Liposomes have been widely investigated since 1970 as drug carriers for improving the delivery of therapeutic agents to specific sites in the body. As a result, numerous improvements have been made, ...thus making this technology potentially useful for the treatment of certain diseases in the clinics. The success of liposomes as drug carriers has been reflected in a number of liposome-based formulations, which are commercially available or are currently undergoing clinical trials. The current pharmaceutical preparations of liposome-based therapeutic systems mainly result from our understanding of lipid-drug interactions and liposome disposition mechanisms. The insight gained from clinical use of liposome drug delivery systems can now be integrated to design liposomes that can be targeted on tissues, cells or intracellular compartments with or without expression of target recognition molecules on liposome membranes. This review is mainly focused on the diseases that have attracted most attention with respect to liposomal drug delivery and have therefore yielded most progress, namely cancer, antibacterial and antifungal disorders. In addition, increased gene transfer efficiencies could be obtained by appropriate selection of the gene transfer vector and mode of delivery.
A pulsed plasma enhanced chemical vapor deposition (PECVD) reactor is used for the preparation of thin polyacetylene films. A theoretical model based on the mass transport characteristics of the ...reactor is developed in order to correlate with experimentally obtained spatial deposition profiles for the acetylene plasma polymer film deposited within the cylindrical reactor. Utilizing a free radical mechanism with gas phase initiation of the polymerization reaction as the rate controlling step, a system parametric study is performed to predict the Peclet number range of operation for the pulsed PECVD reactor. This parametric study indicates radical decay by diffusion to the reactor walls to be the significant physical phenomenon in the system. It is concluded that a quasi-steady-state model is a good tool for predicting the important mass transfer phenomena occurring in the pulsed plasma reactor.
A pulsed plasma source for deposition of thin polymer films was modeled numerically with the one-dimensional (1-D) time dependent fluid transport equations describing an explosion for an ideal gas. ...Initial number density, explosion temperature, and velocity were made consistent with values in an experimental reactor. These quantities as well as pressure and fluence were modeled for a distance of 2 m and for a time duration of 93 /spl mu/s. The trajectory for maximum pressure calculated from the model was observed to be consistent with the experimentally measured trajectory of maximum emitted light from an acetylene plasma. Measured axial profiles of areal density for the deposited polymer films were compared with modeled fluence.
Od 1970. godine liposomi se intenzivno istražuju kao nosači ljekovitih tvari za isporuku u određene dijelova organizma. Unapređenje i razvoj liposoma omogućili su njihovu kliničku primjenu u terapiji ...određenih bolesti. Na tržištu je prisutan određen broj ljekovitih oblika na bazi liposoma, a dio je još u kliničkim pokusima. Svi su oni rezultat boljeg razumjevanja raspodjele liposoma i interakcija između lipida i ljekovite tvari. Moguće je pripremiti liposome koji se mogu usmjeriti u određena tkiva, stanice ili međustanične prostore, sa ili bez vezanih molekula za prepoznavanje na površini membrane. Ovaj revijalni članak uglavnom obuhvaća liposome za terapiju karcinoma, bakterijskih i gljivičnih infekcija jer je u tim područjima primjena liposoma najviše opravdana i stoga najviše istraživana. Osim toga, pravilnim izborom vektora za prijenos gena i načina isporuke može se povećati i učinkovitost prijenosa gena.
