liposome


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liposome

(lī`pəsōm', lĭp`ə–), microscopic, fluid-filled pouch whose walls are made of layers of phospholipidsphospholipid
, lipid that in its simplest form is composed of glycerol bonded to two fatty acids and a phosphate group. The resulting compound called phosphatidic acid contains a region (the fatty acid component) that is fat-soluble along with a region (the charged phosphate
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 identical to the phospholipids that make up cell membranes. Liposomes are used to deliver certain vaccines, enzymes, or drugs (e.g., insulin and some cancer drugs) to the body. When used in the delivery of certain cancer drugs, liposomes help to shield healthy cells from the drugs' toxicity and prevent their concentration in vulnerable tissues (e.g., the kidneys, and liver), lessening or eliminating the common side effects of nausea, fatigue, and hair loss. Liposomes are especially effective in treating diseases that affect the phagocytes of the immune system because they tend to accumulate in the phagocytes, which recognize them as foreign invaders. They have also been used experimentally to carry normal genes into a cell in order to replace defective, disease-causing genes (see gene therapygene therapy,
the use of genes and the techniques of genetic engineering in the treatment of a genetic disorder or chronic disease. There are many techniques of gene therapy, all of them still in experimental stages.
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). Liposomes are sometimes used in cosmetics because of their moisturizing qualities.

Liposomes were first produced in England in 1961 by Alec D. Bangham, who was studying phospholipids and blood clotting. It was found that phospholipids combined with water immediately formed a sphere because one end of each molecule is water soluble, while the opposite end is water insoluble. Water-soluble medications added to the water were trapped inside the aggregation of the hydrophobic ends; fat-soluble medications were incorporated into the phospholipid layer.

In some cases liposomes attach to cellular membranes and appear to fuse with them, releasing their contents into the cell. Sometimes they are taken up by the cell, and their phospholipids are incorporated into the cell membrane while the drug trapped inside is released. In the case of phagocytic cells, the liposomes are taken up, the phospholipid walls are acted upon by organelles called lysosomes, and the medication is released. Liposomal delivery systems are still largely experimental; the precise mechanisms of their action in the body are under study, as are ways in which to target them to specific diseased tissues.

liposome

[′lip·ə‚sōm]
(cell and molecular biology)
One of the fatty droplets occurring in the cytoplasm, particularly of an egg.
References in periodicals archive ?
In fact, many different liposome cell-targeting approaches have been investigated.
Backed by years' experience on liposome manufacturing and the available products, Creative Biostructure can support various applications and speculations including: diagnostic and therapeutic applications; basic studies of cell interactions, and recognition processes; model of action of certain substances; and delivery of new biotechnology products.
"The effect of free and liposome encapsulated clodronate on the hepatic mononuclear phagocyte system in the rat." Clinical & Experimental Immunology, 99(2): pp.269-275 (1995).
Li el al also found that PC in the form of liposome (LPCC) without SD induced apoptosis of MSCs (11).
Liposome particle size, vesicular structure and number of bilayers in the liposome membrane are among the analyses which are known to be critical and are evaluated in studies in the field of liposome technology.
Considering that the ABC phenomenon can interfere with liposome targeting to macrophages, thus causing an increase in the concentration of SbIII in these cells and a decrease in its blood levels, this study is proposed to evaluate the impact of the ABC phenomenon on the targeting of Sb to the liver and the spleen.
Pradhan et al., "In vivo analysis of biodegradable liposome gold nanoparticles as efficient agents for photothermal therapy of cancer," Nano Letters, vol.
Jadhav, "Novel methods for liposome preparation," Chemistry and Physics of Lipids, vol.
Mravljak et al., "The effect of lipid composition and liposome size on the release properties of liposomes-in-hydrogel," International Journal of Pharmaceutics, vol.
In the present study, a model liposome system composed of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) lipids is chosen to demonstrate the efficiency of the labeling with the novel iminothiolane-[sup.99m]Tc-tricarbonyl complex [29-31].
3 times a week with 2 mg/mouse of clodronate-loaded liposomes or control PBS-loaded liposomes for 6 weeks post T1D induction (Figure 7(a)).