Differential expression of matrix metalloproteinases and interleukin-8 during regeneration of human airway epithelium in vivo

In many airway diseases, the airway epithelium is severely damaged and has to regenerate rapidly to restore its function. The regeneration process involves chronological steps of epithelial cell migration, proliferation, stratification, and differentiation. The present study has used an in vivo humanized airway xenograft model in nude mice that mimics the regeneration dynamics of human airway epithelium after severe injury, and human-specific molecular tools, to study the expression profiles of epithelial matrix metalloproteinases (MMPs)-7 and -9, of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), and of the pro-inflammatory cytokine interleukin-8 (IL-8) during the different steps of human airway epithelium regeneration. It was found that during the cell migration and proliferation steps, airway epithelial cells expressed IL-8 at a high level, whereas airway epithelial pseudo-stratification and surface airway epithelial differentiation were associated with increased expression of MMPs and a progressive decrease in IL-8. Interestingly, immunohistochemical analysis revealed exclusive expression of MMPs at the apical part of the well-differentiated regenerated airway epithelium, and incubation of the regenerating epithelial cells with MMP inhibitors led to abnormal epithelial differentiation. These data provide new insight into the temporal expression of MMPs and IL-8 during the regeneration of airway epithelium and demonstrate the involvement of these factors during the different steps that lead to restoration of a well-differentiated and functional airway epithelium.     

Lopinavir/ritonavir combination and total/HDL cholesterol ratio

OBJECTIVES: To describe the evolution of the lipidic profile among LPV/r treated patients in a 'real life' situation. METHODS: Lipids measurements at LPV/r initiation time and every 3 months, and pharmacological measurements at M3 and M6 were collected retrospectively in 142 patients attending our clinic. Dyslipidaemia was defined as total cholesterol > or =6.2 mmol/l, HDL-cholesterol > or =1 mmol/l, total/HDL-cholesterol ratio > or =6.5 and triglycerides > or =2.3 mmol/l. RESULTS: Eighty-nine percent of patients had previously received a regimen with protease inhibitors, 4% were treatment naive. At baseline, 17% of patients had high total cholesterol, 49% high triglycerides, 63% low HDL-cholesterol, 25% a high total/HDL-cholesterol ratio. At M12, the mean HDL-cholesterol increase per patient was 21%. Lipids levels significantly increased over the study period, as early as the 3rd month (6th month for ratio) and continuously until the 12th month. Among the patients with available LPV/r plasma determinations at M3, a higher lopinavir residual concentration was observed in those with high triglycerides (6.78 vs 3.02 mg/l, p = 0.05) as, at M6, in those with an elevated ratio (9.19 vs 0.96 mg/l, p = 0.02). CONCLUSIONS: Those results suggest that LPV/r may induce a significant rise in the total/HDL-cholesterol ratio, despite an increase in HDL-cholesterol levels. The association between triglycerides and total/HDL-cholesterol ratio elevated levels and high residual concentrations of lopinavir may also argue for systematic drug monitoring.     

Design and synthesis of specific probes for human 5-HT4 receptor dimerization studies

Recently, human 5-HT4 receptors have been demonstrated to form constitutive dimers in living cells. To evaluate the role of dimerization on the 5-HT4 receptor function, we investigated the conception and the synthesis of bivalent molecules able to influence the dimerization process. Their conception is based on a model of the 5-HT4 receptor dimer derived from protein/protein docking experiments. These bivalent ligands are constituted by two ML10302 units, a specific 5-HT4 ligand, linked through a spacer of different sizes and natures. These synthesized bivalent ligands were evaluated in binding assays and cyclic AMP production on the 5-HT4(e/g) receptor isoform stably transfected in C6 glial cells. Our data showed that bivalent ligands conserved a similar affinity compared to the basal ML10302 unit. Nevertheless, according to the nature and the size of the spacer, the pharmacological profile of ML10302 is more or less conserved. In view of the interest of bivalent ligands for investigating the GPCR dimerization process, these 5-HT4 specific bivalent ligands constitute valuable pharmacological tools for the study of 5-HT4 receptor dimerization.     

Quantification and pharmacological characterization of dialysate levels of noradrenaline in the striatum of freely-moving rats: release from adrenergic terminals and modulation by alpha2-autoreceptors

Information concerning striatal levels of noradrenaline (NA) remains inconsistent. Here we have addressed this issue using a sensitive method of HPLC coupled to amperometric detection. The NA reuptake-inhibitor, reboxetine, selectively elevated levels of NA versus dopamine (DA), and NA levels were also selectively elevated by the alpha2-adrenoceptor (AR) antagonist, atipamezole. The actions of atipamezole were mimicked by the preferential alpha2A-AR antagonist, BRL44408, while JO-1 and prazosin, preferential antagonists at alpha2C-ARs, caused less marked elevations in NA levels. In contrast to antagonists, the alpha2-AR agonist, S18616, decreased NA levels and likewise suppressed those of DA. Unilateral lesions of the substantia nigra with 6-hydroxydopamine depleted DA levels without affecting those of NA. Further, the D3/D2 receptor agonist, quinelorane, decreased levels of DA without modifying those of NA. However, the D3/D2 receptor antagonists, haloperidol and raclopride, and the DA reuptake-inhibitor, GBR12935, elevated levels of both DA and NA. Levels of 5-HT (but not of NA or DA) were increased only by the 5-HT reuptake-inhibitor, citalopram. They were decreased by S18616 and prazosin, reflecting the inhibitory and excitatory influence of alpha2- and alpha1-ARs, respectively, upon serotonergic pathways. In conclusion, NA in the striatum is derived from adrenergic terminals. Its release is subject to tonic, inhibitory control by alpha2-ARs, possibly involving both alpha2A- and alpha2C-AR subtypes, though their respective contribution requires clarification. A role of dopaminergic terminals in the reuptake of NA likely explains the elevation in its levels elicited by DA reuptake-inhibitors and D3/D2 receptor antagonists.     

Gait-dependent motor memory facilitation in covert movement execution

In the current study, we examined whether sensorimotor information stored in short-term memory may influence the temporal features between overt and covert execution of human locomotor movements and, furthermore, to examine to what extent such influence may depend on the ongoing gait activity. The subjects (n=20) who participated in the experiment were separated in two groups and instructed to walk (overt execution) or imagine walking (covert execution) along three locomotor paths: horizontal, uphill and downhill. The subjects of the first group, labeled in block, performed all the covert trials before executing the corresponding overt trials, while the subjects of the second group, labeled in serial, alternated between overt and covert movements. The overt and covert durations were recorded by means of an electronic stopwatch. We found high temporal similarities between overt and covert execution for both groups and for all the locomotor paths. Nevertheless, the execution of imagined movements was more variable compared to their actual counterparts. In addition, timing variability of covert movements was smaller for the group in serial compared to the group in block. This decrease in timing variability was larger for the horizontal walking compared to uphill or downhill locomotion. Furthermore, linear regression analysis performed on the data of the group in serial showed close temporal relationships between each successive overt and covert execution. These relationships were stronger when walking along the horizontal vs. sloped paths. Therefore, our results on timing variability provide evidence for gait-dependent motor memory facilitation in covert movement execution. We propose that gait-dependent contribution of sensory feedback information to movement regulation may account for these findings.