| AMC | academic medical center; acetylmethyl carbinol; Animal Medical Center; antibody-mediated cytotoxicit... |
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| AREPA | acetazolamide-responsive familial paroxysmal ataxia |
| ARSACS | autosomal recessive spastic ataxia of Charlevoix-Saguenay |
| AT | abdominal thrusts; achievement test; Achilles tendon; Achard-Thiers [syndrome]; adaptive thermogenes... |
| A-T | ataxia telangiectasia |
| dynamic psychology | A psychologic approach that concerns itself with the causes of behaviour. (05 Mar 2000) |
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| dynamic psychotherapy | Psychotherapy utilizing freudian principles. See: psychoanalysis. Synonym: dynamic psychotherapy. (05 Mar 2000) |
| dynamic range | <microscopy> In video and other electronic equipment and in photographic emulsions, the ratio of the maximum to minimum signal levels that introduce no more than acceptable levels of signal amplitude distortions. (05 Aug 1998) |
| dynamic refraction | Refraction of the eye during accommodation. (05 Mar 2000) |
| dynamic relations | Relative movements between two objects, e.g., the relationship of the mandible to the maxillae. (05 Mar 2000) |
| dynamic school | A group of theorists founded by Stahl, who professed the belief that all vital action is the result of an internal force independent of anything external to the body. (05 Mar 2000) |
| dynamic splint | A splint utilizing springs or elastic bands that aids in movements initiated by the patient by controlling the plane and range of motion. Synonym: active splint, functional splint. (05 Mar 2000) |
| dynamic viscosity | The internal or molecular frictional resistance of a fluid by Newton's law of viscosity as the ratio of the applied force per unit area to the relative velocity of adjacent fluid layers (produced by the force). (05 Mar 2000) |
| instrascene dynamic range | <microscopy> The greatest ratio of highlight to shadow brightness to within a single scene that a video camera (tube) can handle usefully. Contrast with the usable light range of a camera, which is considerably greater than the instrascene dynamic range. See: illumination, Kohler. (05 Aug 1998) |
| acute ataxia | Generalised ataxia of abrupt onset, most often caused by drug intoxications, poisonings, or vestibular neuronitis. (05 Mar 2000) |
| ataxia | <neurology> Failure of muscular coordination, irregularity of muscular action. Origin: Gr. Taxis = order (16 Dec 1997) |
| ataxia cordis | <cardiology> A condition where there is disorganised electrical conduction in the atria, resulting in ineffective pumping of blood into the ventricle. Acronym: AF (02 Jan 1998) |
| ataxia of calves | A specific cerebellar ataxia in the Jersey breed, probably a recessive genetic trait. (05 Mar 2000) |
| ataxia of lambs | Myelination failure seen in ewes on a copper-deficient diet. (05 Mar 2000) |
| ataxia-telangiectasia | <neurology, oncology> An intriguing autosomal recessive disorder in which a single defective gene produces myriad and protean effects, presents with cerebellar ataxia, telangiectasias in the eyes and skin, immune deficiency and autoimmune phenomena, propensity for lymphoid and other malignancies, excessive sensitivity to ionising radiation, increased serum alpha-fetoprotein concentrations and a tendency for chromosome breakage and translocation. A syndrome characterised by choreoathetosis beginning in childhood, progressive cerebellar ataxia, telangiectasis of conjunctiva and skin, slowly progressive mental deterioration and increasing cerebellar degeneration. There is evidence that heterozygotes show an increased susceptibility to malignancy as well, with breast cancer often cited. The gene was localised by linkage studies to chromosome 11q22-23, and recently cloned, revealing it to be homologous to the PI-3 kinase family so that prenatal diagnosis by RFLP analysis is possible. Other related genes are suspected to exist. Diagnosis in affected patients is made on clinical grounds, by detection of high concentrations of alpha-fetoprotein, and by a specialised cell culture assay for radiosensitivity and atypical radioresistant DNA synthesis. These cell culture methods are also used for prenatal diagnosis. A characteristic autopsy feature of ataxia-telangiectasia is the presence of empty basket cells in the cerebellum which results from degeneration of the previously contained Purkinje cells. Inheritance: autosomal recessive. (16 Dec 1998) |