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Cationic peptides containing Lys and Arg residues interact with DNA via charge-charge interactions and are known to play an important role in DNA charge neutralization and condensation processes. In this paper, we describe investigations of the interaction of the cationic adenovirus core complex peptide mu with a dodecameric ODN (12 bp) and pDNA (7528 bp) using a combination of fluorescence spectroscopy, circular dichroism spectroscopy, isothermal titration calorimetry, and photon correlation spectroscopy. Comparisons are made with protamine, a cationic peptide well-known for DNA charge neutralization and condensation. Equilibrium dissociation constants are derived independently by both CD and ITC methods for the interaction between protamine or mu with pDNA (K(d) = 0.6-1 microM). Thermodynamic data are also obtained by ITC, indicating strong charge-charge interactions. The interaction of protamine with pDNA takes place with decreasing entropy (-28.7 cal mol(-1) K(-1)); unusually, the interaction of mu with pDNA takes place with increasing entropy (Delta S degrees (bind) = 11.3 cal mol(-1) K(-1)). Although protamine and mu appear to destabilize pDNA double helix character to similar extents, according to CD thermal titration analyses, PCS studies show that interactions between mu and pDNA result in the formation of significantly more size-stable condensed particles than protamine. The enhanced flexibility and size stability of mu-DNA (MD) particles (80-110 nm) compared to protamine counterparts suggest that MD particles are ideal for use as a part of new nonviral gene delivery vectors.

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We have recently established a cancer-reactive human monoclonal antibody, GAH, with a positive ratio of over 90% against stomach cancer. GAH was formulated as polyethyleneglycol (PEG)-modified immunoliposomal doxorubicin (DXR) (ILD) and its efficacy was examined against gastrointestinal human cancers. In in vitro studies, a comparison of ILD with PEG-modified liposomal DXR (LD) demonstrated that ILD had dose-dependent cytotoxicity for GAH-reactive B37 cancer cells, but not LD. In concordance with this result, microscopic observations showed that ILD was bound to and GAH-dependently internalised by B37 cells. In in vivo studies, ILD exhibited significantly greater antitumour activity on cancer xenograft models than LD or free DXR. The relation between efficacy and antigen density was examined on 10 xenograft models bearing cancer cells with varying GAH reactivity. Immunoliposomal doxorubicin therapeutic activity correlated with the antigen density, with a minimum number being required. Also, ILD revealed strong antitumour activity on cancers with low sensitivity to DXR or LD, suggesting that ILD overcame the DXR resistance of antigen-positive cancer cells. Thus, these results show that GAH endows liposomes with targeting activity, resulting in strong efficacy against gastrointestinal cancers.

Effect of added salt on the three-phase behavior of microemulsion in water/octaethylene glycol dodecyl ether (C12EO8)/hexanol/decane and water/sucrose monododecanoate (SMD)/hexanol/ decane systems was investigated at 25 °C. The three-phase body is shifted to higher hexanol mixing ratio upon addition of KSCN, whereas the opposite tendency is observed upon addition of NaCl in the C12EO8 system. These phenomena can be explained by salting-out and salting-in effects, respectively. On the other hand, the three-phase body is shifted to higher hexanol mixing ratio upon addition of both inorganic salts in the SMD system. In the absence of oil, however, the effect of added salt on the clouding phenomena in the SMD system is similar to that in the C 12EO8 system. The mixing fraction of hexanol in the total surfactant (nonionic surfactant + hexanol) in the interface of micro-oil and water domains inside the middle-phase microemulsion is estimated according to the geometrical relation of a three-phase body in the space of compositions. As a result, the effect of added inorganic salt on the mixing fraction in the interface is opposite to that on the apparent mixing fraction of hexanol in the total surfactant to form the three-phase body in the SMD system. Consequently, this novel phenomenon can be explained by the change in the nature of excess oil phase or micro-oil domain due to the high solubility of hexanol in oil. LA961067W