Rosacea
Encyclopedia
Rosacea r is a chronic
Chronic (medicine)
A chronic disease is a disease or other human health condition that is persistent or long-lasting in nature. The term chronic is usually applied when the course of the disease lasts for more than three months. Common chronic diseases include asthma, cancer, diabetes and HIV/AIDS.In medicine, the...

 condition characterized by facial erythema
Erythema
Erythema is redness of the skin, caused by hyperemia of the capillaries in the lower layers of the skin. It occurs with any skin injury, infection, or inflammation...

 (redness). Pimples are sometimes included as part of the definition. Unless it affects the eyes, it is typically a harmless cosmetic condition. Treatment in the form of topical steroids can aggravate the condition.

It primarily affects Caucasians
Caucasian race
The term Caucasian race has been used to denote the general physical type of some or all of the populations of Europe, North Africa, the Horn of Africa, Western Asia , Central Asia and South Asia...

 of mainly north western European descent and has been nicknamed the 'curse of the Celts' by some in Britain and Ireland, but can also affect people of other ethnicities. Rosacea affects both sexes, but is almost three times more common in women. It has a peak age of onset between 30 and 60.

Rosacea typically begins as redness on the central face across the cheeks, nose, or forehead, but can also less commonly affect the neck, chest, ears, and scalp. In some cases, additional symptoms, such as semi-permanent redness, telangiectasia
Telangiectasia
Telangiectasias /tɛ.læn.dʒiː'ɛk.teɪ.ʃi:ə/ are small dilated blood vessels near the surface of the skin or mucous membranes, measuring between 0.5 and 1 millimeter in diameter. They can develop anywhere on the body but are commonly seen on the face around the nose, cheeks, and chin...

 (dilation of superficial blood vessels on the face), red domed papule
Papule
A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in size from a pinhead to 1 cm.With regard to the quote "...varying in size from a pinhead to 1cm," depending on which text is referenced, some authors state the cutoff between a papule and a plaque as 0.5cm,...

s (small bumps) and pustules, red gritty eyes, burning and stinging sensations, and in some advanced cases, a red lobulated nose (rhinophyma
Rhinophyma
Rhinophyma is a descriptive term for a large, bulbous, ruddy appearance of the nose caused by granulomatous infiltration, commonly due to untreated rosacea.- Causes :...

), may develop.

Classification

There are four identified rosacea subtypes and patients may have more than one subtype present:
  1. Erythematotelangiectatic rosacea: Permanent redness (erythema
    Erythema
    Erythema is redness of the skin, caused by hyperemia of the capillaries in the lower layers of the skin. It occurs with any skin injury, infection, or inflammation...

    ) with a tendency to flush
    Flushing (physiology)
    For a person to flush is to become markedly red in the face and often other areas of the skin, from various physiological conditions. Flushing is generally distinguished, despite a close physiological relation between them, from blushing, which is milder, generally restricted to the face, cheeks or...

     and blush
    Blushing
    Blushing refers to the involuntary reddening of a person's face due to embarrassment or emotional stress, though it has been known to come from being lovestruck, or from some kind of romantic stimulation. It is thought that blushing is the result of an overactive sympathetic nervous system...

     easily. It is also common to have small blood vessels visible near the surface of the skin (telangiectasias) and possibly burning or itching sensations.
  2. Papulopustular rosacea: Some permanent redness with red bumps (papule
    Papule
    A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in size from a pinhead to 1 cm.With regard to the quote "...varying in size from a pinhead to 1cm," depending on which text is referenced, some authors state the cutoff between a papule and a plaque as 0.5cm,...

    s) with some pus filled (pustules) (which typically last 1–4 days); this subtype can be easily confused with acne.
  3. Phymatous rosacea: This subtype is most commonly associated with rhinophyma
    Rhinophyma
    Rhinophyma is a descriptive term for a large, bulbous, ruddy appearance of the nose caused by granulomatous infiltration, commonly due to untreated rosacea.- Causes :...

    , an enlargement of the nose. Symptoms include thickening skin, irregular surface nodularities, and enlargement. Phymatous rosacea can also affect the chin (gnathophyma), forehead (metophyma), cheeks, eyelids (blepharophyma), and ears (otophyma). Small blood vessels visible near the surface of the skin (telangiectasias) may be present.
  4. Ocular rosacea
    Ocular rosacea
    Ocular rosacea is a manifestation of rosacea that affects the eyes and eyelids. Symptoms generally consist of redness, irritation or burning of the eyes. Patients may also feel that there is something, such as an eyelash, in the eye...

    :
    Red, dry and irritated eyes and eyelids. Some other symptoms include foreign body sensations, itching and burning.


There are a number of variants of rosacea including:
  • Rosacea conglobata
    Rosacea conglobata
    Rosacea conglobata is a severe rosacea that shows a reaction which mimics acne conglobata with hemorrhagic nodular abscesses and indurated plaques....

  • Rosacea fulminans
  • Phymas in rosacea
    Phymas in rosacea
    Phymatous rosacea is a cutaneous condition characterized by overgrowth of sebaceous glands. "Phyma" is the Greek word for swelling, mass, or bulb, and these can occur in various areas of the face and ears in associated with rosacea. Types of phyma seen in rosacea are:* Rhinophyma* Gnathophyma*...


Cause

Triggers that cause episodes of flushing and blushing play a part in the development of rosacea. Exposure to temperature extremes can cause the face to become flushed as well as strenuous exercise, heat from sunlight, severe sunburn
Sunburn
A sunburn is a burn to living tissue, such as skin, which is produced by overexposure to ultraviolet radiation, commonly from the sun's rays. Usual mild symptoms in humans and other animals include red or reddish skin that is hot to the touch, general fatigue, and mild dizziness. An excess of UV...

, stress, anxiety, cold wind, and moving to a warm or hot environment from a cold one such as heated shops and offices during the winter. There are also some food and drinks that can trigger flushing, including alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

, food and beverages containing caffeine
Caffeine
Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...

 (especially, hot tea and coffee), foods high in histamine
Histamine
Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by...

s and spicy food. Foods high in histamine (red wine, aged cheeses, yogurt, beer, cured pork products such as bacon, etc.) can even cause persistent facial flushing in those individuals without rosacea due to a separate condition, histamine intolerance.

Certain medications and topical irritants can quickly trigger rosacea. Some acne and wrinkle treatments that have been reported to cause rosacea include microdermabrasion and chemical peels, as well as high dosages of isotretinoin
Isotretinoin
Isotretinoin, INN, is a medication used mostly for cystic acne. It was first developed for brain, pancreatic and other cancers. It is used to treat harlequin-type ichthyosis, a usually lethal skin disease, and lamellar ichthyosis. Its effects are systemic and nonselective...

, benzoyl peroxide, and tretinoin
Tretinoin
Tretinoin is the acid form of vitamin A and is also known as all-trans retinoic acid or ATRA. It is a drug commonly used to treat acne vulgaris and keratosis pilaris. It is available as a cream or gel...

. Steroid
Steroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...

 induced rosacea
is the term given to rosacea caused by the use of topical or nasal steroids. These steroids are often prescribed for seborrheic dermatitis. Dosage should be slowly decreased and not immediately stopped to avoid a flare up.

A survey by the National Rosacea Society of 1,066 rosacea patients showed which factors affect the most people:
  • Sun exposure 81%
  • Emotional stress 79%
  • Hot weather 75%
  • Wind 57%
  • Heavy exercise 56%
  • Alcohol consumption 52%
  • Hot baths 51%
  • Cold weather 46%
  • Spicy foods 45%
  • Humidity 44%
  • Indoor heat 41%
  • Certain skin-care products 41%
  • Heated beverages 36%
  • Certain cosmetics 27%
  • Medications (specifically stimulants) 15%
  • Medical conditions 15%
  • Certain fruits 13%
  • Marinated meats 10%
  • Certain vegetables 9%
  • Dairy products 8%

Cathelicidins

Richard L. Gallo and colleagues recently noticed that patients with rosacea had elevated levels of the peptide cathelicidin
Cathelicidin
Members of the cathelicidin family of antimicrobial polypeptides are characterized by a highly conserved region and a highly variable cathelicidin peptide domain.Cathelicidin peptides have been isolated from many different species of mammals...

 and elevated levels of stratum corneum
Stratum corneum
The stratum corneum is the outermost layer of the epidermis, consisting of dead cells that lack nuclei and organelles. The purpose of the stratum corneum is to form a barrier to protect underlying tissue from infection, dehydration, chemicals and mechanical stress...

 tryptic enzymes (SCTEs). Antibiotics have been used in the past to treat rosacea but they may only work because they inhibit some SCTEs.

Intestinal bacteria

Intestinal bacteria may play a role in causing the disease. A recent study subjected patients to a hydrogen breath test
Hydrogen Breath Test
A hydrogen breath test is used as a clinical medical diagnosis for people with irritable bowel syndrome, and common food intolerances. The test is simple, non-invasive, and is performed after a short period of fasting . Even though the test is normally known as a "Hydrogen Breath Test" some...

 to detect the occurrence of small intestinal bacterial overgrowth
Small bowel bacterial overgrowth syndrome
Small bowel bacterial overgrowth syndrome , or small intestinal bacterial overgrowth , also termed bacterial overgrowth; is a disorder of excessive bacterial growth in the small intestine. Unlike the colon , which is rich with bacteria, the small bowel usually has less than 104 organisms per...

 (SIBO). It was found that significantly more patients were hydrogen-positive than controls indicating the presence of bacterial overgrowth (47% v. 5%, p<0.001).

Hydrogen-positive patients were then given a 10-day course of rifaximin, a non-absorbable antibiotic that does not leave the digestive tract and therefore does not enter the circulation or reach the skin. 96% of patients experienced a complete remission of rosacea symptoms that lasted beyond 9 months. These patients were also negative when retested for bacterial overgrowth. In the 4% of patients that experienced relapse, it was found that bacterial overgrowth had returned. These patients were given a second course of rifaximin which again cleared rosacea symptoms and normalized hydrogen excretion.

In another study, it was found that some rosacea patients that tested hydrogen-negative were still positive for bacterial overgrowth when using a methane breath test
Hydrogen Breath Test
A hydrogen breath test is used as a clinical medical diagnosis for people with irritable bowel syndrome, and common food intolerances. The test is simple, non-invasive, and is performed after a short period of fasting . Even though the test is normally known as a "Hydrogen Breath Test" some...

 instead. These patients showed little improvement with rifaximin, as found in the previous study, but experienced clearance of rosacea symptoms and normalization of methane excretion following administration of the antibiotic metronidazole
Metronidazole
Metronidazole is a nitroimidazole antibiotic medication used particularly for anaerobic bacteria and protozoa. Metronidazole is an antibiotic, amebicide, and antiprotozoal....

, which is effective at targeting methanogenic intestinal bacteria.

These results suggest that optimal antibiotic therapy may vary between patients and that diverse species of intestinal bacteria appear to be capable of mediating rosacea symptoms.

This may also explain the improvement in symptoms experienced by some patients when given a reduced carbohydrate diet. Such a diet would restrict the available material necessary for bacterial fermentation
Fermentation (food)
Fermentation in food processing typically is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. Fermentation in simple terms is the chemical conversion of sugars into ethanol...

 and thereby reduce intestinal bacterial populations.

Demodex mites

Studies of rosacea and demodex mite
Demodex mite
Demodex is a genus of tiny parasitic mites that live in or near hair follicles of mammals. About 65 species of Demodex are known; they are among the smallest of arthropods. Two species living on humans have been identified: Demodex folliculorum and Demodex brevis, both frequently referred to as...

s have revealed that some people with Rosacea have increased numbers of the mite, especially those with steroid induced rosacea. When large numbers are present they may play a role along with other triggers. On other occasions demodicidosis
Mange
Mange is the common name for a class of persistent contagious skin diseases caused by parasitic mites. Since mites also infect plants, birds, and reptiles, the term "mange," suggesting poor condition of the hairy coat due to the infection, is sometimes reserved only for pathological...

 (mange) is a separate condition that may have "rosacea-like" appearances.

Diagnosis

Most people with rosacea have only mild redness and are never formally diagnosed or treated. There is no single, specific test for rosacea.

In many cases, simple visual inspection by a trained person is sufficient for diagnosis. In other cases, particularly when pimples or redness on less-common parts of the face are present, a trial of common treatments is useful for confirming a suspected diagnosis.

The disorder can be confused with, and co-exist with acne vulgaris
Acne vulgaris
Acne vulgaris is a common human skin disease, characterized by areas of skin with seborrhea , comedones , papules , pustules , Nodules and possibly scarring...

 and/or seborrhoeic dermatitis
Seborrhoeic dermatitis
Seborrhoeic dermatitis is an inflammatory skin disorder affecting the scalp, face, and torso. Typically, seborrheic dermatitis presents with scaly, flaky, itchy, and red skin. It particularly affects the sebaceous-gland-rich areas of skin...

. The presence of rash on the scalp or ears suggests a different or co-existing diagnosis as rosacea is primarily a facial diagnosis, although it may occasionally appear in these other areas.

Treatments

Treating rosacea varies depending on severity and subtypes. A subtype-directed approach to treating rosacea patients is recommended to dermatologists. Mild cases are often not treated at all, or are simply covered up with normal cosmetics
Foundation (cosmetics)
Foundation is a skin coloured cosmetic applied to the face to create an even, uniform colour to the complexion, to cover flaws, and, sometimes, to change the natural skintone. Foundation applied to the body is generally referred to as "body painting"....

.
Therapy for the treatment of rosacea is not curative, and is best measured in terms of reduction in the amount of erythema and inflammatory lesions, decrease in the number, duration, and intensity of flares, and concomitant symptoms of itching, burning, and tenderness. The two primary modalities of rosacea treatment are topical and oral antibiotic agents.
While medications often produce a temporary remission of redness within a few weeks, the redness typically returns shortly after treatment is suspended. Long-term treatment, usually one to two years, may result in permanent control of the condition for some patients. Lifelong treatment is often necessary, although some cases resolve after a while and go into a permanent remission.

Behaviour

Trigger avoidance can help reduce the onset of rosacea but alone will not normally cause remission for all but mild cases. It is sometimes recommended that a journal be kept to help identify and reduce food and beverage triggers.

Because sunlight is a common trigger, avoiding excessive exposure to sun is widely recommended. Some people with rosacea benefit from daily use of a sunscreen
Sunscreen
Sunblock is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet radiation on the skin exposed to sunlight and thus helps protect against sunburn...

; others opt for wearing hats with broad brims.

People who develop infections of the eyelids must practice frequent eyelid hygiene. Daily, gentle cleansing of the eyelids with diluted baby shampoo or an over-the-counter eyelid cleaner and applying warm (but not hot) compresses several times a day is recommended.

A recent publication discusses how managing pre-trigger events such as prolonged exposure to cool environments can directly influence warm room flushing.

Medications

Oral tetracycline antibiotics
Tetracycline antibiotics
Tetracyclines are a group of broad-spectrum antibiotics whose general usefulness has been reduced with the onset of bacterial resistance. Despite this, they remain the treatment of choice for some specific indications....

 (tetracycline, doxycycline
Doxycycline
Doxycycline INN is a member of the tetracycline antibiotics group, and is commonly used to treat a variety of infections. Doxycycline is a semisynthetic tetracycline invented and clinically developed in the early 1960s by Pfizer Inc. and marketed under the brand name Vibramycin. Vibramycin...

, minocycline
Minocycline
Minocycline is a broad-spectrum tetracycline antibiotic, and has a broader spectrum than the other members of the group. It is a bacteriostatic antibiotic, classified as a long-acting type...

) and topical antibiotics such as metronidazole
Metronidazole
Metronidazole is a nitroimidazole antibiotic medication used particularly for anaerobic bacteria and protozoa. Metronidazole is an antibiotic, amebicide, and antiprotozoal....

 are usually the first line of defense prescribed by doctors to relieve papules, pustules, inflammation and some redness. Topical azelaic acid
Azelaic acid
Azelaic acid is an organic compound with the formula 72. This saturated dicarboxylic acid exists as a white powder. It is found in wheat, rye, and barley. It is a component of a number of hair and skin conditioners.-Production:...

 such as Finacea (15%) or Skinoren (20%) may help reduce inflammatory lesions, bumps and papules. Using alpha-hydroxy acid peels may help relieve redness caused by irritation, and reduce papules and pustules associated with rosacea. Oral antibiotics may help to relieve symptoms of ocular rosacea. If papules and pustules persist, then sometimes isotretinoin
Isotretinoin
Isotretinoin, INN, is a medication used mostly for cystic acne. It was first developed for brain, pancreatic and other cancers. It is used to treat harlequin-type ichthyosis, a usually lethal skin disease, and lamellar ichthyosis. Its effects are systemic and nonselective...

 can be prescribed. Isotretinoin has many side effects and is normally used to treat severe acne but in low dosages is proven to be effective against papulopustular and phymatous rosacea.

The treatment of flushing and blushing has been attempted by means of the centrally acting α-2 agonist clonidine
Clonidine
Clonidine is a sympatholytic medication used to treat medical conditions, such as high blood pressure, some pain conditions, ADHD and anxiety/panic disorder...

, but this is of limited benefit on just this one aspect of the disorder. The same is true of the beta-blockers nadolol and propranolol. If flushing occurs with red wine consumption, then complete avoidance helps. There is no evidence at all that antihistamines are of any benefit in rosacea. However: people with underlying allergies and who respond strongly to foods that are high in histamine or that release a lot of histamine in the body do find sometimes that their flushing symptoms diminish with oral antihistamines (for instance loratadine).
Another medication that can help some people with facial flushing and burning is mirtazapine (remeron).

Recently, a clinically-trialled product range combining plant-sourced methylsulfonylmethane
Methylsulfonylmethane
Methylsulfonylmethane is an organosulfur compound with the formula 2SO2. It is also known by several other names including DMSO2, methyl sulfone, and dimethyl sulfone. This colorless solid features the sulfonyl functional group and is considered relatively inert chemically...

 (MSM) and silymarin has been used to treat rosacea, skin redness and flushing.

Laser

Dermatological vascular laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

 (single wavelength) or intense pulsed light
Intense pulsed light
Intense pulsed light , is a technology aimed at producing light of high intensity during a very short period of time. It involves specific lamps together with capacitors whose rapid discharge provides the high energy required....

 (broad spectrum) machines offer one of the best treatments for rosacea, in particular the erythema
Erythema
Erythema is redness of the skin, caused by hyperemia of the capillaries in the lower layers of the skin. It occurs with any skin injury, infection, or inflammation...

 (redness) of the skin. They use light to penetrate the epidermis to target the capillaries in the dermis
Dermis
The dermis is a layer of skin between the epidermis and subcutaneous tissues, and is composed of two layers, the papillary and reticular dermis...

 layer of the skin. The light is absorbed by oxy-hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...

 which heat up causing the capillary walls to heat up to 70 °C (158 °F) , damaging them, causing them to be absorbed by the body's natural defense mechanism. With a sufficient number of treatments, this method may even eliminate the redness altogether, though additional periodic treatments will likely be necessary to remove newly-formed capillaries.

CO2 laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

s can be used to remove excess tissue caused by phymatous rosacea. CO2 lasers emit a wavelength that is absorbed directly by the skin. The laser beam can be focused into a thin beam and used as a scalpel or defocused and used to vaporise tissue. Low level light therapies have also been used to treat rosacea.
Photorejuvenation
Photorejuvenation
Photorejuvenation is a skin treatment that uses intense pulsed light or other thermal or chemical methods to treat some skin conditions and remove wrinkles arising from photoaging. The process induces controlled wounds on the skin, prompting it to heal itself by creating new cells...

 can also be used to improve the appearance of rosacea and reduce the redness associated with it.

Notable cases

Famous people with rosacea include:
  • Bill Clinton
    Bill Clinton
    William Jefferson "Bill" Clinton is an American politician who served as the 42nd President of the United States from 1993 to 2001. Inaugurated at age 46, he was the third-youngest president. He took office at the end of the Cold War, and was the first president of the baby boomer generation...

  • Alex Ferguson
    Alex Ferguson
    Sir Alexander Chapman "Alex" Ferguson, CBE is a Scottish association football manager and former player, currently managing Manchester United, where he has been in charge since 1986...

  • J. P. Morgan
    J. P. Morgan
    John Pierpont Morgan was an American financier, banker and art collector who dominated corporate finance and industrial consolidation during his time. In 1892 Morgan arranged the merger of Edison General Electric and Thomson-Houston Electric Company to form General Electric...

  • Meg Cabot
    Meg Cabot
    Meg Cabot is anAmerican author of romantic and paranormal fiction for teens and adults and used to write under several pen names, but now writes exclusively under her real name, Meg Cabot...

  • W. C. Fields
    W. C. Fields
    William Claude Dukenfield , better known as W. C. Fields, was an American comedian, actor, juggler and writer...

  • Rosie O'Donnell
    Rosie O'Donnell
    Roseann "Rosie" O'Donnell is an American stand-up comedian, actress, author and television personality. She has also been a magazine editor and continues to be a celebrity blogger, LGBT rights activist, television producer and collaborative partner in the LGBT family vacation company R Family...

  • Mariah Carey
    Mariah Carey
    Mariah Carey is an American singer-songwriter, record producer, and actress. She made her recording debut with the release of her eponymous studio album in 1990, under the guidance of Columbia Records executive Tommy Mottola, whom she later married in 1993...

  • Margaret Bobonich
  • Ricky Wilson
    Ricky Wilson (British musician)
    Ricky Wilson is the lead singer of English band Kaiser Chiefs. Wilson has also been on the panel of the BBC Television comedy series Shooting Stars in 2009, Never Mind the Buzzcocks in 2005, and was a guest host on the show in 2006.-Character and Style:Wilson is well known for wearing stripy...

  • Lisa Faulkner
    Lisa Faulkner
    Lisa Tamsin Faulkner is an English actress and television personality.-Early life:Faulkner was educated at Tiffin Girls' School, Kingston upon Thames.When Faulkner was 16, her mother, Julie, died of cancer...

  • Dita Von Teese
    Dita Von Teese
    Dita Von Teese is an American burlesque dancer, model, costume designer, author and actress.-Early life:...

  • Carol Smillie
    Carol Smillie
    Carol Patricia Smillie is a Scottish television personality, model and actress. Smillie is well-known for presenting the award winning BBC series Changing Rooms, which won her a National Television Award for Most Popular Factual Programme in 1998.She became the hostess of the British version of...


See also

  • Keratosis pilaris
    Keratosis pilaris
    Keratosis pilaris is a common, autosomal dominant, genetic follicular condition that is manifested by the appearance of rough bumps on the skin...

  • Demodicosis
    Demodicosis
    Demodicosis, also called demodectic mange or red mange, is caused by a sensitivity to and overpopulation of Demodex canis as the animal's immune system is unable to keep the mites under control....

     a rash caused by the Demodex mite
    Demodex mite
    Demodex is a genus of tiny parasitic mites that live in or near hair follicles of mammals. About 65 species of Demodex are known; they are among the smallest of arthropods. Two species living on humans have been identified: Demodex folliculorum and Demodex brevis, both frequently referred to as...

    that may have rosacea-like appearances.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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