGMP and activation of cGMP-dependent protein kinase (PKG). One recently identified substrate protein of PKG is the small heat shock protein, HSP20. The purpose of this study was to determine if serotonin activates a Ca(2+)-dependent NOS in VSM. Strips of bovine carotid arterial smooth muscle denuded of endothelium were stimulated with serotonin in the presence and absence of the nonspecific NOS inhibitor N-monomethyl-L-arginine (L-NMMA). Activation of NOS was determined by increases in cGMP and in the phosphorylation of HSP20. Immunohistochemical and Western blotting techniques were performed to identify specific NOS isoforms in bovine carotid arterial smooth muscle preparations. Serotonin stimulation led to significant increases in cGMP and in the phosphorylation of HSP20, which were inhibited by pretreatment with L-NMMA. Antibodies against NOS 1 stained the media of bovine carotid and human renal arteries, whereas antibodies against NOS 3 stained only the endothelium. Additionally, the conversion of radiolabeled L-arginine to L-citrulline NOS activity demonstrated a consistent amount of activity present in the endothelium-denuded smooth muscle preparations that was reduced by 99% with an NOS 1 specific inhibitor. Finally, an NOS 1 specific inhibitor, 7-nitroindazole, augmented contractions induced by high extracellular KCl. This study demonstrates that NOS 1 is present in VSM and may effect physiological contractile responses.
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Affiliation(s)
- C M Brophy
- Departments of Surgery, Medical College of Georgia, Augusta, Georgia 30912, USA
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Abstract
Roles proposed for nitric oxide (NO) in CNS pathophysiology are increasingly diverse and range from intercellular signaling, through necrotic killing of cells and invading pathogens, to the involvement of NO in apoptosis and tissue remodeling. In vitro evidence and observations from experimental animal models of a variety of human neuropathologies, including stroke, indicate that glial cells can produce NO. Regulation of at least one of the NO synthase genes (NOS-2) in glia has been well described; however, apart from hints emerging out of co-culture studies and extrapolation based upon the reactivity of NO, we are a long way from identifying functions for glial-derived NO in the CNS. Although the assumption is that NO is very often cytotoxic, it is evident that NO production does not always equate with tissue damage, and that both the cellular source of NO and the timing of NO production are important factors in terms of its effects. With the development of strategies to transfer or manipulate expression of the NOS genes in specific cells in situ, the ability to deliver NO into the CNS via long-lived chemical donors, and the emergence of more selective NOS inhibitors, an appreciation of the significance of glial-derived NO will change.
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Affiliation(s)
- S Murphy
- Department of Pharmacology and the Neuroscience Program, University of Iowa College of Medicine, Iowa City, USA.
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Leber A, Hemmens B, Klösch B, Goessler W, Raber G, Mayer B, Schmidt K. Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. J Biol Chem 1999; 274:37658-64. [PMID: 10608822 DOI: 10.1074/jbc.274.53.37658] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human endothelial nitric-oxide synthase (eNOS) was expressed in the methylotrophic yeast Pichia pastoris, making use of the highly inducible alcohol oxidase promoter. The recombinant protein constituted approximately 3% of total protein and was largely soluble (>75%). About 1 mg of purified eNOS was obtained from 100-ml yeast cell cultures by affinity chromatography of crude cell supernatants. The purified enzyme had a V(max) of 192 +/- 18 nmol of L-citrulline x mg(-1) x min(-1), had a K(m) for L-arginine of 3.9 +/- 0.2 microM, and showed an absolute requirement for tetrahydrobiopterin (H(4)biopterin). NADPH oxidase activity was 136 +/- 9 and 342 +/- 24 nmol x mg(-1) x min(-1) in the absence and presence of 0.1 mM L-arginine, respectively, and not affected by H(4)biopterin. The protein contained 0.56 +/- 0.06 equivalents of FAD and 0.79 +/- 0.08 equivalents of FMN. On-line gel filtration/inductively coupled plasma mass spectrometry analysis confirmed that both iron (0.80 +/- 0.09 mol/subunit) and zinc (0.43 +/- 0.03 mol/subunit) were bound to the enzyme. Graphite furnace-atomic absorption spectroscopy yielded a value for bound iron of 0.84 +/- 0.04 mol/subunit. The absorbance of the enzyme at 398 nm implied a heme content of 0.85 +/- 0.09 mol/subunit, and the high pressure liquid chromatography heme assay gave an estimate of 0.71 +/- 0.02 mol heme/subunit. Gel permeation chromatography yielded one single peak with a Stokes radius of 6.62 +/- 0.7 nm, indicating that the native protein is dimeric. Upon low temperature gel electrophoresis the untreated protein appeared mainly as a monomer (88 +/- 3%), but pretreatment with H(4)biopterin and L-arginine led to a pronounced shift toward dimers (77 +/- 4%). Thus, in contrast to bovine eNOS (List, B. M., Klösch, B., Völker, C., Gorren, A. C. F., Sessa, W. C., Werner, E. R., Kukovetz, W. R., Schmidt, K., and Mayer, B. (1997) Biochem. J. 323, 159-165; Rodriguez-Crespo, I., Gerber, N. C., and Ortiz de Montellano, P. R. (1996) J. Biol. Chem. 271, 11462-11467), the human eNOS appears to be markedly stabilized by H(4)biopterin.
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Affiliation(s)
- A Leber
- Institut für Pharmakologie und Toxikologie, Karl-Franzens-Universität Graz, Universitätsplatz 2, Austria
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He K, Nukada H, McMorran PD, Murphy MP. Protein carbonyl formation and tyrosine nitration as markers of oxidative damage during ischaemia-reperfusion injury to rat sciatic nerve. Neuroscience 1999; 94:909-16. [PMID: 10579583 DOI: 10.1016/s0306-4522(99)00350-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have investigated the role of oxidative damage in peripheral nerve ischaemia-reperfusion injury using a rat sciatic nerve model. After 5 h ischaemia blood flow to the sciatic nerve was restarted and markers of oxidative damage measured after various times of reperfusion. As a marker of protein oxidative damage, protein carbonyl formation was measured using a sensitive enzyme-linked immunosorbent assay. Protein carbonyl content was unaffected by ischaemia alone, but increased by 55% after 12-18 h reperfusion, correlating with the onset of nerve pathology. Pretreatment with the xanthine oxidase inhibitor allopurinol prevented these abnormalities, suggesting that xanthine oxidase activity is proximal to oxidative damage during reperfusion injury. To determine whether formation of the potent oxidant peroxynitrite from nitric oxide and superoxide contributed to ischaemia-reperfusion injury, we measured the accumulation of 3-nitrotyrosine residues in proteins. Only one protein of 49,000 mol. wt contained significant amounts of 3-nitrotyrosine residues which was shown to be glial fibrillary acidic protein, an abundant cytoskeletal protein in Schwann cells. However glial fibrillary acidic protein contained 3-nitrotyrosine residues prior to ischaemia-reperfusion, and the amount of nitrated tyrosine residues in total glial fibrillary acidic protein did not increase significantly during reperfusion, therefore it was not possible to draw conclusions about the role of peroxynitrite in nerve reperfusion injury.
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Affiliation(s)
- K He
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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