| APR | abdominoperineal resection; absolute proximal reabsorption; acute phase reaction or reactant; amebic... |
|---|---|
| CFR | case-fatality ratio; citrovorum-factor rescue; Code of Federal Regulations; complement-fixation reac... |
| CRT | cadaveric renal transplant; cardiac resuscitation team; cathode-ray tube; certified; Certified Recor... |
| FR | failure rate; film-screen radiograph; fasciculus retroflexus; febrile reaction; feedback regulation;... |
| FW | Felix-Weil [reaction]; Folin-Wu [reaction]; fragment wound |
| primitive pit | The depression in the primitive node that serves to connect the notochordal canal with the surface ectoderm and the yolk sac. These connections are referred to as the neurenteric canal. (05 Mar 2000) |
|---|---|
| primitive reticular cell | A cell with processes making contact with those of other similar cell's to form a cellular network; along with the network of reticular fibres, the reticular cell's form the stroma of bone marrow and lymphatic tissues. (05 Mar 2000) |
| primitive ridge | One of the paired ridge's on either side of the primitive groove. (05 Mar 2000) |
| primitive streak | An ectodermal ridge in the midline at the caudal end of the embryonic disk from which arises the intraembryonic mesoderm; achieved by inward and then lateral migration of cells; in human embryos, it appears on day 15 and gives a cephalocaudal axis to the developing embryo. Synonym: germinal streak. (05 Mar 2000) |
| neuroectodermal tumour, primitive | A malignant brain tumour sharing common features and biologic properties with medulloblastoma. Some pathologists and clinicians use the terms interchangeably: they both can disseminate throughout the nervous system and, in some cases, systemically. most lesions arise from the posterior fossa in children under five years of age. The tumour often produces hydrocephalus and symptoms of increased intracranial pressure. Papilledema is often present. (12 Dec 1998) |
| accelerated reaction | A response occurring in a shorter time than expected; the cutaneous manifestations occurring during the period between the second and tenth day following smallpox vaccination; because it is intermediate between a primary reaction and an immediate reaction, it is regarded as evidence of some degree of resistance. Synonym: vaccinoid reaction. (05 Mar 2000) |
| acid reaction | Any test by which an acid reaction is recognised such as the change of blue litmus paper to red, an excess of hydrogen ions over hydroxide ions in aqueous solution indicated by a pH value less than 7 (at 22캜). Compare: dissociation constant of water. (05 Mar 2000) |
| acute-phase reaction | <immunology, rheumatology> Refers to the changes in synthesis of certain proteins within the serum during an inflammatory response, which provides rapid protection for the host against microorganisms via non-specific defense mechanisms. It consists of fever, an increase in inflammatory humoral factors, and an increased synthesis by hepatocytes of a number of proteins or glycoproteins usually found in the plasma; the reaction is mediated by endogenous pyrogens, the hypothalamus, adrenal hormones, and other factors. (12 Jul 2000) |
| acute situational reaction | An acute emotional reaction related to extreme environmental stress. Synonym: acute situational reaction. (05 Mar 2000) |
| acute stress reaction | A sudden bout of anxiety that is often accompanied by the features of hyperventilation (tingling around mouth and in fingertips, rapid breathing, faintness or fainting). (27 Sep 1997) |
| addition reaction | <chemistry> Any reaction in which two chemicals combine to form a single chemical. (15 Jan 1998) |
| adverse drug reaction reporting systems | Systems developed for collecting reports from government agencies, manufacturers, hospitals, physicians, and other sources on adverse drug reactions. (12 Dec 1998) |
| adverse reaction | Any undesirable or unwanted consequence of a preventive, diagnostic, or therapeutic procedure or regimen. (05 Mar 2000) |
| agar-gel reaction | <immunology> The reaction between an antibody and an antigen during an immunology lab procedure where the two are allowed to diffuse toward each other through an agar-gel medium. Lines of precipitation form in the places on the gel where the two react with each other and shows where the reaction has occurred. (09 Oct 1997) |
| alarm reaction | The various phenomena, e.g., stimulated endocrine activity, which the body exhibits as an adaptive response to injury or stress; first phase of the general adaptation syndrome. (05 Mar 2000) |