| Rh null syndrome | <syndrome> A lack of all Rh antigens, compensated haemolytic anaemia, and stomatocytosis. (05 Mar 2000) |
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| null | 1. Something that has no force or meaning. 2. That which has no value; a cipher; zero. <physics> Null method, a zero method. See Zero. Source: Websters Dictionary (01 Mar 1998) |
| null cell | Lymphocytes lacking typical markers of T or B-cells capable of lysing a variety of tumour or virus infected cells without obvious antigenic stimulation, also effect antibody dependent cell cytotoxicity, carry in humans CD16 marker. (18 Nov 1997) |
| null-cell adenoma | <tumour> An adenoma of the hypophysis composed of cells for which there is no overt evidence or hormone production, but which usually produces hypopituitarism and visual disturbances by compression of adjacent structures; approximately one third of these tumours have cells with abundant mitochondria (oncocytes) that are somewhat larger than the monocytic null cells. Synonym: undifferentiated cell adenoma. (05 Mar 2000) |
| null cells | Large granular lymphocytes that lack surface markers/membrane associated proteins of either B or T lymphocytes. (05 Mar 2000) |
| null hypothesis | The assumption that any observed difference between two samples of a statistical population is purely accidental and not due to systematic causes. (05 Dec 1998) |
| null mutation | Change in a gene that leads to nothing, for example to no enzyme or to a nonfunctioning enzyme. (12 Dec 1998) |
| lymphocytes, null | A class of lymphocytes characterised by the lack of surface markers specific for either t or b lymphocytes. (12 Dec 1998) |
| Abbott's method | A method of treatment of scoliosis by use of a series of plaster jackets applied after partial correction of the curvature by external force. (05 Mar 2000) |
| Abell-Kendall method | A standard method for estimation of total serum cholesterol involving saponification of cholesterol ester by hydroxide, extraction with petroleum ether, and colour development with acetic anhydride-sulfuric acid; the method avoids interference by bilirubin, protein, and haemoglobin. (05 Mar 2000) |
| activated sludge method | A method of sewage disposal in which the sewage is treated with 15% bacterially active, liquid sludge, which is produced by repeated vigorous aeration of fresh sewage to form floccules or sediment; when this flocculation process is complete, the resulting activated sludge contains large numbers of bacteria, together with yeasts, molds, and protozoa, which actively effect the oxidation of organic compounds; this mixture is piped to a sedimentation tank, the effluent from which is completely treated sewage. (05 Mar 2000) |
| Altmann-Gersh method | The method of rapidly freezing a tissue and dehydrating it in a vacuum. (05 Mar 2000) |
| Anel's method | Ligation of an artery immediately above (on the proximal side of) an aneurysm. (05 Mar 2000) |
| Antyllus' method | Ligation of the artery above and below an aneurysm, followed by incision into and emptying of the sac. (05 Mar 2000) |
| aristotelian method | A method of study that stresses the relation between a general category and a particular object. (05 Mar 2000) |