Prospecting for an HIV vaccine.

Human immunodeficiency virus (HIV) sets several challenges for the development of a preventative HIV vaccine. Predictable, protective natural immunity against HIV does not occur and so unlike most other diseases for which vaccines exist, there are few guideposts from natural infection. Nonetheless, six vaccine efficacy trials have occurred. One in particular, the Thai trial called RV144, showed partial protective efficacy and potential ways ahead to a better vaccine approach. This coupled with other lessons from studies of acute infections as well as an increasingly complex knowledge of HIV-related vaccine immunology bring hope that a vaccine solution might be reached for this pervasive and deadly pandemic.

Are you PEPped and PrEPped for travel? Risk mitigation of HIV infection for travelers.

The HIV pandemic persists globally and travelers are at risk for infection by the Human Immunodeficiency Virus (HIV). While HIV-focused guidelines delineate risk stratification and mitigation strategies for people in their home communities, travel issues are not addressed. In this review, direct and indirect evidence on HIV risk among travelers is explored. The burgeoning practice of employing pre-exposure prophylaxis (PrEP) with anti-retroviral therapy in the non-travel setting is introduced, as well as the more established use of post-exposure prophylaxis (PEP). Challenges in applying these lessons to travelers are discussed, and a new guidelines process is scoped and recommended.

Verbal learning and memory deficits in traumatic brain injury: encoding, consolidation, and retrieval.

The present study examined the nature of verbal memory deficits in individuals with traumatic brain injury (TBI) compared to healthy controls. The study was designed to control for methodological shortcomings of previous related research. Three groups of participants were used: (a) a head injured sample with moderate to severe traumatic brain injuries (N=55), (b) a control sample matched on age and initial performance on CVLT Trial 5 and Sum of Trials 1 to 5 (N=55), and (c) a control sample matched on age, education, and race, but not on initial CVLT learning performance (N=55). Current findings indicate that: (a) rate of learning was comparable across groups, consistent with no encoding differences, (b) TBI patients have a significantly more rapid rate of forgetting of new information than either acquisition-matched or demographic-matched controls, consistent with consolidation problems in TBI, (c) TBI patients have less proactive interference than demographic-matched control participants, consistent with a consolidation problem in the TBI group, (d) TBI patients and acquisition-matched controls have comparably low rates of proactive interference, consistent with impaired acquisition in both of these groups, and (e) TBI patients and controls do not differ in the benefit experienced from semantic or recognition retrieval cues, consistent with no differences in retrieval processes. These data support an impaired consolidation hypothesis, rather than encoding or retrieval deficits, as the primary deficit underlying memory impairment in TBI.

3-Aryl-1,2-diacetamidopropane derivatives as novel and potent NK-1 receptor antagonists.

Early structure-activity studies on racemic tryptophan ester and amide NK-1 antagonists 5-7 led to the discovery that the potency of the series could be markedly increased by moving the carbonyl function in these molecules to an off-chain position as in the 3-aryl-1,2-diacetamidopropane 9. Further medicinal chemistry incorporating this change resulted in the discovery of a novel series of highly potent aryl amino acid derived NK-1 antagonists of the R stereoisomeric series (IC50's = 100 pM to > 5 microM). Compounds in this series were shown to be competitive antagonists using an in vitro NK-1 smooth muscle assay, and this data correlated well with observed human NK-1 binding affinities. Two of these agents, (R)-25 and (R)-32, blocked intrathecal NK-1 agonist-driven [Ac-[Arg6,Sar9,Met(O2)11]- substance P 6-11 (Ac-Sar9)] nociceptive behavior in mice. Both compounds potently blocked the neurogenic dural inflammation following trigeminal ganglion stimulation in the guinea pig after intravenous administration. Further, upon oral administration in this model, (R)-32 was observed to be very potent (ID50 = 91 ng/kg) and have a long duration of action (> 8 h at 1 micrograms/kg). Compound (R)-32, designated LY303870, is currently under clinical development as an NK-1 antagonist with a long duration of action.

Antiestrogens. 3. Estrogen receptor affinities and antiproliferative effects in MCF-7 cells of phenolic analogues of trioxifene, [3,4-dihydro-2-(4- methoxyphenyl)-1-naphthalenyl][4-[2-(1-pyrrolidinyl)ethoxy]- phenyl]methanone.

Benzothiophenes 3 and 4, derived from the acrylophenone antiestrogen trioxifene (2), are characterized by high estrogen receptor (ER) affinity and low residual estrogenicity compared to tamoxifen (1a). In order to characterize further the growth suppression mechanism for these structural types we have prepared structural variants of 2 bearing hydroxy groups positioned to maximize ER affinity. Thus, dihydronaphthalenes 5 and 6 and benzofluorenes 7 and 8 were prepared and studied in MCF-7 human breast cancer cells, in comparison with 3 and 4. All compounds were powerful suppressants of cell growth, with 50% inhibition ranging from 4.5 to 160 nM. Greatest potency was seen with diphenols 6 and 8. These compounds had intracellular ER affinities ranging from 0.2 to 4.1% of that of estradiol, suggestive of a potential for partial agonist effects. Simultaneous exposure of cells to 0.1 microM concentrations of estradiol and 3 or 4 did not affect the degree of growth inhibition seen with 0.1 microM 3 or 4 alone. Partial reversal of inhibition occurred when 0.1 microM 5-8 were each accompanied by 0.1 microM estradiol. Under these conditions complete reversal of growth inhibition has been found with 1a, 1b, and other triarylethylenes. Calmodulin, a putative target for triarylethylenes, and which is antagonized by 1a, was shown to interact weakly with 7 and 8 and not at all with 3-6. These results suggest that MCF-7 cell growth suppression by 3-8 may be due to interaction with unidentified receptors besides ER and extend earlier findings indicating that events occurring after interaction of these compounds with ER differ from those of triarylethylene antiestrogens.

Novel agents effective against solid tumors: the diarylsulfonylureas. Synthesis, activities, and analysis of quantitative structure-activity relationships.

A series of diarylsulfonylureas with exceptionally broad-spectrum activity against syngeneic rodent solid tumors in vivo is described. Their discovery resulted from a program dedicated to in vivo screening for novel oncolytics in solid tumor models, rather than traditional ascites leukemia models. The structures, oral efficacy, side-effect profile, and mechanism of action of these sulfonylureas appear to be distinct from previously known classes of oncolytics. An extensive series of analogues was prepared to probe structure-activity relationships (SAR), with particular focus on the substituent patterns of each aryl domain. Quantitative analysis of these substituent SARs, using the method of cluster significance analysis, showed the lipophilicity of the substituents to be the dominant determinant of activity. One compound from the series, LY186641 (104, sulofenur), has progressed to Phase I clinical trials as an antitumor drug.

3-Sulfonyl-1-carba-1-dethiacephems.

The stability of the 1-carba-1-dethiacephalosporin framework has allowed the synthesis of a range of 3-sulfonyl-1-carba-1-dethiacephems unavailable for a variety of reasons in the cephem arena. The known p-nitrobenzyl 7 beta-(phenoxyacetamido)-3-[[(trifluoromethyl)sulfonyl]oxy]-1-carba -1- dethia-3-cephem-4-carboxylate served as a precursor to this series of compounds. Displacement of the enol triflate with various sulfinates in acetonitrile or DMF and deprotection of the intermediates led to 7 beta-[(2-amino-4-thiazolyl)(methoxyimino)acetyl]amino]- 3-[alkyl(aryl)sulfonyl]-1-carba-1-dethia-3-cephem-4-carboxyl ic acids. The 3-sulfonyl-1-carba-1-dethiacephems display potent activity against both Gram-positive and Gram-negative bacteria. The following MIC's (microgram/mL) for the 3-cyclopropyl sulfone are representative: Staphylococcus aureus = 4, Streptococcus pyogenes = 1, Haemophilus influenzae = 0.25, Escherichia coli = 0.03, Enterobacter cloacae = 0.25, Proteus rettgeri = 0.25. The excellent in vitro antibacterial activity of this series indicates the potential of the carbacephalosporin framework for exploring substituents which are unknown or which produce unstable cephems.

Synthesis and evaluation of the antiovulatory activity of a variety of melatonin analogues.

A series of melatonin analogues was synthesized and examined for ovulation-blocking activity. Deviation from the 5-methoxy group or substitution of the 1 position prevented activity. Activity was not particularly sensitive to minor variations in the N-acyl group nor was it significantly altered by methylation of position 2 or the alpha-methylene; however, a pronounced enhancement resulted from halogenation of the 6 position.