The anthelmintic praziquantel is a human serotoninergic G-protein-coupled receptor ligand

Schistosomiasis is a debilitating tropical disease caused by infection with parasitic blood flukes. Approximately 260 million people are infected worldwide, underscoring the clinical and socioeconomic impact of this chronic infection. Schistosomiasis is treated with the drug praziquantel (PZQ), which has proved the therapeutic mainstay for over three decades of clinical use. However, the molecular target(s) of PZQ remain undefined. Here we identify a molecular target for the antischistosomal eutomer — (R)-PZQ — which functions as a partial agonist of the human serotoninergic 5HT_2B receptor. (R)-PZQ modulation of serotoninergic signaling occurs over a concentration range sufficient to regulate vascular tone of the mesenteric blood vessels where the adult parasites reside within their host. These data establish (R)-PZQ as a G-protein-coupled receptor ligand and suggest that the efficacy of this clinically important anthelmintic is supported by a broad, cross species polypharmacology with PZQ modulating signaling events in both host and parasite.

Schistosomiasis is caused by infection with the flatworm Schistosoma, and praziquantel is the drug of choice for its treatment. Here, Chan and colleagues identify praziquantel as a ligand for the human serotoninergic 5-HT_2B G-protein-coupled receptor, and reveal a function for praziquantel as a regulator of vascular tone in treated hosts.

In-house and synchrotron X-ray diffraction studies of 2-phenyl-1,10-phenanthroline, protonated salts, complexes with gold(III) and copper(II), and an orthometallation product with palladium(II)

Different salts of the 2-phenyl-1,10-phenanthrolin-1-ium cation, (pnpH)(+), are obtained by reacting 2-phenyl-1,10-phenanthroline (pnp), C18H12N2, (I), with a variety of anions, such as hexafluoridophosphate, C18H13N2(+)·PF6(-), (II), trifluoromethanesulfonate, C18H13N2(+)·CF3SO3(-), (III), tetrachloridoaurate, (C18H13N2)[AuCl4], (IV), and bromide (as the dihydrate), C18H13N2(+)·Br(-)·2H2O, (V). Compound (I) crystallizes with Z' = 2, with both independent molecules adopting a coplanar conformation. In (II)-(IV), a hydrogen bond exists between the cation and anion, while one of the lattice water molecules serves as a hydrogen-bonded bridge between the cation and anion in (V). Reaction of (I) with HAuCl4 gives the salt complex (IV); however, reaction with KAuCl4 produces the monodentate complex trichlorido(2-phenyl-1,10-phenanthroline-κN(10))gold(III), [AuCl3(C18H12N2)], (VI). Dichlorido(2-phenyl-1,10-phenanthroline-κ(2)N,N')copper(II), [CuCl2(C18H12N2)], (VII), results from the reaction of CuCl2·2H2O and (I), in which the Cu(II) center adopts a tetrahedrally distorted square-planar geometry. The pendent phenyl ring twists to a bisecting position relative to the phenanthroline plane. The square-planar Pd(II) complex, bromido[2-(phenanthrolin-2-yl)phenyl-κ(3)C(1),N,N']palladium(II), [PdBr(C18H11N2)], (VIII), is obtained from the reaction of (I) with [PdCl2(cycloocta-1,5-diene)], followed by addition of bromine. A coplanar geometry for the pendent ring is adopted as a result of the tridentate bonding motif.

Bacterial meningitis in infants: sonographic features

Twenty-three infants with clinically proven bacterial meningitis were studied with real-time cranial sonography at the time of initial diagnosis and in several cases subsequently. A spectrum of sonographic abnormalities was observed, including bright convolutional markings, focal or diffuse increased and/or decreased parenchymal echoes, ventricular debris, and hydrocephalus. In three infants with virulent Gram-negative meningitis serial sonographic studies showed the development of encephalomalacia. Because clinical neurologic assessment of the infant is limited, a diagnostic imaging method that is sensitive to early structural change and suitable for serial observations is advantageous. Transfontanelle real-time sonographic examination of the brain was found to be a reliable, informative, and relatively inexpensive method of documenting and monitoring complicated bacterial meningitis.