Rides et acide hyaluronique
Hyaluronic acid (from Greek = hyalos glassy uronic because it was first isolated from the vitreous humor and has a high level of uronic acid) is a glycosaminoglycan distributed widely among tissues, epithelial and nervous. One finds, for example, in vitreous humor and synovial fluid. This is one of the main components of the extracellular matrix. It contributes significantly to the proliferation and cell migration. There may be implicated in the progression of certain malignancies.
It is associated with a protein fraction to form a mucoprotein.
References
In aesthetic medicine, hyaluronic acid is indicated for filling lines and wrinkles of the face and neck. In addition to this form, see our file ‘Erase wrinkles with hyaluronic acid,’ with the testimony of a patient in whom it works! What is hyaluronic acid? Hyaluronic acid is normally a natural constituent of the body and especially of the skin (but also the joints).It contributes to the hydration of the skin by attracting water. In aesthetic medicine, hyaluronic acid is now used as an alternative to collagen, with – among others – the advantage of less risk of allergy.
Over 90% of UV-B are stopped by the skin of which 70% of the stratum corneum only. The epidermis is also an obstacle to UV A but 20% of them still come to the dermis. This small percentage is enough to cause significant biological effects. The ultraviolet rays act on different cellular components: proteins, nucleic acids, membranes … They strike the blood capillaries and fibroblasts. UVB induces the formation of dimers in DNA chains. These phenomena are blocking the translation of genetic information and prevent cellular repair of such damage. This leads to metabolic defects (aging) and eventually cell death or acquisition of properties of disordered proliferation (cancer). All these problems are aggravated by the release of free radicals in the cell membranes.
Free radicals have taken in recent years a great importance in explaining many biological processes. They may be regarded as a waste of cell metabolism.
Ionizing radiation (X rays and gamma rays) are so energetic that they can break water molecules (H2O), breaking the bond between hydrogen and oxygen, producing a free radical hydroxyl (OH) very reactive.
Ultraviolet rays are ionizing radiation and may destroy the water molecules. By cons, they can be absorbed by some biological molecules. This energy absorption causes excitation of electrons of the biological molecule. If the photon is energetic enough, an electron device is torn and there is creation of a free radical highly reactive. The oxygen in the vicinity which has two electrons tends to make one of its two electrons to replace the electron torn. The molecule is then transformed into a peroxide derivative whose biological activity can be totally different from the original molecule.
In other cases, the molecule that absorbed photons is taken to a higher energy state. This energy is transmitted to the oxygen that becomes a highly activated oxygen oxidant. These atoms and these molecules have a high energy destroy what they encountered before being neutralized. Different biological molecules (unsaturated fatty acids in cell membranes, proteins, collagen microfibrils, amino acids, lipids, hyaluronic acid, DNA chromosome …) can be oxidized and lead to other free radicals in the reaction sequence chain.
The alteration of biological molecules leads to loss of physiological functions. Transformations caused to DNA pose the risk of cancer.
There are molecules that can trap free radicals, breaking the chain reaction of free radical molecules and protect it is by example the case of provitamin A, antioxidant vitamins C and E, zinc, selenium, or carotenoids.
Skin aging is characterized by the appearance of signs or lesions that did not exist previously. The most common and earliest are the spots of color lighter or darker appearing on the backs of the hands and face. Called ‘graveyard flowers’ or ‘age spots’, these are small plates without relief where the color is different from the rest of the skin. They simply reflect the overproduction of melanocytes pecked in the epidermis. In other words, in some places, the melanocytes begin to function much more for reasons unknown. Other lesions appear colored and embossed on the back and chest mainly. Their surface resembles a cauliflower. It’s ‘seborrheic’ with no gravity, but are sometimes confused with more serious lesions (melanoma). AKs are different. These are localized thickening of the skin flakes off. If the patient tries to tear these scales, a little bleeding occurs. These lesions, which are considered precancerous, are on sun-exposed areas:face and backs of hands. Aging skin is still responsible for purpura and pseudo-scars. The thinning of the skin with age is another stigma of aging that has atrophy of the dermis and epidermis. Itching, dryness, wrinkles are other symptoms of normal aging.
The sun aggravates and accelerates the onset of these symptoms. Premature skin aging is indeed the first chronic effect of overexposure to the sun. It occurs 10 or 20 years after irradiation.
The ultraviolet rays act on cells of the skin and break the chains of DNA that are permanently corrected by repair enzymes. If this mechanism is overwhelmed by prolonged exposure, the cells of the basal layer, which provide skin renewal are met. Their production of melanin, collagen and elastin decreases: it is solar elastosis.
Dry skin, wrinkles more pronounced, loss of elasticity, pigmentation (solar lentigines), purpura, telangiectasia, epidermal atrophy and dehydration are all hallmarks of aging.
The depletion of tissue, especially if it is associated with weight loss after a phase of obesity, causes jowls, sagging eyelids …
The excessive tanning accelerates skin aging. This is not only detrimental to the aesthetics. Promotes premature skin aging and skin irritation reactions to medications while decreasing the rate of healing.
No drug prevents skin aging. The only treatment is prevention and is based on adopting a healthy lifestyle on all fronts: food, sunshine, sleep, smoking, alcohol … Avoiding excess sun and changes in weight, it already limits the damage. If properly applied sun protection are useful for preventing premature skin aging, interest in other products is illusory.
The anti-wrinkle cosmetics are designed to improve hydration of the stratum corneum and the film quality hydrolipidic surface while increasing the thickness of the epidermis.They try to stimulate fibroblasts in their synthesis of collagen, elastin, proteoglycans and glycoproteins. Among the products used, hyaluronic acid and elastin of great interest to cosmetologists. The effectiveness of collagen in the preparation has not been demonstrated. The unsaponifiables and soybean lawyer, placental extracts (embryonic or amniotic), evening primrose oil, argan oil, silicon components are part of the ‘anti-wrinkle creams’ that act more by a fill and hydrating the skin as an effect ‘refreshing’ in the dermis, which remains highly uncertain.
The use of vitamin A in the prevention of aging skin has been much ink. Treatment should be indefinite because aging is a permanent phenomenon. A moisturizer should be used together because vitamin A acid causes dryness and scaling at the beginning of treatment. Locally, vitamin A acid is equivalent to a gentle peeling:she gently exfoliating skin hence its efficacy in acne (ABEREL, Effederm, Locacid, Retacnyl, Tretinoin Kefran etc.).
Vitamin A acid erase superficial wrinkles but some improvement is slow and inconsistent and involves only superficial wrinkles. There is no action on sagging cheeks and chin. Vitamin A acid has no authorization in the market (AMM) in the prevention of skin aging. In fact, the cosmetic action of vitamin A acid is modest and at the cost of skin irritation.
The many synthetic retinoids have emerged since 1968, only two are marketed: isotretinoin (Roaccutane) in acne prescribed nodulocystic and etretinate (Soriatane) is used in some psoriasis and keratinization disorders. Since vitamin A acid, none has received approval of social security in the indication of prevention of skin aging.
Proponents of natural medicine offer recipes for slowing premature aging.Found vitamin A as beta-carotene (melons, tomatoes, carrots, fresh apricots …), as well as vitamin E (calf liver, whole wheat bread, corn, rice, oil olive oil soy …), vitamin C, selenium and SOD (enzyme superoxide dismutase content especially in the skins of grapes, and seaweed salad) that trap and neutralize free radicals. Based local care including macadamia nut oil are also recommended by some.
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Structure
The chemical structure of acid hyalobiuronique was determined in 1930 in the laboratory of Karl Meyer. Hyaluronic acid is a polymer of disaccharides, themselves composed of D-glucuronic acid and DN-acetylglucosamine, linked together by glycosidic bonds alternating beta-1, 4 and beta-1, 3. The polymers of this repeating unit may have a size between 10 m² and 104 kDa in vivo.
Hyaluronic acid is stable in terms of energy, partly because of the stereochemical aspects of its component disaccharides.
Medical Applications
Hyaluronic acid is naturally present in various body tissues such as skin, cartilage. It is therefore suitable for biomedical applications targeting these tissues. The first biomedical product based on hyaluronic acid, Healon, was developed in the 1970s and approved for use in ophthalmic surgery (ie, corneal transplantation, cataract, glaucoma, etc.)..
Hyaluronic acid is also used to treat osteoarthritis of the knee. Such treatments are administered as injections such qu’Ostenil (TRB Chemedica) in the knee joint to increase the viscosity of synovial fluid and thus lubricate the joint.
In recent years, it is used in cosmetic medicine such as filler for wrinkles. Products based on hyaluronic acid such as Restylane (Q-Med Laboratories) or Surgiderm (Lab Cornéal) are used by doctors to replace collagen as hyaluronic acid reduces the risk of allergies and lasts longer (6 to 12 months). Moreover, its definitive resorbability prevents accidents.
In some cancers, hyaluronic acid levels are fairly well correlated with the malignancy with a poor prognosis. Therefore, hyaluronic acid is often used as a tumor marker for prostate cancer and breast. It can also be used to monitor disease progression.
It can also be used in postoperative care to promote the recovery of tissues, mostly after a cataract operation.
Hyaluronic acid is now commonly used as an ingredient in cosmetics due to its moisturizing properties. Plus it tends to be increasingly used in cosmetic surgery for soft tissue augmentation and in particular in the filling of wrinkles.
Summary
Hyaluronic acid consists of about 5000 units dissacharidic, it is the size of a bacterium and has an appearance of frost.
SKIN
Body which covers the surface of the body. It has a surface layer called the epidermis and dermis that covers a deeper layer, the hypodermis, which contains the adipose tissue.Annexes are dander (hair, nails) and glands: sebaceous and sweat glands.
It is elastic and has many nerve endings that allow the sense of touch (pressure, temperature, shape).
The skin may be normal, oily or dry.
– Normal skin, perfect somehow occurs in children before puberty. Some women retain this ideal skin during their lifetime: the peach complexion, greatly envied, however, makes the skin sensitive skin: it turns brown and is often difficult to seat ROSACEA.
– Oily skin: it has a grainy look, irregular, because the pilosebaceous orifices are dilated. These skins can be dehydrated because of physical, chemical or drug (wind, sun detergent, for example).
– Dry skin: it is dry by default hydration and insufficient sebum secretion by due to a keratinization disorder or aging.
TREATMENT:
– Oily skin:They stand up well to water and soap, but it should not be too much detergent: the soap is not recommended.
It may be useful to use cleansing milk for oily skin (rinse after application).
Some masks absorb excess sebum making the skin less shiny (they are made from kaolin clay, for example).
For oily skin dehydrated, we could make use of emulsion. An emulsion consists of two non miscible one of which is finely dispersed in the other. One product is a dispersant, the other dispersible. If the dispersant is watery and oily dispersible product, the emulsion is recommended for oily skin. Otherwise, the emulsion is for dry skin.
– Dry skin: This skin resent the soap.
We must use soaps surgras, milks and emulsions which leave a greasy film on the skin after use, allowing water retention in the basal layer of the skin. These emulsions must submit a dispersant and oil dispersible aqueous.
– Skin Aging:These are dry skin.
The sebaceous secretion is decreased.
The use of special emulsions for dry skin is recommended.
Creams containing collagen, elastin, hyaluronic acid, can temporarily tighten the skin.
Others based on extracts from plants (soy, avocado), embryonic extracts (placenta) or vitamins, are trying to delay the aging of the skin.
Remember that the sun is an important factor in aging of the skin. Similarly tobacco promote accelerated aging of the skin, especially if combined with the effect of the sun.
We must reiterate the fact quite harmful to the face of prolonged exposure to sunlight, causes early onset of wrinkles.
See RIDES.