Assessment of platelet function in healthy cats in response to commonly prescribed antiplatelet drugs using three point-of-care platelet function tests.

Objectives The objective was to determine if decreased platelet function could be detected after treatment with aspirin and/or clopidogrel in healthy cats using three point-of-care platelet function tests that evaluate platelet function by different methods: Multiplate (by impedance), Platelet Function Analyzer 100 (by mechanical aperture closure) and Plateletworks (by platelet counting). Methods Thirty-six healthy cats were randomly assigned to receive one of three oral treatments over an 8 day period: (1) aspirin 5 mg q72h; (2) aspirin 20.25 mg q72h; or (3) clopidogrel 18.75 mg q24h. Cats treated with 5 and 20.25 mg aspirin also received clopidogrel on days 4-8. Platelet aggregation in response to adenosine diphosphate and collagen ± arachidonic acid was assessed on days 1 (baseline), 4 and 8. Aspirin and clopidogrel metabolites were measured by high-performance liquid chromatography. Platelet function in response to treatment was analyzed by ANCOVA, linear regression and Spearman correlation. Results The only solitary aspirin effect was detected using Plateletworks with collagen in cats treated with 20.25 mg. The only effect detected by Multiplate was using arachidonic acid in cats treated with both aspirin 20.25 mg and clopidogrel. All clopidogrel treatment effects were detected by Platelet Function Analyzer 100, Plateletworks (adenosine diphosphate) and Plateletworks (collagen). Drug metabolites were present in all cats, but concentrations were minimally correlated to platelet function test results. Conclusions and relevance Platelet Function Analyzer 100 and Plateletworks using adenosine diphosphate ± collagen agonists may be used to detect decreased platelet function in response to clopidogrel treatment. Either aspirin is not as effective an antiplatelet drug as clopidogrel, or the tests used were not optimal to measure aspirin effect. Cats with heart disease are commonly prescribed antiplatelet drugs to decrease the risk of aortic thromboembolism. Platelet Function Analyzer 100 and Plateletworks may be useful for confirming clopidogrel treatment in these cats.

Assessment of platelet function in healthy sedated cats using three whole blood platelet function tests.

The objectives of this study were to establish feline references intervals for 3 commercial whole blood platelet function test analyzer systems: Multiplate analyzer (MP; Roche Diagnostics International Ltd., Rotkreuz, Switzerland), Platelet Function Analyzer-100 (PF: Siemens Canada, Mississauga, Ontario, Canada), and Plateletworks Combo-25 kit (PW; Helena Laboratories, Beaumont, TX). Venipuncture was performed on 55 healthy sedated cats, and platelet aggregation in response to adenosine diphosphate (ADP), collagen (COL), and arachidonic acid (AA; MP only) was assessed using citrated blood. For the MP analyzer, median (95% confidence intervals [CIs]) area under curve (Units) for ADP, COL, and AA agonists were 87 (11-176), 81 (32-129), and 91 (59-129), respectively. For the PF analyzer, median (95% CIs) closure time, using COL-ADP cartridges, was 69 (46-89) sec. For the PW assay, median (95% CIs) percent aggregations for ADP and COL agonists were 71 (18-92) and 49 (9-96), respectively, using impedance hematology analyzer platelet counts, and 94 (25-98) and 68 (14-119), respectively, using flow cytometry hematology analyzer platelet counts. There were low correlations between the PF analyzer (COL-ADP cartridge) and MP analyzer (COL agonist; ρ = 0.11), and between the PF analyzer (COL-ADP cartridge) and PW assay (COL agonist using impedance platelet counts; ρ = 0.14). The PW assay percent aggregations using impedance and flow cytometric platelet counts were correlated for both ADP (ρ = 0.64) and COL (ρ = 0.64) agonists. Platelet function testing using these tests are feasible in cats, but 95% CIs are wide, so single results may be difficult to interpret. Platelet counting by impedance or flow cytometry may be used for the PW assay but are not interchangeable.

Cytochrome P450 2A5 and bilirubin: mechanisms of gene regulation and cytoprotection.

Bilirubin (BR) has recently been identified as the first endogenous substrate for cytochrome P450 2A5 (CYP2A5) and it has been suggested that CYP2A5 plays a major role in BR clearance as an alternative mechanism to BR conjugation by uridine-diphosphate glucuronyltransferase 1A1. This study investigated the mechanisms of Cyp2a5 gene regulation by BR and the cytoprotective role of CYP2A5 in BR hepatotoxicity. BR induced CYP2A5 expression at the mRNA and protein levels in a dose-dependent manner in primary mouse hepatocytes. BR treatment also caused nuclear translocation of Nuclear factor-E2 p45-related factor 2 (Nrf2) in hepatocytes. In reporter assays, BR treatment of primary hepatocytes transfected with a Cyp2a5 promoter-luciferase reporter construct resulted in a 2-fold induction of Cyp2a5 reporter activity. Furthermore, cotransfection of the hepatocytes with a Nrf2 expression vector without BR treatment resulted in an increase in Cyp2a5 reporter activity of approximately 2-fold and BR treatment of Nrf2 cotransfectants further increased reporter activity by 4-fold. In addition, site-directed mutation of the ARE in the reporter construct completely abolished both the BR- and Nrf2-mediated increases in reporter activity. The cytoprotective role of CYP2A5 against BR-mediated apoptosis was also examined in Hepa 1-6 cells that lack endogenous CYP2A5. Transient overexpression of CYP2A5 partially blocked BR-induced caspase-3 cleavage in Hepa 1-6 cells. Furthermore, in vitro degradation of BR was increased by microsomes from Hepa 1-6 cells overexpressing CYP2A5 compared to control cells transfected with an empty vector. Collectively, these results suggest that Nrf2-mediated CYP2A5 transactivation in response to BR may provide an additional mechanism for adaptive cytoprotection against BR hepatotoxicity.

Low levels of GSTA1 expression are required for Caco-2 cell proliferation.

The colonic epithelium continuously regenerates with transitions through various cellular phases including proliferation, differentiation and cell death via apoptosis. Human colonic adenocarcinoma (Caco-2) cells in culture undergo spontaneous differentiation into mature enterocytes in association with progressive increases in expression of glutathione S-transferase alpha-1 (GSTA1). We hypothesize that GSTA1 plays a functional role in controlling proliferation, differentiation and apoptosis in Caco-2 cells. We demonstrate increased GSTA1 levels associated with decreased proliferation and increased expression of differentiation markers alkaline phosphatase, villin, dipeptidyl peptidase-4 and E-cadherin in postconfluent Caco-2 cells. Results of MTS assays, BrdU incorporation and flow cytometry indicate that forced expression of GSTA1 significantly reduces cellular proliferation and siRNA-mediated down-regulation of GSTA1 significantly increases cells in S-phase and associated cell proliferation. Sodium butyrate (NaB) at a concentration of 1 mM reduces Caco-2 cell proliferation, increases differentiation and increases GSTA1 activity 4-fold by 72 hours. In contrast, 10 mM NaB causes significant toxicity in preconfluent cells via apoptosis through caspase-3 activation with reduced GSTA1 activity. However, GSTA1 down-regulation by siRNA does not alter NaB-induced differentiation or apoptosis in Caco-2 cells. While 10 mM NaB causes GSTA1-JNK complex dissociation, phosphorylation of JNK is not altered. These findings suggest that GSTA1 levels may play a role in modulating enterocyte proliferation but do not influence differentiation or apoptosis.

Ultrasonographic and laboratory screening in clinically normal mature golden retriever dogs.

Wellness and pre-anesthetic screening of blood and urine of geriatric companion animals are routinely recommended. In addition, there are occasional references to the use of imaging in clinically normal geriatric patients. However, the utility of wellness testing is not known, and there is limited information regarding the value of pre-anesthetic testing. Wellness testing, including complete blood cell count, biochemical profile, urinalysis, and abdominal ultrasound, was performed on 53 clinically normal, mature golden retriever dogs. Laboratory analysis revealed abnormalities in 54.7% (29/53) of the dogs. Abdominal ultrasound screening demonstrated abnormalities in 64.2% (34/53) of the dogs. As only a small number of dogs had follow-up diagnostic testing available, the significance of these abnormalities is unknown. Further study involving a larger cohort of animals and analysis of follow-up data is necessary to determine the utility of laboratory and imaging studies in clinically normal geriatric patients.

The effect of menadione on glutathione S-transferase A1 (GSTA1): c-Jun N-terminal kinase (JNK) complex dissociation in human colonic adenocarcinoma Caco-2 cells.

Glutathione S-transferases (GSTs) act as modulators of mitogen-activated protein kinase signal transduction pathways via a mechanism involving protein-protein interactions. We have demonstrated that GSTA1 forms complexes with JNK and modifies JNK activation during cellular stress, but the factors that influence complex association and dissociation are unknown. We hypothesized that menadione causes dissociation of GSTA1-JNK complexes, activates JNK, and the consequences of menadione exposure depend on GSTA1 expression. We demonstrate that menadione causes GSTA1-JNK dissociation and JNK activation in preconfluent Caco-2 cells, whereas postconfluent cells are resistant to this effect. Moreover, preconfluent cells are more sensitive than postconfluent cells to menadione-induced cytotoxicity. Activation of JNK is transient since removal of menadione causes GSTA1 to re-associate with JNK reducing cytotoxicity. Over-expression and knockdown of GSTA1 did not alter JNK activation by menadione or sensitivity to menadione-induced cytotoxicity. These results indicate that GSTA1-JNK complex integrity does not affect the ability of menadione to activate JNK. N-acetyl cysteine prevents GSH depletion and blocks menadione-induced complex dissociation, JNK activation and inhibits menadione-induced cytotoxicity. JNK activation and inhibits menadione-induced cytotoxicity. The data suggest that the mechanism of menadione-induced JNK activation involves the production of reactive oxygen species, likely superoxide anion, and intracellular GSH levels play an important role in preventing GSTA1-JNK complex dissociation, subsequent JNK activation and induction of cytotoxicity.

Proteomic analysis of plasma from Holstein cows testing positive for Mycobacterium avium subsp. paratuberculosis (MAP).

Johne's disease (JD) is a widespread and economically important chronic inflammatory disease of the small intestine of ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). Although there are several techniques available for diagnosis of JD, their sensitivity is questionable. New proteome profiling methods, such as serum/plasma protein fingerprinting by 2-Dimensional Fluorescence Difference Gel Electrophoresis (2D-DIGE), may therefore be useful for identifying novel protein biomarkers of MAP infection. In this study, plasma samples were collected from 380 Holstein cows and screened for the presence of MAP infection using the M.pt. Johne's antibody Kit (IDEXX). Five negative (MAP-), and 5 strongly positive (MAP+) cows were selected for proteomic analysis. Highly abundant proteins were depleted from the plasma samples using the ProteoMiner technology (Bio-Rad) to enhance the resolution of low abundance proteins. Plasma samples from MAP-, MAP+, and a pooled internal control were labelled with different fluorescent dyes and separated based on their isoelectrical point (IP) and then their molecular weight. Gel images of the fluorescent plasma protein maps were acquired using a Typhoon scanner and analyzed using the DeCyder software. Proteins that were differentially expressed were excised from the gels, trypsin digested, and subjected to MS/MS analysis for identification. Six proteins were identified as being up-regulated at least 2-fold in MAP+ cows including: transferrin, gelsolin isoforms α & ß (actin binding protein - ABP), complement subcomponent C1r, complement component C3, amine oxidase - copper containing 3 (AOC3), and coagulation factor II (thrombin) (p<0.05). Two proteins that were down-regulated approximately 2-fold in the MAP+ cows included coagulation factor XIII -B polypeptide (COAFXIII), and fibrinogen γ chain (FGG) and its precursor.

CYP2A5 induction and hepatocellular stress: an adaptive response to perturbations of heme homeostasis.

Unlike most cytochrome P450 (CYP) enzymes, murine hepatic CYP2A5 is induced during pathological conditions that result in liver injury including hepatotoxicity mediated by xenobiotics, hepatitis caused by various microbial agents and liver neoplasia. Since CYP2A5 metabolizes various important xenobiotics including nicotine and pro-carcinogens such as nitrosamines and aflatoxin B(1), altered gene expression could affect tobacco addiction, hepatotoxicity and hepatocarcinogenesis. This article synthesizes the current knowledge concerning hepatic expression of Cyp2a5 including the transcriptional and post-transcriptional regulatory mechanisms, pathophysiological conditions associated with enzyme induction such as oxidative and endoplasmic reticulum stress and altered lipid and energy homeostasis as well as the known exogenous and putative endogenous substrates. Knowledge of the stimuli responsible for the unique overexpression of CYP2A5 during liver injury may provide clues to a functional role for this enzyme and the impact of variable CYP2A5 expression on xenobiotic metabolism and toxicity, disease development and the adaptive response to hepatocellular stress.

Expression of cytochrome P450 2A5 in a glucose-6-phosphate dehydrogenase-deficient mouse model of oxidative stress.

Murine hepatic cytochrome P450 2A5 (CYP2A5), unlike most CYP enzymes, is upregulated during hepatitis and hepatotoxic conditions, but the common stimulus for its induction remains unknown. We investigated the involvement of oxidative stress in the regulation of CYP2A5 expression using an oxidative stress-sensitive glucose-6-phosphate dehydrogenase (G6PD)-deficient mouse model. Treatment of deficient and wild-type mice with the prototypical CYP2A5-inducer pyrazole for 72h led to a significantly greater degree of induction of CYP2A5 mRNA, protein and activity in deficient mice, with the greatest increase observed in animals homozygous for the deficiency. However, markers of oxidative stress including protein carbonyl, 8-hydroxydeoxyguanosine, malondiadehyde and 4-hydroxyalkenal levels were unaltered with pyrazole treatment. Furthermore, CYP2A5 expression was not altered in G6PD-deficient mice treated with the pro-oxidant menadione whereas DNA, lipid, and protein markers of oxidative stress were significantly increased. The antioxidant polyethylene glycol-conjugated catalase, while decreasing oxidative stress in menadione-treated mice, did not prevent the induction of CYP2A5 by pyrazole. Finally, the ER stress marker protein, GRP78, was increased following pyrazole treatment in G6PD-deficient compared to wild-type mice. These findings do not support a central role for generalized cellular oxidative stress in the regulation of CYP2A5 and suggest that additional factors related to G6PD-deficiency, such as ER stress, may be involved.

Microarray analysis of hepatic gene expression in pyrazole-mediated hepatotoxicity: identification of potential stimuli of Cyp2a5 induction.

Cytochrome P450 2a5 (Cyp2a5) expression is induced during liver damage caused by hepatotoxins such as pyrazole, however, the mechanism underlying this overexpression is unclear. In order to identify pathophysiological and cellular responses to pyrazole that might alter Cyp2a5 expression, we examined the effect of pyrazole on mouse hepatic gene expression in C57BL/6 mice using Affymetrix 430 2.0 microarrays. Over 3000 differentially expressed genes were identified 24-h after pyrazole treatment that were associated with a variety of cellular pathways. Upregulated genes were primarily involved in the splicing and processing of RNA and the unfolded protein response pathway, while downregulated genes were associated with amino acid and lipid metabolism, and generation of precursor metabolites for energy production. We also examined the effects of pyrazole on cellular pathways linked to metabolic and histopathological changes observed with pyrazole toxicity. Increased mRNA levels were observed for genes involved in bilirubin production, whereas the major genes of the urea cycle were strongly decreased. Changes in genes involved in carbohydrate metabolism were also observed which could explain pyrazole-induced glycogen depletion and decreased serum glucose. In addition, over 100 genes involved in the cellular stress response were upregulated by pyrazole treatment, including genes involved in the unfolded protein response and redox status. Based on these results and previous evidence concerning the regulation of Cyp2a5, we have identified several pathophysiological changes including altered energy homeostasis, hyperbilirubinemia, ER stress, and altered redox status that are associated with CYP2A5 overexpression and may represent potential stimuli for the induction of Cyp2a5.

Dexamethasone-mediated up-regulation of human CYP2A6 involves the glucocorticoid receptor and increased binding of hepatic nuclear factor 4 alpha to the proximal promoter.

Human cytochrome P450 2A6 (CYP2A6) metabolizes various clinically relevant compounds, including nicotine- and tobacco-specific procarcinogens; however, transcriptional regulation of this gene is poorly understood. We investigated the role of the glucocorticoid receptor (GR) in transcriptional regulation of CYP2A6. Dexamethasone (DEX) increased CYP2A6 mRNA and protein levels in human hepatocytes in primary culture. This effect was attenuated by the GR receptor antagonist mifepristone (RU486; 17beta-hydroxy-11beta-[4-dimethylamino phenyl]-17alpha-[1-propynyl]estra-4,9-dien-3-one), suggesting that induction of CYP2A6 by DEX was mediated by the GR. In gene reporter assays, DEX caused dose-dependent increases in luciferase activity that was also prevented by RU486 and progressive truncations of the CYP2A6 promoter delineated DEX-responsiveness to a -95 to +12 region containing an hepatic nuclear factor 4 (HNF4) alpha response element (HNF4-RE). Mutation of the HNF4-RE abrogated HNF4alpha- and DEX-mediated transactivation of CYP2A6. In addition, overexpression of HNF4alpha increased CYP2A6 transcriptional activity by 3-fold. DEX increased HNF4alpha mRNA levels by 4-fold; however, the amount of HNF4alpha nuclear protein was unaltered. Electrophoretic mobility shift, chromatin immunoprecipitation (ChIP), and streptavidin DNA binding assays revealed that DEX increased binding of HNF4alpha to the HNF4-RE and that an interaction of GR and HNF4alpha occurred at this site. Moreover, ChIP assays indicated that histone H4 acetylation of the CYP2A6 proximal promoter chromatin was increased by DEX that may allow for increased binding of HNF4alpha to the HNF4-RE in human hepatocytes. These findings indicate that increased expression of CYP2A6 by DEX is mediated by the GR via a nonconventional transcriptional mechanism involving interaction of HNF4alpha with an HNF4-RE rather than a glucocorticoid response element.

Repression of human GSTA1 by interleukin-1beta is mediated by variant hepatic nuclear factor-1C.

Down-regulation of glutathione transferase A1 (GSTA1) expression has profound implications in cytoprotection against toxic by-products of lipid peroxidation produced during inflammation. We investigated the role of hepatic nuclear factor 1 (HNF-1) in repression of human GSTA1 expression by interleukin (IL)-1beta in Caco-2 cells. In luciferase reporter assays, overexpression of HNF-1alpha increased GSTA1 transcriptional activity via an HNF-1 response element (HRE) in the proximal promoter. In addition, constitutive mRNA levels of GSTA1 and HNF-1alpha rose concurrently in Caco-2 cells with increasing stage of confluence. IL-1beta reduced GSTA1 mRNA levels at all stages of confluence; however, HNF-1alpha mRNA levels were not altered. IL-1beta repressed GSTA1 transcriptional activity, an effect that was abolished by mutating the HRE. Similar results were observed in HT-29 and HepG2 cells. Overexpression of HNF-1alpha did not counteract IL-1beta-mediated repression of GSTA1 transcription either in reporter assays or at the mRNA level. Involvement of the transdominant repressor C isoform of variant HNF-1 (vHNF-1C) in GSTA1 repression was demonstrated, because vHNF-1C overexpression significantly reduced GSTA1 transcriptional activity. Finally, IL-1beta caused concentration-related up-regulation of vHNF-1C mRNA levels and increased binding of vHNF-1C protein to the HRE, whereas HNF-1alpha-HRE complex formation was reduced. These findings indicate that IL-1beta represses GSTA1 transcription via a mechanism involving overexpression of vHNF-1C.

Endoplasmic reticulum stress due to altered cellular redox status positively regulates murine hepatic CYP2A5 expression.

Murine hepatic cytochrome P450 2A5 (CYP2A5) is uniquely induced by a variety of agents that cause liver injury and inflammation, conditions that are typically associated with downregulation of P450s. We hypothesized that induction of CYP2A5 occurs in response to hepatocellular damage resulting in endoplasmic reticulum (ER) stress. Treatment of mice in vivo and mouse hepatocytes in primary culture with the CYP2A5 inducer pyrazole resulted in overexpression of the ER stress biomarker glucose-regulated protein (GRP) 78. Treatment of primary hepatocytes with ER stress activators thapsigargin, tunicamycin, and trans-4,5-dihydroxy-1,2-dithiane (DTT(ox)) and the calcium ionophore A23187 (calcimycin) resulted in elevated GRP78 mRNA levels; however, only the reducing agent DTT(ox) induced levels of CYP2A5 mRNA, protein, and coumarin 7-hydroxylase activity. To test the hypothesis that CYP2A5 induction is due to liver injury resulting from altered cellular redox status, we demonstrated that CYP2A5 induction, elevated serum alanine aminotransferase, and oxidative protein damage occur concurrently in pyrazole-treated mice. Pyrazole also induced the expression of cytosolic alpha and mu class glutathione S-transferase expression both in vivo and in primary mouse hepatocytes. Moreover, treatment of hepatocytes with the redox cycling quinone menadione resulted in overexpression of CYP2A5 and GSTM1 mRNA. Finally, pretreatment of hepatocytes with the antioxidants N-acetylcysteine and vitamin E attenuated pyrazole-mediated increases in CYP2A5 mRNA levels. These findings clearly indicate that induction of mouse hepatic CYP2A5 during liver injury occurs via a novel mechanism involving ER stress due to altered cellular redox status.

Dexrazoxane does not protect against doxorubicin-induced damage in young rats.

Doxorubicin (DOX), an anticancer drug, causes a dose-dependent cardiotoxicity. Some evidence suggests that female children have an increased risk for DOX-mediated cardiac damage. To determine whether the iron chelator dexrazoxane (DXR) could reduce DOX-induced cardiotoxicity in the young, we injected day 10 neonate female and male rat pups with a single dose of saline or DOX, DXR, or DXR + DOX (20:1). We followed body weight gain with growth, measured cardiac hypertrophy after a 2-wk swim exercise program, markers of apoptosis (Bcl-2, BAX, BNIP1, caspase 3 activation), oxidative stress (heme oxygenase 1, protein carbonyl levels), the chaperone protein clusterin, and the transcriptional activator early growth response gene-1 (Egr-1) in hearts of nonexercised and exercised rats on neonate day 38. All DOX-alone and DXR + DOX-treated rats showed decreased weight gain, with female rats affected earlier than male rats. DXR-alone, DOX-alone, and DXR + DOX-treated rats had an increased heart weight-to-body weight (heart wt/body wt) ratio after the exercise program with female rats showing the largest increase in heart wt/body wt. Drug-treated females also showed increased cardiac apoptosis, as measured by the increased expression of the proapoptotic proteins BAX and BNIP1 and the appearance of caspase 3 activation products, and oxidative stress, as measured by increased heme oxygenase 1 expression, and reduced Egr-1 and clusterin expression when compared with the similarly treated male rats. We conclude that DXR preinjection did not reduce DOX-induced noncardiac and cardiac damage and that young female rats were more susceptible to DXR and DOX toxicities than age-matched male rats.

Effects of lipopolysaccharide-stimulated inflammation and pyrazole-mediated hepatocellular injury on mouse hepatic Cyp2a5 expression.

Murine hepatic cytochrome P450 2a5 (Cyp2a5) is induced during hepatotoxicity and hepatitis, however, the specific regulatory mechanisms have not been determined. We compared the influence of acute inflammation elicited in vivo by bacterial endotoxin lipopolysaccharide (LPS) and liver injury caused by the hepatotoxin pyrazole on hepatic Cyp2a5 expression in mice. Pyrazole treatment resulted in statistically significant increases in levels of Cyp2a5 mRNA, protein and catalytic activity by 540, 273 and 711%, respectively (P<0.05). In LPS-treated livers Cyp2a5 expression was significantly reduced compared to controls at the mRNA (46%) protein (35%), and activity (23%) levels (P<0.05). Treatment of mice with recombinant murine interleukin-1 beta and interleukin-6 had no significant effect on Cyp2a5 mRNA and protein levels. Liver injury, as assessed by serum alanine aminotransferase, was greater with pyrazole than with LPS treatment (609 vs 354% of control levels respectively). ER stress, determined by hepatic glucose regulated protein 78 (grp78) levels, was greater with pyrazole (185% of controls) than with LPS (128% of controls). In pyrazole-treated liver, overexpression of immunoreactive grp78 protein revealed that ER stress was localized to pericentral hepatocytes in which Cyp2a5 was induced. Evidence of glycogen loss and membrane damage in these cells was suggestive of oxidative damage. Moreover, vitamin E attenuated Cyp2a5 induction by pyrazole in vivo. These results suggest that induction of Cyp2a5 that has been observed in mouse models of hepatitis and hepatoxicity may be related to oxidative injury to the endoplasmic reticulum of pericentral hepatocytes rather than exposure to pro-inflammatory cytokines.

Loss of glutathione S-transferase (GST) mu phenotype in colorectal adenocarcinomas from patients with a GSTM1 positive genotype.

Glutathione S-transferase (GST) mu phenotype was assessed in colon tissue from patients with ulcerative colitis and colorectal neoplasms that were positive for GSTM1 genotype. GST mu protein (enzyme linked immunosorbent assay) was absent in 2/9 unaffected colon tissue (22.3%), 4/13 tissues with chronic ulcerative colitis (CUC) (30.7%), 4/11 adenomas (36.4%) and 7/14 adenocarcinomas (50.0%; P