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)

In many ways, chronic myeloid leukaemia (CML) serves as a paradigm for the utility of molecular methods in the diagnosis of malignancy or for monitoring the response of the patient to therapy. The Philadelphia (Ph) translocation provides an elegant example of how cytogenetic findings provided the starting point for understanding the genetic mechanisms involved in leukaemogenesis. The degree of reduction in tumour load after therapy is an important prognostic factor for CML patients. Several approaches have been introduced that can specifically detect the Ph translocation or its products; these approaches include fluorescent in situ hybridization, Southern blotting, western blotting and reverse transcriptase polymerase chain reaction (RT-PCR). Because non-quantitative RT-PCR analysis after therapy gives only limited information, quantitative or semiquantitative RT-PCR assays have been developed that enable the kinetics of residual BCR-ABL transcripts to be monitored over time in patients after allogeneic stem cell transplantation, interferon-alpha, or STI571 therapy.
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PMID:Minimal residual disease in chronic myeloid leukaemia patients. 1198 22

Hepatitis B virus (HBV) infection is a major global health concern and is the most common cause of chronic liver disease worldwide. The natural history and clinical outcomes of chronic HBV infection are determined by the viral replication cycle and the host immune responses. Treatment of chronic hepatitis B is directed at interrupting the natural history by suppressing HBV replication before development of any significant irreversible liver cell damage. Effective antiviral therapies should be followed by sustained suppression of HBV-DNA, normalization of transaminases levels and a stable stage of HBeAg seroconversion with persistence of circulating anti-HBeAg antibodies. Two major classes of antiviral therapeutic agents that have been approved for treatment of chronic hepatitis B are immunomodulating agents (i.e. interferon) and the nucleoside analogs (i.e. lamivudine). A 4-6 month course of interferon-alpha has resulted in improvement of survival in 20%-30% of patients with chronic hepatitis B who had elevated serum ALT levels without hepatic decompensation. Interferon-alpha therapy is associated with HBeAg seroconversion; normalization of ALT levels, reduced hepatic inflammation, and possibly reduced disease progression to cirrhosis and hepatocellular carcinoma. Interferon can also be used with caution in patients with early compensated cirrhosis. A 12-month course of lamivudine has been shown to be well tolerated and effective. Lamivudine can be used in decompensated cirrhosis and immunosuppressed patients and for prevention of recurrent HBV infection after liver transplantation. The response rates after 3 years of lamivudine therapy account for 40-65%. A major problem of antiviral treatment is the emergence of drug resistance conferred by mutations in the YMDD motif of HBV reverse transcriptase. The prevalence of YMDD mutations increases with longer durations of antiviral therapies and this has been detected in 20% of immunocompetent patients receiving lamivudine per year. Contentious issues remain when to stop the treatment if HBeAg seroconversion does not occur. Many new immunomodulatory therapies and antiviral agents are in various stages of clinical development and have shown some promise. Among newer HBV antivirals, adefovir dipivoxil, entecavir, emtricitabine, DAPD and clevudine appear to be at least as potent as lamivudine in suppressing HBV replication. In vitro studies have shown that YMDD mutations confer cross-resistance between lamivudine and emtricitabine. However, adefovir, dipivoxil, lobucavir, DAPD and possibly clevudine suppress replications of both YMDD mutants and wild types of HBV. Immunomodulatory approaches for treatment of chronic hepatitis B are conceptually attractive, but newer agents used to date (thymosin-alpha, interleukin-12, therapeutic vaccines) have not demonstrated sufficient efficacy for widespread use. Combinations of an immunomodulatory agent and nucleoside analog may improve the therapeutic efficacy and reduce the emergence of drug resistance. Nevertheless, combinations of interferon and lamivudine therapies do not confer such additional benefits. The next challenge for HBV treatment is to use antivirals in combination and/or in cyclical therapy to minimize the emergence of drug resistance and increase efficacy, particularly to achieve sustainable post-treatment suppression of HBV. Randomized prospective control trials of combined antiviral therapies given simultaneously or sequentially are needed to establish safe and effective combined regimens that can be recommended for future treatment strategies.
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PMID:Management of viral hepatitis B. 1200 May 99

After treatment of chronic hepatitis C virus (HCV), infection with interferon-alpha+/-ribavirin in a considerable proportion of patients with a virologic end-of-treatment response (ETR), a relapse during follow-up is observed. The biological background of relapse is unknown. Either antiviral therapy leads to a complete replication arrest and latent virions survive until the end-of-treatment or replication is not completely suppressed. For the latter hypothesis, residual HCV RNA should be detectable dependent on the sensitivity of the HCV RNA assay. In patients from different studies, serum or plasma samples from the end-of-treatment were investigated for the presence of HCV RNA with a standard polymerase chain reaction (PCR)-based assay and retested for comparison with a new highly sensitive transcription-mediated amplification (TMA)-based assay. Generally, in patients with virologic non-response or sustained virologic response (SR), no differences were observed between PCR- and TMA-based assays. In patients with relapse after standard interferon-alpha therapy with or without ribavirin, HCV RNA was detected in 33-36% of end-of-treatment samples previously negative by PCR-based assays. The lower rate of HCV RNA detected by TMA (7%) in end-of-treatment samples from patients after treatment with pegylated interferon-alpha 2a is most likely explained by the longer half-life of pegylated interferon-alpha in comparison with standard interferon-alpha. HCV RNA is detectable at the end-of-treatment by TMA in 7-36% of patients who were HCV RNA negative by reverse transcriptase (RT)-PCR-based methods. These PCR-negative/TMA-positive patients have to be considered as non-responders (NR) with a very low HCV RNA viral load. Future studies will show whether these patients benefit from prolonged antiviral therapy.
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PMID:Highly sensitive hepatitis C virus RNA detection methods: molecular backgrounds and clinical significance. 1246 74

Following 2 weeks acclimation to the running wheel in the home cages, an i.p. injection of a synthetic double-stranded RNA, polyriboinosinic:polyribocytidylic acid (poly I:C, 3 mg/kg), was performed to produce the immunologically induced fatigue in rats. The daily amounts of spontaneous running wheel activity decreased to about 40-60% of the preinjection level until day 9 with normal circadian rhythm, then gradually returned to the baseline level by day 14. Rats given a heat exposure (36 degrees C for 1 h) for the consecutive 3 days showed an increase in activity except for the first day. In the open field test, the total moving distance and the number of rearing of the poly I:C-injected rats decreased on day 1, but they were not different from the saline-injected group on day 7, suggesting that the poly I:C-induced fatigue on day 7 was not due to the peripheral problems such as muscle/joint pain, but involved the CNS. Quantitative analysis of mRNA levels using a real-time capillary reverse transcriptase-polymerase chain reaction (RT-PCR) method revealed that interferon-alpha (IFN-alpha) mRNA contents in the cortex, hippocampus, hypothalamic medial preoptic, paraventricular, and ventromedial nuclei were higher in the poly I:C group than those in the saline and heat-exposed groups on day 7, although the amount of interleukin-1 beta mRNA showed no differences. Serum adrenocorticotropic hormone and catecholamine levels were not significantly different between groups. The present results indicate that the prolonged fatigue induced by poly I:C, which is evaluated by the spontaneous running wheel activity, can be used as an animal model for the immunologically induced fatigue associated with viral infection, and suggest that brain IFN-alpha may play a role in this model.
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PMID:Prolonged effects of polyriboinosinic:polyribocytidylic acid on spontaneous running wheel activity and brain interferon-alpha mRNA in rats: a model for immunologically induced fatigue. 1289 23

After occupational exposure to HBV, HCV, and HIV, the patient from whom the potentially infectious material originates (index patient) as well as the exposed person should undergo serological and, if needed, molecular screening. Active and passive immunoprophylaxis after exposure to HBV is an effective tool against infection with hepatitis B virus in unvaccinated persons. The post-exposure prophylaxis (PEP) should be given within 24 h after exposure of an unprotected person to HBV-positive material. Once acute hepatitis B infection is diagnosed, therapy is not recommended for immunocompetent persons. At present, PEP against HCV infection is not available. Monotherapy with interferon-alpha avoids chronification in most patients suffering from acute hepatitis C. After exposure with an increased risk for transmission of HIV (percutaneous needle stick injury, cut), PEP should be recommended and can also be offered for further indications. PEP should be started as early as possible and carried out for 28 days. The recommended PEP consists of two inhibitors of the reverse transcriptase and one inhibitor of the protease.
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PMID:[Postexposure prophylaxis after occupational exposure to HBV, HCV and HIV]. 1499 Nov 39

After occupational exposure to HBV, HCV, and HIV, the patient from whom the potentially infectious material originates (index patient) as well as the exposed person should undergo serological and, if needed, molecular screening. Active and passive immunoprophylaxis after exposure to HBV is an effective tool against infection with hepatitis B virus in unvaccinated persons. The post-exposure prophylaxis (PEP) should be given within 24 h after exposure of an unprotected person to HBV-positive material. Once acute hepatitis B infection is diagnosed, therapy is not recommended for immunocompetent persons. At present, PEP against HCV infection is not available. Monotherapy with interferon-alpha avoids chronification in most patients suffering from acute hepatitis C. After exposure with an increased risk for transmission of HIV (percutaneous needle stick injury, cut), PEP should be recommended and can also be offered for further indications. PEP should be started as early as possible and carried out for 28 days. The recommended PEP consists of two inhibitors of the reverse transcriptase and one inhibitor of the protease.
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PMID:[Post-exposure prevention after occupational exposure to HBV, HCV and HIV]. 1503 65

After occupational exposure to HBV, HCV, and HIV, the patient from whom the potentially infectious material originates (index patient) as well as the exposed person should undergo serological and, if needed, molecular screening. Active and passive immunoprophylaxis after exposure to HBV is an effective tool against infection with hepatitis B virus in unvaccinated persons. The post-exposure prophylaxis (PEP) should be given within 24 h after exposure of an unprotected person to HBV-positive material. Once acute hepatitis B infection is diagnosed, therapy is not recommended for immunocompetent persons. At present, PEP against HCV infection is not available. Monotherapy with interferon-alpha avoids chronification in most patients suffering from acute hepatitis C. After exposure with an increased risk for transmission of HIV (percutaneous needle stick injury, cut), PEP should be recommended and can also be offered for further indications. PEP should be started as early as possible and carried out for 28 days. The recommended PEP consists of two inhibitors of the reverse transcriptase and one inhibitor of the protease.
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PMID:[Postexposure prevention after occupational exposure to HBV, HCV and HIV]. 1504 36

The current armamentarium for the chemotherapy of viral infections consists of 37 licensed antiviral drugs. For the treatment of human immunodeficiency virus (HIV) infections, 19 compounds have been formally approved: (i) the nucleoside reverse transcriptase inhibitors (NRTIs) zidovudine, didanosine, zalcitabine, stavudine, lamivudine, abacavir and emtricitabine; (ii) the nucleotide reverse transcriptase inhibitor (NtRTI) tenofovir disoproxil fumarate; (iii) the non-nucleoside reverse transcriptase inhibitors (NNRTIs) nevirapine, delavirdine and efavirenz; (iv) the protease inhibitors saquinavir, ritonavir, indinavir, nelfinavir, amprenavir, lopinavir (combined with ritonavir at a 4/1 ratio) and atazanavir; and the viral entry inhibitor enfuvirtide. For the treatment of chronic hepatitis B virus (HBV) infections, lamivudine as well as adefovir dipivoxil have been approved. Among the anti-herpesvirus agents, acyclovir, valaciclovir, penciclovir (when applied topically), famciclovir, idoxuridine and trifluridine (both applied topically) as well as brivudin are used in the treatment of herpes simplex virus (HSV) and/or varicella-zoster virus (VZV) infections; and ganciclovir, valganciclovir, foscarnet, cidofovir and fomivirsen (the latter upon intravitreal injection) have proven useful in the treatment of cytomegalovirus (CMV) infections in immunosuppressed patients (i.e. AIDS patients with CMV retinitis). Following amantadine and rimantadine, the neuraminidase inhibitors zanamivir and oseltamivir have recently become available for the therapy (and prophylaxis) of influenza virus infections. Ribavirin has been used (topically, as aerosol) in the treatment of respiratory syncytial virus (RSV) infections, and the combination of ribavirin with (pegylated) interferon-alpha has received increased acceptance for the treatment of hepatitis C virus (HCV) infections.
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PMID:Antiviral drugs in current clinical use. 1512 67

We reviewed 261 patients with chronicphase chronic myelogenous leukemia (CML) after interferon-alpha (IFN-alpha) failure treated with imatinib mesylate 400 mg daily. With a median follow-up time of 45 months, the major cytogenetic response rate was 73% and the complete cytogenetic response rate 63%. The estimated 4-year survival rate was 86%. Multivariate analysis for survival identified hematologic resistance to IFN-alpha (P =.01), splenomegaly (P =.03), and lack of any cytogenetic response after 3 months of therapy (P =.01) to have independent poor prognostic significance. Patients could be divided into good (no adverse factors), intermediate (1 adverse factor), and poor-risk groups (2 or 3 adverse factors; 12% of patients) with estimated 4-year survival rates of 96%, 86%, and 49%, respectively (P <.00001). The 4-year cumulative major molecular response (quantitative reverse transcriptase-polymerase chain reaction [Q-PCR] = BCR-ABL/ABL less than 0.05%) rate was 43% and complete molecular response rate (BCR-ABL undetectable) 26%. Compared with a historical group of 251 similar patients treated with nonimatinib therapies, imatinib mesylate was associated with a better 4-year survival rate (86% versus 43%; P <.0001); the survival advantage was confirmed by multivariate analysis (hazard ratio, 0.19; P <.0001).
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PMID:Long-term survival benefit and improved complete cytogenetic and molecular response rates with imatinib mesylate in Philadelphia chromosome-positive chronic-phase chronic myeloid leukemia after failure of interferon-alpha. 1519 56

Some cutaneous T-cell lymphomas, (CTCLs) clonal T cells are deficient in interferon signaling, making them promising targets for viral oncolysis. We evaluated cytopathic effects of measles virus (MV) in CTCL. CTCL cell lines and infiltrating lymphocytes in CTCL expressed MV receptors CD150 and CD46. In a phase 1 dose escalation trial a total of 16 injections of live MV, Edmonston-Zagreb vaccine strain, were given intratumorally to 5 patients with CTCL. Patients had antimeasles-serum antibodies and were pretreated with interferon-alpha to prevent uncontrolled virus spread. The well-tolerated treatment with MV resulted in clinical responses. Evaluation of biopsies, before and at 11 days after injection, by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated local viral activity with positive staining for MV nucleoprotein (NP), an increase of the interferon gamma (IFN-gamma)/CD4 and IFN-gamma/CD8 mRNA ratios and a reduced CD4/CD8 ratio. All patients demonstrated an increased antimeasles antibody titer after therapy. The data demonstrate that CTCLs are promising targets for an MV-based oncolytic therapy.
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PMID:Oncolytic measles virus in cutaneous T-cell lymphomas mounts antitumor immune responses in vivo and targets interferon-resistant tumor cells. 1596 18


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