A retro-inverso cell-penetrating peptide for siRNA delivery.

BACKGROUND: Small interfering RNAs (siRNAs) are powerful tools to control gene expression. However, due to their poor cellular permeability and stability, their therapeutic development requires a specific delivery system. Among them, cell-penetrating peptides (CPP) have been shown to transfer efficiently siRNA inside the cells. Recently we developed amphipathic peptides able to self-assemble with siRNAs as peptide-based nanoparticles and to transfect them into cells. However, despite the great potential of these drug delivery systems, most of them display a low resistance to proteases. RESULTS: Here, we report the development and characterization of a new CPP named RICK corresponding to the retro-inverso form of the CADY-K peptide. We show that RICK conserves the main biophysical features of its L-parental homologue and keeps the ability to associate with siRNA in stable peptide-based nanoparticles. Moreover the RICK:siRNA self-assembly prevents siRNA degradation and induces inhibition of gene expression. CONCLUSIONS: This new approach consists in a promising strategy for future in vivo application, especially for targeted anticancer treatment (e.g. knock-down of cell cycle proteins). Graphical abstract RICK-based nanoparticles: RICK peptides and siRNA self-assemble in peptide-based nanoparticles to penetrate into the cells and to induce target protein knock-down.

Methyl Potassium Siliconate and Siloxane Inhibit the Formation of Multispecies Biofilms on Ceramic Roof Tiles: Efficiency and Comparison of Two Common Water Repellents.

Ceramic roof tiles are widespread marketed building materials, rapidly colonized by microorganisms that form multispecies biofilms on their surface and play crucial roles in biodeterioration processes. Coating tiles with water repellents is a pervasive industrial strategy employed to prevent liquid water penetration and slow biodeterioration. Very few studies have examined the links between the characteristics of water-repellent coatings and biofilm colonization patterns. Our work aims to compare the effects of coating tiles with two common water repellents (siliconate and siloxane) on the growth of colonizing microbes. We combined in situ exposure of tiles for over six years and macroscopic and microscopic observations with in vitro biotests, relying on the use of algal and fungal models. Our data showed that (1) tiles coated with water repellents were macroscopically less colonized by lichens (2) a significant fungal biofilm development at the microscopic scale (3) water repellents had very contrasting effects on our model strains. These data reinforce the great interest for industry to conduct more studies linking the nature of the water repellents with the composition of colonizing multispecies biofilms. The long-term objective is to improve the available water repellents and better adapt their selection to the nature of microbial colonization.

Multiscale characterization of the hierarchical structure of Dynastes hercules elytra.

Beetle elytra are thickened forewings, they are lightweight and tough to protect the hindwings without hindering flight capacities. Dynastes hercules elytra are known for their hygrochromic properties. However, the whole structure of the elytron remains to be characterized. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and to our knowledge for the first time X-Ray tomography were undertaken on adult male Dynastes hercules to characterize their multi-scale structure. Trabeculae present a periodic arrangement over a short distance. Two inferred models describe the heights of plies in endocuticles of dorsal and ventral cuticles. We hypothesize that this study could provide inspiration for biomimetic materials.

PEGylation rate influences peptide-based nanoparticles mediated siRNA delivery in vitro and in vivo.

Small interfering RNAs (siRNAs) present a strong therapeutic potential because of their ability to inhibit the expression of any desired protein. Recently, we developed the retro-inverso amphipathic RICK peptide as novel non-covalent siRNA carrier. This peptide is able to form nanoparticles (NPs) by self-assembling with the siRNA resulting in the fully siRNA protection based on its protease resistant peptide sequence. With regard to an in vivo application, we investigated here the influence of the polyethylene glycol (PEG) grafting to RICK NPs on their in vitro and in vivo siRNA delivery properties. A detailed structural study shows that PEGylation did not alter the NP formation (only decrease in zeta potential) regardless of the used PEGylation rates. Compared to the native RICK:siRNA NPs, low PEGylation rates (≤20%) of the NPs did not influence their cellular internalization capacity as well as their knock-down specificity (over-expressed or endogenous system) in vitro. Because the behavior of PEGylated NPs could differ in their in vivo application, we analyzed the repartition of fluorescent labeled NPs injected at the one-cell stage in zebrafish embryos as well as their pharmacokinetic (PK) profile after administration to mice. After an intra-cardiac injection of the PEGylated NPs, we could clearly determine that 20% PEG-RICK NPs reduce significantly liver and kidney accumulation. NPs with 20% PEGylation constitutes a modular, easy-to-handle drug delivery system which could be adapted to other types of functional moieties to develop safe and biocompatible delivery systems for the clinical application of RNAi-based cancer therapeutics.

[Value of urinary microsatellite analysis in the diagnosis of renal cancer]. / Intérêt de l'analyse des microsatellites urinaires dans le diagnostic du cancer du rein.

OBJECTIVE: To detect the presence of tumour DNA in urine of patients with renal cancer based on microsatellite analysis. MATERIAL AND METHOD: Blinded, comparative, experimental study conducted between July 1996 and December 2003. Preoperative urine and blood samples were collected from 69 patients with renal cancer (pT1 to pT4). The control population comprised 35 patients with a benign urological disease. Loss of heterozygosity (LOH) and allele amplification were investigated by analysing allele imbalances between urinary DNA and blood lymphocyte DNA. Twenty-six loci were analysed, including 23 microsatellites. We studied the sensitivity and specificity of this analysis as a function of stage, grade and invasion of renal cavities by the tumour. RESULTS: The sensitivity of the test was 61% for pT1a and the global sensitivity was 62.3%. A significant difference was observed in favour of low nuclear grades (p < 0.05). More than 80% of tumours detected were identified by 4 microsatellites. The specificity was 83%. Renal cavities were invaded by the tumour in 38% of cases. No correlation was observed between invasion of renal cavities and the result of the test. CONCLUSION: The results are encouraging, particularly for small tumours and justify development of clinical applications.

[Treatment of inferior caliceal stones by flexible ureteroscopy]. / Traitement des calculs caliciels inférieurs par urétéroscopie souple.

OBJECTIVE: Evaluation of the treatment of inferior caliceal stones by flexible ureterorenoscopy and Holinium-YAG laser on a series of 69 operations. MATERIAL AND METHOD: Between April 1998 and December 2003, 69 flexible ureteroscopies were performed for 55 stones in 49 patients. The mean age of the patients was 51.6 years (range: 18-78). The mean stone diameter was 12.8 mm (range: 5-3 1). 46% of stones had been pretreated by ESWL, PCNL or surgery. Endocorporeal lithotripsy was performed by Holmium-YAG laser in 45 cases, Lithoclast in 5 cases and en bloc extraction in 3 cases. Technical features, efficacy and morbidity were studied. The results were classified into fragment-free (FS), residual fragments (RF) < or = 4 mm, RF > 4 mm and failures. The results were evaluated on D0-D1 and at 3 months on a plain abdominal x-ray and ultrasound. RESULTS: The mean operating time was 61 minutes (range: 25-120). Nine stones required several procedures. 20% of stones were cystine stones. A ureteric stent was placed in 67 cases. The mean length of stay was 2.5 days (D0-D8). At 3 months, after one or several ureteroscopies, the results were: 22% FS, 40% RF < or = 4 mm, 13% RF > 4 mm and 25% failures. One half of failures occurred during the first 14 ureteroscopy procedures. There were 13 minor complications and no major complications. CONCLUSIONS: The results of flexible ureteroscopy in the treatment of inferior caliceal stones are encouraging, especially with standardization of the technique. It appears to be a good compromise between ESWL and PCNL, particularly for stones between 10 and 20 mm, cystine stones and after failure of reference techniques.