| acquired ichthyosis | A thickening and scaling of the skin associated with some malignant diseases (e.g., Hodgkin's disease, lymphosarcoma), leprosy, and severe nutritional deficiencies. (05 Mar 2000) |
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| acquired immunity | <immunology> A form of cellular defense which identifies certain foreign substances (antigens) as harmful to the body. For this reason, the body can acquire resistance to a particular foreign agent. These foreign agents are then attacked by sensitised T lymphocytes (cellular immunity). White blood cells, plasma cells, B lymphocytes and other specialised immune system cells act in concert with T lymphocytes to produce antibodies (humoral immunity) that attach to the antigen directing T-cells to attack. Antibodies also stimulate the release of special chemical mediators in the blood (for example complement, interferon) that further enhance antigen destruction. (13 Nov 1997) |
| acquired immunodeficiency disease | Acquired immunodeficiency disease: Disease caused by infection with the human immunodeficiency virus (HIV). (12 Dec 1998) |
| Acquired Immunodeficiency Syndrome | <immunology, syndrome> An epidemic disease caused by an infection by human immunodeficiency virus (HIV-1, HIV-2), a retrovirus that causes immune system failure and debilitation and is often accompanied by infections such as tuberculosis. AIDS is spread through direct contact with bodily fluids. Acronym: AIDS (10 May 1997) |
| acquired leukoderma | <dermatology> This disorder is characterised by regions of otherwise normal skin of nonpigmented white patches of varied sizes, often symmetrically distributed and usually bordered by hyperpigmented areas. Hair in the affected areas is usually, but not always, white. (27 Sep 1997) |
| acquired leukopathia | <dermatology> This disorder is characterised by regions of otherwise normal skin of nonpigmented white patches of varied sizes, often symmetrically distributed and usually bordered by hyperpigmented areas. Hair in the affected areas is usually, but not always, white. (27 Sep 1997) |
| acquired megacolon | Megacolon occurring on the basis of an acquired disease; occurs in inflammatory bowel disease (toxic megacolon) and Chagas' disease (South American trypanosomiasis). (05 Mar 2000) |
| acquired methemoglobinaemia | Methemoglobinaemia caused by various chemical agents, such as nitrites. Synonym: enterogenous methemoglobinaemia, secondary methemoglobinaemia. (05 Mar 2000) |
| acquired mutation | A change in a gene or chromosome that occurs in a single cell after the conception of the individual. That change is then passed along to all cells descended from that cell. Acquired mutations are involved in the development of cancer. (12 Dec 1998) |
| acquired nevus | A melanocytic nevus that is not visible at birth, but appears in childhood or adult life. (05 Mar 2000) |
| acquired pellicle | A thin film (about 1 um), derived mainly from salivary glycoproteins, which forms over the surface of a cleansed tooth crown when it is exposed to the saliva. Synonym: acquired cuticle, acquired enamel cuticle, brown pellicle, posteruption cuticle. (05 Mar 2000) |
| acquired platelet function defect | <haematology> Platelet function can be affected by a number of different disease processes including polycythaemia vera, leukaemia, myelofibrosis, renal failure, multiple myeloma and some medications (for example penicillins, salicylates, phenothiazines). Disturbed blood clotting can be manifested by: easy bruising, bleeding gums, nosebleeds, abnormal vaginal bleeding, rectal bleeding, skin rash, vomiting blood, coughing up blood or blood in the urine. A measure of bleeding time and coagulation profile will be part of the evaluation. (29 Dec 1997) |
| acquired reflex | A reflex that is gradually developed by training and association through the frequent repetition of a definite stimulus. See: conditioning. Synonym: acquired reflex, behaviour reflex, trained reflex. (05 Mar 2000) |
| acquired sensitivity | 1. <immunology> A state of hypersensitivity induced by exposure to a particular antigen (allergen) resulting in harmful immunologic reactions on subsequent exposures, the term is usually used to refer to hypersensitivity to an environmental antigen (atopic allergy or contact dermatitis) or to drug allergy. The original meaning, now obsolete, included all states of altered immunologic reactivity, immunity as well as hypersensitivity. Gell and Coombs used the term allergic reaction to mean any harmful immunologic reaction causing tissue injury. 2. <study> The medical specialty dealing with diagnosis and treatment of allergic disorders. (18 Nov 1997) |
| acquired toxoplasmosis | In adults, a form of toxoplasmosis that may result in fever, encephalomyelitis, chorioretinopathy, maculopapular rash, arthralgia, myalgia, myocarditis, and pneumonitis; a lymphadenopathic form seems to be more prevalent in adults, and such persons may manifest fever, lymphadenopathy, malaise, and headache, a form frequently found in patients with AIDS. (05 Mar 2000) |