| transdermal | <pharmacology> Entering through the dermis or skin, as in administration of a drug applied to the skin in ointment or patch form. (17 Mar 1998) |
|---|---|
| transdermic | <technique> Performed through the skin, as injection of radiopacque material in radiological examination or the removal of tissue for biopsy accomplished by a needle. Origin: L. Cutis = skin (18 Nov 1997) |
| transdetermination | <cell biology> Change in determined state observed in experiments on Drosophila imaginal discs. These can be cultured for many generations in the abdomen of an adult, where they proliferate but do not differentiate. If transplanted into a larva, they differentiate after pupation according to the disc from which they were derived, they maintain their determination. Occasionally the disc will differentiate into a structure appropriate to another disc. This is termed transdetermination. It is a rare event, involves a population of cells and certain changes are more common than others, e.g. Leg to wing is more frequent than wing to leg. (17 Mar 1998) |
| transdifferentiation | <cell biology> Change of a cell or tissue from one differentiated state to another. Rare and has mainly been observed with cultured cells. <zoology> In newts the pigmented cells of the iris transdifferentiate to form lens cells if the existing lens is removed. (17 Mar 1998) |
| transduce | To effect transduction. (05 Mar 2000) |
| transducer | <physics> A device that transforms one type of energy to another. (17 Mar 1998) |
| transducer cell | Any cell responding to a mechanical, thermal, photic, or chemical stimulus by generating an electrical impulse synaptically transmitted to a sensory neuron in contact with the cell. (05 Mar 2000) |
| transducers | Any device or element which converts an input signal into an output signal of a different form. Examples include the microphone, phonographic pickup, loudspeaker, barometer, photelectric cell, automobile horn, doorbell, and underwater sound transducer. (12 Dec 1998) |
| transducers, pressure | Transducers that are activated by pressure changes, e.g., blood pressure. (12 Dec 1998) |
| transducin | <protein> A GTP-binding protein found in the disc membrane of retinal rods and cones: of the part of the cascade involved in transduction of light to a nervous impulse. A complex of three subunits, alpha (39 kD), beta (36 kD) and gamma (8 kD). Photoexcited rhodopsin interacts with transducin and promotes the exchange of GTP for GDP on the _ subunit. The GTP _ subunit dissociates from the complex and activates a cGMP phospodiesterase by removing an inhibitory subunit. The _ subunit of transducin can be ADP ribosylated by cholera toxin and pertussis toxin. (18 Nov 1997) |
| transducin GTP phosphohydrolase | <enzyme> Stimulated by bovine rhodopsin mutants (asp63 to asn) and (glu134 to gln) with slightly lowered efficiency Registry number: EC 3.6.1.- Synonym: transducin GTPase (26 Jun 1999) |
| transductant | A cell that has acquired a new character by means of transduction; may be complete, with integration of the transferred genetic fragment into its genome, or abortive, in which case the genetic fragment is not integrated and passes to only one of the two daughter cells on division. (05 Mar 2000) |
| transduction | 1. <molecular biology> The transfer of a gene from one bacterium to another by a bacteriophage. In generalised transduction any gene may be transferred as a result of accidental incorporation during phage packaging. In specialised transduction only specific genes can be transferred, as a result of improper recombination out of the host chromosome of the prophage of a lysogenic phage. Transduction is an infrequent event but transducing phages have proved useful in the genetic analysis of bacteria. 2. <biology, physics> The conversion of a signal from one form to another. For example: various types of sensory cells convert or transduce light, pressure, chemicals, etc. Into nerve impulses and the binding of many hormones to receptors at the cell surface is transduced into an increase in cAMP within the cell. (17 Mar 1998) |
| transduction, genetic | Transfer of bacterial DNA by phages from the infected bacterium in which the DNA originates to another bacterium. (12 Dec 1998) |
| transduodenal sphincterotomy | Division of Oddi's sphincter; an operation to open the lower end of the common duct to remove impacted stones or to relieve spasm or stricture of the terminal bile and pancreatic ducts. (05 Mar 2000) |