Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019163 (hepatitis B)
 38,309 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An enzyme immunoassay for detection of hepatitis B surface antigen based on the use of 3 monoclonal antibodies (mAbs) was developed: an IgM as capture and 2 IgG1 for detection. The system biotin-streptavidin was compared with direct conjugation of mAbs to peroxidase and was preferred because of its higher signal to noise ratio. The possibility of simultaneous addition of human serum and biotin-mAb was discarded because of an evident prozone effect with some sera containing high HBsAg levels. The conjugation of biotin to IgG1 mAbs through a spacer arm (amidocaproyl) and the use of a highly sensitive substrate (tetramethylbenzIdine) improved the assay detection limit by about 10 times.
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PMID:A double sandwich monoclonal enzyme immunoassay for detection of hepatitis B surface antigen. 831 26

A method was developed for the analysis of heterogeneity in antigen polypeptides in individual sera. Polypeptides in sera were adsorbed by polystyrene beads coated with antibody in wells of a microplate. They were dissociated with a small volume of elutant, and transferred to slots on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Polypeptides separated on gel were then immunoblotted with antibodies labeled with horseradish peroxidase. The method was applied to analyze different populations of hepatitis B surface and e antigen polypeptides in sera from carriers of hepatitis B virus. Applicability to mass-scale and high sensitivity of the method would allow surveys of heterogeneous antigen polypeptides in serum for any biological significance.
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PMID:SDS-PAGE after micro-affinity adsorption for analysis of heterogeneous antigen polypeptides in individual sera. 842 66

The uptake and distribution of phosphorothioate oligodeoxynucleotides by human cells were studied using 35S-labeled 28-mer phosphorothioate oligodeoxycytidine [S-(dC)28]. Accumulation of intracellular S-(dC)28 was found to be higher in the carcinoma cells (grown in monolayers) than in the leukemia cells (grown in suspension culture). A hepatoma cell line transfected with hepatitis B virus, 2215, was chosen for further studies. The uptake of S-(dC)28 was partially dependent on temperature and energy. The intracellular concentration was significantly higher than that in the medium and the amount accumulated was dependent on the extracellular concentration. It appears that the uptake of S-(dC)28 involves mechanisms of both fluid-phase pinocytosis and adsorptive endocytosis. Neither oligonucleotides nor 5'-phosphorylated nucleotides inhibited S-(dC)28 uptake. Unlike horseradish peroxidase, which was primarily associated with endosomes once it was taken into the cell, S-(dC)28 was found to be present in both nuclear and cytoplasmic fractions. Efflux of S-(dC)28 from the cell was multiphasic; a trapping mechanism that could be due to a potent interaction of S-(dC)28 with cellular proteins was implicated. This trapping mechanism could be responsible for the lack of biological activity such as cytotoxicity and antisense activity of phosphorothioate oligodeoxynucleotides in some human cells.
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PMID:Cellular pharmacology of phosphorothioate homooligodeoxynucleotides in human cells. 842 68

A double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) is described for the detection of Plasmodium falciparum antigen. The test is based on an immunoglobulin (Ig) M capture monoclonal antibody on the solid phase and an IgG monoclonal antibody conjugated to peroxidase. The simple test takes about 2.5 h to complete and, because it uses whole blood with no prior treatment, it is possible to process batches of 50-100 samples simultaneously. The test is specific to P.falciparum and has a sensitivity close to that usually achieved with Giemsa-stained blood films. The reagents employed are stable at refrigerator temperatures for over 6 months, and as the test is compatible with human immunodeficiency virus and hepatitis B surface antigen ELISAs it could be suitable for blood transfusion screening.
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PMID:The development and validation of a simple antigen detection ELISA for Plasmodium falciparum malaria. 846 87

Horseradish peroxidase was activated by periodate oxidation of the carbohydrate moiety and then modified by the covalent attachment of alpha-N,N-bis[carboxyethyl]lysine (CM-Lys) by reductive alkylation using sodium cyanoborohydride. The resultant CM-Lys peroxidase was charged with nickel ions and then used as a specific labeling reagent for histidine-tagged recombinant proteins. This labeling method was effective for proteins that are soluble or insoluble in the absence of chaotropic agents. The labeled proteins were very effective in direct sandwich enzyme-linked immunosorbent assay for detecting antibodies against the protein in sera as demonstrated by assays for antibodies to such diverse viral proteins as hepatitis B surface and core proteins, hepatitis C core and helicase protein (NS3), and retroviral core proteins.
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PMID:Use of alpha-N,N-bis[carboxymethyl]lysine-modified peroxidase in immunoassays. 853 95

We have developed a sensitive and quantitative assay for hepatitis B virus (HBV) DNA in serum or plasma in which PCR and then microtiter hybridization analysis are used. Assay of HBV DNA in serum or plasma is important for demonstrating viral replication, indicating and monitoring antiviral therapy, determining the infectivities of virus carriers, and ensuring the safety of blood products. Under optimum conditions PCR can amplify one HBV DNA molecule to 10(8) copies, but detection of this amount of DNA still requires hybridization with labelled probes or a nested PCR. We labelled one strand of the PCR product with a biotinylated primer. The double-stranded amplicon was incubated in streptavidin-coated microplate wells. The nonlabelled strand was removed after denaturation of the double-stranded DNA with alkali, and the bound strand was hybridized with a peroxidase-coupled single-stranded probe. The amount of bound peroxidase was measured in a luminometer. Four picograms of amplicon was detectable in this system, whereas conventional ethidium bromide staining requires a 1,000 times higher amplicon concentration. The performance of the new assay was compared with those of nested PCR and a PCR system that uses a digoxigenin label, hybridization to a solid-phase adsorbed probe, and colorimetric detection. The chemiluminescence assay was found to be almost as sensitive as nested PCR and approximately five times more sensitive than the colorimetric test.
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PMID:Quantitative assay of PCR-amplified hepatitis B virus DNA using a peroxidase-labelled DNA probe and enhanced chemiluminescence. 881 75

A simple system to detect polymerase chain reaction (PCR) amplification products was developed. This detection method has the sensitivity and the specificity of nested primer PCR amplification or Southern blot hybridization of PCR product. Digoxigenin-labeled PCR products were hybridized with a biotinylated probe in liquid phase and captured on to microtiter wells coated with antidigoxigenin followed by detection with streptavidin-peroxidase. The sensitivity of this assay for the detection of hepatitis A virus, hepatitis B virus, and hepatitis C virus is equal to that of existing nucleic acid detection systems.
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PMID:Sequence-specific, single-primer amplification and detection of PCR products for identification of hepatitis viruses. 888 45

Hepatitis B e antigen (HBeAg) polypeptide in the circulation (p17e) is composed of ten amino acids (aa) coded for by the precore region and 149 aa by the core gene of hepatitis B virus. A monoclonal antibody (Y0583A) was raised against the N-terminal ten amino acids (SKLCLGWLWG) encoded by the precore region. The binding of Y0583A with a panel of 203 decapeptides on multipins, which covered the precursor of HBeAg polypeptide made of 212 aa shifting by one aa, recognized an epitope sequenced LGWLWG representing the C-terminal six aa coded for by the precore region. This HBeAg epitope was not readily accessible on HBeAg in serum, but it became exposed and bound with Y0583A by treatment with 0.2 N NaOH. Using Y0583A, an enzyme-linked immunosorbent assay was developed for specific determination of HBeAg. The test sample was incubated with the monoclonal antibody to an HBeAg determinant encoded by the core gene (904) that had been immobilized on a solid support. Captured HBeAg was treated with 0.2 N NaOH, neutralized and released into the fluid phase. The reactant was then tested for a sandwich between monoclonal antibody (C33) to the C-terminus of the HBeAg polypeptide immobilized on a solid support and Y0583A labeled with horseradish peroxidase.
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PMID:A monoclonal antibody against a hepatitis B e antigen epitope borne by six amino acids encoded by the precore region. 938 11

The activity of the enzymatic activity of the preparations of IgG1, IgG2 and IgG4, isolated from the blood of patients with acute virus hepatitis B and chronic viral hepatitis C resulting in cirrhosis, was studied. The blood samples were found to have DNAase activity significantly exceeding that of immunoglobulins isolated from the blood sera of healthy donors, as well as peroxidase, oxidase and esterase activities, whose level did not significantly differ from those of the donor blood sera. The interaction of IgG preparations with the cations of different metals was studied. The study revealed that the addition of CuSO4 solution at the final concentration of 4.7 x 10(-5) M to the blood samples led to a significant increase in activity in comparison with the initial one (on the average, 7.8 +/- 2.97 times) in all 14 samples. The activity thus observed was partially inhibited by the addition of the solution of staphylococcal protein A. As noted in the course of this study, high DNAase and peroxidase activities of Ig were most frequently observed in patients with cirrhosis of the liver. The difference in the levels of IgG activity between patients with cirrhosis of the liver and patients with virus hepatitis, but no signs of cirrhosis, is not significant.
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PMID:[The enzymatic activity of IgG preparations in viral hepatitis]. 978 8

In areas where hepatitis B virus (HBV) is prevalent, HBV carriers negative for hepatitis B surface antigen (HbsAg) by enzyme-linked immunosorbent assay (ELISA) have been reported. Moreover, even after screening donor blood for HbsAg and hepatitis B core antibody (HBcAb), post-transfusion hepatitis B continues to occur, though with a decreasing frequency. Therefore, screening tests far more sensitive for detecting HBsAg than those currently available are needed. We developed a highly sensitive method for HBsAg detection. It is based on the recognition of peroxidase activity through measuring the formation of stable nitroxide radical with electron spin resonance (ESR) spectroscopy in the presence of hydrogen peroxide, p-acetamidophenol (p-AP), and 4-hydrazonomethyl-1-hydroxy-2,2,5,5,-tetramethyl-3-imidazoline-3-o xide (HHTIO). A cut-off value was established by testing of 186 healthy adults and 50 HBsAg-positive individuals. The signal to noise (S/N) ratio of less than 1.488 obtained by ESR spectroscopy was considered to be negative and more than 2.181, positive. The p-AP/HHTIO method was found to be 10 times more sensitive than the standard ELISA and reproducibility was excellent. Additional investigations were made on the HBsAg levels in the serum from 26 healthy subjects, in whom cut-off index levels on ELISA were negative but relatively high (range: 0.6 to 1.0); and on 15 patients with non B non C hepatitis. Three of 26 cases and 3 of 15 with non B non C hepatitis were judged to be HBsAg positive. Of these, 5 were found to be positive for HBV DNA by polymerase chain reaction (PCR). It was shown in this study that the p-AP/HHTIO method is practical and useful in screening HBV carriers because of the sensitivity in HBsAg detection, which is comparable to PCR analysis.
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PMID:Highly sensitive hepatitis B surface antigen detection by measuring stable nitroxide radical formation with ESR spectroscopy. 984 Jul 38


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