Delivering a missing gene or a functional substitute of a defective gene has the potential to revolutionize current medical care. Of the two gene delivery approaches, viral and synthetic vectors, synthetic cationic vectors possess several practical advantages but suffer from poor transfection efficiency. A new approach to gene delivery using charge-reversal amphiphiles is described. This synthetic vector transforms from a cationic to an anionic amphiphile intracellularly. This amphiphile performs two roles: first, it binds and then releases DNA, and second, as an anionic multicharged amphiphile, it destabilizes lipid bilayers. A charge-reversal amphiphile was synthesized and fully characterized, including the supramolecular complex it forms with DNA. Enhanced gene transfection was observed using these vectors compared to current cationic amphiphiles.

Binary mixtures of fluorocarbon and hydrocarbon nonionic surfactants derived from the tris-(hydroxymethyl)acrylamidomethane (THAM) have been examined by 19 F NMR spectroscopy and UVvisible spectroscopy in the presence of pinacyanol chloride as a probe. Aqueous solutions have been studied as a function of total surfactant concentration over a range of fluorocarbon/hydrocarbon ratios. For molar fractions in fluorinated surfactant lower than 0.7, the variations of both the 19 F chemical shift and of the absorbance show two inflection points as a function of surfactant concentration. This was assigned to two critical micelle concentrations (cmc's). Above the second cmc, two kinds of micelles (fluorocarbon-rich and hydrocarbon-rich) should coexist as a result of the incompatibility between the two types of surfactants. The experimental results cannot be adequately described by current models on demixing micellar systems. An explanation of this behavior is suggested, by taking into account the interactions between the polyhydroxylated headgroups of the surfactants.

SUMMARYAim: To compare the efficacy of different regimens in patients in whom previous Helicobacter pylori eradication therapy has failed. Methods: In this study named StratHegy patients (n ¼ 287) were randomized to receive one of three empirical triple therapy regimens or a strategy based on antibiotic susceptibility. The empirical regimens were omeprazole, 20 mg b.d., plus amoxicillin, 1000 mg b.d., and clarithromycin, 500 mg b.d., for 7 days (OAC 7 ), clarithromycin, 500 mg b.d., for 14 days (OAC 14 ) or metronidazole, 500 mg b.d., for 14 days (OAM 14 ). In the susceptibility-based strategy, patients with clarithromycin-susceptible strains received OAC 14 , whilst the others received OAM 14 . The 13 C-urea breath test was performed before randomization and 4-5 weeks after eradication therapy.Results: In the intention-to-treat analysis, the eradication rates for empirical therapies were as follows: OAC 7 , 47.4% (27/57); OAC 14 , 34.5% (20/58); OAM 14 , 63.2% (36/57); it was 74.3% (84/113) for the susceptibilitybased treatment (P < 0.01 when compared with OAC 7 and OAC 14 ). In patients receiving clarithromycin, the eradication rates were 80% for clarithromycin-susceptible strains and 16% for clarithromycin-resistant strains; in patients receiving OAM 14 , the eradication rates were 81% for metronidazole-susceptible strains and 59% for metronidazole-resistant strains. Conclusions: Eradication rates of approximately 75% can be achieved with second-line triple therapy based on antibiotic susceptibility testing. If susceptibility testing is not available, OAM 14 is an appropriate alternative.

Eradication rates obtained in this study were lower than those expected on the basis of previously reported studies. This study supports the use of a double dose of omeprazole, although the difference between groups was non-significant, but provides no argument in favour of a high dose of clarithromycin.

A series of novel polymerizable hydrocarbon and fluorocarbon cationic surfactants (N-alkoxycarboxymethyl-N-[2-(N ′-alkylacrylamido)ethyl]-N,N-dimethylammonium bromide) potentially useful for the formation of multicompartment polymeric micelles were prepared. Micellization and surface active properties of these surfactants and of their mixtures were determined by electrical conductivity and surface tension measurements. The interaction between the fluorocarbon and the hydrocarbon surfactants in the aqueous micellar state can be described by the regular solution theory with an interaction parameter ) 1.25 indicating the formation of one type of mixed micelles. The solubilization capacity of the pure and of the mixed surfactant systems for pyrene and for a new fluorocarbon azo dye were studied by UV absorption as a function of the surfactant concentration. It was found that the ability to solubilize these hydrophobic compounds depends strongly on the nature of the micellar core (hydrocarbon, fluorocarbon, or mixed), the polarity of the dye, the micellar shape, and the composition of the surfactant mixture. Langmuir 1998, 14, 4765-4775 S0743-7463(98)00245-5 CCC: $15.00

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DNA transfections are widely performed in research laboratories and in vivo gene delivery holds the promise for curing many diseases. The synthetic carriers or vectors for DNA are typically cationic lipids. However, in biology, the recognition of nucleic acids by proteins involves both electrostatic and stacking contributions. As such we have prepared a series of new lipophilic peptide vectors that possess lysine and tryptophan amino acids for evaluation. These lipophilic peptides show minimal cytotoxicity and enhanced in vitro gene transfection activity.The complexation of cationic amphiphiles with DNA or RNA and the resulting supramolecular structures are of interest for the delivery of nucleic acids to cells. As such, a means to correct a defective gene, introduce a new gene, or knock-down a gene is provided for a specific in vitro or in vivo application (1-7). This complexation between cationic amphiphiles and nucleic acids is governed by electrostatic interactions between the positively charged amphiphiles and the negatively charged phosphate backbone of the nucleic acid and the hydrophobic chainchain packing forces between the individual assembled amphiphiles. In biology, the recognition of nucleic acids by proteins involves more than electrostatic interactions (8-10). Examination of these protein nucleic acid recognition motifs typically reveals structures rich in basic and aromatic amino acids that provide important electrostatic and stacking contributions to binding. With this inspiration in mind, we are designing peptide-based amphiphiles for gene delivery. Herein we describe a series of lipophilic peptides including the synthesis, physiochemical properties, cytotoxicity, and in vitro gene transfection activity.To mimic structural characteristics present in nucleic acid binding proteins, we selected the tripeptide Lys-Trp-Lys, KWK, to be the headgroup for the amphiphile because it possesses cationic charges and an aromatic side chain and is relatively small in size. Moreover, this peptide is known to bind DNA with a binding constant on the order of 10 4 M and is a model peptide used to study protein-nucleic acid interactions, and lysine and tryptophan provide important interactions in a number of structurally characterized DNA binding domains of proteins (11)(12)(13)(14). In addition, lysine-based small molecule amphiphiles and macromolecules (e.g., polylysine) are being explored and used for gene transfection (15)(16)(17)(18)(19)(20)(21)(22)(23)(24). In order to perform a systematic study to identify the key molecular components responsible for transfection © 2008 American Chemical Society * Correspondence should be addressed to M.W.G.; author E-mail: mgrin@bu.edu. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript activity with these new lipophilic peptides, we prepared a series of amphiphiles where the headgroup (charge, aliphatic content, aromatic content) and fatty acid chain length (C12:0, C14:0, C16:0, and C18:0) were varied. As shown in Figure ...

Escherichia coil BM2195 is highly resistant to erythromycin by inactivation of the antibiotic. We have determined the structure of the modified antibiotic by physico-chemical techniques including mass spectrometry, infrared spectrophotometry, 13C nuclear magnetic resonance, and circular dichroism.The results obtained indicate that E. coli BM2195 resists erythromycin by the production of an erythromycin esterase which hydrolyzes the lactone ring of the antibiotic.Escherichia coli, like most Gram-negative bacteria, is resistant to "low levels" of macrolides (minimal inhibitory concentrations (MICs) <250 1+g/m1) . We recently described an E. coil strain, BM2195, resistant to high-levels (MIC > 2 mg/ml) of erythromycin and demonstrated that this new resistant phenotype was due to the constitutive synthesis of a plasmid-mediated erythromycin-modifying enzyme1).The genetic information located on the plasmid was transferred to E. coil BM694, and, using this strain, the modified antibiotic was isolated and its structure was determined; the resistance involves the production of an erythromycin esterase which hydrolyzes the lactone ring of the antibiotic. Materials and MethodsBacteria] Strains and Plasmids E. coil BM2506 which is highly resistant to erythromycin (MIC > 1 mg/ml) and does not inactivate the antibiotic was a clinical isolate, identified and kindly provided by A. ANDREMONT, Institut GustaveRoussy, Villejuif. E. coli BM694, prototroph, gyrA2) and E. coli BM694/pAT63 were from our laboratory collection. Hybrid plasmid pAT63 consists of pBR322 (Tra-, Mob-, ApR, TcR) with a 1,660bp Sau3a insert of plasmid pIPI 100 DNA encoding the erythromycin esterase3). MediaBrain-heart infusion broth and agar (Difco) were used. Disc agar diffusion susceptibility tests were done on Mueller-Hinton agar. All incubations were at 37°C. Antibiotic Erythromycin base was provided by Roussel-Uclaf. Inactivation of Erythromycin by Resting CellsCells from 1 liter of an exponential broth culture of E. coil BM694/pAT63, at approximately 3 x 10° bacteria/ml, were harvested, washed once in 0.1 M phosphate buffer (pH 7.0 or 8.0), resuspended in 1 liter of the same buffer containing I mg/mi of erythromycin, and incubated for 3 hours at 37°C. The pH of this suspension, which remained constant, was monitored and inactivation of erythromycin was