An enzyme immunoassay for determining albumin in human urine samples using an ultra-microanalytical system.

Microalbuminuria is a term to describe a moderate increase in the level of albumin in urine. It is an important prognostic marker for kidney damage in diseases such as diabetes mellitus and hypertension. A simple sandwich-type ultramicroELISA assay (UMELISA) has been developed for the measurement of albumin in human urine samples. Strips coated with a high affinity monoclonal antibody directed against albumin are used as solid phase, to ensure the specificity of the assay. The albumin assay was completed in 1 hr and 30 min, with a measuring range of 1.44-200 ng/mL. The intra- and inter-assay coefficients of variation were 3.98-4.35% and 7.59-8.92%, respectively, depending on the albumin concentrations evaluated. Percentage recovery ranged from 94.26 to 98.50%. Regression analysis showed a good correlation with the commercial quantitative turbidimetric test Microalbumin-turbilatex (n = 240, r = 0.994, p < .01). The analytical performance characteristics of our UMELISA MICROALBUMINA endorse its use for the quantification of albumin in human urine samples. This test will make a cost-effective diagnostic kit accessible to low-income countries such as Latin American countries and is now available in the Cuban Public Health System.

An enzyme immunoassay for determining epidermal growth factor (EGF) in human serum samples using an ultramicroanalytical system.

Human epidermal growth factor is a small peptide consisting of 53 amino acid residues, which stimulates cell proliferation and is associated with several human carcinomas. A simple sandwich-type ultramicroELISA assay (UMELISA), based on the advantages of high affinity reaction between streptavidin and biotin has been developed for the measurement of EGF in human serum samples. Strips coated with a high affinity monoclonal antibody directed against EGF are used as solid phase, to ensure the specificity of the assay. The EGF assay was completed in 18 hr, with a measuring range of 39-2500 pg/mL. The intra- and inter-assay coefficients of variation were 4.4-7.3% and 0-5.1%, respectively, depending on the EGF concentrations evaluated. Percentage recovery ranged from 96-104%. Regression analysis showed a good correlation with the commercially available Human EGF Immunoassay Quantikine® ELISA kit (n = 130, r = 0.92, P < 0.01). The analytical performance characteristics of our UMELISA EGF endorse its use for the quantification of EGF in human serum samples.