Exploring isoxazoles and pyrrolidinones decorated with the 4,6‐dimethoxy‐1,3,5‐triazine unit as human farnesyltransferase inhibitors

Unprecedented triazinyl‐isoxazoles were afforded via an effective cycloaddition reaction between nitrile oxides and the scarcely described 2‐ethynyl‐4,6‐dimethoxy‐1,3,5‐triazine as dipolarophile. The biological evaluation of the newly synthesized compounds showed that the inhibition of human farnesyltransferase by zinc complexation could be improved with triazine‐isoxazole moieties. The replacement of the isoxazole unit by a pyrrolidin‐2‐one was detrimental to the inhibitory activity while the pyrrolidin‐2‐thione derivatives conserved the biological potential. The potential of selected compounds to disrupt protein farnesylation in Chinese hamster ovary (CHO) cells transfected with pEGFP‐CAAX was also evaluated.     

Identification of a new chemical class of antimalarials

The increasing spread of drug-resistant malaria strains underscores the need for new antimalarial agents with novel modes of action (MOAs). Here, we describe a compound representative of a new class of antimalarials. This molecule, ACT-213615, potently inhibits in vitro erythrocytic growth of all tested Plasmodium falciparum strains, irrespective of their drug resistance properties, with half-maximal inhibitory concentration (IC(50)) values in the low single-digit nanomolar range. Like the clinically used artemisinins, the compound equally and very rapidly affects all 3 asexual erythrocytic parasite stages. In contrast, microarray studies suggest that the MOA of ACT-213615 is different from that of the artemisinins and other known antimalarials. ACT-213615 is orally bioavailable in mice, exhibits activity in the murine Plasmodium berghei model and efficacy comparable to that of the reference drug chloroquine in the recently established P. falciparum SCID mouse model. ACT-213615 represents a new class of potent antimalarials that merits further investigation for its clinical potential.     

Context and dating of Aurignacian vulvar representations from Abri Castanet, France

We report here on the 2007 discovery, in perfect archaeological context, of part of the engraved and ocre-stained undersurface of the collapsed rockshelter ceiling from Abri Castanet, Dordogne, France. The decorated surface of the 1.5-t roof-collapse block was in direct contact with the exposed archaeological surface onto which it fell. Because there was no sedimentation between the engraved surface and the archaeological layer upon which it collapsed, it is clear that the Early Aurignacian occupants of the shelter were the authors of the ceiling imagery. This discovery contributes an important dimension to our understanding of the earliest graphic representation in southwestern France, almost all of which was discovered before modern methods of archaeological excavation and analysis. Comparison of the dates for the Castanet ceiling and those directly obtained from the Chauvet paintings reveal that the "vulvar" representations from southwestern France are as old or older than the very different wall images from Chauvet.     

Antigen stored in dendritic cells after macropinocytosis is released unprocessed from late endosomes to target B cells

B lymphocytes can be triggered in lymph nodes by nonopsonized antigens (Ag), potentially in their native form. However, the mechanisms that promote encounter of B lymphocytes with unprocessed antigens in lymph nodes are still elusive. We show here that antigens are detected in B cells in the draining lymph nodes of mice injected with live, but not fixed, dendritic cells (DCs) loaded with antigens. This highlights active processes in DCs to promote Ag transfer to B lymphocytes. In addition, antigen-loaded DCs found in the draining lymph node were CD103+. Using 3 different model Ag, we then show that immature DCs efficiently take up Ag by macropinocytosis and store the internalized material in late endocytic compartments. We find that DCs have a unique ability to release antigens from these compartments in the extracellular medium, which is controlled by Rab27. B cells take up the regurgitated Ag and the chemokine CXCL13, essential to attract B cells in lymph nodes, enhances this transfer. Our results reveal a unique property of DCs to regurgitate unprocessed Ag that could play an important role in B-cell activation.