| disc sequestration | <radiology> Complete separation of disc material with rupture through posterior longitudinal ligament into the epidural space; free fragment herniation findings: migration superiorly/inferiorly with compression of nerve roots above/below the level of herniation, disc material noted more than 9mm from disc space Differential diagnosis: postoperative scarring (retraction of thecal sac to the site of surgery), epidural abscess/tumour, conjoined nerve root: 2 nerve roots arising simultaneously from the thecal sac; normal variant in 1-3% see: degenerative disc disease (12 Dec 1998) |
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| imaginal disc | Epithelial infoldings in the larvae of holometabolous insects (e.g. Lepidoptera, Diptera) that rapidly develop into adult appendages (legs, antennae, wings etc.) during metamorphosis from larval to adult form. By implanting discs into the haemocoele of an adult insect their differentiation can be blocked, though their determination remains unchanged except occasionally (transdetermination). The hierarchy of transdetermination has been studied in great detail in Drosophila. (11 Mar 1998) |
| intercalated disc | An electron dense junctional complex, at the end to end contacts of cardiac muscle cells, that contains gap junctions and desmosomes. most of the disc is formed of a convoluted fascia adherens type of junction into which the actin filaments of the terminal sarcomeres insert (they are therefore equivalent to half Z bands), desmosomes are also present. The lateral portion of the stepped disc contains gap junctions that couple the cells electrically and thus coordinate the contraction. (18 Nov 1997) |
| interpubic disc | The disk of fibrocartilage that unites the pubic bones at the pubic symphysis. Synonym: discus interpubicus, interpubic disk, lamina fibrocartilaginea interpubica. (05 Mar 2000) |
| tilting disc valve | A variety of prosthetic cardiac valve composed of one or two discs within a retaining device. (05 Mar 2000) |
| tilting disc valve prosthesis | A low profile artificial heart valve with excellent flow characteristics. (05 Mar 2000) |
| electrophoresis, disc | Electrophoresis in which discontinuities in both the voltage and pH gradients are introduced by using buffers of different composition and pH in the different parts of the gel column. The term 'disc' was originally used as an abbreviation for 'discontinuous' referring to the buffers employed, and does not have anything to do with the shape of the separated zones. (12 Dec 1998) |
| excavation of optic disc | The normally occurring depression or pit in the centre of the optic disc. Synonym: excavatio disci, depression of optic disk, excavatio papillae, physiologic cup, physiologic excavation. (05 Mar 2000) |
| Z disc | <cell biology> Region of the sarcomere into which thin filaments are inserted. Location of _ actinin in the sarcomere. (18 Nov 1997) |
| affective personality disorder | A disturbance of feelings or mood expressed as a milder form of depression and related emotional features that colour the whole psychic life and for which psychosocial stressors are believed to play the major role. (05 Mar 2000) |
| alcohol amnestic disorder | <psychiatry> A mental disorder with brain damage characterised by amnesia, compensatory confabulation, disturbance of attention, and peripheral neuritis. It is usually associated with alcoholism and dietary deficiencies. (12 Dec 1998) |
| antisocial personality disorder | <psychiatry> An individual who engages in deviant behaviour with lack of remorse. (13 Jan 1998) |
| asthenic personality disorder | A personality type characterised by low energy level, easy fatigability, incapacity for enjoyment, lack of enthusiasm, and oversensitivity to physical and emotional stress. When appearing in marked form it becomes a psychological disorder (asthenic personality disorder), also called dependent personality. Synonym: asthenic personality disorder, dependent personality disorder. (05 Mar 2000) |
| attention deficit disorder | An inability to control behaviour due to difficulty in processing neural stimuli. (12 Dec 1998) |
| attention deficit disorder with hyperactivity | A behaviour disorder originating in childhood in which the essential features are signs of developmentally inappropriate inattention, impulsivity, and hyperactivity. Although most individuals have symptoms of both inattention and hyperactivity-impulsivity, one or the other pattern may be predominant. The disorder is more frequent in males than females. Onset is in childhood. Symptoms often attenuate during late adolescence although a minority experience the full complement of symptoms into mid-adulthood. (12 Dec 1998) |