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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Combinations of 3'-azido-3'-deoxythymidine and phosphonoformate produced a moderate synergistic inhibitory effect against human immunodeficiency virus type 1 in vitro at concentrations that are easily achieved in humans. The synergistic effect was more pronounced with increasing concentrations and was not secondary to toxic effects of the drugs. 3'-Azido-3'-deoxythymidine neither inhibited the replication of human cytomegalovirus in human embryonic lung fibroblasts nor interfered with the anticytomegalovirus effect of phosphonoformate. By using partially purified reverse transcriptase of human immunodeficiency virus type 1 and human cytomegalovirus DNA polymerase, various combinations of 3'-azido-3'-deoxythymidine-5'-triphosphate and phosphonoformate produced strong indications of additive interactions. The synergistic interactions in infected cells and the additive effects observed at the reverse transcriptase level indicate that mechanisms other than the reverse transcriptase may be of importance for the inhibition of human immunodeficiency virus replication by these two compounds. A concomitant treatment of cytomegalovirus infections, such as cytomegalovirus retinitis, with phosphonoformate in patients with acquired immunodeficiency syndrome receiving 3'-azido-3'-deoxythymidine may be appropriate, and this combination may also be useful in controlling human immunodeficiency virus infection.
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PMID:Combinations of 3'-azido-3'-deoxythymidine (zidovudine) and phosphonoformate (foscarnet) against human immunodeficiency virus type 1 and cytomegalovirus replication in vitro. 254 87

3'-Azido-3'-deoxythymidine (AZT) inhibits the replication of the human immunodeficiency virus (HIV) by blocking the formation of the phosphodiester bond and has been used clinically for the treatment of HIV infection. To assess the effect of AZT on the replication of hepadnaviruses, which replicate through reverse transcription, both the liver tissue and primary cultured hepatocytes from ducklings previously infected with duck hepatitis B virus (DHBV) were examined for DHBV DNA before and after the treatment with AZT. We did not observe suppression of DHBV replication at any doses in our system as measured by viral DNA synthesis in infected duck hepatocytes. The data strongly suggest that AZT has no inhibitory effect on DHBV reverse transcriptase.
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PMID:Effect of 3'-azido-3'-deoxythymidine on replication of duck hepatitis B virus in vivo and in vitro. 255 51

Zidovudine (Retrovir) is the only drug found to be useful for managing human immunodeficiency virus (HIV) infection in patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex. The drug is virostatic, ie, it prevents replication of HIV by inhibiting the enzyme reverse transcriptase. Zidovudine is well tolerated and provides short-term benefits by improving the quality of life and extending survival time. It is expensive and can be toxic, however, so its use requires close supervision. Zidovudine at present is approved only for patients with documented Pneumocystis carinii pneumonia or with a CD4 count below 200/mm3. Other probable indications include HIV wasting syndrome, HIV dementia complex, oral candidiasis, Kaposi's sarcoma, the presence of early markers of HIV infection, and HIV-related symptomatic thrombocytopenia. A stepwise approach to initiating zidovudine therapy should include detailed counseling and close surveillance.
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PMID:Zidovudine for treating AIDS. What physicians need to know. 266 55

A rapid expansion of our knowledge of drugs that intervene with human immunodeficiency virus (HIV) infection has taken place. This review covers known and potential anti-HIV targets, including receptor blocking agents, membrane stabilisers, reverse transcriptase inhibitors and chain terminators, RNases, agents altering activation, assembly, budding or regulation of transcription and translation, post-transcriptional modifications and other areas. Important or promising agents, such as zidovudine (ZVD; azidothymidine, AZT), dideoxycytidine, dideoxyinosine, foscarnet, interferons, imuthiol, isoprinosine and others that are either on the market or in advanced clinical trials are emphasised. Four years after the discovery of the aetiological agent, the first drug, zidovudine, has been registered. Many questions about this drug remain, however, owing to the haste with which it was developed. An unprecedented number of other compounds are under evaluation, making it difficult to assess the relative merits of the different compounds and thus set priorities for their development. The point has been reached where a better economical and intellectual framework is necessary so that researchers and physicians are not overwhelmed by the difficulties of conducting clinical trials during the epidemic and have a reasonable chance of keeping up with laboratory developments.
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PMID:Antiviral therapy in human immunodeficiency virus infection. 268 Apr 36

1. The development of effective drugs targeted at the underlying causative agent of AIDS (eg, HIV) is paramount to reducing morbidity and mortality. 2. Antiretroviral drugs may either inhibit HIV replication at the reverse transcriptase phase of the replication cycle or they may attack the cycle before HIV enters the healthy target cell. 3. AZT has been found to reduce the mortality of patients with AIDS and AIDS-related complex, decrease the frequency and severity of opportunistic infections, and may improve neurologic functioning.
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PMID:Future hope? Antiretroviral therapy to treat HIV. 268 56

3'-azido-3'-deoxythymidine is a thymidine analogue with an in vitro as well as in vivo efficacy towards HIV-mediated infection. Zidovudine exerts its action, following an intracellular three-step phosphorylation, through viral reverse transcriptase inhibition. Its half-life is approximately one hour. Oral biodisponibility is 65%, and passage through blood-brain barrier results in therapeutic levels is CSF. Clinical evaluation has enabled demonstration of a beneficial effect on survival of stage IV AIDS patients, when treated after a PCP episode. In this setting, aggregate survival ratios reach 73% after one year of follow-up, and 41% after 2 years. In addition, zidovudine activity has been demonstrated in treatment of HIV-induced thrombopenias as well as HIV-related central nervous system disorders. Presently, zidovudine therapeutic evaluation proceeds through the following main axes: dosage tuning (either by lowering of standard dose, and/or dose interval modification); combination with other antiviral therapies; lastly, patient treatment et an early stage of disease.
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PMID:[Zidovudine. The current status of its evaluation]. 269 36

A combination of antiviral therapies that target different sites in the human immunodeficiency virus type 1 (HIV-1) replicative cycle may be necessary for optimal treatment of HIV-1 infections. We evaluated the interactions of a soluble virus receptor (recombinant soluble CD4 or rsT4) and a reverse transcriptase inhibitor (azidothymidine, AZT) against HIV-1 replication in vitro. A variety of cell types was studied including peripheral blood mononuclear cells, a CD4-positive T-cell line, and a CD4-positive human monocyte cell line. The combination of rsT4 and AZT inhibited HIV-1 synergistically over a broad range of drug concentrations and multiplicities of infection in several different HIV-1 replication assays. Drug interactions were evaluated by the median-effect principle and the isobologram technique using a computer analysis. In all of the cell types tested, combinations of rsT4 and AZT were synergistic in vitro, without additive cytotoxicity.
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PMID:Synergistic inhibition of human immunodeficiency virus type 1 (HIV-1) replication in vitro by recombinant soluble CD4 and 3'-azido-3'-deoxythymidine. 278 46

Azidothymidine is a new antiviral drug that acts by competitive inhibition of reverse transcriptase of retroviruses. Azidothymidine is now widely used in treatment of patients with AIDS or ARC; the most important side effects of this drug are anaemia and neutropenia. Recently pigmentary changes of the nails (diffuse pigmentation and longitudinal or transverse bands) provoked by azidothymidine-treatment have also been reported. We describe a such case.
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PMID:[Nail pigmentation caused by azidothymidine]. 280 86

Viral infections, predominantly those of the herpes virus family, account for up to 16% of all clinically significant infections in AIDS patients. Acyclovir has provided successful treatment in AIDS patients suffering from severe herpes simplex and herpes zoster virus infections. Preliminary results are presented on newly developed acyclovir analogues. Desciclovir, an oral prodrug of acyclovir which is metabolized to acyclovir in vivo, allows treatment of virus infections per os, where high serum levels are needed, e.g. in Epstein-Barr virus infections. BW B759U, another analogue of acyclovir, has been used for the treatment of life-threatening or sight-threatening cytomegalovirus infections in AIDS patients. More than 80% of the patients treated for retinitis experienced stabilization or clinical improvement. Antiviral efficacy was demonstrated in 73% of the patients. Azidothymidine, a nucleoside analogue of thymidine, has been developed specifically to treat the HIV infection. Its antiviral activity is based on inhibition of reverse transcriptase. Phase I studies have demonstrated that azidothymidine is well tolerated. Its ability to cross the blood brain barrier makes it an attractive candidate for treatment of HIV. Trials to determine efficacy are in progress.
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PMID:Management of viral infections in AIDS patients. 303 16

Zidovudine is a potent in vitro inhibitor of human immunodeficiency virus (HIV) with varying efficacy against other retroviruses. With the exception of Epstein-Barr virus, all non-retroviruses tested so far have been insensitive to inhibition by zidovudine. In vivo, efficacy of zidovudine was demonstrated against Rauscher murine leukemia virus and feline leukemia virus. In both experimental models, infections completely resolved in animals when the drug was administered soon after infection. These results suggest that prompt initiation of zidovudine therapy, following a known exposure to HIV, should be considered. Mechanism studies show that zidovudine is phosphorylated to the monophosphate and diphosphate derivatives by the host cell cytosolic thymidine kinase and thymidylate kinase, respectively. The identity of the enzyme that phosphorylates zidovudine diphosphate is not known, but is believed to be the cellular nucleoside diphosphate kinase. The triphosphate of zidovudine appears to be the active form of the drug. Zidovudine triphosphate competes well with thymidine 5'-triphosphate for binding to the HIV reverse transcriptase and also functions as an alternative substrate. Incorporation of zidovudine monophosphate results in chain termination. However, it is not clear which mechanism, chain termination or competition with thymidine 5'-triphosphate, or a combination of both, is responsible for the inhibition of HIV replication.
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PMID:Spectrum of antiviral activity and mechanism of action of zidovudine. An overview. 304 82


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