| unstable cervical spine fractures | <radiology> Flexion: bilateral interfacetal dislocation, flexion teardrop fracture (usually C5 or C6) extension: extension teardrop fracture (usually C2 or C3), hangman's fracture, extension-dislocation, extension-fracture-dislocation, odontoid fracture vertical compression: Jefferson burst fracture see: cervical spine fractures (12 Dec 1998) |
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| unstable colloid | A colloid that is not again soluble in water after having been dried at ordinary temperature. Synonym: unstable colloid. (05 Mar 2000) |
| unstable fracture | A fracture with an intrinsic tendency to slip out of place after reduction. (05 Mar 2000) |
| unstable haemoglobins | A group of rare Hb's with amino acid substitutions (or amino acid deletions in three types) that alter the three-dimensional shape of the globin in a manner that renders the molecule unstable; they have an increased but variable tendency to auto-oxidation and Heinz body formation and are associated with congenital nonspherocytic haemolytic anaemia. The unstable b chain abnormalities include Hb's Genova, Gun Hill, Hammersmith, Koln, Philly, Sabine, Santa Ana, Sydney, Wien, and Zurich; unstable a chain abnormalities include Hb's Bibba, Sinai, and Torino. (05 Mar 2000) |
| unstable mutation | <molecular biology> A mutation that has a high likelihood of reverting to its original form. (13 Nov 1997) |
| unstable patient | The distinction of stability is made by a physician and based on a large number of variables: patient diagnosis, vital signs, physical findings, laboratory findings, subjective factors and patient prognosis. (27 Sep 1997) |
| ABO haemolytic disease of the newborn | Erythroblastosis foetalis due to maternal-foetal incompatibility with respect to an antigen of the ABO blood group; the foetus possesses A or B antigen which is lacking in the mother, and the mother produces immune antibody which causes haemolysis of foetal erythrocytes. (05 Mar 2000) |
| acquired haemolytic icterus | Icterus and anaemia occuring in association with a moderate degree of splenomegaly, increased fragility of red blood cells, and increased amounts of urobilin in the urine. Synonym: icteroanaemia. Origin: G. Ikteros (05 Mar 2000) |
| beta-haemolytic streptococci | Those that produce active haemolysins (O and S) which cause a zone of clear haemolysis on the blood agar medium in the area of the colony; beta-haemolytic streptococci are divided into groups (A to O) on the basis of cell wall C carbohydrate (see Lancefield classification); Group A (in the strains pathogenic for man) comprises more than 50 types (designated by Arabic numerals) determined by cell wall M protein, which seems to be associated closely with virulence and is produced chiefly by strains with matt or mucoid colonies, in contrast to nonvirulent, glossy colony-producing strains; other surface protein antigens such as R and T (T substance), and the nucleoprotein fraction (P substance) seem to be of less importance. The more than 20 extracellular substances elaborated by strains of beta-haemolytic streptococci include erythrogenic toxin (elaborated only by lysogenic strains), deoxyribonuclease (streptodornase), haemolysins (streptolysins O and S), hyaluronidase, and streptokinase. Synonym: haemolytic streptococci. (05 Mar 2000) |
| complement haemolytic activity assay | Usual screening assay for complement. Dilutions of the serum to be tested are added to antibody-coated erythrocytes and the percentage of lysis is measured. The values are expressed by ch50, haemolytic complement units per milliliter, which is the dilution of serum required to lyse 50 percent of the erythrocytes in the assay. (12 Dec 1998) |
| congenital haemolytic icterus | <haematology> A hereditary disorder that leads to a chronic haemolytic anaemia due to an abnormality in the red blood cell membrane. This disorder is caused by a defective gene. Red cells are resistant to stress and rupture easily. Infants may appear jaundiced and pale. Fatigue, weakness and shortness of breath are other symptoms that may be seen in older patients. The spleen may also be enlarged. Treatment includes splenectomy (removal of the spleen). After this is accomplished the life-span of the red blood cells returns to normal. (27 Sep 1997) |
| congenital haemolytic jaundice | <haematology> A hereditary disorder that leads to a chronic haemolytic anaemia due to an abnormality in the red blood cell membrane. This disorder is caused by a defective gene. Red cells are resistant to stress and rupture easily. Infants may appear jaundiced and pale. Fatigue, weakness and shortness of breath are other symptoms that may be seen in older patients. The spleen may also be enlarged. Treatment includes splenectomy (removal of the spleen). After this is accomplished the life-span of the red blood cells returns to normal. (27 Sep 1997) |
| haemolytic | Destructive to blood cells, resulting in liberation of haemoglobin. Synonym: haematolytic, haemotoxic, haematotoxic, haematoxic. (05 Mar 2000) |
| haemolytic chain | The haemolysis that occurs when complement is activated by the previously formed union of erythrocytes and specific antibody. (05 Mar 2000) |
| haemolytic disease of newborn | <haematology> A condition which develops in the foetus due to an incompatibility between the mother's blood type (RH factor) and the baby's. Maternal antibodies, which enter the foetal circulation during delivery attack the baby's red blood cells leading to haemolysis (rupture of the cells). Symptoms include an infant with an enlarged liver and spleen, swelling, jaundice and anaemia. (27 Sep 1997) |