Persistence of tracer in the application site -a potential confounding factor in nerve regeneration studies

Selective reinnervation of peripheral targets after nerve injury might be assessed by injecting a first tracer in a target before nerve injury to label the original neuronal population, and applying a second tracer after the regeneration period to label the regenerated population. However, altered uptake of tracer, fading, and cell death may interfere with the results. Furthermore, if the first tracer injected remains in the target tissue, available for 're-uptake' by misdirected regenerating axons, which originally innervated another region, then the identification of the original population would be confused. With the aim of studying this problem, the sciatic nerve of adult rats was sectioned and sutured. After 3 days, to allow the distal axon to degenerate avoiding immediate retrograde transport, one of the dyes: Fast Blue (FB), Fluoro-Gold (FG) or Diamidino Yellow (DY), was injected into the tibial branch of the sciatic nerve, or in the skin of one of the denervated digits. Rats survived 2-3 months. The results showed labelled dorsal root ganglion (DRG) cells and motoneurones, indicating that late re-uptake of a first tracer occurs. This phenomenon must be considered when the model of sequential labelling is used for studying the accuracy of peripheral reinnervation.

New sample of drosophilids from the Font Groga site, Barcelona (Spain)

A new sample of drosophilids was obtained from Font Groga (Barcelona) on 9th October 2013. Flies were netted over 12 baits containing fermenting bananas placed along a trail from 4 to 7 pm. The number of flies classified according to species and sex is presented in Table 1. The most abundant species is D. subobscura (62.60%). This is expected because the sample was obtained during its autumn peak of expansion. Also interesting is to find again D. suzukii, and in a percentage similar (9.20%) to that obtained in 2012 sample. This species invaded recently many European regions and seems it is well established. We have finally estimated the species diversity using H" (Shannon diversity index) and J (Shannon uniformity index). The values obtained were 0.990 and 0.615, respectively. They are similar to those estimates obtained in the same site by Calabria in autumn 2007 and higher than those of Canals et al. in late autumn 2012.

Building complexity in O2-binding copper complexes : site-selective metalation and intermolecular O2-binding at dicopper and heterometallic complexes derived from an unsymmetric ligand

A novel unsymmetric dinucleating ligand (LN3N4) combining a tridentate and a tetradentate binding sites linked through a m-xylyl spacer was synthesized as ligand scaffold for preparing homo- and dimetallic complexes, where the two metal ions are bound in two different coordination environments. Site-selective binding of different metal ions is demonstrated. LN3N4 is able to discriminate between CuI and a complementary metal (M′ = CuI, ZnII, FeII, CuII, or GaIII) so that pure heterodimetallic complexes with a general formula [CuIM′(LN3N4)]n+ are synthesized. Reaction of the dicopper(I) complex [CuI 2(LN3N4)]2+ with O2 leads to the formation of two different copper-dioxygen (Cu2O2) intermolecular species (O and TP) between two copper atoms located in the same site from different complex molecules. Taking advantage of this feature, reaction of the heterodimetallic complexes [CuM′(LN3N4)]n+ with O2 at low temperature is used as a tool to determine the final position of the CuI center in the system because only one of the two Cu2O2 species is formed

1,2,3,4-Tetrahydrobenzo[h][1,6]naphthyridines as a new family of potent peripheral-to-midgorge-site inhibitors of acetylcholinesterase: synthesis, pharmacological evaluation and mechanistic studies

A series of 1,2,3,4-tetrahydrobenzo[h][1,6]naphthyridines differently substituted at positions 1, 5, and 9 have been designed from the pyrano[3,2-c]quinoline derivative 1, a weak inhibitor of acetylcholinesterase (AChE) with predicted ability to bind to the AChE peripheral anionic site (PAS), at the entrance of the catalytic gorge. Fourteen novel benzonaphthyridines have been synthesized through synthetic sequences involving as the key step a multicomponent Povarov reaction between an aldehyde, an aniline and an enamine or an enamide as the activated alkene. The novel compounds have been tested against Electrophorus electricus AChE (EeAChE), human recombinant AChE (hAChE), and human serum butyrylcholinesterase (hBChE), and their brain penetration has been assessed using the PAMPA-BBB assay. Also, the mechanism of AChE inhibition of the most potent compounds has been thoroughly studied by kinetic studies, a propidium displacement assay, and molecular modelling. We have found that a seemingly small structural change such as a double O → NH bioisosteric replacement from the hit 1 to 16a results in a dramatic increase of EeAChE and hAChE inhibitory activities (>217- and >154-fold, respectively), and in a notable increase in hBChE inhibitory activity (> 11-fold), as well. An optimized binding at the PAS besides additional interactions with AChE midgorge residues seem to account for the high hAChE inhibitory potency of 16a (IC50 = 65 nM), which emerges as an interesting anti-Alzheimer lead compound with potent dual AChE and BChE inhibitory activities.

1,2,3,4-Tetrahydrobenzo[h][1,6]naphthyridines as a new family of potent peripheral-to-midgorge-site inhibitors of acetylcholinesterase: synthesis, pharmacological evaluation and mechanistic studies

A series of 1,2,3,4-tetrahydrobenzo[h][1,6]naphthyridines differently substituted at positions 1, 5, and 9 have been designed from the pyrano[3,2-c]quinoline derivative 1, a weak inhibitor of acetylcholinesterase (AChE) with predicted ability to bind to the AChE peripheral anionic site (PAS), at the entrance of the catalytic gorge. Fourteen novel benzonaphthyridines have been synthesized through synthetic sequences involving as the key step a multicomponent Povarov reaction between an aldehyde, an aniline and an enamine or an enamide as the activated alkene. The novel compounds have been tested against Electrophorus electricus AChE (EeAChE), human recombinant AChE (hAChE), and human serum butyrylcholinesterase (hBChE), and their brain penetration has been assessed using the PAMPA-BBB assay. Also, the mechanism of AChE inhibition of the most potent compounds has been thoroughly studied by kinetic studies, a propidium displacement assay, and molecular modelling. We have found that a seemingly small structural change such as a double O → NH bioisosteric replacement from the hit 1 to 16a results in a dramatic increase of EeAChE and hAChE inhibitory activities (>217- and >154-fold, respectively), and in a notable increase in hBChE inhibitory activity (> 11-fold), as well. An optimized binding at the PAS besides additional interactions with AChE midgorge residues seem to account for the high hAChE inhibitory potency of 16a (IC50 = 65 nM), which emerges as an interesting anti-Alzheimer lead compound with potent dual AChE and BChE inhibitory activities.

1,2,3,4-Tetrahydrobenzo[h][1,6]naphthyridines as a new family of potent peripheral-to-midgorge-site inhibitors of acetylcholinesterase: synthesis, pharmacological evaluation and mechanistic studies

A series of 1,2,3,4-tetrahydrobenzo[h][1,6]naphthyridines differently substituted at positions 1, 5, and 9 have been designed from the pyrano[3,2-c]quinoline derivative 1, a weak inhibitor of acetylcholinesterase (AChE) with predicted ability to bind to the AChE peripheral anionic site (PAS), at the entrance of the catalytic gorge. Fourteen novel benzonaphthyridines have been synthesized through synthetic sequences involving as the key step a multicomponent Povarov reaction between an aldehyde, an aniline and an enamine or an enamide as the activated alkene. The novel compounds have been tested against Electrophorus electricus AChE (EeAChE), human recombinant AChE (hAChE), and human serum butyrylcholinesterase (hBChE), and their brain penetration has been assessed using the PAMPA-BBB assay. Also, the mechanism of AChE inhibition of the most potent compounds has been thoroughly studied by kinetic studies, a propidium displacement assay, and molecular modelling. We have found that a seemingly small structural change such as a double O → NH bioisosteric replacement from the hit 1 to 16a results in a dramatic increase of EeAChE and hAChE inhibitory activities (>217- and >154-fold, respectively), and in a notable increase in hBChE inhibitory activity (> 11-fold), as well. An optimized binding at the PAS besides additional interactions with AChE midgorge residues seem to account for the high hAChE inhibitory potency of 16a (IC50 = 65 nM), which emerges as an interesting anti-Alzheimer lead compound with potent dual AChE and BChE inhibitory activities.