Assessment of Biological Reagents for Presence of Human Immunodeficiency Virus-1 (HIV-1) Antigens

Peer Reviewe

Gas-Chromatographic Determination of Ethylene Glycol in Serum

Abstract We have developed a method for detection and quantitation of ethylene glycol in serum, based on the gas chromatography of its dibenzoate ester. No special reagents or equipment are required. The method is virtually free of interference and sensitive to less than 0.02 mg of ethylene glycol per milliliter. The total analysis time is about 90 min.</jats:p

Effect of arylsulfatase A and sialidase on the biochemical and immunological properties of creatine kinase isoenzyme BB.

Abstract This work describes the action of the lysosomal enzymes arylsulfatase A (EC 3.1.6.1) and sialidase (EC 3.2.1.18) on human creatine kinase (CK, EC 2.7.3.2) isoenzyme BB. The isoenzyme, which gives a positive reaction with the periodic acid-Schiff reagent, contains 12 molecules of sulfate and two molecules of sialic acid per molecule. On treatment with arylsulfatase, CK-BB lost enzyme activity but retained immunoreactivity, its isoelectric point was altered, and it was partly bound to a "Glyco-gel" affinity column. On treatment with sialidase, the isoenzyme lost activity, its immunoreactivity was decreased by 70%, and the inactivated CK-BB would not bind to either "Glyco-gel" or concanavalin A. We propose that the sulfate groups are involved in maintaining the integrity of the active site of the enzyme but are not involved in antigenic recognition sites on the molecule. Sialic acid plays an important role in both the structural pattern of the antigenic determinant and the active site of CK-BB.</jats:p

Thyrotropin as measured by a sensitive immunoradiometric assay.

Abstract An immunoradiometric assay (Boots-Celltech's "Sucrosep"; IRMA) for thyrotropin (TSH) was evaluated and results were compared with those of our in-house RIA procedure. The IRMA had a sensitivity of 0.02 milli-int. unit/L. In addition it displayed excellent intra- and inter-batch precision, cross-reacted negligibly with other pituitary hormones, and appeared to be relatively free of matrix effects (although deionized water did give an apparent TSH concentration of 0.13 milli-int. unit/L). Over the range 1.2 to 64 milli-int. units/L, correlation between the IRMA (y) and RIA (x) was excellent: y = 1.16x - 1.69 (r = 0.98). The normal reference interval for the IRMA was 0.4 to 4.2 milli-int. units/L. For patients suspected of hyperthyroidism who had been subjected to the thyroliberin test, the IRMA more effectively differentiated between euthyroidism and hyperthyroidism. During testing with thyroliberin, all nonresponding hyperthyroid patients had initial baseline TSH concentrations of less than 0.02 milli-int. unit/L by IRMA. This sensitive assay represents an important advance in the ability to differentiate between euthyroidism and hyperthyroidism.</jats:p

Are Clinical Laboratory Proficiency Tests as good as They Can Be?

Abstract Present proficiency test services that use the peer group mean and statistically derived ranges of acceptability are not serving us optimally and are even counterproductive in some respects. We recommend that the target value be determined by a widely accepted reference method and that acceptable ranges be based on criteria related to clinical need. This approach was adopted several years ago in Germany and has already eliminated the use of several unsatisfactory analytical methods. Because the transition would probably take many years, we propose an interim solution to allow instrument manufacturers and laboratorians to adapt to these changes. The current peer group means and acceptable ranges should be supplemented by reference method values and acceptable ranges, based on clinical need, so that manufacturers and laboratorians can judge their performance against these new criteria and make the necessary adjustment in instrumentation and methodology. These processes should be paralleled by efforts to produce proficiency test materials that will not exhibit the matrix problems of present-day preparations.</jats:p