Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The bisheteroarylpiperazines (BHAPs) are potent inhibitors of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) and specifically block HIV-1 replication (Romero, D. L., Busso, M., Tan, C.-K., Reusser, F., Palmer, J. R., Poppe, S. M., Aristoff, P. A., Downey, K. M., So, A. G., Resnick, L., and Tarpley, W. G. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 8806-8810). Here we show that the radiolabeled BHAP [3H]U-88204 binds specifically to HIV-1 RT with high affinity (KD of 50 nM) and a stoichiometry of 1 mol of U-88204 per 1 mol of p66/p51 RT heterodimer. Binding of [3H]U-88204 to RT is unaffected by the presence of saturating poly(rC).oligo (dG)12-18 template-primer. Direct measurement of competition between [3H]U-88204 and other RT inhibitors for binding to RT reveals mutually exclusive competition between [3H]U-88204 and the non-nucleoside RT inhibitor BI-RG-587 (Kopp, E. B., Miglietta, J. J., Shrutkowski, A. G., Shih, C.-K., Grob, P. M. and Skoog, M.T. (1991) Nucleic Acids Res. 19, 3035-3039), indicating that both share the same binding site. Phosphonoformate in concentrations up to 50 microM shows no competition with [3H]U-88204 for binding to RT either alone or in the presence of template-primer. Dideoxynucleotide RT inhibitors affect the binding of [3H]U-88204 to RT when complementary template-primer is present. [3H]U-88204 and the dideoxynucleotide ddGTP can bind RT simultaneously, but the presence of one ligand decreases the affinity of RT for the second. Inasmuch as ddGTP approximates the nucleotide substrate of RT, the direct demonstration of an RT-dideoxynucleotide-[3H]U-88204 complex validates the use of indirect kinetic methods to assess the strength of BHAP interaction with RT and suggests that RT inhibition by U-88204 is achieved via effects on nucleotide substrate binding.
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PMID:The binding of a novel bisheteroarylpiperazine mediates inhibition of human immunodeficiency virus type 1 reverse transcriptase. 137 Apr 45

The pharmacokinetics of thiophosphonoformate (TPFA) and phosphonoformate (foscarnet, PFA) were studied in normal adult cats, a species susceptible to feline immunodeficiency virus (FIV) infection. Parent drugs and metabolites were quantitated by high-performance liquid chromatography (HPLC). TPFA had a mean terminal plasma half-life of 42 min, a total clearance of 4.58 ml/min/kg, and a renal clearance of 1.24 ml/min/kg (N = 4). TPFA underwent in vivo metabolism to PFA and thiophosphonic acid (TPA); the latter was inactive against HIV reverse transcriptase. The 6-h cumulative urinary excretion was 42.3% of the intravenous administered dose of TPFA, consisting of 23.5% unchanged TPFA, 13.8% PFA, and 5.0% TPA. In comparison, PFA had a mean (N = 5) terminal half-life of 172 min and a total clearance of 1.88 ml/min/kg, approximating its renal clearance. There was no evidence of PFA metabolism. Oral doses of TPFA were administered either in enteric-coated capsules or in solution by gavage. The mean oral bioavailability of encapsulated TPFA and PFA was 22 and 8%, respectively. When given by gavage, TPFA had a higher mean bioavailability (33%), but with a greater variability. Based on the 6-h cumulative urinary excretion of TPFA, the mean oral bioavailability of TPFA was 44%, similar to that based on plasma data. The TPFA appears to be superior to PFA because of its greater oral bioavailability and its ability to deliver an active metabolite, PFA, to the systemic circulation after oral dosing.
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PMID:Pharmacokinetics of potential anti-AIDS agents thiofoscarnet and foscarnet in the cat. 138 17

A modified tetrazolium-based colorimetric assay was used to determine the anti-HIV activities of ddAzThd, ddCyd, ddIno, and PFA. In this assay, poly-1-lysine-coated plates were used to attach the MT-2 cells to the bottom of the plates. A fixed amount of virus (50 TCID50) was used in each well. A modified version of the formula published by Pauwels et al. (1988) was used for calculating the percentage cell protection from virus infection. Using CC10/EC90 to calculate the selective indices, the decreasing order of selectivity against HIV-1 strain A87SF, was: ddAzThd greater than PFA greater than ddCyd greater than ddIno. Against HIV-1 strain A79SK-1 the decreasing order of selectivity was: PFA greater than ddIno greater than AzThd greater than ddCyd. The modified formula showed lack of anti-HIV activity for thymidine at non-toxic concentrations.
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PMID:Modified tetrazolium-based colorimetric method for determining the activities of anti-HIV compounds. 166 34

Various combinations of inhibitors of HIV reverse transcriptase were tested for inhibition of HIV replication in order to reveal any potential synergism or antagonism. PFA, a pyrophosphate analogue, gave synergistic inhibition of HIV replication in combination with both of the thymidine analogues AZT and FLT. The combination of PFA and AZT-TP gave only additive or weakly synergistic inhibition in a reverse transcriptase enzyme assay. The combination of AZT and FLT also gave synergistic inhibition of HIV replication, whilst the combination of AZT-TP and FLT-TP gave only additive or weakly synergistic inhibition of reverse transcriptase. Thus, the synergy does not arise from effects on reverse transcriptase alone but must be owing to other, cellular factors, such as effects on nucleoside metabolism or metabolism of the analogues. The results are consistent with the hypothesis that AZT may have an alternative mechanism of inhibition other than inhibition of reverse transcriptase. The diminished cytotoxicity observed in addition to the synergistic inhibition makes these combinations attractive from the point of view of combination chemotherapy. The inhibition of HIV replication by peptides from various parts of the V3 region of gp120 whose sequences were homologous with the tryptase inhibitor trypstatin was tested. Inhibitory activity was displayed by two peptides containing cysteine in their sequence. Antibodies to two peptides containing the two conserved cysteine residues from opposite sides of the neutralizing loop of gp120 were previously associated with protection from vertical transmission of HIV. The V3 region thus seems to be important for the function of gp120 and the transmission of HIV.
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PMID:Synergistic combinations and peptides in the inhibition of human immunodeficiency virus. 171 18

Potential specific inhibitors of HIV RNA-dependent DNA polymerase (RDDP) were examined in an in-vitro test system containing purified HIV-1 RDDP, or functionally purified cellular DNA-dependent DNA polymerases alpha, beta and gamma. A wide variety of drugs were tested for their specific inhibitory activity against the viral enzyme to identify substances which, at the same concentration, did not inhibit the cellular DNA polymerases. Phosphonoformic acid and derivatives were found to be the most specific inhibitors, followed by chlortetracycline.
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PMID:Inhibition of HIV-1 RNA-dependent DNA polymerase and cellular DNA polymerases alpha, beta and gamma by phosphonoformic acid and other drugs. 245 49

To investigate the pharmacokinetics and effects of intravenous foscarnet, 13 relatively healthy male patients with human immunodeficiency virus infection and a mean CD4+ lymphocyte value of 0.45 x 10(-9) cells per liter were given a continuous intravenous infusion of foscarnet (0.14 to 0.19 mg/kg per min) for 8 to 21 days. Blood and urine samples were taken during and after drug administration to monitor foscarnet concentrations. Lumbar puncture was performed during the infusion in five patients. The concentrations in plasma showed large variations both within and between patients. The disposition of foscarnet could be explained by a triexponential equation (t1/2 lambda 1, 0.40 to 2.52 h; t1/2 lambda 2, 3.20 to 16.7 h; t1/2 lambda 3, 36 to 196 h). Renal clearance accounted for most of the plasma clearance, the difference probably reflecting the passage of foscarnet into bone. Up to 20% of the cumulative dose may have been deposited in bone 7 days postinfusion. Foscarnet was distributed to the cerebrospinal fluid in a concentration varying from 13 to 68% of the simultaneous concentration in plasma. Polyuria and polydipsia were recorded in all patients. There appears to be an association between the degree of malaise, including symptoms such as nausea, vomiting, fatigue, and headache, and concentrations in plasma above 350 mumol/liter.
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PMID:Pharmacokinetics of foscarnet and distribution to cerebrospinal fluid after intravenous infusion in patients with human immunodeficiency virus infection. 252 39

Phosphonoformate (PFA; a pyrophosphate analogue) is an effective inhibitor of the reverse transcriptase enzyme in many animal retroviruses. In vitro studies have shown that PFA is also an effective inhibitor of HIV (HTLV III/LAV) at doses readily attainable in vitro. A pilot study was therefore performed with a 3-week intravenous infusion of PFA in 11 patients with AIDS and AIDS-related complex (ARC). Viral isolations were performed before and at regular intervals up to 3 months post-infusion on treated patients, as well as on four untreated control patients. Virus isolation was negative after therapy in eight patients, six of whom were negative throughout the follow-up period. Virus was isolated on 70% of attempts from the four control subjects and on 20% of attempts from treated subjects. Three patients showed an improvement in delayed hypersensitivity responses. No obvious improvement was seen in patients' OKT4 positive lymphocyte counts. Treatment was not limited by side-effects with the exception of one patient who developed an axillary vein thrombosis within 4 days of treatment via a subclavian line. Treatment was therefore discontinued following administration of only one dose and the patient was excluded from further study. A further patient had reversible renal dysfunction. Other side-effects were minor, consisting of headache or thrombophlebitis at the site of infusion. These results suggest that a further trial with PFA administered over a longer period and with a longer follow-up period in AIDS and ARC patients may be warranted, particularly if an oral preparation becomes available.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Phosphonoformate (foscarnet): a pilot study in AIDS and AIDS related complex. 296 89

Foscarnet was administered by continuous intravenous infusion in 15 patients with the acquired immunodeficiency syndrome (AIDS) in an open, uncontrolled study. Mean steady state serum concentrations of foscarnet was 261 mumol/l. Treatment was given for 6-21 days, median 14 days, being interrupted prematurely due to renal function impairment in seven patients, and due to other reasons in three patients. Foscarnet therapy was accompanied by improvement of some, probably cytomegalovirus (CMV) related, symptoms but did not otherwise affect the clinical condition of the patients. The occurrence of positive CMV cultures decreased significantly during therapy. Human immunodeficiency virus (HIV) detection by culture was positive in 70-80% of cultures and was unaffected by foscarnet treatment. Eight patients had detectable, free HIV antigen in serum before therapy, and in five of these HIV antigen disappeared during therapy, but reappeared 4-23 weeks after therapy. No patient lost HIV antigen, except during foscarnet therapy. No patient became HIV antigen positive during foscarnet therapy. Immunological parameters did not change during or after foscarnet therapy. Renal function impairment was seen in 9 patients (95% confidence limits, 32-84%), apparently due to reversible tubular damage. At follow-up, serum creatine was normal in all surviving patients. Concomitant medication may have contributed to the renal side-effects. Severe renal function impairment, i.e. serum creatinine above 0.25 mumol/l, was only seen in patients who at the start of foscarnet therapy were chronically affected by their disease. Thus, foscarnet reduces HIV antigen production in AIDS patients. Renal function impairment limits foscarnet use in AIDS patients, but in individuals with less severe manifestations of HIV infection, this side effect may be less frequent.
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PMID:The effect of foscarnet (phosphonoformate) on human immunodeficiency virus isolation, T-cell subsets and lymphocyte function in AIDS patients. 296 90

Antiviral agents under investigation for the treatment of patients infected with the human immunodeficiency virus (HIV) are reviewed. Multiple mechanisms exist by which antiviral agents might inhibit the replication of HIV or eradicate its latent form in affected cells, or both. These mechanisms include (1) interference with the cell surface receptor for HIV, (2) prevention of uncoating of viral particles, (3) inhibition of reverse transcriptase, (4) prevention of integration and posttranscription processing, (5) interference with viral assembly, and (6) interference with virus release. Most agents developed thus far work by inhibiting HIV reverse transcriptase. Suramin, ribavirin, ammonium 21-tungsten-9-antimoniate (HPA-23), foscarnet (phosphonoformate, PFA), inosine pranobex (isoprinosine), peptide T, ampligen, AL 721, dideoxycytidine, and zidovudine (formerly azidothymidine) have antiretroviral activity in vitro. To date zidovudine is the only antiretroviral agent approved by the FDA as clinically effective. However, zidovudine has serious toxicities, including neutropenia and anemia; in some patients dosage reduction or cessation of therapy may be necessary. Because treatment with zidovudine does not cure HIV infection, numerous studies are under way with other anti-HIV agents. Ultimately, combinations of agents probably will be used to suppress or eradicate HIV. While the search for more efficacious and less toxic treatments continues, the development of zidovudine in such a short time provides hope that progress toward a cure will be made rapidly.
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PMID:Development of antiviral agents for the treatment of human immunodeficiency virus infection. 332 38

The inhibitory activities of human immunodeficiency virus reverse transcriptase (HIV-RT) inhibitors PFA and Suramin against HIV-RT and equine infectious anemic virus reverse transcriptase (EIAV-RT) were studied in this paper. The 50% inhibitory concentration (IC50) of HIV-RT and EIAV-RT treated by PFA and Suramin were 0.2 mumol, 9.8 mumol and 17 mumol, 19.9 mumol, respectively. More than thirty Chinese medicines, including recipes, herbs, extracts of traditional materia medica and isolated compounds were tested using HIV-RT and EIAV-RT as target enzymes. It was found that 5 crude extracts such as Rhizoma Polygoni Cuspidati, and Radix Notoginseng, 7 isolated compounds like Flavone of Ramulus Visci, Flavone of Ajuga Decumbens Thumb, and Aristolochic acid, as well as the extract of the complex prescription Xiao Chai Hu Tang have shown various inhibitory actions on these two enzymes. The activities of the two enzymes were comparable, but HIV-RT was more sensitive, suggesting that HIV-RT can be used as index for the screening of anti-aids drugs.
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PMID:Screening anti-HIV Chinese materia medica with HIV and equine infectious anemic virus reverse transcriptase. 751 33


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