Lipids/colloids

For example, the use of a conically shaped lipid, dioleoylphos-phatidylethanolamine (DOPE), in cationic liposomes helps the destabilization of the cellular membranes, leading to a more efficient delivery of plasmid DNA in cell culture.84 The structural diversity of the lipidic colloids offers great flexibility in their applications as drug delivery and drug targeting systems. 

Table 18.6 Physical Characteristics of Different Lipid Colloidal Systems ...

As the main suggested advantages of SLN over other lipidic colloidal carriers (e.g. controlled release, higher stability) are related to the solid state of the matrix lipid, physicochemical studies of the nanoparticles are crucial particularly for new compositions (e.g. lipid mixtures). 

Surface-active lipids-colloidal properties of the phospholipids... 

In special cases (as in colloidal solutions) some particles can be considered as essential and other particles as irrelevant , but in most cases the essential space will itself consist of collective degrees of freedom. A reaction coordinate for a chemical reaction is an example where not a particle, but some function of the distance between atoms is considered. In a simulation of the permeability of a lipid bilayer membrane for water [132] the reaction coordinate was taken as the distance, in the direction perpendicular to the bilayer, between the center of mass of a water molecule and the center of mass of the rest of the system. In proteins (see below) a few collective degrees of freedom involving all atoms of the molecule, describe almost all the... 

Has D ], K Tu and M L Klein 1997. Atomic-scale Molecular Dynamics Simulations of Lipid Membranes. Current Opinion in Colloid and Interfaee Seienee 2 15-26. 

Amphotericin B-induced ARF occurs in as many as 40% to 65% of patients treated with the conventional desoxycholate formulation.30 Nephrotoxicity is due to renal arterial vasoconstriction and distal renal tubule cell damage. Risk factors include high doses, treatment for at least 7 days, preexisting kidney dysfunction, and concomitant use of other nephrotoxic drugs.31 Three lipid-based formulations of amphotericin B have been developed in an attempt to decrease the incidence of ARF amphotericin B lipid complex, amphotericin colloidal dispersion, and liposomal amphotericin B. The range of... 

The absorption of drugs from the rectal [32] cavity has been studied in some detail. Muranishi et al. [34] have shown that a significant increase in the absorption and lymphatic uptake of soluble and colloidal macromolecules can be achieved by pretreating the rectal mucosal membrane with lipid-nonionic surfactant mixed micelles. They found no evidence of serious damage of the mucosal membrane. Davis [30] suggested that the vaginal cavity could be an effective delivery site for certain pharmaceuticals, such as calcitonin, used for the treatment of postmenopausal osteoporosis. 

Hydrophobically modified HA derivatives,91 obtained through the partial esterification of the HA carboxyl groups with methylprednisolone (45% in HYCp45 and 60% in HYCp60),92 have been deeply studied 93 A key point prior to any in vivo study of the biomaterial is the assessment of the so-called "stealth character" of the species itself. Such characteristic corresponds to be invisible towards the immune system, so that colloids are not recognized as foreign objects by body fluid components, as plasma proteins fibrinogen, BSA and lipidic components.94,95... 

Westesen and Siekmann [11] used suspensions of colloidal solid lipid particles as well as lyophilizates as delivery systems for the parenteral administration of the drug for its particle morphology determination. 

It is well known that liposomes are good candidates for controlled reactions. As lipid-based colloids, they have been used to mimic biomineralization processes [99,100], while as restricted volumes, they have been used as microreactors to synthesize... 

ABLC = Amphotericin B Lipid Complex ABCD = Amphotericin B Colloidal Dispersion L-AMB = Liposomal Amphotericin B... 

Lipid-associated formulations of amphotericin B, liposomal amphotericin B (AmBisome) and amphotericin B lipid complex (Abelcet) have been approved for use in proven cases of candidiasis however, patients with invasive candidiasis have also been treated successfully with amphotericin B colloid dispersion (Amphotec or Amphocil). The lipid-associated formulations are less toxic but as effective as amphotericin B deoxycholate. 

Candida albicans, C. tropicalis, C parapsilosis and resolution of signs and symptoms of infection Remove existing central venous catheters when feasible, plus Amphotericin B IV 0.6 mg/k day or Fluconazole IV/po 6 mg/kg/day or An echinocandin or Amphotericin B IV 0.7 mg/kg/day plus fluconazole IV/po 800 mg/day Patients intolerant or refractory to other therapf Amphotericin B lipid complex IV 5 m k day Liposomal amphotericin B IV 3-5 mg/kg/day Amphotericin B colloid dispersion IV 2-6 mg/k day (continued)... 

Addition of the protein lysozyme to DC89PC dispersions resulted in the formation of conical tubules in ethanol-water solution.149 The scanning electron micrograph in Figure 5.37 shows that precipitate from this system is primarily composed of these cones, with a smaller number of cylinders. The cones exhibit more pronounced helical ridges on their exteriors than pure lipid cylinders, suggesting that protein selectively associates to the helical defects in a similar manner as the colloidal particles discussed above. 

With respect to SCF models that focus on the tail properties only (typically densely packed layers of end-grafted chains), the molecularly realistic SCF model exemplified in this review needs many interaction parameters. These parameters are necessary to obtain colloid-chemically stable free-floating bilayers. A historical note of interest is that it was only after the first SCF results [92] showed that it was not necessary to graft the lipid tails to a plane, that MD simulations with head-and-tail properties were performed. In the early MD simulations (i.e. before 1983) the chains were grafted (by a spring) to a plane it was believed that without the grafting constraints the molecules would diffuse away and the membrane would disintegrate. Of course, the MD simulations that include the full head-and-tails problem feature many more interactions than the early ones. 

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