Discovery of a novel class of biphenyl pyrazole sodium channel blockers for treatment of neuropathic pain

A series of novel biphenyl pyrazole dicarboxamides were identified as potential sodium channel blockers for treatment of neuropathic pain. Compound 20 had outstanding efficacy in the Chung rat spinal nerve ligation (SNL) model of neuropathic pain.     

Effect of delayed supplementation of fetal calf serum to culture medium on bovine embryo development in vitro and following transfer

Supplementation of synthetic oviduct fluid (SOF) medium plus amino acids and bovine serum albumin (BSA) with either fetal calf serum (FCS) or charcoal-treated FCS (CT-FCS) from Day 5 of development was investigated to determine if either in vitro or post-transfer development was altered. Development to the compact morula stage or beyond was similar for all 3 treatments. However, blastocyst development at Day 7 was accelerated when serum was added to the medium (21.6, 40.1 and 39.4% blastocysts from cleaved embryos for BSA, FCS and CT-FCS, respectively; P < 0.01), but cell number of the resulting embryos was unaffected. Furthermore, addition of CT-FCS decreased the between replicate variation in embryo development and produced more Grade 1 and 2 quality embryos (25.8%) than BSA supplementation (18.1%; P < 0.05). The transfer of Grade 1 and 2 embryos at Day 7 following culture resulted in similar pregnancy and embryo survival rates for the 3 treatments, with a tendency for lower embryo survival of embryos cultured in FCS (embryo survival at Day 50 = 37.7% vs 53.3% and 57.6% for FCS, BSA and CT-FCS, respectively; P = 0.1). Significant fetal loss from Day 50 to term occurred within all 3 treatments. There were no birth weight differences for calves amongst the 3 culture treatments; however, one of the sires produced calves that were significantly heavier than expected, suggesting a possible sire-by-embryo interaction. These results demonstrate that addition of FCS may promote blastocyst development; however, there was also a tendency for lower embryo survival. Thus charcoal treatment of FCS is recommended, because it decreases variability in embryo development between runs and results in embryo survival rates to term similar to that BSA-supplemented media.     

X-ray Crystal Structure and Specificity of the Plasmodium falciparum Malaria Aminopeptidase PfM18AAP

The malarial aminopeptidases have emerged as promising new drug targets for the development of novel antimalarial drugs. The M18AAP of Plasmodium falciparum malaria is a metallo-aminopeptidase that we show demonstrates a highly restricted specificity for peptides with an N-terminal Glu or Asp residue. Thus, the enzyme may function alongside other aminopeptidases in effecting the complete degradation or turnover of proteins, such as host hemoglobin, which provides a free amino acid pool for the growing parasite. Inhibition of PfM18AAP's function using antisense RNA is detrimental to the intra-erythrocytic malaria parasite and, hence, it has been proposed as a potential novel drug target. We report the X-ray crystal structure of the PfM18AAP aminopeptidase and reveal its complex dodecameric assembly arranged via dimer and trimer units that interact to form a large tetrahedron shape that completely encloses the 12 active sites within a central cavity. The four entry points to the catalytic lumen are each guarded by 12 large flexible loops that could control substrate entry into the catalytic sites. PfM18AAP thus resembles a proteasomal-like machine with multiple active sites able to degrade peptide substrates that enter the central lumen. The Plasmodium enzyme shows significant structural differences around the active site when compared to recently determined structures of its mammalian and human homologs, which provides a platform from which a rational approach to inhibitor design of new malaria-specific drugs can begin.