Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hepatitis B viral particles (HB-VP) were purified from sera of chronic hepatitis B surface antigen (HBsAg) positive carriers by consecutive isopycnic and rate-zonal sedimentation in sucrose gradients. Their immunological properties [HBsAg, hepatitis B core antigen (HBcAg) and hepatitis B e-antigen (HBeAg) activities] were examined by a radioimmunoassay based upon the classical "sandwich principle". A double antibody specificity radioimmunoassay (DAS-RIA) was then developed to determine whether envelope proteins (HBsAg) with binding activity for polymerized human serum albumin (pHSA-BA) were associated with core-specific antigenicities (HBc/HBeAg). An e-antigen activity cosedimenting with intact HB-VP (negative for HBcAg reactivity) was detected in association with HBsAg and receptors for pHSA. The presence of HBcAg-specific determinant(s) on HBeAg molecules was also indicated by DAS-RIA. So, we postulated that such hepatitis B virion (HBV) specific molecules are involved in immune complexes with anti-HBc as antibodies in sera of patients with chronic HBV infection. To define the significance of these molecular forms in HB-VP morphogenesis, we studied the effects of a mild treatment with a chaotropic salt, NaSCN, on HB-VP-rich fractions (DNA polymerase positive). A small mol. wt HBeAg derived from HB-VP by dissociating treatment was detected. We found that core-specific determinants (HBe/HBcAg) were bound to large surface proteins (HBsAg) with pHSA-BA and therefore probably contained the pre-S sequence. The selective release from HB-VP of such molecular forms, which could be a product of the major S-region transcript, suggests that they may be components of complete virions.
...
PMID:Demonstration of a firm association between hepatitis B surface antigen proteins bearing polymerized human albumin binding sites and core-specific determinants in serum hepatitis B viral particles. 241 11

The effects of suramin, an antiparasitic agent, upon in vitro hepatitis B surface antigen production by the human hepatoma cell line PLC/PRF/5 and hepatitis B virus associated DNA polymerase activity in the serum of a chronically infected patient were examined. Treatment with suramin resulted in decreases in hepatitis B surface antigen production and hepatitis B-virus associated DNA polymerase activity. The decrease in hepatitis B surface antigen production was paralleled by a general decrease in hepatoma cell viability and cellular protein synthesis. Although the inhibitory effects of suramin for hepatitis B virus appear to be nonspecific as demonstrated in these two in vitro systems, the recently announced trial of suramin for the treatment of the acquired immunodeficiency syndrome should afford an unusual opportunity to evaluate the effectiveness of suramin in the treatment of chronic hepatitis B virus infection.
...
PMID:Effects of suramin on in vitro HBsAg production by PLC/PRF/5 cells and hepatitis B virus DNA polymerase activity. 242 68

The binding of polyalbumin to hepatitis B virus (HBV)-associated envelope epitopes has been studied by means of a radioimmunoprecipitation technique. HBV particles were purified from the sera of chronic hepatitis B surface antigen (HBsAg) carriers and labelled through the endogenous HBV-DNA polymerase reaction. Human albumin, polymerized through glutaraldehyde cross-linking, was able to precipitate (100%) labelled HBV at concentrations of 31.2 and 62.5 micrograms/ml, in contrast to monomeric albumin (HSA). This event was further confirmed by immune electron microscopy. The addition of anti-HSA to the mixture HBV plus polyalbumin gave a 100% precipitation in a wide dilution range (15.6-500 micrograms/ml). The binding of polyalbumin (31.2 micrograms/ml) to virions was strongly inhibited (up to 98%) when preincubating with antibody to a glycosylation-dependent preS2 epitope on HBV. The same was accounted (up to 99%) for polyvalent IgG anti-HBs. However, antibodies to the group 'a' and subtype 'd' determinants, as well as anti-preS1 region antibodies, inhibited weakly polyalbumin binding to HBV. The binding site of the inhibitory antibody overlaps probably with neutralizing epitopes. Our findings support the hypothesis that albumin binding plays an important role in the viral life cycle.
...
PMID:Inhibition of albumin binding to hepatitis B virions by monoclonal antibody to the preS2 domain of the viral envelope. 245 8

In ten carriers positive for chronic hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and DNA polymerase, the authors investigated the efficacy of the combination therapy consisting of glycyrrhizin withdrawal and human fibroblast interferon (locally produced). Glycyrrhizin was given for four weeks and was stopped without tapering off the dose. Human fibroblast interferon was given continuously. Thirty-six weeks after the end of this treatment, three of the ten patients were HBeAg negative but not anti-HBe positive, and in one of these three DNA polymerase became undetectable. Another patient showed a loss of DNA polymerase with HBeAg. Transaminase levels decreased in nine of the patients. Glycyrrhizin appeared to act as an antiviral agent in four patients and had a corticoid-like effect in three. DNA polymerase decreased remarkably after interferon administration, and serum transaminase levels increased. No side effects were reported in patients receiving glycyrrhizin. In contrast, almost all patients receiving human fibroblast interferon had influenza-like symptoms, which, although initially severe, decreased with subsequent injections of interferon. Thus this combination therapy seems safe and effective.
...
PMID:Combination therapy of glycyrrhizin withdrawal and human fibroblast interferon for chronic hepatitis B. 249 83

The effect of interferon (IFN) on hepatitis B virus (HBV) replication was investigated in a stable expression system, using HepG2 cells transfected with recombinant HBV DNA. IFN was found to cause a marked reduction in the levels of both minus and plus strands of HBV DNA from core particles in the cytoplasm. Neither HBV DNA from virus particles nor the HBV surface antigen in the culture medium primarily underwent change in quantity by treatment with IFN, as was also found for HBV mRNAs and the HBV core antigen/HBV e antigen in the cytoplasm. IFN exerted no influence on HBV DNA synthesis by endogenous DNA polymerase in the core particle fraction. From these findings, it would appear that IFN inhibits HBV replication by blocking some step in the pregenome RNA-primed assembly of core particles.
...
PMID:Interferon inhibits hepatitis B virus replication in a stable expression system of transfected viral DNA. 249 31

A flow cytometric method to analyze phenotypes of proliferative cells was developed using human leukemic cell line MOLT 4. A nuclear protein, DNA polymerase alpha (pol alpha), was selected as a marker for proliferative cells, and Leu3a molecule as a cell-surface antigen phenotype marker of the cells. The procedure involved the simultaneous use of fluorescein-conjugated anti-pol alpha antibody, developed by us, and commercially available phycoerythrin-conjugated anti-Leu3a antibody. The optimal fixative for both proteins was phosphate-buffered 2% paraformaldehyde. The pol alpha-positive population in logarythmically growing MOLT 4 cells was estimated, by flow cytometry, to be ca. 95%. A sharp flow cytometry histogram with a strong pol alpha-linked fluorescence was observed. On the other hand, the pol alpha-positive population in the saturated culture was ca. 70%, with weaker pol alpha-linked fluorescence. Thus, the population of pol alpha-positive cells and the amount of pol alpha in cells was dependent on the cell density of the culture. In contrast, ca. 90% Leu3a-positive populations with similar flow cytometry histograms were seen in either growing or saturated states, suggesting that expression of Leu3a was independent of cell density. The flow cytometric method using fluorescein isothiocyanate-conjugated anti-pol alpha antibody is useful for detecting proliferative fractions of free tumor cells, such as leukemic cells. Furthermore, analysis of the phenotype of the proliferative or non-proliferative cells became easier by simultaneous labeling with antibodies against pol alpha and phenotype-specific proteins.
...
PMID:Expression of DNA polymerase alpha and Leu3a molecules in growing and saturated cultures of human leukemic cells: phenotype analysis of proliferative cells by flow cytometry. 251 70

Twenty-three staff members serving in a hemodialysis unit were exposed accidentally to needlestick contaminated with blood containing hepatitis B surface antigen and hepatitis B e antigen, as well as high levels of DNA polymerase activity (greater than 100 cpm). They received hepatitis B vaccine (20 micrograms) simultaneously with hepatitis B immune globulin (5 ml, 200 IU per ml) within 48 hr after the exposure, and the vaccination was repeated at 1 and 3 months. The protective efficacy was compared with that in a past study in the same unit in which 33 members were given hepatitis B immune globulin alone within 48 hr after the exposure to blood with similarly high levels of DNA polymerase activity. No differences were noted in age or sex between the staff members who were vaccinated and those who were not, nor were there any differences between their inocula in the titers of hepatitis B virus markers. During 12 months after the accident, only one (4%) of the 23 vaccinated members contracted hepatitis B virus infection, at a frequency significantly lower than 11 (33%) of the 33 members who did not receive vaccine (p less than 0.02). These results indicate that hepatitis B vaccine, when given in combination with hepatitis B immune globulin, is efficacious for postexposure immunoprophylaxis of accidental infection.
...
PMID:Combined hepatitis B immune globulin and vaccine for postexposure prophylaxis of accidental hepatitis B virus infection in hemodialysis staff members: comparison with immune globulin without vaccine in historical controls. 252 91

Hepatitis B surface antigen, DNA polymerase, and hepatitis B virus DNA have been sought in the tears of 72 patients. These markers were detected in a high percentage of hepatitis B carriers, which proves the presence of hepatitis B virus in the tears and raises the question of its eventual transmission in this way. The severity and extreme contagiousness of hepatitis B together with the increasing number of virus carriers justify systematic sanitary rules among ophthalmic clinicians and staff, but vaccination remains the best mean of limiting the spread of the disease.
...
PMID:Detection of HBs antigen, DNA polymerase activity, and hepatitis B virus DNA in tears: relevance to hepatitis B transmission by tears. 273 Aug 53

A rat hepatoma cell line (Q7) of Morris hepatoma origin was transfected with a construct containing the tandem dimer genome of human hepatitis B virus (HBV) and the neomycin-resistant selection marker. The culture medium of several neomycin-resistant single-cell clones was found to accumulate high levels of secreted HBV surface antigen and core-related e antigen. HBV-specific replication intermediates, including relaxed circular and single-stranded DNA with a minus-strand polarity, could be found in both the intracellular fraction and the extracellular culture medium by the Southern blot procedure. One of these clones, designated Q7 HBV-21, was characterized in further detail. DNA polymerase activity was present in the virus particles produced by Q7 HBV-21 cells. Characteristic transcripts of HBV, including the 3.5-, 2.5-, and 2.1-kilobase mRNA as well as a core-gene-related transcript of 2.2 kilobases could be detected. Electron microscopic examination of the conditioned medium from Q7 HBV-21 cells identified 42-nm Dane-like particles as well as 22-nm subviral particles with a spherical or filamentous shape. This Q7 HBV-21 cell line has been maintained in the absence of neomycin for 1 year without losing the properties of HBV DNA replication and Dane-like particle production. Our results strongly suggest that the species barrier of HBV infection is at an early step of viral absorption onto or penetration into the target hepatocytes. This nonhuman system for HBV production in culture could be used to complement the human HepG2 system.
...
PMID:In vitro propagation of human hepatitis B virus in a rat hepatoma cell line. 276 28

A total of 848 household contacts of 285 hepatitis B surface antigen (HBsAg) chronic carriers were included in a prospective study. Of the total number of contacts negative for hepatitis B virus (HBV) markers at baseline, 330 relatives of 145 HBsAg carriers were observed over a mean period of 20.1 months. Among all household contacts, 284 (33.5%) were found positive for at least one HBV marker. The prevalence of HBV markers was significantly higher among the contacts of more than one HBsAg carrier (75.9%) than among those with only one (26.0%) (P less than .001). The presence of hepatitis B e antigen (HBeAg), specific HBV-DNA polymerase (HBV-DNAp), HBV-DNA, and polymerized human serum albumin (pHSA-R) in the index case was associated with a significantly higher incidence of HBV markers among household contacts. During the follow-up, the number of household contacts initially negative for HBV markers who became infected was found to be in direct relation to the presence of HBeAg, HBV-DNAp, HBV-DNA and pHSA-R in the index case.
...
PMID:A dynamic study of the intrafamilial spread of hepatitis B virus infection: relation with the viral replication. 277 47


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---