1-2-dielaidoylphosphatidylethanolamine and 1-2-dilauroylphosphatidylcholine

Additive force fields are designed to account for induced electronic polarization in a mean-field average way, using effective empirical fixed charges. The limitation of this approximation is cause for serious concerns, particularly in the case of lipid membranes, where the molecular environment undergoes dramatic variations over microscopic length scales. A polarizable force field based on the classical Drude oscillator offers a practical and computationally efficient framework for an improved representation of electrostatic interactions in molecular simulations. Building on the first-generation Drude polarizable force field for the dipalmitoylphosphatidylcholine 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) molecule, the present effort was undertaken to improve this initial model and expand the force field to a wider range of phospholipid molecules. New lipids parametrized include dimyristoylphosphatidylcholine (DMPC), dilauroylphosphatidylcholine (DLPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), dipalmitoylphosphatidylethanolamine (DPPE), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). The iterative optimization protocol employed in this effort led to lipid models that achieve a good balance between reproducing quantum mechanical data on model compound representative of phospholipids and reproducing a range of experimental condensed phase properties of bilayers. A parametrization strategy based on a restrained ensemble-maximum entropy methodology was used to help accurately match the experimental NMR order parameters in the polar headgroup region. All the parameters were developed to be compatible with the remainder of the Drude polarizable force field, which includes water, ions, proteins, DNA, and selected carbohydrates.

Topics: Diffusion; Lipid Bilayers; Molecular Dynamics Simulation; Phosphatidylcholines; Phosphatidylethanolamines; Phospholipids; Quantum Theory; Thermodynamics

A plasmid pLTR-DT which contained a gene for diphtheria toxin A-chain (DT-A) under the control of the long terminal repeat (LTR) of bovine leukemia virus (BLV) (BLV-LTR) in the multicloning site of pUC-18 was entrapped in cationic liposomes composed of N-(alpha-trimethylammonioacetyl)-didodecyl-D-glutamate chloride (TMAG), dioleoyl phosphatidylethanolamine (DOPE) and dilauroyl phosphatidylcholine (DLPC) (1:2:2, molar ratio) (TMAG-liposome), and their antitumor effect on BLV-infected tumor cells was examined in vivo. The cationic TMAG-liposome containing pLTR-DT was successively injected into the tumor transplanted to nude mice. The growth of tumor was significantly inhibited by the injection of cationic TMAG-liposome containing pLTR-DT. On the other hand, TMAG-liposome containing pUC18 plasmids showed no such effect. These results suggest that a DT-A expression plasmid under the control of BLV-LTR is highly toxic to the BLV-infected tumor cells, and that the cationic liposomes, such as TMAG-liposome, may be efficient transfection reagent for BLV-infected tumor cells and can be utilized for DT-A gene delivery into BLV-infected tumor cells in vivo.

Topics: Animals; Antineoplastic Agents; Cattle; Cells, Cultured; Diphtheria Toxin; Drug Carriers; Enzootic Bovine Leukosis; Gene Transfer Techniques; Genetic Therapy; Glutamates; Kidney; Leukemia Virus, Bovine; Liposomes; Mice; Mice, Nude; Peptide Fragments; Phosphatidylcholines; Phosphatidylethanolamines; Plasmids; Recombinant Proteins; Repetitive Sequences, Nucleic Acid; Sheep; Transplantation, Heterologous

To transfer foreign genes into myoblasts in primary culture, we found cationic multilamellar liposomes to be a useful mediator. When the cells were transfected with 2 micrograms of the plasmid pRSV-luc encapsulated into 50 nmol of our cationic multilamellar liposomes that had been prepared from N-(alpha-trimethylammonioacetyl)-didodecyl-D-glutamate chloride, dilauroyl phosphatidylcholine, and dioleoyl phosphatidylethanolamine in a molar ratio of 1:2:2, luciferase was expressed with high efficiency without cytotoxicity. When the cells were transfected with the plasmid pRSV-lacZ encapsulated into the same liposomes, 0.7% of the cultured myoblasts expressed beta-galactosidase without cytotoxicity. This is the first successful instance of introducing foreign genes into primary cultures of myoblasts by means of liposomes.

Topics: Animals; Animals, Newborn; Cells, Cultured; Drug Carriers; Gene Transfer Techniques; Glutamates; Liposomes; Luciferases; Muscle, Skeletal; Phosphatidylcholines; Phosphatidylethanolamines; Plasmids; Rats; Recombinant Proteins; Transfection

A simple procedure for the preparation of cationic multilamellar vesicles (MLV) consisting of N-(alpha-trimethylammonioacetyl)-didodecyl-D-glutamate chloride, dilauroyl phosphatidylcholine, and dioleoyl phosphatidylethanolamine in a molar ratio of 1:2:2 was devised. When bacteriophage lambda DNA was encapsulated into these liposomes, entrapment efficiency was found to be nearly 100%, and digestibility of the DNA was less than 10%. Upon encapsulation of the plasmid pCH110 into cationic MLV, efficient expression was comparable to that obtained with cationic vesicles prepared by reverse-phase evaporation method (REV). Cytotoxicity of the present liposomes was less than that of cationic REV and far less than that of Lipofectin.

Topics: Animals; Bacteriophage lambda; Cell Line; Cell Survival; Chlorocebus aethiops; Cloning, Molecular; DNA, Viral; Drug Carriers; Escherichia coli; Gene Transfer Techniques; Genes, Bacterial; Glutamates; Liposomes; Pentosyltransferases; Phosphatidylcholines; Phosphatidylethanolamines; Plasmids