Aquaporins are water channels present in plants, bacteria and human skin. They are highly conserved structures that are integral membrane proteins from a larger family of major intrinsic proteins.
A Aquaporins are water channels present in plants, bacteria and human skin. They are highly conserved structures that are integral membrane proteins from a larger family of major intrinsic proteins. The 2003 Nobel Prize for chemistry was awarded to Peter Agre and Roderick MacKinnon for work on aquaporins and ion channels.
These channels conduct water in and out of the cell while preventing the passage of ions and some solutes. They are composed of a six transmembrane alpha helical structures arranged in a right-handed bundle. Aquaporins form tetramers in the cell membrane and control the transport of water, as well as glycerol, carbon dioxide, ammonia and urea.
The primary aquaporin in the epidermis is aquaporin-3. It is found in the basal and suprabasal layers of the epidermis, but not in the stratum corneum. Aquaporin-3 is also known as an aquaglyceroporin, since it is capable of transporting glycerol.
Aquaporin-3 expression is also increased in human skin diseases with elevated transepidermal water loss.
Q How many dispensing physicians are there in the United States?
A Sources inside the cosmetic industry claim that there are 10,000 dispensing physicians in the United States, of which 44 percent are dermatologists, with the remainder being largely plastic surgeons and a few gynecologists and family practitioners.
Growth in this segment of the cosmetics industry is causing many cosmetic manufacturers to develop products for dispensing by physicians, since a growth area could be transformed into a large segment with proper marketing. Within a few years, physicians - especially dermatologists - will be bombarded with products to dispense.
Other pressures are causing the cosmetics industry to look for new retail outlets. With fewer department store sales opportunities, companies are eyeing the medical office. Physicians looking to supplement their income are providing a captive patient audience for product sales.
Furthermore, cosmetic companies can introduce products for sale in medical offices without paying the expensive rent required for department store sales.
Zoe Diana Draelos, M.D., is a Dermatology Times editorial adviser and investigator, Dermatology Consulting Services, High Point, N.C.
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