| lambda bacteriophage | <virology> Bacterial DNA virus, first isolated from E. Coli. Its structure is similar to that of the T even phages. Lambda genetic material consists of a double-stranded DNA molecule with 5' twelve-base-pair sticky ends, known as cos sites, which permit circularisation of the DNA molecule. It shows a lytic cycle and a lysogenic cycle and studies on the control of these alternative cycles have been very important for our understanding of the regulation of gene transcription. It is used as a cloning vector, accommodating fragments of DNA up to 15 kilobase pairs long. For larger pieces, the cosmid vector was constructed from its ends. (14 Mar 2000) |
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| lambda chain | <immunology> Although light chains are found in many multimeric proteins, L chain usually refers to the light chains of immunoglobulins. These are of 22 kD and of one of two types, kappa or lambda. A single immunoglobulin has identical light chains (2 kappa or 2 lamda). Light chains have one variable and one constant region. There are isotype variants of both kappa and lamda. (25 Jun 1999) |
| lambda phage | <virology> Bacterial DNA virus, first isolated from E. Coli. Its structure is similar to that of the T even phages. Lambda genetic material consists of a double-stranded DNA molecule with 5' twelve-base-pair sticky ends, known as cos sites, which permit circularisation of the DNA molecule. It shows a lytic cycle and a lysogenic cycle and studies on the control of these alternative cycles have been very important for our understanding of the regulation of gene transcription. It is used as a cloning vector, accommodating fragments of DNA up to 15 kilobase pairs long. For larger pieces, the cosmid vector was constructed from its ends. (14 Mar 2000) |
| lambda sign | <radiology> Small ascending aorta: same size as right and left coronary aa., hypoplastic left heart syndrome (12 Dec 1998) |
| lambdacism | 1. Mispronunciation or disarticulation of the letter l. 2. Substitution of the letter l for the letter r. Origin: G. Lambda, the letter L (05 Mar 2000) |
| lambdoid | Resembling the Greek letter lambda, as does the lambdoid suture. Origin: Lambda + G. Eidos, resemblance (05 Mar 2000) |
| lambdoid border of occipital bone | <anatomy> The margin of the occipital squama that articulates with the parietal bones in the lambdoid suture. Synonym: margo lambdoideus squamae occipitalis, lambdoid margin of occipital bone. (05 Mar 2000) |
| lambdoid margin of occipital bone | <anatomy> The margin of the occipital squama that articulates with the parietal bones in the lambdoid suture. Synonym: margo lambdoideus squamae occipitalis, lambdoid margin of occipital bone. (05 Mar 2000) |
| lambdoid suture | <anatomy> Line of union between the occipital and the parietal bones. Synonym: sutura lambdoidea. (05 Mar 2000) |
| lambdoid suture defect | <radiology> Well-defined lucent lesion, classically unilateral, associated with neurofibromatosis (12 Dec 1998) |
| lambert | <unit> A unit of brightness; the brightness of a perfectly diffusing surface emitting or reflecting a total luminous flux of 1 lumen per sq cm of surface. Origin: J.H. Lambert, German physicist and mathematician, 1728-1777 (05 Mar 2000) |
| lambert pine | <botany> The gigantic sugar pine of California and Oregon (Pinus Lambertiana). It has the leaves in fives, and cones a foot long. The timber is soft, and like that of the white pine of the Eastern States. Origin: So called from Lambert, an English botanist. Source: Websters Dictionary (01 Mar 1998) |
| Lambert's law | Each layer of equal thickness absorbs an equal fraction of the light that traverses it; Cf.: Beer-Lambert law. The illumination of a surface on which the light falls normally from a point source is inversely proportional to the square of the distance from the source. (05 Mar 2000) |
| Lambert's syndrome | <syndrome> A condition characterised by muscle weakness that is similar to the symptoms of myasthenia gravis. For this reason, it has been referred to as myasthenic syndrome. This disorder is caused by an insufficient release of neurotransmitter (acetylcholine) by the nerve cells. Unlike myasthenia gravis, as muscle contractions are continued, strength will increase. The cause of Lambert-Eaton syndrome is unknown, but is usually associated with small cell carcinoma of the lung or an autoimmune illness. (27 Sep 1997) |
| Lambert, Edward | <person> U.S. Physician, *1915. See: Lambert-Eaton syndrome, Eaton-Lambert syndrome. (05 Mar 2000) |