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)

A controlled trial has been undertaken to evaluate adenine arabinoside in the treatment of hepatitis B surface antigen-positive chronic liver disease. Thirteen patients (7 hepatitis B virus DNA polymerase and hepatitis B e antigen-positive, 6 DNA polymerase negative and hepatitis B e antibody-positive) were treated with adenine arabinoside. Eleven comparable patients served as controls, and follow-up was for 6 mo. In the 7 hepatitis B e antigen-positive patients, adenine arabinoside produced a fall in DNA polymerase activity during treatment. When this effect was sustained, it was followed by a loss of e antigen (3 patients). Hepatitis B surface antigen concentrations and aspartate transaminase levels fell significantly at 6 mo (p less than 0.05) in the treated group compared with controls. In the hepatitis B e antibody-positive patients, adenine arabinoside treatment produced no significant change in hepatitis B surface antigen concentrations or aspartate transaminase levels at 6 mo as compared with controls. Adenine arabinoside would appear to reduce either transiently or permanently, hepatitis B virus replication, and it may therefore be useful in reducing the infectivity of some carriers of this virus. In the dose used, adenine arabinoside was ineffective in clearing hepatitis B surface antigen from the serum and eradicating hepatitis B virus from the liver, but combination with other antiviral or immunostimulant agents may enhance its therapeutic effectiveness.
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PMID:Adenine arabinoside therapy in HBsAg-positive chronic liver disease: a controlled study. 700 10

Hepatitis B virus (HBV) of man has several characteristics that distinguish it from viruses of other groups. These include its ultrastructure, viral DNA size and structure, a virion DNA polymerase which repairs a single-stranded region in the viral DNA, liver tropism, character of persistent infection, and association with hepatitis and hepatocellular carcinoma. Recently three other viruses have been found in other animal species that appear to share these characteristics although the viruses are not identical. HBV, Woodchuck hepatitis virus (WHV), ground squirrel hepatitis virus (GSHV), and duck hepatitis virus (DHV) appear to be members of a new virus group that might be designated the Hepadna virus group. Genetic variation among hepatitis B viruses includes the antigenic variation in the surface antigen (HBsAg) which constitutes the known HBsAg subtypes. There is also frequent variation in DNA base sequence among HBVs isolated from different patients.
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PMID:Genetic variation among hepatitis B and related viruses. 701 20

Two patients referred for cancer chemotherapy were found to be chronic, asymptomatic hepatitis B surface antigen (HBsAg) carriers. They had normal serum aminotransferase levels, but their sera were positive for HGsAg and antibody to hepatitis B e antigen. Both patients developed acute, icteric hepatitis within 3 months of starting cycled chemotherapy. In both cases, the disease seemed to be caused by a recurrence of type B hepatitis; it was accompanied by a marked increase in HBsAg titer and the appearance of hepatitis B virus DNA and DNA polymerase in the serum. One patient had a second episode of acute hepatitis after a second course of chemotherapy, but both patients ultimately recovered and became seronegative for HBsAg. Thus, it seems that cancer chemotherapeutic agents can reactivate type B hepatitis in asymptomatic HBsAg carriers. This reactivation is most likely due to an increase in hepatitis B virus synthesis followed by a rebound in host immune responses to hepatitis B virus infection when therapy is stopped. Such a phenomenon could have important implications for the therapy of chronic hepatitis B virus infection.
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PMID:Reactivation of chronic hepatitis B virus infection by cancer chemotherapy. 706 60

We report a prospective study on infants born to hepatitis B surface antigen (HBsAg) carrier mothers to estimate the incidence of perinatal transmission of HBV and HBV-associated delta agent in Northern Italy. The risk of infection to the infant was related to the presence of the HBe antigen-antibody system, HBV-specific DNA polymerase activity and antibody to delta in maternal sera, and to the titer of anti-HBe in babies at birth. The data of this study indicate: 1. Babies born to HBsAg carrier mothers with HBeAg in serum are at extremely high risk of acquiring HBV infection and of developing a chronic carrier state, whereas those born to anti-HBe-positive mothers are at a lower (P less than .01) yet consistent risk of infection. 2. HBs antigenemia is usually prolonged and symptomatic in babies born to HBeAg-positive mothers while being self-limited and asymptomatic in babies born to anti-HBe-positive mothers. 3. DNA polymerase activity in maternal serum appears to be the most sensitive marker predicting HBV transmission to the infant since it was detected in all the HBeAg-positive mothers and also in two anti-HBe-positive mothers and in one HBeAg/anti-HBe-negative mother who transmitted infection to their babies. 4. High titers of anti-HBe (up to 1:103) do not prevent HBV infection. 5. Vertical transmission of delta infection seems to occur only in circumstances that permit perinatal transmission of HBV infection.
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PMID:Perinatal transmission of the hepatitis B virus and of the HBV-associated delta agent from mothers to offspring in northern Italy. 706 8

Solid-phase radioimmunoassays for woodchuck hepatitis virus (WHV) surface antigen (WHsAg) and antibody to it (anti-WHs) were developed. The test for WHsAg could detect as little as 10 ng/ml. In both tests it was necessary to employ radiolabeled WHsAg instead of anti-WHs as the probe because the latter appeared to be labile to the conditions of labeling. The tests were used to characterize naturally acquired and experimental WHV infections of woodchucks. Forty-three of 72 wild-caught woodchucks had serological evidence of WHV infections; 16 of these resulted in chronic infection, and the remainder were self-limiting. All chronically infected animals were positive for WHsAg and DNA polymerase activity. During 3 years of observation, 11 of the 16 WHsAg-positive animals and 3 of the 27 anti-WHs-positive animals, but none of the 21 uninfected animals developed hepatocellular carcinoma. Seroconversion, possibly resulting from infection with WHV, was documented in a chimpanzee inoculated with WHV. An immune adherence hemagglutination test for WHsAg was also developed by using anti-WHs of chimpanzee origin as a reagent, but the test was not useful for detecting anti-WHs of woodchuck origin because of the lability of the latter.
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PMID:Natural and experimental infection of woodchucks with woodchuck hepatitis virus, as measured by new, specific assays for woodchuck surface antigen and antibody. 707 21

The purpose of this study was to examine the association of circulating viral markers with ongoing liver disease in chronic hepatitis B virus infection. Hepatitis B e antigen (HBeAg) was significantly more likely to be associated with abnormal alanine aminotransferase (ALT) activity than was anti-HBe in a group of 102 HBsAg carriers (p less than 0.0001). Within this group, 57 carriers were analyzed for HBeAg, DNA polymerase, and hepatitis B surface antigen (HBsAg) titer, and the relation of each with abnormal ALT was determined. Both HBeAg and elevated DNA polymerase were much more likely to reflect abnormal ALT (p less than 0.00001 and 0.0006, respectively) than did HBsAg titer. Unlike previous studies, higher titers of HBsAg would not be demonstrated in healthy carriers when compared to HBsAg carriers with chronic elevation of ALT; nor were differences in titer appreciated between chronic active and chronic persistent hepatitis. The potential significance of these findings is discussed.
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PMID:The relationship of hepatitis B e antigen, DNA polymerase activity, and titer of hepatitis B surface antigen with ongoing liver injury in chronic hepatitis B virus infection. 709 Nov 31

The epidemiology of Hepatitis A virus (HAV) and hepatitis B virus (HBV) infection was studied in a northern Canadian Inuit (Eskimo) settlement. Sera from 720 of the 850 inhabitants of Baker Lake, Canada, were tested for markers of HAV and HBV infection. Anti-HAV was present in 71% of the residents and its prevalence increased with age. Serologic evidence of HBV infections was found in 27% of residents. The prevalence increased with age, being uncommon under the age of 20 (6%) and almost universal over the age of 60 (93%). Among the 29 hepatitis B surface antigen (HBsAg) carriers identified, all were adults, all had low levels of HBsAg, and all were negative for hepatitis B e antigen (HBeAg) and DNA polymerase but positive for antibody to HBeAg. These data demonstrate a high prevalence of HAV and HBV infection in this population. Further, they suggest that a dramatic decrease in the transmission of HBV infection has occurred over the past 20-30 years.
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PMID:Hepatitis virus infection in an isolated Canadian Inuit (Eskimo) population. 716 96

8 children, known to have been hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) positive for more than 6 months and with chronic active hepatitis on biopsy, received 2.5 mg levamisole/kg/day, 2 days a week for 6-18 months. In 6 of the 8 children transaminases normalized within 4-18 months of therapy, with seroconversion to antibody to HBeAg (anti-HBe) and disappearance of HBV-DNA polymerase from serum and of hepatitis B core antigen (HBcAg) from liver. In these cases liver biopsies taken after treatment showed histological regression to chronic persistent hepatitis. Two distinct patterns of response to levamisole were noted: patients having higher pretreatment transaminase levels and lower expression of HBcAg in the liver showed an early transaminase normalization and anti-HBe seroconversion with therapy, while in patients with less active disease and more diffuse HBcAg positivity in pretreatment liver biopsies, longer treatment periods were necessary to achieve these effects. Our results suggest that long-term levamisole therapy may be beneficial in HBeAg-positive chronic hepatitis type B.
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PMID:Virological changes in chronic hepatitis type B treated with levamisole. 717

Twenty-five patients with chronic type B hepatitis documented by liver biopsy were followed for 1 to 6 years with serial measurements of aminotransferase levels, hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) and antibody (anti-HBe), and hepatitis B virus DNA polymerase. Initially, all were positive for HBsAg and HBeAg and had elevations in serum aminotransferases. In follow-up, only one lost HBsAg reactivity. In 13, however, elevated aminotransferase levels spontaneously fell to normal and have remained normal. These 13 also had a seroconversion from HBeAg to anti-HBe, and all became negative for serum DNA polymerase. Most had a fall in HBsAg titer. This seroconversion occurred concurrently with or several months before the fall in aminotransferase levels. In contrast, the 12 persons who remained HBeAg positive continued to have elevated aminotransferase levels. All 10 of these patients who were initially positive for DNA polymerase remained positive. These data suggest that many patients with chronic type B hepatitis eventually have a spontaneous remission in clinical and biochemical evidence of active disease, usually heralded or accompanied by the disappearance of HBeAg and DNA polymerase.
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PMID:Seroconversion from hepatitis B e antigen to antibody in chronic type B hepatitis. 723 15

A soluble DNA polymerase was purified 8,000-fold from hepatitis B surface antigen positive serum. The molecular weight of the enzyme by gel filtration was about 1.60 X 10(5), the sedimentation coefficient was 5.5S, the apparent Km for dTTP was 4 micrometer, the optimum pH in the presence of Mg2+ was 9.2, and the pl was 4.7. The enzyme was found in HBsAg-positive sera and required an external primer for activity. The properties of the DNA polymerase were different from hepatitis B virus particle enzyme and from vertebrate and bacterial DNA polymerases. The prevalence of this enzyme did not correlate with HBeAg or particle DNA polymerase in HBsAg-positive sera.
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PMID:Properties of soluble DNA polymerase from sera of hepatitis B virus carriers. 724 Oct 96


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