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)

Autoantibodies are important diagnostic markers for autoimmune type chronic active hepatitis (AI-CAH) and primary biliary cirrhosis (PBC). At least three subgroups of AI-CAH can be distinguished serologically. Antinuclear antibodies (ANA), smooth muscle antibodies (SMA), and liver membrane autoantibodies (LMA) characterize classical autoimmune type 'lupoid' hepatitis, while liver kidney microsomal (LKM) antibodies identify a second, and antibodies to a soluble liver antigen (anti-SLA), a third subgroup of AI-CAH. Patients with autoimmune type CAH in contrast to patients with virus-induced liver diseases profit from immunosuppressive therapy. PBC is characterized by disease-specific subtypes of antimitochondrial antibodies (AMA). Technical developments, like immunoblotting and molecular cloning, led to a better definition and characterization of autoantibody-antigen systems. Molecular cloning has been successfully applied to identify the main 70 kDa mitochondrial antigen in PBC. This and other mitochondrial autoantigens have been identified as enzymes: E2 component of pyruvate dehydrogenase (PDH-E2) and its component X, branched chain alpha-keto acid dehydrogenase (BCKD-E2), and 2-oxoglutarate dehydrogenase. LKM-1 antigen has been identified as cytochrome P-450 db1, a drug metabolizing enzyme with a known genetic polymorphism. These cloned hepatic autoantigens share some characteristics with other autoantigens: they are enzymes, autoantibodies react with active sites of these enzymes and the autoepitopes are highly conserved. After the identification of these autoepitopes, specific and sensitive diagnostic reagents will become available. B and T cell epitope mapping will help to elucidate whether these autoantibodies are just clinically valuable diagnostic markers or whether they contribute to the immunopathogenesis or help to identify the aetiological agents.
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PMID:Autoantibodies and antigens in liver diseases--updated. 268 96

Anti-CF3CO antibodies, monospecific toward trifluoroacetylated proteins (CF3CO-proteins), which are elicited in experimental animals and humans exposed to the anesthetic agent halothane, cross-react with an unknown protein of approximately 52 kDa, constitutively expressed in tissues of experimental animals and humans not previously exposed to the agent. Using anti-CF3CO antibody, the protein(s) of 52 kDa could be immunoprecipitated from solubilized rat heart homogenate. Two-dimensional gel electrophoretic analysis revealed the presence of distinct major (P1, P2) and minor (P3, P4, P5) protein components with apparent molecular masses of 52 kDa. From each of the components P1 and P2, the amino acid sequences of three peptides were determined and found to exhibit 100% identity with the corresponding amino acid sequences of the E2 subunit of the rat 2-oxoglutarate dehydrogenase complex (OGDC). Additionally to the E2 subunit of OGDC, anti-CF3CO antibody also recognized on immunoblots the purified E2 subunit of the branched chain 2-oxoacid dehydrogenase complex (BCOADC) and protein X, a constituent of the pyruvate dehydrogenase complex (PDC), in a manner sensitive to competition by N6-(trifluoroacetyl)-L-lysine (CF3CO-Lys), 6(RS)-lipoic acid, and N6-(6(RS)-lipoyl)-L-lysine (lipoyl-Lys). Furthermore, a discrete population of autoantibodies was identified in sera of patients with halothane hepatitis which could not discriminate between the lipoylated target epitope present on the E2 subunit of OGDC and epitopes on CF3CO-RSA, used as model for CF3CO-proteins. These data suggest that the autoantigenicity of these proteins in halothane hepatitis is based on the molecular mimicry of CF3CO-Lys by lipoic acid, the prosthetic group common to protein X and the E2 subunits of OGDC and BCOADC.
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PMID:The lipoic acid containing components of the 2-oxoacid dehydrogenase complexes mimic trifluoroacetylated proteins and are autoantigens associated with halothane hepatitis. 754 57

The detection of antimitochondrial autoantibodies (AMAs) is critical in the diagnosis of primary biliary cirrhosis (PBC). However, conventional laboratory assays to detect AMA are dependent on the time-consuming method of immunofluorescence microscopy, a method often plagued by problems of nonspecificity. AMAs react against mitochondrial autoantigens including the E2 components of the pyruvate dehydrogenase complex (PDC-E2), the branched-chain 2-oxo-acid dehydrogenase complex (BCOADC-E2), and the 2-oxo-glutarate dehydrogenase complex (OGDC-E2). Interestingly, the immunodominant epitopes of PDC-E2, BCOADC-E2, and OGDC-E2 are all conformational lipoate binding sites, but antibodies against them do not cross-react. Although 80% to 90% of sera from patients with PBC react to PDC-E2, approximately 10% patients with PBC react only to BCOADC-E2 and/or OGDC-E2. We have taken advantage of our epitope-mapping studies of the E2 components of PDC, BCOADC, and OGDC, and constructed a "designer" hybrid clone, designated as pML-MIT3, that coexpresses the immunodominant epitopes within the three distinct lipoyl domains. We examined a total of 321 sera, including 186 sera from patients with PBC, to test the immunoreactivity of pMIT3. Of 186 sera from patients with PBC, 152 sera (81.7%) reacted with recombinant fusion protein of PDC-E2, whereas 171 sera (91.9%) showed positive reactivities when probed by immunoblotting against the recombinant fusion protein expressed from the pML-MIT3 clone. Of 34 PBC sera that did not react with recombinant PDC-E2, 18 sera contained BCOADC-E2-specific AMA and 1 serum possessed only OGDC-E2-specific AMA. We also developed an enzyme-linked immunosorbent assay (ELISA), using affinity-purified recombinant fusion protein of pML-MIT3 clone as the antigen source, to quantify specific AMAs in patients with PBC. None of the 135 control sera from patients with primary sclerosing cholangitis (PSC), chronic autoimmune hepatitis (CAH), systemic lupus erythematosus (SLE), or healthy volunteers showed significant reactivity against pML-MIT3 recombinant fusion protein in the ELISA assay. Our results indicate that an ELISA using recombinant, cloned autoantigen of pML-MIT3 is a powerful and very specific method for the detection of AMA.
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PMID:Use of a designer triple expression hybrid clone for three different lipoyl domain for the detection of antimitochondrial autoantibodies. 870 89

The present study was aimed to examine the protective effects of Sargassum polycystum (Phaeophyceae) alcoholic extract on changes in liver mitochondrial enzymes against acetaminophen induced toxic hepatitis in experimental rats. The levels of protein, lipid peroxide, glutathione (GSH) in mitochondrial fraction, superoxide dismutase (SOD) and catalase (CAT) were also determined. The activities of tricarboxylic acid enzymes such as isocitrate dehydrogenase (ICD), alpha-ketoglutarate dehydrogenase (alpha-KGD), succinate dehydrogenase (SD), malate dehydrogenase (MD), NADH dehydrogenase, and cytochrome-c-oxidase were determined in mitochondrial fraction. The rats intoxicated with acetaminophen showed significant elevation in the levels of lipid peroxides with decreased levels of protein, GSH, SOD, CAT and impaired tricarboxylic acid cycle enzyme activities. The prior oral administration of S. polycystum alcoholic extract showed significant diminution in the severity of toxic hepatitis in acetaminophen-induced rats by maintaining the activities of tricarboxylic acid enzymes with concomitant improvement in the hepatic mitochondrial antiperoxidative status when compared with intoxicated animals. The results obtained in the present study indicate that the protective effects of S. polycystum extract may be due to the presence of some active compounds that are inhibitory against the free radicals generated during lipid peroxidation in acetaminophen induced toxic hepatitis.
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PMID:Antioxidant effect of Sargassum polycystum (Phaeophyceae) against acetaminophen induced changes in hepatic mitochondrial enzymes during toxic hepatitis. 1616 51