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)

9-beta-D-Arabinofuranosyladenine (ara-A), 1-beta-D-arabinofuranosylcytosine (ara-C), and their 5'-triphosphates (ara-ATP and ara-CTP) were tested for ability to inhibit the hepatitis B virus (HBV)-associated deoxyribonucleic acid (DNA) polymerase. Ara-C did not inhibit the HBV DNA polymerase at the concentrations tested, ara-A did so by 50% at a concentration of 30 mM, with the inhibition noncompetitive with respect to deoxyadenosine 5-triphosphate (dATP). Ara-ATP and ara-CTP inhibited the DNA polymerase test competitively with respect to dATP and dCTP, respectively. Both compounds were also active after initiation of the DNA polymerase reaction. The inhibition caused by ara-ATP and ara-CTP was shown to be reversible, with no evidence that ara-ATP or ara-CTP was incorporated into the HBV DNA.
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PMID:Inhibition of hepatitis B virus deoxyribonucleic acid polymerase by the 5'-triphosphates of 9-beta-D-arabinofuranosyladenine and 1-beta-D-arabinofuranosylcytosine. 616 46

The effect of several antiviral drugs on the reactivation of herpes simplex virus type 1 in explant cultures of latently infected mouse trigeminal ganglia was investigated. Phosphonoacetate and phosphonoformate, which act directly on the virus-induced DNA polymerase, require a drug concentration of 400 micrograms/ml for the inhibition of virus reactivation in latently infected ganglia. Arabinosyladenine and arabinosyladenine monophosphate, which are phosphorylated to triphosphates by cellular enzymes and inhibit virus synthesis either by blocking the DNA polymerase or by incorporation into viral DNA, require a concentration of only 100 micrograms/ml for the inhibition of the reactivation process. Drugs that are phosphorylated by the virus-induced thymidine kinase, such as acyclovir, arabinosylthymine, bromovinyldeoxyuridine, and three fluorinated pyrimidine nucleosides require the lowest drug concentrations for complete inhibition of virus reactivation in latently infected ganglia explant cultures. Our data suggest that the inhibition of virus reactivation is dependent not only on drug concentration, but also on the number of latently infected neurons in the ganglia.
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PMID:Effect of eight antiviral drugs on the reactivation of herpes simplex virus in explant cultures of latently infected mouse trigeminal ganglia. 620 91

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

Five male patients with HbsAg-positive liver disease were treated with ara-A at dosages ranging between 5 mg and 10 mg/kg/day for five days. Before treatment, all of them had detectable DNA polymerase activity and HbeAg in their sera. The five-day course of the drug resulted in a rapid fall in DNA polymerase activity in every patient, the effect being dose-dependent. The amount of circulating Dane particles also decreased simultaneously, or with a short time lag, with the fall of the enzyme activity. The following decrease in HBeAg concentration was observed in all patients, and it was also noteworthy that antiHBe response was found in two of the five. HBsAg titers were significantly diminished in two patients. In the present series of ara-A treatment, these effects were temporary in two patients, while, in the remaining three, they lasted for two to three months. Ara-A had no serious side effects at dosages of 10 mg/kg/day or less, and can thus be counted among the valuable therapeutic drugs against chronic HBV infection.
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PMID:Evaluation of the antiviral effects of adenine arabinoside on chronic HBV infection. 710 92

The effect of the DNA polymerase inhibitors adenine 9-beta-arabinofuranoside (ara-A), cytosine 1-beta-arabinofuranoside (ara-C), and aphidicolin on X-radiation sensitivity was studied in a group of exponentially growing squamous cell carcinoma cell lines. The tumour cell lines varied in radiation sensitivity, with D0 (radiation sensitivity) values ranging from 1.0 to 3.9 Gy. The addition of non-toxic concentrations of ara-A 30 min before irradiation and removal 30 min after irradiation potentiated cell killing in five of eight cell lines. Four of these five responsive cell lines were relatively radioresistant lines, having D0 > 2.0 Gy. One of the cell lines was more radiosensitive (D0 = 1.4 Gy). Ara-A was also effective in potentiating killing in the radioresistant cell lines even when added 60 min after irradiation. Pre- or post-treatment with ara-A had no effect on X-ray sensitivity of the other three relatively sensitive cell lines (D0 ranging from 1.0 to 1.3 Gy). Both ara-C and aphidicolin were effective in potentiating X-ray sensitivity in JSQ-3, a relatively resistant cell line that was sensitized by ara-A treatment, but they had no effect on the X-ray sensitivity of SCC-61, a relatively radiosensitive cell line that was insensitive to ara-A effects on X-ray response. At the concentrations used, the polymerase inhibitors were equally effective in inhibiting DNA synthesis.
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PMID:Enhancement of X-ray toxicity in squamous cell carcinoma cell lines by DNA polymerase inhibitors. 791 17

Duck hepatitis B virus (DHBV) carrier ducks of one week old were injected with Ara-A (adenine arabinoside) of different dose including 2.5 (11 ducks), 5.0 (11), 10.0 (10) and 20.0 (10) mg/kg for 14 days. This antiviral effect showed dose-dependence up to 5.0 mg/kg and this dose seemed effective to obtain significant antiviral effect. Viral DNA and DNA polymerase activity were reduced significantly from the 1st week after starting the administration of Ara-A. This antiviral effect was maintained even at the 1st week after discontinuation of the drug. These findings were quite similar to those observed in HBV carriers. With the increasing necessity of Ara-A treatment in patients who will not respond to interferon therapy, DHBV seemed a suitable model for the investigation of the dose and antiviral effect of Ara-A treatment in humans.
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PMID:[The effects of Ara-A on viral markers in duck hepatitis B virus carrier ducks]. 841 47

Marine sponges are currently one of the richest sources of pharmacologically active compounds found in the marine environment. These bioactive molecules are often secondary metabolites, whose main function is to enable and/or modulate cellular communication and defense. They are usually produced by functional enzyme clusters in sponges and/or their associated symbiotic microorganisms. Natural product lead compounds from sponges have often been found to be promising pharmaceutical agents. Several of them have successfully been approved as antiviral agents for clinical use or have been advanced to the late stages of clinical trials. Most of these drugs are used for the treatment of human immunodeficiency virus (HIV) and herpes simplex virus (HSV). The most important antiviral lead of marine origin reported thus far is nucleoside Ara-A (vidarabine) isolated from sponge Tethya crypta. It inhibits viral DNA polymerase and DNA synthesis of herpes, vaccinica and varicella zoster viruses. However due to the discovery of new types of viruses and emergence of drug resistant strains, it is necessary to develop new antiviral lead compounds continuously. Several sponge derived antiviral lead compounds which are hoped to be developed as future drugs are discussed in this review. Supply problems are usually the major bottleneck to the development of these compounds as drugs during clinical trials. However advances in the field of metagenomics and high throughput microbial cultivation has raised the possibility that these techniques could lead to the cost-effective large scale production of such compounds. Perspectives on biotechnological methods with respect to marine drug development are also discussed.
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PMID:Antiviral lead compounds from marine sponges. 2111 10


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