| long-terminal repeat | <molecular biology> Identical DNA sequences, several hundred nucleotides long, found at either end of transposons and the proviral DNA, formed by reverse transcription of retroviral RNA. They are thought to have an essential role in integrating the transposon or provirus into the host DNA. Long terminal repeats have inverted repeats, that is, sequences close to either end are identical when read in opposite directions. In proviruses the upstream long-terminal repeat acts as a promoter and enhancer and the downstream long-terminal repeat as a polyadenylation site. Acronym: LTR (15 Nov 1997) |
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| long terminal repeat sequences | Regions of the RNA genome associated with regulation, integration, and expression of retroviruses. (05 Mar 2000) |
| long-term memory | That phase of the memory process considered the permanent storehouse of information which has been registered, encoded, passed into the short-term memory, coded, rehearsed, and finally transferred and stored for future retrieval; material and information retained in LTM underlies cognitive abilities. (05 Mar 2000) |
| long-term nonprogressor | An individual who has been infected with HIV for at least seven to twelve years (different authors use different timespans) and yet retains a CD4 cell count within the normal range. (09 Oct 1997) |
| long-term potentiation | <physiology> Increase in the strength of transmission at a synapse with repetitive use that lasts for more than a few minutes. As a form of long term synaptic plasticity it is important as a possible cellular mechanism for the basis of learning and memory storage. It has been studied most extensively at excitatory synapses onto principal neurons of the hippocampus where it was first demonstrated. Selective inhibition of NMDA receptor channels has been shown to block long-term potentiation and to block spatial learning. (12 Dec 1998) |
| long-term productivity | The capacity of a site to support forest ecosystems over generations of humans and trees as measured against some defined reference. (05 Dec 1998) |
| long-term survival | <oncology> Term used to describe the survival of leukaemia patients who have been disease free for prolonged periods of time, usually at least five years. The chance of disease returning (relapse) decreases with time. (13 Nov 1997) |
| long thoracic artery | <anatomy, artery> Origin, axillary; distribution, muscles of chest and mammary gland. Synonym: arteria thoracica lateralis, external mammary artery, long thoracic artery. (05 Mar 2000) |
| long thoracic nerve | <anatomy, nerve> Arises from the fifth, sixth, and seventh cervical nerves (roots of brachial plexus), descends the neck behind the brachial plexus, and is distributed to the serratus anterior muscle; it is somewhat unusual in that it courses on the superficial aspect of the muscle is supplies; its paralysis results in "winged scapula". Synonym: nervus thoracicus longus, Bell's respiratory nerve, external respiratory nerve of Bell, posterior thoracic nerve. (05 Mar 2000) |
| long thoracic vein | <anatomy, vein> Incorrect term for lateral thoracic vein. (05 Mar 2000) |
| long ton | (shipping ton) 2,240 pounds. Commonly used in Great Britain. (05 Dec 1998) |
| long-tongue | torticollis Previous: writing, writing hand, wrongful life, wrought wire, wrybill, wrymouthNext: wry neck, wuchereria, wuchereria bancrofti, Wuchereria malayilong-tongue -->wry neck 1. A twisted or distorted neck; a deformity in which the neck is drawn to one side by a rigid contraction of one of the muscles of the neck; torticollis. Medically called spasmodic torticollis, or torticollis. The most common of the focal dystonias. In torticollis, the muscles in the neck that control the position of the head are affected, causing the head to twist and turn to one side. In addition, the head may be pulled forward or backward. 2. <ornithology> Any one of several species of Old World birds of the genus Jynx, allied to the woodpeckers; especially, the common European species (J. Torguilla); so called from its habit of turning the neck around in different directions. Synonym: cuckoo's mate, snakebird, summer bird, tonguebird, and writheneck. Source: Websters Dictionary (01 Mar 1998) |
| long vinculum | A long, threadlike band that extends from the dorsal surface of each of the flexor tendons of a digit to the proximal phalanx. Synonym: vinculum longum. (05 Mar 2000) |
| long-winded | Long-breathed; hence, tediously long in speaking; consuming much time; as, a long-winded talker. Long-windedness, "A tedious, long-winded harangue." (South) Source: Websters Dictionary (01 Mar 1998) |
| abdominal pulse | The soft, compressible aortic pulse occurring in certain abdominal disorders. Synonym: pulsus abdominalis. (05 Mar 2000) |