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Encyclopedia > Hyaluronan
The repeating disaccharide unit of hyaluronan
The repeating disaccharide unit of hyaluronan

Hyaluronan (also called hyaluronic acid or hyaluronate) is a non-sulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues. It is one of the chief components of the extracellular matrix, contributes significantly to cell proliferation and migration, and may also be involved in the progression of some malignant tumors. The average 70 kg man has roughly 15 grams of hyaluronan in his body, one third of which is turned over (degraded and synthesised) every day.[1] Image File history File links Size of this preview: 800 × 341 pixelsFull resolution (953 × 406 pixel, file size: 13 KB, MIME type: image/png) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Size of this preview: 800 × 341 pixelsFull resolution (953 × 406 pixel, file size: 13 KB, MIME type: image/png) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Chondroitin sulfate Hyaluronan Glycosaminoglycans (GAGs) or mucopolysaccharides are long unbranched polysaccharides consisting of a repeating disaccharide unit. ... Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, muscle, and nervous tissue. ... In zootomy, epithelium is a tissue composed of a layer of cells. ... The nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and processes input from the senses, and initiates actions. ... Tumor or tumour literally means swelling, and is sometimes still used with that meaning. ...

Contents

Functions

Until the late 1970s, hyaluronan was described as a "goo" molecule, a ubiquitous carbohydrate polymer that is part of the extracellular matrix. For example, hyaluronan is a major component of the synovial fluid and was found to increase the viscosity of the fluid. Along with lubricin, it is one of the fluid's main lubricating components. The 1970s decade refers to the years from 1970 to 1979. ... Lactose is a disaccharide found in milk. ... Synovial fluid is a thin, stringy fluid found in the cavities of synovial joints. ... Lubricin is a glycoprotein encoded by the PRG4 gene. ...


Hyaluronan is an important component of articular cartilage, where it is present as a coat around each cell (chondrocyte). When aggrecan monomers bind to hyaluronan in the presence of link protein, large highly negatively charged aggregates form. These aggregates imbibe water and are responsible for the resilience of cartilage (its resistance to compression). The molecular weight (size) of hyaluronan in cartilage decreases with age however the amount increases.[2] Cartilage is a type of dense connective tissue. ... Chondrocytes (< Greek chondros cartilage + kytos cell) are the only cells found in cartilage. ... Aggrecan, or large aggregating proteoglycan, is a proteoglycan, or a protein modified with carbohydrates; the human form of the protein is 2316 amino acids long and can be expressed in multiple isoforms due to alternative splicing. ... For the band see Resilience (band) Resilience generally means the ability to recover from (or to resist being affected by) some shock, insult, or disturbance. ... Cartilage is a type of dense connective tissue. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... Cartilage is a type of dense connective tissue. ...


Hyaluronan is also a major component of skin, where it is involved in tissue repair. When skin is excessively exposed to UVB rays, it becomes inflamed (sunburn) and the cells in the dermis stop producing as much hyaluronan and increase the rate of its degradation. Hyaluronan degradation products also accumulate in the skin after UV exposure.[3] Beyond overall skin structure, refer below to: See-also. ... Beyond overall skin structure, refer below to: See-also. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ...


While it is abundant in extracellular matrices, hyaluronan also contributes to tissue hydrodynamics, movement and proliferation of cells, and participates in a number of cell surface receptor interactions, notably those including its primary receptor, CD44. Upregulation of CD44 itself is widely accepted as a marker of cell activation in lymphocytes. Hyaluronan's contribution to tumor growth may be due to its interaction with CD44. CD44 participates in cell adhesion interactions required by tumor cells. The CD44 protein is a cell-surface glycoprotein involved in cell-cell interactions, cell adhesion and migration. ...


Although hyaluronan binds to CD44, there are evidence to support that hyaluronan degradation products transduce their inflammatory signal through Toll-like receptor 2 (TLR2), TLR4 or both TLR2 and TLR4 in macrophages and dendritic cells. TLR and hyaluronan play a role in innate immunity. The CD44 protein is a cell-surface glycoprotein involved in cell-cell interactions, cell adhesion and migration. ... TLR-2 is the name for a biomolecule, which plays a role in the human immune system. ... TLR-2 is the name for a biomolecule, which plays a role in the human immune system. ... TLR 4 is a toll-like receptor. ... TLR-2 is the name for a biomolecule, which plays a role in the human immune system. ... TLR 4 is a toll-like receptor. ... Macrophages (Greek: big eaters) are cells found in tissues that are responsible for phagocytosis of pathogens, dead cells and cellular debris. ... Dendritic cells (DC) are immune cells and form part of the mammal immune system. ... Innate immunity is immunity that the body possesses naturally, as opposed to adaptive immunity. ...


Structure

The chemical structure of hyaluronan was determined in the 1950s in the laboratory of Karl Meyer. Hyaluronan is a polymer of disaccharides themselves composed of D-glucuronic acid and D-N-acetylglucosamine, linked together via alternating β-1,4 and β-1,3 glycosidic bonds. Hyaluronan can be 25,000 disaccharide repeats in length. Polymers of hyaluronan can range in size from 5,000 to 20,000,000 Da in vivo. The average molecular weight in human synovial fluid is 3−4 million Da and hyaluronan purified from human umbilical cord is 3,140,000 Da.[4] Chemical structure refers to the spatial arrangement of atoms in a molecule and the chemical bonds that hold the atoms together. ... This does not cite any references or sources. ... Karl Meyer (b. ... Sucrose, a common disaccharide A disaccharide is a sugar (a carbohydrate) composed of two monosaccharides. ... Glucuronic acid (from Greek γλυκερός - sweet) is a carboxylic acid. ... N-Acetylglucosamine (N-Acetyl-D-Glucosamine, or GlcNAc, or NAG) is a monosaccharide derivative of glucose. ... In chemistry, a glycosidic bond is a certain type of functional group that joins a carbohydrate (sugar) molecule to an alcohol, which may be another carbohydrate. ... The unified atomic mass unit (u), or Dalton (Da), is a small unit of mass used to express atomic and molecular masses. ... Synovial fluid is a thin, stringy fluid found in the cavities of synovial joints. ... In placental mammals, the umbilical cord is a tube that connects a developing embryo or fetus to its placenta. ...


Hyaluronan is energetically stable in part because of the stereochemistry of its component disaccharides. Bulky groups on each sugar molecule are in sterically favored positions while the smaller hydrogens assume the less favorable axial positions. The different types of isomers. ...


Synthesis

Hyaluronan is synthesized by a class of integral membrane proteins called hyaluronan synthases, of which vertebrates have three types: HAS1, HAS2, and HAS3. These enzymes lengthen hyaluronan by repeatedly adding glucuronic acid and N-acetylglucosamine to the nascent polysaccharide as it is extruded through the cell membrane into the extracellular space. An Integral Membrane Protein (IMP) is a protein molecule (or assembly of proteins) that is permanently attached to the biological membrane. ... Hyaluronan synthases (HAS) are membrane-bound enzymes which produce the glycosaminoglycan hyaluronan at the cell surface and extrude it through the membrane into the extracellular space. ... The cell membrane (also called the plasma membrane, plasmalemma or phospholipid bilayer) is a semipermeable lipid bilayer common to all living cells. ...


Degradation

Hyaluronan is degraded by a family of enzymes called hyaluronidases. In humans, there are at least seven types of hyaluronidase-like enzymes, several of which are tumor suppressors. The degradation products of hyaluronan, the oligosaccharides and very low molecular weight hyaluronan, exhibit pro-angiogenic properties. In addition, recent studies showed that hyaluronan fragments, not native high molecular mass of hyaluronan, can induce inflammatory responses in macrophages and dendritic cells in tissue injury and in skin transplant rejection. Hyaluronidase The hyaluronidases (EC 3. ...


Medical applications

Hyaluronan is naturally found in many tissues of the body such as skin, cartilage, and the vitreous humor. It is therefore well suited to biomedical applications targeting these tissues. The first hyaluronan biomedical product, Healon, was developed in the 1970s and 1980s and is approved for use in eye surgery (i.e., corneal transplantation, cataract surgery, glaucoma surgery and surgery to repair retinal detachment). Other biomedical companies also produce brands of hyaluronan for ophthalmic surgery.[5][6] Eye surgery in the middle ages. ... Cornea Transplant Another Cornea Transplant, approximately one week after surgery. ... Human eye cross-sectional view, showing position of human lens. ... Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. ...


Hyaluronan is also used to treat osteoarthritis of the knee.[7] Such treatments, called viscosupplementation, are administered as a course of injections into the knee joint and are believed to supplement the viscosity of the joint fluid thereby lubricating the joint, cushioning the joint and producing an analgesic effect. It has also been suggested that hyaluronan has positive biochemical effects on cartilage cells. However, some placebo controlled studies have cast doubt on the efficacy of hyaluronan injections, and hyaluronan is recommended primarily as a last alternative to surgery.[8][9] Oral use of hyaluronan has been lately suggested although effectiveness needs to be demonstrated. Some preliminary clinical studies exist that suggest that oral administration of Hyaluronan has a positive effect on osteoarthritis. Osteoarthritis / Osteoarthrosis (OA, also known as degenerative arthritis, degenerative joint disease, arthrosis or in more colloquial terms wear and tear), is a condition in which low-grade inflammation results in pain in the joints, caused by wearing of the cartilage that covers and acts as a cushion inside joints. ... Chondrocytes (< Greek chondros cartilage + kytos cell) are the only cells found in cartilage. ...


Due to its high biocompatibility and its common presence in the extracellular matrix of tissues, hyaluronan is gaining popularity as a biomaterial scaffold in tissue engineering research.[10][11] Biocompatibility is the ability of a material to perform with an appropriate host response in a specific application. ... In biology, extracellular matrix (ECM) is any material part of a tissue that is not part of any cell. ... In surgery, a biomaterial is a synthetic or natural material used to replace part of a living system or to function in intimate contact with living tissue. ... Scaffold may refer to: scaffolding as used in construction A gallows The Scaffold, UK musical group Scaffold - GNOME Development Environment Scaffold (Protein ECM) This is a disambiguation page — a navigational aid which lists pages that might otherwise share the same title. ... Tissue engineering is the use of a combination of cells, engineering or tissue-matrix materials, and suitable biochemical factors to improve or replace biological functions. ...


In some cancers, hyaluronan levels correlate well with malignancy and poor prognosis. Hyaluronan is thus often used as a tumor marker for prostate and breast cancer. It may also be used to monitor the progression of the disease. Tumor markers are substances found in the blood, urine or body tissues that can be elevated in cancer. ... Prostate cancer is a disease in which cancer develops in the prostate, a gland in the male reproductive system. ... Breast cancer is cancer of breast tissue. ...


Hyaluronan may also be used postoperatively to induce tissue healing, notably after cataract surgery. Current models of wound healing propose that larger polymers of hyaluronic acid appear in the early stages of healing to physically make room for white blood cells, which mediate the immune response. Human eye cross-sectional view, showing position of human lens. ... White Blood Cells is also the name of a White Stripes album. ... A request has been made on Wikipedia for this article to be deleted in accordance with the deletion policy. ...


In 2007, the EMEA extended its approval of Hylan GF-20 as a treatment for ankle and shoulder osteoarthritis pain.[12] The European Medicines Agency (EMEA) is a European agency for the evaluation of medicinal products. ...


Cosmetic applications

Hyaluronan is a common ingredient in skin care products.


In 2003 the FDA approved hyaluronan injections for filling soft tissue defects such as facial wrinkles. Restylane is a common trade name for the product. Hyaluronan injections temporarily smooth wrinkles by adding volume under the skin, with effects typically lasting for six months. People who have been on any blood medication with in the last five years should not inject this drug until the five year span is over. This drug is also not good for the elderly because it can cause memory loss. Restylane is a gel of hyaluronic acid used in plastic surgery. ...


Etymology

Hyaluronic acid is derived from hyalos (Greek for vitreous) and uronic acid because it was first isolated from the vitreous humor and possesses a high uronic acid content. The Fischer projections of glucose and glucuronic acid. ... Vitreous humour is the clear gel that fills the eyeball, lying between the lens and the retina in the eye. ...


The term hyaluronate refers to the conjugate base of hyaluronic acid. Because the molecule typically exists in vivo in its polyanionic form, it is most commonly referred to as hyaluronan. Within the Brønsted-Lowry (protonic) theory of acids and bases, a conjugate acid is the acid member, HX, of a pair of two compounds that transform into each other by gain or loss of a proton. ...


References

  1. ^ Stern R (August 2004). "Hyaluronan catabolism: a new metabolic pathway". Eur J Cell Biol 83 (7): 317-25. PMID 15503855. Retrieved on 2007-06-12. 
  2. ^ Holmes et al. (1988) Hyaluronic acid in human articular cartilage. Age-related changes in content and size. Biochem J 250:435-441.
  3. ^ Averbeck M et al. (2007) Differential regulation of hyaluronan metabolism in the epidermal and dermal compartments of human skin by UVB irradiation. J Invest Dermatol 127:687-697.
  4. ^ Saari H et al. (1993) Differential effects of reactive oxygen species on native synovial fluid and purified human umbilical cord hyaluronate. Inflammation 17:403-415.
  5. ^ http://www.alconlabs.com/us/aj/products/Surgical_Cataract/A251_Viscoelastics.jhtml
  6. ^ http://www.bausch.com.br/br/resource/surgical/cataract/amviscstatement.jsp
  7. ^ Puhl W; Scharf P (July 1997). "Intra-articular hyaluronan treatment for osteoarthritis". Ann Rheum Dis 56 (7): 637-40. PMID 9486013. Retrieved on 2007-06-13. 
  8. ^ http://www.attract.wales.nhs.uk/question_answers.cfm?question_id=1889
  9. ^ http://rheumatology.oxfordjournals.org/cgi/content/full/41/11/1240
  10. ^ http://www.biochem.northwestern.edu/ibis/articles/Shea/Segura_et_al_Biomat_2004.pdf
  11. ^ http://www.biomateria.com/bio_skin_3.htm
  12. ^ Hylan G-F 20 (Synvisc) approved by EMEA for pain due to ankle and shoulder OA. National Health Service. Retrieved on 2007-07-09.
  • Auvinen P, Tammi R, Parkkinen J, Tammi M, Agren U, Johansson R, Hirvikoski P, Eskelinen M, Kosma VM. "Hyaluronan in peritumoral stroma and malignant cells associates with breast cancer spreading and predicts survival." Am J Pathol. 2000 Feb;156(2):529-36. PMID 10666382
  • Toole BP. "Hyaluronan in morphogenesis." J Intern Med. 1997 Jul;242(1):35-40. PMID 9260564
  • Medical applications of hyaluronan, from the Glycoforum
  • http://www.bioiberica.com/art_joint_prod4_syn.asp

Year 2007 (MMVII) is now the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 163rd day of the year (164th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is now the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 164th day of the year (165th in leap years) in the Gregorian calendar. ... , the information in this article describes the current English public health service. ... Year 2007 (MMVII) is now the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 190th day of the year (191st in leap years) in the Gregorian calendar. ...

External links


  Results from FactBites:
 
Hyaluronan - definition of Hyaluronan in Encyclopedia (604 words)
Hyaluronan (also called hyaluronic acid or hyaluronate) is a glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues.
Hyaluronan is energetically stable in part because of the stereochemistry of its component disaccharides.
Hyaluronan is thus often used as a tumor marker for prostate and breast cancer.
Hyaluronan - Wikipedia, the free encyclopedia (786 words)
Hyaluronan is naturally found in many tissues of the body such as skin, cartilage, and the vitreous humor.
Hyaluronan is also used to treat osteoarthritis of the knee [4][5][6].
Hyaluronan is also now a common skin care ingredient, due to its moisturizing effects.
  More results at FactBites »

 
 

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