ABSTRACT
Poly(1-methyl-6-thioinosinic acid), or PMTI, is a single-stranded polyribonucleotide and is the first homopolyribonucleotide devoid of Watson-Crick hydrogen bonding sites to show potent human immunodeficiency virus (HIV) inhibition. PMTI was found to be active when evaluated against a variety of low passage clinical HIV isolates in fresh human peripheral blood cells, including T cell-tropic and monocyte-macrophage-tropic viruses, syncytium-inducing and non-syncytium-inducing viruses and viruses representative of the various HIV-1 clades (A through F). The compound was active against HIV-2, all nucleoside and non-nucleoside reverse transcriptase (RT) inhibitor drug-resistant virus isolates tested and interacted with AZT or ddl to synergistically inhibit HIV infection. In biochemical inhibition assays, PMTI was determined to be a potent inhibitor of HIV-1 and HIV-2 RT, including RTs with mutations that engender resistance to nucleoside and non-nucleoside RT inhibitors. PMTI inhibited both the polymerase and RNase H activities of HIV RT. PMTI did not inhibit HIV-1 protease or integrase. Cell-based mechanism of action assays indicated that PMTI also interfered with early events in the entry of HIV into target cells. Furthermore, PMTI inhibited the fusion of gp120-expressing and CD4-expressing cells, but at concentrations approximately 1 log10 greater than those that inhibited virus entry. These results suggest that the homopolyribonucleotide PMTI blocks HIV replication in human cells at its earliest stages by multiple mechanisms, inhibition of virus entry and inhibition of RT.
Subject(s)
HIV-1/drug effects , Poly I/chemistry , Poly I/pharmacology , Thionucleotides/chemistry , Thionucleotides/pharmacology , Virus Replication/drug effects , Anti-HIV Agents/chemistry , Anti-HIV Agents/pharmacology , HIV Infections/drug therapy , HIV Infections/virology , HIV Reverse Transcriptase/antagonists & inhibitors , HIV-1/enzymology , HeLa Cells , Humans , Reverse Transcriptase Inhibitors/chemistry , Reverse Transcriptase Inhibitors/pharmacology , Tumor Cells, CulturedABSTRACT
The structure-activity relationships of a series of compounds related to the nonnucleoside reverse transcriptase (RT) inhibitor (NNRTI) oxathiin carboxanilide have been described (R. W. Buckheit, Jr., T. L. Kinjerski, V. Fliakas-Boltz, J. D. Russell, T. L. Stup, L. A. Pallansch, W. G. Brouwer, D. C. Dao, W. A. Harrison, R. J. Schultz, J. P. Bader, and S. S. Yang, Antimicrob. Agents Chemother. 39:2718-2727, 1996). From these studies, the furanyl-containing analog UC10 was identified as the most potent inhibitor of human immunodeficiency virus type 1 (HIV-1) replication and a promising candidate for further development. Three new UC analogs (UC040, UC82, and UC781) have been determined to inhibit laboratory-derived and low-passage-number, primary virus isolates at low nanomolar concentrations in both established and fresh human cells. Each of the compounds synergistically interacted with the nucleoside analogs zidovudine, dideoxyinosine, dideoxycytosine, and lamivudine to inhibit HIV-1 replication. As a group, the UC compounds were found to be less active against viruses with the L100I, K103N, and Y181C amino acid changes in the RT and, upon in vitro selection, yielded resistant virus with the Y181C mutation in the RT. The most potent of the three new compounds, UC781, contains a furanyl side chain, similar to UC10, but differs in having an extended ether side chain instead of an oxime chain. The broad therapeutic index of UC781 (>62,000) resulted in effective inhibition of NNRTI-resistant virus isolates at high nanomolar concentrations. Furthermore, UC781 and the NNRTI costatolide were able to synergistically inhibit HIV-1 replication when used in combination, suggesting that UC781 may interact with the RT differently than the other UC analogs. The favorable anti-HIV properties of the UC compounds suggest they should be considered for further clinical development.
Subject(s)
Anti-HIV Agents/pharmacology , Carboxin/pharmacology , HIV-1/drug effects , Reverse Transcriptase Inhibitors/pharmacology , Carboxin/analogs & derivatives , Carboxin/pharmacokinetics , Cells, Cultured , Drug Resistance, Microbial , Drug Synergism , HIV Reverse Transcriptase/genetics , HIV-1/genetics , Humans , Microbial Sensitivity Tests , Mutation , Reverse Transcriptase Inhibitors/pharmacokinetics , Structure-Activity RelationshipABSTRACT
Many products and materials are available in the widely used pressurized package or "aerosol" form. A simulated breathing zone model approach has been developed and used to characterize the particles to which a user may be exposed. Some products characterized under simulated "worst reasonable" conditions produced concentrations of particulates smaller than 6 micrometer aerodynamic diameter exceeding 50 mg/m3.
Subject(s)
Aerosols , Air Pollutants/analysis , Household Products , Respiration , HumansABSTRACT
The many products available in pressurized packages produce appreciable concentrations of particulates that may be deposited in the deep lung of human users. We have reported the size and concentration characteristics of these aerosols under carefully standardized conditions in a previous paper. These standard conditions have been varied to determine the influence of product discharge conditions on observed aerosol characteristics. The size characteristics are relatively insensitive to a wide range of changes in the discharge conditions; the only significant effect observed followed changing the target of the spray from a steel plate to a wig. The aerosol concentrations were changed by several experimental factors, but the relative changes were less than the estimated relative range of human exposure.
