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

---

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

The retroviral protease (PR) is responsible for cleaving precursor proteins that contain the virion structural proteins and enzymes. Highly potent inhibitors of the human immunodeficiency virus type-1 PR have been developed, and to date, five of these inhibitors have been approved for clinical use. These inhibitors bind to the active site of the dimeric PR and represent transition state analogs. Combination therapy in which a potent protease inhibitor is combined with inhibitors of the viral DNA polymerase reverse transcriptase can result in the apparent complete suppression of virus replication. Low virus loads associated with suppressed replication are resulting in dramatic reductions in the rate of disease progression. However, incomplete suppression of virus replication results in the selection of resistant variants. Resistance to protease inhibitors is the result of mutations within the PR coding domain, and most of these mutations are able to contribute to cross-resistance among this class of inhibitors.
...
PMID:Human immunodeficiency virus type-1 protease inhibitors: therapeutic successes and failures, suppression and resistance. 1079 12

We report a 63-year-old male with HIV encephalopathy, whose initial symptom was acutely progressing dementia. He tested positive for HIV antibody, and HIV-RNA count was 2.8 x 10(5) copy/ml. All opportunistic infections that could cause dementia were ruled out. Dementia remarkably improved after the combination antiretroviral therapy of three types of drugs, two being nucleoside analog reverse transcriptase inhibitors and one being a protease inhibitor. The combination therapy could be very effective for the treatment of HIV dementia.
...
PMID:[A case of HIV encephalopathy with dementia which showed significant improvement after the combination antiretroviral therapy]. 1083 42

We investigated HIV-1 reverse transcriptase (RT) polymorphisms of plasma isolates from 98 HIV-1-infected study subjects with >2 years of antiretroviral therapy who were failing their current protease inhibitor (PI)-containing regimen. In 1 patient, we detected a virus with a heavily mutated beta3-beta4 connecting loop of the HIV-1 RT fingers subdomain, consisting of a single aspartate codon insertion between positions 69 and 70 and five additional variations: 64N, K65, K66, 67G, 68Y, T69, Ins D, 70R, W71, R72, K73, 74I. Mutants with the recently described 2-aa insertions between codons 68 and 70 of RT were detected in another 3 patients. Among the four isolates with the 1- or 2-aa insertions, the novel genotype was the most refractory to therapy and displayed the highest level of phenotypic resistance to nucleoside reverse transcriptase inhibitors (NRTIs). Follow-up samples demonstrated that the novel mutant represents a stable genetic rearrangement and that the amino acid insertions can coexist with nonnucleoside analogue reverse transcriptase inhibitors (NNRTI) mutations resulting in phenotypic resistance to both NRTIs and NNRTIs. An increasing number of HIV-1 isolates containing various insertions in the beta3-beta4 hairpin of the HIV-1 RT fingers subdomain appear to emerge after prolonged therapy with different NRTIs, and these polymorphisms can confer multiple drug resistance against NRTIs.
...
PMID:A novel genotype encoding a single amino acid insertion and five other substitutions between residues 64 and 74 of the HIV-1 reverse transcriptase confers high-level cross-resistance to nucleoside reverse transcriptase inhibitors. Abacavir CNA2007 International Study Group. 1084 27

HIV-protease inhibitors demonstrated such high efficacy in short-term studies that they have been approved by the FDA, even though possible toxicity still needs further investigation. In the period between January 1997 and August 1998, 101 patients, staying at San Patrignano Medical Centre (Italy), received an HIV protease inhibitor (indinavir) plus two nucleoside reverse transcriptase inhibitors (NRTI's) selected from the following: AZT, didanosine, zalcitabine, lamivudine or stavudine. Seventy-three patients were male, 28 female and their ages ranged from 25 to 60 years, with an average of 34. At the end of the study, 84 patients were suitable for evaluation, as the other 17 dropped out for various reasons. Forty-eight patients (57.1%) developed cheilitis, 34 (40.5%) experienced diffuse cutaneous dryness and pruritus, 10 (11.9%) developed asteatotic dermatitis on the trunk, arms and thighs and another 10 (11.9%) complained of scalp defluvium. A severe alopecia was observed in only 1 patient (1.2%), while 6 reported that their body hair had become fairer, thinner and shed considerably. Multiple pyogenic granulomas were observed in the toenails of 5 patients (5. 9%). Softening of the nail plate was noted in 5 subjects as well. A peripheral lipodystrophy syndrome was noted in 12 patients (14.3%). Among these, one patient only developed a "buffalo hump" and another had diffused lipomatosis. The temporal relationship between the taking of indinavir and the onset of such cutaneous effects was striking. This was confirmed by the regression of symptoms in those patients who later discontinued indinavir. The emerging side effects of protease inhibitors require a multidisciplinary team for adequate diagnosis and treatment. Cutaneous toxicity involving the patient's own body image has a peculiar influence on compliance to the treatment and the patient's quality of life.
...
PMID:Cutaneous side effects induced by indinavir. 1084 57

The frequency of protease and reverse transcriptase (RT) gene mutations was determined in HIV-1 strains from 153 patients entering the CPCRA 046 (GART) study who were failing triple-drug regimens consisting of one protease inhibitor (PI) and two RT inhibitors. Population-based sequence analyses showed that nearly all patients had similar RT gene mutations regardless of prior drug exposure, although the M184V mutation was significantly less prevalent in patients not recently treated with lamivudine. Whilst typical inhibitor-specific ('signature') protease gene mutations were found in patients failing their first PI, these mutations were significantly less likely to be found in patients exposed to two or more PIs. Protease gene mutations associated with multi-PI resistance were more likely to be observed in patients treated with more than one PI. These results suggest sequential treatment with PIs select for a relatively limited number of protease gene mutations that likely originated during early PI therapy. These protease gene mutations and a similarly limited set of RT gene mutations appear to be responsible for treatment failure in antiretroviral therapy.
...
PMID:Frequency of antiretroviral drug resistance mutations in HIV-1 strains from patients failing triple drug regimens. The Terry Beirn Community Programs for Clinical Research on AIDS. 1084 94

(1) Combivir is a fixed-dose combination of two HIV reverse transcriptase inhibitors: zidovudine (300 mg) + lamivudine (150 mg). (2) A meta-analysis of four trials shows that this combination is more effective clinically than zidovudine monotherapy. One trial also shows that clinical efficacy is even better with the triple combination of the protease inhibitor indinavir with zidovudine + lamivudine. (3) The risk of anaemia and neutropaenia necessitates blood cell monitoring during treatment. (4) Compared with lamivudine and zidovudine taken separately, Combivir does not reduce the frequency of doses (two a day), but the daily number of tablets falls from four to two, provided that the patient does not require dose adjustment.
...
PMID:Zidovudine + lamivudine: new preparation. Fewer tablets required. 1084 57

(1) Recent consensus recommendations agree that first-line treatment of HIV infection should consist of a three-drug regimen combining a protease inhibitor and two nucleoside reverse transcriptase inhibitors. Some recommendations specifically advise against using the current formulation of saquinavir, but none express a preference for one of the other three protease inhibitors currently marketed in France (indinavir, nelfinavir and ritonavir). (2) These HIV protease inhibitors have established efficacy on viral load and the CD4+ lymphocyte count. Saquinavir may have lower virological efficacy. (3) The clinical efficacy of three-drug regimens containing indinavir or saquinavir is well demonstrated in patients at an advanced stage of HIV disease. (4) The risk of viral resistance is not currently a factor in choosing a HIV protease inhibitors. (5) Several epidemiological studies have compared the risk of adverse effects on three-drug regimens including indinavir, ritonavir or saquinavir. In these studies saquinavir was the best-tolerated drug and ritonavir the worst-tolerated. (6) Ritonavir interacts with many drugs. The poor bioavailability of the current saquinavir formulation also leads to risk of interactions. (7) Treatment constraints differ from one protease inhibitor to another, and these must be taken into account case by case. (8) The daily cost of treatment is not currently an important factor in choosing among the various preparations. (9) Taking into account efficacy, adverse effects, interactions and treatment constraints, the combination of indinavir with two nucleoside reverse transcriptase inhibitors currently seems to be the best choice for the largest number of patients. (10) If problems of compliance arise, nelfinavir can be an alternative to indinavir. (11) In patients at an advanced stage of HIV disease who comply well with their treatment, saquinavir can also be an alternative to indinavir.
...
PMID:The choice of HIV protease inhibitor: indinavir is currently the best option. 1084 67

Genotypes that confer drug resistance to reverse transcriptase inhibitors and protease inhibitors were evaluated in HIV-1 proviral DNA obtained from peripheral blood mononuclear cell samples. Fifty-three HIV-1-infected patients were studied, 19 of whom had not received antiretroviral treatment. In the other 34 patients, 9 had been treated with combinations of two reverse transcriptase inhibitors (AZT, ddI, d4T, 3TC) and 25 had been treated with triple antiretroviral therapy including a protease inhibitor (nelfinavir, indinavir, saquinavir, ritonavir). To determine the presence of mutations involved in the development of resistance to reverse transcriptase inhibitors a hybridization Microtiter assay was carried out. Mutations were detected in treated patients as well as in those without previous antiretroviral treatment, with the most frequent mutations being those that confer resistance to AZT, followed by those that develop cross-resistance to ddI/ddC and 3TC, which are the most commonly used drugs to date. No mutations were detected to any nucleoside analog in only 13 cases. To analyze the presence of mutations in the protease gene a dot-blot hybridization was carried out which included the mutations in codons 36, 82 and 90. Mutation 82 was detected in one case. Therefore, with the aim of determining the pattern of genotypic mutations in patients infected with HIV-1 and in order to make the best therapeutic choice, it would be recommended to consider carrying out genotypic resistance assays in clinical practice.
...
PMID:[Evaluation of mutations that confer resistance to nucleoside analogs and protease inhibitors in HIV-1-infected patients. Study Group on Resistance to Antiretroviral Agents]. 1085 10

We have analyzed the sequences of HIV-1 reverse transcriptase and protease genes in peripheral blood mononuclear cells obtained from patients receiving antiretroviral therapy to evaluate the drug resistance-associated mutations. Of 84 HIV-1-infected individuals treated with reverse transcriptase inhibitors, 43 (51.2%) have been found to carry amino acid substitutions predicted to acquire drug-resistances. One to 3 mutations at amino acid residues reported to be associated with protease inhibitor-resistance were detected in more than 80% of protease inhibitor-naive patients. However, these pre-existing mutations did not seem to raise a real resistance after the initiation of therapy with protease inhibitors. Phenotypic resistance assay was performed with 6 clinical isolates to compare with genotypic resistance. In most of the cases, phenotype was correlated with genotypic changes, however, two strains which were isolated from patients having no experience of chemotherapy showed a decrease in susceptibility to several drugs without any resistance-related mutations detected in their genes. Taken together, determination of phenotypic resistance is necessary, especially when a newly-infected patients starts antiviral therapy.
...
PMID:[Detection of genotypic and phenotypic drug-resistant HIV-1 in patients receiving antiretroviral therapy]. 1086 Mar 57

We have compared the results (on-treatment analyses) of 2 randomized clinical trials of protease inhibitor-sparing regimens in drug-naive patients. In the INCAS (Italy, Netherlands, Canada, Australia) study, the mean decrease in plasma viral load over 52 weeks was 2.2 log(10) copies/mL in 40 patients who were receiving zidovudine/didanosine/nevirapine (18 [45%] had maximal suppression), with a mean increase in CD4 T cell counts of 139 cells/microL. In protocol 0021 Part II, the mean decrease in plasma viral load over 52 weeks was 2.1 log(10) copies/mL in 34 patients who were receiving zidovudine/lamivudine/delavirdine (20 [59%] had maximal suppression), with a mean increase in CD4 T cell counts of 88 cells/microL. The virologic and immunologic efficacy of the 2 triple-drug regimens are similar. Until results of long-term studies are available to establish whether a preferred approach to initial therapy exists, nonnucleoside reverse transcriptase inhibitors may be a valuable alternative to protease inhibitors in the initial therapy of antiretroviral-naive, moderately immunosuppressed patients.
...
PMID:Initial therapy with protease inhibitor-sparing regimens: evaluation of nevirapine and delavirdine. 1086 Aug 97


<< Previous 1 2 3 4 5 6 7 8 9 10

---