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)

Fat redistribution in the setting of protease inhibitor use is increasingly common and is associated with insulin resistance in human immunodeficiency virus (HIV)-infected patients. However, little is known regarding the factors that may contribute to abnormal insulin regulation in this population. We assessed fasting insulin levels in HIV-infected men and determined the relationship among insulin, body composition, endogenous gonadal steroid concentrations, and antiviral therapy in this population. We also determined the effects of exogenous testosterone administration using the homeostatic model for insulin resistance (HOMA IR) in hypogonadal HIV-infected men with the acquired immunodeficiency syndrome wasting syndrome. Fifty HIV-infected men with acquired immunodeficiency syndrome wasting were compared with 20 age- and body mass index (BMI)-matched healthy control subjects. Insulin concentrations were significantly increased in HIV-infected patients compared to those in control patients (16.6+/-1.8 vs. 10.4+/-0.8 microU/mL; P<0.05) and were increased in nucleoside reverse transcriptase (NRTI)-treated patients who did not receive a protease inhibitor (PI; 21.7+/-4.3 vs. 10.4+/-0.8 microU/mL; P<0.05). Insulin concentrations and HOMA IR were inversely correlated with the serum free testosterone concentration (r = -0.36; P = 0.01 for insulin level; r = -0.30; P = 0.03 for HOMA), but not to body composition parameters, age, or BMI. In a multivariate regression analysis, free testosterone (P = 0.05), BMI (P<0.01), and lean body mass (P = 0.04) were significant. Lower lean body mass and higher BMI predicted increased insulin resistance. The HIV-infected patients demonstrated an increased trunk fat to total fat ratio (0.49+/-0.02 vs. 0.45+/-0.02; P<0.05) and an increased trunk fat to extremity fat ratio (1.27+/-0.09 vs. 0.95+/-0.06, P = 0.01), but a reduced extremity fat to total fat ratio (0.44+/-0.01 vs. 0.49 + 0.01; P = 0.02) and reduced overall total body fat (13.8+/-0.7 vs. 17.2+/-0.9 kg; P<0.01) compared to the control subjects. Increased truncal fat and reduced extremity fat were seen among NRTI-treated patients, but this pattern was most severe among patients receiving combined NRTI and PI therapy [trunk fat to extremity ratio, 1.47+/-0.15 vs. 0.95+/-0.06 (P<0.01); extremity fat to total fat ratio, 0.40+/-0.02 vs. 0.49+/-0.01 (P<0.05)]. Insulin responses to testosterone administration were investigated among 52 HIV-infected men with hypogonadism and wasting (weight <90% ideal body weight and/or weight loss >10%) randomized to either testosterone (300 mg, im, every 3 weeks) or placebo for 6 months. Testosterone administration reduced HOMA IR in the HIV-infected men (-0.6+/-0.7 vs. +1.41+/-0.8, testosterone vs. placebo, P = 0.05) in association with increased lean body mass (P = 0.02). These data demonstrate significant hyperinsulinemia in HIV-infected patients, which can occur in the absence of PI use. In NRTI-treated patients not receiving PI, a precursor phenotype is apparent, with increased truncal fat, reduced extremity fat, and increased insulin concentrations. This phenotype is exaggerated in patients receiving PI therapy, with further increased truncal fat and reduced extremity fat, although hyperinsulinemia per se is not worse. Endogenous gonadal steroid levels are inversely related to hyperinsulinemia in HIV-infected men, but reduced lean body mass and increased weight are the primary independent predictors of hyperinsulinemia. Indexes of insulin sensitivity improve in response to physiological androgen administration among hypogonadal HIV-infected patients, and this change is again related primarily to increased lean body mass in response to testosterone administration.
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PMID:Fasting hyperinsulinemia in human immunodeficiency virus-infected men: relationship to body composition, gonadal function, and protease inhibitor use. 1063 60

Indinavir is a protease inhibitor used in the treatment of patients with HIV infection. Combination antiretroviral therapy with indinavir plus 2 nucleoside reverse transcriptase inhibitors (NRTIs) is associated with greater reductions in viral load, greater increases in CD4+ cell counts, and reduced morbidity and mortality when compared with 2 NRTIs alone. In the landmark clinical trial ACTG 320, the rate of progression to AIDS or death (primary end-point) among zidovudine-experienced patients treated with indinavir, zidovudine and lamivudine was approximately half that of patients who received only zidovudine plus lamivudine (6 vs 11%; p < 0.001). The durability of an indinavir-containing regimen was demonstrated in Merck protocol 035, an ongoing trial in which a significant proportion of patients had sustained viral suppression for up to 3 years. Merck protocol 039, also an ongoing trial, showed a greater effect on surrogate markers of HIV disease progression with indinavir-based triple therapy than with zidovudine plus lamivudine or indinavir monotherapy in patients with advanced disease (median baseline CD4+ count 15 cells/microL). Numerous additional clinical trials have established the beneficial antiviral and immunological effects of indinavir in both antiretroviral-naive and -experienced patients with HIV infection. Indinavir is associated with various drug class-related adverse events, including gastrointestinal disturbances (e.g. nausea, diarrhoea), headache and asthenia/fatigue. A lipodystrophy syndrome has been commonly reported with indinavir and other protease inhibitors combined with NRTIs, but it has also been reported in many protease inhibitor-naive patients, and a definitive causal link has not been established between the syndrome and protease inhibitors. Nephrolithiasis may develop in about 9% of patients receiving indinavir but does not appear to be associated with other protease inhibitors; <0.5% of patients receiving indinavir discontinue the drug because of nephrolithiasis, which may be the extreme end of a continuum of crystal-related renal syndromes. Additional renal problems (e.g. nephropathy) have been reported in small numbers of patients receiving indinavir. In summary, indinavir is a protease inhibitor with well documented efficacy when used as part of combined therapy in patients with HIV infection. Both US and UK treatment guidelines continue to recommend protease inhibitor-based regimens including indinavir as a first-line option. Indinavir is being studied as a twice daily and once daily regimen with a low dosage of ritonavir as a way to alleviate tolerability, drug interaction and patient compliance/adherence issues. Indinavir-containing triple therapy has demonstrated positive effects not only on surrogate markers of disease progression, but also on clinical end-points of mortality and morbidity in patients with HIV disease. Protease inhibitors are a significant advance in the care of patients with HIV infection, and, in an era of evidence-based medicine, indinavir represents an important component of antiretroviral treatment strategies.
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PMID:Indinavir: a review of its use in the management of HIV infection. 1065 94

Twenty-four adults infected with human immunodeficiency virus type 1 (HIV-1) with central nervous system symptoms were studied for antiretroviral resistance mutations in HIV-1 RNA obtained from paired cerebrospinal fluid (CSF) and plasma samples. Paired sequences were obtained from 21 and 13 patients for reverse transcriptase (RT) and for protease, respectively. Mutations conferring resistance to the RT inhibitors zidovudine, lamivudine, or nevirapine were detected in 14 patients, including 11 pretreated and 3 drug-naive subjects. The mutation patterns in the 2 compartments were different in most patients. Genotypic resistance to protease inhibitors was detected in both plasma and CSF from 1 patient treated with multiple protease inhibitors. However, accessory protease inhibitor resistance mutations at polymorphic sites were different in plasma and CSF in several patients. Partially independent evolution of viral quasispecies occurs in plasma and CSF, raising the possibility that compartmentalization of drug resistance may affect response to antiretroviral treatment.
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PMID:Antiretroviral resistance mutations in human immunodeficiency virus type 1 reverse transcriptase and protease from paired cerebrospinal fluid and plasma samples. 1066 67

Nevirapine is the first non nucleoside reverse transcriptase inhibitor registered in Belgium and indicated in the treatment of HIV-1 infection. In association with 2 nucleoside analogues, its efficiency is similar to a tritherapy with protease inhibitor, particularly in naive patients with low viral load. It has a good tolerance profile and is easy to take. Studies in progress should permit to widen its indications.
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PMID:[Pharma-clinics. The drug of the month. Nevirapine. Viramune]. 1068 2

The CD8(+)-T-cell response to human immunodeficiency virus type 1 (HIV-1) is considered to be important in host control of infection and prevention of AIDS. We have developed a single-cell enzyme immunoassay (enzyme-linked immunospot assay) specific for gamma interferon (IFN-gamma) production stimulated by either autologous B-lymphoblastoid cell lines (B-LCL) infected with vaccinia virus vectors expressing HIV-1 proteins or synthetic peptides representing known HIV-1 CD8(+) cytotoxic T-lymphocyte (CTL) epitopes. Single-cell IFN-gamma production stimulated by HIV-1 Gag-, Pol-, and Env-expressing B-LCL was a reliable measure of HIV-1-specific T-cell immunity in peripheral blood CD8(+) T cells from HIV-1 infected individuals. This method was more sensitive than stimulation of IFN-gamma by direct infection of the cultures with HIV-1-vaccinia virus vectors. Comparable results were found for IFN-gamma production in CD8(+) T cells from HIV-1-negative, cytomegalovirus (CMV)-seropositive, healthy donors stimulated with B-LCL expressing the CMV pp65 lower matrix protein. HIV-1 peptides were immunodominant for both CD8(+) single-cell IFN-gamma production and CTL precursor frequencies. The number of cells producing IFN-gamma decreased in individuals with late-stage HIV-1 infection and was temporally enhanced during combination antiretroviral therapy with two reverse transcriptase nucleoside inhibitors and a protease inhibitor.
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PMID:CD8(+) T-cell gamma interferon production specific for human immunodeficiency virus type 1 (HIV-1) in HIV-1-infected subjects. 1070 5

Nelfinavir is a novel protease inhibitor that exhibits good inhibitory activity against human immunodeficiency virus type 1 (HIV-1) and is currently used in combination with reverse transcriptase inhibitors for the management of HIV infection. In this study we analysed the pharmacokinetic profile of nelfinavir after multiple oral doses in 18 HIV-infected patients during a combination regimen of nelfinavir plus efavirenz and stavudine. Patients who received the study drug for >/=4 weeks were considered for pharmacokinetic evaluation. Blood samples were obtained at the following times: 0 (before nelfinavir administration), 1, 2, 3, 4, 6 and 8 h after administration. Nelfinavir plasma concentrations were analysed by a specific and validated HPLC assay with ultraviolet detection. Nelfinavir concentration-time data were analysed by compartmental and non-compartmental techniques and the pharmacokinetic parameters of nelfinavir were determined according to a one-compartment model. We found a high variability between individuals in nelfinavir plasma concentrations. The mean average drug plasma concentration was 2.22 +/- 1.25 mg/L and the mean AUC during the dosing interval was 17.7 +/- 10.0 mg*h/L. The mean nelfinavir trough plasma concentration was 1.58 +/- 1.0 mg/L. A good relationship was found between AUC(0-8h) and the plasma concentrations measured at 6 h, and the trough plasma concentrations made total body exposure for nelfinavir less predictable. Alternatively, a 2 h abbreviated AUC provides a good estimate of the full AUC(0-8h). Comparing the pharmacokinetic parameters obtained in our patients with those reported for patients receiving nelfinavir monotherapy or nelfinavir combined with nucleoside analogues, one observes substantial overlap with nelfinavir concentrations achieved without efavirenz.
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PMID:Clinical pharmacokinetics of nelfinavir combined with efavirenz and stavudine during rescue treatment of heavily pretreated HIV-infected patients. 1070 54

Secretory leucocyte protease inhibitor (SLPI) is a potent inhibitor of granulocyte elastase and cathepsin G, and also an inhibitor of pancreatic enzymes like trypsin, chymotrypsin and pancreatic elastase. SLPI has also been shown to inhibit HIV-1 infections by blocking viral DNA synthesis. Since SLPI is an inhibitor of pancreatic proteases we wished to investigate whether SLPI was also actually produced in the pancreas. M-RNA from human pancreatic tissue showed evidence of SLPI production using the reverse transcriptase polymer chain reaction technique (RT-PCR). Using immunohistochemical methods SLPI was demonstrated in the beta-cells of the islets of Langerhans. The function could be local protease/antiprotease regulation or antiviral/antibacterial defence in the close vicinity of the cell surface, or even inside the beta-cell itself.
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PMID:Production of secretory leucocyte protease inhibitor (SLPI) in human pancreatic beta-cells. 1070 52

We constructed human immunodeficiency virus (HIV) mutants by replacing the matrix domain with sequences encoding the viral protease or p6* and protease. The chimeras retaining matrix myristylation and processing signals underwent efficient autoprocessing with severely defective particle budding. The budding defects of the chimeras were rescued by suppressing the chimera protease activity either through addition of an HIV protease inhibitor or through inactivating the chimera protease via a substitution mutation of the catalytic aspartic acid residue. This resulted in the release of chimeric virus-like particles with the density of a wild-type retrovirus particle. In addition, the assembly-competent but processing-defective chimeras produced proteolytically processed particles with significant reverse transcriptase activity when a downstream native pol gene was present. These results suggest that HIV has the potential to adapt heterologous sequences in place of the matrix sequence without major effects on virus-like particle budding. In addition, the positions of the protease and substrate accessibility may contribute significantly toward avoiding a premature Gag or Gag-Pol process, which leads to severe defects in both particle budding and incorporation.
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PMID:Assembly and processing of human immunodeficiency virus Gag mutants containing a partial replacement of the matrix domain by the viral protease domain. 1070 61

Phenotypic drug susceptibility assays of human immunodeficiency virus type 1 (HIV-1) isolates generally use time-consuming, expensive assays with peripheral blood mononuclear cells. A new HIV-1 indicator cell line, MAGI-CCR5, has been developed and applied for this purpose. This cell line expresses human CD4, the two major HIV-1 coreceptors, CCR5 and CXCR4, the reporter gene beta-galactosidase driven by the HIV-1 LTR, and quantitates infection within 48 h. A panel of reference strains and primary HIV-1 isolates were all found to infect this cell line. Susceptibility assays with a nucleoside (zidovudine, ZDV) and a non-nucleoside reverse transcriptase inhibitor (nevirapine, NVP) were performed with reference and primary isolates. The assay was modified into two steps for protease inhibitor (indivinavir, IDV and ritonavir, RTV) susceptibility assays. Primary isolates derived from drug naive patients displayed mean baseline 50% effective concentrations (EC50) of 0.14 microM for ZDV, 0.33 microM for NVP, and 0.02 microM for IDV. Isolates derived from patients under treatment displayed increased EC50 concentrations. The MAGI-CCR5 cell line offers a rapid, efficient, and reproducible method of testing a wide range of HIV-1 isolates for drug susceptibility.
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PMID:Rapid phenotypic drug susceptibility assay for HIV-1 with a CCR5 expressing indicator cell line. 1071 48

The prevalence of phenotypic drug resistance was assessed in 60 patients with a viral rebound after they received a protease inhibitor (PI)- or nonnucleoside reverse transcriptase inhibitor (NNRTI)-containing regimen (baseline). Resistance testing was done within 36 weeks of viral rebound; no resistance testing was available at baseline. All patients had previously received zidovudine; 86.0% had received lamivudine. In total, 45.1% of the patients had strains resistant to the PI that they started and 88.9% given nevirapine had strains with reduced susceptibility to that drug. Overall, 46 patients (76.7%) harbored a strain resistant to >/=1 drug of their initial PI- or NNRTI-containing regimen. Of 53 patients who remained on treatment at the time of the study (40 had switched to a different combination from that at baseline), 6 harbored isolates susceptible to all drugs they had ever received. Thus, patients with viral rebound while on potent antiretroviral therapy usually have reduced susceptibility to >/=1 drug. Viral rebound also occurs in persons in whom resistant strains could not be detected by the assay used.
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PMID:Resistance profiles in patients with viral rebound on potent antiretroviral therapy. 1072 May 43


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