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Hyalgan

Hyaluronan (also called hyaluronic acid or hyaluronate) is a 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. more...

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Functions

Until the late 1970s, hyaluronan was described as a "goo" molecule, a ubiquitous carbohydrate polymer that comprised the extracellular matrix. For example, hyaluronan is a major component of the extracellular matrix that constitutes synovial fluid. Along with lubricin, it is one of the fluid's main lubricating components. It helps protect joints by increasing the viscosity of the fluid and by making the cartilage between bones more elastic.

While it is found in large numbers 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 in vivo, 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, the chief in vivo hyaluronan receptor, participates in cell adhesion interactions required by tumor cells. Some of the enzymes that break down hyaluronan are known tumor suppressants; paradoxically, the gene for hyaluronidase-2 is an oncogene and promotes tumor growth.

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 beta-1,4 and beta-1,3 glycosidic bonds. Polymers of hyaluronan can range in size from 102 to 104 kDa in vivo.

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.

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.

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.

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 ophthalmic surgery (i.e. corneal transplantation, cataract surgery, glaucoma surgery and retinal attachment surgery). Other biomedical companies also produce brands of hyaluronan for ophthalmic surgery .

Read more at Wikipedia.org


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Work can be a pain in the back...and in the hip, knee, elbow, and shoulder
From Electrical Apparatus, 8/1/02 by Elsberry, Richard B

Safety and health

As workers get older, injury risks increase

LOWER BACK PAIN MAY BE responsible for more lost workdays than any other occupational injury with the possible exception of repetitive stress damage to the wrist and hand.

An aging work force, however, also is experiencing significant increases in debilitating hip, knee, elbow, and shoulder damage, as well as hard-to-- treat, slow-to-heal injuries to leg and foot muscles. Such physical impairments are becoming particularly prevalent among those entering their fourth decade in the job mart.

The resultant chronic joint and muscle pain that is sidelining older employees is not a result of on-the-job accidents but rather stems primarily from wear and tear on the human body due to overuse, general deterioration of the human frame over time, and the onset of degenerative diseases such as osteoarthritis.

Worn-out cartilage

An estimated 21 million Americans are afflicted with osteoarthritis, which attacks and destroys cartilage. Cartilage is a flexible, rubber-like substance attached to the ends of bones that make up movable joints, such as the rotator cuff that connects the arm to the shoulder blade, and cushions their interaction. As this connective tissue wears away and is not replaced, bone begins to rub against bone, and the resulting abrasion can produce intense pain.

Osteoarthritis generally begins to affect the ability to manipulate joints when a person reaches his 60th birthday, but it increasingly is turning up in athletically active persons in their 50's.

How joint pain is treated today generally depends on its severity and the age of the patient. Most orthopedists try, whenever possible, to delay performing surgery until around age 65. The main reason for that has been that a replacement hip or knee wears out after about 20 years, and by deferring the procedure as long as possible surgeons hope they will be able to avoid repeating it on a frail, brittle-boned, nursing home patient.

However, this time frame may soon change, as replacement knees using oxidized zirconium ceramics are now available that have an estimated life of 30 to 35 years, which may make replacement hips and knees available to patients as young as age 50.

Currently about 300,000 knee replacements and 150,000 hip replacements are done annually. The former costs about $7,000 and the latter ranges from $20,000 to $50,000.

Newer treatments

When joint pain has progressed to a point where a patient no longer wants to grit it out with aspirin, ibuprofen, naproxen, or other anti-inflammatory drugs, but goes to a physician seeking more lasting relief, orthopedists often recommend the use of two dietary supplements-glucosamine and chondroitin sulfate. These are basic building blocks of cartilage that also have anti-inflammatory properties.

Numerous studies have shown that glucosamine and chondroitin retard cartilage loss and alleviate pain. Another pain reliever getting a lot of hype is OPC (short for oligomeric proanthocyanidins), an herbal supplement with a European following targeted at those who believe in magic bullets.

To treat moderately severe osteoarthritis of the knee, some physicians have been periodically prescribing vasco-supplementation, which gives the affected joint a "lube job" by injecting it with a viscous fluid such as Synvisc, Hyalgan, or Supartz. These pain relievers have not as yet been approved for treating osteoarthritis of the hip.

Muscle injuries are among the most difficult to treat and can linger for months. Physical therapy is often ineffective. But ice packs and rest generally will, in time, enable the body to restore its normal range of motion.

Other procedures available to help pain sufferers gain relief are spinal cord stimulators, therapeutic ultrasound, cryoanalgesia, and acupuncture. Spinal cord stimulators are implanted devices that stimulate the release of pain-killing endorphins to mask pain. Ultrasound devices use sound waves to heal, providing a steady stream of energy to heat an injury. Radio frequency devices are used to destroy a nerve by burning through it, disrupting its connection to the brain. Cyroanalgesia uses extreme cold rather than heat to accomplish the same outcome. Implanted or external infusion pumps also can be used to deliver a continuous stream of painkillers to the source of the pain. Acupuncture is an ancient Chinese technique that provides short term pain relief through the placement and stimulation of fine needles at specific bodily points.

For more information:

* Healing Joint Pain Naturally, by Ellen H. Brown, Broadway Books, 1540 Broadway, New York, N.Y. 10036; (212) 782-- 9000; $12.95.

* Joint Pains, by Penelope Ody, Souvenir Press. Distributed in the U.S. by Independent Publishers Press, 814 N. Franklin St., Chicago, Ill. 60610; (800) 888-4741; $11.95.

* American Pain Foundation, No. 2700, 111 South Calvert St., Baltimore, Md. 21202; (888) 615-7246; www.painfoundation.org.

* The American Chronic Pain Association, PO. Box 850, Rocklin, Calif. 95677; (800) 533-3231; www.theacpa.org.

* American Pain Society, 4700 W. Lake Ave., Glenview, Ill. 60025; (847) 375-- 4715; www.ampainsoc.org.

By Richard B. Elsberry, EA Contributing Editor

Copyright Barks Publications Aug 2002
Provided by ProQuest Information and Learning Company. All rights Reserved

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