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 ?
The liposome products include Clodrosome (clodronate liposomes), Encapsome (plain liposomes for clodronate liposomes control), Doxosome(TM) (doxorubicin liposomes), Immunosome(TM) (reactive liposomes for antibody, protein conjugation), Immunodox(TM) (reactive liposomes for antibody, protein conjugation containing doxorubicin), Immunogene(TM) (reactive liposomes for antibody, protein conjugation containing genetic material), Immunofluor(TM) (reactive liposomes for antibody, protein conjugation containing fluorescent molecules for tracking), Genesome(TM) (liposomal DNA and RNA), Fluoroliposome(TM) (fluorescent liposomes), ATPsome(TM) (ATP liposomes), Cellsome(TM) (plain liposomes as artificial cell models) and Cosmesome(TM) (liposomes used in dermatology).
The company offers innovative primary and secondary antibodies, peptides, antibody reagents, assay kits, and liposome reagents, as well as custom services.
According to the beauty industry liposomes are capable of transporting active ingredients deep into the skin and release the active ingredients so that they can alter the skin's structure by rejuvenating and smoothing the skin.
Liposomes can encapsulate and release both hydrophobic and hydrophilic active compounds.
There are five extracts in the current Liposome Herbasec range, which are standardized for specific phytochemicals.
16) Negative stain electron microscopy is a useful method for addressing questions concerning size distribution of the liposome, and it is a reliable technique that is simple to perform and requires only limited specialized equipment.
Because each liposome contains hundreds of thousands to perhaps millions of marker molecules, there is a large amplification effect," says Durst.
The pathogens were drawn to the antibodies on the liposome membrane, causing the membrane to react and rupture, releasing marker dye molecules.
Researchers at Children's Hospital Boston envision a new way for women to protect themselves before sex: an applicator filled with specially formulated fatty particles called liposomes.
The liposome researchers have made rapid progress in only a few years and "have identified a product that :night have a great deal of value," says Phillip J.
Food and Drug Administration (FDA) has granted orphan drug designation for Marqibo([R]) (vincristine sulfate liposomes injection) in the treatment of adult patients with acute lymphoblastic leukemia (ALL).