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Demodex Folliculorum
''Demodex folliculorum'' is a microscopic mite that can only survive on the skin of humans. Most people have ''D.folliculorum'' on their skin. Usually, the mites do not cause any harm, so are considered an example of commensalism rather than parasitism. ''D.folliculorum''-caused disease, though, is known as demodicosis. Anatomy Due to being adapted to live inside hair follicles, ''D. folliculorum'' is thin and worm-like, with short legs. As an adult, ''D.folliculorum'' measures long. Adults have four pairs of legs; larvae and nymphs have only three pairs. ''D.folliculorum'' has a rudimentary gut and anus. Reproduction and life cycle The entire life cycle of ''D.folliculorum'' takes 14–16 days. Adult mites copulate at the top of the hair follicle, near the skin surface. Eggs are deposited in the sebaceous gland inside the hair follicle. The heart-shaped egg is long, and hatches into a six-legged larva. Seven days are needed for the larva to develop into a mature adult, with t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mite
Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evidence of a close relationship. Most mites are tiny, less than in length, and have a simple, unsegmented body plan. The small size of most species makes them easily overlooked; some species live in water, many live in soil as decomposers, others live on plants, sometimes creating galls, while others again are Predation, predators or Parasitism, parasites. This last type includes the commercially destructive ''Varroa'' parasite of honey bees, as well as scabies mites of humans. Most species are harmless to humans, but a few are associated with allergies or may transmit diseases. The scientific discipline devoted to the study of mites is called acarology. Evolution and taxonomy The mites are not a defined taxon, but is used for two disti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Innate Immune Response
The innate, or nonspecific, immune system is one of the two main immunity strategies (the other being the adaptive immune system) in vertebrates. The innate immune system is an older evolutionary defense strategy, relatively speaking, and is the dominant immune system response found in plants, fungi, insects, and primitive multicellular organisms (see Beyond vertebrates).. The major functions of the innate immune system are to: * recruit immune cells to infection sites by producing chemical factors, including chemical mediators called cytokines * activate the complement cascade to identify bacteria, activate cells, and promote clearance of antibody complexes or dead cells * identify and remove foreign substances present in organs, tissues, blood and lymph, by specialized white blood cells * activate the adaptive immune system through antigen presentation * act as a physical and chemical barrier to infectious agents; via physical measures such as skin and chemical measures such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trombidiformes
The Trombidiformes are a large, diverse order of mites. Taxonomy In 1998, Trombidiformes was divided into the Sphaerolichida and the Prostigmata. The group has few synapomorphies by which it can be defined, unlike the other major group of acariform mites, Sarcoptiformes. Its members include medically important mites (such as ''Demodex'', the chiggers, and scrub-itch mites) and many agriculturally important species, including the spider mites (Tetranychidae). The superfamily Eriophyoidea, traditionally considered members of the Trombidiformes, have been found to be basal mites in genomic analyses, sister to the clade containing Sarcoptiformes and Trombidiformes. The 2004 classification retained the two suborders, comprising around 125 families and more than 22,000 described species. In the 2011 revised classification, the order now contains 151 families, 2235 genera and 25,821 species, and there were another 10 species with 24 species that present only as fossils. These 151 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Microbiome
The human microbiome is the aggregate of all microbiota that reside on or within human tissues and biofluids along with the corresponding anatomical sites in which they reside, including the skin, mammary glands, seminal fluid, uterus, ovarian follicles, lung, saliva, oral mucosa, conjunctiva, biliary tract, and gastrointestinal tract. Types of human microbiota include bacteria, archaea, fungi, protists and viruses. Though micro-animals can also live on the human body, they are typically excluded from this definition. In the context of genomics, the term ''human microbiome'' is sometimes used to refer to the collective genomes of resident microorganisms; however, the term '' human metagenome'' has the same meaning. Humans are colonized by many microorganisms, with approximately the same order of magnitude of non-human cells as human cells. Some microorganisms that colonize humans are commensal, meaning they co-exist without harming humans; others have a mutualistic relationsh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Demodex Brevis
''Demodex brevis'' is one of the two species of face mite that inhabit humans (the other being ''Demodex folliculorum''). They are very similar to ''Demodex folliculorum'', with just a few differences. They are usually found in the sebaceous glands of the human body. The same way that ''D. folliculorum'' reproduces in the follicles, ''D. brevis'' reproduces in the sebaceous glands. Under normal conditions they are not harmful, and are considered to be commensals (the mite benefits but there is no harm or benefit to the host) rather than parasites (where the host is harmed) or mutualistic organisms (where the host is benefitted). During a severe infestation, though, there may be adverse effects on the host, such as demodicosis Demodicosis , also called Demodex folliculitis in humans and demodectic mange () or red mange in animals, is caused by a sensitivity to and overpopulation of ''Demodex, Demodex spp.'' as the host's immune system is unable to keep the mites under .... ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Owen
Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils. Owen produced a vast array of scientific work, but is probably best remembered today for coining the word '' Dinosauria'' (meaning "Terrible Reptile" or "Fearfully Great Reptile"). An outspoken critic of Charles Darwin's theory of evolution by natural selection, Owen agreed with Darwin that evolution occurred, but thought it was more complex than outlined in Darwin's ''On the Origin of Species''. Owen's approach to evolution can be considered to have anticipated the issues that have gained greater attention with the recent emergence of evolutionary developmental biology. Owen was the first president of the Microscopical Society of London in 1839 and edited many issues of its journal – then known as ''The Microscopic Journal''. Owen also c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Demodex
''Demodex'' is a genus of tiny mites that live in or near hair follicles of mammals. Around 65 species of ''Demodex'' are known. Two species live on humans: ''Demodex folliculorum'' and ''Demodex brevis'', both frequently referred to as eyelash mites, alternatively face mites or skin mites. Different species of animals host different species of ''Demodex''. ''Demodex canis'' lives on the domestic dog. The presence of ''Demodex'' species on mammals is common and usually does not cause any symptoms, although occasionally some skin diseases can be caused by the mites. ''Demodex'' is derived from Greek δημός ''dēmos'' "fat" and δήξ ''dēx'', "woodworm". Notable species ''D. folliculorum'' and ''D. brevis'' ''D. folliculorum'' and ''D. brevis'' are typically found on humans. ''D. folliculorum'' was first described in 1842 by Simon; ''D. brevis'' was identified as separate in 1963 by Akbulatova. ''D. folliculorum'' is found in hair follicles, while ''D. brevis'' lives in seb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedrich Gustav Jakob Henle
Friedrich Gustav Jakob Henle (; 9 July 1809 – 13 May 1885) was a German physician, pathologist, and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay, "On Miasma and Contagia," was an early argument for the germ theory of disease. He was an important figure in the development of modern medicine. Biography Henle was born in Fürth, Bavaria, to Simon and Rachel Diesbach Henle (Hähnlein). He was Jewish. After studying medicine at Heidelberg and at Bonn, where he took his doctor's degree in 1832, he became prosector in anatomy to Johannes Müller at Berlin. During the six years he spent in that position he published a large amount of work, including three anatomical monographs on new species of animals and papers on the structure of the lymphatic system, the distribution of epithelium in the human body, the structure and development of the hair, and the formation of mucus and pus. In 1840, he accepted the chair of anatomy at Zürich an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunosuppression
Immunosuppression is a reduction of the activation or efficacy of the immune system. Some portions of the immune system itself have immunosuppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other conditions. In general, deliberately induced immunosuppression is performed to prevent the body from rejecting an organ transplant. Additionally, it is used for treating graft-versus-host disease after a bone marrow transplant, or for the treatment of auto-immune diseases such as systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, or Crohn's disease. This is typically done using medications, but may involve surgery (splenectomy), plasmapheresis, or radiation. A person who is undergoing immunosuppression, or whose immune system is weak for some other reasons (such as chemotherapy or HIV), is said to be ''immunocompromised''. Deliberately induced Administration of immunosuppressive medic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delayed Hypersensitivity
Type IV hypersensitivity, often called delayed-type hypersensitivity, is a type of hypersensitivity reaction that can take a day or more to develop. Unlike the other types, it is not humoral (not antibody-mediated) but rather is a type of cell-mediated response. This response involves the interaction of T cells, monocytes, and macrophages. This reaction is caused when CD4+ Th1 cells recognize foreign antigen in a complex with the MHC class II on the surface of antigen-presenting cells. These can be macrophages that secrete IL-12, which stimulates the proliferation of further CD4+ Th1 cells. CD4+ T cells secrete IL-2 and interferon gamma (IFNγ), inducing the further release of other Th1 cytokines, thus mediating the immune response. Activated CD8+ T cells destroy target cells on contact, whereas activated macrophages produce hydrolytic enzymes and, on presentation with certain intracellular pathogens, transform into multinucleated giant cells. The over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commensalism
Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit from each other; amensalism, where one is harmed while the other is unaffected; parasitism, where one is harmed and the other benefits, and parasitoidism, which is similar to parasitism but the parasitoid has a free-living state and instead of just harming its host, it eventually ends up killing it. The commensal (the species that benefits from the association) may obtain nutrients, shelter, support, or locomotion from the host species, which is substantially unaffected. The commensal relation is often between a larger host and a smaller commensal; the host organism is unmodified, whereas the commensal species may show great structural adaptation consistent with its habits, as in the remoras that ride attached to sharks and other fishes. Remo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acne Rosacea
Acne, also known as ''acne vulgaris'', is a long-term skin condition that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and possible scarring. It primarily affects skin with a relatively high number of oil glands, including the face, upper part of the chest, and back. The resulting appearance can lead to anxiety, reduced self-esteem, and, in extreme cases, depression or thoughts of suicide. Susceptibility to acne is primarily genetic in 80% of cases. The roles of diet and cigarette smoking in the condition are unclear, and neither cleanliness nor exposure to sunlight appear to play a part. In both sexes, hormones called androgens appear to be part of the underlying mechanism, by causing increased production of sebum. Another common factor is the excessive growth of the bacterium ''Cutibacterium acnes'', which is present on the skin. Treatments for acne are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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