Compounds acting at the endocannabinoid and/or endovanilloid systems reduce hyperkinesia in a rat model of Huntington's disease

We have recently reported that the administration of AM404, an inhibitor of the endocannabinoid re-uptake process, which also has affinity for the vanilloid VR1 receptors, is able to reduce hyperkinesia, and causes recovery from neurochemical deficits, in a rat model of Huntington's disease (HD) generated by bilateral intrastriatal injections of 3-nitropropionic acid (3NP). In the present study, we wanted to explore the mechanism(s) by which AM404 produces its antihyperkinetic effect in 3NP-lesioned rats by employing several experimental approaches. First, we tried to block the effects of AM404 with selective antagonists for the CB1 or VR1 receptors, i.e. SR141716A and capsazepine, respectively. We found that the reduction caused by AM404 of the increased ambulation exhibited by 3NP-lesioned rats in the open-field test was reversed when the animals had been pre-treated with capsazepine but not with SR141716A, thus suggesting a major role of VR1 receptors in the antihyperkinetic effects of AM404. However, despite the lack of behavioral effects of the CB1 receptor antagonist, the pretreatment with this compound abolished the recovery of neurochemical [gamma-aminobutyric acid (GABA) and dopamine] deficits in the caudate- putamen caused by AM404, as also did capsazepine. In a second group of studies, we wanted to explore the potential antihyperkinetic effects of various compounds which, compared to AM404, exhibit more selectivity for either the endovanilloid or the endocannabinoid systems. First, we tested VDM11 or AM374, two selective inhibitors or the endocannabinoid re-uptake or hydrolysis, respectively. Both compounds were mostly unable to reduce hyperkinesia in 3NP-lesioned rats, although VDM11 produced a certain motor depression, and AM374 exhibited a trend to stimulate ambulation, in control rats. We also tested the effects of selective direct agonists for VR1 (capsaicin) or CB1 (CP55,940) receptors. Capsaicin exhibited a strong antihyperkinetic activity and, moreover, was able to attenuate the reductions in dopamine and GABA transmission provoked by the 3NP lesion, whereas CP55,940 had also antihyperkinetic activity but was unable to cause recovery of either dopamine or GABA deficits in the basal ganglia. In summary, our data indicate a major role for VR1 receptors, as compared to CB1 receptors, in the antihyperkinetic effects and the recovery of neurochemical deficits caused in 3NP-lesioned rats by compounds that activate both CB1 and VR1 receptors, either directly or via manipulation of the levels of endogenous agonists.     

(-)Epigallocatechin-3-gallate inhibits gelatinase activity of some bacterial isolates from ocular infection,and limits their invasion through gelatine

The objective of this paper is to assess the gelatinase production by some ocular pathogenic bacterial strains, and evaluate the ability of (-)epigallocatechin-3-gallate (EGCg) to inhibit this gelatinase activity and thus limit bacterial invasion. The effect of EGCg on bacterial gelatinase activity was tested by classic zymography methods, while its effect on bacterial invasion was evaluated through the ability of growing bacteria to liquefy and thus penetrate a semisolid gelatine substrate. It was found that EGCg inhibits bacterial gelatinases with an IC(50) of about 0.2 mM, and limits invasion of gelatinase-positive bacteria at concentrations above 2 mM. These results show for the first time that EGCg, as well as having direct antibacterial activity, can also inhibit bacterial gelatinases, thus limiting their invasion on gelatine. Possible use of EGCg is thus suggested as an adjuvant in antibacterial chemotherapy.     

The atypical lipase B from Candida antarctica is better adapted for organic media than the typical lipase from Thermomyces lanuginosa

Candida antarctica lipase B (CALB) and Thermomyces lanuginosa lipase (TLL) were evaluated as catalysts in different reaction media using hydrolysis of tributyrin as model reaction. In o/w emulsions, the enzymes were used in the free form and for use in monophasic organic media, the lipases were adsorbed on porous polypropylene (Accurel EP-100). In monophasic organic media, the highest specific activity of both lipases was obtained in pure tributyrin at a water activity of >0.5 and at an enzyme loading of 10 mg/g support. With tributyrin emulsified in water, the specific activities were 2780 micromol min(-1) mg(-1) for TLL and 535 micromol min(-1) mg(-1) for CALB. Under optimal conditions in pure tributyrin, CALB expressed 49% of the activity in emulsion (264 micromol min(-1) mg(-1)) while TLL expressed only 9.2% (256 micromol min(-1) mg(-1)) of its activity in emulsion. This large decrease is probably due to the structure of TLL, which is a typical lipase with a large lid domain. Conversion between open and closed conformers of TLL involves large internal movements and catalysis probably requires more protein mobility in TLL than in CALB, which does not have a typical lid region. Furthermore, TLL lost more activity than CALB when the water activity was reduced below 0.5, which could be due to further reduction in protein mobility.     

In vitro selection of high affinity HspR-binding sites within the genome of Helicobacter pylori

The major chaperone genes of Helicobacter pylori are negatively regulated by HspR, a homologue of the repressor of the dnaK operon of Streptomyces coelicolor. Using an in vitro selection and amplification approach we identified two new chromosomal binding sites of the HspR protein. Both binding sites were characterized by footprinting analysis with purified HspR protein. Intriguingly, these HspR binding sites are located at the 3prime prime or minute ends of two genes coding for predicted proteins with functions unrelated to those of chaperones. This suggests that H. pylori HspR may regulate the expression of genes encoding proteins with diverse functions. Nucleotide sequence alignment of HspR-binding sites highlights conserved nucleotides extending outside the previously proposed consensus binding sequence with structural features predicting geometry of HspR binding as an oligomer.     

A carboxylesterase from the hyperthermophilic archaeon Sulfolobus solfataricus: cloning of the gene, characterization of the protein

A genomic library of the hyperthermophilic archaeon Sulfolobus solfataricus strain MT4 was constructed in Escherichia coli using a cloning vector not designed for heterologous gene expression. One positive clone exhibiting acquired thermophilic acetylesterase activity was directly detected by an in situ plate assay using a colony staining procedure with the chromogenic substrate beta-naphthyl acetate. The plasmid isolated from the clone contained a 3.3 kb genomic fragment from S. solfataricus and a full-length esterase coding sequence could be identified. Expression of the active thermostable esterase in E. coli was independent of isopropyl-beta-D-thiogalactopyranoside and of the kind of vector, suggesting that the archaeal esterase gene was controlled by fortuitous bacterial-like sequences present in its own 5' flanking region, not by the bacterial lac promoter or other serendipitous vector-located sequences. The protein, partially purified by thermoprecipitation of the host proteins at high temperature and gel exclusion chromatography, showed a homo-tetrameric structure with a subunit of molecular mass of 32 kDa which was in perfect agreement with that deduced from the cloned gene. The same protein was revealed in S. solfataricus cell extracts, thus demonstrating its functional occurrence in vivo under the cell culture conditions tested. The recombinant enzyme exhibited high thermal activity and thermostability with optimal activity between pH 6.5 and 7.0. The hydrolysis of p-nitrophenyl esters of fatty acids (from C(2) to C(8)) allowed the enzyme to be classified as a short length acyl esterase.     

Structural and physicochemical characterization of the inclusion complexes of cyclomaltooligosaccharides (cyclodextrins) with melatonin

The stoichiometry, geometry, stability, and solubility of the inclusion complexes of melatonin (MLT) with native cyclomaltooligosaccharides (alpha-, beta- or gamma-cyclodextrins, CDs) are determined experimentally by high-resolution NMR spectroscopy, calorimetric and solubility measurements, and mass spectrometry. The observed differences are discussed in terms of molecular recognition expression of the host-guest (h-g) interactions within the hydrophobic CDs cavities of different size. The 1:1 h-g stoichiometry in water solution prevails at low CD concentrations; the trend to form higher order associations is observed at increasing CD concentrations. The stability order beta-CD>gamma-CD>alpha-CD for the complexes in water solution and beta-CD>alpha-CD>gamma-CD for the protonated or alkali-cationated complexes in the gas phase are rationalized on the grounds of the structural data from NMR spectroscopy and of the thermodynamic parameters from calorimetric measurements.