Development and standardization of solid phase assays for the detection of anti-neutrophil cytoplasmic antibodies (ANCA). A report on the second phase of an international cooperative study on the standardization of ANCA assays

Anti-neutrophil cytoplasmic antibodies (ANCA) are diagnostic markers for systemic vasculitis. They are classically I detected by an indirect immunofluorescence test using normal donor neutrophils as substrate. This assay lacks antigenic specificity and is not quantitative. The 'EC/BCR Project for ANCA Assay Standardization' is an international collaboration study with the aim to develop and standardize solid phase assays for ANCA detection. In this part of the study the isolation and characterization of proteinase-3 and myeloperoxidase, the two main target molecules for ANCA, and the development and standardization of ELISAs with these antigens are described. Six laboratories successfully isolated purified proteinase-3 preparations that could be used. Three of these preparations, together with one myeloperoxidase preparation, were subsequently used for ANCA testing by ELISA. The ELISA technique was standardized in two rounds of testing in the 14 participating laboratories. The coefficient of variation of these new assays decreased from values of approx. 50% in the first round to approx. 20% in the second round. We conclude that purified proteinase-3 and myeloperoxidase can be used in standardized ELISAs for ANCA detection. Whether such procedures offer advantages over the IIF test will be determined in a prospective clinical study.

The HUman MicroNucleus project on eXfoLiated buccal cells (HUMNXL): The role of life-style, host factors, occupational exposures, health status, and assay protocol

The human buccal micronucleus cytome assay (BMCyt) is one of the most widely used techniques to measure genetic damage in human population studies. Reducing protocol variability, assessing the role of confounders, and estimating a range of reference values are research priorities that will be addressed by the HUMNXL, collaborative study. The HUMNXL, project evaluates the impact of host factors, occupation, life-style, disease status, and protocol features on the occurrence of MN in exfoliated buccal cells. In addition, the study will provide a range of reference values for all cytome endpoints. A database of 5424 subjects with buccal MN values obtained from 30 laboratories worldwide was compiled and analyzed to investigate the influence of several conditions affecting MN frequency. Random effects models were mostly used to investigate MN predictors. The estimated spontaneous MN frequency was 0.74 parts per thousand (95% CI 0.52-1.05). Only staining among technical features influenced MN frequency, with an abnormal increase for non-DNA-specific stains. No effect of gender was evident, while the trend for age was highly significant (p < 0.001). Most occupational exposures and a diagnosis of cancer significantly increased MN and other endpoints frequencies. MN frequency increased in heavy smoking (>= 40 cig/day. FR = 1.37:95% CI 1.03-.82) and decreased with daily fruit consumption (FR = 0.68; 95% CI 0.50-0.91). The results of the HUMNXL, project identified priorities for validation studies, increased the basic knowledge of the assay, and contributed to the creation of a laboratory network which in perspective may allow the evaluation of disease risk associated with MN frequency. (C) 2011 Elsevier B.V. All rights reserved.

Cinética da enzima alfa-galactosidase a e investigação de doença de fabry em pacientes hemodialisados

A Alfa-galactosidase A (α-Gal A) humana é uma enzima lisossômica que quando deficiente causa a doença de Fabry. A doença de Fabry é uma esfingolipidose cuja principal causa de morbi-mortalidade é a insuficiência renal crônica (IRC). O objetivo deste estudo foi a implantação de um protocolo laboratorial que permita o diagnóstico da doença de Fabry em plasma e leucócitos, além da análise das características cinéticas da enzima α-Gal A em plasma e busca ativa da doença em 25 indivíduos com IRC de causa desconhecida. Também foram avaliadas a reprodutibilidade e a estabilidade do método enzimático. A padronização dos ensaios foi realizada com o substrato fluorescente 4-metilumbeliferil-α-Dgalactopiranosídeo. A reprodutibilidade foi avaliada utilizando amostras de plasma aliquotadas a 4ºC, -20ºC e -70ºC, analisadas uma vez ao mês por 6 meses e a estabilidade da fluorescência por até 24 horas após o término do ensaio enzimático. A padronização permitiu a implantação de valores de referência da α-Gal A para o estado do Pará, de 4 a 28 nmoles/h/mL (plasma) e de 20 a 96 nmoles/h/mg proteína (leucócitos). A enzima α-Gal A se mostrou termolábil, visto que com apenas 1 minuto de pré-incubação das amostras a 60ºC, sua atividade decaiu 71,09%. Com relação ao tempo de incubação, a atividade enzimática apresentou uma disposição linear crescente entre 15 a 180 minutos de incubação. A α-Gal A apresentou maior atividade no pH 4,8, o Km encontrado para a α-Gal A foi de 1,007 mM e a Vmáx foi 30,9 nmoles/h/mL. A melhor temperatura de armazenamento de plasma até o ensaio enzimático é -20ºC, onde foi observada menor variação em um período máximo de 6 meses. O método enzimático utilizado é estável, mesmo após 24 horas do término do ensaio, em temperatura ambiente. Com relação aos pacientes com IRC de causa desconhecida, todos apresentaram valor de atividade da α-Gal A dentro dos parâmetros de referência e, portanto, nenhum foi diagnosticado com doença de Fabry. O entendimento da cinética da α-Gal A e do seu comportamento in vitro possibilita um melhor diagnóstico laboratorial da doença de Fabry gerando dados para futuras comparações com indivíduos afetados por mutações nesta enzima

Comparative evaluation of serologic tests for celiac disease: a European initiative toward standardization.

BACKGROUND: Serologic methods have been used widely to test for celiac disease and have gained importance in diagnostic definition and in new epidemiologic findings. However, there is no standardization, and there are no reference protocols and materials. METHODS: The European working group on Serological Screening for Celiac Disease has defined robust noncommercial test protocols for immunoglobulin (Ig)G and IgA gliadin antibodies and for IgA autoantibodies against endomysium and tissue transglutaminase. Standard curves were linear in the decisive range, and intra-assay variation coefficients were less than 5% to 10%. Calibration was performed with a group reference serum. Joint cutoff limits were used. Seven laboratories took part in the final collaborative study on 252 randomized sera classified by histology (103 pediatric and adult patients with active celiac disease, 89 disease control subjects, and 60 blood donors). RESULTS: IgA autoantibodies against endomysium and tissue transglutaminase rendered superior sensitivity (90% and 93%, respectively) and specificity (99% and 95%, respectively) over IgA and IgG gliadin antibodies. Tissue transglutaminase antibody testing showed superior receiver operating characteristic performance compared with gliadin antibodies. The K values for interlaboratory reproducibility showed superiority for IgA endomysium (0.93) in comparison with tissue transglutaminase antibodies (0.83) and gliadin antibodies (0.82 for IgG, 0.62 for IgA). CONCLUSIONS: Basic criteria of standardization and quality assessment must be fulfilled by any given test protocol proposed for serologic investigation of celiac disease. The working group has produced robust test protocols and reference materials available for standardization to further improve reliability of serologic testing for celiac disease.

Development and standardization of a protocol for sperm cryopreservation of two important commercial oyster species

Dissertação de mestrado, Aquacultura e Pescas, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

Standardization of cytokine flow cytometry assays

Affiliation: Faculté de médecine, Université de Montréal & CANVAC

Validated HPLC method for the standardization of Phyllanthus niruri (herb and commercial extracts) using corilagin as a phytochemical marker

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Detection of Cryptosporidium parvum oocysts in calf fecal samples by direct immunofluorescence assay

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Teste imunoenzimático (enzyme-linked immunosorbent assay) para diagnóstico da cisitcercose bovina e estudo da cinética de produção de anticorpos contra-Cysticercus bovis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Colorimetric assay of ethanol using alcohol dehydrogenase from dry baker's yeast

Alcohol dehydrogenases (ADHs) are oxidoreductases present in animal tissues, plants, and microorganisms. These enzymes attract major scientific interest for the evolutionary perspectives, afforded by their wide occurrence in nature, and for their use in synthesis, thanks to their broad substrate specificity and stereoselectivity. In the present study, the standardization of the activity of the alcohol dehydrogenase from baker's yeast was accomplished, and the pH and temperature stability showed, that the enzyme presented a high stability to pH 6.0-7.0 and the thermal stability were completely maintained up to 50 degrees C during 1 h. The assays of ethanol (detection range 1-5 mM or 4.6 x 10(-2) to 23.0 x 10(-2) g/L) in different samples in alcoholic beverages, presented a maximum deviation of only 7.2%. The standard curve and the analytic curve of this method meet the conditions of precision, sensitivity, simplicity, and low cost, required for a useable analytical method. (c) 2006 Elsevier B.V. All rights reserved.

Monitoring dendritic cells in clinical practice using a new whole blood single-platform TruCOUNT assay

Dendritic cells (DC) from distinct DC subsets are essential contributors to normal human immune responses. Despite this, reliable assays that enable DC to be counted precisely have been slow to evolve. We have now developed a new single-platform flow cytometric assay based on TruCOUN(TM) beads and the whole blood Lyse/No-Wash protocol that allows precise counting of the CD14(-) blood DC subsets: CD11c(+)CD16(-) DC, CD11c(+)CD16(+) DC, CD123(hi) DC, CD1c(+) DC and BDCA-3(+) DC. This assay requires 50 mul of whole blood; does not rely on a hematology blood analyser for the absolute DC counts; allows DC counting in EDTA samples 24 It after collection; and is suitable for cord blood and peripheral blood. The data is highly reproducible with intra-assay and inter-assay coefficients of variation less than 3% and 11%, respectively. This assay does not produce the DC-T lymphocyte conjugates that result in DC counting abnormalities in conventional gradient-density separation procedures. Using the TruCOUNT assay, we established that absolute blood DC counts reduce with age in healthy individuals. In preliminary studies, we found a significantly lower absolute blood CD11c(+)CD16(+) DC count in stage III/IV versus stage I/II breast carcinoma patients and a lower absolute blood CD123(hi) DC count in multiple myeloma patients, compared to age-matched controls. These data indicate that scientific progress in DC counting technology will lead to the global standardization of DC counting and allow clinically meaningful data to be obtained. (C) 2003 Elsevier B.V. All rights reserved.

Development of a colorimetric assay for heparanase activity suitable for kinetic analysis and inhibitor screening

The role that heparanase plays during metastasis and angiogenesis in tumors makes it an attractive target for cancer therapeutics. Despite this enzyme’s significance, most of the assays developed to measure its activity are complex. Moreover, they usually rely on labeling variable preparations of the natural substrate heparan sulfate, making comparisons across studies precarious. To overcome these problems, we have developed a convenient assay based on the cleavage of the synthetic heparin oligosaccharide fondaparinux. The assay measures the appearance of the disaccharide product of heparanase-catalyzed fondaparinux cleavage colorimetrically using the tetrazolium salt WST-1. Because this assay has a homogeneous substrate with a single point of cleavage, the kinetics of the enzyme can be reliably characterized, giving a Km of 46 μM and a kcat of 3.5 s−1 with fondaparinux as substrate. The inhibition of heparanase by the published inhibitor, PI-88, was also studied, and a Ki of 7.9 nM was determined. The simplicity and robustness of this method, should, not only greatly assist routine assay of heparanase activity but also could be adapted for high-throughput screening of compound libraries, with the data generated being directly comparable across studies.

Towards a framework for business process standardization

Organizations increasingly seek to achieve operational excellence by standardizing business processes. Standardization initiatives may have different purposes, such as process streamlining, process automation, or even process outsourcing. However, standardization of processes is easier said than done. Standardization success depends on various factors, such as existent IT capabilities, available standard frameworks, market situation, and the processes’ nature, such as their level of routine or structuredness. This paper uncovers the complex nature and relative influence of process-internal and -environmental factors relevant to process standardization, by discussing three case studies from different industries. The findings are summarized in a set of initial conjectures about successful process standardization. This exploratory research is a first step towards uncovering the characteristics of successful process standardization efforts.

A surface plasmon resonance-based solution affinity assay for heparan sulfate-binding proteins

A surface plasmon resonance-based solution affinity assay is described for measuring the Kd of binding of heparin/heparan sulfate-binding proteins with a variety of ligands. The assay involves the passage of a pre-equilibrated solution of protein and ligand over a sensor chip onto which heparin has been immobilised. Heparin sensor chips prepared by four different methods, including biotin–streptavidin affinity capture and direct covalent attachment to the chip surface, were successfully used in the assay and gave similar Kd values. The assay is applicable to a wide variety of heparin/HS-binding proteins of diverse structure and function (e.g., FGF-1, FGF-2, VEGF, IL-8, MCP-2, ATIII, PF4) and to ligands of varying molecular weight and degree of sulfation (e.g., heparin, PI-88, sucrose octasulfate, naphthalene trisulfonate) and is thus well suited for the rapid screening of ligands in drug discovery applications.