Comparación entre 2 sistemas analíticos para la determinación de la hemoglobina A1c: inmunoturbidimetría versus cromatografía líquida de alta eficiencia / Comparison of 2 analytical systems for hemoglobin A1c: An immunoturbidimetric method versus high performance liquid chromatography

Introducción. La hemoglobina A1c (HbA1c) es ampliamente utilizada en la determinación del estado glucémico de pacientes con diabetes mellitus. El objetivo de este estudio fue comparar 2 métodos automatizados para medir HbA1c basados en diferentes principios de medida, evaluar la correlación entre ambos y su practicabilidad. Métodos. Se analizaron 622 muestras mediante 2 sistemas analíticos con fundamentos diferentes de medición: cromatografía líquida de alta eficiencia (HPLC) (analizador ADAMS A1c HA-8160; A. Menarini Diagnostics, Italia) e inmunoturbidimetría (Tina-quant Hemoglobin A1c Gen.3, plataforma Cobas 6000; Roche Diagnostics, Suiza). Ambos métodos fueron calibrados según el procedimiento de referencia de la IFCC. Se valoró la correlación entre ambos métodos mediante los análisis de regresión de mínimos cuadrados y Passing-Bablok (R programa v.2.11.1). También se registró el tiempo de puesta en marcha, las tareas de mantenimiento diario y el rendimiento de los 2 instrumentos. Resultados. La correlación fue muy alta tanto por mínimos cuadrados (ordenada en el origen 0.05, pendiente 0.98) como en Passing-Bablok (ordenada en el origen 0,10, pendiente 1,00). El tiempo invertido diariamente para la puesta en marcha del analizador HA-8160 fue de 25 min y el tiempo de finalización fue de 15 min. Las tareas de mantenimiento del Cobas 6000 al inicio y fin del día son procesos automatizados. El rendimiento de los analizadores fue 20 muestras/h en el HA-8160 y 100 muestras/h en el Cobas 6000. El sistema analítico cuyo principio de medida es HPLC incluye también el análisis manual de cada cromatograma. Conclusiones. Existe una correlación excelente entre los métodos de HPLC e inmunoturbidimétrico. La ventaja del sistema analítico que utiliza la inmunoturbidimetría es la optimización del tiempo de procesamiento de las determinaciones de HbA1c, lo que reduce el coste unitario de la prueba (AU)

Introduction. Hemoglobin A1c (HbA1c) is widely used to assess glycemic status in patients with diabetes mellitus. The purpose of this study was to compare 2 automated analytical systems to measure HbA1c that use different measurement principles, evaluating the correlation between the two methods, as well as their ease of use. Methods. A total of 622 samples were analyzed using 2 methods: high performance liquid chromatography (HPLC) (analyzer ADAMS A1c HA-8160; A. Menarini Diagnostics, Italy) and an immunoturbidimetric assay (Tina-quant Hemoglobin A1c Gen.3, Cobas 6000 analyzer; Roche Diagnostics, Switzerland). Both methods were calibrated in accordance with IFCC reference measurement procedure. The correlation between the two methods was assessed by least squares and Passing-Bablok linear regression analyses (R program v.2.11.1). The daily start-up time of the 2 instruments used, daily maintenance tasks, and determination of throughput were also recorded. Results. There was a strong correlation between the results generated by the two test methods using both the least squares (intercept 0.54; slope 0.98) and Passing-Bablok (intercept 0.10; slope 1.00) regression methods. The time spent daily for the start-up of the HA-8160 analyzer was 25 min and completion time was 15 min. Maintenance tasks for the Cobas 6000 analyzer at the beginning and end of the day are automated processes. The throughput for the HA-8160 analyzer was 20 samples/h, and 100 samples/h for the Cobas 6000 analyzer. The HPLC method also included a time-consuming manual analysis of each chromatogram. Conclusions. An excellent correlation was observed between the HPLC and immunoturbidimetric methods. The advantages of the immunoturbidimetric method are optimization of processing time of HbA1c tests and a reduction in the unit cost per test (AU)

Advances in nephelometry through the Ecotech Aurora nephelometer.

The challenge for instrument manufacturers is to continuously improve and evolve their instrumentation to keep pace with scientific research. One field where this is evident is atmospheric aerosol research. The variety in aerosol size, shape, chemical composition, and their ability to change properties under varying atmospheric conditions creates many challenges in quantifying their impact on the global energy balance. As such a wide variety of instrumentation from a selection of manufacturers are used for analysing aerosols, all of which provide a little extra information for deciphering the puzzle. Recent advancements in commercial nephelometers by Australian manufacturer Ecotech have helped to piece some more of this puzzle together. This paper will detail these advances.

Molecular imaging with optics: primer and case for near-infrared fluorescence techniques in personalized medicine.

We compare and contrast the development of optical molecular imaging techniques with nuclear medicine with a didactic emphasis for initiating readers into the field of molecular imaging. The nuclear imaging techniques of gamma scintigraphy, single-photon emission computed tomography, and positron emission tomography are first briefly reviewed. The molecular optical imaging techniques of bioluminescence and fluorescence using gene reporter/probes and gene reporters are described prior to introducing the governing factors of autofluorescence and excitation light leakage. The use of dual-labeled, near-infrared excitable and radio-labeled agents are described with comparative measurements between planar fluorescence and nuclear molecular imaging. The concept of time-independent and -dependent measurements is described with emphasis on integrating time-dependent measurements made in the frequency domain for 3-D tomography. Finally, we comment on the challenges and progress for translating near-infrared (NIR) molecular imaging agents for personalized medicine.

Interferencia en la medida inmunoturbidimétrica de antiestreptolisina-O por un componente monoclonal IgM-kappa en 3 pacientes / Interference in the immunoturbidimetric assay of antistreptolysin-O by monoclonal IgM-Kappa in 3 patients

El hallazgo casual de resultados discrepantes en la determinación de un parámetro bioquímico cuando se realiza en distintas diluciones de la misma muestra, puede orientar hacia una interferencia analítica. Se presenta el estudio de 3 pacientes en los que se demostró una interferencia positiva en la medida inmunoturbidimétrica de antiestreptolisina-O debido a la presencia de una inmunoglobulina monoclonal IgM-k(AU)

The casual finding of disparate results in the determination of an analyte when it is measured at different dilutions on the same sample can lead us to suspect the presence of analytical interference. We present the study of 3 patients in whom a positive interference was proved on the immunoturbidimetric measurement of antistreptolysin-O due to the presence of a monoclonal immunoglobulin IgM Kappa(AU)

Evaluación de un método inmunonefelométrico competitivo para la cuantificación de la homocisteína / Evaluation of a competitive immunonephelometric method for the measurement of homocysteine

Introducción y objetivos. La homocisteína se relaciona con enfermedad vascular, alteraciones del estado nutricional y detección de homocistinuria en neonatos, entre otras enfermedades. Debido a la importancia de su determinación, han aparecido diferentes métodos de cuantificación; el objeto de este trabajo es evaluar el método inmunonefelométrico del aparato BN II (Dade Behring). Material y método. Se realizó una comparación entre 2 métodos de cuantificación: el inmunoanálisis competitivo (IMMULITE 2000, DPC) y el análisis nefelométrico (BN II, Dade Behring), para lo cual se compararon los resultados de 74 muestras, además de determinar la imprecisión intraserial, imprecisión interdiaria, el límite de detección, el límite de cuantificación y el valor crítico del método inmunonefelométrico del BN II de Dade Behring. Resultados. La comparación entre ambos métodos mostró una buena correlación entre el inmunoanálisis competitivo, IMMULITE 2000 de DPC y el análisis nefelométrico, BN II de Dade Behring (Y = 1,4825 + 0,8342X). El valor crítico obtenido fue de 5,46 mmol/l y el límite de detección, de 5,77 mmol/l. La imprecisión intraserial fue inferior al 5% (3,65-4,66%). Conclusiones. El análisis nefelométrico (BN II, Dade Behring) ha demostrado cumplir todos los requisitos técnicos necesarios para su validación como método para la determinación de la homocisteína(AU)

Introduction. The homocysteine is associated with vascular diseases, alterations in the nutritional states, homocystinuria detection in neonates, as well as other diseases. Due to the importance of its determination, different measurement methods have been developed. The aim of this work is to evaluate the imunonephelometric method used in the Dade Behring BN II Nephelometer system. Material and method. We present a comparison between 2 methods: a competitive inmunoassay (IMMULITE 2000, DPC) and the nephelometric test (BN II, Dade Behring). For the determination of within batch and between-day imprecision, 74 samples were analysed and compared. Results. The detection and quantification limits, and the critical value of the inmunonephelometric method, were also determined. Both methods showed good correlations (Y = 1.4825 + 0.8342X). We also obtained a critical value of 5.46 mmol/L and the detection limit was 5.77 mmol/L. Within batch imprecision was below 5 % (3.65-4.66%). Conclusions. The nephelometric test (Dade Behring BN II System) has demonstrated to fulfill all the technical requirements needed for its validation as a method for the determination of homocysteine(AU)

Process monitoring using ultrasonic sensor systems.

Continuous in-line measurement of substance concentration in liquid mixtures is valuable in improving industrial processes in terms of material properties, energy efficiency and process safety. Ultrasonic sensor systems meet the practical requirements of a chemical sensor quite well. Currently ultrasonic sensor systems are widely used as acoustic chemical sensors to measure concentration of selected substances or to monitor the course of polymerisation, crystallisation or fermentation processes. Useable acoustic properties for the characterisation of liquid mixtures are sound velocity, sound absorption and acoustic impedance. This contribution will give a short overview of the state of the art and several trends for the use of ultrasonic sensor systems in process applications. Novel investigations show the very promising possibility to analyse liquid multi-phase mixtures like suspensions, emulsions and dispersions.

Analytic performance evaluation of a new turbidimetric immunoassay for carbamazepine on the ADVIA 1650 analyzer: effect of carbamazepine 10,11-epoxide.

Carbamazepine, an anticonvulsant, requires therapeutic drug monitoring. Recently Bayer HealthCare, Diagnostics Division released a turbidimetric immunoassay of carbamazepine on the ADVIA 1650 analyzer. We evaluated the analytic performance of this assay by comparing values obtained with this new assay in sera of 54 patients receiving carbamazepine with the values obtained by using a widely used fluorescence polarization immunoassay (FPIA) and a chemiluminescent immunoassay (CLIA). The new turbidimetric immunoassay for carbamazepine showed excellent precision. The low control showed a total CV of 4.9% (mean 2.86, SD 0.14 microg/mL), the medium control demonstrated a total CV of 3.5% (mean 7.79, SD 0.27 microg/mL), and the high control showed a total CV of 4.8% (mean 16.15, SD 0.78 microg/mL). The assay was linear up to a carbamazepine concentration of 20 microg/mL. The assay showed excellent dilution recovery and recovery of samples supplemented with carbamazepine (mean recovery 102.2%). We observed an excellent correlation between the values obtained by the FPIA (x-axis) assay and the new turbidimetric (y-axis) assay (y = 0.96 x - 0.46, r = 0.99, n = 54). We also observed excellent correlation between the values obtained by the CLIA (x-axis) and the turbidimetric (y-axis) assay (y = 1.10 x -0.32, r = 0.99, n = 54). However, the slope of 1.10 was higher than the slope of 0.96 observed with the regression equation obtained by using values obtained by the FPIA and the turbidimetric assay. The positive bias obtained with the new turbidimetric assay compared with the CLIA assay resulted from lower cross reactivity of carbamazepine 10,11-epoxide, the active metabolite of carbamazepine, with CLIA. On the other hand, the cross reactivity of the metabolite is similar between the new turbidimetric assay and the FPIA assay. We conclude that the new turbidimetric assay can be used for routine monitoring of carbamazepine in clinical laboratories.

Comparación de tres métodos cuantitativos para la determinación de proteínas totales en orina / A comparison of three methods for quantitative determination of total urine protein

Ante la falta de un método de referencia para la cuantificación de proteínas en orina, el objetivo de este trabajo es comparar las distintas metodologías existentes en nuestro Hospital. En nuestro Hospital las muestras con petición de análisis sistemático de orina son analizadas mediante un método semi-cuantitativo de tira reactiva y, en caso de resultado positivo, se efectúa su cuantificación por turbidimetría en el Laboratorio Central y en el Laboratorio de Urgencias por una metodología de unión a colorantes. Además, la determinación de proteínas especificas (albúmina, transferrina e inmunoglobulina G) se realiza mediante nefelometría cinética. En nuestro estudio hemos determinado proteínas totales en 103 muestras de orina positivas en la tira reactiva. Para la comparación de métodos se ha considerado como el más cercano al de referencia el de unión a colorantes. Los resultados obtenidos han sido discrepantes con diferencias constantes y proporcionales y coeficientes de correlación no superiores a 0,8. El conocimiento de estas diferencias nos lleva a la necesidad de profundizar en casos clínicos (AU)

Several methodologies for determination of total urine protein are frequently used in a Clinical Chemistry Laboratory this problem, increased by the lack of an established reference method, could induce confusion in both analysts and clinicians. In this study, urine samples with a positive result for total protein by an automated test strip were analyzed by a quantitative turbidimetric method and by a quantitative dye-binding essay in routine and urgent work, respectively. By the other way, albumin, transferrin and immunoglobulin G were quantified in the same specimens using a cinetic nephelometry method. All protein determinations were performed in 103 consecutive urine sample. The Kodak 250 essay [a dye-binding based assay] was considered as 'gold standard' for method comparison. Statistical differences were found for both y-intercept and siope in regression analysis [Hitachi 917 vs Kodak 250, and Immage vs Kodak 250). The correlation coefficients [r] values were less than 0.8. The knowledge of these differences should carry out to perform alternative methodologies when discrepant/unexpected values were obtained or when further clinical study was necessary (AU)

Rapid monitoring of recombinant protein products: a comparison of current technologies.

Specific measurement of recombinant protein titer in a complex environment during industrial bioprocessing has traditionally relied on labor-intensive and time-consuming immunoassays. In recent years, however, developments in analytical technology have resulted in improved methods for protein product monitoring during bioprocessing. The choice of product-monitoring technology for a particular bioprocess will depend on a variety of assay factors and instrument-specific factors. In this article, we have compiled an overview of the advantages and disadvantages of the most commonly used technologies used: electrochemiluminescence, optical biosensors, rapid chromatography and nephelometry. The advantages of each technology for measuring both small and large recombinant therapeutic proteins are compared with a conventional enzyme-linked immunosorbent assay (ELISA) technique.

[New methods and equipment for studying the hemostatic system (review of the literature)]. / Novye sposoby i ustroistva dlia issledovaniia sistemy gemostaza (obzor literatury).

The author analyzes the principles and reviews the ranges of application of conductometric, filtration rapid method for studies of formed element aggregation in stabilized blood, hemostographic, photodynamic method for blood clotting registration, superfusion method for assessment of hemocoagulation tissue factor release reaction. He comes to a conclusion that the diagnosis may become objective, rapid, reliable, and accurate if biophysical characteristics of the hemostasis are investigated, their informative value assessed, and measuring equipment for hematologic laboratories designed and commercially produced.