Creutzfeldt-Jakob disease

Adaptation of the protein misfolding cyclic amplification (PMCA) technique for the screening of anti-prion compounds

Prion diseases result from the misfolding of the physiological prion protein (PrPC) to a pathogenic conformation (PrPSc). Compelling evidence indicates that prevention and/or reduction of PrPSc replication are promising therapeutic strategies against prion diseases. However, the existence of different PrPSc conformations (or strains) associated with disease represents a major problem when identifying anti-prion compounds. Efforts to identify strain-specific anti-prion molecules are limited by the lack of biologically relevant high-throughput screening platforms to interrogate compound libraries. Here, we describe adaptations to the protein misfolding cyclic amplification (PMCA) technology (able to faithfully replicate PrPSc strains) that increase its throughput to facilitate the screening of anti-prion molecules. The optimized PMCA platform includes a reduction in sample and reagents, as well as incubation/sonication cycles required to efficiently replicate and detect rodent-adapted and cervid PrPSc strains. The visualization of PMCA products was performed via dot blots, a method that contributed to reduced processing times. These technical changes allowed us to evaluate small molecules with previously reported anti-prion activity. This proof-of-principle screening was evaluated for six rodent-adapted prion strains. Our data show that these compounds targeted either none, all or some PrPSc strains at variable concentrations, demonstrating that this PMCA system is suitable to test compound libraries for putative anti-prion molecules targeting specific PrPSc strains. Further analyses of a small compound library against deer prions demonstrate the potential of this new PMCA format to identify strain-specific anti-prion molecules. The data presented here demonstrate the use of the PMCA technique in the selection of prion strain-specific anti-prion compounds.

Polybioside, a neuroactive compound from the venom of the social wasp Polybia paulista

Polybioside (1) was isolated from the venom of the social wasp Polybia paulista, and its structure was assigned as 3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl 3-(1H-imidazol-4-yl)propanimidate by NMR and MS protocols. The application of polybioside in rat brain, followed by the detection of c-Fos protein expression in some brain regions, indicated the compound is neuroactive in a number of brain areas. Polybioside causes convulsions in rats, even when peripherally applied.

Parkinsonism after a wasp sting

A 49-year-old man had mild parkinsonism after being stung by a wasp, a member of the Hymenoptera order. His clinical course was stable for 6 months after which his condition rapidly progressed to a severe akinetic-rigid syndrome with evidence, on a magnetic resonance imaging brain scan, of marked destruction of the basal ganglia. The symptoms did not respond to standard antiparkinsonian medications. Repeated courses of plasmapheresis followed by monthly intravenous infusions of immunoglobulin and long-term administration of azathioprine halted and appeared to partially reverse his deterioration. The literature on the neurologic, particularly the extrapyramidal, manifestations of stings by insects of the Hymenoptera order is reviewed and the possible pathophysiological mechanisms of injury are discussed. Hymenoptera stings should be included in the differential diagnosis of acute and chronic extrapyramidal syndromes.