| DSST | Digit Symbol Substitution Task |
|---|---|
| AFD | accelerated freeze drying; acrofacial dysostosis |
| FD | familial dysautonomia; family doctor; fan douche; fatal dose; fetal danger; fibrin derivative; fibro... |
| QF | quality factor; query fever; quick freeze; relative biological effectiveness |
| FS | freeze substitution |
|---|---|
| DSS | Digit Symbol Substitution |
| D.S. | degree of substitution |
| DFDBA | DEMINERALIZED freeze-dried bone allograft |
| FD | Freeze drying |
| freeze substitution | A modification of the freeze-drying method in which the ice within the frozen tissue is replaced by alcohol or other solvent at a very low temperature. (12 Dec 1998) |
|---|
| freeze | 1. To become congealed by cold; to be changed from a liquid to a solid state by the abstraction of heat; to be hardened into ice or a like solid body. Water freezes at 32 deg above zero by Fahrenheit's thermometer; mercury freezes at 40 deg below zero. 2. To become chilled with cold, or as with cold; to suffer loss of animation or life by lack of heat; as, the blood freezes in the veins. To freeze up ( Origin: OE. Fresen, freosen, AS. Freosan; akin to D. Vriezen, OHG. Iosan, G. Frieren, Icel. Frjsa, Sw. Frysa, Dan. Fryse, Goth. Frius cold, frost, and prob. To L. Prurire to itch, E. Prurient, cf. L. Prna a burning coal, pruina hoarfrost, Skr. Prushva ice, prush to spirt. 18. Cf. Frost. Source: Websters Dictionary (01 Mar 1998) |
|---|---|
| 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) |
| freeze-drying | <technique> Method commonly adopted to produce a dry and stable form of biological material that has not been seriously denatured. By freezing the specimen, often with liquid nitrogen and then subliming water from the specimen under vacuum, proteins are left in reasonably native form and can usually be rehydrated to an active state. Since the freeze dried material will store without refrigeration for long periods, it is a convenient method for holding back up or reference material or for the distribution of antibiotics, vaccines etc. Synonym: lyophilization. (18 Sep 2002) |
| freeze etch | <microscopy, technique> A method of preparing a cell for study by freezing it, cracking it open to reveal the organelles, freeze drying it, then examining it under the electron microscope. (09 Oct 1997) |
| freeze etching | If a freeze fractured specimen is left for any length of time before shadowing, then water will sublime off from the specimen etching (lowering) those surfaces that are not protected by a lipid bilayer. Some etching will take place following any freeze cleavage process, in deep etching the ice surface is substantially lowered to reveal considerable detail of, for example: cytoplasmic filament systems. (18 Nov 1997) |
| freeze fracture | 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) |
| freeze fracturing | Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica. (12 Dec 1998) |
| amino acid substitution | The naturally occurring or experimentally induced replacement of one or more amino acids in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties. (12 Dec 1998) |
| base substitution | <molecular biology> One nucleotide base is replaced by another in a DNA molecule. This is also called a point mutation. (09 Oct 1997) |
| conservative substitution | In a gene product, a substitution of one amino acid with another with generally similar properties (size, hydrophobicity, etc), such that the overall functioning is likely not to be seriously affected. (18 Nov 1997) |
| stimulus substitution | <psychology> Learning that takes place when a conditioned stimulus is paired with an unconditioned stimulus. (12 Dec 1998) |
| substitution | 1. The act of putting one thing in the place of another, especially the chemical replacement of one element or radical by some other. 2. A defense mechanism, operating unconsciously, in which an unattainable or unacceptable goal, emotion or object is replaced by one that is attainable or acceptable. Origin: L. Substitutio, from statuere = to place (18 Nov 1997) |
| substitution mutation | A mutation caused by a nucleotide base being replaced by a different one. (09 Oct 1997) |
| substitution product | A product obtained by replacing one atom or group in a molecule with another atom or group. (05 Mar 2000) |
| substitution therapy | Replacement therapy, particularly when replacement is not physiological but entails administration of a substitute. (05 Mar 2000) |
Synonyms : Substitution, Freeze
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