Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019158 (hepatitis)
 30,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

"Anti-liver/kidney microsome" (anti-LKM) autoantibodies have been found in the serum of patients with cryptogenic chronic hepatitis and with immunoallergic drug-induced hepatitis, such as those induced by halothane or by tienilic acid (called anti-LKM2 in this case). So far the nature of the human microsomal macromolecules recognized by these antibodies has not been determined. Here we show, by using immunoblot techniques, that among the macromolecules present in human adult liver microsomes, one protein called cytochrome P-450-8 is specifically recognized by most sera of patients containing anti-LKM2 antibodies but not by control serum. Human fetal liver microsomes that do not contain cytochrome P-450-8 are not recognized by the anti-LKM2 antibodies. It is also shown that anti-cytochrome P-450-8 antibodies as well as human serum containing anti-LKM2 antibodies specifically inhibit the hydroxylation of tienilic acid by human liver microsomes. These results indicate that anti-LKM2 antibodies appearing in patients with hepatitis and concomitant administration of tienilic acid are directed against a cytochrome P-450 isoenzyme that catalyzes the metabolic oxidation of this drug. This suggests a possible mechanism for the appearance of anti-organelle antibodies in a drug-induced hepatitis.
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PMID:Human anti-endoplasmic reticulum autoantibodies appearing in a drug-induced hepatitis are directed against a human liver cytochrome P-450 that hydroxylates the drug. 354 Sep 68

The spontaneous course of the galactosamine-hepatitis in the guinea-pig (750 and 1000 mg/kg GalN iv respectively) is characterized by a terminal hypoglycemia together with hypothermia and arterial hypotension fifty-nine hours on average after GalN-application. Preventing hypoglycemia and hypothermia by continuous intravenous infusion of a glucose solution and by increasing room temperature, the animals do not develop hepatic coma, but show an increasing disturbance of the righting reflex and survive at least seventy-two hours. Plasma biochemical tests and liver histology reflect severe hepatic damage. A twofold increase of the liver weight is caused by raised water and lipid content combined with a concomitant depletion of liver glycogen. Pharmacological studies with 14C-Pentobarbital result in a distinctly diminished clearance and in a prolonged half life while the cytochrome P-450 content of the liver shows a moderate decrease. In animal models of acute liver failure the possible incidence of hypoglycemia, arterial hypotension and hypothermia should be considered.
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PMID:[Galactosamine-induced acute liver failure in the guinea pig--spontaneous course and controlled study conditions]. 371 20

Drug interactions involving macrolides have been mainly reported in subjects receiving troleandomycin and in a few receiving erythromycin derivatives. In rats and in humans, troleandomycin, erythromycin and erythromycin derivatives induce microsomal enzymes; the induced isozymes of cytochrome P-450 have a high activity for these macrolides but a poor activity with several other substrates. These isozymes actively demethylate and oxidize these macrolides into nitrosoalkanes which form stable, inactive complexes with the iron of cytochrome P-450. Eventually, the oxidative metabolism of other drugs may be decreased. These effects are marked after administration of troleandomycin, moderate after administration of erythromycin derivatives and absent (or negligible) after administration of spiramycin, josamycin or midecamycin. A second adverse effect of the administration of troleandomycin or erythromycin derivatives is the possible occurrence of hepatitis. Mild hepatic dysfunction is fairly frequent and may be toxic in type. In contrast, jaundice is common, is frequently associated with hypersensitivity, and promptly recurs when the drug is readministered. Troleandomycin and erythromycin derivatives, which form nitrosoalkanes, produce hepatitis, whereas josamycin, midecamycin and spiramycin, which do not form cytochrome P-450-nitrosoalkane complexes, rarely, if ever, produce hepatitis. Nitrosoalkanes are unstable intermediates which react with glutathione but also with cysteine and might covalently bind to the SH-groups of proteins. The following mechanism might be proposed as a hypothetical attempt to link up these various observations. The macrolide (or its reactive metabolite) may have discrete toxicity; in several subjects, this may produce minor liver lesions and a mildly raised aminotransferase activity. Necrosis of a few hepatocytes may release into the circulation plasma membrane proteins altered by the covalent binding of metabolites. Such modified liver antigens may be recognized as foreign and may trigger, in an exceptional subject, an immunoallergic type of clinical hepatitis.
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PMID:Drug interactions and hepatitis produced by some macrolide antibiotics. 387 43

The relationship between hepatic glycerolipids and microsomal drug-metabolizing enzymes was studied in liver biopsies from 41 subjects. The series included obese, diabetic, epileptic and chronic alcoholic patients, all of whom were hospitalized for suspected hepatic ailments (fatty liver, hepatitis or cirrhosis). Therapy with enzyme-inducing anticonvulsants was associated with high phospholipid and cytochrome P-450 and low triacylglycerol concentration in the liver. In patients with fatty liver or cirrhosis low phospholipid and cytochrome P-450 and high triacylglycerol concentrations were observed. There was a significant correlation (r (Pearson's product moment correlation coefficient) = 0.91) between the hepatic phospholipid and cytochrome P-450 concentration. The cytochrome P-450 concentration was inversely related (r = -0.74) to the triacylglycerol concentration. The positive correlation between hepatic phospholipids and drug-metabolizing enzymes could be interpreted as indicating that in human liver phospholipid and cytochrome P-450 synthesis share common regulators, or that phospholipids are necessary for the maximum rate of cytochrome P-450 synthesis.
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PMID:Relationship between lipid composition and drug metabolizing capacity of human liver. 398 78

The effects of rifampicin (RMP) on isoniazid (INH) metabolism in rabbits were examined from the viewpoint of extensive hepatitis. After the RMP pretreatment, no remarkable changes were observed in the plasma levels of INH as well as its metabolites, acetylisoniazid (AcINH), acetylhydrazine (AcHz) and diacetylhydrazine (DAcHz) with the exception of hydrazine (Hz). After an oral administration of INH or Hz hydrate, the stochastic examination showed that the AUC0-8hr values of Hz plasma levels in RMP pretreated groups were significantly less than those in the control rabbits. RMP treatment was also shown to induce rabbit liver cytochrome P-450 activity. Histological studies demonstrated that Hz causes more remarkable hepatic necrosis in rabbits pretreated with RMP than in the control rabbits. These observations could suggest that Hz is a key intermediate of INH-hepatitis through the transformation of some hepatotoxic species by microsomal oxidation that is facilitated by RMP.
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PMID:Is isoniazid-hepatotoxicity induced by the metabolite, hydrazine? 667 29

Chronic diseases of the liver were found to be associated with microsomal hydroxylation reactions inhibition, this inhibition depending on the disease activity and stage. Chronic cholestatic hepatitis and primary biliary cirrhosis are associated with a more marked suppression of these reactions, the degree of inhibition being in proportion with the cholestatic syndrome severity. Demethylation process was found inhibited in active liver cirrhosis and primary biliary cirrhosis. The authors believe that assessment of the rate of microsomal oxidation in a liver biopsy specimen will help objectively assess the first phase of cytochrome P-450 effected biotransformation (hydroxylation) in patients with chronic disease.
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PMID:[Cytochrome P-450-dependent hydroxylation in liver tissue of patients with hepatobiliary diseases]. 803 24

We attempted to produce a model mouse with a liver injury resulting from an immunological mechanism in C57BL/6J mice, and the effect of hepatitis on the hepatic microsomal mixed-function oxidase system was studied. An experimental immunological liver injury model was caused by the intravenous injection of an anti-basic liver protein (BLP) antibody in mice which had been previously immunized with normal rabbit IgG (RGG) and complete Freund's adjuvant. C57BL/6J strain mice showed the highest susceptibility to the immunological liver injury. Typical histopathological changes in the liver included submassive hepatocellular necrosis and infiltration of lymphocytes into the portal tract and sinusoid area in a necrotic lesion. The liver injury in this model was markedly inhibited by the administration of prednisolone (20 mg/kg, p.o.), cyclophosphamide (15 mg/kg, i.p.), levamisole (10 mg/kg, p.o.), glycyrrhizin (50 mg/kg, i.p.) and cepharanthine (10 mg/kg, i.p.), which act on the immune system. Twenty-four hours after the injection of anti-BLP antibody, the activities of aminopyrine N-demethylase, aniline hydroxylase and NADPH-cytochrome c reductase and the content of cytochrome P-450 were mostly reduced, whereas cytochrome b5 and NADH-ferricyanide reductase were not. These results suggest that the experimental liver injury model in C57BL/6J mice is useful as a model of liver injury model, and its hepatitis was shown to inhibit the cytochrome P-450-dependent biotransformation of drugs in the mouse.
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PMID:Effect of anti-basic liver protein antibody-induced liver injury on hepatic drug-metabolizing enzymes in C57 BL/6J mice. 828 50

The in vitro metabolic activation of flutamide, a nitroaromatic antiandrogen which produces hepatitis in a few recipients, was first studied with male rat liver microsomes. There was no electron spin resonance evidence for the reduction of flutamide by reduced nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome P-450 reductase into a nitro anion free radical. In contrast, flutamide was oxidatively transformed by cytochrome P-450 into reactive metabolite(s) that covalently bound to microsomal proteins. Covalent binding required oxygen and NADPH, and was decreased by the nucleophile glutathione and by the cytochrome P-450 inhibitors SKF 525-A, piperonyl butoxide and troleandomycin (an inhibitor of the cytochrome P-450 3A subfamily). Covalent binding was increased markedly by pretreatment with dexamethasone (an inducer of the cytochrome P-450 3A subfamily) and moderately by pretreatment with beta-naphthoflavone (an inducer of the 1A family). Covalent binding was immunoinhibited markedly by anticytochrome P-450 3A immunoglobulin G and moderately by anticytochrome P-450 1A immunoglobulin G. Covalent binding was much lower with liver microsomes from female rats (not expressing P-450 3A2). Covalent binding of flutamide also occurred with human liver microsomes (where it was inhibited by troleandomycin), and with yeast microsomes expressing human liver cytochromes P-450 1A1, 1A2 or 3A4. We concluded that flutamide was oxidatively transformed into chemically reactive metabolite(s) by rat and human cytochromes P-450, including forms belonging to the 3A and 1A subfamilies.
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PMID:Metabolic activation of the nitroaromatic antiandrogen flutamide by rat and human cytochromes P-450, including forms belonging to the 3A and 1A subfamilies. 838 41

Autoimmune hepatitis is characterized by hypergammaglobulinemia, female predominance, autoantibodies and a good response to immunosuppression, and is based on specific autoantibodies and clinical characteristics. Several subgroups may be distinguished. As in most autoimmune diseases, the etiology is unknown. The association of autoimmune hepatitis with a viral etiology is most prominent in autoimmune hepatitis type 2 which is characterized by liver/kidney microsomal (LKM-1) autoantibodies against cytochrome P-450 II D6. Depending on the geographical origin of the patients, a specific proportion of patients with autoimmune hepatitis type 2 is associated with hepatitis C virus infection. These HCV RNA-positive patients are older, female predominance is not profound, and response to immunosuppression is generally low compared to the HCV-negative patients with autoimmune hepatitis type 2. The genetic background is unclear. HCV sequence analysis revealed that HCV genotype II is prominent in HCV-positive autoimmune hepatitis type 2. HCV mutants with deletions in the HCV envelope region were identified. The relevance of these HCV mutants for the induction of autoimmunity needs to be characterized further. The HCV-negative population of patients with autoimmune hepatitis type 2 seems to have a relation with herpes simplex virus (HSV-1) infection since the B-cell epitope of cytochrome P-450 II D6, the major LKM-1 antigen, shares sequence homology with the IE-175 protein of HSV-1. In the HCV-negative population of autoimmune hepatitis type 2, HLA-DR3 and C4-AQ0 alleles are significantly increased.
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PMID:Viruses and autoimmune liver disease. 840 37

Studies were carried out to test the hypothesis that inflammatory liver disease increases the expression of specific cytochrome P-450 isoenzymes involved in aflatoxin B1 (AFB) activation. The immunohistochemical expression and localization of various human cytochrome P-450 isoforms, including CYP2A6, CYP1A2, CYP3A4, and CYP2B1, were examined in normal human liver and liver with hepatitis and cirrhosis. The constitutive expression of CYP3A4 in normal liver showed a characteristic pattern of distribution in centrilobular hepatocytes, whereas CYP1A2, CYP2A6, and CYP2B1 were expressed uniformly throughout the liver acinus. In sections of liver infected with hepatitis B virus (HBV) or hepatitis C virus (HCV), the expression of CYP2A6 was markedly increased in hepatocytes immediately adjacent to areas of fibrosis and inflammation. CYP3A4 and CYP2B1 were induced to a lesser degree, and expression of CYP1A2 was unaffected. In HBV-infected liver, double immunostaining revealed that overexpression of CYP2A6 occurred in hepatocytes expressing the HBV core antigen. In HCV-infected liver, CYP2A6, CYP3A4, and CYP2B1 were overexpressed in hepatocytes with hemosiderin pigmentation. These results suggest that alterations in phenotypic expression of specific P-450 isoenzymes in hepatocytes associated with hepatic inflammation and cirrhosis might increase susceptibility to AFB genotoxicity.
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PMID:Overexpression of cytochrome P-450 isoforms involved in aflatoxin B1 bioactivation in human liver with cirrhosis and hepatitis. 886 87


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