Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Current treatments for human immunodeficiency virus (HIV) include both reverse transcriptase and protease inhibitors. Results from in vitro and clinical studies suggest that combination therapy can be more effective than single drugs in reducing viral burden. To evaluate compounds for combination therapy, stavudine (d4T), didanosine (ddI), or BMS-186,318, an HIV protease inhibitor, were combined with other clinically relevant compounds and tested in a T-cell line (CEM-SS) that was infected with HIV-RF or in peripheral blood mononuclear cells infected with a clinical HIV isolate. The combined drug effects were analyzed by the methods described by Chou and Talalay (Adv. Enzyme Regul. 22:27-55, 1984) as well as by Prichard et al. (Antimicrob. Agents Chemother. 37:540-545, 1993). The results showed that combining two nucleoside analogs (d4T-ddI, d4T-zidovudine [AZT], and d4T-zalcitabine [ddC]), two HIV protease inhibitors (BMS-186,318-saquinavir, BMS-186,318-SC-52151, and BMS-186,318-MK-639) or a reverse transcriptase and a protease inhibitor (BMS-186,318-d4T, BMS-186,318-ddI, BMS-186,318-AZT, d4T-saquinavir, d4T-MK-639, and ddI-MK-639) yielded additive to synergistic antiviral effects. In general, analysis of data by either method gave consistent results. In addition, combined antiviral treatments involving nucleoside analogs gave slightly different outcomes in the two cell types, presumably because of a difference in phosphorylation patterns. Importantly, no strong antagonism was observed with the drug combinations studied. These data should provide useful information for the design of clinical trials of combined chemotherapy.
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PMID:Evaluation of reverse transcriptase and protease inhibitors in two-drug combinations against human immunodeficiency virus replication. 872 99

Polyhexylcyanoacrylate nanoparticles loaded with either the human immunodeficiency virus (HIV) protease inhibitor saquinavir (Ro 31-8959) or the nucleoside analog zalcitabine (2',3'-dideoxycytidine) were prepared by emulsion polymerization and tested for antiviral activity in primary human monocytes/macrophages in vitro. Both nanoparticulate formulations led to a dose-dependent reduction of HIV type 1 antigen production. While nanoparticle-bound zalcitabine showed no superiority to an aqueous solution of the drug, a significantly higher efficacy was observed with saquinavir-loaded nanoparticles. In acutely infected cells, an aqueous solution of saquinavir showed little antiviral activity at concentrations below 10 nM, whereas the nanoparticulate formulation exhibited a good antiviral effect at a concentration of 1 nM and a still-significant antigen reduction at 0.1 nM (50% inhibitory concentrations = 4.23 nM for the free drug and 0.39 nM for the nanoparticle-bound drug). At a concentration of 100 nM, saquinavir was completely inactive in chronically HIV-infected macrophages, but when bound to nanoparticles it caused a 35% decrease in antigen production. Using nanoparticles as a drug carrier system could improve the delivery of antiviral agents to the mononuclear phagocyte system in vivo, overcoming pharmacokinetic problems and enhancing the activities of drugs for the treatment of HIV infection and AIDS.
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PMID:Efficiency of nanoparticles as a carrier system for antiviral agents in human immunodeficiency virus-infected human monocytes/macrophages in vitro. 872 20

The therapeutic utility of a human immunodeficiency virus type 1 (HIV-1) protease inhibitor may depend on its intracellular concentration, which is a property of its uptake, metabolism, and/or efflux. Previous studies in our laboratory indicated that the addition of alpha 1 acid glycoprotein (alpha 1 AGP) to the medium markedly increased the amount of the drug required to limit infection in vitro. In this study, physiologically relevant concentrations of alpha 1 AGP and a radiolabeled inhibitor, A-80987, were used to determine both the uptake and activity of the agent in HIV-1-infected human peripheral blood mononuclear cells and cell lines. Both the uptake and efflux of 14C-labeled A-80987 were rapid (t1/2, < 5 min). Uptake of the drug was linearly dependent on the concentration but insensitive to the metabolic inhibitors KF, sodium cyanide, or CCCP (carbonyl cyanide m-chlorophenyl hydrazone). The amount of A-80987 which entered the cells was inversely proportional to the concentration of alpha 1 AGP (r2, 0.99) and directly proportional to the amount of extracellular non-protein-bound drug (r2, 0.99). Most importantly, the antiviral activity of the drug in HIV-1-infected peripheral blood mononuclear cells and MT-2 cells was directly related to the amount of intracellular A-80987. This study demonstrates that A-80987 binds to alpha 1 AGP, resulting in a free fraction below 10%. Cellular uptake of A-80987 is proportionally decreased in the presence of alpha 1 AGP, which results in less-than-expected antiviral activity. Importantly, we demonstrate for the first time that the inhibition of HIV protease is highly correlated with the amount of intracellular inhibitor.
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PMID:Human serum alpha 1 acid glycoprotein reduces uptake, intracellular concentration, and antiviral activity of A-80987, an inhibitor of the human immunodeficiency virus type 1 protease. 872 25

Rationally designed synthetic inhibitors of retroviral proteases inhibit the processing of viral polypeptides in cultures of human T lymphocytes infected with human immunodeficiency virus type 1 (HIV-1) and therefore suppress the infectivity of HIV-1 in vitro. We have previously reported the antiviral activity in vitro of HIV-1 protease inhibitors against the C-type retrovirus Rauscher murine leukemia virus (RMuLV) and the lentivirus simian immunodeficiency virus (SIV). The same compounds which blocked the infectivity of HIV-1 also inhibited the infectivity of RMuLV and SIV in vitro. This report extends these findings by testing the antiviral activity of HIV-1 protease inhibitors in vivo in the RMuLV model. RMuLV-infected mice were treated twice a day (bid) with either an active (SKF 108922) or inactive (SKF 109273) compound for fourteen days by the intraperitoneal (i.p.) route. Compared with excipient control, SKF 108922, formulated with hydroxypropyl-beta-cyclodextrin (HPB), reduced virus-induced splenomegaly, viremia, and serum reverse transcriptase (RT) levels, while SKF 109273 was inactive. The HPB vehicle by itself enhanced replication of RMuLV. The effects of changing the formulation and the route of administration were examined. SKF 108922, formulated in HPB, had similar antiviral activity when administered by the i.p. or subcutaneous (SC) routes. However, SKF 108922 administered as a colloidal suspension in cholesterol sulfate (CS) had no detectable antiviral effect. Measurements of the circulating levels of the protease inhibitor in plasma explained this result. Plasma concentrations of SKF 108922 exceeded 1000 nM within 10 min after SC administration of the compound solubilized in HPB, but SKF 108922 was not detected in plasma after SC administration of the same dose formulated with CS. Information on optimal conditions for administering these agents should prove useful in guiding their clinical application Therefore, RMuLV should provide a good model for the preclinical evaluation and development of this class of agents for the treatment of HIV.
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PMID:Effects of SKF 108922, an HIV-1 protease inhibitor, on retrovirus replication in mice. 873 97

The human immunodeficiency (HIV) codes for an aspartic protease known to be essential for retroviral maturation and replication. The HIV protease can recognize Phe-Pro and Tyr-Pro sequences as the virus-specific cleavage site. These features provided a basis for the rational design of selective HIV protease-targeted drugs for the treatment of acquired immunodeficiency syndrome (AIDS). HIV protease is formed from two identical 99 amino acid peptides. We replaced the two Cys residues by L-Ala to synthesize [Ala67,95]-HIV-1 protease by the solid phase method and then prepared [Tyr6,42, Nle36,46, (NHCH2COSCH2CO)51-52, Ala67,95] HIV-1 protease (NY-5 isolate) using the thioester chemical ligation method. Based on the substrate transition state, we designed and synthesized a novel class of HIV protease inhibitors containing an unnatural amino acid, (2S, 3S)-3-amino-2-hydroxy-4-phenylbutyric acid, named allophenylnorstatine (Apns) with a hydroxymethylcarbonyl (HMC) isostere. Among them, the conformationally constrained tripeptide kynostatin (KNI)-272 (iQoa-Mta-Apns-Thz-NHBut) was a highly selective and superpotent HIV protease inhibitor (Ki = 0.0055 nM). KNI-272 exhibited potent antiviral activities against both AZT-sensitive and -insensitive clinical HIV-1 isolates as well as HIV-2 with low cytotoxicity. After i.d. administration, bioavailability of KNI-272 was 42.3% in rats. Also, KNI-272 exhibited in vivo anti-HIV activities in human PBMC-SCID mice. The x-ray crystallography and molecular modeling studies showed that the HMC group in KNI-272 interacted excellently with the aspartic acid carboxyl groups of HIV protease active site in the essentially same hydrogen-bonding mode as the transition state. This result implies that the HMC isostere is an ideal transition-state mimic and contributes to the high activity of KNI-272.
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PMID:Design and synthesis of substrate-based peptidomimetic human immunodeficiency virus protease inhibitors containing the hydroxymethylcarbonyl isostere. 878 65

MK-639 (L-735,524) is a potent human immunodeficiency virus protease inhibitor under investigation in the treatment of acquired immunodeficiency syndrome. Five in vitro approaches have been used to identify the cytochrome P450 isoform(s) responsible for the human microsomal oxidative metabolism of MK-639. These approaches are: 1) chemical inhibition; 2) immunochemical inhibition; 3) metabolism by cDNA-expressed human cytochrome P450 enzymes; 4) a correlation analysis; and 5) competitive inhibition of marker activities. Ketoconazole and troleandomycin, both selective inhibitors for cytochrome P450 3A4 (CYP3A4), markedly inhibited the formation of all oxidative metabolites of MK-639; whereas other inhibitors (furafylline, sulfaphenazole, quinidine, S-mephenytoin, and diethyldithiocarbamate) had little effect on MK-639 metabolism. This suggested the involvement of CYP3A4 in MK-639 metabolism. Consistent with this, an anti-rat CYP3A1 rabbit polyclonal antibody, which shows a cross-reactive inhibition of CYP3A4-dependent testosterone 6beta-hydroxylation in human liver microsomes, completely inhibited MK-639 metabolism. Human recombinant CYP3A4 showed a high metabolic activity to form all MK-639 metabolites found in native human liver microsomes. In addition, the formation of individual MK-639 metabolites correlated well with each other and with testosterone 6beta-hydroxylation in 12 different human liver microsomes, whereas no correlation was observed between MK-639 metabolite formation and bufuralol 1'-hydroxylation (or tolbutamide methyl hydroxylation). Furthermore, MK-639 strongly inhibited testosterone 6beta-hydroxylation in a concentration-dependent manner. Kinetic analysis showed that MK-639 is a very potent competitive inhibitor for testosterone 6beta-hydroxylation, with a Ki value of approximately 0.5 mu M. Collectively, these results consistently indicate that CYP3A4 is the isoform responsible for the oxidative metabolism of MK-639 in human liver microsomes.
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PMID:Role of cytochrome P450 3A4 in human metabolism of MK-639, a potent human immunodeficiency virus protease inhibitor. 882 Apr 21

The bioavailability (BA) of a tripeptide protease inhibitor, KNI-272, which has a strong pharmacological potential for treating human immunodeficiency virus type 1 (HIV-1), has been studied in beagle dogs by administering several oral dosage forms. The tested dosage forms were form 1, plain gelatin capsules; forms 2 and 3, gelatin capsules of which the inner and outer surfaces were coated with 7G ethylcellulose (EC, 30 mu m thickness) and an enteric coating material, hydroxypropyl methylcellulose phthalate (HP-55), respectively; and form 4, gelatin capsules of which the inner surface is coated with 10G EC (60 mu m thickness). The difference between forms 2 and 3 was the amount of citric acid contained in the capsule, namely 100 mg in form 2 and 200 mg in form 3. One hundred milligrams of KNI-272 was placed in each capsule after being dissolved with propylene glycol (PG). These capsules were used to deliver KNI-272 to the stomach for form 1, to the upper part of the small intestine for forms 2 and 3, and to the middle part of the small intestine for form 4. As a reference, 50.0 mg of KNI-272 was administered to the same dogs by intravenous (IV) infusion for 15 min. By measuring the plasma drug levels with the HPLC method, BAs were estimated for each test dosage form. Form 1 showed the highest BA of 26 center dot 2 +/- 7 center dot 0% (mean +/- SE), though the other capsules showed BAs of approximately 10%, namely 6 center dot 6 +/- 0 center dot 4% for form 2, 10 center dot 3 +/- 1 center dot 1% for form 3 and 14 center dot 2 +/- 1 center dot 0% for form 4. Therefore, as the site where KNI-272 is released from the capsule becomes higher, the BA increases. In addition, as the amount of citric acid contained in a capsule increases, the BA value tends to increase. These results suggest that KNI-272 is stable and not extensively hydrolysed in the gut after oral administration, that the dissolution process into GI fluids is important for the BA of KNI-272, and that the most appropriate absorption site of KNI-272 in dogs is the duodenum. The potential of this new tripeptide compound as an orally active anti-AIDS drug has been confirmed.
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PMID:The bioavailability of oral dosage forms of a new HIV-1 protease inhibitor, KNI-272, in beagle dogs. 890 19

Patient human immunodeficiency virus type 1 (HIV-1) isolates that are resistant to protease inhibitors may contain amino acid substitutions L10I/V, M46L/I, G-48V, L63P, V82A/F/T, I84V, and L90M in the protease gene. Substitutions at positions 82 and/or 90 occur in variants that display high levels of resistance to certain protease inhibitors. Nucleotide substitutions at these two sites also lead to the loss of two HindII restriction enzyme digestion sites, and these changes make possible a rapid procedure for the detection of drug-resistant variants in patients on protease inhibitor therapy. This procedure was used to detect the emergence of mutated viruses at various times after the initiation of therapy with the HIV-1 protease inhibitor indinavir. The method includes viral RNA isolation from plasma and reverse transcription PCR amplification of the protease gene with fluorescence-tagged primers. The PCR product is digested with HindII, the cleavage products are separated on a urea-acrylamide gel in a DNA sequencer, and the extent of cleavage is automatically analyzed with commercially available software. In viruses from 34 blood samples from four patients, mutations leading to an amino acid change at residue 82 appeared as early as 6 weeks after the start of therapy and persisted throughout the course of the study period (48 weeks). Mutations leading to double substitutions at residues 82 and 90 were seen at a lower frequency and appeared later than the change at position 82. The changes detected by restriction enzyme cleavage were confirmed by DNA sequencing of the cloned protease genes by reverse transcription PCR amplification of viral RNA from isolates in plasma. In addition to the changes at positions 82 and 90, we have identified M46L/I, G48V, and I54V substitutions in isolates derived from indinavir-treated patients. HindII analysis of uncloned, PCR-amplified DNA offers a rapid screening procedure for the detection of virus isolates containing mutations at amino acid residues 82 and 90 in the HIV-1 protease gene. By using other restriction enzymes, the same method can be used to detect additional protease drug-resistant variants and is generally applicable for the detection of mutations.
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PMID:Emergence of protease inhibitor resistance mutations in human immunodeficiency virus type 1 isolates from patients and rapid screening procedure for their detection. 891 59

A novel tricyclic 21-amino-acid peptide, FR901724, was isolated from the cultured broth of Streptomyces sp. No. 73264. This peptide appears to possess potent anti-human immunodeficiency virus (HIV) activity in vitro and might represent a lead to a new class of anti-HIV agents; it qualifies as an HIV-cell fusion inhibitor because of its weak inhibition of virus-cell binding and strong inhibition of syncytium formation. From the time-of-addition experiments, the mode of action of FR901724 was found to definitely differ from that of KNI-272, a peptide mimetic allophenylnorstatine-derivative HIV protease inhibitor. FR901724 appears to interact with a stage of the virus replicative cycle that may well correspond to virus-cell fusion. We also found that FR901724 was synergistic or had a strong tendency toward synergism when combined with other antiviral drugs, such as KNI-272, AZT, ddI and dextran sulfate.
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PMID:FR901724, a novel anti-human immunodeficiency virus (HIV) peptide produced by Streptomyces, shows synergistic antiviral activities with HIV protease inhibitor and 2',3'-dideoxynucleosides. 892 10

CD8+ T lymphocytes may mediate important host responses to human immunodeficiency virus (HIV) infection by human leukocyte antigen (HLA)-restricted cytotoxicity and production of soluble HIV suppressor factors. CD8+ lymphocytes are also important for the suppression of many latent pathogens responsible for opportunistic disease in HIV-infected patients. There has been no systematic analysis of the responses of CD8+ lymphocyte counts to antiretroviral therapy. We compared CD8+ lymphocyte responses in seven trials of nucleoside or non-nucleoside analog reverse transcriptase inhibitors and in two trials of ritonavir, a HIV protease inhibitor. Nucleoside analog and non-nucleoside analog reverse transcriptase inhibitor monotherapy resulted in no substantial changes in CD8+ counts relative to baseline or placebo. Combination nucleoside analog therapy resulted in variable peak responses (-145 to +240 cells/mm3), which remained significantly above baseline for 0 to 12 weeks. In contrast, ritonavir monotherapy caused a peak increase of 892 CD8+ cells/mm3, which remained significantly above baseline for 32 weeks. There was a significant correlation (Rs 0.61, p = 0.01) between the peak CD4+ cell and CD8+ responses to each therapy, but no significant correlation between the peak viral load responses and peak CD8+ cell responses. These findings suggest that the greater CD8+ response seen with ritonavir may be due to its specific inhibition of HIV protease and also that the CD8+ response is dependent on new CD4+ cell production. The CD8+ lymphocyte proliferation observed with protease inhibitor therapy could result in improved suppression of HIV replication by the immune system and should be confirmed in a prospective trial comparing protease inhibitors with both nucleoside and non-nucleoside analog therapies.
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PMID:CD8+ lymphocyte responses to antiretroviral therapy of HIV infection. 970 47


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