Lipid composition effect

Seo PR, Teksin ZS, Kao JP, Polli JE (2006) Lipid composition effect on permeability across PAMPA. Eur J Pharm Sci 29 259-68. 

The effectiveness of the light in causing structural disturbances correlated with the effectiveness of light in mediating the photodestruction of chlorophyll. The structural disintegration was not related to the effect of the pyridazinones on the lipid composition of the plastid membrane si.nce structural changes did not occur in the presence of BASF 13 338 even though the lipid compositional effects had occurred. 

Several studies have been performed in order to investigate the effect of liposomal size (Hirano and Hunt, 1985), lipid composition (Senior and Gregoriadis, 1982 Hirano et al., 1985), and lipid dose (Ellens et al., 1983, Kim et al., 1987) on the fate of liposomes after intraperitoneal administration. In the size range studied (0.048-0.72 Min), no size-dependent absorption could be expected (Hirano and Hunt, 1985). Particles larger than 22.5 pm are not expected to enter the lymphatic capillaries (Allen, 1956). After intraperitoneal administration of multivesicular liposomes (19 + 7 ym), Kim and Howell (1987a) and Kim et al. (1987) showed that liposomal entrapment of Ara-C prolongs the half-Ufe of the drug in the peritoneal... 

Barza, M., Stuart, M., and Szoka, F. (1987). Effect of size and lipid composition on the pharmacokinetics of intravitreal liposomes, Invest. Ophthalmol. Visual Sci., 28, 893-900. 

A. (1990b). Effect of lipid composition on the in vivo integrity of doxorubicin-containing liposomes. Two pathways for sustained release of doxorubicin. Submitted. 

The lipid content of the membranes can be varied, allowing systematic examination of the effects of varying lipid composition on certain functions. For instance, vesicles can be made that are composed solely of phosphatidylchohne or, alternatively, of known mixtures of different phospholipids, glycohpids, and cholesterol. The fatty acid moieties of the lipids used can also be varied by employing synthetic lipids of known... 

The increase of negative charge from 0.6% to 1.1% wt/vol in dodecane (modeling the expected increase between BBM and BBB lipid compositions see Table 7.1) shows further increases to the permeabilities of the dramatically affected molecules, especially amiloride, which becomes effectively more permeable than piroxicam. 

At a more molecular level, the influences of the composition of the membrane domains, which are characteristic of a polarized cell, on diffusion are not specifically defined. These compositional effects include the differential distribution of molecular charges in the membrane domains and between the leaflets of the membrane lipid bilayer (Fig. 3). The membrane domains often have physical differences in surface area, especially in the surface area that is accessible for participation in transport. For example, the surface area in some cells is increased by the presence of membrane folds such as microvilli (see Figs. 2 and 6). The membrane domains also have differences in metabolic selectivity and capacity as well as in active transport due to the asymmetrical distribution of receptors and transporters. 

Christie, W. W. (1981) The effects of diet and other factors on lipid composition of mminant tissues and milk. In Progress in Lipid Research. Supplement 1. Lipid Metabolism in Ruminant Animals (Ed. Christie, W. W.), Pergamon Press, Oxford, pp. 193 226. 

Devineau, J. and C. Amiard Triquet 1985. Patterns of bioaccumulation of an essential trace element (zinc) and a pollutant metal (cadmium) in larvae of the prawn Palaemon serratus. Mar. Biol. 86 139-143. Dib, A., J.P Clavel, and J.P. Carreau. 1989. Effects of gamma-linolenic acid supplementation on lipid composition of liver microsomal membranes. I. Pregnant rats fed a zinc-deficient diet and those fed a balanced one. Jour. Clin. Biochem. Nutr. 6 95-102. 

Grenier, G., L. Protean, J.P. Marier, and G. Beaumont. 1987. Effects of a sublethal concentration of atrazine on the chlorophyll and lipid composition of chlorophyll-protein complexes of Lemna minor. Plant Physiol. Biochem. 25 409-413. 

Bienvenue, E., Boudou, A., Desmazes, J. P., Gavach, C., Georgescauld, D., Sandeaux, J., Sandeaux, R. and Seta, P. (1984). Transport of mercury compounds across bimolecular lipid membranes effect of lipid composition, pH and chloride concentration, Chem.-Biol. Interact., 48, 91-101. 

Oishi S, Hiraga K. 1982. Effects of monoesters of 0-phthalic acid on serum lipid composition of rats. Toxicol Lett 14 79-84. 

K. Miyajima, S. Tanikawa, M. Asano, and K. Matsuzaki. Effects of absorption enhancers and lipid composition on drug permeability through the model membrane using stratum corneum lipids. Chem. Pharm. Bull. 42 1345-1347 (1994). 

Recently, the effect of the lipid composition on the permeability in PAMPA was investigated [129], By varying the phosphate head group and the saturation degree of the acyl chain, differences in transport were observed for a set of five model compounds, which was due to changes in membrane fluidity and ion pairing [129],... 

Figure 2 (A) Effect of incubation temperature on uptake of doxorubicin into 200 nm EPC/cholesterol (55 45 mol/mol) large unilamellar vesicles (LUVs) exhibiting a transmembrane pH gradient (pH 4 inside, 7.8 outside). Doxorubicin was added to LUVs (D/L = 0.3 wt wt) equilibrated at 21°C, 37°C, and 60°C. (B) Effect of cholesterol on the uptake of doxorubicin at 20 into lOOnm LUVs exhibiting a transmembrane pH gradient (pH 4.6 inside, 7.5 outside). Lipid compositions were EPC and EPC/cholesterol (1 1 mol/mol). The initial drug-to-lipid ratio was 100 nmol/pmol. Source Prom Refs. 12 (A), 21 (B).

Kirby C, Gregoriadis G. The effect of lipid composition of small unilamellar liposomes containing melphalan and vincristine on drug clearance after injection into mice. Biochem Pharmacol 1983 32(4) 609. 

Li WL, et al. Low-pH-sensitive poly(ethylene glycol) (PEG)-stabilized plasmid nanolipoparticles effects of PEG chain length, lipid composition and assembly conditions on gene delivery. J Gene Med 2005 7 67. 

There is no doubt that cerebral lipids, and EEA-derived LC-PUFAs in particular, have significant direct and indirect actions on cerebral function. Not only does the lipid composition of neural membranes affect the function of their embedded proteins, but also many LC-PUFAs are converted to neurally active substances. There is good evidence that psychiatric illness is associated with depletion of EFAs and, crucially, that supplementation can result in clinical amelioration. Ar well as challenging traditional views of aetiology and therapeutics in psychiatry, the clinical trial data may herald a simple, safe and effective adjunct to our standard treatments for many disabling conditions. 

Lipid membranes are quite deformable, allowing water and head groups into their interiors when perturbed. A "water defect" is shown in Figure 1C, where water and lipid head groups enter the hydrophobic interior of only one of the bilayer leaflets. Figure ID shows a "water pore," where both leaflets are perturbed. At the molecular level, pore and defect formation are directly related to specific lipid-lipid interactions. It is important to understand the free energy required for pore formation in membranes and the effect of lipid composition on the process. In Section 3 of this chapter, we review recent MD studies of the thermodynamics of pore formation. 

The answer is E. Anesthetics are highly lipid-soluble and experiments with isolated membranes indicate that these molecules can dissolve in the hydrophobic center of the membrane bilayer. This causes a measurable increase in the membrane fluidity by disrupting the packed structure of phospholipids tails. This is considered to be the main, direct mechanism by which this class of drugs inhibits neurotransmission (pain sensations) in neurons. Hallucinogens and opiates may also affect membrane fluidity, but their effects occur by indirect mechanisms, resulting from changes in the protein or lipid composition of the membranes. 

Awad, T. B. and J. P. Chattopadhyay. Effect of dietary fats on the lipid composition and enzyme activities of rat cardiac sarcolemma. J Nutr 1983 113(9) 1878-1883. 

Anon. Clinical trials on AIDS start. Reprowatch 1999 1—28 6—11. Garcia-Fuentes, E., A. Gil-Villarino, M. F. Zafra, and E. Garcia-Peregrin. Changes in plasma lipid composition induced by coconut oil. Effects of dipyridamole. J Physiol Biochem 2002 58(1) 33-41. 

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