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(Received for publication, January 29, 1996) From the
CYP2E1, a cytochrome P-450 that is well conserved across
mammalian species, metabolizes ethanol and many low molecular weight
toxins and cancer suspect agents. The cyp2e1 gene was
isolated, and a mouse line that lacks expression of CYP2E1 was
generated by homologous recombination in embryonic stem cells. Animals
deficient in expression of the enzyme were fertile, developed normally,
and exhibited no obvious phenotypic abnormalities, thus indicating that
CYP2E1 has no critical role in mammalian development and physiology in
the absence of external stimuli. When cyp2e1 knockout mice
were challenged with the common analgesic acetaminophen, they were
found to be considerably less sensitive to its hepatotoxic effects than
wild-type animals, indicating that this P-450 is the principal enzyme
responsible for the metabolic conversion of the drug to its active
hepatotoxic metabolite.
Cytochromes P-450 (P-450) ( CYP2E1 is the principal P-450
responsible for the metabolism of ethanol and is considered as a major
component of the microsomal ethanol-oxidizing
system(4, 5) . Among xenobiotics metabolized by CYP2E1
are acetaldehyde, acetaminophen, acrylamide, aniline, benzene, butanol,
carbon tetrachloride, diethylether, dimethyl sulfoxide, ethyl
carbamate, ethylene chloride, halothane, glycerol, ethylene glycol, N-nitrosodimethylamine, 4-nitrophenol, pyrazole, pyridine, and
vinyl chloride(6) . Many of these chemicals are known toxins,
established chemical carcinogens, or suspected carcinogens.
CYP2E1-mediated oxidation of a variety of substrates is also believed
to liberate a substantial amount of reactive oxygen that can lead to
membrane lipid peroxidation and cell toxicity(7) . CYP2E1 is
also capable of metabolizing endogenous chemicals including acetone and
acetol, which are key metabolites in the methylglyoxal and propanediol
pathways of gluconeogenesis(8, 9) . CYP2E1 can also
carry out the metabolism of arachidonic acid, resulting in the
production of several hydroxyeicosatetraenoic acids(10) , some
of which may have physiological and pharmacological
properties(11) . CYP2E1 is inducible by ethanol and other
low molecular weight substrates(5, 12) . This
induction is primarily due to a postranscriptional mechanism where
presence of the substrate stabilizes the enzyme from
degradation(13) . However, transcriptional mechanisms have not
been ruled out(14) . This enzyme is also induced by starvation
and in uncontrolled diabetes(15, 16) . P-450s have
been implicated in the hepatotoxicity of acetaminophen (also called
paracetamol), an over-the-counter analgesic and antipyretic that is
commonly used worldwide as a substitute for acetylsalicylic acid
(aspirin®) due to its lack of gastric ulceration and general low
toxicity when used within the recommended dose range (17, 18, 19) . Acetaminophen causes
hepatotoxicity at a low frequency. It is metabolized to N-acetyl-p-benzoquinoneimine, a metabolite that is
capable of reacting with cellular nucleophiles. The bulk of this
metabolite is either reduced back to acetaminophen or conjugated with
glutathione. It was postulated that toxicity results from low cellular
glutathione leaving an excess of active metabolite that can cause cell
toxicity(19, 20, 21, 22) . The
P-450s responsible for acetaminophen activation have been investigated.
Ethanol was reported to increase the toxicity of acetaminophen in
mice(20, 23) , thus suggesting the involvement of
CYP2E1 in vivo. In vitro studies have also implicated
human CYP1A2 in addition to CYP2E1 in acetaminophen metabolism,
although the latter P-450 had a lower K The conservation across
species in expression and catalytic activities of CYP2E1 and its
ability to metabolize and be induced by chemicals that are generated
endogenously, such as acetone and ethanol, suggests that it has an
important physiological role in mammals. To investigate this
possibility and to determine if this P-450 is involved in the
hepatotoxicities and carcinogenesis potential of many of its
substrates, mice lacking CYP2E1 expression were produced and
characterized.
Figure 1:
Panel A displays the
restriction map of the cyp2e1 gene, the targeting vector, and
the predicted homologous recombinant locus. The numbers over the horizontal double arrows are the predicted sizes of
restriction fragments in kb. Panel B shows a Southern blot of
the specific ES clone and wild-type ES cells, and panel C displays a Southern blot of a typical screen of tail clipping DNA
from mice with different genotypes. The sizes of the fragments are in
kb.
The
construct was made in six cloning steps (see Fig. 1A). 1) The HindIII site in the polylinker region of pGEM-3Z (Promega) was
destroyed by HindIII digestion, Klenow polymerase treatment,
and religation. 2) An 8-kb SalI-SmaI cyp2e1 genomic fragment was subcloned into the same sites in the modified
pGEM-3Z. 3) The plasmid made in step 2 was digested with HindIII, treated with Klenow polymerase, and ligated with XhoI linkers in order to remove the 1.8-kb fragment containing
exon 2 and add a restriction site compatible with the PGK-NEO cassette.
This 1.9-kb cassette was previously modified by changing the BamHI site at its 3` end to an XhoI site by use of
Klenow polymerase and XhoI linkers. 4) The XhoI
fragment containing the PGK-NEO cassette was subcloned into the cyp2e1 gene at the XhoI site. 5) The cyp2e1 construct, containing the PGK-NEO cassette was digested with AflII, treated with Klenow polymerase, and ligated with HindIII linkers. 6) The cyp2e1 gene was released from
this construct by digestion with SalI and HindIII and
inserted into the corresponding sites of pMC1TK plasmid (29) containing the herpes simplex virus thymidine kinase gene.
The resulting plasmid was used as a targeting vector.
Messenger RNA was analyzed by
Northern blots using liver RNA and the rat CYP2E1 cDNA as a probe.
Total RNA was isolated from liver tissue using guanidinium thiocyanate
extraction (40) and cesium trifluoroacetic acid centrifugation
as described previously(31) . Ten µg of total RNA was
subjected to electrophoresis on 1% agarose gels containing 2.2 M formaldehyde (41) and blotted to GeneScreen Plus (DuPont)
nylon membranes using 3 M NaCl and 0.15 M sodium
citrate, pH 7.0. The CYP2E1 cDNA was labeled using random primers and
[
Mice
homozygous for the disrupted allele, designated
cyp2e1
Figure 2:
Western
immunoblots of different P-450s in cyp2e1
The expression of CYP2E1 mRNA was also
analyzed in the cyp2e1
Figure 3:
Analysis of RNA in livers of
cyp2e1
Figure 4:
Survival rate of cyp2e1-/-
(
To determine the mechanism of
toxicity, levels of enzymes and other serum components, some of which
are diagnostic for liver and kidney injury, were measured in serum of
treated mice that survived in the experiments described above. At all
doses, levels of creatinine, bilirubin, and alkaline phosphatase were
within the normal range for mice and were not significantly different
between the cyp2e1
Figure 5:
Determinations of aspartate
aminotransferase (panel A) and alanine aminotransferase (panel B) activities in serum of cyp2e1
The present study using mice lacking expression of CYP2E1
establish that although this P-450 is highly conserved in mammals, it
does not appear to play a significant role in development, reproductive
vitality, and physiology. Under conditions of exposure to certain
chemicals, CYP2E1 accentuates toxicity. Efforts are underway to use
this animal model to determine whether this enzyme is responsible for
the carcinogenicity of a number of its chemical substrates including N-nitrosodimethylamine and phenacetin. CYP2E1 may also
exert a role in alcoholic liver disease. Lipid peroxidation was found
to be associated with alcoholic liver injury in humans and experiment
animals(42) . This could be the result, in part, of increased
oxygen radical production by ethanol-induced CYP2E1(7) . The
cyp2e1 During fasting and diabetic ketosis, serum acetone,
acetol, and 1,2-propanediol are elevated. CYP2E1 is concommitantly
induced due to protein stabilization by acetone(16) . Acetone
is primarily oxidized to acetol by CYP2E1. Acetol is further
metabolized to 1,2-propanediol by the same P-450 in a pathway of
gluconeogenesis, suggesting a physiological role for this P-450 during
pathophysiological and dietary stress(8) . The
cyp2e1
Volume 271,
Number 20,
Issue of May 17, 1996 pp. 12063-12067
©1996 by The American Society for Biochemistry and Molecular Biology, Inc.
)are a superfamily of
hemoproteins that carry out oxidative metabolism of many endogenous and
foreign chemicals(1) . In mammals, P-450s can be functionally
segregated into two groups, those that participate in biochemical
pathways leading to the synthesis of steroid hormones and those that
primarily metabolize foreign chemicals or xenobiotics such as drugs.
The latter enzymes are included in the CYP1, CYP2, CYP3, and CYP4
families(2) . Many of the hepatic xenobiotic-metabolizing
P-450s also metabolize endogenous compounds, but the significance of
these reactions is questionable. A clue to the lack of a critical role
for many of the P-450s, particularly those in family 2, in development,
reproduction, and longevity, is the marked species differences in their
expression and catalytic activities(3) . However, some of the
xenobiotic-metabolizing P-450s are well conserved, including those in
the CYP1 family and CYP2E1, suggesting that they may perform an
important physiological function.
than CYP1A2(24, 25) .
Construction of the Targeting Vector
Genomic
clones corresponding to cyp2e1 were obtained by screening a
129/SV genomic library (Strategene) with a rat CYP2E1
cDNA(26) . A clone spanning 14.2 kb and containing all nine
exons of the gene was subcloned as a SalI fragment. To disrupt
the gene, a 1.9-kb HindIII fragment containing exon 2 and
spanning from intron 1 to intron 2 was deleted and replaced with the
bacterial phosphoribosyltransferase II gene, under control of the
phosphoglycerate kinase-1 promoter (PGK-NEO), that confers resistance
to the neomycin derivative G418 (Life Sciences Inc.). This gene was
derived from the plasmid pPNT(27) . The PGK-NEO cassette was
inserted in the same transcriptional orientation as the cyp2e1 gene. The herpes simplex virus thymidine kinase gene was inserted
at the 3` end of the cyp2e1 gene as a negative selection
against random integration of the construct(28) . The construct
used for targeting (see Fig. 1A), contained 2.3 kb of
5` and 3.6 kb of 3` genomic DNA flanking the PGK-NEO cassette.
Production of Chimeric Mice
The plasmid DNA used
for targeting was purified by banding twice on cesium chloride. After
linearization with HindIII, 40 µg was electroporated into
J1 embryonic stem (ES) cells (30) using conditions described
previously (31) . ES cell clones resistant to both G418 and
ganciclovir (gift of Syntex) were selected and screened for homologous
recombination, and clones having the expected Southern blot pattern for
a homologous recombinant (see below) were regrown and injected into
C57BL/6N blastocysts. The blastocysts were transferred into the uterus
of a pseudopregnant recipient NIH Swiss mouse in order to produce an
animal exhibiting chimerism(32) . Male chimeras presenting
greater than 95% 129/SV contribution, as determined by coat color, were
bred with C57BL/6N females to determine if the trait was transmitted to
the germ line. Southern blot genotyping performed on DNA extracted from
tail clips, was used to score for the presence of the mutated cyp2e1 gene in the progeny. Homozygotes were produced by
crossing the F1 generation.Genotyping of ES Cells and Mice
DNA was isolated
from ES cells and mouse tail clips as described previously (33) and digested with either BglII or SpeI.
The digested DNAs were subjected to electrophoresis in 0.6% agarose
gels and transferred to GeneScreen Plus nylon membranes (DuPont) using
0.4 N NaOH. The conditions for hybridization and washing were
described previously (31) . A 3`-flanking probe derived from a AflII-ClaI genomic fragment (see probe P5, Fig. 1A) was labeled with
[
P]dCTP using random primers. This probe
hybridizes with 5.9- and 3.2-kb BglII fragments and with a
6.3-kb SpeI diagnostic fragment for the wild-type cyp2e1 allele. The homologous recombinant allele generated fragments of
5.5 and 7.7 kb corresponding to digestions with BglII and SpeI, respectively (see Fig. 1, A-C).
Mice homozygous for the disrupted cyp2e1 allele were
designated cyp2e1
.Analysis of CYP2E1 Expression
Mice were killed by
carbon monoxide asphyxiation, and 400 mg of liver tissue was disrupted
using a Teflon-glass homogenizer in 3 ml of a buffer containing 20
mM Tris-HCl, pH 7.5, 1 mM EDTA, 25 mM KCl, 1
mM phenylmethylsulfonyl fluoride, 1 mM dithiothreitol, and 10% (v/v) glycerol. The homogenate was
centrifuged for 20 min at 10,000 
g, and the
supernatant was centrifuged for 12 min at 500,000 g in
a Beckman Optima TL tabletop ultracentrifuge to recover microsomes. All
operations were performed at 4 °C. The microsome pellets were
resuspended by homogenization in 0.1 M sodium potassium
phosphate buffer, pH 7.4, containing 20% (v/v) glycerol and stored at
-80 °C until use. Protein concentrations were determined with
the bichinchoninic acid reagent (Pierce) using bovine serum albumin as
a standard. SDS-polyacrylamide gel electrophoresis was carried out
according to Laemmli (34) using 10 µg of microsomal
protein. Proteins were electroblotted to nitrocellulose membranes by
semidry transfer. Immunoblotting was performed according to Towbin et al.(35) . Rabbit antibodies against
CYP1A2(36) , CYP2A1(37) , CYP2B1(38) , and
CYP3A1 (39) were produced as described earlier. Rabbit antisera
against CYP2C6 was produced by Dr. Kiyoshi Nagata (Tohoku University,
Sendai Japan). Antibody to CYP2E1, produced in goat, was obtained from
the Gentest Corp. The secondary antibodies, labeled with horseradish
peroxidase, were from Amersham Corp.P]dCTP. The conditions for prehybridization,
hybridization, and washing were described previously(31) .Acetaminophen Toxicity
The protocol for dosing
mice with acetaminophen was approved by the National Cancer
Institute's Animal Care and Use Committee (Protocol LMCE-023).
Male cyp2e1 and wild-type strains, from 2 to
4 months of age, were administered acetaminophen by intraperitoneal
injection at doses ranging from 0 to 800 mg/kg in alkaline saline
solution. Each dose group consisted of 10 mice. To score toxicities,
the number of surviving animals at 48 h were quantified. Two complete
and independent experiments were conducted over the same dose range.
From the remaining mice, blood was collected and serum was used to
determine the levels of bilirubin, creatinine, alkaline phosphatase,
aspartate aminotransferase, and alanine aminotransferase. These
measurements were performed by the Diagnostic Services and Clinical
Pathology Laboratory of the Uniformed Services University of the Health
Sciences Clinical Chemistry Department using a Kodac Ektachem 250
automated plasma analyzer.
Production and Characterization of the
cyp2e1
The cyp2e1 gene
was isolated from a 129/SV mouse genomic library. The genomic clone
spanned 14.2 kb and contained the complete coding region (Fig. 1A). The gene was disrupted by the replacement of
exon 2 with the PGK-NEO cassette. A diagnostic probe, designated probe
P5 and shown in Fig. 1A, was generated that detects
homologous integrations of the targeting construct into the gene. Mice
having the wild-type allele are expected to yield a 5.9-kb BglII and a 6.3-kb SpeI fragments. A typical
autoradiography of a Southern blot of DNA from the ES cell clone AY168
and control ES cells hybridized with the probe P5 is shown in Fig. 1B. Upon longer exposure of the blot, an expected
3.2-kb BglII fragment was also detected. Specific recombinants
had diagnostic 5.5- and 7.7-kb fragments from BglII and SpeI, respectively. Screening of mice generated by breeding
for heterozygotes for the disrupted cyp2e1 allele is shown in Fig. 1C. Heterozygous mice have the diagnostic
fragments corresponding to the wild-type and disrupted alleles, whereas
mice that have two copies of the disrupted allele yielded the 5.5- and
7.7-kb fragments after digestion with BglII and SpeI,
respectively. Hybridization with the PGK-NEO gene as a probe revealed
only a single hybridizing fragments of 2.3, 7.7, and 11.3 kb for the BglII-, SpeI-, and ApaI-digested DNA (data
not shown), demonstrating that this clone did not contain any
additional random integration of the targeting construct. Mice, were born normally and appeared
indistinguishable from their wild-type counterparts. No differences
were found between litter size and growth rates for the
cyp2e1 animals as compared with wild-type
littermate controls. The expression of CYP2E1 was determined by
immunoblotting with anti-rat CYP2E1 antibody. As expected, a complete
absence of protein expression was found in the livers of
cyp2e1 mice (Fig. 2). The liver is the
primary site of expression of this P-450(16) . P-450s in the
CYP1A, CYP2A, CYP2B, CYP2C, and CYP3A subfamilies were expressed in the
cyp2e1 mice at similar levels to those found
in control animals, thus indicating that the loss of CYP2E1 was not
compensated by an increase in expression of other P-450s, although it
remains a possibility that a P-450 not detected with our anti-rat P-450
antibodies is overexpressed.
mice. Each lane was loaded with 10 µg of microsomal protein
from a single mouse.
mice. Two transcripts
were detected in the liver of normal mice and mice heterozygous for the
disrupted allele (Fig. 3). In the cyp2e1 mice, neither of these two RNA transcripts were found. Instead,
two lower abundance RNAs slightly smaller than the transcripts present
in wild-type animals were detected. These may be transcripts from the
disrupted allele that should be smaller than a transcript from the
normal allele since exon 2 is deleted in the disrupted allele. The
lower abundance of these RNAs, as compared with those from the
wild-type allele, is not surprising since mRNAs that do not encode a
normal protein are usually not stable. In any case, the protein and RNA
establish with certainty that the cyp2e1 gene is not expressed
in the knockout animals. The change in size and abundance of the high
molecular weight transcript annealing with the CYP2E1 cDNA in the
cyp2e1 mice suggest that it is not due to a
cross-hybridizing mRNA derived from another gene but is most likely a
read-through transcript of the cyp2e1 gene with an alternate
polyadenylation signal.
mice. Each lane was loaded with 10
µg of total liver RNA from a single mouse. The blot was exposed for
24 h with aid of an intensifying screen.
Acetaminophen Toxicity
P-450s have been implicated
in the hepatotoxicity of acetaminophen. To determine whether CYP2E1
influences the toxicity of this compound in mice, the
cyp2e1 animals were administered the drug and
compared with wild-type mice. Survival curves indicated that the
cyp2e1 mice were more resistant to
acetaminophen toxicity than wild-type animals (Fig. 4). Levels
of 400 mg of acetaminophen/kg producing toxicity in wild-type mice in
this study were similar to those that produced toxicity in other
studies(20, 23) . Cyp2e1 mice survived at doses up to 400 mg/kg, whereas over 50% of
wild-type animals died at these doses.
) and wild-type (
) mice as a function of the dose of
acetaminophen administered. Groups of 10 mice were injected
intraperitoneally with acetaminophen in alkaline saline and survival
scored after 48 h. Two complete and independent experiments were
performed. The curves were manually fit to the data
points.
and wild-type mice. In
contrast, liver enzymes aspartate aminotransferase and alanine
aminotransferase were elevated at high doses of acetaminophen (Fig. 5). Elevation of these liver enzymes, which are considered
a measure of liver cell death, were detected at doses of 200 and 400
mg/kg in wild-type animals but were unchanged at these doses in the
cyp2e1 mice. These data indicate that liver
damage is involved in mediating the toxicity of acetaminophen. This was
confirmed by analysis of liver histology of acetaminophen-treated mice
(data not shown). At doses higher than 600 mg/kg, a significant level
of toxicity was also found in the cyp2e1 mice. These data suggest that CYP2E1 mediates the hepatotoxicity
of acetaminophen. Other P-450s such as CYP1A2 having a higher K
for acetaminophen may be responsible for the
toxicity in cyp2e1 mice at high doses of the
drug.
() and wild-type () mice as a function of the dose of
acetaminophen administered. The mean + standard deviations are
shown with n = 3 (* p < 0.05,** p < 0.01,*** p < 0.001). At the 600 mg/kg dose group
for the wild-type mice in panel B, two animals were
analyzed.
mice could be used to test this
possibility. mice should be of use to determine if
CYP2E1 plays an essential role in survival under conditions of
starvation.
)
©1996 by The American Society for Biochemistry and Molecular Biology, Inc.
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C. Cheung, A.-M. Yu, J. M. Ward, K. W. Krausz, T. E. Akiyama, L. Feigenbaum, and F. J. Gonzalez THE CYP2E1-HUMANIZED TRANSGENIC MOUSE: ROLE OF CYP2E1 IN ACETAMINOPHEN HEPATOTOXICITY Drug Metab. Dispos., March 1, 2005; 33(3): 449 - 457. [Abstract] [Full Text] [PDF]
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J. Gu, H. Cui, M. Behr, L. Zhang, Q.-Y. Zhang, W. Yang, J. A. Hinson, and X. Ding In Vivo Mechanisms of Tissue-Selective Drug Toxicity: Effects of Liver-Specific Knockout of the NADPH-Cytochrome P450 Reductase Gene on Acetaminophen Toxicity in Kidney, Lung, and Nasal Mucosa Mol. Pharmacol., March 1, 2005; 67(3): 623 - 630. [Abstract] [Full Text] [PDF]
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B.I. Ghanayem, K.L. Witt, L. El-Hadri, U. Hoffler, G.E. Kissling, M.D. Shelby, and J.B. Bishop Comparison of Germ Cell Mutagenicity in Male CYP2E1-Null and Wild-Type Mice Treated with Acrylamide: Evidence Supporting a Glycidamide-Mediated Effect Biol Reprod, January 1, 2005; 72(1): 157 - 163. [Abstract] [Full Text] [PDF]
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G. L. Guo, J. S. Moffit, C. J. Nicol, J. M. Ward, L. A. Aleksunes, A. L. Slitt, S. A. Kliewer, J. E. Manautou, and F. J. Gonzalez Enhanced Acetaminophen Toxicity by Activation of the Pregnane X Receptor Toxicol. Sci., December 1, 2004; 82(2): 374 - 380. [Abstract] [Full Text] [PDF]
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A. C. Simmonds, C. A. Reilly, R. M. Baldwin, B. I. Ghanayem, D. L. Lanza, G. S. Yost, K. S. Collins, and P.-G. Forkert BIOACTIVATION OF 1,1-DICHLOROETHYLENE TO ITS EPOXIDE BY CYP2E1 AND CYP2F ENZYMES Drug Metab. Dispos., September 1, 2004; 32(9): 1032 - 1039. [Abstract] [Full Text] [PDF]
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A. C. Simmonds, B. I. Ghanayem, A. Sharma, C. A. Reilly, B. Millen, G. S. Yost, and P.-G. Forkert Bioactivation of 1,1-Dichloroethylene by CYP2E1 and CYP2F2 in Murine Lung J. Pharmacol. Exp. Ther., September 1, 2004; 310(3): 855 - 864. [Abstract] [Full Text] [PDF]
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K. K. Wolf, S. G. Wood, J. L. Bement, P. R. Sinclair, S. A. Wrighton, E. Jeffery, F. J. Gonzalez, and J. F. Sinclair ROLE OF MOUSE CYP2E1 IN THE O-HYDROXYLATION OF P-NITROPHENOL: COMPARISON OF ACTIVITIES IN HEPATIC MICROSOMES FROM CYP2E1(-/-) AND WILD-TYPE MICE Drug Metab. Dispos., July 1, 2004; 32(7): 681 - 684. [Abstract] [Full Text] [PDF]
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J. L. Raucy, J. Lasker, K. Ozaki, and V. Zoleta Regulation of CYP2E1 by Ethanol and Palmitic Acid and CYP4A11 by Clofibrate in Primary Cultures of Human Hepatocytes Toxicol. Sci., June 1, 2004; 79(2): 233 - 241. [Abstract] [Full Text] [PDF]
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 C. J. Henderson and C. R. Wolf Transgenic Analysis of Human Drug-Metabolizing Enzymes: Preclinical Drug Development and Toxicology Mol. Interv., September 1, 2003; 3(6): 331 - 343. [Abstract] [Full Text] [PDF]
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K. S. Sugamori, S. Wong, A. Gaedigk, V. Yu, H. Abramovici, R. Rozmahel, and D. M. Grant Generation and Functional Characterization of Arylamine N-Acetyltransferase Nat1/Nat2Double-Knockout Mice Mol. Pharmacol., July 1, 2003; 64(1): 170 - 179. [Abstract] [Full Text] [PDF]
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L. H. Lash, R. N. Hines, F. J. Gonzalez, T. R. Zacharewski, and M. A. Rothstein Genetics and Susceptibility to Toxic Chemicals: Do You (or Should You) Know Your Genetic Profile? J. Pharmacol. Exp. Ther., May 1, 2003; 305(2): 403 - 409. [Abstract] [Full Text] [PDF]
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U. Hoffler, H. A. El-Masri, and B. I. Ghanayem Cytochrome P450 2E1 (CYP2E1) Is the Principal Enzyme Responsible for Urethane Metabolism: Comparative Studies Using CYP2E1-Null and Wild-Type Mice J. Pharmacol. Exp. Ther., May 1, 2003; 305(2): 557 - 564. [Abstract] [Full Text] [PDF]
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C. J. Henderson, D. M. E. Otto, D. Carrie, M. A. Magnuson, A. W. McLaren, I. Rosewell, and C. R. Wolf Inactivation of the Hepatic Cytochrome P450 System by Conditional Deletion of Hepatic Cytochrome P450 Reductase J. Biol. Chem., April 4, 2003; 278(15): 13480 - 13486. [Abstract] [Full Text] [PDF]
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 C. Lejus, C. Le Roux, E. Legendre, M. Renaudin, H. L. Boiteau, and M. Pinaud Fluoride excretion in children after sevoflurane anaesthesia Br. J. Anaesth., November 1, 2002; 89(5): 693 - 696. [Abstract] [Full Text] [PDF]
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H. Wang, B. Chanas, and B. I. Ghanayem Cytochrome P450 2E1 (CYP2E1) is Essential for Acrylonitrile Metabolism to Cyanide: Comparative Studies Using CYP2E1-Null and Wild-Type Mice Drug Metab. Dispos., August 1, 2002; 30(8): 911 - 917. [Abstract] [Full Text] [PDF]
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M.-A. Bae, J.-E. Pie, and B. J. Song Acetaminophen Induces Apoptosis of C6 Glioma Cells by Activating the c-Jun NH2-Terminal Protein Kinase-Related Cell Death Pathway Mol. Pharmacol., October 1, 2001; 60(4): 847 - 856. [Abstract] [Full Text] [PDF]
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M. J. Beck, C. McLellan, R. L.-F. Lightle, M. A. Philbert, and C. Harris Spatial Glutathione and Cysteine Distribution and Chemical Modulation in the Early Organogenesis-Stage Rat Conceptus in Utero Toxicol. Sci., July 1, 2001; 62(1): 92 - 102. [Abstract] [Full Text] [PDF]
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 E. Waters, J. H. Wang, H. P. Redmond, Q. D. Wu, E. Kay, and D. Bouchier-Hayes Role of taurine in preventing acetaminophen-induced hepatic injury in the rat Am J Physiol Gastrointest Liver Physiol, June 1, 2001; 280(6): G1274 - G1279. [Abstract] [Full Text] [PDF]
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H. Dong, R. L. Haining, K. E. Thummel, A. E. Rettie, and S. D. Nelson Involvement of Human Cytochrome P450 2D6 in the Bioactivation of Acetaminophen Drug Metab. Dispos., April 13, 2001; 28(12): 1397 - 1400. [Abstract] [Full Text]
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W. L. Trepicchio, M. Bozza, P. Bouchard, and A. J. Dorner Protective Effect of rhIL-11 in a Murine Model of Acetaminophen-Induced Hepatotoxicity Toxicol Pathol, February 1, 2001; 29(2): 242 - 249. [Abstract] [PDF]
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B. I. Ghanayem, Hongbing Wang, and S. Sumner Using Cytochrome P-450 Gene Knock-Out Mice to Study Chemical Metabolism, Toxicity, and Carcinogenicity Toxicol Pathol, November 1, 2000; 28(6): 839 - 850. [Abstract] [PDF]
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J. F. Mahler The Use of Genetically Altered Animals in Toxicology Toxicol Pathol, May 1, 2000; 28(3): 447 - 449. [PDF]
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 F. P. Guengerich Metabolism of chemical carcinogens Carcinogenesis, March 1, 2000; 21(3): 345 - 351. [Abstract] [Full Text] [PDF]
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T. L. Horn, T. D. O'Brien, L. B. Schook, and M. S. Rutherford Acute Hepatotoxicant Exposure Induces TNFR-Mediated Hepatic Injury and Cytokine/Apoptotic Gene Expression Toxicol. Sci., March 1, 2000; 54(1): 262 - 273. [Abstract] [Full Text] [PDF]
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H. Kono, B. U. Bradford, M. Yin, K. K. Sulik, D. R. Koop, J. M. Peters, F. J. Gonzalez, T. McDonald, A. Dikalova, M. B. Kadiiska, et al. CYP2E1 is not involved in early alcohol-induced liver injury Am J Physiol Gastrointest Liver Physiol, December 1, 1999; 277(6): G1259 - G1267. [Abstract] [Full Text] [PDF]
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B. I. Ghanayem, J. M. Sanders, B. Chanas, L. T. Burka, and F. J. Gonzalez Role of Cytochrome P-450 2E1 in Methacrylonitrile Metabolism and Disposition J. Pharmacol. Exp. Ther., May 1, 1999; 289(2): 1054 - 1059. [Abstract] [Full Text]
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J. Gu, Q.-Y. Zhang, M. B. Genter, T. W. Lipinskas, M. Negishi, D. W. Nebert, and X. Ding Purification and Characterization of Heterologously Expressed Mouse CYP2A5 and CYP2G1: Role in Metabolic Activation of Acetaminophen and 2,6-Dichlorobenzonitrile in Mouse Olfactory Mucosal Microsomes J. Pharmacol. Exp. Ther., June 1, 1998; 285(3): 1287 - 1295. [Abstract] [Full Text]
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 M. Pirmohamed, A. M Breckenridge, N. R Kitteringham, and B K. Park Fortnightly review: Adverse drug reactions BMJ, April 25, 1998; 316(7140): 1295 - 1298. [Full Text]
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K. J. Woodcroft and R. F. Novak Xenobiotic-Enhanced Expression of Cytochromes P450 2E1 and 2B in Primary Cultured Rat Hepatocytes Drug Metab. Dispos., April 1, 1998; 26(4): 372 - 378. [Abstract] [Full Text]
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J. L. Raucy, E. D. Schultz, M. R. Wester, S. Arora, D. E. Johnston, J. L. Omdahl, and S. P. Carpenter Human Lymphocyte Cytochrome P450 2E1, a Putative Marker for Alcohol-Mediated Changes in Hepatic Chlorzoxazone Activity Drug Metab. Dispos., December 1, 1997; 25(12): 1429 - 1435. [Abstract] [Full Text]
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Extended Abstracts Toxicol Pathol, November 1, 1997; 25(6): 674 - 696. [PDF]
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L. Zhou, R. R. Erickson, J. P. Hardwick, S. S. Park, S. A. Wrighton, and J. L. Holtzman Catalysis of the Cysteine Conjugation and Protein Binding of Acetaminophen by Microsomes from a Human Lymphoblast Line Transfected with the cDNAs of Various Forms of Human Cytochrome P450 J. Pharmacol. Exp. Ther., May 1, 1997; 281(2): 785 - 790. [Abstract] [Full Text]
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Y. Hu, M. Oscarson, I. Johansson, Q.-Y. Yue, M.-L. Dahl, M. Tabone, S. Arinco, E. Albano, and M. Ingelman-Sundberg Genetic Polymorphism of Human CYP2E1: Characterization of Two Variant Alleles Mol. Pharmacol., March 1, 1997; 51(3): 370 - 376. [Abstract] [Full Text] [PDF]
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