Measurement of total and free prostate specific antigen (PSA) in human serum samples using an ultra-microanalytical system.

Prostate specific antigen (PSA) is a serine protease used for the screening of prostate cancer. The total portion of PSA (tPSA) can be found in its free form (fPSA), or bound to other proteins forming a stable complex. A heterogeneous sandwich-type UltraMicro Enzyme-Linked ImmunoSorbent Assay (UMELISA) has been developed for the measurement of tPSA and fPSA in human serum samples. Strips coated with a high affinity monoclonal antibody (MAb) directed against PSA are used as solid phase, to ensure the specificity of the assay. Biotinylated MAbs specific for tPSA and fPSA ensured sensitivity, given the high affinity binding to streptavidin. The assay was completed in 1.5 h, with a measuring range 0.019-20 µg/L (tPSA), and 0.009-20 µg/L (fPSA). The intra- and inter-assay CV were lower than 9%. Recovery percentages were 96-105%. High correlations were found between the values of the UMELISA PSA standards and the International Reference Standards 96/670 (R2 = 0.9996) and 96/688 (R2 = 0.9989). The assay did not recognize any of the interfering molecules tested. Regression analysis of serum samples showed a good correlation with Roche Elecsys total PSA (n = 631, R2 = 0.986, ρc = 0.992), BioMérieux VIDAS TPSA (n = 631, R2 = 0.989, ρc = 0.993) and Roche Elecsys free PSA (n = 164, R2 = 0.973, ρc = 0.979), all with a relative difference below 15%, and a p < 0.001. A retrospective study of the use of UMELISA PSA in Cuba was carried out. The analytical performance characteristics of UMELISA PSA support its use for the quantification of tPSA and fPSA in human serum samples in a single kit, making it an affordable diagnostic assay available to Cuban Public Health System and developing countries. Between the years 2014-2020, more than 3 million Cuban patients have benefited from the test for free.

SUMA Technology and Newborn Screening Tests for Inherited Metabolic Diseases in Cuba: An Overview of the First 30 Years

Abstract The ultramicroanalytic system (SUMA), created in the 1980s, is a complete system of reagents and instrumentation to perform ultramicroassays combining the sensitivity of the micro-enzyme-linked immunosorbent assay (ELISA) tests with the use of ultramicrovolumes. This technology permitted establishing large-scale newborn screening programs (NSPs) for metabolic and endocrine disorders in Cuba. This article summarizes the main results of the implementation during the 30 years of SUMA technology in NSP for 5 inherited metabolic diseases, using ultramicroassays developed at the Department of Newborn Screening at the Immunoassay Center. Since 1986, SUMA technology has been used in the Cuban NSP for congenital hypothyroidism, initially studying thyroid hormone in cord serum samples. In 2000, a decentralized program for the detection of hyperphenylalaninemias using heel dried blood samples was initiated. These successful experiences permitted including protocols for screening congenital adrenal hyperplasia, galactosemia, and biotinidase deficiency in 2005. A program for the newborn screening of CH using the thyroid-stimulating hormone Neonatal ultramicro-ELISA was fully implemented in 2010. Nowadays, the NSP is supported by a network of 175 SUMA laboratories. After 30 years, more than 3.8 million Cuban newborns have been screened, and 1002 affected children have been detected. Moreover, SUMA technology has been presented in Latin America for over 2 decades and has contributed to screen around 17 million newborns. These results prove that developing countries can develop appropriate diagnostic technologies for making health care accessible to all.

Programa nacional de detección precoz de hipotiroidismo congénito: Cuba, 1988 / National program for early detection of congenital hypothyroidism: Cuba, 1988

Nuestro grupo ha desarrollado un método de ultramicro ELISA para la determinación de TSH en suero denominado sandwich, el cual nos ha permitido la implantación de un Programa Nacional de Detección de Hipotiroidismo Congénito, a partir de mayo de 1986. La técnica es sensible, simple, económica, con alto grado de automatización, se usa un sistema ultraanalítico (SUMA, patente cubana). Desde esa fecha hasta diciembre de 1988 se han estudiado 183 804 recién nacidos, se utiliza sangre del cordón umbilical para la determinación de TSH, se han detectado 76 hipotiroideos para una frecuencia de 1 en 2 418. Se han reevaluado 3 224 (1,7 %), por presentar TSH > 25 m U/L. No hemos conocido de falsos negativos. Desde el punto de vista neuropsíquico se realizan dos estrategias: evaluación e intervención con el fin de mejorar el desarrollo neuropsíquico, los resultados preliminares en este aspecto confirman la eficiencia del programa. Se analiza la relación costo/beneficio de nuestro programa y se recomienda su metodología como proceder de elección en los programas masivos de pesquizaje de hipotiroidismo congénito

Programa nacional de detección precoz de hipotiroidismo congénito. Cuba, 1988 / National program for early detection of congenital hypothyroidism: Cuba, 1988

Nuestro grupo ha desarrollado un método de ultramicro ELISA para la determinación de TSH en suero denominado sandwich, el cual nos ha permitido la implantación de un Programa Nacional de Detección de Hipotiroidismo Congénito, a partir de mayo de 1986. La técnica es sensible, simple, económica, con alto grado de automatización, se usa un sistema ultraanalítico (SUMA, patente cubana). Desde esa fecha hasta diciembre de 1988 se han estudiado 183 804 recién nacidos, se utiliza sangre del cordón umbilical para la determinación de TSH, se han detectado 76 hipotiroideos para una frecuencia de 1 en 2 418. Se han reevaluado 3 224 (1,7 ), por presentar TSH > 25 m U/L. No hemos conocido de falsos negativos. Desde el punto de vista neuropsíquico se realizan dos estrategias: evaluación e intervención con el fin de mejorar el desarrollo neuropsíquico, los resultados preliminares en este aspecto confirman la eficiencia del programa. Se analiza la relación costo/beneficio de nuestro programa y se recomienda su metodología como proceder de elección en los programas masivos de pesquizaje de hipotiroidismo congénito