Automated determination of anti-streptolysin O antibodies by a kinetic hemolytic method.

An automated method which uses oxidized Streptolysin O and determines the anti-Streptolysin O titer in whole blood without dilution of the sample is described. The addition of a reducing agent starts the hemolysis at an initial rate which is inversely proportional to the anti-Streptolysin O titer of the sample. An instrument (Taso-matic), designed to automatically execute all of the procedures, was used. Comparison between the described method and the classical hemolytic method gave the following linear regression slope y = 1.06x-13 (r = 0.974). Precision of the method at two different anti-Streptolysin O titers (200 and 500 IU), expressed as relative standard deviation, was 12.1 and 4.7% in the between-run procedure and 10.1 and 4.9% in the within-run procedure, respectively.

The 4-hydroxybenzoate/4-aminophenazone chromogenic system used in the enzymic determination of serum cholesterol.

A single reagent, containing cholesterol oxidase, cholesterol esterase, peroxidase, 4-hydroxybenzoate, and 4-aminophenazone, is used in determining serum cholesterol. Analysis time is 15 min, and the standard curve is linear to 6.0 g/liter. Analytical recovery of cholesterol was 100.1 +/- 0.4%. Within-run precision (CV) was less than or equal to 1.4 1.4%, between-run less than or equal to 4.8%. Comparison with results by a Liebermann Burchard method [Clin. Chim. Acta 5, 637 (1960)] gave a linear regression of y = 1.08x--0.05, with a correlation coefficient (r) of 0.985. Comparison with the Roeschlau enzymic method [J. Clin. Chem. Clin. Biochem, 12, 226 (1974)] gave y = 1.02x + 0.01 (r = 0.958). Comparison with the enzymic method of Allain et al. [Clin. Chem. 20, 470 (1974)] gave y = 1.01x--0.00 (r = 0.995). The following substances do not interfere up to the indicated concentrations (mg/liter): hemoglobin (5000), bilirubin (100), reduced glutathione (150), l-cysteine (400), urea (3000), creatinine (200), uric acid (200), d-glucose (10000), L-ascorbic acid (50), acetylsalicylic acid (500), L-DOPA (10), ergothioneine (1000), 2,5-dihydroxybenzoic acid (20), and 3,4-dihydroxybenzoic acid (10). Stored in an amber-colored bottle, the working reagent is stable for three months at 2--8 degrees C and for three weeks at 25 degrees C.

Adenylate kinase inhibition by adenosine 5'-monophosphate and fluoride in the determination of creatine kinase activity.

The current methods for the determination of creatine kinase (EC 2.7.3.2) activity are derived from Oliver's method, in which AMP is used to decrease interference by adenylate kinase (EC 2.7.4.3). Recently, Szasz et al. and Rosano et al. described methods in which diadenosine pentaphosphate and fluoride, respectively, are used to reduce this interference. However, diadenosine pentaphosphate does not sufficiently inhibit such activity of hepatic origin, while fluoride alone can only inhibit it at concentrations at which the fluoride tends to precipitate as MgF2. Finally, Szasz et al., the Committee on Enzymes of the Scandinavian Society for Clinical Chemistry and Clinical Physiology, and the German Society for Clinical Chemistry have proposed methods in which both AMP and diadenosine pentaphosphate are used to inhibit adenylate kinase. We have found that by using low concentrations of AMP and fluoride together, we can greatly diminish this interference without significant loss of creatine kinase activity and with no precipitation of MgF2.

[Results of 2 quality control programs performed in Tuscany in the year 1973 and 1974]. / Risultati di due programmi di controllo di qualità effettuati in Toscana nel 1973 e nel 1974

Here after are reported all the results obtained from an interlaboratory quality control program performed in Tuscany in 1973 and in 1974. In 1973, 35 hospital laboratories partecipated to the program, while in 1974 the partecipating laboratories were 79: hospital's, private's and of public bodies. The results obtained in the program performed in 1974 were less satisfactory of those obtained in 1973 and showed the need of repeating such programs in order to improve the operating efficiency of laboratories.