Biomaterial Database

International study on the comparability of Apo A-1 and Apo B methods. 1990

D Grafnetter, and E Molinari, and L Lonsky

Institute for Clinical and Experimental Medicine, Prague, Czechaslovakia.

Apo A-1 and Apo B levels have become increasingly important as a mean of assessing risk and susceptibility to cardiovascular diseases. These proteins are measured routinely in numerous clinical and research laboratories due primarily to the ability to mechanise the immunological assay method and to the ready availability of commercially produced antisera and standards which are often sold in kit form. However, if these variables are to be used to assess the clinical risk of disease reliably, the test methods should have a low degree of imprecision and inaccuracy, to reduce false positive and negative results. The 'normal' and 'pathological' ranges for both proteins also need to be clearly defined. In order to be able to define clinical ranges and establish quality control limits on both a national and international level the inaccuracy and imprecision of the different methods used to assay the parameters need to be established. Since the technical expertise and the equipment and reagents used vary between laboratories, and because there is no internationally recognized calibration material, a survey conducted to establish imprecision and inaccuracy must include many laboratories to take these variations into account. At the WHO Collaborating Lipid Reference Centre, The Institute for Clinical and Experimental Medicine in Prague, Czechoslovakia, we have been involved in the external quality control programme for cholesterol, triglyceride, HDL-cholesterol and thiocyanate methods for more than 15 yr. Although the Centre was originally created as a European Reference Centre, laboratories participating in our quality control scheme now come from Asia, the USA and New Zealand as well as Europe due to their involvement in the large scale population studies like 'MONICA', 'ERICA' and 'CINDI'. In addition we also cooperate with some laboratories expected to join WHO projects and with others running either national or their own research programmes. Due to the increasing need to learn more about the methods used for Apo A-1 and Apo B assays in both research and preventive schemes for cardiovascular diseases, we decided, following the combined IUIS and NHLBI-CDC Apolipoprotein standardization surveys, to arrange for an international survey to determine the precision and relative accuracy of EIA, ELISA, INA, TURB and RID methods. Our survey originally intended to include only European laboratories but the number of participants increased (Table I) and we believe it supplies complementary information to the IUIS-NHLBI-CDC surveys because both research and routine clinical laboratories were included in our survey.

UI	MeSH Term	Description	Entries
D009391	Nephelometry and Turbidimetry	Chemical analysis based on the phenomenon whereby light, passing through a medium with dispersed particles of a different refractive index from that of the medium, is attenuated in intensity by scattering. In turbidimetry, the intensity of light transmitted through the medium, the unscattered light, is measured. In nephelometry, the intensity of the scattered light is measured, usually, but not necessarily, at right angles to the incident light beam.	Turbidimetry,Nephelometry,Turbidimetry and Nephelometry
D011863	Radioimmunoassay	Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.	Radioimmunoassays
D012015	Reference Standards	A basis of value established for the measure of quantity, weight, extent or quality, e.g. weight standards, standard solutions, methods, techniques, and procedures used in diagnosis and therapy.	Standard Preparations,Standards, Reference,Preparations, Standard,Standardization,Standards,Preparation, Standard,Reference Standard,Standard Preparation,Standard, Reference
D004586	Electrophoresis	An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current.	Electrophoreses
D004797	Enzyme-Linked Immunosorbent Assay	An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed.	ELISA,Assay, Enzyme-Linked Immunosorbent,Assays, Enzyme-Linked Immunosorbent,Enzyme Linked Immunosorbent Assay,Enzyme-Linked Immunosorbent Assays,Immunosorbent Assay, Enzyme-Linked,Immunosorbent Assays, Enzyme-Linked
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001054	Apolipoproteins A	Structural proteins of the alpha-lipoproteins (HIGH DENSITY LIPOPROTEINS), including APOLIPOPROTEIN A-I and APOLIPOPROTEIN A-II. They can modulate the activity of LECITHIN CHOLESTEROL ACYLTRANSFERASE. These apolipoproteins are low in atherosclerotic patients. They are either absent or present in extremely low plasma concentration in TANGIER DISEASE.	Apo-A,ApoA
D001055	Apolipoproteins B	Major structural proteins of triacylglycerol-rich LIPOPROTEINS. There are two forms, apolipoprotein B-100 and apolipoprotein B-48, both derived from a single gene. ApoB-100 expressed in the liver is found in low-density lipoproteins (LIPOPROTEINS, LDL; LIPOPROTEINS, VLDL). ApoB-48 expressed in the intestine is found in CHYLOMICRONS. They are important in the biosynthesis, transport, and metabolism of triacylglycerol-rich lipoproteins. Plasma Apo-B levels are high in atherosclerotic patients but non-detectable in ABETALIPOPROTEINEMIA.	Apo-B,Apo B,ApoB,Apoprotein (B),Apoproteins B
D016632	Apolipoprotein A-I	The most abundant protein component of HIGH DENSITY LIPOPROTEINS or HDL. This protein serves as an acceptor for CHOLESTEROL released from cells thus promoting efflux of cholesterol to HDL then to the LIVER for excretion from the body (reverse cholesterol transport). It also acts as a cofactor for LECITHIN CHOLESTEROL ACYLTRANSFERASE that forms CHOLESTEROL ESTERS on the HDL particles. Mutations of this gene APOA1 cause HDL deficiency, such as in FAMILIAL ALPHA LIPOPROTEIN DEFICIENCY DISEASE and in some patients with TANGIER DISEASE.	Apo A-I,Apo A-1,Apo A-I Isoproteins,Apo A1,Apo AI,ApoA-1,ApoA-I,Apolipoprotein A-1,Apolipoprotein A-I Isoprotein-2,Apolipoprotein A-I Isoprotein-4,Apolipoprotein A-I Isoproteins,Apolipoprotein A1,Apolipoprotein AI,Apolipoprotein AI Propeptide,Pro-Apo A-I,Pro-Apolipoprotein A-I,Proapolipoprotein AI,Apo A I Isoproteins,Apolipoprotein A 1,Apolipoprotein A I,Apolipoprotein A I Isoprotein 2,Apolipoprotein A I Isoprotein 4,Apolipoprotein A I Isoproteins,Pro Apo A I,Pro Apolipoprotein A I