| r group | <chemistry> A chemical abbreviation that normally denotes an alkyl group, but is occasionally used to refer to other organic groups. (09 Oct 1997) |
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| Rhesus blood group | <haematology> Human blood group system with allelic red cell antigens C, D and E. The D antigen is the strongest. Red cells from a Rhesus positive foetus cross the placenta and can sensitise a Rehesus negative mother, expecially at parturition. The mother's antibody may then, in a subsequent pregnancy, cause haemolytic disease of the newborn if the foetus is Rhesus positive. The disease can be prevented by giving antiD IgG during the first 72 hours after parturition to mop up D red cells in the maternal circulation. 1st ed (18 Nov 1997) |
| rh-hr blood-group system | Erythrocyte isoantigens of the rh (rhesus) blood group system, the most complex of all human blood groups, because the genes differ by determining a different number of the over thirty antigens thus far described and do so with remarkably different quality. The major antigen rh or d is the most common cause of erythroblastosis foetalis. (12 Dec 1998) |
| chlorine group | The halogens. (05 Mar 2000) |
| group | 1. A cluster, crowd, or throng; an assemblage, either of persons or things, collected without any regular form or arrangement; as, a group of men or of trees; a group of isles. 2. An assemblage of objects in a certain order or relation, or having some resemblance or common characteristic; as, groups of strata. 3. <biology> A variously limited assemblage of animals or planta, having some resemblance, or common characteristics in form or structure. The term has different uses, and may be made to include certain species of a genus, or a whole genus, or certain genera, or even several orders. 4. A number of eighth, sixteenth, etc, notes joined at the stems; sometimes rather indefinitely applied to any ornament made up of a few short notes. Origin: F groupe, It. Gruppo, groppo, cluster, bunch, packet, group; of G. Origin: cf. G. Krepf craw, crop, tumour, bunch. See Crop. Source: Websters Dictionary (01 Mar 1998) |
| group agglutination | Agglutination by antibodies specific for minor (group) antigens common to several microorganisms, each of which possesses its own major specific antigen. Synonym: cross agglutination. (05 Mar 2000) |
| group agglutinin | An immune agglutinin specific for a group antigen. Synonym: cross-reacting agglutinin. (05 Mar 2000) |
| group antigens | Antigen's that are shared by related genera of microorganisms. (05 Mar 2000) |
| group A streptococcal necrotizing fasciitis | A complication of infection with GAS (group A streptococci) in which the bacteria attacks and destroys muscle tissue. According to the CDC, 5-10% of people with severe GAS infection develop necrotizing fasciitis. Though the infection can be treated with antibiotics, the fatality rate is close to 30%. This complication often develops as a wound infection after surgery or injury. (05 Mar 2000) |
| group A streptococci | A common bacteria that is the cause of strep throat, scarlet fever, impetigo, cellulitis-erysipelas, rheumatic fever, acute glomerular nephritis, endocarditis, and group A streptococcal necrotizing fasciitis. The prototype is Streptococcus pyogenes. (05 Mar 2000) |
| group B streptococci | A leading cause of a form of neonatal sepsis that has a 10-20% mortality rate and leaves a large number of survivors with brain damage. Also a leading cause of meningitis. (05 Mar 2000) |
| group dynamics | A term used to represent the study of underlying features of group behaviour, e.g., motives, attitudes; it is concerned with group change rather than with static characteristics. (05 Mar 2000) |
| group homes | Housing for groups of patients, children, or others who need or desire emotional or physical support. They are usually established as planned, single housekeeping units in residential dwellings that provide care and supervision for small groups of residents, who, although unrelated, live together as a family. (12 Dec 1998) |
| group hospital | A private hospital organised and controlled by a group of physicians and restricted to the reception and care of their own patients. (05 Mar 2000) |
| group III mycobacteria | Mycobacteria that are either colourless or that slowly produce a light yellow pigment when grown in the presence of light. Organisms placed in this group belong to the species Mycobacterium intracellulare. Synonym: nonchromogens. (05 Mar 2000) |