Targeting neonatal ischemic brain injury with a pentapeptide-based irreversible caspase inhibitor

Brain protection of the newborn remains a challenging priority and represents a totally unmet medical need. Pharmacological inhibition of caspases appears as a promising strategy for neuroprotection. In a translational perspective, we have developed a pentapeptide-based group II caspase inhibitor, TRP601/ORPHA133563, which reaches the brain, and inhibits caspases activation, mitochondrial release of cytochrome c, and apoptosis in vivo. Single administration of TRP601 protects newborn rodent brain against excitotoxicity, hypoxia–ischemia, and perinatal arterial stroke with a 6-h therapeutic time window, and has no adverse effects on physiological parameters. Safety pharmacology investigations, and toxicology studies in rodent and canine neonates, suggest that TRP601 is a lead compound for further drug development to treat ischemic brain damage in human newborns.     

Immunologic mimicry by a monoclonal antibody of the tricyclic anti-depressants' binding site on muscarinic acetylcholine receptors

Inhibition constants of tricyclic anti-depressants and related drugs determined for a monoclonal anti-nortriptyline antibody were close to those previously calculated with the same compounds for the brain acetylcholine muscarinic receptor. A highly significant correlation was found between these two series of inhibition constants when no correlation existed between the inhibition constants for the antibody and those for other receptors. This suggests that the binding site for tricyclic anti-depressants on the antibody mimics the binding site for these ligands on muscarinic receptors. Although nortriptyline reveals a noncompetitive inhibition of N-methyl-scopolamine binding to muscarinic receptors, muscarinic ligands display weak or no binding to the antibody. These findings indicate that the binding site for tricyclic anti-depressants on the receptor is distinct from that for the muscarinic ligands.     

Intrahemispheric dysfunction in primary motor cortex without corpus callosum: a transcranial magnetic stimulation study

Background  

The two human cerebral hemispheres are continuously interacting, through excitatory and inhibitory influences and one critical structure subserving this interhemispheric balance is the corpus callosum. Interhemispheric neurophysiological abnormalities and intrahemispheric behavioral impairments have been reported in individuals lacking the corpus callosum. The aim of this study was to examine intrahemispheric neurophysiological function in primary motor cortex devoid of callosal projections.     

Structural analysis of the epitope recognized by a monoclonal antibody directed against tricyclic antidepressants

After somatic cell fusion between splenocytes of immunized BALB/c mice and NS-1 myeloma cells, a clone was obtained that secreted an anti-nortriptyline antibody of the IgG1 kappa isotype. The association constant of this antibody for pharmacologically active tricyclic antidepressant drugs ranged from 0.6 X 10(7) to 3 X 10(7) M-1. From thermodynamic and binding studies as well as tridimensional structures of tested compounds, the epitope recognized by the monoclonal antibody appeared to include both a hydrophobic tricycle in which the two phenyl rings form an angle of 120 to 130 degrees, and a side chain in which the amino group is separated from the two lateral rings of the tricyclic structure by a distance of approximately 5.9 A and 7.5 A, respectively. This conformation seems to be the one interacting with muscarinic acetylcholine brain receptors.     

Internalin must be on the bacterial surface to mediate entry of Listeria monocytogenes into epithelial cells

Entry of Listeria monocytogenes into cultured epithelial cells requires production of internalin, a protein with features characteristic of some Gram-positive bacterial surface proteins, in particular an LPXTG motif preceding a hydrophobic sequence and a few basic residues at its C-terminal end. By immunofluorescence and immunogold labelling, we show that in wild-type L. monocytogenes, internalin is present on the cell surface and has a polarized distribution similar to that of ActA, another surface protein of L. monocytogenes involved in actin assembly. Through a genetic analysis, we establish that the C-terminal region of internalin is necessary for cell-surface association, and that although internalin is partially released in the culture medium, its location on the bacterial surface is required to promote entry. Finally, using a‘domain-swapping’strategy - replacement of the cell wall anchor of InIA by the membrane anchor of ActA - we show that the reduced ability to adhere and enter cells of strains expressing InIA-ActA correlates with a lower amount of surface-exposed internalin. Taken together, these results suggest that internalin exposed on the bacterial surface mediates direct contact between the bacterium and the host cell.