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Skin Sloughing
Skin sloughing is the process of shedding dead surface cells from the skin. It is most associated with cosmetic skin maintenance via exfoliation, but can also occur biologically or for medical reasons. Cellular Process Skin Composition Keratinocytes are the main cell type of the epidermis. They form several layers of the skin. Life for a keratinocyte begins at the stratum basale layer. Cells here proliferate and move through the stratum spinosum and stratum granulosum. The topmost layer is called the stratum corneum. During sloughing, it is this layer that is removed. As cells progress through the various layers to reach the stratum corneum, they undergo a process called cornification which transforms keratinocytes to corneocytes, effectively killing them. The resulting cell is flat, has no nucleus, and is surrounded by a cellular envelope. Regulation of the Epidermis Calcium is the main regulator of keratinocytes and cornification. A calcium concentration gradient differen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exfoliation (cosmetology)
Exfoliation is the removal of dead skin cells and built-up dirt from the skin's surface. The term comes from the Latin word ''exfoliare'' (to strip off leaves). This is a regular practice within the cosmetic industry, both for its outcome of promoting skin regeneration as well as providing a deep cleanse of the skin barrier. Being used in facials, this process can be achieved by mechanical or chemical means, such as microdermabrasion or chemical peels. Exfoliants are advertised as treatments that enhance beauty and promote a youthful and healthy appearance. History Exfoliation was first practiced among the ancient Egyptians. This was also used in Asia, specifically in China, during the Qing Dynasty (1644–1944). Mechanical Exfoliation Mechanical exfoliation methods involve physically scrubbing the skin with an abrasive material. These types of exfoliants include microfiber cloths, adhesive exfoliation sheets, micro-bead facial scrubs, crêpe paper, crushed apricot kernel or a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermatophyte
Dermatophyte (from Greek '' derma'' "skin" (GEN ''dermatos'') and ''phyton'' "plant") is a common label for a group of fungus of ''Arthrodermataceae'' that commonly causes skin disease in animals and humans. Traditionally, these anamorphic (asexual or imperfect fungi) mold genera are: ''Microsporum'', ''Epidermophyton'' and ''Trichophyton''. There are about 40 species in these three genera. Species capable of reproducing sexually belong in the teleomorphic genus Arthroderma, of the Ascomycota (see Teleomorph, anamorph and holomorph for more information on this type of fungal life cycle). As of 2019 a total of nine genera are identified and new phylogenetic taxonomy has been proposed. Dermatophytes cause infections of the skin, hair, and nails, obtaining nutrients from keratinized material. The organisms colonize the keratin tissues causing inflammation as the host responds to metabolic byproducts. Colonies of dermatophytes are usually restricted to the nonliving cornified laye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Proliferation
Cell proliferation is the process by which ''a cell grows and divides to produce two daughter cells''. Cell proliferation leads to an exponential increase in cell number and is therefore a rapid mechanism of tissue growth. Cell proliferation requires both cell growth and cell division to occur at the same time, such that the average size of cells remains constant in the population. Cell division can occur without cell growth, producing many progressively smaller cells (as in cleavage of the zygote), while cell growth can occur without cell division to produce a single larger cell (as in growth of neurons). Thus, cell proliferation is not synonymous with either cell growth or cell division, despite the fact that these terms are sometimes used interchangeably. Stem cells undergo cell proliferation to produce proliferating "transit amplifying" daughter cells that later differentiate to construct tissues during normal development and tissue growth, during tissue regeneration aft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (biology)
Transcription is the process of copying a segment of DNA into RNA. The segments of DNA transcribed into RNA molecules that can encode proteins are said to produce messenger RNA (mRNA). Other segments of DNA are copied into RNA molecules called non-coding RNAs (ncRNAs). mRNA comprises only 1–3% of total RNA samples. Less than 2% of the human genome can be transcribed into mRNA ( Human genome#Coding vs. noncoding DNA), while at least 80% of mammalian genomic DNA can be actively transcribed (in one or more types of cells), with the majority of this 80% considered to be ncRNA. Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. Transcription proceeds in the following general steps: # RNA polymerase, together with one or more general transcription factors, binds to promoter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Map Kinase
A mitogen-activated protein kinase (MAPK or MAP kinase) is a type of protein kinase that is specific to the amino acids serine and threonine (i.e., a serine/threonine-specific protein kinase). MAPKs are involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock and proinflammatory cytokines. They regulate cell functions including proliferation, gene expression, differentiation, mitosis, cell survival, and apoptosis. MAP kinases are found in eukaryotes only, but they are fairly diverse and encountered in all animals, fungi and plants, and even in an array of unicellular eukaryotes. MAPKs belong to the CMGC (CDK/MAPK/GSK3/CLK) kinase group. The closest relatives of MAPKs are the cyclin-dependent kinases (CDKs). Discovery The first mitogen-activated protein kinase to be discovered was ERK1 (MAPK3) in mammals. Since ERK1 and its close relative ERK2 (MAPK1) are both involved in growth factor signaling, the family ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Receptor Tyrosine Kinase
Receptor tyrosine kinases (RTKs) are the high-affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones. Of the 90 unique tyrosine kinase genes identified in the human genome, 58 encode receptor tyrosine kinase proteins. Receptor tyrosine kinases have been shown not only to be key regulators of normal cellular processes but also to have a critical role in the development and progression of many types of cancer. Mutations in receptor tyrosine kinases lead to activation of a series of signalling cascades which have numerous effects on protein expression. Receptor tyrosine kinases are part of the larger family of protein tyrosine kinases, encompassing the receptor tyrosine kinase proteins which contain a transmembrane domain, as well as the non-receptor tyrosine kinases which do not possess transmembrane domains. History The first RTKs to be discovered were EGF and NGF in the 1960s, but the classification of receptor tyrosine kinases was not d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psoriasis
Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small, localized patches to complete body coverage. Injury to the skin can trigger psoriatic skin changes at that spot, which is known as the Koebner phenomenon. The five main types of psoriasis are plaque, guttate, inverse, pustular, and erythrodermic. Plaque psoriasis, also known as psoriasis vulgaris, makes up about 90% of cases. It typically presents as red patches with white scales on top. Areas of the body most commonly affected are the back of the forearms, shins, navel area, and scalp. Guttate psoriasis has drop-shaped lesions. Pustular psoriasis presents as small, noninfectious, pus-filled blisters. Inverse psoriasis forms red patches in skin folds. Erythrodermic psoriasis occurs when the rash becomes very widespread, and can develop from any of the other types. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seborrhoeic Dermatitis
Seborrhoeic dermatitis, sometimes inaccurately referred to as seborrhoea, is a long-term skin disorder. Symptoms include red, scaly, greasy, itchy, and inflamed skin. Areas of the skin rich in oil-producing glands are often affected including the scalp, face, and chest. It can result in social or self-esteem problems. In babies, when the scalp is primarily involved, it is called cradle cap. Dandruff is a milder form of the condition without inflammation. The cause is unclear but believed to involve a number of genetic and environmental factors. Risk factors include poor immune function, Parkinson's disease, and alcoholic pancreatitis. The condition may worsen with stress or during the winter. The ''Malassezia'' yeast is believed to play a role. It is not a result of poor hygiene. Diagnosis is typically based on the symptoms. The condition is not contagious. The typical treatment is antifungal cream and anti-inflammatory agents. Specifically, ketoconazole or ciclopirox are effect ... [...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] |
Atopic Dermatitis
Atopic dermatitis (AD), also known as atopic eczema, is a long-term type of inflammation of the skin (dermatitis). It results in puritis, itchy, red, swollen, and cracked skin. Clear fluid may come from the affected areas, which often thickens over time. While the condition may occur at any age, it typically starts in childhood, with changing severity over the years. In children under one year of age, much of the body may be affected. As children get older, the areas on the insides of the knees and elbows are most commonly affected. In adults, the hands and feet are most commonly affected. Scratching the affected areas worsens the symptoms, and those affected have an increased risk of skin infections. Many people with atopic dermatitis develop hay fever or asthma. The cause is unknown but believed to involve genetics, immune system dysfunction, environmental exposures, and difficulties with the Semipermeable membrane, permeability of the skin. If one identical twin is affected, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermatitis
Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can vary from small to covering the entire body. Dermatitis is often called eczema, and the difference between those terms is not standardized. The exact cause of the condition is often unclear. Cases may involve a combination of allergy and poor venous return. The type of dermatitis is generally determined by the person's history and the location of the rash. For example, irritant dermatitis often occurs on the hands of those who frequently get them wet. Allergic contact dermatitis occurs upon exposure to an allergen, causing a hypersensitivity reaction in the skin. Prevention of atopic dermatitis is typically with essential fatty acids, and may be treated with moisturizers and steroid creams. The steroid creams should generally be of mid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scarlet Fever
Scarlet fever, also known as Scarlatina, is an infectious disease caused by ''Streptococcus pyogenes'' a Group A streptococcus (GAS). The infection is a type of Group A streptococcal infection (Group A strep). It most commonly affects children between five and 15 years of age. The signs and symptoms include a sore throat, fever, headache, swollen lymph nodes, and a characteristic rash. The face is flushed and the rash is red and blanching. It typically feels like sandpaper and the tongue may be red and bumpy. The rash occurs as a result of capillary damage by exotoxins produced by ''S.pyogenes''. On darker pigmented skin the rash may be hard to discern. Scarlet fever affects a small number of people who have strep throat or streptococcal skin infections. The bacteria are usually spread by people coughing or sneezing. It can also be spread when a person touches an object that has the bacteria on it and then touches their mouth or nose. The diagnosis is typically confirmed by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
