| DRID | double radial immunodiffusion; double radioisotope derivative |
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| PERK | prospective evaluation of radial keratotomy [protocol] |
| PHAVER | pterygia-heart defects-autosomal recessive inheritance-vertebral defects-ear anomalies-radial defect... |
| Ra | radial; radium; radius |
| RAD | radial artery catheter; radiation absorbed dose; radical; radiography or radiographic; reactive airw... |
| thioclastic cleavage | The splitting of a bond in fashion analogous to hydrolysis or phosphorolysis except that the elements of a substituted hydrogen sulfide (usually coenzyme A) are added across the break. (05 Mar 2000) |
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| total cleavage | Cleavage in which the blastomeres are completely separated; the entire egg participates in cell division. Synonym: complete cleavage, total cleavage. (05 Mar 2000) |
| enamel cleavage | The splitting of enamel in a plane parallel to the direction of the enamel rods. (05 Mar 2000) |
| equal cleavage | Cleavage producing blastomeres of like size. (05 Mar 2000) |
| equatorial cleavage | Cleavage in which the plane of cytoplasmic division is at right angles to the axis of the ovum. (05 Mar 2000) |
| yolk cleavage | Segmentation of the vitellus. (05 Mar 2000) |
| unequal cleavage | Cleavage producing blastomeres of different sizes at the two poles. (05 Mar 2000) |
| freeze cleavage | Method of specimen preparation for the electron microscope in which rapidly frozen tissue is cracked so as to produce a fracture plane through the specimen. The surface of the fracture plane is then shadowed by heavy metal vapour, strengthened by a carbon film and the underlying specimen is digested away, leaving a replica that can be picked up on a grid and examined in the transmission electron microscope. The great advantage of the method is that the fracture plane tends to pass along the centre of lipid bilayers and it is therefore possible to get en face views of membranes that reveal the pattern of Integral membrane proteins. The E face is the outer lamella of the plasma membrane viewed as if from within the cell, the P face the inner lamella viewed from outside the cell. Fracture planes also often pass along lines of weakness such as the interface between cytoplasm and membrane, so that outer and inner membrane surfaces can be viewed. Further information about the structure can be revealed by freeze etching. Extremely rapid freezing followed by deep etching has allowed the structure of the cytoplasm to be studied without the artefacts that might be introduced by fixation. (18 Nov 1997) |
| radial | <botany> Of or pertaining to a radius or ray; consisting of, or like, radii or rays; radiated; as, the radial artery. Radial symmetry. <biology> See Symmetry. Origin: Cf. F. Radial. See Radius. Source: Websters Dictionary (01 Mar 1998) |
| radial acceleration | The centripetal acceleration of a particle or vehicle moving along a curved path at a constant velocity; e.g., turning a curve in an automobile, pulling out of a dive, or performing a loop manoeuvre in an aircraft. In aviation, acceleration varies directly with the square of the air speed and inversely with the radius of the turn (a = V2/r, where V is air speed and r is radius of turn). (05 Mar 2000) |
| radial aplasia-thrombocytopenia syndrome | <syndrome> Aplasia (absence) of the radius (the long bone on the thumb-side of the forearm) and thrombocytopenia (low blood platelets) are key features characterizing this syndrome. There is phocomelia (flipper-limb) with the thumbs always present. The fibula (the smaller bone in the lower leg) is often absent. The risk of bleeding from too few platelets is high in early infancy but lessens with age. The condition is inherited in an autosomal recessive trait with one gene (on a non-sex chromosome) coming from each parent to the child affected with the disease. Alternative names include thrombocytopenia-absent radius syndrome, tar syndrome, and tetraphocomelia-thrombocytopenia syndrome. (12 Dec 1998) |
| radial artery | <anatomy, artery> The direct continuation of the brachial trunk, originating at the bifurcation of the brachial artery opposite the neck of the radius. Its branches may be divided into three groups corresponding to the three regions in which the vessel is situated, the forearm, wrist, and hand. (12 Dec 1998) |
| radial border of forearm | An imaginary line running along the outermost extent of the forearm separating anterior and posterior surfaces laterally. Synonym: margo lateralis antebrachii, margo radialis antebrachii, radial border of forearm. (05 Mar 2000) |
| radial bursa | <anatomy> The synovial sheath that envelops the tendon of the flexor pollicis longus in its course through the carpal canal; it is continuous with the digital sheath of the thumb, the two generally being considered as one sheath. Synonym: vagina tendinis musculi flexoris pollicis longi, radial bursa. (05 Mar 2000) |
| radial clubhand | Clubhand with angular deviation towards radial side of limb. See: manus valga. (05 Mar 2000) |