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Skin Whitening
Skin whitening, also known as skin lightening and skin bleaching, is the practice of using chemical substances in an attempt to lighten the skin or provide an even skin color by reducing the melanin concentration in the skin. Several chemicals have been shown to be effective in skin whitening, while some have proven to be toxic or have questionable safety profiles. This includes mercury compounds which may cause neurological problems and kidney problems. In a number of African countries, between 25 and 80% of women regularly use skin whitening products. In Asia, this number is around 40%. In India, specifically, over half of skin care products are sold to whiten skin. In Pakistan, where skin lightening products are popular, creams have been found to contain toxic levels of hydroquinone and mercury. Efforts to lighten the skin date back to at least the 1500s in Asia. While a number of agents—such as kojic acid and alpha hydroxy acid—are allowed in cosmetics in Europe, a numb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanin
Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization. The melanin pigments are produced in a specialized group of cells known as melanocytes. Functionally, eumelanin serves as protection against Ultraviolet, UV radiation. There are five basic types of melanin: eumelanin, pheomelanin, neuromelanin, allomelanin and pyomelanin. The most common type is eumelanin, of which there are two types— brown eumelanin and black eumelanin. Pheomelanin, which is produced when melanocytes are malfunctioning due to derivation of the gene to its recessive format is a cysteine-derivative that contains polybenzothiazine portions that are largely responsible for the of red yellow tint given to some skin or hair colors. Neuromelanin is found in the brain. Research ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Hydroxy Acid
α-Hydroxy acids, or alpha hydroxy acids (AHAs), are a class of chemical compounds that consist of a carboxylic acid with a hydroxyl group substituent on the adjacent (alpha) carbon. Prominent examples are glycolic acid, lactic acid, mandelic acid and citric acid. Although these compounds are related to the ordinary carboxylic acids and are therefore weak acids, their chemical structure allows for the formation of an internal hydrogen bond between the hydrogen at the hydroxyl group and one of the oxygen atoms of the carboxylic group. The net effect is an increase in acidity. For example, the pKa of lactic acid is 3.86, while that of the unsubstituted propionic acid is 4.87; a full pKa unit difference means that lactic acid is ten times stronger than propionic acid. Industrial applications Feed additives 2-Hydroxy-4-(methylthio)butyric acid is produced commercially as a racemic mixture to substitute for methionine in animal feed. In nature, the same compound is an intermediat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squamous Cell Carcinoma
Squamous-cell carcinomas (SCCs), also known as epidermoid carcinomas, comprise a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on the lining of the respiratory and digestive tracts. Common types include: * Squamous-cell skin cancer: A type of skin cancer * Squamous-cell carcinoma of the lung: A type of lung cancer * Squamous-cell thyroid carcinoma: A type of thyroid cancer * Esophageal squamous-cell carcinoma: A type of esophageal cancer * Squamous-cell carcinoma of the vagina: A type of vaginal cancer Despite sharing the name "squamous-cell carcinoma", the SCCs of different body sites can show differences in their presented symptoms, natural history, prognosis, and response to treatment. By body location Human papillomavirus infection has been associated with SCCs of the oropharynx, lung, fingers, and anogenital region. Head and neck cancer About 90% of cases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contact Dermatitis
Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes are not contagious or life-threatening, but can be very uncomfortable. Contact dermatitis results from either exposure to allergens (allergic contact dermatitis), or irritants (irritant contact dermatitis). Allergic contact dermatitis involves a delayed type of hypersensitivity and previous exposure to an allergen to produce a reaction. Irritant contact dermatitis is the most common type and represents 80% of all cases. It is caused by prolonged exposure to irritants, leading to direct injury of the epidermal cells of the skin, which activates an immune response, resulting in an inflammatory cutaneous reaction. Phototoxic dermatitis occurs when the allergen or irritant is activated by sunlight. Diagnosis of allergic contact dermatitis can o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depigmentation
Depigmentation is the lightening of the skin or loss of pigment. Depigmentation of the skin can be caused by a number of local and systemic conditions. The pigment loss can be partial (injury to the skin) or complete (caused by vitiligo). It can be temporary (from tinea versicolor) or permanent (from albinism). Most commonly, depigmentation of the skin is linked to people born with vitiligo, which produces differing areas of light and dark skin. Monobenzone also causes skin depigmentation. Increasingly, people who are not afflicted with vitiligo experiment with lower concentrations of monobenzone creams in the hope of lightening their skin tone evenly. An alternate method of lightening is to use the chemical mequinol over an extended period of time. Both monobenzone and mequinol produce dramatic skin whitening, but react very differently. Mequinol leaves the skin looking extremely pale. However, tanning is still possible. It is important to notice that the skin will not go ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cataract
A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing faces. Poor vision caused by cataracts may also result in an increased risk of falling and depression. Cataracts cause 51% of all cases of blindness and 33% of visual impairment worldwide. Cataracts are most commonly due to aging but may also occur due to trauma or radiation exposure, be present from birth, or occur following eye surgery for other problems. Risk factors include diabetes, longstanding use of corticosteroid medication, smoking tobacco, prolonged exposure to sunlight, and alcohol. The underlying mechanism involves accumulation of clumps of protein or yellow-brown pigment in the lens that reduces transmission of li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ochronosis
Ochronosis is a syndrome caused by the accumulation of homogentisic acid in connective tissues. The condition was named after the yellowish (ocher-like) discoloration of the tissue seen on microscopic examination. Macroscopically, though, the affected tissues appear bluish-grey because of a light-scattering phenomenon known as the Tyndall effect. The condition is most often associated with alkaptonuria, but can occur from exogenous administration of phenol complex (chemistry), complexes such as hydroquinone. It was first described by Rudolf Virchow in 1865.Findlay GH, et al. Ochronosis. Clinics in Dermatology 1989;7:28-35 Types The two types of ochronosis are endogenous and exogenous. The endogenous variety is an autosomal-recessive disease, known as alkaptonuria, that is caused by a lack of homogentisate oxidase enzyme.Charlín, R., Barcaui, C. B., Kac, B. K., Soares, D. B., Rabello-Fonseca, R. and Azulay-Abulafia, L. (2008), Hydroquinone-induced exogenous ochronosis: a report ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pneumonitis
Pneumonitis describes general inflammation of lung tissue. Possible causative agents include radiation therapy of the chest, exposure to medications used during chemo-therapy, the inhalation of debris (e.g., animal dander), aspiration, herbicides or fluorocarbons and some systemic diseases. If unresolved, continued inflammation can result in irreparable damage such as pulmonary fibrosis. Pneumonitis is distinguished from pneumonia on the basis of causation as well as its manifestation. Pneumonia can be described as pneumonitis combined with consolidation and exudation of lung tissue due to infection with microorganisms. The distinction between Pneumonia and Pneumonitis can be further understood with Pneumonitis being the encapsulation of all respiratory infections (incorporating pneumonia and pulmonary fibrosis as major diseases), and pneumonia as a localized infection. For most infections, the immune response of the body is enough to control and apprehend the infection within a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azelaic Acid
Azelaic acid (AzA) is an organic compound with the formula HOOC(CH2)7 COOH. This saturated dicarboxylic acid exists as a white powder. It is found in wheat, rye, and barley. It is a precursor to diverse industrial products including polymers and plasticizers, as well as being a component of a number of hair and skin conditioners. AzA inhibits tyrosinase. Production Azelaic acid is industrially produced by the ozonolysis of oleic acid. The side product is nonanoic acid. It is produced naturally by ''Malassezia furfur'' (also known as ''Pityrosporum ovale''), a yeast that lives on normal skin. The bacterial degradation of nonanoic acid gives azelaic acid. Biological function In plants, azelaic acid serves as a "distress flare" involved in defense responses after infection. It serves as a signal that induces the accumulation of salicylic acid, an important component of a plant's defensive response. Applications Polymers and related materials Esters of this dicarboxylic acid f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melasma
Melasma (also known as chloasma faciei,James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. . or the mask of pregnancy when present in pregnant women) is a tan or dark skin discoloration. Melasma is thought to be caused by sun exposure, genetic predisposition, hormone changes, and skin irritation. Although it can affect anyone, it is particularly common in women, especially pregnant women and those who are taking oral or patch contraceptives or hormone replacement therapy medications. Signs and symptoms The symptoms of melasma are dark, irregular, well-demarcated, hyperpigmented macules to patches. These patches often develop gradually over time. Melasma does not cause any other symptoms beyond the cosmetic discoloration. Patches can vary in size from 0.5 cm to larger than 10 cm depending on the person. Its location can be categorized as centrofacial, malar, or mandibular. The most common is ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tranexamic Acid
Tranexamic acid (TXA) is a medication used to treat or prevent excessive blood loss from major trauma, postpartum bleeding, surgery, tooth removal, nosebleeds, and heavy menstruation. It is also used for hereditary angioedema. It is taken either orally or by injection into a vein. Mechanism of action Tranexamic acid is a synthetic analog of the amino acid lysine. It serves as an antifibrinolytic by reversibly binding four to five lysine receptor sites on plasminogen. This decreases the conversion of plasminogen to plasmin, preventing fibrin degradation and preserving the framework of fibrin's matrix structure. Tranexamic acid has roughly eight times the antifibrinolytic activity of an older analogue, ε-aminocaproic acid. Tranexamic acid also directly inhibits the activity of plasmin with weak potency ( IC50 = 87 mM), and it can block the active-site of urokinase plasminogen activator (uPA) with high specificity ( Ki = 2 mM), one of the highest among all the serine proteases. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antioxidant
Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricants, to prevent oxidation, and to foods to prevent spoilage, in particular the rancidification of oils and fats. In cells, antioxidants such as glutathione, mycothiol or bacillithiol, and enzyme systems like superoxide dismutase, can prevent damage from oxidative stress. The only dietary antioxidants are vitamins A, C, and E, but the term ''antioxidant'' has also been applied to numerous other dietary compounds that only have antioxidant properties in vitro, with little evidence for antioxidant properties in vivo. Dietary supplements marketed as antioxidants have not been shown to maintain health or prevent disease in humans. History As part of their adaptation from marine life, terrestrial plants began producing non-marine antioxi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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