Journal of the International Federation of Clinical Chemistry最新文献

Ultrasensitive bioluminescence immunoassays for the determination of peptides and proteins are illustrated in this paper with the enzyme immunological determination of total IgE in human serum. The usable range of standard curves is from 5 pg to 5000 pg per liter. The intra- and interassay coefficients of variation of this test are in the same range as obtained for chromogenic enzyme immunoassays.

All biomedical assays have certain aspects in common, the most striking of which is that they generally involve protein-binding. Ligand-ligator interactions and the resulting response form the basis of most assays. This paper reviews the advantages and limitations of different types of assays ranging from long-term bioassays to in vitro assays using cell-free components. Consideration of these aspects helps in the understanding of the different assays, selection of appropriate assays for different applications, and the better interpretation of assay results. Clinical chemists, hematologists, endocrinologists, immunologists, and scientists from other disciplines have each developed their own measurement methods and units. This paper seeks to identify those aspects and principles common to assays in all such disciplines, concentrating on protein-binding systems. Understanding what and how different assays measure may clarify why different assay methods often give different results.

Different diagnostic applications are discussed for various categories of repetitive DNA sequences. Since all eukaryotes are characterized by genomic redundancy, these sensitive, rapid, and comparatively simple techniques are revolutionizing many fields in clinical and experimental diagnostics. In addition to individuality testing in humans and animals, for example, eukaryotic infectious agents can be identified and tumors classified with respect to genomic changes. The forensic as well as animal and plant breeding sciences have already adopted the DNA technology involving repetitive sequence tools.

The substance concentration of ionized calcium (cCa 2+) in blood, plasma, or serum preanalytically may be affected by pH changes of the sample, calcium binding by heparin, and dilution by the anticoagulant solution. pH changes in whole blood can be minimized by anaerobic sampling to avoid loss of CO 2, by measuring as soon as possible, or by storing the sample in iced water to avoid lactic acid formation. cCa 2+ and pH should be determined simultaneously. Plasma or serum: If centrifuged in a closed tube and measured immediately, the pH of the sample will be close to the original value. If there has been a delay between centrifugation and measurement, causing substantial loss of CO 2, equilibration of the sample with a gas mixture corresponding to pCO 2 = 5.3 kPa prior to the measurement is recommended. Conversion of the measured values to cCa 2+ (7.4) is only valid if the pH is in the range 7.2-7.6. Ca 2+ binding by heparin can be minimized by using either of the following: 1) a final concentration of sodium or lithium heparinate of 15 IU/mL blood or less; or 2) calcium-titrated heparin with a final concentration of less than 50 IU/mL blood. Dilution effect can be avoided by use of dry heparin in capillaries or syringes.(ABSTRACT TRUNCATED AT 250 WORDS)

The accuracy and precision of the Packard Probe 1000, a computer-driven robotic sample processor, were determined using NCCLS Guideline 18-P, employing a rigorous gravimetric procedure. For volumes of 25, 100, and 200 muL, inaccuracy ranged from -0.5 to +0.6% (saline) and -0.8 to +0.7% (human serum), and imprecision from 0.1 to 0.6% (saline) and 0.02 to 0.8% (human serum), in the dip and sip mode of pipetting. For the same volumes of saline in the dispense-through pipetting mode, inaccuracy ranged from -0.1 to -0.9% and imprecision from 0.1 to 0.5%. To obtain this level of performance, the instrument's operating parameters were changed from the factory default settings. This automated liquid-handling system is capable of impressive accuracy and precision, but it must be calibrated in the same manner as any other volumetric device. Performance varies with the volume, type of liquid, and mode of pipetting. Inaccuracy of less than or equal to 1.0% and imprecision of less than =1.0% can be attained along with rapid, walkaway pipetting of calibrators, controls, and large numbers of patient samples.