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

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

In a study of the distribution of e-antigen and anti-e in subjects whose blood was positive for hepatitis B surface antigen (HBsAg), patients with acute hepatitis B who were tested during the incubation period were all e-antigen-positive but after the onset of illness e-antigen was detected in only 11%. Persistence, and in some instances reappearance of e-antigen in those who became long-term carriers of HBsAg was associated with high titres of HBsAg. There was a high incidence of e-antigen in those conditions in which cell-mediated immunity may be depressed, including Down's syndrome and chronic renal failure. The majority of HBsAg carries identified as sources of infection were e-antigen-positive. A postive reaction for e-antigen is evidently associated with a defective immune response to hepatitis B virus infection which permits continued replication of virus in liver cells accompanied by high titres of HBsAg, numerous Dane particles and detectable DNA polymerase in the blood with consequently a greater likelihood of transmitting infection. Although it cannot be assumed that anti-e positive carriers of HBsAg are not infective, it may be necessary, in the assessment of passive or active immunization for the control of hepatitis B, to take into account the e-antigen/antibody status of possible sources of infection.
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PMID:e-Antigen: a link between immune response and infectivity in hepatitis B? 73 Oct 22

Hepatitis B core antigen (HBcAg) was purified from Dane particles and from infected hepatocytes. An identical isoelectric pH of 4.0 was determined for labeled preparations of both Dane-derived and liver-derived HBcAg. Unlabeled liver-derived HBcAg demonstrated a lower isoelectric pH of 3.7. Molecular weight determinations by Sepharose 4B column chromatogrpahy revealed that liver-derived HBcAg had a molecular weight of 8.5-9.0 X 10(6) daltons. The sedimentation coeficient of both Dane- and liver-derived HBcAg was found to be 124S. PAGE revealed that iodinated HBcAg derived from Dane particles was very similar in polypeptide structure to HBcAg derived from infected liver tissue. Twelve polypeptides were resolved from Dane core particles, and seven to nine were resolved from liver core particles. Several of the polypeptides in both preparations co-migrated with iodinated hepatitis B surface antigen (HBsAg). However, three polypeptides (mol. wt. 88,000, 79,000 and 59,000) were found in both Dane- and liver-derived HBcAg but not in HBsAg, which suggests that these polypeptides are HBcAg-specific. Endogenous DNA polymerase activity was observed in both Dane- and liver-derived core particles.
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PMID:Biochemical and biophysical properties of hepatitis B core particles derived from Dane particles and infected hepatocytes. 89 38

A high positive correlation was found between e antigen (HBe Ag) and DNA polymerase in hemodialyzed patients with acute hepatitis B, chronic carriers of hepatitis B surface antigen undergoing hemodialysis, and patients with chronic hepatitis. In contrast, the correlation was poor in nonhemodialyzed patients with acute hepatitis. Among the patients with chronic hepatitis, HBe Ag and DNA polymerase were were found mostly in those with aggressive hepatitis and rarely in those with persistent hepatitis. This difference was significant (P less than 0.01) and suggests that the persistence of these antigens may be a factor in the progression of the disease. Our data also indicate that the development of antibodies to HBe Ag (anti-HBe) might be a sign of a favorable prognosis, since 50% of the patients with persistent hepatitis vs. 6% of the patients with aggressive hepatitis were anti-HBe-positive. Inhibitors of DNA polymerase, which are possibly antibodies, appeared regularly after acute hepatitis and were transient. Their presence may be associated with viral replication.
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PMID:e antigen and antibody, DNA polymerase, and inhibitors of DNA polymerase in acute and chronic hepatitis. 91 41

Thirty-nine carriers of hepatitis B surface antigen (HBs Ag) were studied with respect to e antigen and Dane particle-associated DNA polymerase activity and their relation to chronic hepatitis. Most of these individuals were followed for four or five years. A strong correlation between e antigen and DNA polymerase activity was found. Of the 22 e antigen-positive patients, 21 showed polymerase activity; none of the 13 e antigen-negative patients (one of whom had antibody to e antigen) had such activity. Three of four patients who became e antigen-negative after being e antigen-positive showed loss of polymerase activity. An independent clinical evaluation showed a strong correlation between chronic hepatitis and positive reactions in the tests for e antigen and DNA polymerase. The results emphasize the possibility of differentiating between groups of chronic carriers of HBs Ag by testing for e antigen and Dane particle-associated DNA polymerase activity. The differentiation may have important clinical implications.
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PMID:Dane particle-associated DNA polymerase and e antigen: relation to chronic hepatitis among carriers of hepatitis B surface antigen. 93 24

Four patients with chronic hepatitis B infection and chronic active hepatitis were treated with human leukocyte interferon. Three of them had consistently elevated levels of circulating Dane-particle markers, including Dane-particle-associated DNA polymerase activity, hepatitis B core antigen and Dane-particle-associated DNA. Parenteral interferon administration at a dosage between 6.0 X 10(3) and 17 X 10(4) U per kilogram per day was associated with a rapid and reproducible fall in all Dane-particle markers in the three patients. The suppressive effect was transient when the interferon was given for 10 days or less but appeared to be more permanent when administration was prolonged for a month or more. In addition, long-term interferon therapy was associated with a marked fall in hepatitis B surface antigen in two of three patients and a disappearance of e antigen in two of two patients. Interferon may be useful in limiting carrier infectivity or eradicating chronic infection.
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PMID:Effect of human leukocyte interferon on hepatitis B virus infection in patients with chronic active hepatitis. 95 Sep 57

Serum samples of 403 asymptomatic blood donors carrying hepatitis B surface antigen (HB5Ag) were concentrated threefold and tested for e antigen and antibody to e antigen (anti-e) by immunodiffusion. Hepatitis B antigen (HBAg)-associated deoxyribonucleic acid (DNA) polymerase activity was specifically determined by the difference in incorporation of [methyl-3H]thymidine 5' -triphosphate into DNA by an aliquot of centrifuged serum samples after it had been treated either with normal rabbit serum or with rabbit antibody to HBSAg. All of 58 serum samples containing e antigen revealed HBAg-associated DNA polymerase activity, whereas none of 96 samples containing anti-e did. In the remaining 249 samples in which neither e antigen nor anti-e was found, 62 showed specific DNA polymerase activity, although at lower levels than the samples containing e antigen.
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PMID:Hepatitis B antigen-associated deoxyribonucleic acid polymerase activity and e antigen/anti-e system. 96 88

Sera of 103 carriers of hepatitis B surface antigen were assayed for e-antigen and anti-e. Twenty-four were e-antigen-positive, 31 anti-e-positive, and 48 had neither detectable (e-negative). Aminotransferases were elevated in 75% of the e-antigen-positive carriers compared with 25% of e-negative carriers (P less than 0.001) and 13% of anti-e-positive carriers (P less than 0.001). Serum DNA polymerase activity was significantly higher in the e-antigen-positive carriers than in carriers without e-antigen. Dane particles were shown in 10 of 12 carriers with e-antigen, compared with one of 12 e-negative carriers (P less than 0.0003) and none of 12 anti-e-positive carriers (P less than 0.00003). These results suggest that ongoing hepatitis B viral replication is more active in e-antigen-positive carriers than in carriers without e-antigen, a finding that may help explain the high prevalence of chronic active hepatitis described in these individuals.
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PMID:"e" Antigen, Dane particles, and serum DNA polymerase activity in HBsAg carriers. 97 Jul 72

Studies conducted in 1970 and 1971 with heat-inactivated MS-2 serum revealed that this active immunizing procedure was associated with a protective effect, a more attenuated hepatitis B infection and a decreased hepatitis B carrier rate. More recent studies have revealed striking differences in the response of unimmunized and immunized persons following a parenteral exposure to the MS-2 strain of hepatitis B virus. Serial tests for the detection of hepatitis B surface antigen (HBsAg), DNA polymerase activity, serum transaminase (SGOT), antibody to HBsAg (anti-HBs) and antibody to hepatitis B core antigen (anti-HBc) revealed the following findings. In serosusceptible unimmunized persons HBsAg was detectable about 4 weeks after exposure, DNA polymerase activity at about 6 weeks, abnormal SGOT levels at about 8 weeks, anti-HBc at about 8-10 weeks, and anti-HBs usually after 20 weeks. In successfully immunized persons HBsAg, DNA polymerase activity, abnormal SGOT levels, and anti-HBc were not detectable, evidence of a booster response of pre-existing or non-detectable anti-HBs was observed one to two weeks after exposure. Studies by various investigators have revealed that anti-HBs is associated with protection and resistance to reinfection. In contrast, anti-HBc is not protective and does not correlate positively with either resistance to infection or recovery from infection. The availability of sophisticated biophysical and biochemical techniques has enabled several investigators to prepare candidate inactivated hepatitis B vaccines from purified preparations of HBsAg. The successful propagation of hapatitis B virus infection to susceptible chimpanzees has provided an excellent animal model for the evaluation of hepatitis B vaccines. At the present time various investigators are studying the immunogenic and protective effect of the vaccine in these animals. Prospects for the development of a vaccine for the prevention of viral hepatitis type B are encouraging. It is extraordinary that this objective will be achieved in spite of the failure to isolate the etiologic agent in tissue culture.
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PMID:Viral hepatitis type B: propects for active immunization. 120 71

Hepatitis B core antigen, antibody to core antigen, and DNA polymerase activity were measured in sera from a select group of post-transfusion hepatitis B patients who had been followed prospectively following blood transfusion. Preliminary results of this study have revealed (1) that RIA testing of blood would not eliminate but would reduce post-transfusion hepatitis B infections by about 50 per cent; (2) that infection with HB virus is modified or aborted in the presence of pre-existing antibody to HB surface antigen; and (3) that transfusion of blood containing anti-HBs does not increase the risk of post-transfusion hepatitis B. HBc Ag and/or DNA polymerase activity were observed in the sera of all recipients tested who developed liver enzyme abnormalities along HBs Ag and anti-HBc. DNA polymerase activity usually occurred in the early stages of incubation before the transaminase became abnormal, whereas HBc Ag was more often associated with increasing enzymatic evidence of liver damage, suggesting release of core structures from the hepatocytes. The presence of DNA polymerase without detectable HBc Ag may be due to the presence of intact Dane particles in the sera, preventing recognition of the core antigen. No serological evidence of hepatitis B was observed in the sera of 24 other recipients who developed abnormal transaminases. Immunoelectron microscopy of these same sera revealed evidence of exposure to hepatitis A antigen following transfusion in at least two recipients.
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PMID:Hbc ag, anti-HBC, and DNA polymerase activity in transfused recipients followed prospectively. 123 76

Two populations of Dane particles were isolated from the plasma of individuals carrying hepatitis B surface antigen. These populations had densities in CsCl of 1.22 and 1.20 g/ml. Endogenous DNA polymerase activity was found to be associated only with the heavier of these two populations. Using a positive stain, electron microscopic examination of these particles suggested that the heavier the particle contained nucleic acid in its core whereas the lighter particle appeared empty. Cores isolated from Dane particles with densities of 1.22 and 1.20 g/ml banded in CsCl at densities of 1.36 and 1.30 g/ml, respectively. Endogenous DNA polymerase activity was associated only with the higher density core particles.
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PMID:Demonstration of subpopulations of Dane particles. 125 63


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