Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) is an important target for chemotherapeutic agents used in the treatment of AIDS; the TIBO compounds are potent non-nucleoside inhibitors of HIV-1 RT (NNRTIs). Crystal structures of HIV-1 RT complexed with 8-Cl TIBO (R86183, IC50 = 4.6 nM) and 9-Cl TIBO (R82913, IC50 = 33 nM) have been determined at 3.0 A resolution. Mutant HIV-1 RT, containing Cys in place of Tyr at position 181 (Tyrl81Cys), is highly resistant to ...

Ritanserin is a potent and selective serotonin-S2 antagonist which slowly dissociates from the receptor sites, while setoperone has potent serotonin and moderate dopamine antagonistic properties and dissociates rapidly from the receptor sites. Acute administration of ritanserin (1–10 mg/kg) produced a non-competitive inhibition of 3H-ketanserin binding, measured ex vivo in washed frontal cortex membranes, which lasted for 12 h. This is in accordance with the slow dissociation of the drug ...

Recently developed agents specifically acting on different 5-hydroxytryptamine (5-HT) receptor populations were used to analyze the functional role of 5-HT2 receptor subtypes in the sleep-wakefulness cycle of the rat. The 5-HT2 receptor antagonist ritanserin injected intraperitoneally (IP) (0.04–2.5 mg/kg) induced an increase in deep slow wave sleep (SWS2) duration at the expense of wakefulness (W), light slow wave sleep (SWS1) and paradoxical sleep (PS). The stimulation of 5-HT2 ...

This study determined the limits of discriminability of cocaine HCl and the role of the training dose of cocaine in cocaine-saline discrimination. Rats were trained to discriminate 10 mg/kg of cocaine HCl from saline in a two-lever operant procedure, and then were retrained on progressively smaller doses of the training drug. Stimulus generalization experiments with test doses of cocaine 12 to 1250 times the training dose, were carried out each time the animals had reached criterion on ...

The experiments reported here were undertaken to examine the neuropharmacological characteristics of drugs inducing stimulus generalization with cocaine as a cue. Experiment 1 indicated that d-amphetamine (ED50: 0.17 mg/kg), 1-amphetamine (0.45 mg/kg), methylamphetamine (0.15 mg/kg), methylphenidate (0.55 mg/kg) and nomifensine (0.32 mg/kg) induce stimulus generalization with cocaine in rats trained to discriminate 10 mg/kg cocaine from saline; this generalization occurred in 100% of the ...

Ketanserin, a selective 5-HT2-receptor antagonist, inhibits the reversible aggregation induced by 5-hydroxytryptamine (5-HT) in human platelet-rich plasma (PRP). In this respect, the compound is equipotent to cyproheptadine and more active than methysergide (IC50: 1.66×10−8M, 1.44×10−8M and 5.62×10−8M respectively). Ketanserin is active against 5-HT-induced platelet aggregation after bothin vitro and oral administration to human volunteers. At concentrations up to 500 times in excess of ...

Monte Carlo (MC) simulations in combination with a linear response approach were used to estimate the free energies of binding for a series of 12 TIBO nonnucleoside inhibitors of HIV-1 reverse transcriptase. Separate correlations were made for the R6 and S6 absolute conformations of the inhibitors, as well as for the analogous N6-monoprotonated species. Models based upon the neutral unbound inhibitors produced overall better fits to experimental values than did those using the protonated ...

The effects of four reference antihistamines: ketotifen, diphenhydramine, chlorpheniramine and pyrilamine and of astemizole, a new potent and long-acting antihistamine, were studied on 16 hr sleep-wakefulness patterns in the same dogs. Using a computer-based on-line analysis and automatic stage classification, a differentiation was made between wakefulness, transition to sleep (drowsiness), slow wave sleep and rapid eye movement (REM) sleep. The reference antihistamines significantly ...

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are potent inhibitors of human immunodeficiency virus type 1 (HIV-1); however, currently marketed NNRTIs rapidly select resistant virus, and cross-resistance within the class is extensive. A parallel screening strategy was applied to test candidates from a series of diarylpyrimidines against wild-type and resistant HIV strains carrying clinically relevant mutations. Serum protein binding and metabolic stability were addressed early ...