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Volumn 77, Issue , 2014, Pages 183-194

Binge alcohol promotes hypoxic liver injury through a CYP2E1-HIF-1α-dependent apoptosis pathway in mice and humans

Author keywords

Alcohol metabolizing enzymes; Apoptosis; Binge ethanol; CYP2E1; Free radicals; Human liver injury; Hypoxia; Protein nitration

Indexed keywords

3 NITROTYROSINE; 4 [BIS(2 CHLOROETHYL)OXIDOAMINO]PHENYLALANINE; CYTOCHROME P450 2E1; DNA NUCLEOTIDYLEXOTRANSFERASE; HYPOXIA INDUCIBLE FACTOR 1ALPHA; INDUCIBLE NITRIC OXIDE SYNTHASE; PROTEIN BNIP3; PROTEIN P53; ALCOHOL; HIF1A PROTEIN, HUMAN;

EID: 84908311556     PISSN: 08915849     EISSN: 18734596     Source Type: Journal    
DOI: 10.1016/j.freeradbiomed.2014.08.030     Document Type: Article
Times cited : (45)

References (55)
  • 1
    • 0024593463 scopus 로고
    • Incomplete compensation of enhanced hepatic oxygen consumption in rats with alcoholic centrilobular liver necrosis
    • H. Tsukamoto, and X.P. Xi Incomplete compensation of enhanced hepatic oxygen consumption in rats with alcoholic centrilobular liver necrosis Hepatology 9 1989 302 306
    • (1989) Hepatology , vol.9 , pp. 302-306
    • Tsukamoto, H.1    Xi, X.P.2
  • 3
    • 84875160269 scopus 로고    scopus 로고
    • Mouse model of chronic and binge ethanol feeding (the NIAAA model)
    • A. Bertola, S. Mathews, S.H. Ki, H. Wang, and B. Gao Mouse model of chronic and binge ethanol feeding (the NIAAA model) Nat. Protoc. 8 2013 627 637
    • (2013) Nat. Protoc. , vol.8 , pp. 627-637
    • Bertola, A.1    Mathews, S.2    Ki, S.H.3    Wang, H.4    Gao, B.5
  • 4
    • 0034847310 scopus 로고    scopus 로고
    • Alcoholic liver disease: New insights into mechanisms and preventative strategies
    • S. Stewart, D. Jones, and C.P. Day Alcoholic liver disease: new insights into mechanisms and preventative strategies Trends Mol. Med. 7 2001 408 413
    • (2001) Trends Mol. Med. , vol.7 , pp. 408-413
    • Stewart, S.1    Jones, D.2    Day, C.P.3
  • 6
    • 84879883093 scopus 로고    scopus 로고
    • National Institute on Alcohol Abuse and Alcoholism NIAAA Rockville, MD
    • National Institute on Alcohol Abuse and Alcoholism Moderate & binge drinking 2012 NIAAA Rockville, MD
    • (2012) Moderate & Binge Drinking
  • 7
    • 84856492849 scopus 로고    scopus 로고
    • Management of alcoholic hepatitis
    • P. Mathurin, and M.R. Lucey Management of alcoholic hepatitis J. Hepatol. 56 2012 S39 S45
    • (2012) J. Hepatol. , vol.56 , pp. 39-S45
    • Mathurin, P.1    Lucey, M.R.2
  • 8
    • 66349105670 scopus 로고    scopus 로고
    • Effect of binge drinking on the liver: An alarming public health issue?
    • P. Mathurin, and P. Deltenre Effect of binge drinking on the liver: an alarming public health issue? Gut 58 2009 613 617
    • (2009) Gut , vol.58 , pp. 613-617
    • Mathurin, P.1    Deltenre, P.2
  • 9
    • 70549092785 scopus 로고    scopus 로고
    • Mitochondrial reactive oxygen species regulate hypoxic signaling
    • R.B. Hamanaka, and N.S. Chandel Mitochondrial reactive oxygen species regulate hypoxic signaling Curr. Opin. Cell Biol. 21 2009 894 899
    • (2009) Curr. Opin. Cell Biol. , vol.21 , pp. 894-899
    • Hamanaka, R.B.1    Chandel, N.S.2
  • 10
    • 4944246547 scopus 로고    scopus 로고
    • The role of hypoxia inducible factor 1 (HIF-1) in hypoxia induced apoptosis
    • A.E. Greijer, and E. van der Wall The role of hypoxia inducible factor 1 (HIF-1) in hypoxia induced apoptosis J. Clin. Pathol. 57 2004 1009 1014
    • (2004) J. Clin. Pathol. , vol.57 , pp. 1009-1014
    • Greijer, A.E.1    Van Der Wall, E.2
  • 12
    • 84884899533 scopus 로고    scopus 로고
    • Cytochrome P450 2E1 potentiates ethanol induction of hypoxia and HIF-1α in vivo
    • X. Wang, D. Wu, L. Yang, L. Gan, and A.I. Cederbaum Cytochrome P450 2E1 potentiates ethanol induction of hypoxia and HIF-1α in vivo Free Radic. Biol. Med. 63 2013 175 186
    • (2013) Free Radic. Biol. Med. , vol.63 , pp. 175-186
    • Wang, X.1    Wu, D.2    Yang, L.3    Gan, L.4    Cederbaum, A.I.5
  • 13
    • 37249092151 scopus 로고    scopus 로고
    • Inducible nitric oxide synthase mediates hypoxia-induced hypoxia-inducible factor-1 alpha activation and vascular endothelial growth factor expression in oxygen-induced retinopathy
    • T. He, M. Ai, X.H. Zhao, and Y.Q. Xing Inducible nitric oxide synthase mediates hypoxia-induced hypoxia-inducible factor-1 alpha activation and vascular endothelial growth factor expression in oxygen-induced retinopathy Pathobiology 74 2007 336 343
    • (2007) Pathobiology , vol.74 , pp. 336-343
    • He, T.1    Ai, M.2    Zhao, X.H.3    Xing, Y.Q.4
  • 14
    • 80255134510 scopus 로고    scopus 로고
    • Oxygen-dependent regulation of nitric oxide production by inducible nitric oxide synthase
    • M.A. Robinson, J.E. Baumgardner, and C.M. Otto Oxygen-dependent regulation of nitric oxide production by inducible nitric oxide synthase Free Radic. Biol. Med. 51 2011 1952 1965
    • (2011) Free Radic. Biol. Med. , vol.51 , pp. 1952-1965
    • Robinson, M.A.1    Baumgardner, J.E.2    Otto, C.M.3
  • 15
    • 14844304367 scopus 로고    scopus 로고
    • Metabolism of alcohol
    • C.S. Lieber Metabolism of alcohol Clin. Liver Dis 9 2005 1 35
    • (2005) Clin. Liver Dis , vol.9 , pp. 1-35
    • Lieber, C.S.1
  • 18
    • 0029781891 scopus 로고    scopus 로고
    • Acute alcohol produces hypoxia directly in rat liver tissue in vivo: Role of Kupffer cells
    • G.E. Arteel, J.A. Raleigh, B.U. Bradford, and R.G. Thurman Acute alcohol produces hypoxia directly in rat liver tissue in vivo: role of Kupffer cells Am. J. Physiol. 271 1996 G494 G500
    • (1996) Am. J. Physiol. , vol.271 , pp. 494-G500
    • Arteel, G.E.1    Raleigh, J.A.2    Bradford, B.U.3    Thurman, R.G.4
  • 20
    • 84874752310 scopus 로고    scopus 로고
    • Selective inhibition of hypoxia-inducible factor 1α ameliorates adipose tissue dysfunction
    • K. Sun, N. Halberg, M. Khan, U.J. Magalang, and P.E. Scherer Selective inhibition of hypoxia-inducible factor 1α ameliorates adipose tissue dysfunction Mol. Cell. Biol. 33 2013 904 917
    • (2013) Mol. Cell. Biol. , vol.33 , pp. 904-917
    • Sun, K.1    Halberg, N.2    Khan, M.3    Magalang, U.J.4    Scherer, P.E.5
  • 22
    • 77956219883 scopus 로고    scopus 로고
    • A simple method to systematically study oxidatively modified proteins in biological samples and its applications
    • B.J. Song, S.K. Suh, and K.H. Moon A simple method to systematically study oxidatively modified proteins in biological samples and its applications Methods Enzymol. 473 2010 251 264
    • (2010) Methods Enzymol. , vol.473 , pp. 251-264
    • Song, B.J.1    Suh, S.K.2    Moon, K.H.3
  • 23
    • 0022117289 scopus 로고
    • P-Nitrophenol hydroxylation: A microsomal oxidation which is highly inducible by ethanol
    • L.A. Reinke, and M.J. Moyer p-Nitrophenol hydroxylation: a microsomal oxidation which is highly inducible by ethanol Drug Metab. Dispos. 13 1985 548 552
    • (1985) Drug Metab. Dispos. , vol.13 , pp. 548-552
    • Reinke, L.A.1    Moyer, M.J.2
  • 24
    • 84866421262 scopus 로고    scopus 로고
    • Critical role of cytochrome P450 2E1 (CYP2E1) in the development of high fat-induced non-alcoholic steatohepatitis
    • M.A. Abdelmegeed, A. Banerjee, S.H. Yoo, S. Jang, F.J. Gonzalez, and B.J. Song Critical role of cytochrome P450 2E1 (CYP2E1) in the development of high fat-induced non-alcoholic steatohepatitis J. Hepatol. 57 2012 860 866
    • (2012) J. Hepatol. , vol.57 , pp. 860-866
    • Abdelmegeed, M.A.1    Banerjee, A.2    Yoo, S.H.3    Jang, S.4    Gonzalez, F.J.5    Song, B.J.6
  • 26
    • 2642542967 scopus 로고    scopus 로고
    • Endogenous 2-oxoacids differentially regulate expression of oxygen sensors
    • C.L. Dalgard, H. Lu, A. Mohyeldin, and A. Verma Endogenous 2-oxoacids differentially regulate expression of oxygen sensors Biochem. J. 380 2004 419 424
    • (2004) Biochem. J. , vol.380 , pp. 419-424
    • Dalgard, C.L.1    Lu, H.2    Mohyeldin, A.3    Verma, A.4
  • 27
    • 0035855668 scopus 로고    scopus 로고
    • Dephosphorylated hypoxia-inducible factor 1alpha as a mediator of p53-dependent apoptosis during hypoxia
    • H. Suzuki, A. Tomida, and T. Tsuruo Dephosphorylated hypoxia-inducible factor 1alpha as a mediator of p53-dependent apoptosis during hypoxia Oncogene 20 2001 5779 5788
    • (2001) Oncogene , vol.20 , pp. 5779-5788
    • Suzuki, H.1    Tomida, A.2    Tsuruo, T.3
  • 28
    • 0029041124 scopus 로고
    • Hypoxia potentiates nitric oxide synthesis and transiently increases cytosolic calcium levels in pulmonary artery endothelial cells
    • V. Hampl, D.N. Cornfield, N.J. Cowan, and S.L. Archer Hypoxia potentiates nitric oxide synthesis and transiently increases cytosolic calcium levels in pulmonary artery endothelial cells Eur. Respir. J. 8 1995 515 522
    • (1995) Eur. Respir. J. , vol.8 , pp. 515-522
    • Hampl, V.1    Cornfield, D.N.2    Cowan, N.J.3    Archer, S.L.4
  • 30
    • 0038731081 scopus 로고    scopus 로고
    • Biological selectivity and functional aspects of protein tyrosine nitration
    • H. Ischiropoulos Biological selectivity and functional aspects of protein tyrosine nitration Biochem. Biophys. Res. Commun. 305 2003 776 783
    • (2003) Biochem. Biophys. Res. Commun. , vol.305 , pp. 776-783
    • Ischiropoulos, H.1
  • 31
    • 67650354415 scopus 로고    scopus 로고
    • Protein tyrosine nitration: Selectivity, physicochemical and biological consequences, denitration, and proteomics methods for the identification of tyrosine-nitrated proteins
    • N. Abello, H.A. Kerstjens, D.S. Postma, and R. Bischoff Protein tyrosine nitration: selectivity, physicochemical and biological consequences, denitration, and proteomics methods for the identification of tyrosine-nitrated proteins J. Proteome Res. 8 2009 3222 3238
    • (2009) J. Proteome Res. , vol.8 , pp. 3222-3238
    • Abello, N.1    Kerstjens, H.A.2    Postma, D.S.3    Bischoff, R.4
  • 33
    • 43949086592 scopus 로고    scopus 로고
    • Cytochrome P450 2E1 contributes to ethanol-induced fatty liver in mice
    • Y. Lu, J. Zhuge, X. Wang, J. Bai, and A.I. Cederbaum Cytochrome P450 2E1 contributes to ethanol-induced fatty liver in mice Hepatology 47 2008 1483 1494
    • (2008) Hepatology , vol.47 , pp. 1483-1494
    • Lu, Y.1    Zhuge, J.2    Wang, X.3    Bai, J.4    Cederbaum, A.I.5
  • 34
    • 39149123560 scopus 로고    scopus 로고
    • CYP2E1 and oxidative liver injury by alcohol
    • Y. Lu, and A.I. Cederbaum CYP2E1 and oxidative liver injury by alcohol Free Radic. Biol. Med. 44 2008 723 738
    • (2008) Free Radic. Biol. Med. , vol.44 , pp. 723-738
    • Lu, Y.1    Cederbaum, A.I.2
  • 35
    • 0030045690 scopus 로고    scopus 로고
    • Role of cytochrome P4502E1-dependent formation of hydroxyethyl free radical in the development of liver damage in rats intragastrically fed with ethanol
    • E. Albano, P. Clot, M. Morimoto, A. Tomasi, M. Ingelman-Sundberg, and S.W. French Role of cytochrome P4502E1-dependent formation of hydroxyethyl free radical in the development of liver damage in rats intragastrically fed with ethanol Hepatology 23 1996 155 163
    • (1996) Hepatology , vol.23 , pp. 155-163
    • Albano, E.1    Clot, P.2    Morimoto, M.3    Tomasi, A.4    Ingelman-Sundberg, M.5    French, S.W.6
  • 37
    • 0028641564 scopus 로고
    • Induction of CYP2E1 in liver, kidney, brain and intestine during chronic ethanol administration and withdrawal: Evidence that CYP2E1 possesses a rapid phase half-life of 6 hours or less
    • B.J. Roberts, S.E. Shoaf, K.S. Jeong, and B.J. Song Induction of CYP2E1 in liver, kidney, brain and intestine during chronic ethanol administration and withdrawal: evidence that CYP2E1 possesses a rapid phase half-life of 6 hours or less Biochem. Biophys. Res. Commun. 205 1994 1064 1071
    • (1994) Biochem. Biophys. Res. Commun. , vol.205 , pp. 1064-1071
    • Roberts, B.J.1    Shoaf, S.E.2    Jeong, K.S.3    Song, B.J.4
  • 38
    • 0028934858 scopus 로고
    • Effect of propylthiouracil treatment on NADPH-cytochrome P450 reductase levels, oxygen consumption and hydroxyl radical formation in liver microsomes from rats fed ethanol or acetone chronically
    • A.D. Ross, G. Varghese, B. Oporto, F.J. Carmichael, and Y. Israel Effect of propylthiouracil treatment on NADPH-cytochrome P450 reductase levels, oxygen consumption and hydroxyl radical formation in liver microsomes from rats fed ethanol or acetone chronically Biochem. Pharmacol. 49 1995 979 989
    • (1995) Biochem. Pharmacol. , vol.49 , pp. 979-989
    • Ross, A.D.1    Varghese, G.2    Oporto, B.3    Carmichael, F.J.4    Israel, Y.5
  • 39
    • 2442647948 scopus 로고    scopus 로고
    • The role of hypoxia in the pathogenesis of alcoholic liver disease
    • S.W. French The role of hypoxia in the pathogenesis of alcoholic liver disease Hepatol. Res. 29 2004 69 74
    • (2004) Hepatol. Res. , vol.29 , pp. 69-74
    • French, S.W.1
  • 40
    • 0023743930 scopus 로고
    • An increase of collagen biosynthesis precedes other symptoms of ethanol-induced liver damage in rats
    • A. Pawlicka, E. Bańkowski, L. Chrostek, and M. Szmitkowski An increase of collagen biosynthesis precedes other symptoms of ethanol-induced liver damage in rats Drug Alcohol Depend. 22 1988 113 116
    • (1988) Drug Alcohol Depend. , vol.22 , pp. 113-116
    • Pawlicka, A.1    Bańkowski, E.2    Chrostek, L.3    Szmitkowski, M.4
  • 41
    • 0025180766 scopus 로고
    • Increase in lipoperoxide and prolyl hydroxylase activity in rat liver following chronic ethanol feeding
    • S. Yamada, M. Yamada, Y. Murawaki, and C. Hirayama Increase in lipoperoxide and prolyl hydroxylase activity in rat liver following chronic ethanol feeding Biochem. Pharmacol. 40 1990 1015 1019
    • (1990) Biochem. Pharmacol. , vol.40 , pp. 1015-1019
    • Yamada, S.1    Yamada, M.2    Murawaki, Y.3    Hirayama, C.4
  • 42
    • 0026733683 scopus 로고
    • Influence of dietary zinc on hepatic collagen and prolyl hydroxylase activity in alcoholic rats
    • A. Giménez, J. Caballería, A. Parés, S. Alié, R. Deulofeu, H. Andreu, and J. Rodés Influence of dietary zinc on hepatic collagen and prolyl hydroxylase activity in alcoholic rats Hepatology 16 1992 815 819
    • (1992) Hepatology , vol.16 , pp. 815-819
    • Giménez, A.1    Caballería, J.2    Parés, A.3    Alié, S.4    Deulofeu, R.5    Andreu, H.6    Rodés, J.7
  • 43
    • 13844298275 scopus 로고    scopus 로고
    • The effect of ethanol-induced CYP2E1 on proteasome activity: The role of hydroxynonenal
    • F. Bardag-Gorce, J. Li, B.A. French, and S.W. French The effect of ethanol-induced CYP2E1 on proteasome activity: the role of hydroxynonenal Exp. Mol. Pathol. 78 2004 109 115
    • (2004) Exp. Mol. Pathol. , vol.78 , pp. 109-115
    • Bardag-Gorce, F.1    Li, J.2    French, B.A.3    French, S.W.4
  • 44
    • 2442676283 scopus 로고    scopus 로고
    • Hyperphosphorylation of rat liver proteasome subunits: The effects of ethanol and okadaic acid are compared
    • F. Bardag-Gorce, R. Venkatesh, J. Li, B.A. French, and S.W. French Hyperphosphorylation of rat liver proteasome subunits: the effects of ethanol and okadaic acid are compared Life Sci. 75 2004 585 597
    • (2004) Life Sci. , vol.75 , pp. 585-597
    • Bardag-Gorce, F.1    Venkatesh, R.2    Li, J.3    French, B.A.4    French, S.W.5
  • 45
    • 33644500142 scopus 로고    scopus 로고
    • Increased oxidation and degradation of cytosolic proteins in alcohol-exposed mouse liver and hepatoma cells
    • B.J. Kim, B.L. Hood, R.A. Aragon, J.P. Hardwick, T.P. Conrads, T.D. Veenstra, and B.J. Song Increased oxidation and degradation of cytosolic proteins in alcohol-exposed mouse liver and hepatoma cells Proteomics 6 2006 1250 1260
    • (2006) Proteomics , vol.6 , pp. 1250-1260
    • Kim, B.J.1    Hood, B.L.2    Aragon, R.A.3    Hardwick, J.P.4    Conrads, T.P.5    Veenstra, T.D.6    Song, B.J.7
  • 47
    • 84874525357 scopus 로고    scopus 로고
    • Suppression of the macrophage proteasome by ethanol impairs MHC class i antigen processing and presentation
    • A.J. D'Souza, S.D. Desai, X.L. Rudner, M.N. Kelly, S. Ruan, and J.E. Shellito Suppression of the macrophage proteasome by ethanol impairs MHC class I antigen processing and presentation PLoS One 8 2013 e56890
    • (2013) PLoS One , vol.8 , pp. 56890
    • D'Souza, A.J.1    Desai, S.D.2    Rudner, X.L.3    Kelly, M.N.4    Ruan, S.5    Shellito, J.E.6
  • 48
    • 77952412589 scopus 로고    scopus 로고
    • Effect of hypoxia-inducible factor 1-α on survivin in colorectal cancer
    • X.Y. Wu, Z.X. Fu, and X.H. Wang Effect of hypoxia-inducible factor 1-α on survivin in colorectal cancer Mol. Med. Rep 3 2010 409 415
    • (2010) Mol. Med. Rep , vol.3 , pp. 409-415
    • Wu, X.Y.1    Fu, Z.X.2    Wang, X.H.3
  • 49
    • 0042845994 scopus 로고    scopus 로고
    • Apoptosis-resistance of hypoxic cells: Multiple factors involved and a role for IAP-2
    • Z. Dong, J.Z. Wang, F. Yu, and M.A. Venkatachalam Apoptosis-resistance of hypoxic cells: multiple factors involved and a role for IAP-2 Am. J. Pathol. 163 2003 663 671
    • (2003) Am. J. Pathol. , vol.163 , pp. 663-671
    • Dong, Z.1    Wang, J.Z.2    Yu, F.3    Venkatachalam, M.A.4
  • 50
    • 0035418621 scopus 로고    scopus 로고
    • Constitutive expression of hypoxia-inducible factor-1alpha renders pancreatic cancer cells resistant to apoptosis induced by hypoxia and nutrient deprivation
    • N. Akakura, M. Kobayashi, I. Horiuchi, A. Suzuki, J. Wang, J. Chen, H. Niizeki, K. Kawamura, M. Hosokawa, and M. Asaka Constitutive expression of hypoxia-inducible factor-1alpha renders pancreatic cancer cells resistant to apoptosis induced by hypoxia and nutrient deprivation Cancer Res. 61 2001 6548 6554
    • (2001) Cancer Res. , vol.61 , pp. 6548-6554
    • Akakura, N.1    Kobayashi, M.2    Horiuchi, I.3    Suzuki, A.4    Wang, J.5    Chen, J.6    Niizeki, H.7    Kawamura, K.8    Hosokawa, M.9    Asaka, M.10
  • 51
    • 85012052650 scopus 로고    scopus 로고
    • Moderate, chronic ethanol feeding exacerbates carbon-tetrachloride-induced hepatic fibrosis via hepatocyte-specific hypoxia-inducible factor 1α
    • S. Roychowddhury, J.C. Chiang, M.R. McMullen, and L.E. Nagy Moderate, chronic ethanol feeding exacerbates carbon-tetrachloride-induced hepatic fibrosis via hepatocyte-specific hypoxia-inducible factor 1α Pharmacol. Res. Perspect 2 2014 e00061
    • (2014) Pharmacol. Res. Perspect , vol.2 , pp. 00061
    • Roychowddhury, S.1    Chiang, J.C.2    McMullen, M.R.3    Nagy, L.E.4
  • 53
    • 84875550946 scopus 로고    scopus 로고
    • Robust protein nitration contributes to acetaminophen-induced mitochondrial dysfunction and acute liver injury
    • M.A. Abdelmegeed, S. Jang, A. Banerjee, J.P. Hardwick, and B.J. Song Robust protein nitration contributes to acetaminophen-induced mitochondrial dysfunction and acute liver injury Free Radic. Biol. Med. 60 2013 211 222
    • (2013) Free Radic. Biol. Med. , vol.60 , pp. 211-222
    • Abdelmegeed, M.A.1    Jang, S.2    Banerjee, A.3    Hardwick, J.P.4    Song, B.J.5
  • 54
    • 33751003258 scopus 로고    scopus 로고
    • Inactivation of oxidized and S-nitrosylated mitochondrial proteins in alcoholic fatty liver of rats
    • K.H. Moon, B.L. Hood, B.J. Kim, J.P. Hardwick, T.P. Conrads, T.D. Veenstra, and B.J. Song Inactivation of oxidized and S-nitrosylated mitochondrial proteins in alcoholic fatty liver of rats Hepatology 44 2006 1218 1230
    • (2006) Hepatology , vol.44 , pp. 1218-1230
    • Moon, K.H.1    Hood, B.L.2    Kim, B.J.3    Hardwick, J.P.4    Conrads, T.P.5    Veenstra, T.D.6    Song, B.J.7
  • 55
    • 84872406355 scopus 로고    scopus 로고
    • CYP2E1 and oxidant stress in alcoholic and non-alcoholic fatty liver disease
    • T.M. Leung, and N. Nieto CYP2E1 and oxidant stress in alcoholic and non-alcoholic fatty liver disease J. Hepatol. 58 2013 395 398
    • (2013) J. Hepatol. , vol.58 , pp. 395-398
    • Leung, T.M.1    Nieto, N.2


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