| cross flap | A skin flap transferred from one part of the body to a corresponding part, as from one arm to the other. (05 Mar 2000) |
|---|---|
| cross-hybridisation | <molecular biology> The hydrogen bonding of asingle-stranded DNA sequence that is partially but not entirely complementary to a single-stranded substrate. Often, this involves hybridising a DNA probe for a specific DNA sequence to the homologous sequences of different species. (09 Oct 1997) |
| cross hybridization | Annealing of a DNA probe to an imperfectly matching DNA molecule. (05 Mar 2000) |
| cross infection | <microbiology> Infection transmitted between individuals infected with different pathogenic microorganisms. Any infection which a patient contracts in a health-care institution. (12 Dec 1998) |
| cross-link | A covalent linkage between two polymers or between two different regions of the same polymer. (05 Mar 2000) |
| cross linking | 1. <chemistry> The linking of the chains of a polymer to one another so that the polymer, as a network, becomes stronger and more resistant to being dissolved. 2. <molecular biology> The abnormal linking of two strands of DNA by covalent bonds (as opposed to the normal hydrogen bonds between base pairs), which can occur by exposure to X-rays. Such linking is a type of damage to the DNA molecule and must be repaired before the DNA can replicate and function properly again. (09 Oct 1997) |
| cross-linking reagent | <chemistry> Reagents with two reactive groups, usually at opposite ends of the molecule, that are capable of reacting with and thereby forming bridges between side chains of amino acids in proteins; the locations of naturally reactive areas within proteins can thereby be identified; may also be used for other macromolecules, like glycoproteins, nucleic acids, or other. (12 Dec 1998) |
| cross-matching | 1. A test for incompatibility between donor and recipient blood, carried out prior to transfusion to avoid potentially lethal haemolytic reactions between the donor's red blood cells and antibodies in the recipient's plasma, or the reverse; performed by mixing a sample of red blood cells of the donor with plasma of the recipient (major crossmatch) and the red blood cells of the recipient with the plasma of the donor (minor crossmatch). Incompatibility is indicated by clumping of red blood cells and contraindicates use of the donor's blood. 2. In allotransplantation of solid organs (e.g., kidney), a test for identification of antibody in the serum of potential allograft recipients which reacts directly with the lymphocytes or other cells of a potential allograft donor; presence of these antibodies usually, if not always, contraindicates the performance of the transplantation because virtually all such grafts will be subject to a hyperacute type of rejection. (05 Mar 2000) |
| cross-pollination | <botany> Fertilization of a plant from a plant with a different genetic makeup. (09 Oct 1997) |
| cross-reacting agglutinin | An immune agglutinin specific for a group antigen. Synonym: cross-reacting agglutinin. (05 Mar 2000) |
| cross-reacting antibody | <immunology> Antibody specific for group antigens, i.e., those with identical functional groups, antibody for antigens that have functional groups of closely similar, but not identical, chemical structure. (05 Mar 2000) |
| cross-reacting material | <haematology> A substance sufficiently different from a reference substance (R) to have a perceptibly different function from R but sufficiently similar to R that it reacts with anti-R antibodies; e.g., mutant factor VIII may be defective or even inert in coagulation and yet be immunologically identified as factor VIII. (05 Mar 2000) |
| cross reaction | <haematology, immunology> Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen. (12 Dec 1998) |
| cross-reactive antibody | <haematology, immunology> Antibodies which don't respond to any one specific antigen, but will respond to a number of them. These antibodies can be responsible for false positive results in antigen-antibody tests. (09 Oct 1997) |
| cross-resistance | <immunology, microbiology> Immunologic resistance to the pathogenic effects of a microorganism because of previous exposure to another species or type having cross reactive antigens. This phenomenon is seen in microbes that acquire resistance to one drug through direct exposure and turn out to have resistance to one or more other drugs to which it has not been exposed. Cross-resistance arises because the mechanism of resistance to several drugs is the same and arises through the identical genetic mutations. (09 Oct 1997) |